Differential Induction of Bone and Hematopoietic Tumors in C3H Mice after the Injection of ²³⁹Pu Citrate

Abstract

Although alpha-emitting plutonium is easily distributed in the skeleton via circulation and subsequenlty induces bone tumors, there is little evidence that hematopoietic neoplasias are highly induced even though bone marrow stem cells are irradiated internally by alpha particles. We injected groups of female C3H strain mice with doses of ²³⁹Pu citrate from 500 to 10000 Bq to investigate the dose-related spectrum of tumor types induced during a lifetime. Survival time was reduced strikingly in all the injected mice due to much earlier induction of bone and lymphoid tumors as compared to the control animals that showed a variety of soft tissue tumors after a longer period of survival. Induction of osterosarcomas was dose-dependent, being maximal in 70% of the animals 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 lymphocytic 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, rather thymic lymphomas or histiocytic lymphomas were found very late in 20% and other soft tissue tumors, including lung, liver and ovary tumors, were noted in 60%. Neither myeloid leukemia nor other myelogenous neoplasias were found in the control and ²³⁹Pu-injected animals that received a mean skeletal dose of 3 Gy or more. These results indicate that the differential induction of bone tumors and hematopoietic tumors in mice depends on the dose range and the time after the injection of plutonium.