Physiologically based pharmacokinetic modeling of inhaled radon to calculate absorbed doses in mice, rats, and humans

Sakoda, Akihiro*   ; Ishimori, Yuu  ; Kawabe, Atsushi*; Kataoka, Takahiro*; Hanamoto, Katsumi*; Yamaoka, Kiyonori*

This is the first report to provide radiation doses, arising from inhalation of radon itself, in mice and rats. To quantify absorbed doses to organs and tissues in mice, rats, and humans, we computed the behavior of inhaled radon in their bodies on the basis of a physiologically based pharmacokinetic (PBPK) model. It was assumed that radon dissolved in blood entering the gas exchange compartment is transported to any tissue by the blood circulation to be instantaneously distributed according to a tissue/blood partition coefficient. The calculated concentrations of radon in the adipose tissue and red bone marrow following its inhalation were much higher than those in the others, because of the higher partition coefficients. Compared with a previous experimental data for rats and model calculation for humans, the present calculation was proved to be valid. Absorbed dose rates to organs and tissues were estimated to be within the range of 0.04 - 1.4 nGy/(Bq/m)/day for all the species.