Mortality in nuclear workers of the French electricity company: Period 1968–2003

Abstract

Background We conducted a mortality study on a cohort of French nuclear workers employed at Électricité de France (EDF). A first cancer mortality analysis was based on the 1968–1994 period. This paper presents the results from a mortality analysis including nine additional years of follow-up without consideration of exposure, covering the 1968–2003 period. Methods The cohort includes 22,393 workers, 97% of whom are males. Employment data were updated using the EDF personnel file. Vital status was ascertained using the National Registry of Population and further completed using EDF personnel and pension files. Causes of death were obtained through the National Causes of Death file. Standardized mortality ratios (SMRs) were computed using national rates as references. Variations of all-cause and all-cancer SMRs were studied according to demographic and occupational characteristics. Results At the study end point (31/12/2003), 74% of workers were still in active service. Only 0.3% of workers were lost to follow-up. The median duration of follow-up was 20 years. Causes were ascertained for 96% of deaths. The total number of deaths was 874, 307 of which were cancer deaths. SMRs for all causes and cancers show a significant deficit compared to the French national mortality rates. No significant excess was observed for any of the cancer sites studied. Nonsignificant excesses were observed for pancreatic, pleural, kidney, and brain cancer. Significant variations of all-cause SMRs according to age at study entry and attained age were observed. Significant variations of all-cause and all-cancer SMRs according to education level at employment were observed, with a reduced SMR for a higher level of education. Conclusion There is a significant deficit of mortality compared to the general population, reflecting a strong healthy worker effect. Although nine years of follow-up were added, this cohort is made up of young workers, most of whom are still in active service. Regular updating of the follow-up of this cohort is planned, aiming for an occupational health surveillance of workers occupationally exposed to ionizing radiation in France.