Investigating the concentration of heavy metals and their health risk assessment in the water resources of northwestern Iran

The presence of heavy metals in water sources is a serious threat to the health of consumers in terms of the possibility of various diseases related to the consumption of contaminated water. Therefore, this study was conducted with the aim of investigating the concentration of heavy metals and assessing their health risk in water resources of Ardabil province. In this cross-sectional descriptive study, 150 samples were prepared from different water sources of Ardabil province in 2021 and 2022 years and were analyzed by ICP-MS according to the standard methods. In the present study, composite sampling method was used. The average concentrations of Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Hg and Pb were compared with three standards (National Standard 1053 of Iran, WHO and USEPA). Also, health risk assessment was done for two age groups of children and adults based on USEPA criteria. The results showed that the highest and lowest average concentrations of metals in the locations of springs, wells, inlets and outlets of water treatment plants and distribution networks are respectively for arsenic and copper metals, and in rivers, it is related to iron and zinc. Considering the percentage of metal concentrations compared to their standards, in general, the highest and lowest average concentrations of metals in underground, surface water sources and distribution networks in the whole province of Ardabil were related to arsenic and copper metals, respectively. Also, in autumn, winter and summer, the highest concentration of metals was related to arsenic and the lowest was related to copper. The total non-carcinogenic risk for children was 2.36, and it was 1.011 for adults, and the total carcinogenic risk in underground, surface water sources and distribution networks were more than 10^–4. The amount of contamination of water sources in the northern rivers of Ardabil province with the As, Pb, Hg, Mn and Fe was higher than the amount of national and international standards. However, in the rivers of the central and western regions of this province, only the concentration of arsenic was higher than the standards. Among the springs of the entire province, the concentration of heavy metals in the springs of the east and southwest regions were within the standard range, but the concentration of arsenic in them was more than the standard. The possibility of noncancerous diseases in both the adult and children age groups of the study population is high, and the risk of diseases in children is higher than in adults. The probability of carcinogenicity of water consumption with the monitored concentration of arsenic metal in the studied area has a high risk. According to the average of all monitored metal concentrations, there is a possibility of carcinogenicity in different degrees in all water sources. Therefore, conducting continuous monitoring studies to determine the incidence and prevalence of diseases related to these metals, especially arsenic, seems to be critical.