The effects of small doses of ionizing radiation in the development of the incidence of diseases of the digestive organs in persons evacuated from the 30-kilometer zone of the Chornobyl NPP during 1992-2016. Epidemiological observation

Objective: Epidemiological assessment of the risks of developing non-neoplastic diseases of the digestive organs in evacuees from the 30-kilometer zone of the Chornobyl nuclear power plant in 1992–2016, analysis of the impact of ionizing radiation in small doses. Materials and methods: Epidemiological studies were conducted in a cohort of 4501 adults evacuated from the 30-kilometer zone of the Chornobyl nuclear power plant, with the presence of reconstructed effective doses of external ionizing radiation in the range of 0.001 Sv ÷ 0.38 Sv. The total cohort of subjects was stratified into 2192 individuals with exposed doses in the range of 0.001 Sv ÷ 0.05 Sv (IG) (internal control) and 2.309 individuals with exposed doses in the range of 0.051 Sv ÷ 0.38 Sv (EG). Epidemiological indicators used are absolute risk (AR), relative risk (RR) with 95% (±CI) confidence intervals (changes in risk values at the level of significance (p<0.05), attributive risk (ATR). Calculations were made by the number of people-years at risk during the years of observation (diseases detected for the first time per 103 person-years) The effect (of diseases) per unit value of the factor (1 Sv) (dose-effect) was determined by the excesses of the relative risk (ERR, 95% CI) with a confidence interval and the attributive risk (ATR, %) with the percentage of exceeding the absolute risk in the studied EG compared to IG. Research results. As a result of epidemiological studies, the role of small doses of ionizing radiation in the formation of digestive tract pathology in adults which were evacuated from the 30-kilometer zone of the Chernobyl nuclear power plant during the post-accident period was revealed. A significant excess of absolute, attributive and relative risk indicators was determined in patients which were exposed to effective doses in the range of ˂ 0.051 Sv ÷ 0.38 Sv. The highest absolute risk indicators were found in the groups «Diseases of the oral cavity, salivary glands and jaws» (K00-K14) and «diseases of the esophagus, stomach and duodenum» (K20-K31). Conclusions. Small doses of ionizing radiation have a special effect on the nature and intensity of the development of digestive organs’ pathologies in people, which were evacuated from the 30-kilometer zone of the Chоrnobyl nuclear power plant. However, in order to estimate the share of this pathology’s contribution to the overall morbidity, it is necessary to conduct additional studies.