Deposition and early disposition of inhaled 233UO2(NO3)2 and 232UO2(NO3)2 in the rat.

Little information exists on the metabolism and potential health effects of 233U and 232U, high-specific-activity U isotopes associated with Th breeder systems. This paper describes the distribution and retention of the two isotopes following inhalation of uranyl nitrate, a simulated process solution. The lungs of rats exposed to 233UO2(NO3)2 and 232UO2(NO3)2 aerosols contained from 7 to 23% of the total amount of U retained in the rat after a 30-min inhalation exposure. Uranium was translocated rapidly from the lung and was retained mainly in skeleton, kidney and liver. Amounts equivalent to from one-quarter to one-half the initial lung burden (ILB) of U were excreted in urine the first day after inhalation. Radiation dose estimates based on 233U and 232U retention kinetics indicate that lung and skeleton would be the target organs for delayed radiation effects.