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October 2006<br />

<strong>EPA</strong>/600/R-05/144bF<br />

<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong> <strong>of</strong> <strong>II</strong>


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong><br />

National Center <strong>for</strong> Environmental Assessment-RTP Division<br />

Office <strong>of</strong> Research and Development<br />

U.S. Environmental Protection Agency<br />

Research Triangle Park, NC<br />

<strong>EPA</strong>/600/R-05/144bF<br />

October 2006


PREFACE<br />

National Ambient <strong>Air</strong> <strong>Quality</strong> Standards (NAAQS) are promulgated by the United States<br />

Environmental Protection Agency (<strong>EPA</strong>) to meet requirements set <strong>for</strong>th in Sections 108 and 109<br />

<strong>of</strong> the U.S. Clean <strong>Air</strong> Act. Those two Clean <strong>Air</strong> Act sections require the <strong>EPA</strong> Administrator<br />

(1) to list widespread air pollutants that reasonably may be expected to endanger public health or<br />

welfare; (2) to issue air quality criteria <strong>for</strong> them that assess the latest available scientific<br />

in<strong>for</strong>mation on nature and effects <strong>of</strong> ambient exposure to them; (3) to set “primary” NAAQS to<br />

protect human health with adequate margin <strong>of</strong> safety and to set “secondary” NAAQS to protect<br />

against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade<br />

materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS<br />

<strong>for</strong> a given listed pollutant or class <strong>of</strong> pollutants.<br />

<strong>Lead</strong> was first listed in the mid-1970’s as a “criteria air pollutant” requiring NAAQS<br />

regulation. The scientific in<strong>for</strong>mation pertinent to Pb NAAQS development available at the time<br />

was assessed in the <strong>EPA</strong> document <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>; published in 1977. Based on<br />

the scientific assessments contained in that 1977 lead air quality criteria document (1977 <strong>Lead</strong><br />

AQCD), <strong>EPA</strong> established a 1.5 µg/m 3 (maximum quarterly calendar average) Pb NAAQS in<br />

1978.<br />

To meet Clean <strong>Air</strong> Act requirements noted above <strong>for</strong> periodic review <strong>of</strong> criteria and<br />

NAAQS, new scientific in<strong>for</strong>mation published since the 1977 <strong>Lead</strong> AQCD was later assessed in<br />

a revised <strong>Lead</strong> AQCD and Addendum published in 1986 and in a Supplement to the 1986<br />

AQCD/Addendum published by <strong>EPA</strong> in 1990. A 1990 <strong>Lead</strong> Staff Paper, prepared by <strong>EPA</strong>’s<br />

Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards (OPQPS), drew upon key findings and conclusions<br />

from the 1986 <strong>Lead</strong> AQCD/Addendum and 1990 Supplement (as well as other OAQPSsponsored<br />

lead exposure/risk analyses) in posing options <strong>for</strong> the <strong>EPA</strong> Administrator to consider<br />

with regard to possible revision <strong>of</strong> the Pb NAAQS. However, <strong>EPA</strong> chose not to revise the Pb<br />

NAAQS at that time. Rather, as part <strong>of</strong> implementing a broad 1991 U.S. <strong>EPA</strong> Strategy <strong>for</strong><br />

Reducing <strong>Lead</strong> Exposure, the Agency focused primarily on regulatory and remedial clean-up<br />

ef<strong>for</strong>ts to reduce Pb exposure from a variety <strong>of</strong> non-air sources that posed more extensive public<br />

health risks, as well as other actions to reduce air emissions.<br />

The purpose <strong>of</strong> this revised <strong>Lead</strong> AQCD is to critically assess the latest scientific<br />

in<strong>for</strong>mation that has become available since the literature assessed in the 1986 <strong>Lead</strong><br />

<strong>II</strong>-iii


AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new<br />

in<strong>for</strong>mation useful in evaluating health and environmental effects <strong>of</strong> ambient air lead exposures.<br />

This includes discussion in this document <strong>of</strong> in<strong>for</strong>mation regarding: the nature, sources,<br />

distribution, measurement, and concentrations <strong>of</strong> lead in the environment; multimedia lead<br />

exposure (via air, food, water, etc.) and biokinetic modeling <strong>of</strong> contributions <strong>of</strong> such exposures<br />

to concentrations <strong>of</strong> lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,<br />

as key indices <strong>of</strong> lead exposure).; characterization <strong>of</strong> lead health effects and associated exposureresponse<br />

relationships; and delineation <strong>of</strong> environmental (ecological) effects <strong>of</strong> lead. This final<br />

version <strong>of</strong> the revised <strong>Lead</strong> AQCD mainly assesses pertinent literature published or accepted <strong>for</strong><br />

publication through December 2005.<br />

The First External Review Draft (dated December 2005) <strong>of</strong> the revised <strong>Lead</strong> AQCD<br />

underwent public comment and was reviewed by the Clean <strong>Air</strong> Scientific Advisory Committee<br />

(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public<br />

comments and CASAC recommendations received were taken into account in making<br />

appropriate revisions and incorporating them into a Second External Review Draft (dated May,<br />

2006) which was released <strong>for</strong> further public comment and CASAC review at a public meeting<br />

held June 28-29, 2006. In addition, still further revised drafts <strong>of</strong> the Integrative Synthesis<br />

chapter and the Executive Summary were then issued and discussed during an August 15, 2006<br />

CASAC teleconference call. Public comments and CASAC advice received on these latter<br />

materials, as well as Second External Review Draft materials, were taken into account in making<br />

and incorporating further revisions into this final version <strong>of</strong> this <strong>Lead</strong> AQCD, which is being<br />

issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present<br />

document provide inputs to an associated <strong>Lead</strong> Staff Paper prepared by <strong>EPA</strong>’s Office <strong>of</strong> <strong>Air</strong><br />

<strong>Quality</strong> Planning and Standards (OAQPS), which poses options <strong>for</strong> consideration by the <strong>EPA</strong><br />

Administrator with regard to proposal and, ultimately, promulgation <strong>of</strong> decisions on potential<br />

retention or revision, as appropriate, <strong>of</strong> the current Pb NAAQS.<br />

Preparation <strong>of</strong> this document has been coordinated by staff <strong>of</strong> <strong>EPA</strong>’s National Center <strong>for</strong><br />

Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific<br />

staff, together with experts from academia, contributed to writing <strong>of</strong> document chapters. Earlier<br />

drafts <strong>of</strong> document materials were reviewed by scientists from other <strong>EPA</strong> units and by non-<strong>EPA</strong><br />

experts in several public peer consultation workshops held by <strong>EPA</strong> in July/August 2005.<br />

<strong>II</strong>-iv


NCEA acknowledges the valuable contributions provided by authors, contributors, and<br />

reviewers and the diligence <strong>of</strong> its staff and contractors in the preparation <strong>of</strong> this document. The<br />

constructive comments provided by public commenters and CASAC that served as valuable<br />

inputs contributing to improved scientific and editorial quality <strong>of</strong> the document are also<br />

acknowledged by NCEA.<br />

DISCLAIMER<br />

Mention <strong>of</strong> trade names or commercial products in this document does not constitute<br />

endorsement or recommendation <strong>for</strong> use.<br />

.<br />

<strong>II</strong>-v


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(Second External Review Draft)<br />

VOLUME I<br />

EXECUTIVE SUMMARY .........................................................................................................E-1<br />

1. INTRODUCTION ........................................................................................................... 1-1<br />

2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD.......................................... 2-1<br />

3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED<br />

ENVIRONMENTAL CONCENTRATIONS.................................................................. 3-1<br />

4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD<br />

BURDEN IN HUMANS.................................................................................................. 4-1<br />

5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS<br />

AND IN VITRO TEST SYSTEMS................................................................................. 5-1<br />

6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS<br />

ASSOCIATED WITH LEAD EXPOSURE .................................................................... 6-1<br />

7. ENVIRONMENTAL EFFECTS OF LEAD ................................................................... 7-1<br />

8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH<br />

EFFECTS INFORMATION............................................................................................ 8-1<br />

VOLUME <strong>II</strong><br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS) ............................................. AX4-1<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN<br />

LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS) ................ AX5-1<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH<br />

EFFECTS ASSOCIATED WITH LEAD EXPOSURE) ................................. AX6-1<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD).................................. AX7-1<br />

<strong>II</strong>-vi


Table <strong>of</strong> Contents<br />

Page<br />

PREFACE .................................................................................................................................. <strong>II</strong>-iii<br />

DISCLAIMER ............................................................................................................................ <strong>II</strong>-v<br />

List <strong>of</strong> Tables .............................................................................................................................. <strong>II</strong>-x<br />

Authors, Contributors, and Reviewers..................................................................................... <strong>II</strong>-xxi<br />

U.S. Environmental Protection Agency Project Team <strong>for</strong> Development <strong>of</strong> <strong>Air</strong><br />

<strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>................................................................................................. <strong>II</strong>-xxvii<br />

U.S. Environmental Protection Agency Science Advisory Board (SAB) Staff<br />

Office Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)........................................... <strong>II</strong>-xxix<br />

Abbreviations and Acronyms ................................................................................................ <strong>II</strong>-xxxi<br />

AX4. CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS,<br />

AND MODELS OF LEAD BURDEN IN HUMANS) ................................... AX4-1<br />

REFERENCES ...................................................................................................... AX4-44<br />

<strong>II</strong>-vii


List <strong>of</strong> Tables<br />

AX4-1 Analytical Methods <strong>for</strong> Determining <strong>Lead</strong> in Blood, Urine, and Hair ............ AX4-2<br />

AX4-2 Summary <strong>of</strong> Selected Measurements <strong>of</strong> PbB Levels in Humans .................... AX4-4<br />

AX4-3 Bone <strong>Lead</strong> Measurements in Cadavers............................................................ AX4-7<br />

AX4-4 Bone <strong>Lead</strong> Measurements in Environmentally-Exposed Subjects .................. AX4-9<br />

AX4-5 Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects................... AX4-12<br />

AX4-6 Bone <strong>Lead</strong> Contribution to PbB..................................................................... AX4-19<br />

AX4-7 Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects................................. AX4-22<br />

AX4-8 Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects..... AX4-30<br />

AX4-9 <strong>Lead</strong> in Deciduous Teeth from Urban and Remote Environments................ AX4-36<br />

AX4-10 <strong>Lead</strong> in Deciduous Teeth from Polluted Environments................................. AX4-38<br />

AX4-11 Summary <strong>of</strong> Selected Measurements <strong>of</strong> Urine <strong>Lead</strong> Levels in Humans ....... AX4-39<br />

AX4-12 Summary <strong>of</strong> Selected Measurements <strong>of</strong> Hair <strong>Lead</strong> Levels in Humans ......... AX4-42<br />

<strong>II</strong>-x<br />

Page


Authors, Contributors, and Reviewers<br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS)<br />

Chapter Managers/Editors<br />

Dr. James Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principal Authors<br />

Dr. Brian Gulson—Graduate School <strong>of</strong> the Environment, Macquarie University<br />

Sydney, NSW 2109, Australia<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS<br />

AND LABORATORY ANIMALS)<br />

Chapter Managers/Editors<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principal Authors<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Sections 5-2, 5-10)<br />

<strong>II</strong>-xxi


Principal Authors<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Stephen Lasley—Dept. <strong>of</strong> Biomedical and Therapeutic Sciences, Univ. <strong>of</strong> Illinois College <strong>of</strong><br />

Medicine, PO Box 1649, Peoria, IL 61656 (Section 5.3)<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Section 5.3)<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001<br />

(Section 5.4)<br />

Dr. N.D. Vaziri—Division <strong>of</strong> Nephrology and Hypertension, University <strong>of</strong> Cali<strong>for</strong>nia – Irvine<br />

Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868 (Section 5.5)<br />

Dr. John Pierce Wise, Sr.—Maine Center <strong>for</strong> Toxicology and Environmental Health,<br />

Department <strong>of</strong> Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME<br />

04104-9300 (Section 5.6)<br />

Dr. Harvey C. Gonick—David Geffen School <strong>of</strong> Medicine, University <strong>of</strong> Cali<strong>for</strong>nia at<br />

Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049 (Sections 5.7, 5.11)<br />

Dr. Gene E. Watson—University <strong>of</strong> Rochester Medical Center, Box 705, Rochester, NY 14642<br />

(Section 5.8)<br />

Dr. Rodney Dietert—Institute <strong>for</strong> Comparative and Environmental Toxicology, College <strong>of</strong><br />

Veterinary Medicine, Cornell University, Ithaca, NY 14853 (Section 5.9)<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David A. Lawrence—Dept <strong>of</strong> Environmental and Clinical Immunology, Empire State Plaza<br />

P.O. Box 509, Albany, NY 12201<br />

<strong>II</strong>-xxii


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Michael J. McCabe, Jr.—Dept <strong>of</strong> Environmental Medicine, University <strong>of</strong> Rochester,<br />

575 Elmwood Avenue, Rochester, NY 14642<br />

Dr. Theodore I. Lidsky—New York State Institute <strong>for</strong> Basic Research, 1050 Forest RD,<br />

Staten Island, NY 10314<br />

Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001<br />

Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD<br />

EXPOSURE EFFECTS)<br />

Chapter Managers/Editors<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xxiii


Principal Authors<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. David Bellinger—Children’s Hospital, Farley Basement, Box 127, 300 Longwood Avenue,<br />

Boston, MA 02115 (Section 6.10)<br />

Dr. Margit Bleecker—Center <strong>for</strong> Occupational and Environmental Neurology, 2 Hamill Road,<br />

Suite 225, Baltimore, MD 21210 (Section 6.3)<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.<br />

Akron, NY 14001 (Section 6.8, 6.9)<br />

Dr. Kim Dietrich—University <strong>of</strong> Cincinnati College <strong>of</strong> Medicine, 3223 Eden Avenue,<br />

Kettering Laboratory, Room G31, Cincinnati, OH 45267 (Section 6.2)<br />

Dr. Pam Factor-Litvak—Columbia University Mailman School <strong>of</strong> Public Health, 722 West<br />

168th Street, Room 1614, New York, NY 10032 (Section 6.6)<br />

Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713 (Section 6.10)<br />

Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Mérida, Yucatán, México & National Institute<br />

<strong>of</strong> Public Health, Cuernavaca, Morelos, Mexico (Section 6.5)<br />

Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School <strong>of</strong> Public Health<br />

& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112<br />

(Section 6.7)<br />

Dr. Kyle Steenland—Rollins School <strong>of</strong> Public Health, Emory University, 1518 Clifton Road,<br />

Room 268, Atlanta, GA 30322 (Section 6.7)<br />

Dr. Virginia Weaver—Johns Hopkins Bloomberg School <strong>of</strong> Public Health, 615 North Wolfe<br />

Street, Room 7041, Baltimore, MD 21205 (Section 6.4)<br />

Contributors and Reviewers<br />

Dr. J. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Kazuhiko Ito—Nelson Institute <strong>of</strong> Environmental Medicine, New York University School <strong>of</strong><br />

Medicine, Tuxedo, NY 10987<br />

<strong>II</strong>-xxiv


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Kathryn Mahaffey—Office <strong>of</strong> Prevention, Pesticides and Toxic Substances,<br />

U.S. Environmental Protection Agency, Washington, DC 20460<br />

Dr. Karen Martin—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Chapter Manager/Editor<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principle Authors<br />

Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,<br />

Ontario, L5N 3C9 Canada (Section 7.1)<br />

Dr. James Kaste—Department <strong>of</strong> Earth Sciences, Dartmouth College, 352 Main Street, Hanover,<br />

NH 03755 (Section 7.1)<br />

Dr. John Drexler—Department <strong>of</strong> Geological Sciences, University <strong>of</strong> Colorado, 1216 Gillespie<br />

Drive, Boulder, CO 80305 (Section 7.1)<br />

Dr. Chris Johnson—Department <strong>of</strong> Civil and Environmental Engineering, Syracuse University,<br />

365 Link Hall, Syracuse, NY 13244 (Section 7.1)<br />

Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321<br />

(Section 7.2)<br />

<strong>II</strong>-xxv


Principle Authors<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Dwayne Moore—Cantox Environmental, Inc., 1550A Laperriere Avenue, Suite 103,<br />

Ottawa, Ontario, K1Z 7T2 Canada (Section 7.2)<br />

Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004<br />

(Section 7.2)<br />

Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,<br />

Winchester, MA 01890 (Section 7.3)<br />

Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite<br />

202, Winchester, MA 01890 (Section 7.3)<br />

Contributors and Reviewers<br />

Dr. Jerome Nriagu—Department <strong>of</strong> Environmental Health Sciences, 109 South Observatory,<br />

University <strong>of</strong> Michigan, Ann Arbor, MI 48109<br />

Dr. Judith Weis—Department <strong>of</strong> Biology, Rutgers University, Newark, NJ 07102<br />

Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Ginger Tennant—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Gail Lacey—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental Protection<br />

Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xxvi


Executive Direction<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

Dr. Lester D. Grant (Director)—National Center <strong>for</strong> Environmental Assessment-RTP Division,<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Scientific Staff<br />

Dr. Lori White (<strong>Lead</strong> Team <strong>Lead</strong>er)—National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. James S. Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Robert Elias—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Dr. Brooke Hemming—National Center <strong>for</strong> Environmental Assessment (B243-01), U.S.<br />

Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Anuradha Muldipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Mary Ross— National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xxvii


Technical Support Staff<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(cont’d)<br />

Mr. Douglas B. Fennell—Technical In<strong>for</strong>mation Specialist, National Center <strong>for</strong> Environmental<br />

Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC<br />

27711 (Retired)<br />

Ms. Emily R. Lee—Management Analyst, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Diane H. Ray—Program Specialist, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Donna Wicker—Administrative Officer, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Mr. Richard Wilson—Clerk, National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Document Production Staff<br />

Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Mr. John A. Bennett—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,<br />

Suite 1450, McLean, VA 22102<br />

Ms. Sandra L. Hughey—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards<br />

Mill Road, Suite 201, Raleigh, NC 27607<br />

Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

<strong>II</strong>-xxviii


Chair<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,<br />

Albuquerque, NM<br />

Members<br />

Dr. Joshua Cohen—Faculty, Center <strong>for</strong> the Evaluation <strong>of</strong> Value and Risk, Institute <strong>for</strong> Clinical<br />

Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA<br />

Dr. Deborah Cory-Slechta—Director, University <strong>of</strong> Medicine and Dentistry <strong>of</strong> New Jersey and<br />

Rutgers State University, Piscataway, NJ<br />

Dr. Ellis Cowling*—University Distinguished Pr<strong>of</strong>essor-at-Large, North Carolina State<br />

University, Colleges <strong>of</strong> Natural Resources and Agriculture and Life Sciences, North Carolina<br />

State University, Raleigh, NC<br />

Dr. James D. Crapo [M.D.]*—Pr<strong>of</strong>essor, Department <strong>of</strong> Medicine, National Jewish Medical and<br />

Research Center, Denver, CO<br />

Dr. Bruce Fowler—Assistant Director <strong>for</strong> Science, Division <strong>of</strong> Toxicology and Environmental<br />

Medicine, Office <strong>of</strong> the Director, Agency <strong>for</strong> Toxic Substances and Disease Registry, U.S.<br />

Centers <strong>for</strong> Disease Control and Prevention (ATSDR/CDC), Chamblee, GA<br />

Dr. Andrew Friedland—Pr<strong>of</strong>essor and Chair, Environmental Studies Program, Dartmouth<br />

College, Hanover, NH<br />

Dr. Robert Goyer [M.D.]—Emeritus Pr<strong>of</strong>essor <strong>of</strong> Pathology, Faculty <strong>of</strong> Medicine, University <strong>of</strong><br />

Western Ontario (Canada), Chapel Hill, NC<br />

Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO<br />

Dr. Bruce Lanphear [M.D.]—Sloan Pr<strong>of</strong>essor <strong>of</strong> Children’s Environmental Health, and the<br />

Director <strong>of</strong> the Cincinnati Children’s Environmental Health Center at Cincinnati Children’s<br />

Hospital Medical Center and the University <strong>of</strong> Cincinnati, Cincinnati, OH<br />

Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (<strong>US</strong>GS),<br />

Menlo Park, CA<br />

<strong>II</strong>-xxix


Members<br />

(cont’d)<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

(cont’d)<br />

Dr. Frederick J. Miller*—Consultant, Cary, NC<br />

Dr. Paul Mushak—Principal, PB Associates, and Visiting Pr<strong>of</strong>essor, Albert Einstein College <strong>of</strong><br />

Medicine (New York, NY), Durham, NC<br />

Dr. Michael Newman—Pr<strong>of</strong>essor <strong>of</strong> Marine Science, School <strong>of</strong> Marine Sciences, Virginia<br />

Institute <strong>of</strong> Marine Science, College <strong>of</strong> William & Mary, Gloucester Point, VA<br />

Mr. Richard L. Poirot*—Environmental Analyst, <strong>Air</strong> Pollution Control Division, Department <strong>of</strong><br />

Environmental Conservation, Vermont Agency <strong>of</strong> Natural Resources, Waterbury, VT<br />

Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA<br />

Dr. Joel Schwartz—Pr<strong>of</strong>essor, Environmental Health, Harvard University School <strong>of</strong> Public<br />

Health, Boston, MA<br />

Dr. Frank Speizer [M.D.]*—Edward Kass Pr<strong>of</strong>essor <strong>of</strong> Medicine, Channing Laboratory, Harvard<br />

Medical School, Boston, MA<br />

Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,<br />

Moscow, ID<br />

Dr. Barbara Zielinska*—Research Pr<strong>of</strong>essor, Division <strong>of</strong> Atmospheric Science, Desert Research<br />

Institute, Reno, NV<br />

SCIENCE ADVISORY BOARD STAFF<br />

Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,<br />

Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)<br />

(Physical/Courier/FedEx Address: Fred A. Butterfield, <strong>II</strong>I, <strong>EPA</strong> Science Advisory Board Staff<br />

Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,<br />

DC 20004, Telephone: 202-343-9994)<br />

*Members <strong>of</strong> the statutory Clean <strong>Air</strong> Scientific Advisory Committee (CASAC) appointed by the<br />

U.S. <strong>EPA</strong> Administrator<br />

<strong>II</strong>-xxx


Abbreviations and Acronyms<br />

αFGF α-fibroblast growth factor<br />

AA arachidonic acid<br />

AAL active avoidance learning<br />

AAS atomic absorption spectroscopy<br />

ABA β-aminoisobutyric acid<br />

ACBP Achenbach Child Behavior Pr<strong>of</strong>ile<br />

ACE angiotensin converting enzyme<br />

ACh acetylcholine<br />

AChE acetylcholinesterase<br />

ACR acute-chronic ratio<br />

AD adult<br />

ADC analog digital converter<br />

ADP adenosine diphosphate<br />

AE anion exchange<br />

AEA N-arachidonylethanolamine<br />

AFC antibody <strong>for</strong>ming cells<br />

2-AG 2-arachidonylglycerol<br />

A horizon uppermost layer <strong>of</strong> soil (litter and humus)<br />

AHR aryl hydrocarbon receptor<br />

AI angiotensin I<br />

ALA *-aminolevulinic acid<br />

ALAD *-aminolevulinic acid dehydratase<br />

ALAS aminolevulinic acid synthetase<br />

ALAU urinary δ-aminolevulinic acid<br />

ALD aldosterone<br />

ALS amyotrophic lateral sclerosis<br />

ALT alanine aminotransferase<br />

ALWT albumin weight<br />

AMEM Alpha Minimal Essential Medium<br />

AMP adenosine monophosphate<br />

ANCOVA analysis <strong>of</strong> covariance<br />

ANF atrial natriuretic factor<br />

Ang <strong>II</strong> angiotensin <strong>II</strong><br />

ANOVA analysis <strong>of</strong> variance<br />

<strong>II</strong>-xxxi


ANP atrial natriuretic peptide<br />

AP alkaline phosphatase<br />

AP-1 activated protein-1<br />

ApoE apolipoprotein E<br />

AQCD <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> Document<br />

Arg arginine<br />

AS52 cells derived from the CHO cell line<br />

ASGP-R aceyl glycoprotein receptor<br />

AST aspartate aminotransferase<br />

ASV anode stripping voltammetry<br />

3-AT 3-aminotriazole; 3-amino triazide<br />

ATP adenosine triphosphate<br />

ATP1A2 sodium-potassium adenosine triphosphase α2<br />

ATPase adenosine triphosphatase<br />

ATSDR Agency <strong>for</strong> Toxic Substances and Disease Research<br />

AVCD atrioventricular conduction deficit<br />

AVS acid volatile sulfide<br />

AWQC ambient water quality criteria<br />

$ beta-coefficient; slope <strong>of</strong> an equation<br />

$FGF $-fibroblast growth factor<br />

17$–HS 17$-hydroxysteriod<br />

3$-HSD 3$-hydroxysteriod dehydrogenase<br />

17$-HSDH 17$-hydroxysteriod dehydrogenase<br />

6$-OH-cortisol 6-$-hydroxycortisol<br />

B both<br />

BAEP brainstem auditory-evoked potentials<br />

BAER brainstem auditory-evoked responses<br />

BAF bioaccumulation factor<br />

B cell B lymphocyte<br />

BCFs bioconcentration factors<br />

BCS bovine calf serum<br />

BDNF brain derived neurotrophic factor<br />

BDWT body weight changes<br />

BEI biological exposure index<br />

BFU-E blood erythroid progenitor<br />

<strong>II</strong>-xxxii


BLL blood lead level<br />

BLM biotic ligand model<br />

BM basement membrane<br />

BMI body mass index<br />

BDNF brain-derived neurotrophic factor<br />

BOTMP Bruinicks-Oseretsky Test <strong>of</strong> Motor Pr<strong>of</strong>iciency<br />

BP blood pressure<br />

BPb blood lead concentration<br />

BSA bovine serum albumin<br />

BSI Brief Symptom Inventory<br />

BTQ Boston Teacher Questionnaire<br />

BUN blood urea nitrogen<br />

bw, b. wt., BW body weight<br />

C3H10T/12 mouse embryo cell line<br />

C3, C4 complement proteins<br />

CA chromosome aberration<br />

CA3 cornu ammonis 3 region <strong>of</strong> hippocampus<br />

45 Ca calcium-45 radionuclide<br />

Ca-ATP calcium-dependent adenosine triphosphate<br />

Ca-ATPase calcium-dependent adenosine triphosphatase<br />

CaCO3<br />

calcium carbonate<br />

CaEDTA calcium disodium ethylenediaminetetraacetic acid<br />

CAL calcitonin<br />

CaM calmodulin<br />

Ca-Mg-ATPase calcium-magnesium-dependent adenosine triphosphatase<br />

cAMP cyclic adenosinemonophosphate<br />

CaNa2 EDTA calcium disodium ethylenediaminetetraacetic acid<br />

CANTAB Cambridge Neuropsychological Testing Automated Battery<br />

CAT catalase; Cognitive Abilities Test<br />

CBCL Achenbach Child Behavior Checklist<br />

CBCL-T Total Behavior Problem Score<br />

CBL cumulative blood lead<br />

CBLI cumulative blood lead index<br />

CCB cytochalasin B<br />

CCD charge-coupled device<br />

<strong>II</strong>-xxxiii


CCE Coordination Center <strong>for</strong> Effects<br />

CCL carbon tetrachloride<br />

CCS cosmic calf serum<br />

C-CVRSA<br />

Cd cadmium<br />

coefficient <strong>of</strong> component variance <strong>of</strong> respiratory sinus<br />

arrhythmia<br />

109 Cd cadmium-109 radionuclide<br />

CdU urinary cadmium<br />

CEC cation exchange capacity<br />

CESD, CES-D Center <strong>for</strong> Epidemiologic Studies Depression (scale)<br />

GFAP glial fibrillary acidic protein<br />

CFU-E colony <strong>for</strong>ming unit blood-erythroid progenitor (cell count)<br />

CFU-GEMM colony <strong>for</strong>ming unit blood-pluripotent progenitor (cell count)<br />

CFU-GM blood granulocyte/macrophage progenitor (cell count)<br />

cGMP cyclic guanosine-3',5'-monophosphate<br />

ChAT choline acetyltransferase<br />

CHD coronary heart disease<br />

CHO Chinese hamster ovary cell line<br />

CI confidence interval<br />

CLE-SV competitive ligand-exchange/stripping voltammetry<br />

CLRTAP Convention on Long-Range Transboundary <strong>of</strong> <strong>Air</strong> Pollution<br />

CLS Cincinnati <strong>Lead</strong> Study<br />

CMC criterion maximum concentration<br />

CMI cell-mediated immunity<br />

CNS central nervous system<br />

COH cation-osmotic hemolysis<br />

ConA concanavalin A<br />

COR cortisol<br />

CoTx cotreatment<br />

COX-2 cyclooxygenase-2<br />

CP coproporphryn<br />

CPT current perception threshold<br />

cr creatinine<br />

CRAC calcium release activated calcium reflux<br />

CREB cyclic AMP-response element binding protein<br />

CRF chronic renal failure<br />

<strong>II</strong>-xxxiv


CRI chronic renal insufficiency<br />

CSF cerebrospinal fluid<br />

CuZn-SOD copper and zinc-dependent superoxide dismutase<br />

CV<br />

conduction velocity<br />

CVLT Cali<strong>for</strong>nia Verbal Learning Test<br />

CVR-R<br />

coefficient <strong>of</strong> variation <strong>of</strong> the R-R interval<br />

CYP cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)<br />

CYP3a11 cytochrome P450 3a11<br />

D D-statistic<br />

DA dopamine; dopaminergic<br />

dbcAMP dibutyryl cyclic adenosine-3',5'-monophosphate<br />

DCV distribution <strong>of</strong> conduction velocities<br />

DEAE diethylaminoethyl (chromatography)<br />

DET diffusive equilibrium thin films<br />

DEYO death <strong>of</strong> young<br />

DFS decayed or filled surfaces, permanent teeth<br />

dfs covariate-adjusted number <strong>of</strong> caries<br />

DG dentate gyrus<br />

DGT diffusive gradient thin films<br />

DL DL-statistic<br />

DMEM Dulbecco’s Minimal Essential Medium<br />

DMEM/F12 Dulbecco’s Minimal Essential Medium/Ham’s F12<br />

DMFS decayed, missing, or filled surfaces, permanent teeth<br />

DMPS 2,3-dimercaptopropane 1-sulfonate<br />

DMSA 2,3-dimercaptosuccinic acid<br />

DMT Donnan membrane technique<br />

DMTU dimethylthiourea<br />

DNA deoxyribonucleic acid<br />

DO distraction osteogenesis<br />

DOC dissolved organic carbon<br />

DOM dissolved organic carbon<br />

DOPAc 3,4-dihydroxyphenylacetic acid<br />

DPASV differential pulse anodic stripping voltammetry<br />

dp/dt rate <strong>of</strong> left ventricular isovolumetric pressure<br />

DPPD N-N-diphenyl-p-phynylene-diamine<br />

<strong>II</strong>-xxxv


DR drinking water<br />

DSA delayed spatial alternation<br />

DTC diethyl dithiocarbomate complex<br />

DTH delayed type hypersensitivity<br />

DTPA diethylenetriaminepentaacetic acid<br />

DTT dithiothreitol<br />

dw dry weight<br />

E embryonic day<br />

E2<br />

estradiol<br />

EBE early biological effect<br />

EBV Epstein-Barr virus<br />

EC European Community<br />

EC50<br />

effect concentration <strong>for</strong> 50% <strong>of</strong> test population<br />

eCB endocannabinoid<br />

ECG electrocardiogram<br />

Eco-SSL ecological soil screening level<br />

EDS energy dispersive spectrometers<br />

EDTA ethylenediaminetetraacetic acid<br />

EEDQ N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone<br />

EEG electroencephalogram<br />

EG egg<br />

EGF epidermal growth factor<br />

EGG effects on eggs<br />

EGPN egg production<br />

EKG electrocardiogram<br />

electro electrophysiological stimulation<br />

EM/CM experimental medium-to-control medium (ratio)<br />

EMEM Eagle’s Minimal Essential Medium<br />

eNOS endothelial nitric oxide synthase<br />

EP erythrocyte protoporphyrin<br />

<strong>EPA</strong> U.S. Environmental Protection Agency<br />

Epi epinephrine<br />

EPMA electron probe microanalysis<br />

EPO erythropoietin<br />

EPSC excitatory postsynaptic currents<br />

<strong>II</strong>-xxxvi


EPT macroinvertebrates from the Ephemeroptera (mayflies),<br />

Plecoptera (stoneflies), and Trichoptera (caddisflies) group<br />

ERG electroretinogram; electroretinographic<br />

ERL effects range – low<br />

ERM effects range – median<br />

EROD ethoxyresorufin-O-deethylase<br />

ESCA electron spectroscopy <strong>for</strong> chemical analysis<br />

ESRD end-stage renal disease<br />

EST estradiol<br />

ESTH eggshell thinning<br />

ET endothelein; essential tremor<br />

ETOH ethyl alcohol<br />

EXAFS extended X-ray absorption fine structure<br />

EXANES extended X-ray absorption near edge spectroscopy<br />

F F-statistic<br />

F344 Fischer 344 (rat)<br />

FAV final acute value<br />

FBS fetal bovine serum<br />

FCS fetal calf serum<br />

FCV final chronic value<br />

FD food<br />

FEF <strong>for</strong>ced expiratory flow<br />

FEP free erythrocyte protoporphyrin<br />

FERT fertility<br />

FEV1<br />

<strong>for</strong>ced expiratory volume in one second<br />

FGF fibroblast growth factor (e.g., βFGF, αFGF)<br />

FI fixed interval (operant conditioning)<br />

FIAM free ion activity model<br />

FMLP N-<strong>for</strong>myl-L-methionyl-L-leucyl-L-phenylalanine<br />

fMRI functional magnetic resonance imaging<br />

FR fixed-ratio operant conditioning<br />

FSH follicle stimulating hormone<br />

FT3 free triiodothyronine<br />

FT4 free thyroxine<br />

FTES free testosterone<br />

<strong>II</strong>-xxxvii


FT<strong>II</strong> Fagan Test <strong>of</strong> Infant Intelligence<br />

FTPLM flow-through permeation liquid membranes<br />

FURA-2 1-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benz<strong>of</strong>uranyloxy]-2-<br />

(2-amino-5-methylphenoxy) ethane-N,N,N',N'-tetraacetic acid<br />

FVC <strong>for</strong>ced vital capacity<br />

(-GT (-glutamyl transferase<br />

G gestational day<br />

GABA gamma aminobutyric acid<br />

GAG glycosaminoglycan<br />

G12 CHV79 cells derived from the V79 cell line<br />

GCI General Cognitive Index<br />

GD gestational day<br />

GDP guanosine diphosphate<br />

GEE generalized estimating equations<br />

GFAAS graphite furnace atomic absorption spectroscopy<br />

GFR glomerular filtration rate<br />

GGT (-glutamyl transferase<br />

GH growth hormone<br />

GI gastrointestinal<br />

GIME-VIP gel integrated microelectrodes combined with voltammetric<br />

in situ pr<strong>of</strong>iling<br />

GIS geographic in<strong>for</strong>mation system<br />

GLU glutamate<br />

GMAV genus mean acute value<br />

GMCV genus mean chronic value<br />

GMP guanosine monophosphate<br />

GMPH general morphology<br />

GnRH gonadotropin releasing hormone<br />

GOT aspartate aminotransferase<br />

GP gross productivity<br />

G6PD, G6PDH glucose-6-phosphate dehydrogenase<br />

GPEI glutathione S-transferase P enhancer element<br />

gp91 phox NAD(P)H oxidase<br />

GPT glutamic-pyruvic transaminase<br />

GPx glutathione peroxidase<br />

GRO growth<br />

<strong>II</strong>-xxxviii


GRP78 glucose-regulated protein 78<br />

GSD geometric standard deviation<br />

GSH reduced glutathione<br />

GSIM gill surface interaction model<br />

GSSG glutathione disulfide<br />

GST glutathione-S-transferase<br />

GSTP placental glutathione transferase<br />

GTP guanosine triphosphate<br />

GV gavage<br />

H + acidity<br />

3<br />

H hydrogen-3 radionuclide (tritium)<br />

HA humic acid; hydroxyapatite<br />

Hb hemoglobin<br />

HBEF Hubbard Brook Experimenatl Forest<br />

HBSS Hank’s Balanced Salt Solution<br />

HCG; hCG human chorionic gonadotropin<br />

Hct hematocrit<br />

HDL high-density lipoprotein (cholesterol)<br />

HEP habitat evaluation procedure<br />

HET Binghamton heterogeneous stock<br />

HFPLM hollow fiber permeation liquid membranes<br />

Hgb hemoglobin<br />

HGF hepatocyte growth factor<br />

HH hydroxylamine hydrochloride<br />

H-H high-high<br />

HHANES Hispanic Health and Nutrition Examination Survey<br />

H-L high-low<br />

HLA human leukocyte antigen<br />

H-MEM minimum essential medium/nutrient mixture–F12-Ham<br />

HMP hexose monophosphate shunt pathway<br />

HNO3<br />

nitric acid<br />

H2O2<br />

hydrogen peroxide<br />

HOME Home Observation <strong>for</strong> Measurement <strong>of</strong> Environment<br />

HOS TE human osteosarcoma cells<br />

HPLC high-pressure liquid chromatography<br />

<strong>II</strong>-xxxix


H3PO4<br />

phosphoric acid<br />

HPRT hypoxanthine phosphoribosyltransferase (gene)<br />

HR heart rate<br />

HSI habitat suitability indices<br />

H2SO4<br />

sulfuric acid<br />

HSPG heparan sulfate proteoglycan<br />

Ht hematocrit<br />

HTC hepatoma cells<br />

hTERT catalytic subunit <strong>of</strong> human telomerase<br />

HTN hypertension<br />

IBL integrated blood lead index<br />

IBL H WRAT-R integrated blood lead index H Wide Range Achievement<br />

Test-Revised (interaction)<br />

ICD International Classification <strong>of</strong> Diseases<br />

ICP inductively coupled plasma<br />

ICP-AES inductively coupled plasma atomic emission spectroscopy<br />

ICP-MS, ICPMS inductively coupled plasma mass spectrometry<br />

ID-MS isotope dilution mass spectrometry<br />

IFN interferon (e.g., IFN-()<br />

Ig immunoglobulin (e.g., IgA, IgE, IgG, IgM)<br />

IGF-1 insulin-like growth factor 1<br />

IL interleukin (e.g., IL-1, IL-1$, IL-4, IL-6, IL-12)<br />

ILL incipient lethal level<br />

immuno immunohistochemical staining<br />

IMP inosine monophosphate<br />

iNOS inducible nitric oxide synthase<br />

i.p., IP intraperitoneal<br />

IPSC inhibitory postsynaptic currents<br />

IQ intelligence quotient<br />

IRT interresponse time<br />

ISEL in situ end labeling<br />

ISI interstimulus interval<br />

i.v., IV intravenous<br />

IVCD intraventricular conduction deficit<br />

JV juvenile<br />

<strong>II</strong>-xl


KABC Kaufman Assessment Battery <strong>for</strong> Children<br />

KTEA Kaufman Test <strong>of</strong> Educational Achievement<br />

KXRF, K-XRF K-shell X-ray fluorescence<br />

LA lipoic acid<br />

LB laying bird<br />

LC lactation<br />

LC50<br />

lethal concentration at which 50% <strong>of</strong> exposed animals die<br />

LC74<br />

lethal concentration at which 74% <strong>of</strong> exposed animals die<br />

LD50<br />

lethal dose at which 50% <strong>of</strong> exposed animals die<br />

LDH lactate dehydrogenase<br />

LDL low-density lipoprotein (cholesterol)<br />

L-dopa 3,4-dihydroxyphenylalanine (precursor <strong>of</strong> dopamine)<br />

LE Long Evans (rat)<br />

LET linear energy transfer (radiation)<br />

LH luteinizing hormone<br />

LHRH luteinizing hormone releasing hormone<br />

LN lead nitrate<br />

L-NAME L-N G -nitroarginine methyl ester<br />

LOAEL lowest-observed adverse effect level<br />

LOEC lowest-observed-effect concentration<br />

LOWESS locally weighted scatter plot smoother<br />

LPO lipoperoxide<br />

LPP lipid peroxidation potential<br />

LPS lipopolysaccharide<br />

LT leukotriene<br />

LT50<br />

time to kill 50%<br />

LTER Long-Term Ecological Research (sites)<br />

LTP long term potentiation<br />

LVH left ventricular hypertrophy<br />

µPIXE micr<strong>of</strong>ocused particle induced X-ray emission<br />

µSXRF micr<strong>of</strong>ocused synchrotron-based X-ray fluorescence<br />

MA mature<br />

MA-10 mouse Leydig tumor cell line<br />

MANCOVA multivariate analysis <strong>of</strong> covariance<br />

MAO monoamine oxidase<br />

<strong>II</strong>-xli


MATC maximum acceptable threshold concentration<br />

MDA malondialdehyde<br />

MDA-TBA malondialdehyde-thiobarbituric acid<br />

MDCK kidney epithelial cell line<br />

MDI Mental Development Index (score)<br />

MDRD Modification <strong>of</strong> Diet in Renal Disease (study)<br />

MEM Minimal Essential Medium<br />

MG microglobulin<br />

Mg-ATPase magnesium-dependent adenosine triphosphatase<br />

MiADMSA monoisamyl dimercaptosuccinic acid<br />

Mi-DMSA mi monoisoamyl dimercaptosuccinic acid<br />

MK-801 NMDA receptor antagonist<br />

MLR mixed lymphocyte response<br />

MMSE Mini-Mental State Examination<br />

MMTV murine mammary tumor virus<br />

MN micronuclei <strong>for</strong>mation<br />

MND motor neuron disease<br />

MNNG N-methyl-N'-nitro-N-nitrosoguanidine<br />

MPH morphology<br />

MRI magnetic resonance imaging<br />

mRNA messenger ribonucleic acid<br />

MROD methoxyresorufin-O-demethylase<br />

MRS magnetic resonance spectroscopy<br />

MS mass spectrometry<br />

MSCA McCarthy Scales <strong>of</strong> Children’s Abiltities<br />

mSQGQs mean sediment quality guideline quotients<br />

MT metallothionein<br />

MVV maximum voluntary ventilation<br />

MW molecular weight (e.g., high-MW, low-MW)<br />

N, n number <strong>of</strong> observations<br />

N/A not available<br />

NAAQS National Ambient <strong>Air</strong> <strong>Quality</strong> Standards<br />

NAC N-acetyl cysteine<br />

NAD nicotinamide adenine dinucleotide<br />

NADH reduced nicotinamide adenine dinucleotide<br />

<strong>II</strong>-xlii


NADP nicotinamide adenine dinucleotide phosphate<br />

NAD(P)H, NADPH reduced nicotinamide adenine dinucleotide phosphate<br />

NADS nicotinamide adenine dinucleotide synthase<br />

NAF nafenopin<br />

NAG N-acetyl-$-D-glucosaminidase<br />

Na-K-ATPase sodium-potassium-dependent adenosine triphosphatase<br />

NAWQA National Water-<strong>Quality</strong> Assessment<br />

NBT nitro blue tetrazolium<br />

NCBP National Contaminant Biomonitoring Program<br />

NCD nuclear chromatin decondensation (rate)<br />

NCS newborn calf serum<br />

NCTB Neurobehavioral Core Test Battery<br />

NCV nerve conduction velocity<br />

ND non-detectable; not detected<br />

NDI nuclear divison index<br />

NE norepinephrine<br />

NES Neurobehavioral Evaluation System<br />

NF-κB nuclear transcription factor-κB<br />

NGF nerve growth factor<br />

NHANES National Health and Nutrition Examination Survey<br />

NIOSH National Institute <strong>for</strong> Occupational Safety and Health<br />

NIST National Institute <strong>for</strong> Standards and Technology<br />

NK natural killer<br />

NMDA N-methyl-D-aspartate<br />

NMDAR N-methyl-D-aspartate receptor<br />

NMR nuclear magnetic resonance<br />

NO nitric oxide<br />

NO2<br />

nitrogen dioxide<br />

NO3<br />

nitrate<br />

NOAEC no-observed-adverse-effect concentration<br />

NOAEL no-observed-adverse-effect level<br />

NOEC no-observed-effect concentration<br />

NOEL no-observed-effect level<br />

NOM natural organic matter<br />

NORs nucleolar organizing regions<br />

<strong>II</strong>-xliii


NOS nitric oxide synthase; not otherwise specified<br />

NOx<br />

nitrogen oxides<br />

NP net productivity<br />

NPSH nonprotein sulfhydryl<br />

NR not reported<br />

NRC National Research Council<br />

NRK normal rat kidney<br />

NS nonsignificant<br />

NSAID non-steroidal anti-inflammatory agent<br />

NT neurotrophin<br />

NTA nitrilotriacetic acid<br />

O2<br />

oxygen<br />

ODVP <strong>of</strong>fspring development<br />

OH hydroxyl<br />

7-OH-coumarin 7-hydroxy-coumarin<br />

1,25-(OH)2-D, 1,25-(OH)2 D3 1,25-dihydroxyvitamin D<br />

24,25-(OH)2-D3<br />

24,25-dihydroxyvitamin D<br />

25-OH-D3<br />

25-hydroxyvitamin D<br />

8-OHdG 8-hydroxy-2'-deoxyguanosine<br />

O horizon <strong>for</strong>est floor<br />

OR odds ratio; other oral<br />

OSWER Office <strong>of</strong> Solid Waste and Emergency Response<br />

P, p probability value<br />

P300 event-related potential<br />

P450 1A1 cytochrome P450 1A1<br />

P450 1A2 cytochrome P450 1A2<br />

P450 CYP3a11 cytochrome P450 3a11<br />

PAD peripheral arterial disease<br />

PAH polycyclic aromatic hydrocarbon<br />

PAI-1 plasminogen activator inhibitor-1<br />

PAR population attributable risk<br />

Pb lead<br />

203<br />

Pb lead-203 radionuclide<br />

204 206 207 208<br />

Pb, Pb, Pb, Pb stable isotopes <strong>of</strong> lead-204, -206, -207, -208, respectively<br />

210 Pb lead-210 radionuclide<br />

<strong>II</strong>-xliv


Pb(Ac)2<br />

lead acetate<br />

PbB blood lead concentration<br />

PbCl2<br />

lead chloride<br />

Pb(ClO4)2<br />

lead chlorate<br />

PBG-S porphobilinogen synthase<br />

PBMC peripheral blood mononuclear cells<br />

Pb(NO3)2<br />

lead nitrate<br />

PbO lead oxides (or litharge)<br />

PBP progressive bulbar paresis<br />

PbS galena<br />

PbU urinary lead<br />

PC12 pheochromocytoma cell<br />

PCR polymerase chain reaction<br />

PCV packed cell volume<br />

PDE phosphodiesterase<br />

PDGF platelet-derived growth factor<br />

PDI Psychomotor Development Index<br />

PEC probable effect concentration<br />

PEF expiratory peak flow<br />

PG prostaglandin (e.g., PGE2, PGF2); prostate gland<br />

PHA phytohemagglutinin A<br />

Pi inorganic phosphate<br />

PIXE particle induced X-ray emission<br />

PKC protein kinase C<br />

pl NEpi plasma norepinephrine<br />

PMA progressive muscular atrophy<br />

PMN polymorphonuclear leucocyte<br />

PMR proportionate mortality ratio<br />

PN postnatal (day)<br />

P5N pyrimidine 5'-nucleotidase<br />

PND postnatal day<br />

p.o., PO per os (oral administration)<br />

POMS Pr<strong>of</strong>ile <strong>of</strong> Mood States<br />

ppb parts per billion<br />

ppm parts per million<br />

<strong>II</strong>-xlv


PPVT-R Peabody Picture Vocabulary Test-Revised<br />

PRA plasma renin activity<br />

PRL prolactin<br />

PROG progeny counts or numbers<br />

PRR prevalence rate ratio<br />

PRWT progeny weight<br />

PST percent transferrin saturation<br />

PTH parathyroid hormone<br />

PTHrP parathyroid hormone-related protein<br />

PVC polyvinyl chloride<br />

PWM pokeweed mitogen<br />

PRWT progeny weight<br />

QA/QC quality assurance/quality control<br />

Q/V flux <strong>of</strong> air (Q) divided by volume <strong>of</strong> culture (V)<br />

r Pearson correlation coefficient<br />

R 2 multiple correlation coefficient<br />

2<br />

r correlation coefficient<br />

226<br />

Ra most stable isotope <strong>of</strong> radium<br />

R/ALAD ratio <strong>of</strong> ALAD activity be<strong>for</strong>e and after reactivation<br />

RAVLT Rey Auditory Verbal Learning Test<br />

86<br />

Rb rubidium-86 radionuclide<br />

RBA relative bioavailablity<br />

RBC red blood cell; erythrocyte<br />

RBF renal blood flow<br />

RBP retinol binding protein<br />

RBPH reproductive behavior<br />

RCPM Ravens Colored Progressive Matrices<br />

REL rat epithelial (cells)<br />

REP reproduction<br />

RHIS reproductive organ histology<br />

222<br />

Rn most stable isotope <strong>of</strong> radon<br />

RNA ribonucleic acid<br />

ROS reactive oxygen species<br />

ROS 17.2.8 rat osteosarcoma cell line<br />

RPMI 1640 Roswell Park Memorial Institute basic cell culture medium<br />

<strong>II</strong>-xlvi


RR<br />

RT<br />

RSEM<br />

RSUC<br />

RT<br />

∑SEM<br />

SA7<br />

SAB<br />

SAM<br />

SBIS-4<br />

s.c., SC<br />

SCAN<br />

SCE<br />

SCP<br />

SD<br />

SDH<br />

SDS<br />

SE<br />

SEM<br />

SES<br />

sGC<br />

SH<br />

SHBG<br />

SHE<br />

SIMS<br />

SIR<br />

SLP<br />

SM<br />

SMAV<br />

SMR<br />

SNAP<br />

SNP<br />

SO2<br />

SOD<br />

relative risk; rate ratio<br />

reaction time<br />

resorbed embryos<br />

reproductive success (general)<br />

reproductive tissue<br />

sum <strong>of</strong> the molar concentrations <strong>of</strong> simultaneously extracted<br />

metal<br />

simian adenovirus<br />

Science Advisory Board<br />

S-adenosyl-L-methionine<br />

Stan<strong>for</strong>d-Binet Intelligence Scale-4th edition<br />

subcutaneous<br />

Test <strong>for</strong> Auditory Processing Disorders<br />

selective chemical extraction; sister chromatid exchange<br />

stripping chronopotentiometry<br />

Spraque-Dawley (rat); standard deviation<br />

succinic acid dehydrogenase<br />

sodium dodecyl sulfate; Symbol Digit Substitution<br />

standard error; standard estimation<br />

standard error <strong>of</strong> the mean<br />

socioeconomic status<br />

soluble guanylate cyclase<br />

sulfhydryl<br />

sex hormone binding globulin<br />

Syrian hamster embryo cell line<br />

secondary ion mass spectrometry<br />

standardized incidence ratio<br />

synthetic leaching procedure<br />

sexually mature<br />

species mean acute value<br />

standardized mortality ratio<br />

Schneider Neonatal Assessment <strong>for</strong> Primates<br />

sodium nitroprusside<br />

sulfur dioxide<br />

superoxide dismutase<br />

<strong>II</strong>-xlvii


SOPR sperm-oocyte penetration rate<br />

SPCL sperm cell counts<br />

SPCV sperm cell viability<br />

SQGs sediment quality guidelines<br />

SRA Self Reported Antisocial Behavior scale<br />

SRD Self Report <strong>of</strong> Delinquent Behavior<br />

SRIF somatostatin<br />

SRM Standard Reference Material<br />

SRT simple reaction time<br />

SSADMF Social Security Administration Death Master File<br />

SSB single-strand breaks<br />

SSEP somatosensory-evoked potential<br />

StAR steroidogenic acute regulatory protein<br />

STORET STOrage and RETrieval<br />

SVC sensory conduction velocity<br />

SVRT simple visual reaction time<br />

T testosterone<br />

TA tail<br />

TABL time-averaged blood lead<br />

T&E threatened and endangered (species)<br />

TAT tyrosine aminotransferase<br />

TB tibia<br />

TBARS thiobarbituric acid-reactive species<br />

TBPS Total Behavior Problem Score<br />

TCDD methionine-choline-deficient diet<br />

T cell T lymphocyte<br />

TCLP toxic characteristic leaching procedure<br />

TE testes<br />

TEC threshold effect concentration<br />

TEDG testes degeneration<br />

TEL tetraethyl lead<br />

TES testosterone<br />

TEWT testes weight<br />

TF transferrin, translocation factor<br />

TG 6-thioguanine<br />

<strong>II</strong>-xlviii


TGF trans<strong>for</strong>ming growth factor<br />

TH tyrosine hydroxylase<br />

232 Th stable isotope <strong>of</strong> thorium-232<br />

TLC Treatment <strong>of</strong> <strong>Lead</strong>-exposed Children (study)<br />

TNF tumor necrosis factor (e.g., TNF-α)<br />

TOF time-<strong>of</strong>-flight<br />

tPA plasminogen activator<br />

TPRD total production<br />

TRH thyroid releasing hormone<br />

TRV toxicity reference value<br />

TSH thyroid stimulating hormone<br />

TSP triple-super phosphate<br />

TT3 total triiodothyronine<br />

TT4 serum total thyroxine<br />

TTES total testosterone<br />

TTR transthyretin<br />

TU toxic unit<br />

TWA time-weighted average<br />

TX tromboxane (e.g., TXB2)<br />

U uriniary<br />

235 238<br />

U, U uranium-234 and -238 radionuclides<br />

UCP urinary coproporphyrin<br />

UDP uridine diphosphate<br />

UNECE United Nations Economic Commission <strong>for</strong> Europe<br />

Ur urinary<br />

<strong>US</strong>FWS U.S. Fish and Wildlife Service<br />

<strong>US</strong>GS United States Geological Survey<br />

UV ultraviolet<br />

V79 Chinese hamster lung cell line<br />

VA Veterans Administration<br />

VC vital capacity; vitamin C<br />

VDR vitamin D receptor<br />

VE vitamin E<br />

VEP visual-evoked potential<br />

VI<br />

variable-interval<br />

<strong>II</strong>-xlix


vit C vitamin C<br />

vit E vitamin E<br />

VMA vanilmandelic acid<br />

VMI Visual-Motor Integration<br />

VSM vascular smooth muscle (cells)<br />

VSMC vascular smooth muscle cells<br />

WAIS Wechsler Adult Intelligence Scale<br />

WDS wavelength dispersive spectrometers<br />

WHO World Health Organization<br />

WISC Wechsler Intelligence Scale <strong>for</strong> Children<br />

WISC-R Wechsler Intelligence Scale <strong>for</strong> Children-Revised<br />

WO whole organism<br />

WRAT-R Wide Range Achievement Test-Revised<br />

WT wild type<br />

WTHBF-6 human liver cell line<br />

ww wet weight<br />

XAFS X-ray absorption fine structure<br />

XANES X-ray absorption near edge spectroscopy<br />

XAS X-ray absorption spectroscopy<br />

XPS X-ray photoelectron spectroscopy<br />

X-rays synchrotron radiation<br />

XRD X-ray diffraction<br />

XRF X-ray fluorescence<br />

ZAF correction in reference to three components <strong>of</strong> matrix effects:<br />

atomic number (Z), absorption (A), and fluorescence (F)<br />

ZnNa2 DTPA zinc disodium diethylenetriaminepentaacetic acid<br />

ZnNa2 EDTA zinc disodium ethylenediaminetetraacetic acid<br />

ZPP zinc protoporphyrin<br />

<strong>II</strong>-l


AX4. CHAPTER 4 ANNEX<br />

ANNEX TABLES AX4<br />

AX4-1


AX4-2<br />

Table AX4-1. Analytical Methods <strong>for</strong> Determining <strong>Lead</strong> in Blood, Urine, and Hair<br />

Sample<br />

Matrix Preparation Method Analytical Method<br />

Blood Wet ashing with acid mixtures; residue dissolution in<br />

dilute HClO 4<br />

Blood Wet ashing with HNO3; residue dissolution in dilute<br />

HNO3<br />

Blood Dilution with Triton X-100 ® ; addition <strong>of</strong> nitric acid<br />

and diammonium phosphate<br />

Blood Dilution <strong>of</strong> sample with ammonium solution<br />

containing Triton X-100<br />

ASV with mercurygraphite<br />

electrode<br />

(NIOSH Method 195)<br />

GFAAS<br />

(NIOSH Method 214)<br />

Sample<br />

Detection Limit<br />

Accuracy<br />

(percent recovery) Reference<br />

40 µg/L 95B105 NIOSH (1977b)<br />

100 µg/L No data NIOSH (1977e)<br />

GFAAS 2.4 µg/L 93B105 Aguilera de Benzo<br />

et al. (1989)<br />

ICP/MS 15 µg/L 96B111 Delves and Campbell<br />

(1988)<br />

Blood Dilution <strong>of</strong> sample in 0.2% Triton X-100 and water GFAAS .15 µg/L 97B150 Que Hee et al. (1985)<br />

Blood Wet ashing, dilution<br />

Blood and<br />

urine<br />

Blood and<br />

urine<br />

Blood and<br />

urine<br />

Blood and<br />

tissue<br />

Mixing <strong>of</strong> urine sample with HNO3; filtration,<br />

chelation <strong>of</strong> lead in whole blood or filtered urine with<br />

APDC, extraction with MIBK<br />

Wet ashing <strong>of</strong> sample with HNO 3, complexation<br />

with diphenylthio-carbazone, and extraction with<br />

chloro<strong>for</strong>m<br />

206 Pb addition and sample acid digestion; lead<br />

coprecipitation by addition <strong>of</strong> Ba(NO3) 2, followed by<br />

electrodeposition on platinum wire<br />

ICP-MS 0.1 ppb 94B100<br />

GFAAS 4 ppb 90B108<br />

AAS<br />

(NIOSH Method 8003)<br />

Spectrophotometry<br />

(NIOSH Method 102)<br />

0.05 µg/g (blood);<br />

50 µg/L (urine)<br />

30 µg/L (blood);<br />

12 µg/L (urine)<br />

Zhang et al. (1997)<br />

99 (±10.8%) NIOSH (1994)<br />

97<br />

97<br />

NIOSH (1977a)<br />

IDMS No data 98B99 Manton and Cook<br />

(1984)<br />

Digestion <strong>of</strong> sample with HNO3/HClO4 /H2SO4; heat ICP-AES (Method 8005) 0.01 µg/g (blood);<br />

0.2 µg/g (tissue)<br />

113 NIOSH (1984)


AX4-3<br />

Table AX4-1 (cont’d). Analytical Methods <strong>for</strong> Determining <strong>Lead</strong> in Blood, Urine, and Hair<br />

Sample<br />

Matrix Preparation Method Analytical Method<br />

Blood Addition <strong>of</strong> 50 µL <strong>of</strong> blood into reagent, mixing,<br />

and transferring to sensor strip (commercial test kit)<br />

Urine Collect 50 mL urine sample and add 5 mL<br />

concentrated HNO3 as preservative; filter samples<br />

through cellulose membrane, adjust pH to 8, ash filters<br />

and resins in low temperature oxygen plasma <strong>for</strong><br />

6 hours<br />

Serum,<br />

blood, and<br />

urine<br />

Filtration <strong>of</strong> sample if needed; blood requires<br />

digestion in a Parr bomb; dilution <strong>of</strong> serum or urine<br />

with acid or water<br />

Urine Wet ashing <strong>of</strong> sample with acid mixture and<br />

dissolution in dilute HClO 4<br />

Hair Cleaning <strong>of</strong> sample with acetone/ methanol; digestion<br />

with acid mixture and heat; diammonium phosphate<br />

addition as matrix modifier<br />

Hair Cleaning with lauryl sulfate and water; digestion with<br />

heated nitric acid<br />

Hair Cleaning with water; digestion with heated nitric acid<br />

and H2O 2<br />

Sample<br />

Detection Limit<br />

Accuracy<br />

(percent recovery) Reference<br />

Gold electrode sensor 1.4 µg/dL No data ESA (1998)<br />

ICP-AES (Method 8310) 5 µg/L 100 NIOSH (1994)<br />

ICP-AES 10B50 µg/L 85 (serum) >80<br />

(urine, blood)<br />

ASV with mercurygraphite<br />

electrode<br />

(Method 200)<br />

Que Hee and Boyle<br />

(1988)<br />

4 µg/L 90B110 NIOSH (1977c)<br />

GFAAS 0.16 µg/g 99 Wilhelm et al. (1989)<br />

ICP-AES 1 µg/g No data DiPietro et al. (1989)<br />

ET-AAS 90 Drash et al. (1997)<br />

Hair Cleaning with acetone/water XRF 0.5 µg/g No data Gerhardsson et al.<br />

(1995a)<br />

AAS, atomic absorption spectroscopy; APDC, ammonium pyrrolidine dithiocarbamate; ASV, anode stripping voltammetry; Ba(NO 3) 2, barium nitrate; ET-AAS, electro-thermal<br />

atomic absorption spectrometry; GFAAS, graphite furnace atomic absorption spectroscopy; H2O 2, hydrogen peroxide; H 2SO 4, sulfuric acid; HClO 4, perchloric acid; HNO 3,<br />

nitric acid; ICP-AES, inductively coupled plasma/atomic emission spectroscopy; ICP-MS, inductively coupled plasma-mass spectrometry; IDMS, isotope dilution mass<br />

spectrometry; MIBK, methyl isobutyl ketone; NIOSH, National Institute <strong>for</strong> Occupational Safety and Health; 206 Pb, lead 206; XRF, X-ray fluorescence.


AX4-4<br />

Table AX4-2. Summary <strong>of</strong> Selected Measurements <strong>of</strong> PbB Levels in Humans<br />

Reference, Study<br />

Location, and Period Study Description PbB Measurement Comment<br />

United States<br />

CDC (2005)<br />

U.S.<br />

1999-2002<br />

Brody et al. (1994)<br />

Pirckle et al. (1998)<br />

U.S.<br />

1988-1994<br />

Design: National survey (NHANES IV)<br />

stratified, multistage probability cluster design<br />

Subjects: Children and adults ($1 yrs, n = 16, 915)<br />

in general population<br />

Biomarker measured: PbB<br />

Analysis: ICP-MS<br />

Design: National survey (NHANES <strong>II</strong>I)<br />

stratified multistage probability cluster design.<br />

Subjects: Children and adults ($1 yrs, n = 29, 843)<br />

in general population<br />

Biomarker measured: PbB<br />

Analysis: GFAAS<br />

Units: µg/dL<br />

Geometric mean (95% CI)<br />

Age (yr) 1999-2000 2001-2002<br />

1-5: 1.66 (1.60, 1.72) 1.45 (1.39, 1.40)<br />

n: 7, 970 8, 945<br />

6-11: 1.51 (1.36, 1.66) 1.25 (1.14, 1.36)<br />

n: 905 1,044<br />

12-19: 1.10 (1.04, 1.17) 0.94 (0.90, 0.99)<br />

n: 2, 135 2, 231<br />

$20: 1.75 (1.68, 1.81) 1.56 (1.49, 1.62)<br />

n: 4, 207 4, 772<br />

Males: 2.01 (1.93, 2.09) 1.78 (1.71, 1.86)<br />

n: 3, 913 4, 339<br />

Females: 1.37 (1.32, 1.43) 1.19 (1.14, 1.25)<br />

n: 4,057 4, 606<br />

Units: µg/dL<br />

Geometric mean (95% CI)<br />

Age (yr) 1988-1991 1991-1994<br />

1-5: 3.6 (3.3, 4.0) 2.7 (2.5, 3.0)<br />

n: 2, 234 2, 392<br />

6-11: 2.5 (2.2, 2.7) 1.9 (1.8, 2.1)<br />

n: 1, 587 1, 345<br />

12-19: 1.6 (1.4, 1.9) 1.5 (1.4, 1.7)<br />

n: 1, 376 1, 615<br />

20-49: 2.6 (2.5, 2.8) 2.1 (2.0, 2.2)<br />

n: 4, 320 4, 716<br />

50-69 4.0 (3.8, 4.2) 3.1 (2.9, 3.2)<br />

n: 2,071 2,026<br />

$70 4.0 (3.7, 4.3) 3.4 (3.3, 3.6)<br />

n: 1, 613 1, 548<br />

Males: 3.7 (3.5, 3.9) 2.8 (2.6, 2.9)<br />

n: 6,051 6, 258<br />

Females: 2.1 (2.0, 2.2) 1.9 (1.8, 2.)<br />

n: 6,068 7, 384<br />

Data from NHANES IV Phase 1<br />

(1999-2000) and 2 (2001-2002).<br />

Comparison <strong>of</strong> data from NHANES <strong>II</strong>I<br />

Phase 1 (1988-1991) and Phase 2<br />

(1991-1994) indicated declining PbB<br />

concentrations in children.


AX4-5<br />

Table AX4-2 (cont’d). Summary <strong>of</strong> Selected Measurements <strong>of</strong> PbB Levels in Humans<br />

Reference, Study<br />

Location, and Period Study Description PbB Measurement Comment<br />

United States (cont’d)<br />

Nash et al. (2003)<br />

U.S.<br />

1988-1994<br />

Pirkle et al. (1994)<br />

U.S.<br />

1976-1980<br />

Symanski and Hertz-<br />

Picciotto (1995)<br />

U.S.<br />

1982-1984<br />

Design: National survey (NHANES <strong>II</strong>I) stratified,<br />

multistage probability cluster design<br />

Subjects: Women(n = 2, 575), age range:<br />

40-59 yrs, in general population<br />

Biomarker measured: PbB<br />

Analysis: GFAAS<br />

Design: National survey (NHANES <strong>II</strong>, <strong>II</strong>I)<br />

stratified, multistage probability cluster design<br />

Subjects: Children and adults ($1 yrs, n = 29, 843)<br />

in general population<br />

Biomarker measured: PbB<br />

Analysis: GFAAS<br />

Design: National survey (HHANES) multistagearea<br />

probability sample<br />

Subjects: Adults, females (n = 3, 137), age range<br />

20-60 yrs, in general Hispanic population<br />

Biomarker measured: PbB<br />

Analysis: GFAAS<br />

Units: µg/dL<br />

Geometric mean (95% CI, n)<br />

Premenopausal: 1.9 (1.7, 2.0, 1, 222)<br />

Surgically menopausal: 2.7 (2.4, 3.2, 139)<br />

Naturally menopausal: 2.9 (2.5, 3.2, 653)<br />

Units: µg/dL<br />

Geometric mean (95% CI)<br />

Age (yr) 1976-1980 1988-1991<br />

1-5: 15.0 (14.2, 15.8) 3.6 (3.3, 4.0)<br />

n: 2, 271 2, 234<br />

6-19: 11.7 (11.2, 12.4) 1.9 (1.7, 2.2)<br />

n: 2,024 2, 963<br />

20-74: 13.1 (12.7, 13.7) 3.0 (2.8, 3.2)<br />

n: 5, 537 6, 922<br />

Males: 15.0 (14.5, 15.5) 3.7 (3.5, 3.9)<br />

n: 4, 895 6,051<br />

Females: 11.1 (10.6, 11.5) 2.1 (2.0, 2.2)<br />

n: 4, 937 6,068<br />

Units: µg/dL<br />

Arithmetic mean (SE, n)<br />

All<br />

Premenopausal: 7.5 (0.07, 1, 984)<br />

Menopausal: 8.9 (0.11, 1, 152)<br />

Mexican-American:<br />

Premenopausal: 7.2 (0.13, 1, 219)<br />

Menopausal: 8.4 (0.20, 624)<br />

Geometric mean PbB concentrations<br />

were significantly lower in<br />

premenopausal women. Increasing<br />

PbB concentrations were significantly<br />

associated with decreased bone mineral<br />

density.<br />

Comparison <strong>of</strong> data from NHANES <strong>II</strong><br />

(1976-1980) and Phase 1 <strong>of</strong> NHANES<br />

<strong>II</strong>I (1988-1991) indicated declining<br />

PbB concentrations in U.S. population.<br />

Mean difference between<br />

premenopausal and postmenopausal<br />

(#4 yrs) was 1.4 µg/dL<br />

(95% CI: 0.20, 2.7).


AX4-6<br />

Table AX4-2 (cont’d). Summary <strong>of</strong> Selected Measurements <strong>of</strong> PbB Levels in Humans<br />

Reference, Study<br />

Location, and Period Study Description PbB Measurement Comments<br />

United States (cont’d)<br />

Yassin et al. (2004)<br />

U.S.<br />

1988-1994<br />

Mexico<br />

Hernandez-Avila et al.<br />

(2002)<br />

Mexico<br />

1993-1995<br />

Design: National survey (NHANES <strong>II</strong>I) stratified,<br />

multistage probability cluster design<br />

Subjects: Adults (n = 11, 126) in general<br />

population, age range: 18-64 yr), stratified by<br />

occupational category<br />

Biomarker measured: PbB<br />

Analysis: GFAAS<br />

Design: Cross-sectional<br />

Subjects: Adults females (n = 903) in general<br />

population, age range: 36-70 yr<br />

Biomarker measured: PbB<br />

Analysis: GFAAS<br />

Units: µg/dL<br />

Occupation GM GSD Maximum n<br />

Vehicle mechanics 4.80 3.88 28.1 169<br />

Food service workers<br />

Management, pr<strong>of</strong>essional<br />

2.00 2.69 27.0 700<br />

technical, and sales workers 2.13 4.05 39.4 4, 768<br />

Personal service workers 2.48 4.52 25.9 1, 130<br />

Agricultural workers<br />

Production workers: machine<br />

2.76 4.02 23.4 498<br />

operators, material movers, etc. 2.88 4.24 52.9 1, 876<br />

Laborers other than in construction 3.47 3.36 21.8 137<br />

Transportation workers<br />

Mechanics other than vehicle<br />

3.49 5.19 22.3 530<br />

mechanics 3.50 4.91 16.6 227<br />

Construction trades people 3.66 4.64 16.9 470<br />

Construction laborers 4.44 7.84 36.0 122<br />

Health service workers 1.76 2.24 22.4 499<br />

All 2.42 6.93 52.9 11, 126<br />

Units: µg/dL<br />

Arithmetic mean (SD, n)<br />

Premenopausal: 10.63 (5.46, 463)<br />

Menopausal: 11.39 (2.65, 437)<br />

Surgically menopausal: 10.23 (4.92, 115)<br />

Naturally menopausal: 11.30 (5.88, 322)<br />

PbB, blood lead; GFAAS, graphite furnace atomic absorption spectroscopy; ICP-MS, inductively coupled plasma-mass spectrometry; NR, not reported.<br />

Mean difference between<br />

premenopausal and menopausal; was<br />

0.76 µg/dL (95% CI: 0.224, 1.48).


AX4-7<br />

Table AX4-3. Bone <strong>Lead</strong> Measurements in Cadavers<br />

Reference, Study<br />

Location, and Period Study Description <strong>Lead</strong> Measurement Findings, Interpretation<br />

United States<br />

Wittmers et al. (1988)<br />

Minnesota<br />

1976-82<br />

Saltzman et al. (1990)<br />

Cincinnati, OH<br />

1970-71<br />

Canada<br />

Samuels et al. (1989)<br />

Canada<br />

1965-69<br />

<strong>Lead</strong> in tibia, skull, iliac crest, rib,<br />

and vertebrae. 81 Caucasian males<br />

and 53 male cadavers ranging in age<br />

from 0 to 98 yr. Ashing, nitric acid,<br />

AAS.<br />

29 tissues from 55 cadavers, mean<br />

age 50 yrs. Muffle furnace ashing.<br />

Pb concentrations by dithazone<br />

method.<br />

Ashed vertebral bones from male<br />

and female cadavers from three<br />

Canadian cities. AAS method.<br />

Mean and SEM (µg/g bone ash) >75 yr: Tibia 29.0 ±3.4 (n = 28), ilium<br />

17.0 ± 2.6 (n = 29), rib 20.5 ± 2.4 (n = 31), vertebra 18.8 ± 2.6 (n = 30),<br />

skull 26.1 ± 3.2 (n = 28)<br />

51-75 yr: Tibia 24.2 ± 2.3 (n = 38), ilium 19.2 ± 2.4 (n = 15), rib 22.3 ± 2.6<br />

(n = 40), vertebra 22.4 ± 2.6 (n = 41), skull 22.8 ± 2.9 (n = 29)<br />

36-50 yr: Tibia 16.6 ±4.1 (n = 14), ilium 9.9 ± 1.6 (n = 15), rib 9.7 ± 1.7<br />

(n = 15), vertebra 11.9 ± 2.1 (n = 15), skull 15.2 ± 3.3 (n = 15)<br />

21-35 yr: Tibia 5.9 ±1.2 (n = 18), ilium 5.3 ± 1.2 (n = 16), rib 5.0 ± 1.2<br />

(n = 18), vertebra 6.3 ± 1.3 (n = 17), skull 4.9 ± 1.1 (n = 17)<br />

14-20 yr: Tibia 2.3 ±1.0 (n = 13), ilium 2.3 ± 0.9 (n = 13), rib 2.9 ± 1.4<br />

(n = 12), vertebra 3.8 ± 1.4 (n = 12), skull 3.2 ± 1.7 (n = 10)<br />

0-2 yr: Tibia 0.3 ±0.2 (n = 11), ilium 0.0 ± 0.0 (n = 11), rib 0.7 ± 0.4<br />

(n = 12), vertebra 0.6 ± 0.6 (n = 12), skull 0.6 ± 0.4 (n = 12)<br />

Higher concentrations <strong>of</strong> Pb in tibia compared with rib and vertebrae and<br />

higher values <strong>for</strong> males compared with females. Males (n = 46): Ribs<br />

6.70 ± 3.96 (µg/g, wet weight), tibia 12.55 ± 10.65, vertebrae 4.12 ± 2.49.<br />

Females (n = 8): Ribs 3.17 ± 0.91 (µg/g, wet weight), tibia 4.54 ± 2.04,<br />

vertebrae 2.01 ± 0.72.<br />

Changes <strong>for</strong> different age ranges in Pb concentration <strong>for</strong> the period<br />

1965-1969:<br />

0-11 months: 3.98 µg/g (n = 28)<br />

1-4 yrs: 10.02 µg/g (n = 32)<br />

5-11 yrs: 12.91 µg/g (n = 26)<br />

12-19 yrs: 7.11 µg/g (n = 26)<br />

$20 yrs: 14.77 µg/g (n = 25)<br />

Ratio <strong>of</strong> lead in tibia and<br />

skull/iliac/rib/vertebrae<br />

1 from 36 to 75 yrs and<br />

greater than 75 yrs. Evidence<br />

<strong>of</strong> differential distribution<br />

amongst bones with age; the<br />

earliest difference is apparent<br />

during adolescence when<br />

trabecular bone <strong>of</strong> the<br />

vertebral body accumulates<br />

significantly more lead than<br />

that <strong>of</strong> the other 4 sites.<br />

Bone Pb increased with age.<br />

Results were similar to those<br />

<strong>of</strong> Barry (1978) and Wittmers<br />

et al. (1988).<br />

For period 1965 to 1969<br />

levels vary over age groups<br />

(p = 0.0001) but there was<br />

little gender difference. For<br />

the period 1980 to 1998 <strong>for</strong><br />

Winnipeg, values were<br />

approximately half to one<br />

third those prevailing earlier.


AX4-8<br />

Table AX4-3 (cont’d). Bone <strong>Lead</strong> Measurements in Cadavers<br />

Reference, Study<br />

Location, and Period Study Description <strong>Lead</strong> Measurement Findings, Interpretation<br />

Europe<br />

Drasch et al. (1987)<br />

Germany<br />

1983-85<br />

Drasch and Ott (1988)<br />

Germany<br />

1984<br />

Hac et al. (1997)<br />

Poland<br />

Asia<br />

Noda et al. (1993)<br />

Japan<br />

1976, 1981, and 1986<br />

Bone Pb in temporal<br />

bone, cortical part <strong>of</strong><br />

the mid-femur, and<br />

pelvic bone from<br />

120 female and 120<br />

male adult cadavers.<br />

AAS.<br />

Bone Pb in temporal<br />

bone, cortical part <strong>of</strong><br />

the mid femur, and<br />

pelvic bone from<br />

82 child cadavers.<br />

Nitric acid digestion,<br />

AAS.<br />

Pb in rib bone and hair<br />

from 59 cadavers, aged<br />

1-87 yrs. Perchloric<br />

acid digestion, AAS.<br />

76 cadavers, age range<br />

0 to 83 yrs.<br />

Geometric means:<br />

Males: Pelvic 1.95 ± 1.00 (µg/g, wet weight), mid-femur 4.75 ± 2.53, temporal 6.24 ± 3.17.<br />

Females: Pelvic 1.41 ± 0.74 (µg/g), mid-femur 3.14 ± 1.89, temporal 5.00 ± 2.66.<br />

Age 0-1 yrs 1-6 yrs 10-20 yrs 0-20 yrs<br />

Sex Male Female Male Female Male Female Male Female<br />

n 9 16 9 9 18 16 39 42<br />

Temporal 0.331 0.334 0.530 0.732 1.770 1.740 0.858 0.749<br />

Pelvic<br />

bone<br />

0.230 0.278 0.461 0.522 0.748 0.511 0.455 0.404<br />

Mid-femur 0.333 0.327 0.642 0.858 1.342 1.010 0.768 0.632<br />

(values in µg/g wet weight)<br />

Found cortical lead ><br />

trabecular lead. Limited<br />

difference in Pb <strong>for</strong> younger<br />

males and females; much<br />

higher Pb in bones <strong>of</strong> men<br />

>50 yr old compared with<br />

women<br />

Negligible difference <strong>for</strong> 0 to<br />

1 yr olds, <strong>for</strong> pre-school<br />

children (1-6 yrs) and <strong>for</strong><br />

10 to 20 yr olds; mean values<br />

<strong>for</strong> cortical bones showed<br />

higher Pb concentrations than<br />

trabecular bone; mean Pb in<br />

the mid femur and temporal<br />

bone was not statistically<br />

different <strong>for</strong> each <strong>of</strong> three<br />

age groups.<br />

Bone Pb 3.0 (±1.5) µg/g (n = 54). Small increases to age 50 yrs<br />

in rib bone. Number <strong>of</strong><br />

samples <strong>for</strong> each age group<br />

not stated.<br />

Age 0 yrs (1.25 µg/g wet weight) to 59 yrs (4.5 µg/g) after which there was a decrease<br />

(~2.5 µg/g). For the age range 10-49 yrs, there was no significant difference in mean<br />

values <strong>of</strong> 2.8 to 3.1 µg/g.<br />

Found no significant gender<br />

difference but levels in 1986<br />

were significantly lower than<br />

in 1976.


AX4-9<br />

Reference, Study<br />

Location, and Period Study Description<br />

United States<br />

Kim et al. (1996)<br />

Boston, MA<br />

1989-90<br />

Hu et al. (1990)<br />

Boston, MA<br />

Unknown<br />

Hu et al. (1996)<br />

Boston, MA<br />

1991+<br />

Campbell et al. (2004)<br />

New York<br />

Unknown<br />

Table AX4-4. Bone <strong>Lead</strong> Measurements in Environmentally-Exposed Subjects<br />

Examination <strong>of</strong> the relationship between<br />

tooth Pb in children and bone Pb levels<br />

in young adults. Members <strong>of</strong> a cohort <strong>of</strong><br />

young adults (n = 63, ~20 yr <strong>of</strong> age) were<br />

reassessed 13 yr after initial examination.<br />

Dentine Pb by anodic stripping voltammetry.<br />

Bone K-shell XRF. LOWESS smoothing,<br />

multiple linear regression.<br />

To evaluate if K-shell XRF can be used to<br />

assess low-level Pb burdens in 34 employees<br />

(26 males, 8 females) ranging in age from 21<br />

to 58 yr <strong>of</strong> a biomedical company with no<br />

known history <strong>of</strong> excessive Pb exposure.<br />

Medical environmental history<br />

questionnaire. Multiple linear regression.<br />

Normative Aging Study.<br />

Subjects were middle-aged and elderly men<br />

who had community (nonoccupational)<br />

exposures to lead.<br />

Cross-sectional. Backwards elimination<br />

multivariate regression models that<br />

considered age, race, education, retirement<br />

status, measures <strong>of</strong> both current and<br />

cumulative smoking, and alcohol<br />

consumption.<br />

Investigated the relationship between bone<br />

mineral density and environmental Pb<br />

exposure in 35 African American children.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

No PbB.<br />

Tibia Pb 1.3 (± 4.4), patella Pb 5.4 (±8.4).<br />

Dentine Pb 13.4 (±10.7).<br />

Approximately one-third <strong>of</strong> tibia and one-fourth<br />

<strong>of</strong> patella estimates were negative values.<br />

18 (53%) <strong>of</strong> subjects had bone Pb levels included<br />

0 or less within the estimate <strong>of</strong> uncertainty.<br />

Highest bone Pb 21 ± 4 µg/g bone mineral.<br />

For 16 young adults, age and year <strong>of</strong> home<br />

construction had a positive but statistically<br />

insignificant effect (p > 0.05) on bone Pb.<br />

47-59 yrs (n = 116): PbB 5.8 (±3.7), tibia 14.6<br />

(±8.3), patella 23.6 (±12.4)<br />

60-69 yrs (n = 360): PbB 6.3 (±4.2), tibia 21.1<br />

(±11.4), patella 30.5 (±16.9)<br />

>70 yrs (n = 243): PbB 6.5 (±4.5), tibia 27<br />

(±15.6), patella 38.8 (±23.5)<br />

High Pb exposure: PbB levels (mean 23.6 µg/dL;<br />

n = 19); low Pb exposure (mean 6.5 µg/dL;<br />

n = 16).<br />

A 10 µg/g increase in dentine Pb levels in<br />

childhood was predictive <strong>of</strong> a 1 µg/g increase<br />

in tibia Pb levels and a 5 µg/g increase in<br />

patella PbB levels, and a 3 µg/g increase in<br />

mean bone Pb levels among the young adults.<br />

They concluded that Pb exposure in early life<br />

may be used to predict elevated body burden<br />

up to 13 yr later.<br />

K-shell XRF may be useful <strong>for</strong> assessing lowlevel<br />

Pb burdens in epidemiological studies.<br />

Factors that remained significantly related to<br />

higher levels <strong>of</strong> both tibia and patella Pb were<br />

higher age and measures <strong>of</strong> cumulative<br />

smoking, and lower levels <strong>of</strong> education.<br />

An increase in patella Pb from the median <strong>of</strong><br />

the lowest to the median <strong>of</strong> the highest<br />

quintiles (13-56 µg/g) corresponded to a rise<br />

in PbB <strong>of</strong> 4.3 µg/dL. Bone Pb levels<br />

comprised the major source <strong>of</strong> circulating lead<br />

in these men.<br />

Unexpectedly, they found that children with<br />

high Pb exposure had a significantly higher<br />

bone mineral density than children with low<br />

Pb exposure. They hypothesized that this<br />

arises from the effect <strong>of</strong> Pb on accelerating<br />

bone maturation by inhibition <strong>of</strong> parathyroid<br />

hormone-related peptide.


AX4-10<br />

Table AX4-4 (cont’d). Bone <strong>Lead</strong> Measurements in Environmentally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

United States (cont’d)<br />

Rosen et al.<br />

(1989)<br />

Bronx, NY<br />

Unknown<br />

Kosnett et al. (1994)<br />

Dickson City, PA<br />

1991<br />

Rosen et al. (1993)<br />

Moosic and Throop, PA<br />

1989-91<br />

Stokes et al. (1998)<br />

Bunker Hill, ID; Spokane,<br />

WA<br />

1994<br />

Comparison <strong>of</strong> L-shell XRF measures<br />

and EDTA provocation test in lead-toxic<br />

children 1-6 yr old. Eligible if PbB 25-<br />

55 µg/dL and erythrocyte protoporphyrin<br />

>35 µg/dL.<br />

Aim to determine the influence <strong>of</strong><br />

demographic, exposure and medical<br />

factors on the bone Pb concentration <strong>of</strong><br />

subjects with environmental Pb exposure.<br />

101 subjects (49 males, 52 females; aged<br />

11 to 78 yrs) recruited from 49 <strong>of</strong> 123<br />

households geographically located in a<br />

suburban residential neighborhood.<br />

Tibia. Multiple regression.<br />

Suburban population (Throop, n = 269)<br />

exposed to unusually high emissions<br />

during 1963-81 from nearby battery<br />

recycling/secondary smelter. Moosic<br />

served as control community.<br />

Approximately 9% children aged 5-12 yr,<br />

15% 13-17 yr, 40% ≥ 18 yr. Soil and<br />

PbB, L-shell XRF.<br />

Examined whether environmental<br />

exposure to Pb during childhood was<br />

associated with current adverse<br />

neurobehavioral effects. K-shell XRF.<br />

Formerly exposed as children 19-30 yr<br />

(n = 238, age 19-30 yr).<br />

Referents (n = 258)<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Negative EDTA test results (n = 30): PbB 30 ± 5<br />

µg/dL, tibia Pb 12 ± 2 µg/g (range 7-52).<br />

Positive EDTA test results (n = 29): PbB 39 ± 8<br />

µg/dL, tibia Pb 37 ± 3 µg/g (range 7-200).<br />

Mean (SD) bone Pb12.7 (14.6).<br />

Log-trans<strong>for</strong>med bone Pb highly correlated with<br />

age (r = 0.71; p # 0.0001). Gender differences in<br />

log-trans<strong>for</strong>med bone Pb values were<br />

insignificant up until the 6 th decade.<br />

No significant differences in tibia Pb found<br />

among three age groups in Moosic or Throop.<br />

Mooaic: means 5-12 yr, 6 µg/g; 13-17 yr, 8 µg/g;<br />

$18 yr, 7 µg/g<br />

Throop: means 5-12 yr, 12 ± 1 µg/g; 13-17 yr,<br />

15 ± 2 µg/g; $18 yr, 12 ± 1 µg/g.<br />

Exposed group:<br />

PbB 2.9 µg/dL; tibia Pb 4.6 µg/g.<br />

Referent group:<br />

PbB 1.6 µg/dL; tibia Pb 0.6 µg/g.<br />

From PbB and LXRF alone, 90% <strong>of</strong> Pb-toxic<br />

children were correctly classified as being<br />

EDTA-positive or -negative. LXRF may be<br />

capable <strong>of</strong> replacing EDTA testing.<br />

Bone Pb showed no significant change up to<br />

age 20 yr, increased with the same slope in<br />

men and women between ages 20 and 55 yrs,<br />

and then increased at a faster rate in men older<br />

than 55 yrs.<br />

No change in bone Pb with age. Baseline<br />

values <strong>for</strong> bone Pb in the environmentally<br />

exposed population <strong>of</strong> Moosic can serve as a<br />

reference baseline <strong>for</strong> contemporary bone Pb<br />

levels in similar communities in the <strong>US</strong>A.


AX4-11<br />

Table AX4-4 (cont’d). Bone <strong>Lead</strong> Measurements in Environmentally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

United States (cont’d)<br />

McNeill et al. (2000)<br />

Idaho and Washington<br />

1994<br />

Mexico<br />

Farias et al. (1998)<br />

Mexico City and suburbs<br />

1995-96<br />

PbB = blood lead.<br />

To determine if high Pb exposure in<br />

childhood persisted until adulthood.<br />

262 exposed subjects and 268 age and<br />

sex matched controls aged 19 – 29 yr.<br />

Tibia bone Pb, cumulative PbB index.<br />

Inverse weighted group mean data,<br />

linear regressions.<br />

Examined the relation <strong>of</strong> blood and<br />

tibia bone Pb levels to Pb<br />

determinants in 100 adolescents aged<br />

11 to 21 yr. LOWESS smoothing,<br />

multivariate regressions.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Group inverse weighted mean (SEM).<br />

Males: Exposed 4.54 (0.31); controls 0.03 (0.31) µg<br />

Pb/g bone mineral.<br />

Females: Exposed 5.61 (0.43); controls 1.67 (0.43)<br />

µg Pb/g bone mineral.<br />

Females (n = 62): PbB 6.4 (±3.2), tibia 5.5(±8.6).<br />

Males (n = 36): PbB 9.1 (±5.5), tibia 3.8 (±5.5).<br />

25 subjects had bone Pb < 0.<br />

Bone Pb accounted <strong>for</strong> 4.1% <strong>of</strong> variation in PbB.<br />

Increase in bone Pb <strong>of</strong> 21.6 µg/g was associated with<br />

an increase in PbB <strong>of</strong> 1.2 µg/dL.<br />

<strong>Lead</strong> from exposure in early childhood had<br />

persisted in the bone matrix until adulthood.<br />

Bone Pb significantly correlated with age <strong>for</strong><br />

exposed groups. No significant correlation in<br />

regressions <strong>for</strong> control groups with age.<br />

Exposed subjects had group bone Pb levels<br />

significantly higher (p < 0.005) than control<br />

subjects in 7 <strong>of</strong> 11 age groups. Exposed<br />

subjects had increased current PbB<br />

concentrations that correlated significantly<br />

with bone Pb values. Incorporation rate <strong>of</strong> Pb<br />

into bone 0.039 (0.003) (Fg Pb/g bone<br />

mineral)/ µg/dL yr).<br />

Predictors <strong>of</strong> bone Pb included higher traffic<br />

density near the home, mother's smoking<br />

history, and time spent outdoors. Predictors<br />

<strong>of</strong> log-trans<strong>for</strong>med PbB included bone Pb<br />

levels, male sex, use <strong>of</strong> Pb-glazed ceramics,<br />

and living in Mexico City. Bone Pb<br />

accumulated over time constitutes a moderate<br />

source <strong>of</strong> circulating Pb during adolescence


AX4-12<br />

Reference, Study<br />

Location, and Period Study Description<br />

United States<br />

Hu et al. (1994)<br />

U.S.<br />

1991<br />

Schwartz et al. (2000b)<br />

U.S.<br />

1995<br />

Popovich et al. (2005)<br />

Idaho<br />

Canada<br />

Fleming et al. (1997)<br />

Canada<br />

1994<br />

Table AX4-5. Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Construction workers aged 23 to 67 yr<br />

(n = 19). Examination <strong>of</strong> Bone Pb<br />

and PbB as predictors <strong>of</strong> blood<br />

pressure in construction workers.<br />

Multivariate linear regression,<br />

LOWESS smoothing.<br />

Retired organolead employees (n =<br />

543). Aim to determine influence <strong>of</strong><br />

PbB, chelatable Pb, and tibial Pb on<br />

systolic and diastolic blood pressure.<br />

108 <strong>for</strong>mer female smelter employees<br />

and 99 referents to assess the PbB<br />

versus bone Pb relationship.<br />

Primary smelter workers, 367 active<br />

and 14 retired.<br />

PbB in 204 workers returning after a<br />

10-mo strike ended in 1991.<br />

Cumulative PbB index, K-shell<br />

measures with 109 Cd source.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

PbB 8.3 (±4.0), tibia Pb 9.8 (±9.5), patella Pb<br />

13.9 (±13.6).<br />

PbB 4.6 (±2.6), tibia Pb14.4 (±9.3). Tibia Pb was not associated with any blood<br />

pressure measures.<br />

Exposed: PbB 2.73 (±2.39), tibia 14.4 (±0.5)<br />

Referents: PbB 1.25 (±2.10), tibia 3.22 (±0.50)<br />

Pb concentrations in tibia and blood significantly<br />

higher in the exposed group. Endogenous release<br />

rate (µg Pb per dL blood/µg Pb/g bone) in<br />

postmenopausal women was double the rate found in<br />

premenopausal women (0.132 ± 0.019 vs. 0.067 ±<br />

0.014).<br />

Active (1975-81) median PbB 16.0, (1987-92)<br />

median PbB 8.0, tibia range 0-150, calcaneus 0-250.<br />

Retired tibia range 20-120, calcaneus 40-220.<br />

Bone Pb-cumulative PbB index slopes larger <strong>for</strong><br />

retired compared with active workers, but not<br />

significant.<br />

Higher tibia bone Pb (and PbB) was<br />

associated with use <strong>of</strong> estrogen (present or<br />

<strong>for</strong>mer) in both the whole referent group and<br />

postmenopausal women in the referent group.<br />

Nonlinearities in cumulative PbB index and<br />

tibia and calcaneus Pb suggest differences in<br />

Pb transfer from whole blood to bone among<br />

smelter employees. Contribution to PbB from<br />

bone stores at any instant in time is similar <strong>for</strong><br />

all occupationally exposed populations, active<br />

or retired.<br />

Age-related variations in bone turnover are<br />

not a dominant factor in endogenous exposure<br />

<strong>of</strong> male lead workers. More rapid absorption<br />

<strong>of</strong> Pb in calcaneus than tibia.


AX4-13<br />

Table AX4-5 (cont’d). Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

Canada (cont’d)<br />

Fleming et al. (1998)<br />

Canada<br />

1994<br />

Brito et al. (2000)<br />

Canada<br />

1993-98<br />

Primary smelter.<br />

ALAD 1-1 (n = 303) and ALAD1-2, 2-2<br />

(n = 65).<br />

PbB, serum Pb, cumulative PbB index,<br />

ALAD genotype, K-shell measures with<br />

109 Cd source.<br />

Aims were to: (i) investigate the long-term<br />

human Pb metabolism by measuring the<br />

change <strong>of</strong> Pb concentration in the tibia and<br />

calcaneus between 1993 and 1998; and (ii)<br />

assess whether improved industrial hygiene<br />

was resulting in a slow accumulation <strong>of</strong> Pb<br />

in an exposed work<strong>for</strong>ce. 101 workers in a<br />

secondary lead smelter, 51 subjects had<br />

similar bone Pb measurements in 1993.<br />

Most other subjects had been hired since<br />

1993. Cumulative PbB index. Linear<br />

regressions.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

1-1: PbB 22.9, tibia 41.2, calcaneus 71.6<br />

1-2, 2-2: PbB 25.2, tibia 42.7, calcaneus 72.3.<br />

Slopes <strong>of</strong> linear relations <strong>of</strong> bone Pb to cumulative<br />

PbB index were greater <strong>for</strong> workers homoallelic <strong>for</strong><br />

ALAD 1, indicating more efficient uptake <strong>of</strong> lead<br />

from blood into bone; effect most significant in<br />

calcaneus bone and <strong>for</strong> workers hired since improved<br />

safety measures enacted in 1977 [ALAD1-1: 0.0528<br />

± 0.0028 and ALAD1-2 or 2-2: 0.0355 ± 0.0031<br />

(p < 0.001)].<br />

Repeats (n = 51)<br />

1993: Tibia 39 (±19), calcaneus 64 (±36).<br />

1998: Tibia 33 (±18), calcaneus 65 (±38).<br />

Non-repeats (n = 50)<br />

1998: Tibia 15 (±16), calcaneus 13 (±18).<br />

Tibia Pb decreased significantly (p < 0.001) in the<br />

51 subjects with repeated bone Pb measurements.<br />

Tibia Pb in 1993 and changes in cumulative PbB index<br />

were significant predictors <strong>of</strong> changes in tibia Pb.<br />

An overall half-life <strong>of</strong> 15 yr (95% CI: 9, 55 yr) was<br />

estimated. Adding continuing lead exposure and<br />

recirculation <strong>of</strong> bone lead stores to the regression<br />

models produced half-life estimates <strong>of</strong> 12 and 9 yr,<br />

respectively, <strong>for</strong> release <strong>of</strong> lead from the tibia. Repeat<br />

subjects showed no net change in calcaneus Pb after<br />

5 yr.<br />

Decreased transfer <strong>of</strong> PbB into bone in<br />

individuals expressing the ALAD2 allele<br />

contrasted with increased PbB. ALAD<br />

genotype affected lead metabolism and<br />

potentially modified lead delivery to target<br />

organs including the brain but ALAD<br />

genotype did not significantly affect the net<br />

accumulation <strong>of</strong> lead in bone.<br />

The decrease in new exposure coupled to<br />

release <strong>of</strong> previously stored bone Pb resulted<br />

in a significant decrease in tibia Pb in the<br />

repeat subjects. The rate <strong>of</strong> clearance <strong>of</strong> Pb<br />

from the tibia <strong>of</strong> 9 to 15 yr is towards the<br />

more rapid end <strong>of</strong> previous estimates. The<br />

lack <strong>of</strong> a significant change in the calcaneus<br />

Pb was surprising and if confirmed would<br />

have implications <strong>for</strong> models <strong>of</strong> Pb<br />

metabolism.


AX4-14<br />

Table AX4-5 (cont’d). Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

Canada (cont’d)<br />

Brito et al. (2002)<br />

Canada<br />

1994, 1999<br />

Europe<br />

Somervaille et al. (1988)<br />

England<br />

Christ<strong>of</strong>fersson et al.<br />

(1984)<br />

Sweden<br />

Unknown<br />

Christ<strong>of</strong>fersson et al.<br />

(1986)<br />

Sweden<br />

1978-84<br />

Evaluated endogenous release <strong>of</strong> Pb from<br />

bone to blood in 204 exposed subjects<br />

resuming their duties after a 10-mo strike<br />

in a primary lead smelter in 1991. Bone<br />

Pb ( 109 Cd source) measured in the tibia and<br />

calcaneus in 1994 (Fleming et al., 1997)<br />

and 1999. A linear model used to predict<br />

the current PbB upon the level <strong>of</strong> lead in<br />

bone. 327 subjects available on both<br />

occasions. Group H higher PbB and<br />

Group L lower PbB.<br />

K-shell measures with 109 Cd source on<br />

diverse Pb workers and controls<br />

Crystal glass (n = 87); Battery plant<br />

(n = 88); Precious metals (n = 15);<br />

Laboratory (n = 20).<br />

Cumulative PbB index.<br />

<strong>Lead</strong> smelter employees<br />

Active (n = 75); Former plant (n = 32)<br />

Finger bone measurement with 57 Co<br />

source.<br />

Retired lead workers.<br />

Group 1: 7 smelter, 1 storage battery<br />

monitored <strong>for</strong> 2-5 yr directly after end <strong>of</strong><br />

exposure.<br />

Group 2: 6 battery, bone Pb measured 7-<br />

13 yr after end <strong>of</strong> exposure. Finger bone<br />

measurement with 57 Co source from 4 to<br />

9 times.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Group H: PbB 22.0, tibia 19.2 (n = 120)<br />

Group L: PbB 20.6, tibia 82.8 (n = 45)<br />

Group H: PbB 24.2, calcaneus 41.4 (n = 90)<br />

Group L: PbB 20.2,calcaneus 138.2 (n = 45)<br />

Structural analysis <strong>of</strong> data gave slopes <strong>for</strong> tibia<br />

(2.0, 95% CI: 1.66-2.54) and calcaneus (0.19, 95%<br />

CI: 0.16-0.23) that were significantly higher than<br />

those predicted by the commonly used simple linear<br />

regression method, <strong>for</strong> tibia (0.73, 95%, CI:<br />

0.58-0.88) and calcaneus (0.08, 95% CI: 0.06-0.09).<br />

Crystal glass: PbB 48.1, tibia 31.0<br />

Battery plant: PbB 32.3, tibia 32.3<br />

Precious metals: PbB 51.4, tibia 54.8<br />

Laboratory: PbB 13.1, tibia 16.7<br />

Active: median PbB 53.8 (15.5), mean tibia 43<br />

(


AX4-15<br />

Table AX4-5 (cont’d). Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

Europe (cont’d)<br />

Hanninen et al. (1998)<br />

Finland<br />

Unknown<br />

Erkkilä et al. (1992)<br />

Finland<br />

Unknown<br />

Nilsson et al. (1991)<br />

Sweden<br />

1980s<br />

Storage battery workers<br />

Grouped into those whose PbB exceeded<br />

50 µg/dL [High PbB (n = 28; 21 males)],<br />

and never [Low PbB (n = 26; 22 males)].<br />

Evaluation <strong>of</strong> neuropsychological<br />

dysfunction.<br />

K-shell measures with 109 Cd source on acid<br />

battery employees and controls<br />

Active (n = 91); Former plant (n = 16);<br />

Office (n = 38); Laboratory (n = 26). Kshell<br />

XRF.<br />

Group A: 7 retired smelter workers and<br />

1 battery worker monitored <strong>for</strong> ~10 yr with<br />

11-17 finger bone measurements with<br />

57 Co.<br />

Group B: 6 retired battery workers<br />

monitored <strong>for</strong> up to 18.5 yr with 7-13<br />

finger bone measurements.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

High PbB: average PbB 39.3 (±8.3), tibia 35.3<br />

(±16.6), calcaneus 100.4 (±43.1)<br />

Low PbB: average PbB 29.0 (±6.2), tibia 19.8<br />

(±13.7), calcaneus 78.6(±62.4)<br />

Active: PbB 30.0 (9.5), tibia 21.1 (17), calcaneus 76.6<br />

(55.3)<br />

Former plant: PbB 12.2 (6.2), tibia 32.4 (34.9),<br />

calcaneus 73.5 (57.7)<br />

Office: PbB 6.4 (3.3), tibia 7.7 (11.3), calcaneus 14.2<br />

(15.6)<br />

Laboratory: PbB 3.7 (1.7), tibia 3.5 (10.8), calcaneus<br />

1.2 (10.6)<br />

Bone Pb values decreased over time.<br />

A mono-exponential retention model was used.<br />

Group A: estimated half-life <strong>for</strong> bone Pb was<br />

6.2-27 yr.<br />

Group B: half-life was 11-470 yr.<br />

No relation was found between the<br />

neuropsychological test battery and tibial<br />

Pb.<br />

Tibia Pb concentration increased<br />

consistently both as a function <strong>of</strong> intensity<br />

<strong>of</strong> exposure and duration <strong>of</strong> exposure.<br />

Calcaneal Pb concentration strongly<br />

dependent on the intensity rather than<br />

duration <strong>of</strong> exposure. Biological half-life<br />

<strong>of</strong> Pb in calcaneus


AX4-16<br />

Table AX4-5 (cont’d). Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

Europe (cont’d)<br />

Gerhardsson et al.<br />

(1993)<br />

Sweden<br />

Unknown<br />

Börjesson et al. (1997)<br />

Sweden<br />

1992<br />

Bergdahl et al. (1998)<br />

Sweden<br />

1986<br />

Erfurth et al. (2001)<br />

Sweden<br />

Pb smelter and truck assembly (referent)<br />

workers; Active smelter (n = 70); Retired<br />

smelter (n = 30); Truck assembly (n = 31);<br />

Retired truck assembly (n = 10). K-shell<br />

measures with 109 Cd source.<br />

Pb smelter and referent male metal<br />

workers Active smelter (n = 71); Retired<br />

smelter (n = 18); Referent active (n = 27);<br />

Referent retired (n = 8). Similar cohort to<br />

Gerhardsson et al. (1993). Finger bone<br />

measurement with 57 Co source.<br />

Cumulative PbB index.<br />

Secondary Pb smelter<br />

Exposed (n = 77); Referents (n = 24). Kshell<br />

measures with 109 Cd source.<br />

Cumulative PbB index and (calculated)<br />

plasma Pb.<br />

Secondary smelter<br />

Active (n = 62); Retired (n = 15);<br />

Referents (n = 26).<br />

Evaluation <strong>of</strong> effects <strong>of</strong> Pb on the<br />

endocrine system.<br />

Finger bone measures with 57 Co source.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Median values presented.<br />

Active smelter: PbB 31.9 (5.0, 47.4), tibia 13.0<br />

(!4.1, 72.8), calcaneus 48.6 (0.4, 217.8)<br />

Retired smelter: PbB 9.9 (3.3, 21), tibia 39.3<br />

(2.9, 73.4), calcaneus 100.2 (34.8, 188.9)<br />

Truck: PbB 4.1 (1.7, 12.4), tibia 3.4<br />

(!9.4, 13.3), calcaneus 12.2 (!12.7, 43.0)<br />

Retired truck: PbB 3.5 (2.2, 12.2), tibia 12.0<br />

(!6.7, 23.7), calcaneus 30.2 (!7.1, 56.7)<br />

Median values presented.<br />

Active smelter: PbB 33.1 (8.3, 93),<br />

bone Pb 23.0 (!13, 99)<br />

Retired smelter: PbB 17.2 (8.9, 33.1),<br />

bone Pb 55 (3, 88)<br />

Active referent: PbB 3.7 (0.8, 7.0),<br />

bone Pb 3 (!21, 16)<br />

Retired referent: PbB 3.9 (3.1, 6.2),<br />

bone Pb 1.5 (!3, 12)<br />

Exposed: PbB 35.0 (14, 57), tibia 25 (5, 193),<br />

calcaneus 52 (!20, 458)<br />

Referents: PbB 5.0 (2.9, 16). tibia 10 (!6, 36),<br />

calcaneus 11(!12, 61)<br />

Median values presented.<br />

Active: PbB 33.2 (8.3, 93.2), tibia 21 (!13, 99)<br />

Retired: PbB 18.6 (10.4, 49.7), tibia 55 (3, 88)<br />

Referents: PbB 4.1 (0.8, 6.2), tibia 2 (!21, 14)<br />

Higher calcaneus Pb than tibia Pb in active<br />

lead workers suggested more rapid<br />

absorption over time in this mainly<br />

trabecular bone. Estimated biological half<br />

times were 16 yr in calcaneus (95% CI:<br />

11, 29 yr) and 27 yr in tibia (95% CI: 16,<br />

98 yr). Strong positive correlation between<br />

bone Pb and cumulative PbB index.<br />

Multiple regression analyses showed bone<br />

Pb was best described by the cumulative<br />

PbB index, which explained 29% <strong>of</strong> the<br />

observed variance (multiple r 2 ) in bone Pb<br />

in active workers and about 39% in retired<br />

workers. Estimated biological half-life <strong>of</strong><br />

bone Pb among active lead workers was<br />

5.2 yr (95% CI: 3.3-13.0 yr).<br />

Strong relationships between the tibia Pb<br />

(r 2 = 0.78) and calcaneus (r 2 = 0.80) and<br />

cumulative PbB index. Half-lives <strong>of</strong> Pb in<br />

tibia 13-24 yr and calcaneus 12-19.<br />

No significant associations between bone<br />

Pb and pituitary and thyroid hormones,<br />

serum testosterone, gonadotropin-releasing<br />

hormone and thyroid releasing hormone.


AX4-17<br />

Table AX4-5 (cont’d). Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Reference, Study<br />

Location, and Period Study Description<br />

Europe (cont’d)<br />

Roels et al. (1995)<br />

Belgium<br />

Mexico<br />

Juarez-Perez et al.<br />

(2004)<br />

Mexico City<br />

1996-7<br />

Asia<br />

Schwartz et al. (2001)<br />

Korea<br />

1997-99<br />

Pb smelter and others.<br />

Active production (n = 73); Other<br />

departments (n = 50). K-shell measures<br />

with 109 Cd source. Cumulative PbB index.<br />

Lithographic print shop workers; Males,<br />

n = 59, 10 females; mean age 47 yrs<br />

Plasma Pb by ultraclean ICP-MS methods.<br />

K-shell measures with 109 Cd source.<br />

Korean Pb workers (798, 639 male,<br />

164 female) and controls (135, 124 male,<br />

1 female). Evaluation <strong>of</strong> associations<br />

between PbB, tibia Pb, chelatable Pb, and<br />

neurobehavioral functions. K-shell<br />

measures with 109 Cd source.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Active: PbB 42.0, tibia 66.5<br />

Others: PbB 14.5, tibia 31.4<br />

PbB 11.9 (±5.8), tibia 27.6 (±18.1; ND-73.8),<br />

patella 46.8 (±29.3; ND-139)<br />

Active: PbB 32 (±15), tibia 37.2 (±40.4)<br />

Controls: PbB 5.3 (±1.8), tibia 5.8 (±7.0).<br />

Strong relationship between bone Pb and<br />

cumulative PbB index in smelter<br />

populations (r = 0.80, p < 0.0001; age<br />

explained #9.5% <strong>of</strong> variance). Slope <strong>of</strong><br />

regression equation <strong>of</strong> log bone Pb versus<br />

log cumulative PbB index showed that<br />

doubling <strong>of</strong> cumulative PbB index<br />

corresponds to doubling <strong>of</strong> bone Pb.<br />

Statistically significant associations<br />

between: plasma Pb and PbB, patella Pb,<br />

tibia Pb, age, education, use <strong>of</strong> Pb-glazed<br />

ceramics but not air Pb, hand Pb or hygiene<br />

index at work. Multiple linear regression<br />

models with patella and tibia Pb as main<br />

predictors and adjusting <strong>for</strong> PbB and<br />

hygiene index explained 57% <strong>of</strong> variability<br />

in plasma Pb. Negative association<br />

between plasma Pb and hygiene index<br />

suggest oral exposure and gastrointestinal<br />

uptake <strong>of</strong> Pb predominant source <strong>of</strong> Pb<br />

exposure in these subjects.<br />

After adjustment <strong>for</strong> covariates, tibia Pb<br />

was not associated with neurobehavioral<br />

test scores.


AX4-18<br />

Reference, Study<br />

Location, and Period Study Description<br />

Asia (cont’d)<br />

Todd et al. (2001)<br />

Korea<br />

PbB = blood lead.<br />

Table AX4-5 (cont’d). Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects<br />

Korean Pb workers active (n = 723),<br />

retired (n = 79), controls (n = 135).<br />

Evaluation <strong>of</strong> associations between PbB,<br />

tibia Pb, chelatable Pb.<br />

K-shell measures with 109 Cd source.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Active: median PbB 31.7, tibia 24.4<br />

(−7.4, 337.6)<br />

Retired: median PbB 13.5, tibia 26.4<br />

(−6.7, 196.7)<br />

Controls: median PbB 5.1, tibia 5.0<br />

(−10.9, 26.6)<br />

Control women higher bone Pb than men.<br />

Job duration, body mass index, and age<br />

were positive predictors <strong>of</strong> tibial Pb. Rate<br />

<strong>of</strong> increase in tibia Pb with age itself<br />

increased with increasing age. Tibial Pb<br />

stores in older subjects are less bioavailable<br />

and may contribute less to PbB than tibial<br />

stores in younger subjects.


AX4-19<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States<br />

Korrick et al.<br />

(2002)<br />

Boston, MA<br />

1990-95<br />

Popovic et al.<br />

(2005)<br />

Bunker Hill, ID<br />

1994<br />

Nurses’ Health Study. Crosssectional<br />

study <strong>of</strong> 264 elderly<br />

women; 46-54 yr (n = 80) 55-64<br />

yr (n = 102), 65-74 yr (n = 82).<br />

Tibia and patella Pb. Multivariate<br />

linear regression models.<br />

108 <strong>for</strong>mer female smelter<br />

employees and 99 referents to<br />

assess the PbB versus bone Pb<br />

relationship<br />

Table AX4-6. Bone <strong>Lead</strong> Contribution to PbB<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

46-54 yr: PbB 2.7 (SE ±0.3), tibia 10.5 (±1.0), patella<br />

14.9 (±1.2)<br />

55-64 yr: PbB 3.4 (±0.2), tibia 12.7 (±0.9), patella 17.0 (±1.1)<br />

65-74 yr: PbB 3.3 (±0.3), tibia 16.4 (±0.9), patella 19.8 (±1.2).<br />

An increase from the first to the fifth quintile <strong>of</strong> tibia Pb level<br />

(19 µg/g) was associated with a 1.7 µg/dL increase in PbB<br />

(p 0.0001).<br />

Exposed: PbB 2.73 (±2.39), tibia 14.4 (±0.5)<br />

Referents: PbB 1.25 (±2.10), tibia 3.22 (±0.50)<br />

Pb concentrations in tibia and blood significantly higher in the<br />

exposed group. Endogenous release rate (µg Pb per dL blood/µ<br />

Pb/g bone) in postmenopausal women was double the rate found<br />

in premenopausal women (0.132 ± 0.019 vs. 0.067 ± 0.014).<br />

Tibia and patella Pb values were significantly<br />

and positively associated with PbB but only<br />

among postmenopausal women who were not<br />

using estrogens. Older age and lower parity<br />

were associated with higher tibia Pb; only age<br />

was associated with patella Pb. They<br />

suggested the observed interaction <strong>of</strong> bone Pb<br />

with estrogen status in determining PbB<br />

supports the hypothesis that increased bone<br />

resorption, as occurs postmenopausally<br />

because <strong>of</strong> decreased estrogen production,<br />

results in heightened release <strong>of</strong> bone Pb stores<br />

into blood.<br />

Higher tibia bone Pb (and PbB) was associated<br />

with use <strong>of</strong> estrogen (present or <strong>for</strong>mer) in<br />

both the whole referent group and<br />

postmenopausal women in the referent group.


AX4-20<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Canada<br />

Brito et al. (2000)<br />

Canada<br />

1993-98<br />

Brito et al. (2002)<br />

Canada<br />

1994, 1999<br />

Aims were to: (i) investigate the<br />

long term human Pb metabolism by<br />

measuring the change <strong>of</strong> Pb<br />

concentration in the tibia and<br />

calcaneus between 1993 and 1998;<br />

and (ii) assess whether improved<br />

industrial hygiene was resulting in a<br />

slow accumulation <strong>of</strong> Pb in an<br />

exposed work<strong>for</strong>ce. 101 workers in a<br />

secondary lead smelter, 51 subjects<br />

had similar bone Pb measurements in<br />

1993. Most other subjects had been<br />

hired since 1993. Cumulative PbB<br />

index. Linear regressions.<br />

Evaluated endogenous release <strong>of</strong> Pb<br />

from bone to blood in 204 exposed<br />

subjects resuming their duties after a<br />

10-mo strike in a primary lead<br />

smelter in 1991. Bone Pb ( 109 Cd<br />

source) measured in the tibia and<br />

calcaneus in 1994 (Fleming et al.,<br />

1997) and 1999. A linear model<br />

used to predict the current PbB upon<br />

the level <strong>of</strong> lead in bone.<br />

327 subjects available on both<br />

occasions. Group H higher PbB and<br />

Group L lower PbB.<br />

Table AX4-6 (cont’d). Bone <strong>Lead</strong> Contribution to PbB<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Repeats (n = 51)<br />

1993: Tibia 39 (±19), calcaneus 64 (±36).<br />

1998: Tibia 33 (±18), calcaneus 65 (±38).<br />

Non-repeats (n = 50)<br />

1998: Tibia 15 (±16), calcaneus 13 (±18).<br />

Tibia Pb decreased significantly (p


AX4-21<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico<br />

Brown et al.<br />

(2000)<br />

Mexico City<br />

1994-5<br />

Téllez-Rojo et al.<br />

(2002)<br />

Mexico City<br />

1994-95<br />

Garrido-Latorre<br />

et al. (2003)<br />

Mexico City<br />

1995<br />

PbB = blood lead.<br />

Investigated determinants <strong>of</strong> bone Pb<br />

and PbB <strong>of</strong> 430 lactating Mexican<br />

women during the early postpartum<br />

period and contribution <strong>of</strong> bone Pb to<br />

PbB. Linear regression analyses.<br />

Evaluated the hypothesis that<br />

lactation stimulates Pb release from<br />

bone to blood. Cross–sectional<br />

examination <strong>of</strong> breastfeeding patterns<br />

and bone Pb as determinants <strong>of</strong> PbB<br />

among 425 lactating women (mean<br />

age 24.8 ± 5.3 yr) <strong>for</strong> 7 mo after<br />

delivery. Bone Pb at 1 mo<br />

postpartum. Maternal blood samples<br />

and questionnaire in<strong>for</strong>mation<br />

collected at delivery and at 1, 4, and<br />

7 mo postpartum. Generalized<br />

estimating equations.<br />

Aim was to examine the relationship<br />

<strong>of</strong> PbB levels to menopause and bone<br />

lead levels in 232 perimenopausal<br />

and postmenopausal women from<br />

Mexico City. Measured bone<br />

mineral density in addition to bone<br />

Pb. In<strong>for</strong>mation regarding<br />

reproductive characteristics and<br />

known risk factors <strong>for</strong> PbB was<br />

obtained using a standard<br />

questionnaire by direct interview.<br />

Mean age <strong>of</strong> the population was<br />

54.7 yrs (±9.8). Linear regression<br />

analyses.<br />

Table AX4-6 (cont’d). Bone <strong>Lead</strong> Contribution to PbB<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

PbB 9.5 (±4.5), tibia 10.2 (±10.1), patella 15.2 (±15.1). Older age, use <strong>of</strong> Pb glazed pottery, and higher<br />

proportion <strong>of</strong> life spent in Mexico City were<br />

main predictors <strong>of</strong> higher tibia and patella Pb.<br />

Women in the 90th percentile <strong>for</strong> patella Pb<br />

had an untrans<strong>for</strong>med predicted mean PbB 3.6<br />

µg/dL higher than those in the 10th percentile.<br />

Mean PbB decreased with time postpartum: 1 mo 9.4 (±4.4),<br />

4 mo 8.9 (±4.0), 7 mo 7.9 (±3.3).<br />

Tibia 10.6 (11.6 after correction <strong>for</strong> negative values), patella<br />

15.3 (16.9 after correction). After adjustment <strong>for</strong> bone Pb and<br />

environmental exposure, women who exclusively breastfed<br />

their infants had PbB levels that were increased by 1.4 µg/dL<br />

and women who practiced mixed feeding had levels increased<br />

by 1.0 µg/dL, in relation to those who had stopped lactation.<br />

A 10 µg Pb/g increment in patella and tibia bone Pb increased<br />

PbB by 6.1% (95% CI: 4.2, 8.1) and 8.1% (95% CI: 5.2,<br />

11.1), respectively.<br />

PbB 9.2 (±4.7), tibia 14.85 (±10.1), patella 22.73 (±14.9).<br />

A change <strong>of</strong> 10 µg Pb/g bone mineral in postmenopausal<br />

subjects was associated with an increase in PbB <strong>of</strong> 1.4 µg/dL,<br />

whereas a similar change in bone lead among premenopausal<br />

women was associated with an increase in PbB <strong>of</strong> 0.8 µg/dL.<br />

They concluded that their results support the<br />

hypothesis that lactation is directly related to<br />

the amount <strong>of</strong> Pb released from bone.<br />

Found that postmenopausal women using<br />

hormone replacement therapy had lower PbB<br />

levels and higher tibia and patella bone Pb<br />

levels than non-users; patella Pb explained the<br />

greatest part <strong>of</strong> variations in PbB. Found no<br />

association with PbB levels and did not<br />

describe any relationships between bone lead<br />

and bone density.


AX4-22<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States<br />

Hu et al. (1996)<br />

Boston, MA<br />

1990<br />

Rothenberg et al<br />

(2000)<br />

Los Angeles, CA<br />

1995-98<br />

Rothenberg et al.<br />

(2002)<br />

Los Angeles, CA<br />

1995-2001<br />

Table AX4-7. Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Cord PbB measured in 223<br />

women, 41 bone Pb measured<br />

at 1-4 postpartum. ANOVA.<br />

Examined bone Pb contribution to<br />

PbB in a group <strong>of</strong> 311 immigrant<br />

women (mean age 27.8 ±7.5 yr),<br />

99% from Latin America, during<br />

the 3rd trimester <strong>of</strong> pregnancy, and<br />

1 to 2 mo after delivery. Multiple<br />

regression, variance-weighted<br />

least squares regression, structural<br />

equation modeling.<br />

Examined the effects <strong>of</strong> blood and<br />

bone PbB on hypertension and<br />

elevated blood pressure in the 3rd<br />

trimester and postpartum among<br />

1,006 mostly Latina and Afro-<br />

American women. Multiple and<br />

logistic regression.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Values omitted if measurement uncertainty was >10 µg/g <strong>for</strong> tibia and<br />

15 µg/g <strong>for</strong> patella.<br />

Cord PbB 1.19 (±1.32), maternal PbB 2.9 (±2.6), tibia 4.5 (±4.0) patella 5.8<br />

(±4.5).<br />

Maternal age was the only factor marginally associated with combined bone<br />

Pb (p = 0.08) but not individually with tibia or patella Pb.<br />

Prenatal PbB 2.2 (+4.8/!1.0, geometric mean), postnatal PbB 2.8<br />

(+4.9/!1.2) (p < 0.0001), tibia 6.7(±12.5), calcaneus 8.4 (±13.2). Varianceweighted<br />

multiple regression and structural equation models showed that<br />

both calcaneus and tibia Pb were directly associated with prenatal PbB but<br />

only calcaneus Pb was associated with postnatal PbB. Increasing natural log<br />

yrs in the United States independently predicted decreasing calcaneus and<br />

3rd trimester PbB.<br />

Returned and eligible: 3rd trimester PbB (n = 720) 1.9 (+3.6/!1.0),<br />

postpartum PbB (n = 704) 2.3 (+4.3/!1.2), tibia (n = 700) 8.0 (±11.4),<br />

calcaneus (n = 700) 10.7 (±11.9). Returned but ineligible: 3rd trimester<br />

PbB (n = 279) 1.9 (+4.2/!0.8), postpartum PbB (n = 274) 2.3 (+4.7/!1.1),<br />

tibia (n = 263) 8.7 (±13.9), calcaneus (n = 262) 11.2 (±15.1). For each<br />

10 µg/g increase in calcaneus Pb level, the odds ratio <strong>for</strong> 3rd trimester<br />

hypertension (systolic blood pressure $140 mmHg or diastolic blood<br />

pressure $90 mmHg) was 1.86 (95% CI: 1.04, 3.32). In normotensive<br />

subjects, each 10 µg/g increase in calcaneus Pb level was associated with a<br />

0.70 mmHg (95% CI: 0.04, 1.36) increase in 3rd trimester systolic blood<br />

pressure and a 0.54 mmHg (95% CI: 0.01, 1.08) increase in diastolic blood<br />

pressure after adjusting <strong>for</strong> postpartum hypertension, education,<br />

immigration status, current smoking, current alcohol use, parity, age, and<br />

body mass index. Tibia bone Pb was not related to hypertension or elevated<br />

blood pressure either in the 3rd trimester or postpartum, nor was calcaneus<br />

Pb related to postpartum hypertension or elevated blood pressure.<br />

Umbilical cord PbB among<br />

women served by this Boston<br />

hospital declined dramatically<br />

from 1980 to 1990.<br />

Suggest that while some<br />

exogenous Pb sources and<br />

modulators <strong>of</strong> PbB, such as use<br />

<strong>of</strong> Pb-glazed pottery and calcium<br />

in the diet, control Pb exposure<br />

during and after pregnancy,<br />

endogenous Pb sources from past<br />

exposure be<strong>for</strong>e immigration<br />

continue to influence PbB levels<br />

in this cohort.<br />

The authors concluded that past<br />

Pb exposure influences<br />

hypertension and elevated blood<br />

pressure during pregnancy and<br />

controlling blood pressure may<br />

require reduction <strong>of</strong> Pb exposure<br />

long be<strong>for</strong>e pregnancy.


AX4-23<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico<br />

Hernandez-Avila<br />

et al. (1996)<br />

Mexico City<br />

González-Cossío<br />

et al. (1997)<br />

Mexico City<br />

Unknown<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Cross-sectional investigation <strong>of</strong><br />

the interrelationships between<br />

environmental, dietary, and<br />

lifestyle histories, blood and bone<br />

Pb levels, among 98 recently<br />

postpartum women. Multivariate<br />

linear regression. Age 25.6<br />

(±6.8) yr.<br />

Examined relationship <strong>of</strong> Pb levels<br />

in cord blood and maternal bone to<br />

birth weight. Umbilical cord and<br />

maternal venous blood samples<br />

and anthropometric and<br />

sociodemographic data were<br />

obtained at delivery and 1 mo<br />

postpartum. Bone Pb at 1 mo<br />

postpartum. Multiple regression,<br />

LOWESS.<br />

Background in<strong>for</strong>mation <strong>for</strong><br />

calcium supplementation study<br />

Hernandez-Avila et al. (2003).<br />

Mother-infant pairs (n = 272).<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

14-20 yr (n = 24): PbB 10.4 (±4.1), tibia 11.8 (±14.9), patella 14.1 (±13.3).<br />

21-29 yr (n = 44): PbB 10.3 (±4.8), tibia 10.7 (± 10.9), patella 17.1 (±13.4)<br />

30-43 yr (n = 27): PbB 7.8 (± 3.7), tibia 16.3 (±8.4), patella 18.1 (±12.7).<br />

A 34 µg/g increase in patella Pb (from the medians <strong>of</strong> the lowest to the<br />

highest quartiles) was associated with an increase in PbB <strong>of</strong> 2.4 µg/dL.<br />

Significant predictors <strong>of</strong> bone Pb included years living in Mexico City,<br />

lower consumption <strong>of</strong> high calcium content foods, and nonuse <strong>of</strong> calcium<br />

supplements <strong>for</strong> the patella and years living in Mexico City, older age, and<br />

lower calcium intake <strong>for</strong> tibia bone. Low consumption <strong>of</strong> milk and cheese,<br />

as compared to the highest consumption category (every day), was<br />

associated with an increase in tibia Pb <strong>of</strong> 9.7 µg/g.<br />

Maternal PbB 8.9 (±4.1), cord PbB 7.1 (±3.5), tibia 9.8 (±8.9), patella 14.2<br />

(±13.2).<br />

After adjustment <strong>for</strong> other determinants <strong>of</strong> birth weight, tibia Pb was the<br />

only Pb biomarker clearly related to birth weight. The decline in birth<br />

weight associated with increments in tibia Pb was nonlinear and accelerated<br />

at the highest tibia Pb quartile. In the upper quartile, neonates were on<br />

average, 156 g lighter than those in the lowest quartile.<br />

Suggest that patella bone is a<br />

significant contributor to PbB<br />

during lactation and that<br />

consumption <strong>of</strong> high calcium<br />

content foods may protect<br />

against the accumulation <strong>of</strong> Pb<br />

in one.<br />

Bone-lead burden is inversely<br />

related to birth weight.


AX4-24<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico (cont’d)<br />

Brown et al. (2000)<br />

Mexico City<br />

1994-5<br />

Chuang et al. (2001)<br />

Mexico City<br />

1994-95<br />

Ettinger et al. (2004)<br />

Mexico City<br />

1994-95<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Investigated determinants <strong>of</strong> bone<br />

Pb and PbB <strong>of</strong> 430 lactating<br />

Mexican women during the early<br />

postpartum period and<br />

contribution <strong>of</strong> bone Pb to PbB.<br />

Linear regression analyses.<br />

Aim to estimate the contribution<br />

<strong>of</strong> maternal whole PbB and bone<br />

Pb, and environmental Pb to<br />

umbilical cord PbB (as a measure<br />

<strong>of</strong> fetal Pb exposure). Maternal<br />

and umbilical cord blood samples<br />

within 12 hr <strong>of</strong> each infant's<br />

delivery. Structural equation<br />

modeling.<br />

Aim to quantify the relation<br />

between maternal blood and bone<br />

Pb and breast-feeding status<br />

among 310 lactating women in<br />

Mexico City, Mexico, at 1 mo<br />

postpartum. Breast milk<br />

measured. Multiple linear<br />

regression, LOWESS smoothing.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

PbB 9.5 (±4.5), tibia 10.2 (±10.1), patella 15.2 (±15.1). Older age, use <strong>of</strong> Pb glazed<br />

pottery, and higher proportion <strong>of</strong><br />

life spent in Mexico City were<br />

main predictors <strong>of</strong> higher tibia<br />

and patella Pb. Women in the<br />

90th percentile <strong>for</strong> patella Pb had<br />

an untrans<strong>for</strong>med predicted<br />

mean PbB 3.6 µg/dL higher than<br />

those in the 10th percentile.<br />

Bone Pb measured within 1 mo after delivery. PbB 8.45 (±3.94, n = 608),<br />

tibia 9.67 (±9.21, n = 603), patella 14.24 (±14.19, n = 575).<br />

Tibia and patella Pb, use <strong>of</strong> Pb glazed ceramics, and mean air Pb level<br />

contributed significantly to plasma Pb. An increase in patella Pb and tibia<br />

Pb was associated with increases in cord PbB <strong>of</strong> 0.65 and 0.25 µg/dL,<br />

respectively.<br />

Breastfeeding: PbB 9.3 (±4.4, n = 310), tibia 9.6 (±10.1, n = 303), patella<br />

14.5 (±14.9, n = 294).<br />

Non breastfeeding: PbB 9.3 (±4.9, n = 319), tibia 10.5 (±10.2, n = 306),<br />

patella 15.2 (±16.1, n = 289). Breast milk geometric mean 1.1 (range<br />

0.21-8.02) µg/L. Breast milk Pb significantly correlated with umbilical cord<br />

Pb and maternal PbB at delivery and with maternal PbB and patella Pb at<br />

1 mo postpartum. An interquartile range increase in patella Pb (20 µg/g)<br />

was associated with a 14% increase in breast milk lead (95% CI: 5, 25%).<br />

An IQR increase in tibia Pb (12.0 µg/g) was associated with a 5% increase<br />

in breast milk lead (95% CI: !3, 14).<br />

Suggested that maternal plasma<br />

Pb varies independently from<br />

maternal whole PbB.<br />

Contributions from endogenous<br />

(bone) and exogenous<br />

(environmental) sources were<br />

approximately the same.<br />

(Plasma Pb not measured).<br />

Suggest that even among a<br />

population <strong>of</strong> women with<br />

relatively high lifetime Pb<br />

exposure, breast milk Pb levels<br />

are low, influenced both by<br />

current Pb exposure and by<br />

redistribution <strong>of</strong> bone Pb<br />

accumulated from past<br />

environmental exposures.


AX4-25<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico (cont’d)<br />

Sanín et al. (2001)<br />

Mexico City<br />

1994-95<br />

Gomaa et al. (2002)<br />

Mexico City<br />

Unknown<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Examined early postnatal growth<br />

in a cohort <strong>of</strong> healthy breastfed<br />

newborns in relation to maternal<br />

bone Pb burden. 329 motherinfant<br />

pairs sampled <strong>for</strong> umbilical<br />

cord blood at birth and maternal<br />

and infant venous blood at 1 mo<br />

postpartum. Maternal evaluations<br />

at 1 mo postpartum included Pb<br />

measures in blood and bone.<br />

Primary endpoints were attained<br />

weight 1 mo <strong>of</strong> age, and weight<br />

gain from birth to 1 mo <strong>of</strong> age.<br />

Linear regression.<br />

Aim to compare umbilical cord<br />

PbB and maternal bone Pb as<br />

independent predictors <strong>of</strong> infant<br />

mental development (n = 197).<br />

Prospective design. At 24 mo <strong>of</strong><br />

age, each infant was assessed<br />

using the Bayley Scales <strong>of</strong> Infant<br />

Development-<strong>II</strong> (Spanish<br />

Version). Multiple linear<br />

regression.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Included in analyses (n = 329):<br />

Infant: cord PbB 6.8 (±3.9), PbB 1 mo 5.7 (±3.0)<br />

Maternal: PbB 9.7 (±5.2), tibia Pb 10.1 (±10.3), patella Pb 15.2 (±15.2)<br />

Excluded from analyses (n = 276):<br />

Infant: cord PbB 6.3 (±3.0), PbB 1 mo 5.5 (±3.3)<br />

Maternal: PbB 8.8 (±3.9), tibia Pb 9.75 (±10.3), patella Pb 14.2 (±17.3).<br />

Infant PbB were inversely associated with weight gain, with an estimated<br />

decline <strong>of</strong> 15.1 g/µg/dL <strong>of</strong> PbB. Children who were exclusively breastfed<br />

had significantly higher weight gains; however, this gain decreased<br />

significantly with increasing levels <strong>of</strong> patella Pb. Multivariate regression<br />

analysis predicted a 3.6 g decrease in weight at 1 mo <strong>of</strong> age/µg Pb/g bone<br />

mineral increase in maternal patella Pb levels.<br />

Cord PbB 6.7 (±3.4), tibia 11.5 (±11.0), patella 17.9 (±15.2). After<br />

adjustment <strong>for</strong> confounders, Pb levels in umbilical cord blood and patella<br />

bone were significantly, independently, and inversely associated with the<br />

Mental Development Index (MDI) scores <strong>of</strong> the Bailey Scale. In relation to<br />

the lowest quartile <strong>of</strong> patella Pb, the 2nd, 3rd, and 4th quartiles were<br />

associated with 5.4-, 7.2-, and 6.5-point decrements in adjusted MDI scores.<br />

A 2-fold increase in cord PbB (e.g., from 5-10 µg/dL) was associated with a<br />

3.1-point decrement in MDI score.<br />

The authors concluded that<br />

maternal Pb burden is negatively<br />

associated with infant attained<br />

weight at 1 mo <strong>of</strong> age and to<br />

postnatal weight gain from birth<br />

to 1 mo <strong>of</strong> age.<br />

Suggest that higher maternal<br />

patella bone Pb levels constitute<br />

an independent risk factor <strong>for</strong><br />

impaired mental development in<br />

infants at 24 mo <strong>of</strong> age. This<br />

effect is probably attributable to<br />

mobilization <strong>of</strong> maternal bone Pb<br />

stores.


AX4-26<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico (cont’d)<br />

Hernandez-Avila<br />

et al. (2002)<br />

Mexico City<br />

1994<br />

Téllez-Rojo et al.<br />

(2002)<br />

Mexico City<br />

1994-95<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Aim to evaluate the effects <strong>of</strong><br />

maternal bone Pb stores on<br />

anthropometry at birth in 223<br />

mother-infant pairs.<br />

Anthropometric data were<br />

collected within the first 12 hr<br />

following delivery. Maternal<br />

in<strong>for</strong>mation was obtained 1 mo<br />

after delivery (mean age 24.4 ± 5.4<br />

yr). Trans<strong>for</strong>med anthropometric<br />

measurements to an ordinal 5category<br />

scale, and association <strong>of</strong><br />

measurements with other factors<br />

evaluated with ordinal logisticregression<br />

models. Cumulative<br />

Odds Model.<br />

Evaluated the hypothesis that<br />

lactation stimulates Pb release<br />

from bone to blood.<br />

Cross-sectional examination <strong>of</strong><br />

breastfeeding patterns and bone Pb<br />

as determinants <strong>of</strong> PbB among 425<br />

lactating women (mean age 24.8<br />

±5.3 yr) <strong>for</strong> 7 mo after delivery.<br />

Bone Pb at 1 mo postpartum.<br />

Maternal blood samples and<br />

questionnaire in<strong>for</strong>mation<br />

collected at delivery and at 1, 4,<br />

and 7 mo postpartum. Generalized<br />

estimating equations.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Cord blood 7.01 (±3.5), maternal PbB 8.82 (± 4.0), tibia 10.70 (±7.58,<br />

adjusted <strong>for</strong> negative values), patella 15.39 (±11.18, adjusted <strong>for</strong> negative<br />

values). Maternal PbB increased linearly by 0.096/µg <strong>of</strong> tibia Pb and<br />

0.078/µg patella Pb. Umbilical cord PbB increased by 0.111/µg tibia Pb<br />

and 0.061/µg patella Pb. Birth length <strong>of</strong> newborns decreased as tibia Pb<br />

levels increased (odds ratio <strong>of</strong> 1.03/µg/g bone mineral [95% CI: 1.01,<br />

1.06]).<br />

Mean PbB decreased with time postpartum: 1 mo 9.4 (±4.4), 4 mo 8.9<br />

(±4.0), 7 mo 7.9 (±3.3).<br />

Tibia 10.6 (11.6 after correction <strong>for</strong> negative values), patella 15.3 (16.9 after<br />

correction). After adjustment <strong>for</strong> bone Pb and environmental exposure,<br />

women who exclusively breastfed their infants had PbB levels that were<br />

increased by 1.4 µg/dL and women who practiced mixed feeding had levels<br />

increased by 1.0 µg/dL, in relation to those who had stopped lactation.<br />

A 10 µg Pb/g increment in patella and tibia bone Pb increased PbB by 6.1%<br />

(95% CI: 4.2, 8.1) and 8.1% (95% CI: 5.2, 11.1), respectively.<br />

Compared with women in the<br />

lower quintiles <strong>of</strong> the distribution<br />

<strong>of</strong> tibia Pb, those in the upper<br />

quintile had a 79% increase in<br />

risk <strong>of</strong> having a lower birth<br />

length newborn (OR ratio 1.79;<br />

95% CI: 1.10, 3.22). Patella Pb<br />

was positively related to the risk<br />

<strong>of</strong> a low head circumference<br />

score; this score remained<br />

unaffected by inclusion <strong>of</strong> birth<br />

weight. The increased risk was<br />

1.02/ Fg Pb/g bone mineral (95%<br />

CI: 1.01, 1.04). Odds ratios did<br />

not vary substantially after the<br />

authors adjusted <strong>for</strong> birth weight<br />

and other important determinants<br />

<strong>of</strong> head circumference.<br />

They concluded that their results<br />

support the hypothesis that<br />

lactation is directly related to the<br />

amount <strong>of</strong> Pb released from<br />

bone.


AX4-27<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico (cont’d)<br />

Hernandez-Avila<br />

et al. (2002)<br />

Mexico City<br />

1994<br />

Hernandez-Avila<br />

et al. (2003)<br />

Mexico City<br />

1994-95<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Evaluated the effects that maternal<br />

bone Pb has on anthropometry at<br />

birth in 223 mother-infant pairs.<br />

Anthropometric data (birth length,<br />

head circumference) collected<br />

within the first 12 hr following<br />

delivery. Maternal in<strong>for</strong>mation<br />

was obtained 1 mo postpartum.<br />

Trans<strong>for</strong>med anthropometric<br />

measurements to an ordinal 5category<br />

scale, ordinal logisticregression<br />

models.<br />

Tested the hypothesis that in a<br />

randomized trial <strong>of</strong> lactating<br />

women a dietary calcium<br />

supplement will lower PbB levels.<br />

Lactating women (mean age 24 yr)<br />

were randomly assigned to receive<br />

either calcium carbonate (1200 mg<br />

<strong>of</strong> elemental calcium daily) or<br />

placebo in a double-blind trial.<br />

Blood samples were obtained at<br />

baseline, and 3 and 6 mo after the<br />

trial began. Primary endpoint was<br />

change in maternal PbB in relation<br />

to supplement use and other<br />

covariates with multivariate<br />

generalized linear models <strong>for</strong><br />

longitudinal observations.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Participants (n = 223) Cord blood 7.01 (±3.5), maternal PbB 8.82 (±4.0),<br />

tibia 9.83 (±8.9), patella 14.14 (±13.0).<br />

Nonparticipants (n = 494): Cord blood 6.75 (±3.50), PbB 8.47 (±4.19).<br />

Birth length <strong>of</strong> newborns decreased as tibia Pb levels increased. Compared<br />

with women in the lower quintiles <strong>of</strong> the distribution <strong>of</strong> tibia Pb, those in the<br />

upper quintile had a 79% increase in risk <strong>of</strong> having a lower birth length<br />

newborn (odds ratio 1.79; 95% CI: 1.10, 3.22). The effect was attenuated–<br />

but nonetheless significant- even after adjustment <strong>for</strong> birth weight. Patella<br />

Pb was positively and significantly related to the risk <strong>of</strong> a low head<br />

circumference score; this score remained unaffected by inclusion <strong>of</strong> birth<br />

weight.<br />

Lactating calcium group (n = 296): PbB 9.2 (±4.2), tibia 10.7 (±9.8), patella<br />

16.2 (±15.7)<br />

Lactating placebo (n = 321): PbB 9.4 (± 5.0), tibia 9.6 (±10.3), patella 13.5<br />

(± 15.1)<br />

Women randomized to the calcium supplements experienced a small decline<br />

in PbB <strong>of</strong> 0.29 µg/dL (95% CI: !0.85, !0.26). The effect was more<br />

apparent among women who were compliant with supplement use and had<br />

high patella Pb <strong>of</strong> $5 µg/g. Among this subgroup, supplement use was<br />

associated with an estimated reduction in mean PbB <strong>of</strong> 1.16 µg/dL<br />

(95% CI: !2.08, !0.23), an overall reduction <strong>of</strong> 16.4%.<br />

The authors estimated the<br />

increased risk <strong>of</strong> having a low<br />

head-circumference score to be<br />

1.02/ µg Pb/g bone mineral (95%<br />

CI: 1.01, 1.04). Odds ratios did<br />

not vary substantially after the<br />

authors adjusted <strong>for</strong> birth weight<br />

and other important determinants<br />

<strong>of</strong> head circumference.<br />

Among lactating women with<br />

relatively high Pb burden,<br />

calcium supplementation was<br />

associated with a modest<br />

reduction in PbB levels.


AX4-28<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico (cont’d)<br />

Téllez-Rojo et al.<br />

(2004)<br />

Mexico City<br />

1997-99<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Tested the hypotheses that<br />

maternal bone Pb burden is<br />

associated with increasing<br />

maternal whole PbB and plasma<br />

Pb over the 3 trimesters <strong>of</strong><br />

pregnancy and that this association<br />

is modified by rates <strong>of</strong> maternal<br />

bone resorption. Urine was<br />

analyzed <strong>for</strong> cross-linked Ntelopeptides<br />

(NTx) <strong>of</strong> type I<br />

collagen, a biomarker <strong>of</strong> bone<br />

resorption. Patella and tibia Pb at<br />

1 mo postpartum. Mixed models.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Participants (n = 193):<br />

PbB (µg/dL): initial 7.10 (±1.72), 1st trimester 6.47 (± 0.17), 2nd<br />

trimester5.80 (± 0.17), 3rd trimester 6.05 (± 0.17).<br />

Plasma (µg/L): 1st trimester 0.13 (±1.88), 2nd trimester 0.12 (± 1.95), 3rd<br />

trimester 0.12 (± 1.88) (geometric means and SD)<br />

Bone Pb during pregnancy:<br />

Tibia 11.35 (±8.82, adjusted <strong>for</strong> negative values), patella 13.82 (±10.97,<br />

adjusted <strong>for</strong> negative values).<br />

Nonparticipants (n = 134):<br />

PbB 6.82 (±1.75), tibia 13.71 (±9.17, adjusted <strong>for</strong> negative values), patella<br />

11.79 (±9.75, adjusted <strong>for</strong> negative values).<br />

Found an increasing trend <strong>for</strong> plasma Pb among women with the highest<br />

bone Pb ($median level <strong>of</strong> 12.1 µg/g) but a decreasing trend among lessexposed<br />

women(below the median level). The observed increase reached its<br />

maximum among women with both the highest bone Pb and the highest<br />

bone resorption. In comparison with women with a low bone Pb and a high<br />

NTx level, those with a high bone Pb and a high NTx level had, on average,<br />

an 80% higher mean plasma Pb. In the cross-sectional analyses <strong>for</strong> each<br />

trimester <strong>of</strong> pregnancy, there was an increasingly stronger association<br />

between bone Pb and plasma Pb (log-trans<strong>for</strong>med) as pregnancy progressed.<br />

An increase in patella lead <strong>of</strong> 10 µg/g would be associated with 9% (p =<br />

0.07), 24% (p < 0.01), and 25% (p < 0.01) increases in plasma Pb in the 1st,<br />

2nd, and 3rd trimesters <strong>of</strong> pregnancy, respectively. The corresponding<br />

values <strong>for</strong> tibia lead were 8% (p = 0.16), 19% (p < 0.01), and 13% (p =<br />

0.01), respectively. Dietary calcium intake was inversely associated with<br />

plasma lead.<br />

They concluded that the results<br />

support the hypothesis <strong>of</strong> a<br />

biologic interaction between<br />

bone Pb burden and bone<br />

resorption. They also suggest<br />

that as pregnancy progresses,<br />

bone Pb may be mobilized<br />

increasingly into plasma.


AX4-29<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico (cont’d)<br />

Moline et al. (2000)<br />

Morelos, Mexico<br />

1999<br />

PbB = blood lead.<br />

Table AX4-7 (cont’d). Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects<br />

Pilot study to assess the body<br />

burden <strong>of</strong> lead in 24 Mexican<br />

women (age 21-34 yr) who were<br />

lactating. Demographic and<br />

reproductive characteristics <strong>of</strong><br />

women and potential sources <strong>of</strong><br />

lead exposure were gathered by a<br />

direct interview. Multiple<br />

regression. Average time <strong>of</strong><br />

lactation 22 (±17) months.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

PbB 4.6 (± 2.0, geometric mean), tibia 9.2 (±4.2), patella 14.8 (±8.0),<br />

calcaneus 11.7 (±11.2). An inverse relationship was noted between months<br />

<strong>of</strong> lactation and age-adjusted calcaneus lead level (p = 0.001).<br />

No association was observed between age-adjusted patella or tibia lead level<br />

and months <strong>of</strong> lactation (p = 0.15).<br />

This pilot study provides further<br />

limited evidence <strong>for</strong> the<br />

hypothesis that Pb mobilization<br />

occurs during lactation.


AX4-30<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States<br />

Hu et al. (1996)<br />

Boston, MA<br />

1991+<br />

Kim et al. (1997)<br />

Boston, MA<br />

1991-95<br />

Cheng et al. (1998)<br />

Boston, MA<br />

1991-95<br />

Table AX4-8. Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects<br />

Normative Aging Study.<br />

Subjects were middle-aged and<br />

elderly men who had community<br />

(nonoccupational) exposures to lead.<br />

Cross-sectional. Backwards<br />

elimination multivariate regression<br />

models that considered age, race,<br />

education, retirement status, measures<br />

<strong>of</strong> both current and cumulative<br />

smoking, and alcohol consumption.<br />

Normative Aging Study (n = 70).<br />

Aim to examine age and secular<br />

trends in bone and PbB levels <strong>of</strong><br />

community-exposed men aged 52-83<br />

yr. Bone and PbB levels measured<br />

twice, with a 3-yr interval.<br />

Normative Aging Study (n = 747).<br />

Aim to examine relationships <strong>of</strong><br />

nutritional factors to body Pb burden.<br />

Cross-sectional.<br />

Multiple regression models adjusting<br />

<strong>for</strong> age, education level, smoking, and<br />

alcohol consumption.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

47-59 yr: (n = 116): PbB 5.8 (±3.7), tibia 14.6 (±8.3),<br />

patella 23.6 (±12.4)<br />

60-69 yr: (n = 360): PbB 6.3 (±4.2), tibia 21.1<br />

(±11.4), patella 30.5 (±16.9)<br />

>70 yr: (n = 243): PbB 6.5 (±4.5), tibia 27 (±15.6),<br />

patella 38.8 (±23.5)<br />

PbB 6.7 (±1.8), tibia 17.5 (±2.0), patella 29.1 (±1.8)<br />

3 yr later: PbB 5.1 (±1.4), tibia 17.9 (±1.7), patella<br />

22.2 (±1.8)<br />

PbB 6.2 (± 4.1), tibia 21.9 (± 13.3), patella<br />

32.0 (±19.5).<br />

Multiple regression models men in the lowest quintile<br />

<strong>of</strong> total dietary intake levels <strong>of</strong> vitamin D (including<br />

vitamin supplements) (


AX4-31<br />

Table AX4-8 (cont’d). Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States (cont’d)<br />

Hu et al. (2001)<br />

Boston, MA<br />

1991+<br />

Oliveira et al. (2002)<br />

Boston, MA<br />

1991-98<br />

Normative Aging Study. Aim to<br />

determine if ALAD polymorphism is<br />

associated with altered levels <strong>of</strong> lead<br />

in bone and blood. Multivariate<br />

linear regression models controlling<br />

<strong>for</strong> age, education, smoking, alcohol<br />

ingestion, and vitamin D intake.<br />

Normative Aging Study.<br />

To determine if seasonal fluctuations<br />

in PbB levels are related to increased<br />

mobilization <strong>of</strong> bone Pb stores during<br />

the winter months. Measurements <strong>of</strong><br />

blood and bone Pb during the high<br />

sun exposure months <strong>of</strong> May-August<br />

(summer; n = 290); the intermediate<br />

sun exposure months <strong>of</strong> March, April,<br />

September, and October (spring/fall;<br />

n = 283); and the low sun exposure<br />

months <strong>of</strong> November-February<br />

(winter; n = 191).<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

ALAD 1-1 (n = 608): PbB 6.3(±4.1), tibia 22.2<br />

(±13.9), patella 32.2 (±19.9)<br />

ALAD 1-2/2-2 (n = 118): PbB 5.7 (±4.2), tibia 21.2<br />

(±10.9), patella 30.4 (±17.2)<br />

ALAD 1- 1 genotype was associated with cortical<br />

bone lead levels that were 2.55 µg/g (95% CI: 0.05,<br />

5.05) higher than those <strong>of</strong> the variant allele carriers.<br />

Mean PbB levels were slightly lower in summer<br />

(5.8 ± 3.4 µg/dL) compared with winter (6.6 ± 4.7<br />

µg/dL). Mean bone Pb levels were higher during the<br />

summer than the winter months: 23.9 (±15.2) and<br />

20.3 (±11.3) µg/g respectively <strong>for</strong> the tibia and<br />

34.3 (±22.8) and 29.0 (±16.2) µg/g respectively <strong>for</strong><br />

patella.<br />

No significant differences by genotype with respect<br />

to Pb levels in trabecular bone or blood. In<br />

stratified analyses and a multivariate regression<br />

model that tested <strong>for</strong> interaction, the relationship<br />

<strong>of</strong> trabecular bone Pb to PbB appeared to be<br />

significantly modified by ALAD genotype, with<br />

variant allele carriers having higher PbB levels, but<br />

only when trabecular bone Pb levels >60 µg/g.<br />

The authors suggest that the variant ALAD-2 allele<br />

modifies lead kinetics possibly by decreasing lead<br />

uptake into cortical bone and increasing the<br />

mobilization <strong>of</strong> lead from trabecular bone.<br />

Found a significant interaction between season and<br />

bone Pb with bone Pb during the winter months<br />

exerting an almost 2-fold greater influence on PbB<br />

levels than during the summer months. The<br />

authors attributed this to increased mobilization <strong>of</strong><br />

endogenous bone Pb stores arising potentially from<br />

decreased exposure to sunlight, lower levels <strong>of</strong><br />

activated vitamin D and enhanced bone resorption.


AX4-32<br />

Table AX4-8 (cont’d). Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States (cont’d)<br />

Korrick et al. (2002)<br />

Boston, MA<br />

1990-95<br />

Tsaih et al. (1999)<br />

Boston, MA<br />

1991-97<br />

Wright et al. (2004)<br />

Boston, MA<br />

1991-97<br />

Nurses’ Health Study.<br />

Cross-sectional study <strong>of</strong> 264 elderly<br />

women; 46-54 yr (80) 55-64 yr (102),<br />

65-74 yr (82). Tibia and patella Pb.<br />

Multivariate linear regression models.<br />

Normative Aging Study.<br />

Aim to evaluate hypothesis that bone<br />

and erythrocyte Pb make independent<br />

contributions to urine Pb excreted<br />

over 24 hour. Urine used as a proxy<br />

<strong>for</strong> plasma Pb.<br />

Age range 53-82 yr (n = 71).<br />

Generalized additive model.<br />

Normative Aging Study. Aim to<br />

evaluate if hemochromatosis gene<br />

(HFE) was associated with body lead<br />

burden. Tibia and patella bone Pb.<br />

DNA samples genotyped.<br />

Multivariate linear regression<br />

analyses.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

46-54 yr: PbB 2.7 (SE ±0.3), tibia 10.5 (±1.0), patella<br />

14.9 (±1.2)<br />

55-64 yr: PbB 3.4 (±0.2), tibia 12.7 (±0.9), patella<br />

17.0 (±1.1)<br />

65-74 yr: PbB 3.3 (±0.3), tibia 16.4 (±0.9), patella<br />

19.8 (±1.2).<br />

An increase from the first to the fifth quintile <strong>of</strong> tibia<br />

Pb level (19 µg/g) was associated with a 1.7 µg/dL<br />

increase in PbB (p = 0.0001).<br />

PbB: 5.94 (±3.0), tibia 21.7 (±10.9), patella 31.1<br />

(±15.1), urinary Pb 5.69 (±1.9) Fg/day. Both<br />

erythrocyte Pb and bone Pb variables remained<br />

independently and significantly associated with<br />

urinary Pb.<br />

Of 730 subjects, 94 (13%) carried the C282Y<br />

variant and 183 (25%) carried the H63D variant.<br />

In multivariate analyses that adjusted <strong>for</strong> age,<br />

smoking, and education, having an HFE variant allele<br />

was an independent predictor <strong>of</strong> significantly lower<br />

patella Pb levels (p < 0.05).<br />

Tibia and patella Pb values were significantly and<br />

positively associated with PbB but only among<br />

postmenopausal women who were not using<br />

estrogens. Older age and lower parity were<br />

associated with higher tibia Pb; only age was<br />

associated with patella Pb. They suggested the<br />

observed interaction <strong>of</strong> bone Pb with estrogen<br />

status in determining PbB supports the hypothesis<br />

that increased bone resorption, as occurs<br />

postmenopausally because <strong>of</strong> decreased estrogen<br />

production, results in heightened release <strong>of</strong> bone Pb<br />

stores into blood.<br />

Finding suggests that bone influences plasma Pb in<br />

a manner that is independent <strong>of</strong> the influence <strong>of</strong><br />

erythrocytic lead on plasma Pb. Rein<strong>for</strong>ces<br />

superiority <strong>of</strong> bone Pb over PbB in predicting some<br />

chronic <strong>for</strong>ms <strong>of</strong> toxicity may be mediated through<br />

bone's influence on plasma Pb. Urinary lead might<br />

be useful as a proxy <strong>for</strong> plasma Pb.<br />

Suggested that HFE variants have altered kinetics<br />

<strong>of</strong> Pb accumulation after exposure and these effects<br />

may be mediated by alterations in Pb toxicokinetics<br />

via iron metabolic pathways regulated by the HFE<br />

gene product and body iron stores.


AX4-33<br />

Table AX4-8 (cont’d). Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States (cont’d)<br />

Lin et al. (2004)<br />

Boston, MA<br />

1999-2000<br />

Berkowitz et al.<br />

(2004)<br />

New York<br />

1994-99<br />

Schafer et al.<br />

(2005)<br />

Baltimore, MD<br />

Community <strong>Lead</strong> Study. Measured PbB<br />

and bone Pb levels among minority<br />

individuals from Boston. Compared with<br />

earlier studies <strong>of</strong> predominantly white<br />

subjects, the 84 volunteers in this study<br />

(33:67 male to female ratio; 31-72 yrs <strong>of</strong><br />

age) had similar educational,<br />

occupational, and smoking pr<strong>of</strong>iles and<br />

mean blood, tibia, and patella Pb levels.<br />

LOWESS smoothing curves. Multiple<br />

linear regression analyses to predict<br />

blood, tibia and patella Pb.<br />

Longitudinal study <strong>of</strong> 91 premenopausal<br />

and perimenopausal women aged<br />

$ 30 yrs <strong>of</strong> age from New York who<br />

were undergoing surgical menopause<br />

(baseline; n 84) to determine if bone Pb<br />

values decrease and PbB values increase<br />

during menopause. Tibia Pb<br />

concentrations measured at baseline, 6<br />

mo (70) and 18 mo (62) post surgery.<br />

Evaluated the relations among PbB, tibia<br />

Pb, and homocysteine levels by crosssectional<br />

analysis among subjects in the<br />

Baltimore Memory Study, a longitudinal<br />

study <strong>of</strong> 1, 140 randomly selected<br />

residents in Baltimore, MD, aged 50-70<br />

yr and 66.0% female, 53.9% white, and<br />

41.4% black or African American.<br />

Multiple linear regression analyses.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />


AX4-34<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

United States (cont’d)<br />

Kosnett et al.<br />

(1994)<br />

Dickson City, PA<br />

Popovic et al.<br />

(2005)<br />

Bunker Hill, ID<br />

1994<br />

Canada<br />

Webber et al.<br />

(1995)<br />

Canada<br />

Unknown<br />

Table AX4-8 (cont’d). Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects<br />

Aim to determine the influence <strong>of</strong><br />

demographic, exposure and medical<br />

factors on the bone Pb concentration <strong>of</strong><br />

subjects with environmental Pb exposure.<br />

101 subjects (49 males, 52 females; aged<br />

11 to 78 yrs) recruited from 49 <strong>of</strong> 123<br />

households geographically located in a<br />

suburban residential neighborhood.<br />

108 <strong>for</strong>mer female smelter employees<br />

and 99 referents to assess the PbB versus<br />

bone Pb relationship.<br />

Tested hypothesis that women on<br />

hormone replacement therapy should<br />

have higher bone Pb content and lower<br />

plasma Pb as hormone replacement<br />

therapy would suppress the transfer <strong>of</strong><br />

endogenous Pb to the circulation.<br />

56 women, some using hormone<br />

replacement therapy over ~4 yrs.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

Log-trans<strong>for</strong>med bone Pb highly correlated with age<br />

(r = 0.71; p # 0.0001).<br />

Exposed: PbB 2.73 (±2.39), tibia 14.4 (±0.5)<br />

Referents: PbB 1.25 (±2.10), tibia 3.22 (±0.50)<br />

Pb concentrations in tibia and blood significantly<br />

higher in the exposed group. Endogenous release rate<br />

(µg Pb per dL blood/ µg Pb/g bone) in<br />

postmenopausal women was double the rate found<br />

in premenopausal women (0.132 ± 0.019 versus<br />

0.067 ± 0.014).<br />

Low dose hormone replacement therapy (n = 15):<br />

PbB 4.08 (±1.60), tibia 19.37 (±8.62), calcaneus 24.02<br />

(±10.88)<br />

Moderate dose hormone replacement therapy (n = 11):<br />

PbB 5.22 (±3.36), tibia 16.80 (±11.68), calcaneus<br />

23.83 (±14.18)<br />

Calcium only (n = 22): PbB 4.6 (±1.59), tibia 11.13<br />

(±6.22), calcaneus 21.12 (±13.55)<br />

Bone Pb showed no significant change up to age<br />

20 yr, increased with the same slope in men and<br />

women between ages 20 and 55 yr, and then<br />

increased at a faster rate in men older than 55 yr.<br />

Higher tibia bone Pb (and PbB) was associated<br />

with use <strong>of</strong> estrogen (present or <strong>for</strong>mer) in both the<br />

whole referent group and postmenopausal women<br />

in the referent group.<br />

Women not taking hormones had significantly<br />

lower Pb values in cortical bone compared to<br />

all women on hormone replacement therapy<br />

(p = 0.007). Showed higher tibia Pb levels but no<br />

increase in calcaneus Pb level or decrease in PbB.


AX4-35<br />

Table AX4-8 (cont’d). Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects<br />

Reference, Study<br />

Location, and<br />

Period Study Description<br />

Mexico<br />

Garrido-Latorre<br />

et al. (2003)<br />

Mexico City<br />

1995<br />

Australia<br />

Gulson et al.<br />

(2002)<br />

Sydney, Australia<br />

2000<br />

PbB = blood lead.<br />

Aim was to examine the relationship <strong>of</strong><br />

PbB levels to menopause and bone lead<br />

levels in 232 perimenopausal and<br />

postmenopausal women from Mexico<br />

City. Measured bone mineral density in<br />

addition to bone Pb. In<strong>for</strong>mation<br />

regarding reproductive characteristics<br />

and known risk factors <strong>for</strong> PbB was<br />

obtained using a standard questionnaire<br />

by direct interview. Mean age <strong>of</strong> the<br />

population was 54.7 yrs (±9.8). Linear<br />

regression analyses.<br />

Environmentally exposed females (n = 7)<br />

and males (n = 3) aged 44-70 yr. Treated<br />

<strong>for</strong> 6 mo with the bisphosphonate<br />

alendronate. PbB and isotopic ratios<br />

measured by TIMS <strong>for</strong> 6 mo prior to<br />

treatment and 12 mo post-treatment.<br />

Bone mineral density and bone markers<br />

including NT x measured.<br />

<strong>Lead</strong> Measurement (SD or range)<br />

PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation<br />

PbB 9.2 (±4.7), tibia 14.85 (±10.1), patella 22.73<br />

(±14.9).<br />

A change <strong>of</strong> 10 µg Pb/g bone mineral in<br />

postmenopausal subjects was associated with an<br />

increase in PbB <strong>of</strong> 1.4 µg/dL, whereas a similar<br />

change in bone lead among premenopausal women<br />

was associated with an increase in PbB <strong>of</strong> 0.8 µg/dL.<br />

Found a decrease in PbB concentrations and changing<br />

PbB isotopic composition in the direction predicted<br />

during treatment. Upon cessation <strong>of</strong> treatment, PbB<br />

increased and the isotopic compositions changed.<br />

Found that postmenopausal women using hormone<br />

replacement therapy had lower PbB levels and<br />

higher tibia and patella bone Pb levels than nonusers;<br />

patella Pb explained the greatest part <strong>of</strong><br />

variations in PbB. Found no association with PbB<br />

levels and did not describe any relationships<br />

between bone lead and bone density.<br />

Results consistent with changes in bone remodeling<br />

associated with bisphosphonate use.


AX4-36<br />

Table AX4-9. <strong>Lead</strong> in Deciduous Teeth from Urban and Remote Environments<br />

Reference, Study<br />

Location, and Period Study Description <strong>Lead</strong> Measurement Findings, Interpretation<br />

Canada<br />

Tsuji et al. (2001)<br />

Ontario, Canada<br />

Europe<br />

Tvinnereim et al.<br />

(1997)<br />

Norway<br />

1990-94<br />

Lyngbye et al. (1991)<br />

Denmark<br />

Gil et al. (1996)<br />

Coruna, Spain<br />

Nowak and<br />

Chmielnicka (2000)<br />

Poland<br />

Dentine chips from schoolchildren living<br />

in a remote area.<br />

Mean value <strong>of</strong> 9.2 µg/g dry weight (n = 61) Attributed the high values to consumption <strong>of</strong><br />

lead contaminated game meat.<br />

2,746 deciduous whole teeth. Mean 1.27 ± 1.87 µg/g <strong>of</strong> dry tooth substance Observed an ~50% reduction in lead<br />

concentrations since the 1970s.<br />

In 2,033 teeth from 1, 848 children. Geometric mean <strong>for</strong> the largest group from Arhus to<br />

be 8.4 µg/g (wet weight) with similar values from<br />

Copenhagen suburbs with a secondary lead smelter<br />

(9.6 µg/g) and a lead battery factory (9.9 µg/g).<br />

220 whole deciduous and permanent teeth<br />

(one per subject).<br />

Compared permanent teeth from two<br />

cohorts, one from the highly polluted<br />

Katowice district and a control town <strong>of</strong><br />

Beskid.<br />

Permanent teeth showed higher mean values<br />

(13.1 ±1.1 µg/g) than deciduous teeth (4.0 ± 1.1 µg/g)<br />

In the control teeth, they observed decreases in lead<br />

<strong>for</strong> incisors (41.8 µg/g) to canines (37.5 µg/g) to<br />

molars (35.3 µg/g) to premolars (32.0 µg/g).<br />

However, there was no difference in the mean values<br />

<strong>for</strong> the two centers: Katowice 36.5 ± 16.3 µg/g and<br />

Beskid 36.3 ± 11.5 µg/g.<br />

Concluded that automobile<br />

exhausts and indirect occupational<br />

exposure were important sources<br />

<strong>for</strong> the lead in dentine.<br />

Found no gender differences.<br />

These values are very high compared with<br />

most other studies.


AX4-37<br />

Table AX4-9 (cont’d). <strong>Lead</strong> in Deciduous Teeth from Urban and Remote Environments<br />

Reference, Study<br />

Location, and Period Study Description <strong>Lead</strong> Measurement Findings, Interpretation<br />

Mexico<br />

Hernandez-Guerrero<br />

et al. (2004)<br />

Mexico City<br />

Frank et al. (1990)<br />

Alsace, Mexico<br />

Asia<br />

Karakaya et al. (1996)<br />

Ankara, Turkey<br />

100 healthy deciduous teeth collected<br />

from 2 to 13 yr old children.<br />

Circular biopsies 500 Fm in diameter<br />

punched in the vertical sections <strong>of</strong> the<br />

crown and cervical third <strong>of</strong> each root. The<br />

age <strong>of</strong> the European subjects ranged from<br />

10 to 80 yrs in Europe and 12 to 29 yrs in<br />

Mexico City. Energy-dispersive X-ray<br />

fluorescence method to compare lead in<br />

enamel and dentine <strong>of</strong> premolars and<br />

permanent molars.<br />

103 whole deciduous teeth from primary<br />

school aged children aged 7 to 12 yrs.<br />

Higher mean concentrations <strong>of</strong> lead in the 10-13 yr<br />

old group (7.7 µg/g) than in other age groups and the<br />

mean concentrations were higher in girls (7.3 µg/g)<br />

than boys (6.3 µg/g).<br />

Compared with the European values, there were<br />

~6 times higher inner coronal dentine and 7 to<br />

9 times higher pulpal root dentine concentrations<br />

<strong>for</strong> samples from Mexico City.<br />

Significant differences in lead <strong>for</strong> urban (4.99 ± 0.46<br />

µg/g dry weight) compared with suburban children<br />

(1.69 ± 0.25 µg/g).<br />

No association between pollution intensity<br />

and tooth lead.<br />

The authors found no significant difference in<br />

the relationship between traffic and mean lead<br />

values <strong>for</strong> enamel and dentine in the European<br />

communities but a significantly higher lead<br />

concentration in relation to age. The<br />

differences were attributed to traffic exposure.


AX4-38<br />

Table AX4-10. <strong>Lead</strong> in Deciduous Teeth from Polluted Environments<br />

Reference, Study<br />

Location, and Period Study Description <strong>Lead</strong> Measurement Findings, Interpretation<br />

Europe<br />

Begerow et al. (1994)<br />

Germany<br />

1991<br />

Cikrt et al. (1997)<br />

Czech Republic<br />

Australia<br />

Gulson (1996)<br />

Broken Hill, Australia<br />

Gulson et al. (2004)<br />

Lake Macquarie,<br />

Australia<br />

PbB = blood lead.<br />

790 children aged 6 yrs old living in<br />

urban and rural areas in western and<br />

eastern Germany. Incisors sampled.<br />

Compared tooth (n = 162) and PbB levels<br />

in children living at various distances<br />

from a lead smelter.<br />

36 exposed and nonexposed children<br />

from Broken Hill lead-zinc mining<br />

community. Sectioned teeth into mainly<br />

enamel (incisal section) and mainly<br />

dentine (cervical section). <strong>Lead</strong> isotope<br />

ratios and lead concentrations by TIMS<br />

with isotope dilution.<br />

10 children from six houses in a primary<br />

zinc-lead smelter community at North<br />

Lake Macquarie, New South Wales,<br />

Australia. Sectioned deciduous teeth<br />

compared with environmental samples.<br />

<strong>Lead</strong> isotope ratios and lead<br />

concentrations by TIMS with isotope<br />

dilution.<br />

<strong>Lead</strong> levels <strong>of</strong> 1.50 to 1.74 µg/g from the western sector<br />

and from 1.51 to 2.72 µg/g in the eastern sector.<br />

Significant difference in the mean tooth lead <strong>for</strong> children<br />

from the most contaminated zone less than 0.5 km from the<br />

smelter (6.44 µg/g; n = 13) and those >5 km from the<br />

smelter (1.45 µg/g; n = 36). PbB levels varied from 15.42<br />

µg Pb/100 ml (n = 6; 95% CI: 7.17, 33.17) close to the<br />

smelter to 4.66 µg/100 ml (n = 165, 95% CI: 4.30, 5.04) at<br />

larger distances.<br />

For subjects with low exposure (n = 13), lead<br />

concentrations in the incisal section ranged from 0.4 to 3.5<br />

µg/g with a mean and standard deviation <strong>of</strong> 1.2 ± 0.8 µg/g<br />

(n = 13). For the cervical sections in low exposure<br />

children, the values ranged from 0.8 to 8.3 and mean<br />

3.7 ± 2.4 µg/g. For subjects with high exposure (n = 23),<br />

lead concentrations in the incisal section ranged from 1.0 to<br />

8.9 µg/g with a mean and standard deviation <strong>of</strong> 2.6 ± 1.8<br />

µg/g. For the cervical sections in high exposure children<br />

the values ranged from 1.5 to 31.5 µg/g and mean 13.7<br />

± 8.0 µg/g.<br />

PbB levels in the children ranged from 10 to 42 µg/dL and<br />

remained elevated <strong>for</strong> a number <strong>of</strong> years. Median lead<br />

level in the enamel section <strong>of</strong> the teeth was 2.3 µg/g with a<br />

range from 0.6 to 7.4 µg/g; in dentine the median value was<br />

5.3 µg/g with a range from 1.4 to 19.9 µg/g.<br />

Major decrease (40-50%) since 1976.<br />

No descriptions <strong>of</strong> the teeth type were<br />

available.<br />

The isotopic results in dentine were<br />

interpreted to reflect an increased lead<br />

exposure from the lead-zinc-silver<br />

orebody during early childhood, probably<br />

associated with hand-to-mouth activity.<br />

Approximately 55 to 100% <strong>of</strong> lead could<br />

be derived from the smelter.


AX4-39<br />

Table AX4-11. Summary <strong>of</strong> Selected Measurements <strong>of</strong> Urine <strong>Lead</strong> Levels in Humans<br />

Reference, Study<br />

Location, and Period Study Description Urine <strong>Lead</strong> Measurement Comment<br />

United States<br />

CDC (2005)<br />

U.S.<br />

1999-2002<br />

Schwartz et al.<br />

(1999, 2000b)<br />

U.S.<br />

1993-1997<br />

Rabinowitz et al.<br />

(1976)<br />

New York<br />

NR<br />

Design: national survey (NHANES IV)<br />

stratified, multistage probability cluster design<br />

Subjects: children and adults ($6 yrs, n = 5140)<br />

in general population<br />

Biomarker measured: urine lead<br />

Analysis: ICP-MS<br />

Design: prospective<br />

Subjects: adult male (n = 543) <strong>for</strong>mer TEL<br />

manufacture workers (age range: 42-74 yrs)<br />

Biomarker measured: DMSA (10 mg/kg)provoked<br />

urine lead<br />

Analysis: GFAAS<br />

Design: experimental study<br />

Subjects: adult (n:5) males, age range 25-53 yrs,<br />

ingested 300 µg Pb/day (~50% as 204 Pb) <strong>for</strong><br />

10-210 days<br />

Biomarker measured: urine lead<br />

Analysis: MS<br />

Units: µg/g creatinine<br />

Geometric mean (95% CI)<br />

Age (yr) 1999-2000 2001-2002<br />

$6: 0.72 (0.70, 0.74) 0.64 (0.60, 0.68)<br />

n: 2465 2689<br />

6-11: 1.17 (0.98, 1.41) 0.92 (0.84, 1.00)<br />

n: 340 368<br />

12-19: 0.50 (0.46, 0.54) 0.40 (0.38, 0.43)<br />

n: 719 762<br />

$20: 0.72 (0.68, 0.76) 0.66 (0.621, 0.70)<br />

n: 1406 1559<br />

Males: 0.72 (0.68, 0.76) 0.64 (0.61, 0.67)<br />

n: 1227 1334<br />

Females: 0.72 (0.68, 0.76) 0.64 (0.59, 0.69)<br />

n: 1238 1355<br />

Units: µg/4 hr<br />

Arithmetic mean (SD):<br />

$2 yr exposure: 17.1 (15.7)<br />


AX4-40<br />

Table AX4-11 (cont’d). Summary <strong>of</strong> Selected Measurements <strong>of</strong> Urine <strong>Lead</strong> Levels in Humans<br />

Reference, Study<br />

Location, and Period Study Description Urine <strong>Lead</strong> Measurement Comment<br />

United States (cont’d)<br />

Berger et al. (1990)<br />

Ohio<br />

1983-1986<br />

Europe<br />

Chamberlain et al.<br />

(1978)<br />

United Kingdom<br />

1975-1976<br />

Brockhaus et al. (1988)<br />

Germany<br />

1982-1986<br />

Koster et al. (1989)<br />

Germany<br />

NR<br />

Australia<br />

Gulson et al. (2000)<br />

Australia<br />

Design: cross-sectional, convenience sample<br />

Subjects: children (n = 39), age range not reported.<br />

Biomarker measured: timed urine lead<br />

Analysis: AAS<br />

Design: experimental<br />

Subjects: adult males (n = 6), intravenous injection<br />

<strong>of</strong> 203 Pb tracer<br />

Biomarker: urinary lead clearance<br />

Analysis: gamma spectrometer ( 203 Pb)<br />

Design: cross-sectional<br />

Subjects: children (n = 184), age range 4-11 yrs<br />

residing in 2 areas impacted by smelting operations<br />

Biomarker measured: urine lead<br />

Analysis: GFAAS<br />

Design: cross-sectional<br />

Subjects: adult (n = 46, 40 males) hospital<br />

workers, age range 20-78 yr.<br />

Biomarker measured: urine lead<br />

Analysis: GFAAS<br />

Design: longitudinal<br />

Subjects: women (n = 58) during pregnancy,<br />

age range 18-35 yrs<br />

Biomarker measured: blood-to-urine clearance<br />

Analysis: TIMS<br />

Units: µg/day<br />

range: 5-70<br />

Units: L/day<br />

Arithmetic mean (range)<br />

Blood-to-urine: 0.09 (0.08-0.10)<br />

Plasma-to-urine: 20<br />

Units: µg/g creatinine<br />

Geometric mean (GSD, range)<br />

Stolberg (n = 106): 9.6 (2.3, 0.2-43.0)<br />

Dortmund (n = 78): 6.7 (2.0, 1.6-41.0)<br />

Units: µg/24 hr-1.73 m 2 (adult body surface area)<br />

Arithmetic mean (range): 6.8 (2.3-18.9)<br />

Units: µg/h<br />

Arithmetic mean (SD, range): 3.2 (0.8-10.2)<br />

Geometric mean: 2.7<br />

PbB range was 22-55 µg/dL. Blood-to<br />

urine clearance estimate was 0.07 L/day<br />

(from Diamond, 1992).<br />

Geometric mean PbB levels were<br />

~7 µg/dL.<br />

Arithmetic mean (range) PbB (µg/dL)<br />

was 7.6 (2.6-18.7).<br />

Blood-to-urine clearance estimate was<br />

0.15 L/day (from Diamond, 1992).<br />

Reported blood-to-urine clearance<br />

corresponds to ~0.08 L/day.


AX4-41<br />

Table AX4-11 (cont’d). Summary <strong>of</strong> Selected Measurements <strong>of</strong> Urine <strong>Lead</strong> Levels in Humans<br />

Reference, Study<br />

Location, and Period Study Description Urine <strong>Lead</strong> Measurement Comment<br />

Asia<br />

Araki et al. (1986,<br />

1990)<br />

Japan<br />

NR<br />

Lee et al. (1990)<br />

Korea<br />

NR<br />

Schwartz et al.<br />

(2000a), Lee et al.<br />

(2001)<br />

Korea<br />

1997-1999<br />

Design: cross-sectional<br />

Subjects: adult (n = 19) male, gun metal foundry<br />

workers, age range 34-59 yr.<br />

Biomarker measured: urine lead<br />

Analysis: AAS<br />

Design: cross-sectional<br />

Subjects: adults (n = 95) male workers in lead<br />

smelting, battery manufacture, PVC-stabilizer<br />

manufacture facilities, age range: 19-64 yrs;<br />

reference subjects (n = 13), age range 22-54 yr.<br />

Biomarker measured: DMSA (10 mg/kg)provoked<br />

urine lead<br />

Analysis: GFAAS<br />

Design: Cross-sectional<br />

Subjects: Adult lead (inorganic) workers<br />

(n = 798, 634 males), age range 18-65 yrs.<br />

Biomarker measured: MSA (10 mg/kg)-provoked<br />

urine lead<br />

Analysis: GFAAS<br />

Units: µg/24 hr<br />

Arithmetic mean (range): 94 (37-171)<br />

Units: µg/4 hr<br />

Arithmetic mean (SD, range)<br />

<strong>Lead</strong> workers: 288.7 (167.7, 32.4-789)<br />

Reference: 23.7 (11.5, 10.5-43.5)<br />

Units: µg/4 hr<br />

Arithmetic mean (SD, range)<br />

186 (208, 4.8-2100)<br />

Arithmetic mean plasma concentration<br />

was 0.67 µg/dL (range 0.37-0.92).<br />

Plasma-to urine clearance estimate was<br />

22 L/day.<br />

Blood-to-urine clearance estimate was<br />

0.33 L/day (from Diamond, 1992).<br />

Arithmetic mean (SD, range) PbB<br />

concentration (µg/dL) was 44.6 (12.6,<br />

21.4-78.4) in lead workers and 5.9 (1.2,<br />

4.0-7.2) in reference subjects.<br />

PbB was strongest predictor or DMSAprovoked<br />

urine lead.<br />

Arithmetic mean (SD, range) PbB<br />

(µg/dL) was 32.0 (15, 4-86). PbB was<br />

strongest predictor or DMSA-provoked<br />

urine lead.<br />

Arithmetic mean (SD, range) tibia lead<br />

(µg/g, XRF) was 37.1 (40.4, -7 to 338).<br />

AAS - atomic absorption spectroscopy; PbB = blood lead; ET-AAS - electro-thermal atomic absorption spectrometry; GFAAS - graphite furnace atomic absorption<br />

spectroscopy; ICP-AES - inductively coupled plasma/atomic emission spectroscopy; ICP-MS - inductively coupled plasma-mass spectrometry; MS - mass spectrometry;<br />

NR - not reported; Pct - percentile; TEL -tetraethyl lead; TIMS - thermal ionization mass spectrometry.


AX4-42<br />

Table AX4-12. Summary <strong>of</strong> Selected Measurements <strong>of</strong> Hair <strong>Lead</strong> Levels in Humans<br />

Reference, Study<br />

Location, and<br />

Period Study Description Hair <strong>Lead</strong> Measurement Comment<br />

United States<br />

DiPietro et al.<br />

(1989)<br />

GA, SC, TX, VA<br />

1976-1980<br />

Tuthill (1996)<br />

MA<br />

NR<br />

Europe<br />

Annesi-Maesano<br />

et al. (2003)<br />

France<br />

1985, 1991-1992<br />

Drasch et al. (1997)<br />

Germany<br />

1993-1994<br />

Gerhardsson et al.<br />

(1995b)<br />

Sweden<br />

NR<br />

Design: Cross-sectional (random sample from NHANES<br />

<strong>II</strong>, HHANES Stands)<br />

Subjects: adults (n = 270, 200 males; age range:<br />

20-73 yrs) from general population<br />

Biomarker measured: Hair lead<br />

Analysis: ICP-AES<br />

Design: Cross-sectional<br />

Subjects: children (n = 277, 141 males,<br />

age range 6.5-7.5 yrs)<br />

Biomarker measured: Hair lead<br />

Analysis: ICP-AES<br />

Design: cross-sectional<br />

Subjects: mother (mean age 29 yr)-infant pairs (n:374)<br />

Biomarker measured: hair lead<br />

Analysis: ICP-AES<br />

Design: cross-sectional<br />

Subjects: adults (n = 150, 75 males; age range: 16-93<br />

yrs) from general population with no known occupational<br />

exposure<br />

Biomarker measured: hair lead (post-mortem)<br />

Analysis: ET-AAS<br />

Design: cross-sectional<br />

Subjects: adult male smelter workers (n = 32) and<br />

referents (n = 10)<br />

Biomarker measured: hair lead (post-mortem)<br />

Analysis: XRF<br />

Units: µg/g<br />

Geometric mean (10-90 th Pct range)<br />

2.42 (


AX-43<br />

Table AX4-12 (cont’d). Summary <strong>of</strong> Selected Measurements <strong>of</strong> Hair <strong>Lead</strong> Levels in Humans<br />

Reference, Study<br />

Location, and<br />

Period Study Description Hair <strong>Lead</strong> Measurement Comment<br />

Europe (cont’d)<br />

Esteban et al.<br />

(1999)<br />

Russia<br />

1996<br />

Design: cross-sectional<br />

Subjects: children (n = 189, 110 females; age rage<br />

1.9-10.6 yr) living in the vicinity <strong>of</strong> lead battery and<br />

leaded glass manufacture facilities.<br />

Biomarker measured: hair lead<br />

Analysis: ICP-AES<br />

Units: ng/g<br />

Geometric mean (range):<br />

5.4 (1-39.2)<br />

90 th Pct: ~15<br />

Geometric mean PbB was 8.5 µg/dL<br />

(range 3.1-35.7); log PbB = 1.44 + 0.35<br />

(log hair) + 0.24 (gender), r 2 = 0.20.<br />

AAS - atomic absorption spectroscopy; PbB = blood lead; ET-AAS - electro-thermal atomic absorption spectrometry; GFAAS - graphite furnace atomic absorption<br />

spectroscopy; HHANES - Hispanic Health and Nutrition Examination Survey; ICP-AES - inductively coupled plasma/atomic emission spectroscopy; ICP-MS - inductively<br />

coupled plasma-mass spectrometry; NR - not reported; Pct - percentile.


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Weis, C. P.; Lavelle, J. M. (1991) Characteristics to consider when choosing an animal model <strong>for</strong> the study <strong>of</strong> lead<br />

bioavailability. Chem. Speciation Bioavailability 3: 113-119.<br />

Weitzman, M.; Aschengrau, A.; Bellinger, D.; Jones, R.; Hamlin, J. S. (1993) <strong>Lead</strong>-contaminated soil abatement and<br />

urban children's blood lead levels. JAMA J. Am. Med. Assoc. 269: 1647-1654.<br />

Wells, A. C.; Venn, J. B.; Heard, M. J. (1977) Deposition in the lung and uptake to blood <strong>of</strong> motor exhaust labelled<br />

with 203 Pb. In: Walton, W. H.; McGovern, B., eds. Inhaled particles IV: proceedings <strong>of</strong> an international<br />

symposium, part 1; September 1975; Edinburgh, United Kingdom. Ox<strong>for</strong>d, United Kingdom: Pergamon<br />

Press, Ltd.; pp. 175-189.<br />

AX4-61


October 2006<br />

<strong>EPA</strong>/600/R-05/144bF<br />

<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong> <strong>of</strong> <strong>II</strong>


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong><br />

National Center <strong>for</strong> Environmental Assessment-RTP Division<br />

Office <strong>of</strong> Research and Development<br />

U.S. Environmental Protection Agency<br />

Research Triangle Park, NC<br />

<strong>EPA</strong>/600/R-05/144bF<br />

October 2006


PREFACE<br />

National Ambient <strong>Air</strong> <strong>Quality</strong> Standards (NAAQS) are promulgated by the United States<br />

Environmental Protection Agency (<strong>EPA</strong>) to meet requirements set <strong>for</strong>th in Sections 108 and 109<br />

<strong>of</strong> the U.S. Clean <strong>Air</strong> Act. Those two Clean <strong>Air</strong> Act sections require the <strong>EPA</strong> Administrator<br />

(1) to list widespread air pollutants that reasonably may be expected to endanger public health or<br />

welfare; (2) to issue air quality criteria <strong>for</strong> them that assess the latest available scientific<br />

in<strong>for</strong>mation on nature and effects <strong>of</strong> ambient exposure to them; (3) to set “primary” NAAQS to<br />

protect human health with adequate margin <strong>of</strong> safety and to set “secondary” NAAQS to protect<br />

against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade<br />

materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS<br />

<strong>for</strong> a given listed pollutant or class <strong>of</strong> pollutants.<br />

<strong>Lead</strong> was first listed in the mid-1970’s as a “criteria air pollutant” requiring NAAQS<br />

regulation. The scientific in<strong>for</strong>mation pertinent to Pb NAAQS development available at the time<br />

was assessed in the <strong>EPA</strong> document <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>; published in 1977. Based on<br />

the scientific assessments contained in that 1977 lead air quality criteria document (1977 <strong>Lead</strong><br />

AQCD), <strong>EPA</strong> established a 1.5 µg/m 3 (maximum quarterly calendar average) Pb NAAQS in<br />

1978.<br />

To meet Clean <strong>Air</strong> Act requirements noted above <strong>for</strong> periodic review <strong>of</strong> criteria and<br />

NAAQS, new scientific in<strong>for</strong>mation published since the 1977 <strong>Lead</strong> AQCD was later assessed in<br />

a revised <strong>Lead</strong> AQCD and Addendum published in 1986 and in a Supplement to the 1986<br />

AQCD/Addendum published by <strong>EPA</strong> in 1990. A 1990 <strong>Lead</strong> Staff Paper, prepared by <strong>EPA</strong>’s<br />

Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards (OPQPS), drew upon key findings and conclusions<br />

from the 1986 <strong>Lead</strong> AQCD/Addendum and 1990 Supplement (as well as other OAQPSsponsored<br />

lead exposure/risk analyses) in posing options <strong>for</strong> the <strong>EPA</strong> Administrator to consider<br />

with regard to possible revision <strong>of</strong> the Pb NAAQS. However, <strong>EPA</strong> chose not to revise the Pb<br />

NAAQS at that time. Rather, as part <strong>of</strong> implementing a broad 1991 U.S. <strong>EPA</strong> Strategy <strong>for</strong><br />

Reducing <strong>Lead</strong> Exposure, the Agency focused primarily on regulatory and remedial clean-up<br />

ef<strong>for</strong>ts to reduce Pb exposure from a variety <strong>of</strong> non-air sources that posed more extensive public<br />

health risks, as well as other actions to reduce air emissions.<br />

The purpose <strong>of</strong> this revised <strong>Lead</strong> AQCD is to critically assess the latest scientific<br />

in<strong>for</strong>mation that has become available since the literature assessed in the 1986 <strong>Lead</strong><br />

<strong>II</strong>-iii


AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new<br />

in<strong>for</strong>mation useful in evaluating health and environmental effects <strong>of</strong> ambient air lead exposures.<br />

This includes discussion in this document <strong>of</strong> in<strong>for</strong>mation regarding: the nature, sources,<br />

distribution, measurement, and concentrations <strong>of</strong> lead in the environment; multimedia lead<br />

exposure (via air, food, water, etc.) and biokinetic modeling <strong>of</strong> contributions <strong>of</strong> such exposures<br />

to concentrations <strong>of</strong> lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,<br />

as key indices <strong>of</strong> lead exposure).; characterization <strong>of</strong> lead health effects and associated exposureresponse<br />

relationships; and delineation <strong>of</strong> environmental (ecological) effects <strong>of</strong> lead. This final<br />

version <strong>of</strong> the revised <strong>Lead</strong> AQCD mainly assesses pertinent literature published or accepted <strong>for</strong><br />

publication through December 2005.<br />

The First External Review Draft (dated December 2005) <strong>of</strong> the revised <strong>Lead</strong> AQCD<br />

underwent public comment and was reviewed by the Clean <strong>Air</strong> Scientific Advisory Committee<br />

(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public<br />

comments and CASAC recommendations received were taken into account in making<br />

appropriate revisions and incorporating them into a Second External Review Draft (dated May,<br />

2006) which was released <strong>for</strong> further public comment and CASAC review at a public meeting<br />

held June 28-29, 2006. In addition, still further revised drafts <strong>of</strong> the Integrative Synthesis<br />

chapter and the Executive Summary were then issued and discussed during an August 15, 2006<br />

CASAC teleconference call. Public comments and CASAC advice received on these latter<br />

materials, as well as Second External Review Draft materials, were taken into account in making<br />

and incorporating further revisions into this final version <strong>of</strong> this <strong>Lead</strong> AQCD, which is being<br />

issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present<br />

document provide inputs to an associated <strong>Lead</strong> Staff Paper prepared by <strong>EPA</strong>’s Office <strong>of</strong> <strong>Air</strong><br />

<strong>Quality</strong> Planning and Standards (OAQPS), which poses options <strong>for</strong> consideration by the <strong>EPA</strong><br />

Administrator with regard to proposal and, ultimately, promulgation <strong>of</strong> decisions on potential<br />

retention or revision, as appropriate, <strong>of</strong> the current Pb NAAQS.<br />

Preparation <strong>of</strong> this document has been coordinated by staff <strong>of</strong> <strong>EPA</strong>’s National Center <strong>for</strong><br />

Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific<br />

staff, together with experts from academia, contributed to writing <strong>of</strong> document chapters. Earlier<br />

drafts <strong>of</strong> document materials were reviewed by scientists from other <strong>EPA</strong> units and by non-<strong>EPA</strong><br />

experts in several public peer consultation workshops held by <strong>EPA</strong> in July/August 2005.<br />

<strong>II</strong>-iv


NCEA acknowledges the valuable contributions provided by authors, contributors, and<br />

reviewers and the diligence <strong>of</strong> its staff and contractors in the preparation <strong>of</strong> this document. The<br />

constructive comments provided by public commenters and CASAC that served as valuable<br />

inputs contributing to improved scientific and editorial quality <strong>of</strong> the document are also<br />

acknowledged by NCEA.<br />

DISCLAIMER<br />

Mention <strong>of</strong> trade names or commercial products in this document does not constitute<br />

endorsement or recommendation <strong>for</strong> use.<br />

.<br />

<strong>II</strong>-v


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(Second External Review Draft)<br />

VOLUME I<br />

EXECUTIVE SUMMARY .........................................................................................................E-1<br />

1. INTRODUCTION ........................................................................................................... 1-1<br />

2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD.......................................... 2-1<br />

3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED<br />

ENVIRONMENTAL CONCENTRATIONS.................................................................. 3-1<br />

4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD<br />

BURDEN IN HUMANS.................................................................................................. 4-1<br />

5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS<br />

AND IN VITRO TEST SYSTEMS................................................................................. 5-1<br />

6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS<br />

ASSOCIATED WITH LEAD EXPOSURE .................................................................... 6-1<br />

7. ENVIRONMENTAL EFFECTS OF LEAD ................................................................... 7-1<br />

8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH<br />

EFFECTS INFORMATION............................................................................................ 8-1<br />

VOLUME <strong>II</strong><br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS) ............................................. AX4-1<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN<br />

LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS) ................ AX5-1<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH<br />

EFFECTS ASSOCIATED WITH LEAD EXPOSURE) ................................. AX6-1<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD).................................. AX7-1<br />

<strong>II</strong>-vi


Table <strong>of</strong> Contents<br />

Page<br />

PREFACE .................................................................................................................................. <strong>II</strong>-iii<br />

DISCLAIMER ............................................................................................................................ <strong>II</strong>-v<br />

List <strong>of</strong> Tables .............................................................................................................................. <strong>II</strong>-x<br />

Authors, Contributors, and Reviewers..................................................................................... <strong>II</strong>-xxi<br />

U.S. Environmental Protection Agency Project Team <strong>for</strong> Development <strong>of</strong> <strong>Air</strong><br />

<strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>................................................................................................. <strong>II</strong>-xxvii<br />

U.S. Environmental Protection Agency Science Advisory Board (SAB) Staff<br />

Office Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)........................................... <strong>II</strong>-xxix<br />

Abbreviations and Acronyms ................................................................................................ <strong>II</strong>-xxxi<br />

AX5. CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN<br />

LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS ................. AX5-1<br />

ANNEX TABLES AX5-2 ....................................................................................... AX5-1<br />

ANNEX TABLES AX5-3 ..................................................................................... AX5-15<br />

ANNEX TABLES AX5-4 ..................................................................................... AX5-37<br />

ANNEX TABLES AX5-5 ..................................................................................... AX5-60<br />

ANNEX TABLES AX5-6 ..................................................................................... AX5-75<br />

ANNEX TABLES AX5-7 ................................................................................... AX5-111<br />

ANNEX TABLES AX5-8 ................................................................................... AX5-121<br />

ANNEX TABLES AX5-9 ................................................................................... AX5-146<br />

ANNEX TABLES AX5-10 ................................................................................. AX5-156<br />

ANNEX TABLES AX5-11 ................................................................................. AX5-186<br />

REFERENCES .................................................................................................... AX5-190<br />

<strong>II</strong>-vii


List <strong>of</strong> Tables<br />

AX4-1 Analytical Methods <strong>for</strong> Determining <strong>Lead</strong> in Blood, Urine, and Hair ............ AX4-2<br />

AX4-2 Summary <strong>of</strong> Selected Measurements <strong>of</strong> PbB Levels in Humans .................... AX4-4<br />

AX4-3 Bone <strong>Lead</strong> Measurements in Cadavers............................................................ AX4-7<br />

AX4-4 Bone <strong>Lead</strong> Measurements in Environmentally-Exposed Subjects .................. AX4-9<br />

AX4-5 Bone <strong>Lead</strong> Measurements in Occupationally-Exposed Subjects................... AX4-12<br />

AX4-6 Bone <strong>Lead</strong> Contribution to PbB..................................................................... AX4-19<br />

AX4-7 Bone <strong>Lead</strong> Studies in Pregnant and Lactating Subjects................................. AX4-22<br />

AX4-8 Bone <strong>Lead</strong> Studies <strong>of</strong> Menopausal and Middle-aged to Elderly Subjects..... AX4-30<br />

AX4-9 <strong>Lead</strong> in Deciduous Teeth from Urban and Remote Environments................ AX4-36<br />

AX4-10 <strong>Lead</strong> in Deciduous Teeth from Polluted Environments................................. AX4-38<br />

AX4-11 Summary <strong>of</strong> Selected Measurements <strong>of</strong> Urine <strong>Lead</strong> Levels in Humans ....... AX4-39<br />

AX4-12 Summary <strong>of</strong> Selected Measurements <strong>of</strong> Hair <strong>Lead</strong> Levels in Humans ......... AX4-42<br />

AX5-2.1 Effect <strong>of</strong> <strong>Lead</strong> on Erythrocyte Morphology, Mobility, and Other<br />

Miscellaneous Parameters................................................................................ AX5-2<br />

AX5-2.2 <strong>Lead</strong>, Erythrocyte Heme Enzymes, and Other Parameters.............................. AX5-6<br />

AX5-2.3 <strong>Lead</strong> Binding and Transport in Human Erythrocytes ...................................... AX5-9<br />

AX5-2.4 <strong>Lead</strong> Effects on Hematological Parameters ................................................... AX5-10<br />

AX5-2.5 <strong>Lead</strong> Interactions with Calcium Potassium in Erythrocytes .......................... AX5-12<br />

AX5-2.6 <strong>Lead</strong>, Heme, and Cytochrome P–450 ............................................................ AX5-13<br />

AX5-2.7 <strong>Lead</strong>, Erythrocyte Lipid Peroxidation, and Antioxidant Defense.................. AX5-14<br />

AX5-3.1 Summary <strong>of</strong> Key Studies on Neurochemical Alterations .............................. AX5-16<br />

AX5-3.2 Summary <strong>of</strong> Key Studies on Neurophysiological Assessments .................... AX5-20<br />

<strong>II</strong>-x<br />

Page


List <strong>of</strong> Tables<br />

(cont’d)<br />

AX5-3.3 Summary <strong>of</strong> Key Studies on Changes in Sensory Function .......................... AX5-21<br />

AX5-3.4 Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity................................ AX5-22<br />

AX5-3.5 Summary <strong>of</strong> Key Studies on Cell Morphology and Metal Disposition ......... AX5-31<br />

AX5-3.6 Key Studies Evaluating Chelation <strong>of</strong> Pb in Brain.......................................... AX5-33<br />

AX5-4.1 Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects<br />

on Offspring ................................................................................................... AX5-38<br />

AX5-4.2 Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects<br />

on Males......................................................................................................... AX5-45<br />

AX5-4.3 Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects<br />

on Females ..................................................................................................... AX5-55<br />

AX5-5.1 In Vivo and In Vitro Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on<br />

Production and Metabolism <strong>of</strong> Reactive Oxygen Species,<br />

Nitric Oxide, and Soluble Guanylate Cyclease.............................................. AX5-61<br />

AX5-5.2 Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on PKC Activity, NFkB<br />

Activation, and Apoptosis.............................................................................. AX5-66<br />

AX5-5.3 Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Blood Pressure and<br />

Adrenergic System......................................................................................... AX5-67<br />

AX5-5.4 Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Renin-angiotensin System,<br />

Kallikrein-Kinin System, Prostaglandins, Endothelin, and Atrial<br />

NatriureticPeptide (ANP)............................................................................... AX5-69<br />

AX5-5.5 Studies <strong>of</strong> Effect <strong>of</strong> <strong>Lead</strong> on Vascular Contractility ...................................... AX5-70<br />

AX5-5.6 Effects <strong>of</strong> <strong>Lead</strong> on Cultured Endothelial Cell Proliferation, Angiogenesis,<br />

and Production <strong>of</strong> Heparan Sulfate Proteoglycans and tPA .......................... AX5-71<br />

AX5-5.7 Studies <strong>of</strong> the Effect <strong>of</strong> <strong>Lead</strong> on Cultured Vascular Smooth Muscle Cells... AX5-74<br />

AX5-6.1 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Laboratory Animal Studies ....... AX5-76<br />

AX5-6.2 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Human Cell Cultures................. AX5-78<br />

<strong>II</strong>-xi<br />

Page


List <strong>of</strong> Tables<br />

(cont’d)<br />

AX5-6.3 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Carcinogenesis Animal<br />

Cell Cultures .................................................................................................. AX5-79<br />

AX5-6.4 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Laboratory<br />

Animal Studies............................................................................................... AX5-81<br />

AX5-6.5 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell<br />

Cultures Mutagenesis..................................................................................... AX5-85<br />

AX5-6.6 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell<br />

Cultures Clastogenicity.................................................................................. AX5-86<br />

AX5-6.7 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell<br />

Cultures DNA Damage .................................................................................. AX5-88<br />

AX5-6.8 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell<br />

Cultures Mutagenicity.................................................................................... AX5-90<br />

AX5-6.9 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell<br />

Cultures Clastogenicity.................................................................................. AX5-92<br />

AX5-6.10 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell<br />

Cultures DNA Damage .................................................................................. AX5-95<br />

AX5-6.11 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Non-mammalian<br />

Cultures .......................................................................................................... AX5-97<br />

AX5-6.12 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity as it Pertains<br />

to Potential Developmental Effects ............................................................... AX5-98<br />

AX5-6.13 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity as it Pertains<br />

to Potential Developmental Effects—Children ............................................. AX5-99<br />

AX5-6.14 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture<br />

Interactions—Animal................................................................................... AX5-100<br />

AX5-6.15 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture<br />

Interactions—Human ................................................................................... AX5-101<br />

AX5-6.16 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture<br />

Interactions—DNA Repair—Human........................................................... AX5-102<br />

<strong>II</strong>-xii<br />

Page


List <strong>of</strong> Tables<br />

(cont’d)<br />

AX5-6.17 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture<br />

Interactions—DNA Repair—Animal .......................................................... AX5-103<br />

AX5-6.18 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis—Animal ............. AX5-104<br />

AX5-6.19 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis Human and<br />

Animal Cell Culture Studies ........................................................................ AX5-107<br />

AX5-6.20 Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis Other ................... AX5-110<br />

AX5-7.1 Light Microscopic, Ultrastructural, and Functional Changes...................... AX5-112<br />

AX5-7.2 <strong>Lead</strong> and Free Radicals................................................................................ AX5-114<br />

AX5-7.3 Chelation with DMSA ................................................................................. AX5-117<br />

AX5-7.4 Effect <strong>of</strong> Chelator Combinations ................................................................. AX5-118<br />

AX5-7.5 Effect <strong>of</strong> Other Metals on <strong>Lead</strong> ................................................................... AX5-119<br />

AX5-8.1 Bone Growth in <strong>Lead</strong>-exposed Animals...................................................... AX5-122<br />

AX5-8.2 Regulation <strong>of</strong> Bone Cell Function in Animals—Systemic Effects<br />

<strong>of</strong> <strong>Lead</strong> ......................................................................................................... AX5-126<br />

AX5-8.3 Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong> ................................... AX5-129<br />

AX5-8.4 Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic<br />

Conditions .................................................................................................... AX5-136<br />

AX5-8.5 Uptake <strong>of</strong> <strong>Lead</strong> by Teeth.............................................................................. AX5-142<br />

AX5-8.6 Effects <strong>of</strong> <strong>Lead</strong> on Enamel and Dentin Formation ...................................... AX5-143<br />

AX5-8.7 Effects <strong>of</strong> <strong>Lead</strong> on Dental Pulp Cells........................................................... AX5-144<br />

AX5-8.8 Effects <strong>of</strong> <strong>Lead</strong> on Teeth—Dental Caries .................................................... AX5-145<br />

AX5-9.1 Studies on <strong>Lead</strong> Exposure and Immune Effects in Humans........................ AX5-147<br />

AX5-9.2 Effect <strong>of</strong> <strong>Lead</strong> on Antibody Forming Cells (In Vitro Stimulation) ............. AX5-150<br />

<strong>II</strong>-xiii<br />

Page


List <strong>of</strong> Tables<br />

(cont’d)<br />

AX5-9.3 Studies Reporting <strong>Lead</strong>-induced Suppression <strong>of</strong> Delayed Type<br />

Hypersensitivity and Related Responses ..................................................... AX5-151<br />

AX5-9.4 Effect <strong>of</strong> <strong>Lead</strong> on Allogeneic and Syngeneic Mixed Lymphocyte<br />

Responses..................................................................................................... AX5-152<br />

AX5-9.5 Effect <strong>of</strong> <strong>Lead</strong> on Mitogen-induced Lymphoid Proliferation ...................... AX5-153<br />

AX5.9.6 Pattern <strong>of</strong> <strong>Lead</strong>-induced Macrophage Immunotoxicity ............................... AX5-155<br />

AX5-10.1 Hepatic Drug Metabolism............................................................................ AX5-157<br />

AX5-10.2 Biochemical and Molecular Perturbations in <strong>Lead</strong>-induced<br />

Liver Tissue ................................................................................................. AX5-162<br />

AX5-10.3 Effect <strong>of</strong> <strong>Lead</strong> Exposure on Hepatic Cholesterol Metabolism .................... AX5-165<br />

AX5-10.4 <strong>Lead</strong>, Oxidative Stress, and Chelation Therapy........................................... AX5-166<br />

AX5-10.5 <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular<br />

Mechanisms ................................................................................................. AX5-171<br />

AX5-10.6 Effect <strong>of</strong> <strong>Lead</strong> Exposure on Liver Heme Synthesis..................................... AX5-177<br />

AX5-10.7 <strong>Lead</strong> and In Vitro Cytotoxicity in Intestinal Cells....................................... AX5-180<br />

AX5-10.8 <strong>Lead</strong> and Intestinal Uptake—Effect on Ultrastructure, Motility,<br />

Transport, and Miscellaneous ...................................................................... AX5-181<br />

AX5-10.9 <strong>Lead</strong>, Calcium, and Vitamin D Interactions, and Intestinal Enzymes ......... AX5-184<br />

AX5-11.1 <strong>Lead</strong>-binding Proteins.................................................................................. AX5-187<br />

<strong>II</strong>-xiv<br />

Page


Authors, Contributors, and Reviewers<br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS)<br />

Chapter Managers/Editors<br />

Dr. James Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principal Authors<br />

Dr. Brian Gulson—Graduate School <strong>of</strong> the Environment, Macquarie University<br />

Sydney, NSW 2109, Australia<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS<br />

AND LABORATORY ANIMALS)<br />

Chapter Managers/Editors<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principal Authors<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Sections 5-2, 5-10)<br />

<strong>II</strong>-xxi


Principal Authors<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Stephen Lasley—Dept. <strong>of</strong> Biomedical and Therapeutic Sciences, Univ. <strong>of</strong> Illinois College <strong>of</strong><br />

Medicine, PO Box 1649, Peoria, IL 61656 (Section 5.3)<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Section 5.3)<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001<br />

(Section 5.4)<br />

Dr. N.D. Vaziri—Division <strong>of</strong> Nephrology and Hypertension, University <strong>of</strong> Cali<strong>for</strong>nia – Irvine<br />

Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868 (Section 5.5)<br />

Dr. John Pierce Wise, Sr.—Maine Center <strong>for</strong> Toxicology and Environmental Health,<br />

Department <strong>of</strong> Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME<br />

04104-9300 (Section 5.6)<br />

Dr. Harvey C. Gonick—David Geffen School <strong>of</strong> Medicine, University <strong>of</strong> Cali<strong>for</strong>nia at<br />

Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049 (Sections 5.7, 5.11)<br />

Dr. Gene E. Watson—University <strong>of</strong> Rochester Medical Center, Box 705, Rochester, NY 14642<br />

(Section 5.8)<br />

Dr. Rodney Dietert—Institute <strong>for</strong> Comparative and Environmental Toxicology, College <strong>of</strong><br />

Veterinary Medicine, Cornell University, Ithaca, NY 14853 (Section 5.9)<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David A. Lawrence—Dept <strong>of</strong> Environmental and Clinical Immunology, Empire State Plaza<br />

P.O. Box 509, Albany, NY 12201<br />

<strong>II</strong>-xxii


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Michael J. McCabe, Jr.—Dept <strong>of</strong> Environmental Medicine, University <strong>of</strong> Rochester,<br />

575 Elmwood Avenue, Rochester, NY 14642<br />

Dr. Theodore I. Lidsky—New York State Institute <strong>for</strong> Basic Research, 1050 Forest RD,<br />

Staten Island, NY 10314<br />

Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001<br />

Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD<br />

EXPOSURE EFFECTS)<br />

Chapter Managers/Editors<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xxiii


Principal Authors<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. David Bellinger—Children’s Hospital, Farley Basement, Box 127, 300 Longwood Avenue,<br />

Boston, MA 02115 (Section 6.10)<br />

Dr. Margit Bleecker—Center <strong>for</strong> Occupational and Environmental Neurology, 2 Hamill Road,<br />

Suite 225, Baltimore, MD 21210 (Section 6.3)<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.<br />

Akron, NY 14001 (Section 6.8, 6.9)<br />

Dr. Kim Dietrich—University <strong>of</strong> Cincinnati College <strong>of</strong> Medicine, 3223 Eden Avenue,<br />

Kettering Laboratory, Room G31, Cincinnati, OH 45267 (Section 6.2)<br />

Dr. Pam Factor-Litvak—Columbia University Mailman School <strong>of</strong> Public Health, 722 West<br />

168th Street, Room 1614, New York, NY 10032 (Section 6.6)<br />

Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713 (Section 6.10)<br />

Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Mérida, Yucatán, México & National Institute<br />

<strong>of</strong> Public Health, Cuernavaca, Morelos, Mexico (Section 6.5)<br />

Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School <strong>of</strong> Public Health<br />

& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112<br />

(Section 6.7)<br />

Dr. Kyle Steenland—Rollins School <strong>of</strong> Public Health, Emory University, 1518 Clifton Road,<br />

Room 268, Atlanta, GA 30322 (Section 6.7)<br />

Dr. Virginia Weaver—Johns Hopkins Bloomberg School <strong>of</strong> Public Health, 615 North Wolfe<br />

Street, Room 7041, Baltimore, MD 21205 (Section 6.4)<br />

Contributors and Reviewers<br />

Dr. J. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Kazuhiko Ito—Nelson Institute <strong>of</strong> Environmental Medicine, New York University School <strong>of</strong><br />

Medicine, Tuxedo, NY 10987<br />

<strong>II</strong>-xxiv


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Kathryn Mahaffey—Office <strong>of</strong> Prevention, Pesticides and Toxic Substances,<br />

U.S. Environmental Protection Agency, Washington, DC 20460<br />

Dr. Karen Martin—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Chapter Manager/Editor<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principle Authors<br />

Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,<br />

Ontario, L5N 3C9 Canada (Section 7.1)<br />

Dr. James Kaste—Department <strong>of</strong> Earth Sciences, Dartmouth College, 352 Main Street, Hanover,<br />

NH 03755 (Section 7.1)<br />

Dr. John Drexler—Department <strong>of</strong> Geological Sciences, University <strong>of</strong> Colorado, 1216 Gillespie<br />

Drive, Boulder, CO 80305 (Section 7.1)<br />

Dr. Chris Johnson—Department <strong>of</strong> Civil and Environmental Engineering, Syracuse University,<br />

365 Link Hall, Syracuse, NY 13244 (Section 7.1)<br />

Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321<br />

(Section 7.2)<br />

<strong>II</strong>-xxv


Principle Authors<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Dwayne Moore—Cantox Environmental, Inc., 1550A Laperriere Avenue, Suite 103,<br />

Ottawa, Ontario, K1Z 7T2 Canada (Section 7.2)<br />

Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004<br />

(Section 7.2)<br />

Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,<br />

Winchester, MA 01890 (Section 7.3)<br />

Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite<br />

202, Winchester, MA 01890 (Section 7.3)<br />

Contributors and Reviewers<br />

Dr. Jerome Nriagu—Department <strong>of</strong> Environmental Health Sciences, 109 South Observatory,<br />

University <strong>of</strong> Michigan, Ann Arbor, MI 48109<br />

Dr. Judith Weis—Department <strong>of</strong> Biology, Rutgers University, Newark, NJ 07102<br />

Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Ginger Tennant—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Gail Lacey—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental Protection<br />

Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xxvi


Executive Direction<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

Dr. Lester D. Grant (Director)—National Center <strong>for</strong> Environmental Assessment-RTP Division,<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Scientific Staff<br />

Dr. Lori White (<strong>Lead</strong> Team <strong>Lead</strong>er)—National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. James S. Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Robert Elias—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Dr. Brooke Hemming—National Center <strong>for</strong> Environmental Assessment (B243-01), U.S.<br />

Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Anuradha Muldipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Mary Ross— National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xxvii


Technical Support Staff<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(cont’d)<br />

Mr. Douglas B. Fennell—Technical In<strong>for</strong>mation Specialist, National Center <strong>for</strong> Environmental<br />

Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC<br />

27711 (Retired)<br />

Ms. Emily R. Lee—Management Analyst, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Diane H. Ray—Program Specialist, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Donna Wicker—Administrative Officer, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Mr. Richard Wilson—Clerk, National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Document Production Staff<br />

Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Mr. John A. Bennett—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,<br />

Suite 1450, McLean, VA 22102<br />

Ms. Sandra L. Hughey—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards<br />

Mill Road, Suite 201, Raleigh, NC 27607<br />

Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

<strong>II</strong>-xxviii


Chair<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,<br />

Albuquerque, NM<br />

Members<br />

Dr. Joshua Cohen—Faculty, Center <strong>for</strong> the Evaluation <strong>of</strong> Value and Risk, Institute <strong>for</strong> Clinical<br />

Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA<br />

Dr. Deborah Cory-Slechta—Director, University <strong>of</strong> Medicine and Dentistry <strong>of</strong> New Jersey and<br />

Rutgers State University, Piscataway, NJ<br />

Dr. Ellis Cowling*—University Distinguished Pr<strong>of</strong>essor-at-Large, North Carolina State<br />

University, Colleges <strong>of</strong> Natural Resources and Agriculture and Life Sciences, North Carolina<br />

State University, Raleigh, NC<br />

Dr. James D. Crapo [M.D.]*—Pr<strong>of</strong>essor, Department <strong>of</strong> Medicine, National Jewish Medical and<br />

Research Center, Denver, CO<br />

Dr. Bruce Fowler—Assistant Director <strong>for</strong> Science, Division <strong>of</strong> Toxicology and Environmental<br />

Medicine, Office <strong>of</strong> the Director, Agency <strong>for</strong> Toxic Substances and Disease Registry, U.S.<br />

Centers <strong>for</strong> Disease Control and Prevention (ATSDR/CDC), Chamblee, GA<br />

Dr. Andrew Friedland—Pr<strong>of</strong>essor and Chair, Environmental Studies Program, Dartmouth<br />

College, Hanover, NH<br />

Dr. Robert Goyer [M.D.]—Emeritus Pr<strong>of</strong>essor <strong>of</strong> Pathology, Faculty <strong>of</strong> Medicine, University <strong>of</strong><br />

Western Ontario (Canada), Chapel Hill, NC<br />

Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO<br />

Dr. Bruce Lanphear [M.D.]—Sloan Pr<strong>of</strong>essor <strong>of</strong> Children’s Environmental Health, and the<br />

Director <strong>of</strong> the Cincinnati Children’s Environmental Health Center at Cincinnati Children’s<br />

Hospital Medical Center and the University <strong>of</strong> Cincinnati, Cincinnati, OH<br />

Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (<strong>US</strong>GS),<br />

Menlo Park, CA<br />

<strong>II</strong>-xxix


Members<br />

(cont’d)<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

(cont’d)<br />

Dr. Frederick J. Miller*—Consultant, Cary, NC<br />

Dr. Paul Mushak—Principal, PB Associates, and Visiting Pr<strong>of</strong>essor, Albert Einstein College <strong>of</strong><br />

Medicine (New York, NY), Durham, NC<br />

Dr. Michael Newman—Pr<strong>of</strong>essor <strong>of</strong> Marine Science, School <strong>of</strong> Marine Sciences, Virginia<br />

Institute <strong>of</strong> Marine Science, College <strong>of</strong> William & Mary, Gloucester Point, VA<br />

Mr. Richard L. Poirot*—Environmental Analyst, <strong>Air</strong> Pollution Control Division, Department <strong>of</strong><br />

Environmental Conservation, Vermont Agency <strong>of</strong> Natural Resources, Waterbury, VT<br />

Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA<br />

Dr. Joel Schwartz—Pr<strong>of</strong>essor, Environmental Health, Harvard University School <strong>of</strong> Public<br />

Health, Boston, MA<br />

Dr. Frank Speizer [M.D.]*—Edward Kass Pr<strong>of</strong>essor <strong>of</strong> Medicine, Channing Laboratory, Harvard<br />

Medical School, Boston, MA<br />

Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,<br />

Moscow, ID<br />

Dr. Barbara Zielinska*—Research Pr<strong>of</strong>essor, Division <strong>of</strong> Atmospheric Science, Desert Research<br />

Institute, Reno, NV<br />

SCIENCE ADVISORY BOARD STAFF<br />

Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,<br />

Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)<br />

(Physical/Courier/FedEx Address: Fred A. Butterfield, <strong>II</strong>I, <strong>EPA</strong> Science Advisory Board Staff<br />

Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,<br />

DC 20004, Telephone: 202-343-9994)<br />

*Members <strong>of</strong> the statutory Clean <strong>Air</strong> Scientific Advisory Committee (CASAC) appointed by the<br />

U.S. <strong>EPA</strong> Administrator<br />

<strong>II</strong>-xxx


Abbreviations and Acronyms<br />

αFGF α-fibroblast growth factor<br />

AA arachidonic acid<br />

AAL active avoidance learning<br />

AAS atomic absorption spectroscopy<br />

ABA β-aminoisobutyric acid<br />

ACBP Achenbach Child Behavior Pr<strong>of</strong>ile<br />

ACE angiotensin converting enzyme<br />

ACh acetylcholine<br />

AChE acetylcholinesterase<br />

ACR acute-chronic ratio<br />

AD adult<br />

ADC analog digital converter<br />

ADP adenosine diphosphate<br />

AE anion exchange<br />

AEA N-arachidonylethanolamine<br />

AFC antibody <strong>for</strong>ming cells<br />

2-AG 2-arachidonylglycerol<br />

A horizon uppermost layer <strong>of</strong> soil (litter and humus)<br />

AHR aryl hydrocarbon receptor<br />

AI angiotensin I<br />

ALA *-aminolevulinic acid<br />

ALAD *-aminolevulinic acid dehydratase<br />

ALAS aminolevulinic acid synthetase<br />

ALAU urinary δ-aminolevulinic acid<br />

ALD aldosterone<br />

ALS amyotrophic lateral sclerosis<br />

ALT alanine aminotransferase<br />

ALWT albumin weight<br />

AMEM Alpha Minimal Essential Medium<br />

AMP adenosine monophosphate<br />

ANCOVA analysis <strong>of</strong> covariance<br />

ANF atrial natriuretic factor<br />

Ang <strong>II</strong> angiotensin <strong>II</strong><br />

ANOVA analysis <strong>of</strong> variance<br />

<strong>II</strong>-xxxi


ANP atrial natriuretic peptide<br />

AP alkaline phosphatase<br />

AP-1 activated protein-1<br />

ApoE apolipoprotein E<br />

AQCD <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> Document<br />

Arg arginine<br />

AS52 cells derived from the CHO cell line<br />

ASGP-R aceyl glycoprotein receptor<br />

AST aspartate aminotransferase<br />

ASV anode stripping voltammetry<br />

3-AT 3-aminotriazole; 3-amino triazide<br />

ATP adenosine triphosphate<br />

ATP1A2 sodium-potassium adenosine triphosphase α2<br />

ATPase adenosine triphosphatase<br />

ATSDR Agency <strong>for</strong> Toxic Substances and Disease Research<br />

AVCD atrioventricular conduction deficit<br />

AVS acid volatile sulfide<br />

AWQC ambient water quality criteria<br />

$ beta-coefficient; slope <strong>of</strong> an equation<br />

$FGF $-fibroblast growth factor<br />

17$–HS 17$-hydroxysteriod<br />

3$-HSD 3$-hydroxysteriod dehydrogenase<br />

17$-HSDH 17$-hydroxysteriod dehydrogenase<br />

6$-OH-cortisol 6-$-hydroxycortisol<br />

B both<br />

BAEP brainstem auditory-evoked potentials<br />

BAER brainstem auditory-evoked responses<br />

BAF bioaccumulation factor<br />

B cell B lymphocyte<br />

BCFs bioconcentration factors<br />

BCS bovine calf serum<br />

BDNF brain derived neurotrophic factor<br />

BDWT body weight changes<br />

BEI biological exposure index<br />

BFU-E blood erythroid progenitor<br />

<strong>II</strong>-xxxii


BLL blood lead level<br />

BLM biotic ligand model<br />

BM basement membrane<br />

BMI body mass index<br />

BDNF brain-derived neurotrophic factor<br />

BOTMP Bruinicks-Oseretsky Test <strong>of</strong> Motor Pr<strong>of</strong>iciency<br />

BP blood pressure<br />

BPb blood lead concentration<br />

BSA bovine serum albumin<br />

BSI Brief Symptom Inventory<br />

BTQ Boston Teacher Questionnaire<br />

BUN blood urea nitrogen<br />

bw, b. wt., BW body weight<br />

C3H10T/12 mouse embryo cell line<br />

C3, C4 complement proteins<br />

CA chromosome aberration<br />

CA3 cornu ammonis 3 region <strong>of</strong> hippocampus<br />

45 Ca calcium-45 radionuclide<br />

Ca-ATP calcium-dependent adenosine triphosphate<br />

Ca-ATPase calcium-dependent adenosine triphosphatase<br />

CaCO3<br />

calcium carbonate<br />

CaEDTA calcium disodium ethylenediaminetetraacetic acid<br />

CAL calcitonin<br />

CaM calmodulin<br />

Ca-Mg-ATPase calcium-magnesium-dependent adenosine triphosphatase<br />

cAMP cyclic adenosinemonophosphate<br />

CaNa2 EDTA calcium disodium ethylenediaminetetraacetic acid<br />

CANTAB Cambridge Neuropsychological Testing Automated Battery<br />

CAT catalase; Cognitive Abilities Test<br />

CBCL Achenbach Child Behavior Checklist<br />

CBCL-T Total Behavior Problem Score<br />

CBL cumulative blood lead<br />

CBLI cumulative blood lead index<br />

CCB cytochalasin B<br />

CCD charge-coupled device<br />

<strong>II</strong>-xxxiii


CCE Coordination Center <strong>for</strong> Effects<br />

CCL carbon tetrachloride<br />

CCS cosmic calf serum<br />

C-CVRSA<br />

Cd cadmium<br />

coefficient <strong>of</strong> component variance <strong>of</strong> respiratory sinus<br />

arrhythmia<br />

109 Cd cadmium-109 radionuclide<br />

CdU urinary cadmium<br />

CEC cation exchange capacity<br />

CESD, CES-D Center <strong>for</strong> Epidemiologic Studies Depression (scale)<br />

GFAP glial fibrillary acidic protein<br />

CFU-E colony <strong>for</strong>ming unit blood-erythroid progenitor (cell count)<br />

CFU-GEMM colony <strong>for</strong>ming unit blood-pluripotent progenitor (cell count)<br />

CFU-GM blood granulocyte/macrophage progenitor (cell count)<br />

cGMP cyclic guanosine-3',5'-monophosphate<br />

ChAT choline acetyltransferase<br />

CHD coronary heart disease<br />

CHO Chinese hamster ovary cell line<br />

CI confidence interval<br />

CLE-SV competitive ligand-exchange/stripping voltammetry<br />

CLRTAP Convention on Long-Range Transboundary <strong>of</strong> <strong>Air</strong> Pollution<br />

CLS Cincinnati <strong>Lead</strong> Study<br />

CMC criterion maximum concentration<br />

CMI cell-mediated immunity<br />

CNS central nervous system<br />

COH cation-osmotic hemolysis<br />

ConA concanavalin A<br />

COR cortisol<br />

CoTx cotreatment<br />

COX-2 cyclooxygenase-2<br />

CP coproporphryn<br />

CPT current perception threshold<br />

cr creatinine<br />

CRAC calcium release activated calcium reflux<br />

CREB cyclic AMP-response element binding protein<br />

CRF chronic renal failure<br />

<strong>II</strong>-xxxiv


CRI chronic renal insufficiency<br />

CSF cerebrospinal fluid<br />

CuZn-SOD copper and zinc-dependent superoxide dismutase<br />

CV<br />

conduction velocity<br />

CVLT Cali<strong>for</strong>nia Verbal Learning Test<br />

CVR-R<br />

coefficient <strong>of</strong> variation <strong>of</strong> the R-R interval<br />

CYP cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)<br />

CYP3a11 cytochrome P450 3a11<br />

D D-statistic<br />

DA dopamine; dopaminergic<br />

dbcAMP dibutyryl cyclic adenosine-3',5'-monophosphate<br />

DCV distribution <strong>of</strong> conduction velocities<br />

DEAE diethylaminoethyl (chromatography)<br />

DET diffusive equilibrium thin films<br />

DEYO death <strong>of</strong> young<br />

DFS decayed or filled surfaces, permanent teeth<br />

dfs covariate-adjusted number <strong>of</strong> caries<br />

DG dentate gyrus<br />

DGT diffusive gradient thin films<br />

DL DL-statistic<br />

DMEM Dulbecco’s Minimal Essential Medium<br />

DMEM/F12 Dulbecco’s Minimal Essential Medium/Ham’s F12<br />

DMFS decayed, missing, or filled surfaces, permanent teeth<br />

DMPS 2,3-dimercaptopropane 1-sulfonate<br />

DMSA 2,3-dimercaptosuccinic acid<br />

DMT Donnan membrane technique<br />

DMTU dimethylthiourea<br />

DNA deoxyribonucleic acid<br />

DO distraction osteogenesis<br />

DOC dissolved organic carbon<br />

DOM dissolved organic carbon<br />

DOPAc 3,4-dihydroxyphenylacetic acid<br />

DPASV differential pulse anodic stripping voltammetry<br />

dp/dt rate <strong>of</strong> left ventricular isovolumetric pressure<br />

DPPD N-N-diphenyl-p-phynylene-diamine<br />

<strong>II</strong>-xxxv


DR drinking water<br />

DSA delayed spatial alternation<br />

DTC diethyl dithiocarbomate complex<br />

DTH delayed type hypersensitivity<br />

DTPA diethylenetriaminepentaacetic acid<br />

DTT dithiothreitol<br />

dw dry weight<br />

E embryonic day<br />

E2<br />

estradiol<br />

EBE early biological effect<br />

EBV Epstein-Barr virus<br />

EC European Community<br />

EC50<br />

effect concentration <strong>for</strong> 50% <strong>of</strong> test population<br />

eCB endocannabinoid<br />

ECG electrocardiogram<br />

Eco-SSL ecological soil screening level<br />

EDS energy dispersive spectrometers<br />

EDTA ethylenediaminetetraacetic acid<br />

EEDQ N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone<br />

EEG electroencephalogram<br />

EG egg<br />

EGF epidermal growth factor<br />

EGG effects on eggs<br />

EGPN egg production<br />

EKG electrocardiogram<br />

electro electrophysiological stimulation<br />

EM/CM experimental medium-to-control medium (ratio)<br />

EMEM Eagle’s Minimal Essential Medium<br />

eNOS endothelial nitric oxide synthase<br />

EP erythrocyte protoporphyrin<br />

<strong>EPA</strong> U.S. Environmental Protection Agency<br />

Epi epinephrine<br />

EPMA electron probe microanalysis<br />

EPO erythropoietin<br />

EPSC excitatory postsynaptic currents<br />

<strong>II</strong>-xxxvi


EPT macroinvertebrates from the Ephemeroptera (mayflies),<br />

Plecoptera (stoneflies), and Trichoptera (caddisflies) group<br />

ERG electroretinogram; electroretinographic<br />

ERL effects range – low<br />

ERM effects range – median<br />

EROD ethoxyresorufin-O-deethylase<br />

ESCA electron spectroscopy <strong>for</strong> chemical analysis<br />

ESRD end-stage renal disease<br />

EST estradiol<br />

ESTH eggshell thinning<br />

ET endothelein; essential tremor<br />

ETOH ethyl alcohol<br />

EXAFS extended X-ray absorption fine structure<br />

EXANES extended X-ray absorption near edge spectroscopy<br />

F F-statistic<br />

F344 Fischer 344 (rat)<br />

FAV final acute value<br />

FBS fetal bovine serum<br />

FCS fetal calf serum<br />

FCV final chronic value<br />

FD food<br />

FEF <strong>for</strong>ced expiratory flow<br />

FEP free erythrocyte protoporphyrin<br />

FERT fertility<br />

FEV1<br />

<strong>for</strong>ced expiratory volume in one second<br />

FGF fibroblast growth factor (e.g., βFGF, αFGF)<br />

FI fixed interval (operant conditioning)<br />

FIAM free ion activity model<br />

FMLP N-<strong>for</strong>myl-L-methionyl-L-leucyl-L-phenylalanine<br />

fMRI functional magnetic resonance imaging<br />

FR fixed-ratio operant conditioning<br />

FSH follicle stimulating hormone<br />

FT3 free triiodothyronine<br />

FT4 free thyroxine<br />

FTES free testosterone<br />

<strong>II</strong>-xxxvii


FT<strong>II</strong> Fagan Test <strong>of</strong> Infant Intelligence<br />

FTPLM flow-through permeation liquid membranes<br />

FURA-2 1-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benz<strong>of</strong>uranyloxy]-2-<br />

(2-amino-5-methylphenoxy) ethane-N,N,N',N'-tetraacetic acid<br />

FVC <strong>for</strong>ced vital capacity<br />

(-GT (-glutamyl transferase<br />

G gestational day<br />

GABA gamma aminobutyric acid<br />

GAG glycosaminoglycan<br />

G12 CHV79 cells derived from the V79 cell line<br />

GCI General Cognitive Index<br />

GD gestational day<br />

GDP guanosine diphosphate<br />

GEE generalized estimating equations<br />

GFAAS graphite furnace atomic absorption spectroscopy<br />

GFR glomerular filtration rate<br />

GGT (-glutamyl transferase<br />

GH growth hormone<br />

GI gastrointestinal<br />

GIME-VIP gel integrated microelectrodes combined with voltammetric<br />

in situ pr<strong>of</strong>iling<br />

GIS geographic in<strong>for</strong>mation system<br />

GLU glutamate<br />

GMAV genus mean acute value<br />

GMCV genus mean chronic value<br />

GMP guanosine monophosphate<br />

GMPH general morphology<br />

GnRH gonadotropin releasing hormone<br />

GOT aspartate aminotransferase<br />

GP gross productivity<br />

G6PD, G6PDH glucose-6-phosphate dehydrogenase<br />

GPEI glutathione S-transferase P enhancer element<br />

gp91 phox NAD(P)H oxidase<br />

GPT glutamic-pyruvic transaminase<br />

GPx glutathione peroxidase<br />

GRO growth<br />

<strong>II</strong>-xxxviii


GRP78 glucose-regulated protein 78<br />

GSD geometric standard deviation<br />

GSH reduced glutathione<br />

GSIM gill surface interaction model<br />

GSSG glutathione disulfide<br />

GST glutathione-S-transferase<br />

GSTP placental glutathione transferase<br />

GTP guanosine triphosphate<br />

GV gavage<br />

H + acidity<br />

3<br />

H hydrogen-3 radionuclide (tritium)<br />

HA humic acid; hydroxyapatite<br />

Hb hemoglobin<br />

HBEF Hubbard Brook Experimenatl Forest<br />

HBSS Hank’s Balanced Salt Solution<br />

HCG; hCG human chorionic gonadotropin<br />

Hct hematocrit<br />

HDL high-density lipoprotein (cholesterol)<br />

HEP habitat evaluation procedure<br />

HET Binghamton heterogeneous stock<br />

HFPLM hollow fiber permeation liquid membranes<br />

Hgb hemoglobin<br />

HGF hepatocyte growth factor<br />

HH hydroxylamine hydrochloride<br />

H-H high-high<br />

HHANES Hispanic Health and Nutrition Examination Survey<br />

H-L high-low<br />

HLA human leukocyte antigen<br />

H-MEM minimum essential medium/nutrient mixture–F12-Ham<br />

HMP hexose monophosphate shunt pathway<br />

HNO3<br />

nitric acid<br />

H2O2<br />

hydrogen peroxide<br />

HOME Home Observation <strong>for</strong> Measurement <strong>of</strong> Environment<br />

HOS TE human osteosarcoma cells<br />

HPLC high-pressure liquid chromatography<br />

<strong>II</strong>-xxxix


H3PO4<br />

phosphoric acid<br />

HPRT hypoxanthine phosphoribosyltransferase (gene)<br />

HR heart rate<br />

HSI habitat suitability indices<br />

H2SO4<br />

sulfuric acid<br />

HSPG heparan sulfate proteoglycan<br />

Ht hematocrit<br />

HTC hepatoma cells<br />

hTERT catalytic subunit <strong>of</strong> human telomerase<br />

HTN hypertension<br />

IBL integrated blood lead index<br />

IBL H WRAT-R integrated blood lead index H Wide Range Achievement<br />

Test-Revised (interaction)<br />

ICD International Classification <strong>of</strong> Diseases<br />

ICP inductively coupled plasma<br />

ICP-AES inductively coupled plasma atomic emission spectroscopy<br />

ICP-MS, ICPMS inductively coupled plasma mass spectrometry<br />

ID-MS isotope dilution mass spectrometry<br />

IFN interferon (e.g., IFN-()<br />

Ig immunoglobulin (e.g., IgA, IgE, IgG, IgM)<br />

IGF-1 insulin-like growth factor 1<br />

IL interleukin (e.g., IL-1, IL-1$, IL-4, IL-6, IL-12)<br />

ILL incipient lethal level<br />

immuno immunohistochemical staining<br />

IMP inosine monophosphate<br />

iNOS inducible nitric oxide synthase<br />

i.p., IP intraperitoneal<br />

IPSC inhibitory postsynaptic currents<br />

IQ intelligence quotient<br />

IRT interresponse time<br />

ISEL in situ end labeling<br />

ISI interstimulus interval<br />

i.v., IV intravenous<br />

IVCD intraventricular conduction deficit<br />

JV juvenile<br />

<strong>II</strong>-xl


KABC Kaufman Assessment Battery <strong>for</strong> Children<br />

KTEA Kaufman Test <strong>of</strong> Educational Achievement<br />

KXRF, K-XRF K-shell X-ray fluorescence<br />

LA lipoic acid<br />

LB laying bird<br />

LC lactation<br />

LC50<br />

lethal concentration at which 50% <strong>of</strong> exposed animals die<br />

LC74<br />

lethal concentration at which 74% <strong>of</strong> exposed animals die<br />

LD50<br />

lethal dose at which 50% <strong>of</strong> exposed animals die<br />

LDH lactate dehydrogenase<br />

LDL low-density lipoprotein (cholesterol)<br />

L-dopa 3,4-dihydroxyphenylalanine (precursor <strong>of</strong> dopamine)<br />

LE Long Evans (rat)<br />

LET linear energy transfer (radiation)<br />

LH luteinizing hormone<br />

LHRH luteinizing hormone releasing hormone<br />

LN lead nitrate<br />

L-NAME L-N G -nitroarginine methyl ester<br />

LOAEL lowest-observed adverse effect level<br />

LOEC lowest-observed-effect concentration<br />

LOWESS locally weighted scatter plot smoother<br />

LPO lipoperoxide<br />

LPP lipid peroxidation potential<br />

LPS lipopolysaccharide<br />

LT leukotriene<br />

LT50<br />

time to kill 50%<br />

LTER Long-Term Ecological Research (sites)<br />

LTP long term potentiation<br />

LVH left ventricular hypertrophy<br />

µPIXE micr<strong>of</strong>ocused particle induced X-ray emission<br />

µSXRF micr<strong>of</strong>ocused synchrotron-based X-ray fluorescence<br />

MA mature<br />

MA-10 mouse Leydig tumor cell line<br />

MANCOVA multivariate analysis <strong>of</strong> covariance<br />

MAO monoamine oxidase<br />

<strong>II</strong>-xli


MATC maximum acceptable threshold concentration<br />

MDA malondialdehyde<br />

MDA-TBA malondialdehyde-thiobarbituric acid<br />

MDCK kidney epithelial cell line<br />

MDI Mental Development Index (score)<br />

MDRD Modification <strong>of</strong> Diet in Renal Disease (study)<br />

MEM Minimal Essential Medium<br />

MG microglobulin<br />

Mg-ATPase magnesium-dependent adenosine triphosphatase<br />

MiADMSA monoisamyl dimercaptosuccinic acid<br />

Mi-DMSA mi monoisoamyl dimercaptosuccinic acid<br />

MK-801 NMDA receptor antagonist<br />

MLR mixed lymphocyte response<br />

MMSE Mini-Mental State Examination<br />

MMTV murine mammary tumor virus<br />

MN micronuclei <strong>for</strong>mation<br />

MND motor neuron disease<br />

MNNG N-methyl-N'-nitro-N-nitrosoguanidine<br />

MPH morphology<br />

MRI magnetic resonance imaging<br />

mRNA messenger ribonucleic acid<br />

MROD methoxyresorufin-O-demethylase<br />

MRS magnetic resonance spectroscopy<br />

MS mass spectrometry<br />

MSCA McCarthy Scales <strong>of</strong> Children’s Abiltities<br />

mSQGQs mean sediment quality guideline quotients<br />

MT metallothionein<br />

MVV maximum voluntary ventilation<br />

MW molecular weight (e.g., high-MW, low-MW)<br />

N, n number <strong>of</strong> observations<br />

N/A not available<br />

NAAQS National Ambient <strong>Air</strong> <strong>Quality</strong> Standards<br />

NAC N-acetyl cysteine<br />

NAD nicotinamide adenine dinucleotide<br />

NADH reduced nicotinamide adenine dinucleotide<br />

<strong>II</strong>-xlii


NADP nicotinamide adenine dinucleotide phosphate<br />

NAD(P)H, NADPH reduced nicotinamide adenine dinucleotide phosphate<br />

NADS nicotinamide adenine dinucleotide synthase<br />

NAF nafenopin<br />

NAG N-acetyl-$-D-glucosaminidase<br />

Na-K-ATPase sodium-potassium-dependent adenosine triphosphatase<br />

NAWQA National Water-<strong>Quality</strong> Assessment<br />

NBT nitro blue tetrazolium<br />

NCBP National Contaminant Biomonitoring Program<br />

NCD nuclear chromatin decondensation (rate)<br />

NCS newborn calf serum<br />

NCTB Neurobehavioral Core Test Battery<br />

NCV nerve conduction velocity<br />

ND non-detectable; not detected<br />

NDI nuclear divison index<br />

NE norepinephrine<br />

NES Neurobehavioral Evaluation System<br />

NF-κB nuclear transcription factor-κB<br />

NGF nerve growth factor<br />

NHANES National Health and Nutrition Examination Survey<br />

NIOSH National Institute <strong>for</strong> Occupational Safety and Health<br />

NIST National Institute <strong>for</strong> Standards and Technology<br />

NK natural killer<br />

NMDA N-methyl-D-aspartate<br />

NMDAR N-methyl-D-aspartate receptor<br />

NMR nuclear magnetic resonance<br />

NO nitric oxide<br />

NO2<br />

nitrogen dioxide<br />

NO3<br />

nitrate<br />

NOAEC no-observed-adverse-effect concentration<br />

NOAEL no-observed-adverse-effect level<br />

NOEC no-observed-effect concentration<br />

NOEL no-observed-effect level<br />

NOM natural organic matter<br />

NORs nucleolar organizing regions<br />

<strong>II</strong>-xliii


NOS nitric oxide synthase; not otherwise specified<br />

NOx<br />

nitrogen oxides<br />

NP net productivity<br />

NPSH nonprotein sulfhydryl<br />

NR not reported<br />

NRC National Research Council<br />

NRK normal rat kidney<br />

NS nonsignificant<br />

NSAID non-steroidal anti-inflammatory agent<br />

NT neurotrophin<br />

NTA nitrilotriacetic acid<br />

O2<br />

oxygen<br />

ODVP <strong>of</strong>fspring development<br />

OH hydroxyl<br />

7-OH-coumarin 7-hydroxy-coumarin<br />

1,25-(OH)2-D, 1,25-(OH)2 D3 1,25-dihydroxyvitamin D<br />

24,25-(OH)2-D3<br />

24,25-dihydroxyvitamin D<br />

25-OH-D3<br />

25-hydroxyvitamin D<br />

8-OHdG 8-hydroxy-2'-deoxyguanosine<br />

O horizon <strong>for</strong>est floor<br />

OR odds ratio; other oral<br />

OSWER Office <strong>of</strong> Solid Waste and Emergency Response<br />

P, p probability value<br />

P300 event-related potential<br />

P450 1A1 cytochrome P450 1A1<br />

P450 1A2 cytochrome P450 1A2<br />

P450 CYP3a11 cytochrome P450 3a11<br />

PAD peripheral arterial disease<br />

PAH polycyclic aromatic hydrocarbon<br />

PAI-1 plasminogen activator inhibitor-1<br />

PAR population attributable risk<br />

Pb lead<br />

203<br />

Pb lead-203 radionuclide<br />

204 206 207 208<br />

Pb, Pb, Pb, Pb stable isotopes <strong>of</strong> lead-204, -206, -207, -208, respectively<br />

210 Pb lead-210 radionuclide<br />

<strong>II</strong>-xliv


Pb(Ac)2<br />

lead acetate<br />

PbB blood lead concentration<br />

PbCl2<br />

lead chloride<br />

Pb(ClO4)2<br />

lead chlorate<br />

PBG-S porphobilinogen synthase<br />

PBMC peripheral blood mononuclear cells<br />

Pb(NO3)2<br />

lead nitrate<br />

PbO lead oxides (or litharge)<br />

PBP progressive bulbar paresis<br />

PbS galena<br />

PbU urinary lead<br />

PC12 pheochromocytoma cell<br />

PCR polymerase chain reaction<br />

PCV packed cell volume<br />

PDE phosphodiesterase<br />

PDGF platelet-derived growth factor<br />

PDI Psychomotor Development Index<br />

PEC probable effect concentration<br />

PEF expiratory peak flow<br />

PG prostaglandin (e.g., PGE2, PGF2); prostate gland<br />

PHA phytohemagglutinin A<br />

Pi inorganic phosphate<br />

PIXE particle induced X-ray emission<br />

PKC protein kinase C<br />

pl NEpi plasma norepinephrine<br />

PMA progressive muscular atrophy<br />

PMN polymorphonuclear leucocyte<br />

PMR proportionate mortality ratio<br />

PN postnatal (day)<br />

P5N pyrimidine 5'-nucleotidase<br />

PND postnatal day<br />

p.o., PO per os (oral administration)<br />

POMS Pr<strong>of</strong>ile <strong>of</strong> Mood States<br />

ppb parts per billion<br />

ppm parts per million<br />

<strong>II</strong>-xlv


PPVT-R Peabody Picture Vocabulary Test-Revised<br />

PRA plasma renin activity<br />

PRL prolactin<br />

PROG progeny counts or numbers<br />

PRR prevalence rate ratio<br />

PRWT progeny weight<br />

PST percent transferrin saturation<br />

PTH parathyroid hormone<br />

PTHrP parathyroid hormone-related protein<br />

PVC polyvinyl chloride<br />

PWM pokeweed mitogen<br />

PRWT progeny weight<br />

QA/QC quality assurance/quality control<br />

Q/V flux <strong>of</strong> air (Q) divided by volume <strong>of</strong> culture (V)<br />

r Pearson correlation coefficient<br />

R 2 multiple correlation coefficient<br />

2<br />

r correlation coefficient<br />

226<br />

Ra most stable isotope <strong>of</strong> radium<br />

R/ALAD ratio <strong>of</strong> ALAD activity be<strong>for</strong>e and after reactivation<br />

RAVLT Rey Auditory Verbal Learning Test<br />

86<br />

Rb rubidium-86 radionuclide<br />

RBA relative bioavailablity<br />

RBC red blood cell; erythrocyte<br />

RBF renal blood flow<br />

RBP retinol binding protein<br />

RBPH reproductive behavior<br />

RCPM Ravens Colored Progressive Matrices<br />

REL rat epithelial (cells)<br />

REP reproduction<br />

RHIS reproductive organ histology<br />

222<br />

Rn most stable isotope <strong>of</strong> radon<br />

RNA ribonucleic acid<br />

ROS reactive oxygen species<br />

ROS 17.2.8 rat osteosarcoma cell line<br />

RPMI 1640 Roswell Park Memorial Institute basic cell culture medium<br />

<strong>II</strong>-xlvi


RR<br />

RT<br />

RSEM<br />

RSUC<br />

RT<br />

∑SEM<br />

SA7<br />

SAB<br />

SAM<br />

SBIS-4<br />

s.c., SC<br />

SCAN<br />

SCE<br />

SCP<br />

SD<br />

SDH<br />

SDS<br />

SE<br />

SEM<br />

SES<br />

sGC<br />

SH<br />

SHBG<br />

SHE<br />

SIMS<br />

SIR<br />

SLP<br />

SM<br />

SMAV<br />

SMR<br />

SNAP<br />

SNP<br />

SO2<br />

SOD<br />

relative risk; rate ratio<br />

reaction time<br />

resorbed embryos<br />

reproductive success (general)<br />

reproductive tissue<br />

sum <strong>of</strong> the molar concentrations <strong>of</strong> simultaneously extracted<br />

metal<br />

simian adenovirus<br />

Science Advisory Board<br />

S-adenosyl-L-methionine<br />

Stan<strong>for</strong>d-Binet Intelligence Scale-4th edition<br />

subcutaneous<br />

Test <strong>for</strong> Auditory Processing Disorders<br />

selective chemical extraction; sister chromatid exchange<br />

stripping chronopotentiometry<br />

Spraque-Dawley (rat); standard deviation<br />

succinic acid dehydrogenase<br />

sodium dodecyl sulfate; Symbol Digit Substitution<br />

standard error; standard estimation<br />

standard error <strong>of</strong> the mean<br />

socioeconomic status<br />

soluble guanylate cyclase<br />

sulfhydryl<br />

sex hormone binding globulin<br />

Syrian hamster embryo cell line<br />

secondary ion mass spectrometry<br />

standardized incidence ratio<br />

synthetic leaching procedure<br />

sexually mature<br />

species mean acute value<br />

standardized mortality ratio<br />

Schneider Neonatal Assessment <strong>for</strong> Primates<br />

sodium nitroprusside<br />

sulfur dioxide<br />

superoxide dismutase<br />

<strong>II</strong>-xlvii


SOPR sperm-oocyte penetration rate<br />

SPCL sperm cell counts<br />

SPCV sperm cell viability<br />

SQGs sediment quality guidelines<br />

SRA Self Reported Antisocial Behavior scale<br />

SRD Self Report <strong>of</strong> Delinquent Behavior<br />

SRIF somatostatin<br />

SRM Standard Reference Material<br />

SRT simple reaction time<br />

SSADMF Social Security Administration Death Master File<br />

SSB single-strand breaks<br />

SSEP somatosensory-evoked potential<br />

StAR steroidogenic acute regulatory protein<br />

STORET STOrage and RETrieval<br />

SVC sensory conduction velocity<br />

SVRT simple visual reaction time<br />

T testosterone<br />

TA tail<br />

TABL time-averaged blood lead<br />

T&E threatened and endangered (species)<br />

TAT tyrosine aminotransferase<br />

TB tibia<br />

TBARS thiobarbituric acid-reactive species<br />

TBPS Total Behavior Problem Score<br />

TCDD methionine-choline-deficient diet<br />

T cell T lymphocyte<br />

TCLP toxic characteristic leaching procedure<br />

TE testes<br />

TEC threshold effect concentration<br />

TEDG testes degeneration<br />

TEL tetraethyl lead<br />

TES testosterone<br />

TEWT testes weight<br />

TF transferrin, translocation factor<br />

TG 6-thioguanine<br />

<strong>II</strong>-xlviii


TGF trans<strong>for</strong>ming growth factor<br />

TH tyrosine hydroxylase<br />

232 Th stable isotope <strong>of</strong> thorium-232<br />

TLC Treatment <strong>of</strong> <strong>Lead</strong>-exposed Children (study)<br />

TNF tumor necrosis factor (e.g., TNF-α)<br />

TOF time-<strong>of</strong>-flight<br />

tPA plasminogen activator<br />

TPRD total production<br />

TRH thyroid releasing hormone<br />

TRV toxicity reference value<br />

TSH thyroid stimulating hormone<br />

TSP triple-super phosphate<br />

TT3 total triiodothyronine<br />

TT4 serum total thyroxine<br />

TTES total testosterone<br />

TTR transthyretin<br />

TU toxic unit<br />

TWA time-weighted average<br />

TX tromboxane (e.g., TXB2)<br />

U uriniary<br />

235 238<br />

U, U uranium-234 and -238 radionuclides<br />

UCP urinary coproporphyrin<br />

UDP uridine diphosphate<br />

UNECE United Nations Economic Commission <strong>for</strong> Europe<br />

Ur urinary<br />

<strong>US</strong>FWS U.S. Fish and Wildlife Service<br />

<strong>US</strong>GS United States Geological Survey<br />

UV ultraviolet<br />

V79 Chinese hamster lung cell line<br />

VA Veterans Administration<br />

VC vital capacity; vitamin C<br />

VDR vitamin D receptor<br />

VE vitamin E<br />

VEP visual-evoked potential<br />

VI<br />

variable-interval<br />

<strong>II</strong>-xlix


vit C vitamin C<br />

vit E vitamin E<br />

VMA vanilmandelic acid<br />

VMI Visual-Motor Integration<br />

VSM vascular smooth muscle (cells)<br />

VSMC vascular smooth muscle cells<br />

WAIS Wechsler Adult Intelligence Scale<br />

WDS wavelength dispersive spectrometers<br />

WHO World Health Organization<br />

WISC Wechsler Intelligence Scale <strong>for</strong> Children<br />

WISC-R Wechsler Intelligence Scale <strong>for</strong> Children-Revised<br />

WO whole organism<br />

WRAT-R Wide Range Achievement Test-Revised<br />

WT wild type<br />

WTHBF-6 human liver cell line<br />

ww wet weight<br />

XAFS X-ray absorption fine structure<br />

XANES X-ray absorption near edge spectroscopy<br />

XAS X-ray absorption spectroscopy<br />

XPS X-ray photoelectron spectroscopy<br />

X-rays synchrotron radiation<br />

XRD X-ray diffraction<br />

XRF X-ray fluorescence<br />

ZAF correction in reference to three components <strong>of</strong> matrix effects:<br />

atomic number (Z), absorption (A), and fluorescence (F)<br />

ZnNa2 DTPA zinc disodium diethylenetriaminepentaacetic acid<br />

ZnNa2 EDTA zinc disodium ethylenediaminetetraacetic acid<br />

ZPP zinc protoporphyrin<br />

<strong>II</strong>-l


AX5. CHAPTER 5 ANNEX<br />

ANNEX TABLES AX5-2<br />

AX5-1


AX5-2<br />

Table AX5-2.1. Effect <strong>of</strong> <strong>Lead</strong> on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

Pb nitrate<br />

0–100 µM,<br />

Free Pb 2+<br />

0–20 µM,<br />

In vitro<br />

Pb nitrate<br />

1.5 mM<br />

In vitro<br />

10 µM Pb,<br />

as Pb acetate,<br />

In vitro<br />

100 µg/dL Pb,<br />

10 mg/dL, Pb,<br />

In vitro<br />

2 µM Pb acetate<br />

2 µM Pb<br />

10 or 20 mM Pb<br />

acetate, i.p. once a<br />

week (100 or<br />

200 µmoles)/ kg b.wt.<br />

(a) Pb recovery<br />

studies,<br />

10 min<br />

(b) Relationship<br />

<strong>of</strong> free Pb 2+ to<br />

added Pb,<br />

20 min<br />

Erythrocyte cell lysates from<br />

humans<br />

— Uptake and transport <strong>of</strong> Pb in erythrocyte and across erythrocyte cell<br />

membrane under the influence <strong>of</strong> varying buffers and ions.<br />

a. Pb can cross the membrane passively in either direction.<br />

Influx and efflux show similar properties<br />

b. Passive transport <strong>of</strong> Pb is strongly stimulated by HCO3 !<br />

(bicarbonate)<br />

c. Pb uptake is unaffected by varying the external concentrations <strong>of</strong><br />

Na + , K + , and Ca 2+<br />

d. In RBC, Pb binds mainly to hemoglobin. The ratio <strong>of</strong> bound Pb<br />

to free Pb 2+ in the cytosol is estimated 6000:1<br />

1 h Human erythrocytes — Pb uptake and transport are studied in resealed erythrocyte ghosts.<br />

a. Transport <strong>of</strong> Pb across erythrocyte membranes is passive<br />

b. 90% <strong>of</strong> Pb uptake by erythrocytes is inhibited by drugs that block<br />

anion transport, indicating the involvement <strong>of</strong> anion exchanges<br />

c. Pb transport depends upon the presence <strong>of</strong> a second anion. In the<br />

presence <strong>of</strong> HCO3 ! , the rate is stimulated in the order <strong>of</strong> ClO4 !<br />


AX5-3<br />

Table AX5-2.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

20 mM Pb acetate,<br />

i.p. once a week<br />

(200 µmoles/kg b.wt)<br />

200 µM <strong>of</strong> Pb acetate,<br />

i.p.<br />

Pb, i.p. 20 mg/ kg<br />

b.wt.<br />

5 wks Male<br />

Wistar Albino rats<br />

Once a week <strong>for</strong><br />

5 wks<br />

14 consecutive<br />

days<br />

Control:<br />

1–12 µg/100 mL<br />

Exposed:<br />

100–800 :g/dL<br />

Exposure to Pb significantly decreased RBC membrane sialic acid<br />

content, erythrocyte survival, hemoglobin, and hematocrit. This was<br />

evident to a minor extent below blood Pb levels 100 µg/100 mL and<br />

was generally present from 100 µg/100 mL and higher.<br />

Rat 0–600 µg/dL Pb exposure significantly decreases RBC count, Hb values,<br />

hematocrit, mean corpuscular volume, and mean corpuscular<br />

hemoglobin, decreases erythrocyte mobility, membrane sialic acid<br />

content, and de<strong>for</strong>mability.<br />

Male<br />

Albino rat<br />

1 µM Pb nitrate 1 h Erythrocytes from Pb-exposed<br />

healthy humans<br />

1 µM Pb nitrate,<br />

In vitro<br />

0.1–200 :M,<br />

Pb nitrate in the<br />

reaction buffer<br />

0.1–10 µM Pb ions<br />

from 10 mM<br />

Pb(NO3)2 solution,<br />

In vitro<br />

1 h Erythrocytes from healthy<br />

human volunteers<br />

6 and 12 mo Erythrocytes from Pb-exposed<br />

rats<br />

Controls:<br />

8.3 µg/dL<br />

Exposed:<br />

70.5 µg/dL<br />

Acetyl choline esterase (AchE), NADH dehydrogenase, and Na + -K +<br />

ATPase activities in rat erythrocyte membranes were inhibited by Pb<br />

exposure. Erythrocyte membrane sialic acid, hexose, hexosamine<br />

were inhibited by Pb exposure. Membrane phospholipids and<br />

cholesterol were increased.<br />

Pb exposure in healthy human RBC membranes resulted in increased<br />

levels <strong>of</strong> arachidonic acid (AA). The increase in AA correlated in a<br />

dose dependent manner with elevation in Pb and with serum iron.<br />

On the other hand, a negative correlation was found between Aa and<br />

serum calcium. It is inferred that substitution <strong>of</strong> Pb to calcium,<br />

which is essential <strong>for</strong> the release <strong>of</strong> phospholipase A2 <strong>for</strong> AA release<br />

may be the reason <strong>for</strong> increased RBC membrane AA.<br />

— Pb inhibits Gordos effect in human erythrocytes; electron spin<br />

labeling studies indicated cell shrinkage and decreased volume.<br />

Cation-osmotic hemolysis (COH) in 12 mo Pb-exposed rats was<br />

lower in the areas <strong>of</strong> lower ionic strength on erythrocyte membranes.<br />

1–6 h In vitro, human erythrocytes — Pb crosses the erythrocyte membrane by the anion exchanger and<br />

can also leave erythrocytes by a vanadate–sensitive pathway,<br />

identified with the calcium pump. The high ratio <strong>of</strong> erythrocyte to<br />

plasma Pb seen in vivo appeared to be due to the presence <strong>of</strong> a labile<br />

Pb2+- binding component present in erythrocyte cytoplasm.<br />

24 h Erythrocytes from healthy<br />

human volunteers<br />

— Pb activates erythrocyte K + channels, Ca 2+ sensitive erythrocyte<br />

Scramblase, triggers Phosphatidyl serine receptors and result in cell<br />

shrinkage and decreased life span.<br />

Terayama and<br />

Muratsuga (1988)<br />

Terayama (1993)<br />

Jehan and Motlag<br />

(1995)<br />

Osterode and Ulberth<br />

(2000)<br />

Eriksson and Beving<br />

(1993)<br />

Mojzis and Nistiar<br />

(2001)<br />

Simons (1993a)<br />

Kempe et al. (2005)


AX5-4<br />

Table AX5-2.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

20 µM Pb ion,<br />

In vitro<br />

20 µM Pb ions,<br />

In vitro<br />

Erythrocytes from<br />

Pb-exposed workers<br />

24–45 yr old white<br />

males<br />

0.1 mM Pb final<br />

concentration,<br />

In vitro<br />

1–10 µM Pb acetate,<br />

In vitro<br />

0–1200 nM Pb,<br />

In vitro<br />

2 min–2 h Erythrocytes from human<br />

umbilical cord<br />

1 h Human umbilical cord<br />

erythrocytes<br />

Duration <strong>of</strong><br />

exposure not<br />

given. RBCs<br />

were isolated.<br />

Experiments<br />

were per<strong>for</strong>med<br />

in ghosts and<br />

resealed<br />

membranes<br />

— Pb attenuates prolytic effect on neonatal erythrocytes in iso-or<br />

hypotonic low ionic strength media.<br />

Hemolytic activity <strong>of</strong> Organo Pbs increases with their<br />

hydrophobicity: triethyl Pb chloride < tri-n-propyl Pb chloride<br />

< tributyl tin chloride.<br />

— Pb ions increase the resistance to lysis in media <strong>of</strong> diminishing<br />

tonicity. These changes might be mediated by changes in membrane<br />

structure.<br />

Humans 1.17–1.54 µM Increased blood Pb in exposed workers was associated with a<br />

significant decrease in the average microviscosity <strong>of</strong> resealed and<br />

unsealed erythrocyte membranes. Alterations in the microviscosity<br />

<strong>of</strong> the lipid regions <strong>of</strong> the hydrophobic core <strong>of</strong> the erythrocyte<br />

membrane bilayer and in the phospholipid composition <strong>of</strong> the<br />

membrane may be defects that contribute to the clinical and<br />

biochemical alterations/effects.<br />

1 h Erythrocytes from healthy<br />

humans<br />

3 h Erythrocytes from healthy<br />

humans<br />

1 h Erythrocytes from healthy<br />

humans<br />

— Pb particles adhere to the external and internal surfaces <strong>of</strong> the human<br />

erythrocyte membrane and disturb the lamellar organization <strong>of</strong> lipid<br />

bilayers.<br />

— Low concentrations <strong>of</strong> Pb alter the physicochemical properties <strong>of</strong><br />

proteins and lipids in erythrocyte membranes.<br />

— Significant increase in the phosphorylation <strong>of</strong> membrane cytoskeletal<br />

proteins in Pb treated human erythrocytes at concentrations above<br />

100 nM mediated by enhanced PKC activity.<br />

Serrani et al. (1997)<br />

Kleszcyńska et al.<br />

(1997)<br />

Corchs et al. (2001)<br />

Cook et al. (1987)<br />

Suwalsky et al. (2003)<br />

Slobozhanina et al.<br />

(2005)<br />

Belloni-Olivi et al.<br />

(1996)


AX5-5<br />

Table AX5-2.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

Occupational,<br />

Human exposure<br />

— — a. 24 adult healthy controls<br />

(humans)<br />

b. 12 patients with Pb<br />

poisoning (plumbism)<br />

symptoms (Pb controls)<br />

c. Patients with chronic renal<br />

failure (CRF)<br />

Divided into:<br />

1. Normal urinary blood Pb<br />

levels<br />

2. High urinary blood Pb<br />

levels<br />

— a. 28 male workers in a Pb<br />

refining factory<br />

b. Controls<br />

Controls:<br />

!17.1 µg/dL<br />

Pb controls:<br />

80.5 µg/dL<br />

CRF !1:<br />

18.4 µg/dL<br />

CRF !2:<br />

18.0 µg/dL<br />

Urinary Pb CRF 1:<br />

!322 µg/72 h<br />

CRF 2:<br />

1785 µg/72 h<br />

Exposed:<br />

!35.97 µg/100 g<br />

Controls:<br />

5.23 µg/100 g<br />

Increased erythrocyte Zn protoporphyrin to free protoporphyrin<br />

ratio in Pb controls and remained in the normal range in CRF<br />

patients. CRF patients showed minor abnormalities <strong>of</strong> erythrocyte<br />

heme metabolism, such as low ALAD activity.<br />

SDS polyacrylamide electrophoresis <strong>for</strong> erythrocyte membrane<br />

proteins showed bands at 3 and 4.1, that significantly decreased<br />

while bands 2.3, 6, and 7 significantly increased in the Pb workers<br />

compared with controls.<br />

RBC—Red blood cells; Hb—Hemoglobin; NADH—Nicotinamide adenine dinucleotide dehydrogenase; PKC—Protein kinase C; AchE—Acetyl choline esterase<br />

Fontanellas et al.<br />

(2002)<br />

Fukumoto et al.<br />

(1983)


AX5-6<br />

Table AX5-2.2. <strong>Lead</strong>, Erythrocyte Heme Enzymes, and Other Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

Dietary,<br />

0–100 µg/g dry wt. <strong>of</strong><br />

the diet<br />

Pb acetate, oral<br />

gavage, 1.5 mg/kg<br />

b.wt, Pb acetate<br />

20 µg/mL as Pb<br />

acetate in drinking<br />

water<br />

17 µM Me/kg Pb<br />

acetate, Per OS<br />

1.5 mg Pb/kg body<br />

wt, oral dose<br />

Occupational<br />

exposure<br />

35 days Adult male Zebra finches 0–1.5 µg/mL Significant negative correlation was observed between blood-Pb<br />

concentration and log ALAD activity. RBC ALAD activity ratio is<br />

a sensitive indicator <strong>of</strong> dietary Pb concentration regardless <strong>of</strong> the<br />

mode <strong>of</strong> exposure.<br />

3 or 11 wks Red-tailed Hawks 0.195–<br />

0.752 µg/dL<br />

Erythrocyte phorphobilinogen synthetase was depressed<br />

significantly with in the 1st wk <strong>of</strong> treatment. Rapid but brief<br />

increase in free protoporphyrin. Hematocrit, erythrocyte count, Hb<br />

were all decreased and blood viscosity increased in exposed group.<br />

5 wks Female Wistar Albino rats 37.8 µg/dL Pb exposure decreases hematocrit, hemoglobin, and the number <strong>of</strong><br />

erythrocytes and enhances blood viscosity.<br />

5 days Female<br />

Rabbits<br />

8 yrs Cynomolgus Monkey,<br />

in vitro<br />

Dogs from urban and rural<br />

areas <strong>of</strong> Greece<br />

11–22 yrs Human erythrocytes from<br />

exposed populations<br />

0–20 mg Pb liter !1 29 days Juvenile Rainbow trout<br />

erythrocytes<br />

— Pb causes a significant decrease in blood ALAD activity, increases<br />

free erythrocyte protoporphyrins, increases aminolevulinic acid<br />

and coporphyrin excretion in urine.<br />

— Kinetic analyses <strong>of</strong> erythrocyte *- aminolevulinic acid revealed<br />

differences in P H optimum and Michaelis constants with Pb<br />

exposure. The ALAD enzyme kinetics <strong>of</strong> Pb exposed monkeys<br />

and humans are similar.<br />

326, 97–68 µg/L Significant negative correlation existed between blood-Pb levels<br />

and ALAD activity. 807–992 µmol/PBG/LRBC/h is established as<br />

the normal erythrocyte ALAD range <strong>for</strong> dogs.<br />

1.39–1.42 µmol/l Liquid chromatography with inductively coupled plasma<br />

spectrometry had revealed ALAD to be the principle Pb binding<br />

protein. The percentage <strong>of</strong> Pb bound to ALAD was influenced by<br />

a common polymorphism in the ALAD gene.<br />

— Significant decreases in the erythrocyte ALAD activity after a 29days<br />

exposure to 121 and 201 mg Pb liter !1.<br />

Scheuhammer et al.<br />

(1987)<br />

Redig et al. (1991)<br />

Toplan et al. (2004)<br />

Zareba and<br />

Chmelnicka (1992)<br />

Dorward and<br />

Yagminas (1994)<br />

Polizopoulou et al.<br />

(1994)<br />

Bergdahl et al. (1997)<br />

Burden et al. (1998)


AX5-7<br />

Table AX5-2.2 (cont’d). <strong>Lead</strong>, Erythrocyte Heme Enzymes, and Other Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

Pb acetate 160 mg/L<br />

in water<br />

1.46 µmol/liter,<br />

In vitro<br />

Pb 0.34 µM/L–<br />

1.17 µM/L,<br />

subcutaneous<br />

injection<br />

0–60 pM Pb ion,<br />

In vitro<br />

200–500 ppm Pb in<br />

drinking water<br />

0.1–100 µM Pb ion,<br />

In vitro<br />

20–5 µg/kg body wt<br />

1 mg/ kg body wt<br />

8 wks Wistar rats $20!$40 µg/dL Pb increases blood and liver Pb, erythrocyte porphyrin content,<br />

hypoactivity <strong>of</strong> both hepatocytic and erythrocytic ALAD.<br />

— Fish from regions close to<br />

the smelters and down stream<br />

48 h Human whole blood<br />

erythrocyte hemolysates,<br />

normal and Pb intoxicated<br />

individuals<br />

1 h Male albino New Zealand<br />

rabbits<br />

— Smelter site fish had elevated Pb concentrations, decreased ALAD<br />

activity and species differences in this inhibitory activity were<br />

apparent that could be attributed to Zn levels.<br />

— The effects <strong>of</strong> various divalent cations on erythrocyte<br />

porphobilinogen are concentration and PH dependent. Zn restores<br />

the Pb inhibited activity.<br />

— Pb causes the most inhibition and Zn activation <strong>of</strong> rabbit Erythrocyte<br />

porphobilinogen activity.Cu 2+ , Cd 2+ , and Hg 2+ are intermediary.<br />

Each divalent ion has a characteristic effect on the PH- activity<br />

relationship <strong>of</strong> PBG-S.<br />

20 min Human erythrocyte lysates — Human erythrocyte lysate porphobilinogen activity is increased by<br />

Zn 2+ with a Km <strong>of</strong> 1.6 pM and inhibited by Pb with a Ki <strong>of</strong> 0.07 pM,<br />

Pb reduced the affinity <strong>for</strong> the substrate 5- aminolevulinate, non-<br />

competitively.<br />

14 or 30 days Male ddY mice 24–51 µg/100 mL Pb inhibits erythrocyte and bone marrow P5’N activity. Erythrocyte<br />

ALAD activity was inhibited by 90%. Elevation <strong>of</strong> Urinary<br />

excretion <strong>of</strong> ALA with no change in erythrocyte protoporphyrin and<br />

urinary co porphyrin as against in the Pb exposed humans indicates<br />

that protoporphyrin metabolism might be more resistant to Pb in<br />

mice than humans.<br />

5 min Human erythrocyte ghosts — Under normal incubation conditions Pb inhibits, Ca 2+ -Mg 2+ ATPase<br />

with an IC50 <strong>of</strong> 6.0µM. Pb inhibits Ca 2+ - Mg 2+ ATPase related to<br />

sulphahydryl groups above 1.0 µM Pb and by direct action <strong>of</strong> Pb<br />

upon Calmodulin below 1.0 µM.<br />

Pregnancy<br />

through lactation<br />

Erythrocytes from Sprague-<br />

Dawley rats<br />

— Na 2+ - K + - ATPase and Ca 2+ - Mg + - ATPase <strong>of</strong> erythrocyte membranes<br />

from Pb-depleted animals did not change in P0 generation as<br />

compared to 1 mg/kg b.wt Pb animals, where as in F1 generation Pb<br />

depleted rats showed reduced activity.<br />

Santos et al. (1999)<br />

Schmitt et al. (2002)<br />

Farant and Wigfield<br />

(1987)<br />

Farant and Wigfield<br />

(1990)<br />

Simons (1995)<br />

Tomokuni et al.<br />

(1989)<br />

Mas-Oliva (1989)<br />

Eder et al. (1990)


AX5-8<br />

Table AX5-2.2 (cont’d). <strong>Lead</strong>, Erythrocyte Heme Enzymes, and Other Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

20 mg Pb acetate/kg<br />

b.wt, i.p,<br />

In vivo<br />

10–200 µg/dL Pb ions<br />

(Pb acetate),<br />

In vitro<br />

Pb acetate through<br />

water or i.p. 1 or<br />

2 mg/Kg b.wt.<br />

14 days Male Albino rats<br />

erythrocytes<br />

20 h Human umbilical cord<br />

erythrocytes<br />

Every 4th day<br />

<strong>for</strong> 1 mo<br />

Wistar rats 1.51–<br />

35.31 µg/dL<br />

— Pb significantly decreases erythrocyte membrane acetyl choline esterase,<br />

NADH dehydrogenase, membrane sialic acid, hexose, and hexosamine.<br />

Pb ions inhibit aerobic glycolysis and diminish ATP level in human<br />

erythrocytes in vitro. Magnesium partly abolishes these effects by<br />

stimulating Magnesium dependent enzymes. Effect is seen both by<br />

direct addition <strong>of</strong> Pb acetate to erythrocyte ghosts as well as in the ghosts<br />

obtained after preincubation <strong>of</strong> erythrocytes with Pb acetate. Ca 2+ , Mg 2+<br />

ATPase is less sensitive and Mg ATPase is practically insensitive to Pb<br />

under these conditions.<br />

— Pb significantly decreased the concentration <strong>of</strong> ATP, ADP, AMP,<br />

adenosine, GTP, GDP, GMP, Guanosine, IMP, inosine, hypoxanthine,<br />

NAD and NADP concentrations.<br />

The concentrations <strong>of</strong> adenosine tri phosphate (ATP), Guanosine<br />

triphosphate (GTP), Nicotinamide adenine dinucleotide NAD + ,<br />

nicotinamide adenine dinucleotide phosphate NADP + adenylate and<br />

Guanylate (AEC and GEC) were significantly reduced in erythrocytes <strong>of</strong><br />

exposed animals. Results indicate Pb ions disrupt erythrocyte energy<br />

pathway.<br />

Jehan and Motlag<br />

(1995)<br />

Grabowska and<br />

Guminska (1996)<br />

Baranowska-Bosiacka<br />

and Hlynczak (2003)<br />

Baranowska-Bosiacka<br />

and Hlynczak (2004)<br />

ALAD — Aminolevulinic acid; Cu 2+ —Copper; Cd 2+ —Cadmium; Hg 2+ —Mercury; PBG-S Porphobilinogen synthetase; Zn—Zinc; ATP—Adenosine triphosphate; ADP—Adenosine diphosphate;<br />

AMP—Adenosine monophosphate; GTP—Guanosine tri phosphate; GDP—Guanosine diphosphate; GMP—Guanosine monophosphate; IMP—Inosine monophosphate; NAD—Nicotinamide<br />

adenine dinucleotide; NADP—Nicotinamide adenine dinucleotide phosphate.


