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.