Abstract
Significant survival reduction was not observed at the lung dose of 0.16 Gy, but was correlated with early increase of lung carcinomas at the doses over 0.45 Gy after inhalation exposure of female Wistar rats to alpha-emitting plutonium (Pu) dioxide aerosols. These carcinomas were 70-80% among all the primary lung tumors, increased in a dose-dependent manner over 0.45 Gy, reaching the plateau of 90% at 6.6-8.5 Gy. As compared to the dose response curve for lung carcinomas from thoracic X-irradiated rats, the slope of the fit linear equation and the relative effectiveness for 50% incidence of carcinomas were approximately 11-times as high in Pu-exposure as those of thoracic X-irradiation. Microscopic numbers of lung tumor lesions were about 2-fold more in Pu-exposure, while the proportions of histopathological types were almost similar between Pu-exposure and X-irradiation. These results indicate that relative effectiveness for pulmonary carcinogenesis is greater in Pu-exposure than X-irradiation, whereas lung tumor types appear to originate from the same target epithelial cells. [J Radiat Res 44:394 (2003)]
