Mortality in the French cohort of nuclear workers

Populations of nuclear workers are particularly relevant to study health effects of protracted exposures to low doses at low dose-rates of ionizing radiation. In France, a cohort of nuclear workers employed by the Commissariat a 1'energie atomique et aux energies alternatives (CEA), AREVA Nuclear Cycle (AREVA NC), or Electricite de France (EDF), and badge-monitored for external radiation exposure, has been followed-up for several decades. Annual exposure to penetrating photons was reconstructed for each worker. Standardized mortality ratios were calculated using national mortality rates as the reference. Estimates of radiation dose-mortality associations were obtained using linear excess relative risk models. Mortality of 59 004 workers was followed-up between 1968 and 2004, for an average of 25 years. The mean cumulative photon Hp(10) dose was 18.4 mSv in the whole cohort (median value: 2.1 mSv) and 25.7 mSv among exposed workers. At the end of the follow-up, workers were 56 years old on average and 6310 workers had died. A strong healthy worker effect was observed. Estimated dose-risk relationships were consistent with those from other worker studies for all solid cancers and leukaemia excluding chronic lymphocytic leukaemia, but remained associated to a large uncertainty. This cohort is the most informative study ever conducted in France among nuclear workers.