revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 138
2. HEALTH EFFECTS
The highest NOAEL values and all reliable LOAEL values for neurotoxic effects in each species and
duration category are listed in Table 2-3 and plotted in Figure 2-3 for organic mercury.
2.2.2.5 Reproductive Effects
Inorganic Mercury. In an attempt to terminate her pregnancy, a 31-year-old woman ingested 30 mg Hg/kg
as mercuric chloride in week 10 of her pregnancy (Afonso and deAlvarez 1960). Despite gastric lavage and
treatment with dicapmerol, 13 days after exposure vaginal bleeding and uterine cramps occurred, followed
by spontaneous abortion of the fetus and placenta. It was inconclusive whether the abortion was directly
due to the mercury exposure.
Organic Mercury. No studies were located regarding reproductive effects in humans following oral
exposure to organic mercury.
Abortions and decreased mean litter size are the predominant reproductive effects in different species of
animals following oral exposure to organic mercury. Groups of 30 pregnant Fischer 344 rats were orally
administered 10, 20, or 30 mg/kg as methylmercuric chloride dissolved in saline on Gd 7. Controls were
given saline only (n=30). Maternal body weight gain and deaths were monitored. On Gd 20, the dams
were laparotomized under ether anesthesia, and the fetuses were removed. Surviving fetuses were
examined for gross toxic effects, sex, and weight; half were stained for skeletal examination. Mercury
levels in maternal and fetal organs were measured. The LD50 of methylmercuric chloride for fetuses was
calculated. Maternal body weights were decreased for 2 days in rats given 10 mg/kg, for 6 days in rats
given 20 mg/kg, and were continuously decreased for rats given 30 mg/kg methylmercuric chloride.
Survival rates of fetuses were 19.2, 41.4, and 91.1% less than controls for the 10, 20, and 30 mg/kg methylmercuric
chloride groups, respectively. Implantation sites in the 3 groups decreased by 5.9, 13.7, and
22.5%, respectively, compared with controls. Preimplantation losses in the 3 groups were 17.2, 24.8, and
30.1%, respectively; postimplantation losses were 16.7, 34.1, and 88.9%, respectively. The reduction of
litter weight was greatly enhanced with increasing methylmercuric chloride doses (32.3, 67.0, and 89.2%,
respectively), presumably due to postimplantation loss, which already increased at high treatment levels.
The LD50 of methylmercuric chloride for fetuses was determined to be 16.5 mg/kg. Mercury content in
maternal organs was highest in the kidneys, followed by blood, spleen, liver, and brain, while in fetal
organs it was highest in the liver (Lee and Han 1995).