Characteristics of the transfer of mercury and other trace elements between dam and fetus in a relatively high‑mercury content species, the small Indian mongoose (Urva auropunctata)

Abstract

We provide the first data regarding the maternal-to-fetal transfer of toxic trace elements (total Hg (THg) and organic Hg (OHg), As, Cd, and Pb) and seven essential minerals (Mg, Cr, Mn, Fe, Cu, Zn, and Se) in the tissues of 29 pairs of small Indian mongoose that were naturally exposed to metals. The fetal mass negatively correlated with the fetal liver O/THg ratio, suggesting that mineralization of Hg from the organic form might occur during fetal growth. The maternal THg and OHg concentrations and THg/Se molar ratios in whole blood and the fetal whole blood (FB)/maternal whole blood (MB) ratios of the OHg and THg concentrations significantly correlated with the fetal hepatic and cerebral Hg levels, indicating that the maternal blood THg and OHg concentrations and the THg/Se and FB/MB ratios may be useful biomarkers of the Hg contents of fetal organs. It was noted that the fetal THg and OHg levels in the liver and whole blood tended to be lower when the dams were exposed to high levels of Hg, suggesting that the placental barrier mechanism may be activated when mongooses are exposed to high levels of Hg. Analysis of the differences in trace element concentrations between maternal blood containing high (>0.044 ppm) and low (<0.044 ppm) Hg exposure showed that fetuses with high maternal Hg exposure may be at higher risk of Pb exposure and Zn depletion than those with dams exposed to low levels of Hg.