COVER PAGEEPA/600/6-88/005Cb

DO NOT QUOTE OR CITE

June 1994External Review Draft

 

ESTIMATING EXPOSURE TO DIOXIN-LIKE COMPOUNDS

VOLUME II: Properties, Sources, Occurrence and Background Exposures

 

NOTICE

THIS DOCUMENT IS A PRELIMINARY DRAFT.

It has not been formally released by the U.S. Environmental Protection Agency and should not at this stage be construed to represent Agency policy. It is being circulated for comment on its technical accuracy and policy implications. Exposure Assessment GroupOffice of Health and Environmental AssessmentU.S. Environmental Protection Agency

Washington, D.C.

DISCLAIMER

This document is an external review draft for review purposes only and does not constitute U.S. Environmental Protection Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

CONTENTS

Page

go to 1. INTRODUCTION 1-1
  • 1.1. BACKGROUND 1-1
  • 1.2. TOXICITY EQUIVALENCY FACTORS 1-2
  • 1.3. OVERALL COMMENTS ON THE USE OF THE DIOXIN EXPOSURE DOCUMENT 1-6
  • 1.4. ORGANIZATION OF VOLUME II 1-7
  • REFERENCES FOR CHAPTER 1 1-9
go to 2. PHYSICAL AND CHEMICAL PROPERTIES AND FATE 2-1
  • 2.1. INTRODUCTION 2-1
  • 2.2. GENERAL INFORMATION 2-2
  • 2.3. PHYSICAL/CHEMICAL PROPERTY EVALUATION METHODOLOGY 2-4
  • 2.4. PHYSICAL/CHEMICAL PROPERTIES - CHLORINATED COMPOUNDS 2-7
    • 2.4.1. Water Solubility 2-7
    • 2.4.2. Vapor Pressure 2-13
    • 2.4.3. Henry's Law Constant 2-15
    • 2.4.4. Octanol/Water Partition Coefficient 2-16
    • 2.4.5. Organic Carbon Partition Coefficient 2-18
    • 2.4.6. Photo Quantum Yields 2-19
  • 2.5. PHYSICAL CHEMICAL PROPERTIES - BROMINATED COMPOUNDS 2-20
  • 2.6. ENVIRONMENTAL FATE - CHLORINATED COMPOUNDS 2-21
  • 2.7. ENVIRONMENTAL FATE - BROMINATED COMPOUNDS 2-42
  • REFERENCES FOR CHAPTER 2 2-47
go to 3. SOURCES 3-1
  • 3.1. OVERVIEW OF SOURCES 3-1
  • 3.2. PULP AND PAPER MILLS 3-14
    • 3.2.1. Bleached Chemical Wood Pulp and Paper Mills 3-14
    • 3.2.2. Nonchemical and Nonwood Pulping and Bleaching Mills 3-18
    • 3.2.3. Ongoing Regulatory Investigations 3-19
  • 3.3. PUBLICLY OWNED TREATMENT WORKS (POTWs) 3-20
    • 3.3.1.Sources of CDDs/CDFs 3-20
    • 3.3.2. Releases of CDDs/CDFs 3-22
  • 3.4. CHEMICAL MANUFACTURING AND PROCESSING SOURCES 3-25
    • 3.4.1. Manufacture of Halogenated Organic Chemicals - Overview 3-25
    • 3.4.2. Manufacture of Halogenated Organic Chemicals - Dioxin/Furan Test Rule Data 3-37
    • 3.4.3. Manufacture of Halogenated Organic Chemicals-Pesticide Data Call-In 3-44
    • 3.4.4. Chlorine Production Using Graphite Electrodes 3-56
    • 3.4.5. Petroleum Refining Catalyst Regeneration 3-59
    • 3.4.6. Additional Chemical Manufacturing and Processing Sources 3-62
  • 3.5. MECHANISMS OF FORMATION OF DIOXIN-LIKE COMPOUNDS DURING COMBUSTION OF ORGANIC MATERIALS 3-63
    • 3.5.1. CDD/CDF Contamination in Fuel as a Source of Combustion Stack Emissions 3-64
    • 3.5.2. Formation of CDDs/CDFs from Precursor Compounds 3-67
    • 3.5.3. The de novo Synthesis of CDDs/CDFs During Combustion of Organic Materials 3-75
    • 3.5.4. Theory on the Emission of Polychlorinated Biphenyls 3-91
    • 3.5.5. Evaluation of Naturally Occurring CDD/CDFs by Examination of Sediment Core Data 3-92
    • 3.5.6. Summary of Theories of CDD/CDF Emissions 3-94
  • 3.6. COMBUSTION AND OTHER HIGH TEMPERATURE SOURCES 3-96
    • 3.6.1. Municipal Solid Waste Incineration 3-97