AX5-9<br />

Table AX5-2.3. <strong>Lead</strong> Binding and Transport in Human Erythrocytes<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

0–60 pM Pb ion,<br />

In vitro<br />

Zn—Zinc<br />

20 min Human erythrocyte lysates — Human erythrocyte lysate porphobilinogen activity is increased by Zn 2+<br />

with a Km <strong>of</strong> 1.6 pM and inhibited by Pb with a Ki <strong>of</strong> 0.07 pM, Pb<br />

reduced the affinity <strong>for</strong> the substrate 5- aminolevulinate, non-<br />

competitively.<br />

Simons (1995)


AX5-10<br />

Table AX5-2.4. <strong>Lead</strong> Effects on Hematological Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

4-6 mg/Kg b.wt, i.p.,<br />

daily<br />

0.82 mg Pb/kg<br />

b.wt./d, oral gavage<br />

17 µM Me/Kg b.wt<br />

Pb acetate or 3.5 mg<br />

<strong>of</strong> Pb/kg body wt, i.p<br />

17 µM Me/Kg b.wt<br />

Pb acetate or 3.5 mg<br />

<strong>of</strong> Pb/ kg body wt, i.p.<br />

or per OS 17.5 mg/kg<br />

b.wt single injection<br />

Cu deficient 1 mg<br />

Cu/Kg<br />

Marginal deficient<br />

2 mg/kg<br />

Control 5 mg Cu/Kg<br />

High Zn 60 mg/kg.<br />

0.02–40 ppm Pb,<br />

dietary<br />

20 µg/mL, Pb acetate<br />

in drinking water<br />

15 and 30 days Intact and splenctamized rats — Pb increases urinary *-amino levulinic acid (ALA) excretion,<br />

depletion in RBC hemoglobin content, and more number <strong>of</strong><br />

reticulocytes in peripheral blood, and results in accumulation <strong>of</strong><br />

immature erythrocytes both in intact and splenctomized rats.<br />

3 or 11 wks Red-tailed hawks erythrocytes 0.195–0.375 mg/mL Activity <strong>of</strong> porphobilinogen synthase/ALAD was depressed<br />

significantly in Pb exposed rats and did not return to normal<br />

values until 5 wks after the termination <strong>of</strong> the treatment. A rapid<br />

and relatively brief increase in erythrocyte free proto porphyrin<br />

and a slower, prolonged increase in Zn complex.<br />

5 days Female Rabbits 17.5 µg/dL Pb causes a significant inhibition <strong>of</strong> ALAD in the blood ,<br />

increases free erythrocyte protoporphyrin, and urinary excretion<br />

<strong>of</strong> Aminolevulinic acid and coporphyrin.<br />

5 days i.p. Female Rabbits — Pb induced ALAS activity in liver and kidney, both after i.p and<br />

p.o. administration; i.p. administration <strong>of</strong> Pb also induced kidney<br />

heme oxygen levels.<br />

4 wks Rat — Moderately high Zn in the diet reduces plasma copper but not<br />

plasma ceruloplasmin.<br />

Does not affect the recovery <strong>of</strong> plasma Cu or activity after oral<br />

copper sulphate in Cu deficient diets.<br />

Does not influence RBC Super oxide dismutase activity.<br />

90 days Male and female Swiss mice 0.7–13.0 µg/dL Increased RBC number and increased hemoglobin and decreased<br />

hematocrit up on Pb exposure.<br />

5 wks Female Wistar Albino rats 37.8 µg/dL Erythrocyte count, hematocrit and hemoglobin were all decreased<br />

and blood viscosity increased in Pb exposed workers.<br />

Gautam and<br />

Chowdhury (1987)<br />

Redig et al. (1991)<br />

Zareba and<br />

Chmielnicka (1992)<br />

Chmielnicka et al.<br />

(1994)<br />

Panemangalore and<br />

Bebe (1996)<br />

Iavicoli et al. (2003)<br />

Toplan et al. (2004)


AX5-11<br />

Table AX5-2.4 (cont’d). <strong>Lead</strong> Effects on Hematological Parameters<br />

Dose and Route <strong>of</strong><br />

Exposure Duration Species Blood lead Effect Authors<br />

Erythrocytes from<br />

humans <strong>of</strong><br />

occupational Pb<br />

exposure and controls<br />

In vivo and in vitro<br />

In vivo; exposure<br />

In vitro assays on<br />

erythrocytes from<br />

exposed populations<br />

— Male Pb workers and<br />

13 normal volunteers<br />

— 1. Workers exposed to<br />

manganese (Mn) and<br />

2. Workers exposed to Pb<br />

without clinical<br />

manifestations <strong>of</strong><br />

intoxication<br />

Range 20.6–<br />

71.3 µg/dL<br />

Nicotinamide adenine dinucleotide synthetase activity in the Pb workers<br />

ranged from 0.08 to 1.1 µmol/h per g <strong>of</strong> hemoglobin. 50% <strong>of</strong> enzyme<br />

inhibition was observed at 40 µg/dL. Aminolevulinic acid dehydratase<br />

activity decreased rapidly and reached a plateau at Pb-B levels 40-60<br />

µg/dL. 50% <strong>of</strong> enzyme activity inhibition was observed at 20 µg/dL.<br />

— Erythrocyte concentrations <strong>of</strong> adenyl nucleotides (ADP and ATP) were<br />

elevated in both groups <strong>of</strong> workers and that <strong>of</strong> AMP in Pb-exposed<br />

workers. The ratio <strong>of</strong> ATP/ADP significantly increased in Pb-exposed<br />

workers.<br />

ALA—Aminolevulinic acid; ALAS—Aminolevulinic acid synthetase; ALAD—Aminolevulinic acid dehydratase, RBC—Red blood cells.<br />

Morita et al. (1997)<br />

Nikolova and<br />

Kavaldzhieva et al.<br />

(1991)


AX5-12<br />

Table AX5-2.5. <strong>Lead</strong> Interactions with Calcium Potassium in Erythrocytes<br />

Dose and Route <strong>of</strong><br />

exposure Duration Species Blood lead Effect Authors<br />

0–325 µM, Pb nitrate,<br />

In vitro<br />

0 µM–5 mM Pb,<br />

In vitro<br />

1–4 µM Pb acetate,<br />

In vitro<br />

1–50 µM Pb ion,<br />

In vitro<br />

Pb depleted rats<br />

Pb concentration<br />


AX5-13<br />

Table AX5-2.6. <strong>Lead</strong>, Heme, and Cytochrome P–450<br />

Dose and Route <strong>of</strong><br />

exposure Duration Species Blood lead Effect Authors<br />

0–75 mg <strong>of</strong> Pb 2+ /Kg b.<br />

wt. i.p., Single<br />

injection<br />

EROD—Ethoxy resorufin-O-dealkylase.<br />

CYp3a11—Cytochrome P-450 3a11.<br />

0–30 h C57 BL/6 male mice — Pb causes an increase in *-amino levulinic acid levels in plasma and a<br />

decrease in the heme saturation <strong>of</strong> hepatic tryptophan -2,3 dioxygenase.<br />

P-450- dependent activities, EROD and O-dealkylation <strong>of</strong><br />

alkoxyresorufins decreased progressively. Pb exposure decreased<br />

mRNA levels <strong>of</strong> the P450 CYp3a11. The decrease in P450 transcription<br />

was a mechanism dependent on heme by inhibition <strong>of</strong> heme synthesis<br />

and also by a mechanism independent <strong>of</strong> heme in which Pb decreases P-<br />

450 transcription.<br />

Jover et al. (1996)


AX5-14<br />

Table AX5-2.7. <strong>Lead</strong>, Erythrocyte Lipid Peroxidation, and Antioxidant Defense<br />

Dose and Route <strong>of</strong><br />

exposure Duration Species Blood lead Effect Authors<br />

7.5 mg <strong>of</strong> Pb acetate<br />

or 4.09 mg <strong>of</strong> Pb<br />

Kg -1 b.wt, oral<br />

5.46 mg Pb as Pb<br />

acetate, oral<br />

10 mg/kg b.wt Pb<br />

acetate, intra<br />

muscular, daily<br />

Pre treatment with<br />

melatonin<br />

A. ALA 40 mg/kg<br />

b.wt every other day<br />

and/or<br />

B. Melatonin<br />

10 mg/kg<br />

Pb acetate 0.2%, in<br />

drinking water,<br />

followed by<br />

individual or<br />

combined treatment <strong>of</strong><br />

lipoic acid (25 mg/Kg<br />

b.wt and DMSA<br />

20 mg/kg b.wt, i.p.)<br />

*-Aminolevulinic<br />

acid, 1-5 mM, In vitro<br />

28 days,<br />

multiple<br />

analyses at day<br />

7, 14, 21, and 28<br />

14 days,<br />

multiple<br />

analyses at day<br />

0, 7, and 14<br />

Erythrocytes from male Calves 0.1–1.6 ppm Pb exposure significantly reduced erythrocyte super oxide dismutase<br />

activity until day 21 followed by a marginal increase by day 28. Total,<br />

protein-bound and non protein- bound –SH content <strong>of</strong> erythrocytes<br />

declined.<br />

Erythrocytes from female goats 0.09–1.12 ppm Pb exposure caused a significant increase <strong>of</strong> erythrocytic GPx, SOD and<br />

CAT activities, total thiol groups and total antioxidant status.<br />

7 days Rat — Pb significantly decreased heme synthesis, decreased Hb, decreased liver<br />

*- ALAS and erythrocyte ALAD. Markedly elevates hepatic lipid<br />

peroxidation, reduced anti oxidant enzymes such as total sulphahydryl<br />

groups and Glutathione. Pre Treatment with melatonin reduced the<br />

inhibitory effect <strong>of</strong> Pb on both enzymatic and non enzymatic<br />

antioxidants and reduced the iron deficiency caused by Pb.<br />

Every other day<br />

3 times daily <strong>for</strong><br />

2 wks<br />

Male Sprague- Dawley rats — Melatonin effectively protects nuclear DNA and lipids in rat lung and<br />

spleen against the oxidative damage caused by the carcinogen ALA.<br />

5 wks Male Albino rats 97.5 µg/dL Pb exposure results in decreased blood hemoglobin, hematocrit,<br />

enhanced erythrocyte membrane lipid peroxidation, decline in the<br />

activities <strong>of</strong> erythrocyte membrane Na + -K + ATPase, Ca 2+ ATPase, and<br />

Mg 2+ ATPase. Treatment with lipoic acid and/or DMSA reduced the Pb<br />

induced adverse changes in the biochemical parameters.<br />

10 days CHO cells — *- Aminolevulinic acid treatment induces oxidative stress in Chinese<br />

hamster ovary cells by inducing Glutathione, Glutathione disulphide,<br />

Malandialdehyde equivalents, and Catalase. N-acetyl cysteine<br />

administration reverses the decrease in cell survival and colony<br />

<strong>for</strong>mation induced by *- ALA.<br />

Patra and Swarup<br />

et al. (2000)<br />

Mousa et al. (2002)<br />

El- Missiry (2000)<br />

Karbownik et al.<br />

(2000)<br />

Sivaprasad et al.<br />

(2003)<br />

Neal et al. (1997)<br />

SOD—Super oxide dismutase; CAT—Catalase; ALAS—Aminolevulinic acid synthatase, ALAD—Aminolevulinic acid dehydratase; ALA—Aminolevulinic acid; GPx—Glutathione peroxidase


ANNEX TABLES AX5-3<br />

AX5-15


AX5-16<br />

Subject Exposure Protocol<br />

Rat<br />

PND 16–18<br />

Rat<br />

PND 50<br />

Rat<br />

PND 7, 14, 21,<br />

28, and 50<br />

Rat<br />

PND 21<br />

Table AX5-3.1. Summary <strong>of</strong> Key Studies on Neurochemical Alterations<br />

Hippocampal cultures 0.1 and 1.0 µM<br />

Pb Cl 2<br />

1500 ppm Pb(Ac) 2<br />

chow 10 days be<strong>for</strong>e breeding and<br />

maintained to sacrifice<br />

1500 ppm Pb(Ac) 2<br />

chow 10 days be<strong>for</strong>e breeding and<br />

maintained to sacrifice<br />

750 ppm Pb(Ac) 2<br />

chow from GD 0 to PND 21<br />

Cultured PC12 cells 0.03–10 µM<br />

Pb(NO 3) 2<br />

Adult rat Water—0.1–1.0% Pb(Ac) 2<br />

from GD 15 to adult<br />

Adult rat Water—0.1–1.0% Pb(Ac) 2<br />

from GD 15 to adult<br />

Peak Blood Pb or<br />

[Pb] used Observed Effects Reference<br />

Pb blockage <strong>of</strong> IPSCs were partially reversible while EPSCs were not. Braga et al. (2004)<br />

31.9 µg/dL Decreases the NR1 subunit splice variant mRNA in hippocampus. Guilarte and<br />

McGlothan (2003)<br />

— Alters NMDAR subtypes and reduces CREB phosphorylation. Toscano et al. (2002)<br />

46.5 µg/dL Increased expression <strong>of</strong> nicotinic receptors. Jett et al. (2002)<br />

Pb acts as a high affinity substitute <strong>for</strong> calcium in catecholamine<br />

release.<br />

61.8 µg/100 mL Hippocampal GLU and GABA release exhibits biphasic effects from<br />

chronic Pb.<br />

Westerink and<br />

Vijverberg (2002)<br />

Lasley and Gilbert<br />

(2002)<br />

117.6 µg/100 mL NMDA receptor function is upregulated. Lasley et al. (2001)<br />

Cultured PC12 cells 0.53 µM Pb(Ac)2 PKC is involved in TH upregulation but not downregulation <strong>of</strong> ChAT. Tian et al. (2000)<br />

Embryonic rat Hippocampal neurons 100 fM–100 nM Decreases [Ca 2+ ]i and increases Ca 2+ efflux by a calmodulin-dependent<br />

mechanism.<br />

Rat 750 or 1500 ppm Pb(Ac)2<br />

chow from 10 days pre-mating to<br />

PND 14, 21, and 28<br />

Ferguson et al.<br />

(2000)<br />

61.1 µg/dL Dose-response effect between level <strong>of</strong> Pb and expression <strong>of</strong> NR1 gene. Guilarte et al. (2000)<br />

Cultured PC 12 cells 5–20 µM Pb(Ac) 2 Induces expression <strong>of</strong> immediate early genes but requires PKC. Kim et al. (2000)


AX5-17<br />

Subject Exposure Protocol<br />

Rat<br />

PND 50<br />

Table AX5-3.1 (cont’d). Summary <strong>of</strong> Key Studies on Neurochemical Alterations<br />

750 or 1500 ppm Pb(Ac) 2<br />

chow from 10 days pre-mating to<br />

PND 50<br />

Calcineurin in mixture 10–2000 pM<br />

Pb(NO 3) 2<br />

Adult rat Cerebrocortical membranes 0.01–4 µM<br />

free Pb(Ac) 2<br />

Adult rat<br />

PND 2<br />

0.2% Pb(Ac) 2<br />

in water and chow<br />

Peak Blood Pb or<br />

[Pb] used Observed Effects Reference<br />

31.9 µg/dL Reductions in NMDAR receptors result in deficits in LTP and spatial<br />

learning.<br />

Nihei et al. (2000)<br />

Has a stimulatory (low) and inhibitory (high) effect on calcineurin. Kern and Audesirk<br />

(2000)<br />

Pb binds to the NMDA receptor channel in a site different from zinc. Lasley and Gilbert<br />

(1999)<br />

52.9 µg/100 mL GLU and GABA release are inhibited independent <strong>of</strong> Pb exposure<br />

period.<br />

Rat Cultured hippocampal neurons 0.01–10 µM Pb Cl 2 Inhibits glutamatergic and GABAergic transmission via calcium<br />

channel.<br />

Rat<br />

PND 17<br />

Rat<br />

PND 7, 14, 21,<br />

28<br />

Rat<br />

PND 7, 14, 21,<br />

28<br />

Rat<br />

PND 22-adult<br />

Rat<br />

PND 28 56,<br />

112<br />

Cultured hippocampal neurons 0.1–10 µM Pb Cl 2 Increases tetrodotoxin-insensitive spontaneous release <strong>of</strong> GLU and<br />

GABA.<br />

750 ppm Pb(Ac) 2<br />

chow from 14 days pre-mating to<br />

experimental use<br />

750 ppm Pb(Ac) 2<br />

chow from 14 days pre-mating to<br />

experimental use<br />

Water—0.2% Pb(Ac) 2<br />

from GD 16 to PND 21<br />

Water—1000 ppm Pb(Ac)2<br />

from GD 4-use<br />

59.87 µg/dL NMDAR-2A subunit protein expression is reduced in the<br />

hippocampus.<br />

Lasley et al. (1999)<br />

Braga et al. (1999a)<br />

Braga et al. (1999b)<br />

Nihei and Guilarte<br />

(1999)<br />

59.87 µg/dL Alters the levels <strong>of</strong> NMDA receptor subunits mRNA in hippocampus. Guilarte and<br />

McGlothan (1998)<br />

— Induces loss <strong>of</strong> septohippocampal cholinergic projection neurons in<br />

neonates lasting into young adulthood.<br />

Bourjeily and<br />

Suszkiw (1997)<br />

39.6 µg/dL Significant increase in [ 3 H]MK-801 binding after chronic exposure. Ma et al. (1997)


AX5-18<br />

Subject Exposure Protocol<br />

Rat<br />

PND 21–adult<br />

50 or 150 ppm Pb(Ac)2<br />

water <strong>for</strong> 2 wks–8 mo<br />

Adult rat Water—0.2% Pb(Ac) 2<br />

from PND 0–adult<br />

Rat<br />

4 mo<br />

Rat<br />

PND 111<br />

Water—0.2% Pb(Ac) 2<br />

from GD 16 to PND 28<br />

Table AX5-3.1 (cont’d). Summary <strong>of</strong> Key Studies on Neurochemical Alterations<br />

Water at 50 ppm Pb(Ac)2<br />

<strong>for</strong> 90 days; start at PND 21<br />

Cultured bovine chromaffin cells Variable kind and<br />

concentration<br />

Peak Blood Pb or<br />

[Pb] used Observed Effects Reference<br />

28.0 µg/dL Differential effects in [ 3 H]MK-801 binding with dopamine and D 1<br />

agonists.<br />

Cory-Slechta et al.<br />

(1997a)<br />

37.2 µg/100 mL Presynaptic glutamatergic function in dentate gyrus is diminished. Lasley and Gilbert<br />

(1996)<br />

22.0 µg/dL Developmental Pb results in long-lasting hippocampal cholinergic<br />

deficit.<br />

Bielarczyk et al.<br />

(1996)<br />

18 µg/dL Decreases in vivo release <strong>of</strong> dopamine in the nucleus accumbens. Kala and Jadhav<br />

(1995)<br />

Exerts dual stimulatory and inhibitory effects on adrenal PKC. Tomsig and Suszkiw<br />

(1995)<br />

Rat Homogenized cortex Ranging Pb(Ac)2 Pb activates PKC in the range <strong>of</strong> 10 −11 to 10 −8 M. Long et al. (1994)<br />

Rat<br />

PND 14 or 56<br />

Cultured bovine chromaffin cells Variable kind and<br />

concentration<br />

Neuronal membranes Chow containing<br />

750 ppm Pb(Ac)2<br />

Rat Cortical synaptosomes 1–50 nM free Pb<br />

or 1 µM Pb(NO3) 2<br />

Pb and calcium activate the exocytotic release <strong>of</strong> norepinephrine. Tomsig and Suszkiw<br />

(1993)<br />

Review paper discussing Pb-calcium interactions in Pb toxicity. Simons (1993b)<br />

Review paper exploring Pb as a calcium substitute. Goldstein (1993)<br />

Inhibitory effect on [ 3 H]MK-801 binding and loss <strong>of</strong> binding sites in<br />

neonates.<br />

Guilarte and Miceli<br />

(1992)<br />

Triggers acetylcholine release more effectively than calcium. Shao and Suszkiw<br />

(1991)


AX5-19<br />

Subject Exposure Protocol<br />

Table AX5-3.1 (cont’d). Summary <strong>of</strong> Key Studies on Neurochemical Alterations<br />

Peak Blood Pb<br />

or [Pb] used Observed Effects Reference<br />

Rat Hippocampal neurons 2.5–50 µM Pb Cl 2 Pb has a blocking effect on the NMDA subtype <strong>of</strong> glutamate receptors. Alkondon et al.<br />

(1990)<br />

Rat Brain protein kinase C 10 −10 M Pb salts Stimulates brain protein kinase C and diacylglycerol-activated calcium. Markovac and<br />

Goldstein (1988b)<br />

Abbreviations<br />

GD—gestational day


AX5-20<br />

Subject Exposure Protocol<br />

Rat<br />

PND 22<br />

Rat<br />

PND 42–64<br />

Rat<br />

PND 130–210<br />

250 ppm Pb(Ac) 2<br />

3–6 wks (electro) or 7-13 wks<br />

(immuno)<br />

100, 250, or 500 ppm<br />

Pb(Ac) 2 in chow <strong>for</strong> 3-6 wks<br />

0.2% Pb(Ac)2<br />

in water<br />

Adult rat Water—0.1-1.0% Pb(Ac)2<br />

from GD 16 to adult<br />

Adult rat 0.2% Pb(Ac) 2<br />

in water<br />

Adult rat 0.2% Pb(Ac) 2<br />

in water PND 0-21<br />

Rat<br />

PND 90–130<br />

Table AX5-3.2. Summary <strong>of</strong> Key Studies on Neurophysiological Assessments<br />

750 ppm Pb(Ac) 2<br />

chow from 50 days pre-mating to<br />

experimental use<br />

Rat 7–18 mo Water—0.2% Pb(Ac) 2<br />

from GD 16 to experimental use<br />

Rat<br />

PND 13–140<br />

750 ppm Pb(Ac) 2<br />

chow from 50 days pre-mating to<br />

experimental use<br />

Peak Blood Pb<br />

or [Pb] used Observed Effects Reference<br />

30.8 µg/dL Reduces midbrain dopamine impulse flow and decreases dopamine D1<br />

receptor sensitivity in nucleus accumbens.<br />

Tavakoli-Nezhad<br />

and Pitts (2005)<br />

54.0 µg/dL Decrease in number <strong>of</strong> spontaneously active midbrain dopamine neurons. Tavakoli-Nezhad<br />

et al. (2001)<br />

Review paper examining glutamatergic components contributing to<br />

impairments in synaptic plasticity.<br />

Lasley and Gilbert<br />

(2000)<br />

75.4 µg/dL Deficits in synaptic plasticity in the dentate gyrus from early exposure. Gilbert et al.<br />

(1999a)<br />

117.6 µg/dL Biphasic dose-dependent inhibition <strong>of</strong> hippocampal LTP. Gilbert et al.<br />

(1999b)<br />

30.1 µg/dL Chronic Pb exposure significantly decreases range <strong>of</strong> synaptic plasticity. Zhao et al. (1999)<br />

30.1 µg/dL Impairments in LTP and paired-pulse facilitation in the hippocampal DG. Ruan et al. (1998)<br />

16.04 µg/100 mL NMDA-dependent <strong>for</strong>ms <strong>of</strong> synaptic plasticity are more vulnerable than<br />

NMDA-independent potentiation or paired pulse-facilitation.<br />

Gutowski et al.<br />

(1998)<br />

— Impairs ability to maintain LTP over time in the dentate gyrus. Gilbert and Mack<br />

(1998)<br />

28.5 µg/dL Paired-pulse stimulation <strong>of</strong> CA3 region shows inhibitory mechanisms. Gutowski et al.<br />

(1997)<br />

Adult rat Water—0.2% Pb(Ac)2<br />

from PND 0–adult<br />

— Chronic Pb increases the threshold <strong>for</strong> LTP in dentate gyrus in vivo. Gilbert et al.<br />

(1996)<br />

Rat<br />

PND 4–30<br />

Hippocampal neurons 1–100 µM Pb Cl2 Identified the nicotinic acetylcholine receptor as a target <strong>for</strong> Pb. Ishihara et al.<br />

(1995)<br />

Rat 750 ppm Pb(Ac) 2<br />

chow from 50 days pre-mating to<br />

experimental use<br />

16.2 µg/100 mL LTP and learning are impaired if exposed to Pb in the immature brain. Altmann et al.<br />

(1993)<br />

Abbreviations<br />

GD—gestational day


AX5-21<br />

Subject Exposure Protocol<br />

Mice<br />

PND 7–90<br />

Rat<br />

PND 21 or 90<br />

Monkey<br />

13 yrs<br />

Table AX5-3.3. Summary <strong>of</strong> Key Studies on Changes in Sensory Function<br />

0.15 % Pb(Ac) 2<br />

in dams water from PND 0–21<br />

Rat retinas 0.01–10 µM<br />

Pb Cl 2<br />

0.02% and 0.2% Pb(Ac) 2<br />

in dams water PND 0–21 and<br />

3 wks as adult<br />

2 mg/kg/d Pb(Ac) 2<br />

in capsule <strong>for</strong> 13 y<br />

Monkey 350 or 600 mg Pb(Ac) 2<br />

<strong>for</strong> 9.75 yrs<br />

Bovine retinas 50 pM–100 nM<br />

Pb(Ac)2<br />

Peak Blood Pb<br />

or [Pb] used Observed Effects Reference<br />

26 µg/dL Produces a rod photoreceptor-selective apoptosis inhibited by Bcl-xl<br />

overexpression.<br />

He et al. (2003)<br />

Pb and calcium produce rod photoreceptor cell apoptosis via mitochondria. He et al. (2000)<br />

59.0 µg/dL Functional alterations and apoptotic cell death in the retina. Fox et al. (1997)<br />

168.0 µg/dL Mild increase in detection <strong>of</strong> pure tones outside <strong>of</strong> threshold. Rice (1997)<br />

55 µg/dL Consistent prolongations <strong>of</strong> latencies on the brain stem auditory evoked<br />

potential.<br />

Lilienthal and<br />

Winneke (1996)<br />

Direct inhibition <strong>of</strong> purified rod cGMP PDE, magnesium can reverse effect. Srivastava et al.<br />

(1995)<br />

Rat retinas 10 −9 to 10 −4 M Alters several physiological and biochemical properties <strong>of</strong> rod photoreceptors. Fox et al. (1994)<br />

Adult rat 0.02% and 0.2% Pb(Ac)2<br />

in dams water PND 0–21<br />

Monkey 6 yr Glycerine capsule with 25 or<br />

2000 µg/kg/d Pb(Ac) 2<br />

Rat<br />

PND 90<br />

0.2% Pb(Ac) 2<br />

in dams water PND 0–21<br />

Review paper examining effects upon auditory and visual function. Otto and Fox<br />

(1993)<br />

59.4 µg/dL Inhibits adult rat retinal, but not kidney, Na + , K + -ATPase. Fox et al. (1991b)<br />

220 µg/dL Morphological damage in the visual cortical area V1 and V2. Reuhl et al.<br />

(1989)<br />

0.59 ppm Long-term selective deficits in rod photoreceptor function and biochemistry. Fox and Farber<br />

(1988)


AX5-22<br />

Subject<br />

Rat, female,<br />

22 wks<br />

Rat<br />

Wistar<br />

Rat, LE,<br />

postweaning<br />

Rat, LE, male<br />

Postweaning<br />

Rat, LE, male<br />

Postweaning<br />

Rat, LE, male<br />

Postweaning<br />

Exposure<br />

Protocol<br />

Table AX5-3.4. Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

75 or 300 ppm Pb(Ac) 2 39 µg/dL Significantly impaired on the alteration task with variable intertrial delays. Alber and Strupp<br />

(1996)<br />

750 ppm Pb(Ac) 2 15 µg/dL Pb-induced deficits in AAL in rats exposed to Pb either during pre-weaning<br />

or pre- and postweaning: postweaning-only exposure caused reduced deficits<br />

in AAL.<br />

50 ppm Pb(Ac)2 15.1 µg/dL Quinpirole at 0.05 mg/kg reversed the effects <strong>of</strong> Pb on FI per<strong>for</strong>mance;<br />

eticlopride had no effect on response rates in Pb-treated animals.<br />

50 or 150 ppm Pb <strong>for</strong> 3 mo 10.8 and<br />

28.5 µg/dL<br />

50 or 150 ppm Pb <strong>for</strong> 3 mo 9.7 and<br />

26.2 µg/dL after<br />

3 and 7 mo<br />

50 or 150 ppm Pb <strong>for</strong> 3 mo 16.0 and<br />

28.0 µg/dL<br />

FR: 150-ppm rats—significantly higher response rates and component resets<br />

than the low dose group and controls. Waiting behavior: wait time was lower<br />

in both treated groups. 150-ppm rats—increased number <strong>of</strong> rein<strong>for</strong>cers and a<br />

higher response to rein<strong>for</strong>cement ratio than low dose and controls.<br />

D2 agonist quinpirole reversed the Pb-induced effects on FR-response rate,<br />

FR resets, wait rein<strong>for</strong>cers, and wait time.<br />

Altmann et al.<br />

(1993)<br />

Areola and<br />

Jadhav (2001)<br />

Brockel and<br />

Cory-Slechta<br />

(1998)<br />

Brockel and<br />

Cory-Slechta<br />

(1999a)<br />

No Pb-induced effects on sustained attention. Brockel and<br />

Cory-Slechta<br />

(1999b)<br />

Rat, SD, adult 500 ppm Pb(Ac)2 20.9 µg/dL Chronic Pb exposure attenuated the rein<strong>for</strong>cing effect <strong>of</strong> brain stimulation. Burkey and<br />

Nation (1994)<br />

Rat, SD 0.2% Pb(Ac) 2 during gestation<br />

and lactation, postweaning<br />

only, or continuously<br />

PND 56: 3.8,<br />

25.3, and<br />

29.9 µg/dL<br />

No Pb-associated effects in learning per<strong>for</strong>mance with just maternal or<br />

postweaning exposure. Continually exposed rats tended to avoid less<br />

frequently and in two-way active avoidance training, did not respond<br />

more frequently.<br />

(Chen et al.<br />

(1997a)


AX5-23<br />

Subject<br />

Exposure<br />

Protocol<br />

Rat, SD 0.2% Pb(Ac) 2 during gestation<br />

and lactation, postweaning<br />

only, or continuously<br />

Rat, LE, male 50 or 250 ppm Pb(Ac) 2<br />

chronically from PND 21<br />

Rat, LE, male 50 or 250 ppm Pb(Ac)2<br />

chronically from PND 21<br />

Rat, LE, male 50 or 250 ppm Pb(Ac) 2<br />

in water PND 21-use<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

PND 56: 3.8,<br />

25.3, and<br />

29.9 µg/dL<br />

25.1 and<br />

73.5 µg/dL<br />

25.1 and<br />

73.5 µg/dL<br />

Rat, LE, male 50 or 500 ppm from weaning 30.3 and 58–<br />

94 µg/dL<br />

Rat, LE, male,<br />

PND 21<br />

50 ppm PbS<br />

8–11 mo<br />

6–8.5 mo 50 or 500 ppm<br />

3–5 mo<br />

Rat, LE, male,<br />

PND 21<br />

Rat, F344,<br />

PND 21<br />

8 mo,<br />

16 mo<br />

All Pb-treated groups: impaired learning acquisition but unimpaired memory<br />

retention; possible alterations in AMPA receptor binding.<br />

Pb-induced decrements in accuracy on the learning component, but not on the<br />

per<strong>for</strong>mance component compared; Pb exposure impaired learning by<br />

increasing preseverative responding on a single lever, even though such<br />

repetitive responding was not directly rein<strong>for</strong>ced.<br />

Pb exposure: attenuated the decline in learning accuracy and the increases in<br />

preseverative responding produced by MK-801; dose-effect curves relating<br />

MK-801 dose to changes in rates <strong>of</strong> responding were shifted to the right.<br />

73.5 µg/dL Pb-induced potentiation <strong>of</strong> the accuracy-impairing effects <strong>of</strong> NMDA by further<br />

increasing the frequencies <strong>of</strong> errors and likewise potentiated the drug’s ratesuppressing<br />

effect; learning impairments are not caused by changes in<br />

dopaminergic function.<br />

50-ppm group: no effects. 500-ppm group: response rates initially decreased,<br />

then reached control levels, primarily due to longer interresponse times.<br />

FI response rates are more sensitive to perturbation by Pb than FR.<br />

~20 µg/dL Decreased FI response rates (i.e., longer IRTs and lower running rates)<br />

compared to controls.<br />

Demonstrated no consistent changes in FI per<strong>for</strong>mance, suggesting that once a<br />

behavior has been acquired, it may be resistant to the adverse effects <strong>of</strong><br />

subsequent Pb exposure.<br />

Chen et al. (2001)<br />

Cohn et al. (1993)<br />

Cohn and Cory-<br />

Slechta (1993)<br />

Cohn and Cory-<br />

Slechta (1994a,b)<br />

Cory-Slechta<br />

(1986)<br />

Cory-Slechta<br />

(1990a)<br />

50 or 250 ppm Pb(Ac) 2 73.2 µg/dL Increased sensitivity to the stimulus properties <strong>of</strong> dopamine D 1 and D 2 agonists. Cory-Slechta and<br />

Widowski (1991)<br />

2 or 10 mL/kg/d Pb(Ac) 2 <strong>for</strong><br />

9.5 mo<br />

13–18 µg/dL<br />

steady state<br />

Young and old rats: increased VI and FI response rates; adult rats: decreased<br />

response rates on both schedules. Effects on FI seen with 2-mg dose and VI<br />

with only the 10-mg dose.<br />

Cory-Slechta<br />

and Pokora<br />

(1991)


AX5-24<br />

Subject<br />

Rat, F344,<br />

male<br />

Exposure<br />

Protocol<br />

2 or 10 mg/kg Pb(Ac) 2<br />

Rat, LE, male 100 or 350 ppm Pb(Ac) 2<br />

in dam’s water PND 0–21<br />

Rat, LE, male 50 or 150 ppm Pb(Ac) 2<br />

from weaning<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

2 mg: 23; 10 mg:<br />

42 (adult),<br />

~48 (old),<br />

~58 µg/dL<br />

(young)<br />

Aging caused impaired accuracy: In both young and old rats: Pb-induced<br />

increase in accuracy, at the longest delay periods (12 s) in young rats, and at the<br />

short delay periods in old rats. Adults: not affected by Pb exposure.<br />

Cory-Slechta<br />

et al. (1991)<br />

34 µg/dL Induced functional D2-D3 supersensitivity to the stimulus properties <strong>of</strong> agonist. Cory-Slechta<br />

et al. (1992)<br />

C Altered cholinergic sensitivity due to Pb and several agonists. Cory-Slechta and<br />

Pokora (1995)<br />

Rat, LE, male 50 or 150 ppm Pb(Ac) 2 35.7 µg/dL Postweaning Pb exposure resulted in an MK-801 subsensitivity. Cory-Slechta<br />

(1995)<br />

Rat, LE, male 50 or 150 ppm Pb(Ac)2<br />

in water PND 21-use<br />

Rat, LE, male 50 or 150 ppm Pb(Ac) 2<br />

from weaning<br />

Rat, LE, male 100 or 350 ppm Pb(Ac)2<br />

from weaning<br />

Rat, LE, male 50 or 500 ppm Pb(Ac) 2<br />

from weaning<br />

Rat, LE, male 50 or 500 ppm Pb(Ac) 2<br />

from weaning<br />

30.6 µg/dL (1) Enhances the stimulus properties <strong>of</strong> NMDA via a possible<br />

dopaminergic path.<br />

(2) Low level Pb exposure is associated with D1 subsensitivity.<br />

15–25<br />

30–50 µg/dL<br />

Pb exposures attenuated the decrements in rates produced by the two D1 agonists SKF38393 and SKF82958, and at 150 ppm, Pb exposure altered the<br />

rate change associated with the low dose (0.033 mg/kg) <strong>of</strong> quinpirole.<br />

Cory-Slechta<br />

et al. (1996a,c)<br />

Cory-Slechta<br />

et al. (1996b)<br />

35.0 µg/dL Post-washout decrease in sensitivity to MK-801. Cory-Slechta<br />

(1997)<br />

49.1 µg/dL Increases FI schedule-controlled behavior in nucleus accumbens. Cory-Slechta<br />

et al. (1998)<br />

49.1 µg/dL Both DA and EEDQ, microinjected into the dorsomedial striatum, caused<br />

increases or decreases in FI response rates, which depended on baseline FI<br />

overall rates.<br />

Cory-Slechta<br />

et al. (2002)


AX5-25<br />

Subject<br />

Hamster,<br />

Golden<br />

Rat, Wistar,<br />

female<br />

BK:W mice,<br />

male and<br />

female<br />

BK:W mice,<br />

male and<br />

female<br />

Monkey,<br />

rhesus,<br />

4 yrs<br />

Exposure<br />

Protocol<br />

100 ppm Pb(Ac) 2<br />

GD8–PND 42<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

8, 16, or 24 mg/mL Pb(Ac) 2<br />

during pregnancy, pregnancy<br />

and lactation, or lactation.<br />

0.13% Pb(Ac) 2 chronically<br />

started be<strong>for</strong>e breeding<br />

0.25% Pb(Ac) 2 chronically<br />

started be<strong>for</strong>e<br />

breeding<br />

10 mg/kg/d pulses (2) and<br />

chronic 0.7 <strong>for</strong> first yr <strong>of</strong> life<br />

Rat, SD 350 ppm Pb(Ac) 2 from birth<br />

until weaning<br />

Rat LE,<br />

PND 53<br />

300 or 600 ppm Pb(Ac) 2 during<br />

gestation and lactation or<br />

lactation only<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

PND 42:<br />

10–15 µg/d<br />

PND 19–20: Pb-exposed hamsters smaller, exhibited less play fighting.<br />

PND 45: Pb-induced increase in aggression.<br />

5.7–36.6 µg/dL PND 7: dose-dependent decrease in ultrasonic vocalization. PND 14:<br />

increased vocalization, and higher activity levels.<br />

Brain and femur:<br />

18 wks:<br />

27.6 and 998<br />

34 wk: 445 and<br />

5, 364 (M)<br />

34 wk: 787 and<br />

4, 026 (F)<br />

5 wks: 55 µg/dL<br />

first yr: ~36 yr 4:<br />


AX5-26<br />

Subject<br />

Monkey,<br />

cynomolgus,<br />

9–10 yrs <strong>of</strong> age<br />

Rat, male,<br />

adult<br />

Exposure<br />

Protocol<br />

50 or 100 µg/kg/d<br />

Pb(Ac) 2<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

500 ppm Pb(Ac) 2 in chow <strong>for</strong><br />

105 days<br />

Rat, LE 1500 ppm Pb(Ac) 2 gestation<br />

and lactation<br />

Rat, Wistar,<br />

male<br />

Rat, LE,<br />

female<br />

Rat, LE, male<br />

and female<br />

100 mg/kg/body weight by<br />

injection<br />

75 or 300 ppm Pb(Ac) 2 in<br />

water GD0 experimental use<br />

500 ppm Pb choride during<br />

lactation<br />

Rat, LE 250 ppm Pb(Ac) 2 chronically<br />

from gestation<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

15.4 and<br />

25.4 µg/dL; 10.9<br />

and 13.1 µg/dL,<br />

steady state<br />

Pb-induced impairment in the presence, but not the absence, <strong>of</strong> irrelevant cues;<br />

in the lower-dose group monkeys, impairment ended when the irrelevant<br />

stimuli became familiar.<br />

Gilbert and Rice<br />

(1987)<br />

28 µg/dL Chronic Pb exposure attenuates cocaine-induced behavioral activation. Grover et al.<br />

(1993)<br />

3.9 µg/dL at<br />

PND 50<br />

Pb + enriched environment: enhanced per<strong>for</strong>mance in water maze; increased<br />

gene expression in the hipppocampus <strong>of</strong> NMDAR subunit 1 and BDNF.<br />

Not reported Pb-induced deficits in memory component <strong>of</strong> the radial arm maze test and in<br />

retention <strong>of</strong> passive avoidance learning.<br />

Guilarte et al.<br />

(2003)<br />

Haider et al.<br />

(2005)<br />

51 µg/dL Impairment <strong>of</strong> reversal learning as an associative deficit. Hilson and Strupp<br />

(1997)<br />

42 µg/dL PND 11: no Pb-induced sex differences, effects on pup activity, and<br />

differences in pup retrieval by dams.<br />

PND 26: Pb treatment influenced all social behavior tested (i.e., investigation<br />

duration and frequency, crossover frequency, pinning) but did not change<br />

activity levels.<br />

PND 36: Pb-treated pups demonstrated increased crossover frequencies but no<br />

change in activity levels compared to controls.<br />

Hippocampal<br />

Pb levels<br />

PND 21: 1.73;<br />

PND 56: 1.02;<br />

PND 91:<br />

0.91 µg/g<br />

Pb-exposure had no effect on working memory at any age tested, but did affect<br />

reference memory (significant in females and nearly significant in males) in the<br />

PND 21 rats.<br />

Holloway and<br />

Thor (1987)<br />

Jett et al. (1997)


AX5-27<br />

Subject<br />

Exposure<br />

Protocol<br />

Rat, LE, male 750 ppm Pb(Ac) 2<br />

maternally, permanently,<br />

or postweaning only<br />

Monkey,<br />

rhesus<br />

Monkey,<br />

rhesus<br />

Monkey,<br />

rhesus<br />

Monkey,<br />

rhesus,<br />

5–6 yrs<br />

Monkey,<br />

rhesus,<br />

7–9 yrs<br />

Monkey,<br />

rhesus<br />

Monkey,<br />

rhesus<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

Pb(Ac) 2 testing first 4 wks <strong>of</strong><br />

life<br />

1 mg/kg/d Pb(Ac) 2<br />

PND 5–PND 365<br />

Pb(Ac)2 testing first 4 wks <strong>of</strong><br />

life<br />

10 mg/kg/d pulses (2) and<br />

chronic 0.7 <strong>for</strong> first yr <strong>of</strong> life<br />

10 mg/kg/d pulses (2) and<br />

chronic 0.7 <strong>for</strong> first yr <strong>of</strong> life<br />

10 mg/kg/d pulses (2) and<br />

chronic 0.7 <strong>for</strong> first yr <strong>of</strong> life<br />

350 or 600 ppm<br />

in utero<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

At PND 100<br />

1.8, 21.3, 22.8,<br />

and 26.3 µg/dL<br />

Maternal and permanent exposure: impaired water maze per<strong>for</strong>mance, with<br />

maternal exposure producing both the greatest escape latency and longest<br />

escape path length. No effects on per<strong>for</strong>mance in the postweaning exposure<br />

groups.<br />

Kuhlmann et al.<br />

(1997)<br />

35 µg/dL Pb-induced greater agitation, climbing, fear, and exploration <strong>of</strong> the periphery. Lasky and Laughlin<br />

(2001)<br />

First yr<br />

~70 µg/dL<br />

16-mo PE:<br />

~35 µg/dL<br />

First yr: Pb-induced disruption <strong>of</strong> social play, and increases in both selfstimulation<br />

and fearful behavior were observed. 16 mo: continued<br />

disruption.<br />

35 µg/dL Few differences between control and Pb-exposed monkeys were seen; less<br />

stability in SNAP per<strong>for</strong>mance.<br />

250–300 µg/dL<br />

peak<br />

80 <strong>for</strong> rest <strong>of</strong> yr<br />

1–4 wk:<br />

63 µg/dL<br />

5–6 wk: 174<br />

4 yrs: 4<br />

7 yrs: 2<br />

wk 5: 56 during;<br />

remainder <strong>of</strong> first<br />

6 mo: 33–<br />

43 µg/dL<br />

Pb-induced deficits occurred most commonly with short intertrial delays;<br />

lose-shift errors, possibly due to perseveration.<br />

Chronic L-dopa ameliorated the Pb-induced DSA deficits, which returned<br />

following cessation <strong>of</strong> L-dopa administration: implicates DA mechanisms in<br />

these impairments.<br />

First 6 wks: Pb-induced lowered muscle tonus and greater agitation, no<br />

effects on sensorimotor measures. PND 14: no Pb-related effects on object<br />

permanence task.<br />

2 mo: Pb-induced decreased visual attentiveness in visual exploration task.<br />

50 and 110 µg/dL At age 12 to 15 mo, the high-dose group exhibited deficits in simple<br />

discrimination learning: both groups showed impairments in the more<br />

complex learning set <strong>for</strong>mation trials; activity at 12–15 mo showed no<br />

Pb-related effects.<br />

Laughlin et al.<br />

(1991)<br />

Laughlin et al.<br />

(1999)<br />

Levin and Bowman<br />

(1986)<br />

Levin et al. (1987)<br />

Levin et al. (1988)<br />

Lilienthal et al.<br />

(1986)


AX5-28<br />

Subject<br />

Rat, SD, male,<br />

PND 60<br />

Exposure<br />

Protocol<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

8 or 16 mg Pb(Ac) 2 6.8 µg/dL Long-lasting changes in drug responsiveness to cocaine and related drugs. Miller et al. (2001)<br />

Rat, Wistar 500 ppm Pb(Ac) 2 through<br />

pregnancy and lactation<br />

Rat, LE 75 or 300 ppm Pb(Ac) 2<br />

continuously<br />

Rat LE,<br />

PND 53<br />

Rat, Wistar<br />

tested at<br />

PND 100 and<br />

PND 142<br />

Rat, Wistar,<br />

female<br />

Rat, Wistar,<br />

female<br />

Rat, Wistar,<br />

PND 80<br />

300 or 600 ppm during<br />

gestation or gestation and<br />

lactation<br />

750 ppm though PND 16<br />

maternal exposure or<br />

chronically<br />

750 ppm Pb(Ac) 2<br />

750 ppm Pb(Ac) 2<br />

400 mg/L Pb Cl 2 in dam’s<br />

water PND 1–30<br />

41.24 µg/dL<br />

(dams),<br />

21.24 µg/dL<br />

(PND 23),<br />


AX5-29<br />

Subject<br />

Rat, SD, male,<br />

adult<br />

Rat, SD,<br />

PND 120<br />

Rat, SD,<br />

PND 70<br />

Rabbit, Dutch<br />

Belted, male<br />

Monkey,<br />

squirrel<br />

Monkey,<br />

squirrel<br />

Monkey,<br />

cynomolgus<br />

Monkey,<br />

cynomolgus<br />

Monkey,<br />

cynomolgus,<br />

7–8 yr<br />

Monkey,<br />

cynomolgus,<br />

7–8 yr<br />

Exposure<br />

Protocol<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

500 ppm Pb(Ac) 2 28.91 µg/dL Decreases sensitization to the locomotor-stimulating effects <strong>of</strong> cocaine. Nation et al. (1996)<br />

16 mg Pb(Ac) 2 via gavage<br />

30 days pre-pregnancy to<br />

PND 21<br />

16 mg Pb(Ac) 2 via gavage<br />

30 days pre-pregnancy to<br />

PND 21<br />

Pb(Ac) 2<br />

Mother's blood Pb from<br />

gestation week 5–birth<br />

38.0 µg/dL Self-administering rats prenatally exposed to Pb demonstrate and increased<br />

sensitivity to the relapse phase <strong>of</strong> cocaine abuse.<br />

Nation et al. (2003)<br />

53.24 µg/dL Increased sensitivity to cocaine in rats perinatally exposed to Pb. Nation et al. (2004)<br />

20, 40, and<br />

80 µg/dL<br />

In utero exposure 21–70 µg/dL<br />

maternal<br />

2 mg/kg/d <strong>of</strong> Pb(Ac) 2<br />

continuously<br />

50 or 100 µg/kg/d Pb(Ac)2<br />

chronically beginning<br />

at PND 1<br />

Exposed males mated with nonexposed females. Offspring at PND 25<br />

showed Pb-induced effects on exploratory behavior.<br />

21–79 µg/dL Reduced sensitivity to changes in rein<strong>for</strong>cement contingencies during<br />

behavioral transitions and in steady state.<br />

115 µg/dL at<br />

PND 100<br />

33 µg/dL by<br />

PND 270<br />

PND 100: 15.4<br />

and 25.4<br />

PND 300: 10.9<br />

and 13.1 µg/dL<br />

Pb-induced increase in the number <strong>of</strong> responses that failed to adequately<br />

displace the bar in the FR schedule and possible subtle motor impairments.<br />

At PND 60: Pb-induced increased mean FR pause times, and, decreased FI<br />

pause times. At 3 yrs <strong>of</strong> age: Pb-induced increased FI run rate, pause time,<br />

and index <strong>of</strong> curvature. At both ages, Pb-induced increased variability <strong>of</strong><br />

per<strong>for</strong>mance.<br />

Delayed alternation at 7–8 yrs <strong>of</strong> age: Pb-induced impairment <strong>of</strong> initial<br />

acquisition <strong>of</strong> tasks; longer delays between alternations resulted in poorer<br />

per<strong>for</strong>mance and perseverative behavior, sometimes lasting <strong>for</strong> hours.<br />

Nelson et al. (1997)<br />

Newland et al.<br />

(1994)<br />

Newland et al.<br />

(1996)<br />

Rice (1988a)<br />

Rice and Karpinski<br />

(1988)<br />

1500 µg/kg/d Pb(Ac)2 36 µg/dL Pb exposure in infancy only impaired spatial discrimination reversal tasks. Rice (1990)<br />

1500 µg/kg/d Pb(Ac) 2<br />

continuously from birth,<br />

during infancy only, or<br />

beginning after infancy<br />

36 µg/dL All Pb-treated groups: same impairments <strong>of</strong> initial acquisition, indiscriminate<br />

responding, greater impairment with longer delays, and preseverative<br />

responses.<br />

Rice and Gilbert<br />

(1990b)


AX5-30<br />

Subject<br />

Monkey,<br />

cynomolgus,<br />

5–6 yr<br />

Monkey,<br />

cynomolgus,<br />

3 or 7 yr<br />

Monkey,<br />

cynomolgus,<br />

8–9 yr<br />

Monkey,<br />

cynomolgus,<br />

0.5 or 3 yr<br />

Exposure<br />

Protocol<br />

Table AX5-3.4 (cont’d). Summary <strong>of</strong> Key Studies on Neurobehavioral Toxicity<br />

1500 µg/kg/d Pb(Ac)2<br />

continuously from birth, during<br />

infancy only, or beginning after<br />

infancy<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

36 µg/dL Post-infancy exposure impairs nonspatial discrimination reversal while<br />

exposure during infancy exacerbates the effect.<br />

1500 µg/kg/d Pb(Ac) 2 36 µg/dL Pb exposure during different developmental periods produce different effects<br />

on F1 per<strong>for</strong>mance in juveniles versus adults.<br />

1500 µg/kg/d Pb(Ac) 2<br />

continuously from birth, during<br />

infancy only, or beginning after<br />

infancy<br />

36 µg/dL Pb-treated monkeys in all three exposure groups learned more slowly, with<br />

less impairment in infancy-only exposures, and showed perseverative<br />

behavior.<br />

2000 µg/kg/d Pb(Ac)2 115 µg/dL Decreased interresponse times and a greater ratio <strong>of</strong> responses per<br />

rein<strong>for</strong>cement on the differential rein<strong>for</strong>cement <strong>of</strong> low rate schedule.<br />

Rat, adult 16 mg Pb(Ac) 2<br />

via gavage 30 days pre-<br />

pregnancy to PND 21<br />

Rat 0.5, 2.0, or 4.0 mM Pb(Ac) 2 in<br />

drinking water<br />

83.2 µg/dL Developmental Pb exposure results in enhanced acquisition <strong>of</strong> cocaine selfadministration.<br />

11–50 µg/dL Pb-induced decreased retention in shuttle avoidance task. Pb-associated<br />

increase in locomotor activity.<br />

Rat, F344 ~42 µg/dL Pb-induced better per<strong>for</strong>mance using extra-maze spatial cues; Pb-treated rats<br />

spent less time on the periphery <strong>of</strong> the maze.<br />

Rat, LE, male 0.2% Pb(Ac) 2 from<br />

PND 25 until testing at<br />

PND 100<br />

Rat, Wistar 750 ppm Pb(Ac)2<br />

gestation and lactation<br />

Rat, Wistar 0.03%, 0.09%,<br />

or 0.27%<br />

Pb(Ac)2<br />

gestationally<br />

~30 in Pb Pb-exposure + isolation: spatial learning deficits. Pb-exposure + enrichment:<br />

per<strong>for</strong>med better than the isolated Pb group. Pb-induced decreases in<br />

hippocampal levels <strong>of</strong> BDNF, NGF-β, NT-3, and basic FGF.<br />

PND 30:<br />

25 µg/dL<br />

PND 90:<br />

0.113 µg/dL<br />

~30, ~33, and<br />

~42 µg/dL at<br />

PND 0, tested at<br />

PND 49<br />

At PND 30 and 90: no Pb-associated changes in elevated maze behavior.<br />

PND 30: decreased freezing, increased ambulation, and increased grooming.<br />

PND 90: Pb-induced decreased freezing and increased ambulation.<br />

Offspring <strong>of</strong> Pb-treated females mated with nonexposed males.<br />

F2 generation at PND 30 and 90: increased ambulation and decreased<br />

grooming.<br />

Male <strong>of</strong>fspring: all three doses impaired memory retrieval. Female <strong>of</strong>fspring:<br />

only the low dose affected memory retrieval. Motor per<strong>for</strong>mance and vision<br />

were not affected by Pb.<br />

Rice and Gilbert<br />

(1990a)<br />

Rice (1992a)<br />

Rice (1992c)<br />

Rice (1992b)<br />

Rocha et al. (2005)<br />

Rodrigues et al.<br />

(1996a)<br />

Salinas and Huff<br />

(2002)<br />

Schneider et al.<br />

(2001)<br />

Trombini et al.<br />

(2001)<br />

Yang et al. (2003)


AX5-31<br />

Subject Exposure Protocol<br />

Rat, PND 110 Water—0.2% Pb(Ac) 2 from<br />

GD 16-PND 21 or use<br />

Table AX5-3.5. Summary <strong>of</strong> Key Studies on Cell Morphology and Metal Disposition<br />

Rat C6 glioma cells and human<br />

astrocytoma cells<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

C Reduction in hippocampal neurogenesis with no spatial learning<br />

impairments.<br />

5–10 µM Pb(Ac) 2<br />

Directly targets GRP78 and induces its compartmentalized<br />

redistribution. GRP78 plays a protective role in Pb neurotoxicity.<br />

Rat pup astroglial cell culture 10 µM Pb(Ac)2 Oxidative stress in astroglia results from Pb impairment <strong>of</strong> the Cu<br />

transporter Atpase (Atp7a).<br />

Gilbert et al. (2005)<br />

Qian et al. (2005a)<br />

Qian et al. (2005b)<br />

Rat, PND 60 1500 ppm Pb(Ac) 2 <strong>for</strong> 30–35 days 20.0 µg/dL Significant deleterious effects on progenitor cell proliferation. Schneider et al.<br />

(2005)<br />

Rat,<br />

Cultured neurospheres 0.1–100 µM Differentially affects proliferation and differentiation <strong>of</strong> embryonic<br />

embryos<br />

Pb(Ac)2 neural stem cells originating from different brain regions.<br />

Young rat PND 0–20 = 600 µg/dL<br />

131.3 µg/dL Blood Pb during succimer chelation are not an immediate indicator<br />

PND 20–40 = 20–60 µg/dL<br />

<strong>of</strong> brain. Brain Pb values are slower to respond even though blood<br />

Pb is normal.<br />

Cultured oligodendrite progenitor<br />

cells—PND 2<br />

Cultured oligodendrite progenitor<br />

cells—PND 2<br />

1 µM Pb(Ac) 2<br />

0.1–100 µM<br />

Pb(Ac)2<br />

Cultured cerebellar granule neurons 5–50 µM Pb(NO 3) 2<br />

or Pb(ClO 4) 2<br />

Pb inhibition <strong>of</strong> proliferation and differentiation <strong>of</strong> oligodendrocyte<br />

cells requires PKC.<br />

Huang and Schneider<br />

(2004)<br />

Stangle et al. (2004)<br />

Deng and Poretz<br />

(2002)<br />

Interferes with maturation <strong>of</strong> oligodendrocyte progenitor cells. Deng et al. (2001)<br />

Specific transport systems carry Pb into neurons. Mazzolini et al.<br />

(2001)<br />

Rat Cultured C6 glioma cells 1 µM Pb(Ac) 2 Induces GRP78 protein expression and GRP78 is a strong Pb<br />

chelator.<br />

Human,<br />

1–4 yr<br />

Rat and human Cultured rat astroglial,<br />

human neuroblastoma<br />

Cultured GH3, C6, and HEK293<br />

cells<br />

1 µM Pb(Ac)2<br />

1–10 µM Pb(NO3) 2<br />

Half-life <strong>of</strong> blood Pb was dependent upon exposure duration,<br />

ranging 10–38 mo.<br />

Immature astroglia vs. neuronal cells are most likely to bind Pb in<br />

the brain.<br />

Review paper addressing Pb-binding proteins in the brain and<br />

kidney.<br />

Cellular uptake <strong>of</strong> Pb is activated by depletion <strong>of</strong> intracellular<br />

calcium.<br />

Qian et al. (2000)<br />

Manton et al. (2000)<br />

Lindahl et al. (1999)<br />

Fowler (1998)<br />

Kerper and Hinkle<br />

(1997)<br />

Rat 2 g/l Pb(Ac)2 in weanlings <strong>for</strong> 3 mo 39 µg/dL Chronic low Pb levels induces blood brain barrier dysfunction. Strużyńska et al.<br />

(1997)


AX5-32<br />

Subject Exposure Protocol<br />

Table AX5-3.5 (cont’d). Summary <strong>of</strong> Key Studies on Cell Morphology and Metal Disposition<br />

Rat 50 or 250 µg/mL Pb(Ac) 2 <strong>for</strong> 30, 60,<br />

or 90 days<br />

Frog<br />

tadpoles<br />

Elvax implantation <strong>for</strong> 6 wks 10 !10 to 10 !6 M<br />

Pb Cl 2<br />

Peak Blood Pb<br />

or [Pb] Used Observed Effects Reference<br />

48.9 µg/dL Low dose, long-term exposure significantly decreases cerebral<br />

spinal fluid concentrations <strong>of</strong> TTR.<br />

Stunted neuronal growth from low Pb levels are reversible with<br />

chelator.<br />

Zheng et al. (1996)<br />

Cline et al. (1996)<br />

Rat Cultured hippocampal neurons 100 nM Pb Cl 2 Possible neurite development inhibition via hyperphosphorylation. Kern and Audesirk<br />

(1995)<br />

Human Pb-binding proteins isolated from<br />

cortex<br />

Rats<br />

PND 7–60<br />

100–2000 ppm Pb(Ac) 2 in water <strong>for</strong><br />

adult rats<br />

Rat, adult Radiolabeled Pb perfused across<br />

whole brain<br />

10–2000 nM Characterizes two cytosolic Pb-binding proteins-thymosin beta 4<br />

Pb(Ac)2 and an unidentified protein.<br />

72.5 µg/dL Elimination half-life <strong>of</strong> Pb from all regions <strong>of</strong> the brain was about<br />

20 days. There was no evidence <strong>of</strong> selective regional accumulation<br />

<strong>of</strong> Pb.<br />

9.7 mL/100 g Review paper examining the passage <strong>of</strong> Pb across the blood-brain<br />

barrier. Suggests it is actively transported via Ca-ATP pump.<br />

Review paper indicating that Pb either structurally alters nuclear<br />

protein p32/6.3 or inhibits a protease <strong>for</strong> which it is a substrate.<br />

Review paper discussing Pb removal from bone; the half-life <strong>of</strong> Pb<br />

in bone is about 20 yr while in blood it is 1 mo.<br />

Quintanilla-Vega<br />

et al. (1995)<br />

Widzowski and<br />

Cory-Slechta (1994)<br />

Bradbury and Deane<br />

(1993)<br />

Shelton et al. (1993)<br />

Wedeen (1992)<br />

Rat, adult Radiolabeled albumin C Discovered that albumin rarely enters brain from blood. Bradbury et al.<br />

(1991)<br />

Guinea pig,<br />

chicken, and<br />

rat<br />

Mouse neuroblastoma<br />

2a cell line<br />

Dog and rat Mouse neuroblastoma<br />

2a cell line<br />

Adult rat Pb binding protein <strong>of</strong> kidney<br />

and brain<br />

Rat Perfusion <strong>of</strong> 0.5 MBq <strong>of</strong> Pb-203<br />

isotope <strong>for</strong> 0.5–4 h<br />

C Results indicate a positive correlation between p32/6.3 levels and<br />

neuronal maturation.<br />

50–100 µM Pb Examined the relationship between Pb and nuclear protein p32/6.3<br />

and its abundance in intranuclear inclusion bodies.<br />

0.1–1.6 µM Attenuation <strong>of</strong> Pb inhibition <strong>of</strong> ALAD involves sequestration <strong>of</strong> Pb<br />

and a donation <strong>of</strong> zinc to the enzyme.<br />

615 µg/dL Injections <strong>of</strong> Pb-203 showed a linear uptake into three regions <strong>of</strong><br />

the brain, suggesting that the blood-brain barrier is rate-limiting.<br />

Human C 160 µg/100 mL Blood Pb half-life is affected by duration <strong>of</strong> exposure, age, and<br />

length <strong>of</strong> follow-up.<br />

Klann and Shelton<br />

(1990)<br />

Klann and Shelton<br />

(1989)<br />

Goering et al. (1986)<br />

Bradbury and Deane<br />

(1986)<br />

Hryhorczuk et al.<br />

(1985)<br />

Human C >60 µg/dL Blood Pb half-life is dependent upon the length <strong>of</strong> exposure. O’Flaherty et al.<br />

(1982)


AX5-33<br />

Table AX5-3.6. Key Studies Evaluating Chelation <strong>of</strong> Pb in Brain<br />

Subject Exposure Protocol Chelator Observed Effects Reference<br />

Rat, male, LE,<br />

PND 21<br />

Rat, male, LE,<br />

PND 21<br />

Rat, female,<br />

Wistar<br />

Group 1: 50 ppm Pb acetate in<br />

drinking water from PND 21<br />

<strong>for</strong> 3–4 mo, after which they<br />

were given i.p. injections <strong>of</strong><br />

75 or 150 mg/kg CaEDTA <strong>for</strong><br />

either 1, 2, 3, 4, or 5 days.<br />

Group 2: 25 or 500 ppm Pb<br />

acetate followed by a single<br />

injection <strong>of</strong> either 75 or<br />

150 mg/kg CaEDTA. Twentyfour<br />

hour urine samples were<br />

collected following CaEDTA<br />

injections.<br />

50 ppm Pb acetate from<br />

weaning until testing 3–4 mo<br />

later. The rats received either<br />

25 or 50 mg/kg DMSA <strong>for</strong> 1, 2,<br />

3, 4, or 5 days and tissues were<br />

evaluated 24 h following the<br />

last injection.<br />

Given 206 Pb-enriched drinking<br />

water at 210 ng Pb/mL <strong>for</strong><br />

36 h. Following an overnight<br />

fast, the rats were injected with<br />

one 0.25 mL i.p. injection <strong>of</strong><br />

0.11 mmol/kg DMSA. Pb<br />

levels in blood, kidney, brain,<br />

and tibia assessed 24 h later.<br />

CaEDTA Group 1: Blood Pb declined after the first CaEDTA injection, but did not drop<br />

further with subsequent CaEDTA and never dropped below control levels<br />

(5 µg/dL). Pb levels in urine increased similarly with both doses <strong>of</strong> CaEDTA.<br />

Pb was found to be mobilized from both bone and kidney and initially<br />

redistributed to brain and liver. Subsequent CaEDTA injections caused<br />

declines in brain and liver Pb levels, but no net loss <strong>of</strong> Pb.<br />

Group 2: a single injection <strong>of</strong> 150 mg/kg CaEDTA caused marked elevation<br />

<strong>of</strong> brain Pb, which called into question use <strong>of</strong> injections <strong>of</strong> CaEDTA in<br />

clinical diagnostic procedures.<br />

DMSA Blood Pb was decreased by DMSA dose-dependently, with levels dropping to<br />


AX5-34<br />

Table AX5-3.6 (cont’d). Key Studies Evaluating Chelation <strong>of</strong> Pb in Brain<br />

Subject Exposure Protocol Chelator Observed Effects Reference<br />

Rat, female,<br />

Albino<br />

Rat, male, SD<br />

rats at 6–7 wks<br />

Rat, male,<br />

Wistar<br />

100 ppm Pb acetate in drinking<br />

water <strong>for</strong> 4 wks. During the last 2<br />

days <strong>of</strong> that exposure, the rats were<br />

administered two i.p. injections <strong>of</strong> 1<br />

µg stable 204 Pb tracer. Animals then<br />

received 1 to 5 consecutive days <strong>of</strong><br />

150 mg/kg CaEDTA ; assayed 24 h<br />

following the last injection.<br />

Chelation with ongoing Pb<br />

exposure; blood Pb were ~45 µg/dL;<br />

550 ppm Pb acetate in drinking<br />

water <strong>for</strong> 35 days.<br />

Group 1: continued on Pb only <strong>for</strong><br />

21 days.<br />

Group 2: received continued Pb<br />

plus oral DMSA at 16, 32, 120, or<br />

240 mg/kg/d <strong>for</strong> 21 days.<br />

Group 3: discontinued on Pb after<br />

the first 35 days and received oral<br />

DMSA (16, 32, or 240 mg/kg/d).<br />

Dosed with 1000 ppm Pb in<br />

drinking water <strong>for</strong> 4 mo, then treated<br />

<strong>for</strong> 5 days with: saline; 25 mg/kg<br />

DMSA orally, twice daily; 75 mg/kg<br />

CaEDTA i.p. once daily; or<br />

25 mg/kg DMSA twice daily plus<br />

75 mg/kg CaEDTA i.p. once daily.<br />

Blood Pb resulting from these<br />

treatments were 46, 22, 28, and 13<br />

µg/dL, respectively and brain Pb<br />

levels were 49, 38, 26, and 22 µg/g,<br />

respectively.<br />

CaEDTA No redistribution <strong>of</strong> endogenous Pb into the brain following one<br />

CaEDTA dose, no measurable reduction in brain or bone Pb levels, and<br />

reductions in both kidney and blood Pb levels. Additionally, over the<br />

first day <strong>of</strong> treatment, CaEDTA reduced the 204 Pb tracer more<br />

effectively than the Pb from chronic exposure, indicating greater<br />

biologically availability <strong>of</strong> Pb from recent exposures.<br />

DMSA DMSA treatment increased urinary Pb and decreased levels <strong>of</strong> Pb in<br />

blood, brain, bone, kidney, and liver, even with continued Pb exposure.<br />

CaEDTA and<br />

DMSA<br />

The combined treatments produced an additive response in urinary Pb<br />

elimination and elimination from blood, liver, kidney, brain, and femur.<br />

Seaton et al. (1999)<br />

Pappas et al. (1995)<br />

Flora et al. (1995)


AX5-35<br />

Table AX5-3.6 (cont’d). Key Studies Evaluating Chelation <strong>of</strong> Pb in Brain<br />

Subject Exposure Protocol Chelator Observed Effects Reference<br />

Rat, female,<br />

LE<br />

Group 1: 325 µg/mL Pb<br />

acetate maternally through<br />

weaning, and then to 30 µg/mL<br />

until PND 30. Chelation<br />

treatment consisted <strong>of</strong> 7 days <strong>of</strong><br />

30 or 60 mg/kg/d DMSA.<br />

Group 2: 325 µg/dL<br />

maternally and through<br />

PND 40 and then treated to<br />

DMSA <strong>for</strong> 7 or 21 days.<br />

Rat, LE Exposed gestationally to<br />

600 µg/mL Pb acetate, then<br />

split into high and low dose<br />

groups.<br />

Low dose group: 20 µg/mL<br />

from PND 21–28, followed by<br />

30 µg/mL from PND 29–40.<br />

High dose group: 40 µg/mL<br />

from PND 21–28, followed by<br />

60 µg/mL from PND 29–40.<br />

DMSA treatment consisted <strong>of</strong><br />

50 mg/kg/d <strong>for</strong> 1 wk, then<br />

25 mg/kg/d <strong>for</strong> 2 wks. Rats<br />

received either 1 or<br />

2 treatments at PND 40 or<br />

40 and 70.<br />

DMSA Seven days <strong>of</strong> DMSA effectively removed Pb from both blood and brain.<br />

Treatment beyond 7 days further reduced brain Pb, but not blood Pb.<br />

Reductions in Pb were greater in the second group, which the authors attribute<br />

to the higher exposures used. The authors also hypothesize that DMSAmediated<br />

reduction in blood Pb are a poor indicator <strong>of</strong> reductions in brain Pb.<br />

DMSA One treatment lowered both blood Pb and brain Pb, but the brain reductions<br />

lagged the blood reductions both temporally and in magnitude. Following the<br />

second DMSA treatment, they observed a rebound in blood, but not brain Pb<br />

levels.<br />

Smith et al. (1998)<br />

Stangle et al. (2004)


AX5-36<br />

Table AX5-3.6 (cont’d). Key Studies Evaluating Chelation <strong>of</strong> Pb in Brain<br />

Subject Exposure Protocol Chelator Observed Effects Reference<br />

Monkey,<br />

Rhesus,<br />

11-yr-old with<br />

history <strong>of</strong><br />

testing <strong>for</strong><br />

effects <strong>of</strong><br />

housing and<br />

rearing and<br />

which were<br />

used in drug<br />

challenge<br />

studies, were<br />

used after at<br />

least 1.5 yrs<br />

had elapsed<br />

since the last<br />

testing<br />

Rat, male, LE,<br />

PND 55<br />

Rat, male,<br />

F344, 7-wkold<br />

male<br />

~50 mg/kg/d Pb acetate, and<br />

then doses were adjusted to<br />

produce a target blood Pb <strong>of</strong><br />

35–40 µg/dL. Following 5 wks<br />

<strong>of</strong> Pb exposure, the monkeys<br />

were administered 204 Pb tracer<br />

starting 4 days be<strong>for</strong>e chelation.<br />

DMSA was administered <strong>for</strong><br />

5 days at 30 mg/kg/d, followed<br />

by 14 days at 20 mg/kg/d.<br />

At PND 55, rats were started on<br />

an FI schedule, where a Pbinduced<br />

increase in<br />

interresponse time was<br />

observed. Pb exposure was<br />

then terminated and daily<br />

injections <strong>of</strong> 75 or 150 mg/kg<br />

CaEDTA were given <strong>for</strong><br />

5 consecutive days.<br />

150 or 2000 ppm Pb <strong>for</strong><br />

21 days, then distilled water <strong>for</strong><br />

the next 21 days. Blood Pb<br />

peaked at 37 and 82 µg/dL,<br />

respectively. Chelation:<br />

50 mg/kg by oral gavage,<br />

3 times a week <strong>for</strong> up to<br />

21 days; reduced blood Pb to<br />

22 and 56 µg/dL, respectively.<br />

DMSA Brain levels <strong>of</strong> Pb and tracer, measured in prefrontal cortex, hippocampus, and<br />

striatum, were not different from controls, indicating that DMSA was not<br />

effective in reducing brain Pb levels. They also found a poor correlation<br />

between brain and blood Pb levels.<br />

CaEDTA Chelation treatment failed to reverse the learning deficits in Pb-exposed<br />

animals and further increased the proportion <strong>of</strong> short interresponse times. The<br />

authors suggest that this effect may be due to the CaEDTA-mediated<br />

redistribution <strong>of</strong> Pb from bone to brain.<br />

DMSA Pb-induced increase in rearing behavior was observed. DMSA reduced the<br />

Pb-induced effects on activity. Levels <strong>of</strong> brain glial fibrillary acidic protein<br />

(GFAP) were also assessed in these animals. A Pb-induced dose-dependent<br />

increase in GFAP was observed in hippocampus, cortex, and cerebellum,<br />

which was reversed by DMSA treatment.<br />

Cremin et al. (1999)<br />

Cory-Slechta and<br />

Weiss (1989)<br />

Gong and Evans<br />

(1997)


ANNEX TABLES AX5-4<br />

AX5-37


AX5-38<br />

Citation<br />

Al-Hakkak<br />

et al. (1988)<br />

Appleton<br />

(1991)<br />

Bataineh<br />

et al. (1998)<br />

Berry et al.<br />

(2002)<br />

Bogden et al.<br />

(1995)<br />

Camoratto<br />

et al. (1993)<br />

Corpas<br />

(2002a)<br />

Corpas<br />

(2002b)<br />

Table AX5-4.1. Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Mouse/BALB/c,<br />

weaning<br />

Rat/Long-Evans<br />

hooded, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, 21 days<br />

old<br />

Rat/Sprague-<br />

Dawley, 12 wks<br />

old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

0, 25, 50 mg Pb monoxide<br />

alloy/kg in chow <strong>for</strong> 35–<br />

70 days<br />

Pb acetate single dose by i.v. at<br />

30 mg/kg<br />

1000 ppm Pb acetate in<br />

drinking water <strong>for</strong> 12 wks<br />

Pb nitrate (1000 ppm Pb)<br />

in drinking water <strong>for</strong> 6 wks<br />

250 mg/L <strong>of</strong> Pb acetate in<br />

drinking water from GD 1 until<br />

after 1 wk after weaning<br />

0.02% Pb nitrate in drinking<br />

water from gestation day 5 <strong>of</strong><br />

dams until PND 4 <strong>of</strong> <strong>of</strong>fspring<br />

Rat/Wistar, adult Pb acetate 0 or 300 mg/L in<br />

drinking water during gestation<br />

and lactation<br />

Rat/Albino<br />

(NOS), adult<br />

Pb acetate 0 or 300 mg/L in<br />

drinking water during gestation<br />

and lactation<br />

Reduced number <strong>of</strong> spermatogenia and spermatocytes in the 50 mg group after 70 days;<br />

reduced number <strong>of</strong> implantations after mating (after 35 days exposure).<br />

Increase in serum calcium and phosphorous; SEM analysis revealed ‘Pb line’ in tooth<br />

that was composed <strong>of</strong> hypomineralized interglobular dentine.<br />

Fertility was reduced; total number <strong>of</strong> resorptions was increased in female rats<br />

impregnated by males.<br />

Mean plasma growth hormone levels decreased by 44.6%; reduced mean growth<br />

hormone amplitude by 37.5%, mean nadir concentration by 60%, and growth hormone<br />

peak area by 35%; findings are consistent with decreased hypothalamic growth<br />

hormone-releasing factor secretion or reduced somatotrope responsiveness; exogenous<br />

growth hormone in Pb-treated and control rats, this response was blunted by the Pb<br />

treatment; plasma IGF1 concentration was not significantly affected by Pb treatment.<br />

Dam and pup hemoglobin concentrations, hematocrit, and body weights and lengths<br />

were reduced.<br />

Female pups exposed to Pb beginning in utero were smaller, no corresponding effect in<br />

males; pituitary responsiveness to a hypothalamic stimulus.<br />

Alterations in hepatic system <strong>of</strong> neonates (PND 12) and pups (PND 21); reductions in<br />

hemoglobin, iron, alkaline and acid phosphatase levels, and hepatic glycogen, and<br />

elevated blood glucose.<br />

Effects energy metabolism; decrease in testis and seminal vesicle weights, and an<br />

increase in DNA and RNA levels on PN day 21; protein was significantly decreased,<br />

alkaline and acid phosphatase levels <strong>of</strong> the gonads were reduced; reduction <strong>of</strong> the<br />

thickness <strong>of</strong> the epithelium and seminiferous tubule diameter.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not reported<br />

PbB not reported<br />

PbB not reported<br />

PbB 37.40 ± 3.60 µg/dL<br />

PbB


AX5-39<br />

Citation<br />

Cory-Slechta<br />

et al. (2004) †<br />

Dey et al.<br />

(2001)<br />

Flora and<br />

Tandon (1987)<br />

Fox et al.<br />

(1991a)<br />

Table AX5-4.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Rat/Long-Evans,<br />

adult<br />

Mouse/Albino<br />

(NOS), ~100 g<br />

Rat/Albino<br />

(NOS), adult<br />

Rat/Long-Evans<br />

hooded, adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

Pb acetate in drinking water<br />

(150 ppm); 2 mo be<strong>for</strong>e<br />

breeding until the end <strong>of</strong><br />

lactation<br />

14 rats no maternal stress Pb<br />

exposure, 15 rats no maternal<br />

stress with Pb exposure, 18 rats<br />

maternal stress without Pb<br />

exposure, 23 rats maternal<br />

stress and Pb exposure<br />

Pb citrate 5 µg/kg-d p.o. from<br />

early pregnancy (NOS) until<br />

birth<br />

Pb nitrate dissolved in water 2–<br />

20 mg/kg-d i.v. on day 9, 10,<br />

11 <strong>of</strong> gestation; 6 rats in each<br />

group (0, 5, 10, 20, 40 mg/kg<br />

Pb)<br />

Lactation exposure via dams<br />

exposed to 0.02 or 0.2% Pb in<br />

drinking water from PND 1<br />

through weaning (PND 21)<br />

8 female pups per litter<br />

(number <strong>of</strong> litter unspecified)<br />

control pups, 8 pups <strong>for</strong> litter<br />

(number <strong>of</strong> litter unspecified)<br />

low level exposure pups,<br />

8 pups per litter (number <strong>of</strong><br />

litter unspecified) moderate<br />

level exposure pups<br />

Pb alone (in male) (p < 0.05) and Pb plus stress (in females) (p < 0.05) permanently<br />

elevated corticosterene levels in <strong>of</strong>fspring.<br />

Per<strong>for</strong>ations, tissue damage, cell de<strong>for</strong>mity, disordered organization <strong>of</strong> collagen bundles<br />

found in <strong>of</strong>fspring; reduction in the symmetry <strong>of</strong> sulphate group <strong>of</strong> skin pups <strong>of</strong> mice<br />

exposed to Pb citrate (5 µg/kg-d) throughout gestation exhibited a variety <strong>of</strong> skin<br />

anomalies, including per<strong>for</strong>ations, tissue damage, cell de<strong>for</strong>mity, and disordered<br />

collagen bundles Pb was found to affect initial genomic expression in embryos fathered<br />

by male rats.<br />

Dose-dependant increase in external mal<strong>for</strong>mations at all doses (p < 0.001), particularly<br />

tail defects; dose dependant decrease in number <strong>of</strong> live births at 20 and 400 mg/kg<br />

(p < 0.001); dose-dependent increase in number <strong>of</strong> resorptions per dam at #10 mg/kg<br />

(p < 0.01).<br />

Long-term, dose-dependent decreases retinal Na/K ATPase activity in the female<br />

<strong>of</strong>fspring (only female pups were used) (!11%; !26%) (p < 0.05).<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB 30–40 µg/dL<br />

PbB not reported<br />

PbB 13–45 µg/dL<br />

PbB 18.8 or 59.4 µg/dL at<br />

weaning


AX5-40<br />

Citation<br />

Fox et al.<br />

(1997) †<br />

Gandley et al.<br />

(1999)<br />

Govoni et al.<br />

(1984)<br />

Hamilton et al.<br />

(1994)<br />

Han et al.<br />

(2000)<br />

Hanna et al.<br />

(1997)<br />

Table AX5-4.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Rat/Long-Evans<br />

hooded, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley,<br />

25 days old<br />

Rat/Sprague-<br />

Dawley, 5 wks<br />

old<br />

Mouse/Swiss<br />

ICR<br />

preimplantation<br />

embryos<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

0.02 or 0.2% Pb acetate in<br />

drinking water from PND 0–<br />

PND 21; 8 female pups per<br />

litter control pups; 8 pups per<br />

litter low level exposure;<br />

8 pups per litter moderate level<br />

exposure (number <strong>of</strong> litters per<br />

dose unspecified)<br />

Male rats exposed to 25 or<br />

250 ppm acetate Pb in drinking<br />

water <strong>for</strong> at least 35 days prior<br />

to breeding<br />

2.5 mg/mL Pb acetate in<br />

drinking water from GD 16 to<br />

postnatal week 8<br />

Pb acetate in drinking water at<br />

250, 500 or 1000 ppm; 8 wks<br />

prior to mating through GD 21<br />

250 mg/mL Pb acetate in<br />

drinking water <strong>for</strong> 5 wks<br />

followed by 4 wks no exposure<br />

(mated at end <strong>of</strong> 4-wk no<br />

exposure period)<br />

In vitro incubation <strong>of</strong> two- and<br />

four-cell embryos with 0.05–<br />

200 µM Pb acetate <strong>for</strong> 72 hr<br />

(time required <strong>for</strong> blastocyst<br />

<strong>for</strong>mation)<br />

Developmental and adult Pb exposure <strong>for</strong> 6 wks produced age and dose-dependent<br />

retinal degeneration such that rods and bipolar cells were selectively lost; at the<br />

ultrastructural level, all dying cells exhibit the classical morphological features <strong>of</strong><br />

apoptotic cell death; decrease in the number <strong>of</strong> rods was correlated with the loss <strong>of</strong><br />

rhodopsin content per eye confirming that rods were directly affected by Pb (p < 0.05);<br />

single-flash rod ERGs and cone ERGs obtained from Pb-exposed rats demonstrated that<br />

there were age- and dose-dependent decreases in the rod a-wave and b-wave sensitivity<br />

and maximum amplitudes without any effect on cones; in adult rats exposed to Pb <strong>for</strong><br />

3 wks, qualitatively similar ERG changes occurred in the absence <strong>of</strong> cell loss or<br />

decrease in rhodopsin content (p < 0.05); developmental and adult Pb exposure <strong>for</strong><br />

three and 6 wks produced age- and dose-dependent decreases in retinal cGMP<br />

phosphodiesterase (PDE) activity resulting in increased CGMP levels (p < 0.05); retinas<br />

<strong>of</strong> developing and adult rats exposed to Pb exhibit qualitatively similar rod mediated<br />

ERG alterations as well as rod and bipolar apoptotic cell death (p < 0.05); similar<br />

biochemical mechanism such as the inhibition <strong>of</strong> rod and bipolar cell cGMP PDE,<br />

varying only in degree and duration, underlies both the Pb-induced ERG rod-mediated<br />

deficits and the rod and bipolar apoptotic cell death (p < 0.05).<br />

Fertility was reduced in males with PbB in range 27–60 µg/dL, Pb was found to affect<br />

initial genomic expression in embryos fathered by male rats with blood Pb levels as low<br />

as 15–23 µg/dL; dose-dependant increases were seen in an unidentified set <strong>of</strong> proteins<br />

with a relative molecular weight <strong>of</strong> ~70 kDa.<br />

Decreased sulpiride binding in the pituitary is consistent with the elevated serum PRL<br />

concentrations previously described in Pb-exposed rats; DOPAc concentrations were<br />

reduced by 21% in Pb-treated rats.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB weanlings 19 ± 3 (low<br />

exposure) or 59 ± 8 µg/dL<br />

(moderate exposure), adult<br />

7 ± 2 µg/dL (at PND 90)<br />

PbB 27–60 µg/dL (fathers)<br />

15–23 µg/dL (<strong>of</strong>fspring)<br />

PbB 71 ± 8 µg/dL<br />

Altered growth rates; reduced early postnatal growth; decreased fetal body weight. PbB 40–100 µg/dL<br />

Pups born to Pb-exposed dams had significantly (p < 0.0001) lower mean birth weights<br />

and birth lengths.<br />

Exposure <strong>of</strong> embryos to Pb was only toxic at 200 µM, which reduced cell proliferation<br />

and blastocyst <strong>for</strong>mation.<br />

PbB 10–70 µg/dL<br />

PbB not reported


AX5-41<br />

Citation<br />

Iavicoli et al.<br />

(2003)<br />

Iavicoli et al.<br />

(2004)<br />

Lögdberg<br />

et al. (1987)<br />

Lögdberg<br />

et al. (1998)<br />

McGivern<br />

et al. (1991) †<br />

Nayak et al.<br />

(1989a)<br />

Piasek and<br />

Kostial (1991)<br />

Table AX5-4.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Mouse/Swiss,<br />

adult<br />

Mouse/Swiss,<br />

adult<br />

Monkey/<br />

Squirrel, adult<br />

Monkey/<br />

Squirrel, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Mouse/Swiss<br />

Webster, adult<br />

Rat/Wistar,<br />

10 wks old<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

Pb acetate in food (0.02, 0.06,<br />

0.11, 0.2, 2, 4, 20, 40 ppm)<br />

exposure began 1 day after<br />

mating until litter was 90 days<br />

old one litter <strong>of</strong> mice exposed<br />

to each dietary concentration<br />

Pb acetate in feed; exposure<br />

began 1 day after mating until<br />

litter was 90 days old<br />

Pb acetate p.o. exposure <strong>of</strong><br />

gravid squirrel monkeys from<br />

week 9 <strong>of</strong> gestation through<br />

PND 0<br />

Pb acetate (varying<br />

concentrations #0.1% in diet);<br />

maternal dosing from 5–<br />

8.5 wks pregnant to PND 1;<br />

11 control monkeys, 3 low-Pb<br />

exposure group (PbB<br />

24 µg/dL), 7 medium Pb group<br />

(PbB 40 µg/dL, 5 high-Pb<br />

group (PbB 56 µg/dL)<br />

0.1% Pb acetate in drinking<br />

water from GD 14 to<br />

parturition<br />

Pb nitrate dissolved in NaCl<br />

solution, administered<br />

intravenously, via caudal vein<br />

at dose levels <strong>of</strong> 100, 150,<br />

200 mg/kg; one time exposure<br />

on GD 9<br />

7500 ppm Pb acetate in<br />

drinking water <strong>for</strong> 9 wks<br />

Low-level exposure (PbB 2–13 µg/dL) reduced red cell synthesis (p < 0.05); high-level<br />

exposure (PbB 0.6–2 µg/dL) enhanced red cell synthesis (p < 0.05).<br />

In females: accelerated time to puberty at PbB 180 µg/dL<br />

Maternal PbB >300 µg/dL<br />

Offspring PbB >220 µg/dL


AX5-42<br />

Citation<br />

Pinon-<br />

Lataillade<br />

et al. (1995)<br />

Pillai and<br />

Gupta (2005)<br />

Ronis et al.<br />

(1996) †<br />

Ronis et al.<br />

(1998a) †<br />

Ronis et al.<br />

(1998b) †<br />

Table AX5-4.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Mouse/NMRI,<br />

adult<br />

Rat/Charles<br />

Foster,<br />

200–220 g<br />

Rat/Sprague-<br />

Dawley, 22,<br />

55 days or plugpositivetimeimpregnated<br />

Rat/Sprague-<br />

Dawley, various<br />

ages<br />

Rat/Sprague-<br />

Dawley, adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

0–0.5% Pb acetate in<br />

drinking water exposed to Pb<br />

during gestation until post-<br />

GD 60<br />

Subcutaneous injection <strong>of</strong><br />

0.05 mg/kg-d Pb acetate <strong>for</strong><br />

5–7 days prior to mating<br />

through PND 21<br />

0.6% Pb acetate in drinking<br />

water <strong>for</strong> various durations:<br />

PND 24–74 (pubertal<br />

exposure), PND 60–74 (post<br />

pubertal exposure); 11 males<br />

and females in pubertal<br />

exposure group (10 each in<br />

control pubertal group);<br />

6 males and females postpubertal<br />

exposure and control<br />

groups<br />

0.6% Pb acetate in drinking<br />

water ad libitum <strong>for</strong> various<br />

durations: GD 5 to PND 1,<br />

GD 5 to weaning, PND 1 to<br />

weaning<br />

3 control litters, 2 gestation<br />

exposure litters, 2 lactation<br />

exposure litters, 2 gestation<br />

and lactation exposure litters,<br />

2 postnatal litters, 2 chronic<br />

litters (4 male and 4 female<br />

pups per litter)<br />

Pb acetate in drinking water<br />

(0.05% to 0.45% w/v); dams<br />

exposed until weaning,<br />

exposure <strong>of</strong> pups which<br />

continued until PND 21, 35,<br />

55, or 85; 5 control litters<br />

(0%), 10 low-dose litters<br />

(0.05%), 8 mid-dose litters<br />

(0.15%), 9 high-dose litters<br />

(0.45%); 4 male and 4 female<br />

pups per litter<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

Pb exposure during gestation reduces litter size; reduced birth weight and growth rates. PbB 200 µg/dL.<br />

Group: pup PbB<br />

Naïve: ~6 µg/dL<br />

Control: 100 µg/dL and reached up to<br />

388 µg/dL.


AX5-43<br />

Citation<br />

Ronis et al.<br />

(1998c)<br />

Ronis et al.<br />

(2001) †<br />

Sant'Ana et al.<br />

(2001)<br />

Singh et al.<br />

(1993b)<br />

Watson et al.<br />

(1997)<br />

Table AX5-4.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley,<br />

neonate, male<br />

(100 days) and<br />

female pup<br />

Rat/Wistar,<br />

90 days old<br />

Rat/ITRC,<br />

albino (NOS),<br />

6 wks old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

Pb acetate 0.05, 0.15, or<br />

0.45% in drinking water<br />

beginning GD 5 continuing<br />

until PND 21, 35, 55, or 85;<br />

5 control litters (0%),<br />

10 low-dose litters (0.05%),<br />

8 mid-dose litters (0.15%),<br />

9 high-dose litters (0.45%);<br />

4 male and 4 female pups<br />

per litter<br />

Pb acetate in drinking water<br />

to 825 or 2475 ppm ad<br />

libitum from G'D 4 to GD 55<br />

postpartum; 1 male and<br />

female pup/litter (5 litters per<br />

group) control group, 1 male<br />

and female pup/litter (5 litters<br />

per group) 825 ppm Pb<br />

acetate group, 1 male and<br />

female pup/litter (5 litters per<br />

group) 2475 ppm Pb acetate<br />

group<br />

0.1 and 1% Pb in drinking<br />

water<br />

7 days<br />

250, 500, 1000, and 2000<br />

ppm Pb nitrate in drinking<br />

water from GD 6 to GD 14<br />

Pb in drinking water at<br />

34 ppm from weaning <strong>of</strong><br />

mothers through gestation<br />

and weaning <strong>of</strong> <strong>of</strong>fspring<br />

until birth; 6 pups control<br />

group, 6 pups experimental<br />

group<br />

Dose-responsive decrease in birth weight (p < 0.05), and crown-to-rump length<br />

(p < 0.05); dose-responsive delay in sexual maturity in male (p < 0.05) and female<br />

(p < 0.05); neonatal decrease in sex steroids (p < 0.05); pubertal decrease in<br />

testosterone (male) (p < 0.05) and E2 (female) (p < 0.05); decrease estrous cyclicity at<br />

high dose (p < 0.05).<br />

Dose-dependent decrease <strong>of</strong> the load <strong>of</strong> failure in male (p < 0.05); no difference in<br />

plasma levels <strong>of</strong> vitamin D metabolites; reduced somatic growth (p < 0.05),<br />

longitudinal bone growth (p < 0.05), and bone strength during the pubertal period<br />

(p < 0.05); sex steroid replacement did not restore skeletal parameters in Pb exposed<br />

rats; L-Dopa increased plasma IGF1 concentrations, rates <strong>of</strong> bone growth, and bone<br />

strength measures in controls while having no effect in Pb exposed groups; DO gap xray<br />

density and proximal new endostreal bone <strong>for</strong>mation were decreased in the<br />

distration gaps <strong>of</strong> the Pb-treated animals (p < 0.01); distraction initiated at 0.2 mm 30 to<br />

60 days <strong>of</strong> age.<br />

1% Pb exposure reduced <strong>of</strong>fspring body weight during treatment, no changes observed<br />

after 0.1% exposure; no altered <strong>of</strong>fspring sexual maturation, higher Pb improved sexual<br />

behavior, while 0.1% reduced it; 0.1% Pb caused decrease in testis weight, an increase<br />

in seminal vesicle weight, and no changes in plasma testosterone levels, hypothalamic<br />

VMA levels were increased compared to control group; reduced birth weight and<br />

growth rates.<br />

Significantly reduced litter size, reduced fetal weight, and a reduced crown-to-rump<br />

length, increased resorption and a higher blood-Pb uptake in those groups receiving<br />

1000 and 2000 ppm Pb; these also had a higher placental uptake; however the level was<br />

the same in both groups; fetal Pb uptake remained the same whether or not 2000 ppm<br />

Pb was given to an iron-deficient or normal iron groups <strong>of</strong> mothers.<br />

Reduced body weight (p = 0.04); parotid function was decreased by nearly 30%<br />

(p = 0.30); higher mean caries scores than the control pups (p = 0.005); pre- and<br />

perinatal Pb exposure had significantly increased susceptibility to dental caries<br />

(p = 0.015).<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

Dams: 0, 48, 88, or 181 µg/dL<br />

Pups PND 1: 120 µg/dL<br />

Pups PND 21: 50, >160, or<br />

~237 µg/dL<br />

Pups PND 35: 70, or<br />

>278 µg/dL<br />

Pups PND 55: 68, >137, or<br />

~380 µg/dL<br />

Pups PND 85: 43, >122, or<br />

>214 µg/dL<br />

PbB at 825 ppm was 67–<br />

192 µg/dL<br />

PbB at 2475 ppm was 120–<br />

388 µg/dL<br />

PbB 36.12 — 9.49 µg/dL or<br />

13.08 ± 9.42 µg/dL<br />

PbB not reported<br />

PbB 48 ± 13 µg/dL


AX5-44<br />

Citation<br />

Wiebe et al.<br />

(1998)<br />

Table AX5-4.1 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Offspring<br />

Species/<br />

Strain/Age<br />

Rats/Sprague-<br />

Dawley, adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

20 or 200 ppm Pb chloride in<br />

drinking water; prior to<br />

pregnancy, during pregnancy,<br />

lactation<br />

*Not including effects on the nervous or immune systems.<br />

† Candidate key study.<br />

Exposure to Pb did not affect tissue weights but did cause a significant decrease in<br />

gonadotropin-receptor binding in the prepubertal, pubertal, and adult females;<br />

conversion <strong>of</strong> progesterone to androstenedione and dihydrotestosterone was<br />

significantly decreased in 21-day old rats, in 150-day old females, the exposure to Pb<br />

resulted in significantly increased conversion to the 5-alpha-reduced steroids, normally<br />

high during puberty.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB 4.0 ± 1.4 to 6.6 ± 2.3 µg/dL<br />

cGMP, cyclic guanosine—3',5'-monophosphate; DO, distraction osteogenesis; DOPAc, 3,4-dihydroxyphenylacetic acid; E2, estradiol; ERG, electroretinographic; FSH, follicle stimulating hormone;<br />

GD, gestational day; IGF1, insulin-like growth factor 1; i.v., intravenous; kDA, kilodalton; LH, luteinizing hormone; NOS, not otherwise specified; PbB, blood Pb concentration; PDE,<br />

phosphodiesterase; PND, post-natal day; p.o., per os (oral administration); s.c., subcutaneous; SEM, standard error mean; UDP, uridine diphosphate; VMA, vanilmandelic acid


AX5-45<br />

Citation<br />

Acharya et al.<br />

(2003)<br />

Adhikari et al.<br />

(2000)<br />

Adhikari et al.<br />

(2001)<br />

Alexaki et al.<br />

(1990)<br />

Al-Hakkak<br />

et al. (1988)<br />

Barratt et al.<br />

(1989)<br />

Bataineh et al.<br />

(1998)<br />

Batra et al.<br />

(2001)<br />

Batra et al.<br />

(2004)<br />

Bizarro et al.<br />

(2003)<br />

Boscolo et al.<br />

(1988)<br />

Table AX5-4.2. Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Mouse/Swiss,<br />

6–8 wks old<br />

Rat/Druckrey,<br />

28 days old<br />

Rat/Druckrey,<br />

28 days old<br />

Bulls/Holstein,<br />

3–5 yrs old<br />

Mouse/<br />

BALB/c,<br />

weaning<br />

Rat/Wistar,<br />

70 days old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Portan,<br />

8 wks old<br />

Rat/Portan,<br />

8 wks old<br />

Mouse/CD-1,<br />

adult<br />

Rat/Sprague-<br />

Dawley,<br />

weanling<br />

200 mg/kg Pb acetate through<br />

i.p. injection <strong>of</strong> Pb; one time<br />

injection<br />

0.0, 0.4, 4.0, 40.0 µM Pb<br />

acetate in vitro <strong>for</strong> 24 and<br />

48 hr<br />

5, 10, and 20 mg/kg Pb in<br />

distilled water by gavage <strong>for</strong><br />

2 wks<br />

In vitro fertilization 2.5 or<br />

0.25 µg/mL<br />

0, 25, 50 mg Pb monoxide<br />

alloy/kg in chow <strong>for</strong> 35–<br />

70 days<br />

0, 0.3, 33, 330 mg Pb<br />

acetate/kg-d in drinking<br />

water, by gavage <strong>for</strong> 63 days<br />

1000 ppm Pb acetate in<br />

drinking water <strong>for</strong> 12 wks<br />

10, 50, 200 mg/kg Pb acetate<br />

orally <strong>for</strong> 3 mo<br />

10, 50, 200 mg/kg Pb acetate<br />

orally <strong>for</strong> 3 mo<br />

0.01 M Pb acetate twice a<br />

week <strong>for</strong> 4 wks<br />

60 mg Pb acetate/mL in<br />

drinking water <strong>for</strong> 18 mo<br />

Testicular weight loss with constant increase in the incidence <strong>of</strong> abnormal sperm<br />

population; decrease in sperm count; testicular ascorbic acid also declined significantly;<br />

significant rise in LPP <strong>of</strong> tissue; LPP is indicative <strong>of</strong> oxidative stress in treated mice<br />

testes.<br />

Germ cells progressively detached from Sertoli cell monolayer into medium in a<br />

concentration and duration dependent manner Viability <strong>of</strong> the detached cells showed a<br />

decrease with increase in time and concentration <strong>of</strong> Pb; leakage <strong>of</strong> LDH recorded at<br />

higher dose <strong>of</strong> 4.0 and 40.0 µM.<br />

Induced significant numbers <strong>of</strong> germ cells to undergo apoptosis in the semiferous<br />

tubules <strong>of</strong> rats treated with highest dose; DNA fragmentation was not detected at any <strong>of</strong><br />

the doses; level <strong>of</strong> Pb accumulation in testes increased in a dose-dependent manner.<br />

Sperm motility reduced significantly at 2.5 µg/mL; lower concentration had no effect<br />

on sperm motility.<br />

Reduced number <strong>of</strong> spermatogenia and spermatocytes in the 50 mg group after 70 days;<br />

reduced number <strong>of</strong> implantations after mating (after 35 days exposure).<br />

Increased number <strong>of</strong> abnormal post-testicular sperm in the highest exposure group;<br />

reduced number <strong>of</strong> spermatozoa at PbB >4.5 µg/dL.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

Not reported<br />

PbB not applicable–in vitro study<br />

PbB not reported<br />

PbB not applicable–in vitro study<br />

PbB not reported<br />

PbB 2, 4.5, 7, 80 µg/dL<br />

PbBs >40 µg/dL<br />

Fertility was reduced in males. PbB not reported<br />

Pb in testis and epididymis increased with dose; administration <strong>of</strong> zinc reduced Pb PbB not reported<br />

levels; dose related changes in activities <strong>of</strong> enzyme alkaline phosphatase and Na+-K+-<br />

ATPase, which decreased with increased dose <strong>of</strong> Pb; improvement in activities <strong>of</strong><br />

enzymes was seen in groups given Pb and zinc; disorganization and disruption <strong>of</strong><br />

spermatogenesis with accumulation <strong>of</strong> immature cells in lumen <strong>of</strong> tubule; highest dose<br />

<strong>of</strong> Pb resulted in arrest <strong>of</strong> spermatogenesis, and decrease in germ cell layer population;<br />

highest dose levels, damage <strong>of</strong> basement membrane, disorganization <strong>of</strong> epithelium and<br />

vacuolization cells; tubules were found almost empty, indicating arrest <strong>of</strong><br />

spermatogenesis.<br />

LH and FSH concentrations were decreased at 200 mg/kg; decrease in fertility status at PbB not reported<br />

200 mg/kg; decline in various cell populations at 200 mg/kg; 50 mg/kg group hormone<br />

levels, cell numbers, and fertility status were found close to normal.<br />

Dose-time relationship was found; ROS role. PbB not reported<br />

Increased vacuolization in Sertoli cells; no other ultrastructural modifications; no<br />

impairment <strong>of</strong> spermatogenesis.<br />

PbB 4–17 µg/dL


AX5-46<br />

Citation<br />

Chowdhuri<br />

et al. (2001)<br />

Chowdhury<br />

et al. (1984)<br />

Chowdhury<br />

et al. (1986)<br />

Chowdhury<br />

et al. (1987)<br />

C<strong>of</strong>figny et al.<br />

(1994) †<br />

Corpas et al.<br />

(1995)<br />

Corpas et al.<br />

(2002a)<br />

Corpas et al.<br />

(2002b)<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Mouse/<br />

BALB/c,<br />

3 mo old<br />

Rat/Albino,<br />

(NOS), adult<br />

0.0, 0.2, 0.5, 1.0, 2.0 µg/mL<br />

Pb acetate in culture medium<br />

<strong>for</strong> 2 hr (superovulated ova<br />

and sperm)<br />

Dietary concentrations <strong>of</strong><br />

0.25, 0.50, or 1.0 g/L Pb<br />

acetate <strong>for</strong> 60 days<br />

Rat/NOS, adult 0, 1, 2, 4, 6 mg Pb<br />

acetate/kg-d i.p.<br />

<strong>for</strong> 30 days<br />

Rat/Charles<br />

Foster,<br />

150 ± 5 g<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Wistar,<br />

adult<br />

Rat/Wistar,<br />

adult<br />

Rat/Wistar,<br />

adult<br />

0, 1, 2, 4, 6 mg Pb<br />

acetate/kg-d/i.p.<br />

<strong>for</strong> 30 days<br />

Inhalation exposure to<br />

5 mg/m 3 Pb oxide daily <strong>for</strong><br />

13 days during gestation<br />

(GD 2, 3, 6–10, 13–17, 20)<br />

300 mg/L Pb acetate via<br />

drinking water beginning GD<br />

1 through 5 days postnatal or<br />

throughout gestation and<br />

early lactation<br />

300 mg/L acetate Pb in<br />

drinking water beginning at<br />

mating until PND 12 and 21<br />

300 mg/L acetate Pb in<br />

drinking water beginning at<br />

mating until PND 12 and 21<br />

Significant dose dependent decrease in the number <strong>of</strong> sperm attaching to the ova in both<br />

exposed groups; decrease in the incorporation <strong>of</strong> radio-labeled thymdine, uridine, and<br />

methionine.<br />

Testicular atrophy along with cellular degeneration was conspicuous at 1 g/L; high<br />

cholesterol concentration and significantly low ascorbic acid concentration were found<br />

in the testes at 1 g/L; lowest dose (0.25 g/L) had no significant morphological and<br />

biochemical alterations, whereas as 0.5 g/L resulted in partial inhibition <strong>of</strong><br />

spermatogenesis.<br />

Dose-related decrease <strong>of</strong> testis weight; at 187 µg/dL: degenerative changes in testicular<br />

tissues; at 325 µg/dL: degenerative changes and inquiry <strong>of</strong> spermatogenetic cells;<br />

edematous dissociation in interstitial tissue.<br />

Dose related decrease <strong>of</strong> testis weight at 56 µg <strong>of</strong> spermatoids; at 91 µg/dL: inhibition<br />

<strong>of</strong> post-meiotic spermatogenic cell; at 196 µg/dL: decreased spermatogenic cell count<br />

(6), detachment <strong>of</strong> germinal call layers; at 332 µg/dL: Decreased spermatogenic cell<br />

count, degenerative changes, Interstitial edema, and atrophy <strong>of</strong> Leydig cells.<br />

Adult male <strong>of</strong>fspring exhibit no change in sperm parameters or sex hormones T, FSH,<br />

and LH (because <strong>of</strong> duration or timing).<br />

Testicular weight and gross testicular structure were not altered; seminiferous tubule<br />

diameter and the number <strong>of</strong> prospermatogonia were reduced; total DNA, RNA, and<br />

protein content <strong>of</strong> the testes in treated rats was significantly reduced, DNA:RNA ratio<br />

remained unaltered.<br />

Neither abnormalities in the liver structure nor depositions <strong>of</strong> Pb, toxicant produced<br />

biochemical alterations; pups exhibited decrease in hemoglobin, iron and alkaline, and<br />

acid phosphatase levels and an increase in Pb content; protein, DNA, and lipid total<br />

amounts were reduced, and hepatic glycogen content was diminished at 12 and 21 PN,<br />

with a higher dose <strong>of</strong> glucose in blood; decrease in alkaline phosphatase in liver <strong>of</strong> pups<br />

at day 21 PN, but acid phosphatase was unaltered.<br />

Neither abnormalities in the liver structure nor depositions <strong>of</strong> Pb, toxicant produced<br />

biochemical alterations; pups exhibited decrease in hemoglobin, iron and alkaline, and<br />

acid phosphatase levels and an increase in Pb content; protein, DNA, and lipid total<br />

amounts were reduced, and hepatic glycogen content was diminished at 12 and 21 PN,<br />

with a higher dose <strong>of</strong> glucose in blood; decrease in alkaline phosphatase in liver <strong>of</strong> pups<br />

at day 21 PN, but acid phosphatase was unaltered.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not applicable–in vitro study<br />

PbB 54–143 µg/dL<br />

PbB 20, 62, 87, 187, or<br />

325 µg/dL<br />

PbB 56–3332 µg/dL<br />

PbB 71.1 µg/dL (dam)<br />

PbB 83.2 µg/dL (fetal)<br />

PbB 14 µg/dL<br />

PbB 22 µg/dL<br />

PbB 22 µg/dL


AX5-47<br />

Citation<br />

Cory-Slechta<br />

et al. (2004) †<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Rat/Long-Evans,<br />

adult<br />

Foote (1999) Rabbit/Dutchbelted,<br />

adult<br />

Foster et al.<br />

(1993)<br />

Foster et al.<br />

(1996a)<br />

Foster et al.<br />

(1998)<br />

Gandley et al.<br />

(1999)<br />

Gorbel et al.<br />

(2002)<br />

Monkey/<br />

Cynomolgus,<br />

adult<br />

Monkey/<br />

Cynomolgus,<br />

adult<br />

Monkey/<br />

Cynomolgus,<br />

adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/(NOS),<br />

90 days old<br />

Pb acetate in drinking water<br />

beginning 2 mo be<strong>for</strong>e<br />

breeding until the end <strong>of</strong><br />

lactation<br />

0, 0.005, 0.01, and 0.025 mM<br />

PbCl2 in vitro; one time dose<br />

0–1500 µg Pb acetate/kg-d in<br />

gelatin capsules p.o. <strong>for</strong><br />

various durations: 9 control<br />

monkeys, 4 monkeys in<br />

lifetime group (birth to 9 yrs),<br />

4 in infancy group (first<br />

400 days <strong>of</strong> life), 4 in postinfancy<br />

exposure (from<br />

300 days to 9 yrs)<br />

0–1500 µg Pb acetate/kg-d in<br />

gelatin capsules p.o. from<br />

birth until 9 yrs <strong>of</strong> age:<br />

8 control monkeys, 4<br />

monkeys in low group<br />

(6-20 µg/dL), 7 monkeys in<br />

high group (22–148 µg/dL)<br />

0–1500 µg Pb acetate/kg-d in<br />

gelatin capsules p.o. <strong>for</strong><br />

various durations: birth to<br />

10 yrs (lifetime); PND 300 to<br />

10 yrs (post-infancy); birth to<br />

300 days (infancy); 3 control<br />

monkeys, 4 lifetime,<br />

4 infancy, 5 post-infancy<br />

Male rats received Pb acetate<br />

25 or 250 ppm in drinking<br />

water <strong>for</strong> 35 days prior to<br />

mating<br />

3 mg (P1) or 6 mg (P2) Pb<br />

acetate in drinking water <strong>for</strong><br />

15, 30, 45, 60, or 90 days<br />

Observed potential effects <strong>of</strong> Pb and stress in female; Pb alone (in male) and Pb plus<br />

stress (in females) permanently elevated corticosterene levels in <strong>of</strong>fspring.<br />

Six out <strong>of</strong> 22 males tested showed appreciable spontaneous hyperactivation, Pb did not<br />

affect hyperactivation, or associated capacitation.<br />

Suppressed LH response to GnRH stimulation in the lifetime group (p = 0.0370);<br />

Sertoli cell function (reduction in the inhibin to FSH ratio) (p = 0.0286) in lifetime and<br />

post-infancy groups.<br />

Mean PbB <strong>of</strong> 56 µg/dL showed no significant alterations in parameters <strong>of</strong> semen<br />

quality (count, viability, motility, or morphology).<br />

Circulating concentrations <strong>of</strong> FSH, LH, and testosterone were not altered by treatment;<br />

semen characteristics (count, motility, morphology) were not affected by treatment<br />

possibly because not all Sertoli cells were injured; degeneration <strong>of</strong> seminiferous<br />

epithelium in infancy and lifetime groups (no difference in severity between these<br />

groups); ultrastructural alterations in seminal vesicles, most prominent in infancy and<br />

post-infancy groups.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB 30–40 µg/dL<br />

PbB not applicable–in vitro study<br />

Lifetime group 3–26 µg/dL at<br />

4–5 yrs; infancy group<br />

5–36 µg/dL at 100–300 days,<br />

3–3 µg/dL at 4–5 yrs; postinfancy<br />

group 20–35 µg/dL<br />

PbB 10 ± 3 or 56 ± 49 µg/dL<br />

PbB ~35 µg/dL<br />

High dose reduced fertility; low dose altered genomic expression in <strong>of</strong>fspring. PbB 15–23 µg/dL or<br />

27–60 µg/dL<br />

Male rats, absolute and relative weights <strong>of</strong> testis, epididymis, prostate and seminal<br />

vesicles were found to significantly decrease at day 15 in P2 group and at day 45 in P1<br />

group, at day 60 these absolute values and relative weights returned to control values; at<br />

day 15 arrest <strong>of</strong> cell germ maturation, changes in the Sertoli cells, and presence <strong>of</strong><br />

apoptotic cells were observed; serum testosterone level was found to be lowered at day<br />

15 in both P1 and P2, and peaked at day 60, then returned to normal values.<br />

PbB not reported


AX5-48<br />

Citation<br />

Graca et al.<br />

(2004)<br />

Hsu et al.<br />

(1997)<br />

Hsu et al.<br />

(1998a)<br />

Hsu et al.<br />

(1998b)<br />

Huang et al.<br />

(2002)<br />

Johansson<br />

(1989)<br />

Johansson and<br />

Pellicciari<br />

(1988)<br />

Johansson and<br />

Wide (1986)<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Mouse/CD-1,<br />

2 mo old<br />

Rat/Sprague-<br />

Dawley, 7 wks<br />

old<br />

Rat/Sprague-<br />

Dawley,<br />

100–120 g<br />

Rat/Sprague-<br />

Dawley, 7 wks<br />

old<br />

Mouse MA-10<br />

cells<br />

Mouse, 9 wks<br />

old<br />

Mouse/NMRI,<br />

9 wks old<br />

Mouse/NMRI,<br />

9 wks old<br />

Subcutaneous injection <strong>of</strong><br />

74 mg/kg-d <strong>of</strong> Pb chloride <strong>for</strong><br />

1 to 3 days<br />

10 mg/kg Pb acetate through<br />

i.p. injection to males <strong>for</strong> 6 or<br />

9 wks<br />

20 or 50 mg Pb acetate via<br />

i.p. route weekly to males <strong>for</strong><br />

6 wks<br />

10 mg/kg Pb acetate weekly<br />

via i.p. injection to males <strong>for</strong><br />

6 wks<br />

10 −8 to 10 −5 M Pb incubated<br />

<strong>for</strong> 3 hr<br />

0–1 g Pb chloride/L in<br />

drinking water <strong>for</strong> 112 days<br />

1 g/L Pb chloride in drinking<br />

water <strong>for</strong> 16 wks<br />

0–1 g/L Pb chloride in<br />

drinking water <strong>for</strong> 84 days<br />

Reversible changes in sperm (count) and ultrastructural changes in testes (reduced<br />

diameter <strong>of</strong> seminiferous tubules).<br />

Six-week group had unchanged epididymal sperm counts, percent <strong>of</strong> motile sperms, and<br />

motile epididymal sperm counts compared with control group; 9-wk group showed<br />

statistically lower epididymal sperm counts, and lower motile epididymal sperm counts;<br />

good correlation between blood Pb and sperm Pb; significantly higher counts <strong>of</strong><br />

chemiluminescence, they were positively associated with sperm Pb level; epididymal<br />

sperm counts, motility, and motile epididymal sperm counts were negatively associated<br />

with sperm chemiluminescence; SOPR were positively associated with epididymal<br />

sperm counts, motility and motile epididymal sperm counts, sperm chemiluminescence<br />

was negatively associated with SOPR.<br />

Serum testosterone levels were reduced; percentage <strong>of</strong> capacitation and the<br />

chemiluminescence were significantly increased in fresh cauda epididymal<br />

spermatozoa; serum testosterone levels were negatively associated with the percentage<br />

<strong>of</strong> acrosome-reacted spermatozoa; sperm chemiluminescence was positively correlated<br />

with the percentage <strong>of</strong> both capacitated and acrosome-reacted spermatozoa; SOPR was<br />

negatively associated with the percentage <strong>of</strong> both capacitated and acrosome-reacted<br />

spermatozoa.<br />

Intake <strong>of</strong> VE and/or VC in Pb exposed rats prevented the Pb associated sperm ROS<br />

generation, increased the epididymal sperm motility, enhanced the capacity <strong>of</strong> sperm to<br />

penetrate eggs harvested from unexposed female rats in vitro; protective effect <strong>of</strong> VE<br />

and VC not associated with reduced blood or sperm Pb levels.<br />

Higher decreases in human chorionic gonadotropin (hCG)-stimulated progesterone<br />

production, expressions <strong>of</strong> StAR protein, and the activity <strong>of</strong> 3ß-HSD compared to 2 hr;<br />

no affect on P450scc enzyme activity.<br />

No effects on frequency <strong>of</strong> motile spermatozoa, nor on swimming speed; decreased<br />

fertilizing capacity <strong>of</strong> the spermatozoa by in vitro fertilization; premature acrosome<br />

reaction .<br />

Decreased uptake <strong>of</strong> PI was found in spermatozoa from the vas deferens <strong>of</strong> the Pbexposed<br />

mice; after thermal denaturation <strong>of</strong> the DNA, the spermatozoa showed a higher<br />

uptake <strong>of</strong> PI in comparison to those <strong>of</strong> the controls; after reductive cleavage <strong>of</strong> S-S<br />

bonds with DTT and staining with a thiol-specific reagent significantly fewer reactive<br />

disulfide bonds were also observed in the spermatozoa; significant delay in the capacity<br />

<strong>for</strong> NCD was noted.<br />

No effects on sperm count; no effects on serum testosterone; reduced number <strong>of</strong><br />

implantations after mating.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not reported<br />

PbB after 6 wks 32 µg/dL, after<br />

9 wks 48 ± 4.3 µg/dL<br />

PbBs >40 µg/dL<br />

PbB 30.1 ± 3.4 to 36.1 ± 4.6<br />

PbBs >40 µg/dL<br />

PbB not applicable–in vitro study<br />

PbB 0.5–40 µg/dL<br />

PbB 42 ± 1.6 µg/dL<br />

PbB


AX5-49<br />

Citation<br />

Johansson<br />

et al. (1987)<br />

Kempinas<br />

et al. (1988)<br />

Kempinas<br />

et al. (1990)<br />

Kempinas<br />

et al. (1994)<br />

Klein et al.<br />

(1994)<br />

Liu et al.<br />

(2001)<br />

Liu et al.<br />

(2003)<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Mouse/NMRI,<br />

9–10 wks old<br />

Rat/Wistar,<br />

adult<br />

Rat/NOS,<br />

pubertal<br />

Rat/Wistar,<br />

50 days old<br />

Rat/Sprague-<br />

Dawley,<br />

100 days old<br />

Mouse,<br />

MA-10 cells<br />

Mouse,<br />

MA-10 cells<br />

1 g/L Pb chloride in drinking<br />

water <strong>for</strong> 16 wks<br />

0.5 g/L and 1.0 g/L Pb acetate<br />

in drinking water <strong>for</strong> 90 days<br />

(1.0 g/L) Pb acetate in<br />

drinking water in addition to<br />

i.v. injections <strong>of</strong> Pb acetate<br />

(0.1 mg/100 g bw) every<br />

10 days, 20 days<br />

(1.0 g/L) Pb acetate in<br />

drinking water in addition to<br />

i.v. injections <strong>of</strong> Pb acetate<br />

(0.1 mg/100 g bw) every<br />

15 days, 9 mo<br />

0–1 g Pb acetate/L in<br />

drinking water + 0.1 mg/kg<br />

i.v. every 10 days <strong>for</strong> 20 days<br />

0–1 g Pb acetate/L in<br />

drinking water + 0.1 µg/kg<br />

i.v. every 15 days <strong>for</strong><br />

270 days<br />

0.1, 0.3, or 0.6% Pb acetate in<br />

distilled water <strong>for</strong> 21 days<br />

10 −8 to 10 −5 Pb acetate in<br />

vitro <strong>for</strong> 2 hr<br />

10 −8 to 10 −5 Pb acetate in<br />

vitro <strong>for</strong> 6 hr incubated<br />

Spermatozoa had significantly lower ability to fertilize mouse eggs; morphologically<br />

abnormal embryos were found.<br />

PbB exhibited a significant increase in both groups; decrease in hematocrit and<br />

hemoglobin, together with a rise in glucose levels; no signs <strong>of</strong> lesion were detected<br />

upon histological examination <strong>of</strong> testes, caput, and cauda epididymidis; an increase in<br />

ductal diameter, and a decrease in epithelial height were observed in the cauda<br />

epididymidis; concentration <strong>of</strong> spermatozoa stored in the caudal region <strong>of</strong> the<br />

epididymis exhibited a significant increase in Pb-treated animals.<br />

Basal levels <strong>of</strong> testosterone were higher both in the plasma and in the testes <strong>of</strong> acutely<br />

intoxicated animals; levels <strong>of</strong> LH were not affected in either group, nor was the LHRH<br />

content <strong>of</strong> the median eminence; density <strong>of</strong> LH/hCG binding sites in testicular<br />

homogenates was reduced by saturnism in both groups, apparent affinity constant <strong>of</strong> the<br />

hormone-receptor, complex significantly increased.<br />

Increased plasma and testicular testosterone concentrations; no effects on testicular<br />

weight; reduced weight <strong>of</strong> prostate; increased weight <strong>of</strong> seminal vesicle and seminal<br />

secretions.<br />

2–3-fold enhancement <strong>of</strong> mRNA levels <strong>of</strong> GnRH and the tropic hormone LH; 3-fold<br />

enhancement <strong>of</strong> intracellular stores <strong>of</strong> LH; mRNA levels <strong>of</strong> LH and GnRH and pituitary<br />

levels <strong>of</strong> stored LH are proportional to blood levels <strong>of</strong> Pb.<br />

Significantly inhibited hCG- and dbcAMP-stimulated progesterone production in<br />

MA-10 cells; steroid production stimulated by hCG or dbcAMP were reduced by Pb;<br />

expression <strong>of</strong> StAR protein and the activities <strong>of</strong> P450 side-chain cleavage (P450) and<br />

3ß-HSD enzymes detected; expression <strong>of</strong> StAR protein stimulated by bdcAMP was<br />

suppressed by Pb at about 50%; progesterone productions treated with 22Rhydroxycholesterol<br />

or pregnenolone were reduced 30–40% in Pb treated MA-10 cells.<br />

Pb significantly inhibited hCG- and dbcAMP-stimulated progesterone production from<br />

20 to 35% in MA-10 cells at 6 hr; Pb suppressed the expression <strong>of</strong> steriodogenesis acute<br />

regulatory (StAR) protein from 30 to 55%; activities P450 side-chain cleavage<br />

(P450scc) enzyme and 3ß-HSD were reduced by Pb from 15 to 25%.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not reported<br />

PbB 65–103 µg/dL<br />

PbB ~40 µg/dL<br />

PbB 10–41 µg/dL<br />

PbB 8.5–40 µg/dL<br />

PbB 42–102 µg/dL<br />

PbB not applicable–in vitro study<br />

PbB not applicable–in vitro study


AX5-50<br />

Citation<br />

Marchlewicz<br />

et al. (1993)<br />

McGivern<br />

et al. (1991) †<br />

McMurry<br />

et al. (1995)<br />

Mishra and<br />

Acharya<br />

(2004)<br />

Moorman<br />

et al. (1998)<br />

Murthy et al.<br />

(1991)<br />

Murthy et al.<br />

(1995)<br />

Nathan et al.<br />

(1992)<br />

Pace et al.<br />

(2005)<br />

Piasecka et al.<br />

(1995)<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Rat/Wistar,<br />

90 days old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Cotton,<br />

adult<br />

Mouse/Swiss,<br />

9–10 wks old<br />

Rabbit/NOS,<br />

adult<br />

Rat/ITRC,<br />

(NOS),<br />

weanling<br />

Rat/Druckrey,<br />

adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Mouse/BALB/c,<br />

adult<br />

Rat/Wistar,<br />

adult<br />

0–1% Pb acetate in drinking<br />

water <strong>for</strong> 270 days<br />

0.1% Pb acetate in drinking<br />

water from GD 14 to<br />

parturition: 8 control litters;<br />

6 Pb acetate litters (5 males<br />

per litter)<br />

0, 100, or 1000 ppm Pb in<br />

drinking water <strong>for</strong> 7 or<br />

13 wks<br />

10 mg/kg Pb acetate in<br />

drinking water <strong>for</strong> 5 to 8 wks<br />

3.85 mg/kg Pb acetate<br />

subcutaneous injection <strong>for</strong><br />

15 wks<br />

0–250 ppm Pb acetate in<br />

drinking water <strong>for</strong> 70 days<br />

Pb 5 mg/kg i.p. Pb acetate in<br />

drinking water <strong>for</strong> 16 days<br />

0, 0.05, 0.1, 0.5, or 1% Pb<br />

acetate in drinking water <strong>for</strong><br />

70 days<br />

0.1 ppm Pb acetate in<br />

drinking water (lactational<br />

exposure as neonates and<br />

drinking water from PND 21<br />

to PND 42)<br />

1% aqueous solution <strong>of</strong> Pb<br />

acetate <strong>for</strong> 9 mo<br />

No histological or weight changes in testicle or epididymis; fever spermatozoa in all<br />

zones <strong>of</strong> the epididymis.<br />

Decreased sperm count (21% at 70 days and 24% at 165 days; p < 0.05); reduced male<br />

behavior (p < 0.05); enlarged prostate (25% increase in weight; p < 0.07); irregular<br />

release patterns <strong>of</strong> both FSH and LH (p < 0.05).<br />

Immune function was sensitive to Pb exposure; spleen mass was reduced in cotton rats<br />

receiving 100 ppm Pb; total leukocytes, lymphocytes, neutrophils, eosinophils, total<br />

splenocyte yield, packed cell volume, hemoglobin, and mean corpuscular hemoglobin<br />

were sensitive to Pb exposure; reduced mass <strong>of</strong> liver, seminal vesicles, and epididymis<br />

in males after 7 wk exposure.<br />

Stimulates lipid peroxidation in the testicular tissue, associated with increased<br />

generation <strong>of</strong> noxious ROS; reduced sperm count, increased sperm abnormality<br />

Increased blood levels associated with adverse changes in the sperm count, ejaculate<br />

volume, percent motile sperm, swimming velocities, and morphology; hormonal<br />

responses were minimal; dose-dependent inhibition <strong>of</strong> sperm <strong>for</strong>mation; semen quality,<br />

threshold estimates ranged from 16 to 24 µg/dL.<br />

At 20 µg/dL no impairment <strong>of</strong> spermatogenesis; vacuolization <strong>of</strong> Sertoli cell cytoplasm<br />

and increase in number and size <strong>of</strong> lysosomes.<br />

Swelling <strong>of</strong> nuclei and acrosomes round spermatids; in Sertoli cells, nuclei appeared<br />

fragmented, whereas the cytoplasm exhibited a vacuolated appearance and a few<br />

structures delimitated by a double membrane that contains microtubules arranged in<br />

parallel and cross-striated fin fibrils, cell tight junction remain intact; no significant<br />

change in epididymal sperm motility and counts, testicular blood levels were found to<br />

be elevated after Pb exposure.<br />

No effects on spermatogenesis in all groups; at 124 µg/dL: decreased seminal vesicle<br />

weight; decreased serum testosterone in the 0.5% group at 10 wks; no effects in the<br />

other exposure categories; no effects on serum FSH, LH, nor pituitary LH content.<br />

Reduction in fertility when mated with unexposed females; no change in sperm count;<br />

increase in number <strong>of</strong> apoptotic cells in testes.<br />

Pb-loaded (electron dense) inclusions were found in the cytoplasm <strong>of</strong> the epididymal<br />

principal cells, especially in the caput <strong>of</strong> epididymis, also present, but smaller, in<br />

smooth muscle cells; inclusions were located in the vacuoles, rarely without any<br />

surrounding membrane; similar Pb-containing structures were found in the epididymal<br />

lumen.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not reported<br />

Control PbB


AX5-51<br />

Citation<br />

Piasek and<br />

Kostial (1987)<br />

Pinon-<br />

Lataillade<br />

et al. (1993)<br />

Pinon-<br />

Lataillade<br />

et al. (1995)<br />

Rodamilans<br />

et al. (1988)<br />

Ronis et al.<br />

(1996) †<br />

Ronis et al.<br />

(1998a)<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Rat/Albino,<br />

(NOS), adult<br />

Rat/Sprague-<br />

Dawley,<br />

90 days old<br />

Mouse/NMRI,<br />

adult<br />

Mouse/BALB/c,<br />

63 days old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

1500, 3500, and 5500 ppm <strong>of</strong><br />

Pb acetate in drinking water<br />

<strong>for</strong> 18 wks<br />

0–0.3% Pb acetate in<br />

drinking water <strong>for</strong> 70 days<br />

5 mg/m 2 Pb oxide in aerosol<br />

<strong>for</strong> 6 hr/day, 5 days/wk,<br />

90 days<br />

0–0.5% Pb acetate in<br />

drinking water, day 1 <strong>of</strong><br />

gestation until 60 days <strong>of</strong> age<br />

0–366 mg Pb acetate/L in<br />

drinking water <strong>for</strong> 30, 60, 90,<br />

120, 150, 180 days<br />

0.6% Pb acetate in drinking<br />

water <strong>for</strong> various durations:<br />

PND 24–74 (pubertal<br />

exposure); PND 60–74 (post<br />

pubertal exposure); 11 males<br />

and females in pubertal<br />

exposure group (10 each in<br />

control pubertal group);<br />

6 males and females postpubertal<br />

exposure and control<br />

groups<br />

0.6% Pb acetate in drinking<br />

water ad libitum <strong>for</strong> various<br />

durations as follows: GD 5 to<br />

PND 1; GD 5 to weaning;<br />

PND 1 to weaning; 3 control<br />

litters, 2 gestation exposure<br />

litters, 2 lactation exposure<br />

litters, 2 gestation and<br />

lactation exposure litters,<br />

2 postnatal exposure litters,<br />

2 chronic exposure litters;<br />

4 male and 4 female pups<br />

per litter.<br />

No overt signs <strong>of</strong> general toxicity in adult female rats, only at the end <strong>of</strong> the exposure<br />

period the mean body weight <strong>of</strong> males exposed to two higher levels was slightly lower;<br />

no effect <strong>of</strong> Pb exposure on male fertility either after first or after second mating; values<br />

in the pups did not differ from control group.<br />

Decreased weight <strong>of</strong> seminal vesicles in inhalation study; no effects on spermatogenesis<br />

(epididymal sperm count, spermatozoal motility or morphology) or plasma testosterone,<br />

LH, and FSH; no effects on fertility; decrease in epididymal sperm count <strong>of</strong> progeny <strong>of</strong><br />

sires <strong>of</strong> the inhalation group, however without effect on their fertility.<br />

No effects on testicular histology, nor on number and morphology <strong>of</strong> epididymal<br />

spermatozoa; no effects on plasma FSH, LH, and testosterone, nor on testicular<br />

testosterone; decreased weight <strong>of</strong> testes, epididymis, seminal vesicles, and ventral<br />

prostate; no effects on fertility.<br />

Reduction <strong>of</strong> intratesticular testosterone concentrations after 30 days; reduction <strong>of</strong> and<br />

renostenedione concentrations after 150 days; no changes in intratesticular progesterone<br />

and hydroxy-progesterone.<br />

PbB > 250 µg/dL reduced circulating testosterone levels in male rats 40–50%<br />

(p < 0.05); reduction in male secondary sex organ weight (p < 0.005); delayed vaginal<br />

opening (p < 0.0001); disrupted estrous cycle in females (50% <strong>of</strong> rats); increased<br />

incidence <strong>of</strong> stillbirth (2% control vs. 19% Pb) (p < 0.005).<br />

Suppression <strong>of</strong> adult mean serum testosterone levels was only observed in male pups<br />

exposed to Pb continuously from GD 5 throughout life (p < 0.05).<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not reported<br />

PbB 58 ± 1.7 µg/dL (oral)<br />

PbB 51.1 ± 1.8 µg/dL<br />

(inhalation)<br />

PbB


AX5-52<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Citation Species/ Strain/Age Dose/Route/Form/Duration Endpoint<br />

Ronis et al.<br />

(1998b)<br />

Ronis et al.<br />

(1998c) †<br />

Sant'Ana<br />

et al. (2001)<br />

Saxena et al.<br />

(1984)<br />

Saxena et al.<br />

(1986)<br />

Saxena et al.<br />

(1987)<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Wistar, 90 days<br />

old<br />

Rat/ITRC, albino<br />

(NOS), 12 wks old<br />

Rat/ITRC, albino<br />

(NOS), 40–50 g<br />

Rat/Wistar, 40–50 g<br />

Pb acetate in drinking water<br />

(0.05% to 0.45% w/v); dams<br />

exposed until weaning,<br />

exposure <strong>of</strong> pups which<br />

continued until PND 21, 35,<br />

55, or 85; 5 control litters<br />

(0%), 10 low-dose litters<br />

(0.05%), 8 mid-dose litters<br />

(0.15%), 9 high-dose litters<br />

(0.45%); 4 male and 4 female<br />

pups per litter<br />

Pb acetate 0.05, 0.15, or<br />

0.45% in drinking water<br />

beginning GD 5 continuing<br />

until PND 21, 35, 55, or 85;<br />

5 control litters (0%), 10 lowdose<br />

litters (0.05%), 8 middose<br />

litters (0.15%), 9 highdose<br />

litters (0.45%); 4 male<br />

and 4 female pups per litter<br />

0.1 and 1% Pb acetate in<br />

drinking water <strong>for</strong> 7 days<br />

8 mg/kg Pb acetate i.p. <strong>for</strong><br />

15 days<br />

5, 8, or 12 mg Pb+2/kg Pb<br />

acetate i.p. <strong>for</strong> 15 days<br />

8 mg Pb2/kg-d Pb acetate i.p.<br />

<strong>for</strong> 100 days (from PND 21 to<br />

PND 120)<br />

Dose-response reduction in birth weight (p < 0.05), more pronounced in male pups;<br />

decreased growth rates in both sexes (p < 0.05) were accompanied by a statistically<br />

significant decrease in plasma concentrations <strong>of</strong> IGF1 through puberty PND 35 and<br />

55 (p < 0.05); increase in pituitary growth hormone during puberty (p < 0.05).<br />

Dose-responsive decrease in birth weight (p < 0.05); dose-responsive decrease in<br />

crown-to-rump length (p < 0.05); dose-dependent delay in sexual maturity (p < 0.05);<br />

decrease in prostate weight (p < 0.05); decrease in plasma concentration <strong>of</strong><br />

testosterone during puberty (p < 0.05); decrease in plasma LH (p < 0.05); elevated<br />

pituitary LH content (p < 0.05); decrease in plasma testosterone/LH ratio at high dose<br />

(p < 0.05).<br />

0.1% Pb caused decrease in testis weight, an increase in seminal vesicle weight and<br />

no changes in plasma testosterone levels, hypothalamic VMA levels were increased<br />

compared to control group.<br />

Histoenzymic and histological alterations in the testes; degeneration <strong>of</strong> seminiferous<br />

tubules; patchy areas showing marked loss in the activity <strong>of</strong> succinic dehydrogenase<br />

and adenosine triphosphatase, whereas alkaline phosphatase activity showed only<br />

slight inhibition.<br />

Increasing dose <strong>of</strong> Pb resulted in significant loss <strong>of</strong> body weight, as well as testicular<br />

weight in groups 3 and 4; cholesterol in the testis <strong>of</strong> rats markedly decreased at all<br />

given doses <strong>of</strong> Pb and was statistically significant in groups 3 and 4; in phospholipid<br />

contents, the significant decrease was observed only at two highest doses, while at the<br />

lowest dose the decrease was not significant; activity <strong>of</strong> ATPase remained unaffected<br />

at all three doses <strong>of</strong> Pb; no significant increase in Pb content in the testis was noticed<br />

at lower dose levels as compared to control; however, significant increase was found<br />

in groups 3 and 4 which was dose dependent.<br />

Disturbed spermatogenesis; Leydig cell degeneration; altered enzyme activity<br />

(G6PDH).<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

Mean PbB in <strong>of</strong>fspring at 0.05%<br />

(w/v) 49 ± 6 µg/dL<br />

Mean PbB in <strong>of</strong>fspring at 0.15%<br />

(w/v) 126 ± 16 µg/dL<br />

Mean PbB in <strong>of</strong>fspring at 0.45%<br />

(w/v) 263 ± 28 µg/dL<br />

Dams: 0, 48, 88, or 181 µg/dL<br />

Pups PND 1:


AX5-53<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Citation Species/Strain/Age Dose/Route/ Form/Duration Endpoint<br />

Saxena et al.<br />

(1990)<br />

Singh et al.<br />

(1993a)<br />

ITRC albino,<br />

(NOS), adult<br />

Monkey/<br />

Cynomolgus, birth<br />

Birth:<br />

300 days:<br />

Sokol (1987) Rat/Wistar, 52 days<br />

old<br />

Sokol (1989) Rat/Wistar, 27 days<br />

old<br />

8 mg/kg/d Pb acetate <strong>for</strong><br />

45 days<br />

0–1500 µg Pb acetate/kg-d in<br />

gelatin capsules <strong>for</strong> various<br />

durations: 3 control<br />

monkeys, 4 monkeys in<br />

infancy group (exposure first<br />

400 days), 5 in post-infancy<br />

group (exposure 300 days to<br />

9 yrs <strong>of</strong> age), 4 in lifetime<br />

group (exposure from birth<br />

until 9 yrs)<br />

0–0.3% Pb acetate in<br />

drinking water <strong>for</strong> 30 days<br />

0–0.6% Pb acetate in<br />

drinking water <strong>for</strong> 30 days +<br />

30 days recovery<br />

52 days old 0–0.6% Pb acetate in<br />

drinking water <strong>for</strong> 30 days +<br />

30 days recovery<br />

Sokol (1990) Rat/Wistar, 52 days<br />

old<br />

Sokol and<br />

Berman<br />

(1991)<br />

0–0.6% Pb acetate in<br />

drinking water <strong>for</strong> 7, 14, 30,<br />

60 days<br />

Rat/Wistar, NOS 0, 0.1, or 0.3% Pb acetate in<br />

drinking water <strong>for</strong> 30 days<br />

beginning at 42, 52, or<br />

70 days old; 8–11 control rats<br />

<strong>for</strong> each age, 8–11 rats <strong>for</strong><br />

each age in 0.1% group, 8–<br />

11 rats <strong>for</strong> each age in 0.3%<br />

group<br />

Alterations in SDH, G6PDH activity, cholesterol, and ascorbic acid contents and<br />

reduced sperm counts associated with marked pathological changes in the testis,<br />

after combined treatment with Pb and immobilization stress in comparison to either<br />

alone.<br />

Degeneration <strong>of</strong> seminiferous epithelium in all exposed groups (frequency not<br />

specified); ultrastructural alterations in seminal vesicles, most prominent in infancy<br />

and post-infancy groups (frequency not specified).<br />

Hyper-responsiveness to stimulation with both GnRH and LH (10); blunted<br />

response to naloxone stimulation (10).<br />

Suppressed intratesticular sperm counts, sperm production rate, and serum<br />

testosterone in both Pb treated groups (10–10); sperm parameters and serum<br />

testosterone normalized at the end <strong>of</strong> the recovery period in the pre-pubertal animals<br />

(27 days at start) (10) but not in the pubertal animals (52 days at start) (5).<br />

Decreased sperm concentration, sperm production rate and suppressed serum<br />

testosterone concentrations after 14 days <strong>of</strong> exposure; not dose related (NS).<br />

Dose-related suppression <strong>of</strong> spermatogenesis (decreased sperm count and sperm<br />

production rate) in the exposed rats <strong>of</strong> the two highest age groups (p < 0.05); doserelated<br />

suppression <strong>of</strong> serum testosterone in 52-day old rats (p = 0.04) and in 70-day<br />

old rats (p < 0.003).<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB >200 µg/dL<br />

Chronic PbB


AX5-54<br />

Citation<br />

Sokol et al.<br />

(1985) †<br />

Sokol et al.<br />

(1994)<br />

Sokol et al.<br />

(2002)<br />

Thoreux-<br />

Manlay et al.<br />

(1995a)<br />

Thoreux-<br />

Manlay et al.<br />

(1995b)<br />

Wadi and<br />

Ahmad (1999)<br />

Wenda-<br />

Rózewicka<br />

et al. (1996)<br />

Yu et al.<br />

(1996)<br />

Table AX5-4.2 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Males<br />

Species/<br />

Strain/Age Dose/Route/Form/Duration Endpoint<br />

Rat/Wistar,<br />

52 days old<br />

Rat/Sprague-<br />

Dawley,<br />

100 days old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, 97 days<br />

old<br />

Rat/Sprague-<br />

Dawley, adult<br />

Mouse/CF-1,<br />

adult<br />

Rat/Wistar,<br />

adult<br />

Rat/Sprague-<br />

Dawley,<br />

neonates<br />

0.1 or 0.3% Pb acetate in<br />

drinking water <strong>for</strong> 30 days<br />

0.3% Pb acetate in drinking<br />

water <strong>for</strong> 14, 30, or 60 days<br />

Negative correlations between PbB levels and serum and intratesticular testosterone<br />

values; dose-dependent reduction in intratesticular sperm count; FSH values were<br />

suppressed; no change in LH; decrease in ventral prostatic weight; no difference in<br />

testicular or seminal vesicle weights.<br />

Pb exposed fertilized fewer eggs; increased duration <strong>of</strong> exposure did not result in more<br />

significant percentage <strong>of</strong> eggs not fertilized; no ultrastructural changes were noted in<br />

the spermatozoa <strong>of</strong> animals; no difference in histogram patterns <strong>of</strong> testicular cells.<br />

Pb acetate in water <strong>for</strong> 1 wk Dose-related increase in gonadotropin-releasing hormone (GnRH) mRNA; no effect<br />

on the serum concentrations <strong>of</strong> hypothalamic gonadotropin-releasing hormone (GnRH)<br />

or LH.<br />

0–8 mg Pb acetate/kg i.p. <strong>for</strong><br />

5 days/wk, 35 days<br />

8 mg/kg-d Pb <strong>for</strong> 5 days/wk,<br />

35 days<br />

0.25 and 0.5% Pb acetate in<br />

drinking water <strong>for</strong> 6 wks<br />

1% aqueous solution <strong>of</strong> Pb<br />

acetate <strong>for</strong> 9 mo<br />

Neonatal and lactational<br />

exposure to 0.3% Pb acetate<br />

in drinking water beginning<br />

PND 1 to PND 21<br />

*Not including effects on the nervous or immune systems.<br />

† Candidate key study.<br />

No effects on spermatogenesis; decreased plasma and testicular testosterone by 80%;<br />

decreased plasma LH by 32%, indications <strong>for</strong> impaired Leydig cell function, no effects<br />

on fertility.<br />

Germ cells and Sertoli cells were not major target <strong>of</strong> Pb, accessory sex glands were<br />

target; epididymal function was unchanged; plasma and testicular testosterone dropped<br />

about 80%, plasma LH only dropped 32%.<br />

Low dose significantly reduced number <strong>of</strong> sperm within epididymis; high dose reduced<br />

both the sperm count and percentage <strong>of</strong> motile sperm and increased the percentage <strong>of</strong><br />

abnormal sperm within the epididymis; no significant effect on testis weight, high dose<br />

significantly decreased the epididymis and seminal vesicles weights as well as overall<br />

body weight gain; LH, FSH, and testosterone were not affected.<br />

Electron microscopic studies did not reveal any ultrastructural changes in the<br />

semiferous epithelium or in Sertoli cells; macrophages <strong>of</strong> testicular interstitial tissue<br />

contained (electron dense) Pb-loaded inclusions, usually located inside phagolisosomelike<br />

vacuoles; x-ray micro-analysis revealed that the inclusions contained Pb.<br />

Neonatal exposure to Pb decreased cold-water swimming endurance (a standard test <strong>for</strong><br />

stress endurance) and delayed onset <strong>of</strong> puberty in males and female <strong>of</strong>fspring, which<br />

was exacerbated by swimming stress.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB 34 ± 3 µg/dL or<br />

PbB 60 ± 4 µg/dL<br />

PbB ~40 µg/dL<br />

PbB 12–28 µg/dL<br />

PbB not reported<br />

PbB 1700 µg/dL<br />

PbB not reported<br />

PbB not reported<br />

PbB 70 µg/dL<br />

3ß-HSD, 3ß-hydroxysteriod dehydrogenase; dbcAMP, dibutyryl cyclic adenosine-3',5'-monophosphate; DTT, dithiothreitol; FSH, follicle stimulating hormone; G6PDH, glucose-6-phosphate<br />

dehydrogenase; GD, gestational day; GnRH, gonadotropin releasing hormone; hCG, human chorionic gonadotropin; IGF1, insulin-like growth factor 1; i.p., intraperitoneal; LDH, lactate<br />

dehydrogenase; LH, luteinizing hormone; LHRH, luteinizing hormone releasing hormone; LPP, lipid peroxidation potential; NCD, nuclear chromatin decondensation rate; NOS, not otherwise<br />

specified; PbB, blood lead concentration; PND, post-natal day; p.o., per os (oral administration); ROS, reactive oxygen species; SDH, succinic acid dehydrogenase; SOPR, sperm-oocyte penetration<br />

rate; StAR, steroidogenic acute regulatory protein; VC, vitamin C; VE, vitamin E; VMA, vanilmandelic acid


AX5-55<br />

Citation<br />

Burright et al.<br />

(1989)<br />

C<strong>of</strong>figny et al.<br />

(1994) †<br />

Corpas et al.<br />

(2002a)<br />

Cory-Slechta<br />

et al. (2004) †<br />

Dearth et al.<br />

(2002) †<br />

Dearth et al.<br />

(2004)<br />

Table AX5-4.3. Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Females<br />

Species/<br />

Strain/Age<br />

Mouse/HET,<br />

neonates<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Wistar,<br />

adult<br />

Rat/Long-Evans,<br />

adult<br />

Rat/Fisher 344,<br />

150–175 g<br />

Rat/Sprague-<br />

Dawley and<br />

Fisher-344,<br />

adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

0.5% Pb acetate solution via<br />

milk, or drinking water<br />

chronic beginning PND 1<br />

Inhalation exposure to<br />

5 mg/m 3 Pb oxide daily <strong>for</strong><br />

13 days during gestation<br />

(GD 2, 3, 6–10, 13–17, 20)<br />

300 mg/L acetate Pb in<br />

drinking water from mating<br />

until PND 12 or PND 21<br />

Pb acetate in drinking water<br />

beginning 2 mo be<strong>for</strong>e<br />

breeding through weaning<br />

12 mg/mL Pb acetate gavage<br />

from 30 days prior breeding<br />

until pups were weaned<br />

21 days after birth; 10–<br />

32 litters per group, control<br />

group, gestation and lactation<br />

exposure, gestation only<br />

exposure, lactation only<br />

exposure<br />

12 mg/mL Pb acetate by<br />

gavage 30 days prior to<br />

breeding through PND 21<br />

(gestation and lactation<br />

exposure)<br />

Plasma prolactin levels implied that Pb exposure alone decreased circulating prolactin<br />

in primiparous; low prolactin levels in non-behaviorally tested females suggests that<br />

dietary Pb alone may alter plasma-hormone in these lactating HET dams; pattern <strong>of</strong><br />

plasma prolactin appear to be inconsistent with the observation that Pb exposure<br />

decreases dopamine; prolactin levels <strong>of</strong> Pb exposed dams were very low.<br />

No effects on the incidence <strong>of</strong> pregnancy, prenatal death, or mal<strong>for</strong>mations when male<br />

and female rats from mothers who had been exposed.<br />

Neither abnormalities in the liver structure nor depositions <strong>of</strong> Pb, toxicant produced<br />

biochemical alterations; pups exhibited decrease in hemoglobin, iron and alkaline, and<br />

acid phosphatase levels and an increase in Pb content; protein, DNA, and lipid total<br />

amounts were reduced, and hepatic glycogen content was diminished at 12 and 21 PN,<br />

with a higher dose <strong>of</strong> glucose in blood; decrease in alkaline phosphatase in liver <strong>of</strong> pups<br />

at day 21 PN, but acid phosphatase was unaltered.<br />

Observed potential effects <strong>of</strong> Pb and stress in female; Pb alone (in male) and Pb plus<br />

stress (in females) permanently elevated corticosterene levels in <strong>of</strong>fspring.<br />

Delay in onset <strong>of</strong> puberty (p < 0.05); reduced serum levels <strong>of</strong> IGF1 (p < 0.001), LH<br />

(p < 0.001), and E2 (p < 0.001).<br />

Pb delayed the timing <strong>of</strong> puberty in PbB 37.3 µg/dL Pb group and suppressed serum<br />

levels <strong>of</strong> LH and E2, these effects did not occur in PbB 29.9 µg/dL Pb group, when<br />

doubling dose to 29.9 µg/dL group the PbB levels rose to 62.6 µg/dL, yet no effect was<br />

noted; results indicate that <strong>of</strong>fspring are more sensitive to maternal Pb exposure with<br />

regard to puberty related insults than are 29.9 µg/dL rats.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB ~100 µg/dL<br />

PbB 71.1 µg/dL (dam)<br />

PbB 83.2 µg/dL (fetal)<br />

PbB 22 µg/dL<br />

PbB 30–40 µg/dL<br />

Maternal PbB: ~40 µg/dL<br />

Pups PbB as follows:<br />

Gest+lact: ~38 µg/dL PND 10<br />

Gest+lact: ~15 µg/dL PND 21<br />

Gest+lact: ~3 µg/dL PND 30<br />

Gest: ~14 µg/dL PND 10<br />

Gest: ~3 µg/dL PND 21<br />

Gest: ~1 µg/dL PND 30<br />

Lact: ~28 µg/dL PND 10<br />

Lact: ~15 µg/dL PND 21<br />

Lact: ~3 µg/dL PND 30<br />

PbB 29.9 µg/dL (Sprague-<br />

Dawley)<br />

PbB 37.3 µg/dL (Fisher)


AX5-56<br />

Citation<br />

Table AX5-4.3 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Females<br />

Species/<br />

Strain/Age<br />

Foster (1992) Monkey/<br />

Cynomolgus,<br />

0–10 yrs old<br />

Foster et al.<br />

(1992)<br />

Foster et al.<br />

(1996b)<br />

Franks et al.<br />

(1989)<br />

Fuentes et al.<br />

(1996)<br />

Gorbel et al.<br />

(2002)<br />

Monkey/<br />

Cynomolgus,<br />

10 yrs old<br />

Monkey/<br />

Cynomolgus,<br />

15–20 yrs old<br />

Monkey/Rhesus,<br />

adult<br />

Mouse/Swiss,<br />

adult<br />

Rat/NOS,<br />

3 mo old<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

Daily dosing <strong>for</strong> up to 10 yrs<br />

with gelatin capsules<br />

containing Pb acetate<br />

(1.5 mg/kg); 8 control group<br />

monkeys, 8 lifetime exposure<br />

(birth–10 yrs), 8 childhood<br />

exposure (birth–400 days),<br />

and 8 adolescent exposure<br />

(postnatal day 300–10 yrs <strong>of</strong><br />

age)<br />

Daily dosing <strong>for</strong> up to 10 yrs<br />

with gelatin capsules<br />

containing Pb acetate<br />

(1.5 mg/kg); 8 control group<br />

monkeys, 8 childhood (birth–<br />

400 days), 7 adolescent<br />

(postnatal day 300–10 yrs),<br />

7 lifetime (birth–10 yrs)<br />

Chronic exposure to Pb<br />

acetate 50 to 2000 µg/kg-d<br />

p.o. beginning at birth <strong>for</strong><br />

15–20 yrs; 20 control<br />

monkeys, 4 monkeys in<br />

50 µg/kg-d group, 3 monkeys<br />

in 100 µg/kg-d, 2 monkeys in<br />

500 µg/kg-d group, and<br />

3 monkeys in 2000 µg/kg-d<br />

group<br />

Pb acetate in drinking water<br />

(2–8 mg/kg-d) <strong>for</strong> 33 mo; 7<br />

control and 10 Pb monkeys<br />

14, 28, 56, and 112 mg/kg Pb<br />

acetate via i.p; one time<br />

exposure on GD 9<br />

3 mg (P1) or 6 mg (P2) Pb<br />

acetate in drinking water <strong>for</strong><br />

15, 30, 45, 60, or 90 days<br />

Statistically significant reductions in circulating levels <strong>of</strong> LH (p < 0.042), FSH<br />

(p < 0.041), and E2 (p < 0.0001) during menstrual cycle; progesterone concentrations<br />

were unchanged and menstrual cycle was not significantly affected.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB


AX5-57<br />

Citation<br />

Iavicoli et al.<br />

(2004)<br />

Junaid et al.<br />

(1997)<br />

Laughlin et al.<br />

(1987)<br />

Lögdberg<br />

et al. (1987)<br />

Lögdberg<br />

et al. (1988)<br />

McGivern<br />

et al. (1991) †<br />

Nilsson et al.<br />

(1991)<br />

Piasek and<br />

Kostial(1991)<br />

Pinon-<br />

Lataillade<br />

et al. (1995)<br />

Table AX5-4.3 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Females<br />

Species/<br />

Strain/Age<br />

Mouse/Swiss,<br />

33–37 days old<br />

Mouse/Swiss,<br />

adult<br />

Monkey/Rhesus,<br />

adult<br />

Monkey/<br />

Squirrel, adult<br />

Monkey/<br />

Squirrel, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Mouse/NMRI,<br />

adult<br />

Rat/Wistar,<br />

10 wks old<br />

Mouse/NMRI,<br />

adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

0.02, 0.06, 0.11, 0.20, 2.00,<br />

4.00, 20.00, 40.00 ppm in<br />

food Pb acetate concentration<br />

beginning GD 1 to 3 mo after<br />

birth<br />

0, 2, 4, or 8 mg/kg-d Pb<br />

acetate, subchronic exposure,<br />

5 days/wk, 60 days<br />

Pb acetate in drinking water<br />

at 3.6, 5.9, or 8.1 mg/kg-d <strong>for</strong><br />

1–2 yrs; 7 control and 10<br />

experimental monkeys per<br />

group<br />

Pb acetate in drinking water<br />

from 9th week <strong>of</strong> gestation to<br />

PND 1; per oral exposure<br />

similar to Laughlin et al.<br />

(1987)<br />

Pb acetate maternal dosing<br />

from 5–8.5 wks pregnant to<br />

PND 1<br />

11 control monkeys, 3 low-<br />

Pb exposure group (PbB<br />

24 µg/dL), 7 medium Pb<br />

group (PbB 40 µg/dL, 5 high-<br />

Pb group (PbB 56 µg/dL)<br />

0.1% Pb acetate in drinking<br />

water from GD 14 to<br />

parturition<br />

75 µg/g bw Pb chloride via<br />

i.v.; one time injection on<br />

GD 4<br />

7500 ppm Pb acetate in<br />

drinking water <strong>for</strong> 9 wks<br />

0–0.5% Pb acetate in<br />

drinking water exposed to Pb<br />

during gestation until post-<br />

GD 60<br />

Increase in food consumption; however, did low-dose group increase food consumption<br />

because <strong>of</strong> sweet nature <strong>of</strong> Pb. Body weight may contribute to delay in onset <strong>of</strong> puberty<br />

and confound results.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB 0.69, 1.32, 1.58, 1.94, 3.46,<br />

3.80, 8.35, 13.20 µg/dL<br />

Altered follicular development. PbB 22.3–56.5 µg/dL<br />

Reductions in cycle frequency (p < 0.01); fewer days <strong>of</strong> flow (p < 0.01); longer and<br />

more variable cycle intervals (p < 0.025).<br />

Increase in pre- and perinatal mortality during the last two-thirds <strong>of</strong> pregnancy;<br />

statistically significant reduction in mean birth weight was observed in Pb exposed<br />

monkeys as compared to controls.<br />

Dose-dependent reduction in placental weight (p < 0.0007); various pathological lesions<br />

were seen in the placentas, including hemorrhages, hyalinization <strong>of</strong> the parenchyma<br />

with destruction <strong>of</strong> the villi, and massive vacuolization <strong>of</strong> chorion epithelium.<br />

Female rats showed delay in vaginal opening; 50% exhibited prolonged and irregular<br />

periods <strong>of</strong> diestrous and lack observable corpora lutea; both sexes showed irregular<br />

release patterns <strong>of</strong> both FSH and LH.<br />

Electron microscopy showed that the uterine lumen, which was closed in control mice,<br />

was opened in Pb-injected mice; suggested that Pb caused increase in uterine secretion;<br />

study suggested Pb could have a direct effect on the function <strong>of</strong> the uterine epithelium<br />

and that Pb was secreted into the uterine lumen and affect the blastocysts.<br />

Decrease in litter size, pup survival, and birth weight; food consumption, body weight,<br />

and fertility were not altered in 20 wk exposure period.<br />

PbB 44–89 µg/dL<br />

51.2 µg/dL (low dose)<br />

80.7 µg/dL (mid dose)<br />

88.4 µg/dL (high dose)<br />

Mean maternal PbB 54 µg/dL<br />

(39–82 µg/dL)<br />

PbB 37 µg/dL (22–82 µg/dL)<br />

24 (22–26) µg/dL (low dose)<br />

40 (35–46) µg/dL (mid dose)<br />

56 (43–82) µg/dL (high dose)<br />

PbB 73 µg/dL<br />

PbB not reported<br />

Maternal PbB >300 µg/dL<br />

Offspring PbB >220 µg/dL<br />

Exhibited reduced fertility as evidenced by smaller litters and fewer implantation sites. PbB 70 µg/dL


AX5-58<br />

Citation<br />

Priya et al.<br />

(2004)<br />

Ronis et al.<br />

(1996)<br />

Ronis et al.<br />

(1998a) †<br />

Ronis et al.<br />

(1998b)<br />

Ronis et al.<br />

(1998c)<br />

Sierra and<br />

Tiffany-<br />

Castiglioni<br />

(1992)<br />

Srivastava<br />

et al. (2004)<br />

Table AX5-4.3 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Females<br />

Species/<br />

Strain/Age<br />

Rat/Charles<br />

Foster,<br />

6–9 mo old<br />

Rat/Sprague-<br />

Dawley, various<br />

ages<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Guinea<br />

pig/NOS, adult<br />

Rat/Fisher 344,<br />

adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

0.03 µM Pb in vitro <strong>for</strong> 1 h LH binding was dropped to 84% in Pb treated cells; Pb exposed cells showed 31%<br />

reduction in the enzymes 17ß-HSDH and 17ß-HS; Pb can cause a reduction in LH and<br />

FSH binding, which significantly alters steroid production in vitro and exerts a direct<br />

influence on granulose cell function.<br />

Pb acetate in the drinking<br />

water or male and female rats<br />

<strong>for</strong> the following durations:<br />

PND 24–74 (pubertal<br />

exposure); PND 60–74<br />

(post pubertal exposure)<br />

0.6% Pb acetate in drinking<br />

water; ad libitum <strong>for</strong> various<br />

durations as follows: GD 5 to<br />

PND 1, GD 5 to weaning,<br />

PND 1 to weaning<br />

Ad libitum intake <strong>of</strong> Pb<br />

acetate (0.05 to 0.45% w/v);<br />

Pb exposure <strong>of</strong> dams until<br />

weaning, exposure <strong>of</strong> pups<br />

until day 21, 35, 55, 85<br />

0.05, 0.15, or 0.45% Pb<br />

acetate in drinking water<br />

beginning GD 5 <strong>for</strong> 21, 35,<br />

55, 85 days<br />

0, 5.5, or 11 mg/kg Pb<br />

acetate, oral dose from GD 22<br />

until GD 52 or 62<br />

12 mg/mL Pb acetate by<br />

gavage <strong>for</strong> 30 days prior to<br />

breeding until weaning<br />

Data suggest that both the temporary and the long-lasting effects <strong>of</strong> Pb on reproductive<br />

endpoints in male and female experimental animals are mediated by the effects <strong>of</strong> Pb on<br />

multiple points along the hypothalamic-pituitary-gonad axis; exposure <strong>of</strong> male and<br />

female Sprague-Dawley rats pre-pubertally (age 24–74 days) to Pb acetate in the<br />

drinking water resulted in significant reduction in testis weight and in the weight <strong>of</strong><br />

secondary sex organs in males; these effects were not observed in rats exposed postpubertally<br />

(day 60–74); there is convincing evidence that pre-pubertal female rats<br />

exposed in utero and during lactation have reduced levels <strong>of</strong> circulating E2 and LH.<br />

Female pups exposed to Pb from birth through adulthood or from GD 5 through<br />

adulthood were observed to have significantly delayed vaginal opening and disrupted<br />

estrus cycling; these effects on female reproductive physiology were not observed in<br />

animals where Pb exposure was confined only to pregnancy or lactation.<br />

Prenatal Pb exposure that continues until adulthood (85 days old) delays sexual<br />

maturation in female pups in a dose-related manner; dose-dependent delay in sexual<br />

maturation (delayed vaginal opening) among female rats following prenatal Pb<br />

exposure that continued until adulthood (85 days old); a growth hormone-mediated<br />

effect on growth that differs depends upon the developmental state <strong>of</strong> the animal birth<br />

weight was significantly reduced and more pronounced among male pups; decreased<br />

growth rates in both sexes were accompanied by a statistically significant decrease in<br />

plasma concentrations <strong>of</strong> IGF1 through puberty and a significant increase in pituitary<br />

growth hormone during puberty; growth suppression <strong>of</strong> male and female rats involves<br />

disruption <strong>of</strong> growth hormone secretion during puberty.<br />

Dose-responsive decrease in birth weight and crown-to-rump length was observed in<br />

litters; dose-dependent delay in sexual maturity (delay in vaginal opening); decrease in<br />

neonatal sex steroid levels and suppression <strong>of</strong> E2 during puberty; elevation in pituitary<br />

LH content was observed during early puberty; E2 cycle was significantly disrupted at<br />

the highest Pb dose; data suggests that the reproductive axis is particularly sensitive to<br />

Pb during specific developmental periods, resulting in delayed sexual maturation<br />

produced by sex steroid biosynthesis.<br />

Hypothalamic levels <strong>of</strong> SRIF; lower serum concentrations <strong>of</strong> progesterone at higher<br />

dose only; hypothalamic levels <strong>of</strong> GnRH and SRIF were reduced in a dose-dependent<br />

manner by Pb treatment in both dams and fetuses; reduction <strong>of</strong> SRIF levels in 52-days<br />

old fetus was particularly severe (92%) in the 11 mg group.<br />

Pb decreased StAR protein expression and lowered E2 levels; suggested that the<br />

primary action <strong>of</strong> Pb to suppress E2 is through its known action to suppress the serum<br />

levels <strong>of</strong> LH and not due to decreased responsiveness <strong>of</strong> StAR synthesizing machinery.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not applicable–in vitro study<br />

Maternal PbB 30–60 µg/dL<br />

Offspring PbB >200 µg/dL.<br />

Pups continuously exposed to Pb<br />

225 to 325 µg/dL<br />

Mean PbB in <strong>of</strong>fspring at 0.05%<br />

(w/v) 49 ± 6 µg/dL<br />

Mean PbB in <strong>of</strong>fspring at 0.15%<br />

(w/v) 126 ± 16 µg/dL<br />

Mean PbB in <strong>of</strong>fspring at 0.45%<br />

(w/v) 263 ± 28 µg/dL<br />

PbB in dams 181 ± 14 µg/dL<br />

PbB in pups ranged from 197 ±<br />

82 to 263 ± 38 µg/dL, increasing<br />

with age <strong>of</strong> pups<br />

PbB not reported<br />

PbB <strong>of</strong> dams 39 ± 3.5 SEM<br />

µg/dL and <strong>of</strong>fspring PbB 2.9 ±<br />

0.28 SEM µg/dL


AX5-59<br />

Citation<br />

Taupeau et al.<br />

(2001)<br />

Tchernitchin<br />

et al. (1998a)<br />

Tchernitchin<br />

et al. (1998b)<br />

Table AX5-4.3 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Reproduction and Development in Mammals Effects on Females<br />

Species/<br />

Strain/Age<br />

Mouse/C57blxC<br />

BA, 8 wks old<br />

Rat/Sprague-<br />

Dawley, 14 days<br />

old<br />

Rat/Sprague-<br />

Dawley, 20 or<br />

21 days old<br />

Wide (1985) Mouse/NMRI,<br />

10 wks old<br />

Wide and<br />

D'Argy (1986)<br />

Wiebe and<br />

Barr (1988)<br />

Wiebe et al.<br />

(1988)<br />

Yu et al.<br />

(1996)<br />

Mouse/NMRI,<br />

adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Rat/Sprague-<br />

Dawley, adult<br />

Dose/Route/<br />

Form/Duration Endpoint<br />

10 mg/kg-d Pb nitrate via i.v.<br />

<strong>for</strong> 15 days<br />

172 µg/g bw Pb from day 14<br />

every 2nd day until day 20<br />

(75 mg/g bw) Pb via i.v. one<br />

time exposure at 1 or<br />

24 be<strong>for</strong>e hormone<br />

stimulation<br />

20 µg/dL/g bw Pb chloride<br />

via i.v. single exposure on<br />

days 8, 12, or 16 after mating<br />

20 µg/g bw by i.v. single<br />

injection on GD 8<br />

20 or 200 ppm Pb chloride in<br />

drinking water; 3 exposure<br />

durations; prior to mating<br />

through weaning, GD 7 to<br />

weaning, PND 21 to PND 35<br />

20 or 200 ppm Pb chloride in<br />

drinking water; 4 exposure<br />

durations; prior to mating<br />

through weaning, GD 7 to<br />

weaning, PND 21 to PND 35,<br />

prior to mating only<br />

Neonatal and lactational<br />

exposure to 0.3% Pb acetate<br />

in drinking water (PND 30)<br />

Low Pb concentration in the ovary caused dysfunction <strong>of</strong> folliculogenesis, with fewer<br />

primordial follicles and an increase in atretic antral follicles.<br />

Pb inhibits estrogen-induced uterine eosinophilia at 6 and 24 hr after treatment; Pb also<br />

inhibits estrogen-induced edema in deep and superficial endometrial stoma at 24 hr but<br />

not 6 hr after treatment; myometrial hypertrophy is inhibited under the effect <strong>of</strong> exposure<br />

at 24 hr <strong>of</strong> treatment.<br />

Enhanced some parameters <strong>of</strong> estrogen stimulation and inhibited other estrogenic<br />

responses; interaction with responses to estrogen was different depending on whether Pb<br />

pretreatment was 1 or 24 hr be<strong>for</strong>e hormone stimulation; estrogenic responses mostly<br />

affected were uterine eosinophilia, endometrial edema, uterine liminal epithelial,<br />

hypertrophy, and mitosis in various, but not all, uterine cell types, in some cell types,<br />

estrogen-induced mitotic response developed earlier under the effect <strong>of</strong> Pb exposure.<br />

Litter size and fetal survival varied significantly; small litters and increased numbers <strong>of</strong><br />

fetal deaths were observed in mice exposed to Pb on day 8 <strong>of</strong> intrauterine life; live fetuses<br />

were normal with respect to weight and morphological appearance; ovarian follicle<br />

counts revealed a significantly smaller number <strong>of</strong> primordial follicles in the latter group,<br />

it suggested that the exposure to Pb at a time <strong>of</strong> early organogenesis caused the observed<br />

fertility decrease by interfering with the development <strong>of</strong> the female germ cells.<br />

Primordial germ cells showed a normal body distribution but were significantly fewer at<br />

all four stages compared with those <strong>of</strong> control embryos <strong>of</strong> corresponding age; Pb had<br />

interfered with the production or activity <strong>of</strong> alkaline phosphatase.<br />

Treatment with Pb prior to mating resulted in significant increase in E2-receptor affinity<br />

in 21-day old <strong>of</strong>fspring without a change in E2 receptor number; treatment from day 7 <strong>of</strong><br />

pregnancy until weaning <strong>of</strong> the pups resulted in ~35% decrease in E2 receptors per mg<br />

uterine protein when these <strong>of</strong>fspring reached 150 days <strong>of</strong> age; Pb treatment from 21–35<br />

days old or until 150 days resulted in a significant decrease in uterine E2 receptor number<br />

at 35 and 150 day, respectively.<br />

Exposure to Pb did not affect tissue weights but did cause a significant decrease in<br />

gonadotropin-receptor binding in the pre-pubertal, pubertal, and adult females;<br />

conversion <strong>of</strong> progesterone to androstenedione and dihydrotestosterone was significantly<br />

decreased in 21-day old rats and in 150-day old females; significantly increased<br />

conversion to the 5-alpha-reduced steroids, normally high during puberty.<br />

Neonatal exposure to Pb decreased cold-water swimming endurance (a standard test <strong>for</strong><br />

stress endurance); delayed onset <strong>of</strong> puberty in males and female <strong>of</strong>fspring, which was<br />

exacerbated by swimming stress.<br />

Blood <strong>Lead</strong> Concentration<br />

(PbB)<br />

PbB not reported<br />

PbB 47 µg/dL<br />

PbB not reported<br />

PbB not reported<br />

PbB not reported<br />

PbB likely 4.0 ± 1.4 to 6.6 ±<br />

2.3 µg/dL (similar design as<br />

Wiebe et al. (1988)<br />

PbB range 4.0 ± 1.4 to 6.6 ±<br />

2.3 µg/dL<br />

PbB 70 µg/dL<br />

*Not including effects on the nervous or immune systems.<br />

†<br />

Candidate key study.<br />

E2, estradiol; FSH, follicle stimulating hormone; GD, gestational day; GnRH, gonadotropin releasing hormone; HET, Binghamton Heterogeneous Stock; IGF1, insulin-like growth factor 1;<br />

i.p., intraperitoneal; LH, luteinizing hormone; NOS, not otherwise specified; PbB, blood lead concentration; PND, post-natal day; p.o., per os (oral administration); SRIF, somatostatin; StAR,<br />

steroidogenic acute regulatory protein.


ANNEX TABLES AX5-5<br />

AX5-60


AX5-61<br />

Table AX5-5.1. In Vivo and In Vitro Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Production and Metabolism <strong>of</strong> Reactive<br />

Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease<br />

Reference<br />

Khalil-<br />

Manesh et al.<br />

(1994)<br />

Gonick et al.<br />

(1997)<br />

Ding et al.<br />

(1998)<br />

Pb Exposure Measured Parameters<br />

Species/<br />

Tissue Age/Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD<br />

rats<br />

Male SD<br />

rats<br />

Male SD<br />

rats<br />

Vaziri (1997) Male SD<br />

rats<br />

Dursun<br />

(2005)<br />

Male SD<br />

rats<br />

200 g N/A Pb-acetate,<br />

100 ppm in<br />

water<br />

2 mo<br />

200 g<br />

6 Pb-acetate,<br />

100 ppm in<br />

water<br />

2 mo N/A Pb-acetate,<br />

100 ppm in<br />

water<br />

190 g 12 Pb-acetate,<br />

100 ppm in<br />

water<br />

24 Pb acetate<br />

8 mg/kg IP<br />

6 mo 7 ± 3.6 µg/d BP, tail art.<br />

ring response<br />

to NE<br />

3 mo 12.4 ± 1.8 µg/dL BP cGMP, NO2 +<br />

NO3, ET-1,<br />

ET-3, MDA,<br />

eNOS, iNOS<br />

3 mo 3.2 ± 0.2 µg/dL BP Urine NO2 +<br />

NO3, plasma<br />

MDA<br />

3 mo 17 ± 9 µg/dL BP Plasma MDA<br />

urine NO2 +<br />

NO3<br />

2 wks BP, RBF Ur Na, Ur<br />

NO2 + NO3,<br />

24 hr UrNa<br />

(Na + intake<br />

Not given )<br />

ET-3, cGMP DMSA RX Pb caused HTN, ↑ET3,<br />

↓U cGMP (NS) (no<br />

effect on NE reactivity).<br />

DMSA Rx lowered BP<br />

and Vasc response to NE<br />

and raised cGMP<br />

— HTN, ↑MDA, ↑eNOS,<br />

↑iNOS (protein and<br />

activity in kidney)<br />

DMSA (0.5% H2O)<br />

H 2 wks, i.v.<br />

infusions <strong>of</strong> L.<br />

Arg., SOD and SNP<br />

Antioxidant Rx<br />

(Lazaroid)<br />

Pb caused HTN, ↓urine<br />

NO2+NO3, ↑plasma<br />

MDA. DMSA lowered<br />

BP, blood Pb and MDA<br />

+ raised urine NO2 +<br />

NO3. L-Arg lowered BP<br />

and MDA, raised<br />

NO2+NO3, SNP lowered<br />

BP<br />

Pb caused HTN, ↑MDA,<br />

↓urine NO2+NO3 in<br />

untreated animals.<br />

Antioxidant Rx improved<br />

HTN, urine NO2 + NO3<br />

and lowered MDA<br />

without changes in blood<br />

Pb level<br />

↑BP, ↓RBF, ↓UrNO2 +<br />

NO3, unchanged UrNa +


AX5-62<br />

Table AX5-5.1 (cont’d). In Vivo and In Vitro Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Production and Metabolism <strong>of</strong><br />

Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease<br />

Reference<br />

Vaziri et al.<br />

(1999b)<br />

Vaziri et al.<br />

(2001)<br />

Vaziri and<br />

Ding (2001)<br />

Pb Exposure Measured Parameters<br />

Species/<br />

Tissue Age/Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD<br />

rats<br />

Male SD<br />

rats<br />

Human<br />

coronary<br />

endothelial<br />

cells<br />

200 g 6 per group<br />

per time point<br />

Pb-acetate,<br />

100 ppm in<br />

water<br />

3 mo 8.2 ± .8 and<br />

10.8 ± 1 µg<br />

per g. Kidney<br />

tissue in<br />

untreated and<br />

antiox-treated<br />

groups<br />

BP Aorta and<br />

kidney eNOS<br />

protein<br />

abundance, Ur<br />

NO2 + NO<br />

200 g 6 per group Pb acetate 3 mo N/A BP Aorta, heart,<br />

kidney and brain<br />

NOS iso<strong>for</strong>ms,<br />

urine NO2 +<br />

NO3<br />

N/A $4 per<br />

experiment<br />

0 and 1 ppm<br />

Pb acetate<br />

24 hrs w/Pb<br />

or Na acetate<br />

followed<br />

by 24 hrs<br />

w/tempol or<br />

vehicle<br />

1 ppm medium N/A eNOS<br />

expression<br />

Subgroups<br />

treated with highdose<br />

vitamin E<br />

Subgroups<br />

studied after 2<br />

wks <strong>of</strong> Rx<br />

w/tempol and<br />

those studied 2<br />

wks after<br />

cessation <strong>of</strong><br />

tempol Rx<br />

Co-treatment<br />

•<br />

w/O2 scavenger,<br />

tempol<br />

Pb exposure resulted in a<br />

time-dependent rise in<br />

BP, aorta and kidney<br />

eNOS and iNOS. This<br />

was associated w/a<br />

paradoxical fall in NO<br />

availability (Ur NO2 ±<br />

NO3). Antioxidant Rx<br />

attenuated upregulation<br />

<strong>of</strong> iNOS and eNOS and<br />

raised NO availability.<br />

Pb exposure resulted in<br />

rises in BP, eNOS, iNOS<br />

and nNOS in the tested<br />

tissues + ↓urine NOx.<br />

Tempol administration<br />

attenuated HTN, reduced<br />

NOS expressions and<br />

increased urine NOx.<br />

The effects <strong>of</strong> tempol<br />

disappeared within 2 wks<br />

<strong>of</strong> its discontinuation.<br />

Pb exposure <strong>for</strong> 48 hr<br />

upregulated eNOS<br />

expression. Co-treatment<br />

w/ tempol resulted in<br />

dose-dependent reversal<br />

<strong>of</strong> Pb-induced<br />

upregulation <strong>of</strong> eNOS<br />

but had no effect on<br />

control cells.


AX5-63<br />

Table AX5-5.1 (cont’d). In Vivo and In Vitro Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Production and Metabolism <strong>of</strong><br />

Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease<br />

Reference<br />

Vaziri et al.<br />

(1999a)<br />

Vaziri et al.<br />

(2003)<br />

Ni et al.<br />

(2004)<br />

Pb Exposure Measured Parameters<br />

Species/<br />

Tissue Age/Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD rats 200 g 6 per group 100 ppm in<br />

water<br />

Male SD rats 200 g 6 per group 100 ppm in<br />

water<br />

Cultured<br />

human<br />

coronary<br />

endothelial and<br />

VSM cells.<br />

N/A $4 per<br />

experiment<br />

0,1 and 10<br />

ppm Pb<br />

acetate<br />

3 mo 8.3–10.8 µg/g<br />

kidney tissue<br />

BP Urine NO2 +<br />

NO3, tissue and<br />

plasma<br />

nitrotyrosine<br />

(marker <strong>of</strong><br />

NO-ROS<br />

interaction).<br />

3 mo N/A BP Urine NO2 +<br />

NO3, kidney,<br />

heart, brain<br />

SOD, catalase,<br />

GPX, NAD(P)H<br />

oxidase<br />

abundance<br />

Short<br />

exposure<br />

(5–30 min)<br />

and long<br />

exposure<br />

(60 hr)<br />

0, 1, 10 ppm N/A<br />

•<br />

O2 and H2O2<br />

productions<br />

SOD, catalase,<br />

GPX and<br />

NAD(P)H<br />

oxidase<br />

(gp91 phox )<br />

Antioxidant Rx<br />

(Vit E)<br />

•<br />

Tempol (O2<br />

scavenger<br />

infusion)<br />

Pb exposure raised BP,<br />

reduced Ur NO2 + NO3<br />

and increased<br />

nitrotyrosine abundance<br />

in plasma, heart, kidney,<br />

brain and liver. Anti ox<br />

Rx ameliorated HTN,<br />

lowered nitrotyrosine and<br />

raised Ur NO2 + NO3.<br />

Pb caused HTN,<br />

↑NAD(P)H oxidase<br />

(gp91 phox ), ↑SOD, unchanged<br />

catalase and<br />

GPX, ↓UrNO2 + NO3.<br />

Tempol resulted in ↓BP<br />

+ ↑urine NO2 + NO3 in<br />

Pb-exposed but not<br />

control rats.<br />

None Short-term incubation<br />

with Pb at 1 and 10 ppm<br />

•<br />

raised O2 and H2O2<br />

productions by both<br />

endothelial and VSM<br />

cells, long-term<br />

incubation resulted in<br />

further rise in H2O2<br />

generation and<br />

normalization <strong>of</strong><br />

detectable O2y<br />

• . This was<br />

associated with increases<br />

in NAD(P)H oxidase and<br />

SOD and reduced or<br />

unchanged catalase and<br />

GPX.


AX5-64<br />

Table AX5-5.1 (cont’d). In Vivo and In Vitro Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Production and Metabolism <strong>of</strong><br />

Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease<br />

Reference<br />

Ding et al.<br />

(2001)<br />

Ding et al.<br />

(2000)<br />

Pb Exposure Measured Parameters<br />

Species/<br />

Tissue Age/Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD rats 2 mo<br />

200 g<br />

Cultured rat<br />

aorta<br />

endothelial<br />

cells<br />

Attri (2003) Male Wistar<br />

Kyoto rats<br />

Malvezzi<br />

(2001)<br />

Male Wistar<br />

rats<br />

N/A $4<br />

experiment<br />

150–200 g<br />

5–6 wks<br />

(170 g)<br />

N/A 100 ppm 3 mo Blood Pb 12.4 ±<br />

1.8 µg/dL vs. 1<br />

mg/dL in<br />

controls<br />

10 per<br />

group<br />

4–10 per<br />

group<br />

0–1 ppm 1, 2, 24, 84 hr 0–1 ppm culture<br />

media<br />

Pb acetate,<br />

100 ppm in<br />

water ±<br />

Vit C 20<br />

mg/d/rat<br />

Pb acetate<br />

750 ppm in<br />

water<br />

1–3 mo<br />

Blood Pb<br />

1.5 mg/dL at<br />

1 mo<br />

2.4 mg/dL at<br />

2 mo<br />

4.1 mg/dL at<br />

3 mo<br />

100 days Blood, bone,<br />

kidney, aorta,<br />

liver<br />

BP Response to<br />

DMTU<br />

administration,<br />

tissue<br />

nitrotyrosine,<br />

hydroxyl radical<br />

N/A Hydroxyl radical<br />

production using<br />

the following<br />

reaction (Na<br />

Salicylate + OH<br />

→ 2,3dihydroxy<br />

benzoic acid),<br />

MDA<br />

BP Total antioxidant<br />

capacity, ferricreducing<br />

antioxidant<br />

power, NO<br />

metabolites,<br />

MDA,<br />

8-hydroxyguano<br />

sine<br />

i.v. infusion <strong>of</strong><br />

DMTU<br />

Pb caused HTN, ↑plasma<br />

nitrotyrosine,<br />

↑plasma.OH<br />

concentration all reversed<br />

with .OH-scavenger,<br />

DMTU infusion<br />

None Pb exposure resulted in<br />

conc-dependent rise in<br />

MDA and OH<br />

production by cultured<br />

endothelial cells.<br />

Response to<br />

vitamin C.<br />

BP — Response to L.<br />

arg, DMSA, L.<br />

arg .+ DMSA<br />

(given together<br />

w/Pb in last<br />

30 days<br />

Pb caused ↑BP, ↑MDA,<br />

↑DNA damage/<br />

oxidation, ↓NOx,<br />

↓antioxidant and ferricreducing<br />

antioxidant.<br />

Concomitant Rx with Vit-<br />

C ameliorated all<br />

abnormalities.<br />

↑BP w/Pb, partial ↓BP<br />

w/L. Arg or DMSA,<br />

greater reduction w/both,<br />

blood and aorta PB<br />

remained ↑ in all but<br />

DMSA + L. Arg group.<br />

Significant Pb<br />

mobilization shown in<br />

other organs.


AX5-65<br />

Table AX5-5.1 (cont’d). In Vivo and In Vitro Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Production and Metabolism <strong>of</strong><br />

Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease<br />

Reference<br />

Khalil-<br />

Manesh et al.<br />

(1993b)<br />

Marques et al.<br />

(2001)<br />

Farmand et al.<br />

(2005)<br />

Courtois et al.<br />

(2003)<br />

Pb Exposure Measured Parameters<br />

Species/<br />

Tissue Age/Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD<br />

rats<br />

Male<br />

Wistar rats<br />

Male SD<br />

rats<br />

Rat<br />

thoracic<br />

aorta<br />

8 wks N/A Pb acetate 100 or<br />

5000 ppm in<br />

water<br />

3 mo 20 Pb acetate 5 ppm<br />

± Vit C (3<br />

mmol/L) in<br />

water<br />

200 g 8 Pb acetate 100<br />

ppm in water<br />

N/A 6/<br />

experiment<br />

1–12 mo 29 ± 4 µg/dL BP, vascular<br />

contractility to<br />

NE in vitro<br />

30 days N/A BP, arch-, SNPvasorelaxation<br />

response in aorta<br />

rings<br />

cGMP, ET-3, ANP — Pb caused HTN,<br />

↓serum and urine<br />

cGMP, ↑serum ET-3<br />

without changing ANP<br />

or response to NE<br />

sGC protein mRNA<br />

and activity.<br />

cGMP production,<br />

eNOS protein<br />

3 mo N/A BP Aorta sGC, SOD,<br />

catalase,<br />

glutathione<br />

peroxidase<br />

0–1 ppm 24 hr 0–1 ppm cGMP<br />

production<br />

sGC expression,<br />

superoxide<br />

production, COX-2<br />

CoTx with Vit C Pb caused HTN,<br />

↓relaxation to Ach and<br />

SNP, ↑eNOS, ↓sGC<br />

protein mRNA and<br />

activity. These<br />

abnormalities were<br />

prevented by<br />

antioxidant Rx.<br />

Vit C, COX-2<br />

inhibitor<br />

— ↓sGC, ↑CuZn SOD<br />

activity, unchanged<br />

catalase and GPX<br />

activities.<br />

Pb caused ↓sGC,<br />

↓cGMP, ↑O2, ↑COX-2.<br />

All abnormalities<br />

improved by Vit C.<br />

COX-2 inhibitor<br />

improved sGC<br />

expression but not O2<br />

production.


AX5-66<br />

Reference<br />

Watts et al.<br />

(1995)<br />

Rodríguez-<br />

Iturbe et al.<br />

(2005)<br />

Table AX5-5.2. Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on PKC Activity, NFkB Activation, and Apoptosis<br />

Species/<br />

Tissue<br />

Isolated rabbit<br />

mesenteric<br />

artery<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

N/A 5–6 sets per<br />

experiment<br />

Male SD rats 200 g 8 Pb group<br />

9 controls<br />

Pb acetate<br />

10 −10 −10 −3 M<br />

Pb acetate<br />

100 ppm in<br />

drinking<br />

water<br />

Immediate<br />

(contraction)<br />

5 −10 −10 −3 M<br />

medium<br />

Vascular<br />

contraction<br />

3 mo N/A NFkB activation,<br />

apoptosis, Ang <strong>II</strong><br />

positive cells,<br />

macrophage/T cell<br />

infiltration and<br />

nitrotyrosine staining<br />

in renal tissue<br />

Preincubation<br />

w/PKC<br />

activators, PKC<br />

inhibitor or<br />

verapamil <strong>for</strong><br />

30–60 min +<br />

endothelium<br />

denudation<br />

Pb acetate induced<br />

contraction which was<br />

potentiated by PKC<br />

activators and<br />

attenuated by PKC<br />

inhibitor (role <strong>of</strong><br />

PKC). CCB<br />

attenuated Pb-induced<br />

contraction<br />

(contribution <strong>of</strong> Ca 2+<br />

entry). Removal <strong>of</strong><br />

endothelium did not<br />

affect Pb-induced<br />

vasoconstriction.<br />

Pb-exposed animals<br />

showed<br />

tubuloniterstitial<br />

accumulation <strong>of</strong><br />

activated T-cells,<br />

macrophages and Ang<br />

<strong>II</strong> positive cells, NFkB<br />

activation increased<br />

apoptosis and<br />

nitrotyrosine staining<br />

in the kidney.


AX5-67<br />

Reference<br />

Chang et al.<br />

(1997)<br />

Tsao et al.<br />

(2000)<br />

Carmignani<br />

et al. (2000)<br />

Table AX5-5.3. Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Blood Pressure and Adrenergic System<br />

Species/<br />

Tissue<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Reference Species/Tissue<br />

Wistar rats 190–200 g 20 Pb acetate<br />

0.5% in<br />

drinking<br />

water<br />

Wistar rats 190–200 g 70 Pb acetate<br />

0–2% in<br />

drinking<br />

water<br />

2 mo Blood 29.1 ±<br />

1.9 µg/dL<br />

aorta; 1.9 ±<br />

0.2 µg/g<br />

2 mo Blood, heart,<br />

aorta, kidney<br />

Male SD rats 3 mo 24 60 ppm 10 mo Blood 22.8 ±<br />

1.2 µg/dL<br />

BP Plasma<br />

catecholamines +<br />

aorta; β receptor<br />

binding assay and<br />

cAMP generation<br />

BP, β agoniststimulated<br />

cAMP<br />

production<br />

(10 µM<br />

isoproterenol<br />

in vitro)<br />

BP, HR,<br />

cardiac<br />

contractility<br />

(dP/dt), blood<br />

flow<br />

pl NEpi, cAMP β<br />

receptor densities<br />

Plasma NE, Epi,<br />

dopamine, monoamine<br />

oxidase (MAO)<br />

activity, histology<br />

— Pb exposure caused<br />

HTN, elevated plasma<br />

NE (unchanged<br />

plasma Epi).<br />

↓ isoproterenolstimulated<br />

plasma<br />

cAMP, ↓ β receptor<br />

density in aorta.<br />

— Pb exposure raised BP<br />

and pl NE + lowered<br />

aorta and heart β<br />

receptor density, basal<br />

and stimulated cAMP<br />

productions +<br />

increased kidney β<br />

receptor density and<br />

basal and stimulated<br />

cAMP productions.<br />

— Pb exposure raised BP<br />

and dp/dt, lowered<br />

carotid blood flow, (no<br />

change in HR) raised<br />

plasma NE and Epi<br />

and MAO (all tissues)<br />

lowered plasma NOx<br />

+ ↓aorta media<br />

thickness,<br />

↑lymphocyte<br />

infiltration in<br />

periaortic fat,<br />

nonspecific change in<br />

kidney (congestion,<br />

edema, rare prox.<br />

tubular cell necrosis).


AX5-68<br />

Reference<br />

Lai et al.<br />

(2002)<br />

Chang et al.<br />

(2005)<br />

Table AX5-5.3 (cont’d). Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Blood Pressure and Adrenergic System<br />

Species/<br />

Tissue<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD rats 300 g Acute<br />

response<br />

Male Wistar<br />

rats<br />

In vivo:<br />

Intrathecal<br />

injection <strong>of</strong><br />

PbCl2, 10–<br />

100 µM.<br />

In vitro:<br />

Thoracic cord<br />

slices exposed<br />

to 5–50 µM<br />

PbCl2<br />

10 wks 70 2% Pb acetate<br />

(drinking<br />

water)<br />

— — BP, HR, (In vivo)<br />

w/without<br />

ganglionic blockade<br />

(Hexomethonium)<br />

2 mo,<br />

observed <strong>for</strong><br />

7 mo after<br />

cessation<br />

Blood:<br />

85 µg/dL<br />

Aorta:<br />

8 µ/g/g<br />

Heart:<br />

1 µg/g<br />

Kidney:<br />

60 µg/g<br />

Electophysiologi<br />

c measures (In<br />

vitro)<br />

be<strong>for</strong>e/after<br />

saline washout<br />

BP Plasma NE, β<br />

recaptor density<br />

(aorta, heart,<br />

kidney)<br />

— In vivo: IT injection<br />

<strong>of</strong> PbCl2 raised BP<br />

and HR. This was<br />

reversed by ganglionic<br />

blockade. In vitro: Pb<br />

raised excitatory and<br />

lowered inhibitory<br />

postsynaptic potentials<br />

which were reversed<br />

by removal <strong>of</strong> Pb<br />

(saline washout)<br />

Cessation <strong>of</strong> Pb<br />

exposure<br />

Pb exposure raised<br />

BP, plasma NE, and<br />

renal tissue β receptor<br />

and lowered<br />

aorta/heart β receptor<br />

density. Plasma and<br />

tissue Pb fell to nearcontrol<br />

values within 7<br />

mo. after Pb cessation.<br />

This was associated<br />

with significant<br />

reductions (not<br />

normalization) <strong>of</strong> BP,<br />

plasma NE and partial<br />

correction <strong>of</strong> tissue β<br />

receptor densities<br />

(Bone Pb was not<br />

measured).


AX5-69<br />

Reference<br />

Carmignani<br />

et al. (1999)<br />

Sharifi et al.<br />

(2004)<br />

Gonick at al.<br />

(1998)<br />

Dorman and<br />

Freeman<br />

(2002)<br />

Giridhar and<br />

Isom (1990)<br />

Table AX5-5.4. Studies <strong>of</strong> the Effects <strong>of</strong> <strong>Lead</strong> Exposure on Renin-angiotensin System, Kallikrein-Kinin System,<br />

Prostaglandins, Endothelin, and Atrial Natriuretic Peptide (ANP)<br />

Species/<br />

Tissue<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Male SD rats Weaning 16 Pb acetate<br />

60 ppm<br />

drinking water<br />

Male SD rats 200 g 32 Pb acetate<br />

100 ppm<br />

drinking water<br />

Male SD rats 2 mo 21 Pb acetate<br />

100 ppm<br />

drinking water<br />

VSMC<br />

(rat aorta)<br />

— — 0.0, 0.02, 0.2,<br />

2.0 mg/dL<br />

Male SD rats 150–175 g 20 Pb acetate 0.01,<br />

0.01, 0.5, 1.0<br />

mg/Kg, BiW, IP<br />

10 mo Blood 24.2 ±<br />

1.8 µg/dL<br />

BP, HR, carotid<br />

blood flow<br />

Plasma ACE,<br />

Kininase Kallikrein<br />

activities dp/dt<br />

2–8 wks — BP ACE activity in<br />

plasma, aorta, heart,<br />

kidney<br />

12 wks — BP Urinary Tx B2, 6keto<br />

PGF1<br />

up to 48 hrs 0.0 to 2<br />

mg/dL<br />

— Arachidonic acid<br />

(AA), DNA<br />

synthesis, cell<br />

proliferation + cell<br />

viability<br />

— Pb exposure raised BP<br />

and dp/dt, lowered carotid<br />

blood flow without<br />

changing HR. This was<br />

associated with marked<br />

increase in plasma ACE,<br />

Kininase <strong>II</strong> and Kininase I<br />

activities.<br />

— Pb exposure raised BP,<br />

ACE activity in plasma<br />

and tested tissues<br />

markedly increased<br />

peaking within 2–4 wks<br />

followed by a decline to<br />

subnormal values.<br />

— Pb exposure raised BP but<br />

did not affect urinary PG<br />

metabolite excretion<br />

rates.<br />

Ang <strong>II</strong>, FCS Pb augmented Ang <strong>II</strong><br />

stimulated AA release in<br />

a concentrationdependent<br />

fashion. At<br />

low concentrations, Pb<br />

augmented Ang <strong>II</strong>stimulated<br />

DNA synthesis<br />

and lowered cell count in<br />

unstimulated cells.<br />

30 days — — ANF — Pb exposure resulted in<br />

fluid retention (↓urine<br />

flow + unchanged fluid<br />

intake + weight gain).<br />

This was associated with<br />

decreased plasma and<br />

hypothalamic ANF levels<br />

.


AX5-70<br />

Reference<br />

Shelkovnikov<br />

and Gonick<br />

(2001)<br />

Purdy et al.<br />

(1997)<br />

Oishi et al.<br />

(1996)<br />

Valencia et al.<br />

(2001)<br />

Species/<br />

Tissue<br />

Table AX5-5.5. Studies <strong>of</strong> Effect <strong>of</strong> <strong>Lead</strong> on Vascular Contractility<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

Rat aorta rings Pb acetate<br />

10 −8 to 10 −4<br />

Male SD rats 8 wks Pb acetate 100<br />

ppm in water<br />

Male Wistar<br />

rats<br />

Wistar rat<br />

thoracic aorta<br />

rings<br />

7 wks 6 sets/<br />

experiment<br />

Short<br />

incubations<br />

— Vasoconstriction/<br />

vasodilation<br />

3 mo — BP Aorta ring<br />

response to NE,<br />

phenylephrine,<br />

acetylcholine, and<br />

nitroprusside<br />

Pb acetate 1–3 mo Mesenteric art<br />

and aorta<br />

response to<br />

acetylcholine in<br />

presence or<br />

absence <strong>of</strong> NOS<br />

inhibitor (L-<br />

NAME)<br />

Pb acetate<br />

0.1–3.1 mM<br />

Rapid<br />

response<br />

in vitro<br />

— In vitro<br />

contractile<br />

response<br />

Pb acetated did not cause<br />

vasoconstriction and did<br />

not modify the response<br />

to NE, isoproterenol,<br />

phorbol ester or<br />

acetylcholine but raised<br />

contractile response to<br />

submaximal Ca 2+<br />

concentration<br />

Pb exposure raised BP.<br />

Aorta ring<br />

vasoconstrictive response<br />

to NE and phenylephrine<br />

and vasodilatory<br />

response to acetylcholine<br />

and nitroprusside were<br />

unchanged.<br />

Vasorelaxation response<br />

to acetylcholine in<br />

presence <strong>of</strong> L-NAME<br />

was significantly reduced<br />

in mesenteric art, but not<br />

aorta <strong>of</strong> Pb-exposed<br />

animals (Inhibition <strong>of</strong><br />

hyperpolarizing factor)<br />

Pb induced a<br />

concentration-dependent<br />

vasoconstriction in intact<br />

and endothelial-denuded<br />

rings in presence or<br />

absence <strong>of</strong> α-1 blocker,<br />

PKC inhibitor, L. type<br />

Ca 2+ channel blocker or<br />

intra- and extracellular<br />

Ca 2+ depletion.<br />

However, the response<br />

was abrogated by<br />

lanthanum (a general Ca<br />

channel blocker)


AX5-71<br />

Reference<br />

Kaji et al.<br />

(1995a)<br />

Kaji et al.<br />

(1995b)<br />

Fujiwara et al.<br />

(1998)<br />

Kishimoto<br />

et al. (1995)<br />

Ueda D. et al.<br />

(1997)<br />

Species/<br />

Tissue<br />

Bovine aorta<br />

endothelial<br />

cells<br />

Bovine aorta<br />

endothelial<br />

cells<br />

Humanumbilical<br />

vein<br />

endothelia<br />

cells<br />

Human<br />

umbilical vein<br />

endothelial<br />

cells<br />

Table AX5-5.6. Effects <strong>of</strong> <strong>Lead</strong> on Cultured Endothelial Cell Proliferation, Angiogenesis, and<br />

Production <strong>of</strong> Heparan Sulfate Proteoglycans and tPA<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

— 4 sets per<br />

experiment<br />

— 4–5 sets per<br />

experiment<br />

— 6 set per<br />

experiment<br />

— 3 sets per<br />

experiment<br />

— 3 sets per<br />

experiment<br />

Pb nitrate<br />

5–50 µM<br />

Pb nitrate<br />

0.5–5 µM<br />

Pb nitrate<br />

5 and 10 µM<br />

Pb acetate<br />

1–100 FM<br />

Pb acetate<br />

1–100 µM<br />

24 hrs — Endothelial<br />

damage<br />

24 hrs — 3H-thymidine<br />

incorporation, cell<br />

count,<br />

morphology,<br />

LDH release<br />

48 hrs — Appearance <strong>of</strong><br />

cells in denuded<br />

areas <strong>of</strong><br />

monolayer, DNA<br />

synth<br />

24 hrs — Formation <strong>of</strong><br />

tube-like<br />

structures (angiogenesis<br />

assay, on<br />

Matrigel (BM)<br />

24 hrs — Tube <strong>for</strong>mation<br />

on Matrigel<br />

matrix<br />

Co-incubation<br />

with cadmium<br />

Stimulation<br />

w/βFGF and<br />

αFGF<br />

Stimulation<br />

w/Zn<br />

Addition <strong>of</strong> Pb alone<br />

resulted in mild<br />

deendothelialization <strong>of</strong><br />

the monolayers and<br />

markedly increased<br />

cadmium-associated<br />

endothelial damage.<br />

Incubation w/Pb resulted<br />

in a concentrationdependent<br />

reduction <strong>of</strong><br />

DNA synthesis and cell<br />

count, caused some shape<br />

change (polygonal<br />

→spindle) and reduced<br />

βFGF- and αFGFmediated<br />

proliferation.<br />

Pb inhibited appearance<br />

<strong>of</strong> endothelial cells in the<br />

denuded section <strong>of</strong><br />

monolayer and attenuated<br />

the healing response to<br />

Zinc.<br />

— Pb inhibited tube<br />

<strong>for</strong>mation concentrationdependently<br />

and tube<br />

lengthening time<br />

dependently.<br />

PKC activator<br />

and inhibitor<br />

Pb inhibited tube<br />

<strong>for</strong>mation concentrationdependently<br />

and tube<br />

lengthening time<br />

dependently. These<br />

effects were independent<br />

<strong>of</strong> PKC.


AX5-72<br />

Reference<br />

Fujiwara and<br />

Kaji<br />

(1999)<br />

Kaji et al.<br />

(1991)<br />

Kaji et al.<br />

(1997)<br />

Table AX5-5.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cultured Endothelial Cell Proliferation, Angiogenesis, and<br />

Production <strong>of</strong> Heparan Sulfate Proteoglycans and tPA<br />

Species/<br />

Tissue<br />

Bovine aorta<br />

endothelial<br />

cells<br />

Bovine aorta<br />

endothelial<br />

cells<br />

Bovine aorta<br />

endothelial<br />

cells<br />

(confluent)<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

— 4 sets per<br />

experiment<br />

— 4–5 sets per<br />

experiment<br />

Pb nitrate<br />

0.5, 1, 2 µM<br />

Pb nitrate<br />

0, 1–20 µM<br />

— N/A Pb chloride<br />

10 M<br />

12–48 hrs βFGF production/<br />

distribution<br />

Heparan sulfate<br />

production (sulfate<br />

incorporation)<br />

DNA synthesis (cell<br />

proliferation)<br />

βFGF binding assay<br />

24–48 hrs Glycosaminoglycan<br />

(GAG) synthesis<br />

(sulfate incorporation)<br />

24 hrs N/A Synthesis <strong>of</strong> heparan<br />

sulfate proteoglycans<br />

(HSPGs) and their core<br />

proteins<br />

Heparin, AntiβFGF<br />

antibody<br />

Pb and anti-βFGF alone<br />

or together equally<br />

reduced DNA synthesis.<br />

PB did not change<br />

endogenous βFGF<br />

production but reduced<br />

its HSPG-bound<br />

component. This was<br />

due to diminished<br />

heparan sulfate synthesis<br />

as opposed to<br />

interference with βFGF<br />

binding property.<br />

At 10 FM, Pb<br />

significantly reduced<br />

production <strong>of</strong> total<br />

GAGs. Heparan sulfate<br />

was reduced more<br />

severely than other<br />

GAGs. Cell surface<br />

GAG was reduced more<br />

severely than found in<br />

the medium.<br />

In confluent cells, Pb<br />

suppressed incorporation<br />

<strong>of</strong> precursors into HSPG<br />

in the cell layer to a<br />

greater extent than<br />

chondroitin/dermatan<br />

sulfate proteoglycans. Pb<br />

suppressed lowmolecular<br />

weight HSPGs<br />

more than the highmolecular<br />

weight<br />

subclass. The core<br />

proteins were slightly<br />

increased by Pb<br />

exposure.


AX5-73<br />

Reference<br />

Fujiwara and<br />

Kaji<br />

(1999)<br />

Kaji et al.<br />

(1992)<br />

Table AX5-5.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cultured Endothelial Cell Proliferation, Angiogenesis, and<br />

Production <strong>of</strong> Heparan Sulfate Proteoglycans and tPA<br />

Species/<br />

Tissue<br />

Bovine aorta<br />

endothelial<br />

cells (growing<br />

10% BCS)<br />

Human<br />

umbilical vein<br />

endothelial<br />

cells<br />

(confluent)<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Interventions Results<br />

— 4 sets per<br />

experiment<br />

— 5 sets per<br />

experiment<br />

Pb nitrate<br />

0.1 µM<br />

48 hrs Sulfate and<br />

glucosamine<br />

incorporation in GAGs,<br />

quantification <strong>of</strong> high<br />

and low MW-HSPG,<br />

identification <strong>of</strong><br />

perlecan core protein<br />

0.01–1 µM t-PA release, DNA<br />

synth, protein synth<br />

(leucine incorporation)<br />

Thrombin and<br />

ET-1<br />

stimulations<br />

In growing cells, Pb<br />

depressed high-MW<br />

HSPGs production but<br />

had little effect on low-<br />

MW HSPGx (~50 KD).<br />

The core protein <strong>of</strong><br />

perlecan (400 KD) was<br />

significantly reduced by<br />

Pb exposure.<br />

Pb exposure reduced<br />

basal and thrombinstimulation<br />

t-PA release<br />

and worsened ET-1<br />

induced inhibition <strong>of</strong> t-<br />

PA release.


AX5-74<br />

Reference<br />

Fugiwara<br />

et al. (1995)<br />

Carsia et al.<br />

(1995)<br />

Yamamoto<br />

et al. (1997)<br />

Species/<br />

Tissue<br />

Bovine aorta<br />

vascular<br />

smooth<br />

muscle cell<br />

Rat aorta<br />

VSMC cells<br />

(80–90%<br />

confluent)<br />

Human aorta<br />

VSMC and<br />

fetal lung<br />

fibroblasts<br />

(confluent)<br />

Table AX5-5.7. Studies <strong>of</strong> the Effect <strong>of</strong> <strong>Lead</strong> on Cultured Vascular Smooth Muscle Cells<br />

Pb Exposure Measured Parameters<br />

Age/<br />

Weight n Dosage Duration Pb Level CVS Other Reference Species/Tissue<br />

4 sets per<br />

experiment<br />

$3 sets per<br />

experiment<br />

5 sets per<br />

experiment<br />

Pb nitrate<br />

0.5–10 µM<br />

Pb citrate 100<br />

and 500 µg/L<br />

Pb chloride<br />

0.5–10 µM<br />

24 hrs — DNA synthesis Coincubation<br />

w/βFGF,<br />

αFGF. pDGF<br />

Time to<br />

confluence<br />

(~90% <strong>for</strong><br />

control<br />

experiments)<br />

Cell density (cell<br />

#/Cm 2 ), cell<br />

morphology,<br />

membrane lipid<br />

analysis, receptor<br />

densities (Ang-<strong>II</strong>,<br />

α, β, ANP<br />

24 hrs t-PA and PAI-1<br />

release<br />

Pb caused a<br />

concentration-dependent<br />

increase in DNA<br />

synthesis. Co-incubation<br />

w/βFGF and Pb resulted<br />

in an additive stimulation<br />

<strong>of</strong> VSMC DNA synth.<br />

However, Pb inhibited<br />

PDGF and αFGFinduced<br />

DNA synthesis.<br />

At low concentration, Pb<br />

caused VSMC<br />

hyperplasia, phenotypic<br />

trans<strong>for</strong>mation from<br />

spindle-to-cobblestone<br />

(neointima-like) shape,<br />

reduced Ang <strong>II</strong> receptor<br />

density without changing<br />

α, β, ANP receptors,<br />

increased arachidonic<br />

acid content <strong>of</strong> cell<br />

membrane.<br />

At 2 µM or higher<br />

concentrations, Pb<br />

resulted in a<br />

concentration-dependent<br />

decline in t-PA release in<br />

both cell types. Pb<br />

increased PAI-1 release<br />

in fibroblasts but lowered<br />

PAI-1 in VSMC.


ANNEX TABLES AX5-6<br />

AX5-75


AX5-76<br />

Table AX5-6.1. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Laboratory Animal Studies<br />

Compound Dose and Duration Cell Type Co-exposure Effects Reference<br />

Pb acetate 0.5, 5, or 25 ppm given in drinking<br />

water–duration not given.<br />

Number <strong>of</strong> animals per group was<br />

not given.<br />

Pb acetate 0–4000 ppm given in drinking<br />

water <strong>for</strong> 104 wks.<br />

Pb acetate 50, 250, or 1000 ppm given in<br />

drinking water <strong>for</strong> 15 wks.<br />

Number <strong>of</strong> mice per group in initial<br />

exposures not given.<br />

Number <strong>of</strong> mice at analysis ranged<br />

from 19–25.<br />

Female C3HSt mice<br />

infected with MMTV<br />

(Murine mammary<br />

tumor virus)–age not<br />

given<br />

Wild type (WT) and<br />

metallothionine null (MT<br />

null) mice<br />

Female albino Swiss<br />

Mice–3 wks old<br />

Selenium, 0.15–<br />

1 ppm (duration not<br />

given) in diet ( Se<br />

prevents spontaneous<br />

tumors in these mice)<br />

Pb acetate exposed mice exhibited greater mortality unrelated to<br />

the tumor <strong>for</strong>mation.<br />

25 ppm suppressed tumor <strong>for</strong>mation, but increased the<br />

aggressiveness <strong>of</strong> the tumors.<br />

5 ppm increased tumor <strong>for</strong>mation, but had no effect on growth<br />

rates.<br />

0.5 ppm with low selenium exhibited 80% tumor <strong>for</strong>mation and<br />

reduced weight gains that recovered.<br />

0.5 ppm with high selenium exhibited normal weight gain, but<br />

tumor incidence still reached 80%.<br />

Control data described as “significantly lower” but not given.<br />

Methods poorly described and data not shown.<br />

None Renal proliferative lesions were much more common and severe<br />

in MT null mice than WT mice. MT null mice could not <strong>for</strong>m<br />

renal inclusion bodies even with prolonged Pb exposure and this<br />

could have contributed to increase in the carcinogenic potential<br />

<strong>of</strong> Pb.<br />

Urethane 1.5 mg/g<br />

given i.p.<br />

No signs <strong>of</strong> Pb poisoning. No Pb effects on growth or weight<br />

gain.<br />

Urethane added to induce lung tumors.<br />

Pb did not affect urethane metabolism.<br />

Pb did not affect number <strong>of</strong> tumors or affect tumor size.<br />

Pb alone was not evaluated.<br />

Pb levels did increase in tissues.<br />

Schrauzer (1987)<br />

Waalkes et al.<br />

(2004)<br />

Blakley<br />

(1987)


AX5-77<br />

Table AX5-6.1 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Laboratory Animal Studies<br />

Compound Dose and Duration Cell Type Co-exposure Effects Reference<br />

Pb acetate 50 or 1000 ppm 50 or 1000 ppm<br />

given in drinking water <strong>for</strong><br />

280 days.<br />

Number <strong>of</strong> mice pre group in initial<br />

exposures not given.<br />

Number <strong>of</strong> mice at end were 50 per<br />

dose.<br />

Pb acetate 60 mg/kg injected s.c. weekly <strong>for</strong><br />

5 wks followed by observation <strong>for</strong><br />

80 wks. 13 treated and 14 control<br />

rats.<br />

Pb acetate 1 or 100 µg/L given in the drinking<br />

water <strong>for</strong> 31 wks<br />

8 animals per group<br />

Female albino Swiss<br />

Mice–8 wks old<br />

Fisher F344/NSle rats–<br />

3 wks old<br />

Male Wistar Rats—<br />

weanlings<br />

None Mice have high rate <strong>of</strong> spontaneous leukemia from endemic viral<br />

infection.<br />

No signs <strong>of</strong> Pb poisoning. No Pb effects on growth or weight<br />

gain.<br />

Pb did increase leukemia-related mortality possibly due to<br />

immunosuppression.<br />

Pb levels did increase in tissues.<br />

Data indicate that Pb may be immunosuppressive, though the<br />

exact mechanism is not understood.<br />

None Pb induced tumors at the site <strong>of</strong> injection in 42% <strong>of</strong> rats<br />

though data was not shown.<br />

Control data not indicated or shown.<br />

Pb accumulated in tumor tissue, tooth, and bone. This data<br />

was shown.<br />

0.2–4 % calcium<br />

carbonate given in the<br />

diet <strong>for</strong> 31 wks.<br />

No differences in drinking water or food consumption.<br />

High Pb and high calcium reduced growth.<br />

No deaths in low calcium groups.<br />

10/24 rats from high calcium diet died (4 from controls and 3<br />

each from Pb groups). All 10 had kidney or bladder stones.<br />

0/8 rats in low calcium no Pb had kidney pathology<br />

2/8 rats in low calcium low Pb had nephrocalcinosis.<br />

7/8 rats in low calcium high Pb had nephrocalcinosis.<br />

3/4 rats in high calcium no Pb had nephrocalcinosis.<br />

1/5 rats in high calcium low Pb had a renal pelvic carcinoma.<br />

3/5 rats had nephrocalcinosis.<br />

3/5 rats in high calcium high Pb had transitional cell<br />

hyperplasia. 2/5 rats had invasive renal pelvic carcinoma.<br />

Pb tissue levels were same regardless <strong>of</strong> dietary calcium<br />

levels.<br />

Blakley<br />

(1987)<br />

Teraki and<br />

Uchiumi (1990)<br />

Bogden et al.<br />

(1991)


AX5-78<br />

Table AX5-6.2. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Human Cell Cultures<br />

Compound Dose and Duration Cell Type Co-exposure Effects Reference<br />

Pb chromate Anchorage Independence<br />

(0.1–1 µM <strong>for</strong> 48 h)<br />

Pb chromate Anchorage Independence<br />

(0.1–1 µM <strong>for</strong> 48 h)<br />

Pb chromate Morphological Trans<strong>for</strong>mation<br />

(2 µg/mL <strong>for</strong> 24 h, per<strong>for</strong>med<br />

3 times immediately after<br />

passage)<br />

Anchorage Independence (0.2–<br />

2 µg/mL or cells isolated during<br />

morphological trans<strong>for</strong>mation)<br />

Neoplastic Trans<strong>for</strong>mation (cells<br />

isolated during morphological<br />

trans<strong>for</strong>mation)<br />

Pb acetate Anchorage Independence<br />

(500–2000 µM <strong>for</strong> 24 h)<br />

Human Foreskin<br />

Fibroblasts<br />

In H-MEM +15% FCS<br />

Human Foreskin<br />

Fibroblasts<br />

In H-MEM +15% FCS<br />

HOS TE 85 in DMEM<br />

+ 10% FBS<br />

Human Foreskin<br />

Fibroblasts (Chinese)<br />

In DMEM +10% FCS<br />

None Pb chromate-induced concentration-dependent increase in<br />

anchorage independence.<br />

None Pb chromate-induced concentration-dependent increase in<br />

anchorage independence.<br />

None Pb chromate induced foci <strong>of</strong> morphological trans<strong>for</strong>mation<br />

after repeated exposure and passaging.<br />

Pb chromate did not induce anchorage independence, but<br />

cells from the foci obtained during morphological<br />

trans<strong>for</strong>mation.<br />

Pb chromate did not induce neoplastic trans<strong>for</strong>mation in the<br />

cells from the foci obtained during morphological<br />

trans<strong>for</strong>mation.<br />

Studied as a chromate compound. Role <strong>of</strong> Pb not mentioned<br />

or considered.<br />

3-aminotriazole (3-AT)<br />

(80 mM to inhibit<br />

catalase)<br />

Pb acetate-induced concentration-dependent increase in<br />

anchorage independence. Anchorage independence not<br />

affected by 3-AT.<br />

Biedermann and<br />

Landolph (1987)<br />

Biedermann and<br />

Landolph (1990)<br />

Sidhu et al. (1991)<br />

Hwua and Yang<br />

(1998)


AX5-79<br />

Table AX5-6.3. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Carcinogenesis Animal Cell Cultures<br />

Compound Dose and Duration Cell Type Co-exposure Effects Reference<br />

Pb acetate Morphological Trans<strong>for</strong>mation<br />

(10–50 µM <strong>for</strong> 48 h)<br />

Pb chloride Morphological Trans<strong>for</strong>mation<br />

(doses not given)<br />

Pb chromate Enhancement <strong>of</strong> Simian<br />

Adenovirus (SA7) induced<br />

morphological trans<strong>for</strong>mation.<br />

(80–1,240 µM <strong>for</strong> 20 h)<br />

Pb chromate Morphological Trans<strong>for</strong>mation<br />

(10–50 µM <strong>for</strong> 24 h)<br />

Pb chromate<br />

(and pigments<br />

containing Pb<br />

chromate)<br />

Anchorage Independence <strong>for</strong> cells<br />

isolated during morphological<br />

trans<strong>for</strong>mation<br />

Neoplastic Trans<strong>for</strong>mation <strong>for</strong> cells<br />

isolated during morphological<br />

trans<strong>for</strong>mation.<br />

Morphological Trans<strong>for</strong>mation<br />

(0.04–8 µg/mL as Cr <strong>for</strong> 7 days)<br />

Anchorage Independence <strong>for</strong> cells<br />

isolated during morphological<br />

trans<strong>for</strong>mation<br />

Neoplastic Trans<strong>for</strong>mation <strong>for</strong> cells<br />

isolated during morphological<br />

trans<strong>for</strong>mation<br />

Pb chromate Morphological Trans<strong>for</strong>mation<br />

(0.02–0.88 µg/mL as Cr <strong>for</strong> 7 days)<br />

Primary SHE cells in<br />

AMEM + 10% FBS<br />

C3H10T1/2 cells in<br />

EMEM +10% FBS<br />

Primary SHE cells in<br />

DMEM + 10% FBS<br />

C3H10T1/2 cells in<br />

EMEM + 10% FBS<br />

Primary SHE cells in<br />

DMEM + 10% FCS<br />

Primary SHE cells in<br />

DMEM + 10% FCS<br />

None Pb acetate was weakly positive inducing a 0.19–1.6%<br />

increase in trans<strong>for</strong>mation. There was a weak dose<br />

response. There were no statistical analyses <strong>of</strong> these data.<br />

Zelik<strong>of</strong>f et al. (1988)<br />

None Pb chloride did not induce morphological trans<strong>for</strong>mation. Patierno et al. (1988),<br />

Patierno and<br />

Landolph (1989)<br />

(both papers present<br />

the same data)<br />

None Pb chromate enhanced SA7-induced morphological<br />

trans<strong>for</strong>mation.<br />

Studied as a chromate compound. Role <strong>of</strong> Pb not<br />

mentioned or considered.<br />

None Pb chromate induced morphological and neoplastic<br />

trans<strong>for</strong>mation.<br />

Cells exhibiting morphological trans<strong>for</strong>mation grew in s<strong>of</strong>t<br />

agar and grew in nude mice.<br />

Studied as a chromate compound.<br />

None Pb chromate induced morphological and neoplastic<br />

trans<strong>for</strong>mation.<br />

Cells exhibiting morphological trans<strong>for</strong>mation grew in s<strong>of</strong>t<br />

agar and grew in nude mice.<br />

Studied as a chromate compound.<br />

None Pb chromate induced morphological trans<strong>for</strong>mation more<br />

potently (9-fold) than other chromate compounds.<br />

Schechtman et al.<br />

(1986)<br />

Patierno et al. (1988)<br />

Patierno and<br />

Landolph (1989)<br />

(both papers present<br />

the same data)<br />

Elias et al. (1989)<br />

Elias et al. (1991)


AX5-80<br />

Table AX5-6.3 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Carcinogenesis Animal Cell Cultures<br />

Compound Dose and Duration Cell Type Co-exposure Effects Reference<br />

Pb nitrate Morphological Trans<strong>for</strong>mation<br />

(0.04–8 µg/mL as Cr <strong>for</strong> 7 days)<br />

Abbreviations<br />

Primary SHE cells in<br />

DMEM + 10% FCS<br />

Cells<br />

SHE—Syrian hamster embryo;<br />

C3H10T/12 cells are a mouse embryo cell line<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

DMEM—Dulbecco’s Minimal Essential Medium;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

H-MEM—Minimum essential medium/nutrient mixture–F12-Ham<br />

HOS TE—Human osteosarcoma cell line TE<br />

Differences between the serum are unclear as insufficient details are provided by authors to distinguish.<br />

Calcium chromate Pb nitrate alone did not induce significant levels <strong>of</strong><br />

trans<strong>for</strong>mation.<br />

Pb nitrate plus calcium chromate increased the potency <strong>of</strong><br />

calcium chromate to that <strong>of</strong> Pb chromate. Data suggest Pb<br />

ions are synergistic with chromate ions in inducing<br />

neoplastic trans<strong>for</strong>mation.<br />

Elias et al. (1991)


AX5-81<br />

Table AX5-6.4. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Laboratory Animal Studies.<br />

Compound Dose and Duration Species Co-exposure Effects Reference<br />

Pb acetate 2.5 mg/100 g given i.p.<br />

as daily injection <strong>for</strong> 5–<br />

15 days<br />

or<br />

10–20 mg/100 g given i.p.<br />

as single injection and<br />

animals studied after<br />

15 days<br />

5 animals per group.<br />

Chromosome damage in<br />

bone marrow<br />

Pb acetate 25–400 mg/kg given i.p.<br />

as single injection and<br />

animals studied after 24 h<br />

For some chromosome<br />

damage studies animals<br />

were treated with 25–<br />

200 mg/kg given i.p. as<br />

a series <strong>of</strong> 3, 5, or 7 daily<br />

injections and animals<br />

studied after 24 h after the<br />

last injection.<br />

5 animals per group.<br />

Chromosome damage,<br />

sister chromatid exchange,<br />

in bone marrow and<br />

spermatocytes.<br />

Pb acetate 200 or 400 mg/kg given by<br />

gavage daily <strong>for</strong> 5 days<br />

5 animals per group<br />

Chromosome aberrations in<br />

bone marrow and<br />

spermatocytes.<br />

Female Norway Rat Selenium (0.012–<br />

0.047 mg/100g or<br />

0.094–0.188 mg/100 g<br />

given i.p. with Pb)<br />

Male Swiss Mice,<br />

9–12 wks old<br />

Male Swiss Mice,<br />

9–12 wks old<br />

Pb induced chromosome damage after chronic treatment. It<br />

was not dose dependent as only 1 dose was studied. The<br />

effects <strong>of</strong> selenium on Pb effects are unclear as selenium<br />

alone induced substantial chromosome damage.<br />

The single dose exposure also induced chromosome damage,<br />

but untreated controls were not done in this regimen. There<br />

is some mention that this dose regimen is toxic to the animals<br />

as selenium modulated the lethal effects, but no explanation<br />

<strong>of</strong> how many animals died.<br />

None Pb induced chromosome damage in a dose dependent manner<br />

at 100–400 mg/kg after a single dose or repeated does<br />

exposure in bone marrow cells.<br />

In spermatocytes, Pb also induced chromosome damage in a<br />

dose dependent manner at 50–400 mg/kg after a single dose<br />

or repeated dose exposure in bone marrow cells.<br />

Pb induced SCE at 50 and 100 mg/kg. A lower dose was<br />

negative and higher doses were not done.<br />

Calcium chloride (40 or<br />

80 mg/kg by gavage<br />

daily <strong>for</strong> 3 days given<br />

2 wks after Pb<br />

exposure)<br />

Pb induced chromosome damage at both 200 and 400 mg/kg<br />

in bone marrow cells and spermatocytes. Calcium appeared<br />

to block this effect.<br />

Chakraborty<br />

et al. (1987)<br />

Fahmy (1999)<br />

Aboul-Ela (2002)


AX5-82<br />

Table AX5-6.4 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Laboratory Animal Studies.<br />

Compound Dose and Duration Species Co-exposure Effects Reference<br />

Pb nitrate 100–200 mg/kg given i.v.<br />

on 9th day <strong>of</strong> gestation<br />

onwards <strong>for</strong> 9 days.<br />

Mothers and fetuses<br />

analyzed on G18.<br />

Group size not given.<br />

Resorptions, fetal viability<br />

and chromosome damage,<br />

SCE and NOR in the<br />

mother and fetus were<br />

examined. Mother–bone<br />

marrow; fetus liver or lung<br />

3 mothers and fetuses per<br />

dose were analyzed.<br />

Pb nitrate 10, 20, or 40 mg/kg given<br />

i.p. 24 h<br />

6 animals per group.<br />

Chromosome damage and<br />

Mitotic Index in bone<br />

marrow<br />

Pb nitrate 5, 10, or 20 mg/kg given<br />

i.p. 24 h<br />

6 animals per group.<br />

Chromosome damage in<br />

bone marrow.<br />

50 metaphases per animal<br />

<strong>for</strong> a total <strong>of</strong> 300 (X6).<br />

ICR Swiss Webster Mice,<br />

6–8 wk old<br />

Swiss Albino Mice,<br />

8 wks old<br />

Swiss Albino Mice,<br />

8 wks old<br />

None Pb levels were found in both mother and fetus indicating no<br />

problems crossing the placenta.<br />

All doses indicated increased resorption and decreased<br />

placental weights. No effects on fetal weight.<br />

Significant increase in SCE in mothers at 150 and 200 mg/kg.<br />

No increase in SCE in fetuses.<br />

Significant decrease in NOR in both mother and fetuses.<br />

No gaps or breaks in mothers or fetuses.<br />

Some weak aneuploidy at lowest dose.<br />

Some karyotypic chromosome damage was seen.<br />

No explanation <strong>of</strong> how many cells analyzed per animal<br />

(3 animals per dose were analyzed) as only 20– 40 cells were<br />

analyzed.<br />

There was no dose response and no statistical analyses <strong>for</strong><br />

chromosome damage. No details on how many animals<br />

analyzed <strong>for</strong> metaphase damage or how many cells per<br />

animal.<br />

Data interpretation is also complicated as too few metaphases<br />

were analyzed 10–25 <strong>for</strong> SCE. Not given <strong>for</strong> CA.<br />

No detail on potential maternal toxicity.<br />

Phyllanthus fruit extract<br />

(685 mg/kg) or ascorbic<br />

acid (16.66 mg/kg)<br />

given by gavage <strong>for</strong><br />

7 days<br />

Ferric chloride<br />

(18 mg/kg) given i.p.<br />

<strong>for</strong> 24 h administered<br />

1 h be<strong>for</strong>e, 1 h after, or<br />

together with Pb nitrate<br />

Pb nitrate increased the amount <strong>of</strong> chromosome damage at<br />

each dose. But there was no dose response and a similar<br />

level <strong>of</strong> damage was seen <strong>for</strong> each dose.<br />

Phyllanthus fruit extract reduced the amount <strong>of</strong> damage at<br />

each dose. Ascorbic acid reduced the damage at the lowest<br />

dose but increased it at the higher doses.<br />

Higher concentrations <strong>of</strong> Pb nitrate reduced the mitotic index.<br />

This effect was reversed by ascorbate and Phyllanthus only at<br />

the moderate dose.<br />

Pb nitrate increased the amount <strong>of</strong> chromosome damage in a<br />

dose-dependent manner.<br />

Iron exhibited some modifications <strong>of</strong> Pb induced damage:<br />

If administered 1 h be<strong>for</strong>e Pb plus simultaneously it reduced<br />

the damage. If administered with Pb only at same time it<br />

reduced damage in the lower doses. If Pb was started 1 h<br />

be<strong>for</strong>e iron there was no effect.<br />

Thus iron may antagonize Pb perhaps by blocking uptake.<br />

Nayak et al. (1989b)<br />

Dhir et al. (1990)<br />

Dhir et al. (1992a)


AX5-83<br />

Table AX5-6.4 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Laboratory Animal Studies.<br />

Compound Dose and Duration Species Co-exposure Effects Reference<br />

Pb nitrate 5 or 10 mg/kg given by<br />

gavage <strong>for</strong> 24 h<br />

6 animals per group.<br />

Chromosome aberrations in<br />

bone marrow<br />

Pb nitrate 10, or 20 mg/kg given i.p.<br />

48 h<br />

12 animals per group.<br />

Micronucleus <strong>for</strong>mation in<br />

bone marrow<br />

Pb nitrate 10, 20, or 40 mg/kg given<br />

i.p. 24 h<br />

5 animals per group.<br />

SCE in bone marrow<br />

Pb nitrate 0.625–80 mg/kg given i.p.<br />

<strong>for</strong> 12, 24 or 36 h<br />

12 animals per group<br />

Micronucleus <strong>for</strong>mation in<br />

bone marrow. 4000<br />

erythorocytes scored per<br />

animal<br />

Pb nitrate 0.7–89.6 mg/kg given by<br />

gavage <strong>for</strong> 24, 48, or 72 h,<br />

or 1 or 2 wks<br />

5 animals per group.<br />

Cell viability by trypan blue<br />

Single strand breaks in<br />

white blood cells<br />

Swiss Albino Mice,<br />

7–8 wks old<br />

Swiss Albino Mice,<br />

6 wks old<br />

Swiss Albino Mice,<br />

6–8 wks old<br />

Swiss Albino Mice,<br />

6–8 wks old<br />

Swiss Albino Mice,<br />

4 wks old<br />

Zirconium oxychloride<br />

(110 or 220 mg/kg)<br />

given by gavage <strong>for</strong><br />

24 h administered 2 h<br />

be<strong>for</strong>e, 2 h after or<br />

together with Pb nitrate<br />

Phyllanthus fruit extract<br />

(685 mg/kg) or ascorbic<br />

acid (16.66 mg/kg)<br />

given by gavage <strong>for</strong><br />

7 days<br />

Phyllanthus fruit extract<br />

(685 mg/kg) or ascorbic<br />

acid (16.66 mg/kg)<br />

given by gavage <strong>for</strong><br />

7 days<br />

Pb nitrate increased the amount <strong>of</strong> chromosome damage in a<br />

dose-associated manner.<br />

Zirconium induced a dose-associated increase in<br />

chromosome damage.<br />

Zirconium exhibited minimal modification <strong>of</strong> Pb nitrateinduced<br />

damage when administered 2 h be<strong>for</strong>e or after Pb<br />

nitrate.<br />

Administering the two together increased the damage.<br />

Pb nitrate increased the amount <strong>of</strong> micronuclei at both doses<br />

in a dose-associated manner. The 48 h recovery time was<br />

lower than 24 h but still elevated.<br />

Phyllanthus fruit extract reduced the amount <strong>of</strong> damage at<br />

both doses. Ascorbic acid reduced the damage at the lowest<br />

dose but increased it at the higher dose.<br />

Pb nitrate increased the amount <strong>of</strong> SCE in a dose-dependent<br />

manner. Pb nitrate had no effect <strong>of</strong> the proliferative rate<br />

index (consideration <strong>of</strong> metaphases in different division<br />

numbers)<br />

Phyllanthus fruit extract and ascorbic acid reduced the<br />

amount <strong>of</strong> damage at each dose.<br />

None Pb nitrate induced micronuclei but they did not increase with<br />

dose.<br />

Pb induced more micronuclei in males than in females.<br />

The ratio <strong>of</strong> polychromatic to normochromatic erythrocytes<br />

was elevated in Pb nitrate treated cells, but again did not<br />

increase with dose.<br />

None Viability was high (92–96%) at all doses.<br />

Pb nitrate induced single strand breaks but they did not<br />

increase with dose. In fact the 3 highest doses were all<br />

similar in magnitude and less than the 5 lowest doses.<br />

The 5 lowest doses were also similar in magnitude.<br />

Dhir et al. (1992b)<br />

Roy et al. (1992)<br />

Dhir et al. (1993)<br />

Jagetia and Aruna<br />

(1998)<br />

Devi et al. (2000)


AX5-84<br />

Table AX5-6.4 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Laboratory Animal Studies.<br />

Compound Dose and Duration Species Co-exposure Effects Reference<br />

Pb acetate 10 mg/kg given by gavage<br />

5 times a week <strong>for</strong> 4 wks.<br />

10 animals per group<br />

Chromosome Aberrations<br />

with 20 metaphases scored<br />

per animal<br />

Male Wistar rats,<br />

30 days old<br />

Cypermethrin No effects on weight gain.<br />

Pb acetate induced an increase in aneuploidy, and the percent<br />

<strong>of</strong> cells with damage, but did not increase structural damage<br />

or alterations in organ weight.<br />

Cypermethrin and Pb together increased structural<br />

aberrations that were predominately acentric fragments.<br />

However, this was compared to untreated controls and not the<br />

individual treatments. Considering the individual treatments,<br />

the two together are less than additive.<br />

Nehez et al. (2000)


AX5-85<br />

Table AX5-6.5. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell Cultures Mutagenesis<br />

Compound Dose and Duration Cell Type Co-exposure Effects Reference<br />

Pb acetate,<br />

In vitro<br />

Cytotoxicity–tritium<br />

incorporation (0.1–<br />

100 µM/mL <strong>for</strong> 2–24 h)<br />

Mutagenesis–HPRT<br />

modified to labeling <strong>of</strong><br />

6-thioguanine resistant cells<br />

(0.1–100 µM/mL <strong>for</strong><br />

2–24 h)<br />

Pb acetate Cytotoxicity (500–<br />

2,000 µM <strong>for</strong> 24 h)<br />

Mutagenicity–HPRT assay<br />

(500–2,000 µM <strong>for</strong> 24 h)<br />

Pb chromate Mutagenicity as 6thioguanine<br />

resistance<br />

(0.25–1 µM <strong>for</strong> 24 h)<br />

Human Keratinocytes<br />

pooled in MEM and low<br />

calcium MEM + 2% FBS<br />

Human Foreskin<br />

Fibroblasts (Chinese)<br />

in DMEM +10% FCS<br />

Human Foreskin<br />

Fibroblasts<br />

In EMEM +15% FCS<br />

None Decrease in tritium incorporation at 10–100 µM/mL.<br />

6 µM/L was selected as the concentration to study as tritiumincorporation<br />

was highest and greater than control.<br />

Tritium incorporation in the presence <strong>of</strong> 6-thioguanine (TG)<br />

was optimal after 4 h Pb acetate exposure and 5 days <strong>of</strong><br />

expression time. It was concluded that the significant<br />

increase relative to control indicated mutations. The<br />

argument made was that because these cells are TG resistant<br />

they must be mutated. However, this argument was not<br />

proven by sequencing or colony <strong>for</strong>mation in TG.<br />

3-aminotriazole (3-AT)<br />

(80 mM to inhibit<br />

catalase)<br />

Abbreviations<br />

Medium and Components<br />

MEM—Minimal Essential Medium;<br />

DMEM—Dulbecco’s Minimal Essential Medium;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

LC50 = 500 µM. Cytotoxicity not affected by 3-AT.<br />

Pb acetate was not mutagenic.<br />

Mutagenicity not affected by 3-AT.<br />

Ye (1993)<br />

Hwua and Yang<br />

(1998)<br />

None Pb chromate was not mutagenic. Biedermann and<br />

Landolph (1990)


AX5-86<br />

Compound<br />

Table AX5-6.6. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell Cultures Clastogenicity<br />

Assay (Concentration<br />

and Exposure Time)<br />

Pb chromate Chromosome aberrations<br />

(0.08–2 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome aberrations<br />

(0.1–5 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome aberrations<br />

(0.1–5 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome aberrations<br />

(0.1–5 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome aberrations<br />

(0.05–5 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome aberrations<br />

(0.05–5 µg/cm 2 <strong>for</strong> 24 h)<br />

Cell Type and Culture<br />

Medium Co-exposure Effects Reference<br />

Human Foreskin Fibroblasts<br />

(Caucasian) in EMEM + 15% FBS<br />

Primary Human Lung Cells in<br />

DMEM/F12 + 15% FBS<br />

Primary Human Lung Cells and<br />

WTHBF-6—human lung cells with<br />

hTERT in DMEM/F12 + 15% FBS<br />

WTHBF-6—human lung cells with<br />

hTERT in DMEM/F12 + 15% CCS<br />

WTHBF-6—human lung cells with<br />

hTERT in DMEM/F12 + 15% CCS<br />

WTHBF-6—human lung cells with<br />

hTERT in DMEM/F12 + 15% CCS<br />

Vitamin C<br />

(2 mM<br />

co-exposure<br />

<strong>for</strong> 24 h)<br />

None Pb chromate induced chromosome damage in a<br />

concentration dependent manner.<br />

This study was focused on chromate.<br />

None Pb chromate induced chromosome damage in a<br />

concentration dependent manner.<br />

This study was focused on chromate.<br />

None Pb chromate induced chromosome damage in a<br />

concentration dependent manner. Effects were similar in<br />

both cell types establishing the WTHBF-6 cells as a useful<br />

model.<br />

This study was focused on chromate.<br />

Vitamin C<br />

(2 mM<br />

co-exposure<br />

<strong>for</strong> 24 h)<br />

Pb chromate induced chromosome damage in a<br />

concentration dependent manner.<br />

Vitamin C blocked Cr ion uptake and the chromosome<br />

damage after Pb chromate exposure.<br />

This study was focused on chromate.<br />

Pb chromate induced chromosome damage in a<br />

concentration dependent manner.<br />

This study was focused on showing chromate and not Pb<br />

ions were the clastogenic species.<br />

None Pb chromate induced chromosome damage in a<br />

concentration dependent manner.<br />

This study was focused on comparing particulate chromate<br />

compounds.<br />

Wise et al.<br />

(1992)<br />

Wise et al.<br />

(2002)<br />

Wise et al.,<br />

(2004a)<br />

Xie et al. (2004)<br />

Wise et al.<br />

(2004b)<br />

Wise et al.<br />

(2005)


AX5-87<br />

Table AX5-6.6 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell Cultures Clastogenicity<br />

Compound<br />

Assay (Concentration<br />

and Exposure Time)<br />

Pb glutamate Pb ion uptake–ICPMS<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Chromosome Aberrations<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Pb glutamate Pb ion uptake–ICPMS<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Radioactive Pb<br />

ions<br />

No further<br />

specification<br />

Mitotic Index<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Growth Curve<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Cell cycle Analysis<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

LET = 13,600keV/µM<br />

Fluence <strong>of</strong><br />

2 H 10 6 particles/ cm 2<br />

Chromosome Aberrations<br />

Abbreviations<br />

hTERT is the catalytic subunit <strong>of</strong> human telomerase<br />

Medium and Components<br />

EMEM—Eagle’s Minimal Essential Medium<br />

DMEM/F12—Dulbecco’s Minimal Essential Medium/Ham’s F12<br />

CCS—Cosmic Calf Serum<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Cell Type and Culture<br />

Medium Co-exposure Effects Reference<br />

WTHBF-6—human lung cells with<br />

hTERT in DMEM/F12 + 15% CCS<br />

WTHBF-6—human lung cells with<br />

hTERT in DMEM/F12 + 15% CCS<br />

Human Foreskin Fibroblasts in<br />

DF-12 + 10% FCS<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

None Pb glutamate induced a concentration-dependent increase in<br />

intracellular Pb ions.<br />

Pb glutamate did not induce chromosome damage.<br />

None Pb glutamate induced a concentration-dependent increase in<br />

intracellular Pb ions.<br />

Pb glutamate increased the mitotic index, but inhibited<br />

growth and did not induce chromosome damage.<br />

None Pb induced chromosome damage that recurred<br />

with time and cell passaging. Analysis limited to<br />

~25 metaphases.<br />

Focused on radioactive effects <strong>of</strong> Pb<br />

Wise et al.<br />

(2005)<br />

Martins et al.<br />

(1993)


AX5-88<br />

Compound<br />

Table AX5-6.7. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell Cultures DNA Damage<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate DNA strand breaks as nucleiod<br />

sedimentation (500 µM <strong>for</strong> 20–<br />

25 h)<br />

Pb acetate DNA strand breaks as nucleoid<br />

sedimentation assay (100 µM<br />

<strong>for</strong> 30 min–4 h)<br />

Pb chromate DNA adducts (0.4–0.8 µg/cm 2<br />

<strong>for</strong> 24 h)<br />

Pb chromate DNA double strand breaks<br />

(0.1–5 µg/cm 2 <strong>for</strong> 24 h) by<br />

Comet assay and H2A.X foci<br />

<strong>for</strong>mation<br />

Pb acetate DNA strand breaks and DNA<br />

protein crosslinks and oxidative<br />

lesions by comet assay (1–<br />

100 µM <strong>for</strong> 1 h)<br />

Cell Type and<br />

Culture Medium Co-exposure Effects Reference<br />

HeLa Cells in AMEM<br />

+ 5% FBS<br />

HeLa Cells in<br />

HEPES/<br />

glucose buffer<br />

Primary Human Small<br />

<strong>Air</strong>way Cells in<br />

Clonetics growth<br />

medium<br />

WTHBF-6—human<br />

lung cells with<br />

hTERT in<br />

DMEM/F12 + 15%<br />

CCS<br />

Primary lymphocytes<br />

in RPMI 1640 without<br />

serum<br />

None<br />

See also Table<br />

AX5-6.16<br />

Buthionine<br />

sulfoximine (BSO) to<br />

deplete cells <strong>of</strong> thiols<br />

Pb acetate alone did not induce single strand breaks. Hartwig et al.<br />

(1990)<br />

Pb acetate did not induce DNA strand breaks. Snyder and<br />

Lachmann<br />

(1989)<br />

None Pb chromate induced Pb inclusion bodies and Cr-DNA adducts and<br />

Pb-DNA adducts in a concentration-dependent manner.<br />

None Pb chromate induced DNA double strand breaks in a concentration<br />

dependent manner.<br />

This study showed the damage was due to chromate and not Pb.<br />

Vitamins A (10 µM),<br />

C (10 µM), E<br />

(25 µM), calcium<br />

chloride (100 µM)<br />

magnesium chloride<br />

(100 µM) or zinc<br />

chloride (100 µM)<br />

Pb acetate induced an increase in DNA single strand breaks at 1 µM<br />

that went down with increasing dose. The highest concentration was<br />

significantly less than the damage in untreated controls. For double<br />

strand breaks, all concentrations had more damage than the controls,<br />

but there was less damage in the highest concentrations than the two<br />

lower ones. Pb only induced a slight increase in the amount <strong>of</strong> DNAprotein<br />

crosslinks at the highest concentration.<br />

Co-exposure to magnesium had no effect. Co-exposure to vitamins A,<br />

C, and E or zinc exacerbated the DNA single strand break effects at the<br />

highest concentration. Co-exposure to calcium exacerbated the single<br />

strand break effect at all concentrations.<br />

Singh et al.<br />

(1999)<br />

Xie et al.<br />

(2005)<br />

Woźniak and<br />

Blasiak (2003)


AX5-89<br />

Table AX5-6.7 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Human Cell Cultures DNA Damage<br />

Compound<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb nitrate DNA-protein crosslinks by<br />

SDS precipitation<br />

(1–10 mM <strong>for</strong> 6 h)<br />

Cell Type and<br />

Culture Medium Co-exposure Effects Reference<br />

Human Burkitt’s<br />

lymphoma cells–EBV<br />

trans<strong>for</strong>med in RPMI<br />

1640 + 10% FCS<br />

Abbreviations<br />

hTERT is the catalytic subunit <strong>of</strong> human telomerase.<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

DMEM/F12—Dulbecco’s Minimal Essential Medium/Ham’s F12;<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

None Pb nitrate did not induced DNA protein crosslinks. Independent<br />

samples were analyzed by 5 different laboratories.<br />

Costa et al.<br />

(1996)


AX5-90<br />

Table AX5-6.8. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures Mutagenicity<br />

Compound Assay and Duration Cell Type Co-exposure Effects Reference<br />

Pb acetate Cytotoxicity (1–25 µM <strong>for</strong> 24 h)<br />

Mutagenesis—HPRT (0.5–5 µM <strong>for</strong> 44 h)<br />

Pb acetate<br />

—insoluble<br />

precipitate at high<br />

dose.<br />

Cytotoxicity (0.5–2000 µM <strong>for</strong> 5 days)<br />

Mutagenesis—gpt (0.5–1700 µM <strong>for</strong> 5 days)<br />

Pb chloride Cytotoxicity (0.1–1 µM <strong>for</strong> 1 h)<br />

Mutagenicity—gpt assay<br />

(0.1–1 µM <strong>for</strong> 1 h)<br />

Pb chloride Cytotoxicity (0.1–1 µM <strong>for</strong> 1 h)<br />

Mutagenicity—gpt assay<br />

(0.1–1 µM <strong>for</strong> 1 h)<br />

Pb chloride Mutagenicity—gpt assay<br />

(0.1–1 µM <strong>for</strong> 1 h)<br />

PCR/Southern to analyze mutants <strong>for</strong><br />

sequence<br />

Pb chromate Cytotoxicity (10–100 µM <strong>for</strong> 24 h)<br />

HGPRT assay (10–100 µM <strong>for</strong> 24 h)<br />

Pb chromate Mutagenicity as Sodium/potassium ATPase<br />

(ouabain resistance) or 6-thioguanine<br />

resistance (25–100 µM <strong>for</strong> 5 h)<br />

V79 in AMEM + 10%<br />

FBS<br />

G12–CHV79 cells<br />

with 1 copy gpt gene<br />

in Ham’s F12 + 5%<br />

FBS<br />

AS52-CHO-gpt, lack<br />

hprt in HBSS<br />

followed by Ham’s<br />

F12 + 5% FBS<br />

AS52-CHO-gpt, lack<br />

hprt in HBSS<br />

followed by Ham’s<br />

F12 + 5% FBS<br />

AS52-CHO-gpt, lack<br />

hprt in HBSS<br />

followed by Ham’s<br />

F12 + 5% FBS<br />

V79 CHL–HPRT low<br />

clone in MEM + 10%<br />

FCS<br />

C3H10T1/2 cells in<br />

EMEM + 10% FBS<br />

None<br />

See also<br />

Table AX5-6.16<br />

See also Table<br />

AX5-6.17<br />

LC50 = 3 µM<br />

Pb acetate alone was not mutagenic.<br />

LC50 = 1700 µM<br />

Pb acetate was mutagenic, but only at toxic<br />

concentration (1700 µM) where precipitate <strong>for</strong>med<br />

not at lower concentrations (500 or 1000 µM).<br />

There were no statistical analyses <strong>of</strong> these data.<br />

None LC74 = 1 µM (maximum concentration tested)<br />

Allopurinol (50 µM)<br />

to inhibit xanthine<br />

oxidase<br />

Pb chloride induced a dose-dependent increase in<br />

the number <strong>of</strong> 6 thioguanine resistant mutants.<br />

Did not adjust and compare as previous studies.<br />

LC74 = 1 µM. Allopurinol had no effect on<br />

cytotoxicity.<br />

Pb chloride was mutagenic (0.8 and 1 µM).<br />

Allopurinol reduced mutagenesis.<br />

None Pb chloride (0.1–0.4 µM) caused mostly point<br />

mutations. Higher concentrations (0.5–1 µM)<br />

caused more deletions.<br />

There were no statistical analyses <strong>of</strong> these data.<br />

Usually examined fewer mutations than control.<br />

NTA Mutagenesis was assessed with HGPRT assay. Pb<br />

chromate was not mutagenic.<br />

Co-exposure to NTA caused Pb chromate to<br />

become mutagenic through increased solubilization.<br />

This mutagenic effect was completely attributed to<br />

the Cr(VI) ions.<br />

Hartwig et al.<br />

(1990)<br />

Roy and Rossman<br />

(1992)<br />

Ariza et al. (1996)<br />

Ariza et al. (1998)<br />

Ariza and Williams<br />

(1999)<br />

Celotti et al. (1987)<br />

None Pb chromate was not mutagenic. Patierno et al.<br />

(1988) and Patierno<br />

and Landolph<br />

(1989) (both papers<br />

present the same<br />

data)


AX5-91<br />

Table AX5-6.8 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures Mutagenicity<br />

Compound Assay and Duration Cell Type Co-exposure Effects Reference<br />

Pb nitrate<br />

Precipitate at 1000<br />

µM and higher.<br />

Pb nitrate<br />

-no insoluble<br />

precipitate<br />

Cytotoxicity (50–5,000 µM <strong>for</strong> 5 days)<br />

Mutagenesis at HPRT locus<br />

(50–2,000 µM <strong>for</strong> 5 days)<br />

Cytotoxicity (0.5–2000 µM <strong>for</strong> 5 days)<br />

Mutagenesis—gpt (0.5–1700 µM <strong>for</strong> 5 days)<br />

Pb sulfide Cytotoxicity (100–1,000 µM <strong>for</strong> 24 h)<br />

Mutagenicity at HPRT locus<br />

(100–1,000 µM <strong>for</strong> 24 h)<br />

V79 CHL–HPRT low<br />

clone in Ham’s F12<br />

+10% FBS<br />

G12–CHV79 cells<br />

with 1 copy gpt gene<br />

in Ham’s F12 + 5%<br />

FBS<br />

V79 CHL–HPRT low<br />

clone in Ham’s F12<br />

+10% FBS<br />

None LC50 = 2950 µM<br />

Pb nitrate was mutagenic at 500 µM, but there was<br />

no dose response as higher doses less mutagenic<br />

though still 2–4-fold higher. There were no<br />

statistical analyses <strong>of</strong> these data.<br />

See also Table<br />

AX5-6.17<br />

Abbreviations<br />

V79 are a Chinese Hamster Lung Cell Line;<br />

G12–CHV79 are derived from V79;<br />

CHO are a Chinese Hamster Ovary Cell Line ;<br />

AS52 are derived from CHO;<br />

C3H10T/12 cells are a mouse embryo cell line<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

HBSS—Hank’s Balanced Salt Solution<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

LC 50 = 1500 µM<br />

Pb nitrate was not mutagenic. There were no<br />

statistical analyses <strong>of</strong> these data.<br />

None LC50 = 580 µM; did not increase with longer<br />

exposures.<br />

Mutagenic at 376 and 563 µM. Not mutagenic<br />

lower or higher. Suggested cytotoxicity prevented<br />

mutagenesis at higher concentrations. There were<br />

no statistical analyses <strong>of</strong> these data.<br />

Zelik<strong>of</strong>f et al.<br />

(1988)<br />

Roy and Rossman<br />

(1992)<br />

Zelik<strong>of</strong>f et al.<br />

(1988)


AX5-92<br />

Compound<br />

Table AX5-6.9. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures Clastogenicity<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb chromate Chromosome Aberrations<br />

(0.4–8 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome Aberrations<br />

(0.8–8 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome Aberrations<br />

(0.8 or 8 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb chromate Chromosome Aberrations<br />

(0.8–8 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb glutamate Chromosome Aberrations<br />

