Cancer admission and mortality in workers exposed to ionizing radiation in Korea

Objective: Cancer mortality and morbidity are described for the first time in all Korean workers exposed to ionizing radiation. Methods: Based on hospital admissions, Standardized Rate Ratios (SRR) and Standardized Mortality Ratios (SMR) were modeled with Poisson regression. Results: Cancer admissions during 2000 to 2005 were low compared with autoworkers with the exception of nuclear power workers (SRR = 1.13, 95% CI = 0.94-1.36). Thyroid cancer was statistically significantly elevated in women radiation workers in medical (SRR = 2.90, 95% CI = 1.05-7.94) and research institutions (SRR = 3.91, 95% CI = 1.36-11.0) and industry (SRR = 5.07, 95% CI = 1.56-15.6), and in all nuclear power workers (SRR = 2.59, 95% CI = 1.33-5.13), and there was a significant association with dose (ERR = 20.4 per Sv, 90% CI = -8 to 60, one-tailed P = 0.049). The 935 deaths revealed a healthy worker effect for all causes (SMR = 0.58, 95% CI = 0.54-0.62) and all-cancer (SMR = 0.73, 95% CI = 0.64-0.82). Lung cancer (SMR = 0.77, 95% CI = 0.55-1.05) and leukemia (SMR = 0.59, 95% CI = 0.28-1.06) mortalities were also less than expected. Compared with autoworkers, radiation workers displayed decreased all-cause mortality except for nuclear power workers (statistically not significant). Conclusions: ERRs as high as 300 per Sv appear to be ruled-out in this population with regulated exposure to ionizing radiation while ERRs as high as 100 per Sv are not.