A Radon Exposure Experiment of Rats and Mice

The exposure experiment of experimental animals was carried at a level of about 0.01 μCi radon/ml of chamber air. The concentration of radon was measured by a double screen ionization chamber. The concentration of dust free daughters in the chamber is decreased by radioactive decay, attachment to dust particles and deposition to the chamber wall. To express the rate of decrease, the attachment constant kp and the deposition constant kw were introduced in addition to the radioactive decay constant. The values of kp and kw were experimentally obtained by using a semiconductor detector installed on the chamber wall. The diffusion constant of daughter atoms estimated from the deposition constant kw was in good agreement with those obtained by other methods. The absorbed lung doses given to rat and mouse were 8.0 and 18.9 rads respectively, when radon was introduced into the test chamber at a level of 0.01 μCi/ml. The retention efficiency of the lung was approximately 2%9 for rat and mouse.