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SEPA
PUBLIC RELEASE DRAFT
April 2024
EPA Document# EPA-740-D-24-006
April 2024
United States Office of Chemical Safety and
Environmental Protection Agency Pollution Prevention
Draft Risk Evaluation for Asbestos
Part 2: Supplemental Evaluation Including Legacy Uses and
Associated Disposals of Asbestos
CASRN 1332-21-4
April 2024
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS 16
EXECUTIVE SUMMARY 17
1 INTRODUCTION 21
1.1 Scope of the Risk Evaluation 21
1.1.1 Life Cycle and Production Volume 23
1.1.2 Conditions of Use Included in the Risk Evaluation 26
1.1.2.1 Conceptual Models 31
1.1.3 Populations Assessed 36
1.1.3.1 Potentially Exposed or Susceptible Subpopulations 36
1.2 Systematic Review 37
1.3 Organization of the Risk Evaluation 38
2 CHEMISTRY AND FATE AND TRANSPORT OF ASBESTOS 39
2.1 Physical and Chemical Properties 39
2.2 Environmental Fate and Transport 43
2.2.1 Fate and Transport Approach and Methodology 43
2.2.2 Summary of Fate and Transport Assessment 44
2.2.3 Weight of Scientific Evidence Conclusions for Fate and Transport 46
2.2.3.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the Fate and
Transport Assessment 46
3 RELEASES AND CONCENTRATIONS OF ASBESTOS 48
3.1 Approach and Methodology 48
3.1.1 Industrial and Commercial 48
3.1.1.1 General Approach and Methodology for Environmental Releases 49
3.1.2 Take-Home 50
3.1.2.1 Methods and Key Assumptions to Determine Asbestos Concentrations 50
3.1.2.2 Data Sources and the Take-Home Slope Factor Estimation 52
3.1.2.3 Take-Home Scenario Concentration Data Uncertainties and Variability 56
3.1.3 Consumer 57
3.1.3.1 Friable Asbestos Fibers in Products and Products Prioritized for Assessment 58
3.1.3.2 Activity-Based Scenarios and Data Sources 64
3.1.3.3 Concentrations of Asbestos in Activity-Based Scenarios 64
3.1.3.4 Summary of Inhalation Data Supporting the Consumer Exposure Assessment 64
3.1.3.5 Consumer DIY Scenarios Concentration Uncertainties and Variability 68
3.1.4 Indoor Air 69
3.1.4.1 Conclusions for Indoor Air 71
3.2 Environmental Releases 71
3.2.1 Industrial and Commercial 71
3.2.1.1 Summary of Daily Environmental Release Estimates 73
3.2.1.2 Weight of Scientific Evidence Conclusions for Environmental Releases from
Industrial and Commercial Sources 75
3.2.1.2.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
Environmental Release Assessment 75
3.3 Concentrations of Asbestos in the Environment 77
3.3.1 Ambient Air Pathway 77
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85 3.3.1.1 Measured Concentrations in Ambient Air 77
86 3.3.1.2 Modeled Concentrations in Ambient Air 79
87 3.3.1.3 Concentrations of Asbestos in Ambient Air Summary 83
88 3.3.1.4 Ambient Air Concentration Data Uncertainty and Variability 87
89 3,3.2 Water Pathway 88
90 3.3.2.1 Measured Concentrations in Surface and Drinking Water 88
91 3.3.3 Land Pathway 90
92 3.3.4 Modeled Deposition Rates from Environmental Releases 91
93 4 ENVIRONMENTAL RISK ASSESSMENT 93
94 4.1 Environmental Exposures 93
95 4,1.1 Approach and Methodology 93
96 4.1.2 Exposures to Ecological Species 93
97 4.1.3 Weight of Scientific Evidence Conclusions for Environmental Exposures 94
98 4.2 Environmental Hazards 94
99 4,2.1 Approach and Methodology 94
100 4.2.2 Aquatic Species Hazard 95
101 4.2.3 Terrestrial Species Hazard 98
102 4.2.4 Environmental Hazard Thresholds 98
103 4.2.5 Summary of Environmental Hazard Assessment 99
104 4.2.6 Weight of Scientific Evidence Conclusions for Environmental Hazards 100
105 4.2.6.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
106 Environmental Hazard Assessment 100
107 4.3 Environmental Risk Characterization 103
108 4.3.1 Risk Characterization Approach and Summary 103
109 5 HUMAN HEALTH RISK ASSESSMENT 105
110 5.1 Human Exposures 105
111 5.1.1 Occupational Exposures 106
112 5.1.1.1 Approach and Methodol ogy 106
113 5.1.1.1.1 Consideration of Engineering Controls and Personal Protective Equipment 109
114 5.1.1.2 Summary of Inhalation Exposure Assessment 112
115 5.1.1.3 Summary of Dermal and Oral Exposure Assessment 117
116 5.1.1.4 Weight of Scientific Evidence Conclusions for Occupational Exposure 117
117 5.1.1.4.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
118 Occupational Exposure Assessment 119
119 5.1.2 Take-Home Exposures 121
120 5.1.2.1 Concentrations of Asbestos in Take-Home Scenarios 122
121 5.1.2.2 Weight of Scientific Evidence Conclusions for Take-Home 123
122 5.1.2.2.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
123 Take-Home Exposure Assessment 124
124 5.1.3 Consumer Exposures 125
125 5.1.3.1 Approach and Methodol ogy 125
126 5.1.3.1.1 Consumer COUs and Acitivy-Based Exposure 125
127 5.1.3.1.2 Consumer Exposure and Risk Estimation Approach 125
128 5.1.3.2 Summary of Consumer Activity-Based Scenarios Exposure Concentrations 129
129 5.1.3.3 Weight of Scientific Evidence Conclusions for Consumer Exposure 130
130 5.1.3.3.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
131 Consumer Exposure Assessment 132
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5.1.4 General Population Exposures 134
5.1.4.1 Approach and Methodology 134
5.1.4.2 Summary of General Population Ambient Air Exposure Concentrations 138
5.1.4.3 Weight of Scientific Evidence Conclusions for General Population Exposure 138
5.1.4.3.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
General Population Exposure Assessment 139
5.1.5 Aggregate Exposure Scenarios 139
5.2 Human Health Hazard 140
5.2.1 Dose-Response Considerations: Cancer 144
5.2.1.1 Inhalation Unit Risk for Part 2 148
5.2.1.2 Uncertainties 149
5.2.2 Dose-Response Considerations: Non-cancer 149
5.2.2.1 Point of Departure for Part 2 151
5.2.3 Mode of Action Considerations 152
5.3 Human Health Risk Characterization 153
5.3.1 Risk Characterization Approach 153
5.3.2 Summary of Human Health Risk Characterization 156
5.3.2.1 Summary of Risk Estimates for Workers 156
5.3.2.2 Summary of Risk Estimates for Take-Home 168
5.3.2.3 Summary of Risk Estimates for Consumers 170
5.3.2.4 Summary of Risk Estimates for General Population 173
5.3.3 Risk Characterization for Potentially Exposed or Susceptible Subpopulations 178
5.3.4 Risk Characterization for Aggregate and Sentinel Exposures 180
5.3.5 Overall Confidence and Remaining Uncertainties in Human Health Risk
Characterization 181
5.3.5.1 Occupational Risk Estimates 187
5.3.5.2 Take-Home Risk Estimates 187
5.3.5.3 Consumer DIY Risk Estimates 187
5.3.5.4 General Population Risk Estimates 188
6 UNREASONABLE RISK DETERMINATION 189
6.1 Background 192
6.1.1 Policy Changes Relating to a Single Risk Determination on the Chemical Substance and
Assumption of PPE Use by Workers 192
6.2 Unreasonable Risk to Human Health 193
6.2.1 Unreasonable Risk to Human Health Asbestos Part 2 194
6.2.1.1 Populations and Exposures EPA Assessed to Determine Unreasonable Risk to Human
Health 194
6.2.1.2 Summary of the Unreasonable Risks to Human Health 194
6.2.1.3 Basis for EPA's Determination of Unreasonable Risk to Human Health 195
6.2.1.4 Unreasonable Risk in Occupational Settings 197
6.2.1.5 Unreasonable Risk for Take-Home Exposures 198
6.2.1.6 Unreasonable Risk to Consumers 198
6.2.1.7 Unreasonable Risk to the General Population 199
6.3 Unreasonable Risk for the Environment 199
6.3.1 Unreasonable Risk for the Environment Asbestos Part 2 199
6.4 Additional Information Regarding the Basis for the Unreasonable Risk Determination 199
6.4.1 Additional Information about COUs Characterized Qualitatively 200
REFERENCES 206
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APPENDICES 227
Appendix A ABBREVIATIONS, ACRONYMS, AND SELECT GLOSSARY 227
A. I Abbreviations 227
A.2 Glossary of Select Terms 229
Appendix B REGULATORY AND ASSESSMENT HISTORY 231
B.l Federal Laws and Regulations 231
B,2 State Laws and Regulations 236
B.3 International Laws and Regulations 237
B.4 Assessment History 238
Appendix C LIST OF SUPPLEMENTAL DOCUMENTS 240
Appendix D PHYSICAL AND CHEMICAL PROPERTIES AND FATE AND TRANSPORT
DETAILS 243
D. 1 Physical and Chemical Properties Evidence Integration 243
D.2 Fate and Transport 245
D.2.1 Approach and Methodology 245
D.2.2 Air and Atmosphere 245
D.2.3 Aquatic Environments 246
D.2.3.1 Surface Water 246
D.2.3.2 Sediments 246
D.2.4 Terrestrial Environments 246
D.2.4.1 Soil 246 247
D.2.4.2 Groundwater 247
D.2.4.3 Landfills 247
D.2.4.4 Biosolids 247
D.2.5 Persistence Potential of Asbestos 247
D.2.5.1 Destruction and Removal Efficiency 247
D.2.5.2 Removal in Wastewater Treatment 248
D.2.6 Bioaccumulation Potential of Asbestos 248
Appendix E ENVIRONMENTAL RELEASES AND OCCUPATIONAL
EXPOSURE ASSESSMENT 249
E.l Components of an Occupational Exposure and Release Assessment 249
E.2 Approach and Methodology for Process Descriptions 249
E,3 Approach and Methodology for Number of Sites and Establishments 249
E.4 Environmental Releases Approach and Methodology 251
E.4.1 Approach for Estimating Wastewater Discharges 252
E.4.1.1 Approach for Estimating Wastewater Discharges from NRC 252
E.4.1.2 Approach for Estimating Wastewater Discharges from TRI 253
E.4.2 Approach for Estimating Air Emissions 253
E.4.2.1 Assessment Using TRI and NEI 253
E.4.3 Approach for Estimating Land Disposals 254
E.4.3.1 Assessment Using TRI 254
E.4.3.2 Assessment Using Literature Search Data 254
E.4.4 Approach for Estimating Number of Release Days 255
E.5 Occupational Exposure Approach and Methodology 255
E.5.1 Worker Activities 256
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E.5.2 Number of Workers and Occupational Non-users 256
E.5.3 Inhalation Exposure Monitoring 257
E.5.4 Average Daily Concentration and Risk Estimation Calculations 260
E.5.4.1 Average Daily Concentration Calculations 260
E.5.4.2 Margin of Exposure and Excess Lifetime Cancer Risk Calculations 263
E.6 Consideration of Engineering Controls and Personal Protective Equipment 266
E.6.1 Respiratory Protection 266
E.7 Evidence Integration for Environmental Releases and Occupational Exposures 268
E.8 Weight of Scientific Evidence Ratings for Environmental Release Estimates by OES 269
E.9 Weight of Scientific Evidence Ratings for Inhalation Exposure Estimates by OES 272
E, 10 Handling Asbestos-Containing Building Materials during Maintenance, Renovation, and
Demolition Activities 275
E.10.1 Process Description 275
E.10.2 Facility Estimates 279
E.10.3 Release Assessment 280
E.10.3.1 Environmental Release Points 280
E.10.3.2 Environmental Release Assessment Results 280
E.10.4 Occupational Exposure Assessment 282
E.10.4.1 Worker Activities 282
E. 10.4.2 Number of Workers and Occupational Non-users 283
E. 10.4.3 Occupational Exposure Results 285
E. 11 Handling Asbestos-Containing Building Materials during Firefighting or Other Disaster
Response Activities 287
E. 11.1 Process Description 287
E.11.2 Facility Estimates 287
E. 11.3 Release Assessment 288
E.l 1.3.1 Environmental Release Points 288
E.l 1.3.2 Environmental Release Assessment Results 288
E. 11.4 Occupational Exposure Assessment 289
E. 11.4.1 Worker Activities 289
E.l 1.4.2 Number of Workers and Occupational Non-users 289
E.l 1.4.3 Occupational Exposure Result 290
E.l2 Use, Repair, or Removal of Industrial and Commercial Appliances or Machinery Containing
Asbestos 292
E.12.1 Process Description 292
E.12.2 Facility Estimates 293
E.12.3 Release Assessment 293
E. 12.3.1 Environmental Release Points 293
E. 12.3.2 Environmental Release Assessment Results 293
E.12.4 Occupational Exposure Assessment 295
E. 12.4.1 Worker Activities 295
E. 12.4.2 Number of Workers and Occupational Non-users 295
E. 12.4.3 Occupational Exposure Result 295
E. 13 Handling Articles or Formulations that Contain Asbestos 297
E.13.1 Process Description 297
E.13.2 Facility Estimates 298
E.13.3 Release Assessment 298
E.13.3.1 Environmental Release Points 298
E.13.3.2 Environmental Release Assessment Results 298
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E.13.4 Occupational Exposure Assessment
E. 13.4.1 Worker Activities
E. 13.4.2 Number of Workers and Occupational Non-users
E.13.4.3 Occupational Exposure Result
E, 14 Handling of Vermiculite Products for Agriculture and Lab Chemicals
E.14.1 Process Description
E.14.2 Qualitative Assessment
E.15 Industrial Mining of Non-asbestos Commodities
E.15.1 Process Description
E.15.2 Qualitative Assessment
E, 16 Waste Handling, Disposal, and Treatment
E.16.1 Process Description
E.16.2 Facility Estimates
E.16.3 Release Assessment
E.16.3.1 Environmental Release Points
E.16.3.2 Environmental Release Assessment Results
E.16.4 Occupational Exposure Assessment
E.16.4.1 Worker Activities
E. 16.4.2 Number of Workers and Occupational Non-users
E. 16.4.3 Occupational Exposure Result
E, 17 Summary of Occupational Inhalation Exposure Assessment
E. 18 Example of Estimating Number of Workers and Occupational Non-users
Appendix F ENVIRONMENTAL EXPOSURE DETAILS
F. 1 Ambient Air Measured Concentrations
F,2 Ambient Air Modeled Concentrations
F.2.1 Meteorological Data
F.2.2 Urban and Rural Populations
F.2.3 Source Specifications
F.2.4 Temporal Emission Patterns
F.2.5 Emission Rates
F.2.6 Deposition Parameters
F.2.7 Output
F.2.8 Specific Facilities Ambient Air Concentrations
F.2.9 Generic Facilties Ambient Air Concentrations by OES
F.3 Ambient Air Concentrations Summary
F.3.1 Low-End Tendency Ambient Air Concentration Groupings and Summary Tables
F.3.2 Central Tendency Ambient Air Concentration Summary Tables
F.3.3 High-End Tendency Ambient Air Concentration Summary Tables
F.4 Water Path way
F. 4.1 Surface Water
F. 4.2 Drinki ng Water
F. 4.3 Groundwater
F.4.4 Sediment
F.4.5 Wastewater
F.5 Soil
Appendix G ENVIRONMENTAL HAZARD DETAILS
G. I Approach and Methodology
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321 G.2 Hazard Identification 360
322 G.2.1 Weight of Scientific Evidence 360
323 Appendix H CONSUMER EXPOSURE DETAILS 364
324 H.l Concentrations of Asbestos in Activity-Based Scenarios 364
325 H. 1.1 Construction, Paint, Electrical, and Metal Products COU 364
326 H. 1.2 Furnishing, Cleaning, Treatment Care Products COU 368
327 Ft. 1.3 Packaging, Paper, Plastic, Toys, Hobby Products COU 369
328 H. 1.4 Automotive, Fuel, Agriculture, Outdoor Use Products COU 369
329 H. 1.5 Chemical Substances in Products not Described by Other Codes 369
330 H.2 Consumer DIY Exposure Risk Estimate 369
331 Appendix I EPIDEMIOLOGIC COHORTS FOR DOSE-RESPONSE 373
332 Appendix J TAKE-HOME EXPOSURE DETAILS 379
333 J.l Data Used for Take-Home Analysis 379
334 J.2 Take-Home Exposure Concentration Calculations 384
335 J.3 Take-Home Risk Estimates for Other Bystander Populations 385
336 Appendix K DETERMINATION OF LESS-THAN-LIFETIME INHALATION UNIT RISK
337 (IUR) VALUES 387
338 Appendix L GENERAL POPULATION 393
339 Appendix M AGGREGATE ANALYSIS 396
340 Appendix N DRAFT EXISTING CHEMICAL EXPOSURE LIMIT (ECEL) DERIVATION. 403
341 N. 1 ECEL and Other Exposure Limit Calculations 403
342 N.2 Summary of Air Sampling Analytical Methods Identified 404
343
344 LIST OF TABLES
345 Table 1-1. Conditions of Use (Life Cycle, Categories, and Subcategories) and Examples of
346 Items/Applications in the Risk Evaluation for Asbestos 27
347 Table 2-1. Physical and Chemical Properties of Asbestos Fiber Type 41
348 Table 2-2. Environmental Fate Properties of Asbestos 43
349 Table 3-1. Crosswalk of Conditions of Use to Occupational Exposure Scenarios Assessed 48
350 Table 3-2. Asbestos 8-Hour TWA Loading Concentrations and 24-Hour TWA Take-Home
351 Concentrations Used in Regression 54
352 Table 3-3. Regression Coefficients for Three Regression Equations 55
353 Table 3-4. Qualitative Assessment of the Uncertainty and Variability Associated with Concentration
354 Data Used in Take-Home Exposure Analysis 57
355 Table 3-5. Conditions of Use, Product Examples, Weight Fractions, and Friable Fibers 59
356 Table 3-6. Summary of Activity-Based Scenario Studies and Exposure Point Concentrations 66
357 Table 3-7. Qualitative Assessment of the Uncertainty and Variability Associated with Concentrations
358 Data Used in Consumer Assessment 69
359 Table 3-8. Summary of Daily Environmental Release Estimates for Asbestos 73
360 Table 3-9. Summary of Published Literature for Measured Ambient Air Concentrations 77
361 Table 3-10. Release Scenarios Considered for Ambient Air and Deposition Modeling 80
362 Table 3-11. Ambient Air Concentration Summary 85
363 Table 3-12. Qualitative Assessment of the Uncertainty and Variability Associated with Concentration
364 Data Used for Ambient Air 87
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Table 3-13. Summary of Measured Surface and Groundwater Concentrations 89
Table 3-14. Soil Concentration Data Sources Description 91
Table 4-1. Aquatic Organisms Environmental Hazard Studies Used for Asbestos 97
Table 4-2. Environmental Hazard Thresholds for Aquatic Environmental Toxicity 100
Table 4-3. Evidence Table Summarizing the Overall Confidence Derived from Hazard Thresholds ... 102
Table 5-1. Assigned Protection Factors for Respirators in OSHA Standard 29 CFR 1910.134 Ill
Table 5-2. Summary of Total Number of Workers and ONUs Potentially Exposed to Asbestos for Each
OES 112
Table 5-3. Summary of Inhalation Exposure Results for Higher-Exposure Potential Workers Based on
Monitoring Data and Exposure Modeling for Each OES 114
Table 5-4. Summary of Inhalation Exposure Results for Lower-Exposure Potential Workers Based on
Monitoring Data and Exposure Modeling for Each OES 115
Table 5-5. Summary of Inhalation Exposure Results for ONUs Based on Monitoring Data and Exposure
Modeling for Each OES 116
Table 5-6. Summary of the Weight of Scientific Evidence for Occupational Exposure Estimates by OES
118
Table 5-7. Data Needs to Obtain Take-Home Yearly Average Concentrations 122
Table 5-8. Estimated CT and HE Yearly Average Concentrations Using Take-Home Slope Factors... 123
Table 5-9. Weight of Scientific Evidence Conclusions for Take-Home Exposure Scenarios 124
Table 5-10. Qualitative Assessment of the Uncertainty and Variability Associated with Concentrations
Data Used in Take-Home Exposure Analysis 125
Table 5-11. Lifetime Cancer Time-Weighting Factors Assumptions for All COUs 127
Table 5-12. Lifetime Cancer Human Exposure Concentrations for Consumer Exposure Activity-Based
Scenarios by COU and Subcategory 129
Table 5-13. Non-cancer Chronic Human Exposure Concentrations for Consumer Exposure Activity-
Based Scenarios by COU and Subcategory 130
Table 5-14. Weight of Scientific Evidence Conclusions for Consumer Exposure Activity-Based
Scenarios 131
Table 5-15. Qualitative Assessment of the Uncertainty and Variability Associated with Consumer Risk
Assessment 133
Table 5-16. Summary of Environmental Releases from Industrial and Commercial Activities for
Inhalation Exposures by OES and Media 134
Table 5-17. General Population Exposure Duration Parameters 137
Table 5-18. Overall Confidence for General Population Exposure Scenarios 139
Table 5-19. Qualitative Assessment of the Uncertainty and Variability Associated with General
Population Assessment 139
Table 5-20. Use Scenarios, Populations of Interest and Toxicological Endpoints Used for Acute and
Chronic Exposures 154
Table 5-21. Occupational Risk Estimates Summary 162
Table 5-22. Take-Home Inhalation Risk Estimates Summary 169
Table 5-23. Consumer Activity-Based Do-It-Yourself Inhalation Risk Estimates Summary 171
Table 5-24. General Population Inhalation of Outside Ambient Air Lifetime Cancer Risk Estimate
Summary 174
Table 5-25. General Population Inhalation of Outside Ambient Air Non-Cancer Chronic Risk Estimate
Summary 176
Table 5-26. Summary of PESS Considerations Incorporated into the Risk Evaluation 179
Table 5-27. Exposure Scenarios Included in Aggregate Analysis 180
Table 5-28. Asbestos Evidence Table Summarizing Overall Confidence for Human Health Lifetime
Cancer and Non-Cancer Chronic Risk Characterization for COUs Resulting in Risks . 182
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Table 6-1. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 1
Occupational COUs) 202
Table 6-2. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 1
Consumer COUs) 203
Table 6-3. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 2
Occupational COUs) 203
Table 6-4. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 2
Consumer DIY COUs) 205
LIST OF FIGURES
Figure 1-1. TSCA Existing Chemical Risk Evaluation Process 21
Figure 1-2. Legacy Asbestos Life Cycle Diagram 25
Figure 1-3. Conceptual Model for Industrial and Commercial Activities and Uses: Potential Exposure
and Hazards 32
Figure 1-4. Asbestos Conceptual Model for Consumer Activities and Uses: Potential Exposures and
Hazards 33
Figure 1-5. Asbestos Conceptual Model for Environmental Releases and Wastes: General Population
Exposures and Hazards 34
Figure 1-6. Asbestos Conceptual Model for Environmental Releases and Wastes: Ecological Exposures
and Hazards 35
Figure 1-7. Exposures and Populations Assessed in this Risk Evaluation 36
Figure 1-8. Diagram of the Systematic Review Process 38
Figure 2-1. Fate and Transport of Asbestos in the Environment 45
Figure 3-1. An Overview of How EPA Estimated Daily Releases for Each OES 50
Figure 3-2. Take-Home Scenario Mechanism of Exposure 51
Figure 3-3. Take-Home Exposure Scenarios Key Assumptions Summary 52
Figure 3-4. Take-Home Exposure Slope Factor Regression for Handler and Bystander 56
Figure 3-5. Specific Facilities Ambient Air Concentrations by Distance from Source for Each OES .... 82
Figure 3-6. Generic Facilities Ambient Air Concentrations by OES for Rural, and Urban Fugitive
Emissions 83
Figure 3-7. Ambient Air Concentration Summary 84
Figure 3-8. Deposition of Asbestos Fibers from Specific Facilities by Distance for Each OES 92
Figure 3-9. Deposition of Asbestos Fibers from Generic Facilities by Distance for Each OES 92
Figure 5-1. Approaches Used for Each Component of the Occupational Assessment for Each OES ... 109
Figure 5-2. Exposure Assessment Approaches Used to Estimate General Population Exposure to
Asbestos 135
Figure 5-3. Modeled Exposure Point Locations for Finite Distance Rings for Ambient Air Modeling
(AERMOD) 137
Figure 5-4. Modeled Ambient Air Concentrations by OES 138
Figure 5-5. Asbestos Aggregate Analysis Approach 140
LIST OF APPENDIX TABLES
Table_Apx B-l. Federal Laws and Regulations 231
Table_Apx B-2. State Laws and Regulations 236
TableApx B-3. Regulatory Actions by Other Governments, Tribes, and International Agreements... 237
Table_Apx B-4. Assessment History of Asbestos 238
TableApx E-l. Summary of EPA's Estimates for the Number of Establishments and Sites for Each
OES 251
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TableApx E-2. Summary of Estimates for Release Days Expected for Each OES 255
TableApx E-3. Data Evaluation of Sources Containing Number of Worker Estimates 257
Table Apx E-4. Data Evaluation of Sources Containing Occupational Exposure Monitoring Data 258
Table_Apx E-5. Parameter Values for Calculating ADC 261
Table Apx E-6. Overview of Average Worker Tenure from U.S. Census SIPP (Age Group 50+) 263
Table_Apx E-7. Median Years of Tenure with Current Employer by Age Group 263
Table Apx E-8. Assigned Protection Factors for Respirators in OSHA Standard 29 CFR 1910.134... 267
Table Apx E-9. Number and Percent of Establishments and Employees Using Respirators within 12
Months Prior to Survey 268
Table Apx E-10. Summary of Assumptions, Uncertainty, and Overall Confidence in Release Estimates
by OES 270
Table Apx E-l 1. Summary of Assumptions, Uncertainty, and Overall Confidence in Inhalation
Exposure Estimates by OES 273
Table Apx E-12. Asbestos Concentrations for Common Legacy Construction Materials 276
Table_Apx E-13. Area of Asbestos Waste per Material 280
Table_Apx E-14. Average Concentration of Asbestos in Building Materials 281
Table_Apx E-15. Density of Asbestos-Containing Materials 281
Table Apx E-16. Wastewater Discharge Summary for Maintenance, Renovation, and Demolition
Activities 281
Table Apx E-17. Air Emission Summary for Maintenance, Renovation, and Demolition Activities... 282
Table Apx E-l8. Land Release Summary for Maintenance, Renovation, and Demolition Activities .. 282
TableApx E-19. Number of Employees and Establishments for Relevant NAICS Codes for
Maintenance, Renovation, and Demolition Activities 284
Table Apx E-20. Estimated Number of Workers Potentially Exposed to Asbestos During Maintenance,
Renovation, and Demolition Activities 285
Table Apx E-21. Summary of Inhalation Monitoring Data for Maintenance, Renovation, and
Demolition Activities for Higher-Exposure Potential Workers 286
Table Apx E-22. Summary of Inhalation Monitoring Data for Maintenance, Renovation, and
Demolition Activities for Lower-Exposure Potential Workers 286
Table Apx E-23. Summary of Inhalation Monitoring Data for Maintenance, Renovation, and
Demolition Activities for ONUs 286
Table Apx E-24. Wastewater Discharge Summary for Handling Asbestos-Containing Building
Materials During Firefighting or Other Disaster Response Activities 288
Table Apx E-25. Air Emission Summary for Handling Asbestos-Containing Building Materials During
Firefighting or Other Disaster Response Activities 288
Table Apx E-26. Land Release Summary for Handling Asbestos-Containing Building Materials During
Firefighting or Other Disaster Response Activities 289
Table Apx E-27. Estimated Number of Workers Potentially Exposed to Asbestos During Firefighting or
Other Disaster Response Activities 290
Table Apx E-28. Summary of Inhalation Monitoring Data for Firefighting and Other Disaster Response
Activities for Career Firefighters 291
Table Apx E-29. Summary of Inhalation Monitoring Data for Firefighting and Other Disaster Response
Activities for Volunteer Firefighters 291
Table Apx E-30. Legacy Asbestos Concentrations for Common Appliance and Machinery Components
293
Table Apx E-31. Air Emission Summary for Use, Repair, or Removal of Industrial and Commercial
Appliances or Machinery 294
Table Apx E-32. Land Release Summary for Use, Repair, or Removal of Industrial and Commercial
Appliances or Machinery 294
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TableApx E-33. Estimated Number of Workers Potentially Exposed to Asbestos During Use, Repair,
or Removal of Industrial and Commercial Appliances or Machinery 295
Table Apx E-34. Summary of Inhalation Monitoring Data for Use, Repair, or Removal of Appliances or
Machinery for Workers 296
Table Apx E-35. Summary of Inhalation Monitoring Data for Use, Repair, or Removal of Appliances or
Machinery for ONUs 297
Table Apx E-36. Asbestos Concentrations for Common Articles and Formulations 297
Table Apx E-37. Air Emission Summary for Handling Articles or Formulations that Contain Asbestos
299
Table Apx E-38. Land Release Summary for Handling Articles or Formulations that Contain Asbestos
299
Table Apx E-39. Estimated Number of Workers Potentially Exposed During Handling Articles or
Formulations that Contain Asbestos 301
Table Apx E-40. Summary of Inhalation Monitoring Data for Handling Articles and Formulations for
Higher-Exposure Potential Workers 302
Table Apx E-41. Summary of Inhalation Monitoring Data for Handling Articles and Formulations for
Lower-Exposure Potential Workers 302
Table Apx E-42. Summary of Inhalation Monitoring Data Handling Articles and Formulations for
ONUs 302
Table Apx E-43. Air Emission Summary for Waste Handling, Disposal, and Treatment 308
Table Apx E-44. Land Release Summary for Waste Handling, Disposal, and Treatment 308
Table Apx E-45. Estimated Number of Workers Potentially Exposed to Asbestos During Waste
Disposal Activities 310
Table Apx E-46. Summary of Inhalation Monitoring Data for Workers Handling Asbestos-Containing
Waste 311
Table Apx E-47. Summary of Occupational Inhalation Exposure Assessment for Asbestos 312
Table Apx E-48. SOCs with Worker and ONU Designations for All Occupational Exposure Scenarios
315
Table Apx E-49. Estimated Number of Potentially Exposed Workers and ONUs under NAICS 325199
317
TableApx F-l. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
Ambient Air 323
Table Apx F-2. Summary of Peer-Reviewed Literature that Measured Asbestos (s/cc) Levels in
Ambient Air 329
TableApx F-3. Summary of Published Literature for Measured Ambient Air Concentrations 330
Table Apx F-4. Procedures for Replacing Values of Physical Source Parameters from the National
Emissions Inventory 334
Table Apx F-5. Assumptions for Intraday Emission-Release Duration Used in AERMOD 335
Table Apx F-6. Assumptions for Interday Emission-Release Pattern Used in AERMOD 335
Table_Apx F-7. Settings for Particle Deposition 336
Table Apx F-8. Low-End Tendency Ambient Air Concentrations Summary by OES 341
Table Apx F-9. Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery
Containing Asbestos OES Central Tendency Ambient Air Concentrations Summary
Table 342
Table Apx F-10. Handling Asbestos-Containing Building Materials During Maintenance, Renovation,
and Demolition Activities OES Central Tendency Ambient Air Concentrations Summary
Table 342
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TableApx F-l 1. Handling Asbestos-Containing Building Materials During Firefighting or Other
Disaster Response Activities OES Central Tendency Ambient Air Concentrations
Summary Table 343
Table Apx F-12. Waste Handling, Disposal, and Treatment OES Central Tendency Ambient Air
Concentrations Summary Table 343
Table Apx F-13. Handling Articles or Formulations that Contain Asbestos OES Central Tendency
Ambient Air Concentrations Summary Table 343
Table Apx F-14. Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery
Containing Asbestos OES High-End Tendency Ambient Air Concentrations Summary
Table 343
Table Apx F-15. Handling Asbestos-Containing Building Materials during Maintenance, Renovation,
and Demolition Activities OES High-End Tendency Ambient Air Concentrations
Summary Table 344
Table Apx F-16. Handling Asbestos-Containing Building Materials During Firefighting or Other
Disaster Response Activities OES High-End Tendency Ambient Air Concentrations
Summary Table 344
Table Apx F-17. Waste Handling, Disposal, and Treatment OES High-End Tendency Ambient Air
Concentrations Summary Table 344
Table Apx F-l8. Handling Articles or Formulations that Contain Asbestos OES High-End Tendency
Ambient Air Concentrations Summary Table 345
Table_Apx F-19. Ambient Air Concentration Summary by OES 346
Table Apx F-20. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
Surface Water 350
Table Apx F-21. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
Drinking Water 354
Table Apx F-22. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
Groundwater 357
TableApx F-23. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cm3) Levels in the
TEM Method of Sediment 358
Table Apx F-24. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in the
TEM Method of Wastewater 358
TableApx F-25. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in the
TEM Method of Soil 359
Table Apx F-26. Summary of Peer-Reviewed Literature that Measured Asbestos (s/cc) Levels in the
PCM Method of Soil 359
TableApx G-l. Considerations that Inform Evaluations of the Strength of the Evidence within an
Evidence Stream (i.e., Apical Endpoints, Mechanistic, or Field Studies) 362
Table Apx H-l. Non-cancer Chronic Time Weighting Factors Assumptions for All COUs 371
Table Apx 1-1. Cohorts Identified for Consideration in Asbestos Part 2 Non-cancer Dose-Response
Analysis 373
Table Apx 1-2. Cohorts Identified for Consideration in Asbestos Part 2 Cancer Dose-Response Analysis
375
Table Apx J-l. Description of Selected Monitoring Studies of Clothes Handling for Take-Home
Analysis 379
Table Apx J-2. Take-Home Inhalation Risk Estimates Summary for All Populations Considered 385
Table Apx K-l. Less-than-Lifetime (LTL) IURs for Asbestos: Part2 387
Table Apx K-2. Occupational Part 1 and Part 2 IUR ELCR Comparison 388
Table Apx K-3. Take-Home Part 1 and Part 2 IUR ELCR Comparison 389
Table Apx K-4. Consumer DIY Part 1 and Part 2 IUR ELCR Comparison 389
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TableApx K-5. General Population Part 1 and Part 2 IUR ELCR Comparison 391
TableApx L-l. Lifetime Cancer Risk Estimate Comparison for Various LTL IUR Values 395
Table Apx L-2. Non-cancer Chronic Risk Estimate Comparison for Various ED Values 395
TableApx N-l. Limit of Detection (LOD) and Limit of Quantification (LOQ) Summary for Air
Sampling Analytical Methods Identified 405
LIST OF APPENDIX FIGURES
Figure_Apx F-l. Concentrations of Asbestos (f/cc) in Ambient Air from 1977 to 2021 322
Figure_Apx F-2. Concentrations of Asbestos (s/cc) in Ambient Air from 1975 to 2008 328
Figure_Apx F-3. Map of Specific Facilities by OES 332
FigureApx F-4. Ambient Air Concentrations for Facilities under the Handling Articles or Formulations
that Contain Asbestos OES 337
Figure Apx F-5. Ambient Air Concentrations for Facilities under Handling Asbestos-Containing
Building Materials During Maintenance, Renovation, and Demolition Activities OES 338
Figure Apx F-6. Ambient Air Concentrations for Facilities under Use, Repair, or Disposal of Industrial
and Commercial Appliances or Machinery Containing Asbestos OES 338
Figure Apx F-7. Ambient Air Concentrations for Facilities under Waste Handling, Disposal, and
Treatment OES 339
Figure Apx F-8. Generic Annual Ambient Air Asbestos Concentrations: Handling Asbestos-Containing
Building Materials during Firefighting or Other Disaster Response Activities 340
Figure Apx F-9. Generic Annual Ambient Air Asbestos Concentrations: Handling Asbestos-Containing
Building Materials during Maintenance, Renovation, and Demolition Activities 340
Figure Apx F-10. Generic Annual Ambient Air Concentrations Waste Handling, Disposal, and
Treatment Fugitive Emissions 341
Figure_Apx F-l 1. Concentrations of Asbestos (f/cc) in Surface Water from 1971 to 2016 349
Figure_Apx F-12. Concentrations of Asbestos (f/cc) in Drinking Water from 1971 to 2011 353
Figure_Apx F-13. Concentrations of Asbestos (f/cc) in Groundwater from 1980 to 2016 356
Figure Apx F-14. Concentrations of Asbestos (f/cm3) in the TEM Method of Sediment from 1995 to
1998 358
Figure Apx F-15. Concentrations of Asbestos (f/cc) in the TEM Method of Wastewater in Untreated
Effluent at Discharge Origin Locations in 1975 358
Figure Apx F-16. Concentrations of Asbestos (f/cc) in the TEM Method of Soil in Near Facility
Locations in 2010 359
Figure Apx F-l 7. Concentrations of Asbestos (s/cc) in the PCM Method of Soil in General Population
Locations from 2001 to 2012 359
Figure Apx M-l. Central Tendency Lifetime Cancer Risk Aggregation across Take-Home and DIY
Scenarios 397
Figure Apx M-2. Central Tendency Lifetime Cancer Risk Aggregation across Take-Home, DIYers, and
General Population Risks to Occupational Activities Releases to Ambient Air Scenarios
397
Figure Apx M-3. Central Tendency Lifetime Cancer Risk Aggregation across Workers, Take-Home,
DIYers, and General Population Risks to Occupational Activities Releases to Ambient
Air Scenarios 398
Figure Apx M-4. Lifetime Cancer Risk Aggregation across COUs for General Population, Take-Home
Exposures and High-Exposure Workers 399
Figure_Apx M-5. Non-cancer Chronic Risk Aggregate across DIY Activities 400
Figure Apx M-6. Non-cancer Chronic Aggregate Risk across CT Scenarios for Take-Home, LE DIYers,
and LE General Population Risk to Occupational Activities Releases to Ambient Air. 401
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655 Figure_Apx M-7. Central Tendency Non-cancer Chronic Aggregate Risk across Scenarios for Workers,
656 Take-Home, DIYers, and General Population Risk to Occupational Activities Releases to
657 Ambient Air 401
658 FigureApx M-8. Non-cancer, Chronic Risk Aggregation across COUs for General Population, Take-
659 Home Exposures, and High-Exposure Workers 402
660
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ACKNOWLEDGEMENTS
This report was developed by the United States Environmental Protection Agency (U.S. EPA or the
Agency), Office of Chemical Safety and Pollution Prevention (OCSPP), Office of Pollution Prevention
and Toxics (OPPT).
Acknowledgements
The Assessment Team gratefully acknowledges the participation, input, and review comments from
OPPT and OCSPP senior managers and science advisors as well as assistance from EPA contractors
Battelle (Contract No. EPW16017), ERG (Contract No. 68HERD20A0002), ICF (Contract No.
68HERC19D0003), SpecPro Professional Services, LLC (Contract No. 68HERC20D0021), General
Dynamics Information Technology, Inc. (Contract No. HHSN316201200013W), and SRC (Contract No.
68HERH19D0022). Special acknowledgement is given for the contributions of technical experts from
EPA's Office of Research and Development (ORD), including Thomas Bateson and Leonid Kopylev,
for their joint efforts.
As part of an intra-agency review, the draft Asbestos Part 2 Risk Evaluation was provided to multiple
EPA Program Offices. Comments were submitted by EPA's Office of Children's Health Protection
(OCHP), Office of General Council (OGC), ORD, and Office of Water (OW). The Asbestos Part 2 Risk
Evaluation scope and approaches were discussed with the EPA Offices noted above, as well as other
EPA Offices (Office of Air and Radiation [OAR], Office of Land and Emergency Management
[OLEM], and Regional Offices) and outside federal stakeholders including the Mine Safety and Health
Administration (MSHA), National Aeronautics and Space Administration (NASA), and United States
Geological Survey (USGS).
