Characterisation of radon risks in regions: raising stake holders' awareness of an underestimated public health issue

We spend 90 per cent of our life in buildings and radon is a proven carcinogen agent. However, in France a debate is ongoing among potential stake holders as to whether radon has a public health impact or not. In the regions where radon is a potential issue, the stake is to inform the various actors (including the population) of the scientific level of evidence on the effects of radon exposure, to assess its public health impact, to target actions while at the same time giving the opportunity to those actors to assess the remaining uncertainties. This task is incumbent upon the 'Cellules interregionales d'epidemiologie' (Inter regional Epidemiology Centres). Through the synthesis of studies conducted in two French regions with a high potential for radon, this article presents the approach, its methodology, its limitations and interests in management and delineates ways of improvements. The two studies were conducted in Brittany and in Corsica on the basis of results of a terms of campaign related to indoor radon by the Institute of Radioprotection and Nuclear Safety and the Ministry of Health. The risk fraction as well as the annual number of lung cancer deaths attributable to lifelong radon exposure were estimated for crude adjusted distributions based on the B.E.I.R. VI model (biological effects of ionizing radiation), which is a reference for experts. For mean exposures of 98 Bq/m3 and of 197 Bq/m3 an attributable risk fraction of respectively 20% and 30% was observed. Results show that in regions with a real radon potential, at least 50% of the attributable risk is due to concentrations above 100 Bq/m3. When reducing exposure in case levels exceed 200 or 400 Bq/m3 to lower levels, a significant efficiency on the safety health impact in those regions is observed. On the basis of such models, policy choices could be drafted and quantified while introducing more realistic hypotheses on the main factors that can determine the success of action policies intended to reduce indoor radon levels. It would be easier to optimize policy and technical choices in terms of actions against radon. (author)