COMPARATIVE ECOTOXICITY OF SELECTED DOMESTIC DETERGENTS ON FRESH WATER FISH AND MICROORGANISMS

Abstract

This study investigated the ecotoxicological effects of selected domestic detergents (Ariel, Viva, Morning Fresh, and Mama Lemon) and Sodium dodecyl sulphate (SDS)as reference chemical on freshwater microorganisms—Nitrobacter sp., Escherichia coli, and Staphylococcus sp.—and fishes—Schilbe mystus, Synodontis eupterus, and Synodontis membraneceus—collected from River Niger, Asaba, Delta State, Nigeria. Acute toxicity bioassays were conducted using concentrations ranging from 10 ppm to 100,000 ppm, while physicochemical parameters of the water were also assessed. Results revealed that all detergents exhibited significant toxicity, with 100% mortality observed at higher concentrations. The order of sensitivity among the test organisms was Schilbe mystus > Synodontis eupterus > Synodontis membraneceus > Nitrobacter sp. > Staphylococcus sp. > E. coli. Among detergents, Mama Lemon caused the highest mortality in fishes (LC₅₀ Schilbe mystus 12,500.13ppm, LC₅₀ results for Synodontis eupterus 12500.25ppm and Synodontis membraneceus 12501.5ppm) whereas Ariel showed the greatest toxicity toward microorganisms (with LC₅₀ for Nitrobacter sp. 3, 532.11ppm, Staphylococcus sp. 7,210.73ppm and E. coli. 16,832.35ppm). Detergent exposure led to inhibited nitrification, membrane disruption, and cellular lysis, especially in Gram-negative bacteria. The findings indicate that domestic detergents contribute significantly to aquatic pollution, reducing microbial populations vital for nutrient cycling and threatening fish biodiversity. It is there recommended amongst others that biodegradable detergents be promoted, effluent discharge be strictly regulated, and continuous monitoring of freshwater systems be enforced to prevent ecological imbalance and safeguard human health.