A NOVEL METHOD TO DETERMINE UPTAKE AND ELIMINATION KINETICS OF VOLATILE CHEMICALS IN FISH

The development of an exposure system suitable for studying the uptake and elimination kinetics in fish of volatile chemicals is discussed. Static exposure of the fish is in a closed system containing water and air. Automated sampling and analysis of the air provides a concentrat ion-time profile that is then fit to differential equations using nume rical integration methods. Assumptions for the mathematical descriptio n of the system are a) instantaneous distribution of chemical between water and air, and b) a first order one-compartment model describes th e kinetics of chemical in fish. Uptake and elimination rate constants in fathead minnows (Pimephales promelas) were determined for a mixture of benzene, toluene, monochlorobenzene, monobromobenzene, and 1,3-dic hlorobenzene. No significant biotransformation was observed for any of the compounds. Uptake rate constants increased with increasing octano l-water partition coefficient (K-OW), whereas the elimination rate con stants were inversely related to K-OW. (C) 1998 Elsevier Science Ltd.