Silver-SR; Bertke-SJ; Hein-MJ; Daniels-RD; Fleming-DA; Anderson-JL; Pinney-SM; Hornung-RW; Tseng-C-Y
Occup Environ Med 2013 Jul; 70(7):453-463
OBJECTIVES: To examine mortality patterns and dose-response relations between ionising radiation and mortality outcomes of a priori interest in 6409 uranium workers employed for at least 30 days (1951-1985), and followed through 2004. METHODS: Cohort mortality was evaluated through standardised mortality ratios (SMR). Linear excess relative risk (ERR) regression models examined associations between cause-specific mortality and exposures to internal ionising radiation from uranium deposition, external gamma and x-ray radiation, and radon decay products, while adjusting for non-radiologic covariates. RESULTS: Person-years at risk totalled 236,568 (mean follow-up 37 years), and 43% of the cohort had died. All-cause mortality was below expectation only in salaried workers. Cancer mortality was significantly elevated in hourly males, primarily from excess lung cancer (SMR=1.25, 95% CI 1.09 to 1.42). Cancer mortality in salaried males was near expectation, but lymphohaematopoietic malignancies were significantly elevated (SMR=1.52, 95% CI 1.06 to 2.12). A positive dose-response relation was observed for intestinal cancer, with a significant elevation in the highest internal organ dose category and a significant dose-response with organ dose from internal uranium deposition (ERR=1.5 per 100 microGy, 95% CI 0.12 to 4.1). CONCLUSIONS: A healthy worker effect was observed only in salaried workers. Hourly workers had excess cancer mortality compared with the US population, although there was little evidence of a dose-response trend for any cancer evaluated except intestinal cancer. The association between non-malignant respiratory disease and radiation dose observed in previous studies was not apparent, possibly due to improved exposure assessment, different outcome groupings, and extended follow-up.
Radiation; Radiation-exposure; Radiation-facilities; Worker-health; Employee-exposure; Employee-health; Mortality-data; Mortality-rates; Ionizing-radiation; Uranium-compounds; Dose-response; Mathematical-models; Risk-analysis; Epidemiology; Gamma-radiation; X-ray-absorption; Cancer; Cancer-rates; Lung-cancer; Men; Lymphatic-cancer; Intestinal-cancer; Malignancy; Exposure-assessment
Sharon R Silver, Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, IWSB, 4676 Columbia Parkway, Mailstop R-15, Cincinnati, OH 45226, USA
Occupational and Environmental Medicine