Mercury Contamination and Co-exposures in the Amazon Basin: At the Center of the Planetary Environmental Crisis

Background: Mercury contamination remains a significant public health concern in the Amazon basin. This review synthesizes recent evidence on mercury exposure, health outcomes, and emerging co-exposures in the Amazon countries. Data were presented at the Annual Conference of Global Health in the Americas, organized by Florida International University in Cartagena, Colombia on September 15, 2023, at a virtual session of the Consortium of Universities for Global Health on November 29, 2023, and subsequently updated with further literature search. Findings: Reported mercury concentrations in fish range from 0.10 to 4.73 µg/g, while hair mercury levels in exposed populations span 3.07-24.6 µg/g. Cross-sectional studies among Indigenous and traditional communities consistently demonstrate associations between mercury biomarkers-primarily measured in hair and urine-and neurocognitive as well as neuromotor impairments. Additional evidence links mercury exposure to increased cardiovascular and metabolic risk. Genetic susceptibility, notably APOE4 and GSTP1 polymorphisms, may modulate mercury absorption and toxicity. Co-exposures to microplastics and agrochemicals are increasingly reported in the region, raising concern over synergistic toxic effects. However, scientific evidence on these combined exposures remains fragmented and insufficient. Conclusions and recommendations: To address this critical gap, we propose the formation of a cross-national scientific consortium to foster collaboration, enhance epidemiological capacity, and strengthen laboratory infrastructure. Crucially, efforts to address mercury contamination must center the voices of Amazonian Indigenous peoples, who bear the greatest burden of exposure while facing persistent social, environmental, and health inequalities. Meaningful engagement with these communities is essential to overcome marginalization and ensure that research, policy, and intervention strategies are culturally informed, equitable, and effective. Coordinated regional action is urgently needed to protect the health and rights of vulnerable Amazonian populations.