Trace elements human health risk assessment by Monte Carlo probabilistic method in drinking water of Shiraz, Iran

Risk assessment analysis related to groundwater contamination by heavy metals was performed in the Shiraz city (Iran). We compared the traditional deterministic methodologies with a probabilistic approach based on the concentration of different heavy metals determined from many sampling points. The relationships between the variables by the multivariate statistical analysis were assessed, and the target hazard quotient (THQ) was calculated in children, women, and men groups. Results showed that analyzed water samples were suitable for drinking, although alkaline. Concentrations of the heavy metals were: Zn > Ni > Cu > Se > Co > Sb. The THQ values for non-carcinogenic elements showed no significant risk for population of studied age groups, although a higher THQ value was observed for the water from the northwest and some central areas of city. Mean values of cancer risk for Ni were 1.77 × 10–5, 4.36 × 10–5, and 3.32 × 10–5 in children, women, and men, respectively. The multivariate approach indicated that the carcinogenic risk certainty level was 97.6, 91.2, and 94.3% for children, women, and men, respectively, and the model sensitivity analysis showed that the most effective parameter for carcinogenicity was Ni concentration. The probabilistic analysis also showed the relative influence of geogenic and anthropogenic processes on the quality of the water of Shiraz city. We concluded that risk assessment using a probabilistic approach could be better predictive of chronic exposure to hazardous elements in drinking water, which possibility the implementation of better protective measures than the current deterministic approaches.