Soft tissue tumors induced by monomeric 239Pu.

Individual records of soft tissue tumor occurrence (lifetime incidence) among 236 beagles injected with 239Pu citrate as young adults and 131 comparable control beagles given no radioactivity enabled us to analyze the possible effects on soft tissue tumor induction resulting from internal exposure to 239Pu. A significant trend was identified in the proportion of animals having malignant liver tumors with increasing radiation dose from 239Pu. There was also a significant difference in the relative numbers of both malignant liver tumors (3.2 expected, 22 observed) and benign liver tumors (18.1 expected, 66 observed). Malignant tumors of the mouth, pancreas, and skin were more frequent among controls than among the dogs given 239Pu as were all tumors (malignant plus benign) of the mouth, pancreas, testis, and vagina. For all other tumor sites or types, there was no significant difference for both malignant and all (malignant plus benign) tumors. Mammary tumor occurrence appeared not to be associated with 239Pu incorporation. We conclude that the only soft-tissue neoplasia induced by the intake of 239Pu directly into blood is probably a liver tumor.