Mercury Exposure and Health Effects in Indigenous People from the Brazilian Amazon—Literature-Scoping Review

Background and purpose: Indigenous people in the Brazilian Amazon are exposed to mercury by eating methylmercury-contaminated fish. The lack of information on the health effects of prolonged exposure to mercury hinders the implementation of mitigation programs offered by the Brazilian government. This article aims to evaluate the studies that have investigated mercury exposure in indigenous people living in the Brazilian Amazon. Methods: A scoping review of the literature was conducted from studies published between 1995 and 2024 in Portuguese, English, and Spanish that evaluated mercury (Hg) concentrations in hair samples in indigenous people from the Brazilian Amazon. Results: Using total mercury (TotalHg) values in hair samples, we analyzed exposure levels, prevalence, and toxic effects. We found 15 epidemiological studies with a cross-sectional design and sample sizes ranging from 31 to 910 participants. Four studies involved children and mothers, four of which were associated with clinical outcomes and three of which analyzed genetic polymorphism. Most of the communities evaluated had a high prevalence of mercury exposure, showing levels ranging from 0.8 to 83.89 µg/g, and the highest average TotalHg concentration was found among the Kayabi. Mercury was associated with hypertension, cognitive disorders, worse mental health indicators and central and peripheral neurological disorders. Conclusions: It is concluded that indigenous people in the Brazilian Amazon experience exposure levels that are causing damage to their health, and control measures must be adopted to prevent the situation from worsening.