Abstract
Female C3H strain mice, which do not spontaneously exhibit frequent bone tumors and myeloid leukemias, were injected intraperitoneally with various doses of 10 to 12000 Bq/animal of monomeric 239Pu citrate to clarify lifetime carcinogenesis caused by alpha-particles distributed mainly in the skeleton. Survival time was reduced significantly at mean skeletal doses of more than 2.93 Gy and was accompanied by marked life-shortening as compared to the controls due to an earlier increase in neoplastic or non-neoplastic death. Bone tumors, almost all of which were osteosarcomas, were not found in the controls, whereas their incidence increased sharply to a maximum of 96% at 6.92 Gy, then dropped at higher doses (20% at 42.4 Gy). Although lymphoid tumors were present in 20% of the control animals, their incidence dropped to zero at 6.92 Gy, then increased at higher doses (36% at 25.5 Gy). Non-thymic, mostly pre-B cell type, leukemic lymphomas mainly occurred at early time after 239Pu-injection; whereas, in the controls thymic, lymphocytic or histiocytic lymphomas occurred only at a later time. Of the other soft tissue tumors, neither myeloid leukemias nor myelogenous neoplasms were found in the controls or the 239Pu-injected animals. Tumors affecting the lungs, liver, ovaries, and skin were much fewer or not found at mean doses of more than 2.93 Gy. These results indicate dose-dependent, differential tumor induction resulting from bone and lymphoid tumor competition after an injection of plutonium.
