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Study of lung cancer risk and residential radon exposure

Exploitable results

The objective is to develop a strategy to combine world-wide evidence on the association between lung cancer risk and residential radon exposure using data based on air-based measurements, in order to increase the precision of risk estimates based on these studies. Analytic plan for world pooling of case-control studies of residential radon and lung cancer have been developed in co-operation with European and North American participants. In addition to the 13 studies from the European pooling exercise (WP1), the seven studies from the North America pooling exercise and two studies from China pooling exercise will also be included in the world pooling (China was outside the contract). The final data set is predicted to contain approximately 13000 cases of lung cancer and 22000 controls. This work-package will result in estimates of the association between residential radon exposure and risk of lung cancer based on virtually all the available worldwide evidence. The world pooling will be carried out with support from a contract under the EC 6th Framework Programme. The findings from this pooling will provide even more information on lung cancer risks from residential radon exposures and will form a valuable input to radon remediation and lung cancer prevention programmes world-wide.
Studies of underground miners have shown that lung cancer can be induced in humans by exposure to radon and its decay products. Several epidemiological case-control studies have also tended to show risks increasing with increasing indoor radon exposure, but the evidence has been less certain. To address the impact of residential radon exposure on the risks of lung cancer, a combined analysis of data from 13 studies conducted in nine European countries has been conducted, using air-based radon measurements of the homes where the study subjects lived during the previous 35 years. The analyses included a total of 7148 lung cancer cases and 14208 controls. The risk of lung cancer increased by 8.4% (95% confidence interval 3.0 to 15.8) per 100Bq/m3 metre increase in measured radon (p=0.0007). This corresponds to an increase of 16% (5 to 31) per 100Bq/m3 increase after adjustment for measurement errors in radon concentrations. The proportionate excess risk did not differ significantly with study, age, sex, or smoking. However, because smokers are already at higher risk for lung cancer, the absolute risks from radon are larger in smokers than in non-smokers. The results suggest that radon in homes is responsible for about 20000 lung cancer deaths in the EU each year. As a preliminary calculation, this is about 9% of the total lung cancer deaths in the EU and about 2% of cancer deaths overall.