Lack of genotoxicity of iron oxide maghemite (γ-Fe₂O₃) and magnetite (Fe₃O₄) nanoparticles to Oreochromis niloticus after acute exposures

Abstract

Iron oxide nanoparticles (FeO-NPs) are widely used in scientific and technological fields. Environmental concerns have been raised about residual FeO-NPs levels as their toxicity and bioaccumulative potential are not well understood. Oreochromis niloticus were exposed to nanoparticles of γ-Fe₂O₃ and Fe₃O_4. Micro-CT 3D image and grayscale graphic assessments revealed the accumulation of radiopaque material in the digestive tract of fish exposed to FeO-NPs. Histological analysis showed the presence of such NPs in the hepatopancreas, gills, kidneys, and muscles. No genotoxicity occurred, through micronucleus test and comet assay in peripheral erythrocytes. Body clearance was confirmed by iron-content reduction in organisms exposed to FeO-NPs after recovery period. No tissue injuries were observed in the exposed animals which may be attributed to the absence or low toxicity of iron oxide nanoparticles under the study conditions. O. niloticus showed tolerance to sublethal exposures to FeO-NPs.

Keywords:
Magnetite; maghemite; tilapia fish; nanotoxicology; nanoparticles