Risk of chronic bronchitis incidence in the extended cohort of Mayak workers first employed in 1948-1982

Results of the study of chronic bronchitis (CB) incidence among workers of the first in the Russian Federation nuclear production association Mayak PA first employed at one of the main facilities in 1948-1982 and followed up till the end of 2008. Radiogenic risks were estimated based on data on occupational radiation exposure provided by “Mayak Worker Dosimetry System - 2008”. A positive statistically significant association was found for CB incidence risk in the study cohort with absorbed lung doses from occupational radiation exposure. Excess relative risk (ERR/Gy) associated with external gamma-rays (including adjustments for sex, attained age, calendar period, plant, smoking status and alpha-radiation exposure) and its 95% confidence interval (CI) were 0.14 (95% CI: 0.02, 0.28) during 1961-2008 follow-up period; ERR/Gy associated with internal alpha-radiation (including adjustments for above listed non-radiation factors and gamma-rays) was 1.14 (95% CI: 0.41, 2.18). When the analysis included an adjustment for quantitative parameter of smoking habit, i.e. smoking index, rather than smoking status, and potential occupational hazards prior to Mayak PA employment, no significant association of CB incidence risk with external gamma-rays was observed while ERR/Gy of internal alpha-radiation was 1.19 (95% CI: 0.32, 2.53).