# More Danger Than Meets the Eye: Potentially Toxic Element Contamination in Fish from the Western Pará Poses Significant Hazards to Local Communities

## TL;DR

Fish in the Amazon's western Pará region contain high levels of toxic metals, posing health risks to local communities who consume large amounts of fish.

## Contribution

This study quantifies toxic metal contamination in fish and evaluates health risks under regional consumption patterns.

## Key findings

- Mercury concentrations exceeded legal limits in most carnivorous fish species.
- Noncarcinogenic risks (THQ > 1) were high under the Amazon consumption scenario.
- 25% of samples exceeded carcinogenic risk thresholds due to arsenic exposure.

## Abstract

The Amazon basin
is undergoing rapid environmental transformation
driven by agricultural expansion and mining activities, resulting
in increased concentrations of toxic metals in aquatic ecosystems.
This study quantified arsenic (As), cadmium (Cd), mercury (Hg), and
lead (Pb) in six fish species and evaluated associated noncarcinogenic
and carcinogenic health risks under two consumption scenarios: the
Amazon Scenario (462 g/person/day) and the Brazil Scenario (24 g/person/day).
Fish were sampled in five municipalities in western Pará, which
differ in the intensity of the gold and bauxite mining activities.
The results show that Hg concentrations exceeded legal limits in most
carnivorous species; the target hazard quotients (THQ) indicate lifelong
noncarcinogenic risk (THQ > 1) in nearly all samples under the
Amazon
Scenario, peaking at 28.97 for Cichla ocellaris from Porto Trombetas. Total target hazard quotients (TTHQs) also
exceeded the safety threshold of 1 for all species in the Amazon Scenario,
indicating significant noncarcinogenic risk for local consumers, whereas
risks remained acceptable under the national consumption pattern.
Carcinogenic risk analysis revealed that 25% of samples in the Amazon
Scenario exceeded the 1 × 10–4 threshold, primarily
due to arsenic exposure. These findings demonstrate that traditional
fish-based diets expose Amazonian riverine populations to hazardous
levels of potentially toxic elements, underscoring the need for integrated
environmental monitoring, public health surveillance, and nutritional
guidance tailored to high-consumption communities.