LEVELS AND RELATIVE RISKS OF MORTALITY OF CHORNOBYL CLEAN-UP WORKERS IN 1986–1987 YEARS FROM MAIN NON-NEOPLASTIC DISEASES (OBSERVATION PERIOD 1988–2021)
Authors:   State Institution «National Research Center for Radiation Medicine, Hematology and Oncology of the National Academy of Medical Sciences of Ukraine», Fedirko P. A. , Babenko T. F. ,   State Institution «National Research Center for Radiation Medicine, Hematology and Oncology of the National Academy of Medical Sciences of Ukraine», Kapustinska O. A. ,   State Institution «National Research Center for Radiation Medicine, Hematology and Oncology of the National Academy of Medical Sciences of Ukraine», Belyaev Y. M. ,   State Institution «National Research Center for Radiation Medicine, Hematology and Oncology of the National Academy of Medical Sciences of Ukraine», Tereshchenko S. O. ,   State Institution «Ukrainian Center of Information Technologies and National Register of the Ministry of Health of Ukraine», Dorichevska R. Y. ,   State Institution «National Research Center for Radiation Medicine, Hematology and Oncology of the National Academy of Medical Sciences of Ukraine»
Published: December 2024

The emergency destruction of the 4th reactor of the Chornobyl nuclear power plant necessitated large-scale emergency work, which involved large contingents of specialists. Analysis the mortality of Chornobyl clean-up workers is an important and relevant basis for planning medical protection measures in conditions of a potential threat of emergency and other radiation situations.
The objective of this work is to determine the levels and relative risks of mortality of Chornobyl clean-up workers in 1986–1987 years from major non-tumor diseases depending on the received dose of radiation exposure, taking into account age and time after the accident (period of epidemiological studies 1988–2021).
Materials and methods. The cohort of Chornobyl clean-up workers in 1986–1987 years with a known dose of external γ-irradiation of the whole body, totaling 64,490 male, was divided by age at the date of the accident at the Chornobyl nuclear power plant and dose of external γ-irradiation of the whole body. Epidemiological analysis of mortality from non-tumor diseases was conducted for the entire post-accident period and in dynamics over five-year monitoring periods.
Results. The highest mortality rate, regardless of age, on the date of the Chornobyl disaster, were from diseases of the circulatory system, of the digestive and respiratory systems. For Chornobyl clean-up workers 18–39 years on the date of the accident, relative risks of mortality from non-tumor diseases over the entire observation period were significantly higher in all dose subgroups (from 0.05 Gy to 0.7 Gy) compared to the dose subgroup < 0.05 Gy. In the period 1993–1997 (6–10 years after the Chornobyl accident), significantly higher relative risks of mortality from diseases of the circulatory system (pulmonary heart and pulmonary circulatory disorders, cardiomyopathy, myocardial infarction) were found; in 26–30 years – from cerebrovascular diseases, including cerebral infarction. The indicated reliable dose-dependent relative risks are characteristic of all dose subgroups relative to the subgroup with a dose < 0.05 Gy.
Conclusions. The overall mortality of Chornobyl clean-up workers from non-tumor diseases tends to increase. The results of the risk analysis of dose dependent mortality in the Chornobyl clean-up workers cohort showed a higher sensitivity to ionizing radiation of persons of the younger age group (18–39 years old at the date of the accident). The most dangerous period of relative dose-dependent risk of death of Chornobyl clean-up workers due to non-tumor diseases was established – 6–10 years after radiation exposure for all dose subgroups (from 0.05 Gy to 0.7 Gy) relative to the subgroup with a radiation dose < 0.05 Gy.
Key words: Chornobyl NPP; ionizing radiation; mortality; non-tumor diseases; radiation exposure; clean-up workers; relative risks.