Introduction. A preliminary epidemiological analysis of the development of cardiac pathology in individuals evacuated from the 30-kilometer zone of the Chornobyl NPP, aged 18-60 years, over a 30-year post-accident period (1992-2022), revealed high absolute risks of developing non-cancerous diseases of the circulatory system despite the absence of subsequent radiation exposure. The subjects received gamma radiation doses ranging from 0.001 Sv to 0.38 Sv. These findings support the hypothesis of deterministic development of cardiac pathology due to low doses of radiation, indicating a cause-and-effect relationship between radiation exposure and the development of such diseases. Radiation exposure generates highly active toxic substances in low concentrations, known as radiotoxins (RTs), which can significantly enhance the direct effects of radiation and contribute to the development of pathology in the absence of ongoing radiation exposure. This article focuses on an epidemiological analysis and risk assessment of circulatory system diseases in adults aged 18-60 years who were evacuated from the 30-km zone of the Chornobyl nuclear power plant post-accident, to establish the causal relationship between radiation exposure and disease risk, and to assess the effects of different radiation dose ranges.
Objective: To epidemiologically assess the incidence of non-cancerous diseases of the circulatory system in individuals evacuated from the 30-kilometer zone of the Chornobyl nuclear power plant during the period 1992-2022, and to evaluate the dose-dependent medical effects of low doses of ionizing radiation.
Materials and Methods: An analytical analysis was conducted on the dose-dependent development of non-cancerous circulatory system diseases due to low doses of radiation exposure in the post-accident period. Cardiological examinations were performed on 3,757 evacuees from the 30-kilometer zone of the Chornobyl NPP, aged 18-60 years, with individual total effective doses of ionizing radiation ranging from 0.001 Sv to 0.38 Sv. To establish the dose-dependent development of these diseases as a long-term effect of low-dose radiation, the cohort was divided into two groups: the first exposed group (EG) consisting of 1,934 individuals with an average dose of 0.07 ± 0.003 Sv (ranging from 0.051 Sv to 0.38 Sv), and the second control group (CG) comprising 1,822 individuals with an average dose of 0.04 ± 0.002 Sv (ranging from 0.001 Sv to 0.05 Sv). To determine the "factor-risk" relationship, we used absolute risk (AR) with 95% confidence intervals (95% CI), attributable risk (ATR), and relative risk (RR) with 95% confidence intervals (95% CI). For dose range effects ("dose-effect"), we assessed the excesses of absolute (EAR) and relative risk (ERR) with 95% confidence intervals.
Results: Surveillance over the 30-year post-accident period (1992-2022) indicated a reliable dependence of cardiac pathology development on the radiation doses received during evacuation, specifically from 0.051 Sv to 0.38 Sv, which can be considered a significant risk factor. The ATR for circulatory system diseases was 34.07, with the RR significantly above 1.08 (1.05-1.10). For specific non-cancerous diseases, ATR ranged from 0.39 to 14.21 with relative risks of 1.79 (1.75-1.81) and 1.12 (1.09-1.15).
The EAR and ERR calculations confirmed the radiogenic risk of non-tumor cardiac pathology from doses ranging from 0.051 Sv to 0.38 Sv compared to lower doses (0.001 Sv to 0.05 Sv). In the category "Diseases of the circulatory system (I00-I99)", the ERR for EG subjects was 486.71 (474.92-498.84) with a significant ERR (95% CI) of 1.11 (1.08-1.14). For individual diseases, ERR ranged from 203.03 (198.11-209.09) to 5.63 (5.50-5.77), with reliable confirmation of ERR from 1.68 (1.64-1.73) to 11.33 (11.06-11.62).
Conclusions.
Keywords: evacuees, diseases of the circulatory system, developmental risks, radiotoxins.
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