    • 3.6.2. Hazardous Waste Incineration 3-108
    • 3.6.3. Medical Waste Incineration 3-110
    • 3.6.4. Kraft Black Liquor Recovery Boilers 3-118
    • 3.6.5. Sewage Sludge Incineration 3-119
    • 3.6.6. Primary Nonferrous Metal Smelting/Refining 3-121
    • 3.6.7. Secondary Nonferrous Metal Smelting/Refining 3-122
      • 3.6.7.1 Secondary Aluminum Smelters and Refiners 3-122
      • 3.6.7.2 Secondary Copper Smelters and Refiners 3-123
      • 3.6.7.3 Secondary Lead Smelters and Refiners 3-124
    • 3.6.8. Primary Ferrous Metal Smelting/Refining 3-126
    • 3.6.9. Secondary Ferrous Metal Smelting/Refining 3-127
    • 3.6.10. Scrap Electric Wire Recovery 3-128
    • 3.6.11. Drum and Barrel Reclamation and Incineration 3-129
    • 3.6.12. Tire Combustion 3-131
    • 3.6.13. Motor Vehicle Fuel Combustion 3-132
    • 3.6.14. Wood Burning at Residences 3-141
    • 3.6.15. Industrial Wood-Burning Facilities 3-145
    • 3.6.16. Wood Burned in Forest Fires 3-146
    • 3.6.17. Coal Combustion 3-150
    • 3.6.18. Combustion of Polychlorinated Biphenyls (PCBs) 3-151
    • 3.6.19. Pyrolysis of Brominated Flame Retardants 3-152
    • 3.6.20. Carbon Reactivation Furnaces 3-153
    • 3.6.21. Cement Kilns 3-155
    • 3.6.22. Additional Combustion and High Temperature Sources 3-164
  • 3.7. RESERVOIR SOURCES 3-164
  • 3.8. COMPARING SOURCE EMISSIONS TO DEPOSITION ESTIMATES 3-166
  • REFERENCES FOR CHAPTER 3 3-169
go to 4. LEVELS OF CDD, CDF, AND PCB CONGENERS IN ENVIRONMENTAL MEDIA AND FOOD 4-1
  • 4.1. INTRODUCTION 4-1
  • 4.2. CONCENTRATIONS IN SOIL 4-2
  • 4.3. CONCENTRATIONS IN WATER 4-6
  • 4.4. CONCENTRATIONS IN SEDIMENT 4-8
  • 4.5. CONCENTRATIONS IN FISH AND SHELLFISH 4-13
  • 4.6. CONCENTRATIONS IN FOOD PRODUCTS 4-22
    • 4.6.1. Migration of CDD/CDF from Paper Packaging Into Food 4-23
    • 4.6.2. U.S. Food 4-25
    • 4.6.3 European Food 4-38
    • 4.6.4 Canadian Food 4-41
  • 4.7. CONCENTRATIONS IN AIR 4-41
  • 4.8. TEMPORAL TRENDS 4-48
  • 4.9. SUMMARY OF CDD/CDF LEVELS IN ENVIRONMENTAL MEDIA AND FOOD 4-50
  • 4.10. MECHANISMS FOR ENTRY OF CDD/CDFS INTO THE FOOD CHAIN 4-57
  • REFERENCES FOR CHAPTER 4 4-60
go to 5. BACKGROUND EXPOSURES TO CDD, CDF, AND PCB CONGENERS 5-1
  • 5.1. INTRODUCTION 5-1
  • 5.2. PREVIOUS ASSESSMENTS OF BACKGROUND EXPOSURES 5-1
  • 5.3. UPDATED ASSESSMENT OF BACKGROUND EXPOSURES 5-8
    • 5.3.1. North American Exposures 5-12
    • 5.3.2. Comparison of Previous North American Studies to This Study 5-12
    • 5.3.3. Comparison of Previous European Studies to this Study 5-15
  • 5.4. ASSESSMENT OF BACKGROUND EXPOSURES ON THE BASIS OF BODY BURDEN DATA 5-18
    • 5.4.1. Human Adipose Tissue and Blood Data 5-18
    • 5.4.2. Dermal Exposure 5-27
  • 5.5. HIGHLY EXPOSED POPULATIONS 5-28
    • 5.5.1. Nursing Infants 5-29
    • 5.5.2 Subsistence Fishers 5-33
    • 5.5.3. Subsistence Farmers 5-34
  • REFERENCES FOR CHAPTER 5 5-35
go to 6. PHARMACOKINETICS 6-1
  • 6.1. INTRODUCTION 6-1
  • 6.2. DAILY BACKGROUND LEVELS 6-2
  • 6.3. COMPARTMENTAL MODELING 6-14
    • 6.3.1. Pharmacokinetic Model 6-14
    • 6.3.2. Model Utilization 6-17
    • 6.3.3. Determining Liver Concentrations from Fat Levels 6-20
  • 6.4. INTAKES THROUGH DAILY EXPOSURE 6-25
    • 6.4.1. Determination of Daily Intake Dose from Exposure Concentrations 6-25
    • 6.4.2. Dose Through Lactation 6-26
  • REFERENCES FOR CHAPTER 6 6-36
go to APPENDIX return
go to

