Abstract
For the risk estimate of radon exposure, the biological effects for the tracheal epithelial cells were examined by in vitro exposure to radon. The dosimetric evaluation of the absorbed dose to basal cells of the bronchial epithelium per unit exposure gives 9 nGy/(h Bq/m3) for average indoor radon conditions (UNSCEAR 2000). Recent epidemiological report indicates that the risk of lung cancer increased by 8.4 % per 100 Bq/m3. When an equilibrium equivalent factor is assumed to be 0.4, the absorbed dose rate is 360 nGy/h. The experimental dose rate of alpha rays is several mGy/min as usual. Therefore, there is a great difference between environmental and experimental dose rate. Our exposure system produces environmental dose rate as nGy/h level. For radon exposure of cells, a ceramic radon source that was developed for radon experimental research was used. The radon gas was injected to the incubator through the filter. The absorbed dose was evaluated by using energy spectrum data of the irradiated alpha rays to the cells. The tracheal epithelial cells were isolated from Wister rat (WM/NIRS), and cultured by the air-liquid interface (ALI) method. This culture method is expected to be especially useful for simulation of exposure to radon. The biological effects were examined among several dose rate of alpha rays.
