PARENT SESSION
TA1 - Multiple Stressors
Chair: Norton, Sue1, 1 U.S. Environmental Protection Agency, Washington, DC
8:00 AM to 12:00 PM - Tuesday, 19 November 2002
Room Ballroom G-I
(326) A challenge approach to assess bioaccumulated residue.
Landrum, Peter*,1, Steevens, Jeffery2, Gossiaux, Duane1, McElroy, Michael3, Robinson, Sander3, Begnoche, Linda4, Chernyak, Sergei4, Hickey, James4, 1 Great Lakes Environmental Research Laboratory,NOAA, Ann Arbor, MI, USA2 Waterways Experiment Station, US Army Corps of Engineers, Vicksburg, MS, USA3 Cooperative Institiute for Limnology and Ecosystem Research, University of Michigan, Ann Arbor, MI, USA4 Great Lakes Science Center, US Geological Survey, Ann Arbor, MI, USA
ABSTRACT- A new approach to assess bioaccumulated contaminants is being developed. This challenge approach requires additive toxicity between the challenge chemical and the bioaccumulated residue. To test this, Hyalella azteca were exposed to aqueous concentrations of pyrene and pentachlorobenzene (PCBZ) in different ratios with different exposure durations. The exposures were also performed with the pyrene incorporated into sediment and the challenge applied in aqueous exposure. The observed toxicity of pyrene and PCBZ were not strictly additive on a molar basis. Larger pyrene body residues are necessary to produce mortality than for PCBZ. However, when converted to toxic units (TU), the two compounds were additive over a range of exposure conditions and ratios. The average total TU for the mixtures was 1.16 +/- 0.22 TU for exposure durations ranging from 48 - 320 h. The TU had to be determined on a temporal basis to demonstrate additivity. Deviations from one TU were greatest at short exposure durations, e.g., 48h. Applying this approach to sediment exposures with pyrene in sediment and PCBZ applied in water allows for several potential experimental designs from simultaneous exposure to sequenced exposure. This results in different temporal exposures of the two compounds depending on the experimental design. A more rapid response to PCBZ was observed when the exposure was simultaneous as opposed to sequential. The challenge approach appears promising for a quantitative assessment of bioaccumulated residues.
Key words: hyalella azteca, body residue effects, pyrene, pentachlorobenzene