Lung cancer attributable to indoor radon exposure in France using different risk models

Full text of publication follows: Radon exposure is omnipresent for the general public, but at variable levels, because radon mainly comes from granitic and volcanic subs oils as well as from certain construction materials. Inhalation of radon is the main source of exposure to radioactivity in the general population of most countries. In 1988, the International Agency for Research on Cancer declared radon to be carcinogenic for humans (lung cancer): radon is classed in the group 1. The exposure of the overall general population to a carcinogenic component led scientists to assess the lung cancer risk associated to indoor radon. The aim of this work is to provide the first lung cancer risk assessment associated with indoor radon exposure in France, using all available epidemiological results and performing an uncertainty analysis. The number of lung cancer deaths potentially associated with radon in houses is estimated for the year 1999 according to several dose-response relationships which come from either cohorts of miners or joint analysis of residential case-controls studies. The variability of indoor radon exposure in France and uncertainties related to each of the dose-response relationships are considered. The assessment of lung cancer risk associated with domestic radon exposure considers 10 dose-response relationships resulting from miners cohorts and case-control studies in the general population. A critical review of available data on smoking habits has been performed and allowed to consider the interaction between radon and tobacco. The exposure data come from measurements campaigns carried out since the beginning of the 1980's by the Institute for Radiation protection and Nuclear Safety and the Health General Directory in France. The French lung cancer mortality data are provided by the INSERM. Estimates of the number of attributable cancers are carried out for the whole country, stratified by 8 large regions and b y 96 departments for the year 1999 allowing to perform a sensibility analysis according to the geographical level of calculation. Uncertainties associated to risk coefficients and exposures have been quantified and it impact on risk estimates is calculated. The estimated number of deaths attributable to domestic radon exposure ranges from 1,234 (90 % uncertainty interval (UI): 593 2,156) to 3,108 (90 % UI: 2,996 3,221). The corresponding risk fractions range from 5 % (90 % UI: 2 % - 9 %) to 12.4 % (90 % UI: 11.9 % - 12.8 %). This work provides an adaptation of the classical risk assessment method integrating each of its step such as a discussion about the choice of the dose - response relationship. The data analysis considers the interaction between ionizing radiation and other risk factors and a quantification of uncertainties. This work provides new results showing the importance of the choice of the dose-response relationship and of the quantification of uncertainties in risk assessment. (authors)