CHARACTERISTIC FEATURES OF TOXIC METAL CONTENT IN HAIR SAMPLES OF FOREIGN STUDENTS AT RUDN UNIVERSITY FROM DIFFERENT GEOGRAPHIC REGIONS Article Kirichuk A.A., Skalny A.V., Chizhov A.Y., Tskhovrebov A.G., Schaumlöffel Dirk, Kritchenkov A.S. Journal of Trace Elements in Medicine and Biology. Elsevier GmbH. Vol. 80. 2023. 127303 p.