The Amazon suffers from the occurrence of mining along its hydrographic routes, which releases toxic substances into the aquatic environment. The objective of this study was to evaluate the risk of contamination by As and Hg that indigenous peoples are exposed to through the consumption of fish in an area impacted by mining activity in the basin of the Curuá and Baú Rivers, Altamira-PA. In total, 55 fish specimens and 30 surface water samples were collected. The decomposition of the fish samples was done by wet method with the use of nitric acid, hydrogen peroxide, and microwaves. The quantification of total mercury (THg) and total arsenic (TAs) was carried out by inductively coupled plasma optical emission spectrometry with vapor generation (VG-ICP OES). The methodology proposed by the U.S. Environmental Protection Agency was used. The results showed that TAs presents safe levels; however, THg presents a sample with levels up to (4.6 µg g 1), exceeding the permitted levels (1 µg g 1). The risk assessment shows that only the consumption of fish, linked to Hg, represents the existence of deleterious risks to indigenous peoples (hazard quotient (HQ)) > 1). Bioaccumulation factor (BAF) in fish represents a risk to indigenous people, because of the Hg’s presence. The study identified that illegal mining activities are responsible for Hg pollution in the Baú and Curuá Rivers. The fish species analyzed can be used as bioindicators of Hg in the rivers, which is relevant for making environmental and public health policy decisions.

This study provides a risk assessment and risk maps related to the consumption of water contaminated by Al, Ba, Fe and Pb in an industrial area in the Brazilian Amazon. A total of 120 samples of drinking water were collected from 26 locations in the municipality of Barcarena, Pará State. Multiple elements were analyzed by inductively coupled plasma optical emission spectrometry. The quantifiable elements in the samples were Al, Ba, Fe and Pb. Risk assessment was performed according to U.S. Environmental Protection Agency (USEPA) procedures. Results indicate that the highest potential risk of non-carcinogenic adverse health effects for Al was in São João Island; for Ba, Fe and Pb (hazard quotient (HQ) > 1) were in Porto da Balsa community, in the city of Barcarena and Distrito Industrial community, respectively. Maps showed that areas located near Barcarena’s industrial complex are the most affected by water contamination. Therefore, these populations are at higher risk of non-carcinogenic problems, especially children and the elderly, since the majority of the population resides in these areas. Geospatial analysis contributed to delimiting and analyzing risk-change trends in the region, expanding the scope of results to a decision-making process.