Heavy metals and arsenic in drinking water and health risk assessment of the region with the developed mining industry

Abstract

Introduction. Drinking water intended for South Armenia’s towns and rural communities is abstracted from minor mountain rivers belonging to the basins of the Voghchi and Meghri, the water of which is treated at five water treatment plants. The river basins are home to the major copper molybdenum and gold ore mining centers of the republic.The purpose of this research was to study heavy metals Ag, Al, As, Cd, Cu, Fe, Mo, Ni, Pb, Sn, Sb, Se, Zn, Hg, Te in centralized drinking water supply systems and assess drinking water-caused health risks to the population.Material and methods. In 2016-2017 from 43 sampling sites a total of 53 basic water samples were taken, including 14- from surface water supply sources, 16 - from water treatment plants, 33- from water supply networks. Heavy metals were determined by the atomic absorption method. To assess the quality of water on water abstraction sites relevant ecological (regional) norms and national and international standards were used. The risk of development of noncarcinogenic and carcinogenic effects was assessed in the case of oral intake of and dermal exposure to tap water.Results. On water abstraction sites, background regional levels of surface waters exceeded the concentration of aluminum, iron, molybdenum, tin, antimony (by as 13.3-1.1 times). Water treatment efficiency at water treatment plants is estimated at 12% - 69% depending on different metals. Concentrations of heavy metals in drinking water do not exceed the norms. The risk of development of noncarcinogenic effects in the population at chronic exposure to drinking water is insignificant (HI<1), whereas a total carcinogenic risk exceeds a safety limit for arsenic (CR=9.59×10–5).Conclusion. The acceptable quality of drinking water supplied to consumers is not yet an index of sustainable and safe water supply in the studied region because of a water pollution level on intake sites, obsolete water treatment technologies, poor sanitation and technical condition of plants and water networks.