Risks of non-cancer diseases at low and intermediate dose levels in the French cohort of nuclear workers: updated follow-up 1968-2014

International audienceIntroduction 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 badge-monitored for external radiation exposure has been followed-up for several decades. Recent results on risk of death from a panel of non-cancer diseases are presented.Methods A cohort of 80,348 nuclear workers employed by CEA, Orano, or EDF companies was assembled and followed-up for mortality from 1968 to 2014. Vital statuses and causes of death were obtained from national registries. Annual exposure to penetrating photons was reconstructed for each worker: recorded doses of ionizing radiation were converted into estimates of organ doses or Hp(10) doses. Poisson regression methods were used to estimate excess relative rates (ERR) of disease per unit of cumulative dose lagged by 10 years, adjusting for calendar year, age, sex, company, duration of employment, and socioeconomic status; 95% likelihood-based confidence intervals (CI) are reported.Results The 80,348 workers (86% of men) accrued 2,55 million of person-years, with a mean cumulative dose of 16 milliSievert (mSv). Mean attained age was 63 years and 80% of workers were alive at the end of the follow-up; 15,695 deaths were observed, including 61% from non-cancerous diseases. No association between cumulative dose and risk of mortality from all non-cancerous diseases was observed (ERR per Sv = 0.02; 95%CI: -0.48, 0.57; p = 0.934, n = 9,555) but a statistically significant linear dose-response relationship was observed for dementia and Alzheimer’s disease with absorbed dose to the brain.Conclusions The long follow-up makes this cohort informative with respect to the long-term risks following protracted exposure to low-dose ionizing radiation. The observed association between dementia mortality risk and ionizing radiation was not observed in previous analyses and should be viewed with caution