Radon progeny dosimetry in the rat lung.

Deposition, mucociliary clearance, and dosimetry for the inhalation of radon progeny in the rat lung have been simulated for a variety of inhalation conditions. Computations indicate that the exposure-dose conversion factor for the rat lung is approximately twice as high as the corresponding value for the human lung for the same exposure conditions. However, if typical aerosol characteristics are used for animal inhalation experiments and human indoor exposures, the resulting exposure-dose conversion factors are comparable, thereby suggesting similar lung cancer risks per unit exposure. The predicted relative effects of radon progeny disequilibrium and unattached fractions on bronchial doses agree with results from inhalation experiments with laboratory rats.