Mercury contamination endangers Indigenous Amazonian communities: a systematic review

In the Amazon, gold is predominantly found in alluvial deposits, so miners use liquid mercury (Hg) to process this metal, occasionally contaminating rivers, lakes, aquatic organisms, and humans, including Indigenous communities that depend on natural resources. This systematic review aimed to analyze the potential health risks associated with Hg levels found in biological samples from Indigenous populations and animals consumed by these populations in the Amazon biome. A search was carried out to find articles between July and September 2024 using the following databases: Scopus, PubMed, ScienceDirect, and Web of Science. Levels of mercury were found in hair and urine in Indigenous communities from Amazon, such as Colombia, which had the highest average in one of the communities analyzed in hair (22.2 ± 1.7 µg g^-1). Studies revealed averages above the safe levels in hair established by the World Health Organization, of 6 µg g^-1, in three countries (Brazil, Colombia, and Peru). The levels in wild animals were lower than those found in fish, mainly carnivores, where five species had Hg levels above the limit of 1 ppm established for predatory fish (Pygocentrus nattereri, Platynematichthys notatus, Boulengerella cuvieri, Ageneiosus brevifilis, and Cichla ocellaris). Assessments of neurological manifestations of mercury (Hg) poisoning were carried out in Brazil (Yanomami and Munduruku villages) and Peru (Maizal, Cacoatal, and Yomibato villages). Therefore, it is essential for the countries within the Amazon region to work together on protecting Indigenous territories in order to prevent these activities from further endangering the survival of these vulnerable populations.