INCIDENCE OF MALIGNANT NEOPLASMS AMONG RESIDENTS OF SMALL RADIONUCLIDE-CONTAMINATED CHORNOBYL DISTRICTS IN A POST-ACCIDENT PERIOD
Authors:   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine, Prysyazhnyuk A. , Fuzik M. ,   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine, Gudzenko N. ,   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine, Bazyka D. ,   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine, Fedorenko Z. ,   National Cancer Institute, 33/43 Lomonosova St., Kyiv, 03022, Ukraine, Ryzhov A. ,   National Cancer Institute, 33/43 Lomonosova St., Kyiv, 03022, Ukraine,   Taras Shevchenko National University of Kyiv, 60 Volodymyrska St., Kyiv, 01033, Ukraine, Soumkina O. ,   National Cancer Institute, 33/43 Lomonosova St., Kyiv, 03022, Ukraine, Trotsyuk N. ,   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine, Khukhrianska O. ,   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine, Danevych S. ,   State Institution «National Research Center for Radiation Medicine of the National Academy of Medical   Sciences of Ukraine», 53 Yuriia Illienka St., Kyiv, 04050, Ukraine
Published: December 2020

Objective. To assess the level of risks of development of malignant neoplasms among the residents of small Chornobyl districts («rayons») in connection with low-dose radiation exposure and its dynamic changes. Materials and methods. The study population included residents of Borodianka, Ivankiv and Poliske districts of Kyiv region («oblast») and Luhyny, Narodychi and Ovruch districts of Zhytomyr region, 175,100 inhabitants in 2017. The study period was 1980–2017. All cancers incidence rates as well as rates of potentially radiation-associated sites (breast, thyroid, hematopoietic and lymphoid systems) were calculated and analysed. Methods of variation statistics, descriptive and analytical epidemiology were used. Results. The impact of ionizing radiation on population of the most radionuclide-contaminated districts raises concerns of the potential threat of adverse cancer effects, especially thyroid cancer. The average total whole-body effective radiation doses received due to cesium during long time (1986–2005) among residents of the study districts (7.6–45.8 mSv) exceeded that in Zhytomyr (5.9 mSv), Kyiv (4.9 mSv) regions and Ukraine as a whole (2.48 mSv), but also in other districts in the North Ukraine. The average doses of internal radiation absorbed by the thyroid gland (161–1559 mGy) among the most vulnerable population – children and adolescents (aged 0–18 years at the time of the accident) of these areas, and obtained in the short post-accident period, significantly exceed that in Zhytomyr (87 mGy), Kyiv (81 mGy) regions and Ukraine as a whole (19 mGy). Irradiation rates of adult residents of these territories were lower, but significantly exceeded the average doses received by the population of Ukraine and large administrative units. Overall cancer incidence in the 6 districts during pre- and post-accident periods was lower comparing to Ukraine’s and Kyiv region’s rates, and did not significantly differ from Zhytomyr region’s rates. At the same time, the incidence rates of thyroid cancer significantly exceeded that of the pre-accident period as well as Zhytomyr region’s rates. Conclusions. The results of the study indicate needs for further monitoring of malignant neoplasms not only in the population of Ukraine as a whole and its large administrative-territorial units, but also among residents of particular areas, given the likelihood of the realization of the risks of radiation-associated diseases in the distant post-accident period in accordance with local environmental conditions. Key words: Chornobyl NPP accident, radiation exposure, malignant neoplasms, residents of the radionuclide-contaminated districts.