Bandazhevsky Yu. I., Dubovaya N. F.
Ecology and Health Coordination and Analytical Centre, Ukraine (Kyiv 2026)

Our research over many decades allows us to draw a number of important conclusions regarding the radiation impact on the human population following the accident at the Chornobyl nuclear power plant (ChNPP).

The Chornobyl accident resulted in the release of a huge amount of radioactive elements into the environment, predominantly ¹³⁷Cs. This radionuclide decays with the release of gamma and beta radiation, forming stable ¹³⁷Ba.

¹³⁷Cs entered and continues to enter the bodies of residents of the affected areas primarily through the enteral route with food of animal and plant origin.

In the USSR, as well as several independent states that emerged as a result of its dissolution, permissible levels of ¹³⁷Cs and ⁹⁰Sr in food products were established by law.

The rationale for creating these regulations was economic feasibility, based on the existence of agricultural products with certain levels of ¹³⁷Cs and ⁹⁰Sr in various years after the Chornobyl accident.

As the specific activity of these radionuclides in food products decreased, regulatory requirements were tightened.

However, this did not exclude the constant intake of radioactive elements into the human body.

Thus, the legislation permitted the enteral ingestion of significant quantities of ¹³⁷Cs and ⁹⁰Sr.

However, the impact of these radionuclides on the health of children and adults was not determined.

Radiation exposure of residents of the affected areas is facilitated by forest fires in the Chornobyl Exclusion Zone (ChEZ), as well as the use of wood containing radioactive elements.

For many decades, millions of people have lived and continue to live under conditions of constant radiation exposure.

In the first decade after the Chornobyl accident, ¹³⁷Cs intake by children and adults was significant, allowing us to determine the incorporation of this radionuclide into individual internal organs.

Contrary to previous belief, we have established that ¹³⁷Cs is intensively absorbed by the thyroid and pancreas, liver, kidneys, heart muscle, and even the brain [1] (slide 2).

To assess the impact of ¹³⁷Cs radionuclides on metabolic processes in the bodies of residents of the affected areas, we conducted numerous clinical, instrumental, pathological, and biochemical studies of children and adults, as well as experiments on laboratory animals.

These studies assessed structural and metabolic changes in vital organs at varying specific activity levels of ¹³⁷Cs in the body.

The simultaneous penetration of ¹³⁷Cs into the tissue of the heart, liver, kidneys, thyroid gland, and other internal organs caused damage to their cellular structures, resulting in the syndrome of incorporated long-lived radionuclides (SLIR) [2]. The underlying pathological processes are mitochondrial damage and disruption of cellular energetics.

At a specific activity of ¹³⁷Cs in the body of 30-50 Bq/kg, ultramicroscopic examination revealed an increase in mitochondrial size and fusion in myocardial cells, indicating not only damage but also the development of reparative processes [2] (slide 3).

Furthermore, significant structural changes occurred in myocardial tissue, which may be the cause of death [2] (slide 4).

During the studies conducted in Ukraine in 2013-2017 within the framework of the projects of the European Commission and the Regional Council of Rhone-Alpes (France), in a group of children living near the ChEZ, damage to the mitochondria of cardiomyocytes was detected in 37.5% of cases [3].

In these studies, mitochondrial damage in children's cardiomyocytes was assessed based on the activity of serum transaminases—aspartate aminotransferase (AST) and alanine aminotransferase (ALT).

The negative impact of incorporated ¹³⁷Cs radionuclides on the mitochondria of cardiomyocytes in the children studied is reflected by the direct relationship between ¹³⁷Cs specific activity and serum AST levels [3] (slide 5).

The inverse correlation between ¹³⁷Cs specific activity in the body and serum calcium concentration [4] (slide 6) reflects energy deficiency caused by impaired mitochondrial function, which contributes to the disruption of the ionic composition within the cells of the cardiac leading system and the development of arrhythmias

The reduction in the energetic capacity of cardiomyocytes due to the influence of incorporated ¹³⁷Cs radionuclides leads to a decrease in the contractility of the heart muscle, which leads to a decrease in blood pressure and a reduction in the blood supply to organs and systems [4] (slide 6). This results in impaired physical development of the child.

The negative impact of incorporated ¹³⁷Cs on anabolic processes in the developing child's body reflects the inverse correlation between the specific activity of this radionuclide in the body and the Rohrer index values [4] (slide 6).

In the first decade after the Chornobyl accident, a direct correlation was found between the frequency of electrocardiographic changes, predominantly represented by incomplete right bundle branch block, and the specific activity of ¹³⁷Cs in the body in a group of children living in the affected area [2, 5] (slide 7).

A similar correlation was found in the development of cataracts in children living in areas with ¹³⁷Cs soil contamination densities of 5-15 Ci/km² and 15-40 Ci/km² [2] (slide 8).

Heart rate disturbances were also detected in most children of the second generation of Chornobyl survivors living near the ChEZ [3] (slide 9).

However, the specific activity of ¹³⁷Cs in these children's bodies was significantly lower than in children examined in the first decade after the Chornobyl accident [6].

