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

AX6-173
Table AX6-6.1 (cont’d). Placental Transfer of Lead from Mother to Fetus
Reference and
Study Location Study Description Pb Measurement Findings, Interpretation
Other Locations
Clark (1977)
Zambia
Casey and Robinson
(1978)
New Zealand
122 mother-infant pairs residing near the
Broken Hill Pb Mine and Smelter. Control
group of 31 mother-infant pairs.
40 fetuses (23 stillborn and 17 died within
24 hrs), 22 to 43 wks gestation.
Chaube et al. (1972) 50 embryos and fetuses 31 to 261 days
gestational age that were aborted.
Mine group:
Maternal blood Pb:
Mean 41.2 µg/dL (SD 14.4)
Infant cord blood Pb:
Mean 37.0 µg/dL (SD 15.3)
Control group:
Maternal blood Pb:
Mean 14.7 µg/dL (SD 7.5)
Infant cord blood Pb:
Mean 11.8 µg/dL (SD 5.6)
Pb detected in 73% of liver, 23% of kidneys, 40%
of brain, 25% of heart, 33% skeletal muscle, and
70% of bone samples. Pb also detected in 11 of 14
lung samples (79%).
Overall Pb concentration in soft tissue:
0.1-2.4 µg/g dry matter
Pb concentration in bone samples:
0.4-4.3 µg/g dry matter
Among the 1st trimester specimens:
Pb detected in 77% of liver, 15% of brain, and 30%
of kidney samples.
Mine group:
Correlation coefficient = 0.77
Control group:
Correlation coefficient = 0.56
Pb concentrations in bone were higher than in
the other tissues.
Levels in brain, heart, and muscle similar to
values reported for children and adults. Levels
in liver, kidney, lung, and bone were much less
than adult values, suggesting much of the Pb that
enters the body after birth accumulates in these
tissues.
Placental transfer occurs as early as the 1st
trimester of pregnancy.