Mortality analysis in a cohort of medical workers exposed to low dose of ionizing radiation in France (the ORICAMs cohort)

International audienceIntroductionMedical staff is the largest group of workers occupationally exposed to ionizing radiation (IR). The health risks associated with occupational exposure to low doses of IR in the medical field have been investigated in several national cohorts, but to date no study has been carried out in France. The ORICAMs (Occupational Radiation Induced Cancer in Medical Staff) cohort aims to assess the all-cause mortality in medical radiation workers.MethodsThe ORICAMs cohort was set up in 2011 by the French Institute for Radiobiological Protection and Nuclear Safety (IRSN). It includes all medical staff monitored for IR exposure with at least one dosimetric record in the SISERI database (the national registry for monitoring IR exposure in workers) over the period 2002-2012. Causes of death were abstracted from death certificates and coded according to ICD-10. The follow-up ended on 31/12/2017. Standardized mortality ratios were calculated by cause of death to compare the mortality in the cohort to that in the French population, by gender, age group and age at first exposure.Results126,940 workers were included in the cohort (62% women, 38% men), of whom 2,387 deaths were recorded. Compared to the general population, a significant decrease in all-cause mortality was observed, consistent with the "healthy worker effect". Results will be detailed by cause of death, age group, age at first exposure and gender.ConclusionsThis first analysis of the ORICAMs cohort exhibited a decreased mortality in French medical radiation workers compared to national reference rates. However, these results from an analysis with an external reference to the cohort do not preclude the existence of a potential dose-response relationship between chronical low-dose exposure and cancer risk within the cohort. Further dose-response analyses based on individual exposure to IR will be performed to characterize radiation-associated cancer risks in the context of occupational exposure