Medical Radiology and Radiation Safety. 2018. Vol. 63. No. 4. P. 15-21

RADIATION MEDICINE

DOI: 10.12737/article_5b83b0430902e8.35861647

Risk Assessment of Senile Cataract Incidence in a Cohort of Nuclear Workers of Mayak Production Association

T.V. Azizova¹, E.V. Bragin¹, N. Hamada², M.V. Bannikova¹

1. Southern Urals Biophysics Institute, Ozyorsk, Chelyabinsk region, Russia, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. ; 2. Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, Tokyo, Japan

T.V. Azizova - Deputy Director, Head of Clinical Dep., PhD Med., ICRP Member, UNSCEAR Member; E.V. Bragin - Junior Researcher; N. Hamada - Researcher, PhD, ICRP Member; M.V. Bannikova - Junior Researcher

Abstract

Purpose: To estimate incidence risk for senile cataracts in a cohort of workers employed at nuclear production facility, that were occupationally exposed to radiation taking into account non-radiation risk factors.

Material and methods: Senile cataract incidence (cataracts) is studied in the cohort of Mayak PA workers first employed at one of the main facilities (reactors, radiochemical or plutonium production plants) during 1948-1982 (22,377 individuals). All members of the study cohort were occupationally exposed to gamma-rays or neutrons over a prolonged period. Absorbed doses from external and/or neutron exposure used in the study were provided by MWDS-2008. Relative risk (RR) and excess relative risk per unit dose (ERR/Gy) were estimated based on maximum likelihood using AMFIT module of EPICURE software.

Results: 4159 cataract diagnoses were verified in the study cohort of workers during 482217 person-years of follow-up. The majority of cataracts were diagnosed in cohort members included in the age group 61-70 years old in both males and females. The mean age at cataract diagnosis was 63.1 ± 0.2 years in males and 64.8 ± 0.2 years in females, respectively. RR of cataract incidence was statistically significant in all dose categories when compared to a reference category (0-0.25 Gy) and increased with increasing dose from external gamma-rays and was the highest in workers exposed to external gamma-rays at doses exceeding 2.0 Gy (1.61 95 % CI: 1,41-1,83). Significant linear association of cataracts with dose from external gamma-rays was observed with ERR/Gy = 0.28 (95 % CI: 0.20, 0.37). The risk estimate varied slightly with inclusion of additional adjustments for different non-radiation factors (smoking status and alcohol consumption, smoking index, hypertension, body mass index, severe myopia diagnosed). After adjusting for dose from neutrons ERR/Gy of external gamma-rays for cataracts increased considerably (0.31; 95 % CI: 0.22, 0.40). Significant ERR/Gy of external gamma-rays for senile cataract was revealed in both male and female workers of the study cohort, however the variations between the sexes were insignificant (p = 0.09). ERR/Gy of external gamma-rays for senile cataract was significant in all age groups except for workers under 40 years, but the differences among the age groups were insignificant (p > 0.5).

Conclusion: Risk of senile cataract incidence in the cohort of Mayak PA workers, occupationally exposed to radiation over prolonged periods, was significantly associated with dose from external gamma-rays.

Key words: risk, incidence, senile cataracts, external radiation, staff of Mayak PA, prolonged exposure

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For citation: Azizova TV, Bragin EV, Hamada N, Bannikova MV. Risk Assessment of Senile Cataract Incidence in a Cohort of Nuclear Workers of Mayak Production Association. Medical Radiology and Radiation Safety. 2018;63(4):15-21. Russian. DOI: 10.12737/article_5b83b0430902e8.35861647

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