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

The lethal body burden (LBB), the whole-body concentration in millimol es per kilogram at time of death or immobilization, and the LC50 of di halogenated (F, Cl, Br) benzenes were measured. Except for 1,4-difluor obenzene 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 differe nt 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 L BB requires the exposure concentration in combination with a first-ord er one-compartment bioaccumulation model. Therefore, the time of death or the time of immobility, and bioconcentration parameters such as th e uptake rate constant (k1) and the elimination rate constant (k2), we re determined. For both species, k1 values of the chlorinated benzenes were smaller than those of the brominated compounds and k2 values dec reased with increasing hydrophobicity. The lipid-normalized bioaccumul ation factors (K(L)'s) were linearly related to K(ow).