Collection, Validation, and Treatment of Data for a Mortality Study of Nuclear Industry Workers

Abstract

To investigate the long-term health effects of protracted occupational exposure to low levels of ionizing radiation, a combined facility mortality study was initiated for 118,588 workers hired between 1942 and 1982 by three Department of Energy facilities in Oak Ridge, Tennessee. The primary objectives of the study were: (1) to evaluate and compare the mortality experience of separate subcohorts delineated by facility of employment, and (2) to conduct detailed dose-response analyses of the combined facilities subcohort having potential for external radiation exposure. Presented here are issues involving validation and treatment of data for study members, and characteristics of their radiation exposure. To verify data accuracy a stratified random sample was chosen, and original source documents containing demographic and radiation exposure data were reviewed. Health physicists investigated monitoring policies and practices in place at each facility over the 42 years of follow-up (1943 to 1984) before combining exposure data over time and across facilities. One outcome of the validation process was limiting dose-response analyses to 28,347 potentially exposed white male employees of two of these facilities, who had received 90 percent of the total recorded external dose for the population, 405 Sv. Also revealed was possible underestimation of external doses for early years of operation at these same two plants. Procedures were developed for preliminary adjustments to these doses. Data for this cohort are available in the Comprehensive Epidemiologic Data Resource of the U.S. Department of Energy.