Risk of Angina Pectoris in a Cohort of Nuclear Workers

Purpose: To assess the incidence risk of angina pectoris (ICD-10 code: I20) in a cohort of workers who had chronic occupational exposure taking into account non-radiation factors: sex, age, smoking status, alcohol consumption, body mass index (BMI), arterial hypertension (AH), diabetes mellitus (DM). Material and methods: The study cohort included 22,377 workers of the nuclear energy enterprise ‒ the Mayak Production Association (PA) ‒ who had been hired during 1948‒1982 and followed up until the end of 2018. The vital status at the end of the follow-up period is known for 95 % of the cohort members, of whom 67.2 % died, .and 32 % are alive. The presented study utilizes the MWDS-2013 (Mayak Worker Dosimetry System-2013) individual dose estimates of external and internal exposure. Mean cumulative liver absorbed dose of external gamma-exposure was 0.45 (0.65) Gy ‒ in males (mean(standard deviation)) and 0.37 (0.56) Gy ‒ in females. Mean cumulative dose of internal alpha-exposure to the liver made up 0.18 (0.65) Gy and 0.40 (1.92) Gy, respectively. The analysis included the calculation of relative risks (RR) and excess relative risk per unit dose (ERR/Gy) with the Poisson regression using the AMFIT module of the EPICURE statistical software package. Excess relative risk (ERR), i.e. the relative risk minus one, was described with the help of the linear dependence on the external dose adjusted for non-radiation factors (via stratification) and internal dose, as well as on the internal dose adjusted for the non-radiation factors and external dose. 95 % confidence intervals (CI) and statistical significance (p-values) were calculated with maximum likelihood methods. All the criteria of statistical significance were two-sided. The differences were considered statistically significant at p < 0.05. Results: A statistically significant linear dependence of the angina pectoris incidence on the cumulative liver absorbed dose of external gamma-exposure once adjusted for non-radiation factors (sex, attained age, calendar period, smoking status, alcohol consumption) and internal alpha-exposure dose has been established both for males and females. Conclusion: This is the first study of the angina pectoris incidence risk in the cohort of workers who had chronic occupational exposure that brings forward evidence of the relationship with the ionizing radiation.