Bioaccumulation, elimination, and tissue distribution of chlorpyrifos by red hybrid Tilapia in fresh and brackish waters.
Bioaccumulation, degradation, elimination and tissue partitioning of chlorpyrifos (Dursban 25E) was studied under static conditions for 3-4 days, in fresh (FW) and brackish (BW) waters by two methods: in the renewal method, fish were transferred every 24 h to FW or BW aquaria containing 0.05 mg l(-1) of the insecticide; in the spiking method, the original concentration of 0.005 mg l(-1) was spiked every 8 h. Samples of fish and water were collected at regular intervals and residues determined gas chromatographically. In the renewal experiments with 0.05 mg l(-1), bioconcentration reached its peak within 8 h of exposure in FW (1.25 mg l(-1)) and within 1 h in BW (0.95 mg g(-1)); in spiking experiments with 0.005 mg l(-1), these peaks were attained in 48 h in FW (3.8 mg g(-1)) and 8-24 h in BW (1.67 mg g(-1)). Thereafter, the concentrations declined. The concentrations of an unidentified metabolite were generally but not always correlated with that of the parent compound. Upon exposure of contaminated fish to uncontaminated waters, 72% was eliminated within the first 12 h and 4% later in 60 h in FW, and only 23% in 1 h and another 21% in the following 60 h in BW. Concentration of the metabolite was very high during the elimination. In the renewal experiment with 0.05 mg l(-1) of chlorpyrifos, tissue distribution was much higher in FW than in BW, while the reverse was true in spiking experiments with 0.005 mg l(-1) of the chemical. Testis, heart and brain had the highest levels of residues, followed by ovaries and other tissues.
Thomas
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Pest and Pesticide Research Group, Department of Life Sciences, University of the West Indies, Mona, Kingston 7, Jamaica.
Mansingh
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D000818:Animals; D004390:Chlorpyrifos / Q000378:metabolism* / Q000493:pharmacokinetics*; D007306:Insecticides / Q000378:metabolism* / Q000493:pharmacokinetics*; D012965:Sodium Chloride; D017210:Tilapia; D014018:Tissue Distribution; D014867:Water; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000493:pharmacokinetics*
D007306:Insecticides; D014874:Water Pollutants, Chemical; D014867:Water; D012965:Sodium Chloride; D004390:Chlorpyrifos