Morphological abnormalities in erythrocytes as a preliminary indicator of genotoxicity of nano-tire rubber in Nile tilapia (Oreochromis niloticus)

Despite recent research interest in the toxic effects of tires, there is a lack of data on the genotoxicity of tire rubber particles in aquatic organisms. This study aimed to detect the cellular and genetic abnormalities affecting erythrocytes in Nile tilapia (Oreochromis niloticus) exposed to tire rubber nanoparticles (TRNPs ≤1 μm) using a micronucleus assay. Fish were divided into 3 groups: the first (control) was not exposed to TRNPs, the second was exposed to different concentrations of TRNPs in the water (5, 10, and 30 mg/Lw, respectively), and the third was exposed to different concentrations of TRNPs mixed with the feed (100, 150, and 300 mg/kg of the diet, respectively) for a period of 15 days. The frequencies of altered erythrocytes, nuclear lesions, and cytoplasmic abnormalities were significantly lower in the control group compared to those observed in the blood of fish of the exposure groups. In most of these abnormalities, high abundance and statistically significant differences were in the concentrations of the third group, while the general distribution and abundance of these abnormalities were higher in the second group. A direct correlation was found between an increase in these abnormalities and the statistically significant differences increased in a concentration-dependent manner of TRNPs in both groups. These findings provide a preliminary indication of the harmful effects of nano-tire rubber on fish, thereby laying the groundwork for further environmental and biological toxicological research on this pollutant.