Docket
Supporting information can be found in public docket, Docket ID: (EPA-HQ-QPPT-2021-0254).
Disclaimer
Reference herein to any specific commercial products, process or service by trade name, trademark,
manufacturer or otherwise does not constitute or imply its endorsement, recommendation, or favoring by
the United States Government.
Authors: Collin Beachum, Jennifer Nichols (Management Leads), Brandall Ingle-Carlson, Emily
Nolan, Laura Krnavek (Assessment Leads), J. Aaron Murray, Juan Bezares Cruz, Ryan Sullivan,
Christelene Horton, Abhilash Sasidharan, Myles Hodge, Marcy Card, Robert Courtnage, Peter Gimlin,
Ana Corado, Rachel McAnallen, William Silagi, Todd Coleman, Marlyn Rodriguez, Chloe O'Haire,
Stephanie Schwarz.
Contributors: Thomas Bateson, Leonid Kopylev.
Technical Support: Mark Gibson, Hillary Hollinger.
This draft risk evaluation was reviewed by OPPT and OCSPP leadership.
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EXECUTIVE SUMMARY
EPA has evaluated asbestos under the Toxic Substances Control Act (TSCA). Asbestos is a naturally
occurring fibrous silicate mineral. Although there are six types of fibers—chrysotile, crocidolite,
amosite, anthophyllite, tremolite, actinolite—chrysotile is the only asbestos fiber type known to be
currently imported, processed, or distributed for use in the United States. Asbestos was primarily used
as a fire retardant in construction but has also been used extensively in manufacturing—including for
use in diaphragms used to make chlorine and caustic soda, gaskets, brakes and other friction products,
cement water pipes, and in buildings materials such as floor tiles, insulation (including on hot water
and steam pipes), roofing and siding shingles, textured paint and patching compounds—among other
uses. Asbestos fibers known as fibrils can get in the air and eventually into a person's lungs, which
may result in adverse health effects such as asbestosis (lung disease) and cancer including
mesothelioma (cancer of the abdominal lining) as week as lung, ovarian, and laryngeal cancers.
When asbestos was selected for TSCA risk evaluation in December 2016, EPA conducted its initial
risk evaluation on ongoing uses of chrysotile asbestos and excluded "legacy uses" (i.e., uses without
ongoing or prospective manufacturing, processing, or distribution for use) and "associated disposals"
(i.e., future disposal of legacy uses). In late 2019, a U.S. circuit court1 held that EPA should not have
excluded legacy uses or "associated disposals" from the evaluation. Examples of legacy uses include
floor and ceiling tiles, pipe wraps, insulation, heat protective textiles containing chrysotile and other
fiber types. Following this court ruling, EPA determined that the complete risk evaluation for asbestos
would be issued in two parts. The final Risk Evaluation for Asbestos Part 1: Chrysotile Asbestos was
released in December 2020. This draft document presents Part 2 of the risk evaluation of asbestos and
focuses on supplemental analyses, including legacy uses of asbestos and associated disposals and a
limited consideration of talc containing asbestos.2 Under the one-time asbestos reporting rule under
TSCA section 8(a), exposure-related information—including information on the presence, types, and
quantities of asbestos (including asbestos that is a component of a mixture) and asbestos-containing
articles that have been manufactured (including imported) or processed—will be provided to the
Agency in 2024, which will be considered in the final Part 2 risk evaluation consistent with TSCA
sections 26(h), (i), and (k), 15 U.S.C. 2625.
The uses of asbestos evaluated in this Part 2 draft risk evaluation include a wide range of exposure
scenarios and potentially exposed or susceptible subpopulations (PESS). One legacy use of asbestos is
as a fire retardant in building materials, which do not pose a risk until disturbed, but can be released
during construction, modification, or demolition of asbestos-containing materials (ACMs) in homes,
school, or commercial buildings. For example, exposure to asbestos can occur when construction
workers cut through pipes lined with asbestos, when do-it-yourself (DIY) home remodelers remove
asbestos-containing ceiling tiles, and when fire fighters enter buildings with disturbed asbestos during an
emergency. Relevant uses of imported talc products that may contain asbestos (i.e., fillers and putties
with talc containing asbestos and crayons with talc containing asbestos) were also considered, but there
were no reasonably available information identified to provide evidence that import of these products is
ongoing. The PESS with greatest risk from asbestos exposure include those with occupational exposure,
individuals exposed through DIY activities, children, and those who smoke with risk to respiratory
effects.
1 See in Safer Chemicals, Healthy Families v. EPA, 943 F.3d 397 (9th Cir. 2019); note that the court upheld EPA's exclusion
of "legacy disposals" (i.e., past disposals).
2 In addition to the final scope and this draft risk evaluation EPA released the White Paper: Quantitative Human Health
Approach to be Applied in the Risk Evaluation for Asbestos Part 2 - Supplemental Evaluation including Legacy Uses and
Associated Disposals of Asbestos in August 2023. The White Paper focused on the quantitative human health assessment and
dose-response considerations for Part 2 of the risk evaluation.
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Asbestos Part 2 Unreasonable Risk to Human Health
Epidemiologic evidence indicates that exposure to asbestos is associated with a range of health effects
including mesothelioma, lung, ovarian, and laryngeal cancers, as well as asbestosis and other non-cancer
respiratory effects. EPA evaluated the risks of people experiencing these cancers and harmful respiratory
effects from being exposed to asbestos via occupational exposure, "take-home" exposure (workers and
others exposed to asbestos fibers that may have been transferred to their homes), people who conduct
DIY projects that modify products that can release asbestos (such as home renovation projects that
dismantle asbestos-containing tiles), and the general population with asbestos released into the
environment (such as ACMs released during a structure fire or demolished in a nearby building). When
determining unreasonable risk of asbestos to human health, the Agency also accounted for potentially
exposed and susceptible populations—workers, children, individuals exposed through DIY activities,
and smokers (see Table 5-25).
The risks from asbestos stem from disturbing asbestos either through direct modification or proximity to
the activity or associated materials. EPA expects that the highest asbestos exposure potential exists for
workers involved with cutting, sanding, or grinding asbestos-containing material on a regular basis; for
example construction workers routinely involved in demolition work (Section 5.1.1). Career fire fighters
represent another at risk occupationally exposed group. Similarly, for take-home exposures, the highest
asbestos exposure potential derives from workers with direct asbestos exposure who bring asbestos
contaminated clothing back home and expose those cleaning and handling the garments (Section 5.1.2).
Next, for consumers engaged in DIY projects, high concentrations of asbestos exposure may arise from
activities such as home maintenance, large scale renovations, and removal activities involving asbestos-
containing products when modified through sanding, grinding, drilling, etc. (Section 5.1.4). In contrast,
general population exposures to asbestos increase with proximity to asbestos emitting activities such as
those described above (Section 5.1.4). The highest excess lifetime cancer risk (ELCR) caused by
asbestos exposure was found to be associated with occupational exposures, followed by general
population, then DIY and take-home exposures. The risk of non-cancer effects such as localized pleural
thickening was similar across exposure scenarios evaluated.
While the exposure scenarios in the risk evaluation did not assume compliance with existing federal
regulation, the monitoring data used may reflect the existing federal, state, and local regulations
requiring proper management of ACMs. Under the Asbestos Hazard Emergency Response Act
(AHERA) under Title II of TSCA, EPA issued regulations in the 1980s requiring local education
agencies (public school districts and non-profit private schools, including charter schools and schools
affiliated with religious institutions) to inspect their school buildings for asbestos, prepare asbestos
management plans, and perform asbestos response actions. AHERA also required EPA to develop a
model plan for states for training and accrediting persons conducting asbestos inspections and
corrective-action activities at schools and public and commercial buildings.
Under the Clean Air Act, the asbestos National Emission Standards for Hazardous Air Pollutants
(NESHAPs) regulations issued in 1973 specify work practices for asbestos to be followed during
renovations and prior to demolitions of all structures, installations, and buildings (excluding residential
buildings that have four or fewer dwelling units). Occupational Safety and Health Administration
(OSHA) regulates asbestos through standards for the construction industry, general industry, and
shipyard employment sectors. These standards require exposure monitoring, awareness training. When
asbestos exposure is identified, employers are required to establish regulated areas, controlling certain
work practices, instituting engineering controls, use administrative controls and, if needed, provide for
the wearing of personal protective equipment. OSHA standards also require proper handling of work
clothing to prevent "take-home" contaminated work clothing. Existing federal, state, and local asbestos
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regulatory requirements include work practices that reduce the release of asbestos fibers and therefore
may reduce exposure to people sufficiently to reduce risk below a level of concern. However, those
requirements do not apply to all work situations and EPA's high-end estimates cover those situations
where existing regulations do not apply. That is why there are high-end estimates that exceed EPA's
standard risk benchmarks: Existing regulations, while assumed to be effective at reducing exposure, do
not cover all activities considered in this draft risk evaluation. EPA focused on the high-end risk
estimates to represent situations where workers, including people hired to perform home renovation
work, may not be subject to existing asbestos regulatory requirements or follow work practices to reduce
asbestos exposure. EPA's risk evaluation showed that there are situations where workers, including self-
employed persons hired to perform home renovation work, may not be subject to existing asbestos
regulatory requirements, or do not follow work practices to reduce asbestos exposure, or may not be
aware that asbestos is present at the worksite.
In this Part 2 draft risk evaluation, EPA's assessment preliminarily determines that the following
asbestos conditions of use (COUs) contribute to the unreasonable risks of cancer and non-cancer
health effects:
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - construction and building materials covering large surface areas - paper articles;
metal articles; stone plaster, cement, glass, and ceramic articles;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - machinery, mechanical appliances, electrical/electronic articles;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - other machinery, mechanical appliances, electronic/electronic articles;
• Industrial/commercial use - chemical substances in furnishing, cleaning, treatment care products
- construction and building materials covering large surface areas - fabrics, textiles, and apparel;
• Industrial/commercial use - chemical substances in furnishing, cleaning, treatment care products
- furniture and furnishings - stone, plaster, cement, glass, ceramic articles, metal articles, and
rubber articles;
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
construction and building materials covering large surface areas - paper articles; metal articles;
stone, plaster, cement, glass, and ceramic articles;
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
fillers and putties;
• Consumer use - chemical substances in furnishing, cleaning, treatment care products - furniture
and furnishings - stone, plaster, cement, glass, and ceramic articles; metal articles; or rubber
articles; and
• Disposal - distribution for disposal.
The unreasonable risk is due to exposures to (1) people who handle asbestos products, (2) exposed
workers taking asbestos home, (3) non-professional do-it-yourself (DIY) exposure scenarios, and
(4) the general population within the vicinity of activities releasing asbestos to the environment.
The EPA preliminarily determined that the following asbestos COUs were not found to contribute to
unreasonable risks of cancer and non-cancer health effects:
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - fillers and putties;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - solvent based/water based paint;
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• Industrial/commercial use - chemical substances in products not described by other codes -
other (aerospace applications): based on the description of activities related to aerospace
applications;
• Industrial/commercial use - mining of non-asbestos commodities - mining of non-asbestos
commodities: based on data and information from MSHA and stakeholders, EPA has determined
that exposure to asbestos is unlikely;
• Industrial/ commercial use - laboratory chemicals - laboratory chemicals: based on EPA
analysis of vermiculite products, EPA does not expect any significant asbestos releases or
occupational exposures;
• Industrial/commercial use - chemical substances in automotive, fuel, agriculture, outdoor use
products - lawn and garden care products: based on EPA analysis of vermiculite products, EPA
does not expect any significant asbestos releases or occupational exposures; and
• Consumer use - chemical substances in automotive, fuel, agriculture, outdoor use products -
lawn and garden care products: based on EPA analysis of vermiculite products, EPA does not
expect any significant asbestos exposures to consumers.
Asbestos Part 2 Unreasonable Risk to the Environment
Although asbestos is no longer mined in the United States, releases of asbestos to the environment
persist due to legacy uses and associated disposals of asbestos containing materials such as old building
materials, brake pads, oil gaskets, and pipe insulation. The strong Si-O-Si covalent bonds found within
asbestos fibers are responsible for its inherent environmental stability, negligible water solubility, high
tensile strength, hardness, and inherent chemical inertness. Small asbestos fibers suspended in the air
eventually settle into soils and water bodies, where negligible solubility leads to deposition into
sediments and biosolids. EPA assessed exposures to aquatic organisms (surface water and sediment) and
terrestrial organisms (air, water, and soil), but found limited uptake of asbestos fibers in these
environmental media. Aquatic hazard data were available for asbestos from a total of six fish and
aquatic invertebrate (Asiatic clam) studies. No aquatic plant studies were reasonably available. EPA did
not characterize hazard to terrestrial species because the toxicological endpoints associated with the
ecological assessment of terrestrial species are not relevant for asbestos. Due to limited uptake of
asbestos fibers in the environment by animals and plants and limited adverse hazard effects, EPA
preliminarily determines that there is no risk of injury to the environment from asbestos that
would contribute to the unreasonable risk determination.
Unreasonable Risk of Asbestos as a Chemical Substance
As further explained in Section 6.1 of this draft risk evaluation, a single unreasonable risk determination
is made for asbestos as a chemical substance that includes both the conditions of use evaluated in the
2020 Risk Evaluation for Asbestos, Part 1: Chrysotile Asbestos and the conditions of use evaluated in
this draft Risk Evaluation for Part 2: Supplemental Evaluation Including Legacy Uses and Associated
Disposals. The unreasonable risk determination is based on the existing risk characterization section of
the 2020 Risk Evaluation, Part 1: Chrysotile Asbestos (Section 4) and does not involve additional
technical or scientific analysis. The draft risk determination for asbestos as a chemical substance is also
based on the risk estimates (Sections 4 and 5) presented for the conditions of use (Section 1.1.2) in this
draft Risk Evaluation for Part 2: Supplemental Evaluation Including Legacy Uses and Associated
Disposals.
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1 INTRODUCTION
Asbestos is a naturally occurring fibrous mineral with six types of fibers—chrysotile, crocidolite,
amosite, anthophyllite, tremolite, actinolite—however, chrysotile is the only asbestos fiber type known
to be imported, processed, or distributed for use in the United States. EPA has recently issued a final
rule under TSCA to prohibit the ongoing manufacture (including import), processing, distribution in
commerce and commercial use of chrysotile asbestos (89 FR 21970, March 28, 2024 (FRL-8332-01-
OCSPP)). Domestically, chrysotile asbestos was primarily used as a fire retardant in construction and
building materials but was most recently used in chlor-alkali diaphragms used to produce chlorine and
caustic soda, in sheet gaskets used in chemical manufacturing, brake blocks used on drilling rigs,
imported brakes and linings, other vehicle friction products and other gaskets. This document presents
Part 2 of the Risk Evaluation for Asbestos under the Frank R. Lautenberg Chemical Safety for the 21st
Century Act that amended TSCA in June 2016. The Agency began its risk evaluation of asbestos when it
was identified as one of the first 10 chemicals for risk evaluation under amended TSCA. Part 2 is a
response to the ruling from the court in Safer Chemicals, Healthy Families v. EPA, 943 F.3d 397 (9th
Cir. 2019) holding that EPA should not have excluded "legacy uses" or "associated disposals" from
consideration (see also Section 1.1). Examples of legacy uses include floor and ceiling tiles, pipe wraps,
insulation, and heat protective textiles containing chrysotile and other fiber types.
Section 1.1 provides an overview of the scope of Part 2 of the Risk Evaluation for Asbestos, including
production volume, life cycle diagram (LCD), conditions of use (COUs), and conceptual models used
for asbestos; Section 1.2 includes an overview of the systematic review process; and Section 1.3
presents the organization of this draft risk evaluation. Figure 1-1 describes the major inputs, phases, and
outputs/components of the TSCA risk evaluation process—from scoping to releasing the final risk
evaluation.
Inputs
Existing Laws, Regulations,
and Assessments
Use Document
Public Comments
Public Comments on
Draft Scope Document
Analysis Plan
• Testing Results
Data Evaluation Process
Data Integration
Public Comments on
Draft RE
Peer Review Comments
on Draft RE
Phase
Outputs
Figure 1-1. TSCA Existing Chemical Risk Evaluation Process
1.1 Scope of the Risk Evaluation
For Part 1 of the Risk Evaluation for Asbestos, EPA initially adopted the definition of asbestos as
defined by TSCA Title II (added to TSCA in 1986), section 202 as the "asbestiform varieties of six fiber
types - chrysotile (serpentine), crocidolite (riebeckite), amosite (cummingtonite-grunerite),
anthophyllite, tremolite, or actinolite." However, a choice was made to focus Part 1 solely on chrysotile
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asbestos as this is the only asbestos fiber type that is currently imported, processed, or distributed in the
United States. EPA informed the public of this decision to focus on ongoing uses of asbestos and
exclude legacy uses and disposals in the Scope of the Risk Evaluation for Asbestos, released in June
2017 (U.S. EPA. 2017). However, as noted above, in late 2019, the court in Safer Chemicals, Healthy
Families v. EPA, 943 F.3d 397 (9th Cir.) held that EPA's Risk Evaluation Rule (82 FR 33726 [July 20,
2017]) should not have excluded "legacy uses" (i.e., uses without ongoing or prospective manufacturing,
processing, or distribution for use) or "associated disposals" (i.e., future disposal of legacy uses) from
the definition of conditions of use (COUs)—although the court did uphold EPA's exclusion of "legacy
disposals" (i.e., past disposals). Following that court ruling, EPA continued development of the risk
evaluation for the ongoing uses of chrysotile asbestos and determined that the complete risk evaluation
for asbestos would be issued in two parts. The Risk Evaluation for Asbestos Part 1: Chrysotile
Asbestos—also referred to as the "2020 Part 1 Risk Evaluation for Asbestos", "Part 1 Risk Evaluation",
and "Part 1"—was released in December (U.S. EPA. 2020c). allowing the Agency to expeditiously
move into risk management for the unreasonable risk identified in Part 1 for ongoing chrysotile COUs
with unreasonable risk.
EPA used reasonably available information, defined in 40 CFR 702.33, in a fit-for-purpose approach,
to develop a risk evaluation that relies on the best available science and is based on the weight of
scientific evidence. EPA evaluated the quality of the methods and reporting of results of the individual
studies using the evaluation strategies described in the Draft Systematic Review Protocol Supporting
TSCA Risk Evaluations for Chemical Substances (U.S. EPA. 2021).
Following the finalization of Part 1 of the Risk Evaluation for Asbestos, EPA OPPT immediately began
development of Part 2 of the Draft Risk Evaluation for Asbestos (Part 2 of the risk evaluation, or Part 2),
starting with the issuance of a draft scope document. The Final Scope of the Risk Evaluation for
Asbestos Part 2: Supplemental Evaluation Including Legacy Uses and Associated Disposals of Asbestos
(87 FR 38746) (EPA-HQ-2021 -0254-0044; hereafter "Final Scope") was released in June 2021,
reflecting consideration of public comments on a draft scope document. Although Part 1 of the Risk
Evaluation adopted the TSCA Title II definition of asbestos, the consideration of legacy uses and
associated disposals that will be evaluated in Part 2 warrant broader considerations as asbestos can be
co-located geologically with commercially mined substances. In particular, Libby amphibole asbestos
(LAA) is known to have been present with vermiculite, extracted from an open pit mine near Libby,
Montana, until the mine closed in 1990. Vermiculite was widely used in building materials which are an
important focus of the evaluation of legacy uses of asbestos. Thus, LAA (and its tremolite, winchite, and
richterite constituents) were considered in this Part 2 of the risk evaluation. EPA also determined the
relevant COUs of asbestos-containing talc, including any "legacy use" and "associated disposal" where
asbestos is implicated in Part 2. Where the Agency identifies reasonably available information
demonstrating asbestos-containing talc COUs that fall under TSCA authority, these were also evaluated
in Part 2 of the risk evaluation.
In addition to the Final Scope and prior to this Part 2 draft risk evaluation, EPA released the White
Paper: Quantitative Human Health Approach to be Applied in the Risk Evaluation for Asbestos Part 2
- Supplemental Evaluation including Legacy Uses and Associated Disposals of Asbestos in August
2023 (U.S. EPA. 2023o) (hereafter the "White Paper) for a 60-day comment period and an external
letter peer review. The White Paper focused on the quantitative human health assessment and dose-
response considerations for Part 2 of the risk evaluation. EPA has continued to focus the human health
assessment in Part 2 on epidemiologic evidence, evaluating cancer and non-cancer evidence and
conclusions from the existing EPA assessments in addition to other studies identified from a recently
conducted systematic review approach. The White Paper described the systematic review
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considerations and criteria for identifying studies for dose-response analysis, evaluated, and compared
existing cancer inhalation unit risks (IURs) and the non-cancer point of departure (POD) with the
results of the new systematic review, and proposed a cancer IUR and non-cancer POD for use in Part
2. Several key findings and conclusions from EPA's White Paper are provided below:
• OPPT conducted systematic review to identify the reasonably available information relevant
for consideration in the quantitative human health approach to be applied in Part 2 of the Risk
Evaluation for Asbestos. This included identification of cancer and non-cancer epidemiologic
studies from oral, dermal, and inhalation routes of exposure.
• OPPT has not identified any cancer or non-cancer epidemiologic studies from oral or dermal
exposures that support dose-response analysis; therefore, OPPT is not proposing cancer or non-
cancer values for these routes.
• For inhalation exposures, OPPT has identified several inhalation epidemiologic studies (or
cohorts) for non-cancer effects, including some that were considered in the IRIS LAA
Assessment (U.S. EPA. 2014c). However, none of those studies warranted an updated dose-
response analysis for the non-cancer POD. OPPT is proposing to use the existing POD of
2.6x 10~2 fiber/cc from the IRIS LAA Assessment to assess non-cancer risks in Part 2 with
application of appropriate uncertainty factors (UFs).
• OPPT did not identify any inhalation cancer cohorts beyond those considered by previous EPA
assessments, including for cancers other than mesothelioma and lung cancer, which would
warrant an updated dose-response assessment.
• The existing EPA-derived IURs—0.23, 0.17, and 0.16 per fiber/cc—are based on lung cancer
and mesothelioma with quantitative adjustment for laryngeal and ovarian cancers in the
development of the IUR of 0.16 per fiber/cc in the Part 1 Risk Evaluation. Despite each value
being derived from different information and epidemiologic cohorts, and therefore having
different strengths and uncertainties, the values are notably similar and round to 0.2 per
fiber/cc. OPPT is proposing to use an IUR of 0.2 per fiber/cc in Part 2 of the Draft Risk
Evaluation for Asbestos.
An additional expansion of considerations in Part 2, pertains to the evaluation of human health effects,
consideration of risk from take-home exposures and general population exposures from environmental
releases. Although Part 1 focused on certain cancer outcomes known to be causally related to asbestos
exposure (IARC. 2012a. 1977). Part 2 considers non-cancer outcomes at the system level or higher.
Historically, there has been a focus on inhalation exposures in asbestos health assessments conducted by
the EPA and other organizations, but there has also been interest in the updated literature on dermal and
oral exposures. These routes of exposure are being considered in Part 2, which EPA agreed to consider
as part of an agreement that was reached for the purpose of resolving a petition for review of Part 1 of
the Risk Evaluation (seeADAO, etal. v. EPA, No. 21-70160 (9th Cir. Oct. 2021)). A broad range of
health effects are examined in the asbestos epidemiologic literature including cancer (e.g.,
mesothelioma, lung, ovarian, laryngeal, gastrointestinal cancers) and non-cancer (e.g., asbestosis, lung
function decrements, pleural plaques/abnormalities, immune-related effects, cardiovascular effects)
outcomes. This range of human health outcomes was presented in Figure 2-10 in the Final Scope, and an
interactive version of this diagram is available Heat Map of Hazard Screening Results for Asbestos.
1.1.1 Life Cycle and Production Volume
The Life Cycle Diagram (LCD)—which depicts the COUs that are within the scope of the risk
evaluation during various life cycle stages, including industrial, commercial, and consumer uses of
legacy asbestos materials, as well as talc and vermiculite products that may contain asbestos—was
previously included in the Final Scope of the Risk Evaluation for Asbestos Part 2 (U.S. EPA. 2022b).
The LCD has been updated since it was included in the Scope document. Specifically, the relevant uses
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1015 of imported talc products that may contain asbestos (i.e., fillers and putties with talc containing asbestos,
1016 crayons with talc containing asbestos, and toy crime scene kits with talc containing asbestos) have been
1017 combined into a singular LCD shown in Figure 1-2. However, there were no reasonably available data
1018 identified that provide evidence that import of these products is ongoing. Under the one-time asbestos
1019 reporting rule under TSCA section 8(a), exposure-related information, including information on the
1020 presence, types, and quantities of asbestos (including asbestos that is a component of a mixture) and
1021 asbestos-containing articles that have been manufactured (including imported) or processed, will be
1022 provided to the Agency in 2024, which will be considered in the final risk evaluation consistent with
1023 TSCA sections 26(h), (i), and (k), 15 U.S.C. 2625.
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ASBESTOS (CAS RN 1332-21-4}
INDUSTRIAL, COMMERCIAL, CONSUMER USES WASTE DISPOSAL
Chemical Substances in Construction, Paint, Electrical, and Metal
Products
e.g., corrugated paper, roofing felt, cement, shingles, electrical panels,
transformers, fillers and putties, steel pipelines, and terminal insulators
Chemical Substances in Furnishing, Cleaning, Treatment Care Products
e.g., asbestos textiles, iron rests and burner mats, barbecue mitts, pot holders
Chemical Substances in Packaging, Paper, Plastic, Toys, Hobby Products
e.g., asbestos reinforced plastics, missile liner, mineral kits, crayons with talc
containing asbestos, toy crime scene kits with talc containing asbestos
Chemical Substances in Automotive, Fuel, Agriculture, Outdoor Use
Products
e.g., asbestos-containing vermiculite soil treatment
Laboratory Chemicals
e.g., vermiculite packaging products
Mining of Non-Asbestos Commodities
e.g., talc and vermiculite
Other Uses
e.g., artifacts in museums and collections, vintage cars, articles, curios, other
aerospace applications: RS-25 engine thermal isolator blocks
Non-TSCA Use
e.g., cosmetics and personal care products not covered by TSCA
See Conceptual Model for
Environmental Releases and
Wastes
Industrial/
I 1 Commercial/
Consumer Uses
Figure 1-2. Legacy Asbestos Life Cycle Diagram
See Table 1-1 for categories and subcategories of conditions of use. Potential exposures to fillers and putties with talc that contains asbestos are captured
within the occupational and consumer exposure assessments and are not assessed separately.
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Descriptions of the industrial, commercial, and consumer use categories identified from the Instructions
for Reporting 2020 TSCA Chemical Data Reporting (U.S. EPA, 2020b) were used in the
characterization of legacy asbestos uses shown in the Life Cycle Diagram (Figure 1-2). The CDR
descriptions provide a brief overview of each use category; Appendix E contains more detailed
descriptions (e.g., process descriptions, worker activities, process flow diagrams, equipment
illustrations) for each industrial and commercial use.
1.1.2 Conditions of Use Included in the Risk Evaluation
The Final Scope document identified and described the categories and subcategories of COUs that EPA
planned to consider in the risk evaluation. In this Part 2 draft risk evaluation, EPA made an edit to the
COUs listed in the final scope document. The edit reflects EPA's improved understanding of the COU
based on further review of all reasonably available information. The final scope document included the
following COU: "Industrial/commercial uses - chemical substances in packaging, paper, plastic, toys,
hobby products - toys intended for children's use (and child dedicated articles), including fabrics,
textiles, and apparel; or plastic articles (hard)" After reviewing the information available, EPA
concluded that the mineral kits identified are not used in an industrial or commercial settings, and any
possible use by a professor or a teacher would be represented by the consumer use of such articles. The
change also impacts the name of another related COU: "Industrial/commercial uses - chemical
substances in packaging, paper, plastic - Packaging (excluding food packaging), including rubber
articles; plastic articles (hard); plastic articles (soft)." The change is reflected in Table 1-1 presenting all
COUs for asbestos.
The conditions of use included in the draft risk evaluation are those reflected in the life cycle diagram
and conceptual models. These conditions of use were evaluated for chronic, and lifetime exposures, as
applicable based on reasonably available exposure and hazard data as well as the relevant routes of
exposure for each.
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1055 Table 1-1. Conditions of Use (Life Cycle, Categories, and Subcategories) and Examples of Items/Applications in the Risk Evaluation
1056 for Asbestos
Life Cycle Stage"
Category6
Subcategoryc
Item/Application
Reference(s)
Construction and building
materials covering large
surface areas, including paper
articles; metal articles; stone,
plaster, cement, glass, and
ceramic articles
Siding; corrugated paper (for use in pipe wrap insulation and
appliances); commercial papers, millboard; rollboard;
specialty paper; roofing felt; cement; shingles; corrugated
cement; ceiling tiles; loose-fill insulation (asbestos-
containing vermiculite); asbestos cement pipes and ducts
(water, sewer and air); asbestos (wallboard & joint
compound); wall protectors; air duct insulation; soldering
and welding blocks and sheets; stove gaskets and rings;
asbestos-coated steel pipelines; flooring felt; vinyl floor tiles
U.S. EPA (1989)
EPA 2021
(vermiculite
webpaee)
Industrial/
Chemical
Substances in
Machinery, mechanical
appliances,
electrical/electronic articles
Corrugated commercial and specialty papers; reinforced
plastics for appliances such as ovens, dishwashers, boilers,
and toasters; miscellaneous electro-mechanical parts for
appliances including deep fryers, frying pans and grills,
mixers, popcorn poppers, slow cookers, washers and dryers,
refrigerators, curling irons, electric blankets, portable
heaters, safes, safety boxes, filing cabinets, and kilns and
incinerators
U.S. EPA (1989)
Commercial Uses
Construction,
Paint, Electrical,
and Metal
Products
Other machinery, mechanical
appliances,
electronic/electronic articles
Braking and gear-changing (clutch) components in a variety
of industrial and commercial machinery including combines,
mining equipment, construction equipment such as cranes
and hoists, heavy equipment used in various manufacturing
industries (e.g., machine tools and presses), military
equipment, marine engine transmissions, and elevators;
packings/seals in rotary, centrifugal, and reciprocating
pumps, valves, expansion joints, soot blowers, and other
types of mechanical equipment; electro-mechanical parts
including commutators, switches, casings, and thermoplugs;
arc chutes; electrical panels; transformers (high grade
electrical paper)
U.S. EPA (1989)
Fillers and putties
Adhesives and sealants; extruded sealant tape; rubber and
vinyl sealants; epoxy adhesives;
U.S. EPA (1989)
Solvent-based/water-based
paint
Coatings; corrugated coatings; textured paints; vehicle
undercoating
U.S. EPA (1989)
Electrical batteries and
accumulators
Insulator for terminals
U.S. EPA (1989)
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Life Cycle Stage"
Category6
Subcategoryc
Item/Application
Reference(s)
Industrial/
Commercial Uses
Chemical
Substances in
Furnishing,
Cleaning,
Treatment Care
Products
Construction and building
materials covering large
surface areas, including
fabrics, textiles, and apparel
Asbestos textiles including yarn, thread, wick, cord, rope,
tubing (sleeving), cloth, and tape
U.S. EPA (1989)
Furniture & furnishings
including stone, plaster,
cement, glass, and ceramic
articles; metal articles; or
rubber articles
Iron rests; burner mats; barbecue mitts; pot holders
CPSC-EPA 1979
(44 FR 60056)
Chemical
Substances in
Packaging, Paper,
Plastic
Packaging (excluding food
packaging), including rubber
articles; plastic articles (hard);
plastic articles (soft)
Asbestos reinforced plastics
U.S. EPA (1989)
Chemical
Substances in
Automotive,
Fuel, Agriculture,
Outdoor Use
Products
Lawn and garden care
products
Asbestos-containing vermiculite soil treatment
U.S. EPA (2000a)
Mining of Non-
Asbestos
Commodities
Mining of non-asbestos
commodities
Metal and nonmetal mines, surface coal mines, and surface
areas of underground coal mines
MSHA 2008 (41
FR 11284)
Laboratory
chemicals
Laboratory chemicals
Vermiculite packaging products
U.S. EPA (2000a)
(IHC World.
2023)
Chemical
Substances in
Products not
Described by
Other Codes
Other (artifacts)
Artifacts in museums and collections
Other (aerospace
applications)
Other aerospace applications including RS-25 engine
thermal isolator blocks; high-performance plastics for
aerospace including heat shields, rocket motor casings, and
rocket motor liners
U.S. EPA (1989)
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Life Cycle Stage"
Category6
Subcategoryc
Item/Application
Reference(s)
Construction and building
materials covering large
surface areas, including paper
articles; metal articles; stone,
plaster, cement, glass, and
ceramic articles
Siding; corrugated paper (for use in pipe wrap insulation and
appliances); commercial papers; millboard; rollboard;
specialty paper; roofing felt; cement; shingles; corrugated
cement; ceiling tiles; loose-fill insulation (asbestos-
containing vermiculite); asbestos cement pipes and ducts
(water, sewer, and air); Galbestos; fireplace embers; stove
gaskets and rings; flooring felt; vinyl floor tiles
U.S. EPA (1989)
EPA 2021
(vermiculite
webpaee)
Chemical
Substances in
Construction,
Paint, Electrical,
and Metal
Products
Machinery, mechanical
appliances, electrical/
electronic articles
Corrugated commercial and specialty papers; reinforced
plastics for appliances such as ovens, dishwashers, boilers
and toasters; miscellaneous electro-mechanical parts for
appliances including deep fryers, frying pans and grills,
mixers, popcorn poppers, slow cookers, washers and dryers,
refrigerators, curling irons, electric blankets, portable
heaters, safes, safety boxes, filing cabinets, and kilns and
incinerators
U.S. EPA (1989)
Consumer Uses
Fillers and putties
Adhesives and sealants; extruded sealant tape
U.S. EPA (1989)
Solvent-based/water-based
paint
Coatings; textured paints; vehicle undercoating
U.S. EPA (1989)
Chemical
Substances in
Furnishing,
Cleaning,
Treatment Care
Products
Construction and building
materials covering large
surface areas, including
fabrics, textiles, and apparel
Asbestos textiles including yarn, thread, wick, cord, rope,
tubing (sleeving), cloth, tape
U.S. EPA (1989)
Furniture and furnishings,
including stone, plaster,
cement, glass, and ceramic
articles; metal articles; or
rubber articles
Iron rests; burner mats; barbecue mitts; potholders, and
similar items
CPSC-EPA 1979
(44 FR 60056)
Chemical
Substances in
Packaging, Paper,
Packaging (excluding food
packaging), including rubber
articles; plastic articles (hard);
plastic articles (soft)
Asbestos reinforced plastics
U.S. EPA (1989)
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Life Cycle Stage"
Category6
Subcategoryc
Item/Application
Reference(s)
Consumer Uses
Plastic, Toys,
Hobby Products
Toys intended for children's
use (and child dedicated
articles), including fabrics,
textiles, and apparel; or
plastic articles (hard)
Mineral kits
(ODOE. 2023)
(WST. 2019)
Chemical
Substances in
Automotive,
Fuel, Agriculture,
Outdoor Use
Products
Lawn and garden care
products
Asbestos-containing vermiculite soil treatment
U.S. EPA (2000a)
Chemical
Substances in
Products not
Described by
Other Codes
Other (artifacts)
Vintage artifacts in private collections; vintage cars, articles,
curios
CPSC-EPA 1979
(44 FR 60056)
Disposal, including
Distribution for
Disposal
Disposal,
including
Distribution for
Disposal
Disposal, including
distribution for disposal
Articles containing asbestos, demolition debris
11 Life Cycle Stage Use Definitions (40 CFR 711.3)
- "Industrial use" means use at a site at which one or more chemicals or mixtures are manufactured (including imported) or processed.
- "Commercial use" means the use of a chemical or a mixture containing a chemical (including as part of an article) in a commercial enterprise providing
saleable goods or services.
- "Consumer use" means the use of a chemical or a mixture containing a chemical (including as part of an article, such as furniture or clothing) when sold to
or made available to consumers for their use.
- Although EPA has identified both industrial and commercial uses here for purposes of distinguishing scenarios in this document, the Agency interprets the
authority over "any manner or method of commercial use" under TSCA section 6(a)(5) to reach both.
h These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly represent conditions of use of asbestos in industrial
and/or commercial settings.
c These subcategories reflect more specific conditions of use of asbestos.
1057
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1058 1.1.2.1 Conceptual Models
1059 The conceptual model in Figure 1-3 presents the exposure pathways, exposure routes and hazards to
1060 human populations from industrial and commercial activities and uses of asbestos. Figure 1-4 presents
1061 the conceptual model for consumer activities and uses, Figure 1-5 presents general population exposure
1062 pathways and hazards for environmental releases and wastes, and Figure 1-6 presents the conceptual
1063 model for ecological exposures and hazards from environmental releases and wastes.
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CONCEPTUAL MODEL FOR HUMAN EXPOSURE FROM INDUSTRIAL AND COMMERCIAL ACTIVITIES AND USES
INDUSTRIAL AND COMMERCIAL ACTIVITIES/USES PATHWAYS EXPOSURE ROUTES
POPULATIONS
EXPOSED
EFFECTS
1065
1066
1067
1068
1069
1070
Chemical Substances in Construction, Paint,
Electrical, and Metal Products
Chemical Substances in Furnishing, Cleaning,
Treatment Care Products
Chemical Substances in Packaging, Paper, Plastic,
Toys, Hobby Products
Chemical Substances in Automotive, Fuel,
Agriculture, Outdoor Use Products
Laboratory Chemicals (Vermiculite Packaging)
Mining of Non-Asbestos Commodities
Other Uses (Artifacts in Museums, Other
Aerospace Applications)
Non-TSCA Uses
Waste Handling,
Treatment and
Disposal**
Liquid/Solid Contact
Fugitive Dust
Emissions
Indoor Air —
Outdoor Air —
^ Dust, Solid Contact
Dermal [- ~
Oral*
Inhalation
Hazards potentially
associated with
lifetime cancer
and/or non-cancer
chronic exposures
KEY:
Grey text
Pathways and Routes
that were not further
assessed
^
Pathways and Routes
that were further
assessed
Pathways and Routes
that were not further
assessed
Wastewater, Solid Wastes, Air Emissions . «.u u • • 4.- * u * ^ u ^/u ^ -4. • • * 4- 4-4-u +
* Oral exposure may occur through incidental ingestion of asbestos residue on hand/body or through deposits in the upper respiratory tract that are
eventually swallowed.
** Includes wastes from industrial, commercial and consumer uses.
Figure 1-3. Conceptual Model for Industrial and Commercial Activities and Uses: Potential Exposure and Hazards
Some products are used in both commercial and consumer applications. See Table 1-1 for categories and subcategories of conditions of use. Distribution in
commerce not included in LCD. For the purposes of the risk evaluation, distribution in commerce is the transportation associated with moving chemical
substances in commerce. Unloading and loading activities are associated with other conditions of use. When data and information were available to
support the analysis, EPA also considered the effect that engineering controls and/or personal protective equipment have on occupational exposure level.
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CONCEPTUAL MODEL FOR CONSUMER ACTIVITIES AND USES: HUMAN POPULATION EXPOSURES/EFFECTS
CONSUMER ACTIVITIES/
USES'
EXPOSURE
PATHWAYS
EXPOSURE
ROUTES
POPULATIONS
EXPOSED*
HAZARDS
Chemical Substances in Construction,
Paint, Electrical, and Metal Products
Chemical Substances in Furnishing.
Cleaning, Treatment Care Products
Chemical Substances in Packaging. Paper.
