Retention of inhaled 238PuO2 in beagles: a mechanistic approach to description.

Groups of Beagle dogs received inhalation exposure to one of three sizes of monodisperse or a polydisperse aerosol of 238PuO2. Periodic sacrifice of pairs of dogs through 4 yr after inhalation exposure provided data on the retention, translocation and mode of excretion of 238Pu. Fragmentation of 238PuO2 particles deposited in lung led to enhanced dissolution, translocation and excretion of 238Pu compared to previous studies using 239PuO2. A mechanistic simulation model was formulated to account for particle dissolution and fragmentation. This model provided adequate prediction of the time course of lung retention, uptake and retention in other organs and excretion. Predictions of the model provided more accurate description of the data than the Task Group on Lung Dynamics model incorporated in the ICRP Publication 30. The mechanistic model provided estimates of cumulative radiation dose to liver and bone that are a factor of five greater and to lung that are a factor of two less than predicted by the Task Group Lung Model.