A tissue distribution model for assessment of human inhalation exposures to 241AmO2.

A model useful for predicting lung retention and tissue distribution following human inhalation exposure to 241AmO2 has been formulated. The model is based on inhalation studies in beagles exposed to either monodisperse or polydisperse aerosols of 241AmO2. It also describes lung retention for several cases of accidental human inhalation exposure to 241Am adequately. The model incorporates an expression for solubilization of 241AmO2 deposited in lung which is based on physicochemical characteristics of the inhaled particles. Comparison of predictions from this model and those of the International Commission of Radiological Protection in ICRP Publication 30 shows some important differences. Lung retention patterns of inhaled 241Am in dogs and humans after inhalation of 241AmO2 are very similar and do not conform with predictions of the ICRP 30 model. Although use of the ICRP 30 model for calculation of annual limits of intake produces similar values to predictions made from our model, a more complete assessment of accidental human exposures to 241AmO2 and the risk to individual organs can be made using the retention and dosimetry model formulated from these studies in dogs.