MATERNAL AND DEVELOPMENTAL TOXICITY OF MANGANESE IN THE MOUSE

Manganese (N) chloride tetrahydrate was investigated in Swiss mice for maternal and developmental toxicity after subcutaneous (s.c.) exposur e to doses of 0, 2, 4, 8 and 16 mg/kg per day from gestation day 6 thr ough 15. Females were sacrificed on gestation day 18, and fetuses were examined for external, visceral, and skeletal abnormalities. Maternal toxicity included significant reductions in weight gain and food cons umption at 8 and 16 mg/kg/day, as well as several treatment-related de aths in the high dose-group. There were no treatment-related effects o n the number of total implants, early resorptions, dead fetuses or sex ratio, whereas a significant increase in the number of late resorptio ns was found in the 4, 8, and 16 mg/kg/day groups. Fetotoxicity, consi sting primarily of reduced fetal body weight and an increased incidenc e of morphological defects was also observed at 8 and 16 mg/kg/day. Th ere were no differences between control and manganese-treated groups i n the incidence of individual or total malformations. The no observabl e adverse effect level (NOAEL) for maternal toxicity of MnCl2.4H(2)0 i n mice was 4 mg/kg/day, while the NOAEL for embryo/fetal toxicity was 2 mg/kg/day.