appendix A:

ENVIRONMENTAL CHEMISTRY A-1
go to appendix B: ENVIRONMENTAL CONCENTRATIONS B-1
go to appendix C: BIOAVAILABILITY OF DIOXINS C-1
go to TABLES return
go to TABLES 1  
go to table Table 1-1 Toxicity Equivalency Factors (TEF) for CDDs and CDFs 1-3
go to table Table 1-2 Dioxin-Like PCBs 1-4
go to table Table 1-3 Nomenclature for Dioxin-Like Compounds 1-5
go to TABLES 2  
go to table Table 2-1 Possible Number of Positional CDD (or BDD) and CDF (or BDF) Congeners 2-3
go to table Table 2-2 Ranking Scheme for P-Chem Property Evaluation 2-6
go to table Table 2-3 P-Chem Properties for the Dioxin-Like Congeners 2-8
go to table Table 2-4 Vapor-to-Particle-Bound Ratio (V/P) for CDDs and CDFs in Ambient Air: Monitoring Results & Modeling Estimates 2-23
go to table Table 2-5 Rain Scavenging Ratios (W) and Percent Washout Due to Particulates (%P) for CDDs and CDFs in Bloomington and Indianapolis Ambient Air 2-25
go to TABLES 3  
go to table Table 3-1 CDD and CDF Air Emission Estimates for West Germany, Austria, United Kingdom, Netherlands, Switzerland, and the United States 3-7
go to table Table 3-2 Current CDD and CDF Emission Estimates for the United States 3-9
go to table Table 3-3 Confidence Rating Scheme for U.S. Emission Estimates 3-13
go to table Table 3-4 Summary of Bleached Chemical Pulp and Paper Mill Discharges of 2,3,7,8-TCDD and 2,3,7,8-TCDF 3-17
go to table Table 3-5 Quantity of Sewage Sludge Disposed Annually by Primary, Secondary, or Advanced Treatment POTWs and Potential Dioxin TEQ Releases 3-24
go to table Table 3-6 Concentration Ranges of CDD/CDF Homologue Groups in Chlorophenolsa (ppm) 3-27
go to table Table 3-7 Summary of Specific Dioxin-Containing Wastes That Must Comply with Land Disposal Retrictions 3-29
go to table Table 3-8 CDD/CDF Concentrations in Chlorobenzenes (µg/kg) 3-32
go to table Table 3-9 CDD/CDF Levels (µg/kg) in Dioxazine Dyes and Pigments 3-36
go to table Table 3-10 Chemicals Requiring TSCA Section 4 Testing Under the Dioxin/Furan Rule 3-39
go to table Table 3-11 Congeners and Limits of Quantitation (LOQ) for Which Quantitation is Required Under the Dioxin/Furan Test Rule and Pesticide Data Call-In 3-40
go to table Table 3-12 Precursor Chemicals Subject to Reporting Requirements Under TSCA Section 8(a) 3-41
go to table Table 3-13 Results of Analytical Testing for Dioxins and Furans in the Chemicals Tested To-Date Under Section 4 of the Dioxin/Furan Test Rule 3-42
go to table Table 3-14 CDDs and CDFs in Chloranil and Carbazole Violet Samples Analyzed Pursuant to the EPA Dioxin/Furan Test Rule 3-43
go to table Table 3-15 Pesticides That Could Become Contaminated With Dioxins If Synthesized Under Conditions Which Favor Dioxin Formation 3-46
go to table Table 3-16 Pesticides That Are Suspected To Be Contaminated With Dioxins 3-52
go to table Table 3-17 Summary of Analytical Data Submitted to-Date in Response to Pesticide Data Call-In 3-57
go to table Table 3-18 Summary of Results for CDDs and CDFs in Technical 2,4-D Herbicides 3-58
