Hg Pollution in Groundwater of Andean Region of Ecuador and Human Health Risk Assessment

In Ecuador, illegal gold mining has led to significant environmental impacts, with the release of harmful elements such as mercury (Hg) into the environment. Mercury, due to its physical–chemical characteristics and the transport elements involved between different environmental matrices, can easily percolate through the soil and reach groundwater. The purpose of this study was to evaluate the mercury concentration levels in the Andean region in order to perform a human health risk assessment. For this purpose, 175 water samples were analyzed, of which 9.71% exceeded the maximum permissible limit (MPL) established for drinking water in accordance with Ecuadorian regulations. The risk analysis was conducted by applying two approaches: deterministic and probabilistic. The deterministic approach involves a specific analysis based on the calculation of the risk quotient (HQ) and risk index (HI) for both receptors (adults and children) and scenarios (residential and recreational) considered; the probabilistic approach is based on the use of stochastic simulation techniques. The results obtained from the two approaches show a discrepancy, with the deterministic analysis providing more conservative results; however, they coincide in showing higher risk for the child population; decision-makers could use these results to identify areas to be monitored and plan more detailed investigation plans.