How do we know radon causes lung cancer in humans?
Radon is classified as a Class A known human carcinogen according to the World Health Organization’s International Agency for Research on Cancer (IARC 1988). This classification is based on the strong evidence of lung cancers in underground miners. Data from 11 studies of radon-exposed underground miners show that about 40% of the 2,700 lung cancer deaths which occurred among 65,000 miners are due to radon according to the National Cancer Institute (NCI 1995). Among never-smokers, 70% of the lung cancer deaths are believed to be due to radon and 39% of the lung cancer deaths in smokers. While there are many differences in radon exposure conditions between mines and homes, it is notable that persons living in homes with radon above the EPA action level of 4pCi/L could accumulate radon exposures similar to underground miners. Miner studies show a consistent linear no-threshold relationship between lung cancer and radon exposure down to radon levels commonly found in homes. Epidemiology s
