Science and Judgment in Risk Assessment

The public depends on competent risk assessment from the federal government and the scientific community to grapple with the threat of pollution. When risk reports turn out to be overblown?or when risks are overlooked?public skepticism abounds. This comprehensive and readable book explores how the U.S. Environmental Protection Agency (EPA) can improve its risk assessment practices, with a focus on implementation of the 1990 Clean Air Act Amendments. With a wealth of detailed information, pertinent examples, and revealing analysis, the volume explores the "default option" and other basic concepts. It offers two views of EPA operations: The first examines how EPA currently assesses exposure to hazardous air pollutants, evaluates the toxicity of a substance, and characterizes the risk to the public. The second, more holistic, view explores how EPA can improve in several critical areas of risk assessment by focusing on cross-cutting themes and incorporating more scientific judgment. This comprehensive volume will be important to the EPA and other agencies, risk managers, environmental advocates, scientists, faculty, students, and concerned individuals. Table of Contents Front Matter Executive Summary 1 Introduction Part I Current Approaches to Risk Assessment: 2 Risk Assessment and its Social and Regulatory Contexts 3 Exposure Assessment 4 Assessment of Toxicity 5 Risk Characterization Part II Strategies for Improving Risk Assessment: 6 Default Options 7 Models, Methods, and Data 8 Data Needs 9 Uncertainty 10 Variability 11 Aggregation Part III Implementation of Findings: 12 Implementation References Appendix A: Risk Assessment Methodologies: EPA Appendix B: EPA Memorandum from Henry Habicht Appendix C: Calculation and Modeling of Exposure Appendix D: Working Paper for Considering Draft Revisions to the U.S. EPA Guidelines for Cancer Risk Assessment Appendix E: Use of Pharmacokinetics to Extrapolate from Animal Data to Humans Appendix F: Uncertainty Analysis of Health Risk Estimates Appendix G: Improvement in Human Health Risk Assessment Utilizing Site- and Chemical-Specific Information: A Case Study Appendix H-1: Some Definitional Concerns About Variability Appendix H-2: Individual Susceptibility Factors Appendix I: Aggregation Appendix J: A Tiered Modeling Approach for Assessing the Risks Due to Sources of Hazardous Air Pollutants Appendix K: Science Advisory Board Memorandum on the Integrated Risk Information System and EPA Response Appendix L: Development of Data Used in Risk Assessment Appendix M: Charge to the Committee Appendix N-1: The Case for Appendix N-2: Making Full Use of Scientific Information in Risk Assessment Index