Relationship Between Iodine аnd Selenium Deficiency in Soil аnd Incidence of Thyroid Diseases in Population of Central Federal District

BACKGROUND: In recent decades, there has been an increased incidence of thyroid diseases worldwide. Following the Chernobyl accident, unique environmental and geochemical conditions developed in the Central Federal District, where the thyroid gland was affected by both environmental (microelemental deficiency, primarily iodine and selenium) and man-made (radioisotope contamination) factors. The studies have confirmed the relationship between iodine deficiency in the soil cover of the Central Federal District and the prevalence of thyroid diseases, including cancer. The study provides reliable data to prevent the diseases and to raise diagnostic alerts for the regional healthcare system and allows to develop the appropriate content for the population. AIM: To analyze regional differences of thyroid disease incidence in the population of the Central Federal District based on its microelemental status. METHODS: To analyze the population health of the Central Federal District and its constituent entities, we used population data, anonymized data on the number of patients with newly diagnosed thyroid diseases for 2013–2017, and incidence of malignant thyroid neoplasms for 1995–2023. To build a distribution model of microelements in the soil cover of the regions, the Unified State Register of Soil Resources was used. Each soil type–parent rock pair was assigned average content attributes. The reliability of microelemental estimates has been confirmed by field studies. We mapped iodine and selenium status of soils in the studied region. A nonparametric comparison of morbidity rates and map-based estimates was performed using the Spearman’s rank correlation. RESULTS: An analysis of soil samples collected in 2007–2023 in some regions of the Central Federal District confirmed the correctness of the map-based model of the estimated microelemental composition of soil. We found significant negative correlations (R=-0.473; p=0.055) between the iodine levels in the soils of the Central Federal District and thyroid diseases. For the adult population, we found a positive correlation between radioisotope soil contamination and the incidence of thyroid cancer (R=0.711; p=0.001). In addition, for children (0–17 years), we found a negative correlation (R=-0.375; p=0.138) between the iodine level in soils and the incidence of thyroid cancer. As the selenium level in the soils of the Central Federal District is within the reference range, no relationship was found between the incidence and this microelement level in the soil (R=-0.091; p=0.729). CONCLUSION: Comparison of geochemical and medical data in the context of spatial heterogeneity of risks associated with the effects of Chernobyl radioactive contamination of soil and natural deficiency confirmed the relationship between iodine deficiency in the environment and health status. There is a need to increase awareness of the population of the Central Federal District and heads of regional executive authorities of the adverse effects of micronutrient deficiency.