A biodosimetric approach for estimating radiation dose to the respiratory epithelium from inhaled radon progeny

Many individuals are exposed to α radiation from inhaled radon progeny; however, despite many estimates of exposure and cancer risk, uncertainties about the magnitude of exposure and the resultant cancer risk from inhaled radon progeny remain. Estimates of α dose to the respiratory epithelium from inhaled radon progeny were made by comparing the cytotoxic response of rat tracheal epithelial cells exposed to 238Pu α particles in vitro, where the dose is known, with the cytotoxic response of cells exposed to radon progeny in vivo, where the α radiation dose is not known. To estimate the α dose to cells exposed in vivo to radon progeny, we determined the in vitro α dose that gave the same relative survival obtained following in vivo exposures using colony-forming assays on isolated tracheal epithelial cells. By extrapolation from the in vitro dose-response curves for cytotoxicity, we concluded that tracheal epithelial cells received approximately 2.1 mGy of α radiation per Working Level Month (WLM) of radon progeny exposure. This approach provides a biologically based method for estimating the α dose to the respiratory tract epithelial cells from inhaled radon progeny. (author)