go to table Table 3-19 CDDs/CDFs in Petroleum Refinery Stack Gas from a Continuous Regenerator Without Scrubber 3-60
go to table Table 3-20 CDDs/CDFs in the Scrubber Wash Water from a Petroleum Refinery Periodic/Cyclic Regenerator 3-61
go to table Table 3-21 Concentration of CDDs/CDFs on Municipal Incinerator Fly Ash at Varying Temperatures 3-70
go to table Table 3-22 CDDs/CDFs Formed From the Thermolytic Reaction of 690 mg Benzene + FeCl3Silica Complex 3-76
go to table Table 3-23 De Novo Formation of CDDs/CDFs After Annealing Mg-Al Silicate, 4% Charcoal, 7% Cl, 1% CuCl2.2H2O at 300° C 3-78
go to table Table 3-24 De Novo Formation of Chlorinated Benzenes (CBzs), Polychlorinated Naphthalenes (PCNs), and Polychlorinated Biphenyls (PCBs) after Annealing Mg-Al Silicate, 4% Charcoal, 7% Cl, 1% CuCl2.2H2O 3-79
go to table Table 3-25 CDDs/CDFs Formed from the Combustion of Vegetable Extracts in the Presence of Chlorine Gas 3-86
go to table Table 3-26 CDDs/CDFs Formed from the Combustion of Coal in the Presence of NaCl, Cl2, or Hydrochloric Acid 3-90
go to table Table 3-27 Estimated Number of Operating MSWI Facilities in the United States by Design Category and Type of Air Pollution Control Device 3-101
go to table Table 3-28 Estimated MSW Incineration Emission Factors (EF) and Annual Emissions of Total CDD/CDFs 3-102
go to table Table 3-29 Estimated Number and Type of Facilities and Quantities of Medical Waste Generated Annually in the United States 3-112
go to table Table 3-30 Medical Waste Incineration Facilities Operating in the United States 3-113
go to table Table 3-31 CDD/CDF Emission Factors for Controlled-Air Medical Waste Incinerators Operating in the United States 3-115
go to table Table 3-32 Estimated Annual Emission of Total CDD/CDFs (g/yr) from Incineration of Medical Waste 3-116
go to table Table 3-33 Descriptions and Results of Vehicle Emission Testing Studies for CDDs and CDFs 3-134
go to table Table 3-34 Average Concentrations (ppt) of TCDDs in Chimney Soot from Residential Wood-Burning Stoves in the U.S. 3-143
go to table Table 3-35 Concentrations of Total CDD/CDFs and Dioxin TEQ (grams/dscm) Measured at the Stack of Portland Cement Kilns Burning and Not Burning Hazardous Waste As Supplemental Fuel 3-158
go to TABLES 4  
go to table Table 4-1 Background Data from the National Bioaccumulation Study 4-15
go to table Table 4-2 Summary of Dioxin/Furan Data Collected in the California State Air Resources Board Study 4-29
go to table Table 4-3 Summary of U.S. Food Data from NCASI Study 4-30
go to table Table 4-4 Summary of Schecter et al. (1993) Data on U.S. Foods 4-31
go to table Table 4-5 Summary of CDD/CDF Levels in U.S. Food (pg/g Fresh Weight) 4-37
go to table Table 4-6 CDD/CDF Levels in German Food 4-39
go to table Table 4-7 CDD/CDF Background Levels in Some European, Canadian, and New Zealand Food 4-40
go to table Table 4-8 Concentrations of Dioxins & Furans 4-42
go to table Table 4-9 Maximum CDD/CDF Levels in Foods Collected in Canada (pg/g fresh weight) as Reported by Birmingham et al. (1989) 4-43