(500–2,000 µM <strong>for</strong> 24 h)<br />

Pb nitrate Chromosome Aberrations<br />

(500–2,000 µM <strong>for</strong> 24 h)<br />

Insoluble precipitate at all<br />

concentrations<br />

Pb nitrate Chromosome Aberrations<br />

(3–30 µM <strong>for</strong> 2 h +16 h recovery)<br />

Pb nitrate Chromosome aberrations<br />

(0.05–1 µM <strong>for</strong> 3–12 h)<br />

Cell Type and Culture<br />

Medium Co-exposure Effects Reference<br />

Chinese Hamster Ovary AA8<br />

cells in AMEM + 10% FBS<br />

Chinese Hamster Ovary AA8<br />

cells in AMEM + 10% FBS<br />

Chinese Hamster Ovary AA8<br />

cells in AMEM + 10% FBS<br />

Chinese Hamster Ovary AA8<br />

cells in AMEM + 10% FBS<br />

Chinese Hamster Ovary AA8<br />

cells in AMEM + 10% FBS<br />

Chinese Hamster Ovary AA8<br />

cells in AMEM + 10% FBS<br />

Chinese Hamster Ovary cells<br />

in EMEM + 10% FBS<br />

Chinese Hamster Ovary AA8<br />

cells in DMEM +10% NCS<br />

None Pb chromate induced chromosome damage in a<br />

concentration dependent manner.<br />

This study was focused on chromate.<br />

Vitamin C (1 mM <strong>for</strong><br />

24 h as co-exposure to<br />

block Cr uptake)<br />

Vitamin E (25 µM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Vitamin C (1 mM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Vitamin E (25 µM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Vitamin E (25 µM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Vitamin E (25 µM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Pb chromate induced chromosome damage in a<br />

concentration dependent manner. This effect and uptake<br />

<strong>of</strong> Cr ions were blocked by vitamin C.<br />

This study was focused on chromate.<br />

Pb chromate induced chromosome damage in a<br />

concentration dependent manner. Vitamin E blocked<br />

clastogenic activity <strong>of</strong> Pb chromate, but had no effect on<br />

other Pb compounds.<br />

This study found that the chromosome damage was<br />

mediated by chromate ions and not Pb ions<br />

Pb chromate induced chromosome damage in a<br />

concentration dependent manner. Vitamins C and E<br />

blocked clastogenic activity <strong>of</strong> Pb chromate.<br />

This study was focused on chromate.<br />

Pb glutamate induced chromosome damage at 1 mM but<br />

not at higher or lower concentrations.<br />

Vitamin E did not modify this effect.<br />

Wise et al.<br />

(1992)<br />

Wise et al.<br />

(1993)<br />

Wise et al.<br />

(1994)<br />

Blankenship<br />

et al. (1997)<br />

Wise et al.<br />

(1994)<br />

Pb nitrate did not induce chromosome damage. Wise et al.<br />

(1994)<br />

None Pb nitrate did not induce chromosome damage. Lin et al.<br />

(1994)<br />

Crown ethers to<br />

modify effect through<br />

chelation and uptake<br />

Pb nitrate did not induce chromosome damage. Cai and<br />

Arenaz<br />

(1998)


AX5-93<br />

Table AX5-6.9 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures Clastogenicity<br />

Compound<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate SCE (1–10 µM <strong>for</strong> 26 h+) V79 in AMEM + 10% FBS None<br />

See also<br />

Table AX5-6.17<br />

Pb acetate Micronucleus assay<br />

(0.01–10 µM <strong>for</strong> 18 h)<br />

Pb nitrate SCE Formation (500–3,000 µM <strong>for</strong><br />

24 h)<br />

Precipitate at 1000 µM and higher.<br />

Pb nitrate Micronucleus <strong>for</strong>mation<br />

(3–30 µM <strong>for</strong> 2 h +16 h recovery)<br />

SCE (3–30 µM <strong>for</strong> 2 h +16 h recovery)<br />

Cell Type and Culture<br />

Medium Co-exposure Effects Reference<br />

Chinese Hamster V79 cells in<br />

DMEM + 10% FCS<br />

V79 CHL–HPRT low clone in<br />

Ham’s F12 +10% FBS<br />

CHO cells in EMEM + 10%<br />

FBS<br />

Pb nitrate SCE (0.05–1 µM <strong>for</strong> 3–12 h) CHO AA8 in DMEM +10%<br />

NCS<br />

Pb acetate alone did not induce SCE. Only 25 cells per<br />

treatment analyzed.<br />

None Pb acetate induced an increase in micronuclei that<br />

increased with concentration and reached a plateau.<br />

Two experiments were done and presented separately as a<br />

Figure and a Table. The magnitude <strong>of</strong> the effects was<br />

small to modest and statistics were not done.<br />

Hartwig<br />

et al. (1990)<br />

Bonacker<br />

et al. (2005)<br />

None No SCE. Only 30 cells analyzed per treatment. Zelik<strong>of</strong>f<br />

et al. (1988)<br />

None Pb nitrate did not induce micronuclei <strong>for</strong>mation<br />

Pb nitrate induces a concentration-dependent increase in<br />

SCE (3, 10, 30 µM).<br />

Crown ethers to<br />

modify effect<br />

through chelation<br />

and uptake<br />

Pb nitrate caused a weak concentration-dependent<br />

increase in SCE. These data were not statistically<br />

analyzed. The effect was reduced by a crown ether<br />

probably because a similar reduction was seen in<br />

spontaneous SCE.<br />

Lin et al.<br />

(1994)<br />

Cai and<br />

Arenaz<br />

(1998)


AX5-94<br />

Table AX5-6.9 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures Clastogenicity<br />

Compound<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb sulfide SCE Formation<br />

(100–1,000 µM <strong>for</strong> 24 h)<br />

Cell Type and Culture<br />

Medium Co-exposure Effects Reference<br />

V79 CHL–HPRT low clone in<br />

Ham’s F12 +10% FBS<br />

Abbreviations<br />

V79 are a Chinese Hamster Lung Cell Line;<br />

CHO are a Chinese Hamster Ovary Cell Line ;<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

DMEM—Dulbecco’s Minimal Essential Medium;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

HBSS—Hank’s Balanced Salt Solution<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

NCS—Newborn Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

None No SCE. Only 30 cells analyzed per treatment. Zelik<strong>of</strong>f et al.<br />

(1988)


AX5-95<br />

Table AX5-6.10. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures DNA Damage<br />

Compound Assay (Concentration<br />

and Exposure Time) Cell Type and Culture Medium Co-exposure Effects Reference<br />

Pb acetate DNA damage as alkaline<br />

elution (exposure time and<br />

dose not given)<br />

Precipitate at 1000 µM and<br />

higher.<br />

Pb acetate DNA strand breaks as nick<br />

translation (1700 µM <strong>for</strong><br />

5 days)<br />

Or supercoiled relaxation<br />

(1000 µM <strong>for</strong> 5 days)<br />

Insoluble precipitate at high<br />

dose.<br />

Pb chromate DNA damage as alkaline<br />

elution (0.4–8 µg/cm 2 <strong>for</strong><br />

24 h plus 24 recovery)<br />

Pb chromate DNA adducts<br />

(0.8 or 8 µg/cm 2 <strong>for</strong> 24 h)<br />

Pb nitrate DNA Protein Crosslinks as<br />

SDS precipitation<br />

(50–5,000 µM <strong>for</strong> 4 h)<br />

V79 CHL–HPRT low clone in Ham’s<br />

F12 +10% FBS<br />

G12–CHV79 cells with 1 copy gpt<br />

gene in Ham’s F12 + 5% FBS<br />

Chinese Hamster Ovary AA8 cells in<br />

AMEM + 10% FBS<br />

Chinese Hamster Ovary AA8 cells in<br />

AMEM + 10% FBS<br />

None No DNA damage (Single strand breaks, DNAprotein<br />

crosslinks or DNA-DNA crosslinks).<br />

However, the data was not shown<br />

See also Table<br />

AX5-6.17<br />

Pb acetate did not induce SSB. Pb acetate<br />

(1700 µM) did increase nick translation when an<br />

exogenous polymerase was added. There were no<br />

statistical analyses <strong>of</strong> these data.<br />

None Pb chromate induced DNA single strand breaks in<br />

a concentration dependent manner, which were all<br />

repaired by 24 h post-treatment.<br />

Pb chromate induced DNA protein crosslinks in a<br />

concentration dependent manner, which persisted<br />

at 24 h post-treatment.<br />

Pb chromate did not induce DNA-DNA<br />

crosslinks.<br />

This study was focused on chromate.<br />

Vitamin C (1 mM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Vitamin E (25 µM as<br />

pretreatment <strong>for</strong> 24 h)<br />

Pb chromate induced DNA adducts in a<br />

concentration dependent manner. Vitamins C and<br />

E blocked DNA adducts induced by Pb chromate.<br />

This study was focused on chromate.<br />

Novik<strong>of</strong>f ascites hepatoma cells None Pb nitrate induced DNA protein crosslinks in a<br />

concentration dependent manner.<br />

Zelik<strong>of</strong>f et al. (1988)<br />

Roy and Rossman<br />

(1992)<br />

Xu et al. (1992)<br />

Blankenship et al.<br />

(1997)<br />

Wedrychowski et al.<br />

(1986)


AX5-96<br />

Table AX5-6.10 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Animal Cell Cultures DNA Damage<br />

Compound Assay (Concentration and<br />

Exposure Time)<br />

Pb nitrate DNA strand breaks as nick<br />

translation (1700 µM <strong>for</strong> 5 days)<br />

Abbreviations<br />

G12–CHV79 are derived from V79;<br />

V79 are a Chinese Hamster Lung Cell Line;<br />

CHO are a Chinese Hamster Ovary Cell Line ;<br />

Cell Type and Culture<br />

Medium Co-exposure Effects Reference<br />

G12–CHV79 cells with 1 copy<br />

gpt gene in Ham’s F12 + 5%<br />

FBS<br />

See also Table<br />

AX5-6.17<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

Pb nitrate (1700 µM) did increase nick translation when an<br />

exogenous polymerase was added. There were no statistical<br />

analyses <strong>of</strong> these data.<br />

Roy and Rossman<br />

(1992)


AX5-97<br />

Table AX5-6.11. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity Non-mammalian Cultures<br />

Compound Assay and Concentration Cell Type Co-exposure Effects Reference<br />

Pb chromate<br />

(and 13<br />

pigments<br />

containing Pb<br />

chromate)<br />

Mutation Frequency (50–500 µg/plate)<br />

Anchorage Independence <strong>for</strong> cells isolated<br />

during morphological trans<strong>for</strong>mation<br />

Neoplastic Trans<strong>for</strong>mation <strong>for</strong> cells<br />

isolated during morphological<br />

trans<strong>for</strong>mation<br />

Salmonella<br />

typhimurium +/- S9<br />

fraction<br />

Nitrilotriacetic acid<br />

(NTA to dissolve<br />

insoluble compounds)<br />

and Silica<br />

Encapsulation<br />

Pb chromate and its related pigments did not induce<br />

mutagenicity.<br />

A few did when dissolved in NTA.<br />

Encapsulation prevented mutagenesis in those that<br />

were positive when dissolved in NTA.<br />

S9 had no effect.<br />

Studied as a chromate compound.<br />

Connor and Pier<br />

(1990)


AX5-98<br />

Table AX5-6.12. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity as it Pertains to Potential Developmental Effects<br />

Compound Assay and Concentration Species Co-exposure Effects Reference<br />

Pb acetate 25–400 mg/kg given i.p as single injection<br />

and animals studied after 24 h<br />

Sperm morphology<br />

Pb acetate 200 or 400 mg/kg given by gavage daily<br />

<strong>for</strong> 5 days<br />

5 animals per group<br />

Sperm Morphology<br />

Male Swiss Mice—<br />

9–12 wks old<br />

Male Swiss Mice—<br />

9–12 wks old<br />

None Pb induced sperm head abnormalities at 50–<br />

100 mg/kg. A lower dose was negative and higher<br />

doses were not done.<br />

Calcium chloride (40 or<br />

80 mg/kg by gavage<br />

daily <strong>for</strong> 3 days given<br />

2 wks after Pb<br />

exposure)<br />

Pb induced sperm abnormalities at 200 and 400<br />

mg/kg. A lower dose was negative and higher doses<br />

were not done. Calcium appeared to block this effect.<br />

Fahmy (1999)<br />

Aboul-Ela (2002)


AX5-99<br />

Table AX5-6.13. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Genotoxicity as it Pertains to<br />

Potential Developmental Effects—Children<br />

Compound Exposure Regimen Species Co-exposure Effects Reference<br />

Pb chloride Administered in drinking water<br />

1.33 g/L <strong>for</strong> 6 wks<br />

Pb nitrate 12.5–75 mg/kg given i.v. on 9th day<br />

<strong>of</strong> gestation <strong>for</strong> 9 days.<br />

Mothers and fetuses analyzed on<br />

G18.<br />

5 animals per group<br />

Resorptions, fetal viability, and<br />

chromosome damage in the mother<br />

and fetus were examined.<br />

Pb nitrate 100–200 mg/kg given i.v. on 9th<br />

day <strong>of</strong> gestation <strong>for</strong> 9 days.<br />

Mothers and fetuses analyzed on<br />

G18.<br />

Group size not given.<br />

Resorptions, fetal viability and<br />

chromosome damage, SCE and<br />

NOR in the mother and fetus were<br />

examined. Mother–bone marrow;<br />

fetus liver or lung<br />

3 mothers and fetuses per dose were<br />

analyzed.<br />

Male NMRI<br />

Mice—9 wks old<br />

ICR Swiss Webster<br />

Mice—6–8 wks old<br />

ICR Swiss Webster<br />

Mice—6–8 wks old<br />

Cyclophosphamide—<br />

120 mg/kg b.w. given<br />

i.p 7 days prior to start<br />

<strong>of</strong> breeding<br />

Pb did not increase resorptions indicating no dominant lethal<br />

mutagenic effect. Pb appeared to have a small, but statistically<br />

insignificant reduction in the number <strong>of</strong> resorptions.<br />

Cyclophosphamide reduced live implants in female mice.<br />

None 12.5–50 mg/kg had no effect on resorption or fetal viability.<br />

75 mg/kg demonstrated some increased resorption though<br />

statistics were not done.<br />

No chromosome damage was seen in untreated controls. A low<br />

level 1-3 and 2-5 aberrations were seen in mothers and fetuses<br />

respectively.<br />

There was no dose response and no statistical analyses. Data<br />

interpretation is also complicated as too few metaphases were<br />

analyzed 20–40 total.<br />

No descriptions <strong>of</strong> potential effects on maternal health parameters<br />

or fetal weights.<br />

No indication <strong>of</strong> how many animals included in the chromosomal<br />

analysis.<br />

None Pb levels were found in both mother and fetus indicating no<br />

problems crossing the placenta.<br />

All doses indicated increased resorption and decreased placental<br />

weights. No effects on fetal weight.<br />

Significant increase in SCE in mothers at 150 and 200 mg/kg.<br />

No increase in SCE in fetuses.<br />

Significant decrease in NOR in both mother and fetuses.<br />

No gaps or breaks in mothers or fetuses.<br />

Some weak aneuploidy at lowest dose.<br />

Some karyotypic chromosome damage was seen. No explanation<br />

<strong>of</strong> how many cells analyzed per animal (3 animals per dose were<br />

analyzed) as only 20–40 cells were analyzed.<br />

There was no dose response and no statistical analyses <strong>for</strong><br />

chromosome damage. No details on how many animals analyzed<br />

<strong>for</strong> metaphase damage or how many cells per animal.<br />

Data interpretation is also complicated as too few metaphases<br />

were analyzed 10–25 <strong>for</strong> SCE. Not given <strong>for</strong> CA.<br />

No detail on potential maternal toxicity.<br />

Kristensen et al.<br />

(1993).<br />

Nayak et al.<br />

(1989a)<br />

Nayak et al.<br />

(1989b)


AX5-100<br />

Table AX5-6.14. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture Interactions—Animal<br />

Compound Exposure Regimen Species Co-exposure Effects Reference<br />

Pb acetate Administered as an i.p. injection <strong>of</strong><br />

100 µl/kg.<br />

Animals were studied either 24 h<br />

after a daily dose <strong>for</strong> 3 days or <strong>for</strong><br />

various times (5 min–48 h) after a<br />

single dose.<br />

Pb nitrate Administered as an i.p. injection <strong>of</strong><br />

100 µmol/kg.<br />

Animals were studied either 24 h<br />

after a daily dose <strong>for</strong> 3 days or <strong>for</strong><br />

various times (5 min–48 h) after a<br />

single dose.<br />

Pb nitrate Administered as an i.p. injection <strong>of</strong><br />

100 µmol/kg. Some rats were<br />

partially hepatectomized.<br />

Animals were studied 48 h after<br />

injection.<br />

Pb nitrate Administered as an i.v. injection <strong>of</strong><br />

20, 50, or 100 µmol/kg.<br />

Animals were studied 24 h after<br />

injection.<br />

Male Wistar Rats—<br />

10 wks old<br />

Male Wistar Rats—<br />

10 wks old<br />

Male Sprague<br />

Dawley rats<br />

Male Fisher 344<br />

rats—7 wks old<br />

Actinomycin D<br />

(0.8 mg/kg)<br />

administered i.p. <strong>for</strong><br />

4 h be<strong>for</strong>e a single<br />

dose <strong>of</strong> Pb acetate.<br />

Actinomycin D<br />

(0.8 mg/kg)<br />

administered i.p. <strong>for</strong><br />

4 h be<strong>for</strong>e a single<br />

dose <strong>of</strong> Pb acetate.<br />

Pb acetate induced GST-P, which required the cis element, GPEI<br />

(GST-P enhancer I).<br />

Actinomycin D blocked the effects indicating that regulation was<br />

at the mRNA level.<br />

Pb acetate induced c-jun, which exhibited three peaks <strong>of</strong> exposure<br />

over 48 h.<br />

Pb acetate was more potent than Pb nitrate.<br />

Pb nitrate induced GST-P, which required the cis element, GPEI<br />

(GST-P enhancer I).<br />

Actinomycin D blocked the effects indicating that regulation was<br />

the mRNA level.<br />

Pb nitrate induced c-jun, which exhibited three peaks <strong>of</strong> exposure<br />

over 48 h.<br />

Pb nitrate was less potent than Pb acetate.<br />

Partial Hepatectomy Pb nitrate induced GSH and GST 7-7 activity.<br />

Partial hepatectomy did not induce GSH or GST 7-7.<br />

2-methoxy-<br />

4-aminobenzene to<br />

induce P4501A2<br />

or<br />

3-methylcholanthrene<br />

to induce 4501A1<br />

Pb nitrate selectively inhibited P4501A2 and its induction by 2methoxy-4-aminobenzene<br />

at the mRNA and protein level in a<br />

dose-dependent manner.<br />

Pb nitrate had minimal effect on P4501A1 and its induction by 3-<br />

methyl cholanthrene.<br />

Pb nitrate did not affect microsomal activity.<br />

Pb nitrate induced GST-P in a dose-dependent manner.<br />

Suzuki et al.<br />

(1996)<br />

Suzuki et al.<br />

(1996)<br />

Dock (1989)<br />

Degawa et al.<br />

(1993)


AX5-101<br />

Compound<br />

Table AX5-6.15. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture Interactions—Human<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate Tyrosine aminotransferase<br />

expression and activity<br />

(0.3–10 µM <strong>for</strong> 24–48 h)<br />

PKC activity: 10 µM <strong>for</strong> 48 h<br />

Pb nitrate EROD/MROD activity<br />

(10–100 µM <strong>for</strong> 24 h)<br />

NAD(P)H: quinone<br />

oxidoreductase activity<br />

(10–100 µM <strong>for</strong> 24 h)<br />

Glutathione-S-transferase<br />

Ya activity (10–100 µM <strong>for</strong> 24 h)<br />

Pb nitrate NAD(P)H: quinone<br />

oxidoreductase activity<br />

(25 µM <strong>for</strong> 24 h)<br />

Glutathione-S-transferase Ya<br />

activity (25 µM <strong>for</strong> 24 h)<br />

Abbreviations<br />

Medium and Components<br />

DMEM—Dulbecco’s Minimal Essential Medium;<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Cell Type<br />

and Culture<br />

Medium Co-exposure Effects Reference<br />

H4-<strong>II</strong>E-C3—<br />

human<br />

hepatoma cells<br />

in DMEM +<br />

2.5% FCS<br />

Hepa 1c1c7<br />

wild type cells<br />

in DMEM +<br />

10% FBS<br />

C12- AHRdeficient<br />

Hepa<br />

1c1c7 cells in<br />

DMEM + 10%<br />

FBS<br />

Dexamethasone<br />

(0.1 µM <strong>for</strong> 16 h),<br />

or calcium chloride<br />

(10 µM) or genistein<br />

(100 µM to block PKC<br />

activity)<br />

TCDD (0.1 nM),<br />

3-methyl cholanthrene<br />

(0.25 µM), betanaptflavone<br />

(10 µM),<br />

benzo(a)pyrene (1 µM)<br />

TCDD (0.1 nM),<br />

3-methyl cholanthrene<br />

(0.25 µM), betanaptflavone<br />

(10 µM),<br />

benzo(a)pyrene (1 µM)<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

Pb acetate inhibited glucocorticoid –induction <strong>of</strong> tyrosine<br />

aminotransferase in a time- and dose-dependent manner.<br />

Co-treatment with calcium reduced the effects <strong>of</strong> Pb.<br />

Co-treatment with genistein increased the effects <strong>of</strong> Pb.<br />

Pb acetate decreases PKC activity and its translocation from the<br />

cytosol to the particulate cellular fraction.<br />

Pb did not affect EROD/MROD activity.<br />

Pb reduced CYP1A1 induction by TCDD, 3-methyl cholanthrene,<br />

beta-naptflavone, benzo(a)pyrene.<br />

Pb increased NAD(P)H: quinone oxidoreductase activity<br />

Pb increased NAD(P)H: quinone oxidoreductase activity induction by<br />

TCDD, 3-methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.<br />

10 µM increased Glutathione-S-transferase Ya activity.<br />

25 and 100 µM increased Glutathione-S-transferase Ya activity.<br />

Pb nitrate did not affect Glutathione-S-transferase Ya induction by<br />

TCDD, 3-methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.<br />

Pb nitrate did not increase NAD(P)H: quinone oxidoreductase and<br />

Glutathione-S-transferase Ya activity<br />

Pb increased NAD(P)H: quinone oxidoreductase activity induction by<br />

TCDD, 3-methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.<br />

Pb did not affect Glutathione-S-transferase Ya induction by TCDD, 3methyl<br />

cholanthrene, beta-naptflavone, benzo(a)pyrene.<br />

Tonner and Heiman<br />

(1997)<br />

Korashy and<br />

El-Kadi (2004)<br />

Korashy and<br />

El Kadi (2004)


AX5-102<br />

Compound<br />

Table AX5-6.16. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture<br />

Interactions—DNA Repair—Human<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate DNA strand breaks as nucleoid<br />

sedimentation (500 µM <strong>for</strong><br />

20–25 h)<br />

Abbreviations<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

FBS—Fetal Bovine Serum<br />

Cell Type<br />

and Culture<br />

Medium Co-exposure Effects Reference<br />

HeLa Cells in<br />

AMEM + 5%<br />

FBS<br />

UV (5 J/m 2 ) Pb acetate alone did not induce single strand breaks. UV did induce<br />

strand breaks. Co-exposure <strong>of</strong> Pb and UV cause DNA strand breaks to<br />

persist longer suggesting an inhibition <strong>of</strong> repair.<br />

Hartwig et al.<br />

(1990)


AX5-103<br />

Compound<br />

Table AX5-6.17. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Epigenetic Effects and Mixture<br />

Interactions—DNA Repair—Animal<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate Cytotoxicity (0.5–5 µM <strong>for</strong> 24 h)<br />

Mutagenesis—HPRT (0.5–5 µM<br />

<strong>for</strong> 44h)<br />

SCE (1–10 µM <strong>for</strong> 26 h+)<br />

Pb acetate Mutagenesis—gpt<br />

(0.5–1700 mM <strong>for</strong> 24 h)<br />

DNA strand breaks as<br />

supercoiled relaxation<br />

(1000 mM <strong>for</strong> 24 h)<br />

Abbreviations<br />

G12–CHV79 are derived from V79;<br />

V79 are a Chinese Hamster Lung Cell Line;<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

FBS—Fetal Bovine Serum<br />

Cell Type<br />

and Culture<br />

Medium Co-exposure Effects Reference<br />

V79 in<br />

AMEM + 10%<br />

FBS<br />

G12–CHV79<br />

cells with 1<br />

copy gpt gene<br />

in Ham’s F12<br />

+ 5% FBS<br />

UV (5 J/m 2 ) Pb acetate ( 3 and 5 µM) increased UV-induced increased cytotoxicity<br />

with no dose response (plateau). There were no statistical analyses <strong>of</strong><br />

these data.<br />

Pb acetate (0.5–5 µM) increased UV mutagenicity though with no<br />

dose response (plateau). There were no statistical analyses <strong>of</strong> these<br />

data<br />

Pb acetate (1–10 µM) increased UV-induced SCE. Significant at<br />

p < 0.01. Only 25 cells per treatment analyzed.<br />

UV (2 J/m 2 ), or MNNG<br />

(0.5 µg/L)<br />

Pb acetate was co-mutagenic with UV and MNNG increasing<br />

frequency 2-fold.<br />

Pb acetate does not increase strand breaks induced by UV.<br />

Hartwig et al. (1990)<br />

Roy and Rossman<br />

(1992)


AX5-104<br />

Table AX5-6.18. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis—Animal<br />

Compound Exposure Regimen Species Co-exposure Effects Reference<br />

Pb acetate Administered Pb acetate (12.5 mg/kg) i.p.<br />

Animals studied 24 h after injection.<br />

Pb nitrate Liver initiation induced by the resistant hepatocyte<br />

model<br />

Initiation followed by i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg ) or partial hepatectomy<br />

Studied DNA synthesis (30 h after injection) and<br />

preneoplastic nodule <strong>for</strong>mation<br />

(5 wks after injection)<br />

Pb nitrate Liver initiation induced by the resistant hepatocyte<br />

model (diethylnitrosamine followed by 2acetylamin<strong>of</strong>luorene<br />

plus carbon tetrachloride)<br />

Initiation followed by i.v. injection <strong>of</strong> 4 doses <strong>of</strong> Pb<br />

nitrate (100 µM/kg ) given once every 20 days or<br />

partial hepatectomy, ethylene dibromide, or<br />

nafenopine<br />

Animal were evaluated <strong>for</strong> preneoplastic foci at 75 or<br />

155 days after initiation.<br />

Pb nitrate Liver initiation induced by the orotic acid model<br />

(diethylnitrosamine plus orotic acid)<br />

Initiation followed by i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg) or partial hepatectomy, or by gavage:<br />

ethylene dibromide, or cyproterone<br />

DNA synthesis was examined at various time<br />

intervals (24 h–5 days) after injection.<br />

Male B6 Mice None Pb acetate induced TNF-alpha in glial and<br />

neuronal cells in the cerebral cortex and<br />

subcortical white matter and on Purkinje cells in<br />

the cerebellum, but did not induced apoptosis in<br />

these areas<br />

Male Wistar<br />

Rats—4 per group<br />

Male Wistar<br />

Rats—4 per group<br />

Male Wistar<br />

Rats—4 per group<br />

Partial Hepatectomy Pb nitrate stimulated DNA synthesis and liver cell<br />

proliferation<br />

Pb nitrate did not induce preneoplastic nodule.<br />

Partial hepatectomy did.<br />

Diethylnitrosamine Pb nitrate, partial hepatectomy, ethylene<br />

dibromide, or nafenopine all stimulated DNA<br />

synthesis and liver cell proliferation<br />

Pb nitrate, ethylene dibromide, or nafenopine did<br />

not induce preneoplastic nodule. Partial<br />

hepatectomy did.<br />

Diethylnitrosamine Pb nitrate, partial hepatectomy, ethylene<br />

dibromide, or cyproterone all stimulated DNA<br />

synthesis within 30 min.<br />

Pb nitrate induced DNA synthesis <strong>for</strong> 5 days.<br />

Cheng et al. (2002)<br />

Columbano et al.<br />

(1987)<br />

Columbano et al.<br />

(1990)<br />

Coni et al. (1992)


AX5-105<br />

Table AX5-6.18 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis—Animal<br />

Compound Exposure Regimen Species Co-exposure Effects Reference<br />

Pb nitrate Liver initiation induced by the resistant hepatocyte<br />

model (diethylnitrosamine followed by 2acetylamin<strong>of</strong>luorene<br />

plus carbon tetrachloride) or the<br />

phenobarbital model (diethylnitrosamine plus orotic<br />

acid), or the orotic acid model (diethylnitrosamine<br />

plus orotic acid)<br />

Initiation followed by i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg ) or partial hepatectomy, or carbon<br />

tetrachloride by gavage<br />

Animals were studied 6 wks after initiation.<br />

Pb nitrate Liver initiation induced by the resistant hepatocyte<br />

model (diethylnitrosamine followed by<br />

2-acetylamin<strong>of</strong>luorene plus carbon tetrachloride)<br />

Initiation followed by i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg ) or partial hepatectomy, or by gavage:<br />

ethylene dibromide, or cyproterone, or nafenopine<br />

Also tried either 1 or 2 additional i.v. injections <strong>of</strong> Pb<br />

over 3-day intervals.<br />

Animals were studied at various intervals (1–6 days)<br />

after injection<br />

Pb nitrate Administered as i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg ) or partial hepatectomy, or by gavage:<br />

carbon tetrachloride, or ethylene dibromide, or<br />

cyproterone, or nafenopine<br />

Animals were studied at various time intervals<br />

(0.25–24 h) after injection.<br />

Pb nitrate Administered as i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg) or partial hepatectomy, or nafenopine by<br />

gavage.<br />

Animals were studied at various time intervals<br />

(24–96 h) after injection.<br />

Pb nitrate Administered as i.v. injection <strong>of</strong> Pb nitrate<br />

(10 µM/100 g)<br />

Studies <strong>for</strong> apoptosis at 12, 24, 36, 48, 72, 96, 120,<br />

168, 336 h after injection<br />

Male Wistar<br />

rats—4 per group<br />

Male Wistar<br />

rats—4 per group<br />

Male Wistar<br />

rats—4 per group<br />

Male Wistar<br />

rats—4 per group,<br />

8 wks old<br />

Male Wistar<br />

rats—4 rats per<br />

group<br />

Partial<br />

Hepatectomy,<br />

carbon tetrachloride<br />

Diethylnitrosamine,<br />

2-AAF<br />

Partial<br />

Hepatectomy,<br />

carbon tetrachloride<br />

Pb nitrate, partial hepatectomy, carbon<br />

tetrachloride all stimulated DNA synthesis and<br />

liver cell proliferation<br />

Pb nitrate, did not induce preneoplastic nodules.<br />

Partial hepatectomy and carbon tetrachloride did.<br />

This study aimed to determine if mitogens induce<br />

nodules at different time points.<br />

Pb nitrate, ethylene dibromide, cyproterone, or<br />

nafenopine did not induce preneoplastic nodules<br />

at all. Partial hepatectomy did within 3 days.<br />

Multiple injections <strong>of</strong> Pb nitrate did not induce<br />

preneoplastic lesions.<br />

Pb nitrate, ethylene dibromide, cyproterone, or<br />

nafenopine induced c-jun and c-myc but did not<br />

induce c-fos.<br />

Partial hepatectomy and carbon tetrachloride<br />

induced c-jun, c-fos, and c-myc.<br />

None Pb nitrate induced a high incidence <strong>of</strong> polyploidy<br />

and binucleated cells. These changes were<br />

irreversible after 2 wks. Many <strong>of</strong> these cells were<br />

the newly synthesized cells.<br />

Partial hepatectomy and carbon tetrachloride<br />

induced tetraploid and octaploid mononucleated<br />

cells.<br />

None Liver weight increased until day 5 then returned to<br />

control levels.<br />

DNA synthesis peaked at 36 h<br />

Apoptosis peaked at day 4 and then decreased<br />

gradually.<br />

Ledda-Columbano<br />

et al. (1992)<br />

Coni et al. (1993)<br />

Coni et al. (1993)<br />

Melchiorri et al.<br />

(1993)<br />

Nakajima et al.<br />

(1995)


AX5-106<br />

Table AX5-6.18 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis—Animal<br />

Compound Exposure Regimen Species Co-exposure Effects Reference<br />

Pb nitrate Administered as i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg) or TNF-alpha.<br />

Animals were studied at various time intervals<br />

(12–48 h) after injection.<br />

Pb nitrate Administered after diethylnitrosamine (200 mg/kg<br />

given i.p) as i.v. injection <strong>of</strong> Pb nitrate (100 µM/kg )<br />

or instead carbon tetrachloride by gavage<br />

Animals were studied at various time intervals<br />

(3–21 days) after injection.<br />

Pb nitrate Administered as i.v. injection <strong>of</strong> Pb nitrate<br />

(100 µM/kg ) or partial hepatectomy, or by gavage:<br />

carbon tetrachloride, or cyproterone, or nafenopine<br />

Animals were studied at various time intervals<br />

(0.5–24 h) after injection.<br />

Male Wistar<br />

Rats—4 per<br />

group, 5–6 wks<br />

old<br />

Male Wistar<br />

Rats—4 per group<br />

Male Wistar<br />

Rats—8 wks old<br />

None Pb nitrate and TNF-alpha induced similar<br />

proliferative responses.<br />

Carbon<br />

tetrachloride<br />

Partial<br />

Hepatectomy,<br />

ethylene<br />

dibromide,<br />

nafenopine, or<br />

cyproterone<br />

Pb nitrate induced apoptosis affects both newly<br />

synthesized cells and non-replicative cells.<br />

Pb nitrate decreased the number and had no effect<br />

on the size <strong>of</strong> placental glutathione-S-transferase<br />

lesions. Carbon tetrachloride substantially<br />

increased these lesions both in number and in size.<br />

Pb nitrate induced NF-kB, TNF-alpha and iNOS,<br />

but not AP-1.<br />

Carbon tetrachloride induced and activated NF-kB,<br />

TNF-alpha iNOS, and AP-1.<br />

Nafenopine and cyproteone did not induce or<br />

activate NF-kB,TNF-alpha iNOS, or AP-1.<br />

Shinozuka et al.<br />

(1996)<br />

Columbano et al.<br />

(1996)<br />

Menegazzi et al.<br />

(1997)


AX5-107<br />

Compound<br />

Table AX5-6.19. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis Human and Animal Cell Culture Studies<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate Cell Proliferation (0.1–100 µM <strong>for</strong><br />

2–6 days)<br />

DNA synthesis (1–100 µM <strong>for</strong><br />

72 h)<br />

Tyrosine aminotransferase<br />

expression and activity (0.3–10 µM<br />

<strong>for</strong> 24– 48 h)<br />

Pb acetate Cell proliferation (10 µM–1mM <strong>for</strong><br />

24 h–7 days)<br />

Pb acetate Cell growth (0.01–10 µM <strong>for</strong><br />

12-72 h)<br />

Expression <strong>of</strong> genes in cytokine<br />

pathways (0.01–10 µM <strong>for</strong> 24 h)<br />

Pb acetate Cell proliferation (0.078–320 µM<br />

<strong>for</strong> 48 h)<br />

Apoptosis (1.25–80 µM)<br />

Cell cycle analysis<br />

Pb acetate DNA synthesis (1–50 µM <strong>for</strong> 24 h)<br />

Expression <strong>of</strong> genes in mitogen<br />

activated pathways (1–50 µM <strong>for</strong><br />

5 min–4 h)<br />

Pb acetate Cell proliferation (1 µM <strong>for</strong> 24 h)<br />

Cell differentiation<br />

(1 µM <strong>for</strong> 48 h)<br />

PKC activation (1 µM <strong>for</strong> 24 h)<br />

Cell Type and<br />

Culture Medium Co-exposure Effects Reference<br />

H4-<strong>II</strong>-C3—human<br />

hepatoma cells in DMEM<br />

+ 2.5% FCS<br />

REL cells—Rat Epithelial<br />

cells in Ham’s F10<br />

medium + 10% FBS<br />

U-373MG—human<br />

glioma cell line in DMEM<br />

+ 10 or 20% FBS<br />

Rat-1 fibroblasts in<br />

EMEM +10% FBS<br />

1321N1–human<br />

astrocytoma cells in<br />

DMEM + 0.1% BSA<br />

Primary oligodendrocyte<br />

progenitor cells–in<br />

DMEM + 1% FBS<br />

Dexamethasone<br />

(0.1 µM <strong>for</strong> 16 h)<br />

Pb acetate inhibited cell growth in a time- and dosedependent<br />

manner.<br />

Pb acetate inhibited DNA synthesis in a dose-dependent<br />

manner.<br />

Pb acetate alone did not inhibit tyrosine aminotransferase.<br />

Pb acetate inhibited glucocorticoid–induction <strong>of</strong> tyrosine<br />

aminotransferase in a time- and dose-dependent manner.<br />

None Pb acetate inhibited cell growth at all concentrations <strong>for</strong><br />

24 h–7 days.<br />

Pb acetate did not affect gap junction capacity, which is<br />

<strong>of</strong>ten inhibited by tumor promoters.<br />

None Pb acetate did not inhibit or enhance cell growth.<br />

Pb acetate enhanced the expression <strong>of</strong> TNF-alpha, but<br />

decreased interleukin-1 beta, interleukin-6, gammaaminobutyric<br />

acid transaminase, and glutamine synthetase<br />

under 10% FBS.<br />

Pb acetate further enhanced the expression <strong>of</strong> TNF-alpha<br />

under 20% serum, but had no effect at all on expression <strong>of</strong><br />

the other genes.<br />

None Pb acetate inhibited cell growth at 0.635–320 µM.<br />

Pb acetate induced apoptosis from 2.5–10 µM.<br />

Pb acetate caused GS/M and S-phase arrest.<br />

None Pb acetate induced DNA synthesis.<br />

Pb acetate induced activation <strong>of</strong> MAPK, ERK1. ERK2,<br />

MEK1 , MEK2, PKC, and p90 RSK .<br />

Pb acetate did not activate PI3K or p70 s6k .<br />

None Pb acetate inhibited basal and growth factor stimulated<br />

growth.<br />

Pb acetate inhibited cell differentiation in a PHC-dependent<br />

manner.<br />

Pb acetate redistributes PKC from the cytosol to the<br />

membrane, but did not increase PKC activity.<br />

Heiman and<br />

Tonner (1995)<br />

Apostoli et al.<br />

(2000)<br />

Liu et al. (2000)<br />

Iavicoli et al.,<br />

(2001)<br />

Lu et al. (2002)<br />

Deng and Poretz<br />

(2002)


AX5-108<br />

Table AX5-6.19 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis Human and Animal Cell Culture Studies<br />

Compound<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate Expression <strong>of</strong> TNF-alpha<br />

(0.1–10 µM <strong>for</strong> 24 h)<br />

Pb chloride Cell proliferation<br />

(10 µM–1mM <strong>for</strong> 24–48 h)<br />

Pb oxide Cell proliferation<br />

(10 µM–1mM <strong>for</strong> 24 h–7 days)<br />

Pb sulfate Cell proliferation<br />

(10 µM–1mM <strong>for</strong> 24–48 h)<br />

Pb chromate Apoptosis (350 µM <strong>for</strong> 24 h)<br />

Cell Type and<br />

Culture Medium Co-exposure Effects Reference<br />

U-373MG—human<br />

glioma cell line in<br />

DMEM + 20% FBS<br />

REL cells—Rat Epithelial<br />

cells in Ham’s F10<br />

medium + 10% FBS<br />

REL cells—Rat Epithelial<br />

cells in Ham’s F10<br />

medium + 10% FBS<br />

REL cells—Rat Epithelial<br />

cells in Ham’s F10<br />

medium + 10% FBS<br />

Chinese Hamster Ovary<br />

AA8 cells in AMEM +<br />

10% FBS<br />

Pb chromate Apoptosis (0.4–2 µg/cm 2 <strong>for</strong> 24 h) Primary Human Small<br />

<strong>Air</strong>way Cells in Clonetics<br />

growth medium<br />

Pb chromate Growth Curve (0.5–5 µg/cm 2 24 h) WTHBF-6—human lung<br />

cells with hTERT in<br />

DMEM/F12 + 10% CCS<br />

Pb glutamate Growth Curve<br />

(250–1,000 µM <strong>for</strong> 24 h)<br />

Pb glutamate Mitotic Index<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Growth Curve<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

Cell cycle Analysis<br />

(250–2,000 µM <strong>for</strong> 24 h)<br />

WTHBF-6—human lung<br />

cells with hTERT in<br />

DMEM/F12 + 10% CCS<br />

WTHBF-6—human lung<br />

cells with hTERT in<br />

DMEM/F12 + 10% CCS<br />

None Pb acetate did not induce apoptosis.<br />

Pb acetate increased the expression <strong>of</strong> TNF-alpha in a dosedependent<br />

manner.<br />

TNF-alpha was not involved in Pb-induced apoptosis.<br />

None Pb chloride inhibited cell growth at all concentrations <strong>for</strong><br />

24–48 h.<br />

Pb chloride did not affect gap junction capacity, which is<br />

<strong>of</strong>ten inhibited by tumor promoters.<br />

None Pb oxide inhibited cell growth at all concentrations <strong>for</strong><br />

24 h–7 days.<br />

Pb oxide did not affect gap junction capacity, which is <strong>of</strong>ten<br />

inhibited by tumor promoters.<br />

None Pb sulfate inhibited cell growth at all concentrations <strong>for</strong> 24–<br />

48 h.<br />

Pb sulfate did not affect gap junction capacity, which is<br />

<strong>of</strong>ten inhibited by tumor promoters.<br />

None Pb chromate induced apoptosis.<br />

This study was focused on chromate.<br />

None Pb chromate induced apoptosis in a concentrationdependent<br />

manner.<br />

Cheng et al.<br />

(2002)<br />

Apostoli et al.<br />

(2000)<br />

Apostoli et al.<br />

(2000)<br />

Apostoli et al.<br />

(2000)<br />

Blankenship<br />

et al. (1997)<br />

Singh et al.<br />

(1999)<br />

None Pb chromate inhibited cell growth. Holmes et al.<br />

(2005)<br />

None Pb glutamate had no effect on growth. Wise et al. (2005)<br />

None Pb glutamate induced a concentration-dependent increase in<br />

intracellular Pb ions.<br />

Pb glutamate increased the mitotic index, but either had no<br />

effect or inhibited growth and induced mitotic arrest.<br />

Wise et al. (2005)


AX5-109<br />

Table AX5-6.19 (cont’d). Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis Human and Animal Cell Culture Studies<br />

Compound<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb nitrate Mitotic Index<br />

(3–30 µM <strong>for</strong> 2h +16 h recovery)<br />

Pb nitrate Mitotic Index<br />

(0.05–1 µM <strong>for</strong> 3–12 h)<br />

Cell Type and<br />

Culture Medium Co-exposure Effects Reference<br />

CHO cells in EMEM +<br />

10% FBS<br />

CHO AA8 in DMEM<br />

+10% NCS<br />

Pb nitrate Apoptosis (15–240 µM <strong>for</strong> 3 h) Rat Alveolar<br />

Macrophages in DMEM<br />

+ 10% FBS<br />

None Lower concentrations (1 and 3 µM) <strong>of</strong> Pb nitrate<br />

significantly increased the mitotic index. Higher<br />

concentrations (10 and 30 µM) had no effect.<br />

Crown ethers to modify<br />

effect through chelation<br />

and uptake<br />

Abbreviations<br />

G12–CHV79 are derived from V79;<br />

V79 are a Chinese Hamster Lung Cell Line;<br />

hTERT is the catalytic subunit <strong>of</strong> human telomerase<br />

Medium and Components<br />

AMEM—Alpha Minimal Essential Medium;<br />

DMEM—Dulbecco’s Minimal Essential Medium;<br />

DMEM/F12—Dulbecco’s Minimal Essential Medium/Ham’s F12;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

BSA—Bovine Serum Albumin<br />

CCS—Cosmic Calf Serum<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

NCS—Newborn Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

Pb nitrate dramatically reduced the mitotic index at 1 µM<br />

though this was not statistically analyzed. There was no<br />

effect on mitotic index at lower concentrations. Crown<br />

ethers had no modifying effect.<br />

Lin et al. (1994)<br />

Cai and Arenaz<br />

(1998)<br />

None Pb nitrate induced apoptosis in a dose-dependent manner. Shabani and<br />

Rabbani (2000)


AX5-110<br />

Compound<br />

Assay (Concentration and<br />

Exposure Time)<br />

Pb acetate Production <strong>of</strong> reactive oxygen<br />

species (1 mM <strong>for</strong> 180 min)<br />

Glutathione levels<br />

(1 mM <strong>for</strong> 0–180 min)<br />

Pb acetate Catalase Activity<br />

(500–2,000 µM <strong>for</strong> 24 h)<br />

Pb acetate Thiol Levels<br />

(100 µM <strong>for</strong> 30 min–4 h)<br />

Pb chloride Oxidative Metabolism<br />

(0.1–100 µM <strong>for</strong> 20 h)<br />

Phagocytosis (0.1–100 µM <strong>for</strong><br />

20 h)<br />

Pb chloride Oxidative Enzyme Levels<br />

(0.1–1 µM <strong>for</strong> 1 h)<br />

Table AX5-6.20. Genotoxic/Carcinogenic Effects <strong>of</strong> <strong>Lead</strong>—Mitogenesis Other<br />

Cell Type and<br />

Culture Medium Co-exposure Effects Reference<br />

SH-SY5Y—Human<br />

neuroblastoma cells in<br />

DMEM + 7% FCS<br />

Human Foreskin<br />

Fibroblasts (Chinese) in<br />

DMEM +10% FCS<br />

HeLa in HEPES/glucose<br />

buffer<br />

Macrophages from NMRI<br />

mice in EMEM (serum<br />

not given)<br />

AS52-CHO-gpt, lack hprt<br />

in HBSS followed by<br />

Ham’s F12 + 5% FBS<br />

Glutamate (1 mM)<br />

or PKC inhibitor<br />

(1 µM)<br />

3-aminotriazole<br />

(3-AT) (80 mM to<br />

inhibit catalase)<br />

Buthionine<br />

sulfoximine<br />

(BSO) to deplete<br />

cells <strong>of</strong> thiols<br />

Zymosan and<br />

latex particles as<br />

substrates <strong>for</strong><br />

phagocytosis<br />

Allopurinol<br />

(50 µM) to inhibit<br />

xanthine oxidase<br />

Abbreviations<br />

AS52 are derived from CHO;<br />

CHO are a Chinese Hamster Ovary Cell Line;<br />

Medium and Components<br />

DMEM—Dulbecco’s Minimal Essential Medium;<br />

EMEM—Eagle’s Minimal Essential Medium;<br />

HBSS—Hank’s Balanced Salt Solution<br />

FBS—Fetal Bovine Serum<br />

FCS—Fetal Calf Serum<br />

Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.<br />

Pb acetate alone did not produce reactive oxygen species. Glutamate<br />

alone did.<br />

Pb acetate plus glutamate increase glutamate induced increases in<br />

reactive oxygen species.<br />

Pb acetate alone did not deplete glutathione. Glutamate alone did.<br />

Pb acetate plus glutamate decreased glumate-induced decrease in<br />

glutathione.<br />

Naarala et al.<br />

(1995)<br />

Pb acetate had no effect on catalase activity. Hwua and<br />

Yang (1998)<br />

Pb acetate only lowered thiols marginally Snyder and<br />

Lachmann<br />

(1989)<br />

Pb inhibited oxidative metabolism.<br />

Pb inhibited phagocytosis, but only significantly at the highest dose.<br />

Pb chloride at low concentrations produced H2O2 at 1 h and not at<br />

24 h. Pb chloride at high concentrations produced no change at 1 h<br />

and increased H2O2 at 24 h. Allopurinol inhibited H2O2 <strong>for</strong>mation at<br />

high Pb concentrations.<br />

Pb chloride had no effect on catalase, glutathione peroxidase,<br />

glutathione reductase. Pb chloride inhibited glutathione-Stransferase,<br />

CuZn-superoxide dismutase, and xanthine oxidase.<br />

Hilbertz et al.<br />

(1986)<br />

Ariza et al.<br />

(1998)


ANNEX TABLES AX5-7<br />

AX5-111


AX5-112<br />

Table AX5-7.1. Light Microscopic, Ultrastructural, and Functional Changes<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Khalil-Manesh<br />

et al. (1992a)<br />

Khalil-Manesh<br />

et al. (1992b)<br />

Khalil-Manesh<br />

et al. (1993a)<br />

Sanchez-<br />

Fructuoso et al.<br />

(2002a)<br />

Sanchez-<br />

Fructuoso et al.<br />

(2002b)<br />

Papaioannou et al.<br />

(1998)<br />

Sprague-Dawley<br />

rat<br />

Sprague-Dawley<br />

rat<br />

Sprague-Dawley<br />

rat<br />

0.5% Pb acetate in drinking water<br />

<strong>for</strong> 12 mo<br />

0.5% Pb discontinued after 6 mo<br />

0.01% Pb discontinued after 6 mo<br />

DMSA 0.5% used in 1/2<br />

Max 125.4 µg/dL<br />

Mean 55 µg/dL<br />

Hi Pb @12 mo<br />

Disc 30.4 µg/dL<br />

Disc + DMSA 19.1 µg/dL<br />

Ctrl 3.1 µg/dL<br />

Lo Pb@12mo<br />

Disc 6.9 µg/dL<br />

DMSA5.5 µg/dL<br />

0.01% Pb acetate <strong>for</strong> 12 mo Max 29.4 µg/dL<br />

Range 9–34 µg/dL<br />

Wistar rat 500 ppm (0.05%) Pb acetate <strong>for</strong><br />

2 mo, then EDTA<br />

Wistar rat 500 ppm (0.05%) Pb acetate <strong>for</strong><br />

2 mo, then EDTA<br />

Dogs 12 mg Pb acetate i.p. H 10<br />

Max 52.9 µg/dL<br />

Day 90: 33.2<br />

Day 137: 22.8<br />

Ctrl: 5.90 µg/dL<br />

Max 52.9 µg/dL<br />

Day 90: 33.2<br />

Day 137: 22.8<br />

Ctrl: 5.90 µg/dL<br />

—<br />

Hyperfiltration at 3 mo. Decreased filtration at 12 mo.<br />

NAG and GST elevated.<br />

Nuclear inclusion bodies at all times.<br />

Tubulointerstitial scarring from 6 mo.<br />

No arterial or arteriolar pathology.<br />

High Pb:<br />

Nuclear inclusion bodies prominent.<br />

Tubulointerstitial disease severe but less than 12 mo<br />

continuous DMSA caused reduction in nuclear inclusion<br />

bodies and tubuloint decrease, and an increase in GFR.<br />

Low Pb:<br />

Neg pathology and increase in GFR with DMSA<br />

GFR increased at 1 and 3 mo.<br />

NAG increased but GST normal.<br />

Pathology neg except at 12 mo—mild tubular atrophy and<br />

interstitial fibrosis seen.<br />

Rats given Pb to day 90, then treated with EDTA or untreated<br />

to day 137.<br />

Marked decrease in kidney, liver, and brain Pb with EDTA but<br />

no change in femur Pb<br />

Hypertrophy and vacuolization <strong>of</strong> medium and small arteries,<br />

mucoid edema and muscular hypertrophy <strong>of</strong> arterioles, include<br />

bodies and fibrosis.<br />

EDTA slowed progression.<br />

Pb includes bodies intracytoplasmically in mesothelial and<br />

giant cells <strong>of</strong> peritoneum and in interstitial connective tissue<br />

cells <strong>of</strong> kidney. None in prox tubules <strong>of</strong> kidney.


AX5-113<br />

Table AX5-7.1 (cont’d). Light Microscopic, Ultrastructural, and Functional Changes<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Vyskocil et al.<br />

(1989)<br />

Vyskocil et al.<br />

(1995)<br />

Vyskocil and<br />

Cizkova (1996)<br />

Sanchez et al.<br />

(2001)<br />

Herak-<br />

Kramberger et al.<br />

(2001)<br />

Fujiwara et al.<br />

(1995),<br />

Kaji et al. (1995b)<br />

Wistar rat 0.5%, 1%, and 2% Pb acetate <strong>for</strong><br />

2–3 mo<br />

0.5%–105 µg/dL<br />

1%–196 µg/dL<br />

2%–320 µg/dL<br />

Wistar rat 1% or 0.1% Pb acetate <strong>for</strong> 2–4 mo 1%–173 µg/dL<br />

0.1%–37.6 µg/dL<br />

Wistar rats Unleaded petrol vapor (4mg/m 3 )<br />

8 hrs/day <strong>for</strong> 60 days<br />

Sprague-Dawley<br />

rat<br />

Rat brush border<br />

membranes<br />

Bovine cultured<br />

vascular smooth<br />

muscle and<br />

endothelial cells<br />

0.06% Pb acetate <strong>for</strong> 4 mo 13.9 µg/dL vs.


AX5-114<br />

Table AX5-7.2. <strong>Lead</strong> and Free Radicals<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Pereira et al.<br />

(1992)<br />

Somashekaraiah<br />

et al. (1992)<br />

Bondy and Guo<br />

(1996)<br />

Blazka et al.<br />

(1994)<br />

Quinn and Harris<br />

(1995)<br />

Rats ALA-treated (40 mg/kg every<br />

2 days <strong>for</strong> 15 days)<br />

Chick embryos 1.25 and 2.5 momol/kg <strong>of</strong> Pb acetate<br />

Sprague-Dawley<br />

rat cerebral<br />

synaptosomes<br />

Mouse brain<br />

microvascular<br />

endothelial cell<br />

culture<br />

Rat cerebellum<br />

homogenates<br />

0.5 mM Pb acetate<br />

10, 100, and 1,000 nM Pb acetate<br />

17–80 nM Pb nitrate<br />

Ercal et al. (1996) C57BL/6 mice 1300 ppm Pb acetate <strong>for</strong> 5 wks,<br />

Nac, 5.5 mmol/kg, or DMSA,<br />

1 mmol/kg, given in 6th week.<br />

Vaziri and coworkers<br />

(1997–<br />

2004)<br />

Farmand et al.<br />

(2005)<br />

Gurer et al.<br />

(1999)<br />

Sprague-Dawley<br />

rats<br />

Sprague-Dawley<br />

rats<br />

—<br />

—<br />

—<br />

—<br />

—<br />

36.5 µg/dL in Pb-treated;<br />

13.7 µg/dL in Pb +<br />

DMSA-treated<br />

Fatigued earlier than controls.<br />

Increase <strong>of</strong> CuZn SOD in brain, muscle and liver.<br />

See Section 5.5 <strong>for</strong> details Variable See Section 5.5 <strong>for</strong> details.<br />

100 ppm Pb acetate <strong>for</strong> 3 mo<br />

Fischer 344 rats 1100 ppm Pb acetate <strong>for</strong> 5 wks,<br />

Captopril <strong>for</strong> 6th wk<br />

—<br />

24.6µg/dL in Pb-treated.<br />

23.8 µg/dL in Pb +<br />

Captopril-treated<br />

Lipoperoxides maximal at 9 hrs and returned to normal at<br />

72 hrs.<br />

GSH depleted. GST, SOD and catalase increased in liver,<br />

brain and heart at 72 hrs.<br />

Generation <strong>of</strong> ROS not increased by Pb alone but increased<br />

when 50 µM iron sulfate added.<br />

Constitutive production <strong>of</strong> nitrite, but not inducible, decreased<br />

by Pb. Extracellular calcium abolishes this effect.<br />

Constitutive NOS activity inhibited 50% by 17 nM Pb and<br />

100% by 80 nM Pb. Reversed by increasing Ca concentration.<br />

Liver and brain GSH depleted by Pb and MDA increased.<br />

Both were restored by either DMSA or NAC. However,<br />

DMSA reduced blood, liver, and brain Pb levels while NAC<br />

did not.<br />

CuZnSOD activity increased in kidney. CuZnSOD activity<br />

increased in aorta whereas protein abundance unchanged.<br />

Guanylate cyclase protein abundance in aorta decreased.<br />

MDA in liver, brain, and kidney increased by Pb. GSH<br />

decreased. Captopril reversed these findings.


AX5-115<br />

Table AX5-7.2 (cont’d). <strong>Lead</strong> and Free Radicals<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Acharya and<br />

Acharya (1997)<br />

Upasani et al.<br />

(2001)<br />

Pande et al.<br />

(2001)<br />

Pande and Flora<br />

(2002)<br />

Swiss mice 200 mg/kg Pb acetate i.p. H 1<br />

Rats 100 ppm Pb acetate <strong>for</strong> 30 days,<br />

Groups given vit C, vit E, or algae —<br />

Wistar rats Pb nitrate 50 mg/kg i.p. H 5<br />

Pb + DMSA,MiADMSA,NAC,<br />

DMSA + NAC,DMSA +<br />

MiADMSA<br />

Wistar rats 2000 ppm Pb acetate H 4 wks,<br />

DMSA,MiADMSA, DMSA +<br />

LA,MiADMSA + LA H 5 days<br />

Flora et al. (2003) Wistar rats 1000 ppm Pb acetate H 3 mo,<br />

DMSA or MiADMSA + vit C or<br />

vit E H 5 days<br />

Saxena and Flora<br />

(2004)<br />

Tandon et al.<br />

(2002)<br />

Wistar rats 2000 ppm Pb acetate H 6 wks,<br />

CaNa 2EDTA + DMPS or<br />

MiADMSA H 5 days<br />

Rats 2000 ppm Pb acetate H 9 wks,<br />

DMSA, MiADMSA, or NAC or<br />

combo H 6 days<br />

—<br />

—<br />

—<br />

13.3 µg/dL<br />

Pb Rx<br />

3 µg/dL DMSA Rx<br />


AX5-116<br />

Table AX5-7.2 (cont’d). <strong>Lead</strong> and Free Radicals<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Sivaprasad et al.<br />

(2002)<br />

Senapati et al.<br />

(2000)<br />

Wistar rats 2000 ppm Pb acetate H 5 wks<br />

LA and DMSA during 6th week.<br />

Rats 1% sol <strong>of</strong> 5 mg/kg<br />

Pb acetate H 43 days<br />

Thiamine 25 mg/kg<br />

Patra et al. (2001) IVRI 2CQ rats 1 mg/kg Pb acetate <strong>for</strong> 4 wks<br />

Vit E, vit C or methionine in 5th wk.<br />

Vit E + EDTA.<br />

McGowan and<br />

Donaldson (1987)<br />

Chicks 2000 ppm Pb acetate H 3 wks<br />

—<br />

—<br />

6.8 µg/dL Pb-Rx<br />

6.3 µg/dL<br />

Pb, vit E +EDTA<br />

—<br />

Pb caused red in kidney GGT and NAG, decline in GSH,<br />

catalase, SOD, GPx and Glut reductase, and increased MDA.<br />

Lipoic acid<br />

+DMSA restored these changes.<br />

Thiamine reduced Pb content and MDA levels <strong>of</strong> both liver<br />

and kidney and improved pathology.<br />

Pb in liver, kidney and brain reduced by vit E + EDTA<br />

treatment. MDA increased by Pb in all 3 organs but decreased<br />

by vit E + EDTA.<br />

GSH, non-protein SH, lysine and methionine increased in liver<br />

and non-prot SH, glycine, cysteine and cystathionine in<br />

kidney. Cysteine reduced in plasma.


AX5-117<br />

Table AX5-7.3. Chelation with DMSA<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Cory-Slechta<br />

(1988)<br />

Pappas et al.<br />

(1995)<br />

Smith and Flegal<br />

(1992)<br />

Varnai et al.<br />

(2001)<br />

Rats 50 ppm Pb acetate <strong>for</strong> 3–4 mo 20 µg/dL-Pb<br />

Sprague-Dawley<br />

rats<br />

Wistar rats<br />

Wistar rats<br />

(suckling)<br />

550–1100 ppm Pb acetate <strong>for</strong><br />

35 days<br />

206 Pb 210 ng/mL <strong>for</strong> 1.5 days<br />

DMSA 20 mg/kg i.p.<br />

2 mg/kg/d <strong>for</strong> 8 days<br />

DMSA 0.5 mmol/kg 6x/d on d1-3<br />

and 6–8<br />

1 µg/dL-Pb+25 mg/kg<br />

DMSA<br />

52 µg/dL @ 550 ppm Pb<br />

65 µg/dL @ 1100 ppm Pb<br />

5.1 ng/g-ctrl<br />

3.0 ng/g-DMSA<br />

—<br />

DMSA 25–50 mg/kg i.p. <strong>for</strong> 1–5 days mobilized Pb from<br />

blood, brain, kidney and liver, but not femur.<br />

DMSA @16–240 mg/kg/d p.o. <strong>for</strong> 21 days given with and<br />

without concurrent Pb exposure. Rats showed dose-related<br />

reduction in Pb content <strong>of</strong> blood, brain, femur, kidney, and<br />

liver with or without concur Pb.<br />

Rats on low Pb diet given DMSA decreased s<strong>of</strong>t tissue but not<br />

skeletal Pb. Pb redistributed to skeleton.<br />

DMSA reduced Pb concentration in carcass, liver, kidneys, and<br />

brain by ~50%.


AX5-118<br />

Table AX5-7.4. Effect <strong>of</strong> Chelator Combinations<br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Flora et al.<br />

(2004)<br />

Jones et al.<br />

(1994)<br />

Kostial et al.<br />

(1999)<br />

Flora et al.<br />

(2004)<br />

Sivaprasad et al.<br />

(2004)<br />

Malvezzi et al.<br />

(2001)<br />

Tandon et al.<br />

(1997)<br />

Wistar rats 1000 ppm Pb acetate <strong>for</strong> 4 mo 46 µg/dL-Pb<br />

Mice 10 i.p. injections <strong>of</strong> Pb acetate,<br />

5.0 mg/kg<br />

Wistar rats<br />

(suckling)<br />

5 mg Pb/kg i.p. H 1<br />

Chel agents days 2 and 3<br />

Wistar rats 1000 ppm Pb acetate H 2 mo<br />

Wistar rats 2000 ppm Pb acetate H 5 wks<br />

Wistar rats 750 ppm Pb acetate H 70 days<br />

DMSA, arginine, DMSA + arg or<br />

H2O H 30 days<br />

Rats 1000 ppm Pb acetate <strong>for</strong> 7 wks.<br />

Dithiocarbamate H 4 days<br />

12.8 µg/dL-combined Rx<br />

—<br />

—<br />

—<br />

—<br />

67.8 µg/dL to 11.2 µg/dL<br />

in H 2O Rx’ed to 6.1<br />

µg/dL in DMSA + arg<br />

105.3 µg/dL in Pb<br />

86 µg/dL in<br />

dithiocarbamate.<br />

5 days Rx with DMSA. CaNa 2EDTA, or DMSA +<br />

CaNa2EDTA. Comb Rx resulted in increased ALAD and<br />

decreased Pb in blood, liver, brain, and femur.<br />

Mice Rx’ed with DMSA, CaNa 2EDTA, ZnNa 2EDTA, or<br />

ZnNa 3DTPA 1.0 mmol/kg/d 4–8 days. CaNa 2EDTA most<br />

effective in removing brain Pb; DMSA in removing kidney<br />

and bone Pb.<br />

EDTA, DMSA, racemic DMSA, EDTA + DMSA, EDTA +<br />

rac DMSA given. EDTA reduced Zn in carcass and liver; rac<br />

DMSA reduced Zn in kidneys. DMSA reduced Pb w/o<br />

affecting Zn.<br />

DMSA, taurine or DMSA + taurine given <strong>for</strong> 5 days. Both<br />

taurine and DMSA restored GSH. Comb <strong>of</strong> DMSA + taurine<br />

increased RBC SOD and decreased TBARS, while most<br />

effectively depleting blood, liver, and brain Pb.<br />

DMSA, lipoic acid or combination given during 6th week.<br />

Renal enzymes, kidney Pb and renal ALAD restored by<br />

combined Rx.<br />

Pb increased BP and Pb levels in blood, liver, femur, kidney,<br />

and aorta. DMSA + L-arginine most effective in lowering BP<br />

and mobilizing Pb from tissues.<br />

Two dithiocarbamates were compared: N-benzyl-D-glucamine<br />

and N-(4-methoxybenzyl)-D-glucamine. They were only<br />

partially effective in restoring ALAD, reducing liver and<br />

kidney, but not brain Pb. They depleted Zn, Cu, and Ca.


AX5-119<br />

Table AX5-7.5. Effect <strong>of</strong> Other Metals on <strong>Lead</strong><br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Maldonado-Vega<br />

et al. (1996)<br />

Wistar rats<br />

(pregnant and<br />

nonpregnant)<br />

Olivi et al. (2002) MDCK canine<br />

kidney cells<br />

Bogden et al.<br />

(1991)<br />

Skoczyńska et al.<br />

(1994)<br />

Othman and<br />

El-Missiry (1998)<br />

Tandon et al.<br />

(1992)<br />

100 ppm Pb acetate <strong>for</strong> 144–<br />

158 days<br />

1 µM<br />

Wistar rats 0,1,100 ppm Pb <strong>for</strong> 31 wks<br />

0.2% or 4.0% Ca diet<br />

Buffalo rats Pb 70 mg/kg 2x/wk <strong>for</strong> 7 wks Cd<br />

20 mg/kg 1x/wk <strong>for</strong> 7 wks.<br />

All intragastric.<br />

Albino rats Pb acetate 100 momol/kg I.M. H 1<br />

Se 10 momol/kg I.M. 2 hrs be<strong>for</strong>e<br />

Pb<br />

Albino rats Pb acetate 10 mg/kg/d p.o. H 6 wks.<br />

EDTA or DTPA given <strong>for</strong> 5 days w/<br />

or w/o Se<br />

Flora et al. (1989) Albino rats Pb acetate 10 mg/kg/d p.o. H 6 wks<br />

Thiamine, Zn or thiamine + Zn H 6<br />

wks<br />

Flora et al. (1994) Wistar albino rats Pb acetate 10 mg/kg/d H 56 days<br />

p.o. EDTA or EDTA + Zn H 5 days<br />

p.o.<br />

5.2 (ctrl) to 27.3 µg/dL in<br />

Pb-exposed<br />

8 (non-preg) to 17 µg/dL<br />

in rats exposed only<br />

during lactation<br />

—<br />

1.9 to 39.1 µg/dL on low<br />

Ca diet and 2.0 to 53.3<br />

µg/dL on high Ca diet<br />

5.1 to 29.6 µg/dL in Pbexposed.<br />

37.4 µg/dL in<br />

Pb + Cd<br />

—<br />

17 to 138 µg/dL after Pb<br />

58 µg/dL after EDTA.<br />

50 µg/dL after EDTA + Se<br />

6.2 to 120.9 µg/dL after<br />

Pb<br />

44.1 µg/dL after thiamine<br />

+ Zn<br />

4.6 to 43.0 µg/dL in Pb.<br />

22.5 µg/dL in EDTA<br />

16.5 µg/dL in EDTA +<br />

Zn.<br />

Pb administered to period be<strong>for</strong>e lactation (144 days) or to<br />

mid-lactation (158 days).Pb in blood, kidney, liver, and bone<br />

increased.<br />

ALAD decreased and FEP incr. Lactation increased.<br />

Blood Pb from 24.7 to 31.2 µg/dL and decreased bone Pb from<br />

83.4 to 65.2 nmol/g.<br />

In response to agonists ADP or bradykinin levels <strong>of</strong><br />

intracellular Ca increased 3-fold and 2-fold. Pb inhibited the<br />

response.<br />

At 100 ppm Pb high Ca diet produced higher BP and more<br />

renal cancers than low Ca diet and higher levels <strong>of</strong> Pb in brain,<br />

liver, bone, heart, and testis but lower levels in kidney. Serum<br />

Ca on high Ca diet was 13.2 mg/dL.<br />

Simultaneous Pb and Cd administration increased blood Pb but<br />

decreased Pb in liver and kidneys as compared to Pb<br />

administration alone.<br />

Sodium selenite (Se is a well-known anti-oxidant) prevented<br />

lipid peroxidation (TBARS) and reduction in GSH caused by<br />

Pb. SOD and glut reductase also normalized.<br />

Selenium had no additional benefit over chelators except <strong>for</strong><br />

higher ALAD and lower ZPP in blood, lower Pb in liver and<br />

kidney.<br />

Thiamine given as 25 mg/kg/d and Zn sulfate as 25 mg/kg/d.<br />

ALAD restored by combined Rx. Liver and kidney Pb<br />

affected to a minor degree but brain Pb not affected.<br />

CaNa2 EDTA given as 0.3 mmol/kg/d i.p. and Zn sulfate as 10<br />

or 50 mg/kg/d. ALAD partially restored after EDTA + Zn but<br />

not after EDTA. EDTA reduced Pb in bone, kidney, and liver<br />

but not in brain. Zn conc increased in blood, kidney, and brain<br />

by 50 mg Zn dosage.


AX5-120<br />

Table AX5-7.5 (cont’d). Effect <strong>of</strong> Other Metals on <strong>Lead</strong><br />

Author Animal Species <strong>Lead</strong> Dosage Blood <strong>Lead</strong> Findings<br />

Satija and Vij<br />

(1995)<br />

Munoz et al.<br />

(1993)<br />

Tandon et al.<br />

(1997)<br />

Hashmi et al.<br />

(1989)<br />

Tandon et al.<br />

(1993)<br />

Crowe and<br />

Morgan (1996)<br />

Singh et al.<br />

(1991)<br />

Shakoor et al.<br />

(2000)<br />

Albino rats Pb acetate 20 mg/kg/d i.p. H 3 days<br />

Zn acetate 5 mg/kg/d i.p. H 3 days —<br />

Wistar rats Pb acetate 60 ppm H 90 days,<br />

Zn or methionine given<br />

simultaneously<br />

Albino rats Pb acetate 10 mg/kg/d H 8 wks p.o.<br />

Ethanol, Zn and lysine H 8 wks<br />

Rats Pb acetate 1000 ppm H 6 wks<br />

Fe-deficient or norm diet<br />

Rats Pb acetate 400 momol/kg i.p. H 1<br />

Fe deficient and Fe-sufficient diets<br />

H 6 wk<br />

Wistar rat pups Pb acetate 2000 ppm H 15, 21, and<br />

63 days<br />

Fe def and Fe suff diets<br />

Pregnant female<br />

albino rats<br />

Pb acetate 250–2000 ppm from<br />

15–20 days <strong>of</strong> gestation.<br />


ANNEX TABLES AX5-8<br />

AX5-121


AX5-122<br />

Table AX5-8.1. Bone Growth in <strong>Lead</strong>-exposed Animals<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

41.7 mg Pb/l<br />

83.3 mg Pb/l<br />

166.6 mg Pb/l<br />

12 to 16 wks<br />

Drinking water<br />

Pb aerosol<br />

77, 249, or 1546 µg/m 3<br />

<strong>for</strong> 50 to 70 days<br />

Inhalation<br />

Pb acetate<br />

250 ppm or 1000 ppm<br />

7 wks to females prior<br />

to mating, continuing<br />

through gestation and<br />

lactation<br />

Drinking water<br />

Rat Pb level in bone <strong>of</strong> control animals<br />

Wk 0 = 1.3 ± 0.83 µg Pb/g; Wk 4 = 1.2 ± 0.99 µg Pb/g;<br />

Wk 8 = 1.3 ± 1.08 µg Pb/g; Wk 12 = 0.8 ± 0.13 µg Pb/g;<br />

Wk 16 = 1.3 ± 0.95 µg Pb/g<br />

Pb level in bone <strong>of</strong> animals receiving 41.7 mg Pb/l<br />

Wk 0 = 1.0 ± 0.50 µg Pb/g; Wk 4 = 5.9* ± 1.76 µg Pb/g;<br />

Wk 8 = 2.9* ± 1.15 µg Pb/g; Wk 12 = 6.2* ± 1.01 µg Pb/g;<br />

Wk 16 = 6.0* ± 0.75 µg Pb/g<br />

Pb level in bone <strong>of</strong> animals receiving 83.3 mg Pb/l<br />

Wk 0 = 2.0 ± 0.97 µg Pb/g; Wk 4 = 11.7* ± 3.56 µg Pb/g;<br />

Wk 8 = 8.8* ± 3.37 µg Pb/g; Wk 12 = 14.3* ± 4.29 µg Pb/g<br />

Pb level in bone <strong>of</strong> animals receiving 166.6 mg Pb/l<br />

Wk 0 = 0.9 ± 0.23 µg Pb/g; Wk 4 = 17.0* ± 3.89 µg Pb/g;<br />

Wk 8 = 35.7* ± 3.64 µg Pb/g; Wk 12 = 21.7* ± 5.11 µg Pb/g;<br />

*significantly higher than control animals at corresponding time point<br />

Rat 16.9 ± 6.6 µg Pb/g bone taken up in animals exposed to 77 µg/m 3 <strong>for</strong><br />

70 days versus 0.2 ± 0.2 µg Pb/g in control animals;<br />

15.9 ± 4.3 µg Pb/g bone in rats exposed to 249 µg/m 3 <strong>for</strong> 50 days;<br />

158 ± 21 µg Pb/g bone in rats exposed to 1546 µg/m 3 <strong>for</strong> 50 days<br />

Rat Offspring body weight was depressed relative to controls during<br />

suckling (Day 11) and after weaning (Day 24) in high dose and<br />

continuously Pb-exposed groups.<br />

Continuous Pb exposure caused a greater decrease in <strong>of</strong>fspring body<br />

weight than Pb exposure only prior to or after parturition.<br />

Decreased tail length growth suggested possible effects <strong>of</strong> Pb on tail<br />

vertebral bone growth.<br />

Not given Hać and Krechniak<br />

(1996)<br />

Control: 2.6 µg/dL<br />

77 µg/m 3 : 11.5 µg/dL<br />

249 µg/m 3 : 24.1 µg/dL<br />

1546 µg/m 3 : 61.2 µg/dL<br />

Dams prior to mating:<br />

Control = 2.7 ± 0.6 µg/dL<br />

250 ppm = 39.9 ± 3.5 µg/dL<br />

1000 ppm = 73.5 ± 9.3 µg/dL<br />

Grobler et al. (1991)<br />

Hamilton and<br />

O’Flaherty (1994)


AX5-123<br />

Table AX5-8.1 (cont’d). Bone Growth in <strong>Lead</strong>-exposed Animals<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

Hi Pb animals 5000<br />

ppm <strong>for</strong> 6 mo, reduced<br />

to 1000 ppm;<br />

Lo Pb animals 100 ppm<br />

Drinking Water<br />

Pb acetate<br />

17 mg per kg <strong>of</strong> feed<br />

50 days<br />

In diet<br />

Pb acetate<br />

17 mg per kg <strong>of</strong> feed<br />

50 days<br />

In diet<br />

Rat In male rats exposed to 100 ppm Pb in drinking water and a low<br />

calcium diet <strong>for</strong> up to one yr, bone density was significantly decreased<br />

after 12 mo, while rats exposed to 5000 ppm Pb had significantly<br />

decreased bone density after 3 mo. Pb content <strong>of</strong> femurs was<br />

significantly elevated over the content <strong>of</strong> control rats at all time points<br />

(1, 3, 6, 9, 12 mo). Trabecular bone from the low dose animals was<br />

significantly decreased from 3 mo <strong>for</strong>ward.<br />

Rat No differences in the length <strong>of</strong> the femurs, but the mean length <strong>of</strong> the<br />

5th lumbar vertebra was significantly decreased. The mean length <strong>of</strong><br />

the femur growth plate cartilage was also significantly decreased in Pbexposed<br />

animals.<br />

Rat No differences in the length <strong>of</strong> the femurs, but the mean length <strong>of</strong> the<br />

5th lumbar vertebra was significantly decreased. The mean length <strong>of</strong><br />

the femur growth plate cartilage was also significantly decreased in Pbexposed<br />

animals.<br />

Low Pb (µg%):<br />

1 mo<br />

Control = 2 ± 1; Exp = 19 ± 10*<br />

3 mo<br />

Control = 2 ± 1; Exp = 29 ± 4*<br />

6 mo<br />

Control = 3 ± 1; Exp = 18 ± 2*<br />

9 mo<br />

Control = 1 ± 1; Exp = 17 ± 3*<br />

12 mo<br />

Control = 3 ± 1; Exp = 21 ± 3*<br />

Hi Pb (µg%):<br />

1 mo<br />

Control = 3 ± 1; Exp = 45 ± 13*<br />

3 mo<br />

Control = 3 ± 1; Exp = 90 ± 15*<br />

6 mo<br />

Control = 4 ± 1; Exp = 126 ± 10*<br />

9 mo<br />

Control = 4 ± 1; Exp = 80 ± 39*<br />

12 mo<br />

Control = 3 ± 1; Exp = 59 ± 18*<br />

*p < 0.001<br />

Gruber et al. (1997)<br />

Not given González-Riola et al.<br />

(1997)<br />

Not given Escribano et al. (1997)


AX5-124<br />

Table AX5-8.1 (cont’d). Bone Growth in <strong>Lead</strong>-exposed Animals<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

0.6%<br />

GD 5 to Adulthood<br />

(various)<br />

In drinking water<br />

Pb acetate<br />

0.05% to 0.45%<br />

GD 5 through sacrifice<br />

<strong>of</strong> pups at 21, 35, 55,<br />

and 85 days<br />

In drinking water<br />

Pb nitrate<br />

0.02% (125 ppm)<br />

GD5 to 1 day be<strong>for</strong>e<br />

sacrifice<br />

In drinking water<br />

Rat Early bone growth was significantly depressed in a dose-dependent<br />

fashion in pups <strong>of</strong> Pb-exposed pups, with growth suppression in male<br />

<strong>of</strong>fspring considerably greater than females. Significant decreases in<br />

plasma insulin-like growth factor and plasma sex steroids and<br />

increased pituitary growth hormone were also observed.<br />

Groups:<br />

DDW = Dams and pups received distilled deionized water entire study<br />

Ac/Ac = Dams and pups received acetic acid solution entire study<br />

Preg = Dams received 0.6% Pb water from GD 5 to parturition<br />

Lact = Dams received 0.6% Pb water during lactation only<br />

P + L = Dams received 0.6% Pb water from GD 5 through lactation<br />

Postnatal = Dams and pups received 0.6% Pb water from parturition<br />

through adulthood<br />

Pb/Pb = Dams and pups received 0.6% Pb water from GD 5 through<br />

adulthood<br />

Rat Early bone growth was significantly depressed in a dose-dependent<br />

fashion in pups <strong>of</strong> all Pb-exposed groups, with growth suppression in<br />

male <strong>of</strong>fspring considerably greater than females. Significant<br />

decreases in plasma insulin-like growth factor and plasma sex steroids<br />

and increased pituitary growth hormone were also observed.<br />

Between age 57 and 85 days growth rates were similar in control and<br />

Pb-exposed pups, suggesting exposure at critical growth periods such<br />

as puberty and gender may account <strong>for</strong> differences in growth reported<br />

by various investigators.<br />

Rat Exposure to 0.02% Pb nitrate (125 ppm Pb) did not significantly affect<br />

growth, though males weighed significantly less than females.<br />

Whole blood Pb (µg/dL) in<br />

male/female <strong>of</strong>fspring at age<br />

Day 85:<br />

DDW = 5.5 ± 2.0/6.8 ± 1.5;<br />

Ac/Ac = 1.9 ± 0.2/1.4 ± 0.3;<br />

Preg = 9.1 ± 0.7*/11.6 ± 4.6*;<br />

Lact = 3.3 ± 0.4/3.4 ± 0.8;<br />

P + L = 16.1 ± 2.3*/10.4 ± 1.8*;<br />

Postnatal = 226.0 ± 29.0*/292.0 ±<br />

53.0*;<br />

Pb/Pb = 316.0 ±53.0*/264.0 ±<br />

21.0*<br />

*p < 0.05 compared to Ac/Ac<br />

group.<br />

Offspring:<br />

0.05% Pb = 49 ± 6 µg/dL; 0.15%<br />

Pb = 126 ± 16 µg/dL; 0.45% Pb =<br />

263 ± 28 µg/dL<br />

Rat Pups<br />

5 days old: 43.3 ± 2.7 µg/dL<br />

49 days old: 18.9 ± 0.7 µg/dL<br />

(females: 19.94 ± 0.8 µg/dL;<br />

males: 17.00 ± 1.1 µg/dL)<br />

Ronis et al. (1998a)<br />

Ronis et al. (1998b)<br />

Camoratto et al. (1993)


AX5-125<br />

Table AX5-8.1 (cont’d). Bone Growth in <strong>Lead</strong>-exposed Animals<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

0.15% or 0.45%<br />

GD 4 until Day 55<br />

In drinking water<br />

Pb acetate<br />

1000 ppm<br />

22–26 days<br />

In drinking water<br />

Abbreviations<br />

Mg—milligram<br />

µg—microgram<br />

ppm—parts per million<br />

GD—gestational day<br />

Pb—lead<br />

g—gram<br />

µg%—microgram percent<br />

Rat A dose-dependent decrease in load to failure in tibia from Pb-exposed<br />

(0.15% and 0.45% Pb acetate in drinking water) male pups only.<br />

Hormone treatments (L-dopa, testosterone or dihydrotestosterone in<br />

males, or estradiol in females) failed to attenuate Pb deficits during the<br />

pubertal period. Distraction osteogenesis experiments per<strong>for</strong>med after<br />

stabilization <strong>of</strong> endocrine parameters (at 100 days <strong>of</strong> age) found<br />

decreased new endosteal bone <strong>for</strong>mation and gap x-ray density in the<br />

distraction gaps <strong>of</strong> Pb-exposed animals.<br />

Rat Pb disrupted mineralization during growth in demineralized bone<br />

matrix implanted subcutaneously into male rats. In the matrix that<br />

contained 200 micrograms Pb/g <strong>of</strong> plaque tissue, alkaline phosphatase<br />

activity and cartilage mineralization were absent, though calcium<br />

deposition was enhanced. Separate experiments found enhanced<br />

calcification and decreased alkaline phosphatase activity in rats<br />

implanted with a control (no Pb) matrix and given 1000 ppm Pb in<br />

drinking water <strong>for</strong> 26 days.<br />

l—liter<br />

m 3 - —cubic meter<br />

Exp—experimental group<br />

wk—week<br />

dL—deciliter<br />

%—percent<br />

Offspring:<br />

0.15% Pb = 67–192 µg/dL;<br />

0.45% Pb = 120–388 µg/dL<br />

Blood Pb (µg/dL)<br />

Control:<br />

Implantation Day 0 = 1.3 ± 0.6;<br />

Day 8 = 2.2 ± 0.9; Day 12 = 2.1 ±<br />

0.7.<br />

Pb added to matrix:<br />

Implantation Day 0 = 1.5 ± 0.8;<br />

Day 8 = 5.7 ± 0.8 a,b ; Day 12 = 9.5<br />

± 0.5 a,b .<br />

Pb in drinking water:<br />

Implantation Day 0 = 129.8 ±<br />

6.7 a ; Day 8 = 100.6 ± 6.8 a,b<br />

Day 12 = 96.4 ± 5.3 a,b .<br />

a<br />

Significant (p # 0.05) difference<br />

from control.<br />

b<br />

Significance (p # 0.05)<br />

difference from corresponding<br />

value at implantation (Day 0).<br />

Ronis et al. (2001)<br />

Hamilton and<br />

O’Flaherty (1995)


AX5-126<br />

Table AX5-8.2. Regulation <strong>of</strong> Bone Cell Function in Animals—Systemic Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

30 mg/kg<br />

Single i.v. injection<br />

Pb acetate<br />

0.82%<br />

1 wk<br />

In diet<br />

Pb acetate<br />

0.15% or 0.45%<br />

GD 4 until Day 55<br />

In drinking water<br />

Rat Groups <strong>of</strong> male rats were killed 0.5, 5, 15, and 30 min and 1, 2, 6, and 12 h after the single<br />

Pb injection. Serum calcium and phosphorus levels both initially increased after Pb<br />

injection with serum phosphorus reaching a maximum value (13.5 mg%) after 30 min and<br />

calcium (17 mg%) after 1 h. Calcium and phosphorus levels decreased after 1 h and<br />

returned to baseline levels after 12 h.<br />

Rat<br />

Ingestion <strong>of</strong> 0.82% Pb in male rats fed either a low phosphorus or low calcium diet reduced<br />

plasma levels <strong>of</strong> 1,25-(OH) 2CC, while Pb had no effect in rats fed either a high calcium diet<br />

or a normal phosphorus diet.<br />

Effect <strong>of</strong> Pb on serum 1,25-(OH)2CC levels in rats fed low P or normal P diet<br />

Dietary Phosphorus<br />

0.1%<br />

0.1%<br />

0.1%<br />

0.3%<br />

0.3%<br />

0.3%<br />

Supplement<br />

Control<br />

Cholecalciferol<br />

0.82% Pb+Cholecalciferol<br />

Control<br />

Cholecalciferol<br />

0.82% Pb+Cholecalciferol<br />

Serum 1,25-(OH) 2CC<br />


AX5-127<br />

Table AX5-8.2 (cont’d). Regulation <strong>of</strong> Bone Cell Function in Animals—Systemic Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

PbCl 2<br />

0, 0.2, or 0.8%<br />

1 or 2 wks<br />

In diet<br />

PbCl 2<br />

0, 0.2, or 0.8%<br />

1 or 2 wks<br />

In diet<br />

Pb acetate<br />

1% <strong>for</strong> 10 wks or<br />

0.001–1% <strong>for</strong> 24 wks<br />

In drinking water<br />

Chicks Compared with control animals, Pb exposure significantly increased intestinal calbindin<br />

protein and mRNA levels in addition to plasma 1,25-dihydroxyvitamin D concentration.<br />

The effect was present after 1 wk <strong>of</strong> exposure and continued through the second week. In<br />

calcium-deficient animals increased plasma 1,25-dihydroxyvitamin D and calbindin protein<br />

and mRNA were significantly (p < 0.05) inhibited by Pb exposure in a dose dependent<br />

fashion over the 2 wk experimental period.<br />

Chicks Dose dependent increases in serum 1,25-(OH2)D 3 levels (and Calbindin-D protein and<br />

mRNA) with increasing dietary Pb exposure (0.1% to 0.8%) in experiments per<strong>for</strong>med on<br />

Leghorn cockerel chicks fed an adequate calcium diet.<br />

Rat<br />

Short term administration <strong>of</strong> 1% Pb resulted in significant increases in bone Pb. Total<br />

serum calcium and ionized serum calcium were significantly decreased, as compared to<br />

controls. Circulating levels <strong>of</strong> 1,25-(OH 2)D 3 were also decreased, though the rats were<br />

maintained on a normal calcium diet (0.95%). In the long term study, a dose-dependent<br />

increase in parathyroid weight occurred with increasing exposure to Pb in drinking water.<br />

Short term (10 wks) exposure<br />

Serum Calcium (mM) Ionized Calcium<br />

(mM) 1,25(OH)2D 3 (pM)<br />

Parathyroid Weight (µg/gland)<br />

*p < 0.01<br />

Long term (24 wks) exposure<br />

Pb in water<br />

0%<br />

0.001%<br />

0.01%<br />

0.1%<br />

1.0%<br />

p < 0.01<br />

Controls<br />

2.42 ± 0.03<br />

1.25 ± 0.03<br />

232 ± 18.9<br />

96 ± 34<br />

Normalized Parathyroid<br />

Weight (µg/g body wt)<br />

0.50 ± 0.06<br />

0.72 ± 0.25<br />

0.81 ± 0.28<br />

0.94 ± 0.27<br />

0.81 ± 0.29*<br />

Pb-exposed<br />

2.32 ± 0.02*<br />

1.15 ± 0.03*<br />

177 ± 10.8*<br />

178 ± 25*<br />

1,25(OH) 2D 3 (pM)<br />

241 ± 32<br />

188 ± 27<br />

163 ± 17<br />

206 ± 24<br />

144 ± 33*<br />

None given Fullmer (1995)<br />

None given Fullmer et al.<br />

(1996)<br />

Short term (10 wk)<br />

study:<br />

Control:<br />

< 0.02 µg/l<br />

Pb-exposed:<br />

> 5µg/l<br />

Szabo et al. (1991)


AX5-128<br />

Table AX5-8.2 (cont’d). Regulation <strong>of</strong> Bone Cell Function in Animals—Systemic Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb nitrate<br />

0.02% (125 ppm)<br />

GD5 to 1 day be<strong>for</strong>e<br />

sacrifice<br />

In drinking water<br />

Pb acetate<br />

0.05% to 0.45%<br />

GD 5 through sacrifice<br />

<strong>of</strong> pups at 21, 35, 55,<br />

and 85 days<br />

In drinking water<br />

Abbreviations<br />

mg—milligram<br />

h—hour<br />

1,25-(OH) 2CC—1,25-dihydroxycholecalcigerol<br />

µg—microgram<br />

25-OH D 3—25-hydroxycholecalciferol<br />

PbCl2—lead chloride<br />

1,25-(OH) 2 D 3—vitamin D 3<br />

kg—kilogram<br />

mg%—milligram percent<br />

pg—picogram<br />

Rat Basal release <strong>of</strong> growth hormone from control and Pb-exposed pups at age 49 days was not<br />

significantly different. Growth hormone releasing factor-stimulated release <strong>of</strong> growth<br />

hormone from pituitaries <strong>of</strong> Pb-exposed pups was smaller than the stimulated release <strong>of</strong><br />

growth hormone from pituitaries <strong>of</strong> control animals (75% increase over baseline vs. 171%<br />

increase, respectively), but the difference did not achieve significance (P = 0.08). Growth<br />

hormone content <strong>of</strong> the pituitary glands was also not influenced by Pb exposure.<br />

Rat Pituitary GH content (µg/mg) at postnatal day 55:<br />

Control Male Pups = 56.6 ± 8.0; Female Pups = 85.6 ± 9.3<br />

0.05% Pb Male Pups = 107.2 ± 10.5*; Female Pups = 116.2 ± 9.1<br />

0.15% Pb Male Pups = 96.8 ± 5.0*; Female Pups = 105.1 ± 7.3<br />

0.45% Pb Male Pups = 106.0 ± 9.8*; Female Pups = 157.0 ± 9.9*<br />

*significantly different from control, p < 0.05<br />

GD—gestational day<br />

mM—millimolar<br />

Pb—lead<br />

pM—picomolar<br />

i.v.—intravenous<br />

%—percent<br />

mL—milliliter<br />

dL—deciliter<br />

mRNA—messenger ribonucleic acid<br />

ppm—parts per million<br />

GH—growth hormone<br />

min—minute<br />

Rat Pups<br />

5 days old: 43.3 ±<br />

2.7 µg/dL<br />

49 days old: 18.9<br />

± 0.7 µg/dL<br />

(females: 19.94 ±<br />

0.8 µg/dL; males:<br />

17.00 ± 1.1 µg/dL)<br />

Offspring:<br />

0.05% Pb = 49 ± 6<br />

µg/dL; 0.15% Pb =<br />

126 ± 16 µg/dL;<br />

0.45% Pb = 263 ±<br />

28 µg/dL<br />

Camoratto et al.<br />

(1993)<br />

Ronis et al.<br />

(1998b)


AX5-129<br />

Table AX5-8.3. Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Stable “Pb”<br />

5 mg/mL in drinking<br />

water given during<br />

gestation.<br />

On GD 18, 50 µCi<br />

210 Pb given i.v. to<br />

pregnant dams<br />

210 Pb nitrate<br />

6.5 to 65 µM<br />

5 min to 2 h<br />

In medium<br />

210 Pb nitrate<br />

5 µM<br />

20 hours<br />

In medium<br />

Pb acetate<br />

0 to 50 µM<br />

20 h<br />

In medium<br />

Rat<br />

(fetal bone<br />

organ culture)<br />

Mice<br />

(bone cell<br />

isolation from<br />

calvaria)<br />

Mice<br />

(osteoclastic<br />

bone cell<br />

isolation from<br />

calvaria)<br />

Mice<br />

(osteoclastic<br />

bone cell<br />

isolation from<br />

calvaria)<br />

PTH (3885 IU/mg bone) enhanced cell-mediated release <strong>of</strong> 210 Pb from bone. Release<br />

<strong>of</strong> 210 Pb was accompanied by proportional loss <strong>of</strong> stable Pb and calcium from treated<br />

bones.<br />

Time: Release <strong>of</strong> 210 Pb (EM/CM ratio)<br />

0 min 1.00<br />

10 min 0.82 ± 0.05<br />

2 hr 1.12 ± 0.04<br />

6 hr 1.59 ± 0.08*<br />

24 hr 3.69 ± 0.15*<br />

48 hr 3.75 ± 0.09*<br />

48 hr 0.78 ± 0.14* (in presence <strong>of</strong> 30 mU/mL salmon calcitonin)<br />

*Different from 1.00, p < 0.01.<br />

Uptake <strong>of</strong> 210 Pb by OC cells rapid.<br />

OC cells have greater avidity <strong>for</strong> Pb compared to OB cells.<br />

OC cell uptake <strong>of</strong> Pb almost linear vs. little increase in Pb uptake by OB cells with<br />

increasing Pb concentrations in media.<br />

15–30% release <strong>of</strong> 210 Pb label occurred in OC cells over 2 h time period.<br />

Physiological concentrations <strong>of</strong> PTH resulted in marked increase in 210 Pb and 45 Ca<br />

uptake by OC cells. 210 Pb uptake linear over PTH concentrations <strong>of</strong> 50 to 250 ng/mL).<br />

Media concentrations <strong>of</strong> Pb $26 µM enhanced calcium uptake by cells.<br />

Three readily exchangeable kinetic pools <strong>of</strong> intracellular Pb identified, with the<br />

majority (~78%) associated with the mitochondrial complex.<br />

Cultures were labeled with 45 Ca (25 µCi/mL) <strong>for</strong> 2 or 24 h and kinetic parameters<br />

were examined by analysis <strong>of</strong> 45 Ca washout curves.<br />

In kinetic analysis using dual-label (1–2 µCi/mL 210 Pb and 25 µCi/mL 45 Ca) wash out<br />

curves, the Ca:Pb ratios <strong>of</strong> the rate constants were ~1:1, suggesting similar cellular<br />

metabolism.<br />

Not given/not<br />

applicable<br />

Rosen and Wexler<br />

(1977)<br />

Not applicable Rosen (1983)<br />

Not applicable Pounds and Rosen<br />

(1986)<br />

Not applicable Rosen and Pounds<br />

(1988)


AX5-130<br />

Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate and 210 Pb<br />

label<br />

0–100 µM<br />

20 hr<br />

In medium<br />

Pb acetate<br />

5 or 25 µM<br />

Up to 5 hr<br />

In medium<br />

Pb nitrate<br />

5 µM<br />

20 min<br />

In medium<br />

Pb 2+<br />

5 or 12.5 µM<br />

Up to 100 min<br />

In medium<br />

Mice<br />

(osteoclastic<br />

bone cell<br />

isolation from<br />

calvaria) and<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

(osteoblastic<br />

bone cell<br />

isolation from<br />

calvaria)<br />

Rat<br />

(osteoblastic<br />

bone cell<br />

isolation from<br />

calvaria)<br />

Concentrations as high as 100 µM did not cause toxicity in either cell culture. There<br />

was a slight decrease in growth <strong>of</strong> ROS cells at 5 µM Pb concentration and a 50%<br />

decrease in growth at 25 µM Pb at day 9.<br />

210 Pb washout experiments with both cell cultures indicated similar steady-state Pb<br />

kinetics and intracellular Pb metabolism. Both cell cultures exhibited one large,<br />

slowly exchanging pool <strong>of</strong> Pb, indicative <strong>of</strong> the mitochondrial pool.<br />

Used 19 F NMR in combination with 1,2-bis(2-amino-5-fluorophenoxy)ethane-<br />

N,N,N’,N’-tetraacetic acid (5F-BAPTA) to distinguish and measure concentrations<br />

<strong>of</strong> Pb 2+ and Ca 2+ in aqueous solution.<br />

Basal concentration <strong>of</strong> [Ca 2+ ] i was 128 ± 24 nM. Treatment <strong>of</strong> cells with 5 and 25<br />

µM Pb 2+ produced sustained 50% and 120% increases in [Ca 2+ ] i, respectively, over a<br />

5 hour exposure period.<br />

At a medium concentration <strong>of</strong> 25 µM Pb 2+ a measurable entry <strong>of</strong> Pb 2+ into the cells<br />

([Pb 2+ ] i <strong>of</strong> 29 ± 8 pM) was noted.<br />

Pb (5 µM) linearly raised the emission ratio <strong>of</strong> FURA-2 loaded cells 2-fold within 20<br />

min <strong>of</strong> application, most likely due to increase in [Pb 2+ ] i rather than increase in<br />

[Ca 2+ ] i.<br />

Intracellular calcium increased even in the absence <strong>of</strong> extracellular calcium.<br />

5 or 12.5 µM Pb 2+ applied simultaneously with re-added calcium reduced immediate<br />

CRAC to 70% or 37% <strong>of</strong> control value, respectively.<br />

During CRAC a large influx <strong>of</strong> Pb 2+ occurred, leading to a 2.7-fold faster increase in<br />

the FURA-2 excitation ratio. These effects were exclusive <strong>of</strong> any inhibitory action<br />

<strong>of</strong> Pb 2+ on calcium ATPase activity.<br />

Not applicable Long et al. (1990)<br />

Not applicable Schanne et al.<br />

(1989)<br />

Not applicable Schirrmacher et al.<br />

(1998)<br />

Not applicable Wiemann et al.<br />

(1999)


AX5-131<br />

Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb nitrate<br />

0–150 µM<br />

Up to 72 hr<br />

In medium<br />

Pb acetate<br />

0–25 µM<br />

48 hr<br />

In medium<br />

Pb glutamate<br />

4.5 H 10 −5 to<br />

4.5 H 10 −7 M<br />

2, 4, or 6 days<br />

In medium<br />

Pb glutamate<br />

4.5 H 10 −5 M–10 −7 M<br />

1,3, or 5 days<br />

incubation<br />

In medium<br />

Mice (bone<br />

cell isolation<br />

from parietal<br />

bones)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Human<br />

Dental Pulp<br />

Cells<br />

Pb 2+ concentrations <strong>of</strong> 50 µM and above stimulated release <strong>of</strong> hydroxyproline and<br />

previously incorporated 45 Ca from organ culture. This did not occur in bone<br />

inactivated by freezing and thawing. Eel calcitonin, bafilomycin A1, and scopadulcic<br />

acid B significantly inhibited Pb mediated 45 Ca release. There was a high correlation<br />

between 45 Ca and PGE 2 release (p < 0.001), inferring Pb-induced bone resorption<br />

mediated by PGE 2. This was further supported by the significant depression <strong>of</strong> Pbstimulated<br />

45 Ca release that occurred with concurrent exposure to 10 µM <strong>of</strong> either<br />

indomethacin or flurbipr<strong>of</strong>en, both inhibitors <strong>of</strong> cyclooxygenase.<br />

Osteocalcin production in cells treated with 100 pg 1,25-dihydroxyvitamin D 3/mL <strong>of</strong><br />

medium and 0 µM Pb 2+ <strong>for</strong> 16, 24, or 36 h was 20.1 ± 2.1, 23.5 ± 3.4, 26.1 ± 2.5 in cell<br />

digests, and 87.2 ± 3.3, 91.6 ± 6.7, 95.1 ± 5.2 in the medium, respectively. The<br />

presence <strong>of</strong> 25 µM Pb 2+ in the medium, reduced osteocalcin levels to as low as 30% <strong>of</strong><br />

control levels.<br />

Cells treated with 0, 5, 10, or 25 µM Pb acetate <strong>for</strong> 24 h, followed by an additional<br />

24 h exposure to 0 or 100 pg <strong>of</strong> 1,25-dihydroxyvitamin D3 and continued Pb 2+<br />

exposure, resulted in a concentration-dependent reduction <strong>of</strong> 1,25-dihydroxyvitamin<br />

D3-stimulated osteocalcin secretion. 10 µM Pb resulted in medium osteocalcin levels<br />

similar to control levels, however, 25 µM Pb resulted in about a 30% decrease.<br />

Cellular osteocalcin levels were unaffected.<br />

In the presence <strong>of</strong> serum in the cultures, concentrations <strong>of</strong> Pb 2+ less than 4.5 H 10 −5 M<br />

had no effect on cell proliferation. In the absence <strong>of</strong> serum, 4.5 H 10 −7 M Pb 2+<br />

increased proliferation at Day 4 and 4.5 H 10 −6 M Pb 2+ inhibited proliferation at Day 6.<br />

Pb exposure <strong>for</strong> 48 h (4.5 H 10 −6 M) significantly (p < 0.01) increased total protein<br />

production in cells and media <strong>of</strong> cultures labeled with [ 3 H] proline, but did not<br />

increase collagen production. Protein synthesis and osteonectin were enhanced in<br />

cells following Pb 2+ exposure.<br />

All concentrations significantly increased cell proliferation on Day 1, 3, and 5 <strong>of</strong><br />

exposure in serum free conditions. Pb exposure resulted in dose-dependent decrease<br />

in intracellular protein and procollagen I production over 5 days. In presence <strong>of</strong> serum<br />

only, 4.5 H 10 −5 M Pb 2+ significantly increased protein production, however, at that<br />

same concentration Pb significantly decreased osteocalcin production (i.e., reduced the<br />

level <strong>of</strong> osteocalcin by 55% at 12 hr).<br />

Not applicable Miyahara et al.<br />

(1995)<br />

Not applicable Long et al. (1990)<br />

Not applicable Sauk et al. (1992)<br />

Not applicable Thaweboon et al.<br />

(2002)


AX5-132<br />

Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb glutamate<br />

5–20 µM<br />

48 hr<br />

In medium<br />

Pb<br />

0.5 to 5 µM<br />

40 min<br />

In medium<br />

Pb nitrate<br />

5 H 10 −4 to 5 H 10 −15 M<br />

24 h<br />

In medium<br />

Pb acetate<br />

2 to 200 µM<br />

72 h<br />

In medium<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Cells treated with 0, 5, 10, or 20 µM Pb acetate <strong>for</strong> 24 h, followed by an additional<br />

24 h exposure to 0 or 100 pg <strong>of</strong> 1,25-dihydroxyvitamin D 3 and continued Pb 2+<br />

exposure, resulted in a significant (p < 0.05 or less) reduction <strong>of</strong> osteocalcin secretion,<br />

both in the presence and absence <strong>of</strong> 1,25-dihydroxyvitamin D 3 at all Pb 2+<br />

concentrations. This effect is not mediated by PKC.<br />

1 and 5 µM Pb 2+ significantly increased [Ca 2+ ] i in the absence <strong>of</strong> 1,25dihydroxyvitamin<br />

D 3 and significantly reduced the peak elevation in [Ca 2+ ] i induced<br />

by 1,25-dihydroxyvitamin D3.<br />

Simultaneous treatment <strong>of</strong> previously unexposed cells to Pb 2+ and 1,25dihydroxyvitamin<br />

D3 produced little reduction in the 1,25-dihydroxyvitamin D 3induced<br />

45 Ca uptake, while 40 min <strong>of</strong> treatment with Pb 2+ be<strong>for</strong>e addition <strong>of</strong> 1,25dihydroxyvitamin<br />

D3 significantly reduced the 1,25-dihydroxyvitamin D 3-induced<br />

increase in 45 Ca influx.<br />

Osteocalcin secretion significantly reduced below control values by culture with 1 µM<br />

Pb 2+ in the presence or absence <strong>of</strong> added 1,25-dihydroxyvitamin D 3 or 1,25dihydroxyvitamin<br />

D 3 and IGF-I. Inhibition <strong>of</strong> osteocalcin secretion was almost<br />

complete in either hormone-stimulated or basal cultures with the addition <strong>of</strong> 100 µM<br />

Pb 2+ . Cellular alkaline phosphatase activity paralleled those <strong>of</strong> osteocalcin, though<br />

there was no response to IGF-I alone or in combination with 1,25-dihydroxyvitamin<br />

D 3. Pb 2+ at 10 −15 , 10 −12 , and 10 −9 to 10 −7 M did not influence DNA contents <strong>of</strong> cell<br />

cultures, but 1 µM significantly (p < 0.05) inhibited basal cultures and those with IGF-<br />

I + D3. Cell cultures exposed to 1,25-dihydroxyvitamin D 3 and Pb 2+ were inhibited at<br />

10 µM Pb 2+ .<br />

Pb (2 to 200 µM) had no effect on cell number or DNA and protein synthesis.<br />

Alkaline phosphatase activity was significantly reduced (p < 0.001) by Pb in a dose-<br />

and time-dependent manner.<br />

Pb Concentration. Alkaline Phosphatase Inhibition<br />

2 µM. 10.0 ± 1.1%<br />

20 µM. 22.0 ± 6.4%<br />

200 µM. 57.8 ± 8.8%<br />

Reductions in alkaline phosphatase mRNA levels mirrored Pb 2+ -induced inhibition <strong>of</strong><br />

enzyme activity.<br />

Not applicable Guity et al. (2002)<br />

Not applicable Schanne et al.<br />

(1992)<br />

Not applicable Angle et al. (1990)<br />

Not applicable Klein and Wiren<br />

(1993)


AX5-133<br />

Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Unidentified Pb 2+<br />

Various incubation<br />

times<br />

Not applicable<br />

Unidentified Pb 2+<br />

Various incubation<br />

times<br />

Not applicable<br />

Pb acetate<br />

10 µM<br />

2 h<br />

In medium<br />

Pb acetate<br />

5 or 25 µM<br />

Up to 24 h<br />

In medium<br />

Pb acetate<br />

5 or 25 µM<br />

20 h<br />

In medium<br />

Bovine<br />

(Bovinederived<br />

osteocalcin)<br />

Bovine<br />

(Bovinederived<br />

osteocalcin)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Binding studies <strong>of</strong> Ca 2+ to osteocalcin suggested a single binding site with a<br />

dissociation constant (Kd) <strong>of</strong> 7 ± 2 µM <strong>for</strong> Ca-osteocalcin. Competitive displacement<br />

experiments by addition <strong>of</strong> Pb 2+ indicated the Kd <strong>for</strong> Pb-osteocalcin is 1.6 ± 0.42 nM,<br />

~3 orders <strong>of</strong> magnitude higher.<br />

Circular dichroism indicated Pb 2+ binding induced a structural change in osteocalcin<br />

similar to that found in Ca 2+ binding, but at 2 orders <strong>of</strong> magnitude lower concentration.<br />

Pb 2+ has 4 orders <strong>of</strong> magnitude tighter binding to osteocalcin (Kd = 0.085 µM) than<br />

Ca 2+ (Kd = 1.25 mM). Hydroxyapatite binding assays showed similar increased<br />

adsorption <strong>of</strong> Pb 2+ and Ca 2+ to hydroxyapatite, but Pb 2+ adsorption occurred at a<br />

concentration 2–3 orders lower than Ca 2+ .<br />

Pb 2+ treatment reduced the unidirectional rate <strong>of</strong> ATP synthesis (P i to ATP) by a factor<br />

<strong>of</strong> 6 or more (∆M/M o: Control = 0.18 ± 0.04, Pb 2+ < 0.03). Intracellular free Mg 2+<br />

concentration decreased 21% after 2 h <strong>of</strong> 10 µM Pb 2+ treatment (0.29 ± 0.02 mM prior<br />

to Pb 2+ treatment and 0.23 ± 0.02 mM after 2 h <strong>of</strong> Pb 2+ treatment, p < 0.05).<br />

5 µM Pb 2+ significantly altered effect <strong>of</strong> EGF on intracellular calcium metabolism.<br />

In cells treated with 5 µM Pb 2+ and 50 ng/mL EGF, there was a 50% increase in total<br />

cell calcium over cells treated with 50 ng/mL EGF alone.<br />

Treatment with 400 ng/mL culture medium <strong>for</strong> 1 h or with 25 µM Pb 2+ <strong>for</strong> 20 h<br />

increased total cell calcium:<br />

Treatment Cell Calcium<br />

Control 7.56 ± 1.05 nmol/mg protein<br />

PTH (400 ng/mL) 23.28 ± 1.40* nmol/mg protein<br />

Pb (25 µM) 11.37 ± 0.57* nmol/mg protein<br />

PTH + Pb 37.88 ± 4.21* nmol/mg protein<br />

* p # 0.05 from control<br />

Not applicable Dowd et al. (1994)<br />

Not applicable Dowd et al. (2001)<br />

Not applicable Dowd et al. (1990)<br />

Not applicable Long and Rosen<br />

(1992)<br />

Not applicable Long et al. (1992)


AX5-134<br />

Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

10 −11 to 10 −7 M<br />

3 min<br />

In medium<br />

Pb acetate<br />

0.5 to 60 µM<br />

24 to 48 h<br />

In medium<br />

Pb acetate or Pb<br />

chloride<br />

0.1 to 200 µM<br />

24 h to 6 days<br />

In medium<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Human<br />

Osteosarcoma<br />

Cells (HOS<br />

TE 85)<br />

and<br />

Rat<br />

Osteosarcoma<br />

Cells<br />

(ROS 17/2.8)<br />

Chick growth<br />

plate<br />

chondrocytes<br />

Treatment <strong>of</strong> ROS cells with Pb at 1 or 5 µM concentrations produced a rise in [Ca 2+ ] i<br />

to 170 nM and 230 nM, respectively, over the basal level <strong>of</strong> 125 nM. An elevation in<br />

[Ca 2+ ] i to 210 nM occurred during treatment with an activator <strong>of</strong> PKC, phorbol 12myristate<br />

13-acetate (10 µM). Pretreatment with a selective inhibitor <strong>of</strong> PKC,<br />

calphostin C, did not change basal [Ca 2+ ] i, but prevented the Pb-induced rise in [Ca 2+ ] i.<br />

Free Pb 2+ activated PKC in a range from 10 −11 to 10 −7 M, with a Kcat (activation<br />

constant) <strong>of</strong> 1.1 H 10 −10 M and a maximum velocity (Vmax) <strong>of</strong> 1.08 nmol/mg/min<br />

compared with Ca activation <strong>of</strong> PKC over a range <strong>of</strong> 10 −8 to 10 −3 M, with a Kcat <strong>of</strong><br />

3.6 H 10 −7 M, and a Vmax <strong>of</strong> 1.12 nmol/mg/min.<br />

HOS TE 85 Cells<br />

Inhibition <strong>of</strong> proliferation (IC 50) = 4 µM Pb<br />

Cytotoxicity = 20 µM Pb<br />

ROS 17/2.8 Cells<br />

Inhibition <strong>of</strong> proliferation (IC50) = 6 µM Pb<br />

Cytotoxicity = 20 µM Pb<br />

Highest Pb concentration in both cell types found in mitochondrial fraction.<br />

Growth plate chondrocytes were exposed to 3 or 30 µM <strong>for</strong> up to 6 days. Maximal<br />

inhibition <strong>of</strong> cell proliferation as measured by thymidine incorporation occurred after a<br />

3-day exposure to Pb. A similar 40% inhibition was found at both concentrations.<br />

Higher concentrations (up to 100 µM) did not produce further inhibition.<br />

In cultures treated <strong>for</strong> 24 h, Pb produced a dose-dependent inhibition <strong>of</strong> alkaline<br />

phosphatase, with 10 µM producing maximal inhibition (40–50% inhibition). Effects<br />

<strong>of</strong> Pb on proteoglycan synthesis were not found until after 48 h <strong>of</strong> exposure, with<br />

maximal effect after 72 h <strong>of</strong> exposure (tw<strong>of</strong>old, 30 µM). Pb exposure (10 to 200 µM)<br />

<strong>for</strong> 24 h produced a dose-dependent inhibition <strong>of</strong> both type <strong>II</strong> and type X collagen<br />

synthesis.<br />

Not applicable Schanne et al.<br />

(1997)<br />

Not applicable Angle et al. (1993)<br />

Not applicable Hicks et al. (1996)


AX5-135<br />

Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects <strong>of</strong> <strong>Lead</strong><br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

0.1 to 30 µM<br />

24 h<br />

In medium<br />

Abbreviations<br />

Chicken<br />

growth plate<br />

and sternal<br />

chondrocytes<br />

Pb—lead<br />

µCi—microCurie<br />

IU—international units<br />

hr—hour<br />

OB—osteoblast<br />

5F-BAPTA—1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N’,N’-tetraacetic acid<br />

[Pb 2+ ]i—free intracellular lead<br />

FURA-2—1-[6-Amino-2-(5-carboxy-2-oxazolyl)-5-benz<strong>of</strong>uranyloxy]-2-(2-amino-5methylphenoxy)<br />

ethane-N,N,N',N'-tetraacetic acid<br />

M—molar<br />

DNA—deoxyribonucleic acid<br />

∆M—decrease in magnetization <strong>of</strong> intracellular Pi upon prolonged saturation <strong>of</strong> gammaphosphate<br />

<strong>of</strong> ATP<br />

mM—millimolar<br />

Kcat—activation constant<br />

IC50—inhibitory concentration 50%<br />

mg—milligram<br />

210<br />

Pb—lead-210 radionuclide<br />

EM—experimental medium<br />

mU—milliunits<br />

45<br />

Ca—calcium-45 radionuclide<br />

CRAC—calcium release activated calcium reflux<br />

pg—picogram<br />

mRNA—messenger ribonucleic acid<br />

ng—nanogram<br />

A dose-dependent inhibition <strong>of</strong> thymidine incorporation into growth plate<br />

chondrocytes was found with exposure to 1–30 µM Pb <strong>for</strong> 24 h. A maximal 60%<br />

reduction occurred at 30 µM. Pb blunted the stimulatory effects on thymidine<br />

incorporation produced by TGF-β1 (24% reduction) and PTHrP (19% reduction),<br />

however, this effect was less than with Pb alone. Pb (1 and 10 µM) increased type X<br />

collagen in growth plate chondrocytes ~5.0-fold and 6.0-fold in TGF-β1 treated<br />

cultures and 4.2-fold and 5.1-fold in PTHrP treated cultures when compared with<br />

controls, respectively. Pb exposure alone reduced type X collagen expression by<br />

70–80%.<br />

Vmax—maximum velocity<br />

TGF-β1—trans<strong>for</strong>ming growth factor-beta 1<br />

mL—milliliter<br />

i.v.—intravenous<br />

CM—control medium<br />

µM—micromolar<br />

ng—nanogram<br />

[Ca 2+ ]i —free intracellular calcium<br />

PGE2—prostaglandin E2<br />

PKC—protein kinase C<br />

Kd—dissociation constant<br />

nmol—nanomole<br />

HOS TE 85 cells—human osteosarcoma cells<br />

PTHrP—parathyroid hormone-related protein<br />

GD—gestational day<br />

PTH—parathyroid hormone<br />

min—minute<br />

OC—osteoclast<br />

ROS 17/2.8—rat osteosarcoma cells<br />

nM—nanomolar<br />

h—hour<br />

IGF-I—insulin growth factor I<br />

ATP—adenosine triphosphate<br />

EGF—epidermal growth factor<br />

Not applicable Zuscik et al.<br />

(2002)


AX5-136<br />

Table AX5-8.4. Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic Conditions<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

200 µg/mL<br />

105 days prior to mating<br />

or 105 days prior to<br />

mating and during<br />

gestation and lactation<br />

(160 days)<br />

In drinking water<br />

Pb acetate<br />

12 mM<br />

8 wks prior to mating<br />

and during gestation<br />

In drinking water<br />

Pb acetate<br />

100 ppm<br />

(A) Exposure <strong>for</strong> 158 ±<br />

2 days from 21 days <strong>of</strong><br />

age to midlactation; (B)<br />

Exposure 144 ± 2 days<br />

from day 21 up to<br />

delivery; (C) Exposure<br />

only during lactation;<br />

(D, E, and F) groups <strong>of</strong><br />

nonpregnant rats<br />

exposed <strong>for</strong> periods<br />

equivalent to groups A,<br />

B and C, respectively.<br />

In drinking water<br />

Mice Results suggested very little Pb was transferred from mother to fetus during<br />

gestation, however, Pb transferred in milk and retained by the pups accounted<br />

<strong>for</strong> 3% <strong>of</strong> the maternal body burden <strong>of</strong> those mice exposed to Pb prior to<br />

mating only. The amount <strong>of</strong> Pb retained in these pups exceeded that retained<br />

in the mothers, suggesting lactation effectively transfers Pb burden from<br />

mother to suckling <strong>of</strong>fspring. Transfer <strong>of</strong> Pb from mothers was significantly<br />

higher when Pb was supplied continuously in drinking water, rather than<br />

terminated prior to mating.<br />

Rat Considerably higher lactational transfer <strong>of</strong> Pb from rat dams compared to<br />

placental transfer was reported. Continuous exposure <strong>of</strong> rat dams to Pb until<br />

day 15 <strong>of</strong> lactation resulted in milk Pb levels 2.5 times higher than in whole<br />

blood, while termination <strong>of</strong> maternal Pb exposure at parturition yielded<br />

equivalent blood and milk levels <strong>of</strong> Pb, principally from Pb mobilized from<br />

maternal bone.<br />

Rat In rats exposed to Pb 144 days prior to lactation (B), the process <strong>of</strong> lactation<br />

itself elevated blood Pb and decreased bone Pb, indicating mobilization <strong>of</strong> Pb<br />

from bone as there was no external source <strong>of</strong> Pb during the lactation process.<br />

Rats exposed to Pb <strong>for</strong> 158 days (A)(144 days prior to lactation and 14 days<br />

during lactation) also experienced elevated blood Pb levels and loss <strong>of</strong> Pb from<br />

bone. Pb exposure only during the 14 days <strong>of</strong> lactation was found to<br />

significantly increase intestinal absorption and deposition (17 fold increase) <strong>of</strong><br />

Pb into bone compared to nonpregnant rats, suggesting enhanced absorption <strong>of</strong><br />

Pb takes place during lactation. The highest concentration <strong>of</strong> Pb in bone was<br />

found in nonpregnant, nonlactating control animals, with significantly<br />

decreased bone Pb in lactating rats secondary to bone mobilization and transfer<br />

via milk to suckling <strong>of</strong>fspring.<br />

Not given Keller and Doherty<br />

(1980)<br />

Concentration (µg/l) in<br />

whole blood at day 15 <strong>of</strong><br />

lactation:<br />

Controls = 14 ± 4; Pbexposed<br />

until parturition =<br />

320 ± 55; Pb-exposed<br />

until day 15 <strong>of</strong> lactation =<br />

1260 ± 171*<br />

*p < 0.001 compared with<br />

dams at parturition.<br />

Concentration (µg/dL) in<br />

whole blood at day 14 <strong>of</strong><br />

lactation or equivalent:<br />

Group A = 31.2 ± 1.1;<br />

Group B = 28.0 ± 1.7;<br />

Group D = 27.3 ± 2.2;<br />

Group E = 24.7 ± 1.2<br />

Palminger Hallén<br />

et al. (1996)<br />

Maldonado-Vega<br />

et al. (1996)


AX5-137<br />

Table AX5-8.4 (cont’d). Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic Conditions<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

100 ppm<br />

(A) Exposure <strong>for</strong> 158 ±<br />

2 days from 21 days<br />

through 14 days <strong>of</strong><br />

lactation; (B)<br />

Nonpregnant control<br />

Group A; (C) Exposure<br />

144 ± 2 days from day<br />

21 up to delivery; (D)<br />

Nonpregnant control<br />

Group C; (E) Lactating<br />

rats not exposed to Pb;<br />

(F) Nonpregnant rats<br />

not exposed to Pb.<br />

In drinking water<br />

Pb acetate<br />

250 mg/mL<br />

Beginning at 5 wks <strong>of</strong><br />

age, rats exposed to Pb<br />

<strong>for</strong> 5 wks, followed by<br />

no additional exposure.<br />

In drinking water<br />

Rat When dietary calcium was reduced from the normal 1 to 0.05%, bone calcium<br />

concentration decreased by 15% and bone Pb concentration decreased by 30%<br />

during the first 14 days <strong>of</strong> lactation. In nonlactating rats on the 0.05% calcium<br />

diet, there were also decreases in bone calcium, but no incremental bone<br />

resorption nor Pb efflux from bone, suggesting the efflux from bone during<br />

lactation was related to bone resorption. Enhancement <strong>of</strong> calcium (2.5%) in<br />

the diet <strong>of</strong> lactating rats increased calcium concentration in bone by 21%, but<br />

did not decrease bone resorption, resulting in a 28% decrease in bone Pb<br />

concentration and concomitant rise in systemic toxicity.<br />

Rat Demonstrated adverse effects in rat <strong>of</strong>fspring born to females whose exposure<br />

to Pb ended well be<strong>for</strong>e pregnancy. Five wk-old-female rats given Pb acetate<br />

in drinking water (250 mg/mL) <strong>for</strong> five wks, followed by a one mo period<br />

without Pb exposure be<strong>for</strong>e mating. To test the influence <strong>of</strong> dietary calcium<br />

on Pb absorption and accumulation, some pregnant rats were fed diets<br />

deficient in calcium (0.1%) while others were maintained on a normal calcium<br />

(0.5%) diet. All Pb-exposed dams and pups had elevated blood Pb levels;<br />

however, pups born to dams fed the diet deficient in calcium during pregnancy<br />

had higher blood and organ Pb concentrations compared to pups from dams<br />

fed the normal diet. Pups born to Pb-exposed dams had lower mean birth<br />

weights and birth lengths than pups born to non-Pb-exposed control dams<br />

(p < 0.0001), even after confounders such as litter size, pup sex, and dam<br />

weight gain were taken into account.<br />

Concentration (µg/dL) in<br />

whole blood at day 14 <strong>of</strong><br />

lactation or equivalent:<br />

Group B = 26.1 ± 2.1,<br />

Group A = 32.2 ± 2.7*;<br />

Group D = 23.8 ± 2.1,<br />

Group C = 28.2 ± 2.2*;<br />

Groups E and F = 5.1 ±<br />

0.4.<br />

* p < 0.01, compared to<br />

appropriate control<br />

Blood Pb concentration <strong>of</strong><br />

pups (µM): Low<br />

calcium/no Pb = 0.137 ±<br />

0.030 C ; Low calcium/Pb =<br />

1.160 ± 0.053 A ; Normal<br />

calcium/No Pb = 0.032 ±<br />

0.003 C ; Normal<br />

calcium/Pb = 0.771 ±<br />

0.056 B .<br />

Values that are not<br />

marked by the same letter<br />

are significantly different<br />

(p < 0.05).<br />

Maldonado-Vega<br />

et al. (2002)<br />

Han et al. (2000)


AX5-138<br />

Table AX5-8.4 (cont’d). Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic Conditions<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

1500 µg/Common<br />

Pb/kg/d<br />

~10 yrs, replaced by a<br />

204 Pb-enriched dose<br />

(50 days), then<br />

206 Pb-enriched dose<br />

(50 days), and finally a<br />

207 Pb-enriched dose<br />

(50 days, with reduced<br />

concentration)<br />

Orally, in gelatin<br />

capsule<br />

Pb acetate<br />

1300 to<br />

1500 µg/Common<br />

Pb/kg/d<br />

~10 yrs, replaced by a<br />

204 Pb-enriched dose<br />

(47 or 281 days), then<br />

206 Pb-enriched dose<br />

(50 or 105 days), and<br />

finally a 207 Pb-enriched<br />

dose (50 days, with<br />

650 µg concentration in<br />

only one primate)<br />

Orally, in gelatin<br />

capsule<br />

Nonhuman<br />

Primate<br />

Nonhuman<br />

Primate<br />

Sequential doses <strong>of</strong> Pb mixes enriched in stable isotopes ( 204 Pb, 206 Pb,<br />

and 207 Pb) were administered to a female cynomolgus monkey (Macaca<br />

fascicularis) that had been chronically administered a common Pb isotope mix.<br />

The stable isotope mixes served as a marker <strong>of</strong> recent, exogenous Pb exposure,<br />

while the chronically administered common Pb served as a marker <strong>of</strong><br />

endogenous (principally bone) Pb. From thermal ionization mass spectrometry<br />

analysis <strong>of</strong> the Pb isotopic ratios <strong>of</strong> blood and bone biopsies collected at each<br />

isotope change, and using end-member unmixing equations, it was determined<br />

that administration <strong>of</strong> the first isotope label allowed measurement <strong>of</strong> the<br />

contribution <strong>of</strong> historic bone stores to blood Pb. Exposure to subsequent<br />

isotopic labels allowed measurements <strong>of</strong> the contribution from historic bone<br />

Pb stores and the recently administered enriched isotopes that incorporated<br />

into bone. In general the contribution from the historic bone Pb (common Pb)<br />

to blood Pb level was constant (~20%), accentuated with spikes in total blood<br />

Pb due to the current administration <strong>of</strong> the stable isotopes. After cessation <strong>of</strong><br />

each sequential administration, the concentration <strong>of</strong> the signature dose rapidly<br />

decreased.<br />

Initial attempts to apply a single bone physiologically based model <strong>of</strong> Pb<br />

kinetics were unsuccessful until adequate explanation <strong>of</strong> these rapid drops in<br />

stable isotopes in the blood were incorporated. Revisions were added to<br />

account <strong>for</strong> rapid turnover <strong>of</strong> the trabecular bone compartment and slower<br />

turnover rates <strong>of</strong> cortical bone compartment, an acceptable model evolved.<br />

From this model it was reported that historic bone Pb from 11 yrs <strong>of</strong><br />

continuous exposure contributes ~17% <strong>of</strong> the blood Pb concentration at Pb<br />

concentration over 50 µg/dL, rein<strong>for</strong>cing the concept that the length <strong>of</strong> Pb<br />

exposure and the rates <strong>of</strong> past and current Pb exposures help determine the<br />

fractional contribution <strong>of</strong> bone Pb to total blood Pb levels. The turnover rate<br />

<strong>for</strong> cortical (~88% <strong>of</strong> total bone by volume) bone in the adult cynomolgus<br />

monkey was estimated by the model to be ~4.5% per yr, while the turnover<br />

rate <strong>for</strong> trabecular bone was estimated to be 33% per yr.<br />

Total blood Pb range:<br />

31.2 to 62.3 µg/100g.<br />

Inskip et al. (1996)<br />

Various O’Flaherty et al.<br />

(1998)


AX5-139<br />

Table AX5-8.4 (cont’d). Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic Conditions<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

1100 to<br />

1300 µg/Common<br />

Pb/kg/d<br />

~14 yrs, replaced by a<br />

204 Pb-enriched dose,<br />

206 Pb-enriched dose,<br />

and/or finally a<br />

207 Pb-enriched dose <strong>of</strong><br />

varied durations and<br />

concentrations.<br />

Orally, in gelatin<br />

capsule<br />

Pb acetate<br />

250 mg/L<br />

Exposure began either<br />

at 5, 10, or 15 wks <strong>of</strong><br />

age and continued <strong>for</strong> a<br />

total <strong>of</strong> 5 wks.<br />

Drinking water<br />

Nonhuman<br />

primate<br />

Using the method <strong>of</strong> sequential stable isotope administration examined flux <strong>of</strong><br />

Pb from maternal bone during pregnancy <strong>of</strong> 5 female cynomolgus monkeys.<br />

Blood Pb levels in maternal blood attributable to Pb from mobilized bone were<br />

reported to drop 29 to 56% below prepregnancy baseline levels during the first<br />

trimester <strong>of</strong> pregnancy. This was ascribed to the known increase in maternal<br />

fluid volume, specific organ enlargement (e.g., mammary glands, uterus,<br />

placenta), and increased metabolic activity that occurs during pregnancy.<br />

During the second and third trimesters, when there is a rapid growth in the<br />

fetal skeleton and compensatory demand <strong>for</strong> calcium from the maternal blood,<br />

the Pb levels increased up to 44% over pre-pregnancy levels. With the<br />

exception <strong>of</strong> one monkey, blood Pb concentrations in the fetus corresponded to<br />

those found in the mothers, both in total Pb concentration and proportion <strong>of</strong> Pb<br />

attributable to each isotopic signature dose (common = 22.1% vs. 23.7%,<br />

204 Pb = 6.9% vs. 7.4%, and 206 Pb = 71.0% vs. 68.9%, respectively). Between<br />

7 and 25% <strong>of</strong> Pb found in fetal bone originated from maternal bone, with the<br />

balance derived from oral dosing <strong>of</strong> the mothers with isotope during<br />

pregnancy.<br />

In <strong>of</strong>fspring from a low Pb exposure control monkey (blood Pb


AX5-140<br />

Table AX5-8.4 (cont’d). Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic Conditions<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

50 ppm<br />

11 mo<br />

Drinking water<br />

Pb acetate<br />

0, 2, or 10 mg/kg/d<br />

9.5 mo<br />

Drinking water<br />

Pb acetate<br />

7 yrs total<br />

Drinking water<br />

Pb (type unidentified)<br />

occurring naturally in<br />

diet (0.258 ng/mg dry<br />

wt) and water<br />

(5.45 ppb).<br />

Exposure from age<br />

1 mo up to 958 days.<br />

Drinking water and diet<br />

Rat Studied differences in tissue distribution <strong>of</strong> Pb in adult and old rats. Adult<br />

(8 mo old) and old (16 mo old) rats were exposed to 50 ppm Pb acetate in<br />

drinking water <strong>for</strong> 11 mo at which time the experiment was completed. Bone<br />

(femur) Pb levels in older rats were found to be less than those in younger rats,<br />

however, blood Pb levels were higher in the older rats. Brain Pb concentration<br />

in the older rats exposed to Pb were significantly higher, and brain weight<br />

significantly less than the brain Pb concentration and weights <strong>of</strong> unexposed<br />

older control rats or adult rats exposed to Pb, suggesting a potential<br />

detrimental effect. Authors suggested that a possibility <strong>for</strong> the observed<br />

differences in tissue concentrations <strong>of</strong> Pb was due to changes in the capacity <strong>of</strong><br />

bone to store Pb with advanced age.<br />

Rat Examined kinetic and biochemical responses <strong>of</strong> young (21 days old), adult<br />

(8 mo old), and old (16 mo old) rats exposed to Pb at 0, 2, or 10 mg Pb<br />

acetate/kg/d over a 9.5 mo experimental period. Results suggested older rats<br />

may have increased vulnerability to Pb due to increased exposure <strong>of</strong> tissues to<br />

Pb and greater sensitivity <strong>of</strong> the tissues to the effects <strong>of</strong> Pb.<br />

Nonhuman<br />

primate<br />

In studies <strong>of</strong> bone Pb metabolism in a geriatric, female nonhuman primates<br />

exposed to Pb ~10 yrs previously, there were no significant changes in bone<br />

Pb level over a 10 mo observation period as measured by 109 CD K X-ray<br />

fluorescence. The mean half-life <strong>of</strong> Pb in bone <strong>of</strong> these animals was found to<br />

be 3.0 ± 1.0 yrs, consistent with data found in humans, while the endogenous<br />

exposure level due to mobilized Pb was<br />

0.09 ± 0.02 µg/dL blood.<br />

Mice The Pb content <strong>of</strong> femurs increased by 83% (values ranged from 0.192 to 1.78<br />

ng Pb/mg dry wt), no significant relationship was found between Pb and bone<br />

density, bone collagen, or loss <strong>of</strong> calcium from bone. The results suggest<br />

against low levels <strong>of</strong> bone Pb contributing to the osteopenia observed normally<br />

in C57BL/6J mice.<br />

Approximate median<br />

values after 6 mo <strong>of</strong><br />

exposure:<br />

Adult rats : 23 µg/dL<br />

Old rats: 31 µg/dL<br />

After 11 mo <strong>of</strong> exposure:<br />

Adult rats: 16 µg/dL<br />

Old rats: 31 µg/dL<br />

Various from ~1 µg/dL<br />

up to 45 µg/dL<br />

Historic concentrations<br />

during exposure: 44 to<br />

89 µg/100 mL.<br />

Cory-Slechta et al.<br />

(1989)<br />

Cory-Slechta<br />

(1990b)<br />

McNeill et al.<br />

(1997)<br />

None given Massie and Aiello<br />

(1992)


AX5-141<br />

Table AX5-8.4. (cont’d). Bone <strong>Lead</strong> as a Potential Source <strong>of</strong> Toxicity in Altered Metabolic Conditions<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

250 mg/l<br />

Exposure <strong>for</strong> 5 wks<br />

Drinking water<br />

Pb acetate<br />

250 µg/l<br />

14 days<br />

Drinking water<br />

Abbreviations<br />

µg—microgram<br />

mL—milliliter<br />

%—percent<br />

mM—millimolar<br />

l—liter<br />

ppm—parts per million<br />

dL—deciliter<br />

Rat Rats were exposed to Pb <strong>for</strong> 5 wks, followed by a 4 wk washout period<br />

without Pb to allow primarily accumulation in the skeleton. Rats were then<br />

randomly assigned to a weight maintenance group (WM), a moderate weight<br />

loss (MWL) group (70% <strong>of</strong> maintenance diet), or a substantial weight loss<br />

(SWL) group (40% <strong>of</strong> maintenance diet) <strong>for</strong> a 4 wk period. At the end <strong>of</strong> this<br />

experimental period the blood and bone levels <strong>of</strong> Pb did not differ between<br />

groups, however, the amount and concentration <strong>of</strong> Pb in the liver increased<br />

significantly.<br />

Treatment Group Pb (nmol/g)<br />

Femur WM 826 ± 70<br />

MWL 735 ± 53<br />

SWL 935 ± 84<br />

Spinal Column Bone WM 702 ± 67<br />

MWL 643 ± 59<br />

SWL 796 ± 59<br />

Rat Study was undertaken to determine the effect <strong>of</strong> weight loss and exercise on<br />

the distribution <strong>of</strong> Pb. Weight loss secondary to dietary restriction was a<br />

critical factor elevating organ Pb levels and, contrary to prior study (Han et al.<br />

(1996)), elevated blood levels <strong>of</strong> Pb. No significant difference in organ or<br />

blood Pb concentrations were reported between the exercise vs. no exercise<br />

groups.<br />

WM = 1.25 ± 0.10 µM;<br />

MWL = 1.16 ± 0.10 µM;<br />

WM = 1.32 ± 0.10 µM;<br />

Graphs indicate<br />

concentrations ranging<br />

from 0.20 to 2.00 µM.<br />

mg—milligram<br />

µM—micromolar<br />

Pb—lead<br />

kg—kilogram<br />

g—gram<br />

204 206 207<br />

Pb, Pb, Pb—Stable isotopes <strong>of</strong> lead 204, 206, 207, respectively<br />

wt—weight<br />

ppb—parts per billion<br />

Han et al. (1996)<br />

Han et al. (1999)


AX5-142<br />

Table AX5-8.5. Uptake <strong>of</strong> <strong>Lead</strong> by Teeth<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

1 µg/kg body weight<br />

Single IP injection<br />

Pb aerosol<br />

77, 249, or 1546 µg/m 3<br />

<strong>for</strong> 50 to 70 days<br />

Inhalation<br />

Pb acetate<br />

0, 3, or10 ppm<br />

During pregnancy and<br />

21 days <strong>of</strong> lactation<br />

Drinking water<br />

Abbreviations<br />

µg—microgram<br />

kg—kilogram<br />

IP—intraperitoneal<br />

%—percent<br />

h—hour<br />

Rat Uptake <strong>of</strong> Pb label into incisors <strong>of</strong> suckling rats:<br />

0.7% <strong>of</strong> injected dose in 4 incisors <strong>of</strong> suckling rat after 24 h,<br />

1.43% after 192 h. 0.6% <strong>of</strong> injected dose in 4 incisors <strong>of</strong> adult after 24 h,<br />

0.88% after 192 h.<br />

Rat 11 micrograms Pb/g incisor taken up in animals exposed to 77 µg/m 3 <strong>for</strong><br />

70 days vs. 0.8 µg Pb/g in control animals<br />

13.8 µg Pb/g incisor in rats exposed to 249 µg/m 3 <strong>for</strong> 50 days<br />

153 µg Pb/g incisor in rats exposed to 1546 µg/m 3 <strong>for</strong> 50 days<br />

Rat Pb concentration in teeth <strong>of</strong> <strong>of</strong>fspring:<br />

0 ppm group–Incisors (1.3 ppm), 1st molars (0.3 ppm)<br />

3 ppm group–Incisors (1.4 ppm), 1st molars (2.7 ppm)<br />

10 ppm group–Incisors (13.3 ppm), 1st molars (11.4 ppm)<br />

m 3 —cubic meter<br />

Pb—lead<br />

g—gram<br />

ppm—parts per million<br />

Mean percent <strong>of</strong> dose after<br />

time:<br />

Suckling:<br />

3.04% after 24 h<br />

1.71% after 72 h<br />

1.52% after 144 h<br />

1.18% after 192 h<br />

Adult:<br />

6.40% after 24 h<br />

3.41% after 24 h<br />

1.92% after 24 h<br />

1.04% after 72 h<br />

0.72% after 144 h<br />

0.48% after 192 h<br />

Control: 2.6 µg/dL<br />

77 µg/m 3 : 11.5 µg/dL<br />

249 µg/m 3 : 24.1 µg/dL<br />

1546 µg/m 3 : 61.2 µg/dL<br />

Momčilović and<br />

Kostial (1974)<br />

Grobler et al. (1991)<br />

Not given Grobler et al. (1985)


AX5-143<br />

Table AX5-8.6. Effects <strong>of</strong> <strong>Lead</strong> on Enamel and Dentin Formation<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb “salt”<br />

0.075 mM/100 g ,<br />

0.15 mM/100 g or<br />

1.5 mM/100 g<br />

Single, SC injection<br />

Pb acetate<br />

30 mg/kg<br />

Single, i.v. injection<br />

Pb acetate<br />

3 mg/kg<br />

Single, i.v. injection<br />

Pb acetate<br />

0 mg/l, 34 mg/l, or<br />

170 mg/l<br />

70 days<br />

Drinking water<br />

Pb acetate<br />

40 mg/kg<br />

Single, IP injection<br />

Abbreviations<br />

Pb—lead<br />

mM—millimolar<br />

g—gram<br />

SC—subcutaneous<br />

mg—milligram<br />

kg—kilogram<br />

Rat 0.075 mM dose, no disruption <strong>of</strong> dentin and enamel.<br />

0.15 mM dose, mild mineralization disruption <strong>of</strong> dentin and enamel.<br />

1.5 mM dose, mild to moderate disruption <strong>of</strong> dentin and enamel.<br />

Rat Rapid rise in serum calcium and phosphorus after injection.<br />

Formation <strong>of</strong> a “Pb line” in growing dentin within 6 hr after injection.<br />

Not given Eisenmann and Yaeger<br />

(1969)<br />

Not given Appleton (1991)<br />

Rat Production <strong>of</strong> a hypomineralized band in dentin. Not given Appleton (1992)<br />

Rat Increased in relative amount <strong>of</strong> protein in enamel matrix.<br />

Significant (p < 0.05) decrease in microhardness values <strong>of</strong> groups exposed<br />

to Pb in regions <strong>of</strong> maturation enamel, but not fully mature enamel.<br />

Delay in enamel mineralization in animals exposed to Pb.<br />

Rat Significantly (p < 0.05) reduced eruption rates at various time points<br />

(days 8, 14, 16, 22, 24, 28) under hyp<strong>of</strong>unctional conditions.<br />

i.v.—intravenous<br />

l—liter<br />

ppm—parts per million<br />

IP—intraperitoneal<br />

µg—microgram<br />

dL—deciliter<br />

0 mg/l group: 0 ppm<br />

34 mg/l group:<br />

18.1 ppm<br />

170 mg/l group:<br />

113.3 ppm<br />

Days after injection<br />

0 days: 48 µg/dL<br />

10 days: 37 µg/dL<br />

20 days: 28 µg/dL<br />

30 days: 16 µg/dL<br />

(Values estimated from<br />

graph)<br />

Gerlach et al. (2002)<br />

Gerlach et al. (2000b)


AX5-144<br />

Table AX5-8.7. Effects <strong>of</strong> <strong>Lead</strong> on Dental Pulp Cells<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb glutamate<br />

4.5 H 10 −5 M–10 −7 M<br />

1,3, or 5 days<br />

incubation<br />

Abbreviations<br />

Pb—lead<br />

M—molar<br />

Human<br />

Dental<br />

Pulp Cells<br />

All concentrations significantly increased cell proliferation on Day 1, 3 and<br />

5 <strong>of</strong> exposure in serum free conditions. Pb exposure resulted in dosedependent<br />

decrease in intracellular protein and procollagen I production<br />

over 5 days. In presence <strong>of</strong> serum only 4.5 H 10 −5 M significantly increased<br />

protein production. Pb significantly decreased osteocalcin production.<br />

Not applicable Thaweboon et al. (2002)


AX5-145<br />

Table AX5-8.8. Effects <strong>of</strong> <strong>Lead</strong> on Teeth—Dental Caries<br />

Compound<br />

Dose/Concentration<br />

Duration Exposure<br />

Route Species Effects Blood Level Reference<br />

Pb acetate<br />

0.5 mEq<br />

84 days males<br />

98 days females<br />

Drinking water<br />

Pb acetate<br />

34 ppm<br />

Pre- and perinatal<br />

Drinking water<br />

Pb acetate<br />

10 or 25 ppm Pb<br />

3 wks<br />

Drinking water<br />

Abbreviations<br />

mEq—milliequivalents<br />

d—days<br />

ppm—parts per million<br />

%—percent<br />

µg—microgram<br />

dL—deciliter<br />

Hamster Significant increase in dental caries in male hamsters only<br />

(85 mean molar caries score control vs. 118 <strong>for</strong> Pb exposed).<br />

No significant difference in dental caries in female hamsters<br />

(68 mean molar caries score control vs. 85 <strong>for</strong> Pb exposed).<br />

Rat Pb exposure resulted in an almost 40% increase in the<br />

prevalence <strong>of</strong> caries and nearly 30% decrease in stimulated<br />

parotid salivary gland function.<br />

Rat When 15 ppm fluoride was concurrently given in diet, Pb did<br />

not increase prevalence <strong>of</strong> caries.<br />

Not given Wisotzky and Hein (1958)<br />

Control:


ANNEX TABLES AX5-9<br />

AX5-146


AX5-147<br />

Nature <strong>of</strong><br />

Exposure<br />

Table AX5-9.1. Studies on <strong>Lead</strong> Exposure and Immune Effects in Humans<br />

Dose or Blood <strong>Lead</strong> Levels<br />

(BLLs) Sample Population Reported Effects Reference<br />

Environmental 10.1–48.2 µg/L (BLL) 2nd grade children living near<br />

industrial waste incinerator or other<br />

industries causing pollution<br />

Occupational 22 µg/dL: 30 µg/dL—Correlation <strong>of</strong> BLL with serum IgE.<br />

For employees less than 30 yrs old, IL-4 was lower when BLL >30 µg/dL.<br />

Indirect (PHA) macrophage activation.<br />

NO production negatively associated with BLL.<br />

With proximity closest to smelter monocytes had increased superoxide anion<br />

production by indirect and direct activation (positive correlation with BLL–<br />

stronger <strong>for</strong> boys than girls).<br />

Percent <strong>of</strong> CD4 + and CD4 + CD+ cells decreased while CD8 + increased.<br />

Male Pb-exposed workers PHA-mitogen response decreased; and IFN-gamma production increased.<br />

No effect on NK cytotox.<br />

96 females<br />

121 males<br />

(3–6 yrs old)<br />

30 Pb workers from battery<br />

manufacturing plant (43 males and<br />

21 females)<br />

25 male storage battery workers<br />

exposed >6 mo; age 33 ± 8.5 yrs<br />

IgG and IgM lower in high BLL group ($9.52 µg/dL).<br />

IgE greater in high BLL group (P < 0.10).<br />

No difference among males but females exposed to higher Pb had significant<br />

decreases in IgG and IgM and increased in IgE.<br />

Correlation <strong>of</strong> BLL and serum IgE r = 0.48; P = 0.002.<br />

Increased percentage <strong>of</strong> monocytes while percentage <strong>of</strong> B-cells, numbers <strong>of</strong><br />

lymphocytes, monocytes, and granulocytes decreased.<br />

Decreased blood hemoglobin, TCD4 + cells, IgG, IgM, C3 and C4 compliment<br />

proteins.<br />

Increased zinc protoporphyrin.<br />

Impaired neutrophil chemotaxis and random migration.<br />

Karmaus et al.<br />

(2005)<br />

Heo et al.<br />

(2004)<br />

Pineda-<br />

Zavaleta et al.<br />

(2004)<br />

Zhao et al.<br />

(2004)<br />

Mishra et al.<br />

(2003)<br />

Sun et al.<br />

(2003)<br />

Sun et al<br />

.(2003)<br />

Basaran and<br />

Undeger<br />

(2000)


AX5-148<br />

Nature <strong>of</strong><br />

Exposure<br />

Table AX5-9.1 (cont’d). Studies on <strong>Lead</strong> Exposure and Immune Effects in Humans<br />

Dose or Blood <strong>Lead</strong> Levels<br />

(BLLs) Sample Population Reported Effects Reference<br />

Environmental 1.7–16.1 µg/dL<br />

(Range in 15 µg/dL<br />

>3 yrs <strong>of</strong> age–no differences.<br />

Sarasua et al.<br />

(2000)<br />

Correlation <strong>of</strong> blood Pb levels and serum IgE levels in Missouri children. Lutz, et al.<br />

(1999)<br />

No major effects; only subtle effects.<br />

Elev. B cells elevated CD4+/CD45RA+ cells.<br />

Decr. Serum IgG.<br />

T cell populations,<br />

Naïve T cells correlated positively with blood PB levels. Memory T cells<br />

reduced with Pb.<br />

Absolute and relative numbers <strong>of</strong> CD4+ T cells reduced in exposed group.<br />

IgG, IgM C3 and C4 serum levels all lower in workers.<br />

Pinkerton<br />

et al. (1998)<br />

Sata et al.<br />

(1998)<br />

Undeger et al.<br />

(1996)<br />

No changes in serum Igs <strong>of</strong> PHA response <strong>of</strong> PBMC. Queiroz et al.<br />

(1994)<br />

T cell phenotypes and response—Pb reduced relative CD3+ cells and relative and<br />

absolute CD4+ cells also reduced PHA (high Pb)and PWM mitogen responses,<br />

reduced MLR also(high Pb).<br />

Fischbein<br />

et al. (1993)<br />

IgE positively correlated with BLL. Horiguchi<br />

et al. (1992)<br />

Impaired neutrophil migration.<br />

Impaired nitroblue tetrazolium positive neutrophils.<br />

Greater <strong>for</strong> those exposed up to 1 yr than those with longer exposure “safe” levels<br />

<strong>of</strong> Pb can still cause immunosuppression.<br />

Pb associated with greater IgG production after stimulation with PWM–not dose<br />

dependent.<br />

Queiroz et al.<br />

(1993)<br />

Borella and<br />

Giardino<br />

(1991)


AX5-149<br />

Nature <strong>of</strong><br />

Exposure<br />

Occupational 33.2 µg/dL in Pb-exposed<br />

group<br />

2.7 µg/dL in controls<br />

Occupational 10 Pb exposure workers vs.<br />

controls<br />

Worker BLLs <strong>of</strong> 41–50 µg/dL<br />

No controls >19 µg/dL<br />

Occupational Blood Pbs 64 µg/dL<br />

Range 21–90<br />

Table AX5-9.1 (cont’d). Studies on <strong>Lead</strong> Exposure and Immune Effects in Humans<br />

Dose or Blood <strong>Lead</strong><br />

Levels (BLLs) Sample Population Reported Effects Reference<br />

Occupational Comparison <strong>of</strong> workers with<br />

25–53 µg/dL vs. controls with<br />

8–17 µg/dL<br />

Environmental Near smelter BLLs varied<br />

seasonally 25–45 µg/dL<br />

Control area BLLs varied<br />

seasonally 10–22 µg/dL<br />

Occupational Workers (18–85.85.2 µg/dL<br />

BLL)<br />

controls (6.6–20.8 µg/dL BLL)<br />

Environmental 12 Afr.- American children<br />

BLLs 41–51µg/dL;<br />

7 controls BLLs 14–30 µg/dL<br />

10 Male workers in scrap metal<br />

refinery vs. 10 controls<br />

39 male workers in Pb exposed<br />

group<br />

PMN chemotaxis reduced to 2 different chemoattractants. Valentino<br />

et al. (1991)<br />

ConA-generated suppressor cell production—increased.<br />

Some other cellular parameters unchanged.<br />

Cohen et al.<br />

(1989)<br />

PHA response <strong>of</strong> lymphocytes from workers decreased. Alomran and<br />

Shleamoon<br />

(1988)<br />

Workers exposure to Pb No change in serum Ig levels PHA response <strong>of</strong> cells or NK activity. Kimber et al.<br />

(1986)<br />

Boys and girls ~11.5 yrs old living<br />

near Pb smelting plant<br />

Higher BLL associated with: decreased )-amino levulinic acid dehydrogetase.<br />

Decreased IgM and secretory IgA.<br />

Inversely related to IgG.<br />

73 workers vs. 53 controls Negative correlation <strong>of</strong> BLL and serum IgG and C3.<br />

Positive correlation <strong>of</strong> BLL and saliva IgA.<br />

12 African American preschool<br />

children vs. 7 controls<br />

Wagnerova<br />

et al. (1986)<br />

Ewers et al.<br />

(1982)<br />

No difference in anti-tetanus antibody levels or in complement levels. Reigart and<br />

Graber (1976)


AX5-150<br />

Table AX5-9.2. Effect <strong>of</strong> <strong>Lead</strong> on Antibody Forming Cells (In Vitro Stimulation)<br />

Species Strain/Gender Age Effect<br />

In Vivo/ Ex<br />

Vivo<br />

<strong>Lead</strong> Dose/<br />

Concentration<br />

Duration<br />

<strong>of</strong> Exposure Reference<br />

Mouse Various Adult ↑AFC No 10 µM 5 days McCabe and<br />

Lawrence (1991)<br />

Mouse Various Adult AFC No change Yes 10 mM in water 8 wks Mudziuski et al.<br />

(1986)<br />

Mouse CBA/J females Adult ↑AFC primary response No 100 µM 5 days Warner and<br />

Lawrence (1986)<br />

Mouse BDF1 females Adult ↑AFC—T dependent antigen<br />

AFC—T independent antigen, no<br />

change<br />

Mouse CBA/J females Adult ↑AFC Yes 0.08 mM and<br />

0.4 mM<br />

50 µg Pb acetate in water 3 wks Blakley and<br />

Archer (1981)<br />

4 wks Lawrence (1981a)<br />

Mouse CBA/J Adult ↑AFC No 10 −5 M 5 days Lawrence (1981b)<br />

Mouse CBA/J females Adult ↑AFC No 10 −4 M 1 hr preincubation Lawrence (1981c)<br />

Mouse Swiss males Adult ↓AFC Yes 0.5 ppm tetraethyl Pb 3 wks Blakley et al.<br />

(1980)<br />

Mouse Swiss Adult ↓AFC Yes 1300 ppm 10 wks Koller and Roan<br />

(1980)<br />

Rat SD Neonate–<br />

Juvenile<br />

Mouse Swiss Adult ↑AFC–IgM<br />

↓AFC–IgG<br />

Mouse Swiss Adult ↓AFC–IgM<br />

↓AFC–IgG<br />

↓AFC (IgM) Yes 25 ppm and 50 ppm 3 wks prenatal and<br />

6 wks postnatal<br />

Luster et al (1978)<br />

Yes 4 mg i.p. or oral Single dose Koller et al.<br />

(1976)<br />

Yes 13.75 ppm–1,375 ppm 8 wks Koller and<br />

Kovacic (1974)


AX5-151<br />

Table AX5-9.3. Studies Reporting <strong>Lead</strong>-induced Suppression <strong>of</strong> Delayed Type Hypersensitivity and Related Responses<br />

Species Age Strain/Gender Route Lowest Effective Dose<br />

Duration<br />

<strong>of</strong> Exposure Reference<br />

Rat Embryo SD females Oral to Dam 250 ppm (BLL at 4 wk = 6.75 µg/dL) 5 wks Chen et al. (2004)<br />

Chicken Embryo Cornell K females in ovo 200 µg Single injection E12 Lee et al. (2002)<br />

Rat Fetal CD females Oral to Dam 500 ppm 6 days Bunn et al.<br />

(2001c)<br />

Rat Embryo–fetal F344 and CD females Oral to Dam 250 ppm 3 wks Bunn et al.<br />

(2001b)<br />

Rat Embryo–fetal F344 females Oral to Dam 250 ppm (BLL = 34.8�µg/dL at birth) 3 wks Bunn et al.<br />

(2001a)<br />

Chicken Embryo Cornell K females in ovo 200 µg (BLL = 11 �µg/dL) Single injection E12 Lee et al. (2001)<br />

Mouse Adult BALB/c females Oral 512 ppm (BLL = 87� µg/dL) 3 wks McCabe et al.<br />

(1999)<br />

Rat Embryo-fetal F344 females Oral to Dam 250 ppm Pb acetate 5 wks (2 be<strong>for</strong>e, 3<br />

during gestation)<br />

Rat Embryo-fetal F344 females Oral to Dam 250 ppm Pb acetate 5 wks (2 be<strong>for</strong>e, 3<br />

during gestation)<br />

Chen et al. (1999)<br />

Miller et al.<br />

(1998)<br />

Goat Adult Females Gastric intubation 50 mg/kg Pb acetate 6 wks Haneef et al.<br />

(1995)<br />

Rat Adult Wistar males Oral 6.3 m mol kg -1 8 wks Kumar et al.<br />

(1994)<br />

Mouse Adult Swiss s.c. 0.5 mg/kg/d Shortest = 3 days<br />

just prior to<br />

challenge<br />

Laschi-Loquerie<br />

et al. (1984)<br />

Rat Neonatal/ Juvenile CD females Oral 25 ppm Pb acetate (BLL= 29.3 µg/dL) 6 wks Faith et al. (1979)<br />

Mouse Adult BALB/c i.p. 0.025 mg Pb acetate 30 days Muller et al.<br />

(1977)


AX5-152<br />

Species Strain/Gender Age<br />

Mouse C57Bl/6 and<br />

BALB/c<br />

Table AX5-9.4. Effect <strong>of</strong> <strong>Lead</strong> on Allogeneic and Syngeneic Mixed Lymphocyte Responses<br />

Proliferation<br />

Effects<br />

Rat Lewis males Adult ↑Allo-MLR<br />

↑Syngeneic-MLR<br />

In Vivo/<br />

Ex Vivo <strong>Lead</strong> Dose/Concentration<br />

Duration<br />

<strong>of</strong> Exposure References<br />

Adult ↑Allo-MLR No 0.1 µM 4 days McCabe et al. (2001)<br />

No 50 ppm Pb acetate 4 days Razani-Boroujerdi et al.<br />

(1999)<br />

Mouse CBA/J females Adult ↑Allo-MLR No 10 −6 –10 −4 M 5 days Lawrence (1981b)<br />

Mouse CBA/J females Adult ↑Allo-MLR Yes 0.08 mM and 0.4 mM 4 wks Lawrence (1981a)<br />

Mouse DBA/2J males Adult Allo-MLR no<br />

significant change<br />

Yes 13, 130 and 1300 ppm 10 wks Koller and Roan (1980)


AX5-153<br />

Table AX5-9.5. Effect <strong>of</strong> <strong>Lead</strong> on Mitogen-induced Lymphoid Proliferation<br />

Species Strain/ Gender Age Proliferation Effects<br />

In Vivo/<br />

Ex Vivo <strong>Lead</strong> Dose/ Concentration<br />

Duration<br />

<strong>of</strong> Exposure References<br />

Human C Adult ↓PHA Yes Not available Occupational Mishra et al. (2003)<br />

Mouse TO males Adult ↓ConA<br />

↓LPS<br />

Mouse Several Adult PHA stimulation No<br />

change<br />

Rat Lewis and F344<br />

males<br />

Adult ↑ConA<br />

↑LPS<br />

Yes 1 mg/kg daily 2 wks Fernandez–Carbezudo et al.<br />

(2003)<br />

No 25 µM 3 days McCabe et al. (2001)<br />

No 25 ppm 3 days Razani–Boroujerdi et al. (1999)<br />

Mouse CBA/J Adult LPS No change No 10 µM 3 days McCabe and Lawrence (1990)<br />

Rat AP strain males Adult PHA No change Yes 100 ppm and 1,000 ppm 2–20 wks Kimber et al. (1986)<br />

Mouse CBA/J females Adult ConA<br />

LPS<br />

No change<br />

Mouse BDF1 females Adult ↑ConA<br />

↑PHA<br />

↑Staph A enterotoxin<br />

LPS no change<br />

Rat SD males Adult ↑ConA<br />

↑PHA<br />

↑LPS<br />

Mouse CBA/J females Adult PHA no change<br />

↓LPS (high doses only)<br />

Mouse CBA/J females Adult ConA, PHA no change<br />

↑LPS<br />

Mouse CBA/J females Adult ConA, PHA no change<br />

↑LPS<br />

No 10 −4 M 2 days Warner and Lawrence (1986)<br />

Yes 0–1,000 ppm 3 wks Blakley and Archer (1982)<br />

Yes 1% Pb acetate in diet 2 wks Bendich et al. (1981)<br />

Yes 10 mM 4 wks Lawrence (1981a)<br />

No 10 −6 –10 −4 M 2.5 days Lawrence (1981b)<br />

No 10 −6 –10 −4 M 2–5 days Lawrence (1981c)


AX5-154<br />

Table AX5-9.5 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> on Mitogen-induced Lymphoid Proliferation<br />

Species Strain/ Gender Age Proliferation Effects<br />

Mouse C57 Bl/6 males Adult ↓PHA<br />

Rat SD females Neonatal–<br />

Juveniles<br />

↓ConA<br />

LPS No change<br />

↓PHA<br />

↓ConA<br />

In Vivo/<br />

Ex Vivo <strong>Lead</strong> Dose/ Concentration<br />

Duration<br />

<strong>of</strong> Exposure References<br />

Yes 1,300 ppm 8 wks Neilan et al. (1980)<br />

Yes 25 ppm 6 wks Faith et al. (1979)<br />

Mouse BALB/c Adult ↑LPS No 10 −5 –10 −3 M 3 days Gallagher et al. (1979)<br />

Mouse Swiss males Adult ↓PHA<br />

↓PWM<br />

Mouse Swiss males Adult ↑PHA<br />

↑PWM<br />

Yes 2,000 ppm 30 days Gaworski and Sharma (1978)<br />

No 0.1 mM–1.0 mM 2–3 days Gaworski and Sharma<br />

(1978)<br />

Mouse CBA/J Adult ↑LPS Yes 13 ppm 18 mo Koller et al. (1977)<br />

Mouse BALB/c Adult ↑LPS No 10 −5 –10 −3 M 2–3 days Shenker et al. (1977)


AX5-155<br />

Species<br />

Nitric Oxide<br />

Table AX5.9.6. Pattern <strong>of</strong> <strong>Lead</strong>-induced Macrophage Immunotoxicity<br />

Strain/<br />

Gender Age Function<br />

In Vivo/<br />

Ex Vivo<br />

Lowest Effective<br />

Dose<br />

Duration<br />

<strong>of</strong> Exposure References<br />

Human Both genders Juvenile ↓NO Yes NK Pineda-Zavaleta et al.<br />

(2004)<br />

Rat CD males Embryo ↓NO Yes 500 ppm 6 days Bunn et al. (2001c)<br />

Chicken Cornell K<br />

strain females<br />

Mouse BALB/c<br />

females<br />

Chicken HD-11 cell<br />

line<br />

Mouse CBA/J<br />

females<br />

Mouse CBA/J<br />

females<br />

Reactive Oxygen Intermediates<br />

Human Associated in<br />

males<br />

Embryo ↓NO Yes 10 µg One injection<br />

(E5)<br />

Adult ↓NO No 20 µg/mL<br />

one lower dose ↑NO<br />

Lee et al. (2001)<br />

2 hrs Krocova et al. (2000)<br />

- ↓NO No 4.5 µg 18 hrs Chen et al. (1997b)<br />

Adult ↓NO No 1.0 µg 4 days Tian and Lawrence (1996)<br />

Adult ↓NO No 0.625 µM 4 days Tian and Lawrence (1995)<br />

Juvenile ↑ROI Yes NK NK Pineda-Zavaleta et al.<br />

(2004)<br />

Rat Not indicated NK ↑ROI No 240 µM 3 hrs Shabani and Rabbani<br />

(2000)<br />

Mouse BALB/c<br />

females<br />

Rabbit New Zealand<br />

white males<br />

Adult ↑ROI Yes 1.5 mg/kg diet 30 days Baykov et al. (1996)<br />

Adult ↑ROI Yes 31 µg/m 3 inhaled 3 days Zelik<strong>of</strong>f et al. (1993)


ANNEX TABLES AX5-10<br />

AX5-156


AX5-157<br />

Table AX5-10.1. Hepatic Drug Metabolism<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Triethyl Pb<br />

chloride, 0–3.0<br />

mg/kg b. wt.<br />

In vitro, 0.0–3.0<br />

mM triethyl Pb<br />

5 or 10 µmol/100g<br />

b. wt. Pb nitrate;<br />

i.v.<br />

5, 10, 50 mg Pb<br />

acetate kg !1 b. wt.<br />

100 µmol/kg; i.v.<br />

Pb acetate<br />

100 µmol/kg<br />

Pb nitrate; i.v.<br />

100 µmol/kg; i.v.<br />

Pb acetate<br />

100 µmoles /kg;<br />

i.v.<br />

2 days In vitro, rat<br />

microsomes<br />

Not specified In vivo, rat<br />

microsomes<br />

36 h Male Fischer<br />

344 rats<br />

Multiple<br />

durations<br />

(15 days,<br />

2 and 3 mo)<br />

Female albino<br />

rats<br />

24 h Male Fischer<br />

344 rats<br />

9 h be<strong>for</strong>e or 6 h<br />

after<br />

2-methoxy-4aminoazobenzene<br />

(2-Meo-AAB)<br />

Male Fischer<br />

344 rats<br />

—<br />

—<br />

Triethyl Pb increased microsomal N-oxygenation in vivo and<br />

decreased microsomal C oxygenation by in vitro treatment. Either<br />

treatment thus gave rise to an increase in the N-oxygenation/Coxygenation<br />

ratio, which may lead to tumor potentiation.<br />

— Pb decreases phase I components (liver microsomal cyt.P-450), and<br />

increases Phase <strong>II</strong> components (GST, DT diaphorase etc). Liver<br />

cytosol in treated animals had a polypeptide that cross-reacted with<br />

GSTP.<br />

— Over all induction <strong>of</strong> cyt-p—450 and b5 in liver, long-term increase<br />

in liver GST and GSH.<br />

— Decrease in total CYP amount, selective inhibition <strong>of</strong> CYP1A2 and<br />

decrease in the expression at m-RNA and protein level, induction <strong>of</strong><br />

placental <strong>for</strong>m <strong>of</strong> glutathione s-transferase (GST-P).<br />

— Male fisher rats treated with different metal ions CPb nitrate, nickel<br />

chloride, cobalt chloride or cadmium chloride exhibited decreased<br />

total CYP amount in liver microsomes. However, only Pb reduced<br />

the levels <strong>of</strong> the mRNA and protein <strong>of</strong> CYP 1A2 induced with 2methoxy-4-aminoazobenzene<br />

(2-Meo-AAB) and decreased the<br />

microsomal activity (Per CYP), Pb also induced placental <strong>for</strong>m <strong>of</strong><br />

Glutathione, a marker enzyme <strong>for</strong> preneoplastic lesion.<br />

24 h Male F 344 rats — Inhibition <strong>of</strong> CYP1A mRNA(s) by Pb nitrate is by aromatic amines,<br />

not by aryl hydrocarbons.<br />

Multiple<br />

durations (3, 6,<br />

12, 24, and 36 h)<br />

Male Wistar<br />

rats<br />

— Stimulation <strong>of</strong> TNFα preceding hepatocyte DNA synthesis<br />

indicates a role <strong>for</strong> it in liver cell proliferation.<br />

Pb nitrate enhances sensitivity to bacterial LPS, in hepatocytes.<br />

Odenbro and<br />

Arhenius (1984)<br />

Roomi et al.<br />

(1986)<br />

Nehru and<br />

Kaushal (1992)<br />

Degawa et al.<br />

(1994)<br />

Degawa et al.<br />

(1995)<br />

Degawa et al.<br />

(1996)<br />

Shinozuka et al.<br />

(1994)


AX5-158<br />

Table AX5-10.1 (cont’d). Hepatic Drug Metabolism<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Single 0.33 mg/kg-<br />

1 Pb nitrate<br />

Pb acetate, 75 mg<br />

<strong>of</strong> Pb 2+ /kg,<br />

intraperitonial<br />

Multiple<br />

durations<br />

Multiple analyses<br />

up to 30 h<br />

Male Wistar rats — Pb confers protection against the CCL4 induced hepatotoxicity as<br />

evident by marked reduction in serum Alanine aminotransferase<br />

(AST) and aspartate aminotransferase (AST) and this protection is<br />

not associated with the mitotic response <strong>of</strong> Pb.<br />

C57BL/6 male<br />

mice<br />

0–10 !6 M Pb nitrate 3 days Fish hepatoma<br />

cell line<br />

PLHC-1<br />

DT Diaphorase<br />

activity 0–125<br />

mg/kg Pb acetate,<br />

Pb nitrate<br />

Time course<br />

experiments<br />

100 mg/kg Pb<br />

acetate, i.p.<br />

Cell viability<br />

assays 0–30 µM,<br />

<strong>for</strong> all other As ,<br />

Pb, Hg, 5 µM, Cd,<br />

1 µM<br />

— The decrease in P-450 as a result <strong>of</strong> Pb poisoning occurs at two<br />

levels. (1) A mechanism unrelated to heme, where Pb interferes<br />

with P-450 in 2 ways. (2) A mechanism dependent on heme, in<br />

which Pb inhibits heme synthesis.<br />

— Effect <strong>of</strong> heavy metals Cu(<strong>II</strong>), Cd(<strong>II</strong>), Co(<strong>II</strong>), Ni(<strong>II</strong>), Pb(<strong>II</strong>), and<br />

Zn(<strong>II</strong>), on Cytochrome induction (CYP1A) induction response and<br />

Ethoxy resorufin-o-deethylase (EROD) activity.<br />

All metals had a more pronounced effect on EROD activity than<br />

Cyp1 A protein. The rank order <strong>of</strong> the metal inhibition on EROD is<br />

Cd(<strong>II</strong>) > Ni(<strong>II</strong>) > Cu(<strong>II</strong>) > Co(<strong>II</strong>) = Zn(<strong>II</strong>), Pb(<strong>II</strong>), Cd(<strong>II</strong>) and (Cu).<br />

May affect Cyp1 A system <strong>of</strong> the fish liver at low concentrations<br />

through the direct inhibition <strong>of</strong> CYP 1A enzyme activity.<br />

24 h–120 h Male Wistar rats — Pb acetate and nitrate induce DT diaphorase activity which is<br />

inhibited significantly by Dil a calcium antagonist, showing that<br />

these changes are mediated by intracellular calcium changes. Pb<br />

acetate induces DT diaphorase activity with out thymus atrophy and<br />

hence was suggested to be a mon<strong>of</strong>unctional inducer as against the<br />

Methyl cholanthrene induced DT diaphorase activity.<br />

24 h in general<br />

and <strong>for</strong> EROD<br />

assays by PAHs<br />

24–72 h<br />

Primary human<br />

hepatocytes<br />

— The effect <strong>of</strong> metals on PAH induced CYP1A and 1A2 as probed<br />

by Ethoxy resorufin o- deethylase activity has demonstrated, metals<br />

-Arsenic, Pb, mercury and cadmium decreased CYP1A1/ A2<br />

expression by polycyclic aromatic hydrocarbons depending on the<br />

dose, metal and the PAH. Arsenic was most effective, followed by<br />

Pb, cadmium, and mercury. Cell viability was decreased by 20–<br />

28% by metals.<br />

Calabrese et al.<br />

(1995)<br />

Jover (1996)<br />

Bruschweiler<br />

et al. (1996)<br />

Arizono et al.<br />

(1996)<br />

Vakharia (2001)


AX5-159<br />

Table AX5-10.1 (cont’d). Hepatic Drug Metabolism<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

10–100 µM,<br />

in vitro<br />

5 and 10<br />

µmoles/100 g <strong>of</strong><br />

b.wt, single i.p<br />

100 µmoles/100 g<br />

b. wt. Pb nitrate,<br />

single injection, i.v.<br />

100 mg/kg i.p.,<br />

single exposure<br />

100 µmol/kg body<br />

wt, i.v<br />

100 µmol/kg b. wt.,<br />

intra cardiac<br />

10 µmol/100g b.<br />

wt., Pb nitrate, i.v.<br />

single dose<br />

24 h Murine<br />

hepatoma cell<br />

line<br />

Animals were<br />

sacrificed at<br />

1, 2, 3, 4, and<br />

15 days<br />

— Effect <strong>of</strong> heavy metals on Aryl hydrocarbon regulated genes—<br />

metals alone did not induce a significant change in the cyp1a1<br />

activity and protein levels but increased its m-RNA expression.<br />

AHR ligand-mediated induction <strong>of</strong> cyp1a1 activity and protein was<br />

observed by all the metals. Pre and post translational modulation in<br />

this regulation have been implicated. These results demonstrate<br />

that the heavy metals differentially modulate the constitutive and<br />

the inducible expression <strong>of</strong> AHR regulated genes.<br />

— Wistar Rat — Pb nitrate induced the expression <strong>of</strong> Placental <strong>for</strong>m <strong>of</strong> Glutathione<br />

transferase along with liver cell proliferation. The biochemical<br />

lesions induced by Pb under these conditions were similar to that <strong>of</strong><br />

hepatic nodules.<br />

Multiple analyses<br />

0–96 h<br />

Wistar rats — Acute Pb treatment results in induced activity <strong>of</strong> Gamma-glutamyl<br />

transpeptidase, induced GSTP, a typical marker <strong>of</strong> pre neoplastic<br />

lesion in most hepatocytes. Pb also inhibited liver adenylate<br />

cyclase activity 24 h postexposure.<br />

Male DDY<br />

strain mice<br />

70 h Male Sprague<br />

Dawley rats<br />

Multiple time<br />

point analyses<br />

starting 6 days to<br />

5 mo<br />

Analyses at<br />

multiple time<br />

points 0–10 days<br />

Male and<br />

female Wistar<br />

rats<br />

Male Fischer<br />

344 young adult<br />

rats<br />

— Pb decreased Glutathione content and decreased Glutathione stransferase<br />

activity that is independent <strong>of</strong> Glutathione levels.<br />

— Acute Pb nitrate treatment caused a significant increase <strong>of</strong> GST<br />

activity in liver and kidney. While in liver the activity increase is<br />

mainly due to isozyme GST 7-7, in kidney it is through the<br />

induction <strong>of</strong> all the isozymes.<br />

— Intracardiac administration <strong>of</strong> Pb acetate results in elevation <strong>of</strong><br />

glutathione transferase (GST) in Kupffer cells, the early response to<br />

GST.Yp was observed in sinusoidal cells and had a later patchy<br />

response in the expression <strong>of</strong> GST.Yp Yp in hepatocytes<br />

— Glutathione transferase P1-1 is induced significantly by a single<br />

intravenous dose <strong>of</strong> Pb nitrate through increased transcription and<br />

modulations at post transcription and translational levels.<br />

Korashy and<br />

El-Kadi (2004)<br />

Roomi et al.<br />

(1987)<br />

Columbano et al.<br />

(1988)<br />

Nakagawa et al.<br />

(1991)<br />

Planas-Bhone and<br />

Elizalde (1992)<br />

Boyce and Mantel<br />

(1993)<br />

Koo et al. (1994)


AX5-160<br />

Table AX5-10.1 (cont’d). Hepatic Drug Metabolism<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Pb nitrate,<br />

100 µm/kg i.p,<br />

3 times every 24 h<br />

Pb acetate<br />

100 µM/kg.<br />

10 nM Pb nitrate 24 h be<strong>for</strong>e<br />

transfection with<br />

ECAT deletion<br />

mutant, every 24<br />

h there after till<br />

48 h after<br />

transfection<br />

10 mg Triethyl Pb,<br />

i.p. single dose<br />

114 mg Pb<br />

acetate/kg b. wt. i.p<br />

A. 1.5–3.0 mg/kg<br />

wt<br />

Triethyl Pb (TEL)<br />

i.p.<br />

B. 0.05–0.5, TEL<br />

to liver microsomal<br />

fractions<br />

48 h Transgenic rats<br />

with 5 different<br />

constructs<br />

—<br />

0.5–24 h<br />

having GST-P<br />

and/or<br />

chloromphenica<br />

l acetyl<br />

transferase<br />

coding<br />

sequence.<br />

—<br />

Analyses at<br />

multiple durations<br />

(3, 4, 7, 10, or 14<br />

days)<br />

Single (0.5–12 h<br />

group) or multiple<br />

(72 h and 7 days<br />

group) exposure<br />

2 exposures <strong>for</strong><br />

48 h<br />

30 min<br />

incubations<br />

NRK Kidney<br />

fibroblasts<br />

GSTP (placental GST), is regulated by Pb at transcriptional level.<br />

GST-P enhancer (GPEI), is an essential cis-element required <strong>for</strong> the<br />

activation <strong>of</strong> the GST-P gene by Pb and is involved in the activation<br />

regardless <strong>of</strong> the trans-activators involved. GPEI element consists<br />

<strong>of</strong> two AP-1 binding sites. Activation <strong>of</strong> GST-P gene by Pb is<br />

mediated in major part by enhancer GPEI, which may involve AP-1<br />

activation partially.<br />

— Pb induces GST-P in NRK normal rat kidney fibroblast cell line.<br />

Fischer 344 rats — Decreased liver Glutathione s-transferase (GST) activity and lower<br />

levels <strong>of</strong> several hepatic GST.<br />

Increase in quinone reductase activity by day 14 in liver.<br />

Sprague Dawley — Pb exposure resulted in hepatic Glutathione (GSH) depletion and<br />

increased malondialdehyde (MDA) production.<br />

Female Wistar — Pretreatment <strong>of</strong> rats did not affect the liver microsomal Oestradiol-<br />

17β metabolism or the content <strong>of</strong> cytochrome P-450 and<br />

cytochrome b5.<br />

Liver<br />

microsomes<br />

from female<br />

Wistar rats<br />

— TEL at 0.05 mM significantly reduced 17β-hydroxy steroid<br />

oxidation and at concentration <strong>of</strong> 0.05 mM decreased 16αhydroxylation.<br />

Suzuki et al.<br />

(1996)<br />

Daggett et al.<br />

(1997)<br />

Daggett et al.<br />

(1998)<br />

Odenbro and<br />

Rafter (1988)


AX5-161<br />

Table AX5-10.1 (cont’d). Hepatic Drug Metabolism<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

50 mg/kg,<br />

intragastric<br />

Abbreviations<br />

b. wt.—body weight<br />

a CYP—Cytochrome P-450<br />

GSH—Glutathione<br />

GSSG—Oxidized glutathione<br />

TEL—Triethyl lead<br />

CCL—Carbon tetrachloride<br />

GSTP—Placental glutathione transferase<br />

MDA—Malondialdehyde<br />

Cu—Copper<br />

Cd—Cadmium<br />

Al—Aluminum<br />

Zn—Zinc<br />

Pb—<strong>Lead</strong><br />

Ni—Nickel<br />

TNFα—Tumor necrosis factor<br />

ALA—Alanine aminotransferase<br />

PAH—Polycyclic aromatic hydrocarbons<br />

LPS—Lipopolysaccharides<br />

8 wks Male Albino<br />

Wistar rats<br />

— Accentuation <strong>of</strong> liver membrane lipid peroxidation. significant<br />

inhibition <strong>of</strong> liver antioxidant enzymes. Reduced ratio <strong>of</strong> reduced<br />

glutathione(GSH) to oxidized glutathione (GSSG),<br />

Sandhir and Gill<br />

(1995)


AX5-162<br />

Table AX5-10.2. Biochemical and Molecular Perturbations in <strong>Lead</strong>-induced Liver Tissue<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Pb-diethyl<br />

dithiocarbomate<br />

complex, Pb (DTC) 2,<br />

or Pb acetate 0.033–<br />

10 µM<br />

0.5–20 h Primary hepatocytes — Effect <strong>of</strong> interactions between Pb and diethyl dithiocarbomate (DTC) on the<br />

enzyme δ amino levulinic acid dehydratase in primary hepatocytes.<br />

Lipophilic Pb (DTC)2 caused a more rapid and stronger inhibition <strong>of</strong> ALAD<br />

activity than Pb acetate. Pb uptake is higher and more rapid with Pb (DTC)<br />

2 than Pb acetate. This increased inhibition <strong>of</strong> ALAD activity by Pb (DTC)<br />

2 might be due to facilitated cellular transport in the complexed <strong>for</strong>m<br />

resulting in higher cellular concentrations <strong>of</strong> Pb.<br />

— — Primary rat<br />

hepatocytes<br />

— DTC decreases cellular effects <strong>of</strong> Pb and Cd despite unchanged/ even<br />

slightly increased concentrations <strong>of</strong> the metals. Hepatic ALAD was<br />

significantly inhibited in cells treated with Pb Ac and Pb (DTC)2.<br />

— — DBA and C57 mice — DBA mice(with a duplication <strong>of</strong> the ALAD gene accumulated twice the<br />

amount <strong>of</strong> Pb in their blood and had higher Pb levels in liver and kidney<br />

than mice with the single copy <strong>of</strong> the gene (C57), exposed to the same oral<br />

doses <strong>of</strong> the Pb during adult hood. Blood Zinc protoporphyrin (ZPP)<br />

increased with Pb exposure in C57 mice and were not affected in DBA<br />

mice.<br />

100 µmol/kg b. wt.<br />

i.v. single dose<br />

Pb nitrate, Single dose<br />

100 µmol/kg b. wt.<br />

Single dose,<br />

analyses per<strong>for</strong>med<br />

12, 24, 48, 72, 96<br />

and 168 h<br />

Male Wistar Albino<br />

Rats<br />

— First in vivo report showing association between Pb induced liver<br />

hyperplasia, Glucose-6-phosphate levels, and cholesterol synthesis.<br />

Pb treatment increased hepatic de novo synthesis <strong>of</strong> cholesterol as evident<br />

by increased cholesterol esters and increase <strong>of</strong> G-6-PD to possibly supply<br />

the reduced equivalents <strong>for</strong> de novo synthesis <strong>of</strong> cholesterol. Changes in<br />

these biochemical parameters were accompanied by liver hyperplasia.<br />

0–168 h Male Wistar rats — Pb nitrate induces hepatic cell proliferation followed by reabsorption <strong>of</strong><br />

excess tissue with in 10–14 days. The proliferation was correlated with<br />

hepatic denovo synthesis <strong>of</strong> cholesterol, stimulation <strong>of</strong> hexose<br />

monophosphate shunt pathway and alterations in serum lipo proteins.<br />

Pb nitrate — Wistar rats — Pb nitrate induces multiple molecular <strong>for</strong>ms <strong>of</strong> Glucose-6- phosphate<br />

dehydrogenase with an increase <strong>of</strong> band 3 and a concomitant increase <strong>of</strong><br />

band 1, shifting from the pattern induced by fasting with an increase in<br />

band 1.<br />

Oskarsson and<br />

Hellström-Lindahl<br />

(1989)<br />

Hellström-Lindahl<br />

and Oskarsson<br />

(1990)<br />

Claudio et al.<br />

(1997)<br />

Dessi et al. (1984)<br />

Pani et al. (1984)<br />

Batetta et al. (1990)


AX5-163<br />

Table AX5-10.2 (cont’d). Biochemical and Molecular Perturbations in <strong>Lead</strong>-induced Liver Tissue<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Pb nitrate, single i.v.<br />

10 µM/100 g b. wt.<br />

Multiple time points<br />

24–72 h and<br />

20 days<br />

Male Wistar rats — Pb nitrate exposure results in complete loss <strong>of</strong> liver glycogen between 24<br />

and 48 h, which was replenished and was found in excess in treated liver<br />

hepatocytes by 20 days. Glycogen synthase and glycogen phosphorylase<br />

activities were diminished by 24 h and return to normal values by day 20.<br />

The pentose phosphate enzymes were upregulated, which coincided highly<br />

with the increase in mitotic rate. Overall Pb nitrate induces drastic<br />

alterations in hepatic carbohydrate metabolism along with increased hepatic<br />

cell proliferation.<br />

— — Rats — Pb acetate induced mitotic response much more effectively in renal<br />

epithelial cells than liver cells (675 fold less).<br />

10 or 20 mg/kg as Pb<br />

acetate, subcutaneous<br />

100 µM/kg b. wt Pb<br />

nitrate, i.v<br />

2000 ppm Pb acetate<br />

in diet.<br />

0–4000 ppm<br />

Pb acetate, oral<br />

Once a wk <strong>for</strong><br />

5 wks<br />

Occupationally<br />

exposed workers<br />

Rats<br />

36 h postexposure Male Wistar Albino<br />

rats<br />

3 wks Arbor Acres male<br />

chicks<br />

21 days Arbor Acre broiler<br />

chicks<br />

Pb-exposed<br />

workers:<br />

0.24–30 nM/mL<br />

Control rats:<br />

0.18 nM/mL<br />

10 mg Pb/kg:<br />

2.42 nM/mL:<br />

20 mg Pb/kg:<br />

3.82 nM/mL<br />

Pb induces lipid peroxidation in serum <strong>of</strong> manual workers, while blood<br />

superoxide dismutase (SOD) activity decreased. Similar phenomenon was<br />

observed with rats that were subcutaneously injected with Pb acetate.<br />

At higher than 20 µM concentration, Pb in untreated microsomes increased<br />

NADPH dependent lipid peroxidation.<br />

— Endogenous source <strong>of</strong> newly synthesized cholesterol together with increase<br />

<strong>of</strong> HMP shunt enzyme activities is essential <strong>for</strong> hepatic cell proliferation by<br />

Pb nitrate.<br />

— Liver non protein sulphahydryl (NPSH) and glutathione (GSH) were<br />

increased upon Pb exposure. The concentrations <strong>of</strong> liver glutamate, glycine,<br />

and methionine were also elevated upon Pb exposure.<br />

— Pb increases tissue peroxidation via a relative increase <strong>of</strong> 20:4 fatty acids.<br />

Decrease in the hepatic ratio <strong>of</strong> 18:2/20:4 might be specific to Pb toxicity.<br />

Hacker et al. (1990)<br />

Calabrese and<br />

Baldwin et al.<br />

(1992)<br />

Ito et al. (1985)<br />

Dessi et al. (1990)<br />

Mc Gowan and<br />

Donaldson et al.<br />

(1987)<br />

Donald and<br />

Leeming (1984)


AX5-164<br />

Table AX5-10.2 (cont’d). Biochemical and Molecular Perturbations in <strong>Lead</strong>-induced Liver Tissue<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Sodium vanadate,<br />

30 mg/kg<br />

subcutaneous in mice<br />

30 mg/kg b.wt, i.p. in<br />

rats<br />

0.5 mM<br />

Vanadium sulphate in<br />

drinking water <strong>for</strong><br />

chronic treatment<br />

250–2000 ppm Pb<br />

acetate in diet<br />

1.25–20.00 mg/L Pb<br />

nitrate, oral<br />

250 mg/L <strong>of</strong> Pb as Pb<br />

acetate, oral<br />

35–70 mg, Pb intra<br />

gastric<br />

Abbreviations<br />

Acute studies,<br />

24 h<br />

Chronic studies<br />

10 wks<br />

Male Swiss-<br />

Webster mice<br />

Male Sprague<br />

Dawley Rat<br />

19 days Arbor Acre broiler<br />

chicks<br />

—<br />

—<br />

Sodium orthovandate increases lipid peroxidation in kidneys <strong>of</strong> mice and<br />

rats. Malondialdehyde (MDA) <strong>for</strong>mation increased 100%, with in 1 h<br />

after injection.<br />

In both rat and mice, no significant increase in lipid peroxidation was<br />

observed in brain, heart, lung, and spleen.<br />

Chronic exposure to vanadium, through maternal milk and drinking water<br />

<strong>for</strong> 10 wks increased MDA <strong>for</strong>mation and lipid peroxidation in kidneys.<br />

— Dietary Pb consistently increased liver arachidonic acid, the<br />

arachidonate/linoleate ratio and hepatic non-protein sulfhydryl<br />

concentration. Hepatic microsomal fatty acid elongation activity was<br />

decreased by Pb over all. These results demonstrate that changes in the<br />

precursors and mechanisms involved with eicosanoid metabolism are not<br />

always reflected in tissue concentrations <strong>of</strong> leukotriens and prostaglandin.<br />

30 days Fresh water fish — Pb accumulation in the liver and other tissue increased in a dose dependent<br />

manner up to 5mg/L, exposure to sublethal concentration (5 ppm) <strong>of</strong> Pb<br />

reduced the total lipids, phospholipids, and cholesterol levels in the liver<br />

and ovary. Pb nitrate may affect the fecundity <strong>of</strong> fish by altered lipid<br />

metabolism.<br />

5 wks <strong>of</strong> exposure<br />

followed by 4 wks<br />

<strong>of</strong> recovery<br />

One or two times a<br />

wk/7 wks<br />

a CYP—Cytochrome P-450<br />

ALAD—Aminolevulinic acid dehydratas<br />

GSH—Reduced Glutathione<br />

Weanling female<br />

SD rats<br />

Male Buffalo rats Control: 4.6 µg/dL<br />

Pb 35 mg/kg:<br />

16.8 µg/dL<br />

Pb 70 mg/kg:<br />

32.4 µg/dL<br />

— Effect <strong>of</strong> weight loss on body burden <strong>of</strong> Pb: weight loss increases the<br />

quantity and concentration <strong>of</strong> Pb in the liver even in the absence <strong>of</strong><br />

continued exposure.<br />

ZPP—Zinc protoporphyrin<br />

HMP—Hexose monophosphate shunt pathway<br />

b. wt.—body weight<br />

Decrease in plasma cholesterol, and HDL fraction, increase in serum<br />

triglyceride, atrophy <strong>of</strong> the elastic fibers in the aorta.<br />

Donaldson et al.<br />

(1985)<br />

Knowles and<br />

Donaldson et al.<br />

(1990)<br />

Tulasi et al. (1992)<br />

Han et al. (1996)<br />

Skoczynska et al.<br />

(1993)


AX5-165<br />

Table AX5-10.3. Effect <strong>of</strong> <strong>Lead</strong> Exposure on Hepatic Cholesterol Metabolism<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

100 µmol/kg body wt,<br />

i.v. Pb nitrate<br />

100 µmol/kg body wt,<br />

i.v. Pb nitrate<br />

0.05 mg/kg body<br />

wt/d. Pb acetate,<br />

subcutaneous, with or<br />

without cadmium<br />

acetate 0.025 mg Pb<br />

acetate/kg body wt/d<br />

300 mg/L Pb acetate,<br />

oral<br />

a CYP—Cytochrome P-450<br />

b wt.—body weight<br />

Multiple durations<br />

0, 3, 6, 12, 24, and<br />

48 h<br />

Multiple durations<br />

0, 1, 3, 6, 12, 18, 24,<br />

48, and 72 h<br />

Preexposure <strong>for</strong><br />

5–7 days, gestation<br />

through lactation<br />

Gestation through<br />

lactation analyses<br />

done at day 12 and<br />

day 21 postnatal<br />

Male Sprague<br />

Dwaley (SD) rats<br />

Male Sprague<br />

Dawley (SD) rats<br />

Female Charles<br />

Foster rats<br />

Female Wistar<br />

rats<br />

— Pb nitrate, activates the expression <strong>of</strong> the SREBP-2 and CYP 51 gene<br />

with out decreasing the serum cholesterol level.<br />

— Pb nitrate effects on hepatic enzymes involved in cholesterol homeostasis.<br />

Demonstrated <strong>for</strong> the first time sterol independent gene regulation <strong>of</strong><br />

cholesterol synthesis in Pb nitrate treatment.<br />

— Pb and cadmium accumulated in the livers <strong>of</strong> metal treated pregnant and<br />

lactating rats. Hepatic steroid metabolizing enzyme 17-β-hydroxy steroid<br />

oxidoreductase and UDP glucaronyl transferase were decreased and the<br />

hepatic Cytochrome P-450 content was reduced by the metal exposure.<br />

Pb and cadmium alter liver biochemical parameters, however, combined<br />

exposure had no intensifying effect on liver parameters. When<br />

administered together on similar concentration basis, the major effects<br />

are mediated by cadmium.<br />

Control: 1.13 µg/dL<br />

Pb-exposed<br />

12 days PN: 22.01<br />

µg/dL<br />

21d PN: 22.77 µg/dL<br />

In neonates, decrease in liver Hb, iron, alkaline and acid phosphatase<br />

levels. Protein, DNA and lipid total amounts were reduced and hepatic<br />

glycogen content was reduced. Pb intoxication <strong>of</strong> mothers in gestation<br />

and lactation results in alterations in the hepatic system in neonates<br />

and pups.<br />

Kojima et al. (2002)<br />

Kojima et al. (2004)<br />

Pillai and Gupta<br />

(2004)<br />

Corpas et al.<br />

(2002b)


AX5-166<br />

Table AX5-10.4. <strong>Lead</strong>, Oxidative Stress, and Chelation Therapy<br />

Concentration and<br />

Compound Duration Species Blood <strong>Lead</strong> Effects Reference<br />

Pb acetate, 50 mg/kg<br />

b.wt, intragastric<br />

2,000 ppm, Pb<br />

acetate, Diet<br />

8 wks Male Albino<br />

Wistar rats<br />

5 wks Male Fisher 344<br />

rats, young and<br />

old<br />

Young control:<br />


AX5-167<br />

Table AX5-10.4 (cont’d). <strong>Lead</strong>, Oxidative Stress, and Chelation Therapy<br />

Concentration and<br />

Compound Duration Species Blood <strong>Lead</strong> Effects Reference<br />

550 ppm Pb acetate,<br />

oral DMSA treatment.<br />

Pb acetate Dose to<br />

achieve blood Pb<br />

levels <strong>of</strong> 35–<br />

40 µg/dL.<br />

Biweekly dose<br />

adjustments, oral<br />

followed by treatment<br />

with chelator.<br />

5 mg Pb kg−1, i.p Pb<br />

acetate followed by<br />

chelators <strong>for</strong> various<br />

time points.<br />

50 mg/kg Pb as Pb<br />

nitrate, i.p, two<br />

injections, 16h apart<br />

50% Ethanol, 0.5 mL,<br />

two injections, 16 h<br />

apart<br />

0.1% Pb acetate in<br />

drinking water with<br />

and without Sodium<br />

Molybdate, i.p<br />

(A) Pb <strong>for</strong> 35 +<br />

21 days<br />

(B) Pb 35 days and<br />

Pb and DMSA<br />

<strong>for</strong> 21 days<br />

(C) Pb 35 days and<br />

DMSA <strong>for</strong><br />

21 days<br />

(D) Acedified Di H2O<br />

<strong>for</strong> 35 days and<br />

Di water <strong>for</strong><br />

21 days<br />

1 yr, chelator <strong>for</strong><br />

two successive<br />

19 day period<br />

following Pb<br />

exposure.<br />

6–7 Wk old male<br />

Sprague-Dawley<br />

rats<br />

Infant rhesus<br />

monkeys<br />

Analyses at Day 5 Suckling Wistar<br />

rats<br />

Pb-exposed:<br />

50 µg/dL<br />

Pb 35 days: Ranged<br />

from 5–20 µg/dL +<br />

DMSA from 0–<br />

240 µg/kg/d<br />

Pb-exposed:<br />

35–40 µg/dL<br />

DMSA reversed the hematological effects <strong>of</strong> Pb, decreased the blood,<br />

brain , bone, kidney and liver concentration and produced marked Pb<br />

diuresis, even when challenged with ongoing Pb exposure.<br />

Specific emphasis on the beneficial effects <strong>of</strong> succimer treatment to<br />

cessation <strong>of</strong> Pb exposure. These data demonstrated that succimer<br />

efficiently reduces blood Pb levels which does not persist beyond the<br />

completion <strong>of</strong> treatment. They also demonstrate the relative benefit <strong>of</strong><br />

eliminating Pb exposures , which serves to underscore the importance <strong>of</strong><br />

primary prevention <strong>of</strong> Pb exposure. Neither DMSA treatment nor the<br />

cessation <strong>of</strong> Pb exposure were beneficial in reducing skeletal Pb levels.<br />

— Meso—DMSA is the treatment <strong>of</strong> choice <strong>for</strong> acute Pb poisoning in infants<br />

compared to EDTA and Rac-DMSA.<br />

24 h Male Albino rats — S-Adenosyl methionine confers protection against alterations in several<br />

parameters (ALAD, GSH, MDA) indicative <strong>of</strong> lipid peroxidation in blood,<br />

liver and brain in Pb and acute Pb and ethanol exposed animals as well as<br />

the organ concentration <strong>of</strong> Pb.<br />

4 wks Male Albino rats Pb-exposed:<br />

39 µg/dL<br />

Pb + chelators:<br />

4.6–13.1 µg/dL<br />

Sodium molybdate significantly protected the uptake <strong>of</strong> Pb in blood, liver<br />

and kidney. The treatment with molybdate also restored the Pb induced<br />

inhibited activity <strong>of</strong> blood δ-aminolevulinic acid dehydratase and the<br />

elevation <strong>of</strong> blood Zn protoporphyrin , hepatic lipid peroxidation and<br />

serum ceruloplasmin.<br />

Pappas et al. (1995)<br />

Smith et al. (2000)<br />

Kostial et al. (1999)<br />

Flora and Seth<br />

(1999)<br />

Flora et al. (1993)


AX5-168<br />

Table AX5-10.4 (cont’d). <strong>Lead</strong>, Oxidative Stress, and Chelation Therapy<br />

Concentration and<br />

Compound Duration Species Blood <strong>Lead</strong> Effects Reference<br />

20 mg/kg Pb acetate,<br />

i.p.<br />

3 days treatment Male Albino rats — Significant Pb induced inhibition <strong>of</strong> hepatic heme synthesis associated<br />

with decline <strong>of</strong> mixed function oxidases, depletion in anti oxidants such<br />

as vitamin C. Oral supplementation with vitamin C confers protection<br />

against toxic insult by reversing these parameters.<br />

1.5 mg/per bird /d 30 days Broiler chicken — Pb-induced inhibition <strong>of</strong> 5' mono deiodinase (5'- D) activity in chickens<br />

appeared to be mediated through the lipid peroxidative process.<br />

1. Pb acetate<br />

10 mg/mL/kg (a)<br />

2. Ethanol 1 g/<br />

4 mL/kg (b)<br />

3. a + b = (c)<br />

4 a + zinc 10 mg/<br />

4 mL/kg + lysine<br />

25 mg/4 mL/kg<br />

(d)<br />

5. b + 2n + lysine as<br />

in days, oral<br />

6. a + b + Zn +<br />

lysine as in days<br />

1300 ppm Pb acetate<br />

in drinking water<br />

2000 ppm <strong>of</strong> Pb<br />

acetate in drinking<br />

water<br />

500 µM Pb acetate in<br />

cells<br />

2000 ppm <strong>of</strong> Pb<br />

acetate in drinking<br />

water<br />

5 days/wk/8 wk Male Albino rats Control: 1.75 µg/dL<br />

1. 47.23 µg/dL<br />

2. 2.08 µg/dL<br />

3. 45.37 µg/dL<br />

4. 34.19 µg/dL<br />

5. 1.84 µg/dL<br />

6. 46.69 µg/dL<br />

Influence <strong>of</strong> lysine and zinc administration on the Pb-sensitive<br />

biochemical parameters and the accumulation <strong>of</strong> Pb during exposure to<br />

Pb. (1) Pb exposure inhibited blood ALAD activity. Serum enzymes<br />

increased blood and tissue Pb levels. (2) Decreased blood and hepatic<br />

glutathione. Some <strong>of</strong> these effects were enhanced with co-exposure to<br />

ethanol. Simultaneous administration <strong>of</strong> lysine and zinc reduced tissue<br />

accumulation <strong>of</strong> Pb and most <strong>of</strong> the Pb-induced biochemical alterations<br />

irrespective <strong>of</strong> exposure to Pb alone or Pb and ethanol.<br />

5 wks C57BL/6 mice — Pb treatment resulted in depletion <strong>of</strong> GSH, increased GSSG and promoted<br />

Malondialdehyde (MDA) production in both liver and brain samples.<br />

DMSA or N- acetyl cysteine (NAC) treatment resulted in reversion <strong>of</strong><br />

these observations. DMSA treatment resulted in reduced Pb levels in<br />

blood, liver and brain, where as treatment with NAC did not reduce these<br />

levels.<br />

5 wks followed by<br />

treatment with<br />

succimer DMSA, or<br />

thiol agent NAC<br />

Cells—20 h<br />

Animals 5 wks<br />

followed by<br />

treatment with<br />

α-lipoic acid<br />

Fisher 344 male<br />

rats<br />

Male fisher rats<br />

and Chinese<br />

hamster ovary<br />

cells<br />

— Pb induces oxidative stress in RBC and these biochemical alterations are<br />

reversed by both a thiol antioxidant (NAC) as well as a chelating agent<br />

DMSA.<br />

— Pb induces oxidative stress. α-lipoic acid (LA)treatment significantly<br />

increased thiol capacity <strong>of</strong> cells and animals via increasing glutathione<br />

levels and reducing Malondialdehyde levels, increased cell survival.<br />

LA was not effective against reducing blood or tissue Pb levels.<br />

Vij et al. (1998)<br />

Chaurasia et al.<br />

(1998)<br />

Tandon et al. (1997)<br />

Ercal (1996)<br />

Gurer et al. (1998)<br />

Gurer et al. (1999)


AX5-169<br />

Table AX5-10.4 (cont’d). <strong>Lead</strong>, Oxidative Stress, and Chelation Therapy<br />

Concentration and<br />

Compound Duration Species Blood <strong>Lead</strong> Effects Reference<br />

0–500 µM Pb acetate 6 h CHO cells and —<br />

2000 ppm <strong>of</strong> Pb<br />

acetate in drinking<br />

water <strong>for</strong> 5 wks<br />

Taurine<br />

1.1 kg/d<br />

1 mg Pb2+/kg B.wt ,<br />

i.p. Pb acetate<br />

Pb as acetate, 400 mg<br />

Pb2+/mL, drinking<br />

water<br />

0.5 mg/mL<br />

L-methionine<br />

100 µM/kg b.wt. Pb<br />

acetate,<br />

intramuscular, single<br />

100 µg/ Pb acetate,<br />

intra gastric, oral and<br />

intraperitoneal,<br />

treated with or with<br />

out thiamin (25,<br />

50 mg/kg b.wt) and or<br />

Ca EDTA (50 mg/kg<br />

B.wt<br />

5 wks<br />

6th wk<br />

4 wks, treatment<br />

with various<br />

antioxidant in the<br />

5th wk<br />

Fischer 344 rats Controls: 0.43 µg/dL<br />

Pb-exposed:<br />

36.4 µg/dL<br />

Pb + Taurine:<br />

33.8 µg/dL<br />

Antioxidant Taurine reversed the abnormalities associated with lipid<br />

peroxidation parameters such as increased. Malondialdehyde <strong>for</strong>mation<br />

and decreased Glutathione and enhanced CHO cell survival. However,<br />

was not effective in reducing cell and tissue Pb burden in CHO cells and<br />

Pb exposed Fischer rats.<br />

IVRI 2 CQ rats — Pb exposure resulted in increased lipid peroxidation, with tissue specific<br />

changes in liver. Treatment <strong>of</strong> exposed rats with ascorbic acid and αtocopherol<br />

lowered the lipid peroxidation.<br />

10 days Kunming mice<br />

—<br />

4 wks post-Pb<br />

exposure<br />

—<br />

L- methionine has an ameliorative effect on Pb toxicity–Methionine<br />

reduced the decrease in Hb content and depressed body growth caused by<br />

Pb. Treatment with dietary methione along with Pb decreased the MDA<br />

<strong>for</strong>mation as opposed to Pb, moderately reversed the decreased iron<br />

content <strong>of</strong> the organs and decreased organ Pb content.<br />

3 and 24 h Male Albino rats — Pb exposure resulted in significant increases in acid and alkaline<br />

phosphatases, serum GOT and GPT, elevated liver and kidney lipid<br />

peroxidation and decreased antioxidant enzymes at 3 and 24 h after<br />

exposure. Selenium administration prior to Pb exposure produced<br />

pronounced prophylactic effects against Pb exposure by enhancing<br />

endogenous anti oxidant capacity.<br />

3 days CD-1 mice — Two times more whole body Pb was retained by intraperitoneal injection<br />

as compared to intragastric administration. Thiamin treatment increased<br />

the whole body retention <strong>of</strong> both intragastric and intraperitoneal Pb by<br />

about 10%. Calcium EDTA either alone or in combination with thiamin<br />

reduced the whole body retention <strong>of</strong> Pb by about 14% regardless <strong>of</strong> the<br />

route <strong>of</strong> exposure. Regardless <strong>of</strong> the route Ca EDTA in the combined<br />

treatment reduced the relative retention <strong>of</strong> Pb in both in liver and kidney.<br />

These studies indicate the combination treatment with thiamin and Ca<br />

EDTA alters the distribution and retention <strong>of</strong> Pb in a manner which might<br />

have therapeutic application.<br />

Gurer et al. (2001)<br />

Patra et al. (2001)<br />

Xie et al. (2003)<br />

Othman and El<br />

Missiry (1998)<br />

Kim et al. (1992)


AX5-170<br />

Table AX5-10.4 (cont’d). <strong>Lead</strong>, Oxidative Stress, and Chelation Therapy<br />

Concentration and<br />

Compound Duration Species Blood <strong>Lead</strong> Effects Reference<br />

2000 ppm Pb acetate,<br />

oral<br />

I chelators<br />

LA, DMSA,<br />

MiADMSA<br />

LA + DMSA + LA+<br />

MiADMSA<br />

0.1% Pb as acetate in<br />

drinking water<br />

DMSA—50 mg/kg,<br />

i.p./d<br />

MiADMSA—50<br />

mg/kg, i.p./d<br />

Vitamin E 5 mg/kg<br />

and vitamin C<br />

25 mg/kg/d, i.v. and<br />

oral<br />

500 mg/kg Pb acetate<br />

daily, oral treatment<br />

with chelators<br />

Pb as acetate 0.2% in<br />

drinking water<br />

LA 25 mg/kg b.wt and<br />

DMSA 20 mg/kg b.wt<br />

Abbreviations<br />

4 wks, 5 days <strong>of</strong><br />

treatment with<br />

antioxidant or<br />

chelators<br />

Male Wistar<br />

albino rats<br />

Normal: 1.42 µg/dL<br />

Pb: 40.93 µg/dL<br />

Pb + chelators: 38.5–<br />

4.27 µg/dL<br />

3 mo Male Wistar rats<br />

—<br />

5 days post-Pb<br />

exposure<br />

Multiple durations<br />

(2, 4, and 6 wks)<br />

5 wks followed by<br />

a 6th wk<br />

administration <strong>of</strong><br />

LA and or DMSA<br />

b. wt.—body weight<br />

a CYP—Cytochrome P-450<br />

SOD—Super oxide dismutase<br />

GSH—Glutathione<br />

GSH/GSSG Ratio—Reduced Glutathione/Oxidized Glutathione<br />

MDA—Malondialdehyde<br />

Al—Aluminum<br />

As—Arsenic<br />

MiDMSA—Mi monoisoamyl DMSA<br />

—<br />

Male Albino rats Control: 0.32 µg/dL<br />

Pb-exposed:<br />

0.48–0.56 µg/dL<br />

Pb + chelators:<br />

0.32–0.36 µg/dL<br />

Treatment with all the chelators reduced hepatic GSH and reduced GSSG<br />

levels. Significant beneficial role <strong>of</strong> Alpha-lipoic acid (LA), in recovering<br />

the altered biochemical parameters, however showed no chelating<br />

properties in lessening body Pb burden either from blood, liver, or kidney.<br />

Most beneficial effects against Pb poisoning was observed with combined<br />

treatment <strong>of</strong> lipoic acid and either DMSA (meso 2,3-dimercaptosuccinic<br />

acid) or MiADMSA (Mono isoamyl DMSA).<br />

Single or combined administration <strong>of</strong> vitamin C, α-tocopherol and the<br />

chelators DMSA and Mi ADMSA against the Parameters <strong>of</strong> Pb induced<br />

oxidative stress– thiol chelators and the vitamins could bring the blood<br />

ALAD to normal levels, most significantly by combined administration <strong>of</strong><br />

Mi ADMSA with vitamin C. Vitamin C and E were effective against<br />

reducing oxidized glutathione ( GSSG), and thibarbituric acid reactive<br />

substance(TBARS) and increasing catalase activity. MiADMSA and<br />

DMSA with vitamin C were effective in increasing hepatic GSH levels.<br />

In summary combined treatment regimens with thiol chelators and<br />

vitamins seem very effective in reducing the Pb induced oxidative stress.<br />

Impact <strong>of</strong> combined administration <strong>of</strong> vitamin C and Sylimarin on Pb<br />

toxicity. Combined treatment <strong>of</strong> Pb-exposed animals with vitamin C and<br />

Silymarin showed marked improvement <strong>of</strong> the adverse biochemical,<br />

molecular and histopathological signs associated with Pb toxicity.<br />

Male Albino rats — Pb treatment <strong>for</strong> 5 wks resulted hepatic enzymes alanine transaminase,<br />

aspartate transaminase, and alkaline phosphatase, increased lipid<br />

peroxidation, and decreased hepatic anti oxidant enzymes. LA or DMSA<br />

alone, partially abrogated these effects, however, in combination<br />

completely reversed the lipid oxidative damage.<br />

Cr—Cromium<br />

V—Vanadium<br />

Pb—<strong>Lead</strong><br />

NAC—N acetyl cysteine<br />

FeSO 4 —Ferrous sulphate<br />

AlCl3—Aluminum chloride<br />

VCl3—Vanadium chloride<br />

CdCl2,—Cadmium chloride<br />

CuSO 4 —Copper sulphate<br />

CrCl3—Cromium chloride<br />

MnCl2—Manganese chloride<br />

NiSO 4 —Nickel sulphate<br />

CoCl2—Cobalt chloride<br />

LAN—" Linolenic acid<br />

DPPD—DPPD,N-N Diphenyl –p-phynylene-diamine<br />

LA—Lipoic acid<br />

DMSA—Monoisoamyl DMSA<br />

Pande and Flora<br />

(2002)<br />

Flora et al. (2003)<br />

Shalan et al. (2005)<br />

Sivaprasad et al.<br />

(2004)


AX5-171<br />

Table AX5-10.5. <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular Mechanisms<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

— — Rat — Apoptosis plays a major role in the regressive phase <strong>of</strong> Pb nitrate induced<br />

hepatic hyperplasia as detected by the apoptotic bodies by in situ end<br />

labeling and HandE sections <strong>of</strong> the hepatic tissue. HandE scores mostly<br />

cells in apoptosis phase <strong>II</strong>, ISEL (in situ end labeling) scores <strong>for</strong> cells in<br />

phase I. Combination <strong>of</strong> these two methods is suggested <strong>for</strong> the better<br />

understanding <strong>of</strong> the extent and nature <strong>of</strong> apoptotic process in liver cells<br />

treated with chemicals.<br />

A. Pb nitrate,<br />

100 µM/kg b.wt,<br />

intra-gastric<br />

B. Diethyl<br />

nitrosoamine<br />

200 mg/kg b.wt, i.p.<br />

0–100 µM Pb<br />

sulphate, Pb<br />

monoxide, Pb<br />

chloride and Pb<br />

acetate up to 1 mM,<br />

culture media.<br />

Choline 1g/kg/d in<br />

drinking water<br />

Pb nitrate, 75 µM/kg<br />

b.wt, single i.v.<br />

75 µmol/kg b. wt. Pb<br />

nitrate in adult and 20<br />

µg/mL in the young,<br />

i.v.; single dose<br />

3 and 15 days Male Wistar<br />

Albino rats<br />

Multiple time points<br />

ranging from 24 h<br />

up to 7 days<br />

0, 20, and 24 h Male and female<br />

rats , partial<br />

hepatectomy<br />

6 h–4 wks Adult male Albino<br />

rats<br />

Analyses at 72 h Male Wistar<br />

Albino rats<br />

— Mitogenic stimuli (3 days Pb nitrate treatment) and complete regression<br />

(15 days after the treatment), affected the apoptosis differentially.<br />

Influence <strong>of</strong> apoptosis Vs necrosis on the growth <strong>of</strong> hepatocytes initiated<br />

by diethyl nitrosamine followed by Pb nitrate treatment indicated that the<br />

regenerative response elicited by a necrogenic dose <strong>of</strong> CCL4 promoted<br />

GSTP (Placental glutathione), a pre-neoplastic marker positive cells as<br />

against the Pb nitrate that induced the apoptosis.<br />

REL liver cells — Pb compounds showed a dose and time related effect on REL liver cell<br />

proliferation with varying potencies specific to the different Pb salts.<br />

Pb acetate was the most effective and Pb monoxide, the least effective.<br />

On 1 hr treatment none <strong>of</strong> the compounds tested affected the intracellular<br />

communication.<br />

— PKC isozymes during liver cell regeneration— PKC δ showed a<br />

pronounced increase 20h after partial hepatectomy. α, β, and Zeta at 24 h<br />

corresponding with S-phase. Sexual dimorphism matching with sexual<br />

differences in DNA synthesis was evident. Administration <strong>of</strong> choline was<br />

able to modulate the protein kinase C isozyme pattern in females in<br />

relation to DNA synthesis and c-myc expression. Taken together the data<br />

positively implicates α, β, and Zeta in growth after partial hepatectomy<br />

and δ in negative regulation.<br />

— Pb induced significant increase in liver weight. Increased 3H Thymidine<br />

incorporation. Pb induces extensive hypomethylation in treated rat livers.<br />

Site-specific effect on methylation was confirmed at Hpa <strong>II</strong>, Msp I,<br />

Hae <strong>II</strong>I.<br />

— Effect <strong>of</strong> Pb nitrate on the 5- methyl deoxy cytidine (5-mdcyd) content and<br />

the Hpa<strong>II</strong>, MSPI, Hae <strong>II</strong>I restriction patterns <strong>of</strong> hepatic DNA from young,<br />

middle aged and senescent rats. The results indicated that the methylation<br />

pattern <strong>of</strong> genomic DNA changed significantly with age and the<br />

methylation patterns were differentially affected in all the three<br />

populations.<br />

Nakajima et al.<br />

(1995)<br />

Columbano et al.<br />

(1996)<br />

Apostoli et al.<br />

(2000)<br />

Tessitore et al.<br />

(1995)<br />

Kanduc et al. (1991)<br />

Kanduc and Prisco<br />

(1992)


AX5-172<br />

Table AX5-10.5 (cont’d). <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular Mechanisms<br />

Concentration Duration Species Blood Level Effects a Reference<br />

10 µmol/100 g body<br />

weight Pb nitrate, i.v.<br />

100 µmol/kg, b. wt.<br />

Pb nitrate, i.v.<br />

Multiple analyses<br />

up to 40 h<br />

Analyses at multiple<br />

time points,<br />

0.25–24 h<br />

Male Wistar rats,<br />

hepatocytes<br />

from partial<br />

hepatectomy and<br />

Pb nitrate<br />

treatment.<br />

Male Wistar<br />

Albino rats<br />

100 µmol/kg b. wt. 8 h Male Sprague<br />

Dawley rats<br />

100 µmol/kg b. wt.,<br />

i.v.<br />

100 µ mol/kg b. wt.,<br />

i.v. Pb nitrate<br />

Multiple analyses<br />

time points,<br />

1–120 h<br />

Analyses at multiple<br />

time points, 8 h to<br />

15 days<br />

— The kinetics <strong>of</strong> DNA synthesis and expression <strong>of</strong> Proto oncogenes in<br />

partially hepatectamized liver cells and Pb nitrate treated hepatic cells<br />

indicated peak DNA synthesis after 24 h in the <strong>for</strong>mal and after 36 h in the<br />

later case. Both proliferative stimuli induced c-fos, c-myc and c-Ha Ras<br />

expression. Induced c-myc expression persisted <strong>for</strong> up to 40h during the<br />

Pb nitrate- induced liver cell proliferation. Pb induces hepatic hyperplasia<br />

through changes in proto-oncogene expression.<br />

— Proliferative stimuli by means <strong>of</strong> Pb nitrate exposure resulted in increased<br />

expression <strong>of</strong> c-jun m-RNA where as compensatory regeneration in<br />

partially hepatectamized cells occurred through increased expression <strong>of</strong> cfos<br />

and c-jun. Different mitogenic stimuli induced differential expression<br />

<strong>of</strong> these protooncogenes, in addition had a different pr<strong>of</strong>ile than cells from<br />

partial hepatectomy despite the cell cycle timings being the same in some<br />

cases.<br />

— In rat liver, in addition to a few hepatocytes four types <strong>of</strong> non parenchymal<br />

cells namely, fibroblasts, macrophages, bile ducts and periductular cells<br />

proliferate in response to Pb nitrate treatment. This growth is not related<br />

to adaptive response secondary to parenchymal enlargement. However,<br />

such growth in parenchymal cells seems dormant and does not play a<br />

functional role in adult liver epithelial growth.<br />

Male Wistar rats — Both mRNA levels and enzyme activity <strong>of</strong> DNA polymerase β markedly<br />

increased be<strong>for</strong>e and/or during DNA synthesis in proliferating hepatocytes<br />

in Pb nitrate treated and partially hepatectomized rats. 5 fold increase in<br />

the enzyme activity was observed 8 h after Pb nitrate administration. In<br />

the regenerative liver cells a 3 fold increase was observed 24–48h after<br />

partial hepatectomy.<br />

Male Wistar rats — Pb nitrate induced Poly (ADP-ribose) polymerase mRNA 24 hr after<br />

exposure. A 2 fold increase in the mRNA levels <strong>of</strong> the enzyme occurred<br />

2 days after the exposure. Such changes were also observed in hepatic<br />

cells from livers <strong>of</strong> partial hepatectomy. These changes preceded the<br />

increase in DNA synthesis and remained high during the time <strong>of</strong> extensive<br />

DNA synthesis.<br />

Coni et al. (1989)<br />

Coni et al. (1993)<br />

Rijhsinghani et al.<br />

(1992)<br />

Menegazzi et al.<br />

(1992)<br />

Menegazzi et al.<br />

(1990)


AX5-173<br />

Table AX5-10.5 (cont’d). <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular Mechanisms<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

30 mg/kg b. wt.<br />

Pb nitrate<br />

30 mg/kg b. wt.<br />

Pb nitrate<br />

100 µmol/kg b. wt.<br />

Pb nitrate, i.v., single<br />

dose.<br />

A. Mitosis—<br />

Pb nitrate<br />

100 µM/kg, i.v.<br />

Ethylene<br />

dibromide<br />

100 mg/kg , intra<br />

gastric<br />

Cyproterone<br />

acetate, 60 mg/kg<br />

intra gastric.<br />

B. Hepatocyte<br />

nodules diethyl<br />

nitrosamine<br />

200 mg/kg<br />

Pb nitrate, single i.v.<br />

100 µm/kg b.wt<br />

LPS—12.5 µg/rat,<br />

post Pb nitrate<br />

treatment.<br />

Multiple time points<br />

up to 8 days<br />

Multiple time point<br />

up to 60 h<br />

Multiple time point<br />

analyses ranging<br />

from 12–168 h<br />

Adult male and<br />

female rats<br />

Adult male and<br />

female rats<br />

30'–3 h Adult male Wistar<br />

rats<br />

Multiple analyses at<br />

3, 6, 12, 24, and<br />

36 h<br />

Male Wistar rats Serum Pb<br />

concentrations<br />

peaking to 50–<br />

60 µg/dL between<br />

12–24 h and<br />

remaining up to<br />

40 µg/dL up to 108 h<br />

— Pb nitrate induced liver hyperplasia exhibited sexual dimorphism where<br />

mitogenic action was less effective and was delayed in females as<br />

compared with males. Pre administration with choline partially filled<br />

these sexual differences.<br />

— Pb nitrate induced liver hyperplasia exhibited sexual dimorphism.<br />

Pre-administration with choline partially filled these sexual differences.<br />

Significant down regulation <strong>of</strong> PKC β and PKC α activities occurred<br />

during Pb induced proliferation.<br />

Effect <strong>of</strong> Pb nitrate on protein kinase C (PKC) activity. A single dose <strong>of</strong><br />

Pb nitrate resulted in enhanced activity <strong>of</strong> PKC in the purified particulate<br />

fraction <strong>of</strong> the rat liver, reached its peak activity by 24 h which lasted <strong>for</strong><br />

48 h. This was accompanied by increased frequency <strong>of</strong> mitotic cells.<br />

These results indicate, Pb nitrate induced PKC activity may play a role in<br />

liver cell proliferation.<br />

— Liver cell proliferation by enhanced DNA synthesis was observed with the<br />

mitogens Cyproterone acetate, ethylene dibromide, and Pb nitrate as early<br />

as 30 mints after treatment and persisted even after 5 days <strong>of</strong> treatment by<br />

Pb nitrate administration.<br />

hepatocytes isolated from pre neoplastic liver nodules have also exhibited<br />

enhanced cell proliferation.<br />

Male Wistar rats — Stimulation <strong>of</strong> hepatocyte cell proliferation by Pb nitrate was not<br />

accompanied by changes in liver levels <strong>of</strong> Hepatocyte growth factor<br />

(HGF), Trans<strong>for</strong>ming growth factor-α (TGF-α), or TGF-β1 m-RNA. Pb<br />

nitrate treatment resulted in the enhancement <strong>of</strong> Tumor necrosis factor α at<br />

a time preceding the onset <strong>of</strong> hepatocyte DNA synthesis, indicating its role<br />

in Pb induced hepatic cell proliferation. The survival <strong>of</strong> Pb nitrate treated<br />

rats decreased significantly with an after treatment <strong>of</strong> LPS<br />

(lipopolysaccharide).<br />

Tessitore et al.<br />

(1994)<br />

Tessitore et al.<br />

(1994)<br />

Liu et al. (1997)<br />

Coni et al. (1992)<br />

Shinozuka et al.<br />

(1994)


AX5-174<br />

Table AX5-10.5 (cont’d). <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular Mechanisms<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

15 mg/kg b. wt.<br />

Pb acetate<br />

Pb nitrate 100 µM/kg<br />

b. wt. i.v. single dose<br />

100 µmol/kg b. wt<br />

Pb nitrate, single, i.v.<br />

100 µmol/kg b. wt.<br />

single i.v.<br />

100 µmol/kg b. wt.<br />

i.v. single dose<br />

100 µmol/kg b. wt.<br />

i.v., single dose<br />

Pb+ LPS group<br />

analyzed after 14 h<br />

and the rest after<br />

24 h after Pb<br />

administration<br />

Multiple time points<br />

<strong>of</strong> analyses<br />

extending up to 48 h<br />

after treatment<br />

Multiple time points<br />

<strong>of</strong> analyses up to<br />

48 h<br />

Multiple time points<br />

<strong>of</strong> analyses up to<br />

80 h<br />

Multiple time points<br />

<strong>of</strong> analyses up to<br />

24 h<br />

Multiple time point<br />

analyses up to 96 h<br />

Male Sprague<br />

Dawley rat<br />

— Pb augments the lethality <strong>of</strong> endotoxin lipopolysaccharide (LPS) in rats<br />

and enhances liver injury, which is further enhanced by TNF. Pb + LPS<br />

treatment increased both serum TNF concentrations and TNF area as<br />

compared to LPS alone. simultaneous administration <strong>of</strong> Pb with either<br />

LPS or TNF, serum aspartate transaminase, alanine transaminase, alkaline<br />

phosphatase, glutamyl trans peptidase and plasma triglyceride levels were<br />

markedly increased.<br />

Male Wistar rats — Pb nitrate and ethylene bromide induce liver cell proliferation via<br />

induction <strong>of</strong> TNFα. Dexa methasone, a known TNF inhibitor, decreases<br />

TNF expression and liver cell proliferation by these mitogens. These<br />

studies support the fact that TNF might mediate hepatic cell proliferation<br />

by Pb nitrate and ethylene bromide.<br />

Male Sprague<br />

Dawley rats<br />

— Pb nitrate (LN) treatment resulted in increased Brdu incorporation <strong>of</strong><br />

hepatocytes and non parenchymal cells at 12 h after treatment and reached<br />

the peak index at 36 h. Rats given a single i.v. <strong>of</strong> recombinant TNFα<br />

enhanced proliferation in non parenchymal cells after 24 h, the labeling <strong>of</strong><br />

hepatocytes at 36 h. NAF, Nafenopin another mitogen which does not<br />

induce liver TNFα, increased the number <strong>of</strong> labeled hepatocytes without<br />

increasing the labeling <strong>of</strong> non parenchymal cells indicating that only Pb<br />

nitrate induced proliferation is mediated by TNFα and these mitogens<br />

initiate proliferation in different cells based on their capacity to stimulate<br />

TNFα production.<br />

— Pb nitrate induces liver cell proliferation in rats without accompanying<br />

liver cell necrosis. This proliferation involves enhanced TNF mRNA and<br />

levels but not hepatocyte growth factor. The role <strong>of</strong> TNF in Pb nitrate<br />

induced liver cell proliferation is supported by the inhibition <strong>of</strong> TNF and<br />

reduced hepatocyte proliferation by several TNF inhibitors.<br />

Male Wistar rats — Pb nitrate induced liver cell proliferation involves TNF α production,<br />

enhanced NF-κB activation increased hepatic levels <strong>of</strong> iNos mRNA as<br />

opposed to other mitogens such as Cyproterone acetate or Nafenopine.<br />

Male Sprague<br />

Dawley rats<br />

— The role <strong>of</strong> neurotrophins, the nerve growth factor (NGF), the brain<br />

derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in Pb<br />

nitrate treated liver cells was studied. LN, treatment resulted in increased<br />

in the levels <strong>of</strong> NGF, BDNF and NT-3. The increase in neurotrophin<br />

receptors and the gene expression were correlate with liver weights. This<br />

study demonstrates that Pb nitrate induced hyperplasia may be mediated<br />

by neurotrophins.<br />

Honchel et al.<br />

(1991)<br />

Ledda-Columbano<br />

et al. (1994)<br />

Shinozuka et al.<br />

(1996)<br />

Kubo et al. (1996)<br />

Menegazzi et al.<br />

(1997)<br />

Nemoto et al.<br />

(2000 )


AX5-175<br />

Table AX5-10.5 (cont’d). <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular Mechanisms<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Multiple doses<br />

0–50 µM, culture<br />

medium<br />

50 µM Pb acetate,<br />

culture medium<br />

10 µM/110 g b. wt.,<br />

single i.v.<br />

10 µmol/100 g b. wt.<br />

single i.v.<br />

10 mmol/100 g,<br />

Pb nitrate, i.v.<br />

Multiple time points<br />

up to 24 h<br />

Hepatocytes from<br />

Adult male Swissmice,<br />

primary<br />

24 h Rat hepatocyte<br />

and Kupffer cell<br />

and granulocyte<br />

co-cultures<br />

Multiple time point<br />

analyses up to<br />

5 days<br />

Multiple time points<br />

up to 9 days<br />

Adult male Wistar<br />

rats<br />

— Interaction between Pb and cytokines in hepatotoxicity– Pb potentiated<br />

cytokine-induced oxidative stress by decreasing GSH and increased efflux<br />

<strong>of</strong> Oxidized glutathione (GSSG). Combined treatment resulted in a<br />

decline in intra cellular ATP concentration.<br />

— Pb stimulates intercellular signaling between Kupffer cells and<br />

hepatocytes which increased synergistically at low lipopolysaccharide<br />

levels. These signals promote proteolytic hepatocyte killing in<br />

combination with a direct cellular interaction between the granulocytes<br />

and hepatocytes.<br />

— Pb nitrate induced hepatocyte apoptosis was prevented by pre-treatment<br />

with gadolinium chloride, a Kupffer cell toxicant—Role <strong>for</strong> Kuffer cell in<br />

hepatocyte apoptosis.<br />

Male Wistar rats — Pb nitrate-induced liver hyperplasia in rats results in a significant increase<br />

in the expression <strong>of</strong> aceyl glycoprotein receptor (ASGP-R) during the<br />

involutive phase <strong>of</strong> Pb nitrate induced hyperplasia in rat-liver, which<br />

coincided with the massive death by apoptosis <strong>of</strong> the same cells.<br />

A significant rise in the galactose-specific receptors was also observed<br />

3 days after the treatment. These studies demonstrate that carbohydrate<br />

receptors regulate Pb nitrate induced liver cell apoptosis.<br />

Multiple time points Male Wistar rats — Demonstration <strong>of</strong> the expression <strong>of</strong> carbohydrate receptors on Kupffer<br />

cells. Pb nitrate induced apoptosis in Kupffer cells and internalization <strong>of</strong><br />

apoptotic cells (Phagocytes) is mediated by both Mannose and Galactose<br />

receptors.<br />

Sieg and Billing<br />

(1997)<br />

Milosevic and<br />

Maier (2000)<br />

Pagliara et al.<br />

(2003a)<br />

Dini et al. (1993)<br />

Ruzittu et al. (1999)


AX5-176<br />

Table AX5-10.5 (cont’d). <strong>Lead</strong>-induced Liver Hyperplasia: Mediators and Molecular Mechanisms<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Pb (No3)2, , i.v.<br />

100 µM/110 g .b. wt<br />

GdCl3<br />

0.75 mg/100 g. b. wt,<br />

i.v.<br />

In vitro, 10 mM Pb<br />

nitrate<br />

Multiple<br />

concentrations<br />

varying from<br />

300 nM–10 µM,<br />

up to 100 µM in<br />

certain in vitro expts<br />

0–10 µM Pb acetate<br />

in the culture medium<br />

a CYP—Cytochrome P-450<br />

b. wt.—body weight<br />

1, 3, and 5 days In vivo Adult<br />

male Wistar rats<br />

2, 4, or 24 h be<strong>for</strong>e Pb<br />

nitrate injection.<br />

Analyses at multiple<br />

time points up to 24 h<br />

in Hep G2 cells and at<br />

24 and 48 h in<br />

Kupffer cells<br />

1, 2, 4 and 6 days Hepatoma cell<br />

line, H4-<strong>II</strong>-C3<br />

24 and 48 h H4-<strong>II</strong>E—C3<br />

hepatoma cell<br />

culture model<br />

—<br />

—<br />

Hep G2 cells —<br />

Hepatic apoptosis induced by Pb nitrate in vivo is abolished by gadolium<br />

chloride, a Kupffer cell toxicant that suppresses Kupffer cell activity and<br />

reduces to half the apoptotic rate. Pb nitrate treatment also deprives the<br />

hepatic cells from reduced glutathione and this process is reversed by<br />

Gadolium chloride. Pb nitrate induces apoptosis in Kupffer cells, and<br />

HepG2 cells in vitro.<br />

— Acute effect <strong>of</strong> Pb on glucocorticoid regulation <strong>of</strong> Tyrosine<br />

aminotransferase (TAT) in hepatoma cells. Pb treatment does not<br />

significantly alter initial glucocorticoid receptor number or ligand binding.<br />

Pb may perturb PKC mediated phosphorylations in the glucocorticoid-<br />

TAT signal transduction system. Pb also may be increasing the turnover<br />

<strong>of</strong> TAT by actions at transcription, translation and /or post translation.<br />

— In HTC cells glucocarticoid signal transduction pathways involve calcium-<br />

mediated events and PKC iso<strong>for</strong>ms, Pb exposure interferes with calcium<br />

mediated events and aberrant modulation <strong>of</strong> PKC activities and may<br />

contribute to the over all toxicity <strong>of</strong> Pb.<br />

Pagliara (2003b)<br />

Heiman and Toner<br />

(1995)<br />

Tonner and Heiman,<br />

(1997)


AX5-177<br />

Table AX5-10.6. Effect <strong>of</strong> <strong>Lead</strong> Exposure on Liver Heme Synthesis<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

75 mg Pb/kg b. wt.,<br />

i.p.<br />

Multiple time point<br />

analyses 0–30 h<br />

10 −5 ppm Pb nitrate Multiple analyses up<br />

to 24 h<br />

A. Triethyl Pb-3.5<br />

and 8.0 mg/kg<br />

b.wt.<br />

Pb nitrate<br />

3.5, 25, and<br />

100 mg/kg<br />

Single<br />

Subcutaneous<br />

B. In vitro,<br />

10 −3 –10 −9 M<br />

triethyl Pb or Pb<br />

nitrate<br />

5 µM Pb acetate or<br />

Pb diethyldithiocarbomate<br />

Pb uptake<br />

studies 0.33–10 µM<br />

Per OS eqimolar<br />

doses (17 µM Me/kg)<br />

<strong>of</strong> SnCl 2 or Pb<br />

(CH3COO)2 every day<br />

Multiple analyses up<br />

to 28 days<br />

30 min<br />

Multiple analyses<br />

from<br />

0–20 h<br />

C57 BL/6 mice — Pb poisoning decreases P-450 as a consequence <strong>of</strong> two different<br />

mechanisms, a mechanism unrelated to heme where P-450 transcription is<br />

inhibited (reduces the synthesis and activity), and a second mechanism<br />

where by inhibition <strong>of</strong> heme synthesis occurs decreasing the heme<br />

saturation <strong>of</strong> P450 and/or apo-P450 content.<br />

RLC-GA1 Rat<br />

liver cell line<br />

Adult male<br />

Fischer rats<br />

Rat primary<br />

hepatocyte<br />

cultures<br />

— Pb increases heme synthesis in RLC-GA1 in rat liver cell line, when<br />

measured by the amount <strong>of</strong> 59 Fe incorporated into heme fraction.<br />

Increased incorporation <strong>of</strong> 59 Fe into the heme fraction <strong>of</strong> the Pb treated<br />

cells was the result <strong>of</strong> increased uptake <strong>of</strong> iron 59 Fe into the heme fraction<br />

<strong>of</strong> Pb treated cells.<br />

Cellular degradation <strong>of</strong> Pb was not significantly affected by Pb.<br />

Control: 5.2 µg/dL<br />

Triethyl Pb 8.0 mg/kg<br />

b.wt.:<br />

19.6 µg/dL<br />

Pb nitrate<br />

25 mg/kg b.wt.:<br />

19.6 µg/dL<br />

Pb nitrate<br />

100 mg/kg b.wt.:<br />

27.2 µg/dL<br />

5 days Female rabbits Control:<br />

3.48 µg/100 cm 3<br />

Pb: 17.50 µg/100 cm 3<br />

—<br />

Triethyl Pb chloride has a similar potency to inorganic Pb nitrate in<br />

inhibiting ALAD both in vitro and in vivo. Liver and blood ALAD have<br />

similar sensitivities to Pb compounds. Inhibition is reduced in the<br />

presence <strong>of</strong> Zn.<br />

— Effect <strong>of</strong> Pb and diethyl dithiocarbomates on rat primary hepatocytes as<br />

studied with Pb acetate and or Pb-diethyldithiocarbomate complex (Pb<br />

DTC2l) labeled with 203 Pb indicated that (Pb DTC2l) complex caused a<br />

more rapid and stronger inhibition <strong>of</strong> ALAD activity than Pb acetate.<br />

Uptake <strong>of</strong> Pb was rapid and higher with the complex than Pb acetate.<br />

The complex also inhibited the ALAD activity in vitro when incubated<br />

with purified ALAD enzyme.<br />

Pb decreased liver and bone marrow ALAD, but had no change in the<br />

Aminolevulinic acid synthetase (ALA-S) and increased erythrocyte free<br />

protoporphyrin.<br />

Jover et al. (1996)<br />

Lake and<br />

Gerschenson (1978)<br />

Bondy (1986)<br />

Oskarsson and<br />

Hellström-Lindahl<br />

et al. (1989)<br />

Zareba and<br />

Chmielnicka (1992)


AX5-178<br />

Table AX5-10.6 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> Exposure on Liver Heme Synthesis<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Pb 500 ppm in<br />

drinking water<br />

0.5 or 2.4 µM Pb<br />

acetate in culture<br />

medium<br />

500 ppm Pb in<br />

drinking water<br />

A. Cu deficient diet:<br />

1 mg/kg Cu in<br />

the diet<br />

B. Moderately<br />

deficient:<br />

2 mg/kg<br />

C. High Zn diet:<br />

60 mg/kg b. wt.<br />

1200 mg/kg b. wt. Pb<br />

acetate in diet, Sub<br />

acute toxic studies<br />

400 mg/Pb<br />

0–100 µM Pb acetate<br />

in the culture medium<br />

14 days Male ddY mice — Urinary excretion <strong>of</strong> β-Aminoisobutyric acid (ABA) and δ-aminolevulinic<br />

acid (ALA) increased significantly in mice exposed to Pb in drinking<br />

water <strong>for</strong> 14 days. The degree <strong>of</strong> increasing excretion <strong>for</strong> ALA was higher<br />

than urinary ABA. Liver and kidney ALA dehydratase was inhibited,<br />

while ALA synthatase was not affected.<br />

Analyses at multiple<br />

time points,<br />

0–28 days<br />

Rat exposure 62 days<br />

Human occupational<br />

exposure<br />

0.3–38 yrs.<br />

Hepatocyte<br />

cultures on 3T3<br />

cells<br />

A. Male Wistar<br />

rats<br />

B. Pb smelt<br />

workers, males<br />

4 wks Weanling<br />

Sprague Dawley<br />

rats<br />

— Hepatocyte cultures on 3T3 cells produce and excrete porphyrins <strong>for</strong><br />

28 days. Pb exposure <strong>for</strong> 4 wks alters cell morphology and produces<br />

cytotoxic effects that could be monitored by altered porphyrin excretion.<br />

— Pb exposure significantly increases the urinary ALA (Aminolevulinic<br />

acid) and Coproporphyrins (CP-<strong>II</strong>I>CP-I in rats and exposed workers.<br />

Urinary 5-hydroxy indole acetic acid was not influenced by Pb exposure.<br />

— High Zn in the diet reduces plasma copper, but not plasma ceruloplasmin<br />

activity or the recovery <strong>of</strong> plasma copper or ceruloplasmin activity after<br />

oral copper sulphate <strong>of</strong> Cu-deficient rats. High dietary Zn also modifies<br />

the response <strong>of</strong> plasma SOD activity to dietary copper , but does not<br />

influence RBC SOD activity.<br />

4 wks Broiler chickens — Liver porphyrin levels increased during Pb toxicosis. Concurrent<br />

administration <strong>of</strong> selenium or monensin in the feed further enhances this<br />

process.<br />

19 h Primary Rat and<br />

chick embryo<br />

hepatocyte<br />

cultures<br />

— Formation <strong>of</strong> Zn protoporphyrins in cultured hepatocytes. Pb did not<br />

specifically increase Zinc protoporphyrin accumulation or alter iron<br />

availability in cultured hepatocytes.<br />

Tomokuni et al.<br />

(1991)<br />

Quintanilla-Vega<br />

et al. (1995)<br />

Ichiba and<br />

Tomokuni (1987)<br />

Panemangalore and<br />

Bebe (1996)<br />

Khan and Szarek<br />

(1994)<br />

Jacobs et al. (1998)


AX5-179<br />

Table AX5-10.6 (cont’d). Effect <strong>of</strong> <strong>Lead</strong> Exposure on Liver Heme Synthesis<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

Pb acetate, 160 mg/L,<br />

semi liquid diet, oral<br />

Pb acetate,<br />

0.0625 µM–32 µM,<br />

in vitro<br />

1, 5, or 10 mg/kg<br />

b. wt. Pb acetate or<br />

nitrate, i.p.<br />

10 −4 M Pb acetate <strong>for</strong><br />

Hep G2 cells<br />

10 mg Pb/kg b. wt. as<br />

Pb acetate , i.p., single<br />

injection<br />

10 and 100 µM Pb<br />

acetate<br />

a CYP—Cytochrome P-450<br />

b. wt = body weight<br />

8 wks Male Wistar rats — Rats exposed to Pb had a higher blood and liver Pb, increased erythrocytic<br />

protoporphyrin. Pb exposure also resulted in hypoactivity <strong>of</strong><br />

aminolevulinate dehydrase.<br />

Rats exposed to ethanol and Pb had altered abnormalities in heme similar<br />

to animals exposed to Pb alone.<br />

Hepatic levels <strong>of</strong> Zn decreased significantly only in animals exposed to<br />

both.<br />

Hepatic GSH, urinary ALA and porphyrin levels were maintained<br />

similarly in all the groups.<br />

Transferrin bound iron uptake by Pb was also inhibited by Pb at higher<br />

concentrations such as 4 µM.<br />

10 min pre incubation<br />

and 20 minute<br />

incubation<br />

3 days<br />

Analyses at multiple<br />

time points up to 72 h<br />

Rabbit<br />

reticulocytes<br />

A. Transgenic<br />

mice carrying<br />

chimeric<br />

human TF<br />

gene<br />

— The effect <strong>of</strong> Pb on ferrous iron transport is similar between Pb chloride,<br />

acetate, and nitrate and reversible.<br />

Uptake <strong>of</strong> ferrous iron into all (heme, cytosolic and stromal fractions) was<br />

inhibited by low concentrations <strong>of</strong> Pb.<br />

50% inhibition in the uptake by cytosol occurred at 1 µM Pb.<br />

— These studies present evidence <strong>for</strong> the modulation <strong>of</strong> the synthesis <strong>of</strong><br />

human transferrin by Pb. In transgenic mouse with chimeric human<br />

chloromphenical acetyl transferase Pb regulates human Transferrin (TF)<br />

transgenes at the m RNA level. Liver catalase (CAT) enzyme activity,<br />

CAT protein, and TF-CAT m-RNA levels were all suppressed. Pb did not<br />

alter other liver proteins, mouse TF and Albumin.<br />

B. Hep G2 cells — Pb suppressed synthesis <strong>of</strong> Transferrin protein in cultured human<br />

hepatoma Hep G2 cells.<br />

Transgenic mice<br />

and Hep G 2<br />

cells<br />

— Pb suppresses human transferrin synthesis by a mechanism different from<br />

acute phase response. Common proteins such as C3 and albumin<br />

associated with acute phase response were not altered by Pb. Pb acetate<br />

suppresses 35 S-transferrin protein synthesis and m-RNA levels in Hep G2<br />

cells and transgenic mice, while LPS altered only protein levels.<br />

Santos et al. (1999)<br />

Qian and Morgan<br />

(1990)<br />

Adrian et al. (1993)<br />

Barnum-Huckins<br />

et al. (1997)


AX5-180<br />

Table AX5-10.7. <strong>Lead</strong> and In Vitro Cytotoxicity in Intestinal Cells<br />

Compound and<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Reference<br />

HgCl2, CdCl2, Ti2<br />

SO4, Pb(NO3)2–<br />

concentration not<br />

given clearly,<br />

Butathionine, up to<br />

1 mM<br />

Glutathione 1 mM<br />

N-Acetyl cysteine,<br />

1 mM<br />

a CYP—Cytochrome P-450<br />

Cell proliferation<br />

assays 48 h<br />

Glutathione depletion<br />

assays 48 h<br />

Sulphahydryl<br />

repletion studies.<br />

I-407, Intestinal<br />

epithelial cell<br />

line.<br />

— Rank order cytotoxicity <strong>of</strong> various metal salts in I-407 intestinal epithelial<br />

cells in terms <strong>of</strong> LC50 values—HgCl2 (32 µM) > CdCl2 (53 µM), CuCl2<br />

(156 µM) > Ti2SO4<br />

(377 µM) > Pb (NO3)2 (1.99 mM)<br />

Role <strong>of</strong> Glutathione, in the cytotoxicity <strong>of</strong> these metals by the assessment<br />

<strong>of</strong> GSH depletion by Butathionine sulfoxamine pretreatment at non<br />

cytotoxic concentration increased the toxicity <strong>of</strong> HgCl2 (5.7-fold), and<br />

CuCl2 (1.44-fold).<br />

Administration <strong>of</strong> glutathione, with either HgCl2 or CdCl2 did not protect<br />

the cells against the toxicity.<br />

N-acetyl cysteine reduced the cytotoxicity <strong>of</strong> mercury.<br />

Keogh et al. (1994)


AX5-181<br />

Table AX5-10.8. <strong>Lead</strong> and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous<br />

Compound and<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Authors<br />

Pb acetate, 0.1%, in<br />

drinking water<br />

100 mg/Pb acetate/kg<br />

b. wt.<br />

Added Pb concentration<br />

in the milk—0–80 µg/mL<br />

Pb as Pb acetate, <strong>for</strong> 0.5–<br />

10.0 µM, Zn as Zn<br />

acetate 0, 5, 10, or 50 µM<br />

Temperature variation<br />

Expts, 5 µM Pb, and<br />

incubated <strong>for</strong> 10 min at 4,<br />

22, or 37 ° C<br />

Multiple analyses at<br />

2, 30, and 60 days<br />

after Pb exposure<br />

Multiple analyses at<br />

2, 30 and 60 days<br />

Male Wistar rats — Small intestinal goblet cells are involved in Pb detoxification.<br />

Pb treatment <strong>for</strong> 30 days produces characteristic goblet cells in the<br />

intestine and Pb appears in conjunction with goblet cell membrane.<br />

Prolonged exposure to Pb more than 30 days caused silver sulphide<br />

deposition (indicative <strong>of</strong> heavy metal deposition) in the mucus droplets<br />

<strong>of</strong> cytoplasmic goblet cells.<br />

Male Wistar rats — Pb poisoning changes the ultra structure <strong>of</strong> intestine.<br />

— Adult and Infant<br />

rats (16 days)<br />

Fresh or frozen rat<br />

or Avian milk<br />

5, 10, 30 or 60 min,<br />

Simultaneously with<br />

Pb <strong>for</strong> 10 min<br />

Incubation time<br />

10 min<br />

IEC-6 normal rat<br />

intestinal<br />

epithelial cells<br />

30 days Pb exposed rat intestinal enterocytes showed numerous, small<br />

rough-membraned vesicles and prominent, dilated golgi complexes, in<br />

their cytoplasm.<br />

By 60 th day, Pb-exposed rats had a vacuolated cytoplasm and prominent<br />

golgi filled with vacuoles.<br />

— 90% <strong>of</strong> Pb in rat and bovine milk was found associated with caseine<br />

micelles regardless <strong>of</strong> whether the milk is labeled in vitro or in vivo with<br />

203 Pb. Similarly Pb in infant milk <strong>for</strong>mula was also predominantly<br />

associated with casein, however, to a much lower extent than rat and<br />

bovine milk <strong>for</strong>mulae.<br />

Pb tracer studies indicated that in infant rats, as the milk traversed through<br />

the intestine, in the collected luminal fluid, Pb was primarily associated<br />

with casein curd and remained as a nonprecipitable, nondialyzable fraction<br />

as it moved to the small intestine, indicating that Pb remains with protein<br />

fraction as it traverses through the stomach and small intestine fraction.<br />

— Pb uptake by IEC-6 cells depends on the extracellular Pb concentration.<br />

Pb transport in IEC-6 cells is time and temperature dependent, involves<br />

sulphahydryl groups, and is decreased by the presence <strong>of</strong> Zn.<br />

Tomczok et al.<br />

(1988)<br />

Tomczok et al.<br />

(1991)<br />

Beach and Henning<br />

(1988)<br />

Dekaney et al.<br />

(1997)


AX5-182<br />

Table AX5-10.8 (cont’d). <strong>Lead</strong> and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous<br />

Compound and<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Authors<br />

OECD<br />

(Organisation <strong>for</strong><br />

Economic Co-operation<br />

and Development)<br />

medium was artificially<br />

contaminated at 1, 3, 5, or<br />

10 times the Dutch<br />

intervention value <strong>of</strong><br />

530 mg/Pb/kg dry wt. Pb<br />

containing medium was<br />

presented at the apical<br />

surface <strong>of</strong> the cells in 2<br />

mL DMEM/chyme.<br />

Neutral red uptake<br />

studies had<br />

DMEM/chime with low<br />

5 µM and high 50 µM Pb<br />

content<br />

44 mg/kg/d Pb as<br />

53 mmol/L Pb acetate<br />

2.5 mg/mL Pb acetate in<br />

drinking water<br />

100 µM Pb nitrate,<br />

in vitro<br />

Cell viability<br />

studies—24 h<br />

incubation.<br />

Pb transport studies,<br />

1, 3, 5, and 24 h<br />

— Transport <strong>of</strong> bioaccessible Pb across the intestinal epithelium—In Coco-2<br />

cells exposed to artificial chime, with in 24 hrs. App. 27% <strong>of</strong> the Pb was<br />

associated with the cells and 3% were transported across the cell<br />

monolayer. Pb associated with cells showed a linear relationship with the<br />

Pb available in the system.<br />

Results indicate that only a fraction <strong>of</strong> the bioavailable Pb is transported<br />

across the intestinal epithelium.<br />

On the basis <strong>of</strong> Pb speciation in chime, It could be attributed that<br />

dissociation <strong>of</strong> labile Pb species, such as Pb phosphate, and Pb bile<br />

complexes and subsequent transport <strong>of</strong> the released free metal ions flow<br />

toward the intestinal membrane.<br />

4 wks Rat — Pb exposure significantly decreases the amplitude <strong>of</strong> contraction in rat<br />

duodenum.<br />

55 days Colonic segments<br />

taken from<br />

chronically<br />

exposed guinea<br />

pigs<br />

Duration not<br />

specified<br />

Muscle–myenteric<br />

plexus<br />

preparations <strong>of</strong><br />

distal ileum <strong>of</strong><br />

controlled animals<br />

Exposed:<br />

80 µg/dL<br />

Colonic propulsive activity as measured by the velocity <strong>of</strong> the<br />

displacement <strong>of</strong> the balloon, from the oral to the aboral end, did not get<br />

affected significantly by Pb treatment. In longitudinal muscle-myenteric<br />

plexus preparations <strong>of</strong> distal ileum, addition <strong>of</strong> Pb nitrate (100 µm) caused<br />

slight increase in cholinergic contractions.<br />

— Moderate decrease <strong>of</strong> electrically induced cholinergic contractions.<br />

Oomen et al. (2003)<br />

Karmakar and<br />

Anand (1989)<br />

Rizzi et al. (1989)


AX5-183<br />

Table AX5-10.8 (cont’d). <strong>Lead</strong> and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous<br />

Compound and<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Authors<br />

40 µM–240 µM Tri ethyl<br />

Pb added in a cumulative<br />

manner in vitro to midileal<br />

portion.<br />

a CYP—Cytochrome P-450<br />

7.5 sec–2 min Swiss mice JVI1<br />

ileum<br />

— 1. Peristaltic contractile activity <strong>of</strong> ileum as measured as a change in<br />

period duration and <strong>for</strong>ce amplitude indicated that tri ethyl Pb (TEL)<br />

concentrations <strong>of</strong>


AX5-184<br />

Table AX5-10.9. <strong>Lead</strong>, Calcium, and Vitamin D Interactions, and Intestinal Enzymes<br />

Compound and<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Authors<br />

Ca—0.5% in diet<br />

(low calcium)<br />

1.2% in diet<br />

(high calcium)<br />

Pb—0.8% in the diet<br />

as Pb chloride<br />

Ca—0.1% or 1.2% in the<br />

diet with Pb—0.1–0.8%<br />

as Pb chloride in the diet<br />

Ca—0.1–1.2%<br />

Pb—0.8%<br />

10 days White Leghorn<br />

Cockerels<br />

1 or 2 wks Leghorn<br />

Cockerels<br />

2 wks White Leghorn<br />

Cockerels<br />

— Dietary Pb affects intestinal Ca absorption in two different ways<br />

depending on the dietary Ca status.<br />

A. In chicks fed low Ca diet (0.05%), ingested Pb inhibited intestinal<br />

47<br />

Ca absorption, intestinal Calbindin D, and alkaline phosphatase<br />

synthesis in a dose dependent fashion.<br />

B. In normal calcium diets (1.2%) Pb exposure had no bearing on the<br />

intestinal Ca absorption, or Calbindin D, or Alkaline phosphatase<br />

synthesis and in fact elevated their levels at higher Pb concentrations.<br />

These results indicate that the primary effects <strong>of</strong> Pb in both cases,<br />

occur at or prior to intestinal protein synthesis involving<br />

Cholecalciferol endocrine system.<br />

— —Dietary Ca deficiency, initially<br />

(1st week) stimulates Ca absorption and Calbindin D levels regardless <strong>of</strong><br />

dietary Pb intake.<br />

—At 2 wks, this response is reversed by Pb.<br />

—Intestinal Pb absorption was enhanced by Ca deficiency initially and<br />

was inhibited by prolonged dietary Pb intake.<br />

—Intestinal Pb absorption was increased in adequate Ca situation, but<br />

only after 2 wks at the lower levels <strong>of</strong> dietary Pb.<br />

— Interactions between dietary Pb and Ca-influence on serum vitamin D<br />

levels.<br />

—Pb ingestion and Ca deficiency alone or in combination generally<br />

increased serum 1,25 (OH)2 D levels over the most <strong>of</strong> the range <strong>of</strong><br />

dietary Pb and Ca.<br />

—In severe Ca deficiency, Pb ingestion resulted in significant decreases in<br />

hormone concentration.<br />

—Similarities in response pr<strong>of</strong>iles <strong>for</strong> 1,25 ( OH)2 D, intestinal Ca<br />

absorption and Calbindin- D suggested major interactions between Pb<br />

and calcium mediated changes via circulating1,25(OH)2 D<br />

concentration.<br />

Fullmer and Rosen<br />

(1990)<br />

Fullmer (1991)<br />

Fullmer (1997)


AX5-185<br />

Table AX5-10.9 (cont’d). <strong>Lead</strong>, Calcium, and Vitamin D Interactions, and Intestinal Enzymes<br />

Compound and<br />

Concentration Duration Species Blood <strong>Lead</strong> Effects a Authors<br />

Pb, Alkaline phosphatase<br />

and Ca 2+ ATPase<br />

2.0–10.0 mM<br />

Pb, Sucrase<br />

0.5 mM–6.0 mM<br />

Pb, (-glutamyl<br />

transpeptidase1.0–10 mM<br />

Pb, Acetyl choline<br />

esterase 10.00–35.00 mM<br />

Oral Pb in Similac or<br />

apple juice adjusted <strong>for</strong><br />

attainment <strong>of</strong> blood Pb<br />

levels 35–40 µg/dL.<br />

Succimer 30 mg/kg/d<br />

204<br />

Pb 24.5 nM followed<br />

by 206 Pb 352 nM,<br />

Single dose<br />

a CYP—Cytochrome P-450<br />

Incubation time not<br />

specified<br />

Administered from<br />

8th day post partum,<br />

until age 26 wks<br />

Two successive<br />

19 days at age 53 wks<br />

and 65 wks<br />

Administered<br />

immediately be<strong>for</strong>e<br />

chelation<br />

Male Albino rats Pb inhibited the activity <strong>of</strong> several intestinal brush border enzymes such as<br />

Ca 2+ - ATPase, Sucrase, (-glutamyl-transpeptidase and acetyl choline<br />

esterase with the exception <strong>of</strong> alkaline phosphatase. Inhibition <strong>of</strong> Ca 2+ -<br />

ATPase was competitive and that <strong>of</strong> the other enzymes is by noncompetitive<br />

means.<br />

Female infant<br />

Rhesus Monkeys<br />

Pb-exposed:<br />

35–40 µg/dL<br />

Effect <strong>of</strong> oral succimer chelation on the Gastro intestinal absorption and<br />

the whole body retention <strong>of</strong> Pb<br />

Radio isotope Pb tracer technique<br />

Succimer significantly reduced Gastro intestinal absorption <strong>of</strong> Pb and<br />

increased urinary excretion <strong>of</strong> Pb<br />

The initial decrease in whole body Pb by 10% was over come when<br />

majority <strong>of</strong> administered tracer was retained in the body after 5 days <strong>of</strong><br />

treatment.<br />

Gupta et al. (1994)<br />

Cremin et al. (2001)


ANNEX TABLES AX5-11<br />

AX5-186


AX5-187<br />

Source Organ Species<br />

Table AX5-11.1. <strong>Lead</strong>-binding Proteins<br />

Goyer (1968) Kidney Rat Intranuclear Pb inclusion<br />

bodies<br />

Goyer et al. (1970a,b) Kidney Rat Pb is concentrated in the<br />

intranuclear inclusion body<br />

Choie and Richter (1972) Kidney Rat Initial inclusion bodies in<br />

cytoplasm<br />

Moore et al. (1973) Kidney Rat Protein in inclusion bodies is<br />

acidic, with high levels <strong>of</strong><br />

aspartic a, glutamic a, glycine<br />

and cystine<br />

Moore and Goyer (1974) Kidney Rat Inclusion body<br />

protein is<br />

27.5 kDa<br />

Shelton and Egle (1982) Kidney Rat Inclusion body is<br />

32 kDa with pI<br />

<strong>of</strong> 6.3<br />

Egle and Shelton (1986) Brain Rat, mouse,<br />

dog, guinea<br />

pig, and<br />

chicken<br />

Oskarsson et al. (1982) Kidney<br />

cytosol and<br />

brain<br />

Mistry et al. (1985) Kidney<br />

cytosol<br />

Fowler and DuVal (1991) Kidney<br />

cytosol<br />

Molecular<br />

Weight Protein Properties Inducible Separation Technique<br />

Yes<br />

Yes<br />

Yes<br />

Yes<br />

Yes Acrylamide gel electrophoresis<br />

Named p32/6.3 Yes Two-dimensional gel electrophoresis<br />

p32/6.3 found No<br />

Rat 11.5 and 63 kDa No<br />

Rat 11.5 kDa, 63 kDa,<br />

> 200 kDa<br />

Respective Kd values: 13,<br />

40, 123 nM<br />

Rat Cleavage product <strong>of</strong> alpha-2<br />

microglobulin<br />

No<br />

203 Pb binding followed by Sephadex<br />

G-75 or G-200 chromatography, then<br />

SDS-PAGE<br />

203 Pb binding followed by Sepharose-<br />

6B column chromatography<br />

No Chromatography followed by reverse<br />

phase HPLC, then production <strong>of</strong><br />

antibodies Kd 10–8 M


AX5-188<br />

Source Organ Species<br />

Table AX5-11.1 (cont’d). <strong>Lead</strong>-binding Proteins<br />

Molecular<br />

Weight Protein Properties Inducible Separation Technique<br />

Smith et al. (1998) Kidney cortex Human 9 kDa and 5 kDa ACBP and thymosin B4 No Sephadex G-75 fractions


AX5-189<br />

Source Organ Species<br />

Church et al. (1993a) RBC Human Pb<br />

workers, one<br />

asymptomatic<br />

and one<br />

symptomatic<br />

Church et al. (1993b) RBC Human Pb<br />

workers<br />

Xie et al. (1998) RBC Human Pb<br />

workers<br />

Goering and Fowler,<br />

(1987a)<br />

Goering and Fowler,<br />

(1987b)<br />

Qu et al. (2002);<br />

Waalkes et al. (2004)<br />

Table AX5-11.1 (cont’d). <strong>Lead</strong>-binding Proteins<br />

Molecular<br />

Weight Protein Properties Inducible Separation Technique<br />

6–7 kDa First pt had 67% <strong>of</strong> RBC Pb<br />

bound to protein. Second pt<br />

had 22% <strong>of</strong> RBC Pb in<br />

protein<br />

5, 7 and 12 kDa,<br />

pI 4.7–4.9<br />

240 ~ 260 kDa,<br />


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October 2006<br />

<strong>EPA</strong>/600/R-05/144bF<br />

<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong> <strong>of</strong> <strong>II</strong>


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong><br />

National Center <strong>for</strong> Environmental Assessment-RTP Division<br />

Office <strong>of</strong> Research and Development<br />

U.S. Environmental Protection Agency<br />

Research Triangle Park, NC<br />

<strong>EPA</strong>/600/R-05/144bF<br />

October 2006


PREFACE<br />

National Ambient <strong>Air</strong> <strong>Quality</strong> Standards (NAAQS) are promulgated by the United States<br />

Environmental Protection Agency (<strong>EPA</strong>) to meet requirements set <strong>for</strong>th in Sections 108 and 109<br />

<strong>of</strong> the U.S. Clean <strong>Air</strong> Act. Those two Clean <strong>Air</strong> Act sections require the <strong>EPA</strong> Administrator<br />

(1) to list widespread air pollutants that reasonably may be expected to endanger public health or<br />

welfare; (2) to issue air quality criteria <strong>for</strong> them that assess the latest available scientific<br />

in<strong>for</strong>mation on nature and effects <strong>of</strong> ambient exposure to them; (3) to set “primary” NAAQS to<br />

protect human health with adequate margin <strong>of</strong> safety and to set “secondary” NAAQS to protect<br />

against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade<br />

materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS<br />

<strong>for</strong> a given listed pollutant or class <strong>of</strong> pollutants.<br />

