“…Hyperselenosis most often develops in individuals living in areas with a pronounced lack of selenium in soil, water, and food (Natasha et al, 2018). Biogeochemical regions with a lack of selenium are often found in the Non-Black Earth region stretching from the northeastern borders of the USA across the whole of Europe -the north of Germany, Holland, Denmark, Poland, through the Baltic countries, and Central Russia -to the Urals, then across Siberia to the eastern borders of Russia (Burtseva, 2012;Fordyce, 2013;Erdenetsogt et al, 2014;Stoffaneller and Morse, 2015;Zhang et al, 2018). Natural geochemical features of the territories, being a constant influence on the human body, can cause the development of endemic diseases.…”