Abstract
This study assessed the levels of oxidative stress biomarkers in gills and liver, as well as the activities of transaminases in the liver of Nile tilapia (Oreochromis niloticus), exposed to pharmaceutical effluents. The pharmaceutical effluents were collected from two pharmaceutical industries in Lagos, Nigeria. The assessment of physicochemical characteristics of the effluents indicated that some parameters were not in accordance with NESREA limits. The acute toxicity studies showed that 96hrLC50 values of “effluent A” and “effluent B” were 27.0 ml/L and 18.0 ml/L respectively. The juveniles of O. niloticus were exposed to 1/100th and 1/10th LC50s of the two effluents for a period of 14 and 28 days. These concentrations significantly increased the level of the lipid peroxidation product, malondialdehyde. There was also inhibition of the activities of superoxide dismutase and catalase as well as significantly lower levels of reduced glutathione after 28 days. The levels of the transaminases (aspartate aminotransferase and alanine transaminase) were elevated in the liver of the fish after the exposure to the effluents. The present findings showed that the wastewater caused oxidative stress and hepatocellular damage in the fish suggesting potential ecotoxicological risks of the wastewater to aquatic organisms.
Highlights
IntroductionPharmaceutical effluents contain a vast number of chemicals and microorganisms depending on the drug that is being produced and are toxic to biological organisms due to the presence of salt, surfactants (detergents, emulsifiers and dispersant), ionic metals and their metal complexes, organic chemicals, biocides, unmetabolized drugs, toxic anions and microorganisms [6] [7] [8] [9]
Some of these components can combine with unsaturated fatty acids of phospholipids located in the cell membranes [10]. This leads to oxidative damage and the production of malondialdehyde and the oxidative stress is countered by the action of antioxidative stress enzymes such as superoxide dismutase (SOD) and catalase (CAT) [11]
The results of the physicochemical characterization of pharmaceutical effluent A indicated that suspended solids (90.1 mg/L), nitrate (225 mg/L), sulphate (450 mg/L), phosphate (164 mg/L), total hardness (600 mg/L) and cobalt (0.725 mg/L), colour (2490 PCU), turbidity (402 NTU), alkalinity (250 mg/L) were above NESREA limits [26] (Table 1)
Summary
Pharmaceutical effluents contain a vast number of chemicals and microorganisms depending on the drug that is being produced and are toxic to biological organisms due to the presence of salt, surfactants (detergents, emulsifiers and dispersant), ionic metals and their metal complexes, organic chemicals, biocides, unmetabolized drugs, toxic anions and microorganisms [6] [7] [8] [9]. Some of these components can combine with unsaturated fatty acids of phospholipids located in the cell membranes [10]. The term waste water used in the study represents treated effluents collected from the discharge point before entry into the water body
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