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

Abstract

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.

Radiation and circulatory disease

“…There have been a number of analyses of the Mayak worker cohort in the last few years [32,33,65-68], based on a similar underlying dataset characterized by: (a) cohort (18,797 - 22,377 workers first employed by the Mayak Production Association (PA) 1948-1972 or 1948-1982); (b) disease endpoints (all circulatory disease, IHD, CeVD morbidity/mortality); (c) years of follow-up (to end 2005 or end 2008); and (d) dosimetry system (all MWDS 2008), which yield slightly different risk estimates, because of variations in these (and possibly other) criteria. Risk estimates are also of course somewhat discrepant in other analysis of this cohort which differ more significantly with respect to criteria (a)-(d) [69-71]. Here the most recent studies of IHD and CeVD are used, in particular the studies of Azizova et al [32] and Moseeva et al [33], which are cited in Table 4 and used as the basis of the meta-analysis.…”

Health Impacts of Low-Dose Ionizing Radiation: Current Scientific Debates and Regulatory Issues

“…Incidence of lower extremity arterial disease was positively associated in this cohort with total dose from external γ-rays and not associated with doses from internal α-radiation. 105 It should be noted, however, that these workers were exposed not in a low-dose but in a moderate-dose range (on average, 540 mGy for men and 440 mGy for women). Relative risk of cataract incidence was found to be the highest in workers exposed at doses above 2.0 Gy.…”

“…A dose–response relationship between α-radiation exposure and incidence of various cancerous and noncancerous disorders was observed in nuclear workers chronically exposed by inhalation to plutonium ( 239 Pu) in the Mayak Nuclear Enterprise (Chelyabinsk region, Russia). 98 - 120 For instance, the incidence of lung cancer corrected for smoking was 0.56, 0.59, and 0.83 at body burdens of 343, 1180, and 4200 Bq, respectively, in 500 nuclear workers relative to internal controls. Of note, the lung cancer incidence was linearly associated with cigarette smoking, with 2-fold risk of lung cancer in those workers who smoked 1 pack of cigarettes per day for at least 5 years.…”

Low- and moderate-dose non-cancer effects of ionizing radiation in directly exposed individuals, especially circulatory and ocular diseases: a review of the epidemiology

“…Russian Mayak nuclear worker cohort. The Mayak worker cohort has been subject to various recent analyses (Azizova et al 2014;Moseeva et al 2014;Simonetto et al 2014;Azizova, Grigorieva, et al 2015;Simonetto et al 2015;Azizova et al 2016;Azizova, Batistatou, et al 2018), of which the most recent studies of IHD and CeVD are used here (Moseeva et al 2014;, also a study of lower extremity arterial disease (Azizova et al 2016), and the Mayak part of a pooled analysis (with the Sellafield workers) (Azizova, Batistatou, et al 2018) which are cited in Table 1. There are significant trends with dose for IHD and CeVD morbidity, although the mortality trends for these endpoints are much lower, and generally non-significant (Moseeva et al 2014;Azizova, Batistatou, et al 2018) (Table 1), the reasons for which are discussed below.…”

“…Russian national mortality data is likely to be particularly unsound, with marked differences in disease coding practices over the country (Wasserman and Varnik 1998;Danilova et al 2016), and should therefore probably not be used for epidemiological analysis, in particular for any of the Russian worker studies considered here (Moseeva et al 2014;Azizova et al 2016;Kashcheev et al 2016;Kashcheev et al 2017). Mortality data on Mayak workers who had never left Ozyorsk city for another place of residence were derived only in Ozyorsk.…”