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Report of epidemiologic analyses performed for Rocky Flats production workers employed between 1952-1989.
Ruttenber AJ; Schonbeck M; Brown S; Wells T; McClure D; McCrea J; Popken D; Martyny J
NIOSH 2002 Jun; :1-46
We identified a cohort of 16,303 production era workers employed at the Rocky Flats Plant for six months or more between 1952 and 1989, for whom we assembled data on dates of birth and hire, and vital status. For this cohort, we corrected data for annual external penetrating radiation doses, assembled data for systemic deposition of plutonium-239 and -240 and, with a job exposure matrix, estimated exposures to asbestos and nine toxic chemicals. Standardized mortality ratios (SMRs) for the production era cohort were significantly lower than expected for all causes of death and all deaths with cancer as an underlying cause. Elevated SMRs were noted for cancers of the stomach, rectum, brain and other central nervous system sites, connective and other soft tissue, as well as for unspecified neoplasms of the nervous system and unspecified anemias. The SMR for lung cancer was not elevated. Only the elevated SMR for unspecified neoplasms of the nervous system was statistically significant (p<0.05) when Colorado mortality rates were used to compute the expected number of cases. Because of the strong healthy-worker effect and confounding by multiple variables, more analyses must be conducted to clarify relations between exposures and causes of death. Matching the production era cohort with data from a statewide cancer registry identified some cancers sites that have larger numbers of incident cases than mortality cases. We are continuing to examine the strengths and weaknesses of analyses of cancer incidence for occupational cohorts. We also conducted a nested case-control study to investigate associations between lung cancer mortality and lung dose from internal exposure to plutonium, americium, and uranium isotopes. Lung cancer deaths (n=180) were identified from death certificates and individually matched to 720 controls on birth date and gender, using incidence density sampling. We identified statistically significant risks for cumulative internal lung doses greater than 400 mSv, but estimates of risks for high dose categories are not stable, and the influence of a number of confounding variables is complex. We identified age at first internal lung dose as a risk factor among workers with internal lung doses, with older workers being at higher risk than younger workers. Workers first hired between 1960 and 1967 were at significantly elevated risk and length of employment was inversely related to risk. No significant associations were found between lung cancer mortality and cumulative external penetrating radiation dose, or cumulative exposures to asbestos, beryllium, hexavalent chromium, or nickel. Additional cohort-based analyses with improved internal dosimetry are needed to clarify the risks for lung cancer from internal exposures received by Rocky Flats workers. Estimates of risk per unit dose from these analyses can be compared with estimates for plutonium workers in Russia and be used to determine whether with current radiation protection standards are adequately protective.
Radiation effects; Radiation exposure; Plutonium compounds; Mortality data; Cancer; Neoplasms; Statistical analysis; Humans; Lung burden; Dosimetry; Asbestos dust; Beryllium compounds; Hexavalent chromium compounds; Nickel compounds; Radiation protection
Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, 4200 E. 9th Avenue, Campus box B-119, Room Number MS-1609, Denver, CO 80262
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Research Tools and Approaches: Cancer Research Methods
National Institute for Occupational Safety and Health
Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, Colorado
Page last reviewed: March 3, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division