Am-241 Distribution And Retention In Pregnant Mice, In Their Offspring And In Nonpregnant Mice - Comparison Between Continuous Am Administration And Single Injection

Pregnant BALB/c mice and age and sex matched nulliparous controls were contaminated with Am-241 (13 kBq per mouse) by two different procedures: (1) a single intraperitoneal injection at the 14th day of gestation, and (2) continuous administration between the 7th and 14th day of gestation and between the 14th and 19th day of gestation. Continuous administration was achieved by implanting osmotic pumps filled with Am-241 which released the Am-241 activity at a constant rate. Five days after the termination of contamination, Am-241 incorporation was measured in the tissues of adults and in the liver and the femur of newborn and one-month-old mice. Pregnancy results in higher Am-241 concentrations in bone but lower concentrations ir the liver of the mothers. Protracted administration of Am-241 compared to a single injection resulted in a lower concentration of Am-241 in the livers of pregnant mice, their nulliparous controls and from newborn mice. The higher Am-241 concentration in the femur at birth after protracted exposure before 14 days of gestation compared to protracted exposure after 14 days of gestation could reflect the increased placental transfer of Am-241 with advancing gestational age. Radiation doses to the femur were estimated between 4 and 20 mGy. Haemopoietic changes were noticed at these dose levels in all groups until at least 6 months after birth.