Risk assessment for the consumption of the freshwater turtle Podocnemis unifilis with Hg in an indigenous population living close to mining area in the brazilian Amazon

Podocnemis unifilis is an important source of protein for indigenous communities in the Brazilian Amazon. However, contaminants associated to the mining activities can be affecting this species and, in turn, its consumers. The objective of this study was to evaluate the risk of Hg contamination that the Kayapó indigenous people are exposed to through the consumption of P. unifilis in a region affected by mining in the Baú river basin, municipality of Altamira-PA, Brazilian Amazon. Muscle (edible) samples of the collected specimens were digested in a solution of concentrated nitric acid with hydrogen peroxide using a microwave digestion system. Inductively coupled plasma emission spectrometry with hydrogen generation was used to quantify HgT. The health risk assessment was performed according to the methodology proposed by the U.S. Environmental Protection Agency. The muscle of P. unifilis presented an average concentration of 0.022 (µg/g wet weight) HgT, a value within the allowed level for the dietary pattern. The risk assessment for human health shows that the consumption of P. unifilis presents low risks of intoxication by Hg for the indigenous people. The results show a reduced risk of exposure to Hg due to the consumption of P. unifilis by indigenous people. However, if mining activity continues to spread across the region, since Hg biomagnifies in the trophic chain and can represent a serious risk for human health and biota.