Ecotoxicity and recovery of Poecilia reticulata exposed to cosmetic effluent, graphene oxide, iron oxide nanoparticles and magnetic graphene oxide.

Ecotoxicological studies involving nanomaterials (NMs), particularly magnetic graphene oxide (GOmag), and their interactions with pollutants in living organisms have gained increasing attention due to their potential environmental applications and possible biological effects. Thus, the present study evaluated the toxicity of graphene oxide (GO), iron oxide nanoparticles (IONPs), cosmetic industry effluent (EFL), and GOmag in the presence of EFL using mutagenic biomarkers in erythrocytes and histopathological biomarkers in the gills of juvenile female Poecilia reticulata. To determine the median lethal concentration (LC50), an acute toxicity test was initially conducted with EFL at concentrations of 100, 50, 25, 12.5, and 6.25 mg/L, resulting in an estimated LC50 of 8.39 mg/L. Based on this result, an exposure concentration of 4.2 mg/L, was selected for the subsequent experiment. Subsequently, fish were exposed for 7 days to the following treatments: control, GO (0.3 mg/L), IONPs (0.3 mg/L), EFL (4.2 mg/L), and GOmag + EFL (0.3 mg/L + 4.2 mg/L), followed by a 7-day post-exposure period in reconstituted water. A significant occurrence of erythrocytes presenting lobed, segmented, and kidney-shaped nuclei was observed according to treatment and exposure period. Histopathological analyses revealed the presence of lamellar aneurysms, melanomacrophages, ionocyte hyperplasia, and vasodilation in the gills. During the post-exposure period, all exposed groups showed a tendency toward recovery, evidenced by a reduction in both hematological and histopathological alterations. Furthermore, gill lesions were less frequent in the GOmag+EFL group than in the EFL group. However, this pattern was not observed in erythrocytes, where nuclear abnormalities occurred at a higher frequency in the GOmag + EFL group than in the EFL-only group. These findings indicate that the biological effects associated with GOmag may vary according to the biomarker analyzed and highlight the need for further ecotoxicological and chemical investigations to better understand its interactions with environmental contaminants and its potential applicability in remediation strategies.