Risk of lower extremity arterial disease in a cohort of workers occupationally exposed to ionizing radiation over a prolonged period

In this study the incidence risk of lower extremity arterial disease (LEAD; international classification of diseases version 9 code 440.2) was assessed in a cohort of workers occupationally exposed to radiation over a prolonged period. The study cohort includes 22,377 workers of the Mayak Production Association (25% of whom are females) first employed at one of the main facilities in 1948-1982 and followed up to the end of 2008. Dose estimates used in the study are provided by Mayak Worker Dosimetry System 2008. The mean total dose from external gamma-rays is 0.54 Gy for males and 0.44 Gy for females. The mean absorbed liver dose from internal alpha-radiation due to incorporated plutonium is 0.23 Gy in males and 0.44 Gy in females. Relative risks and excess relative risks per unit dose (ERR/Gy) are calculated based on maximum likelihood. A total of 943 cases of LEAD are registered in the study cohort during the follow-up of 512,801 person-years. A significant association of LEAD incidence with total dose from external gamma-rays (based on a linear model) was revealed, and the ERR/Gy is 0.27 (95% confidence interval (CI) 0.11; 0.48). It turned out that a linear-exponential model provides a better fit of the data (∆AIC = 9.957). Inclusion of an adjustment for internal alpha-radiation dose resulted in the reduction of the ERR/Gy to 0.19 (95% CI 0.05; 0.39), but the risk remains significant. No association of LEAD incidence with dose from internal alpha-radiation was found in the study worker cohort. It is concluded that this study provides evidence for an association of LEAD incidence with dose from external gamma-rays taking non-radiation factors into account.

[Prevalence of aortal atherosclerosis in workers underwent occupational irradiation]

The authors evaluated prevalence of aortal atherosclerosis in dependence on radiation and non-radiation factors in workers underwent occupational prolonged irradiation.The study included 22,377 workers of nuclear industry enterprise "Mayak", with verified diagnosis of aortal atherosclerosis. Up to 31th December 2008, a total of 1,840 aortal atherosclerosis cases were registered in the examinees group. Aortal atherosclerosis prevalence appeared to depend reliably on sex, age, smoking habit (in males), alcohol consumption (in males) and arterial hypertension. Findings are that aortal atherosclerosis prevalence was higher in males and females underwent external gamma-irradiation of total dose over 0.5 Gy, in males and females underwent internal alpha-irradiation from incorporated plutonium of total absorbed radiation dose in liver over 0.025 Gy. Thus, aortal atherosclerosis prevalence in workers underwent occupational irradiation de- pended both on radiational and non-radiational factors.