Comparative biokinetics of plutonium and americium after inhalation of PuO2 and mixed oxides (U, Pu)O-2 in rat

Purpose: 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. Materials and methods: Lung clearance was measured in vivo by X-and gamma-r ay spectrometry. Retention of Pu and Am in femurs, liver and kidneys was me asured by oc-spectrometry. Results: Observed lung clearance was in the same range For all three powder s. Extra-pulmonary transfers were expressed as the percent of the initial d eep lung deposit (IDLD) measured 7 days after inhalation. After PuO2 exposu re, bone retention remained nearly constant throughout the 270-day experime nt. It was similar to 0.7% of the IDLD for Pu and Am. By contrast, a gradua l 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 SOL GEL. The retention reached maximal values between 180 and 270 days post-exp osure, which were 0.2 and 0.3% for MIMAS, and 1.2 and 2.8% for SOLGEL for P u and rim respectively. Conclusions: Different transfer rates of Pu and Am from the lung were obser ved depending on the chemical composition of the oxides and/or the method o f their preparation.