Circulatory disease mortality among male medical radiation workers in South Korea, 1996–2019

OBJECTIVE: The aim of this study was to investigate the relationship between occupational radiation exposure and circulatory disease (CD) mortality among medical radiation workers. METHODS: The study included 53 860 male diagnostic medical radiation workers enrolled in the National Dosimetry Registry (NDR) between 1996 and 2011 in South Korea. NDR data were linked with mortality data obtained from the national registry at the end of 2019. Observed CD mortality rates in this population were compared to those in the general population using the standardized mortality ratio (SMR). The relative risk (RR) for occupational history was estimated by use of internal comparisons, and the excess relative risk (ERR) was used to quantify the radiation dose–response relationship. RESULTS: A total of 320 deaths due to CD were identified among 53 860 male medical radiation workers. The SMR of CD was significantly lower among male workers than the general population. A linear dose–response model provided an estimated ERR per 100 mGy for CD [0.85, 95% confidence interval (CI) -0.11–1.82], ischemic heart disease (1.18, 95% CI -0.69–3.05), and cerebrovascular disease (0.23, 95% CI -0.48–0.94) with a 10-years lag, showing no statistical evidence of a radiation dose–response relationship. Additional adjustments for non-radiation factors did not affect the findings on occupational radiation risk for CD mortality. Sensitivity analyses excluding workers employed <1 year or who had exposure to a cumulative badge dose of ≥1 mSv showed similar results. CONCLUSIONS: Occupational radiation doses were non-significantly positively associated with CD mortality among male diagnostic medical radiation workers. However, cautious interpretation is needed due to the limitations of short follow-up.