Plastic. Toys. Hobby Products
Chemical Substances in Automotive, Fuel,
Agriculture, Outdoor Use Products
Chemical Substances in Products not
Described by Other Codes
\
/
Consumers
Activity-Based
Fiber Emissions b
x
Indoor Outdoor
Suspended Fibers
Inhalation
i
Hazards Potentially
Associated with Lifetime
Cancer and or Non-Canter
Chronic Exposures j
-~ Bystanders
Key:
Gray Text
Solid Arrow
Dash Arrow
Pathways and routes that were not assessed
Pathways and routes that were further assessed
Pathways and routes that were not assessed
1071
1072
1073
1074
1075
1076
Wastewater, Liquid Wastes and Solid
*¦ Wastes (See Environmental Releases
Conceptual Models '/
Figure 1-4. Asbestos Conceptual Model for Consumer Activities and Uses: Potential Exposures and Hazards
The conceptual model presents the exposure pathways, exposure routes and hazards to human from consumer activities and uses of asbestos.
a Some products are used in both commercial and consumer applications. See Table 1-1 for categories and subcategories of conditions of use.
b Human exposure occurs through inhalation of asbestos fibers released during activity-based scenarios.
0 Populations for estimating exposure include potentially exposed or susceptible subpopulations (PESS).
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RELEASES AND WASTES FROM INDUSTRIAL
COMMERCIAL / CONSUMER USES
EXPOSURE PATHWAYS
EXPOSURE ROUTES
POPULATIONS
EXPOSED b
Industrial Pre-
—~ Treatment or
Industrial WWT
Indirect discharge
±
Wastewater or
Liquid Wastes
Solid Wastes
Liquid Wastes
Emissions to Air
1077
1078
1079
1080
1081
1082
1083
Hazardous and
-+¦ Municipal Waste
Landfill
Hazardous and
Municipal Waste
Incinerators
Off-site Waste
Transfer
\
r
X.
Water. Sediment4
Soil
Fugitive Emissions
Aquatic \
Species J
Drinking
Water
Ground
Water
General
Population
Hazards Potentially
Associated with Lifetime
Cancer and or Non-Cancer
Chronic Exposures
r
Recycling, Other
Treatment
Key:
Gray Text Pathways and routes that were not assessed
Solid Arrow Pathways and routes that were further assessed
Dash Arrow Pathways and routes that were not assessed
Figure 1-5. Asbestos Conceptual Model for Environmental Releases and Wastes: General Population Exposures and Hazards
The conceptual model presents the exposure pathways, exposure routes and hazards to humans from releases and wastes from industrial, commercial,
and/or consumer uses of asbestos.
" Industrial wastewater or liquid wastes may be treated on-site and then released to surface water (direct discharge), or pre-treated and released to publicly
owned treatment works (POTW) (indirect discharge). For consumer uses, such wastes may be released directly to POTW (i.e., down the drain).
b Populations for estimating exposure include potentially exposed or susceptible subpopulations.
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RELEASES AND WASTES FROM INDUSTRIAL
COMMERCIAL CONSUMER ISES
EXPOSURE PATHWAYS
POPULATIONS
EXPOSED
1084
1085
1086
1087
Figure 1-6. Asbestos Conceptual Model for Environmental Releases and Wastes: Ecological Exposures and Hazards
" Industrial wastewater or liquid wastes may be treated on-site and then released to surface water (direct discharge), or pre-treated and released to POTW
(indirect discharge). For consumer uses, such wastes may be released directly to POTW (i.e., down the drain).
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1.1.3 Populations Assessed
Based on the conceptual models presented in Section 1.1.2.1, Figure 1-7 presents the human and
ecological populations assessed in this Risk Evaluation. Specifically for humans, EPA evaluated risk via
inhalation route to workers and ONUs; to do-it-yourself consumers and bystanders; and to the general
population from environmental releases, disposals, and take-home exposures. After a thorough and
comprehensive investigation of the reasonably available evidence on the hazards and risks associated
with asbestos, the epidemiological studies continue to show that asbestos exposure is associated with
lung cancer, mesothelioma, laryngeal cancer and ovarian cancer (Section 5). Thus, the EPA determined
that the human health hazards identified in its previous reports as well as those from other agencies are
still relevant and valid. The White Paper further summarizes the human health approach taken for Part 2
(U.S. EPA. 2023oY
For environmental populations, EPA evaluated potential risk to aquatic species via water and sediment,
and risk to terrestrial species via inhalation exposure routes. Environmental risks were evaluated for
acute and chronic exposure scenarios, as applicable based on reasonably available exposure and hazard
data as well as the relevant populations for each.
Figure 1-7. Exposures and Populations Assessed in this Risk Evaluation
1.1.3.1 Potentially Exposed or Susceptible Subpopulations
TSCA requires that risk evaluations "determine whether a chemical substance presents an unreasonable
risk of injury to health or the environment, without consideration of costs or other non-risk factors,
including an unreasonable risk to a potentially exposed or susceptible subpopulation identified as
relevant to the risk evaluation by the Administrator, under the conditions of use." TSCA § 3(12) states
that "the term 'potentially exposed or susceptible subpopulation'' means a group of individuals within
the general population identified by the Administrator who, due to either greater susceptibility or greater
exposure, may be at greater risk than the general population of adverse health effects from exposure to a
chemical substance or mixture, such as infants, children, pregnant women, workers, or the elderly."
This risk evaluation considers potentially exposed or susceptible subpopulations (PESS) throughout the
human health risk assessment (Section 5). Considerations related to PESS can influence the selection of
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relevant exposure pathways, the sensitivity of derived hazard values, the inclusion of particular
subpopulations, and the discussion of uncertainties throughout the assessment.
1.2 Systematic Review
The U.S. EPA's Office of Pollution Prevention and Toxics (EPA/OPPT) applies systematic review
principles in the development of risk evaluations under the amended TSCA. TSCA section 26(h)
requires EPA to use scientific information, technical procedures, measures, methods, protocols,
methodologies, and models consistent with the best available science and base decisions under section 6
on the weight of scientific evidence. Within the TSCA risk evaluation context, the weight of the
scientific evidence is defined as "a systematic review method, applied in a manner suited to the nature of
the evidence or decision, that uses a pre-established protocol to comprehensively, objectively,
transparently, and consistently identify and evaluate each stream of evidence, including strengths,
limitations, and relevance of each study and to integrate evidence as necessary and appropriate based
upon strengths, limitations, and relevance" (40 CFR 702.33).
Systematic review supports the risk evaluation in that data searching, screening, evaluation, extraction,
and evidence integration and is used to develop the exposure and hazard assessments based on
reasonably available information. EPA defines "reasonably available information" to mean information
that EPA possesses or can reasonably obtain and synthesize for use in risk evaluations, considering the
deadlines for completing the evaluation (40 CFR 702.33).
In response to comments received by the National Academies of Sciences, Engineering, and Medicine
(NASEM), TSCA Scientific Advisory Committee on Chemicals (SACC) and public, EPA developed the
Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances (U.S.
EPA. 2021) (hereinafter referred to as "2021 Draft Systematic Review Protocol") to describe systematic
review approaches implemented in TSCA risk evaluations. In response to recommendations for
chemical specific systematic review protocols, the Draft Risk Evaluation for Asbestos Part 2 -
Systematic Review Protocol (U.S. EPA. 2023n) (also referred to as the "Asbestos Part 2 Systematic
Review Protocol") describes clarifications and updates to approaches outlined in the 2021 Draft
Systematic Review Protocol that reflect NASEM, SACC and public comments as well as chemical-
specific risk evaluation needs. For example, EPA has updated the data quality evaluation process and
will not implement quantitative methodologies to determine both metric and overall data or information
source data quality determinations. Screening decision terminology (e.g., "met screening criteria" as
opposed to "include") was also updated for greater consistency and transparency and to more
appropriately describe when information within a given data source met discipline-specific title and
abstract or full-text screening criteria. Additional updates and clarifications relevant for Asbestos Part 2
data sources are described in greater detail in the Asbestos Part 2 Systematic Review Protocol (U.S.
EPA. 2023nY
The systematic review process is briefly described in Figure 1-8, below. Additional details regarding
these steps are available in the 2021 Draft Systematic Review Protocol (U.S. EPA. 2021). Literature
inventory trees for each discipline (e.g., human health hazard) displaying results of the literature search
and screening, as well as sections summarizing data evaluation, extraction, and evidence integration are
included in the Asbestos Part 2 Systematic Review Protocol (U.S. EPA. 2023n).
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• Based on the
approach
described in the
Literature
Search Strategy
documents.
• Title/abstractand
full-text screening
based on pre-
defined
inclusion/exclusion
criteria.
• Evaluateand
document the
quality of studies
based on pre-
defined criteria.
Data Search
~
Data Screen
¦Jg)
Data
Evaluation
~ —
~ —
~ —
~ —
• Extract relevant
information based
on pre-defined
templates.
Data
Extraction
=1
1
• Evaluate results
both within and
across evidence
streams to develop
weight of the
scientific evidence
conclusions.
Evidence
Integration
|A
Figure 1-8. Diagram of the Systematic Review Process
EPA also conducted a search of existing major domestic and international laws, regulations and
assessments pertaining to asbestos. The Agency compiled this summary information from available
federal, state, international, and other government data sources Appendix B. EPA also identified key
assessments conducted by other EPA programs and other U.S. and international organizations.
Depending on the source, these assessments may include information on conditions of use (or the
equivalent), hazards, exposures, and potentially exposed or susceptible subpopulations (PESS). Some of
the most recent and pertinent assessments that were consulted include the following: U.S. EPA (2014c).
U.S. EPA (1988b). U.S. EPA (1989). and CPSC (1977V
1.3 Organization of the Risk Evaluation
This draft Part 2 risk evaluation for asbestos includes five additional major sections, a list of references,
and several appendices. Section 2 summarizes basic physical and chemical characteristics as well as the
fate and transport of asbestos. Section 3 includes an overview of releases and concentrations of asbestos
in the environment. Section 4 provides a discussion and analysis of the environmental risk assessment—
including the environmental exposure, hazard, and risk characterization based on the conditions of use
for asbestos. Section 5 presents the human health risk assessment, including the exposure, hazard, and
risk characterization based on the conditions of use. Section 5 also includes a discussion of PESS based
on both greater exposure and susceptibility, as well as a description of aggregate and sentinel exposures.
Sections 4 and 5 both discuss any assumptions and uncertainties and how they impact the asbestos risk
evaluation. Finally, Section 6 presents EPA's proposed determination of whether the chemical presents
an unreasonable risk under the COUs.
Appendix A includes the abbreviations, acronyms, and terminology used within the document and
appendices as well as a Appendix A.2. Appendix B summarizes the details of asbestos regulatory and
assessment history. Appendix C provides a list of supplemental documents such as spreadsheets and risk
calculators. All subsequent appendices include more detailed analysis and discussion than are provided
in the main body of this draft Part 2 risk evaluation for asbestos.
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2 CHEMISTRY AND FATE AND TRANSPORT OF ASBESTOS
Physical and chemical properties determine the behavior and characteristics of a chemical that inform its
condition of use, environmental fate and transport, potential toxicity, exposure pathways, routes, and
hazards. Environmental fate and transport includes environmental partitioning, accumulation,
degradation, and transformation processes. Environmental transport is the movement of the chemical
within and between environmental media, such as suspension and deposition of asbestos fibers. Thus,
understanding the environmental fate of asbestos informs the specific exposure pathways, and potential
human and environmental exposed populations that EPA considered in this Part 2 of the risk evaluation.
Asbestos - Chemistry and Fate and Transport (Section 2):
Key Points
EPA considered all reasonably available information identified by the Agency through its
systematic review process under TSCA to characterize the chemistry and fate and transport of
asbestos fibers. The following bullets summarize the key points of this section:
• The strong Si-O-Si covalent bonds found within the silicate tetrahedra of asbestos fibers are
responsible for its inherent environmental stability, negligible water solubility, high tensile
strength, hardness, and inherent chemical inertness.
• Small asbestos fibers (<1 (j,m) can remain suspended in air and water and their deposition is
expected to be higher closer to the asbestos source and eventually settle to soils, water
bodies, and sediments.
• When in water, asbestos fibers will eventually settle into sediments and biosolids from
wastewater treatment processes.
• Uptake of asbestos fibers is not expected in terrestrial and aquatic organisms, under normal
environmental conditions.
• Incineration of asbestos fibers will result in morphological changes during recrystallization
yielding non-asbestos fibers and negligible releases to air.
2.1 Physical and Chemical Properties
EPA gathered and evaluated physical and chemical property data and information according to the
process described in the Asbestos Part 2 Systematic Review Protocol. During the evaluation of Asbestos
EPA considered both measured and estimated property data/information set forth in Table 2-1, as
applicable.
Asbestos is a generic commercial designation for a group of naturally occurring mineral silicate fibers
of the serpentine and amphibole series (I ARC, 2012b). The Chemical Abstracts Service (CAS)
definition of asbestos is a grayish, non-combustible fibrous material. It consists primarily of impure
magnesium silicate minerals. Under TSCA for risk evaluation, EPA initially adopted the TSCA Title II
definition of asbestos (added to TSCA in 1986), as the asbestiform varieties of six fiber types -
chrysotile (serpentine), crocidolite (riebeckite), amosite (cummingtonite-grunerite), anthophyllite,
tremolite or actinolite. The latter five fiber types are amphiboles, while chrysotile is of the serpentine
class. The Part 1 Risk Evaluation focused on chrysotile, which is the only asbestos fiber with ongoing
use. Part 2 focuses on other fiber types, including LAA. Table 2-1 shows the physical and chemical
properties for the six asbestos fiber types, as well as LAA. LAA is a mixture of amphibole fibers
identified in the Rainy Creek complex and present in ore from the vermiculite mine near Libby,
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Montana (U.S. EPA. 2014c). These fiber types are hydrated magnesium silicate minerals with relatively
long crystalline fibers.
In general, amphibole asbestos fibers have less surface area, and are more brittle and inflexible than
serpentine asbestos fibers (Badollet. 1951). Asbestos fibers used in most commercial applications
consist of aggregates and usually contain a broad distribution of fiber lengths. Amphibole asbestos fiber
bundle lengths usually range from a fraction of a millimeter to several centimeters, and diameters range
from 0.1 to 1.4 ^m (NLM. 2021; U.S. EPA. 2014c: Hwang. 1983; Le Bouffant. 1980).
The variations between serpentine and amphibole asbestos fiber types are likely due to differences in
their chemical compositions, leading to differences in microcrystalline surface structure. The amphibole
asbestos fiber types can be better understood as being a series of minerals in which cations are
progressively replaced (Na, Mg, replaced by Fe) ("Virta. 2004). Amphibole asbestos fibers exhibit
surface charges either less than -20 mV, or greater than 24 mV indicating at least moderately stable
suspensions in water, however, more filamentous fiber types exhibit zeta potentials ranging further from
0 as those stated above, indicating a tendency for more stable suspension ("Virta. 2004; Schiller and
Payne. 1980). These differences in surface charge are due to the substitution of Mg and Ca ions with
divalent Fe at varying ratios in the mineral assemblage. Amphibole asbestos fibers are insoluble in both
water and organic solvents but do tend to form stable suspensions in water. The fibers do not appear to
undergo physical or chemical changes due to hydrolysis or photolysis but can undergo morphological
changes due to weathering and extreme conditions as described in Section 2.2.2.
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1238 Table 2-1. Physical and Chemical Properties of Asbestos Fiber Type
Property
Chrysotile
Crocidolite
Amosite
Anthophyllite
Tremolite
Actinolite
Libby Amphibole
Essential
Composition
Silica sheet (Si;Os).
with a layer of
brucite (Mg(OH)2)
with every 3
hydroxyls replaced
by oxygens11'
Na, Fe silicate with
some water15'
Fe, Mg silicate (5'
Magnesium and
iron silicates 111'
Ca, Mg silicate
with some water
(51
Ca, Mg, Fe silicate
with some water15'
Winchite (84%),
richterite (11%),
and tremolite (6%).
(16)
Color
Usually white to
grayish green, may
have tan coloring11'
Lavender, blue,
greenish15'
Ash gray, greenish,
or brown15'
Grayish white,
brown-gray, or
green15'
White to light-
green111'
Greenish15'
Luster
Silky11'
Silky to dull15'
Vitreous to pearly
(51
Vitreous to
pearly 15'
Silky 15'
Silky, greasy to
vitreous (5Hl7>
-
Surface Area (m2/g)
13.5 to 22.4121
4.62 to 14.80121
2.25 to 7.10 121
4.4 to 14.4 1121
0.66 to 9.2 1121
-
1.1 to 7.4 1161
Individual Fiber
Diameter (jim)
0.02 to 0.03111
0.09(7'
(Median true
diameter)
0.26 (median true
diameter)17'
<0.10 to 1.4 1131
0.2 to 0.42 1161
0.61 ± 1.22 1161
Average fiber outer
diameter (A)
200111
-
-
—
—
-
-
Particle Dimension
(Aim)
Largest Dimension
(L)
Smallest Dimension
(S)
Aspect Ratio L/S
(L): 1.00 ±0.44
(S): 0.07 ±0.02
L/S: 13.8 ±5.1131
(L): 5.33 ± 2.77 nm;
(S): 0.248 ± 1.60 jim;
L/S: 21.478 ±2.667181
(L): 4.63 nm;
(S): 0.258 nm;
L/S: 17.99 ll,:"
(L): 0.8 to 36.0
(S): 0.2 to 12.0 nm;
L/S: 3 to 4 1181
(L): 0.220 to
23.598 (1.95 mean)
(S): 0.0244 to 2.593
(0.316 mean)
(L/S): 1.0 to 128.9
(7.1 mean)(21"
Hardness (Mohs)
2.5 to 4.0111
4.0(6'
5.5 to 6.0 161
5.5 to 6.0 151
5 to 6 111'
6.0 151
-
Density (g/mL)
2.19 to 2.68141
3.2 to 3.3 161
3.1 to 3.25 161
3.09 041
2.9 to 3.2 161
2.9 to 3.11191
-
Optical Properties
Biaxial positive
parallel extinction
in
Biaxial negative
oblique extinction16'
Biaxial positive
parallel extinction
(6)
Biaxial positive
extinction
parallel15'
Biaxial negative
oblique
extinction16'
Biaxial negative
extinction inclined
(51
Refractive Index
1.53 to 1.56111
1.654 to 1.7 01(9'
1.635 to 1.696 191
1.596 to 1.652 191
1.599 to 1.668 191
1.599 to 1.668 191
-
Flexibility
High11'
Fair to Good(5'
Good15'
Poor (very brittle,
non-flexible)15'
Poor, generally
brittle,
sometimes
flexible 15'
Poor, brittle, and
non-flexible 15'
Texture
Silky, soft to harsh
in
Soft to harsh15'
Coarse, but
somewhat pliable 15'
Harsh15'
Generally harsh,
sometimes soft
(51
Harsh15'
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Property
Chrysotile
Crocidolite
Amosite
Anthophyllite
Tremolite
Actinolite
Libby Amphibole
Spinnability
Very good15'
Fair15'
Fair15'
Poor15'
Generally poor,
some are
spinnable 15'
Poor15'
Tensile Strength
1,100 to 4,400111
1,400 to 4,600 161
1,500 to 2,600 161
<30 (5'
<500 (6'
<7 I5'
-
(MPa)
Resistance to: Acids
Weak, undergoes
Fair
Fair, slowly
Fair
Resistance to
Fair
-
Bases
fairly rapid attack
Very good15'
Good15'
attacked
Good15'
Very good15'
acids: fair
Resistance to
bases: good15'
Fair15'
Zeta Potential (mV)
+13.6 to+54161
-32 (6'
-20 to -40 161
blocky particles =
39+2 and
elongated
particles = 49+2
at pH 7 (15'
blocky particles
= 24+1 and
elongated
particles = 35+3
at pH 7 (15'
Decomposition
600 to 850161
400 to 900 161
600 to 900 161
1,150 to 1,340 1141
950 to 1,040 161
1,140 to 1,296 °C
-
Temperature (°C)
(19)
Notes: source: overall data aualitv determination 7 = (Hwang. 1983); High
1 = (NLM. 2021); High 8 = (Siegrist and Wvlie. 1980); High
2 = (Addison et al.. 1966); Medium 9 = (Lott. 1989); High
3 = (Thorne et al.. 1985); High 10 = (Snvder et al.. 1987); High
4 = (Elsevier. 2021c): High 11 = (Larranaga et al.. 2016); High
5 = (Badollet. 1951); High 12 = (Pollastri et al.. 2014); High
6 = (Virta. 2004); High 13 = (Le Bouffant. 1980); High
14 = (Elsevier. 2021b): High
15 = (Schiller and Pavne. 1980); High
16 = (U.S. EPA. 2014c): High
17 = (Zhong et al.. 2019); High
18 = (Virta et al.. 1983): High
19 = (Elsevier. 2021a): High
20 = (Lowers and Bern. 2009). High
1239
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2.2 Environmental Fate and Transport
2.2.1 Fate and Transport Approach and Methodology
Reasonably available environmental fate data, including fiber dissolution in water, bioconcentration,
biodegradation rates, removal during wastewater and drinking water treatment, suspension and
resuspension, and incineration are among selected parameters for consideration in the current risk
evaluation. In assessing the environmental fate and transport of asbestos, EPA considered the full range
of results from sources that were rated as high and medium confidence. Information on the full data
quality evaluation and data extraction data set is available in the supplemental file Draft Risk Evaluation
for Asbestos Part 2 - Systematic Review Supplemental File: Data Quality Evaluation and Data
Extraction Information for Environmental Fate and Transport (U.S. EPA. 2023 d).
Table 2-2 provides selected environmental fate data that EPA considered while assessing the fate of
asbestos. The data in Table 2-2 were updated after publication of Final Scope of the Risk Evaluation for
Asbestos Part 2: Supplemental Evaluation Including Legacy Uses and Associated Disposals of Asbestos
(87 FR 38746) (EPA-HQ-2021-0254-0044) with additional information identified through the
systematic review process.
Table 2-2. Environmental Fate Properties of Asbestos
Property or
Endpoint
Value"
Reference
Overall Data
Quality
Determination
Aqueous
dissolution
Rate of dissolution is a function of surface area
and temperature. Mg2+ may be continuously
liberated from fibers leaving a silica skeleton.
Smaller particles liberated more magnesium.
Choi and Smith
(1972)
High
Air transport
Asbestos fibers of 0.1 to 1 um aerodynamic
diameters can be transported thousands of miles
in air.
ATSDR (2001)
Medium
Removal from
water with direct
filtration
Chrysotile asbestos; Mean removal: 90-99.89%
McGuire et al.
(1983)
High
Removal from
wastewater for
reuse application
Removal >99%
Water reuse with flocculation, filtration, reverse
osmosis, and disinfection
Lauer and
Converv (1988)
High
Removal in
surface water
Chrysotile asbestos;
Removal of fibers (%): >90% removal at
reservoirs with detention times >1 year
Reported removals:
Lake Silverwood: 27%; detention time 0.1 year
Lake Skinner: 88%; detention time 0.5 year
Lake Perris: 96%; detention time 1.5 years
Lake Pyramid-Castaic: 99.8%; detention time
3.0 years
Bales et al.
(1984)
Medium
Aerobic
biodegradation
Half-life in water >200 days
NICNAS (1999)
Medium
Bioconcentration
factor (BCF)
Asbestos fibers were found in the asbestos-
treated fish by transmission electron microscopy
(TEM). Sunfish lost scales and had epidermal
Belaneer et al.
(1986c)
High
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Property or
Endpoint
Value"
Reference
Overall Data
Quality
Determination
tissue erosion. Asbestos fibers were not
identified in control or blank samples.
Incineration
Incineration (combustion chamber target 850-
900 °C): Asbestos was not detected in solid
product or in exhaust gas; asbestos reduction
due to morphological changes.
Osada et al.
(2013)
High
11 Measured unless otherwise noted
2.2.2 Summary of Fate and Transport Assessment
Asbestos is a group of persistent and naturally occurring hydrated silicate mineral fibers that can be
found in soils, sediments, lofted in air and windblown dust, surface water, ground water and biota
(ATSDR. 2001) as depicted in Figure 2-1. The basic building block of asbestos fibers are silicate
tetrahedra in a variety of polymeric structures through formation of very strong Si-O-Si covalent bonds
and cationic sites that are occupied by either magnesium (chrysotile asbestos) or a combination of
magnesium, iron, calcium, and/or sodium (amphibole asbestos). The strong Si-O-Si covalent bonds are
responsible of many chemical properties that makes asbestos very stable in most environmental
conditions, have high tensile strength and hardness, and its inherent chemical inertness. The ionic bonds
where metals attach within the crystal lattices in the main silicate chain of asbestos fibers are weaker
than covalent bonds, leading to metal leaching in aqueous media. Under extreme conditions (e.g., 50
mM oxalic acid) asbestos fibers have been reported to undergo minor morphological changes such as
changes in fiber length or leaching of cations from the surface of the crystal lattice (Favero-Longo et al..
2005; Gronow. 1987; Schreier et al.. 1987; Choi and Smith. 1972). In general, asbestos fibers do not
evaporate, significantly dissolve, burn, undergo significant reactions, or otherwise degrade in the
environment (ATSDR. 2001).
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Landfill disposal
Runoff
Leachate
Groundwater
Land applied biosolids
Deposition and wind
blown resuspension
Wastewater facility
Indirect/Direct discharge
Figure 2-1. Fate and Transport of Asbestos in the Environment"
" The diagram depicts the distribution (grey arrows) and transport (black arrows) of Asbestos in the environment.
The width of the arrow is a qualitative indication of the likelihood that the indicated partitioning will occur (i.e.,
wider arrows indicate more likely partitioning and dashed arrows negligible transport).
Despite the durability of asbestos fibers in the environment, the accumulation of asbestos fibers is not
generally observed in terrestrial and aquatic organisms (ATSDR, 2001). Limited studies are available on
the bioconcentration or bioaccumulation of asbestos in environmental organisms. In field studies,
exposure to high concentrations of chrysotile asbestos (104to 108 fibers/L) has been documented to
result in embedment of fibers into tissues in clams (Corbicula sp.) (Belanger et al.. 1990; Belanger et al..
1986c; Belanger et al.. 1986a. b). However, under controlled laboratory experiments, 30-day aqueous
exposure to 108 fibers/L ( I 05 f/cc) chrysotile asbestos resulted in negligible accumulation of fibers in
clams (Belanger et al.. 1987). However, high fiber burdens were reported in clams with a lifelong
asbestos exposure of 109 fibers/L (106 f/cc) (Belanger et al.. 1987). In general, asbestos fibers are not
expected to bioaccumulate within aquatic organisms under environmentally relevant conditions.
Asbestos fibers usually contain a broad distribution of fiber lengths. Small asbestos fibers (<1 urn)
remain suspended in air and water and their deposition is expected to be higher closer to the asbestos
source as described in Section 3.3.4. In surface water, the concentration of suspended asbestos fibers are
reported to decrease more than 99 percent in water reservoirs with hydraulic retention times greater than
1 year (Bales et al.. 1984). Storm events may increase the deposition and resuspension of asbestos fibers
(Schreier and Lavkulich. 2015). During water treatment processes, the use of coagulation and
flocculation treatment processes have been reported to remove 80 to 99 percent of asbestos fibers, with
higher removal rates reported with use of filtration treatment units (vebler et al.. 1989; Lauer and
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Convery. 1988; Bales et al.. 1984; McGuire et al.. 1983; Lawrence and Zimmermann. 1977; Schmitt et
al.. 1977; Lawrence and Zimmermann. 1976). As stated in the Risk Evaluation for Asbestos Part 1, once
in water it will eventually settle into sediments (or possibly be present in biosolids from wastewater
treatment processes) (U.S. EPA. 2020a).
The inherent insulation properties of asbestos fibers are related to the fiber's potential to undergo
dehydration and dehydroxylation as a function of temperature. For example, the thermal insulation
property of chrysotile is due to its capability to remain stable up to 550 °C via dehydration, then
dehydroxylation of the brucite layer that occurs from 550 to 750 °C followed by decomposition at 850
°C. Thermally decomposed chrysotile fibers recrystalizes at 800 to 850 °C as forsterite and silica (Virta.
2004). Recent studies have investigated the use of destructive treatment approaches such as incineration
as an alternative for the disposal of asbestos containing materials. The use of incineration and other
thermal treatments of asbestos containing materials have been reported to transform asbestos fibers into
non-asbestiform types during recrystallization with very low to non-detectable concentrations of
asbestos fibers released to air (Carneiro et al.. 2021; Obminski. 2021; Witek et al.. 2019; Osada et al..
2013; Porcu et al.. 2005; Jolicoeur and Duchesne. 1981).
Overall, asbestos may be released to the environment through industrial or commercial activities, such
as processing raw chrysotile asbestos, fabricating/processing asbestos containing products, or the lofting
of friable asbestos containing materials during use, disturbance and disposal of asbestos containing
materials.
A detailed summary of physical and chemical properties and a fate and transport assessment is available
in Appendix D and the fate assessment supplemental document.
2.2.3 Weight of Scientific Evidence Conclusions for Fate and Transport
2.2.3.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
Fate and Transport Assessment
During the data extraction and evaluation of data collected in the systematic review process, the results
from multiple high and medium-quality studies were selected for this risk evaluation to represent the
range of the identified environmental fate endpoints. The available information was measured under
field monitoring conditions or controlled laboratory experiments. These studies are subject to several
sources of variability including variability inherent in the methodology, inter-laboratory variability and
variability due to factors such as the temperature, pH ranges, and test substance concentrations. Because
of these factors, no single value is universally applicable. However, the weight of scientific evidence
shows asbestos fibers are expected to be very stable under most environmental conditions.
Given the similarity of results from multiple high and medium-quality studies, there is robust weight of
evidence about the dissolution and removal in water and the incineration of asbestos fibers. Asbestos
fibers are stable and persistent in water under normal environmental conditions. Once in water, asbestos
fibers are expected to settle into sediments and biosolids, thus aquatic or terrestrial organisms are
unlikely to be exposed to asbestos fibers suspended in water. Lastly, the thermal destruction of asbestos
results in morphological changes resulting in the formation of non-asbestos fibers (such as forsterite,
amorphous silica, and enstatite during the recrystallization process). In addition, very low to non-
detectable concentrations of asbestos fibers released to air have been reported during incineration
processes.
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1345 Due to the limited number of high and medium-quality studies there is moderate weight of evidence
1346 about the bioconcentration, biodegradation, and air transport of asbestos fibers. Overall, there is no
1347 evidence to suggest bioaccumulation in food webs (ATSDR. 2001). but it is very persistent under most
1348 environmental conditions (NICNAS. 1999). Furthermore, fiber deposition is expected to be greater
1349 closer to asbestos sources as described in Section 3.3.4.
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3 RELEASES AND CONCENTRATIONS OF ASBESTOS
3.1 Approach and Methodology
3.1.1 Industrial and Commercial
EPA categorized the COUs listed in Table 1-1 into occupational exposure scenarios (OESs) as shown in
Table 3-1. EPA developed the OESs to group processes or applications with similar sources of release
and occupational exposures that occur at industrial and commercial workplaces within the scope of the
risk evaluation. For each OES, occupational exposure and environmental release results are provided
and are expected to be representative of the entire population of workers and sites involved for the given
OES in the United States. In some cases, only a single OES is defined for multiple COUs, while in other
cases multiple OESs are developed for a single COU. This determination is made by considering
variability in release and use conditions and whether the variability can be captured as a distribution of
exposure or instead requires discrete scenarios. Further information on specific OESs is provided in
Appendix E.
Table 3-1. Crosswalk of Conditions of Use to Occupational Exposure Scenarios Assessed
Life Cycle
Stage"
Category6
Subcategoryc
Occupational Exposure
Scenario (OES)
Industrial/
Commercial Uses
Chemical Substances in
Construction, Paint,
Electrical, and Metal
Products
Construction and building
materials covering large surface
areas, including paper articles;
metal articles; stone, plaster,
cement, glass, and ceramic
articles
Handling asbestos-containing
building materials during
maintenance, renovation, and
demolition activities;
(Appendix E.10)
Handling of asbestos-
containing building materials
during firefighting or other
disaster response activities
(AppendixE.il)
Machinery, mechanical
appliances, electrical/electronic
articles
Other machinery, mechanical
appliances, electronic/electronic
articles
Use, repair, or removal of
industrial and commercial
appliances or machinery
containing asbestos
(Appendix E.12)
Electrical batteries and
accumulators
Solvent-based/water-based
paint
Fillers and putties
Handling articles or
formulations that contain
asbestos
(Appendix E.13)
Chemical Substances in
Furnishing, Cleaning,
Treatment Care Products
Construction and building
materials covering large surface
areas, including fabrics, textiles,
and apparel
Handling asbestos-containing
building materials during
maintenance, renovation, and
demolition activities;
(Appendix E.10)
Handling of asbestos-
containing building materials
during firefighting or other
disaster response activities
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Life Cycle
Stage"
Category6
Subcategoryc
Occupational Exposure
Scenario (OES)
Industrial/
Commercial Uses
(AppendixE.il)
Furniture & furnishings
including stone, plaster, cement,
glass, and ceramic articles;
metal articles; or rubber articles
Handling articles or
formulations that contain
asbestos (Appendix E.13)
Chemical Substances in
Packaging, Paper,
Packaging (excluding food
packaging), including rubber
articles; plastic articles (hard);
plastic articles (soft)
Handling articles or
formulations that contain
asbestos
(Appendix E.13)
Chemical Substances in
Products not Described by
Other Codes
Other (artifacts)
Other (aerospace applications)
Chemical Substances in
Automotive, Fuel,
Agriculture, Outdoor Use
Products
Lawn and garden products
(vermiculite soil treatment)
Handling of vermiculite-
containing products
(Appendix E.14)
Laboratory chemicals
Laboratory chemicals
(vermiculite packaging
products)
Mining of Non-Asbestos
Commodities
Mining of non-asbestos
commodities
Mining of non-asbestos
commodities
(Appendix E.15)
Disposal,
including
Distribution for
Disposal
Disposal, including
Distribution for Disposal
Disposal, including distribution
for disposal
Waste handling, disposal, and
treatment
(Appendix E.16)
"Life Cycle Stage Use Definitions (40 CFR 711.3)
- "Industrial use" means use at a site at which one or more chemicals or mixtures are manufactured (including
imported) or processed.
- "Commercial use" means the use of a chemical or a mixture containing a chemical (including as part of an
article) in a commercial enterprise providing saleable goods or services.
- "Consumer use" means the use of a chemical or a mixture containing a chemical (including as part of an
article, such as furniture or clothing) when sold to or made available to consumers for their use.
- Although EPA has identified both industrial and commercial uses here for purposes of distinguishing scenarios
in this document, the Agency interprets the authority over "any maimer or method of commercial use" under
TSCA section 6(a)(5) to reach both.
h These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly represent
conditions of use of asbestos in industrial and/or commercial settings.
c These subcategories reflect more specific conditions of use of asbestos.
3.1.1.1 General Approach and Methodology for Environmental Releases
For each OES, daily releases to air, land, and water were estimated based on annual releases, release
days, and the number of sites (Figure 3-1). The blue boxes represent primary sources of release data that
were used to develop annual releases, release days, and number of sites. The information in the green
boxes is aggregated by OES to provide daily release estimates. Generally, EPA used 2016 to 2020 TRI
(U.S. EPA. 2022a\ 2014 to 2017 National Emissions Inventory (NEI) (U.S. EPA. 2022d\ and 2015 to
2022 National Response Center (NRC. 2022) to estimate annual releases. Where available, EPA used
literature search data for estimation of associated release days. To estimate the number of sites using
asbestos within a condition of use, EPA relied on U.S. Census Bureau data, as well as literature search
data. Generally, information for reporting sites in NEI was sufficient to accurately characterize each
reporting site's condition of use. However, information for determining the condition of use for
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reporting sites in TRI is typically more limited. The approach and methodology for estimating daily
releases is described in Appendix E, which also includes detailed facility4evel results.
Figure 3-1. An Overview of How EPA Estimated Daily Releases for Each OES
TRI = Toxics Release Inventory; NEI = National Emissions Inventory; NRC = National
Response Center; NFPA = National Fire Protection Association
3.1.2 Take-Home
Workers performing job-related activities (e.g., demolition and asbestos removal) that expose them to
asbestos fibers can transfer asbestos fibers from the working environment to the home environment via
contaminated clothes or surfaces. This creates the potential for take-home exposures. Demolition and
asbestos removal workers go to great lengths to avoid asbestos exposure to themselves, those around
them, and the environment when they follow National Emission Standards for Hazardous Air Pollutants
(NESHAP) rules and regulations, 40 CFR Part 61, subpart M. However, take-home exposures from
contaminated clothes/surfaces can occur when asbestos is not handled following NESHAP guidance or
when personal protective equipment (PPE, protective clothing) is unavailable. This section summarizes
take-home exposures scenarios and the data and methods used to evaluate scenarios not following
NESHAP.
3.1.2.1 Methods and Key Assumptions to Determine Asbestos Concentrations
Figure 3-2 provides a diagram of the mechanism of exposure for the take-home scenario. On the left, the
diagram depicts an occupational worker on three consecutive days of work, where each day the worker
is exposed to the same 8-hour time-weighted average (TWA) asbestos concentration. In addition to their
inhalation exposure during the workday, the fibers may settle onto the clothing worn by the worker,
referred to as the "occupational loading." This fiber loading dictates the quantity of asbestos available
for resuspension at home during laundry preparation. Although current Occupational Safety and Health
Administration (OSHA) regulations (29 CFR 1926.1101) prohibit taking contaminated clothing home,
this exposure pathway was included to account for workers who may not follow all OSHA guidelines
and incur in exposures due to lack of knowledge about asbestos identification, removal, handling, and
disposal of contaminated clothes or a personal choice. Thus, on the right, when the clothing worn on
those three days is prepared for laundering, shaking/folding/unfolding the clothes will tend to resuspend
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a fraction of the loaded fibers into the residential indoor air, resulting in inhalation exposure for the
clothes handler and any bystanders.
Day 1
Occ. Concen.
Workplace Exposure
Day 2
Occ. Concen.
— Airborne asbestos fibers in the occupational setting
— Deposited fibers on the worker's clothing
— Airborne asbestos fibers in the take-home setting
Day 3 ...
Occ. Concen.
# Take-home Exposure
Washing Event
Take Home Concen. per garment x 3 garments
ft / /
Laundry prep
releases fibers
to air
mwiti
Handler
Bystander
Figure 3-2. Take-Home Scenario Mechanism of Exposure
In considering the take-home scenarios, exposures across days could happen in many ways depending
on the number of work garment sets worn, the pattern of workdays when asbestos exposure occurs, the
frequency of washing events, and the number of garment sets per washing event. For example, (1) a
worker may wear one garment set for three consecutive days and then launder, or (2) a worker may wear
a different garment set each day and launder all three together (see Figure 3-2). Because the
occupational concentrations and take-home concentrations are linked via the occupational loading
process, EPA defined a "unit" of take-home exposure, as depicted in Figure 3-3.
^ * ' +. f
/ \ / N /
c ^ r...
Airborne
fibers
deposit or
clothes
inhal.
Occ. ,
Loading
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Key Assumption: Unit Exposure for Take-Home Scenarios
one occupational exposure day corres onds to one ,a^e'^ome exposure day
where a single garment is loaded where a single garment is washed
based on an 8-hr TWA conc. leading to a proportional '4-hr TWA conc.
For one day of workplace exposure:
24-hr TWA
Take Home Concen.
%
/ /
k
Figure 3-3. Take-Home Exposure Scenarios Key Assumptions Summary
This approach assumes all garment sets are ultimately washed, and one unit is 1 day of loading at the 8-
hour TWA concentration. Then, the 24-hour TWA take-home concentration when that garment is
washed is given by an empirically derived "take-home slope factor" (second term in Equation 3-1). The
empirical data to derive the take-home slope factor are described in Section 3.1.2.2 and Table 3-2. In
this proposed approach, a specific scenario where the actual 8-hour TWA concentration is "[X] f/cc"
(first term in Equation 3-1) results in a 24-hour take-home exposure concentration of [7] multiplied by
the take-home slope factor. The intercept should be zero because if there is no occupational fibers
loading then there is no take-home exposure.
