1. Katherine von Stackelberg, ScD E Risk Sciences, LLP kvon@erisksciences.com Bioaccumulation and Potential Risk from Sediment- Associated Contaminants in Dredged Materials

2. Risk depends on exposure and toxicity There is no zero- risk option Population variability in response Uncertainty –Exposure concentrations –System dynamics Integration with other analyses Different approaches available Bioaccumulation vs. Risk Years Risk A B B-A=Risk Reduction Benefit MNR Dredging Option A

3. TrophicTrace/BRAMS –“Screening” tool –Rapid evaluation of bioaccumulation potential –Steady state model –http://el.erdc.usace.army.mil/t rophictrace/http://el.erdc.usace.army.mil/t rophictrace/ FishRand-Migration –Greater complexity –Incorporates spatial and temporal aspects of aquatic biota exposure –Probabilistic, time-varying Tiered Approaches to Bioaccumulation Modeling

4. Not Just a Single Number

5. Importance of Characterizing Uncertainty

6. Exposure Characterization in Bioaccumulation Models Bioaccumulation models do not represent fish behavior, foraging strategy, life history, habitat preferences Exposures represented by external processing (average, SWAC, etc.) Changes in exposure over time Either exposed or not – doesn’t capture dynamics of fish behavior Don’t consistently capture uncertainty and variability

7. FishRand Modeling Approach Sampling from a population of fish Movements and foraging strategies contribute to the distribution of predicted tissue concentrations Takes advantage of GIS-based data Probabilistic linkages –Decision analytic approaches –Integration with economic and other data

8. Pre-Remedy Selection

9. Post-Remedy Selection MDS Daily Movements Attraction Factor Seasonal Movement Home Range Foraging Area

10. FishRand Application

12. Results for Largemouth Bass

13. Implications for Risk Assessment

14. Linkages to Other Analyses

15. Conclusions Tiered approaches to modeling: “screening” to complex –Balance data availability, resources, objectives Even screening level assessments should quantify uncertainty Important to consider linkages to other analyses Sustainable sediment solutions and complexity of data and analyses require integrative approaches –Watershed scale –Decision analytic frameworks