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Consensus Study Report


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.

Suggested Citation

National Research Council. 1994. Science and Judgment in Risk Assessment. Washington, DC: The National Academies Press.

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Publication Info

672 pages |  6 x 9 |  Paperback
ISBN: 978-0-309-07490-2
Chapters skim
Front Matter i-xvi
Executive Summary 1-15
1 Introduction 16-22
Part I Current Approaches to Risk Assessment: 2 Risk Assessment and its Social and Regulatory Contexts 23-42
3 Exposure Assessment 43-55
4 Assessment of Toxicity 56-67
5 Risk Characterization 68-78
Part II Strategies for Improving Risk Assessment: 6 Default Options 79-105
7 Models, Methods, and Data 106-143
8 Data Needs 144-159
9 Uncertainty 160-187
10 Variability 188-223
11 Aggregation 224-242
Part III Implementation of Findings: 12 Implementation 243-268
References 269-286
Appendix A: Risk Assessment Methodologies: EPA 287-350
Appendix B: EPA Memorandum from Henry Habicht 351-374
Appendix C: Calculation and Modeling of Exposure 375-382
Appendix D: Working Paper for Considering Draft Revisions to the U.S. EPA Guidelines for Cancer Risk Assessment 383-448
Appendix E: Use of Pharmacokinetics to Extrapolate from Animal Data to Humans 449-452
Appendix F: Uncertainty Analysis of Health Risk Estimates 453-478
Appendix G: Improvement in Human Health Risk Assessment Utilizing Site- and Chemical-Specific Information: A Case Study 479-502
Appendix H-1: Some Definitional Concerns About Variability 503-504
Appendix H-2: Individual Susceptibility Factors 505-514
Appendix I: Aggregation 515-536
Appendix J: A Tiered Modeling Approach for Assessing the Risks Due to Sources of Hazardous Air Pollutants 537-582
Appendix K: Science Advisory Board Memorandum on the Integrated Risk Information System and EPA Response 583-590
Appendix L: Development of Data Used in Risk Assessment 591-598
Appendix M: Charge to the Committee 599-600
Appendix N-1: The Case for 601-628
Appendix N-2: Making Full Use of Scientific Information in Risk Assessment 629-640
Index 641-652

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