The purpose of the present study is to extend knowledge on the adverse effects of nanoparticles by evaluating genotoxicity as environmental risk assessment in Oreochromis mossambicus. Fish were exposed to sublethal concentrations of the selected nanoparticles, namely silicon dioxide (SiO2NPs-12mg/L), aluminium oxide (Al2O3NPs-4mg/L), titanium dioxide (TiO2NPs-16.4mg/L) and iron oxide (Fe3O4NPs-15mg/L) for short-term (24, 72 and 96 h) and long-term durations (15, 30 and 60 days). Genetic damages such as cytoplasmic, nuclear and DNA damage were measured in the erythrocytes of fish by using standard genotoxicity tests such as micronucleus test and comet assay. The frequencies of micronuclei along with nuclear and cytoplasmic abnormalities were scored and compared with the control group. The intensity of micronuclei along with other nuclear and cytoplasmic anomalies are found to be increased significantly (p<0.05) in time-dependent manner in all exposure groups when compared to the control group, thereby indicating chromosomal damage as a result of contact with nanoparticles. The tail length and percent of tail DNA within the comet significantly (p<0.05) increased in time-dependant manner after exposure to all nanoparticles, demonstrating an increase in DNA damage. Taken together, by using micronucleus test and comet assay, it is evident that the selected nanoparticles at sublethal concentrations induced genetic damage in Oreochromis mossambicus.
