Health Risk Assessment in Children by Arsenic and Mercury Pollution of Groundwater in a Mining Area in Sonora, Mexico

A highly acidic spill from one of the most important copper mines in the Americas (Buenavista del Cobre) occurred in Sonora, Mexico in August, 2014. 40,000 m3 of metals-enriched sulphate solution escaped into the Sonora River representing the worst ecological disaster in Mexican history. The spill affected the economy, water accessibility and the health of residents near the river. Despite the economic importance of mining in this area, no environmental assessment was undertaken. There is no information about the health impact of this event on the local population. The study assesses the health risk among children exposed to arsenic and mercury via groundwater in five communities located in a mining area into the Sonora River Basin, Mexico. Local drinking water from the localities was sampled one year after the spill and it was analyzed for arsenic and mercury by Atomic Absorption Spectrometry coupled with Hydride Generation (AAS/HG). Further, some of the traditional local foods were sampled and analyzed for the same elements. Results indicate that levels of arsenic in drinking water did not exceed the Mexican Norm (25 μg As/L) or the EPA Guideline (10 μg As/L). The concentrations of mercury exceeded the WHO and Mexican Legislation value (1.0 μg Hg/L). The Hazard Quotient (HQ) values for arsenic were >1 in 42% of children exposed and for mercury in 67% of the children. Foods concentrations contained in the ranges of 9.2 to 62.0 μg As/Kg and 0.28 to 42 μg Hg/Kg for arsenic and mercury respectively. These values are below the Codex Alimentarius limits. Children affected by mining activities are at risk of developing chronic diseases associated with low arsenic and mercury exposure via groundwater consumption, without consideration of the contribution from these metals by other important exposures routes.