Integrative toxicity characterization of gamma alumina-based nanomaterials on a native fish Cnesterodon decemmaculatus (Pisces: Poeciliidae)

Gamma alumina-based nanoparticles (γ-Al2O3 NPs) are widely produced nanomaterials (NMs) with multiple applications. Their release into the environment raises concerns about fate, ecotoxicity, and persistence. Assessing their effects on native species is therefore essential. This study evaluated the sublethal effects of the nanoceramic catalyst Ni/γ-Al2O3 (NC) and its synthesis precursors, γ-Al2O3 support (SPC) and NiO/γ-Al2O3 precursor (PC), on Cnesterodon decemmaculatus, a fish broadly distributed in South American streams. Biomarkers of oxidative stress, neurotoxicity, and aluminium (Al) and nickel (Ni) accumulation were measured in fish exposed to acute sublethal concentrations. The Integrated Biomarker Response (IBR) index was used to integrate responses and assess overall stress. Results showed inhibition of glutathione S-transferase in all NM exposures, and of superoxide dismutase in PC at 50 mg/L and NC at 100 mg/L. Catalase activity increased in 100 mg/L SPC and 50 mg/L NC, and lipid peroxidation in 100 mg/L SPC. Acetylcholinesterase activity was significantly inhibited by all treatments. Accumulation of Al significantly increased in fish exposed to all NMs, while Ni levels increased under both concentrations of PC and NC. In conclusion, this study demonstrates the metal accumulation of these NMs in specimens of C. decemmaculatus and the ability to cause alterations in the antioxidant response, oxidative stress damage, and neurotoxic effects. This study provides a framework for ecotoxicological assessment of NMs exposure, which is essential to ensure environmental safety.