Comprehensive Probabilistic Health Risk Assessment for Exposure to Arsenic and Cadmium in Groundwater

Probabilistic health risk assessment has widely been used for more realistic risk analysis of contaminants. However, the existing probabilistic modeling process may be unable to reflect the actual health risks comprehensively. In the present study, the Monte Carlo simulation was employed to assess the probabilistic health risks of exposing to arsenic (As) and cadmium (Cd) in groundwater through ingestion and dermal contact pathways. To systematically evaluate the actual health risks of residents, two scenarios of the probabilistic health risk assessment were proposed: (1) fixed exposure parameters, whereas uncertain metal concentrations, and (2) uncertain exposure parameters and metal concentrations. The results indicated that the mean hazard index (HI) for local residents was mostly accepted (HI < 1), while the non-cancer risk of infants at the 95th percentile under scenario 2 (HI = 1.42) exceeded the safe level of 1, signifying the potential non-cancer risk on infants. Meanwhile, the average total cancer risk (TCR) values were several times greater than the acceptable limit of 1E-06 for all the age groups under both scenarios 1 and 2, reflecting the unacceptable cancer risk. Moreover, sensitivity analysis identified the exposure duration (ED) and concentration factor (C_W) were the most relevant parameters that affect the health risk. Overall, the results of this study will be useful for the policy makers in comprehensively understanding the actual health risks of the heavy metal(loids) contamination in groundwater on receptors, as well as setting up suitable groundwater management strategies to guarantee safe water supply and to maintain health for local residents.