First mortality analysis in the French cohort of uranium millers (F-Millers), period 1968-2013.

purposeEpidemiological studies in cohorts of uranium millers can be informative to improve knowledge of the health effects of uranium, but are very rare. The aim of this study was to analyze, for the first time, mortality in a French cohort of uranium millers.

methodsThe F-Millers cohort includes permanent contract workers employed at least 6 months at French uranium milling plants. Vital status and causes of death were obtained from national registries between 1968 and 2013, in order to perform comparisons with French national and local mortality rates by computing standardized mortality ratios (SMRs) with 95% confidence intervals (95% CI).

resultsThe cohort includes 1291 workers. The average duration of follow-up is 32.1 years. At the end of follow-up, 448 workers were deceased and 13 lost to follow-up. We observed a significant deficit of mortality for all causes combined when the national reference was considered (SMR 0.81; 95% CI [0.74;0.89]), but no significant difference when the local reference was considered (SMR 0.97; 95% CI [0.88;1.07]). Significant excesses were observed only in a subgroup of 552 workers hired at the manufacturing unit, mainly when the local reference was considered.

conclusionNo significant excess of mortality was observed at the scale of the full cohort. The cause-specific excesses of mortality observed in the subgroup of workers hired at the manufacturing unit were based on small number of cases, but would warrant further investigations. Undertaking analytical studies and combined analyses of cohorts of uranium millers would help to study the influence of potential risk factors and obtain more precise results.