Evaluation of the perinatal and postnatal effects of uranium in mice upon oral administration.

Perinatal and postnatal studies were performed in Swiss mice given uranium--as uranyl acetate dihydrate--at daily dosages of 0, 0.05, 0.5, 5, and 50 mg/kg from day 13 of pregnancy until weaning of the litters on day 21 post-birth. Postnatal development was monitored after 0, 4, and 21 d of lactation. At doses of 0, 0.05, 0.5, and 5 mg/kg.d, treatment with uranium had no significant effect on sex ratios, mean litter size, pup body weight, or pup body length throughout lactation. Significant decreases in the mean litter size on postnatal day 21, and in the viability and lactation indices were observed at the 50 mg/kg.d dose level. When comparing the "no observable effect level" (NOEL) for reproductive effects of uranium, with the concentrations of the metal usually ingested by men, a safety factor below 1,000 can be estimated.