Human health risk assessment of metals and metalloids in mining areas of the Northeast Andean foothills of the Ecuadorian Amazon

Abstract

Gold mining (GM) is a major source of metals and metalloids in rivers, causing severe environmental pollution andincreasing the exposure risks to the residents of surrounding areas. Mining in Ecuadorian Amazonia has dramatically in-creased in recent years, but its impacts on Indigenous local populations that make use of rivers are still unknown. The aim ofthis study was to assess the risks to adults and children caused by the exposure to metals and metalloids in freshwaterecosystems contaminated with tailings released by GM activities in 11 sites of the upper Napo River basin, Ecuador. Weselected a carcinogenic and a noncarcinogenic risk assessment method to estimate the hazard index (HI) and total cancerrisk (TCR). The concentration of Ag, Al, As, Cd, Cu, Fe, Mn, Pb, Zn, B, and V in water and sediment samples was considered toassess the risks to human health. The calculated HI was 23–352 times greater than the acceptable limits in all sites for bothchildren and adults. Mn and Fe were the main contributors (75% in water and 99% in sediment) to the total calculated riskbased on the HI. The calculated TCR for children and adults exceeded approximately one to three times the permissiblethreshold in all sites. As and Pb contributed up to 93% of the total calculated risk based on TCR for both children and adults.This study demonstrates that the emission and mobilization of metals and metalloids caused by mining activities increase therisk to human health, to which we recommend further monitoring of freshwater contamination in the area and the im-plementation of preventive health management measures