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

MERCURY 152
2. HEALTH EFFECTS
Harderian, exorbital lachrymal, and parotid salivary glands (Khera and Tabacova 1973). No effects
occurred at the lower dose of 0.05 mg Hg/kg/day. Fetal liver injury at the ultrastructural level (e.g.,
decreased mitochondrial volume density, enzyme activity, and protein synthesis in fetal hepatocytes) was
reported after chronic exposure to low doses of 0.7–1.4 mg Hg/kg/day as methylmercury in the drinking
water of rats for 1 month before mating and up to the end of pregnancy (Fowler and Woods 1977). The
developing immune system was affected in newborn Sprague-Dawley rats exposed to 0.5 mg Hg/kg/day as
methylmercury through the placenta and/or milk (Ilback et al. 1991). Results showed that exposure caused
increased thymus lymphocyte activity in offspring exposed during gestation and lactation, while decreased
spleen lymphocyte activities were observed in offspring exposed during lactation only. Cell-mediated
cytotoxicity was decreased by 41% (p