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ABSTRACT: The effects of endosulfan, a widely used organochlorine pesticide in the Niger-Delta ecological zone were examined on cortisol secretion, glutathione S-transferase and acetylcholinesterase enzymatic activities in the serum of a dominant fresh water fish species, Clarias gariepinus. Juveniles stage of C. gariepinus were used for the toxicity study. Lethal concentration of 50% mortality of sample (LC(50)) was determined using semi-static method. From the result of the LC(50) determination lower concentrations of endosulfan were prepared for sub-lethal test. Ten fish per test concentration in three replicates were exposed to varying concentrations of endosulfan (0.00, 0.0025, 0.005, 0.0075 and 0.01) μg/L. Signs of stress and mortality were monitored during the experimental duration. Cortisol levels, GST and AChE activities were measured spectrophotometrically. No visible changes in behaviour and appearance were observed in the treated fishes and no mortality recorded. Significant (p<0.05) declined in cortisol secretion was observed and the change in the concentration was dose and time dependent. Glutathione S-transferase activity was significantly (p<0.05) higher than the control and the concentrations increase with increased in concentration and exposure duration. No clear trend was observed in acetylcholinesterase activity. The findings showed that the cortisol levels and GST activity of test organism were affected by the test chemical and therefore could be considered as a suitable marker to evaluate the effect of organochlorine pesticide on fish and other aquatic organisms.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 11/2010; 49(9):1898-903. · 2.99 Impact Factor
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ABSTRACT: The toxic effects of industrial chemicals on three early life stages of an economically important fish, Tilapia guineensis were investigated using the Organisation for Economic Cooperation and Development (OECD) # 203 recommended semi-static renewal bioassay. The assessment was necessary for the uncontrollable disposal of Neatex (liquid detergent) and Norust CR 486 (corrosion inhibitor) into the Niger Delta environment of Nigeria. The estimated 96-h LC(50) for 7-, 14- and 28-day-old fish in Norust CR 486 exposure was considered "more toxic" than Neatex in all life stages and was dependent on species age, exposure duration and environment. In the fresh water test, for Neatex and Norust CR 486 exposures for day 7, 14 and 28, the 96-h LC50 were 8.79, 17.10 and 82.42 mg/l and 5.55, 13.58 and 20.21 mg/l, respectively. In the brackish test, 15.42 and 46.52 mg/l, not determined (ND) and 7.35, 13.95 and 24.50mg/l were obtained. Differential toxicity was observed in the fresh and brackish water fish for the two chemicals and controls at p<0.05. The high sensitivity of the 7-day-old test organisms to both chemicals provides a rationale for regulatory surveillance and monitoring of both chemicals in the fragile Niger Delta environment.
Journal of Hazardous Materials 08/2008; 157(1):64-8. · 4.17 Impact Factor
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ABSTRACT: The assessment of water and sediment quality from chemical pollutants in the Nigerian Niger Delta were conducted using bioindicators
(Desmoscaris tripsinosa and Palaemonetes africanus). The Organization for Economic Cooperation and Development (OECD) (2004), No.218 direct sediment toxicity assessment was
employed. Shrimp were exposed to sediments treated with Neatex (liquid detergent) and Norust CR 486 (corrosion inhibitor)
at concentrations of 31.25, 62.5, 125, 250 and 500mg/kg. Percentage mortality was measured as the ecological endpoint. Mean
% mortality and estimated lethal concentration LC50values varied with species type, concentration and exposure duration.
Observed % mean mortality of the test organisms in both chemicals were significantly different from that of the control test
suggesting that mortality may be induced by the effect of the chemicals. LC50s were significantly different for both chemicals
at p<0.05, t=6.06 (fresh water) and p<0.05, t=12.34 (brackish). The values from this study are an indication that the chemicals have the potential to cause acute lethal
toxicity. It is a prediction of likely adverse effects on shrimp populations in benthic sediment of the Niger Delta ecological
zone. Consequently, there is a great need to protect some of the more sensitive invertebrates representing the major proportion
of the diet of many other species.
