DIFFERENTIAL INDUCTION OF BONE AND HEMATOPOIETIC TUMORS IN C3H MICE AFTER THE INJECTION OF PU-239 CITRATE

Although alpha-emitting plutonium is easily distributed in the skeleto n via circulation and subsequenlty induces bone tumors, there is littl e evidence that hematopoietic neoplasias are highly induced even thoug h bone marrow stem cells are irradiated internally by alpha particles. We injected groups of female C3H strain mice with doses of Pu-239 cit rate from 500 to 10000 Bq to investigate the dose-related spectrum of tumor types induced during a lifetime. Survival time was reduced strik ingly in all the injected mice due to much earlier induction of bone a nd lymphoid tumors as compared to the control animals that showed a va riety of soft tissue tumors after a longer period of survival. Inducti on of osterosarcomas was dose-dependent, being maximal in 70% of the a nimals that received a mean skeletal dose of 10 Gy or less, but was 48 % or less at 20 Gy or more. Non-thymic lymphomas accompanied by lympho cytic leukemia were observed in only 4-6% of the animals that received a dose of 10 Gy or less whereas it was maximal in 17-19% at 20 Gy or more. In contrast, there were no bone tumors in the control animals, r ather thymic lymphomas or histiocytic lymphomas were found very late i n 20% and other soft tissue tumors, including lung, liver and ovary tu mors, were noted in 60%. Neither myeloid leukemia nor other myelogenou s neoplasias were found in the control and Pu-239-injected animals tha t received a mean skeletal dose of 3 Gy or more. These results indicat e that the differential induction of bone tumors and hematopoietic tum ors in mice depends on the dose range and the time after the injection of plutonium.