Albuquerque et al. 2026 — Toxic element contamination in Amazonian fish, western Pará, Brazil
This study measured arsenic, cadmium, mercury, and lead in 398 fish specimens representing six species from five municipalities in western Pará state, an Amazon region characterized by artisanal gold mining and industrial bauxite mining. Species included Cichla ocellaris (peacock bass), Pseudoplatystoma punctifer (spotted catfish), Arapaima gigas (arapaima), Serrasalmus sp. (piranha), Leporinus sp., and Hypostomus sp. (armored catfish). Mercury exceeded Brazilian regulatory limits in the majority of carnivorous species samples. The target hazard quotient (THQ) exceeded 1.0 in nearly all samples under the Amazon consumption scenario (462 g/person/day), indicating non-carcinogenic health risk to subsistence consumers who rely on these fish as their primary protein source. Approximately 25% of samples exceeded a 1×10⁻⁴ carcinogenic risk threshold, driven primarily by arsenic. The study highlights the intersection of artisanal gold mining mercury contamination and bauxite-related arsenic exposure in a region where fish consumption rates are among the highest globally.
Key numbers
- Total specimens: n = 398 across 6 species
- Municipalities sampled: 5 (western Pará state, Brazilian Amazon)
- Mercury: exceeded Brazilian regulatory limit (0.5 µg/g ww in non-predatory; 1.0 µg/g ww in predatory) in majority of carnivorous species
- THQ > 1 in nearly all samples at Amazon consumption scenario (462 g/person/day)
- Carcinogenic risk > 1×10⁻⁴ in approximately 25% of samples (arsenic dominant driver)
- Analytes: As, Cd, tHg, Pb (total, not speciated; inorganic/organic fractions not separated)
- Analytical method: ICP-OES or ICP-MS (muscle tissue digestion)
- Mercury note: tHg reported; MeHg not speciated but in predatory freshwater fish is predominantly MeHg
Methods (brief)
Muscle tissue samples digested with HNO₃/H₂O₂ in microwave system. Multi-element analysis by ICP. Health risk assessment used deterministic THQ methodology (US EPA) with Amazon consumption scenario (462 g/person/day) and a conservative urban Brazil scenario for comparison. Carcinogenic risk estimated for arsenic using IRIS slope factor. No mercury speciation performed.
Implications
Certification: Relevant to fish and seafood product categories where MeHg and As are primary analytes; demonstrates that artisanal gold mining regions produce fish with systematically elevated Hg exceeding regulatory limits.
Courses: High-value case study for subsistence fishing exposure scenarios; illustrates that consumption frequency and regional sourcing determine whether regulatory limits are meaningful protections for high-consumption communities.
App: Supports geographic risk weighting for fish sourced from Amazonian mining regions; carnivorous species (peacock bass, spotted catfish) carry higher Hg burden than detritivores and herbivores.
Microbiome: Not directly addressed.