Assessing the potential toxicity of paint industry effluents to aquatic organisms using the whole effluent testing...

Point source effluent discharges from industries are major sources of pollutants in aquatic ecosystems. In this study, the whole effluent testing approach was used to assess the toxicity of paint industry effluents to fish. Effluents were collected from three paint industries at point of discharge into the environment. Bioassay procedures were used to assess the toxicity of the effluents to fish. Effluent B was the most acutely toxic to the fish with a 96 h LC₅₀ value of 3.50% dilution (v/v). The acute toxicity ranking of the effluents to the fish was B > C > A. Analysis of the biochemical parameters of fish exposed to sublethal dilutions of the effluents showed that the three effluents significantly (p < 0.05) enhanced the activities of liver function enzymes and oxidative stress enzymes in exposed fish. The levels of malondialdehyde, a substrate of oxidative stress, was also significantly (p < 0.05) higher in fish exposed to the effluents (3.87 ± 0.40, 4.99 ± 0.45, and 3.22 ± 0.57 U mg^-1 protein for effluents A, B, and C, respectively) compared to levels in control (1.24 ± 0.31 U mg^-1 protein). Results from this study have established that untreated or poorly treated paint industry effluents can be highly toxic to aquatic organisms, having the potential to disrupt normal functioning of organisms at low concentrations. The study highlights the advantages of whole effluent testing as a method that accurately predicts the toxic potentials of industrial effluents. This is vital for the adequate protection aquatic ecosystems.