Metabolism of Zinc-65 in the Rat Consideration of Permissible Exposure Limits

Abstract

Data are presented on the absorption of Zn65 under various conditions, on its distribution and retention following a single administration, and on its buildup in tissues during chronic feeding. Highest concentrations of Zn65 were observed in hair, bone and prostate, the three tissues which did not attain steady-state levels of Zn65 during extended periods of Zn65 feeding. Accumulation in the total body appears to be the critical consideration, however, due to the greater absorption of the decay energy in the larger organism and the lower permissible dose rate recommended for total body irradiation. Special consideration may need be given to the very young, in view of the ready transfer of Zn65 across the placenta and the enhanced intestinal absorption during the first few weeks of life.