Mortality from various diseases of the circulatory system in the Russian Mayak nuclear worker cohort: 1948-2018.

The paper reports on findings of the study of mortality from diseases of circulatory system (DCS) in Russian nuclear workers of the Mayak Production Association (22,377 individuals with 25.4% of females) who were hired at the facility in 1948-1982 and followed up until end-2018. Using the AMFIT module of EPICURE software, relative risks and excess relative risks per unit absorbed dose (ERR/Gy) for the entire Mayak cohort, the subcohort of workers who were residents of the dormitory town of Ozyorsk and the subcohort of migrants from Ozyorsk were calculated based on maximum likelihood. The mean cumulative liver absorbed gamma-ray dose from external exposure was 0.45 (0.65) Gy (mean (standard deviation) gray) for males and 0.37 (0.56) Gy for females. The mean cumulative liver absorbed alpha dose from internal exposure to incorporated plutonium was 0.18 (0.65) Gy for males and 0.40 (1.92) Gy for females. By the end of the follow-up, 6019 deaths from DCS as the main cause of death were registered among Mayak PA workers (including 3828 deaths in the subcohort of residents and 2191 deaths in the subcohort of migrants) over 890,132 (622,199/267,933) person-years of follow-up. The linear model that took into account non-radiation factors (sex, attained age, calendar period, smoking status and alcohol drinking status) and alpha radiation dose (via adjusting) did not demonstrate significant associations of mortality from DCS, ischemic heart disease (IHD) and cerebrovascular disease (CeVD) with gamma-ray exposure dose in the entire cohort, the resident subcohort and the migrant subcohort (either in males or females). For the subcohort of residents, a significant association with gamma dose was observed for mortality from ischemic stroke in males with ERR/Gy=0.43 (95% CI 0.08; 0.99); there were no significant associations with liver absorbed gamma dose for any other considered outcomes. As for internal exposure, for males no significant associations of mortality from any of the DCS with liver absorbed alpha dose were observed, but for females positive associations were found for DCS (the entire cohort and the resident subcohort) and IHD (the entire cohort) mortality. No significant associations of mortality from various types of DCS with neutron dose were observed either in males or females, although neutron absorbed doses were recorded only in 18% of the workers.