Mitochondrial dysfunction in children living near the ChEZ, which arose in the late post-Chornobyl period under the influence of incorporated ¹³⁷Cs, became one of the main causes of impaired adaptation processes and reduced cardiovascular reserve capacity.

Poor adaptation and failure of adaptation mechanisms were recorded in 50% of cases [7,8] (slide 10). Below-average cardiovascular functional reserve was detected in 40.3% of cases, and low levels were detected in 31.3% of cases [7,8] (slide 11).

Pathological changes in the kidneys cause metabolic disorders in the body.

The kidneys are the organs that eliminate ¹³⁷Cs from the body. The most pronounced pathological changes were found in the glomerular apparatus. The most common manifestation was progressive destruction of glomerular structures, leading to complete disappearance—the "melting ice floe" phenomenon [2] (slide 12).

The results of ultrasound examination indicate serious structural changes in the liver and metabolic disorders in 35.0% of children living near the ChEZ [3] (slide 13).

Studies have revealed a direct correlation between the specific activity of ¹³⁷Cs in the body and indicators reflecting vital functions in children [3] (slide 14).

Under conditions of energy deficiency associated with the incorporation of ¹³⁷Cs into the body, a large number of children developed hyperhomocysteinemia— elevated blood levels of the amino acid homocysteine.

Homocysteine is a sulfur-containing amino acid that is an intermediate in the metabolic cycles of the essential amino acid methionine, which is a source of methyl groups for the body [9] (slide 15).

Homocysteine levels in the blood reflect the efficiency of methylation of nucleic acids and protein molecules.

An increase in homocysteine concentrations in the blood indicates a disruption in its methylation and a decrease in the formation of endogenous methionine.

In adults, hyperhomocysteinemia is associated with a number of severe cardiovascular diseases, oncological processes, and pathologies of the central nervous system [3] (slide 16).

During the implementation of projects by the European Commission and the Rhône-Alps Regional Council in 2015, hyperhomocysteinemia was identified for the first time in a large number of children living near the ChEZ [3] (slide 17).

The highest number of cases of hyperhomocysteinemia was detected in the group of children carrying the T allele of the MTHFR:677 genetic polymorphism, due to its homozygous variant [3] (slide 18).

The increase in hyperhomocysteinemia cases in the study group of children following the forest fires in the ChEZ was not associated with the T allele of MTHFR:677 [3,10] (slides 19, 20, 21).

In most cases, elevated homocysteine levels in the children's blood were not associated with folate cycle genes, unlike in their mothers, whose blood homocysteine levels were dependent on the state of the genetic apparatus controlling the methylation process [3] (slides 22, 23, 24).

Comprehensive laboratory and genetic studies have established that the cause of hyperhomocysteinemia in children from areas affected by the Chornobyl accident is impaired mitochondrial function and reduced energy potential in the cells of vital organs.

After years of analytical research, it was concluded that hyperhomocysteinemia in children living near the Chornobyl accident is not only a manifestation of a pathological process associated with impaired secondary methionine formation, but is also an element of the adaptive system aimed at correcting metabolism under radiation exposure.

When homocysteine concentrations in the blood increase, a complex of reactions is activated aimed at eliminating the causes of oxidative stress and restoring mitochondria as energy sources.

This activates the transsulfuration reaction cycle, which utilizes homocysteine to form cysteine and glutathione, an important component of the antioxidant system [6].

This process is most pronounced in children living near the ChEZ, with a disruption in the functioning of B12 methionine synthase due to the polymorphic allele GMR:2756 in the genome [6].

Homocysteine stimulates the formation of triiodothyronine, the active form of thyroid hormone that can influence energy processes in the mitochondria [9] (slide 25), as well as the formation of cortisol, which has an antioxidant effect [6].

Furthermore, homocysteine promotes an increase in serum calcium concentrations, thereby maintaining ionic balance between the vascular system and tissues.

It is worth noting the subgroup of children carrying the T allele of the MTHFRM:677 genetic polymorphism. This subgroup demonstrated the strongest direct association between homocysteine and serum calcium [4] (slides 26, 27).

In the course of studies conducted in most genetic subgroups, a direct association was found between serum phosphorus and parathyroid hormone, indicating the body's ability to excrete phosphorus through the glomerular structures of the kidneys.

The absence of this association in the subgroups of children with the G alleles of MTR:2756 and T alleles of MTHFR:677 is a manifestation of a disorder of phosphorus metabolism.

Clinical observations and experiments with laboratory animals have revealed the teratogenic effect of ¹³⁷Cs radionuclides incorporated into the body.

Congenital malformations belonged to a group of multifactorial defects associated with genetic and environmental factors. They involved the brain and facial region of the skull [2,3,10] (slides 28, 29).

The effect of ¹³⁷Cs radionuclides on the fetus during pregnancy disrupts the development of nonspecific and specific resistance in the developing organism. At the same time, fetal blood cortisol levels decrease [2] (slide 30).

