Normal Mercury Level in Human Embryos and Fetuses

Abstract

The normal level of total mercury in human embryos and fetal organs (liver, kidney and cerebrum) was first indicated and it was shown that this metal is their constant component in the amount with an appreciable individual variability. As for the stage difference of the contents of the fetal organs, a significant decrease in the third-trimester liver compared to the second-trimester-liver was noted. The contents of the third-trimester liver and kidney were lower than the respective adult values. However, no significant difference of the levels was shown in the cerebrum throughout the period from fetal to adult stage, and this does not support the prevailing presumption that human fetal brain concentrates mercury. Little correlation between the mercury level in the maternal pubic hair and its level in the embryo was indicated.

The magnitude of methylmercury-induced cytotoxicity and cell cycle arrest is p53-dependent

“…In contrast, rat in vivo tissues required approximately two-fold higher doses than in vitro studies and in vivo mouse studies before cell cycling impacts were observed. For perspective, a human LOAEL is estimated at 0.5-1.0 g/gm based on data collected from neonates involved in the Minimata poisoning (Choi et al, 1978), a nonsymptomatic Japanese population (Nishimura et al, 1974) and from the study of Lapham et al (1995) in the Seychelles Islands. A summary of the literature indicates that humans may be more sensitive to the neurodevelopmental effects of MeHg than mice, which in turn, are less sensitive than rats.…”