| These experiments were designed to determine if ('238)PuO(,2), due to its higher specific activity and attendant aggregate recoil, undergoes higher transfer through a membrane filter into an interstitial human alveolar lung fluid simulant than ('239)PuO(,2). The rate at which such transfer occurs was determined in an in-vitro chamber designed to simulate residence characteristics of particles of insoluble plutonium oxides in human alveolar interstitium. The ratio of the rate of ('238)Pu/('239)Pu transfer was 138 (+OR-) 76%.;Calculations were performed to assess the importance of this finding in terms of the internal dosimetry of insoluble ('238)Pu using methods and models recommended by the International Commission on Radiological Protection. Three cases were evaluated, namely integral 50-year dose commitment, urinary excretion after single acute intake and urinary excretion rate during chronic constant intake. It was found that integral 50-year dose commitments were not influenced by the rate of plutonium transfer from the pulmonary compartment to blood.;The evaluation of calculated urinary excretion data after a single acute inhalation intake showed that in the early period, up to about 30 days post exposure, urinary excretion of ('238)PuO(,2) may be 2 to 10 times higher than the urinary excretion rate for ('238)PuO(,2) predicted by the ICRP reference model. From about 50 days to approximately 1000 days the calculated urinary excretion rate for ('238)PuO(,2) may be lower than that predicted by the reference model by a factor of 2 to 10. In the case of chronic constant intake the calculated urinary excretion rate for ('238)PuO(,2) may be up to a factor of 2 higher than that predicted by the reference ICRP Model. |
