Metal Accumulation, Liver Histopathology, and Human Health Risk Assessment Across Different Trophic Guilds in a Mining-Affected Neotropical River.

Metal pollution in aquatic environments represents a recurring global concern; however, traditional paradigms often assume linear bioaccumulation patterns that may fail under catastrophic contamination scenarios. This study evaluated metal concentrations in water, sediment, and tissues of 10 fish species from different trophic guilds in the Paraopeba River after the Brumadinho dam collapse. Multivariate analyses (principal component analysis [PCA], generalized linear model [GLM], and PERMANOVA) were used to explore associations between metal concentrations, ecological traits, and body size integrated with liver histopathology (Histopathological Alteration Index) and Human Health Risk Assessment. Results revealed that metal concentrations in water and fish tissues exceeded regulatory limits, whereas sediment acted as the main reservoir of metals, exhibiting higher concentrations than water. High-severity liver damage was concentrated in benthic piscivores and benthopelagic detritivores, exposing a complex interplay between biomagnification and direct substrate contact. Human Health Risk Assessments indicated unacceptable noncarcinogenic risks driven by aluminum (Al), along with elevated carcinogenic risks for chromium (Cr) and cadmium (Cd) for both adults and children in the region analyzed. These findings demonstrate that ecological traits were associated with differences in metal accumulation, liver damage, and public health threats, reinforcing the need for nonlinear models in postdisaster regulatory frameworks.