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GESTATIONAL MERCURY VAPOR EXPOSURE AND DIET CONTRIBUTE TO MERCURY ACCUMULATION IN NEONATAL RATS.
Citation:
MORGAN, D. L., H. C. PRICE, R. FERNANDO, S. M. CHANDA, R. W. O'CONNOR, STANLEY BARONE, D. W. HERR, AND R. BELILES. GESTATIONAL MERCURY VAPOR EXPOSURE AND DIET CONTRIBUTE TO MERCURY ACCUMULATION IN NEONATAL RATS. ENVIRONMENTAL HEALTH PERSPECTIVES. National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, 114(5):735-739, (2006).
Impact/Purpose:
To better understand how mercury in neonatal tissues may adversely affect growth and development
Description:
Exposure of pregnant Long-Evans rats to elemental mercury (Hg0) vapor resulted in a significant
accumulation of Hg in tissues of neonates. Because elevated Hg in neonatal tissues may adversely
affect growth and development, we were interested in how rapidly Hg was eliminated from
neonatal tissues. Pregnant rats were exposed to 1, 2, or 4 mg Hg0 vapor/m3 or air (controls) for 2
hr/day from gestation day 6 (GD6) through GD15. Neonatal brain, liver, and kidney were analyzed
for total Hg at various times between birth and postnatal day 90 (PND90). Milk was analyzed for Hg
between birth and weaning (PND21). Before weaning, the Hg levels in neonatal
tissues were proportional to maternal exposure concentrations and were highest in kidney
followed by liver and then brain. There was no elimination of Hg between birth and weaning,
indicating that neonates were exposed continuously to elevated levels of Hg during postpartum
growth and development. Consumption of milk from exposed dams resulted in a slight increase in
kidney Hg concentration during this period. Unexpectedly, neonatal Hg accumulation increased
rapidly after weaning. Increased Hg was measured in both control and exposed neonates and was
attributed to consumption of NIH-07 diet containing trace levels of Hg. By PND90, tissue Hg
levels equilibrated at concentrations similar to those in unexposed adult Long-Evans rats fed the
same diet. These data indicate that dietary exposure to trace amounts of Hg can result in a
significantly greater accumulation of Hg in neonates than gestational exposure to high
concentrations of Hg0 vapor.