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

AX5-125
Table AX5-8.1 (cont’d). Bone Growth in Lead-exposed Animals
Compound
Dose/Concentration
Duration Exposure
Route Species Effects Blood Level Reference
Pb acetate
0.15% or 0.45%
GD 4 until Day 55
In drinking water
Pb acetate
1000 ppm
22–26 days
In drinking water
Abbreviations
Mg—milligram
µg—microgram
ppm—parts per million
GD—gestational day
Pb—lead
g—gram
µg%—microgram percent
Rat A dose-dependent decrease in load to failure in tibia from Pb-exposed
(0.15% and 0.45% Pb acetate in drinking water) male pups only.
Hormone treatments (L-dopa, testosterone or dihydrotestosterone in
males, or estradiol in females) failed to attenuate Pb deficits during the
pubertal period. Distraction osteogenesis experiments performed after
stabilization of endocrine parameters (at 100 days of age) found
decreased new endosteal bone formation and gap x-ray density in the
distraction gaps of Pb-exposed animals.
Rat Pb disrupted mineralization during growth in demineralized bone
matrix implanted subcutaneously into male rats. In the matrix that
contained 200 micrograms Pb/g of plaque tissue, alkaline phosphatase
activity and cartilage mineralization were absent, though calcium
deposition was enhanced. Separate experiments found enhanced
calcification and decreased alkaline phosphatase activity in rats
implanted with a control (no Pb) matrix and given 1000 ppm Pb in
drinking water for 26 days.
l—liter
m 3 - —cubic meter
Exp—experimental group
wk—week
dL—deciliter
%—percent
Offspring:
0.15% Pb = 67–192 µg/dL;
0.45% Pb = 120–388 µg/dL
Blood Pb (µg/dL)
Control:
Implantation Day 0 = 1.3 ± 0.6;
Day 8 = 2.2 ± 0.9; Day 12 = 2.1 ±
0.7.
Pb added to matrix:
Implantation Day 0 = 1.5 ± 0.8;
Day 8 = 5.7 ± 0.8 a,b ; Day 12 = 9.5
± 0.5 a,b .
Pb in drinking water:
Implantation Day 0 = 129.8 ±
6.7 a ; Day 8 = 100.6 ± 6.8 a,b
Day 12 = 96.4 ± 5.3 a,b .
a
Significant (p # 0.05) difference
from control.
b
Significance (p # 0.05)
difference from corresponding
value at implantation (Day 0).
Ronis et al. (2001)
Hamilton and
O’Flaherty (1995)