Microplastic Assessment in Liver, Kidney, Brain, and Muscle Tissue of the Fish Species Cyphocharax Voga

Microplastic (MP) pollution represents an emerging threat to aquatic ecosystem health. This study investigated MP concentrations in liver, brain, kidney, and muscle tissue of Cyphocharax voga individuals collected from the Sinos River, a water resource located in an urbanized region of southern Brazil. Using Nile Red staining and fluorescence microscopy, MP concentrations per gram were determined and MPs were identified by form and size. The highest mean MP concentration per gram was observed in brain tissue (192 ± 124 MP/g), followed by liver (65 ± 37 MP/g), kidney (47 ± 25 MP/g), and muscle tissue (39 ± 24 MP/g). Analysis revealed significant differences in MP concentration between fish sexes in liver and brain tissues. A statistically significant correlation was observed between kidney and liver (r = -0.520, p = 0.019), as well as between kidney and brain (r = -0.424, p = 0.039). Regarding MP morphology, fragments were the predominant form across all organs and muscle tissue, significantly different from all other forms (foams/films, spheres, and fibers). These results demonstrate MP presence in all sampled tissues and highlight the brain as a sensitive organ for biomonitoring purposes. This work provides critical insights into MP occurrence in freshwater fish that may inform future studies on the hazards these pollutants pose to aquatic environments, as they may serve as models for other vertebrates and potentially humans.