A MORTALITY STUDY OF EMPLOYEES OF THE NUCLEAR INDUSTRY IN OAK-RIDGE, TENNESSEE

An analysis was conducted of 27,982 deaths among 106,020 persons emplo yed at four Federal nuclear plants in Oak Ridge, Tennessee, between 19 43 and 1985. The main objectives were to extend the evaluation of the health effects of employment in the nuclear industry in Oak Ridge to i nclude most workers who were omitted from earlier studies, to compare the mortality experience of workers among the facilities, to address m ethodological problems that occur when individuals employed at more th an one facility are included in the analysis, and to conduct dose-resp onse analyses for those individuals with potential exposure to externa l radiation. All-cause mortality and all-cancer mortality were in clos e agreement with national rates. The only notable excesses occurred fo r white males for lung cancer [standardized mortality ratio (SMR) = 1. 18, 1,849 deaths] and non-malignant respiratory disease (SMR = 1.12, 1 ,568 deaths). A more detailed analysis revealed substantial difference s in death rates among workers at the Oak Ridge plants. Evaluation of internally adjusted log SMRs using Poisson regression showed that work ers employed only at Tennessee Eastman Corporation or K-25 and at mult iple facilities had higher death rates than similar workers employed o nly at X-10 or Y-12, and that the differences were primarily due to no n-cancer causes. Analysis of selected cancer causes for white males in dicated large differences among the workers at the different facilitie s for lung cancer, leukemia and other lymphatic cancer. Dose-response analyses for external penetrating radiation were limited to a subcohor t of 28,347 white males employed at X-10 or Y-12. Their collective rec orded dose equivalent was 376 Sv. There was a strong ''healthy worker effect'' in this subcohort - all-cause SMR = 0.80 (4,786 deaths) and a ll-cancer SR IR = 0.87 (1,134 deaths). Variables included in the analy ses were age, birth cohort, a measure of socioeconomic status, length of employment, internal radiation exposure potential and facility. For external radiation dose with a 10-year lag, the excess relative risk was 0.31 per Sv (95% CI = -0.16, 1.01) for all causes and 1.45 per Sv (95% CI = 0.15, 3.48) for all cancer. The estimated excess relative ri sk for leukemia was negative but imprecisely determined. A preliminary dose adjustment procedure was developed to compensate for missing dos e but not other dosimetry errors. Results of the analyses using the ad justed doses suggest that the effect of missing dose is an upward bias in dose-response coefficients and test statistics. (C) 1997 by Radiat ion Research Society.