Assessment of Genotoxic Effects of Pesticide Residues and Related Haemato-Biochemical Parameters on Farmed Nile Tilapia (Oreochromis Niloticus L.) in Kafrelsheikh Governorate, Egypt

Fish genotoxicity biomarkers are valuable parameters for environmental risk assessment. The aim of the current study was to determine the levels of organochlorine and organophosphorus pesticide residues in water and Nile tilapia fish samples collected from two fish farms in Kafrelsheikh governorate, Egypt. Also to detect the genotoxic effect on different fish tissues using comet assay and DNA fragmentation, as well as the haemato-biochemical changes of the sampled fish. A large number of pesticide residues were detected both in the water and fish samples with high incidence of organochlorine compounds especially endrin, heptachlor epoxide, hexachlorobenzene (HCB), and p,p′-DDE. While the haematological parameters revealed a significant decrease in RBCs, PCV, HB, neutrophilia, lymphopenia and monocytosis. A Significant increase in the ALT, AST, urea and creatinine indicating hepato-toxicity and kidney damage. The phagocytic assay revealed a significant decrease in both phagocytic activity (PA) and phagocytic index (PI) (P 0.05). The comet assay showed higher tail moments in the gills. The obtained results indicated that continuous exposure of the farmed Nile tilapia to different pesticide residues resulted in significant haemato- biochemical alterations as well as significant damage of the DNA in vital organs like gills and liver.