title: Comparisons of pulmonary carcinogenesis in rats following inhalation exposure to plutonium dioxide or X-ray irradiation.
abstract: Radiation-induced pulmonary carcinogenesis was compared in female Wistar rats following either inhalation exposure to alpha-emitting (239)PuO(2) aerosols, whole-body or thoracic X-ray irradiation. Dose-dependent survival reduction was correlated with increased malignant lung tumors at doses over 0.45 Gy, reaching the maximum incidence of 90% at 6.6-8.5 Gy in (239)Pu-exposed rats. While the differential dose responses for each histopathological type of tumors were noted, almost 70-80% were carcinomas among all of the primary tumors from (239)Pu-exposed rats. As the dose response curves for lung carcinomas were compared, the slope of the fit linear equation and the calculated relative effectiveness for 50% incidence of lung carcinomas were approximately 11-times as high in (239)Pu-exposure as those of thoracic X-irradiation. The numbers of tumor lesions distributed in the lung per tumor-bearing animal were about 2-fold more in (239)Pu-exposed rats, while the proportions of their histopathological types were similar between (239)Pu-exposure and X-irradiation. These results indicate that the magnitudes of the relative effectiveness or risk for pulmonary carcinogenesis are greater in (239)Pu-exposure than X-irradiation, and that radiation-induced lung tumors appear to originate mostly from the same target epithelial cells.
authors.affiliation: Internal Radiation Effects Research Group, Research Center for Radiation Safety, National Institute of Radiological Sciences, Japan. y_oghiso@nirs.go.jp
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Oghiso
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D000236:Adenoma / Q000145:classification / Q000209:etiology / Q000473:pathology; D000818:Animals; D002277:Carcinoma / Q000145:classification / Q000209:etiology / Q000473:pathology; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D019570:Inhalation Exposure / Q000009:adverse effects*; D008175:Lung Neoplasms / Q000145:classification / Q000209:etiology* / Q000473:pathology*; D008954:Models, Biological; D009381:Neoplasms, Radiation-Induced / Q000145:classification / Q000209:etiology* / Q000473:pathology*; D011005:Plutonium / Q000032:analysis / Q000633:toxicity*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D051381:Rats; D015996:Survival Rate; D014916:Whole-Body Irradiation / Q000379:methods; D014965:X-Rays / Q000009:adverse effects*
chemical_list: C026885:plutonium dioxide; D011005:Plutonium