Long-term effects on tumour incidence and survival from 241Am exposure of the BALB/c mouse in utero and during adulthood.

BALB/c mice were given 100, 500 or 1500 Bq/g 241Am at day 14 of pregnancy. The offspring were separated from the mothers at birth and followed until death. In addition, adult females and one group of males were also studied for the effects of 241Am following treatment with 45-213 Bq/g. Adults treated with 241Am showed significantly shortened survival and increased incidence of osteosarcoma (to 40 - 50%). The data also suggest that the female mouse is more susceptible to induction of osteosarcoma than the male. There was also a significant increase in osteosarcoma, all bone tumours, all sarcomas, and all leukaemias in the offspring from the contaminated mothers, although this appeared to occur independently of dose. Calculations of the number of osteosarcomas induced per Gy varied for contamination of adult mice between 0.2 and 0.01 and for the offspring between 6 and 0.6. Thus, offspring seemed to be about 10 times more at risk if osteosarcomas induced per mouse Gy are compared. Surprisingly, offspring from mothers treated with 241Am displayed a longer survival time than controls, possibly due to fewer deterministic lung diseases appearing early in life.