<strong>Lead</strong> was first listed in the mid-1970’s as a “criteria air pollutant” requiring NAAQS<br />

regulation. The scientific in<strong>for</strong>mation pertinent to Pb NAAQS development available at the time<br />

was assessed in the <strong>EPA</strong> document <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>; published in 1977. Based on<br />

the scientific assessments contained in that 1977 lead air quality criteria document (1977 <strong>Lead</strong><br />

AQCD), <strong>EPA</strong> established a 1.5 µg/m 3 (maximum quarterly calendar average) Pb NAAQS in<br />

1978.<br />

To meet Clean <strong>Air</strong> Act requirements noted above <strong>for</strong> periodic review <strong>of</strong> criteria and<br />

NAAQS, new scientific in<strong>for</strong>mation published since the 1977 <strong>Lead</strong> AQCD was later assessed in<br />

a revised <strong>Lead</strong> AQCD and Addendum published in 1986 and in a Supplement to the 1986<br />

AQCD/Addendum published by <strong>EPA</strong> in 1990. A 1990 <strong>Lead</strong> Staff Paper, prepared by <strong>EPA</strong>’s<br />

Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards (OPQPS), drew upon key findings and conclusions<br />

from the 1986 <strong>Lead</strong> AQCD/Addendum and 1990 Supplement (as well as other OAQPSsponsored<br />

lead exposure/risk analyses) in posing options <strong>for</strong> the <strong>EPA</strong> Administrator to consider<br />

with regard to possible revision <strong>of</strong> the Pb NAAQS. However, <strong>EPA</strong> chose not to revise the Pb<br />

NAAQS at that time. Rather, as part <strong>of</strong> implementing a broad 1991 U.S. <strong>EPA</strong> Strategy <strong>for</strong><br />

Reducing <strong>Lead</strong> Exposure, the Agency focused primarily on regulatory and remedial clean-up<br />

ef<strong>for</strong>ts to reduce Pb exposure from a variety <strong>of</strong> non-air sources that posed more extensive public<br />

health risks, as well as other actions to reduce air emissions.<br />

<strong>II</strong>-iii


The purpose <strong>of</strong> this revised <strong>Lead</strong> AQCD is to critically assess the latest scientific<br />

in<strong>for</strong>mation that has become available since the literature assessed in the 1986 <strong>Lead</strong><br />

AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new<br />

in<strong>for</strong>mation useful in evaluating health and environmental effects <strong>of</strong> ambient air lead exposures.<br />

This includes discussion in this document <strong>of</strong> in<strong>for</strong>mation regarding: the nature, sources,<br />

distribution, measurement, and concentrations <strong>of</strong> lead in the environment; multimedia lead<br />

exposure (via air, food, water, etc.) and biokinetic modeling <strong>of</strong> contributions <strong>of</strong> such exposures<br />

to concentrations <strong>of</strong> lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,<br />

as key indices <strong>of</strong> lead exposure).; characterization <strong>of</strong> lead health effects and associated exposureresponse<br />

relationships; and delineation <strong>of</strong> environmental (ecological) effects <strong>of</strong> lead. This final<br />

version <strong>of</strong> the revised <strong>Lead</strong> AQCD mainly assesses pertinent literature published or accepted <strong>for</strong><br />

publication through December 2005.<br />

The First External Review Draft (dated December 2005) <strong>of</strong> the revised <strong>Lead</strong> AQCD<br />

underwent public comment and was reviewed by the Clean <strong>Air</strong> Scientific Advisory Committee<br />

(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public<br />

comments and CASAC recommendations received were taken into account in making<br />

appropriate revisions and incorporating them into a Second External Review Draft (dated May,<br />

2006) which was released <strong>for</strong> further public comment and CASAC review at a public meeting<br />

held June 28-29, 2006. In addition, still further revised drafts <strong>of</strong> the Integrative Synthesis<br />

chapter and the Executive Summary were then issued and discussed during an August 15, 2006<br />

CASAC teleconference call. Public comments and CASAC advice received on these latter<br />

materials, as well as Second External Review Draft materials, were taken into account in making<br />

and incorporating further revisions into this final version <strong>of</strong> this <strong>Lead</strong> AQCD, which is being<br />

issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present<br />

document provide inputs to an associated <strong>Lead</strong> Staff Paper prepared by <strong>EPA</strong>’s Office <strong>of</strong> <strong>Air</strong><br />

<strong>Quality</strong> Planning and Standards (OAQPS), which poses options <strong>for</strong> consideration by the <strong>EPA</strong><br />

Administrator with regard to proposal and, ultimately, promulgation <strong>of</strong> decisions on potential<br />

retention or revision, as appropriate, <strong>of</strong> the current Pb NAAQS.<br />

Preparation <strong>of</strong> this document has been coordinated by staff <strong>of</strong> <strong>EPA</strong>’s National Center <strong>for</strong><br />

Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific<br />

staff, together with experts from academia, contributed to writing <strong>of</strong> document chapters. Earlier<br />

<strong>II</strong>-iv


drafts <strong>of</strong> document materials were reviewed by scientists from other <strong>EPA</strong> units and by non-<strong>EPA</strong><br />

experts in several public peer consultation workshops held by <strong>EPA</strong> in July/August 2005.<br />

NCEA acknowledges the valuable contributions provided by authors, contributors, and<br />

reviewers and the diligence <strong>of</strong> its staff and contractors in the preparation <strong>of</strong> this document. The<br />

constructive comments provided by public commenters and CASAC that served as valuable<br />

inputs contributing to improved scientific and editorial quality <strong>of</strong> the document are also<br />

acknowledged by NCEA.<br />

DISCLAIMER<br />

Mention <strong>of</strong> trade names or commercial products in this document does not constitute<br />

endorsement or recommendation <strong>for</strong> use.<br />

.<br />

<strong>II</strong>-v


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(Second External Review Draft)<br />

VOLUME I<br />

EXECUTIVE SUMMARY .........................................................................................................E-1<br />

1. INTRODUCTION ........................................................................................................... 1-1<br />

2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD.......................................... 2-1<br />

3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED<br />

ENVIRONMENTAL CONCENTRATIONS.................................................................. 3-1<br />

4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD<br />

BURDEN IN HUMANS.................................................................................................. 4-1<br />

5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS<br />

AND IN VITRO TEST SYSTEMS................................................................................. 5-1<br />

6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS<br />

ASSOCIATED WITH LEAD EXPOSURE.................................................................... 6-1<br />

7. ENVIRONMENTAL EFFECTS OF LEAD ................................................................... 7-1<br />

8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH<br />

EFFECTS INFORMATION............................................................................................ 8-1<br />

VOLUME <strong>II</strong><br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS)..................................................... AX4-1<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN<br />

LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS)................ AX5-1<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH<br />

EFFECTS ASSOCIATED WITH LEAD EXPOSURE)................................. AX6-1<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD).................................. AX7-1<br />

<strong>II</strong>-vi


Table <strong>of</strong> Contents<br />

Page<br />

PREFACE......................................................................................................................................iii<br />

DISCLAIMER ................................................................................................................................ v<br />

List <strong>of</strong> Tables ...............................................................................................................................viii<br />

Authors, Contributors, and Reviewers........................................................................................... xi<br />

U.S. Environmental Protection Agency Project Team <strong>for</strong> Development<br />

<strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>............................................................................................. xvii<br />

U.S. Environmental Protection Agency Science Advisory Board (SAB)<br />

Staff Office Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)......................................... xix<br />

Abbreviations and Acronyms ...................................................................................................... xxi<br />

AX6. CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN<br />

HEALTH EFFECTS ASSOCIATED WITH LEAD EXPOSURE ......................... AX6-1<br />

ANNEX TABLES AX6-2 ....................................................................................... AX6-2<br />

ANNEX TABLES AX6-3 ..................................................................................... AX6-29<br />

ANNEX TABLES AX6-4 ..................................................................................... AX6-69<br />

ANNEX TABLES AX6-5 ................................................................................... AX6-129<br />

ANNEX TABLES AX6-6 ................................................................................... AX6-168<br />

ANNEX TABLES AX6-7 ................................................................................... AX6-182<br />

ANNEX TABLES AX6-8 ................................................................................... AX6-206<br />

ANNEX TABLES AX6-9 ................................................................................... AX6-220<br />

REFERENCES .................................................................................................... AX6-260<br />

<strong>II</strong>-vii


List <strong>of</strong> Tables<br />

Number Page<br />

AX6-2.1 Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in<br />

Children............................................................................................................ AX6-3<br />

AX6-2.2 Meta- and Pooled-Analyses <strong>of</strong> Neurocognitive Ability in Children ............... AX6-9<br />

AX6-2.3 Cross-Sectional Studies <strong>of</strong> Neurocognitive Ability in Children.................... AX6-11<br />

AX6-2.4 Effects <strong>of</strong> <strong>Lead</strong> on Academic Achievement in Children ............................... AX6-14<br />

AX6-2.5 Effects <strong>of</strong> <strong>Lead</strong> on Specific Cognitive Abilities in Children —<br />

Attention/Executive Functions, Learning, and Visual-spatial Skills............. AX6-17<br />

AX6-2.6 Effects <strong>of</strong> <strong>Lead</strong> on Disturbances in Behavior, Mood, and Social<br />

Conduct in Children....................................................................................... AX6-19<br />

AX6-2.7 Effects <strong>of</strong> <strong>Lead</strong> on Sensory Acuities in Children........................................... AX6-23<br />

AX6-2.8 Effects <strong>of</strong> <strong>Lead</strong> on Neuromotor Function in Children................................... AX6-24<br />

AX6-2.9 Effects <strong>of</strong> <strong>Lead</strong> on Direct Measures <strong>of</strong> Brain Anatomical<br />

Development and Activity in Children.......................................................... AX6-25<br />

AX6-2.10 Reversibility <strong>of</strong> <strong>Lead</strong>-related Deficits in Children......................................... AX6-27<br />

AX6-3.1 Neurobehavioral Effects Associated with Environmental<br />

<strong>Lead</strong> Exposure in Adults................................................................................ AX6-30<br />

AX6-3.2 Symptoms Associated with Occupational <strong>Lead</strong> Exposure in Adults............. AX6-33<br />

AX6-3.3 Neurobehavioral Effects Associated with Occupational <strong>Lead</strong><br />

Exposure in Adults......................................................................................... AX6-36<br />

AX6-3.4 Meta-analyses <strong>of</strong> Neurobehavioral Effects with Occupational<br />

<strong>Lead</strong> Exposure in Adults................................................................................ AX6-49<br />

AX6-3.5 Neurophysiological Function and Occupational <strong>Lead</strong><br />

Exposure in Adults......................................................................................... AX6-51<br />

AX6-3.6 Evoked Potentials and Occupational <strong>Lead</strong> Exposure in Adults..................... AX6-56<br />

AX6-3.7 Postural Stability, Autonomic Testing, Electroencephalogram,<br />

Hearing Thresholds, and Occupational <strong>Lead</strong> Exposure in Adults................. AX6-59<br />

<strong>II</strong>-viii


List <strong>of</strong> Tables<br />

(cont’d)<br />

Number Page<br />

AX6-3.8 Occupational Exposure to Organolead and Inorganic <strong>Lead</strong> in Adults .......... AX6-63<br />

AX6-3.9 Other Neurological Outcomes Associated with <strong>Lead</strong> Exposure in Adults.... AX6-66<br />

AX6-4.1 Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population........................................... AX6-70<br />

AX6-4.2 Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population.................................. AX6-81<br />

AX6-4.3 Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population .......................................... AX6-104<br />

AX6-4.4 Renal Effects <strong>of</strong> <strong>Lead</strong> on Mortality ............................................................. AX6-120<br />

AX6-4.5 Renal Effects <strong>of</strong> <strong>Lead</strong> in Children ............................................................... AX6-122<br />

AX6-5.1 Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension ................................. AX6-130<br />

AX6-5.2 Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Morbidity ............................................. AX6-159<br />

AX6-5.3 Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Mortality............................................... AX6-162<br />

AX6-5.4 Cardiovascular Effects <strong>of</strong> <strong>Lead</strong> on Children................................................ AX6-166<br />

AX6-6.1 Placental Transfer <strong>of</strong> <strong>Lead</strong> from Mother to Fetus........................................ AX6-169<br />

AX6-6.2 <strong>Lead</strong> Exposure and Male Reproduction: Semen <strong>Quality</strong>............................ AX6-174<br />

AX6-6.3 <strong>Lead</strong> Exposure and Male Reproduction: Time to Pregnancy ..................... AX6-178<br />

AX6-6.4 <strong>Lead</strong> Exposure and Male Reproduction: Reproductive History................. AX6-180<br />

AX6-7.1 Recent Studies <strong>of</strong> <strong>Lead</strong> Exposure and Genotoxicity.................................... AX6-183<br />

AX6-7.2 Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer ........................... AX6-186<br />

AX6-7.3 Key Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer in the General Population........ AX6-192<br />

AX6-7.4 Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer ............................................... AX6-194<br />

AX6-8.1 Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Children ....................................... AX6-207<br />

AX6-8.2 Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults........................................... AX6-211<br />

<strong>II</strong>-ix


List <strong>of</strong> Tables<br />

(cont’d)<br />

Number Page<br />

AX6-9.1 Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Children ................................... AX6-221<br />

AX6-9.2 Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults....................................... AX6-223<br />

AX6-9.3 Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Children ............................... AX6-231<br />

AX6-9.4 Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults................................... AX6-234<br />

AX6-9.5 Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Children................................. AX6-241<br />

AX6-9.6 Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults.................................... AX6-243<br />

AX6-9.7 Effects <strong>of</strong> <strong>Lead</strong> on the Hepatic System in Children and Adults .................. AX6-251<br />

AX6-9.8 Effects <strong>of</strong> <strong>Lead</strong> on the Gastrointestinal System........................................... AX6-253<br />

AX6-9.9 Effects <strong>of</strong> <strong>Lead</strong> on Bone and Teeth in Children and Adults........................ AX6-255<br />

AX6-9.10 Effects <strong>of</strong> <strong>Lead</strong> on Ocular Health in Children and Adults........................... AX6-258<br />

<strong>II</strong>-x


Authors, Contributors, and Reviewers<br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS)<br />

Chapter Managers/Editors<br />

Dr. James Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principal Authors<br />

Dr. Brian Gulson—Graduate School <strong>of</strong> the Environment, Macquarie University<br />

Sydney, NSW 2109, Australia<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS<br />

AND LABORATORY ANIMALS)<br />

Chapter Managers/Editors<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xi


Principal Authors<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Stephen Lasley—Dept. <strong>of</strong> Biomedical and Therapeutic Sciences, Univ. <strong>of</strong> Illinois College <strong>of</strong><br />

Medicine, PO Box 1649, Peoria, IL 61656<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001<br />

Dr. N.D. Vaziri—Division <strong>of</strong> Nephrology and Hypertension, University <strong>of</strong> Cali<strong>for</strong>nia – Irvine<br />

Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868<br />

Dr. John Pierce Wise, Sr.—Maine Center <strong>for</strong> Toxicology and Environmental Health,<br />

Department <strong>of</strong> Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME<br />

04104-9300<br />

Dr. Harvey C. Gonick—David Geffen School <strong>of</strong> Medicine, University <strong>of</strong> Cali<strong>for</strong>nia at<br />

Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049<br />

Dr. Gene E. Watson—University <strong>of</strong> Rochester Medical Center, Box 705, Rochester, NY 14642<br />

Dr. Rodney Dietert—Institute <strong>for</strong> Comparative and Environmental Toxicology, College <strong>of</strong><br />

Veterinary Medicine, Cornell University, Ithaca, NY 14853<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David A. Lawrence—Dept <strong>of</strong> Environmental and Clinical Immunology, Empire State Plaza<br />

P.O. Box 509, Albany, NY 12201<br />

<strong>II</strong>-xii


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Michael J. McCabe, Jr.—Dept <strong>of</strong> Environmental Medicine, University <strong>of</strong> Rochester,<br />

575 Elmwood Avenue, Rochester, NY 14642<br />

Dr. Theodore I. Lidsky—New York State Institute <strong>for</strong> Basic Research, 1050 Forest RD,<br />

Staten Island, NY 10314<br />

Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001<br />

Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD<br />

EXPOSURE EFFECTS)<br />

Chapter Managers/Editors<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xiii


Principal Authors<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. David Bellinger—Children’s Hospital, Farley Basement, Box 127, 300 Longwood Avenue,<br />

Boston, MA 02115<br />

Dr. Margit Bleecker—Center <strong>for</strong> Occupational and Environmental Neurology, 2 Hamill Road,<br />

Suite 225, Baltimore, MD 21210<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.<br />

Akron, NY 14001<br />

Dr. Kim Dietrich—University <strong>of</strong> Cincinnati College <strong>of</strong> Medicine, 3223 Eden Avenue,<br />

Kettering Laboratory, Room G31, Cincinnati, OH 45267<br />

Dr. Pam Factor-Litvak—Columbia University Mailman School <strong>of</strong> Public Health,<br />

722 West 168th Street, Room 1614, New York, NY 10032<br />

Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713<br />

Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Mérida, Yucatán, México & National Institute<br />

<strong>of</strong> Public Health, Cuernavaca, Morelos, Mexico<br />

Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School <strong>of</strong> Public Health<br />

& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112<br />

Dr. Kyle Steenland—Rollins School <strong>of</strong> Public Health, Emory University, 1518 Clifton Road,<br />

Room 268, Atlanta, GA 30322<br />

Dr. Virginia Weaver—Johns Hopkins Bloomberg School <strong>of</strong> Public Health, 615 North Wolfe<br />

Street, Room 7041, Baltimore, MD 21205<br />

Contributors and Reviewers<br />

Dr. J. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Kazuhiko Ito—Nelson Institute <strong>of</strong> Environmental Medicine, New York University School <strong>of</strong><br />

Medicine, Tuxedo, NY 10987<br />

<strong>II</strong>-xiv


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Kathryn Mahaffey—Office <strong>of</strong> Prevention, Pesticides and Toxic Substances,<br />

U.S. Environmental Protection Agency, Washington, DC 20460<br />

Dr. Karen Martin—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Chapter Manager/Editor<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principle Authors<br />

Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,<br />

Ontario, L5N 3C9 Canada<br />

Dr. James Kaste—Department <strong>of</strong> Earth Sciences, Dartmouth College, 352 Main Street,<br />

Hanover, NH 03755<br />

Dr. John Drexler—Department <strong>of</strong> Geological Sciences, University <strong>of</strong> Colorado,<br />

1216 Gillespie Drive, Boulder, CO 80305<br />

Dr. Chris Johnson—Department <strong>of</strong> Civil and Environmental Engineering, Syracuse University,<br />

365 Link Hall, Syracuse, NY 13244<br />

Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321<br />

<strong>II</strong>-xv


Principle Authors<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Dwayne Moore—Cantox Environmental, Inc., 1550A Laperriere Avenue, Suite 103,<br />

Ottawa, Ontario, K1Z 7T2 Canada<br />

Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004<br />

Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,<br />

Winchester, MA 01890<br />

Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place,<br />

Suite 202, Winchester, MA 01890<br />

Contributors and Reviewers<br />

Dr. Jerome Nriagu—Department <strong>of</strong> Environmental Health Sciences, 109 South Observatory,<br />

University <strong>of</strong> Michigan, Ann Arbor, MI 48109<br />

Dr. Judith Weis—Department <strong>of</strong> Biology, Rutgers University, Newark, NJ 07102<br />

Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Ginger Tennant—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Gail Lacey—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental Protection<br />

Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xvi


Executive Direction<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

Dr. Lester D. Grant (Director)—National Center <strong>for</strong> Environmental Assessment-RTP Division,<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Scientific Staff<br />

Dr. Lori White (<strong>Lead</strong> Team <strong>Lead</strong>er)—National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. James S. Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Robert Elias—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Dr. Brooke Hemming—National Center <strong>for</strong> Environmental Assessment (B243-01), U.S.<br />

Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Anuradha Muldipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Mary Ross— National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xvii


Technical Support Staff<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(cont’d)<br />

Mr. Douglas B. Fennell—Technical In<strong>for</strong>mation Specialist, National Center <strong>for</strong> Environmental<br />

Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC<br />

27711 (Retired)<br />

Ms. Emily R. Lee—Management Analyst, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Diane H. Ray—Program Specialist, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Donna Wicker—Administrative Officer, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Mr. Richard Wilson—Clerk, National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Document Production Staff<br />

Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Mr. John A. Bennett—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,<br />

Suite 1450, McLean, VA 22102<br />

Ms. Sandra L. Hughey—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards<br />

Mill Road, Suite 201, Raleigh, NC 27607<br />

Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

<strong>II</strong>-xviii


Chair<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,<br />

Albuquerque, NM<br />

Members<br />

Dr. Joshua Cohen—Faculty, Center <strong>for</strong> the Evaluation <strong>of</strong> Value and Risk, Institute <strong>for</strong> Clinical<br />

Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA<br />

Dr. Deborah Cory-Slechta—Director, University <strong>of</strong> Medicine and Dentistry <strong>of</strong> New Jersey and<br />

Rutgers State University, Piscataway, NJ<br />

Dr. Ellis Cowling*—University Distinguished Pr<strong>of</strong>essor-at-Large, North Carolina State<br />

University, Colleges <strong>of</strong> Natural Resources and Agriculture and Life Sciences, North Carolina<br />

State University, Raleigh, NC<br />

Dr. James D. Crapo [M.D.]*—Pr<strong>of</strong>essor, Department <strong>of</strong> Medicine, National Jewish Medical and<br />

Research Center, Denver, CO<br />

Dr. Bruce Fowler—Assistant Director <strong>for</strong> Science, Division <strong>of</strong> Toxicology and Environmental<br />

Medicine, Office <strong>of</strong> the Director, Agency <strong>for</strong> Toxic Substances and Disease Registry, U.S.<br />

Centers <strong>for</strong> Disease Control and Prevention (ATSDR/CDC), Chamblee, GA<br />

Dr. Andrew Friedland—Pr<strong>of</strong>essor and Chair, Environmental Studies Program, Dartmouth<br />

College, Hanover, NH<br />

Dr. Robert Goyer [M.D.]—Emeritus Pr<strong>of</strong>essor <strong>of</strong> Pathology, Faculty <strong>of</strong> Medicine, University <strong>of</strong><br />

Western Ontario (Canada), Chapel Hill, NC<br />

Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO<br />

Dr. Bruce Lanphear [M.D.]—Sloan Pr<strong>of</strong>essor <strong>of</strong> Children’s Environmental Health, and the<br />

Director <strong>of</strong> the Cincinnati Children’s Environmental Health Center at Cincinnati Children’s<br />

Hospital Medical Center and the University <strong>of</strong> Cincinnati, Cincinnati, OH<br />

Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (<strong>US</strong>GS),<br />

Menlo Park, CA<br />

<strong>II</strong>-xix


Members<br />

(cont’d)<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

(cont’d)<br />

Dr. Frederick J. Miller*—Consultant, Cary, NC<br />

Dr. Paul Mushak—Principal, PB Associates, and Visiting Pr<strong>of</strong>essor, Albert Einstein College <strong>of</strong><br />

Medicine (New York, NY), Durham, NC<br />

Dr. Michael Newman—Pr<strong>of</strong>essor <strong>of</strong> Marine Science, School <strong>of</strong> Marine Sciences, Virginia<br />

Institute <strong>of</strong> Marine Science, College <strong>of</strong> William & Mary, Gloucester Point, VA<br />

Mr. Richard L. Poirot*—Environmental Analyst, <strong>Air</strong> Pollution Control Division, Department <strong>of</strong><br />

Environmental Conservation, Vermont Agency <strong>of</strong> Natural Resources, Waterbury, VT<br />

Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA<br />

Dr. Joel Schwartz—Pr<strong>of</strong>essor, Environmental Health, Harvard University School <strong>of</strong> Public<br />

Health, Boston, MA<br />

Dr. Frank Speizer [M.D.]*—Edward Kass Pr<strong>of</strong>essor <strong>of</strong> Medicine, Channing Laboratory,<br />

Harvard Medical School, Boston, MA<br />

Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,<br />

Moscow, ID<br />

Dr. Barbara Zielinska*—Research Pr<strong>of</strong>essor, Division <strong>of</strong> Atmospheric Science, Desert Research<br />

Institute, Reno, NV<br />

SCIENCE ADVISORY BOARD STAFF<br />

Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,<br />

Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)<br />

(Physical/Courier/FedEx Address: Fred A. Butterfield, <strong>II</strong>I, <strong>EPA</strong> Science Advisory Board Staff<br />

Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,<br />

DC 20004, Telephone: 202-343-9994)<br />

*Members <strong>of</strong> the statutory Clean <strong>Air</strong> Scientific Advisory Committee (CASAC) appointed by the<br />

U.S. <strong>EPA</strong> Administrator<br />

<strong>II</strong>-xx


Abbreviations and Acronyms<br />

αFGF α-fibroblast growth factor<br />

AA arachidonic acid<br />

AAL active avoidance learning<br />

AAS atomic absorption spectroscopy<br />

ABA β-aminoisobutyric acid<br />

ACBP Achenbach Child Behavior Pr<strong>of</strong>ile<br />

ACE angiotensin converting enzyme<br />

ACh acetylcholine<br />

AChE acetylcholinesterase<br />

ACR acute-chronic ratio<br />

AD adult<br />

ADC analog digital converter<br />

ADP adenosine diphosphate<br />

AE anion exchange<br />

AEA N-arachidonylethanolamine<br />

AFC antibody <strong>for</strong>ming cells<br />

2-AG 2-arachidonylglycerol<br />

A horizon uppermost layer <strong>of</strong> soil (litter and humus)<br />

AHR aryl hydrocarbon receptor<br />

AI angiotensin I<br />

ALA ∗-aminolevulinic acid<br />

ALAD ∗-aminolevulinic acid dehydratase<br />

ALAS aminolevulinic acid synthetase<br />

ALAU urinary δ-aminolevulinic acid<br />

ALD aldosterone<br />

ALS amyotrophic lateral sclerosis<br />

ALT alanine aminotransferase<br />

ALWT albumin weight<br />

AMEM Alpha Minimal Essential Medium<br />

AMP adenosine monophosphate<br />

ANCOVA analysis <strong>of</strong> covariance<br />

ANF atrial natriuretic factor<br />

Ang <strong>II</strong> angiotensin <strong>II</strong><br />

<strong>II</strong>-xxi


ANOVA analysis <strong>of</strong> variance<br />

ANP atrial natriuretic peptide<br />

AP alkaline phosphatase<br />

AP-1 activated protein-1<br />

ApoE apolipoprotein E<br />

AQCD <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> Document<br />

Arg arginine<br />

AS52 cells derived from the CHO cell line<br />

ASGP-R aceyl glycoprotein receptor<br />

AST aspartate aminotransferase<br />

ASV anode stripping voltammetry<br />

3-AT 3-aminotriazole; 3-amino triazide<br />

ATP adenosine triphosphate<br />

ATP1A2 sodium-potassium adenosine triphosphase α2<br />

ATPase adenosine triphosphatase<br />

ATSDR Agency <strong>for</strong> Toxic Substances and Disease Research<br />

AVCD atrioventricular conduction deficit<br />

AVS acid volatile sulfide<br />

AWQC ambient water quality criteria<br />

∃ beta-coefficient; slope <strong>of</strong> an equation<br />

∃FGF ∃-fibroblast growth factor<br />

17∃–HS 17∃-hydroxysteriod<br />

3∃-HSD 3∃-hydroxysteriod dehydrogenase<br />

17∃-HSDH 17∃-hydroxysteriod dehydrogenase<br />

6∃-OH-cortisol 6-∃-hydroxycortisol<br />

B both<br />

BAEP brainstem auditory-evoked potentials<br />

BAER brainstem auditory-evoked responses<br />

BAF bioaccumulation factor<br />

B cell B lymphocyte<br />

BCFs bioconcentration factors<br />

BCS bovine calf serum<br />

BDNF brain derived neurotrophic factor<br />

BDWT body weight changes<br />

BEI biological exposure index<br />

<strong>II</strong>-xxii


BFU-E blood erythroid progenitor<br />

BLL blood lead level<br />

BLM biotic ligand model<br />

BM basement membrane<br />

BMI body mass index<br />

BDNF brain-derived neurotrophic factor<br />

BOTMP Bruinicks-Oseretsky Test <strong>of</strong> Motor Pr<strong>of</strong>iciency<br />

BP blood pressure<br />

BPb blood lead concentration<br />

BSA bovine serum albumin<br />

BSI Brief Symptom Inventory<br />

BTQ Boston Teacher Questionnaire<br />

BUN blood urea nitrogen<br />

bw, b. wt., BW body weight<br />

C3H10T/12 mouse embryo cell line<br />

C3, C4 complement proteins<br />

CA chromosome aberration<br />

CA3 cornu ammonis 3 region <strong>of</strong> hippocampus<br />

45<br />

Ca calcium-45 radionuclide<br />

Ca-ATP calcium-dependent adenosine triphosphate<br />

Ca-ATPase calcium-dependent adenosine triphosphatase<br />

CaCO3<br />

calcium carbonate<br />

CaEDTA calcium disodium ethylenediaminetetraacetic acid<br />

CAL calcitonin<br />

CaM calmodulin<br />

Ca-Mg-ATPase calcium-magnesium-dependent adenosine triphosphatase<br />

cAMP cyclic adenosinemonophosphate<br />

CaNa2 EDTA calcium disodium ethylenediaminetetraacetic acid<br />

CANTAB Cambridge Neuropsychological Testing Automated Battery<br />

CAT catalase; Cognitive Abilities Test<br />

CBCL Achenbach Child Behavior Checklist<br />

CBCL-T Total Behavior Problem Score<br />

CBL cumulative blood lead<br />

CBLI cumulative blood lead index<br />

CCB cytochalasin B<br />

<strong>II</strong>-xxiii


CCD charge-coupled device<br />

CCE Coordination Center <strong>for</strong> Effects<br />

CCL carbon tetrachloride<br />

CCS cosmic calf serum<br />

C-CVRSA<br />

coefficient <strong>of</strong> component variance <strong>of</strong> respiratory sinus arrhythmia<br />

Cd cadmium<br />

109 Cd cadmium-109 radionuclide<br />

CdU urinary cadmium<br />

CEC<br />

cation exchange capacity<br />

CESD, CES-D Center <strong>for</strong> Epidemiologic Studies Depression (scale)<br />

GFAP glial fibrillary acidic protein<br />

CFU-E colony <strong>for</strong>ming unit blood-erythroid progenitor (cell count)<br />

CFU-GEMM colony <strong>for</strong>ming unit blood-pluripotent progenitor (cell count)<br />

CFU-GM blood granulocyte/macrophage progenitor (cell count)<br />

cGMP cyclic guanosine-3',5'-monophosphate<br />

ChAT choline acetyltransferase<br />

CHD coronary heart disease<br />

CHO Chinese hamster ovary cell line<br />

CI confidence interval<br />

CLE-SV competitive ligand-exchange/stripping voltammetry<br />

CLRTAP Convention on Long-Range Transboundary <strong>of</strong> <strong>Air</strong> Pollution<br />

CLS Cincinnati <strong>Lead</strong> Study<br />

CMC criterion maximum concentration<br />

CMI cell-mediated immunity<br />

CNS central nervous system<br />

COH cation-osmotic hemolysis<br />

ConA concanavalin A<br />

COR cortisol<br />

CoTx cotreatment<br />

COX-2 cyclooxygenase-2<br />

CP coproporphryn<br />

CPT current perception threshold<br />

cr creatinine<br />

CRAC calcium release activated calcium reflux<br />

CREB cyclic AMP-response element binding protein<br />

<strong>II</strong>-xxiv


CRF chronic renal failure<br />

CRI chronic renal insufficiency<br />

CSF cerebrospinal fluid<br />

CuZn-SOD copper and zinc-dependent superoxide dismutase<br />

CV conduction velocity<br />

CVLT Cali<strong>for</strong>nia Verbal Learning Test<br />

CVR-R<br />

coefficient <strong>of</strong> variation <strong>of</strong> the R-R interval<br />

CYP cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)<br />

CYP3a11 cytochrome P450 3a11<br />

D D-statistic<br />

DA dopamine; dopaminergic<br />

dbcAMP dibutyryl cyclic adenosine-3',5'-monophosphate<br />

DCV distribution <strong>of</strong> conduction velocities<br />

DEAE diethylaminoethyl (chromatography)<br />

DET diffusive equilibrium thin films<br />

DEYO death <strong>of</strong> young<br />

DFS decayed or filled surfaces, permanent teeth<br />

dfs covariate-adjusted number <strong>of</strong> caries<br />

DG dentate gyrus<br />

DGT diffusive gradient thin films<br />

DL DL-statistic<br />

DMEM Dulbecco’s Minimal Essential Medium<br />

DMEM/F12 Dulbecco’s Minimal Essential Medium/Ham’s F12<br />

DMFS decayed, missing, or filled surfaces, permanent teeth<br />

DMPS 2,3-dimercaptopropane 1-sulfonate<br />

DMSA 2,3-dimercaptosuccinic acid<br />

DMT Donnan membrane technique<br />

DMTU dimethylthiourea<br />

DNA deoxyribonucleic acid<br />

DO distraction osteogenesis<br />

DOC dissolved organic carbon<br />

DOM dissolved organic carbon<br />

DOPAc 3,4-dihydroxyphenylacetic acid<br />

DPASV differential pulse anodic stripping voltammetry<br />

dp/dt rate <strong>of</strong> left ventricular isovolumetric pressure<br />

<strong>II</strong>-xxv


DPPD N-N-diphenyl-p-phynylene-diamine<br />

DR drinking water<br />

DSA delayed spatial alternation<br />

DTC diethyl dithiocarbomate complex<br />

DTH delayed type hypersensitivity<br />

DTPA diethylenetriaminepentaacetic acid<br />

DTT dithiothreitol<br />

dw dry weight<br />

E embryonic day<br />

E2<br />

estradiol<br />

EBE early biological effect<br />

EBV Epstein-Barr virus<br />

EC European Community<br />

EC50<br />

effect concentration <strong>for</strong> 50% <strong>of</strong> test population<br />

eCB endocannabinoid<br />

ECG electrocardiogram<br />

Eco-SSL ecological soil screening level<br />

EDS energy dispersive spectrometers<br />

EDTA ethylenediaminetetraacetic acid<br />

EEDQ N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone<br />

EEG electroencephalogram<br />

EG egg<br />

EGF epidermal growth factor<br />

EGG effects on eggs<br />

EGPN egg production<br />

EKG electrocardiogram<br />

electro electrophysiological stimulation<br />

EM/CM experimental medium-to-control medium (ratio)<br />

EMEM Eagle’s Minimal Essential Medium<br />

eNOS endothelial nitric oxide synthase<br />

EP erythrocyte protoporphyrin<br />

<strong>EPA</strong> U.S. Environmental Protection Agency<br />

Epi epinephrine<br />

EPMA electron probe microanalysis<br />

EPO erythropoietin<br />

<strong>II</strong>-xxvi


EPSC excitatory postsynaptic currents<br />

EPT macroinvertebrates from the Ephemeroptera (mayflies),<br />

Plecoptera (stoneflies), and Trichoptera (caddisflies) group<br />

ERG electroretinogram; electroretinographic<br />

ERL effects range – low<br />

ERM effects range – median<br />

EROD ethoxyresorufin-O-deethylase<br />

ESCA electron spectroscopy <strong>for</strong> chemical analysis<br />

ESRD end-stage renal disease<br />

EST estradiol<br />

ESTH eggshell thinning<br />

ET endothelein; essential tremor<br />

ETOH ethyl alcohol<br />

EXAFS extended X-ray absorption fine structure<br />

EXANES extended X-ray absorption near edge spectroscopy<br />

F F-statistic<br />

F344 Fischer 344 (rat)<br />

FAV final acute value<br />

FBS fetal bovine serum<br />

FCS fetal calf serum<br />

FCV final chronic value<br />

FD food<br />

FEF <strong>for</strong>ced expiratory flow<br />

FEP free erythrocyte protoporphyrin<br />

FERT fertility<br />

FEV1<br />

<strong>for</strong>ced expiratory volume in one second<br />

FGF fibroblast growth factor (e.g., βFGF, αFGF)<br />

FI fixed interval (operant conditioning)<br />

FIAM free ion activity model<br />

FMLP N-<strong>for</strong>myl-L-methionyl-L-leucyl-L-phenylalanine<br />

fMRI functional magnetic resonance imaging<br />

FR fixed-ratio operant conditioning<br />

FSH follicle stimulating hormone<br />

FT3 free triiodothyronine<br />

FT4 free thyroxine<br />

<strong>II</strong>-xxvii


FTES free testosterone<br />

FT<strong>II</strong> Fagan Test <strong>of</strong> Infant Intelligence<br />

FTPLM flow-through permeation liquid membranes<br />

FURA-2 1-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benz<strong>of</strong>uranyloxy]-2-(2amino-5-methylphenoxy)<br />

ethane-N,N,N',N'-tetraacetic acid<br />

FVC <strong>for</strong>ced vital capacity<br />

(-GT (-glutamyl transferase<br />

G gestational day<br />

GABA gamma aminobutyric acid<br />

GAG glycosaminoglycan<br />

G12 CHV79 cells derived from the V79 cell line<br />

GCI General Cognitive Index<br />

GD gestational day<br />

GDP guanosine diphosphate<br />

GEE generalized estimating equations<br />

GFAAS graphite furnace atomic absorption spectroscopy<br />

GFR glomerular filtration rate<br />

GGT (-glutamyl transferase<br />

GH growth hormone<br />

GI gastrointestinal<br />

GIME-VIP gel integrated microelectrodes combined with voltammetric<br />

in situ pr<strong>of</strong>iling<br />

GIS geographic in<strong>for</strong>mation system<br />

GLU glutamate<br />

GMAV genus mean acute value<br />

GMCV genus mean chronic value<br />

GMP guanosine monophosphate<br />

GMPH general morphology<br />

GnRH gonadotropin releasing hormone<br />

GOT aspartate aminotransferase<br />

GP gross productivity<br />

G6PD, G6PDH glucose-6-phosphate dehydrogenase<br />

GPEI glutathione S-transferase P enhancer element<br />

gp91 phox NAD(P)H oxidase<br />

GPT glutamic-pyruvic transaminase<br />

GPx glutathione peroxidase<br />

<strong>II</strong>-xxviii


GRO growth<br />

GRP78 glucose-regulated protein 78<br />

GSD geometric standard deviation<br />

GSH reduced glutathione<br />

GSIM gill surface interaction model<br />

GSSG glutathione disulfide<br />

GST glutathione-S-transferase<br />

GSTP placental glutathione transferase<br />

GTP guanosine triphosphate<br />

GV gavage<br />

H + acidity<br />

3<br />

H hydrogen-3 radionuclide (tritium)<br />

HA humic acid; hydroxyapatite<br />

Hb hemoglobin<br />

HBEF Hubbard Brook Experimenatl Forest<br />

HBSS Hank’s Balanced Salt Solution<br />

HCG; hCG human chorionic gonadotropin<br />

Hct hematocrit<br />

HDL high-density lipoprotein (cholesterol)<br />

HEP habitat evaluation procedure<br />

HET Binghamton heterogeneous stock<br />

HFPLM hollow fiber permeation liquid membranes<br />

Hgb hemoglobin<br />

HGF hepatocyte growth factor<br />

HH hydroxylamine hydrochloride<br />

H-H high-high<br />

HHANES Hispanic Health and Nutrition Examination Survey<br />

H-L high-low<br />

HLA human leukocyte antigen<br />

H-MEM minimum essential medium/nutrient mixture–F12-Ham<br />

HMP hexose monophosphate shunt pathway<br />

HNO3<br />

nitric acid<br />

H2O2<br />

hydrogen peroxide<br />

HOME Home Observation <strong>for</strong> Measurement <strong>of</strong> Environment<br />

HOS TE human osteosarcoma cells<br />

<strong>II</strong>-xxix


HPLC high-pressure liquid chromatography<br />

H3PO4<br />

phosphoric acid<br />

HPRT hypoxanthine phosphoribosyltransferase (gene)<br />

HR heart rate<br />

HSI habitat suitability indices<br />

H2SO4<br />

sulfuric acid<br />

HSPG heparan sulfate proteoglycan<br />

Ht hematocrit<br />

HTC hepatoma cells<br />

hTERT catalytic subunit <strong>of</strong> human telomerase<br />

HTN hypertension<br />

IBL integrated blood lead index<br />

IBL Η WRAT-R integrated blood lead index Η Wide Range Achievement<br />

Test-Revised (interaction)<br />

ICD International Classification <strong>of</strong> Diseases<br />

ICP inductively coupled plasma<br />

ICP-AES inductively coupled plasma atomic emission spectroscopy<br />

ICP-MS, ICPMS inductively coupled plasma mass spectrometry<br />

ID-MS isotope dilution mass spectrometry<br />

IFN interferon (e.g., IFN-()<br />

Ig immunoglobulin (e.g., IgA, IgE, IgG, IgM)<br />

IGF-1 insulin-like growth factor 1<br />

IL interleukin (e.g., IL-1, IL-1∃, IL-4, IL-6, IL-12)<br />

ILL incipient lethal level<br />

immuno immunohistochemical staining<br />

IMP inosine monophosphate<br />

iNOS inducible nitric oxide synthase<br />

i.p., IP intraperitoneal<br />

IPSC inhibitory postsynaptic currents<br />

IQ intelligence quotient<br />

IRT interresponse time<br />

ISEL in situ end labeling<br />

ISI interstimulus interval<br />

i.v., IV intravenous<br />

IVCD intraventricular conduction deficit<br />

<strong>II</strong>-xxx


JV juvenile<br />

KABC Kaufman Assessment Battery <strong>for</strong> Children<br />

KTEA Kaufman Test <strong>of</strong> Educational Achievement<br />

KXRF, K-XRF K-shell X-ray fluorescence<br />

LA lipoic acid<br />

LB laying bird<br />

LC lactation<br />

LC50<br />

lethal concentration at which 50% <strong>of</strong> exposed animals die<br />

LC74<br />

lethal concentration at which 74% <strong>of</strong> exposed animals die<br />

LD50<br />

lethal dose at which 50% <strong>of</strong> exposed animals die<br />

LDH lactate dehydrogenase<br />

LDL low-density lipoprotein (cholesterol)<br />

L-dopa 3,4-dihydroxyphenylalanine (precursor <strong>of</strong> dopamine)<br />

LE Long Evans (rat)<br />

LET linear energy transfer (radiation)<br />

LH luteinizing hormone<br />

LHRH luteinizing hormone releasing hormone<br />

LN lead nitrate<br />

L-NAME L-N G -nitroarginine methyl ester<br />

LOAEL lowest-observed adverse effect level<br />

LOEC lowest-observed-effect concentration<br />

LOWESS locally weighted scatter plot smoother<br />

LPO lipoperoxide<br />

LPP lipid peroxidation potential<br />

LPS lipopolysaccharide<br />

LT leukotriene<br />

LT50<br />

time to kill 50%<br />

LTER Long-Term Ecological Research (sites)<br />

LTP long term potentiation<br />

LVH left ventricular hypertrophy<br />

µPIXE micr<strong>of</strong>ocused particle induced X-ray emission<br />

µSXRF micr<strong>of</strong>ocused synchrotron-based X-ray fluorescence<br />

MA mature<br />

MA-10 mouse Leydig tumor cell line<br />

MANCOVA multivariate analysis <strong>of</strong> covariance<br />

<strong>II</strong>-xxxi


MAO monoamine oxidase<br />

MATC maximum acceptable threshold concentration<br />

MDA malondialdehyde<br />

MDA-TBA malondialdehyde-thiobarbituric acid<br />

MDCK kidney epithelial cell line<br />

MDI Mental Development Index (score)<br />

MDRD Modification <strong>of</strong> Diet in Renal Disease (study)<br />

MEM Minimal Essential Medium<br />

MG microglobulin<br />

Mg-ATPase magnesium-dependent adenosine triphosphatase<br />

MiADMSA monoisamyl dimercaptosuccinic acid<br />

Mi-DMSA mi monoisoamyl dimercaptosuccinic acid<br />

MK-801 NMDA receptor antagonist<br />

MLR mixed lymphocyte response<br />

MMSE Mini-Mental State Examination<br />

MMTV murine mammary tumor virus<br />

MN micronuclei <strong>for</strong>mation<br />

MND motor neuron disease<br />

MNNG N-methyl-N'-nitro-N-nitrosoguanidine<br />

MPH morphology<br />

MRI magnetic resonance imaging<br />

mRNA messenger ribonucleic acid<br />

MROD methoxyresorufin-O-demethylase<br />

MRS magnetic resonance spectroscopy<br />

MS mass spectrometry<br />

MSCA McCarthy Scales <strong>of</strong> Children’s Abiltities<br />

mSQGQs mean sediment quality guideline quotients<br />

MT metallothionein<br />

MVV maximum voluntary ventilation<br />

MW molecular weight (e.g., high-MW, low-MW)<br />

N, n number <strong>of</strong> observations<br />

N/A not available<br />

NAAQS National Ambient <strong>Air</strong> <strong>Quality</strong> Standards<br />

NAC N-acetyl cysteine<br />

NAD nicotinamide adenine dinucleotide<br />

<strong>II</strong>-xxxii


NADH reduced nicotinamide adenine dinucleotide<br />

NADP nicotinamide adenine dinucleotide phosphate<br />

NAD(P)H, NADPH reduced nicotinamide adenine dinucleotide phosphate<br />

NADS nicotinamide adenine dinucleotide synthase<br />

NAF nafenopin<br />

NAG N-acetyl-∃-D-glucosaminidase<br />

Na-K-ATPase sodium-potassium-dependent adenosine triphosphatase<br />

NAWQA National Water-<strong>Quality</strong> Assessment<br />

NBT nitro blue tetrazolium<br />

NCBP National Contaminant Biomonitoring Program<br />

NCD nuclear chromatin decondensation (rate)<br />

NCS newborn calf serum<br />

NCTB Neurobehavioral Core Test Battery<br />

NCV nerve conduction velocity<br />

ND non-detectable; not detected<br />

NDI nuclear divison index<br />

NE norepinephrine<br />

NES Neurobehavioral Evaluation System<br />

NF-κB nuclear transcription factor-κB<br />

NGF nerve growth factor<br />

NHANES National Health and Nutrition Examination Survey<br />

NIOSH National Institute <strong>for</strong> Occupational Safety and Health<br />

NIST National Institute <strong>for</strong> Standards and Technology<br />

NK natural killer<br />

NMDA N-methyl-D-aspartate<br />

NMDAR N-methyl-D-aspartate receptor<br />

NMR nuclear magnetic resonance<br />

NO nitric oxide<br />

NO2<br />

nitrogen dioxide<br />

NO3<br />

nitrate<br />

NOAEC no-observed-adverse-effect concentration<br />

NOAEL no-observed-adverse-effect level<br />

NOEC no-observed-effect concentration<br />

NOEL no-observed-effect level<br />

NOM natural organic matter<br />

<strong>II</strong>-xxxiii


NORs nucleolar organizing regions<br />

NOS nitric oxide synthase; not otherwise specified<br />

NOx<br />

nitrogen oxides<br />

NP net productivity<br />

NPSH nonprotein sulfhydryl<br />

NR not reported<br />

NRC National Research Council<br />

NRK normal rat kidney<br />

NS nonsignificant<br />

NSAID non-steroidal anti-inflammatory agent<br />

NT neurotrophin<br />

NTA nitrilotriacetic acid<br />

O2<br />

oxygen<br />

ODVP <strong>of</strong>fspring development<br />

OH hydroxyl<br />

7-OH-coumarin 7-hydroxy-coumarin<br />

1,25-OH-D, 1,25-OH D3 1,25-dihydroxyvitamin D<br />

24,25-OH-D3<br />

24,25-dihydroxyvitamin D<br />

25-OH-D3<br />

25-hydroxyvitamin D<br />

8-OHdG 8-hydroxy-2'-deoxyguanosine<br />

O horizon <strong>for</strong>est floor<br />

OR odds ratio; other oral<br />

OSWER Office <strong>of</strong> Solid Waste and Emergency Response<br />

P, p probability value<br />

P300 event-related potential<br />

P450 1A1 cytochrome P450 1A1<br />

P450 1A2 cytochrome P450 1A2<br />

P450 CYP3a11 cytochrome P450 3a11<br />

PAD peripheral arterial disease<br />

PAH polycyclic aromatic hydrocarbon<br />

PAI-1 plasminogen activator inhibitor-1<br />

PAR population attributable risk<br />

Pb lead<br />

203<br />

Pb lead-203 radionuclide<br />

204 206 207 208<br />

Pb, Pb, Pb, Pb stable isotopes <strong>of</strong> lead-204, -206, -207, -208, respectively<br />

<strong>II</strong>-xxxiv


210 Pb lead-210 radionuclide<br />

Pb(Ac)2<br />

lead acetate<br />

PbB blood lead concentration<br />

PbCl2<br />

lead chloride<br />

Pb(ClO4)2<br />

lead chlorate<br />

PBG-S porphobilinogen synthase<br />

PBMC peripheral blood mononuclear cells<br />

Pb(NO3)2<br />

lead nitrate<br />

PbO lead oxides (or litharge)<br />

PBP progressive bulbar paresis<br />

PbS galena<br />

PbU urinary lead<br />

PC12 pheochromocytoma cell<br />

PCR polymerase chain reaction<br />

PCV packed cell volume<br />

PDE phosphodiesterase<br />

PDGF platelet-derived growth factor<br />

PDI Psychomotor Development Index<br />

PEC probable effect concentration<br />

PEF expiratory peak flow<br />

PG prostaglandin (e.g., PGE2, PGF2); prostate gland<br />

PHA phytohemagglutinin A<br />

Pi inorganic phosphate<br />

PIXE particle induced X-ray emission<br />

PKC protein kinase C<br />

pl NEpi plasma norepinephrine<br />

PMA progressive muscular atrophy<br />

PMN polymorphonuclear leucocyte<br />

PMR proportionate mortality ratio<br />

PN postnatal (day)<br />

P5N pyrimidine 5'-nucleotidase<br />

PND postnatal day<br />

p.o., PO per os (oral administration)<br />

POMS Pr<strong>of</strong>ile <strong>of</strong> Mood States<br />

ppb parts per billion<br />

<strong>II</strong>-xxxv


ppm parts per million<br />

PPVT-R Peabody Picture Vocabulary Test-Revised<br />

PRA plasma renin activity<br />

PRL prolactin<br />

PROG progeny counts or numbers<br />

PRR prevalence rate ratio<br />

PRWT progeny weight<br />

PST percent transferrin saturation<br />

PTH parathyroid hormone<br />

PTHrP parathyroid hormone-related protein<br />

PVC polyvinyl chloride<br />

PWM pokeweed mitogen<br />

PRWT progeny weight<br />

QA/QC quality assurance/quality control<br />

Q/V flux <strong>of</strong> air (Q) divided by volume <strong>of</strong> culture (V)<br />

r Pearson correlation coefficient<br />

R 2 multiple correlation coefficient<br />

r 2 correlation coefficient<br />

226<br />

Ra most stable isotope <strong>of</strong> radium<br />

R/ALAD ratio <strong>of</strong> ALAD activity be<strong>for</strong>e and after reactivation<br />

RAVLT Rey Auditory Verbal Learning Test<br />

86<br />

Rb rubidium-86 radionuclide<br />

RBA relative bioavailablity<br />

RBC red blood cell; erythrocyte<br />

RBF renal blood flow<br />

RBP retinol binding protein<br />

RBPH reproductive behavior<br />

RCPM Ravens Colored Progressive Matrices<br />

REL rat epithelial (cells)<br />

REP<br />

reproduction<br />

RHIS reproductive organ histology<br />

222<br />

Rn most stable isotope <strong>of</strong> radon<br />

RNA ribonucleic acid<br />

ROS reactive oxygen species<br />

ROS 17.2.8 rat osteosarcoma cell line<br />

<strong>II</strong>-xxxvi


RPMI 1640 Roswell Park Memorial Institute basic cell culture medium<br />

RR relative risk; rate ratio<br />

RT reaction time<br />

RSEM resorbed embryos<br />

RSUC reproductive success (general)<br />

RT reproductive tissue<br />

∑SEM sum <strong>of</strong> the molar concentrations <strong>of</strong> simultaneously extracted metal<br />

SA7 simian adenovirus<br />

SAB Science Advisory Board<br />

SAM S-adenosyl-L-methionine<br />

SBIS-4 Stan<strong>for</strong>d-Binet Intelligence Scale-4th edition<br />

s.c., SC subcutaneous<br />

SCAN Test <strong>for</strong> Auditory Processing Disorders<br />

SCE selective chemical extraction; sister chromatid exchange<br />

SCP stripping chronopotentiometry<br />

SD Spraque-Dawley (rat); standard deviation<br />

SDH succinic acid dehydrogenase<br />

SDS sodium dodecyl sulfate; Symbol Digit Substitution<br />

SE standard error; standard estimation<br />

SEM standard error <strong>of</strong> the mean<br />

SES socioeconomic status<br />

sGC soluble guanylate cyclase<br />

SH sulfhydryl<br />

SHBG sex hormone binding globulin<br />

SHE Syrian hamster embryo cell line<br />

SIMS secondary ion mass spectrometry<br />

SIR standardized incidence ratio<br />

SLP synthetic leaching procedure<br />

SM sexually mature<br />

SMAV species mean acute value<br />

SMR standardized mortality ratio<br />

SNAP Schneider Neonatal Assessment <strong>for</strong> Primates<br />

SNP sodium nitroprusside<br />

SO2<br />

sulfur dioxide<br />

SOD superoxide dismutase<br />

<strong>II</strong>-xxxvii


SOPR sperm-oocyte penetration rate<br />

SPCL sperm cell counts<br />

SPCV sperm cell viability<br />

SQGs sediment quality guidelines<br />

SRA Self Reported Antisocial Behavior scale<br />

SRD Self Report <strong>of</strong> Delinquent Behavior<br />

SRIF somatostatin<br />

SRM Standard Reference Material<br />

SRT simple reaction time<br />

SSADMF Social Security Administration Death Master File<br />

SSB single-strand breaks<br />

SSEP somatosensory-evoked potential<br />

StAR steroidogenic acute regulatory protein<br />

STORET STOrage and RETrieval<br />

SVC sensory conduction velocity<br />

SVRT simple visual reaction time<br />

T testosterone<br />

TA tail<br />

TABL time-averaged blood lead<br />

T&E threatened and endangered (species)<br />

TAT tyrosine aminotransferase<br />

TB tibia<br />

TBARS thiobarbituric acid-reactive species<br />

TBPS Total Behavior Problem Score<br />

TCDD methionine-choline-deficient diet<br />

T cell T lymphocyte<br />

TCLP toxic characteristic leaching procedure<br />

TE testes<br />

TEC threshold effect concentration<br />

TEDG testes degeneration<br />

TEL tetraethyl lead<br />

TES testosterone<br />

TEWT testes weight<br />

TF transferrin, translocation factor<br />

TG 6-thioguanine<br />

<strong>II</strong>-xxxviii


TGF trans<strong>for</strong>ming growth factor<br />

TH tyrosine hydroxylase<br />

232 Th stable isotope <strong>of</strong> thorium-232<br />

TLC Treatment <strong>of</strong> <strong>Lead</strong>-exposed Children (study)<br />

TNF tumor necrosis factor (e.g., TNF-α)<br />

TOF time-<strong>of</strong>-flight<br />

tPA plasminogen activator<br />

TPRD total production<br />

TRH thyroid releasing hormone<br />

TRV toxicity reference value<br />

TSH thyroid stimulating hormone<br />

TSP triple-super phosphate<br />

TT3 total triiodothyronine<br />

TT4 serum total thyroxine<br />

TTES total testosterone<br />

TTR transthyretin<br />

TU toxic unit<br />

TWA time-weighted average<br />

TX tromboxane (e.g., TXB2)<br />

U uriniary<br />

235 238<br />

U, U uranium-234 and -238 radionuclides<br />

UCP urinary coproporphyrin<br />

UDP uridine diphosphate<br />

UNECE United Nations Economic Commission <strong>for</strong> Europe<br />

Ur urinary<br />

<strong>US</strong>FWS U.S. Fish and Wildlife Service<br />

<strong>US</strong>GS United States Geological Survey<br />

UV ultraviolet<br />

V79 Chinese hamster lung cell line<br />

VA Veterans Administration<br />

VC vital capacity; vitamin C<br />

VDR vitamin D receptor<br />

VE vitamin E<br />

VEP visual-evoked potential<br />

VI variable-interval<br />

<strong>II</strong>-xxxix


vit C vitamin C<br />

vit E vitamin E<br />

VMA vanilmandelic acid<br />

VMI Visual-Motor Integration<br />

VSM vascular smooth muscle (cells)<br />

VSMC vascular smooth muscle cells<br />

WAIS Wechsler Adult Intelligence Scale<br />

WDS wavelength dispersive spectrometers<br />

WHO World Health Organization<br />

WISC Wechsler Intelligence Scale <strong>for</strong> Children<br />

WISC-R Wechsler Intelligence Scale <strong>for</strong> Children-Revised<br />

WO whole organism<br />

WRAT-R Wide Range Achievement Test-Revised<br />

WT wild type<br />

WTHBF-6 human liver cell line<br />

ww wet weight<br />

XAFS X-ray absorption fine structure<br />

XANES X-ray absorption near edge spectroscopy<br />

XAS X-ray absorption spectroscopy<br />

XPS X-ray photoelectron spectroscopy<br />

X-rays synchrotron radiation<br />

XRD X-ray diffraction<br />

XRF X-ray fluorescence<br />

ZAF correction in reference to three components <strong>of</strong> matrix effects:<br />

atomic number (Z), absorption (A), and fluorescence (F)<br />

ZnNa2 DTPA zinc disodium diethylenetriaminepentaacetic acid<br />

ZnNa2 EDTA zinc disodium ethylenediaminetetraacetic acid<br />

ZPP zinc protoporphyrin<br />

<strong>II</strong>-xl


AX6. CHAPTER 6 ANNEX<br />

AX6-1


ANNEX TABLES AX6-2<br />

AX6-2


AX6-3<br />

Table AX6-2.1. Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Bellinger et al. (1992)<br />

U.S.<br />

Dietrich et al.<br />

(1991, 1992, 1993a);<br />

Ris et al. (2004)<br />

U.S.<br />

Canfield et al. (2003a)<br />

U.S.<br />

148 subjects from the Boston Prospective Study<br />

were re-evaluated at 10 yrs <strong>of</strong> age. The WISCR<br />

was used to index intellectual status. Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

253-260 children followed since birth in the<br />

Cincinnati Pb Study were re-evaluated at 4, 5, and<br />

6.5 yrs <strong>of</strong> age. At 4 and 5 yrs, the KABC was used<br />

to index intellectual status. At 6.5 yrs, the WISCR<br />

was administered. At 15-17 yrs <strong>of</strong> age, 195<br />

Cincinnati Pb Study subjects were re-evaluated by<br />

use <strong>of</strong> a comprehensive neuropsychological battery<br />

that yielded a “Learning/IQ” factor in a principal<br />

components analysis. Extensive assessment <strong>of</strong><br />

medical and sociodemographic covariates.<br />

172 predominantly African-American, lower<br />

socioeconomic status children in Rochester, NY<br />

followed since they were 5 to 7 mos were evaluated<br />

at 3 and 5 yrs. An abbreviated <strong>for</strong>m <strong>of</strong> the<br />

Stan<strong>for</strong>d-Binet Intelligence Scale-4 (SBIS-4) was<br />

used to index intellectual status. Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

Cord and serial postnatal<br />

blood Pb assessments<br />

Cord blood Pb grouping 10 µg/dL<br />

Blood Pb at 2 yrs 6.5<br />

(SD 4.9) µg/dL<br />

Prenatal (maternal) and serial<br />

postnatal blood Pb<br />

assessments<br />

Prenatal blood Pb 8.3<br />

(SD 3.7) µg/dL<br />

Blood Pb at 2 yrs 17.4<br />

(SD 8.8) µg/dL<br />

Serial postnatal blood Pb<br />

Blood Pb at 2 yrs<br />

9.7 µg/dL<br />

Increase <strong>of</strong> 10 µg/dL in blood Pb level at age two was<br />

associated with a decrement <strong>of</strong> ~6 IQ points. Relationship<br />

was stronger <strong>for</strong> verbal compared to per<strong>for</strong>mance IQ.<br />

Prenatal exposure to Pb as indexed by cord blood Pb levels<br />

was unrelated to psychometric intelligence.<br />

Few statistically significant relationships between blood Pb<br />

indices and covariate-adjusted KABC scales at 4 and 5 yrs<br />

<strong>of</strong> age. One KABC subscale that assesses visual-spatial<br />

skills was associated with late postnatal blood Pb levels<br />

following covariate adjustment. After covariate<br />

adjustment, avg postnatal blood Pb level was significantly<br />

associated with WISCR per<strong>for</strong>mance IQ at 6.5 yrs. Blood<br />

Pb concentrations >20 µg/dL were associated with deficits<br />

in per<strong>for</strong>mance IQ on the order <strong>of</strong> 7 points compared with<br />

children with mean blood Pb concentrations


AX6-4<br />

Table AX6-2.1 (cont’d). Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Bellinger and<br />

Needleman (2003)<br />

U.S.<br />

Chen et al. (2005)<br />

U.S.<br />

Reanalysis <strong>of</strong> data from the Boston Prospective<br />

Study focusing on 48 subjects at 10 yrs <strong>of</strong> age<br />

whose blood Pb levels never exceeded 10 µg/dL.<br />

WISCR was used to index intellectual status. See<br />

also Bellinger et al. (1992)<br />

Repeat measure psychometric data on 780 children<br />

enrolled in Treatment <strong>of</strong> Pb-Exposed Children<br />

(TLC) clinical trial were analyzed to determine if<br />

blood Pb concentrations at 2 yrs <strong>of</strong> age constitute a<br />

critical period <strong>of</strong> exposure <strong>for</strong> expression <strong>of</strong> later<br />

neurodevelopmental deficits. Data <strong>for</strong> placebo and<br />

active drug groups were combined in these<br />

analyses, which spanned ~2 to 7 yrs <strong>of</strong> age.<br />

Measures <strong>of</strong> intellectual status included the Bayley<br />

Mental Development Index (MDI) and full scale IQ<br />

derived from age-appropriate Wechsler scales.<br />

Serial postnatal blood Pb<br />

Blood Pb at 2 yrs 6.5<br />

(SD 4.9) µg/dL<br />

Blood Pb<br />

Range 20-44 µg/dL<br />

Baseline blood Pb 26<br />

(SD 26.5) µg/dL in both drug<br />

and placebo groups<br />

Blood Pb at 7 yrs 8.0<br />

(SD 4.0) µg/dL<br />

IQ was inversely related to two-yr blood Pb levels<br />

following covariate adjustment. Blood Pb coefficient<br />

(!1.56) was greater than that derived from analyses<br />

including children with concentrations above 10 µg/dL<br />

(!0.58). Authors conclude that children’s IQ scores are<br />

reduced at Pb levels still prevalent in U.S.<br />

Association between blood Pb and psychometric<br />

intelligence increased in strength as children became older,<br />

whereas the relation between baseline (2 yr) blood Pb and<br />

IQ attenuated. Peak blood Pb concentration thus does not<br />

fully account <strong>for</strong> the observed association in older children<br />

between their lower blood Pb concentrations and IQ. The<br />

effect <strong>of</strong> concurrent blood Pb on IQ may thusly be greater<br />

than currently believed. Authors conclude that these data<br />

(a) support the idea that Pb exposure continues to be toxic<br />

to children as they reach school age and (b) do not lend<br />

support to the interpretation that majority <strong>of</strong> the damage is<br />

done by the time the child reaches 2 to 3 yrs <strong>of</strong> age.


AX6-5<br />

Table AX6-2.1 (cont’d). Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Wasserman et al. (1992,<br />

1994, 2003); Factor-<br />

Litvak et al. (1999)<br />

Yugoslavia<br />

Birth cohort <strong>of</strong> ~300-400 infants followed since<br />

birth residing in two towns in Kosovo, Yugoslavia,<br />

one group near a longstanding Pb smelter and<br />

battery manufacturing facility and another in a<br />

relatively unexposed location 25 miles away.<br />

Intellectual status was monitored from 2 to<br />

10-12 yrs <strong>of</strong> age with the Bayley Scales <strong>of</strong> Infant<br />

Development, McCarthy Scales <strong>of</strong> Children’s<br />

Abilities, and WISC<strong>II</strong>I. Extensive assessment <strong>of</strong><br />

medical and sociodemographic covariates.<br />

Maternal prenatal, umbilical<br />

cord, and serial postnatal<br />

blood Pb<br />

Maternal blood Pb in exposed<br />

area 19.9 (SD 7.7) µg/dL,<br />

unexposed area 5.6 (SD 2.0)<br />

µg/dL<br />

Umbilical cord blood Pb in<br />

exposed area 22.2 (SD 8.1)<br />

µg/dL, unexposed area 5.5<br />

(SD 3.3) µg/dL<br />

Blood Pb at 2 yrs in<br />

exposed area 35.4 µg/dL,<br />

unexposed area 8.5 µg/dL<br />

Postnatal blood Pb increment from 10 to 30 µg/dL at 2 yrs<br />

<strong>of</strong> age associated with covariate-adjusted decline <strong>of</strong> 2.5<br />

points in Bayley MDI. Maternal and cord blood Pb not<br />

consistently associated with Bayley outcomes. Higher<br />

prenatal and cord blood Pb concentrations associated with<br />

lower McCarthy General Cognitive Index (GCI) scores at<br />

4 yrs. Scores on the Perceptual-Per<strong>for</strong>mance subscale<br />

particularly affected. After covariate-adjustment, children<br />

<strong>of</strong> mothers with prenatal blood Pb levels >20 µg/dL scored<br />

a full standard deviation below children in the lowest<br />

exposure group (


AX6-6<br />

Table AX6-2.1 (cont’d). Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Schnaas et al. (2000)<br />

Mexico<br />

Schnaas et al. (2006)<br />

Mexico<br />

Gomaa et al. (2002)<br />

Mexico<br />

112 children followed since birth with complete<br />

psychometric data from the Mexico City<br />

Prospective Study were examined. Intellectual<br />

status indexed by General Cognitive Index (GCI)<br />

from McCarthy Scales <strong>of</strong> Children’s Abilities<br />

(MSCA). Purpose <strong>of</strong> the study was to determine if<br />

magnitude <strong>of</strong> the effect <strong>of</strong> postnatal blood Pb levels<br />

on cognition varies with time between blood Pb<br />

and cognitive assessments.<br />

From the Mexico City Prospective Study, 150<br />

children followed since birth with complete data<br />

<strong>for</strong> all covariates were examined. Intelligence from<br />

age 6 to 10 yrs was assessed using the WISC-R.<br />

Blood Pb measurements from various time points,<br />

starting from maternal blood Pb levels during the<br />

2nd trimester to postnatal Pb levels at age 10 yrs.<br />

197 two yr-old children residing in Mexico City<br />

followed since birth. Bayley Scales <strong>of</strong> Infant<br />

Development Mental Development Index (MDI)<br />

used to index intellectual status. Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

Serial postnatal blood Pb<br />

Avg blood Pb<br />

24-36 mos 9.7<br />

(range 3-48) µg/dL<br />

Serial prenatal (maternal) and<br />

postnatal blood Pb<br />

Geometric mean blood Pb<br />

During pregnancy 8.0<br />

(range 1-33) µg/dL<br />

Age 1-5 yrs 9.8<br />

(range 2.8-36.4) µg/dL<br />

Age 6-10 yrs 6.2<br />

(range 2.2-18.6) µg/dL<br />

Umbilical cord and serial<br />

postnatal blood Pb<br />

Umbilical cord blood<br />

Pb 6.7 (SD 3.4) µg/dL<br />

Blood Pb at 2 yrs 8.4<br />

(SD 4.6) µg/dL<br />

Maternal tibial and patellar<br />

bone Pb<br />

Patellar (trabecular)<br />

bone Pb 17.9 (SD 15.2) µg/g<br />

A number <strong>of</strong> significant interactions observed between<br />

blood Pb levels and age <strong>of</strong> assessment. Greatest effect<br />

observed at 48 mos, when a 5.8 deficit in adjusted GCI<br />

scores was observed <strong>for</strong> each natural log increment in<br />

blood Pb. Authors concluded that four to five yrs <strong>of</strong> age<br />

appears to be a critical period <strong>for</strong> manifestation <strong>of</strong> earlier<br />

postnatal blood Pb level effects on cognition.<br />

Among all the Pb variables at the various time points, only<br />

log-trans<strong>for</strong>med blood Pb levels during the 3rd trimester<br />

were significantly associated with full scale IQ at ages 6 to<br />

10 yrs, after adjusting <strong>for</strong> potential confounders. A 3.44<br />

point deficit in full scale IQ was observed <strong>for</strong> each natural<br />

log increment in blood Pb.<br />

The authors note that, given the modest sample size and<br />

relatively low power <strong>of</strong> this study, they do not claim that<br />

Pb exposure from other developmental period has no effect<br />

on child IQ.<br />

Umbilical cord blood Pb and patellar (trabecular) bone Pb<br />

significantly associated with lower Bayley MDI scores.<br />

Maternal trabecular bone Pb levels predicted poorer<br />

sensorimotor functioning at two yrs independent <strong>of</strong><br />

concentration Pb measured in cord blood. Increase in cord<br />

blood Pb level from 5 to 10 µg/dL was associated with a<br />

3.1 point decrement in adjusted MDI scores. In relation to<br />

lowest quartile <strong>of</strong> trabecular bone Pb, the 2nd, 3rd, and 4th<br />

quartiles were associated with 5.4, 7.2, and 6.5 decrement<br />

in MDI following covariate adjustment. Authors<br />

concluded that higher maternal trabecular bone Pb levels<br />

constitute an independent risk factor <strong>for</strong> impaired mental<br />

development in infancy, likely due to the mobilization <strong>of</strong><br />

maternal bone Pb stores over gestation.


AX6-7<br />

Table AX6-2.1 (cont’d). Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America (cont’d)<br />

Téllez-Rojo et al.<br />

(2006)<br />

Mexico<br />

Australia<br />

Baghurst et al. (1992);<br />

McMichael et al.<br />

(1994); Tong et al.<br />

(1996)<br />

Australia<br />

294 one and two yr-olds residing in Mexico City<br />

followed since birth. The Bayley Scales <strong>of</strong> Infant<br />

Development-<strong>II</strong> (MDI and PDI) were used to index<br />

developmental status. There was extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

400-500 subjects residing in and near Port Pirie,<br />

Australia and followed since birth were re-evaluated<br />

at 7 to 8 and 11-13 yrs <strong>of</strong> age. WISCR was used to<br />

index intellectual status at both ages. Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

Umbilical cord blood Pb and<br />

postnatal blood Pb at 12 and<br />

24 mos<br />

Umbilical cord blood Pb 4.8<br />

(SD 3.0) µg/dL<br />

Blood Pb at 1 yr 4.27 (SD<br />

2.1) µg/dL<br />

Blood Pb at 2 yrs 4.3 (SD<br />

2.2) µg/dL<br />

Maternal prenatal, umbilical<br />

cord and serial postnatal blood<br />

Pb<br />

Antenatal avg blood Pb<br />

10.1 (SD 3.9) µg/dL<br />

Umbilical cord blood Pb<br />

9.4 (SD 3.9) µg/dL<br />

Blood Pb at 2 yrs<br />

geometric mean 21.3<br />

(SD 1.2) µg/dL<br />

Deciduous central incisor<br />

whole tooth Pb<br />

Tooth Pb geometric 8.8<br />

(SD 1.9) µg/g<br />

Blood Pb at 12 mos was not associated with MDI at either<br />

age. Blood Pb at 24 mos was significantly associated with<br />

24 mo MDI. An increase <strong>of</strong> one logarithmic unit in 24 mo<br />

blood Pb level was associated with a reduction <strong>of</strong> ~5 points<br />

in MDI. Findings <strong>for</strong> PDI were similar. In comparison to<br />

a supplemental subsample <strong>of</strong> 90 subjects with blood Pb<br />

levels >10 µg/dL, the coefficient <strong>for</strong> blood Pb was<br />

significantly larger <strong>for</strong> infants never exceeding that level<br />

<strong>of</strong> internal dose. A steeper inverse slope was observed<br />

over the blood Pb range up to 5 µg/dL (!1.71 points per<br />

1 µg/dL increase in blood Pb, p = 0.01) compared to the<br />

range between 5 and 10 µg/dL (!0.94 points, p = 0.12);<br />

however, these slopes were not significantly different<br />

(p = 0.34). In conclusion, a major finding <strong>of</strong> this<br />

prospective study was that a significant inverse<br />

relationship between blood Pb concentration and<br />

neurodevelopment was observed among children whose<br />

blood Pb levels did not exceed 10 µg/dL at any age.<br />

Significant decrements in covariate-adjusted full scale IQ<br />

were observed in relationship to postnatal blood Pb levels<br />

at both ages. At 7 to 8 yrs <strong>of</strong> age a loss <strong>of</strong> 5.3 points was<br />

associated with an increase in blood Pb from 10 to<br />

30 µg/dL. At 11-13 yrs, mean full scale IQ declined by 3.0<br />

points <strong>for</strong> an increase in lifetime avg blood Pb<br />

concentrations from 10 to 20 µg/dL. Pb levels in central<br />

upper incisors were also associated with lower 7-8 yr IQ<br />

following covariate adjustment. Adjusted estimated<br />

decline in IQ across the range <strong>of</strong> tooth Pb from 3 to<br />

22 ppm was 5.1 points.


AX6-8<br />

Table AX6-2.1 (cont’d). Prospective Longitudinal Cohort Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Australia (cont’d)<br />

Cooney et al. (1991)<br />

Australia<br />

Asia<br />

Shen et al. (1998)<br />

China<br />

175 subjects from the Sydney, Australia Prospective<br />

Study were assessed at 7 yrs <strong>of</strong> age. The WISCR<br />

was used to index intellectual status. Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

characteristics.<br />

Pregnant women and newborns in Shanghai, China<br />

recruited from health care facilities in the community<br />

on the basis <strong>of</strong> cord blood Pb concentration<br />

percentiles (30th and 70th) yielding a total N <strong>of</strong> 173<br />

subjects. The Bayley Scales <strong>of</strong> Infant Development<br />

Mental Development Index (MDI) and Psychomotor<br />

Development Index (PDI) were used to index<br />

sensorimotor/intellectual status at 3, 6, and 12 mos.<br />

Extensive assessment <strong>of</strong> medical and<br />

sociodemographic characteristics.<br />

Maternal and cord blood Pb<br />

Cord blood Pb 8.4 µg/dL<br />

(SD not given)<br />

Blood Pb at 2 yr 15.8 µg/dL<br />

(SD not given)<br />

Cord blood Pb<br />

“High group” 13.4 (SD 2.0)<br />

µg/dL<br />

“Low group” 5.3 (SD 1.4)<br />

µg/dL<br />

Blood Pb at 1 yr<br />

“High group” 14.9 (SD 8.7)<br />

µg/dL<br />

“Low group” 14.4 (SD 7.7)<br />

µg/dL<br />

Blood indices <strong>of</strong> Pb exposure were not associated with any<br />

measure <strong>of</strong> psychometric intelligence. Authors conclude<br />

that the evidence from their study indicates that if<br />

developmental deficits do occur at blood Pb levels<br />


AX6-9<br />

Table AX6-2.2. Meta- and Pooled-Analyses <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Lanphear et al. (2005) Pooled analysis <strong>of</strong> seven international prospective<br />

studies involving 1,333 school-age children.<br />

Primary outcome measure was full-scale IQ as<br />

assessed by age-appropriate Wechsler scale.<br />

Measures <strong>of</strong> exposure were concurrent, peak, avg<br />

lifetime and “early” blood Pb (i.e. mean blood Pb<br />

from 6-24 mos). Cord blood Pb was also<br />

investigated <strong>for</strong> those studies that collected these<br />

samples at birth. Multivariate regression models<br />

were developed adjusting <strong>for</strong> site as well as 10<br />

common covariates. Blood Pb measure with the<br />

largest adjusted R 2 was nominated a priori as the<br />

preferred index <strong>for</strong> relating Pb exposure to IQ in<br />

subsequent analyses. Results evaluated by applying<br />

a random-effects model.<br />

Needleman and<br />

Gatsonis (1990)<br />

Meta analysis <strong>of</strong> 12 studies chosen on the basis <strong>of</strong><br />

quality—covariate assessment and application <strong>of</strong><br />

multiple regression techniques. Studies weighted on<br />

basis <strong>of</strong> sample size. Studies divided according to<br />

tissue analyzed (blood or teeth). Joint p-values and<br />

avg effect sizes calculated using two different<br />

methods.<br />

Schwartz (1994) Meta analysis <strong>of</strong> 7 recent studies relating blood Pb to<br />

IQ were reviewed, three longitudinal and four crosssectional.<br />

Measure <strong>of</strong> effect was estimated decrease<br />

in IQ <strong>for</strong> an increase in blood Pb from 10 to 20<br />

µg/dL. Studies were weighted by the inverse <strong>of</strong> the<br />

variances using random<br />

Umbilical cord blood Pb<br />

Serial postnatal blood Pb<br />

Lifetime avg blood Pb 12.4<br />

(range 4.1-34.8) µg/dL<br />

Blood Pb<br />

Tooth Pb<br />

Concurrent blood Pb level exhibited the strongest<br />

relationship with IQ, although results <strong>of</strong> regression analyses<br />

<strong>for</strong> all blood Pb variables were similar. Steepest declines in<br />

IQ were at blood Pb concentrations below 10 µg/dL. For<br />

the entire pooled data set, a decline <strong>of</strong> 6.2 IQ points (95%<br />

CI: 3.8, 8.6) was estimated <strong>for</strong> an increment in blood Pb<br />

from 1 to 10 µg/dL.<br />

Joint p-values <strong>for</strong> blood Pb studies were


AX6-10<br />

Table AX6-2.2 (cont’d). Meta- and Pooled-Analyses <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Pocock et al. (1994) Meta-analysis <strong>of</strong> five prospective and fourteen crosssectional<br />

studies (including tooth and blood tissues)<br />

were included. The fixed effect method <strong>of</strong><br />

Thompson and Pocock (1992) was employed.<br />

Only blood Pb at or near two yrs <strong>of</strong> age was<br />

considered <strong>for</strong> the prospective studies.<br />

Blood Pb<br />

Tooth Pb<br />

Overall conclusion was that a doubling <strong>of</strong> blood Pb levels<br />

from 10 to 20 µg/dL, or tooth Pb from 5 to 10 µg/g was<br />

associated with an avg estimated deficit in IQ <strong>of</strong> ~1-2<br />

points. Authors caution interpretation <strong>of</strong> these results and<br />

Pb literature in general, citing questions about<br />

representativeness <strong>of</strong> the samples, residual confounding,<br />

selection bias, and reverse causality.


AX6-11<br />

Table AX6-2.3. Cross-Sectional Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Lanphear et al. (2000)<br />

U.S.<br />

Emory et al. (2003)<br />

U.S.<br />

Chiodo et al. (2004)<br />

U.S.<br />

Europe<br />

Walkowiak et al.<br />

(1998)<br />

Germany<br />

Prpic-Majic et al.<br />

(2000)<br />

Croatia<br />

4,853 U.S. children ages six to 16 yrs enrolled in<br />

NHANES-<strong>II</strong>I. Two subtests <strong>of</strong> the WISC-R (Block<br />

Design and Digit Span) used to assess intellectual<br />

status. Medical and sociodemographic covariates were<br />

assessed<br />

77 healthy, lower-risk African-American infants age 7<br />

mos. The Fagan Test <strong>of</strong> Infant Intelligence (FT<strong>II</strong>) was<br />

administered to assess intellectual status. Birth weight<br />

and gestational age examined as potential<br />

covariates/confounders.<br />

237 African-American inner-city children assessed at<br />

7.5 yrs <strong>of</strong> age. Cohort was derived from a larger study<br />

<strong>of</strong> the effects <strong>of</strong> prenatal alcohol exposure on child<br />

development. 83% <strong>of</strong> children in Pb study had little or<br />

no gestational exposure to alcohol. WISC-<strong>II</strong>I was<br />

administered to assess intellectual status. Medical and<br />

sociodemographic covariates were assessed.<br />

384 six-yr-old children in three German cities. Two<br />

subtests <strong>of</strong> the WISC (Vocabulary and Block Design)<br />

used to estimate IQ. Both subscales were combined to<br />

<strong>for</strong>m a “WISC Index.” Medical and sociodemographic<br />

covariate covariates were assessed.<br />

275 3rd and 4th grade students in Zagreb, Croatia.<br />

WISC-R was administered to assess intellectual status.<br />

Covariate factors limited to parents’ educational status<br />

and gender <strong>of</strong> child.<br />

Blood Pb at time <strong>of</strong> testing<br />

Geometric blood Pb 1.9<br />

(SE 0.1) µg/dL<br />

2.1% with blood Pb<br />

∃10 µg/dL<br />

Maternal blood Pb<br />

Blood Pb 0.72 (SD 0.86)<br />

µg/dL<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 5.4 (SD 3.3)<br />

µg/dL<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 4.2 µg/dL<br />

95th percentile 8.9 µg/dL<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 7.1 (SD 1.8)<br />

µg/dL<br />

Multivariate analyses revealed a significant association<br />

between blood Pb levels and both WISC-R subtests.<br />

Associations remained statistically significant when<br />

analyses were restricted to children with blood Pb levels<br />

below 10 µg/dL. Authors caution that lack <strong>of</strong> control <strong>for</strong><br />

parental intelligence and variables like the HOME scale<br />

should temper any conclusions regarding observed effects.<br />

Infants scoring in the upper 5th to 15th percentiles <strong>for</strong> the<br />

FT<strong>II</strong> had mother with significantly lower maternal blood<br />

Pb levels when compared to those scoring in the lower<br />

5th or 15th percentile. Findings <strong>of</strong> this study should be<br />

considered preliminary due to small sample size and lack<br />

<strong>of</strong> covariate assessment or control.<br />

Following covariate adjustment statistically significant<br />

relationships between blood Pb and full-scale, verbal and<br />

per<strong>for</strong>mance IQ were observed. Significant effects <strong>of</strong> Pb<br />

on full-scale and per<strong>for</strong>mance IQ was evident at blood Pb<br />

concentrations below 7.5 µg/dL.<br />

Following covariate-adjustment, WISC Vocabulary was<br />

significantly associated with blood Pb but combined WISC<br />

index was borderline. Authors conclude that findings<br />

roughly correspond with those <strong>of</strong> other studies that find<br />

effects below 10 µg/dL but caution that potentially<br />

important covariates such as HOME scores were not<br />

controlled.<br />

Following covariate adjustment, no statistically significant<br />

associations were observed <strong>for</strong> Pb or other indicators <strong>of</strong><br />

toxicity (ALAD, EP) on WISC-R. Authors argue that<br />

study had sufficient power and that the “no-effect”<br />

threshold <strong>for</strong> Pb must be in the upper part or above the<br />

study’s range <strong>of</strong> exposures.


AX6-12<br />

Table AX6-2.3 (cont’d). Cross-Sectional Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Kordas et al. (2004,<br />

2006)<br />

Mexico<br />

Counter et al. (1998)<br />

Ecuador<br />

Asia<br />

Rabinowitz et al.<br />

(1991)<br />

Taiwan<br />

Bellinger et al. (2005)<br />

India<br />

602 1st grade children in public schools in a highly<br />

industrialized area <strong>of</strong> northern Mexico. Premise <strong>of</strong><br />

study was that effects <strong>of</strong> Pb could be explained by<br />

correlated nutritional factors such as iron status,<br />

anemia, and growth. Peabody Picture Vocabulary<br />

Test-Revised (PPVT-R), Cognitive Abilities Test<br />

(CAT), and an abbreviated <strong>for</strong>m <strong>of</strong> the WISC-R were<br />

administered to assess intellectual status. Medical and<br />

sociodemographic covariates were assessed.<br />

77 chronically Pb-exposed children living in<br />

Ecuadorian villages where Pb is used extensively in<br />

commercial ceramics production. Ravens Colored<br />

Progressive Matrices (RCPM) used to index<br />

intellectual status. Only half <strong>of</strong> the sample was<br />

assessed. No assessment <strong>of</strong> medical or<br />

sociodemographic covariates.<br />

443 children in grades one to three in Taipei City and<br />

three schools near Pb smelters. Ravens Colored<br />

Progressive Matrices (RCPM) used to index<br />

intellectual status. Medical and sociodemographic<br />

covariate factors were assessed.<br />

74 four to fourteen yr-old children residing in Chennai,<br />

India were enrolled in the study, 31 <strong>of</strong> which were<br />

assessed with the Binet-Kamath Intelligence test. Data<br />

were collected on sociodemographic features <strong>of</strong><br />

subjects’ families.<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 11.5<br />

(SD 6.1) µg/dL<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 47.4 (SD 22)<br />

µg/dL<br />

Dentin tooth Pb<br />

Taipei City 4.3 (SD 3.7)<br />

µg/g<br />

Smelter areas 6.3 (SD 3.3)<br />

µg/g<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 11.1 (SD 5.6)<br />

µg/dL<br />

Following covariate adjustment blood Pb levels were<br />

significantly associated with poorer per<strong>for</strong>mance on the<br />

PPVT-R, WISC-R Coding, and Number and Letter<br />

Sequencing, a Math Achievement Test, and the Sternberg<br />

Memory Test. Authors concluded that Pb’s association<br />

with iron deficiency anemia or growth retardation could<br />

not explain relationship between Pb and cognitive<br />

per<strong>for</strong>mance. Non-linear analyses <strong>of</strong> selected<br />

neurocognitive outcomes revealed that dose-response<br />

curves were steeper at lower than at higher blood Pb<br />

levels. Moreover, the slopes appeared negative at blood<br />

Pb levels below 10 µg/dL, above which they tend to<br />

plateau. Effects <strong>of</strong> Pb on neurocognitive attainment<br />

appeared to be greatest among the least advantaged<br />

members <strong>of</strong> the cohort.<br />

Simple regression analysis revealed a correlation between<br />

blood Pb and RCPM <strong>of</strong> only borderline significance.<br />

Results difficult to interpret because there was no attempt<br />

to age-adjust. When analysis restricted to children 9 to<br />

11 yrs <strong>of</strong> age, a highly significant negative correlation was<br />

obtained. Study has little relevance to the question <strong>of</strong> Pb<br />

hazards in the U.S. because <strong>of</strong> unusually high levels <strong>of</strong><br />

exposure.<br />

Scores on the RCPM were negatively correlated with tooth<br />

Pb concentrations. In multivariate analyses, parental<br />

education was the most important predictor <strong>of</strong> RCPM<br />

scores, but tooth Pb concentrations still significantly<br />

predicted lower scores in females residing in low-income<br />

families.<br />

Covariate-adjusted blood Pb coefficient was negative but<br />

nonsignificant, perhaps due to small sample size and<br />

highly variable per<strong>for</strong>mance <strong>of</strong> subjects with the least<br />

elevated blood Pb concentrations.


AX6-13<br />

Table AX6-2.3 (cont’d). Cross-Sectional Studies <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Middle East<br />

Al-Saleh et al. (2001)<br />

Saudi Arabia<br />

533 Riyadh, Saudi Arabian girls (6-12 yrs <strong>of</strong> age) were<br />

administered a variety <strong>of</strong> standardized tests including<br />

the TONI, and the Beery VMI. Extensive data were<br />

collected on potentially confounding variables<br />

including sociodemographic variables, early<br />

developmental milestones and child health status.<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 8.1 (SD 3.5)<br />

µg/dL<br />

Blood Pb levels had no impact on TONI scores but this test<br />

has limited evidence <strong>of</strong> validity in this population.<br />

Significant negative associations were noted between<br />

blood Pb levels and the Beery VMI suggesting an<br />

association between impairment in visual-spatial skills in<br />

Saudi children with blood Pb levels in the range <strong>of</strong> 2.3 to<br />

27.4 µg/dL.


AX6-14<br />

Table AX6-2.4. Effects <strong>of</strong> <strong>Lead</strong> on Academic Achievement in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Lanphear et al. (2000)<br />

U.S.<br />

Needleman et al. (1990)<br />

U.S.<br />

Design: Cross-sectional. 4,853 U.S. children ages<br />

six to 16 yrs enrolled in NHANES-<strong>II</strong>I. Subjects<br />

were administered the Arithmetic and Reading<br />

subtests <strong>of</strong> the Wide Range Achievement Test-<br />

Revised (WRATR). A number <strong>of</strong> medical and<br />

sociodemographic covariates were assessed and<br />

entered into multivariable models.<br />

Design: Prospective cohort. Re-examination <strong>of</strong> the<br />

Chelsea and Somerville cohort recruited in the<br />

1970’s (Needleman et al., 1979). 132 adolescents<br />

were recalled. Large battery <strong>of</strong> tests was<br />

administered to examine neurobehavioral deficits<br />

and academic achievement in high school and shortly<br />

following graduation. Extensive assessment <strong>of</strong><br />

medical and sociodemographic covariates.<br />

Blood Pb at time <strong>of</strong> testing<br />

Geometric blood Pb 1.9<br />

(SE 0.1) µg/dL<br />

2.1% with blood Pb<br />

∃10 µg/dL<br />

Tooth (dentin) Pb<br />

Tooth Pb median 8.2 µg/g<br />

Following covariate adjustment, a statistically significant<br />

relationship between blood Pb and WRATR per<strong>for</strong>mance<br />

was found. A 0.70 point decrement in Arithmetic scores<br />

and a 1 point decrement in Reading scores <strong>for</strong> each<br />

1 µg/dL increase in blood Pb concentration was observed.<br />

Statistically significant inverse relationships between blood<br />

Pb levels and per<strong>for</strong>mance <strong>for</strong> both Reading and<br />

Arithmetic subtests were found <strong>for</strong> children with blood Pb<br />

concentrations 20 ppm were at higher risk<br />

<strong>of</strong> dropping out <strong>of</strong> high school (adjusted OR = 5.8 [95%<br />

CI: 1.4, 40.7]) and <strong>of</strong> having a reading disability (adjusted<br />

OR = 5.8 [95% CI: 1.7, 19.7]). Higher dentin Pb levels<br />

were also significantly associated with lower class<br />

standing, increased absenteeism, and lower vocabulary and<br />

grammatical reasoning scores on the Neurobehavioral<br />

Evaluation System (NES). Authors conclude that undue<br />

exposure to Pb has enduring and important effects on<br />

objective parameters <strong>of</strong> success in life.


AX6-15<br />

Table AX6-2.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Academic Achievement in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Bellinger et al. (1992)<br />

U.S.<br />

Leviton et al. (1993)<br />

U.S.<br />

Australia<br />

Fergusson et al. (1993,<br />

1997); Fergusson and<br />

Horwood (1993)<br />

New Zealand<br />

Design: Prospective longitudinal. 148 children in<br />

the Boston Pb Study cohort were examined at 10 yrs<br />

<strong>of</strong> age. The short-<strong>for</strong>m <strong>of</strong> the Kaufman Test <strong>of</strong><br />

Educational Achievement (KTEA) was used to assess<br />

academic achievement. Primary outcome was the<br />

Battery Composite Score. Extensive assessment <strong>of</strong><br />

medical and sociodemographic covariates.<br />

Design: Prospective cohort. Teachers <strong>of</strong> ~2000 eight<br />

yr-old children born in 1 hospital in Boston between<br />

1979 and 1980 filled out the Boston Teachers<br />

Questionnaire (BTQ) to assess academic<br />

per<strong>for</strong>mance and behavior. Limited in<strong>for</strong>mation is<br />

provided on the assessment <strong>of</strong> covariate factors but a<br />

number were considered and controlled <strong>for</strong> in<br />

multivariable analyses.<br />

Design: Prospective cohort. Academic per<strong>for</strong>mance<br />

was examined in a birth cohort <strong>of</strong> 1200 New Zealand<br />

children enrolled in the Christchurch Health and<br />

Development Study. Measures <strong>of</strong> academic<br />

per<strong>for</strong>mance at 12-13 yrs included the Brut Reading<br />

Test, Progressive Achievement Test, Test <strong>of</strong><br />

Scholastic Abilities, and teacher ratings <strong>of</strong> classroom<br />

per<strong>for</strong>mance in the areas <strong>of</strong> reading, writing, and<br />

mathematics. The growth <strong>of</strong> word recognition skills<br />

from 8 to 12 yrs was also examined using growth<br />

curve modeling methods. Academic achievement in<br />

relationship to Pb was re-examined in this cohort at<br />

18 yrs. Measures <strong>of</strong> academic achievement included<br />

the Burt Reading Test, number <strong>of</strong> yrs <strong>of</strong> secondary<br />

education, number <strong>of</strong> certificates passed (based on<br />

national examinations), and leaving school without<br />

<strong>for</strong>mal qualifications (failing to graduate). Extensive<br />

assessment <strong>of</strong> medical and social covariates.<br />

Cord and serial postnatal<br />

blood Pb assessments.<br />

Cord blood Pb grouping 10 µg/dL<br />

Blood Pb at 2 yrs 6.5<br />

(SD 4.9) µg/dL<br />

Cord blood Pb<br />

Cord blood Pb 6.8 µg/dL<br />

Tooth (dentin) Pb<br />

Tooth Pb 2.8 µg/g<br />

Tooth (dentin) Pb<br />

Tooth Pb 6.2 (SD 6.2) µg/g<br />

After covariate-adjustment, blood Pb levels at 24 mos were<br />

significantly predictive <strong>of</strong> lower academic achievement<br />

(∃ = !0.51, SE 0.20). Battery Composite Scores declined by<br />

8.9 points <strong>for</strong> each 10 µg/dL increase in blood Pb. This<br />

association was significant after adjustment <strong>for</strong> IQ. Authors<br />

conclude that Pb-sensitive neuropsychological processing and<br />

learning factors not reflected in measures <strong>of</strong> global intelligence<br />

may contribute to deficits in academic achievement.<br />

Following adjustment <strong>for</strong> potential confounding variables,<br />

elevated dentin Pb concentrations were associated with<br />

statistically significant reading and spelling difficulties as<br />

assessed by the BTQ among girls in the sample. Authors<br />

conclude that their findings support the case <strong>for</strong> Pb-associated<br />

learning problems at levels that were prevalent at that time in<br />

the general population. However, authors add that the inability<br />

to assess child-rearing quality in this study conducted by mail<br />

limits the inferences that can be drawn.<br />

Following covariate adjustment, dentin Pb levels were<br />

significantly associated with virtually every <strong>for</strong>mal index <strong>of</strong><br />

academic skills and teacher ratings <strong>of</strong> classroom per<strong>for</strong>mance<br />

in 12-13 yr-olds. After adjustment <strong>for</strong> covariates, tooth Pb<br />

levels greater than 8 µg/g were associated with significantly<br />

slow growth in word recognition abilities with no evidence <strong>of</strong><br />

catch up. At 18 yrs, tooth Pb levels were significantly<br />

associated with lower reading test scores, having a reading<br />

level <strong>of</strong> less than 12 yrs, failing to complete three yrs <strong>of</strong> high<br />

school, leaving school without qualifications, and mean<br />

number <strong>of</strong> School Certificates passed. Authors conclude that<br />

early exposure to Pb is independently associated with<br />

detectable and enduring deficits in children’s academic<br />

abilities. They further conclude that their findings are<br />

particularly significant in that they confirm the findings <strong>of</strong><br />

Needleman (1990), albeit in a cohort with lower levels <strong>of</strong><br />

exposure to environmental Pb.


AX6-16<br />

Table AX6-2.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Academic Achievement in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia<br />

Wang et al. (2002a)<br />

Taiwan<br />

Rabinowitz et al. (1992)<br />

Taiwan<br />

Middle East<br />

Al Saleh et al. (2001)<br />

Saudi Arabia<br />

Design: Cross-sectional. 934 3rd graders living in<br />

an urban industrial area <strong>of</strong> Taiwan. Outcome<br />

variables were grades <strong>for</strong> Chinese (reading, writing),<br />

mathematics, history, and natural science. Grades<br />

were converted into individual class rankings to<br />

avoid teacher bias. Limited data on medical and<br />

sociodemographic covariates.<br />

Design: Cross-sectional. Teachers <strong>of</strong> 493 children<br />

in grades 1-3 filled out the Boston Teachers<br />

Questionnaire (BTQ) to assess academic<br />

per<strong>for</strong>mance and behavior. Sociodemographic and<br />

medical covariate factors were assessed.<br />

Class rank, as assessed by the teacher, was examined<br />

in conjunction with blood Pb levels in 533 Riyadh,<br />

Saudi Arabian girls (6-12 yrs <strong>of</strong> age). Extensive data<br />

were collected on potentially confounding variables<br />

including sociodemographic variables, early<br />

developmental milestones and child health status.<br />

Blood Pb at time <strong>of</strong><br />

evaluation<br />

Blood Pb 5.5 (SD 1.9)<br />

µg/dL<br />

Tooth (dentin) Pb<br />

Tooth Pb 4.6 (SD 3.5) µg/g<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb 8.1 (SD 3.5)<br />

µg/dL<br />

Following covariate adjustment, blood Pb was significantly<br />

associated with lower class ranking in all academic<br />

subjects. Major shortcoming <strong>of</strong> this study is lack <strong>of</strong><br />

control <strong>for</strong> potentially important covariates such as<br />

parental IQ. However, the relatively low levels <strong>of</strong><br />

exposure in this sample and strength and consistency <strong>of</strong> the<br />

reported relationships suggest that Pb may be playing some<br />

role in lowering academic per<strong>for</strong>mance.<br />

Prior to adjustment <strong>for</strong> covariates, girls with higher<br />

exposures to Pb evinced a borderline significant trend <strong>for</strong><br />

reading difficulties while byes displayed significantly<br />

increased difficulties with respect to activity levels and<br />

task attentiveness. In logistic regression models that<br />

include significant covariate factors, the tooth Pb terms<br />

failed to achieve statistical significance. Authors conclude<br />

that Pb levels found in the teeth <strong>of</strong> children in this<br />

Taiwanese sample are not associated with learning<br />

problems as assessed by the BTQ.<br />

A significant inverse relationship between blood Pb levels<br />

and rank percentile scores was observed after adjusting <strong>for</strong><br />

a number <strong>of</strong> demographic and socioeconomic variables.<br />

When multiple regression models were fitted to a subset <strong>of</strong><br />

students with blood Pb levels below 10 µg/dL, class rank<br />

percentile continued to show a statistically significant<br />

association with blood Pb levels.


AX6-17<br />

Table AX6-2.5. Effects <strong>of</strong> <strong>Lead</strong> on Specific Cognitive Abilities in Children — Attention/Executive Functions, Learning, and<br />

Visual-spatial Skills<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Bellinger et al. (1994a)<br />

U.S.<br />

Stiles and Bellinger<br />

(1993)<br />

U.S.<br />

Canfield et al. (2003b,<br />

2004)<br />

U.S.<br />

Design: Prospective cohort. 79 subjects from the<br />

original Chelsea and Somerville, MA Pb study were<br />

re-evaluated at 19-20 yrs <strong>of</strong> age with the Mirsky<br />

battery <strong>of</strong> attentional measures. Extensive measures<br />

<strong>of</strong> medical and sociodemographic covariates.<br />

Design: Prospective longitudinal. 148 subjects from<br />

the Boston Pb Study were re-evaluated at 10 yrs <strong>of</strong><br />

age with an extensive neuropsychological battery.<br />

Tests included the Cali<strong>for</strong>nia Verbal Learning Test,<br />

Wisconsin Card Sorting Test, Test <strong>of</strong> Visual-Motor<br />

Integration, Rey-Osterieth Complex Figure, Story<br />

Recall, Finger Tapping, and Grooved Pegboard.<br />

Extensive measures <strong>of</strong> medical and<br />

sociodemographic covariates.<br />

Design: Prospective longitudinal. 170-174 children<br />

from the Rochester Pb Study were administered a<br />

number <strong>of</strong> learning and neuropsychological<br />

functioning at 48, 54, and 66 mos <strong>of</strong> age. At 48 and<br />

54 mos the Espy Shape School Task was<br />

administered while at 66 mos the Working Memory<br />

and Planning assessment protocols <strong>of</strong> the Cambridge<br />

Neuropsychological Test Automated Battery<br />

(CANTAB) was given. Extensive measures on<br />

medical and sociodemographic covariates.<br />

Tooth (dentin) Pb<br />

Tooth Pb 13.7 (SD 11.2)<br />

µg/g<br />

KXRF Bone Pb<br />

Tibial bone Pb<br />

(range 10) µg/g<br />

Patellar bone Pb<br />

(range 15) µg/g<br />

Cord and serial postnatal<br />

blood Pb assessments<br />

Cord blood Pb grouping 10 µg/dL<br />

Blood Pb at 2 yrs 6.5<br />

(SD 4.9) µg/dL<br />

Serial postnatal blood Pb<br />

Blood Pb at 2 yrs 9.7 µg/dL<br />

Lifetime avg blood Pb 7.2<br />

(range 0-20) µg/dL<br />

Higher tooth Pb concentrations were significantly<br />

associated with poorer scores on the Focus-Execute and<br />

Shift factors <strong>of</strong> the Mirsky battery. Few significant<br />

associations were observed between bone Pb levels and<br />

per<strong>for</strong>mance. Authors conclude that early Pb exposure<br />

may be associated with poorer per<strong>for</strong>mance on<br />

executive/regulatory functions, which are thought to<br />

depend on the frontal or prefrontal regions <strong>of</strong> the brain.<br />

Authors point out that the number <strong>of</strong> significant<br />

associations was about equal to those that would be<br />

expected by chance. However, tasks that assess attentional<br />

behaviors and executive functions tended to among those<br />

<strong>for</strong> which Pb was a significant predictor <strong>of</strong> per<strong>for</strong>mance.<br />

Following covariate adjustment, higher blood Pb<br />

concentrations at two yr were significantly associated with<br />

lower scores on Freedom from Distractibility factor <strong>of</strong> the<br />

Wechsler scales, increase in percentage <strong>of</strong> perseverative<br />

errors on the Wisconsin Card Sorting Test and the<br />

Cali<strong>for</strong>nia Verbal Learning Test.<br />

Following covariate adjustment, blood Pb level at 48 mos<br />

was negatively associated with children’s focused attention<br />

while per<strong>for</strong>ming the Shape School Tasks, efficiency at<br />

naming colors, and inhibition <strong>of</strong> automatic responding.<br />

Children with higher blood Pb concentrations also<br />

completed fewer phases <strong>of</strong> the Espy tasks and knew fewer<br />

color and shape names. On the CANTAB battery, children<br />

with higher lifetime avg blood Pb levels showed impaired<br />

per<strong>for</strong>mance on spatial working memory, spatial memory<br />

span, and cognitive flexibility and planning. Authors<br />

conclude that the effects <strong>of</strong> pediatric Pb exposure are not<br />

restricted to global measures <strong>of</strong> intellectual functioning and<br />

executive processes may be at particular risk.


AX6-18<br />

Table AX6-2.5 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Specific Cognitive Abilities in Children — Attention/Executive Functions,<br />

Learning, and Visual-spatial Skills<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Ris et al. (2004)<br />

U.S.<br />

Design: Prospective longitudinal. 195 subjects from<br />

the Cincinnati Pb Study were administered an<br />

extensive and comprehensive neuropsychological<br />

battery at 16-17 yrs <strong>of</strong> age. Domains assessed<br />

included Executive Functions, Attention, Memory,<br />

Achievement, Verbal Skills, Visuoconstructional,<br />

and Fine Motor. Factor scores trans<strong>for</strong>med to ranks<br />

derived from a principal components factor analysis<br />

<strong>of</strong> the neuropsychological test scores were the<br />

primary outcome variables. Extensive measures on<br />

medical and sociodemographic covariates.<br />

Prenatal (maternal) and<br />

serial postnatal blood Pb<br />

assessments<br />

Prenatal blood Pb 8.3<br />

(SD 3.7) µg/dL<br />

Blood Pb at 2 yrs 17.4<br />

(SD 8.8) µg/dL<br />

Following covariate adjustment, strongest associations<br />

between Pb exposure and per<strong>for</strong>mance were observed <strong>for</strong><br />

factor scores derived from the Attention component, which<br />

included high loadings on variables from the Conners<br />

Continuous Per<strong>for</strong>mance Test. This relationship was<br />

strongest in males. Authors speculate that since the<br />

incidence <strong>of</strong> Attention Deficit/Hyperactivity Disorder is<br />

greater in males in general, early exposure to Pb may<br />

exacerbate a latent potential <strong>for</strong> such problems.


AX6-19<br />

Table AX6-2.6. Effects <strong>of</strong> <strong>Lead</strong> on Disturbances in Behavior, Mood, and Social Conduct in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Sciarillo et al. (1992)<br />

U.S.<br />

Bellinger et al. (1994b)<br />

U.S.<br />

Denno (1990)<br />

U.S.<br />

Design: Cross-sectional. 150 2-5 yr-old children in<br />

Baltimore separated into “high” (2 consecutive blood<br />

Pb levels >15 µg/dL) and “low” groups. Mothers<br />

filled out the Achenbach Child Behavior Checklist<br />

(CBCL). The Center <strong>for</strong> Epidemiologic Studies<br />

Depression Scale (CESD) was administered to<br />

mothers as a control measure.<br />

Design: Prospective cohort: 1782 children born<br />

within a 1-yr period at a single Boston hospital were<br />

examined at 8 yrs <strong>of</strong> age. Teachers filled out the<br />

Achenbach Child Behavior Pr<strong>of</strong>ile (ACBP). Medical<br />

and sociodemographic characteristics assessed by<br />

questionnaire and chart review.<br />

Design: Prospective cohort. Survey <strong>of</strong> 987<br />

Philadelphia African-American youths enrolled in<br />

the Collaborative Perinatal Project. Data available<br />

from birth through 22 yrs <strong>of</strong> age. Analysis<br />

considered 100 predictors <strong>of</strong> violent and chronic<br />

delinquent behavior.<br />

Screening blood Pbs at<br />

various times be<strong>for</strong>e<br />

assessment<br />

High group 28.6<br />

(SD 9.3) µg/dL<br />

Low group 11.3<br />

(SD 4.3) µg/dL<br />

Umbilical cord blood Pb<br />

Cord blood Pb 6.8<br />

(SD 3.1) µg/dL<br />

Tooth (dentin) Pb<br />

Tooth Pb 3.4<br />

(SD 2.4) µg/g<br />

Blood Pb<br />

Values not provided<br />

When compared to lower exposed group, children in the<br />

high group had a significantly higher CBCL Total<br />

Behavior Problems Score (TBPS) and Internalizing and<br />

Externalizing scores. After adjustment <strong>for</strong> maternal<br />

depression, blood Pb concentrations were still significantly<br />

associated with an increase in the TBPS. Children in high<br />

group were nearly 3 times more likely to have a TBPS in<br />

the clinical range. A significantly higher percentage <strong>of</strong><br />

children in the high group scored in the clinical range <strong>for</strong><br />

CBCL subscales measuring aggressive and destructive<br />

behavioral tendencies.<br />

Cord blood Pb levels were not associated with the<br />

prevalence or nature <strong>of</strong> behavioral problems reported by<br />

teachers. Tooth Pb levels were significantly associated<br />

with ACBP Total Problem Behavior Scores (TPBS).<br />

Statistically significant tooth Pb-associated increases in<br />

both Externalizing and Internalizing scores were observed.<br />

Each log unit increase in tooth Pb was associated with a<br />

1.5-point increase in T scores <strong>for</strong> these scales. Authors<br />

caution that residual confounding cannot be ruled out<br />

because <strong>of</strong> the lack <strong>of</strong> in<strong>for</strong>mation on parental<br />

psychopathology or observations <strong>of</strong> the family<br />

environment. However, these results are in accord with<br />

other studies that social and emotional dysfunction may be<br />

an important expression <strong>of</strong> elevated Pb levels during early<br />

childhood.<br />

Repeat <strong>of</strong>fenders presented consistent features such as low<br />

maternal education, prolonged male-provider<br />

unemployment, frequent moves, and higher Pb<br />

intoxication. In male subjects, a history <strong>of</strong> Pb poisoning<br />

was among the most significant predictors <strong>of</strong> delinquency<br />

and adult criminality.


AX6-20<br />

Table AX6-2.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Disturbances in Behavior, Mood, and Social Conduct in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Needleman et al.<br />

(1996)<br />

U.S.<br />

Dietrich et al. (2001)<br />

U.S.<br />

Needleman et al.<br />

(2002)<br />

U.S.<br />

Design: Prospective cohort. 850 boys enrolled in the<br />

Pittsburgh Youth Study were prescreened to assess<br />

delinquent behavioral tendencies. Subjects who<br />

scored in the 30th percentile on the risk score and an<br />

equal number randomly selected from the remainder<br />

<strong>for</strong>m the sample <strong>of</strong> 530 subjects. Measures <strong>of</strong><br />

antisocial behavior were administered at 7 and 11 yrs<br />

<strong>of</strong> age including the Self Reported Antisocial Behavior<br />

scale (SRA), Self Report <strong>of</strong> Delinquent Behavior<br />

(SRD), and parents’ and teachers’ versions <strong>of</strong> the<br />

Achenbach Child Behavior Pr<strong>of</strong>ile (CBCL). Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

Design: Prospective longitudinal. 195 subjects from<br />

the Cincinnati Pb Study were examined at 16-17 yrs <strong>of</strong><br />

age. Parents were administered a questionnaire<br />

developed specifically <strong>for</strong> the study while CLS<br />

subjects were given the Self Report <strong>of</strong> Delinquent<br />

Behavior. Extensive assessment <strong>of</strong> medical and<br />

sociodemographic covariates.<br />

Design: Case-control. 194 adjudicated delinquents<br />

and 146 non-delinquent controls recruited from high<br />

schools in the City <strong>of</strong> Pittsburgh and Allegheny<br />

County, PA. Covariate assessments were not<br />

extensive but did include race, parental<br />

sociodemographic factors, and neighborhood crime<br />

rates.<br />

Bone Pb by K-XRF<br />

Bone Pb (exact<br />

concentrations not reported)<br />

Negative values treated<br />

categorically as 1 and<br />

positive values grouped into<br />

quintiles.<br />

Prenatal (maternal) and<br />

serial postnatal blood Pb<br />

assessments.<br />

Prenatal blood Pb 8.3<br />

(SD 3.7) µg/dL<br />

Blood Pb at 2 yrs 17.4<br />

(SD 8.8) µg/dL<br />

Bone Pb by KXRF<br />

Cases 11.0 (SD 32.7) µg/g<br />

Controls 1.5 (SD 32.1) µg/g<br />

Following covariate-adjustment, parents <strong>of</strong> subjects with<br />

higher Pb levels in bone reported significantly more<br />

somatic complaints, more delinquent and aggressive<br />

behavior, and higher Internalizing and Externalizing<br />

scores. Teachers reported significant increase in scores on<br />

somatic complaints, anxious/depressed, social problems,<br />

attention problems, delinquent behavior, aggressive<br />

behavior, internalizing and externalizing problems in the<br />

higher bone Pb subjects. At 11 yrs, subject’s SRD scores<br />

were also significantly related to bone Pb levels. More<br />

high Pb subjects had CBCL T scores in the clinical range<br />

<strong>for</strong> attention, aggression, and delinquency. Authors<br />

conclude that Pb exposure is associated with increased risk<br />

<strong>for</strong> antisocial and delinquent behavior.<br />

Prenatal (maternal) blood Pb was significantly associated<br />

with a covariate-adjusted increase in the frequency <strong>of</strong><br />

parent-reported delinquent and antisocial acts. Prenatal<br />

and measures <strong>of</strong> postnatal Pb exposure were significantly<br />

associated with self-reported delinquent and antisocial<br />

behaviors. Authors concluded that Pb might play a<br />

measurable role in the development <strong>of</strong> behavioral problems<br />

in inner-city children independent <strong>of</strong> other important social<br />

and biomedical c<strong>of</strong>actors.<br />

Cases had significantly higher avg concentrations <strong>of</strong> Pb in<br />

tibia than controls. Following covariate adjustment,<br />

adjudicated delinquents were 4 times more likely to have<br />

bone Pb concentration >25 µg/g then controls. Bone Pb<br />

level was the second strongest factor in the logistic<br />

regression models, exceeded only by race. In models<br />

stratified by race, bone Pb was exceeded as a risk factor<br />

only by single parent status. Authors conclude that<br />

elevated body Pb burdens are associated with increased<br />

risk <strong>for</strong> adjudicated delinquency.


AX6-21<br />

Table AX6-2.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Disturbances in Behavior, Mood, and Social Conduct in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Wasserman et al.<br />

(1994)<br />

Yugoslavia<br />

Australia<br />

Burns et al. (1999)<br />

Australia<br />

Fergusson et al. (1993)<br />

New Zealand<br />

Design: Prospective longitudinal. Birth cohort<br />

<strong>of</strong> ~300-400 infants followed since birth<br />

residing in two towns in Kosovo, Yugoslavia,<br />

one group near a longstanding Pb smelter and<br />

battery manufacturing facility and another in a<br />

relatively unexposed location 25 miles away.<br />

379 children at 3 yrs <strong>of</strong> age were examined.<br />

Parents were interviewed with the Achenbach<br />

Child Behavior Checklist (CBCL). Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

covariates.<br />

Design: Prospective longitudinal. 322 subjects<br />

residing in and near Port Pirie, Australia and<br />

followed since birth were re-evaluated at 11-13<br />

yrs <strong>of</strong> age. Parents completed the Achenbach<br />

Child Behavior Checklist. Extensive<br />

assessment <strong>of</strong> medical and sociodemographic<br />

characteristics.<br />

Design: Prospective cohort. 690-891 children<br />

ages 12 and 13 yrs from the Christchurch Child<br />

and Health Study, New Zealand were examined.<br />

Mothers and teachers were asked to respond to<br />

a series <strong>of</strong> items derived from the Rutter and<br />

Conners parental and teacher questionnaires.<br />

Extensive assessment <strong>of</strong> sociodemographic and<br />

medical covariates.<br />

Maternal prenatal, umbilical cord<br />

and serial postnatal blood Pb<br />

Maternal blood Pb in exposed<br />

area 19.9(SD 7.7) µg/dL,<br />

unexposed area 5.6<br />

(SD 2.0) µg/dL<br />

Umbilical cord blood Pb in<br />

exposed area 22.2<br />

(SD 8.1) µg/dL,<br />

unexposed area 5.5<br />

(SD 3.3) µg/dL<br />

Blood Pb at 2 yrs in exposed area<br />

35.4 µg/dL, unexposed area<br />

8.5 µg/dL<br />

Maternal prenatal, umbilical cord<br />

and serial postnatal blood Pb<br />

Antenatal avg blood<br />

Pb 10.1 (SD 3.9) µg/dL<br />

Umbilical cord blood Pb<br />

9.4 (SD 3.9) µg/dL<br />

Blood Pb at 2 yrs<br />

geometric mean 21.3<br />

(SD 1.2) µg/dL<br />

Tooth (dentine) Pb<br />

Tooth Pb range 3–12 µg/g<br />

Following covariate adjustment, concurrent blood Pb levels<br />

were associated with increased Destructive Behaviors on the<br />

CBCL subscale, although the variance accounted <strong>for</strong> by Pb<br />

was small compared to sociodemographic factors. As blood<br />

Pb increased from 10 to 20 µg/dL, subscale scores increased<br />

by 0.5 points. The authors conclude that while statistically<br />

significant, the contribution <strong>of</strong> Pb to social behavioral<br />

problems in this cohort was small compared to the effects <strong>of</strong><br />

correlated social factors.<br />

After adjustment <strong>for</strong> covariates, regression models revealed<br />

that <strong>for</strong> an increase in avg lifetime blood Pb concentrations<br />

from 10 to 30 µg/dL, the Externalizing behavior problem T<br />

score increased by 3.5 points in boys (95% CI: 1.6, 5.4), but<br />

only 1.8 points (95% CI: !0.1, 11.1) in girls. Internalizing<br />

behavior problems were predicted to rise by 2.1 points (95%<br />

CI: 0.0, 4.2) in girls by only 0.8 (95% CI: !0.9, 2.4) in boys.<br />

Authors concluded that Pb exposure is associated with an<br />

increase in externalizing (undercontrolled) behaviors in boys.<br />

Statistically significant dose-effect relationships were<br />

observed between tooth Pb levels and the<br />

inattention/restlessness variable at each age. Authors<br />

conclude that this evidence is consistent with the view that<br />

mildly elevated Pb levels are associated with small but long<br />

term deficits in attentional behaviors.


AX6-22<br />

Table AX6-2.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Disturbances in Behavior, Mood, and Social Conduct in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Australia<br />

Silva et al. (1988)<br />

New Zealand<br />

As part <strong>of</strong> the 11-yr follow-up <strong>of</strong> the Dunedin<br />

Multidisciplinary Health and Development Study, a<br />

longitudinal study <strong>of</strong> a birth cohort <strong>of</strong> children born<br />

in Dunedin’s only obstetric hospital, blood Pb levels<br />

were measured in 579 children at age 11 yrs old.<br />

The study sample was over-representative <strong>of</strong> higher<br />

SES, but was found to be representative <strong>of</strong> Dunedin<br />

children in educational attainment. Blood Pb levels<br />

were examined in association with intelligence<br />

assessed using the WISC-R and behavioral problems<br />

as assessed by both parents and teachers.<br />

Blood Pb at time <strong>of</strong> testing<br />

Blood Pb at age 11 yrs 11.1<br />

(SD 4.91, range 4-50) µg/dL<br />

Log blood Pb levels were significantly correlated with most<br />

measures <strong>of</strong> behavioral problems, including the Parents’ and<br />

Teachers’ Rutter Behavioral Scale, the Parents’ and<br />

Teachers’ Hyperactivity Scale, and the Teachers’ Inattention<br />

Scale, after adjustment <strong>for</strong> various potential confounders. No<br />

associations were observed between log blood Pb levels and<br />

IQ. Authors concluded that exposure to Pb is associated with<br />

increases in children’s’ general behavioral problems,<br />

especially in inattention and hyperactivity.


AX6-23<br />

Table AX6-2.7. Effects <strong>of</strong> <strong>Lead</strong> on Sensory Acuities in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Schwartz and Otto<br />

(1991)<br />

U.S.<br />

Dietrich et al. (1992)<br />

U.S.<br />

Europe<br />

Osman et al. (1999)<br />

Poland<br />

Design: Cross-sectional. 3545 subjects 6-19 yrs old<br />

who participated in the Hispanic Health and<br />

Nutrition Examination Survey. Pure tone<br />

audiometric evaluations were per<strong>for</strong>med at 500 Hz,<br />

2000 Hz, and 4000 Hz. Extensive measures on<br />

medical and sociodemographic covariates.<br />

Design: Prospective/longitudinal. 215 subjects<br />

drawn from the Cincinnati Pb Study at the age <strong>of</strong> 5<br />

yrs. Children were administered the SCAN-a<br />

standardized test <strong>of</strong> central auditory processing.<br />

Extensive measurement <strong>of</strong> medical and<br />

sociodemographic covariates<br />

Design: Cross-sectional. 155 children 4-14 yr-old<br />

living in an industrial region <strong>of</strong> Poland. Pure tone<br />

audiometric evaluations were per<strong>for</strong>med at 500 Hz,<br />

1000 Hz, 2000 Hz, 4000 Hz, 6000Hz, and 8000 Hz.<br />

Basic data on medical history, limited in<strong>for</strong>mation on<br />

sociodemographic covariates such as family<br />

structure and income.<br />

Blood Pb at the time <strong>of</strong><br />

testing<br />

Blood Pb 50th percentile<br />

8 µg/dL<br />

Prenatal (maternal) and serial<br />

postnatal blood Pb<br />

assessments<br />

Prenatal blood Pb 8.3<br />

(SD 3.7) µg/dL<br />

Blood Pb at 2 yrs 17.4 (SD<br />

8.8) µg/dL<br />

Blood Pb at the time<br />

<strong>of</strong> testing<br />

Blood Pb median 7.2<br />

(range 1.9-28) µg/dL<br />

Following covariate adjustment, higher blood Pb<br />

concentrations were associated with an increased risk <strong>of</strong><br />

hearing thresholds that were elevated above the standard<br />

reference level at all four frequencies. Blood Pb was also<br />

associated higher hearing threshold when treated as a<br />

continuous outcome. These relationships extended to blood<br />

Pb levels below 10 µg/dL. An increase in blood Pb from 6 to<br />

18 µg/dL was associated with a 2-dB loss at all frequencies.<br />

Authors conclude that HHANES results those reported<br />

earlier <strong>for</strong> NHANES-<strong>II</strong>.<br />

Higher prenatal (maternal), neonatal and postnatal blood Pb<br />

concentrations were associated with more incorrect<br />

identification <strong>of</strong> common monosyllabic words presented<br />

under conditions <strong>of</strong> muffling. Following covariate<br />

adjustment, avg childhood blood Pb level remained<br />

significantly associated with impaired per<strong>for</strong>mance on the<br />

SCAN subtest. Authors conclude that Pb-related deficits in<br />

hearing and auditory processing may be one plausible<br />

mechanism by which an increased Pb burden might impede a<br />

child’s learning.<br />

Higher blood Pb concentrations were significantly associated<br />

with increased hearing thresholds at all frequencies studied.<br />

This relationship remained significant when analyses were<br />

limited to subjects with blood Pb levels below 10 µg/dL.<br />

Authors conclude that auditory function in children is<br />

impaired at blood Pb concentrations below 10 µg/dL.


AX6-24<br />

Table AX6-2.8. Effects <strong>of</strong> <strong>Lead</strong> on Neuromotor Function in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Dietrich et al. (1993b);<br />

Bhattacharya et al.<br />

(1995); Ris et al.<br />

(2004)<br />

U.S.<br />

Europe<br />

Wasserman et al.<br />

(2000a)<br />

Yugoslavia<br />

Design: Prospective longitudinal. Relationship<br />

between Pb exposure and neuromotor function has<br />

been examined in several studies on the Cincinnati Pb<br />

Study Cohort from 6 to 17 yrs <strong>of</strong> age. At 6 yrs <strong>of</strong> age<br />

245 subjects were administered the Bruininks-<br />

Oseretsky Test <strong>of</strong> Motor Pr<strong>of</strong>iciency (BOTMP); at 6-<br />

10 yrs <strong>of</strong> age subjects were assessed <strong>for</strong> postural<br />

instability using a microprocessor-based strain gauge<br />

plat<strong>for</strong>m system and at 16-17 yrs <strong>of</strong> age the finemotor<br />

skills <strong>of</strong> study subjects were assessed with the<br />

grooved pegboard and finger tapping tasks (part <strong>of</strong> a<br />

comprehensive neuropsychological battery).<br />

Extensive measurement <strong>of</strong> medical and<br />

sociodemographic factors.<br />

Design: Prospective longitudinal. Birth cohort <strong>of</strong><br />

~300-400 infants followed since birth residing in two<br />

towns in Kosovo, Yugoslavia, one group near a<br />

longstanding Pb smelter and battery manufacturing<br />

facility and another in a relatively unexposed location<br />

25 miles away. 283 children at age 54 mos were<br />

administered the Beery Developmental Test <strong>of</strong><br />

Visual-Motor Integration (VMI) and the Bruininks-<br />

Oseretsky Test <strong>of</strong> Motor Pr<strong>of</strong>iciency (BOTMP).<br />

Extensive measurement <strong>of</strong> medical and<br />

sociodemographic factors.<br />

Prenatal (maternal) and<br />

serial postnatal blood Pb<br />

assessments<br />

Prenatal blood Pb 8.3<br />

(SD 3.7) µg/dL<br />

Blood Pb at 2 yrs 17.4 (SD<br />

8.8) µg/dL<br />

Maternal prenatal, umbilical<br />

cord and serial postnatal<br />

blood Pb<br />

Maternal blood Pb in<br />

exposed area 19.9<br />

(SD 7.7) µg/dL,<br />

unexposed area 5.6<br />

(SD 2.0) µg/dL<br />

Umbilical cord blood Pb in<br />

exposed area 22.2<br />

(SD 8.1) µg/dL,<br />

unexposed area 5.5<br />

(SD 3.3) µg/dL<br />

Blood Pb at 2 yrs in exposed<br />

area 35.4 µg/dL, unexposed<br />

area 8.5 µg/dL<br />

Following covariate adjustment, postnatal Pb exposure was<br />

significantly associated with poorer scores on BOTMP<br />

measures <strong>of</strong> bilateral coordination, visual-motor control,<br />

upper-limb speed and dexterity and the Fine Motor<br />

Composite score. Low-level neonatal blood Pb<br />

concentrations were also significantly associated with poorer<br />

scores on the a<strong>for</strong>ementioned subtests, as well as measures<br />

<strong>of</strong> visual-motor control. Postnatal Pb exposure was<br />

significantly associated with greater postural instability in 6-<br />

10 yr-old subjects and poorer fine-motor coordination when<br />

examined at 16-17 yrs.<br />

Authors conclude that effects <strong>of</strong> early Pb exposure extend<br />

into a number <strong>of</strong> dimensions <strong>of</strong> neuromotor development.<br />

Following covariate-adjustment, the log avg <strong>of</strong> serial blood<br />

Pb assessments to 54 mos was associated with lower Fine<br />

Motor Composite and VMI scores. Pb exposure was<br />

unrelated to gross motor per<strong>for</strong>mance. With covariate<br />

adjustment, an increase in avg blood Pb from 10 to 20 µg/dL<br />

was associated with a loss <strong>of</strong> 0.62 and 0.42 points<br />

respectively, in Fine Motor Composite and VMI. Authors<br />

noted that other factors such as indicators <strong>of</strong> greater<br />

stimulation in the home make a larger contribution to motor<br />

development than Pb.


AX6-25<br />

Table AX6-2.9. Effects <strong>of</strong> <strong>Lead</strong> on Direct Measures <strong>of</strong> Brain Anatomical Development and Activity in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Trope et al. (1998)<br />

U.S.<br />

Trope et al. (2001)<br />

U.S.<br />

Cecil et al. (2005)<br />

U.S.<br />

Design: Case-control. One 10 yr-old subject with<br />

history <strong>of</strong> Pb poisoning and unexposed 9 yr-old<br />

cousin. Magnetic Resonance Imaging (MRI) and<br />

Magnetic Resonance Spectroscopy (MRS) were<br />

used to assess differences in cortical structures and<br />

evidence <strong>of</strong> neuronal loss. This was the first study<br />

to attempt to determine in vivo structural and/or<br />

metabolic differences in the brain <strong>of</strong> a child<br />

exposed to Pb compared with a healthy control.<br />

Design: Case-control. 16 subjects with a history <strong>of</strong><br />

elevated blood Pb levels be<strong>for</strong>e 5 yrs <strong>of</strong> age and<br />

5 age-matched siblings or cousins were evaluated.<br />

Avg age at time <strong>of</strong> evaluation was 8 yrs. Magnetic<br />

Resonance Imaging (MRI) and Magnetic<br />

Resonance Spectroscopy (MRS) were used to<br />

assess differences in cortical structures and<br />

evidence <strong>of</strong> neuronal loss.<br />

Design: Prospective/longitudinal. 48 young adults<br />

ages 20 to 23 yrs were re-examined. Functional<br />

MRI (fMRI) was used to examine the influence <strong>of</strong><br />

childhood Pb exposure on language function.<br />

Subjects per<strong>for</strong>med a verb generation/fingertapping<br />

paradigm. Extensive measurement <strong>of</strong><br />

medical and sociodemographic covariates<br />

Blood Pb<br />

Pb poisoned case 51 µg/dL<br />

at 38 mo<br />

Unexposed control not<br />

reported.<br />

Blood Pb<br />

Range in Pb-exposed 23 to<br />

65 µg/dL<br />

Controls


AX6-26<br />

Table AX6-2.9 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Direct Measures <strong>of</strong> Brain Anatomical Development and Activity in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Rothenberg et al. (2000)<br />

Mexico<br />

Asia<br />

Meng et al. (2005)<br />

China<br />

Design: Prospective/longitudinal. 113 5-7 yr-old<br />

children from the Mexico City Prospective Study<br />

were re-examined. Brain stem auditory evoked<br />

potentials were recorded to assess the impact <strong>of</strong><br />

prenatal and postnatal Pb exposure on development<br />

<strong>of</strong> auditory pathways. Results adjusted <strong>for</strong> gender<br />

and head circumference.<br />

Design: Case-control. 6 subjects with blood Pb<br />

concentrations ∃27 µg/dL and 6 controls with<br />

blood Pb concentrations


AX6-27<br />

Table AX6-2.10. Reversibility <strong>of</strong> <strong>Lead</strong>-related Deficits in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Ruff et al. (1993)<br />

U.S.<br />

Rogan et al. (2001);<br />

Dietrich et al. (2004)<br />

U.S.<br />

Design: Intervention study, non-randomized.<br />

126 children with complete data age 13 to 87 mos<br />

and with blood Pb levels between 25 and 55 µg/dL<br />

were given chelation with ETDA and/or therapeutic<br />

iron where indicated. At baseline and follow-up,<br />

patients were evaluated with the Bayley Scales <strong>of</strong><br />

Infant Development, Mental Development Index,<br />

or Stan<strong>for</strong>d Binet Scales <strong>of</strong> Intelligence depending<br />

upon age.<br />

Design: Double blind, placebo-controlled<br />

randomized clinical trial. The Treatment <strong>of</strong> Pb-<br />

Exposed Children (TLC) clinical trial <strong>of</strong> 780<br />

children in 4 centers was designed to determine if<br />

children with moderately elevated blood Pb<br />

concentrations given succimer would have better<br />

neuropsychological outcomes than children given<br />

placebo. Children between 12 and 33 mos <strong>of</strong> age<br />

were evaluated 3 yrs following treatments and<br />

again at 7 and 7.5 yrs <strong>of</strong> age. A wide range <strong>of</strong><br />

neurological, neuropsychological, and behavioral<br />

tests was administered. Assessment <strong>of</strong> potentially<br />

confounding factors included sociodemographics<br />

and parental IQ.<br />

Blood Pb at time <strong>of</strong><br />

treatment<br />

Blood Pb 31.2 (SD 6.5)<br />

µg/dL<br />

Blood Pb<br />

Baseline blood Pb 26<br />

(SD 26.5) µg/dL in both<br />

drug and placebo groups<br />

Without respect to treatment regimen, changes in<br />

per<strong>for</strong>mance on cognitive measures after 6 mos were<br />

significantly related to changes in blood Pb levels after<br />

control <strong>for</strong> confounding factors. Standardized scores on tests<br />

increased 1 point <strong>for</strong> every 3 µg/dL decrement in blood Pb.<br />

Succimer was effective in lowering blood Pb levels in<br />

subjects on active drug during the first 6 mos <strong>of</strong> the trial.<br />

However, after 1 yr differences in the blood Pb levels <strong>of</strong><br />

succimer and placebo groups had virtually disappears.<br />

3 yrs following treatment, no statistically significant<br />

differences between active drug and placebo groups were<br />

observed <strong>for</strong> IQ or other more focused neuropsychological<br />

and behavioral measures. When evaluated at 7 and 7.5 yrs <strong>of</strong><br />

age, TLC could demonstrate no benefits <strong>of</strong> earlier treatment<br />

on an extensive battery <strong>of</strong> cognitive, neurological, behavioral<br />

and neuromotor endpoints. Authors conclude that the TLC<br />

regimen <strong>of</strong> chelation therapy is not associated with<br />

neurodevelopmental benefits in children with blood Pb levels<br />

between 20 and 44 µg/dL and that these results emphasize<br />

the importance <strong>of</strong> taking environmental measures to prevent<br />

exposure to Pb in light <strong>of</strong> the apparent irreversibility <strong>of</strong> Pbassociated<br />

neurodevelopmental deficits.


AX6-28<br />

Table AX6-2.10 (cont’d). Reversibility <strong>of</strong> <strong>Lead</strong>-related Deficits in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Liu et al. (2002)<br />

U.S.<br />

Latin America<br />

Kordas et al. (2005);<br />

Rico et al. (2006)<br />

Mexico<br />

Australia<br />

Tong et al. (1998)<br />

Australia<br />

Design: Prospective longitudinal clinical trial.<br />

Data from the Treatment <strong>of</strong> Pb-Exposed Children<br />

(TLC) used to examine prospective relationships<br />

between falling blood Pb levels and changes in<br />

cognitive functioning. 741 children recruited<br />

between 13 and 33 mos <strong>of</strong> age were assessed at<br />

baseline and 6 mos later with the Bayley Mental<br />

Development Index (MDI) and 36 mos postrandomization<br />

with the Wechsler Preschool and<br />

Primary Scales <strong>of</strong> Intelligence-Revised to<br />

obtain IQ.<br />

Design: Double-blind, placebo-controlled<br />

nutritional supplementation clinical trial conducted<br />

among 602 1st grade children ages 6-8 yrs in<br />

Torreón, Mexico. Subjects received iron, zinc,<br />

both or placebo <strong>for</strong> 6 mos. Parents and teachers<br />

filled out the Conners Rating Scales at baseline and<br />

follow-up six mos following the end <strong>of</strong><br />

supplementation to index behavioral changes<br />

following therapy. In addition, 11 cognitive tests<br />

<strong>of</strong> memory, attention, visual-spatial abilities, and<br />

learning were administered, including WISCR-M at<br />

baseline and follow-up 6 mos later.<br />

Design: Prospective longitudinal. 375 children<br />

from the Port Pirie Prospective Study were<br />

followed from birth to the age <strong>of</strong> 11-13 yrs. Bayley<br />

Mental Development Index (MDI) at 2 yrs, the<br />

McCarthy Scales General Cognitive Index (GCI)<br />

and IQs from the Wechsler Intelligence Scale<br />

served as the primary indicators <strong>of</strong> intellectual<br />

status. The purpose <strong>of</strong> the study was to assess the<br />

reversibility <strong>of</strong> Pb effects on cognition in<br />

relationship to declines in blood Pb over time.<br />

Blood Pb<br />

Baseline blood Pb 26.2<br />

(SD 5.1) µg/dL<br />

36 mos post-randomization<br />

blood Pb 12.2 (SD 5.2)<br />

µg/dL<br />

Blood Pb<br />

Baseline blood Pb 11.5<br />

(SD 6.1) µg/dL<br />

Postnatal blood Pb<br />

Mean blood Pb at 2 yrs<br />

21.2 µg/dL declining to<br />

7.9 µg/dL at 11-13 yrs<br />

TLC found no overall effect <strong>of</strong> changing blood Pb level on<br />

change in cognitive test scores from baseline to 6 mos.<br />

Slope estimated to be 0.0 points per 10 µg/dL change in<br />

blood Pb. From baseline to 36 mos and 6 mos to 36 mos,<br />

falling blood Pb levels were significantly associated with<br />

increased cognitive test scores, but only because <strong>of</strong> an<br />

association in the placebo group. Authors conclude that<br />

because improvements were not observed in all children, the<br />

data do not provide support that Pb-induced cognitive<br />

impairments are reversible. Although the possible<br />

neurotoxicity <strong>of</strong> succimer cannot be ruled out.<br />

No significant effects <strong>of</strong> treatment on behavior or cognition<br />

could be detected with any consistency. Authors conclude<br />

that this regimen <strong>of</strong> supplementation does not result in<br />

improvements in ratings <strong>of</strong> behavior or cognitive<br />

per<strong>for</strong>mance.<br />

Although blood Pb levels declined substantially, covariate<br />

adjusted scores on standardized measures <strong>of</strong> intellectual<br />

attainment administered at 2, 4, 7, and 11-13 yrs <strong>of</strong> age were<br />

unrelated to declining body burden. Authors conclude that<br />

effects <strong>of</strong> early exposure to Pb during childhood are not<br />

reversed by a subsequent decline in blood Pb concentration.


ANNEX TABLES AX6-3<br />

AX6-29


AX6-30<br />

Table AX6-3.1. Neurobehavioral Effects Associated with Environmental <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Krieg et al. (2005)<br />

1988-1994<br />

U.S.<br />

Muldoon et al. (1996)<br />

U.S.<br />

4,937 adults aged 20-59 yrs from<br />

NHANES <strong>II</strong>I completed three<br />

neurobehavioral tests. Regression analyses<br />

<strong>of</strong> neurobehaqvioral test and log <strong>of</strong> blood<br />

Pb concentration adjusted <strong>for</strong> sex, age<br />

education, family income, race/ethnicity,<br />

computer or video game familiarity,<br />

alcohol use, test language, and survey<br />

phase.<br />

325 women from rural location (mean age<br />

71) and 205 women from a city location<br />

(mean age 69) participants in the Study <strong>for</strong><br />

Osteoporotic Fractures had the association<br />

<strong>of</strong> nonoccupational Pb exposure and<br />

cognitive function examined. Logistic<br />

regression determined effect <strong>of</strong> blood Pb<br />

on neuropsychological per<strong>for</strong>mance.<br />

Mean blood Pb 3.3 µg/dL<br />

Range 0.7 to 41.7 µg/dL<br />

Rural group<br />

Blood Pb 5 µg/dL<br />

Urban group<br />

Blood Pb 5 µg/dL<br />

No statistically significant relationship between blood Pb concentration<br />

and mean simple reaction time, symbol-digit substitution latency and<br />

errors and serial digit learning trials to criterion and total score after<br />

adjustments <strong>for</strong> covariates.<br />

Groups were significantly different with the urban group more educated<br />

and smoked and drank more. Per<strong>for</strong>mance in each group stratified by<br />

exposure into three groups (low 7 µg/dL rural and >8 µg/dL) — no significant associations were<br />

present in the urban group but the rural group had significantly poorer<br />

per<strong>for</strong>mance with increasing blood Pb <strong>for</strong> Trails B (OR = 2.6 [95% CI:<br />

1.04, 6.49]), Digit Symbol (OR = 3.73 [95% CI: 1.57, 8.84]),and<br />

Reaction Time in the lower (OR = 2.84 [95% CI: 1.19, 6.74]) and<br />

upper extremities (OR = 2.43 [95% CI: 1.01, 5.83]). The fact that<br />

marked differences exist between the low Pb groups <strong>for</strong> rural and urban<br />

(the lowest 15th percentile) suggests the differences between the two<br />

groups are unrelated to Pb. Response time <strong>for</strong> reaction time across Pb<br />

groups increased <strong>for</strong> the rural group and decreased or remained the<br />

same <strong>for</strong> the urban group. As response time is sensitive to Pb effect,<br />

this raises question whether factors not measured accounted <strong>for</strong><br />

difference. Namely MMSE <strong>for</strong> the whole population was 25 (15-26)<br />

with poorer per<strong>for</strong>mance in the rural group. The clinical cut<strong>of</strong>f score<br />

<strong>for</strong> MMSE is 24 suggesting the presence <strong>of</strong> clinical cognitive disorders.<br />

Even though this is a simple neuropsychological battery up to 9 were<br />

unable to per<strong>for</strong>m some <strong>of</strong> the tests including 3 on the MMSE.


AX6-31<br />

Table AX6-3.1 (cont’d). Neurobehavioral Effects Associated with Environmental <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Payton et al. (1998)<br />

U.S.<br />

Rhodes et al. (2003)<br />

U.S.<br />

Wright et al. (2003)<br />

U.S.<br />

141 healthy men in VA normal aging study<br />

evaluated every 3 to 5 yrs with cognitive<br />

battery and blood Pb and once a<br />

measurement <strong>of</strong> patella and tibia bone Pb.<br />

Statistics are confusing as it is not clear<br />

when ANCOVA is used and how the<br />

groups are created.<br />

526 participants with mean age 67 yrs,<br />

47% had education level <strong>of</strong> high school or<br />

less. Mood symptoms evaluated with Brief<br />

Symptom Inventory (BSI). Use <strong>of</strong> logistic<br />

regression adjusting <strong>for</strong> covariates<br />

examined association <strong>of</strong> BSI scales and<br />

blood Pb and bone Pb levels.<br />

736 healthy men (mean age 68) in<br />

Normative Aging Study examined every 3<br />

to 5 yrs were administered the Mini-<br />

Mental State Exam (MMSE). Linear<br />

regression examined relationship <strong>of</strong><br />

MMSE and blood Pb, patella and tibia<br />

bone Pb measurements after adjusting <strong>for</strong><br />

covariates.<br />

Mean blood Pb 6 µg/dL<br />

Mean patella bone Pb 32<br />

µg/g<br />

Mean tibia bone Pb 23 µg/g<br />

bone mineral<br />

Mean blood Pb 6 µg/dL<br />

Mean tibia Pb 22 µg/g<br />

Mean patella Pb 32 µg/g<br />

Mean blood Pb 5 µg/dL,<br />

Mean patella bone Pb 30<br />

µg/g<br />

Mean tibia bone Pb 22 µg/g<br />

Regressions adjusted <strong>for</strong> age and education found significant<br />

relationship <strong>of</strong> blood Pb with Pattern Comparison (perceptual speed),<br />

Vocabulary, Word List Memory, Constructional Praxis, Boston<br />

Naming Test, and Verbal Fluency Test. Only <strong>for</strong> Constructional Praxis<br />

were bone Pb and blood Pb significantly associated. Mechanism most<br />

sensitive to low levels Pb exposure believed to be response speed.<br />

Vocabulary is significantly associated with blood Pb. Education is<br />

negatively correlated to bone and blood Pb. It is not clear how multiple<br />

comparisons were handled<br />

BSI found mood symptoms <strong>for</strong> anxiety and depression were potentially<br />

associated with bone Pb levels. Education was inversely related to<br />

bone Pb and high school graduates had significantly higher odds <strong>of</strong><br />

Global Severity Index and Positive Symptom Total.<br />

Mean MMSE score 27. Relation <strong>of</strong> MMSE scores


AX6-32<br />

Table AX6-3.1 (cont’d). Neurobehavioral Effects Associated with Environmental <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Weisskopf et al.<br />

(2004b)<br />

U.S.<br />

Europe<br />

Nordberg et al. (2000)<br />

Sweden<br />

466 men, mean age 70 yrs, in the VA<br />

Normative Aging Study had 2 MMSE tests<br />

3.5 yrs apart.<br />

762 participants, mean age 88 yrs, in a study<br />

<strong>of</strong> aging and dementia examined MMSE.<br />

Used blood Pb as dependent and examined<br />

contribution <strong>of</strong> covariates and MMSE.<br />

Mean blood Pb 4 µg/dL<br />

Mean patella bone Pb 23<br />

µg/g<br />

Mean tibia bone Pb 19 µg/g<br />

Baseline mean MMSE score was 27 and mean change in MMSE<br />

score over 3.5 yrs was 0.3. Change in MMSE associated with one<br />

interquartile range increment <strong>for</strong> bone Pb and blood Pb found<br />

relationship between patella Pb and change in MMSE was unstable<br />

when patella Pb is ∃90 µg/g bone mineral. Examination <strong>of</strong> patella Pb<br />

below this level found a greater inverse association with MMSE at<br />

lower Pb concentrations (∃ = !0.25 [95% CI: !0.45, !0.05]). A similar<br />

but weaker association existed <strong>for</strong> tibia Pb when values ∃67 µg/g<br />

bone mineral were removed (∃ = !0.19 [95% CI: !0.39, 0.02]). There<br />

was no association <strong>of</strong> MMSE change and blood Pb (∃ = !0.01 [95%<br />

CI: !0.13, 0.11]). There was no interaction <strong>of</strong> age and bone Pb.<br />

These are very high bone Pb levels <strong>for</strong> environmental exposure. The<br />

biological plausibility <strong>of</strong> change in the MMSE over 3.5 yrs would<br />

have been rein<strong>for</strong>ced if the change by functional domain in the<br />

MMSE was provided.<br />

Mean blood Pb 3.7 µg/dL Mean MMSE 25 found no relation <strong>of</strong> blood Pb and MMSE. In this<br />

population was fairly homogenous, all elderly Swedes, and the<br />

likelihood <strong>of</strong> prior exposure to elevated Pb levels was low.


AX6-33<br />

Table AX6-3.2. Symptoms Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada<br />

Lindgren et al. (1999)<br />

Canada<br />

Holness et al. (1988)<br />

Canada<br />

Europe<br />

Lucchini et al. (2000)<br />

Italy<br />

Smelter workers (n = 467) with a mean age<br />

<strong>of</strong> 40 yrs completed the Pr<strong>of</strong>ile <strong>of</strong> Mood<br />

Scale. Factor structure <strong>of</strong> POMS validated in<br />

this occupational population. Regression<br />

analysis determined association with Pb<br />

exposure.<br />

47 demolition workers with acute Pb<br />

intoxication - Phase 1 - were followed with<br />

blood Pb and symptoms during engineering<br />

modifications to control exposure –<br />

Phases 2-4. Workers stratified by blood Pb<br />

and symptom frequency was analyzed.<br />

66 workers in Pb manufacturing, mean age<br />

40 (8.7) yrs and 86 controls mean age 43<br />

(8.8) yrs were administered a questionnaire<br />

with neuropsychological (14 items), sensorymotor<br />

(3 items), memory (4 items) and<br />

extrapyramidal (8 items), 10 Parkinson<br />

symptoms and the Mood Scale. Group<br />

comparisons and linear regression examined<br />

relationship <strong>of</strong> symptoms and Pb exposure.<br />

Mean (SD, range) blood Pb<br />

28 (8.5, 4-62) µg/dL<br />

Mean (SD, range) IBL 711<br />

(415.5, 1-1537) µg·yr/dL<br />

Phase I - Mean blood Pb<br />

59 µg/dL<br />

Phase 2 - Mean blood Pb<br />

30 µg/dL<br />

Phase 3 - Mean blood Pb<br />

19 µg/dL<br />

Phase 4 - Mean blood Pb<br />

17 µg/dL<br />

Pb workers<br />

Mean (SD, range) blood Pb<br />

27 (11.0, 6-61) µg/dL<br />

Mean (SD, range) TWA 32<br />

(14.1, 6-61) µg/dL<br />

Mean (SD, range) IBL 410<br />

(360.8, 8-1315) µg·yr/dL<br />

Controls<br />

Mean (SD, range) blood Pb<br />

8 (4.5, 2-21) µg/dL<br />

Factor analysis found one factor labeled “general distress” composed<br />

<strong>of</strong> POMS subscales anger, confusion, depression, fatigue and tension<br />

and a second factor labeled ‘psychological adjustment.’ IBL was<br />

significantly associated with ‘general distress’ after adjustment <strong>for</strong> the<br />

covariates (�∃ = 0.28 [SE 1.51 Η 10 !4 ], p = 0.01) while there was no<br />

relation with blood Pb. The factor structure <strong>of</strong> POMS originally<br />

validated in a clinical population had six mood subscales however the<br />

factor structure in this occupational population was found to have<br />

only two subscales.<br />

Below blood Pb 70 µg/dL. Of interest, at beginning <strong>of</strong> Phase 4 when<br />

mean blood Pb was 13 µg/dL, no symptoms were reported. At the<br />

end <strong>of</strong> Phase 4, mean blood Pb was 17 µg/dL and one worker<br />

complained <strong>of</strong> fatigue.<br />

Pb exposed worker reported confusion, somnolence, abnormal<br />

fatigue, irritability, and muscular pain more frequently (p < 0.04).<br />

There were no group differences <strong>for</strong> the parkinsonism symptoms or<br />

Mood Scale. Linear regression combing exposed and control group<br />

found neurological symptoms significantly associated with blood Pb<br />

r = 0.22, p = 0.006). Neuropsychological symptoms were<br />

significantly higher in the High-IBL compared to the Low-IBL group.<br />

The estimated threshold <strong>for</strong> a significant increase (prevalence <strong>of</strong> 5%)<br />

<strong>of</strong> a high score <strong>for</strong> neurological symptoms was at a blood Pb <strong>of</strong><br />

12 µg/dL.


AX6-34<br />

Table AX6-3.2 (cont’d). Symptoms Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Maizlish et al. (1995)<br />

Venezuela<br />

Asia<br />

Schwartz et al.<br />

(2001a)<br />

Korea<br />

Lee et al. (2000)<br />

Korea<br />

43 workers from a Pb smelter, mean age 34<br />

(9) yrs and 47 nonexposed workers, mean<br />

age 35 (11) yrs completed the pr<strong>of</strong>ile <strong>of</strong><br />

mood states (POMS) questionnaire and a<br />

questionnaire <strong>of</strong> symptoms <strong>of</strong> the central and<br />

peripheral nervous system, and<br />

gastrointestinal. Prevalence ratios used to<br />

examine symptoms and Pb. ANCOVA and<br />

linear regression adjusting <strong>for</strong> potential<br />

confounders examined relationship <strong>of</strong> Pb<br />

exposure and POMS.<br />

803 Pb-exposed Korean workers, mean age<br />

40 yrs completed the Center <strong>for</strong><br />

Epidemiologic Studies Depression Scale.<br />

Linear regression examined <strong>for</strong> association<br />

<strong>of</strong> CES-D and Pb biomarkers after adjusting<br />

<strong>for</strong> the covariates.<br />

95 Korean Pb exposed workers, mean age 43<br />

yrs, completed questionnaire <strong>of</strong> Pb-related<br />

symptoms present over last three mos.<br />

Relationship between symptom score and<br />

measures <strong>of</strong> Pb exposure assessed by linear<br />

regression. Logistic regression use to model<br />

presence or absence <strong>of</strong> symptoms <strong>for</strong><br />

gastrointestinal, neuromuscular, and general.<br />

Pb workers<br />

Mean (SD) blood Pb 43<br />

(12.1) µg/dL<br />

Mean (SD) peak blood Pb<br />

60 (20.3) µg/dL<br />

Mean (SD) TWA 48 (12.1)<br />

µg/dL<br />

Controls<br />

Mean (SD) blood Pb 15 (6)<br />

µg/dL<br />

Mean (SD) peak blood Pb<br />

15 (6) µg/dL<br />

Mean (SD) TWA 15 (SD 6)<br />

µg/dL<br />

Mean (SD) blood Pb 32<br />

(15.0) µg/dL<br />

Mean (SD) tibia Pb 37<br />

(40.3) µg/g bone mineral<br />

DMSA-chelatable Pb Mean<br />

(SD) 289 (167.7) µg<br />

Mean (SD) ZPP 108 (60.6)<br />

µg/dL<br />

Mean (SD) ALAU3 (2.8)<br />

mg/L<br />

Mean(SD) blood Pb 45<br />

(SD 9.3) µg/dL<br />

Significantly increased relative risks found <strong>for</strong> difficulty<br />

concentrating (RR = 1.8 [95% CI: 1.0, 3.1]), <strong>of</strong>ten being angry or<br />

upset without reason (RR = 2.2 [95% CI: 1.2, 4.1]), feeling<br />

abnormally tired (RR = 2.2 [95% CI: 0.9, 5.3]) and joint pain<br />

(RR = 1.8 [95% CI: 1.0, 3.3]). The six subscales <strong>of</strong> the POMS were<br />

not significantly different between the exposed and control groups.<br />

However dose-related analysis found significantly poorer scores <strong>for</strong><br />

tension-anxiety and blood Pb (p = 0.009), hostility and blood Pb<br />

(p = 0.01) and TWA (p = 0.04), and depression and blood Pb<br />

(p = 0.003) and peak Pb (p = 0.003) and TWA (p = 0.004).<br />

After adjustment <strong>for</strong> age, gender and education significant<br />

associations found <strong>for</strong> CES-D and tibia Pb (∃ = 0.0021 [SE 0.0008];<br />

p < 0.01) but not with blood Pb. This occupational Pb-exposed<br />

populations had higher past Pb exposure compared to the current<br />

mean blood Pb <strong>of</strong> 32 µg/dL.<br />

Workers with DMSA-chelatable Pb above the median <strong>of</strong> 261 µg were<br />

6.2 (95% CI: 2.4, 17.8) times more likely to have tingling or<br />

numbness in their extremities, 3.3 (95% CI: 1.2, 10.5) times more<br />

likely to experience muscle pain and 3.2 (95% CI: 1.3, 7.9) times<br />

more likely to feel irritable. The workers with higher chelatable Pb<br />

were 7.8 (95% CI: 2.8, 24.5) times more likely to experience<br />

neuromuscular symptoms compared to workers with lower chelatable<br />

Pb. In this study ZPP predicted weakness <strong>of</strong> ankle and wrist<br />

(OR = 2.9 [95% CI: 1.1, 8.1]) and fatigue (OR = 2.9 [95% CI:<br />

1.1, 8.7]) while ALAU predicted inability to sleep (OR = 5.4 [95%<br />

CI: 1.2, 33.2]) and blood Pb was not significantly associated with any<br />

symptoms. A measure <strong>of</strong> Pb in bioavailable storage pools was the<br />

strongest predictor <strong>of</strong> symptoms particularly neuromuscular.


AX6-35<br />

Table AX6-3.2 (cont’d). Symptoms Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Niu et al. (2000)<br />

China<br />

44 Pb-exposed workers (17 men, 27 women)<br />

from Pb printing houses, mean age 35 (4.9)<br />

and education 9.3 (no SD) yrs and 34<br />

controls (19 men and 15 women), mean age<br />

33 (7.4) yrs and education 9.5 (no SD) yrs<br />

completed the pr<strong>of</strong>ile <strong>of</strong> mood state as part <strong>of</strong><br />

the NCTB. ANCOVA controlling <strong>for</strong> age,<br />

sex and education examined group<br />

differences and linear regression <strong>for</strong> doseresponse<br />

relationship.<br />

Mean blood Pb 29<br />

(SD 26.5) µg/dL<br />

(8 workers blood Pb<br />

exceeded 50 µg/dL)<br />

Controls<br />

Mean blood Pb 13<br />

(SD 9.9) µg/dL<br />

(1 control blood Pb<br />

exceeded 50 µg/dL)<br />

POMS subscales <strong>for</strong> confusion (F = 3.02, p < 0.01), fatigue (F = 3.61,<br />

p < 0.01), and tension (F = 2.82, p < 0.01) were significantly elevated<br />

in the Pb exposed group. Regression analyses found a dose response<br />

(data not shown).


AX6-36<br />

Table AX6-3.3. Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Fiedler et al. (2003)<br />

New Jersey<br />

Canada<br />

Lindgren et al. (1996)<br />

Canada<br />

40 workers with Pb exposure, mean age<br />

48 (9.5) yrs completed a neurobehavioral<br />

battery and was compared to 45 Pb/solvent<br />

workers, mean age 47 (10.2), 39 solvent<br />

exposed workers, mean age 43 (9.4), and<br />

33 controls, mean age 44 (10.2). Group<br />

differences and dose-effect relationships<br />

were assessed after adjusting <strong>for</strong> potential<br />

confounding.<br />

467 Canadian <strong>for</strong>mer and current, French<br />

and English speaking Pb smelter workers,<br />

mean age 43 (11.0) yrs and education<br />

10 (3.2) yrs were administered a<br />

neuropsychological battery in English or<br />

French. Data analyses used MANCOVA<br />

adjusting <strong>for</strong> age, education, measure <strong>of</strong><br />

depressive symptoms and self reported<br />

alcohol use.<br />

Mean (SD) blood Pb<br />

µg/dL; mean (SD) bone Pb<br />

ppm (dry weight)<br />

Pb workers<br />

14 (11.7); 2.7 (0.7)<br />

Pb/Solvent workers<br />

12 (11.6); 2.8 (0.6)<br />

Solvent workers<br />

5 (4.1); !1.8 (1.8)<br />

Controls<br />

4 (1.4); !1.1 (1.6)<br />

Mean (SD) yrs employment<br />

18 (7.4)<br />

Mean (SD) blood Pb 28<br />

(8.4) µg/dL<br />

Mean (SD) TWA 40<br />

(4-66) µg/dL<br />

Mean (SD) IBL 765<br />

(1-1626) µg·yr/dL<br />

Of nineteen outcomes, significant differences found on the Cali<strong>for</strong>nia<br />

verbal learning test (CVLT) (p = 0.05) and positive symptom distress<br />

index on the Symptom checklist-90-R. On the CVLT the controls<br />

per<strong>for</strong>med significantly better on trials 2 and 3 demonstrating<br />

efficiency <strong>of</strong> verbal learning. Symbol digit substitution (SDS)<br />

approached significance (p = 0.09) with Pb and Pb/solvent group<br />

slower on latency <strong>of</strong> response but not accuracy. Bone Pb was a<br />

significant predictor <strong>of</strong> latency <strong>of</strong> response on SDS, total errors on<br />

paced auditory serial addition task and simple reaction time nonpreferred<br />

hand. Bone Pb and SRT, preferred hand approached<br />

significance. This is a confusing study design as bone Pb is used as a<br />

predictor in workers both with and without occupational Pb exposure.<br />

Fourteen neuropsychological variables examined by MANCOVA<br />

with the grouping variable exposure (high, medium and low) and the<br />

covariates, age, education, CES-D, and alcohol use found no exposure<br />

term significant until yrs <strong>of</strong> employment, a suppressor term, was<br />

added as a covariate. IBL exposure groups differed significantly (df<br />

2,417) on digit symbol (F = 3.03, p = 0.05), logical memory (F = 3.29,<br />

P = 0.04), Purdue dominant hand (F = 4.89, p = 0.01), and trails A<br />

(F = 3.89, p = 0.02) and B (F = 3.2, p = 0.04). This study showed a<br />

dose-effect relationship between cumulative Pb exposure (IBL) and<br />

neuropsychological per<strong>for</strong>mance at a time when there was no<br />

association with current blood Pb.


AX6-37<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada (cont’d)<br />

Bleecker et al. (2002)<br />

Canada<br />

Bleecker et al. (2005a)<br />

Canada<br />

256 smelter workers from the above<br />

population were currently employed and<br />

took the test battery in English. Their mean<br />

age was 41 (7.9) yrs, and education 10 (2.8)<br />

yrs. The goal was to determine if<br />

educational achievement as measured by<br />

WRAT-R Reading modified per<strong>for</strong>mance on<br />

MMSE. Linear regression assessed the<br />

contribution <strong>of</strong> age, WRAT-R, education,<br />

alcohol intake, cigarette use, IBL and<br />

IBLΗWRAT-R on MMSE per<strong>for</strong>mance.<br />

256 smelter workers currently employed and<br />

took the test battery in English. Their mean<br />

age was 41 (7.9) yrs, and education 10 (2.8)<br />

yrs. The purpose was to determine whether<br />

components <strong>of</strong> verbal memory as measured<br />

on the Rey Auditory Verbal Learning Test<br />

(RAVLT) were differentially affected by Pb<br />

exposure. Linear regression and ANCOVA<br />

assessed the relationship <strong>of</strong> Pb and<br />

components <strong>of</strong> verbal learning and memory.<br />

Mean (SD) blood Pb 28<br />

(8.8) µg/dL<br />

Mean (SD) IBL 725 (434)<br />

µg·yr/dL<br />

Mean (SD) blood Pb 28<br />

(8.8) µg/dL<br />

Mean (SD) TWA 39 (12.3)<br />

µg/dL<br />

Mean (SD) IBL 725 (434)<br />

µg·yr/dL<br />

MMSE had a median (range) score <strong>of</strong> 29 (19-30). The most common<br />

errors were recall <strong>of</strong> 3 items (38%), spell world backwards (31%),<br />

repetition <strong>of</strong> “no ifs ands or buts” (21%) and copy a design to two<br />

intersecting pentagons (16%). WRAT-R reading used as an additional<br />

measure <strong>of</strong> educational achievement because it was a stronger predictor<br />

<strong>of</strong> MMSE per<strong>for</strong>mance than yrs <strong>of</strong> education. The significant<br />

interaction (♠R 2 = 2%, p = 0.01) explained by a dose-effect between<br />

IBL and MMSE only in the 78 workers with a WRAT-R reading grade<br />

level less than 6. The workers with higher reading grade levels and the<br />

same cumulative Pb exposure were able to compensate <strong>for</strong> the effects<br />

<strong>of</strong> Pb on the MMSE because <strong>of</strong> increased cognitive reserve.<br />

Outcome variables RAVLT a word list test included measures <strong>of</strong><br />

immediate memory span and attention (Trial 1), best learning (Trial V),<br />

incremental learning across the five trials (Total Score), and storage<br />

(Recognition) and retrieval (Delayed Recall) <strong>of</strong> verbal material. TWA<br />

significantly contributed to the explanation <strong>of</strong> variance <strong>for</strong> Trial V<br />

(♠R 2 = 1.4%, p < 0.03) and Delayed Recall (♠R 2 = 1.4%, p = 0.03)<br />

after adjusting <strong>for</strong> age and WRAT-R while IBL did the same with<br />

Recognition (♠R 2 = 2.0%, p =


AX6-38<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada (cont’d)<br />

Bleecker et al. (1997a)<br />

New Brunswick<br />

1992-1993<br />

Bleecker et al. (1997b)<br />

New Brunswick<br />

1992-1993<br />

The per<strong>for</strong>mance <strong>of</strong> the 467 current and retired<br />

smelter workers as described in Lindgren et al.<br />

(1996) administered a screening<br />

neuropsychological battery by testers blinded<br />

to the degree <strong>of</strong> Pb exposure <strong>of</strong> the worker had<br />

their per<strong>for</strong>mance compared to age matched<br />

norms. If per<strong>for</strong>mance on two or more tests in<br />

any functional domain was below 1.5 standard<br />

deviations the worker was invited <strong>for</strong> a<br />

complete clinical evaluation. Eighty current<br />

workers were identified by this criterion.<br />

Mean yrs - age 44 (8.4) yrs, education 8 (2.8)<br />

yrs and duration employed 20 (5.3) yrs. Five<br />

neuropsychological tests commonly associated<br />

with Pb exposure were examined <strong>for</strong> a<br />

differential association with blood Pb,<br />

IBL,TWA and bone Pb.<br />

Of the 80 current smelter workers described<br />

above 78 completed a simple visual reaction<br />

time (SRT) and had mean yrs age 44 (8.2) yrs,<br />

education 8 (7.2) yrs and duration employed<br />

20 (5.6) yrs.<br />

Mean (SD) blood Pb 26<br />

(7.07) µg/dL<br />

Mean (SD) TWA 42<br />

(8.4) µg/dL<br />

Mean (SD) IBL 903<br />

(305.9) µg·yr/dL,<br />

Mean (SD) tibial bone Pb<br />

41 µg/g bone mineral<br />

Mean (SD) blood Pb, 26<br />

(7.2) µg/dL<br />

Mean (SD) blood Pb from<br />

bone 7 (4.2) µg/dL<br />

Mean (SD) blood Pb from<br />

environment 19<br />

(7.0) µg/dL<br />

Mean (SD) bone Pb 40<br />

(25.2) µg/g bone mineral<br />

Relationship <strong>of</strong> 5 neuropsychological tests with 4 measures <strong>of</strong> Pb dose<br />

after adjusting <strong>for</strong> age age 2 and education, education 2 found RAVLT trial<br />

V and Verbal Paired Associates were associated with blood Pb<br />

(♠R 2 = 6.2%, p = 0.02; ♠R 2 = 5.5%, p = 0.07) and TWA (♠R 2 = 3.2%,<br />

p = 0.09; ♠R 2 = 13.9%; P = 0.00) while Digit Symbol and Grooved<br />

Pegboard were associated with TWA (♠R 2 = 6.1%, p = 0.00; ♠R 2 = 5.5%,<br />

p = 0.02) and IBL (♠R 2 = 4.8%, p = 0.01; ♠R 2 = 5.7%, p = 0.02). Only<br />

grooved pegboard was associated with bone Pb (♠R 2 = 4.2%, p = 0.05).<br />

Block design was not associated with any measures <strong>of</strong> Pb dose. Age was<br />

an effect modifier with grooved pegboard. There was enhanced slowing in<br />

older workers when compared to younger workers with the identical IBL.<br />

SRT consisted <strong>of</strong> 44 responses to a visual stimulus at interstimulus<br />

intervals (ISI) varying between 1 through 10 seconds with a mean SRT<br />

(median) <strong>of</strong> 262 (179 to 387) ms. Blood Pb and median SRT had a<br />

curvilinear relationship R 2 = Pb + Pb 2 , 13.7%, p < 0.01) after adjusting <strong>for</strong><br />

age and education with slowing <strong>of</strong> SRT beginning at a blood Pb <strong>of</strong><br />

~30 µg/dL. No relationship existed between bone Pb and SRT. There was<br />

a stronger association between Pb and Pb 2 and SRT <strong>for</strong> the longer ISIs <strong>of</strong> 6<br />

to 10 seconds (R 2 = 13.9%, p < 0.01), as age was significantly related to<br />

the shorter ISI = s but not the longer ones. In this population the<br />

contribution <strong>of</strong> bone Pb to blood Pb had been previously where estimated<br />

where <strong>for</strong> a bone Pb level <strong>of</strong> 100 µg Pb/g bone mineral, 17 µg Pb/dL <strong>of</strong> the<br />

blood Pb was derived from internal bone stores with the remainder from<br />

the environment. Blood Pb was fractionated to that from bone (blood Pbbn)<br />

vs. blood Pb from the environment (blood Pb-en). Regression analysis<br />

to examine the relationship <strong>of</strong> blood Pb-bn and blood Pb-en and SRT after<br />

adjusting <strong>for</strong> the covariates found significant contribution to the variance<br />

<strong>of</strong> SRT only <strong>for</strong> blood Pb-en (R 2 <strong>for</strong> blood Pb-en + blood Pb-en 2 = 14.4%,<br />

p < 0.01). The absence <strong>of</strong> a contribution by age and more stable responses<br />

with ISIs <strong>of</strong> 6 to 10 sec supports using this component <strong>of</strong> SRT.


AX6-39<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada (cont’d)<br />

Lindgren et al. (2003)<br />

New Brunswick<br />

1992-1993<br />

Braun and Daigneault<br />

(1991)<br />

Quebec<br />

In an attempt to separate the effects <strong>of</strong> past<br />

high Pb exposure from a lower proximate<br />

exposure, examination <strong>of</strong> the pattern <strong>of</strong> Pb<br />

levels <strong>of</strong> the 467 Canadian Pb smelter<br />

workers found 40 workers who had high past<br />

exposure followed by yrs where 90% <strong>of</strong><br />

blood Pb were above 40 µg/dL (High-<br />

High = H-H) while another group <strong>of</strong> 40<br />

workers had similar past high Pb exposure<br />

followed by yrs where 90% <strong>of</strong> blood Pb were<br />

below 40 µg/dL (High-Low = H-L). The<br />

groups did not differ on age, education, yrs<br />

<strong>of</strong> employment or CES-D. Five outcomes<br />

examined-Purdue Pegboard assembly,<br />

Block Design, Digit Symbol, Rey Auditory<br />

Verbal Learning Test-total score, delayed<br />

Logical Memory.<br />

41 workers from a secondary Pb smelter,<br />

mean age 35 (9.6) yrs and yrs <strong>of</strong> education<br />

10 (2.1) were compared to a control group<br />

mean age 37 (10.1) yrs and yrs <strong>of</strong> education<br />

11 (1.3) on tests <strong>of</strong> cognitive and motor<br />

function. MANCOVA and dose-effect<br />

relationships after adjusting <strong>for</strong> potential<br />

confounders were per<strong>for</strong>med.<br />

Mean (SD) IBL <strong>for</strong> past<br />

exposure<br />

H-H 633 (202.2) µg·yr/dL<br />

H-L 557 (144.8) µg·yr/dL<br />

Mean (SD) IBL <strong>for</strong> the<br />

proximate exposure<br />

H-H 647 (58.7) µg·yr/dL<br />

H-L 409 (46.4) µg·yr/dL<br />

Mean (SD) blood Pb<br />

H-H 37 (5.1) µg/dL<br />

H-L 24 (5.2) µg/dL<br />

Mean (SD) TWA 53<br />

(7.5) µg/dL<br />

Mean (SD) maximum<br />

blood Pb 87 (22.4) µg/dL<br />

Of the five neuropsychological measures examined only RAVLT<br />

(total score) and Logical Memory (delayed) were significantly<br />

different after adjusting <strong>for</strong> the covariates in the two pattern groups.<br />

Use <strong>of</strong> regression analyses found pattern group contributed<br />

significantly (R 2 = 4%, p < 0.05) to the explanation <strong>of</strong> variance in<br />

RAVLT after accounting <strong>for</strong> current blood Pb (R 2 = 3%, p < 0.10) and<br />

IBL measures (R 2 = 7%, p < 0.01). For past IBL, H-H pattern<br />

correlated more strongly with RAVLT (r = !0.21) while H-L pattern<br />

had no relationship with past exposure (r = 0.08). For proximate IBL<br />

the difference was maintained between H-H (r = !0.11) and H-L<br />

pattern (r = 0.00). The authors suggested that the absence <strong>of</strong> an<br />

association between past high Pb exposure and verbal memory in the<br />

H-L pattern group may reflect reversibility <strong>of</strong> function when blood Pb<br />

is maintained below 40 µg/dL.<br />

None <strong>of</strong> the measures <strong>of</strong> cognitive executive function showed group<br />

differences. Partial correlation adjusting <strong>for</strong> age and education with<br />

dose related variables found no statistical significance. On motor<br />

function the exposed workers had significantly slower simple reaction<br />

time (p = 0.05). However partial correlations with measures <strong>of</strong> dose<br />

found dose-effect correlation in both negative and positive directions.<br />

Group <strong>of</strong> exposed workers was mixed <strong>for</strong> Pb exposure with 11<br />

currently working and the remainder with no exposure up to 84 mos.<br />

Also two <strong>of</strong> the exposed workers had been treated with chelation.


AX6-40<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

H≅nninen et al. (1998)<br />

Finland<br />

Lucchini et al. (2000)<br />

Italy<br />

Fifty-four Pb battery workers were<br />

stratified by those whose blood Pb never<br />

exceeded 50 µg/dL (n = 26) (group 1)<br />

and those who had higher exposure in the<br />

past (n = 28) (group 2) to examine the<br />

neuropsychological effects <strong>of</strong> current low<br />

level blood Pb from higher blood Pb in<br />

the past. Mean age group 1was 42 (9.3)<br />

yrs, education 8 (1.7) yrs and yrs <strong>of</strong><br />

exposure 12 (6.7). Mean age group 2 was<br />

47 (6.2) yrs, education 8 (1.0) yrs and yrs<br />

<strong>of</strong> exposure 21 (6.9). Analysis included<br />

partial correlations within the groups and<br />

ANCOVA within group 1 divided at the<br />

median TWA3 <strong>of</strong> 29 µg/dL.<br />

66 workers in Pb manufacturing, mean<br />

age 40 (8.6) yrs, mean education 8 ( 2.4)<br />

yrs and mean exposure time 11 (9) yrs<br />

and a control group <strong>of</strong> 86 with mean age<br />

43 (8.8) yrs, mean yrs <strong>of</strong> education 9<br />

(2.7) yrs. Group differences examined<br />

and dose-effect relationship with<br />

correlation and ANOVA.<br />

Group 1<br />

Mean IBL 330 µg·yr/dL<br />

Maximum blood Pb 40 µg/dL<br />

TWA 29 µg/dL<br />

Tibial Pb 20 µg/g<br />

Calcaneal Pb 79 µg/g<br />

Group 2<br />

Mean IBL 823 µg·yr/dL<br />

Maximum blood Pb 69 µg/dL<br />

TWA 40 µg/dL<br />

Tibial Pb 35 µg/g<br />

Calcaneal Pb 100 µg/g<br />

IBL, TWA and maximum<br />

blood Pb were also calculated<br />

<strong>for</strong> the previous 3 yrs with a<br />

median TWA3 <strong>of</strong> 29 µg/dL<br />

Pb workers<br />

Mean (SD) blood Pb 28<br />

(11) µg/dL<br />

Mean (SD) IBL 410<br />

(360.8) µg·yr/dL<br />

Mean (SD) TWA 32<br />

(14.1) µg/dL<br />

Mean (SD) yrs exposed<br />

11(8.1)<br />

Control<br />

Mean (SD) blood Pb 8<br />

4.5) µg/dL<br />

Partial correlations controlling <strong>for</strong> age, sex and education in group 1<br />

found block design, digit symbol, digit span, similarities, Santa Ana 1<br />

and memory <strong>for</strong> design significantly associated with recent measures<br />

<strong>of</strong> exposure and embedded figures with maximum blood Pb. In group<br />

2 embedded figures, digit symbol, block design, and associative<br />

learning were associated with IBL and /or maximum blood Pb.<br />

Calcaneal Pb was weakly associated with digit symbol, digit symbol<br />

retention, and synonyms. There was no association with tibial Pb in<br />

either group. Group 1 divided at the median TWA3 <strong>of</strong> 29 µg/dL<br />

found the high group had lower scores <strong>for</strong> visuospatial and<br />

visuoperceptive tasks (digit symbol, embedded figures and memory<br />

<strong>for</strong> design). Overall past high exposure, blood Pb >50 µg/dL, had the<br />

greatest effect on tests requiring the encoding <strong>of</strong> complex visually<br />

presented stimuli. The authors conclude that the effect <strong>of</strong> Pb on brain<br />

function is better reflected by history <strong>of</strong> blood Pb than content <strong>of</strong> Pb<br />

in bone.<br />

No association with neuropsychological tests (addition, digit span,<br />

finger tapping symbol digit and motor test from Luria) and blood Pb,<br />

TWA or IBL were found. Blood Pb and visual contrast sensitivities at<br />

the high frequencies were significantly associated <strong>for</strong> the entire group.<br />

Blood Pb and serum prolactin in the whole group was significantly<br />

associated. Increased prolactin secretion occurs with a variety <strong>of</strong><br />

neurotoxins and reflects impaired dopamine function in the pituitary.<br />

The estimated threshold <strong>for</strong> a significant increase <strong>of</strong> high prolactin<br />

levels was at a blood Pb <strong>of</strong> 10 µg/dL.


AX6-41<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

_sterberg et al. (1997)<br />

Sweden<br />

38 workers, median age 42 (no range) yrs at<br />

a secondary smelter stratified by finger bone<br />

Pb concentration and along with 19 controls<br />

matched triplets <strong>for</strong> age, education and job<br />

level. Median yrs employed 10 (2-35).<br />

High bone Pb<br />

Median (range) bone 32<br />

(17-101) µg/g<br />

Median (range) blood Pb<br />

38 (19-50) µg/dL<br />

Median (range) peak blood<br />

Pb 63 (46-90) µg/dL<br />

Median (range) IBL 408<br />

(129-1659) µg·yr/dL<br />

Low bone Pb<br />

Median (range) bone 16<br />

(!7 to 49) µg/g<br />

Median (range) blood Pb<br />

34 (17-55) µg/dL<br />

Median (range) peak blood<br />

Pb 57 (34-78) µg/dL<br />

Median (range) IBL 250<br />

(47-835) µg·yr/dL<br />

Controls<br />

Median (range) bone 4<br />

(!19 to 18) µg/g<br />

Median (range) blood Pb 4<br />

(1-7) µg/dL<br />

A cognitive test battery (36 tests) covering learning and memory,<br />

visuomotor function, visuospatial function, concentration and<br />

sustained attention found no impairment or dose-response<br />

relationships with any <strong>of</strong> the markers <strong>of</strong> Pb exposure. Deviating test<br />

scores (belong to 10% lowest reference norms) were less in high<br />

bone Pb (1 vs. 4 vs. 4). None <strong>of</strong> the deviating parameters were<br />

significantly correlated with any <strong>of</strong> the Pb indices. Even when age<br />

was taken into account the significant associations between outcome<br />

and Pb exposure metrics did not exceed chance in light <strong>of</strong> the<br />

numerous analyses per<strong>for</strong>med. These were the most heavily Pbexposed<br />

workers in Sweden. It was unusual that the 2 visuomotor<br />

tasks significantly different had better per<strong>for</strong>mance in the Pbexposed<br />

workers compared to the controls.


AX6-42<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Stollery et al. (1991)<br />

England<br />

Stollery (1996)<br />

England<br />

Barth et al. (2002)<br />

Austria<br />

Seventy Pb-exposed workers, mean age<br />

41(no SD) yrs, grouped by blood Pb<br />

(40 µg/dL had impairments that correlated best with avg blood Pb<br />

over the preceding 8 mos. Workers with blood Pb between 21 to<br />

40 µg/dL had essentially no impairment.<br />

Same as above Movement and decision slowing was correlated with blood Pb.<br />

Slowed movement time was constant across response-stimulus<br />

intervals in contrast to decision time that was increasingly affected by<br />

Pb especially at the shortest response-stimulus intervals.<br />

This supported the finding that decision gaps, central in origin, as<br />

opposed to movement gaps are selectively affected by Pb exposure in<br />

this population.<br />

Pb workers<br />

Mean (SD) blood Pb 31<br />

(11.2) µg/dL<br />

Mean (SD) IBL 384<br />

(349.0) µg·yr/dL<br />

Mean (SD) yrs employed<br />

12 (9.0)<br />

Controls<br />

Mean (SD) blood Pb 4<br />

(2.0) µg/dL<br />

Significant differences were found <strong>for</strong> block design (p # 0.01), visual<br />

recognition (p # 0.01) and Wisconsin card sorting (categories<br />

p = 0.0005, total errors p = 0.0025, perseverations p = 0.001, loss <strong>of</strong><br />

sorting principle p = 0.003) but not SRT or digit symbol. In the<br />

exposed group partial correlation adjusting <strong>for</strong> age found no<br />

significant associations with IBL (n = 53). In the entire group the full<br />

correlation was significant <strong>for</strong> blood Pb and Wisconsin card sorting,<br />

block design and visual recognition (n = 100). Visuospatial abilities<br />

and executive function were better predicted by blood Pb than<br />

cumulative Pb exposure. It is unusual that a frontal lobe task is<br />

associated with blood Pb when SRT and digit symbol sensitive to the<br />

affects <strong>of</strong> Pb are not.


AX6-43<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Winker et al. (2005)<br />

Austria<br />

Winker et al. (2006)<br />

Austria<br />

48 workers <strong>for</strong>merly Pb-exposed, mean<br />

duration since last exposure 5 (3.5) yrs, and<br />

mean age 40 (8.8) yrs were matched with 48<br />

controls <strong>for</strong> age, verbal intelligence, yrs <strong>of</strong><br />

education and number <strong>of</strong> alcoholic drinks.<br />

Group differences and dose-response<br />

relationship were explored.<br />

The same 48 workers <strong>for</strong>merly Pb-exposed<br />

described above were compared to the<br />

47 exposed workers described by Barth et al.<br />

(2002). Both groups were comparable <strong>for</strong><br />

age and verbal intelligence. Group<br />

differences and differences by duration <strong>of</strong><br />

exposure and exposure absence were<br />

evaluated.<br />

Formerly Pb-exposed<br />

Mean (SD, range) blood Pb<br />

5.4 (2.7, 1.6-14.5) µg/dL<br />

Mean (SD) IBL 4153.3<br />

(36930.3) µg·yr/dL<br />

Controls<br />

Mean (SD, range) blood Pb<br />

4.7 (2.5, 1.6-12.6) µg/dL<br />

Exposed workers<br />

Mean (SD, range) blood Pb<br />

31 (11.2, 10.6-62.1) µg/dL<br />

Mean (SD) IBL 4613<br />

(4187.6) µg·yr/dL<br />

Formerly Pb-exposed<br />

Mean (SD, range) blood Pb<br />

5.4 (2.7, 1.6-14.5) µg/dL<br />

Mean (SD) IBL 4153.3<br />

(36930.3) µg·yr/dL<br />

No significant differences on neurobehavioral battery were present<br />

when groups compared by t-tests <strong>for</strong> paired samples. When the<br />

groups were combined, partial correlation adjusting <strong>for</strong> age found<br />

significant negative correlation between blood Pb and Block Design,<br />

(r = −0.28, p < 0.01) Visual Recognition (r = −0.21, p < 0.05) and<br />

Digit Symbol Substitution (r = −0.26, p < 0.01). The authors<br />

conclude that the cognitive deficits associated with low-level Pb<br />

exposure are reversible. However there appears to be a residual effect<br />

primarily from those with the highest past Pb exposure.<br />

Mann-Whitney test found significantly better per<strong>for</strong>mance in the<br />

<strong>for</strong>merly Pb-exposed workers <strong>for</strong> Block Design (p = 0.005) and<br />

Wisconsin Card Sorting Test (categories p = 0.0005, total errors<br />

p = 0.005, perseverations p = 0.0095 and loss <strong>of</strong> sorting principle<br />

p = 0.02). To further examine the reduction <strong>of</strong> cognitive impairment<br />

with absence <strong>of</strong> exposure, workers were stratified by duration <strong>of</strong><br />

exposure and exposure absence – short exposure and long absence;<br />

long exposure and long absence; short exposure and short/no absence<br />

and long exposure and short/no absence. Linear contrasts <strong>for</strong> Block<br />

Design (p = 0.003) and Wisconsin Card Sorting Test (categoriesp<br />

< 0.001, total errors p = 0.001, perseverations p = 0.019 and loss <strong>of</strong><br />

sorting principle p = 0.030) were highly significant in the<br />

hypothesized direction. Results were believed to support reversibility<br />

<strong>of</strong> cognitive deficits related to occupational Pb exposure.


AX6-44<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Maizlish et al. (1995)<br />

Venezuela<br />

Asia<br />

Schwartz et al.<br />

(2001a)<br />

South Korea<br />

43 workers from a Pb smelter, mean age 34<br />

(9) yrs and 47 nonexposed workers, mean<br />

age 35 (11) yrs completed the WHO<br />

neurobehavioral core test battery. ANCOVA<br />

and linear regression adjusting <strong>for</strong> potential<br />

confounders examined relationship <strong>of</strong> Pb<br />

exposure and NCTB.<br />

803 Korean Pb-exposed workers, 80% men<br />

and 20% women, mean age 40 (10.1) yrs<br />

from a variety <strong>of</strong> industries, and 135<br />

controls, 92% men and 8% women, mean<br />

age 35 (9.1) yrs. Educational levels Pbexposed<br />

workers/controls<br />

#6 yrs = 23% / 7%, 7-9 yrs 23% / 11%, 10-<br />

12 yrs = 46% / 70%, and >12 yrs 8% / 12%.<br />

Group differences on neurobehavioral testing<br />

after controlling <strong>for</strong> covariates and linear<br />

regression controlling <strong>for</strong> covariates<br />

examined the presence <strong>of</strong> a dose-effect<br />

relationship.<br />

Pb workers<br />

Mean (SD) blood Pb 43<br />

(12.1) µg/dL<br />

Mean (SD) peak blood Pb<br />

60 (20.3) µg/dL<br />

Mean (SD) TWA 48<br />

(12.1) µg/dL<br />

Controls<br />

Mean (SD) blood Pb 15<br />

(6) µg/dL<br />

Mean (SD) peak blood Pb<br />

15 (6) µg/dL<br />

Mean TWA 15 (6) µg/dL<br />

Pb workers<br />

Mean (SD) blood Pb 32<br />

(15) µg/dL<br />

Mean (SD) tibia bone Pb<br />

37 (40.3) µg/g<br />

Mean (SD) DMSAchelatable<br />

Pb level 186<br />

(208.1) µg<br />

Controls<br />

Mean (SD) blood Pb 5<br />

(1.8) µg/dL<br />

Mean (SD) Tibia bone Pb 6<br />

(7) µg/g<br />

Group comparison was significant <strong>for</strong> SRT (p = 0.06) but the Pb<br />

exposed workers per<strong>for</strong>med faster. Linear regression found SRT<br />

poorer per<strong>for</strong>mance with blood Pb and TWA but not significant.<br />

With peak blood Pb SRT improved with increasing Pb exposure.<br />

In this study only symptoms were significantly different between<br />

the groups.<br />

Nineteen outcomes examined. Compared to controls Pb exposed<br />

workers per<strong>for</strong>med significantly worse on SRT, Digit Span, Benton<br />

Visual Retention, Colored Progressive Matrices, Digit Symbol, and<br />

Purdue Pegboard after controlling <strong>for</strong> age, gender and education. The<br />

association <strong>of</strong> DMSA with test per<strong>for</strong>mance was lost by the addition<br />

<strong>of</strong> blood Pb. Bone Pb was not associated with neurobehavioral<br />

per<strong>for</strong>mance. Blood Pb was the best predictor <strong>for</strong> significant<br />

decrements in neurobehavioral per<strong>for</strong>mance on trails B (∃ = !0.0025<br />

[SE 0.0009], p < 0.01), Purdue Pegboard (dominant ∃ = !0.0159 [SE<br />

0.0042], p < 0.01; non-dominant ∃ = 0.0169 [SE 0.0042], p < 0.01;<br />

both ∃ = !0.0142 [SE 0.0038], p < 0.01; assembly ∃ = !0.0493 [SE<br />

0.0151], p < 0.01), and Pursuit Aiming (# correct ∃ = !0.1629 [SE<br />

0.0473], p < 0.01; # incorrect ∃ = !0.0046 [SE 0.0023], p < 0.05). The<br />

magnitude <strong>of</strong> the effect <strong>for</strong> these eight tests significantly associated<br />

with blood Pb was an increase in blood Pb <strong>of</strong> 5 µg/dL was equivalent<br />

to an increase <strong>of</strong> 1.05 yrs in age. Use <strong>of</strong> Lowess lines <strong>for</strong> Purdue<br />

Pegboard (assembly) and Trails B suggested a threshold at blood Pb<br />

18 µg/dL after which there is a decline <strong>of</strong> per<strong>for</strong>mance.


AX6-45<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Schwartz et al. (2005)<br />

South Korea<br />

1997-2001<br />

Longitudinal decline in neurobehavioral<br />

per<strong>for</strong>mance examined in 576 <strong>of</strong> the above<br />

group <strong>of</strong> Pb exposed workers who completed<br />

3 visits at one yr intervals.<br />

Mean age at baseline was 41 (9.5) yrs and<br />

job duration 9 (6.3) yrs and 76% were men.<br />

Compared to non-completers Pb workers<br />

who completed 3 visits were 3.3 yrs older,<br />

baseline mean blood Pb was 2.0µg/dL lower,<br />

on the job 1.6 yrs longer, 24% women vs.<br />

10% <strong>of</strong> noncompleters, and usually had less<br />

than high school education. Models<br />

examined short-term vs. long-term effects.<br />

Final model had current blood Pb, tibia bone<br />

Pb and longitudinal blood Pb and covariates.<br />

Baseline mean (SD) blood<br />

Pb 31 (14.2) µg/dL<br />

Mean (SD) tibia<br />

Pb 38 (43) µg/g<br />

Blood Pb from baseline correlated with those from visit 2 and 3 and<br />

baseline tibial Pb correlated with that measured at visit 2. Crosssectional<br />

associations <strong>of</strong> blood Pb or short-term change occurred with<br />

Trails A (∃ = !0.0020 [95% CI: !0.0040, !0.0001]) and B<br />

(∃ = !0.0037 [95% CI: !0.0057, !0.0017]), Digit Symbol (∃ = !0.0697<br />

[95% CI: !0.1375, !0.0019]) , Purdue Pegboard<br />

(dominant ∃ = !0.0131 [95% CI: !0.0231, !0.0031]; non-dominant<br />

∃ = !0.0161 (95% CI: !0.0267, !0.0055); both (∃ = !0.0163, [95% CI:<br />

!0.0259, !0.0067]; assembly (∃ = !0.0536 [95% CI: !0.0897,<br />

!0.0175]), and Pursuit Aiming (# correct ∃ = 0.1526, [95% CI:<br />

!0.2631, !0.0421]) after covariates. However, longitudinal blood Pb<br />

was only associated with poorer per<strong>for</strong>mance on Purdue Pegboard<br />

(non-dominant ∃ = !0.0086 [95% CI: !0.0157, !0.0015]; both<br />

(∃ = !0.0063 [95% CI: !0.0122, 0.0004]; assembly (∃ = !0.0289 [95%<br />

CI: !0.0532, !0.0046]). Historical tibial bone Pb was associated with<br />

digit symbol (∃ = !0.0067 [95% CI: !0.0120, 0.0014]) and Purdue<br />

Pegboard (dominant ∃ = !0.0012, [95% CI: !0.0024, !0.0001]).<br />

Magnitude <strong>of</strong> Pb associations was expressed as the number <strong>of</strong> yrs <strong>of</strong><br />

increased age at baseline that was equivalent to an increase <strong>of</strong> Pb from<br />

the 25th to 75th percentile. At baseline, these Pb associations were<br />

equivalent to 3.8 yrs <strong>of</strong> age <strong>for</strong> cross-sectional blood Pb, 0.9 yrs <strong>of</strong><br />

age <strong>for</strong> historical tibial Pb and 4.8 yrs <strong>of</strong> age <strong>for</strong> longitudinal blood<br />

Pb. Analyses showed decline in per<strong>for</strong>mance over time related to<br />

tibia Pb.


AX6-46<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Hwang et al. (2002)<br />

South Korea<br />

Chuang et al. (2005)<br />

Taiwan<br />

From the above cohort <strong>of</strong> 803 Korean Pb<br />

workers, 212 consecutively enrolled workers,<br />

were examined <strong>for</strong> protein kinase C (PKC)<br />

activity and the relations between blood Pb<br />

and neurobehavioral per<strong>for</strong>mance. PKC<br />

activity assessed by measuring levels <strong>of</strong><br />

phosphorylation <strong>of</strong> three erythrocyte<br />

membrane proteins. Seventy-four percent <strong>of</strong><br />

workers were men, mean age 36(0.8)yrs,<br />

duration <strong>of</strong> exposure 9 (0.6) and education<br />

93% had high school or less. For the female<br />

workers, mean age 47 (0.9) yrs, duration <strong>of</strong><br />

exposure 6 (0.5), and education 95% had<br />

high school or less.<br />

27 workers from a glazing factory were<br />

administered a computerized<br />

neurobehavioral battery 3 times over 4 yrs.<br />

At yr 1, the mean age was 40 (9.6) yrs. In<br />

the first yr workers were compared to a<br />

referent group matched <strong>for</strong> age and<br />

education. Neurobehavioral per<strong>for</strong>mance<br />

compared in first yr to referent group with<br />

adjustment <strong>for</strong> age and Vocabulary.<br />

Generalized mixed linear mixed models<br />

analyzed relationship between blood Pb level<br />

and neurobehavioral test per<strong>for</strong>mance after<br />

adjusting <strong>for</strong> age and Vocabulary.<br />

Male workers<br />

Mean (SD) blood Pb 32<br />

(13.0) µg/dL<br />

Mean (SD) tibia Pb 38<br />

(39.6) µg/g<br />

Mean (SD) ZPP 69<br />

(47.8) µg/dL<br />

Female workers<br />

Mean (SD) blood Pb 20<br />

(9.2) µg/dL<br />

Mean (SD) tibia Pb 26<br />

(14.7) µg/g<br />

Mean (SD) ZPP 72<br />

(29.7) µg/dL<br />

Pb workers<br />

Yr 1<br />

Mean (SD) blood Pb 26<br />

(12)<br />

Yr 3<br />

Mean (SD) blood Pb 11<br />

(6.4)<br />

Yr 4<br />

Mean (SD) blood Pb 8 (6.9)<br />

Referent<br />

Mean (SD) blood Pb 7 (4.2)<br />

Blood Pb was associated significantly with decrements in Trails B<br />

(∃ = !0.003 [SE 0.002], p < 0.10), SRT (∃ = !0.0005 [SE 0.0003],<br />

p < 0.10) and Purdue Pegboard (dominant ∃ = !0.21 [SE 0.010],<br />

p < 0.05); non-dominant (∃ = !0.021 [SE 0.010], p < 0.05); both<br />

(∃ = !0.021 [SE 0.009], p < 0.05). PKC activity as measured by backphosphorylation<br />

<strong>of</strong> erythrocyte membrane proteins was not associated<br />

with neurobehavioral test scores. Addition <strong>of</strong> the interaction term <strong>of</strong><br />

blood Pb by back-phosphorylation dichotomized at the median found<br />

significant effect modification with the association <strong>of</strong> higher blood Pb<br />

and poorer neurobehavioral per<strong>for</strong>mance occurring only among<br />

workers with lower back-phosphorylation levels that corresponds to<br />

higher in vivo PKC activity. Association <strong>of</strong> blood Pb and SRT <strong>for</strong> the<br />

52 kDa subunit with high in vivo PKC activity (adjusted ∃ = !0.001,<br />

p < 0.01) and <strong>for</strong> low in vivo PKC (adjusted ∃ = !0.0001, p = 0.92).<br />

The authors suggest that PKC activity may identify a subpopulation at<br />

increase risk <strong>of</strong> neurobehavioral effects <strong>of</strong> Pb.<br />

Referents scored significantly lower on questionnaire <strong>for</strong> chronic<br />

symptoms in yr 1. In the mixed model analyses finger tapping<br />

dominant (p = 0.008) and non-dominant (p = 0.025) were<br />

significantly inversely associated with blood Pb. Pattern comparison<br />

(p < 0.001) and Pattern memory (p = 0.06) improved significantly as<br />

blood Pb levels improved. Chronic symptoms and neurobehavioral<br />

per<strong>for</strong>mance appear to reverse when Pb exposure is decreased.<br />

However since the referent group was not tested in yr 3 and yr 4 it<br />

was not possible to control <strong>for</strong> practice effect known to occur with<br />

repeat neurobehavioral testing even at two yr intervals.


AX6-47<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Tsai et al. (2000)<br />

Taiwan<br />

Chia et al. (2004)<br />

Singapore<br />

Chia et al. (1997)<br />

Singapore<br />

19 Pb workers and 19 referents included in<br />

the above publication, mean age 39 yrs in<br />

both groups and mean education 10 (2.9) and<br />

9 (3.2) yrs, respectively, were tested with a<br />

computerized neurobehavioral battery.<br />

Alcohol use was similar. Mean duration <strong>of</strong><br />

Pb exposure 6 (2.5) yrs. Student’s t<br />

compared neurobehavioral per<strong>for</strong>mance<br />

between the two groups.<br />

120 workers from Pb stabilizer factories,<br />

mean age 40 (10.7) yrs, duration <strong>of</strong> exposure<br />

10.2 (7.9) were given a neurobehavioral<br />

battery. Genotyping <strong>of</strong> ALAD<br />

polymorphisms was per<strong>for</strong>med. ANCOVA<br />

used to test <strong>for</strong> differences in<br />

neurobehavioral per<strong>for</strong>mance among ALAD<br />

polymorphism types adjusting <strong>for</strong> age,<br />

exposure duration and blood Pb.<br />

50 Pb battery manufacturing workers, mean<br />

age 36 (10.6) yrs, education 8.6 (2.1) yrs<br />

duration <strong>of</strong> employment 9 (7.4) yrs and<br />

97 controls, mean age 34 (3.7) yrs, and<br />

education 12 (1.8) yrs were administered a<br />

neurobehavioral battery. ANCOVA and<br />

linear regression used to assess relationship<br />

<strong>of</strong> Pb dose and per<strong>for</strong>mance.<br />

Mean (SD) blood Pb 32<br />

(12.2) µg/dL<br />

Referent<br />

Mean (SD) blood Pb 7<br />

(2.7) µg/dL<br />

Mean (SD) blood Pb 22<br />

(9.4) µg/dL<br />

Mean (SD) ALAD0.6<br />

(0.25) µm <strong>of</strong><br />

porphobilinogen/h/ml <strong>of</strong><br />

RBC<br />

Mean (SD) ALAU0.9<br />

(0.56) mg/g creatinine<br />

Pb workers<br />

Median (range) blood Pb <strong>of</strong><br />

38 (13.2-64.6) µg/dL<br />

Median (range) IBL 264<br />

(10.0-1146.2) µg·yr/dL<br />

Controls<br />

Median (range) blood Pb 6<br />

(2.4-12.4) µg/dL<br />

Poorer per<strong>for</strong>mance in Pb workers <strong>for</strong> finger tapping, dominant and<br />

non-dominant, and continuous per<strong>for</strong>mance task but only finger<br />

tapping was significant. Pb workers per<strong>for</strong>med better than referents<br />

on Associate Learning, Pattern Comparison Test, Pattern Memory<br />

Test, Visual Delay and Associate Learning Delayed that was<br />

attributed to higher mean education.<br />

Frequency <strong>of</strong> ALAD11, 87%, ALAD12, 12%, and ALAD22, 1%.<br />

Mean blood Pb adjusting <strong>for</strong> age and exposure duration was 20 µg/dL<br />

<strong>for</strong> ALAD11 (n = 107) and 20.4 µg/dL <strong>for</strong> ALAD12 and 22 (n = 13).<br />

However ALAU was significantly higher in ALAD11 (p = 0.023).<br />

After adjusting <strong>for</strong> the covariates significant differences <strong>for</strong> grooved<br />

pegboard dominant hand (p = 0.01), non-dominant hand (p = 0.04),<br />

and grooved pegboard mean time (p = 0.006) were found between<br />

ALAD11 and ALAD12 and 22. Considering cognitive tests were part<br />

<strong>of</strong> battery it is surprising education was ignored. As noted by the<br />

authors the study only had 13 in the group with better per<strong>for</strong>mance<br />

and the ALAD12 or 22 genotypes limiting the power.<br />

Significant group differences <strong>for</strong> Santa Ana, grooved pegboard, digit<br />

symbol, pursuit aiming and Trails A and B after adjusting <strong>for</strong> age,<br />

education, smoking, ethnic group and alcohol use. When the exposed<br />

group was stratified by age, in the group >35 yrs the poorer<br />

per<strong>for</strong>mance on digit symbol and Trails A was significantly<br />

associated with cumulative Pb and not blood Pb after adjusting<br />

<strong>for</strong> age and education.


AX6-48<br />

Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Niu et al. (2000)<br />

China<br />

Boey and Jeyaratnam<br />

(1988)<br />

Singapore<br />

44 Pb-exposed workers (17 men, 27 women)<br />

from Pb printing houses, mean age 35 (4.9)<br />

and education 9.3 (no SD) yrs and 34<br />

controls (19 men and 15 women), mean age<br />

33 (7.4) yrs and education 9.5 (no SD) yrs<br />

completed the NCTB. ANCOVA controlling<br />

<strong>for</strong> age, sex and education examined group<br />

differences and linear regression <strong>for</strong> doseresponse<br />

relationship.<br />

49 Pb-exposed workers, mean age 26 (7.6)<br />

yrs and 36 controls, mean age 30 (6.4) yrs<br />

completed SRT and 8 psychological tests<br />

covering attention, vigilance, visual-motor<br />

speed, short-term memory, visuomotor<br />

tracking, visual scanning, and manual<br />

dexterity. Control group was matched <strong>for</strong><br />

education level. Discriminate analysis <strong>of</strong><br />

neurobehavioral tests per<strong>for</strong>med to determine<br />

which best discriminate the groups.<br />

Pb workers<br />

Mean (SD) blood Pb 29<br />

(26.5) µg/dL<br />

(8 workers blood Pb<br />

exceeded 50 µg/dL)<br />

Controls<br />

Mean (SD) blood Pb 13<br />

(9.9) µg/dL<br />

(1 control blood Pb<br />

exceeded 50 µg/dL)<br />

Pb workers<br />

Mean (SD) blood Pb 49<br />

(15) µg/dL<br />

Controls<br />

Mean (SD) blood Pb 15<br />

(3) µg/dL<br />

SRT (F = 2.30, p < 0.05), digit symbol (F = 4.81, p < 0.01) pursuit<br />

aiming # correct (F = 7.186, p < 0.01) and pursuit aiming total<br />

(F = 6.576, p < 0.01) had significantly poorer per<strong>for</strong>mance compared<br />

to controls. No repression analyses provided.<br />

Six tests were significantly different between the two groups-Digit<br />

Symbol, Bourdon-Wiersma, Trails A, Santa Ana dominant, Flicker<br />

Fusion and SRT. The group <strong>of</strong> tests that best differentiates Pbexposed<br />

workers from nonexposed workers were Simple Reaction<br />

Time, Digit Symbol (WAIS) and Trail Making Test (Part A) with<br />

long latency in reaction time contributing three times more to the<br />

derived function than Digit Symbol (WAIS) or Trails A.


AX6-49<br />

Table AX6-3.4. Meta-analyses <strong>of</strong> Neurobehavioral Effects with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Balbus-Kornfeld et al.<br />

(1995)<br />

Davis and Svendsgaard<br />

(1990)<br />

Meyer-Baron and<br />

Seeber (2000)<br />

Reviewed 21 studies from 28 publications;<br />

number <strong>of</strong> subjects ranged from 9-708.<br />

Meta-analysis <strong>of</strong> 32 studies <strong>of</strong> nerve<br />

conduction studies and Pb exposure.<br />

Meta-analysis <strong>of</strong> studies with blood Pb<br />


AX6-50<br />

Table AX6-3.4 (cont’d). Meta-analyses <strong>of</strong> Neurobehavioral Effects with Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Schwartz et al. (2002)<br />

Letter to the Editor commenting on<br />

shortcomings in the Goodman et al. (2002)<br />

meta-analysis on studies <strong>of</strong> neurobehavioral<br />

testing in workers occupationally exposed to<br />

Pb.<br />

Seeber et al. (2002) A comparison <strong>of</strong> the two meta-analyses<br />

Meyer-Baron and Goodman) per<strong>for</strong>med to<br />

evaluate recommendations <strong>of</strong> a German BEI<br />

<strong>of</strong> 40 µg/dL.<br />

Graves et al. (1991) A meta-analysis on 11 case-control studies <strong>of</strong><br />

Alzheimer’s disease <strong>for</strong> occupational<br />

exposure to solvents and Pb.<br />

The six points regarding problems with the methodology included:<br />

(1) no evaluation <strong>of</strong> quality <strong>of</strong> study design or statistical methods,<br />

(2) data from poorly done and well done studies are combined,<br />

(3) included 6 studies with no age adjustment and 3 with no<br />

adjustment <strong>for</strong> education, (4) confounding <strong>of</strong> age and education<br />

when addressed the variation across studies not discussed, (5) main<br />

effect only examined exposed vs. nonexposed comparisons that are<br />

known to have the lowest power, cannot evaluated dose-effect<br />

relationships and have a tendency <strong>for</strong> selection bias, and (6) few <strong>of</strong><br />

the 22 studies included contributed to effect size.<br />

Effect size calculated <strong>for</strong> 12 tests in two meta-analyses and 10 tests<br />

from one meta-analyses found subtle impairments associated with<br />

blood Pb between37 µg/dL and 52 µg/dL <strong>for</strong> Logical Memory,<br />

Visual Reproduction, Simple Reaction Time, Attention Test d2,<br />

Block Design, and Picture Completion, Santa Ana, Grooved<br />

Pegboard and Eye-hand Coordination. Effect sizes related to age<br />

norms between ~40 to 50 yrs. For example, !3 score on Block<br />

Design = 10 to 15 yrs; !3.5 score on Digit Symbol = 10 yrs; !21 score<br />

on Cancellation d2 = 10 yrs; and +5 to +6 on Trails A = 10 to 20 yrs.<br />

This analyses concluded that both meta-analyses supported<br />

recommendation <strong>for</strong> German BEI <strong>of</strong> 40 µg/dL.<br />

Four studies had data <strong>for</strong> Pb exposure with a pooled analysis <strong>of</strong><br />

relative risks <strong>for</strong> occupational Pb <strong>of</strong> 0.71 (95% CI: 0.36, 1.41).<br />

The exposure frequencies were 16/261 <strong>for</strong> the cases and 28/337 <strong>for</strong><br />

the controls.


AX6-51<br />

Table AX6-3.5. Neurophysiological Function and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada<br />

Bleecker et al. (2005b)<br />

New Brunswick<br />

1992-1993<br />

Europe<br />

Kovala et al. (1997)<br />

Finland<br />

74 current smelter workers, mean age<br />

44 (8.4) yrs, education 8 (2.8) yrs and<br />

employment duration 20 (5.3) yr had current<br />

perception threshold (CPT) measured <strong>for</strong><br />

large and small myelinated and unmyelinated<br />

nerve fibers in the finger. Linear regression<br />

modeled CPT on metrics <strong>of</strong> Pb dose after<br />

adjusting <strong>for</strong> covariates. Interaction <strong>of</strong> Pb<br />

dose and ergonomic stressor on peripheral<br />

nerve function was assessed.<br />

60 workers in a Pb battery factory with a<br />

mean age <strong>of</strong> 43 (9) yrs and mean exposure<br />

duration <strong>of</strong> 16 (8) yrs. Nerve conduction<br />

studies, vibration thresholds, and quantitative<br />

EEG were per<strong>for</strong>med. Relationship <strong>of</strong> Pb<br />

exposure with peripheral nerve function and<br />

quantitative EEG were examined by partial<br />

correlation and regression analyses adjusting<br />

<strong>for</strong> age.<br />

Mean (SD) blood Pb 26<br />

(7.1) µg/dL<br />

Mean (SD) IBL 891<br />

(298.8)<br />

µg·yr/dL<br />

Mean (SD) TWA 42<br />

(8.4)µg/dL<br />

Mean (SD) tibia bone 40<br />

(23.8) µg/g<br />

5 metrics relating to IBL<br />

cumulated only exposure<br />

above increasing blood Pb<br />

ranging from 20 to<br />

60 µg/dL<br />

Mean (SD) tibial Pb 26<br />

(17) mg/kg<br />

Mean (SD) calcaneal Pb<br />

88 (54) mg/kg<br />

Mean (SD) IBL 546<br />

(399)<br />

µg·yr/dL<br />

Mean (SD) TWA 34<br />

(8.4) µg/dL<br />

Mean (SD) maximum<br />

blood Pb 53 (19) µg/dL,<br />

Mean (SD) blood Pb 27<br />

(8.4) µg/dL<br />

Blood Pb and tibial bone Pb were not associated with any <strong>of</strong> the three<br />

nerve fiber populations. IBL and TWA accounted <strong>for</strong> a significant<br />

percentage <strong>of</strong> the variance only <strong>for</strong> the large myelinated nerve fibers<br />

(♠R 2 = 3.9%, ♠R 2 = 8.7% respectively). The relationship <strong>of</strong> CPT and<br />

TWA was curvilinear with a minimum at a TWA <strong>of</strong> 28 µg/dL.<br />

Unique variance <strong>of</strong> CPT <strong>for</strong> large myelinated fibers explained by<br />

different thresholds <strong>of</strong> IBL were IBL – 3.9%, p = 0.08; IBL20 – 5.8%,<br />

p < 0.03, IBL30 – 7.8%, p < 0.02; IBL40, p < 0.005; IBL50,<br />

p < 0.005; and IBL60, p < 0.005. IBL60 also explained significant<br />

variance <strong>of</strong> CPT <strong>for</strong> small myelinated nerve fibers demonstrating an<br />

increased impairment in peripheral nerve function. This effect on<br />

myelinated sensory nerve fibers was enhanced when a measure <strong>of</strong><br />

ergonomic stress was added to the model <strong>for</strong> IBL60.<br />

The sensory amplitude <strong>of</strong> the median and sural nerves had a negative<br />

correlation with IBL and duration <strong>of</strong> exposure that was not related to<br />

age. Vibration threshold at the ankle related significantly to IBL and<br />

duration <strong>of</strong> exposure after adjusting <strong>for</strong> age. Vibration threshold in<br />

the finger was associated with blood Pb and blood Pb avgs over the<br />

past three yrs. The alpha and beta frequencies were more present in<br />

workers with higher long term Pb exposure such as tibial and<br />

calcaneal, IBL and TWA. Overall historical blood Pb measures were<br />

more closely associated with peripheral nerve function than bone Pb<br />

concentrations. The study had no comparison group and did not<br />

account <strong>for</strong> the effect <strong>of</strong> smoking and alcohol use or give their usage<br />

in this population.


AX6-52<br />

Table AX6-3.5 (cont’d). Neurophysiological Function and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia<br />

Schwartz et al.<br />

(2001a)<br />

South Korea<br />

1997-1999<br />

Schwartz et al. (2005)<br />

South Korea<br />

1997-2001<br />

804 workers from 26 different Pb using<br />

facilities and 135 controls with a mean age <strong>of</strong><br />

40 ( 10.1) and 35 (9.1) yrs respectively, job<br />

duration <strong>of</strong> 8 (6.5) and 9 (5.3) yrs<br />

respectively, and education level 42 % and<br />

69% completed high school respectively had<br />

comparable alcohol and smoking use. Linear<br />

regression used to compare vibration<br />

threshold in Pb exposed and controls<br />

controlling <strong>for</strong> potential confounders.<br />

Longitudinal decline in neurobehavioral<br />

per<strong>for</strong>mance examined in 576 <strong>of</strong> the above<br />

group <strong>of</strong> Pb exposed workers who completed<br />

3 visits at one yr intervals.<br />

Mean age at baseline was 41 (9.5) yrs and<br />

job duration 9 (6.3) yrs and 76% were men.<br />

Compared to non-completers Pb workers<br />

who completed 3 visits were 3.3 yrs older,<br />

baseline mean blood Pb was 2.0 µg/dL<br />

lower, on the job 1.6 yrs longer, 24% women<br />

vs. 10% <strong>of</strong> noncompleters, and usually had<br />

less than high school education. Models<br />

examined short-term vs. long-term effects.<br />

Final model had current blood Pb, tibia bone<br />

Pb and longitudinal blood Pb and covariates.<br />

Pb-exposed workers<br />

Mean (SD) blood Pb<br />

32 (15) µg/dL<br />

Mean (SD) tibia bone Pb<br />

37 (40.3) µg/g<br />

Mean (SD) DMSAchelatable<br />

Pb<br />

186 (208.1) µg (4 h<br />

collection)<br />

Baseline mean (SD) blood<br />

Pb 31 (14.2) µg/dL<br />

Mean (SD) tibia Pb 38<br />

(43) µg/g<br />

After adjustment <strong>for</strong> age, gender, education and height, tibia Pb but<br />

not blood Pb was significantly associated with poorer vibration<br />

threshold in the dominant great toe but not the finger (∃ = !0.0020<br />

[SE 0.0007], p < 0.01). These results contrast with those <strong>for</strong><br />

neurobehavioral measures (see above) per<strong>for</strong>med in the same study<br />

where tibial Pb was not a predictor <strong>of</strong> per<strong>for</strong>mance.<br />

After adjustment <strong>for</strong> age, visit number, education, gender, height<br />

(<strong>for</strong> vibration) and BMI (<strong>for</strong> grip strength and pinch) vibration<br />

threshold in the dominant great toe and not the finger was associated<br />

with tibia Pb (∃ = !0.0006 [95% CI: !0.0010, !0.0002]) and<br />

longitudinal blood Pb (∃ = !0.0051 [95% CI: !0.0078, !0.0024])<br />

in one model and blood Pb (∃ = !0.0019 [95% CI: !0.0039, 0.0001])<br />

in another model.


AX6-53<br />

Table AX6-3.5 (cont’d). Neurophysiological Function and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Chuang et al. (2000)<br />

Taiwan<br />

Chia et al. (1996a)<br />

Singapore<br />

206 Pb battery workers, mean age 41 yrs,<br />

with annual blood Pb <strong>for</strong> the previous five<br />

yrs had vibration perception measured in<br />

hand and foot. Relationship <strong>of</strong> Pb exposure<br />

term and vibration perception threshold<br />

assessed with multiple regressions, hockey<br />

stick regression analysis after adjusting <strong>for</strong><br />

potential confounders.<br />

72 workers in a Pb battery manufacturing<br />

factory with a mean age <strong>of</strong> 30 yrs and<br />

reference group <strong>of</strong> 82 workers had nerve<br />

conduction studies and blood Pb per<strong>for</strong>med<br />

every 6 mos over the course <strong>of</strong> three yrs.<br />

Only 28 Pb battery workers completed the<br />

program. At the end <strong>of</strong> the first yr <strong>of</strong> the 82<br />

workers in the comparison group only 26<br />

remained and by yr 3 this had decreased to 4.<br />

Mean nerve conduction values examined by<br />

ANCOVA between the exposed and<br />

reference after adjustment <strong>for</strong> age, ethnic<br />

group, smoking and drinking habits.<br />

Analysis <strong>of</strong> serial nerve conduction values<br />

and blood Pb treated as a clustered sample<br />

had the within-cluster regression coefficient<br />

examined. The 28 exposed workers were<br />

stratified by blood Pb level and the<br />

relationship between nerve conduction values<br />

and blood tested within the cluster.<br />

Mean blood Pb 28 µg/dL<br />

Mean blood Pb over past<br />

5 yrs 32 µg/dL<br />

Mean maximum blood Pb<br />

39 µg/dL<br />

Mean index <strong>of</strong> cumulative<br />

exposure 425 µg·yr/dL<br />

Mean TWA 32 µg/dL<br />

Mean working duration<br />

13 yrs and life span in<br />

work 31%<br />

Geometric mean blood Pb<br />

concentrations <strong>for</strong> the 6<br />

testing periods: 37, 41, 42,<br />

40, 41, and 37 µg/dL<br />

Overall range <strong>for</strong> blood Pb<br />

16-73 µg/dL<br />

After adjustment <strong>for</strong> age, sex, body height, smoking, alcohol<br />

consumption, and use <strong>of</strong> vibrating hand tools, significant association<br />

between mean blood Pb and mean TWA and vibration perception in<br />

the foot were found. After adjustment <strong>for</strong> the covariates, a hockey<br />

stick regression analysis <strong>of</strong> foot vibration threshold vs. mean blood<br />

Pb concentration <strong>for</strong> 5 yrs found an inflection point around 30 µg/dL<br />

with a positive linear relation above this point suggesting a potential<br />

threshold.<br />

The relationship between blood Pb levels and nerve conduction<br />

values <strong>for</strong> the 28 exposed workers was significant <strong>for</strong> all outcomes<br />

except median motor conduction velocity and ulnar sensory nerve<br />

conduction velocity and ulnar sensory amplitude. The regression<br />

correlation coefficients <strong>for</strong> blood Pb >40 µg/dL was significant <strong>for</strong><br />

all parameters except the median sensory conduction velocity and<br />

<strong>for</strong> blood Pb


AX6-54<br />

Table AX6-3.5 (cont’d). Neurophysiological Function and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Chia et al. (1996b)<br />

Singapore<br />

Chuang et al. (2004)<br />

Taiwan<br />

Yokoyama et al.<br />

(1998)<br />

Japan<br />

Extension <strong>of</strong> above study - 72 workers in Pb<br />

battery manufacturing and 82 controls. Mean<br />

duration <strong>of</strong> exposure 5.3 yrs.<br />

181 Pb battery manufacture workers were<br />

stratified by milk drinkers, n = 158 and nonor<br />

rare mild drinkers n = 23. Mean age in the<br />

two groups was 40 and 36 yrs and working<br />

duration 10/8 yrs respectively. Peripheral<br />

nerve evaluation was with current perception<br />

threshold at 3 frequencies 5Hz = C fibers,<br />

250 Hz = A-delta fibers and 2000 Hz = Abeta<br />

fibers. Linear regression estimated the<br />

association <strong>of</strong> CPT and Pb exposure variable<br />

and adjustment <strong>of</strong> milk intake and potential<br />

confounders.<br />

17 gun-metal workers, mean age 48 yrs and a<br />

20 controls with a mean age <strong>of</strong> 45 yrs had<br />

distribution <strong>of</strong> conduction velocities (DCV)<br />

measured and the maximum median sensory<br />

conduction velocity (SVC) per<strong>for</strong>med twice<br />

at a yr interval. Group differences<br />

controlling <strong>for</strong> confounders and dose-effect<br />

relationships were examined.<br />

Mean blood Pb 37 µg/dL<br />

Mean cumulative blood Pb<br />

137 µg·yr/dL<br />

Blood Pb<br />

Milk drinkers 25 µg/dL<br />

Non or rare milk drinkers<br />

30 µg/dL<br />

TWA<br />

Milk drinkers 28 µg/dL<br />

Non or rare milk drinkers<br />

32 µg/dL<br />

IBL<br />

Milk drinkers 316 µg·yr/dL<br />

Non or rare mild drinkers<br />

245 µg·yr/dL<br />

Mean blood Pb 40 µg/dL<br />

Mean mobilized Pb<br />

(CaEDTA) in urine<br />

1 mg/24 h<br />

ANCOVA found significant differences <strong>for</strong> all nerve conduction<br />

parameters except three <strong>for</strong> the ulnar nerve, after adjusting <strong>for</strong> age,<br />

ethnic groups, smoking and drinking habits. There was no<br />

significant correlation between blood Pb and cumulative blood Pb<br />

with nerve conduction values after linear regression with adjustment<br />

<strong>for</strong> confounders. When cumulative blood Pb was stratified- 12<br />

workers 300 µg·yr/dL ANCOVA found significant differences <strong>for</strong><br />

5 nerve conduction parameters. The strongest dose effect<br />

relationship was <strong>for</strong> sensory nerve conduction velocity.<br />

Age was significantly different but distributions <strong>of</strong> gender, smoking,<br />

alcohol use, use <strong>of</strong> hand vibration tool, working history and height<br />

were not different. Linear regressions found association <strong>of</strong> 5 Hz CPT<br />

and 250 Hz CPT in hand and foot with blood Pb and TWA but not<br />

IBL. However the protective effects <strong>of</strong> drinking milk was present <strong>for</strong><br />

all fiber populations only in the hands. This paper presents an<br />

unusual finding <strong>of</strong> subclinical Pb neuropathy involving the<br />

unmyelinated and small myelinated fibers. Toxic axonopathies<br />

classically involve the large nerve fibers. The main group difference<br />

may be related to other nutritional deficiencies associated with the<br />

malabsorption syndrome that lead to the non-milk drinking status.<br />

ANCOVA controlling <strong>for</strong> age and alcohol found mobilized Pb was<br />

associated with significant slowing in the large nerve fibers while<br />

blood Pb was not. Workers with increased change in mobilized Pb<br />

over 1 yr interval (mean 0.44 mg/24hr) had significant reduction in<br />

large fiber (V95) conduction velocity while those workers with less<br />

change in mobilized Pb (0.08 mg/24hr) did not have significant<br />

change in DCV or SVC. It appears that larger faster conducting<br />

nerve fibers are susceptible to Pb and a measure <strong>of</strong> body burden<br />

(readily mobilized Pb from s<strong>of</strong>t tissue) is a stronger predictor <strong>of</strong> this<br />

change than blood Pb.


AX6-55<br />

Table AX6-3.5 (cont’d). Neurophysiological Function and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

He et al. (1988)<br />

China<br />

Niu et al. (2000)<br />

China<br />

40 workers in a Pb smelter with age range 20<br />

to 45 yrs (no mean provided) and duration <strong>of</strong><br />

exposure 5.4 yrs. Fifty controls age 20 to<br />

55 yrs. Nerve conduction studies examined<br />

11 parameters. Student = s t-test examined<br />

<strong>for</strong> differences between exposed and<br />

controls.<br />

44 Pb-exposed workers (17 men, 27 women)<br />

from Pb printing houses, mean age 35 (4.9)<br />

and education 9.3 (no SD)yrs and 34 controls<br />

(19 men and 15 women), mean age 33 (7.4)<br />

yrs and education 9.5 (no SD) yrs had nerve<br />

conduction studies <strong>for</strong> maximal motor nerve<br />

conduction velocity. ANCOVA controlling<br />

<strong>for</strong> age, sex and education examined group<br />

differences and linear regression <strong>for</strong> doseresponse<br />

relationship.<br />

Mean blood Pb 40 µg/dL<br />

Mean urinary Pb 71 µg/dL<br />

Mean ALAU5 µg/dL<br />

Pb workers<br />

Mean blood Pb 29<br />

(26.5) µg/dL<br />

(8 workers blood Pb<br />

exceeded 50 µg/dL)<br />

Controls<br />

Mean blood Pb 13<br />

(9.9) µg/dL<br />

(1 control blood Pb<br />

exceeded 50 µg/dL)<br />

There were no symptoms or signs <strong>of</strong> peripheral nerve disorder.<br />

Both motor and sensory conduction velocities were slowed in the Pb<br />

exposed groups. 10 nerve conduction parameters were significant in<br />

the group with blood Pb >40 µg/dL and 6 parameters were<br />

significant in the group with blood Pb


AX6-56<br />

Table AX6-3.6. Evoked Potentials and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada<br />

Bleecker et al. (2003)<br />

New Brunswick<br />

1992-1993<br />

Europe<br />

Abbate et al. (1995)<br />

Italy<br />

Discalzi et al. (1992)<br />

Italy<br />

359 currently employed smelter workers, mean age 41<br />

yrs, had brainstem auditory evoked potentials (BAEP)<br />

measured. Relationship between absolute latencies<br />

and interpeak latencies assessed using linear regression<br />

after adjusting <strong>for</strong> potential confounders. Exposure<br />

was assessed in cases with clinical abnormalities in<br />

Wave I and I-V interpeak latency compared to those<br />

workers with normal BAEP using post-hoc analysis.<br />

300 Pb exposed men ages 30 to 40 yrs in good health<br />

with no other neurotoxic exposure had P100 latency<br />

measured <strong>for</strong> visual evoked potentials (VEP) <strong>for</strong> 15<br />

and 30 minute <strong>of</strong> arc. Groups created based upon<br />

blood Pb had VEPS examined followed by linear<br />

regression <strong>for</strong> each group.<br />

49 Pb exposed workers and 49 age and sex matched<br />

controls had BAEPs measured. Relationship <strong>of</strong> 6<br />

BAEP outcome variables and Pb exposure examined<br />

with analysis <strong>of</strong> variance and linear regression.<br />

Mean blood Pb 28 µg/dL<br />

Mean TWA 39 µg/dL<br />

Mean IBL 719 µg·yr/dL<br />

Blood Pb 17 to 60 µg/dL<br />

range<br />

Mean blood Pb <strong>for</strong> 4 groups<br />

n = 39 23 µg/dL<br />

n = 113 30 µg/dL<br />

n = 89 47 µg/dL<br />

n = 59 56 µg/dL<br />

Mean blood Pb 55 µg/dL<br />

Mean TWA <strong>for</strong> previous<br />

3 yrs 54 µg/dL<br />

Linear regression after the contribution <strong>of</strong> age found blood<br />

Pb and TWA were significantly associated with Wave I<br />

while IBL was significantly associated with Wave <strong>II</strong>I and I-<br />

<strong>II</strong>I interpeak interval. Four groups created with increasing<br />

abnormalities based upon clinical cut-<strong>of</strong>f scores <strong>for</strong> Wave I<br />

and I-V interpeak interval had similar age. blood Pb, TWA<br />

and IBL were all significantly higher in the group with<br />

prolonged Wave I and I-V interpeak interval compared<br />

to the group with normal BAEP = s. These findings<br />

support involvement <strong>of</strong> the brainstem and auditory nerve<br />

with Pb exposure.<br />

ANOVA <strong>of</strong> the blood Pb and P100 latencies were<br />

significantly prolonged <strong>for</strong> 15 and 30 minutes <strong>of</strong> arc.<br />

Linear regression found the association <strong>of</strong> blood Pb and<br />

P100 were significant in each group but the relationship<br />

was not proportional (angular coefficient). Effect <strong>of</strong> blood<br />

Pb on VEP began at 17-20 µg/dL. With age limited to one<br />

decade, contribution from age was not a concern. Even<br />

though no comparison group, careful screening ruled out<br />

other medical and eye conditions and other potential<br />

exposures.<br />

Latencies <strong>for</strong> waves I, <strong>II</strong>I, V and interpeak latencies, I-V, I-<br />

<strong>II</strong>I, and <strong>II</strong>I-V were all significantly prolonged in the Pbexposed<br />

workers (p < 0.04). No significant association<br />

found with linear regression between BAEP outcomes and<br />

exposure variables. In those workers with TWA<br />

>50 µg/dL, I-V latency was significantly prolonged<br />

compared to workers with TWA


AX6-57<br />

Table AX6-3.6 (cont’d). Evoked Potentials and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Discalzi et al. (1993)<br />

Italy<br />

Latin America<br />

Counter and Buchanan<br />

(2002)<br />

Ecuador<br />

Asia<br />

Holdstein et al. (1986)<br />

Israel<br />

22 battery storage workers, mean age 35 yrs and 22<br />

control group, age and sex matched, with normal<br />

hearing had BAEPs recorded. Latencies I and V and Pb<br />

exposure examined by ANOVA after stratifying blood<br />

Pb.<br />

30 Pb-glazing workers, median age 35 yrs, had puretone<br />

thresholds and BAEPs per<strong>for</strong>med. Regression<br />

analyses examined relations between auditory outcomes<br />

and blood Pb.<br />

20 adults and 8 children (mean age 27 yrs, range 8 - 56<br />

yrs) accidentally exposed to Pb through food until one yr<br />

prior to measurement <strong>of</strong> BAEP.<br />

Mean blood Pb 48µg/dL Interpeak latency I-V was significantly prolonged in Pb<br />

exposed workers (p = 0.001). No significant associations by<br />

linear regression between I-V and Pb exposure. Stratifying<br />

Pb exposed workers by blood Pb 50 µg/dL found I-V<br />

interpeak latency significantly prolonged (p = 0.03) in<br />

subgroup with higher blood Pb.<br />

Mean blood Pb 45 µg/dL<br />

(range 11 to 80 µg/dL)<br />

Mean blood Pb<br />

Adult 31 µg/dL<br />

Children 22 µg/dL<br />

10 mo avg blood Pb Adults<br />

43 µg/dL<br />

Children 36 µg/dL<br />

Sixty percent <strong>of</strong> the men and 20 percent <strong>of</strong> the women had<br />

abnormal high-frequency thresholds, however there was no<br />

significant relationship with blood Pb and pure tone threshold<br />

at all frequencies. Analysis <strong>of</strong> BAEPs found agreement<br />

between latencies <strong>for</strong> Waves I, <strong>II</strong>I and V and peripheral<br />

hearing status. Interpeak latencies were within normal limits<br />

but no analysis provided with Pb exposure. Workers lived in<br />

a Pb contaminated environment from discarded Pb-acid<br />

storage batteries. There<strong>for</strong>e a measure <strong>of</strong> chronic Pb<br />

exposure may have been more appropriate.<br />

In adults, latencies I, <strong>II</strong>I and I-<strong>II</strong>I and I-V interpeak intervals<br />

were significantly longer than the control group (p < 0.05).<br />

When group stratified by 10 mo avg blood Pb I-<strong>II</strong>I interpeak<br />

interval was longer in the high group. Age and blood Pb<br />

were not studied due to few subjects. The I-<strong>II</strong>I interpeak<br />

interval reflects transmission in the lower brainstem and<br />

V<strong>II</strong>Ith nerve.


AX6-58<br />

Table AX6-3.6 (cont’d). Evoked Potentials and Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Hirata and Kosaka<br />

(1993)<br />

Japan<br />

Murata et al. (1993)<br />

Japan<br />

41 Pb-exposed men from Pb-glass-based colors manufacturing<br />

(n = 20), production <strong>of</strong> Pb electrode plates (n = 8), casting <strong>of</strong> Pbbronze<br />

(n = 4) and casting <strong>of</strong> Pb pipes and plates (n = 9) had mean<br />

age 41 yrs, mean duration <strong>of</strong> exposure 13 yrs. A battery <strong>of</strong> tests<br />

administered including radial nerve conduction study,<br />

electroretinogram (ERG), visual evoked potential (VEP),<br />

brainstem auditory evoked potential (BAER), and short-latency<br />

somatosensory evoked potential (SSEP). Comparison group <strong>of</strong> 39<br />

unexposed used only <strong>for</strong> BAER analysis by Student’s t test.<br />

Correlation and linear regression controlling <strong>for</strong> age examined the<br />

relationship <strong>of</strong> Pb and the other variables.<br />

22 gunmetal foundry workers with age range <strong>of</strong> 32 to 59 yrs and<br />

work duration <strong>of</strong> 1 to 19 yrs and control group matched <strong>for</strong> age,<br />

no chronic disease and no Pb exposure participated. No<br />

significant difference between groups <strong>for</strong> age, height, skin<br />

temperature, alcohol consumption, and yrs <strong>of</strong> schooling. The test<br />

battery consisted <strong>of</strong> visual evoked potential (VEP), brainstem<br />

auditory evoked potential (BAEP), short latency somatosensoryevoked<br />

potential (SSEP), event related potential (P300) and EKG<br />

R-R interval variability. Paired-sample t test examined <strong>for</strong><br />

differences between the matched groups. Dose-effect<br />

relationships examined with partial correlation adjusting <strong>for</strong> age<br />

and stepwise linear regression.<br />

Mean (range) blood Pb<br />

43 µg/dL (13-70)<br />

Mean (range) TWA (based<br />

upon previous 5 yrs)<br />

43 µg/dL (13-70)<br />

Mean (range) duration <strong>of</strong><br />

exposure 13 (0.6-29) yrs<br />

Blood Pb 12 to 64 µg/dL<br />

(no mean provided)<br />

Significant partial correlation after adjusting <strong>for</strong> age<br />

included TWA and radial motor conduction velocity,<br />

blood Pb and sensory conduction velocity, exposure<br />

duration and VEP, blood Pb and SSEP-N20.<br />

Comparison <strong>of</strong> BAERs <strong>of</strong> 15 Pb exposed and 39<br />

controls found interpeak interval <strong>II</strong>I-V was<br />

prolonged significantly. It is not clear why<br />

comparison group only used <strong>for</strong> BAERs.<br />

Considering the large number <strong>of</strong> variables examined<br />

with three exposure terms some <strong>of</strong> the findings could<br />

be by chance alone.<br />

For VEPs, N75 and N145 were significantly<br />

prolonged in the Pb exposed workers. N9-N13<br />

interpeak latency <strong>of</strong> the SSEP was significantly<br />

prolonged. BAEP latencies showed no significant<br />

differences. P300 believed to reflect cognitive<br />

function was prolonged in the Pb workers and<br />

correlated with blood Pb, and PbU. Autonomic<br />

nervous system effects were significantly diminished<br />

<strong>for</strong> CV R-R and <strong>for</strong> a measure <strong>of</strong> parasympathetic<br />

activity C-CVRSA. Fifty percent <strong>of</strong> the outcome<br />

variables showed significant group differences but<br />

there is limited dose effect <strong>for</strong> any outcome within<br />

the exposed group. Small sample size limited<br />

conclusions with 20 outcome variables and 8<br />

biomarkers <strong>of</strong> Pb exposure.


AX6-59<br />

Table AX6-3.7. Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and<br />

Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Dick et al. (1999)<br />

U.S.<br />

Europe<br />

Kovala et al. (1997)<br />

Finland<br />

145 workers from a secondary Pb smelter, mean<br />

age 33 (8.7) and duration <strong>of</strong> employment 5 (4.8)<br />

yrs and 84 comparison workers mean age 30 (9.3)<br />

and duration <strong>of</strong> employment 4 (4.3) yrs had<br />

postural sway testing per<strong>for</strong>med. The analysis <strong>of</strong><br />

exposure with test conditions and covariates used<br />

mixed models.<br />

60 workers in a Pb battery factory with a mean<br />

age <strong>of</strong> 43 (9) yrs and mean exposure duration <strong>of</strong><br />

16 (8) yrs. Quantitative EEG were per<strong>for</strong>med.<br />

Relationship <strong>of</strong> Pb exposure with quantitative<br />

EEG were examined by partial correlation and<br />

regression analyses adjusting <strong>for</strong> age.<br />

Pb workers<br />

Mean (SD) blood Pb 39<br />

(8.5) µg/dL<br />

Mean (SD) ZPP 55 (42.2) µg/dL<br />

Mean (SD) CBL 230<br />

(217.9) µg·yr/dL<br />

Mean (SD) TWA 35 9<br />

(8.5) µg/dL<br />

Comparison workers<br />

Mean (SD) blood Pb 2<br />

(1.7) µg/dL<br />

Mean (SD) tibial Pb 26<br />

(17) mg/kg<br />

Mean (SD) calcaneal Pb<br />

88 (54) mg/kg<br />

Mean (SD) IBL 546<br />

(399)<br />

µg·yr/dL,<br />

Mean (SD) TWA 34 (8.4) µg/dL,<br />

Mean (SD) maximum blood Pb<br />

53 (19) µg/dL<br />

Mean (SD) blood Pb 27<br />

(8.4) µg/dL<br />

The postural sway test had 6 conditions that varied the<br />

challenge to the vestibular and proprioceptive afferents and<br />

visual system. Only blood Pb had a significant effect<br />

primarily on the one leg condition after the effects <strong>of</strong> the<br />

covariates age, height, mass, and race. For the left leg,<br />

exposure slope estimate <strong>for</strong> area (b = 0.0067, t = 3.88,<br />

p = 0.0001) and length (b = 0.0046, t = 4.11, p = 0.0001)<br />

were significant. For the right leg only the exposure slope<br />

estimate <strong>for</strong> length (b = 0.0033, t = 3.02, p = 0.0029) was<br />

significant. Dose effect was only significant when Pb<br />

workers were combined with comparison workers. If<br />

comparison workers with blood Pb level below 12 µg/dL<br />

removed no significant exposure effect was found.<br />

The alpha and/or beta frequencies were more present in<br />

workers with higher long term Pb exposure such as tibial<br />

(p < 0.05) and calcaneal (p < 0.05), IBL (p < 0.01) and<br />

TWA (p < 0.05). Slow alpha in workers was believed to<br />

correlate with increased episodes <strong>of</strong> ‘microdrowsiness’.<br />

The study had no comparison group and did not account <strong>for</strong><br />

the effect <strong>of</strong> smoking and alcohol use or give their usage in<br />

this population.


AX6-60<br />

Table AX6-3.7 (cont’d). Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and<br />

Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia<br />

Iwata et al. (2005)<br />

Japan<br />

Yokoyama et al.<br />

(1997)<br />

Japan<br />

Chia et al. (1994a)<br />

Singapore<br />

Chia et al. (1996c)<br />

Singapore<br />

121 workers from a battery recycling plant<br />

and 60 age matched comparison group, mean<br />

age 46 (11) yrs. Height, body weight, body<br />

mass index, and alcohol use was similar in<br />

both groups. Pb group had significantly<br />

more smokers. ANCOVA used to evaluate<br />

postural sway after controlling <strong>for</strong> age,<br />

height, and smoking and drinking status.<br />

Benchmark dose level was calculated as the<br />

95% lower confidence limit <strong>of</strong> the<br />

benchmark dose.<br />

49 chemical workers exposed to Pb stearate,<br />

mean age 48 (1.3) yrs and 23 controls, mean<br />

age 47 (2.5) had postural sway evaluated.<br />

ANCOVA examined group differences after<br />

adjusting <strong>for</strong> covariates.<br />

60 Pb storage workers, mean age 32 (7.7) yrs<br />

and 60 controls, mean age 35 (7.4) had<br />

postural sway parameters measured.<br />

ANCOVA used to examine group differences<br />

after adjusting <strong>for</strong> covariates. Linear<br />

regression examined relationship between Pb<br />

exposure and postural sway.<br />

The same 60 Pb storage workers as above<br />

and 60 control had postural sway data<br />

examined <strong>for</strong> contribution <strong>of</strong> cumulative<br />

blood Pb fractionated over 10 yrs <strong>of</strong><br />

exposure.<br />

Mean (SD) blood Pb 40<br />

(15) µg/dL<br />

Referent<br />

Not done<br />

Mean (SD) blood Pb 18<br />

(1.0) µg/dL<br />

Mean (SD) maximum<br />

blood Pb 48 (3.8) µg/dL<br />

Mean (SD) TWA 24<br />

(1.3) µg/dL<br />

Mean (SD) Cumulative<br />

blood Pb 391<br />

(48.2) µg·yr/dL<br />

Pb workers<br />

Mean (SD) blood Pb 36<br />

(11.7) µg/dL<br />

Controls<br />

Mean (SD) blood Pb 6<br />

(2.4) µg/dL<br />

Pb workers<br />

Mean (SD) blood Pb 36<br />

(11.7) µg/dL<br />

Controls<br />

Mean (SD) blood Pb 6<br />

(2.4) µg/dL<br />

Except <strong>for</strong> sagittal sway, all postural sway parameters with eyes open<br />

were significantly larger in Pb workers. Blood Pb level in workers<br />

was significantly associated with to sagittal sway at 1-2 Hz and 2-4<br />

Hz with eyes open, and sagittal and transversal sways at 1-2 Hz and<br />

2-4 Hz with eyes closed. The mean benchmark dose level <strong>of</strong> current<br />

blood Pb level <strong>for</strong> postural sway was 14.3 µg/dL <strong>for</strong> the linear model<br />

and 14.6 µg/dL <strong>for</strong> the K power model.<br />

There were significant increases in sway in all directions at high and<br />

low frequencies with eyes open and eyes closed (p < 0.05).<br />

Regression analysis found blood Pb associated with sway in the<br />

anterior-posterior direction, 0.5-1Hz (0.321, p = 0.03), 1-2Hz (0.313,<br />

p = 0.04) and TWA associated with right to left sway (0.326,<br />

p = 0.02) after adjustment <strong>for</strong> the covariates age, height, weight and<br />

alcohol consumption. The authors conclude that change in the<br />

vestibulo-cerebellum is affected by blood Pb while in the anterior<br />

cerebellar lobe is affected by past Pb exposure.<br />

Computerized postural sway measurements found Pb workers<br />

have poorer postural stability that increased with eyes closed<br />

(p < 0.01). Regression analysis adjusting <strong>for</strong> age, height, and<br />

weight found no significant association with blood Pb.<br />

The Pb exposed group had significantly poorer per<strong>for</strong>mance on all<br />

postural sway parameters with eyes closed compared to controls after<br />

adjusting <strong>for</strong> height, weight, age and drinking habits (p < 0.01).<br />

All postural sway parameters with eyes closed were significantly<br />

associated with IBL <strong>for</strong> the 2 yrs prior to testing (n = 23, p < 0.05).


AX6-61<br />

Table AX6-3.7 (cont’d). Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and<br />

Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Ratzon et al. (2000)<br />

Israel<br />

Teruya et al. (1991)<br />

Japan<br />

Ishida et al. (1996)<br />

Japan<br />

63 Pb battery workers, mean age 39 (8.7) yrs<br />

and 48 controls mean age 36 (11.8) yrs,<br />

matched <strong>for</strong> age with similar sex and<br />

education, had postural control measured.<br />

Group differences examined with t test.<br />

Dose-effect relations assessed with<br />

Pearson = s correlation coefficients. Linear<br />

regression done with exposure category as<br />

major predictor.<br />

172 Pb exposed workers, mean age 34<br />

(18.4-57.4) yrs had cardiac autonomic<br />

nervous system evaluated by R-R intervals<br />

variation with respiration measured.<br />

128 workers in the ceramic painting industry,<br />

58 men, mean age 55 (11.7) yrs and<br />

70 women, mean age 52 (9.2) yrs had<br />

measures <strong>of</strong> sympathetic function by<br />

variations in R-R interval on EKG and<br />

changes in finger blood flow with postural<br />

changes using Doppler flowmetry.<br />

Correlation analyses and linear regression<br />

examined relationship <strong>of</strong> finger blood flow<br />

and Pb exposure after adjusting <strong>for</strong><br />

covariates.<br />

Mean past blood Pb<br />

38 µg/dL<br />

Mean yrs employed 11<br />

Cumulative Pb determined<br />

by avg blood Pb Η yrs<br />

employed<br />

Mean (range) blood Pb 36<br />

(5-76) µg/dL<br />

Men<br />

Mean (SD) blood Pb 17<br />

(2.1) µg/dL<br />

Mean (SD) ALAD% 61.6<br />

(28.3)%<br />

Women<br />

Mean (SD) blood Pb 11<br />

(1.7) µg/dL<br />

Mean (SD) ALAD% 72.6<br />

(20.8)%<br />

Using a computerized sway measurement system the exposed<br />

workers had significantly increased mean body oscillations with eyes<br />

closed (p < 0.01) and head tilted <strong>for</strong>ward (p < 0.001). Partial<br />

correlation adjusting <strong>for</strong> education, c<strong>of</strong>fee consumption, hrs <strong>of</strong> sleep<br />

and estimate <strong>of</strong> health was significant only <strong>for</strong> total Pb exposure and<br />

increased body oscillations with head tilted <strong>for</strong>ward (∃ = 2.25,<br />

p = 0.0089). In order to maintain balance Pb exposed workers<br />

required increased oscillations when visual and vestibular inputs<br />

were altered.<br />

Age adjustment controlled <strong>for</strong> by use <strong>of</strong> ratios <strong>of</strong> predicted to<br />

observed values. A significant dose related decrease <strong>of</strong> R-R interval<br />

variation during deep breathing was present in 132 workers with<br />

stable blood Pb over the past yr (p < 0.01). This finding was more<br />

prominent in younger workers with blood Pb ∃30 µg/dL but a mild<br />

decrease present at blood Pb ∃20 µg/dL. A decrease in R-R interval<br />

variation indicates decreased cardiac parasympathetic function.<br />

22% had blood Pb >20 µg/dL, and 43% had ALAD%


AX6-62<br />

Table AX6-3.7 (cont’d). Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and<br />

Occupational <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Niu et al. (2000)<br />

China<br />

44 Pb-exposed workers (17 men, 27 women)<br />

from Pb printing houses, mean age 35 (4.9)<br />

and education 9.3 (no SD) yrs and 34<br />

controls (19 men and 15 women), mean age<br />

33 (7.4) yrs and education 9.5 (no SD) yrs<br />

had autonomic nervous system examined.<br />

ANCOVA controlling <strong>for</strong> age, sex and<br />

education examined group differences and<br />

linear regression <strong>for</strong> dose-response<br />

relationship.<br />

Pb workers<br />

Mean (SD) blood Pb 29<br />

(26.5) µg/dL<br />

(8 workers blood Pb<br />

exceeded 50 µg/dL)<br />

Controls<br />

Mean (SD) blood Pb 13<br />

(9.9) µg/dL<br />

(1 control blood Pb<br />

exceeded 50 µg/dL)<br />

Niu et al. (2000) examined autonomic nervous system in 44 Pb<br />

exposed workers, mean blood Pb 29 µg/dL, and 34 controls, mean<br />

blood Pb, 13 µg/dL. Linear regression found association between<br />

blood Pb and decreased R-R interval with valsalva (F/T 2.349,<br />

p < 0.05) and duration <strong>of</strong> Pb exposure and decreased R-R interval<br />

with deep breathing (F/T 3.263, p < 0.01) after adjusting <strong>for</strong> age, sex,<br />

education, smoking and drinking. In the same study, quantitative<br />

EEG found significant abnormalities in the Pb-exposed workers,<br />

dominant low amplitude in 59%, dominant beta frequency in 42%<br />

and abnormalities in 81%.


AX6-63<br />

Table AX6-3.8. Occupational Exposure to Organolead and Inorganic <strong>Lead</strong> in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Schwartz et al. (1993)<br />

U.S.<br />

Stewart et al. (1999)<br />

U.S.<br />

Two hundred and twenty-two current<br />

employees that manufactured tetraethyl Pb<br />

participated in a study to determine if there<br />

was impairment on a neurobehavioral battery<br />

associated with a measure <strong>of</strong> cumulative<br />

exposure to organic and inorganic Pb derived<br />

from 12 yrs <strong>of</strong> air sampling. Mean age was<br />

44 (8.7) yrs, education 13 (1.7) yrs.<br />

543 <strong>for</strong>mer organolead workers, mean yrs<br />

since last exposure18, examined <strong>for</strong> ongoing<br />

neurobehavioral impairment related to past<br />

Pb exposure. Thirty-eight % were age 60 or<br />

older, predominantly white, 93% had at least<br />

a high school degree. Linear regression<br />

assessed the relationship between Pb dose<br />

and neurobehavioral function adjusting <strong>for</strong><br />

the covariates.<br />

Mean (SD) cumulative Pb<br />

exposure (inorganic and<br />

organic) 869 (769) µg·yr/m 3<br />

Mean (SD) yrs <strong>of</strong> exposure<br />

13 (9.5)<br />

Mean (SD) tibial Pb 14<br />

(9.3) µg/g<br />

Mean (SD) peak tibial bone<br />

Pb (extrapolated back using a<br />

clearance half-time <strong>of</strong> Pb in<br />

tibia <strong>of</strong> 27 yrs) 24<br />

(17.4) µg/g<br />

Mean (SD) DMSA chelatable<br />

Pb 19 (17.2) µg (urine<br />

collected <strong>for</strong> 4 hrs)<br />

Exposure was divided into 4 groups with the lowest <strong>for</strong> yrs <strong>of</strong><br />

exposure and cumulative Pb exposure serving as the reference group.<br />

After adjustments <strong>for</strong> premorbid intellectual ability, age, race, and<br />

alcohol consumption, cumulative Pb exposure had differential<br />

association poorer per<strong>for</strong>mance in many cognitive domains but most<br />

<strong>of</strong>ten in manual dexterity and verbal memory/learning. Per<strong>for</strong>mance<br />

on tests associated with exposure was 5 to 22% lower in the highest<br />

groups when compared with the low exposure reference group.<br />

Peak tibial Pb was a significant predictor <strong>of</strong> poorer per<strong>for</strong>mance on<br />

Vocabulary (∃ = !0.063, p = 0.02), serial digit learning (∃ = !0.043,<br />

p = 0.04), RAVLT trial 1 (∃ = !0.054, p = 0.03), RAVLT recognition<br />

(∃ = !0.019, p = 0.03), Trails B (∃ = !0.002, p = 0.03), finger tapping<br />

nondominant (∃ = !0.042, p = 0.02), Purdue pegboard dominant<br />

(∃ = !0.043, p = 0.00), nondominant (∃ = !0.49, p = 0.00), both<br />

(∃ = !0.038, p = 0.00), assembly (∃ = !0.133, p = 0.00), and Stroop<br />

(∃ = !0.014, p = 0.00).<br />

Current tibial Pb had similar associations – Vocabulary (∃ = 0.103,<br />

p = 0.04), Digit Symbol (∃ = !0.095, p = 0.05), finger tapping<br />

dominant (∃ = !0.87, p = 0.02), finger tapping nondominant<br />

(∃ = 0.102, p = 0.00), Purdue Pegboard dominant (∃ = !0.065,<br />

p = 0.01), nondominant (∃ = !0.091, p = 0.00), both (∃ = !0.068,<br />

p = 0.00), assembly (∃ = !0.197, p = 0.03 ), and Stroop (∃ = 0.017,<br />

p = 0.01).<br />

DMSA-chelatable Pb was only significantly associated with choice<br />

reaction time (∃ = !0.001, p = 0.01).


AX6-64<br />

Table AX6-3.8 (cont’d). Occupational Exposure to Organolead and Inorganic <strong>Lead</strong> in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Stewart et al. (2002)<br />

U.S.<br />

Balbus et al. (1997)<br />

U.S.<br />

Balbus et al. (1998)<br />

U.S.<br />

From the above group <strong>of</strong> <strong>for</strong>mer organolead<br />

workers 535 were re-examined twice or four<br />

times over a four yr period. Also a<br />

nonexposed control group <strong>of</strong> 118 had repeat<br />

examinations. Mean age at first visit<br />

exposed/controls 56 (7.4)/59 (7.0),<br />

percentage with at least a high school<br />

education 66/71.2.<br />

222 organolead manufacturing workers,<br />

mean age 44 (8.7) yrs and 62 nonexposed<br />

referents, mean age 43 (10) yrs per<strong>for</strong>med<br />

simple visual reaction time (SVRT). Linear<br />

regression examined relationship between Pb<br />

exposure and mean RT, median RT and<br />

standard deviation <strong>of</strong> RT after controlling <strong>for</strong><br />

covariates.<br />

A second publication further examined the<br />

above data <strong>for</strong> relationship <strong>of</strong> interstimulus<br />

interval (ISI) and Pb exposure.<br />

1st examination<br />

Mean (SD) blood Pb 5<br />

(2.7) µg/dL<br />

Mean (SD) tibia Pb 14<br />

(9.3) µg/g<br />

Mean (SD) peak tibia Pb<br />

23 (16.5) µg/g<br />

Mean (SD) exposure duration<br />

8 (9.7) yrs<br />

Mean (SD) duration since last<br />

exposure 16 (11.7) yrs<br />

Mean (SD) blood Pb 20<br />

(9.5) µg/dL<br />

Mean (SD) peak urine Pb level<br />

143 (130) µg/L<br />

On 17 <strong>of</strong> 19 neurobehavioral tests, <strong>for</strong>mer organolead workers<br />

demonstrated greater annual decline in adjusted test scores<br />

compared to controls with significant differences <strong>for</strong> Rey complex<br />

Figure copy, RAVLT Trial 1 and RAVLT recognition. Annual<br />

declines in per<strong>for</strong>mance showed greater age-related change in Pb<br />

workers compared to controls <strong>for</strong> block design, digit symbol,<br />

serial digit learning, finger tapping and Trails A. Blood Pb did not<br />

predict annual change scores but peak tibial Pb did <strong>for</strong> symbol<br />

digit, Rey Complex Figure delayed recall, RAVLT trial 1,<br />

RAVLT delayed recall, Purdue pegboard (1 measure) and the<br />

Stroop. For these 6 tests it was determined that an increase <strong>of</strong><br />

15.7 µg/g bone mineral <strong>of</strong> peak tibia Pb was equivalent in its<br />

effect on annual test decline to 5 more yrs <strong>of</strong> age at baseline.<br />

Authors conclude that data supports ongoing cognitive decline<br />

associated with past occupational exposure to Pb.<br />

Same as above Short ISIs <strong>of</strong> 1-3 seconds had no relationship with Pb exposure<br />

while ISIs <strong>of</strong> 4-6 seconds were significantly associated with blood<br />

Pb (∃ = 0.06 [SE 0.02], p = 0.02 along with ISIs <strong>of</strong> 7-10 seconds<br />

(∃ = 0.05 [SE 0.02], p = 0.03). ISIs 7-10 seconds with peak urine<br />

Pb levels (∃ = 64.29 [SE 21.86], p < 0.01).


AX6-65<br />

Table AX6-3.8 (cont’d). Occupational Exposure to Organolead and Inorganic <strong>Lead</strong> in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Stewart et al. (2002)<br />

U.S.<br />

Tassler et al. (2001)<br />

U.S.<br />

Bolla et al. (1995)<br />

U.S.<br />

Mitchell et al. (1996)<br />

U.S.<br />

Population as described in Stewart et al.<br />

(1999) and Schwartz et al. (2000b). Data<br />

on 20 neurobehavioral tests from 529<br />

<strong>for</strong>mer organolead workers were<br />

evaluated to determine if the previously<br />

described relationship with bone Pb<br />

levels is influenced by the apolipoprotein<br />

E (ApoE) genotype.<br />

490 <strong>for</strong>mer organolead workers, mean<br />

age 58 (7.5) yrs. The peripheral nervous<br />

system was examined with sensory<br />

pressure thresholds, and pinch and grip<br />

strength.<br />

190 current workers in organolead<br />

manufacturing (from the 222 described in<br />

Schwartz et al., 1993) mean age 45 (8)<br />

yrs compared to 52 referents, mean age<br />

45 (8) yrs and 144 solvent exposed<br />

workers, mean age 42 (8) yrs.<br />

58 organolead workers, self-selected <strong>for</strong><br />

a clinical evaluation. Mean age 45 (7.1)<br />

yrs.<br />

Mean (SD) blood Pb 5<br />

(2.6) µg/dL<br />

Mean (SD) DMSA-chelatable Pb<br />

19 (16.3) µg<br />

Mean (SD) current tibia Pb<br />

15 (9.4) µg/g<br />

Mean (SD) peak tibia Pb 24<br />

(17.6) µg/g<br />

IH found organic Pb was 65 to<br />

70% <strong>of</strong> exposure in production<br />

area.<br />

Mean (SD) weighted avg blood<br />

Pb 24 (9.4) µg/dL<br />

Mean (SD) blood Pb 19<br />

(6.5) µg/dL<br />

Mean (SD) lifetime blood Pb 26<br />

(9.1) µg/dL<br />

Mean (SD) lifetime urine Pb 51<br />

(18.8) µg/L<br />

In 20 linear regression models, coefficients <strong>for</strong> the ApoE and tibia Pb<br />

interaction term were negative in 19 with significance reached <strong>for</strong> digit<br />

symbol (∃ = !0.109 [SE 0.054], p # 0.05), Purdue pegboard dominant<br />

(∃ = 0.068 [SE 0.028], p # 0.05) and complex reaction time (∃ = !0.003<br />

[SE 0.001], p#0.05) and borderline significance existed <strong>for</strong> symbol digit<br />

(∃ = !0.046 [SE 0.026], p # 0.10), Trails A (∃ = !0.303, [SE 0.164]<br />

p # 0.10) and Stroop (∃ = !0.013 [SE 0.008], p # 0.10). The slope <strong>of</strong> the<br />

relation between tibia Pb and neurobehavioral outcome was more<br />

negative in those individuals with at least one ε4 allele than individuals<br />

without this allele. It is suggested that the presence <strong>of</strong> one Apo-ε-4 allele<br />

increases the risk <strong>of</strong> persistent central nervous system effects <strong>of</strong> Pb.<br />

No strong association was found between Pb biomarkers and measures<br />

<strong>of</strong> sensory and motor function after adjusting <strong>for</strong> age. The authors<br />

attributed the findings to decreased sensitivity <strong>of</strong> the peripheral nerves in<br />

this dose range <strong>of</strong> inorganic Pb or the possibility <strong>of</strong> differential repair in<br />

the peripheral nervous system compared to the central nervous system.<br />

Pb and solvent exposure associated with adverse effects on tests <strong>of</strong><br />

manual dexterity. When compared to the solvent group Pb exposure had<br />

greater impairment on memory and learning and less on executive/motor<br />

tests. An elevated neuropsychiatric score was present in 43% <strong>of</strong> the Pb<br />

group, 15% <strong>of</strong> the solvent and 7% <strong>of</strong> the referent group.<br />

The most common symptoms were memory loss 74%, joint pain 56%,<br />

trouble sleeping 54%, irritability 51%, paresthesia 49%, fatigue 49%,<br />

nightmares 35%, moodiness 28%, headaches 21% and depression 21%.<br />

Of the 31 workers receiving nerve conduction studies, 29% were normal,<br />

carpal tunnel syndrome 36%, cubital tunnel syndrome 3%, median<br />

neuropathy 3%, ulnar neuropathy 23%, mononeuropathy in lower<br />

extremity 5%, tarsal tunnel syndrome 7% and sensorimotor<br />

polyneuropathy 36%. 39 workers had neurobehavioral evaluation with<br />

64% had abnormal tests <strong>of</strong> which 46% were considered to be consistent<br />

with a toxic exposure.


AX6-66<br />

Table AX6-3.9. Other Neurological Outcomes Associated with <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Louis et al. (2005)<br />

New York<br />

Louis et al. (2003)<br />

New York<br />

Kamel et al. (2002)<br />

Massachusetts<br />

63 cases <strong>of</strong> essential tremor<br />

(ET) and 101 controls,<br />

similar <strong>for</strong> age, 67 (16.6) and<br />

65 (11.1) yrs, education,<br />

gender and ethnicity were<br />

examined <strong>for</strong> interaction <strong>of</strong><br />

blood Pb and ALAD gene<br />

polymorphisms and increased<br />

odds <strong>of</strong> ET.<br />

100 cases <strong>of</strong> ET and 143<br />

controls matched <strong>for</strong> age, sex,<br />

and ethnicity.<br />

The relationship between<br />

blood Pb and ET was<br />

examined.<br />

109 cases <strong>of</strong> ALS and 256<br />

controls matched <strong>for</strong> age, sex<br />

and region <strong>of</strong> residence<br />

examined the relation <strong>of</strong> Pb<br />

and ALS.<br />

ET<br />

Mean (SD) blood Pb 4 (2.2) µg/dL<br />

Controls<br />

Mean (SD) blood Pb 3 (1.5) µg/dL<br />

2 ET cases but no controls had blood Pb<br />

>10 µg/dL<br />

ET<br />

Mean blood Pb 3 µg/dL<br />

Controls<br />

Mean blood Pb 2 µg/dL<br />

Cases/controls<br />

Mean (SD) blood Pb 5 (0.4) / 3 (0.4) µg/dL<br />

3 cases and no controls had blood Pb >10 µg/dL<br />

Mean (SD) patella Pb 21 (2.1) / 17 (2.0) µg/g<br />

5 cases and 1 control had patella Pb levels<br />

>50 µg/g<br />

Mean (SD) tibia Pb 15 (1.6) / 11 (1.6) µg/g<br />

2 cases and no controls had tibia Pb >50 µg/g.<br />

Of the 63 ET cases 18 (29%) vs. 17 (17%) <strong>of</strong> 101 controls had an<br />

ALAD2 allele (OR = 1.98 [95% CI: 0.93, 4.21]; p = 0.077). When<br />

log blood Pb was examined by presence <strong>of</strong> ALAD2 allele in ET, log<br />

blood Pb was highest in ET cases with and ALAD2 allele,<br />

intermediate in ET cases without an ALAD2 allele and lowest in<br />

controls (test <strong>for</strong> trend, ∃ = 0.10; p = 0.001). When ALAD2 allele<br />

was present, blood Pb was significantly associated with odds <strong>of</strong> ET<br />

(OR = 80.29 [95% CI: 3.08, 2.096]; p = 0.008). This increased<br />

odds <strong>of</strong> ET with an ALAD2 allele was 30 times greater than in an<br />

individual with only an ALAD1 alleles. In the highest log blood Pb<br />

tertile, ALAD2 allele was present in 22% <strong>of</strong> ET cases and 5% <strong>of</strong><br />

controls. It was proposed that increased blood Pb along with the<br />

ALAD2 allele could affect the cerebellum and thereby increase the<br />

risk <strong>of</strong> tremor.<br />

Ten cases and 7 controls had bone Pb levels measured that were<br />

significantly correlated with blood Pb suggesting that higher blood<br />

Pb may have occurred in the past. Total tremor score was<br />

correlated with blood Pb (r = 0.14, p = 0.03). Logistic regression<br />

adjusting <strong>for</strong> age and current cigarette smoking found the odds ratio<br />

<strong>for</strong> ET was 1.19 (95% CI: 1.03, 1.37) per unit increase in blood Pb.<br />

Blood Pb was higher in those 39 ET cases with no family history.<br />

Both current and lifetime prevalence <strong>of</strong> occupational Pb exposure<br />

was the same in ET cases and controls but those with history <strong>of</strong><br />

occupational exposure did have a higher blood Pb than those<br />

without this history (median, 3.1 µg/dL vs. 2.4 µg/dL, p = 0.004).<br />

Increased risk <strong>of</strong> ALS was found <strong>for</strong> history <strong>of</strong> occupational Pb<br />

exposure (adjusted OR = 1.9 [95% CI: 1.1, 3.3]) increased lifetime<br />

days <strong>of</strong> exposure (adjusted OR = 2.3 [95% CI: 1.1, 4.9]).<br />

Association <strong>of</strong> blood Pb and ALS (adjusted OR = 1.9 [95% CI: 1.4,<br />

2.6]). Elevation in both blood Pb and patella and tibia bone Pb was<br />

found in ALS cases though the precision <strong>of</strong> these measurements<br />

was questioned (Patella Pb adjusted OR = 3.6 [95% CI: 0.6, 20.6]<br />

and tibia Pb adjusted OR = 2.3 [95% CI: 0.4, 14.5]). There<strong>for</strong>e,<br />

this study found Pb exposure from historical questionnaire data and<br />

biological markers associated with ALS.


