Comparative biokinetics of plutonium and americium after inhalation of PuO2 and mixed oxides (U, Pu)O2 in rat

To compare the biokinetics of Pu and Am in rat after inhalation of PuO2 and two (U, Pu) mixed oxides (MOX), referred to as MIMAS and SOLGEL. Lung clearance was measured in vivo by X-and y-ray spectrometry. Retention of Pu and Am in femurs, liver and kidneys was measured by alpha-spectrometry. Observed lung clearance was in the same range for all three powders. Extra-pulmonary transfers were expressed as the percent of the initial deep lung deposit (IDLD) measured 7 days after inhalation. After PuO2 exposure, bone retention remained nearly constant throughout the 270-day experiment. It was approximately 0.7% of the IDLD for Pu and Am. By contrast, a gradual increase was observed for the two MOX. After 7 days, bone retention of Pu and Am was respectively 0.05 and 0.08% for MIMAS, and 0.2 and 0.6% for SOLGEL. The retention reached maximal values between 180 and 270 days post-exposure, which were 0.2 and 0.3% for MIMAS, and 1.2 and 2.8% for SOLGEL for Pu and Am respectively. Different transfer rates of Pu and Am from the lung were observed depending on the chemical composition of the oxides and/or the method of their preparation.