Journal of Surfactants and Detergents 11/2007; 10(4):301-308. · 1.54 Impact Factor
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ABSTRACT: The common cichlid (Tilapia guineensis) of the Niger Delta was exposed to lethal (6.25, 12.5, 25.0, 50.0, and 100 mg l−1) and sublethal (1.56 and 3.13 mg l−1) concentrations of Neatex and Norust CR 486 for four and twenty eight days, respectively. The rate of mortality, level of glycogen reserves in the muscle tissues, and bioaccumulation of surfactants were measured as the ecotoxicological end-point. Estimated 96-h LC50 values were 82.42 mg l−1 (Neatex) and 20.21 mg l−1 (Norust CR 486), indicating that Norust CR 486 was more toxic. The levels of glycogen reserves in muscle tissues decreased significantly (P<0.05) in fish exposed to sublethal concentrations of the chemicals compared with the levels in the control groups. The decreases in glycogen levels in the muscle tissues in the highest concentrations (3.13 mg l−1) were 67% (Neatex) and 75% (Norust CR 486). The percentage reduction correlated with the increase in concentrations of chemicals and exposure duration. Surfactant bioaccumulation in the gill, gut and muscle tissues of fish increased significantly with increasing concentrations. The absence of mortality and surfactant accumulation in the control group may be an indication that the observed effects on the exposed fish may have been due to the chemicals. This study demonstrates the lethal and sublethal effects of surfactant-containing industrial chemicals on mortality and muscle glycogen in Tilapia guineensis.
Chemistry and Ecology 10/2007; 23(5):373-382. · 0.62 Impact Factor
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ABSTRACT: The effects of endosulfan, a widely used organochlorine pesticide in the Niger-Delta ecological zone were examined on cortisol secretion, glutathione S-transferase and acetylcholinesterase enzymatic activities in the serum of a dominant fresh water fish species, Clarias gariepinus. Juveniles stage of C. gariepinus were used for the toxicity study. Lethal concentration of 50% mortality of sample (LC50) was determined using semi-static method. From the result of the LC50 determination lower concentrations of endosulfan were prepared for sub-lethal test. Ten fish per test concentration in three replicates were exposed to varying concentrations of endosulfan (0.00, 0.0025, 0.005, 0.0075 and 0.01) μg/L. Signs of stress and mortality were monitored during the experimental duration. Cortisol levels, GST and AChE activities were measured spectrophotometrically. No visible changes in behaviour and appearance were observed in the treated fishes and no mortality recorded. Significant (p < 0.05) declined in cortisol secretion was observed and the change in the concentration was dose and time dependent. Glutathione S-transferase activity was significantly (p < 0.05) higher than the control and the concentrations increase with increased in concentration and exposure duration. No clear trend was observed in acetylcholinesterase activity. The findings showed that the cortisol levels and GST activity of test organism were affected by the test chemical and therefore could be considered as a suitable marker to evaluate the effect of organochlorine pesticide on fish and other aquatic organisms.
Food and Chemical Toxicology.
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ABSTRACT: Toxicity of basudin (an organophosphate pesticide) on the larval stages of the dominant amphibian; Ptychadena bibroni of the Niger Delta ecological zone of Nigeria was assessed using acute and chronic toxicity in the laboratory. Mortality and body glycogen levels were used as ecological endpoints. The American society of testing and material (ASTM) recommended semi-static renewal bioassay was employed and LC50 was measured at 96 h. The amphibian larval stages were exposed to basudin concentrations of 0.1, 1.0, 10.0 and 25 ug/l. Derived 96 h LC50 values decreased with increased exposure duration. Estimated 96 h LC50 was 0.860 ug/l. Substantial mortality and incidence of abnormal avoidance response occurred more at higher concentrations. Body glycogen levels in all test concentrations were significantly different between the test and the control experiments at P<0.05. The decrease in glycogen level varied negatively with mortality, exposure duration and concentrations. The amphibian assay described in this study can be used to assess the toxicity of basudin pesticides in the course of regulatory surveillance and monitoring of the waters of the Niger Delta ecological zones of Nigeria.
African Journal of Biotechnology (ISSN: 1684-5315) Vol 6 Num 13.
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ABSTRACT: The toxic effects of industrial chemicals on three early life stages of an economically important fish, Tilapia guineensis were investigated using the Organisation for Economic Cooperation and Development (OECD) # 203 recommended semi-static renewal bioassay. The assessment was necessary for the uncontrollable disposal of Neatex (liquid detergent) and Norust CR 486 (corrosion inhibitor) into the Niger Delta environment of Nigeria. The estimated 96-h LC50 for 7-, 14- and 28-day-old fish in Norust CR 486 exposure was considered “more toxic” than Neatex in all life stages and was dependent on species age, exposure duration and environment. In the fresh water test, for Neatex and Norust CR 486 exposures for day 7, 14 and 28, the 96-h LC50 were 8.79, 17.10 and 82.42 mg/l and 5.55, 13.58 and 20.21 mg/l, respectively. In the brackish test, 15.42 and 46.52 mg/l, not determined (ND) and 7.35, 13.95 and 24.50 mg/l were obtained. Differential toxicity was observed in the fresh and brackish water fish for the two chemicals and controls at p < 0.05. The high sensitivity of the 7-day-old test organisms to both chemicals provides a rationale for regulatory surveillance and monitoring of both chemicals in the fragile Niger Delta environment.
Journal of Hazardous Materials.
