objectives. Step 4 requires further consideration of fish ELS dosimetry in the context of the 
mechanism of toxicity associated with the PBT risk being assessed. For example, photo- 
activated toxicity of PAHs in larval fish will involve accumulation of the PAHs in specific 
tissues for which UV light activation is possible. 
4. Inter-Ecosystem Extrapolations. 
The research approach for improving inter-ecosystem extrapolations and comparisons of 
bioaccumulation data will involve the development of appropriate data sets for a variety of 
ecosystem classifications and chemical loading scenarios. With this information, 
bioaccumulation models and tools can be tested and evaluated. The emphasis, initially, will be 
on testing the effectiveness of simpler extrapolation techniques. Extrapolations and comparisons 
of data across ecosystems will involve consideration of differences in the sediment-water 
chemical concentration ratios, departure fi’om steady-state distribution of chemical, food web 
depth (number of trophic levels), and food web composition (benthic-pelagic). The results of 
these comparisons will be used to determine the need for more specific and data intensive 
modeling approaches to reduce uncertainty to a level sufficient for accuracy consistent with 
capability to perform probabilistic risk assessments. 
Products 
FY02 Journal article describing the conceptual model for relating risk-based critical residue 
values in fish and wildlife to chemical concentrations in sediment and water (with context of 
risk-based WQC criteria and contaminated sediment based risk assessments). 
FY02 Technical support document and site-specific methods for determination of BAFs 
associated with the methodology for deriving ambient WQC for the protection of human health 
(MED co-authorship with OW and NCEA). 
FY02 Journal article on BSAFs for PCBs, PCDDs, PCDFs, and PAHs associated with the Lake 
Michigan food web and applicability to other ecosystems. 
FY02 Journal article on validation of the BAF methods used for the methodology for deriving 
ambient WQC for the protection of human health. 
FY03 Journal article on BAFs for PCBs, PCDDs, PCDFs, and PAHs associated with the Lake 
Michigan food web and applicability to other ecosystems. 
FY03 Journal article on proof of concept for measurement of rates of metabolism of PCBs, 
PCDDs, and PCDFs from high quality food web data. 
FY04 Journal article on measurement of rates of metabolism of PAHs from high quality food 
web data with toxicokinetic model interpretation. 
FY04 Report on application of site-specific BAFs and models in conjunction with risk 
assessments requiring extrapolations across species, life stages, and effects endpoints. 
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