Monte Carlo simulation for human health risk assessment of groundwater contaminated with arsenic at an Iranian semi-arid region

Abstract

The present study investigated the contamination of drinking water with arsenic and its human health risk assessment in Qorveh County, Kurdistan Province, Iran. The data of this study were collected and analyzed in the wet and dry seasons and from a total of 56 groundwater samples. This study used two deterministic and stochastic approaches to evaluate carcinogenic and non-carcinogenic risk. Monte Carlo simulation, which is based on the Markov chain approach, was used for risk assessment. The examination of heavy metals As, B, Cd, Cu, Hg, Mn, Ni, Pb, Sb, V, and Zn in the water samples reveals that except for the arsenic, the insignificant concentration of the abovementioned metals was found, consequently, the health risk studies were conducted focusing on the arsenic contamination. Data analysis revealed the average concentration of arsenic in the dry and wet seasons to be 14.93 ± 17.67 and 13.79 ± 16.57 μg/L, respectively. Furthermore, beyond 39 % and 35 % of the area of Qorveh County rely on groundwater sources having the arsenic contents more than the permissible level (10 µg/L) in dry and wet seasons, respectively. The Monte Carlo simulation output clearly showed that the HQ values ​​for the 95th percentile in the dry season were 3.58 and 2.03 for the age groups of children and adults, respectively. In other words, the non-carcinogenic risk for children is almost twice that of adults. All carcinogenic risk values was reported more than the acceptable threshold, typically set at 1 × 10⁻⁶ (or 1 in a million) by EPA. The sensitivity analysis of the contribution of arsenic concentration, duration of exposure, and rate of ingestion showed 89.5 %, 5.7 %, and 4.6 %, respectively, which indicates the major effect of arsenic concentration. The findings of this study provide an environmental alert to inform policy and attract appropriate financial resources for the management of drinking water sources containing arsenic in these areas.