UPTAKE AND ELIMINATION OF CHLORPYRIFOS IN THE GUPPY AT SUBLETHAL AND LETHAL AQUEOUS CONCENTRATIONS

Uptake and elimination rate constants of the organophosphorus insecticide chlorpyrifos were determined for the guppy (Poecilia reticulata), employing a first-order, one-compartment model. The constants were found to be 7000 +/1 2000 1 kg-1 d-1 (uptake), and 0.40 +/- 0.11 d-1 (elimination) expressed on the basis of lipid weight. Upon exposure of guppies to time-varying sublethal concentrations of the insecticide for three weeks it was found that the residues observed in fish were in reasonable agreement with predicted values. When, however, exposing guppies to lethal aqueous concentrations the amount of xenobiotic found in fish was higher than calculated using the first-order one-compartment model.