TRI Relative Risk-Based Environmental Indicators Methodology ERRATA The sorted compilation of toxicity weights for scored TRI chemicals found in Appendix C, Table C-1 has several omissions and errors. Since the toxicity weights for various TRI chemicals are undergoing further review, and modifications of the scores and the addition of new chemicals are likely, the reader should consult the most recent listing of the toxicity weights used in the TRI Environmental Indicators. Please contact the authors to obtain the most recently published listing. TOXICS RELEASE INVENTORY RELATIVE RISK-BASED ENVIRONMENTAL INDICATORS METHODOLOGY Nicolaas W. Bouwes, Ph.D. Steven M. Hassur, Ph.D. Economics, Exposure and Technology Division Office of Pollution Prevention and Toxics U.S. Environmental Protection Agency June 1997 Contractor Support: Abt Associates, Inc. 4800 Montgomery Lane Bethesda, MD 20814 For further information or inquiries, please contact: Nicolaas W. Bouwes, Ph.D. (202) 260-1622 [email protected] or Steven M. Hassur, Ph.D. (202) 260-1735 [email protected] Economics, Exposure and Technology Division (7406) Office of Pollution Prevention and Toxics U.S. Environmental Protection Agency 401 M St., SW Washington, D.C. 20460 iii ACKNOWLEDGMENTS This report is one of several products of the TRI Relative Risk-Based Environmental Indicators Project. This project was initiated in 1991 and is presently being implemented within the Office of Pollution Prevention and Toxics (OPPT). We feel that this unique and powerful analytical tool has the potential to make a significant contribution to environmental improvement. This is very gratifying to us as both scientists and environmentalists. The project has had the good fortune to benefit from the contributions of many highly qualified individuals. In particular, Susan Keane and Brad Firlie of Abt Associates, Incorporated who have provided superior and creative contractor support to the project throughout its entire period of development; and Loren Hall of the Environmental Assistance Division of OPPT, who has provided invaluable insights and direction to the project. Also, we wish to express our thanks to the individuals who served on the Indicators Workgroup that developed the early framework of the methodology. The management team of the Economics, Exposure and Technology Division (EETD) and OPPT are also to be commended for their full support and conviction regarding the importance of this project: Bob Lee, Chief of the Economic and Policy Analysis Branch, has been actively involved in project development and had the foresight to appreciate the potential economic applications of the Indicators; Roger Garrett, former Chief of the Industrial Chemistry Branch (ICB) directly assisted us in formulating our first approach while Russ Farris, Section Chief, and Paul Anastas, Chief of ICB, have provided valuable advice; and Mary Ellen Weber, Director, always found us the support to maintain this project’s momentum and focus. Finally, we wish to recognize Michael Shapiro, Director of the Office of Solid Waste, who as past Director of EETD had the intuition to conceive the basic premise of a national set of indicators reflecting risks associated with TRI emissions. The project management team later developed this concept into the multi-media, relative risk-based approach described here. Project Managers: Nick Bouwes and Steve Hassur Work Group Members Abt Associates Project Staff Nicolaas Bouwes, Chair Susan Egan Keane, Project Manager Steven Hassur Brad Firlie, Deputy Project Manager Loren Hall Lisa Akeson Nancy Beach Amy Benson David Brooks Kathy Cunningham Daniel Bushman Jonathan Kleinman Karen Hammerstrom Michael Müller Sondra Hollister Alexandra Varlay John Leitzke Carol Wagett Patrick Miller Richard Walkling Samuel Sasnett Richard Wells Nestor Tirado Michael Conti (technical reviewer) Sylvon Vonderpool Andrew Wheeler Thanks to these individuals for providing exposure-related support: Bob Boethling David Lynch iv v TABLE OF CONTENTS ACKNOWLEDGMENTS EXECUTIVE SUMMARY ................................................ ES-1 Introduction ....................................................... ES-1 How Indicator Toxicity Weightings Differ from EPCRA Section 313 Statutory Criteria ..................................................... ES-2 Emergency Planning and Community Right-to-Know Act Section 313 Statutory Criteria .................................................. ES-3 Relative Toxicity Weighting of Chemicals in the TRI Relative Risk-Based Chronic Human Health Indicator ..................................... ES-4 General Description of the TRI Relative Risk-based Environmental Indicators ..... ES-4 Methods for Calculating Toxicity Weights ................................ ES-6 Chronic Human Toxicity Weights .................................... ES-6 Chronic Ecological Toxicity Weights ................................. ES-7 Methods for Adjusting Releases and Transfers for Chronic Human Exposure Potential ....................................................... ES-8 Quantitative Data Used in Evaluating Chronic Human Exposure Potential ..... ES-8 Qualitative Data Used in Evaluating Chronic Human Exposure Potential ...... ES-9 Methods to Adjust for Size of Population Exposed ......................... ES-9 Computing the TRI Relative Risk-based Environmental Indicators ............. ES-10 Adjusting the Indicators for Changes in the TRI ........................ ES-11 Generating “Subindicators” ....................................... ES-12 Current Implementation of the TRI Relative Risk-based Environmental Indicators Method ................................................. ES-12 Computer Program to Calculate the Indicators ......................... ES-13 Chemicals and Facilities Currently Included in the Indicators .............. ES-13 Issues for Future Consideration and Conclusions .......................... ES-13 I. INTRODUCTION .................................................... 1 How Indicator Toxicity Weightings Differ from EPCRA Section 313 Statutory Criteria ........................................................... 3 Emergency Planning and Community Right-to-Know Act Section 313 Statutory Criteria ........................................................ 4 Relative Toxicity Weighting of Chemicals in the TRI Relative Risk-Based Chronic Human Health Indicator ........................................... 5 vi II. GENERAL DESCRIPTION OF THE TRI RELATIVE RISK-BASED ENVIRONMENTAL INDICATORS ..................................... 5 Approaches Used to Adjust Releases and Transfers in Other Existing Screening Systems .......................................................... 5 General Approach Used for the TRI Relative Risk-based Environmental Indicators .... 6 III. METHODS FOR CALCULATING TOXICITY WEIGHTS .................. 9 Chronic Toxicity Weights — Human ....................................... 9 Qualitative Data Used in Chronic Human Toxicity Weighting .................. 9 Quantitative Data Used in Chronic Human Toxicity Weighting ................ 12 Types of Data .................................................. 12 Sources of Data ................................................ 12 General Format for Combining Weight-of-Evidence and Slope Factors to Assign Weights ...................................................... 13 The Human Health Toxicity Weighting Schemes .......................... 17 Carcinogenic Effects ............................................. 17 Noncancer Effects .............................................. 19 Selecting the Final Chronic Human Health Toxicity Weight for a Chemical ....... 19 Chronic Toxicity Weights — Ecological .................................... 20 Data Used in Chronic Aquatic Toxicity Weighting ......................... 21 The Aquatic Toxicity Weighting Matrices ................................ 21 IV. METHODS FOR ADJUSTING RELEASES AND TRANSFERS FOR CHRONIC EXPOSURE POTENTIAL ............................................ 23 Evaluating chronic Human Exposure Potential — General Description ............. 23 Quantitative Data Used in Evaluating Chronic Human Exposure Potential ....... 23 Qualitative Data Used in Evaluating Chronic Human Exposure Potential ........ 26 Pathway-specific Methods to Evaluate Chronic Human Exposure Potential ......... 27 GIS Basis Common to All Pathways .................................... 27 Stack and Fugitive Air Releases ....................................... 27 Direct Surface Water Releases ........................................ 33 On-site Land Releases .............................................. 35 Releases to POTWs ................................................ 41 Off-site Transfers .................................................. 43 Evaluating Ecological Exposure Potential — General Strategy for Aquatic Systems ... 49 V. METHODS TO ADJUST FOR SIZE OF POPULATION EXPOSED .......... 49 Estimating Population Size and Representing Rural Populations .................. 49 VI. COMPUTING THE INDICATORS ..................................... 50 Integrating Toxicity, Exposure, and Population Adjustments to Obtain Indicator Elements ........................................................ 50 vii Chronic Human Health Indicator ...................................... 50 Chronic Ecological Indicator ......................................... 51 Combining Elements to Obtain the Overall Indicators .......................... 52 Other Methods of Calculation Considered ............................... 53 Using the indicator