Equation 3-1. Equation to Calculate Take-Home Exposures 24-Hour TWA Concentrations
24hr TWA Concentration = 8hr TWA Concentration x Take home slope factor + Intercept
24hr TWA Concentration [7]
Take home slope factor = —-
8hr TWA Concentration [Z]
3.1.2.2 Data Sources and the Take-Home Slope Factor Estimation
The 8-hour TWA occupational exposure concentration [X] and 24-hour TWA take-home exposure
concentration [Y] are data taken from the identified studies. The take-home slope factor uses studies that
jointly monitor the workplace exposure and subsequent handling of asbestos-contaminated clothing
("take-home studies") and represents the ratio between (1) the 24-hour TWA take-home exposure
concentrations during laundry preparation activities (Equation 3-1, numerator), and (2) the 8-hour TWA
occupational exposure concentrations during the loading period (Equation 3-1, denominator).
To select these studies, all experimental, monitoring, and/or modeling studies with a low, medium, or
high overall quality determination were examined for applicability using the following criteria:
• Keyword: Title or abstract mention "take-home" exposures
8-hr TWA
Occ. Concen. ^
^ H ' w ^
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• Scenario: Asbestos fibers released from clothing or other items brought home from the work site
during routine handling of clothes.
• Country: United States or Canada
• Timeframe: Sampling conducted since 2000, although prior years are considered given limited
availability of data
• Media Type: Indoor air or personal inhalation
• Microenvironment: Living area of houses (test houses or simulated via experimental chambers)
• Analytical Method/Units: PCM or TEM measured as fibers/cc
Following application of these criteria, eight experimental studies were selected for further review; one
study, upon further full-text review, was excluded, leaving seven studies for use in determining the take-
home slope factor. The included studies were selected because they represent occupational loading to
clothing and subsequent handling of that garment. EPA use this data as a proxy for workers that unaware
of asbestos presence or health effects bring those garments home, if the workers follow the existing
guidelines take-home exposures would likely not happen. The excluded study, Weir et al. (2001). was
not considered representative of residential clothes handling scenarios because they used small 150 L
dynamic flow chambers in the experiments. There is high uncertainty in how representative the
experimental method (small chamber) is to real-world samples collected via personal breathing zone or
area samples. Table 3-2 and Table Apx J-l in Appendix J provide the study activity type, job-related
loading event information, take-home exposure event information, and sampling details of the seven
studies. Table 3-2 also summarizes the measured levels of asbestos during the loading and take-home
clothes preparation used in the regression analysis. Calculations and slope factor approaches are
available in Asbestos Part 2 Draft RE - Risk Calculator for Take Home - Spring 2023 (U.S. EPA.
2023m) (see also Appendix C).
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1467
Study
Analytical
Method
Event Duration
(min)
Number of
Garments
per
Loading
Event
Concen-
8-hr TWA
Avg. Loading
Event
Avg. Take-Home Event
Concentration (f/cc)
24-hr TWA Take-Home Event
Concentration Normalized to
One Garment (f/cc)
Load"
Handler6
Handler
Event
tration
(f/cc)
Concen-
tration (f/cc)
Handler
Bystander
Handler
Bystander
Abelmann et al.
(2017)
PCM
30
30
2
8.8E01
5.50E-01
5.20E-01
3.40E-01
5.42E-03
3.54E-03
Madletal. (2014)
PCME
30
30
6
1.3E-02
8.13E-04
5.00E-03
1.50E-03
1.74E-05
5.21E-06
Madl et al. (2009)
PCME
30
30
11
2.4E-02
1.50E-03
3.60E-02
1.00E-02
6.82E-05
1.89E-05
Madl et al. (2008)
PCME
30
15
3
1.98E-01
1.24E-02
1.10E-02
1.00E-02
3.82E-05
3.47E-05
Jiang et al. (2008)
PCME
30
15
3
1.19E-01
7.44E-03
3.00E-03
2.00E-03
1.04E-05
6.94E-06
Sahmel et al.
(2014) Low
15
5.0E-02
3.13E-03
7.00E-03
1.00E-03
1.22E-05
3.47E-06
Sahmel et al.
(2014) Medium
PCME
30
handler,
30
6
2.235E00
1.40E-01
9.40E-02
3.75E-03
1.63E-04
1.30E-05
Sahmel et al.
(2014) Hieh
bystander
3.125E00
1.95E-01
1.29E-01
9.50E-03
2.24E-04
3.30E-05
Sahmel et al.
(2016)
PCME
390
15
handler,
45
bystander
3
1.14E01
9.26E00
2.94E00
6.20E-01
1.02E-02
6.46E-03
" Load refers to occupational loading that is the fibers that settle onto the clothing worn by the worker. This fiber loading dictates the quantity of asbestos available for
resuspension at home during laundry preparation. In this case, extent of occupational activity duration.
b Refers to amount of time in minutes the handler of clothing handled the clothing, which can include activities like undressing, shaking, and folding
PCM = phase contrast microscopy; PCME = PCM-equivalent
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Using the 8-hour TWA loading event concentrations in Table 3-2 as the independent variable and the
24-hour TWA take-home concentrations as the dependent variable, linear regression slopes (the take-
home slope factor), intercepts, and R2 were estimated in three different ways:
• Included in this risk evaluation all 7 studies in a single regression;
• Included Abelmann et al. (2017). Madl et al. (2014). and Madl et al. (2009) together; and
• Included Madl et al. (2008). Jiang et al. (2008). Sahmel et al. (2014). and Sahmel et al. (2016)
together; the three different target loading concentrations in Sahmel et al. (2014) were treated as
three different points in the regression.
Table 3-3 presents the results from this analysis and Figure 3-4 regression analysis makes clear that the
different studies cluster into two different take-home slope factors, where Abelmann et al. (2017). Madl
et al. (2014). and Madl et al. (2009) give a slope factor of approximately 0.0098 for handlers while Madl
et al. (2008). Jiang et al. (2008). Sahmel et al. (2014). and Sahmel et al. (2016) give a slope factor of
0.0011 for handlers. The factor in Regression 3 is roughly an order of magnitude lower than in
Regression 2 and generally in line with the conclusion in Sahmel et al. (2014) and Sahmel et al. (2016)
that the 8-hour TWA take-home concentrations are about 1 percent of the 8-hour TWA loading
concentrations. Both Regression 2 and 3 have R2 near 1, and no specific study experimental set-up or
method descriptions indicated why the two groups of studies cluster into two distinct groups. Without
additional information to indicate which studies may provide the best experiments from which to
estimate these slope factors, the two groups were used to determine a central tendency (CT) and high-
end (HE) take-home slope factor:
• CT Slope Factor, Regression 3
o Handler: 0.0011; bystander: 0.00070
• HE Slope Factor, Regression 2
o Handler: 0.0098; bystander 0.0064
Table 3-3. Regression Coefficients for Three Regression Equations
Regression
Handler Regression
Bystander Regression
Slope
Intercept
R2
Slope
Intercept
R2
Regression 1, All Studies
0.0011
0
0.8059
0.00067
0
0.7916
Regression 2, 3 Studies, "HE"
0.0098
0
0.9999
0.0064
0
0.9999
Regression 3, 4 Studies, "CT"
0.0011
0
1.0000
0.00070
0
0.9995
24-hour TWA take-home concentration as a function of 8-hour TWA loading concentration
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3
| 1E-4
O
X
l
M 1E-5
4
Handler CT Per Garment 24-Hr Avg Concentration as a Function of Occ 8-hr
H
M
= 0.0098X
= 0.9999
y = O.OOllx
R2 = 1
•
•
A..-"
* /
glE-3
U
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Table 3-4. Qualitative Assessment of the Uncertainty and Variability Associated with
Concentration Data Used in Take-Home Exposure Analysis
Variable Name
Effect
Uncertainty
(L, M, H) «
Variability
(L, M, H) «
Asbestos fiber sizes
Concentration data used may include smaller particle
sizes and hence overestimate risk.
H
H
Overall sample analysis
method such as TEM,
PCM, and PCME
Methods may include non-asbestos fiber concentrations
and overestimate risk. Most studies used PCME to
confirm asbestos fibers.
M
M
Simulations of fiber
releases during an activity
Increase uncertainty and variability because products and
asbestos concentrations vary for different activities and
asbestos containing products.
H
H
Sampling time
Similar sampling times decreases variability and
uncertainty as these were representative of usual
occupational activity durations.
L
L
One garment per loading
approximation
Decreases complexity so results can be used for all take-
home and working scenarios.
M
M
Overall take-home
concentration data
Concentrations used in risk calculation estimates.
M
H6
"L = low; M = moderate; H = high
h Low-end to high-end concentration ranges 3-4 orders of magnitude difference
PCM = phase contrast microscopy; PCME = PCM-equivalent; TEM = transmission electron microscopy
3.1.3 Consumer
The consumer COUs include categories related to chemical substances in
• Construction, paint, electrical, and metal products;
• Furnishing, cleaning, treatment care products;
• Packaging, paper, plastic, toys, hobby products;
• Automotive, fuel, agriculture, outdoor use products; and
• Products not described by other codes.
Specifically, these categories are associated with subcategories and specific product examples, as shown
in Table 1-1. These product examples are no longer manufactured or available for purchase; however,
asbestos is still found in a variety of consumer and commercial products that remain in use. The
consumer scenarios in this evaluation are for legacy uses in which all scenarios are task- or activity-
based DIY scenarios in which the user is not a professional nor acting in a professional setting. They
perform an activity involving an asbestos product that modifies the product leading to the release of
asbestos fibers. Product modification can occur when it is disturbed/repaired (e.g., sanded, grinded,
drilled, scraped, cut, shoveled, or moved) or replaced; these activities may occur during normal home
maintenance and/or when users perform small or large renovations. These activities can release asbestos
fibers that can be inhaled.
Section 3.1.3.1 first reviews example products that may contain asbestos and be used in DIY activities
for the COU categories and subcategories. Then, in Section 3.1.3.2, the products that have the potential
to release asbestos are mapped to specific activity-based scenarios, where each product is generally
linked to both a "disturbance/repair" and "replacement" activity. Where possible, the releases and
exposures to users and bystanders (discussion in Section 3.1.3.3 with a summary of scenario
concentrations in Section 3.1.3.4) and associated risks are quantified (Section 5); for scenarios where
literature is not available to quantify exposure, risks are discussed qualitatively.
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3.1.3.1 Friable Asbestos Fibers in Products and Products Prioritized for Assessment
Section 3.1.3.1 outlines specific product examples containing friable asbestos for the different COU
categories and subcategories. The NESHAP for asbestos, 40 CFR part 61, subpart M defines "friable
asbestos material" as "any material containing more than 1 percent asbestos by weight *** that, when
dry, can be crumbled, pulverized, or reduced to powder by hand pressure." 40 CFR 61.141. Exposure to
asbestos fibers from the product examples depends on the potential release of fibers during intended use
or while performing some activity that modifies the product.
As described in the scope document, products containing friable asbestos were primarily identified from
three sources:
• Regulatory impact analysis of controls on asbestos and asbestos products: Final report: Volume
III (U.S. EPA. 1989):
• Review of asbestos use in consumer products (final report) (CPSC, 1977): and
• Sampling and analysis of consumer garden products that contain vermiculite (U.S. EPA. 2000a).
Through systematic review, additional papers were also identified for consumer uses that provided
specific product asbestos weight fractions. Table 3-5 summarizes the COU categories/subcategories,
product examples, and respective weight fractions. To assess friability, all identified products, other than
crayons, have upper weight fraction ranges above 1 percent; however, not all products are friable by
hand pressure. Generally, products containing asbestos will not release asbestos fibers unless the
materials are modified, as previously discussed (e.g., mechanical manipulations). However, it was
determined that construction materials are subject to activities that can release fibers under dry
conditions, such as sanding, cutting, and removal and hence are considered to have friable fibers. Fiber
friability for products that are subject to activities in which fibers are expected to become friable by
hand was assigned using expert personal opinions, for example, asbestos reinforced plastics are not
expected to crumble under hand pressure.
Table 3-5 includes a column that notes the "priority for evaluation for DIYers." All products that were
determined to be friable by hand are considered to be high priority. Products that have a "No" for hand
friability and a "Yes" for "sanding/cutting" friability where consumer DIYers are judged less likely to
perform sanding and cutting activities (compared with, for example, commercial workers working with
the products) are assigned a low priority (see footnote "j"). Examples include metal gaskets, cement,
electro-mechanical parts in appliances, and plastics used in appliances and toys. In addition, while some
products/articles are friable, any product with a lifetime less than 30 years is unlikely to remain in
current use, where 30 years reflects the fact that most products no longer used asbestos by the late 1980s
(U.S. EPA. 1989). EPA deprioritized products such as textiles, burner mats, wicks, and soil treatment
products on this basis (see footnote "k"). Remaining products with a "High" in the "Priority for
Consumer Exposure Evaluation" column in Table 3-5 are evaluated either qualitatively or quantitatively
in the consumer exposure assessment, as discussed in the next section.
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1592 Table 3-5. Conditions of Use, Product Examples, Weight Fractions, and Friable Fibers
cou
Subcategory
Product
Type
Product Examples
Weight Fraction -
Percent Asbestos by
Weight (%)
Friable by
Hand
Friable by
Sanding,
Cutting
Priority for
Consumer
Exposure
Evaluation
System. Review Data
with Evaluation
Rating
Exposure
Estimate Type
Chemical substances in construction, paint, electrical, and metal products COU
Construction and
building
materials
covering large
surface areas:
paper articles;
metal articles;
stone, plaster,
cement, glass,
and ceramic
articles
Paper
articles
Corrugated paper (for use
in pipe wrap insulation and
appliances)
95-98% °
Yes
Yes
High
None
Qualitative, H.l.l
Commercial papers,
millboard; rollboard;
specialty paper
Up to 90% b
Yes
Yes
High
None
Qualitative H.l.l
Metal
articles
Stove gaskets and rings,
fireplace embers, Galbestos
Up to 90% b
No
Yes
Low'
None
None
Stone,
plaster,
cement,
glass, and
ceramic
articles
Plaster and mastic
5-15%c
Yes
Yes
High
(Lanse et al.. 2008). M
Quantitative
H.l.l
Cement, corrugated
cement, cement pipes and
ducts (air, water, or sewer)
Air duct joint sealing
cement, 1-5%h
No
Yes
Low'
None
None
Cement pipe for
airduct, 10-20%b
No
Yes
Low'
None
None
Cement sheet,
15-45%° b
No
Yes
Low'
None
None
Cement pipe for
water, 10-25%h
No
Yes
Low'
None
None
Roofing
and siding
materials
Roofing felt
85-87%°
No
Yes
High
(Lanse et al.. 2008). M
Quantitative
H.l.l
Roofing cement
3-15%c
No
Yes
High
(Mowat et al.. 2007).
H;
(Lanse et al.. 2008). M
Quantitative
H.l.l
Roofing shingles
13-18%°
No
Yes
High
(Lanse et al.. 2008). M
Quantitative
H.l.l
Siding
13-18%°
No
Yes
High
(Lanse et al.. 2008). M
Quantitative
H.l.l
Ceiling
materials
Acoustical ceiling tiles
1-5%"
Yes
Yes
High
(Boelter et al.. 2016).
M;
(Lanse et al.. 1993). M
Quantitative
H.l.l
Flooring
materials
Flooring felt
Up to 85% °
No
Yes
High
None
Quantitative
H.l.l
Flooring tile (vinyl)
10-20% 6
No
Yes
High
(Lundsren et al..
1991). M
Quantitative
H.l.l
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cou
Subcategory
Product
Type
Product Examples
Weight Fraction -
Percent Asbestos by
Weight (%)
Friable by
Hand "
Friable by
Sanding,
Cutting
Priority for
Consumer
Exposure
Evaluation
System. Review Data
with Evaluation
Rating
Exposure
Estimate Type
Insulation
Loose-fill insulation
Unknown
Yes
Yes
High
(Ewine et al.. 2010).
M
Quantitative
H.l.l
Machinery,
mechanical
appliances,
electrical/
electronic articles
Plastics
Reinforced plastics for
appliances such as ovens,
dishwashers, boilers, and
toasters
17%°
No
Yes
Low'
None
None
Electro-
mechanical
parts
Miscellaneous electro-
mechanical parts for
appliances including deep
fryers, frying pans and
grills, mixers, popcorn
poppers, slow cookers,
refrigerators, curling irons,
electric blankets, portable
heaters, safes, safety boxes,
filing cabinets, and kilns
and incinerators
Appliance wiring, up
to 100%b
No
Yes
Low'
None
None
Slow cooker,
65-75% b
No
Yes
Low'
None
None
Toasters, 95%h
No
Yes
Low'
None
None
Hair dryers,
85-90% b
No
Yes
Low'
None
None
Refrigerators,
14-50%e
No
Yes
Low'
None
None
Washing machines,
8-20%e
No
Yes
Low'
None
None
Gas boiler, 2-25%e
No
Yes
Low'
None
None
Fillers and putties
Adhesives
Glues and epoxies
Up to 5%ah
No
Yes
Low'
None
None
Adhesives, mastics, and
cements to bond surfaces
such as brick, lumber,
mirror, and glass
1- 9% °f
No
Yes
Low'
(Paustcnbach et al..
2004), M
Quantitative
H.l.l
Sealants
Semi-liquid glazing and
caulking compounds
applied with a caulking gun
or putty knife, to seal
around glass in windows,
joints in metal ducts, and
bricks
0.5-25%
No
Yes
Low'
(Lanee et al.. 2008). M
Quantitative
H.l.l
Joint compound, patching,
spackling material
0.25-12%
Yes
Yes
High
(Rohl et al.. 1975). M
Quantitative
H.l.l
Liquid sealants used for
waterproofing and sound
deadening interior walls
1-5% a
No
Yes
Low'
None
None
Butyl rubber and vinyl
sealants applied over welds
1-5% af
No
Yes
Low'
(Paustcnbach et al..
2004). M
Quantitative
H.l.l
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cou
Subcategory
Product
Type
Product Examples
Weight Fraction -
Percent Asbestos by
Weight (%)
Friable by
Hand "
Friable by
Sanding,
Cutting
Priority for
Consumer
Exposure
Evaluation
System. Review Data
with Evaluation
Rating
Exposure
Estimate Type
for corrosion protection and
aesthetics
Extruded sealant tape used
Up to 20%"
No
Yes
Low'
None
None
Fillers and putties
as a gasket for sealing
building windows,
automotive windshields,
and mobile home windows
Coatings
Asphalt based coatings,
used to prevent decay and
corrosion of underground
pipes and structural steel
5-10% a-f
No
Yes
Low'
(Paustenbach et al..
2004), M
Quantitative
H.l.l
Vehicle undercoating to
5-30% b
No
Yes
Low'
None
None
prevent corrosion
Solvent-
based/water-
Coatings;
textured
Coatings; textured paints
1-5% b
Yes
Yes
High
(Sawver. 1977). L
None
based paint
paints
Chemical substances in furnishing, cleaning, treatment care products COU
Construction and
Asbestos
Wicks for oil burning
Up to 100% *
Yes
Yes
Low k
None
None
building
materials
textiles
including
covering large
surface areas.
yarn,
thread.
including fabrics,
textiles, and
apparel
wick, cord,
rope, tubing
(sleeving),
cloth, tape
Furniture and
Burner mats
85% b
Yes
Yes
Low k
None
None
furnishings,
including stone,
plaster, cement.
Fabrics,
textiles, and
apparel
glass, and
ceramic articles;
metal articles; or
rubber articles
Textiles and cloth
(including gloves and
mittens)
75-100% ab
Yes
Yes
Low k
(Cherrie et al.. 2005).
M
Quantitative
H.l.l
Chemical substances in packaging, paper, plastic, toys, hobby products COU
Packaging
(excluding food
Plastic
articles.
Asbestos reinforced plastics
(e.g., ashtrays)
20-25% *
No
Yes
Low'
None
None
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cou
Subcategory
Product
Type
Product Examples
Weight Fraction -
Percent Asbestos by
Weight (%)
Friable by
Hand "
Friable by
Sanding,
Cutting
Priority for
Consumer
Exposure
Evaluation
System. Review Data
with Evaluation
Rating
Exposure
Estimate Type
packaging),
including rubber
articles; plastic
articles (hard);
plastic articles
(soft)
Asbestos
reinforced
plastics
Child dedicated articles or
plastic articles (hard)
5-50% 6
No
Yes
Low'
None
None
Toys intended for
children's use
(and child
dedicated
articles),
including fabrics,
textiles, and
apparel; or plastic
articles (hard)
Toys
Mineral kits
Unknown
No
Yes
High
None
Quantitative
H.l.l
Crayons
0.03% h
Yes
Yes
High
(Saltzman and
Hatlelid. 2000). M
Quantitative
H.l.l
Chemical substances in automotive, fuel, agriculture, outdoor use products COU
Lawn and garden
care products
Lawn and
garden care
products
Venniculite soil treatment
0.1-3%'
Yes
Yes
Low k
(U.S. EPA. 2000a). H
Quantitative
H.l.l
Chemical substances in products not described by other codes COU
Chemical
Substances in
Products not
Described by
Other Codes
Vintage
artifacts in
private
collections;
vintage
cars,
articles,
curios
Metal dedener
10% *
No
Yes
Low
None
None
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cou
Subcategory
Product
Type
Product Examples
Weight Fraction -
Percent Asbestos by
Weight (%)
Friable by
Hand "
Friable by
Sanding,
Cutting
Priority for
Consumer
Exposure
Evaluation
System. Review Data
with Evaluation
Rating
Exposure
Estimate Type
1593
a (U.S. EPA. 1989)
b (CPSC. 1977)
c (Mowat et al.. 2007)
d (Boelter et al.. 2016)
e (Hwang and Park. 2016)
¦f (Paustenbach et al.. 2004)
g (Rohl et al.. 1975)
h (Saltzman and Hatlelid. 2000)
1 (U.S. EPA. 2000a)
¦' Limited exposures for DIY consumers because consumers are assumed to unlikely sand or cut materials
' Reduced exposure potential due to expected lifetime of product/article
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3.1.3.2 Activity-Based Scenarios and Data Sources
For prioritized products/articles in Table 3-5 that a consumer may encounter, EPA searched the
systematic review references tagged to identify experimental, monitoring or modeling studies that
measured asbestos fibers released during potential activity-based scenarios. The studies and data used in
this evaluation were selected for applicability using the following criteria:
• Keyword: Within articles screened at full-text, the title or abstract mention the targeted friable
consumer products listed in Table 3-5.
• Scenario: Asbestos fibers released from specific tasks or activities that a DIY user may perform.
Studies evaluating workers were included.
• Country: United States, Canada, and high-income foreign countries.
• Timeframe: Sampling conducted since 2000, although prior years are considered given limited
availability of data and most likely timeframe of use of asbestos-containing products.
• Media Type: Personal breathing zone data for a DIY user; indoor or outdoor area air data for a
bystander.
• Analytical Method/Units: PCM or TEM measured as fibers/cc with the identification of
asbestos fiber type and size within the scope of this evaluation (i.e., fibers >5 |im and 3:1 aspect
ratio).
Table 3-5 includes columns noting the relevant references for each product/article, including the study
quality evaluation rating: high ("H"), medium ("M"), or low ("L"). Studies with quantitative information
are further assessed to provide quantitative exposure concentrations; these studies all had high or
medium ratings. For products where quantitative information was not available in the literature,
exposure and risk potential is either discussed qualitatively or unable to perform a full quantitative
assessment ("None" in last column). Products that are not likely to result in fiber releases from routine
use or modifying activity was deemed qualitative analysis and no further analysis was performed
("None" in last column). For the scenarios evaluated quantitatively, the activity-based scenarios include
scenarios where the product/article is either disturbed or replaced (or both).
3.1.3.3 Concentrations of Asbestos in Activity-Based Scenarios
Studies identified in Table 3-5 were used to estimate exposure concentrations for each activity-based
scenario. The concentrations identified for bystanders were reported area air concentrations or
approximated concentrations using a reduction factor (RF). For activity-based scenarios that have
reported both personal data (which represents DIY users) and area data (which represents bystanders),
RFs were calculated by dividing the personal exposure concentration by the area exposure
concentration. The resulting RFs were averaged across all activity-based scenarios to obtain an overall
average default RF value of 6. This RF was used to approximate concentrations for activity-based
scenarios that did not have bystander (area) data reported. For these scenarios, the reported personal
exposure concentration for DIY users was divided by 6 to obtain the bystander exposure concentration.
The scenarios evaluated quantitatively extracted data are summarized in Table 3-6.
3.1.3.4 Summary of Inhalation Data Supporting the Consumer Exposure Assessment
Table 3-6 summarizes the activity-based asbestos concentration data from the above studies identified
by the systematic review process for each subcategory evaluated quantitatively for consumers and
bystanders. The low-end (LE), central (CT), and high-end (HE) tendency concentrations for each DIY
activity-based scenario for users and bystanders are summarized by specific product examples and by
COU. The references identified via the systematic review process are also described by year of sampling
or performed activity, method used to characterize asbestos fibers, and the systematic review rating
result for the specific reference. All but one reference had ratings of medium and the one reference was
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1639 rated as high, indicating that the studies had a few minor faults, but overall appropriate to use in this
1640 analysis. The year sampled also provides confidence in application of the data for current exposure
1641 scenarios considering legacy uses of asbestos containing products. These inhalation concentrations are
1642 used to calculate the risk estimates in Sections 5.1.3 and 5.3.2.3.
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Table 3-6. Summary of Activity-Based Scenario Studies and Exposure Point Concentrations
Product
Example
Activity-Based Scenario
Systematic Review Studies
Activity-Based Scenario Concentrations (f/cc)
Source
Year
Method
Rating
DIY User
Bystander
LE
HE
CT
LE
HE
CT
Construction, paint, electrical, and metal products COU: construction and building materials covering large surface areas subcategory
Roofing
materials
Outdoor, disturbance/repair
(sanding or scraping) of
roofing materials
(Mowat et al..
2007)
2005
PCME
High
0.0044
0.0097
0.0069
0.00074 °
0.0016°
0.0012°
Outdoor, removal of roofing
materials
(Lanse et al..
2008)
2000
PCM
Medium
0.005 b
0.01 b
0.005 b
0.005 b
0.01 b
0.005 b
Plaster
Indoor, removal of plaster
(Lanse et al..
2008)
2000
PCM
Medium
0.01
0.05
0.02
0.005 6
0.01 6
0.005 6
Ceiling tiles
Indoor, disturbance (sliding)
of ceiling tiles
(Boelter et al..
2016)
2016
PCME
Medium
0.023 b
0.045 b
0.023 b
0.023 b
0.045 b
0.023 b
Indoor, removal of ceiling
tiles
(Lanse et al..
1993)
1991
PCM,
TEM
Medium
0.005
0.019
0.009
0.0008 °
0.0032 °
0.0015 °
Flooring
tiles
Indoor, removal of vinyl floor
tiles
(Lundsren et al..
1991)
1990
PCM,
SEM
Medium
0.0056 c
0.0056 c
0.0056 c
0.0004 c
0.0004 c
0.0004 c
Loose-fill
Insulation
Indoor, disturbance/repair
(cutting) of attic insulation.
(Ewins et al..
2010)
2010
PCM
Medium
1.16 c
1.16 c
1.16 c
0.493 c
0.493 c
0.493 c
Indoor, moving and removal
(with vacuum) of attic
insulation
(Ewins et al..
2010)
2010
PCM
Medium
0.97
9.27
5.12
0.455
1.543
0.999
Construction, paint, electrical, and metal products COU: fillers and putties subcategory
Spackle
Indoor, disturbance (pole or
hand sanding and cleaning) of
spackle
(Rohl et al..
1975)
1979
PCM
Medium
1.25
25.87
13.9
1.95
9.55
5
Coatings,
mastics,
adhesives
Indoor, disturbance (sanding
and cleaning) of coatings,
mastics, and adhesives
(Paustenbach et
al.. 2004)
2004
PCME
Medium
0.023
0.04
0.023
0.003
0.008
0.003
Mastic
Indoor, removal of floor
tile/mastic
(Lanse et al..
2008)
2000
PCM
Medium
0.005 b
0.01 b
0.005 b
0.005 b
0.01 b
0.005 b
Caulking
Indoor, removal of window
caulking
(Lanse et al..
2008)
2000
PCM
Medium
0.005 6
0.01 6
0.005 6
0.005 6
0.01 6
0.005 6
Furnishing, cleaning, treatment care products COU: construction and building materials covering large surface areas, including fabrics, textiles, and apparel
subcategory
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Product
Example
Activity-Based Scenario
Systematic Review Studies
Activity-Based Scenario Concentrations (f/cc)
Source
Year
Method
Rating
DIY User
Bystander
LE
HE
CT
LE
HE
CT
Oven
mittens and
potholders
Use of mittens for glass
manufacturing, (proxy for
oven mittens and potholders)
(Cherrie et al..
2005)
2005
PCM
Medium
0.12
0.53
0.29
0.02°
0.088 a
0.049 a
" No area data was reported for bystanders; default average RF of 6 was used to estimate bystander exposure concentrations.
b Non-detect scenario; LOD was used for HE and Vi LOD was used for CT and LE.
c Study only reported one value; this was used for LE, HE and CT.
f/cc = fibers per cubic centimeter; LE = low-end; HE = high-end; CT = central tendency; PCM - phase contrast microscopy; PCME = PCE equivalent; RF = reduction
factor of 6; TEM = transmission electron microscopy
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3.1.3.5 Consumer DIY Scenarios Concentration Uncertainties and Variability
EPA targeted studies that aimed to replicate common activities with asbestos-containing materials and
followed acceptable sampling and analytical methods. This section explores the uncertainty associated
with the data used to build DIY activity-based scenarios for all product examples. Table 3-7 summarizes
the discussion points in this section.
As discussed in Section 3.1.3.1, there are numerous legacy asbestos-containing friable products that a
consumer might be able to encounter. However, the SR did not identify appropriate literature for every
potentially friable product expected to have some legacy use, and therefore, EPA could not quantify
activity-based scenarios for every friable product. In the absence of product or activity-based specific
data, EPA used proxies, approximations, and assumptions in some instances. In other instances, the
product was not evaluated, which remains an uncertainty despite the very low likelihood of a
consumer's exposure potential to these products.
For bystander exposures, only one paper Boelter et al. (2016) directly measured potential exposures to a
bystander (a person who was observing the ceiling panel work). For all other scenarios, area data were
used to approximate bystander exposure, and a default average RF of 6 was used to estimate bystander
exposure concentrations when studies did not report area data. Various factors may impact the
magnitude of exposures for bystanders. Particle deposition due to indoor air dynamics can reduce
particle transportation away from the activity. Additionally, distance from the activity can reduce
bystander exposures. As no adjustments were made to the RF to account for deposition or distance,
using the average value of 6 may potentially overestimate bystander exposures. Conversely, in the
studies reviewed, there was one instance in Rohl et al. (1975) where area measurements for sanding
spackling were greater than the personal measurements, suggesting it is possible for a bystander to have
greater exposures than a DIY user.
Due to the lack of specific information on DIY consumer exposures, occupational studies measuring
exposure to professionals were often used as proxies. There is uncertainty in using occupational data for
consumers due to differences in building volumes, air exchange rates, available engineering controls,
and potential use of PPE. If available, EPA used data under certain environmental conditions expected
to be more representative of a DIY user (i.e., no engineering controls and no PPE use). For example, in
Ewing et al. (2010). the authors studied attic insulation removal using both wet and dry methods, and
EPA only used the dry method data to evaluate DIY user exposures. It is assumed that DIY users still
use work practices that have been discontinued in professional settings or practices too sophisticated for
typical DIYers available resources.
There is uncertainty associated with studies that did not report asbestos size. Although EPA targeted
studies that reported asbestos concentrations for fibers >5 |im and 3:1 ratio (the "respirable" size range),
several of the identified studies did not report fiber size: Ewing et al. (2010). Lange et al. (1993).
Lundgren et al. (1991). Cherrie et al. (2005). Boelter et al. (2016). Mowat et al. (2007). Paustenbach et
al. (2004). and Lange et al. (2008). Generally, 50 to 98 percent of asbestos fibers are less than 5 |im,
according to Wilson et al. (2008) and Lee and Van Orden (2008). Including asbestos concentrations < 5
|im would result in the use of larger concentrations values, this means that the reported concentrations of
asbestos may overestimate risk.
Any air sampling measured only using PCM analysis may overestimate asbestos exposures as PCM
measures total fibers and does not determine the composition of fibers. The method on its own cannot
distinguish among different non-asbestos and asbestos fiber types. In the consumer evaluation, two
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papers only utilized PCM analyses, Lange et al. (2008) and Cherrie et al. (20051 so the selected
exposure point concentrations for the activity-based scenarios associated with these papers may result in
overestimates of asbestos exposure.
Table 3-7. Qualitative Assessment of the Uncertainty and Variability Associated with
Concentrations Data Used in Consumer Assessment
Variable Name
Effect
Uncertainty
(L, M, H) «
Variability
(L, M, H) «
Friable asbestos
classification h
Determination of products with potential to release
asbestos fibers.
M
L
Asbestos fiber sizes c
Concentration data used may include smaller particle
sizes and hence overestimate risk.
H
H
Overall sample analysis
method such as TEM,
PCM, SEM, PCME c
Non asbestos fibers specific methods may include
non-asbestos fiber concentrations and overestimate
risk. Most studies used TEM to confirm asbestos
fibers.
L
L
Overall consumer DIY
concentration data
Concentrations used in risk calculation estimates.
M
M d
"L = low; M = moderate; H = high
h Data sources for this information originated from this risk assessment assessor's professional judgment and NESHAP, 40
CFR Part 61, subpart M "friable asbestos" definition interpretation.
c Data sources for this information originated from the systematic review identified studies measurements.
J Low-end to high-end concentration ranges were within the same or one order of magnitude difference for all scenarios
concentrations.
3.1.4 Indoor Air
Asbestos-containing materials are still found in indoor environments such as residences, offices,
schools, and other public places that people frequent, primarily from the legacy use of in-service
building materials at the end of their life cycle. These exposures contribute to the totality of indoor air
exposure and correspond to the COU for (1) construction, paint, electrical, and metal products and (2)
furnishing, cleaning, treatment care products. Asbestos indoor air exposures can include indirect
exposures from minor uses and disturbances of legacy consumer products (e.g., attic insulation) in the
home (Section 3.1.2), job-related take-home exposures (Section 3.1.4), and infiltration of outdoor air in
urban/rural areas or areas of naturally occurring asbestos (Section 3.3.1). The relative contribution of
different sources of asbestos to the indoor environment is not well characterized. The indoor air
exposure assessment in this section focuses only on passive asbestos levels in buildings that have known
or unknown asbestos-containing materials in the building structure, not associated with the activity-
based consumer and take-home scenarios. EPA searched the systematic review extraction results for
representative data to use in a quantitative assessment, using the following criteria:
• Country: United States or Canada
• Timeframe: Sampling conducted since 2000
• Media Type: Indoor air or suspended dust
• Microenvironment: Living or common areas of residential buildings and public and
commercial buildings (including schools)
• Scenario/Source:
o Includes with or without the confirmed presence of ACM in the home or building, such
as attic insulation.
o Excludes monitoring of activity-specific consumer tasks and take-home exposure tasks
(see Section 3.1.2 and 3.1.4).
o Excludes monitoring following disasters (e.g., fallout from World Trade Center [WTC]
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terrorist attack) and monitoring influenced by legacy activities not under assessment in
Part 2, such as mining.
• Sampling Duration: Durations close to daily time spent indoors preferred (i.e., 8 hours).
No studies were identified which meet all of the above criteria for residential buildings, public buildings,
or school buildings. However, four US studies which met most of the criteria for residential buildings
are discussed in more detail below, including rationale for not continuing with quantitative analysis.
Tang et al. (2004) - Residential indoor concentrations of asbestos were measured in living rooms and
bedrooms of 25 apartment residences, as well as from 9 building-interior common areas in upper
Manhattan, New York, in 2002. While these indoor spaces were sampled following the World Trade
Center (WTC) terrorist attack in 2001, their location (5 to 12 miles from the WTC) was minimally
impacted by dust fallout, and the concentrations of various contaminants were intended to represent non-
apportioned levels due to building-related materials and combustion byproducts in urban residential
dwellings. The targeted asbestos fiber size for those quantified using PCM were greater or equal to 5 |im
and a ratio of greater or equal to 3:1, and sample duration was 8 hours. Quantification was also
conducted by TEM-AHERA (Asbestos Hazard Emergency Response Act; >0.5 |im and a ratio of >5:1)
and PCME (>5 |im and a ratio of >5:1). This study was not designed for specifically detecting asbestos
in indoor air and the presence of asbestos-containing material was not reported. PCM was used to
identify 21 samples out of 50 (42 percent) as containing fibers. Forty-eight samples were also analyzed
using TEM and PCME. For this further analysis, only two samples detected asbestos and both were at
the same level as the detection limit of 0.004 s/cc. In addition, neither method used the preferred fiber
size criteria (>5 jam) and a ratio of greater or equal to 3:1. Common areas of the apartment buildings
were also sampled with similar results. This study is not being used for a quantitative risk evaluation
because there were no detections above the detection limit and it does not satisfy the fiber size criteria.
Hoppe et al. (2012) - Asbestos fibers in indoor air were sampled from the family room of flood-
damaged residences after remediation (n = 47), following the cresting of the Cedar River in Cedar
Rapids, Iowa, in June 2008. Homes were originally built between 1890 and 2008. According to the
study, remediation followed "mucking and gutting" and generally entailed removal and replacement of
cabinetry, drywall, flooring, and insulation with a drying-out period between removal and replacement.
Asbestos samples were collected using active samplers for a 24-hour period and were analyzed using
PCM (fiber size and ratio not reported). Fibers were found via PCM in 27/47 samples, but this analytical
method only captures total fibers, and is not specific to asbestos. There was no confirmation of asbestos
in materials nor by confirmatory TEM sampling, likely because asbestos sampling was only one
contaminant on a more comprehensive list of indoor air contaminants, with the primary purpose of
identifying mold.
Lee and Van Orden (2008) - In the United States, indoor air samples were collected from 752 various
types of buildings, including 5 residential buildings and 234 public/commercial buildings, over a 10-
year period. The exact time period of sampling was not provided but was presumed to primarily occur in
the 1990s. The buildings sampled were the subject of litigation related to suits alleging the general
building occupants were exposed to a potential health hazard as a result of the presence of asbestos-
containing materials. Samples were collected under conditions of normal occupancy over a 2-day period
for at least an 8-hour sample duration. Sample analysis was conducted by TEM and results were
provided for various fiber definitions. However, this study did not report specific results and provided
no statistical information on the sampling such as minimum, maximum, or frequency of detection. Only
one average result was reported: 0.00005 f/mL via TEM. EPA did not use this concentration for a
quantitative risk evaluation because the data are not likely to represent current exposures and there is
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limited sampling data and methods reported—the one average residential sample reported was
calculated from other averages.
Spear et al. (2012) - Asbestos in indoor air of living spaces was measured in 46 homes in Montana with
the confirmed presence of asbestos in vermiculite attic insulation or other ACM. High-volume samples
were collected for a mean of 2 hours. All samples (n = 248) were analyzed by PCM, while only those
with a concentration exceeding 0.01 f/ mL by PCM or the two highest in each home (n = 158) were
further analyzed by TEM. Fiber size and ratio were not reported for either method. TEM results found
15 samples (9.5percent) detected asbestos and one exceeded 0.01 structures/cc, which is the Montana
clearance level. This sample was from a basement with asbestos containing structures, but the actual
concentration was not reported.
For U.S./Canadian studies with public building or school building data collected since 2000, the studies
were not appropriate for the assessment because they were activity based (during repair or removal of
ACM) and evaluated under the consumer DIY scenarios in Section 3.1.3. Therefore, extracted data for
these microenvironments are not further discussed.
The Asbestos-Containing Materials in Schools Rule pursuant to the Asbestos Hazard Emergency
Response Act (AHERA) was promulgated in 1987 with the purpose of inspecting schools for asbestos-
containing material, preparing asbestos management plans and conducting needed asbestos response
actions (i.e., asbestos removal, encapsulation, enclosure, or repair) to prevent or reduce asbestos hazards.
