Science and judgment in risk assessment / Committee on Risk Assessment of Hazardous Air Pollutants, Board on Environmental Studies and Toxicology, Commission on Life Sciences, National Research Council.

Format:

Book

Contributor:

National Research Council (U.S.). Committee on Risk Assessment of Hazardous Air Pollutants.

Language:

English

Subjects (All):

Air--Pollution--Toxicology--United States--Statistical methods.

Air.

Health risk assessment--Statistical methods.

Health risk assessment.

Physical Description:

1 online resource (667 p.)

Edition:

1st ed.

Place of Publication:

Washington, D.C. : National Academy Press, 1994.

Language Note:

English

Summary:

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.

Contents:

Science and Judgment in Risk Assessment

Copyright

Other Recent Reports Of The Board On Environmental Studies And Toxicology

Preface

Contents

Executive Summary

REGULATION OF HAZARDOUS AIR POLLUTANTS

CHARGE TO THE STUDY COMMITTEE

CURRENT RISK-ASSESSMENT PRACTICES

STRATEGIES FOR RISK ASSESSMENT

Flexibility and the Use of Default Options

Recommendations

Validation: Methods and Models

Priority-Setting and Data Needs

Variability

Uncertainty

Aggregation

Communicating Risk

Recommendation

An Iterative Approach

OVERALL CONCLUSIONS AND RECOMMENDATIONS

1 Introduction

Charge To The Committee

Conceptual Framework Of The Report

Part I Current Approaches to Risk Assessment

2 Risk Assessment and Its Social and Regulatory Contexts

General Concepts

What is Risk Assessment?

How Is Risk Assessment Conducted?

What is the Relationship Between Risk Assessment and Research?

What is the Relationship Between Risk Assessment and Regulatory Decision-Making?

What Is a Default Option?

Historical Roots

Early Efforts to Establish Safe Limits of Exposure to Toxic Substances

The Problem of Carcinogens

NRC Study Of Risk Assessment In The Federal Government

Events After Release Of The 1983 NRC Report

Uses Of Risk Assessment In The Regulation Of Hazardous Air Pollutants

Noncancer Risk Associated With Hazardous Air Pollutants

Public Criticism Of Conduct And Uses Of Risk Assessment

Criticisms Pertaining to Conduct of Risk Assessment

Criticisms Pertaining to the Relationship Between Risk Assessment and Risk Management