go to table Table 4-10 Estimated National Average Concentrations of Dioxins and Furans from the 1982 and 1987 NHATS 4-51
go to table Table 4-11 Summary of CDD/CDF Levels in Environmental Media and Food (whole weight basis) 4-53
go to table Table 4-12 CDD/CDF Congeners that Contribute the Highest Percentage of TEQ to the Total TEQ for All Congeners Combined 4-54
go to TABLES 5  
go to table Table 5-1 Predicted Average Daily Intake of 2,3,7,8-TCDD by the General Population of the United States. 5-3
go to table Table 5-2 Predicted Average Daily Intake of 2,3,7,8-TCDD from Foods by the General Population of the United States. 5-5
go to table Table 5-3 Daily Exposure to 2,3,7,8-TCDD and TEQ from Air, Soil, Food, and Nonfood in The Netherlands 5-6
go to table Table 5-4 Estimated Lifetime Average Daily Exposure of Canadians to Dioxin TEQ 5-7
go to table Table 5-5 Estimated Background Exposures in the United States. 5-9
go to table Table 5-6 Background Exposures via Consumption of German Food 5-11
go to table Table 5-7 Comparison of Predicted Average Daily Intake of 2,3,7,8-TCDD and Total CDD/CDF TEQs 5-16
go to table Table 5-8 NHATS Mean Adipose Tissue Data 5-20
go to table Table 5-9 Human Adipose Tissue Data 5-21
go to table Table 5-10 Mean Levels in Human Serum (ppt) 5-23
go to table Table 5-11 CDD/CDF Levels in Human Blood from Various Countries 5-24
go to table Table 5-12 Dioxin Levels in Human Adipose Tissues from Various Countries 5-25
go to TABLES 6  
go to table Table 6-1 Calculated Daily Intakes for 2,3,7,8-TCDD 6-9
go to table Table 6-2 Half-life Calculations 6-13
go to table Table 6-3 Model-Determined Daily Intakes 6-22
go to FIGURES return
go to FIGURES 3  
go to table Figure 3-1 Estimated TEQ Emissions to Air in the United States. 3-11
go to table Figure 3-2 The Association Between Vapor Phase C12 and the Formation of CDDs/CDFs 3-73
go to table Figure 3-3 The de novo Synthesis of CDD/CDFs from Heating Carbon Particulate at 300° C at Varying Retention Times 3-81
go to table Figure 3-4 Relationship Between Temperature and the de novo Formation of CDDsCDFs 3-82
go to FIGURES 4  
go to table Figure 4-1 Background Environmental Levels in TEQ 4-55
go to FIGURES 5  
go to table Figure 5-1 Background TEQ Exposure for North America by Pathway 5-13
go to table Figure 5-2 Percent Contribution of Various Media to 2,3,7,8-TCDD Exposure in North America 5-14
go to table Figure 5-3 Comparison of Background TEQ Exposures 5-17
go to FIGURES 6  
go to table Figure 6-1 Sample Calculation of Daily Intake for 2,3,7,8-TCDD 6-7
go to table Figure 6-2 Model Estimates of Elimination of 2,3,7,8-TCDD from Fat 6-18
go to table Figure 6-3 Accumulation of TCDD in Fat with 0.44 pg/kg/day dose - Human 6-19
go to table Figure 6-4 Accumulation of TCDD in Fat with 0.30 pg/kg/day dose - Human 6-21
go to table Figure 6-5 Combined Exposure Adipose Tissue Concentration 6-31
go to table Figure 6-6 Background Exposure Adipose Tissue Concentration 6-32
go to table Figure 6-7 Concentration After Lactational Exposure Only 6-33
FOREWORD return