The focus of the AHERA program is to manage the identified asbestos-containing material in place and
undisturbed if non-friable (preferred approach) or perform asbestos response actions to address damaged
or friable asbestos. The associated AHERA data were not used in this indoor evaluation as most of it is
not representative of non-occupational exposures. The AHERA data relate to occupational exposures
during abatement efforts in which engineering and administrative controls along with PPE are required
and careful approaches are used to prevent exposure to the general population.
3.1.4.1 Conclusions for Indoor Air
The available information regarding passive or non-source attributed asbestos concentrations in indoor
air of residential and public buildings is not sufficient for EPA to conduct a quantitative exposure
assessment. This is not unexpected, as literature suggests that asbestos levels in indoor air are not
typically detected unless the asbestos-containing material is disturbed in some way that allows fibers to
become airborne; the mere presence of ACM in a building does not equate to asbestos exposure, as
shown in Tang et al. (2004). As such, most studies determine asbestos concentrations from activity-
based sampling conducted during disturbances of ACM. EPA has evaluated handler (user) and bystander
(non-user) activity-based scenarios in Section 3.1.1 for occupational exposures, Section 3.1.2 for
consumer exposures, and in Section 3.1.3 for take-home exposures.
3.2 Environmental Releases
3.2.1 Industrial and Commercial
EPA combined its estimates for annual releases, release days, and number of sites to estimate a range of
daily air, water, and land releases for each OES. A summary of releases across sites is presented in
Table 3-8. These release estimates are for total releases from a site and may include multiple points of
release, such as multiple outfalls for discharges to surface water or multiple points sources for air
emissions. Site-specific releases, estimation methodology, and details on deriving the overall confidence
score for each OES in Table 3-8 are presented in Appendix E. It is important to note that EPA provides
qualitative assessments of potential releases for the Handling of vermiculite-containing products OES
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1819 releases and number of sites are not quantified for the two aforementioned OESs.
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1821
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3.2.1.1 Summary of Daily Environmental Release Estimates
Table 3-8. Summary of Daily Environmental Release Estimates for Asbestos
Occupational Exposure
Scenario (OES)
Type of Discharge,
Air Emission," or
Transfer for
Disposal6
Number
of Sites
with
Releasesc
Estimated Daily Release Range
across Sites
(kg/site-day)
Estimated
Release
Frequency
across Sites
(days)"
Weight of
Scientific
Evidence
Conclusion
Sources
Min
Max
Handling asbestos-
containing building
materials during
maintenance, renovation,
and demolition activities
Fugitive air
46,789
7.6E-04
0.15
12
Moderate to
Robust
TRI, NEI
Stack air
46,789
0
0
TRI, NEI
Surface water
46,789
0.11
4.0
NRC
Landfill
46,789
411
814
TRI
Handling asbestos-
containing building
materials during
firefighting or other
disaster response
activities
Fugitive air
97,920
9.1E-03
1.8
1
Moderate
Surrogate
OES Data6
Stack air
97,920
0
0
Surface water
97,920
1.4
45
Landfill
97,920
4,935
9,764
Use, repair, or removal of
industrial and commercial
appliances or machinery
containing asbestos
Fugitive air
29,211
9.1E-05
9.0E-02
250
Moderate to
Robust
TRI, NEI
Stack air
29,211
0
6.6E-05
TRI, NEI
Surface water
29,211
0
0
TRI,
Professional
Judgment'
Landfill
29,211
67
627
TRI
Handling articles or
formulations that contain
asbestos
Fugitive air
15,592
2.7E-04
0.35
250
Moderate to
Robust
TRI, NEI
Stack air
15,592
8.5E-03
1.4E-02
TRI, NEI
Surface water
15,592
0
0
TRI,
Professional
Judgment'
Landfill, transfer to
waste broker
15,592
56
233
TRI
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Occupational Exposure
Scenario (OES)
Type of Discharge,
Air Emission," or
Transfer for
Disposal6
Number
of Sites
with
Releasesc
Estimated Daily Release Range
across Sites
(kg/site-day)
Estimated
Release
Frequency
across Sites
(days)"
Weight of
Scientific
Evidence
Conclusion
Sources
Min
Max
Waste handling, disposal,
and treatment
Fugitive air
4,972
6.3E-03
7.4E-02
250
Moderate to
Robust
TRI, NEI
Stack air
4,972
9.1E-04
9.5E-02
TRI, NEI
Surface water
4,972
0
0
TRI,
Professional
Judgment'
Landfill, off-site
management
4,972
765
1.0E04
TRI
"Emissions via fugitive air; stack air; or post-incineration emissions.
h Transfer to surface impoundment, land application, or landfills.
c Where available, EPA used U.S. Census Bureau data and literature search data to provide a basis to estimate the number of sites using asbestos within an
OES.
J Where available, EPA used literature search data and assumptions to provide a basis to estimate the number of release days of asbestos within an OES.
'' For this OES, EPA assumed that the releases from an uncontrolled fire/clean-up would be similar to releases from demolition. Therefore, this estimate uses
the calculated air releases from maintenance, renovation, and demolition activities.
' The TRI data gathered shows no discharges of asbestos to water. There may be incidental discharges of asbestos from this OES; however, EPA expects those
releases to be low.
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3.2.1.2 Weight of Scientific Evidence Conclusions for Environmental Releases from
Industrial and Commercial Sources
For each OES, EPA considered the assessment approach, the quality of the data and models, and
uncertainties in assessment results to determine a level of confidence as presented in Table 3-8.
The Agency considered factors that increase or decrease the strength of the evidence supporting the
release estimate—including quality of the data/information, applicability of the release data to the COU
(including considerations of temporal relevance, locational relevance) and the representativeness of the
estimate for the whole industry. The best professional judgment is summarized using the descriptors of
robust, moderate, slight, or indeterminant, according to EPA's Asbestos Part 2 Systematic Review
Protocol. For example, a conclusion of moderate is appropriate where there is measured release data
from a limited number of sources such that there is a limited number of data points that may not cover
most or all of the sites within the OES. A conclusion of slight is appropriate where there is limited
information that does not sufficiently cover all sites within the OES, and the assumptions and
uncertainties are not fully known or documented. See EPA's Draft Systematic Review Protocol
Supporting TSCA Risk Evaluations for Chemical Substances (U.S. EPA. 2018a) for additional
information on weight of scientific evidence conclusions.
For air, water, and land releases, all monitoring data had data quality ratings of medium/high. For
releases modeled with TRI/NEI/NRC, the weight of scientific evidence conclusion was moderate to
robust since information on the conditions of use of asbestos at sites in TRI and NEI is limited, and NRC
does not provide the condition of use of asbestos at sites. For the handling asbestos-containing building
materials during firefighting or other disaster response activities OES, the weight of scientific evidence
conclusion was moderate since surrogate data from a different OES were utilized. While the surrogate
monitoring data had data quality ratings of medium/high, use of surrogate data may introduce
uncertainties related to the extent to which the surrogate OES and the OES being assessed are similar.
See Appendix E for a summary of EPA's overall weight of scientific evidence conclusions for its release
estimates for each of the assessed OESs.
3.2.1.2.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for
the Environmental Release Assessment
EPA estimated air, water, and land releases of asbestos using various methods and information sources,
including TRI, NEI, and NRC data, surrogate OES data, and best professional judgement.
EPA estimated air and land releases using reported discharges from the 2016 to 2020 TRI. TRI datum
for asbestos were determined to have an overall data quality rating of medium through EPA's systematic
review process. However, TRI data are self-reported and have reporting requirements that exclude
certain sites from reporting. Due to these limitations, some sites that handle asbestos may not report to
these data sets, are not included in this analysis and therefore actual environmental exposures may be
underestimated. Sites are only required to report to TRI if the facility has 10 or more full-time
employees, is included in an applicable North American Industry Classification System (NAICS) code,
and manufactures, processes, or uses the chemical in quantities greater than a certain threshold (25,000
lb for manufacturers and processors and 10,000 lb for users). In addition, facilities are only required to
disclose asbestos waste management practices and releases for the portion of asbestos that is friable. TRI
reporting is not required for other forms of asbestos (e.g., non-friable asbestos, asbestos in aqueous
solutions), which is a limitation of this assessment. Information on the use of asbestos at sites in TRI is
limited; therefore, there is some uncertainty as to whether the number of sites estimated for a given OES
do in fact represent that specific OES. While annual releases for a given site or facility are the same
regardless of the OES under investigation, the daily discharge of the site or facility depends on the
number of release days per year for the OES.
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EPA estimated air releases using reported discharges from 2014 and 2017 NEI data. NEI was
determined to have an overall data quality rating of high through EPA's systematic review process. NEI
is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria precursors, and
hazardous air pollutants from air emissions sources. The NEI is released every 3 years based primarily
upon data provided by state, local, and tribal air agencies for sources in their jurisdictions and
supplemented by data developed by EPA. While state, local, and tribal air agencies are required to report
for criteria pollutants, reporting of hazardous air pollutants, such as asbestos, is voluntary. Therefore,
NEI may not include data from all emission sources. Like TRI, information on the use of asbestos at
sites in NEI is limited. Consequently, there is some uncertainty as to whether the number of facilities
estimated for a given OES do in fact represent that specific OES. While annual releases for a given site
or facility are the same regardless of the OES under investigation, the daily discharge of the site or
facility depends on the number of release days per year for the OES.
EPA estimated water releases using reported discharges from 2016 to 2022 NRC data. NRC was
determined to have an overall data quality rating of medium through EPA's systematic review process.
The NRC is a part of the federally established National Response System and staffed by the U.S. Coast
Guard. It is the designated federal point of contact for reporting all oil, chemical, radiological, biological
and etiological discharges into the environment. However, the NRC only fields the initial incident
reports that have not been validated or investigated by federal/state response agencies. Therefore, there
is some uncertainty in the accuracy of the information in the NRC data. For example, spill quantities are
often estimated or unknown. It is also possible that not all spill incidents are reported to the NRC such
that the available data likely does not encompass all spill related releases of asbestos.
Regarding estimation of the number of release sites, EPA relied on data from the U.S. Census for the
following three OESs: Use, repair, or removal of industrial and commercial appliances or machinery
containing asbestos; Handling articles or formulations that contain asbestos; and Waste handling,
disposal, and treatment. In such cases, the average daily release calculated from sites reporting to TRI,
NEI or NRC was applied to the total number of sites reported in (U.S. BLS. 2023). It is uncertain how
accurate this average release is to actual releases at these sites; therefore, releases may be higher or
lower than the calculated amount.
For the Handling asbestos-containing building materials during maintenance, renovation, and demolition
activities OES, EPA estimated number of sites through literature data. In the late 1980s, it was estimated
that 20 percent of buildings contain friable asbestos (U.S. EPA. 1988a). Similarly, for the Handling
Asbestos-Containing Building Materials During Firefighting or Other Disaster Response Activities
OES, one source estimated that 489,600 structure fires take place each year (NFPA. 2022a). This figure
in combination with the estimate of buildings with friable asbestos was used to estimate the number of
sites for this OES. Since the percentage of buildings with asbestos was estimated nearly 40 years ago
and asbestos use in construction has reduced since then, there is uncertainty resulting from this
conservative estimate. In addition, there is adding uncertainty in the assumption that all structure fires
are building fires. This could lead to an over or underestimation of the number of sites for these OESs.
In addition, the number of release days for these OES was estimated through literature data. For the
Handling asbestos-containing building materials during maintenance, renovation, and demolition
activities OES, four literature sources were compiled, averaging 12 release days/yr. For Handling
asbestos-containing building materials during firefighting or other disaster response activities, one
source was identified that stated 1 day/yr. There is uncertainty whether the compiled literature is
representative of all demolition and firefighting sites. This could lead to an over or underestimation of
the number of sites for these OESs.
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3.3 Concentrations of Asbestos in the Environment
The environmental exposure characterization focuses on air, land, and aquatic releases of asbestos from
activities that use or dispose asbestos under industrial and/or commercial conditions of use in this risk
evaluation. To characterize environmental exposure, EPA assessed point estimate exposures derived
from both measured and predicted concentrations of asbestos in ambient air, surface water, and
sediments in the United States.
3.3.1 Ambient Air Pathway
Sources of asbestos fibers in ambient air can be from construction materials that are damaged by
demolitions and remodeling projects, weathering, disposal of asbestos containing materials, activities
under all OESs and COUs, and disturbance of natural sources containing asbestos. The following
sections summarize the data used to evaluate environmental and general population exposures from
available studies that have measured asbestos in ambient air (Section 3.3.1.1) and modeling efforts for
environmental releases from activity-based scenarios (Section 3.3.1.2).
3.3.1.1 Measured Concentrations in Ambient Air
Table 3-9 Ambient air scenarios are matched to COUs that best fit under the description provided by the
study. One or several COUs can be matched to a scenario depending on the activities performed or
materials identified as sources of asbestos by the studies.
Table 3-9. Summary of Published Literature for Measured Ambient Air Concentrations
cou
Ambient Air
Scenario
Source Description
Summary Stats Per Proposed
Scenario (f/cc)
LEfl
CT6
HEC
Construction, paint,
electrical, and metal
products
Near source in
public urban space
during remodeling
and demolition
activities
(Lanae et al.. 2008)
Location: Eastern US
Sampling Date: 2000
Rating: Medium
3.1E-3
1.1E-2
2.0E-2
Furnishing,
cleaning, treatment
care products
(Neitzel et al.. 2020)
Location: Detroit, MI
Sampling Date: 2017
Rating: Medium
Construction, paint,
electrical, and metal
products
Near source urban
public space with
fireproofing material
(Nolan and Lanaer. 2001)
Location: Various U.S.
Sampling Date: 2001
Rating: Medium
1.0 E-3
1.7E-3
2.2E-3
Furnishing,
cleaning, treatment
care products
Disposal, including
distribution for
disposal
Perimeter to
asbestos disposal
and waste locations
(ATSDR. 2015)
Location: Ambler, Montgomery
County, Pennsylvania, BoRit Site
Sampling Date: 2008 and 2010
Rating Medium
3.0E-4
5.3 E-3
6.3 E-3
" LE is low-end tendency, usually the 10th percentile values if multiple data points are available or the minimum value of
one range reported.
b CT is the central tendency, 50th percentile if ranges are reported.
c HE is the high-end tendency, 95th percentile if multiple data points are available or the maximum value of one range
reported.
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EPA identified studies that reported measured asbestos concentrations in ambient air via the systematic
review process summarized in Table 3-9. A detailed description of reported data sources and statistics is
available in Appendix F. 1. The studies are from the year 2000 and after to evaluate asbestos exposure
concentrations using data that best represents current asbestos fiber releases in the United States.
• Lange et al. (2008) - The goal of this study is to determine exposure to airborne asbestos during
abatement of ceiling material, window caulking, floor tile and roofing materials. Perimeter and
other types of samples were collected within 10 ft of the containment structure that was under
abatement. The building was a school in the eastern part of United States with asbestos
containing materials. The type of samples used in this ambient air analysis was the perimeter
samples. The samples were a composite of at least 2 hours and were analyzed with PCM. The
study reported minimum, maximum, arithmetic mean, and geometric mean values of the five
types of products getting removed. All were under the detection limit. The study description was
linked to emissions of asbestos near the source during remodeling/demolition activities.
• Neitzel et al. (2020) - The objective of this study is to report asbestos measurements taken
during the demolition of abandoned residential dwellings in urban locations. Investigators
collected air samples about 60 ft from around the demolition of 25 abandoned residential
dwellings and used TEM and PCM to analyze the samples. The study reported the number of
samples above the limit of detection, and the median, 75th percentile and 90th percentile
concentrations. Only the 90th percentile reported a value for 2 samples (out of 46) that contained
asbestos fibers. The study description was linked to emissions of asbestos near the source during
remodeling/demolition activities.
• Nolan and Langer (2001) - Asbestos fibers were measured inside and outside buildings
containing asbestos from fireproofing materials. The goal of this study was to characterize the
airborne concentrations of asbestos fiber at twelve sites in and around buildings in diverse
geographical locations in the United States. The sampling strategy involved collecting both area
samples (where the sampling pump remained in one location during the entire period of
sampling) and personal samples (where the pump was attached to an individual). The various
locations are public spaces, such as airport terminals, convention centers, and schools. Samples
were analyzed with ATEM (analytical transmission electron microscope). The study reported the
average of nine samples that were below the detection limit. Only area samples were used for
this analysis and were linked to emissions of asbestos near sources such as asbestos containing
construction and fireproofing material.
• ATSDR (2015) - The goal of this study was to evaluate exposure of a community to potentially
harmful contaminants and make any necessary recommendations to prevent and mitigate
exposures, as well as to ensure that the community has the best information possible to protect
their health. Sampling was conducted at the BoRit Asbestos Site, historically used to dispose of
asbestos-containing materials from the Keasbey & Mattison Company (K&M). The site is no
longer active, yet waste material remains in place. Each sampling event was 24 hours in duration,
and samples were analyzed via TEM. Fiber sizes corresponding to PCM, AHERA, and Berman-
Crump (TEM particle size and type) protocol fibers were documented. The study reported for
years 2008 and 2010, a minimum from one sample that was below detection limit, and a
maximum from the average of two samples that were above the detection limit. The data used for
this section of the RE were collected outside the perimeter of the BoRit site and are considered
non-source attributed asbestos disposal and waste handling activities.
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3.3.1.2 Modeled Concentrations in Ambient Air
Releases of asbestos fibers to ambient air from various industrial/commercial activities, described by
occupational exposure scenarios (OES), were used to estimate environmental concentrations and general
population exposure to these releases in Section 3.1.1.1. Table 3-1 and Table 3-10 summarize the OES
mapping to COUs and product examples. EPA used the Integrated Indoor-Outdoor Air Calculator
(IIOAC), and the American Meteorological Society (AMS)/EPA Regulatory Model (AERMOD) to
estimate ambient air concentrations and particle deposition of asbestos from facility releases and
activity-based releases. IIOAC uses pre-run results from a suite of AERMOD dispersion scenarios at a
variety of meteorological and land-use settings, as well as release emissions, to estimate particle
deposition at different distances from sources that release chemical substances to the air. AERMOD, a
higher tier model, was utilized to incorporate refined parameters for asbestos particles suspended in air
as well as asbestos particle deposition.
The full inputs and results of IIOAC and AERMOD are described and presented in Appendix F and
Asbestos Part 2 Draft RE - AERMOD Inputs and Outputs - Fall 2023 Supplemental File (see also
Appendix C). Briefly, AERMOD is a steady-state Gaussian plume dispersion model that incorporates air
dispersion based on planetary boundary layer turbulence structure and scaling concepts, including
treatment of both surface and elevated sources and both simple and complex terrain. AERMOD can
incorporate a variety of emission source characteristics, chemical deposition properties, complex terrain,
and site-specific hourly meteorology to estimate air concentrations and deposition amounts at user-
specified distances points of exposure and at a variety of averaging times. Readers can learn more about
AERMOD, equations within the model, detailed input and output parameters, and supporting
documentation by reviewing the AERMOD users guide (U.S. EPA. 2018c).
A full description of the input parameters selected for AERMOD and details regarding post-processing
of the results are provided in the Appendix F.2. EPA reviewed available literature to select input
parameters for deposition, particle sizes, meteorological data, urban/rural designations, and physical
source specifications (stack and fugitive releases). The ambient air environmental releases scenarios by
OES are for annual emissions for specific and generic facilities, fugitive and stack releases, rural and
urban populations (generic facilities only), and high-end and central tendency releases and
meteorological conditions (generic facilities only).
• The term facilities in this RE applies to permanent locations as well as temporary because
activities that release asbestos can be transitory, such as demolition, removal, and repair of
asbestos containing structures and materials, use and repair of appliances and machinery, and
firefighting activities. EPA developed scenarios for TRI facilities with ranges of emission rates
for unknown and transitory activities and are referred to as "generic facilities." Specific facilities
are those that reported TRI and NEI emission data and description of asbestos release activities
which are matched to an OES. In addition, Table 3-10 summarizes OES for which EPA
estimated released concentrations for specific and generic facilities.
• Fugitive and stack releases are two source types. Stack releases are a point source, and fugitive
releases are area source releases. These source types have different plume and dispersion
characteristics that are accounted for differently within the model. Because AERMOD stack
modeling is for real stack emissions and requires inputs for stack operation, see Section F.2.3,
EPA deemed this modeling effort to not be representative of asbestos point source emissions for
activities performed at the temporary or stationary locations in which asbestos fibers are
released.
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• All generic facilities were simulated as rural and urban. A facility is in an urban area if it had a
population density greater than 750 people per square kilometer (km) within a 3-km radius.
• All modeling scenarios utilized several rings of estimating exposures at distances 10, 30, and
60m from the source for co4ocated general populations and 100 to 1,000, 2,500, 5,000, and
10,000m from the source for non-co4ocated general population.
• Specific facilities meteorological data used the same AERMOD-ready meteorological data that
EPA's Risk and Technology Review (RTR) program uses for risk modeling in review of
National Emission Standards for Hazardous Air Pollutants (NESHAP). The RTR 2019
meteorological data set was used to model emission years 2018 and 2019. Meteorological data
from 2016 were used for emission years 2014 to 2017, covering 824 stations, which the RTR
program used prior to the updates to the 2019 data set. Generic facilities meteorological data
were modeled twice with two different meteorological stations. EPA's IIOAC utilized a
meteorological station for each region of the country, and from this data set, it was determined
that meteorological conditions from Sioux Falls, South Dakota, led to central tendency (CT)
modeled concentrations and particle deposition. Meteorological conditions from Lake Charles,
LA led to high-end (HE) modeled concentrations relative to the other regional stations.
• Central tendency and high-end annual air concentrations were calculated for generic facilities
releases using the central tendency and high-end release rate data, which corresponds to the
average and the 95th percentiles.
Table 3-10. Release Scenarios Considered for Ambient Air and Deposition Modeling
OES
COU and Subcategory
Facility
Specific
Fugitive
Analysis
Generic
Facility
Fugitive
Analysis
Handling articles or
formulations that
contain asbestos
COU: Construction. Paint. Electrical, and Metal Products
Subcategory: Solvent-based/water-based oaint. fillers, and
putties
COU: Furnishing. Cleaning. Treatment Care Products
Subcategory: Furniture & furnishings including stone, plaster,
cement, glass, and ceramic articles; metal articles; or rubber
articles
COU: Packaging. Paocr. Plastic. Tovs. Hobbv Products
Subcategory: Packaging (excluding food packaging), including
rubber articles; plastic articles (hard); plastic articles (soft) and
Toys intended for children's use (and child dedicated articles),
including fabrics, textiles, and apparel; or plastic articles (hard)
Handling asbestos-
containing building
materials during
maintenance,
renovation, and
demolition
activities
COU: Construction. Paint. Electrical, and Metal Products
Subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone,
plaster, cement, glass, and ceramic articles
COU: Furnishing. Cleaning. Treatment Care Products
Subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
Use, repair, or
disposal of
industrial and
commercial
appliances or
COU: Construction. Paint. Electrical, and Metal Products
Subcategory: Machinery, mechanical appliances,
electrical/electronic articles and other machinery, mechanical
appliances, electronic/electronic articles
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OES
COU and Subcategory
Facility
Specific
Fugitive
Analysis
Generic
Facility
Fugitive
Analysis
machinery
containing asbestos
Waste handling,
disposal, and
treatment fugitive
annual ambient air
risk
COU and subcategory: Disposal, including Distribution for
Disposal
S
Handling asbestos-
containing building
materials during
firefighting or other
disaster response
activities
COU: Construction. Paint. Electrical, and Metal Products
Subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone,
plaster, cement, glass, and ceramic articles
COU: Furnishing. Cleaning. Treatment Care Products
Subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
S
Specific Facilities
The modeled asbestos air concentrations for annual releases for specific facilities by OES tables are
available in Asbestos Part 2 Draft RE - Ambient Air Specific Facilities Released Concentrations - Fall
2023 Supplemental File (see Appendix C) and a description of the outputs is available in Appendix F.
Figure 3-5 shows overall annual air asbestos fiber concentration patterns for specific facilities by OES.
The range bars show the low and high-end tendencies, which were calculated from the average of the
10th and 95th percentiles for each OES.
• Figure 3-5 shows an overall pattern of decreasing ambient air asbestos fiber concentrations (f/cc)
away from the source for all OES for all fugitive emissions from specific facility.
• The decreasing pattern also shows that each OES concentration decreases about one order of
magnitude from one distance marker to the next. The asbestos concentrations in air have a sharp
drop for fugitive emissions between the co-located distances and general population, after the
100 m mark (not visible in the figures due to the log scale).
• The figures also show a wide range of asbestos concentrations among OES at the same distance
from the source ranging from 1 to 3 orders of magnitude difference.
• The cascading decreasing pattern for each distance shows the order of larger to smaller
concentrations by OES:
o Area emissions from activities related to handling asbestos-containing building materials
during maintenance, renovation, and demolition
o Area emissions from activities related to use, repair, or disposal of industrial and
commercial appliances or machinery containing asbestos
o Area emissions from waste handling, disposal, and treatment
o Area emissions from activities handling articles or formulations that contain asbestos
Page 81 of 405
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2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
1.0E+00
1.0E-01
8 1.0E-02
J 1.0E-03
§
S 1.0E-04
o
a
3 1.0E-05
11.0E-06
11.0E-07
1.0E-08
1.0E-09
Distance from Source (m)
¦ Handling Asbestos-Containing Building Materials During Maintenance, Renovation, and Demolition Activities Fugitive
¦ Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery Containing Asbestos Fugitive
¦ Waste Handling, Disposal, and Treatment Fugitive
Handling Articles or Formulations that Contain Asbestos Fugitive
Figure 3-5. Specific Facilities Ambient Air Concentrations by Distance from Source for Each OES
Figure 3-5 depicts the summary of the specific facilities ambient air concentrations by OES, and each
OES bar in Figure 3-5 is composed of releases from multiple specific facilities with a wide range of
descriptions available in Appendix F (Figure Apx F-4, FigureApx F-5, FigureApx F-6, and
FigureApx F-7). The overall pattern of each figure in Appendix F is the same as that from Figure 3-5,
and the difference in concentrations among facilities under the same OES at the same distance from the
source can range from 3 to 6 orders of magnitude.
Generic Facilities
The modeled asbestos air concentrations for annual releases for generic facilities by OES tables are
available in Asbestos Part 2 Draft RE - Ambient Air Generic Facilities and Depo Concentrations - Fall
2023 Supplemental File (see Appendix C) and in Appendix F. Figure 3-6 shows simulated overall
annual air asbestos fiber concentration patterns for generic facilities by OES for fugitive emissions.
• Like specific facilities, the simulated generic facilities show a pattern of decreasing ambient air
asbestos fiber concentrations (f/cc) away from the source for all OES.
• Like specific facilities, the generic facilities also show a difference of 1 to 2 orders of magnitude
from distance marker to the next for the same generic facility simulation.
• There is no marked difference between rural and urban populations for concentrations within the
same distance marker.
• Fugitive emission concentrations for all OES at the same distance marker are all within the same
order of magnitude.
• There is a 2 orders of magnitude difference between HE and CT emissions (HE is shown by the
lined bars in the figures). The main difference driver is the use of meteorological data from Lake
Charles, Louisiana, for the HE emissions estimates and Sioux Falls, South Dakota, for CT
emissions estimates simulations.
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Co-located General Population
General Population
iili iih ini ini
1000 2500 5000 10000
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2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
1.00E+00
1.00E-01
£ 1.00E-02
to
"3" 1.00E-03
o
| 1.00E-04
s 1.00E-05
(3 1.00E-06
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2133
2134 Modeled generic and specific asbestos air concentrations from occupational activity-based scenarios are
2135 grouped and averaged by OES and divided by low-end, central, and high-end tendencies in Table 3-11
2136 and Figure 3-7, for a detailed grouping by ambient air analysis summary see Appendix F.3. The
2137 concentration values in Figure 3-5 and Figure 3-6 will be used to estimate risk to asbestos fiber
2138 inhalation by the general population, Section 5.1.4 and environmental exposures in Section 4.
2139
1.0E+00
1.0E-01
1.0E-02
_ 1.0E-03
o
& 1.0E-04
§ 1.0E-05
§ 1.0E-06
g 1.0E-07
m 1.0E-08
<
S 1.0E-09
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2142 Table 3-11. Ambient Air Concentration Summary"
OES
cou
Distance From the Source (m)
10
30
60
100
1,000
2,500
5,000
10,000
Low-end tendency ambient air concentrations
Waste handling, disposal,
and treatment fugitive
COU: Disposal, including
distribution for disposal
1.9E-3
2.5E-4
5.1E-5
1.4E-5
1.6E-7
2.2E-8
7.8E-9
2.7E-9
Handling asbestos-containing
building materials during
maintenance, renovation, and
demolition activities fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
4.5E-3
64E-4
1.2E-4
3.0E-5
2.5E-07
2.3E-8
9.3E-9
3.5E-9
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive
COU: Construction, paint,
electrical, and metal products
2.6E-3
3.0E-4
5.6E-5
1.6E-5
2.0E-07
2.9E-8
1.0E-8
34E-9
Handling articles or
formulations that contain
asbestos fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
COU: Packaging, paper, plastic,
toys, hobby products
3.1E-4
2.1E-4
2.0E-4
1.9E-4
44E-07
1.3E-7
5.0E-8
1.6E-8
Central tendency ambient air concentrations
Waste handling, disposal,
and treatment fugitive
COU: Disposal, including
distribution for disposal
4.5E-3
7.7E-4
1.8E-4
5.3E-5
1.8E-6
7.4E-8
2.6E-8
9. IE—9
Handling asbestos-containing
building materials during
maintenance, renovation, and
demolition activities fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
3.3E-3
6.3E-4
1.5E-4
4.4E-5
1.3E-6
5.1E-8
1.8E-8
7.0E-9
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive
COU: Construction, paint,
electrical, and metal products
2.1E-3
3.3E-4
7.5E-5
2.2E-5
7.9E-7
3.5E-8
1.3E-8
44E-9
Handling articles or
formulations that contain
asbestos fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
COU: Packaging, paper, plastic,
toys, hobby products
4.6E-4
24E-4
2.0E-4
1.9E-4
5.0E-6
2.8E-7
1.1E—7
4.0E-8
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OES
cou
Distance From the Source (m)
10
30
60
100
1,000
2,500
5,000
10,000
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
4.2E-6
1.1E-6
3. IE—7
1.0E-7
3.3E-9
1.0E-10
3.1E-11
1.1E—11
High-end tendency ambient air concentrations
Waste handling, disposal,
and treatment fugitive
COU: Disposal, including
distribution for disposal
8.7E-3
1.8E-3
4.5E-4
1.4E-4
6.0E-6
1.6E-7
5.5E-8
2.0E-8
Handling asbestos-containing
building materials during
maintenance, renovation, and
demolition activities fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
6.3E-3
1.3E-3
3.3E-4
9.9E-5
5.8E-6
1.2E-7
4.0E-8
1.5E-8
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive
COU: Construction, paint,
electrical, and metal products
1.4E-2
2.7E-3
6.9E-4
2.1E-4
7.7E-6
2.6E-7
9.0E-8
3.3E-8
Handling articles or
formulations that contain
asbestos fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
COU: Packaging, paper, plastic,
toys, hobby products
8.3E-4
3.2E-4
2.3E-4
2.1E-4
1.2E-5
4.5E-7
1.9E-7
6.9E-8
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive
COU: Construction, paint,
electrical, and metal products
COU: Furnishing, cleaning,
treatment care products
8.4E-4
2.1E-4
6.1E-5
2.0E-5
6.6E-7
2.1E-8
6.2E-9
2.3E-9
" Modeled generic and specific asbestos air concentrations from activity-based scenarios are grouped and averaged by OES and mapped to COUs in this table. A
detailed summary of the specific and generic facility results are in Appendix F.3.
Low-end tendency concentrations were calculated from the average of all 10th percentile modeled concentrations for specific and generic facilities.
Central tendency concentrations were calculated from the average of all 50th percentile modeled concentrations for specific and generic facilities.
High-end tendency concentrations were calculated from the average of all 95th percentile modeled concentrations for specific and generic facilities.
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3.3.1.4 Ambient Air Concentration Data Uncertainty and Variability
Sources of uncertainty in measured asbestos ambient air concentration data are related to the sample
collection and analysis in the studies EPA considered. These studies reported using TEM, PCM, and
other asbestos concentration analysis method. A detailed description of reported data sources and
statistics is available in Appendix F.l. TEM can distinguish between asbestos and non-asbestos fibers in
addition to asbestos fiber type identification capabilities. The use of TEM decreases uncertainties in the
identification of asbestos fibers and quantification. Of the studies considered, 2 out of 6 used PCM or
PCME to quantify asbestos concentrations and hence it is expected that these studies have greater
uncertainties. In addition, one study did not report particle size and one reported providing
concentrations for particles <5|im. Inclusion of particles less than 5|im will increase uncertainty and
variability as concentrations and concentration ranges will likely be larger.
Sources of uncertainty in modeled asbestos ambient air concentration data are related to the
environmental releases estimates discussed in Section 3.2.1.2, and modeling approaches approximations,
assumptions, and parameters. A detailed description of modeling inputs, assumptions, and
approximations are described in Appendix F.2.
Table 3-12. Qualitative Assessment of the Uncertainty and Variability Associated with
Concentration Data Used for Ambient Air
Variable Name
Effect
Data Source(s)
Uncertainty
(L, M, H)fl
Variability
(L, M, H)fl
Measured ambient air
concentration sample
analysis methods
Majority (2 of 6) of studies
used TEM that decreases
uncertainty
Systematic Review identified
studies measurements
6.4.IF.1
M
L
Asbestos fiber sizes
in measured ambient
air concentrations
Concentration data used may
include smaller particle sizes
and hence overestimate risk
Systematic Review identified
studies measurements,
Appendix F. 1
H
H
Overall measured
ambient air
concentration
Overall uncertainty in
concentration data used
Systematic Review
identified studies
H
H
AERMOD defaults
for air modeling:
meteorological data
specific facilities
Meteorological data
determines fate and transport
patterns away from source;
used locally reported data for
specific locations for current
conditions.
AERMOD model, Section
3.3.1.2, Appendix F.2
L
H
AERMOD defaults
for air modeling:
meteorological data
generic facilities
Meteorological data
determines fate and transport
patterns away from source;
generic facility estimates
used two data sets to
generalize and central and
high-end tendency
AERMOD model, Section
3.3.1.2, Appendix F.2
M
H
AERMOD defaults
for air modeling:
source specification
parameters for
fugitive emission
parameters
Height of emission for point
and area source emissions
can determine air mass
mixing and transport
tendencies.
AERMOD model, Section
3.3.1.2, Appendix F.2
M
H
AERMOD defaults
for air modeling:
Number of emissions per
year
AERMOD model, Section
3.3.1.2, Appendix F.2
M
H
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Temporal emission
parameters
Overall modeled
ambient air
concentration
Overall uncertainty in
concentration data used
AERMOD model
M
H
11L = low; M = moderate; H = high
Low-end to high-end concentration ranges were within the same to 1 order of magnitude difference for all scenarios
concentrations.
3.3.2 Water Pathway
3.3.2.1 Measured Concentrations in Surface and Drinking Water
Measured surface water concentrations were obtained from EPA's Water Quality Exchange (WQX)
using the Water Quality Portal (WQP) tool, which is the nation's largest source of water quality
monitoring data and includes results from EPA's STORage and RETrieval (STORET) Data Warehouse,
the U.S. Geological Service (USGS) National Water Information System (NWIS), and other federal,
state, and tribal sources, summarize in Table 3-13 with the label STORET (U.S. EPA et al.. 2023) in the
scenario description.
Through systematic review, other sources of asbestos concentrations in water were also identified. The
data selected for surface and drinking water in this section is summarized in Table 3-13 and Appendix
F.4 has details of selected and unused data. The published literature yielded information of surface water
monitoring data for asbestos. EPA identified surface water monitoring studies from various countries
ranging from 1971 to 2016. The data can be classified in three groups: surface water, well water, and
drinking water. EPA opted to only use surface and drinking water in this discussion as other water types
(groundwater, wastewater, and sediments) did not meet the integration criteria (see Appendix F.4). EPA
used data from 2008 forward and only U.S.-based studies to obtain a current representation of asbestos
concentrations in water from legacy uses, associated disposal, and possibly from natural sources.
• ATSDR (2015) - Measured asbestos in surface water on-site and off-site at BoRit. The site was
historically used to dispose of asbestos-containing materials, starting in the 1800s and ending in
1970. Remediation efforts are currently ongoing.
• ATSDR (2012) - Measured asbestos in groundwater on-site and off-site at BoRit.
• CDM Federal Programs Corporation (2014) - Libby asbestos superfund site ecological risk
assessment. Measured asbestos in various environmental media including freshwater from
various locations around the site.
• U.S. EPA (2016a) - The Six-Year Review 3 of drinking water database is the latest publicly
available set. This review is part of EPA's obligation to review each national primary drinking
water regulation. EPA evaluates any newly available data, information, and technologies to
determine if any regulatory revisions are needed. This database contains asbestos measurements
from 2006 to 2011 from all U.S. states, territories, including tribal lands. The database contains
approximately 12,084 data points of asbestos concentrations measured in drinking water
facilities, of the 12,084 data points, 330 measured asbestos above detection limit, and 15 samples
were above EPA's Maximum Contaminant Level (MCL).
The National Primary Drinking Water Regulations (NPDWR) establishes the MCLs3 for asbestos among
many other chemicals. These standards, base on potential health effects from long-term exposure apply
to public water systems and limit the levels of certain contaminants in drinking water. Asbestos MCL is
7><106 f/L (7><103 f/cc) with a potential risk of developing benign polyps from decay of asbestos cement
3 https://www.epa.gov/ground-water-and-drinking-water/national-primarv-drinking-water-regulations.
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in water mains and erosion of natural deposits. Table 3-13 summarized the comparison of water
concentrations to the MCL. Starting with the surface water rows from Libby, Montana, and the BoRit
site in Pennsylvania, is notable that samples close to the asbestos source will have larger concentrations
and exceed the MCL. In addition, efforts to clean and remediate Libby and BoRit sites started in 2012
and finished 2022, and the expectation was to observe less asbestos fibers as these efforts successfully
remove asbestos fibers. The reported BoRit and Libby sites 2009 and 2014 samples with asbestos
concentrations above the MCL are from pre-remediation efforts from surface water that are not used as a
source of drinking water directly, however it may be that some of the creeks, streams, rivers, and lakes
surface water from the Libby, Montana, site and the BoRit site will end up in bodies of water that source
drinking water. The BoRit site remediation efforts are reported for the years 2018, 2020, and 2021, for
two surface water sources within the site and show asbestos concentrations two orders of magnitude
below the pre-remediation efforts.
Table 3-13. Summary of Measured Surface and Groundwater Concentrations"
Source
Data
Quality
Date
Sampled
Sample Description
Concentration
(f/cc)
Comparison to MCL
(Drinking Water)
7E3 f/cc
CT
HE
CT
HE
(CDM Federal
Proerams
Coroo ration.
2014)
Medium
2014
Surface freshwater from creek stream
(Rainy, Carney, and Fleetwood Creeks)
close to source, Libby mine
7.3E3
5.2E5
Above
Above
(CDM Federal
Proerams
Coroo ration.
2014)
Medium
2014
Surface freshwater from Kootenai River
close to source, Libby mine
1.0E2
1.3E3
Under
Under
(CDM Federal
Proerams
Corooration.
2014)
Medium
2014
Surface freshwater from tailing, mill and
reference ponds close to source, Libby
mine
1.5E4
1.0E6
Above
Above
(U.S. EPA.
2022c)
2009
Surface water from on-site reservoir
close to source, BoRit asbestos disposal
site
1.7E8
5.4E8
Above
Above
(U.S. EPA.
