Evaluation of Acute Toxicity and Histopathological Impact of Diclofenac Exposure in Freshwater Fish Channa punctatus
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Abstract
Pharmaceuticals have emerged as priority pollutants of the environment all over the world in recent times. Diclofenac is a non-steroidal anti-inflammatory drug that has been usually detected in surface waters in the range of ng/l to µg/l. There is much experimental evidence of its toxicity in the aquatic flora and fauna. The objective of the present study is to investigate the acute toxic effect of the drug, Diclofenac in the freshwater fish, Channa punctatus. The fish were exposed to ten different concentrations of Diclofenac for 96 hours. The median lethal concentration value was evaluated by Probit analysis. The histological effect of Diclofenac was observed in the gill tissue on exposure to sub-lethal and median-lethal concentrations of diclofenac for a period of 96 hours. The fish exposed to sublethal concentrations of Diclofenac have shown marked pathological changes in the gills. Several cuts were also observed in secondary gill lamellae. There was a tendency for lamellar fusion and disorganised secondary gill filaments. The lamellae have turned into club shape which indicates the progressive degeneration of cells in the gill. The pathological changes observed in the fish exposed to lethal concentration are lamellar fusion, disruption of the epithelial layer, hyperplasia and cellular necrosis. There was bulging in the tip of primary gill filaments, distortion of the shape of secondary filaments, necrosis in pillar cell nucleus and vacuolization in the secondary gill epithelium. The findings of the study reveal that the drug Diclofenac has toxic potential and can alter the structural integrity of the tissues in the fish. Diclofenac in aquatic environments would cause negative impact on non-target organisms like fish.