The Exposure Assessment Group (EAG) within the Office of Health and Environmental Assessment of EPA's Office of Research and Development has three main functions:

(1) to conduct exposure assessments,
(2) to review assessments and related documents, and
(3) to develop guidelines for exposure assessments. The activities under each of these functions are supported by and respond to the needs of the various EPA program offices.

In relation to the third function, EAG sponsors projects aimed at developing or refining techniques used in exposure assessments.The purpose of this document is to present and evaluate information on the properties, sources, environmental levels and background exposures to dioxin-like compounds. It is the second in a three volume set addressing these compounds.

The first volume provides an overall executive summary and the third volume presents methods for assessing site-specific assessments of exposure to these compounds. The three volume set serves as a final version of the 1988 draft document titled "Estimating Exposure to 2,3,7,8-TCDD." This effort represents a substantial expansion in scope to include all compounds that exhibit dioxin-like toxicity.

The document is intended to be used as a companion to the health reassessment of dioxin-like compounds that the Agency is publishing concurrently. It is hoped that these documents will improve the accuracy and validity of risk assessments involving this important family of compounds. Michael A. Callahan Director
Exposure Assessment Group

PREFACE return

In April 1991, the U.S. Environmental Protection Agency (EPA) announced that it would conduct a scientific reassessment of the health risks of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and chemically similar compounds collectively known as dioxin.

The EPA has undertaken this task in response to emerging scientific knowledge of the biological, human health, and environmental effects of dioxin. Significant advances have occurred in the scientific understanding of mechanisms of dioxin toxicity, of the carcinogenic and other adverse health effects of dioxin in people, of the pathways to human exposure, and of the toxic effects of dioxin to the environment.In 1985 and 1988, the Agency prepared assessments of the human health risks from environmental exposures to dioxin.

Also, in 1988, a draft exposure document was prepared that presented procedures for conducting site-specific exposure assessments to dioxin-like compounds. These assessments were reviewed by the Agency's Science Advisory Board (SAB). At the time of the 1988 assessments, there was general agreement within the scientific community that there could be a substantial improvement over the existing approach to analyzing dose response, but there was no consensus as to a more biologically defensible methodology. The Agency was asked to explore the development of such a method. The current reassessment activities are in response to this request.The scientific reassessment of dioxin consists of five activities:

1. Update and revision of the health assessment document for dioxin.
2. Laboratory research in support of the dose-response model.
3. Development of a biologically based dose-response model for dioxin.
4. Update and revision of the dioxin exposure assessment document.

5. Research to characterize ecological risks in aquatic ecosystems.

The first four activities have resulted in two draft documents (the health assessment document and exposure document) for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. These companion documents, which form the basis for the Agency's reassessment of dioxin, have been used in the development of the risk characterization chapter that follows the health assessment. The process for developing these documents consisted of three phases which are outlined in later paragraphs. The fifth activity, which is in progress at EPA's Environmental Research Laboratory in Duluth, Minnesota, involves characterizing ecological risks in aquatic ecosystems from exposure to dioxins.

Research efforts are focused on the study of organisms in aquatic food webs to identify the effects of dioxin exposure that are likely to result in significant population impacts. A report titled, Interim Report on Data and Methods for the Assessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) Risks to Aquatic Organisms and Associated Wildlife (EPA/600/R-93/055), was published in April 1993. This report will serve as a background document for assessing dioxin-related ecological risks. Ultimately, these data will support the development of aquatic life criteria which will aid in the implementation of the Clean Water Act.

