Radon and skin cancer in southwest England: an ecologic study.

BACKGROUND Radon, a naturally occurring radioactive gas, is a carcinogen that causes a small proportion of lung cancers among exposed populations. Theoretical models suggest that radon may also be a risk factor for skin cancer, but epidemiologic evidence for this relationship is weak. In this study, we investigated ecologic associations between environmental radon concentration and the incidence of various types of skin cancer. METHODS We analyzed data for 287 small areas (postcode sectors) in southwest England for the years 2000-2004. Poisson regression was used to compare registration rates of malignant melanoma, basal cell carcinoma, and squamous cell carcinoma across mean indoor radon concentrations from household surveys. Analyses were adjusted for potentially confounding factors, including age, sex, population socioeconomic status, and mean hours of bright sunshine. RESULTS No association was observed between mean postcode sector radon concentration and either malignant melanoma or basal cell carcinoma registration rates. However, sectors with higher radon levels had higher squamous cell carcinoma registration rates, with evidence of an exposure-response relationship. Comparing highest and lowest radon categories, postcode sectors with mean radon ≥ 230 Bq/m(3) had registration rates 1.76 (95% confidence interval = 1.46-2.11) times those with mean radon 0-39 Bq/m(3). Associations persisted after adjustment for potential confounders. CONCLUSIONS This ecologic study suggests that environmental radon exposure may be a risk factor for squamous cell carcinoma. Further study is warranted to overcome ecologic design limitations and to determine whether this relationship is generalizable to national and international settings.