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(49-02) Developing a bioassay approach for assessing the hazard of bioaccumulated residues for benthic organisms using pentachlorobenzene as a challenge compound. Landrum, Peter*,1, Steevens, Jeffery2, Gossiaux, Duane1, McElroy, Michael3, Robinson, Sander3, Chernyak, Sergei4, Begnoche, Linda4, Hickey, James4, 1 Great Lakes Environmental Research Laboratory, NOAA, Ann Arbor, MI2 Waterways Experiment Station, USACOE, Vicksburg, MS3 Cooperative Institute for Limnology and Ecosystem Research, UM, Ann Arbor, MI4 Great Lakes Science Center, USGS, Ann Arbor, MI ABSTRACT- A bioassay approach to assess the potential impact of bioaccumulated residues was proposed by A. Van Wezel several years ago for fish. If an organism bioaccumulated significant residues and was then faced with a challenge compound a reduced body residue of the challenge compound would be required to produce the toxic response compared to naive organisms. This approach also assumed that organic compounds would act additively when exerting toxicity by non-polar narcosis (anesthesia). We present our initial efforts to develop this approach for benthic organisms for the use in evaluating the potential hazard of bioaccumulated residues. Our initial work includes the criteria for selection of the challenge compound, the mode of exposure for benthic organisms to the challenge, and the preliminary data using pentachlorobenzene as our initial challenge compound. The time-dependent toxicity of pentachlorobenzene was determined and the body residue required to produce 50% mortality in Hyalella azteca declined from a value of 3 mmol/kg at 28 h to 0.4 mmol/kg at 570 h. These data were fit to a new damage assessment model to allow prediction of toxic body residues at varying lengths of exposure. The joint action of pentachlorobenzene and pyrene and the sensitivity of the method will also be presented. Key words: Lethal Body Residues, Hyalella azteca, pentachlorobenzene, bioaccumulation risk |
