Burdo O. The assessment of mouse-like rodents state form ChNPP exclusion zone in the remote post-accident period by a set of biological indicators

The thesis is devoted to the research of the state of model species of murine rodents in the remote post-accident period with hematological and cytogenetic parameters in the long-term period after the Chernobyl accident, taking into account radiation factors. A radioecological study of 6 research sites of the Chornobyl NPP (dose rate of external γ-irradiation, radionuclide contamination density) located at a distance of 3– 25 km from the emergency unit was carried out. The content of the main doseforming radionuclides (137Cs and 90Sr) in the body of animals was determined. During 2008–2016, dynamic changes in the levels of radionuclide accumulation in the bodies of red-backed voles were observed, showing that this has occured due to changes in the bioavailability of individual radionuclides in the ecosystem under the influence of climatic factors and succession processes. The study of the blood system of bank vole from the test sites in the Chornobyl exclusion zone revealed the features of radiogenic changes, manifested, on the one hand, in the suppression of erythroid and myeloid hematopoietic series with a corresponding decrease in erythrocytes and neutrophilic and eosinophilic granulocytes in peripheral blood, and on the other hand, an increase in thymus mass and the number of peripheral blood lymphocytes. It is shown that in the blood system of animals under the chronic exposure to small doses of ionizing radiation on the background of pathological and destructive changes the compensatory-restorative processes take place. As the evidence of this, the formation of extramedullary foci of hematopoiesis in the spleen, as well as hyperplastic processes in the thymus can be observed. The detected instability and fluctuation of critical body systems under the influence of chronic irradiation indicate a significant modifying effect of natural and climatic stressors on the formation of compensatory-conforming and adaptive processes in natural populations of murine rodents which inhabit the contaminated areas of the Chernobyl exclusion zone.