AX6-67<br />

Table AX6-3.9 (cont’d). Other Neurological Outcomes Associated with <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Kamel et al. (2003)<br />

Massachusetts<br />

Armon et al. (1991)<br />

Minnesota<br />

Europe<br />

Chancellor et al.<br />

(1993)<br />

Scotland<br />

1990-1991<br />

Gunnarsson et al.<br />

(1992)<br />

Sweden<br />

1990<br />

As above, the same data was used to<br />

determine the associations <strong>of</strong> ALS with<br />

polymorphism in ALAD and the vitamin D<br />

receptor (VDR) and the influence <strong>of</strong><br />

genotype.<br />

A case-control design with 47 ALS patients,<br />

mean age 61 with involvement <strong>of</strong> upper and<br />

lower motor neurons and 201 controls, mean<br />

age 62. For the Pb exposure analysis 45 male<br />

matched pairs were examined.<br />

A case-control design 103 ALS patients from<br />

the Scottish Motor Neuron Disease Register<br />

and matched community controls.<br />

Differences in potential occupational<br />

exposures were determined between cases<br />

and controls.<br />

A case-control study <strong>of</strong> 92 cases <strong>of</strong> MND<br />

and 372 controls. MND included ALS,<br />

progressive bulbar paresis (PBP), and<br />

progressive muscular atrophy (PMA).<br />

Relation <strong>of</strong> MND to risk factors including<br />

occupational exposure examined.<br />

Same as above The ALAD2 allele was associated with a 2-fold increase risk <strong>of</strong> ALS<br />

after adjustment <strong>for</strong> the covariates, age, sex, region, education and<br />

physical activity adjusted (OR = 1.9 [95% CI: 0.60, 6.3]).<br />

Additionally adjusting <strong>for</strong> blood Pb strengthened the association <strong>of</strong><br />

ALAD2 and ALS risk adjusted (OR = 3.6 [95% CI: 0.9, 15]). This<br />

was not found <strong>for</strong> bone Pb or occupational history <strong>of</strong> Pb exposure<br />

(patella-adjusted OR = 2.1 [95% CI: 0.61, 6.9]; tibial-adjusted (OR =<br />

2.2 [95% CI: 0.66, 7.3]; occupational history-adjusted<br />

(OR = 2.4 [95% CI: 0.67, 8.7]). VDR was not associated with Pb or<br />

ALS risk.<br />

Lifetime exposure to Pb <strong>of</strong><br />

200 hrs or more (yrs on job x<br />

hrs spent per wk)<br />

Exposure to Pb obtained by<br />

lifetime employment history<br />

from Office <strong>of</strong> Population and<br />

Censuses and Surveys.<br />

Physician’s record review and<br />

direct interview questionnaire.<br />

Exposure in<strong>for</strong>mation<br />

obtained by self-administered<br />

questionnaire.<br />

Of 13 discordant pairs <strong>for</strong> Pb exposure, 11 were in ALS patient. The<br />

relative risk was 5.5 (95% CI: 1.44, 21.0). A dose-response was<br />

weakened by 3 controls with highest lifetime exposure. Men with<br />

ALS worked more <strong>of</strong>ten at blue collar jobs and significantly more<br />

time welding (p < 0.01). These results expanded a prior pilot study<br />

that found a higher incidence <strong>of</strong> heavy metal exposure in ALS cases.<br />

Odds ratio <strong>for</strong> manual labor in ALS patients was 2.6 (95% CI: 1.1,<br />

6.3). Occupational exposure to Pb was more common in ALS<br />

patients (OR = 5.7 [95% CI: 1.6, 30]).<br />

Exposure to heavy metals primarily from welding had an increased<br />

Mantel-Haenszel OR = 3.7 [95% CI: 1.1, 13.0].


AX6-68<br />

Table AX6-3.9 (cont’d). Other Neurological Outcomes Associated with <strong>Lead</strong> Exposure in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Guidetti et al. (1996)<br />

Italy<br />

Vinceti et al. (1997)<br />

Italy<br />

A retrospective incidence, prevalence, and<br />

mortality survey <strong>of</strong> ALS in northern Italy<br />

was per<strong>for</strong>med.<br />

19 ALS cases, mean age 66 (14) yrs and<br />

39 controls, mean age 64 (12.9) yrs.<br />

Mean air Pb 3 µg/m 3 in<br />

1975 to 1 µg/m 3 in 1985;<br />

blood Pb in monitored<br />

children decreased 18, 14,<br />

and 11 µg/dL in same time<br />

period.<br />

Sporadic ALS<br />

Mean (SD) blood Pb 13<br />

(6.8) µg/dL<br />

Controls<br />

Mean (SD) blood Pb<br />

11 (4.4) µg/dL<br />

The area studied had documented Pb pollution <strong>for</strong> yrs. Based upon<br />

79 cases incidence and prevalence rate were comparable to the<br />

surrounding area.<br />

There were no cases familial ALS. Blood Pb between ALS cases<br />

and controls was not significantly different. Blood Pb was associated<br />

with disability due to ALS but no support was found <strong>for</strong> involvement<br />

<strong>of</strong> Pb in the etiology <strong>of</strong> sporadic ALS.


ANNEX TABLES AX6-4<br />

AX6-69


AX6-70<br />

Table AX6-4.1. Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Kim et al. (1996)<br />

Boston, MA<br />

1979-1994<br />

459 men in the Normative Aging Study; periodic<br />

exams every 3-5 yrs.<br />

Mean serum creatinine at baseline<br />

1.2 mg/dL<br />

Random effects modeling, adjusting <strong>for</strong> baseline age,<br />

time since initial visit, body mass index, smoking<br />

status, alcohol ingestion, education level,<br />

hypertension (defined as blood pressure ≥160 or 95<br />

mm Hg or anti-hypertensive medication use), and, in<br />

longitudinal analysis, baseline serum creatinine and<br />

time between visits.<br />

Mean (SD) blood Pb at<br />

baseline<br />

9.9 (6.1) µg/dL<br />

Blood Pb levels from stored<br />

red blood cells were adjusted<br />

<strong>for</strong> hematocrit; the assay and<br />

adjustment procedure were<br />

validated against freshly<br />

collected samples. Storage<br />

tubes were shown to be Pb<br />

free.<br />

Cross-sectional<br />

Positive association between log trans<strong>for</strong>med blood Pb<br />

and concurrent serum creatinine. 10-fold higher blood Pb<br />

level associated with 0.08 mg/dL higher serum creatinine<br />

(95% CI: 0.02, 0.13).<br />

Association stronger in participants with lower peak blood<br />

Pb levels. ∃ coefficient (95% CI) in the 141 participants<br />

whose peak blood Pb #10 µg/dL: 0.06 (95% CI: 0.023,<br />

0.097).<br />

Longitudinal<br />

Positive association between log trans<strong>for</strong>med blood Pb<br />

and change in serum creatinine over subsequent follow-up<br />

period in participants whose peak blood Pb was #25 µg/dL<br />

∃ coefficient 0.027 (95% CI: 0.0, 0.054)<br />

Slope <strong>of</strong> age-related increase in serum creatinine steeper in<br />

group with highest quartile <strong>of</strong> time weighted avg Pb<br />

exposure compared to the lowest quartile.


AX6-71<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Muntner et al. (2003)<br />

U.S.<br />

1988-1994<br />

Blood Pb levels measured in 15,211 adult subjects enrolled in<br />

the NHANES <strong>II</strong>I study.<br />

Study cohort representative <strong>of</strong> U.S. population; non-Hispanic<br />

African Americans, Mexican Americans, the elderly and<br />

children over-sampled to allow stable estimates in these groups.<br />

Hypertension defined as blood pressure ∃140 and/or 90 mm Hg<br />

and/or current antihypertensive medication use. Based on<br />

evidence <strong>of</strong> interaction between blood Pb and hypertension, the<br />

population was stratified by hypertension <strong>for</strong> further analysis.<br />

4,813 hypertensives; 10,398 normotensives.<br />

Elevated serum creatinine (%)<br />

Defined as ∃99th percentile <strong>of</strong> each race-gender specific<br />

distribution <strong>for</strong> healthy young adults [age 20-39 without<br />

hypertension or diabetes].<br />

11.5 % (hypertensives)<br />

1.8 % (normotensives)<br />

Chronic kidney disease (%)<br />

Chronic kidney disease defined as GFR


AX6-72<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Payton et al. (1994)<br />

Boston, MA<br />

1988-1991<br />

Shadick et al. (2000)<br />

Boston, MA<br />

1991-1996<br />

Blood Pb levels measured in 744 men enrolled in the<br />

Normative Aging Study.<br />

Serum creatinine<br />

1.3 mg/dL<br />

Measured creatinine clearance<br />

88.2 mL/min<br />

Calculated creatinine clearance<br />

71 mL/min<br />

Multiple linear regression adjusting <strong>for</strong> age, body<br />

mass index, analgesic and diuretic use, alcohol<br />

consumption, smoking status, systolic/ diastolic blood<br />

pressure.<br />

777 participants in all male Normative Aging Study.<br />

Mean blood Pb<br />

8.1 µg/dL<br />

Blood Pb levels below the<br />

limit <strong>of</strong> detection <strong>of</strong> 5 µg/dL<br />

were recoded as 4 µg/dL (n<br />

not stated).<br />

Mean blood Pb<br />

5.9 µg/dL<br />

Mean tibia Pb<br />

20.8 µg/g bone mineral<br />

Mean patella Pb<br />

30.2 µg/g bone mineral<br />

In blood Pb negatively associated with ln measured<br />

creatinine clearance (∃ = !0.04 [95% CI: !0.079, !0.001]).<br />

10 µg/dL higher blood Pb associated with a 10.4 mL/min<br />

lower creatinine clearance.<br />

Borderline significant associations (p < 0.1) between<br />

blood Pb and both serum creatinine (∃ = 0.027; neither SE<br />

nor CI provided) and estimated creatinine clearance<br />

(∃ = !0.022; neither SE nor CI provided).<br />

A significant association between patella Pb and uric acid<br />

(∃ = 0.0007 [95% CI: 0.001, 0.013]; p = 0.02) was found,<br />

after adjustment <strong>for</strong> age, BMI, diastolic blood pressure,<br />

alcohol ingestion, and serum creatinine. Borderline<br />

significant associations between tibia (p = 0.06) and blood<br />

Pb (p = 0.1) and uric acid were also observed. Notably<br />

these associations were significant even after adjustment<br />

<strong>for</strong> blood pressure and renal function, providing further<br />

evidence that low level Pb increases uric acid. Fifty-two<br />

participants had gout; Pb dose was not associated with risk<br />

<strong>for</strong> gout.


AX6-73<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Tsaih et al. (2004)<br />

Boston, MA<br />

1991-~2001<br />

448 men enrolled in the Normative Aging Study.<br />

Baseline Serum Creatinine<br />

1.3 mg/dL<br />

Longitudinal analysis <strong>of</strong> data from 2 evaluations a<br />

mean <strong>of</strong> 6 yrs apart.<br />

Annual change in serum creatinine = (follow-up<br />

serum creatinine – baseline serum creatinine) / yrs <strong>of</strong><br />

follow-up.<br />

Covariates assessed = age, age squared, body mass<br />

index, hypertension (defined as blood pressure ∃160<br />

or 95 mm Hg or physician diagnosis with use <strong>of</strong><br />

antihypertensive medication), diabetes (defined as use<br />

<strong>of</strong> oral hypoglycemic drugs or insulin or reported<br />

physician diagnosis), smoking status, alcohol<br />

consumption, analgesic use, and, in longitudinal<br />

models, baseline serum creatinine and its square.<br />

Six percent and 26% <strong>of</strong> subjects had diabetes and<br />

hypertension, at baseline, respectively.<br />

Mean (SD) baseline blood Pb<br />

6.5 (4.2) µg/dL<br />

Mean (SD) baseline tibia Pb<br />

21.5 (13.5) µg/g bone mineral<br />

Mean (SD) baseline patella Pb<br />

32.4 (20.5) µg/g<br />

Mean blood Pb levels and serum creatinine decreased<br />

significantly over the follow-up period in the group. Pb<br />

dose not associated with change in creatinine overall.<br />

Significant interaction <strong>of</strong> blood and tibia Pb with diabetes<br />

in predicting annual change in serum creatinine.<br />

∃ (95% CI) <strong>for</strong> natural ln baseline blood Pb 0.076 (0.031,<br />

0.121) compared to 0.006 (!0.004, 0.016) <strong>for</strong> nondiabetics.<br />

∃ (95% CI) <strong>for</strong> natural ln baseline tibia Pb 0.082 (0.029,<br />

0.135) compared to 0.005 (!0.005, 0.015) <strong>for</strong> nondiabetics.<br />

Significant interaction <strong>of</strong> tibia Pb with hypertensive status<br />

in predicting annual change in serum creatinine.<br />

∃ (95% CI) <strong>for</strong> natural ln baseline tibia Pb 0.023 (0.003,<br />

0.019) compared to 0.0004 (!0.001, 0.002) <strong>for</strong> nonhypertensives.<br />

Follow-up serum creatinine was also modeled separately<br />

in longitudinal analyses; diabetes modified the association<br />

between baseline tibia Pb and follow-up serum creatinine.


AX6-74<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Wu et al. (2003a)<br />

Boston, MA<br />

1991-1995<br />

709 men enrolled in the Normative Aging Study.<br />

Serum creatinine<br />

1.2 mg/dL<br />

Calculated creatinine clearance<br />

71.3 mL/min<br />

Serum uric acid<br />

6.5 mg/dL<br />

Multiple linear regression, adjusting <strong>for</strong> age, body<br />

mass index, blood pressure or HTN (depending on<br />

model), and alcohol ingestion. Uric acid models also<br />

adjusted <strong>for</strong> serum creatinine, other outcome models<br />

adjusted <strong>for</strong> smoking status and analgesic medication<br />

use.<br />

Mean (SD) blood Pb<br />

6.2 (4.2) µg/dL<br />

Mean (SD) tibia Pb<br />

22 (13.4) µg/g bone mineral<br />

Mean (SD) patella Pb<br />

32.1 (19.5) µg/g bone mineral<br />

Significant inverse association between patella Pb and<br />

creatinine clearance.<br />

∃ = !0.069, SE not provided<br />

Borderline significant (p = 0.08) inverse association<br />

between tibia Pb and creatinine clearance. Borderline<br />

significant (p = 0.08) positive associations between tibia<br />

and patella Pb and uric acid. No Pb measure significantly<br />

associated with serum creatinine.<br />

ALAD gene polymorphism also assessed. 114<br />

participants had the ALAD2 variant allele (7 were<br />

homozygous). None <strong>of</strong> the three renal outcomes differed<br />

by genotype. Effect modification by genotype on the<br />

association between tibia Pb and serum creatinine was<br />

observed; the beta coefficient (and slope) was greater in<br />

the group with the variant allele (∃ = 0.002 [SE not<br />

provided]; p = 0.03).<br />

Effect modification <strong>of</strong> borderline significance (p < 0.1) on<br />

relations between <strong>of</strong> patella and tibia Pb with uric acid was<br />

observed; this was significant in participants whose patella<br />

Pb levels were above 15 μg/g bone mineral (∃ = 0.016 [SE<br />

not provided]; p = 0.04 ). Similar to the serum creatinine<br />

model, patella Pb was associated with higher uric acid in<br />

those with the variant allele. Genotype did not modify Pb<br />

associations in models <strong>of</strong> estimated creatinine clearance.


AX6-75<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Alfven et al. (2002)<br />

Sweden<br />

OSCAR Study<br />

Date not provided<br />

Akesson et al. (2005)<br />

Women’s Health in<br />

the Lund Area Study,<br />

1999-2000<br />

N = 479 men, 542 women. All resided near two<br />

battery plants, 117 participants were current or <strong>for</strong>mer<br />

workers from plants.<br />

Renal outcome = urinary α 1 microglobulin.<br />

Multiple linear regression.<br />

Age, smoking status, gender (by stratification),<br />

blood cadmium.<br />

N = 820 women<br />

Renal outcomes = GFR (estimated with cystatin C),<br />

estimated creatinine clearance, urinary NAG and α 1<br />

microglobulin.<br />

Multiple linear regression.<br />

Age, body mass index, diabetes, hypertension, and<br />

regular use <strong>of</strong> nephrotoxic drug, blood and urinary<br />

cadmium (in separate models), smoking status<br />

(by stratification).<br />

Mean blood Pb<br />

0.16 µmolg/L men<br />

0.11 µmolg/L women<br />

Mean blood Pb<br />

2.2 µg/dL<br />

Blood Pb not associated with urinary α 1 microglobulin<br />

(regression per<strong>for</strong>med separately in men and women).<br />

Blood Pb negatively associated with estimated GFR and<br />

creatinine clearance. No associations with NAG or α1<br />

microglobulin.<br />

∃ (95% CI) <strong>for</strong> association between blood Pb (µg/dL) and<br />

estimated creatinine clearance (mL/min) is !1.8<br />

(!3.0, !0.7).


AX6-76<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

De Burbure et al.<br />

(2003)<br />

France<br />

Study date not provided<br />

600 adults (399 exposed, 201 age and gender matched controls).<br />

400 children (200 exposed, 200 age and gender matched controls).<br />

Age ranged from 8.5 to 12.3 yrs.<br />

Exposure from residence near smelters.<br />

Exclusion criteria <strong>for</strong> children included obesity, diabetes, and puberty;<br />

<strong>for</strong> adults included pregnancy, cancer, diabetes, and kidney disease.<br />

Serum creatinine<br />

1.43 mg/dL (adult male controls)<br />

1.38 mg/dL (exposed adult males)<br />

1.33 mg/dL (adult female controls)<br />

1.26 mg/dL (exposed adult females)<br />

Urinary ∃2-microglobulin<br />

68.16 µg/g creatinine (adult male controls)<br />

76.29 µg/g creatinine (exposed adult males)<br />

63.79 µg/g creatinine (adult female controls)<br />

71.98 µg/g creatinine (exposed adult females)<br />

87.8 µg/g creatinine (boy controls)<br />

97.3 µg/g creatinine (exposed boys)<br />

88.2 µg/g creatinine (girl controls)<br />

94.8 µg/g creatinine (exposed girls)<br />

Urinary NAG<br />

1.12 IU/g creatinine (adult male controls)<br />

1.24 IU/g creatinine (exposed adult males)<br />

0.98 IU/g creatinine (adult female controls)<br />

1.28 IU/g creatinine (exposed adult females)<br />

2.29 IU/g creatinine (boy controls)<br />

1.70 IU/g creatinine (exposed boys)<br />

2.21 IU/g creatinine (girl controls)<br />

1.07 IU/g creatinine (exposed girls)<br />

Urinary RBP<br />

82.8 µg/g creatinine (adult male controls)<br />

85.8 µg/g creatinine (exposed adult males)<br />

83.42 µg/g creatinine (adult female controls)<br />

95.81 µg/g creatinine (exposed adult females)<br />

94 µg/g creatinine (boy controls) 99 µg/g creatinine (exposed boys)<br />

110 µg/g creatinine (girl controls) 109 µg/g creatinine (exposed girls)<br />

Renal outcome measures also included urinary total protein, albumin,<br />

transferrin, and brush border antigens.<br />

Multiple linear regression adjusting <strong>for</strong> age, sex, body mass index,<br />

area <strong>of</strong> residence, smoking, alcohol ingestion, mercury, cadmium and<br />

urinary creatinine level.<br />

Geometric mean blood<br />

Pb<br />

7.13 µg/dL (adult male<br />

controls)<br />

6.78 µg/dL (exposed<br />

adult males)<br />

4.17 µg/dL<br />

(adult female controls)<br />

5.25 µg/dL<br />

(exposed adult females)<br />

3.42 µg/dL (boy<br />

controls)<br />

4.22 µg/dL (exposed<br />

boys)<br />

2.74 µg/dL (girl<br />

controls)<br />

3.69 µg/dL (exposed<br />

girls)<br />

Adults<br />

Mean blood Pb level higher in exposed women but not<br />

men. None <strong>of</strong> the renal outcomes analyzed showed<br />

any significant difference between exposed and<br />

unexposed groups. After adjustment <strong>for</strong> covariates,<br />

blood Pb was not associated with any renal outcomes.<br />

Children<br />

Mean blood Pb levels higher in exposed. The highest<br />

geometric mean blood cadmium was 0.52 µg/L. None<br />

<strong>of</strong> the renal outcomes were significantly higher in<br />

exposed. After adjustment <strong>for</strong> covariates, blood Pb<br />

was not associated with any renal outcomes, however,<br />

blood cadmium was positively associated with NAG.<br />

This association was present in both control and<br />

exposed areas.<br />

Participants with extremes <strong>of</strong> urinary creatinine<br />

excluded from data analyses. As a result, number <strong>of</strong><br />

subjects in data tables substantially less than in study.


AX6-77<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Factor-Litvak et al.<br />

(1993)<br />

Kosovo, Yugoslavia<br />

1985-1986<br />

Staessen et al. (1990)<br />

London, England<br />

Study date not<br />

provided<br />

1447 Yugoslavian women in prospective study <strong>of</strong><br />

environmental Pb exposure and pregnancy.<br />

Exposure from Kosovska Mitrovica with a Pb smelter,<br />

refinery, and battery plant. Controls from Pristina, 25<br />

miles away.<br />

Renal outcome = Proteinuria assessed with a dipstick.<br />

Exclusionary criteria included HTN (n = 37 excluded,<br />

similar blood Pb levels to remaining participants).<br />

Multiple logistic regression adjusting <strong>for</strong> age (linear<br />

and quadratic), height (linear and quadratic), cigarette<br />

smoking, gestational age (linear and quadratic), daily<br />

milk consumption, number <strong>of</strong> previous live births, avg<br />

weekly meat consumption, hemoglobin level and<br />

ethnic group.<br />

531 London civil servants (398 male, 133 female).<br />

Exclusionary criteria = occupational exposure to<br />

heavy metals.<br />

Serum creatinine<br />

1.10 mg/dL (men)<br />

0.88 mg/dL (women)<br />

Mean blood Pb<br />

17.1 µg/dL (582 exposed)<br />

5.1 µg/dL (865 controls)<br />

Mean blood Pb<br />

12.4 µg/dL (men)<br />

10.2 µg/dL (women)<br />

Proteinuria (negative, trace, or ∃1+)<br />

Exposed = 16.2% negative, 74.1% trace and 9.7% with<br />

∃1+ proteinuria. Controls = 32.4% negative, 60.6% trace<br />

and 7.1% with ∃1+ proteinuria. Authors attributed overall<br />

high proportion <strong>of</strong> proteinuria to pregnancy.<br />

Higher blood Pb associated with increased odds ratio <strong>for</strong><br />

trace and ∃1+ proteinuria.<br />

Comparing women in upper 10th percentile <strong>of</strong> exposure to<br />

lower 10th percentile <strong>of</strong> exposure, adjusted odds ratios<br />

(95% CI) <strong>for</strong> trace and ∃1+ proteinuria was 2.3 (1.3, 4.1)<br />

and 4.5 (1.5, 13.6), respectively.<br />

Limitations = limited renal outcomes assessed.<br />

After removal <strong>of</strong> 2 outliers, the study found no significant<br />

correlation between serum creatinine and log blood Pb in<br />

men.<br />

No correlation between serum creatinine and log blood Pb<br />

in women.<br />

Limitations = lack <strong>of</strong> adjustment in data analysis, limited<br />

Pb dose and renal outcome assessment, loss <strong>of</strong> power by<br />

analyzing gender in separate models.


AX6-78<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Staessen et al. (1992)<br />

Belgium<br />

1985-1989<br />

Blood Pb levels were measured in 1981 adult subjects<br />

(965 males, 1016 females) enrolled in the Cadmibel<br />

study <strong>of</strong> general Belgian population in four cadmium<br />

polluted and unpolluted areas.<br />

Inclusion criteria included age ∃20 yrs and residence<br />

in one <strong>of</strong> four study areas <strong>for</strong> ∃8 yrs. Participants<br />

were randomly selected from the study areas;<br />

participation rates were 78% in the two rural areas but<br />

only 39% in the urban areas (one area from each<br />

category was known to be cadmium polluted).<br />

Measured creatinine clearance<br />

99 mL/min (males)<br />

80 mL/min (females)<br />

Calculated creatinine clearance<br />

80 mL/min (males)<br />

69 mL/min (females)<br />

Multiple linear regression.<br />

Covariates assessed included age, age squared, gender<br />

(by stratifying), body mass index, blood pressure,<br />

ferritin level, smoking status, alcohol ingestion, rural<br />

vs. urban residence, analgesic and diuretic use, blood<br />

and urinary cadmium, diabetes, occupational exposure<br />

to heavy metals, and gamma glutamyl transpeptidase.<br />

Blood Pb<br />

11.4 µg/dL (males)<br />

7.5 µg/dL (females)<br />

Zinc protoporphyrin also<br />

assessed.<br />

After adjustment, log trans<strong>for</strong>med blood Pb negatively<br />

associated with measured creatinine clearance.<br />

∃ coefficient (95% CI)<br />

!9.5 (!0.9, !18.1) males<br />

!12.6 (!5.0, !20.3) females<br />

A 10 fold increase in blood Pb associated with a decrease<br />

in creatinine clearance <strong>of</strong> 10 and 13 mL/min in men and<br />

women, respectively.<br />

Log trans<strong>for</strong>med blood Pb also negatively associated with<br />

calculated creatinine clearance.<br />

∃ coefficient (95% CI)<br />

!13.1 (!5.3, !20.9) males<br />

!30.1 (!23.4, !36.8) females<br />

Log trans<strong>for</strong>med zinc protoporphyrin negatively<br />

associated with measured and calculated creatinine<br />

clearances and positively associated with serum ∃2-<br />

microglobulin in both sexes and with serum creatinine in<br />

men.<br />

Blood Pb positively associated with serum ∃ 2microglobulin<br />

in men.


AX6-79<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia<br />

Lin et al. (1993)<br />

Taiwan<br />

Study date not<br />

provided<br />

Satarug et al. (2004)<br />

Bangkok, Thailand<br />

Study date not<br />

provided<br />

123 adults living near a Pb battery factory <strong>for</strong> more<br />

than 10 yrs.<br />

Divided into 3 groups by proximity to the factory.<br />

Group 1 ≤500 m (n = 49)<br />

Group 2 1000-1500 m (n = 47)<br />

Group 3 farther away (n = 27)<br />

Exclusionary criteria included history <strong>of</strong> exposure to<br />

nephrotoxicants and nephrotoxicant medications, such<br />

as NSAIDs.<br />

24 h urinary NAG excretion<br />

3.3 U/day (Group 1)<br />

2.4 U/day (Group 3)<br />

Multiple linear regression with adjustment <strong>for</strong> age.<br />

118 Thai adults (53 men, 65 women).<br />

Renal outcome measures noted below, also include<br />

BUN and total urinary protein.<br />

Serum creatinine<br />

0.94 mg/dL (males)<br />

0.66 mg/dL (females)<br />

Urinary NAG<br />

4.4 U/g creatinine (males)<br />

4.6 U/g creatinine (females)<br />

Urinary ∃ 2-microglobulin<br />

51 µg/g creatinine (males)<br />

29 µg/g creatinine (females)<br />

Mean blood Pb<br />

16.6 µg/dL (Group 1)<br />

13.5 µg/dL (Group 2)<br />

7.9 µg/dL (Group 3)<br />

EDTA diagnostic chelation<br />

(done in Group 1)<br />

126.1 µg/24 hrs<br />

Mean “serum” Pb<br />

0.42 µg/dL (males) 0.3 µg/dL<br />

(females)<br />

Note – cannot determine from<br />

article if actually serum Pb<br />

(much less commonly used) or<br />

blood Pb.<br />

Mean urinary Pb<br />

1.3 µg/g creatinine (males)<br />

2.4 µg/g creatinine<br />

(females)<br />

Urinary cadmium also<br />

assessed.<br />

Significantly higher prevalence <strong>of</strong> abnormal urinary NAG<br />

found in the exposed group 1 compared to the control group 3<br />

(55.6% compared to 11.1%; p < 0.001). However, mean<br />

NAG not significantly higher in Group 1.<br />

In all 45 participants in whom both measures were obtained,<br />

EDTA chelatable Pb was not correlated with urinary NAG<br />

excretion. However, a significant correlation between EDTA<br />

chelatable Pb #200 µg/24 hrs and urinary NAG excretion was<br />

observed in the 39 participants in this group. Further<br />

evaluation with multiple linear regression, adjusting <strong>for</strong> age,<br />

revealed a ∃ = 0.034 (95% CI: 0.009, 0.059); p = 0.01.<br />

No correlation noted between blood Pb level and urinary<br />

NAG.<br />

Limitations = small sample size, plots indicate potential <strong>for</strong><br />

influential outliers.<br />

In men, urinary Pb excretion correlated only with urinary<br />

protein at borderline significance (r = 0.22, p < 0.06).<br />

In women, urinary Pb excretion correlated with urinary NAG<br />

(r = 0.5, p < 0.001), protein (r = 0.31, p = 0.01) and<br />

∃ 2-microglobulin (r = 0.36, p = 0.002) excretion.<br />

After adjustment <strong>for</strong> urinary cadmium, only association<br />

between urinary Pb and NAG remained significant.<br />

Three urinary renal biomarkers correlated with urinary<br />

cadmium, although only at borderline significance (p = 0.06)<br />

<strong>for</strong> ∃2-microglobulin.<br />

Limitations = small sample size, Pb dose assessment since<br />

only urine Pb used in renal analyses, limited data analysis.


AX6-80<br />

Table AX6-4.1 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the General Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Satarug et al. (2004)<br />

Bangkok, Thailand<br />

Study date not<br />

provided<br />

Middle East<br />

Mortada et al. (2004)<br />

Egypt<br />

Study date not<br />

provided<br />

96 Thai men.<br />

Subjects subdivided into nonsmokers (n = 53), current<br />

smokers (n = 27), and ex-smokers (n = 16).<br />

Renal outcome measures noted below, also include<br />

BUN and total urinary protein.<br />

Serum creatinine<br />

0.94 mg/dL (nonsmokers)<br />

0.93 mg/dL (smokers)<br />

0.96 mg/dL (ex-smokers)<br />

Urinary NAG<br />

4.4 U/g creatinine (nonsmokers)<br />

4.2 U/g creatinine (smokers)<br />

3.8 U/g creatinine (ex-smokers)<br />

Urinary ∃2-microglobulin<br />

51 µg/g creatinine (nonsmokers)<br />

95 µg/g creatinine (smokers)<br />

98 µg/g creatinine (ex-smokers)<br />

68 Egyptian men (35 smokers, 33).<br />

Renal outcomes included serum creatinine, BUN, and<br />

∃ 2- microglobulin and urinary albumin, NAG, ∃ 2microglobulin,<br />

alkaline phosphatase, and γ-glutamyl<br />

transferase.<br />

Mean “serum” Pb<br />

0.42 µg/dL (nonsmokers)<br />

0.9 µg/dL (smokers)<br />

0.61 µg/dL (ex-smokers)<br />

Mean urinary Pb<br />

1.3 µg/g creatinine<br />

(nonsmokers)<br />

1.4 µg/g creatinine (smokers)<br />

1.4 µg/g creatinine (exsmokers)<br />

Urinary cadmium<br />

also assessed.<br />

Mean blood Pb<br />

14.4 µg/dL (smokers)<br />

10.2 µg/dL (nonsmokers)<br />

Pb also measured in urine,<br />

hair, and nails.<br />

Also measured cadmium, and<br />

mercury.<br />

Urinary Pb correlated with urinary protein (r = 0.49,<br />

p < 0.01) in smokers and at borderline significance<br />

(r = 0.22; p = 0.06) in never smokers. Also correlated<br />

with ∃2-microglobulin in ex-smokers at borderline<br />

significance (r = 0.39; p = 0.06).<br />

Urinary cadmium correlated with urinary NAG in current<br />

and never smokers and at borderline significance<br />

(p = 0.07) in ex-smokers. Also correlated with urinary<br />

protein and ∃2-microglobulin in current smokers and, at<br />

borderline significance, in never smokers.<br />

Limitations = small sample size, Pb dose assessment since<br />

only urine Pb used in renal analyses, limited data analysis.<br />

Blood and hair Pb levels significantly higher in smokers as<br />

compared to nonsmokers.<br />

No significant differences in renal outcome measures by<br />

smoking status. No correlation between exposure indices<br />

and renal outcome measures.<br />

Limitations: small sample size, data analysis – no<br />

adjustment.


AX6-81<br />

Table AX6-4.2. Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Smith et al. (1995)<br />

U.S.<br />

Study date not<br />

provided<br />

Europe<br />

Bergdahl et al. (1997)<br />

Sweden<br />

Study date not<br />

provided<br />

691 construction workers.<br />

96 participants with the ALAD2 allele.<br />

89 Pb workers; 7 had the ALAD2 allele.<br />

34 controls; 10 had the ALAD2 allele.<br />

Mean blood Pb<br />

7.8 µg/dL (ALAD11)<br />

7.7 µg/dL (ALAD12 or 22)<br />

Median blood Pb<br />

31.1 µg/dL in Pb workers<br />

with ALAD11<br />

28.8 µg/dL in Pb workers<br />

with ALAD12 or 22<br />

3.7 µg/dL in control workers<br />

with ALAD11<br />

3.7 µg/dL in control workers<br />

with ALAD12 or 22<br />

Higher mean BUN (p = 0.03) in participants with the<br />

ALAD2 allele compared to those with the ALAD11<br />

genotype. However, after adjustment <strong>for</strong> age, alcohol<br />

ingestion, and blood Pb, the association was no longer<br />

significant. Effect modification was not evaluated.<br />

Higher crude mean serum creatinine (p = 0.11) in<br />

participants with the ALAD2 allele compared to those<br />

with the ALAD11 genotype. Adjusted data not presented.


AX6-82<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

C35 μg/dL and exposure >1 yr were required<br />

in exposed workers. Participants with renal disease, renal<br />

risk factors, such as diabetes or regular analgesic medication<br />

use, or urinary cadmium >2 μg/g creatinine, were excluded.<br />

Multiple linear regression; adjusted <strong>for</strong> urinary creatinine<br />

and, in some cases, BMI.<br />

Serum creatinine<br />

1.02 mg/dL (workers)<br />

1.03 mg/dL (controls)<br />

Battery <strong>of</strong> more than 20 renal biomarkers obtained<br />

including:<br />

RBP<br />

68 µg/L (workers)<br />

64 µg/L (controls)<br />

NAG<br />

1.56 U/L (workers)<br />

1.21 U/L (controls)<br />

Mean blood Pb<br />

48.0 µg/dL (workers)<br />

16.7 µg/dL (controls)<br />

Mean duration <strong>of</strong> Pb<br />

exposure = 14 yrs<br />

Urinary cadmium also<br />

measured as potential<br />

confounder.<br />

Serum creatinine was not increased in Pb workers<br />

compared to controls; associations between Pb dose and<br />

serum creatinine, if assessed, were not specifically<br />

reported.<br />

In all 82, blood Pb:<br />

-associated with thromboxane B2 (∃ = 0.36, p < 0.01).<br />

-negatively associated with 6-keto-prostaglandin F 1 alpha<br />

(∃ = !0.179, p < 0.01).<br />

Zinc protoporphyrin positively associated with sialic acid<br />

excretion.<br />

NAG increased in Pb workers but associated with urinary<br />

cadmium.<br />

Limitations = sample size, potential <strong>for</strong> healthy worker<br />

bias, limited statistical analysis.


AX6-83<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Coratelli et al. (1988)<br />

Study location and<br />

date not provided;<br />

authors from Italy<br />

Fels et al. (1994)<br />

Study location and<br />

date not provided<br />

Garçon et al. (2004)<br />

France<br />

Study date not<br />

provided<br />

20 Pb battery factory workers.<br />

20 controls.<br />

12 mo longitudinal study.<br />

Renal outcomes = urinary alanine aminopeptidase, NAG<br />

and lysozyme.<br />

81 male Pb workers; 45 age matched controls.<br />

Extensive exclusionary criteria.<br />

Renal outcomes<br />

Serum creatinine<br />

Glomerular markers = 6-keto-prostaglandin F 1 alpha,<br />

thromboxane B 2, and fibronectin.<br />

Proximal tubular markers = brush border antigens (BBA,<br />

BB50, HF5) and intestinal alkaline phosphatase.<br />

Distal nephron markers = prostaglandin E2, prostaglandin<br />

F 2 alpha.<br />

35 male nonferrous metal smelter workers.<br />

Renal outcomes = α1-microprotein, ∃ 2-microglobulin,<br />

retinol binding protein, α and π glutathione S transferases<br />

(GST).<br />

Oxidative stress markers also measured.<br />

All variables log trans<strong>for</strong>med.<br />

Initial mean blood Pb<br />

47.9 µg/dL (workers)<br />

23.6 µg/dL (controls)<br />

Median blood Pb<br />

42.1 µg/dL (workers)<br />

7.0 µg/dL (controls)<br />

Mean blood Pb<br />

39.6 µg/dL<br />

Mean blood cadmium<br />

5.8 µg/L<br />

Mean urine cadmium<br />

4.7 µg/g creatinine<br />

NAG and lysozyme higher in exposed compared to<br />

controls throughout study. A statistically significant<br />

decline in urinary NAG was noted in association with a<br />

one mo period <strong>of</strong> decreased occupational exposure in the<br />

Pb workers. NAG correlated with time <strong>of</strong> exposure<br />

(nonlinear) but not blood Pb. Clinical renal function<br />

measures were not studied.<br />

Serum creatinine similar in exposed compared to controls.<br />

Medians <strong>of</strong> several markers statistically greater in workers<br />

compared to controls. After adjustment <strong>for</strong> age and<br />

erythrocyte protoporphyrin, several renal marker outcomes<br />

showed “some relation” to blood Pb. The table <strong>of</strong> these<br />

data shows r and r 2 but not beta coefficients making the<br />

actual statistical method used unclear.<br />

Study limitations include lack <strong>of</strong> adjustment in statistical<br />

analysis, potential <strong>for</strong> healthy worker bias.<br />

Correlations between urine Pb and cadmium and the renal<br />

outcomes assessed (not blood Pb or cadmium).<br />

Significant positive correlations included:<br />

urine Pb and α GST (p < 0.01)<br />

urine cadmium and RBP (p < 0.05)<br />

Also, urine cadmium and 8-OHdG negatively correlated.<br />

Limitations = use <strong>of</strong> urine Pb, lack <strong>of</strong> adjustment <strong>for</strong> other<br />

covariates, sample size.<br />

Significant correlations between blood Pb and two<br />

markers <strong>of</strong> oxidative stress were observed along with a<br />

correlation between blood cadmium and one marker <strong>of</strong><br />

oxidative stress.


AX6-84<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Gennart et al. (1992)<br />

Study location and<br />

dates not provided;<br />

authors from Belgium<br />

98 Pb workers and 85 controls from initial group <strong>of</strong> 221.<br />

Renal outcomes = urinary retinol-binding protein, ∃-2<br />

microglobulin, albumin, NAG, and serum creatinine and<br />

∃-2 microglobulin and estimated creatinine clearance.<br />

Exclusionary criteria included lack <strong>of</strong> exposure to other<br />

metals or solvents, urinary cadmium 40 µg/dL (workers) and


AX6-85<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Gerhardsson et al.<br />

(1992)<br />

Sweden<br />

Study date not<br />

provided<br />

70 current Pb smelter workers.<br />

30 retired Pb smelter workers.<br />

31 active and 10 retired truck assembly workers (controls).<br />

Renal outcomes = serum creatinine, urinary ∃-2<br />

microglobulin, NAG, and albumin, clearances <strong>of</strong><br />

creatinine, albumin, relative albumin, ∃-2 microglobulin<br />

and relative ∃-2 microglobulin.<br />

Blood Pb measured annually since 1950; time integrated<br />

blood Pb index = summation <strong>of</strong> annual blood Pb<br />

measurements.<br />

Median blood Pb<br />

31.9 µg/dL (current Pb workers)<br />

9.9 µg/dL (retired Pb workers)<br />

4.1 µg/dL (current control workers)<br />

3.5 µg/dL (retired control workers)<br />

Median time integrated blood Pb index<br />

369.9 µg/dL (current Pb workers)<br />

1496.1 µg/dL (retired Pb workers)<br />

Median calcaneus Pb<br />

48.6 µg/g bone mineral<br />

(current Pb workers)<br />

100.2 µg/g bone mineral<br />

(retired Pb workers)<br />

Median tibia Pb<br />

13.0 µg/g bone mineral<br />

(current Pb workers)<br />

39.3 µg/g bone mineral<br />

(retired Pb workers)<br />

3.4 µg/g bone mineral<br />

(current control workers)<br />

12.0 µg/g bone mineral<br />

(retired control workers)<br />

Creatinine clearance was higher in Pb workers;<br />

p-values not reported <strong>for</strong> this or other median<br />

values between Pb workers and controls.<br />

In current Pb workers, blood Pb was positively<br />

correlated with urinary ∃-2 microglobulin and time<br />

integrated blood Pb index was correlated with<br />

NAG (data not shown).<br />

Strengths include assessment <strong>of</strong> cumulative Pb,<br />

inclusion <strong>of</strong> <strong>for</strong>mer workers.<br />

Limitations = statistical analysis, lack <strong>of</strong> power<br />

by stratifying.


AX6-86<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Pergande et al. (1994)<br />

Study location and<br />

date not provided;<br />

research team is<br />

German<br />

Restek-Samaržija<br />

et al. (1996)<br />

Croatia<br />

Study date not<br />

provided<br />

Restek-Samaržija<br />

et al. (1997)<br />

Croatia<br />

Study date not<br />

provided<br />

82 male Pb workers.<br />

44 age-matched healthy male volunteers without known<br />

exposure to Pb and living “in areas distant from the<br />

exposed people.”<br />

Renal outcomes = serum creatinine and ∃ 2 microglobulin,<br />

urinary albumin and 14 other early biological effect<br />

markers.<br />

Exclusion criteria included prescription medication use<br />

and many diseases; 11 workers and 3 controls excluded.<br />

74 patients treated between 1951 and 1989 <strong>for</strong> at least one<br />

episode <strong>of</strong> Pb poisoning (53 occupational, 23<br />

environmental).<br />

Renal outcomes = measured creatinine clearance<br />

(collection time not specified), GFR assessed with<br />

99m<br />

Tc-diethylenetriaminepenta-acetic acid (DTPA)<br />

clearance.<br />

38 patients with occupational Pb poisoning, 23<br />

occupationally exposed workers.<br />

Renal outcomes = serum creatinine, measured creatinine<br />

clearance (collection time not specified), hippuran renal<br />

flow.<br />

Mean blood Pb<br />

42.1 µg/dL (workers)<br />

7.0 µg/dL (controls)<br />

Erythrocyte protoporphyrin<br />

also measured.<br />

Mean blood Pb<br />

1.5 µmol/L (poisoned<br />

workers)<br />

1.6 µmol/L (workers)<br />

Serum creatinine and ∃2 microglobulin not increased in<br />

exposed compared to control participants; correlations<br />

with these outcomes not reported. Blood Pb and/or<br />

erythrocyte protoporphyrin correlated with 9 <strong>of</strong> the<br />

urinary renal outcomes.<br />

Study limitations include lack <strong>of</strong> adjustment in<br />

statistical analysis, potential <strong>for</strong> healthy worker bias,<br />

potential <strong>for</strong> differences between exposed and control<br />

groups.<br />

Number <strong>of</strong> past Pb poisonings negatively correlated<br />

with creatinine and DTPA clearances.<br />

Creatinine clearance significantly lower in poisoned<br />

group.


AX6-87<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Roels et al. (1994)<br />

Belgium<br />

Study date not<br />

provided<br />

76 Pb smelter workers (including 21 participants from<br />

Cardenas et al. [1993] [Dr. Roels, email communication])<br />

68 controls.<br />

All males.<br />

Matched <strong>for</strong> age, sex, socioeconomic status, residence, and<br />

workshift characteristics.<br />

Extensive exclusionary criteria included renal disease,<br />

analgesic abuse, chronic medication <strong>for</strong> gout, diabetes,<br />

occupational exposure to other nephrotoxicants, and prior<br />

EDTA chelation.<br />

Renal outcomes included serum creatinine and urea<br />

nitrogen, measured creatinine clearance, NAG, RBP,<br />

serum and urinary ∃2-microglobulin, as well as other renal<br />

early biological effect markers.<br />

Measured creatinine clearance<br />

121.3 mL/min/1.73 m 2 (workers)<br />

115.5 mL/min/1.73 m 2 (controls)<br />

Multiple linear regression, adjusted <strong>for</strong> age, urinary<br />

cadmium, hypertension, serum gamma-glutamyl<br />

transpeptidase, smoking, exposure status (exposed vs.<br />

control), and interaction between exposure variables and<br />

hypertension.<br />

Mean blood Pb<br />

43.0 µg/dL (workers)<br />

14.1 µg/dL (controls)<br />

Mean tibia Pb<br />

66 µg/g bone mineral<br />

(workers)<br />

21 µg/g bone mineral<br />

(controls)<br />

Urinary cadmium also<br />

measured.<br />

Creatinine clearance measured be<strong>for</strong>e and after an oral<br />

protein load to determine if eicosanoid changes in<br />

Cardenas et al. (1993) had clinical implications (Acute<br />

protein ingestion causes increased renal perfusion and<br />

transient hyperfiltration thought to be mediated by<br />

changes in vasodilator prostanoids. There<strong>for</strong>e, it was<br />

hypothesized that, if the changes noted in Cardenas<br />

et al. (1993) were clinically significant, the<br />

hyperfiltration response would be diminished in the Pb<br />

workers.).<br />

All participants had normal baseline creatinine<br />

clearances (>80 mL/min/1.73 m²). Both control and<br />

Pb-exposed workers showed a similar increment in<br />

creatinine clearance after protein load.<br />

However, mean creatinine clearance was statistically<br />

higher in Pb workers compared to controls. Log tibia<br />

Pb was positively correlated with log measured<br />

creatinine clearance in the combined group<br />

(∃ = 0.0319, SE not provided).<br />

This was unexpected as the change in eicosanoids<br />

found in the initial study would not seem to result in<br />

vasodilatation with increased GFR. Un<strong>for</strong>tunately, it<br />

was not possible to measure eicosanoid levels in the<br />

follow-up study. No other significant associations<br />

between Pb measures and renal outcomes were<br />

observed. Urinary cadmium associated with NAG.


AX6-88<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Verschoor et al.<br />

(1987)<br />

Study location and<br />

date not provided;<br />

authors from The<br />

Netherlands<br />

Latin and South America<br />

Cardozo dos Santos<br />

et al. (1994)<br />

Study location and<br />

date not provided;<br />

authors from Brazil<br />

155 Pb workers (Pb battery and plastic stabilizer).<br />

126 control industrial workers.<br />

Workers with renal disease, HTN, prescription<br />

medications excluded.<br />

Renal outcomes = BUN, serum creatinine, uric acid,<br />

∃2-microglobulin, and RBP, and urinary RBP, NAG,<br />

albumin, uric acid, ∃2-microglobulin, IgG, and total<br />

protein. Urine protein electrophoresis per<strong>for</strong>med on subset<br />

(n = 25).<br />

Cadmium in blood and, in a subset <strong>of</strong> exposed workers, in<br />

urine was also assessed due to this exposure in one plant<br />

each from which Pb exposed and control workers were<br />

drawn.<br />

166 Pb battery workers.<br />

60 control workers.<br />

Renal outcomes = serum creatinine, NAG, urine albumin,<br />

and total urinary protein, γ-glutamyl-transpeptidase,<br />

alanine-aminopeptidase.<br />

Mean blood Pb<br />

47.5 µg/dL (workers)<br />

8.3 µg/dL (controls)<br />

Zinc protoporphyrin<br />

also used as Pb dose measure.<br />

Median blood Pb<br />

36.8 µg/dL (workers)<br />

11.6 µg/dL (controls)<br />

Mean renal outcomes in all participants shown by<br />

categorical Pb levels. NAG and RBP higher at blood<br />

Pb levels >21 µg/dL compared to those below this<br />

level (statistical significance not reported). Serum ∃2microglobulin<br />

and urinary total protein lower at blood<br />

Pb levels >21 µg/dL compared to those below this<br />

level (again, statistical significance not reported).<br />

In simple linear regression models <strong>of</strong> log trans<strong>for</strong>med<br />

urinary total protein, urinary RBP, NAG and serum ∃2microglobulin,<br />

higher log trans<strong>for</strong>med blood Pb was<br />

significantly associated with lower serum ∃2microglobulin<br />

and higher RBP and NAG.<br />

A matched pair analysis <strong>of</strong> 55 pairs matched <strong>for</strong> age<br />

within 5 yrs, smoking, socioeconomic status, and<br />

duration <strong>of</strong> employment found no differences in renal<br />

outcomes between exposed and controls.<br />

Limitations = lack <strong>of</strong> adjustment, potential <strong>for</strong> healthy<br />

worker bias, occupational cadmium exposure<br />

(including in controls) not adequately adjusted.<br />

Significant results.<br />

Median NAG higher in exposed group (p < 0.001).<br />

Blood Pb level and duration <strong>of</strong> exposure correlated<br />

with NAG in combined group (Spearman’s correlation<br />

coefficients = 0.32 and 0.22, respectively, p < 0.001 <strong>for</strong><br />

both).<br />

No results mentioned <strong>for</strong> serum creatinine.<br />

Limitations = statistical analysis (no regression <strong>for</strong><br />

renal outcomes).


AX6-89<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Latin and South America (cont’d)<br />

Pinto de Almeida<br />

et al. (1987)<br />

Northeast Brazil<br />

Study date not<br />

provided<br />

Australia<br />

Pollock and Ibels<br />

(1988)<br />

Harbor Bridge<br />

workers in Sydney,<br />

Australia<br />

Study date not<br />

provided<br />

52 primary Pb smelter workers (had to have worked ≥ 5<br />

yrs on production line).<br />

44 control paper mill workers in same city.<br />

All males.<br />

Renal outcomes = BUN, serum creatinine, uric acid,<br />

proteinuria, creatinine clearance.<br />

Only 2 participants excluded <strong>for</strong> medical reasons.<br />

38 bridge workers.<br />

Twenty-four h urine Pb excretion following 1 g <strong>of</strong> EDTA.<br />

Renal outcomes = serum creatinine, creatinine clearance,<br />

and 24 h urine protein excretion.<br />

Mean blood Pb<br />

64.1 µg/dL (workers)<br />

25.5 µg/dL (controls)<br />

Also measured zinc<br />

protoporphyrin and deltaaminolevulinic<br />

acid<br />

Mean (range) blood Pb<br />

34.8 (21.8 to 56.2) µg/dL (Pb<br />

intoxication)<br />

19.9 (9.5 to 26.1) µg/dL<br />

(nontoxic)<br />

EDTA chelatable Pb range<br />

443 to 2366 µg/24 hrs (Pb<br />

intoxication)<br />

131 to 402 µg/24 hrs<br />

(nontoxic)<br />

Mean serum creatinine and uric acid higher in exposed<br />

than controls (1.23 vs. 1.1 mg/dL; p < 0.05 and 6.6 vs.<br />

4.7 mg/dL; p < 0.001, respectively).<br />

Serum creatinine ∃1.5 mg/dL present in 32.7% Pb<br />

workers compared to only 2.3% controls.<br />

Serum creatinine correlated with duration <strong>of</strong><br />

employment.<br />

Limitations = data analysis including lack <strong>of</strong><br />

adjustment, several outcomes not analyzed.<br />

No significant differences in renal outcomes by Pb<br />

exposure group. Two workers in high exposure group<br />

had evidence <strong>of</strong> Pb nephropathy.


AX6-90<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Chia et al. (1994b)<br />

Study location not<br />

provided; authors<br />

from Singapore<br />

1982-1992 (blood Pb<br />

measurements<br />

obtained every 6 mos<br />

over this time)<br />

Chia et al. (1994c)<br />

Singapore<br />

Study location not<br />

provided; authors<br />

from Singapore<br />

1982-1992 (blood Pb<br />

measurements<br />

obtained every 6 mos<br />

over this time)<br />

128 Pb workers.<br />

152 control workers without Pb or cadmium exposure.<br />

Renal outcomes = total NAG, NAG-B isoenzyme<br />

(released with lysosomal breakdown assoc with cell<br />

membranes, thought to indicate proximal tubular cell<br />

toxicity), NAG-A (released by exocytosis).<br />

Cross-sectional outcomes but longitudinal exposure data.<br />

63 Pb workers <strong>of</strong> >6 mos work duration (median = 3 yrs).<br />

91 Pb workers <strong>of</strong> 40, 50, and 60 µg/dL.<br />

NAG not different in exposed compared to control<br />

workers.<br />

After adjustment <strong>for</strong> race, recent change in blood Pb<br />

was significantly associated with all NAG outcomes<br />

(standardized partial regression coefficients ranged<br />

from 0.31 <strong>for</strong> NAG-A to 0.64 <strong>for</strong> total NAG; neither<br />

SE nor CI provided).<br />

In contrast, current blood Pb was inversely associated<br />

with NAG-A and NAG-B separately but, oddly, not<br />

with total NAG. Authors do not comment on these<br />

inconsistencies.<br />

NAG not associated with cumulative Pb dose.<br />

Strengths = longitudinal exposure data.<br />

Limitations = data analysis clarity and adjustment.<br />

Urinary BB-50 higher in exposed compared to recent<br />

hire “control” workers. Time integrated blood Pb,<br />

number <strong>of</strong> times blood Pb >40 µg/dL, and relative<br />

change in recent blood Pb were associated with<br />

urinary BB-50.<br />

Strengths = longitudinal exposure data.<br />

Limitations = data analysis content (Pb dose means not<br />

reported), clarity and adjustment.


AX6-91<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Chia et al. (1995a)<br />

Study location not<br />

provided; authors<br />

from Singapore<br />

1982-1993 (blood Pb<br />

measurements<br />

obtained every 6 mos<br />

over this time)<br />

Chia et al. (1995b)<br />

Study location not<br />

provided; authors<br />

from Singapore<br />

1982-1993 (blood Pb<br />

measurements<br />

obtained every 6 mos<br />

over this time)<br />

137 Pb stabilizer workers.<br />

Control group <strong>of</strong> 153 postal workers (older than Pb<br />

workers).<br />

Renal outcomes = serum creatinine, four h creatinine<br />

clearance, serum ∃-2 microglobulin, serum α-1<br />

microglobulin, urine albumin.<br />

Longitudinal blood Pb data (mean <strong>of</strong> 4.5 measurements<br />

per Pb worker).<br />

128 Pb stabilizer factory workers.<br />

93 unexposed control subjects (evaluated at preemployment<br />

examination; all quit within 1 mo <strong>of</strong> hire).<br />

Blood and urinary cadmium also measured on random<br />

subset (40 controls and 31 Pb workers).<br />

Renal outcomes = serum ∃-2 microglobulin and urinary α-<br />

1 microglobulin, ∃-2 microglobulin, albumin, RBP.<br />

Pb dose measures<br />

(means or medians not stated)<br />

Most recent blood Pb, time<br />

integrated blood Pb index,<br />

relative % change in recent<br />

blood Pb, absolute change in<br />

recent blood Pb, number <strong>of</strong><br />

times blood Pb level >40, 50,<br />

and 60 µg/dL.<br />

Mean recent blood Pb<br />

32.6 µg/dL (workers)<br />

9.0 µg/dL (controls)<br />

Mean time integrated blood<br />

Pb index<br />

119.9 µg/dL Η yr (workers)<br />

0.05 µg/dL Η yr (controls)<br />

Mean relative change in<br />

recent blood Pb<br />

28.2 % (workers)<br />

Mean absolute change in<br />

recent blood Pb<br />

6.4 µg/dL/yr (workers)<br />

Number <strong>of</strong> times blood Pb<br />

level >40, 50 and 60 µg/dL<br />

In analysis <strong>of</strong> covariance modeling, adjusted <strong>for</strong> age and race,<br />

mean serum α-1 microglobulin and urine albumin were<br />

significantly higher in control compared to Pb workers.<br />

Serum ∃-2 microglobulin was significantly higher in Pb<br />

workers ≥30 yrs <strong>of</strong> age.<br />

After adjustment <strong>for</strong> age, race, and smoking, prevalence rates<br />

<strong>for</strong> abnormal values <strong>of</strong> serum creatinine and ∃-2<br />

microglobulin were higher in the highest category <strong>of</strong> time<br />

integrated blood Pb index in workers ∃30 yrs <strong>of</strong> age<br />

(PRR = 3.8 [95% CI: 1.1, 13.3] and 10.3 [95% CI: 3.9,<br />

26.9], respectively).<br />

Strengths = longitudinal exposure data.<br />

Limitations = data analysis content (Pb dose means not<br />

reported), clarity and adjustment.<br />

Only urinary α-1 microglobulin was significantly higher in Pb<br />

workers compared to controls.<br />

In multiple linear regression analysis, adjusted only <strong>for</strong><br />

ethnicity and smoking, at least one Pb measure was<br />

significantly associated with each <strong>of</strong> the five renal outcomes.<br />

Outcome Pb measure ∃ (95% CI)<br />

U α-1 MG cum. blood Pb 0.10 (0.06, 0.14)<br />

U α-1 MG # blood Pb >50 0.43 (0.04, 0.82)<br />

U ∃-2 MG cum. blood Pb 0.05 (0.01, 0.09)<br />

U RBP # blood Pb >50 0.35 (0.12, 0.59)<br />

S ∃-2 MG # blood Pb >60 0.47 (0.29, 0.65)<br />

U Alb # blood Pb >60 0.66 (0.13, 1.19)<br />

Cadmium dose measures reportedly not significant in these<br />

models (although power would have been reduced as<br />

cadmium measured only in a subset).<br />

Strengths = longitudinal exposure data.<br />

Limitations = data analysis clarity and adjustment. Overlap<br />

in populations between this study and earlier ones possible.


AX6-92<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Endo et al. (1990)<br />

Study location not<br />

provided; authors<br />

from Japan<br />

1987<br />

Endo et al. (1993)<br />

Study location and<br />

date not provided;<br />

authors from Japan<br />

39 male workers.<br />

7 female workers (none directly exposed to Pb).<br />

Secondary Pb refinery, mean job duration = 10.5 yrs<br />

Renal outcomes = BUN, serum creatinine and uric acid,<br />

urinary NAG, and tubular reabsorption <strong>of</strong> phosphate.<br />

99 male Pb workers.<br />

Renal outcomes = serum creatinine and serum and urine<br />

alpha-1-microglobulin.<br />

Mean blood Pb<br />

Ranged from 24.1 to<br />

67.6 µg/dL (males)<br />

19.6 µg/dL (females)<br />

Other Pb measures included<br />

urinary Pb, deltaaminolevulinic<br />

acid, and<br />

coproporphyrin.<br />

Median blood Pb<br />

Ranged from 7.9 µg/dL in<br />

category I consisting <strong>of</strong> 16<br />

<strong>of</strong>fice workers who did not<br />

work directly with Pb to<br />

76.2 µg/dL in 16 workers in<br />

the highest exposure group<br />

(category V).<br />

Significant correlations <strong>of</strong> blood Pb and delta-amino-levulinic<br />

acid with BUN and NAG were observed. The correlation<br />

between blood Pb and NAG was dependent on a small<br />

number <strong>of</strong> workers whose blood Pb levels were above<br />

80 µg/dL.<br />

Limitations include absence <strong>of</strong> adjustment in statistical<br />

analysis, small sample size.<br />

Median urinary alpha-1-microglobulin significantly higher in<br />

categories <strong>II</strong>I–V compared to the low exposure group <strong>of</strong><br />

<strong>of</strong>fice workers. This was also the only renal outcome to be<br />

significantly correlated with blood Pb (Spearman rank<br />

correlation).<br />

After alpha-1-microglobulin adjusted <strong>for</strong> age and blood Pb<br />

(by stratifying); few significant differences noted. However,<br />

analysis approach resulted in substantial loss <strong>of</strong> power.


AX6-93<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Hsiao et al. (2001)<br />

Taiwan, PR China<br />

1991-1998<br />

30 Pb battery workers.<br />

Mean serum creatinine at baseline<br />

~ 1.0 mg/dL (based on figure; exact values not provided)<br />

Longitudinal Analysis, 8 annual evaluations.<br />

Generalized estimating equations used to adjust <strong>for</strong><br />

autocorrelation in multiple datapoints from each<br />

participant.<br />

Adjusted <strong>for</strong> age, gender, and, in models <strong>of</strong> change in<br />

serum creatinine, creatinine at beginning <strong>of</strong> interval.<br />

Mean blood Pb at baseline<br />

~35 µg/dL (based on figure;<br />

exact values not provided)<br />

Mean duration <strong>of</strong> exposure<br />

at baseline<br />

13.1 yrs<br />

Cross-sectional<br />

higher blood Pb associated with lower concurrent<br />

serum creatinine.<br />

Longitudinal<br />

Change in blood Pb negatively associated with<br />

concurrent change in serum creatinine (p = 0.07).<br />

Blood Pb at the beginning <strong>of</strong> the interval not associated<br />

with change in serum creatinine in the following yr.<br />

Associations may represent Pb-related hyperfiltration.<br />

However, as noted by the authors, cumulative Pb dose<br />

may also be a factor. Mean blood Pb declined greatly<br />

just be<strong>for</strong>e renal data collection started. There<strong>for</strong>e, the<br />

inverse longitudinal associations could be due to<br />

persistently elevated cumulative dose (which was<br />

unmeasured but, as evidenced by the long half-life <strong>of</strong><br />

bone Pb, likely did not decline as much as blood Pb).<br />

However, authors did not model cumulative blood Pb<br />

or analyze effect modification by time period, age, or<br />

exposure duration to determine if these associations<br />

changed in a pattern consistent with hyperfiltration.<br />

The small sample size also limits conclusions that may<br />

be drawn from these results since a small number <strong>of</strong><br />

individuals may be overly influential.<br />

Strengths = longitudinal data.<br />

Limitations = data analysis content (Pb dose means not<br />

reported), clarity and adjustment.


AX6-94<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Huang et al. (1988)<br />

Beijing, China<br />

Study date not<br />

provided<br />

Jung et al. (1998)<br />

Korea<br />

Study date not<br />

provided<br />

Konishi, et al. (1994)<br />

Study location<br />

not provided;<br />

research team from<br />

Japan<br />

1991<br />

40 Pb workers (4 women).<br />

Control group not described.<br />

Renal outcomes = serum beta-2-microglobulin and urinary<br />

beta-2-microglobulin, total protein, IgG.<br />

75 randomly selected male Pb workers.<br />

64 male <strong>of</strong>fice workers (controls).<br />

Renal outcomes = BUN, serum creatinine, uric acid and<br />

urinary NAG, albumin, α1 microglobulin and ∃ 2<br />

microglobulin.<br />

99 male Pb workers, including 16 <strong>of</strong>fice workers to serve<br />

at controls.<br />

renal outcomes = fractional clearances <strong>of</strong> α1 microglobulin<br />

and ∃2 microglobulin (utilizing serum and urinary levels <strong>of</strong><br />

both biomarkers), BUN, serum creatinine, uric acid and<br />

urinary NAG.<br />

Geometric mean blood Pb<br />

40 µg/dL<br />

Mean blood Pb<br />

Means ranged from 24.3 to<br />

74.6 µg/dL (workers)<br />

7.9 µg/dL (controls)<br />

Other Pb measures included<br />

zinc protoporphyrin,<br />

δ-aminolevulinic acid activity<br />

and urinary Pb,<br />

coproporphyrin, and<br />

δ-aminolevulinic acid.<br />

Median blood Pb<br />

Range from 7.9 µg/dL in<br />

controls to 76.2 µg/dL in<br />

Category V<br />

Increased urinary ∃ 2 microglobulin in workers<br />

compared to controls.<br />

Multiple limitations including lack <strong>of</strong> in<strong>for</strong>mation on<br />

control group, data analysis.<br />

Blood Pb, zinc protoporphyrin, and urinary δaminolevulinic<br />

acid significantly correlated with BUN,<br />

NAG, and α1 microglobulin (appears to be combined<br />

group analysis).<br />

Limitation = statistical analysis - lack <strong>of</strong> adjustment.<br />

Urinary NAG, α1 microglobulin and fractional<br />

clearance <strong>of</strong> α 1 microglobulin increased with higher<br />

blood Pb category. Spearman rank correlation between<br />

fractional clearance <strong>of</strong> α 1 microglobulin and blood Pb<br />

was significant. This relation also assessed by multiple<br />

linear regression with adjustment <strong>for</strong> age; both<br />

independent variables were significantly associated<br />

with the fractional clearance <strong>of</strong> α1 microglobulin.<br />

Limitation = statistical analysis - lack <strong>of</strong> adjustment.


AX6-95<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Kumar and<br />

Krishnaswamy<br />

(1995)<br />

India<br />

Study date not<br />

provided<br />

Lim et al. (2001)<br />

Singapore<br />

1999<br />

Blood Pb levels every<br />

6 mos from 1982 to<br />

1999<br />

22 auto mechanics volunteers.<br />

27 male control workers (from Institute per<strong>for</strong>ming study).<br />

Renal outcomes = serum creatinine, 4 h creatinine<br />

clearance and urinary NAG and ∃-2 microglobulin.<br />

Renal disease, diabetes, HTN and occupational exposures<br />

excluded in controls, possibly excluded in workers.<br />

55 male Pb workers.<br />

Workers followed since 1982, many <strong>of</strong> same workers as in<br />

Chia et al. (1995b).<br />

Renal outcomes = 4 h creatinine clearance and urinary<br />

albumin, RBP, α1 microglobulin, ∃ 2 microglobulin, NAG,<br />

NAG-A, and NAG-B.<br />

Exclusionary criteria included diabetes, HTN, recent<br />

ingestion <strong>of</strong> analgesics, antipyretics, or antibiotics, and<br />

thalassemia; 24 participants <strong>of</strong> the original 80 were<br />

excluded as a result. One female also excluded.<br />

Blood Pb range<br />

24.3-62.4 µg/dL (exposed)<br />

19.4-30.6 µg/dL (controls)<br />

Mean current blood Pb<br />

24.1 µg/dL<br />

Cumulative blood index<br />

880.6 µg Η yrs/dL (geometric<br />

mean)<br />

Number <strong>of</strong> times blood Pb<br />

exceeded 40 µg/dL<br />

1.9 (geometric mean)<br />

Urinary NAG and ∃ 2 microglobulin levels were<br />

significantly higher in exposed compared to controls.<br />

However, only NAG was significantly correlated with<br />

blood Pb (r = 0.58, p < 0.01).<br />

Limitations = study size and lack <strong>of</strong> adjustment in<br />

analysis, values <strong>for</strong> 4 h creatinine clearance in<br />

abnormal low range in both exposed and controls.<br />

In separate models, after adjustment <strong>for</strong> age and<br />

smoking, higher categorical cumulative blood index<br />

and number <strong>of</strong> times blood Pb exceeded 40 µg/dL were<br />

associated with lower creatinine clearance (P < 0.001).<br />

After adjustment, higher number <strong>of</strong> times blood Pb<br />

exceeded 40 µg/dL was associated with higher urinary<br />

albumin, α 1 microglobulin, RBP, NAG, and NAG-B.<br />

Similarly, cumulative blood index was associated with<br />

higher urinary albumin, α 1 microglobulin, RBP, and ∃ 2<br />

microglobulin.<br />

No associations between recent blood Pb and any <strong>of</strong><br />

the renal outcomes was observed.<br />

Analysis <strong>of</strong> covariance was used to adjust <strong>for</strong> smoking<br />

and age.<br />

Limitation = statistical analysis - lack <strong>of</strong> adjustment,<br />

small sample size, potential <strong>for</strong> healthy worker bias.


AX6-96<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Ong et al. (1987)<br />

Singapore and Japan<br />

Study date not<br />

provided<br />

Wang et al. (2002b)<br />

Taiwan<br />

Study date not<br />

provided<br />

209 Pb workers (51 females).<br />

30 control workers from research staff.<br />

Renal outcomes = BUN, serum creatinine, calculated<br />

creatinine clearance, and urinary NAG.<br />

229 Pb battery workers, including 109 females.<br />

Renal outcomes = BUN, serum creatinine, serum<br />

uric acid.<br />

Multiple linear & logistic regression.<br />

Adjustment <strong>for</strong> age, gender, smoking, alcohol ingestion,<br />

milk ingestion.<br />

Mean blood Pb<br />

42.1 µg/dL (males)<br />

31.9 µg/dL (females)<br />

Urine Pb also measured.<br />

Mean blood Pb<br />

67.7 µg/dL (males)<br />

48.6 µg/dL (females)<br />

Blood Pb correlated with BUN(r = 0.16; p < 0.01),<br />

serum creatinine (r = 0.26; p < 0.001) and creatinine<br />

clearance (r = −0.16; p < 0.01). Blood Pb associated<br />

with NAG after adjustment <strong>for</strong> age (method not<br />

specified).<br />

Higher NAG in exposed compared to controls when<br />

stratified by categorical age.<br />

Strengths = sample size.<br />

Limitations = statistical analysis - lack <strong>of</strong> adjustment,<br />

urinary NAG not adjusted <strong>for</strong> urine dilution.<br />

∃ (95% CI) <strong>for</strong> blood Pb in model <strong>of</strong> BUN, after<br />

adjustment <strong>for</strong> Pb job duration/age = 0.062<br />

(0.042, 0.082).<br />

∃ (95% CI) <strong>for</strong> blood Pb in model <strong>of</strong> uric acid, after<br />

adjustment <strong>for</strong> gender and weight = 0.009<br />

(0.001, 0.016).<br />

Blood Pb not associated serum creatinine.


AX6-97<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Weaver et al. (2003a)<br />

South Korea<br />

1997-1999<br />

803 Pb workers including 164 females and 94 <strong>for</strong>mer Pb<br />

workers.<br />

Serum creatinine<br />

0.90 mg/dL<br />

Calculated creatinine clearance<br />

94.7 mL/min<br />

4-hr measured creatinine clearance<br />

114.7 mL/min<br />

RBP<br />

63.6 µg/g creatinine<br />

NAG<br />

215.3 μmol/h/g creatinine<br />

Multiple linear regression, adjusting <strong>for</strong> age, gender, BMI,<br />

work status (current vs. <strong>for</strong>mer worker), HTN or blood<br />

pressure (depending on model), and, <strong>for</strong> the EBE markers,<br />

alcohol ingestion and diabetes.<br />

42 associations modeled (7 Pb measures with 6 renal<br />

outcomes).<br />

Interaction models that assessed effect modification by<br />

age in tertiles in 24 associations (4 Pb exposure/dose<br />

measures with 6 renal outcomes).<br />

Mean blood Pb<br />

32.0 µg/dL<br />

Mean tibia Pb<br />

37.2 μg/g bone mineral<br />

Mean DMSA-chelatable Pb<br />

767.8 μg/g creatinine<br />

Pb exposure also assessed<br />

with job duration and three<br />

hematologic measures as<br />

surrogates <strong>for</strong> Pb dose<br />

(aminolevulinic acid in<br />

plasma, zinc protoporphyrin,<br />

and hemoglobin).<br />

Mean urinary cadmium<br />

measured in<br />

subset (n = 191)<br />

1.1 µg/g creatinine<br />

After adjustment, higher Pb measures associated with<br />

worse renal function in 9 <strong>of</strong> 42 models.<br />

Associations in the opposite direction (higher Pb<br />

measures associated with lower serum creatinine and<br />

higher creatinine clearances) in five models.<br />

Opposite direction (inverse) associations observed only<br />

in models <strong>of</strong> the clinical outcomes whereas the<br />

associations between higher Pb dose and worse renal<br />

function were predominantly among the biomarker<br />

models.<br />

In three <strong>of</strong> 16 clinical renal interaction models, positive<br />

associations between higher Pb measures and worse<br />

renal function in participants in the oldest age tertile<br />

were significantly different from associations in those<br />

in the youngest age tertile which were in the opposite<br />

direction.<br />

- This pattern was observed at borderline significance<br />

(p < 0.1) in 3 other models.<br />

- Pattern was not observed in the EBE marker models.<br />

Urinary cadmium associated with NAG.<br />

Authors concluded that occupational Pb exposure in<br />

the moderate dose range has an adverse effect on renal<br />

function. Inverse associations may represent<br />

hyperfiltration. Environmental cadmium may have an<br />

adverse impact, at least on NAG.


AX6-98<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Weaver et al. (2003b)<br />

Korea Pb workers<br />

1997-1999<br />

798 Pb workers with genotype in<strong>for</strong>mation in same<br />

population as in Weaver et al. (2003a).<br />

79 (9.9%) participants were heterozygous <strong>for</strong> the ALAD2<br />

allele (none was homozygous).<br />

89 (11.2%) had VDR genotype Bb or BB.<br />

Mean blood Pb<br />

31.7 µg/dL (ALAD11)<br />

34.2 µg/dL (ALAD12)<br />

31.6 µg/dL (VDR bb)<br />

34.8 µg/dL (VDR Bb or BB)<br />

Mean tibia Pb<br />

37.5 μg/g (ALAD11)<br />

31.4 µg/g (ALAD12)<br />

37.1 µg/g (VDR bb)<br />

38.1 µg/g (VDR Bb or BB)<br />

Data were analyzed to determine whether<br />

polymorphisms in the genes encoding δ-aminolevulinic<br />

acid dehydratase (ALAD), endothelial nitric oxide<br />

synthase (eNOS), and the vitamin D receptor (VDR)<br />

were associated with renal outcomes or modified<br />

relations <strong>of</strong> Pb exposure and dose measures with renal<br />

outcomes.<br />

After adjustment, participants with the ALAD2 allele<br />

had lower mean serum creatinine and higher calculated<br />

creatinine clearance. Effect modification by ALAD on<br />

associations between blood Pb and/or DMSAchelatable<br />

Pb and three <strong>of</strong> six renal outcomes was<br />

observed. Among those with the ALAD12 genotype,<br />

higher Pb measures were associated with lower BUN<br />

and serum creatinine and higher calculated creatinine<br />

clearance.<br />

No significant differences were seen in renal outcomes<br />

by VDR genotype nor was consistent effect<br />

modification observed.


AX6-99<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Weaver et al. (2005a)<br />

Korea<br />

1997-1999<br />

803 current and <strong>for</strong>mer Pb workers; 164 females.<br />

Serum Uric acid<br />

4.8 mg/dL<br />

Other renal outcomes as listed in Weaver et al., 2003a.<br />

Multiple linear regression.<br />

Interaction models that assessed effect modification by age<br />

in tertiles.<br />

Mean blood Pb<br />

32.0 µg/dL<br />

Mean tibia Pb<br />

37.2 (40.4) µg/g bone<br />

mineral<br />

Mean DMSAchelatable<br />

Pb<br />

767.8 µg/g creatinine<br />

Work to address whether one mechanism <strong>for</strong> Pb-related<br />

nephrotoxicity, even at current lower levels <strong>of</strong> Pb exposure, is via<br />

increasing serum uric acid. Assessed 1) whether Pb dose was<br />

associated with uric acid and 2) whether previously reported<br />

associations between Pb dose and renal outcomes (Weaver et al.,<br />

2003) were altered after adjustment <strong>for</strong> uric acid.<br />

After adjustment <strong>for</strong> age, gender, body mass index, and alcohol use,<br />

Pb biomarkers not associated with uric acid in all participants.<br />

However, in interaction models, both blood and tibia Pb were<br />

significantly associated in participants in the oldest age tertile<br />

(∃ = 0.0111 [95% CI: 0.003, 0.019] and 0.0036 [0.0001, 0.007] <strong>for</strong><br />

blood and tibia Pb, respectively). These models were further adjusted<br />

<strong>for</strong> blood pressure and renal function. Hypertension and renal<br />

dysfunction are known to increase uric acid. However, they are also<br />

risks associated with Pb exposure. There<strong>for</strong>e, adjustment <strong>for</strong> these<br />

variables in models <strong>of</strong> associations between Pb dose and uric acid<br />

likely results in over-control. On the other hand, since nonPb related<br />

factors contribute to both renal dysfunction and elevated blood<br />

pressure, lack <strong>of</strong> adjustment likely results in residual confounding.<br />

There<strong>for</strong>e, as expected, associations between Pb dose and uric acid<br />

decreased after adjustment <strong>for</strong> systolic blood pressure and serum<br />

creatinine, although blood Pb remained borderline significantly<br />

associated (∃ = 0.0071 [95% CI: !0.001, 0.015]). However, when the<br />

population was restricted to the oldest tertile <strong>of</strong> workers with serum<br />

creatinine greater than the median (0.86 mg/dL), likely the highest<br />

risk segment <strong>of</strong> the population, blood Pb remained significantly<br />

associated with uric acid even after adjustment <strong>for</strong> systolic blood<br />

pressure and serum creatinine (∃ = 0.0156).<br />

Next, in models <strong>of</strong> renal function in all workers, uric acid was<br />

significantly (p < 0.05) associated with all renal outcomes except<br />

NAG.<br />

In models in the oldest tertile <strong>of</strong> workers (266 workers, median age<br />

51.1 yrs, range 46.0 to 64.8 yrs), after adjustment <strong>for</strong> uric acid,<br />

associations between Pb dose and NAG were unchanged, but fewer<br />

<strong>of</strong> the previously significant (p # 0.05) associations noted between Pb<br />

dose and the clinical renal outcomes in Weaver et al. (2003a)<br />

remained significant.


AX6-100<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Weaver et al. (2005b)<br />

South Korea<br />

1999-2001<br />

652 Pb workers including 149 females and 200 <strong>for</strong>mer<br />

workers.<br />

Patella Pb measured in the third evaluation <strong>of</strong> the same<br />

study reported in Weaver et al. (2003a). Data collection<br />

per<strong>for</strong>med a mean <strong>of</strong> 2.2 yrs after collection <strong>of</strong> the data<br />

presented in Weaver et al. (2003a).<br />

Same renal outcomes as Weaver et al. (2003a).<br />

Serum creatinine<br />

0.87 mg/dL<br />

Calculated creatinine clearance<br />

97.0 mL/min<br />

Multiple linear regression, adjusting <strong>for</strong> age, gender, BMI,<br />

work status (current vs. <strong>for</strong>mer worker), HTN or blood<br />

pressure (depending on model), diabetes, smoking status,<br />

and, <strong>for</strong> the clinical measures, use <strong>of</strong> analgesics<br />

Interaction models assessed effect modification by age,<br />

dichotomized at the 67th percentile.<br />

Mean blood Pb<br />

30.9 µg/dL<br />

Mean tibia Pb<br />

33.6 µg/g bone mineral<br />

Mean patella Pb<br />

75.1 µg/g bone mineral<br />

Mean DMSA-chelatable Pb<br />

0.63 μg Pb/mg creatinine<br />

All 4 Pb measures were correlated (Spearman’s r = 0.51 –<br />

0.76).<br />

Patella, blood and DMSA-chelatable Pb levels positively<br />

associated with NAG.<br />

Higher DMSA-chelatable Pb associated with lower serum<br />

creatinine and higher calculated creatinine clearance.<br />

Interaction models<br />

All four Pb measures associated with higher NAG among<br />

participants in oldest age tertile.<br />

Higher blood, tibia, and patella Pb associated with higher<br />

serum creatinine among older participants.<br />

-Beta coefficients less in the Pb workers whose ages were in<br />

the younger two-thirds <strong>of</strong> the age range; difference between<br />

slopes in the two age groups was statistically significant only<br />

<strong>for</strong> association <strong>of</strong> blood Pb and serum creatinine.<br />

Inverse DMSA associations (higher DMSA-chelatable Pb<br />

associated with lower serum creatinine and higher calculated<br />

creatinine clearance) significant in younger workers.<br />

Patella Pb associations were consistent with those <strong>of</strong> blood and<br />

tibia Pb; DMSA-chelatable Pb associations unique.<br />

Authors hypothesized that similarities between patella, blood,<br />

and tibia Pb associations could be due, in part, to high<br />

correlations among the Pb biomarkers in this population.<br />

Despite similar high correlations, DMSA-chelatable Pb<br />

associations with serum creatinine and calculated creatinine<br />

clearance were unique. This biomarker is dependent on renal<br />

function and the collection time was only 4 h. There<strong>for</strong>e, the<br />

amount <strong>of</strong> Pb that is excreted in this relatively short time period<br />

after chelation may be influenced not only by bioavailable Pb<br />

burden, but also by high-normal as well as actual supranormal<br />

glomerular filtration which are more common in the younger<br />

workers.


AX6-101<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Weaver et al. (2005c)<br />

Korea<br />

1997-1999<br />

Ye et al. (2003)<br />

Chinese Pb workers<br />

Study date not<br />

provided<br />

798 current and <strong>for</strong>mer Pb workers.<br />

Same population as in Weaver et al. (2003a,b).<br />

216 Pb workers.<br />

Renal outcomes = urinary NAG and albumin.<br />

Geometric mean blood Pb<br />

37.8 μg/dL (n = 14 workers<br />

with the ALAD12 genotype)<br />

32.4 μg/dL (n = 212 workers<br />

with the ALAD11 genotype)<br />

31.9 µg/dL (VDR bb)<br />

41.7 µg/dL (in 20 participants<br />

with VDR Bb or BB)<br />

Data were analyzed to determine whether<br />

polymorphisms in the genes encoding δ-aminolevulinic<br />

acid dehydratase (ALAD), endothelial nitric oxide<br />

synthase (eNOS), and the vitamin D receptor (VDR)<br />

were associated with uric acid or modified relations <strong>of</strong><br />

Pb exposure and dose measures with uric acid.<br />

Uric acid not different by ALAD or VDR genotype.<br />

Among older workers (age ≥ median <strong>of</strong> 40.6 yrs),<br />

ALAD genotype modified associations between Pb<br />

dose and uric acid levels. Higher Pb dose was<br />

significantly associated with higher uric acid in<br />

workers with the ALAD11 genotype; associations were<br />

in the opposite direction in participants with the variant<br />

ALAD12 genotype.<br />

After adjustment <strong>for</strong> age, NAG was borderline higher<br />

in those with the ALAD variant allele whose blood Pb<br />

levels were ≥40 μg/dL (p = 0.06). In all Pb workers,<br />

after adjustment <strong>for</strong> age, gender, smoking, and alcohol<br />

ingestion, a statistically significant positive association<br />

between blood Pb and creatinine adjusted NAG was<br />

observed in the workers with the ALAD12 genotype<br />

but not in Pb workers with the ALAD11 genotype (the<br />

groups were analyzed separately rather than in an<br />

interaction model).<br />

No effect modification by VDR genotype on<br />

associations between blood Pb and urinary albumin<br />

and NAG observed (separate analysis reduced power).


AX6-102<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Middle East<br />

Al-Neamy et al.<br />

(2001)<br />

United Arab Emirates<br />

Feb-June, 1999<br />

Ehrlich et al. (1998)<br />

South Africa<br />

Study date not<br />

provided<br />

100 “industrial” workers exposed in a range <strong>of</strong> industries<br />

100 working controls.<br />

Matched <strong>for</strong> age, sex, and nationality.<br />

Renal outcomes = BUN, serum creatinine.<br />

382 Pb battery factory workers.<br />

Mean age = 41.2 yrs.<br />

All males.<br />

Multiple linear regression adjusted <strong>for</strong> age, weight, and<br />

height (Covariates assessed <strong>for</strong> inclusion also included<br />

smoking, alcohol ingestion, and diabetes).<br />

Clinical renal outcomes included serum creatinine, uric<br />

acid, and BUN.<br />

Mean serum creatinine<br />

1.13 mg/dL<br />

Renal early biological effect markers (NAG, RBP,<br />

intestinal alkaline phosphatase, tissue nonspecific alkaline<br />

phosphatase, Tamm-Horsfall glycoprotein, epidermal<br />

growth factor, and microalbuminuria) were measured in<br />

199 participants randomly selected by tertiles <strong>of</strong> current<br />

blood Pb.<br />

Mean blood Pb<br />

77.5 µg/dL (workers)<br />

19.8 µg/dL (controls)<br />

Mean blood Pb<br />

53.5 µg/dL<br />

Mean exposure duration<br />

11.6 yrs<br />

Mean cumulative blood Pb<br />

(defined as sum <strong>of</strong> the avg<br />

blood Pb in each yr over all yrs<br />

<strong>of</strong> employment; done in subset<br />

<strong>of</strong> 246 with past blood Pb data)<br />

579.0 (µg Η yr)/dL<br />

Mean historical blood Pb<br />

(defined as cumulative blood<br />

Pb divided by yrs <strong>of</strong> exposure)<br />

57.3 µg/dL<br />

Mean tibia Pb<br />

69.7 μg/g bone mineral<br />

(measured 2 yrs after initial<br />

study on random sample <strong>of</strong> 40)<br />

Mean BUN and serum creatinine not statistically<br />

different between exposed workers and controls.<br />

Limitations = data analysis.<br />

After adjustment <strong>for</strong> age, weight, and height,<br />

categorical current and historical blood Pb and zinc<br />

protoporphyrin were associated with serum creatinine<br />

and uric acid, in separate models. Associations<br />

between cumulative blood Pb or exposure duration<br />

and the renal outcomes were not observed.<br />

Among the EBE markers, only current blood Pb was<br />

borderline associated with NAG (p = 0.09).<br />

Associations with renal dysfunction were observed at<br />

blood Pb levels


AX6-103<br />

Table AX6-4.2 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Occupational Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Middle East (cont’d)<br />

El-Safty et al. (2004)<br />

Egypt<br />

Study date not<br />

provided<br />

Mortada et al. (2001)<br />

Egypt<br />

Study date not<br />

provided<br />

45 Pb workers with Pb job duration


AX6-104<br />

Table AX6-4.3. Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Osterloh et al. (1989)<br />

Northern CA<br />

Study date not<br />

provided<br />

Steenland et al. (1990)<br />

Michigan<br />

Diagnosis from<br />

1976-1984<br />

Europe<br />

Behringer et al.<br />

(1986)<br />

Germany<br />

Study date not<br />

provided<br />

40 male subjects with hypertensive nephropathy<br />

(hypertension preceded renal insufficiency; serum<br />

creatinine 1.8-4 mg/dL).<br />

24 controls with renal dysfunction from other causes.<br />

Patients recruited from the Kaiser Permanente Regional<br />

Laboratory database (large health maintenance<br />

organization) in northern Cali<strong>for</strong>nia.<br />

325 men with ESRD (diabetes, congenital and obstructive<br />

nephropathies excluded).<br />

Controls by random digit dialing, matched by age, race,<br />

and place <strong>of</strong> residence.<br />

16 patients with CRI (median serum creatinine =<br />

2.2 mg/dL) and gout.<br />

19 patients with CRI (median serum creatinine =<br />

5.1 mg/dL) without gout.<br />

21 healthy controls.<br />

Pb excretion in the 96 hrs after administration <strong>of</strong> 1 g<br />

EDTA iv.<br />

Mean blood Pb<br />

7.3 µg/dL (in both<br />

hypertensive nephropathy and<br />

controls CRI from other<br />

causes)<br />

Mean EDTA chelatable Pb<br />

levels<br />

153.3 µg/72 hrs (hypertensive<br />

nephropathy)<br />

126.4 µg/72 hrs (control CRI)<br />

Median blood Pb<br />

7.2 µg/dL (controls)<br />

11.5 µg/dL (CRI, no gout)<br />

15.3 µg/dL (CRI & gout)<br />

Median EDTA chelatable Pb<br />

(µg/4 days/1.73 m 2 )<br />

63.4 (controls)<br />

175.9 (CRI, no gout)<br />

261.3 (CRI & gout)<br />

No significant difference in EDTA chelatable Pb<br />

levels; highest chelatable Pb level was<br />

609.2 µg/72 hrs.<br />

Pb dose and serum creatinine were not correlated.<br />

Blood and chelatable Pb levels much lower than those<br />

reported by Wedeen et al. (1983) and<br />

Sanchez-Fructuoso et al. (1996).<br />

Only 17% <strong>of</strong> their study participants had a history <strong>of</strong><br />

possible Pb exposure based on questionnaire, again<br />

much lower than the two other studies.<br />

Risk <strong>of</strong> ESRD significantly related to moonshine<br />

alcohol consumption (OR = 2.43), as well as<br />

analgesic consumption, family history <strong>of</strong> renal<br />

disease, and occupational exposure to silica or<br />

solvents.<br />

EDTA chelatable Pb higher in gout patients who<br />

developed gout after CRI than those in which gout<br />

preceded CRI (statistical test results not mentioned or<br />

shown). Authors conclude a role <strong>for</strong> Pb in patients<br />

with gout occurring in setting <strong>of</strong> CRI and that Pb may<br />

contributes to renal function decline in established<br />

renal disease from other causes.<br />

Limitations = small groups, limited data analysis.


AX6-105<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Colleoni and<br />

D’Amico (1986)<br />

Italy<br />

(~1982-1985)<br />

Colleoni et al. (1993)<br />

Italy<br />

Study date not<br />

provided<br />

Craswell et al. (1987)<br />

Germany and<br />

Australia<br />

Study date not<br />

provided<br />

12 consecutive patients with CRI (mean serum<br />

creatinine = 3.3 mg/dL) and gout, renal diagnosis<br />

consistent with chronic interstitial nephritis in all; 7 had<br />

history <strong>of</strong> occupational Pb exposure.<br />

12 controls with chronic glomerulonephritis and no<br />

history <strong>of</strong> Pb exposure or gout.<br />

Pb excretion in the 48 hrs after administration <strong>of</strong> 1.5 g<br />

EDTA im.<br />

All 115 patients on hemodialysis at the time <strong>of</strong> the study;<br />

41 women.<br />

Blood Pb data from prior study <strong>of</strong> 383 healthy controls in<br />

same geographical area served as comparison.<br />

See discussion below under Australia.<br />

Mean EDTA chelatable Pb<br />

(µg/48 hrs)<br />

180 (CRI, no gout)<br />

505 (CRI & gout)<br />

Mean blood Pb<br />

(corrected <strong>for</strong> hemoglobin)<br />

19.9 µg/dL (patients)<br />

14.7 µg/dL (controls)<br />

Significantly higher EDTA chelatable Pb in the<br />

group with CRI and gout compared to CRI alone.<br />

EDTA chelatable Pb significantly correlated with<br />

serum creatinine in patients with CRI and gout but<br />

not CRI alone. Authors conclude that Pb is cause <strong>of</strong><br />

CRI with gout but renal insufficiency alone not<br />

responsible <strong>for</strong> increased Pb body burden (absence<br />

<strong>of</strong> evidence <strong>for</strong> reverse causation).<br />

Limitations = small sample size, limited data<br />

analysis.<br />

Significantly higher mean blood Pb in hemodialysis<br />

patients compared to healthy controls. 13% had<br />

blood Pb levels >30 µg/dL. Blood Pb level was not<br />

associated with duration <strong>of</strong> hemodialysis. Mean Pb<br />

levels higher in smokers and in relation to alcohol<br />

ingestion. Pb not detectable in dialysis fluids.<br />

Limited data analysis.


AX6-106<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Fontanellas et al.<br />

(2002)<br />

Spain<br />

Study date not<br />

provided<br />

Jones et al. (1990)<br />

Study location and<br />

date not provided;<br />

authors from UK<br />

Koster et al. (1989)<br />

Study location and<br />

date not provided;<br />

authors from<br />

Germany<br />

ALAD/restored ALAD as a possible index <strong>of</strong> Pb poisoning<br />

in chronic renal failure patients.<br />

27 dialysis patients.<br />

59 healthy controls.<br />

91 patients with CRI (median serum creatinine =<br />

2.5 mg/dL).<br />

46 age-matched normal controls.<br />

Pb excretion in the 4 days after<br />

1 g EDTA iv.<br />

Mean blood Pb<br />

8.1 µg/dL (patients)<br />

10.0 µg/dL (controls)<br />

Mean blood Pb<br />

(corrected <strong>for</strong> hemoglobin)<br />

11.2 µg/dL (patients)<br />

7.6 µg/dL (controls)<br />

Mean EDTA chelatable Pb<br />

164.7 µg/4 days /1.73 m²<br />

(patients)<br />

63.6 µg/4 days /1.73 m²<br />

(controls)<br />

Restored ALAD was measured after the addition <strong>of</strong><br />

zinc and dithiothreitol (DTT) to the incubation<br />

media.<br />

The ALAD/restored ALAD ratio was found to<br />

correlate with the results <strong>of</strong> the EDTA Pb<br />

mobilization test. Patients excreting I,115 to<br />

3860 µg Pb per 72 hrs had a ratio <strong>of</strong> 0.19 while<br />

chronic renal failure patients excreting an avg <strong>of</strong><br />

322 µg Pb (range 195 to 393) had a ratio <strong>of</strong> 0.47.<br />

In comparison, normal controls had a ratio <strong>of</strong> 0.5.<br />

Tibia Pb levels not correlated with blood Pb but were<br />

correlated with Pb in bone biopsy measurements<br />

(r = 0.42).<br />

Limitations = data analysis.<br />

CRI patients had significantly higher blood and<br />

EDTA chelatable Pb levels than controls. In 13% <strong>of</strong><br />

the CRI patients, EDTA chelatable Pb exceeded the<br />

highest value in controls (328.8 µg). EDTA<br />

chelatable Pb levels were correlated with serum<br />

creatinine in patients (r = 0.37; p < 0.007).<br />

Limitations = data analysis.


AX6-107<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Miranda-Carús et al.<br />

(1997)<br />

Spain<br />

1990-1994<br />

Nuyts et al. (1995)<br />

Belgium<br />

Study date not<br />

provided<br />

27 patients with gout and CRI.<br />

50 patients with gout only.<br />

26 controls with normal renal function and no gout.<br />

Multiple purine metabolism measures including serum<br />

urate, hypoxanthine, and xanthine, as well as their<br />

excretion, clearance and fractional excretion measures.<br />

Case-control study.<br />

272 cases with chronic renal failure (all types) matched to<br />

272 controls by age, sex and residence.<br />

Exposure assessed by 3 industrial hygienists blinded to<br />

case or control status.<br />

Mean blood Pb<br />

17.8 µg/dL (gout and CRI)<br />

14.9 µg/dL (gout only)<br />

12.4 µg/dL (controls)<br />

Mean EDTA chelatable Pb<br />

845 µg/120 hrs (gout and CRI)<br />

342 µg/120 hrs (gout only)<br />

215 µg/120 hrs (controls)<br />

Pb dose measures significantly higher in patients with<br />

gout and CRI compared to the other two groups.<br />

EDTA chelatable Pb inversely correlated with<br />

creatinine clearance. Each <strong>of</strong> the 2 patient groups<br />

were dichotomized by EDTA-chelatable Pb level <strong>of</strong><br />

600 μg/120 hrs, resulting in 3 small groups (n ranging<br />

from 6 to 14) and one group <strong>of</strong> 44 participants with<br />

gout and EDTA chelatable Pb below the cut-<strong>of</strong>f. No<br />

significant differences in mean purine metabolism<br />

measures were observed. It is not clear whether<br />

correlations between EDTA-chelatable Pb and the<br />

purine measures were assessed and if so whether the<br />

small groups were combined <strong>for</strong> this analysis. Thus<br />

lack <strong>of</strong> power may be one reason <strong>for</strong> the inconsistency<br />

with Lin’s work. Different Pb body burdens may be a<br />

factor as well.<br />

Uric acid parameters were unchanged following<br />

chelation in 6 participants with EDTA-chelatable<br />

above 600 µg/120 hrs. Again higher Pb body burdens<br />

may be a factor but the small number and limited<br />

details on the group make firm conclusions difficult.<br />

Significantly increased odds ratio <strong>for</strong> chronic renal<br />

failure with Pb exposure (OR = 2.11 [95% CI: 1.23,<br />

4.36]) as well as several other metals. Increased risk<br />

with diabetic nephropathy.


AX6-108<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Sánchez-Fructuoso<br />

et al. (1996)<br />

Spain<br />

Study date not<br />

provided<br />

296 patients:<br />

Group I = 30 normal control subjects<br />

Group <strong>II</strong> = 104 patients with essential HTN & normal<br />

renal function<br />

Group <strong>II</strong>I-A = 68 patients with HTN and CRI <strong>of</strong> uncertain<br />

etiology but presumed nephroangiosclerosis<br />

Group <strong>II</strong>I-B = 64 patients with HTN, CRI, and gout<br />

Group IV = 30 patients with CRI <strong>of</strong> known etiology<br />

Mean blood and EDTAchelatable<br />

Pb levels<br />

Group I<br />

16.7 µg/dL<br />

324 µg/72 hrs<br />

Group <strong>II</strong><br />

16.8 µg/dL<br />

487 µg/72 hrs<br />

Group <strong>II</strong>I-A<br />

18.5 µg/dL<br />

678 µg/72 hrs<br />

Group <strong>II</strong>I-B<br />

21.1 µg/dL<br />

1290 µg/72 hrs<br />

Group IV<br />

16.5 µg/dL<br />

321 µg/72 hrs<br />

EDTA chelatable Pb >600 µg/72 hrs in 16 patients in<br />

group <strong>II</strong>, 30 patients in group <strong>II</strong>I-A, 44 patients in<br />

group <strong>II</strong>I-B, but no patients in either group I and IV.<br />

Mean blood and EDTA chelatable Pb levels in the<br />

patients with CRI <strong>of</strong> known cause were not<br />

statistically different from controls with normal renal<br />

function. However, baseline urinary Pb excretion was<br />

lower in group IV. This provides conflicting evidence<br />

regarding the “reverse causality” hypothesis <strong>of</strong><br />

increased Pb burden due to decreased excretion in<br />

CRI.<br />

Significant correlations noted between bone Pb levels<br />

(assessed by biopsy) and EDTA chelatable Pb level in<br />

12 patients whose chelatable Pb levels were >600<br />

µg/72 hrs; provides support <strong>for</strong> validity <strong>of</strong> chelatable<br />

Pb levels in CRI.<br />

A positive correlation was observed between serum<br />

creatinine levels and EDTA-chelatable Pb levels<br />

>600 µg/72 hrs but not below this level.<br />

In group <strong>II</strong>I, mean measured creatinine clearance was<br />

significantly lower in those with EDTA chelatable Pb<br />

levels >600 μg/72 hrs compared to participants with<br />

chelatable Pb


AX6-109<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Van de Vyver et al.<br />

(1988)<br />

Belgium, France<br />

and Germany<br />

Study date not<br />

provided<br />

Winterberg et al.<br />

(1991)<br />

Study location and<br />

date not provided;<br />

authors from<br />

Germany<br />

Latin and South America<br />

Navarro et al. (1992)<br />

Venezuela<br />

Study date not<br />

provided<br />

Transiliac bone biopsies obtained from:<br />

11 cadavers without known Pb exposure and with normal<br />

renal function<br />

13 patients with CRI, gout and/or HTN 22 Pb workers<br />

153 dialysis patients<br />

Iliac crest bone Pb measured by biopsy in:<br />

8 controls<br />

8 patients with CRI<br />

14 dialysis patients<br />

18 dialysis patients.<br />

14 controls.<br />

Bone (biopsy) and blood levels <strong>of</strong> Pb and several other<br />

metals.<br />

Mean transiliac Pb levels<br />

5.5 µg/g (153 dialysis pts)<br />

20.6 µg/g (in highest 5%<br />

dialysis pts)<br />

3.7 µg/g (in 10 pts on dialysis<br />

due to analgesic nephropathy)<br />

6.3 µg/g (11 cadavers)<br />

30.1 µg/g (22 Pb workers)<br />

Mean iliac crest bone Pb levels<br />

1.63 µg/g (8 controls)<br />

2.18 µg/g (8 patients with<br />

CRI)<br />

3.59 µg/g (in 14 dialysis pts)<br />

Mean blood Pb<br />

5.2 µg/dL (patients)<br />

11.5 µg/dL (controls)<br />

Mean Pb in bone<br />

9.7 µg/g (patients)<br />

7.0 µg/g (controls)<br />

In 5% <strong>of</strong> the hemodialysis patients studied, bone Pb<br />

concentrations approximated the levels found in<br />

active Pb workers, suggesting Pb as a primary cause<br />

<strong>of</strong> their renal failure. Levels in the 10 patients with<br />

analgesic nephropathy were the lowest (all


AX6-110<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Australia<br />

Craswell et al. (1987)<br />

Germany and<br />

Australia<br />

Study date not<br />

provided<br />

German participants from industrialized area where<br />

chronic Pb nephropathy not previously observed.<br />

Gp 1 = 8 healthy controls (from hospital staff)<br />

Gp 2a = 12 CRI patients, no gout or Pb exposure<br />

Gp 2b = 7 CRI patients, no gout but + Pb exposure<br />

Gp 3a = 7 CRI patients with gout but no Pb exposure<br />

Gp 3b = 6 CRI patients with gout and Pb exposure<br />

Australian participants from Queensland site <strong>of</strong> known<br />

chronic Pb nephropathy.<br />

Gp 1 = 9 healthy controls (from hospital staff)<br />

Gp 2a = 14 CRI patients, no gout or Pb exposure<br />

Gp 2b = 11 CRI patients, no gout but + Pb exposure<br />

Gp 3a = 25 CRI patients with gout but no Pb exposure<br />

Gp 3b = 11 CRI patients with gout and Pb exposure<br />

CRI defined as serum creatinine ≥ 1.5 mg/dL<br />

“Excess” EDTA chelatable Pb defined as Pb excreted over<br />

4 days after EDTA minus twice baseline Pb excreted pre-<br />

EDTA.<br />

Median blood Pb (hemoglobin<br />

corrected)<br />

Gp 1<br />

German = 6.8 µg/dL<br />

Australian = 11.0 µg/dL<br />

Gp 2a<br />

German = 6.2 µg/dL<br />

Australian = 9.1 µg/dL<br />

Gp 2b<br />

German = 8.5 µg/dL<br />

Australian = 16.2 µg/dL<br />

Gp 3a<br />

German = 10.6 µg/dL<br />

Australian = 12.8 µg/dL<br />

Gp 3b<br />

German = 12.0 µg/dL<br />

Australian = 27.1 µg/dL<br />

Median “excess” EDTA<br />

chelatable Pb<br />

Gp 1<br />

German = 68.4 µg<br />

Australian =82.9 µg<br />

Gp 2a<br />

German = 126.4 µg<br />

Australian = 393.7 µg<br />

Gp 2b<br />

German = 489.0 µg<br />

Australian = 1181.1 µg<br />

Gp 3a<br />

German = 227.9 µg<br />

Australian = 808.1 µg<br />

Gp 3b<br />

German = 422.7 µg<br />

Australian = 1077.5 µg<br />

Using nonparametric statistical techniques due to<br />

skewed data, German participants excreted<br />

statistically less Pb than their Australian counterparts.<br />

Mean EDTA chelatable Pb levels were significantly<br />

higher in German patients with gout than in those<br />

without gout; the observed increase in the Australian<br />

patients was <strong>of</strong> borderline significance (p < 0.1).<br />

Limitations = small groups, limited data analysis.


AX6-111<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Australia (cont’d)<br />

Price et al. (1992)<br />

Queensland,<br />

Australia<br />

1981-1986<br />

Asia<br />

Lin and Lim (1992)<br />

Chinese population<br />

(likely in Taiwan)<br />

Study date not<br />

provided<br />

Lin and Huang<br />

(1994)<br />

Taiwan<br />

Study date not<br />

provided<br />

8 renal patients compared with age-matched controls.<br />

X-ray fluorescence <strong>of</strong> finger bone Pb conducted twice 5<br />

yrs apart.<br />

10 healthy controls.<br />

10 patients with CRI but no gout.<br />

8 patients with gout and subsequent CRI.<br />

6 patients with CRI and subsequent gout.<br />

Exclusionary criteria included + history <strong>of</strong> occupational or<br />

environmental Pb exposure.<br />

Group 1 = 10 patients with normal renal function and no<br />

gout; Group 2 = 10 patients with CRI (serum creatinine<br />

>1.4 mg/dL) and subsequent gout; Group 3 = 20 patients<br />

with CRI but no gout.<br />

All males.<br />

Pb body burden assessed with 1 g EDTA iv followed by<br />

72 hr urine collection.<br />

Mean EDTA chelatable Pb in<br />

µg/72 hrs/1.73 m 2<br />

90.2 (controls)<br />

98 (CRI, no gout)<br />

171.6 (gout, then CRI)<br />

359.8 (CRI, then gout)<br />

Mean EDTA chelatable Pb<br />

Gp 1 = 60.55 µg/ 72 hrs<br />

Gp 2 = 252.24 µg/ 72 hrs<br />

Gp 3 = 84.86 µg/ 72 hrs<br />

Authors conclude that Pb in bone half-life is similar in<br />

renal patients compared to age-matched controls.<br />

Study limitations substantial, however.<br />

Limitations = small numbers (although bone Pb<br />

measured in more patients, many were below the limit<br />

<strong>of</strong> detection, inclusion <strong>of</strong> outliers without <strong>for</strong>mal<br />

statistical analysis.<br />

Pb body burden higher in patients with CRI and gout,<br />

especially when CRI precedes gout.<br />

Limitations = small sample sizes, statistical analysis.<br />

Mean EDTA chelatable Pb and serum urate<br />

significantly higher in the patients with gout. After<br />

adjustment <strong>for</strong> creatinine clearance, log trans<strong>for</strong>med<br />

EDTA chelatable Pb was significantly associated with<br />

serum urate levels (∃ = 0.757 [95% CI: 0.142, 1.372];<br />

p < 0.05), daily urate excretion (∃ = !60.15 [95% CI:<br />

!118.1, !2.16]; p < 0.05), urate clearance (∃ = !0.811<br />

[95% CI: !1.34, !0.282]; p < 0.05), and fractional<br />

urate excretion (∃ = !1.535 [95% CI: !2.723, !0.347];<br />

p < 0.05). EDTA chelatable Pb not associated with<br />

creatinine clearance.<br />

Limitations = small sample sizes, limited adjustment<br />

in regression analyses.


AX6-112<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin and Lim (1994)<br />

Taiwan<br />

Study date not<br />

provided<br />

Lin et al. (1999)<br />

Taiwan<br />

Study date not<br />

provided<br />

Gp 1 = 12 healthy controls.<br />

Gp 2 = 10 patients with HTN.<br />

Gp 3 = 12 patients with HTN, then CRI (hypertensive<br />

nephropathy).<br />

Gp 4 = 12 patients with CRI only.<br />

Gp 5 = 12 patients with CRI not due to HTN, but<br />

subsequent HTN.<br />

32 patients selected from 102 patients with serum<br />

creatinine from 1.5–4.0 mg/dL who were followed in the<br />

Institution’s outpatient clinics.<br />

Eligibility criteria included serum creatinine from 1.5 –<br />

4.0 mg/dL, stable renal function over 6 mos be<strong>for</strong>e study<br />

entry; controlled blood pressure and cholesterol; daily<br />

protein intake 150 but


AX6-113<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin et al. (2001a)<br />

Taiwan<br />

Study date not<br />

provided<br />

24 mo prospective observational study<br />

110 patients with CRI dichotomized by EDTA chelatable<br />

Pb level <strong>of</strong> 80 µg/72 hrs into two groups <strong>of</strong> 55 each.<br />

Eligibility criteria included serum creatinine from 1.5 – 4.0<br />

mg/dL, stable renal function (decrease in GFR


AX6-114<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin et al. (2001a)<br />

(cont’d)<br />

3 mo clinical trial <strong>of</strong> chelation with 1 yr follow-up<br />

At 24 mos, 36 patients whose EDTA chelatable Pb levels<br />

were 80 - 600 μg/72 hrs and serum creatinine levels <strong>of</strong><br />


AX6-115<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin et al. (2001b)<br />

Study location and<br />

date not provided;<br />

authors from Taiwan<br />

101 patients with CRI (defined as serum creatinine<br />

between 1.5 and 3.0 mg/dL).<br />

67 with CRI and gout.<br />

34 with CRI only.<br />

Eligibility criteria included no known history <strong>of</strong> Pb<br />

exposure, certain diagnoses, and medications. CRI must<br />

have preceded gout diagnosis.<br />

Randomized chelation trial<br />

30 participants with CRI, gout, and EDTA-chelatable Pb<br />

levels between 80.2 and 361 μg/72 hrs randomized to<br />

either a treatment group receiving 1 gram EDTA iv per wk<br />

<strong>for</strong> 4 wks (N = 20) or to a control group who received<br />

glucose in normal saline iv.<br />

Mean blood Pb<br />

5.4 µg/dL (CRI and gout)<br />

4.4 µg/dL (CRI only)<br />

Mean EDTA-chelatable Pb<br />

138.1 µg/72 hrs (CRI and<br />

gout)<br />

64.2 µg/72 hrs (CRI only)<br />

(p < 0.01)<br />

In 101, EDTA-chelatable Pb higher in patients with<br />

CRI and gout compared to those with CRI only.<br />

EDTA-chelatable Pb, but not blood Pb, was<br />

associated positively with serum urate and negatively<br />

with daily urate excretion, urate clearance, and<br />

fractional urate excretion.<br />

Randomized chelation trial<br />

The two groups had similar uric acid, renal function,<br />

and Pb measures pre-chelation. In the treated group,<br />

mean EDTA-chelatable Pb declined from 159.2 to<br />

41 μg/72 hrs; mean serum urate decreased from 10.2<br />

to 8.6 mg/dL (% change compared to the control<br />

group = !22.4 [95% CI: !46.0, !1.5]; p = 0.02), and<br />

mean urate clearance increased from 2.7 to<br />

4.2 mL/min (% change compared to the control group<br />

= 67.9 [95% CI: 12.2, 121.2]; p < 0.01). Daily and<br />

fractional urate excretion were also significantly<br />

different between the two groups. Mean measured<br />

creatinine clearance increased from 50.8 to<br />

54.2 mL/min (% change compared to the control<br />

group = 8.0 [95% CI: !0.4, 20.1]; p = 0.06).


AX6-116<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin et al. (2002)<br />

Study location and<br />

date not provided;<br />

authors from Taiwan<br />

84 healthy participants.<br />

27 participants with gout.<br />

All with normal renal function (defined as serum<br />

creatinine ≤1.4 mg/dL).<br />

Participants with a history <strong>of</strong> occupational heavy metal<br />

exposure, EDTA-chelatable Pb levels >600 μg/72 hrs, or<br />

systemic diseases were excluded.<br />

Randomized chelation trial<br />

24 participants with EDTA-chelatable Pb levels between<br />

75 and 600 μg/72 hrs randomized to either a treatment<br />

group receiving 1 gram EDTA iv per wk <strong>for</strong> 4 wks<br />

(N = 12) or to a control group who received glucose in<br />

normal saline i.v.<br />

Multiple linear regression, adjustment <strong>for</strong> age, sex, BMI,<br />

daily protein intake, and creatinine clearance.<br />

Mean blood Pb<br />

3.9 µg/dL (controls)<br />

4.2 µg/dL (gout)<br />

Mean EDTA-chelatable Pb<br />

45 µg/72 hrs (controls)<br />

84 µg/72 hrs (gout)<br />

(p < 0.0001)<br />

Significantly higher mean EDTA-chelatable Pb and<br />

lower urate clearance were present in patients with<br />

gout compared to those without (3.7 vs. 6.0 mL/min<br />

/1.73 m 2 ; p < 0.001 <strong>for</strong> urate clearance).<br />

After adjustment, EDTA-chelatable Pb associated<br />

with all four uric acid measures (serum urate, daily<br />

urate excretion, urate clearance, and fractional urate<br />

excretion). Blood Pb associated with serum urate.<br />

All associations in same direction as in Lin et al.<br />

(2001).<br />

Randomized chelation trial.<br />

The two groups had similar urate, renal function, and<br />

Pb measures pre-chelation. In the treated group, mean<br />

blood and EDTA-chelatable Pb levels declined (from<br />

5.0 to 3.7 μg/dL and 110 to 46 μg/72 hrs,<br />

respectively). Statistically significant improvement<br />

observed in all four urate measures in the treated<br />

group compared to the control group.


AX6-117<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin et al. (2003)<br />

Study location and<br />

date not provided;<br />

authors from Taiwan<br />

24 mo prospective observational study<br />

202 patients with CRI<br />

Eligibility criteria included serum creatinine from 1.5 - 3.9<br />

mg/dL, stable renal function (decrease in GFR


AX6-118<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lin et al. (2003)<br />

(cont’d)<br />

Study location and<br />

date not provided;<br />

authors from Taiwan<br />

27 mo clinical trial <strong>of</strong> chelation<br />

At 24 mos, 64 patients whose EDTA chelatable Pb levels<br />

were 80 - 600 μg/72 hrs and serum creatinine levels <strong>of</strong><br />


AX6-119<br />

Table AX6-4.3 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in the Patient Population<br />

Reference, Study<br />

Location, and Period<br />

Asia (cont’d)<br />

Study Description Pb Measurement Findings, Interpretation<br />

Yu et al. (2004)<br />

Study location and<br />

date not provided;<br />

authors from Taiwan<br />

121 patients followed over a four yr observational<br />

period.<br />

Eligibility criteria included serum creatinine from 1.5<br />

-3.9 mg/dL, stable renal function (decrease in GFR


AX6-120<br />

Table AX6-4.4. Renal Effects <strong>of</strong> <strong>Lead</strong> on Mortality<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Cooper (1988);<br />

Cooper et al. (1985)<br />

16 U.S. plants<br />

Employment between<br />

1946 and 1970;<br />

mortality from 1947<br />

to 1980<br />

Steenland et al. (1992)<br />

Idaho<br />

Employed between<br />

1940 and 1965;<br />

mortality up to 1988<br />

4519 male battery plant workers.<br />

2300 male Pb production workers.<br />

Employed <strong>for</strong> at least one yr between 1946 and 1970.<br />

Cause <strong>of</strong> death per death certificate (extrapolated when<br />

missing).<br />

Standardized mortality ratios (SMRs) compared with<br />

national age-specific rates. PMR also assessed.<br />

Analyzed separately by battery and Pb production, by hire<br />

date be<strong>for</strong>e and after 1/1/1946, and by cumulative yrs <strong>of</strong><br />

employment (1-9, 10-19, 20+).<br />

1990 male Pb smelter workers.<br />

Employed in a Pb-exposed department <strong>for</strong> at least one yr<br />

between 1940 and 1965.<br />

Vital status was determined using records from the Social<br />

Security Administration and the National Death Index.<br />

Mean blood Pb<br />

63 µg/dL in n = 1326 battery<br />

workers<br />

80 µg/dL in n = 537<br />

production workers<br />

Past Pb exposures poorly<br />

documented prior to 1960<br />

Mean blood Pb<br />

56.3 µg/dL (n = 173, measured<br />

in 1976)<br />

High Pb exposure defined as<br />

workers from departments<br />

with an avg >0.2 mg/m 3<br />

airborne Pb or ∃50% <strong>of</strong> jobs<br />

had avg levels more than twice<br />

that level (1975 survey). In<br />

this category, n = 1,436.<br />

Follow-up >90% in both groups; 2339 deaths<br />

observed.<br />

“Chronic or unspecified nephritis” SMR:<br />

222 (95% CI: 135, 343) in battery workers<br />

265 (95% CI: 114, 522) in Pb production workers<br />

“Other hypertensive disease” SMR (“includes HTN<br />

and related renal disease without mention <strong>of</strong> heart<br />

disease)”:<br />

320 (95% CI: 197, 489) in battery workers<br />

475 (95% CI: 218, 902) in Pb production workers<br />

Race adjusted proportionate mortality ratios analyses<br />

similar.<br />

Nephritis deaths observed primarily in workers hired<br />

be<strong>for</strong>e 1946.<br />

Limitations = due to mortality analysis (inaccuracies<br />

<strong>of</strong> death certificates, exposure assessment generally<br />

limited).<br />

Compared to the U.S. white male population, the<br />

standardized mortality ratio (SMR) <strong>for</strong> chronic kidney<br />

disease, based on only 8 deaths, was 1.26 (95%<br />

CI = 0.54, 2.49). SMR = 1.55 in high Pb exposure<br />

group, also not significant. The SMR <strong>for</strong> chronic<br />

kidney disease increased with duration <strong>of</strong> exposure<br />

from 0.79 in workers exposed 1-5 yrs to 2.79 in<br />

workers exposed >20 yrs; however SMR was not<br />

significant.


AX6-121<br />

Table AX6-4.4 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> on Mortality<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Fanning (1988)<br />

UK<br />

Deaths from<br />

1926-1985<br />

Deceased males identified through pension records <strong>of</strong> Pb<br />

battery and other factory workers.<br />

867 deaths <strong>of</strong> mean with high Pb exposure compared to<br />

1206 men with low or no Pb exposure.<br />

Range <strong>of</strong> blood Pb<br />

40-80 µg/dL since ~1968 in<br />

high Pb exposure group;<br />

thought not to have had<br />

clinical Pb poisoning due to<br />

medical surveillance.<br />


AX6-122<br />

Table AX6-4.5. Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Hu (1991)<br />

U.S.<br />

Study date not<br />

provided<br />

Loghman-Adham<br />

(1998)<br />

Chicago, IL<br />

Study date not<br />

provided<br />

21 <strong>of</strong> 192 adults who were hospitalized at Boston<br />

Children’s Hospital between 1932 to 1942 <strong>for</strong> childhood<br />

Pb poisoning were traced to a Boston area address.<br />

Matched on age, sex, race, and neighborhood to<br />

21controls.<br />

134 children and young adults, 8 to 13 yrs after chelation<br />

therapy <strong>for</strong> severe Pb poisoning.<br />

Mean age at poisoning = 2.3 yrs<br />

Mean age at follow-up = 13.4 yrs<br />

Mean (SD) blood Pb<br />

6.0 µg/dL (Pb poisoned)<br />

7.5 µg/dL (controls)<br />

Mean peak blood Pb level<br />

121 µg/dL<br />

Mean blood Pb level at time<br />

<strong>of</strong> study<br />

18.6 µg/dL<br />

No significant differences in blood Pb level, serum<br />

creatinine, or BUN. Mean measured creatinine<br />

clearance higher in the previously Pb poisoned group<br />

compared to controls (112.8 vs. 88.8 mL/min/1.73 m 2<br />

[p < 0.01]). Mean in the Pb exposed group was also<br />

higher than the predicted value <strong>of</strong> 94.2 mL/min/1.73<br />

m 2 from the nomogram <strong>of</strong> Rowe et al. (1976).<br />

Suggests Pb-related hyperfiltration. As noted in<br />

section 6.4, one survivor, identified but not included<br />

in the study, had disease consistent with Pb<br />

nephropathy.<br />

Limitations = small study size and concern <strong>for</strong><br />

survivor bias in the study group.<br />

Mean serum creatinine was normal (0.8 mg/dL).<br />

Calculated creatinine clearance normal in all but 3<br />

children. No correlation between either initial or<br />

current blood Pb and serum creatinine or calculated<br />

creatinine clearance.<br />

Urinary α-amino nitrogen concentrations were<br />

significantly increased compared with 19 healthy age<br />

matched controls and were correlated with current<br />

blood Pb levels. Thirty-two children (24%) had<br />

glycosuria. Fractional excretion <strong>of</strong> phosphate,<br />

however, was normal in all children. The author<br />

concluded that a partial Fanconi syndrome could<br />

persist <strong>for</strong> up to 13 yrs after childhood Pb poisoning.<br />

The author notes that the prognostic significance <strong>of</strong><br />

this is unknown at present.


AX6-123<br />

Table AX6-4.5 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

McDonald and Potter<br />

(1996)<br />

Boston, MA<br />

1991<br />

Moel and Sachs (1992)<br />

Chicago, IL<br />

1974-1989<br />

Bernard et al. (1995b)<br />

Czech Republic<br />

Study date not<br />

provided<br />

454 pediatric hospital patients who were diagnosed with<br />

Pb poisoning between 1923 and 1966 were traced<br />

through 1991.<br />

Mortality study, comparison with U.S. population.<br />

62 participants with blood Pb >100 µg/dL, diagnosed and<br />

chelated between 1966 and 1972, together with 19 agematched<br />

control siblings with initial blood Pbs less than<br />

40 µg/dL. Mean age at follow-up = 22 yrs.<br />

Renal outcomes = serum creatinine, uric acid, and ∃ 2microglobulin,<br />

fractional excretion <strong>of</strong> ∃2-microglobulin,<br />

urinary protein:creatinine ratio, and tubular reabsorption<br />

<strong>of</strong> phosphate.<br />

144 children living close to a Pb smelter (exposed groups<br />

1 and 2).<br />

51 controls living in a rural area presumed to be<br />

relatively unpolluted with Pb.<br />

Mean age = 13.5 yrs.<br />

Renal outcome measures included urinary albumin, RBP,<br />

NAG, Clara cell protein, and ∃2-microglobulin.<br />

Retinol binding protein<br />

73.8 µg/g creatinine (controls)<br />

109.4 µg/g creatinine (exposed group 1)<br />

117.8 µg/g creatinine (exposed group 2)<br />

∃2-microglobulin<br />

60.3 µg/g creatinine (controls)<br />

89.1 µg/g creatinine (exposed group 1)<br />

66.4 µg/g creatinine (exposed group 2)<br />

NAG<br />

1.56 IU/g creatinine (controls)<br />

2.32 IU/g creatinine (exposed group 1)<br />

1.46 IU/g creatinine (exposed group 2)<br />

Multiple linear adjusting <strong>for</strong> age and gender.<br />

Mean initial blood Pb<br />

150.3 µg/dL (highly poisoned<br />

as children)<br />

Data <strong>for</strong> siblings not available<br />

as levels


AX6-124<br />

Table AX6-4.5 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

De Burbure et al.<br />

(2006)<br />

France, the Czech<br />

Republic, and Poland<br />

Study date not<br />

provided<br />

Factor-Litvak et al.<br />

(1999)<br />

Kosovo, Yugoslavia<br />

1985-1993<br />

804 exposed and control children.<br />

Exposed children recruited from residents near historical<br />

nonferrous smelters, must have lived ∃8 yrs near<br />

smelters.<br />

Mean age = 10 yrs; range = 8.5-12.3 yrs.<br />

Renal outcome measures included serum creatinine,<br />

cystatin C and ß 2-microglobulin as well as urinary RBP,<br />

NAG, Clara cell protein.<br />

577 children followed at 6 mo intervals through 7.5 yrs<br />

<strong>of</strong> age.<br />

Divided into a high exposure and a low exposure group,<br />

based on residence in Kosovska Mitrovica with a Pb<br />

smelter, refinery, and battery plant or in Pristina, 25 miles<br />

away.<br />

Renal outcome = Proteinuria assessed with a dipstick.<br />

Multiple logistic regression modeling <strong>of</strong> proteinuria<br />

dichotomized as either any or none, adjusting <strong>for</strong><br />

socioeconomic status, maternal education/ intelligence,<br />

and quality <strong>of</strong> childrearing environment.<br />

Mean blood Pb<br />

Ranged from 2.8 to 4.2 mg/dL<br />

in various control and exposed<br />

groups.<br />

Urinary cadmium, arsenic and<br />

mercury as well as blood<br />

cadmium also assessed.<br />

Mead blood Pb from graph<br />

peaked at ~38 µg/dL between<br />

ages 3-5 in Kosovska<br />

Mitrovica and at ~10 µg/dL in<br />

controls.<br />

Blood Pb level ranged from<br />

1 to 70 µg/dL.<br />

Serum concentrations <strong>of</strong> creatinine, cystatin C, and<br />

ß 2-microglobulin negatively correlated with blood Pb<br />

levels.<br />

Authors state suggestive <strong>of</strong> an early renal<br />

hyperfiltration that avgd 7% in the upper quartile <strong>of</strong><br />

PbB levels (>5.5 µg/dL; mean 7.84 µg/dL).<br />

In higher exposed group, adjusted OR <strong>for</strong> proteinuria<br />

was 3.5 (95% CI: 1.7, 7.2); adjusted odds <strong>of</strong><br />

proteinuria increased by 1.15 (95% CI: 1.1, 1.2) per<br />

unit increase in blood Pb in the higher exposed group.<br />

Proteinuria unrelated to blood Pb in lower exposed<br />

control group.<br />

Limitations = limited renal outcomes assessed, high<br />

dropout rate in the study.


AX6-125<br />

Table AX6-4.5 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Fels et al. (1998)<br />

Poland<br />

1995<br />

_ktem et al. (2004)<br />

Turkey<br />

Study date not<br />

provided<br />

112 children (50 controls, 62 exposed).<br />

Mean age = 9.9 yrs and 10.6 yrs in controls and exposed<br />

group, respectively.<br />

Numerous (29) renal outcome measures were examined<br />

including serum creatinine and ∃ 2-microglobulin, and<br />

urinary NAG, RBP, Clara cell protein, ∃2-microglobulin,<br />

6-keto-prostaglandin F 1α (6-keto-PGF 1α), prostaglandin<br />

E2 (PGE 2) and thromboxane B 2 (TXB 2).<br />

Urinary RBP<br />

46 µg/g creatinine (exposed)<br />

42 µg/g creatinine (controls)<br />

Urinary ∃ 2-microglobulin<br />

89 µg/g creatinine (exposed)<br />

37 µg/g creatinine (controls)<br />

Serum creatinine<br />

0.63 mg/dL (exposed)<br />

0.63 mg/dL (controls)<br />

79 adolescent auto repair workers (mean age 17.3 yrs).<br />

71 rural adolescents as negative controls (mean age 17.0<br />

yrs).<br />

Renal outcomes = urinary NAG, ∃ 2-microglobulin, uric<br />

acid, and calcium; blood urea nitrogen (BUN), serum<br />

creatinine and uric acid.<br />

Mean blood Pb<br />

13.3 µg/dL (exposed)<br />

3.9 µg/dL (controls)<br />

Mean blood Pb<br />

7.79 µg/dL (exposed workers)<br />

1.6 µg/dL (controls)<br />

Significantly higher mean serum ∃ 2-microglobulin,<br />

and urinary transferrin, 6-keto-PGF1α, thromboxane<br />

B 2, epidermal growth factor, ∃ 2-microglobulin, PGE 2,<br />

and Clara cell protein in the exposed children. In<br />

contrast, NAG-B was lower in the exposed group.<br />

Categorical blood Pb associated with prevalence <strong>of</strong><br />

values above the upper reference limits <strong>for</strong> several<br />

biomarkers. Urinary 6-keto-PGF 1α, TXB 2, ∃ 2microglobulin,<br />

Clara cell protein, epidermal growth<br />

factor and PGE 2 positively correlated with blood Pb<br />

(r = 0.441, 0.225, 0.203, 0.261, 0.356, and 0.23,<br />

respectively; all with significant p-values).<br />

Limitations = data analysis, limited adjustment.<br />

No difference in mean BUN, serum creatinine, uric<br />

acid, or GFR (apparently estimated) between workers<br />

and controls.<br />

Urinary NAG and calcium significantly higher in<br />

workers compared to controls. Urinary NAG<br />

positively correlated blood Pb (r = 0.427).<br />

Limitations = data analysis, lack <strong>of</strong> adjustment.


AX6-126<br />

Table AX6-4.5 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Price et al. (1999)<br />

Belgium, Poland,<br />

Germany and Italy<br />

Study date not<br />

provided<br />

Sch≅rer et al. (1991)<br />

Germany<br />

1988-1989<br />

S⎯nmez et al. (2002)<br />

Turkey<br />

Study date not<br />

provided<br />

Urinary Pb measured in 481 European children (236<br />

controls, 245 exposed) aged 6 – 14 yrs.<br />

Several renal outcome measures assessed including<br />

urinary NAG and ∃ 2-microglobulin; values not reported.<br />

22 children, age 5-14 yrs, with CRI.<br />

20 siblings or neighbors as lower exposed group.<br />

16 control children without known Pb exposure.<br />

39 adolescent auto repair workers (mean age 16.2 yrs).<br />

13 adult battery workers as positive controls (mean age<br />

32 yrs).<br />

29 rural adolescents as negative controls (mean age<br />

14.8 yrs).<br />

Serum creatinine<br />

0.99 mg/dL (exposed group)<br />

0.99 mg/dL (positive/ adult controls)<br />

0.89 mg/dL (negative/ adolescent controls)<br />

Urinary NAG<br />

4.7 IU/g creatinine (exposed group)<br />

7.4 IU/g creatinine (positive/ adult controls)<br />

3.1 IU/g creatinine (negative/ adolescent controls)<br />

Mean urinary Pb<br />

Range from 3.9 to 7.2 µg/g<br />

creatinine (controls)<br />

Range from 5.2 to 24.6 µg/g<br />

creatinine (exposed)<br />

Mean blood Pb<br />

2.9 µg/dL in children with<br />

CRI, not tested in other groups<br />

Mean dental Pb content<br />

2.8 µg/g in children with CRI<br />

1.7 µg/g in sibs/neighbors<br />

1.4 µg/g in controls<br />

Mean blood Pb<br />

8.13 µg/dL (exposed group)<br />

25.3 µg/dL<br />

(positive/adult controls)<br />

3.49 µg/dL<br />

(negative/ adolescent controls)<br />

Urinary Pb generally higher in exposed children as<br />

compared to controls. Authors unexpectedly found<br />

substantial differences in renal biomarkers by study<br />

site. Authors note several renal biomarkers differed<br />

between exposed and control groups. Also<br />

questioned the use <strong>of</strong> “control” groups in ubiquitous<br />

exposures.<br />

Pb levels in teeth significantly higher in both the<br />

patient and sibling/neighbor control groups compared<br />

to the unexposed control group.<br />

All participants had normal blood urea, creatinine,<br />

and uric acid levels as well as normal routine<br />

urinalysis.<br />

Blood Pb level and urinary NAG significantly higher<br />

in adolescent auto repair workers compared to the<br />

negative control group.<br />

Limitations = data analysis, lack <strong>of</strong> adjustment.


AX6-127<br />

Table AX6-4.5 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Staessen et al. (2001)<br />

Belgium<br />

1999<br />

Verberk et al. (1996)<br />

Romania<br />

1991-1992<br />

100 exposed and 100 control children.<br />

Mean age = 17 yrs.<br />

Two exposed groups were recruited from industrialized<br />

suburbs while the control group was recruited from a rural<br />

area.<br />

∃ 2-microglobulin<br />

5.22 µg/mmol creatinine (controls)<br />

5.3 µg/mmol creatinine (exposed group 1)<br />

9.09 µg/mmol creatinine (exposed group 2)<br />

Cystatin-C<br />

0.65 mg/L (controls)<br />

0.63 mg/L (exposed group 1)<br />

0.71 mg/L (exposed group 2)<br />

Multiple linear regression adjusting <strong>for</strong> sex and smoking<br />

status.<br />

151 children who resided at different distances from a Pb<br />

smelter.<br />

Mean age = 4.6 yrs.<br />

Renal outcomes = urinary RBP, NAG, α1-microglobulin,<br />

albumin and alanine aminopeptidase.<br />

Geometric means<br />

Urinary RBP<br />

49.4 µg/g creatinine<br />

Urinary NAG<br />

6.9 U/g creatinine<br />

Urinary α 1-microglobulin<br />

2.4 mg/g creatinine<br />

Urinary alanine aminopeptidase<br />

19.8 U/g creatinine<br />

Multiple regression analysis adjusting <strong>for</strong> age and gender.<br />

Mean blood Pb<br />

1.5 µg/dL (controls)<br />

1.8 µg/dL (exposed group 1)<br />

2.7 µg/dL (exposed group 2)<br />

Mean (SD) blood Pb<br />

34.2 (22.4) µg/dL<br />

Blood Pb, ∃ 2-microglobulin, and Cystatin-C levels<br />

higher in exposed group 2 as compared to controls and<br />

exposed group 1.<br />

After adjustment <strong>for</strong> sex and smoking status, blood Pb<br />

was associated with both ∃ 2-microglobulin and<br />

cystatin-C. A two-fold increase in blood Pb was<br />

associated with a 3.6% (95% CI: 1.5, 5.7) increase in<br />

Cystatin-C and a 16% (95% CI: 2.7, 31) increase in<br />

∃ 2-microglobulin. Blood cadmium was not associated<br />

with either outcome.<br />

After adjustment <strong>for</strong> age and gender, a 10 µg/dL<br />

increase in blood Pb was associated with a 13.5%<br />

increase in NAG excretion (90% CI: 10.2, 17).<br />

No threshold was observed. No other significant<br />

associations noted.


AX6-128<br />

Table AX6-4.5 (cont’d). Renal Effects <strong>of</strong> <strong>Lead</strong> in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Africa<br />

Diouf et al. (2003)<br />

Senegal<br />

1998<br />

38 Senegalese children (19 exposed, 19 controls).<br />

Age range = 8 – 12 yrs old.<br />

Renal function assessed by measuring urinary alphaglutathione<br />

S-transferase (αGST).<br />

Mean (SD) blood Pb<br />

10.7 (1.7) µg/dL (exposed)<br />

6.1 (1.8) µg/dL (controls)<br />

Blood Pb significantly higher in exposed group (urban<br />

dwellers) as compared to controls (rural dwellers).<br />

Unclear as to whether αGST was higher or lower in<br />

controls as compared to exposed group (stated to be<br />

higher in controls in the results section BUT stated to be<br />

higher in the exposed group in the discussion).<br />

Regardless, the difference was not statistically<br />

significant.<br />

Limitations = small sample size, data analysis.


ANNEX TABLES AX6-5<br />

AX6-129


AX6-130<br />

Table AX6-5.1. Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Meta-analysis<br />

Nawrot et al. (2002)<br />

31 U.S. and European<br />

studies, community<br />

and occupationally<br />

exposed, published<br />

between 1981 and<br />

2001.<br />

48 different groups, 32 <strong>of</strong> which<br />

were only <strong>of</strong> men, 15 <strong>of</strong> which were<br />

only <strong>of</strong> women, and one studying<br />

both sexes. Total meta-analysis<br />

N > 58,490. Age ranged from 15 to<br />

93 yrs, depending on the study.<br />

Two methods <strong>of</strong> meta-analysis were<br />

used, subject-weighted and nonweighted,<br />

using study-reported<br />

effect sizes and standard errors,<br />

trans<strong>for</strong>med from the original study<br />

specification <strong>of</strong> blood Pb (linear,<br />

logarithmic, or blood Pb group) to a<br />

single effect size <strong>for</strong> doubling <strong>of</strong><br />

blood Pb. Also did analyses<br />

stratified by race and sex.<br />

Mean blood Pb concentration<br />

across studies ranged from<br />

2.3 to 63.8 µg/dL. Total<br />

range <strong>of</strong> blood Pb across<br />

studies was 0 to 97.9 µg/dL.<br />

Each doubling <strong>of</strong> blood Pb was associated with a significant 1.0 mm Hg<br />

(95% CI: 0.5, 1.4) increase in systolic blood pressure and a significant 0.6<br />

mm Hg (95% CI: 0.4, 0.8) increase in diastolic blood pressure. Stated that<br />

differences in Pb effect were not statistically different between sexes, but did<br />

not describe test nor give statistics other than p-values. Presented black and<br />

white differences as a trend <strong>for</strong> blacks to be “more susceptible than whites,”<br />

but presented no tests.<br />

Statistically examined assumptions <strong>of</strong> homogeneity <strong>of</strong> effect and found no<br />

significant heterogeneity. Tested <strong>for</strong> publication bias (statistically significant<br />

results tend to be published more than non-significant results) and found no<br />

evidence. Found no significant effects <strong>of</strong> removing one study at a time in<br />

sensitivity analysis. It appears that the presented results <strong>of</strong> effect sizes and<br />

confidence intervals were calculated by the subject-weighted method, but this<br />

was not made explicit. Included some studies that presented no Pb<br />

coefficients or standard errors, assuming effect size <strong>of</strong> zero, though the<br />

reported effect sizes without these studies did not appear to be different from<br />

overall effect sizes. For studies using a linear Pb measure, effect sizes were<br />

calculated by doubling the arithmetic mean blood Pb. If the concentrationresponse<br />

curve <strong>for</strong> the Pb-blood pressure relationship was really better<br />

characterized by a log-linear function, the authors’ use <strong>of</strong> studies with a linear<br />

blood Pb term with high avg blood Pb led to over-estimation <strong>of</strong> the slope <strong>of</strong><br />

the relationship and those studies with low blood Pb avgs produced an underestimation<br />

<strong>of</strong> the slope <strong>of</strong> the relationship.


AX6-131<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Cheng et al. (2001)<br />

U.S.-Boston,<br />

Normative Aging<br />

Study (VA)<br />

1991-1997<br />

833 males (~97% white), avg age<br />

(SD):<br />

65.5 (7.2) Normotensive subjects,<br />

N = 337<br />

68.3 (7.8) Borderline hypertensive<br />

subjects, N = 181<br />

67.9 (6.8) Definite hypertensive<br />

subjects, N = 314<br />

474 males with no history <strong>of</strong><br />

hypertension at first measurement,<br />

returning up to 6 yrs later <strong>for</strong><br />

hypertension study.<br />

Linear multiple regression models <strong>of</strong><br />

blood pressure and Cox proportional<br />

hazard models <strong>of</strong> new cases <strong>of</strong><br />

hypertension after up to 7 yrs, with<br />

one group <strong>of</strong> covariates <strong>for</strong>ced into<br />

models based on biological<br />

plausibility and another group<br />

<strong>for</strong>ced based on significant<br />

univariate or bivariate results or<br />

>20% effect modification <strong>of</strong> Pb<br />

variable coefficient in multiple<br />

models. Linear blood Pb, tibia Pb,<br />

and patella Pb <strong>for</strong>ced in separate<br />

models.<br />

Arithmetic mean (SD) blood<br />

Pb:<br />

5.9-6.4 µg/dL (3.7-4.2),<br />

depending on hypertension<br />

group (only data shown).<br />

Multiple regression models <strong>of</strong> blood pressure always included age, agesquared,<br />

BMI, family history <strong>of</strong> hypertension, daily alcohol consumption,<br />

and daily calcium consumption. Increasing tibia Pb concentration was<br />

associated with increased systolic blood pressure (diastolic not addressed) in<br />

baseline measurements in subjects (n = 519) free from definite hypertension<br />

(systolic >160 mm Hg, diastolic >95 mm Hg, or taking daily antihypertensive<br />

medication). Each increase <strong>of</strong> 10 µg/g tibia Pb concentration was associated<br />

with an increase in systolic blood pressure <strong>of</strong> 1.0 mm Hg (95% CI: 0.01,<br />

1.99). Patella and linear blood Pb were not significant.<br />

Cox proportional hazard models always included age, age-squared, BMI, and<br />

family history <strong>of</strong> hypertension. In follow up (n = 474), only increasing<br />

patella Pb predicted increasing risk <strong>of</strong> definite hypertension in those<br />

classified as normotensive at baseline. For every 10 µg/g increase in patella<br />

Pb risk ratio increased 1.14 (95% CI: 1.02, 1.28). Combining borderline<br />

hypertension (systolic 141-160 mm Hg or diastolic 91-95 mm Hg) with<br />

definite hypertension (n = 306), the relative risk ratio <strong>of</strong> becoming a<br />

combined hypertensive associated with a 10 µg/g increase in patella Pb was<br />

1.23 (95% CI: 1.03, 1.48). Linear blood Pb and tibia Pb were not<br />

significant.<br />

Linear blood Pb is not indicated <strong>for</strong> blood pressure models due to strong<br />

likelihood <strong>of</strong> significant residual heteroscedasticity and non-normality.<br />

Relatively small sample size may have prevented tibia blood Pb significance<br />

in the Cox proportional hazard models.


AX6-132<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Den Hond et al.<br />

(2002)<br />

U.S.-NHANES <strong>II</strong>I<br />

1988-1994<br />

Gerr et al. (2002)<br />

U.S.-Spokane WA<br />

and area around<br />

Silver Valley ID<br />

1994<br />

4,685 white males, 5,138 white<br />

females, 1,761 black males, 2,197<br />

black females, from 20 yrs up. Logtrans<strong>for</strong>med<br />

blood Pb, systolic and<br />

diastolic blood pressure measured at<br />

survey time and analyzed with<br />

<strong>for</strong>ward, stepwise multiple<br />

regression with covariates.<br />

Avg age:<br />

White<br />

Male: 44.3 yrs<br />

Female: 46.2 yrs<br />

Black<br />

Male: 40.5 yrs<br />

Female: 41.5 yrs<br />

502 young people, age 19-29 yrs,<br />

53% female, nearly evenly divided<br />

into the Spokane group (no unusual<br />

childhood exposure) and the Silver<br />

Valley group, where a Pb smelter<br />

operated during their childhood.<br />

Multiple regression models <strong>of</strong><br />

systolic blood pressure and diastolic<br />

blood pressure. All covariates<br />

<strong>for</strong>ced into model as block with both<br />

linear blood Pb and tibia bone Pb in<br />

each model.<br />

Geometric mean<br />

(25th-75th percentile)<br />

blood Pb:<br />

White male mean 3.6 µg/dL<br />

(2.3-5.3)<br />

White female mean 2.1 µg/dL<br />

(1.3-3.4)<br />

Black male mean 4.2 µg/dL<br />

(2.7-6.5)<br />

Black female mean 2.3 µg/dL<br />

(1.4-3.9)<br />

Mean (SD) blood Pb only<br />

given stratified on tibia Pb<br />

category:<br />

Tibia


AX6-133<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Glenn et al. (2003)<br />

U.S.-New Jersey<br />

1994-1998<br />

496 males, mean (SD, range) age<br />

55.8 (7.4, 40-71) yrs, working or<br />

<strong>for</strong>merly working at a plant<br />

producing tetraethyl or tetramethyl<br />

Pb until 1991, were followed from<br />

10 mos to 3.5 yrs during which<br />

blood pressure was repeatedly<br />

tested. Blood Pb was tested only at<br />

baseline. Tibia Pb was tested in<br />

1991 (at the end <strong>of</strong> organic Pb<br />

production at the plant) and called<br />

“peak tibia Pb” and again during<br />

1997 (yr 3). Generalized estimating<br />

equations with an exchangeable<br />

correlation structure <strong>for</strong> repeated<br />

measurements were used <strong>for</strong> systolic<br />

and diastolic blood pressure. One<br />

group <strong>of</strong> covariates was <strong>for</strong>ced into<br />

the model as a block (age at<br />

baseline, race, BMI, indicator<br />

variable <strong>for</strong> technician, Pb variable<br />

(linear blood Pb, peak tibia Pb, and<br />

tibia Pb each tested separately),<br />

duration <strong>of</strong> follow up, and the<br />

interaction between the Pb variable<br />

and the duration term. Potential<br />

confounding variables were entered<br />

stepwise and retained in the model if<br />

significant. Alternate models not<br />

using linear time were constructed,<br />

using quartile <strong>of</strong> follow up time to<br />

avoid assuming a linear relationship<br />

<strong>of</strong> change in blood pressure with<br />

time.<br />

Arithmetic mean (SD, range)<br />

blood Pb at baseline:<br />

4.6 µg/dL (2.6, !1 to 20)<br />

Tibia Pb at yr 3:<br />

14.7 µg/g (9.4, !1.6 to 52)<br />

Peak tibia Pb:<br />

24.3 µg/g (18.1, !2.2 to<br />

118.8)<br />

Controlling <strong>for</strong> baseline age, BMI, antihypertensive medication use, smoking,<br />

education, technician and number <strong>of</strong> yrs to each blood pressure measurement,<br />

each 1 µg/dL increase in linear baseline blood Pb was associated with avg<br />

systolic blood pressure increase <strong>of</strong> 0.64 mm Hg/yr (95% CI: 0.14, 1.14),<br />

each 10 µg/g increase in yr 3 tibia Pb with an avg increase <strong>of</strong> 0.73 mm Hg/yr<br />

(95% CI: 0.23, 1.23), and each increase <strong>of</strong> 10 µg/g <strong>of</strong> peak tibia Pb with an<br />

avg increase <strong>of</strong> 0.61 mm Hg/yr (95% CI: 0.09, 1.13). Similar results were<br />

obtained using the follow up time quartile designation <strong>for</strong> systolic blood<br />

pressure with all subjects and with subjects not taking antihypertensive<br />

medications.<br />

This was one <strong>of</strong> the few studies using a prospective design and that used a<br />

statistical technique accounting <strong>for</strong> repeated measures. No justification given<br />

<strong>for</strong> using an exchangeable correlation structure instead <strong>of</strong> an alternate one.<br />

Only examined cortical bone Pb (tibia) and not trabecular bone Pb (patella or<br />

calcaneus). Linear blood Pb may not be indicated <strong>for</strong> use in blood Pb-blood<br />

pressure models. Stepwise modeling involves multiple testing <strong>of</strong> the same<br />

data set with no control <strong>for</strong> altered probabilities. No model diagnostics<br />

presented.


AX6-134<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Glenn et al.<br />

(2001)<br />

U.S.-New Jersey<br />

1996-1997<br />

213 males (92% white), mean (SD)<br />

age 58.0 (7.4) yrs, working or<br />

<strong>for</strong>merly working at a plant<br />

producing tetraethyl or tetramethyl<br />

Pb until 1991, were genotyped <strong>for</strong><br />

ATP1A2(5’) and ATP1A2(3’)<br />

polymorphism. ATPase is thought to<br />

play a role in regulating blood<br />

pressure and Pb inhibits its activity.<br />

Blood pressure, blood Pb, and tibia<br />

Pb were measured. Multiple linear<br />

regression models were used <strong>for</strong><br />

systolic and diastolic blood pressure.<br />

Logistic regression model was<br />

reported <strong>for</strong> hypertension<br />

(systolic >160 mm Hg,<br />

diastolic > 96 mm Hg, or taking<br />

antihypertensive medications).<br />

Covariate entry methods not<br />

specified, but were likely stepwise.<br />

Covariates <strong>for</strong> the blood pressure<br />

model were age, use <strong>of</strong><br />

antihypertensive medications,<br />

alcohol, smoking, season <strong>of</strong> yr, linear<br />

blood Pb, tibia Pb (the two Pb<br />

measures apparently tested<br />

separately), ATP1A2(5’) and<br />

ATP1A2(3’) polymorphism (each<br />

tested separately), and an interaction<br />

term between polymorphism and Pb.<br />

Covariates <strong>for</strong> the hypertension<br />

models were age, BMI, lifetime<br />

alcoholic drinks, linear blood Pb and<br />

tibia Pb, and polymorphism, each Pb<br />

measure and polymorphism tested<br />

separately.<br />

Arithmetic mean (SD, range)<br />

blood Pb:<br />

5.2 µg/dL (3.1, 1-20)<br />

Mean (SD) tibia Pb:<br />

16.3 µg/g (9.3)<br />

None <strong>of</strong> the relationships between the ATP1A2(5’) polymorphism and either blood<br />

or bone Pb or blood pressure were significant.<br />

The ATP1A2(3’) polymorphism was homogenous <strong>for</strong> the 10.5 kilobase allele<br />

(10.5/10.5) in 11 subjects, heterogeneous <strong>for</strong> the 10.5 and 4.3 kilobase allele<br />

(10.5/4.3) in 82 subjects, and heterogeneous (10.5/4.3) in 116 subjects. Prevalence<br />

<strong>of</strong> the 10.5 allele was significantly higher in blacks than in whites.<br />

Regression coefficients <strong>of</strong> 4.3/4.3 and 10.5/4.3 genotypes were not significantly<br />

different and all subsequent analyses compared the 10.5/10.5 genotype with the<br />

combined 4.3/4.3-10.5/4.3) genotype. The significant interaction between linear<br />

blood Pb and the 10.5/10.5 genotype showed that <strong>for</strong> every 1 µg/dL <strong>of</strong> blood Pb<br />

systolic blood pressure increased 5.6 mm Hg (95% CI: 1.2, 9.9) more than the blood<br />

pressure <strong>of</strong> the combined genotype group. Blood Pb range <strong>of</strong> the combined<br />

genotype group was twice that <strong>of</strong> the 10.5/10.5 group. When data were truncated to<br />

make blood Pb <strong>of</strong> both groups cover the same range, coefficients <strong>of</strong> the genotypelinear<br />

blood Pb interaction term did not change appreciably. Authors state that tibia<br />

Pb interacted with genotype on blood pressure but showed no data to estimate either<br />

type or size <strong>of</strong> effect. Diastolic blood pressure was not related to genotype, to Pb or<br />

to the interaction between Pb and genotype.<br />

Prevalence <strong>of</strong> hypertension (30% in total sample) was significantly higher among<br />

the 10.5/10.5 group (63.4 %) than among the combined group (28.3 %). Adjusting<br />

<strong>for</strong> age, BMI, and lifetime alcohol, the odds <strong>of</strong> hypertension in the 10.5/10.5 group<br />

were OR = 7.7 (95% CI: 1.9, 31.4) compared to the 4.3/4.3 group. The<br />

heterogeneous group was not significantly different from the 4.3/4.3 group.<br />

Linear blood Pb specification not indicated <strong>for</strong> blood Pb-blood pressure modeling.<br />

Examination <strong>of</strong> partial residual plot <strong>for</strong> systolic blood pressure and linear blood Pb<br />

shows typical heterogeneity <strong>of</strong> residuals as a function <strong>of</strong> predicted values. Thus,<br />

presented coefficients may be inefficient and biased. Only 9 subjects were<br />

homogenous <strong>for</strong> 10.5/10.5 in the multiple regression model. Only cortical bone Pb<br />

was tested, not trabecular bone Pb. Cortical bone Pb models not shown or<br />

quantitatively described. Blood Pb rounded to nearest unit µg/dL. Mixed organicinorganic<br />

Pb exposure. Relatively small sample size may have prevented detection<br />

<strong>of</strong> other significant effects. No model diagnostics described.


AX6-135<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference,<br />

Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Hu et al. (1996)<br />

U.S.-Boston-<br />

Normative<br />

Aging Study-<br />

VA<br />

1991-1994<br />

590 males (over 98% white), mean age<br />

around 67 yrs, divided into 146<br />

hypertensives (systolic >160 mm Hg,<br />

diastolic >95 mm Hg, or daily<br />

antihypertensive medication) and 444 nonhypertensives.<br />

Linear blood Pb, tibia and<br />

patella bone Pb added separately to logistic<br />

regression model containing <strong>for</strong>ced<br />

covariates <strong>of</strong> age, race, BMI, family history<br />

<strong>of</strong> hypertension, pack-yrs smoking, alcohol<br />

ingestion dietary sodium and calcium. Then,<br />

a backward elimination procedure starting<br />

with all covariates, including all Pb<br />

variables, resulted in a model in which only<br />

significant covariates were retained.<br />

Hypertensives:<br />

Arithmetic mean (SD)<br />

blood Pb:<br />

6.9 µg/dL (4.3)<br />

Mean tibia Pb:<br />

23.7 µg/g (14.0)<br />

Mean patella Pb:<br />

35.1 µg/g (19.5)<br />

Non-hypertensives:<br />

Arithmetic mean (SD)<br />

blood Pb:<br />

6.1 µg/dL (4.0)<br />

Mean tibia Pb:<br />

20.9 µg/g (11.4)<br />

Mean patella Pb:<br />

31.1 µg/g (18.3)<br />

Logistic regression model with all <strong>for</strong>ced covariates revealed no significant Pb<br />

effects when the three Pb variables were <strong>for</strong>ced into the model separately. After<br />

backward elimination, the only significant covariates left were BMI and family<br />

history <strong>of</strong> hypertension. Of all the Pb variables, only tibia Pb remained in the<br />

model. With each increase <strong>of</strong> 10 µg/g <strong>of</strong> tibia Pb, odds <strong>of</strong> being classified<br />

hypertensive rose (OR = 1.21; 95% CI: 1.04, 1.43).<br />

Stepwise regression, backward or <strong>for</strong>ward, involves multiple testing with the same<br />

data set, capitalizes on chance occurrence in the data set, and gives over-optimistic<br />

probability values. No model diagnostic testing reported.


AX6-136<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Korrick et al.<br />

(1999)<br />

U.S.-Boston-Nurse<br />

Health Study<br />

1993-1995<br />

Morris et al. (1990)<br />

U.S.-sampled from<br />

general population<br />

around Portland,<br />

OR responding to<br />

ads to participate in<br />

clinical trials <strong>of</strong><br />

nonpharmacological<br />

management <strong>of</strong><br />

blood pressure.<br />

1984-1989?<br />

284 women, from 47-74 yrs, mean age<br />

(SD) 58.7 (7.2), were divided into 97<br />

cases (systolic ∃140 mm Hg,<br />

diastolic ∃90 mm Hg, or physiciandiagnosed<br />

hypertension) and<br />

195 controls. Controls were further<br />

classified as low normal<br />

(121/75 mm Hg). Three ordinal<br />

regression models were constructed,<br />

each containing either blood Pb, tibia Pb<br />

or patella Pb with <strong>for</strong>ced entry <strong>of</strong> all<br />

other covariates. A final backwards<br />

elimination ordinal regression model<br />

started with all covariates, including all<br />

Pb variables, excluding each until only<br />

significant variables were left.<br />

Interactions were tested in the final<br />

model between patella Pb and alcohol<br />

use, age, and menopausal status.<br />

145 males and 106 females, 73% with<br />

arterial pressures >105 mm Hg,<br />

provided blood pressure measurements<br />

once a wk over four consecutive wks.<br />

Blood <strong>for</strong> Pb analysis was collected<br />

during this period. Stepwise multiple<br />

regression was used to construct<br />

separate models <strong>of</strong> systolic and diastolic<br />

blood pressure stratified by sex.<br />

Covariates available to be entered were<br />

age, BMI, dietary calcium and “other<br />

nutrient intakes,” ionized serum<br />

calcium, erythrocyte protoporphyrin and<br />

natural log trans<strong>for</strong>med blood Pb.<br />

Mean blood Pb (SD, range):<br />

3.1 µg/dL (2.3,


AX6-137<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Nash et al. (2003)<br />

U.S.-NHANES <strong>II</strong>I<br />

1988-1994<br />

1084 premenopausal and 633<br />

postmenopausal women, from 40<br />

to 59 yrs. Multiple linear<br />

regression models with<br />

covariates, including linear blood<br />

Pb, entered as a block <strong>for</strong> systolic<br />

and diastolic blood pressure.<br />

Logistic regression models with<br />

same covariates and Pb quartile<br />

added last <strong>for</strong> hypertension.<br />

Mean (range) blood Pb by<br />

Pb quartile:<br />

1st quartile 1.0 µg/dL<br />

(0.5-1.6)<br />

2nd quartile 2.1 µg/dL<br />

(1.7-2.5)<br />

3rd quartile 3.2 µg/dL<br />

(2.6-3.9)<br />

4th quartile 6.4 µg/dL<br />

(4.0-31.1)<br />

Linear blood Pb was entered last after <strong>for</strong>cing in age, race/ethnicity, alcohol use,<br />

cigarette smoking, BMI, and kidney function (serum creatinine) in multiple regression<br />

models <strong>for</strong> all women and women stratified by menopause status <strong>for</strong> systolic and<br />

diastolic blood pressure. Pb quartile was added to logistic regression models <strong>of</strong><br />

hypertension (systolic ∃140 mm Hg, diastolic ∃90 mm Hg or taking antihypertensive<br />

medication with the same covariates as the blood pressure models, in all women and<br />

stratified by menopausal status. Tested additional models in which women treated <strong>for</strong><br />

hypertension were excluded from models. All models were adjusted <strong>for</strong> sample<br />

design and weighting.<br />

Each increase <strong>of</strong> 1 µg/dL <strong>of</strong> blood Pb was significantly associated with a 0.32 mm Hg<br />

(95% CI: 0.01, 0.63) increase <strong>of</strong> systolic blood pressure and a 0.25 mm Hg (95% CI:<br />

0.07, 0.43) increase <strong>of</strong> diastolic blood pressure in all women without respect to<br />

menopausal status. In analyses stratified by menopausal status, only postmenopausal<br />

women showed a significant blood Pb effect. For each 1 µg/dL increase <strong>of</strong> blood Pb<br />

was associated with significantly increased diastolic blood pressure <strong>of</strong> 0.14 (95% CI:<br />

−0.11, 0.39 sic.) only in postmenopausal women.<br />

Referenced to the 1st blood Pb quartile, no other quartile showed significantly<br />

increased odds <strong>for</strong> hypertension in all subjects or in subjects stratified by menopausal<br />

status. With further analyses stratified by systolic and diastolic hypertension without<br />

women taking antihypertensive medications, in the combined group <strong>of</strong> pre and<br />

postmenopausal women the odds <strong>of</strong> diastolic hypertension were significant when the<br />

4th Pb quartile was compared to the 1st quartile (OR = 3.4 [95% CI: 1.3, 8.7]). In a<br />

model <strong>of</strong> only postmenopausal women untreated <strong>for</strong> hypertension, odds <strong>of</strong> diastolic<br />

hypertension were significantly increased in the higher three quartiles <strong>of</strong> blood Pb<br />

(OR = 4.6 [95% CI: 1.1, 19.2], OR = 5.9 [95% CI: 1.5, 23.1], OR = 8.1 [95% CI:<br />

2.6, 24.7], respectively) and odds <strong>of</strong> systolic hypertension were significant only <strong>for</strong> the<br />

two middle Pb quartiles (OR = 3.0 [95% CI: 1.3, 6.9], OR = 2.7 [95% CI: 1.2, 6.2],<br />

respectively).<br />

Linear blood Pb is suspect in linear regression models <strong>of</strong> blood pressure as it is<br />

usually associated with biased and inefficient estimation <strong>of</strong> Pb coefficients due to<br />

probable heteroscedasticity and non-normal distribution <strong>of</strong> residuals. No model<br />

diagnostics were reported. No statistical testing <strong>for</strong> differences in Pb coefficients<br />

according to strata. Nine stratified models overall. Not all stated significance levels<br />

and standard errors in the blood pressure model table corresponded <strong>for</strong> certain<br />

variables.


AX6-138<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Proctor et al.<br />

(1996)<br />

U.S.-Boston-<br />

Normative Aging<br />

Study (VA)<br />

1992-1993<br />

798 men from 17 to 44 yrs.<br />

Multiple linear regression models<br />

<strong>of</strong> natural log blood Pb on<br />

systolic and diastolic blood<br />

pressure. All covariates <strong>for</strong>ced<br />

into model.<br />

Arithmetic mean (SD,<br />

range) blood Pb:<br />

6.5 µg/dL (4.0, 0.5-35)<br />

Natural log blood Pb, age, age-squared, BMI, adjusted dietary calcium, exercise,<br />

indicator variables <strong>for</strong> current and <strong>for</strong>mer smoker, daily alcohol consumption, sitting<br />

heart rate, and hematocrit were entered into multiple regression models without regard<br />

<strong>for</strong> significance.<br />

Increased diastolic, but not systolic, blood pressure was significantly associated with<br />

increased blood Pb. Each natural log increase in blood Pb was associated with a<br />

1.2 mm Hg (95% CI: 0.1, 2.2) increase in diastolic blood pressure.<br />

Interactions between dietary calcium and blood Pb on blood pressure were not<br />

significant. Further analyses stratified on use <strong>of</strong> antihypertensive medication and<br />

those older than or equal to 74 yrs still revealed significant blood Pb-diastolic blood<br />

pressure relationships.<br />

Blood Pb in over half the study group (n = 410) was determined by analyzing<br />

previously frozen erythrocytes collected several yrs prior to the blood pressure<br />

measurements used in the study and corrected by using hematocrit values also<br />

measured when blood was originally collected. Combining both groups means that<br />

nearly half the group was tested <strong>for</strong> the effects <strong>of</strong> blood Pb on blood pressure<br />

measured at the same time, the other half measured several yrs apart. There was no<br />

correction in models <strong>for</strong> this potential effect. The effect <strong>of</strong> taking antihypertensive<br />

medication could have been assessed in a single model by using an indicator variable.<br />

No statistical testing <strong>for</strong> the effects <strong>of</strong> stratification on the blood Pb-blood pressure<br />

relationship. No model diagnostics.


AX6-139<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Rothenberg et al.<br />

(1999)<br />

U.S.-Los Angeles<br />

1995-1998<br />

Rothenberg et al.<br />

(2002a)<br />

U.S.-Los Angeles<br />

1995-2001<br />

1188 immigrants and 439 nonimmigrants,<br />

from 15 to 43 yrs, all women in 3rd<br />

trimester <strong>of</strong> pregnancy. Multiple<br />

regression models <strong>of</strong> natural log blood Pb<br />

on systolic and diastolic blood pressure<br />

with all covariates <strong>for</strong>ced into models.<br />

Covariates selected from larger set based<br />

on significant univariate or bivariate tests.<br />

668 women, 15 to 44 yrs, studied in 3rd<br />

trimester pregnancy and again a mean <strong>of</strong><br />

10 wks postpartum. Exclusion criteria<br />

were diabetes, renal or cardiovascular<br />

disease, extreme postnatal obesity<br />

(BMI >40), and subjects using stimulant<br />

drugs. Multiple linear regression models<br />

<strong>of</strong> natural log blood Pb, tibia and<br />

calcaneus Pb on systolic and diastolic<br />

blood pressure with all covariates and all<br />

Pb variables <strong>for</strong>ced into model. Separate<br />

models <strong>for</strong> 3rd trimester and postpartum,<br />

excluding all women with hypertension<br />

(see below) during each specific period.<br />

Logistic regression <strong>for</strong> hypertension<br />

(systolic ∃140 mm Hg or diastolic ∃90),<br />

specific to 3rd trimester and postpartum<br />

periods with the same covariates and Pb<br />

variables.<br />

Geometric mean (SD)<br />

blood Pb:<br />

Immigrants: 2.3 µg/dL<br />

(1.4)<br />

Non-immigrants:<br />

1.9 µg/dL (1.3)<br />

Geometric mean blood<br />

Pb (SD):<br />

3rd trimester:<br />

1.9 µg/dL (1.7)<br />

Postpartum: 2.3 µg/dL<br />

(2.0)<br />

Tibia mean Pb (SD):<br />

8.0 µg/g (11.4)<br />

Calcaneus mean Pb<br />

(SD):<br />

10.7 µg/g (11.9)<br />

Natural log blood Pb, age, BMI, c<strong>of</strong>fee drinking, iron supplementation, and job stress<br />

were entered as a block without regard to significance in linear multiple regression<br />

models <strong>of</strong> systolic and diastolic blood pressure stratified by immigration status.<br />

Increased blood Pb was significantly associated with increased blood pressure only in<br />

immigrants. Each natural log unit increase in blood Pb was associated with a<br />

1.7 mm Hg (95% CI: 0.7, 2.8) increase in systolic blood pressure and a 1.5 mm Hg<br />

(95% CI: 0.5, 1.9) increase in diastolic blood pressure in immigrants.<br />

Used and reported model diagnostic tests, as evidenced by the use <strong>of</strong> standard error<br />

calculations robust to residual heteroscedasticity. Stated reasons <strong>for</strong> stratification on<br />

immigrant status were significant differences between the two groups in blood Pb,<br />

blood pressure, age, BMI, and education. Did not statistically test difference in Pb<br />

coefficients between the immigration strata. Did not correct <strong>for</strong> potential non-linearity<br />

in age effects on blood pressure.<br />

Multiple linear regression models <strong>for</strong> normotensives adjusted <strong>for</strong> postnatal<br />

hypertension (3rd trimester model only), BMI, age, parity, smoking, alcohol,<br />

immigrant status, and educational level plus all three Pb indices. Only calcaneus Pb<br />

was associated with blood pressure in 3rd trimester models. Every 10 µg/g increase in<br />

calcaneus Pb was associated with 0.70 mm Hg (95% CI: 0.04, 1.36) increase in<br />

systolic blood pressure and a 0.54 mm Hg (95% CI: 0.01, 1.08) increase in diastolic<br />

blood pressure. In postpartum models, natural log blood Pb was the only variable<br />

statistically associated with blood pressure. Every natural log unit increase in blood<br />

Pb was associated with !1.52 mm Hg (95% CI: !2.83, !0.20) decrease in systolic<br />

blood pressure and a −1.67 mm Hg (95% CI: !2.85, !0.50) decrease in diastolic blood<br />

pressure.<br />

In logistic models, only calcaneus Pb was significantly associated with increased odds<br />

<strong>for</strong> hypertension. Each 10 µg/g increase in calcaneus Pb was associated with an OR =<br />

1.86 (95% CI: 1.04, 3.32) <strong>of</strong> 3rd trimester hypertension. None <strong>of</strong> the Pb variables<br />

was associated with postpartum hypertension.<br />

Models did not use age-squared covariate. Models did not use repeated measures<br />

statistics. No statistical comparisons between 3rd trimester and postpartum models.<br />

Model diagnostic tests reported.


AX6-140<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Schwartz et al.<br />

(2000c)<br />

U.S.-Eastern<br />

1996-1997<br />

543 mostly <strong>for</strong>mer organolead<br />

workers, predominantly white<br />

(92.8%), at a tetraethyl/tetramethyl<br />

plant, mean (SD) [range] age 7.6 (7.6)<br />

[41.7-73.7] yrs had blood Pb, DMSAchelatable<br />

Pb (4-hr. urinary Pb<br />

excretion after a single 10 mg/kg dose<br />

<strong>of</strong> DMSA) measured <strong>for</strong> modeling<br />

systolic and diastolic blood pressure<br />

and hypertension (systolic >160<br />

mm Hg or diastolic ∃96 mm Hg or<br />

taking antihypertensive medications.<br />

Tibia Pb ~2 yrs later was also used as<br />

a Pb index. For blood pressure, linear<br />

multiple regression with backward<br />

elimination <strong>of</strong> non-significant<br />

covariates or covariates that “had<br />

important influence on the coefficients<br />

<strong>for</strong> the Pb-dose terms.” Each Pb<br />

variable was tested in a separate<br />

model. Potential covariates <strong>for</strong> these<br />

models were age, BMI, current<br />

tobacco use, and current use <strong>of</strong><br />

antihypertensive medications. Other<br />

models were constructed taking out<br />

those subjects using antihypertensive<br />

medications. Both linear and linear +<br />

quadratic blood and tibia Pb terms<br />

were tested. Logistic regression<br />

analyses were used to test the effect <strong>of</strong><br />

the Pb variables on hypertension,<br />

controlling <strong>for</strong> age, diabetes, lifetime<br />

alcohol consumption, and BMI.<br />

Logistic models also tested each Pb<br />

measure in interaction with age.<br />

Blood Pb arithmetic<br />

mean (SD, range):<br />

4.6 µg/dL (2.6, 1<br />

to 20)<br />

DMSA-chelatable Pb<br />

mean (SD, range):<br />

19.0 µg (16.6, 1.2<br />

to 136)<br />

Tibia Pb mean (SD,<br />

range): 14.4 µg/g<br />

(9.3, !1.6 to 52)<br />

Adjusting <strong>for</strong> age, BMI, current smoking, and current use <strong>of</strong> antihypertensive medications,<br />

each 1 µg/dL increase in blood Pb-squared was significantly associated with 0.189 mm Hg<br />

(95% CI: 0.087, 0.330) increase in systolic blood pressure with three outliers removed.<br />

With the same covariates, each 1 µg/dL increase in linear blood Pb was significantly<br />

associated with 0.310 mm Hg (95% CI: 0.028, 0.592) in diastolic blood pressure taken<br />

over a 2-yr period (n = 525). No other Pb variables were significant.<br />

For the hypertension models, only the interaction <strong>of</strong> linear blood Pb by age was significant,<br />

with subjects showing significant decrease in odds ratio <strong>of</strong> hypertension with every joint<br />

increase <strong>of</strong> 1 µg/dL blood Pb and 1 yr increase in age (linear blood Pb X age OR = 0.98;<br />

[95% CI: 0.97, 0.99]). The interaction suggested a concentration-response relationship<br />

between linear blood Pb and hypertension only up to ~58 yrs <strong>of</strong> age.<br />

Authors note that blood pressure findings “were not affected by exclusion or inclusion <strong>of</strong><br />

subjects using antihypertensive medications,” but do not present either the data or the<br />

statistical tests to evaluate that conclusion. No other model diagnostics were reported.<br />

Although blood Pb was also modeled as a quadratic Pb term <strong>for</strong> systolic blood pressure, no<br />

analysis was shown <strong>for</strong> non-linear blood Pb terms <strong>for</strong> diastolic blood pressure.<br />

Trabecular bone Pb was not tested, though other studies indicate that it is a better Pb index<br />

than cortical Pb <strong>for</strong> cross-sectional blood pressure and hypertension study.<br />

Although the backward procedures described could have resulted in less than the full set <strong>of</strong><br />

considered covariates entering the models, all model presentations were limited to showing<br />

the Pb coefficients and all models indicated in a footnote that the Pb coefficients were<br />

adjusted <strong>for</strong> each possible covariate <strong>for</strong> that model. While this is possible with the short<br />

list <strong>of</strong> covariates, given the 14 models presented one might expect to see at least one model<br />

where one <strong>of</strong> the covariates did not remain.


AX6-141<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Schwartz (1995)<br />

15 prior U.S. and<br />

European studies<br />

published between<br />

1985 and 1993<br />

Schwartz (1991)<br />

NHANES <strong>II</strong><br />

U.S.<br />

1976-1980<br />

Total subjects not specified, men and<br />

women ages 18 to 74 yrs. Random<br />

effects meta-analysis with inverse<br />

variance weighting <strong>of</strong> Pb-blood<br />

pressure coefficients from each study.<br />

Sensitivity analysis per<strong>for</strong>med by<br />

dropping study with largest or smallest<br />

effect.<br />

Under 10,000 subjects (exact number<br />

not reported), males and females, aged<br />

25 to 74 yrs <strong>for</strong> left ventricular<br />

hypertrophy results with logistic<br />

regression. Linear blood Pb used <strong>for</strong><br />

LVH. For blood pressure results,<br />

multiple linear regressions stratified by<br />

sex, with one block <strong>of</strong> variables<br />

<strong>for</strong>ced, another block <strong>of</strong> variables<br />

entered with stepwise regression, aged<br />

6 mos to 74 yrs, exact number not<br />

given. Natural log blood Pb used <strong>for</strong><br />

linear regression. Both logistic and<br />

linear regressions adjusted <strong>for</strong> survey<br />

design.<br />

Blood Pb levels not<br />

stated.<br />

No blood Pb<br />

descriptive data<br />

given.<br />

Each doubling <strong>of</strong> natural log blood Pb level was associated with an increase <strong>of</strong> 1.25<br />

mm Hg (95% CI: 0.87, 1.63) systolic blood pressure. Sensitivity analysis showed<br />

negligible change in meta-analysis coefficient. Concluded that adding newer studies<br />

would not change calculated coefficient. Noted Pb-blood pressure slope was larger at<br />

lower Pb levels than at higher Pb levels.<br />

The study only analyzed systolic, not diastolic, blood pressure. Superseded by<br />

Nawrot et al. (2002).<br />

Used logistic regression to study Pb effect on left ventricular hypertrophy (LVH)<br />

determined by a combination <strong>of</strong> electrocardiogram parameters and body habitus,<br />

controlling <strong>for</strong> age, race, and sex. Every 10 µg/dL blood Pb increase was associated<br />

with increased odds <strong>of</strong> LVH <strong>of</strong> 1.33 (95% CI: 1.20, 1.47). Interaction terms <strong>for</strong> race<br />

by blood Pb and sex by blood Pb were not significant.<br />

Blood pressure models stratified by sex always included BMI, age and age-squared,<br />

race, and natural log blood Pb. Male blood pressure model also included family<br />

history <strong>of</strong> hypertension, cholesterol, height, cigarette use, serum zinc, and tricep skin<br />

fold. Female model also included serum zinc, family history <strong>of</strong> hypertension, tricep<br />

skin fold, and cholesterol. Every 1 natural log unit <strong>of</strong> blood Pb increase was<br />

associated with an increase in diastolic blood pressure <strong>of</strong> 2.93 mm Hg (95% CI: 0.93,<br />

4.98) in males and 1.64 mm Hg (95% CI: 0.27, 3.01). Used interaction terms <strong>for</strong><br />

race-blood Pb and sex-blood Pb in a non-stratified model and found no significant<br />

effect <strong>of</strong> race or sex on the blood Pb-blood pressure coefficient.<br />

Incomplete reporting <strong>of</strong> subject size <strong>for</strong> models and <strong>for</strong> descriptive statistics <strong>for</strong> all<br />

variables in models. Tested both linear and log trans<strong>for</strong>med Pb in preliminary testing.<br />

Found log Pb had lower probability values than linear Pb <strong>for</strong> blood pressure, and<br />

linear Pb had lower probability values than log Pb <strong>for</strong> LVH. No testing <strong>of</strong> significant<br />

difference between the two blood Pb specifications. No model diagnostics reported.<br />

Only reported diastolic blood pressure results.


AX6-142<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Sokas et al. (1997)<br />

U.S.-Maryland<br />

1989-1990<br />

Sorel et al. (1991)<br />

U.S.-NHANES <strong>II</strong><br />

1976-1980<br />

264 active or retired construction<br />

workers, over 99% men, who were not<br />

involved in Pb work at time <strong>of</strong> testing,<br />

mean age (range) 43 yrs (18-79).<br />

Multiple regression modeling <strong>of</strong><br />

systolic and diastolic blood pressure<br />

adjusted <strong>for</strong> covariates <strong>of</strong> BMI, age,<br />

hematocrit, erythrocyte<br />

protoporphyrin, race, linear blood Pb<br />

and a race-linear blood Pb interaction.<br />

Method <strong>of</strong> covariate entry not made<br />

explicit, though it appeared to be<br />

<strong>for</strong>ced.<br />

2056 females, 2044 males, 473 blacks<br />

and 3627 whites, from 18-74 yrs, were<br />

used in survey design and weight<br />

adjusted multiple linear regressions<br />

stratified by sex, with separate models<br />

<strong>for</strong> systolic and diastolic blood<br />

pressure. Covariates included age,<br />

BMI, race, and poverty income ratio<br />

and linear blood Pb. Method <strong>of</strong><br />

covariate entry not specified but may<br />

have been <strong>for</strong>ced. Different covariate<br />

groups were used <strong>for</strong> different models.<br />

Primary test <strong>for</strong> the effect <strong>of</strong> race on<br />

the Pb-blood pressure relationship was<br />

to note the change in the race<br />

coefficient in models with and without<br />

the linear blood Pb variable.<br />

Mean blood Pb<br />

(range): 8.0 µg/dL<br />

(1-30)<br />

Age-adjusted<br />

arithmetic mean<br />

blood Pb:<br />

Black female:<br />

13.2 µg/dL (no<br />

variance in<strong>for</strong>mation<br />

<strong>for</strong> any blood Pb)<br />

White female:<br />

12.1 µg/dL<br />

Black male:<br />

20.1 µg/dL<br />

White male:<br />

16.8 µg/dL<br />

Linear blood Pb was not significantly related to either systolic or diastolic blood<br />

pressure, though the race by linear blood Pb interaction was marginally significant<br />

(p = 0.09). Each 1 µg/dL increase in blood Pb increased black systolic blood pressure<br />

0.86 mm Hg (no SE or 95% CI reported) more than white systolic blood pressure.<br />

Linear blood Pb term may not be appropriate. Small sample compromises<br />

interpretation <strong>of</strong> non-significant results. By using erythrocyte protoporphyrin and<br />

blood Pb in the same model, these two measures <strong>of</strong> Pb exposure may have been<br />

confounded. Incomplete reporting <strong>of</strong> procedures and results. No model diagnostic<br />

tests reported.<br />

Linear blood Pb was significantly related only to diastolic blood pressure in males,<br />

adjusting <strong>for</strong> age and BMI. For every 1 µg/dL blood Pb increase diastolic blood<br />

pressure increased 0.13 mm Hg (95% CI: 0.04, 0.21). Adding race to the model with<br />

and without linear blood Pb terms did not appear to change the race coefficient.<br />

Adding poverty index to the models with and without blood Pb produced the same<br />

small change in poverty index coefficient.<br />

Linear blood Pb may not be appropriate. Only confidence intervals were used to<br />

assess the significance <strong>of</strong> changes in race and poverty index coefficients across<br />

models with and without Pb, instead <strong>of</strong> using interaction terms <strong>of</strong> these two variables<br />

with Pb. Incomplete reporting <strong>of</strong> procedures and results. No model diagnostic tests<br />

reported.


AX6-143<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Sharp et al. (1990)<br />

U.S.-San<br />

Francisco, CA<br />

1986<br />

After exclusion <strong>of</strong> subjects under<br />

treatment <strong>for</strong> hypertension, 249 male<br />

bus drivers, 132 <strong>of</strong> whom were black,<br />

age from 31 to 65 yrs, were used in<br />

race stratified multiple regression<br />

models <strong>of</strong> systolic and diastolic blood<br />

pressure with covariate <strong>for</strong>ced entry <strong>of</strong><br />

age, age-squared, BMI, caffeine use,<br />

tobacco use, and natural log blood Pb.<br />

Alcohol use was added in other<br />

models. Other models stratified by<br />

caffeine use.<br />

Geometric mean (range)<br />

blood Pb:<br />

Black males: 6.5 µg/dL (3-21)<br />

Non-black males:<br />

6.2 µg/dL (2-15)<br />

Significant log blood Pb effects were noted in blacks. In models excluding alcohol<br />

use, <strong>for</strong> every one natural log unit increase <strong>of</strong> blood Pb, systolic blood pressure rose<br />

7.53 mm Hg (95% CI: 0.86, 14.2) and diastolic blood pressure rose 4.72 mm Hg<br />

(95% CI: 0.15, 9.29). Stratified by infrequent/frequent caffeine users, only black<br />

infrequent caffeine users showed a significant response to blood Pb. For every one<br />

natural log unit increase <strong>of</strong> blood Pb, systolic blood pressure rose 16.69 mm Hg (95%<br />

CI: 3.83, 29.5) and diastolic blood pressure rose 10.43 mm Hg (95% CI: 1.26, 19.6).<br />

Non-black blood pressure was decreased with increasing natural log Pb but was<br />

marginally significant. In all non-black subjects, <strong>for</strong> every unit increase in natural log<br />

blood Pb, systolic blood pressure decreased −5.71 mm Hg (95% CI: −12.0, 0.6).<br />

Addition <strong>of</strong> alcohol to the models decreased all coefficients a small amount.<br />

Progressive addition <strong>of</strong> age, BMI, caffeine, and tobacco, in that order, progressively<br />

increased the coefficient <strong>of</strong> natural log blood Pb in models <strong>of</strong> systolic and diastolic<br />

blood pressure in blacks. Removal <strong>of</strong> two black outliers did not materially change the<br />

results <strong>for</strong> blacks.<br />

No statistical tests <strong>for</strong> comparing stratified models, models with and without caffeine<br />

use, effect <strong>of</strong> progressive addition <strong>of</strong> covariates, or addition <strong>of</strong> alcohol. Influence<br />

diagnostics reported <strong>for</strong> detecting the two outlying subjects. No other diagnostic tests<br />

reported. Small differences in text and table reports <strong>of</strong> the same coefficients. Small<br />

sample size limits interpretation <strong>of</strong> non-significant results.


AX6-144<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Tepper et al.<br />

(2001)<br />

U.S.-Cincinnati,<br />

OH<br />

After 1991 to<br />

be<strong>for</strong>e 2001<br />

43 females and 57 males, current or<br />

<strong>for</strong>mer workers at a Pb-acid battery<br />

factory, between 36 and 73 yrs <strong>of</strong> age,<br />

with at least 10 yrs working in battery<br />

production, participated. Multivariate<br />

regression models and logistic<br />

regression models were constructed to<br />

assess Pb exposure effect on outcome<br />

(hypertension: >140/90 mm Hg and<br />

>160/95 mm Hg or taking<br />

antihypertensive meds; diastolic and<br />

systolic blood pressure, and left<br />

ventricular mass/body surface area<br />

(g/m 2 ). Echocardiograms were used to<br />

determine left ventricular mass.<br />

Variables used to adjust all models<br />

were age, BMI, sex, and family history<br />

<strong>of</strong> hypertension.<br />

Plant blood Pb records were<br />

used to calculate cumulative<br />

blood Pb index (CBLI) used as<br />

a tertile measure, a linear<br />

continuous measure, and a log<br />

trans<strong>for</strong>med measure.<br />

CBLI µg/dL-yr<br />

1st tertile: 138-504<br />

2nd tertile: 505-746<br />

3rd tertile: 747-1447<br />

Time-avgd blood Pb TABL)<br />

was treated the same way:<br />

TABL µg/dL<br />

1st tertile: 12-25<br />

2nd tertile: 26-33<br />

3rd tertile: 34-50<br />

No odds ratios were given <strong>for</strong> hypertension and any Pb variable <strong>for</strong> hypertension<br />

defined as >140/90 mm Hg but ORs were claimed not significant. Odds ratios were<br />

2.71 and 1.44 <strong>for</strong> the 3rd tertile CBLI and TABL Pb measures compared to 1st tertile,<br />

apparently significant, but no probabilities, SEs or CIs given.<br />

With the 81 subjects not taking anti-hypertensive meds, neither CBLI tertile nor<br />

TABL tertile were significantly associated with either diastolic or systolic blood<br />

pressure (coefficients, SEs or 95% CIs not given). Using log trans<strong>for</strong>med CBLI<br />

probability <strong>of</strong> a positive association with diastolic blood pressure was 0.06. Using log<br />

trans<strong>for</strong>med TABL, probability <strong>of</strong> a positive association with diastolic blood pressure<br />

was 0.10. No coefficients, SEs, or CIs given.<br />

Left ventricular mass adjusted <strong>for</strong> body surface area was not significantly related to<br />

any Pb measure. No coefficients, SEs or CIs given.<br />

Despite the certainty <strong>of</strong> the authors that “we found no convincing evidence <strong>of</strong> an<br />

association…”, the very low power <strong>of</strong> this study gives certainty to none <strong>of</strong> the<br />

findings. Very poor reporting <strong>of</strong> results further reduces the possibility <strong>of</strong> evaluation.<br />

No model diagnostic testing was reported.


AX6-145<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Vupputuri et al.<br />

(2003)<br />

U.S.-NHANES <strong>II</strong>I<br />

1988-1994<br />

5188 white women, 2300 black<br />

women, 5360 white men, and 2104<br />

black men, aged 18 yrs and older.<br />

Survey adjusted multiple linear and<br />

logistic regression were used to assess<br />

linear blood Pb effect on systolic and<br />

diastolic blood pressure and<br />

hypertension in race and sex stratified<br />

models.<br />

Arithmetic mean (SD)<br />

blood Pb:<br />

White women 3.0 µg/dL (7.2)<br />

Black women 3.4 µg/dL (4.8)<br />

White men 4.4 µg/dL (7.3)<br />

Black men 5.4 µg/dL (9.3)<br />

Multiple linear regression models were all adjusted <strong>for</strong> age, education, BMI, alcohol<br />

consumption, leisure time physical activity, dietary sodium and potassium, and total<br />

calories. Only black women and men showed significant linear Pb effects. Every<br />

1 µg/dL increase in blood Pb was associated with an increase <strong>of</strong> 0.47 mm Hg (95%<br />

CI: 0.14, 0.80) in systolic and 0.32 mm Hg (95% CI: 0.11, 0.54) diastolic blood<br />

pressure in black women, and 0.25 mm Hg (95% CI: 0.06, 0.44) systolic and 0.19<br />

mm Hg (95% CI: 0.02, 0.36) diastolic blood pressure in black men.<br />

Odds <strong>of</strong> hypertension (systolic ∃140 mm Hg, diastolic ∃90 mm Hg, or taking<br />

antihypertensive medication) significantly increased <strong>for</strong> every SD (3.3 µg/dL) <strong>of</strong><br />

blood Pb level in black women (OR = 1.39 [95% CI: 1.21, 1.61]), in white women<br />

(OR = 1.32 [95% CI: 1.14, 1.52]), in black men (OR = 1.26 [95% CI: 0.99, 1.19]),<br />

but not in white men.<br />

Linear blood Pb terms are usually not appropriate in multiple linear regression models<br />

<strong>of</strong> blood pressure. Furthermore, they reported their results in terms <strong>of</strong> change in 1 SD<br />

unit <strong>of</strong> Pb. Linear SD <strong>of</strong> Pb is incorrect <strong>for</strong> log-normal distributions <strong>of</strong> blood Pb. No<br />

model diagnostic tests reported. Discrepancy between Methods report <strong>of</strong> race-Pb and<br />

sex-Pb interactions in simple, not multiple, analyses, but Results reports significant<br />

interactions <strong>for</strong> race-Pb and sex-Pb in multiple regression models <strong>for</strong> both linear<br />

regression and logistic regression models, without showing the results <strong>of</strong> the<br />

interaction analyses. The probability <strong>of</strong> the stated interactions (p < 0.001) appears<br />

extremely low, given the degree <strong>of</strong> 95% CI overlap in Pb coefficients among the<br />

stratified models. No model diagnostics reported.


AX6-146<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Bost et al. (1999)<br />

Europe-England-<br />

Health Survey <strong>for</strong><br />

England<br />

1995<br />

2763 women and 2563 men from a multistage<br />

stratified probability survey<br />

representative <strong>of</strong> the English population<br />

living in private residences, mean (SE) age<br />

<strong>for</strong> men 47.5 yrs (0.34) and <strong>for</strong> women 47.7<br />

yrs (0.33) (all subjects 16 yrs and older)<br />

were used in an analysis <strong>of</strong> blood Pb<br />

association with systolic and diastolic blood<br />

pressure. Stepwise multiple regression<br />

analysis were used testing natural log blood<br />

Pb against common log systolic blood<br />

pressure and non-trans<strong>for</strong>med diastolic<br />

blood pressure, with the following potential<br />

covariates: age, BMI, smoking status,<br />

region <strong>of</strong> residence, social class, and<br />

alcohol consumption. Models were<br />

stratified by sex, with and without<br />

adjustment <strong>for</strong> alcohol, including or<br />

excluding those taking antihypertensive<br />

medications.<br />

Geometric mean blood Pb:<br />

Men: 3.7 µg/dL (no stated<br />

measure <strong>of</strong> variance)<br />

Women: 2.6 µg/dL<br />

(no stated measure <strong>of</strong><br />

variance<br />

Model tables presented only standardized variable coefficients. The most<br />

consistent results were reported on common log Pb association with men’s<br />

diastolic blood pressure. Every doubling <strong>of</strong> blood Pb was significantly<br />

associated with an increase <strong>of</strong> 0.78 mm Hg (95% CI: 0.01, 1.55) diastolic<br />

blood pressure, adjusted <strong>for</strong> age, log BMI, and alcohol, but excluding men<br />

on antihypertensive medication. Every doubling <strong>of</strong> blood Pb was<br />

significantly associated with an increase <strong>of</strong> 0.88 mm Hg (95% CI: 0.13,<br />

1.63) in the same model with men on antihypertensive medication. Every<br />

doubling <strong>of</strong> blood Pb was significantly associated with an increase <strong>of</strong> 0.96<br />

mm Hg (95% CI: 0.23, 1.70) in the same model excluding men on<br />

antihypertensive medication and not adjusting <strong>for</strong> alcohol. Every doubling<br />

<strong>of</strong> blood Pb was significantly associated with an increase <strong>of</strong> 1.07 mm Hg<br />

(95% CI: 0.37, 1.78) including men taking antihypertensive medication and<br />

not accounting <strong>for</strong> alcohol. None <strong>of</strong> the multiple regression models had<br />

significant Pb terms <strong>for</strong> women.<br />

This report was not sufficiently detailed. Stepwise regression modeling is<br />

prone to the usual pitfalls. Survey design adjusted analysis not used. Pb<br />

was not entered in models in which criterion probability was exceeded<br />

(p > 0.05). No rationale given <strong>for</strong> stratifying. No testing <strong>of</strong> differences<br />

among Pb coefficients <strong>for</strong> the different models was made, which would have<br />

been especially valuable to compare models adjusted and not adjusted <strong>for</strong><br />

alcohol use. No explanation <strong>for</strong> using log systolic blood pressure as<br />

dependent variable. No model diagnostics reported.


AX6-147<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Fewtrell et al.<br />

(2004)<br />

Global<br />

1988-2002<br />

Using available global figures on<br />

categorized blood Pb ranges by age group,<br />

authors calculated relative risk ratios<br />

relating increased blood pressure to<br />

ischemic heart disease, cerebrovascular<br />

disease, hypertensive disease, and other<br />

cardiac diseases. They used a calculation <strong>of</strong><br />

“impact fraction,” based on the proportion<br />

<strong>of</strong> the population within the particular Pb<br />

exposure category and the relative risk at<br />

that exposure category compared to the risk<br />

at the reference level. They used the metaanalysis<br />

<strong>of</strong> Schwartz (1995) to derive an<br />

accumulating 1.25 mm Hg increase in<br />

blood pressure in men <strong>for</strong> 5-10, 10-15, and<br />

15-20 µg/dL, and an increase <strong>of</strong><br />

3.75 mm Hg <strong>for</strong> blood Pb levels above<br />

20 µg/dL. Comparable blood pressure<br />

increases in women <strong>for</strong> each Pb category<br />

was 0.8 mm Hg <strong>for</strong> each <strong>of</strong> the first three<br />

categories and 2.4 mm Hg <strong>for</strong> blood Pb<br />

>20 µg/dL.<br />

See left <strong>for</strong> blood Pb<br />

categories used.<br />

The largest risk ratios were <strong>for</strong> hypertensive disease populations at ages 15-44,<br />

calculated at 1.12, 1.41, 1.78, and 2.00 <strong>for</strong> each <strong>of</strong> the four Pb categories <strong>for</strong><br />

men, and 1.08, 1.25, 1.45, and 1.56 <strong>for</strong> women. Risk ratios <strong>for</strong> all disease<br />

categories increased with increasing Pb category and decreased <strong>for</strong> populations<br />

older than 44 yrs.<br />

The authors assumed a linear relationship between blood pressure and blood<br />

Pb, whereas available evidence suggests it may be non-linear. If blood Pbblood<br />

pressure concentration-response function is log-linear, as implicitly<br />

accepted by over half the reviewed studies, the calculated global risk ratios <strong>for</strong><br />

all cardiovascular disease will be overestimated at higher blood Pb levels and<br />

underestimated at lower blood Pb levels.


AX6-148<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Maheswaran, et al.<br />

(1993)<br />

Europe-England-<br />

Birmingham<br />

1981<br />

Menditto et al.<br />

(1994)<br />

Europe-Rome-<br />

New Risk Factors<br />

Survey<br />

1989-1990<br />

809 out <strong>of</strong> 870 workers, mean (SD)<br />

age 43.3 (10.4) yrs, at an Pb acid<br />

battery plant were used in the study.<br />

Women and workers taking<br />

antihypertensive medications were<br />

excluded. Used multiple linear<br />

regression analyses <strong>of</strong> systolic and<br />

diastolic blood pressure, <strong>for</strong>cing age,<br />

BMI, alcohol use, linear blood Pb, zinc<br />

protoporphyrin, yrs <strong>of</strong> work exposure,<br />

cigarette smoking as covariates.<br />

1319 males, mean (range) age 63 (55-<br />

75) yrs, not treated <strong>for</strong> hypertension,<br />

were used in <strong>for</strong>ward stepwise<br />

multiple linear regression models <strong>of</strong><br />

systolic and diastolic blood pressure<br />

with available covariates <strong>of</strong> age, BMI,<br />

heart rate, serum high density<br />

lipoprotein, non-high density<br />

lipoprotein, triglycerides, glucose,<br />

cigarette use, alcohol use, sum <strong>of</strong> five<br />

skinfold thicknesses (triceps, biceps,<br />

subscapular, suprascapular, and<br />

suprailiac), and natural log<br />

trans<strong>for</strong>med blood Pb.<br />

Geometric mean<br />

(SD) blood Pb:<br />

31.6 µg/dL (5.5)<br />

Median (2.5th-97.5th<br />

percentiles, range)<br />

blood Pb: 11.3 µg/dL<br />

(6.2-24.7, 4-44.2)<br />

Linear blood Pb was not significant <strong>for</strong> either systolic or diastolic blood pressure.<br />

Authors used two indices <strong>of</strong> Pb exposure in the same models. Over much <strong>of</strong> the studied<br />

blood Pb range, zinc protoporphyrin was likely collinear with blood Pb. Linear blood Pb<br />

may not be the appropriate metric to use in blood pressure models. Did not use age-squared<br />

to adjust <strong>for</strong> non-linear relationship <strong>of</strong> blood pressure with age. Did not report model<br />

diagnostics.<br />

Only BMI, heart rate, and serum glucose were not simultaneously and significantly<br />

correlated with both natural log blood Pb and blood pressure. In a systolic blood pressure<br />

model adjusted <strong>for</strong> BMI, age, heart rate, high and non-high density lipoprotein, triglycerides,<br />

glucose, and cigarettes, each unit increase in natural log blood Pb was significantly<br />

associated with a 5.6 mm Hg (95% CI: neither SE nor CI stated) increase in blood pressure.<br />

In a diastolic blood pressure model adjusted <strong>for</strong> BMI, heart rate, age, cigarettes, triglycerides,<br />

and high density lipoprotein, each unit increase in natural log blood Pb was significantly<br />

associated with a 1.7 mm Hg (95% CI: neither SE nor CI stated) increase in blood pressure.<br />

In stratified models <strong>for</strong> alcohol drinkers (n = 1068) and non-drinkers (n = 251) only alcohol<br />

drinkers showed significant natural log blood Pb associated blood pressure increase, with Pb<br />

coefficients similar to those <strong>of</strong> the entire group.<br />

Authors observed change in natural log blood Pb coefficient produced by successive addition<br />

<strong>of</strong> covariates to models. In no case did the coefficients change by more than 30% after<br />

addition <strong>of</strong> a covariate. Authors noted that wine was the predominant drink in alcohol users<br />

and that the correlation between alcohol consumption and natural log blood Pb level was the<br />

highest among all correlations reported (p < 0.001; correlation coefficient not stated).<br />

No statistical tests were made to determine if the change in Pb coefficients with addition <strong>of</strong><br />

covariates was significant, nor were statistical tests made to determine if the Pb coefficients<br />

in the alcohol use stratified models were significantly different. Small size <strong>of</strong> the nonalcohol<br />

drinking group in stratified analysis precludes interpretation <strong>of</strong> non-significant<br />

effects. Incomplete reporting <strong>of</strong> results. Paper published in a supplement issue reporting<br />

meeting papers may indicate that it received less that the normal peer-review scrutiny <strong>for</strong><br />

published research articles. No model diagnostic tests were reported.


AX6-149<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Møller and<br />

Kristensen (1992)<br />

Europe-Denmark-<br />

Copenhagen<br />

County-Glostrup<br />

Population Studies<br />

1976-1990<br />

A cohort born in 1936 was followed at<br />

age 40 (women n = 546, men n = 504),<br />

age 45 (women n = 430, men n = 463) and<br />

again at age 51 (men only n = 439).<br />

Reported no difference in results if<br />

subjects taking antihypertensive<br />

medications were excluded. Reported<br />

results included these subjects. Linear<br />

multiple regression models <strong>of</strong> systolic and<br />

diastolic blood pressure <strong>of</strong> follow up,<br />

stratified by sex and by yr, used a<br />

sequence <strong>of</strong> <strong>for</strong>ced entry <strong>of</strong> covariates:<br />

natural log blood Pb was tested alone<br />

(unadjusted), then adjusted <strong>for</strong> tobacco,<br />

cholesterol, physical activity, and sex<br />

(Model 1), then adjusted <strong>for</strong> the above<br />

covariates plus systolic blood pressure<br />

(Model 2), and then adjusted <strong>for</strong> the above<br />

covariates plus alcohol (Model 3).<br />

Another group <strong>of</strong> linear multiple<br />

regression models <strong>of</strong> change <strong>of</strong> systolic<br />

and diastolic blood pressure from age 40<br />

to 51 yrs in men only, following the same<br />

covariate entry scheme as above, but used<br />

change in covariates instead <strong>of</strong> the<br />

original covariates. All subjects were<br />

followed until 54 yrs <strong>of</strong> age (from 1976 to<br />

1990) to assess Pb association with total<br />

mortality and with coronary heart disease<br />

(CHD; ICD-8 410-414) and<br />

cardiovascular disease (CVD; ICD-8 430-<br />

435) combined morbidity and mortality<br />

using Cox proportional hazards models<br />

(n = 1050). Cox models were adjusted as<br />

above.<br />

Arithmetic mean (SD,<br />

range) blood Pb by age<br />

and sex:<br />

Women 40 yrs:<br />

9.6 µg/dL (3.8, 4-39)<br />

Women 45 yrs:<br />

6.8 µg/dL (3.5, 2-41)<br />

Men 40 yrs: 13.6 µg/dL<br />

(5.7, 5-60)<br />

Men 45 yrs: 9.6 µg/dL<br />

(4.3, 3-39)<br />

Men 51 yrs: 8.3 µg/dL<br />

(4.1, 2-62)<br />

In women, each one unit increase in natural log blood Pb was associated with a<br />

significant increase in systolic blood pressure <strong>of</strong> 4.93 mm Hg (p = 0.002; neither SE nor<br />

CI stated) at age 40 and an increase <strong>of</strong> 2.64 mm Hg (p = 0.06; neither SE nor CI stated)<br />

at age 45, in models adjusted <strong>for</strong> tobacco, BMI, and physical activity (Model 1). When<br />

alcohol (Model 2) or alcohol plus hemoglobin (Model 3) were added to the models Pbblood<br />

pressure relationships were not significant at either age. With each one unit<br />

change in natural log blood Pb, diastolic pressure increased 4.26 mm Hg (p = 0.002;<br />

neither SE nor CI stated) at 40 yrs and 3.26 mm Hg (p = 0.002; neither SE nor CI<br />

stated) at 45 yrs in Model 1. In Model 2, the increase in diastolic blood pressure was<br />

3.21 mm Hg (p = 0.02; neither SE nor CI stated) at 40 yrs and 2.86 mm Hg (p = 0.01;<br />

neither SE nor CI stated) at 45 yrs. In Model 3, the increase in diastolic blood pressure<br />

was 2.65 mm Hg (p = 0.07; neither SE nor CI stated) at 40 yrs and 2.78 mm Hg<br />

(p = 0.01; neither SE nor CI stated) at 45 yrs.<br />

In men, the only significant association between natural log blood Pb and blood<br />

pressure was at 45 yrs. For every increase <strong>of</strong> one unit <strong>of</strong> natural log blood Pb the<br />

increase in systolic blood pressure was 2.73 mm Hg (p = 0.05; neither SE nor CI<br />

stated).<br />

The change in blood Pb between 40 and 51 yrs was not significantly associated with<br />

change in systolic or diastolic blood over the same period in any <strong>of</strong> the models.<br />

None <strong>of</strong> the relative hazard ratios <strong>for</strong> CHD and DVD combined morbidity and mortality<br />

between 40 and 54 yrs were significantly related to blood Pb concentration. Total<br />

mortality, however, was significantly increased with increased blood Pb. In Model 1,<br />

every increase <strong>of</strong> one natural log unit <strong>of</strong> blood Pb was associated with an increased<br />

relative hazard <strong>of</strong> mortality <strong>of</strong> 1.96 (p = 0.009; neither SE nor CI stated). For Model 2,<br />

every increase <strong>of</strong> one natural log unit <strong>of</strong> blood Pb was associated with an increased<br />

relative hazard <strong>of</strong> mortality <strong>of</strong> 1.82 (p = 0.03; neither SE nor CI stated). There were 40<br />

cases <strong>of</strong> CHD recorded, <strong>of</strong> which 13 were fatal. There were 54 cases <strong>of</strong> CVD recorded,<br />

<strong>of</strong> which 19 were fatal. Of the total <strong>of</strong> 46 subjects who died during the period, 32<br />

(70%) died <strong>of</strong> cardiovascular problems. It was not clear if blood Pb at a particular age<br />

or a mean blood Pb across ages was used in the Cox proportional hazards models.


AX6-150<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Møller and<br />

Kristensen (1992)<br />

(cont’d)<br />

Though this study was one <strong>of</strong> the few to use a longitudinal design, it did not<br />

take advantage <strong>of</strong> that design feature in blood pressure modeling. Crosssectional<br />

multiple regression modeling at each age loses valuable in<strong>for</strong>mation<br />

available in repeated measures modeling. Power to detect significant effects is<br />

much higher in repeated measurement modeling than in cross-sectional<br />

modeling. Analyzing only change in blood pressure loses in<strong>for</strong>mation<br />

regarding starting and ending blood pressure. Including change in blood Pb is<br />

problematical due to the unknown history <strong>of</strong> Pb exposure prior to the start <strong>of</strong><br />

the study, the resultant bone Pb load as a result <strong>of</strong> past exposure, the unknown<br />

Pb contribution <strong>of</strong> bone to blood, and the unknown relative contributions <strong>of</strong><br />

past exposure and present exposure to alteration in blood pressure. Modeling<br />

other covariates as change is also questionable. BMI, to pick a covariate with<br />

known and strong effects on blood pressure, may be high and relatively<br />

constant over the study period or low and relatively constant over the study. In<br />

both cases, the change in BMI will be small, but the high BMI will be<br />

associated with higher blood pressure than will the low BMI. Thus, both cases<br />

modeled as change in BMI should have the same effect on blood pressure<br />

when the high BMI subject has expected higher blood pressure than the low<br />

BMI subject. Using difference scores <strong>for</strong> the dependent and the exposure<br />

variables also risks confounding secular trends in either or both <strong>of</strong> these<br />

variables, <strong>for</strong> whatever reasons, with independent difference variable effect on<br />

dependent difference variable effect.<br />

The Cox proportional hazards model, however, is longitudinal in nature.<br />

Failure to detect significant associations between Pb and cardiovascular<br />

morbidity/mortality could have been due to the small sample size used <strong>for</strong> this<br />

type <strong>of</strong> analysis. The blood pressure part <strong>of</strong> the study did not take mortality<br />

into account during the study, which could have produced a progressively<br />

increasing “healthy subject” effect. Since subjects taking antihypertensive<br />

medications were included in analyses, an indicator variable should have been<br />

used to account <strong>for</strong> them, whether or not their exclusion in preliminary testing<br />

produced no apparent change in results. This paper contained a good<br />

discussion <strong>of</strong> confounding variables. Incomplete reporting <strong>of</strong> results and<br />

procedures. No model diagnostic tests were reported.


AX6-151<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Staessen et al.<br />

(1996a)<br />

Europe-Belgium-<br />

PheeCad study.<br />

1985-1995<br />

359 men and 369 women<br />

participated at baseline (between<br />

1985 and 1989) and again about 5<br />

yrs later (median 5.2 yrs) at<br />

follow up (between 1991 and<br />

1995), mean age (range) at<br />

baseline 46 yrs (20-82), about<br />

half <strong>of</strong> whom were recruited from<br />

towns surrounding a non-ferrous<br />

smelter (targeted to produce high<br />

cadmium exposure) and half from<br />

towns without heavy metal<br />

production. Over half the men<br />

had occupational exposure<br />

(59.0% from the near smelter<br />

towns, 17.4% from the other<br />

towns).<br />

Four different outcomes were<br />

explored: time-integrated<br />

conventional blood pressure (avg<br />

<strong>of</strong> 10 baseline and 5 follow up<br />

blood pressure measurements),<br />

24-h ambulatory blood pressure<br />

only during the follow up period<br />

(avg <strong>of</strong> readings every 20 minutes<br />

from 8 AM to 10 PM and every<br />

45 minutes from 10 PM to 8 AM,<br />

weighted by interval between<br />

measurements), difference in<br />

conventional blood pressure over<br />

the five yr follow up period, and<br />

incidence <strong>of</strong> developing<br />

hypertension during follow up.<br />

Geometric mean (5th-<br />

95th percentile) by sex<br />

and time period:<br />

Baseline women:<br />

6.6 µg/dL (3.3-14.5)<br />

Follow up women:<br />

4.8 µg/dL (1.7-11.8)<br />

Baseline men:<br />

11.4 µg/dL<br />

(5.6-28.8)<br />

Follow up men:<br />

7.7 µg/dL<br />

(3.7-20.1)<br />

The study was one <strong>of</strong> the few prospective longitudinal studies reported and was innovative in its<br />

use <strong>of</strong> 24-h ambulatory blood pressure as one <strong>of</strong> its outcome variables.<br />

Time-integrated conventional blood pressure models:<br />

In 187 peri- and post-menopausal women, after adjusting <strong>for</strong> age, BMI, gammaglutamyltransferase<br />

activity, and hematocrit, each increase <strong>of</strong> one unit <strong>of</strong> natural log blood Pb<br />

was associated with an increase in diastolic blood pressure <strong>of</strong> 7.49 mm Hg (95% CI: 1.48,<br />

13.50). No other time-integrated conventional blood pressure measurements were significantly<br />

associated with time-integrated natural log blood Pb in either men or women, nor in stratified<br />

groups within sex.<br />

Ambulatory 24-h blood pressure models:<br />

In all 345 women, after adjusting <strong>for</strong> age, hematocrit, gamma-glutamyltransferase activity, and<br />

oral contraceptive use, each one unit increase in natural log blood Pb was associated with an<br />

increase <strong>of</strong> diastolic blood pressure <strong>of</strong> 3.49 mm Hg (95% CI: 0.02, 6.96). When the group was<br />

limited to the 174 premenopausal women each unit increase in natural log blood Pb was<br />

associated with an increase <strong>of</strong> diastolic blood pressure <strong>of</strong> 5.48 mm Hg (95% CI: 0.56, 10.40).<br />

Difference in blood pressure between baseline and follow up:<br />

After adjustment <strong>for</strong> change in BMI, beginning use <strong>of</strong> antihypertensive medication and<br />

contraceptive medication during the follow up period, and starting smoking there was no<br />

significant relationship between difference in either systolic or diastolic blood pressure and blood<br />

Pb in women. After adjustment <strong>for</strong> change in BMI, change in exposure at work, change in<br />

smoking, beginning use <strong>of</strong> antihypertensive medication in men there was no significant<br />

relationship between difference in either systolic or diastolic blood pressure and blood Pb in<br />

men.<br />

Incidence <strong>of</strong> hypertension:<br />

At baseline 107 (14.7%) and 120 (16.5%) subjects had borderline and definite hypertension,<br />

respectively. At follow up 98 (13.5%) and 186 (25.5%) had borderline and definite<br />

hypertension, respectively. 51 <strong>of</strong> 501 initially normotensive subjects became borderline<br />

hypertensive and 47 <strong>of</strong> the 501 became border line hypertensive during the follow up period.<br />

After adjusting <strong>for</strong> sex, age, and BMI, natural log baseline blood Pb was not related to significant<br />

risk ratios <strong>of</strong> becoming hypertensive (not stated, but presumably combined definite and<br />

borderline hypertension) or becoming a definite hypertensive.


AX6-152<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Staessen et al.<br />

(1996a) (cont’d)<br />

Multiple regression models were used to test the<br />

association between natural log trans<strong>for</strong>med<br />

blood Pb (mean <strong>of</strong> baseline and follow up Pb)<br />

and blood pressure (systolic and diastolic),<br />

stratified by sex, then further stratified by use <strong>of</strong><br />

antihypertensive medications in men and<br />

menopausal status in women. Age and agesquared<br />

(calculated in quintiles) were <strong>for</strong>ced into<br />

the models, then remaining covariates were<br />

stepwise added to the model. Though not<br />

explicitly stated, natural log blood Pb (mean <strong>of</strong><br />

baseline and follow up) was likely <strong>for</strong>ced in last.<br />

Other candidate covariates were BMI,<br />

hemoglobin or hematocrit, serum gammaglutamyltransferase<br />

activity (an index <strong>of</strong> alcohol<br />

use) and serum calcium, 24 h urinary sodium and<br />

potassium excretion, energy expenditure,<br />

exposure to heavy metals (at the workplace),<br />

social class, smoking and drinking habits,<br />

menstrual status in women, and use <strong>of</strong><br />

antihypertensive medications, oral contraceptives,<br />

and hormone replacement therapy. In ambulatory<br />

blood pressure models, differences between<br />

baseline and follow up blood pressure models<br />

were constructed in the same way. For the<br />

difference models “concurrent variations in blood<br />

Pb concentrations” were used, presumably<br />

difference in baseline and blood Pb.<br />

The study does not use the full power <strong>of</strong> repeated measurements in the<br />

analyses. For problems encountered when collapsing repeated<br />

measurements to difference measures, see Møller (1992) above. Stepwise<br />

regressions are prone to capitalizing on chance results due to multiple<br />

testing <strong>of</strong> the same data and almost always produce a different mix <strong>of</strong><br />

covariates when they are stratified. Thus, it was puzzling to find that where<br />

in<strong>for</strong>mation on the effects <strong>of</strong> stepwise covariate addition to models was<br />

available in this article, that the same covariates were listed <strong>for</strong> both models<br />

based on the stratification variable. There is excessive reliance on<br />

fractionation <strong>of</strong> the data set due to multiple stratification, sometimes<br />

reducing the number <strong>of</strong> subjects in a model to as few as 171. Even the<br />

models using the most subjects had only 359 subjects. Low power to detect<br />

significant effects cautions against any interpretation <strong>of</strong> non-significant<br />

results. The time-integrated model used 10 baseline blood pressure<br />

measurements and 5 follow up blood pressure measurements, thus<br />

weighting the avg toward baseline blood pressure. The entry <strong>of</strong> the<br />

biochemical correlate <strong>of</strong> alcohol use in most <strong>of</strong> the models suggests that Pb<br />

effects and Pb-containing alcohol effects on blood pressure were confused,<br />

especially given the European setting and the time period during which the<br />

study was conducted. Control <strong>for</strong> use <strong>of</strong> hypertensive medication rarely<br />

entered models and partial control <strong>for</strong> this variable was achieved only by<br />

stratified analyses, further reducing power to detect significant effects in the<br />

remaining subgroup. No justification was given <strong>for</strong> stratified analyses.<br />

Incomplete in<strong>for</strong>mation in statistical methods and results complicates<br />

interpretation. It was uncertain if stepwise regression was used <strong>for</strong> logistic<br />

models. No comparisons were per<strong>for</strong>med to assess possible bias due to<br />

subject attrition over the course <strong>of</strong> the study.


AX6-153<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Staessen et al.<br />

(1996a) (cont’d)<br />

Staessen et al.<br />

(1993)<br />

Belgium-Cadmibel<br />

Study<br />

1985-1989<br />

For the hypertension incidence model two<br />

definitions <strong>of</strong> hypertension were used:<br />

definite hypertension (systolic >160 mm Hg,<br />

diastolic >95 mm Hg or taking<br />

antihypertensive medications) and borderline<br />

hypertension (systolic between 141 to<br />

159 mm Hg and diastolic between 91 to<br />

94 mm Hg). Method <strong>of</strong> covariate entry into<br />

hypertension incidence models not stated.<br />

Baseline natural log blood Pb was used as the<br />

exposure index.<br />

827 males and 821 females recruited from two<br />

areas in Belgium, one <strong>of</strong> them surrounding a<br />

non-ferrous smelter, mean age (SD) 46 (15)<br />

and 44 (15) yrs, in men and women<br />

respectively. Subjects taking antihypertensive<br />

medication were excluded from the analyses.<br />

Stepwise multiple regression models <strong>of</strong><br />

systolic and diastolic blood pressure were<br />

stratified by sex. Covariates available <strong>for</strong><br />

entry were age and age-squared, BMI, pulse<br />

rate, log protoporphyrin, log gammaglutamyltranspeptidase,<br />

serum calcium, log<br />

serum ferritin, log serum creatinine, log serum<br />

zinc, urinary calcium, urinary sodium, and<br />

urinary potassium. Natural log blood Pb was<br />

the only variable <strong>for</strong>ced into the models.<br />

Additional models tested the interaction <strong>of</strong><br />

serum calcium and blood Pb on blood<br />

pressure.<br />

Geometric mean<br />

blood Pb (range),<br />

stratified by sex:<br />

Male blood Pb:<br />

10.4 µg/dL<br />

(2.7, 84.9)<br />

Female blood Pb:<br />

6.2 µg/dL (1.3, 42.4)<br />

The over six decades <strong>of</strong> age represented in the sample was modeled by linear and<br />

quadratic terms based on age quintiles rather than continuous age, making it likely<br />

that adequate control <strong>for</strong> age effects on blood pressure was not achieved and that<br />

the “healthy subject” effect seen in older groups was not controlled. If stepwise<br />

addition <strong>of</strong> significant covariates was used in the blood pressure difference models,<br />

were covariates in those models that were marked in the coefficient column as<br />

non-significant not included in the models, and if that were so, it is unclear from<br />

where the probability values that substitute <strong>for</strong> the coefficients <strong>of</strong> those variables<br />

were derived. There were no model diagnostic tests reported.<br />

In men, adjusting <strong>for</strong> age and age-squared, BMI, pulse rate, log gammaglutamyltranspeptidase,<br />

serum calcium, and log serum creatinine, every unit<br />

natural log blood Pb increase was significantly associated with a -5.2 mm Hg (95%<br />

CI: !0.5, !9.9) decrease in systolic blood pressure. Natural log blood Pb was not<br />

significant in the model <strong>for</strong> diastolic blood pressure <strong>for</strong> men nor the systolic or<br />

diastolic blood pressure <strong>for</strong> women.<br />

Adjusting <strong>for</strong> age and age-squared, BMI, pulse rate, and log gammaglutamyltranspeptidase,<br />

the interaction term between natural log blood Pb and<br />

serum calcium was only significant <strong>for</strong> systolic blood pressure in women. Every<br />

doubling <strong>of</strong> blood Pb was associated with a 1.0 mm Hg decrease in systolic blood<br />

pressure at serum calcium concentration <strong>of</strong> 2.31 mmol/L (25th percentile) and an<br />

increase in systolic blood pressure <strong>of</strong> 1.5 mm Hg at serum calcium concentration<br />

<strong>of</strong> 2.42 mmol/L (75th percentile).<br />

Stepwise multiple regression analyses run risks <strong>of</strong> accepting chance associations<br />

due to multiple analyses <strong>of</strong> the same data set. The role <strong>of</strong> alcohol use or alcohol<br />

use markers in confounding Pb effect on blood pressure in this setting has already<br />

been noted. The unexplained interaction between serum calcium and blood Pb<br />

highlights the potential confounding role <strong>of</strong> serum calcium with Pb in blood<br />

pressure studies. The study shows graphs indicating distinct differences in the ageserum<br />

calcium and age-blood Pb relationships <strong>for</strong> men and women. From 50-70<br />

yrs <strong>of</strong> age serum calcium is higher than from ≤ 29-49 yrs in women and


AX6-154<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Staessen et al.<br />

(1993) (cont’d)<br />

Telišman et al.<br />

(2004)<br />

Europe-Croatia-<br />

Zagreb<br />

Date <strong>of</strong> data<br />

collection not<br />

given.<br />

100 workers from factories producing Pbbased<br />

products, mean (range) age 30 (20-43)<br />

yrs. Exclusion criteria were absence <strong>of</strong><br />

psychological stress (e.g., death in family)<br />

over last 4 mos, absence <strong>of</strong> verified diabetes,<br />

coronary heart disease, cerebrovascular and<br />

peripheral vascular disease, renal disease,<br />

hyperthyroidism, androgenital syndrome,<br />

primary aldosteronism, and “other diseases<br />

that could influence blood pressure or metal<br />

metabolism.” Linear or natural log blood Pb<br />

were considered <strong>for</strong> stepwise entry in models<br />

<strong>of</strong> systolic and diastolic blood pressure,<br />

<strong>for</strong>cing in all other covariates: blood<br />

cadmium, BMI, age, serum zinc, serum<br />

copper, hematocrit, smoking, and alcohol.<br />

Arithmetic mean<br />

(range) blood Pb:<br />

36.7 µg/dL<br />

(9.9-65.9)<br />

exceeds serum calcium <strong>of</strong> men at those older ages. The steepest rise in<br />

women’s blood Pb with age occurs between the 40-49 and 50-59 yr decades.<br />

The timing <strong>of</strong> these changes in women suggests that menopause may be a<br />

factor, which was accounted <strong>for</strong> only in the model <strong>for</strong> diastolic blood pressure.<br />

It also suggests that serum calcium level and age were also confounded in the<br />

blood pressure models. As serum creatinine clearance and blood Pb are<br />

inversely related, and serum creatinine is a significant covariate in the systolic<br />

blood pressure model <strong>for</strong> men with a significant negative blood Pb coefficient,<br />

it is possible that serum creatinine and blood Pb are confounded with blood<br />

pressure in the men’s systolic blood pressure model. There were no<br />

assessments <strong>of</strong> subject selection bias due to exclusions. The authors note<br />

examining quintile blood pressure relationships with all covariates to determine<br />

the acceptability <strong>of</strong> the linear relationship implied by the linear modeling<br />

technique. No other model diagnostic tests were reported.<br />

Neither linear nor natural log blood Pb entered as significant in multiple<br />

regression models <strong>of</strong> systolic and diastolic blood pressure.<br />

Very small sample size limited power to detect significant effects; nonsignificant<br />

effects should not be interpreted as lack <strong>of</strong> effect. Too many<br />

covariates <strong>for</strong> a small study. Almost no subjects below 10 µg/dL. Taking<br />

hypertensive medications not controlled, likely a problem with top systolic and<br />

diastolic blood pressure in the group 170 mm Hg and 110 mm Hg, respectively.<br />

No model diagnostic testing reported.


AX6-155<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia<br />

Lee et al. (2001)<br />

Korea-Chonan<br />

1997-1999<br />

798 workers from various Pb-using or<br />

producing factories, mean (SD, range) age 40.5<br />

yrs (10.1) [17.8-64.8], 79.4% male, were<br />

classified as to Vitamin D receptor genotype<br />

(VDR bb or Bb/BB) and delta-aminolevulinic<br />

acid dehydratase (ALAD11 or 12) genotype, as<br />

VDR polymorphism has been implicated in<br />

modifications <strong>of</strong> Pb absorption and Pb uptake<br />

and release from bone as well as risk <strong>for</strong><br />

elevated blood pressure and hypertension, and<br />

ALAD polymorphism affects Pb binding to it in<br />

the erythrocyte, the major storage depot <strong>of</strong> Pb in<br />

blood. The hypothesis was that polymorphism<br />

type could influence the effect <strong>of</strong> Pb on blood<br />

pressure and hypertension.<br />

Multiple linear regression models <strong>of</strong> linear<br />

blood Pb, DMSA-chelatable Pb, and tibia Pb<br />

effect on systolic and diastolic blood pressure<br />

with potential covariates <strong>of</strong> age and agesquared,<br />

sex, creatinine clearance, hemoglobin,<br />

weight, height, BMI, job duration, tobacco and<br />

alcohol consumption, pack-yrs <strong>of</strong> tobacco, and<br />

cumulative life time alcoholic drinks. Stepwise<br />

procedure allowed retention <strong>of</strong> covariates only<br />

if they were significant or “there were<br />

substantive changes in the coefficients <strong>of</strong><br />

predictor variables after” their inclusion. In the<br />

models shown, Appearance <strong>of</strong> multiple Pb<br />

variables and the interaction between Pb<br />

variables and genotype <strong>for</strong> each gene depended<br />

upon the specific model. Both ALAD and VDR<br />

receptor polymorphism were sometimes tested<br />

simultaneously in each model containing<br />

polymorphism terms and sometimes VDR<br />

appeared without ALAD.<br />

Arithmetic mean<br />

(SD, range) blood<br />

Pb: 32.0 µg/dL<br />

(15.0, 4-86)<br />

Mean (SD, range)<br />

DMSA-chelatable<br />

Pb: 186 µg<br />

(208.4, 4.8-2103)<br />

Mean (SD, range)<br />

tibia Pb: 37.2 µg/g<br />

(40.4, !7 to 338)<br />

With simple t-tests, subjects with VDR Bb/BB allele were significantly older,<br />

had more DMSA-chelatable Pb, and had higher systolic and diastolic blood<br />

pressure than subjects with VDR bb allele.<br />

In multiple regression models <strong>of</strong> systolic blood pressure, controlling <strong>for</strong> age<br />

and age-squared, sex, BMI, antihypertensive medication use, and cumulative<br />

life-time alcoholic drinks, adding tibia Pb, VDR type, and ALAD type, each<br />

increase <strong>of</strong> 10 µg/g <strong>of</strong> tibia Pb was associated with an increase <strong>of</strong> 0.24 mm Hg<br />

(95% CI: −0.01, 0.49) and VDR BB/Bb type was associated with an increase<br />

<strong>of</strong> 3.24 mm Hg (95% CI: 0.18, 6.30) blood pressure compared to the VDR bb<br />

type. ALAD genotype was not significant. In the same model, but<br />

substituting linear blood Pb <strong>for</strong> tibia Pb, each increase in 1 µg/dL <strong>of</strong> linear<br />

blood Pb was associated with an increase <strong>of</strong> 0.07 mm Hg (95% CI: 0.00,<br />

0.14) and VDR BB/Bb type was associated with an increase <strong>of</strong> 2.86 mm Hg<br />

(95% CI: !0.22, 5.94) blood pressure compared to the VDR bb type. ALAD<br />

genotype had no significant effects on blood pressure.<br />

When both tibia and linear blood Pb were entered simultaneously along with<br />

VDR genotype, adjusting <strong>for</strong> the same covariates, only VDR Bb/BB was<br />

significant; compared to VDR bb, blood pressure was 3.51 mm Hg (95% CI:<br />

2.41, 8.61) higher. ALAD genotype had no significant effects on blood<br />

pressure.<br />

In a model without any Pb terms, VDR genotype was interacted with the age<br />

and the age-squared terms. The VDR Bb/BB genotype interaction with the<br />

linear age term was significant <strong>for</strong> systolic blood pressure. Compared with<br />

the bb genotype the VDR Bb/BB genotypes’ blood pressure increased<br />

0.36 mm Hg (95% CI: 0.06, 0.66) per yr faster with increasing age.<br />

There were no significant effects <strong>of</strong> any Pb variable with diastolic blood<br />

pressure, though the VDR Bb/BB genotype had significantly higher blood<br />

pressure (1.9 mm Hg; not enough in<strong>for</strong>mation given to calculate CI) than the<br />

bb genotypes.<br />

There were no significant interactions <strong>of</strong> the Pb measures with the genotypes<br />

<strong>for</strong> either ALAD or VDR.


AX6-156<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lee et al. (2001)<br />

(cont’d)<br />

Lustberg et al.<br />

(2004)<br />

Korea-Chonan<br />

1997-1999 (period<br />

<strong>of</strong> enrollment; no<br />

statement on dates<br />

<strong>of</strong> data collection)<br />

Logistic regression analysis was used to test<br />

the effect <strong>of</strong> the Pb indices on hypertension<br />

(systolic >160 mm Hg or diastolic<br />

>96 mm Hg or taking antihypertensive<br />

medications) using the same group <strong>of</strong><br />

potential covariates, testing the Pb terms<br />

and the Pb-genotype interaction terms<br />

separately. The hypertension models tested<br />

both gene polymorphisms separately.<br />

793 (number given <strong>for</strong> genotype analysis;<br />

numbers in models not given) current and<br />

<strong>for</strong>mer Pb workers, mean (SD) age 40 (10)<br />

yrs and 80% male, were genotyped <strong>for</strong> the<br />

three polymorphisms <strong>of</strong> endothelial nitric<br />

oxide synthase (eNOS) (GG, GT, TT), an<br />

enzyme that is a modulator <strong>of</strong> vascular<br />

resistance. The effect <strong>of</strong> genotype and the<br />

interaction <strong>of</strong> genotype with blood Pb and<br />

tibia Pb on systolic and diastolic blood<br />

pressure were evaluated by multiple linear<br />

regression analyses, <strong>for</strong>cing covariates <strong>of</strong><br />

age (modeled as a 2 degree <strong>of</strong> freedom<br />

spline with knot at 45 yrs), sex, natural log<br />

BMI, smoking and alcohol consumption,<br />

high school education, and job duration.<br />

Both blood Pb and tibia Pb were entered as<br />

percentiles and entered together. Logistic<br />

models <strong>of</strong> hypertension (systolic<br />

∃140 mm Hg or diastolic ∃90 mm Hg or<br />

reported use <strong>of</strong> antihypertensive<br />

medication) used the same covariates.<br />

Interaction terms between each <strong>of</strong> the Pb<br />

measures (plus a Pb-squared term) and<br />

genotype was used to determine differential<br />

effect <strong>of</strong> Pb according to genotype.<br />

Pb according to<br />

genotype:<br />

Arithmetic mean<br />

(SD) blood Pb, GG:<br />

32 (15) µg/dL<br />

Arithmetic mean<br />

(SD) blood Pb,<br />

TG/TT: 32<br />

(15) µg/dL<br />

Mean (SD) tibia Pb,<br />

GG: 37 (42) µg/g<br />

Mean (SD) tibia Pb,<br />

TC/TT: 36 (34) µg/g<br />

Subjects with the Bb/BB genotypes had a significantly higher odds hypertension<br />

prevalence (OR = 2.1 [95% CI: 1.0, 4.4]) than subjects with the bb genotype,<br />

adjusting <strong>for</strong> age, sex, BMI, tibia Pb, and current alcohol use. There were no<br />

significant effects <strong>of</strong> any Pb variable nor <strong>of</strong> ALAD on hypertension status.<br />

Linear blood Pb may not give efficient and unbiased estimates <strong>of</strong> blood Pb effect on<br />

blood pressure. The descriptive data shows highly skewed distributions <strong>for</strong> blood Pb,<br />

DMSA-chelatable Pb, and tibia Pb in this group, suggesting that coefficients <strong>of</strong> all Pb<br />

effect on blood pressure may not have been efficient and unbiased. Stepwise models<br />

usually produce different covariate patterns <strong>for</strong> different models, though the tables<br />

indicate that the covariates used <strong>for</strong> all the models discussed above were the same. No<br />

model diagnostic tests were reported.<br />

85% (673/793) <strong>of</strong> the group were typed GG, 14% (114/793) were TG, and 1% (6/793)<br />

were TT. TG and TT groups were combined <strong>for</strong> analysis (TG/TT).<br />

Mean systolic and diastolic blood pressures, adjusted <strong>for</strong> all covariates, were not<br />

significantly different between GG and TG/TT groups.<br />

In multiple regression models <strong>for</strong> systolic and diastolic blood pressure, neither<br />

percentile blood Pb nor percentile tibia Pb, entered together, were significant<br />

predictors. Interaction terms between the Pb variables and genotype were not<br />

significant.<br />

In the logistic regression model <strong>for</strong> hypertension, neither percentile blood Pb nor<br />

percentile tibia Pb, entered together, were significant predictors.<br />

Reporting was incomplete: number <strong>of</strong> subjects entering the models was not stated; no<br />

comparisons between recruited subjects and subjects not used in models. Despite<br />

reporting non-significant interactions, the paper showed both loess plots and tables <strong>of</strong><br />

analyses stratified by genotype, reporting significant associations between both tibia<br />

and blood Pb in the GG genotype, insignificant in the other. Inspection <strong>of</strong> the loess<br />

plots revealed striking non-linearity <strong>for</strong> both adjusted blood Pb-systolic blood pressure<br />

and adjusted tibia Pb-systolic blood pressure relationships. Small group size <strong>of</strong> the<br />

TG/TT genotypes and highly unbalanced terms <strong>of</strong> the interaction may have<br />

contributed to the non-significant interactions. Although the interaction Pb term was<br />

also probed as a quadratic function, the tibia Pb interaction was not, suggesting that<br />

poor concentration-response specification in the model may also have contributed to<br />

the lack <strong>of</strong> significant main effects and interactions.


AX6-157<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Nomiyama et al.<br />

(2002)<br />

China, Beijing<br />

No statement on<br />

dates <strong>of</strong> data<br />

collection<br />

123 female Pb-exposed leaded crystal toy<br />

workers, mean age (range) 27.3 (17-44) yrs,<br />

and 70 female sewing workers (reference<br />

group), mean age (range) 24.2 (16-58) yrs<br />

were tested. Forward stepwise multiple<br />

regression models <strong>of</strong> systolic and diastolic<br />

blood pressure <strong>of</strong> the combined groups<br />

were used with linear blood Pb and a set <strong>of</strong><br />

covariates. Variables with p < 0.2 were<br />

allowed to enter. The covariate set was<br />

selected from a larger set <strong>of</strong> potential<br />

covariates by factor analysis, and a<br />

representative variable from each factor<br />

was selected <strong>for</strong> possible entry in the<br />

regressions.<br />

Alternate models were constructed using<br />

four ordered categories <strong>of</strong> blood Pb, instead<br />

<strong>of</strong> the linear continuous blood Pb variable.<br />

Logistic regressions were used to determine<br />

the odds <strong>of</strong> elevated systolic (∃125 mm Hg)<br />

and elevated diastolic (∃80 mm Hg) blood<br />

pressure as a function <strong>of</strong> blood Pb category.<br />

Blood Pb mean<br />

(SD, range) in Pb<br />

workers: 55.4<br />

(13.5, 22.5-<br />

99.4 µg/dL<br />

Blood Pb mean<br />

(SD, range) in non-<br />

Pb workers:<br />

6.4 (1.6, 3.8-<br />

11.4) µg/dL<br />

Adjusted <strong>for</strong> age, urine protein, and plasma triglyceride, each 1 µg/dL increase in<br />

linear blood Pb significantly associated with a 0.13 mm Hg increase in systolic<br />

blood pressure (no SE or CI given; p = 0.0003). Adjusted <strong>for</strong> plasma triglyceride,<br />

age, urine protein, plasma low density lipoprotein, and hypertension heredity, each<br />

1 µg/dL increase in linear blood Pb was associated with a 0.10 mm Hg increase in<br />

diastolic blood pressure (no SE or CI given; p = 0.0001).<br />

Using the ordered categories <strong>of</strong> blood Pb and the same covariates <strong>for</strong> systolic and<br />

diastolic blood pressure, the 40-60 µg/dL group had 4.2 mm Hg (95% CI: 0.0, 8.5)<br />

higher systolic blood pressure and 4.1 mm Hg (95% CI: 1.3, 6.8) higher diastolic<br />

blood pressure than the reference group (blood Pb (


AX6-158<br />

Table AX6-5.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Blood Pressure and Hypertension<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Wu et al. (1996)<br />

Central Taiwan<br />

No statement on<br />

dates <strong>of</strong> data<br />

collection<br />

222 workers in two Pb battery plants, 112<br />

men, mean (range) age 36.2 (18-67) yrs, and<br />

110 women, mean (range) age 36.2 (18-71)<br />

yrs were tested <strong>for</strong> blood Pb relationships<br />

with systolic and diastolic blood pressure in<br />

multiple regression models, using a fixed,<br />

<strong>for</strong>ced set <strong>of</strong> covariates: age, sex, BMI,<br />

working history, yrs <strong>of</strong> work, noise exposure,<br />

natural log ambient air Pb concentration, and<br />

ordered categorical blood Pb concentration.<br />

Arithmetic mean (SD,<br />

range) blood Pb:<br />

Women: 44.6 (18.4,<br />

8.3-103.1) µg/dL<br />

Men: 60.2 (26.8,<br />

17.0-150.4) µg/dL<br />

Using four ordered blood Pb categories (60 µg/dL<br />

[85/222; 38.3%]) adjusted systolic and diastolic blood pressure were not<br />

significantly related to the top three blood Pb categories compared to the<br />

lowest, natural log ambient Pb. Yrs in work environment was a significant<br />

predictor <strong>of</strong> both systolic and diastolic blood pressure, but age was only<br />

marginally significant <strong>for</strong> systolic blood pressure and not significant <strong>for</strong><br />

diastolic blood pressure.<br />

Small study size limits any conclusions drawn from non-significant results.<br />

Three measures, all related to Pb exposure, were simultaneously tested in the<br />

models. While blood Pb may only be weakly correlated with yrs <strong>of</strong> work,<br />

ambient air Pb would be expected to be much better correlated with blood Pb.<br />

There is a clear possibility <strong>of</strong> collinearity among those three variables, which<br />

would inflate standard errors and reduce coefficients. Authors selected<br />

ordered categories <strong>of</strong> Pb to “avoid unnecessary assumption <strong>of</strong> linearity.” The<br />

use <strong>of</strong> natural log air Pb concentration suggests that some diagnostics were<br />

run, but no model diagnostic tests were reported. No control <strong>for</strong><br />

antihypertensive medication use.


AX6-159<br />

Table AX6-5.2. Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Morbidity<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Cheng et al.<br />

(1998)<br />

U.S.-Boston,<br />

Normative Aging<br />

Study (VA)<br />

1991-1995<br />

Gump et al. (2005)<br />

U.S.-Oswego, NY<br />

Dates <strong>of</strong> study not<br />

given<br />

775 males (97% white), mean age (SD,<br />

range) 67.8 yrs (7.3, 48-93).<br />

Multiple linear regression models <strong>of</strong><br />

heart rate-corrected QT and QRS<br />

electrocardiogram intervals were<br />

adjusted by stepwise entry <strong>of</strong><br />

covariates, retaining only those that<br />

remained significant at p < 0.10.<br />

Linear blood Pb, tibia, and patella bone<br />

Pb were apparently (not described in<br />

text) entered separately. Logistic<br />

regression models <strong>for</strong> Minnesota ECG<br />

Coding Center diagnoses <strong>of</strong><br />

intraventricular conduction deficit<br />

(IVCD), atrioventricular conduction<br />

deficit (AVCD), and arrhythmia were<br />

adjusted by covariates the same way.<br />

Only analyses stratified by age (


AX6-160<br />

Table AX6-5.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Morbidity<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Navas-Acien<br />

(2004)<br />

U.S.-NHANES<br />

IV-Phase 1<br />

1999-2000<br />

Schwartz (1991)<br />

NHANES <strong>II</strong><br />

U.S.<br />

1976-1980<br />

2125 subjects (1070 males, 1055<br />

females), age 40->70 yrs were tested<br />

<strong>for</strong> peripheral arterial disease (PAD;<br />

n = 139) by taking the ratio <strong>of</strong> the<br />

ankle mean systolic blood pressure to<br />

the arm mean systolic blood pressure.<br />

Any subject with the ratio


AX6-161<br />

Table AX6-5.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Morbidity<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Tepper et al.<br />

(2001)<br />

U.S.-Cincinnati,<br />

OH<br />

After 1991 to<br />

be<strong>for</strong>e 2001<br />

Europe<br />

Gustavsson et al.<br />

(2001)<br />

Europe-<br />

Stockholm,<br />

Sweden<br />

1992-1994<br />

See Tepper et al. (2001) entry in Blood<br />

Pressure and Hypertension <strong>for</strong> left<br />

ventricular mass results.<br />

Study base was all Swedish citizens<br />

45-70 yrs old from Stockholm County<br />

free <strong>of</strong> previous myocardial infarction.<br />

Cases who survived at least 28 days<br />

after infarct (1,105 males and 538<br />

females) <strong>of</strong> which 937 men (85%) and<br />

398 women (74%) had sufficient<br />

in<strong>for</strong>mation on occupational exposures<br />

and “main confounders”, were<br />

compared against referents (1,120 men<br />

and 538 women) matched to cases by<br />

sex, age, yr, and hospital catchment<br />

area. Risk ratios <strong>for</strong> the case group<br />

compared to referent group were<br />

adjusted on the basis <strong>of</strong> the matching<br />

variables and smoking, alcohol<br />

drinking, hypertension, overweight,<br />

diabetes mellitus, leisure physical<br />

“inactivity”, and were calculated <strong>for</strong> a<br />

number <strong>of</strong> exposure factors separately,<br />

including Pb.<br />

Pb exposure was<br />

classified as none, low or<br />

high corresponding to<br />

airborne dust levels <strong>of</strong> 0,<br />

>0 to 0.03, and<br />

∃0.04 mg/m 3 ,<br />

respectively, <strong>for</strong> the<br />

highest intensity <strong>of</strong><br />

exposure during at least<br />

one yr <strong>of</strong> work. The same<br />

three classifications were<br />

used <strong>for</strong> 0, >0 to 0.04, and<br />

∃0.05 mg/m 3 <strong>for</strong><br />

cumulative exposure.<br />

All risk ratios were calculated relative to the “no exposure” groups. Adjusted<br />

risk ratios <strong>for</strong> surviving a myocardial infarction were 0.88 (95% CI: 0.69, 1.12)<br />

and 1.03 (95% CI: 0.64, 1.65) <strong>for</strong> low and high exposure groups <strong>for</strong> peak Pb<br />

exposure, and were 0.81 (95% CI: 0.60, 1.11) and 1.00 (0.74, 1.34) <strong>for</strong> the low<br />

and high cumulative exposure groups.<br />

This study <strong>of</strong> myocardial morbidity was compromised by poor Pb exposure<br />

characterization (occupational air dust Pb concentration) and by including a<br />

covariate collinear with Pb exposure and confounded with the outcome,<br />

hypertension, in the adjusted models.<br />

No model diagnostics were reported.


AX6-162<br />

Table AX6-5.3. Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Mortality<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Lustberg and<br />

Silbergeld (2002)<br />

U.S.-NHANES <strong>II</strong><br />

1976-1980,<br />

follow up to 1992<br />

Schober et al.<br />

(2006)<br />

U.S.-NHANES<br />

<strong>II</strong>I<br />

1988-1994,<br />

follow up to 2000<br />

4190 persons, 30 to 74 yrs, 929 <strong>of</strong> whom<br />

died during follow up, had baseline blood Pb<br />

measurements during the NHANES <strong>II</strong><br />

period. Proportional hazard models <strong>for</strong><br />

circulatory disease-related death (ICD-9<br />

codes 390-459) were based on the complex<br />

survey design, but not weighted. Presented<br />

models were unadjusted, adjusted <strong>for</strong> age<br />

and sex, and adjusted <strong>for</strong> age, sex, location,<br />

education, race, income, smoking, BMI, and<br />

exercise. Blood Pb was entered as an<br />

ordinal three-category variable.<br />

9757 persons, age 40 yrs, 2515 <strong>of</strong> whom<br />

died during follow-up (median length <strong>of</strong><br />

follow-up 8.55 yrs), had baseline blood Pb<br />

measurements during the NHANES <strong>II</strong>I<br />

period. Analyses were per<strong>for</strong>med using<br />

proportional hazard models <strong>for</strong> all cause<br />

deaths, major cardiovascular disease-related<br />

deaths (I00-I78), and malignant neoplasms<br />

(C00-C97). Multivariate models were<br />

adjusted <strong>for</strong> sex, race/ethnicity, education,<br />

and smoking status and stratified by age.<br />

Blood Pb was entered as an ordinal threecategory<br />

variable.<br />

Blood Pb


AX6-163<br />

Table AX6-5.3 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Mortality<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Michaels et al.<br />

(1991)<br />

U.S.-New York<br />

City<br />

1961-1984<br />

1261 males, avg age (range) at the<br />

beginning <strong>of</strong> study 49.6 yrs (19-83),<br />

representing 24,473 person-yrs were<br />

followed. 498 died in the interval.<br />

Subjects belonged to the International<br />

Typographical Union and worked at two<br />

large city newspapers. Hot Pb linotyping<br />

was discontinued at the newspapers<br />

during 1974-1978, providing the primary<br />

source <strong>of</strong> occupational exposure. Last<br />

exposure <strong>for</strong> all subjects still employed<br />

was at the end <strong>of</strong> 1976.<br />

Standardized mortality ratios (SMR)<br />

were calculated using the LTAS program<br />

developed by NIOSH, calculating the<br />

expected number <strong>of</strong> deaths <strong>of</strong> the cohort<br />

referenced to a comparison population, in<br />

this case disease-specific mortality rates<br />

from New York City. Cohort was<br />

stratified based on yrs <strong>of</strong> employment.<br />

Causes <strong>of</strong> death were based on ICD-8<br />

codes.<br />

Exposure was estimated<br />

based on yrs <strong>of</strong> linotype<br />

employment be<strong>for</strong>e the<br />

end <strong>of</strong> 1976. Authors<br />

note that, based on<br />

measurements at other<br />

print shops using hot Pb<br />

linotype, air Pb levels<br />

probably did not exceed<br />

20 µg/m 3 .<br />

Standardized mortality ratio was significant (SMR = 1.68 [95% CI: 1.18, 2.31])<br />

only <strong>for</strong> cerebrovascular disease in those working, and thus exposed, <strong>for</strong> 30 yrs<br />

or more. Neither arteriosclerotic heart disease (ICD-8 410-414) nor vascular<br />

lesions <strong>of</strong> the central nervous system (ICD-8 430-438) had significant SMR in<br />

the total cohort not stratified by yrs <strong>of</strong> exposure.<br />

No direct measurement <strong>of</strong> Pb exposure. Many groupings <strong>of</strong> ICD codes were<br />

explored in stratified and unstratified analyses, with the only significantly<br />

elevated SMR found <strong>for</strong> cerebrovascular disease. No a priori hypotheses.<br />

General weakness <strong>of</strong> all studies relying on a comparison population is that the<br />

cohort belongs to the comparison population and can influence the comparison<br />

mortality rates in direct proportion to the ratio between cohort and comparison<br />

population size.


AX6-164<br />

Table AX6-5.3 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Mortality<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Steenland et al.<br />

(1992)<br />

U.S.-Idaho<br />

>1941 to 1988<br />

The death certificates <strong>of</strong> 1028 males <strong>of</strong><br />

the 1990 who worked at a smelter plant<br />

at least one yr between 1940 and 1965<br />

were examined to construct standardized<br />

mortality ratios (SMR) <strong>for</strong> various ICD-9<br />

disease classifications using the U.S.<br />

population as a referent group.<br />

In 1976 blood Pb <strong>of</strong><br />

173 workers avgd (SD)<br />

56.3 µg/dL (12.9). <strong>Air</strong><br />

Pb was measured in<br />

1975 at 3.1 mg/m 3 in<br />

208 personal 8-h<br />

samples. High Pb<br />

departments in the plant<br />

were defined as those<br />

exceeding 0.2 mg/m 3 in<br />

the 1975 survey.<br />

Non-malignant respiratory disease and accidents accounted <strong>for</strong> most <strong>of</strong> the<br />

significantly elevated SMR in the group. SMRs were not significantly elevated<br />

<strong>for</strong> ischemic heart disease (410-414), SMR = 0.94 (95% CI: 0.84, 1.05);<br />

hypertension with heart disease (402, 404), SMR = 0.97 (95% CI: 0.53, 1.63);<br />

hypertension with no heart disease (401, 403, 405), SMR = 1.73 (95% CI: 0.63,<br />

3.77); or cerebrovascular diseases (430-436), SMR = 1.05 (95% CI: 0.82, 1.32).<br />

Similar results were found <strong>for</strong> the people working in the “high Pb departments.”<br />

Though there is no doubt that this group was highly exposed to Pb, exposure<br />

characterization over the working lifetime was not well defined, few blood Pb<br />

data were available, and poor demographic data <strong>for</strong> the exposed group only<br />

allowed a comparison with total U.S. population. As is usual with occupationally<br />

exposed groups, selection bias may influence results. No smoking data were<br />

available <strong>for</strong> the group. In industrial conditions smoking will be confounded<br />

with other Pb exposure (constant hand to mouth behavior on the plant floor will<br />

exposure smokers to more Pb via the oral route than in non-smokers).


AX6-165<br />

Table AX6-5.3 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Cardiovascular Mortality<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Gerhardsson et al.<br />

(1995)<br />

Europe-southern<br />

Sweden<br />

1969-1989<br />

Møller and<br />

Kristensen (1992)<br />

Europe-Denmark-<br />

Copenhagen<br />

County-Glostrup<br />

Population Studies<br />

1976-1990<br />

664 male workers at a secondary Pb<br />

smelter had blood Pb tested every 2-3<br />

mos since 1969. The past blood Pb level<br />

<strong>of</strong> 201 workers who had been working at<br />

the plant from be<strong>for</strong>e 1969 was estimated<br />

from their 1969 results. Median (10th<br />

percentile, 90th percentile) yr <strong>of</strong> birth<br />

was 1943 (1918, 1960). Median (10th<br />

percentile, 90th percentile) duration <strong>of</strong><br />

employment was 2.8 yrs (0.3, 25.7) and<br />

median (10th percentile, 90th percentile)<br />

duration <strong>of</strong> follow up was 13.8 yrs (2.8,<br />

20.9). A total <strong>of</strong> 8706 person-yrs were<br />

represented in the study. Standardized<br />

mortality ratios based on county<br />

mortality tables by calendar yr, cause,<br />

sex and five-yr age group were<br />

calculated. Cardiovascular diseases were<br />

coded by ICD-8 from death certificates.<br />

See Møller et al. (1992) entry in Blood<br />

Pressure and Hypertension <strong>for</strong> results <strong>of</strong><br />

cardiovascular disease and coronary heart<br />

disease mortality.<br />

Arithmetic mean blood<br />

Pb levels dropped from<br />

~62 µg/dL in 1969 to<br />

~33 µg/dL in 1985.<br />

95% CI were difficult<br />

to extract from the<br />

presented graph, but<br />

appeared to be no more<br />

than 5-6 µg/dL about<br />

the mean.<br />

All cardiovascular disease mortality (ICD-8 390-458) was significantly elevated<br />

above that expected from the county mortality tables (SMR = 1.46 [95% CI:<br />

1.05, 2.02]), with 39 <strong>of</strong> the 85 deaths observed in the cohort. For just ischemic<br />

heart disease (ICD-8 410-414), SMR = 1.72 (95% CI: 1.20, 2.42) in the plant<br />

workers with 34 <strong>of</strong> the 85 deaths observed in the cohort. There were no deaths<br />

recorded <strong>for</strong> cerebrovascular diseases (ICD-9 430-438). There was no apparent<br />

concentration-response relationship, using peak blood Pb and time-integrated<br />

blood Pb.<br />

Problems inherent in using standardized mortality ratios in such mortality studies<br />

have been discussed above. The sample size was too small (85 all cause deaths<br />

among 664 workers) to interpret non-significant results.


AX6-166<br />

Table AX6-5.4. Cardiovascular Effects <strong>of</strong> <strong>Lead</strong> on Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Chen et al. (2006)<br />

U.S.-Baltimore, MD;<br />

Cincinnati, OH;<br />

Newark, NJ;<br />

Philadelphia, PA<br />

~1998-2004<br />

780 children from 12-33 mos participated<br />

in a randomized clinical trial <strong>of</strong> oral<br />

succimer chelation in four clinical<br />

centers. Half the children had up to three<br />

26-day treatments, the other half were<br />

given placebo. 75% got two treatment<br />

sessions and 81% <strong>of</strong> those with two<br />

treatments received a third.<br />

Blood pressure was measured pretreatment,<br />

at 7, 28, and 42 days after each<br />

treatment, then every 3 to 4 mos <strong>for</strong> five<br />

yrs <strong>of</strong> follow up. Cross-sectional<br />

multiple regression models adjusting <strong>for</strong><br />

clinic location, baseline linear Pb, race,<br />

sex, parents’ education, single parent, age<br />

at test, height at test, and BMI at test <strong>for</strong><br />

each period <strong>of</strong> the study tested the<br />

difference <strong>of</strong> diastolic and systolic blood<br />

pressure between placebo and succimer<br />

groups. Cross-sectional multiple<br />

regression models <strong>for</strong> the effect <strong>of</strong> linear<br />

blood Pb at each period on blood<br />

pressure adjusted <strong>for</strong> clinic location,<br />

treatment group, race, sex, parents’<br />

education, single parent, age at test,<br />

height and BMI. Two mixed models,<br />

one from start <strong>of</strong> treatment to 9-mo<br />

follow up, the other from 12 to 60 mos<br />

follow up, adjusted <strong>for</strong> the same<br />

variables, and tested the effect <strong>of</strong><br />

treatment group over time.<br />

Blood Pb ranged from<br />

20-44 µg/dL at pre-treatment<br />

and from 1-27 µg/dL at 5 yr<br />

follow up. Succimer-treated<br />

group had significantly<br />

lower blood Pb than placebo<br />

group only <strong>for</strong> 9-10 mos<br />

following the end <strong>of</strong><br />

treatment. Blood Pb did not<br />

differ significantly beyond<br />

that period.<br />

Adjusted systolic blood pressure was significantly higher in the succimer<br />

group than the placebo group at 36 mos (1.27 mm Hg [95% CI: 0.06,<br />

2.48]) and at 60 mos follow up (1.69 mm Hg [95% CI: 0.34, 3.04]).<br />

Systolic blood pressure was not significantly different at any other time<br />

period; diastolic blood pressure was never significantly different between<br />

groups.<br />

Concurrent linear blood Pb was not associated with blood pressure in<br />

cross-sectional models at any time point in the study. Adjusted<br />

coefficients <strong>for</strong> linear blood Pb and systolic blood pressure ranged from<br />

1.36 mm Hg (95% CI: !0.58, 3.30) at pre-treatment to !0.72 mm Hg (95%<br />

CI: !1.91, 0.48) at 36 mos <strong>of</strong> follow up. Diastolic pressure coefficients<br />

were generally lower but followed the same pattern.<br />

Mixed model analysis <strong>for</strong> start <strong>of</strong> treatment through 9 mos follow up<br />

showed succimer treatment effect <strong>of</strong> 0.24 mm Hg (95% CI: !0.79, 1.28)<br />

<strong>for</strong> systolic and 0.46 mm Hg (95% CI: !0.44, 1.36) <strong>for</strong> diastolic blood<br />

pressure. The treatment effect from 12 through 60 mos follow up was<br />

1.09 mm Hg (95% CI: 0.27, 1.90) systolic and 0.15 mm Hg (95% CI:<br />

!0.45, 0.75) <strong>for</strong> diastolic blood pressure.<br />

The only reliable effect <strong>of</strong> succimer treatment was an elevation <strong>of</strong> systolic<br />

blood pressure, especially notable between three and five yrs post<br />

treatment. The authors could not account <strong>for</strong> the apparent increase in<br />

blood pressure in the succimer-treated group 3-5 yrs after treatment ended.<br />

It is notable that the two groups had different mean blood Pb <strong>for</strong> less than<br />

a yr after succimer treatment ended, a period perhaps too short to observe<br />

any beneficial effect <strong>of</strong> treatment. Failure to find cross-sectional effects <strong>of</strong><br />

blood Pb on blood pressure, especially pre-treatment, may indicate that Pb<br />

exposure <strong>for</strong> a period <strong>of</strong> less than three yrs after birth is not sufficient to<br />

affect blood pressure or that blood pressure measurements in the first three<br />

yrs <strong>of</strong> life are highly variable, as could be seen from scatter plots <strong>of</strong> blood<br />

pressure vs. blood Pb at pre-treatment compared 60 mo follow up. The<br />

use <strong>of</strong> linear Pb term may have reduced sensitivity to finding a significant<br />

blood Pb effect on blood pressure. No model diagnostics mentioned.


AX6-167<br />

Table AX6-5.4 (cont’d). Cardiovascular Effects <strong>of</strong> <strong>Lead</strong> on Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Gump et al. (2005)<br />

U.S.-Oswego, NY<br />

Dates <strong>of</strong> study not<br />

given<br />

Europe<br />

Factor-Litvak et al.<br />

(1996)<br />

Europe-Kosovska<br />

Mitrovica and Pristina,<br />

Kosovo<br />

~1992-1993<br />

122 9.5-yr old children participated.<br />

Multiple regression models <strong>of</strong> percent<br />

changes in systolic and diastolic blood<br />

pressure, heart rate, stroke volume,<br />

cardiac output, and total peripheral<br />

resistance due to acute stress were<br />

adjusted by stepwise entry <strong>of</strong> up to<br />

50 possible control variables with<br />

quartile blood Pb <strong>for</strong>ced in last. A linear<br />

contrast was used to test dose-response<br />

effects <strong>of</strong> quartile Pb. Linear Pb terms<br />

were also used.<br />

281 5.5-yr old children studied since<br />

pregnancy participated. Multiple linear<br />

regression models <strong>of</strong> systolic blood<br />

pressure, adjusted <strong>for</strong> height, BMI,<br />

gender, ethnic group, and birth order, and<br />

diastolic blood pressure, adjusted <strong>for</strong><br />

waist circumference, ethnic group, and<br />

birth order were constructed by stepwise<br />

elimination from a larger pool <strong>of</strong><br />

potential confounding variables and<br />

retained if they modified the linear blood<br />

Pb coefficient by more the 10%.<br />

Contemporary blood Pb<br />

quartile:<br />

1st quartile: 1.5-2.8 µg/dL<br />

2nd quartile: 2.9-4.1 µg/dL<br />

3rd quartile: 4.2-5.4 µg/dL<br />

4th quartile: 5.5-13.1 µg/dL<br />

Blood Pb arithmetic mean<br />

(range):<br />

22.7 µg/dL (5-55)<br />

All ∃ represent percent change in outcome from nonstress to stress<br />

condition <strong>for</strong> each change in 1 µg/dL blood Pb.<br />

Systolic blood pressure: ∃ = !0.009 (95% CI: !0.74, 0.055)<br />

Diastolic blood pressure: ∃ = 0.069 (95% CI: !0.001, 0.138)<br />

Heart rate: ∃ = 0.013 (95% CI: !0.046, 0.072)<br />

Stroke volume: ∃ = !0.069 (95% CI: !0.124, !0.015)<br />

Cardiac output: ∃ = !0.056 (95% CI: !0.113, 0.001)<br />

Total peripheral resistance: ∃ = 0.088 (95% CI: 0.024, 0.152)<br />

Mean successive difference <strong>of</strong> cardiac interbeat interval:<br />

∃ = !0.028 (95% CI: (!0.098, 0.042)<br />

Despite low power to detect significant effects, blood pressure, cardiac<br />

output, and total peripheral resistance change to stress were associated<br />

with contemporary blood Pb. Stepwise modeling creates unique<br />

models <strong>for</strong> each outcome. Some models had up to 12 control variables<br />

plus Pb, an excessive number <strong>for</strong> only 122 subjects. Scatter plots <strong>of</strong><br />

regression with linear Pb and bar charts <strong>of</strong> response to quartile Pb<br />

showed obvious non-linearity, though all Pb effects were modeled as<br />

linear effects. Probability <strong>of</strong> contemporary exposure to mercury and<br />

PCB’s was very high. No model diagnostic testing reported.<br />

For each increase <strong>of</strong> 1 µg/dL <strong>of</strong> blood Pb:<br />

Systolic blood pressure: ∃ = 0.054 (95% CI: !0.024, 0.13)<br />

Diastolic blood pressure: ∃ = 0.042 (95% CI: !0.01, 0.090)<br />

Despite low power to detect significant effects, there was a marginally<br />

significant tendency <strong>for</strong> blood pressure to be positively associated with<br />

blood Pb. Stepwise multiple regression may have capitalized on<br />

chance results. The linear Pb term may have reduced the ability to<br />

detect significant effects <strong>of</strong> Pb if the modeled relationship were<br />

nonlinear. Log Pb was tested but not reported. A quadratic Pb term<br />

was reported nonsignificant. No model diagnostics reported.


