1. Considerations for Developing Alternative Health Risk Assessment Approaches for Addressing Multiple Chemicals, Exposures and Effects External Review Draft (2006) Introductory Talk Linda K. Teuschler Scientific Peer Review Meeting May 25-26, 2006 Cincinnati, Ohio

2. Authors U.S. EPA, Office of Research and Development, National Center for Environmental Assessment Cincinnati, OH Richard C. Hertzberg (Retired)John C. Lipscomb Glenn E. RiceLinda K. Teuschler U.S. Department of Energy, Argonne National Laboratory, Argonne, IL Margaret MacDonellJames Butler Young-Soo ChangHeidi Hartmann John PetersonKurt Picel Tetra Tech EM, Inc., Dallas, TX Shanna Collie Shannon Garcia Alan JohnsCamarie Perry ENVIRON Corporation, Emeryville, CA Lynne Haroun

3. Considerations for Developing Alternative Health Risk Assessment Approaches for Addressing Multiple Chemicals, Exposures and Effects (2006) Methodology for Multipathway Combustor Emissions (1998) Guidance for Assessing Health Risks of Chemical Mixtures (2000) Guidance on Cumulative Risk of Pesticides (2002) Risk Assessment Guidance for Superfund (1989) Planning & Scoping for Cumulative Risk Assessment (1997) Planning & Scoping Lessons Learned (2002) Framework for Cumulative Risk Assessment (2003) Related EPA Efforts

4. Definitions from EPA’s 2003 Framework for Cumulative Risk Assessment (EPA/630/P-02/001F) Cumulative Risk: The combined risks from aggregate exposures to multiple agents or stressors. Agents or Stressors: May be chemicals, biological or physical agents, or the absence of a necessity such as habitat. Cumulative Risk Assessment: An analysis, characterization, and possible quantification of the combined risks to health or the environment from multiple agents or stressors.

5. Focus of this 2006 “Approaches” Document (EPA/600/R-06/013A) Concepts and methods for potential use in the conduct of cumulative risk assessments (This is NOT a regulatory document and is NOT official EPA guidance.) Combined human health risks for aggregate exposures to multiple chemicals (Does not address biological or physical stressors.) Exposure methods consider multiple pathways, routes, environmental transformations, timeframes. Toxicity methods consider multiple effects, toxicological interactions. Identify existing risk assessment guidance, data and risk information for use in assessing multiple exposures, effects and chemicals

6. Sources, releases Population illness multiple- chemical fate public health data mixtures toxicity multi-route exposures Combined characterization population subgroup features Chemical concentrations Triggers Data Elements Information Gathering & Processing

7. List of Chemicals of Concern Population Profile Chemical Groups By Toxicity Final Cumulative RA Chemical Groups By Media & Time Integrated Chemical Groups OUTPUTS STEPS 1) Identify “Trigger” for CRA 1.3.1 2) Characterize Population based on Trigger 2.1 3) Generate Chemical List 2.2 5) Quantify Exposure for General Population and Subpopulations 3 6) Quantify Dose- Response for Initial Toxicity-Based Chemical Grouping 4 7) Integrate Exposure & Dose Response; Refine Exposure and Toxicity Assessments 3 & 4 8) Conduct Risk Characterization 5 SECTION 4) Identify Links between Chemicals & Subpopulations 2.3 Key Steps in a Cumulative Risk Assessment

8. New & Emerging Approaches Grouping chemicals for risk assessment based on exposure characteristics and toxic endpoints Multiple route combinations of Relative Potency Factors Internal doses to account for multiple route exposures Integration of categorical regression multiple effects modeling with additivity methods Interaction-Based Hazard Index Emphasis on interdependence of toxicity and exposure for assessing risk Considerations for cumulative risk characterization, using Cumulative Hazard Index as an example Cumulative Risk Toolbox (Appendix A) of existing information for use in assessing multiple exposures, effects and chemicals

9. Document Organization: Chapters & Appendices 1Introduction to Cumulative Risk at the U.S. EPA 2Initial Characterization of the Population and Chemicals of Concern 3Cumulative Exposure Assessment 4Cumulative Toxicity Assessment 5Cumulative Risk Characterization 6References 7Glossary Appendix A: Cumulative Risk Toolbox Appendix B: Toxicity Information to Support Groupings

10. History & Next Steps Feb 2001: NCEA began work developing cumulative risk approaches and information through an Interagency Agreement with the Department of Energy Nov. 2004: Superfund Program Office & Regional Internal EPA Review March 2006: External Review Draft released for a 45 Day Public Comment Period. May 2006: Scientific Peer Panel Review June 2006: Final Report from Peer Panel Review 2006: Final Draft to be published following changes made in response to internal EPA, public and panel comments.