Effect of external irradiation on the clearance and fate of transuranic oxides deposited in rat lung

The authors initiated a series of studies to determine the fate of inhaled transuranic compounds in combination with external irrradiation. For the first study, rats were irradiated in the thoracic region with a neutron or gamma source at doses comparable to those used for radiotherapy. Two to five months later, they were also exposed to a suspension of 239PuO2 by inhalation or intratracheal instillation, and the clearance of radionuclide was compared to that in unirradiated rats. In a second study, rats received whole-body gamma exposures immediately before inhaling either 239Pu or 244Cm as high-fired oxides. Exposure to 0.31-0.39 C/kg (1200-1500 R) of gamma or 9.5 Gy neutron irradiation 2-5 months before inhalation inhibited the lung clearance of Pu, whereas whole-body irradiation immediately before inhalation exposure has little effect on clearance or translocation of Pu and Cm. (author)