Cancer mortality among two different populations of French nuclear workers.

PURPOSE: The aim of this paper is to study the effect of external photon radiation on the mortality of two populations of French nuclear workers: workers exposed only to external photon radiation and workers potentially exposed also to internal contamination or to neutrons.

METHOD: External photon radiation has been measured through individual dosimeters. Potential exposure to internal contamination or to neutrons has been assessed by experts on the basis of quantitative measurements or of worksite and type of activity. The mortality observed in each population was compared with that expected from national mortality statistics, by computing standardized mortality ratios. Dose-effect relationships were analyzed through trend tests and log-linear Poisson regressions.

RESULTS

14,796 workers were exposed only to external photon radiation; 14,408 workers were also potentially exposed to internal radiation or to neutrons. Between 1968 and 1994, the number of deaths is respectively, 645 and 1,197. The mean external photon dose was respectively, 3.7 and 12.9 mSv. Similar Healthy Worker Effects were observed in the two populations (SMR = 0.59). SMR of 2.41 90% CI [1.39-3.90] was observed for malignant melanoma among workers of the second population. Significant dose-effect relationships were observed: among workers exposed only to external photon radiation for leukemia except CLL and in the other population, for cancers and other diseases related to tobacco or alcohol consumption.

CONCLUSIONS

Results differed between the two populations. The increase in leukemia risk with dose in the first population will have to be confirmed with extended follow-up. In the other population, results may have been confounded by alpha-emitters inhalation, tobacco, or alcohol consumption.