Toxicological assessment of four common household surfactants on Clarias gariepinus (Burchell, 1822) and Oreochromis niloticus (Linnaeus, 1758)

The acute toxicity of four common household liquid detergents coded as (FL, ML, MF and LC) was evaluated on two fish species; African Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus) fingerlings in a static bioassay. During the exposure period (96 hours), there was a remarkable rise of alkalinity from 22.00 mgL-1 to 62.50 mgL-1 while dissolved oxygen decreased with increased concentration. Behavioral changes such as restlessness, rapid swimming, loss of balance, opercula ventilation, respiratory distress and hemorrhaging of gill filaments were observed before mortality. Based on 96 hr LC50, FL (0.009 ml/L), was the most toxic followed by ML (0.014 ml/L), MF (0.056 ml/L) and LC (0.168 ml/L) against O. niloticus whereas MF (0.021 ml/L) was the most toxic followed by ML (0.033 ml/L), FL (0.038 ml/L) and LC (0.364 ml/L) against C. gariepinus in descending order. In terms of the sensitivity, O. niloticus fingerlings were more susceptible to the detergents than C. gariepinus fingerlings. The use of detergents cannot be discontinued. However, better methods of disposing the ‘after wash' needs to be worked out. At the present rate at which they are manufactured and introduced into the aquatic environment indiscriminately, aquaculture fish species could seriously be threatened.Keywords: Acute toxicity, detergents, Oreochromis niloticus, Clarias gariepinus, behavioral change

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

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 (1/10th and 1/100th 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 stres

Single and joint action toxicity evaluation of insecticide and laundry detergent against Poecilia reticulata

In laboratory bioassays, single action toxicities of an insecticide (Apicide [A]) and two laundry detergents (Persil [P] and Klin [K]) as well as their joint action toxicity studies in binary (1:1; 1:4) and triple (1:1:1) mixtures were evaluated against Poecilia reticulata (Guppy). Joint action toxicity mortality data was analyzed using Synergistic Ratio (SR), Concentration – Addition (RTU) and Isobolograms models. On the basis of 96hr LC50 mortality data from single action studies, showed that A was the most toxic (0.00137mg/l) followed by P (0.773mg/l) and K (28.841mg/l). The joint action toxicity data showed a synergistic effect in mixtures of insecticide and detergents in all ratios (1:1, 1:4, 1:1:1) than when acting alone. In descending order of toxicity it was revealed that Apicide/persil (1:1; 0.00079mg/l)>Apicide/ Persil/Klin (1:1:1; 0.00093mg/l)>Apicide/Klin (1:1; 0.00094mg/l)>Apicide/ Persil (1:1; 0.00098mg/l)>Apicide/ Klin (1:4; 0.00106mg/l). The subjection of the 96h LC50 values of test compound mixtures based SR and RTU showed that interaction of mixtures in various ratios (1:1, 1:4, 1:1:1) tended towards synergisms (SR>1; RTU>1) respectively. Further analysis based on the isobologram model was in conformity with RTU and SR models. The significance of this study showed the relevance of joint action toxicity studies in setting realistic safe limits in order to protect aquatic organisms. Therefore, proper disposal and management strategies for wastes should be enforced.Keywords: Bioassay, Detergent, Insecticide, Toxicity, Poecilia reticulat