Radon: A likely carcinogen at all exposures

Background: Radon is a well-established lung carcinogen that has been extensively studied. Very high concentrations can occur in some underground mines. Concentrations also tend to build up in homes. Materials and methods: Epidemiological studies of radon-exposed miners and of residential radon and lung cancer are reviewed. Quantitative estimates of the risk of lung cancer, based on the experience of the miners, are applied to residential radon exposures in the United Kingdom. Strategies for the prevention of lung cancer induced by residential radon are discussed. Results: Estimates are uncertain, but residential radon is probably responsible for about 2000 lung cancer deaths per year in the United Kingdom, or around 6% of the total, making it the second biggest cause after smoking. Over 80% of the deaths are estimated to occur at ages less than 75 and over 80% in smokers or ex-smokers. Around 90% of radon-induced deaths in the United Kingdom probably occur as a result of exposures to radon concentrations below the currently recommended action level of 200 Bq m(-3). Conclusions: Further work is needed to obtain more reliable estimates of the risk of lung cancer associated with residential radon and on the cost-effectiveness of various intervention strategies before the most appropriate policies can be developed for managing exposure to this natural carcinogen.