Note

3 Exposure Assessment

Introduction

1992 Exposure-Assessment Guidelines.

Exposure Calculation and the Maximally Exposed Individual

Emission Characterization

Sources of Emissions

Emission Estimation Methods

Measurement Methods

Modeling Used In Exposure Assessment

Modeling Airborne Concentrations

Modeling Multimedia Exposure to Air Pollutants

Alternative Transport and Fate Models

Time-Activity Patterns

Exposure-Assessment Models

Long-Term Exposure Modeling

Short-Term Exposure Modeling

4 Assessment of Toxicity

Principles Of Toxicity Assessment

Hazard Identification

Epidemiologic Studies

Animal Studies

Dose-Response Assessment

Toxic Effects Other Than Cancer

Cancer

New Trends In Toxicity Assessment

5 Risk Characterization

Elements Of Risk Characterization

Quantitative Estimates of Risk

Individual Risk

Population Risk

Description of Uncertainty

Superfund Risk-Assessment Guidance

Uncertainty Analysis for Radionuclide Risk

Presentation of Risk Estimates

1992 Exposure-Assessment Guidelines

Risk-Characterization Memorandum

Communication of Risk

Part II Strategies for Improving Risk Assessment

The Need For Risk-Assessment Principles

Reporting Risk Assessments

The Iterative Approach

6 Default Options

Adoption Of Guidelines

Departures From Default Options

Current Epa Practice In Departing From Default options

Example 1: Use of Animal-Cancer Bioassay Data

Example 2: Linkages Between Exposure, Dose, and Response

Methylene Chloride

Formaldehyde

Trichloroethylene

Cadmium

Nickel

Dioxins

Example 3: Modeling Exposure-Response Relationship

Findings And Recommendations

Use of Default Options

Articulation of Defaults

Justification for Defaults

Alternatives to Default Options

Process For Departures

Missing Defaults

7 Models, Methods, and Data.

Introduction

Exposure Assessment

Population

Air-Quality Model Evaluation

Assessment Of Toxicity

Qualitative Considerations

Quantitative Considerations

Carcinogen Classification

Other End Points of Toxicity

Impact of Pharmacokinetic Information in Risk Assessment

Conclusions

Predictive Accuracy and Uncertainty of Models

Guidelines

External Collaboration

Gaussian-Plume Models

Exposure Models

Population Data

Human-Exposure Model

Assessment of Toxicity

Extrapolation from Animal Data for Carcinogens

Extrapolation of Animal Data on Noncarcinogens

Classification of Evidence of Carcinogenicity

Potency Estimates

8 Data Needs

Context Of Data Needs

Implications For Priority-Setting

Data Needed For Risk Assessment

Emissions

Priorities for Collecting Data

Data Availability

Environmental Fate and Transport

Exposure

Toxicity

Overall Priority Setting

Screening risk assessment

Full risk assessment

Data Management

Insufficient Data for Risk Assessment

Need for Data-Gathering Guidelines

Inadequacy of Emission and Exposure Data

Inadequacy of TRI Database as a Source of Emission Data for Risk-Assessment Purposes

Lack of Adequate Natural Background-Exposure Database

Inadequate Explanation of Analytical Techniques

Need for System of Data Management for Risk Assessment

9 Uncertainty

Context Of Uncertainty Analysis

Nature Of Uncertainty

Taxonomies

Problems With EPA's Current Approach To Uncertainty.

Some Alternatives To EPA's Approach

Probability Distributions

Subjective Probability Distributions

Model Uncertainty: "Unconditional" Versus "Conditional" PDFs

Specific Guidance On Uncertainty Analysis

Generating Probability Distributions

Statistical Analysis of Generated Probabilities

Barriers to Quantitative Uncertainty Analysis

Uncertainty Guidelines

Risk Management And Uncertainty Analysis

Single Estimates of Risk

Risk Communication

Comparison, Ranking, And Harmonization Of Risk Assessments

Single Point Estimates and Uncertainty

Comparison of Risk Estimates

Harmonization of Risk Assessment Methods

Ranking of Risk

Notes

10 Variability

Introduction And Background

Exposure Variability

Emissions Variability

Atmospheric Process Variability

Microenvironmental and Personal-Activity Variability

Variability In Human Susceptibility

Overall Susceptibility

Exposure Variability and the Maximally Exposed Individual

Susceptibility

Other Changes in Risk-Assessment Methods

Identifiability and Risk Assessment

Potency

11 Aggregation

Exposure Routes

Risk-Inducing Agents

Types of Nonthreshold Risk

Other Nonthreshold End Points

Genetic Effects

Reproductive/Developmental Risks

Measures And Characteristics Of Risk

Overall Characterization Goals

Consistency in Characterization: Example of Aggregation of Uncertainty

Uncertainty and Variability

Aggregation of Uncertainty and Variability

Multiple Routes of Exposure

Multiple Compounds and End Points

Genetic Effects.

Reproductive and Developmental Toxicants

Upper-Bound Estimates" versus "Best Estimates

Uncertainty versus Variability

Part III Implementation of Findings

12 Implementation

Priority-Setting And Section 112

Iterative Risk Assessment

Summary

Epa Practices: Points To Consider

Implications for Priority-Setting for Title III Activities

Model Evaluation and Data Quality

Default Options

Uncertainty Analysis

Institutional Issues In Risk Assessment And Management

Stability and Change

Management As Guide To Assessment

Comparisons of Risk

Risk Management and Research

Risk Assessment as a Policy Guide

Social and Cultural Factors

Tiered vs. Iterative Risk Assessment

Verification of Amount of Risk-Assessment Conservatism

Full Set of Exposure Models

IRIS Data Quality

Toxicity Data Development

Full Data Set for Priority-Setting

Iterative Priority-Setting

Full and Complete Documentation of Priority-Setting

Guidelines vs. Requirements

Process for Public Review and Comment

Petitions for Departure from Default Options

Iterative Uncertainty Analysis

Risk Assessment vs. Risk Management

Policy Focus on Stationary Sources

References

Appendixes

Appendix A Risk Assessment Methodologies: EPA's Responses to Questions from the National Academy of Sciences

Disclaimer

Table of Contents

Question 1: What Does EPA Consider To Be the Risk Assessment Requirements Needed To Implement the Clean Air Act of 1990?

I.A. Introduction

I.B. Regulatory Flow and Chronology of Title III Implementation

I.C Levels of Risk Assessment

I.D Risk Assessment Review Requirements

I.E Title III Risk-Related Provisions.

II. Question 2: What has EPA done in the past toward those or similar risk assessment requirements, and why did EPA.

Notes:

Bibliographic Level Mode of Issuance: Monograph

Includes bibliographical references and index.

ISBN:

9786610196425

9781280196423

1280196424

9780309556224

0309556228

9780585025216

0585025215

OCLC:

427404692