Co-exposure of iron oxide nanoparticles and glyphosate-based herbicide induces DNA damage and mutagenic effects in the guppy (Poecilia reticulata)

Abstract

Iron oxide nanoparticles (IONPs) have been tested to remediate aquatic environments polluted by chemicals, such as pesticides. However, their interactive effects on aquatic organisms remain unknown. This study aimed to investigate the genotoxicity and mutagenicity of co-exposure of IONPs (γ-Fe₂O₃ NPs) and glyphosate-based herbicide (GBH) in the fish Poecilia reticulata. Thus, fish were exposed to citrate-functionalized γ-Fe₂O₃ NPs (0.3 mg L^-1; 5.44 nm) alone or co-exposed to γ-Fe₂O₃ NPs (0.3 mg L^-1) and GBH (65 and 130 μg of glyphosate L^-1) during 14 and 21 days. The genotoxicity (DNA damage) was analyzed by comet assay, while the mutagenicity evaluated by micronucleus test (MN test) and erythrocyte nuclear abnormalities (ENA) frequency. The co-exposure induced clastogenic (DNA damage) and aneugenic (nuclear alterations) effects on guppies in a time-dependent pattern. Fish co-exposed to NPs and GBH (130 μg glyphosate L^-1) showed high DNA damage when compared to NPs alone and control group, indicating synergic effects after 21 days of exposure. However, mutagenic effects (ENA) were observed in the exposure groups after 14 and 21 days. Results showed the potential genotoxic and mutagenic effects of maghemite NPs and GBH co-exposure to freshwater fish. The transformation and interaction of iron oxide nanoparticles with other pollutants, as herbicides, in the aquatic systems are critical factors in the environmental risk assessment of metal-based NPs.

Keywords: Biomarkers; Comet assay; Genotoxicity; Mixture toxicity; Nanomaterials; Nanotoxicity.