Carcinogenesis in mice after injection of soluble plutonium citrate

The carcinogenicity of injected soluble plutonium ((239)Pu) citrate was investigated in life-span animal experiments using mice of three strains, C3H, C57BL/6 and their hybrid BC3F(1), that have different spectra of spontaneous and radiation-induced tumors. Bone tumors, mostly osteosarcomas, were induced at skeletal doses of 0.6 to 0.7 Gy, and the incidence increased markedly at doses of 2 to 4 Gy in all strains, while lymphoid tumors appeared to decrease at higher doses; the incidences of bone tumors remained higher at higher doses, suggesting a differential and competitive dose response between bone and lymphoid tumors. Among the histological phenotypes of lymphoid tumors, nonthymic, pre-B-cell type leukemic lymphomas were induced preferentially and early, while thymic lymphomas and myeloid leukemias were rarely or never observed in any of the strains after injection of (239)Pu. These findings indicate a specificity of (239)Pu-induced carcinogenesis in mice that is different from that of external low-LET irradiations.