ANNEX TABLES AX6-6<br />

AX6-168


AX6-169<br />

Table AX6-6.1. Placental Transfer <strong>of</strong> <strong>Lead</strong> from Mother to Fetus<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Harville et al. (2005)<br />

Pittsburgh, PA<br />

Angell and Lavery<br />

(1982)<br />

Louisville, KY<br />

Bogden et al. (1978)<br />

Newark, NJ<br />

159 mother-infant pairs. Maternal blood Pb at delivery:<br />

Mean 1.93 µg/dL (range 0.55-4.70)<br />

635 cord blood specimens. 154 maternal<br />

and infant blood samples collected 24 h<br />

postpartum from these deliveries.<br />

25 deliveries <strong>of</strong> infants with birth weights<br />

between 1,500-2,500g and 50 matched<br />

controls with birth weights above 2,500g.<br />

Cord blood Pb:<br />

Mean 1.64 µg/dL (range 0.05-3.95)<br />

Maternal blood Pb:<br />

Mean 9.85 µg/dL (SD 4.4)<br />

Infant blood Pb:<br />

Mean 9.82 µg/dL (SD 4.8)<br />

Cord blood Pb:<br />

Mean 9.78 µg/dL (SD 4.1)<br />

Low birth weight infants:<br />

Maternal blood Pb:<br />

Mean 16.2 µg/dL (SD 4.5)<br />

Cord blood Pb:<br />

Mean 13.8 µg/dL (SD 4.4)<br />

Normal birth weight infants:<br />

Maternal blood Pb:<br />

Mean 15.3 µg/dL (SD 5.2)<br />

Cord blood Pb:<br />

Mean 13.1 µg/dL (SD 4.3)<br />

Correlation coefficient = 0.79<br />

On avg, cord blood Pb was lower than maternal<br />

blood Pb by 0.03 µg/dL (95% CI: 0.21, 0.38).<br />

Maternal-infant blood Pb:<br />

Correlation coefficient = 0.73, ∃ = 0.73<br />

Maternal-cord blood Pb:<br />

Correlation coefficient = 0.60, ∃ = 0.55<br />

Cord-infant blood Pb:<br />

Correlation coefficient = 0.77, ∃ = 0.90<br />

No significant differences in maternal blood to<br />

cord blood ratios in low birth weight and normal<br />

birth weight infants.<br />

Correlation coefficient = 0.55


AX6-170<br />

Table AX6-6.1 (cont’d). Placental Transfer <strong>of</strong> <strong>Lead</strong> from Mother to Fetus<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Fahim et al. (1976)<br />

Missouri<br />

249 mother-infant pairs from Columbia.<br />

Samples also collected from 253 mothers<br />

from Rolla who delivered near Pb mining<br />

areas.<br />

Term pregnancies:<br />

Columbia (n = 240):<br />

Maternal blood Pb:<br />

Mean 13.1 µg/100 g (SE 0.31)<br />

Fetal blood Pb:<br />

Mean 4.3 µg/100 g (SE 0.10)<br />

Placenta blood Pb:<br />

Mean 7.0 µg/100 g (SE 0.01)<br />

Cord blood Pb:<br />

Mean 11.0 µg/100 g (SE 0.31)<br />

Rolla (n = 177):<br />

Maternal blood Pb:<br />

Mean 14.3 µg/100 g (SE 0.16)<br />

Fetal blood Pb:<br />

Mean 4.6 µg/100 g (SE 0.08)<br />

Placenta blood Pb:<br />

Mean 8.0 µg/100 g (SE 0.06)<br />

Cord blood Pb:<br />

Mean 11.0 µg/100 g (SE 0.14)<br />

Maternal-fetal blood Pb:<br />

Correlation coefficient = 0.29


AX6-171<br />

Table AX6-6.1 (cont’d). Placental Transfer <strong>of</strong> <strong>Lead</strong> from Mother to Fetus<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Gershanik et al.<br />

(1974)<br />

Shreveport, LA<br />

Europe<br />

Graziano et al.<br />

(1990)<br />

Kosovo, Yugoslavia<br />

Huel et al. (1981)<br />

France<br />

Lauwerys et al.<br />

(1978); Roels et al.<br />

(1978) Belgium<br />

Barltrop (1969)<br />

England<br />

98 mother-infant pairs. Maternal blood Pb during labor:<br />

Mean 10.3 µg/dL<br />

902 births in Titova Mitrovica, site <strong>of</strong> a<br />

large Pb smelter, refinery, and battery<br />

factory, and Pristina, a non-Pb-exposed<br />

control town.<br />

Hair sample pairs (n = 100) from mothers<br />

and newborns at time <strong>of</strong> delivery.<br />

474 mother-infant pairs from Antwerp,<br />

Brussels, Leuven, Tournai, and Vilvoorde.<br />

Cord blood Pb:<br />

Mean 10.1 µg/dL<br />

Maternal blood Pb at mid-pregnancy:<br />

Geometric means:<br />

Titova Mitrovica 17.1 µg/dL (95% CI:<br />

16.9, 42.6)<br />

Pristina 5.1 µg/dL (95% CI: 2.5, 10.6)<br />

Maternal hair Pb:<br />

Geometric mean 8.5 µg/dL<br />

Fetal hair Pb:<br />

Geometric mean 7.3 µg/dL<br />

Maternal blood Pb:<br />

Mean 10.1 µg/dL (range 3.1-31)<br />

Infant blood Pb:<br />

Mean 8.3 µg/dL (range 2.7-27.3)<br />

29 paired maternal and fetal samples. Maternal blood Pb:<br />

Mean 13.9 µg/100 g<br />

Placenta blood Pb:<br />

Median 7.5 µg/100 g wet weight (range 1.1-39.5)<br />

Cord blood Pb:<br />

Mean 10.8 µg/100 g<br />

Correlation coefficient = 0.64<br />

Maternal blood Pb at delivery and cord<br />

blood Pb:<br />

Correlation coefficient = 0.920, ∃ = 0.928<br />

Correlation coefficient = 0.24<br />

Maternal-infant blood Pb:<br />

Correlation coefficient = 0.81, ∃ = 0.73<br />

ln placenta-maternal blood Pb:<br />

Correlation coefficient = 0.22<br />

ln placenta-infant blood Pb:<br />

Correlation coefficient = 0.28<br />

Correlation coefficient = 0.86


AX172<br />

Table AX6-6.1 (cont’d). Placental Transfer <strong>of</strong> <strong>Lead</strong> from Mother to Fetus<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Barltrop (1969)<br />

England<br />

Latin America<br />

Chuang et al. (2001)<br />

Mexico City, Mexico<br />

34 fetuses at gestational age 10 to 40 wks<br />

obtained from termination <strong>of</strong> pregnancy and<br />

neonatal deaths.<br />

615 women recruited in 1994-1995.<br />

Investigators used structural equation<br />

modeling to estimate plasma Pb as the<br />

unmeasured variable and to quantify the<br />

interrelations <strong>of</strong> cord blood Pb with plasma<br />

Pb, whole blood Pb, and bone Pb (cortical<br />

and trabecular).<br />

Blood Pb levels in femur, liver, blood, brain, heart,<br />

and kidney measured.<br />

Maternal whole blood Pb:<br />

Mean 8.45 µg/dL (SD 3.94)<br />

Maternal patella bone Pb:<br />

Mean 14.24 µg/g bone mineral (SD 14.19)<br />

Maternal tibia bone Pb:<br />

Mean 9.67 µg/g bone mineral (SD 9.21)<br />

Cord blood Pb:<br />

Mean 6.55 µg/dL (SD 3.45)<br />

Pb became detectable at gestational age 12 -14<br />

wks. For skeletal (femur) and s<strong>of</strong>t tissue with<br />

high affinity (liver), Pb levels increased<br />

progressively until term. In contrast, in s<strong>of</strong>t<br />

tissue with low affinity (heart), only a modest<br />

increase in Pb levels was observed between 14<br />

wks and term.<br />

ln cord-ln maternal whole blood Pb:<br />

Correlation coefficient = 0.82<br />

ln cord-ln maternal plasma Pb:<br />

Correlation coefficient = 0.89<br />

ln cord-maternal patella Pb:<br />

Correlation coefficient = 0.23<br />

ln cord-maternal tibia Pb:<br />

Correlation coefficient 0.18<br />

The structural equation models indicated that<br />

maternal plasma Pb had a stronger association<br />

with fetal cord blood Pb compared to that <strong>of</strong><br />

whole blood Pb. In addition, the models<br />

suggested a significant contribution <strong>of</strong> Pb from<br />

the skeletal system to plasma during pregnancy,<br />

a contribution that is independent <strong>of</strong> the<br />

influence <strong>of</strong> maternal whole blood Pb.


AX6-173<br />

Table AX6-6.1 (cont’d). Placental Transfer <strong>of</strong> <strong>Lead</strong> from Mother to Fetus<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Other Locations<br />

Clark (1977)<br />

Zambia<br />

Casey and Robinson<br />

(1978)<br />

New Zealand<br />

122 mother-infant pairs residing near the<br />

Broken Hill Pb Mine and Smelter. Control<br />

group <strong>of</strong> 31 mother-infant pairs.<br />

40 fetuses (23 stillborn and 17 died within<br />

24 hrs), 22 to 43 wks gestation.<br />

Chaube et al. (1972) 50 embryos and fetuses 31 to 261 days<br />

gestational age that were aborted.<br />

Mine group:<br />

Maternal blood Pb:<br />

Mean 41.2 µg/dL (SD 14.4)<br />

Infant cord blood Pb:<br />

Mean 37.0 µg/dL (SD 15.3)<br />

Control group:<br />

Maternal blood Pb:<br />

Mean 14.7 µg/dL (SD 7.5)<br />

Infant cord blood Pb:<br />

Mean 11.8 µg/dL (SD 5.6)<br />

Pb detected in 73% <strong>of</strong> liver, 23% <strong>of</strong> kidneys, 40%<br />

<strong>of</strong> brain, 25% <strong>of</strong> heart, 33% skeletal muscle, and<br />

70% <strong>of</strong> bone samples. Pb also detected in 11 <strong>of</strong> 14<br />

lung samples (79%).<br />

Overall Pb concentration in s<strong>of</strong>t tissue:<br />

0.1-2.4 µg/g dry matter<br />

Pb concentration in bone samples:<br />

0.4-4.3 µg/g dry matter<br />

Among the 1st trimester specimens:<br />

Pb detected in 77% <strong>of</strong> liver, 15% <strong>of</strong> brain, and 30%<br />

<strong>of</strong> kidney samples.<br />

Mine group:<br />

Correlation coefficient = 0.77<br />

Control group:<br />

Correlation coefficient = 0.56<br />

Pb concentrations in bone were higher than in<br />

the other tissues.<br />

Levels in brain, heart, and muscle similar to<br />

values reported <strong>for</strong> children and adults. Levels<br />

in liver, kidney, lung, and bone were much less<br />

than adult values, suggesting much <strong>of</strong> the Pb that<br />

enters the body after birth accumulates in these<br />

tissues.<br />

Placental transfer occurs as early as the 1st<br />

trimester <strong>of</strong> pregnancy.


AX6-174<br />

Table AX6-6.2. <strong>Lead</strong> Exposure and Male Reproduction: Semen <strong>Quality</strong><br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Ben<strong>of</strong>f et al. (2003a)<br />

New York<br />

Ben<strong>of</strong>f et al. (2003b)<br />

New York<br />

Cullen et al. (1984)<br />

U.S.<br />

74 male partners <strong>of</strong> women undergoing<br />

their first in vitro fertilization cycle.<br />

15 semen donors in an artificial<br />

insemination program. None were<br />

occupationally exposed to Pb.<br />

Seven men with symptomatic occupational<br />

Pb intoxication.<br />

Seminal plasma Pb:<br />

Mean 39.50 µg/dL (SD 35.97)<br />

Seminal plasma Pb:<br />

Range 150 µg/dL<br />

Maximum whole blood Pb levels:<br />

66-139 µg/dL<br />

Significant negative correlation between seminal<br />

plasma Pb and fertilization rate (r = !0.447).<br />

Statistically significant inverse correlations (r<br />

values <strong>of</strong>


AX6-175<br />

Table AX6-6.2 (cont’d). <strong>Lead</strong> Exposure and Male Reproduction: Semen <strong>Quality</strong><br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Canada<br />

Alexander et al.<br />

(1996a)<br />

British Columbia<br />

119 workers employed at a Pb smelter. Current blood Pb:<br />

Mean 22.4 µg/dL (range 5-58)<br />

Sperm concentration and total sperm count were<br />

inversely related to current blood Pb<br />

concentration, with the largest effects detected<br />

among men with blood Pb concentrations <strong>of</strong> 40<br />

µg/dL or more.<br />

Geometric mean<br />

Blood Pb (µg/dL) sperm count×10 6<br />


AX6-176<br />

Table AX6-6.2 (cont’d). <strong>Lead</strong> Exposure and Male Reproduction: Semen <strong>Quality</strong><br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Bonde et al. (2002)<br />

UK, Belgium, Italy<br />

Assennato et al.<br />

(1986)<br />

Italy<br />

Lancranjan et al.<br />

(1975)<br />

Europe<br />

European study <strong>of</strong> 503 men (362 exposed to<br />

Pb, 141 unexposed controls) employed in<br />

Pb industry.<br />

18 battery workers (exposed group) and 18<br />

cement workers (control group).<br />

150 men occupationally exposed to Pb<br />

divided into four groups: Pb-poisoned<br />

workmen (n = 23) and those showing a<br />

moderate (n = 42), slight (n = 35), or<br />

physiologic absorption (n = 50).<br />

Blood Pb:<br />

Exposed workers:<br />

Mean 31.0 µg/dL (range 4.6-64.5)<br />

Unexposed workers:<br />

Mean 4.4 µg/dL<br />

Blood Pb:<br />

Battery workers:<br />

Mean 61 µg/dL (SD 20)<br />

Cement workers:<br />

Mean 18 µg/dL (SD 5)<br />

Semen Pb:<br />

Battery workers:<br />

Mean 79 µg/dL (SD 36)<br />

Cement workers:<br />

Mean 22 µg/dL (SD 9)<br />

Blood Pb:<br />

Pb poisoned workers:<br />

Mean 74.5 µg/dL<br />

Moderately exposed workers:<br />

Mean 52.8 µg/dL<br />

Median sperm concentration reduced by 49% in<br />

men with blood Pb levels >50 µg/dL.<br />

Odds ratio <strong>for</strong> sperm count #50 million/ml in<br />

men with blood Pb levels >50 µg/dL compared<br />

to


AX6-177<br />

Table AX6-6.2 (cont’d). <strong>Lead</strong> Exposure and Male Reproduction: Semen <strong>Quality</strong><br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Hernandez-Ochoa<br />

et al. (2005)<br />

Region Lagunera,<br />

Mexico<br />

Lerda (1992)<br />

Argentina<br />

Asia<br />

Chowdhury et al.<br />

(1986)<br />

India<br />

68 environmentally-exposed men residing<br />

in Torreón, Gómez Palacio, and Lerdo <strong>for</strong><br />

at least 3 yrs.<br />

38 male workers exposed to Pb in a battery<br />

factory and 30 controls.<br />

Ten men occupationally exposed to Pb in a<br />

printing press.<br />

Blood Pb:<br />

Geometric mean 9.3 µg/dL (range 2-24)<br />

Seminal fluid Pb:<br />

Geometric mean 2.02 µg/L (range 1.14-12.4)<br />

Pb in spermatozoa:<br />

Geometric mean 0.047 ng/10 6 cells (range 0.032-<br />

0.245)<br />

Blood Pb:<br />

A (n = 12): mean 86.6 µg/dL (SD 0.6)<br />

B (n = 11): mean 65.9 µg/dL (SD 1.6)<br />

C (n = 15): mean 48.6 µg/dL (SD 4.2)<br />

Controls (n = 30): mean 23.5 µg/dL (SD 1.4)<br />

Blood Pb:<br />

Exposed group:<br />

Mean 42.5 µg/dL<br />

Unexposed group:<br />

Mean 14.8 µg/dL<br />

Decreased sperm concentration, motility, normal<br />

morphology and viability correlated with Pb in<br />

spermatozoa. Reduced semen volume associated<br />

with seminal fluid Pb.<br />

Multiple linear regression indicated that<br />

percentages <strong>of</strong> progressive motility and<br />

morphology were the most sensitive parameters<br />

to Pb toxicity, which showed the highest<br />

percentages <strong>of</strong> abnormality among the semen<br />

quality parameters<br />

evaluated.<br />

No associations were found with blood Pb.<br />

Decreased sperm count, decreased percent<br />

motility, and increased percent with abnormal<br />

morphology observed in all three exposure<br />

groups compared to control group.<br />

Decrease in sperm count, percent motility and<br />

increase in number <strong>of</strong> sperm with abnormal<br />

morphology observed in these semen samples.


AX6-178<br />

Table AX6-6.3. <strong>Lead</strong> Exposure and Male Reproduction: Time to Pregnancy<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

J<strong>of</strong>fe et al. (2003)<br />

Belgium, England,<br />

Finland, Italy<br />

Apostoli et al. (2000)<br />

Italy<br />

Asclepios Project, large European<br />

collaborative cross-sectional study.<br />

1,108 men (638 occupationally exposed to<br />

Pb at the time <strong>of</strong> pregnancy) who have<br />

fathered a child.<br />

Italian men included in the Asclepios<br />

project. 251 exposed men and 45<br />

unexposed men with at least one completed<br />

pregnancy.<br />

Blood Pb:<br />

Belgium: mean 31.7 µg/dL<br />

England: mean 37.2 µg/dL<br />

Finland: mean 29.3 µg/dL<br />

Italy: mean 29.2 µg/dL<br />

Blood Pb distribution among exposed men:<br />

Percentage<br />

Blood Pb (µg/dL) <strong>of</strong> population<br />

0-19 14%<br />

20-29 40%<br />

30-39 32%<br />

∃40 14%<br />

Fecundity density<br />

Blood Pb (µg/dL) ratios (95% CI)<br />

control 1.00<br />


AX6-179<br />

Table AX6-6.3 (cont’d). <strong>Lead</strong> Exposure and Male Reproduction: Time to Pregnancy<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Sallmϑn et al.<br />

(2000a)<br />

Finland<br />

Asia<br />

Shiau, et al. (2004)<br />

Taiwan<br />

502 occupationally exposed males<br />

monitored by the Finnish Institute <strong>of</strong><br />

Occupational Health.<br />

280 pregnancies in 133 couples in which<br />

male partner employed in battery plant.<br />

127 conceived during exposure; remainder<br />

conceived prior to exposure.<br />

Blood Pb distribution (available close to time <strong>of</strong><br />

conception in 62% <strong>of</strong> men; in 38% estimated based<br />

on blood Pb levels obtained at other times or based<br />

on job histories):<br />

Percentage<br />

Blood Pb (µg/dL) <strong>of</strong> population<br />


AX6-180<br />

Table AX6-6.4. <strong>Lead</strong> Exposure and Male Reproduction: Reproductive History<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Lin et al. (1996)<br />

New York<br />

Europe<br />

Gennart et al. (1992)<br />

Belgium<br />

Bonde and Kolstad<br />

(1997)<br />

Denmark<br />

4,256 male workers reported to the New<br />

York State Heavy Metals Registry<br />

(exposed) and 5,148 male bus drivers from<br />

the New York State Department <strong>of</strong> Motor<br />

Vehicles file (control), frequency-matched<br />

<strong>for</strong> age and residence. Fertility during the<br />

period <strong>of</strong> 1981 to 1992. Records linked to<br />

birth certificates from the New York State<br />

Office <strong>of</strong> Vital Statistics.<br />

74 men occupationally exposed to Pb <strong>for</strong><br />

more than 1 yr and 138 men in reference<br />

group with no occupational exposure.<br />

1,349 male employees ages 20-49 yrs from<br />

three battery plants and control group <strong>of</strong><br />

9,656 men not employed in Pb industry.<br />

Cohorts identified by records in a national<br />

pension fund. In<strong>for</strong>mation on births<br />

obtained from Danish Population Register.<br />

Blood Pb in Pb-exposed men:<br />

Mean 37.2 µg/dL (SD 11.1)<br />

Blood Pb in Pb-exposed men:<br />

Mean 40.3 µg/dL<br />

Duration <strong>of</strong> Pb exposure:<br />

Mean 10.7 yrs<br />

Blood Pb in subset <strong>of</strong> battery worker cohort (4,639<br />

blood samples from 400 workers):<br />

Mean 35.9 µg/dL (SD 13.0)<br />

Standardized fertility ratio <strong>of</strong> Pb-exposed men in<br />

comparison with non-exposed men was 0.88<br />

(95% CI: 0.81, 0.95).<br />

Exposed group had fewer births than expected.<br />

Among those employed in Pb industry over<br />

5 yrs, a relative risk <strong>of</strong> 0.38 (95% CI: 0.23,<br />

0.61) was observed after adjusting <strong>for</strong> age, race,<br />

education, and residence.<br />

Compared to reference group, odds <strong>of</strong> at least<br />

one live birth reduced in exposed group during<br />

the period <strong>of</strong> Pb exposure (odds ratio <strong>of</strong> 0.65<br />

[95% CI: 0.43, 0.98]).<br />

Fertility decreased with increasing exposure<br />

(although number <strong>of</strong> men at higher exposure<br />

levels small).<br />

No associations found between exposure<br />

measure and birth rate.<br />

Relative risk comparing person yrs at risk from<br />

Pb exposure with yrs at risk in reference group<br />

was 0.88 (95% CI: 0.81, 0.95).


AX6-181<br />

Table AX6-6.4 (cont’d). <strong>Lead</strong> Exposure and Male Reproduction: Reproductive History<br />

Reference and<br />

Study Location Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Sallmϑn et al.<br />

(2000b)<br />

Finland<br />

Occupationally exposed males monitored<br />

by the Finnish Institute <strong>of</strong> Occupational<br />

Health. 2,111 individuals with probable<br />

exposure (a blood Pb level ∃10 µg/dL<br />

within a 5-yr time period including a<br />

calendar yr preceding the yr <strong>of</strong> marriage<br />

and 4 consecutive yrs) and 681 controls<br />

(with mean blood Pb levels


ANNEX TABLES AX6-7<br />

AX6-182


AX6-183<br />

Table AX6-7.1. Recent Studies <strong>of</strong> <strong>Lead</strong> Exposure and Genotoxicity<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings and Interpretation<br />

Europe<br />

Fracasso et al. (2002)<br />

Italy<br />

Case-control design.<br />

37 workers employed at a battery plant.<br />

29 student and <strong>of</strong>fice worker volunteers<br />

with no known occupational exposure to<br />

genotoxins.<br />

Peripheral lymphocytes isolated from<br />

whole blood.<br />

Reactive Oxygen Species (ROS)<br />

production, cellular GSH level, PKC<br />

iso<strong>for</strong>ms, and DNA breaks (via comet)<br />

assayed.<br />

ANOVA and logistic regression used to<br />

compare workers vs. healthy volunteers.<br />

Adjusted <strong>for</strong> age, alcohol use, and<br />

smoking.<br />

Battery plant workers. Blood Pb<br />

categories used <strong>for</strong> some<br />

comparisons, with 35 µg/100mL as cutpoints.<br />

Mean blood Pb 39.6 µg/100mL <strong>for</strong><br />

workers, 4.4 µg/100mL <strong>for</strong><br />

volunteers.<br />

OR (95% CI)<br />

Workers vs. Volunteers:<br />

ROS: 1.43 (0.79, 2.60)<br />

DNA breaks (tail moment): 1.07 (1.02, 1.12)<br />

GSH: 0.64 (0.49, 0.82)<br />

PKC α reduced in workers, atypical PKC unchanged vs.<br />

volunteers (no statistics provided).<br />

Means (SE) via blood Pb category <strong>for</strong> ROS and GSH:<br />

35 µg/100 mL 5.4 (0.5) and 9.2 (1.2)<br />

Major analyses controlled <strong>for</strong> age, smoking, and alcohol intake.<br />

Analyses by blood Pb category not controlled <strong>for</strong> age, smoking,<br />

or alcohol intake but these factors said not to influence endpoint<br />

and/or results “significantly.” No control <strong>for</strong> potential<br />

coexposures.


AX6-184<br />

Table AX6-7.1 (cont’d). Recent Studies <strong>of</strong> <strong>Lead</strong> Exposure and Genotoxicity<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings and Interpretation<br />

Europe<br />

Palus et al. (2003)<br />

Poland<br />

Cross-sectional design.<br />

Battery plant workers: 34 acid battery,<br />

22 alkaline battery, and 52 plant<br />

personnel from departments with no<br />

known exposure to Pb or cadmium.<br />

Lymphocytes isolated from whole blood.<br />

SCE, MN, DNA damage (via comet)<br />

assayed.<br />

Means compared via ANOVA.<br />

Workers considered Pb-exposed if<br />

from acid battery department,<br />

cadmium-exposed if from alkaline,<br />

unexposed if from other department.<br />

Mean blood Pb 504 µg/L <strong>for</strong><br />

Pb-exposed workers, 57 µg/L <strong>for</strong><br />

cadmium-exposed, and 56 µg/L <strong>for</strong><br />

other workers.<br />

Mean (SD)<br />

Pb exposed workers (all combined):<br />

SCEs 7.48 (0.88)<br />

MN 18.63 (5.01)<br />

NDI 1.89 (no SD given)<br />

Cadmium exposed workers (all combined):<br />

SCEs 6.95 (0.79)<br />

MN 15.86 (4.92)<br />

NDI 1.96 (no SD given)<br />

Other workers (all combined):<br />

SCEs 6.28 (1.04)<br />

MN 6.55 (3.88)<br />

NDI 1.86 (no SD given)<br />

Elevation <strong>of</strong> SCEs and MN vs. controls at p < 0.05 and<br />

p < 0.01, respectively.<br />

Both SCEs and MN elevated among Pb-exposed workers as well<br />

as cadmium-exposed workers compared to controls. Differences<br />

greatest <strong>for</strong> Pb-exposed workers.<br />

Higher SCE and MN also occurred among Pb-exposed workers<br />

after stratification by smoking status.<br />

No direct control <strong>for</strong> potential coexposures, but mean blood<br />

cadmium no higher in Pb-exposed than in other worker group.


AX6-185<br />

Table AX6-7.1 (cont’d). Recent Studies <strong>of</strong> <strong>Lead</strong> Exposure and Genotoxicity<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Van Larebeke et al.<br />

(2004)<br />

Belgium<br />

Latin America<br />

Minozzo et al. (2004)<br />

Brazil<br />

Cross-sectional design.<br />

99 female nonsmokers, ages 50-65,<br />

drawn from rural and industrial areas.<br />

Peripheral lymphocytes isolated from<br />

blood. HPRT variant frequency<br />

determined.<br />

Cross-sectional design.<br />

26 workers employed at a battery<br />

recyclery <strong>for</strong> 0.5 to 30 yrs.<br />

29 healthy volunteers <strong>of</strong> similar age<br />

range and SES.<br />

Peripheral lymphocytes isolated from<br />

whole blood.<br />

Fixed blood slides stained with Giemsa<br />

visually evaluated to determine<br />

micronuclear frequency (MN) and<br />

cellualr proliferation as nuclear<br />

division index (NDI).<br />

ANOVA and logistic regression used<br />

to compare workers vs. healthy<br />

volunteers. Adjusted <strong>for</strong> age, alcohol<br />

use, and smoking.<br />

Pb concentration measured in blood<br />

(serum).<br />

Women also classified as above vs.<br />

below median <strong>for</strong> blood Pb.<br />

Battery recyclery workers were<br />

considered exposed.<br />

Blood Pb also determined.<br />

Mean blood Pb 35.4 µg/dL <strong>for</strong><br />

workers, 2.0 µg/dL <strong>for</strong> volunteers.<br />

HPRT variant frequency<br />

Above median serum Pb: 9.45 Η 10 -6<br />

Below median serum Pb: 5.21 Η 10 -6<br />

P-value <strong>for</strong> difference = 0.08 adjusted <strong>for</strong> age, education,<br />

smoking, BMI, and serum selenium. (Significant inverse<br />

association noted between variant frequency and serum<br />

selenium.) Uncontrolled <strong>for</strong> potential exposure to other<br />

genotoxins.<br />

Means (SD) <strong>for</strong> workers and volunteers<br />

MN: 3.85 (2.36) and 1.45 (1.43)<br />

NDI: 1.77 (0.22) and 1.89 (0.18)<br />

Kendal correlation coefficient:<br />

All workers {assuming recyclery workers only, not total<br />

population, but no population number given in table.}<br />

Blood Pb Η MN: 0.061 (p = 0.33)<br />

Blood Pb Η NDI: 0.385 (p = 0.003)<br />

Not controlled <strong>for</strong> age or SES, although worker and volunteer<br />

populations said to be <strong>of</strong> similar age and SES. Uncontrolled <strong>for</strong><br />

potential coexposures. Correlations appear uncontrolled <strong>for</strong><br />

smoking, age, or other factors. Differences in MN and NDI<br />

minor <strong>for</strong> smokers vs. nonsmoker, however. Diet “type”<br />

“similar” <strong>for</strong> workers and controls, although no definition <strong>of</strong><br />

similarity provided.


AX6-186<br />

Table AX6-7.2. Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period<br />

United States<br />

Study Description Pb Measurement Findings and Interpretation<br />

Steenland et al. (1992)<br />

(follow-up <strong>of</strong> Selevan<br />

et al. (1985)<br />

U.S.<br />

1940-1988<br />

Wong and Harris<br />

(2000)<br />

(follow-up <strong>of</strong> Cooper<br />

et al. (1985)<br />

U.S.<br />

1947-1995<br />

Cohort design.<br />

1,990 male workers employed <strong>for</strong><br />

at least 1 yr in a Pb-exposed<br />

department at a U.S. Pb smelter<br />

in Idaho during 1940-1965.<br />

Mortality traced through 1988 to<br />

determine cause <strong>of</strong> death.<br />

SMR computed <strong>for</strong> workers vs.<br />

national rates <strong>for</strong> age-comparable<br />

counterparts.<br />

Cohort design.<br />

Pb battery plant (4,518) and smelter<br />

(2,300) workers.<br />

Worker mortality was followed up<br />

through 1995.<br />

Cause <strong>of</strong> death was identified from<br />

death certificates.<br />

Mortality was compared with U.S.<br />

national age-, calendar-yr-, and genderspecific<br />

rates to compute the SMR.<br />

(See additional entry <strong>for</strong> nested study<br />

<strong>of</strong> stomach cancer.)<br />

Exposure categorizations based on<br />

airborne Pb measurements from<br />

1975 survey. High-Pb-exposure<br />

subgroup consisted <strong>of</strong> 1,436 workers<br />

from departments with an avg <strong>of</strong> least<br />

0.2 mg/m 3 airborne Pb or ≥50% <strong>of</strong><br />

jobs showing 0.40 mg/m 3 or greater.<br />

Mean blood Pb 56 µg/dL in 1976.<br />

Workers were evaluated as a whole,<br />

and also as separate battery plant and<br />

smelter worker populations.<br />

Job histories were also used to<br />

stratify workers by cumulative yrs <strong>of</strong><br />

employment (1-9, 10-19, 20+), date<br />

<strong>of</strong> hire (pre-1946 vs. 1946 on), and<br />

lag between exposure and cancer<br />

(34 yrs). Mean blood<br />

Pb 80 µg/dL during 1947-72 among<br />

smelter workers, 63 µg/dL among<br />

battery workers.<br />

SMR (95% CI); number <strong>of</strong> deaths<br />

Total cohort:<br />

Nonsignificantly elevated RRs: kidney, bladder, stomach, and lung<br />

cancer.<br />

High-Pb-exposure subgroup:<br />

Kidney 2.39 (1.03, 4.71); 8<br />

Bladder 1.33 (0.48, 2.90); 6<br />

Stomach 1.28 (0.61, 2.34); 10<br />

Lung 1.11 (0.82, 1.47); 49<br />

No control <strong>for</strong> smoking or exposure to other metals.<br />

SMR (95% CI)<br />

Battery plant workers:<br />

All cancer 1.05 (0.97, 1.13)<br />

All respiratory 1.13 (0.98, 1.29)<br />

Stomach 1.53 (1.12, 2.05)<br />

Lung, trachea, bronchus 1.14 ( 0.99, 1.30)<br />

Thyroid, Hodgkin’s: nonsignificant<br />

Bladder 0.49 (0.23, 0.90)<br />

Smelter workers:<br />

Digestive, respiratory, thyroid: nonsignificant<br />

Lung 1.22 (1.00, 1.47)<br />

Battery plant and smelter workers combined:<br />

All cancer 1.04 (0.97, 1.11)<br />

All respiratory 1.15 (1.03, 1.28)<br />

Stomach 1.47 (1.13, 1.90)<br />

Lung, trachea, bronchus 1.16 ( 1.04, 1.30)<br />

Thyroid/endocrine 3.08 (1.33, 6.07)<br />

Lung and stomach risks lower pre-1946 hires; higher <strong>for</strong> workers<br />

employed 10-19 yrs than 19 yrs; SMRs peaked<br />

with 20- to 34-yr latency <strong>for</strong> lung, but


AX6-187<br />

Table AX6-7.2 (cont’d). Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

United States (cont’d)<br />

Wong and Harris<br />

(2000)<br />

U.S.<br />

1947-1995.<br />

(Nested in Wong and<br />

Harris 200 cohort.)<br />

Europe<br />

Fanning (1988)<br />

(Cases overlap those<br />

occurring in<br />

Dingwall-Fordyce and<br />

Lane, 1963; and<br />

Malcolm and Barnett,<br />

1982).<br />

U.K.<br />

1926-1985<br />

Case-control design.<br />

Cases: the 30 stomach cancer cases<br />

occurring in a Philadelphia Pb battery<br />

plant.<br />

Controls: 120 age-matched cohort<br />

members.<br />

Mean exposure was compared <strong>for</strong><br />

cases vs. controls. Odds <strong>of</strong> exposure<br />

were also computed <strong>for</strong> increasing<br />

quartiles <strong>of</strong> cumulative exposure.<br />

Proportional mortality/cohort design.<br />

Subjects: 2,073 deceased males<br />

identified through pension records <strong>of</strong><br />

Pb battery and other factory workers in<br />

the U.K.<br />

Workers dying from a specific cancer<br />

were compared with workers dying<br />

from all other causes<br />

Job titles were used to classify Pb<br />

exposure as low, intermediate, or<br />

high; total mos <strong>of</strong> any exposure, <strong>of</strong><br />

intermediate or high exposure only,<br />

and <strong>of</strong> cumulative exposure, with<br />

mos weighted by 1, 2, or 3 if spent in<br />

low-, intermediate-, or high-exposure<br />

job.<br />

Workers were classified as High or<br />

moderate Pb exposure vs. little or no<br />

exposure based on job titles.<br />

Mean mos <strong>of</strong> employment, <strong>of</strong> intermediate or high exposure, or <strong>of</strong><br />

weighted exposure to Pb were all nonsignificantly lower among<br />

cases.<br />

OR <strong>for</strong> cumulative weighted exposure in the 10 yrs prior to death:<br />

1st quartile 1.00<br />

2nd quartile 0.62<br />

3rd quartile 0.82<br />

4th quartile 0.61<br />

p <strong>for</strong> trend = 0.47; ORs showed no positive association with<br />

any index <strong>of</strong> exposure.<br />

Analyses appear uncontrolled <strong>for</strong> smoking, other occupational<br />

exposures, or other risk factors.<br />

OR (95% CI); number <strong>of</strong> deaths<br />

Lung cancer: 0.93 (0.8, 1.1); 76<br />

Stomach cancer: 1.34; 31<br />

No associations <strong>for</strong> other cancer types; elevations in stomach and<br />

total digestive cancers limited to the period be<strong>for</strong>e 1966.


AX6-188<br />

Table AX6-7.2 (cont’d). Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Anttila et al. (1995)<br />

Finland<br />

1973-1988<br />

Cohort plus case-referent design.<br />

20,700 workers with at least one blood<br />

Pb measurement between 1973 and<br />

1983.<br />

Workers were linked to the Finnish<br />

Cancer Registry <strong>for</strong> follow-up through<br />

1988. For deceased workers, cause <strong>of</strong><br />

death was identified from death<br />

certificate.<br />

Mortality and incidence were compared<br />

with gender-, 5-yr age, and 4-yr<br />

calendar-yr matched national rates.<br />

Exposure was categorized according<br />

to the highest peak blood level<br />

measured:<br />

Low: 0-0.9 µmol/L<br />

(0-18.6 µg/dL)<br />

Moderate: 1-1.9 µmol/L<br />

(20.7-39.4 µg/dL)<br />

High: 2-7.8 µmol/L<br />

(41.4-161.6 µg/dL)<br />

Mean blood Pb 26 µg/dL.<br />

Total cohort:<br />

No elevation in total or site-specific cancer mortality.<br />

Moderately exposed:<br />

Total respiratory and lung cancer:<br />

SIR = 1.4 (95% CI: 1.0, 1.9) <strong>for</strong> both<br />

Total digestive, stomach, bladder, and nervous system:<br />

nonsignificant elevations.<br />

Highly exposed:<br />

No increase in risks.<br />

All cancer:<br />

RR = 1.4 (95% CI: 1.1, 1.8)<br />

Lung or tracheal:<br />

RR = 2.0 (95% CI: 1.2, 3.2)<br />

No increase in high-exposure group.<br />

No RRs reported <strong>for</strong> other cancers.<br />

Case-referent substudies:<br />

Lung cancer ORs increased with increasing cumulative<br />

exposure to Pb.<br />

Highly exposed: squamous-cell lung cancer OR <strong>of</strong> 4.1<br />

(95% CI: 1.1, 15) after adjustment <strong>for</strong> smoking.<br />

Short follow-up period limits statistical power, <strong>of</strong>fset to a<br />

large degree by the substantial sample size. No control <strong>for</strong><br />

exposure to other potential carcinogens.


AX6-189<br />

Table AX6-7.2 (cont’d). Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period<br />

Europe (cont’d)<br />

Study Description Pb Measurement Findings and Interpretation<br />

Anttila et al. (1996)<br />

Finland<br />

1973-1988<br />

(Nested analysis based<br />

on Antilla et al., 1995<br />

cohort)<br />

Gerhardsson et al.<br />

(1995)<br />

Sweden<br />

1969-1989<br />

Case-control design.<br />

(See Anttila et al., 1995 <strong>for</strong> basic<br />

in<strong>for</strong>mation on the source population.)<br />

Cases: 26 Finnish men with CNS<br />

cancer.<br />

Controls: 200 Finnish men without<br />

CNS cancer.<br />

Nested case-control analysis.<br />

Cohort design.<br />

684 male Swedish secondary Pb smelter<br />

workers with Pb exposure.<br />

Cancer incidence among workers was<br />

traced through 1989.<br />

Incidence was compared with county<br />

rates.<br />

Peak blood Pb levels used to<br />

categorize exposure as 0.1-0.7,<br />

0.8-1.3, and 1.4-4.3 µg/L.<br />

Cumulative exposure estimated by<br />

using mean annual blood Pb level to<br />

categorize exposure as 0, 1-6, 7-14,<br />

or 15-49 µg/L.<br />

Interviews were used to obtain<br />

occupational history and other riskfactor<br />

data from patients or next<br />

<strong>of</strong> kin.<br />

Blood Pb level: any worker with a<br />

detectable blood Pb level was<br />

classified as exposed.<br />

Number <strong>of</strong> cases or deaths<br />

CNS cancer incidence (26 cases): Rose with increasing peak lifetime<br />

blood Pb measurements; not significant.<br />

Glioma mortality (16 deaths): Rose consistently and significantly<br />

with peak and mean blood Pb level, duration <strong>of</strong> exposure, and<br />

cumulative exposure.<br />

Mortality by cumulative exposure, controlled <strong>for</strong> cadmium, gasoline,<br />

and yr monitoring began:<br />

Low (13 subjects) 2.0 (2)<br />

Medium (14 subjects) 6.2 (2)<br />

High (16 subjects) 12.0 (5)<br />

One death among 26 subjects with no exposure: test <strong>for</strong> trend<br />

significant at p = 0.02.<br />

Controlled <strong>for</strong> smoking as well as exposure to cadmium and gasoline.<br />

Complete follow-up with minimal disease misclassification.<br />

SIR (95% CI); number <strong>of</strong> cases<br />

All malignancies:<br />

1.27 (0.91, 1.74); 40<br />

Respiratory:<br />

1.32 (0.49, 2.88); 6<br />

All gastrointestinal:<br />

Cohort 1.84 (0.92, 3.29); 11<br />

Highest quartile 2.34 (1.07, 4.45); 9<br />

Stomach:<br />

1.88 (0.39, 5.50); 3<br />

Colon:<br />

1.46 (0.30, 4.28); 3<br />

SIRs <strong>for</strong> all other sites except brain were nonsignificantly elevated;<br />

too few cases.<br />

No control <strong>for</strong> smoking. Small numbers, so meaningful doseresponse<br />

analyses not possible <strong>for</strong> most cancer sites.


AX6-190<br />

Table AX6-7.2 (cont’d). Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Lundström et al.<br />

(1997)<br />

(follow-up <strong>of</strong><br />

Gerhardsson et al.<br />

(1986)<br />

(see also subcohort<br />

analyses <strong>of</strong> Englyst<br />

et al., 2001).<br />

Sweden<br />

1928-1987<br />

Englyst et al. (2001)<br />

(follow-up and subanalysis<br />

<strong>of</strong> Lundström<br />

et al., 1997).<br />

Sweden<br />

1928-1987<br />

Cohort design.<br />

3,979 copper and Pb smelter workers.<br />

Standardized mortality and incidence<br />

ratios were computed <strong>for</strong> workers<br />

compared with age-, yr-, gender-, and<br />

county-specific rates <strong>for</strong> the general<br />

population.<br />

Nested cohort analysis.<br />

Limited to 1,093 workers in the<br />

smelter’s Pb department, followed<br />

through 1997.<br />

Incidence was compared with county<br />

rates; age-specific SIRs with 15-yr lag.<br />

For some analyses, the entire cohort<br />

was treated as exposed. For others,<br />

job histories were used to single out<br />

1,992 workers belonging to<br />

departments thought to be exposed to<br />

“Pb only.” Mean blood Pb<br />

monitoring test results across time<br />

were used to single out a “highly<br />

exposed” group <strong>of</strong> 1,026 workers<br />

with blood Pb levels ≥10 µmol/L<br />

[≥207 µg/dL].<br />

Mean blood Pb 60 µg/dL in 1959.<br />

Workers were divided into<br />

Subcohorts I and <strong>II</strong> <strong>for</strong> ever and<br />

never worked in areas generally<br />

associated with exposure to arsenic<br />

or other known carcinogens (701 and<br />

383 workers, respectively).<br />

Detailed individual assessment <strong>of</strong><br />

arsenic exposure was made <strong>for</strong> all<br />

lung-cancer cases.<br />

SMR (95% CI); number <strong>of</strong> deaths<br />

Lung:<br />

Total cohort 2.8 (2.0, 3.8); 39<br />

Highly exposed 2.8 (1.8, 4.5); 19<br />

SIR (95% CI); number <strong>of</strong> cases<br />

Lung with 15-yr lag:<br />

Total cohort 2.9 (2.1, 4.0); 42<br />

Highly exposed 3.4 (2.2, 5.2); 23<br />

Pb-only 3.1 (1.7, 5.2); 14<br />

Pb-only highly exposed 5.1 (2.0, 10.5); 7<br />

Other highly exposed (total cohort), with 15-yr lag:<br />

Brain 1.6 (0.4, 4.2); 4<br />

Renal pelvis, ureter, bladder 1.8 (0.8, 3.4); 9<br />

Kidney 0.9 (0.2, 2.5); 3<br />

All cancer 1.1 (0.9, 1.4); 83<br />

No control <strong>for</strong> smoking.<br />

SIR (95% CI); number <strong>of</strong> cases<br />

Subcohort I (coexposed):<br />

Lung 2.4 (1.2, 4.5); 10<br />

Subcohort <strong>II</strong> (not coexposed):<br />

Lung 3.6 (1.2, 8.3); 5<br />

Subjects with lung cancer found to have history <strong>of</strong> “considerable”<br />

exposure to arsenic: 9/10 among Subcohort I, 4/5 among<br />

Subcohort <strong>II</strong>.<br />

No control <strong>for</strong> smoking.


AX6-191<br />

Table AX6-7.2 (cont’d). Key Occupational Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Carta et al. (2003)<br />

Sardinia<br />

1972-2001<br />

Cohort design.<br />

918 Pb smelter workers.<br />

Mortality traced from 1972 through<br />

2001.<br />

Standardized mortality ratios computed.<br />

Smelter workers considered exposed.<br />

Job histories also used to categorize<br />

degree <strong>of</strong> exposure based on<br />

environmental and blood Pb<br />

measurements <strong>for</strong> specific<br />

departments and tasks during<br />

1985-2001.<br />

SMR; number <strong>of</strong> cases<br />

Smelter workers as a whole<br />

All cancer 1.01; 108<br />

Gastric cancer 1.22; 4<br />

Lymphoma/leukemia 1.82; 6<br />

Lung cancer 1.21; 18<br />

Highly exposed workers<br />

Lung cancer 1.96 (95% CI: 1.02, 3.68) <strong>for</strong> highest exposure<br />

group, with statistically significant upward trend.<br />

Analyses <strong>for</strong> worker population as a whole supported by<br />

presence <strong>of</strong> dose-response pattern <strong>for</strong> lung cancer based on<br />

estimated exposure. Modest population size, inability to assess<br />

dose-response <strong>for</strong> cancers <strong>of</strong> interest other than lung. No control<br />

<strong>for</strong> smoking or other occupational exposures.


AX6-192<br />

Table AX6-7.3. Key Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer in the General Population<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

United States<br />

Jemal et al. (2002)<br />

(same cohort as in<br />

Lustberg and<br />

Silbergeld, 2002<br />

except <strong>for</strong> inclusion<br />

criteria)<br />

U.S.<br />

1976-1992.<br />

Cohort design.<br />

3,592 white participants from the<br />

1976-1980 NHANES <strong>II</strong> survey who<br />

had blood Pb measured at entry.<br />

Mortality was followed through 1992<br />

via NDI and SSADMF.<br />

RRs were calculated <strong>for</strong> the various<br />

exposure groups compared to survey<br />

participants with the lowest exposure,<br />

adjusted <strong>for</strong> age and smoking.<br />

Blood Pb (µg/dL) was measured<br />

by atomic absorption and used to<br />

classify subjects into exposure<br />

quartiles or groups above vs.<br />

below median exposure.<br />

Median blood Pb 12 µg/dL.<br />

RR (95% CI); number <strong>of</strong> deaths<br />

Lung (above vs. below median):<br />

Total cohort 1.5 (0.7, 2.9); 71<br />

Male 1.2 (0.6, 2.5); 52<br />

Female 2.5 (0.7, 8.4); 19<br />

Stomach (above vs. below median):<br />

Total cohort 2.4 (0.3, 19.1); 5<br />

Male 3.1 (0.3, 37.4); 4<br />

Female no deaths in referent group<br />

All cancer: total cohort by quartile (age-adjusted) 1.0, 1.2, 1.3, 1.5<br />

(p = 0.16 <strong>for</strong> trend).<br />

Smoking was controlled <strong>for</strong>. Pb levels occurring in the general population<br />

were examined, not just those in workers with high occupational exposure<br />

potential. Exposure to other carcinogens were not examined. Potential <strong>for</strong><br />

residual confounding by degree and duration <strong>of</strong> smoking exists (only<br />

controlled <strong>for</strong> never, <strong>for</strong>mer, current


AX6-193<br />

Table AX6-7.3 (cont’d). Key Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer in the General Population<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

United States<br />

Lustberg and<br />

Silbergeld (2002)<br />

(same cohort as Jemal<br />

et al., 2002 except <strong>for</strong><br />

inclusion criteria)<br />

U.S.<br />

1976-1992.<br />

Cohort design.<br />

4,190 U.S. participants from the 1976-<br />

1980 NHANES <strong>II</strong> health and nutrition<br />

survey who had blood Pb measured at<br />

entry and whose levels fell below<br />

30 µg/dL.<br />

Mortality was followed through 1992<br />

via NDI and SSADMF.<br />

RRs were calculated <strong>for</strong> the various<br />

exposure groups compared to survey<br />

participants with the lowest exposure,<br />

adjusted <strong>for</strong> age, smoking and other<br />

factors.<br />

Blood Pb (µg/dL) measured by<br />

atomic absorption was used to<br />

classify subjects into exposure<br />

groups:<br />

Low:


AX6-194<br />

Table AX6-7.4. Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

United States<br />

Mallin et al. (1989)<br />

Illinois<br />

1979-1984<br />

Cocco et al. (1998a)<br />

U.S.<br />

1984-1992<br />

Case-control design.<br />

Cases: random sample <strong>of</strong> 10,013 deaths<br />

from 7 specific cancers, identified from<br />

death certificates <strong>for</strong> Illinois males<br />

between 1979 and 1984.<br />

Controls: 3,198 randomly selected<br />

deaths from other causes.<br />

Odds <strong>of</strong> exposure computed <strong>for</strong> glass<br />

workers vs. other occupations.<br />

Case-control design.<br />

Cases: all 27,060 brain cancer deaths<br />

occurring among persons aged 35 or<br />

older during 1984-1992, from U.S.<br />

24-state death certificate registry.<br />

Controls: 4 gender-, race-, age-, and<br />

region-matched controls per case<br />

selected from deaths due to<br />

nonmalignant causes.<br />

Subjects were subdivided into 4 groups<br />

by gender and race (white or African-<br />

American) <strong>for</strong> all analyses.<br />

Exposure was based on<br />

occupations abstracted from<br />

death certificates.<br />

No specific measure <strong>of</strong> Pb<br />

exposure; glass workers can be<br />

considered potentially exposed.<br />

A job-exposure matrix was<br />

applied to death certificate-listed<br />

occupations to categorize<br />

persons as having low, medium,<br />

or high probability and intensity<br />

<strong>of</strong> exposure.<br />

Brain cancer, white male glass workers:<br />

OR = 3.0, p < 0.05<br />

No significant associations <strong>for</strong> other cancer sites.<br />

No control <strong>for</strong> smoking or other risk factors. Poor specificity <strong>for</strong> Pb<br />

exposure.<br />

Risk <strong>of</strong> brain cancer mortality increased consistently with intensity <strong>of</strong><br />

exposure among African-American males, but not other race-gender<br />

groups.<br />

Probability <strong>of</strong> exposure alone was not consistently associated with<br />

risk.<br />

In the high-probability group, risk increased with exposure intensity<br />

<strong>for</strong> all groups except African-American women (only 1 death in the<br />

high-probability group).<br />

Exposure estimate was based solely on occupation listed on death<br />

certificate, hence there was substantial opportunity <strong>for</strong><br />

misclassification.


AX6-195<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

United States (cont’d)<br />

Cocco et al. (1998b)<br />

U.S.<br />

1984-1992<br />

Case-control design.<br />

Cases: all 28,416 CNS cancer deaths<br />

occurring among persons aged 35 or<br />

older during 1984-1992, from U.S.<br />

4-state death certificate registry.<br />

Controls: 4 gender-, race-, age-, and<br />

region-matched controls per case<br />

selected from deaths due to<br />

nonmalignant causes.<br />

Subjects were subdivided into 4 groups<br />

by gender and race (white or African-<br />

American) <strong>for</strong> all analyses.<br />

Death certificate listed industry<br />

and occupation was used to<br />

categorize decedents. No<br />

estimates <strong>of</strong> Pb exposure<br />

specifically.<br />

OR (95% CI)<br />

All occupations or industries with ORs above 1.0 and p < 0.05 in at<br />

least one race-gender group were reported<br />

Newspaper printing and publishing industry:<br />

White male 1.4 (1.1, 1.8)<br />

Black male 3.1 (0.9, 10.9)<br />

Typesetting and compositing:<br />

White male 2.0 (1.1, 3.8)<br />

White female 1.3 (0.4, 3.8)<br />

Black female 4.2 (0.6, 30.7)<br />

No deaths among black males.<br />

Only two Pb exposure associated occupations or industries showed a<br />

statistically significant elevation <strong>of</strong> mortality. No specific measures<br />

<strong>of</strong> Pb exposure. Occupation based solely on death certificate, hence<br />

there was substantial opportunity <strong>for</strong> misclassification.


AX6-196<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

United States (cont’d)<br />

Cocco et al. (1999)<br />

U.S.<br />

1984-1996<br />

Case-control design.<br />

Cases: all 41,957 stomach cancer deaths<br />

occurring among persons aged 35 or<br />

older during 1984-1996, from U.S.<br />

24-state death certificate registry.<br />

Controls: 2 gender-, race-, age-, and<br />

region-matched controls per case<br />

selected from deaths due to<br />

nonmalignant causes.<br />

Subjects were subdivided into 4 groups<br />

by gender and race (white or African-<br />

American) <strong>for</strong> all analyses.<br />

A job-exposure matrix was<br />

applied to death certificatelisted<br />

occupations to categorize<br />

persons as having low, medium,<br />

or high probability and intensity<br />

<strong>of</strong> exposure.<br />

OR (95% CI)<br />

Adjusted <strong>for</strong> age, ethnicity, marital status, urban residence, and<br />

socioeconomic status.<br />

Elevated ORs:<br />

White female, high probability <strong>of</strong> exposure 1.53 (1.10, 2.12)<br />

Black male, high probability <strong>of</strong> exposure 1.15 (1.01, 1.32)<br />

Black female, high probability <strong>of</strong> exposure 1.76 (0.74, 4.16)<br />

Highly exposed group included 1,503 white and 453 black men and<br />

65 white and 10 black women; no pattern <strong>of</strong> increase across exposure<br />

levels.<br />

Intensity <strong>of</strong> exposure showed no association with stomach cancer<br />

except <strong>for</strong> black women:<br />

Low 1.82 (1.04, 3.18)<br />

Moderate 1.39<br />

High 1.25<br />

No control <strong>for</strong> other occupational exposures. Exposure estimate<br />

based on occupation listed on death certificate and hence subject to<br />

misclassification due to missing longest-held job.


AX6-197<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Canada<br />

Risch et al. (1988)<br />

Canada<br />

1979-1982<br />

Siemiatycki et al.<br />

(1991)<br />

Canada<br />

Case-control design.<br />

Cases: 826 Canadian men with<br />

histologically confirmed bladder cancer<br />

during 1979-1982.<br />

Controls: 792 controls from<br />

Canadian population, matched on age,<br />

gender, and area.<br />

Odds <strong>of</strong> exposure to Pb <strong>for</strong> cases vs.<br />

controls were computed, adjusted <strong>for</strong><br />

smoking and other risk factors.<br />

Case-control design.<br />

Cases: 3,730 various histologically<br />

confirmed cancers.<br />

Controls: specific cancer types were<br />

compared with other cancers as a control<br />

group, excluding lung cancer.<br />

Separate subgroup analysis was<br />

restricted to French Canadians.<br />

Subjects were interviewed<br />

regarding length <strong>of</strong><br />

occupational exposure to Pb<br />

compounds, as well as 17 other<br />

substances.<br />

Occupational exposure to<br />

293 substances, including Pb,<br />

was estimated from interviews.<br />

Exposure was classified as<br />

“any”; a subgroup with<br />

“substantial” exposure also was<br />

identified.<br />

OR (95% CI)<br />

61 men ever exposed to Pb (smoking-adjusted):<br />

2.0 (1.2, 3.5)<br />

Trend per 10 yrs duration <strong>of</strong> exposure:<br />

1.45 (1.09, 2.02)<br />

No other substances showed significant associations with bladder<br />

cancer.<br />

Controlled <strong>for</strong> smoking, marital status, socioeconomic status,<br />

education, ethnicity, and urban vs. rural residence.<br />

No control <strong>for</strong> other occupational exposures. Low control interview<br />

rate (53%), which could result in biased control sample.<br />

OR (90% CI); number <strong>of</strong> cases<br />

Any exposure to Pb:<br />

Lung 1.1 (0.9, 1.4); 326<br />

(French Canadians only)<br />

Stomach 1.2 (1.0, 1.6); 126<br />

Bladder 1.3 (1.0, 1.6); 155<br />

(French Canadians only)<br />

Kidney 1.2 (1.0, 1.6); 88<br />

ORs rose in the “substantial” exposure subgroup <strong>for</strong> stomach and<br />

lung, but not <strong>for</strong> bladder or kidney cancer.<br />

Controlled <strong>for</strong> smoking but not <strong>for</strong> other occupational exposures.


AX6-198<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe<br />

Sankila et al. (1990)<br />

Finland<br />

1941-1977<br />

Kauppinen et al.<br />

(1992)<br />

Finland<br />

1976-1981<br />

Cohort design.<br />

1,803 male and 1,946 female glass<br />

workers employed <strong>for</strong> at least 3 mos at<br />

one <strong>of</strong> 2 Finnish glass factories in 1953-<br />

1971 or 1941-1977.<br />

Cancer incidence was compared with<br />

age-, gender-, and calendar-yr-specific<br />

national rates.<br />

Stomach, lung, and skin cancer rates also<br />

were compared separately <strong>for</strong> 201 male<br />

and 34 female glassblowers and nonglassblowers.<br />

Case-control design.<br />

Cases: 344 primary liver cancer deaths<br />

reported to the Finnish Cancer Registry<br />

in 1976-1978 or 1981.<br />

Controls: registry-reported stomach<br />

cancer (476) or myocardial infarction<br />

(385) deaths in the same hospitals,<br />

frequency matched by age and gender.<br />

No specific Pb exposure indices<br />

were computed. Analyses did<br />

examine glass workers as a<br />

whole and then glassblowers<br />

specifically, which comprised<br />

the group at highest risk <strong>for</strong> Pb<br />

exposure.<br />

Questionnaires regarding job<br />

history and personal habits were<br />

sent to the closest available<br />

relative.<br />

U.K. based job-exposure matrix<br />

was used to rate potential<br />

exposure to 50 substances,<br />

including Pb compounds<br />

Industrial hygienists also<br />

inspected histories to identify<br />

those with highly probable<br />

exposure and rate it as high,<br />

low, or moderate (


AX6-199<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and<br />

Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Wesseling et al.<br />

(2002)<br />

Finland<br />

1971-1995<br />

Pesch et al. (2000)<br />

Germany<br />

1991-1995<br />

Cohort design, but at ecologic level.<br />

413,877 Finnish women with occupation<br />

reported in 1970 linked to Finnish Cancer<br />

Registry to identify new cases <strong>of</strong> brain or<br />

nervous system cancer arising <strong>for</strong>m<br />

1971 to 1995.<br />

Poisson regression was used to calculate SIRs<br />

<strong>for</strong> exposed vs. unexposed groups.<br />

Case-control design.<br />

Cases: 935 renal-cell cancer patients in five<br />

German areas.<br />

Controls: 4,298 region, age, and gendermatched<br />

controls from the surrounding<br />

population.<br />

ORs were adjusted <strong>for</strong> age, center,<br />

and smoking.<br />

Reported occupation in 1970 was<br />

used to classify women into job<br />

titles. Potential exposure <strong>for</strong><br />

each job title was estimated<br />

using a job matrix after<br />

excluding women in the highest<br />

social classes or in farming. Pb<br />

and 23 other workplace agents<br />

examined. Rates <strong>for</strong> each job<br />

title were calculated, and SIRs<br />

<strong>for</strong> low and medium/high<br />

exposure calculated (avg<br />

estimated blood Pb <strong>of</strong><br />

0.3 µmol/L served as cut point<br />

between low and medium/high<br />

exposure).<br />

Job histories were used to<br />

categorize exposure to cadmium,<br />

Pb, and other potential as low vs.<br />

medium, high, or substantial.<br />

Separate exposure estimates<br />

were obtained from British and<br />

from German-derived jobexposure<br />

matrices.<br />

SIR (95% CI), unadjusted <strong>for</strong> other metals<br />

Low exposure: 1.25 (0.68, 1.81)<br />

Medium/high exposure: 1.33 (0.90, 1.96)<br />

SIR (95% CI), adjusted <strong>for</strong> cadmium and nickel exposure<br />

Low exposure: 1.18 (0.88, 1.59)<br />

Medium/high exposure: 1.24 (0.77, 1.98)<br />

All results were adjusted <strong>for</strong> birth cohort, period <strong>of</strong> diagnosis, and<br />

job turnover rate.<br />

Incidence, exposure to Pb, and potential confounding factors were<br />

calculated at the level <strong>of</strong> job title rather than at the individual<br />

level. Exposure and other estimates were based on data <strong>for</strong> all<br />

workers pooled, not <strong>for</strong> women specifically. Job classification<br />

was based on a single yr, not lifetime job history.<br />

OR (95% CI); number <strong>of</strong> cases<br />

Substantial Pb exposure based on British matrix:<br />

Male 1.5 (1.0, 2.3); 29<br />

Female 2.6 (1.2, 5.5); 11<br />

Substantial Pb exposure based on British matrix:<br />

Male 1.3 (0.9, 2.0); 30<br />

Female not reported<br />

Analyses controlled <strong>for</strong> smoking. No control <strong>for</strong> exposure to<br />

other occupational agents.


AX6-200<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period<br />

Europe (cont’d)<br />

Study Description Pb Measurement Findings and Interpretation<br />

Kandiloris et al. (1997)<br />

Greece<br />

Cordioli et al. (1987)<br />

Italy<br />

1953-1967<br />

Cocco et al. (1994a)<br />

(expansion <strong>of</strong> Carta<br />

et al., 1994).<br />

Sardinia<br />

1931-1992<br />

Case-control design.<br />

Cases: 26 patients with histologically<br />

confirmed laryngeal carcinoma and no<br />

history <strong>of</strong> Pb exposure or toxicity.<br />

Controls: 53 patients with similar<br />

demographic pr<strong>of</strong>iles and no history <strong>of</strong><br />

cancer from the same hospital.<br />

Cohort design.<br />

468 Italian glass workers employed <strong>for</strong><br />

at least one yr between 1953 and 1967.<br />

Mortality among workers was tracked<br />

and cause <strong>of</strong> death was determined <strong>for</strong><br />

deceased workers. Standardized<br />

mortality ratios were computed <strong>for</strong><br />

workers vs. national population<br />

counterparts.<br />

Cohort design.<br />

1,741 male Sardinian Pb and zinc miners<br />

from two mines employed at least one yr<br />

between 1931 and 1971.<br />

Mortality traced through 1992 to<br />

determine cause <strong>of</strong> death.<br />

Mortality among miners was compared<br />

with age- and calendar-yr-specific<br />

regional rates to compute an SMR.<br />

Blood Pb levels and ALAD activity were<br />

measured.<br />

Workers producing low-quality glass<br />

containers were classified as Pb-exposed.<br />

All miners were considered to be exposed<br />

to Pb.<br />

Blood Pb levels were similar, but ALAD activity was<br />

significantly lower in cases than controls (Mean 50.79 U/L<br />

vs. 59.76 U/L, p < 0.01). No control <strong>for</strong> other risk factors.<br />

Potential distortion by effects <strong>of</strong> disease on Pb and/or<br />

ALAD parameters.)<br />

SMR (95% CI); number <strong>of</strong> deaths<br />

All cancer 1.3 (0.8, 1.8); 28<br />

Lung 2.1 (1.1, 3.6); 13<br />

Laryngeal 4.5 (1.2, 11.4); 4<br />

SMR (95% CI); number <strong>of</strong> deaths<br />

All cancer 0.94 (0.83, 1.05); 293<br />

Prostate 1.21; 16<br />

Bladder 1.15; 17<br />

Kidney 1.28; 7<br />

Nervous system 1.17; 8<br />

Oral 0.61; 8<br />

Lymphohemopoietic 0.91; 21<br />

Digestive 0.83; 86<br />

Peritoneum 3.67 (1.35, 7.98); 6<br />

No other p < 0.05.<br />

No control <strong>for</strong> smoking or exposure to silica, radon, or<br />

other exposures.


AX6-201<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Cocco et al. (1994b)<br />

Sardinia<br />

1951-1988<br />

Cocco et al. (1996)<br />

Sardinia<br />

1973-1992<br />

Cohort design.<br />

526 female Sardinian Pb and<br />

zinc miners from the same<br />

mines as in Cocco et al.<br />

(1994a).<br />

Mortality traced through 1992<br />

to determine cause <strong>of</strong> death.<br />

Mortality among miners was<br />

compared with age- and<br />

calendar-yr-specific regional<br />

rates to compute an SMR.<br />

Cohort design.<br />

1,222 male Sardinian Pb and<br />

zinc smelter workers whose<br />

G6PD phenotypes had been<br />

determined, employed any<br />

time from 1973-1990.<br />

Mortality traced through 1992<br />

to determine cause <strong>of</strong> death.<br />

Mortality was compared with<br />

regional rates.<br />

All miners were considered to be<br />

exposed to Pb.<br />

All workers were considered to be<br />

exposed to Pb.<br />

Workers were subdivided into<br />

6PD-normal and -deficient groups.<br />

SMR (95% CI)<br />

Liver 5.02 (1.62, 11.70)<br />

Lung 2.32 (0.85, 5.05)<br />

Other cancers showed nonsignificantly reduced rates.<br />

No control <strong>for</strong> smoking or exposure to silica, radon, or other exposures.<br />

Low statistical power due to small population and paucity <strong>of</strong> cancers<br />

during follow-up.<br />

All cancer and lung cancer: mortality lower than expected<br />

Stomach cancer: mortality higher than expected<br />

G6PD deficiency had little apparent effect on mortality: cancer and allcause<br />

mortality was slightly lower among G6PD-deficient workers than<br />

among G6PD-normal workers.<br />

No control <strong>for</strong> smoking or exposure to other agents in the smelter.<br />

Healthy worker bias-evident (all-cause mortality 31 observed vs. 44<br />

expected), brief follow-up, low proportion <strong>of</strong> older ages (mean age at<br />

entry 30, avg follow-up less than 11 yrs), no cumulative exposure data.


AX6-202<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Cocco et al. (1997)<br />

Sardinia<br />

1931-1992<br />

Wingren and Axelson<br />

(1987, 1993)<br />

(update <strong>of</strong> Wingren<br />

and Axelson, 1985,<br />

same basic cohort as in<br />

Wingren and<br />

Englander (1990)<br />

Sweden<br />

1950-1982<br />

Cohort design.<br />

1,388 male production and maintenance<br />

workers employed <strong>for</strong> at least 1 yr at a<br />

Sardinian Pb and zinc smelter between<br />

June <strong>of</strong> 1932 and July <strong>of</strong> 1971.<br />

Mortality was followed up through 1992.<br />

Mortality was compared with age- and<br />

calendar-yr-specific regional rates.<br />

Since regional rates were only available<br />

<strong>for</strong> 1965 and later, analyses were limited<br />

to this period.<br />

Case-control design.<br />

Source population: 5,498 men aged<br />

45 or older in 11 Swedish parishes,<br />

including 887 glass workers.<br />

Cancer-specific nested case-control<br />

analysis:<br />

Cases: deaths due to stomach, colon,<br />

and lung cancer from 1950-1982<br />

Controls: deaths due to causes other<br />

than cancer or cardiovascular disease<br />

All workers were considered to<br />

be exposed to Pb.<br />

Glass workers were considered<br />

exposed.<br />

Glassblowers also singled out<br />

as workers with higher<br />

exposure potential.<br />

Job history applied to job<br />

matrix to categorize<br />

occupations as low, moderate,<br />

or high Pb exposure.<br />

SMRs vs. regional rates (95% CI); number <strong>of</strong> deaths<br />

Lung 0.82 (0.56, 1.16); 31<br />

Stomach 0.97 (0.53, 1.62); 14<br />

All cancers 0.93 (0.78, 1.10); 132<br />

Kidney 1.75 (0.48, 4.49); 4<br />

Bladder 1.45 (0.75, 2.53); 12<br />

Brain 2.17 (0.57, 5.57); 4<br />

Kidney cancer showed a significant trend toward increasing risk with<br />

increasing duration <strong>of</strong> exposure<br />

No significant trends were noted <strong>for</strong> lung or other cancers<br />

Brain cancer excess was limited to workers employed <strong>for</strong> 10 yrs or<br />

less.<br />

No control <strong>for</strong> smoking or exposure to arsenic or other smelterrelated<br />

exposures. No data on intensity <strong>of</strong> exposure.<br />

Strong association <strong>of</strong> smelter work with pneumoconiosis and other<br />

respiratory disease (SMR = 4.47, 95% CI: 3.37, 5.80); since this<br />

outcome includes silicosis, which is thought to predispose individuals<br />

to lung cancer, some lung cancer deaths may have been missed due to<br />

misclassification <strong>of</strong> cause <strong>of</strong> death based on death certificates.<br />

OR (90% CI); number <strong>of</strong> deaths<br />

All glass workers:<br />

Lung 1.7 (1.1, 2.5); 86<br />

Stomach 1.5 (1.1, 2.0); 206<br />

Colon 1.6 (1.0, 2.5); 79<br />

Glassblowers:<br />

Lung 2.3<br />

Stomach 2.6<br />

Colon 3.1<br />

Glassblowers singled out from glass workers as a whole thus showed<br />

higher estimated risk. ORs <strong>for</strong> high or moderate vs. low exposure<br />

showed no consistent increase <strong>for</strong> lung or stomach cancer, however,<br />

although they did show mild upward trend <strong>for</strong> colon cancer.<br />

No control <strong>for</strong> smoking or other occupational exposures.


AX6-203<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Wingren and<br />

Englander (1990)<br />

Sweden<br />

1964-1985<br />

(same population as in<br />

case-control analyses<br />

<strong>of</strong> Wingren and<br />

Axelson 1985, 1987,<br />

1993)<br />

Dingwall-Fordyce<br />

and Lane (1963)<br />

U.K.<br />

1925-1962<br />

Malcolm and Barnett<br />

(1982) (follow-up <strong>of</strong><br />

Dingwall-Fordyce and<br />

Lane, 1963)<br />

U.K.<br />

1925-1976<br />

Cohort design.<br />

625 Swedish glass workers employed<br />

<strong>for</strong> at least 1 mo between 1964<br />

and 1985.<br />

Mortality was compared with national<br />

rates.<br />

Cohort design.<br />

425 male employees drawing pensions<br />

from U.K. battery plants.<br />

Standardized mortality <strong>for</strong> employees<br />

vs. national population counterparts.<br />

Cohort design.<br />

1,898 Pb-acid battery workers.<br />

Mortality was traced <strong>for</strong> the Pb-acid<br />

battery workers to determine cause <strong>of</strong><br />

death. The proportion <strong>of</strong> deaths due to<br />

cancer (all types and major<br />

subcategories) among the worker<br />

population was compared to that seen in<br />

corresponding members <strong>of</strong> the general<br />

population, yielding a PMR.<br />

Workers from areas with<br />

airborne Pb levels up to 0.110<br />

mg/m 3 were classified as<br />

exposed.<br />

Battery plant workers were<br />

assumed to be exposed, and<br />

their mortality compared to that<br />

<strong>of</strong> like age and gender in the<br />

U.K. population as a whole.<br />

Urinary Pb excretion was also<br />

used to categorize workers by<br />

estimated exposure (none, light,<br />

or heavy): 80 lightly and 187<br />

heavily (at least 100 µg/L)<br />

exposed.<br />

Job histories were reviewed to<br />

classify workers’ Pb exposure<br />

as high, medium, or none.<br />

SMR (95% CI)<br />

Pharyngeal: 9.9 (1.2, 36.1)<br />

Lung: 1.4 (0.5, 3.1)<br />

Colon: nonsignificant<br />

SMR (95% CI); number observed deaths<br />

All cancer: 1.2 (0.8, 1.7); 267<br />

No consistent increase in SMRs across categories <strong>of</strong> increasing Pb<br />

exposure.<br />

Limitations: No cancer site-specific analyses. No control <strong>for</strong><br />

potential confounders including smoking and exposure to arsenic or<br />

other metals.<br />

Proportionate mortality ratio (PMR)<br />

All cancers:<br />

1.15 (136 deaths), p > 0.05<br />

By exposure:<br />

None 1.02<br />

Medium 1.06<br />

High 1.30<br />

No significant excesses <strong>for</strong> individual cancer sites except <strong>for</strong><br />

digestive cancer PMR <strong>of</strong> 1.67, p < 0.01, among nonexposed workers.<br />

The difference in exposure <strong>for</strong> the high and medium exposure groups<br />

narrowed greatly over the follow-up, thus complicating interpretation<br />

<strong>of</strong> dose-response patterns. No control <strong>for</strong> smoking or occupational<br />

exposure to other carcinogens.


AX6-204<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Europe (cont’d)<br />

Ades and Kazantzis<br />

(1988)<br />

U.K.<br />

1943-1982<br />

Asia<br />

Hu et al. (1998)<br />

China<br />

1989-1996<br />

Cohort design.<br />

4,393 male zinc, Pb, and cadmium smelter<br />

workers.<br />

(Workers born after 1939 or who had worked<br />

less than one yr at the facility were excluded.)<br />

Workers followed up <strong>for</strong> mortality.<br />

Nested case-control analysis also conducted to<br />

quantitatively assessed cadmium and,<br />

secondarily, arsenic, Pb, and other metal<br />

exposures among 174 cases.<br />

Case-control design.<br />

Cases: 218 patients with histologicallyconfirmed<br />

primary gliomas occurring during<br />

1989-1996 at 6 Chinese hospitals.<br />

Controls: 436 patients with non-neurological,<br />

nonmalignant disease, matched by age, gender,<br />

and residence from the same hospitals<br />

(excluding one cancer-only center).<br />

Job histories were used to quantify<br />

cadmium exposure and assign<br />

ordinal ranks <strong>for</strong> exposure to Pb and<br />

other metals.<br />

Standardized lung cancer mortality<br />

ratio computed <strong>for</strong> workers vs.<br />

national rates.<br />

Patients were interviewed, and those<br />

with factory or farm occupations<br />

were further interviewed to identify<br />

exposure to Pb (or other potentially<br />

toxic substances).<br />

SMR (95% CI); number <strong>of</strong> deaths<br />

Cohort:<br />

Lung 1.25 (1.07, 1.44); 174<br />

Increased significantly with duration <strong>of</strong> employment.<br />

Nested case-control analyses did not implicate any<br />

department or process, nor did cadmium, zinc, sulfur dioxide,<br />

or dust exposure account <strong>for</strong> the observed increase.<br />

Cumulative exposure to Pb and to arsenic both showed<br />

positive associations with lung cancer, but the relative<br />

importance <strong>of</strong> these two exposures could not be determined.<br />

Cadmium exposure did not account <strong>for</strong> the elevated SMR,<br />

but analyses could not control <strong>for</strong> exposure, and were not<br />

adjusted <strong>for</strong> smoking.<br />

Occupational exposure to Pb:<br />

Not reported <strong>for</strong> any glioma patients, but was reported <strong>for</strong><br />

4 controls.<br />

No control <strong>for</strong> exposure to other occupational or<br />

environmental agents.


AX6-205<br />

Table AX6-7.4 (cont’d). Other Studies <strong>of</strong> <strong>Lead</strong> Exposure and Cancer<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings and Interpretation<br />

Asia (cont’d)<br />

Hu et al. (1999)<br />

China<br />

1989-1996<br />

Shukla et al. (1998)<br />

India<br />

1995-1996<br />

Case-control design.<br />

Cases: 383 patients with histologically<br />

confirmed primary meningiomas<br />

occurring during 1989-1996 at 6 Chinese<br />

hospitals.<br />

Controls: 366 patients with nonneurological,<br />

nonmalignant disease<br />

matched by age, gender, and residence<br />

from the same hospitals (excluding one<br />

cancer-only center).<br />

Case-control design.<br />

Cases: 38 patients with newly<br />

diagnosed, histologically confirmed gall<br />

bladder cancer cases assembled from a<br />

surgical unit.<br />

Controls: 58 patients with gall stones<br />

diagnosed at the same surgical unit,<br />

matched on geographic area.<br />

Mean bile Pb content was compared<br />

between cases and controls.<br />

Patients were interviewed, and<br />

those with factory or farm<br />

occupations were further<br />

interviewed to identify<br />

exposure to Pb (or other<br />

potentially toxic substances).<br />

Heavy metal content was<br />

measured in bile drawn from<br />

the gall bladder at time <strong>of</strong><br />

surgery.<br />

OR (95% CI); number <strong>of</strong> cases<br />

Occupational exposure to Pb:<br />

Male: 7.20 (1.00, 51.72); 6<br />

Female: 5.69 (1.39, 23.39); 10<br />

Results were adjusted <strong>for</strong> income, education, and fruit and vegetable<br />

intake, plus cigarette pack-yrs <strong>for</strong> the women. No control <strong>for</strong><br />

exposure to additional metals or other occupational exposures.<br />

Bile Pb content: mean (SE)<br />

Gall bladder cancer: 58.38 mg/L (1.76)<br />

Gallstones: 3.99 mg/L (0.43)<br />

Cadmium and chromium levels also were elevated in cancer patients,<br />

but less than Pb. No control <strong>for</strong> smoking or any other risk factors.


ANNEX TABLES AX6-8<br />

AX6-206


AX6-207<br />

Table AX6-8.1. Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Joseph et al. (2005)<br />

SE Michigan<br />

(1994-1998)<br />

Sarasua et al. (2000)<br />

ATSDR Multi-site<br />

Study: Granite City,<br />

IL, Galena, KA; Joplin,<br />

MO; Palmerton, PA<br />

1991<br />

Rabinowtiz et al. (1990)<br />

Boston, MA<br />

1979–1987<br />

Design: prospective (1 yr following 3-yr<br />

baseline recruitment)<br />

Subjects: children (n = 4634), age range<br />

0.4–3.0 yr<br />

Outcome measures: asthma prevalence and<br />

incidence.<br />

Analysis: multivariate proportional hazard<br />

model (Cox)<br />

Design: cross-sectional<br />

Subjects: children and adults (n = 2036)<br />

Outcome measures: total lymphocyte count,<br />

lymphocyte phenotype abundance, serum<br />

IgA, IgG, and IgM.<br />

Analysis: multivariate linear regression<br />

Design: cross-sectional<br />

Subjects: infants/children (n = 1768)<br />

Outcome measures: incidence <strong>of</strong> illness in<br />

children was solicited from parents by<br />

questionnaire.<br />

Analysis: relative risk <strong>of</strong> illness estimated<br />

from incidence ratios, highest: combined<br />

lower blood Pb deciles, without adjustment<br />

<strong>for</strong> covariates or confounders.<br />

Blood Pb (µg/dL) mean<br />

(SD, median, % >10):<br />

5.5 (4.0, 4.0, 8.6%)<br />

Blood Pb (µg/dL) mean<br />

(SD, 5th–95th %):<br />

6–35 mo: 7.0<br />

(16, 1.1–16.1)<br />

36–71 mo: 6.0<br />

(4.3, 1.6–14.1)<br />

6–15 yr: 4.0<br />

(2.8,1.1–9.2)<br />

16–75 yr: 4.3<br />

(2.9, 1.0–9.9)<br />

Cord blood Pb (µg/dL)<br />

~90th %: 10<br />

Shed tooth Pb (µg/g) ~90th<br />

%: 5<br />

Covariate-adjusted hazards ratio (HR, asthma incidence


AX6-208<br />

Table AX6-8.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Lutz et al. (1999)<br />

Springfield-Green Co,<br />

MO<br />

NR<br />

Europe<br />

Annesi-Maesano et al.<br />

(2003)<br />

France<br />

1985, 1992<br />

Karmaus et al. (2005)<br />

Germany<br />

1994–1997<br />

Design: cross-sectional<br />

Subjects: children (n = 279; age range 9<br />

mo–6 yr)<br />

Outcome measures: differential blood cell<br />

counts; lymphocyte phenotype abundance<br />

(%); and serum IL-4, soluble CD25, CD27,<br />

IgE and IgG (Rubella).<br />

Analysis: nonparametric comparison <strong>of</strong><br />

outcome measures (adjusted <strong>for</strong> age) <strong>for</strong><br />

blood Pb categories, correlation<br />

Design: cross-sectional<br />

Subjects: mother/newborn pairs (n = 374),<br />

mean age 30 yr<br />

Outcome measures: maternal venous and<br />

newborn cord serum IgE levels<br />

Analysis: multivariate linear regression,<br />

ANOVA<br />

Design: cross-sectional<br />

Subjects: children (n = 331, 57% male), age<br />

7–8 yrs (96%), 9–10 yrs (4%)<br />

Outcome measures: differential blood cell<br />

count; lymphocyte phenotype abundance;<br />

and serum IgA, IgE, IgG, IgM<br />

Analysis: multivariate linear regression<br />

Blood Pb (µg/dL) range:<br />

1–45<br />

Blood Pb categories:<br />


AX6-209<br />

Table AX6-8.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Reigart and Graber<br />

(1976)<br />

NR<br />

NR<br />

Wagnerova et al. (1986)<br />

Czech<br />

NR<br />

Latin America<br />

Pineda-Zavaleta et al.<br />

(2004)<br />

Mexico<br />

NR<br />

Design: clinical<br />

Subjects: children (n = 19), ages 4–6 yrs<br />

Outcome measures: serum IgA, IgG, IgM,<br />

total complement and C-3, be<strong>for</strong>e and after<br />

immunization with tetanus toxoid<br />

Analysis: none; presentation <strong>of</strong> prevalence<br />

<strong>of</strong> clinically low, normal, and high values <strong>of</strong><br />

outcome measures<br />

Design: longitudinal cohort (repeated<br />

measures <strong>for</strong> 2-yrs)<br />

Subjects: children (n = 92, 38 females) ages<br />

11–13 yrs residing near a smelter; reference<br />

group (n = 67, 36 females), ages 11–13 yrs<br />

Outcome measures: serum IgA, IgE, IgG,<br />

IgM<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

and between exposed and reference groups,<br />

stratified sex and season <strong>of</strong> sampling<br />

Design: cross-sectional<br />

Subjects: children (n = 30 female, 35 male)<br />

ages 6–11 yrs, residing near smelter<br />

Outcome measures: mitogen- (PHA) and<br />

cytokine- (IFN-() induced nitric oxide and<br />

superoxide production in lymphocytes<br />

Analysis: multivariate linear regression<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

High: >40 (n = 12): 45.3<br />

(41–51)<br />

Low: #30 (n = 7): 22.6<br />

(14–30)<br />

Blood Pb (µg/dL) mean:<br />

Pb: ~23–42<br />

Reference: ~5–22<br />

Blood Pb (µg/dL) mean<br />

(range) <strong>for</strong> 3 schools:<br />

1 (n = 21): 7.0 (3.5–25.3)<br />

2 (n = 21): 20.6<br />

(10.8–49.2)<br />

3 (n = 23): 30.4<br />

(10.3–47.5)<br />

No apparent difference in prevalence <strong>of</strong> abnormal values <strong>for</strong> serum<br />

immunoglobulin or complement (no statistical analysis applied).<br />

Significant (p NR, statistic NR) lower serum IgE and IgM levels in<br />

exposed group compared to reference group.<br />

Significant (p = 0.036) association between increasing blood Pb<br />

concentration and covariate adjusted decreasing nitric oxide<br />

production in PHA-activated lymphocytes (∃ = −0.00089 [95% CI:<br />

−0.0017, −0.00005]).<br />

Significant (p = 0.034) association between increasing blood Pb<br />

concentration and covariate adjusted increasing super oxide<br />

production in IFN-(-activated lymphocytes (∃ = −0.00389 [95% CI:<br />

0.00031, 0.00748]). Covariates considered included age, sex,<br />

allergies, and blood arsenic (age, sex, and blood arsenic were<br />

retained).<br />

Significant effect <strong>of</strong> sex on associations, significant blood Pb-arsenic<br />

interaction.<br />

Covariates considered included age, sex, allergies, urinary arsenic<br />

(age, sex, and urinary arsenic were retained).


AX6-210<br />

Table AX6-8.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia<br />

Sun et al. (2003); Zhao<br />

et al. (2004)<br />

China<br />

NR<br />

Design: cross-sectional<br />

Subjects: children (n = 73) age 3–6 yrs<br />

Outcome measures: serum IgE, IgG, IgM;<br />

lymphocyte phenotype abundance<br />

Analysis: Nonparametric comparisons <strong>of</strong><br />

outcome measures stratified by blood Pb<br />

Blood Pb (µg/dL) mean<br />

(SD, range) (n = 217):<br />

9.5 (5.6, 2.6–43.7)<br />

Females: significantly higher (p < 0.05) IgE levels in high blood Pb<br />

category (∃10 µg/dL, n = 16) compared to low category (


AX6-211<br />

Table AX6-8.2. Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Pinkerton et al. (1998)<br />

U.S.<br />

NR<br />

Sarasua et al. (2000)<br />

ATSDR Multi-site<br />

Study: Granite City,<br />

IL, Galena, KA; Joplin,<br />

MO; Palmerton, PA<br />

1991<br />

Design: cross-sectional cohort<br />

Subjects: adult male smelter workers<br />

(n = 145, mean age 32.9∀8.6); reference<br />

group, male hardware workers (n = 84, mean<br />

age 30.1∀9.3)<br />

Outcome measures: differential blood cell<br />

counts; lymphocyte phenotype abundance;<br />

serum IgA, IgG, IgM; salivary IgA;<br />

lymphocyte proliferation (tetanus toxoid)<br />

Analysis: multivariate logistic regression<br />

with comparison <strong>of</strong> adjusted outcome<br />

measures between exposed and nonexposed<br />

groups<br />

Design: cross-sectional cohort<br />

Subjects: children and adults (n = 2036)<br />

Outcome measures: total lymphocyte count,<br />

lymphocyte phenotype abundance, serum<br />

IgA, IgG, and IgM<br />

Analysis: multivariate linear regression<br />

Blood Pb (µg/dL) median<br />

(range)<br />

Pb: 39 (15–55)<br />

Reference:


AX6-212<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Fischbein et al. (1993)<br />

New York<br />

NR<br />

Europe<br />

Bergeret et al. (1990)<br />

France<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult firearms instructors (n = 51),<br />

mean age 48 yr; age-matched reference<br />

subjects (n = 36).<br />

Outcome measures: lymphocyte phenotype<br />

abundance, lymphocyte proliferation (PHA,<br />

PWM, Staph. aureus)<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between reference and blood Pb categories;<br />

multivariate linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult battery smelting workers<br />

(n = 34), mean age 40 yr; reference subjects<br />

(n = 34), matched <strong>for</strong> age, sex, ethnic origin,<br />

smoking and alcohol consumption habits,<br />

intake <strong>of</strong> antibiotics, and NSAIDs<br />

Outcome measures: PMN chemotaxis<br />

(FMLP); PMN phagocytosis (opsonized<br />

zymosan)<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between worker and reference groups<br />

Blood Pb (µg/dL) mean<br />

(SD)<br />

Pb high (∃25): 31.4 (4.3)<br />

Pb low (


AX6-213<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Ewers et al. (1982)<br />

Germany<br />

NR<br />

Coscia et al. (1987)<br />

Italy<br />

NR<br />

Governa et al. (1987)<br />

Italy<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture or<br />

smelter workers (n = 72), mean age 36.4 yr<br />

(16–58); reference workers (n = 53), mean<br />

age 34.8 yr (21–54)<br />

Outcome measures: serum IgA, IgG, IgM,<br />

C3; saliva IgA<br />

Analysis: parametric and nonparametric<br />

comparison <strong>of</strong> outcome measures between<br />

Pb workers and reference subjects; linear<br />

regression<br />

Design: cross-sectional cohort<br />

Subjects: adult Pb workers (n = 32, 2<br />

female), mean age 42.8 yr (SD 11.5);<br />

reference subjects (n = 25), mean age 38.6 yr<br />

(SD 13.3)<br />

Outcome measures: serum IgA, IgG, IgM,<br />

C3-C4; lymphocyte phenotype abundance<br />

Analysis: parametric comparison <strong>of</strong><br />

outcome measures between worker and<br />

reference groups<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 9), mean age 38.4 yr (SD 13.7);<br />

age-matched reference subjects (n = 18)<br />

Outcome measures: PMN chemotaxis<br />

(zymosan-activated serum)<br />

Analysis: parametric comparison <strong>of</strong><br />

outcome measures between worker and<br />

reference groups, correlation<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Pb: 55.4.0 (18.6–85.2)<br />

Reference: 12.0 (6.6–20.8)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 62.3 (21.6)<br />

Reference: NR<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 63.2 (8.2)<br />

Reference: 19.2 (6.4)<br />

Significantly (p < 0.05) lower serum IgM, lower salivary IgA in Pb<br />

workers compared to reference group.<br />

Outcomes in Pb workers that were significantly (p < 0.05) different<br />

from reference group ([+], higher, [−] lower): [−] serum IgM, [+]<br />

serum C4, [+] lymphocyte abundance (%), [−] T-cell abundance (%,<br />

number, E-rosette <strong>for</strong>ming cells), [+] B-cell abundance (%,number,<br />

immunoglobulin-bearing cells), [+] CD8 + cell abundance (number).<br />

Significantly (p < 0.05) lower PMN chemotactic response to<br />

zymosan activated serum. Effect magnitude was not correlated with<br />

blood Pb.


AX6-214<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Valentino et al. (1991)<br />

Italy<br />

NR<br />

Kimber et al. (1986)<br />

UK<br />

NR<br />

Latin America<br />

Queiroz et al. (1993)<br />

Brazil<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb scrap refining<br />

workers (n = 10), mean age 41.1 yr (SD 7.3,<br />

range 28–54); age-matched reference<br />

subjects (n = 10)<br />

Outcome measures: PMN chemotaxis (C5 or<br />

FMLP) and phagocytosis (FMLP)<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between worker and reference groups,<br />

correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult male TEL manufacture<br />

workers (n = 39) mean age: 45.1 yr; and<br />

age-matched reference subjects (n = 21);<br />

mean age 32.2 yr<br />

Outcome measures: serum IgA, IgG, IgM;<br />

mitogen (PHA)-induced<br />

lymphoblastogenesis; and NK cell<br />

cytotoxicity<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

<strong>for</strong> exposed and reference groups<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 39), mean age 33.9 yr (SD 12.1,<br />

range 18–56); reference subjects (n = 39)<br />

matched by age and race<br />

Outcome measures: PMN chemotaxis<br />

(endotoxin LPS); phagocytic (endotoxin<br />

LPS) respiratory burst activity (NBT<br />

reduction)<br />

Analysis: nonparametric comparison <strong>of</strong><br />

outcome measures between worker and<br />

reference groups<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 33.2 (5.6, 25–42)<br />

Reference: 12.6 (2.5, 8.9–<br />

18)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 38.4 (5.6, 25–53)<br />

Reference: 11.8 (2.2, 8–<br />

17)<br />

Blood Pb (µg/dL) range:<br />

Pb: 14.8–91.4 (>30,<br />

n = 52)<br />

Reference:


AX6-215<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America (cont’d)<br />

Queiroz et al. (1994a)<br />

Brazil<br />

NR<br />

Queiroz et al. (1994b)<br />

Brazil<br />

NR<br />

Asia<br />

Kuo et al. (2001)<br />

China<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 60), mean age 33.9 yr (range<br />

18–56); reference subjects (n = 49) matched<br />

by age and race<br />

Outcome measures: PMN phagocytic/lytic<br />

activity (opsonized yeast)<br />

Analysis: nonparametric comparison <strong>of</strong><br />

outcome measures between worker and<br />

reference groups<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 33), mean age 32.4 yr (range<br />

18–56); reference subjects (n = 20) matched<br />

by age and race<br />

Outcome measures: serum IgA, IgG, IgM;<br />

mitogen (PHA)-induced lymphocyte<br />

proliferation<br />

Analysis: parametric comparison <strong>of</strong><br />

outcome measures between worker and<br />

reference groups<br />

Design: cross-sectional cohort<br />

Subjects: adult battery manufacture workers<br />

(n = 64, 21 female) 14 subject aged 50 yr; nonexposed<br />

reference subjects (n = 34, 17 female).<br />

Outcome measures: differential blood cell<br />

counts, lymphocyte phenotype abundance<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

in exposed and reference groups,<br />

multivariate linear regression<br />

Blood Pb (µg/dL) range:<br />

Pb: 14.8–91.4 (>30,<br />

n = 27)<br />

Reference: 30,<br />

n = 27)<br />

Reference:


AX6-216<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Mishra et al. (2003)<br />

India<br />

NR<br />

Alomran and<br />

Shleamoon (1988)<br />

Iraq<br />

NR<br />

Cohen et al. (1989)<br />

Israel<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult males occupationally<br />

exposed to Pb (n = 84), mean age 30 yr;<br />

reference subjects (n = 30), mean age 29 yr<br />

Outcome measures: serum IFN-( level,<br />

mitogen (PHA)-induced lymphocyte<br />

proliferation, NK cell cytotoxicity<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb-exposed and reference groups,<br />

correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult Pb (oxide) workers (n = 39),<br />

mean age 35.6 yr (9,2, SD); age-matched<br />

reference subjects (n = 19)<br />

Outcome measures: serum IgA, IgG;<br />

mitogen (PHA, Con-A)-induced lymphocyte<br />

proliferation<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

Design: cross-sectional cohort<br />

Subjects: adult male occupationally Pb<br />

exposed (n = 10), age range 22–70; agematched<br />

reference subjects (n = 10)<br />

Outcome measures: mitogen (Con A, PHA)induced-lymphocyte<br />

proliferation and Tsuppressor<br />

cell proliferation; lymphocyte<br />

phenotype abundance<br />

Analysis: parametric comparison <strong>of</strong><br />

outcome means between Pb-exposed and<br />

reference groups<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

3-wheel drivers (n = 30):<br />

6.5 (4.7, 0.0–17.5)<br />

Battery workers (n = 34):<br />

128.1 (13.2–400.8)<br />

Jewelry makers: 17.8<br />

(18.5, 3.1–76.8)<br />

Reference: 4.5 (NR, 1.6–<br />

9.8)<br />

Blood Pb (µg/dL) mean:<br />

Pb: 54–64<br />

Reference: NR<br />

Blood Pb (µg/dL) range:<br />

Exposed: 40–51<br />

Reference:


AX6-217<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Sata et al. (1998)<br />

Japan<br />

NR<br />

Sata et al. (1997)<br />

Japan<br />

NR<br />

Heo et al. (2004)<br />

Korea<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb stearate manufacture<br />

workers (n = 71), mean age 48 yr (range 24–<br />

74); reference subjects (n = 28), mean age 55<br />

yr (range 33–67).<br />

Outcome measures: lymphocyte phenotype<br />

abundance<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

in exposed and reference groups<br />

(ANCOVA), multivariate linear regression<br />

Design: clinical<br />

Subjects: adult male Pb smelter workers<br />

(n = 2) who underwent CaEDTA therapy<br />

Outcome measures: serum IgA, IgG, IgD,<br />

IgM; lymphocyte phenotype abundance<br />

Analysis: Parametric comparison <strong>of</strong><br />

outcome measures be<strong>for</strong>e and after<br />

treatment, correlation <strong>of</strong> outcome means with<br />

blood Pb<br />

Design: cross-sectional cohort<br />

Subjects: adults, battery manufacture<br />

workers (n = 606; 52 females); ages: 40 yr, n = 123.<br />

Outcome measures: serum IgE, IL-4, IFN(<br />

Analysis: comparison <strong>of</strong> outcomes measures<br />

(ANOVA), stratified by age and blood Pb<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Pb: 19 (7–50)<br />

Reference: NR<br />

Blood Pb (µg/dL):<br />

Subject 1: 81 µg/dL at<br />

referral; mean be<strong>for</strong>e<br />

EDTA: 45.1 (SD 16.0);<br />

after chelation: 31.0 (9.8)<br />

Subject 2: 68 µg/dL at<br />

referral; mean be<strong>for</strong>e<br />

EDTA: 43.3 (SD 14.1);<br />

after chelation: 33.7 (7.2)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />


AX6-218<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Ünde er et al. (1996);<br />

Ba∏aran and Ünde er<br />

(2000)<br />

Turkey<br />

NR<br />

Yücesoy et al. (1997a)<br />

Turkey<br />

NR<br />

Yücesoy et al. (1997b)<br />

Turkey<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 25), mean age, 33 yr (22–55);<br />

reference subjects (n = 25) mean age 33 yr<br />

(22–56).<br />

Outcome measures: differential blood cell<br />

counts; lymphocyte phenotype abundance;<br />

serum IgA, IgG, IgM, C3, and C4; neutrophil<br />

chemotaxis (zymosan-activated serum); latex<br />

particle-induced neutrophil phagocytic (latex<br />

particles) respiratory burst (NBT reduction)<br />

Analysis: nonparametric and parametric<br />

comparisons <strong>of</strong> outcome measures <strong>for</strong><br />

exposed and reference groups<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 20), ages 39–48 yr; agematched<br />

reference subjects (n = 12)<br />

Outcome measures: serum cytokines IL-1∃,<br />

IL-2, TNF∀, IFN-(<br />

Analysis: parametric and nonparametric<br />

comparison <strong>of</strong> outcome measures in exposed<br />

and reference groups<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 50), ages 39–48 yr; agematched<br />

reference subjects (n = 10)<br />

Outcome measures: lymphocyte phenotype<br />

abundance, NK cell cytotoxicity<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

in exposed and reference groups<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 74.8 (17.8)<br />

Reference: 16.7 (5.0)<br />

Blood Pb (µg/dL) mean<br />

(SE, range):<br />

Pb: 59.4 (3.2, 42–94)<br />

Reference: 4.8 (1.0, 2–15)<br />

Blood Pb (µg/dL) mean<br />

(SE, range):<br />

Pb 1 (n = 20): 59.4 (3.2,<br />

42–94)<br />

Pb 2 (n = 30): 58.4 (2.5,<br />

26–81)<br />

Reference: 4.0 (0.4, 2–6)<br />

Workers relative to reference: significantly (p < 0.05) lower serum<br />

IgG, IgM, C3, and C4 levels; lower CD4 + (“T-helper”) abundance,<br />

lower neutrophil chemotactic response; no significant difference in<br />

CD20 + (B-cell) , CD8 + (“T-suppressor”) cell, CD56 + (NK) cell<br />

abundance, or particle-induced NK cell respiratory burst.<br />

Significantly (p < 0.05) lower serum IL-1∃ and IFN-( levels in Pb<br />

workers compared to controls.<br />

Significantly (p < 0.05) lower CD20 + B-cell (%) abundance in Pb<br />

workers compared to controls, no difference in % CD4 + T-cell<br />

abundance.


AX6-219<br />

Table AX6-8.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Immune Function in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Africa<br />

Anetor and Adeniyi<br />

(1998)<br />

Nigeria<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male “Pb workers” (n = 80),<br />

mean age, 36 yr (21–66) and reference<br />

subjects (n = 50), mean age 37 yr (22–58).<br />

Outcome measures: serum IgA, IgG, and<br />

IgM; lymphocyte count<br />

Analysis: comparison <strong>of</strong> outcomes measures<br />

in workers and reference group, linear<br />

regression, principal component analysis<br />

Blood Pb (µg/dL) mean<br />

(SE):<br />

Pb: 53.6 (0.95)<br />

Reference: 30.4 (1.4)<br />

Significantly lower (p < 0.05) serum IgA, IgG, and total blood<br />

lymphocyte levels; significant associations and interactions between<br />

blood Pb and serum total globulins (note high blood Pb levels in<br />

reference).


ANNEX TABLES AX6-9<br />

AX6-220


AX6-221<br />

Table AX6-9.1. Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Marcus and Schwartz<br />

(1987)<br />

U.S.<br />

1976–1980<br />

Piomelli et al. (1982)<br />

New York<br />

1976<br />

Soldin et al. (2003)<br />

Washington DC<br />

2001–2002<br />

Europe<br />

Roels and Lauwerys<br />

(1987)<br />

Belgium<br />

1974–1980<br />

Design: cross-sectional national survey<br />

(NHANES <strong>II</strong>)<br />

Subjects: ages 2-6 yr (n = 1677)<br />

Outcome measures: EP, red blood cell count,<br />

mean corpuscular volume, iron status variables<br />

Analysis: nonlinear least squares regression<br />

Design: cross-sectional<br />

Subjects: children (n = 2002), ages 2–12 yr<br />

Outcome measures: EP<br />

Analysis: linear regression<br />

Design: cross-sectional<br />

Subjects: children (n = 4908, 1812 females),<br />

age range 0–17 yr<br />

Outcome measures: EP<br />

Analysis: locally weighted scatter plot<br />

smoother (LOWESS)<br />

Design: cross-sectional<br />

Subjects: children (n = 143), age range<br />

10–13 yr<br />

Outcome measures: ALAD, urinary ALA, EP<br />

Analysis: linear regression, correlation<br />

Blood Pb (µg/dL) range:<br />

6-65<br />

Blood Pb (µg/dL) range:<br />

2–98<br />

Blood Pb (µg/dL):<br />

Mean (range 1–17 yr):<br />

2.2–3.3<br />

Median (1–17 yr): 3<br />

Range: 31%).<br />

Regression equation relating blood Pb concentration to EP<br />

(log-trans<strong>for</strong>med):<br />

∀ = 1.099, ∃ = 0.016, r = 0.509, p < 0.001<br />

Threshold <strong>for</strong> increase in EP estimated to be: 15.4 µg/dL (95%<br />

CI: 12.9, 18.2)<br />

EP increases as blood Pb concentration increased above<br />

15 mg/dL. A doubling <strong>of</strong> EP occurred with an increase in blood<br />

Pb concentration <strong>of</strong> ~20 µg/dL (a polynomial expression <strong>for</strong> EP as<br />

a function <strong>of</strong> blood Pb (PbB) is:<br />

EP = −0.0015(blood Pb) 3 + 0.1854(blood Pb) 2 − 2.7554(blood Pb)<br />

+ 30.911 (r 2 = 0.9986)<br />

(derived from data in Table 2 <strong>of</strong> Soldin et al. (2003)<br />

Linear regression <strong>for</strong> EP (log-trans<strong>for</strong>med) and blood Pb<br />

concentration:<br />

∀ = 1.321, ∃ = 0.025, r = 0.73 (n = 51)<br />

Linear regression <strong>for</strong> ALA (log-trans<strong>for</strong>med) and blood Pb<br />

concentration:<br />

∀ = 0.94, ∃ = 0.11, r = 0.54 (n = 37)<br />

Linear regression <strong>for</strong> ALAD (log-trans<strong>for</strong>med) and blood Pb<br />

concentration:<br />

∀ = 1.864, ∃ = −0.015, r = −0.87 (n = 143)


AX6-222<br />

Table AX6-9.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Perez-Bravo et al.<br />

(2004)<br />

Chile<br />

NR<br />

Design: cross-sectional;<br />

Subjects: children (n = 93, 43 males), aged 5-<br />

12 yrs who attended school near a powdered Pb<br />

storage facility<br />

Outcome measures: blood Hgb and Hct, ALAD<br />

genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Blood Pb (µg/dL) mean<br />

(SE):<br />

ALAD1 (n = 84):<br />

13.5 (8.7)<br />

ALAD2 (n = 9): 19.2 (9.5)<br />

Mean blood Pb, blood Hgb, and Hct not different between ALAD<br />

genotypes (p = 0.13).


AX6-223<br />

Table AX6-9.2. Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Gennart et al. (1992)<br />

Belgium<br />

NR<br />

Mohammed-Brahim<br />

et al. (1985)<br />

Belgium<br />

NR<br />

Roels and Lauwerys<br />

(1987)<br />

Belgium<br />

1974–1980<br />

Design: cross-sectional cohort<br />

Subjects: adult battery manufacture workers<br />

(n = 98), mean age, 37.7 yr (range 22–55);<br />

reference group (n = 85), mean age 38.8 yr<br />

(24–55)<br />

Outcome measures: blood Hct, blood EP,<br />

urine ALA<br />

Analysis: linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult smelter and ceramics<br />

manufacture workers (n = 38, 13 females);<br />

reference subjects (n = 100) matched with<br />

worker group by age, sex, and socioeconomic<br />

status.<br />

Outcome measures: blood P5N, EP, ALAD,<br />

R/ALAD (ratio <strong>of</strong> ALAD be<strong>for</strong>e and after<br />

reactivation).<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

(ANOVA) between Pb workers and reference<br />

group; correlation<br />

Design: cross-sectional<br />

Subjects: adults (n = 75, 36 females)<br />

Outcome measures: ALAD, urinary ALA, EP<br />

Analysis: linear regression, correlation<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 51.0 (8.0, 40–70)<br />

Reference: 20.9<br />

(11.1, 4.4–30.0)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 48.5 (9.1, 27.8–66.6)<br />

Reference: 14.3<br />

(6.7, 5.6–33.6)<br />

Urine Pb (µg/g creatinine)<br />

mean (SD, range):<br />

Pb: 84.0 (95.9, 21.8–587)<br />

Reference: 10.5<br />

(8.2, 1.7–36.9)<br />

Blood Pb (µg/dL) range:<br />

adult males: 10–60<br />

adult females: 7–53<br />

Significant association between increasing blood Pb concentration<br />

and increasing (log) blood EP (∀ = 0.06, ∃ = 0.019, r = 0.87,<br />

p = 0.0001) or (log) urine ALA (∀ = 0.37, ∃ = 0.008, r = 0.64,<br />

p < 0.0001)<br />

(No apparent analysis <strong>of</strong> covariables)<br />

Significantly lower (p = NR) P5N in Pb workers (males or females,<br />

or combined) compared to corresponding reference groups.<br />

Correlations with blood Pb:<br />

log P5N r = −0.79 (p < 0.001)<br />

log ALAD r = −0.97 (p = NR)<br />

R/ALAD r = −0.94 (p < 0.001)<br />

log EP r = 0.86 (p = NR)<br />

Correlations with urine Pb:<br />

log P5N r = −0.74 (p = NR)<br />

log ALAD r = −0.79 (p = NR)<br />

R/ALAD r = −0.84 (p < 0.001)<br />

log EP r = 0.80 (p = NR)<br />

Linear regression <strong>for</strong> EP (log-trans<strong>for</strong>med) and blood Pb<br />

concentration:<br />

adult male (n = 39): ∀ = 1.41, ∃ = 0.014, r = 0.74, p < 0.001<br />

adult female (n = 36): ∀ = 1.23, ∃ = 0.027, r = 0.81, p < 0.001<br />

Linear regression <strong>for</strong> ALA (log-trans<strong>for</strong>med) and blood Pb<br />

concentration:<br />

adult male (n = 39): ∀ = 0.37, ∃ = 0.006, r = 0.41, p < 0.01<br />

adult female (n = 36): ∀ = 0.15, ∃ = 0.015, r = 0.72, p < 0.001


AX6-224<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Grandjean (1979)<br />

Denmark<br />

NR<br />

Alessio et al. (1976)<br />

Italy<br />

NR<br />

Cocco et al. (1995)<br />

Italy<br />

1990<br />

Design: longitudinal<br />

Subjects: male battery manufacture workers<br />

(n = 19), mean age 32 yr (range 22–49)<br />

Outcome measures: EP<br />

Analysis: EP and blood Pb <strong>for</strong> serial<br />

measurements displayed graphically<br />

Design: cross-sectional<br />

Subjects: adult male Pb worker (n = 316), age<br />

range NR<br />

Outcome measures: blood ALAD, EP, urine<br />

ALA, CP<br />

Analysis: linear regression, correlation<br />

Design: longitudinal<br />

Subjects: adult male foundry workers<br />

(n = 40), mean age 25.1 yr (SD 2.1, range<br />

21–28)<br />

Outcome measures: serum total-, HDL- and<br />

LDL-cholesterol, blood Hgb, urine ALA,<br />

erythrocyte G6PD<br />

Analysis: comparison <strong>of</strong> outcomes between<br />

pre-exposure (at start <strong>of</strong> employment,<br />

sample 1) and after 172 (range 138–217,<br />

sample 2) days<br />

Blood Pb (µg/dL) median<br />

(range):<br />

Group 1 (n = 5): 47.7<br />

(22.8–53.9)<br />

Group 2 (n = 5): 37.3<br />

(35.2–53.9)<br />

Blood Pb (µg/dL) range:<br />

10–150<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Sample 1: 10.0 (7–15)<br />

Sample 2: 32.7 (20–51)<br />

Five subjects (group 1) showed declines in EP with declining<br />

blood Pb (33–58 µg/dL) over a 10-mo period; 5 subjects (group 2)<br />

showed no change in EP with a change in blood Pb concentration<br />

(25–54 µg/dL) over the same period.<br />

Regression relating outcomes to blood Pb concentration:<br />

ALAD (ln-trans<strong>for</strong>med) (n = 169): ∀ = 3.73, ∃ = −0.031, r = 0.871<br />

ALAU (ln-trans<strong>for</strong>med) (n = 316): ∀ = 1.25, ∃ = 0.014, r = 0.622<br />

UCP (ln-trans<strong>for</strong>med) (n = 252): ∀ = 2.18, ∃ = 0.34, r = 0.670<br />

EP (log-trans<strong>for</strong>med (males, n = 95): ∀ = 0.94, ∃ = 0.0117<br />

EP (log-trans<strong>for</strong>med (females, n = 93): ∀ = 1.60, ∃ = 0.0143<br />

G6PD levels were unrelated to starting blood Pb; however, they<br />

increased in subjects whose blood Pb concentration increased from<br />

30 µg/dL or decreased from >30 µg/dL to<br />

30 µg/dL subgroup, increasing blood Pb was associated<br />

with decreasing magnitude <strong>of</strong> change <strong>of</strong> G6PD (∃ = −2.0797 [SE<br />

0.7173], p < 0.05).<br />

Serum cholesterol levels were unrelated to blood Pb concentration.


AX6-225<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Fracasso et al. (2002)<br />

Italy<br />

NR<br />

Hernberg et al. (1970)<br />

Poland<br />

NR<br />

Bergdahl et al. (1997)<br />

Sweden<br />

NR<br />

Selander and Cramϑr<br />

(1970)<br />

Sweden<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult battery manufacture workers<br />

(n = 37, 6 females), mean age 41 yr (SD 7);<br />

reference <strong>of</strong>fice workers (n = 29, 8 females),<br />

mean age 38 yr (SD 21)<br />

Outcome measures: lymphocyte DNA strand<br />

breaks, ROS, GSH<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

(ANOVA), logistic regression<br />

Design: cross-sectional<br />

Subjects: adult Pb workers (n = 166);<br />

reference group (n = 16)<br />

Outcome measures: blood ALAD<br />

Analysis: regression, correlation<br />

Design: cross-sectional<br />

Subjects: adult smelter worker (n = 89);<br />

reference groups (n = 24)<br />

Outcome measures: blood Pb, erythrocyte<br />

ALAD-bound Pb, ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

Design: cross-sectional<br />

Subjects: adult battery manufacture workers<br />

(n = 177)<br />

Outcome measures: urine ALA<br />

Analysis: regression, correlation<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 39.6 (7.6)<br />

Reference: 4.4 (8.6)<br />

Blood Pb (µg/dL) range:<br />

5–95<br />

Blood Pb (µg/dL) range:<br />

0.8–93<br />

Urine Pb (mg/L) range:<br />

1–112<br />

Bone Pb (µg/g) range:<br />

−19–101<br />

Blood Pb (µg/dL) range:<br />

6–90<br />

Covariate-adjusted DNA strand breaks were significantly higher in<br />

Pb workers compared to the reference group and significantly<br />

associated with increased blood Pb (p = 0.011).<br />

Covariate-adjusted lymphocyte ROS was significantly higher and<br />

GSH significantly lower in the Pb workers compared to the<br />

reference group. Lower GSH levels were significantly associated<br />

with increasing blood Pb concentration (p = 0.006).<br />

Odds ratios (OR) <strong>for</strong> DNA strand breaks and lower GSH levels<br />

were significant (Pb workers vs. reference):<br />

DNA strand breaks: OR = 1.069 (95% CI: 1.020, 1.120),<br />

p = 0.005<br />

GSH: OR = 0.634 (95% CI: 0.488, 0.824), p = 0.001<br />

ROS: OR = 1.430 (95% CI: 0.787, 2.596), p = 0.855<br />

Covariates retained: age, alcohol consumption and tobacco<br />

smoking.<br />

Linear regression <strong>for</strong> blood ALAD (log-trans<strong>for</strong>med) and blood Pb<br />

concentration (n = 158):<br />

∀ = 2.274, ∃ = −0.018, r = −0.90, p < 0.001<br />

No association between ALAD genotype and Pb measures.<br />

Linear regression <strong>for</strong> urine ALA (log-trans<strong>for</strong>med) and blood Pb<br />

concentration (n = 150):<br />

∀ = −1.0985, ∃ = 0.0157, r = 0.74


AX6-226<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Wildt et al. (1987)<br />

Sweden<br />

NR<br />

Asia<br />

Hsieh et al. (2000)<br />

China<br />

NR<br />

Jiun and Hsien (1994)<br />

China<br />

1992<br />

Froom et al. (1999)<br />

Israel<br />

1980–1993<br />

Design: longitudinal<br />

Subjects: adult battery manufacture workers<br />

(n = 234, 37 females) mean age 35 y (range<br />

17–70); reference group (n = 951, 471<br />

females), mean age 39 yr (range 19–67)<br />

Outcome measures: EP<br />

Analysis: analysis <strong>of</strong> variability over time,<br />

linear regression, correlation<br />

Design: cross-sectional<br />

Subjects: Adults in general population<br />

(n = 630, 255 females)<br />

Outcome measures: blood Hgb, Hct, RBC<br />

count, ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Design: longitudinal<br />

Subjects: adult male Pb workers (n = 62),<br />

ages NR; reference group (n = 62, 40 females),<br />

ages NR<br />

Outcome measures: plasma MDA<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group,<br />

linear regression<br />

Design: longitudinal survey<br />

Subjects: adult male battery manufacturing<br />

workers (n = 94), mean age, 38 yr (SD 9,<br />

range 26–60)<br />

Outcome measures: blood Hgb, blood EP<br />

Analysis: multivariate linear regression<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Pb: 10–80<br />

Reference:<br />

Male: 11.3 (8–27)<br />

Female: 8.5 (5–21)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

ALAD1,1 (n = 630):<br />

6.5 (5.0)<br />

ALAD1,1/2,2 (n = 30):<br />

7.8 (6.0)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 37.2<br />

(12.5, 18.2–76.0)<br />

Reference: 13.4<br />

(7.5, 4.8–43.9)<br />

Blood Pb (µg/dL) range <strong>of</strong><br />

13-yr individual subject<br />

means:<br />

20–61 µg/dL<br />

Linear regression <strong>for</strong> EP (log-trans<strong>for</strong>med) and blood Pb<br />

concentration:<br />

Males (n = 851): ∀ = 1.21, ∃ = 0.0148, r = 0.72<br />

Females (n = 139): ∀ = 1.48, ∃ = 0.0113, r = 0.56<br />

Mean blood Pb not different between ALAD genotype strata<br />

(p = 0.17). RBC count, Hgb, Hct not different between ALAD<br />

genotype strata (p = 0.7)<br />

Plasma MDA levels significantly (p < 0.0001) higher (~2x) in Pb<br />

workers whose blood Pb concentration 35 µg/dL compared to<br />

#30 µg/dL. In subjects with blood Pb >35 µg/dL, blood Pb and<br />

plasma MDA were significantly correlated:<br />

blood Pb = 9.584(MDA) + 24.412 (r = 0.85)<br />

Weak (and probably not significant) covariate-adjusted association<br />

between blood Hgb and individual sample blood Pb (∃ = −0.0039<br />

[SE 0.0002]), subject avg blood Pb (∃ = −0.0027 [SE 0.0036]), or<br />

blood EP (∃ = −0.001 [SE 0.0007])<br />

Covariates retained in model were age and smoking habits.


AX6-227<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Kristal-Boneh et al.<br />

(1999)<br />

Israel<br />

1994–1995<br />

Solliway et al. (1996)<br />

Israel<br />

NR<br />

Ito et al. (1985)<br />

Japan<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 56), mean age 43.1 yr (SD 10.6);<br />

reference group (n = 87), mean age 43.2 yr<br />

(SD 8.3)<br />

Outcome measures: serum total-, HDL-, LDLcholesterol,<br />

HDL: total ratio, triglycerides<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

(ANOVA), multivariate linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 34), mean age: 44 yr (SD 13);<br />

reference subjects (n = 56), mean age 43 yr<br />

(SD 12); cohorts constructed to have similar<br />

age, ethnic characteristics, socioeconomic<br />

status, education level, and occupation<br />

Outcome measures: urinary ALA, erythrocyte<br />

GSH-peroxidase<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures between Pb and reference groups,<br />

correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult male steel (smelting, casting)<br />

workers (n = 712), age range 18–59 yr;<br />

reference (<strong>of</strong>fice workers) group (n = 155,<br />

total), age range 40–59 yr<br />

Outcome measures: serum LPO and SOD,<br />

total and HDL-cholesterol, phospholipid<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group,<br />

correlation<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 42.3 (14.9)<br />

Reference: 2.7 (3.6)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 40.7 (9.8, 23–63)<br />

Reference: 6.7 (2.4, 1–13)<br />

Blood Pb (µg/dL) range:<br />

Pb: 5–62<br />

Reference: NR<br />

Covariate-adjusted serum total-cholesterol (p = 0.016) and HDLcholesterol<br />

(p = 0.001) levels were significantly higher in Pb<br />

workers compared to reference group. Covariates retained in<br />

ANOVA: age, body mass index, season <strong>of</strong> sampling, nutritional<br />

variables (dietary fat, cholesterol, calcium intakes), sport activities,<br />

alcohol consumption, cigarette smoking, education, job seniority.<br />

Increasing blood Pb concentration was significantly associated<br />

with covariate-adjusted total cholesterol (∃ = 0.130 [SE 0.054],<br />

p = 0.017) and HDL-cholesterol (∃ = 0.543 [SE 0.173], p = 0.002).<br />

Covariates retained: age, body mass index. Stepwise inclusion <strong>of</strong><br />

other potential confounders had no effect.<br />

Significantly lower mean erythrocyte GSH-peroxidase activity<br />

(p < 0.005) in and higher urinary ALA (p < 0.001) in Pb workers<br />

compared to reference group.<br />

When stratified by age, significantly (p < 0.05) higher serum HDLcholesterol<br />

and LPO in Pb workers, age range 40–49 yr, compared<br />

to corresponding strata <strong>of</strong> reference group. Serum lipoperoxide<br />

levels increased as blood Pb increased above 30 µg/dL (p = NR),<br />

SOD appeared to decrease with increasing blood Pb concentration<br />

(p = NR)


AX6-228<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Makino et al. (1997)<br />

Japan<br />

1990–1994<br />

Morita et al. (1997)<br />

Japan<br />

NR<br />

Oishi et al. (1996)<br />

Japan<br />

NR<br />

Design: longitudinal survey<br />

Subjects: adult male pigment or vinyl chloride<br />

stabilizer manufacture workers (n = 1573)<br />

mean age 45 yr<br />

Outcome measures: blood Hgb, Hct,<br />

RBC count<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures, stratified by blood Pb, linear<br />

regression<br />

Design: cross-sectional cohort<br />

Subjects: male Pb workers (n = 76), mean age<br />

42 yr (range 21–62); reference subjects<br />

(n = 13, 6 females), mean age, males 41 yr<br />

(range 26–52), females 45 yr (range 16–61)<br />

Outcome measures: blood NADS, ALAD<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

(ANOVA) between blood Pb categories, linear<br />

regression<br />

Design: cross-sectional<br />

Subjects: adult glass and pigment manufacture<br />

workers (n = 418, 165 females), mean age 33<br />

yr (range 18–58); reference workers (n = 227,<br />

89 females), mean age 30 yr (range 17–59)<br />

Outcome measures: plasma ALA, urinary<br />

ALA<br />

Analysis: linear regression, correlation<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

12.6 (2.0, 1–39)<br />

Urine Pb (µg/L) mean<br />

(SD, range):<br />

10.2 (2.7, 1–239)<br />

Blood Pb (µg/dL) mean<br />

(SD, range)<br />

Pb: 34.6 (20.7, 2.2–81.6)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 48.5 (17.0, 10.3–99.4<br />

Reference: 9.6 (3.3, 3.8–<br />

20.4)<br />

Significantly higher (p < 0.001) Hct, blood Hgb and RBC count in<br />

blood Pb category 16–39 µg/dL, compared to 1–15 µg/dL<br />

category.<br />

Significant positive correlation between blood Pb concentration<br />

and Hct: ∀ = 42.95, ∃ = 0.0586 (r = 0.1553, p < 0.001), blood<br />

Hgb: ∀ = 14.65, ∃ = 0.0265 (r = 0.1835, p < 0.001) and RBC<br />

count ∀ = 457, ∃ = 0.7120 (r = 0.1408, p < 0.001).<br />

Significantly lower (p < 0.01) blood NADS and ALAD in blood Pb<br />

categories >20 µg/dL compared to


AX6-229<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Sugawara et al. (1991)<br />

Japan<br />

NR<br />

Kim et al. (2002)<br />

Korea<br />

1996<br />

Lee et al. (2000)<br />

Korea<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult Pb workers and reference<br />

group (n = 32, total), ages NR<br />

Outcome measures: plasma and erythrocyte<br />

lipoperoxide and SOD; erythrocyte CAT,<br />

GSH, and methemoglobin<br />

Analysis: comparisons <strong>of</strong> outcome measures<br />

between Pb workers and reference group,<br />

linear regression and correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult male secondary Pb smelter<br />

workers (n = 83), mean age: 38.7 yr (SD<br />

10.8); reference subjects (n = 24), mean age:<br />

32.0 (SD 10.8)<br />

Outcome measures: blood Hgb, blood ALAD,<br />

blood EP, blood P5N<br />

Analysis: parametric comparison (ANOVA)<br />

<strong>of</strong> outcome measures between Pb workers and<br />

reference group, correlation, multivariate<br />

linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb workers (n = 95;<br />

secondary smelter, PVC-stabilizer<br />

manufacture, battery manufacture); mean age<br />

42.8 yr (SD 9.3, range 19–64); reference group<br />

(n = 13), mean age 35.1 yr (SD 9.9, range<br />

22–54)<br />

Outcome measures: urinary ALA, EP<br />

Analysis: correlation<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 57.1 (17.6, 20–96)<br />

Reference: NR<br />

Blood Pb (µg/dL) mean<br />

(SD)<br />

Pb: 52.4 (17.7)<br />

Reference: 6.2 (2.8)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 44.6 (12.6, 21.4–78.4)<br />

Reference: 5.9<br />

(1.2, 4.0–7.2)<br />

Significantly (p < 0.01) higher erythrocyte LPO and lower SOD,<br />

CAT and GSH levels in workers compared to reference group.<br />

Erythrocyte lipoperoxide (r = 0.656) and GSH (r = −0.631) were<br />

significantly correlated with blood Pb.<br />

Significantly (p < 0.05) lower blood P5N, ALAD, and Hgb; and<br />

higher blood EP in Pb workers compared to controls.<br />

Significant (p < 0.001) correlations (in Pb worker group) with<br />

blood Pb: P5N (r = −0.704), log EP (r = 0.678), log ALAD<br />

(r = −0.622).<br />

Significant association between increasing EP and decreasing<br />

blood Hgb:<br />

blood Pb ∃60 µg/dL: ∃ = −1.546 (95% CI: −2.387, −0.704),<br />

r 2 = 0.513, p = 0.001<br />

blood Pb


AX6-230<br />

Table 6-9.2 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Biochemical Effects in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Schwartz et al. (1997)<br />

Korea<br />

1994-1995<br />

Gurer-Orhan et al.<br />

(2004)<br />

Turkey<br />

NR<br />

Süzen et al. (2003)<br />

Turkey<br />

NR<br />

Design: cross-sectional<br />

Subjects: adult male battery manufacture<br />

workers (n = 57), mean age 32 yrs (SD 6).<br />

Outcome measures: blood Hgb, HgbA1, and<br />

Hgb A2, ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 20), mean age 35 yr (SD 8);<br />

reference workers (n = 16), mean age<br />

32 yr (SD 9)<br />

Outcome measures: blood ALAD, EP,<br />

erythrocyte MDA, CAT, G6PD, blood<br />

GSH:GSSG<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group,<br />

correlation<br />

Design: cross-sectional<br />

Subjects: Male Pb battery manufacture<br />

workers (n = 72), age range 24-45 yrs.<br />

Outcome measures: blood ALAD, urine ALA,<br />

ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

ALAD1,1 (n = 38): 26.1<br />

(9.8)<br />

ALAD1,2 (n = 19): 24.0<br />

(11.3)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 54.6 (17)<br />

Reference: 11.8 (3.2)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

All: 34.5 (12.8, 13.4–71.8)<br />

ALAD1,1 (n = 51)<br />

34.4 (13.1, 13.4–71.8)<br />

ALAD2 (n = 21)<br />

34.9 (12.6, 19.2–69.6)<br />

Mean blood Pb (p = 0.48) and blood Hgb levels (p = 0.34) were<br />

not different between ALAD genotype strata.<br />

Significant correlation between blood Pb concentration and blood<br />

ALAD (r = -0.85, p < 0.0001) and EP (r = 0.83, p < 0.001).<br />

Significant correlation between blood Pb concentration and<br />

erythrocyte MDA (r = 0.80, p =


AX6-231<br />

Table AX6-9.3. Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Liebelt et al. (1999)<br />

Connecticut<br />

NR<br />

Schwartz et al. (1990)<br />

Idaho<br />

1974<br />

Design: cross-sectional<br />

Subjects: children (n = 86, 31 female), ages<br />

1–6 yr<br />

Outcome measures: serum EPO, blood Hgb<br />

Analysis: ANOVA <strong>of</strong> outcome measures<br />

stratified by blood Pb, linear regression<br />

Design: cross-sectional<br />

Subjects: children (n = 579), ages 1–5 yr,<br />

residing near an active smelter (with<br />

uncontrolled emissions)<br />

Outcome measures: Hct<br />

Analysis: logistic regression<br />

Blood Pb (µg/dL) median<br />

(range):<br />

18 (2–84)<br />

84%


AX6-232<br />

Table AX6-9.3 (cont’d.). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe<br />

Graziano et al. (2004)<br />

(Factor Litvak et al.<br />

(1999, 1998)<br />

Yugoslavia<br />

1985–1998<br />

Design: prospective<br />

Subjects: children (n = 311; age range<br />

4.5–12 yr) from high-Pb (smelter/refinery)<br />

and low-Pb areas<br />

Outcome measures: blood Hgb, serum EPO.<br />

Analysis: multivariate linear regression<br />

(GEE <strong>for</strong> repeated measures)<br />

Blood Pb (µg/dL) range:<br />

4.5 yr: 4.6–73.1<br />

6.5 yr: 3.1–71.7<br />

9.0 yr: 2.3–58.1<br />

Blood Pb (µg/dL) means<br />

<strong>for</strong> ages 4.5–12 yrs:<br />

High Pb: 30.6–39.3<br />

Low Pb: 6.1–9.0<br />

Significant association between increasing blood Pb concentration<br />

and increasing serum EPO concentration at ages 4.5 (p < 0.0001)<br />

and 6.5 yr (p < 0.0007), with decreasing regression slope with age:<br />

4.5 yr: ∃ = 0.21 (SE 0.043), p = 0.0001; 6.5 yr: ∃ = 0.11 (SE 0.41),<br />

p = 0.0103; 9.5 yr: ∃ = 0.029 (SE 0.033), p = 0.39; 12 yr: ∃ = 0.016<br />

(SE 0.031), p = 0.60.<br />

Covariates retained in regression model were age (∀), blood Pb (∃),<br />

and blood Hgb ((). GEE <strong>for</strong> repeated measures yielded (Factor-<br />

Litvak et al., 1998, updated from personal communication from<br />

Graziano 07/2005):<br />

(: 0.6097 (95% CI: −0.0915, −0.0479), p < 0.0001<br />

4.5 yr: ∀ = 1.3421 (95% CI: 1.0348, 1.6194), p < 0.0001<br />

∃ = 0.2142 (95% CI: 0.1282, 0.3003), p < 0.0001<br />

6.5 yr: ∀ = 1.6620 (95% CI: 1.3737, 1.9503), p < 0.0001<br />

∃ = 0.1167 (95% CI: 0.0326, 0.2008), p < 0.001<br />

9.5 yr: ∀ = 1.7639 (95% CI: 1.4586, 2.0691), p < 0.0001<br />

∃ = 0.0326 (95% CI: −0.0346, 0.0998), p = 0.1645<br />

12 yr: ∀ = 1.8223 (95% CI: 1.524, 2.1121), p < 0.0001<br />

∃ = 0.0112 (95% CI: −0.0359, 0.0584), p = 0.1645<br />

Based on the GEE, the predicted increase in serum EPO per 10<br />

µg/dL increase in blood Pb concentration (at Hgb = 13 g/dL) \ was:<br />

1.25 mIU/mL (36%) at age 4.5 yr and 1.18 (18%) at age 6.5 yr.<br />

Blood Hgb levels were not significantly different in children from<br />

high-Pb area (mean 25–38 µg/dL) compared to low-Pb area (mean<br />

5–9 µg/dL).


AX6-233<br />

Table AX6-9.3 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

Perez-Bravo et al.<br />

(2004)<br />

Chile<br />

NR<br />

Design: cross-sectional;<br />

Subjects: children (n = 93, 43 males), aged<br />

5-12 yrs who attended school near a<br />

powdered Pb storage facility<br />

Outcome measures: blood Hgb and Hct,<br />

ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Blood Pb (µg/dL) mean<br />

(SE):<br />

ALAD1 (n = 84): 13.5<br />

(8.7)<br />

ALAD2 (n = 9): 19.2 (9.5)<br />

Mean blood Pb, blood Hgb, and Hct not different between ALAD<br />

genotypes


AX6-234<br />

Table AX6-9.4. Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Hu et al. (1994)<br />

U.S.<br />

1991<br />

Europe<br />

Osterode et al. (1999)<br />

Austria<br />

NR<br />

Design: survey<br />

Subjects: adult male carpentry workers<br />

(n = 119), mean age: 48.6 yr (range 23–67)<br />

Outcome measures: blood Hct, blood Hgb<br />

Analysis: multivariate linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb workers (n = 20),<br />

ages 46 yr (SD, 7); age-matched reference<br />

group (n = 20)<br />

Outcome measures: blood PCV, blood Hgb,<br />

serum EPO, blood erythroid progenitor<br />

(BFU-E) cell count, blood pluripotent<br />

progenitor (CFU-GEMM) cell count, blood<br />

granulocyte/macrophage progenitor (CFU-<br />

GM) cell count.<br />

Analysis: parametric and nonparametric<br />

comparison <strong>of</strong> outcomes between Pb workers<br />

and reference group; correlation<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

8.3 (4.0, 2–25)<br />

Bone Pb (µg/g) mean<br />

(SD, range)<br />

Tibia: 9.8 (9.5, −15 to 39)<br />

Patella: 13.9 (16.6, −11 to<br />

78)<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Pb: 45.5 (16–91)<br />

Reference: 4.1 (3–14)<br />

Urine Pb (µg/L) mean<br />

(range):<br />

Pb: 46.6 (7–108)<br />

Reference: 3.7 (2–16)<br />

Significant association between increasing patella bone Pb and<br />

decreasing covariate adjusted blood Hgb (∃ = −0.019 [SE 0.0069],<br />

p = 0.008, r 2 = 0.078) and blood Hct (∃ = −0.052 [SE 0.019],<br />

p = 0.009, r 2 = 0.061). After adjustment <strong>for</strong> bone Pb measurement<br />

error, a 37 µg/dL increase in patella bone Pb level (from the lowest<br />

to highest quintile) was associated with a decrease in blood Hgb and<br />

Hct <strong>of</strong> 11 g/L (95% CI: 2.7, 19.3) and 0.03 (95% CI: 0.01, 0.05),<br />

respectively.<br />

Covariates considered: age, body mass index, tibia Pb, patella Pb,<br />

blood Pb, current smoking status, alcohol consumption<br />

Covariates retained: patella bone Pb, alcohol consumption, body<br />

mass index.<br />

Significantly lower (p < 0.001) BFU-E counts in Pb workers who<br />

had blood Pb concentrations ∃60 µg/dL, compared to reference<br />

group. Significant negative correlation between blood Pb or urine<br />

Pb and CFU-GM and CFU-E. Serum EPO was not correlated with<br />

Hct in Pb workers, however, serum EPO increased exponentially<br />

with decrease in Hct in reference group.


AX6-235<br />

Table AX6-9.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Gennart et al. (1992)<br />

Belgium<br />

NR<br />

Mohammed-Brahim<br />

et al. (1985)<br />

Belgium<br />

NR<br />

Hajem et al. (1990)<br />

France<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult battery manufacture workers<br />

(n = 98), mean age, 37.7 yr (range 22–55);<br />

reference group (n = 85), mean age 38.8 yr<br />

(24–55)<br />

Outcome measures: blood Hgb, RBC count,<br />

Hct, blood EP<br />

Analysis: linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult smelter and ceramics<br />

manufacture workers (n = 38, 13 females);<br />

reference subjects (n = 100) matched with<br />

worker group by age, sex, and<br />

socioeconomic status<br />

Outcome measures: blood P5N, EP, ALAD,<br />

R/ALAD (ratio <strong>of</strong> ALAD be<strong>for</strong>e and after<br />

reactivation).<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

(ANOVA) between Pb workers and<br />

reference group; correlation<br />

Design: cross-sectional<br />

Subjects: adult males (n = 129), mean age<br />

36 yr (SD 7.8, range 24–55), with no<br />

environmental exposure to Pb<br />

Outcome measures: erythrocyte membrane<br />

activities <strong>of</strong> Na+-K+-ATPase, Na+-K+-cotransport,<br />

Na+-Li+-antiport, and passive Na+<br />

and K+ permeability<br />

Analysis: linear regression, correlation<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 51.0 (8.0, 40–70)<br />

Reference: 20.9 (11.1, 4.4–<br />

30.0)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 48.5 (9.1, 27.8–66.6)<br />

Reference: 14.3 (6.7, 5.6–<br />

33.6)<br />

Urine Pb (µg/g creatinine)<br />

mean (SD, range):<br />

Pb: 84.0 (95.9, 21.8–587)<br />

Reference: 10.5 (8.2, 1.7–<br />

36.9)<br />

Blood Pb (µg/dL)<br />

geometric mean (95% CI,<br />

range):<br />

16.0 (15.2–16.8, 8.0–33.0)<br />

Hair Pb (µg/g) geometric<br />

mean (95% CI, range):<br />

5.3 (4.44–6.23, 0.9–60)<br />

Significant association between increasing blood Pb concentration<br />

and decreasing blood Hgb (∃ = −0.011, r = 0.22, p = 0.003) or Hct<br />

(∃ = -0.035, r = 0.24, p < 0.01).<br />

Significant association between increasing blood Pb concentration<br />

and increasing blood EP (∃ = 0.0191, r = 0.87, p = 0.0001)<br />

(No apparent analysis <strong>of</strong> covariables).<br />

Significantly lower (p = NR) P5N in Pb workers (males or females,<br />

or combined) compared to corresponding reference groups.<br />

Correlations with blood Pb:<br />

log P5N r = −0.79 (p < 0.001)<br />

log ALAD r = −0.97 (p = NR)<br />

R/ALAD r = −0.94 (p < 0.001)<br />

log EP r = 0.86 (p = NR)<br />

Correlations with urine Pb:<br />

log P5N r = −0.74 (p = NR)<br />

log ALAD r = −0.79 (p = NR)<br />

R/ALAD r = −0.84 (p < 0.001)<br />

log EP r = 0.80 (p = NR)<br />

Na+-K+-co-transport activity negatively correlated with blood Pb<br />

concentration (r = −0.23, p = 0.02); linear regression:<br />

∀ = 583.19, ∃ = −170.70<br />

Na+-K+-ATPase activity negatively correlated with hair Pb<br />

(r = −0.18, p = 0.04); simple linear regression:<br />

∀ = 3.34, ∃ = −0.02


AX6-236<br />

Table AX6-9.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Poulos et al. (1986)<br />

Greece<br />

NR<br />

Romeo et al. (1996)<br />

Italy<br />

NR<br />

Graziano et al. (1990)<br />

Yugoslavia<br />

1986<br />

Design: cross-sectional cohort<br />

Subjects: adult male cable production<br />

workers who were exposed to Pb (worker 1;<br />

n = 50, mean age 37 yr); male cable workers<br />

who had not direct contact with Pb (worker<br />

2, n = 75, mean age 36.5 yr); reference group<br />

(n = 35, mean age 39 yr)<br />

Outcome measures: blood Hgb, Hct<br />

Analysis: simple linear regression in the<br />

<strong>for</strong>m: mean Hct = a + ∃(individual Hct –<br />

group mean Hct)<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb workers (n = 28),<br />

age range, 17–73; reference group (n = 113),<br />

age range, 21–75 yr<br />

Outcome measures: serum EPO, blood Hgb<br />

Analysis: nonparametric comparison <strong>of</strong><br />

outcome measures between Pb workers and<br />

reference group; correlation<br />

Design: prospective<br />

Subjects: pregnant women (n = 1502) from<br />

high-Pb (smelter/refinery) and low-Pb areas<br />

Outcome measures: Hgb<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between high-and low-Pb groups<br />

Blood Pb (µg/dL) mean<br />

(SE):<br />

Worker 1: 27.0 (0.7)<br />

Worker 2: 18.3 (0.6)<br />

Reference: 21.5 (1.5)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb 1: 32.3 (5.6, 30–49)<br />

Pb 2: 65.1 (16, 50–92)<br />

Reference: 10.4 (4.3, 3–<br />

20)<br />

Blood Pb (µg/dL) mean<br />

(95% CI):<br />

High Pb: 17.1 (6.9, 42.6)<br />

Low Pb: 5.1 (2.5, 10.6)<br />

Significant association between increasing blood Pb and decreasing<br />

Hct:<br />

Worker 1: ∀ = 46.50, ∃ = −0.170 (SE 0.079), p < 0.05<br />

Worker 2: ∀ = 44.57, ∃ = −0.180 (SE 0.083), p < 0.05<br />

Reference: ∀ = 44.69, ∃ = −0.255 (SE 0.044), p < 0.001<br />

Significant association between increasing blood Pb and decreasing<br />

blood Hgb:<br />

Worker 1: ∀ = 15.23, ∃ = −0.058 (SE 0.028), p < 0.05<br />

Worker 2: ∀ = 14.58, ∃ = −0.071 (SE 0.034), p < 0.05<br />

Reference: ∀ = 14.64, ∃ = −0.087 (SE 0.015), p < 0.001<br />

Significantly (p = 0.021) lower serum EPO in Pb workers compared<br />

to reference group. No significant (p < 0.05) Pb effect on blood<br />

Hgb.<br />

Mean blood Hgb levels (g/dL) in high-Pb group (12.4; 95% CI:<br />

10.3, 14.5) not different from low-Pb group (12.3; 95% CI: 10.0,<br />

14.7).


AX6-237<br />

Table AX6-9.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Graziano et al. (1990)<br />

Yugoslavia<br />

1986<br />

Asia<br />

Hsiao et al. (2001)<br />

China<br />

1989–1999<br />

Hsieh et al. (2000)<br />

China<br />

NR<br />

Design: prospective<br />

Subjects: pregnant women (n = 48) from<br />

high-Pb (smelter/refinery) and low-Pb areas<br />

(6 highest and lowest mid-pregnancy blood<br />

Pb concentrations), within each <strong>of</strong> 4 Hgb<br />

strata (g/dL): 9.0–9.9, 10.0–10.9, 11.0–11.9,<br />

12.0–12.9<br />

Outcome measures: Hgb, EPO<br />

Analysis: ANOVA <strong>of</strong> outcome measures in<br />

subjects stratified by blood Pb and blood<br />

Hgb<br />

Design: longitudinal<br />

Subjects: adult battery manufacture workers<br />

(n = 30, 13 females), mean age 38.3 yr<br />

Outcome measures: blood Hgb, Hct,<br />

RBC count<br />

Analysis: GEE <strong>for</strong> repeated measures<br />

(models: linear correlation, threshold<br />

change, synchronous change, lag change);<br />

logistic regression<br />

Design: cross-sectional<br />

Subjects: Adults in general population<br />

(n = 630, 255 females)<br />

Outcome measures: blood Hgb, Hct, RBC<br />

count, ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Blood Pb (µg/dL) mean<br />

range <strong>for</strong> Hgb strata<br />

High Pb: 16.9–38.6<br />

Low Pb: 2.4–3.6<br />

Blood Pb (µg/dL) mean:<br />

1989: 60<br />

1999: 30<br />

Blood Pb ( µg/dL) mean<br />

(SD):<br />

ALAD1,1 (n = 630):<br />

6.5 (5.0)<br />

ALAD1,1/2,2 (n = 30):<br />

7.8 (6.0)<br />

Significant effect <strong>of</strong> blood Pb (p = 0.049) and blood Hgb (p = 0.001)<br />

on mid-term and term serum EPO (blood Pb p = 0.055, Hgb<br />

p = 0.009), with significantly lower serum EPO associated with<br />

higher blood Pb.<br />

Significant association between increasing blood Pb and increasing<br />

RBC count and Hct:<br />

Odds ratios (95% CI):<br />

Synchronous change model:<br />

Blood Hgb: 0.95 (0.52, 1.78)<br />

RBC count: 3.33 (1.78, 6.19)<br />

Hct: 2.19 (1.31, 3.66)<br />

Lag change:<br />

Blood Hgb: 1.70 (0.99, 2.92)<br />

RBC count: 2.26 (1.16, 4.41)<br />

Hct: 2.08 (1.16, 4.41)<br />

Mean blood Pb not different between ALAD genotype strata<br />

(p = 0.17). RBC count, Hgb, Hct not different between ALAD<br />

genotype strata (p = 0.7).


AX6-238<br />

Table AX6-9.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Froom et al. (1999)<br />

Israel<br />

1980–1993<br />

Solliway et al. (1996)<br />

Israel<br />

NR<br />

Horiguchi et al. (1991)<br />

Japan<br />

NR<br />

Design: longitudinal survey<br />

Subjects: adult male battery manufacturing<br />

workers (n = 94), mean age, 38 yr (SD 9,<br />

range 26–60)<br />

Outcome measures: blood Hgb, blood EP<br />

Analysis: multivariate linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 34), mean age: 44 yr (SD 13);<br />

reference subjects (n = 56), mean age 43 yr<br />

(SD 12); cohorts constructed to have similar<br />

age, ethnic characteristics, socioeconomic<br />

status, education level, and occupation<br />

Outcome measures: blood Hgb, RBC count<br />

Analysis: parametric comparison <strong>of</strong><br />

outcome measures between Pb and reference<br />

groups, correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult male secondary Pb refinery<br />

workers (n = 17), mean age: 44.9 yr (range<br />

24–58); reference male subjects (n = 13),<br />

mean age: 33.5 yr (range 22–44)<br />

Outcome measures: RBC de<strong>for</strong>mability<br />

(micr<strong>of</strong>iltration at −20 cm H2O pressure),<br />

RBC count, Hct, blood Hgb<br />

Analysis: comparisons <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

Blood Pb (µg/dL) range <strong>of</strong><br />

13-yr individual subject<br />

means: 20–61 µg/dL<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 40.7 (9.8, 23–63)<br />

Reference: 6.7 (2.4, 1–13)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 53.5 (16.1)<br />

Reference: NR<br />

Urine Pb (µg/L) mean<br />

(SD):<br />

Pb: 141.4 (38.1)<br />

Reference: NR<br />

Weak (and probably not significant) covariate-adjusted association<br />

between blood Hgb and individual sample blood Pb (∃ = −0.0039<br />

[SE 0.0002]), subject avg blood Pb (∃ = −0.0027 [SE 0.0036]) or<br />

blood EP (∃ = −0.001 [SE 0.0007]).<br />

Covariates retained in model were age and smoking habits.<br />

Significantly lower (p < 0.05) mean RBC count in Pb workers<br />

compared to reference group. Significant negative correlation<br />

between blood Pb concentration and RBC count (r = −0.29,<br />

p < 0.05). Mean comparison <strong>for</strong> blood Hgb (p = 0.4); correlation<br />

with blood Pb concentration (r = −0.05, p = 0.7).<br />

Significantly lower RBC de<strong>for</strong>mability (p < 0.01), RBC count<br />

(p < 0.01) Hct (p < 0.01), and blood Hgb (p > 0.001) in Pb workers<br />

compared to reference group.


AX6-239<br />

Table AX6-9.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Makino et al. (1997)<br />

Japan<br />

1990–1994<br />

Morita et al. (1997)<br />

Japan<br />

NR<br />

Kim et al. (2002)<br />

Korea<br />

1996<br />

Design: longitudinal survey<br />

Subjects: adult male pigment or vinyl<br />

chloride stabilizer manufacture workers<br />

(n = 1573) mean age 45 yr<br />

Outcome measures: blood Hgb, Hct, RBC<br />

count<br />

Analysis: parametric comparison <strong>of</strong><br />

outcome measures, stratified by blood Pb,<br />

linear regression<br />

Design: cross-sectional cohort<br />

Subjects: male Pb workers (n = 76), mean<br />

age 42 yr (range 21–62); reference subjects<br />

(n = 13, 6 females), mean age, males 41 yr<br />

(range 26–52), females 45 yr (range 16–61)<br />

Outcome measures: blood NADS, ALAD<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

(ANOVA) between blood Pb categories,<br />

linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male secondary Pb smelter<br />

workers (n = 83), mean age: 38.7 yr (SD<br />

10.8); reference subjects (n = 24), mean age:<br />

32.0 (SD 10.8)<br />

Outcome measures: blood Hgb, blood<br />

ALAD, blood EP, blood P5N<br />

Analysis: parametric comparison (ANOVA)<br />

<strong>of</strong> outcome measures between Pb workers<br />

and reference group, correlation, multivariate<br />

linear regression<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

12.6 (2.0, 1–39)<br />

Urine Pb (µg/L) mean (SD,<br />

range):<br />

10.2 (2.7, 1–239)<br />

Blood Pb (µg/dL) mean<br />

(SD, range)<br />

Pb: 34.6 (20.7, 2.2–81.6)<br />

Blood Pb (µg/dL) mean<br />

(SD)<br />

Pb: 52.4 (17.7)<br />

Reference: 6.2 (2.8)<br />

Significantly higher (p < 0.001) Hct, blood Hgb, and RBC count in<br />

blood Pb category 16–39 µg/dL, compared to 1–15 µg/dL category.<br />

Significant positive correlation between blood Pb concentration and<br />

Hct: ∀ = 42.95, ∃ = 0.0586 (r = 0.1553, p < 0.001), blood Hgb:<br />

∀ = 14.65, ∃ = 0.0265 (r = 0.1835, p < 0.001), and RBC count<br />

∀ = 457, ∃ = 0.7120 (r = 0.1408, p < 0.001).<br />

Significantly lower (p < 0.01) blood NADS and ALAD in blood Pb<br />

categories >20 µg/dL compared to


AX6-240<br />

Table AX6-9.4 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Hematopoietic System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Schwartz et al. (1997)<br />

Korea<br />

1994-1995<br />

Design: cross-sectional<br />

Subjects: adult male battery manufacture<br />

workers (n = 57), mean age 32 yrs (SD 6).<br />

Outcome measures: blood Hgb, HgbA1, and<br />

Hgb A2, ALAD genotype<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between ALAD genotype strata<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

ALAD1,1 (n = 38): 26.1<br />

(9.8)<br />

ALAD1,2 (n = 19): 24.0<br />

(11.3)<br />

Mean blood Pb (p = 0.48) and blood Hgb levels (p = 0.34) were not<br />

different between ALAD genotype strata.


AX6-241<br />

Table AX6-9.5. Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Mahaffey et al. (1982)<br />

Wisconsin, New York<br />

NR<br />

Rosen et al. (1980)<br />

New York<br />

NR<br />

Sorrell et al. (1977)<br />

New York<br />

1971–1975<br />

Design: cross-sectional<br />

Subjects: children/adolescents (n = 177),<br />

ages 1–16 yr<br />

Outcome measures: serum 1,25-OH-D<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between age, location and blood Pb strata,<br />

linear regression<br />

Design: cross-sectional<br />

Subjects: children (n = 45), ages 1–5 yr<br />

Outcome measures: serum calcium, PTH,<br />

25-OH-D, 1,25-OH-D<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between blood Pb strata, and be<strong>for</strong>e and after<br />

chelation, correlation<br />

Design: cross-sectional<br />

Subjects: children (124), ages 1–6 yr<br />

Outcome measures: serum calcium,<br />

phosphate, 25-OH-D<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between blood Pb strata, correlation<br />

Blood Pb (µg/dL) range:<br />

12–120<br />

Blood Pb (µg/dL) mean<br />

(SE, range):<br />

#29 (n = 15): 18<br />

(1, 10–26)<br />

30–59 (n = 18): 47<br />

(2, 33–55)<br />

∃60 (n = 12): 74<br />

(98, 62–120)<br />

Blood Pb (µg/dL) mean<br />

(SE):<br />

#29 (n = 40): 23 (1)<br />

30–59 (n = 35): 48 (1)<br />

∃60 (n = 49): 84 (5.0)<br />

Serum 1,25-OH-D levels were significantly (p = 0.05) higher in the<br />

age group 11–16 yr compared to age groups 1–5 or 6–10 yr.<br />

Increasing blood Pb (log-trans<strong>for</strong>med) significantly associated with<br />

decreasing serum 1,25-OH-D levels in children 1–5 yr <strong>of</strong> age<br />

(∀ = 74.5, ∃ = −34.5, r = −0.884, n = 50)<br />

Dietary calcium: NR<br />

Significantly higher serum PTH levels and lower 25-OH-D in high-<br />

Pb group compared to low-Pb group; significantly lower 1,25-OH-D<br />

levels in moderate- and high-Pb group compared to low-Pb group.<br />

Serum levels <strong>of</strong> 1,25-OH-D were negatively correlated with blood<br />

Pb (high Pb: r = −0.71, moderate: r = −0.63, p < 0.01). After<br />

chelation therapy, blood Pb decreased and serum 1,25-OH-D levels<br />

increased to levels not significantly different (p > 0.1) from low-Pb<br />

group, 25-OH-D levels were unchanged.<br />

Dietary calcium intake (mg/day) mean (SE):<br />

Low Pb: 800 (30)<br />

Moderate Pb: 780 (25)<br />

High Pb: 580 (15)<br />

Serum calcium and 25-OH-D were significantly lower in high Pb<br />

group (p < 0.001). Significant negative correlation between blood<br />

Pb and serum calcium (high Pb, r = −0.78, p < 0.001) or calcium<br />

intake high Pb, (r = −0.82, p < 0.001) in all three Pb strata. Serum<br />

25-OH-D was significantly positively correlated with vitamin D<br />

intake, but not with blood Pb.<br />

Dietary calcium intake (mg/day) mean (SE):<br />

Low Pb: 770 (20)<br />

Moderate Pb: 760 (28)<br />

High Pb: 610 (20)


AX6-242<br />

Table AX6-9.5 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Siegel et al. (1989)<br />

Connecticut<br />

1987<br />

Koo et al. (1991)<br />

Ohio<br />

NR<br />

Design: cross-sectional<br />

Subjects: children (n = 68, 32 female), ages<br />

11 mo to 7 yr<br />

Outcome measures: serum FT4, TT4<br />

Analysis: linear regression<br />

Design: longitudinal (subset <strong>of</strong> prospective)<br />

Subjects: children (n = 105, 56 females), age<br />

21, 27, 33 mo<br />

Outcome measures: serum calcium<br />

magnesium, phosphorus, PTH, CAL, 25-OH-<br />

D, 1,25-OH-D, and bone mineral content<br />

Analysis: structural equation modeling<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

25 (2–77)<br />

Blood Pb (µg/dL)<br />

geometric mean<br />

(GSD, range):<br />

Lifetime mean, based on<br />

quarterly measurements:<br />

9.74 (1.44, 4.8–23.6)<br />

Concurrent:<br />

15.01 (1.52, 6–44)<br />

Maximum observed:<br />

18.53 (1.53, 6–63)<br />

No significant association between blood Pb concentration and<br />

thyroid hormone outcomes. Linear regression parameters:<br />

FT4: ∀ = 1.55 (SE 0.05), ∃ = 0.0024 (SE 0.0016), r 2 = 0.03,<br />

p = 0.13<br />

TT4: ∀ = 8.960 (SE 0.39), ∃ = 0.0210 (SE 0.0127), r 2 = 0.04,<br />

p = 0.10<br />

Significant association between increasing blood Pb (ln-trans<strong>for</strong>med)<br />

and covariate-adjusted decreasing serum phosphorus<br />

(∀ = 1.83, ∃ = −0.091). No other covariate-adjusted outcomes were<br />

significantly associated with blood Pb.<br />

Covariates retained: age, sex, race, and sampling season.<br />

Dietary calcium intake (mg/day)<br />

#600: n = 4 (4%)<br />

600–1200: n = 58 (55%)<br />

>1200: n = 43 (41%)


AX6-243<br />

Table AX6-9.6. Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States<br />

Cullen et al. (1984)<br />

Connecticut<br />

1979<br />

NR<br />

Robins et al. (1983<br />

Connecticut<br />

NR<br />

Braunstein et al.<br />

(1978)<br />

Cali<strong>for</strong>nia<br />

NR<br />

Refowitz (1984)<br />

NR<br />

Design: clinical case study<br />

Subjects: adult males with neurological<br />

symptoms <strong>of</strong> Pb poisoning<br />

Outcome measures: serum, FSH, LH, PRL,<br />

TES<br />

Analysis: clinical outcomes in terms <strong>of</strong><br />

abnormal values<br />

Design: cross-sectional<br />

Subjects: adult male brass foundry workers<br />

(n = 47), age range 20–64 yr<br />

Outcome measures: FT4<br />

Analysis: simple linear regression with<br />

stratification by age and race.<br />

Design: clinical<br />

Subjects: adult male secondary Pb smelter<br />

(n = 12), mean age 38 yr, reference group,<br />

(n = 9), mean age 29 yr<br />

Outcome measures: serum EST, FSH, LH,<br />

TES, HCG-stimulated EST and TES, GnRHstimulated<br />

serum FSH and LH<br />

Analysis: comparisons <strong>of</strong> outcome measures<br />

between patients symptomatic <strong>for</strong> Pb<br />

poisoning, Pb-exposed patients not<br />

symptomatic, reference group<br />

Design: cross-sectional survey<br />

Subjects: secondary copper smelter workers<br />

(n = 58)<br />

Outcome measures: FT4, TT4<br />

Analysis: linear regression<br />

Blood Pb (µg/dL) range:<br />

66–139<br />

Blood Pb (µg/dL) range:<br />

16–127<br />

Blood Pb (µg/dL) mean (SD):<br />

Symptomatic (n = 9):<br />

Time <strong>of</strong> test: 38.7 (3.0)<br />

Highest: 88.2 (4.0)<br />

Asymptomatic (n = 4):<br />

Time <strong>of</strong> test: 29.0 (5.0)<br />

Highest: 80.0 (0.0)<br />

Reference: 16.1 (1.7)<br />

Blood Pb (µg/dL) range:<br />

5–60<br />

Five subjects with defects in spermatogenesis (including<br />

azospermia), with no change in basal serum FSH, LH,<br />

PRL, and TES.<br />

Significant association between increasing blood Pb<br />

concentration and decreasing FT4 (∀ = 1.22,<br />

∃ = −0.0042 [95% CI: −0.0002, −0.0082], r 2 = 0.085,<br />

p = 0.048). Significant interaction between race (black,<br />

white) and blood Pb.<br />

When stratified by race:<br />

Black: ∀ = 1.13, ∃ = −0.0051 (95% CI: 0.0007,<br />

−0.0095), r 2 = 0.21, p = 0.03<br />

White: r 2 = 0.05, p = 0.27<br />

Strength <strong>of</strong> association not changed by including age in<br />

the regression model.<br />

Statistically significant (p < 0.05) lower basal serum<br />

TES, higher TES response to HCG, and significantly<br />

reduced LH response to GnRH in workers symptomatic<br />

<strong>for</strong> Pb poisoning (including EDTA-provoked urinary Pb<br />

>500 µg/24 hr).<br />

No significant association between blood Pb and<br />

hormone levels:<br />

FT4: ∀ = 2.32, ∃ = −0.0067 (95% CI: −0.18, 0.0043)<br />

TT4: ∀ = NR, ∃ = −0.28 (95% CI: −0.059, 0.0002)<br />

No significant association when ratified by race (black,<br />

white)


AX6-244<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada<br />

Alexander et al. (1998,<br />

1996a)<br />

British Columbia<br />

1993<br />

Schumacher et al.<br />

(1998)<br />

British Columbia<br />

1993<br />

Europe<br />

Gennart et al. (1992)<br />

Belgium<br />

NR<br />

Design: cross-sectional<br />

Subjects: adult male primary smelter workers<br />

(n = 152), mean age 40 yr<br />

Outcome measures: serum FSH, LH, TES<br />

Analysis: multivariate linear regression<br />

Design: cross-sectional<br />

Subjects: adult male smelter workers<br />

(n = 151) mean age 40 yr (SD 7.2)<br />

Outcome measures: serum FT4, TT4, TSH<br />

Analysis: linear regression, ANOVA<br />

Design: cross sectional cohort<br />

Subjects: adult battery manufacture workers<br />

(n = 98), mean age 37.7 yr (SD 8.3, range 22–<br />

55); reference worker group (n = 85), mean<br />

age 38.8 yr (SD 8.7, range 22–55)<br />

Outcome measures: serum TT3, FT4, TT4,<br />

TSH, FSH, LH<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

Blood Pb (µg/dL) range<br />

(n = 81): 22.8 (5–58)<br />

Semen Pb (µg/dL) range:<br />

1.9 (0.1–17.6)<br />

Blood Pb (µg/dL) mean:<br />

24.1 (n = 151)<br />


AX6-245<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Assennato et al. (1987)<br />

Italy<br />

NR<br />

Govoni et al. (1987)<br />

Italy<br />

NR<br />

Rodamilans et al.<br />

(1988)<br />

Spain<br />

NR<br />

Design: cross-sectional<br />

Subjects: adult male battery manufacture<br />

workers (n = 39), mean age 41 yr (SD 10);<br />

reference cement plant workers (n = 18), mean<br />

age 40 yr (SD 10)<br />

Outcome measures: serum FSH, LH, PRL,<br />

TES; urinary 17-ketosteroids<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures between Pb and reference groups<br />

Design: cross-sectional<br />

Subjects: adult male pewter manufacture<br />

workers (n = 78), mean age 35 yr (SD 19,<br />

range 19–52)<br />

Outcome measures: serum PRL<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures between blood Pb and ZPP strata<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb smelter workers<br />

(n = 23), age range 21–44 yr; reference group<br />

(n = 20), age range 20–60 yr<br />

Outcome measures: serum FSH, LH, TES,<br />

FTES, SHBG<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between exposure duration strata<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 61 (20)<br />

Reference: 18 (5)<br />

Urinary Pb (µg/L) mean<br />

(SD):<br />

Pb: 79 (37)<br />

Reference: 18 (8)<br />

Blood Pb (µg/dL) mean<br />

(SD)/blood ZPP (µg/dL)<br />

mean (SD):<br />

A (n = 22):<br />

28.2 (7.1)/24.4 (8.7)<br />

B (n = 33):<br />

60/3 (19.3)/131 (107)<br />

C (n = 13):<br />

33.1 (6.7)/77.0 (42.2)<br />

D (n = 8):<br />

49.1 (4.2)/34.0 (4.8)<br />

Blood Pb (µg/dL) mean<br />

(SD)<br />

Pb 5 yr (n = 10): 76 (11)<br />

Reference (n = 20): 17.2<br />

(13)<br />

No significant association (p > 0.05) between blood Pb and<br />

hormone levels.<br />

Significantly (p < 0.02) higher serum PRL in high ZPP strata (B and<br />

C, compared to low ZPP strata A).<br />

Serum TES (p = 0.01) and FTES (p = 0.001) significantly lower and<br />

SHBG significantly higher (p < 0.025) in >5-yr exposure group<br />

compared to reference group; serum LH was significantly (p < 0.01)<br />

higher in all exposure groups compared to reference group.


AX6-246<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Erfurth et al. (2001)<br />

Sweden<br />

NR<br />

Gustafson et al. (1989)<br />

Sweden<br />

NR<br />

Campbell et al. (1985)<br />

UK<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male active secondary smelter<br />

workers (n = 62), mean age 43 yr (range 21–<br />

78) reference worker group (n = 26), mean<br />

age 43 yr (range 23–66)<br />

Outcome measures: serum FT3, FT4, TSH,<br />

TES, SHBG; TRH-stimulated serum TSH;<br />

GnRH-stimulated serum FSH, LH, and PRL<br />

Analysis: nonparametric comparison <strong>of</strong><br />

outcome measures between Pb workers and<br />

reference group; multivariate linear regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male secondary smelter<br />

workers (n = 21) mean age 36.0 yr (SD 10.4);<br />

individually matched <strong>for</strong> age, sex, and work<br />

shift (n = 21)<br />

Outcome measures: serum FTES, TTES;<br />

FSH, LH, PRL, COR, TSH, TT3, TT4<br />

Analysis: nonparametric comparison <strong>of</strong><br />

outcome measures between Pb workers and<br />

reference group, correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult male welders (n = 25);<br />

reference subjects (n = 8) (ages NR)<br />

Outcome measures: plasma ACE, AI, PRA,<br />

plasma ALD<br />

Analysis: linear regression, nonlinear least<br />

squares<br />

Blood Pb (µg/dL) median (range):<br />

Pb: 31.1 (8.3–93.2)<br />

Reference: 4.1 (0.8–6.2)<br />

Plasma Pb (µg/dL) median (range):<br />

Pb: 31.1 (8.3–93.2)<br />

Reference: 4.1 (0.8–6.2)<br />

Urine Pb (µg/g creatinine) median (range):<br />

Pb: 19.6 (3.1–80.6)<br />

Reference: 4.1 (2.4–7.3)<br />

Bone (finger) Pb (µg/g) median (range):<br />

Pb: 25 (−13 to 99)<br />

Reference: 2 (−21 to 14)<br />

Blood Pb (µg/dL) mean (SE):<br />

Pb: 39.4 (2.1)<br />

Reference: 5.0 (0.2)<br />

Blood Pb (µg/dL) mean (SD, range): 35.6<br />

(15.3, 8–62)<br />

Basal hormone levels in workers not different from<br />

reference group (p ∃ 0.05); age-adjusted basal<br />

hormone levels not associated with plasma Pb, blood<br />

Pb, urine Pb, or bone Pb. In an age-matched subset<br />

<strong>of</strong> the cohorts (n = 9 Pb workers, n = 11 reference),<br />

median GnRH-stimulated serum FSH was<br />

significantly (p = 0.014) lower (77 IU/L Η hr) in Pb<br />

workers than in reference group (162 IU/L Η hr).<br />

No association between stimulated TSH, LH, FSH or<br />

PRL and Pb measures.<br />

Significantly higher TT4 (p < 0.02) and lower serum<br />

FSH (p = 0.009) in Pb workers compared to<br />

reference group. When restricted to the age range<br />


AX6-247<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Europe (cont’d)<br />

Chalkley et al. (1998)<br />

UK<br />

1979–1984<br />

Mason et al. (1990)<br />

UK<br />

NR<br />

McGregor and Mason,<br />

(1990)<br />

UK<br />

NR<br />

Design: cross-sectional<br />

Subjects: adult male primary metal<br />

(cadmium, Pb, zinc) workers (n = 19), ages<br />

NR<br />

Outcome measures: blood calcium, serum 25-<br />

OH-D, 1,25-OH-D, 24,25-OH-D<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

(ANOVA) in group stratified by blood Pb and<br />

urinary cadmium<br />

Design: cross-sectional<br />

Subjects: adult male Pb workers (n = 63), age<br />

range 21–63 yr; reference male subjects<br />

(n = 75), age range 22–64 yr<br />

Outcome measures: serum calcium<br />

phosphate, PTH, 1,25-OH-D<br />

Analysis: comparison <strong>of</strong> al outcome measures<br />

between Pb workers and reference group,<br />

multivariate regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb workers (n = 90),<br />

mean age (31.5 yr (SD 11.9); reference<br />

workers (n = 86), mean age 40.6 yr (SD 11.8)<br />

Outcome measures: serum FSH, LH, TES,<br />

SHBG<br />

Analysis: comparison <strong>of</strong> outcome means<br />

between Pb workers and reference groups,<br />

multivariate regression, correlation<br />

Blood Pb (µg/dL) mean<br />

(SD, range): 47 (21–76)<br />

Blood Pb (µg/dL) range:<br />

Pb (15–94)<br />

Reference: NR<br />

Tibia Pb (µg/g)<br />

Pb: 0–93<br />

Reference: NR<br />

Blood Pb (µg/dL) range:<br />

Pb: 17–77<br />

Reference: 40 µg/dL)/high blood<br />

cadmium (>0.9 µg/L)/high urine cadmium >3.1 µg/L) stratum<br />

compared to low blood Pb (0.9 µg/L)/high urine cadmium >3.1 µg/L) stratum. Serum 24,25-<br />

OH-D levels decreased with increasing urinary cadmium (p = NR)<br />

Significantly higher (p < 0.025) prevalence <strong>of</strong> elevated 1,25-OH-D<br />

(>2 SD <strong>of</strong> reference mean) in Pb workers (8/63, 13%) compared to<br />

reference group (1/75, 1.3%). Serum levels <strong>of</strong> 1,25-OH-D<br />

significantly (p < 0.05) higher in Pb workers compared to reference<br />

group.<br />

After stratification <strong>of</strong> Pb workers into exposure categories (high:<br />

blood Pb ∃40 µg/dL and bone Pb ∃40 µg/g, low: blood Pb<br />

#40 µg/dL and bone Pb #40 µg/g), serum 1,25-OH-D levels were<br />

significantly (p < 0.01) higher in the high Pb group.<br />

Increasing blood Pb was significantly (p = NR) associated with<br />

increasing 1,25-OH-D levels (r 2 = 0.206; with age and bone Pb<br />

included, r 2 = 0.218). After excluding 12 subjects whose blood Pb<br />

concentrations >60 µg/dL, r 2 = 0.162 (p = 0.26).<br />

Age-adjusted serum FSH was significantly (p = 0.004) higher in Pb<br />

workers compared to reference group.<br />

Increasing serum FSH significantly (p = NR) associated with blood<br />

Pb and age. Increasing serum LH significantly associated with<br />

increasing exposure duration (not blood Pb or age).<br />

No significant association between serum TES or SHBG and blood<br />

Pb or exposure duration.<br />

No significant difference in prevalence <strong>of</strong> abnormal hormone levels<br />

between groups.


AX6-248<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Latin America<br />

L∴pez et al. (2000)<br />

Argentina<br />

NR<br />

Roses et al. (1989)<br />

Brazil<br />

NR<br />

Asia<br />

Dursun and Tutus<br />

(1999)<br />

Turkey<br />

NR<br />

Design: cross sectional<br />

Subjects: adult male battery manufacture<br />

workers (n = 75), age range 21–56 yr;<br />

reference group (n = 62), age NR<br />

Outcome measures: serum TT3, FT4, TT4,<br />

TSH<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group,<br />

correlation<br />

Design: adult male Pb workers (n = 70), age<br />

range 20–53 yr; reference group (n = 58), age<br />

range 25–37 yr.<br />

Outcome measures: serum PRL<br />

Analysis: comparison <strong>of</strong> outcome measure<br />

between Pb workers and reference group,<br />

linear regression<br />

Design: cross-sectional<br />

Subjects: adult metal powder manufacture<br />

workers (n = 27) mean age 41.1 yr (SD 5.45,<br />

range 25–50); reference group (n = 30), mean<br />

age 42 yr (SD 3.42, range 28–49)<br />

Outcome measures: serum FT4, TT4, FT3,<br />

TT3, TSH<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures between Pb and reference groups,<br />

simple and multivariate linear regression<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Pb: 50.9 (23.3, 8–98)<br />

Reference: 19.1 (7.1, 4–39)<br />

Blood Pb (µg/dL) range:<br />

Pb: 9–86<br />

Reference: 8–28<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Pb: 17.1 (9.0, 6–36)<br />

Reference: 2.4 (0.1, 1–4)<br />

Significantly higher serum FT4 (p < 0.01) and TT4 (p < 0.05) in Pb<br />

workers compared to reference group. Significant positive<br />

correlation between blood Pb and serum TT3 (p < 0.05), FT4<br />

(p < 0.01), TT4 (p < 0.05), and TSH (p < 0.05), <strong>for</strong> blood Pb range<br />

8–50 µg/dL; and <strong>for</strong> TSH (p < 0.05) <strong>for</strong> blood Pb range 8–<br />

26 µg/dL.<br />

Serum RL levels in Pb workers and reference group not<br />

significantly different (p = NR). Correlation between serum PRL<br />

and blood Pb (r = 0.57, p = NR).<br />

Significantly (p < 0.0001) higher mean TT4, FT4, and FT3 in Pb<br />

workers compared to reference group.<br />

Significant association between TT4, age (∃ = 0.23, p < 0.006), and<br />

exposure duration (∃ = −0.20, p > 0.01), but not blood Pb (∃ = 0.00,<br />

NR) in linear regression model that included age, blood Pb, and<br />

exposure duration (∀ = 2.76, r 2 = 0.3, p = 0.03).


AX6-249<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Kristal-Boneh et al.<br />

(1998)<br />

Israel<br />

NR<br />

Horiguchi et al. (1987)<br />

Japan<br />

NR<br />

Ng et al. (1991)<br />

China<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery<br />

manufacture/recycling workers (n = 56), mean<br />

age 43.4 yr (SD 11.2); reference workers<br />

(n = 90), mean age 41.5 yr (SD 9.3)<br />

Outcome measures: serum calcium,<br />

magnesium, phosphorus, PTH, 25-OH-D,<br />

1,25-OH-D<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures between Pb workers and reference<br />

group, multivariate linear regression<br />

Design: cross-sectional<br />

Subjects: adult secondary Pb refinery (n = 60,<br />

8 females), mean age 49 yr (range 15–69)<br />

Outcome measures: serum TT3, TT4, TSH<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

(method NR), between job categories,<br />

correlation<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 122), mean age 32.6 (SD 8,2,<br />

range 17–54); reference group (n = 49), mean<br />

age 43.4 yr (SD 13.4, range 18–74)<br />

Outcome measures: serum FSH, LH, PRL,<br />

TES<br />

Analysis: multivariate linear regression<br />

ANCOVA<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 42.6 (14.5, 20–77)<br />

Reference: 4.5 (2.6, 1.4–<br />

19)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Male: 31.9 (20.4)<br />

Female: 13.5 (9.5)<br />

Urine Pb (µg/L) mean (SD):<br />

Male: 59.3 (76.3)<br />

Female: 26.0 (19.7)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 35.2 (13.2, 9.6–77.4)<br />

Reference: 8.3 (2.8, 2.6–<br />

14.8)<br />

Serum 1,25-OH-D (p = 0.0001) and PTH (p = 0.042) were<br />

significantly higher in Pb workers compared to reference group<br />

Increasing blood Pb concentration (ln-trans<strong>for</strong>med) was<br />

significantly associated with covariate-adjusted increasing serum<br />

PTH and 1,25-OH-D levels:<br />

PTH: ∃ = 4.8 (95% CI: 0.8, 8.8), r 2 = 0.12<br />

1,25-OH-D: ∃ = 4.8 (95% CI: 2.7, 6.9), r 2 = 0.10<br />

Occupational Pb exposure (yes) significantly associated with<br />

increasing PTH and 1,25-OH-D levels.<br />

Covariates retained: age, alcohol consumption, smoking; calcium,<br />

magnesium, and calorie intake:<br />

PTH: ∃ = 7.81 (95% CI: 3.7, 11.5)<br />

1,25-OH-D: ∃ = 12.3 (95% CI: 3.84, 20.8)<br />

No significant differences (p = NR) between hormone levels in job<br />

Pb categories: mean blood Pb (µg/dL, SD): 17.9 (10.7), 25.6<br />

(15.4), 49.9 (18.7). No significant correlations (p = NR) between<br />

hormone levels and blood or urine Pb levels.<br />

When cohorts were stratified by age serum FSH and LH were<br />

significantly (p < 0.02) higher in Pb workers


AX6-250<br />

Table AX6-9.6 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Endocrine System in Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Zheng et al. (2001)<br />

China<br />

NR<br />

Singh et al. (2000)<br />

India<br />

NR<br />

Africa<br />

Tuppurainen et al.<br />

(1988)<br />

Kenya<br />

1984<br />

Design: retrospective cross-sectional<br />

Subjects: adult hospital patients (n = 82, 32<br />

females) mean age 49.6 yr (SD 18.7)<br />

Outcome measures: serum and CSF TTR,<br />

TT4<br />

Analysis: simple and multivariate linear<br />

regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male petrol pump attendants<br />

(n = 58), mean age 31.7 yr (SD 10.6);<br />

reference group (n = 35), mean age 28.9 yr<br />

(SD 4.20)<br />

Outcome measures: serum TT3, TT4, TSH<br />

Analysis: parametric comparison <strong>of</strong> outcome<br />

measures between Pb workers and reference<br />

group, stratified by blood Pb or exposure<br />

duration<br />

Design: cross-sectional<br />

Subjects: adult male battery manufacture<br />

workers (n = 176), mean age 34.1 yr<br />

(SD 8.1, range 21–54)<br />

Outcome measures: serum TT3, FT4,<br />

TT4, TSH<br />

Analysis: multivariate linear regression<br />

and correlation<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

All: 14.9 (8.3)<br />

Female: 14.2 (8.76)<br />

Male: 15.4 (8.07)<br />

Blood Pb (µg/dL) mean<br />

(SD):<br />

Pb: 51.6 (9.3)<br />

Reference: 9.5 (8.7)<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

55.9 (23.8, 14.5–133.6)<br />

No significant association between blood Pb and serum TTR<br />

(r = −0.114, p = 0.307), TT4 (r = −0.160, p = 0.152).<br />

Significant association between age-adjusted CSF Pb and CSF TTR<br />

(r = −030, p = 0.023).<br />

No significant association between CSF Pb and CSF TT4<br />

(r = −0.22, p = 0.090).<br />

Serum TSH significantly higher (p < 0.01) in Pb workers compared<br />

to reference group, significantly higher in high blood Pb category<br />

(#70 µg/dL, mean 54.5 µg/dL) compared to low worker group<br />

#41 µg/dL, mean 31.3 µg/dL). Serum TSH significantly higher in<br />

Pb workers who were exposed <strong>for</strong> #60 mo, compared to workers<br />

exposed <strong>for</strong> >60 mo.<br />

Increasing exposure duration significantly associated with<br />

decreasing FT4 (r 2 = 0.071, p = 0.001) and TT4 (r 2 = 0.059,<br />

p = 0.021); regression not improved by including age or blood Pb.<br />

Strength <strong>of</strong> association greater when restricted to workers who had<br />

an exposure duration >7.6 yrs: FT4: r 2 = 0.33, p < 0.002; TT4:<br />

r 2 = 0.21, p < 0.001.<br />

No significant association between blood Pb and hormone levels.


AX6-251<br />

Table AX6-9.7. Effects <strong>of</strong> <strong>Lead</strong> on the Hepatic System in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Children<br />

United States<br />

Saenger et al. (1984)<br />

New York<br />

NR<br />

Adults<br />

Asia<br />

Al-Neamy et al. (2001)<br />

United Arab Emirates<br />

1999<br />

Design: clinical cases<br />

Subjects: children (n = 26) ages 2–9 yr; agematched<br />

reference group (n = NR)<br />

Outcome measures: urinary cortisol and 6∃-<br />

OH-cortisol (CYP3A metabolite <strong>of</strong> cortisol)<br />

Analysis: comparison <strong>of</strong> outcome measure<br />

between children who qualified <strong>for</strong> EDTA<br />

treatment (EDTA provocation >500 µg/24<br />

hr)<br />

Design: cross-sectional cohort<br />

Subjects: adult male (n = 100) workers (e.g.,<br />

gas pump attendants, garage workers,<br />

printing workers, construction workers),<br />

mean age 34.6 yr (SD 8.0); reference group<br />

(n = 100) matched with Pb workers <strong>for</strong> age,<br />

sex, nationality.<br />

Outcome measures: serum protein, albumin,<br />

ALT, AP, AST, BUN, (GT, LDH<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

Blood Pb (µg/dL) mean<br />

(SE, range):<br />

Chelated: 46 (2, 33–60)<br />

Not chelated:<br />

42 (3, 32–60)<br />

Urinary Pb (µg/24 hr) mean<br />

(SE, range), EDTAprovocation:<br />

Chelated: 991 (132, 602–<br />

2247)<br />

Not chelated: 298 (32,<br />

169–476)<br />

Blood Pb (µg/dL) mean<br />

(SD): Pb: 77.5 (42.8)<br />

Reference: 19.8 (12.3)<br />

Significantly lower (~45% lower) urinary excretion <strong>of</strong> 6∃-OHcortisol<br />

(p = 0.001) and urinary 6∃-OH-cortisol: cortisol ratio<br />

(p < 0.001) in children who qualified <strong>for</strong> chelation than in children<br />

who did not qualify and significantly lower than age-matched<br />

reference group. Urinary 6∃-OH-cortisol: cortisol ratio was<br />

significantly correlated with blood Pb (r = −0.514, p < 0.001),<br />

urinary Pb, and EDTA provocation urinary Pb (r = −0.593,<br />

p < 0.001).<br />

Significantly higher serum AP (p = 0.012) and LDH (p = 0.029) in<br />

Pb workers compared to reference group (values within normal<br />

range).


AX6-252<br />

Table AX6-9.7 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Hepatic System in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Hsiao et al. (2001)<br />

China<br />

1989–1999<br />

Satarug et al. (2004)<br />

Thailand<br />

NR<br />

Design: longitudinal<br />

Subjects: adult battery manufacture workers<br />

(n = 30, 13 females), mean age 38.3 yr<br />

Outcome measures: serum ALT<br />

Analysis: GEE <strong>for</strong> repeated measures<br />

(models: linear correlation, threshold<br />

change, synchronous change, lag change);<br />

logistic regression<br />

Design: cross-sectional<br />

Subjects: adults from general population<br />

(n = 118, 65 female), age range, 21–57 yr<br />

Outcome measures: coumarin-induced<br />

urinary 7-OH-coumarin (marker <strong>for</strong><br />

CYP2A6 activity)<br />

Analysis: multivariate linear regression<br />

Blood Pb (µg/dL) mean:<br />

1989: 60 (~25–100)<br />

1999: 30 (~10–60)<br />

Urinary Pb (µg/g<br />

creatinine) mean<br />

(SD, range):<br />

Males: 1.3 (1.8, 0.1–12)<br />

Females: 2.4 (1.1, 0.6–6.8)<br />

Serum Pb (µg/L) mean<br />

(SD, range):<br />

Males: 4.2 (5.4, 1–28)<br />

Females: 3.0 (2.2, 1–12)<br />

No association between blood Pb and ALT.<br />

Odds ratios (95% CI):<br />

Synchronous change model: 1.25 (0.69, 2.25)<br />

Lag change: 1.76 (0.76, 4.07)<br />

Significant association between increasing urinary Pb and decreasing<br />

covariate-adjusted urinary 7-OH-coumarin (∃ = −0.29, p = 0.003) in<br />

males, but not in females. Covariates retained: age and zinc<br />

excretion. Significant association in opposite direction between<br />

urinary cadmium and urinary 7-OH-coumarin (∃ = 0.38, p = 0.006).


AX6-253<br />

Table AX6-9.8. Effects <strong>of</strong> <strong>Lead</strong> on the Gastrointestinal System<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Canada<br />

Holness and Nethercott<br />

(1988)<br />

Ontario<br />

1982–1984<br />

Caribbean<br />

Matte et al. (1989)<br />

Jamaica<br />

1987<br />

Asia<br />

Bercovitz and Laufer<br />

(1991)<br />

Israel<br />

NR<br />

Design: longitudinal<br />

Subjects: adult male demolition workers<br />

(n = 119), age NR<br />

Outcome measures: prevalence <strong>of</strong> symptoms<br />

Analysis: comparison <strong>of</strong> prevalence <strong>of</strong><br />

symptoms (questionnaire) stratified by job<br />

phase or blood Pb<br />

Design: survey<br />

Subjects: battery manufacture/repair<br />

workers (n = 63), mean age ~30 yr<br />

(range 11–47)<br />

Outcome measures: prevalence <strong>of</strong> symptoms<br />

Analysis: comparison <strong>of</strong> GI symptoms<br />

(questionnaire) between blood Pb strata<br />

Design: cross-sectional<br />

Subjects: health individuals (n = 12), peptic<br />

ulcer patients (n = 11), and individuals with<br />

heart disease (n = 11) with environmental<br />

exposure<br />

Analysis: one-way ANOVA used to<br />

compare tooth Pb concentrations in the three<br />

groups<br />

Blood Pb (µg/dL) mean<br />

(range):<br />

Phase 1: 59 (15–99)<br />

Phase 2: 30<br />

Phase 3: 19<br />

Phase 4: 17<br />

Blood Pb (µg/dL)<br />

geometric mean site range:<br />

40–64<br />

Blood Pb distribution:<br />

>60: 60%<br />


AX6-254<br />

Table AX6-9.8 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on the Gastrointestinal System<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Asia (cont’d)<br />

Lee et al. (2000)<br />

Korea<br />

NR<br />

Africa<br />

Awad el Karim et al.<br />

(1986)<br />

Sudan<br />

NR<br />

Design: cross-sectional cohort<br />

Subjects: adult male Pb workers (n = 95;<br />

secondary smelter, PVC-stabilizer<br />

manufacture, battery manufacture); mean age<br />

42.8 yr (SD 9.3, range 19–64); reference<br />

group (n = 13), mean age 35.1 yr (SD 9.9,<br />

range 22–54)<br />

Outcome measures: prevalence <strong>of</strong> GI<br />

symptoms (self-administered questionnaire)<br />

Analysis: multivariate logistic regression<br />

Design: cross-sectional cohort<br />

Subjects: adult male battery manufacture<br />

workers (n = 92), mean age 31.1 yr (SD 8.2);<br />

reference group (n = 40), mean age 33.7 yr<br />

(SD 9.7)<br />

Outcome measures: clinical evaluation<br />

Analysis: comparison <strong>of</strong> prevalence <strong>of</strong><br />

symptoms <strong>of</strong> Pb poisoning between Pb<br />

workers and reference group<br />

Blood Pb (µg/dL) mean<br />

(SD, range):<br />

Pb: 44.6 (12.6, 21.4–78.4)<br />

Reference:<br />

5.9 (1.2, 4.0–7.2)<br />

Blood Pb distribution <strong>for</strong><br />

Pb workers<br />

>80: 23%<br />

40–80: 72%<br />


AX6-255<br />

Table AX6-9.9. Effects <strong>of</strong> <strong>Lead</strong> on Bone and Teeth in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Children<br />

United States<br />

Moss et al. (1999)<br />

U.S.<br />

1988–1994<br />

Design: cross-sectional national survey<br />

(NHANES <strong>II</strong>I)<br />

Subjects: general population (n = 24,901),<br />

ages 2–5 yr (n = 3,547), 6–11 yr (n = 2,894),<br />

∃12 yr (18,460)<br />

Outcome measures: number <strong>of</strong> caries (dfs,<br />

DFS, DMFS)<br />

Analysis: multivariate linear regression and<br />

logistic regression<br />

Blood Pb (:g/dL) geometric<br />

mean (SE):<br />

2–5 yr: 2.90 (0.12)<br />

6–11 yr: 2.07 (0.08)<br />

∃12 yr: 2.49 (0.06)<br />

Increasing blood Pb concentration (log-trans<strong>for</strong>med) significantly<br />

associated with covariate adjusted increases in dfs:<br />

2–5 yr: ∃ = 1.78 (SE 0.59), p = 0.004<br />

6–11 yr: ∃ = 1.42 (SE 0.51), p = 0.007<br />

Increases in DFS:<br />

6–11 yr: ∃ = 0.48 (SE 0.22), p = 0.03<br />

∃12 yr: ∃ = 2.50 (SE 0.69), p < 0.001<br />

Increases in DMFS:<br />

∃12 yr: ∃ = 5.48 (SE 1.44), p = 0.01<br />

Odds ratio (OR) <strong>for</strong> caries (∃1 DMFS, ages 5–17 yr) and population<br />

attributable risk (PAR) in association with 2nd or 3rd blood Pb<br />

tertiles, compared to 1st tertile were:<br />

1st tertile (#1.66 :g/dL)<br />

2nd tertile (1.66–3.52 :g/dL): OR = 1.36 (95% CI: 1.01, 2.83);<br />

PAR = 9.6%<br />

3rd tertile (>3.52 :g/dL): OR = 1.66 (95% CI: 1.12, 2.48);<br />

PAR = 13.5%<br />

For an increase <strong>of</strong> blood Pb <strong>of</strong> 5 :g/dL, OR = 1.8 (95% CI: 1.3, 2.5)<br />

Covariates retained were age, gender, race/ethnicity, poverty income<br />

ratio, exposure to cigarette smoke, geographic region, educational<br />

level <strong>of</strong> head <strong>of</strong> household, carbohydrate and calcium intakes, and<br />

dental visits.


AX6-256<br />

Table AX6-9.9 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Bone and Teeth in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

United States (cont’d)<br />

Schwartz et al. (1986)<br />

U.S.<br />

1976–1980<br />

Gemmel et al. (2002)<br />

Boston/Cambridge, MA<br />

NR<br />

Campbell et al. (2000)<br />

New York<br />

1995–1997<br />

Design: cross-sectional national survey<br />

(NHANES <strong>II</strong>)<br />

Subjects: ages


AX6-257<br />

Table AX6-9.9 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Bone and Teeth in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Adults<br />

United States<br />

Dye et al. (2002)<br />

U.S.<br />

1988–1994<br />

Europe<br />

Tvinnereim et al.<br />

(2000)<br />

Norway<br />

1990–1994<br />

Design: cross-sectional national survey<br />

(NHANES <strong>II</strong>I)<br />

Subjects: adults in general population<br />

(n = 10,033; 5,255 females), ages 20–69 yr<br />

Outcome measures: symptoms <strong>of</strong><br />

periodontal bone loss (attachment loss,<br />

periodontal pocket depth)<br />

Analysis: multivariate linear regression<br />

Design: cross-sectional<br />

Subjects: 1,271 teeth samples collected by<br />

dentists in all 19 counties in Norway<br />

Analysis: Student’s t-test comparing metal<br />

concentrations in teeth with caries, roots, and<br />

in different tooth groups<br />

Blood Pb (:g/dL) geometric<br />

mean (SE, range):<br />

2.5 (0.08) (2.36% > 10)<br />

Tooth Pb (:g/g tooth)<br />

geometric mean (SD,<br />

range):<br />

1.16 (1.72, 0.12–18.76)<br />

Increasing blood Pb (log-trans<strong>for</strong>med) was significantly associated<br />

with increasing prevalence <strong>of</strong> covariate-adjusted dental furcation<br />

(∃ = 0.13 [SE 0.05], p = 0.005). Covariates retained: age, sex,<br />

race/ethnicity, education, smoking, and age <strong>of</strong> home. Smoking<br />

status interaction was significant when included in the model as an<br />

interaction term (∃ = 0.10 [SE 0.05], p = 0.034). When stratified by<br />

smoking status, association between dental furcation and blood Pb<br />

was significant <strong>for</strong> current smokers (∃ = 0.21 [SE 0.07], p = 0.004)<br />

and <strong>for</strong>mer smokers (∃ = 0.17 [SE 0.07], p = 0.015), but not <strong>for</strong><br />

nonsmokers (∃ = −0.02 [SE 0.07], p = 0.747).<br />

Also examined mercury, cadmium, and zinc. All tooth groups had<br />

higher Pb concentrations in carious than in non-carious teeth. The<br />

geometric mean Pb concentration in carious teeth was 1.36 :g/g<br />

compared to 1.10 :g/g (p = 0.001).


AX6-258<br />

Table AX6-9.10. Effects <strong>of</strong> <strong>Lead</strong> on Ocular Health in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Children<br />

Latin America<br />

Rothenberg et al.<br />

(2002b)<br />

Mexico<br />

1987–1997<br />

Adults<br />

United States<br />

Schaumberg et al.<br />

(2004)<br />

Massachusetts<br />

1991–2002<br />

Design = longitudinal (subset <strong>of</strong> prospective)<br />

Subjects: children (n = 45, 24 female), ages<br />

7–10 yr<br />

Outcome measures: ERG<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between blood Pb tertiles (ANOVA <strong>for</strong><br />

repeated measures)<br />

Design = longitudinal (subset <strong>of</strong> Normative<br />

Aging Study)<br />

Subjects: adult male (n = 642), mean age<br />

69 yr (range 60–93)<br />

Outcome measures: cataract diagnosis<br />

Analysis: multivariate logistic regression,<br />

odds ratio (vs. 1st quintile)<br />

Blood Pb (:g/dL) median<br />

(range) at 85–124 mo:<br />

1st tertile: 4.0 (2.0–4.5)<br />

2nd tertile: 6.0 (5.0–6.5)<br />

3rd tertile: 7.5 (7.0–16.0)<br />

Blood Pb (:g/dL) median<br />

(range), maternal at 12 wk<br />

<strong>of</strong> gestation:<br />

1st tertile: 4.0 (2.0–5.5)<br />

2nd tertile: 8.5 (6.0–10.0)<br />

3rd tertile: 14.0 (10.5–<br />

32.5)<br />

Blood Pb (:g/dL) median<br />

(range):<br />

5 (0–35)<br />

Bone Pb (:g/g) median<br />

(range):<br />

Patella : 29 (0–165)<br />

Tibia: 20 (0–126)<br />

Significant association between increasing maternal blood Pb at<br />

12 wk <strong>of</strong> gestation and increasing ERG a-wave (p = 0.025) and bwave<br />

amplitude (p = 0.007), with significant increases in a-wave in<br />

the 2nd blood Pb tertile (6.0–10.0 :g/dL), and a-wave and b-wave in<br />

the 3rd blood Pb tertile (10.5–32.5 :g/dL), compared to the 1st blood<br />

Pb tertile.<br />

Significant covariate adjusted odds ratio (OR) <strong>for</strong> cataracts in 5th<br />

tibia bone Pb quintile (31.0–125 :g/g), OR = 3.19 (95% CI: 1.48,<br />

6.90), p = 0.01. OR <strong>for</strong> cataracts were not significantly associated<br />

with patella bone Pb (5th quintile: 43.0–165 :g/g), OR = 1.88 (95%<br />

CI: 0.88, 4.02), or blood Pb (5th quintile: 8.17–35.0 :g/dL), OR =<br />

0.89 (95% CI: 0.46, 1.72).<br />

Covariates retained: age, smoking, history <strong>of</strong> diabetes, daily intake<br />

<strong>of</strong> vitamin C, vitamin E, and carotenoids.


AX6-259<br />

Table AX6-9.10 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> on Ocular Health in Children and Adults<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Adults<br />

Europe<br />

Cavalleri et al. (1982)<br />

Italy<br />

NR<br />

Design = cross-sectional cohort<br />

Subjects: adult male vinyl chloride pipe<br />

manufacture workers, exposed to Pb stearate<br />

(n = 35), mean age 45 yr (SD 14, range 21–<br />

59); reference group (n = 35) matched <strong>for</strong><br />

age, smoking, and alcohol consumption.<br />

Outcome measures: visual field<br />

Analysis: comparison <strong>of</strong> outcome measures<br />

between Pb workers and reference group<br />

Blood Pb (:g/dL) mean<br />

(SD, range):<br />

Pb: 46 (14, 21–82)<br />

Reference: 23 (4, 21–37)<br />

Urine Pb (:g/L) mean (SD,<br />

range):<br />

Pb: 71 (18, 44–118)<br />

Reference: 30 (5, 21–42)<br />

Visual sensitivity was significantly (p = 0.003) lower in Pb workers<br />

compared to the reference group; however, visual sensitivity index<br />

was not significantly associated with blood or urine Pb. Mesopic<br />

field scotoma prevalence was 10 <strong>of</strong> 35 (28%) in Pb workers and 0%<br />

in the reference group.


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AX6-297


October 2006<br />

<strong>EPA</strong>/600/R-05/144bF<br />

<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong> <strong>of</strong> <strong>II</strong>


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

<strong>Volume</strong> <strong>II</strong><br />

National Center <strong>for</strong> Environmental Assessment-RTP Division<br />

Office <strong>of</strong> Research and Development<br />

U.S. Environmental Protection Agency<br />

Research Triangle Park, NC<br />

<strong>EPA</strong>/600/R-05/144bF<br />

October 2006


PREFACE<br />

National Ambient <strong>Air</strong> <strong>Quality</strong> Standards (NAAQS) are promulgated by the United States<br />

Environmental Protection Agency (<strong>EPA</strong>) to meet requirements set <strong>for</strong>th in Sections 108 and 109<br />

<strong>of</strong> the U.S. Clean <strong>Air</strong> Act. Those two Clean <strong>Air</strong> Act sections require the <strong>EPA</strong> Administrator<br />

(1) to list widespread air pollutants that reasonably may be expected to endanger public health or<br />

welfare; (2) to issue air quality criteria <strong>for</strong> them that assess the latest available scientific<br />

in<strong>for</strong>mation on nature and effects <strong>of</strong> ambient exposure to them; (3) to set “primary” NAAQS to<br />

protect human health with adequate margin <strong>of</strong> safety and to set “secondary” NAAQS to protect<br />

against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade<br />

materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS<br />

<strong>for</strong> a given listed pollutant or class <strong>of</strong> pollutants.<br />

<strong>Lead</strong> was first listed in the mid-1970’s as a “criteria air pollutant” requiring NAAQS<br />

regulation. The scientific in<strong>for</strong>mation pertinent to Pb NAAQS development available at the time<br />

was assessed in the <strong>EPA</strong> document <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>; published in 1977. Based on<br />

the scientific assessments contained in that 1977 lead air quality criteria document (1977 <strong>Lead</strong><br />

AQCD), <strong>EPA</strong> established a 1.5 µg/m 3 (maximum quarterly calendar average) Pb NAAQS in<br />

1978.<br />

To meet Clean <strong>Air</strong> Act requirements noted above <strong>for</strong> periodic review <strong>of</strong> criteria and<br />

NAAQS, new scientific in<strong>for</strong>mation published since the 1977 <strong>Lead</strong> AQCD was later assessed in<br />

a revised <strong>Lead</strong> AQCD and Addendum published in 1986 and in a Supplement to the 1986<br />

AQCD/Addendum published by <strong>EPA</strong> in 1990. A 1990 <strong>Lead</strong> Staff Paper, prepared by <strong>EPA</strong>’s<br />

Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards (OPQPS), drew upon key findings and conclusions<br />

from the 1986 <strong>Lead</strong> AQCD/Addendum and 1990 Supplement (as well as other OAQPSsponsored<br />

lead exposure/risk analyses) in posing options <strong>for</strong> the <strong>EPA</strong> Administrator to consider<br />

with regard to possible revision <strong>of</strong> the Pb NAAQS. However, <strong>EPA</strong> chose not to revise the Pb<br />

NAAQS at that time. Rather, as part <strong>of</strong> implementing a broad 1991 U.S. <strong>EPA</strong> Strategy <strong>for</strong><br />

Reducing <strong>Lead</strong> Exposure, the Agency focused primarily on regulatory and remedial clean-up<br />

ef<strong>for</strong>ts to reduce Pb exposure from a variety <strong>of</strong> non-air sources that posed more extensive public<br />

health risks, as well as other actions to reduce air emissions.<br />

<strong>II</strong>-iii


The purpose <strong>of</strong> this revised <strong>Lead</strong> AQCD is to critically assess the latest scientific<br />

in<strong>for</strong>mation that has become available since the literature assessed in the 1986 <strong>Lead</strong><br />

AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new<br />

in<strong>for</strong>mation useful in evaluating health and environmental effects <strong>of</strong> ambient air lead exposures.<br />

This includes discussion in this document <strong>of</strong> in<strong>for</strong>mation regarding: the nature, sources,<br />

distribution, measurement, and concentrations <strong>of</strong> lead in the environment; multimedia lead<br />

exposure (via air, food, water, etc.) and biokinetic modeling <strong>of</strong> contributions <strong>of</strong> such exposures<br />

to concentrations <strong>of</strong> lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,<br />

as key indices <strong>of</strong> lead exposure).; characterization <strong>of</strong> lead health effects and associated exposureresponse<br />

relationships; and delineation <strong>of</strong> environmental (ecological) effects <strong>of</strong> lead. This final<br />

version <strong>of</strong> the revised <strong>Lead</strong> AQCD mainly assesses pertinent literature published or accepted <strong>for</strong><br />

publication through December 2005.<br />

The First External Review Draft (dated December 2005) <strong>of</strong> the revised <strong>Lead</strong> AQCD<br />

underwent public comment and was reviewed by the Clean <strong>Air</strong> Scientific Advisory Committee<br />

(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public<br />

comments and CASAC recommendations received were taken into account in making<br />

appropriate revisions and incorporating them into a Second External Review Draft (dated May,<br />

2006) which was released <strong>for</strong> further public comment and CASAC review at a public meeting<br />

held June 28-29, 2006. In addition, still further revised drafts <strong>of</strong> the Integrative Synthesis<br />

chapter and the Executive Summary were then issued and discussed during an August 15, 2006<br />

CASAC teleconference call. Public comments and CASAC advice received on these latter<br />

materials, as well as Second External Review Draft materials, were taken into account in making<br />

and incorporating further revisions into this final version <strong>of</strong> this <strong>Lead</strong> AQCD, which is being<br />

issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present<br />

document provide inputs to an associated <strong>Lead</strong> Staff Paper prepared by <strong>EPA</strong>’s Office <strong>of</strong> <strong>Air</strong><br />

<strong>Quality</strong> Planning and Standards (OAQPS), which poses options <strong>for</strong> consideration by the <strong>EPA</strong><br />

Administrator with regard to proposal and, ultimately, promulgation <strong>of</strong> decisions on potential<br />

retention or revision, as appropriate, <strong>of</strong> the current Pb NAAQS.<br />

Preparation <strong>of</strong> this document has been coordinated by staff <strong>of</strong> <strong>EPA</strong>’s National Center <strong>for</strong><br />

Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific<br />

staff, together with experts from academia, contributed to writing <strong>of</strong> document chapters. Earlier<br />

<strong>II</strong>-iv


drafts <strong>of</strong> document materials were reviewed by scientists from other <strong>EPA</strong> units and by non-<strong>EPA</strong><br />

experts in several public peer consultation workshops held by <strong>EPA</strong> in July/August 2005.<br />

NCEA acknowledges the valuable contributions provided by authors, contributors, and<br />

reviewers and the diligence <strong>of</strong> its staff and contractors in the preparation <strong>of</strong> this document. The<br />

constructive comments provided by public commenters and CASAC that served as valuable<br />

inputs contributing to improved scientific and editorial quality <strong>of</strong> the document are also<br />

acknowledged by NCEA.<br />

DISCLAIMER<br />

Mention <strong>of</strong> trade names or commercial products in this document does not constitute<br />

endorsement or recommendation <strong>for</strong> use.<br />

.<br />

<strong>II</strong>-v


<strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(Second External Review Draft)<br />

VOLUME I<br />

EXECUTIVE SUMMARY .........................................................................................................E-1<br />

1. INTRODUCTION ........................................................................................................... 1-1<br />

2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD.......................................... 2-1<br />

3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED<br />

ENVIRONMENTAL CONCENTRATIONS.................................................................. 3-1<br />

4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD<br />

BURDEN IN HUMANS.................................................................................................. 4-1<br />

5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS<br />

AND IN VITRO TEST SYSTEMS................................................................................. 5-1<br />

6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS<br />

ASSOCIATED WITH LEAD EXPOSURE.................................................................... 6-1<br />

7. ENVIRONMENTAL EFFECTS OF LEAD ................................................................... 7-1<br />

8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH<br />

EFFECTS INFORMATION............................................................................................ 8-1<br />

VOLUME <strong>II</strong><br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS)..................................................... AX4-1<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN<br />

LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS)................ AX5-1<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH<br />

EFFECTS ASSOCIATED WITH LEAD EXPOSURE)................................. AX6-1<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD).................................. AX7-1<br />

<strong>II</strong>-vi


Table <strong>of</strong> Contents<br />

PREFACE......................................................................................................................................iii<br />

DISCLAIMER ................................................................................................................................ v<br />

List <strong>of</strong> Tables ................................................................................................................................. xi<br />

List <strong>of</strong> Figures..............................................................................................................................xiii<br />

Authors, Contributors, and Reviewers.......................................................................................... xv<br />

U.S. Environmental Protection Agency Project Team <strong>for</strong> Development<br />

<strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong>.............................................................................................. xxi<br />

U.S. Environmental Protection Agency Science Advisory Board (SAB)<br />

Staff Office Clean <strong>Air</strong> Scientific Advisory Committee (CASAC).......................................xxiii<br />

Abbreviations and Acronyms ..................................................................................................... xxv<br />

AX7. CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD).................... AX7-1<br />

AX7.1 TERRESTRIAL ECOSYSTEMS............................................................ AX7-1<br />

AX7.1.1 Methodologies Used in Terrestrial Ecosystems<br />

Research............................................................................... AX7-1<br />

AX7.1.1.1 <strong>Lead</strong> Isotopes and Apportionment................. AX7-1<br />

AX7.1.1.2 Speciation in Assessing <strong>Lead</strong><br />

Bioavailability in the Terrestrial<br />

Environment................................................... AX7-3<br />

AX7.1.1.3 Tools <strong>for</strong> Bulk <strong>Lead</strong> Quantification<br />

and Speciation................................................ AX7-9<br />

AX7.1.1.4 Biotic Ligand Model.................................... AX7-18<br />

AX7.1.1.5 Soil Amendments......................................... AX7-19<br />

AX7.1.2 Distribution <strong>of</strong> Atmospherically Delivered <strong>Lead</strong> in<br />

Terrestrial Ecosystems....................................................... AX7-22<br />

AX7.1.2.1 Speciation <strong>of</strong> Atmospherically-Delivered<br />

<strong>Lead</strong> in Terrestrial Ecosystems.................... AX7-24<br />

AX7.1.2.2 Tracing the Fate <strong>of</strong> Atmospherically-<br />

Delivered <strong>Lead</strong> in Terrestrial<br />

Ecosystems................................................... AX7-31<br />

AX7.1.2.3 Inputs/Outputs <strong>of</strong> Atmospherically-<br />

Delivered <strong>Lead</strong> in Terrestrial<br />

Ecosystems................................................... AX7-34<br />

AX7.1.2.4 Resistance Mechanisms ............................... AX7-44<br />

AX7.1.2.5 Physiological Effects <strong>of</strong> <strong>Lead</strong> ...................... AX7-46<br />

AX7.1.2.6 Factors that Modify Organism Response..... AX7-48<br />

AX7.1.2.7 Summary...................................................... AX7-55<br />

AX7.1.3 Exposure-Response <strong>of</strong> Terrestrial Species......................... AX7-57<br />

AX7.1.3.1 Summary <strong>of</strong> Conclusions from the<br />

1986 <strong>Lead</strong> <strong>Criteria</strong> Document...................... AX7-59<br />

AX7.1.3.2 Recent Studies on the Effects <strong>of</strong> <strong>Lead</strong><br />

on Primary Producers................................... AX7-61<br />

<strong>II</strong>-vii<br />

Page


Table <strong>of</strong> Contents<br />

(cont’d)<br />

<strong>II</strong>-viii<br />

Page<br />

AX7.1.3.3 Recent Studies on the Effects <strong>of</strong> <strong>Lead</strong><br />

on Consumers............................................... AX7-64<br />

AX7.1.3.4 Recent Studies on the Effects <strong>of</strong> <strong>Lead</strong><br />

on Decomposers........................................... AX7-81<br />

AX7.1.3.5 Summary...................................................... AX7-86<br />

AX7.1.4 Effects <strong>of</strong> <strong>Lead</strong> on Natural Terrestrial Ecosystems ........... AX7-88<br />

AX7.1.4.1 Effects <strong>of</strong> Terrestrial Ecosystem Stresses<br />

on <strong>Lead</strong> Cycling........................................... AX7-89<br />

AX7.1.4.2 Effects <strong>of</strong> <strong>Lead</strong> Exposure on Natural<br />

Ecosystem Structure and Function............... AX7-95<br />

AX7.1.4.3 Effects <strong>of</strong> <strong>Lead</strong> on Energy Flows and<br />

Biogeochemical Cycling.............................. AX7-99<br />

AX7.1.4.4 Summary.................................................... AX7-105<br />

AX7.2 AQUATIC ECOSYSTEMS................................................................. AX7-106<br />

AX7.2.1 Methodologies Used in Aquatic Ecosystem Research..... AX7-106<br />

AX7.2.1.1 Analytical Methods.................................... AX7-107<br />

AX7.2.1.2 Ambient Water <strong>Quality</strong> <strong>Criteria</strong>:<br />

Development.............................................. AX7-108<br />

AX7.2.1.3 Ambient Water <strong>Quality</strong> <strong>Criteria</strong>:<br />

Bioavailability Issues................................. AX7-111<br />

AX7.2.1.4 Sediment <strong>Quality</strong> <strong>Criteria</strong>:<br />

Development and Bioavailability Issues.... AX7-113<br />

AX7.2.1.5 Metal Mixtures........................................... AX7-116<br />

AX7.2.1.6 Background <strong>Lead</strong>....................................... AX7-117<br />

AX7.2.2 Distribution <strong>of</strong> <strong>Lead</strong> in Aquatic Ecosystems ................... AX7-117<br />

AX7.2.2.1 Speciation <strong>of</strong> <strong>Lead</strong> in Aquatic<br />

Ecosystems................................................. AX7-118<br />

AX7.2.2.2 Spatial Distribution <strong>of</strong> <strong>Lead</strong> in<br />

Aquatic Ecosystems................................... AX7-122<br />

AX7.2.2.3 Tracing the Fate and Transport <strong>of</strong><br />

<strong>Lead</strong> in Aquatic Ecosystems...................... AX7-142<br />

AX7.2.2.4 Summary.................................................... AX7-145<br />

AX7.2.3 Aquatic Species Response/Mode <strong>of</strong> Action..................... AX7-146<br />

AX7.2.3.1 <strong>Lead</strong> Uptake............................................... AX7-146<br />

AX7.2.3.2 Resistance Mechanisms ............................. AX7-152<br />

AX7.2.3.3 Physiological Effects <strong>of</strong> <strong>Lead</strong> .................... AX7-159<br />

AX7.2.3.4 Factors That Modify Organism<br />

Response to <strong>Lead</strong> ....................................... AX7-162<br />

AX7.2.3.5 Factors Associated with Global<br />

Climate Change.......................................... AX7-174<br />

AX7.2.3.6 Summary.................................................... AX7-174


Table <strong>of</strong> Contents<br />

(cont’d)<br />

<strong>II</strong>-ix<br />

Page<br />

AX7.2.4 Exposure/Response <strong>of</strong> Aquatic Species........................... AX7-175<br />

AX7.2.4.1 Summary <strong>of</strong> Conclusions From the<br />

Previous <strong>Criteria</strong> Document....................... AX7-175<br />

AX7.2.4.2 Recent Studies on Effects <strong>of</strong> <strong>Lead</strong> on<br />

Primary Producers...................................... AX7-177<br />

AX7.2.4.3 Recent Studies on Effects <strong>of</strong> <strong>Lead</strong><br />

on Consumers............................................. AX7-183<br />

AX7.2.4.4 Recent Studies on Effects <strong>of</strong> <strong>Lead</strong><br />

on Decomposers......................................... AX7-193<br />

AX7.2.4.5 Summary.................................................... AX7-193<br />

AX7.2.5 Effects <strong>of</strong> <strong>Lead</strong> on Natural Aquatic Ecosystems ............. AX7-194<br />

AX7.2.5.1 Case Study: Coeur d’Alene River<br />

Watershed .................................................. AX7-196<br />

AX7.2.5.2 Biotic Condition......................................... AX7-198<br />

AX7.2.5.3 Summary.................................................... AX7-209<br />

REFERENCES .................................................................................................... AX7-211


List <strong>of</strong> Tables<br />

AX7-1.1.1 Relative Standard Deviation (RSD) <strong>for</strong> <strong>Lead</strong> Isotope Ratios on<br />

Selected Mass Spectrometers................................................................... AX7-2<br />

AX7-1.1.2 National Institute <strong>of</strong> Standards and Technology <strong>Lead</strong> SRMs................ AX7-10<br />

AX7-1.1.3 Characteristics <strong>for</strong> Direct Speciation Techniques.................................. AX7-17<br />

AX7-1.2.1 Tissue <strong>Lead</strong> Levels in Birds Causing Effects ........................................ AX7-43<br />

AX7-1.3.1 Plant Toxicity Data Used to Develop the Eco-SSL............................... AX7-62<br />

AX7-1.3.2 Plant Toxicity Data Not Used to Develop the Eco-SSL........................ AX7-63<br />

AX7-1.3.3 Avian Toxicity Data Used to Develop the Eco-SSL ............................. AX7-66<br />

AX7-1.3.4 Mammalian Toxicity Data Used to Develop the Eco-SSL.................... AX7-72<br />

AX7-1.3.5 Invertebrate Toxicity Data Used to Develop the Eco-SSL.................... AX7-82<br />

AX7-1.3.6 Invertebrate Toxicity Data Not Used to Develop the Eco-SSL............. AX7-84<br />

AX7-2.1.1 Common Analytical Methods <strong>for</strong> Measuring <strong>Lead</strong> in Water,<br />

Sediment, and Tissue .......................................................................... AX7-107<br />

AX7-2.1.2 Development <strong>of</strong> Current Acute Freshwater <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong> ............. AX7-109<br />

AX7-2.1.3 Recommended Sediment <strong>Quality</strong> Guidelines <strong>for</strong> <strong>Lead</strong> ....................... AX7-115<br />

AX7-2.2.1 NAWQA Land Use Categories and Natural/Ambient<br />

Classification........................................................................................ AX7-125<br />

AX7-2.2.2 Summary Statistics <strong>of</strong> Ambient and Natural Levels <strong>of</strong> Dissolved<br />

<strong>Lead</strong> in Surface Water ......................................................................... AX7-126<br />

AX7-2.2.3 Summary Statistics <strong>of</strong> Ambient and Natural Levels <strong>of</strong> Total<br />

<strong>Lead</strong> in


List <strong>of</strong> Tables<br />

(cont’d)<br />

AX7-2.3.1 Bioconcentration Factors <strong>for</strong> Aquatic Plants ....................................... AX7-151<br />

AX7-2.3.2 Bioconcentration Factors <strong>for</strong> Aquatic Invertebrates............................ AX7-151<br />

AX7-2.4.1 Effects <strong>of</strong> <strong>Lead</strong> to Freshwater and Marine Invertebrates..................... AX7-185<br />

AX7-2.4.2 Effects <strong>of</strong> Pb to Freshwater and Marine Fish....................................... AX7-190<br />

AX7-2.4.3 Nonlethal Effects in Amphibians......................................................... AX7-192<br />

AX7-2.5.1 Ecological Attributed Studies by Maret et al. (2003) in the<br />

Coeur d’Alene Watershed.................................................................... AX7-197<br />

AX7-2.5.2 Essential Ecological Attributes <strong>for</strong> Natural Aquatic Ecosystems<br />

Affected by <strong>Lead</strong>.................................................................................. AX7-200<br />

<strong>II</strong>-xi<br />

Page


List <strong>of</strong> Figures<br />

Number Page<br />

AX7-1.1.1 Relationship <strong>of</strong> bioaccessibility (low, medium, high) versus<br />

speciation as shown with scanning electron micrographs <strong>of</strong><br />

various Pb-bearing materials........................................................................ AX7-5<br />

AX7-1.1.2 Variation <strong>of</strong> bioavailability with particle size.............................................. AX7-7<br />

AX7-1.1.3 Illustration <strong>of</strong> particle lability and bioavailability at two different<br />

sites with similar total Pb concentrations and Pb <strong>for</strong>ms .............................. AX7-8<br />

AX7-1.1.4 Scanning electron micrograph <strong>of</strong> a large native Pb particle showing<br />

outer ring <strong>of</strong> highly bioavailable Pb-chloride and Pb-oxide........................ AX7-8<br />

AX7-1.1.5 Bulk lead versus single species modality................................................... AX7-12<br />

AX7-1.2.1 Long-term (1982-1989) annual trends in lead concentrations (µg/L)<br />

in Lewes, Delaware precipitation .............................................................. AX7-35<br />

AX7-1.3.1 Avian reproduction and growth toxicity data considered in<br />

development <strong>of</strong> the Eco-SSL ..................................................................... AX7-69<br />

AX7-1.3.2 Mammalian reproduction and growth toxicity data considered in<br />

development <strong>of</strong> the Eco-SSL ..................................................................... AX7-81<br />

AX7-2.2.1 Distribution <strong>of</strong> aqueous lead species as a function <strong>of</strong> pH based on<br />

a concentration <strong>of</strong> 1 µg Pb/L.................................................................... AX7-119<br />

AX7-2.2.2 <strong>Lead</strong> speciation versus chloride content .................................................. AX7-121<br />

AX7-2.2.3 Spatial distribution <strong>of</strong> natural and ambient surface water/sediment<br />

sites .......................................................................................................... AX7-128<br />

AX7-2.2.4 Spatial distribution <strong>of</strong> natural and ambient liver tissue sample sites....... AX7-129<br />

AX7-2.2.5 Spatial distribution <strong>of</strong> natural and ambient whole organism tissue<br />

sample sites .............................................................................................. AX7-130<br />

AX7-2.2.6 Frequency distribution <strong>of</strong> ambient and natural levels <strong>of</strong> surface<br />

water dissolved lead (µg/L). .................................................................... AX7-131<br />

AX7-2.2.7 Spatial distribution <strong>of</strong> dissolved lead in surface water (N = 3445). ........ AX7-132<br />

<strong>II</strong>-xii


List <strong>of</strong> Figures<br />

(cont’d)<br />

Number Page<br />

AX7-2.2.8 Frequency distribution <strong>of</strong> ambient and natural levels <strong>of</strong> bulk<br />

sediment


Authors, Contributors, and Reviewers<br />

CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND<br />

MODELS OF LEAD BURDEN IN HUMANS)<br />

Chapter Managers/Editors<br />

Dr. James Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principal Authors<br />

Dr. Brian Gulson—Graduate School <strong>of</strong> the Environment, Macquarie University<br />

Sydney, NSW 2109, Australia<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS<br />

AND LABORATORY ANIMALS)<br />

Chapter Managers/Editors<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xiv


Principal Authors<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Anuradha Mudipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Stephen Lasley—Dept. <strong>of</strong> Biomedical and Therapeutic Sciences, Univ. <strong>of</strong> Illinois College <strong>of</strong><br />

Medicine, PO Box 1649, Peoria, IL 61656<br />

Dr. Lori White—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001<br />

Dr. N.D. Vaziri—Division <strong>of</strong> Nephrology and Hypertension, University <strong>of</strong> Cali<strong>for</strong>nia – Irvine<br />

Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868<br />

Dr. John Pierce Wise, Sr.—Maine Center <strong>for</strong> Toxicology and Environmental Health,<br />

Department <strong>of</strong> Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME<br />

04104-9300<br />

Dr. Harvey C. Gonick—David Geffen School <strong>of</strong> Medicine, University <strong>of</strong> Cali<strong>for</strong>nia at<br />

Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049<br />

Dr. Gene E. Watson—University <strong>of</strong> Rochester Medical Center, Box 705, Rochester, NY 14642<br />

Dr. Rodney Dietert—Institute <strong>for</strong> Comparative and Environmental Toxicology, College <strong>of</strong><br />

Veterinary Medicine, Cornell University, Ithaca, NY 14853<br />

Contributors and Reviewers<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David A. Lawrence—Dept <strong>of</strong> Environmental and Clinical Immunology, Empire State Plaza<br />

P.O. Box 509, Albany, NY 12201<br />

<strong>II</strong>-xv


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Michael J. McCabe, Jr.—Dept <strong>of</strong> Environmental Medicine, University <strong>of</strong> Rochester,<br />

575 Elmwood Avenue, Rochester, NY 14642<br />

Dr. Theodore I. Lidsky—New York State Institute <strong>for</strong> Basic Research, 1050 Forest RD,<br />

Staten Island, NY 10314<br />

Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001<br />

Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD<br />

EXPOSURE EFFECTS)<br />

Chapter Managers/Editors<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xvi


Principal Authors<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. David Bellinger—Children’s Hospital, Farley Basement, Box 127, 300 Longwood Avenue,<br />

Boston, MA 02115<br />

Dr. Margit Bleecker—Center <strong>for</strong> Occupational and Environmental Neurology, 2 Hamill Road,<br />

Suite 225, Baltimore, MD 21210<br />

Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.<br />

Akron, NY 14001<br />

Dr. Kim Dietrich—University <strong>of</strong> Cincinnati College <strong>of</strong> Medicine, 3223 Eden Avenue,<br />

Kettering Laboratory, Room G31, Cincinnati, OH 45267<br />

Dr. Pam Factor-Litvak—Columbia University Mailman School <strong>of</strong> Public Health,<br />

722 West 168th Street, Room 1614, New York, NY 10032<br />

Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713<br />

Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Mérida, Yucatán, México & National Institute<br />

<strong>of</strong> Public Health, Cuernavaca, Morelos, Mexico<br />

Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School <strong>of</strong> Public Health<br />

& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112<br />

Dr. Kyle Steenland—Rollins School <strong>of</strong> Public Health, Emory University, 1518 Clifton Road,<br />

Room 268, Atlanta, GA 30322<br />

Dr. Virginia Weaver—Johns Hopkins Bloomberg School <strong>of</strong> Public Health, 615 North Wolfe<br />

Street, Room 7041, Baltimore, MD 21205<br />

Contributors and Reviewers<br />

Dr. J. Michael Davis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Lester D. Grant—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Kazuhiko Ito—Nelson Institute <strong>of</strong> Environmental Medicine, New York University School <strong>of</strong><br />

Medicine, Tuxedo, NY 10987<br />

<strong>II</strong>-xvii


Contributors and Reviewers<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Kathryn Mahaffey—Office <strong>of</strong> Prevention, Pesticides and Toxic Substances,<br />

U.S. Environmental Protection Agency, Washington, DC 20460<br />

Dr. Karen Martin—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Zachary Pekar—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Beth Hassett-Sipple—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Chapter Manager/Editor<br />

CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Principle Authors<br />

Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,<br />

Ontario, L5N 3C9 Canada<br />

Dr. James Kaste—Department <strong>of</strong> Earth Sciences, Dartmouth College, 352 Main Street,<br />

Hanover, NH 03755<br />

Dr. John Drexler—Department <strong>of</strong> Geological Sciences, University <strong>of</strong> Colorado,<br />

1216 Gillespie Drive, Boulder, CO 80305<br />

Dr. Chris Johnson—Department <strong>of</strong> Civil and Environmental Engineering, Syracuse University,<br />

365 Link Hall, Syracuse, NY 13244<br />

Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321<br />

<strong>II</strong>-xviii


Principle Authors<br />

(cont’d)<br />

Authors, Contributors, and Reviewers<br />

(cont’d)<br />

Dr. Dwayne Moore—Cantox Environmental, Inc., 1550A Laperriere Avenue, Suite 103,<br />

Ottawa, Ontario, K1Z 7T2 Canada<br />

Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004<br />

Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,<br />

Winchester, MA 01890<br />

Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place,<br />

Suite 202, Winchester, MA 01890<br />

Contributors and Reviewers<br />

Dr. Jerome Nriagu—Department <strong>of</strong> Environmental Health Sciences, 109 South Observatory,<br />

University <strong>of</strong> Michigan, Ann Arbor, MI 48109<br />

Dr. Judith Weis—Department <strong>of</strong> Biology, Rutgers University, Newark, NJ 07102<br />

Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Ginger Tennant—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental<br />

Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Gail Lacey—Office <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> Planning and Standards, U.S. Environmental Protection<br />

Agency, Research Triangle Park, NC 27711<br />

Dr. John Vandenberg—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xix


Executive Direction<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

Dr. Lester D. Grant (Director)—National Center <strong>for</strong> Environmental Assessment-RTP Division,<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Scientific Staff<br />

Dr. Lori White (<strong>Lead</strong> Team <strong>Lead</strong>er)—National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. James S. Brown—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Robert Elias—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Dr. Brooke Hemming—National Center <strong>for</strong> Environmental Assessment (B243-01), U.S.<br />

Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Jee Young Kim—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Dennis Kotchmar—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Timothy Lewis—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Anuradha Muldipalli—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Srikanth Nadadur—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Paul Reinhart—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. Mary Ross— National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Dr. David Svendsgaard—National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

<strong>II</strong>-xx


Technical Support Staff<br />

U.S. Environmental Protection Agency Project Team<br />

<strong>for</strong> Development <strong>of</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(cont’d)<br />

Mr. Douglas B. Fennell—Technical In<strong>for</strong>mation Specialist, National Center <strong>for</strong> Environmental<br />

Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC<br />

27711 (Retired)<br />

Ms. Emily R. Lee—Management Analyst, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Diane H. Ray—Program Specialist, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Ms. Donna Wicker—Administrative Officer, National Center <strong>for</strong> Environmental Assessment<br />

(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)<br />

Mr. Richard Wilson—Clerk, National Center <strong>for</strong> Environmental Assessment (B243-01),<br />

U.S. Environmental Protection Agency, Research Triangle Park, NC 27711<br />

Document Production Staff<br />

Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Mr. John A. Bennett—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,<br />

Suite 1450, McLean, VA 22102<br />

Ms. Sandra L. Hughey—Technical In<strong>for</strong>mation Specialist, Library Associates <strong>of</strong> Maryland,<br />

11820 Parklawn Drive, Suite 400, Rockville, MD 20852<br />

Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards<br />

Mill Road, Suite 201, Raleigh, NC 27607<br />

Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,<br />

Suite 220, Morrisville, NC 27560<br />

<strong>II</strong>-xxi


Chair<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,<br />

Albuquerque, NM<br />

Members<br />

Dr. Joshua Cohen—Faculty, Center <strong>for</strong> the Evaluation <strong>of</strong> Value and Risk, Institute <strong>for</strong> Clinical<br />

Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA<br />

Dr. Deborah Cory-Slechta—Director, University <strong>of</strong> Medicine and Dentistry <strong>of</strong> New Jersey and<br />

Rutgers State University, Piscataway, NJ<br />

Dr. Ellis Cowling*—University Distinguished Pr<strong>of</strong>essor-at-Large, North Carolina State<br />

University, Colleges <strong>of</strong> Natural Resources and Agriculture and Life Sciences, North Carolina<br />

State University, Raleigh, NC<br />

Dr. James D. Crapo [M.D.]*—Pr<strong>of</strong>essor, Department <strong>of</strong> Medicine, National Jewish Medical and<br />

Research Center, Denver, CO<br />

Dr. Bruce Fowler—Assistant Director <strong>for</strong> Science, Division <strong>of</strong> Toxicology and Environmental<br />

Medicine, Office <strong>of</strong> the Director, Agency <strong>for</strong> Toxic Substances and Disease Registry, U.S.<br />

Centers <strong>for</strong> Disease Control and Prevention (ATSDR/CDC), Chamblee, GA<br />

Dr. Andrew Friedland—Pr<strong>of</strong>essor and Chair, Environmental Studies Program, Dartmouth<br />

College, Hanover, NH<br />

Dr. Robert Goyer [M.D.]—Emeritus Pr<strong>of</strong>essor <strong>of</strong> Pathology, Faculty <strong>of</strong> Medicine, University <strong>of</strong><br />

Western Ontario (Canada), Chapel Hill, NC<br />

Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO<br />

Dr. Bruce Lanphear [M.D.]—Sloan Pr<strong>of</strong>essor <strong>of</strong> Children’s Environmental Health, and the<br />

Director <strong>of</strong> the Cincinnati Children’s Environmental Health Center at Cincinnati Children’s<br />

Hospital Medical Center and the University <strong>of</strong> Cincinnati, Cincinnati, OH<br />

Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (<strong>US</strong>GS),<br />

Menlo Park, CA<br />

<strong>II</strong>-xxii


Members<br />

(cont’d)<br />

U.S. Environmental Protection Agency<br />

Science Advisory Board (SAB) Staff Office<br />

Clean <strong>Air</strong> Scientific Advisory Committee (CASAC)<br />

(cont’d)<br />

Dr. Frederick J. Miller*—Consultant, Cary, NC<br />

Dr. Paul Mushak—Principal, PB Associates, and Visiting Pr<strong>of</strong>essor, Albert Einstein College <strong>of</strong><br />

Medicine (New York, NY), Durham, NC<br />

Dr. Michael Newman—Pr<strong>of</strong>essor <strong>of</strong> Marine Science, School <strong>of</strong> Marine Sciences, Virginia<br />

Institute <strong>of</strong> Marine Science, College <strong>of</strong> William & Mary, Gloucester Point, VA<br />

Mr. Richard L. Poirot*—Environmental Analyst, <strong>Air</strong> Pollution Control Division, Department <strong>of</strong><br />

Environmental Conservation, Vermont Agency <strong>of</strong> Natural Resources, Waterbury, VT<br />

Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA<br />

Dr. Joel Schwartz—Pr<strong>of</strong>essor, Environmental Health, Harvard University School <strong>of</strong> Public<br />

Health, Boston, MA<br />

Dr. Frank Speizer [M.D.]*—Edward Kass Pr<strong>of</strong>essor <strong>of</strong> Medicine, Channing Laboratory,<br />

Harvard Medical School, Boston, MA<br />

Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,<br />

Moscow, ID<br />

Dr. Barbara Zielinska*—Research Pr<strong>of</strong>essor, Division <strong>of</strong> Atmospheric Science, Desert Research<br />

Institute, Reno, NV<br />

SCIENCE ADVISORY BOARD STAFF<br />

Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,<br />

Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)<br />

(Physical/Courier/FedEx Address: Fred A. Butterfield, <strong>II</strong>I, <strong>EPA</strong> Science Advisory Board Staff<br />

Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,<br />

DC 20004, Telephone: 202-343-9994)<br />

*Members <strong>of</strong> the statutory Clean <strong>Air</strong> Scientific Advisory Committee (CASAC) appointed by the<br />

U.S. <strong>EPA</strong> Administrator<br />

<strong>II</strong>-xxiii


Abbreviations and Acronyms<br />

αFGF α-fibroblast growth factor<br />

AA arachidonic acid<br />

AAL active avoidance learning<br />

AAS atomic absorption spectroscopy<br />

ABA β-aminoisobutyric acid<br />

ACBP Achenbach Child Behavior Pr<strong>of</strong>ile<br />

ACE angiotensin converting enzyme<br />

ACh acetylcholine<br />

AChE acetylcholinesterase<br />

ACR acute-chronic ratio<br />

AD adult<br />

ADC analog digital converter<br />

ADP adenosine diphosphate<br />

AE anion exchange<br />

AEA N-arachidonylethanolamine<br />

AFC antibody <strong>for</strong>ming cells<br />

2-AG 2-arachidonylglycerol<br />

A horizon uppermost layer <strong>of</strong> soil (litter and humus)<br />

AHR aryl hydrocarbon receptor<br />

AI angiotensin I<br />

ALA ∗-aminolevulinic acid<br />

ALAD ∗-aminolevulinic acid dehydratase<br />

ALAS aminolevulinic acid synthetase<br />

ALAU urinary δ-aminolevulinic acid<br />

ALD aldosterone<br />

ALS amyotrophic lateral sclerosis<br />

ALT alanine aminotransferase<br />

ALWT albumin weight<br />

AMEM Alpha Minimal Essential Medium<br />

AMP adenosine monophosphate<br />

ANCOVA analysis <strong>of</strong> covariance<br />

ANF atrial natriuretic factor<br />

Ang <strong>II</strong> angiotensin <strong>II</strong><br />

<strong>II</strong>-xxiv


ANOVA analysis <strong>of</strong> variance<br />

ANP atrial natriuretic peptide<br />

AP alkaline phosphatase<br />

AP-1 activated protein-1<br />

ApoE apolipoprotein E<br />

AQCD <strong>Air</strong> <strong>Quality</strong> <strong>Criteria</strong> Document<br />

Arg arginine<br />

AS52 cells derived from the CHO cell line<br />

ASGP-R aceyl glycoprotein receptor<br />

AST aspartate aminotransferase<br />

ASV anode stripping voltammetry<br />

3-AT 3-aminotriazole; 3-amino triazide<br />

ATP adenosine triphosphate<br />

ATP1A2 sodium-potassium adenosine triphosphase α2<br />

ATPase adenosine triphosphatase<br />

ATSDR Agency <strong>for</strong> Toxic Substances and Disease Research<br />

AVCD atrioventricular conduction deficit<br />

AVS acid volatile sulfide<br />

AWQC ambient water quality criteria<br />

∃ beta-coefficient; slope <strong>of</strong> an equation<br />

∃FGF ∃-fibroblast growth factor<br />

17∃–HS 17∃-hydroxysteriod<br />

3∃-HSD 3∃-hydroxysteriod dehydrogenase<br />

17∃-HSDH 17∃-hydroxysteriod dehydrogenase<br />

6∃-OH-cortisol 6-∃-hydroxycortisol<br />

B both<br />

BAEP brainstem auditory-evoked potentials<br />

BAER brainstem auditory-evoked responses<br />

BAF bioaccumulation factor<br />

B cell B lymphocyte<br />

BCFs bioconcentration factors<br />

BCS bovine calf serum<br />

BDNF brain derived neurotrophic factor<br />

BDWT body weight changes<br />

BEI biological exposure index<br />

<strong>II</strong>-xxv


BFU-E blood erythroid progenitor<br />

BLL blood lead level<br />

BLM biotic ligand model<br />

BM basement membrane<br />

BMI body mass index<br />

BDNF brain-derived neurotrophic factor<br />

BOTMP Bruinicks-Oseretsky Test <strong>of</strong> Motor Pr<strong>of</strong>iciency<br />

BP blood pressure<br />

BPb blood lead concentration<br />

BSA bovine serum albumin<br />

BSI Brief Symptom Inventory<br />

BTQ Boston Teacher Questionnaire<br />

BUN blood urea nitrogen<br />

bw, b. wt., BW body weight<br />

C3H10T/12 mouse embryo cell line<br />

C3, C4 complement proteins<br />

CA chromosome aberration<br />

CA3 cornu ammonis 3 region <strong>of</strong> hippocampus<br />

45<br />

Ca calcium-45 radionuclide<br />

Ca-ATP calcium-dependent adenosine triphosphate<br />

Ca-ATPase calcium-dependent adenosine triphosphatase<br />

CaCO3<br />

calcium carbonate<br />

CaEDTA calcium disodium ethylenediaminetetraacetic acid<br />

CAL calcitonin<br />

CaM calmodulin<br />

Ca-Mg-ATPase calcium-magnesium-dependent adenosine triphosphatase<br />

cAMP cyclic adenosinemonophosphate<br />

CaNa2 EDTA calcium disodium ethylenediaminetetraacetic acid<br />

CANTAB Cambridge Neuropsychological Testing Automated Battery<br />

CAT catalase; Cognitive Abilities Test<br />

CBCL Achenbach Child Behavior Checklist<br />

CBCL-T Total Behavior Problem Score<br />

CBL cumulative blood lead<br />

CBLI cumulative blood lead index<br />

CCB cytochalasin B<br />

<strong>II</strong>-xxvi


CCD charge-coupled device<br />

CCE Coordination Center <strong>for</strong> Effects<br />

CCL carbon tetrachloride<br />

CCS cosmic calf serum<br />

C-CVRSA<br />

coefficient <strong>of</strong> component variance <strong>of</strong> respiratory sinus arrhythmia<br />

Cd cadmium<br />

109 Cd cadmium-109 radionuclide<br />

CdU urinary cadmium<br />

CEC<br />

cation exchange capacity<br />

CESD, CES-D Center <strong>for</strong> Epidemiologic Studies Depression (scale)<br />

GFAP glial fibrillary acidic protein<br />

CFU-E colony <strong>for</strong>ming unit blood-erythroid progenitor (cell count)<br />

CFU-GEMM colony <strong>for</strong>ming unit blood-pluripotent progenitor (cell count)<br />

CFU-GM blood granulocyte/macrophage progenitor (cell count)<br />

cGMP cyclic guanosine-3',5'-monophosphate<br />

ChAT choline acetyltransferase<br />

CHD coronary heart disease<br />

CHO Chinese hamster ovary cell line<br />

CI confidence interval<br />

CLE-SV competitive ligand-exchange/stripping voltammetry<br />

CLRTAP Convention on Long-Range Transboundary <strong>of</strong> <strong>Air</strong> Pollution<br />

CLS Cincinnati <strong>Lead</strong> Study<br />

CMC criterion maximum concentration<br />

CMI cell-mediated immunity<br />

CNS central nervous system<br />

COH cation-osmotic hemolysis<br />

ConA concanavalin A<br />

COR cortisol<br />

CoTx cotreatment<br />

COX-2 cyclooxygenase-2<br />

CP coproporphryn<br />

CPT current perception threshold<br />

cr creatinine<br />

CRAC calcium release activated calcium reflux<br />

CREB cyclic AMP-response element binding protein<br />

<strong>II</strong>-xxvii


CRF chronic renal failure<br />

CRI chronic renal insufficiency<br />

CSF cerebrospinal fluid<br />

CuZn-SOD copper and zinc-dependent superoxide dismutase<br />

CV conduction velocity<br />

CVLT Cali<strong>for</strong>nia Verbal Learning Test<br />

CVR-R<br />

coefficient <strong>of</strong> variation <strong>of</strong> the R-R interval<br />

CYP cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)<br />

CYP3a11 cytochrome P450 3a11<br />

D D-statistic<br />

DA dopamine; dopaminergic<br />

dbcAMP dibutyryl cyclic adenosine-3',5'-monophosphate<br />

DCV distribution <strong>of</strong> conduction velocities<br />

DEAE diethylaminoethyl (chromatography)<br />

DET diffusive equilibrium thin films<br />

DEYO death <strong>of</strong> young<br />

DFS decayed or filled surfaces, permanent teeth<br />

dfs covariate-adjusted number <strong>of</strong> caries<br />

DG dentate gyrus<br />

DGT diffusive gradient thin films<br />

DL DL-statistic<br />

DMEM Dulbecco’s Minimal Essential Medium<br />

DMEM/F12 Dulbecco’s Minimal Essential Medium/Ham’s F12<br />

DMFS decayed, missing, or filled surfaces, permanent teeth<br />

DMPS 2,3-dimercaptopropane 1-sulfonate<br />

DMSA 2,3-dimercaptosuccinic acid<br />

DMT Donnan membrane technique<br />

DMTU dimethylthiourea<br />

DNA deoxyribonucleic acid<br />

DO distraction osteogenesis<br />

DOC dissolved organic carbon<br />

DOM dissolved organic carbon<br />

DOPAc 3,4-dihydroxyphenylacetic acid<br />

DPASV differential pulse anodic stripping voltammetry<br />

dp/dt rate <strong>of</strong> left ventricular isovolumetric pressure<br />

<strong>II</strong>-xxviii


DPPD N-N-diphenyl-p-phynylene-diamine<br />

DR drinking water<br />

DSA delayed spatial alternation<br />

DTC diethyl dithiocarbomate complex<br />

DTH delayed type hypersensitivity<br />

DTPA diethylenetriaminepentaacetic acid<br />

DTT dithiothreitol<br />

dw dry weight<br />

E embryonic day<br />

E2<br />

estradiol<br />

EBE early biological effect<br />

EBV Epstein-Barr virus<br />

EC European Community<br />

EC50<br />

effect concentration <strong>for</strong> 50% <strong>of</strong> test population<br />

eCB endocannabinoid<br />

ECG electrocardiogram<br />

Eco-SSL ecological soil screening level<br />

EDS energy dispersive spectrometers<br />

EDTA ethylenediaminetetraacetic acid<br />

EEDQ N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone<br />

EEG electroencephalogram<br />

EG egg<br />

EGF epidermal growth factor<br />

EGG effects on eggs<br />

EGPN egg production<br />

EKG electrocardiogram<br />

electro electrophysiological stimulation<br />

EM/CM experimental medium-to-control medium (ratio)<br />

EMEM Eagle’s Minimal Essential Medium<br />

eNOS endothelial nitric oxide synthase<br />

EP erythrocyte protoporphyrin<br />

<strong>EPA</strong> U.S. Environmental Protection Agency<br />

Epi epinephrine<br />

EPMA electron probe microanalysis<br />

EPO erythropoietin<br />

<strong>II</strong>-xxix


EPSC excitatory postsynaptic currents<br />

EPT macroinvertebrates from the Ephemeroptera (mayflies),<br />

Plecoptera (stoneflies), and Trichoptera (caddisflies) group<br />

ERG electroretinogram; electroretinographic<br />

ERL effects range – low<br />

ERM effects range – median<br />

EROD ethoxyresorufin-O-deethylase<br />

ESCA electron spectroscopy <strong>for</strong> chemical analysis<br />

ESRD end-stage renal disease<br />

EST estradiol<br />

ESTH eggshell thinning<br />

ET endothelein; essential tremor<br />

ETOH ethyl alcohol<br />

EXAFS extended X-ray absorption fine structure<br />

EXANES extended X-ray absorption near edge spectroscopy<br />

F F-statistic<br />

F344 Fischer 344 (rat)<br />

FAV final acute value<br />

FBS fetal bovine serum<br />

FCS fetal calf serum<br />

FCV final chronic value<br />

FD food<br />

FEF <strong>for</strong>ced expiratory flow<br />

FEP free erythrocyte protoporphyrin<br />

FERT fertility<br />

FEV1<br />

<strong>for</strong>ced expiratory volume in one second<br />

FGF fibroblast growth factor (e.g., βFGF, αFGF)<br />

FI fixed interval (operant conditioning)<br />

FIAM free ion activity model<br />

FMLP N-<strong>for</strong>myl-L-methionyl-L-leucyl-L-phenylalanine<br />

fMRI functional magnetic resonance imaging<br />

FR fixed-ratio operant conditioning<br />

FSH follicle stimulating hormone<br />

FT3 free triiodothyronine<br />

FT4 free thyroxine<br />

<strong>II</strong>-xxx


FTES free testosterone<br />

FT<strong>II</strong> Fagan Test <strong>of</strong> Infant Intelligence<br />

FTPLM flow-through permeation liquid membranes<br />

FURA-2 1-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benz<strong>of</strong>uranyloxy]-2-(2amino-5-methylphenoxy)<br />

ethane-N,N,N',N'-tetraacetic acid<br />

FVC <strong>for</strong>ced vital capacity<br />

(-GT (-glutamyl transferase<br />

G gestational day<br />

GABA gamma aminobutyric acid<br />

GAG glycosaminoglycan<br />

G12 CHV79 cells derived from the V79 cell line<br />

GCI General Cognitive Index<br />

GD gestational day<br />

GDP guanosine diphosphate<br />

GEE generalized estimating equations<br />

GFAAS graphite furnace atomic absorption spectroscopy<br />

GFR glomerular filtration rate<br />

GGT (-glutamyl transferase<br />

GH growth hormone<br />

GI gastrointestinal<br />

GIME-VIP gel integrated microelectrodes combined with voltammetric<br />

in situ pr<strong>of</strong>iling<br />

GIS geographic in<strong>for</strong>mation system<br />

GLU glutamate<br />

GMAV genus mean acute value<br />

GMCV genus mean chronic value<br />

GMP guanosine monophosphate<br />

GMPH general morphology<br />

GnRH gonadotropin releasing hormone<br />

GOT aspartate aminotransferase<br />

GP gross productivity<br />

G6PD, G6PDH glucose-6-phosphate dehydrogenase<br />

GPEI glutathione S-transferase P enhancer element<br />

gp91 phox NAD(P)H oxidase<br />

GPT glutamic-pyruvic transaminase<br />

GPx glutathione peroxidase<br />

<strong>II</strong>-xxxi


GRO growth<br />

GRP78 glucose-regulated protein 78<br />

GSD geometric standard deviation<br />

GSH reduced glutathione<br />

GSIM gill surface interaction model<br />

GSSG glutathione disulfide<br />

GST glutathione-S-transferase<br />

GSTP placental glutathione transferase<br />

GTP guanosine triphosphate<br />

GV gavage<br />

H + acidity<br />

3<br />

H hydrogen-3 radionuclide (tritium)<br />

HA humic acid; hydroxyapatite<br />

Hb hemoglobin<br />

HBEF Hubbard Brook Experimenatl Forest<br />

HBSS Hank’s Balanced Salt Solution<br />

HCG; hCG human chorionic gonadotropin<br />

Hct hematocrit<br />

HDL high-density lipoprotein (cholesterol)<br />

HEP habitat evaluation procedure<br />

HET Binghamton heterogeneous stock<br />

HFPLM hollow fiber permeation liquid membranes<br />

Hgb hemoglobin<br />

HGF hepatocyte growth factor<br />

HH hydroxylamine hydrochloride<br />

H-H high-high<br />

HHANES Hispanic Health and Nutrition Examination Survey<br />

H-L high-low<br />

HLA human leukocyte antigen<br />

H-MEM minimum essential medium/nutrient mixture–F12-Ham<br />

HMP hexose monophosphate shunt pathway<br />

HNO3<br />

nitric acid<br />

H2O2<br />

hydrogen peroxide<br />

HOME Home Observation <strong>for</strong> Measurement <strong>of</strong> Environment<br />

HOS TE human osteosarcoma cells<br />

<strong>II</strong>-xxxii


HPLC high-pressure liquid chromatography<br />

H3PO4<br />

phosphoric acid<br />

HPRT hypoxanthine phosphoribosyltransferase (gene)<br />

HR heart rate<br />

HSI habitat suitability indices<br />

H2SO4<br />

sulfuric acid<br />

HSPG heparan sulfate proteoglycan<br />

Ht hematocrit<br />

HTC hepatoma cells<br />

hTERT catalytic subunit <strong>of</strong> human telomerase<br />

HTN hypertension<br />

IBL integrated blood lead index<br />

IBL Η WRAT-R integrated blood lead index Η Wide Range Achievement<br />

Test-Revised (interaction)<br />

ICD International Classification <strong>of</strong> Diseases<br />

ICP inductively coupled plasma<br />

ICP-AES inductively coupled plasma atomic emission spectroscopy<br />

ICP-MS, ICPMS inductively coupled plasma mass spectrometry<br />

ID-MS isotope dilution mass spectrometry<br />

IFN interferon (e.g., IFN-()<br />

Ig immunoglobulin (e.g., IgA, IgE, IgG, IgM)<br />

IGF-1 insulin-like growth factor 1<br />

IL interleukin (e.g., IL-1, IL-1∃, IL-4, IL-6, IL-12)<br />

ILL incipient lethal level<br />

immuno immunohistochemical staining<br />

IMP inosine monophosphate<br />

iNOS inducible nitric oxide synthase<br />

i.p., IP intraperitoneal<br />

IPSC inhibitory postsynaptic currents<br />

IQ intelligence quotient<br />

IRT interresponse time<br />

ISEL in situ end labeling<br />

ISI interstimulus interval<br />

i.v., IV intravenous<br />

IVCD intraventricular conduction deficit<br />

<strong>II</strong>-xxxiii


JV juvenile<br />

KABC Kaufman Assessment Battery <strong>for</strong> Children<br />

KTEA Kaufman Test <strong>of</strong> Educational Achievement<br />

KXRF, K-XRF K-shell X-ray fluorescence<br />

LA lipoic acid<br />

LB laying bird<br />

LC lactation<br />

LC50<br />

lethal concentration at which 50% <strong>of</strong> exposed animals die<br />

LC74<br />

lethal concentration at which 74% <strong>of</strong> exposed animals die<br />

LD50<br />

lethal dose at which 50% <strong>of</strong> exposed animals die<br />

LDH lactate dehydrogenase<br />

LDL low-density lipoprotein (cholesterol)<br />

L-dopa 3,4-dihydroxyphenylalanine (precursor <strong>of</strong> dopamine)<br />

LE Long Evans (rat)<br />

LET linear energy transfer (radiation)<br />

LH luteinizing hormone<br />

LHRH luteinizing hormone releasing hormone<br />

LN lead nitrate<br />

L-NAME L-N G -nitroarginine methyl ester<br />

LOAEL lowest-observed adverse effect level<br />

LOEC lowest-observed-effect concentration<br />

LOWESS locally weighted scatter plot smoother<br />

LPO lipoperoxide<br />

LPP lipid peroxidation potential<br />

LPS lipopolysaccharide<br />

LT leukotriene<br />

LT50<br />

time to kill 50%<br />

LTER Long-Term Ecological Research (sites)<br />

LTP long term potentiation<br />

LVH left ventricular hypertrophy<br />

µPIXE micr<strong>of</strong>ocused particle induced X-ray emission<br />

µSXRF micr<strong>of</strong>ocused synchrotron-based X-ray fluorescence<br />

MA mature<br />

MA-10 mouse Leydig tumor cell line<br />

MANCOVA multivariate analysis <strong>of</strong> covariance<br />

<strong>II</strong>-xxxiv


MAO monoamine oxidase<br />

MATC maximum acceptable threshold concentration<br />

MDA malondialdehyde<br />

MDA-TBA malondialdehyde-thiobarbituric acid<br />

MDCK kidney epithelial cell line<br />

MDI Mental Development Index (score)<br />

MDRD Modification <strong>of</strong> Diet in Renal Disease (study)<br />

MEM Minimal Essential Medium<br />

MG microglobulin<br />

Mg-ATPase magnesium-dependent adenosine triphosphatase<br />

MiADMSA monoisamyl dimercaptosuccinic acid<br />

Mi-DMSA mi monoisoamyl dimercaptosuccinic acid<br />

MK-801 NMDA receptor antagonist<br />

MLR mixed lymphocyte response<br />

MMSE Mini-Mental State Examination<br />

MMTV murine mammary tumor virus<br />

MN micronuclei <strong>for</strong>mation<br />

MND motor neuron disease<br />

MNNG N-methyl-N'-nitro-N-nitrosoguanidine<br />

MPH morphology<br />

MRI magnetic resonance imaging<br />

mRNA messenger ribonucleic acid<br />

MROD methoxyresorufin-O-demethylase<br />

MRS magnetic resonance spectroscopy<br />

MS mass spectrometry<br />

MSCA McCarthy Scales <strong>of</strong> Children’s Abiltities<br />

mSQGQs mean sediment quality guideline quotients<br />

MT metallothionein<br />

MVV maximum voluntary ventilation<br />

MW molecular weight (e.g., high-MW, low-MW)<br />

N, n number <strong>of</strong> observations<br />

N/A not available<br />

NAAQS National Ambient <strong>Air</strong> <strong>Quality</strong> Standards<br />

NAC N-acetyl cysteine<br />

NAD nicotinamide adenine dinucleotide<br />

<strong>II</strong>-xxxv


NADH reduced nicotinamide adenine dinucleotide<br />

NADP nicotinamide adenine dinucleotide phosphate<br />

NAD(P)H, NADPH reduced nicotinamide adenine dinucleotide phosphate<br />

NADS nicotinamide adenine dinucleotide synthase<br />

NAF nafenopin<br />

NAG N-acetyl-∃-D-glucosaminidase<br />

Na-K-ATPase sodium-potassium-dependent adenosine triphosphatase<br />

NAWQA National Water-<strong>Quality</strong> Assessment<br />

NBT nitro blue tetrazolium<br />

NCBP National Contaminant Biomonitoring Program<br />

NCD nuclear chromatin decondensation (rate)<br />

NCS newborn calf serum<br />

NCTB Neurobehavioral Core Test Battery<br />

NCV nerve conduction velocity<br />

ND non-detectable; not detected<br />

NDI nuclear divison index<br />

NE norepinephrine<br />

NES Neurobehavioral Evaluation System<br />

NF-κB nuclear transcription factor-κB<br />

NGF nerve growth factor<br />

NHANES National Health and Nutrition Examination Survey<br />

NIOSH National Institute <strong>for</strong> Occupational Safety and Health<br />

NIST National Institute <strong>for</strong> Standards and Technology<br />

NK natural killer<br />

NMDA N-methyl-D-aspartate<br />

NMDAR N-methyl-D-aspartate receptor<br />

NMR nuclear magnetic resonance<br />

NO nitric oxide<br />

NO2<br />

nitrogen dioxide<br />

NO3<br />

nitrate<br />

NOAEC no-observed-adverse-effect concentration<br />

NOAEL no-observed-adverse-effect level<br />

NOEC no-observed-effect concentration<br />

NOEL no-observed-effect level<br />

NOM natural organic matter<br />

<strong>II</strong>-xxxvi


NORs nucleolar organizing regions<br />

NOS nitric oxide synthase; not otherwise specified<br />

NOx<br />

nitrogen oxides<br />

NP net productivity<br />

NPSH nonprotein sulfhydryl<br />

NR not reported<br />

NRC National Research Council<br />

NRK normal rat kidney<br />

NS nonsignificant<br />

NSAID non-steroidal anti-inflammatory agent<br />

NT neurotrophin<br />

NTA nitrilotriacetic acid<br />

O2<br />

oxygen<br />

ODVP <strong>of</strong>fspring development<br />

OH hydroxyl<br />

7-OH-coumarin 7-hydroxy-coumarin<br />

1,25-OH-D, 1,25-OH D3 1,25-dihydroxyvitamin D<br />

24,25-OH-D3<br />

24,25-dihydroxyvitamin D<br />

25-OH-D3<br />

25-hydroxyvitamin D<br />

8-OHdG 8-hydroxy-2'-deoxyguanosine<br />

O horizon <strong>for</strong>est floor<br />

OR odds ratio; other oral<br />

OSWER Office <strong>of</strong> Solid Waste and Emergency Response<br />

P, p probability value<br />

P300 event-related potential<br />

P450 1A1 cytochrome P450 1A1<br />

P450 1A2 cytochrome P450 1A2<br />

P450 CYP3a11 cytochrome P450 3a11<br />

PAD peripheral arterial disease<br />

PAH polycyclic aromatic hydrocarbon<br />

PAI-1 plasminogen activator inhibitor-1<br />

PAR population attributable risk<br />

Pb lead<br />

203<br />

Pb lead-203 radionuclide<br />

204 206 207 208<br />

Pb, Pb, Pb, Pb stable isotopes <strong>of</strong> lead-204, -206, -207, -208, respectively<br />

<strong>II</strong>-xxxvii


210 Pb lead-210 radionuclide<br />

Pb(Ac)2<br />

lead acetate<br />

PbB blood lead concentration<br />

PbCl2<br />

lead chloride<br />

Pb(ClO4)2<br />

lead chlorate<br />

PBG-S porphobilinogen synthase<br />

PBMC peripheral blood mononuclear cells<br />

Pb(NO3)2<br />

lead nitrate<br />

PbO lead oxides (or litharge)<br />

PBP progressive bulbar paresis<br />

PbS galena<br />

PbU urinary lead<br />

PC12 pheochromocytoma cell<br />

PCR polymerase chain reaction<br />

PCV packed cell volume<br />

PDE phosphodiesterase<br />

PDGF platelet-derived growth factor<br />

PDI Psychomotor Development Index<br />

PEC probable effect concentration<br />

PEF expiratory peak flow<br />

PG prostaglandin (e.g., PGE2, PGF2); prostate gland<br />

PHA phytohemagglutinin A<br />

Pi inorganic phosphate<br />

PIXE particle induced X-ray emission<br />

PKC protein kinase C<br />

pl NEpi plasma norepinephrine<br />

PMA progressive muscular atrophy<br />

PMN polymorphonuclear leucocyte<br />

PMR proportionate mortality ratio<br />

PN postnatal (day)<br />

P5N pyrimidine 5'-nucleotidase<br />

PND postnatal day<br />

p.o., PO per os (oral administration)<br />

POMS Pr<strong>of</strong>ile <strong>of</strong> Mood States<br />

ppb parts per billion<br />

<strong>II</strong>-xxxviii


ppm parts per million<br />

PPVT-R Peabody Picture Vocabulary Test-Revised<br />

PRA plasma renin activity<br />

PRL prolactin<br />

PROG progeny counts or numbers<br />

PRR prevalence rate ratio<br />

PRWT progeny weight<br />

PST percent transferrin saturation<br />

PTH parathyroid hormone<br />

PTHrP parathyroid hormone-related protein<br />

PVC polyvinyl chloride<br />

PWM pokeweed mitogen<br />

PRWT progeny weight<br />

QA/QC quality assurance/quality control<br />

Q/V flux <strong>of</strong> air (Q) divided by volume <strong>of</strong> culture (V)<br />

r Pearson correlation coefficient<br />

R 2 multiple correlation coefficient<br />

r 2 correlation coefficient<br />

226<br />

Ra most stable isotope <strong>of</strong> radium<br />

R/ALAD ratio <strong>of</strong> ALAD activity be<strong>for</strong>e and after reactivation<br />

RAVLT Rey Auditory Verbal Learning Test<br />

86<br />

Rb rubidium-86 radionuclide<br />

RBA relative bioavailablity<br />

RBC red blood cell; erythrocyte<br />

RBF renal blood flow<br />

RBP retinol binding protein<br />

RBPH reproductive behavior<br />

RCPM Ravens Colored Progressive Matrices<br />

REL rat epithelial (cells)<br />

REP<br />

reproduction<br />

RHIS reproductive organ histology<br />

222<br />

Rn most stable isotope <strong>of</strong> radon<br />

RNA ribonucleic acid<br />

ROS reactive oxygen species<br />

ROS 17.2.8 rat osteosarcoma cell line<br />

<strong>II</strong>-xxxix


RPMI 1640 Roswell Park Memorial Institute basic cell culture medium<br />

RR relative risk; rate ratio<br />

RT reaction time<br />

RSEM resorbed embryos<br />

RSUC reproductive success (general)<br />

RT reproductive tissue<br />

∑SEM sum <strong>of</strong> the molar concentrations <strong>of</strong> simultaneously extracted metal<br />

SA7 simian adenovirus<br />

SAB Science Advisory Board<br />

SAM S-adenosyl-L-methionine<br />

SBIS-4 Stan<strong>for</strong>d-Binet Intelligence Scale-4th edition<br />

s.c., SC subcutaneous<br />

SCAN Test <strong>for</strong> Auditory Processing Disorders<br />

SCE selective chemical extraction; sister chromatid exchange<br />

SCP stripping chronopotentiometry<br />

SD Spraque-Dawley (rat); standard deviation<br />

SDH succinic acid dehydrogenase<br />

SDS sodium dodecyl sulfate; Symbol Digit Substitution<br />

SE standard error; standard estimation<br />

SEM standard error <strong>of</strong> the mean<br />

SES socioeconomic status<br />

sGC soluble guanylate cyclase<br />

SH sulfhydryl<br />

SHBG sex hormone binding globulin<br />

SHE Syrian hamster embryo cell line<br />

SIMS secondary ion mass spectrometry<br />

SIR standardized incidence ratio<br />

SLP synthetic leaching procedure<br />

SM sexually mature<br />

SMAV species mean acute value<br />

SMR standardized mortality ratio<br />

SNAP Schneider Neonatal Assessment <strong>for</strong> Primates<br />

SNP sodium nitroprusside<br />

SO2<br />

sulfur dioxide<br />

SOD superoxide dismutase<br />

<strong>II</strong>-xl


SOPR sperm-oocyte penetration rate<br />

SPCL sperm cell counts<br />

SPCV sperm cell viability<br />

SQGs sediment quality guidelines<br />

SRA Self Reported Antisocial Behavior scale<br />

SRD Self Report <strong>of</strong> Delinquent Behavior<br />

SRIF somatostatin<br />

SRM Standard Reference Material<br />

SRT simple reaction time<br />

SSADMF Social Security Administration Death Master File<br />

SSB single-strand breaks<br />

SSEP somatosensory-evoked potential<br />

StAR steroidogenic acute regulatory protein<br />

STORET STOrage and RETrieval<br />

SVC sensory conduction velocity<br />

SVRT simple visual reaction time<br />

T testosterone<br />

TA tail<br />

TABL time-averaged blood lead<br />

T&E threatened and endangered (species)<br />

TAT tyrosine aminotransferase<br />

TB tibia<br />

TBARS thiobarbituric acid-reactive species<br />

TBPS Total Behavior Problem Score<br />

TCDD methionine-choline-deficient diet<br />

T cell T lymphocyte<br />

TCLP toxic characteristic leaching procedure<br />

TE testes<br />

TEC threshold effect concentration<br />

TEDG testes degeneration<br />

TEL tetraethyl lead<br />

TES testosterone<br />

TEWT testes weight<br />

TF transferrin, translocation factor<br />

TG 6-thioguanine<br />

<strong>II</strong>-xli


TGF trans<strong>for</strong>ming growth factor<br />

TH tyrosine hydroxylase<br />

232 Th stable isotope <strong>of</strong> thorium-232<br />

TLC Treatment <strong>of</strong> <strong>Lead</strong>-exposed Children (study)<br />

