Exposure to natural background radiation and association with childhood leukemia incidence in France 1990-2007

Background Several observational studies have reported associations between childhood acute leukemia and exposure to natural background radiation (NBR), but literature on low-dose ionizing radiation and childhood leukemia is still inconsistent. Aims To study the association between NBR exposure and childhood leukemia incidence in France. Methods We performed an ecological study including the 8,623 incident cases of childhood leukemia registered from 1990 to 2007 by the National Registry of Hematological children Malignancies. NBR exposure of the administrative units was obtained from three databases of the Institute for Radiological Protection and Nuclear Safety; (1) the estimates of geogenic radon potential, mapped over the French territory; (2) the measurements performed in a nationwide radon survey consisting in more than 10,000 measurements of indoor radon concentrations and/or gamma exposure in French dwellings; (3) the measurements of gamma-rays recorded in the 1,191 sites of the national TLD based surveillance system. Results The analysis of the association between NBR exposure and childhood leukemia will be presented, for radon and gamma-ray exposures at the scale of the 36,590 Communes as well as that of the 348 Zones d’emploi and 95 Départements. Specific analyses will be conducted by type of leukemia and by age. Sociodemographic characteristics of the Communes will be accounted for. Conclusions The study will provide more precise estimates of the distribution of NBR exposure among French children. The size of the study and the contrasts of exposures will permit detailed analyses of the association between NBR and childhood leukemia incidence.