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 24h 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 8h. Samples of fish and water were collected at regular intervals and residues determined gas chromatographically. In the renewal experiments with 0.05mg l−1, bioconcentration reached its peak within 8h of exposure in FW (1.25 mg l−1) and within 1h 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 wat...