TNF tumor necrosis factor (e.g., TNF-α)<br />

TOF time-<strong>of</strong>-flight<br />

tPA plasminogen activator<br />

TPRD total production<br />

TRH thyroid releasing hormone<br />

TRV toxicity reference value<br />

TSH thyroid stimulating hormone<br />

TSP triple-super phosphate<br />

TT3 total triiodothyronine<br />

TT4 serum total thyroxine<br />

TTES total testosterone<br />

TTR transthyretin<br />

TU toxic unit<br />

TWA time-weighted average<br />

TX tromboxane (e.g., TXB2)<br />

U uriniary<br />

235 238<br />

U, U uranium-234 and -238 radionuclides<br />

UCP urinary coproporphyrin<br />

UDP uridine diphosphate<br />

UNECE United Nations Economic Commission <strong>for</strong> Europe<br />

Ur urinary<br />

<strong>US</strong>FWS U.S. Fish and Wildlife Service<br />

<strong>US</strong>GS United States Geological Survey<br />

UV ultraviolet<br />

V79 Chinese hamster lung cell line<br />

VA Veterans Administration<br />

VC vital capacity; vitamin C<br />

VDR vitamin D receptor<br />

VE vitamin E<br />

VEP visual-evoked potential<br />

VI variable-interval<br />

<strong>II</strong>-xlii


vit C vitamin C<br />

vit E vitamin E<br />

VMA vanilmandelic acid<br />

VMI Visual-Motor Integration<br />

VSM vascular smooth muscle (cells)<br />

VSMC vascular smooth muscle cells<br />

WAIS Wechsler Adult Intelligence Scale<br />

WDS wavelength dispersive spectrometers<br />

WHO World Health Organization<br />

WISC Wechsler Intelligence Scale <strong>for</strong> Children<br />

WISC-R Wechsler Intelligence Scale <strong>for</strong> Children-Revised<br />

WO whole organism<br />

WRAT-R Wide Range Achievement Test-Revised<br />

WT wild type<br />

WTHBF-6 human liver cell line<br />

ww wet weight<br />

XAFS X-ray absorption fine structure<br />

XANES X-ray absorption near edge spectroscopy<br />

XAS X-ray absorption spectroscopy<br />

XPS X-ray photoelectron spectroscopy<br />

X-rays synchrotron radiation<br />

XRD X-ray diffraction<br />

XRF X-ray fluorescence<br />

ZAF correction in reference to three components <strong>of</strong> matrix effects:<br />

atomic number (Z), absorption (A), and fluorescence (F)<br />

ZnNa2 DTPA zinc disodium diethylenetriaminepentaacetic acid<br />

ZnNa2 EDTA zinc disodium ethylenediaminetetraacetic acid<br />

ZPP zinc protoporphyrin<br />

<strong>II</strong>-xliii


AX7. CHAPTER 7 ANNEX - ENVIRONMENTAL<br />

EFFECTS OF LEAD<br />

AX7.1 TERRESTRIAL ECOSYSTEMS<br />

AX7.1.1 Methodologies Used in Terrestrial Ecosystems Research<br />

The distribution <strong>of</strong> Pb throughout the terrestrial ecosystem, via aerial deposition, has been<br />

discussed throughout this document. Its further impacts on soil, sediment, and water provide<br />

numerous pathways that may promote unacceptable risk to all levels <strong>of</strong> biota. Stable isotopes <strong>of</strong><br />

Pb have been found useful in identifying sources and apportionment to various sources. One <strong>of</strong><br />

the key factors affecting assessment <strong>of</strong> risk is an understanding, and perhaps quantification, <strong>of</strong><br />

bioavailability. There<strong>for</strong>e, the bioavailability <strong>of</strong> Pb is a key issue to the development <strong>of</strong><br />

NAAQS. However, the discussion <strong>of</strong> all methods used in characterizing bioavailability is<br />

beyond the scope <strong>of</strong> this chapter. The following topics are discussed in this chapter.<br />

• <strong>Lead</strong> Isotopes and Apportionment<br />

• Methodologies to determine Pb speciation<br />

• <strong>Lead</strong> and the Biotic Ligand Model (BLM)<br />

• In situ methods to reduce Pb bioavailability<br />

AX7.1.1.1 <strong>Lead</strong> Isotopes and Apportionment<br />

Determination <strong>of</strong> the extent <strong>of</strong> Pb contamination from an individual source(s) and its<br />

impact are <strong>of</strong> primary importance in risk assessment. The identification <strong>of</strong> exposure pathway(s)<br />

is fundamental to the risk analysis and critical in the planning <strong>of</strong> remediation scenarios.<br />

Although societies have been consuming Pb <strong>for</strong> nearly 9,000 years, production <strong>of</strong> Pb in<br />

the United States peaked in 1910 and 1972, at approximately 750 and 620 kt/year, respectively<br />

(Rabinowitz, 2005). The diversity <strong>of</strong> potential Pb sources (fossil fuel burning, paint pigments,<br />

gasoline additives, solders, ceramics, batteries) and associated production facilities (mining,<br />

milling, smelting-refining) make fingerprinting <strong>of</strong> sources difficult. (See Chapter 2 and its<br />

Annex <strong>for</strong> additional in<strong>for</strong>mation on sources.) There<strong>for</strong>e, dealing with multiple sources (point<br />

and nonpoint), a reliable and specific fingerprinting technique is required. It has been well<br />

established (Sturges and Barrie, 1987; Rabinowitz, 1995) that the stable isotope composition <strong>of</strong><br />

AX7-1


Pb is ideally suited <strong>for</strong> this task. <strong>Lead</strong> isotopic ratio differences <strong>of</strong>ten allow multiple sources to<br />

be distinguished, with an apportionment <strong>of</strong> the bulk Pb concentration made to those sources.<br />

<strong>Lead</strong> has four stable isotopes: 204 Pb, 206 Pb, 207 Pb, and 208 Pb in natural abundances <strong>of</strong> 1.4,<br />

24.1, 22.1, and 52.4%, respectively. The radiogenic 206 Pb, 207 Pb, and 208 Pb are produced by<br />

radioactive decay <strong>of</strong> 238 U, 235 U, and 232 Th, respectively. Thus, the isotopic composition <strong>of</strong> Pb<br />

varies based on the U:Pb and Th:Pb ratios <strong>of</strong> the original ore’s source and age (Faure, 1977).<br />

Because <strong>of</strong> the small fractional mass differences <strong>of</strong> the Pb isotopes, ordinary chemical and<br />

pyrometallurgical reactions will not alter their original composition. There<strong>for</strong>e, anthropogenic<br />

sources reflect the isotopic composition <strong>of</strong> the ores from which the Pb originated.<br />

To acquire the Pb isotopes, a sample, generally in aqueous <strong>for</strong>m, is analyzed on an<br />

ICP/MS (quadrapole, magnetic sector, or time-<strong>of</strong>-flight). Studies reviewing the most common<br />

analytical and sample preparation procedures include Ghazi and Millette (2004), Townsend et al.<br />

(1998), and Encinar et al. (2001a,b). The correction factor <strong>for</strong> mass discrimination biases is<br />

generally made by analyzing the National Institute <strong>for</strong> Standards and Technology (NIST),<br />

Standard Reference Material (SRM) 981 and/or spiked 203 Tl and 205 Tl isotopes (Ketterer et al.,<br />

1991; Begley and Sharp, 1997). The overall success <strong>of</strong> Pb isotope fingerprinting is generally<br />

dependent on analysis precision, which in turn depends on the type <strong>of</strong> mass analyzer used<br />

(Table AX7-1.1.1).<br />

Table AX7-1.1.1. Relative Standard Deviation (RSD) <strong>for</strong> <strong>Lead</strong> Isotope<br />

Ratios on Selected Mass Spectrometers<br />

Single-Focusing<br />

High-Resolution<br />

Magnetic Sector<br />

RSD Quadrapole Double-Focusing Magnetic Sector<br />

ICP/MS<br />

204 206<br />

Pb: Pb 0.0031 0.0032 0.00053 0.0011<br />

207 Pb: 206 Pb 0.0032 0.0027 0.00053 0.00048<br />

208 Pb: 206 Pb 0.0026 0.0024 0.00053 0.00046<br />

An extensive database comprising primarily North American Pb sources can be assembled<br />

from Doe and Rohrbough (1977), Doe and Stacey (1974), Doe et al. (1968), Heyl et al. (1974),<br />

AX7-2


Leach et al. (1998), Stacey et al. (1968), Zartman (1974), Cannon and Pierce (1963), Graney<br />

et al. (1996), Unruh et al. (2000), James and Henry (1993), Rabinowitz (2005), and<br />

Small (1973).<br />

The use <strong>of</strong> Pb isotopes to quantitatively apportion source contributions follows the simple<br />

mixing rule when only two sources are possible (Faure, 1977). Once multiple sources need to be<br />

considered, a unique solution can no longer be calculated (Fry and Sherr, 1984). Phillips and<br />

Gregg (2003) have designed a model to give feasible source contributions when multiple sources<br />

are likely. Many studies have demonstrated the usefulness <strong>of</strong> this apportionment technique.<br />

Media <strong>of</strong> all types have been studied: water (Flegal et al., 1989a,b; Erel et al., 1991; Monna<br />

et al., 1995), ice (Planchon et al., 2002), dust (Adgate et al., 1998; Sturges et al., 1993), and<br />

soil/sediments (Hamelin et al., 1990; Farmer et al., 1996; Bindler et al., 1999; Haack et al., 2004;<br />

Rabinowitz and Wetherill, 1972; Rabinowitz, 2005; Ketterer et al., 2001).<br />

AX7.1.1.2 Speciation in Assessing <strong>Lead</strong> Bioavailability in the Terrestrial Environment<br />

One <strong>of</strong> the three processes defined by the National Research Council in its review on<br />

bioavailability (NRC, 2002) is “contaminant interactions between phases”, more commonly<br />

referred to as “speciation.”<br />

A wide variety <strong>of</strong> analytical (XRD, EPMA, EXAFS, PIXE, XPS, XAS, SIMS) and<br />

chemical speciation modeling (SOILCHEM, MINTEQL, REDEQL2, ECOSAT, MINTEQA2,<br />

HYDRAQL, PHREEQE, WATEQ4F) tools have been used to characterize a metal’s speciation<br />

as it is found in various media. Currently, <strong>for</strong> risk assessment purposes (not considering<br />

phytotoxicity), where large sites with numerous media, pathways, and metals must <strong>of</strong>ten be<br />

characterized in a reasonable time frame, electron microprobe analysis (EMPA) techniques<br />

provide the greatest in<strong>for</strong>mation on metal speciation. Other techniques such as extended X-ray<br />

absorption fine structure (EXAFS) and extended X-ray absorption near edge spectroscopy<br />

(EXANES) show great promise and will be important in solving key mechanistic questions.<br />

In the case <strong>of</strong> phytotoxicity, the speciation <strong>of</strong> metals by direct measurement or chemical models<br />

<strong>of</strong> pore-water chemistry is most valuable. Further work needs to be done in developing<br />

analytical tools <strong>for</strong> the speciation <strong>of</strong> the methyl-<strong>for</strong>ming metals (Hg, As, Sb, Se, and Sn) in soils<br />

and sediments.<br />

AX7-3


Concept<br />

For a given metal or metalloid (hereafter referred to as metal), the term speciation refers<br />

to its chemical <strong>for</strong>m or species, including its physicochemical characteristics that are relevant to<br />

bioavailability. As a result <strong>of</strong> the direct impact these factors <strong>of</strong>ten have on a metal’s<br />

bioavailability, the term “bioaccessibility” has been adopted to define those factors.<br />

Speciation Role<br />

The accumulation <strong>of</strong> metals in the lithosphere is <strong>of</strong> great concern. Unlike organic<br />

compounds, metals do not degrade and, thus, have a greater tendency to bioaccumulate. It is<br />

now well accepted that knowledge <strong>of</strong> the bulk, toxic characteristic leaching procedure (TCLP),<br />

or synthetic leaching procedure (SLP) concentrations <strong>for</strong> any metal is not a controlling factor in<br />

understanding a metal’s environmental behavior or in developing remedies <strong>for</strong> its safe<br />

management. Although these tests are essential to site characterization and management, they<br />

<strong>of</strong>fer no insight into risk assessment. Rather, it is the metal’s bioavailability (the proportion <strong>of</strong> a<br />

toxin that passes a physiological membrane [the plasma membrane in plants or the gut wall in<br />

animals] and reaches a target receptor [cytosol or blood]), which plays a significant role in the<br />

risk assessment <strong>of</strong> contaminated media.<br />

The NRC review (NRC, 2002) on bioavailability defined bioavailability processes in<br />

terms <strong>of</strong> three key processes:<br />

• contaminant interactions between phases (association-dissociation/bound-released),<br />

• transport <strong>of</strong> contaminants to organism, and<br />

• passage across a physiological membrane.<br />

As mentioned previously, the first process is more commonly referred to as speciation.<br />

The speciation <strong>of</strong> a toxic metal in the environment is a critical component <strong>of</strong> any ecosystem<br />

health risk assessment. Four important toxicologic and toxicokinetic determinants relating<br />

speciation to bioavailability are the (1) chemical <strong>for</strong>m or species, (2) particle size <strong>of</strong> the metal<br />

<strong>for</strong>m, (3) lability <strong>of</strong> the chemical <strong>for</strong>m, and (4) source.<br />

AX7-4


Chemical Form <strong>of</strong> Species<br />

The solid phase in a medium controls the activity <strong>of</strong> a metal in solution, whether the<br />

solution is surface, ground, or pore water or GI fluids, and plays a pr<strong>of</strong>ound role in metal<br />

bioavailability. This is perhaps best illustrated by in vivo and in vitro results <strong>for</strong> many <strong>of</strong> the<br />

common Pb-bearing minerals (Drexler, 1997) (Figure AX7-1.1.1). The metal species found in<br />

media are <strong>of</strong>ten diverse, and data suggest that their bioavailability may be significantly<br />

influenced by site-specific variations within these identified metal species (Davis et al., 1993;<br />

Ruby et al., 1992; Drexler and Mushak, 1995).<br />

Figure AX7-1.1.1. Relationship <strong>of</strong> bioaccessibility (low, medium, high) versus speciation<br />

as shown with scanning electron micrographs <strong>of</strong> various Pb-bearing<br />

materials.<br />

Particle Size <strong>of</strong> Metal Species<br />

Particle size <strong>of</strong> a metal <strong>for</strong>m is an important factor in the mobilization <strong>of</strong> the metal,<br />

primarily because as size decreases, the surface area <strong>of</strong> the particle increases, thereby increasing<br />

solubility. Thus, although solubility is not the only control <strong>for</strong> bioavailability, an increase in<br />

bioavailability has been directly attributed to a decrease in particle size: Barltrop and Meek<br />

AX7-5


(1979) observed that “the smaller the lead particle, the higher blood lead level.” Similar<br />

observations were made by Healy et al. (1992) using and an in vitro dissolution technique.<br />

Drexler (1997) presented in vitro results on numerous Pb-bearing phases ranging in particle size<br />

from 35 to 250 µm. While all phases studied showed increased bioavailability with decreasing<br />

particle size, more significantly, not all <strong>for</strong>ms showed the same degree or magnitude <strong>of</strong> change<br />

(Figure AX7-1.1.2). Atmospheric particles are generally found to occur in bimodal populations:<br />

fine; 0.1 to 2.5 µm and coarse; 2.5 to 15 µm. This distribution is both a function <strong>of</strong> there<br />

transport mechanism and emission source. Although the upper size limit <strong>for</strong> particles that can be<br />

suspended in air is about 75 µm (Cowherd et al., 1974), other means <strong>of</strong> mechanical entrainment<br />

(saltation, and creep) can transport particles as large as 1000 µm, supporting the importance <strong>of</strong><br />

fugative emissions on media contamination. In addition, particle size can change post<br />

depositional, as soluble <strong>for</strong>ms re-precipitate or sorb onto other surfaces. Limited data are<br />

available on the particle-size <strong>of</strong> discrete Pb phases from multimedia environments. One example<br />

is the study by Drexler, 2004 at Herculaneum, Missouri. At this site, galena (PbS) was the<br />

dominant Pb species with mean particle-size distributions <strong>of</strong> 4, 6, and 14 µm in PM10 filters,<br />

house dust, and soils, respectively. These findings support the conclusion that aerial transport<br />

was the primary mechanism <strong>for</strong> Pb deposition in residential yards. Finally, such laboratory data<br />

have been supported by extensive epidemiologic evidence, en<strong>for</strong>cing the importance <strong>of</strong> particle<br />

size (Bornschein et al., 1987; Brunekreef et al., 1983; Angle et al., 1984).<br />

Particle Lability<br />

The impact on bioavailability <strong>of</strong> a metal particle’s lability (its associations within the<br />

medium matrix) is not well documented, but it follows the premise put <strong>for</strong>th by many <strong>of</strong> the<br />

developing treatment technologies regarding its being bound or isolated from its environment.<br />

Data from several <strong>EPA</strong> Superfund sites and the Region V<strong>II</strong>I swine study (U.S. Environmental<br />

Protection Agency, 2004a) suggest that matrix associations, such as liberated versus enclosed,<br />

can play an important part in bioavailability. As illustrated in Figure AX7-1.1.3, two different<br />

media with similar total Pb concentrations and Pb <strong>for</strong>ms (slag, Pb-oxide, and Pb-arsenate)<br />

exhibit significantly different bioavailabilities. In the Murray, UT sample (bioaccumulation<br />

factor [BAF] = 53%), a greater fraction <strong>of</strong> the more bioavailable Pb-oxides are liberated and<br />

not enclosed in the less-soluble glass-like slag as observed in the <strong>Lead</strong>ville, CO sample<br />

AX7-6


Figure AX7-1.1.2. Variation <strong>of</strong> bioavailability with particle size.<br />

(BAF = 17%). Other evidence is more empirical, as illustrated in Figure AX7-1.1.4, where a<br />

large particle <strong>of</strong> native Pb is shown to have developed a weathering ring <strong>of</strong> highly bioavailable<br />

Pb-chloride and Pb-oxide. Such observations can be useful in understanding the mechanistic<br />

phenomena controlling bioavailability. In addition, they will aid in developing and validating<br />

models to predict metal-environment interactions.<br />

AX7-7


Figure AX7-1.1.3. Illustration <strong>of</strong> particle lability and bioavailability at two different sites<br />

with similar total Pb concentrations and Pb <strong>for</strong>ms.<br />

Figure AX7-1.1.4. Scanning electron micrograph <strong>of</strong> a large native Pb particle showing<br />

outer ring <strong>of</strong> highly bioavailable Pb-chloride and Pb-oxide.<br />

AX7-8


Source<br />

Although the source <strong>of</strong> a metal is not directly related to bioavailability, it plays an<br />

important role in risk assessment with the evaluation <strong>of</strong> metal (1) pathways, (2) background,<br />

and (3) apportionment. It is important to understand a metal’s pathway be<strong>for</strong>e any remedial<br />

action can be taken; otherwise, recontamination <strong>of</strong> the primary pathway and reexposure can<br />

occur. Knowledge <strong>of</strong> background is important, as an action level cannot be established below<br />

natural background levels.<br />

Plants<br />

When considering the bioavailability <strong>of</strong> a metal to plants from soils and sediments, it is<br />

generally assumed that both the kinetic rate <strong>of</strong> supply and the speciation <strong>of</strong> the metal to either the<br />

root or shoot are highly important. In soils and sediments generally, only a small volume <strong>of</strong><br />

water is in contact with the chemical <strong>for</strong>m, and although the proportion <strong>of</strong> a metal’s<br />

concentration in this pore water to the bulk soil/sediment concentration is small, it is this phase<br />

that is directly available to plants. There<strong>for</strong>e, pore water chemistry (i.e., metal concentration as<br />

simple inorganic species, organic complexes, or colloid complexes) is most important.<br />

Tools currently used <strong>for</strong> metal speciation <strong>for</strong> plants include (1) in-situ measurements<br />

using selective electrodes (Gundersen et al., 1992; Archer et al., 1989; Wehrli et al., 1994);<br />

(2) in-situ collection techniques using diffusive equilibrium thin films (DET) and diffusive<br />

gradient thin films (DGT) followed by laboratory analyses (Davison et al., 1991, 1994; Davison<br />

and Zhang, 1994; Zhang et al., 1995); and (3) equilibrium models ( SOILCHEM) (Sposito and<br />

Coves, 1988).<br />

AX7.1.1.3 Tools <strong>for</strong> Bulk <strong>Lead</strong> Quantification and Speciation<br />

Bulk Quantification<br />

The major analytical methods most commonly used <strong>for</strong> bulk analyses outlined in the 1986<br />

<strong>Lead</strong> ACQD included:<br />

• Atomic Absorption Spectrometry (AAS)<br />

• Emission Spectrometry (Inductively coupled plasma/atomic emission spectrometry)<br />

• X-ray Fluorescence (XRF)<br />

• Isotope Dilution Mass Spectrometry (ID/MS)<br />

AX7-9


• Colorimetric<br />

• Electrochemical (anodic stripping voltametry and differential pulse polarography).<br />

The choice <strong>of</strong> analytical method today <strong>for</strong> bulk quantification is generally ICP/AES or<br />

ICP/MS (U.S. Environmental Protection Agency, 2001). Since 1986, numerous SRMs have<br />

been developed <strong>for</strong> Pb (Table AX7-1.1.2), and several significant technological improvements<br />

have been developed.<br />

Table AX7-1.1.2. National Institute <strong>of</strong> Standards and Technology <strong>Lead</strong> SRMs<br />

NIST SRM Medium<br />

Mean Pb<br />

mg/kg<br />

2710 Soil 5532<br />

2711 Soil 1162<br />

2709 Soil 18.9<br />

2587 Soil (paint) 3242<br />

2586 Soil (paint) 432<br />

2783 Filter (PM2.5) 317<br />

1648 Urban particulate 6550<br />

1649a Urban dust 12,400<br />

2584 Indoor dust 9761<br />

2583 Indoor dust 85.9<br />

1515 Apple leaves 0.47<br />

1575 Pine needles 0.167<br />

Modern spectrometry systems have replaced photomultiplier tubes with a charge-coupled<br />

device (CCD). The CCD is a camera that can detect the entire light spectrum (>70,000 lines)<br />

from 160 to 785 nm. This allows <strong>for</strong> the simultaneous measurement <strong>of</strong> all elements, as well as<br />

any interfering lines (a productivity increase), and increases precision. The detection limit <strong>for</strong> Pb<br />

in clean samples can now be as low as 40 ppb.<br />

AX7-10


Modern ICP/AES systems <strong>of</strong>fer a choice <strong>of</strong> either axial viewed plasma (horizontal),<br />

which provides greater sensitivity (DL= 0.8 µg Pb/L), or radial (vertical) viewed plasma, which<br />

per<strong>for</strong>ms best with high total dissolved samples (DL = 5.0 µg Pb/L).<br />

The development <strong>of</strong> reaction or collision cells have expanded the capabilities <strong>of</strong> ICP/MS<br />

and lowered detection limits <strong>for</strong> many elements that were difficult to analyze because <strong>of</strong><br />

interferences such as Se, As, Ti, Zn, Ca, Fe, and Cr. The cells provide efficient interference<br />

(isobaric, polyatomic, and argide) removal independent <strong>of</strong> the analyte and sample matrix by<br />

using various reaction gases (H2, He, NH3), eliminating the need <strong>for</strong> interference correction<br />

equations.<br />

Speciation Tools<br />

A wide variety <strong>of</strong> analytical and chemical techniques have been used to characterize a<br />

metal’s speciation (as defined above) in various media (Hunt et al., 1992; Manceau et al., 1996,<br />

2000a; Welter et al., 1999; Szulczewski et al., 1997; Isaure et. al., 2002; Lumsdon and Evans,<br />

1995; Gupta and Chen, 1975; Ma and Uren, 1995; Charlatchka et al., 1997). Perhaps the most<br />

important factor that one must keep in mind in selecting a technique is that, when dealing with<br />

metal-contaminated media, one is most <strong>of</strong>ten looking <strong>for</strong> the proverbial “needle in a haystack.”<br />

There<strong>for</strong>e, the speciation technique must not only provide the in<strong>for</strong>mation outlined above, but it<br />

must also determine that in<strong>for</strong>mation from a medium that contains very little <strong>of</strong> the metal.<br />

As illustrated in Figure AX7-1.1.5, <strong>for</strong> a Pb-contaminated soil, less than 1% (modally) <strong>of</strong> a<br />

single species can be responsible <strong>for</strong> a bulk metal’s concentration above an action level. This<br />

factor is even more significant <strong>for</strong> other metals (i.e., As, Cd, or Hg) were action levels are <strong>of</strong>ten<br />

below 100 mg/kg.<br />

Of the techniques tested (physicochemical, extractive, and theoretical), the tools that have<br />

been used most <strong>of</strong>ten to evaluate speciation <strong>for</strong> particle-bound metal include X-ray absorption<br />

spectroscopy (XAS), X-ray diffraction (XRD), particle induced X-ray emission (PIXE and<br />

µPIXE), electron probe microanalysis (EPMA), secondary ion mass spectrometry (SIMS),<br />

X-ray photoelectron spectroscopy (XPS), sequential extractions, and single chemical extractions.<br />

The tools that have been used most <strong>of</strong>ten to evaluate speciation <strong>for</strong> metal particles in solution<br />

include the following computer-based models: MINTEQL, REDEQL2, ECOSAT, MINTEQA2,<br />

HYDRAQL, PHREEQE, and WATEQ4F. These tools are briefly described below.<br />

AX7-11


Figure AX7-1.1.5. Bulk lead versus single species modality. Shaded area represents<br />

typical soil-lead concentrations found at remediation sites in the<br />

western United States.<br />

Particle-Bound Metal<br />

Direct Approaches<br />

Over the past decade, numerous advances in materials science have led to the<br />

development <strong>of</strong> a wide range in analytical tools <strong>for</strong> the determination <strong>of</strong> metal concentration,<br />

bonding, and valance <strong>of</strong> individual particles on a scale that can be considered useful <strong>for</strong> the<br />

speciation <strong>of</strong> environmentally important materials (i.e., soils, wastes, sediments, and dust).<br />

This review will provide the reader with a brief description <strong>of</strong> these techniques, including their<br />

benefits, limitations (cost, availability, sample preparation, resolution), and usability as well as<br />

references to current applications. Although most <strong>of</strong> these tools are scientifically sound and<br />

<strong>of</strong>fer important in<strong>for</strong>mation on the mechanistic understanding <strong>of</strong> metal occurrence and behavior,<br />

only a few currently provide useful in<strong>for</strong>mation on metal bioavailability at a “site” level.<br />

However, one may still find other techniques essential to a detailed characterization <strong>of</strong> a selected<br />

AX7-12


material to describe the chemical or kinetic factors controlling a metal’s release, transport,<br />

and/or exposure.<br />

X-Ray absorption Spectroscopy (XAS). X-ray absorption spectroscopy (XAS) is a<br />

powerful technique using the tunable, monochromatic (white light) X-rays produced by a<br />

synchrotron (2-4 GeV) to record oscillations in atomic absorption within a few 100 GeV <strong>of</strong> an<br />

element’s absorption edge. Spectra provide in<strong>for</strong>mation on both chemical state and atomic<br />

structure. Measurements are theoretically available <strong>for</strong> all elements and are not surface-sensitive<br />

nor sample-sensitive (i.e., gases, liquids, solids, and amorphous materials are testable).<br />

High-energy spectra within 30 eV <strong>of</strong> the edge, termed XANES (X-ray absorption near<br />

edge structure spectroscopy (Fendorf et al., 1994; Maginn, 1998), are particularly suited <strong>for</strong><br />

determination and quantification (10 to 100 ppm) <strong>of</strong> metal in a particular oxidation state<br />

(Szulczewski et al., 1997; Shaffer et al., 2001; Dupont et al., 2002). The lower-energy spectra<br />

persist some 100 eV above the edge. These oscillations are termed EXAFS (extended X-ray<br />

absorption fine structure) and are more commonly used <strong>for</strong> speciation analyses (Welter et al.,<br />

1999; Manceau et al., 1996, 2000a; Isaure et al., 2002).<br />

The main limitations to XAS techniques are (1) the lack <strong>of</strong> spatial resolution; (2) XAS<br />

techniques provide only a weighted average signal <strong>of</strong> structural configurations, providing<br />

in<strong>for</strong>mation on the predominant <strong>for</strong>m <strong>of</strong> the metal, while minor species, which may be more<br />

bioavailable, can be overlooked; (3) access to synchrotrons is limited and the beam time required<br />

to conduct a site investigation would be prohibitive; (4) a large spectral library must be<br />

developed; (5) generally, poor fits to solution models are achieved when the compound list is<br />

large; and (6) high atomic number elements have masking problems based on compound density.<br />

X-Ray Diffraction (XRD). In X-ray diffraction, a monochromatic Fe, Mo, Cr, Co, W, or<br />

Cu X-ray beam rotates about a finely powdered sample and is reflected <strong>of</strong>f the interplanar<br />

spacings <strong>of</strong> all crystalline compounds in the sample, fulfilling Bragg’s law (nλ = 2dsinθ). The<br />

identification <strong>of</strong> a species from this pattern is based upon the position <strong>of</strong> the lines (in terms <strong>of</strong><br />

θ or 2θ) and their intensities as recorded by an X-ray detector. The diffraction angle (2θ) is<br />

determined by the spacing between a particular set <strong>of</strong> atomic planes. Identification <strong>of</strong> the species<br />

is empirical, and current available databases contain more than 53,000 compounds.<br />

If a sample contains multiple compounds, interpretation becomes more difficult and<br />

computer-matching programs are essential. In some instances, by measuring the intensity <strong>of</strong> the<br />

AX7-13


diffraction lines and comparing them to standards, it is possible to quantitatively analyze<br />

crystalline mixtures; however, if the species is a hydrated <strong>for</strong>m or has a preferred orientation,<br />

this method is only semiquantitative at best. Since this technique represents a bulk analysis,<br />

no particle size or lability in<strong>for</strong>mation can be extracted from the patterns.<br />

Particle Induced X-Ray Emission (PIXE and µPIXE). Particle induced X-ray emission<br />

(PIXE) uses a beam, ~4 µm in diameter, <strong>of</strong> heavy charged particles (generally He) to irradiate<br />

the sample. The resulting characteristic X-rays are emitted and detected in a similar manner as<br />

XRF, using Si-Li detectors. Particles generated from a small accelerator or cyclotron, with a<br />

potential <strong>of</strong> 2 to 4 MeV, are commonly used. Detection limits on the order <strong>of</strong> 1 mg/kg are<br />

achieved on thin-film samples. Disadvantages to its use <strong>for</strong> speciation include (1) only a small<br />

volume <strong>of</strong> material can be analyzed (1 to 2 mg/cm 2 ); (2) no particle size in<strong>for</strong>mation is provided;<br />

(3) peak overlaps associated with Si-Li detectors limit identification <strong>of</strong> species; (4) limited<br />

availability; and (5) high cost. For a further review <strong>of</strong> PIXE analysis and applications, see<br />

Maenhaut (1987).<br />

Electron Probe Microanalysis (EPMA). Electron probe microanalysis uses a finely<br />

focused (1 µm) electron beam (generated by an electron gun operating at a 2 to 30 kV<br />

accelerating voltage and pico/nanoamp currents) to produce a combination <strong>of</strong> characteristic<br />

X-rays <strong>for</strong> elemental quantification along with secondary electrons and/or backscatter electrons<br />

<strong>for</strong> visual inspection <strong>of</strong> a sample. Elements from beryllium to uranium can be nondestructively<br />

analyzed at the 50-ppm level with limited sample preparation. X-ray spectra can be rapidly<br />

acquired using either wavelength dispersive spectrometers (WDS) or energy dispersive<br />

spectrometers (EDS).<br />

With WDS, a set <strong>of</strong> diffracting crystals, <strong>of</strong> known d-spacing, revolve in tandem with a<br />

gas-filled proportional counter inside the spectrometer housing so that Bragg’s law is satisfied<br />

and a particular wavelength can be focused. Photon energy pulses reflecting <strong>of</strong>f the crystal are<br />

collected <strong>for</strong> an individual elemental line by the counter as a first approximation to<br />

concentration. For quantitative analysis, these intensities are compared to those <strong>of</strong> known<br />

standards and must be corrected <strong>for</strong> background, dead time, and elemental interactions (ZAF)<br />

(Goldstein et al., 1992). ZAF correction is in reference to the three components <strong>of</strong> matrix<br />

effects: atomic number (Z), absorption (A), and fluorescence (F).<br />

AX7-14


With EDS, a single Si-Li crystal detector is used in conjunction with a multichannel<br />

analog-digital converter (ADC) to sort electrical pulses (with heights approximately proportional<br />

to the quantum energy <strong>of</strong> the photon that generated them), producing a spectrum <strong>of</strong> energy<br />

(wavelength) versus counts. The net area under a particular peak (elemental line) is proportional<br />

to its concentration in the sample. For quantitative analyses, corrections similar to WDS analysis<br />

must be per<strong>for</strong>med. Although EDS detectors are more efficient than WDS, detection limits are<br />

significantly greater (~1000 ppm), because <strong>of</strong> elevated backgrounds and peak overlaps.<br />

For speciation analysis, the EDS system must NEVER be used as the primary detector, as<br />

numerous errors in species identification are <strong>of</strong>ten made. These are generally the result <strong>of</strong><br />

higher-order X-ray line overlaps.<br />

This technique has been routinely used <strong>for</strong> site characterizations (Linton et al., 1980;<br />

Hunt et al., 1992; Camp, Dresser, and McKee (CDM), 1994; U.S. Environmental Protection<br />

Agency, 2002). Currently this technique <strong>of</strong>fers the most complete data package on metal<br />

speciation than any <strong>of</strong> the other tools. The method is relatively fast and inexpensive, available,<br />

and provides all <strong>of</strong> the required in<strong>for</strong>mation <strong>for</strong> bioavailability assessments (i.e., particle size,<br />

species, lability, and sourcing). A number <strong>of</strong> limitations still need to be addressed including:<br />

(1) its inability to quickly isolate a statistically significant population <strong>of</strong> particles in soils with<br />

low bulk metal concentrations (


The major disadvantage <strong>of</strong> SIMS to species identification is that each element or isotope<br />

must be tuned and analyzed sequentially. This makes the identification <strong>of</strong> a metal <strong>for</strong>m highly<br />

time-consuming and, thus, the characterization <strong>of</strong> a multiphase medium impractical.<br />

X-Ray Photoelectron Spectroscopy (XPS). X-ray photoelectron spectroscopy or ESCA<br />

(electron spectroscopy <strong>for</strong> chemical analysis, as it was previously known) is a classical surface,<br />

10 to 50 Å in depth, analytical technique <strong>for</strong> determining qualitative elemental concentrations <strong>of</strong><br />

elements greater than He in atomic number and provides limited structural and oxidation state<br />

in<strong>for</strong>mation. In XPS, the high-energy (15 kV) electrons are typically produced from a dualanode<br />

(Al-Mg) X-ray tube. The excitation or photoionization <strong>of</strong> atoms within the near surface <strong>of</strong><br />

the specimen emit a spectrum <strong>of</strong> photoelectrons. The measured binding energy is characteristic<br />

<strong>of</strong> the individual atom to which it was bound. Monochromatic sources are <strong>of</strong>ten employed to<br />

improve energy resolution, allowing one to infer oxidation states <strong>of</strong> elements or structure <strong>of</strong><br />

compounds (organic and inorganic) by means <strong>of</strong> small chemical shifts in binding energies<br />

(Hercules, 1970). The major disadvantages <strong>of</strong> XPS <strong>for</strong> environmental speciation studies is its<br />

poor sensitivity, especially in complex matrices and its large, 100-200 µm, spatial resolution.<br />

The direct speciation techniques discussed above are summarized in Table AX7-1.1.3.<br />

Indirect Approaches<br />

A more indirect approach to speciation than the methods previously described include the<br />

functional or operational extraction techniques that have been used extensively over the years<br />

(Tessier et al., 1979; Tessier and Campbell, 1988; Gupta and Chen, 1975). These methods use<br />

either a single or sequential extraction procedure to release species associated with a particular<br />

metal within the media. Single chemical extractions are generally used to determine the<br />

bioavailable amount <strong>of</strong> metal in a functional class: water-soluble, exchangeable, organically<br />

bound, Fe-Mn bound, or insoluble.<br />

In a similar approach, sequential extractions treat a sample with a succession <strong>of</strong> reagents<br />

intended to specifically dissolve different, less available phases. Many <strong>of</strong> these techniques have<br />

been proposed, most <strong>of</strong> which are a variation on the classical method <strong>of</strong> Tessier et al. (1979),<br />

in which metal associated with exchangeable, carbonate-bound, Fe-Mn bound, organically<br />

bound, and residual species can be determined. Beckett (1989), Kheboian and Bauer (1987),<br />

and Foerstner (1987) provide excellent reviews on the use and abuse <strong>of</strong> extractions. These<br />

AX7-16


AX7-17<br />

Tools Species Lability<br />

Species Particle<br />

Size<br />

Table AX7-1.1.3. Characteristics <strong>for</strong> Direct Speciation Techniques<br />

Species Valance<br />

State<br />

Species Bonding<br />

Species<br />

Composition<br />

Species<br />

Abundance<br />

XRD No No No No No# No No No 3-4 vol% Bulk 1 $<br />

EMPA Yes Yes Yes+ No Yes Yes? B-U No*** 50 ppm 0.5-1 µm 2 $$<br />

SIMS No Yes No No Yes* Yes** Li-U Yes 1 ppb 10 µm 4 $$$<br />

XPS No No Yes Yes Yes* Yes** H-U No wt.% 100 µm 2 $$<br />

XAS No No Yes Yes Yes* Yes** He-U No ppb 2 µm 5 $$$$<br />

PIXIE No No No No Yes Yes** B-U No 10 ppm 4 µm 4 $$$$<br />

* Technique requires each element be tuned and standardized, requiring unreasonable time limits.<br />

** Techniques designed and tested only on simple systems. Multiple species require lengthy analytical times and data reduction.<br />

*** Limited when combined with ICP/MS/LA.<br />

# Identifies crystalline compounds and stoichiometric compositions only.<br />

? Technique has limitations based on particle counting statistics.<br />

+ Valance determined by charge balance <strong>of</strong> complete analyses.<br />

Element<br />

Specificity<br />

Isotopic<br />

Character<br />

Element<br />

Sensitivity<br />

Resolution<br />

Availability<br />

Cost


techniques can be useful in a study <strong>of</strong> metal uptake in plants, where transfer takes place<br />

predominately via a solution phase. However, one must keep in mind that they are not<br />

“selective” in metal species, give no particle size in<strong>for</strong>mation and, above all, these leachable<br />

fractions have never been correlated to bioavailability.<br />

Solution Speciation Using Computer-Based Models. Computer-based models are either<br />

based upon equilibrium constants or upon Gibb’s free energy values in determining metal<br />

speciation from solution chemistry conditions (concentration, pH, Eh, organic complexes,<br />

adsorption/desorption sites, and temperature). Both approaches are subject to mass balance and<br />

equilibrium conditions. These models have undergone a great deal <strong>of</strong> development in recent<br />

years, as reliable thermodynamic data has become available and can provide some predictive<br />

estimates <strong>of</strong> metal behavior. A good review <strong>of</strong> these models and their applications is provided<br />

by Lumsdon and Evans (1995).<br />

Speciation can be controlled by simple reactions; however, in many cases, particularly in<br />

contaminated media, their state <strong>of</strong> equilibrium and reversibility are unknown. In addition, these<br />

models suffer from other limitations such as a lack <strong>of</strong> reliable thermodynamic data on relevant<br />

species, inadequacies in models to correct <strong>for</strong> high ionic strength, reaction kinetics are poorly<br />

known, and complex reactions with co-precipitation/adsorption are not modeled.<br />

The first limitation is perhaps the most significant <strong>for</strong> contaminated media. For example,<br />

none <strong>of</strong> the models would predict the common, anthropogenic, Pb phases, i.e., paint, solder,<br />

and slag.<br />

AX7.1.1.4 Biotic Ligand Model<br />

The biotic ligand model (BLM) is an equilibrium-based conceptual model that has been<br />

incorporated into regulatory agencies guidelines (including the <strong>EPA</strong>) to predict effects <strong>of</strong> metals<br />

primarily on aquatic biota and to aid in the understanding <strong>of</strong> their interactions with biological<br />

surfaces (see Annex Section AX7.2.1.3).<br />

Because <strong>of</strong> assumed similarities in mechanisms <strong>of</strong> toxicity between aquatic and terrestrial<br />

organisms, it is likely that the BLM approach as developed <strong>for</strong> the aquatic compartment may also<br />

be applicable to the terrestrial environment. Recent research has been directed toward extending<br />

the BLM to predict metal toxicity in soils (Steenbergen et al., 2005). Steenbergen et al. (2005)<br />

pointed out that, until recently, the BLM concept has not been applied to predict toxicity to soil<br />

AX7-18


organisms. The authors believe there may be two reasons <strong>for</strong> this. First, metal uptake routes in<br />

soils are generally more complex than those in water, because exposure via pore water and<br />

exposure via ingestion <strong>of</strong> soil particles may, in principle, both be important. Second, it remains<br />

very difficult to univariately control the composition <strong>of</strong> the soil pore water and the metal<br />

concentrations in the pore water, due to re-equilibration <strong>of</strong> the system following modification <strong>of</strong><br />

any <strong>of</strong> the soil properties (including addition <strong>of</strong> metal salts).<br />

Steenbergen et al. (2005) assessed acute copper toxicity to the earthworm Aporrectodea<br />

caliginosa using the BLM. To overcome the a<strong>for</strong>ementioned problems inherent in soil toxicity<br />

tests they developed an artificial flow-through exposure system consisting <strong>of</strong> an inert quartz sand<br />

matrix and a nutrient solution, <strong>of</strong> which the composition was univariately modified. Thus, the<br />

obstacles in employing the BLM to terrestrial ecosystems seem to be surmountable, and future<br />

research may provide useful in<strong>for</strong>mation on Pb bioavailability and toxicity to terrestrial<br />

organisms.<br />

AX7.1.1.5 Soil Amendments<br />

The removal <strong>of</strong> contaminated soil to mitigate exposure <strong>of</strong> terrestrial ecosystem<br />

components to Pb can <strong>of</strong>ten present both economic and logistic problems. Because <strong>of</strong> this,<br />

recent studies have focused on in situ methodologies to lower soil-Pb RBA (Brown et al.,<br />

2003a,b). To date, the most common methods studied include the addition <strong>of</strong> soil amendments<br />

in an ef<strong>for</strong>t either to lower the solubility <strong>of</strong> the Pb <strong>for</strong>m or to provide sorbtion sites <strong>for</strong> fixation <strong>of</strong><br />

pore-water Pb. These amendments typically fall within the categories <strong>of</strong> phosphate, biosolid,<br />

and Al/Fe/Mn-oxide amendments.<br />

Phosphate Amendments<br />

Phosphate amendments have been studied extensively and, in some cases, <strong>of</strong>fer the most<br />

promising results (Brown et al., 1999; Ryan et al., 2001; Cotter-Howells and Caporn, 1996;<br />

Hettiarachchi et al., 2001, 2003; Rabinowitz, 1993; Yang et al., 2001; Ma et al., 1995). Research<br />

in this area stems from early work by Nriagu (1973) and Cotter-Howells and Caporn (1996), who<br />

pointed out the very low solubilities <strong>for</strong> many Pb-phosphates (Ksp !27 to !66), particularly<br />

chloropyromorphite [Pb5(PO4)3Cl]. The quest to trans<strong>for</strong>m soluble Pb mineralogical <strong>for</strong>ms into<br />

chloropyromorthite continues to be the primary focus <strong>of</strong> most studies. Sources <strong>of</strong> phosphorous<br />

AX7-19


have included phosphoric acid (H3PO4), triple-super phosphate (TSP), phosphate rock, and/or<br />

hydroxyapatite (HA). Various studies have combined one or more <strong>of</strong> these phosphorous sources<br />

with or without lime, iron, and/or manganese in an attempt to enhance amendment qualities.<br />

Most amendments are <strong>for</strong>mulated to contain between 0.5 and 1.0% phosphorous by weight.<br />

They are then either applied wet or dry and then mixed or left unmixed with the contaminated<br />

soil. Success <strong>of</strong> phosphate amendments has been variable, and the degree <strong>of</strong> success appears to<br />

depend on available phosphorous and the dissolution rate <strong>of</strong> the original Pb species.<br />

A number <strong>of</strong> potentially significant problems associated with phosphate amendments have<br />

been recognized, including both phyto- and earthworm toxicity (Ownby et al., 2005; Cao et al.,<br />

2002; and Rusek and Marshall, 2000). Both <strong>of</strong> these toxicities are primarily associated with very<br />

high applications <strong>of</strong> phosphorous and/or decreased soil pH. Indications <strong>of</strong> phytotoxicity are<br />

<strong>of</strong>ten balanced by studies such as Zhu et al. (2004) that illustrate a 50 to 70% reduction in shoot-<br />

root uptake <strong>of</strong> Pb in phosphate-amended soils. Additionally, the added phosphate poses the<br />

potential risk <strong>of</strong> eutrophication <strong>of</strong> nearby waterways from soil run<strong>of</strong>f. Finally, Pb-contaminated<br />

soils from the extractive metals industry or agricultural sites <strong>of</strong>ten have elevated concentrations<br />

<strong>of</strong> arsenic. It has been shown (Impellitteri, 2005; Smith et al., 2002; Chaney and Ryan, 1994;<br />

and Ruby et al., 1994) that the addition <strong>of</strong> phosphate to such soils would enhance arsenic<br />

mobility (potentially moving arsenic down into the groundwater) through competitive anion<br />

exchange. Some data (Lenoble et al., 2005) indicate that if one could amend arsenic and Pb<br />

contaminated soils with iron(<strong>II</strong>I) phosphate this problem can be mitigated, however the increased<br />

concentrations <strong>of</strong> both phosphate and iron still exclude the application when drinking water is an<br />

issue.<br />

Biosolid Amendments<br />

Historically, biosolids have been used in the restoration <strong>of</strong> coal mines (Haering et al.,<br />

2000; Sopper, 1993). More recently, workers have demonstrated the feasibility <strong>of</strong> their use in<br />

the restoration <strong>of</strong> mine tailings (Brown et al., 2003a), and urban soils (Brown et al., 2003b;<br />

Farfel et al., 2005). Mine tailings are inherently difficult to remediate in that they pose numerous<br />

obstacles to plant growth. They are most <strong>of</strong>ten (1) acidic; (2) high in metal content, thus prone to<br />

phytotoxicity; (3) very low in organic content; and (4) deficient in macro- and micronutrients.<br />

AX7-20


Stabilization (i.e., the establishment <strong>of</strong> a vegetative cover) <strong>of</strong> these environments is essential to<br />

the control <strong>of</strong> metal exposure or migration from soil/dust and groundwater pathways.<br />

At Bunker Hill, ID, Brown et al. (2003b) demonstrated that a mixture <strong>of</strong> high nitrogen<br />

biosolids and wood pulp or ash, when surface applied at a rate <strong>of</strong> approximately 50 and<br />

220 tons/ha, respectively, increased soil pH from 6.8 to approximately 8.0, increased plant<br />

biomass from 0.01 mg/ha to more than 3.4 tons/ha, and resulted in a healthy plant cover within<br />

2 years. Metal mobility was more difficult to evaluate. Plant concentrations <strong>of</strong> Zn and Cd were<br />

generally normal <strong>for</strong> the first 2 years <strong>of</strong> the study; however, Pb concentrations in vegetation<br />

dramatically increased two to three times in the first year. Additionally, macronutrients (Ca, K,<br />

and Mg) decreased in plant tissue.<br />

Urban soils, whether contaminated from smelting, paint, auto emissions, or industrial<br />

activity, are <strong>of</strong>ten contaminated with Pb (Agency <strong>for</strong> Toxic Substances and Disease Registry<br />

[ATSDR], 1988) and can be a significant pathway to elevated child blood Pb levels (Angle et al.,<br />

1974). Typically, contaminated residential soils are replaced under Superfund rules. However,<br />

urban soils are less likely to be remediated unless a particular facility is identified as the<br />

contaminate source. Application <strong>of</strong> biosolids to such soils may be a cost-effective means <strong>for</strong><br />

individuals or communities to lower Pb RBAs.<br />

A field study by Farfel et al. (2005) using the commercial biosolid ORGO found that,<br />

over a 1-year period, Pb in the dripline soils <strong>of</strong> one residence had reduced RBAs by ~60%.<br />

However, soils throughout the remainder <strong>of</strong> the yard showed either no reduction in RBA or a<br />

slight increase. A more complex study was conducted by Brown et al. (2003a) on an urban<br />

dripline soil in the lab. The study used an assortment <strong>of</strong> locally derived biosolids (raw, ashed,<br />

high-Fe compost, and compost) with and without lime. All amendments were incubated with<br />

approximately 10% biosolids <strong>for</strong> a little more than 30 days. In vitro and in vivo data both<br />

indicated a 3 to 54% reduction in Pb RBA, with the high-Fe compost providing the greatest<br />

reduction.<br />

As with phosphate amendments, problems with biosolid application have also been<br />

documented. Studies have shown that metal transport is significantly accelerated in soils<br />

amended with biosolids (Al-Wabel et al., 2002; McBride et al., 1997, 1999; Lamy et al., 1993;<br />

Richards et al., 1998, 2000). Some <strong>of</strong> these studies indicate that metal concentrations in soil<br />

solutions up to 80 cm below the amended surface increased by 3- to 20-fold in concentration up<br />

AX7-21


to 15 years after biosolid application. The increase in metal transport is likely the result <strong>of</strong><br />

elevated dissolved organic carbon (DOC) in the amended soil. Anodic stripping voltammetry<br />

has indicated that very low percentages (2 to 18%) <strong>of</strong> the soluble metals are present as ionic or<br />

inorganic complexes (McBride, 1999; Al-Wabel et al., 2002).<br />

AX7.1.2 Distribution <strong>of</strong> Atmospherically Delivered <strong>Lead</strong> in<br />

Terrestrial Ecosystems<br />

The 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a) contains only a<br />

few minor sections that detail the speciation, distribution, and behavior <strong>of</strong> atmospherically<br />

delivered Pb in terrestrial ecosystems. The document concluded that the majority <strong>of</strong> Pb in the<br />

atmosphere at that time was from gasoline consumption: <strong>of</strong> the 34,881 tons <strong>of</strong> Pb emitted to the<br />

atmosphere in 1984, 89% was from gasoline use and minor amounts were from waste oil<br />

combustion, iron and steel production, and smelting. <strong>Lead</strong> in the atmosphere today, however, is<br />

not primarily from leaded-gasoline consumption, but results largely from iron and steel<br />

foundaries, boilers and process heaters, the combustion <strong>of</strong> fossil fuels in automobiles, trucks,<br />

airplanes, and ships, and other industrial processes (Table 2-8, Polissar et al., 2001; Newhook<br />

et al., 2003). The emission source can determine the species <strong>of</strong> Pb that are delivered to terrestrial<br />

ecosystems. For example, Pb species emitted from automobile exhaust is dominated by<br />

particulate Pb halides and double salts with ammonium halides (e.g., PbBrCl, PbBrCl2NH4Cl),<br />

while Pb emitted from smelters is dominated by Pb-sulfur species (Habibi, 1973). The halides<br />

from automobile exhaust break down rapidly in the atmosphere, possibly via reactions with<br />

atmospheric acids (Biggins and Harrison, 1979). <strong>Lead</strong> phases in the atmosphere, and<br />

presumably the compounds delivered to the surface <strong>of</strong> the earth (i.e., to vegetation and soils),<br />

are suspected to be in the <strong>for</strong>m <strong>of</strong> PbSO4, PbS, and PbO (Olson and Skogerboe, 1975; Clevenger<br />

et al., 1991; Utsunomiya et al., 2004).<br />

There are conflicting reports <strong>of</strong> how atmospherically derived Pb specifically behaves in<br />

surface soils. This disagreement may represent the natural variability <strong>of</strong> the biogeochemical<br />

behavior <strong>of</strong> Pb in different terrestrial systems, the different Pb sources, or it may be a function <strong>of</strong><br />

the different analytical methods employed. The importance <strong>of</strong> humic and fulvic acids (Zimdahl<br />

and Skogerboe, 1977; Gamble et al., 1983) and hydrous Mn- and Fe-oxides (Miller and McFee,<br />

1983) <strong>for</strong> scavenging Pb in soils are discussed in some detail in the 1986 <strong>Lead</strong> AQCD. Nriagu<br />

AX7-22


(1974) used thermodynamics to argue that Pb-orthophosphates (e.g., pyromorphite) represented<br />

the most stable Pb phase in many soils and sediments. He further suggested that, because <strong>of</strong> the<br />

extremely low solubility <strong>of</strong> Pb-phosphate minerals, Pb deposition could potentially reduce<br />

phosphorous availability. Olson and Skogerboe (1975) reported that solid-phase PbSO4<br />

dominated gasoline-derived Pb speciation in surface soils from Colorado, Missouri, and Chicago,<br />

while Santillan-Medrano and Jurinak (1975) suggested that Pb(OH)2, Pb(PO4)2, and PbCO3<br />

could regulate Pb speciation in soils. However, insoluble organic material can bind strongly to<br />

Pb and prevent many inorganic phases from ever <strong>for</strong>ming in soils (Zimdahl and Skogerboe,<br />

1977).<br />

The vertical distribution and mobility <strong>of</strong> atmospheric Pb in soils was poorly documented<br />

prior to 1986. Chapter 6 <strong>of</strong> the 1986 AQCD cited a few references suggesting that atmospheric<br />

Pb is retained in the upper 5 cm <strong>of</strong> soil (Reaves and Berrow, 1984). Techniques using radiogenic<br />

Pb isotopes had been developed to discern between gasoline-derived Pb and natural, geogenic<br />

(native) Pb, but these techniques were mostly applied to sediments (Shirahata et al., 1980) prior<br />

to the 1986 <strong>Lead</strong> AQCD. Without using these techniques, accurate determinations <strong>of</strong> the depth-<br />

distribution and potential migration velocities <strong>for</strong> atmospherically delivered Pb in soils were<br />

largely unavailable.<br />

Several technological advances, combined with the expansion <strong>of</strong> existing technologies<br />

after 1986 resulted in the publication <strong>of</strong> a large body <strong>of</strong> literature detailing the speciation,<br />

distribution, and geochemical behavior <strong>of</strong> gasoline-derived Pb in the terrestrial environment.<br />

Most notably, the development <strong>of</strong> selective chemical extraction (SCE) procedures as a rapid and<br />

inexpensive means <strong>for</strong> partitioning Pb into different soil and sediment phases (e.g., Pb-oxides,<br />

Pb-humate, etc.) has been exploited by a number <strong>of</strong> researchers (Tessier et al., 1979; Johnson<br />

and Petras, 1998; Ho and Evans, 2000; Scheckel et al., 2003). Also, since 1986, several workers<br />

have exploited synchrotron-based XAS in order to probe the electron coordination environment<br />

<strong>of</strong> Pb in soils, organic matter, organisms, and sediments (Manceau et al., 1996; Xia et al., 1997;<br />

Trivedi et al., 2003). X-ray absorption studies can be used <strong>for</strong> the in-situ determination <strong>of</strong> the<br />

valence state <strong>of</strong> Pb and can be used to quantify Pb speciation in a variety <strong>of</strong> untreated samples.<br />

Biosensors, which are a relatively new technology coupling biological material, such as an<br />

enzyme, with a transducer, <strong>of</strong>fer a new, simple, and inexpensive means <strong>for</strong> quantifying available<br />

Pb in ecosystems (Verma and Singh, 2005). Advances in voltammetric, diffusive gradients in<br />

AX7-23


thin films (DGT), and ICP techniques have also increased the abilities <strong>of</strong> researchers to quantify<br />

Pb phases in solutions (Berbel et al., 2001; Scally et al., 2003). In addition to the development <strong>of</strong><br />

techniques <strong>for</strong> describing and quantifying Pb species in the soils and solutions, researchers have<br />

used radiogenic Pb isotopes ( 206 Pb, 207 Pb, 208 Pb) to quantify the distribution, speciation, and<br />

transport <strong>of</strong> anthropogenic Pb in soil pr<strong>of</strong>iles and in vegetation (Bindler et al., 1999; Erel et al.,<br />

2001; Kaste et al., 2003; Klaminder et al., 2005).<br />

Over the past several decades, workers have also developed time-series data <strong>for</strong> Pb in<br />

precipitation, vegetation, organic horizons, mineral soils, and surface waters. Since<br />

atmospherically delivered Pb <strong>of</strong>ten comprises a significant fraction <strong>of</strong> the “labile” Pb (i.e., Pb not<br />

associated with primary minerals), these data have been useful <strong>for</strong> developing transport and<br />

residence time models <strong>of</strong> Pb in different terrestrial reservoirs (Friedland et al., 1992; Miller and<br />

Friedland, 1994; Johnson et al., 1995a; Wang and Benoit, 1997). Overall, a significant amount<br />

<strong>of</strong> research has been published on the distribution, speciation, and behavior <strong>of</strong> anthropogenic Pb<br />

in the terrestrial environment since 1986. However, certain specific details on the behavior <strong>of</strong> Pb<br />

in the terrestrial environment and its potential effects on soil microorganisms remain elusive.<br />

AX7.1.2.1 Speciation <strong>of</strong> Atmospherically-delivered <strong>Lead</strong> in Terrestrial Ecosystems<br />

<strong>Lead</strong> in the Solid Phases<br />

<strong>Lead</strong> can enter terrestrial ecosystems through natural rock weathering and by a variety <strong>of</strong><br />

anthropogenic pathways. These different source terms control the species <strong>of</strong> Pb that is<br />

introduced into the terrestrial environment. While Pb is highly concentrated (percent level) in<br />

certain hydrothermal sulfide deposits (e.g., PbS) that are disseminated throughout parts <strong>of</strong> the<br />

upper crust, these occurrences are relatively rare. There<strong>for</strong>e, the occurrence <strong>of</strong> Pb as a minor<br />

constituent <strong>of</strong> rocks (ppm level), particularly granites, rhyolites, and argillaceous sedimentary<br />

rocks is the more pertinent source term <strong>for</strong> the vast majority <strong>of</strong> terrestrial ecosystems. During<br />

the hydrolysis and oxidation <strong>of</strong> Pb-containing minerals, divalent Pb is released to the soil<br />

solution where it is rapidly fixed by organic matter and secondary mineral phases (Kabata-<br />

Pendias and Pendias, 1992). The geochemical <strong>for</strong>m <strong>of</strong> natural Pb in terrestrial ecosystems will<br />

be strongly controlled by soil type (Emmanuel and Erel, 2002). In contrast, anthropogenically<br />

introduced Pb has a variety <strong>of</strong> different geochemical <strong>for</strong>ms, depending on the specific source.<br />

While Pb in soils from battery reclamation areas can be in the <strong>for</strong>m <strong>of</strong> PbSO4 or PbSiO3, Pb in<br />

AX7-24


soils from shooting ranges and paint spills is commonly found as PbO and a variety <strong>of</strong> Pb<br />

carbonates (Vantelon et al., 2005; Laperche et al., 1996; Manceau et al., 1996). Atmospherically<br />

delivered Pb resulting from fossil fuel combustion is typically introduced into terrestrial<br />

ecosystems as Pb-sulfur compounds and Pb oxides (Olson and Skogerboe, 1975; Clevenger<br />

et al., 1991; Utsunomiya et al., 2004). After deposition, Pb species are likely trans<strong>for</strong>med.<br />

Although the specific factors that control the speciation <strong>of</strong> anthropogenic Pb speciation in soils<br />

are not well understood, there are many studies that have partitioned Pb into its different<br />

geochemical phases. A thorough understanding <strong>of</strong> Pb speciation is critical in order to predict<br />

potential mobility and bioavailability (see Section AX7.1.1).<br />

Selective chemical extractions have been employed extensively over the past 20 years <strong>for</strong><br />

quantifying amounts <strong>of</strong> a particular metal phase (e.g., PbS, Pb-humate, Pb-Fe/Mn-oxide) present<br />

in soil or sediment rather than total metal concentration. Sometimes selective chemical<br />

extractions are applied sequentially to a particular sample. For example, the exchangeable metal<br />

fraction is removed from the soil using a weak acid or salt solution (e.g., BaCl2), followed<br />

immediately by an extraction targeting organic matter (e.g., H2O2 or NaOCl), further followed by<br />

an extraction targeting secondary iron oxides (e.g., NH2OH·HCl), and finally, a strong reagent<br />

cocktail (e.g., HNO3-HCl-HF) targets primary minerals. Tessier et al. (1979) developed this<br />

technique. More recently, this technique has been modified and developed specifically <strong>for</strong><br />

different metals and different types <strong>of</strong> materials (Keon et al., 2001). Alternatively, batch-style<br />

selective chemical extractions have been used on soils and sediments to avoid the problems<br />

associated with nonselective reagents (Johnson and Petras, 1998). Selective extractions can be a<br />

relatively rapid, simple, and inexpensive means <strong>for</strong> determining metal phases in soils and<br />

sediments, and the generated data can be linked to potential mobility and bioavailability <strong>of</strong> the<br />

metal (Tessier and Campbell, 1987). However, some problems persist with the selective<br />

extraction technique. First, extractions are rarely specific to a single phase. For example, while<br />

H2O2 is <strong>of</strong>ten used to remove metals bound to organic matter in soils, others have demonstrated<br />

that this reagent destroys clay minerals and sulfides (Ryan et al., 2002). Peroxide solutions may<br />

also be inefficient in removing metals bound to humic acids, and in fact could potentially result<br />

in the precipitation <strong>of</strong> metal-humate substances. In addition to the nonselectivity <strong>of</strong> reagents,<br />

significant metal redistribution has been documented to occur during sequential chemical<br />

extractions (Ho and Evans, 2000; Sulkowski and Hirner, 2006), and many reagents may not<br />

AX7-25


completely extract targeted phases. While chemical extractions provide some useful in<strong>for</strong>mation<br />

on metal phases in soil or sediment, the results should be treated as “operationally defined,” e.g.,<br />

“H2O2-liberated Pb” rather than “organic Pb.”<br />

<strong>Lead</strong> <strong>for</strong>ms strong coordination complexes with oxygen on mineral surfaces and organic<br />

matter functional groups (Abd-Elfattah and Wada, 1981), because <strong>of</strong> its high electronegativity<br />

and hydrolysis constant. There<strong>for</strong>e, Pb is generally not readily exchangeable, i.e., the amount <strong>of</strong><br />

Pb removed from soils by dilute acid or salts is usually less that 10% (Karamanos et al., 1976;<br />

Sposito et al., 1982; Miller and McFee, 1983; Johnson and Petras, 1998; Bacon and Hewitt,<br />

2005). <strong>Lead</strong> is typically adsorbed to organic and inorganic soil particles strongly via inner-<br />

sphere adsorption (Xia et al., 1997; Bargar et al., 1997a,b, 1998). Kaste et al. (2005) found that a<br />

single extract <strong>of</strong> 0.02 M HCl removed 15% or less Pb in organic horizons from a montane <strong>for</strong>est<br />

in New Hampshire. The fact that relatively concentrated acids, reducing agents, oxidizing<br />

agents, or chelating agents are required to liberate the majority <strong>of</strong> Pb from soils is used as one<br />

line <strong>of</strong> evidence that Pb migration and uptake by plants in soils is expected to be low.<br />

<strong>Lead</strong> that is “organically bound” in soils is typically quantified by extractions that<br />

dissolve/disperse or destroy organic matter. The <strong>for</strong>mer approach <strong>of</strong>ten employs an alkaline<br />

solution (NaOH), which deprotonates organic matter functional groups, or a phosphate solution,<br />

which chelates structural cations. Extractions used to destroy organic matter <strong>of</strong>ten rely on H2O2<br />

or NaOCl. Both organic and mineral horizons typically have significant Pb in this soil phase.<br />

Miller and McFee (1983) used Na4P2O7 to extract organically bound Pb from the upper 2.5 cm <strong>of</strong><br />

soils sampled from northwestern Indiana. They found that organically bound Pb accounted <strong>for</strong><br />

between 25 and 50% <strong>of</strong> the total Pb present in the sampled topsoils. Jersak et al. (1997), Johnson<br />

and Petras (1998), and Kaste et al. (2005) selectively extracted Pb from spodosols from the<br />

northeastern United States. Using acidified H2O2, Jersak et al. (1997) found that very little<br />

(


They found that repeated extractions with Na4P2O7 removed between 60 and 100% <strong>of</strong> the Pb<br />

from their samples. Caution should be used when interpreting the results <strong>of</strong> pyrophosphate<br />

extractions. Although they are <strong>of</strong>ten used to quantify organically bound metals, this reagent can<br />

both disperse and dissolve Fe phases (Jeanroy and Guillet, 1981; Shuman, 1982). Acidified<br />

H2O2 has also been reported to destroy and release elements associated with secondary soil<br />

minerals (Papp et al., 1991; Ryan et al., 2002).<br />

Aside from organic <strong>for</strong>ms, Pb is <strong>of</strong>ten found to be associated with secondary oxide<br />

minerals in soils. Pb can be partitioned with secondary oxides by a variety <strong>of</strong> mechanisms,<br />

including (1) simple ion exchange, (2) inner-sphere or outer-sphere adsorption, and (3) co-<br />

precipitation and/or occlusion (Bargar et al., 1997a,b, 1998, 1999). As discussed above, very<br />

little Pb is removed from soil via dilute acid or salt solutions, so adsorption and co-precipitation<br />

are likely the dominant Pb interactions with secondary mineral phases. Reagents used to<br />

quantify this phase are <strong>of</strong>ten solutions <strong>of</strong> EDTA, oxalate, or hydroxylamine hydrochloride (HH).<br />

Miller and McFee (1983) used an EDTA solution followed by an HH solution to quantify Pb<br />

occluded by Fe and Mn minerals, respectively, in their surface-soil samples from Indiana. They<br />

reported that approximately 30% <strong>of</strong> the total soil Pb was occluded in Fe minerals, and 5 to 15%<br />

was occluded in Mn phases. In soils from the northeastern United States, Jersak et al. (1997)<br />

used various strengths <strong>of</strong> HH solutions and concluded that negligible Pb was associated with<br />

Mn-oxides and that 1 to 30% <strong>of</strong> the Pb was associated with Fe phases in the mineral soils in their<br />

study. Johnson and Petras (1998) reported that no Pb was removed from the Oa horizon at the<br />

Hubbard Brook Experimental Forest (HBEF) by oxalate, but that 5 to 15% <strong>of</strong> the total Pb in<br />

mineral soils was removed by this extraction, presumably because it was bound to amorphous<br />

oxide minerals. Kaste et al. (2005), however, reported that HH removed 30 to 40% <strong>of</strong> the Pb<br />

from organic horizons in their study. They concluded that Fe phases were important in<br />

scavenging Pb, even in soil horizons dominated by organic matter.<br />

Synchrotron radiation (X-rays) allows researchers to probe the electron configuration <strong>of</strong><br />

metals in untreated soil and sediment samples. This type <strong>of</strong> analysis has been extremely valuable<br />

<strong>for</strong> directly determining the coordination environment <strong>of</strong> Pb in a variety <strong>of</strong> soils and sediments.<br />

Since different elements have different electron binding energies (Eb), X-rays can be focused in<br />

an energy window specific to a metal <strong>of</strong> interest. In experiments involving XAS, X-ray energy is<br />

increased until a rapid increase in the amount <strong>of</strong> absorption occurs; this absorption edge<br />

AX7-27


epresents Eb. The precise energy required to dislodge a core electron from a metal (i.e., Eb) will<br />

be a function <strong>of</strong> the oxidation state and covalency <strong>of</strong> the metal. X-ray absorption studies that<br />

focus on the location <strong>of</strong> the absorption edge are referred to as XANES (X-ray absorption near<br />

edge structure). In the energy region immediately after the absorption edge, X-ray absorption<br />

increases and decreases with a periodicity that represents the wave functions <strong>of</strong> the ejected<br />

electrons and the constructive and destructive interference with the wave functions <strong>of</strong> the nearby<br />

atoms. X-ray absorption studies used to investigate the periodicity <strong>of</strong> the absorption after Eb are<br />

referred to as EXAFS (extended X-ray absorption fine structure). Since the electron<br />

configuration <strong>of</strong> a Pb atom will be directly governed by its speciation (e.g., Pb bound to organics,<br />

Pb adsorbed to oxide surfaces, PbS, etc.) X-ray absorption studies provide a powerful in-situ<br />

technique <strong>for</strong> determining speciation without some <strong>of</strong> the problems associated with chemical<br />

extractions (Bargar et al., 1997a,b, 1998).<br />

Manceau et al. (1996) used EXAFS to study soil contaminated by gasoline-derived Pb in<br />

France and found that the Pb was divalent and complexed to salicylate and catechol-type<br />

functional groups <strong>of</strong> humic substances. He concluded that the alkyl-tetravalent Pb compounds<br />

that were added to gasoline were relatively unstable and will not dominate the speciation <strong>of</strong> Pb<br />

fallout from the combustion <strong>of</strong> leaded gasoline. The binding mechanism <strong>of</strong> Pb to organics is<br />

primarily inner-sphere adsorption (Xia et al., 1997). DeVolder et al. (2003) used EXAFS to<br />

demonstrate that Pb phases were shifting to the relatively insoluble PbS when contaminated<br />

wetland soils were treated with sulfate. Strawn and Sparks (2000) gave evidence that added Pb<br />

was adsorbed directly onto organic matter in an untreated silt loam, but in the absence <strong>of</strong> organic<br />

matter (treated with sodium hypochlorite) the added Pb appeared to adsorb instead to some <strong>for</strong>m<br />

<strong>of</strong> SiO2. More recent XAS studies have demonstrated the importance <strong>of</strong> biomineralization <strong>of</strong> Pb<br />

in soils by bacteria and nematodes (Xia et al., 1997; Templeton et al., 2003a,b; Jackson et al.,<br />

2005). Templeton et al. (2003a,b) demonstrated that biogenic precipitation <strong>of</strong> pyromorphite was<br />

the dominant source <strong>of</strong> Pb uptake by Burkholderia cepacia bi<strong>of</strong>ilms below pH 4.5. Above pH<br />

4.5, adsorption complexes began to <strong>for</strong>m in addition to Pb mineral precipitation.<br />

In addition to XAS studies <strong>of</strong> Pb in environmental samples, numerous experimental-based<br />

XAS studies have documented in detail the coordination environment <strong>of</strong> Pb adsorbed to Feoxides,<br />

Mn-oxides, Al-oxides, and clay minerals (Manceau et al., 1996, 2000a,b, 2002; Bargar<br />

et al., 1997a,b, 1998, 1999; Strawn and Sparks, 1999; Trivedi et al., 2003; Chen et al., 2006).<br />

AX7-28


Bargar et al. (1997a) showed that Pb can adsorb to FeO6 octahedra on three different types <strong>of</strong><br />

sites: on corners, edges, or faces. Ostergren et al. (2000a,b) showed that the presence <strong>of</strong><br />

dissolved carbonate and sulfate increased Pb adsorbtion on goethite. The relative fraction <strong>of</strong><br />

corner-sharing complexes can be greatly increased by the presence <strong>of</strong> these ligands, as bridging<br />

complexes between the metal and the corners are <strong>for</strong>med (Ostergren et al., 2000a,b).<br />

Furthermore, Elzinga and Sparks showed that the mechanism <strong>of</strong> Pb sorption to SiO2 surfaces is<br />

pH-dependent. In acid environments (pH < 4) Pb adsorbs largely as an inner-sphere mononulear<br />

complex, but as pH increases, Pb sorption increasingly occurs via the <strong>for</strong>mation <strong>of</strong> surface-<br />

attached covalent polynuclear Pb species.<br />

Recently, Jackson et al. (2005) used micr<strong>of</strong>ocused synchrotron-based X-ray fluorescence<br />

(ΦSXRF) to detail the distribution <strong>of</strong> Pb and Cu in the nematode Caenorhabditis elegans. They<br />

found that, while Cu was evenly distributed throughout the bodies <strong>of</strong> exposed C. elegans, Pb was<br />

concentrated in the anterior pharynx region. Micr<strong>of</strong>ocused X-ray diffraction indicated that the<br />

highly concentrated Pb region in the pharynx was actually comprised <strong>of</strong> the crystalline Pb<br />

mineral, pyromorphite. The authors concluded that C. elegans precipitated pyromorphite in the<br />

pharynx as a defense mechanism to prevent spreading the toxic metal to the rest <strong>of</strong> the<br />

organism’s body. They further suggested that, because <strong>of</strong> the high turnover rate <strong>of</strong> nematodes,<br />

biomineralization could play an important role in the speciation <strong>of</strong> Pb in certain soils.<br />

<strong>Lead</strong> Solid-solution Partitioning<br />

The concentration <strong>of</strong> Pb species dissolved in soil solution is probably controlled by some<br />

combination <strong>of</strong> (a) Pb-mineral solubility equilibria, (b) adsorption reactions <strong>of</strong> dissolved Pb<br />

phases on inorganic surfaces (e.g., crystalline or amorphous oxides <strong>of</strong> Al, Fe, Si, Mn, etc.; clay<br />

minerals), and (c) adsorption reactions <strong>of</strong> dissolved Pb phases on soil organic matter. Dissolved<br />

Pb phases in soil solution can be some combination <strong>of</strong> Pb 2+ and its hydrolysis species, Pb bound<br />

to dissolved organic matter, and Pb complexes with inorganic ligands such as Cl ! and SO4 2! .<br />

Alkaline soils typically have solutions supersaturated with respect to PbCO3, Pb3(CO3)2(OH)2,<br />

Pb(OH)2, Pb3(PO4)2, Pb5(PO4)3(OH), and Pb4O(PO4)2 (Badawy et al., 2002). Pb-phosphate<br />

minerals in particular are very insoluble, and calculations based on thermodynamic data predict<br />

that these phases will control dissolved Pb in soil solution under a variety <strong>of</strong> conditions (Nriagu,<br />

AX7-29


1974; Ruby et al., 1994). However, certain chelating agents, such as dissolved organic matter,<br />

can prevent the precipitation <strong>of</strong> Pb minerals (Lang and Kaupenjohann, 2003).<br />

Using a combination <strong>of</strong> desorption experiments and XAS, EXAFS, and XANES, Rouff<br />

et al. (2006) found that aging <strong>of</strong> Pb-calcite suspensions resulted in changes in the solid-phase<br />

distribution <strong>of</strong> Pb. Increased sorption time can reduce trace metal desorption by enhancing the<br />

stability <strong>of</strong> surface complexes (Rouff et al., 2005) or by mechanisms involving microporous<br />

diffusion (Backes et al., 1995), recrystallization-induced incorporation into the solid phase<br />

(Ainsworth et al., 1994), and <strong>for</strong>mation and stabilization <strong>of</strong> surface precipitates (Ford et al.,<br />

1999). For adsorption <strong>of</strong> Pb to hydrous Fe oxides, goethite, and Pb-contaminated soils, aged<br />

samples show Pb to be reversibly bound, suggesting Pb adsorption primarily to the substrates’<br />

surfaces (Rouff et al., 2006). However, <strong>for</strong> Pb adsorption to calcite aging played a significant<br />

role due to detection <strong>of</strong> multiple sorption mechanisms, even <strong>for</strong> short sorption times (Rouff et al.,<br />

2006). pH also played a role in Pb sorption. Over long sorption periods (60 to 270 days), slow<br />

continuous uptake <strong>of</strong> Pb occurred at pH 7.3 and 8.2. At pH 9.4, no further uptake occurred with<br />

aging and very little desorption occurred. These results show the importance <strong>of</strong> contact time and<br />

pH on Pb solid-phase partitioning, particularly in geochemical systems in which calcite may be<br />

the predominant mineralogical constituent.<br />

Soil solution dissolved organic matter content and pH typically have very strong positive<br />

and negative correlations, respectively, with the concentration <strong>of</strong> dissolved Pb species (Sauvé<br />

et al., 1998, 2000a, 2003; Weng et al., 2002; Badawy et al., 2002; Tipping et al., 2003). In the<br />

case <strong>of</strong> adsorption phenomena, the partitioning <strong>of</strong> Pb 2+ to the solid phase is also controlled by<br />

total metal loading, i.e., high Pb loadings will result in a lower fraction being partitioned to the<br />

solid phase. Sauvé et al. (1997, 1998) demonstrated that only a fraction <strong>of</strong> the total Pb in<br />

solution was actually Pb 2+ in soils treated with leaf compost. The fraction <strong>of</strong> Pb 2+ to total<br />

dissolved Pb ranged from


and partitioning experiments. This technique has been particularly useful <strong>for</strong> quantifying the Kd,<br />

or partitioning ratio <strong>of</strong> Pb in the solid-to-liquid phase (Kd = [total solid-phase metal in mg kg Γ1 ] /<br />

[dissolved metal in mg L !1 ]). While the exact Kd value is a function <strong>of</strong> pH, organic matter<br />

content, substrate type, total metal burden, and concentrations <strong>of</strong> competing ligands, such studies<br />

typically show that Pb has very strong solid-phase partitioning. Partitioning ratios determined by<br />

DPASV generally range from 10 3 to 10 6 in soils in the typical pH range (Sauvé et al., 2000b).<br />

Aualiitia and Pickering (1987) used thin film ASV to compare the relative affinity <strong>of</strong> Pb <strong>for</strong><br />

different inorganic particulates. They reported that Mn(IV) oxides completely adsorbed the Pb,<br />

regardless <strong>of</strong> pH in the range <strong>of</strong> 3 to 9, and had the highest affinity <strong>for</strong> Pb in their study. The<br />

adsorption <strong>of</strong> Pb to pedogenic Fe-oxides, Al-hydroxides, clay minerals, and Fe ores was reported<br />

to be pH-dependent. Sauvé et al. (1998) used DPASV to study the effects <strong>of</strong> organic matter and<br />

pH on Pb adsorption in an orchard soil. They demonstrated that Pb complexation to dissolved<br />

organic matter (DOM) increased Pb solubility, and that 30 to 50% <strong>of</strong> the dissolved Pb was bound<br />

to DOM at pH 3 to 4, while >80% <strong>of</strong> the dissolved Pb was bound to DOM at neutral pH. They<br />

concluded that in most soils, Pb in solution would not be found as Pb 2+ but as bound to DOM.<br />

Sauvé et al. (2000a) compared the relative affinity <strong>of</strong> Pb 2+ <strong>for</strong> synthetic ferrihydrite, leaf<br />

compost, and secondary oxide minerals collected from soils. They reported that the inorganic<br />

mineral phases were more efficient at lowering the amount <strong>of</strong> Pb 2+ that was available in solution<br />

than the leaf compost. Glover et al. (2002) used DPASV in studying the effects <strong>of</strong> time and<br />

organic acids on Pb adsorption to goethite. They found that Pb adsorption to geothite was very<br />

rapid, and remained unchanged after a period <strong>of</strong> about 4 h. <strong>Lead</strong> desorption was found to be<br />

much slower. The presence <strong>of</strong> salicylate appeared to increase the amount <strong>of</strong> Pb that desorbed<br />

from goethite more so than oxalate.<br />

AX7.1.2.2 Tracing the Fate <strong>of</strong> Atmospherically-delivered <strong>Lead</strong> in Terrestrial Ecosystems<br />

Radiogenic Pb isotopes <strong>of</strong>fer a powerful tool <strong>for</strong> separating anthropogenic Pb from natural<br />

Pb derived from mineral weathering (Erel and Patterson, 1994; Erel et al., 1997; Semlali et al.,<br />

2001). This has been particularly useful <strong>for</strong> studying Pb in mineral soil, where geogenic Pb<br />

<strong>of</strong>ten dominates. The three radiogenic stable Pb isotopes ( 206 Pb, 207 Pb, and 208 Pb) have a<br />

heterogeneous distribution in the earth’s crust primarily because <strong>of</strong> the differences in the halflives<br />

<strong>of</strong> their respective parents ( 238 U, T1/2 = 4.7 × 10 9 year; 235 U, T1/2 = 0.7 × 10 9 year; 232 Th,<br />

AX7-31


T1/2 = 14 × 10 9 year). The result is that the ore bodies from which anthropogenic Pb are typically<br />

derived are usually enriched in 207 Pb relative to 206 Pb and 208 Pb when compared with Pb found in<br />

granitic rocks. Graney et al. (1995) analyzed a dated core from Lake Erie, and found that the<br />

206 Pb/ 207 Pb value in sediment deposited in the late 1700s was 1.224, but in 20th-century<br />

sediment, the ratio ranged from 1.223 to 1.197. This shift in the Pb isotopic composition<br />

represents the introduction <strong>of</strong> a significant amount <strong>of</strong> anthropogenic Pb into the environment.<br />

Bindler et al. (1999) and Emmanuel and Erel (2002) analyzed the isotopic composition <strong>of</strong> Pb in<br />

soil pr<strong>of</strong>iles in Sweden and the Czech Republic, respectively, and determined that mineral soils<br />

immediately below the organic horizon had a mixture <strong>of</strong> both anthropogenic and geogenic Pb.<br />

Anthropogenic Pb has been detected relatively deep into the soil pr<strong>of</strong>ile (>25 cm) in Europe,<br />

presumably this represents very “old”( i.e., pre-1900) Pb (Steinnes and Friedland, 2005).<br />

Erel and Patterson (1994) used radiogenic Pb isotopes to trace the movement <strong>of</strong> industrial<br />

Pb from topsoils to groundwaters to streams in a remote mountainous region <strong>of</strong> Yosemite<br />

National Park in Cali<strong>for</strong>nia. They calculated that total 20th-century industrial Pb input to their<br />

study site was approximately 0.4 g Pb m Γ2 . <strong>Lead</strong> concentrations in organic material were highest<br />

in the upper soil horizons, and decreased with depth. During snowmelt, Pb in the snowpack was<br />

mixed with the anthropogenic and geogenic Pb already in the topsoil, and spring melts contained<br />

a mixture <strong>of</strong> anthropogenic and geogenic particulate Pb. During base flows, however, 80% <strong>of</strong><br />

the Pb export from groundwater and streams was from natural granite weathering (Erel and<br />

Patterson, 1994).<br />

Uranium-238 series 210 Pb also provides a tool <strong>for</strong> tracing atmospherically delivered Pb in<br />

soils. After 222 Rn (T1/2 = 3.8 days) is produced from the decay <strong>of</strong> 226 Ra (T1/2 = 1600 years), some<br />

fraction <strong>of</strong> the 222 Rn escapes from rocks and soils to the atmosphere. It then decays relatively<br />

rapidly to 210 Pb (T1/2 = 22.3 years), which has a tropospheric residence time <strong>of</strong> a few weeks<br />

(Koch et al., 1996). Fallout 210 Pb is deposited onto <strong>for</strong>ests via wet and dry deposition, similar to<br />

anthropogenic Pb deposition in <strong>for</strong>ests, and is thus useful as a tracer <strong>for</strong> non-native Pb in soils.<br />

<strong>Lead</strong>-210 is convenient to use <strong>for</strong> calculating the residence time <strong>of</strong> Pb in soil layers, because its<br />

atmospheric and soil fluxes can be assumed to be in steady state at undisturbed sites (Dörr and<br />

Münnich, 1989; Dörr, 1995; Kaste et al., 2003). Atmospheric 210 Pb ( 210 Pbex hereafter, 210 Pb in<br />

“excess” <strong>of</strong> that supported by 222 Rn in the soil) must be calculated by subtracting the amount <strong>of</strong><br />

AX7-32


210 Pb <strong>for</strong>med in soils by the in-situ decay <strong>of</strong> 222 Rn from the total 210 Pb (Moore and Poet, 1976;<br />

Nozaki et al., 1978).<br />

Benninger et al. (1975) measured fallout 210 Pb in soils and streamwater at Hubbard Brook<br />

and at an undisturbed <strong>for</strong>est in Pennsylvania. They estimated atmospheric 210 Pb export in<br />

streamwaters to be


floor) time-series data to evaluate the movement <strong>of</strong> gasoline-derived Pb in the soil pr<strong>of</strong>ile. These<br />

studies have concluded that the distribution <strong>of</strong> Pb in the upper soil horizons has changed over the<br />

past few decades. Yanai et al. (2004) documented a decline in Pb from the Oie horizon between<br />

the late 1970s to the early 1990s in remote <strong>for</strong>est soils in New Hampshire. Johnson et al. (1995a)<br />

and Friedland et al. (1992) demonstrated that some fraction <strong>of</strong> Pb had moved from the O horizon<br />

to the mineral soil during the 1980s at Hubbard Brook and at selected remote sites in the<br />

northeastern United States, respectively. Evans et al. (2005) demonstrated that Pb concentrations<br />

in the litter layer (fresh litter + Oi horizon) sampled in a transect from Vermont to Quebec<br />

decreased significantly between 1979 and 1996, reflecting a decrease in Pb deposition to <strong>for</strong>ests<br />

and upper soil horizons during that time period. Miller et al. (1993) and Wang and Benoit<br />

(1997) used <strong>for</strong>est floor time-series data to model the response time (e folding time, the time it<br />

takes a reservoir to decrease to the 1/e, (ca. 37%) <strong>of</strong> its original amount) <strong>of</strong> Pb in the <strong>for</strong>est floor.<br />

Miller et al. (1993) calculated O horizon response times <strong>of</strong> 17 years <strong>for</strong> the northern hardwood<br />

<strong>for</strong>est and 77 years in the spruce-fir zone on Camel’s Hump Mountain in Vermont. Wang and<br />

Benoit (1997) determined that the O horizon would reach steady state with respect to Pb<br />

(1.3 µg g Γ1 Pb) by 2100. Both suggested that the vertical movement <strong>of</strong> organic particles<br />

dominated Pb transport in the soil pr<strong>of</strong>ile.<br />

AX7.1.2.3 Inputs/Outputs <strong>of</strong> Atmospherically-delivered <strong>Lead</strong> in Terrestrial Ecosystems<br />

The concentration <strong>of</strong> Pb in contemporary rainfall in the mid-Atlantic and northeastern<br />

United States is on the order <strong>of</strong> 0.5 to 1 µg/L (Wang et al., 1995; Kim et al., 2000; Scudlark<br />

et al., 2005). Long-term trends in nine elemental concentrations (including Pb) in wet deposition<br />

were measured on the Delmarva Peninsula near Lewes, Delaware, over the period from 1982 to<br />

1989 (Figure AX7-1.2.1) (Scudlark et al., 1994). Of the nine elements measured, only Pb (and<br />

possibly Al and Cd), indicated a decreasing trend over time (3 µg/L in 1982 to


Figure AX7-1.2.1. Long-term (1982-1989) annual trends in lead concentrations (µg/L) in<br />

Lewes, Delaware precipitation.<br />

Source: Scudlark et al. (1994)<br />

The role <strong>of</strong> dry deposition in the total deposition <strong>of</strong> Pb to terrestrial ecosystems is not<br />

constrained well. Researchers have estimated that dry deposition accounts <strong>for</strong> anywhere<br />

between 10 to >90% <strong>of</strong> total Pb deposition (Galloway et al., 1982; Wu et al., 1994; Sabin et al.,<br />

2005). Migon et al. (1997) found total, wet, and dry Pb deposition to be 8.6, 1.6 and<br />

7.0 µg/m2/d, respectively, over the Ligurian Sea, France. Dry deposition velocities were<br />

estimated at approximately 0.2 cm/sec, similar to anthropogenic element deposition velocities<br />

measured at remote lakes around Lake Michigan (Yi et al., 2001). Yi et al. (2001) found that dry<br />

deposition velocities <strong>for</strong> elements were correlated with particle concentrations in the following<br />

order: coarse > total particle > fine particle. Refer to Table 2-21 <strong>for</strong> additional in<strong>for</strong>mation on<br />

dry, wet, and total Pb deposition velocities and fluxes.<br />

Arid environments appear to have a much higher fraction <strong>of</strong> dry deposition: total<br />

deposition (Sabin et al., 2005). Furthermore, it is possible that Clean <strong>Air</strong> Act Legislation enacted<br />

in the late 1970s preferentially reduced Pb associated with fine particles, so the relative<br />

AX7-35


contributions <strong>of</strong> dry deposition may have changed in the last few decades. If the major source <strong>of</strong><br />

Pb to a terrestrial ecosystem is resuspended particulates from transportation corridors, then the<br />

particle size fraction that dominates deposition may be relatively coarse (>50 µm) relative to<br />

other atmospheric sources (Pirrone et al., 1995; Sansalone et al., 2003).<br />

Total contemporary loadings to terrestrial ecosystems are approximately 1 to 2 mg m Γ2<br />

year Γ1 (Wu et al., 1994; Wang et al., 1995; Simonetti et al., 2000; Sabin et al., 2005). This is a<br />

relatively small annual flux <strong>of</strong> Pb if compared to the reservoir <strong>of</strong> approximately 0.5 to 4 g m Γ2 <strong>of</strong><br />

gasoline-derived Pb that is already in surface soils over much <strong>of</strong> the United States (Friedland<br />

et al., 1992; Miller and Friedland, 1994; Erel and Patterson, 1994; Marsh and Siccama, 1997;<br />

Yanai et al., 2004; Johnson et al., 2004; Evans et al., 2005). While vegetation can play an<br />

important role in sequestering Pb from rain and dry deposition (Russell et al., 1981), direct<br />

uptake <strong>of</strong> Pb from soils by plants appears to be low (Klaminder et al., 2005). High elevation<br />

areas, particularly those near the base level <strong>of</strong> clouds <strong>of</strong>ten have higher burdens <strong>of</strong> atmospheric<br />

contaminants (Siccama, 1974). A Pb deposition model by Miller and Friedland (1994) predicted<br />

2.2 and 3.5 g Pb m Γ2 deposition <strong>for</strong> the 20th century in the deciduous zone (600 m) and the<br />

coniferous zone (1000 m), respectively. More recently, Kaste et al. (2003) used radiogenic<br />

isotope measurements on the same mountain to confirm higher loadings at higher elevation.<br />

They measured 1.3 and 3.4 g gasoline-derived Pb m Γ2 in the deciduous zone and coniferous<br />

zones, respectively. Higher atmospheric Pb loadings to higher elevations are attributed to<br />

(1) the higher leaf area <strong>of</strong> coniferous species, which are generally more prevalent at high<br />

elevation; (2) higher rainfall at higher elevation; and (3) increased cloudwater impaction at high<br />

elevation (Miller et al., 1993).<br />

Although inputs <strong>of</strong> Pb to ecosystems are currently low, Pb export from watersheds via<br />

groundwater and streams is substantially lower than inputs. There<strong>for</strong>e, even at current input<br />

levels, watersheds are accumulating industrial Pb. However, burial/movement <strong>of</strong> lead over time<br />

down into lower soil/sediment layers also tends to sequester it away from more biologically<br />

active parts <strong>of</strong> the watershed (unless later disturbed or redistributed, e.g., by flooding, dredging,<br />

etc.). Seeps and streams at the HBEF have Pb concentrations on the order <strong>of</strong> 10 to 30 pg Pb g Γ1<br />

(Wang et al., 1995). At a remote valley in the Sierra Nevada, Pb concentrations in streamwaters<br />

were on the order <strong>of</strong> 15 pg Pb g Γ1 (Erel and Patterson, 1994). Losses <strong>of</strong> Pb from soil horizons are<br />

assumed to be via particulates (Dörr and Münnich, 1989; Wang and Benoit, 1996, 1997). Tyler<br />

AX7-36


(1981) noted that Pb losses from a spruce <strong>for</strong>est A-horizon soil in Sweden were influenced by<br />

season; with highest Pb fluxes being observed during warm, wet months. He suggested that<br />

DOC production and Pb movement were tightly linked.<br />

Surface soils across the United States are enriched in Pb relative to levels expected from<br />

solely natural geogenic inputs (Friedland et al., 1984; Herrick and Friedland, 1990; Francek,<br />

1992; Erel and Patterson, 1994; Marsh and Siccama, 1997; Yanai et al., 2004; Murray et al.,<br />

2004). While some <strong>of</strong> this contaminant Pb is attributed to paint, salvage yards, shooting ranges,<br />

and the use <strong>of</strong> Pb arsenate as a pesticide in localized areas (Francek, 1997), Pb contamination <strong>of</strong><br />

surface soils is essentially ubiquitous because <strong>of</strong> atmospheric pollution associated with metal<br />

smelting and production, the combustion <strong>of</strong> fossil fuels, and waste incineration (Newhook et al.,<br />

2003; Polissar et al., 2001). Surface soils in Michigan, <strong>for</strong> example, typically range from 8 to<br />

several hundred ppm Pb (Francek, 1992; Murray et al., 2004). Soils collected and analyzed<br />

beneath 50 cm in Michigan, however, range only from 4 to 60 ppm Pb (Murray et al., 2004).<br />

In remote surface soils from the Sierra Nevada Mountains, litter and upper soil horizons are 20 to<br />

40 ppm Pb, and approximately 75% <strong>of</strong> this Pb has been attributed to atmospheric deposition<br />

during the 20th century (Erel and Patterson, 1994). Repeated sampling <strong>of</strong> the <strong>for</strong>est floor<br />

(O horizon) in the northeastern United States demonstrates that the organic layer has retained<br />

much <strong>of</strong> the Pb load deposited on ecosytems during the 20th century. Total Pb deposition during<br />

the 20th century has been estimated at 1 to 3 g Pb m Γ2 , depending on elevation and proximity to<br />

urban areas (Miller and Friedland, 1994; Johnson et al., 1995a). Forest floors sampled during the<br />

1980s and 1990s, and in early 2000 had between 0.7 and 2 g Pb m Γ2 (Friedland et al., 1992;<br />

Miller and Friedland, 1994; Johnson et al., 1995a; Kaste et al., 2003; Yanai et al., 2004; Evans<br />

et al., 2005). The pool <strong>of</strong> Pb in above- and below-ground biomass at the HBEF is on the order <strong>of</strong><br />

0.13 g Pb m Γ2 (Johnson et al., 1995a).<br />

The amount <strong>of</strong> Pb that has leached into mineral soil appears to be on the order <strong>of</strong> 20 to<br />

50% <strong>of</strong> the total anthropogenic Pb deposition. Kaste et al. (2003) and Miller and Friedland<br />

(1994) demonstrated that Pb loss from the <strong>for</strong>est floor at Camel’s Hump Mountain in Vermont<br />

depended on elevation. While the mineral soil in the deciduous <strong>for</strong>est had between 0.4 and 0.5 g<br />

Pb m Γ2 (out <strong>of</strong> 1 to 2 g Pb m Γ2 in the total soil pr<strong>of</strong>ile), at higher elevations the thicker coniferous<br />

<strong>for</strong>est floor retained more than 90% <strong>of</strong> the total Pb deposition (Kaste et al., 2003). Johnson et al.<br />

(1995a) determined that the <strong>for</strong>est floor at HBEF in the mid-1980s had about 0.75 g Pb m Γ2 .<br />

AX7-37


Compared to their estimated 20th-century atmospheric Pb deposition <strong>of</strong> 0.9 g Pb m Γ2 , the <strong>for</strong>est<br />

floor has retained 83% <strong>of</strong> the atmospheric Pb loadings (Johnson et al., 1995a). Johnson et al.<br />

(2004) noted that gasoline-derived Pb was a significant component <strong>of</strong> the labile Pb at the HBEF.<br />

They calculated that Pb fluxes to the HBEF by atmospheric pollution were essentially equivalent<br />

to the Pb released by mineral weathering over the past 12,000 years. Marsh and Siccama (1997)<br />

used the relatively homogenous mineral soils underneath <strong>for</strong>merly plowed land in Rhode Island,<br />

New Hampshire and Connecticut to assess the depth-distribution <strong>of</strong> atmospheric Pb. They<br />

reported that 65% <strong>of</strong> the atmospheric Pb deposited during the 20th century is in the mineral soil<br />

and 35% is in the <strong>for</strong>est floor. At their remote study site in the Sierra Nevada Mountains, Erel<br />

and Patterson (1994) reported that most <strong>of</strong> the anthropogenic Pb was associated with the humus<br />

fraction <strong>of</strong> the litter layer and soils sampled in the upper few cm.<br />

Atmospherically delivered Pb is probably present in ecosystems in a variety <strong>of</strong> different<br />

biogeochemical phases. A combination <strong>of</strong> Pb adsorbtion processes and the precipitation <strong>of</strong> Pb<br />

minerals will typically keep dissolved Pb species low in soil solution, surface waters, and<br />

streams (Sauvé et al., 2000a; Jackson et al., 2005). While experimental and theoretical evidence<br />

suggest that the precipitation <strong>of</strong> inorganic Pb phases and the adsorption <strong>of</strong> Pb on inorganic<br />

phases can control the biogeochemistry <strong>of</strong> contaminant Pb (Nriagu, 1974; Ruby et al., 1994;<br />

Jackson et al., 2005), the influence <strong>of</strong> organic matter on the biogeochemistry <strong>of</strong> Pb in terrestrial<br />

ecosystems cannot be ignored in many systems. Organic matter can bind to Pb, preventing Pb<br />

migration and the precipitation <strong>of</strong> inorganic phases (Manceau et al., 1996; Xia et al., 1997; Lang<br />

and Kaupenjohann, 2003). As the abundance <strong>of</strong> organic matter declines in soil, Pb adsorption to<br />

inorganic soil minerals and the direct precipitation <strong>of</strong> Pb phases may dominate the<br />

biogeochemistry <strong>of</strong> Pb in terrestrial ecosystems (Ostergren et al., 2000a,b; Sauvé et al., 2000a).<br />

Conclusions<br />

Advances in technology since the 1986 <strong>Lead</strong> AQCD have allowed <strong>for</strong> a quantitative<br />

determination <strong>of</strong> the mobility, distribution, uptake, and fluxes <strong>of</strong> atmospherically delivered Pb in<br />

ecosystems. Among other things, these studies have shown that industrial Pb represents a<br />

significant fraction <strong>of</strong> total labile Pb in watersheds. Selective chemical extractions and<br />

synchrotron-based X-ray studies have shown that industrial Pb can be strongly sequestered by<br />

organic matter and by secondary minerals such as clays and oxides <strong>of</strong> Al, Fe, and Mn. Some <strong>of</strong><br />

AX7-38


these studies have provided compelling evidence that the biomineralization <strong>of</strong> Pb phosphates by<br />

soil organisms can play an important role in the biogeochemistry <strong>of</strong> Pb. Surface soils sampled<br />

relatively recently demonstrate that the upper soil horizons (O + A horizons) are retaining most<br />

<strong>of</strong> the industrial Pb burden introduced to the systems during the 20th century. The migration and<br />

biological uptake <strong>of</strong> Pb in ecosystems is relatively low. The different biogeochemical behaviors<br />

<strong>of</strong> Pb reported by various studies may be a result <strong>of</strong> the many different analytical techniques<br />

employed, or they may be a result <strong>of</strong> natural variability in the behavior <strong>of</strong> Pb in different<br />

systems.<br />

<strong>Lead</strong> Uptake into Plants<br />

Plants take up Pb via their foliage and through their root systems (U.S. Environmental<br />

Protection Agency, 1986a; Påhlsson, 1989). Surface deposition <strong>of</strong> Pb onto plants may represent<br />

a significant contribution to the total Pb in and on the plant, as has been observed <strong>for</strong> plants near<br />

smelters and along roadsides (U.S. Environmental Protection Agency, 1986a). The importance<br />

<strong>of</strong> atmospheric deposition on above-ground plant Pb uptake is well-documented (Dalenberg and<br />

Van Driel, 1990; Jones and Johnston, 1991; Angelova et al., 2004). Data examined from<br />

experimental grassland plots in southeast England demonstrated that atmospheric Pb is a greater<br />

contributor than soil-derived Pb in crop plants and grasses (Jones and Johnston, 1991). A study<br />

by Dalenberg and Van Driel (1990) showed that 75 to 95% <strong>of</strong> the Pb found in field-grown test<br />

plants (i.e., the leafy material <strong>of</strong> grass, spinach, and carrot; wheat grain; and straw) was from<br />

atmospheric deposition. Angelova et al. (2004) found that tobacco grown in an industrial area<br />

accumulated significant amounts <strong>of</strong> Pb from the atmosphere, although uptake from soil was also<br />

observed. The concentration <strong>of</strong> Pb in tobacco seeds was linearly related to the concentration <strong>of</strong><br />

Pb in the exchangeable and carbonate-bound fractions <strong>of</strong> soil, as measured using sequential<br />

extraction (Angelova et al., 2004). <strong>Lead</strong> in soil is more significant when considering uptake into<br />

root vegetables (e.g., carrot, potato), since, as was noted in the 1986 <strong>Lead</strong> AQCD (U.S.<br />

Environmental Protection Agency, 1986a), most Pb remains in the roots <strong>of</strong> plants.<br />

There are two possible mechanisms (symplastic or apoplastic) by which Pb may enter the<br />

root <strong>of</strong> a plant. The symplastic route is through the cell membranes <strong>of</strong> root hairs; this is the<br />

mechanism <strong>of</strong> uptake <strong>for</strong> water and nutrients. The apoplastic route is an extracellular route<br />

between epidermal cells into the intercellular spaces <strong>of</strong> the root cortex. Previously, Pb was<br />

AX7-39


thought to enter the plant via the symplastic route, probably by transport mechanisms similar to<br />

those involved in the uptake <strong>of</strong> calcium or other divalent cations (i.e., transpirational mass flow,<br />

diffusion, or active transport). However, it also had been speculated that Pb may enter the plant<br />

via the apoplastic route (U.S. Environmental Protection Agency, 1986a). Sieghardt (1990)<br />

determined that the mechanism <strong>of</strong> Pb uptake was via the symplastic route only and that the<br />

apoplastic pathway <strong>of</strong> transport was stopped in the primary roots by the endodermis. He studied<br />

the uptake <strong>of</strong> Pb into two plants, Minuartia verna (moss sandwort) and Silene vulgaris (bladder<br />

campion) that colonize metal-contaminated sites. In the roots <strong>of</strong> both plants, Pb was found<br />

mainly in the root cortex. Active ion uptake was required to transport the Pb into the stele and<br />

then into the shoots <strong>of</strong> the plant (Sieghardt, 1990).<br />

Although some plants translocate more Pb to the shoots than others, most Pb remains in<br />

the roots <strong>of</strong> plants. Two mechanisms have been proposed to account <strong>for</strong> this relative lack <strong>of</strong><br />

translocation to the shoots: (1) Pb may be deposited within root cell wall material, or (2) Pb may<br />

be sequestered within root cell organelles (U.S. Environmental Protection Agency, 1986a).<br />

Påhlsson (1989) noted that plants can accumulate large quantities <strong>of</strong> Pb from the soil but that<br />

translocation to shoots and leaves is limited by the binding <strong>of</strong> Pb ions at root surfaces and cell<br />

walls. In a study by Wierzbicka (1999), 21 different plant species were exposed to Pb 2+ in the<br />

<strong>for</strong>m <strong>of</strong> Pb-chloride. The plant species included cucumber (Cucumis sativus), soy bean (Soja<br />

hispida), bean (Phaseolus vulgaris), rapeseed (Brassica napus), rye (Secale cereale), barley<br />

(Hordeum vulgare), wheat (Triticum vulgare), radish (Raphanus sativus), pea (Pisum sativum),<br />

maize (Zea mays), onion (Allium cepa), lupine (Lupinus luteus), bladder campion (Silene<br />

vulgaris), Buckler mustard (Biscutella laevigata), and rough hawkbit (Leontodon hispidus).<br />

Although, the amount <strong>of</strong> Pb taken up by the plant varied with species, over 90% <strong>of</strong> absorbed Pb<br />

was retained in the roots. Only a small amount <strong>of</strong> Pb was translocated (~2 to 4%) to the shoots<br />

<strong>of</strong> the plants. <strong>Lead</strong> in roots was present in the deeper layers <strong>of</strong> root tissues (in particular, the root<br />

cortex) and not only on the root surface. There was no correlation between Pb tolerance<br />

(measured as root mass increase expressed as a percentage <strong>of</strong> controls) and either root or shoot<br />

tissue concentrations (Wierzbicka, 1999). The study by Wierzbicka (1999) was the first to report<br />

that plants developing from bulbs, in this case the onion, were more tolerant to Pb than plants<br />

developing from seeds. This tolerance was assumed to be related to the large amounts <strong>of</strong> Pb that<br />

were transported from the roots and stored in the bulb <strong>of</strong> the plant (Wierzbicka, 1999).<br />

AX7-40


Uptake <strong>of</strong> Pb from soil into plants was modeled as part <strong>of</strong> Eco-SSL development (U.S.<br />

Environmental Protection Agency, 2005a). The relationship derived between Pb in the soil and<br />

Pb in a plant was taken from Bechtel Jacobs Company (BJC) (1998) and is as follows:<br />

Ln(Cp) = 0.561 * Ln(Csoil) − 1.328<br />

AX7-41<br />

(AX7-1)<br />

where Cp is the concentration <strong>of</strong> Pb in the plant (dry weight) and Csoil is the concentration <strong>of</strong> Pb<br />

in the soil. This equation recognizes that the ratio <strong>of</strong> Pb concentration in plant to Pb<br />

concentration in soil is not constant.<br />

Invertebrates<br />

There was no clear evidence suggesting a differential uptake <strong>of</strong> Pb into different species<br />

<strong>of</strong> earthworm (Lumbricus terrestris, Aporrectodea rosea, and A. caliginosa) collected around a<br />

smelter site near Avonmouth, England (Spurgeon and Hopkin, 1996a). This is in contrast to Pižl<br />

and Josens (1995) and Terhivuo et al. (1994) who found Aporrectodea spp. accumulated more<br />

Pb than Lumbricus. The authors suggested that these differences could be due to different<br />

feeding behaviors, as Lumbricus feeds on organic material and Apporectodea species are<br />

geophagus, ingesting large amounts <strong>of</strong> soil during feeding. The differences between species also<br />

may be related to differing efficiencies in excretory mechanisms (Pižl and Josens, 1995).<br />

However, the interpretation <strong>of</strong> species difference is complicated by a number <strong>of</strong> potentially<br />

confounding variables, such as soil characteristics (e.g., calcium or other nutrient levels)<br />

(Pižl and Josens, 1995).<br />

The bioaccumulation <strong>of</strong> Pb from contaminated soil was tested using the earthworm<br />

Eisenia fetida, and the amount <strong>of</strong> Pb accumulated did not change significantly until the<br />

concentration within soil reached 5000 mg/kg (Davies et al., 2003). This coincided with the<br />

lowest soil concentrations at which earthworm mortality was observed. The ratio <strong>of</strong> the<br />

concentration <strong>of</strong> Pb in worms to the concentration in soil decreased from 0.03 at 100 mg/kg to<br />

0.001 at 3000 mg/kg, but then increased quickly to 0.02 at 5000 mg/kg. The authors concluded<br />

that earthworms exhibit regulated uptake <strong>of</strong> Pb at levels <strong>of</strong> low contamination (


soil was not allowed to equilibrate following the addition <strong>of</strong> Pb and prior to the addition <strong>of</strong> the<br />

test organisms. This may have resulted in an increased bioavailability and overestimated Pb<br />

toxicity relative to actual environmental conditions (Davies et al., 2003). See the discussion in<br />

Section AX7.1.2 on the effects <strong>of</strong> aging on Pb sorption processes.<br />

Lock and Janssen (2002) and Bongers et al. (2004) found that Pb-nitrate was more toxic<br />

than Pb-chloride to survival and reproduction <strong>of</strong> the springtail Folsomia candida. However,<br />

percolation (removal <strong>of</strong> the chloride or nitrate counterion) caused a significant decrease in Pb-<br />

nitrate toxicity such that there was no difference in toxicity once the counterion was removed<br />

(Bongers et al., 2004). No change in toxicity was observed <strong>for</strong> Pb-chloride once the chloride<br />

was removed from the soil. Bongers et al. (2004) suggested that the nitrate ion was more toxic<br />

than the chloride ion to springtails.<br />

Uptake <strong>of</strong> Pb from soil into earthworms was also modeled as part <strong>of</strong> Eco-SSL<br />

development (U.S. Environmental Protection Agency, 2005a). The relationship derived between<br />

Pb in the soil and Pb in an earthworm was taken from Sample et al. (1999) and is as follows:<br />

Ln(Cworm) = 0.807 * Ln(Csoil) – 0.218<br />

where Cworm is the concentration <strong>of</strong> Pb in the earthworm (dry weight) and Csoil is the<br />

AX7-42<br />

(AX7-2)<br />

concentration <strong>of</strong> Pb in the soil. This equation recognizes that the ratio <strong>of</strong> Pb concentration in<br />

worm to Pb concentration in soil is not constant.<br />

Wildlife<br />

Research has been conducted to determine what Pb concentrations in various organs<br />

would be indicative <strong>of</strong> various levels <strong>of</strong> effects. For example, Franson (1996) compiled data to<br />

determine what residue levels were consistent with three levels <strong>of</strong> effects in Falconi<strong>for</strong>mes (e.g.,<br />

falcons, hawks, eagles, kestrels, ospreys), Columbi<strong>for</strong>mes (e.g., doves, pigeons), and Galli<strong>for</strong>mes<br />

(e.g., turkey, pheasant, partridge, quail, chickens). The three levels <strong>of</strong> effect were (1) subclinical,<br />

which are physiological effects only, such as the inhibition <strong>of</strong> δ-aminolevulinic acid dehydratase<br />

(ALAD; see Section AX7.1.3.3); (2) toxic, a threshold level marking the initiation <strong>of</strong> clinical<br />

signs, such as anemia, lesions in tissues, weight loss, muscular incoordination, green diarrhea,<br />

and anorexia; and (3) compatible with death, an approximate threshold value associated with


death in field, captive, and/or experimental cases <strong>of</strong> Pb poisoning. The tissue Pb levels<br />

associated with these levels <strong>of</strong> effects are presented in Table AX7-1.2.1.<br />

Table AX7-1.2.1. Tissue <strong>Lead</strong> Levels in Birds Causing Effects<br />

(taken from Franson, 1996)<br />

Blood<br />

Liver<br />

Kidney<br />

Order<br />

Falconi<strong>for</strong>mes<br />

(µg/dL)<br />

(ppm wet wt.) (ppm wet wt.)<br />

Subclinical 0.2 – 1.5 2 – 4 2 – 5<br />

Toxic >1 >3 >3<br />

Compatible with death<br />

Columbi<strong>for</strong>mes<br />

>5 >5 >5<br />

Subclinical 0.2 – 2.5 2 – 6 2 – 20<br />

Toxic >2 >6 >15<br />

Compatible with death<br />

Galli<strong>for</strong>mes<br />

>10 >20 >40<br />

Subclinical 0.2 – 3 2 – 6 2 – 20<br />

Toxic >5 >6 >15<br />

Compatible with death >10 >15 >50<br />

Tissue residue levels below the subclinical levels in Table AX7-1.2.1 should be<br />

considered “background” (Franson, 1996). Levels in the subclinical range are indicative <strong>of</strong><br />

potential injury from which the bird would probably recover if Pb exposure was terminated.<br />

Toxic residues could lead to death. Residues above the compatible-with-death threshold are<br />

consistent with Pb-poisoning mortality (Franson, 1996). Additional in<strong>for</strong>mation on residue<br />

levels <strong>for</strong> Passeri<strong>for</strong>mes (e.g., sparrows, starlings, robins, cowbirds), Charadrii<strong>for</strong>mes (e.g., gulls,<br />

terns), Grui<strong>for</strong>mes (e.g., cranes), Ciconi<strong>for</strong>mes (e.g., egrets), Gavi<strong>for</strong>mes (e.g., loons), and<br />

Strigi<strong>for</strong>mes (e.g., owls) is available in Franson (1996). Scheuhammer (1989) found blood Pb<br />

concentrations <strong>of</strong> between 0.18 and 0.65 µg/mL in mallards corresponded to conditions<br />

associated with greater than normal exposure to Pb but that should not be considered Pb<br />

poisoning.<br />

AX7-43


<strong>Lead</strong> concentrations in various tissues <strong>of</strong> mammals also have been correlated with toxicity<br />

(Ma, 1996). The tissues commonly analysed <strong>for</strong> Pb are blood, liver, and kidney. Typical<br />

baseline levels <strong>of</strong> blood Pb are approximately 4 to 8 µg/dL <strong>for</strong> small mammals, and 2 to 6 µg/dL<br />

<strong>for</strong> mature cattle. Typical baseline levels <strong>of</strong> Pb in liver are 1 to 2 mg/kg dw <strong>for</strong> small mammals.<br />

Typical baseline levels <strong>of</strong> Pb in kidney are 0.2 to 1.5 mg/kg dw <strong>for</strong> mice and voles, but shrews<br />

typically have higher baseline levels <strong>of</strong> 3 to 19 mg/kg dw. Ma (1996) concluded that Pb levels<br />

less than 5 mg/kg dw in liver and 10 mg/kg dw in kidney were not associated with toxicity, but<br />

that levels greater than 5 mg/kg dw in liver and greater than 15 mg/kg dw in kidney could be<br />

taken as a chemical biomarker <strong>of</strong> toxic exposure to Pb in mammals. Humphreys (1991) noted<br />

that the concentrations <strong>of</strong> Pb in liver and kidney can be elevated in animals with normal blood Pb<br />

concentrations (and without exhibiting clinical signs <strong>of</strong> Pb toxicity), because Pb persists in these<br />

organs longer than in blood.<br />

Uptake <strong>of</strong> Pb from soil into small mammals was also modeled as part <strong>of</strong> Eco-SSL<br />

development (U.S. Environmental Protection Agency, 2005a). The relationship derived between<br />

Pb in the soil and Pb in the whole-body <strong>of</strong> a small mammal was taken from Sample et al. (1998)<br />

and is as follows:<br />

Ln(Cmammal) = 0.4422 * Ln(Csoil) + 0.0761<br />

Where Cmammal is the concentration <strong>of</strong> Pb in small mammals (dry weight) and Csoil is the<br />

concentration <strong>of</strong> Pb in the soil. Similar to the uptake equations <strong>for</strong> plants (Eq. 8-1) and<br />

earthworms (Eq 8-2), the equation <strong>for</strong> mammalian uptake recognizes that the ratio <strong>of</strong> Pb<br />

concentration in small mammals to Pb concentration in soil is not constant.<br />

AX7.1.2.4 Resistance Mechanisms<br />

AX7-44<br />

(AX7-3)<br />

Many mechanisms related to heavy metal tolerance in plants and invertebrates have been<br />

described, including avoidance (i.e., root redistribution, food rejection), exclusion (i.e., selective<br />

uptake and translocation), immobilization at the plant cell wall, and excretion (i.e., foliar<br />

leakage, moulting) (Tyler et al., 1989; Patra et al., 2004). The following section reviews the<br />

recent literature on the resistance mechanisms <strong>of</strong> plants and invertebrates through mitigation <strong>of</strong><br />

Pb (1) toxicity or (2) exposure.


Detoxification Mechanisms<br />

<strong>Lead</strong> sequestration in cell walls may be the most important detoxification mechanism in<br />

plants. Calcium may play a role in this detoxification by regulating internal Pb concentrations<br />

through the <strong>for</strong>mation <strong>of</strong> Pb-containing precipitates in the cell wall (Antosiewicz, 2005). Yang<br />

et al. (2000) screened 229 varieties <strong>of</strong> rice (Oryza sativa) <strong>for</strong> tolerance or sensitivity to Pb and<br />

found that the oxalate content in the root and root exudates was increased in Pb-tolerant varieties.<br />

The authors suggested that the oxalate reduced Pb bioavailability, and that this was an important<br />

tolerance mechanism (Yang et al., 2000). Sharma et al. (2004) found Pb-sulfur and Pb-sulfate in<br />

the leaves, and Pb-sulfur in the roots <strong>of</strong> Sesbania drummondii (Rattlebox Drummond), a Pb<br />

hyperaccumulator plant grown in Pb-nitrate solution. They hypothesized that these sulfur<br />

ligands were indicative <strong>of</strong> glutathione and phytochelatins, which play a role in heavy metal<br />

homeostasis and detoxification (Sharma et al., 2004).<br />

Sea pinks (Armeria maritima) grown on a metal-contaminated site (calamine spoils more<br />

than 100 years old) accumulated 6Η the concentrations <strong>of</strong> Pb in brown (dead and withering)<br />

leaves than green leaves (Szarek-Lukaszewska et al., 2004). The concentration <strong>of</strong> Pb in brown<br />

leaves was similar to that in roots. This greater accumulation <strong>of</strong> Pb into older leaves was not<br />

observed in plants grown hydroponically in the laboratory. The authors hypothesized that this<br />

sequestering <strong>of</strong> Pb into the oldest leaves was a detoxification mechanism (Szarek-Lukaszewska<br />

et al., 2004).<br />

Terrestrial invertebrates also mitigate Pb toxicity. Wilczek et al. (2004) studied two<br />

species <strong>of</strong> spider, the web-building Agelena labyrinthica, and the active hunter wolf spider<br />

Pardosa lugubris. The activity <strong>of</strong> metal detoxifying enzymes (via the glutathione metabolism<br />

pathways) was greater in A. labyrinthica and in females <strong>of</strong> both species (Wilczek et al., 2004).<br />

Marinussen et al. (1997) found that earthworms can excrete 60% <strong>of</strong> accumulated Pb very<br />

quickly once exposure to Pb-contaminated soils has ended. However, the remainder <strong>of</strong> the body<br />

burden is not excreted, possibly due to the storage <strong>of</strong> Pb in waste nodules that are too large to be<br />

excreted (Hopkin, 1989). Gintenreiter et al. (1993) found that Lepidoptera larvae (in this case,<br />

the gypsy moth Lymantria dispar) eliminated Pb, to some extent, in the meconium (the fluid<br />

excreted shortly after emergence from the chrysalis).<br />

<strong>Lead</strong>, in the <strong>for</strong>m <strong>of</strong> pyromorphite (Pb5(PO4)3Cl), was localized in the anterior pharynx<br />

region <strong>of</strong> the nematode Ceanorhabditis elegans (Jackson et al., 2005). The authors hypothesized<br />

AX7-45


that the nematode may detoxify Pb via its precipitation into pyromorphite, which is relatively<br />

insoluble (Jackson et al., 2005).<br />

Avoidance Response<br />

Studies with soil invertebrates hypothesize that these organisms may avoid soil with high<br />

Pb concentrations. For example, Bengtsson et al. (1986) suggested that the lower Pb<br />

concentrations in earthworm tissues may be a result <strong>of</strong> lowered feeding activity <strong>of</strong> worms at<br />

higher Pb concentrations in soil.<br />

AX7.1.2.5 Physiological Effects <strong>of</strong> <strong>Lead</strong><br />

Several studies have measured decreased blood ALAD activity in birds and mammals<br />

exposed to Pb (U.S. Environmental Protection Agency, 1986a). Recent studies on the<br />

physiological effects <strong>of</strong> Pb to consumers have focused on heme synthesis (as measured by<br />

ALAD activity and protoporphyrin concentration), lipid peroxidation, and production <strong>of</strong> fatty<br />

acids. Effects on growth are covered in Section AX7.1.4.<br />

Biochemically, Pb adversely affects hemoglobin synthesis in birds and mammals. Early<br />

indicators <strong>of</strong> Pb exposure in birds and mammals include decreased blood ALAD concentrations<br />

and increased protoporphyrin IX activity. The effects <strong>of</strong> Pb on blood parameters and the use <strong>of</strong><br />

these parameters as sensitive biomarkers <strong>of</strong> exposure has been well documented (Eisler, 1988;<br />

U.S. Environmental Protection Agency, 2005b). However, the linkage between these<br />

biochemical indicators and ecologically relevant effects is less well understood. Low-level<br />

inhibition <strong>of</strong> ALAD is not generally considered a toxic response, because this enzyme is thought<br />

to be present in excess concentrations; rather, it may simply indicate that the organism has<br />

recently been exposed to Pb (Henny et al., 1991).<br />

Schlick et al. (1983) studied ALAD inhibition in mouse bone marrow and erythrocytes.<br />

They estimated that an absorbed dose <strong>of</strong> between 50 and 100 µg Pb-acetate/kg body weight per<br />

day would result in long-term inhibition <strong>of</strong> ALAD.<br />

Beyer et al. (2000) related blood Pb to sublethal effects in waterfowl along the<br />

Coeur d=Alene River near a mining site in Idaho. The sublethal effects measured included,<br />

among others, red blood cell ALAD activity and protoporphyrin levels in the blood. As found in<br />

other studies, ALAD activity was the most sensitive indicator <strong>of</strong> Pb exposure, decreasing to 3%<br />

AX7-46


<strong>of</strong> the reference value at a blood Pb concentration <strong>of</strong> 0.68 mg/kg ww (wet weight).<br />

Protoporphyrin concentrations showed a 4.2-fold increase at this same concentration.<br />

Henny et al. (1991) studied osprey along the Coeur d=Alene River. There were no<br />

observations <strong>of</strong> death, behavioral abnormalities, or reduced productivity related to Pb exposure,<br />

although inhibition <strong>of</strong> blood ALAD and increased protoporphyrin concentrations were measured<br />

in ospreys. Henny et al. (1991) hypothesized that no impacts to osprey were observed, even<br />

though swan mortality was documented in the area because swans feed at a lower trophic level<br />

(i.e., Pb does not biomagnify, and thus is found at higher concentrations in lower trophic level<br />

organisms).<br />

H<strong>of</strong>fman et al. (2000a) also studied the effects <strong>of</strong> Coeur d’Alene River sediment on<br />

waterfowl, focusing on mallard ducklings <strong>for</strong> 6 weeks after hatching. The study revealed that a<br />

90% reduction in ALAD activity and a greater than 3-fold increase in protoporphyrin<br />

concentration occurred when blood Pb reached a concentration <strong>of</strong> 1.41 mg/kg ww as a result <strong>of</strong><br />

the ducklings being fed a diet composed <strong>of</strong> 12% sediment (3449 mg/kg Pb). Those ducklings<br />

fed a diet composed <strong>of</strong> 24% sediment were found to have a mean blood Pb concentration <strong>of</strong><br />

2.56 mg/kg ww and a greater than 6-fold increase in protoporphyrin concentration. H<strong>of</strong>fman<br />

et al. (2000b) also studied Canada Geese (Branta canadensis) goslings in a similar fashion.<br />

The results revealed that, while blood Pb concentrations in goslings were approximately half<br />

(0.68 mg/kg ww) <strong>of</strong> those found in ducklings under the same conditions (12% diet <strong>of</strong><br />

3449 mg/kg sediment Pb), goslings showed an increased sensitivity to Pb exposure. Goslings<br />

experienced a 90% reduction in ALAD activity and a 4-fold increase in protoporphyrin<br />

concentration, similar to conditions found in the ducklings, although blood Pb concentrations<br />

were half those found in the ducklings. More serious effects were seen in the goslings when<br />

blood Pb reached 2.52 mg/kg, including decreased growth and mortality.<br />

Redig et al. (1991) reported a hawk LOAEL (lowest observed adverse effect level) <strong>of</strong><br />

0.82 mg/kg-day <strong>for</strong> effects on heme biosynthetic pathways. <strong>Lead</strong> dosages as high as 1.64 to<br />

6.55 mg/kg-day caused neither mortality nor clinical signs <strong>of</strong> toxicity. A dose <strong>of</strong> 6.55 mg/kg-day<br />

resulted in blood Pb levels <strong>of</strong> 1.58 µg/mL. There were minimal changes in immune function<br />

(Redig et al., 1991).<br />

Repeated oral administration <strong>of</strong> Pb resulted in biochemical alterations in broiler chickens<br />

(Brar et al., 1997a,b). At a dose <strong>of</strong> 200 mg/kg-day Pb-acetate, there were significant increases in<br />

AX7-47


plasma levels <strong>of</strong> uric acid and creatinine and significant declines in the levels <strong>of</strong> total proteins,<br />

albumin, glucose, and cholesterol. Brar et al. (1997a) suggested that increased uric acid and<br />

creatinine levels could be due to an accelerated rate <strong>of</strong> protein catabolism and/or kidney damage.<br />

They also suggested that the decline in plasma proteins and albumin levels may be caused by<br />

diarrhea and liver dysfunction due to the Pb exposure. Brar et al. (1997b) also found that<br />

significant changes in plasma enzymes may be causing damage to other organs.<br />

<strong>Lead</strong> can cause an increase in tissue lipid peroxides and changes in glutathione<br />

concentrations, which may be related to peroxidative damage <strong>of</strong> cell membranes (Mateo and<br />

H<strong>of</strong>fman, 2001). There are species-specific differences in resistance to oxidative stress (lipid<br />

peroxidation), which may explain why Canada geese are more sensitive to Pb poisoning than<br />

mallards (Mateo and H<strong>of</strong>fman, 2001). <strong>Lead</strong> also caused an increase in the production <strong>of</strong> the fatty<br />

acid arachidonic acid, which has been associated with changes in bone <strong>for</strong>mation and immune<br />

response (Mateo et al., 2003a). The effects observed by Mateo et al. (2003a,b) were associated<br />

with very high concentrations <strong>of</strong> Pb in the diet (1840 mg Pb/kg diet), much higher than would be<br />

found generally in the environment, and high enough that birds decreased their food intake.<br />

<strong>Lead</strong> also induces lipid peroxidation in plants. Rice plants exposed to a highly toxic level<br />

<strong>of</strong> Pb (1000 µM in nutrient solution) showed elevated levels <strong>of</strong> lipid peroxides, increased activity<br />

<strong>of</strong> superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, and glutatione reductase<br />

(Verma and Dubey, 2003). The elevated levels <strong>of</strong> these enzymes suggest the plants may have an<br />

antioxidative defense mechanism against oxidative injury caused by Pb (Verma and Dubey,<br />

2003).<br />

AX7.1.2.6 Factors that Modify Organism Response<br />

Research has demonstrated that Pb may affect survival, reproduction, growth,<br />

metabolism, and development in a wide range <strong>of</strong> species. These effects may be modified by<br />

chemical, biological, and physical factors. The factors that modify responses <strong>of</strong> organisms to Pb<br />

are described in the following sections.<br />

Genetics<br />

Uptake and toxicity <strong>of</strong> Pb to plants are influenced strongly by the type <strong>of</strong> plant. Liu et al.<br />

(2003) found that Pb uptake and translocation by rice plants differed by cultivar (a cultivated<br />

AX7-48


variety <strong>of</strong> plant produced by selective breeding) but was not related to genotype. Twenty<br />

cultivars were tested from three genotypes. The differences in Pb concentrations among<br />

cultivars were smallest when comparing concentrations in the grains at the ripening stage.<br />

This study also found that toxicity varied by cultivar; at 800 mg Pb/kg soil, some cultivars<br />

were greatly inhibited, some were significantly improved, and others showed no change.<br />

Dearth et al. (2004) compared the response <strong>of</strong> Fisher 344 (F344) rats and Sprague-Dawley<br />

(SD) rats to exposure via gavage to 12 mg Pb/mL as Pb-acetate. Blood Pb levels in the F344<br />

dams were higher than those <strong>of</strong> the SD dams. <strong>Lead</strong> delayed the timing <strong>of</strong> puberty and<br />

suppressed hormone levels in F344 <strong>of</strong>fspring. These effects were not observed in the <strong>of</strong>fspring<br />

<strong>of</strong> SD rats, even when the dose was doubled. The authors conclude that F344 rats are more<br />

sensitive to Pb (Dearth et al., 2004).<br />

Biological Factors<br />

Several biological factors may influence Pb uptake and organism response, including<br />

organism age, sex, species, feeding guild, and, <strong>for</strong> plants, the presence <strong>of</strong> mycorrhizal fungi.<br />

Monogastric animals are more sensitive to Pb than ruminants (Humphreys, 1991).<br />

Younger organisms may be more susceptible to Pb toxicity (Eisler, 1988; Humphreys,<br />

1991). Nestlings are more sensitive to the effects <strong>of</strong> Pb than older birds, and young altricial birds<br />

(species unable to self-regulate body heat at birth, such as songbirds), are considered more<br />

sensitive than precocial birds (species that have a high degree <strong>of</strong> independence at birth, such as<br />

quail, ducks, and poultry) (Scheuhammer, 1991).<br />

Gender can also have an effect on the accumulation <strong>of</strong> Pb by wildlife (Eisler, 1988).<br />

Female birds accumulate more Pb than males (Scheuhammer, 1987; Tejedor and Gonzalez,<br />

1992). These and other authors have related this to the increased requirement <strong>for</strong> calcium in<br />

laying females.<br />

Different types <strong>of</strong> invertebrates accumulate different amounts <strong>of</strong> Pb from the environment<br />

(U.S. Environmental Protection Agency, 1986a). There may be species- and sex-specific<br />

differences in accumulation <strong>of</strong> Pb into invertebrates, specifically arthropods. This has been<br />

shown by Wilczek et al. (2004) who studied two species <strong>of</strong> spider, the web-building<br />

A. labyrinthica and the active hunter wolf spider P. lugubris. The body burdens <strong>of</strong> Pb in the<br />

wolf spider were higher than in the web-building spider, and this may be due to the more<br />

AX7-49


effective use <strong>of</strong> glutathione metabolism pathways in A. labyrinthica. Body burdens <strong>of</strong> females<br />

were lower than those <strong>of</strong> males in both species. This was also observed in spiders by Rabitsch<br />

(1995a). Females are thought to be able to detoxify and excrete excess metals more effectively<br />

than males (Wilczek et al., 2004). <strong>Lead</strong> accumulation has been measured in numerous species <strong>of</strong><br />

arthropods with different feeding strategies. Differences were observed between species<br />

(Janssen and Hogervorst, 1993; Rabitsch, 1995a) and depending upon sex (Rabitsch, 1995a),<br />

developmental stage (Gintenreiter et al., 1993; Rabitsch, 1995a), and season (Rabitsch, 1995a).<br />

Uptake <strong>of</strong> Pb may be enhanced by symbiotic associations between plant roots and<br />

mycorrhizal fungi. Similar to the mechanism associated with increased uptake <strong>of</strong> nutrients,<br />

mycorrhizal fungi also may cause an increase in the uptake <strong>of</strong> Pb by increasing the surface area<br />

<strong>of</strong> the roots, the ability <strong>of</strong> the root to absorb particular ions, and the transfer <strong>of</strong> ions through the<br />

soil (U.S. Environmental Protection Agency, 1986a). There have been contradictory results<br />

published in the literature regarding the influence <strong>of</strong> mycorrhizal organisms on the uptake and<br />

toxicity <strong>of</strong> Pb to plants (see review in Påhlsson, 1989). Lin et al. (2004) found that the<br />

bioavailability <strong>of</strong> Pb increased in the rhizosphere <strong>of</strong> rice plants, although the availability varied<br />

with Pb concentration in soil. Bioavailability was measured as the soluble plus exchangeable Pb<br />

fraction from sequential extraction analysis. The authors hypothesized that the enhanced<br />

solubility <strong>of</strong> Pb may be due to a reduced pH in the rhizosphere or, more likely, the greater<br />

availability <strong>of</strong> organic ligands, which further stimulates microbial growth (Lin et al., 2004).<br />

Increased bioavailability <strong>of</strong> Pb in soil may increase the uptake <strong>of</strong> Pb into plants, although<br />

this was not assessed by Lin et al. (2004). However, Dixon (1988) found that red oak<br />

(Quercus rubra) seedlings with abundant ectomycorrhizae had lower Pb concentrations in their<br />

roots than those seedlings without this fungus, although only at the 100 mg Pb/kg sandy loam<br />

soil concentration (no differences were found at lower Pb concentrations). <strong>Lead</strong> in soil also was<br />

found to be toxic to the ectomycorrhizal fungi after 16 weeks <strong>of</strong> exposure to 50 mg Pb/kg or<br />

more (Dixon, 1988). Malcova and Gryndler (2003) showed that maize root exudates from<br />

mycorrhizal fungi can ameliorate heavy metal toxicity until a threshold metal concentration was<br />

surpassed. This may explain the conflicting results in the past regarding the uptake and toxicity<br />

<strong>of</strong> Pb to plants with mycorrhizal fungi.<br />

The type <strong>of</strong> food eaten is a major determinant <strong>of</strong> Pb body burdens in small mammals, with<br />

insectivorous animals accumulating more Pb than herbivores or granivores (U.S. Environmental<br />

AX7-50


Protection Agency, 1986a). In fact, the main issue identified by the <strong>EPA</strong> (U.S. Environmental<br />

Protection Agency, 1986a) related to invertebrate uptake <strong>of</strong> Pb was not toxicity to the<br />

invertebrates, but accumulation <strong>of</strong> Pb to levels that may be toxic to their consumers. Several<br />

authors suggest that shrews are a good indicator <strong>of</strong> metal contamination, because they tend to<br />

accumulate higher levels <strong>of</strong> metals than herbivorous small mammals (see data summary in<br />

Sample et al. (1998)). Shrews accumulate higher levels <strong>of</strong> metals in contaminated habitats,<br />

because their diet mainly consists <strong>of</strong> detritivores (i.e., earthworms) and other soil invertebrates in<br />

direct contact with the soil (Beyer et al., 1985).<br />

Physical/Environmental Factors<br />

Plants<br />

The uptake and distribution <strong>of</strong> Pb into higher plants from the soil is affected by various<br />

chemical and physical factors including the chemical <strong>for</strong>m <strong>of</strong> Pb, the presence <strong>of</strong> other metal<br />

ions, soil type, soil pH, cation exchange capacity (CEC), the amount <strong>of</strong> Fe/Mn-oxide films<br />

present, organic matter content, temperature, light, and nutrient availability. A small fraction <strong>of</strong><br />

Pb in soil may be released into the soil water, which is then available to be taken up by plants<br />

(U.S. Environmental Protection Agency, 1986a).<br />

The <strong>for</strong>m <strong>of</strong> Pb has an influence on its toxicity to plants. For example, Pb-oxide is less<br />

toxic than more bioavailable <strong>for</strong>ms such as Pb-chloride or Pb-acetate. In a study by Khan and<br />

Frankland (1983), radish plants were exposed to Pb-oxide and Pb-chloride in a loamy sand at pH<br />

5.4, in a 42-day study. In a tested concentration range <strong>of</strong> 0 to 5000 mg/kg, root growth was<br />

inhibited by 24% at 500 mg/kg <strong>for</strong> Pb-chloride and an EC50 <strong>of</strong> 2400 mg/kg was calculated from a<br />

dose-response curve. Plant growth ceased at 5000 mg/kg and shoots exhibited an EC50 <strong>of</strong><br />

2800 mg/kg. For Pb-oxide exposure (concentration range <strong>of</strong> 0 to 10,000 mg/kg), reported results<br />

indicate an EC50 <strong>of</strong> 12,000 mg/kg <strong>for</strong> shoot growth and an EC50 <strong>of</strong> 10,000 mg/kg <strong>for</strong> root growth.<br />

There was no effect on root growth at 500 mg/kg and a 26% reduction at 1000 mg/kg Pb oxide.<br />

Soil pH is the most influential soil property with respect to uptake and accumulation <strong>of</strong> Pb<br />

into plant species. This is most likely due to increased bioavailability <strong>of</strong> Pb created by low soil<br />

pH. At low soil pH conditions, markedly elevated Pb toxicity was reported <strong>for</strong> red spruce<br />

(P. rubens) (Seiler and Paganelli, 1987). At a soil pH <strong>of</strong> 4.5, ryegrass (Lolium hybridum)<br />

AX7-51


and oats (Avena sativa) had significantly higher Pb concentrations after 3 months <strong>of</strong> growth<br />

compared to plants grown at pH 6.4 (Allinson and Dzialo, 1981).<br />

Invertebrates<br />

The uptake <strong>of</strong> Pb into invertebrates depends on the physical environment and parameters<br />

such as pH, calcium concentration, organic matter content, and CEC. Greater accumulation is<br />

found generally when the soil pH or organic content is lower (U.S. Environmental Protection<br />

Agency, 1986a).<br />

Soil pH has a significant influence on uptake <strong>of</strong> Pb into invertebrates. Perämäki et al.<br />

(1992) studied the influence <strong>of</strong> soil pH on uptake into the earthworm Aporrectodea caliginosa.<br />

<strong>Lead</strong> accumulation was lowest at the highest pH values, but there was no statistical difference<br />

due to variability in the data. Variability in the response also was found by Bengtsson et al.<br />

(1986), who reared earthworms (Dendrobaena rubida) in acidified soils at pH 4.5, 5.5, or 6.5.<br />

<strong>Lead</strong> uptake into worms was pH-dependent, although the highest concentrations were not always<br />

found at the lowest pH. There was no clear relationship between Pb concentration in cocoons<br />

and soil pH, and Pb concentrations were higher in the hatchlings than in the cocoons. As has<br />

been reported in many other studies (Neuhauser et al., 1995), concentration factors (ratio <strong>of</strong> Pb in<br />

worm to Pb in soil) were lower at higher Pb concentrations in soil. The authors attribute some <strong>of</strong><br />

this to a lowered feeding activity in worms at higher Pb concentrations (Bengtsson et al., 1986).<br />

Beyer et al. (1987) and Morgan and Morgan (1988) recognized that other factors beyond<br />

soil pH could influence the uptake <strong>of</strong> Pb into earthworms, which may be the cause <strong>of</strong> the<br />

inconsistencies reported by several authors. Both studies evaluated worm uptake <strong>of</strong> Pb relative<br />

to pH, soil calcium concentration, and organic matter content. Morgan and Morgan (1988) also<br />

considered CEC, and Beyer et al. (1987) considered concentrations <strong>of</strong> phosphorus, potassium, or<br />

magnesium in soil. Both studies found that calcium concentrations in soil were correlated with<br />

soil pH. Morgan and Morgan (1988) also found that CEC was correlated with percentage<br />

organic matter. Soil pH (coupled with CEC) and soil calcium were found to play significant<br />

roles in the uptake <strong>of</strong> Pb into worms (Beyer et al., 1987; Morgan and Morgan, 1988). Beyer<br />

et al. (1987) noted that concentrations <strong>of</strong> phosphorus in soil had no effect.<br />

AX7-52


Nutritional Factors<br />

Diet is a significant modifier <strong>of</strong> Pb absorption and <strong>of</strong> toxic effects in many species <strong>of</strong><br />

birds and mammals (Eisler, 1988). Dietary deficiencies in calcium, zinc, iron, vitamin E, copper,<br />

thiamin, phosphorus, magnesium, fat, protein, minerals, and ascorbic acid increased Pb<br />

absorption and its toxic effects (Eisler, 1988).<br />

Mateo et al. (2003b) studied intraspecies sensitivity to Pb-induced oxidative stress, by<br />

varying the vitamin E content <strong>of</strong> mallard diets. Vitamin E can protect against peroxidative<br />

damage and was found to decrease the lipid peroxidation in nerves <strong>of</strong> birds; however, it did not<br />

alleviate any sign <strong>of</strong> the Pb poisoning. The authors hypothesize that inhibition <strong>of</strong> antioxidant<br />

enzymes and interaction with sulfhydryl groups <strong>of</strong> proteins may have a greater influence on Pb<br />

toxicity than lipid peroxidation (Mateo et al., 2003b). The effects observed by Mateo et al.<br />

(2003b) were associated with very high concentrations <strong>of</strong> Pb in diet (1840 mg Pb/kg diet), much<br />

higher than would be found generally in the environment, and high enough that the birds<br />

decreased their food intake.<br />

Mallard ducklings were exposed to Pb-contaminated sediment and either a low nutrition<br />

or optimal nutrition diet (Douglas-Stroebel et al., 2005). <strong>Lead</strong> exposure combined with a<br />

nutritionally inferior diet caused more changes in behavior (as measured by time bathing, resting,<br />

and feeding) than Pb exposure or low-nutrition diet alone. These effects may be due to the lownutrition<br />

diet being deficient in levels <strong>of</strong> protein, amino acids, calcium, zinc, and other nutrients.<br />

Zebra finches (Taeniopygia guttata) were exposed to Pb-acetate via drinking water at<br />

20 mg/L <strong>for</strong> 38 days, along with either a low- or high-calcium diet (Snoeijs et al., 2005). <strong>Lead</strong><br />

uptake into tissues was enhanced by a low-calcium diet. <strong>Lead</strong> did not affect body weight,<br />

hematocrit, or adrenal stress response. <strong>Lead</strong> suppressed the humoral immune response only in<br />

females on a low-calcium diet, suggesting increased susceptibility <strong>of</strong> females to Pb (Snoeijs<br />

et al., 2005).<br />

Interactions with Other Pollutants<br />

<strong>Lead</strong> can interact with other pollutants to exert toxicity in an antagonistic (less than<br />

additive), independent, additive, or synergistic (more than additive) manner. Concurrent<br />

exposure to Pb and additional pollutant(s) can affect the ability <strong>of</strong> plants to uptake Pb or the<br />

other pollutant. However, the uptake and toxic response <strong>of</strong> plants exposed to Pb combined with<br />

AX7-53


other metals is inconsistent (Påhlsson, 1989). There<strong>for</strong>e, no generalizations can be made about<br />

the relative toxicity <strong>of</strong> metal mixtures. For example, An et al. (2004) conducted acute, 5-day<br />

bioassays on cucumber exposed to Pb, Pb + copper, Pb + cadmium, or Pb + copper + cadmium<br />

in a sandy loam soil <strong>of</strong> pH 4.3. Shoot and root growth were measured. Depending on the tissue<br />

and metal combination, additivity, synergism, or antagonism was observed in the responses to<br />

these metals. In fact, the response in roots was not consistent with the response in shoots <strong>for</strong> the<br />

binary mixtures. However, the combined effects were greater in the roots than the shoots, which<br />

may be explained by the tendency <strong>for</strong> Pb and other heavy metals to be retained in the roots <strong>of</strong><br />

plants. In addition, the pattern <strong>of</strong> metal bioaccumulation into plant tissue did not always<br />

correlate with the toxic response. However, antagonism was observed in the response <strong>of</strong> roots<br />

and shoots exposed to all three metals, and this was reflected in the decreased accumulation <strong>of</strong><br />

metals into plant tissues. The authors hypothesized that this may be due to the <strong>for</strong>mation <strong>of</strong> less<br />

bioavailable metal complexes (An et al., 2004).<br />

He et al. (2004) found that selenium and zinc both inhibited the uptake <strong>of</strong> Pb into Chinese<br />

cabbage (Brassica rapa) and lettuce (Lactuca sativa). Zinc applied at 100 mg/kg or selenium<br />

applied at 1 mg/kg decreased the uptake <strong>of</strong> Pb (present in soil at 10 mg/kg as Pb-nitrate) into<br />

lettuce by 15% and 20%, respectively, and into Chinese cabbage by 23 and 20%, respectively.<br />

Selenium compounds were evaluated to determine whether they could change the<br />

inhibition <strong>of</strong> ALAD in liver, kidney, or brain <strong>of</strong> mice exposed to Pb-acetate (Perottoni et al.,<br />

2005). Selenium did not affect the inhibition <strong>of</strong> ALAD in the kidney or liver, but it did reverse<br />

the ALAD inhibition in mouse brain.<br />

Co-occurrence <strong>of</strong> cadmium with Pb resulted in reduced blood Pb concentrations in rats<br />

(Garcia and Corredor, 2004). The authors hypothesized that cadmium may block or antagonize<br />

the intestinal absorption <strong>of</strong> Pb, or the metallothionein induced by cadmium may sequester Pb.<br />

However, this was not observed in pigs, where blood Pb concentrations were greater when<br />

cadmium was also administered (Phillips et al., 2003). The effect on growth rate also was<br />

additive when both metals were given to young pigs (Phillips et al., 2003).<br />

AX7-54


AX7.1.2.7 Summary<br />

The current document expands upon and updates knowledge related to the uptake,<br />

detoxification, physiological effects, and modifying factors <strong>of</strong> Pb toxicity to terrestrial<br />

organisms.<br />

Surface Deposition onto Plants<br />

Recent work (Dalenberg and Van Driel, 1990; Jones and Johnston, 1991; Angelova et al.,<br />

2004) has supported previous results and conclusions that surface deposition <strong>of</strong> Pb onto aboveground<br />

vegetation from airborne sources may be significant (U.S. Environmental Protection<br />

Agency, 1986a). Similarly, it has been well documented previously that Pb in soil also is taken<br />

up by plants, although most remains in the roots, there is little translocation to shoots, leaves, or<br />

other plant parts (U.S. Environmental Protection Agency, 1986a). More recent work continues<br />

to support this finding (Sieghardt, 1990), and one study found increased tolerance in species with<br />

bulbs, possibly due to the storage <strong>of</strong> Pb in the bulb (Wierzbicka, 1999).<br />

Uptake Mechanism into Plants<br />

<strong>Lead</strong> was thought previously to be taken up by plants via the symplastic route (through<br />

cell membranes), although it was unknown whether some Pb also may be taken up via the<br />

apoplastic route (between cells) (U.S. Environmental Protection Agency, 1986a). Recent work<br />

has shown that the apoplastic route <strong>of</strong> transport is stopped in the primary roots by the endodermis<br />

(Sieghardt, 1990), supporting the previous conclusion that the symplastic route is the most<br />

significant route <strong>of</strong> transport into plant cells.<br />

Species Differences in Uptake into Earthworms<br />

Different species <strong>of</strong> earthworm accumulated different amounts <strong>of</strong> Pb, and this was not<br />

related to feeding strategy (U.S. Environmental Protection Agency, 1986a). This is supported by<br />

recent work, which has shown Aporrectodea accumulated more than Lumbricus (Terhivuo et al.,<br />

1994; Pižl and Josens, 1995), although this is not consistently observed (Spurgeon and Hopkin,<br />

1996a).<br />

AX7-55


Speciation and Form <strong>of</strong> <strong>Lead</strong><br />

Recent work supports previous conclusions that the <strong>for</strong>m <strong>of</strong> metal tested, and its<br />

speciation in soil, influence uptake and toxicity to plants and invertebrates (U.S. Environmental<br />

Protection Agency, 1986a). The oxide <strong>for</strong>m is less toxic that the chloride or acetate <strong>for</strong>ms,<br />

which are less toxic than the nitrate <strong>for</strong>m <strong>of</strong> Pb (Khan and Frankland, 1983; Lock and Janssen,<br />

2002; Bongers et al., 2004). However, these results must be interpreted with caution, as the<br />

counterion (e.g., the nitrate ion) may be contributing to the observed toxicity (Bongers et al.,<br />

2004).<br />

Detoxification in Plants<br />

<strong>Lead</strong> may be deposited in root cell walls as a detoxification mechanism (U.S.<br />

Environmental Protection Agency, 1986a), and this may be influenced by calcium concentrations<br />

(Antosiewicz, 2005). Yang et al. (2000) suggested that the oxalate content in root and root<br />

exudates reduced the bioavailability <strong>of</strong> Pb in soil, and that this was an important tolerance<br />

mechanism. Other hypotheses put <strong>for</strong>ward recently include the presence <strong>of</strong> sulfur ligands<br />

(Sharma et al., 2004) and the sequestration <strong>of</strong> Pb in old leaves (Szarek-Lukaszewska et al., 2004)<br />

as detoxification mechanisms.<br />

Detoxification in Invertebrates<br />

<strong>Lead</strong> detoxification has not been studied extensively in invertebrates. Glutathione<br />

detoxification enzymes were measured in two species <strong>of</strong> spider (Wilczek et al., 2004). <strong>Lead</strong> may<br />

be stored in waste nodules in earthworms (Hopkin, 1989) or as pyromorphite in the nematode<br />

(Jackson et al., 2005).<br />

Physiological Effects<br />

The effects on heme synthesis (as measured by ALAD activity and protoporphyrin<br />

concentration, primarily) have been well-documented (U.S. Environmental Protection Agency,<br />

1986a) and continue to be studied (Schlick et al., 1983; Scheuhammer, 1989; Henny et al., 1991;<br />

Redig et al., 1991; Beyer et al., 2000; H<strong>of</strong>fman et al., 2000a,b). However, Henny et al. (1991)<br />

caution that changes in ALAD and other enzyme parameters are not always related to adverse<br />

effects, but simply indicate exposure. Other effects on plasma enzymes, which may damage<br />

AX7-56


other organs, have been reported (Brar et al., 1997a,b). <strong>Lead</strong> also may cause lipid peroxidation<br />

(Mateo and H<strong>of</strong>fman, 2001), which may be alleviated by vitamin E, although Pb poisoning may<br />

still result (Mateo et al., 2003b). Changes in fatty acid production have been reported, which<br />

may influence immune response and bone <strong>for</strong>mation (Mateo et al., 2003a).<br />

Response Modification<br />

Genetics, biological factors, physical/environmental factors, nutritional factors, and other<br />

pollutants can modify terrestrial organism response to Pb. Fisher 344 rats were found to be more<br />

sensitive to Pb than Sprague-Dawley rats (Dearth et al., 2004). Younger animals are more<br />

sensitive than older animals (Eisler, 1988; Scheuhammer, 1991), and females generally are more<br />

sensitive than males (Scheuhammer, 1987; Tejedor and Gonzalez, 1992; Snoeijs et al., 2005).<br />

Monogastric animals are more sensitive than ruminants (Humphreys, 1991). Insectivorous<br />

mammals may be more exposed to Pb than herbivores (Beyer et al., 1985; Sample et al., 1998),<br />

and higher tropic-level consumers may be less exposed than lower trophic-level organisms<br />

(Henny et al., 1991). Diets deficient in nutrients (including calcium) result in increased uptake<br />

<strong>of</strong> Pb (Snoeijs et al., 2005) and greater toxicity (Douglas-Stroebel et al., 2005) in birds, relative<br />

to diets containing adequate nutrient levels.<br />

Mycorrhizal fungi may ameliorate Pb toxicity until a threshold is surpassed (Malcova and<br />

Gryndler, 2003), which may explain why some studies show increased uptake into plants (Lin<br />

et al., 2004) while others show no difference or less uptake (Dixon, 1988). Uptake <strong>of</strong> Pb into<br />

plants and soil invertebrates increases with a decrease in soil pH. However, calcium content,<br />

organic matter content, and cation exchange capacity <strong>of</strong> soils also have had a significant<br />

influence on uptake <strong>of</strong> Pb into plants and invertebrates (Beyer et al., 1987; Morgan and Morgan,<br />

1988).<br />

Interactions <strong>of</strong> Pb with other metals are inconsistent, depending on the endpoint<br />

measured, the tissue analyzed, the animal species, and the metal combination (Phillips et al.,<br />

2003; An et al., 2004; He et al., 2004; Garcia and Corredor, 2004; Perottoni et al., 2005).<br />

AX7.1.3 Exposure-Response <strong>of</strong> Terrestrial Species<br />

Section AX7.1.3 summarized the most important factors related to uptake <strong>of</strong> Pb by<br />

terrestrial organisms, the physiological effects <strong>of</strong> Pb, and the factors that modify terrestrial<br />

AX7-57


organism responses to Pb. Section AX7.1.4 outlines and highlights the critical recent<br />

advancements in the understanding <strong>of</strong> the toxicity <strong>of</strong> Pb to terrestrial organisms. This section<br />

begins with a summary <strong>of</strong> the conclusions from the 1986 <strong>Lead</strong> AQCD (U.S. Environmental<br />

Protection Agency, 1986a) and then summarizes the more recent critical research conducted on<br />

effects <strong>of</strong> Pb on primary producers, consumers, and decomposers. All concentrations are<br />

expressed as mg Pb/kg soil dw, unless otherwise indicated.<br />

<strong>Lead</strong> exposure may adversely affect organisms at different levels <strong>of</strong> organization, i.e.,<br />

individual organisms, populations, communities, or ecosystems. Generally, however, there is<br />

insufficient in<strong>for</strong>mation available <strong>for</strong> single materials in controlled studies to permit evaluation<br />

<strong>of</strong> specific impacts on higher levels <strong>of</strong> organization (beyond the individual organism). Potential<br />

effects at the population level or higher are, <strong>of</strong> necessity, extrapolated from individual level<br />

studies. Available population, community, or ecosystem level studies are typically conducted at<br />

sites that have been contaminated or adversely affected by multiple stressors (several chemicals<br />

alone or combined with physical or biological stressors). There<strong>for</strong>e, the best documented links<br />

between lead and effects on the environment are with effects on individual organisms. Impacts<br />

on terrestrial ecosystems are discussed in Section 7.1.5 and Annex AX7.1.5.<br />

The summary <strong>of</strong> recent critical advancements in understanding toxicity relies heavily on<br />

the work completed by a multi-stakeholder group, consisting <strong>of</strong> federal, state, consulting,<br />

industry, and academic participants, led by the <strong>EPA</strong> to develop Ecological Soil Screening Levels<br />

(Eco-SSLs). Eco-SSLs describe the concentrations <strong>of</strong> contaminants in soils that would result in<br />

little or no measurable effect on ecological receptors (U.S. Environmental Protection Agency,<br />

2005a). They were developed by the U.S. <strong>EPA</strong> <strong>for</strong> use in screening-level assessments at<br />

Superfund sites to identify contaminants requiring further evaluation in an ecological risk<br />

assessment and were not designed to be used as cleanup target levels. The Eco-SSLs are<br />

intentionally conservative in order to provide confidence that contaminants, which could present<br />

an unacceptable risk, are not screened out early in the evaluation process. That is, at or below<br />

these levels, adverse effects are considered unlikely. Eco-SSLs were derived <strong>for</strong> terrestrial<br />

plants, soil invertebrates, birds, and mammals. Detailed procedures using an extensive list <strong>of</strong><br />

acceptability and exclusion criteria (U.S. Environmental Protection Agency, 2005a) were used in<br />

screening the toxicity studies to ensure that only those that met minimum quality standards were<br />

used to develop the Eco-SSLs. In addition, two peer reviews were completed during the<br />

AX7-58


Eco-SSL development process. The first was a consultation with the <strong>EPA</strong> Science Advisory<br />

Board (SAB) in April 1999, and the second was a peer review workshop in July 2000, which was<br />

open to the public.<br />

Several conservative factors were incorporated into the development <strong>of</strong> the Eco-SSLs.<br />

For the plant and invertebrate Eco-SSLs, studies were scored to favor relatively high<br />

bioavailability. For wildlife Eco-SSLs, only species with a clear exposure link to soil were<br />

considered (generalist species, species with a link to the aquatic environment, or species which<br />

consume aerial insects were excluded), simple diet classifications were used (100% plants, 100%<br />

earthworms or 100% animal prey) when in reality wildlife consume a varied diet, species were<br />

assumed to <strong>for</strong>age exclusively at the contaminated site, relative bioavailability or Pb in soil and<br />

diet was assumed to be 1, and the TRV was selected as the geometric mean <strong>of</strong> NOAELs unless<br />

this value was higher than the lowest bounded LOAEL <strong>for</strong> mortality, growth or reproduction<br />

(U.S. Environmental Protection Agency, 2005a,b).<br />

Areas <strong>of</strong> research that were not addressed are effects from irrelevant exposure conditions<br />

relative to airborne emissions <strong>of</strong> Pb (e.g., Pb shot, Pb paint, injection studies, studies conducted<br />

on mine tailings, and studies conducted with hydroponic solutions); mixture toxicity (addressed<br />

in Section AX7.1.3); issues related to indirect effects (e.g., effects on predator/prey interactions,<br />

habitat alteration, etc.); and human health-related research (e.g., hypertension), which is<br />

addressed in other sections <strong>of</strong> this document.<br />

The toxicity data presented herein should be reviewed with a note <strong>of</strong> caution regarding<br />

their relevance to field conditions. Laboratory studies, particularly those using Pb-spiked soil,<br />

generally do not allow the soil to equilibrate following the addition <strong>of</strong> Pb and prior to the<br />

addition <strong>of</strong> test organisms. This may result in increased bioavailability and overestimation <strong>of</strong> Pb<br />

toxicity relative to actual environmental conditions (Davies et al., 2003).<br />

AX7.1.3.1 Summary <strong>of</strong> Conclusions from the 1986 <strong>Lead</strong> <strong>Criteria</strong> Document<br />

The 1996 <strong>Lead</strong> AQCD, <strong>Volume</strong> <strong>II</strong> (U.S. Environmental Protection Agency, 1986a)<br />

reviewed the literature on the toxicity <strong>of</strong> Pb to plants, soil organisms, birds, and mammals.<br />

The main conclusions from that document are provided below.<br />

AX7-59


Primary Producers<br />

Commonly reported effects <strong>of</strong> Pb on vascular plants include the inhibition <strong>of</strong><br />

photosynthesis, respiration, and/or cell elongation, all <strong>of</strong> which reduce plant growth. However, it<br />

was noted that studies <strong>of</strong> other effects on plant processes such as maintenance, flowering, and<br />

hormone development had not been conducted; there<strong>for</strong>e, no conclusion could be reached<br />

concerning effects <strong>of</strong> Pb on these processes.<br />

The <strong>EPA</strong> (U.S. Environmental Protection Agency, 1986a) concluded that most plants<br />

experience reduced growth when Pb concentrations in soil moisture (the film <strong>of</strong> moisture<br />

surrounding soil particles in the root zone <strong>of</strong> soil) exceed 2 to 10 mg/kg. It also was concluded<br />

that most plants would experience reduced growth (inhibition <strong>of</strong> photosynthesis, respiration, or<br />

cell elongation) in soils <strong>of</strong> ∃10,000 mg/kg when soil composition and pH are such that<br />

bioavailability <strong>of</strong> Pb in the soil is low (see Section AX7.1.3 <strong>for</strong> details on factors affecting<br />

bioavailability <strong>of</strong> Pb in soil). Acid soils or soils with low organic matter tend to increase Pb<br />

bioavailability and would inhibit plants at much lower Pb concentrations (e.g., as low as<br />


Decomposers<br />

Lack <strong>of</strong> decomposition has been observed as a particular problem around smelter sites.<br />

<strong>Lead</strong> concentrations between 10,000 and 40,000 mg/kg soil can eliminate populations <strong>of</strong><br />

decomposer bacteria and fungi (U.S. Environmental Protection Agency, 1986a). <strong>Lead</strong> may<br />

affect decomposition processes by direct toxicity to specific groups <strong>of</strong> decomposers, by<br />

deactivating enzymes excreted by decomposers to break down organic matter, or by binding with<br />

the organic matter and rendering it resistant to the action <strong>of</strong> decomposers.<br />

Microorganisms are more sensitive than plants to Pb in soil. Delayed decomposition may<br />

occur at between 750 and 7500 mg/kg soil (depending on soil type and other conditions).<br />

Nitrification is inhibited by 14% at 1000 mg/kg soil.<br />

U.S. Environmental Protection Agency Staff Review <strong>of</strong> 1986 <strong>Criteria</strong> Document<br />

The <strong>EPA</strong> reviewed the 1986 <strong>Lead</strong> AQCD and presented an overall summary <strong>of</strong><br />

conclusions and recommendations (U.S. Environmental Protection Agency, 1990). The major<br />

conclusion was that available laboratory and field data indicated that high concentrations <strong>of</strong> Pb<br />

can affect certain plants and alter the composition <strong>of</strong> soil microbial communities. It was noted<br />

that few field studies were available in which Pb exposures and associated effects in wildlife<br />

were reported.<br />

AX7.1.3.2 Recent Studies on the Effects <strong>of</strong> <strong>Lead</strong> on Primary Producers<br />

Several studies published since 1986 have reported terrestrial plant exposure to Pb in soil,<br />

many <strong>of</strong> which were reviewed during the development <strong>of</strong> the Eco-SSLs (U.S. Environmental<br />

Protection Agency, 2005b). The relevant in<strong>for</strong>mation from the Eco-SSL document (U.S.<br />

Environmental Protection Agency, 2005b) is summarized below. A literature search and review<br />

also was conducted to identify critical papers published since 2002, which is when the literature<br />

search was completed <strong>for</strong> Eco-SSL development, and no new papers were identified as critical to<br />

the understanding <strong>of</strong> Pb toxicity to terrestrial primary producers.<br />

Effects observed in studies conducted since the 1986 <strong>Lead</strong> AQCD are similar to those<br />

reported previously and include decreased photosynthetic and transpiration rates and decreased<br />

growth and yield (U.S. Environmental Protection Agency, 2005b). The phytotoxicity <strong>of</strong> Pb is<br />

considered relatively low, due to the limited availability and uptake <strong>of</strong> Pb from soil and soil<br />

AX7-61


solution and minimal translocation <strong>of</strong> Pb from roots to shoots (Påhlsson, 1989). Although many<br />

laboratory toxicity studies have reported effects on plants, there are few reports <strong>of</strong> phytotoxicity<br />

from Pb exposure under field conditions. For example, Leita et al. (1989) and Sieghardt (1990)<br />

reported high concentrations <strong>of</strong> Pb and other metals in soil and vegetation collected around<br />

mining areas in Europe, with no toxicity symptoms observed in plants or fruit.<br />

The literature search completed <strong>for</strong> the terrestrial plant Eco-SSL development identified<br />

439 papers <strong>for</strong> detailed review, <strong>of</strong> which 28 met the minimum criteria (U.S. Environmental<br />

Protection Agency, 2005a). Thirty ecotoxicological endpoints were gleaned from these 28<br />

papers and were further evaluated; most <strong>of</strong> those evaluated growth (biomass), which was<br />

considered the most sensitive and ecologically relevant endpoint (U.S. Environmental Protection<br />

Agency, 2005b). Five <strong>of</strong> the endpoints, representing four species tested under three different<br />

combinations <strong>of</strong> pH and organic matter content, were used to develop the Eco-SSL <strong>of</strong> 120 mg/kg<br />

(115 mg/kg rounded to two significant digits) (Table AX7-1.3.1).<br />

Table AX7-1.3.1. Plant Toxicity Data Used to Develop the Eco-SSL<br />

Plant Species Soil pH<br />

AX7-62<br />

% Organic<br />

Matter<br />

Toxicity<br />

Parameter<br />

Pb in Soil<br />

(mg/kg dw)<br />

Loblolly pine (Pinus taeda) 4 2.5 MATC * (growth) 144<br />

Red maple (Acer rubrum) 4 2.5 MATC (growth) 144<br />

Berseem clover<br />

(Trifolium alexandrium)<br />

6.3 0.94 MATC (growth) 316<br />

Berseem clover 6.7 3.11 MATC (growth) 141<br />

Rye grass (Lolium rigidum) 5.6 0.1 MATC (growth) 22<br />

Geometric Mean 115<br />

*MATC = Maximum Acceptable Threshold Concentration, or the geometric mean <strong>of</strong> the NOAEC<br />

(no-observed-adverse-effect concentration) and LOAEC (lowest-observed-adverse-effect concentration).<br />

Source: U.S. Environmental Protection Agency (2005b).<br />

The 25 ecotoxicological endpoints that were not used to develop the Eco-SSL <strong>for</strong> plants<br />

are presented in Table AX7-1.3.2. The first six endpoints were considered eligible <strong>for</strong> Eco-SSL<br />

derivation but were not used; the remainder did not meet all <strong>of</strong> the requirements to be considered<br />

<strong>for</strong> inclusion in the Eco-SSL derivation process.


Table AX7-1.3.2. Plant Toxicity Data Not Used to Develop the Eco-SSL<br />

Plant Species Soil pH<br />

Studies eligible <strong>for</strong> Eco-SSL derivation, but not used<br />

Berseem clover<br />

(Trifolium alexandrium)<br />

Tomato<br />

(Lycopericon esculentum)<br />

AX7-63<br />

% Organic<br />

Matter Toxicity Parameter<br />

Pb in Soil<br />

(mg/kg dw)<br />

6.7 3.11 MATC 141<br />

7.73 1.70 MATC 71<br />

Tomato 8.20 0.86 MATC 71<br />

Fenugreek<br />

(Trigonella foenum-graecum)<br />

8.3 0.5 MATC 283<br />

Spinach (Spinacea oleracea) 6.7 3.0 MATC 424<br />

Corn (Zea mays) 6.5 2.1 MATC 158<br />

Sow thistle (Sonchus oleraceus) 7.23 1.6 MATC 2,263<br />

Studies not eligible <strong>for</strong> Eco-SSL derivation<br />

Loblolly pine (Pinus taeda) 5.5 3.4 NOAEC 480<br />

Red oak (Quercus rubra) 6 1.5 LOAEC 100<br />

Spinach 6.7 0.0 NOAEC 600<br />

Alfalfa (Medicago sativa) 6.4 1.0 NOAEC 250<br />

Alfalfa 6.9 1.7 NOAEC 250<br />

Alfalfa 6.9 1.7 NOAEC 250<br />

Radish (Raphanus sativus) 6.9 1.0 LOAEC 500<br />

Radish 6.9 1.0 LOAEC 100<br />

Radish 6.9 1.0 LOAEC 100<br />

Onion (Allium cepa) 8.3 0.5 LOAEC 50<br />

Radish 5.1 8.0 NOAEC 600<br />

Carrot (Daucus carota) 7.0 0.6 NOAEC 85<br />

Peas (Pisum sativum) 7.0 0.6 NOAEC 85<br />

Barley (Hordeum vulgare) 6.0 2.5 NOAEC 1,000<br />

Alfalfa 6.9 4.8 NOAEC 250<br />

Tomato 7.45 2.06 MATC 35<br />

Spinach 6.7 8.0 NOAEC 600<br />

Radish 6.2 8.0 NOAEC 600<br />

Radish 7.1 8.0 NOAEC 600<br />

*MATC = Maximum Acceptable Threshold Concentration, or the geometric mean <strong>of</strong> the NOAEC<br />

(no-observed-adverse-effect concentration) and LOAEC (lowest-observed-adverse-effect concentration).<br />

Source: U.S. Environmental Protection Agency (2005b).


AX7.1.3.3 Recent Studies on the Effects <strong>of</strong> <strong>Lead</strong> on Consumers<br />

Since the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a), there have<br />

been several studies in which birds and mammals were exposed to Pb via ingestion (primarily<br />

through dietary Pb). Many <strong>of</strong> these were reviewed during development <strong>of</strong> the Eco-SSLs (U.S.<br />

Environmental Protection Agency, 2005b). The relevant in<strong>for</strong>mation from the Eco-SSL<br />

document (U.S. Environmental Protection Agency, 2005b) is described below. A literature<br />

search and review was conducted to identify critical papers published since 2002. These recent<br />

critical papers are described briefly below. No studies were found that used inhalation exposures<br />

to evaluate endpoints such as survival, growth, and reproduction in birds or mammals. All<br />

studies described below exposed organisms via ingestion (drinking water or diet) or gavage.<br />

The Eco-SSLs <strong>for</strong> avian and mammalian consumers are presented as Pb concentrations in<br />

soil. These concentrations were calculated by assuming exposure to Pb via incidental soil<br />

ingestion and ingestion <strong>of</strong> Pb-contaminated food, and using a NOAEL as the TRV (U.S.<br />

Environmental Protection Agency, 2005a). A simplified version <strong>of</strong> the equation used to<br />

calculate the Eco-SSL is:<br />

HQ=<br />

[ ( C soil × IRsoil)<br />

+ ( Cfood×<br />

IRfood)<br />

]<br />

AX7-64<br />

TRV<br />

where:<br />

HQ = hazard quotient (1 mg Pb/kg bw/day)<br />

Csoil = concentration <strong>of</strong> Pb in soil (mg Pb/kg soil)<br />

IRsoil = incidental soil ingestion rate (kg soil/day)<br />

Cfood = concentration <strong>of</strong> Pb in food (mg Pb/kg food)<br />

IRfood = food ingestion rate (kg food/day)<br />

BW = body weight (kg)<br />

TRV = toxicity reference value (mg Pb/kg bw/day)<br />

÷ BW<br />

Food ingestion was estimated by modeling the uptake <strong>of</strong> Pb from soil into each diet<br />

component (e.g., vegetation, invertebrates, etc.). Bioavailability <strong>of</strong> Pb in soil and food was<br />

assumed to be 100%. The Eco-SSL is equivalent to the concentration <strong>of</strong> Pb in soil that results in<br />

an HQ = 1. The two factors that may have the most significant influence on the resulting Eco-<br />

SSL are the assumption <strong>of</strong> 100% bioavailability <strong>of</strong> Pb in soil and diet and the selection <strong>of</strong> the<br />

(AX7-4)


TRV. The toxicity data that were reviewed to develop the TRV are presented in the following<br />

subsections.<br />

Representative avian and mammalian wildlife species were selected <strong>for</strong> modeling Pb<br />

exposures to wildlife with different diets and calculating the Eco-SSL. The avian species<br />

selected were dove (herbivore), woodcock (insectivore), and hawk (carnivore). The mammalian<br />

species selected were vole (herbivore), shrew (insectivore), and weasel (carnivore). The lowest<br />

<strong>of</strong> the three back-calculated soil concentrations, which resulted in an HQ = 1, was selected as the<br />

Eco-SSL. For Pb, the lowest values were <strong>for</strong> the insectivorous species <strong>of</strong> bird and mammal.<br />

Avian Consumers<br />

Effects on birds observed in studies conducted since the 1986 <strong>Lead</strong> AQCD (U.S.<br />

Environmental Protection Agency, 1986a) are similar to those reported previously: mortality,<br />

changes in juvenile growth rate and weight gain, effects on various reproductive measures, and<br />

changes in behavior (U.S. Environmental Protection Agency, 2005b). Reproductive effects<br />

following Pb exposure included declines in clutch size, number <strong>of</strong> young hatched, and number <strong>of</strong><br />

young fledged as well as decreased fertility or eggshell thickness. Few significant reproductive<br />

effects have been reported in birds at Pb concentrations below 100 mg/kg in the diet<br />

(Scheuhammer, 1987).<br />

The literature search completed <strong>for</strong> Eco-SSL development identified 2,429 papers <strong>for</strong><br />

detailed review <strong>for</strong> either avian or mammalian species, <strong>of</strong> which 54 met the minimum criteria <strong>for</strong><br />

further consideration <strong>for</strong> avian Eco-SSL development (U.S. Environmental Protection Agency,<br />

2005b). The 106 toxicological data points <strong>for</strong> birds that were further evaluated included<br />

biochemical, behavioral, physiological, pathological, reproductive, growth, and survival effects.<br />

Growth and reproduction data were used to derive the Eco-SSL (Table AX7-1.3.3;<br />

Figure AX7-1.3.1). The geometric mean <strong>of</strong> the NOAELs was calculated as 10.9 mg/kg-day,<br />

which was higher than the lowest bounded LOAEL (the term “bounded” means that both a<br />

NOAEL and LOAEL were obtained from the same study). There<strong>for</strong>e, the highest bounded<br />

NOAEL that was lower than the lowest bounded LOAEL <strong>for</strong> survival, growth, or reproduction<br />

(1.63 mg Pb/kg bw-day) was used as the TRV (U.S. Environmental Protection Agency, 2005b).<br />

The TRV was used to back-calculate the Eco-SSL <strong>of</strong> 11 mg/kg soil <strong>for</strong> avian species (U.S.<br />

AX7-65


AX7-66<br />

Avian<br />

Species<br />

Reproduction<br />

Japanese<br />

quail<br />

No. <strong>of</strong><br />

Doses<br />

Route <strong>of</strong><br />

Exposure<br />

Table AX7-1.3.3. Avian Toxicity Data Used to Develop the Eco-SSL<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

4 FD 5 w 6 w LB F REP PROG WO 0.194 1.94<br />

Chicken 3 FD 4 w NR NR LB F REP PROG WO 1.63 3.26<br />

Chicken 4 FD 30 d 22 w LB F EGG ALWT EG 2.69 4.04<br />

Mallard 2 FD 76 d NR NR SM F EGG ESTH EG 5.63<br />

American<br />

kestrel<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

3 FD 6 mo 1-6 yr AD F REP RSUC WO 12.0<br />

5 FD 5 w 6 d JV M REP TEWT TE 12.6 126<br />

5 FD 5 w 1 d JV M REP TEWT TE 67.4 135<br />

3 FD 32 d NR NR AD F REP PROG WO 125<br />

5 FD 12 w 0 d LB B REP EGPN EG 0.110<br />

4 FD 12 w NR NR LB F REP PROG WO 0.194<br />

Chicken 5 FD 10 w NR NR LB F REP PROG WO 3.26<br />

Ringed<br />

turtle dove<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

2 DR 11 w NR NR AD M REP TEWT TE 11.8<br />

2 FD 1 w 14 w JV F REP TPRD WO 93.1<br />

2 FD 27 d NR NR AD F REP PROG WO 377<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-67<br />

Avian<br />

Species<br />

Growth<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

No. <strong>of</strong><br />

Doses<br />

Route <strong>of</strong><br />

Exposure<br />

Table AX7-1.3.3 (cont’d). Avian Toxicity Data Used to Develop the Eco-SSL<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

3 FD 5 w 1 d JV F GRO BDWT WO 1.56 15.6<br />

3 FD 2 w 1 d JV B GRO BDWT WO 2.77<br />

2 FD 2 w 1 d JV NR GRO BDWT WO 4.64<br />

3 FD 4 w 0 d JV F GRO BDWT WO 5.93 59.3<br />

Chicken 4 FD 4 w 4 w JV NR GRO BDWT WO 6.14 61.4<br />

Chicken 4 FD 4 w 4 w JV NR GRO BDWT WO 7.10 71.0<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

Japanese<br />

quail<br />

5 FD 12 w 0 d JV F GRO BDWT WO 11.1 111<br />

5 FD 12 w 1 w JV F GRO BDWT WO 11.2 112<br />

5 FD 2 w 6 d JV NR GRO BDWT WO 12.6 126<br />

5 FD 1 w 1 d JV NR GRO BDWT WO 13.5 67.4<br />

Chicken 2 FD 21 d 1 d JV B GRO BDWT WO 14.2<br />

Duck 3 GV 3 mo 24 w MA F GRO BDWT WO 20.0<br />

American<br />

kestrel<br />

4 GV 10 d 1 d JV NR GRO BDWT WO 25.0 125<br />

Chicken 2 FD 20 d 1 d JV B GRO BDWT WO 28.4<br />

Japanese<br />

quail<br />

5 FD 14 d 1 d JV B GRO BDWT WO 34.5<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-68<br />

Avian<br />

Species<br />

American<br />

kestrel<br />

No. <strong>of</strong><br />

Doses<br />

Route <strong>of</strong><br />

Exposure<br />

Table AX7-1.3.3 (cont’d). Avian Toxicity Data Used to Develop the Eco-SSL<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

4 FD 60 d 1-2 yr AD B GRO BDWT WO 54.3<br />

Chicken 5 FD 2 w 1 d JV M GRO BDWT WO 61.3 123<br />

Mallard 4 FD 8 d 9 d JV NR GRO BDWT WO 66.9<br />

Chicken 5 FD 20 d 1 d JV M GRO BDWT WO 38.2<br />

Chicken 2 FD 3 w 1 d JV M GRO BDWT WO 53.1<br />

Japanese<br />

quail<br />

3 FD 32 d NR NR AD F GRO BDWT WO 64.3<br />

Chicken 2 FD 19 d 1 d JV M GRO BDWT WO 76.3<br />

Chicken 3 FD 2 w 1 d JV M GRO BDWT WO 124<br />

Chicken 4 FD 14 d 8 d JV M GRO BDWT WO 152<br />

Chicken 2 FD 20 d 1 d JV M GRO BDWT WO 163<br />

Chicken 2 OR 4 w NR NR JV B GRO BDWT WO 200<br />

Chicken 2 FD 7 d 1 d JV M GRO BDWT WO 262<br />

Chicken 2 FD 2 w 1 d JV M GRO BDWT WO 270<br />

Chicken 2 FD 7 d 1 d IM NR GRO BDWT WO 273<br />

Chicken 2 FD 14 d 8 d JV M GRO BDWT WO 282<br />

LOAEL<br />

(mg/kg<br />

bw/day)<br />

AD = adult; ALWT = albumin weight; B = both; BDWT = body weight changes; d = days; DR = drinking water; EG = egg; EGG = effects on eggs; EGPN = egg production; ESTH = eggshell<br />

thinning; F = female; FD = food; GRO = growth; GV = gavage; JV = juvenile; LB = laying bird; MA = mature; M = male; mo = months; NR = not reported; OR = other oral; PROG = progeny counts<br />

or numbers; REP = reproduction; RSUC = reproductive success; SM = sexually mature; TE = testes; TEWT = testes weight; TPRD = total production; w = weeks; WO = whole organism; yr = years.<br />

Source: U.S. Environmental Protection Agency (2005b)


Figure AX7-1.3.1. Avian reproduction and growth toxicity data considered in<br />

development <strong>of</strong> the Eco-SSL.<br />

Source: U.S. Environmental Protection Agency (2005b).<br />

Environmental Protection Agency, 2005b). For more in<strong>for</strong>mation on the rationale <strong>for</strong> selecting<br />

TRVs, please refer to U.S. Environmental Protection Agency (2003).<br />

Many <strong>of</strong> the toxicity data presented in the Eco-SSL document (U.S. Environmental<br />

Protection Agency, 2005b) are lower than those discussed in the 1986 <strong>Lead</strong> AQCD. The TRV<br />

and resulting Eco-SSL were derived using many conservative assumptions. For example, the<br />

<strong>EPA</strong> (U.S. Environmental Protection Agency, 2005b) recognizes that toxicity is observed over a<br />

wide range <strong>of</strong> doses (100 mg Pb/kg bw/day), even when considering only reproductive<br />

effects in the same species. In addition, the TRV <strong>of</strong> 1.63 mg/kg-day is lower than most <strong>of</strong> the<br />

reported doses that have been associated with measured effects. This is true <strong>for</strong> not only<br />

survival, growth, and reproductive effects but also biochemical, behavioral, physiological, and<br />

pathological effects, which generally are observed at lower concentrations than effects on growth<br />

or reproduction. In addition, the Eco-SSL was back-calculated using conservative modeling<br />

assumptions. There<strong>for</strong>e, the Eco-SSL <strong>of</strong> 11 mg/kg may be considered a conservative value.<br />

AX7-69


Very little research has been done to expand the knowledge <strong>of</strong> the toxicity <strong>of</strong> Pb to birds<br />

since the Eco-SSL work was done. However, several studies have been conducted on waterfowl.<br />

Toxicity data <strong>for</strong> waterfowl (in particular, mallards) were included in the soil Eco-SSL<br />

development process (Table AX7-1.3.3), although mallards may be more exposed to<br />

contaminants in sediment than soil. Effects on waterfowl may vary depending on the <strong>for</strong>m <strong>of</strong> Pb,<br />

characteristics <strong>of</strong> the sediment, the <strong>for</strong>aging strategy <strong>of</strong> the species (which may vary during<br />

reproduction), and the nutritional status <strong>of</strong> the animal. Sediment is recognized as an important<br />

route <strong>of</strong> exposure <strong>for</strong> waterfowl, particularly those species that dabble (i.e., <strong>for</strong>age on<br />

invertebrates in the sediment) (Beyer et al., 2000; Douglas-Stroebel et al., 2005). Douglas-<br />

Stroebel et al. (2005) found that mallard ducklings exposed to Pb-contaminated sediment and a<br />

low nutrition diet exhibited more changes in behavior (as measured by time bathing, resting, and<br />

feeding) than Pb exposure or low nutrition exposure alone. These effects may be due to the low<br />

nutrition diet being deficient in levels <strong>of</strong> protein, amino acids, calcium, zinc, and other nutrients.<br />

Beyer et al. (2000) related blood Pb to sublethal effects in waterfowl along the Coeur<br />

d=Alene River near a mining site in Idaho. The authors suggested that 0.20 mg/kg ww blood Pb<br />

represents the no-effect level. This no-effect blood concentration corresponds to a sediment Pb<br />

concentration <strong>of</strong> 24 mg/kg. A sediment concentration <strong>of</strong> 530 mg/kg, associated with a blood Pb<br />

concentration <strong>of</strong> 0.68 mg/kg ww, is suggested to be the lowest-effect concentration. These<br />

results are consistent with those <strong>of</strong> Scheuhammer (1989) who found blood Pb concentrations <strong>of</strong><br />

0.18 µg/mL to 0.65 µg/mL in mallards corresponded to conditions associated with greater than<br />

normal exposure to Pb, but that that should not be considered Pb poisoning. The study by Beyer<br />

et al. (2000) related blood Pb to waterfowl mortality and concluded that some swan mortality<br />

may occur at blood Pb levels <strong>of</strong> 1.9 mg/kg ww, corresponding to a sediment Pb concentration <strong>of</strong><br />

1800 mg/kg. Using the mean blood level <strong>of</strong> 3.6 mg/kg ww from all moribund swans in the<br />

study, it was predicted that half <strong>of</strong> the swans consuming sediment at the 90th percentile rate<br />

would die with chronic exposure to sediment concentrations <strong>of</strong> 3600 mg/kg.<br />

Mammalian Consumers<br />

Effects on mammals observed in studies conducted since the 1986 <strong>Lead</strong> AQCD (U.S.<br />

Environmental Protection Agency, 1986a) are similar to those reported previously: mortality,<br />

effects on reproduction, developmental effects, and changes in growth (U.S. Environmental<br />

AX7-70


Protection Agency, 2005b). Very little research has been done to expand the knowledge <strong>of</strong> the<br />

toxicity <strong>of</strong> Pb to mammalian wildlife, since the Eco-SSL work was done. Most studies<br />

conducted on mammals use laboratory animals to study potential adverse effects <strong>of</strong> concern <strong>for</strong><br />

humans, and such studies are summarized in other sections <strong>of</strong> this document.<br />

Of the 2,429 papers identified in the literature search <strong>for</strong> Eco-SSL development, 219 met<br />

the minimum criteria <strong>for</strong> further consideration <strong>for</strong> mammalian Eco-SSL development (U.S.<br />

Environmental Protection Agency, 2005b). The 343 ecotoxicological endpoints <strong>for</strong> mammals<br />

that were further evaluated included biochemical, behavioral, physiological, pathological,<br />

reproductive, growth, and survival effects. Growth and reproduction data were used to derive<br />

the Eco-SSL (Table AX7-1.3.4, Figure AX7-1.3.2). The geometric mean <strong>of</strong> the NOAELs was<br />

calculated as 40.7 mg/kg-day, which was higher than the lowest bounded LOAEL <strong>for</strong> survival,<br />

growth, or reproduction. There<strong>for</strong>e, the highest bounded NOAEL that was lower than the lowest<br />

bounded LOAEL <strong>for</strong> survival, growth, or reproduction (4.7 mg Pb/kg bw-day) was used as the<br />

TRV (U.S. Environmental Protection Agency, 2005b). The TRV was used to back-calculate the<br />

Eco-SSL <strong>of</strong> 56 mg/kg soil (U.S. Environmental Protection Agency, 2005b). For more<br />

in<strong>for</strong>mation on the rationale <strong>for</strong> selecting TRVs, please refer to U.S. Environmental Protection<br />

Agency (2003).<br />

A review <strong>of</strong> the data presented in the Eco-SSL document (U.S. Environmental Protection<br />

Agency, 2005b) reveals that effects on survival generally are observed at Pb doses much greater<br />

than those reported in the 1986 <strong>Lead</strong> AQCD, where it was concluded that most animals would<br />

die when consuming a regular dose <strong>of</strong> 2 to 8 mg Pb/kg bw-day (U.S. Environmental Protection<br />

Agency, 1986a). However, the data presented in the Eco-SSL document (U.S. Environmental<br />

Protection Agency, 2005b) generally do not support this. While five studies reported decreased<br />

survival at these levels, 34 other studies reported no mortality or a LOAEL <strong>for</strong> mortality at<br />

significantly higher doses (U.S. Environmental Protection Agency, 2005b). The five studies that<br />

supported this low toxic level were conducted on three species (mouse, rat, and cow) and used<br />

either gavage or drinking water as the exposure method. The 34 other studies included data on<br />

these three species as well as five other species (rabbit, dog, pig, hamster, and shrew) and<br />

included gavage and drinking water as well as food ingestion exposure methods. The NOAELs<br />

<strong>for</strong> survival ranged from 3.5 to 3200 mg/kg-day (U.S. Environmental Protection Agency,<br />

2005b). There<strong>for</strong>e, the review <strong>of</strong> data in the Eco-SSL document suggests effects on survival <strong>of</strong><br />

AX7-71


AX7-72<br />

Mammalian<br />

Species<br />

Reproduction<br />

No. <strong>of</strong><br />

Doses<br />

Route <strong>of</strong><br />

Exposure<br />

Table AX7-1.3.4. Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Rat 5 DR 62 d 21 d GE F REP PRWT WO 0.71 7.00<br />

Rat 6 DR 21 d NR NR GE F REP PRWT WO 1.00 5.00<br />

Rat 3 DR 35 d NR NR AD M REP RSUC WO 2.60 26.0<br />

Rat 4 DR 62 d 21 d GE B REP PRWT WO 3.00 6.0<br />

Sheep 3 FD 27 w NR NR GE F REP RSUC WO 4.50 —<br />

Rat 6 DR 21 d NR NR GE F REP PRWT WO 5.00 10.0<br />

Guinea pig 3 DR 40 d NR NR GE F REP PRWT WO 5.50 —<br />

Rat 5 FD 92 w 21 d JV M REP TEWT TE 7.50 74.9<br />

Rat 4 DR 23.8 d 21 d LC F REP Other WO 8.90<br />

Rat 5 DR 23.8 d 21 d GE F REP Other WO 9.10 45.0<br />

Cotton rat 3 DR 7 w NR NR AD M REP RHIS RT 12.4 170<br />

Rat 4 GV 9 w 10 w JV M REP SPCV TE 18.0 180<br />

Rat 3 DR 100 d 21 d GE F REP PRWT WO 25.4 —<br />

Rat 2 FD 35 d 70 d LC F REP PRWT WO 27.5 —<br />

Rat 4 DR 60 d NR NR SM M REP TEWT TE 31.6 63.2<br />

Rat 4 DR 56 d 70 d LC F REP PROG WO 32.5 —<br />

Rat 3 DR 31 d NR NR LC F REP PRWT WO 33.3 111<br />

Rat 4 GV 41 d NR NR GE F REP PRWT WO 41.0 54.6<br />

Rat 5 DR 1 w 94 d JV M REP SPCL SM 47.3 82.0<br />

Rat 4 DR 30 d NR NR SM M REP Other SV 56.0 285<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-73<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Hamster 2 DR 51 d 15 w GE F REP PROG WO 64.8 —<br />

Hamster 2 DR 14 d 11 w GE F REP PROG WO 64.9 —<br />

Rat 4 DR 37 d NR NR GE F REP PRWT WO 90.1 270<br />

Rat 5 GV 12 d NR NR GE F REP RSEM EM 100 150<br />

Rat 3 DR 68 d 25 d GE F REP PRWT WO 115 —<br />

Rat 4 DR 77 d 25 d GE F REP PRWT WO 116 —<br />

Rat 2 DR 21 d NR NR LC F REP PRWT WO 120 —<br />

Mouse 3 FD 8 w 2 mo GE M REP SPCV TE 144 1,440<br />

Mouse 7 FD 30 d NR NR LC F REP PRWT WO 202 506<br />

Mouse 7 FD 30 d NR NR LC F REP PRWT WO 202 506<br />

Rat 4 DR 21 d NR NR GE F REP DEYO WO 276 552<br />

Rat 5 DR 10 w NR NR AD M REP TEWT MT 294 587<br />

Rat 2 GV 102 d 30 d GE F REP PRWT WO 441 —<br />

Rat 2 DR 9 mo NR NR SM M REP RHIS TE 600 —<br />

Rat 4 FD 4 d NR NR LC F REP PRWT WO 601 1,500<br />

Rat 4 DR 13 w NR NR JV M REP FERT WO 639 —<br />

Mouse 4 GV 60 d NR NR AD F REP RPRD OV — 2.00<br />

Rat 3 FD 339 d 26-27 d JV B REP PRWT WO — 2.49<br />

Rat 2 DR 9 mo 21 d JV F REP DEYO WO — 2.94<br />

Mouse 2 DR 6 mo 21 d JV F REP DEYO WO — 3.62<br />

Mouse 4 GV 52 d 2 mo GE F REP PROG EM — 5.50<br />

Rat 2 DR 120 d 1 d GE M REP SPCL TE — 6.76<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-74<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Mouse 2 DR 5 w NR NR AD M REP TEDG TE — 16.6<br />

Mouse 2 GV 2 w NR NR JV M REP SPCL SM — 46.4<br />

Rat 2 FD 102 d NR NR GE F REP PROG WO — 49.6<br />

Rat 2 GV 3 mo 8 w SM M REP TEDG TE — 50.0<br />

Rat 2 DR 18 d NR NR GE F REP PRWT WO — 55.5<br />

Rat 3 DR 90 d NR NR AD M REP SPCL SM — 61.2<br />

Mouse 2 DR 23 d NR NR GE F REP PRWT WO — 78.6<br />

Mouse 2 DR 62 d NR NR GE F REP PRWT WO — 99.8<br />

Mouse 2 DR 18 w 6-8 w LC F REP PRWT WO — 137<br />

Mouse 2 DR 12 w 9 w SM M REP PRFM WO — 139<br />

Mouse 4 FD 18 d NR NR GE F REP PRWT WO — 154<br />

Rat 2 DR 4 w 99 d JV M REP SPCL SM — 171<br />

Rat 5 DR 6 w 4 mo GE F REP RHIS WO — 175<br />

Rat 2 DR 22 d NR NR GE F REP PRWT WO — 178<br />

Rat 3 DR 30 d 52 d JV M REP GREP PG — 198<br />

Rat 2 DR 13 w NR NR GE F REP PRWT WO — 200<br />

Rat 2 DR 21 d 80 d JV F REP PRWT WO — 218<br />

Rat 4 FD 3 w NR NR LC F REP PRWT WO — 221<br />

Rat 2 FD 1 w 19 w LC F REP PRWT WO — 222<br />

Rat 4 FD 3 w NR NR LC F REP PRWT WO — 230<br />

Rat 3 FD 25 d NR NR LC F REP PRWT WO — 258<br />

Rat 2 DR 21 d NR NR LC F REP PRWT WO — 330<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-75<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Rat 2 DR 30 d 52 d JV M REP SPCL SM — 354<br />

Rat 2 DR 17 d NR NR GE F REP PRWT WO — 360<br />

Rat 2 DR 24 d NR NR LC F REP PRWT WO — 360<br />

Rat 2 DR 12 d NR NR GE F REP PRWT WO — 362<br />

Rat 2 DR 30 d 27 d JV M REP SPCL SM — 364<br />

Mouse 2 DR 44 d NR NR GE F REP PRWT WO — 381<br />

Mouse 2 DR 14 d NR NR LC F REP PRWT WO — 381<br />

Rat 2 DR 50 d 24 d JV F REP RBEH WO — 381<br />

Mouse 2 DR 45 d 50-100 d GE F REP ODVP WO — 404<br />

Rat 2 DR 22 d NR NR GE F REP PRWT WO — 420<br />

Mouse 2 DR 48 d NR NR GE F REP PRWT WO — 437<br />

Rat 2 DR 9 mo 3 mo SM M REP SPCL TE — 579<br />

Rat 2 DR 9 mo NR NR SM M REP TEDG TE — 600<br />

Rat 2 DR 3 w 14 w LC F REP PRWT WO — 635<br />

Mouse 2 FD 7 d NR NR GE F REP RSUC EM — 646<br />

Rat 2 DR 126 d 1 d GE F REP PROG WO — 651<br />

Rat 2 DR 20 w 10 w GE F REP PRWT WO — 750<br />

Mouse 2 DR 4 d NR NR LC F REP PRWT WO — 762<br />

Rat 2 FD 2 w NR NR LC F REP PRWT WO — 828<br />

Rat 2 FD 7 d NR NR LC F REP PRWT WO — 833<br />

Rat 2 FD 21 d NR NR LC F REP PRWT WO — 991<br />

Mouse 4 DR 18 w 11 w JV F REP TEWT WO — 1,370<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-76<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Rat 2 FD 30 d NR NR LC F REP PRWT WO — 1,770<br />

Mouse 2 DR 14 w NR NR GE B REP PROG WO — 1,990<br />

Rat 2 FD 16 d NR NR LC F REP PROG WO — 2,570<br />

Rat 2 FD 7 d NR NR LC F REP PRWT WO — 2,570<br />

Rat 2 FD 25 d NR NR LC F REP PRWT WO — 2,570<br />

Rat M FD 27 d NR NR LC C REP PROG WO — 2,840<br />

Mouse 2 DR 14 w 21 d JV B REP PROG WO — 3,630<br />

Rat 2 FD 17 d NR NR LC F REP PRWT WO — 6,170<br />

Growth<br />

Horse 2 FD 15 w 20-21 w JV M GRO BDWT WO 0.15 —<br />

Rat 2 FD 21 d 0 d JV F GRO BDWT WO 0.5 —<br />

Rat 6 DR 21 d NR NR GE F GRO BDWT WO 1.00 5.00<br />

Rat 5 DR 7 d 50 d AD F GRO BDWT WO 1.27 13.0<br />

Cattle 4 OR 7 w 1 w JV M GRO BDWT WO 1.99 —<br />

Rat 3 DR 14 d 21 d JV F GRO BDWT WO 2.40 —<br />

Rat 2 DR 332 d 28 d JV B GRO BDWT WO 2.98 —<br />

Rat 4 DR 7 w 21 d GE F GRO BDWT WO 4.70 8.90<br />

Dog 3 FD 7 mo NR NR JV NR GRO BDWT WO 4.71 —<br />

Rat 3 DR 30 d 22-24 d JV M GRO BDWT WO 5.64 28.2<br />

Rat 4 DR 23 d 22 d JV F GRO BDWT WO 5.80 29.0<br />

Cattle 3 OR 84 d NR NR JV M GRO BDWT WO 7.79 —<br />

Rat 2 OR 6 w NR NR AD M GRO BDWT WO 9.10 —<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-77<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Rat 2 GV 8 w NR NR JV F GRO BDWT WO 10.0 —<br />

Rat 3 DR 6 mo NR NR AD M GRO BDWT WO 10.6 532<br />

Rabbit 3 GV 10 d 1 d JV F GRO BDWT WO 10.7 50.4<br />

Rat 2 DR 140 d 21 d JV M GRO BDWT WO 10.7 —<br />

Rat 2 DR 6 w NR NR JV M GRO BDWT WO 15.1 —<br />

Rat 2 FD 10 w NR NR JV M GRO BDWT WO 15.4 —<br />

Rat 2 OR 6 w NR NR AD M GRO BDWT WO 15.5 —<br />

Rat 2 DR 7 w NR NR JV M GRO BDWT WO 16.1 —<br />

Mouse 3 DR 14 d 0 d JV NR GRO BDWT WO 16.3 163<br />

Rat 4 GV 9 w 10 w JV M GRO BDWT WO 18.0 180<br />

Rat 3 FD 339 d 26-27 d JV B GRO BDWT WO 18.3 —<br />

Rat 4 GV 29 d NR NR SM F GRO BDWT WO 18.9 —<br />

Rat 7 DR 10 w NR NR JV M GRO BDWT WO 24.3 —<br />

Rat 4 DR 56 d 70 d LC F GRO BDWT WO 32.5 —<br />

Sheep 5 FD 84 d NR NR JV M GRO BDWT WO 32.7 —<br />

Rat 2 DR 10 w NR NR JV M GRO BDWT WO 38.5 —<br />

Cattle 4 FD 7 w 16 w JV M GRO BDWT WO 43.0 —<br />

Rat 2 GV 28 d 2 d JV B GRO BDWT WO 50.0 —<br />

Rat 5 DR 4 w 94 d JV M GRO BDWT WO 71.5 178<br />

Rat 4 GV 12 d 2 d JV B GRO BDWT WO 75.0 225<br />

Rat 2 FD 4 w NR NR JV M GRO BDWT WO 100 —<br />

Rat 6 DR 10 w NR NR JV M GRO BDWT WO 120 383<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-78<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Mouse 3 FD 4 w 3 mo JV B GRO BDWT WO 136 1360<br />

Mouse 2 DR 18 w 6-8 w LC F GRO BDWT WO 137 —<br />

Mouse 2 DR 12 w NR NR GE M GRO BDWT WO 139 —<br />

Rat 3 DR 30 d 52 d JV M GRO BDWT WO 169 508<br />

Rat 2 DR 4 w 99 d JV B GRO BDWT WO 171 —<br />

Rat 4 GV 18 d 3 d JV M GRO BDWT WO 180 —<br />

Mouse 3 DR 6 w 7 w SM M GRO BDWT WO 187 373<br />

Rat 4 GV 18 d 2 d JV B GRO BDWT WO 200 —<br />

Rat 2 GV 91 d NR NR JV M GRO BDWT WO 200 —<br />

Rat 2 DR 21 d 80 d JV F GRO BDWT WO 218 —<br />

Rat 4 FD 1 w NR NR LC F GRO BDWT WO 230 460<br />

Rat 4 DR 30 d NR NR JV M GRO BDWT WO 285 —<br />

Mouse 5 DR 10 w NR NR JV M GRO BDWT WO 362 —<br />

Rat 2 DR 30 d 52 d JV M GRO BDWT WO 364 —<br />

Rat 4 GV 14 d 14 d JV NR GRO BDWT WO 400 800<br />

Rat 5 GV 14 d 20 d JV NR GRO BDWT WO 400 800<br />

Rat 2 FD 14 mo 0 d JV NR GRO BDWT WO 431 —<br />

Rat 2 GV 102 d 30 d LC F GRO BDWT WO 441 —<br />

Mouse 4 GV 12 d 6 d JV M GRO BDWT WO 534 —<br />

Mouse 7 FD 30 d NR NR LC F GRO BDWT WO 632 1264<br />

Rat 2 DR 126 d 1 d GE F GRO BDWT WO 651 —<br />

Rat 2 DR 20 w 10 w GE F GRO BDWT WO 750 —<br />

LOAEL<br />

(mg/kg<br />

bw/day)


AX7-79<br />

Mammalian<br />

Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effect<br />

Type<br />

Effect<br />

Measure<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Mouse 7 FD 28 d NR NR LC F GRO BDWT WO 1260 2530<br />

Rat 4 FD 18 d NR NR LC F GRO BDWT WO 1500<br />

Rat 2 DR 9 d 21 d JV M GRO BDWT WO — 3.30<br />

Cattle 2 FD 283 d 7 mo JV M GRO BDWT WO — 15.0<br />

Rat 3 DR 92 d 25 d GE F MPH GMPH TB — 28.7<br />

Rat 4 DR 7 d 25 d GE F GRO BDWT WO — 29.0<br />

Rat 2 DR 5 d 26 d JV F GRO BDWT WO — 29.0<br />

Rat 2 DR 26 d 22 d JV F GRO BDWT WO — 29.5<br />

Rat 2 DR 14 d 26 d JV F MPH Other TA — 29.9<br />

Rat 2 DR 10 d 26 d JV F GRO BDWT WO — 30.4<br />

Mouse 2 GV 3 w NR NR JV M GRO BDWT WO — 46.4<br />

Dog 2 OR 5 w


AX7-80<br />

Mammalia<br />

n Species<br />

No. <strong>of</strong><br />

Doses<br />

Table AX7-1.3.4 (cont’d). Mammalian Toxicity Data Used to Develop the Eco-SSL<br />

Route <strong>of</strong><br />

Exposure<br />

Exposure<br />

Duration<br />

Duration<br />

Units Age<br />

Age<br />

Units Lifestage Sex<br />

Effec<br />

t<br />

Type<br />

Effect<br />

Measur<br />

e<br />

Response<br />

Site<br />

NOAEL<br />

(mg/kg<br />

bw/day)<br />

Mouse 2 DR 45 d 50-100 d GE F GRO BDWT WO — 404<br />

Rat 4 FD 1 w NR NR LC F GRO BDWT WO — 442<br />

Rat 2 DR 6 w 14 w LC F GRO BDWT WO — 638<br />

Mouse 4 DR 10 w 11 w JV F GRO BDWT WO — 748<br />

Rat 2 FD 21 d NR NR LC F GRO BDWT WO — 991<br />

Rat 2 GV 18 d 2 d JV B GRO BDWT WO — 1000<br />

Rat 2 FD 2 w 0 d JV NR GRO BDWT WO — 1430<br />

Rat 4 GV 14 d 24 d JV NR GRO BDWT WO — 1600<br />

Rat 2 FD 2 w 60-80 d JV M GRO BDWT WO — 2390<br />

Rat 3 GV 14 d 16 d JV NR GRO BDWT WO — 2400<br />

Rat 2 FD 14 d 60 d JV M GRO BDWT WO — 2650<br />

AD = adult; B = both; BDWT = body weight changes; d = days; DEYO = death <strong>of</strong> young; DR = drinking water; F = female; FD = food; FERT = fertility; GMPH = general morphology;<br />

GRO = growth; GV = gavage; JV = juvenile; LC = lactation; M = male; MA = mature; mo = months; MPH = morphology; NR = not reported; ODVP = <strong>of</strong>fspring development; OR = other oral;<br />

PG = prostate gland; PROG = progeny counts or numbers; PRWT = progeny weight; RBPH = reproductive behavior; REP = reproduction; RHIS = reproductive organ histology; RSEM = resorbed<br />

embryos; RSUC = reproductive success (general); RT = reproductive tissue; SM = sexually mature; SPCL = sperm cell counts; SPCV = sperm cell viability; TA = tail; TB = tibia; TE = testes;<br />

TEDG = testes degeneration; TEWT = testes weight; w = weeks; WO = whole organism; yr = years.<br />

Source: U.S. Environmental Protection Agency (2005b).<br />

LOAEL<br />

(mg/kg<br />

bw/day)


Figure AX7-1.3.2. Mammalian reproduction and growth toxicity data considered in<br />

development <strong>of</strong> the Eco-SSL.<br />

Source: U.S. Environmental Protection Agency (2005b).<br />

wildlife generally would occur at doses greater than the 2 to 8 mg/kg-day reported to be toxic to<br />

most animals in the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a).<br />

AX7.1.3.4 Recent Studies on the Effects <strong>of</strong> <strong>Lead</strong> on Decomposers<br />

Recent studies on effects <strong>of</strong> Pb to two groups <strong>of</strong> decomposers are summarized in this<br />

subsection. Effects on terrestrial invertebrates, such as earthworms and springtails, are described<br />

first, followed by effects on microorganisms.<br />

Effects on Invertebrates<br />

Since the 1986 <strong>Lead</strong> AQCD, there have been several studies in which terrestrial<br />

invertebrates were exposed to Pb in soil. Many <strong>of</strong> these were reviewed during the development<br />

<strong>of</strong> the Eco-SSLs (U.S. Environmental Protection Agency, 2005b). The relevant in<strong>for</strong>mation<br />

from the Eco-SSL document is described below.<br />

AX7-81


A literature search and review was conducted to identify critical papers published since<br />

2002. Effects on earthworms and other invertebrates observed in studies conducted since the<br />

1986 <strong>Lead</strong> AQCD are similar to those reported previously: mortality and decreased growth and<br />

reproduction (Lock and Janssen, 2002; Davies et al., 2002; Rao et al., 2003; Bongers et al., 2004;<br />

Nursita et al., 2005; U.S. Environmental Protection Agency, 2005b).<br />

The literature search completed <strong>for</strong> terrestrial invertebrate Eco-SSL development<br />

identified 179 papers <strong>for</strong> detailed review, <strong>of</strong> which 13 met the minimum criteria <strong>for</strong> further<br />

consideration (U.S. Environmental Protection Agency, 2005b). Most <strong>of</strong> the 18 ecotoxicological<br />

endpoints that were further evaluated measured reproduction or survival as the ecologically<br />

relevant endpoint. Four <strong>of</strong> these, representing one species under three different pH test<br />

conditions were used to develop the Eco-SSL <strong>of</strong> 1700 mg/kg soil (Table AX7-1.3.5).<br />

Table AX7-1.3.5. Invertebrate Toxicity Data Used to Develop the Eco-SSL<br />

Invertebrate Species Soil pH<br />

Collembola<br />

(Folsomia candida)<br />

% Organic<br />

Matter Toxicity Parameter<br />

AX7-82<br />

Pb in Soil<br />

(mg/kg dw)<br />

6.0 10 MATC 1 (reproduction) 3162<br />

Collembola 4.5 10 MATC (reproduction) 3162<br />

Collembola 5.0 10 MATC (reproduction) 894<br />

Collembola 6.0 10 MATC (reproduction) 894<br />

Geometric Mean 1682<br />

* MATC = Maximum Acceptable Threshold Concentration, or the geometric mean <strong>of</strong> the NOEC (no-observedeffect<br />

concentration) and LOEC (lowest-observed-effect concentration).<br />

Source: U.S. Environmental Protection Agency (2005b).<br />

In a study designed to test the toxicity <strong>of</strong> Pb to the earthworm Eisenia fetida, Davies<br />

et al. (2002) found that the 28-day LC50 (± 95% confidence intervals) <strong>for</strong> Pb in soils<br />

contaminated with Pb(NO3)2 was 4379 ∀ 356 mg/kg. Twenty-eight day EC50 values<br />

(±95% confidence intervals) <strong>for</strong> weight change and cocoon production were 1408 ∀ 198 and


971 ∀ 633 mg/kg, respectively. Significant mortalities were noted at concentrations <strong>of</strong> 2000<br />

mg/kg. These data are consistent with those reported in the Eco-SSL document (U.S.<br />

Environmental Protection Agency, 2005b) <strong>for</strong> the same species <strong>of</strong> earthworm.<br />

Nursita et al. (2005) found no mortality and no adverse effects on reproduction (i.e.,<br />

number <strong>of</strong> juveniles) <strong>of</strong> the collembolan Proisotoma minuta exposed <strong>for</strong> 42 days to 300, 750,<br />

1500, or 3000 mg Pb/kg as Pb-nitrate in an acidic (pH = 4.88) sandy loam soil. It was noted that<br />

the soils were allowed to equilibrate <strong>for</strong> 4 weeks after adding the Pb-nitrate be<strong>for</strong>e the organisms<br />

were added. The observation <strong>of</strong> no effect at 3000 mg/kg is consistent with that <strong>of</strong> Sandifer and<br />

Hopkin (1996). Sandifer and Hopkin (1996) determined a NOEC (no-observed-effect<br />

concentration) and LOEC (lowest-observed-effect concentration) <strong>for</strong> collembolan reproduction<br />

<strong>of</strong> 2000 and 5000 mg/kg, respectively. (A MATC [maximum-acceptable-threshold<br />

concentration] <strong>of</strong> 3162 mg/kg was used to develop the Eco-SSL).<br />

The remaining 14 toxicity endpoints that were not used to develop the Eco-SSL <strong>for</strong><br />

invertebrates are presented in Table AX7-1.3.6. None <strong>of</strong> these endpoints was considered eligible<br />

<strong>for</strong> Eco-SSL derivation.<br />

Lock and Janssen (2002) exposed the potworm Enchytraeus albidus to Pb, as Pb-nitrate.<br />

The 21-day LC50 was 4530 mg/kg, and the 42-day EC50 <strong>for</strong> juvenile reproduction was<br />

320 mg/kg. The F1 generation was then grown to maturity in the same concentration soil and<br />

subsequently used in a reproduction test. The EC50 <strong>for</strong> the F1 generation (394 mg/kg) was<br />

similar to that <strong>of</strong> the P generation. The authors concluded that the two-generation assay did not<br />

increase the sensitivity <strong>of</strong> the test (Lock and Janssen, 2002). None <strong>of</strong> the 18 toxicity endpoints<br />

evaluated in detail during development <strong>of</strong> the Eco-SSLs used this species. The LC50 reported <strong>for</strong><br />

the potworm was higher than reported <strong>for</strong> nematodes and similar to that reported <strong>for</strong> the<br />

earthworm. The EC50 <strong>for</strong> reproduction was lower than reported <strong>for</strong> the earthworm or collembola.<br />

Recent work by Bongers et al. (2004) cautioned against attributing all toxicity observed in<br />

a spiked-soil toxicity test to Pb. They found that the counterion may also contribute to the<br />

toxicity <strong>of</strong> Pb in the springtail Folsomia candida. This may have implications on the<br />

interpretation <strong>of</strong> the Eco-SSL data, because the toxicity <strong>of</strong> the counterion (nitrate) was not taken<br />

into account during Eco-SSL development. Percolation (removal <strong>of</strong> the counterion) had no<br />

statistically significant effect on Pb-chloride toxicity (LC50 = 2900 mg/kg <strong>for</strong> both nonpercolated<br />

and percolated soil; EC50 <strong>for</strong> reproduction = 1900 mg/kg or 2400 mg/kg <strong>for</strong><br />

AX7-83


Table AX7-1.3.6. Invertebrate Toxicity Data Not Used to Develop the Eco-SSL<br />

Invertebrate Species Soil pH<br />

% Organic<br />

Matter<br />

AX7-84<br />

Toxicity<br />

Parameter<br />

Pb in Soil<br />

(mg/kg dw)<br />

Nematode 4 1.14 LC50 285<br />

Nematode 4 1.14 LC50 297<br />

Nematode 4 4.2 LC50 847<br />

Nematode 4 4.2 LC50 1341<br />

Nematode 6.2 1.7 LC50 1554<br />

Nematode 5.1 3.0 LC50 891<br />

Earthworm 6.3 10.0 EC50 1940<br />

Earthworm 6.1 10.0 EC50 1629<br />

Earthworm 6.0 10.0 LC50 3716<br />

Earthworm 6.5 10.0 ILL 1.16<br />

Nematode 4 10 LC50 1434<br />

Nematode 4 10 NOAEC 2235<br />

Nematode 6.1 3.4 LC50 13.9<br />

Nematode 6.2 2.2 LC50 11.6<br />

*NOAEC (no-observed-adverse-effect concentration); LC50 (concentration lethal to 50% <strong>of</strong> test population);<br />

EC50 (effect concentration <strong>for</strong> 50% <strong>of</strong> test population); ILL (incipient lethal level).<br />

Source: U.S. Environmental Protection Agency (2005b).<br />

non-percolated or percolated soil, respectively). However, percolation did have a significant<br />

effect on Pb-nitrate toxicity (LC50 = 980 mg/kg or 2200 mg/kg <strong>for</strong> non-percolated or percolated<br />

soil, respectively; EC50 <strong>for</strong> reproduction = 580 mg/kg or 1700 mg/kg <strong>for</strong> non-percolated or<br />

percolated soil, respectively). <strong>Lead</strong> nitrate was more toxic than Pb-chloride <strong>for</strong> survival and<br />

reproduction. However, the toxicity <strong>of</strong> Pb, from chloride or nitrate, was not significantly<br />

different after the counterion was percolated out <strong>of</strong> the test soil. It is noted that the soil was left<br />

<strong>for</strong> 3 weeks to equilibrate be<strong>for</strong>e testing. Lock and Janssen (2002) also found that Pb-nitrate was<br />

more toxic than Pb-chloride, and they used Pb-nitrate in their experiments because 1000 mg/kg<br />

Pb-chloride did not produce any mortality in their range-finding tests. This difference in


chloride and nitrate toxicity has not been found <strong>for</strong> earthworms (Neuhauser et al., 1985; Bongers<br />

et al., 2004).<br />

Rao et al. (2003) exposed the earthworm Eisenia fetida to Pb-oxide in an artificial soil<br />

with a pH <strong>of</strong> 6 at the LC50 concentration <strong>of</strong> 11 mg/kg. Exposure <strong>for</strong> 14 days resulted in a number<br />

<strong>of</strong> effects including body fragmentation, protrusions, rupture <strong>of</strong> the cuticle, etc. Many <strong>of</strong> these<br />

effects may trigger defensive mechanisms. For example, fragmentation <strong>of</strong> the affected posterior<br />

region was followed by regeneration and a new ectoderm layer was <strong>for</strong>med to cover affected<br />

areas, both <strong>of</strong> which processes may serve to prevent soil bacteria from further affecting the<br />

earthworm (Rao et al., 2003).<br />

Effects on Microorganisms and Microbial Processes<br />

Microorganisms and microbial processes were not included in the Eco-SSL development<br />

process (see Attachment 1-2 <strong>of</strong> OSWER Directive 92857-55 dated November 2003 in U.S.<br />

Environmental Protection Agency [2005a]). Many reasons were given, including that it is<br />

unlikely that site conditions would only pose unacceptable risk to microbes and not be reflected<br />

as unacceptable risks to higher organisms; that the significance <strong>of</strong> laboratory-derived effects data<br />

to the ecosystem is uncertain; and that the spatial (across millimeter distances) and temporal<br />

(within minutes to hours) variation makes understanding ecological consequences challenging.<br />

Microbial endpoints <strong>of</strong>ten vary dramatically based on moisture, temperature, oxygen, and many<br />

non-contaminant factors. There<strong>for</strong>e, the recommendation arising from the Eco-SSL<br />

development process was that risks to microbes or microbial processes not be addressed through<br />

the chemical screening process but that they should be addressed within a site-specific risk<br />

assessment (U.S. Environmental Protection Agency, 2005b).<br />

Few studies on the effects <strong>of</strong> Pb to microbial processes have been published since 1986.<br />

As the direct toxicity to fungi and bacterial populations are difficult to determine and interpret,<br />

indicators <strong>for</strong> soil communities are <strong>of</strong>ten measured as proxies <strong>for</strong> toxicity (e.g., urease activity in<br />

soil). Recent studies <strong>of</strong> this nature (Doelman and Haanstra, 1986; Wilke, 1989; Haanstra and<br />

Doelman, 1991) are summarized in this subsection. The Pb concentrations in these recent<br />

studies (1000 to 5000 mg/kg) are consistent with those reported in the 1986 <strong>Lead</strong> AQCD (U.S.<br />

Environmental Protection Agency, 1986a) as associated with effects on microbial processes<br />

(750 to 7500 mg/kg).<br />

AX7-85


The effects <strong>of</strong> Pb-chloride on the processes <strong>of</strong> nitrification and nitrogen mineralization<br />

were studied in a 28-day experiment by Wilke (1989). The authors reported that nitrification<br />

was increased by 12 and 16% at levels <strong>of</strong> 1000 and 4000 mg/kg, respectively, and that nitrogen<br />

mineralization was reduced by 32 and 44% at concentrations <strong>of</strong> 1000 and 4000 mg/kg,<br />

respectively.<br />

The effects <strong>of</strong> Pb on arylsulfatase (Haanstra and Doelman, 1991) and urease activity<br />

(Doelman and Haanstra, 1986) in soil were investigated. LC50s <strong>for</strong> decreases in arylsulfatase<br />

activity were reported at Pb concentrations <strong>of</strong> 3004 and 4538 mg/kg in a silty loam soil, at pH 6<br />

and 8, respectively. The LC50 <strong>for</strong> a decrease in urease activity was 5060 mg Pb/kg in a sandy<br />

loam soil.<br />

In laboratory microcosm studies Cotrufo et al. (1995) found that decomposition <strong>of</strong> oak<br />

(Quercus ilex) leaf litter was reduced at elevated Pb (~20 mg Pb g !1 C) levels after 8 months<br />

compared to controls (~2 mg Pb g !1 C). The researchers found soil respiration and amount <strong>of</strong><br />

soil mycelia correlated negatively with soil Pb, Zn and Cr concentration.<br />

AX7.1.3.5 Summary<br />

The current document expands upon and updates knowledge related to the effects <strong>of</strong> Pb<br />

on terrestrial primary producers, consumers, and decomposers.<br />

Primary Producers<br />

The effects <strong>of</strong> Pb on terrestrial plants include decreased photosynthetic and transpiration<br />

rates in addition to decreased growth and yield. The phytotoxicity <strong>of</strong> Pb is considered to be<br />

relatively low, and there are few reports <strong>of</strong> phytotoxicity from Pb exposure under field<br />

conditions. Recently, phytotoxicity data were reviewed <strong>for</strong> the development <strong>of</strong> the Eco-SSL<br />

(U.S. Environmental Protection Agency, 2005b). Many <strong>of</strong> the toxicity data presented in the Eco-<br />

SSL document (U.S. Environmental Protection Agency, 2005b) are lower than those discussed in<br />

the 1986 <strong>Lead</strong> AQCD, although both documents acknowledged that toxicity is observed over a<br />

wide range <strong>of</strong> concentrations <strong>of</strong> Pb in soil (tens to thousands <strong>of</strong> mg/kg soil). This may be due to<br />

many factors, such as soil conditions (e.g., pH, organic matter) and differences in bioavailability<br />

<strong>of</strong> the Pb in spiked soils perhaps due to lack <strong>of</strong> equilibration <strong>of</strong> the Pb solution with the soil after<br />

spiking. Most phytotoxicity data continue to be developed <strong>for</strong> agricultural plant species (i.e.,<br />

AX7-86


vegetable and grain crops). Few data are available <strong>for</strong> trees or native herbaceous plants,<br />

although two <strong>of</strong> the five toxicity endpoints used to develop the Eco-SSL were <strong>for</strong> trees and two<br />

were <strong>for</strong> clover.<br />

Consumers<br />

Effects <strong>of</strong> Pb on avian and mammalian consumers include decreased survival,<br />

reproduction, and growth as well as effects on development and behavior. There remain few<br />

field effects data <strong>for</strong> consumers, except from sites with multiple contaminants, <strong>for</strong> which it is<br />

difficult to attribute toxicity specifically to Pb. Avian and mammalian toxicity data recently<br />

were reviewed <strong>for</strong> the development <strong>of</strong> Eco-SSLs (U.S. Environmental Protection Agency,<br />

2005b). Many <strong>of</strong> the toxicity data presented in the Eco-SSL document (U.S. Environmental<br />

Protection Agency, 2005b) are lower than those discussed in the 1986 <strong>Lead</strong> AQCD, although the<br />

<strong>EPA</strong> (U.S. Environmental Protection Agency, 2005b) recognizes that toxicity is observed over a<br />

wide range <strong>of</strong> doses (1000 mg Pb/kg bw-day). Most toxicity data <strong>for</strong> birds have been<br />

derived from chicken and quail studies, and most data <strong>for</strong> mammals have been derived from<br />

laboratory rat and mouse studies. Data derived <strong>for</strong> other species would contribute to the<br />

understanding <strong>of</strong> Pb toxicity, particularly <strong>for</strong> wildlife species with different gut physiologies.<br />

In addition, data derived using environmentally realistic exposures, such as from Pbcontaminated<br />

soil and food, may be recommended. Finally, data derived from inhalation<br />

exposures, which evaluate endpoints such as survival, growth, and reproduction, would<br />

contribute to understanding the implications <strong>of</strong> airborne releases <strong>of</strong> Pb.<br />

Decomposers<br />

Effects <strong>of</strong> Pb on soil invertebrates include decreased survival, growth, and reproduction.<br />

Effects on microorganisms include changes in nitrogen mineralization and enzyme activities.<br />

Recent data on 1986 <strong>Lead</strong> toxicity to soil invertebrates and microorganisms are consistent with<br />

those reported in the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a), with<br />

toxicity generally observed at concentrations <strong>of</strong> hundreds to thousands <strong>of</strong> mg/kg soil. Studies on<br />

microbial processes may be influenced significantly by soil parameters, and the significance <strong>of</strong><br />

the test results is not clear.<br />

AX7-87


Ecological Soil Screening Levels (Eco-SSLs)<br />

Eco-SSLs are concentrations <strong>of</strong> contaminants in soils that would result in little or no<br />

measurable effect on ecological receptors (U.S. Environmental Protection Agency, 2005a). They<br />

were developed following rigorous scientific protocols and were subjected to two rounds <strong>of</strong> peer<br />

review. Due to conservative modeling assumptions (e.g., metal exists in most toxic <strong>for</strong>m or<br />

highly bioavailable <strong>for</strong>m, high food ingestion rate, high soil ingestion rate) which are common to<br />

screening processes, several Eco-SSLs are derived below the average background soil<br />

concentration <strong>for</strong> a particular contaminant.<br />

The Eco-SSLs <strong>for</strong> terrestrial plants, birds, mammals, and soil invertebrates are 120, 11,<br />

56, and 1700 mg Pb/kg soil, respectively.<br />

AX7.1.4 Effects <strong>of</strong> <strong>Lead</strong> on Natural Terrestrial Ecosystems<br />

The concept that organisms are part <strong>of</strong> larger systems that include both biotic and abiotic<br />

components <strong>of</strong> the environment dates back to the naturalists <strong>of</strong> the Victorian era. However, the<br />

breakthrough in what we now consider the ecosystem approach to ecology occurred in the 1950s<br />

and 1960s when E.P. and H.T. Odum pioneered the quantitative analysis <strong>of</strong> ecosystems<br />

(Odum, 1971). This approach encouraged the calculation <strong>of</strong> energy flows into, out <strong>of</strong>, and<br />

within explicitly defined ecosystems. The rapid development <strong>of</strong> computer technology aided in<br />

the growth <strong>of</strong> ecosystem ecology by allowing the development and use <strong>of</strong> increasingly complex<br />

models <strong>for</strong> estimating fluxes that could not be directly measured.<br />

It was not long be<strong>for</strong>e the quantitative analysis <strong>of</strong> ecosystems was extended to examine<br />

the flows <strong>of</strong> nutrients and other chemical compounds. In temperate terrestrial systems, the<br />

watershed was identified as a convenient and in<strong>for</strong>mative experimental unit (Bormann and<br />

Likens, 1967). A major conceptual breakthrough in the watershed approach was that drainage<br />

water chemistry could be used as an indicator <strong>of</strong> the “health” <strong>of</strong> the ecosystem. In a system<br />

limited by nitrogen, <strong>for</strong> example, elevated concentrations <strong>of</strong> NO3 ! in drainage waters indicate that<br />

the ecosystem is no longer making optimal use <strong>of</strong> available nutrients.<br />

The ecosystem approach can also be used effectively in the study <strong>of</strong> trace element<br />

biogeochemistry. Input-output budgets can be used to determine whether an ecosystem is a net<br />

source or sink <strong>of</strong> a trace element. Changes to the input-output balance over time can be used to<br />

assess the effects <strong>of</strong> natural or experimental changes in deposition, land use, climate, or other<br />

AX7-88


factors. In addition, examination <strong>of</strong> fluxes within the ecosystem (in plant uptake, soil solutions,<br />

etc.) can be used to understand the processes that are most influential in determining the fate and<br />

transport <strong>of</strong> the trace element.<br />

Many published ecosystem studies include data <strong>for</strong> 1 to 3 years, the typical duration <strong>of</strong><br />

research grant funding or doctoral dissertation research. While these studies enrich our<br />

understanding <strong>of</strong> terrestrial ecosystems, the most valuable studies are those that are maintained<br />

over many years. Natural variations in climate, pests, animal migrations, and other factors can<br />

make inferences from short-term studies misleading (Likens, 1989). To nurture long-term<br />

research, the National Science Foundation supports a network <strong>of</strong> Long-Term Ecological<br />

Research (LTER) sites that represent various biomes.<br />

This section describes terrestrial ecosystem research on Pb, focusing on work done since<br />

the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a) and highlighting key<br />

long-term studies. Un<strong>for</strong>tunately, there are few studies that feature long-term data on trace metal<br />

behavior at multiple levels <strong>of</strong> organization. There<strong>for</strong>e, this examination <strong>of</strong> the effects <strong>of</strong> Pb on<br />

terrestrial ecosystems combines insights from long- and short-term investigations as well as<br />

studies at scales including whole ecosystems, communities, populations, and individual species.<br />

AX7.1.4.1 Effects <strong>of</strong> Terrestrial Ecosystem Stresses on <strong>Lead</strong> Cycling<br />

Terrestrial ecosystems may respond to stressors in a variety <strong>of</strong> ways, including reductions<br />

in the vigor and/or growth <strong>of</strong> vegetation, reductions in biodiversity, and effects on microbial<br />

processes. Each <strong>of</strong> these effects may lead to the “leakage” <strong>of</strong> nutrients, especially nitrogen, in<br />

drainage waters. The reduced vigor or growth <strong>of</strong> vegetation results in a lower uptake <strong>of</strong> nitrogen<br />

and other nutrients from soils. Reduced biodiversity accompanied by lower total net primary<br />

productivity <strong>for</strong> the ecosystem would also result in a lower nutrient uptake. Effects <strong>of</strong> stress in<br />

microbial populations are less obvious. If the stress reduces microbial activity rates, then<br />

nutrients bound in soil organic matter (e.g., organic nitrogen compounds) will likely be<br />

mineralized at a lower rate and retained in the system. On the other hand, disturbances such as<br />

clear-cutting, ice-storm damage, and soil freezing can result in substantial nutrient losses from<br />

soils (Bormann et al., 1968; Likens et al., 1969; Mitchell et al., 1996; Gr<strong>of</strong>fman et al., 2001;<br />

Houlton et al., 2003).<br />

AX7-89


Since the movement and fate <strong>of</strong> Pb in terrestrial ecosystems is strongly related to the<br />

organic matter cycle (Section AX7.1.2), stressors that could lead to disruption or alteration <strong>of</strong> the<br />

soil organic matter pool are <strong>of</strong> particular concern in assessing effects <strong>of</strong> ecosystem stress on Pb<br />

cycling. By binding soluble Pb, soil organic matter acts as a barrier to the release <strong>of</strong> Pb to<br />

drainage waters (Wang et al., 1995; Kaste et al., 2003; Watmough and Hutchinson, 2004). As a<br />

result, concentrations <strong>of</strong> Pb in soil solutions and drainage waters tend to be low (Driscoll et al.,<br />

1988; Wang et al., 1995; Bacon and Bain, 1995; Johnson et al., 1995a). Through decomposition<br />

and leaching, soluble organic matter is released to solution, and with it, some Pb is also<br />

mobilized. Wang and Benoit (1996) found that essentially all <strong>of</strong> the Pb in soil solutions in a<br />

hardwood <strong>for</strong>est in New Hampshire was bound to dissolve organic matter (DOM). This release<br />

<strong>of</strong> soluble Pb does not typically result in elevated surface water Pb concentrations, because<br />

(1) organic matter has a relatively long residence time in most temperate soils (Gosz et al., 1976;<br />

Schlesinger, 1997), so only a small fraction <strong>of</strong> the organic matter pool is dissolved at any time;<br />

(2) DOM-Pb complexes solubilized in upper soil horizons may be precipitated or adsorbed lower<br />

in the soil pr<strong>of</strong>ile; (3) the DOM to which Pb is bound may be utilized by microbes, allowing the<br />

associated Pb to bind anew to soil organic matter. Together, these factors tend to moderate the<br />

release <strong>of</strong> Pb to surface waters in temperate terrestrial ecosystems. However, stressors or<br />

disturbances that result in increased release <strong>of</strong> DOM from soils could result in the unanticipated<br />

release <strong>of</strong> Pb to groundwater and/or surface waters.<br />

Acidification<br />

The effect <strong>of</strong> acidification on ecosystem cycling <strong>of</strong> Pb is difficult to predict. Like most<br />

metals, the solubility <strong>of</strong> Pb increases as pH decreases (Stumm and Morgan, 1995), suggesting<br />

that enhanced mobility <strong>of</strong> Pb should be found in ecosystems under acidification stress. However,<br />

Pb is also strongly bound to organic matter in soils and sediments. Reductions in pH may cause<br />

a decrease in the solubility <strong>of</strong> DOM, due to the protonation <strong>of</strong> carboxylic functional groups<br />

(Tipping and Wo<strong>of</strong>, 1990). Because <strong>of</strong> the importance <strong>of</strong> Pb complexation with organic matter,<br />

lower DOM concentrations in soil solution resulting from acidification may <strong>of</strong>fset the increased<br />

solubility <strong>of</strong> Pb and hence decrease the mobility <strong>of</strong> the organically bound metal.<br />

In a study <strong>of</strong> grassland and <strong>for</strong>est soils at the Rothamsted Experiment Station in England,<br />

long-term (i.e., >100 years) soil acidification significantly increased the mobility <strong>of</strong> Pb in the soil<br />

AX7-90


(Blake and Goulding, 2002). However, the increased mobility was only observed in very acid<br />

soils, those with pH <strong>of</strong>


Land Use and Industry<br />

Changes in land use also represent potentially significant changes in the cycling <strong>of</strong><br />

organic matter in terrestrial ecosystems. Conversion <strong>of</strong> pasture and croplands to woodlands<br />

changes the nature and quantity <strong>of</strong> organic matter inputs to the soil. In temperate climates, <strong>for</strong>est<br />

ecosystems tend to accumulate organic matter in an O horizon on the <strong>for</strong>est floor, whereas<br />

organic matter in grasslands and agricultural fields is concentrated in an A horizon at the soil<br />

surface. Andersen et al. (2002) compared the trace metal concentrations in arable fields in<br />

Denmark to nearby sites that had been converted to <strong>for</strong>est land. After 34 years <strong>of</strong> af<strong>for</strong>estation,<br />

the soils showed no significant difference in Pb concentration or fractionation, despite significant<br />

acidification <strong>of</strong> the soils. Af<strong>for</strong>estation had no effect on the soil carbon concentration,<br />

suggesting that land use change may have little effect on Pb cycling unless soil carbon pools are<br />

affected.<br />

Similarly, the introduction <strong>of</strong> industrial activity may have consequences <strong>for</strong> organic<br />

matter cycling, and subsequently, Pb mobilization. In a rare long-term study <strong>of</strong> polluted soils,<br />

Egli et al. (1999) studied the changes in trace metal concentrations in <strong>for</strong>est soils at a site in<br />

western Switzerland between 1969 and 1993. The site is 3 to 6 km downwind from an aluminum<br />

industrial plant that operated between the 1950s and 1991. In the 24-year period <strong>of</strong> study, the<br />

site experienced significant declines in organic carbon in surface (0 to 5 cm depth) and<br />

subsurface (30 to 35 cm) soils. In the 30 to 35 cm layer, the organic carbon concentration<br />

declined by more than 75%. Extractable Pb (using an ammonium acetate and EDTA mixture)<br />

declined by 35% in the same layer. The authors suggested that the Pb lost from the soil had been<br />

organically bound. While this study indicates that loss <strong>of</strong> soil carbon can induce the mobilization<br />

and loss <strong>of</strong> Pb from terrestrial ecosystems, it is also worth noting that the decline in soil Pb was<br />

considerably smaller than the decline in organic carbon. This suggests that Pb mobilized during<br />

organic matter decomposition can resorb to remaining organic matter or perhaps to alternate<br />

binding sites (e.g., Fe and Mn oxides).<br />

The effects <strong>of</strong> industries that emit Pb to the atmosphere are discussed in Sections<br />

AX7.1.5.2 and AX7.1.5.3 below.<br />

Forest harvesting represents a severe disruption <strong>of</strong> the organic matter cycle in <strong>for</strong>est<br />

ecosystems. Litter inputs are severely reduced <strong>for</strong> several years after cutting (e.g., Hughes and<br />

Fahey, 1994). The removal <strong>of</strong> the <strong>for</strong>est canopy results in reduced interception <strong>of</strong> precipitation,<br />

AX7-92


and, there<strong>for</strong>e, increased water flux to the soil surface. Also, until a new canopy closes, the soil<br />

surface is exposed to increased solar radiation and higher temperatures. Together, the higher<br />

moisture and temperature in surface soils tend to increase the rate <strong>of</strong> organic matter<br />

decomposition. Several studies have estimated decreases <strong>of</strong> up to 40% in the organic matter<br />

content <strong>of</strong> <strong>for</strong>est floor soils after clear-cutting (Covington, 1981; Federer, 1984; Johnson et al.,<br />

1995b). This loss <strong>of</strong> organic matter from the <strong>for</strong>est floor could result in the mobilization <strong>of</strong><br />

organically complexed Pb. However, observations from clear-cut sites in the United States and<br />

Europe indicate that <strong>for</strong>est harvesting causes little or no mobilization <strong>of</strong> Pb from <strong>for</strong>est soils.<br />

At the Hubbard Brook Experimental Forest in New Hampshire, whole-tree harvesting, the<br />

most intensive <strong>for</strong>m <strong>of</strong> clear-cutting, resulted in very small increases in Pb concentrations in soil<br />

solutions draining the Oa soil horizon despite substantial reductions in the organic matter mass <strong>of</strong><br />

that horizon (Fuller et al., 1988; Johnson et al., 1995b). These increases were associated with<br />

similarly small increases in dissolved organic carbon (DOC) concentrations in the Oa horizon<br />

soil water. Output <strong>of</strong> Pb from the watershed stream was unaffected by clear-cutting. Similarly,<br />

Berthelsen and Steinnes (1995) observed small decreases in the Pb content <strong>of</strong> the Oa horizon<br />

(“H” in the European system <strong>of</strong> soil classification) in clear-cut sites in Norway, compared to<br />

uncut reference sites. This mobilization <strong>of</strong> Pb from the Oa horizon was accompanied by an<br />

increase in the Pb content <strong>of</strong> the upper mineral soil horizons. The Pb decline in the Oa horizon<br />

was accompanied by a decrease in the organic matter content, leading the authors to attribute the<br />

Pb dynamics to leaching with DOM. In a study conducted in Wales, Durand et al. (1994)<br />

observed lower Pb outputs from a stream draining a clear-cut watershed than from where the<br />

stream drained the upper reaches <strong>of</strong> the watershed, which were uncut. The DOC and H + outputs<br />

were also lower in the clear-cut area. These patterns persisted in all 5 years <strong>of</strong> the study.<br />

Forest harvesting is a severe <strong>for</strong>m <strong>of</strong> ecosystem disturbance, and, thus, it is somewhat<br />

surprising that studies <strong>of</strong> clear-cutting have shown little or no effect on Pb mobility or loss from<br />

<strong>for</strong>est ecosystems. Perhaps the strong complexation behavior <strong>of</strong> Pb with natural organic matter<br />

results in the retention <strong>of</strong> Pb in <strong>for</strong>est soils. Even in cases where Pb is mobilized in <strong>for</strong>est floor<br />

soils (Fuller et al., 1988; Berthelsen and Steinnes, 1995), there is no evidence <strong>of</strong> loss <strong>of</strong> Pb from<br />

the ecosystem, indicating that mineral soils are efficient in capturing and retaining any Pb that is<br />

mobilized in the <strong>for</strong>est floor. There<strong>for</strong>e, the principal risk associated with <strong>for</strong>est harvesting is the<br />

loss <strong>of</strong> Pb in particulate <strong>for</strong>m to drainage waters through erosion. In some relatively remote<br />

AX7-93


lakes in the United Kingdom the distribution <strong>of</strong> sediment-bound trace elements (including Pb)<br />

have been affected by <strong>for</strong>estry activities and catchment erosion (Yang and Rose, 2005). Yang<br />

and Rose (2005) believe that more contaminated soil in-wash could increase sediment heavy<br />

metal concentrations while less contaminated soil in-wash could dilute sediment heavy metal<br />

levels.<br />

Climate Change<br />

Atmospheric Pb is not likely to contribute significantly to global climate change. <strong>Lead</strong><br />

compounds have relatively short residence times in the atmosphere, making it unlikely that they<br />

will reach the stratosphere. Also, Pb compounds are not known to absorb infrared radiation and,<br />

there<strong>for</strong>e, are unlikely to contribute to stratospheric ozone depletion or global warming.<br />

Climate change does, however, represent a disturbance to terrestrial ecosystems.<br />

Un<strong>for</strong>tunately, the potential linkages between climate-related stress and Pb cycling are poorly<br />

understood. As in the previous examples, effects related to alterations in organic matter cycling<br />

may influence Pb migration. For example, an increase in temperature leading to increased rates<br />

<strong>of</strong> organic matter decomposition could lead to temporary increases in DOM concentrations and<br />

smaller steady-state pools <strong>of</strong> soil organic matter. Either <strong>of</strong> these factors could result in increased<br />

concentrations <strong>of</strong> Pb in waters draining terrestrial ecosystems.<br />

Climate change may also affect the fluctuations <strong>of</strong> temperature and/or precipitation in<br />

terrestrial ecosystems. For example, there is some evidence <strong>for</strong> recent increases in the frequency<br />

<strong>of</strong> soil freezing events in the northeastern United States (Mitchell et al., 1996). Soil freezing<br />

occurs when soils have little or no snow cover to insulate them from cold temperatures and<br />

results in an increased release <strong>of</strong> nitrate and DOC from the O horizons <strong>of</strong> <strong>for</strong>est soils (Mitchell<br />

et al., 1996; Fitzhugh et al., 2001). Increased DOC losses from O horizons subjected to freezing<br />

may also increase Pb mobilization.<br />

Increased fluctuations in precipitation may induce more frequent flooding, with<br />

potentially significant consequences <strong>for</strong> Pb contamination <strong>of</strong> floodplain ecosystems. Soils<br />

collected from the floodplain <strong>of</strong> the Elbe River, in Germany, contained elevated concentrations<br />

<strong>of</strong> Pb and other trace metals (Krηger and Grongr<strong>of</strong>t, 2003). Tissues <strong>of</strong> plants from floodplain<br />

sites did not, however, contain higher Pb concentrations than control sites. More frequent<br />

AX7-94


or more severe flooding would likely result in increased inputs <strong>of</strong> Pb and other metals to<br />

floodplain soils.<br />

AX7.1.4.2 Effects <strong>of</strong> <strong>Lead</strong> Exposure on Natural Ecosystem Structure and Function<br />

The effects <strong>of</strong> Pb exposure on natural ecosystems are confounded by the fact that Pb<br />

exposure cannot be decoupled from other factors that may also affect the ecosystem under<br />

consideration. Principal among these factors are other trace metals and acidic deposition.<br />

Emissions <strong>of</strong> Pb from smelting and other industrial activities are accompanied by other trace<br />

metals (e.g., Zn, Cu, and Cd) and sulfur dioxide (SO2) that may cause toxic effects independently<br />

or in concert with Pb. Reductions in the use <strong>of</strong> alkyl-Pb additives in gasoline have resulted in<br />

significant decreases in Pb deposition to natural ecosystems in the northeastern United States<br />

(Johnson et al., 1995a). However, the period in which Pb deposition has declined (ca. 1975 to<br />

the present) has also seen significant reductions in the acidity (i.e., increased pH) <strong>of</strong> precipitation<br />

in the region (Likens et al., 1996; Driscoll et al., 1998). There<strong>for</strong>e, changes in ecosystem Pb<br />

fluxes may be the result <strong>of</strong> reduced Pb inputs and/or reduced acidity.<br />

Experimental manipulation studies do not suffer from these confounding effects, because<br />

Pb can be added in specific amounts, with or without other compounds. Un<strong>for</strong>tunately,<br />

ecosystem-level manipulations involving Pb additions have not been undertaken. There<strong>for</strong>e, we<br />

must use observations from field studies <strong>of</strong> Pb behavior in sites exposed to various <strong>for</strong>ms <strong>of</strong> Pb<br />

pollution to assess the effects <strong>of</strong> Pb on terrestrial ecosystems. This section includes a discussion<br />

<strong>of</strong> effects <strong>of</strong> Pb in the structure and function <strong>of</strong> terrestrial ecosystems. Effects on energy flows<br />

(food chain effects) and biogeochemical cycling are discussed in Section AX7.1.5.3.<br />

Sites Affected by Nearby Point Sources <strong>of</strong> <strong>Lead</strong><br />

Natural terrestrial ecosystems near smelters, mines, and other industrial plants have<br />

exhibited a variety <strong>of</strong> effects related to ecosystem structure and function. These effects include<br />

decreases in species diversity, changes in floral and faunal community composition, and<br />

decreasing vigor <strong>of</strong> terrestrial vegetation.<br />

All <strong>of</strong> these effects were observed in ecosystems surrounding the Anaconda smelter in<br />

southwestern Montana, which operated between 1884 and 1980 (Galbraith et al., 1995). Soils in<br />

affected areas around the Anaconda smelter were enriched in Pb, arsenic, copper, cadmium, and<br />

AX7-95


zinc; had very low pH; and were determined to be phytotoxic to native vegetation (Kapustka<br />

et al., 1995). The elevated soil arsenic and metal concentrations occurred despite significantly<br />

lower organic matter concentrations in affected soils relative to reference sites (Galbraith et al.,<br />

1995). Line-transect measurements indicated that affected sites had an average <strong>of</strong> 6.9 species per<br />

10-m <strong>of</strong> transect, compared to 20.3 species per 10-m in the reference areas. More than 60% <strong>of</strong><br />

the reference sites supported coniferous (58%) or deciduous (3%) <strong>for</strong>est communities, whereas<br />

less than 1% <strong>of</strong> the affected sites retained functioning <strong>for</strong>est stands. Abundant dead timber and<br />

stumps confirmed that the affected sites were once as <strong>for</strong>ested as the reference sites. Affected<br />

grassland sites were also less diverse and had higher abundances <strong>of</strong> invasive species than<br />

reference grasslands. More than 50% <strong>of</strong> the affected sites were classified as bare ground. The<br />

occurrence <strong>of</strong> bare ground was significantly correlated with the phytotoxicity scores derived by<br />

Kapustka et al. (1995), indicating a link between phytotoxicity and the loss <strong>of</strong> vegetation in the<br />

affected area.<br />

Because <strong>of</strong> the plant community changes near the Anaconda smelter, the vertical diversity<br />

<strong>of</strong> habitats in the affected ecosystems decreased, with only shrubs and soil remaining as viable<br />

habitats. Galbraith et al. (1995) also used the Bureau <strong>of</strong> Land Management’s habitat evaluation<br />

procedure (HEP) to estimate habitat suitability indices (HSI) <strong>for</strong> two indicator species, marten<br />

(Martes americana) and elk (Cervus elaphus). The HSI value ranges from 0 (poor habitat) to<br />

1 (ideal habitat). In sites affected by the Anaconda smelter, HSI values <strong>for</strong> marten averaged 0.0,<br />

compared to 0.5 to 0.8 <strong>for</strong> the reference sites. For elk, affected sites had an average HSI <strong>of</strong> 0.10,<br />

compared to 0.31 at reference sites.<br />

Similar observations were made in the area surrounding Palmerton, Pennsylvania, where<br />

two zinc smelters operated between 1898 and 1980. Soils in the area were enriched in Cd, Zn,<br />

Pb, and Cu, with concentrations decreasing with distance from the smelter sites (Beyer et al.,<br />

1985; Storm et al., 1994). Smelting was determined to be the principal source <strong>of</strong> Pb in soils in<br />

residential and undeveloped areas around Palmerton (Ketterer et al., 2001), which lies on the<br />

north side <strong>of</strong> a gap in Blue Mountain, a ridge running roughly east-west in east-central<br />

Pennsylvania. Much <strong>of</strong> the north-facing side <strong>of</strong> Blue Mountain within 3 km <strong>of</strong> the town is bare<br />

ground or sparsely vegetated, whereas the surrounding natural landscape is predominantly oak<br />

<strong>for</strong>est (Sopper, 1989; Storm et al., 1994). Biodiversity in affected areas is considerably lower<br />

than at reference sites, a pattern attributed to emissions from the smelters (Beyer et al., 1985;<br />

AX7-96


Sopper, 1989). The history is complicated, however, by the land use history <strong>of</strong> the area.<br />

Logging and fire in the early 20th century may also have played a role in the changes in the<br />

terrestrial ecosystems (Jordan, 1975). Extensive logging occurred after the smelters began<br />

operation, suggesting that some <strong>of</strong> the logging may have been salvage logging in affected areas.<br />

Regardless, the smelter emissions appear to have inhibited the regrowth <strong>of</strong> ecosystems compared<br />

to those in nearby unaffected areas. As in Anaconda, MT, the changes in the structure and<br />

function <strong>of</strong> the Palmerton ecosystem changed its suitability as a habitat <strong>for</strong> fauna that would<br />

normally inhabit the area. Storm et al. (1994) did not find amphibians or common invertebrates<br />

in two study sites nearest to the smelters. In the larger study area, they documented elevated<br />

concentrations <strong>of</strong> Pb, Cd, Cu, and Zn in tissues <strong>of</strong> species ranging in size from red-backed<br />

salamanders (Pletheron cenereus) to white-tailed deer (Odocoilius virginianus).<br />

Metal pollution around a Pb-Zn smelter near Bristol, England has not resulted in the loss<br />

<strong>of</strong> oak woodlands within 3 km <strong>of</strong> the smelter, despite significant accumulation <strong>of</strong> Pb, Cd, Cu,<br />

and Zn in soils and vegetation (Martin and Bullock, 1994). However, the high metal<br />

concentrations have favored the growth <strong>of</strong> metal-tolerant species in the woodland.<br />

The effects <strong>of</strong> Pb and other chemical emissions on terrestrial ecosystems near smelters<br />

and other industrial sites decrease downwind from the source. Several studies using the soil<br />

burden as an indicator have shown that much <strong>of</strong> the contamination occurs within a radius <strong>of</strong><br />

20 to 50 km around the emission source (Miller and McFee, 1983; Martin and Bullock, 1994;<br />

Galbraith et al., 1995; Spurgeon and Hopkin, 1996a; see also Section AX7.1.2). For example,<br />

the concentration <strong>of</strong> Pb in <strong>for</strong>est litter declined downwind from a Pb-Zn smelter near Bristol,<br />

UK, from 2330 to 3050 ppm in a stand 2.9 km from the smelter to 45 to 110 ppm in a stand<br />

23 km from the smelter (Martin and Bullock, 1994). Thus, while sites near point sources <strong>of</strong> Pb<br />

may experience pr<strong>of</strong>ound effects on ecosystem structure and function, the extent <strong>of</strong> those effects<br />

is limited spatially. Elevated metal concentrations around smelters have been found to persist<br />

despite significant reductions in emissions (Hrsak et al., 2000). Most terrestrial ecosystems are<br />

far enough from point sources that long-range Pb transport is the primary mechanism <strong>for</strong> Pb<br />

inputs.<br />

AX7-97


Sites Affected by Long-Range <strong>Lead</strong> Transport<br />

Because the effects <strong>of</strong> anthropogenic Pb emissions tend to be restricted in geographic<br />

extent, most natural terrestrial ecosystems in the U.S. sites have Pb burdens derived primarily<br />

from long-range atmospheric transport. Pollutant Pb represents a large fraction <strong>of</strong> the Pb in<br />

many <strong>of</strong> these ecosystems. In particular, many <strong>of</strong> these sites have accumulated large amounts <strong>of</strong><br />

Pb in soils. For example, at the Hubbard Brook Experimental Forest in New Hampshire, the<br />

amount <strong>of</strong> Pb in the <strong>for</strong>est floor was estimated to have increased from about 1.35 kg ha !1 in 1926<br />

(be<strong>for</strong>e the introduction <strong>of</strong> alkyl-Pb additives in gasoline) to 10.5 kg ha !1 in 1977 (Johnson et al.,<br />

1995a). They also estimated the atmospheric Pb deposition from 1926 to 1987 to be 8.7 kg ha !1 ,<br />

an amount that could account <strong>for</strong> nearly all <strong>of</strong> the increase in Pb in the <strong>for</strong>est floor during the<br />

period. The input <strong>of</strong> precipitation Pb to the Hubbard Brook ecosystem in the six decades<br />

spanning 1926 to 1987 was more than half <strong>of</strong> the total Pb estimated to have been released by<br />

mineral weathering in the entire 12,000- to 14,000-year post-glacial period (14.1 kg ha !1 :<br />

[Johnson et al., 2004]). Other studies employing Pb budgets (Miller and Friedland, 1994;<br />

Watmough et al., 2004), and Pb isotopes (Bacon et al., 1995, 1996; Watmough et al., 1998;<br />

Bindler et al., 1999; Hansmann and Köppel, 2000; Kaste et al., 2003), have also shown that<br />

pollutant Pb, primarily from gasoline combustion, represents a quantitatively significant fraction<br />

<strong>of</strong> labile Pb in temperate soils, especially in the upper, organic-rich horizons.<br />

Despite years <strong>of</strong> elevated atmospheric Pb inputs and elevated concentrations in soils, there<br />

is little evidence that sites affected primarily by long-range Pb transport have experienced<br />

significant effects on ecosystem structure or function. Low concentrations <strong>of</strong> Pb in soil<br />

solutions, the result <strong>of</strong> strong complexation <strong>of</strong> Pb by soil organic matter, may explain why few<br />

ecological effects have been observed. At Hubbard Brook, <strong>for</strong> example, the concentration <strong>of</strong> Pb<br />

in soil solutions draining the Oa horizon is


In ecosystems where Pb concentrations in soil solutions are low, toxicity levels <strong>for</strong><br />

vegetation are not likely to be reached regardless <strong>of</strong> the soil Pb concentration. Furthermore,<br />

mycorrhizal infection <strong>of</strong> tree roots appears to reduce the translocation <strong>of</strong> Pb from roots to shoots<br />

(Marschner et al., 1996; Jentschke et al., 1998). In a study <strong>of</strong> mycorrhizal and non-mycorrhizal<br />

Norway spruce (Picea abies (L.) Karst.), mycorrhizal infection <strong>of</strong> roots was not affected by Pb<br />

dose. Some, but not all, species <strong>of</strong> mycorrhizae showed reductions in the amount <strong>of</strong><br />

extrametrical mycelium with Pb exposure but only at solution concentrations <strong>of</strong> 5 µM, a level at<br />

least 50 times greater than typical concentrations in <strong>for</strong>est soils. In a related study, the growth<br />

rate <strong>of</strong> mycorrhizal fungi was unaffected at solution Pb concentrations <strong>of</strong> 1 and 10 µM, but<br />

decreased at 500 µM (Marschner et al., 1999).<br />

Low soil solution Pb concentrations and the influence <strong>of</strong> mycorrhizal symbionts also<br />

result in low uptake <strong>of</strong> Pb by terrestrial vegetation. The net flux <strong>of</strong> Pb into vegetation in the<br />

northern hardwood <strong>for</strong>est at Hubbard Brook in the 1980s was estimated as only 1 g ha !1 year !1<br />

(Johnson et al., 1995a), representing 3% <strong>of</strong> the precipitation input. Klaminder et al. (2005) also<br />

measured a Pb uptake <strong>of</strong> 1 g ha !1 year !1 in a spruce-pine <strong>for</strong>est in northern Sweden. Despite plant<br />

uptake fluxes being very low, they are sensitive to differences and changes in Pb deposition.<br />

Berthelsen et al. (1995) observed decreases in the Pb content <strong>of</strong> stem, twig, leaf, and needle<br />

tissues <strong>of</strong> a variety <strong>of</strong> tree species in Norway between 1982 and 1992, when atmospheric Pb<br />

deposition declined by approximately 70%. They also observed significantly lower Pb<br />

concentrations in tree tissues collected in northern Norway versus southern Norway, where<br />

atmospheric Pb deposition is greater.<br />

Even at subtoxic concentrations, Pb and other metals may influence species diversity in<br />

terrestrial ecosystems. However, little work has been done on the effect <strong>of</strong> low-level metal<br />

concentrations on species diversity. In one study, plant species diversity was positively<br />

correlated to the concentration <strong>of</strong> available Pb in natural and artificial urban meadows in Britain<br />

(McCrea et al., 2004). The authors hypothesized that Pb may inhibit phosphorous uptake by<br />

dominant species, allowing less abundant (but more Pb-tolerant) ones to succeed.<br />

AX7.1.4.3 Effects <strong>of</strong> <strong>Lead</strong> on Energy Flows and Biogeochemical Cycling<br />

In terrestrial ecosystems, energy flow is closely linked to the carbon cycle. The principal<br />

input <strong>of</strong> energy to terrestrial ecosystems is through photosynthesis, in which CO2 is converted to<br />

AX7-99


iomass carbon. Because <strong>of</strong> this link between photosynthesis and energy flow, any effect that Pb<br />

has on the structure and function <strong>of</strong> terrestrial ecosystems (as discussed in Section AX7.1.5.3.)<br />

influences the flow <strong>of</strong> energy into the ecosystem. This section focuses on how Pb influences<br />

energy transfer within terrestrial ecosystems, which begin with the decomposition <strong>of</strong> litter and<br />

other detrital material by soil bacteria and fungi, and cascade through the various components <strong>of</strong><br />

the detrital food web. Because the mobility <strong>of</strong> Pb in soils is closely tied to organic matter<br />

cycling, decomposition processes are central to the biogeochemical cycle <strong>of</strong> Pb. This section<br />

concludes with a discussion <strong>of</strong> how biogeochemical cycling <strong>of</strong> Pb has changed in response to the<br />

changing Pb inputs to terrestrial ecosystems.<br />

Effects <strong>of</strong> <strong>Lead</strong> on Detrital Energy Flows<br />

<strong>Lead</strong> can have a significant effect on energy flows in terrestrial ecosystems. At some sites<br />

severely affected by metal pollution, death <strong>of</strong> vegetation can occur, dramatically reducing the<br />

input <strong>of</strong> carbon to the ecosystem (Jordan, 1975; Galbraith et al., 1995). Subsequently, wind and<br />

erosion may remove litter and humus, leaving bare mineral soil, a nearly sterile environment in<br />

which very little energy transfer can take place (Little and Martin, 1972; Galbraith et al., 1995).<br />

At Pb-affected sites that can retain a functioning <strong>for</strong>est stand, the rate <strong>of</strong> decomposition <strong>of</strong><br />

litter may be reduced, resulting in greater accumulation <strong>of</strong> litter on the <strong>for</strong>est floor than in<br />

unpolluted stands. Numerous investigators have documented significant declines in litter<br />

decomposition rates (Cotrufo et al., 1995; Johnson and Hale, 2004) and/or the rate <strong>of</strong> carbon<br />

respiration (Laskowski et al., 1994; Cotrufo et al., 1995; Saviozzi et al., 1997; Niklínska et al.,<br />

1998; Palmborg et al., 1998; Aka and Darici, 2004) in acid- and metal-contaminated soils or soils<br />

treated with Pb. The resulting accumulation <strong>of</strong> organic matter on the soil surface can be<br />

dramatic. For example, an oak woodland 3 km from a smelter in Bristol, England had a litter<br />

layer mass 10 times greater than the mass in a similar stand 23 km from the smelter (Martin and<br />

Bullock, 1994).<br />

Reduced decomposition rates in polluted ecosystems are the result <strong>of</strong> the inhibition <strong>of</strong> soil<br />

bacteria and fungi and its effects on microbial community structure (Bååth, 1989). Kuperman<br />

and Carreiro (1997) observed 60% lower substrate-induced respiration in heavily polluted<br />

grassland soils near the U.S. Army’s Aberdeen Proving Ground in Maryland. This decline in<br />

carbon respiration was associated with 81% lower bacterial biomass and 93% lower fungal<br />

AX7-100


iomass. Similar declines in the activities <strong>of</strong> carbon-, nitrogen-, and phosphorus-acquiring<br />

enzymes were also observed. Such dramatic effects have only been observed in highly<br />

contaminated ecosystems. In a less contaminated grassland site near a Pb factory in Germany,<br />

Chander et al. (2001) observed a lower ratio <strong>of</strong> microbial biomass carbon to soil organic carbon<br />

in polluted soils. The ratio <strong>of</strong> basal respiration to microbial biomass (the “metabolic quotient,”<br />

qCO2) declined with increasing metal concentration, though this observation depended on the<br />

procedure <strong>for</strong> measuring microbial biomass (substrate-induced respiration versus fumigationextraction).<br />

The combined effect <strong>of</strong> lower microbial biomass per unit soil carbon and similar or<br />

lower qCO2 on polluted sites indicates that the ability <strong>of</strong> soil microorganisms to process carbon<br />

inputs is compromised by metal pollution.<br />

The type <strong>of</strong> ecosystem also plays a role in determining the effects <strong>of</strong> Pb and other metals<br />

on the microbial processing <strong>of</strong> litter. Forest soils in temperate zones accumulate organic matter<br />

at the soil surface to a greater degree than in grasslands. This organic-rich O horizon can support<br />

a large microbial biomass; but it is also an effective trap <strong>for</strong> Pb inputs, because <strong>of</strong> the association<br />

between Pb and soil organic matter. At highly contaminated <strong>for</strong>est sites, microbial biomass and<br />

enzyme activities may be depressed (Fritze et al., 1989; Bååth et al., 1991), causing slower<br />

decomposition <strong>of</strong> the litter.<br />

In addition to effects on decomposition and carbon trans<strong>for</strong>mations, Pb and other trace<br />

metals can also influence key nitrogen cycling processes. Studies in the 1970s demonstrated that<br />

Pb and other metals inhibit the mineralization <strong>of</strong> nitrogen from soil organic matter and<br />

nitrification (Liang and Tabatabai, 1977, 1978), resulting in lower nitrogen availability to plants.<br />

More recent research has documented significant inhibitory effects <strong>of</strong> Pb and other metals on the<br />

activities <strong>of</strong> several enzymes believed to be crucial to nitrogen mineralization in soils (Senwo<br />

and Tabatabai, 1999; Acosta-Martinez and Tabatabai, 2000; Ekenler and Tabatabai, 2002). This<br />

suggests that the inhibitory effect <strong>of</strong> Pb and other metals is broad-based, and not specific to any<br />

particular metabolic pathway. In reducing environments, the rate <strong>of</strong> denitrification is also<br />

depressed by trace metals. Fu and Tabatabai (1989) found that 2.5 µmol g !1 <strong>of</strong> Pb (ca.<br />

500 mg/kg !1 ) was sufficient to cause 0, 27, and 52% decreases in nitrogen reductase activity in<br />

three different soils.<br />

Metal pollution can also affect soil invertebrate populations. Martin and Bullock (1994)<br />

observed lower abundances <strong>of</strong> a variety <strong>of</strong> woodlice, millipedes, spiders, insects, and earthworms<br />

AX7-101


in an oak woodland site 3 km from a Pb-Zn smelter in Bristol, England, compared to a reference<br />

site 23 km from the smelter. The differences were most dramatic when expressed per unit mass<br />

