The toxicity of a synthetic industrial detergent and a corrosion inhibitor to brackish water fish (Tilapia guineensis)
The lethal effects resulting from incessant release of toxic surfactant-containing industrial chemicals into the Niger Delta Ecological Zone of Nigeria was studied using a laboratory toxicity test. The study employed the Organisation for Economic Development and Cooperation (OECD) 203 protocol. The test organism (Tilapia guineensis [fish]) was obtained from a brackish water environment and exposed to Neatex (industrial detergent) and Norust CR 486 (corrosion inhibitor) at concentrations of 6.25, 12.5, 25, 50, and 100 mg/L for 96 h. The ecological endpoint considered was mortality at 96 h, and the results obtained indicate that concentration and duration of exposure influenced the effects of the test chemicals. The 96-h lethal concentration (LC50) values for the industrial detergent and corrosion inhibitor were 46.52 ± 2.16 and 13.95 ± 0.80 mg/L, respectively. Differential toxicity was observed between the industrial detergent and corrosion inhibitor at the level of F (1,28) = 8.22, P < 0.05, with the corrosion inhibitor exhibiting a higher toxicity level. The brackish water fish were more sensitive to Norust CR 486 than to the industrial detergent. The mean mortality rate in response to the test chemicals was significantly higher than that to the control treatment at F (2,42) = 42.07, P < 0.05. The observed concentrations are indicative of early warning signs of water quality deterioration, as well as ecological effects on aquatic organisms.
Key words: Toxicity, fish, Tilapia guineensis, surfactant, industrial detergent, corrosion inhibitor