The information obtained during the implementation of projects of the European Commission and the Rhône-Alps Regional Council in Ukraine allows us to conclude that intrauterine developmental disorders induced by incorporated ¹³⁷Cs are associated with the process of methylation of nucleic acids and proteins.

These studies allow us to draw the following conclusion regarding the human population living in areas where soils are contaminated with radionuclides as a result of the Chornobyl accident.

In the first decade after the Chornobyl accident, adults and children develop oncological diseases of the thyroid gland and internal organs, cardiopathology, pathology of the central nervous system and internal organs associated with exposure to relatively large doses of short- and long-lived radionuclides.

A syndrome of incorporated long-lived radionuclides is characteristic.

During this period, antenatal and postnatal ontogenesis are disrupted, and congenital malformations of a multifactorial nature arise.

In the late period following the Chornobyl accident, adults develop cancer, cardiac pathologies, and pathologies of internal organs and the central nervous system.

Children of the second generation of Chornobyl survivors have been diagnosed with congenital structural and functional disorders of their internal organs, nervous system, and musculoskeletal system. Reduced adaptive capacity of children leads to cardiovascular, infectious, and oncological diseases, as well as decreased resistance to radiation, chemical, and physical agents.

Hyperhomocysteinemia in most children of the second generation of Chornobyl victims living near the ChEZ is a manifestation of a pathological process affecting vital organs.

We believe this is due to the effects of ¹³⁷Cs and other radionuclides on the maternal-fetal system, which alters the regulatory relationships between metabolic processes in vital organs in the developing organism. This results in a decrease in the production of antioxidant system components, including cortisol. This, upon incorporation of ¹³⁷Cs, leads to mitochondrial damage and, consequently, to disruption of homocysteine methylation and a decrease in the formation of endogenous methionine and adenosylmethionine, the main source of methyl groups.

However, in some cases, hyperhomocysteinemia is a component of the body's adaptive response to radiation exposure.

 

References:

1. Bandazhevsky Yu. I. Chronic Cs-137 incorporation in children's organs. Swiss Medical Weekly. 2003. Vol. 133. P. 488 - 490. https://doi.org/10.4414/smw.2003.10226

2. Badazhevsky Yu., Dubovaya N., Bandazhevskaya G., Kadun O., Perepletchikov A. Zherbo L., Chornobyl 25 years: incorporated radionuclides Cs-137 and human health. - Tokyo. - 2015. - 132 p. [Japanese]

3. Bandazhevsky Yu. I., Dubovaya N. F. Chornobyl catastrophe and childrens health. 35 years of world tragedy. Ivankov: PI Coordination and Analytical Center «Ecology and health», - Kyiv: «Alyant» LLC, 2022. 158 p. ISBN 978-617-7819-29-4

4. Bandazheuski Yu., Dubovaya N. Participation of homocysteine in the regulation of calcium-phosphorus metabolism and cardiovascular function in children living in areas affected by the Chornobyl Nuclear Power Plant accident // Modern science: theory, practice, innovative technologies : Scientific monograph. Part 1. Riga, Latvia : Baltija Publishing, 2025. P. 331-356. DOI: https://doi.org/10.30525/978-9934-26-602-7 (ISBN: 978-9934-26-602-7)

5. Bandajevsky Y. I., Bandajevskaya G. Cardiomyopathies on cesium 137. Cardinale. revue de cardiologie. 2003. Vol. 15. № 8. P. 40-42. (French).

6. Bandazheuski Yu., Dubovaya N. Folate cycle genes and adaptation processes in children living near the Chornobyl Exclusion Zone // Transformation of the scientific area in the context of contemporary challenges : Scientific monograph. Riga, Latvia : Baltija Publishing, 2025. P. 242-260. DOI: https://doi.org/10.30525/978-9934-26-631-7-10 (ISBN: 978-9934-26-631-7).

7. Dubovaya N., Bandazheuski Yu. Adaptation resources of the cardiovascular system of schoolchildren living near the Chornobyl nuclear power plant // Scientific space: integration of traditional and innovative processes: Scientific monograph. Riga, Latvia: Baltija Publishing, 2023. P. 147-170. DOI: https://doi.org/10.30525/978-9934-26-310-1-5

8. Дубова Н. Ф., Бандажевський Ю. І. Оцiнка адаптацiйних можливостей серцево-судинноi системы школярiв, якi мешкають поблизу Чорнобильськоi зони вiдчуження. Environment & Health.2023. № 2 (107). P.24-30. https://doi.org/10.32402/dovkil2023.02.024

9. Bandazhevsky Yu. I., Dubovaya N. F. Regulation of thyroid gland function in children living in areas affected by the Chornobyl nuclear power plant ассident. Ivankiv: PI Coordination and Analytical Center «Ecology and Health», — Kyiv, FOP Samchenko A. M., 2025. 80 р. ISBN 978-617-8413-19-4

10. Bandazhevsky Yu. I., Dubovaya N. F. Forest fires in the Chornobyl exclusion zone and children’s health. Ivankov : PI Coordination and Analytical Center «Ecology and health», - Kyiv : «Aliant» LLC. 2021. 44 p. ISBN978-617-7819-10-2

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