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

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.