Developmental toxicity of cobalt in the rat.

To determine the potential developmental toxicity of cobalt, pregnant Sprague-Dawley rats were given by gavage a daily dose of 0, 25, 50; and 100 mg/kg cobalt(II) chloride on d 6-15 of gestation. Females were sacrificed on d 20. Maternal effects included significant reductions in weight gain and food consumption, particularly at 100 mk/kg.d. Hematocrit, hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin, and reticulocytes were increased significantly in the 100-mg/kg.d group. No treatment-related changes were recorded in the number of corpora lutea, total implants, resorptions, the number of live and dead fetuses, fetal size parameters, or fetal sex distribution data. Increased incidence of stunted fetuses per litter was the only adverse finding at 50 and 100 mg/kg.d group. However, this increase was not statistically significant. Examination of fetuses for gross external abnormalities, skeletal malformations, or ossification variations revealed that cobalt did not produce teratogenicity or significant fetotoxicity in the rat at doses as high as 100 mg/kg.d.