Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX6-65
Table AX6-3.8 (cont’d). Occupational Exposure to Organolead and Inorganic Lead in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
United States (cont’d)
Stewart et al. (2002)
U.S.
Tassler et al. (2001)
U.S.
Bolla et al. (1995)
U.S.
Mitchell et al. (1996)
U.S.
Population as described in Stewart et al.
(1999) and Schwartz et al. (2000b). Data
on 20 neurobehavioral tests from 529
former organolead workers were
evaluated to determine if the previously
described relationship with bone Pb
levels is influenced by the apolipoprotein
E (ApoE) genotype.
490 former organolead workers, mean
age 58 (7.5) yrs. The peripheral nervous
system was examined with sensory
pressure thresholds, and pinch and grip
strength.
190 current workers in organolead
manufacturing (from the 222 described in
Schwartz et al., 1993) mean age 45 (8)
yrs compared to 52 referents, mean age
45 (8) yrs and 144 solvent exposed
workers, mean age 42 (8) yrs.
58 organolead workers, self-selected for
a clinical evaluation. Mean age 45 (7.1)
yrs.
Mean (SD) blood Pb 5
(2.6) µg/dL
Mean (SD) DMSA-chelatable Pb
19 (16.3) µg
Mean (SD) current tibia Pb
15 (9.4) µg/g
Mean (SD) peak tibia Pb 24
(17.6) µg/g
IH found organic Pb was 65 to
70% of exposure in production
area.
Mean (SD) weighted avg blood
Pb 24 (9.4) µg/dL
Mean (SD) blood Pb 19
(6.5) µg/dL
Mean (SD) lifetime blood Pb 26
(9.1) µg/dL
Mean (SD) lifetime urine Pb 51
(18.8) µg/L
In 20 linear regression models, coefficients for the ApoE and tibia Pb
interaction term were negative in 19 with significance reached for digit
symbol (∃ = !0.109 [SE 0.054], p # 0.05), Purdue pegboard dominant
(∃ = 0.068 [SE 0.028], p # 0.05) and complex reaction time (∃ = !0.003
[SE 0.001], p#0.05) and borderline significance existed for symbol digit
(∃ = !0.046 [SE 0.026], p # 0.10), Trails A (∃ = !0.303, [SE 0.164]
p # 0.10) and Stroop (∃ = !0.013 [SE 0.008], p # 0.10). The slope of the
relation between tibia Pb and neurobehavioral outcome was more
negative in those individuals with at least one ε4 allele than individuals
without this allele. It is suggested that the presence of one Apo-ε-4 allele
increases the risk of persistent central nervous system effects of Pb.
No strong association was found between Pb biomarkers and measures
of sensory and motor function after adjusting for age. The authors
attributed the findings to decreased sensitivity of the peripheral nerves in
this dose range of inorganic Pb or the possibility of differential repair in
the peripheral nervous system compared to the central nervous system.
Pb and solvent exposure associated with adverse effects on tests of
manual dexterity. When compared to the solvent group Pb exposure had
greater impairment on memory and learning and less on executive/motor
tests. An elevated neuropsychiatric score was present in 43% of the Pb
group, 15% of the solvent and 7% of the referent group.
The most common symptoms were memory loss 74%, joint pain 56%,
trouble sleeping 54%, irritability 51%, paresthesia 49%, fatigue 49%,
nightmares 35%, moodiness 28%, headaches 21% and depression 21%.
Of the 31 workers receiving nerve conduction studies, 29% were normal,
carpal tunnel syndrome 36%, cubital tunnel syndrome 3%, median
neuropathy 3%, ulnar neuropathy 23%, mononeuropathy in lower
extremity 5%, tarsal tunnel syndrome 7% and sensorimotor
polyneuropathy 36%. 39 workers had neurobehavioral evaluation with
64% had abnormal tests of which 46% were considered to be consistent
with a toxic exposure.