Mortality among radiologic technologists in the united states (1926-1997). 2(nd) Follow up.
PURPOSE: To evaluate risk for all-cause and cause-specific mortality in a large, primarily female (73%) cohort of radiologic technologists.METHODS: The study consists of 145,915 radiation technologists, certified in the American Registry of Radiologic Technologists (1926-1982) and followed through 1997. Causes of death were obtained from death certificates or, more recently, through NDI Plus. Standardized Mortality Ratios (SMR) were computed and tests of homogeneity were performed to detect differences in mortality among causes. Poisson models were used to estimate risks using an internal comparison group.RESULTS: Significantly low SMRs were observed for all causes (0.76), all cancers (0.82), and diseases of circulatory system (0.69). Compared to U.S. women, the risk for breast cancer mortality bordered around unity (SMR 1.01, 95% CI 0.94-1.09). However, relative to all other cancers, breast cancer mortality was significantly increased (RSMR 1.24, p < 0.01). Elevated risk for breast cancer was associated with certification before 1940 (SMR 1.55, 95% CI 1.24-1.91), and duration of certification of 20-29 (SMR 1.21, 95% CI 1.06-1.37) and 30+ years (SMR 1.77, 95% CI 1.54-2.02). A 35% increase in leukemia risk was evident for women certified for a duration of 20-29 years and a 36% increase among women certified for 30+ years. Poisson analysis revealed a significant increase in breast cancer risk with increasing number of years certified among women first certified before 1940 (p < 0.001) and during 1940-49 (p = 0.05) compared to women first certified in 1950 or later.CONCLUSIONS: Preliminary findings of this study suggest increased breast cancer risk associated with occupational radiation exposures prior to 1950 and with long-term cumulative exposures. However, potential confounding by reproductive and other risk factors needs to be evaluated.