The EPA had endeavored to make each phase of the current reassessment of dioxin an open and participatory effort. On November 15, 1991, and April 28, 1992, public meetings were held to inform the public of the Agency's plans and activities for the reassessment, to hear and receive public comments and reviews of the proposed plans, and to receive any current, scientifically relevant information.In the Fall of 1992, the Agency convened two peer-review workshops to review draft documents related to EPA's scientific reassessment of the health effects of dioxin. The first workshop was held September 10 and 11, 1992, to review a draft exposure assessment titled, Estimating Exposures to Dioxin-Like Compounds.

The second workshop was held September 22-25, 1992, to review eight chapters of a future draft Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and Related Compounds. Peer-reviewers were also asked to identify issues to be incorporated into the risk characterization, which was under development.In the Fall of 1993, a third peer-review workshop was held on September 7 and 8, 1993, to review a draft of the revised and expanded Epidemiology and Human Data Chapter, which also would be part of the future health assessment document. The revised chapter provided an evaluation of the scientific quality and strength of the epidemiology data in the evaluation of toxic health effects, both cancer and noncancer, from exposure to dioxin, with an emphasis on the specific congener, 2,3,7,8-TCDD.

As mentioned previously, completion of the health assessment and exposure documents involves three phases: Phase 1 involved drafting state-of-the-science chapters and a dose-response model for the health assessment document, expanding the exposure document to address dioxin related compounds, and conducting peer review workshops by panels of experts. This phase has been completed.Phase 2, preparation of the risk characterization, began during the September 1992 workshops with discussions by the peer-review panels and formulation of points to be carried forward into the risk characterization.

Following the September 1993 workshop, this work was completed and was incorporated as Chapter 9 of the draft health assessment document. This phase has been completed.Phase 3 is currently underway. It includes making External Review Drafts of both the health assessment document and the exposure document available for public review and comment.Following the public comment period, the Agency's Science Advisory Board (SAB) will review the draft documents in public session. Assuming that public and SAB comments are positive, the draft documents will be revised, and final documents will be issued.

Estimating Exposures to Dioxin-Like Compounds has been prepared by the Exposure Assessment Group of the Office of Health and Environmental Assessment, Office of Research and Development, which is responsible for the report's scientific accuracy and conclusions. A comprehensive search of the scientific literature for this document varies somewhat by chapter but is, in general, complete through January 1994.

AUTHORS, CONTRIBUTORS, AND REVIEWERS return

The Exposure Assessment Group (EAG) within EPA's Office of Health and Environmental Assessment was responsible for the preparation of this document. General support was provided by Versar Inc. under EPA Contract Numbers 68-D0-0101 and 68-D3-0013. Matthew Lorber of EAG served as the EPA Work Assignment Manager (as well as contributing author) providing overall direction and coordination of the production effort as well as technical assistance and guidance.

AUTHORS

Primary and contributing authors of each chapter are listed below in alphabetical order.

  • Jerry Blancato Chapter 6 U.S. Environmental Protection Agency Las Vegas, NV
  • Elizabeth Brown Chapter 4 Versar, Inc.
  • David Cleverly Chapter 3 U.S. Environmental Protection Agency Washington, DC
  • Jeff Dawson Chapter 3 Versar, Inc.
  • Keith Drewes Chapter 4 Versar, Inc.
  • Carl D'Ruiz Chapter 3 Versar, Inc.
  • Robert Fares Chapter 4 Versar, Inc.
  • Geoffrey Huse Chapters 2, 4, 5 Versar, Inc.
  • Gregory Kew Chapter 3 U.S. Environmental Protection Agency Washington, DC
  • Tim Leighton Chapters 3, 5 Versar, Inc.
  • Matthew Lorber Chapters 3, 4 U.S. Environmental Protection Agency Washington, DC
  • Nica Mostaghim Chapter 4 Versar, Inc.
  • Linda Phillips Chapters 3, 4, 5 Versar, Inc.
  • John L. Schaum Chapters 1 - 5 U.S. Environmental Protection Agency Washington, DC
  • Greg Schweer Chapters 1 - 5 Versar, Inc.