2022c)
2018
Surface water from on-site reservoir
close to source, BoRit asbestos disposal
site
4.9E6
1.4E7
Above
Above
(U.S. EPA
2022c)
2020
Surface water from on-site reservoir
close to source, BoRit asbestos disposal
site
2.4E6
3.3E6
Above
Above
(U.S. EPA
2022c)
2021
Surface water from on-site reservoir
close to source, BoRit asbestos disposal
site
7.5E6
1.0E7
Above
Above
(U.S. EPA
2022c)
2009
Surface freshwater from creek stream
(Wissahickon Creek, Rose Valley Creek,
Tannery Run) close to source, BoRit
asbestos disposal site
1.4E7
2.9E7
Above
Above
(U.S. EPA
2022c)
2018
Surface freshwater from creek stream
(Wissahickon Creek, Rose Valley Creek,
Tannery Run) close to source, BoRit
asbestos disposal site
1.5E5
3.0E5
Above
Above
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Source
Data
Quality
Date
Sampled
Sample Description
Concentration
(f/cc)
Comparison to MCL
(Drinking Water)
7E3 f/cc
CT
HE
CT
HE
(U.S. EPA.
2022c)
2020
Surface freshwater from creek stream
(Wissahickon Creek, Rose Valley Creek,
Tannery Run) close to source, BoRit
asbestos disposal site
9.8E4
3.9E5
Above
Above
(U.S. EPA.
2022c)
2021
Surface freshwater from creek stream
(Wissahickon Creek, Rose Valley Creek,
Tannery Run) close to source, BoRit
asbestos disposal site
5.4E5
1.5E6
Above
Above
(ATSDR.
2012)
Medium
2011
Treated drinking groundwater from
BoRit asbestos disposal site county
8.20E1
NR
Under
N/A
(ATSDR.
2012)
Medium
2009-
2010
Drinking groundwater from monitoring
well at BoRit asbestos disposal site
2.0E2
5.1E2
Under
Under
(U.S. EPA et
al.. 2023)
High
2011-
2013
STORET City of Honolulu, Honouliuli
WWTP Plant
0
0
Under
Under
(U.S. EPA et
al.. 2023)
High
2012
STORET Random Private Potable
Ground Water Florida
7.90E-4
3.70E-4
Under
Under
(U.S. EPA et
al.. 2023)
High
2019-
2022
STORET Yavapai Prescott Indian Tribe,
Arizona (Tribal)
8.65E2
4.40E2
Under
Under
(U.S. EPA.
2016a)
Medium
2006-
2011
Drinking water throughout United States
0
0
N/A
N/A
" The majority of the data was non-detect, zeros, and the values in the table were calculated with all zeros to represent and
generalize to all of the United States. Without zeros the values would be 1.06E5 f/cc.
MCL = maximum contaminant level
If asbestos contaminated waters from mines, asbestos waste handling sites, or other sources end up in
drinking water, it is likely that the fibers are either diluted or removed by deposition or other processes
in the transport and mixing of cleaning drinking water sources process. This pattern is evidenced from
drinking water samples around the BoRit site that are under the MCL and drinking water from the 6-
year drinking water database, U.S. EPA (2016a). which show all sites to be under the MCL or show no
asbestos detected.
3.3.3 Land Pathway
Asbestos fibers in soils can lead to inhalation exposures as the settled particles are stirred up and
suspended to become available for inhalation. Asbestos in soils can either be naturally occuring or
released from asbestos containing products during construction/demolition, firefighting activities, and
waste and disposal of asbestos containing materials.
Emission of asbestos fibers in soil depend on disturbances. Soil disturbances resulting in soil erosion
depend on the size, weight, and wetness of the soil particles. Each individual soil particle needs to be
less than 1 mm (1,000 |im) to be moved by wind. Furthermore, suspension of soil particles tends to
happen for fine particles less than 0.1 mm (100 |im), and these can go long-range transport and reach
higher levels of the atmosphere beyond the troposphere. Saltation processes in which particles bounce
along the surface tend to happen for particles ranging from 0.05 to 0.5 mm (50 to 500 |im) and remain
within 30 cm of the surface. Soil creep is like saltation for larger particles, 0.5 to 2 mm (500 to 2,000
|im) in diameter (Queensland DERM. 2011). Bouncing particles, subject to saltation and soil creep, can
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further breakdown into smaller sizes and can undergo suspension. The particle sizes for suspension are
well within the range of the asbestos particle size targeted within this assessment (>5 |im, with a 3:1
ratio) and hence soils can be a source of asbestos for inhalation exposures.
A literature search was conducted to identify peer-reviewed references of measured asbestos
concentrations in United States soils. The search was narrowed to target studies that had sampled US
soils after the year 2000 and without mining influences to obtain representative concentrations for
current conditions. EPA only identified studies that reported on mining related activities or in areas that
are likely to be affected by their proximity to mines like Libby, Montana. Table 3-14 summarizes the
identified references, descriptions, and rationale for not utilizing these studies in the inhalation exposure
assessment. A detailed description of the studies is available in Appendix F.5.
Table 3-14. Soil Concentration Data Sources Description
Source, SR Rating"
Description
Rationale for Not Using
(CDM Federal
Proarams Corporation.
2015), High
Soil samples from town of Troy, Montana, from various
outside residential buildings such as driveways, yards,
gardens. Sampling was conducted the summer of 2011
and 2012 and reported Libby Amphibole concentrations.
Mining activity related
(Jones et al.. 2010).
Medium
Soil sample from town of Libby, Montana, reporting
Libby vermiculite relationship to mine activity. Study is
from 2010.
Mining activity related
11 SR rating is the overall systematic review rating for the study.
EPA modeled releases to ambient air from activities that are likely to result in subsequent deposition to
soil, refer to Section 3.3.4 for a discussion of asbestos concentrations onto soils from suspended asbestos
fibers. Specific and generic facilities ambient air modeling outputs and simulations results from Section
3.3.1.2 can be used to estimate release concentrations after deposition and re-suspension of asbestos in
soil particles from activities that can be traced to demolition/renovation, firefighting, and asbestos waste
handling activities, and use, repair, removal of asbestos containing machinery.
3.3.4 Modeled Deposition Rates from Environmental Releases
EPA used AERMOD to estimate air deposition from facility releases to calculate deposition
concentrations near specific and generic facilities. Asbestos particles may deposit on surface water, soil
surfaces, and structure surfaces. The air deposition modeling was conducted using AERMOD. A
description of the modeling and the deposition results is provided in Appendix F.2. Briefly, EPA used
the AERMOD module that assumes at least 10 percent of particles (by mass) are 10 micrometers (|im)
or larger. Asbestos fibers are not spheres and AERMOD assumes spheres in the deposition calculations
which affects settling velocity. EPA calculated the potential sphericity of asbestos particles using the
average diameter, aspect ratio, and percent by size bin provided by Wilson et al. (2008). The settings for
particle deposition modeling are summarized in Appendix F.2.6. Figure 3-8 and Figure 3-9 shows the
overall deposition pattern of asbestos fibers for specific and generic facilities by distance from source
for each OES. Each bar in Figure 3-8 and Figure 3-9 represents various facility types within each OES,
see Appendix F.3 for further details.
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Co-located General Population
General Population
10
30
I
60
100
1000
2500
5000
10000
Distance from Source (m)
¦ Handling Asbestos-Containing Building Materials During Maintenance, Renovation, and Demolition Activities Fugitive
¦ Waste Handling, Disposal, and Treatment Fugitive
¦ Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery Containing Asbestos Fugitive
¦ Handling Articles or Formulations that Contain Asbestos Fugitive
¦ Waste Handling, Disposal, and Treatment Stack
¦ Handling Articles or Formulations that Contain Asbestos Stack
¦ Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery Containing Asbestos Stack
Figure 3-8. Deposition of Asbestos Fibers from Specific Facilities by Distance for Each OES
1.00E+12
1.00E+11
1.00E+10
1.00E+09
^l.OOE+08
§, 1.00E+07
J 1.00E+06
!, 1.00E+O5
1)
Q 1.00E+04
1.00E+03
1.00E+02
1.00E+01
1.00E+00
Distance from Source (m)
¦ Fugitive Emissions Urban HE Met ¦ Fugitive Emissions Rural HE Met ¦ Fugitive Emissions Urban CT Met ¦ Fugitive Emissions Rural CT Met
¦ Stack Emissions Urban HE Met ¦ Stack Emissions Rural HE Met ¦ Stack Emissions Urban CT Met ¦ Stack Emissions Rural CT Met
Figure 3-9. Deposition of Asbestos Fibers from Generic Facilities by Distance for Each OES
Deposition rates of asbestos fibers are larger closer to the source and decrease farther away from the
source. This decreasing pattern is expected as asbestos fibers concentrations are higher closer to the
source (see Section 3.3.1.2). Based on the deposition pattern the concentrations of asbestos on surfaces
(soil, water, and structures) are also expected to be larger closer to the source. For asbestos to be a health
concern the fibers must be resuspended (re-released) from the surfaces it deposited onto via a
disturbance caused by meteorological events, human activities, or other events. The disturbance and
subsequent resuspension of asbestos fibers from surfaces act as a source of asbestos and similar patterns
of dispersion described in Section 3.3.1.2 and this modeled deposition rates section are expected.
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4 ENVIRONMENTAL RISK ASSESSMENT
4.1 Environmental Exposures
Asbestos - Environmental Exposures (Section 4.1):
Key Points
EPA evaluated the reasonably available information for environmental exposures to asbestos
following asbestos exposures. The following bullets summarize the key points of this section of the
draft Part 2 risk evaluation:
• Ingestion by aquatic and terrestrial organisms is the primary asbestos exposure route for
environmental hazard.
o Asbestos ingestion can occur via surface water or soil ingestion.
• U.S.-based and recent (<15 years) soil asbestos concentrations were not identified.
4.1.1 Approach and Methodology
The major environmental compartments for asbestos are ambient air, water, and soil. Environmental
asbestos concentrations of suspended particulates in ambient air in proximity to emitting sources are
summarized in Section 3.3.1 and 3.3.4. Surface water and soil concentrations are summarized in
Sections 3.3.2 and 3.3.3, respectively. Details about identification of information through systematic
review are included in Appendix F.3, Appendix F.4 and Appendix F.5.
Exposure to asbestos via ingestion is the most relevant exposure route for ecological organisms. In
particular, ingestion of asbestos in water is of concern for aquatic organisms. As described in Section
3.3.2.1, surface water monitoring data was available to estimate environmental concentrations of
asbestos. Asbestos exposure via soil is of concern for terrestrial organisms. The use of these data in
consideration of exposures to aquatic and terrestrial species is presented in Section 4.1.2 and 4.1.3,
respectively.
Inhalation and dermal exposures of asbestos to ecological organisms are not the primary exposure routes
of concern. As described in Section 4.2, environmental hazard data for ecological organisms does not
demonstrate effects from these exposure routes and thus risk is not expected.
4.1.2 Exposures to Ecological Species
The environmental concentrations of asbestos presented in Section 3.3 are relevant to the consideration
of exposure to aquatic and terrestrial species. Asbestos concentrations in water, soil, and air are highest
in close proximity to an asbestos source and asbestos concentrations decrease as you move away from
the source. Exposures to terrestrial species were not specifically considered as the hazard data do not
demonstrate relevant ecological apical assessment endpoints resulting from asbestos exposures (Section
4.2.2).
Aquatic organisms may be exposed to asbestos via untreated water sources that are not subject to
regulation for asbestos. EPA develops recommended aquatic exposure values for frequency and duration
of chemical exposures, such as asbestos, that are protective of human and aquatic life under section
304(a) of the Clean Water Act (CWA), although as of this time there are no nationally recommended
exposure values (aquatic life criteria) for aquatic organisms and asbestos under the CWA.
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Aquatic organisms may be exposed to asbestos in waterbodies though asbestos settles into sediments
and biosolids close to the source, as discussed in Section 2.2.2. Organisms close to the source of
asbestos have the potential to be exposed to higher concentrations of asbestos compared to those further
downstream from the source. Acute and chronic toxicity is possible for aquatic organisms exposed to
asbestos (Section 4.2).
4.1.3 Weight of Scientific Evidence Conclusions for Environmental Exposures
Limited monitoring data are available for aquatic and terrestrial species in the U.S. Monitoring data (<15
years old) is available within proximity of Superfund sites, though this would not be an appropriate
representation of asbestos concentrations in surface waters across the United States to be used in an
environmental hazard analysis. When considering older monitoring data or monitoring data from
international sources, there are uncertainties associated with using these data because it is unknown
whether those sampling sites are representative of current sites within the United States. EPA was also
unable to find recent (<15 years) asbestos soil concentrations within the United States to account for
naturally occurring asbestos and deposition from dispersion of human activity.
4.2 Environmental Hazards
Asbestos - Environmental Hazards (Section 4.2):
Key Points
EPA considered all reasonably available information identified by the Agency through its
systematic review process under TSCA to characterize environmental hazard endpoints for asbestos.
The following bullets summarize the key points of this section of the draft Part 2 risk evaluation:
• Aquatic species:
o The acute concentration of concern (COC) was calculated using the available 96-hour
lowest-observed-effect-concentration (LOEC) for an aquatic invertebrate (Corbicula sp.)
o Two chronic COCs were calculated using the available LOECs for an aquatic vertebrates
(Oryzias latipes) and aquatic invertebrates (Corbicula sp.)
o No aquatic plant hazard data with an overall quality determination of medium or high
were identified for asbestos
• Terrestrial species:
o No terrestrial vascular or non-vascular plant or soil invertebrate studies with an overall
quality determination of medium or high were identified for asbestos
o Terrestrial vertebrate studies were sorted by exposure route (e.g., dermal, oral,
inhalation); oral exposure studies were considered for hazard endpoints following
asbestos exposure
o EPA determined that the hazard endpoints identified for terrestrial vertebrates following
oral exposure to asbestos were not ecologically relevant
4.2.1 Approach and Methodology
During scoping, EPA reviewed potential environmental health hazards associated with asbestos. EPA
identified sources of environmental hazard data shown in Figure 2-10 of Scope of the Risk Evaluation
for Asbestos Part 2 (U.S. EPA. 2022b).
EPA completed the review of environmental hazard data/information sources during risk evaluation
using the data quality review evaluation metrics and the rating criteria described in the Draft Systematic
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Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances (U.S. EPA. 2021). Studies
were assigned overall quality determination (OQD) of high, medium, low, or uninformative. EPA
assigned metric ratings of high, medium, or low to 7 aquatic and 21 terrestrial toxicity studies; however,
only high and medium quality studies were used for hazard identification.
Environmental hazard was characterized in th q Risk Evaluation for Asbestos Part 1: Chrysotile Asbestos
(U.S. EPA. 2020c). In the Problem Formulation stage of Part 1, terrestrial pathways, including biosolids,
were eliminated as it was determined that EPA expects little to no risk to terrestrial organisms exposed
to [chrysotile] asbestos and the exclusion of ambient air and land (disposal) pathways. Terrestrial
pathways were included in the Part 2 Final Scope. The four aquatic toxicity studies included in Part 1
were also reviewed as acceptable studies for Part 2, along with additional toxicity studies found during
the review of literature and inclusion of terrestrial exposure pathways.
The Asbestos Part 1 Risk Evaluation only considered a single fiber type (chrysotile asbestos), while Part
2 expands upon the fiber types of consideration for hazard evaluation including amosite, tremolite,
crocidolite, anthophyllite, actinolite, and LAA. Terrestrial vertebrate studies were also evaluated for
hazard and were filtered by exposure route; dermal and inhalation studies were excluded from
evaluation for environmental hazard while oral exposure studies were considered relevant as on-topic
studies for review.
4.2.2 Aquatic Species Hazard
Toxicity to Aquatic Organisms
EPA assigned an overall quality determination of high or medium to six aquatic toxicity studies; low
quality studies were not considered for hazard identification in aquatic species. The high and medium
studies contained relevant aquatic toxicity data for Japanese medaka (Oryzias latipes), coho salmon
{Oncorhynchus kisutch), green sunfish {Lepomis cyanellus), fathead minnows (Pimephales promelas),
and Asiatic clams (Corbicula fluminea, Corbicula sp.). EPA identified and summarized these six aquatic
toxicity studies, displayed in Table 4-1, as the most relevant for quantitative assessment in Part 2 of the
Risk Evaluation. There were no studies with a high or medium overall quality determination identified
examining asbestos exposure to aquatic plants.
Aquatic Vertebrates
Three relevant fish studies were identified as acceptable with a quality rating of high or medium; the
species represented in these studies include Japanese medaka (Oryzias latipes), coho salmon
{Oncorhynchus kisutch), green sunfish {Lepomis cyanellus), and fathead minnows {Pimephales
promelas). The Risk Evaluation for Asbestos Part 1: Chrysotile Asbestos identified the Japanese
medaka, coho salmon, and green sunfish studies as acceptable and included them in the risk evaluation
(U.S. EPA. 2020c). In addition to the previous studies that were included in Part 1, an additional study
examining juvenile fathead minnows was identified for Part 2. The apical assessment endpoints included
mortality, growth, fiber uptake, histology, and behavior. All relevant studies evaluated were chronic
endpoints with chrysotile asbestos exposure; acute aquatic vertebrate studies were not identified for
asbestos.
Japanese medaka {Oryzias latipes) were exposed to chrysotile asbestos for 5 months; the no-observed-
effect-concentration (NOEC)ZLOEC (no observed effect concentration/lowest observed effect
concentration) for growth was reported as the most sensitive outcome at l.OxlO4 and l.OxlO6 fibers/L,
respectively (Belanger et al.. 1990). Coho salmon {Oncorhynchus kisutch) and green sunfish {Lepomis
cyanellus) were exposed to chrysotile asbestos for 86 and 67 days, respectively; behavioral and
histopathological analyses were reported. Behavioral stress was observed for coho salmon at 3.0><106
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fibers/L and 1.5><106 fibers/L for green sunfish (Belanger et al.. 1986c). Juvenile fathead minnows
(Pimephales promelas) were exposed to chrysotile asbestos for 30 days; the NOEC/LOEC for growth
was reported as the most sensitive endpoint at l.OxlO8 fibers/L (Belanger. 1985). EPA calculated the
geometric mean of the NOEC and LOEC in both Japanese medaka and fathead minnows, resulting in
chronic values (ChV) for both species (Table 4-1). There were no aquatic vertebrates studies examining
exposures to amphibole asbestos fibers or LAA.
Aquatic Invertebrates
EPA identified four relevant studies exposing aquatic invertebrates to chrysotile asbestos, and assigned
overall quality levels of medium or high. Siphoning activity, shell and tissue growth, fiber
uptake/accumulation, gill ultrastructure, larval release, and mortality of Asiatic clams (Corbicula sp.)
were monitored across the four studies. Exposure to asbestos ranges from 0 tolO8 fibers/L. In Part 1:
Chrysotile Asbestos, EPA reported on two of the four studies in Part 2 where Corbicula sp. were
exposed to chrysotile asbestos resulting in the reduced siphoning activity (U.S. EPA. 2020c). A decrease
in siphoning behavior to clams exposed to asbestos for 96 hours without food at 102 fibers/L; lower
siphoning in clams with food was suspected to be a result of satiation. Similar behaviors were observed
in chronic 30-day studies as observed in the acute 96-hour study for siphoning behavior. A decrease in
siphoning behavior to clams exposed to asbestos across all four reported studies as well as decreased
growth in clams exposed to asbestos at 106 fibers/L (LOEC) (Belanger et al.. 1987; Belanger et al..
1986a. b; Belanger. 1985).
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Table 4-1. Aquatic Organisms Environmental Hazard Studies Used for Asbestos
Duration
Test Organism
(Scientific Name)
Endpoint
Hazard
Values
(fibers/L)
Geometric
Mean
(fibers/L)fl
Effect
Fiber Type
Citation
(Overall Quality
Determination)
Aquatic Invertebrates
Chronic
Asiatic clam
(Corbicula
sp J Corbicula
fluminea)
30 days
LOEC
102fe
104c
Reduced siphoning6; Growthc
Chrysotile
(Belanser et al..
1986a) (High);
(Belanser et al..
1986b) (High);
(Belanser et al..
1987) (High);
Acute
Asiatic clam
('Corbicula sp.)
96-hour
LOEC
102
-
Reduced Siphoning
Chrysotile
(Belanser et al..
1986b)(High)
Aquatic Vertebrates
Japanese Medaka
('Oryzias latipes)
13 days to 5
months
LOEC
104
106l#
105
Hatchability; mortality (eggs,
larvae); grow threproduction
Chrysotile
(Belanser et al..
1990) (High)
Chronic
Coho salmon
('Oncorhynchus
kisutch)
40 to 86
days
3.0E6
Behavioral
Chrysotile
(Belanser et al..
Green Sunfish
(Lepomis
cyane litis)
52 to 67
days
1.5E6
Behavioral
Chrysotile
1986c) (High)
Fathead minnows
(Pimephales
promales)
30 days
LOEC
10E8
10E7
Growth/developmental
Chrysotile
(Belanser. 1985)
(High)
11 Geometric mean of definitive values only
h Hazard value for effects on reduced siphoning to Asiatic clam
c Hazard value for effects on growth to Asiatic clam
d Hazard value for effect on growth to Japanese Medaka
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4.2.3 Terrestrial Species Hazard
EPA assigned an overall quality determination of high or medium to 15 terrestrial acceptable studies.
These studies contained relevant terrestrial toxicity data for three rat (Rattus norvegicus) strains (F344,
Sprague-Dawley, and Wistar Han), mice (Mas musculus), golden Syrian hamsters (Mesocricetus
aiiratus), guinea pigs (Caviaporcellus), and white leghorn fowls (Gallus galhis domesticus). No
terrestrial invertebrate or plant studies with an overall quality determination of high or medium were
identified.
Terrestrial Vertebrates
Hazard to terrestrial vertebrates was not assessed in The Risk Evaluation for Asbestos Part 1: Chrysotile
Asbestos (U.S. EPA. 2020c). At the time Part 1 was developed, pathways were excluded if covered by
existing EPA statutes, so the ambient air and land (disposal) pathways were excluded. Pathways are no
longer excluded based on existing EPA statutes.
In Asbestos Part 2, non-human animal studies were included for consideration with exposure to asbestos
via the oral exposure route. Authors reported ecologically relevant hazard endpoints including mortality,
reproductive effects, and impacts on growth/development, as well as ADME. Cancer endpoints were
evaluated and reported across studies however, cancer is not an ecologically relevant endpoint, thus not
considered further for ecological hazard. Study organisms were exposed to chrysotile, amosite,
tremolite, crocidolite, and anthophyllite fibers across the 15 studies.
There is not a relevant connection to a COU and exposures to environmental species with population
effects. Asbestos did not significantly affect mortality across the high and medium studies for rats, mice,
hamsters, guinea pigs, and fowls exposed to asbestos fibers. Growth was monitored across studies; no
significant impact on growth was observed across the studies. Two studies reported smaller growth of
offspring but it was not reported as significant after statistical analysis of the results (NTP. 1988;
McConnell et al.. 1983). Fertility and litter size were reported across two studies as reproductive
endpoints; this did not yield significant differences between organisms exposed to asbestos and controls
(NTP. 1985; McConnell et al.. 1983). Therefore, no ecologically relevant effects were reported for
terrestrial organisms and hazard could not be evaluated due to a lack of applicable data.
4.2.4 Environmental Hazard Thresholds
EPA calculated hazard thresholds to identify potential concerns to aquatic species based on weighing the
scientific evidence and selection of the appropriate toxicity value from the integrated data to use for
hazard thresholds. 0 provides more details about how EPA weighed the scientific evidence.
For aquatic species, hazard was estimated by calculating a concentration of concern (COC) for a hazard
threshold. COCs can be calculated using a deterministic method by dividing a hazard value by an
assessment factor (AF) according to EPA methods (U.S. EPA. 2016b. 2013. 2012) and Equation 4-1.
Equation 4-1.
COC = toxicity value ^ AF
Concentration of Concern (COC) for Aquatic Toxicity
Acute COC: For the acute COC, EPA used the 96-hour LOEC for Corbicida sp. where decreased
siphoning activity was observed for adult clams that were not fed; decreased siphoning was observed at
concentrations of asbestos ranging 102-108 fibers/L from Table 4-1. EPA applied an assessment factor
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(AF) of 5 to the lowest observed effect concentration of 102 fibers/L chrysotile asbestos (Belanger et al..
1986a).
COC = 102 fibers/L - 5
COC = 20 fibers/L chrysotile asbestos
Chronic COC: EPA calculated two chronic aquatic COCs, using the most sensitive vertebrate and
invertebrate available data. Decreased siphoning was reported for clams (Corbicula sp.) at 102 fibers/L
chrysotile asbestos. An AF of 10 was applied to the LOEC (Belanger et al.. 1986a).
COC = 102 fibers/L - 10
COC = 10 fibers/L chrysotile asbestos
EPA calculated a second chronic COC and used the Japanese medaka (Oryzias latipes) geometric mean
of 105 fibers/L chrysotile asbestos from Table 4-1, with the application of an AF of 10. Japanese medaka
were reported to have decreased growth and increased mortality at the LOEC of 106 fibers/L (NOEC of
104 fibers/L) (Belanger et al.. 1990).
COC = 105 fibers/L - 10
COC = 10,000 fibers/L chrysotile asbestos
A COC was calculated for both aquatic vertebrates and invertebrates to be protective of the
physiological differences between mollusks and fish (e.g., cephalopod mollusks use their siphuncle to
move water throughout their chambers which differs from the potential exposure fish may have in their
mouths or gills). This approach acknowledges the increased uncertainty, detailed in Section 4.2.6.1,
associated with the limited data landscape for asbestos environmental hazard.
For terrestrial species, EPA estimates hazard by using a hazard value for soil invertebrates, a
deterministic approach, or calculating a toxicity reference value (TRV) for mammals. There were no
reasonably available mammalian toxicity studies with apical assessment endpoints and EPA was unable
to model mammalian hazard values for asbestos, therefore a TRV was not calculated.
4.2.5 Summary of Environmental Hazard Assessment
For acute aquatic exposures to chrysotile asbestos, the 96-hour LOEC value was 102 fibers/L for
Corbicula sp., from one high quality study (Belanger et al.. 1986a). For chronic aquatic exposures to
chrysotile asbestos, EPA calculated two COCs; the invertebrate COC and vertebrate COC. EPA
calculated both an invertebrate and vertebrate chronic COC due to the physiological differences between
clams and fish. The chronic invertebrate COC was calculated using the LOEC for Corbicula sp.
exhibiting decreased siphoning at 102 fibers/L for Corbicula sp., from one high quality study (Belanger
et al.. 1986a). Three studies reported environmental hazards on clams, cited in Table 4-1. EPA
calculated the chronic aquatic vertebrate COC by applying an AF to the geometric mean of the NOEC
and LOEC reported for Japanese medaka (Belanger et al.. 1990). Available aquatic studies did not
include asbestos fiber types outside of chrysotile. No studies were available for aquatic or terrestrial
plants, and there were no high or medium quality studies available for terrestrial invertebrates. Relevant
ecological endpoints with reported hazard values were not available for terrestrial vertebrates.
Clams were the principal organism for aquatic invertebrates in the available studies. According to
ATSDR, clams that are located in asbestos-contaminated areas (e.g., areas with shore-line erosion) may
accumulate asbestos fibers. If asbestos fibers are found in the sediments and/or water, clams may
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become contaminated by uptaking the fibers with their siphuncle and this is likely where the fibers
would concentrate while siphoning (ATSDR. 2014). In the Corbicula sp. studies discussed in Section
4.2, authors observed decreased siphoning behavior in clams exposed to asbestos fibers at
concentrations as low as 102 fibers/L; EPA utilized this hazard value to calculate an acute COC of 20
fibers/L and a chronic COC of 10 fibers/L (Table 4-2).
Table 4-2. Environmental Hazard Thresho
ds for Aquatic Environmental Toxicity
Environmental Aquatic Toxicity
Hazard Value
(fibers/L)
Assessment Factor
(AF)
COC
(fibers/L)
Acute aquatic exposure: LOEC
102
5
20
Chronic aquatic exposure: invertebrate
(mollusk)
102
10
10
Chronic aquatic exposure: vertebrate (fish)
106
10
105
When asbestos enters water, it will settle into sediments and biosolids (see Section 2.2.2). Due to
sediment settling, it is unlikely that asbestos will accumulate (or bioaccumulate) in terrestrial or aquatic
organisms. Limited data are available to support accumulation within organisms. Environmental hazard
data suggests that at concentrations of asbestos >102 fibers/L, hazard effects are reported for organisms.
As explained in Section 3.3.4, concentrations and deposition of asbestos fibers will be higher closer to
the source of asbestos; therefore, organisms closer to an asbestos source may experience a greater risk
than organisms further away from the source due to decreasing concentrations the further away from the
source. The concentration of suspended asbestos fibers in water is reported to decrease by more than 99
percent in water reservoirs (Section 2.2.2), supporting the evidence from Asbestos Part 1 describing how
asbestos will settle into sediments.
4.2.6 Weight of Scientific Evidence Conclusions for Environmental Hazards
EPA/OPPT uses several considerations when weighing and weighting the scientific evidence to
determine confidence in the environmental hazard data. These considerations include the quality of the
database, consistency, strength, and precision, biological gradient/dose response, and relevance
(Table Apx G-l). This approach is consistent with the Draft Systematic Review Protocol Supporting
TSCA Risk Evaluations for Chemical Substances (U.S. EPA. 2021). Table 4-3 summarizes how these
considerations were ranked for each environmental hazard threshold. Overall, EPA considers the
evidence for aquatic hazard thresholds moderate and terrestrial vertebrate hazard thresholds
indeterminate. A more detailed explanation of the weight of scientific evidence, uncertainties, and
overall confidence is presented in Appendix G.2.1.
4.2.6.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
Environmental Hazard Assessment
Quality of the Database; and Strength (Effect Magnitude) and Precision
All the studies used to calculate COCs (aquatic fish and invertebrates) received a high data quality level
from the systematic review data quality evaluation. Effect size was reported for aquatic studies using
LOECs.
Consistency
For aquatic invertebrate species, the behavior effect of reduced siphoning was reported across three
studies with LOECs for both acute and chronic durations, therefore EPA assigned robust confidence in
the consistency consideration for the acute and chronic aquatic assessments. The acute clam study
utilized two groups of fed (n = 7) and two groups of unfed clams (n = 5). Behavior was monitored and
reduced siphoning was observed for clams in the unfed groups. One exposure group (n = 5) of clams
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was used in the chronic study. Behavioral effects were consistent between acute and chronic clam
studies. Juvenile Japanese medaka used in calculating the chronic vertebrate COC were separated into
five exposure groups in triplicate (n = 15). Growth effects between chronic vertebrate and invertebrates
differed, which supports the decision to calculate two COCs due to the physiological differences among
the species tested.
Biological Gradient/Dose-Response
LOECs were reported for clam and medaka studies; effects were reported across doses.
Biological Relevance
Behavioral effects were consistent across acute and chronic clam studies. Japanese medaka and fathead
minnow studies both reported growth impacts due to asbestos exposure. Behavioral effects were also
consistent across green sunfish and coho salmon.
Physical/Chemical Relevance
Asbestos is a solid/fiber that does not degrade and lacks solubility. Therefore, asbestos can accumulate
in sediment where sediment-dwelling organisms may be exposed to the fibers or exposure may occur in
the water column when the fibers are disturbed. Fibers will settle and concentrations decrease the further
away from the source the organisms reside.
Environmental Relevance
Additional uncertainty is associated with the concentrations of asbestos used in the environmental
hazard assessments. The lowest concentration utilized in the hazard studies was 102fibers/L asbestos,
while concentrations in the environment can vary with distance from the source of asbestos.
Apical assessment endpoints (i.e., growth, mortality) were not reported for terrestrial studies and
therefore the overall confidence threshold was indeterminate.
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Table 4-3. Evidence Table Summarizing the Overall Confidence Derived from Hazard Thresholds
Types of Evidence
Quality
of the
Database
Consistency
Strength and
Precision
Biological
Gradient/Dose-
Response
Relevance"
Hazard
Confidence
Aquatic
Acute Aquatic Assessment
+++
++
++
+
+
Moderate
Chronic Aquatic Assessment
+++
++
++
+
+
Moderate
Terrestrial
Mammalian Assessment
+
++
+
N/A
N/A
Indeterminate
11 Relevance includes biological, physical/chemical, and environmental relevance.
+ + + Robust confidence suggests thorough understanding of the scientific evidence and uncertainties. The supporting weight of scientific evidence
outweighs the uncertainties to the point where it is unlikely that the uncertainties could have a significant effect on the hazard estimate.
+ + Moderate confidence suggests some understanding of the scientific evidence and uncertainties. The supporting scientific evidence weighed against
the uncertainties is reasonably adequate to characterize hazard estimates.
+ Slight confidence is assigned when the weight of scientific evidence may not be adequate to characterize the scenario, and when the assessor is making
the best scientific assessment possible in the absence of complete information. There are additional uncertainties that may need to be considered.
Indeterminate is assigned when there is no available data for which to evaluate potential hazard.
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4.3 Environmental Risk Characterization
Asbestos - Environmental Risk Characterization (Section 4.3):
Key Points
EPA evaluated the reasonably available information to support environmental risk characterization.
The following bullets summarize the key points of this section of the draft Part 2 risk evaluation:
• RQs (risk quotients) are unable to be calculated for asbestos
o Limited aquatic exposure data did not yield numbers for monitoring data outside of
Superfund sites, therefore a representative exposure was unavailable
o Environmental hazard to terrestrial species was not quantified due to a lack of data with
apical assessment endpoints
EPA considered fate, exposure, and environmental hazard to consider the environmental risk of
asbestos. EPA identified hazards to aquatic species via water and sediment and calculated a COC based
on the available studies. However, EPA did not estimate risks to aquatic species due to a lack of relevant
environmental exposure concentrations. EPA did not estimate risk to terrestrial species from asbestos
due to the lack of apical assessment endpoints available to assess hazard and risk.
The physical chemical properties of asbestos limit the potential for exposure to aquatic species. Asbestos
is classified as naturally occurring mineral silicate fibers, see Section 2.1. Therefore, according to the
physical chemical properties, asbestos fibers are not expected to degrade in the environment. As
described in Section 2.2.2., once asbestos enters water it will settle into sediments and biosolids.
Concentrations of asbestos will be higher in water and sediment closer to the source of asbestos. Aquatic
organisms located close to the source of asbestos may be at risk for asbestos exposure, although this
does not account for hazard and risk at a population level as organisms further downstream from the
source of asbestos will not be exposed to the same concentrations of asbestos.
4,3.1 Risk Characterization Approach and Summary
EPA characterizes the environmental risk of chemicals using risk quotients (RQs) (U.S. EPA. 1998;
Barnthouse et al.. 1982). The RQ is defined in Equation 4-2:
Equation 4-2.
RQ = Predicted Environmental Concentration / Hazard Threshold
EPA was unable to quantitatively calculate an RQ for asbestos due to a lack of relevant aquatic exposure
data. As shown in Table 3-13, recent monitoring data for asbestos in water (2000 to present) exists for
Superfund sites (e.g., Libby Asbestos Site, Libby, MT or BoRit Asbestos Site, Ambler, Pennsylvania).
Using Superfund data to calculate an RQ would not be representative to populations of organisms that
may be exposed to asbestos. Additionally, exposure is not expected under the COUs for asbestos for
terrestrial and aquatic organisms. A TRV was not calculated for terrestrial hazard due to limited
terrestrial toxicity data and no apical endpoints in available studies. Without predicted environmental
concentrations, EPA was unable to calculate an RQ using the above equation.
Aquatic environmental hazard studies were characterized in Section 4.2, with sublethal acute effects
observed at 102fibers/L chrysotile asbestos and sublethal chronic effects observed at 106fibers/L
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2610 chrysotile asbestos. Hazard endpoints included reproductive and behavioral effects for aquatic exposures
2611 (Table 4-2). Aquatic hazard data was not available for other fiber types, outside of chrysotile asbestos.
2612
2613 In accordance with the Asbestos Part 1 Risk Evaluation, EPA concludes that there is very limited
2614 potential for asbestos exposures to aquatic or sediment-dwelling organisms and risk is not observed from
2615 exposure to asbestos fibers (U.S. EPA. 2020c).
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2616 5 HUMAN HEALTH RISK ASSESSMENT
2617
2618 5.1 Human Exposures
2619
Asbestos - Human Exposures (Section 5.1):
Key Points
EPA evaluated all reasonably available information for the following exposure categories:
occupational, consumer, and general population. The following bullets summarize the key points of
this section of the draft Part 2 risk evaluation:
• Inhalation is the primary route for all human exposures considered under this Part 2 of the risk
evaluation. Oral exposure was not assessed in depth, because ingestion of low concentration of
respirable fibers in mucus shows inconclusive associations with health effects. Dermal
exposure was not assessed due to lack of systemic dermal penetration.
• Systematic review was conducted to identify the reasonably available information relevant for
consideration in the quantitative human health approach; however, no cancer or non-cancer
epidemiologic studies from oral or dermal exposures that support dose-response analysis were
identified.
• Occupational exposures through inhalation were estimated using inhalation monitoring data to
calculate high-end and central tendency exposure values for each relevant occupational
exposure scenario. Occupational exposure to asbestos varied by several orders of magnitude
based on activity with the highest number of exposed workers involved in maintenance,
renovation, and demolition, and firefighting and other disaster response activities.
• Take-home exposures to asbestos through inhalation of fibers loaded onto clothing/garment
during some occupational/DIY activity and subsequent garment handling at home were
calculated for each COU. Exposures varied by orders of magnitude for high-end and central
tendency estimates due to large differences between occupational activities exposure
concentrations for those scenarios.
• The consumer DIY activity-base scenarios from inhalation exposure concentrations related to
removal of asbestos containing products are generally larger than activities related to
maintaining, cutting, or moving asbestos containing materials.
• The general population inhalation exposure to asbestos fibers released to ambient air from
occupational activities such as demolitions, firefighting, and removal of asbestos containing
materials shows exposure concentrations are higher closer to the source and decrease by a few
orders of magnitude beyond the co-located general population distances (100 m).
• EPA explored aggregation of risks across populations and COUs and found that people
engaged in various asbestos releasing activities, may those be occupational, DIY, take-home,
or from releases to the environment and subsequent indoor infiltration have higher exposures
and potential risks.
2620
2621 Evaluated Exposure Routes
2622 Inhalation is the primary route of occupational and non-occupational exposure to released friable
2623 asbestos fibers evaluated in this Part 2 of the risk evaluation. Although ingestion of respirable fibers can
2624 occur via mucus in the respiratory tract, studies aiming to assess the adverse health effects from asbestos
2625 ingestion have found low correlations or undecisive results (ATSDR. 2012: Polissar et al.. 1983).
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Asbestos fibers ingested via the oral pathway will pass the digestive system and be excreted within a
few days, while small fibers may migrate to blood or other tissues before urinary elimination. Therefore,
EPA does not consider the ingestion of asbestos fibers as a relevant exposure pathway for establishing
risks related to asbestos exposure. Similarly, dermal exposures are not assessed for workers or ONUs in
Part 2 of the Draft Risk Evaluation for Asbestos. The basis for excluding this route is that asbestos exists
in a solid/fiber physical form only, and the size and lack of solubility of an asbestos fiber prevents
systemic dermal penetration. While asbestos may deposit on open/unprotected skin, it will not absorb
into the body through the protective outer skin layers. Therefore, a dermal dose resulting from dermal
exposure is not expected.
Human Exposure Concentrations
For each exposure pathway, low-end (LE), central tendency (CT), and high-end (HE) risk from
inhalation exposure concentrations were estimated. EPA's Human Exposure Guidelines defined central
tendency exposures as "an estimate of individuals in the middle of the distribution." It is anticipated that
these estimates apply to most individuals in the United States. HE exposure estimates are defined as
"plausible estimate of individual exposure for those individuals at the upper end of an exposure
distribution, the intent of which is to convey an estimate of exposure in the upper range of the
distribution while avoiding estimates that are beyond the true distribution." It is anticipated that these
estimates apply to some individuals, particularly those who may live, work, and recreate near facilities
with elevated concentrations.
