Health status of children exposed in utero at various periods after the Chernobyl NPP accident, residing in territories subjected to radionuclide contamination, and methods of reducing the adverse consequences of radiation exposure

This study is devoted to the assessment of the health status of children exposed to ionizing radiation in utero at various periods after the Chernobyl NPP accident and residing in territories contaminated with radionuclides. The work considers children born between 26 April 1986 and 7 February 1987, as well as children born at later periods whose parents resided for an extended time in contaminated zones, including being of adolescent age at the time of the accident.

During the study, indicators of physical and intellectual development, the structure of congenital malformations and genetically determined diseases, genomic DNA repair capacity, the frequency of chromosomal aberrations in peripheral blood lymphocytes, and the state of the lipid peroxidation-antioxidant defense system are analyzed. On the basis of the data obtained, a complex of measures is substantiated, aimed at reducing the long-term consequences of radiation exposure in affected children.

Relevance of the problem.

Monitoring of the demographic-epidemiological situation in regions subjected to radionuclide exposure as a result of the Chernobyl accident made it possible to identify the negative influence of radiation on the health of the child population.

Particular attention is warranted for children who were exposed to radiation at various periods after the accident, including during the prenatal period. The child organism is characterized by enhanced cell proliferation and differentiation. Accordingly, the most pronounced changes are observed in the early postnatal period, when the organism has not yet formed mature regulatory and adaptive mechanisms. The danger of radiation exposure lies not only in the possible impact on the health of the child but also on their offspring in the form of genetic consequences (Baleva I.S. et al., 2001).

According to the Recommendations of the International Commission on Radiological Protection (ICRP, 1994), the main effects of external irradiation of the embryo and fetus are: embryonic death; developmental malformations; intellectual disability; heritable effects (chromosomal and gene mutations); and malignant neoplasms.

According to studies conducted after the Chernobyl accident, a dependence was identified between the health status of children and the duration of the radiation exposure period of the maternal organism. Thus, among women whose pregnancy occurred three months after the accident, the greatest number of premature and low-birth-weight children was observed compared with women whose pregnancy occurred before the Chernobyl NPP accident (Zasimova I.V., 1993).

From our perspective, it is important to analyze the consequences of ionizing radiation exposure on children at more remote periods. Children exposed in utero are those born between 26 April 1986 and 7 February 1987. Children born at later periods after the accident and residing in territories subjected to radionuclide exposure are, in essence, also exposed in utero, especially since their parents also resided in these territories for an extended period prior to the birth of their children, and some of them were of adolescent age at the time of the Chernobyl accident.

However, the available literature data on the effects of radiation on gametes, the fetus, and the developing child organism in the pre- and postnatal periods are contradictory. This is explained, on the one hand, by the impossibility of mechanical extrapolation of experimental research results to the human organism, and on the other hand, by the presence of both direct and indirect radiation effects, which invariably creates difficulties in interpreting their origins.

In this connection, there arises a need to study the long-term medical consequences of radiation exposure. This became the basis for our research and determined its goal.

Goal of the research. Based on long-term observation of children exposed in utero at various periods after the Chernobyl NPP accident and residing in a radioactively contaminated territory, identify impairments in their health status and substantiate a comprehensive set of measures aimed at reducing the long-term consequences of radionuclide exposure.

In accordance with the stated goal, the following tasks were carried out:

1. To assess the health status of children exposed in utero at various periods after the Chernobyl NPP accident and residing in a radioactively contaminated territory, and to determine their level of physical and intellectual development.

2. To determine the structure of congenital malformations, hereditary diseases, and minor developmental anomalies in children exposed in utero at various periods after the Chernobyl NPP accident and residing in a radioactively contaminated territory.

3. To conduct a comparative analysis of the state of genomic DNA repair capacity, the frequency and nature of chromosomal aberrations in peripheral blood lymphocytes of children exposed to radiation in utero at various periods after the Chernobyl NPP accident.

4. To assess the indicators of the lipid peroxidation-antioxidant defense system in children exposed to radiation in utero at various periods after the Chernobyl NPP accident and to establish their correlational relationship with the level of chromosomal aberrations and genomic DNA repair capacity.

5. To substantiate the advisability of implementing a complex of medical measures aimed at reducing the long-term consequences of radiation exposure in children.

Scientific novelty. Based on dynamic observation, features were identified in the structure of diseases among children exposed in utero at various periods after the Chernobyl NPP accident. In children born in 1986–1987, an increased proportion of diseases of the nervous and endocrine systems and congenital malformations was established. In children born in 1990, a predominance of endocrine diseases was found. In children born to adolescent parents at the time of the Chernobyl accident, an increased proportion of mental disorders and genetically determined diseases was identified. Changes were also revealed in the structure of congenital anomalies with a predominance of skeletal system malformations, which may indicate an adverse influence of ionizing radiation.

In children whose parents were of adolescent age at the time of the Chernobyl accident, monogenic, dominantly inherited diseases arising as a result of de novo mutations were diagnosed.

In all children exposed in utero at various periods after the Chernobyl NPP accident and residing in radioactively contaminated territories, an impairment of genomic DNA repair capacity to gamma radiation was established, which is accompanied by the appearance of chromosomal aberrations in peripheral blood lymphocytes of the examined subjects. In the group of children born in 1986–1987, the greatest number of children with chromatid and chromosomal aberrations was identified. A relationship was proven between the identified chromosomal abnormalities, reduced genomic DNA repair capacity, and insufficient lipid peroxidation-antioxidant defense processes in the observation groups.

Practical significance. A complex of measures was proposed aimed at reducing the identified negative consequences arising as a result of the Chernobyl NPP accident in children exposed in utero at various periods after the accident, including prenatal diagnostics, medical-genetic counseling, timely correction of congenital malformations, and a system of dispensary observation.

Implementation in practice. The results of the work have been implemented in the practical activities of the radiation risk clinic of the Moscow Research Institute of Pediatrics and Pediatric Surgery of the Ministry of Health of the Russian Federation and the children's polyclinic of Novozybkov, Bryansk Oblast.

Presentation of the work. The presentation of the work took place at a joint methodological meeting of the Department of Radiation Eco-Pathology and the Department of Hereditary and Congenital Diseases of Children with Mental Disorders of the Moscow Research Institute of Pediatrics and Pediatric Surgery of the Ministry of Health of the Russian Federation.