Response spectrum of fluoranthene and pentachlorobenzene for the fathead minnow (Pimephales promelas)

Internal body residue has been recognized as a potential dose metric for toxicological assessments. This relationship between body residue and biological effects, including both lethal and sublethal effects, is critically important for determining environmental quality in risk assessments. The present study identified the toxic equivalent body residues for fluoranthene (FLU) and pentachlorobenzene (PCBz) associated with mortality, reduced growth, and decreased hatchability in the fathead minnow. The toxic equivalent body residue was defined as the total of the parent compound and the organically extractable metabolites for FLU and of the parent compound only for PCBz, because no biotransformation was measurable. The lethal body residues corresponding to 50% mortality were 0.80 and 1.26 micromol/g wet weight for FLU and PCBz, respectively. As expected, residues associated with sublethal effects generally are 2- to 40-fold lower than the lethal residues for FLU and PCBz. Juvenile fish growth was the most sensitive endpoint examined for both compounds. The maximum allowable toxicant residues were 0.02 and 0.43 micromol/g wet weight for FLU and PCBz, respectively. The information collected from the present study will permit a greater understanding of residue-response relationships, which will be useful in risk assessments.