Sentinel and Aggregate Considerations
Section 2605(b)(4)(F)(ii) of TSCA requires EPA, as a part of the risk evaluation, to describe whether
aggregate or sentinel exposures under the conditions of use were considered and the basis for their
consideration. EPA defines sentinel exposure as "the exposure to a single chemical substance that
represents the plausible upper bound of exposure relative to all other exposures within a broad category
of similar or related exposures (40 CFR 702.33)." In terms of this risk evaluation, EPA considered
sentinel exposures by considering risks to populations who may have upper bound exposures; for
example, workers and ONUs who perform activities with higher exposure potential, or consumers who
have higher exposure potential (e.g., those involved with do-it-yourself projects) or certain physical
factors like body weight or skin surface area exposed. EPA characterized high-end exposures in
evaluating exposure using both monitoring data and modeling approaches. Where statistical data are
available, EPA typically uses the 95th percentile value of the available data set to characterize high-end
exposure for a given condition of use. For consumer and bystander exposures, EPA characterized
sentinel exposure through a "high-intensity use" category based on both product and user-specific
factors. The aggregate analysis considers the aggregation of scenarios for high intensity users when the
individual scenarios do not exceed risk benchmarks, Section 5.1.5.
5.1.1 Occupational Exposures
The following subsections briefly describe EPA's approach to assessing occupational exposures and
results for each condition of use assessed. For additional details on development of approaches and
results refer to Appendix E.
5.1.1.1 Approach and Methodology
As described in the Scope of the Risk Evaluation for Asbestos Part 2 (U.S. EPA. 2022b). for each
condition of use, EPA endeavors to distinguish exposures among potentially exposed employees for
workers and occupational non-users (ONUs). Normally, a primary difference between workers and
ONUs is that workers may handle asbestos and have direct contact with the substance, while ONUs are
working in the general vicinity of workers but do not handle asbestos and do not have direct contact with
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asbestos being handled by the workers. As discussed in Section 3.1.1, EPA established OESs to assess
the exposure scenarios more specifically within each COU. Table 3-1 provides a crosswalk between
COUs and OESs. Also, EPA identified job types and categories for workers and ONUs and developed
Similar Exposure Groups (SEGs) for a few of the OESs where more detailed information was available
to split between higher exposure-potential workers and lower exposure-potential workers.
For the OESs that were split into SEGs, higher exposure-potential workers are defined as workers whose
activities may directly generate friable asbestos through actions such as cutting, grinding, welding, or
tearing asbestos-containing materials; lower exposure-potential workers are workers who are not
expected to generate friable asbestos but may come into direct contact with friable asbestos while
performing their required work activities. ONUs do not directly handle asbestos or asbestos-containing
products but are present during their work time in an area where asbestos or an asbestos-containing
product is or may be present. Examples of ONUs include supervisors/managers, building inspectors,
ship captains and other marine personnel, and truck drivers who might access the work area or transport
materials but do not perform tasks directly with asbestos or asbestos containing products.
EPA identified relevant inhalation exposure monitoring data for all of the given OESs. The quality of
this monitoring data was evaluated using the data quality review evaluation metrics and the rating
criteria described in the Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for
Chemical Substances (U.S. EPA. 2021). Relevant data were assigned an overall quality level of high,
medium, or low. In addition, EPA established an overall confidence for the data when integrated into the
occupational exposure assessment. EPA considered the assessment approach, the quality of the data and
models, and uncertainties in assessment results to assign an overall confidence level of high, medium, or
low.
In th q Risk Evaluation for Asbestos Part I: Chrysotile Asbestos (U.S. EPA. 2020c). EPA only evaluated
inhalation exposures to workers and ONUs in association with chrysotile asbestos manufacturing
(import), processing, distribution and use in industrial applications and products. Part 2 of the risk
evaluation covers exposure to industrial and commercial legacy uses and associated disposals of all
forms of asbestos, as well as consideration of talc and vermiculite products that may contain asbestos.
The physical condition of asbestos is an important factor when considering the potential human
pathways of exposure. Several of the asbestos-containing products identified as COUs of asbestos are
not friable as intact products; however, the products can be made friable due to physical and chemical
wear over time. Exposures to asbestos can potentially occur via all routes; however, EPA anticipates that
the most likely exposure route is inhalation for workers and ONUs.
Where monitoring data were reasonably available, EPA used these data to characterize central tendency
and high-end inhalation exposures. In cases where no ONU sampling data are available, EPA typically
assumes that ONU inhalation exposure is either comparable to area monitoring results or assumes that
ONU exposure is likely lower than workers. EPA identified monitoring data for ONUs for three of the
four OESs where ONU exposure is assessed. For the Waste Handling and Disposal OES, EPA did not
have monitoring data to estimate inhalation exposure for ONUs. In this case, exposure for ONUs was
addressed using the central tendency for estimates of worker inhalation exposure. As noted in Section
5.1, dermal exposures are not assessed for workers or ONUs because the expected physical form of
asbestos is only the solid/fiber phase. While asbestos may deposit on open/unprotected skin, it will not
absorb into the body through the protective outer skin layers.
EPA considered two issues unique to asbestos, when compared to other chemicals for which EPA
developed TSCA risk evaluations. One issue is the possibility of asbestos fibers settling to surfaces and
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subsequently becoming resuspended into the workplace air. The extent to which this process occurs is
assumed to be reflected in the sampling data that EPA considered for each COU. The second unique
issue for asbestos is that it can be found in friable and non-friable materials; and the friability of the
materials has direct bearing on asbestos releases to the air. This issue is also presumably reflected in the
sampling data (i.e., asbestos in friable materials has a greater likelihood of being detected in the air
samples, as compared to asbestos in non-friable materials).
The occupational exposure assessment of each OES comprises the following components:
• Process Description: A description of the OES, including the role of asbestos in the use; process
vessels, equipment, and tools used during the OES; and descriptions of the worker activities,
including an assessment for potential points of worker exposure.
• Worker Activities: Activities in which workers may be potentially exposed to asbestos.
• Number of Establishments: Estimated number of establishments with workers and ONUs that
use asbestos for the given OES. Workers and ONUs from one establishment may perform work
activities at various sites for the following OES: Handling Asbestos-Containing Building
Materials During Maintenance, Renovation, and Demolition Activities; Handling of Asbestos-
Containing Building Materials during Firefighting or Other Disaster Response Activities.
• Number of Potentially Exposed Workers: Estimated number of workers, including ONUs,
who could potentially be exposed to asbestos for the given OES.
• Occupational Inhalation Exposure Results: EPA used exposure monitoring data provided by
industry and/or available in the peer-reviewed literature, when it was available, to assess
occupational inhalation exposures. In all cases, EPA synthesized the reasonably available
information and considered limitations associated with each data set. In Section 5.1.1.2, EPA
reports central tendency and high-end estimates for exposure distribution derived for workers
and for ONUs for each OES and Section 5.1.4.1 presents the strengths, limitations, assumptions,
and uncertainties associated with these exposure estimates. Figure 5-1 displays the general
approaches used to develop occupational exposure estimates for each OES. Inhalation exposure
estimates were generated by analyzing monitoring data that was found in NIOSH Health Hazard
Evaluations (HHE's), Occupational Safety and Health Administration (OSHA) Chemical
Exposure Health Data (CEHD) or were provided by industry. Estimates for the number of
workers and ONUs potentially exposed were generally estimated by analyzing Occupational
Employment Statistics data from the Bureau of Labor Statistics (BLS) and data from the U.S.
Census' Statistics of U.S. Businesses for relevant NAICS codes. Further discussion on the
approaches used for each occupational exposure assessment is provided in Appendix E.
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Figure 5-1. Approaches Used for Each Component of the Occupational Assessment for Each OES
TRI = Toxics Release Inventory; NEI = National Emissions Inventory; CDR = Chemical Data Reporting; BLS =
Bureau of Labor Statistics; NIOSH = National Institute of Occupational Safety and Health; OSHA = Occupational
Safety and Health Administration; NFPA = National Fire Protection Association
Appendix E provides a summary of EPA's estimates for the total exposed workers and ONUs for each
OES. To prepare these estimates, EPA first attempted to identify North American Industrial
Classification (NAICS) codes associated with each OES. For these NAICS codes, EPA then reviewed
Standard Occupational Classification (SOC) codes from BLS and classified relevant SOC codes as
workers or ONUs. All other SOC codes were assumed to represent occupations where exposure is
unlikely. EPA also estimated the total number establishments associated with the NAICS codes
previously identified based on data from the U.S. Census Bureau.
EPA then estimated the average number of workers and ONUs potentially exposed per establishment by
dividing the total number of workers and ONUs by the total number of establishments. For the OES for
Firefighting and Other Disaster Response Activities, EPA used data provided by the National Fire
Protection Association (NFPA) in order to estimate the number of firefighters (both career and
volunteer), the number of fire departments, and the number of responders per structure fire (NFPA.
2022b. 2012). Because all workers in firefighting and disaster response may be highly exposed, EPA
assumed that there are only workers and that there are no ONUs for the OES. Additional details on
EPA's approach and methodology for estimating the number of establishments using asbestos and the
number of workers and ONUs potentially exposed to asbestos can be found in Appendix E.
5.1.1.1.1 Consideration of Engineering Controls and Personal Protective
Equipment
OSHA requires employers to utilize the hierarchy of controls to address hazardous exposures in the
workplace. The hierarchy of controls prioritizes the most effective measures to address exposure; the
first of which is to eliminate or substitute the harmful chemical (e.g., use a different process, substitute
with a less hazardous material), thereby preventing or reducing exposure potential. Following
elimination and substitution, the hierarchy prioritizes engineering controls to isolate employees from the
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hazard (e.g., source enclosure, local exhaust ventilation systems), followed by administrative controls, or
changes in work practices to reduce exposure potential. Administrative controls are policies and
procedures instituted and overseen by the employer to prevent worker exposures. As the last means of
control, the use of PPE (e.g., respirators, gloves) is required, when the other feasible control measures
cannot reduce workplace exposure to an acceptable level.
OSHA Respiratory Protection and Asbestos Standards
OSHA has standards that are applicable to occupational exposure to asbestos including the Respiratory
Protection Standard (29 CFR 1910.134); and the Asbestos Standard for general industry (29 CFR
1910.1001) construction (29 CFR 1926.1101), and shipyards (29 CFR 1915.1001). These standards
have multiple provisions that are highlighted below.
OSHA's Respiratory Protection Standard (29 CFR 1910.134) requires employers to provide respiratory
protection whenever it is necessary to protect the health of the employee from contaminated or oxygen
deficient air. This includes situations where respirators are necessary to protect employees in
an emergency. Employers must follow the hierarchy of controls that requires the use of engineering and
work practice controls, where feasible. Only if such controls are not feasible or while they are being
implemented may an employer rely on a respirator to protect employees. Respirator selection provisions
are provided in CFR 1910.134(d) and require that appropriate respirators be selected based on the
respiratory hazard(s) to which the worker will be exposed and workplace and user factors that affect
respirator performance and reliability. Assigned protection factors (APFs) are provided in Table 1 under
CFR 1910.134(d)(3)(i)(A) (see also Table 5-1). APFs refer to the level of respiratory protection that a
respirator or class of respirators is expected to provide to employees when the employer implements a
continuing, effective respiratory protection program.
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Table 5-1. Assigned Protection Factors for Respirators in OSHA Standard 29 CFR 1910.134eg
Type of Respirator"6
Quarter
Mask
Half
Mask
Full
Facepiece
Helmet/Hood
Loose-Fitting
Facepiece
1. Air-Purifying Respirator
5
10c
50
2. Powered Air-Purifying Respirator (PAPR)
50
1,000
25/l,000'#
25
3. Supplied-Air Respirator (SAR) or Airline Respirator
• Demand mode
W
50
• Continuous flow mode
5 Of
1,000
25/l,000'#
25
• Pressure-demand or other positive-
pressure mode
5Qf
1,000
4. Self-Contained Breathing Apparatus (SCBA)
• Demand mode
W
50
50
• Pressure-demand or other positive-
pressure mode
10,000
10,000
11 Employers may select respirators assigned for use in higher workplace concentrations of a hazardous substance for
use at lower concentrations of that substance, or when required respirator use is independent of concentration.
h The assigned protection factors are only effective when the employer implements a continuing, effective respirator
program as required by 29 CFR 1910.134, including training, fit testing, maintenance, and use requirements.
c This APF category includes filtering facepieces and half masks with elastomeric facepieces.
d The employer must have evidence provided by the respirator manufacturer that testing of these respirators
demonstrates performance at a level of protection of 1,000 or greater to receive an APF of 1,000. This level of
performance can best be demonstrated by performing a workplace protection factor (WPF) or simulated workplace
protection factor (SWPF) study or equivalent testing. Absent such testing, all other PAPRs and SARs with
helmets/hoods are to be treated as loose-fitting facepiece respirators and receive an APF of 25.
'' These APFs do not apply to respirators used solely for escape. For escape respirators used in association with
specific substances covered by 29 CFR 1910 subpart Z, employers must refer to the appropriate substance-specific
standards in that subpart. Escape respirators for other IDLH atmospheres are specified by 29 CFR 1910.134(d)(2)(ii).
' These respirators are not common.
g Respirators with bolded APFs satisfy the OSHA requirements for asbestos and an appropriate respirator should be
selected based on the air concentration. Filtering facepiece respirators do not satisfy OSHA requirements for
protection against asbestos fiber.
OSHA's asbestos standards also include respiratory protection provisions found at 29 CFR
1910.1001(g) for general industry, 29 CFR 1926.1101(h) for construction, and 29 CFR 1915.1001(g)
for shipyards. The respiratory protection provisions in these standards require employers to provide each
employee with an appropriate respirator that complies with the requirements outlined in the provision. In
the general industry standard, paragraph (g)(2)(ii) requires employers to provide an employee with a
tightfitting, powered air-purifying respirator (PAPR) instead of a negative pressure respirator selected
according to paragraph (g)(3) when the employee chooses to use a PAPR and it provides adequate
protection to the employee. In addition, paragraph (g)(3) of the general industry standard states that
employers must not select or use filtering facepiece respirators for protection against asbestos fibers.
Therefore, filtering facepiece respirators were not included in Table 5-1. Based on the general industry
standards for handling asbestos, the following PPE should not be used as protection against asbestos
fibers: filtering facepieces (N95), quarter masks, helmets, hoods, and loose fitting facepieces. OSHA's
29 CFR 1910.1001(g)(3)(ii) also indicates that high-efficiency particulate air (HEPA) filters for PAPR
and non-powered air-purifying respirators should be provided.
APFs are intended to guide the selection of an appropriate class of respirators to protect workers after a
substance is determined to be hazardous, after an occupational exposure limit is established, and only
when the occupational exposure limit is exceeded after feasible engineering, work practice, and
administrative controls have been put in place. For asbestos, the employee permissible exposure limit
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(PEL) is 0.1 fibers per cubic centimeter (f/cc) as an 8-hour, time-weighted average (TWA) and/or the
excursion limit of 1.0 f/cc averaged over a sampling period of 30 minutes.
Using the OSHA PEL for asbestos of 0.1 f/cc, a half-mask negative pressure HEPA filtered facepiece
(when fitted properly) can provide protection in atmospheres with up to 1.0 f/cc [0.1 f/cc multiplied by
the APF of 10],
Only the respirator types and corresponding APFs bolded in Table 5-1 meet the OSHA requirements for
asbestos. The specific respiratory protection required in any situation is selected based on air monitoring
data. OSHA specifies that the Maximum Use Concentration (MUC) be calculated to assess respirator
selection. The MUC is the maximum amount of asbestos that a respirator can handle from which an
employee can be expected to be protected when wearing a respirator. The APF of the respirator or class
of respirators is the amount of protection that it provides the worker compared to not wearing a
respirator. The permissible exposure limit for asbestos (0.1 f/cc) sets the threshold for respirator
requirements. The MUC can be determined by multiplying the APF specified for a respirator by the
OSHA PEL, short-term exposure limit, or ceiling limit.
The APFs are not assumed to be interchangeable for any COU, any workplace, or any worker. The use
of a respirator would not necessarily resolve inhalation exposures if the industrial hygiene program in
place is poorly maintained. An inadequate respiratory protection program could lead to inadequate
respirator fit tests and poor maintenance of respirators which could affect APF. Based on the APFs
specifically identified for asbestos and presented in Table 5-1, inhalation exposures may be reduced by a
factor of 10 to 10,000 assuming employers institute a comprehensive respiratory protection program.
5.1.1.2 Summary of Inhalation Exposure Assessment
Table 5-2 summarizes the number of establishments and total number of exposed workers for all
occupational exposure scenarios (see Appendix E for additional information).
Table 5-2. Summary of Total Number of Workers and ONUs Potentially Exposed to Asbestos for
Each OES"
OES
Total Exposed
Workers
Total Exposed
ONUs
Total Exposed
Workers and ONUs
Number of
Establishments"
Maintenance, renovation, and
demolition
3.7E6
1.2E6
4.8E6
6.8E5
Firefighting and other disaster
response activities (career)
3.6E5
N/A
3.6E5
5.2E3
Firefighting and other disaster
response activities (volunteer)
6.8E5
N/A
6.8E5
2.4E4
Use, repair, or removal of
industrial and commercial
appliances or machinery
containing asbestos
6.4E4
5.5E4
1.2E5
2.9E4
Handling articles or
formulations that contain
asbestos (battery insulators,
burner mats, plastics, cured
coatings/adhesives/sealants)
3.1E5
1.6E5
4.7E5
1.6E4
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OES
Total Exposed
Workers
Total Exposed
ONUs
Total Exposed
Workers and ONUs
Number of
Establishments"
Waste handling, disposal, and
treatment
2.6E4
4.7E4
7.3E4
5.0E3
11 EPA's approach and methodology for estimating the number of esta
of workers and ONUs potentially exposed to asbestos can be found in
)lishments using asbestos and the number
Appendix E.
2861
2862 A summary of inhalation exposure results based on monitoring data and exposure modeling for each
2863 OES is presented for higher-exposure potential workers in Table 5-3, lower-exposure potential workers
2864 in Table 5-4, and ONUs in Table 5-5. These tables provide a summary of 8-hour time-weighted average
2865 (8-hour TWA) and short-term (30-min) inhalation exposure estimates, as well as average daily
2866 concentration (ADC) estimates based on the 8-hour TWA monitoring data. Additional details regarding
2867 occupational ADC calculations can be found in Appendix E.5.4. Also, it is important to note that EPA
2868 provides qualitative assessments of potential exposures for the Handling of vermiculite-containing
2869 products OES (Appendix E.14.2) and the Mining of non-asbestos commodities OES (Appendix E.15.2);
2870 therefore, exposures and number of workers are not quantified for the two aforementioned OESs.
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Table 5-3. Summary of Inhalation Exposure Results for Higher-Exposure Potential Workers Based on Monitoring Data and
OES
Inhalation Monitoring (Worker, f/cc)fl
Short-Term
(30-minute)
8-hr TWA
Average Daily C
(AD<
Concentrations
C)h
HE
CT
HE
CT
HE
CT
Maintenance, renovation, and demolition
0.16
2.5E-2
0.43
1.1E-3
2.0E-2
5.1E-5
Firefighting and other disaster response activities
(career)
—
—
0.39
2.0E-2
1.1E-3
5.5E-5
Firefighting and other disaster response activities
(volunteer)
—
—
0.39
2.0E-2
3.5E-4
1.8E-5
Use, repair, or removal of industrial and
commercial appliances or machinery containing
asbestos
0.17
1.9E-2
0.16
8.4E-3
3.6E-2
1.9E-3
Handling articles or formulations that contain
asbestos (battery insulators, burner mats, plastics,
cured coatings/adhesives/sealants)
8.8E-2
7.3E-2
0.69
0.10
0.16
2.3E-2
Waste handling, disposal, and treatment
—
—
3.2E-2
1.5E-3
7.2E-3
3.4E-4
11 Where there is no split between higher and lower-exposure potential workers, workers are grouped with higher-exposure potential workers and lower-
exposure potential workers are not assessed.
h ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated using the 30-minute exposure concentrations
presented here, averaged with 7.5 hours at the full shift (i.e.. 8-hour TWA) exposure concentrations. See Table_Apx E-47 for ADC estimates associated
with short-term exposures.
2873
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Table 5-4. Summary of Inhalation Exposure Results for Lower-Exposure Potential Workers Based on Monitoring Data and Exposure
OES
Inhalation Monitoring (Worker, f/cc)fl
Short-Term
(30-minute)
8-hour TWA
Average Daily
Concentrations (ADC)*
HE
CT
HE
HE
HE
CT
Maintenance, renovation, and demolition
2.5E-2
2.5E-2
0.22
1.1E-3
1.0E-2
5.1E-5
Firefighting and other disaster response activities
(career)
—
—
—
—
—
—
Firefighting and other disaster response activities
(volunteer)
—
—
—
—
—
—
Use, repair, or removal of industrial and
commercial appliances or machinery containing
asbestos
Handling articles or formulations that contain
asbestos (battery insulators, burner mats, plastics,
cured coatings/adhesives/sealants)
4.2E-2
2.1E-2
1.1E-2
8.3E-3
2.5E-3
1.9E-3
Waste handling, disposal, and treatment
—
—
—
—
—
—
11 Where there is no split between higher and lower-exposure potential workers, workers are grouped with higher-exposure potential workers and lower-
exposure potential workers are not assessed.
h ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated using the 30-minute exposure concentrations
presented here, averaged with 7.5 hours at the full shift (i.e.. 8-hour TWA) exposure concentrations. See Table_Apx E-47 for ADC estimates associated
with short-term exposures.
2876
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OES
Inhalation Monitoring (Worker, f/cc)
Short-Term
(30-minute)
8-hr TWA
Average Daily Concentrations
(ADC)"
111
CT
111
CT
111
CT
Maintenance, renovation, and demolition
5.3E-2
2.7E-2
4.6E-2
1.2E-2
2.1E-3
5.6E-4
Firefighting and other disaster response activities
(career)
-
-
-
-
-
-
Firefighting and other disaster response activities
(volunteer)
-
-
-
-
-
-
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
-
-
4.9E-2
2.8E-2
1.1E-2
6.4E-3
Handling articles or formulations that contain
asbestos (battery insulators, burner mats, plastics,
cured coatings/adhesives/sealants)
1.5E-3
7.7E-4
1.2E-3
1.1E-3
2.6E-4
2.5E-4
Waste handling, disposal, and treatment
-
-
-
-
-
-
11 ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated using the 30-minute exposure concentrations
presented here, averaged with 7.5 hours at the full shift (i.e.. 8-hour TWA) exposure concentrations. See Table_Apx E-47 for ADC estimates associated
with short-term exposures.
2878
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2879 5.1.1.3 Summary of Dermal and Oral Exposure Assessment
2880 As described in Section 5.1, dermal and oral exposures are not assessed for workers and ONUs in Part 2
2881 of the risk evaluation for asbestos.
2882
2883 5.1.1.4 Weight of Scientific Evidence Conclusions for Occupational Exposure
2884 In Table 5-6, EPA provides a summary of the weight of scientific evidence for each of the OESs
2885 indicating whether monitoring data was reasonably available, the number of data points identified, the
2886 quality of the data, EPA's overall confidence in the data, and whether the data was used to estimate
2887 inhalation exposures for workers and ONUs. Appendix E provides further details of EPA's overall
2888 confidence for inhalation exposure estimates for each OES assessed.
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2889 Table 5-6. Summary of the Weight of Scientific Evidence for Occupational Exposure Estimates by PES"
OES
Inhalation Exposure
Monitoring
Weight of Scientific
Evidence Conclusion
High Exposure-
Potential
Worker
# Data
Points
Low Exposure-
Potential
Worker
# Data
Points
ONU
# Data
Points
Data Quality
Ratings
Worker
ONU
Maintenance, renovation,
and demolition
V
992
V
36
V
104
H
Moderate
Moderate
Firefighting and other
disaster response activities
V
62
X
N/A
X
N/A
H
Moderate to
Robust
N/A
Use, repair, or removal of
industrial and commercial
appliances or machinery
containing asbestos
V
253
X
N/A
V
20
H
Moderate to
Robust
Moderate to
Robust
Handling articles or
formulations that contain
asbestos (battery insulators,
burner mats, plastics, cured
coatings/ adhesives/
sealants)
V
62
V
15
V
8
H
Moderate
Moderate
Waste handling, disposal,
and treatment
V
95
X
N/A
X
N/A
H
Moderate
N/A
11 The number of data points is the combined count of TWA and short-term samples. Where EPA was not able to estimate ONU inhalation exposure from
monitoring data or models, this was assumed equivalent to the central tendency experienced by workers for the corresponding OES; dermal exposure for
workers and ONUs was not evaluated because asbestos is not expected to absorb into the body through the skin.
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5.1.1.4.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for
the Occupational Exposure Assessment
Number of Workers
There are several uncertainties surrounding the estimated number of workers potentially exposed to
asbestos, as outlined below. Most are unlikely to result in a systematic underestimate or overestimate but
could result in an inaccurate estimate.
There are also uncertainties with BLS data, which are used to estimate the number of workers for the
remaining conditions of use. First, BLS employment data for each industry/occupation combination are
only available at the 3-, 4-, or 5-digit NAICS level, rather than the full 6-digit NAICS level. This lack of
granularity could result in an overestimate of the number of exposed workers if some 6-digit NAICS are
included in the less granular BLS estimates but are not, in reality, likely to use asbestos for the assessed
applications. EPA addressed this issue by refining the OES estimates using total employment data from
the U.S. Census Statistics of U.S. Businesses (SUSB). However, this approach assumes that the
distribution of occupation types (SOC codes) in each 6-digit NAICS is equal to the distribution of
occupation types at the parent 5-digit NAICS level. If the distribution of workers in occupations with
asbestos exposure differs from the overall distribution of workers in each NAICS, then this approach
will result in inaccuracy.
Second, EPA's judgments about which industries (represented by NAICS codes) and occupations
(represented by SOC codes) are associated with the uses assessed in this report are based on EPA's
understanding of how asbestos is used in each industry. Designations of which industries and
occupations have potential exposures is nevertheless subjective, and some industries/occupations with
few exposures might erroneously be included, or some industries/occupations with exposures might
erroneously be excluded. This would result in inaccuracy but would be unlikely to systematically either
overestimate or underestimate the number of exposed workers.
Due to limited information found in the BLS data, the number of workers and establishments for
firefighting and other disaster response activities were estimated using data from the National Fire
Protection Association (NFPA) (NFPA. 2022b). These data are based on two surveys conducted by the
NFPA and may result in some inaccuracy in the number of exposed workers estimates for this OES.
Analysis of Exposure Monitoring Data
This report uses existing worker exposure monitoring data to assess exposure to asbestos from several
conditions of use. To analyze the exposure data, EPA categorized each data point as either "worker" or
"occupational non-user," with additional designations of "higher exposure-potential" or "lower
exposure-potential" for workers. The categorizations are based on descriptions of worker job activity as
provided in literature and EPA's judgment. In general, samples for employees that are expected to have
the highest exposure from direct handling of asbestos are categorized as "worker" and samples for
employees that are expected to have the lower exposure and do not directly handle asbestos are
categorized as "occupational non-user." The occupational exposure scenario for firefighting and disaster
response also categorizes career and volunteer firefighters separately due to an expected difference in
exposure frequency.
Exposures for occupational non-users can vary substantially. Most data sources do not sufficiently
describe the proximity of these employees to the asbestos exposure source. As such, exposure levels for
the "occupational non-user" category will have high variability depending on the specific work activity
performed. It is possible that some employees categorized as "occupational non-user" have exposures
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similar to those in the "worker" category depending on their specific work activity pattern. There were
two OESs {i.e., Maintenance, renovation, and demolition; and Use, repair, or removal of industrial and
commercial appliances or machinery containing asbestos) where ONU central tendency exposure values
were estimated at higher levels than worker central tendency exposure values. The resulting high central
tendency values for ONUs are a result of the lack of data, specifically a lack of ONU samples that
contain low measured amounts of asbestos. For the same OESs, there were more comprehensive data
available to characterize a wider range of potential worker exposure values which led to lower central
tendency exposure estimations for workers in these cases.
Also, some data sources may be inherently biased. For example, bias may be present if exposure
monitoring was conducted to address concerns regarding adverse human health effects reported
following exposures during use or if exposure monitoring results were only provided from industry.
Another source of bias among data, commonly known as the "Hawthorne effect," occurs due to changes
in behavior of the individual being monitored. Specifically, workers that are aware that they are being
monitored may exhibit more hygienic practices if they wish to show that there is lesser exposure in their
occupation, or they may exhibit less hygienic practices if they wish to show that there is greater
exposure in their occupation.
One limitation of the monitoring data is the uncertainty in the representativeness of the data. Differences
in work practices and engineering controls across sites can introduce variability and limit the
representativeness of monitoring data. The age of the monitoring data can also introduce uncertainty due
to differences in workplace practices and equipment used at the time the monitoring data were collected
compared to those currently in use. Therefore, older data may overestimate or underestimate exposures,
depending on these differences. The effects of these uncertainties on the occupational exposure
assessment are unknown, as the uncertainties may result in either overestimation or underestimation of
exposures depending on the actual distribution of asbestos air concentrations and the variability of work
practices among different sites.
Where sufficient data were reasonably available, the 95th and 50th percentile exposure concentrations
were calculated using reasonably available data. The 95th percentile exposure concentration is intended
to represent a high-end exposure level, while the 50th percentile exposure concentration represents a
central tendency exposure level. The underlying distribution of the data, and the representativeness of
the reasonably available data, are not known. Where discrete data was not reasonably available, EPA
used reported statistics (i.e., median, mean, 90th percentile, etc.). Because EPA could not verify these
values, there is an added level of uncertainty.
EPA calculated ADC values assuming workers and ONUs are regularly exposed during their entire
working lifetime, which likely results in an overestimate for some but not all. Individuals may change
jobs during the course of their career such that they are no longer exposed to asbestos, and that actual
ADC values become lower than the estimates presented.
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5.1.2 Take-Home Exposures
Monitoring data to obtain take-home exposure concentrations was described in Section 3.1.2 and in
Section 5.1.1. Briefly, the 8-hour TWA occupational exposure concentrations in Table 5-3 were used to
estimate take-home exposure concentrations from people that bring asbestos contaminated clothing from
occupational activities into their households and come to be exposed to asbestos from handling the
contaminated garments. Each of the occupational exposure scenarios discussed in Section 5.1.1 result in
distinct occupational 8-hour TWA concentrations for distinct numbers of days per year (see Table Apx
E-47), amounting to different numbers of exposure for the associated take-home scenarios from worn
occupational garments. The take-home exposure scenarios include both handlers and bystanders for each
of the OESs in Section 5.1.1:
• Maintenance, renovation, and demolition;
• Firefighting and other disaster response activities (career);
• Firefighting and other disaster response activities (volunteer);
• Use, repair, or removal of industrial and commercial appliances or machinery containing
asbestos;
• Handling articles or formulations that contain asbestos (battery insulators, burner mats, plastics,
cured coatings/adhesives/sealants); and
• Waste handling, disposal, and treatment.
The data needed to estimate the yearly average concentration for each scenario using the unit exposure
approach is summarized in Table 5-7 and are explained in Equation Apx J-l.
The unit approach described in Section 3.1.4 allows to treat different wear and wash patterns similarly if
they will yield equal yearly average concentrations. This approach greatly simplifies the estimation of
exposure for each take-home scenario. For example, for the wear/wash patterns discussed in Section
3.1.4 and assuming an occupational TWA concentration of 1 f/cc: (1) a worker wearing one garment set
for three consecutive days and then laundering, and (2) a worker wearing a different garment set each
day and laundering all three together both correspond to three exposure units and, when averaged over a
year, give the same yearly average concentrations. Implicit in this assumption is that all the asbestos
fibers that load onto one garment set worn over multiple workdays between washing events are retained
until the laundry preparation activity; in actuality, as a garment set is worn multiple days, some fibers
will slough off the garment, resulting in less than three full units of exposure. In the developed approach,
the key assumption used in this analysis tends to overestimate the take-home exposures for wear/wash
patterns where a single garment is worn multiple days before washing.
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Table 5-7. Data Needs to O
)tain Take-Home Yearly Average Concentrations
Variable
Value/Calculation
Source
8-hour TWA
Occupational Exposure
Concentration
[X] f/cc
Occupational exposure analysis,
Table ApxE-47
24-hour TWA Take-
Home Exposure
Concentration
Take-home slope factor" x [X] f/cc
Calculated using regression
based on available data sources,
Section 3.1.4
Frequency
[Y] days a year
Occupational exposure analysis,
Table ApxE-47
11 The [X] 8-hour TWA occupational exposure concentration and the [Y] frequency in days per year are taken
directly from the occupational exposure analysis in Table Apx E-47.
5.1.2.1 Concentrations of Asbestos in Take-Home Scenarios
The 24-hour TWA take-home concentrations are estimated using the 8-hour TWA loading
concentrations, CT for central tendency and HE for high-end tendency and the take-home slope factors
(CT and HE). CT and HE were obtained from the reported average and maximum for each study, four
studies and six data points were used to obtain CT and three studies were used for HE (see Section
3.1.2). In this calculation, the CT slope factor is multiplied by the CT loading concentration to estimate
the CT take-home concentration, and similarly for the HE estimates. The take-home concentrations are
estimated using the "higher-exposure potential worker" from Table 5-3. Then the yearly average
concentration for lifetime cancer risk is calculated using Equation 5-1.
Equation 5-1. Yearly Average Take-Home Concentration Example Calculation Using
Equation Apx J-l
Yearly Ave Concen = [X f/cc] x take-home slope factor x
Yearly Ave Concen = 1.10 x 10~3f/cc x 0.0011 x
[Y days]
.365 days.
[5 0 days]
.365 days.
Yearly Ave Concen Handler CT = 1.67 x 10~7f/cc
Calculations and slope factor approaches to obtain take-home exposure concentrations and the lifetime
and non-cancer chronic risk values estimates are available in Asbestos Part 2 Draft RE - Risk Calculator
for Take Home - Fall 2023 (see Appendix C).
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3035 Table 5-8. Estimated CT and HE Yearly Average Concentrations Using Take-Home Slope Factors
OES, Higher-Exposed Worker
8-hr TWA Loading
Concentration (f/cc)
Yearly Average Take Home Concentration (f/cc)
CT
HE
Handler
Bystander
CT
HE
CT
HE
Maintenance, renovation, and demolition
1.10E-3
4.30E-1
1.66E-7
5.77E-4
1.06E-7
3.79E-4
Firefighting and other disaster response
activities (career)
2.00E-2
3.90E-1
1.81E-7
3.14E-5
1.15E-7
2.06E-5
Firefighting and other disaster response
activities (volunteer)
2.00E-2
3.90E-1
6.03E-8
1.05E-5
3.84E-8
6.87E-6
Use, repair, or removal of industrial and
commercial appliances or machinery
containing asbestos
8.40E-3
1.60E-1
6.33E-6
1.07E-3
4.03E-6
7.05E-4
Handling articles or formulations that
contain asbestos (battery insulators,
burner mats, plastics, cured
coatings/adhesives/sealants)
1.00E-1
6.90E-1
7.54E-5
4.63E-3
4.80E-5
3.04E-3
Waste handling, disposal, and treatment
1.50E-3
3.20E-2
1.13E-6
2.15E-4
7.20E-7
1.41E-4
Notes:
CT Slope Factor for Handler is 0.0011 and for Bystander is 0.00070.
CT SIodc Factor was obtained usins regression 3 usins Madl et al. (2008). Jians et al. (2008). Salunel et al. (2014). and Salunel
etal. (2016).
HE Slope Factor for Handler is 0.0098 and for Bystander is 0.0064.
HE Slope Factor was obtained usinp repression 2 usins Abelmann et al. (2017). Madl et al. (2014). and Madl et al. (2009).
3036 5.1.2.2 Weight of Scientific Evidence Conclusions for Take-Home
3037 Overall confidence in each take-home scenario is robust (+++) for maintenance and renovation, and
3038 moderate to robust (++ to +++) for all other OESs. The slight confidence in the data used for four of the
3039 OESs is because EPA used the regression of the two OESs with data to calculate concentration of
3040 asbestos fibers in one garment and extrapolated the use of these data to the other four OESs. The
3041 regression approach and the use of occupational setting concentrations is of robust and moderate
3042 confidence for the scenarios in which the regression was built and the scenarios for which the regression
3043 was extrapolated.
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Table 5-9. Weight of Scientific Evidence Conclusions for Take-Home Exposure Scenarios
Take-Home Scenario/OES
Confidence
in Data
Used
Confidence in User-Selected Varied Inputs
Weight of
Scientific
Evidence
Conclusion
Regression
Slope
Approach
8-hour
TWA Occ.
Loading
24-hour
TWA Take-
Home
Loading
Frequency
(Y)
Maintenance, renovation,
and demolition handler and
bystander
++
+++
++
+++
+++
+++
Firefighting and other
disaster response activities
(career) handler and
bystander
+
++
++
++
+++
++ to +++
Firefighting and other
disaster response activities
(volunteer) handler and
bystander
+
++
++
++
+++
++ to +++
Use, repair, or removal of
industrial and commercial
appliances or machinery
containing asbestos handler
and bystander
+
++
++
++
+++
++ to +++
Handling articles or
formulations that contain
asbestos (battery insulators,
burner mats, plastics, cured
coatings/adhesives/sealants)
handler and bystander
++
++
++
++
+++
++ to +++
Waste handling, disposal,
and treatment handler and
bystander
+
++
++
++
+++
++ to +++
+ = Slight; ++ = moderate; +++ = robust
5.1.2.2.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for
the Take-Home Exposure Assessment
Variability and uncertainty in the take-home exposure approaches, calculations, assumptions, and
concentrations calculated are both addressed in this section. Variability refers to the inherent
heterogeneity or diversity of data in an assessment. It is a description of the range or spread of a set of
values. Uncertainty refers to a lack of data or an incomplete understanding of the context of the risk
evaluation decision.
Variability cannot be reduced, but it can be better characterized. Uncertainty can be reduced by
collecting more or better data. Uncertainty is addressed qualitatively by including a discussion of factors
such as data gaps and subjective decisions or instances where professional judgment was used.
Uncertainties associated with approaches and data used in the evaluation of take-home exposures are
described below.
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Table 5-10. Qualitative Assessment of the Uncertainty and Variability Associated with
Concentrations Data Used in Take-Home Exposure Ana
ysis
Variable Name
Effect
Data
Source
Uncertainty
(Low, Medium,
High)
Variability
(Low, Medium, High)
Overall take-home
24-hour
concentration data
Take-home regression
approach includes a number
of activity-based asbestos
releases, more studies would
help keep the uncertainty at
low.
Section
3.1.2
Low, number of
studies and overall
rating
High, data ranges 3 to 4
orders of magnitude
Overall take-home
yearly
concentration
calculation
More studies are expected to
decrease the uncertainty.
Section
5.1.2
Medium, CT and HE
approaches for
specific activities not
available extrapolated
for COUs that did not
have specific activity
data.
High, data ranges 3 to 4
orders of magnitude
Occupational
parameters used in
yearly
concentrations
Section
5.1.2
Low, occupational
parameters are well
understood and
characterized
NA
Overall take-
home
concentration
data
Concentrations used in risk
calculation estimates
Section
3.1.2 and
5.1.2
Low, number of
studies,
representative of
take-home scenarios
with well
understood use
parameters
High, data ranges 3 to 4
orders of magnitude
Variability refers to the inherent heterogeneity or diversity of data in an assessment, while uncertainty refers to a lack of
data or an incomplete understanding of the context of the risk evaluation decision.
5.1.3 Consumer Exposures
5.1.3.1 Approach and Methodology
Part 2 of the risk evaluation covers exposure to consumer legacy uses and associated disposals of all
forms of asbestos, as well as consideration of talc and vermiculite products that may contain asbestos.
