Amazon Fish Contaminated With Toxic Metals Threaten Riverine Communities' Health

SANTARÉM, Brazil - March 4, 2026 - PRLog -- A new peer-reviewed study published in ACS Omega exposes dangerous levels of toxic elements in fish consumed daily by riverine communities in the Brazilian Amazon.

Researchers from the Federal University of Western Pará (UFOPA) and collaborators analyzed arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in six popular fish species collected directly from local fishermen in five municipalities of western Pará — regions impacted by artisanal gold mining and bauxite extraction.

Key findings:

• Mercury exceeded Brazilian legal limits (0.5–1 mg/kg) in most carnivorous species, such as peacock bass (tucunaré).
• Under realistic high fish consumption in Amazon riverine diets (~462 g/person/day), non-cancer health risks up to 30 times higher than safe limits. Combined risks from multiple elements exceed safe lifelong exposure thresholds.
• Cancer risks surpass the acceptable threshold in 25% of high-consumption scenarios, primarily driven by arsenic.
• In contrast, Brazil's national average fish consumption (~24 g/day) results in low risks, highlighting that national guidelines do not account for extreme local intake patterns.

The contamination stems from mercury used in gold mining, arsenic and cadmium release from bauxite processing, and sediment mobilization due to deforestation and land-use changes. Traditional fish-based diets, vital for nutrition and culture in these communities, now pose hidden health threats including neurological damage from mercury and increased cancer probability from arsenic.

"Fish provides essential protein and nutrients, but pollution is turning this staple food into a hazard for vulnerable populations," said lead author Fábio Edir Amaral Albuquerque from UFOPA. "Urgent monitoring, tailored public health guidance, and efforts to reduce exposure, without abandoning cultural practices, are essential to protect Amazonian riverine people."

The full open-access article is available at: https://pubs.acs.org/doi/10.1021/acsomega.5c10676