TOXICOKINETICS OF HALOGENATED BENZENES IN FISH - LETHAL BODY BURDEN AS A TOXICOLOGICAL END-POINT

The lethal body burden (LBB), the whole-body concentration in millimoles per kilogram at time of death or immobilization, and the LC50 of dihalogenated (F, Cl, Br) benzenes were measured. Except for 1,4-difluorobenzene in guppy (28 mmol kg-1), LBBs varied between 2 and 8 mmol kg-1. The LBBs of the chemicals in guppies were not significantly different from those in fathead minnows. LC50 values varied between 0.54 and 41 mumol L-1 and were inversely related to the octanol/water partition coefficient, K(ow). To estimate the risk of a compound to fish, the LBB requires the exposure concentration in combination with a first-order one-compartment bioaccumulation model. Therefore, the time of death or the time of immobility, and bioconcentration parameters such as the uptake rate constant (k1) and the elimination rate constant (k2), were determined. For both species, k1 values of the chlorinated benzenes were smaller than those of the brominated compounds and k2 values decreased with increasing hydrophobicity. The lipid-normalized bioaccumulation factors (K(L)'s) were linearly related to K(ow).