Residential radon exposure and cancer.

Radon is an established human lung carcinogen naturally released as an odorless, colorless gas from soil and rocks. It is a major environmental source of ionizing radiation and can cause oxidative damage to DNA, increasing the risk of lung cancer. Although the association between radon and lung cancer is well established, the association between radon and other cancers is not. Based on reported studies, there is no consistent evidence indicating an association between radon and non-solid and solid cancers, but limited literature, heterogenous study design, and confounding variables preclude definitive conclusions. More research is needed to evaluate the association between residential radon and non-lung cancers, particularly with regard to skin cancer, central nervous system (CNS) cancer, renal, and stomach cancer, in which existing literature suggests potential associations with residential radon may exist. However, the literature largely demonstrates that lung cancer is the primary concern associated with residential radon exposure; the lack of association with nonlung cancers could reflect the lack of studies which have an adequate sample size, establish accurate levels of radon exposure, and control for confounders. These results should be considered in residential radon mitigation efforts which should focus on smokers with high radon exposures.