Radiological component of the Exposome, multiple exposures, risks of cancer and other chronic diseases in the Constances cohort (CORALE)

International audience; ContextThe whole population is exposed throughout its life to ionizing radiation (IR) at varying levels, via multiple natural and artificial sources, whether in the context of the residential environment, various activities (professional or other such as air travel) or for medical reasons (diagnostic or therapeutic procedures). The carcinogenic effects of IR are well documented at dose levels of 100 milliGrays (mGy) or higher. There is still controversy about the shape of the relationships between exposure and cancer risks at lower doses, called “low doses”. In addition, quantification of the effects of multi-exposure to IR and other cancer risk factors is poorly documented, with the exception of the interaction between tobacco and radon on lung cancer risk. Similarly, the relationships between exposures to IR at different stages of life (e.g., during childhood, puberty, etc.) and late health effects remain poorly characterized. Potential associations between low doses of IR and non-cancer chronic diseases also require better documentation. ObjectivesThe first objective of the CORALE project is to carry out the broadest possible reconstruction of doses of IR from environmental sources (radon, terrestrial and cosmic radiation, food, nuclear installations and other artificial sources), medical (diagnostic and therapeutic procedures) and occupational (nuclear workers but also other industries using radioactive sources, health professionals… ) received by participants in the Constances cohort since birth, following the logic of the exposome concept (for its radiological component). The second objective will be to estimate the risks of cancers and other chronic diseases potentially associated with the cumulative doses received (from several sources of IR and over time) taking into account the potential influence of the context of multi-exposures to other risk factors.MethodsIn order to reconstruct the annual doses due to radioactivity of natural and artificial origin received by each member of the Constances cohort since their birth, a large number of sources of radioactivity must be considered. Reconstructions related to environmental, medical and occupational exposures will be performed by different units of the IRSN in collaboration with the Constances cohort team. To do this, a questionnaire will be sent to cohort members who have already provided their residential histories. The statistical analyses (e.g., Cox models with time-dependent covariates) will be carried out at the IRSN epidemiology laboratory and will benefit from the expertise of radiobiologists, supporting the exploration of specific hypotheses and interpretations. The use of innovative regression methods on exposure profiles will be explored in collaboration with the University of Paris.PerspectivesCORALE is part of a broader long-term research programme, which will include the effects of other multi-exposures (e.g., IR and other environmental exposures) and the study of risk and exposure biomarkers through the Constances biobank, further complementing the application of the exposome concept through the study of within-body regulations following exposures. This program will help improve the characterization of the exposome and its relation with chronic diseases in the Constances cohort.