Although human epidemiological data provides the most important basis for assessing risks of radon exposure, additional animal studies have clearly demonstrated that radon is a lung carcinogen. The animal studies provided important information on the exposure-response relationship, the effect of exposure rate on cancer risk, and the potential effect of simultaneous exposure to radon and other contaminants on the radon-lung cancer relationship. Experimental animal studies conducted on rats in mines for more than 50 years yielded the following results:
Exposure to ore dust or diesel fumes simultaneously with radon did not increase the incidence of lung tumors above that produced by radon exposures alone.