Haemato-histological Alterations in Laboratory Population of Clarias gariepinus on Exposure to Varying Concentrations of Diethyl Phthalate

Abstract

Diethyl phthalate (DEP) is a synthetic organic compound widely used as plasticiser in various consumer products and it is known to act as an endocrine disruptor. Indiscriminate disposal of DEP-made products has harmful effects on fish and other aquatic organisms. Hence the present study was conducted to assess the toxic impact of DEP on general physiology of Clarias gariepinus. The fish were treated with different sub lethal concentrations (26.0, 34.5, 43.25, 53.8 and 62.5 µL/L) of DEP after series of range finding and acute studies. The LC50 value of DEP-exposed C. gariepinus was estimated to be 1.803 and 2.181 µL/L respectively of acute and chronic toxicities. Acute and chronic toxicity tests revealed disrupted normal swimming patterns, induced erratic movements, and impaired opercula function which may have implications for ecological functions of C. gariepinus. WBC count of 22.93±0.73 cells/mm³ was obtained in the control group and the treatment groups ranged from 22.97±3.00 to 33.40±1.16 cells/mm³. The P-value for WBC is 0.191, indicating no statistically significant difference between the control and treatment groups. The red blood cell (RBC) count in the control group was 1.50±0.29 million/mm³. The treatment groups varied, with the highest value (1.89±0.23 million/mm³) at 62.5 µL/L diethyl phthalate. The P-value is 0.548, indicating no significant differences in RBC counts between groups. Haemoglobin (HGB) levels in the control group were 4.93±1.13 g/dL. Treatment group values fluctuated, with the highest (6.93±1.36 g/dL) at 26 µL/L. The P-value of 0.639 indicates no significant difference in haemoglobin levels across the groups. The control group showed a haematocrit (HCT) level of 20.13±3.34%. Treatment groups varied, with no clear trend. The P-value is 0.520, suggesting that diethyl phthalate did not significantly affect haematocrit. Varied degrees of histological degradations like gill lamellae hypertrophy, hepatic vacuolation in liver and tubular degeneration in the kidneys were recorded and these anomalies were DEP concentration dependent. This work has revealed that DEP exerts its toxic effects even at sub lethal concentrations and this shows that Conclusively, DEP exerted dose-dependent toxic effects that disrupted normal pphysiological functions. Therefore, indiscriminate usage of DEP in environment should be monitored with strict vigilance.