Distribution of 241Am in offspring from BALB/c mice injected with 241Am at 14 days of gestation: relation to calcium and iron metabolism and comparison with distribution of 241Am after injection of adults.

Pregnant mice were given intravenous injections of 241Am citrate at 14 days of gestation. The fetal skeleton had a higher or similar uptake of 241Am per gram of fresh tissue than the liver. In comparison, the liver in adults concentrated 5 to 20 times more 241Am per gram of fresh tissue than the bones. Measurement of changes in calcium and iron content and concentration with time, showed that in the developing mice intensive calcification of bones determined the uptake of 241Am. The 241Am uptake was related to the calcium concentration of the fetal bones, which was greater at 14 days of gestation in the anterior bones, the mandibles and calvaria, than in the ribs and femurs. Transfer of 241Am to pups via milk resulted in further accumulation of 241Am in the skeleton and liver. The incorporation in the skeleton persisted after weaning and contributed to the lifetime body burden. The 241Am concentration decreased rapidly with time after injection in relation to the growth of the organs. Radiation dose rates and cumulative radiation doses were calculated for liver and bones of contaminated offspring.