Mercury from illegal gold mining threatens 951 Amazon communities, analysis finds

A new analysis spanning three Amazon river basins has mapped mercury contamination linked to illegal gold mining across 951 Indigenous and riverside communities in Peru, Bolivia and Brazil, according to Mongabay. The review combined 39 scientific studies published between 1997 and 2024, drawing on more than 7,700 human hair or blood samples and nearly 6,000 fish tissue samples along 2,763 kilometers of the Madre de Dios, Beni and Madeira rivers.

Of 249 communities with documented exposure, 88% exceeded the World Health Organization's safe mercury threshold; a further 702 nearby communities are considered at risk. The most contaminated sample, from a Brazilian community, measured 75 times the WHO limit. Among pregnant women tested, average mercury levels exceeded the safe threshold more than tenfold, and nearly a third of children tested in one study showed levels linked to cognitive deficits.

Illegal miners use mercury to separate gold from river sediment, then dump it back into the water; gold prices surpassing $5,000 an ounce in January 2026 have accelerated the mining boom. Researchers say government responses remain minimal — Peru budgeted under $500,000 for mercury screening despite estimating over 10 million people affected, and Bolivia has no plan to phase out mercury use despite being its largest global importer.

"Mercury contamination is a silent genocide against Indigenous peoples," said Eusebio Ríos Iviche of the Indigenous federation Fenamad.

Reporting by Alexa Vélez, Vanessa Romo and Daniela Quintero Díaz for Mongabay. Source: https://news.mongabay.com/custom-story/2026/09/new-analysis-maps-mercury-threat-to-951-amazon-communities-in-three-countries/