<strong>of</strong> litter. Several species that were abundant in the reference site were not found in the<br />

contaminated woodland. For example, the abundance <strong>of</strong> the woodlice Trichoniscus pusillus<br />

was 151 individuals per m 2 in the reference woodland, but none were found in the contaminated<br />

soils. This was also true <strong>of</strong> 2 <strong>of</strong> the 3 millipede species, and 4 <strong>of</strong> the 5 earthworm species<br />

studied. At six sites within 1 km from the smelters, no earthworms were present at all (Spurgeon<br />

and Hopkin, 1996a). Contamination at this site has apparently reduced both the population and<br />

biodiversity <strong>of</strong> the soil invertebrate community.<br />

The effect <strong>of</strong> metal pollution on soil invertebrates may be a threshold-type response. In a<br />

study conducted in woodlands near two zinc smelters in Noyelles-Godault, in northern France,<br />

soils at the most polluted site were devoid <strong>of</strong> mites and millipedes, while the remaining sites had<br />

diversity measures similar to control sites (Grelle et al., 2000).<br />

While Pb pollution affects the population and diversity <strong>of</strong> soil fauna, there is little<br />

evidence <strong>of</strong> significant bioaccumulation <strong>of</strong> Pb in the soil food web (see also Section AX7.1.3).<br />

In the Bristol, England study, Pb concentrations in earthworms were lower than soil Pb<br />

concentrations and much lower than litter Pb concentrations (Martin and Bullock, 1994). Litterdwelling<br />

mites had Pb concentrations that were 10% <strong>of</strong> the average litter concentration. The<br />

predator centipedes Lithobius <strong>for</strong>ficatus and L. variegatus had mean Pb concentrations <strong>of</strong><br />

18.6 and 44.0 mg kg !1 , respectively, two orders <strong>of</strong> magnitude lower than the Pb concentration <strong>of</strong><br />

litter (2193 mg kg !1 ) and lower than the concentrations <strong>of</strong> their known prey species. In a study<br />

conducted in a Norway spruce <strong>for</strong>est affected primarily by automobile exhaust from a nearby<br />

highway, earthworms had Pb concentrations similar to the soil (Roth, 1993). Almost all <strong>of</strong> the<br />

litter decomposers, however, had Pb concentrations that were less than 20% <strong>of</strong> the litter. All but<br />

3 <strong>of</strong> the zoophagous arthropods had Pb concentrations that were less than 40% <strong>of</strong> their prey; the<br />

remaining 3 had Pb concentrations similar to their prey. Because <strong>of</strong> the absence <strong>of</strong> significant<br />

bioaccumulation in the soil food web, predator species will be affected by Pb pollution primarily<br />

through effects on the abundance <strong>of</strong> their prey (Spurgeon and Hopkin, 1996b).<br />

Taken as a whole, ecosystem-level studies <strong>of</strong> the soil food web indicate that Pb can affect<br />

energy flows in terrestrial ecosystems through two principal mechanisms. In the most severely<br />

polluted sites, the death <strong>of</strong> primary producers directly decreases the flow <strong>of</strong> energy into the<br />

AX7-102


ecosystems. More commonly, the accumulation <strong>of</strong> toxic levels <strong>of</strong> Pb or other metals in litter and<br />

soil decreases the rate <strong>of</strong> litter decomposition through decreases in microbial biomass and/or<br />

respiration. These reductions can subsequently affect higher trophic levels that depend on these<br />

organisms. It is important to note that sites that have exhibited significant disruption to energy<br />

flows and the terrestrial food web are sites that have experienced severe metal contamination and<br />

adverse effects from SO2 from smelters or other metals-related activities.<br />

<strong>Lead</strong> Dynamics in Terrestrial Ecosystems<br />

<strong>Lead</strong> inputs to terrestrial ecosystems in the United States have declined dramatically in the<br />

past 30 years, primarily because <strong>of</strong> the almost complete elimination <strong>of</strong> alkyl-Pb additives in<br />

gasoline in North America. Also, Pb emissions from smelters have declined as older plants have<br />

been shut down or fitted with improved emissions controls. Un<strong>for</strong>tunately, there are few longterm<br />

data sets <strong>of</strong> precipitation inputs to terrestrial ecosystems. At the Hubbard Brook<br />

Experimental Forest, in New Hampshire, Pb input in bulk deposition declined by more than 97%<br />

between 1976 and 1989 (Johnson et al., 1995a). Studies <strong>of</strong> freshwater sediments also indicate a<br />

dramatic decline in Pb inputs since the mid-1970s (Graney et al., 1995; Johnson et al., 1995a;<br />

Farmer et al., 1997; Brännvall et al., 2001a,b).<br />

Reported concentrations <strong>of</strong> Pb in waters draining natural terrestrial ecosystems have<br />

always been low (Wang et al., 1995; Bacon and Bain, 1995; Johnson et al., 1995a; Vinograd<strong>of</strong>f<br />

et al., 2005), generally less than 1 ng L !1 , even at moderately polluted sites (Laskowski et al.,<br />

1995). Consequently, most terrestrial ecosystems in North America and Europe remain sinks <strong>for</strong><br />

Pb despite reductions in atmospheric Pb deposition <strong>of</strong> more than 95%. At Hubbard Brook, <strong>for</strong><br />

example, the input <strong>of</strong> Pb in bulk precipitation declined from 325 g ha !1 year !1 between 1975 and<br />

1977 compared to 29 g ha !1 year !1 between 1985 and 1987 (Johnson et al., 1995a). During the<br />

same period, the output <strong>of</strong> Pb in stream water declined from 6 g ha !1 year !1 to 4 g ha !1 year !1 .<br />

Thus, despite the decline in Pb input, 85% <strong>of</strong> the incoming Pb was still retained in the terrestrial<br />

ecosystem in the later time period. Similar observations have been made in Europe, where the<br />

use <strong>of</strong> leaded gasoline has also declined in the last few decades. At the Glensaugh Research<br />

Station in Scotland, the input <strong>of</strong> Pb to the <strong>for</strong>est ecosystem was estimated as 42.6 g ha !1 year !1<br />

between 2001 and 2003, about six times the stream export <strong>of</strong> 7.2 g ha !1 year !1 (Vinograd<strong>of</strong>f et al.,<br />

2005). Similarly, Huang and Matzner (2004) reported a throughfall flux <strong>of</strong> 16.5 g ha !1 year !1 at<br />

AX7-103


the <strong>for</strong>ested Lehstenbach catchment in Bavaria, about six times the efflux in run<strong>of</strong>f <strong>of</strong> 2.82 g ha !1<br />

year !1 .<br />

<strong>Lead</strong> pollution has resulted in the accumulation <strong>of</strong> large Pb burdens in terrestrial<br />

ecosystems (see also Section AX7.1.2). Despite reductions in emissions, this accumulation <strong>of</strong> Pb<br />

continues, though at markedly lower rates. The large pool <strong>of</strong> Pb bound in soils may potentially<br />

be a threat to aquatic ecosystems (see Section AX7.2), depending on its rate <strong>of</strong> release from the<br />

soil. Early estimates <strong>of</strong> the residence time <strong>of</strong> Pb in the <strong>for</strong>est floor ranged from 220 to 5,000<br />

years (Benninger et al., 1975; Friedland and Johnson, 1985; Turner et al., 1985). However, more<br />

recent literature suggests that Pb is transported more rapidly within soil pr<strong>of</strong>iles than previously<br />

believed. The pool <strong>of</strong> Pb in <strong>for</strong>est floor soils <strong>of</strong> the northeastern United States declined<br />

significantly in the late 20th century. Friedland et al. (1992) reported a 12% decline in the<br />

amount <strong>of</strong> Pb in <strong>for</strong>est floor soils at 30 sites in the region between 1980 and 1990, a much greater<br />

decline than would be expected <strong>for</strong> a pool with a residence time <strong>of</strong> 220 to 5,000 years.<br />

At Hubbard Brook, the pool <strong>of</strong> Pb in the <strong>for</strong>est floor declined by 29% between 1977 and 1987,<br />

an even more rapid rate <strong>of</strong> loss than reported by Friedland et al. (1992). More recently, Evans<br />

et al. (2005) reported significant declines in the Pb content <strong>of</strong> <strong>for</strong>est floor soils in the<br />

northeastern United States and eastern Canada between 1979 and 1996. The magnitude <strong>of</strong> the<br />

decrease in Pb content was greatest at their sites in southern Vermont, and smallest at sites on the<br />

Gaspe Peninsula in Quebec, reflecting the historic gradient in Pb deposition in the region. At the<br />

Vermont site, the Pb concentration in the litter layer (Oi horizon) was 85% lower in 1996 than in<br />

1979. In the Gaspe peninsula <strong>of</strong> Quebec, the decrease was only 50%.<br />

Since drainage water Pb concentrations remain low, the Pb released from <strong>for</strong>est floor soils<br />

in the past has been largely immobilized in mineral soils (Miller and Friedland, 1994; Johnson<br />

et al., 1995a; Johnson and Petras, 1998; Watmough and Hutchinson, 2004; Johnson et al., 2004).<br />

This is supported by evidence from Pb-isotope analyses. Gasoline-derived Pb has a 206 Pb: 207 Pb<br />

ratio that can be easily discriminated from Pb in the rocks from which soils are derived. Using<br />

isotopic mixing models with gasoline-Pb and Pb in soil parent materials as end members,<br />

a number <strong>of</strong> researchers have documented the accumulation <strong>of</strong> pollutant Pb in mineral soils<br />

(Bindler et al., 1999; Kaste et al., 2003; Watmough and Hutchinson, 2004; Bacon and Hewitt,<br />

2005; Steinnes and Friedland, 2005). In a hardwood stand on Camel’s Hump Mountain in<br />

Vermont, as much as 65% <strong>of</strong> the pollutant Pb deposited to the stand had moved into mineral<br />

AX7-104


horizons by 2001 (Kaste et al., 2003). In a spruce-fir stand, containing a thicker organic <strong>for</strong>est<br />

floor layer, penetration <strong>of</strong> pollutant Pb into the mineral soil was much lower.<br />

This recent research has resulted in a reevaluation <strong>of</strong> the turnover time <strong>of</strong> Pb in <strong>for</strong>est<br />

floor soils. The Camel’s Hump data suggest that Pb resides in the <strong>for</strong>est floor <strong>of</strong> deciduous<br />

stands <strong>for</strong> about 60 years and about 150 years in coniferous stands (Kaste et al., 2003). These<br />

values are somewhat greater than those published previously by Miller and Friedland (1994),<br />

who used a Pb budget approach. Extremely rapid turnover <strong>of</strong> Pb was observed in some<br />

hardwood <strong>for</strong>est floor soils in south-central Ontario (Watmough et al., 2004). Their estimated<br />

turnover times <strong>of</strong> 1.8 to 3.1 years are much lower than any other published values, which they<br />

attribute to the mull-type <strong>for</strong>est floor at their sites. Mull-type <strong>for</strong>est floors are normally underlain<br />

by organic-rich A horizons, capable <strong>of</strong> immobilizing Pb released from the <strong>for</strong>est floor. Indeed,<br />

at the same site in Ontario, Watmough and Hutchinson (2004) found that 90% <strong>of</strong> the pollutant Pb<br />

could be found in this A horizon.<br />

The time period over which the accumulated Pb in soils may be released to drainage<br />

waters remains unclear. If Pb moves as a pulse through the soil, there may be a point in the<br />

future at which problematic Pb concentrations occur. However, several authors have argued<br />

against this hypothesis (Wang and Benoit, 1997; Kaste et al., 2003; Watmough et al., 2004),<br />

contending that the strong linkage between Pb and DOM will result in a temporally dispersed<br />

release <strong>of</strong> Pb in the <strong>for</strong>m <strong>of</strong> Pb-DOM complexes. Thus, the greatest threat is likely to be in the<br />

most highly contaminated areas surrounding point sources <strong>of</strong> Pb, where the amount <strong>of</strong> Pb<br />

accumulated in the soil is high, and the death <strong>of</strong> vegetation has resulted in reduced soil organic<br />

matter levels.<br />

AX7.1.4.4 Summary<br />

Atmospheric Pb pollution has resulted in the accumulation <strong>of</strong> Pb in terrestrial ecosystems<br />

throughout the world. In the United States, pollutant Pb represents a significant fraction <strong>of</strong> the<br />

total Pb burden in soils, even in sites remote from smelters and other industrial plants. However,<br />

few significant effects <strong>of</strong> Pb pollution have been observed at sites that are not near point sources<br />

<strong>of</strong> Pb. Evidence from precipitation collection and sediment analyses indicates that atmospheric<br />

deposition <strong>of</strong> Pb has declined dramatically (>95%) at sites unaffected by point sources <strong>of</strong> Pb, and<br />

AX7-105


there is little evidence that Pb accumulated in soils at these sites represents a threat to<br />

groundwaters or surface water supplies.<br />

The highest environmental risk <strong>for</strong> Pb in terrestrial ecosystems exists at sites within about<br />

50 km <strong>of</strong> smelters and other Pb-emitting industrial sites. Assessing the risks specifically<br />

associated with Pb is difficult, because these sites also experience elevated concentrations <strong>of</strong><br />

other metals and because <strong>of</strong> effects related to SO2 emissions. The concentrations <strong>of</strong> Pb in soils,<br />

vegetation, and fauna at these sites can be two to three orders <strong>of</strong> magnitude higher than in<br />

reference areas (see Sections AX7.1.2 and AX7.1.4.2). In the most extreme cases, near smelter<br />

sites, the death <strong>of</strong> vegetation causes a near-complete collapse <strong>of</strong> the detrital food web, creating a<br />

terrestrial ecosystem in which energy and nutrient flows are minimal. More commonly, stress in<br />

soil microorganisms and detritivores can cause reductions in the rate <strong>of</strong> decomposition <strong>of</strong> detrital<br />

organic matter. Although there is little evidence <strong>of</strong> significant bioaccumulation <strong>of</strong> Pb in natural<br />

terrestrial ecosystems, reductions in microbial and detritivorous populations can affect the<br />

success <strong>of</strong> their predators. Thus, at present, industrial point sources represent the greatest Pbrelated<br />

threat to the maintenance <strong>of</strong> sustainable, healthy, diverse, and high-functioning terrestrial<br />

ecosystems in the United States.<br />

AX7.2 AQUATIC ECOSYSTEMS<br />

AX7.2.1 Methodologies Used in Aquatic Ecosystem Research<br />

As discussed in previous sections, aerial deposition is one source <strong>of</strong> Pb deposition to<br />

aquatic systems. Consequently, to develop air quality criteria <strong>for</strong> Pb, consideration must be<br />

given to not only the environmental fate <strong>of</strong> Pb, but also to the environmental effects <strong>of</strong> Pb in the<br />

aquatic environment through consideration <strong>of</strong> laboratory toxicity studies and field evaluations.<br />

Perhaps the most straight<strong>for</strong>ward approach <strong>for</strong> evaluating the effects <strong>of</strong> Pb is to consider extant<br />

criteria <strong>for</strong> Pb in aquatic ecosystems, i.e., water and sediment quality criteria. A key issue in<br />

developing Pb water and sediment criteria that are broadly applicable to a range <strong>of</strong> water bodies<br />

is properly accounting <strong>for</strong> Pb bioavailability and the range in species sensitivities. This section<br />

summarizes how these criteria are derived, the types <strong>of</strong> toxicity studies considered, and key<br />

factors that influence the bioavailability <strong>of</strong> Pb in surface water and sediment to aquatic life.<br />

Because Pb in the aquatic environment is <strong>of</strong>ten associated with other metals (e.g., cadmium,<br />

AX7-106


copper, zinc), the importance <strong>of</strong> considering the toxicity <strong>of</strong> metal mixtures is also discussed.<br />

Finally, some issues related to background Pb concentrations are briefly addressed. It is beyond<br />

the scope <strong>of</strong> this section to review all methodologies in aquatic system research, but good<br />

reviews can be found in summary books, such as Rand et al. (1995).<br />

AX7.2.1.1 Analytical Methods<br />

Common analytical methods <strong>for</strong> measuring Pb in the aquatic environment are summarized<br />

in Table AX7-2.1.1. For relevance to the ambient water quality criteria (AWQC) and sediment<br />

quality criteria <strong>for</strong> Pb discussed below, minimum detection limits should be in the low parts per<br />

billion (ppb) range <strong>for</strong> surface water and the low parts per million (ppm) range <strong>for</strong> sediment.<br />

Table AX7-2.1.1. Common Analytical Methods <strong>for</strong> Measuring <strong>Lead</strong> in Water,<br />

Sediment, and Tissue<br />

Analysis Type Analytical Method<br />

Direct-Aspiration (Flame) Atomic Absorption Spectroscopy<br />

(AAS)<br />

Graphite Furnace Atomic Absorption Spectroscopy<br />

(GFAAS)<br />

Inductively Coupled Plasma<br />

(ICP)<br />

Inductively Coupled Plasma-Mass Spectrometry<br />

(ICP-MS)<br />

AX7-107<br />

<strong>EPA</strong> SW-846 Method 7420 a ,<br />

<strong>EPA</strong> Method 239.1 b ,<br />

Standard Method 3111 c<br />

<strong>EPA</strong> SW-846 Method 7421 a ,<br />

<strong>EPA</strong> Method 239.2 b ,<br />

Standard Method 3113 c<br />

<strong>EPA</strong> SW-846 Method 6010B a ,<br />

<strong>EPA</strong> Method 200.7 b ,<br />

Standard Method 3120 c<br />

<strong>EPA</strong> SW-846 Method 6020 a ,<br />

<strong>EPA</strong> Method 200.8 b<br />

a U.S. Environmental Protection Agency (1986c) Test Methods <strong>for</strong> Evaluating Solid Waste, Physical/Chemical<br />

Methods (SW-846). Third Edition, September 1986; Final Updates I (7/92), <strong>II</strong>A (8/93), <strong>II</strong> (9/94), <strong>II</strong>B (1/95),<br />

<strong>II</strong>I (12/96), <strong>II</strong>IA (4/98), <strong>II</strong>IB (11/04).<br />

b U.S. Environmental Protection Agency (1991) Methods <strong>for</strong> the Determination <strong>of</strong> Metals in Environmental<br />

Samples. <strong>EPA</strong>/600/4-91-010. June 1991 (Supplement I, <strong>EPA</strong>/600/R-94-111, May 1994).<br />

c American Public Health Association (1995) Standard Methods <strong>for</strong> the Examination <strong>of</strong> Water and Wastewater,<br />

19th Edition. American Public Health Association, American Water Works Association, Water Pollution<br />

Control Federation.<br />

In addition to the methods presented in Table AX7-2.1.1, many <strong>of</strong> the methods discussed<br />

in Section AX7.1.1 can be applied to suspended solids and sediments collected from aquatic


ecosystems. Just as in the terrestrial environment, the speciation <strong>of</strong> Pb and other trace metals in<br />

natural freshwaters and seawater plays a crucial role in determining their reactivity, mobility,<br />

bioavailability, and toxicity. Many <strong>of</strong> the same speciation techniques employed <strong>for</strong> the<br />

speciation <strong>of</strong> Pb in terrestrial ecosystems (see Section AX7.1.1 and AX7.1.2) are applicable in<br />

aquatic ecosystems.<br />

There is now a better understanding <strong>of</strong> the potential effects <strong>of</strong> sampling, sample handling,<br />

and sample preparation on aqueous-phase metal speciation. Thus, a need has arisen <strong>for</strong> dynamic<br />

analytical techniques that are able to capture a metal’s speciation, in-situ and in real time. Some<br />

<strong>of</strong> these recently developed dynamic trace metal speciation techniques include:<br />

• Diffusion gradients in thin-film gels (DGT)<br />

• Gel integrated microelectrodes combined with voltammetric in situ pr<strong>of</strong>iling<br />

(GIME-VIP)<br />

• Stripping chronopotentiometry (SCP)<br />

• Flow-through and hollow fiber permeation liquid membranes (FTPLM and HFPLM)<br />

• Donnan membrane technique (DMT)<br />

• Competitive ligand-exchange/stripping voltammetry (CLE-SV)<br />

Various dynamic speciation techniques were compared in a study by Sigg et al. (2006) using<br />

freshwaters collected in Switzerland. They found that techniques involving in-situ measurement<br />

(GIME-VIP) or in-situ exposure (DGT, DMT, and HFPLM) appeared to the most appropriate <strong>for</strong><br />

avoiding Pb and other trace metal speciation artifacts associated sampling and sample handling.<br />

AX7.2.1.2 Ambient Water <strong>Quality</strong> <strong>Criteria</strong>: Development<br />

The <strong>EPA</strong>’s procedures <strong>for</strong> deriving AWQC are described in Stephan et al. (1985) and are<br />

summarized here. With few exceptions, AWQC are derived based on data from aquatic toxicity<br />

studies conducted in the laboratory. In general, both acute (short term) and chronic (long term)<br />

AWQC are developed. Depending on the species, the toxicity studies considered <strong>for</strong> developing<br />

acute criteria range in length from 48 to 96 hours. Acceptable endpoints <strong>for</strong> acute AWQC<br />

development are mortality and/or immobilization, expressed as the median lethal concentration<br />

(LC50) or median effect concentration (EC50). For each species, the geometric mean <strong>of</strong> the<br />

acceptable LC50/EC50 data is calculated to determine the species mean acute value (SMAV).<br />

AX7-108


For each genera, the geometric mean <strong>of</strong> the relevant SMAVs is then calculated to determine the<br />

genus mean acute value (GMAV). The GMAVs are then ranked from high to low, and the final<br />

acute value (FAV; the 5th percentile <strong>of</strong> the GMAVs, based on the four GMAVs surrounding the<br />

5th percentile) is determined. Because the FAV is based on LC50/EC50 values (which represent<br />

unacceptably high levels <strong>of</strong> effect), the FAV is divided by two to estimate a low-effect level.<br />

This value is then termed the acute criterion, or criterion maximum concentration (CMC). Based<br />

on the most recent AWQC document <strong>for</strong> Pb (U.S. Environmental Protection Agency, 1985),<br />

Table AX7-2.1.2 shows the freshwater SMAVs and GMAVs <strong>for</strong> Pb, and the resulting freshwater<br />

CMC. Note that the freshwater AWQC are normalized <strong>for</strong> the hardness <strong>of</strong> the site water, as<br />

discussed further below in Section AX7.2.1.3.<br />

Table AX7-2.1.2. Development <strong>of</strong> Current Acute Freshwater <strong>Criteria</strong> <strong>for</strong> <strong>Lead</strong><br />

(U.S. Environmental Protection Agency, 1985) 1<br />

Rank Species<br />

AX7-109<br />

GMAV<br />

(µg/L)<br />

SMAV<br />

(µg/L)<br />

10 Midge (Tanytarsus dissimilis) 235,900 235,900<br />

9 Goldfish (Carassius auratus) 101,100 101,100<br />

8 Guppy (Poecilia reticulata) 66,140 66,140<br />

7 Bluegill (Lepomis macrochirus) 52,310 52,310<br />

6 Fathead minnow (Pimephales promelas) 25,440 25,440<br />

5 Brook trout (Salvelinus fontinalis) 4,820 4,820<br />

4 Rainbow trout (Oncorhynchus mykiss) 2,448 2,448<br />

3 Snail (Aplexa hypnorum) 1,040 1,040<br />

2 Cladoceran (Daphnia magna) 447.8 447.8<br />

1 Amphipod (Gammarus pseudolimnaeus) 142.6 142.6<br />

1 All values are normalized to a hardness <strong>of</strong> 50 mg/L (see Section AX7.2.1.3).<br />

FAV = 67.54 µg/L<br />

CMC = 33.77 µg/L


To develop chronic AWQC, acceptable chronic toxicity studies should encompass the full<br />

life cycle <strong>of</strong> the test organism, although <strong>for</strong> fish, early life stage or partial life cycle toxicity<br />

studies are considered acceptable. Acceptable endpoints include reproduction, growth and<br />

development, and survival, with the effect levels expressed as the chronic value, which is the<br />

geometric mean <strong>of</strong> the no-observed-effect concentration (NOEC) 1 and the lowest-observed-<br />

effect concentration (LOEC) 2 . Although a chronic criterion could be calculated as the 5th<br />

percentile <strong>of</strong> genus mean chronic values (GMCVs), sufficient chronic toxicity data are generally<br />

lacking, as is the case <strong>for</strong> Pb. Consequently, an acute-chronic ratio (ACR) is typically applied to<br />

the FAV to derive the chronic criterion. As the name implies, the ACR is the ratio <strong>of</strong> the acute<br />

LC50 to the chronic value, based on studies with the same species and in the same dilution water.<br />

For Pb, the final ACR is 51.29, which results in a final chronic value (FCV) <strong>of</strong> 1.317 µg/L (at a<br />

hardness <strong>of</strong> 50 mg/L). The U.S. <strong>EPA</strong> guidelines <strong>for</strong> developing AWQC (Stephan et al., 1985) are<br />

now more than 20 years old and thus are not reflective <strong>of</strong> scientific advances in aquatic<br />

toxicology and risk assessment that have developed since the 1980s. For example, the<br />

toxicological importance <strong>of</strong> dietary metals has been increasingly recognized and approaches <strong>for</strong><br />

incorporating dietary metals into regulatory criteria are being evaluated (Meyer et al., 2005).<br />

Other issues include consideration <strong>of</strong> certain sublethal endpoints that are currently not directly<br />

incorporated into AWQC development (e.g., endocrine toxicity, behavioral responses) and<br />

protection <strong>of</strong> threatened and endangered (T&E) species (U.S. Environmental Protection Agency,<br />

2003). In deriving appropriate and scientifically defensible air quality criteria <strong>for</strong> Pb, it will be<br />

important that the state-<strong>of</strong>-the-science <strong>for</strong> metals toxicity in aquatic systems be incorporated into<br />

the development process.<br />

Subsequent sections summarize some <strong>of</strong> the toxicity studies that meet the AWQC<br />

development guidelines, with an emphasis on key studies published since the last Pb AWQC<br />

were derived in 1984.<br />

1<br />

The NOEC is the highest concentration tested that did not result in statistically significant effects relative<br />

to the control.<br />

2<br />

The LOEC is the lowest concentration tested that resulted in statistically significant effects relative to<br />

the control.<br />

AX7-110


AX7.2.1.3 Ambient Water <strong>Quality</strong> <strong>Criteria</strong>: Bioavailability Issues<br />

In surface waters, the environmental fate <strong>of</strong> metal contaminants is mitigated through<br />

adsorption, complexation, chelation, and other processes that affect bioavailability. The toxicity<br />

<strong>of</strong> divalent cations tends to be highest in s<strong>of</strong>t waters with low concentrations <strong>of</strong> dissolved organic<br />

matter and suspended particles. In an acidic environment (pH


<strong>for</strong> the binding <strong>of</strong> free-metal ion and other metal complexes to the site <strong>of</strong> toxic action in an<br />

organism; and it also considers competition between metal species and other cations (Paquin<br />

et al., 2002). The GSIM is fundamentally similar to the FIAM in that it accounts <strong>for</strong> competition<br />

between metal ions and hardness cations at the physiological active gill sites, but whereas the<br />

FIAM is largely conceptual, the GSIM was used in interpreting toxicity test results <strong>for</strong> individual<br />

metals and metal mixtures (Pagenkopf, 1983). The BLM was adapted from the GSIM and uses<br />

the biotic ligand, rather than the fish gill as the site <strong>of</strong> toxic action (Di Toro et al., 2001; Paquin<br />

et al., 2002). This approach, there<strong>for</strong>e, considers that the external fish gill surface contains<br />

receptor sites <strong>for</strong> metal binding (Schwartz et al., 2004) and that acute toxicity is associated with<br />

the binding <strong>of</strong> metals to defined sites (biotic ligands) on or within the organism (Paquin et al.,<br />

2002). The model is predicated on the theory that mortality (or other toxic effects) occurs when<br />

the concentration <strong>of</strong> metal bound to biotic ligand exceeds a threshold concentration (Di Toro<br />

et al., 2001; Paquin et al., 2002). Free metal cations “out compete” other cations and bind to the<br />

limited number <strong>of</strong> active receptor sites on the gill surface, which may ultimately result in<br />

suffocation and/or disruption <strong>of</strong> ionoregulatory mechanisms in the fish, leading to death (Di Toro<br />

et al., 2001; Paquin et al., 2002). Because the BLM uses the biotic ligand (not the fish gill) as<br />

the site <strong>of</strong> action, the model can be applied to other aquatic organisms, such as crustaceans,<br />

where the site <strong>of</strong> action is directly exposed to the aqueous environment (Di Toro et al., 2001).<br />

Although the BLM is currently being considered as a tool <strong>for</strong> regulating metals on a sitespecific<br />

basis, there are potential limitations in using the BLM to regulate metals in surface<br />

waters that should be understood in developing air quality criteria <strong>for</strong> lead. For example, BLMs<br />

developed to-date have focused on acute mortality/immobilization endpoints <strong>for</strong> fish and<br />

invertebrates. Chronic exposures are typically <strong>of</strong> greatest regulatory concern, but chronic BLMs<br />

to date have received limited attention (De Schamphelaere and Janssen, 2004). In addition,<br />

BLMs account <strong>for</strong> uptake <strong>of</strong> dissolved metal, but dietary metals have also been shown to<br />

contribute to uptake by aquatic biota and, in some cases, increased toxicity. Besser et al. (2005)<br />

observed that chronic (42-day) Pb toxicity to the amphipod Hyalella azteca was greater from a<br />

combined aqueous and dietary exposure than from a water-only exposure and the authors<br />

conclude that estimates <strong>of</strong> chronic toxicity thresholds <strong>for</strong> Pb should consider both aqueous and<br />

dietary exposure routes. The feasibility <strong>of</strong> incorporating dietary metals into BLMs is under<br />

investigation. Another important issue that must be addressed in developing and applying a<br />

AX7-112


BLM in AWQC development is the type <strong>of</strong> dissolved organic matter used in model development<br />

relative to the types <strong>of</strong> dissolved organic matter at the site <strong>of</strong> interest. Richards et al. (2001)<br />

demonstrated that natural organic matter (NOM) <strong>of</strong> different types differentially influenced Pb<br />

and Cu accumulation by gills <strong>of</strong> rainbow trout. There are also other ligands not accounted <strong>for</strong> in<br />

the BLM that require more research. Bianchini and Bowles (2002) emphasized the importance<br />

<strong>of</strong> reduced sulfur as a metal ligand, limitations in scientific knowledge on reduced sulfur, and<br />

provided recommendations <strong>for</strong> studies necessary to incorporate sulfide ligands into the BLM.<br />

The U.S. <strong>EPA</strong> is currently revising the aquatic life AWQC <strong>for</strong> lead, which will include<br />

toxicity data published after the 1985 AWQC were released and incorporation <strong>of</strong> the BLM is<br />

being evaluated. If an acute BLM is incorporated into the revised AWQC <strong>for</strong> lead, the chronic<br />

criteria would likely be estimated using an ACR (the same approach used when the acute<br />

criterion is based on empirical toxicity data; see above).<br />

AX7.2.1.4 Sediment <strong>Quality</strong> <strong>Criteria</strong>: Development and Bioavailability Issues<br />

As with metals in surface waters, the environmental fate <strong>of</strong> metal contaminants in<br />

sediments is moderated through various binding processes that reduce the concentration <strong>of</strong> free,<br />

bioavailable metal. Sediments function as a sink <strong>for</strong> Pb, as with most metals. <strong>Lead</strong> compounds<br />

such as Pb-carbonates, Pb-sulfates, and Pb-sulfides predominate in sediments (Prosi, 1989).<br />

Total Pb has a higher retention time and a higher percentage is retained in sediments compared to<br />

copper and zinc (Prosi, 1989). <strong>Lead</strong> is primarily accumulated in sediments as insoluble Pb<br />

complexes adsorbed to suspended particulate matter. Naturally occurring Pb is bound in<br />

sediments and has a low geochemical mobility (Prosi, 1989). Organic-sulfide and moderately<br />

reducible fractions are less mobile, whereas cation-exchangeable fractions and easily-reducible<br />

fractions are more mobile and more readily bioavailable to biota (Prosi, 1989). Most Pb<br />

transported in surface waters is in a particulate <strong>for</strong>m, originating from the erosion <strong>of</strong> sediments in<br />

rivers or produced in the water column (Prosi, 1989).<br />

Sediment quality criteria have yet to be adopted by the <strong>EPA</strong>, but an equilibrium<br />

partitioning procedure has recently been published (U.S. Environmental Protection Agency,<br />

2005c). The <strong>EPA</strong> has selected an equilibrium partitioning approach because it explicitly<br />

accounts <strong>for</strong> the bioavailability <strong>of</strong> metals. This approach is based on mixtures <strong>of</strong> cadmium,<br />

copper, Pb, nickel, silver, and zinc. Equilibrium partitioning (EqP) theory predicts that metals<br />

AX7-113


partition in sediment between acid-volatile sulfide, pore water, benthic organisms, and other<br />

sediment phases such as organic carbon. When the sum <strong>of</strong> the molar concentrations <strong>of</strong><br />

simultaneously extracted metal (∑SEM) minus the molar concentration <strong>of</strong> AVS is less than zero,<br />

it can accurately be predicted that sediments are not toxic because <strong>of</strong> these metals. Note that this<br />

approach can be used to predict the lack <strong>of</strong> toxicity, but not the presence <strong>of</strong> toxicity. It is<br />

important to emphasize that metals must be evaluated as a mixture using this approach.<br />

If individual metals, or just two or three metals, are measured in sediment, ∑SEM would be<br />

misleadingly small and it may inaccurately appear that ∑SEM / AVS is less than 1.0.<br />

If ∑SEM / AVS is normalized to the organic carbon fraction (i.e., (∑SEM / AVS)/fOC),<br />

mortality can be more reliably predicted by accounting <strong>for</strong> both the site-specific organic carbon<br />

and AVS concentrations. When evaluating a metal mixture containing cadmium, copper, Pb,<br />

nickel, silver, and zinc, the following predictions can be made (U.S. Environmental Protection<br />

Agency, 2005c):<br />

• A sediment with (SEM / AVS)/fOC < 130 µmol/gOC should pose low risk <strong>of</strong> adverse<br />

biological effects due to these metals.<br />

• A sediment with 130 µmol/gOC < (SEM / AVS)/fOC < 3000 µmol/gOC may have adverse<br />

biological effects due to these metals.<br />

• In a sediment with (SEM / AVS)/fOC > 3000 µmol/gOC, adverse biological effects may<br />

be expected.<br />

A third approach is to measure pore water concentrations <strong>of</strong> cadmium, copper, Pb, nickel,<br />

and zinc and then divide the concentrations by their respective FCVs. If the sum <strong>of</strong> these<br />

quotients is


more natural conditions with vertical stratification <strong>of</strong> oxygen concentrations and, hence, varying<br />

levels <strong>of</strong> AVS. The authors concluded that important uncertainties remain in the application <strong>of</strong><br />

the AVS-SEM approach as a regulatory tool. Similarly, some studies suggest that AVS-SEM<br />

measurements in the natural environment must be interpreted cautiously as AVS can be quite<br />

variable with sediment depth and season (Van den Berg et al., 1998). Finally, Long et al. (1998)<br />

critically compared the ability <strong>of</strong> AVS-SEM and dry weight-normalized concentrations to predict<br />

toxicity <strong>of</strong> sediment-associated trace metals. Based on an analysis <strong>of</strong> 77 field-collected sediment<br />

samples, Long et al. (1998) found that dry weight-normalized concentrations were equally or<br />

slightly more accurate than AVS-SEM in predicting non-toxic and toxic results in laboratory<br />

bioassays. Long et al. suggests that a limitation <strong>of</strong> the AVS-SEM approach is that the criteria<br />

were not derived from field studies with mixture <strong>of</strong> toxic chemicals and thus may be less relevant<br />

to sites comprising complex chemical mixtures. Thus, although the AVS-SEM approach <strong>for</strong><br />

developing sediment quality criteria is being pursued by the U.S. <strong>EPA</strong>, there is clearly not<br />

scientific consensus on this approach, at least not <strong>for</strong> all circumstances.<br />

Many alternative approaches <strong>for</strong> developing sediment quality guidelines are based on<br />

empirical correlations between metal concentrations in sediment to associated biological effects,<br />

based on sediment toxicity tests (Long et al., 1995; Ingersoll et al., 1996; MacDonald et al.,<br />

2000). However, these guidelines are based on total metal concentrations in sediment and do not<br />

account <strong>for</strong> the bioavailability <strong>of</strong> metals between sediments. Sediment quality guidelines<br />

proposed <strong>for</strong> Pb from these other sources are shown in Table AX7-2.1.3.<br />

Table AX7-2.1.3. Recommended Sediment <strong>Quality</strong> Guidelines <strong>for</strong> <strong>Lead</strong><br />

Source Water Type Guideline Type Conc. (mg/kg dw)<br />

MacDonald et al. (2000) Freshwater TEC<br />

PEC<br />

Ingersoll et al. (1996) Freshwater ERL<br />

ERM<br />

Long et al. (1995) Saltwater ERL<br />

ERM<br />

AX7-115<br />

35.8<br />

128<br />

55<br />

99<br />

TEC = Threshold effect concentration; PEC = Probable effect concentration; ERL = Effects range – low;<br />

ERM = Effects range – median<br />

46.7<br />

218


AX7.2.1.5 Metal Mixtures<br />

As discussed above, the <strong>EPA</strong>’s current approach <strong>for</strong> developing sediment criteria <strong>for</strong> Pb<br />

and other metals is to consider the molar sum <strong>of</strong> the metal concentrations (∑SEM). Although a<br />

similar approach has not been applied to AWQC, metal mixtures have been shown to be more<br />

toxic than individual metals (Spehar and Fiandt, 1986; Enserink et al., 1991). Spehar and Fiandt<br />

(1986) evaluated the acute and chronic toxicity <strong>of</strong> a metal mixture (arsenic, cadmium, chromium,<br />

copper, mercury, and Pb) to fathead minnows (Pimephales promelas) and a daphnid<br />

(Ceriodaphnia dubia). In acute tests, the joint toxicity <strong>of</strong> these metals was observed to be more<br />

than additive <strong>for</strong> fathead minnows and nearly strictly additive <strong>for</strong> daphnids. In chronic tests, the<br />

joint toxicity <strong>of</strong> the metals was less than additive <strong>for</strong> fathead minnows and nearly strictly<br />

additive <strong>for</strong> daphnids. One approach <strong>for</strong> considering the additive toxicity <strong>of</strong> Pb with other metals<br />

is to use the concept <strong>of</strong> toxic units (TUs). Toxic units <strong>for</strong> each component <strong>of</strong> a metal mixture are<br />

derived by dividing metal concentrations by their respective acute or chronic criterion. The TUs<br />

<strong>for</strong> all the metals in the mixture are then summed. A ∑TU > 1.0 suggests the metal mixture is<br />

toxic (note that this is the same approach as discussed above <strong>for</strong> developing metal sediment<br />

criteria based on pore water concentrations). According to Norwood et al. (2003), the TU<br />

approach is presently the most appropriate model <strong>for</strong> predicting effects <strong>of</strong> metal mixtures based<br />

on the currently available toxicity data. However, it should also be emphasized that the TU<br />

approach is most appropriate at a screening level, because the true toxicity <strong>of</strong> the mixture is<br />

dependent on the relative amounts <strong>of</strong> each metal. The TU approach is also recommended with<br />

mixtures containing less than six metals.<br />

<strong>Lead</strong> and other metals <strong>of</strong>ten co-occur in sediments with other toxicants, such as organic<br />

contaminants. Effects-based sediment quality guidelines (SQGs) have been developed over the<br />

past 20 years to aid in the interpretation <strong>of</strong> the relationships between complex chemical<br />

contamination and adverse biological effects (Long et al., 2006). Mean sediment quality<br />

guideline quotients (mSQGQs) can be calculated by dividing the concentrations <strong>of</strong> chemicals in<br />

sediments by their respective SQGs and then calculating the mean <strong>of</strong> the quotients <strong>for</strong> the<br />

individual chemicals. Long et al. (2006) per<strong>for</strong>med a critical review <strong>of</strong> this approach and found<br />

that it reasonably predicts the incidence and magnitude <strong>of</strong> toxicity in laboratory tests and the<br />

incidence <strong>of</strong> impairment to benthic communities increases incrementally with increasing<br />

mSQGQs. However, the authors pointed out some <strong>of</strong> the limitations <strong>of</strong> this approach, such as a<br />

AX7-116


lack <strong>of</strong> agreement on the level <strong>of</strong> mSQGQs, masking <strong>of</strong> an individual chemical’s effect due to<br />

data aggregation, lack <strong>of</strong> SQGs <strong>for</strong> all chemicals <strong>of</strong> concern, and mSQGQs were not initially<br />

derived as a regulatory standard or criterion, thus there is a reluctance to use them in<br />

en<strong>for</strong>cement or remediation (Long et al., 2006).<br />

For assessing Pb effects on aquatic ecosystems, it is not truly feasible to account <strong>for</strong> metal<br />

mixtures, because these will obviously vary highly from site to site. However, the toxicity <strong>of</strong><br />

metal mixtures in surface water should be considered on a site-specific basis.<br />

AX7.2.1.6 Background <strong>Lead</strong><br />

Because Pb is naturally occurring, it is found in all environmental compartments<br />

including surface water, sediment, and aquatic biota. Background Pb concentrations are spatially<br />

variable depending on geological features and local characteristics that influence Pb speciation<br />

and mobility. In the European Union risk assessments <strong>for</strong> metals, an “added risk” approach has<br />

been considered that assumes only the amount <strong>of</strong> metal added above background is relevant in a<br />

toxicological evaluation. However, this approach ignores the possible contribution <strong>of</strong><br />

background metal levels to toxic effects, and background metal levels are regionally variable,<br />

precluding the approach from being easily transferable between sites. In terms <strong>of</strong> deriving<br />

environmental criteria <strong>for</strong> Pb, background levels should be considered on a site-specific basis if<br />

there is sufficient in<strong>for</strong>mation that Pb concentrations are naturally elevated. As discussed<br />

previously, the use <strong>of</strong> radiogenic Pb isotopes is useful <strong>for</strong> source apportionment.<br />

AX7.2.2 Distribution <strong>of</strong> <strong>Lead</strong> in Aquatic Ecosystems<br />

Atmospheric Pb is delivered to aquatic ecosystems primarily through deposition (wet<br />

and/or dry) or through erosional transport <strong>of</strong> soil particles (Baier and Healy, 1977; Dolske and<br />

Sievering, 1979; and Yang and Rose, 2005). A number <strong>of</strong> physical and chemical factors govern<br />

the fate and behavior <strong>of</strong> Pb in aquatic systems. The <strong>EPA</strong> summarized some <strong>of</strong> these controlling<br />

factors in the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a). For example,<br />

the predominant <strong>for</strong>m <strong>of</strong> Pb in the environment is in the divalent (Pb 2+ ) <strong>for</strong>m and complexation<br />

with inorganic and organic ligands is dependent on pH (Lovering, 1976; Rickard and Nriagu,<br />

1978). A significant portion <strong>of</strong> Pb in the aquatic environment exists in the undissolved <strong>for</strong>m<br />

(i.e., bound to suspended particulate matter). The ratio <strong>of</strong> Pb in suspended solids to Pb in filtrate<br />

AX7-117


varies from 4:1 in rural streams to 27:1 in urban streams (Getz et al., 1977). In still waters, Pb is<br />

removed through sedimentation at a rate determined by temperature, pH, oxidation-reduction<br />

(redox) potential, organic content, grain size, and chemical <strong>for</strong>m <strong>of</strong> Pb in the water and<br />

biological activities (Jenne and Luoma, 1977). Since the publication <strong>of</strong> the 1986 <strong>Lead</strong> AQCD<br />

(U.S. Environmental Protection Agency, 1986a), knowledge <strong>of</strong> the properties <strong>of</strong> Pb in aquatic<br />

ecosystems has expanded. This section will provide further detail on the chemical species and<br />

the environmental factors affecting speciation <strong>of</strong> Pb in the aquatic environment. In addition,<br />

quantitative distributions <strong>of</strong> Pb in water, sediment, and biological tissues will be presented <strong>for</strong><br />

aquatic ecosystems throughout the United States. Finally, recent studies discussing the tracing <strong>of</strong><br />

Pb in aquatic systems will be summarized.<br />

AX7.2.2.1 Speciation <strong>of</strong> <strong>Lead</strong> in Aquatic Ecosystems<br />

The speciation <strong>of</strong> Pb in the aquatic environment is controlled by many factors. The<br />

primary <strong>for</strong>m <strong>of</strong> Pb in aquatic environments is divalent (Pb 2+ ), while Pb 4+ exists only under<br />

extreme oxidizing conditions (Rickard and Nriagu, 1978). Labile <strong>for</strong>ms <strong>of</strong> Pb (e.g., Pb 2+ ,<br />

PbOH + , PbCO3) are a significant portion <strong>of</strong> the Pb inputs to aquatic systems from atmospheric<br />

washout. <strong>Lead</strong> is typically present in acidic aquatic environments as PbSO4, PbCl4, ionic Pb,<br />

cationic <strong>for</strong>ms <strong>of</strong> Pb-hydroxide, and ordinary Pb-hydroxide (Pb(OH)2). In alkaline waters,<br />

common species <strong>of</strong> Pb include anionic <strong>for</strong>ms <strong>of</strong> Pb-carbonate (Pb(CO3)) and Pb(OH)2.<br />

Speciation models have been developed based on the chemical equilibrium model developed by<br />

Tipping (1994) to assist in examining metal speciation. The <strong>EPA</strong> MINTEQA2 computer model<br />

(http://www.epa.gov/ceampubl/mmedia/minteq/) is one such equilibrium speciation model that<br />

can be used to calculate the equilibrium composition <strong>of</strong> dilute aqueous solutions in the laboratory<br />

or in natural aqueous systems. The model is useful <strong>for</strong> calculating the equilibrium mass<br />

distribution among dissolved species, adsorbed species, and multiple solid phases under a variety<br />

<strong>of</strong> conditions, including a gas phase with constant partial pressures. In addition to chemical<br />

equilibrium models, the speciation <strong>of</strong> metals is important from a toxicological perspective.<br />

The BLM was developed to study the toxicity <strong>of</strong> metal ions in aquatic biota and was previously<br />

described in Section AX7.2.1.3. Further detail on speciation models is not provided herein,<br />

rather a general overview <strong>of</strong> major speciation principles are characterized in the following<br />

sections.<br />

AX7-118


Acidity (pH)<br />

Freshwater<br />

Most <strong>of</strong> the Pb in aquatic environments is in the inorganic <strong>for</strong>m (Sadiq, 1992). The<br />

speciation <strong>of</strong> inorganic Pb in freshwater aquatic ecosystems is dependent upon pH and the<br />

available complexing ligands. Solubility varies according to pH, temperature, and water<br />

hardness (Weber, 1993). <strong>Lead</strong> rapidly loses solubility above pH 6.5 (Rickard and Nriagu, 1978)<br />

and as water hardness increases. In freshwaters, Pb typically <strong>for</strong>ms strong complexes with<br />

inorganic OH ! and CO3 2! and weak complexes with Cl ! (Long and Angino, 1977; Bodek et al.,<br />

1988). The primary <strong>for</strong>m <strong>of</strong> Pb at low pH (#6.5) is predominantly Pb 2+ and less abundant<br />

inorganic <strong>for</strong>ms include Pb(HCO)3, Pb(SO4)2 2! , PbCl, PbCO3, and Pb2(OH)2CO3<br />

(Figure AX7-2.2.1). At higher pH (∃7.5), Pb <strong>for</strong>ms hydroxide complexes (PbOH + , Pb(OH)2,<br />

Pb(OH)3 ! , Pb(OH)4 2! ).<br />

Figure AX7-2.2.1. Distribution <strong>of</strong> aqueous lead species as a function <strong>of</strong> pH based on<br />

a concentration <strong>of</strong> 1 µg Pb/L (U.S. Environmental Protection<br />

Agency, 1999).<br />

AX7-119


Organic compounds in surface waters may originate from natural (e.g., humic or fulvic<br />

acids) or anthropogenic sources (e.g., nitrilotriacetonitrile and ethylenediaminetetraacetic acid<br />

[EDTA]) (U.S. Environmental Protection Agency, 1986b). The presence <strong>of</strong> organic complexes<br />

has been shown to increase the rate <strong>of</strong> solution <strong>of</strong> Pb bound as Pb-sulfide (Lovering, 1976).<br />

Soluble organic Pb compounds are present at pH values near 7 and may remain bound at pH<br />

values as low as 3 (Lovering, 1976; Guy and Chakrabarti, 1976). At higher pH (7.4 to 9),<br />

Pb-organic complexes are partially decomposed. Water hardness and pH were found to be<br />

important in Pb-humic acid interactions (O’Shea and Mancy, 1978). An increase in pH<br />

increased the concentration <strong>of</strong> exchangeable Pb complexes, while an increase in hardness tended<br />

to decrease the humic acid-Pb interactions. Thus, the metals involved in water hardness<br />

apparently inhibit the exchangeable interactions between metals and humic acids.<br />

Marine Water<br />

In marine systems, an increase in salinity increases complexing with chloride and<br />

carbonate ions and reduces the amount <strong>of</strong> free Pb 2+ . In seawaters and estuaries at low pH, Pb is<br />

primarily bound to chlorides (PbCl, PbCl2, PbCl3 !� , PbCl4 2! ) and may also <strong>for</strong>m inorganic<br />

Pb(HCO)3, Pb(SO4)2 2! , or PbCO3. Elevated pH in saltwater environments results in the<br />

<strong>for</strong>mation <strong>of</strong> Pb hydroxides (PbOH + , Pb(OH)2, Pb(OH)3 ! , Pb(OH)4 2! ) (Figure AX7-2.2.2).<br />

A recent examination <strong>of</strong> Pb species in seawater as a function <strong>of</strong> chloride concentration suggested<br />

that the primary species were PbCl3 ! > PbCO3 > PbCl2 > PbCl + > and Pb(OH) + (Fernando, 1995).<br />

<strong>Lead</strong> in freshwater and seawater systems is highly complexed with carbonate ligands suggesting<br />

that Pb is likely to be highly available <strong>for</strong> sorption to suspended materials (Long and Angino,<br />

1977).<br />

Current in<strong>for</strong>mation suggests that inorganic Pb is the dominant <strong>for</strong>m in seawater;<br />

however, it has been shown that organically bound Pb complexes make up a large portion <strong>of</strong> the<br />

total Pb (Capodaglio et al., 1990).<br />

Sorption<br />

Sorption processes (i.e., partitioning <strong>of</strong> dissolved Pb to suspended particulate matter or<br />

sediments) appear to exert a dominant effect on the distribution <strong>of</strong> Pb in the environment<br />

(U.S. Environmental Protection Agency, 1979). Sorption <strong>of</strong> Pb results in the enrichment <strong>of</strong><br />

AX7-120


Figure AX7-2.2.2. <strong>Lead</strong> speciation versus chloride content (Fernando, 1995).<br />

bed sediments, particularly in environments with elevated organic matter content from<br />

anthropogenic sources. <strong>Lead</strong> adsorption to aquatic sediments is correlated with pollution in sites<br />

containing high levels <strong>of</strong> anthropogenic organic content, even under acidic conditions (Tada and<br />

Suzuki, 1982; Brook and Moore, 1988; Davis and Galloway, 1993; Botelho et al., 1994; Davis<br />

et al., 1996). Particulate-bound <strong>for</strong>ms are more <strong>of</strong>ten linked to urban run<strong>of</strong>f and mining effluents<br />

(Eisler, 2000).<br />

Solid Pb complexes <strong>for</strong>m when Pb precipitates or adsorbs to suspended particulate matter<br />

and sediments. Inorganic Pb adsorption to suspended organic matter or sediments is dependent<br />

on parameters such as, pH, salinity, water hardness, and the composition <strong>of</strong> the organic matter<br />

(U.S. Environmental Protection Agency, 1979). In addition to suspended organic matter, Pb can<br />

adsorb to bi<strong>of</strong>ilms (i.e., bacteria) (Nelson et al., 1995; Wilson et al., 2001). Adsorption typically<br />

increases with increasing pH, increasing amounts <strong>of</strong> iron or manganese; and with a higher degree<br />

<strong>of</strong> polarity <strong>of</strong> the particulate matter (e.g., clays). Adsorption decreases with water hardness<br />

(Syracuse Research Corporation, 1999). At higher pH, Pb precipitates as Pb(OH) + and PbHCO3 +<br />

into bed sediments (Weber, 1993). Conversely, at low pH, Pb is negatively sorbed (repelled<br />

from the adsorbent surface) (U.S. Environmental Protection Agency, 1979; Gao et al., 2003).<br />

In addition, Pb may be remobilized from sediment with a decrease in metal concentration in the<br />

AX7-121


solution phase, complexation with chelating agents (e.g., EDTA), and changing redox conditions<br />

(Gao et al., 2003). Changes in water chemistry (e.g., reduced pH or ionic composition) can<br />

cause sediment Pb to become remobilized and potentially bioavailable to aquatic organisms<br />

(Weber, 1993).<br />

Biotrans<strong>for</strong>mation<br />

Methylation may result in Pb remobilization and reintroduction into the aqueous<br />

environment compartment and its subsequent release into the atmosphere (Syracuse Research<br />

Corporation., 1999). However, methylation is not a significant environmental pathway<br />

controlling the fate <strong>of</strong> Pb in the aquatic environment. The microbial methylation <strong>of</strong> Pb in aquatic<br />

systems has been demonstrated experimentally, but evidence <strong>for</strong> natural occurrence is limited<br />

(Beijer and Jernelov, 1984; DeJonghe and Adams, 1986). Reisinger et al. (1981) examined the<br />

methylation <strong>of</strong> Pb in the presence <strong>of</strong> numerous bacteria known to alkylate metals and did not find<br />

evidence <strong>of</strong> Pb methylation under any test condition. Tetramethyl-Pb may be <strong>for</strong>med by the<br />

methylation <strong>of</strong> Pb-nitrate or Pb-chloride in sediments (Bodek et al., 1988). However,<br />

tetramethyl-Pb is unstable and may degrade in aerobic environments after being released from<br />

sediments (U.S. Environmental Protection Agency, 1986b). Methylated species <strong>of</strong> Pb may also<br />

be <strong>for</strong>med by the decomposition <strong>of</strong> tetralkyl-Pb compounds (Radojevic and Harrison, 1987;<br />

Rhue et al., 1992). Sadiq (1992) reviewed the methylation <strong>of</strong> Pb compounds and suggested that<br />

chemical methylation <strong>of</strong> Pb is the dominant process and that biomethylation is <strong>of</strong> secondary<br />

importance.<br />

AX7.2.2.2 Spatial Distribution <strong>of</strong> <strong>Lead</strong> in Aquatic Ecosystems<br />

National Water <strong>Quality</strong> Assessment (NAWQA)<br />

The 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986b) did not describe<br />

the distribution and concentration <strong>of</strong> Pb throughout aquatic ecosystems <strong>of</strong> the United States.<br />

Consequently, an analysis <strong>of</strong> readily available data on Pb concentrations was conducted to<br />

determine the distribution <strong>of</strong> Pb in the aquatic environment. Data from the United States<br />

Geological Survey (<strong>US</strong>GS) National Water-<strong>Quality</strong> Assessment (NAWQA) program were<br />

queried and retrieved. NAWQA contains data on Pb concentrations in surface water, bed<br />

sediment, and animal tissue <strong>for</strong> more than 50 river basins and aquifers throughout the country,<br />

AX7-122


and it has been used by the <strong>EPA</strong> <strong>for</strong> describing national environmental concentrations <strong>for</strong> use in<br />

developing AWQC. The authors recognize that the NAWQA program encountered analytical<br />

challenges with the chemical analysis <strong>of</strong> Pb in surface waters. The analytical methods available<br />

during the NAWQA program were not as sensitive as methods currently applied today.<br />

There<strong>for</strong>e, analytical detection limits are elevated and a large portion <strong>of</strong> the data set contains<br />

non-detected values. Nevertheless, this data provides a comprehensive overview <strong>of</strong> Pb<br />

concentrations in U.S. surface waters that is supplemented with data from other relevant studies.<br />

The following sections describe the estimated concentrations <strong>of</strong> Pb from NAWQA and other<br />

research programs.<br />

NAWQA data are collected during long-term, cyclical investigations wherein study units<br />

undergo intensive sampling <strong>for</strong> 3 to 4 years, followed by low-intensity monitoring and<br />

assessment <strong>of</strong> trends every 10 years. The NAWQA program’s first cycle was initiated in 1991;<br />

there<strong>for</strong>e, all available data are less than 15 years old. The second cycle began in 2001 and is<br />

ongoing; data are currently available through 30 September 2003. The NAWQA program study<br />

units were selected to represent a wide variety <strong>of</strong> environmental conditions and contaminant<br />

sources; there<strong>for</strong>e, agricultural, urban, and natural areas were all included. Attention was also<br />

given to selecting sites covering a wide variety <strong>of</strong> hydrologic and ecological resources.<br />

NAWQA sampling protocols are designed to promote data consistency within and among<br />

study units while minimizing local-scale spatial variability. Water-column sampling is<br />

conducted via continuous monitoring, fixed-interval sampling, extreme-flow sampling, as well as<br />

seasonal, high-frequency sampling in order to characterize spatial, temporal, and seasonal<br />

variability as a function <strong>of</strong> hydrologic conditions and contaminant sources. Sediment and tissue<br />

samples are collected during low-flow periods during the summer or fall to reduce seasonal<br />

variability. Where possible, sediment grab samples are collected along a 100-m stream reach,<br />

upstream <strong>of</strong> the location <strong>of</strong> the water-column sampling. Five to ten depositional zones at various<br />

depths, covering left bank, right bank, and center channel, are sampled to ensure a robust<br />

representation <strong>of</strong> each site. Fine-grained samples from the surficial 2 to 3 cm <strong>of</strong> bed sediment at<br />

each depositional zone are sampled and composited. Tissue samples are collected following a<br />

National Target Taxa list and decision trees that help guide selection from that list to<br />

accommodate local variability.<br />

AX7-123


The NAWQA dataset was chosen over other readily available national databases (i.e. the<br />

<strong>US</strong><strong>EPA</strong>-maintained database <strong>for</strong> the STOrage and RETrieval [STORET] <strong>of</strong> chemical, physical,<br />

and biological data), because the study design and methods used to assess the water quality <strong>of</strong><br />

each study unit are rigorous and consistent, and, as such, these data may be presented with a high<br />

level <strong>of</strong> confidence. This is in stark contrast to the STORET database, which essentially serves<br />

as a depot <strong>for</strong> any organization wishing to share data they have generated. This lack <strong>of</strong> a<br />

consistent methodology or QA/QC protocol has lead to the STORET data being highly qualified<br />

and <strong>of</strong>fered with only a mild level <strong>of</strong> confidence. Furthermore, because there is no standard <strong>for</strong><br />

site selection within STORET, the database may be biased toward contaminated sites. Finally,<br />

and, perhaps most importantly, the majority <strong>of</strong> the available Pb data in STORET predate the use<br />

<strong>of</strong> clean techniques <strong>for</strong> Pb quantification.<br />

The authors recognize the existence <strong>of</strong> several local and regional datasets that may be <strong>of</strong><br />

quality equal to NAWQA; however, due to the national scope <strong>of</strong> this assessment, these datasets<br />

were not included in the following statistical analyses. However, because the NAWQA database<br />

does not cover lakes and the marine/estuarine environment, and we were unable to identify any<br />

monitoring data <strong>of</strong> similar quality, local and regional datasets were used in these cases to provide<br />

general in<strong>for</strong>mation on environmental Pb concentrations.<br />

Data Acquisition and Analysis<br />

The following data were downloaded <strong>for</strong> the entire United States (all states) from the<br />

NAWQA website (http://water.usgs.gov/nawqa/index.html): site in<strong>for</strong>mation, dissolved Pb<br />

concentration in surface water (µg/L), total Pb concentration (µg/g) in bed sediment (


Table AX7-2.2.1. NAWQA Land Use Categories and<br />

Natural/Ambient Classification<br />

NAWQA Land Use Categories Classification<br />

Agricultural Ambient<br />

Commercial/Industrial Ambient<br />

Cropland Ambient<br />

Forest Ambient/Natural<br />

Mining Ambient<br />

Mixed Ambient<br />

NA Ambient<br />

Orchard/Vineyard Ambient<br />

Other/Mixed Ambient<br />

Pasture Ambient<br />

Rangeland Ambient/Natural<br />

Reference Ambient/Natural<br />

Residential Ambient<br />

Urban Ambient<br />

Agency, 2004b). Finally, in addition to the natural/ambient classification, tissue samples were<br />

further divided into “whole organism” and “liver” groups.<br />

All data were compiled in spreadsheets wherein non-detect values were converted to one-<br />

half the detection limit and the total number <strong>of</strong> samples, percentage <strong>of</strong> non-detect values (percent<br />

censorship), minimum, maximum, median, mean, standard deviation, and cumulative density<br />

functions were calculated <strong>for</strong> each endpoint <strong>for</strong> both the natural and ambient groups.<br />

As discussed below, some datasets were highly censored; however, deletion <strong>of</strong> non-detect data<br />

has been shown to increase the relative error in the mean to a greater extent than inclusion <strong>of</strong><br />

non-detects as ½ <strong>of</strong> the detection limit (Newman et al., 1989); there<strong>for</strong>e means and other<br />

statistics were calculated using the latter method <strong>for</strong> this analysis. Finally, since all data were<br />

geo-referenced, a geographic in<strong>for</strong>mation system (GIS; ArcGIS) was used to generate maps,<br />

conduct spatial queries and analyses, and calculate statistics.<br />

AX7-125


<strong>Lead</strong> Distributions Generated from the NAWQA Database<br />

Natural versus Ambient Groups<br />

There were four to eight times more ambient surface water (Table AX7-2.2.2) and bulk<br />

sediment (Table AX7-2.2.3) samples in the compiled dataset than natural samples. This is most<br />

likely a function <strong>of</strong> both the NAWQA program site selection process and the fact that sites<br />

unaffected by human activities are extremely limited. The spatial distributions <strong>of</strong> natural and<br />

ambient surface water/sediment sites were fairly comparable, with natural samples located in<br />

almost all <strong>of</strong> the same areas as ambient samples except in the Midwest (Ohio, Illinois, Iowa, and<br />

Michigan), where natural sites were not present (Figure AX7-2.2.3). This exception may be<br />

because these areas are dominated by agricultural and urban areas. The same spatial<br />

distributions were observed <strong>for</strong> the natural and ambient liver and whole organism tissue<br />

samples (Figure AX7-2.2.4 and Figure AX7-2.2.5).<br />

Table AX7-2.2.2. Summary Statistics <strong>of</strong> Ambient and Natural Levels <strong>of</strong><br />

Dissolved <strong>Lead</strong> in Surface Water<br />

AX7-126<br />

Surface Water Dissolved Pb (µg/L)<br />

Statistic Natural Ambient<br />

% Censorship 87.91 85.66<br />

N 430 3445<br />

Minimum 0.04 0.04<br />

Maximum 8.40 29.78<br />

Mean 0.52 0.66<br />

Standard Deviation 0.59 1.20<br />

Median 0.50 0.50<br />

90th Percentile 0.50 0.50<br />

95th Percentile 0.50 1.10<br />

96th Percentile 0.67 2.00<br />

97th Percentile 1.00 2.34<br />

98th Percentile 1.79 3.58<br />

99th Percentile 2.48 5.44


Table AX7-2.2.3. Summary Statistics <strong>of</strong> Ambient and Natural Levels <strong>of</strong> Total <strong>Lead</strong> in<br />


AX7-128<br />

Figure AX7-2.2.3. Spatial distribution <strong>of</strong> natural and ambient surface water/sediment sites (Surface water: natural N = 430,<br />

ambient N = 3445; Sediment: natural N = 258, ambient N = 1466).


AX7-129<br />

Figure AX7-2.2.4. Spatial distribution <strong>of</strong> natural and ambient liver tissue sample sites (Natural N = 83, Ambient N = 559).


AX7-130<br />

Figure AX7-2.2.5. Spatial distribution <strong>of</strong> natural and ambient whole organism tissue sample sites (Natural N = 93,<br />

Ambient N = 332).


Figure AX7-2.2.6. Frequency distribution <strong>of</strong> ambient and natural levels <strong>of</strong> surface water<br />

dissolved lead (µg/L).<br />

Due to the preponderance <strong>of</strong> non-detectable (ND) measurements, assessing national trends<br />

in surface water-dissolved Pb concentrations was not possible. However, areas with elevated Pb<br />

concentrations were identified by classifying the data with detectable Pb concentrations above<br />

and below the 99th percentile. The 99th percentile (versus the 95th percentile) was chosen in<br />

this instance to represent extreme conditions given the small window <strong>of</strong> variability in the dataset.<br />

By convention, the 95th percentile was used in subsequent analyses <strong>of</strong> this type. Areas with high<br />

surface water Pb concentrations were observed in Washington, Idaho, Utah, Colorado, Arkansas,<br />

and Missouri (Figure AX7-2.2.7). The maximum measured Pb concentration was located in<br />

Canyon Creek at Woodland Park, ID, a site classified as mining land use.<br />

Sediment<br />

There were approximately one-half <strong>of</strong> the number <strong>of</strong> surface water data available <strong>for</strong><br />

sediments (N = 1466). In contrast to the surface water data, however, very few sediment data<br />

were below the detection limit (7/1466 ambient ND, 3/258 natural ND; Table AX7-2.2.3).<br />

As expected, the mean ambient Pb concentration was higher than the mean natural Pb<br />

AX7-131


AX7-132<br />

`<br />

Figure AX7-2.2.7. Spatial distribution <strong>of</strong> dissolved lead in surface water (N = 3445).


concentration (120.11 and 109.07 µg/g, respectively). Similarly, the median ambient Pb<br />

concentration was higher than the median natural Pb concentration (28.00 and 22.00 µg/g,<br />

respectively) and the ambient 95th percentile was higher than the natural 95th percentile<br />

(200.00 and 161.50 µg/g, respectively). While the natural and ambient surface water Pb<br />

distributions differed only at the extremes, the natural sediment Pb percentiles were consistently<br />

lower than the ambient percentiles throughout the distributions (Figure AX7-2.2.8). Unlike the<br />

surface water dataset, because the sediment dataset was not heavily censored, assessing national<br />

trends in sediment Pb concentrations was possible. The data were mapped and categorized into<br />

the four quartiles <strong>of</strong> the frequency distribution (Figure AX7-2.2.9). The following observations<br />

were made:<br />

• Sediment Pb concentrations generally increased from west to east (the majority <strong>of</strong><br />

sites along East Coast had Pb concentrations in the fourth quartile <strong>of</strong> the sediment Pb<br />

concentration frequency distribution).<br />

• Several “hot spots” <strong>of</strong> concentrated sites with elevated sediment Pb concentrations<br />

were apparent in various western states.<br />

• Sediment Pb concentrations were generally lowest in the midwestern states<br />

(the majority <strong>of</strong> sites in North Dakota, Nebraska, Minnesota, and Iowa had Pb<br />

concentrations in the first or second quartile <strong>of</strong> sediment Pb concentration<br />

frequency distribution).<br />

As was seen with surface water Pb concentrations, the highest measured sediment Pb<br />

concentrations were found in Idaho, Utah, and Colorado. Not surprisingly, <strong>of</strong> the top 10<br />

sediment Pb concentrations recorded, 7 were measured at sites classified as mining land use.<br />

Tissue<br />

As was true <strong>for</strong> the surface water data, there were a high number <strong>of</strong> tissue samples below<br />

the detection limit (47/93 natural whole organism ND, 130/332 ambient whole organism ND,<br />

74/83 natural liver ND, 398/559 ambient liver ND; Table AX7-2.2.4). In general, more<br />

non-censored data were available <strong>for</strong> whole organism samples than liver samples, and <strong>for</strong><br />

ambient sites than natural sites. As expected, <strong>for</strong> whole organism samples, the 95th percentile Pb<br />

concentration measured at ambient sites was higher than that measured at natural sites (3.24 and<br />

2.50 µg/g, respectively); however, Pb liver concentration 95th percentiles <strong>for</strong> ambient and<br />

natural samples were very similar, with the natural 95th percentile actually higher than the<br />

AX7-133


Figure AX7-2.2.8. Frequency distribution <strong>of</strong> ambient and natural levels <strong>of</strong> bulk sediment<br />


AX7-135<br />

Figure AX7-2.2.9. Spatial distribution <strong>of</strong> total lead in bulk sediment


Table AX7-2.2.4. Summary Statistics <strong>of</strong> Ambient and Natural Levels <strong>of</strong> <strong>Lead</strong><br />

in Whole Organism and Liver Tissues<br />

AX7-136<br />

Tissue Pb (µg/g dry weight)<br />

Whole Organism Liver<br />

Statistic Natural Ambient Natural Ambient<br />

% Censorship 50.54 39.16 89.16 71.20<br />

N 93 332 83 559<br />

Minimum 0.08 0.08 0.01 0.01<br />

Maximum 22.60 22.60 3.37 12.69<br />

Mean 0.95 1.03 0.28 0.36<br />

Standard Deviation 2.53 1.74 0.54 0.96<br />

Median 0.35 0.59 0.11 0.15<br />

90th percentile 1.40 2.27 0.37 0.59<br />

95th percentile 2.50 3.24 1.26 1.06<br />

observed <strong>for</strong> each endpoint (Table AX7-2.2.5). For example, NCBP and NAWQA geometric<br />

mean Pb concentrations were nearly identical (0.55 and 0.54 µg/g dw, respectively) and the<br />

85th percentiles only differed by 0.5 µg Pb/g dw (NCBP, 1.10 and NAWQA, 1.60). The authors<br />

acknowledge that a high degree <strong>of</strong> censorship is present in both <strong>of</strong> these datasets and no firm<br />

conclusions can be drawn by comparing these means. The objective <strong>of</strong> this exercise was limited<br />

to showing how the NAWQA data compare to other national datasets.<br />

As was the case with surface water data, the high amount <strong>of</strong> non-detectable measurements<br />

did not allow <strong>for</strong> a national assessment <strong>of</strong> spatial trends in Pb tissue concentrations. Instead,<br />

areas with high Pb tissue concentrations were identified by classifying the data above and below<br />

the 95th percentile. Similar to surface water and sediments, tissue concentrations were found to<br />

be elevated in Washington, Idaho, Utah, Colorado, Arkansas, and Missouri; however, several <strong>of</strong><br />

the highest measured Pb concentrations were also found in study units in the southwestern and


Figure AX7-2.2.10. Frequency distribution <strong>of</strong> ambient and natural levels <strong>of</strong> lead in liver<br />

tissue (µg/g dry weight).<br />

Figure AX7-2.2.11. Frequency distribution <strong>of</strong> ambient and natural levels <strong>of</strong> lead in whole<br />

organism tissue (µg/g dry weight).<br />

AX7-137


Table AX7-2.2.5. Comparison <strong>of</strong> NCBP and NAWQA Ambient <strong>Lead</strong> Levels<br />

in Whole Organism Tissues<br />

Whole Organism <strong>Lead</strong> Concentration (µg/g dry weight)<br />

Statistic NCBP 1 NAWQA<br />

Geometric Mean 0.55 0.54<br />

Maximum 24.40 22.60<br />

85th Percentile 1.10 1.60<br />

1 To convert between wet and dry weight, wet weight values were multiplied by a factor <strong>of</strong> five.<br />

southeastern states (Figure AX7-2.2.12 and Figure AX7-2.2.13). As expected, the majority <strong>of</strong><br />

the samples with elevated Pb concentrations were taken from sites classified as urban,<br />

commercial/industrial, or mining.<br />

Input and Distribution <strong>of</strong> <strong>Lead</strong> in Other Aquatic Systems<br />

Because the NAWQA database does not cover lakes or the sea where atmospheric<br />

deposition <strong>of</strong> Pb is highly likely, the primary literature was searched <strong>for</strong> studies using ultra-clean<br />

sampling/analytical techniques to characterize Pb concentrations in these environments. <strong>Lead</strong><br />

concentrations in lakes and oceans were generally found to be much lower than those measured<br />

in the lotic waters assessed by NAWQA. Surface water concentrations <strong>of</strong> dissolved Pb measured<br />

in Hall Lake, Washington in 1990 ranged from 2.1 – 1015.3 ng/L (Balistrieri et al., 1994).<br />

Nriagu et al. (1996) found that the average surface water dissolved Pb concentrations measured<br />

in the Great Lakes (Superior, Erie, and Ontario) between 1991 and 1993 were 3.2, 6.0, and<br />

9.9 ng/L, respectively. <strong>Lead</strong> concentrations ranged from 3.2 – 11 ng/L across all three lakes.<br />

Similarly, 101 surface water total Pb concentrations measured at the HOT station ALOHA<br />

between 1998 and 2002 ranged from 25 – 57 pmol/kg (5 – 11 ng/kg; (Boyle et al., 2005). Based<br />

on the fact that Pb is predominately found in the dissolved <strong>for</strong>m in the open ocean (


AX7-139<br />

Figure AX7-2.2.12. Spatial distribution <strong>of</strong> lead in liver tissues (N = 559).


AX7-140<br />

Figure AX7-2.2.13. Spatial distribution <strong>of</strong> lead in whole organism tissues (N = 332).


In open waters <strong>of</strong> the North Atlantic the decline <strong>of</strong> Pb concentrations has been associated<br />

with the phasing out <strong>of</strong> leaded gasoline in North America and western Europe (Véron et al.,<br />

1998). Likewise, Pb restrictions in gasoline appear to have been effective in reducing<br />

atmospheric Pb loading to the Okefenokee Swamp in southern Georgia/northern Florida<br />

(Jackson et al., 2004). Based on sediment cores from the Okefenokee Swamp, Pb concentrations<br />

were approximately 0.5 mg/kg prior to industrial development, reached a maximum <strong>of</strong><br />

approximately 31 mg/kg from about 1935 to 1965, and following passage <strong>of</strong> the Clean <strong>Air</strong> Act in<br />

1970 concentrations have declined to about 18 mg/kg in 1990 (Jackson et al., 2004). Trends in<br />

metals concentrations (roughly 1970-2001) in sediment cores from 35 reservoirs and lakes in<br />

urban and reference settings were analyzed by Mahler et al. (2006) to determine the effects <strong>of</strong><br />

three decades <strong>of</strong> legislation, regulation, and changing demographics and industrial practices in<br />

the United States on concentrations <strong>of</strong> metals in the environment. The researchers found that<br />

decreasing trends outnumbered increasing trends <strong>for</strong> all seven metals analyzed (Cd, Cr, Cu, Pb,<br />

Hg, Ni, and Zn). The most consistent trends were <strong>for</strong> Pb and Cr: For Pb, 83% <strong>of</strong> the lakes had<br />

decreasing trends and 6% had increasing trends; <strong>for</strong> Cr, 54% <strong>of</strong> the lakes had decreasing trends<br />

and none had increasing trends. Mass accumulation rates <strong>of</strong> metals in cores, adjusted <strong>for</strong><br />

background concentrations, decreased from the 1970s to the 1990s, where median changes<br />

ranged from 246% (Pb) to 23% (Hg and Zn). The largest decreases were found in lakes located<br />

in dense urban watersheds where the overall metals contamination in recently deposited<br />

sediments decreased to on-half its 1970s median value. However, Mahler et al. (2006) found<br />

that anthropogenic mass accumulation rates in dense urban lakes remained elevated over those in<br />

lakes in undeveloped watersheds, in some cases by as much as two orders <strong>of</strong> magnitude (Cr, Cu,<br />

and Zn), indicating that urban fluvial source signals can overwhelm those from regional<br />

atmospheric sources. In estuarine systems, however, it appears that similar declines following<br />

the phase-out <strong>of</strong> leaded gasoline are not necessarily as rapid. Steding et al. (2000) used isotopic<br />

evidence to demonstrate the continued cycling <strong>of</strong> Pb in the San Francisco Bay estuary. In the<br />

southern arm <strong>of</strong> San Francisco Bay, which has an average depth <strong>of</strong>


calculations indicate that only a small fraction <strong>of</strong> leaded gasoline fallout from the late 1980s has<br />

been washed out <strong>of</strong> the San Joaquin and Sacramento rivers’ drainage basin by 1995 and<br />

consequently freshwater inputs remain a Pb source to the bay (Steding et al., 2000). The authors<br />

suggest that the continuous source <strong>of</strong> Pb from the river systems draining into the bay, coupled<br />

with benthic remobilization <strong>of</strong> Pb, indicates that historic gasoline deposits may remain in the<br />

combined riparian/estuarine system <strong>for</strong> decades.<br />

AX7.2.2.3 Tracing the Fate and Transport <strong>of</strong> <strong>Lead</strong> in Aquatic Ecosystems<br />

The following section presents a generalized framework <strong>for</strong> the fate and transport <strong>of</strong> Pb in<br />

aquatic systems (Figure AX7-2.2.14). The primary source <strong>of</strong> Pb in natural systems is<br />

atmospheric deposition (Rickard and Nriagu, 1978; U.S. Environmental Protection Agency,<br />

1986a). Estimated median global atmospheric emission <strong>for</strong> anthropogenic and natural sources<br />

are 332 Η 10 6 kg/year and 12 Η 10 6 kg/year, respectively (summarized by Giusti et al., 1993).<br />

Inorganic and metallic Pb compounds are nonvolatile and will partition to airborne particulates<br />

or water vapors (Syracuse Research Corporation., 1999). Dispersion and deposition <strong>of</strong> Pb is<br />

dependent on the particle size (U.S. Environmental Protection Agency, 1986a; Syracuse<br />

Research Corporation., 1999). More soluble <strong>for</strong>ms <strong>of</strong> Pb will be removed from the atmosphere<br />

by washout in rain.<br />

In addition to atmospheric deposition, Pb may enter aquatic ecosystems through industrial<br />

or municipal wastewater effluents, storm water run<strong>of</strong>f, erosion, or direct point source inputs<br />

(e.g., Pb shot or accidental spills). Once in the aquatic environment, Pb will partition between<br />

the various compartments <strong>of</strong> the system (e.g., dissolved phase, solid phase, biota). The<br />

movement <strong>of</strong> Pb between dissolved and particulate <strong>for</strong>ms is governed by factors such as pH,<br />

sorption, and biotrans<strong>for</strong>mation (see Section AX7.2.2.1). <strong>Lead</strong> bound to organic matter will<br />

settle to the bottom sediment layer, be assimilated by aquatic organisms, or be resuspended in the<br />

water column. The uptake, accumulation, and toxicity <strong>of</strong> Pb in aquatic organisms from water<br />

and sediments are influenced by various environmental factors (e.g., pH, organic matter,<br />

temperature, hardness, bioavailability). These factors are further described in Section<br />

AX7.2.3.4). The remainder <strong>of</strong> this section discusses some methods <strong>for</strong> describing the<br />

distribution <strong>of</strong> atmospheric Pb in the aquatic environment.<br />

AX7-142


Figure AX7-2.2.14. <strong>Lead</strong> cycle in an aquatic ecosystem.<br />

Sediment Core Dating and Source Tracing<br />

In addition to directly measuring Pb concentrations in various aquatic compartments (see<br />

Section AX7.2.3.3), it is useful to study the vertical distribution <strong>of</strong> Pb. Sediment pr<strong>of</strong>iling and<br />

core dating is a method used to determine the extent <strong>of</strong> accumulation <strong>of</strong> atmospheric Pb and<br />

provide in<strong>for</strong>mation on potential anthropogenic sources. Sediment concentration pr<strong>of</strong>iles are<br />

typically coupled with Pb isotopic analysis. The isotope fingerprinting method utilizes<br />

measurements <strong>of</strong> the abundance <strong>of</strong> common Pb isotopes (i.e., 204 Pb, 206 Pb, 207 Pb, 208 Pb) to<br />

distinguish between natural Pb over geologic time and potential anthropogenic sources. Details<br />

<strong>of</strong> this method were described in Section AX7.1.2. The concentration <strong>of</strong> isotope 204 Pb has<br />

remained constant throughout time, while the other isotope species can be linked to various<br />

anthropogenic Pb sources. Typically, the ratios or signatures <strong>of</strong> isotopes (e.g., 207 Pb: 206 Pb) are<br />

compared between environmental samples to indicate similarities or differences in the site being<br />

investigated and the potential known sources.<br />

Generally, Pb concentrations in sediment vary with depth. For example, Chow et al.<br />

(1973) examined sediment Pb pr<strong>of</strong>iles in southern Cali<strong>for</strong>nia. <strong>Lead</strong> concentrations were<br />

increased in the shallower sediment depths and comparatively decreased at greater depths. These<br />

changes in sediment vertical concentration were attributed to higher anthropogenic Pb fluxes<br />

AX7-143


from municipal sewage, storm run<strong>of</strong>f, and atmospheric deposition. Similar experiments<br />

conducted throughout the United States have also suggested an increase in Pb concentrations in<br />

the upper sediment layer concomitant with increases in anthropogenic inputs (Bloom and<br />

Crecelius, 1987; Case et al., 1989; Ritson et al., 1999; Chillrud et al., 2003).<br />

Sediment Pb concentration pr<strong>of</strong>iles and isotope analysis have also been used to identify<br />

specific anthropogenic sources. For example, Flegal et al. (1987) used isotopic ratios to trace<br />

sources <strong>of</strong> Pb in mussels from Monterey Bay, CA to a specific slag deposit. Several<br />

investigators have examined isotopic tracers to determine potential regional sources <strong>of</strong> Pb in<br />

eastern North America and the Great Lakes (Flegal et al., 1989b; Graney et al., 1995; Blais,<br />

1996). Water samples from Lake Erie and Lake Ontario were collected and analyzed. <strong>Lead</strong><br />

isotope ratios ( 206 Pb: 207 Pb) from the lakes were compared to known ratios <strong>for</strong> Pb aerosols derived<br />

from industrial sources in Canada and the United States and found to correlate positively. This<br />

indicated that a majority <strong>of</strong> Pb in the lakes was derived from those industrial sources (Flegal<br />

et al., 1989b). Similarly, Gallon et al. (2006) used 206 Pb: 207 Pb ratios in sediment cores collected<br />

from a 300 km transect in Canadian Shield headwater lakes to differentiate Pb contributions from<br />

smelter emissions relative to Pb contributions from other anthropogenic inputs. The authors<br />

were able to estimate the amounts <strong>of</strong> smelter-derived Pb in sediment collected along the 300 km<br />

transect. <strong>Lead</strong> isotopes in sediment cores from Quebec and Ontario, Canada were also used to<br />

distinguish between the amount <strong>of</strong> Pb deposited from local Canadian sources (28.4 to 61.7%)<br />

and U.S. sources (38.3 to 71.6%) (Blais, 1996). Examination <strong>of</strong> Pb isotopes in sediment and<br />

suspended sediment in the St. Lawrence River were used to identify potential anthropogenic Pb<br />

sources from Canada (Gobeil et al., 1995, 2005). Graney et al. (1995) used Pb isotope<br />

measurements to describe the differing historic sources <strong>of</strong> Pb in Lake Erie, Ontario and in<br />

Michigan. Temporal changes in Pb isotopic ratios were found to correspond to sources such as<br />

regional de<strong>for</strong>estation from 1860 through1890, coal combustion and or smelting through 1930,<br />

and the influence <strong>of</strong> leaded gasoline consumption from 1930 to 1980.<br />

The historic record <strong>of</strong> atmospheric Pb pollution has been studied to understand the natural<br />

background Pb concentration and the effects <strong>of</strong> Pb accumulation on ecosystems (Bindler et al.,<br />

1999; Renberg et al., 2000, 2002; Brännvall et al., 2001a,b). The most extensive work in this<br />

area has been conducted at pristine locations in Sweden (Bindler et al., 1999). In this study, soil,<br />

sediment, and tree rings were sampled <strong>for</strong> Pb concentrations and isotopic analyses were<br />

AX7-144


conducted on the soil samples. From this record, historic Pb concentrations and Pb accumulation<br />

rates were estimated. Present day concentrations in the <strong>for</strong>est soils ranged from 40 to 100 mg/kg,<br />

while a natural background concentration was estimated at


AX7.2.3 Aquatic Species Response/Mode <strong>of</strong> Action<br />

Recent advancements in understanding the responses <strong>of</strong> aquatic biota to Pb exposure are<br />

highlighted in this section. A summary <strong>of</strong> the conclusions on the review <strong>of</strong> aquatic responses to<br />

Pb from the appropriate sections <strong>of</strong> the 1986 <strong>Lead</strong> AQCD, <strong>Volume</strong> <strong>II</strong> (U.S. Environmental<br />

Protection Agency, 1986a) and the subsequent conclusions and recommendations contained in<br />

the <strong>EPA</strong> staff review <strong>of</strong> that document (U.S. Environmental Protection Agency, 1990) are also<br />

provided. In addition, this section summarizes research subsequent to the 1986 <strong>Lead</strong> AQCD on<br />

Pb uptake into aquatic biota, effects <strong>of</strong> Pb speciation on uptake, resistance mechanisms to Pb<br />

toxicity, physiological effects <strong>of</strong> Pb, factors that affect responses to Pb, and factors associated<br />

with global climate change. Areas <strong>of</strong> research that are not addressed here include literature<br />

related to exposure to Pb shot or pellets and studies that examine human health-related endpoints<br />

(e.g., hypertension), which are described in other sections <strong>of</strong> this document.<br />

AX7.2.3.1 <strong>Lead</strong> Uptake<br />

<strong>Lead</strong> is nutritionally nonessential and non-beneficial and is toxic to living organisms in all<br />

<strong>of</strong> its <strong>for</strong>ms (Eisler, 2000). <strong>Lead</strong> can bioaccumulate in the tissues <strong>of</strong> aquatic organisms through<br />

ingestion <strong>of</strong> food and water and adsorption from water (Vázquez et al., 1999; Vink, 2002) and<br />

subsequently lead to adverse effects if tissue levels are sufficiently high (see Section AX7.2.5).<br />

Recent research has suggested that due to the low solubility <strong>of</strong> Pb in water, dietary Pb (i.e., lead<br />

adsorbed to sediment, particulate matter, and food) may contribute substantially to exposure and<br />

toxicity in aquatic biota (Besser et al., 2005). Besser et al. (2004) exposed the amphipod<br />

Hyalella azteca to concentrations <strong>of</strong> Pb to evaluate the influence <strong>of</strong> waterborne and dietary Pb<br />

exposure on acute and chronic toxicity. The authors found that acute toxicity was unaffected by<br />

dietary exposure but that dietary Pb exposure did contribute to chronic toxic effects (i.e.,<br />

survival, growth, reproduction) in H. azteca. Field studies in areas affected by metal<br />

contamination (i.e., Clark Fork River, MO; Coeur d’Alene, ID) (Woodward et al., 1994, 1995;<br />

Farag et al., 1994) have also demonstrated the effects <strong>of</strong> dietary metals on rainbow trout.<br />

However, there has been a debate on the importance <strong>of</strong> dietary exposure, as few controlled<br />

laboratory studies have been able to replicate the effects observed in the field studies (Hodson<br />

et al., 1978; Mount, 1994; Erikson, 2001). This may be due to differences in the availability <strong>of</strong><br />

Pb from the dietary sources used in laboratory studies, differences in speciation, and/or<br />

AX7-146


nutritional characteristics <strong>of</strong> the Pb dosed diets. In many field and laboratory studies, dietary<br />

exposure is rarily considered, but food provided to biota in these studies adsorb metals from<br />

water. There<strong>for</strong>e, both dietary and waterborne exposure are occurring and both may be<br />

considered to play roles in eliciting the measured effects.<br />

<strong>Lead</strong> concentrations in the tissues <strong>of</strong> aquatic organisms are generally higher in algae and<br />

benthic organisms and lower in higher trophic-level consumers (Eisler, 2000). Thus, trophic<br />

transfer <strong>of</strong> Pb through food chains is not expected (Eisler, 2000). Metals are not metabolized;<br />

there<strong>for</strong>e, they are good integrative indicators <strong>of</strong> exposure in aquatic biota (Luoma and Rainbow,<br />

2005). Metal uptake is complex, being influenced by geochemistry, route <strong>of</strong> exposure (diet and<br />

adsorption), depuration, and growth (Luoma and Rainbow, 2005). This section discusses the<br />

factors affecting uptake <strong>of</strong> Pb by aquatic biota and the state <strong>of</strong> current research in this area.<br />

As described in Section AX7.2.2.1, the solubility <strong>of</strong> Pb in water varies with pH,<br />

temperature, and ion concentration (water hardness) (Weber, 1993). <strong>Lead</strong> becomes soluble and<br />

bioavailable under conditions <strong>of</strong> low pH, organic carbon content, suspended sediment<br />

concentrations, and ionic concentrations (i.e., low Cd, Ca, Fe, Mn, Zn) (Eisler, 2000). <strong>Lead</strong><br />

rapidly loses solubility above pH 6.5 (Rickard and Nriagu, 1978) and precipitates out as Pb(OH) +<br />

and PbHCO3 + into bed sediments. However, at reduced pH levels or ionic concentrations,<br />

sediment Pb can remobilize and potentially become bioavailable to aquatic organisms (Weber,<br />

1993).<br />

The most bioavailable inorganic <strong>for</strong>m <strong>of</strong> Pb is divalent Pb (Pb 2+ ), which tends to be more<br />

readily assimilated by organisms than complexed <strong>for</strong>ms (Erten-Unal et al., 1998). On the other<br />

hand, the low solubility <strong>of</strong> Pb salts restricts movement across cell membranes, resulting in less<br />

accumulation <strong>of</strong> Pb in fish in comparison to other metals (e.g., Hg, Cu) (Baatrup, 1991).<br />

The accumulation <strong>of</strong> Pb in aquatic organisms is, there<strong>for</strong>e, influenced by water pH, with<br />

lower pHs favoring bioavailability and accumulation. For example, fish accumulated Pb at a<br />

greater rate in acidic lakes (pH = 4.9 to 5.4) than in more neutral lakes (pH = 5.8 to 6.8) (Stripp<br />

et al., 1990). Merlini and Pozzi (1977) found that pumpkinseed sunfish exposed to Pb at pH 6.0<br />

accumulated three-times as much Pb as fish kept at pH 7.5. However, Albers and Camardese<br />

(1993a,b) examined the effects <strong>of</strong> pH on Pb uptake in aquatic plants and invertebrates in acidic<br />

(pH ~5.0) and nonacidic (pH ~6.5) constructed wetlands, ponds, and small lakes in Maine and<br />

Maryland. Their results suggested that low pH had little effect on the accumulation <strong>of</strong> metals by<br />

AX7-147


aquatic plants and insects and on the concentration <strong>of</strong> metals in the waters <strong>of</strong> these aquatic<br />

systems (Albers and Camardese, 1993a,b).<br />

Three geochemical factors that influence metal bioaccumulation in aquatic organisms<br />

include speciation, particulate metal <strong>for</strong>m, and metal <strong>for</strong>m in the tissues <strong>of</strong> prey items (Luoma<br />

and Rainbow, 2005). <strong>Lead</strong> is typically present in acidic aquatic environments as PbSO4, PbCl4,<br />

ionic Pb, cationic <strong>for</strong>ms <strong>of</strong> Pb-hydroxide, and ordinary hydroxide Pb(OH)2. In alkaline waters,<br />

common species <strong>of</strong> Pb include anionic <strong>for</strong>ms <strong>of</strong> Pb-carbonate (Pb(CO3)) and Pb(OH)2. Labile<br />

<strong>for</strong>ms <strong>of</strong> Pb (e.g., Pb 2+ , PbOH + , PbCO3) are a significant portion <strong>of</strong> the Pb inputs to aquatic<br />

systems from atmospheric washout. Particulate-bound <strong>for</strong>ms are more <strong>of</strong>ten linked to urban<br />

run<strong>of</strong>f and mining effluents (Eisler, 2000). Little research has been done to link the complex<br />

concepts <strong>of</strong> chemical speciation and bioavailability in natural systems (Vink, 2002). The<br />

relationship between the geochemistry <strong>of</strong> the underlying sediment and the impact <strong>of</strong> temporal<br />

changes (e.g., seasonal temperatures) to metal speciation are particularly not well studied (Vink,<br />

2002; Hassler et al., 2004).<br />

Generally speaking, aquatic organisms exhibit three Pb accumulation strategies:<br />

(1) accumulation <strong>of</strong> significant Pb concentrations with a low rate <strong>of</strong> loss, (2) excretion <strong>of</strong> Pb<br />

roughly in balance with availability <strong>of</strong> metal in the environment, and (3) weak net accumulation<br />

due to very low metal uptake rate and no significant excretion (Rainbow, 1996). Species that<br />

accumulate nonessential metals such as Pb and that have low rates <strong>of</strong> loss must partition it<br />

internally in such a way that it is sparingly available metabolically. Otherwise, it may cause<br />

adverse toxicological effects (Rainbow, 1996). Aquatic organisms that exhibit this type <strong>of</strong><br />

physiological response have been recommended <strong>for</strong> use both as environmental indicators <strong>of</strong><br />

heavy metal pollution (Borgmann et al., 1993; Castro et al., 1996; Carter and Porter, 1997) and,<br />

in the case <strong>of</strong> macrophytes, as phytoremediators, because they accumulate heavy metals rapidly<br />

from surface water and sediment (Gavrilenko and Zolotukhina, 1989; Simòes Gonçalves et al.,<br />

1991; Carter and Porter, 1997).<br />

Uptake experiments with aquatic plants and invertebrates (e.g., macrophytes,<br />

chironomids, crayfish) have shown steady increases in Pb uptake with increasing Pb<br />

concentration in solution (Knowlton et al., 1983; Timmermans et al., 1992). In crayfish, the<br />

process <strong>of</strong> molting can cause a reduction in body Pb concentrations, as Pb incorporated into the<br />

crayfish shell is eliminated (Knowlton et al., 1983). Vázquez et al. (1999) reported on the uptake<br />

AX7-148


<strong>of</strong> Pb from solution to the extracellular and intracellular compartments <strong>of</strong> 3 species <strong>of</strong> aquatic<br />

bryophytes. Relative to the 6 metals tested, Pb was found to accumulate to the largest degree in<br />

the extracellular compartments <strong>of</strong> all 3 bryophytes. The extracellular metals were defined as<br />

those that are incorporated into the cell wall or are found on the outer surface <strong>of</strong> the plasma<br />

membrane (i.e., adsorbed) (Vázquez et al., 1999). Intracellular metals were defined as metals<br />

introduced into the cell through a metabolically controlled process.<br />

Arai et al. (2002) examined the effect <strong>of</strong> growth on the uptake and elimination <strong>of</strong> trace<br />

metals in the abalone Haliotos. They reported that older abalones had generally lower whole<br />

body concentrations <strong>of</strong> heavy metals than did younger, rapidly growing individuals. During the<br />

rapid growth <strong>of</strong> juveniles, the organism is less able to distinguish between essential (e.g., Zn),<br />

and nonessential metals (e.g., Pb). Once they reach maturity, they develop the ability to<br />

differentiate these metals. Li et al. (2004) reported a similar response in zebra fish embryolarvae.<br />

Li et al. (2004) suggested that mature physiological systems are not developed in the<br />

embryo-larvae to handle elevated concentrations <strong>of</strong> metals. There<strong>for</strong>e, metals are transported<br />

into the body by facilitated diffusion. Both the zebra fish and juvenile abalone demonstrate a<br />

rapid accumulation strategy followed by a low rate <strong>of</strong> loss as described above. There are<br />

insufficient data available to determine whether this phenomenon is true <strong>for</strong> other aquatic<br />

organisms.<br />

Growth rates are generally thought to be an important consideration in the comparison <strong>of</strong><br />

Pb levels in individuals <strong>of</strong> the same species. The larger the individual the more the metal content<br />

is diluted by body tissue (Rainbow, 1996).<br />

Once Pb is absorbed, it may sequester into varying parts <strong>of</strong> the organism. Calcium<br />

appears to have an important influence on Pb transfer. For example, Pb uptake and retention in<br />

the skin and skeleton <strong>of</strong> coho salmon was reduced when dietary Ca was increased (Varanasi and<br />

Gmur, 1978). Organic Pb compounds tend to accumulate in lipids, and are taken up and<br />

accumulated in fish more readily than inorganic Pb compounds (Pattee and Pain, 2003).<br />

Given the complexities <strong>of</strong> metal uptake in natural systems, a model incorporating some <strong>of</strong><br />

the factors mentioned above is desirable. The <strong>EPA</strong>’s Environmental Research Laboratory in<br />

Duluth, Minnesota developed a thermodynamic equilibrium model, MINTEQ that predicts<br />

aqueous speciation, adsorption, precipitation, and/or dissolution <strong>of</strong> solids <strong>for</strong> a defined set <strong>of</strong><br />

environmental conditions (MacDonald et al., 2002; Playle, 2004). Although not specifically<br />

AX7-149


designed to model uptake, MINTEQ provides an indication <strong>of</strong> what <strong>for</strong>ms <strong>of</strong> the metal are likely<br />

to be encountered by aquatic organisms by estimating the <strong>for</strong>mation <strong>of</strong> metal ions, complexation<br />

<strong>of</strong> metals, and the general bioavailability <strong>of</strong> metals from environmental parameters. More<br />

recently, a mechanistic model centered on biodynamics has been proposed by Luoma and<br />

Rainbow (2005) as a method <strong>of</strong> tying together geochemical influences, biological differences,<br />

and differences among metals to model metal bioaccumulation. The biodynamic model would<br />

be useful in determining the potential adverse effects on aquatic biota, which species are most<br />

useful as indicators <strong>of</strong> metal effects, and how ecosystems may change when contaminated by<br />

metals. Two prominent models examine trace metal bioavailability and its link to effects<br />

(Hassler et al., 2004). These include the free ion activity model (FIAM) and the biotic ligand<br />

model (BLM). Specific in<strong>for</strong>mation on these models, including their limitations, is provided in<br />

Section AX7.2.1.3. These models are useful <strong>for</strong> advancing our understanding <strong>of</strong> how metal<br />

uptake occurs in aquatic organisms and how uptake and toxic effects are linked.<br />

Bioconcentration Factors (BCF)<br />

BCFs <strong>for</strong> Pb are reported <strong>for</strong> various aquatic plants in Table AX7-2.3.1. The green alga<br />

Cladophora glomerata is reported as having the highest BCF (Keeney et al., 1976). Duckweed<br />

(Lemna minor) exhibited high BCF values ranging from 840 to 3560 depending on the method <strong>of</strong><br />

measurement (Rahmani and Sternberg, 1999). Duckweed that was either previously exposed or<br />

not exposed to Pb was exposed to a single dose <strong>of</strong> Pb-nitrate at 5000 µg/L <strong>for</strong> 21 days.<br />

Duckweed that was previously exposed to Pb removed 70 to 80% <strong>of</strong> the Pb from the water, while<br />

the previously unexposed duckweed removed 85 to 90%. Both plant groups were effective at<br />

removing Pb from the water at sublethal levels.<br />

BCFs <strong>for</strong> Pb are reported <strong>for</strong> various invertebrates in Table AX7-2.3.2. BCFs <strong>for</strong><br />

freshwater snails were 738 <strong>for</strong> a 28-day exposure (Spehar et al., 1978) and 1,700 <strong>for</strong> a 120-day<br />

exposure (Borgmann et al., 1978). Other reported values <strong>for</strong> invertebrates included a BCF <strong>of</strong><br />

1930 <strong>for</strong> the scud during a 4-day exposure (MacLean et al., 1996), and BCFs <strong>of</strong> 499 and 1120 <strong>for</strong><br />

the caddis fly and stonefly, respectively, in 28-day exposures (Spehar et al., 1978). In a 28-day<br />

exposure, midge larvae were reported with a BCF <strong>of</strong> 3670 (Timmermans et al., 1992).<br />

AX7-150


Table AX7-2.3.1. Bioconcentration Factors <strong>for</strong> Aquatic Plants<br />

BCF Species Test Conditions Reference<br />

840 to 2700<br />

(measured digestion)<br />

1150 to 3560<br />

(measured solution)<br />

Duckweed<br />

(Lemna minor)<br />

16,000 to 20,000 Alga (Cladophora<br />

glomerata)<br />

AX7-151<br />

21 days, Pb-nitrate Rahmani and Sternberg<br />

(1999)<br />

Duckweed 21 days, Pb-nitrate Rahmani and Sternberg<br />

(1999)<br />

not specified Keeney et al. (1976)<br />

Table AX7-2.3.2. Bioconcentration Factors <strong>for</strong> Aquatic Invertebrates<br />

BCF Species Test Conditions Reference<br />

738 Snail (Physa integra) 28 days, Pb-nitrate Spehar et al. (1978)<br />

1700 Snail (Lymnaea palustris) 120 days, Pb-nitrate Borgmann et al. (1978)<br />

499 Caddis fly (Brachycentrus sp.) 28 days, Pb-nitrate Spehar et al. (1978)<br />

1120 Stonefly (Pteronarcys dorsata) 28 days, Pb-nitrate Spehar et al. (1978)<br />

1930 Scud (Hyalella azteca) 4 days, Pb-chloride MacLean et al. (1996)<br />

3670 Midge larvae (Chironomus riparius) 28 days Timmermans et al. (1992)<br />

BCFs <strong>for</strong> freshwater fish were 42 and 45 <strong>for</strong> brook trout and bluegill, respectively<br />

(Holcombe et al., 1976; Atchison et al., 1977). Although no BCFs have been reported <strong>for</strong><br />

amphibians, Pb-nitrate was reported to accumulate mainly in the ventral skin and in the kidneys<br />

<strong>of</strong> frogs (Vogiatzis and Loumbourdis, 1999).<br />

Bioconcentration factors and bioaccumulation factors (BAFs) are not necessarily the best<br />

predictors <strong>of</strong> tissue concentration levels given exposure concentration levels (Kapustka et al.,<br />

2004). The role <strong>of</strong> homeostatic mechanisms is a major consideration in tissue concentrations<br />

found in exposed biota. Similarly, measuring BCFs and BAFs in organisms may not accurately<br />

reflect how metals are treated within the organisms (e.g., partitioning to specific organelles,


sequestering to organ tissues). There<strong>for</strong>e, they are not recommended <strong>for</strong> use in conducting metal<br />

risk assessments (Kapustka et al., 2004).<br />

AX7.2.3.2 Resistance Mechanisms<br />

Detoxification Mechanisms<br />

Detoxification includes the biological processes by which the toxic qualities, or the<br />

probability and/or severity <strong>of</strong> harmful effects, <strong>of</strong> a poison or toxin are reduced by the organism.<br />

In the case <strong>of</strong> heavy metals, this process frequently involves the sequestration <strong>of</strong> the metal,<br />

rendering it metabolically inactive. Recent research into heavy metal detoxification in aquatic<br />

biota has focused on several physiological and biochemical mechanisms <strong>for</strong> detoxifying Pb.<br />

This section examines these mechanisms and the ability <strong>of</strong> plants, protists, invertebrates, and fish<br />

to mitigate Pb toxicity.<br />

Plants and Protists<br />

Deng et al. (2004) studied the uptake and translocation <strong>of</strong> Pb in wetland plant species<br />

surviving in contaminated sites. They found that all plants tended to sequester significantly<br />

larger amounts <strong>of</strong> Pb in their roots than in their shoots. Deng et al. (2004) calculated a<br />

translocation factor (TF), the amount <strong>of</strong> Pb found in the shoots divided by the amount <strong>of</strong> Pb<br />

found in the root system, and found that TFs ranged from 0.02 to 0.80. Concentrations <strong>of</strong> Pb in<br />

shoots were maintained at low levels and varied within a narrow range. Deng et al. (2004)<br />

observed that plants grown in Pb-contaminated sites usually contained higher concentrations<br />

than the 27 mg/kg toxicity threshold established <strong>for</strong> plants by Beckett and Davis (1977). Some<br />

<strong>of</strong> the wetland plants examined by Deng et al. (2004) also accumulated high concentrations <strong>of</strong><br />

metals in shoot tissues; however, these metals were assumed to be detoxified (metabolically<br />

unavailable), as no toxic response to these elevated concentrations was observed. Deng et al.<br />

(2004) suggested that this ability is likely related to discrete internal metal detoxification<br />

tolerance mechanisms.<br />

Phytochelatins are thiol-containing intracellular metal-binding polypeptides that are<br />

produced by plants and protists in response to excessive uptake <strong>of</strong> heavy metals (Zenk, 1996).<br />

Phytochelatins are synthesized by the enzyme phytochelatin synthase that is activated by the<br />

presence <strong>of</strong> metal ions and uses glutathione as a substrate. When phytochelatins are synthesized<br />

AX7-152


in sufficient amounts to chelate the metal ion, the enzyme is deactivated (Morelli and Scarano,<br />

2001).<br />

Morelli and Scarano (2001) studied phytochelatin synthesis and stability in the marine<br />

diatom Phaeodactylum tricornutum in the presence <strong>of</strong> Pb. They found that when metal exposure<br />

was alleviated, significant cellular Pb-phytochelatin complex content was lost. Their findings<br />

support a hypothesis <strong>of</strong> vacuolarization proposed <strong>for</strong> higher plants (Zenk, 1996), in which metal-<br />

phytochelatin complexes are actively transported from the cytosol to the vacuole, where they<br />

undergo rapid turnover. Zenk (1996) suggested that the complex dissociates, and the metal-free<br />

peptide is subsequently degraded. Morelli and Scarano (2001) proposed concomitant occurrence<br />

<strong>of</strong> phytochelatin synthesis and release during metal exposure, as a coincident detoxification<br />

mechanism in P. tricornutum.<br />

Aquatic Invertebrates<br />

Like plants and protists, aquatic animals detoxify Pb by preventing it from being<br />

metabolically available, though their mechanisms <strong>for</strong> doing so vary. Invertebrates use<br />

lysosomal-vacuolar systems to sequester and process Pb within glandular cells (Giamberini and<br />

Pihan, 1996). They also accumulate Pb as deposits on and within skeletal tissue (Knowlton<br />

et al., 1983; Anderson et al., 1997; Boisson et al., 2002), and some can efficiently excrete Pb<br />

(Vogt and Quinitio, 1994; Prasuna et al., 1996).<br />

Boisson et al. (2002) used radiotracers to evaluate the transfer <strong>of</strong> Pb into the food pathway<br />

<strong>of</strong> the starfish Asterias rubens as well as its distribution and retention in various body<br />

compartments. Boisson et al. (2002) monitored Pb elimination after a single feeding <strong>of</strong> Pbcontaminated<br />

molluscs and found that Pb was sequestered and retained in the skeleton <strong>of</strong> the<br />

starfish, preventing it from being metabolically available in other tissues. Elimination (as<br />

percent retention in the skeleton) was found to follow an exponential time course. Elimination<br />

was rapid at first, but slowed after 1 week, and eventually stabilized, implying an infinite<br />

biological half-life <strong>for</strong> firmly bound Pb. Results <strong>of</strong> radiotracer tracking suggest that Pb migrates<br />

within the body wall from the organic matrix to the calcified skeleton. From there, the metal is<br />

either absorbed directly or adsorbed on newly produced ossicles (small calcareous skeletal<br />

structures), where it is efficiently retained as mineral deposition and is not metabolically active<br />

(Boisson et al., 2002).<br />

AX7-153


AbdAllah and Moustafa (2002) studied the Pb storage capability <strong>of</strong> organs in the marine<br />

snail Nerita saxtilis. Enlarged electron-dense vesicles and many granules were observed in<br />

digestive cells <strong>of</strong> these snails and are suggested to be the site <strong>of</strong> storage <strong>of</strong> detoxified metals.<br />

N. saxtilis were found to be capable <strong>of</strong> concentrating Pb up to 50 times that <strong>of</strong> surrounding<br />

marine water without exhibiting signs <strong>of</strong> histopathologic changes. This ability has been<br />

attributed to chelation with various biochemical compounds, such as thionine (<strong>for</strong>ming<br />

metallothionine) (Rainbow, 1996), or complexation with carbonate, <strong>for</strong>ming lip<strong>of</strong>uchsin<br />

(AbdAllah and Moustafa, 2002). Granules observed in lysosomal residual bodies were presumed<br />

to be the result <strong>of</strong> Pb accumulation. The presence <strong>of</strong> large vacuoles and residual bodies were<br />

indicative <strong>of</strong> the fragmentation phase <strong>of</strong> digestion, suggesting that Pb was also processed<br />

chemically in the digestive cells.<br />

The podocyte cells <strong>of</strong> the pericardial gland <strong>of</strong> bivalves are involved in the ultrafiltration <strong>of</strong><br />

the hemolymph (Giamberini and Pihan, 1996). A microanalytical study <strong>of</strong> the podocytes in<br />

Dreissena polymorpha exposed to Pb revealed lysosomal-vacuolar storage/processing similar to<br />

that in the digestive cells <strong>of</strong> Nerita saxtilis. The lysosome is thought to be the target organelle<br />

<strong>for</strong> trace metal accumulation in various organs <strong>of</strong> bivalves (Giamberini and Pihan, 1996).<br />

Epithelial secretion is the principal detoxification mechanism <strong>of</strong> the tiger prawn Penaeus<br />

monodon. Vogt and Quinitio (1994) found that Pb granules tended to accumulate in the<br />

epithelial cells <strong>of</strong> the antennal gland (the organ <strong>of</strong> excretion) <strong>of</strong> juveniles exposed <strong>for</strong> 5 and<br />

10 days to waterborne Pb. The metal is deposited in vacuoles belonging to the lysosomal<br />

system. Continued deposition leads to the <strong>for</strong>mation <strong>of</strong> electron-dense granules. Mature<br />

granules are released from the cells by apocrine secretion into the lumen <strong>of</strong> the gland, and<br />

presumably excreted through the nephridopore (i.e., the opening <strong>of</strong> the antennal gland).<br />

Apocrine secretion is predominant, so that as granules <strong>for</strong>m, they are kept at low levels.<br />

Excretion was also found to be a primary and efficient detoxification mechanism in the shrimp<br />

Chrissia halyi (Prasuna et al., 1996).<br />

Crayfish exposed to Pb have been shown to concentrate the metal in their exoskeleton and<br />

exuvia through adsorption processes. More than 80% <strong>of</strong> Pb found in exposed crayfish has been<br />

found in exoskeletons (Knowlton et al., 1983; Anderson et al., 1997). Following exposure,<br />

clearance is most dramatic from the exoskeleton. The result <strong>of</strong> a 3-week Pb-clearance study with<br />

red swamp crayfish Procambarus clarkia, following a 7-week exposure to 150 µg Pb/L, showed<br />

AX7-154


an 87% clearance from the exoskeleton due, in part, to molting. Other organs or tissues that take<br />

up significant amounts <strong>of</strong> Pb include the gills, hepatopancreas, muscle, and hemolymph, in<br />

decreasing order. These parts cleared >50% <strong>of</strong> accumulated Pb over the 3-week clearance<br />

period, with the exception <strong>of</strong> the hepatopancreas. The hepatopancreas is the organ <strong>of</strong> metal<br />

storage and detoxification, although the molecular mechanisms <strong>of</strong> metal balance in crayfish have<br />

yet to be extensively investigated (Anderson et al., 1997).<br />

Fish<br />

Most fish use mucus as a first line <strong>of</strong> defense against heavy metals (Coello and Khan,<br />

1996). In fish, some epithelia are covered with extracellular mucus secreted from specialized<br />

cells. Mucus contains glycoproteins, and composition varies among species. Mucosal<br />

glycoproteins chelate Pb, and settle, removing the metal from the water column. Fish may<br />

secrete large amounts <strong>of</strong> mucus when they come into contact with potential chemical and<br />

biochemical threats. Coello and Khan (1996) investigated the role <strong>of</strong> externally added fish<br />

mucus and scales in accumulating Pb from water, and the relationship <strong>of</strong> these with the toxicity<br />

<strong>of</strong> Pb in fingerlings <strong>of</strong> green sunfish, goldfish and largemouth bass. The authors compared trials<br />

in which fish scales from black sea bass (Centropristis striata) and flounder (Pseudopleuronectes<br />

americanus) and mucus from largemouth bass were added to green sunfish, goldfish, and<br />

largemouth bass test systems and to reference test systems. On exposure to Pb, fish immediately<br />

started secreting mucus from epidermal cells in various parts <strong>of</strong> the body. Metallic Pb stimulated<br />

filamentous secretion, mostly from the ventrolateral areas <strong>of</strong> the gills, while Pb-nitrate stimulated<br />

diffuse molecular mucus secretion from all over the body. The addition <strong>of</strong> largemouth bass<br />

mucus significantly increased the LT50 (the time to kill 50%) <strong>for</strong> green sunfish and goldfish<br />

exposed to 250 mg/L <strong>of</strong> Pb-nitrate. In contrast, Tao et al. (2000) found that mucus reduced the<br />

overall bioavailability <strong>of</strong> Pb to fish but that the reduction was insignificant. Coello and Khan<br />

(1996) found that scales were more significant in reducing LT50 than mucous. Fish scales can<br />

accumulate high concentrations <strong>of</strong> metals, including Pb, through chelation with keratin. Scales<br />

were shown to buffer the pH <strong>of</strong> Pb-nitrate in solution and remove Pb from water after which they<br />

settled out <strong>of</strong> the water column. Addition <strong>of</strong> scales to test water made all species (green sunfish,<br />

goldfish, and largemouth bass) more tolerant <strong>of</strong> Pb.<br />

AX7-155


Summary <strong>of</strong> Detoxifiction Processes<br />

Mechanisms <strong>of</strong> detoxification vary among aquatic biota and include processes such as<br />

translocation, excretion, chelation, adsorption, vacuolar storage, and deposition. <strong>Lead</strong><br />

detoxification has not been studied extensively in aquatic organisms, but existing results indicate<br />

the following:<br />

• Protists and plants produce intracellular polypeptides that <strong>for</strong>m complexes with Pb (Zenk,<br />

1996; Morelli and Scarano, 2001).<br />

• Macrophytes and wetland plants that thrive in Pb-contaminated regions have developed<br />

translocation strategies <strong>for</strong> tolerance and detoxification (Knowlton et al., 1983; Deng et al.,<br />

2004).<br />

• Some starfish (asteroids) sequester the metal via mineral deposition into the exoskeleton<br />

(Boisson et al., 2002).<br />

• Species <strong>of</strong> mollusc employ lysosomal-vacuolar systems that store and chemically process Pb<br />

in the cells <strong>of</strong> their digestive and pericardial glands (Giamberini and Pihan, 1996; AbdAllah<br />

and Moustafa, 2002).<br />

• Decapods can efficiently excrete Pb (Vogt and Quinitio, 1994; Giamberini and Pihan, 1996)<br />

and sequester metal through adsorption to the exoskeleton (Knowlton et al., 1983).<br />

• Fish scales and mucous chelate Pb in the water column, and potentially reduce visceral<br />

exposure.<br />

Avoidance Response<br />

Avoidance is the evasion <strong>of</strong> a perceived threat. Recent research into heavy metal<br />

avoidance in aquatic organisms has looked at dose-response relationships as well as the effects <strong>of</strong><br />

coincident environmental factors. Preference/avoidance response to Pb has not been extensively<br />

studied in aquatic organisms. In particular, data <strong>for</strong> aquatic invertebrates is lacking.<br />

Using recent literature, this section examines preference-avoidance responses <strong>of</strong><br />

invertebrates and fish to Pb and some other environmental gradients.<br />

Aquatic Invertebrates<br />

Only one study was identified on avoidance response in aquatic invertebrates. Lefcort<br />

et al. (2004) studied the avoidance behavior <strong>of</strong> the aquatic pulmonate snail Physella columbiana<br />

from a pond that had been polluted with heavy metals <strong>for</strong> over 120 years. In a Y-maze test, first<br />

generation P. columbiana from the contaminated site avoided Pb at 9283 µg/L (p < 0.05) and<br />

AX7-156


moved toward Pb at 6255 µg/L (p < 0.05). It is thought that attraction to Pb at certain elevated<br />

concentrations is related to Pb neuron-stimulating properties (Lefcort et al., 2004). These results<br />

are consistent with those from similar studies. Control snails from reference sites, and first and<br />

second-generation snails from contaminated sites were capable <strong>of</strong> detecting and avoiding heavy<br />

metals, although the first generation was better than the second generation, and the second was<br />

better than the controls at doing so. This suggests that detection and avoidance <strong>of</strong> Pb is both<br />

genetic and environmentally based <strong>for</strong> P. columbiana. Lefcort et al. (2004) observed heightened<br />

sensitivity to, and avoidance <strong>of</strong>, heavy metals by the snails when metals where present in<br />

combination.<br />

Aquatic Vertebrates<br />

Steele et al. (1989) studied the preference-avoidance response <strong>of</strong> bullfrog (Rana<br />

catesbeiana) to plumes <strong>of</strong> Pb-contaminated water following 144-h exposure to 0 to 1000 µg<br />

Pb/L. In this laboratory experiment, tadpoles were exposed to an influx <strong>of</strong> 1000 µg Pb/L at five<br />

different infusion rates (i.e., volumes per unit time into the test system). Experiments were<br />

videotaped and location data from the tank were used to assess response. No significant<br />

differences were seen in preference-avoidance responses to Pb in either nonexposed or<br />

previously exposed animals. In a similar subsequent study, Steele et al. (1991) studied<br />

preference-avoidance response to Pb in American toad (Bufo americanus) using the same<br />

exposure range (0 to 1000 µg Pb/L). B. americanus did not significantly avoid Pb, and<br />

behavioral stress responses were not observed. The results do not indicate whether the tadpoles<br />

were capable <strong>of</strong> perceiving the contaminant. Lack <strong>of</strong> avoidance may indicate insufficient<br />

perception or the lack <strong>of</strong> physiological stress (Steele et al., 1991).<br />

The olfactory system in fish is involved in their <strong>for</strong>ming avoidance response to heavy<br />

metals (Brown et al., 1982; Svecevičius, 1991). It is generally thought that behavioral avoidance<br />

<strong>of</strong> contaminants may be a cause <strong>of</strong> reduced fish populations in some water bodies, because <strong>of</strong><br />

disturbances in migration and distribution patterns (Svecevičius, 2001). Un<strong>for</strong>tunately,<br />

avoidance <strong>of</strong> Pb by fish has not been studied as extensively as <strong>for</strong> other heavy metals<br />

(Woodward et al., 1995).<br />

Woodward et al. (1995) studied metal mixture avoidance response in brown trout<br />

(Salmo trutta), as well as the added effects <strong>of</strong> acidification. A 1-fold (1Η) mixture contained<br />

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1.1 µg/L Cd, 12 µg/L Cu, 55 µg/L Zn, and 3.2 µg/L Pb (all metals were in the <strong>for</strong>m <strong>of</strong> chlorides).<br />

Avoidance was quantified as time spent in test water, trip time to test water, and number <strong>of</strong> trips.<br />

Brown trout avoided the 1Η mixture as well as the 0.5Η, 2Η, 4Η, and 10Η mixtures, but not the<br />

0.1Η mixture. Reduced avoidance was observed at higher concentrations (4Η and 10Η). The<br />

authors proposed that the reduced avoidance response was due to impaired perception due to<br />

injury. These responses are typical <strong>of</strong> other fish species to individual metals <strong>of</strong> similar<br />

concentrations (Woodward et al., 1995). This study does not conclusively indicate which <strong>of</strong> the<br />

metals in the mixture may be causing the avoidance response. However, given the neurotoxic<br />

effects <strong>of</strong> Pb, impaired perception is a likely response <strong>of</strong> Pb-exposed fish.<br />

When test water was reduced in pH from 8 to 7, 6 to 5, brown trout avoidance increased,<br />

but with no significant difference between metal treatments and controls. However, in the 1Η<br />

metal mixture treatment, brown trout made fewer trips into the test water chamber at the lower<br />

pHs (Woodward et al., 1995). This response may be related to an increased abundance <strong>of</strong> Pb<br />

cations at lower pH values in the test system.<br />

Scherer and McNicol (1998) investigated the preference-avoidance responses <strong>of</strong> lake<br />

whitefish (Coregonus clupea<strong>for</strong>mis) to overlapping gradients <strong>of</strong> light and Pb. Whitefish were<br />

found to prefer shade in untreated water. <strong>Lead</strong> concentrations under illumination ranged from<br />

0 to 1000 µg/L, and from 0 to 54,000 µg/L in the shade. Under uni<strong>for</strong>m illumination, Pb was<br />

avoided at concentrations above 10 µg/L, but avoidance behavior lacked a dose-dependent<br />

increase over concentrations ranging from 10 to 1000 µg Pb/L. Avoidance in shaded areas was<br />

strongly suppressed, and whitefish only avoided Pb at concentrations at or above 32,000 µg/L.<br />

Summary <strong>of</strong> Avoidance Response<br />

In summary, <strong>of</strong> those aquatic organisms studied, some are quite adept at avoiding Pb in<br />

aquatic systems, while others seem incapable <strong>of</strong> detecting its presence. Snails have been shown<br />

to be sensitive to Pb and to avoid it at high concentrations. Conversely, anuran (frog and toad)<br />

species lack an avoidance response to the metal. Fish avoidance <strong>of</strong> many chemical toxicants has<br />

been well established, and it is a dominant sublethal response in polluted waters (Svecevičius,<br />

2001). However, no studies have been located specifically examining avoidance behavior <strong>for</strong> Pb<br />

in fish. Environmental gradients, such as light and pH, can alter preference-avoidance responses.<br />

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AX7.2.3.3 Physiological Effects <strong>of</strong> <strong>Lead</strong><br />

This section presents a review <strong>of</strong> the physiological effects and functional growth<br />

responses associated with the exposure <strong>of</strong> aquatic biota to Pb. Physiological effects <strong>of</strong> Pb on<br />

aquatic biota can occur at the biochemical, cellular, and tissue levels <strong>of</strong> organization and include<br />

inhibition <strong>of</strong> heme <strong>for</strong>mation, adverse effects to blood chemistry, and decreases in enzyme<br />

levels. Functional growth responses resulting from Pb exposure include changes in growth<br />

patterns, gill binding affinities, and absorption rates.<br />

Biochemical Effects<br />

<strong>Lead</strong> was observed to have a gender-selective effect on brain endocannabinoid (eCB)<br />

(e.g., 2-arachidonylglycerol [2-AG] and N-arachidonylethanolamine [AEA]) levels in fathead<br />

minnow Pimephales promelas (Rademacher et al., 2005). Cannabinoids, such as eCB, influence<br />

locomotor activity in organisms. Increased levels <strong>of</strong> cannabinoids have been shown to stimulate<br />

locomotor activity and decreased levels slow locomotor activity (Sañudo-Peña et al., 2000).<br />

Male and female fathead minnows were exposed to 0 and 1000 µg/L <strong>of</strong> Pb. Female minnows in<br />

the control group contained significantly higher levels <strong>of</strong> AEA and 2-AG compared to males.<br />

At a concentration <strong>of</strong> 1000 µg Pb/L, this pattern reversed, with males showing significantly<br />

higher levels <strong>of</strong> AEA in the brain than females (Rademacher et al., 2005). After 14-days<br />

exposure to the 1000 µg Pb/L treatment, significantly higher levels <strong>of</strong> 2-AG were found in male<br />

fathead minnows, but no effect on 2-AG levels in females was observed (Rademacher et al.,<br />

2005).<br />

<strong>Lead</strong> acetate slightly inhibited 7-ethoxyresorufin-o-deethylase (7-EROD) activity in<br />

Gammarus pulex exposed <strong>for</strong> up to 96 h to a single toxicant concentration (EC50) (Kutlu and<br />

Susuz, 2004). The exact concentration used in the study was not reported. The EROD enzyme<br />

is required to catalyze the conjugation and detoxification <strong>of</strong> toxic molecules and has been<br />

proposed as a biomarker <strong>for</strong> contaminant exposure. The authors believe more detailed studies<br />

are required to confirm EROD as a biomarker <strong>for</strong> Pb exposure. The enzyme group alanine<br />

transferases (ALT) has been suggested as a bioindicator/biomarker <strong>of</strong> Pb stress (Blasco and<br />

Puppo, 1999). A negative correlation was observed between Pb accumulation and ALT<br />

concentrations in the gills and s<strong>of</strong>t body <strong>of</strong> Ruditapes philippinarum exposed to 350 to 700 µg/L<br />

<strong>of</strong> Pb <strong>for</strong> 7 days (Blasco and Puppo, 1999).<br />

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Studies have identified ALAD in fish and amphibians as a useful indicator <strong>of</strong> Pb exposure<br />

(Gill et al., 1991; Nakagawa et al., 1995a,b). ALAD catalyzes the <strong>for</strong>mation <strong>of</strong> hemoglobin and<br />

early steps in the synthesis <strong>of</strong> protoporphyrin (Gill et al., 1991; Nakagawa et al., 1995b). The<br />

absence <strong>of</strong> an inhibitory effect on this enzyme following exposure to cadmium, copper, zinc, and<br />

mercury suggests that this enzyme reacts specifically to Pb (Johansson-Sjöbeck and Larsson,<br />

1979; Gill et al., 1991). A 0% decrease in ALAD activity was reported in common carp<br />

(Cyprinus carpio) exposed to a Pb concentration <strong>of</strong> 10 µg/L <strong>for</strong> 20 days (Nakagawa et al.,<br />

1995b). The recovery <strong>of</strong> ALAD activity after exposure to Pb has also been examined in carp<br />

(Nakagawa et al., 1995a). After 2-week exposure to 200 µg Pb/L, ALAD activity decreased to<br />

approximately 25% <strong>of</strong> value reported <strong>for</strong> controls (Nakagawa et al., 1995a). Fish removed from<br />

the test concentration after 2 weeks and placed in a Pb-free environment recovered slightly, but<br />

ALAD activity was only 50% <strong>of</strong> the controls even after 4 weeks (Nakagawa et al., 1995a).<br />

Vogiatzis and Loumbourdis (1999) exposed the frog (Rana ridibunda) to a Pb concentration <strong>of</strong><br />

14,000 µg/L over 30 days and a 90% decrease in ALAD activity was observed in the frogs.<br />

Blood Chemistry<br />

Numerous studies have examined the effects <strong>of</strong> Pb exposure on blood chemistry in aquatic<br />

biota. These studies have primarily used fish in acute and chronic exposures to Pb<br />

concentrations ranging from 100 to 10,000 µg/L. Decreased erythrocyte, hemoglobin, and<br />

hemocrit levels were observed in rosy barb (Barbus puntius) during an 8-week exposure to<br />

126 µg/L <strong>of</strong> Pb-nitrate (Gill et al., 1991).<br />

No difference was found in red blood cell counts and blood hemoglobin in yellow eels<br />

(Anguilla anguilla) exposed to 0 and 300 µg/L <strong>of</strong> Pb <strong>for</strong> 30 days (Santos and Hall, 1990). The<br />

number <strong>of</strong> white blood cells, in the <strong>for</strong>m <strong>of</strong> lymphocytes, increased in the exposed eels. The<br />

authors concluded this demonstrates the lasting action <strong>of</strong> Pb as a toxicant on the immune system<br />

(Santos and Hall, 1990). Significant decreases in red blood cell counts and volume was reported<br />

in blue tilapia (Oreochromis aureus) exposed to Pb-chloride at a concentration <strong>of</strong> 10,000 µg/L<br />

<strong>for</strong> 1 week (Allen, 1993).<br />

Blood components, such as plasma glucose, total plasma protein, and total plasma<br />

cholesterol, were unaffected in yellow eels exposed to 300 µg/L <strong>of</strong> Pb <strong>for</strong> 30 days (Santos and<br />

Hall, 1990). Effects on plasma chemistry were observed in Oreochromis mossambicus exposed<br />

AX7-160


to 0, 18,000, 24,000, and 33,000 µg/L <strong>of</strong> Pb (Ruparelia et al., 1989). Significant decreases in<br />

plasma glucose (hypoglycemic levels) were reported at concentrations <strong>of</strong> 24,000 and 33,000 Φg<br />

Pb/L after 14 and 21 days <strong>of</strong> exposure, and at 18,000 µg Pb/L after 21 days <strong>of</strong> exposure<br />

(Ruparelia et al., 1989). Plasma cholesterol levels dropped significantly in comparison to<br />

controls after 14 days <strong>of</strong> exposure to 33,000 µg Pb/L and in all test concentrations after 21 days<br />

<strong>of</strong> exposure (Ruparelia et al., 1989). Similarly, concentrations <strong>of</strong> blood serum protein, albumin,<br />

and globulin were identified as bioindicators <strong>of</strong> Pb stress in carp (Cyprinus carpio) exposed to<br />

Pb-nitrates at concentrations <strong>of</strong> 800 and 8000 µg Pb/L (Gopal et al., 1997).<br />

Tissues<br />

In fish, the gills serve as an active site <strong>for</strong> ion uptake. Recent studies have examined the<br />

competition between cations <strong>for</strong> binding sites at the fish gill (e.g., Ca 2+ , Mg 2+ , Na + , H + , Pb 2+ )<br />

(MacDonald et al., 2002; Rogers and Wood, 2003, 2004). Studies suggest that Pb 2+ is an<br />

antagonist <strong>of</strong> Ca 2+ uptake (Rogers and Wood, 2003, 2004). MacDonald et al. (2002) proposed a<br />

gill-Pb binding model that assumes Pb 2+ has a ∃100 times greater affinity <strong>for</strong> binding sites at the<br />

fish gill than other cations. More toxicity studies are required to quantify critical Pb burdens that<br />

could be used as indicators <strong>of</strong> Pb toxicity (Niyogi and Wood, 2003).<br />

Growth Responses<br />

A negative linear relationship was observed in the marine gastropod abalone (Haliotis)<br />

between shell length and muscle Pb concentrations (Arai et al., 2002). Abalones were collected<br />

from two sites along the Japanese coast. Haliotis discus hannai were collected from along the<br />

coast at Onagawa; Haliotis discus were collected from along the coast at Amatsu Kominato. The<br />

authors did not report significant differences between the two sampling sites. From samples<br />

collected at Onagawa, Pb concentrations <strong>of</strong> 0.03 and 0.01 µg/g were associated with abalone<br />

shell lengths <strong>of</strong> 7.7 cm (3 years old) and 12.3 cm (6 years old), respectively. From samples<br />

collected at Amatsu Kominato, Pb concentrations <strong>of</strong> 0.09 and 0.01 µg/g were associated with<br />

abalone shell lengths <strong>of</strong> 3.9 cm (0 years old) and 15.3 cm (8 years old), respectively (Arai et al.,<br />

2002). The authors theorized that young abalones, experiencing rapid growth, do not<br />

discriminate between the uptake <strong>of</strong> essential and nonessential metals. However, as abalones<br />

grow larger and their rate <strong>of</strong> growth decreases, they increasingly favor the uptake <strong>of</strong> essential<br />

AX7-161


metals over nonessential metals. This is demonstrated by the relatively consistent concentrations<br />

<strong>of</strong> Cu, Mn, and Zn that were reported <strong>for</strong> the abalone samples (Arai et al., 2002).<br />

Other Physiological Effects<br />

Increased levels <strong>of</strong> Pb in water were found to increase fish production <strong>of</strong> mucus: excess<br />

mucus coagulates were observed over the entire body <strong>of</strong> fishes. Buildup was particularly high<br />

around the gills, and in the worst cases, interfered with respiration and resulted in death by<br />

anoxia (Aronson, 1971; National Research Council <strong>of</strong> Canada., 1973).<br />

AX7.2.3.4 Factors That Modify Organism Response to <strong>Lead</strong><br />

A great deal <strong>of</strong> research has been undertaken recently to better understand the factors that<br />

modify aquatic organism response to metals including lead. A discussion <strong>of</strong> research on the<br />

many factors that can modify aquatic organism response to Pb is provided in this section.<br />

Influence <strong>of</strong> Organism Age and Size on <strong>Lead</strong> Uptake and Response<br />

It is generally accepted that Pb accumulation in living organisms is controlled, in part, by<br />

metabolic rates (Farkas et al., 2003). Metabolic rates are, in-turn, controlled by the physiological<br />

conditions <strong>of</strong> an organism, including such factors as size, age, point in reproductive cycle,<br />

nutrition, and overall health. Of these physiological conditions, size and age are the most<br />

commonly investigated in relation to heavy metal uptake. This section reviews recent research<br />

focusing on relationships between body size, age, and Pb accumulation in aquatic invertebrates<br />

and fish.<br />

Invertebrates<br />

MacLean et al. (1996) investigated bioaccumulation kinetics and toxicity <strong>of</strong> Pb in the<br />

amphipod Hyalella azteca. Their results indicated that body size did not greatly influence Pb<br />

accumulation in H. azteca exposed to 50 or 100 µg/L <strong>of</strong> PbCl2 <strong>for</strong> 4 days. Canli and Furness<br />

(1993) found similar results in the Norway lobster Nephrops norvegicus exposed to 100 µg/L <strong>of</strong><br />

Pb(NO3)2 <strong>for</strong> 30 days. No significant sex- or size-related differences were found in<br />

concentrations <strong>of</strong> Pb in the tissue. The highest tissue burden was found in the carapaces (42%).<br />

Several studies have determined that Pb can bind to the exoskeleton <strong>of</strong> invertebrates and<br />

AX7-162


sometimes dominate the total Pb accumulated (Knowlton et al., 1983). This adsorption <strong>of</strong> Pb to<br />

the outer surface <strong>of</strong> invertebrates can result in strong negative relationships <strong>for</strong> whole-body Pb<br />

concentration as a function <strong>of</strong> body mass (i.e., concentrations decrease rapidly with increased<br />

body size and then stabilize) (MacLean et al., 1996).<br />

Drava et al. (2004) investigated Pb concentrations in the muscle <strong>of</strong> red shrimp Aristeus<br />

antennatus from the northwest Mediterranean. <strong>Lead</strong> concentrations ranged from 0.04 to<br />

0.31 µg/g dw. No significant relationships between size and Pb concentration in A. antennatus<br />

were found, and concentrations were not related to reproductive status.<br />

Arai et al. (2002) analyzed abalones (Haliotis) at various life stages from coastal regions<br />

<strong>of</strong> Japan. They investigated growth effects on the uptake and elimination <strong>of</strong> Pb. Results<br />

indicated a significant negative linear relationship between age, shell length and Pb<br />

concentrations in muscle tissue. The relationship was consistent despite habitat variations in<br />

Pb concentrations between the study sites, suggesting that Pb concentrations changed with<br />

growth in the muscle tissue <strong>of</strong> test specimens and implying that abalone can mitigate Pb<br />

exposure as they age.<br />

Fish<br />

Douben (1989) investigated the effects <strong>of</strong> body size and age on Pb body burden in the<br />

stone loach (Noemacheilus barbatulus L.). Fish were caught during two consecutive springs<br />

from three Derbyshire rivers. Results indicated that Pb burden increased slightly with age.<br />

Similarly, Köck et al. (1996) found that concentrations <strong>of</strong> Pb in the liver and kidneys <strong>of</strong> Arctic<br />

char (Salvelinus alpinus) taken from oligotrophic alpine lakes were positively correlated with<br />

age. It has been suggested that fish are not able to eliminate Pb completely, and that this leads to<br />

a stepwise accumulation from year to year (Köck et al., 1996). In contrast, Farkas et al. (2003)<br />

found a negative relationship between Pb concentrations and muscle and gill Pb concentrations<br />

in the freshwater fish Abramis brama. Fish were taken from a low-contaminated site and<br />

contained between 0.44 and 3.24 µg/g Pb dw. Negative correlations between metal<br />

concentration and fish size in low-contaminated waters likely results from variations in feeding<br />

rates associated with developmental stages. This hypothesis is consistent with the fact that in<br />

low-contaminated waters, feeding is the main route <strong>of</strong> uptake and feeding rates decrease with<br />

development in fish (Farkas et al., 2003).<br />

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In summary, relationships between age, size, and Pb body burden in aquatic invertebrates<br />

and fish are interspecifically variable and depend on many environment-related variables (e.g.,<br />

exposure) (Farkas et al., 2003).<br />

Genetics<br />

There are few studies documenting the effects <strong>of</strong> Pb on organismal and population<br />

genetics, although rapid advances in biotechnology have prompted recent research in this area<br />

(Beaty et al., 1998). There are two principal effects that sublethal exposure to a contaminant can<br />

have on the genetics <strong>of</strong> an organism and/or population: (1) a contaminant may influence<br />

selection by selecting <strong>for</strong> certain phenotypes that enable populations to better cope with the<br />

chemical; or (2) a contaminant can be genotoxic, meaning it can produce alterations in nucleic<br />

acids at sublethal exposure concentrations, resulting in changes in hereditary characteristics or<br />

DNA inactivation (Shugart, 1995). Laboratory studies have shown that exposure to Pb 2+ at<br />

10 mg/mL in blood produces chromosomal aberrations (i.e., deviations in the normal structure or<br />

number <strong>of</strong> chromosomes) in some organisms (Cestari et al., 2004). Effects <strong>of</strong> genotoxicity and<br />

toxin-induced selection do not preclude one another, and may act together on exposed<br />

populations. This section reviews Pb genotoxicity and the effects <strong>of</strong> Pb-induced selection in<br />

aquatic populations.<br />

Selection<br />

Evidence <strong>for</strong> genetic selection in the natural environment has been observed in some<br />

aquatic populations exposed to metals (Rand et al., 1995; Beaty et al., 1998; Duan et al., 2000;<br />

Kim et al., 2003). Because tolerant individuals have a selective advantage over vulnerable<br />

individuals in polluted environments, the frequency <strong>of</strong> tolerance genes will increase in exposed<br />

populations over time (Beaty et al., 1998). Several studies have shown that heavy metals can<br />

alter population gene pools in aquatic invertebrates. These changes have resulted in decreased<br />

genetic diversity and are thought to be a potential source <strong>of</strong> population instability (Duan et al.,<br />

2000; Kim et al., 2003).<br />

Kim et al. (2003) investigated genetic differences and population structuring in the<br />

gastropod Littorina brevicula from heavy-metal polluted and unpolluted environments.<br />

Organisms from polluted sites contained a mean <strong>of</strong> 1.76 µg Pb/g, while organisms from<br />

AX7-164


unpolluted sites contained 0.33 µg Pb/g. They found significant differences in haplotypes<br />

between the test groups and allelic diversity was significantly lower among L. brevicula from<br />

polluted regions. In contrast, Yap et al. (2004) per<strong>for</strong>med a similar experiment with the green-<br />

lipped mussel Perna viridis; they found that mussels from contaminated sites containing between<br />

4 and 10 µg Pb/g, as well as other heavy metals, exhibited a higher percentage <strong>of</strong> polymorphic<br />

loci and excess heterozygosity compared to those from uncontaminated sites. The higher level<br />

<strong>of</strong> genetic diversity was attributed to greater environmental heterogeneity (i.e., variation due to<br />

pollution gradients) in contaminated sites (Yap et al., 2004).<br />

Duan et al. (2000) investigated amphipod (Hyalella azteca) selective mortality and<br />

genetic structure following acute exposure to Pb (5.47 mg/L Pb(NO2)2) as well as exposure to<br />

other heavy metals. They found that genetic differentiation consistently increased among<br />

survivors from the original population, supporting the hypothesis that heavy metals, including<br />

Pb, have the potential to alter the gene pools <strong>of</strong> aquatic organisms.<br />

Genotoxicity<br />

<strong>Lead</strong> exposure in water (50 µg/L) over 4 weeks resulted in DNA strand breakage in the<br />

freshwater mussel Anodonta grandis (Black et al., 1996), although higher concentrations (up to<br />

5000 µg/L) did not result in significant breakage by the end <strong>of</strong> the study period. These results<br />

suggest that a threshold effect <strong>for</strong> DNA damage and repair exists, where DNA repair only occurs<br />

once a certain body exposure level has been reached. More recently, Cestari et al. (2004)<br />

observed similar results in neotropical fish (Hoplias malabaricus) that were fed Pb-contaminated<br />

food over 18, 41, and 64 days. <strong>Lead</strong> body burdens in H. malabaricus were approximately 21 µg<br />

Pb 2+ /g. Results indicated that exposure to Pb significantly increased the frequency <strong>of</strong><br />

chromosomal aberrations and DNA damage in kidney cell cultures, although when assessed at<br />

the end <strong>of</strong> the longer exposure periods, aberrations were less common.<br />

Environmental Biological Factors<br />

Environmental factors that are biological in origin can alter the availability, uptake and<br />

toxicity <strong>of</strong> Pb to aquatic organisms. These factors can be grouped into living and non-living<br />

constituents. For example, living organisms may sequester Pb from the water column, reducing<br />

the availability and toxicity <strong>of</strong> the metal in the water column to other biota, thus reducing<br />

AX7-165


potential toxic effects in other organisms. Non-living organic material (e.g., components <strong>of</strong><br />

sloughed-<strong>of</strong>f scales, mucus, carcasses, and other decomposing, humic material) can similarly<br />

combine with Pb from the water column, rendering it unavailable. This section will review the<br />

literature on biological environmental factors and their influence on the bioavailability, uptake,<br />

and toxicity <strong>of</strong> Pb.<br />

Van Hattum et al. (1996) studied the influence <strong>of</strong> abiotic variables, including DOC on Pb<br />

concentrations in freshwater isopods (Proasellus meridianus and Asellus aquaticus). They found<br />

that BCFs were significantly negatively correlated with DOC concentrations. Thus, as DOC<br />

concentrations increased, BCFs decreased in P. meridianus and A. aquaticus, indicating that<br />

DOC acts to inhibit the availability <strong>of</strong> Pb to these isopods.<br />

Kruatrachue et al. (2002) investigated the combined effects <strong>of</strong> Pb and humic acid on total<br />

chlorophyll content, growth rate, multiplication rate, and Pb uptake <strong>of</strong> common duckweed.<br />

When humic acid was added to the Pb-nitrate test solutions (50, 100, and 200 mg Pb(NO3)2/ L),<br />

toxicity <strong>of</strong> Pb to duckweed was decreased. The addition <strong>of</strong> humic acid to the Pb-nitrate solution<br />

increased the pH. The authors suggested that there was a proton dissociation from the carboxyl<br />

group in the humic acid that complexed with Pb, resulting in a decrease in free Pb ions available<br />

to the plant.<br />

Schwartz et al. (2004) collected natural organic matter (NOM) from several aquatic sites<br />

across Canada and investigated the effects <strong>of</strong> NOM on Pb toxicity in rainbow trout<br />

(Oncorhynchus mykiss). They also looked at toxicity effects as they related to the optical<br />

properties <strong>of</strong> the various NOM samples. The results showed that NOM in test water almost<br />

always increased LT50 and that optically dark NOM tended to decrease Pb toxicity more than did<br />

optically light NOM in rainbow trout.<br />

In summary, non-living constituents <strong>of</strong> biological origin in the environment have been<br />

shown to reduce Pb availability and, there<strong>for</strong>e, toxicity in some aquatic organisms. It is<br />

generally thought that this occurs through complexation or chelation processes that take place in<br />

the water column.<br />

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Physicochemical Environmental Factors<br />

This section reviews the literature on physicochemical environmental factors and their<br />

influence on the bioavailability, uptake, and toxicity <strong>of</strong> Pb in aquatic organisms. These factors<br />

are discussed with regard to their influence individually and in combination.<br />

Studies generally agree that as pH increases, the toxicity <strong>of</strong> Pb decreases (Horne and<br />

Dunson, 1995b; MacDonald et al., 2002). As pH decreases, Pb becomes more soluble and more<br />

readily bioavailable to aquatic organisms (Weber, 1993). Significantly lower survival, decreased<br />

hatching success, slower development, and increased egg mass and larval mortality were<br />

observed in Jefferson salamanders (Ambystoma jeffersonianum) and wood frogs (Rana sylvatica)<br />

exposed to Pb at a pH <strong>of</strong> 4.5 versus a pH <strong>of</strong> 5.5 (Horne and Dunson, 1995b). Contradictory<br />

results have been reported <strong>for</strong> invertebrates. Over a 96-h exposure period, mortality increased<br />

with decreasing pH <strong>for</strong> the bivalve Pisidium casertanum, while pH-independent mortality was<br />

reported <strong>for</strong> gastropods and crustacea under similar exposure conditions (Mackie, 1989).<br />

Cladocerans (C. dubia) and amphipods (H. azteca) were also more sensitive to Pb toxicity at pH<br />

6 to 6.5 than at higher pH levels (Schubauer-Berigan et al., 1993). <strong>Lead</strong> was 100 times more<br />

toxic to the amphipod Hyalella azteca at a pH range <strong>of</strong> 5.0 to 6.0 (Mackie, 1989) than at a pH<br />

range <strong>of</strong> 7.0 to 8.5 (Schubauer-Berigan et al., 1993). <strong>Lead</strong> was also more toxic to fathead<br />

minnows at lower pH levels (Schubauer-Berigan et al., 1993).<br />

The influence <strong>of</strong> pH on Pb accumulation has also been observed in sediments.<br />

Accumulation <strong>of</strong> Pb by the isopod Asellus communis was enhanced at low pH, after a 20-day<br />

exposure to Pb-contaminated sediments (Lewis and McIntosh, 1986). In A. aquaticus,<br />

temperature increases were found to be more important than increased pH in influencing Pb<br />

accumulation (Van Hattum et al., 1996). Increased water temperature was also found to reduce<br />

Pb uptake fluxes in green microalga (Chlorella kesslerii) (Hassler et al., 2004). <strong>Lead</strong> and zinc<br />

body concentrations in Asellus sp. were found to vary markedly with seasonal temperature<br />

changes, with greater concentrations present in spring and summer (Van Hattum et al., 1996).<br />

Acute and chronic toxicity <strong>of</strong> Pb increases with decreasing water hardness, as Pb becomes<br />

more soluble and bioavailable to aquatic organisms (Horne and Dunson, 1995a; Borgmann et al.,<br />

2005). There is some evidence that water hardness and pH work together to increase or decrease<br />

the toxicity <strong>of</strong> Pb. Jefferson salamanders exposed to Pb <strong>for</strong> 28 days at low pH and low water<br />

hardness experienced 50% mortality, while exposure to Pb at high pH and high water hardness<br />

AX7-167


esulted in 91.7% survival (Horne and Dunson, 1995a). Exposure to Pb at high pH and low<br />

water hardness or low pH and high water hardness resulted in 75 and 41.7% survival,<br />

respectively (Horne and Dunson, 1995a). Similar results were reported <strong>for</strong> Jefferson<br />

salamanders during a 7-day exposure and wood frogs during 7- and 28-day exposures (Horne<br />

and Dunson, 1995c). In some cases, water hardness and pH in the absence <strong>of</strong> Pb have been<br />

shown to affect survival adversely. Mean acute survival <strong>of</strong> wood frogs and Jefferson<br />

salamanders exposed to low pH and low water hardness, in the absence <strong>of</strong> Pb, was 83.3 and<br />

91.7%, respectively. Mean chronic survival <strong>of</strong> wood frogs and Jefferson salamanders exposed to<br />

low pH and low water hardness, in the absence <strong>of</strong> Pb, was 79.2 and 41.7%, respectively (Horne<br />

and Dunson, 1995c).<br />

High Ca 2+ concentrations have been shown to protect against the toxic effects <strong>of</strong> Pb<br />

(Sayer et al., 1989; MacDonald et al., 2002; Hassler et al., 2004; Rogers and Wood, 2004).<br />

Calcium affects the permeability and integrity <strong>of</strong> cell membranes and intracellular contents<br />

(Sayer et al., 1989). As Ca 2+ concentrations decrease, the passive flux <strong>of</strong> ions (e.g., Pb) and<br />

water increases. At the lowest waterborne Ca 2+ concentration (150 µmol/L), Pb accumulation in<br />

juvenile rainbow trout (Oncorhynchus mykiss) branchials significantly increased as Pb<br />

concentration in water increased (Rogers and Wood, 2004). At higher Ca 2+ concentrations, Pb<br />

accumulation did not significantly increase with Pb concentration in water. This result<br />

demonstrates the protective effects <strong>of</strong> waterborne Ca 2+ and supports the suggestion that the Ca 2+<br />

component <strong>of</strong> water hardness determines the toxicity <strong>of</strong> Pb to fish (Rogers and Wood, 2004).<br />

Rogers and Wood (2004) reported that the uptake <strong>of</strong> Ca 2+ and Pb 2+ involves competitive<br />

inhibition <strong>of</strong> apical entry at lanthanum-sensitive Ca 2+ channels and interference with the function<br />

<strong>of</strong> the ATP-driven baso-lateral Ca 2+ pump. High mortality was reported in brown trout (Salmo<br />

trutta) fry exposed to Pb at a waterborne Ca 2+ concentration <strong>of</strong> 20 µmol/L, while negligible<br />

mortality was reported at the same Pb concentration but at a waterborne Ca 2+ concentration <strong>of</strong><br />

200 µmol/L (Sayer et al., 1989). Adverse effects to mineral uptake and skeletal development<br />

were observed in the latter test group (Sayer et al., 1989).<br />

The bioavailability <strong>of</strong> Pb and other metals that can be simultaneously extracted in<br />

sediments may be modified through the role <strong>of</strong> acid volatile sulfide (AVS) under anoxic<br />

conditions (Tessier and Campbell, 1987; Di Toro et al., 1992; Casas and Crecelius, 1994). The<br />

term AVS (iron sulfide is an example) refers to the fraction <strong>of</strong> the sediment that consists <strong>of</strong> a<br />

AX7-168


eactive pool <strong>of</strong> solid-phase sulfide. This phase is available to bind divalent metals that then<br />

become unavailable <strong>for</strong> uptake by aquatic biota. The models proposed by Di Toro et al. (1992)<br />

and Casas and Crecelius (1994) predict that when the molar ratio <strong>of</strong> simultaneously extractable<br />

metals (SEM) to AVS in sediments is less than one, the metals will not be bioavailable due to<br />

complexation with available sulfide.<br />

Salinity is an important modifying factor to metal toxicity. Verslycke et al. (2003)<br />

exposed the estuarine mysid Neomysis integer to individual metals, including Pb, and metal<br />

mixtures under changing salinity. At a salinity <strong>of</strong> 5%, the reported LC50 <strong>for</strong> Pb was 1140 µg/L<br />

(95% CL = 840, 1440 µg/L). At an increased salinity <strong>of</strong> 25l, the toxicity <strong>of</strong> Pb was substantially<br />

reduced (LC50 = 4274 µg/L [95% CL = 3540, 5710 µg/L]) (Verslycke et al., 2003). The<br />

reduction in toxicity was attributed to increased complexation <strong>of</strong> Pb 2+ with Cl ! ions.<br />

Nutritional Factors<br />

The relationship between nutrition and Pb toxicity has not been thoroughly investigated in<br />

aquatic organisms. In fact, algae species are the only aquatic organisms to have been studied<br />

fairly frequently. Although nutrients have been found to have an impact on Pb toxicity, the<br />

mechanisms involved are poorly understood. It is unclear whether the relationship between<br />

nutrients and toxicity comprises organismal nutrition (the process by which a living organism<br />

assimilates food and uses it <strong>for</strong> growth and <strong>for</strong> replacement <strong>of</strong> tissues), or whether nutrients have<br />

interacted directly with Pb, inhibiting its metabolic interaction in the organism. This section<br />

reviews the little in<strong>for</strong>mation that has been gathered from studies documenting apparent Pbnutrition<br />

associations in aquatic organisms.<br />

Jampani (1988) looked at the impact <strong>of</strong> various nutrients (i.e., sodium acetate, citric acid,<br />

sodium carbonate, nitrogen, and phosphates) on reducing growth inhibition in blue-green algae<br />

(Synechococcus aeruginosus) exposed to 200 mg Pb/L. Exposure to this Pb treatment<br />

concentration caused 100% mortality in algae. Results indicated that additional nitrogen,<br />

phosphates, and some carbon sources, including sodium acetate, citric acid and sodium<br />

carbonate, all protected the algae from Pb toxicity. Algae that had been starved prior to the<br />

experiment were found to be significantly more sensitive to Pb exposure. Glucose was the only<br />

nutrient tested that did not have a significant impact on Pb toxicity in S. aeruginosus. In a<br />

similar study by Rao and Reddy (1985) on Scenedesmus incrassatulus, nitrogen, phosphate and<br />

AX7-169


carbon sources (including glucose), all had protective effects, and reduced Pb toxicity at 300 and<br />

400 mg Pb/L. Both studies proposed similar hypotheses regarding nutrient-Pb mechanisms that<br />

led to reduced toxicity. One hypothesis was that the nutrients were able to reverse toxic effects.<br />

The second hypothesis was that the nutrients interacted directly with Pb, in some way<br />

sequestering the metal so as to inhibit its metabolic interaction with the organism (Rao and<br />

Reddy, 1985; Jampani, 1988).<br />

Rai and Raizada (1989) investigated the effects <strong>of</strong> Pb on nitrate and ammonium uptake as<br />

well as carbon dioxide and nitrogen fixation in Nostoc muscorum over a 96-h period. Test<br />

specimens were exposed to 10, 20, and 30 mg Pb/L. At 20 mg Pb/L, nitrate uptake was inhibited<br />

by 64% after 24 h and by 39% after 96 h. Ammonium uptake was inhibited, and similarly,<br />

inhibition decreased from 72% inhibition after 24 h to 26% inhibition after 96 h <strong>of</strong> exposure.<br />

Carbon dioxide fixation and nitrogenase activity followed similar patterns, and results indicated<br />

that Pb exposure can affect the uptake <strong>of</strong> some nutrients in N. muscorum.<br />

Adam and Abdel-Basset (1990) studied the effect <strong>of</strong> Pb on metabolic processes <strong>of</strong><br />

Scenedesmus obliquus. They found that nitrogenase activity was inhibited by Pb nitrate, but<br />

enhanced by Pb-acetate. As photosynthetic products and respiratory substrates, carbohydrate<br />

and lipid levels were altered by Pb. Above 30 mg/L <strong>of</strong> Pb-nitrate, both macronutrients were<br />

reduced. However, Pb-acetate was found to increase carbohydrate levels. Results suggest that<br />

Pb can have an effect on macronutrients in S. obliquus and that effects may vary depending on<br />

the chemical species.<br />

Simòes Gonçalves et al. (1991) studied the impact <strong>of</strong> light, nutrients, air flux, and Pb, in<br />

various combinations, on growth inhibition in the green algae Selenastrum capricornutum.<br />

Results indicated that at lower Pb concentrations (


Amiard et al. (1994) investigated the impact on s<strong>of</strong>t tissue Pb concentrations <strong>of</strong> various<br />

feeding regimes on oysters (Crassostrea gigas) during their spat rearing. They fed test groups <strong>of</strong><br />

C. gigas different amounts <strong>of</strong> Skeletonema costatum and additional natural phytoplankton grown<br />

in test solutions. Results showed that size and food intake both negatively correlated with metal<br />

concentrations in s<strong>of</strong>t tissue. The authors hypothesized that this relationship was due in part to a<br />

diluting effect <strong>of</strong> the food.<br />

In summary, nutrients affect Pb toxicity in those aquatic organisms that have been studied.<br />

Some nutrients seem to be capable <strong>of</strong> reducing toxicity, though the mechanisms have not been<br />

well established. Exposure to Pb has not been shown to reduce nutrient uptake ability, though it<br />

has been demonstrated that Pb exposure may lead to increased production and loss <strong>of</strong> organic<br />

material (e.g., mucus and other complex organic ligands) (Capelo et al., 1993).<br />

Interactions with Other Pollutants<br />

Most <strong>of</strong> the scientific literature reviewed in this section considered how Pb and other<br />

elements combine to affect uptake and exert toxicity. Research on the interactions <strong>of</strong> Pb with<br />

complexing ligands and other physical and biological factors was more thoroughly discussed in<br />

Section AX7.2.3.4. Predicting the response <strong>of</strong> organisms to mixtures <strong>of</strong> chemicals is difficult<br />

(Norwood et al., 2003). There are two schools <strong>of</strong> thought on addressing chemical mixtures in<br />

toxicology. The first focuses on the combined mode <strong>of</strong> action <strong>of</strong> the individual mixture<br />

substances while the other focuses on the organism response to the mixture as being additive, or<br />

some deviation from additive (synergistic or antagonistic). The mode <strong>of</strong> action model assumes<br />

that each <strong>of</strong> the individual substances has similar pharmacokinetics as well as mode <strong>of</strong> action.<br />

Approaches to modeling combined mode <strong>of</strong> action include: 1) joint independent action <strong>for</strong><br />

toxicants with different modes <strong>of</strong> action; and 2) joint similar mode <strong>of</strong> action. Within the<br />

scientific literature the deviations from additivity approach can be confusing as some authors<br />

report concentration additivity, while others report effect additivity. The concentration additivity<br />

model assumes that the sum <strong>of</strong> the concentrations will result in a level <strong>of</strong> effect similar to the<br />

simple sum <strong>of</strong> the effects observed if each chemical were applied separately (e.g., Herkovits and<br />

Perez-Coll, 1991). Toxic units (TU) may be used to describe the concentration additivity results<br />

<strong>for</strong> mixtures (e.g., Hagopian-Schlekat et al., 2001). Effects additivity suggests that the level <strong>of</strong><br />

effect <strong>of</strong> a mixture will be the sum <strong>of</strong> the effects <strong>of</strong> each chemical used separately. Thus, the<br />

AX7-171


separate concentration-effects models <strong>for</strong> each chemical are used to predict individual effects and<br />

the sum <strong>of</strong> these predictions is then compared to the actual effect <strong>of</strong> the mixture. Deviations<br />

from the mixture effect are then classified as less than additive (antagonistic) or more than<br />

additive (synergistic) (see Piegorsch et al., 1988; Finney 1947 <strong>for</strong> further in<strong>for</strong>mation).<br />

The complexity <strong>of</strong> metal mixture interactions as different metal concentrations,<br />

environmental conditions (e.g., temperature, pH), and other factors can cause marked changes in<br />

the effects observed (Norwood et al., 2003). In describing Pb interactions with other elements,<br />

the different approaches to modeling mixture toxicity are considered. Specific reference to<br />

known Pb-metal interactions and implications on Pb uptake and toxicity will also be made in<br />

each <strong>of</strong> the studies below.<br />

Less than additive or antagonistic interactions can reduce metal bioavailability when<br />

metals are present in combination, and may lead to reduced potential <strong>for</strong> toxicity (Hassler et al.,<br />

2004). A number <strong>of</strong> elements act in an antagonistic fashion with Pb. For example, Pb is a wellknown<br />

antagonist to Ca 2+ (Niyogi and Wood, 2004; Hassler et al., 2004), which is an essential<br />

element, required <strong>for</strong> a number <strong>of</strong> physiological processes in most organisms. <strong>Lead</strong> ions have an<br />

atomic structure similar to Ca 2+ and can be transported either actively or passively across cell<br />

membranes in place <strong>of</strong> Ca 2+ . An example <strong>of</strong> this interaction was reported by Behra (1993a,b)<br />

where Pb was shown to activate calmodulin reactions in rainbow trout (O. mykiss) and sea<br />

mussel (Mytilus sp.) tissues in the absence <strong>of</strong> calcium. Calmodulin (CaM) is a major<br />

intracellular calcium receptor and regulates the activities <strong>of</strong> numerous enzymes and cellular<br />

processes. Allen (1994) reported that Pb can replace calcium in body structures (e.g., bones,<br />

shells); replace zinc in ALAD, which is required <strong>for</strong> heme biosynthesis; and react with<br />

sulfhydryl groups, causing con<strong>for</strong>mation protein distortion and scission <strong>of</strong> nucleic acids<br />

(Herkovits and Perez-Coll, 1991). <strong>Lead</strong> is also a known antagonist to Mg 2+ , Na + , and Cl !<br />

regulation in fish (Ahern and Morris, 1998; Rogers and Wood, 2003, 2004; Niyogi and Wood,<br />

2004). Li et al. (2004) reported on the interaction <strong>of</strong> Pb 2+ with Cd 2+ in the context <strong>of</strong> adsorption<br />

from solution by Phanerochaete chrysosporium, a filamentous fungus. The authors found that<br />

cadmium uptake decreased with increasing concentration <strong>of</strong> Pb ions with Pb 2+ outcompeting<br />

Cd 2+ <strong>for</strong> binding sites.<br />

Hassler et al. (2004) reported that in the presence <strong>of</strong> copper (Cu 2+ ), there was a<br />

significantly higher rate <strong>of</strong> internalization <strong>of</strong> Pb in the green algae Chlorella kesserii. It was<br />

AX7-172


suggested that Cu 2+ may have affected organism physiology through the disruption <strong>of</strong> cell<br />

membrane integrity. This would allow increased cation (i.e., Pb 2+ ) permeability and, there<strong>for</strong>e,<br />

substantially increase internalization <strong>of</strong> Pb and result in effects that were more than additive<br />

(synergistic). Hagopian-Schlekat et al. (2001) examined the impact <strong>of</strong> individual metals and<br />

complex metal mixtures containing Cd, Cu, Ni, Zn, and Pb to the estuarine copepod Amphiascus<br />

tenuiremis. The copepods were exposed to metal-spiked sediment and pore water. The mixed<br />

metal sediment toxicity tests demonstrated greater than additive toxicity to A. tenuiremis. It was<br />

postulated that the synergism observed was due to two or more metals affecting the same<br />

biological function. Herkovits and Perez-Coll (1991) exposed Bufo arenarum larvae to various<br />

Pb and zinc concentrations in solution. At low zinc concentrations, (2:1 Pb:Zn ratio),<br />

a synergistic toxic effect was observed in the frog larvae relative to the effects observed from<br />

exposure to the individual metals and at higher zinc concentrations. Enhanced Pb toxicity was<br />

attributed to the interference <strong>of</strong> Pb with cellular activities due to binding with sulfhydryl<br />

polypeptides and nucleic acid phosphates (Herkovits and Perez-Coll, 1991). Allen (1994)<br />

reported on the accumulation <strong>of</strong> numerous metals and ions into specific tissues <strong>of</strong> the tilapia<br />

Oreochromis aureus. Tilapia exposed to low concentrations <strong>of</strong> Pb and mercury (both at<br />

0.05 mg/L) had significantly higher concentrations <strong>of</strong> Pb in internal organs than those fish<br />

exposed to Pb alone. Similarly, low concentrations <strong>of</strong> cadmium with low concentrations <strong>of</strong> Pb<br />

caused increased uptake <strong>of</strong> Pb in certain organs (e.g., liver, brain, and caudal muscle).<br />

<strong>Lead</strong> has been shown to complex with Cl ! in aquatic systems. For example, Verslycke<br />

et al. (2003) exposed the estuarine mysid Neomysis integer to six different metals, including Pb,<br />

and a combined metal mixture under changing salinity conditions. At a salinity <strong>of</strong> 5%, the<br />

reported LC50 <strong>for</strong> Pb was 1140 µg/L (840, 1440 µg/L). At an increased salinity <strong>of</strong> 25l, the<br />

toxicity <strong>of</strong> Pb was substantially reduced (LC50 = 4274 µg/L [3540, 5710 Φg/L]) (Verslycke<br />

et al., 2003). This reduction in toxicity was attributed to the increased concentration <strong>of</strong> Cl ! ion<br />

due to increased salinity, in that it complexed with divalent Pb in the test system. Exposure <strong>of</strong> N.<br />

integer to Pb in combination with the other five metals (Hg, Cd, Cu, Zn, Ni) resulted in roughly<br />

strictly additive toxicity (Verslycke et al., 2003).<br />

Long et al. (2006) per<strong>for</strong>med a critical review <strong>of</strong> the uses <strong>of</strong> mean sediment quality<br />

guideline quotients (mSQGQs) in assessing the toxic effects <strong>of</strong> contaminant mixtures (metals and<br />

organics) in sediments. This approach has been used in numerous surveys and studies since<br />

AX7-173


1994. mSQGQs are useful to risk assessors but their inherent limitations and underlying<br />

assumptions must be fully understood (see Section AX7.2.1.5).<br />

Summary <strong>of</strong> Interactions With Other Pollutants<br />

Norwood et al. (2003) reported that in a review and reinterpretation <strong>of</strong> published data on<br />

the interactions <strong>of</strong> metals in binary mixtures (n = 15 studies), antagonistic (6) and additive<br />

interactions (6) were the most common <strong>for</strong> Pb. The complexity <strong>of</strong> the interactions and possible<br />

modifying factors makes determining the impact <strong>of</strong> even binary metal mixtures to aquatic biota<br />

difficult (Norwood et al., 2003; Playle, 2004). The two most commonly reported Pb-element<br />

interactions are between Pb and calcium and between Pb and zinc. Both calcium and zinc are<br />

essential elements in organisms and the interaction <strong>of</strong> Pb with these ions can lead to adverse<br />

effects both by increased Pb uptake and by a decrease in Ca and Zn required <strong>for</strong> normal<br />

metabolic functions.<br />

AX7.2.3.5 Factors Associated with Global Climate Change<br />

It is highly unlikely that Pb has any influence on generation <strong>of</strong> ground-level ozone,<br />

depletion <strong>of</strong> stratospheric ozone, global warming, or other indicators <strong>of</strong> global climate change.<br />

<strong>Lead</strong> compounds have relatively short residence times in the atmosphere, making it unlikely that<br />

they will reach the stratosphere, and they do not absorb infrared radiation, making them unlikely<br />

to contribute to stratospheric ozone depletion or global warming. Also, these compounds are<br />

unlikely to have a significant interaction with ground-level nitrogen oxides or volatile organic<br />

compounds, thus precluding generation <strong>of</strong> ground-level ozone.<br />

Approached from another viewpoint, climate change can have a major impact on the<br />

fate/behavior <strong>of</strong> Pb in the environment and, there<strong>for</strong>e, can subsequently alter organism or<br />

ecosystem responses. For example, changes in temperature regime (Q10 rule), changes in<br />

precipitation quantity and quality (e.g., acidic deposition) may influence fate, transport, uptake,<br />

and bioavailability <strong>of</strong> Pb (Syracuse Research Corporation., 1999).<br />

AX7.2.3.6 Summary<br />

There have been a number <strong>of</strong> advancements in the understanding <strong>of</strong> Pb behavior in the<br />

environment and its impact on aquatic organisms since 1986. In particular, greater knowledge <strong>of</strong><br />

AX7-174


factors that influence Pb accumulation in aquatic organisms, mechanisms <strong>of</strong> detoxification and<br />

avoidance <strong>of</strong> Pb, and greater understanding <strong>of</strong> the interactions <strong>of</strong> Pb in aquatic systems. All <strong>of</strong><br />

these factors require some consideration when attempting to determine the potential <strong>for</strong> exposure<br />

and subsequent response <strong>of</strong> aquatic species to lead. The following section provides a review on<br />

the current understanding <strong>of</strong> lead and its impacts on aquatic biota.<br />

AX7.2.4 Exposure/Response <strong>of</strong> Aquatic Species<br />

This section outlines and highlights the critical recent advancements in the understanding<br />

<strong>of</strong> the toxicity <strong>of</strong> Pb to aquatic biota. The section begins with a review <strong>of</strong> the major findings and<br />

conclusions from the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a). The<br />

following sections summarize the research conducted since 1986 on determining the<br />

concentrations <strong>of</strong> Pb that cause the effects discussed in Section 7.2.3.<br />

<strong>Lead</strong> exposure may adversely affect organisms at different levels <strong>of</strong> organization, i.e.,<br />

individual organisms, populations, communities, or ecosystems. Generally, however, there is<br />

insufficient in<strong>for</strong>mation available <strong>for</strong> single materials in controlled studies to permit evaluation<br />

<strong>of</strong> specific impacts on higher levels <strong>of</strong> organization (beyond the individual organism). Potential<br />

effects at the population level or higher are, <strong>of</strong> necessity, extrapolated from individual level<br />

studies. Available population, community, or ecosystem level studies are typically conducted at<br />

sites that have been contaminated or adversely affected by multiple stressors (several chemicals<br />

alone or combined with physical or biological stressors). There<strong>for</strong>e, the best documented links<br />

between lead and effects on the environment are with effects on individual organisms. Impacts<br />

on aquatic ecosystems are discussed in Section 7.2.5 and Annex AX7.2.5.<br />

AX7.2.4.1 Summary <strong>of</strong> Conclusions From the Previous <strong>Criteria</strong> Document<br />

The 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a) reviewed data in<br />

the context <strong>of</strong> the sublethal effects <strong>of</strong> lead exposure. The document focused on describing the<br />

types and ranges <strong>of</strong> lead exposures in ecosystems likely to adversely impact domestic animals.<br />

As such, the criteria document did not provide a comprehensive analysis <strong>of</strong> the effects <strong>of</strong> lead to<br />

most aquatic primary producers, consumers, and decomposers. For the aquatic environment,<br />

general reviews <strong>of</strong> the effects <strong>of</strong> lead to algae, aquatic vertebrates, and invertebrates were<br />

undertaken. A summary <strong>of</strong> these reviews is provided below.<br />

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Algae<br />

The 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a) reported that<br />

some algal species (e.g., Scenedesmus sp.) were found to exhibit physiological changes when<br />

exposed to high lead or organolead concentrations in situ. The observed changes included<br />

increased numbers <strong>of</strong> vacuoles, de<strong>for</strong>mations in cell organelles, and increased autolytic activity.<br />

Increased vacuolization was assumed to be a tolerance mechanism by which lead was<br />

immobilized within cell vacuoles.<br />

Aquatic Vertebrates<br />

The 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a) reported that<br />

hematological and neurological responses were the most commonly reported effects in aquatic<br />

vertebrates. These effects include red blood cell destruction and inhibition <strong>of</strong> the enzyme<br />

ALAD, required <strong>for</strong> hemoglobin synthesis. At high lead concentrations, neurological responses<br />

included neuromuscular distortion, anorexia, muscle tremor, and spinal curvature (e.g., lordosis).<br />

The lowest reported exposure concentration causing either hematological or neurological effects<br />

was 8 µg/L (U.S. Environmental Protection Agency, 1986a).<br />

Aquatic Invertebrates<br />

Numerous studies were cited on the effects <strong>of</strong> lead to aquatic invertebrates in the 1986<br />

<strong>Lead</strong> AQCD (U.S. Environmental Protection Agency, 1986a). In general, lead concentrations in<br />

aquatic invertebrates were found to be correlated closely with concentrations in water rather than<br />

food. Freshwater snails were found to accumulate lead in s<strong>of</strong>t tissue, <strong>of</strong>ten in granular bodies <strong>of</strong><br />

precipitated lead. Mortality and reproductive effects were reported to begin at 19 µg Pb/L <strong>for</strong> the<br />

freshwater snail Lymnea palutris and 27 µg Pb/L <strong>for</strong> Daphnia sp.<br />

The review <strong>of</strong> the NAAQS <strong>for</strong> Pb (U.S. Environmental Protection Agency, 1990) made<br />

only one recommendation reported in the sections <strong>of</strong> the 1986 <strong>Lead</strong> AQCD dealing with effects<br />

to aquatic biota. This was the need to consider the impact <strong>of</strong> water hardness on Pb<br />

bioavailability and toxicity, to be consistent with the recommendations <strong>of</strong> the AWQC <strong>for</strong> the<br />

protection <strong>of</strong> aquatic life (U.S. Environmental Protection Agency, 1985).<br />

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AX7.2.4.2 Recent Studies on Effects <strong>of</strong> <strong>Lead</strong> on Primary Producers<br />

Using literature published since the 1986 <strong>Lead</strong> AQCD (U.S. Environmental Protection<br />

Agency, 1986a), this section examines the toxicity <strong>of</strong> Pb (individually and in metal mixtures) to<br />

algal and aquatic plant growth, its effects on metabolic processes (e.g., nutrient uptake), and its<br />

impact on primary productivity in natural systems.<br />

Toxicity <strong>of</strong> <strong>Lead</strong> to Algae<br />

The toxicity <strong>of</strong> Pb to algal growth has been investigated <strong>for</strong> a number <strong>of</strong> species including<br />

Chlorella vulgaris, Closterium acerosum, Pediastrum simplex, Scenedesmus quadricauda,<br />

Scenedesmu obliquus, Syneschoccus aeruginosus, and Nostoc muscorum (Jampani, 1988; Rai<br />

and Raizada, 1989; Adam and Abdel-Basset, 1990; Fargašová, 1993; Bilgrami and Kumar,<br />

1997). Study durations ranged from 7 to 20 days and Pb-nitrate was the most commonly used<br />

<strong>for</strong>m <strong>of</strong> Pb. Effects to algal growth (Chlorella vulgaris, Closterium acerosum, Pediastrum<br />

simplex, Scenedesmus quadricauda), ranging from minimal to complete inhibition, have been<br />

reported at Pb concentrations between 100 and 200,000 µg/L (Jampani, 1988; Bilgrami and<br />

Kumar, 1997). Most studies report the percent inhibition in test groups compared to controls<br />

rather than calculating the LOEC, NOEC, or EC50 values. Clinical signs <strong>of</strong> Pb toxicity include<br />

the de<strong>for</strong>mation and disintegration <strong>of</strong> algae cells and a shortened exponential growth phase<br />

(Jampani, 1988; Fargašová, 1993). Other effects <strong>of</strong> Pb block the pathways that lead to pigment<br />

synthesis, thus affecting photosynthesis, the cell cycle and division, and ultimately result in cell<br />

death (Jampani, 1988).<br />

From the studies reviewed, Closterium acerosum is the most sensitive alga species tested<br />

(Bilgrami and Kumar, 1997). Exposure <strong>of</strong> these algae to 1000 and 10,000 µg/L as lead nitrate<br />

<strong>for</strong> 6 days resulted in cell growth that was 52.6 and 17.4%, respectively, <strong>of</strong> controls (Bilgrami<br />

and Kumar, 1997). Chlorella vulgaris, Pediastrum simplex, and Scenedesmus quadricauda were<br />

also exposed to Pb-nitrate in this study. Compared to controls, cell growth at 1000 and<br />

10,000 µg Pb-nitrate/L was 65.3 and 48.7%, 64.5 and 42.7%, and 77.6 and 63.2%, respectively<br />

(Bilgrami and Kumar, 1997). Scenedesmus quadricauda exhibited a similar magnitude <strong>of</strong> effects<br />

when exposed to lead (Pb 2+ ) <strong>for</strong> 20 days at 0, 5500, 11,000, 16,500, 22,000, 27,500, and<br />

33,000 µg/L (Fargašová, 1993). This study reported an EC50 <strong>for</strong> growth inhibition at<br />

13,180 µg/L (95% CI: 10,190, 14,620). Decreased cell number, but increased cell size, was<br />

AX7-177


observed in Selenastrum capricornutum 7 exposed to lead (Pb 2+ ) at 207.2 µg/L and a Q/V (flux <strong>of</strong><br />

air [Q] divided by volume <strong>of</strong> the culture [V]) <strong>of</strong> 4.7 Η 10 !3 sec !1 <strong>for</strong> 9 days (Simòes Gonçalves<br />

et al., 1991). The Q/V is a measure <strong>of</strong> culture growth where an increase in the Q/V ratio<br />

indicates growth. The pigment concentration per cell decreased with exposure to Pb, so while<br />

the algae cells were larger, they were less healthy (Simòes Gonçalves et al., 1991). Growth rates<br />

were not reported, making comparison with other studies difficult.<br />

High Pb concentrations were required to elicit effects in Nostoc muscorum and<br />

Scenedesmus aeruginosus (Jampani, 1988; Rai and Raizada, 1989). Following 15-day<br />

exposures, test groups exposed to 10,000, 20,000, and 30,000 µg Pb/L experienced growth rates<br />

that were 90.5, 76.9, and 66.7% <strong>of</strong> the controls (Rai and Raizada, 1989). Synechococcus<br />

aeruginosus experienced little inhibition <strong>of</strong> growth from exposure to Pb-nitrate up to a<br />

concentration <strong>of</strong> 82,000 µg/L (Jampani, 1988). At a test concentration <strong>of</strong> 100,000 µg/L,<br />

complete inhibition <strong>of</strong> growth was observed, and at a concentration <strong>of</strong> 200,000 µg/L, algae failed<br />

to establish a single colony (Jampani, 1988). Scenedesmus obliquus are quite tolerant to the<br />

effects <strong>of</strong> Pb-nitrate and Pb-acetate on growth. Algae exposed to Pb-nitrate or Pb-acetate up to<br />

180,000 µg/L had higher cell numbers than controls (Adam and Abdel-Basset, 1990). Exposure<br />

to the highest concentration <strong>of</strong> 300,000 µg/L Pb-nitrate or Pb-acetate resulted in cell numbers<br />

that were 81 and 90% <strong>of</strong> the controls, respectively (Adam and Abdel-Basset, 1990).<br />

<strong>Lead</strong> in combination with other metals (e.g., Pb and Cd, Pb and Ni, etc.) is generally less<br />

toxic than exposure to Pb alone (Rai and Raizada, 1989). Nostoc muscorum exposed to<br />

chromium and Pb in combination demonstrated better growth than when exposed to either <strong>of</strong> the<br />

metals alone (Rai and Raizada, 1989). Antagonistic interaction was observed in the exposure <strong>of</strong><br />

Nostoc muscorum to Pb and nickel in combination (Rai and Raizada, 1989). When applied<br />

separately, these metals demonstrated different levels <strong>of</strong> toxicity; however, in combination, they<br />

exerted similar effects (Rai and Raizada, 1989). More in<strong>for</strong>mation on toxic interactions <strong>of</strong> Pb<br />

with other metals is provided in Section AX7.2.3.5.<br />

7<br />

The species name Selenastrum capricornutum has been changed to Pseudokirchneriella subcapitata. The<br />

<strong>for</strong>mer species name is used in this report.<br />

AX7-178


Aquatic Plants<br />

The toxicity <strong>of</strong> Pb to aquatic plant growth has been studied using Spirodela polyrhiza,<br />

Azolla pinnata, and Lemna gibba (Gaur et al., 1994; Gupta and Chandra, 1994; Miranda and<br />

Ilangovan, 1996). Test durations ranged from 4 to 25 days and test concentrations ranged<br />

between 49.7 and 500,000 µg Pb/L (Gaur et al., 1994; Miranda and Ilangovan, 1996). Research<br />

on aquatic plants has focused on the effects <strong>of</strong> Pb on aquatic plant growth and chlorophyll and<br />

protein content.<br />

Of the species reviewed here, the effects <strong>of</strong> Pb on aquatic plant growth are most<br />

pronounced in Azolla pinnata (Gaur et al., 1994). An EC50 <strong>of</strong> 1100 µg/L was reported <strong>for</strong><br />

A. pinnata exposed to Pb-nitrate <strong>for</strong> 4 days. S. polyrhiza exposed to Pb-nitrate under the same<br />

test conditions had a reported EC50 <strong>for</strong> growth <strong>of</strong> 3730 µg/L (Gaur et al., 1994). Lemna gibba<br />

was shown to be the least sensitive plant species to Pb: significant growth inhibition was<br />

reported at concentrations <strong>of</strong> 200,000 µg/L or greater after 25 days <strong>of</strong> exposure to concentrations<br />

<strong>of</strong> 30,000, 50,000, 100,000, 200,000, 300,000, or 500,000 µg/L (Miranda and Ilangovan, 1996).<br />

The maximum growth rate <strong>for</strong> L. gibba was observed at 10 days <strong>of</strong> exposure. After this point,<br />

the growth rate declined in controls and test concentrations (Miranda and Ilangovan, 1996).<br />

Clinical signs <strong>of</strong> Pb toxicity include yellowing and disintegration <strong>of</strong> fronds, reduced frond size,<br />

and chlorosis (Gaur et al., 1994; Miranda and Ilangovan, 1996). Toxicity results suggest that<br />

effects to growth from Pb exposure occur in a dose-dependent manner (Gaur et al., 1994).<br />

Effects <strong>of</strong> <strong>Lead</strong> on Metabolic Processes<br />

Algal and aquatic plant metabolic processes are variously affected by exposure to Pb, both<br />

singularly and in combination with other metals. <strong>Lead</strong> adversely affects the metabolic processes<br />

<strong>of</strong> nitrate uptake, nitrogen fixation, ammonium uptake, and carbon fixation at concentrations <strong>of</strong><br />

20,000 µg Pb/L or greater (Rai and Raizada, 1989). <strong>Lead</strong> in combination with nickel has an<br />

antagonistic effect on nitrogen fixation and ammonium uptake, but a synergistic effect on nitrate<br />

uptake and carbon fixation (Rai and Raizada, 1989). <strong>Lead</strong> in combination with chromium has an<br />

antagonistic effect on nitrate uptake, but it has a synergistic effect on nitrogen fixation,<br />

ammonium uptake, and carbon fixation (Rai and Raizada, 1989).<br />

<strong>Lead</strong> effects on nitrate uptake in Nostoc muscorum (µg NO3/µg Chl a) were greatest after<br />

24 h, when exposure to 20,000 µg/L reduced nitrate uptake by 64.3% compared to controls.<br />

AX7-179


Nitrate uptake reported after 48, 72, and 96 h was reduced by 30.0, 37.5, and 38.9%,<br />

respectively, compared to controls (Rai and Raizada, 1989). <strong>Lead</strong> in combination with<br />

chromium, both at a test concentration <strong>of</strong> 20,000 µg/L, demonstrated antagonistic effects on<br />

nitrate uptake. Compared to controls, nitrate uptake was reduced by 52.4, 30, 25, and 22.2% at<br />

24, 48, 72 and 96 h, respectively (Rai and Raizada, 1989). The greatest effect on uptake<br />

occurred at 24 h when, compared to controls, a 52.4% reduction was reported in the test<br />

concentration. <strong>Lead</strong> and nickel in combination at test concentrations <strong>of</strong> 20,000 and 1000 µg/L,<br />

respectively, resulted in a greater reduction <strong>of</strong> nitrate uptake than Pb alone at 48, 72, and 96 h<br />

(Rai and Raizada, 1989).<br />

After 24, 48, and 72 h <strong>of</strong> Pb exposure at 20,000 µg/L, nitrogenase activity (nmol C2H4/ µg<br />

protein/hr) in Nostoc muscorum was reduced by 39.3, 61.8, and 14.1%, respectively, compared<br />

to controls (Rai and Raizada, 1989). A concentration <strong>of</strong> 207.2 µg Pb/L had little effect on<br />

nitrogen or phosphorus assimilation in Selenastrum capricornutum over 7 days (Capelo et al.,<br />

1993). An antagonistic effect on nitrogenase activity was generally reported <strong>for</strong> Nostoc<br />

muscorum exposed to Pb in combination with nickel at 20,000 and 1,000 µg/L, respectively<br />

(Rai and Raizada, 1989). Compared to controls, nitrogenase activity was reduced by 42.9, 32.7,<br />

and 13.6% at 24, 48, and 72 h, respectively (Rai and Raizada, 1989). <strong>Lead</strong> and chromium, both<br />

administered at a concentration <strong>of</strong> 20,000 µg/L, had a synergistic impact on nitrogenase activity<br />

in Nostoc muscorum. Nitrogenase activity in the test group was reduced by 60.7, 60, and 50%<br />

compared to the controls at 24, 48, and 72 h, respectively (Rai and Raizada, 1989).<br />

<strong>Lead</strong>-induced inhibition <strong>of</strong> ammonium uptake (µg NH4 uptake/µg Chl a) was greatest in<br />

Nostoc muscorum after 48 h <strong>of</strong> exposure to 20,000 µg/L <strong>of</strong> lead. Compared to controls, the Pb<br />

test concentration 20,000 µg/L reduced ammonium uptake by 72, 82, 61, and 26 % at 24, 48, 72,<br />

and 96 h, respectively (Rai and Raizada, 1989). <strong>Lead</strong> in combination with nickel at<br />

concentrations <strong>of</strong> 20,000 and 1,000 µg/L, respectively, demonstrated an antagonistic effect on<br />

ammonium uptake. Compared to controls, ammonium uptake in the test group was reduced by<br />

44.9, 54.1, 23.3, and 4% at 24, 48, 72, and 96 h, respectively (Rai and Raizada, 1989). <strong>Lead</strong> in<br />

combination with chromium, both at concentrations <strong>of</strong> 20,000 µg/L, demonstrated a synergistic<br />

interaction with 24, 48, 72, and 96 h uptake rates reduced by 87.2, 88.5, 72.5, and 50 %,<br />

respectively, compared to controls (Rai and Raizada, 1989).<br />

AX7-180


Nostoc muscorum exposed to 20,000 µg Pb/L experienced the greatest reduction in carbon<br />

fixation at 0.5 h <strong>of</strong> exposure: 62% compared to controls. Inhibition <strong>of</strong> carbon fixation in the test<br />

group was less pronounced after 1 and 2 h <strong>of</strong> exposure: 29 and 13% <strong>of</strong> controls (Rai and<br />

Raizada, 1989). <strong>Lead</strong> in combination with nickel or chromium had synergistic effects to carbon<br />

fixation. <strong>Lead</strong> and nickel concentrations <strong>of</strong> 20,000 and 1000 µg/L, respectively, resulted in 0.5,<br />

1, and 2 h carbon fixation rates reduced by 93, 92, and 91%, respectively, compared to controls<br />

(Rai and Raizada, 1989). <strong>Lead</strong> with chromium at concentrations <strong>of</strong> 20,000 µg/L resulted in 0.5,<br />

1, and 2 h carbon fixation rates reduced by 65, 58, and 50%, respectively, compared to controls.<br />

Nutrients such as nitrogen, phosphate, sodium acetate, sodium carbonate, and citric acid<br />

have been shown to protect against the toxic effects <strong>of</strong> Pb to algae (Jampani, 1988). Nitrogen<br />

compounds (ammonium chloride, potassium nitrate, sodium nitrate, sodium nitrite) protected<br />

Synechococcus aeruginosus from a lethal Pb-nitrate dose <strong>of</strong> 200,000 µg/L (Jampani, 1988). Two<br />

phosphates (K2HPO4 and Na2HPO4) were found to improve Synechococcus aeruginosus survival<br />

from 0 to 72% at 200,000 µg/L <strong>of</strong> Pb-nitrate (Jampani, 1988).<br />

Compared to controls, protein content was reduced by 54.2 and 51.9% in aquatic plants<br />

Vallisneria spiralis and Hydrilla verticillata, respectively, exposed to Pb <strong>for</strong> 7 days at<br />

20,720 µg/L (Gupta and Chandra, 1994). Decreased soluble protein content has been observed<br />

in Scenedesmus obliquus exposed to Pb-nitrate or Pb-acetate at concentrations greater than<br />

30,000 µg/L, and in L. gibba at concentrations greater than 200,000 µg/L (Adam and<br />

Abdel-Basset, 1990; Miranda and Ilangovan, 1996). Lemna gibba also showed increased loss <strong>of</strong><br />

soluble starch at concentrations >200,000 µg/L (Miranda and Ilangovan, 1996). Under the<br />

conditions described previously (Gupta and Chandra, 1994), EC50 values <strong>for</strong> chlorophyll content<br />

were 14,504 and 18,648 µg/L <strong>for</strong> Vallisneria spiralis and Hydrilla verticillata, respectively<br />

(Gupta and Chandra, 1994). Effects to chlorophyll a content have been observed in<br />

Scenedesmus obliquus at Pb-nitrate and Pb-acetate concentrations >30,000 µg/L (Adam and<br />

Abdel-Basset, 1990).<br />

Summary <strong>of</strong> Toxic Effects Observed in Single-Species Bioassays<br />

Algae and aquatic plants have a wide range in sensitivity to the effects <strong>of</strong> Pb in water.<br />

Both groups <strong>of</strong> primary producers experience EC50 values <strong>for</strong> growth inhibition between<br />

approximately 1000 and >100,000 µg/L (Jampani, 1988; Gaur et al., 1994; Bilgrami and Kumar,<br />

AX7-181


1997). The most sensitive primary producers reported in the literature <strong>for</strong> effects to growth were<br />

Closterium acersoum and Azolla pinnata (Gaur et al., 1994; Bilgrami and Kumar, 1997). The<br />

least sensitive primary producers reported in the literature <strong>for</strong> effects to growth were<br />

Synechococcus aeruginosus and Lemna gibba (Jampani, 1988; Miranda and Ilangovan, 1996).<br />

Exposure to Pb in combination with other metals is generally less toxic to growth than exposure<br />

to lead alone. Studies have shown that lead adversely affects the metabolic processes <strong>of</strong> nitrate<br />

uptake, nitrogen fixation, ammonium uptake, and carbon fixation (Rai and Raizada, 1989). <strong>Lead</strong><br />

in combination with nickel or chromium produced synergistic effects <strong>for</strong> nitrate uptake,<br />

nitrogenase activities, ammonium uptake, and carbon fixation (Rai and Raizada, 1989).<br />

<strong>Lead</strong>s Effects on Primary Productivity<br />

<strong>Lead</strong> nitrate and Pb-acetate have been shown to have adverse effects on the primary<br />

productivity <strong>of</strong> aquatic plants in two water bodies in India (Jayaraj et al., 1992). One <strong>of</strong> the two<br />

water bodies was a freshwater tank that receives wastewater and supports a rich population <strong>of</strong><br />

hyacinths, and the other was a wastewater stabilization pond. Water quality characteristics in the<br />

freshwater tank were pH = 7.5, dissolved oxygen = 6 mg/L, and water hardness (CaCO3) =<br />

100 mg/L. Water quality characteristics in the wastewater pond were pH = 8.1, dissolved<br />

oxygen = 6.2 mg/L, and water hardness (CaCO3) = 160 mg/L (Jayaraj et al., 1992). <strong>Lead</strong> nitrate<br />

concentrations <strong>of</strong> 500, 5000, 10,000, 25,000, and 50,000 µg/L were combined with appropriate<br />

water samples in light and dark bottles and suspended in each <strong>of</strong> the water bodies <strong>for</strong> 4 h. The<br />

concentrations <strong>of</strong> Pb-acetate (5000, 10,000, 25,000, 50,000, and 100,000 µg/L) were applied in<br />

the same manner. The EC50 values were determined based on the concentration required to<br />

inhibit gross productivity (GP) and net productivity (NP) by 50% (Jayaraj et al., 1992). The<br />

results demonstrated that Pb-nitrate was more toxic to primary production than Pb-acetate.<br />

In the freshwater tank, Pb-nitrate EC50 values <strong>for</strong> GP and NP were 25,100 and 6310 µg/L,<br />

respectively, compared to Pb-acetate EC50 values <strong>of</strong> 50,100 and 28,200 µg/L <strong>for</strong> GP and NP,<br />

respectively (Jayaraj et al., 1992). In the stabilization pond, Pb-nitrate EC50 values <strong>for</strong> GP and<br />

NP were 31,600 and 28,200 µg/L, respectively, compared to Pb-acetate EC50 values <strong>of</strong> 79,400<br />

and 316 µg/L <strong>for</strong> GP and NP, respectively (Jayaraj et al., 1992). The higher toxicity reported in<br />

the freshwater tank was attributed to differences in species composition and diversity. The<br />

freshwater tank was dominated by water hyacinths that decreased the photic zone available <strong>for</strong><br />

AX7-182


photosynthesis and consumed a great deal <strong>of</strong> available nutrients. The stabilization pond had<br />

a rich nutrient budget, resulting in improved alga growth and species diversity (Jayaraj<br />

et al., 1992).<br />

AX7.2.4.3 Recent Studies on Effects <strong>of</strong> <strong>Lead</strong> on Consumers<br />

This section focuses on the effects <strong>of</strong> Pb to aquatic biota including invertebrates, fish, and<br />

other biota with an aquatic life stage (e.g., amphibians). It is not intended to be a comprehensive<br />

review <strong>of</strong> all research conducted. Rather, the intent is to illustrate the concentrations and effects<br />

<strong>of</strong> Pb on freshwater and marine aquatic species. Eisler (2000) provides an overview <strong>of</strong> much <strong>of</strong><br />

the recent available literature on the toxicity <strong>of</strong> Pb to fish and aquatic invertebrates. An<br />

extensive literature search was conducted using numerous electronic bibliographic and database<br />

services (e.g., DIALOG, <strong>EPA</strong> ECOTOX) and limited temporally from 1986 to present. This<br />

temporal limit was due to the availability <strong>of</strong> the <strong>EPA</strong> water quality criteria report <strong>for</strong> the<br />

protection <strong>of</strong> aquatic life, released in 1986 (U.S. Environmental Protection Agency, 1986b).<br />

Based on the results <strong>of</strong> the literature search and recent reviews <strong>of</strong> the toxicity <strong>of</strong> Pb (Eisler,<br />

2000), numerous studies have been published on the toxicity <strong>of</strong> Pb to aquatic consumers.<br />

Hardness, pH, temperature, and other factors are important considerations when characterizing<br />

the acute and chronic toxicity <strong>of</strong> lead (Besser et al., 2005) (Section AX7.2.3.5). However, many<br />

<strong>of</strong> the studies reviewed did not report critical in<strong>for</strong>mation on control mortality, water quality<br />

parameters, or statistical methods, making comparing effects between studies difficult. Studies<br />

reporting only physiological responses to Pb exposure (e.g., reduction <strong>of</strong> ALAD) are not<br />

discussed here, as this topic was covered more completely in Section AX7.2.3.4. This section<br />

provides a review <strong>of</strong> toxicity studies conducted with invertebrates, fish, and other aquatic<br />

organisms.<br />

Invertebrates<br />

Exposure <strong>of</strong> invertebrates to Pb can lead to adverse effects on reproduction, growth,<br />

survival, and metabolism (Eisler, 2000). The following presents in<strong>for</strong>mation on the toxicity <strong>of</strong><br />

Pb to invertebrates in fresh and marine waters.<br />

AX7-183


Freshwater Invertebrates<br />

Acute and chronic Pb toxicity data <strong>for</strong> freshwater invertebrates are summarized in Table<br />

AX7-2.4.1. As described in Section AX7.2.3.5, water hardness is a critical factor governing the<br />

solubility, bioavailability, and ultimately the toxicity <strong>of</strong> Pb. The acute and chronic toxicity <strong>of</strong> Pb<br />

increases with decreasing water hardness as Pb becomes more soluble and bioavailable to<br />

aquatic organisms. For example, Borgmann et al. (2005) examined the toxicity <strong>of</strong> 63 metals,<br />

including Pb, to Hyalella azteca at two levels <strong>of</strong> water hardness (s<strong>of</strong>t water hardness, 18 mg<br />

CaCO3/L; hard water, 124 mg CaCO3/L). <strong>Lead</strong> was 23 times more acutely toxic to H. azteca in<br />

s<strong>of</strong>t water than hard water. Besser et al. (2005) found that acute toxicity to H. azteca was also<br />

modified by water hardness.<br />

At a mean pH <strong>of</strong> 7.97 in s<strong>of</strong>t water (hardness (CaCO3) = 71 mg/L) mortality was >50%<br />

<strong>for</strong> H. azteca at a dissolved Pb concentration <strong>of</strong> 151 µg/L. The LOEC <strong>for</strong> survival in hard water<br />

(hardness (CaCO3) = 275 mg/L) at pH 8.27 was 192 µg/L as dissolved Pb and 466 µg/L as total<br />

Pb. Both waterborne and dietary Pb were found to contribute to reduced survival <strong>of</strong> H. azteca<br />

(Besser et al., 2005).<br />

Exposure duration may also play an important role in Pb toxicity in some species.<br />

For example, Kraak et al. (1994) reported that filtration in the freshwater mussel Dreissena<br />

polymorpha was adversely affected at significantly lower Pb concentrations over 10 weeks <strong>of</strong><br />

exposure than was the case after 48 h <strong>of</strong> exposure.<br />

The influence <strong>of</strong> pH on lead toxicity in freshwater invertebrates varies between<br />

invertebrate species. Over a 96-h exposure period, mortality increased with decreasing pH in the<br />

bivalve Pisidium casertanum, while pH-independent mortality was reported <strong>for</strong> gastropod and<br />

crustacean species under similar exposure conditions (Mackie, 1989). Cladocerans<br />

(Ceriodaphnia dubia), amphipods (H. azteca), and mayflies (Leptophlebia marginata) were also<br />

more sensitive to Pb toxicity at lower pH levels (Schubauer-Berigan et al., 1993; Gerhardt,<br />

1994). <strong>Lead</strong> was 100 times more toxic to the amphipod, Hyalella azteca, at a pH range <strong>of</strong> 5.0 to<br />

6.0 (Mackie, 1989) than at a pH range <strong>of</strong> 7.0 to 8.5 (Schubauer-Berigan et al., 1993).<br />

The physiology <strong>of</strong> an aquatic organism at certain life stages may be important when<br />

determining the toxicity <strong>of</strong> metals to test organisms. For example, Bodar et al. (1989) exposed<br />

early life stages <strong>of</strong> Daphnia magna to concentrations <strong>of</strong> Pb(NO3)2. The test medium had a pH<br />

<strong>of</strong> 8.3 ∀ 0.2, water hardness (CaCO3) <strong>of</strong> 150 mg/L, and temperature <strong>of</strong> 20 ∀ 1 ΕC. <strong>Lead</strong><br />

AX7-184


AX7-185<br />

Freshwater<br />

Species Chemical<br />

Cladoceran<br />

(Ceriodaphnia dubia)<br />

Worm<br />

(Lumbriculus variegatus)<br />

Amphipod<br />

(Hyalella azteca)<br />

Amphipod<br />

(Hyalella azteca)<br />

Amphipod<br />

(Hyalella azteca)<br />

Mayfly<br />

(Leptophlebia marginata)<br />

Mayfly<br />

(Leptophlebia marginata)<br />

Table AX7-2.4.1. Effects <strong>of</strong> <strong>Lead</strong> to Freshwater and Marine Invertebrates<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

Endpoint:<br />

Conc. (µg/L)*<br />

LC50:<br />

280<br />

>2,700<br />

>2,700<br />

LC50:<br />

>8,000<br />

>8,000<br />

>8,000<br />

LC50:<br />

5,400<br />

>5,400<br />

LC50:<br />

27 (20.1-36.4)<br />

LC50:<br />

60 (53.6-67.3)<br />

LC50:<br />

1090<br />

(400-133200)<br />

LC50:<br />

5000<br />

Duration <strong>of</strong><br />

Exposure Water Chemistry Test Type - Effect Reference<br />

48 h pH:<br />

6–6.5<br />

7–7.5<br />

8–8.5<br />

Hardness: 280-300 mg/L CaCO3<br />

96 h pH:<br />

6–6.5<br />

7–7.5<br />

8–8.5<br />

Hardness: 280-300 mg/L CaCO3<br />

96 h pH:<br />

6–6.5<br />

7–7.5<br />

8–8.5<br />

Hardness: 280-300 mg/L CaCO3<br />

8 days Hardness<br />

130 mg/L<br />

pH 7.8-8.6<br />

8 days Hardness<br />

130 mg/L<br />

pH 7.8–8.6<br />

96 h pH:<br />

4.5<br />

96 h pH<br />

7.0<br />

static-survival Schubauer-Berigan<br />

et al. (1993)<br />

static-survival Schubauer-Berigan<br />

et al. (1993)<br />

static-survival Schubauer-Berigan<br />

et al. (1993)<br />

renewal, 1-weekold<br />

amphipods<br />

renewal, 10- to 16week<br />

old<br />

amphipods<br />

MacLean et al.<br />

(1996)<br />

MacLean et al.<br />

(1996)<br />

acute - survival Gerhardt (1994)<br />

acute - survival Gerhardt (1994)


AX7-186<br />

Amphipod<br />

(Hyalella azteca)<br />

Species Chemical<br />

Bivalve<br />

(Pisidium compressum)<br />

Bivalve<br />

(Pisidium casertanum)<br />

Gastropod<br />

(Amnicola limosa)<br />

Mussel<br />

(Dreissena polymorpha)<br />

Mussel<br />

(Dreissena polymorpha)<br />

Amphipod<br />

(Hyalella azteca)<br />

Amphipod<br />

(Hyalella azteca)<br />

Table AX7-2.4.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> to Freshwater and Marine Invertebrates<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

lead<br />

nitrate<br />

Endpoint:<br />

Conc. (µg/L)*<br />

LC50:<br />

10<br />

21<br />

18<br />

LC50:<br />

38,000<br />

21,300<br />

11,400<br />

LC50:<br />

23,600<br />

23,500<br />

56,000<br />

LC50:<br />

10,300<br />

20,600<br />

9,500<br />

EC50:<br />

370<br />

91<br />

LT50:<br />

358<br />

LC50:<br />

4.8 (3.3 - 7.1)<br />

LC50:<br />

113 (101 -126)<br />

Duration <strong>of</strong><br />

Exposure Water Chemistry Test Type - Effect Reference<br />

96 h pH:<br />

5.0<br />

5.5<br />

6.0<br />

acute-survival Mackie (1989)<br />

96 h pH:<br />

3.5<br />

4.0<br />

4.5<br />

96 h pH:<br />

3.5<br />

4.0<br />

4.5<br />

96 h pH:<br />

3.5<br />

4.0<br />

4.5<br />

48 h<br />

10 wks<br />

pH = 7.9; Hardness = 150 mg<br />

CaCO3/L; Temp = 15 Ε C<br />

72 days pH = 7.9; Hardness = 150 mg<br />

CaCO3/L; Temp = 15 Ε C<br />

7 days pH = 7.37 - 8.27<br />

Hardness = 18 mg CaCO3/L<br />

DOC = 0.28 mg/L<br />

7 days pH = 8.21 - 8.46<br />

Hardness = 124 mg CaCO3/L;<br />

DOC = 1.1 mg/L<br />

acute- survival Mackie (1989)<br />

acute- survival Mackie (1989)<br />

acute- survival Mackie (1989)<br />

renewal - filtration Kraak et al. (1994)<br />

renewal - filtration Kraak et al. (1994)<br />

renewal - survival Borgmann et al.<br />

(2005)<br />

renewal - survival Borgmann et al.<br />

(2005)


AX7-187<br />

Species Chemical<br />

Mayfly<br />

(Leptophlebia marginata)<br />

Cladoceran<br />

(D. magna)<br />

Cladoceran<br />

(D. magna)<br />

Cladoceran<br />

(D.magna)<br />

Amphipod<br />

(Hyalella azteca)<br />

Tubificid worm<br />

(Tubifex tubifex)<br />

Marine<br />

Copepod<br />

(Amphiascus tenuiremis)<br />

Bivalve<br />

(Mytilus galloprovincialis)<br />

Table AX7-2.4.1 (cont’d). Effects <strong>of</strong> <strong>Lead</strong> to Freshwater and Marine Invertebrates<br />

lead<br />

chloride<br />

lead<br />

nitrate<br />

lead<br />

chloride<br />

lead<br />

chloride<br />

Endpoint:<br />

Conc. (Φg/L)*<br />

LC50:<br />

1090 (95% C.I. =<br />

133.2)<br />

>5000<br />

LC50:<br />

0.45<br />

NOEC:<br />

260<br />

NOEC:<br />

270<br />

lead LOEC:<br />

(Dissolved Pb)<br />

192<br />

(Total Pb) 466<br />

lead<br />

nitrate<br />

EC50:<br />

237 (183–316)<br />

142 (107–184)<br />

lead LC50: sediment<br />

2462 µg<br />

metal/dry<br />

sediment<br />

lead<br />

nitrate<br />

EC50 : 221<br />

(58.9–346.3)<br />

LOEC : 50<br />

* - Brackets after effect concentration are 95% confidence intervals.<br />

Duration <strong>of</strong><br />

Exposure Water Chemistry Test Type - Effect Reference<br />

96 h pH = 4.5 - 6.5;<br />

DOC - 21.6 mg Cl !1 ;<br />

Cond = 7.0 ΦS cm !1<br />

48 h pH = 8.3∀ 0.2<br />

Hardness (CaCO3) = 150 mg/L<br />

Temp= 20 Ε C<br />

renewal - survival Gerhardt (1994)<br />

static -<br />

embryogenesis<br />

12 to 21 d Not specified renewal -<br />

reproduction<br />

Bodar et al. (1989)<br />

Enserink et al.<br />

(1991)<br />

10 d Not specified renewal - growth Enserink et al.<br />

(1991)<br />

96 h pH = 8.27<br />

Hardness (CaCO3) = 275 mg/L<br />

Temp = 21.1 Ε C<br />

24 h<br />

48 h<br />

pH = 7.5–7.7<br />

Hardness = 245 mg/L<br />

Temp = 29.5–31 Ε C<br />

96 h pH = 7.7 ∀ 0.1<br />

Dissolved O2 -6.3 ∀ 0.3 mg/L<br />

Salinity – 32 ppt<br />

flow through -<br />

survival<br />

static -<br />

immobilization<br />

Besser et al. (2005)<br />

Khangarot (1991)<br />

Hagopian-Schlekat<br />

et al. (2001)<br />

artificial seawater embryogenesis Beiras and<br />

Albentosa (2003)


concentrations <strong>of</strong>


Fish<br />

The general symptoms <strong>of</strong> Pb toxicity in fish include production <strong>of</strong> excess mucus, lordosis,<br />

anemia, darkening <strong>of</strong> the dorsal tail region, degeneration <strong>of</strong> the caudal fin, destruction <strong>of</strong> spinal<br />

neurons, ALAD inhibition, growth inhibition, renal pathology, reproductive effects, growth<br />

inhibition, and mortality (Eisler, 2000). Toxicity in fish has been closely correlated with<br />

duration <strong>of</strong> Pb exposure and uptake (Eisler, 2000). The following presents in<strong>for</strong>mation on the<br />

toxicity <strong>of</strong> Pb to fish in fresh and marine waters. Table AX7-2.4.2 summarizes the effects <strong>of</strong> Pb<br />

on freshwater and marine fish.<br />

Freshwater Fish<br />

Many <strong>of</strong> the toxicity modifying factors described above and in Section AX7.2.3.5 (e.g.,<br />

pH, DOC) <strong>for</strong> invertebrates are also important modifying factors <strong>for</strong> Pb toxicity to fish species.<br />

The effects <strong>of</strong> pH on Pb bioavailability and subsequent toxicity have been well-studied (Sayer<br />

et al., 1989; Spry and Wiener, 1991; Schubauer-Berigan et al., 1993; Stouthart et al., 1994;<br />

MacDonald et al., 2002; Rogers and Wood, 2003). Schubauer-Berigan et al. (1993) exposed<br />

fathead minnow to Pb-chloride over 96 hours. The reported LC50 ranged from 810 to<br />

>5400 µg/L at pH 6 to 6.5 and pH 7 to 8.5, respectively.<br />

Water hardness also has a strong influence on the effects <strong>of</strong> lead to fish. Chronic<br />

exposure <strong>of</strong> rainbow trout fry to Pb in s<strong>of</strong>t water resulted in spinal de<strong>for</strong>mities at 71 to 146 µg/L<br />

after 2 months <strong>of</strong> exposure (Sauter et al., 1976) or 13.2 to 27 µg/L (Davies and Everhart, 1973;<br />

Davies et al., 1976), after 19 months <strong>of</strong> exposure. When exposed to Pb in hard water, only 0 and<br />

10% <strong>of</strong> the trout (Oncorhynchus mykiss) developed spinal de<strong>for</strong>mities at measured Pb<br />

concentrations <strong>of</strong> 190 and 380 µg/L, respectively. In s<strong>of</strong>t water, 44 and 97% <strong>of</strong> the trout<br />

developed spinal de<strong>for</strong>mities at concentrations <strong>of</strong> 31 and 62 µg/L, respectively (Davies et al.,<br />

1976). The maximum acceptable toxicant concentration (MATC) <strong>for</strong> rainbow trout fry in s<strong>of</strong>t<br />

water was 4.1 to 7.6 µg/L (Davies et al., 1976), while the MATC <strong>for</strong> brook trout was 58 to<br />

119 µg/L (Holcombe et al., 1976). Histological reproductive abnormalities were noted in mature<br />

male rainbow trout at 10 µg/L Pb-nitrate (Ruby et al., 1993).<br />

Schwartz et al. (2004) examined the influence <strong>of</strong> NOM on Pb toxicity to rainbow trout<br />

exposed <strong>for</strong> 96 h in a static system. The pH <strong>of</strong> the exposure system ranged between 6.5 and 7.0,<br />

temperature was maintained between 9 and 11 ΕC, and Pb was added as PbCl2. NOM from a<br />

AX7-189


AX7-190<br />

Freshwater<br />

Species Chemical<br />

Fathead minnow<br />

(Pimephales promelas)<br />

Rainbow trout - mature<br />

males<br />

(Oncorhynchus mykiss)<br />

Fathead minnow<br />

(Pimephales promelas)<br />

Rainbow trout – Juvenile<br />

(Oncorhynchus mykiss)<br />

Common carp<br />

(Cyprinus carpio)<br />

lead<br />

chloride<br />

lead<br />

nitrate<br />

lead<br />

acetate<br />

lead<br />

nitrate<br />

not<br />

reported<br />

Table AX7-2.4.2. Effects <strong>of</strong> Pb to Freshwater and Marine Fish<br />

LC50:<br />

810<br />

>5,400<br />

>5,400<br />

Endpoint:<br />

Conc. (Φg/L)<br />

Reproductive effects:<br />

10<br />

Reproductive Effects:<br />

500<br />

LC50: 1000<br />

(800 - 1400)<br />

LC50:<br />

6.5 cm fish – 1030<br />

3.5 cm fish – 300<br />

Duration <strong>of</strong><br />

Exposure Water Chemistry Comments Reference<br />

96 h pH:<br />

6–6.5<br />

7–7.5<br />

8–8.5<br />

Hardness: 280-300<br />

mg/L CaCO3<br />

12 days Hardness 128 mg/L<br />

CaCO3<br />

29 days pH:<br />

7.5–8.5;<br />

Hardness 130 mg/L<br />

CaCO3;<br />

22–25 Ε C<br />

(Pb 95% soluble)<br />

96 h pH:<br />

7.9–8.0<br />

DOC = 3 mg/L<br />

Hardness (CaCO3) =<br />

140 mg/L<br />

96 h pH:<br />

7.1<br />

Temperature–15 Ε C<br />

Oxygen sat. 6.4 mg/L<br />

static, measured Schubauer-Berigan<br />

et al. (1993)<br />

Decreased<br />

spermatocyte<br />

development<br />

Fewer viable eggs<br />

produced, testicular<br />

damage<br />

Ruby et al. (1993)<br />

Weber (1993)<br />

Flow through - Survival Rogers and Wood<br />

(2003)<br />

static-renewal -<br />

Survival<br />

Alam and Maughan<br />

(1995)


number <strong>of</strong> U.S. rivers and lakes was then added to the test system, and the LT50 was reported.<br />

NOM was found to reduce the toxic effects <strong>of</strong> Pb to rainbow trout.<br />

Fish size is an important variable in determining the adverse effects <strong>of</strong> Pb. Alam and<br />

Maughan (1995) exposed two different sizes <strong>of</strong> common carp (Cyprinus carpio) to Pb<br />

concentrations to observed effects on carp mortality. Water chemistry parameters were reported<br />

(pH = 7.1; temperature = 20 ΕC). Smaller fish (3.5 cm) were found to be more sensitive to Pb<br />

than were larger fish (6.5 cm). The reported LC50s were 0.44 mg/L and 1.03 mg/L, respectively.<br />

Marine Fish<br />

There were no studies available that examined the toxicity <strong>of</strong> Pb to marine fish species <strong>for</strong><br />

the time period examined (1986 to present). However, Eisler (2000) reviewed available research<br />

on Pb toxicity to marine species and reported studies done prior to 1986. Acute toxicity values<br />

ranged from 50 µg/L to 300,000 µg/L in plaice (Pleuronectes platessa) exposed to organic and<br />

inorganic <strong>for</strong>ms <strong>of</strong> Pb (Eisler, 2000). Organolead compounds (e.g., tetramethyl Pb, tetraethyl Pb,<br />

triethyl Pb, diethyl Pb) were generally more toxic to plaice than inorganic Pb (Maddock and<br />

Taylor, 1980).<br />

Other Aquatic Biota<br />

A paucity <strong>of</strong> data exist on the effects <strong>of</strong> Pb to growth, reproduction, and survival <strong>of</strong><br />

aquatic stages <strong>of</strong> frogs and turtles. Rice et al. (1999) exposed frog larvae (Rana catesbeiana) to<br />

780 µg Pb/L and two oxygen concentrations (3.5 or 7.85 mg/L) <strong>for</strong> 7 days (Table AX7-2.4.3).<br />

Exposure conditions included water hardness <strong>of</strong> 233 to 244 mg CaCO3/L, pH from 7.85 to 7.9,<br />

and temperature at 23 ΕC. Frog larvae were found to display little to no activity in the low<br />

oxygen and high Pb treatment. Hypoxia-like behavior was exhibited in larvae exposed to both<br />

low and high oxygen concentrations and high Pb. There<strong>for</strong>e, larvae <strong>of</strong> R. catesbeiana showed<br />

sensitivity to Pb and responded with hypoxia-like behavior. Additionally, the larvae in the Pb<br />

treatment were found to have lost body mass relative to controls and the other treatments. Rice<br />

et al. (1999) suggested that the decrease in mass likely indicated the beginning <strong>of</strong> a period <strong>of</strong><br />

reduced growth rate. Larvae exposed <strong>for</strong> longer periods (>4 weeks) were smaller and<br />

metamorphosed later compared to unexposed individuals.<br />

AX7-191


AX7-192<br />

Species Chemical<br />

Frogs<br />

(Rana ridibunda)<br />

Frogs<br />

(Bufo arenarum)<br />

Frogs<br />

(Rana catesbeiana)<br />

Turtle Hatchlings<br />

(Trachemys scripta)<br />

Table AX7-2.4.3. Nonlethal Effects in Amphibians<br />

Endpoint:<br />

Concentration<br />

lead nitrate Biochemical effects:<br />

14,000 µg/L<br />

Mortality:<br />

16 mg Pb2+/L<br />

Hypoxia-like behavior:<br />

780 µg/L<br />

lead acetate NOEL: 100 µg/g<br />

(Survival and<br />

behavior)<br />

Duration <strong>of</strong><br />

Exposure<br />

Water Chemistry Comments Reference<br />

30 days Not specified Hepatic ALAD decreased by<br />

90%<br />

5 days Not specified Effects reported include erratic<br />

swimming, loss <strong>of</strong> equilibrium<br />

7 days O2 = 3.5-7.85 mg/L<br />

pH = 7.85-7.9<br />

Temp = 23 ΕC<br />

CaCO3 = 233-244<br />

mg/L<br />

Vogiatzis and<br />

Loumbourdis (1999)<br />

Herkovits and Perez-Coll<br />

(1991)<br />

Larvae used Rice et al. (1999)<br />

4 weeks N/A Exposure via single injection Burger et al. (1998)


Herkovits and Pérez-Coll (1991) examined Pb toxicity to amphibian larvae (Bufo<br />

arenarum). Larvae (n = 50) were exposed <strong>for</strong> up to 120 h at two Pb concentrations, 8 mg Pb 2+ /L<br />

and 16 mg Pb 2+ /L. Relative to controls, the 8 mg Pb 2+ /L treatment group exhibited 40%<br />

mortality and the 16 mg Pb 2+ /L group 60% mortality after 120 h (p < 0.05). The authors reported<br />

behavioral effects, erratic swimming, and loss <strong>of</strong> equilibrium during the tests, symptoms that are<br />

consistent with the action <strong>of</strong> Pb on the central and peripheral nervous systems (Rice et al., 1999).<br />

Behavior (i.e., righting, body turnover, seeking cover), growth, and survival <strong>of</strong> hatchling<br />

slider turtles (Trachemys scripta) exposed to Pb-acetate were investigated in one study (Burger<br />

et al., 1998). In the first part <strong>of</strong> the study, 6-month-old hatchlings received single Pb-acetate<br />

injections at 50 or 100 µg/g body weight (bw). In the second part <strong>of</strong> the study, 3-week-old<br />

turtles were injected once with doses <strong>of</strong> 250, 1000 or 2500 µg/g bw. There were no differences<br />

in survival, growth, or behavior <strong>for</strong> hatchlings in the first study, however, several effects were<br />

reported from the second part <strong>of</strong> the study at doses in the range <strong>of</strong> 250 to 2,500 µg/g bw. As the<br />

dose increased, so did the plastron length (i.e., ventral section <strong>of</strong> the shell), carapace length, and<br />

weight. The highest dose group had the lowest survival rate with an LD50 <strong>of</strong> 500 µg/g bw.<br />

Behavioral effects included slower times <strong>of</strong> righting behavior and seeking cover. The authors<br />

suggested a NOEL <strong>of</strong> 100 µg/g bw <strong>for</strong> slider turtles <strong>for</strong> survival and behavior.<br />

AX7.2.4.4 Recent Studies on Effects <strong>of</strong> <strong>Lead</strong> on Decomposers<br />

In this section, decomposers are defined as being bacteria and other microorganisms.<br />

Many invertebrates are also potentially considered decomposers, but the effects <strong>of</strong> Pb to<br />

invertebrates have been described in previous sections. There were no toxicity studies located on<br />

the effects <strong>of</strong> Pb to aquatic decomposers in the time period <strong>of</strong> interest.<br />

AX7.2.4.5 Summary<br />

<strong>Lead</strong> in all its <strong>for</strong>ms is known to cause adverse effects in aquatic organisms (Eisler, 2000).<br />

Effects to algal growth have been observed at b concentrations ranging from 100 to<br />

200,000 µg/L. Clinical signs <strong>of</strong> Pb toxicity in plants include the de<strong>for</strong>mation and disintegration<br />

<strong>of</strong> algae cells and a shortened exponential growth phase. Other effects <strong>of</strong> Pb include a blocking<br />

<strong>of</strong> the pathways that lead to pigment synthesis, thus affecting photosynthesis, cell cycle and<br />

division, and ultimately resulting in death. The toxicity <strong>of</strong> Pb to macrophyte growth has been<br />

AX7-193


studied using Spirodela polyrhiza, Azolla pinnata, and Lemna gibba. Test durations ranged from<br />

4 to 25 days and test concentrations ranged between 49.7 and 500,000 µg/L.<br />

Waterborne Pb is highly toxic to aquatic organisms, with toxicity varying with the species<br />

and life stage tested, duration <strong>of</strong> exposure, <strong>for</strong>m <strong>of</strong> Pb tested, and water quality characteristics.<br />

Among the species tested, aquatic invertebrates, such as amphipods and water fleas, were the<br />

most sensitive to the effects <strong>of</strong> Pb, with adverse effects being reported as low as 0.45 µg/L.<br />

Effects concentrations <strong>for</strong> aquatic invertebrates were found to range from 0.45 to 8000 µg/L.<br />

Freshwater fish demonstrated adverse effects at concentrations ranging from 10 to >5400 µg/L,<br />

depending generally upon water quality parameters. Amphibians tend to be relatively Pb tolerant<br />

(Eisler, 2000); however, they may exhibit decreased enzyme activity (e.g., ALAD reduction) and<br />

changes in behavior (e.g., hypoxia response behavior). <strong>Lead</strong> tends to be more toxic with longer-<br />

term exposures.<br />

The primary focus <strong>of</strong> this section was on effects at the individual level <strong>of</strong> organization.<br />

This narrow focus is primarily due to a lack <strong>of</strong> in<strong>for</strong>mation on the effects <strong>of</strong> lead on higher levels<br />

<strong>of</strong> organization (e.g., populations, communities, and ecosystems). The impact <strong>of</strong> lead at higher<br />

levels <strong>of</strong> biological organization should be considered in future reviews <strong>of</strong> lead toxicity.<br />

In considering these higher levels <strong>of</strong> organization, cause-effect models and relationships that<br />

examine the roles <strong>of</strong> life history strategy and optimal <strong>for</strong>aging theory, community processes and<br />

associated theory, and ecosystem processes and the influences <strong>of</strong> redundancy/interactions should<br />

be taken into account.<br />

AX7.2.5 Effects <strong>of</strong> <strong>Lead</strong> on Natural Aquatic Ecosystems<br />

Introduction<br />

As discussed previously, lead exposure may adversely affect organisms at different levels<br />

<strong>of</strong> organization, i.e., individual organisms, populations, communities, or ecosystems. Generally,<br />

however, there is insufficient in<strong>for</strong>mation available <strong>for</strong> single materials in controlled studies to<br />

permit evaluation <strong>of</strong> specific impacts on higher levels <strong>of</strong> organization (beyond the individual<br />

organism). Potential effects at the population level or higher are, <strong>of</strong> necessity, extrapolated from<br />

individual level studies. Available population, community, or ecosystem level studies are<br />

typically conducted at sites that have been contaminated or adversely affected by multiple<br />

stressors (several chemicals alone or combined with physical or biological stressors). There<strong>for</strong>e,<br />

AX7-194


the best documented links between lead and effects on the environment are with effects on<br />

individual organisms.<br />

This section discusses the effects <strong>of</strong> Pb on natural aquatic ecosystems. Such effects<br />

include changes in species composition and richness, ecosystem function, and energy flow due to<br />

Pb stress. The <strong>for</strong>mat <strong>of</strong> this section generally follows a conceptual framework <strong>for</strong> discussing<br />

the effects <strong>of</strong> a stressor such as Pb on an ecosystem. This conceptual framework was developed<br />

by the <strong>EPA</strong> Science Advisory Board (Young and Sanzone, 2002). The essential attributes used<br />

to describe ecological condition include landscape condition, biotic condition, chemical and<br />

physical characteristics, ecological processes, hydrology and geomorphology and natural<br />

disturbance regimes. The majority <strong>of</strong> the published literature pertaining to Pb and aquatic<br />

ecosystems focuses on the biotic condition, one <strong>of</strong> several essential attributes <strong>of</strong> an ecosystem as<br />

described in Young and Sanzone (2002). For the biotic condition, the SAB framework identifies<br />

community extent, community composition, trophic structure, community dynamics, and<br />

physical structure as factors <strong>for</strong> assessing ecosystem health. Other factors <strong>for</strong> assessing the<br />

biotic condition such as effects <strong>of</strong> Pb on organs, species, populations, and organism conditions<br />

(e.g., physiological status) were discussed in Sections AX7.2.3 and AX7.2.4.<br />

For natural aquatic ecosystems, the focus <strong>of</strong> study in the general literature has been on<br />

evaluating ecological stress where the sources <strong>of</strong> Pb were from urban and mining effluents rather<br />

than atmospheric deposition (Poulton et al., 1995; Deacon et al., 2001; Mucha et al., 2003). The<br />

atmospheric deposition <strong>of</strong> Pb in remote lakes has been evaluated; however, the direct effects <strong>of</strong><br />

Pb on aquatic ecosystems was not evaluated in many cases (Larsen, 1983; Köck et al., 1996;<br />

Allen-Gil et al., 1997; Outridge, 1999; Lotter et al., 2002). In other studies, although Pb<br />

deposition was studied, the effects <strong>of</strong> acid deposition on aquatic life were the focus <strong>of</strong> the study<br />

and perceived to be more relevant (Mannio, 2001; Nyberg et al., 2001). Finally, the effects <strong>of</strong><br />

Pb, other metals, and acidification on phytoplankton have only been inferred based on the<br />

paleolimnolical record (Tolonen and Jaakkola, 1983; Rybak et al., 1989). The statistical<br />

methods used when evaluating the effects <strong>of</strong> Pb on aquatic ecosystems are important, as more<br />

than one variable may be related to the observed effect. Studied variables include water<br />

hardness, pH, temperature, and physical factors such as embeddedness, dominant substrate, and<br />

velocity. In most cases, single variable statistical techniques were used to evaluate the data.<br />

AX7-195


However, in other cases multivariate techniques were used. There<strong>for</strong>e, where appropriate, some<br />

detail on the statistical methods used is presented.<br />

Although most <strong>of</strong> the available studies discussed in this section focus on the biotic<br />

condition, one case study examining multiple components <strong>of</strong> the <strong>EPA</strong> conceptual framework is<br />

also included. The remainder <strong>of</strong> this section describes the effects <strong>of</strong> Pb on the biotic condition.<br />

AX7.2.5.1 Case Study: Coeur d’Alene River Watershed<br />

The Coeur d’Alene River watershed is an area <strong>of</strong> Idaho impacted by Pb and other metals<br />

from historic mining waste releases. Maret et al. (2003) examined several ecological<br />

components to determine any negative associations with metals and the watershed communities.<br />

The variables examined and associated ecological conditions are presented in Table AX7-2.5.1.<br />

In addition to measurements <strong>of</strong> non-metal variables (e.g., dissolved oxygen levels, water<br />

temperature and pH, embeddedness), Cd, Pb, and Zn levels were also compared in affected sites<br />

versus reference sites.<br />

Some <strong>of</strong> the above non-metal variables are important to macroinvertebrate communities.<br />

For example, a stream with highly embedded substrate can have a lower number <strong>of</strong> individuals<br />

within a species or a different species composition compared to a stream with less embeddedness<br />

(Waters, 1995). Macroinvertebrates from the Ephemeroptera (mayflies), Plecoptera (stoneflies),<br />

and Trichoptera (caddisflies) (EPT) group inhabit the surface <strong>of</strong> cobble and the interstitial spaces<br />

between and underneath cobble. When substrate is embedded, these interstitial spaces are filled,<br />

leaving less habitat space <strong>for</strong> EPT taxa. In another example, water temperature is important;<br />

some macroinvertebrates (e.g., stoneflies) are usually only found in cooler water (Harper and<br />

Stewart, 1984).<br />

Of the variables examined only metal concentrations, mine density, site elevation, and<br />

water temperature were significantly different between reference and mine-affected sites.<br />

A Mann-Whitney t-test was used to evaluate statistical differences between reference and<br />

test sites <strong>for</strong> physical and water quality parameters, while Spearman’s rank correlation matrices<br />

were used to compare all possible response and explanatory variables. <strong>Lead</strong> concentrations were<br />

significantly correlated with the number <strong>of</strong> mines in proximity to the watershed. <strong>Lead</strong><br />

concentrations in sediment and water were strongly correlated to Pb levels in whole caddisflies,<br />

r 2 = 0.90 and 0.63, respectively. Furthermore, mine density was significantly correlated to Pb in<br />

AX7-196


Table AX7-2.5.1. Ecological Attributed Studies by Maret et al. (2003)<br />

in the Coeur d’Alene Watershed<br />

Ecological Attribute Subcategory Measure<br />

Landscape condition Areal extent<br />

landscape pattern<br />

Biotic Condition Organism condition<br />

population structure/<br />

dynamics<br />

Chemical/physical<br />

characteristics<br />

Chemical/physical<br />

parameters<br />

AX7-197<br />

Basin area (km 2 )<br />

Production mine density/km 2<br />

Ecological processes — None measured<br />

Hydrology/geomorphology Channel morphology<br />

and distribution<br />

Caddisfly tissue concentrations (mg/kg)<br />

Number <strong>of</strong> EPT taxa<br />

Density <strong>of</strong> EPT individuals (no./m 2 )<br />

Dissolved oxygen (mg/L)<br />

Specific conductance (µS/cm)<br />

Water temperature (E ΕC)<br />

pH<br />

Water hardness (mg/L)<br />

Total NO3 (mg/L)<br />

Total P (mg/L)<br />

Dissolved NH 3 (mg/L)<br />

Sediment Cd, Pb, Zn (mg/kg)<br />

Dissolved Cd, Pb, Zn in water (mg/L)<br />

Site elevation (m)<br />

Stream gradient (%)<br />

Stream discharge (m 3 /s)<br />

Stream width (m)<br />

Stream depth (m)<br />

Open canopy (%)<br />

Stream velocity (m/s)<br />

Embeddedness (%)<br />

Dominant substrate (mm)<br />

Natural disturbance regimes — None measured<br />

tissue, r 2 = 0.64. Although temperature was significantly different between reference and<br />

mine-affected sites, temperature conditions were concluded to be non-limiting to aquatic life.<br />

For example, reference and mine-affected sites had at least 15 and 13 obligate cold-water taxa,<br />

respectively.<br />

A significant negative correlation between Pb in the water column (0.5 to 30 µg/L<br />

dissolved) and total taxa richness, EPT taxa richness, and the number <strong>of</strong> metal-sensitive mayfly


species was observed. Similar, significant negative correlations were found between sediment<br />

Pb levels (132 to 6252 µg/g) and the same macroinvertebrate community metrics and caddisfly<br />

tissue levels. Negative correlations were also found between Cd and Zn in the water and<br />

sediment and the macroinvertebrate community metrics. In an analysis <strong>of</strong> cumulative toxicity,<br />

Pb was judged to be the most significant metal in sediment related to the cumulative toxicity<br />

measured. This study provided multiple lines <strong>of</strong> evidence (i.e., mine density, metal<br />

concentrations, bioaccumulation in caddisfly tissue and benthic invertebrate assemblage<br />

structure) <strong>of</strong> the negative impacts <strong>of</strong> mining in the Coeur d’Alene River, suggesting that Pb (and<br />

other metals) were primary contributors to the effects observed in the Coeur d’Alene River<br />

watershed (Maret et al., 2003).<br />

AX7.2.5.2 Biotic Condition<br />

In an evaluation <strong>of</strong> the biotic condition, the SAB framework described by Young and<br />

Sanzone (2002) identifies community extent, community composition, trophic structure,<br />

community dynamics, and physical structure as essential ecological attributes <strong>for</strong> assessing<br />

ecosystem health. The following two sections describe the effects <strong>of</strong> Pb on community<br />

composition, community dynamics, and trophic structure. To date, no available studies were<br />

located on the effects <strong>of</strong> Pb on physical structure (e.g., change in riparian tree canopy height,<br />

ecosystem succession).<br />

Ecosystems and Communities, Community Composition<br />

To measure community composition, an inventory <strong>of</strong> the species/taxa found in the<br />

ecological system must be conducted. According the SAB framework, useful measures <strong>of</strong><br />

composition include the total number <strong>of</strong> species or taxonomic units, their relative abundance,<br />

presence and abundance <strong>of</strong> native and non-native species, and in<strong>for</strong>mation on the presence and<br />

abundance <strong>of</strong> focal or special interest species (Young and Sanzone, 2002). Focal or special<br />

species <strong>of</strong> interest can be those that play a critical role in ecosystem processes such as flows <strong>of</strong><br />

materials or energy within complex food-webs (Young and Sanzone, 2002). Community<br />

composition as assessed in Pb studies has included the following measures.<br />

AX7-198


• Changes in energy flow or nutrient cycling:<br />

o Increased or decreased respiration or biomass<br />

o Increased or decreased turnover/cycling <strong>of</strong> nutrients<br />

• Changes in community structure:<br />

o Reduced species abundance (i.e., the total number <strong>of</strong> individuals <strong>of</strong> a species within<br />

a given area or community)<br />

o Reduced species richness (i.e., the number <strong>of</strong> different species present in<br />

a community)<br />

o Reduced species diversity (i.e., a measure <strong>of</strong> both species abundance and species<br />

richness)<br />

Investigators have evaluated the effects <strong>of</strong> Pb on aquatic communities through microcosm<br />

and mesocosm studies in natural aquatic systems. Field studies in the general literature have<br />

focused on natural systems that were affected by metal stress from various anthropogenic<br />

sources. In most <strong>of</strong> those natural systems, the sources evaluated were from direct mining waste<br />

inputs, rather than atmospheric deposition, <strong>of</strong> Pb. Studies published since the 1986 <strong>Lead</strong> AQCD<br />

(U.S. Environmental Protection Agency, 1986a) that describe the effects <strong>of</strong> Pb on natural aquatic<br />

ecosystems are presented below and summarized in Table AX7-2.5.2. Studies included here<br />

evaluated the effects <strong>of</strong> Pb on watersheds, landscapes, aquatic ecosystems, aquatic communities,<br />

biodiversity, lakes, rivers, streams, estuaries, wetlands, and species interaction.<br />

Aquatic Microcosm Studies<br />

The examination <strong>of</strong> simulated aquatic ecosystems (i.e., microcosms) provides limited<br />

in<strong>for</strong>mation on the effects <strong>of</strong> pollutants on natural systems. Microcosm studies typically focus<br />

on only a few aspects <strong>of</strong> the natural system and do not incorporate all <strong>of</strong> the ecological,<br />

chemical, or biological interactions. Nevertheless, a few microcosm studies have been<br />

conducted that indicate potential effects <strong>of</strong> Pb on the community structure <strong>of</strong> aquatic ecosystems.<br />

Fernandez-Leborans and Antonio-García (1988) evaluated the effect <strong>of</strong> Pb on a natural<br />

community <strong>of</strong> freshwater protozoans in simulated aquatic ecosystems and found a reduction in<br />

the abundance and composition <strong>of</strong> protozoan species with increasing Pb concentrations (0.05 to<br />

1.0 mg/L) compared to controls. Studies with marine protozoan communities in laboratory<br />

microcosms indicated that waterborne Pb exposure reduced protozoan abundance, biomass, and<br />

AX7-199


AX7-200<br />

Table AX7-2.5.2. Essential Ecological Attributes <strong>for</strong> Natural Aquatic Ecosystems Affected by <strong>Lead</strong><br />

Category Species<br />

Biotic Condition<br />

Ecosystems and<br />

Communities-<br />

Community<br />

Composition<br />

Condition<br />

Measures<br />

Protozoan community Reduced species<br />

abundance and<br />

diversity<br />

Protozoan community Reduced species<br />

abundance<br />

Protist community Reduced species<br />

abundance and<br />

diversity<br />

Exposure<br />

Medium Location<br />

Exposure<br />

Concentrations<br />

Other<br />

Metals<br />

Present Reference<br />

Marine water Laboratory microcosm 0.02– 0.05 mg/L N Fernandez-<br />

Leborans and<br />

Novillo (1992)<br />

Freshwater<br />

water<br />

Mei<strong>of</strong>auna community Reduced abundance Marine<br />

sediment<br />

Algal community Increased respiration Freshwater Domestic water<br />

stabilization pond<br />

Algal community Decreased primary<br />

productivity<br />

Meiobenthic<br />

community<br />

(primarily nematodes)<br />

Reduced species<br />

abundance<br />

No effect on<br />

abundance<br />

Laboratory microcosm 0.05–1 mg/L N Fernandez-<br />

Leborans and<br />

Antonio-García<br />

(1988)<br />

Marine water Laboratory microcosm 1 mg/L N Fernandez-<br />

Leborans and<br />

Novillo (1994)<br />

Laboratory microcosm 177 mg/kg dw Y Millward et al.<br />

(2001)<br />

Freshwater Sharana Basaveshwara<br />

Tank, India<br />

Marine<br />

sediment<br />

Laboratory microcosm 1343 mg/kg dw<br />

1580 mg/kg dw<br />

25–80 mg/L ? Jayaraj et al. (1992)<br />

6–32 mg/L ? Jayaraj et al. (1992)<br />

N Austen and<br />

McEvoy (1997)


AX7-201<br />

Table AX7-2.5.2 (cont’d). Essential Ecological Attributes <strong>for</strong> Natural Aquatic Ecosystems Affected by <strong>Lead</strong><br />

Category Species<br />

Macroinvertebrate<br />

community<br />

Macroinvertebrate<br />

community<br />

Macroinvertebrate<br />

community<br />

Fish, crustacean and<br />

macroinvertebrate<br />

community<br />

Condition<br />

Measures<br />

Lower total<br />

abundance, decreased<br />

taxa, and EPT<br />

richness, larger<br />

percentage <strong>of</strong> tolerant<br />

species <strong>of</strong> benthic<br />

macroinvertebrates.<br />

Negatively correlated<br />

with species richness<br />

and diversity indices<br />

Reduced species<br />

abundance<br />

Correlation with<br />

changes in species<br />

abundance and<br />

distribution<br />

Chironomid community Reduced chironomid<br />

richness<br />

Macroinvertebrate<br />

community<br />

Macroinvertebrate<br />

community<br />

<strong>Lead</strong> in tissues<br />

negatively correlated<br />

with taxa richness,<br />

EPT richness,<br />

chironomid richness,<br />

and species density.<br />

<strong>Lead</strong> in tissues<br />

negatively correlated<br />

with EPT richness<br />

and abundance.<br />

Exposure<br />

Medium Location<br />

Freshwater<br />

and sediment<br />

Estuary<br />

sediment<br />

Freshwater<br />

sediment<br />

Marine<br />

Sediment<br />

Whole<br />

organism<br />

residue<br />

Whole<br />

organism<br />

residue<br />

Bi<strong>of</strong>ilm<br />

residues<br />

Mining sites in the<br />

Upper Colorado Basin<br />

Exposure<br />

Concentrations<br />


AX7-202<br />

Table AX7-2.5.2 (cont’d). Essential Ecological Attributes <strong>for</strong> Natural Aquatic Ecosystems Affected by <strong>Lead</strong><br />

Category Species Condition Measures<br />

Ecosystems and<br />

Communities-<br />

Community<br />

Dynamics and<br />

Trophic Structure<br />

Macroinvertebrate<br />

Community<br />

<strong>Lead</strong> in tissues and<br />

sediment not correlated<br />

to diversity and<br />

richness<br />

Fish Community <strong>Lead</strong> in tissues and<br />

sediment not correlated<br />

to diversity and<br />

richness<br />

Snails and tadpoles <strong>Lead</strong> affected predatorprey<br />

interactions<br />

Snails and caddisflies No avoidance <strong>of</strong><br />

predator by snail.<br />

Caddisfly did respond<br />

to predator<br />

Fathead minnow Feeding behavior<br />

altered<br />

Exposure<br />

Medium Location<br />

Sediment<br />

and whole<br />

organism<br />

residue<br />

Sediment<br />

and whole<br />

organism<br />

residue<br />

Aquashicola Creek<br />

tributaries, Palmerton,<br />

PA<br />

Aquashicola Creek<br />

tributaries, Palmerton,<br />

PA<br />

Sediment Outdoor miniecosystems<br />

Water Field microcosm <strong>for</strong><br />

snail; in-stream<br />

disturbance <strong>for</strong><br />

caddisfly<br />

Exposure<br />

Concentrations<br />

7.5–59.5 mg/kg dw<br />

(sediment)<br />

0.25-6.03 mg/kg dw<br />

(macroinvertebrates)<br />

7.5–59.5 mg/kg dw<br />

(sediment)<br />

0.1-0.86 mg/kg dw<br />

(fish)<br />

Other<br />

Metals<br />

Present Reference<br />

Y Carline and Jobsis<br />

(1993)<br />

Y Carline and Jobsis<br />

(1993)<br />

Not cited Y Lefcort et al. (1999)<br />

27.7–277.6 mg/kg<br />

dw (snail tissue)<br />

223–13,507 mg/kg<br />

dw (caddisfly tissue)<br />

Y Lefcort et al. (2000)<br />

Water Laboratory microcosm 0.5–1.0 mg/L N Weber (1996)<br />

American toad No avoidance <strong>of</strong> lead Water Laboratory microcosm 0.5–1.0 mg/L N Steele et al. (1991)<br />

Mummichog Feeding behavior<br />

altered and predator<br />

avoidance affected<br />

Water Laboratory 0.3–1.0 mg/L N Weis and Weis<br />

(1998)


diversity at concentrations <strong>of</strong> 0.02 to 1.0 mg/L Pb (Fernandez-Leborans and Novillo,<br />

1992, 1994).<br />

Austen and McEvoy (1997) studied the effects <strong>of</strong> Pb on an estuarine meiobenthic<br />

community (mainly nematodes) in a microcosm setting using sediment samples collected<br />

<strong>of</strong>fshore from England. A multivariate analysis <strong>of</strong> similarities (ANOSIM) test with square root-<br />

trans<strong>for</strong>med data was used to evaluate differences between treatments and controls. <strong>Lead</strong> was<br />

found to significantly affect species abundance at 1343 mg/kg dw relative to a control at<br />

56 mg/kg dw, but no significant adverse effects were observed at the highest dose tested,<br />

1580 mg/kg dw. The authors did not attempt to explain why the 1580 mg/kg dw dose was not<br />

significant while the 1343 mg/kg dw dose was. None <strong>of</strong> the Pb exposures were significantly<br />

different than the controls based on separate univariate tests <strong>of</strong> abundance, richness, and<br />

diversity. There were no other confounding metals in the Pb tests, as the experiments were with<br />

a single metal dose. In one other mesocosm study, the effects <strong>of</strong> a mixture <strong>of</strong> metals (Cu, Cd,<br />

Pb, Hg, and Zn) on a salt marsh mei<strong>of</strong>aunal community were evaluated (Millward et al., 2001).<br />

After 30-days exposure, significant reductions in copepod, gastropod, and bivalve<br />

abundances were observed at the highest Pb exposure concentration, 177 mg/kg dw. Ostracods<br />

and nematodes were not affected. The authors believed that the response <strong>of</strong> the mei<strong>of</strong>auna taxa<br />

to metals was in part due to the various feeding strategies in that deposit feeders were most<br />

affected.<br />

Natural Aquatic Ecosystem Studies<br />

<strong>Lead</strong> stress in aquatic ecosystems has also been evaluated in natural communities.<br />

Studies examining community-scale endpoints, however, are complex, and interpretation can be<br />

confounded by the variability found in natural systems and the presence <strong>of</strong> multiple stressors.<br />

Natural systems frequently contain multiple metals, making it difficult to attribute observed<br />

adverse effects to single metals. For example, macroinvertebrate communities have been widely<br />

studied with respect to metals contamination and community composition and species richness<br />

(Winner et al., 1980; Chadwick et al., 1986; Clements, 1994). In these studies, multiple metals<br />

are evaluated and correlations between observed community level effects are ascertained. The<br />

results <strong>of</strong>ten indicate a correlation between the presence <strong>of</strong> one or more metals (or total metals)<br />

and the negative effects observed. While, correlation may imply a relationship between two<br />

AX7-203


variables, it does not imply causation <strong>of</strong> effects. The following studies suggest an association<br />

between Pb concentration and an alteration <strong>of</strong> community structure and function (see summary<br />

in Table AX7-2.6.2):<br />

Reduced Primary Productivity and Respiration<br />

Jayaraj et al. (1992) examined the effects <strong>of</strong> Pb on primary productivity and respiration in<br />

an algal community <strong>of</strong> two water bodies. Concentrations <strong>of</strong> Pb in water (6 to 80 mg/L) were<br />

found to significantly reduce primary productivity and increase respiration. The authors<br />

suggested that increased respiration indicated a greater tolerance to or adaptive mechanisms <strong>of</strong><br />

the resident heterotrophs to cope with lead stress.<br />

Alterations <strong>of</strong> Community Structure<br />

Deacon et al. (2001) studied a macroinvertebrate community in mine-affected waters <strong>of</strong><br />

Colorado. Initially, transplanted bryophytes were used to assess whether metals could<br />

bioaccumulate at various mine-affected and unaffected sites (Deacon et al., 2001; Mize and<br />

Deacon, 2002). <strong>Lead</strong> was bioaccumulated by the bryophytes, and median tissue concentrations<br />

at mine-affected sites (34 to 299 μg/g dw) were higher than at reference sites (2.5 to 14.7 μg/g<br />

dw). <strong>Lead</strong> concentrations in surface water and sediment ranged from


Tubificidae abundance. <strong>Lead</strong> was the only metal that was positively correlated to Nais species,<br />

while other metals were negatively correlated to Tubificidae (Rosso et al., 1994).<br />

The effects <strong>of</strong> metals and particle size on structuring epibenthic sea grass fauna (fish,<br />

mollusks, crustaceans, and polychaetes) was evaluated near a Pb smelter in South Australia<br />

(Ward and Young, 1982; Ward and Hutchings, 1996). Effluent from the smelter was the primary<br />

source <strong>of</strong> Pb and other metal contamination. Species richness and composition were evaluated<br />

near the Pb smelter along with metal concentrations in sediment. <strong>Lead</strong> levels in sediment (up to<br />

5270 mg/kg dw) correlated with negative effects on species richness and composition, while the<br />

other metals evaluated had similar correlations. There<strong>for</strong>e, Pb alone could not be identified as<br />

the sole metal causing stress.<br />

Tissue Bioaccumulation Associated with Alterations <strong>of</strong> Community Structure<br />

Several studies have examined the bioaccumulation <strong>of</strong> lead in aquatic systems with<br />

indices <strong>of</strong> community structure and function. A focused study on changes in Chironomidae<br />

community composition in relation to metal mines (New Brunswick, Canada) identified changes<br />

in Chironomidae richness (Swansburg et al., 2002). <strong>Lead</strong> was not detected (detection limit not<br />

given <strong>for</strong> any matrix) in the water column at any site. However, Pb levels in periphyton were<br />

significantly higher at mining sites (40.3 to 1387 mg/kg dw) compared to reference sites (not<br />

detected [ND], 33.3 mg/kg dw). Furthermore, Pb in chironomids was significantly higher at<br />

mine-affected sites (1.6 to 131 mg/kg dw) compared to reference sites (ND, 10.2 mg/kg dw).<br />

The concentrations in biota indicate that Pb is mobile and available to the aquatic community<br />

even though water concentrations were undetectable. Chironomidae richness was reduced at the<br />

sites receiving mining effluent containing Pb, Cd, Cu, and Zn.<br />

In another study, macroinvertebrate lead tissue concentrations (32.2 to 67.1 mg/kg dw at<br />

affected sites) collected from the Clark Fork River, Montana correlated negatively with total<br />

richness, EPT richness, and density (Poulton et al., 1995). Mean Pb levels were as high as<br />

67.1 mg/kg dw at sites most affected by lead. However, other metals, including Cd, Cu, and Zn,<br />

also were negatively correlated with total richness and EPT richness. There<strong>for</strong>e, attribution <strong>of</strong><br />

the observed effects to Pb is difficult, as other metals may be contributing factors.<br />

In Montana, the potential effects <strong>of</strong> metals on macroinvertebrate communities in the<br />

Boulder River watershed were evaluated (Rhea et al., 2004). Similar to the approach taken by<br />

AX7-205


Poulton et al. (1995), the effects on richness and abundance <strong>of</strong> EPT taxa were compared to metal<br />

concentrations in tissue (i.e., bi<strong>of</strong>ilm and macroinvertebrates). <strong>Lead</strong> levels in bi<strong>of</strong>ilm (32 to<br />

1540 mg/kg dw) were significantly correlated with habitat scores and macroinvertebrate indices<br />

(e.g., EPT taxa). However, macroinvertebrate tissue Pb levels were not significantly correlated<br />

with macroinvertebrate community level metrics. As with most natural systems with potential<br />

mine impacts, other metals also correlated with community level effects. However, the authors<br />

indicated that Pb concentrations in bi<strong>of</strong>ilm appeared to have the most significant impact on<br />

macroinvertebrate metrics.<br />

A detailed investigation <strong>of</strong> sediment, macroinvertebrates, and fish was conducted <strong>for</strong><br />

tributaries in the Aquashicola Creek watershed near a <strong>for</strong>mer zinc smelter in Palmerton, PA<br />

(Carline and Jobsis, 1993). The smelter deposited large amounts <strong>of</strong> Cd, Cu, Pb, and Zn on the<br />

surrounding landscape during its operation from 1898 to 1980. The goal <strong>of</strong> the study was to<br />

evaluate if there was a trend in the metal levels in sediment, macroinvertebrate and fish tissue,<br />

and community indices going away from the smelter. Sites were chosen, from 7.8 to 24.6 km<br />

from the smelter. There were no clear associations between proximity to the smelter and Pb<br />

levels in sediment, macroinvertebrate tissue, and fish tissue. Furthermore, there were no<br />

associations between proximity to the smelter and macroinvertebrate and fish diversity and<br />

richness. The authors suggested that the transport <strong>of</strong> metals in the watershed has decreased since<br />

the smelter ceased operation, and thereby no effects were observed.<br />

Ecosystems and Communities, Community Dynamics, and Trophic Structure<br />

As described in the SAB framework, community dynamics include interspecies<br />

interactions such as competition, predation, and succession (Young and Sanzone, 2002).<br />

Measures <strong>of</strong> biotic interactions (e.g., levels <strong>of</strong> seed dispersal, prevalence <strong>of</strong> disease in<br />

populations <strong>of</strong> focal species) provide important in<strong>for</strong>mation about community condition. If the<br />

community dynamics are disrupted, then the trophic structure may also be disrupted. According<br />

to the SAB framework, trophic structure refers to the distribution <strong>of</strong> species/taxa and functional<br />

groups across trophic levels. Measures <strong>of</strong> trophic structure include food web complexity and the<br />

presence/absence <strong>of</strong> top predators or dominant herbivores. There<strong>for</strong>e, this section discusses how<br />

aquatic species interactions can be affected by Pb. Examples <strong>of</strong> species interactions can include:<br />

AX7-206


• Predator-prey interactions (e.g., reduced avoidance <strong>of</strong> predators)<br />

• Prey consumption rate (e.g., increase or decrease in feeding)<br />

• Species competition (e.g., interference with another species, increased aggressive<br />

behavior)<br />

• Species tolerance/sensitivity (e.g., the emergence <strong>of</strong> a dominant species due to<br />

contaminant tolerance or sensitivity)<br />

Species interactions are highly relevant to a discussion about the effects <strong>of</strong> Pb on natural<br />

aquatic ecosystems, because effects on species interactions could potentially affect ecosystem<br />

function and diversity. Some examples <strong>of</strong> Pb induced changes in species interactions are<br />

presented below (see summary in Table AX7-2.5.2).<br />

Predator-prey Interactions<br />

Lefcort et al. (1999) examined the competitive and predator avoidance behaviors <strong>of</strong> snails<br />

and tadpoles in outdoor mini-ecosystems with sediment from a metals-contaminated Superfund<br />

site (i.e., Pb, Zn, Cd). Previous investigations <strong>of</strong> aquatic invertebrates and vertebrates yielded Pb<br />

tissue concentrations <strong>of</strong> 9 to 3800 mg/kg dw and 0.3 to 55 mg/kg dw, respectively. Several<br />

species interactions were studied in the presence <strong>of</strong> metal-contaminated sediment:<br />

Snails and tadpoles have similar dietary behaviors. Thus, when placed in the same habitat<br />

they will compete <strong>for</strong> the same food items and negatively affect one another. However, when<br />

tadpoles exposed to a predator (i.e., through biweekly additions <strong>of</strong> 20 mL <strong>of</strong> water from tanks<br />

housing sunfish—10 mL from sunfish-fed snails, 10 mL from sunfish-fed tadpoles) were placed<br />

with snails, the tadpoles reduced sediment ingestion, while snails increased ingestion. Thus,<br />

snails were exposed to greater quantities <strong>of</strong> metals in sediment.<br />

In an uncontaminated environment, snail recruitment (i.e., reproduction) was reduced in<br />

the presence <strong>of</strong> tadpoles. The addition <strong>of</strong> tadpoles increased the competition <strong>for</strong> food in the <strong>for</strong>m<br />

<strong>of</strong> floating algae and the snails switched to feeding on algae that grew on the sediment. This<br />

decrease was due to competition alone. The effects on snail recruitment were even higher when<br />

tadpoles, the influence <strong>of</strong> a predator (i.e., sunfish extract), and metals in the sediment were all<br />

present. However, the predator effect was indirect in that the tadpoles hid in the algal mats<br />

<strong>for</strong>cing the snails to feed primarily on the benthic algae that grew on the sediment with high<br />

AX7-207


metal levels. Furthermore, although not significant, Pb levels in snails were higher when<br />

tadpoles and sunfish extract were present than when only metals in the sediment were present.<br />

Finally, snail predator avoidance was assessed. Snails (control and lead-exposed) were<br />

stimulated with a predator indicator (i.e., crushed snails and an extract <strong>of</strong> crushed snail). Control<br />

snails changed behaviors in the presence <strong>of</strong> the predator indicator, while exposed snails did not<br />

alter their behavior. The authors suggested that metal exposure caused behavioral changes that<br />

alter competitive interactions and the perception <strong>of</strong> predators by the snails. Thus, Pb may affect<br />

the predator avoidance response <strong>of</strong> snails.<br />

In further study, Lefcort et al. (2000) examined the predator avoidance behaviors <strong>of</strong> snails<br />

and caddisflies. In separate experiments, the avoidance behavior <strong>of</strong> the snail, Physella<br />

columbiana, and four caddisfly genera (Agrypnia, Hydropsyche, Arctopsyche, Neothremma)<br />

were evaluated. The snails were collected from reference lakes and lakes downstream <strong>of</strong> the<br />

Bunker Hill Superfund site. The snails from the affected lakes generally had higher cadmium,<br />

Pb, and zinc tissue levels implying previous exposure to these metals. Snail predator avoidance<br />

behavior was tested by exposure to crushed snail extract. Snails from the affected lakes did not<br />

reduce their activity when exposed to the snail extract, implying a reduced predator avoidance.<br />

The lack <strong>of</strong> response may make the snails at the affected lakes more prone to predation.<br />

The caddisflies were evaluated at 36 sites from six different streams. As with the snails,<br />

the caddisflies from the affected streams had higher cadmium, Pb and zinc tissue levels. The<br />

time <strong>for</strong> caddisfly larvae to respond (i.e., how long immobile) to disturbance (i.e., lifted from<br />

water <strong>for</strong> 3 seconds and moved to a new location) was evaluated. There was no correlation<br />

between tissue metal level and any response variable (Lefcort et al., 2000). There<strong>for</strong>e, the<br />

authors concluded that preexposure to metals did not reduce predator avoidance <strong>for</strong> caddisflies.<br />

Weber (1996) examined juvenile fathead minnows exposed to 0, 0.5, or 1.0 ppm Pb in<br />

water during a 2-week preexposure and 2-week testing period (4 weeks total exposure). Feeding<br />

behavior was evaluated by presenting two prey sizes (2-day-old and 7-day-old Daphnia magna).<br />

Control fish began switching from larger, more difficult-to-capture 7-day-old daphnids to<br />

smaller, easier-to-catch 2-day-old prey by day 3. <strong>Lead</strong>-exposed fish displayed significant<br />

switching at day 3 (at 0.5 ppm) or day 10 (at 1.0 ppm). Thus, exposure to Pb delayed the altering<br />

<strong>of</strong> prey size choices to less energetically costly prey.<br />

AX7-208


Lefcort et al. (1998) exposed spotted frogs (Rana luteiventris) to 0.05 to 50 ppm Pb in<br />

water <strong>for</strong> 3 weeks. High levels <strong>of</strong> Pb reduced the fright response <strong>of</strong> tadpoles; suggesting a<br />

reduced avoidance <strong>of</strong> predators.<br />

Bullfrog larvae exposed to Pb in water (0.78 mg/L) and high or low dissolved oxygen<br />

were monitored <strong>for</strong> respiratory surfacing behavior (Rice et al., 1999). Larvae had a significantly<br />

increased number <strong>of</strong> trips to the water surface regardless <strong>of</strong> oxygen content. Thus, the authors<br />

suggest that Pb may affect oxygen uptake such that larvae are under greater predation pressure<br />

due to increased time spent at the surface.<br />

Weis and Weis (1998) evaluated the effect <strong>of</strong> Pb exposure on mummichog (Fundulus<br />

heteroclitus) larvae prey capture rate, swimming behavior, and predator avoidance. Prey capture<br />

rates were affected after 4 weeks exposure at 1.0 mg Pb/L. The larvae were also more<br />

vulnerable to predation by grass shrimp (Palaemonetes pugio) at 1.0 mg Pb/L. Finally, the<br />

swimming behavior <strong>of</strong> mummichog larvae was affected at 0.3 and 1.0 mg Pb/L. Once the larvae<br />

were no longer exposed to Pb, they recovered their ability to capture prey and avoid predators.<br />

Clearly, exposure to Pb does affect the predator-prey interactions and the ability <strong>of</strong> prey to<br />

avoid predators. The effect <strong>of</strong> Pb on these ecological functions may alter community dynamics.<br />

AX7.2.5.3 Summary<br />

The effects <strong>of</strong> Pb have primarily been studied in instances <strong>of</strong> point source pollution rather<br />

than area-wide atmospheric deposition; thus, the effects <strong>of</strong> atmospheric Pb on ecological<br />

condition remains to be defined. The evaluation <strong>of</strong> point source Pb within the <strong>EPA</strong> Ecological<br />

Condition Framework has been examined primarily in relation to biotic conditions. The<br />

available literature focuses on studies describing the effects <strong>of</strong> Pb in natural aquatic ecosystems<br />

with regard to community composition and species interactions. The effects <strong>of</strong> Pb on the biotic<br />

condition <strong>of</strong> natural aquatic systems can be summarized as follows: there is a paucity <strong>of</strong> data in<br />

the general literature that explores the effects <strong>of</strong> Pb in conjunction with all or several <strong>of</strong> the<br />

various components <strong>of</strong> ecological condition as defined by the <strong>EPA</strong>. However, numerous studies<br />

are available associating the presence <strong>of</strong> Pb with effects on biotic conditions.<br />

In simulated microcosms or natural systems, environmental exposure to Pb in water and<br />

sediment has been shown to affect energy flow and nutrient cycling and benthic community<br />

structure. In field studies, Pb contamination has been shown to significantly alter the aquatic<br />

AX7-209


environment through bioaccumulation and alterations <strong>of</strong> community structure and function.<br />

Exposure to Pb in laboratory studies and simulated ecosystems may alter species competitive<br />

behaviors, predator-prey interactions, and contaminant avoidance behaviors. Alteration <strong>of</strong> these<br />

interactions may have negative effects on species abundance and community structure. In<br />

natural aquatic ecosystems, Pb is <strong>of</strong>ten found coexisting with other metals and other stressors.<br />

Thus, understanding the effects <strong>of</strong> Pb in natural systems is challenging given that observed<br />

effects may be due to cumulative toxicity from multiple stressors.<br />

AX7-210


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