Chronic Exposure to No-Effect Concentration of Diazinon Induced Histological Lesions in Organs of <i>Clarias</i> <i>gariepinus</i>

Abstract

In all parts of the world pesticides have been found in the aquatic ecosystem and scientific evidence has also shown that they can enter the food chain. Diazinon is an organophosphate pesticide, widely used in agriculture to control a wide variety of suckling and leaf eating insects and recently in fish culture to suppress some parasitic diseases; nevertheless, there is little study on its adverse effect on fish. In this study, seventy-two (72) apparently healthy catfish comprising adult and juvenile of both sexes were used to set up triplicate experimental groups of those exposed to culture water alone (control group), fish exposed to predetermined no-effect concentration (0.405 ppm) of Diazinon (test group). The fish were exposed for 28 days and fish were sacrificed and organs harvested on days 21 and 28 to determine the effect of long-term exposure to diazinon on organ histology. Histological changes observed in diazinon-exposed catfish were hyperplasia and fusion of the gill epithelium, hyperplasia of mucoid producing cells and aggregation of melanin pigment in the skin. Histological lesions were also seen observed in other organs, including severe diffuse cellular swelling and fatty degeneration of the liver, interstitial congestion of the kidney, carbon deposit on the wall of the heart and multifocal haemorrhage. The water quality of the control was not significantly different from that of the test group throughout the experiment. The lesions detected in cells, tissue, or organs represent an integration of cumulative effects of physiological and biochemical stressors. The histological alterations

Histopathological analysis of selected organs of Oreochromis niloticus due to sub-lethal industrial effluents exposure

“…Physico-chemical analysis revealed that these effluents were highly toxic, not only to aquatic organisms but the entire web chain including human beings who are primary consumer of fish. Aquatic species have been deemed an outstanding and cost-effective model system because of their ability to concentrate, store, and metabolize water-borne contaminants (26) for analyzing the carcinogenic, mutagenic and toxic potential of pollutants (27) and (28). Fish exposed to chemical pollutants had a variety of lesions in various organs (29).…”