Relative toxicity of cigarette butts leachate and usefulness of antioxidant biomarker activity in Nile Tilapia Oreochromis niloticus (Trewavas, 1983)

Abstract

Relative acute toxicity of cigarette butts leachate, antioxidant biomarkers; superoxide dismutase (SOD), catalase (CAT), gluthathione (GSH)activity and lipid peroxidation (LPO), an index of malondialdehyde (MDA) were evaluated in Nile Tilapia (Oreochromis niloticus) exposed to two selected commonly consumed brand of cigarettes butts in smoked and unsmoked conditions(SCB 1/ 2 and UCB 1/2) respectively. Under laboratory condition acute toxicity was conducted over a period of 96hrs. Antioxidant activity and lipid peroxidation were based on the derived 96h LC₅₀ value over a period of 28days. On the basis of 96hrs LC₅₀ value, SCB 1 was found to be the most toxic (1.346 cigarette butt/l) followed by SCB 2 (2.271cigarette butt/l), UCB 2 (7.313cigarette butt/l) and UCB 1 (5.559cigarette butt/l) against O. niloticus. The results of SOD and CAT activity under the sublethal concentration (1/10^th and 1/100^th of 96hrs LC₅₀) of cigarette butt leachate showed significantly(P<0.05) decreased activity in liver and gills compared to the control group whereas GSH in the liver and gill was induced significantly (P < 0.05) within 7-14days compared to 21-28days. MDA increased significantly (P< 0.05) in the liver and gill compared to control group. These findings indicate high oxidant activity on the fish, explaining the enormity of the impact of cigarette butt leachates in the environment and the significance of using a set of integrated biomarker in evaluating oxidative stress in aquatic ecosystem.

Keywords: Cigarette Butt Leachate, Acute toxicity, Biomarkers, Oxidative stress