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Background@#Mongolia is characterized by restricted sources of drinking water and intensive water pollution due to high rates of urbanization, mining industry development, enormous amount of livestock, and ever-growing attempts in domestic production of cereals and vegetables. Among others, Se is the least studied element in Mongolian water resources. @*Goal@#To assess the selenium content of Mongolia’s drinking water depending on its geographical location and to identify areas of environmental risk associated with the chemical composition of the water.@*Materials and Methods@#In the summer of 2017, water samples were collected from 5 aimags (Dornogovi, Tuv, Selenge, Umnugovi, Arkhangai) and Ulaanbaatar city and sent to Moscow, Russia for analysis. Of the collected samples, 19 were groundwater (wells, wells, springs) and 2 were surface water (Tuul River, Selenge River).@*Results@#Based on fluorimetric method of analysis, the first results on Se levels in drinking water of five aimags, Ulaanbaatar, and Erdenet were obtained. Uneven distribution of Se in Mongolia was manifested, the highest Se concentrations being typical for the southern resources (up to 18,600 μg/L) and the lowest, for the Northern ones (up to 0.022 μg/L). ICP-MS data of Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, Hg, I, K, Li, Mg, Mn, Na, Ni, P, Pb, Si, Sn, Sr, V, and Zn contents indicate poly-microelementosis existence in the South of Mongolia (Dorno-Gobi aimag) where ground water is characterized by elevated levels of As and extremely high levels of Se, Li, Na, F, Cl, B, and nitrates ions, exceeding maximum permissible levels by 1.86; 4.3; 3.1; 3.1; 2.7; 3.4; and 1.8 times respectively. Toxic concentrations of Se in groundwater of Dorno-Gobi aimag contradict with the published low human serum Se and low content of the element in horseflesh that suggests the possible effect of the above pollutants on Se bioavailability. @*Conclusion@#Revealed phenomenon and mosaic distribution of heavy metals in areas with high and low Se content in water resources indicate the need of direct search for Se and other pollutant transfer in food chain in various ecological loading conditions, creation of a map of Se distribution in water resources of other Mongolian regions, and large-scale evaluation of the human poly-elemental status.
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@#Live species with selenium deficiency are unable to produce adequate antioxidant selenoprotein to defend themselves, so the virus may turn harmful and cause additional stubborn illness. </br> The disease associated with selenium deficiency in humans became known as cardiomyopathy or Keshan disease, an area in northeastern China that endemic spread. Some of the study results on the treatment of COVID-19 patients and selenium levels in patients are similar to previous studies indicating the antiviral effects of selenium. Indeed, various cellular and viral mechanisms, including selenium and selenoprotein, affect viral pathogens, including glutathione peroxidase, which depends on selenium encoded by the virus. Such viral mechanisms affect well-operated oxidative stress associated with multiple RNA-virus infections and increase viral replication (resulting in increased mutation frequency); as with SARS-CoV-2, selenium deficiency pathogens or mortality are high.</br> Inadequate selenium deficiency has been reported in the Mongolian population. According to a 2005 year study report by the University of Otto in New Zealand and the Center for Nutrition, 57% of children aged 06–35 months in Ulaanbaatar and four aimags had low selenium consumption in plasma. In most countries, the most important sources of selenium are meat and wheat products, and the concentration of selenium in the main staples eaten by Mongolians, such as wheat and meat, was remarkably low