Risks to Human Health from the Consumption of Water from Aquifers in Gold Mining Areas in the Coastal Region of Ecuador

Artisanal and Small-scale Gold Mining (ASGM) is a source of supply in many areas of the world, especially in developing countries. This is often carried out illegally using toxic substances such as mercury. Mercury, due to its chemical-physical properties and the transport factors involved between the different environmental matrices, can percolate through soil and from surface water to groundwater. The objective of this study was to conduct a human health risk assessment. For this purpose, a screening of mercury concentrations was carried out, collecting 67 water samples at selected points, and a risk assessment was performed applying both a deterministic and a probabilistic approach. A deterministic approach is a specific analysis based on determining the values of the risk quotient (HQ) and the risk index (HI) for each receptor category (adults and children) and scenario (residential and recreational) considered; a probabilistic approach is based on stochastic simulation techniques and the evaluation of the statistical quantities. There was found to be a discrepancy between the results provided by the two approaches, with the deterministic approach suggesting a more worrisome picture. However, in general, the results showed a greater exposure in the provinces of El Oro and Esmeraldas, and a greater vulnerability of child receptors.