Health risk assessment of toxic elements in Kashan drinking water reservoirs using Monte Carlo simulation and sensitivity analysis

In today's world, given the industrialization of societies and the water scarcity crisis, the issue of water resource protection has gained attention. Among water pollutants, toxic elements are among the most significant. Therefore, this study was conducted with the aim of assessing the health risk posed by exposure to toxic elements in the drinking water of Kashan, Iran. In this study, 39 water samples were collected from 13 active water reservoirs. The concentrations of toxic elements including arsenic (As), lead (Pb), and cadmium (Cd) were determined using ICP-MS and compared with national and international standards. Ultimately, human health risk assessment was calculated using the United States Environmental Protection Agency (USEPA) index, carcinogenic and non-carcinogenic risks were evaluated for three age groups-children, teenagers, and adults-using a Monte Carlo simulation-based method with the help of Crystal Ball (Oracle) software. The average concentrations of As, Pb, and Cd in the drinking water reservoirs of Kashan city were 3.94 µg/L, 0.86 µg/L and 0.35 µg/L, respectively. The hazard quotient (HQ) and hazard index (HI) for all age groups were below the safety limit (HQ < 1). The cumulative excess lifetime carcinogenic risk (ELCR) values for Pb and Cd were below the safety limit; however, for As, the ELCR values in children and teenagers were 1.73 × 10⁻⁴ and 1.59 × 10⁻⁴, respectively, exceeding the permissible limit. This indicates that these two age groups may be at risk in the long term. A sensitivity analysis was conducted and confirmed that there is a potential risk to the health of children. It is recommended that continuous monitoring and risk management be implemented to protect public health, particularly for the age group of children and teenagers. Also, more comprehensive studies in different seasons of the year are recommended.