CONTRIBUTORS AND REVIEWERS

An earlier draft of this exposure document was reviewed by the Science Advisory Board in 1988. A revised draft was issued in August 1992 and was reviewed by a panel of experts at a peer-review workshop held September 10 and 11, 1992. Members of the Peer Review Panel for this workshop were as follows:

  • M. Judith Charles, Ph.D. University of North Carolina Chapel Hill, NC
  • Dennis Paustenbach, Ph.D. ChemRisk - A McLaren/Hart Group Alameda, CA
  • Ray Clement, Ph.D. Ontario Ministry of the Environment Quebec, Canada
  • Richard Dennison, Ph.D. Environmental Defense Fund Washington, DC
  • Richard Reitz, Ph.D. Dow Chemical Midland, MI
  • In addition, the following experts outside of EPA have reviewed and/or contributed to this document:
  • Michael Bolger, Ph.D. U.S. Food and Drug Administration Washington, DC
  • James Falco, Ph.D. Battelle, NW Richland, WA
  • Heidelore Fiedler, Ph.D. University of Bayreuth Federal Republic of Germany
  • Charles Fredette Connecticut Dept. of Environmental Protection Hartford, CT
  • George Fries, Ph.D United States Department of Agriculture Beltsville Agricultural Research Center Beltsville, MD
  • Laura Green, Ph.D., DABT Cambridge Environmental, Inc. Cambridge, MA
  • Dale Hattis, Ph.D. Clark University Worcester, MA
  • Steven Hinton, Ph.D., P.E. National Council of the Paper Industry for Air and Stream Improvement Tufts University Medford, MA
  • Kay Jones Zephyr Consulting Seattle, WA
  • George Lew California Air Rrsources Board Sacramento, CA
  • Thomas E. McKone, Ph.D. Lawrence Livermore National Laboratory Livermore, CA
  • Derek Muir, Ph.D Freshwater Institute Department of Fisheries and Oceans Winnipeg, MB, Canada
  • Marvin Norcross, Ph.D. Food Safety Inspection Service, USDA Washington, DC
  • Vlado Ozvacic, Ph.D. Ministry of the Environment Toronto, ON, Canada
  • Thomas Parkerton, Ph.D Manhattan College Riverdale, NY
  • Christopher Rappe, Ph.D. University of Umea Institute of Environmental Chemistry Umea, Sweden
  • Curtis C. Travis, Ph.D. Oak Ridge National Laboratory Oak Ridge, TN
  • Thomas O. Tiernan, Ph.D. Wright State University Dayton, OH
  • Thomas Umbreit, Ph.D. Agency for Toxic Substances and Disease Registry Atlanta, GA
  • G.R. Barrie Webster, Ph.D. University of Manitoba Winnipeg, Canada

The following individuals within EPA have reviewed and/or contributed to this document:

OFFICE

REVIEWERS/CONTRIBUTORS

Office of Research and Development
  • Frank Black
  • Brian Gullett
  • Joel McCrady
  • Philip Cook
  • Donna Schwede
  • Bill Petersen
  • James Kilgroe
Office of Air and Radiation
  • Pam Brodowicz
  • George Streit
  • Thomas Lahre
  • Anne Pope
  • Phil Lorang
  • Walter Stevenson
  • Dennis Pagano J
  • im Crowder
  • Dallas Safriet Joe Somers
  • Joseph Wood
Office of Pollution, Pesticides and Toxic Substances
  • Joe Cotruvo
  • Steven Funk
  • Pat Jennings
  • Leonard Keifer
  • Robert Lipnick
  • Tom Murray
Office of Water
  • Ryan Childs
  • Mark Morris
  • Edward Ohanian
  • Al Rubin
  • Maria Gomez Taylor
Office of General Counsel
  • Chuck Elkins
Office of Policy, Planning and Evaluation
  • Dwain Winters