Bioassay model for estimating body burdens of 241Am from excretion analyses

A simple bioassay model for predicting the organ burdens of 241Am from excretion rates is presented for inhalation exposures. The model uses three compartments representing lung, liver and skeleton. The model was developed using data from studies in laboratory animals of inhaled or injected 241Am and was validated for people by comparison to cases of accidental inhalation exposures to 241Am. The data for people have a large amount of variability but indicate that the retention half-time of 241Am in liver is approximately 2 yr and in skeleton is approximately 30 yr. These parameters can be used in the model to estimate body and organ burdens from excretion rates after inhalation of 241Am or the model can be fitted to an individual's measured excretion rates.