5.1.3.1.1 Consumer COUs and Activity-Based Exposure
Table 3-5 and Table 3-6 summarize the consumer COUs, activity-based scenarios that are quantitatively
evaluated. Direct inhalation of particulate/dust containing asbestos fibers from activity-based scenarios
is expected to be the most significant route of exposure to released friable asbestos fibers for DIY
consumers and bystanders, see Section 5.1 for a detailed discussion of evaluated exposure routes.
5.1.3.1.2 Consumer Exposure and Risk Estimation Approach
Consumer and bystander activity-based exposure concentrations and risks were calculated using
Equation Apx H-l, which is the general equation for estimating cancer risks for lifetime and less than
lifetime exposure from inhalation of asbestos, from the Office of Land and Emergency Management
Framework for Investigating Asbestos-contaminated Saperfand Sites (U.S. EPA. 2008).
All of the activity-based scenarios considered people 16 years of age and older of all genders for DIY
users and, and all ages and genders for bystanders. The exposure duration is 62 years for DIY users and
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78 years for bystanders, and the averaging time is 78 years. The TWFs accounting for lifetime cancer
exposure time and frequency are summarized in Table 5-11. The non-cancer chronic TWF are calculated
using Equation Apx H-3 and the values are summarized in Table 5-13, while all basis for assumptions
and descriptions remain the same for lifetime and chronic. The values are based on assumptions related
to the activity type (e.g., disturbance/repair or removal) rather than the specific product.
For repair activities, it was assumed that a DIY user may perform one repair or renovation task where
they may disturb ACM per year, and the length of time spent on the task varies for low-end, high-end,
and central tendency exposure estimates. These time estimates are based on reasonably available
information, including EPA guidance documents (Exposure Factors Handbook (U.S. EPA. 2011)) and
professional judgement of EPA staff. For removal activities, EPA reviewed the frequency of
replacement for various home materials such as tiles and roofing, but also considered the likelihood of
consumers encountering legacy use ACM. For example, while industry experts might recommend
replacing floor tile every 20 years, only the first replacement job is likely to involve removing asbestos-
containing floor tile. It is unlikely that newly installed floor tile that might be replaced again after 20
years would contain asbestos. Therefore, it was assumed for low-end and central tendency estimates, a
DIY user perform removal jobs with asbestos-containing products once in their lifetime, and for high-
end estimates, a DIY user might remove asbestos-containing products three times over their lifetime. It
was assumed that each removal job takes 10 days for central tendency and high-end and estimates and 5
days for low-end estimates. In contrast to repair activities, it was assumed that removal work takes a
longer time (i.e., 8 hours per day). Lifetime cancer and non-cancer chronic risk estimates are available in
Asbestos Part 2 Draft RE - Risk Calculator for Consumer - Fall 2023 (see Appendix C).
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Table 5-11. Lifetime Cancer Time-Weighting Factors Assumptions for All CPUs
Activity-Based Scenario
Low- End
TWF
Low-End TWF Basis
High-End
TWF
High-End TWF Basis
Central
Tendency TWF
Central-Tendency TWF
Basis
Construction, paint, electrical, and metal products COU: construction and building materials covering large surface areas subcategory
Outdoor, disturbance/repair
(sanding or scraping) of
roofing materials
0.00006
Assumed 1 repair/year,
taking 1 day, lasting 30
min/day
0.00034
Assumed 1 repair/year,
taking 1 day, lasting 3
lir/day
0.00011
Assumed 1 repair/year,
taking 1 day, lasting 1
lir/day
Outdoor, removal of roofing
materials
0.00457
Assumed 1 removal job in
lifetime taking 5 days
lasting 8 lir/day
0.02740
Assumed 3 removal jobs in
lifetime taking 10 days
lasting 8 lir/day
0.00913
Assumed 1 removal job in
lifetime taking 10 days
lasting 8 lir/day
Indoor, removal of plaster
0.00457
Assumed 1 removal job in
lifetime taking 5 days
lasting 8 lir/day
0.02740
Assumed 3 removal jobs in
lifetime taking 10 days
lasting 8 lir/day
0.00913
Assumed 1 removal job in
lifetime taking 10 days
lasting 8 lir/day
Indoor, disturbance (sliding) of
ceiling tiles
0.00006
Assumed 1 repair/year,
taking 1 day, lasting 30
min/day
0.00034
Assumed 1 repair/year,
taking 1 day, lasting 3
lir/day
0.00011
Assumed 1 repair/year,
taking 1 day, lasting 1
lir/day
Indoor, removal of ceiling tiles
0.00457
Assumed 1 removal job in
lifetime taking 5 days
lasting 8 lir/day
0.02740
Assumed 3 removal jobs in
lifetime taking 10 days
lasting 8 lir/day
0.00913
Assumed 1 removal job in
lifetime taking 10 days
lasting 8 lir/day
Indoor, maintenance (chemical
stripping, polishing, or buffing)
of vinyl floor tiles
0.00006
Assumed 1 repair/year,
taking 1 day, lasting 30
min/day
0.00034
Assumed 1 repair/year,
taking 1 day, lasting 3
lir/day
0.00011
Assumed 1 repair/year,
taking 1 day, lasting 1
lir/day
Indoor, removal of vinyl floor
tiles
0.00457
Assumed 1 removal job in
lifetime taking 5 days
lasting 8 lir/day
0.02740
Assumed 3 removal jobs in
lifetime taking 10 days
lasting 8 lir/day
0.00913
Assumed 1 removal job in
lifetime taking 10 days
lasting 8 lir/day
Indoor, disturbance/repair
(cutting) of attic insulation.
0.00006
Assumed 1 repair/year,
taking 1 day, lasting 30
min/day
0.00034
Assumed 1 repair/year,
taking 1 day, lasting 3
lir/day
0.00011
Assumed 1 repair/year,
taking 1 day, lasting 1
lir/day
Construction, paint, electrical, and metal products COU: fillers and putties subcategory
Indoor, disturbance (pole or
hand sanding and cleaning) of
spackle
0.00006
Assumed 1 repair/year,
taking 1 day, lasting 30
min/day
0.00034
Assumed 1 repair/year,
taking 1 day, lasting 3
lir/day
0.00011
Assumed 1 repair/year,
taking 1 day, lasting 1
lir/day
Indoor, disturbance (sanding
and cleaning) of coatings,
mastics, and adhesives
0.00006
Assumed 1 repair/year,
taking 1 day, lasting 30
min/day
0.00034
Assumed 1 repair/year,
taking 1 day, lasting 3
lir/day
0.00011
Assumed 1 repair/year,
taking 1 day, lasting 1
lir/day
Indoor, removal of floor
tile/mastic
0.00457
Assumed 1 removal job in
lifetime taking 5 days
lasting 8 lir/day
0.02740
Assumed 3 removal jobs in
lifetime taking 10 days
lasting 8 lir/day
0.00913
Assumed 1 removal job in
lifetime taking 10 days
lasting 8 lir/day
Indoor, removal of window
caulking
0.00457
Assumed 1 removal job in
lifetime taking 5 days
lasting 8 lir/day
0.02740
Assumed 3 removal jobs in
lifetime taking 10 days
lasting 8 lir/day
0.00913
Assumed 1 removal job in
lifetime taking 10 days
lasting 8 lir/day
Furnishing, cleaning, treatment care products COU: construction and building materials covering large surface areas, including fabrics, textiles, and apparel subcategory
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Activity-Based Scenario
Low- End
TWF
Low-End TWF Basis
High-End
TWF
High-End TWF Basis
Central
Tendency TWF
Central-Tendency TWF
Basis
Use of mittens for glass
manufacturing, (proxy for
oven mittens and potholders)
0.00019
Assumed BBQ1 mittens
used more than other
hobbies. People grill on
average 1 lir/day, 1 day per
week (52 days per year),
using an ACM mitt for 2
years over their lifetime
0.00096
Assumed BBQ mittens used
more than other hobbies.
People grill on average 1
lir/day, 1 day per week (52
days per year), using an
ACM mitt for 10 years over
their lifetime
0.00048
Assumed BBQ mittens used
more than other hobbies.
People grill on average 1
lir/day, 1 day per week (52
days per year), using an
ACM mitt for 5 years over
their lifetime
Note, EPA assumed a cooking or grilling activity-based scenario, which is likely performed in higher frequencies and durations than other hobbies requiring the need for
protective clothing such as mittens and potholders under this COU.
3101
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5.1.3.2 Summary of Consumer Activity-Based Scenarios Exposure Concentrations
Using Equation Apx H-l in Appendix H.2 the exposure point concentrations summarized in Table 3-6
and TWFs summarized in Table 5-11, exposure concentrations were calculated for each activity-based
scenario and are presented in Table 5-12 and Table 5-13 for lifetime cancer and non-cancer chronic.
Table 5-12. Lifetime Cancer Human Exposure Concentrations for Consumer Exposure Activity-
Activity-Based Scenario
Lifetime Cancer Human Exi
)osure Concentration (f/cc)
DIY User (62-year exposure)
Bystander (lifetime exposure)
Low-End
Central
Tendency
High-End
Low-
End
Central
Tendency
High-End
Construction, paint, electrical, and metal products COU: construction and building materials covering large surface areas
subcategory
Outdoor, disturbance/repair (sanding or
scraping) of roofing materials
2.5E-7
7.9E-7
3.3E-6
4.2E-8
1.3E-7
5.5E-7
Outdoor, removal of roofing materials
2.3E-5
4.6E-5
2.7E-4
2.3E-5
4.6E-5
2.7E-I
Indoor, removal of plaster
4.6E-5
1.8E-4
1.4E-3
2.3E-5
4.6E-5
2.7E-I
Indoor, disturbance (sliding) of ceiling
tiles
1.3E-6
2.6E-6
1.5E-5
1.3E-6
2.6E-6
1.5E-5
Indoor, removal of ceiling tiles
2.3E-5
8.2E-5
5.2E-4
3.8E-6
1.4E-5
8.7E-5
Indoor, maintenance (chemical
stripping, polishing, or buffing) of vinyl
floor tiles
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Indoor, removal of vinyl floor tiles
2.6E-5
5.1E-5
1.5E-4
1.8E-6
3.7E-6
1.1E-5
Indoor, disturbance/repair (cutting) of
attic insulation
6.6E-5
1.3E-4
4.0E-4
2.8E-5
5.6E-5
1.7E-I
Indoor, moving and removal with
vacuum of attic insulation
4.4E-3
4.7E-2
2.5E-1
2.1E-3
9.1E-3
4.2E-2
Construction, paint, electrical, and metal products COU: fillers and putties subcategory
Indoor, disturbance (pole or hand
sanding and cleaning) of spackle
7.1E-5
1.6E-3
8.9E-3
1.1E—4
5.7E-4
3.3E-3
Indoor, disturbance (sanding and
cleaning) of coatings, mastics, and
adhesives
1.3E-6
2.6E-6
1.4E-5
1.7E-7
3.4E-7
2.7E-6
Indoor, removal of floor tile/mastic
2.3E-5
4.6E-5
2.7E-4
2.3E-5
4.6E-5
2.7E-I
Indoor, removal of window caulking
2.3E-5
4.6E-5
2.7E-4
2.3E-5
4.6E-5
2.7E-I
Furnishing, cleaning, treatment care products COU: Construction and building materials covering large surface areas,
including fabrics, textiles, and apparel Subcategory
Use of mittens for glass manufacturing,
(oven mittens and potholders)
2.3E-5
1.4E-4
5.1E-4
3.8E-6
2.3E-5
8.5E-5
3109
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Table 5-13. Non-cancer Chronic Human Exposure Concentrations for Consumer Exposure
Activity-Based Scenarios by CPU and Subcategory
Activity-Based Scenario
Non-cancer Chronic Human Exposure Concentration (f/cc)
DIY User (62-year exposure)
Bystander (lifetime exposure)
Low-End
Central
Tendency
High-End
Low-
End
Central
Tendency
High-End
Construction, paint, electrical, and metal products COU: construction and building materials covering large surface areas
subcategory
Outdoor, disturbance/repair (sanding or
scraping) of roofing materials
2.0E-7
6.3E-7
2.6E-6
3.4E-8
1.0E-7
4.4E-7
Outdoor, removal of roofing materials
1.8E-5
3.6E-5
2.2E-4
1.8E-5
3.6E-5
2.2E-1
Indoor, removal of plaster
3.6E-5
1.5E-4
1.1E-3
1.8E-5
3.6E-5
2.2E-1
Indoor, disturbance (sliding) of ceiling
tiles
1.0E-6
2.0E-6
1.2E-5
1.0E-6
2.0E-6
1.2E-5
Indoor, removal of ceiling tiles
1.8E-5
6.5E-5
4.1E-4
3.0E-6
1.1E-5
6.9E-5
Indoor, maintenance (chemical
stripping, polishing, or buffing) of vinyl
floor tiles
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Indoor, removal of vinyl floor tiles
2.0E-5
4.1E-5
1.2E-4
1.5E-6
2.9E-6
8.7E-6
Indoor, disturbance/repair (cutting) of
attic insulation.
5.3E-5
1.1E-4
3.2E-4
2.2E-5
4.5E-5
1.3E-1
Indoor, moving and removal with
vacuum of attic insulation
3.5E-3
3.7E-2
2.0E-1
1.7E-3
7.3E-3
3.4E-2
Construction, paint, electrical, and metal products COU: fillers and putties subcategory
Indoor, disturbance (pole or hand
sanding and cleaning) of spackle
5.7E-5
1.3E-3
7.0E-3
8.8E-5
4.5E-4
2.6E-3
Indoor, disturbance (sanding and
cleaning) of coatings, mastics, and
adhesives
1.0E-6
2.1E-6
1.1E-5
1.4E-7
2.7E-7
2.2E-6
Indoor, removal of floor tile/mastic
1.8E-5
3.6E-5
2.2E-4
1.8E-5
3.6E-5
2.2E-1
Indoor, removal of window caulking
1.8E-5
3.6E-5
2.2E-4
1.8E-5
3.6E-5
2.2E-1
Furnishing, cleaning, treatment care products COU: construction and building materials covering large surface areas,
including fabrics, textiles, and apparel subcategory
Use of mittens for glass manufacturing,
(oven mittens and potholders)
1.8E-5
1.1E-4
4.0E-4
3.0E-6
1.8E-5
6.7E-5
5.1.3.3 Weight of Scientific Evidence Conclusions for Consumer Exposure
There is uncertainty associated with the activity-based scenarios' TWF assumptions summarized in
Section 5.1.3.1.2. EPA considered using the Exposure Factors Handbook suggestions for general
activities when it seemed relevant. However, many of the activity scenarios built in this evaluation are
specific and unique to the hazard and asbestos COU, and the Exposure Factors Handbook did not
contain appropriate time or frequency information. Table 16-100 "Annual Average Time Use by the
U.S. Civilian Population, Ages 15 Years and Older" provides an annual average time estimate of 1.79
hours spent on household activities, which includes home maintenance, repair, and renovation. This
seemed to underestimate time spent performing specific DIY user activities, so EPA used professional
judgement to develop exposure time and frequency estimates for repair/disturbance and removal
activities, see Table 5-11.
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As noted in the prior section, EPA used occupational studies as proxies for DIY consumer scenarios.
There is uncertainty related to differences in exposure patterns between professionals and DIY users.
For example, DIY work is expected to be on a smaller scale than professional work, but due to lack of
experience or proper tools DIY users may take longer to perform certain tasks.
For bystanders, it is a conservative assumption that bystanders are present during every instance a DIY
user performs work disturbing asbestos-containing products, and that bystanders remain within the work
area of the DIY user throughout the entire time the DIY user is performing the work. Bystander
exposures therefore may be overestimated, but the magnitude is uncertain.
Finally, EPA has made assumptions regarding both age at start of exposure and duration of exposure for
DIY users and bystanders that may overestimate exposures.
Table 5-14. Weight of Scientific Evidence Conclusions for Consumer Exposure Activity-Based
Scenarios
Activity-Based DIY
Scenario
DIYer/
Bystander
Confidence
in Data Used
Confidence in User-Selected Varied
Inputs
Weight of
Scientific
Evidence
Conclusion
EPC
TWF
ED
AT
Outdoor,
disturbance/repair
(sanding or scraping) of
roofing materials
DIYer
++
++
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Outdoor, removal of
roofing materials
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, removal of
plaster
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, disturbance
(sliding) of ceiling tiles
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, removal of
ceiling tiles
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, maintenance
(chemical stripping,
polishing, or buffing) of
vinyl floor tiles
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, removal of
vinyl floor tiles
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, disturbance /
repair (cutting) of attic
insulation
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, moving and
removal (with vacuum)
of attic insulation
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
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Activity-Based DIY
Scenario
DIYer/
Bystander
Confidence
in Data Used
Confidence in User-Selected Varied
Inputs
Weight of
Scientific
Evidence
Conclusion
EPC
TWF
ED
AT
Indoor, disturbance
(pole or hand sanding
and cleaning) of
spackle
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, disturbance
(sanding and cleaning)
of coatings, mastics,
and adhesives
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, removal of
floor tile/mastic
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Indoor, removal of
window caulking
DIYer
++
++ to +
++
+++
+++
++
Bystander
+
+
++
+++
+++
+ to ++
Use of mittens for glass
manufacturing, (proxy
for oven mittens and
potholders)
DIYer
++
+
+
+++
+++
+ to ++
Bystander
+
+
+
+++
+++
+ to ++
3140
3141 5.1.3.3.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for
3142 the Consumer Exposure Assessment
3143 Variability and uncertainty in the consumer DIY activity-based exposure approaches, assumptions and
3144 concentrations calculated are both addressed in this section. Variability refers to the inherent
3145 heterogeneity or diversity of data in an assessment. It is a description of the range or spread of a set of
3146 values and cannot be reduced, but it can be better characterized. Uncertainty refers to a lack of data or an
3147 incomplete understanding of the context of the risk evaluation decision. Uncertainty is addressed
3148 qualitatively by including a discussion of factors such as data gaps and subjective decisions or instances
3149 where professional judgment was used.
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Table 5-15. Qualitative Assessment of the Uncertainty and Variability Associated with Consumer
iisk Assessment
Variable Name
Effect
Data Source
Uncertainty
(+, ++, +++)a
Variability
(+, ++, +++) "
Overall consumer DIY
concentration data
Concentrations used in risk calculation
estimates (EPC).
Systematic review identified
studies measurements
++
++b
Exposure time (activity
time in hours during a
day) within a TWF d
calculation
Assumption used in all scenarios that only
one activity is performed. This assumption
may underestimate risk d
Assumption
+c
+++
Exposure duration (years
of exposure) within TWF
calculation
Assumption for each activity type used in
the calculation of LE, CT, and HE exposure
concentrations
Assumption
+++
+++
Exposure duration
Assumption for all consumer DIY scenarios
to start at 16 years of age covers most
practical and usual exposures in a lifetime
Assumption
+++
+++
Overall consumer DIY
concentration data
Overall calculation of human exposure
concentration
Systematic review identified
studies measurements,
assumptions, and other
parameters
++ to +++
++6
11 + = slight; ++ = moderate; +++ = robust.
h Low-end to high-end concentration ranges were within the same or one order of magnitude difference for all scenarios concentrations.
c It is possible that similar activities can be performed more than once in a lifetime.
d Time-weighting factors (TWF) values are based on assumptions, where similar job types (e.g., "repair") were given consistent TWF. The assumptions take
into account not only the frequency of a job type (e.g., "roof replacement") but also the number of times per lifetime that a given job will include asbestos
materials. For example, a roof may be replaced every 10 years, but only the first replacement job is likely to include legacy use asbestos; in contrast, repeat
repair jobs are more likely to contain legacy asbestos each time.
3151
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5.1.4 General Population Exposures
General population exposures occur when asbestos fibers are released into the environment from
occupational activities and people that live or recreate at certain distances (10, 30, 60, 100, 1,000, 2,500,
5,000, and 10,000 m) from the release source are exposed from inhaling suspended fibers. Section 3.3
provides a summary of the monitoring, database, and modeled data concentrations of asbestos fibers
released into the environment from occupational activities.
5.1.4.1 Approach and Methodology
Asbestos fibers have been detected in the outdoor environment indicating that some amount of exposure
is occurring and vary across the general population depending on proximity to sources and the activities
releasing asbestos fibers. See Section 3.3.3 for a summary of environmental studies where asbestos has
been measured and detected in various environmental media.
Emission of asbestos fibers is expected to occur through the following mechanisms: releases from
activities in which asbestos materials are modified, and abrasion of materials to form small particulates
through routine use. Releases of asbestos fibers to the outdoor environment may occur through direct
releases to air as well as indirect releases from the indoor environment activities. In this analysis, EPA
does not aggregate the activities that modified asbestos containing materials in indoor environments, like
those from occupational exposures, in Section 5.1.1, and DIY consumer exposures in Section 5.1.3 to
the environmental releases concentrations infiltrating the indoor environment. In this analysis, EPA only
estimates risks from exposures to releases to the environment that then infiltrate the indoor environment.
Exposure to the general population was estimated for the industrial and commercial releases per OES
and matched to each COU. Table 5-16 summarizes industrial and commercial releases to the
environmental media by OES and COU.
Table 5-16. Summary of Environmental Releases from Industrial and Commercial Activities for
Inhalation Exposures by OES and Media
OES
COU(s)
Specific
Facility
Fugitive
Air
Generic
Facility
Fugitive
Air
Measured
Handling articles or
formulations that
contain asbestos
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
COU: Packaging, paper, plastic, toys, hobby
products
Handling asbestos-
containing building
materials during
maintenance,
renovation, and
demolition activities
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
Use, repair, or disposal
of industrial and
commercial appliances
or machinery
containing asbestos
COU: Construction, paint, electrical, and metal
products
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OES
COU(s)
Specific
Facility
Fugitive
Air
Generic
Facility
Fugitive
Air
Measured
Waste handling,
disposal, and treatment
fugitive annual ambient
air risk
COU: Disposal, including distribution for disposal
Handling asbestos-
containing building
materials during
firefighting or other
disaster response
activities
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
N/A
COU: Chemical substances in automotive, fuel,
agriculture, outdoor use products
3179
3180 Figure 5-2 depicts the methods EPA used to estimate general population inhalation exposures. The
3181 assessment used environmental release estimates that were related to the industrial and commercial OES
3182 (Section 3.2.1). Release estimates were used to model ambient air concentrations (Section 3.3.1.3). EPA
3183 modeled estimates for ambient air concentrations from environmental releases from industrial and
3184 commercial activities were used to obtain estimated inhalation exposure for the general population.
3185
Inhalation Risk Assessment
3187 Figure 5-2. Exposure Assessment Approaches Used to Estimate General Population Exposure to
3188 Asbestos
3189
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3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
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Modeled air concentrations were utilized to estimate general population risk associated to inhalation
exposures at various distances from a facility performing specific activities that release asbestos fibers,
see Section 3.3.1.3 for Specific and Generic Facilities emission concentrations grouped and summarized
by OES. Measured air concentrations in Table 3-9 are the environmental media monitoring data that was
available in the United States. For a description of statistical methods, methodology of data integration
and treatment of non-detects and outliers used to generate these estimates please reference Section
3.3.1.1 and Appendix E.17. The measured concentrations scenarios are commonly used to ground truth
portions of the results from the ambient air modeled scenarios for specific and generic facilities when
describing similar distances from the source. However, because of the differences in activity-based
scenarios asbestos fibers releases within each COU and its matching OES measured and modeled results
comparisons in this RE are to be used as a guidance rather than ground truth. See Section 3.3.1.3 for a
comparison discussion between modeled and measured concentrations for various COUs.
Concentrations in Table 3-11 are used to calculate the associated lifetime cancer and non-cancer chronic
risk to asbestos fibers inhalation. The general population exposure concentrations and inhalation lifetime
cancer risk are calculated using EquationApx L-l and EquationApx L-2. Lifetime cancer and non-
cancer chronic risk estimates are available in Asbestos Part 2 Draft RE - Risk for Calculator Consumer -
Fall 2023 (see Appendix L and Appendix C).
Various exposure duration (ED) and LTL IUR values were considered per COU for both non-cancer
chronic and lifetime cancer risk estimates. One (1) year is used for OES that are not stationary activities
such as demolitions, firefighting, and modification of machinery. Appendix L summarizes the
references, assumptions, and sources of information used for the 1 year ED for non-stationary
occupational activities related to firefighting and cleanup and extended to renovation and demolitions,
recognizing this is likely to overestimate ED. Twenty years were used as the number of years children
are assumed to reside in a single residential location for OESs that are stationary, such as waste handling
(landfills) and formulation of asbestos products. The 20-year assumption is based on expected number
of years children will remain in a household from birth to adulthood. This assumption considers
exposures at early stages and carrying that exposure throughout their entire lifetime, 78-year. Additional
ED considerations are available in Appendix L (TableApx L-l and TableApx L-2) for exposures
starting at 20 years of age and lasting for 30 years, representing young and mature adults that move
away from their childhood residence and remain in the same residence for 30 years and carry that
exposure throughout their entire lifetime, 78 years. Also considered in the appendix analysis is an
estimate for people that remain in the same residence their entire lifetime, 78 years. Table 5-17
summarizes main general population exposure duration assumptions and parameters used in estimating
risk.
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Table 5-17. General Population Exposure Duration Parameters
Parameter
Description
Values and Notation
Exposure duration (ED) for stationary
OES
OES examples: Waste handling at
landfills and Formulation of asbestos
products at specific locations/facilities
Exposures starting at birth and lasting 20
years of residing at same household.
Assumption of number of years children
reside in a single residential location.
Most protective assumption as the
exposure will be carried out through the
exposed population's lifetime.
ED = 20 years
Less-than-lifetime (LTL)
IUR = IUR(0,20) = 0.13
f/cc
Exposure duration for non-stationary
short duration OES
OES examples: Demolition,
renovation, maintenance of asbestos
containing structures,
Removal/maintenance of
machinery/appliances, and Firefighting
activities outside firehouse
Exposures starting at birth and lasting 1
year of residing at same household.
Assumption is that the activity
sporadically occurs for 1 year. Most
protective assumption as the exposure
will take place through the exposed
population's lifetime.
ED = 1
LTL IUR = IUR(0,1) =
0.01 f/cc
The Ambient Air Methodology utilizing AERMOD evaluated exposures to exposure points at eight
finite distances (5, 10, 30, 60, 100, 2,500, 5,000, and 10,000 m) and one area distance (100 to 1,000 m)
from a hypothetical releasing source for each OES. Exposure points for each of the eight finite distances
were placed in a polar grid every 22.5 degrees around the respective distance ring. This results in a total
of 16 exposure points around each finite distance ring for which exposures are modeled. Figure 5-3
provides a visual depiction of the placement of exposure points around a finite distance ring. Although
the visual depiction only shows exposure points locations around a single finite distance ring, the same
placement of exposure points occurred for all eight finite distance rings.
Figure 5-3. Modeled Exposure Point Locations for Finite Distance Rings for Ambient Air
Modeling (AERMOD)
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3251
3252
3253
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Exposure points for the area distance evaluated were placed in a cartesian grid at equal distances
between 200 and 900 m around each releasing facility (or generic facility for alternative release
estimates). Exposure points were placed at 100-meter increments. This results in a total of 456 exposure
points for which exposures are modeled.
5.1.4.2 Summary of General Population Ambient Air Exposure Concentrations
Releases of asbestos fibers to ambient air from various industrial or commercial activities, described by
occupational exposure scenarios (OES), were used to estimate environmental concentrations. Modeled
air concentration releases from industrial and commercial OESs emissions summarized in Section 3.3.1
were used to calculate risk to the general population using EquationApx L-l and EquationApx L-2
and the assumptions and parameters described in Section 5.1.4.1. The generic and specific facilities
modeled air concentrations were grouped and averaged (when appropriate) per OES, see Figure 5-4 and
Appendix F.3 for groupings and pivot tables.
1.0E+00
1.0E-01
^ 1.0E-02
J> 1.0E-03
a" 1.0E-04
| 1.0E-05
a 1.0E-06
| 1.0E-07
9 1.0E-08
'< 1.0E-09
J 1.0E-10
•2
Jj 1.0E-11
1.0E-12
1.0E-13
1.0E-14
Co-located General Population
I
i
i
i
i
i
i
i
i
i
1 10 30 60 I 100
1
I
I
V
General Population
I
100-1000 2500 5000 10000
Distance from Source (m)
¦ Waste Handling, Disposal, and Treatment Fugitive
¦ Handling Asbestos-Containing Building Materials During Maintenance, Renovation, and Demolition Activities Fugitive
¦ Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery Containing Asbestos Fugitive
¦ Handling Articles or Formulations that Contain Asbestos Fugitive
¦ Waste Handling, Disposal, and Treatment Stack
¦ Handling Asbestos-Containing Building Materials During Firefigliting or Other Disaster Response Activities Fugitive
¦ Handling Articles or Formulations that Contain Asbestos Stack
¦ Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery Containing Asbestos Stack
Figure 5-4. Modeled Ambient Air Concentrations by OES
Bar lines are the low- and high-end concentrations.
5.1.4.3 Weight of Scientific Evidence Conclusions for General Population Exposure
EPA modeled inhalation to asbestos fibers in ambient air. EPA considered multiple low-end, central
tendency and high-end inputs for ambient air modeled scenarios. Further, each scenario was split into
many sub-scenarios to fully explore potential variability. Modeled estimates were compared with
monitoring data to ensure overlap and evaluate the overall magnitude and trends. For example,
firefighting and fireproofing asbestos containing building material in Section 3.3.1.3. A qualitative
assessment of the uncertainty and variability associated with this approach is presented in Section
5.1.4.3.1 below and the overall confidence in the general population exposure scenarios inhalation risk
calculation is summarized in Table 5-18. All monitoring data used to estimate releases to ambient air
had data quality ratings of medium/high. For releases modeled with TRI/NEI/NRC data, the weight of
scientific evidence conclusion was moderate to robust.
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Table 5-18. Overall Confidence for General Population Exposure Scenarios
General Population Exposure Scenario
Environmental
Releases"
Overall Dispersion
Model Concentrations
Waste Handling, Disposal, and Treatment Fugitive
++ to +++
++
Handling Asbestos-Containing Building Materials During
Maintenance, Renovation, and Demolition Activities Fugitive
++ to +++
++
Use, Repair, or Disposal of Industrial and Commercial
Appliances or Machinery Containing Asbestos Fugitive
++ to +++
++
Handling Articles or Formulations that Contain Asbestos
Fugitive
++ to +++
++
Handling Asbestos-Containing Building Materials During
Firefighting or Other Disaster Response Activities Fugitive
++
++
11 See Section 3.2.1.2 and Appendix E.8.
5.1.4.3.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for
the General Population Exposure Assessment
Table 5-19. Qualitative Assessment of the Uncertainty and Variability Associated with General
Population Assessment
Variable Name
Relevant
Section(s) in Risk
Evaluation
Data Source
Uncertainty
(L, M, H)"
Variability
(L, M, H)"
General population exposure assessment
Environmental release
3.2
EPA modeled
M to L
H
estimates
Environmental
3.3
Extracted and evaluated
M
H
monitoring data
data (all) plus key studies
Exposure factors and
activity patterns
5.1.4.1
EPA Exposure Factors
Handbook
L
M
Key parameters for modeling environmental concentrations
Air modeling defaults:
meteorological data,
indoor/outdoor transfer
3.3.1, Appendix H
IIOAC/AERMOD
defaults
L
H
Particle deposition
3.3.4, Appendix H
(Air Section)
AERMOD
M
H
11 L = low; M = moderate; F
= high
EPA considered water, soil and land, and air pathways, and only the releases to air were moved on to
risk characterization, see Section 3.3. This may result in a potential underestimation of exposure in some
cases. Examples of exposure pathways that were not considered include incidental inhalation of
suspended soil during recreational activities. However, EPA expects these exposures to be less than
those that were included in the aggregate assessment. As such, their impact will likely be minimal and
would be unlikely to influence the overall magnitude of the results.
5.1.5 Aggregate Exposure Scenarios
EPA defines aggregate exposure as "the combined exposures to an individual from a single chemical
substance across multiple routes and across multiple pathways (40 CFR 702.33)." Aggregate exposure
can be done across several pathways and routes in the non-occupational and occupational risk
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assessments. However, the principal route of exposure considered in asbestos risk assessment to legacy
uses is inhalation; hence, EPA only considered aggregation across inhalation exposure scenarios and
COUs (Figure 5-5). If the individual estimates in the aggregation result in risk for a particular COU or
exposure scenario, this value is omitted from aggregation calculations, but the possibility of that specific
COU/activity occurring is described. When considering scenario specific estimates and aggregate
exposures, there is uncertainty associated with which scenarios co-occur in a given population group.
Further, there is variability within a given exposure scenario. For the same exposure scenarios, central
tendency estimates are more likely to co-occur than high-end estimates. To address this, EPA used
different combinations of exposures sampling from the entire distribution for all estimated exposures
that were not above the risk benchmark. This approach offers more clarity than static sensitivity analyses
based on combining assorted high-end and/or central tendency estimates of the component distributions.
For instance, combining the 95th percentile estimate of all component variables in an exposure equation
in a static sensitivity analysis may produce a conservative high-end estimate of exposure that cannot be
related to a specific percentile on the exposure distribution. Instead, EPA selected the risk estimates
when those were not above the risk benchmark and aggregated across exposure scenarios and
COUs/OES.
Populations COU Exposure Scenarios
Figure 5-5. Asbestos Aggregate Analysis Approach
5.2 Human Health Hazard
As described in Part 1 of the Risk Evaluation, the risk related to asbestos exposures are well established
and have been reviewed by several authorities. Data collected since the early 1970s from extensive
population studies with lengthy follow-up have increased our understanding of diseases linked to
asbestos exposure and reinforced the case for a causal relationship between asbestos exposure and
particular adverse health outcomes.
After a thorough and comprehensive investigation into the reasonably available evidence on the hazards
and health risks associated with asbestos, from data sources like the IRIS 1988 Assessment on Asbestos
(U.S. EPA. 1988b). IRIS 2014 Assessment on Libby Amphibole Asbestos (U.S. EPA. 2014c). National
Toxicology Program (NPT) 2016 Report on Carcinogens, Fourteenth Edition (NTP. 2016). NIOSH 2011
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Asbestos Fibers and Other Elongated Mineral Particles: State of the Science and Roadmap for Research
(NIOSH. 2011b). ATSDR 2001 Toxicological Profile for Asbestos (ATSDR. 2001). International
Agency for Research of Cancer (IARC) 2012 Monographs on the Evaluation of Carcinogenic Risks to
Humans. Arsenic, Metals, Fibres, and Dust. Asbestos (Chrysotile, Amosite, Crocidolite, Tremolite,
Actinolite, and Anthophyllite (IARC. 2012b). and World Health Organization (WHO) 2014 Chrysotile
Asbestos (WHO. 2014). the EPA determined that the human health hazards identified in the previous
reports are still relevant and valid. These studies continue to show that asbestos exposure is associated
with lung cancer, mesothelioma, laryngeal cancer and ovarian cancer (U.S. EPA. 2020c).
Cancer of Larynx and Ovaries
While lung cancer and mesothelioma have historically been the major focus of health studies and were
initially the focus in Part 1, it is recognized that laryngeal and ovarian cancers have more recently been
causally linked to asbestos exposure. Notably IARC monograph on epidemiological data showed that
there is a high incidence of lung cancer among workers who were exposed to chrysotile, amosite,
anthophyllite, and mixed fibers containing crocidolite and tremolite. Within the IARC monograph,
exposure to all asbestos fiber types was considered together as "cumulative exposure," so the
conclusions are summarized using that term here. There was also strong evidence for a positive
exposure-response relationship between cumulative asbestos exposure and cancer of the larynx and
ovaries as reported in several of the well-conducted cohort studies. This relationship was based on the
fairly consistent findings of both occupational cohort studies and case-control studies, as well as the
evidence for positive exposure-response relationships between cumulative asbestos exposure and
laryngeal cancer and/or ovarian cancer (IARC. 2012a). In the most recent IARC Monograph on asbestos
(IARC. 2012a). five highly positive cohort mortality studies of women with heavy occupational
exposure to asbestos were reviewed and it was concluded that the evidence clearly demonstrated a
causal association between exposure to asbestos and cancer of the ovary. Studies demonstrating that
women and girls with environmental exposure to asbestos, but not occupational exposure, showed
positive associations in both ovarian cancer incidence and death, providing additional support for the
relationship between asbestos exposure and ovarian cancer. The occupational workforce exposed to
asbestos has been predominately male, especially in occupations like mining, milling, shipyard work,
construction, and asbestos insulation. Thus, the published literature examining the association between
asbestos exposure and cancer of the ovaries has been more limited.
Colorectal Cancer
When considering cohort and case-control studies examining asbestos exposure and colorectal cancer,
several studies demonstrated a position relationship. However, evidence for a dose-response relationship
was not clearly evidence across the various cohorts studies (IARC. 2012a). Studies of populations with
prolonged and heavy exposure to asbestos that included high quality exposure assessment and had long-
term follow-up show positive exposure-response associations between asbestos exposure and colorectal
cancer, but several studies present conflicting results. Overall, the range of epidemiologic evidence is
not sufficient to establish causality in the association between asbestos and colorectal cancer (IARC.
2012a).
Overall, there was no new information for cancers such as mesothelioma, lung cancer, laryngeal,
ovarian, and colorectal cancers that substantively changed conclusions from prior assessments on the
causal relationship with asbestos exposure.
Besides cancer effects, it is well established that asbestos exposure can have adverse effects on the heart
and lungs as well as other non-cancer health outcomes. There is ample evidence that asbestos exposure
can have negative effects on the respiratory system, including asbestosis, non-malignant respiratory
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disease (NMRD), pulmonary function impairments, diffuse pleural thickening (DPT), and pleural
plaques. There are a number of immunological and lymphoreticular effects that have been hypothesized
but not substantiated. Numerous asbestos-exposed cohorts have shown evidence of asbestosis and
NMRD as a cause of death. Pulmonary function is decreased by DPT and pleural plaques. Because a
change in the distribution of pulmonary function in an exposed population causes a significant increase
in the proportion of people with a significant level of pulmonary impairment below a clinically adverse
level, pulmonary deficits are considered to be harmful for an asbestos-exposed populations (U.S. EPA,
2020c).
As described in the IRIS LAA Assessment (U.S. EPA. 2014c) the LAA epidemiologic database contains
research conducted in workplace settings as well as community-based investigations of workers, their
families, and other members of the general public. Occupational cohorts have included employees
exposed to LAA at the vermiculite mine and mill at the Zonolite Mountain facilities in Libby, Montana,
and at the manufacturing facility using the vermiculite ore in Marysville, Ohio. Additionally,
community-based studies have been carried out among residents in Libby, Montana as well as in the
vicinity of a Minneapolis, Minnesota industrial facility that produced vermiculite insulation. These
studies have looked at mortality due to cancer and non-cancer, effects on the lungs seen by x-ray exams,
pulmonary function testing, or respiratory symptoms, autoimmune illnesses, and the prevalence of
autoantibodies (U.S. EPA. 2014c).
Respiratory Effects
Several studies discussed mortality data for non-cancer respiratory diseases that had previously been
reported. Nonmalignant respiratory disease is a broad classification (International Classification of
Diseases [ICD]-9 codes 460-519) that encompasses asbestosis (ICD-9 code 501), several types of
pneumoconiosis, chronic obstructive pulmonary disease, asthma, pneumonia, and respiratory infections.
Comparing asbestosis to nonmalignant respiratory disease, the narrower the category, one would
anticipate more effect specificity of asbestos-related symptoms. Libby, Montana vermiculite mining and
milling worker cohorts' first research were based on a relatively modest number of nonmalignant
respiratory-related deaths (25); later studies saw more than 50 deaths in this category. However, a
pattern of increasing risk with increasing cumulative exposure is evident, with more than a 10-fold
increased risk of death from asbestosis and a 1.5- to 3-fold increased risk of nonmalignant respiratory
disease in the analyses using an internal referent group (Larson et al.. 2010; Sullivan. 2007; McDonald
et al.. 2004). The analytic strategy (e.g., use of a lag period to exclude exposures that occurred after the
onset of disease or use of a latency period to exclude cases that occurred before the effect of exposure
would be expected to manifest) and the cut-points for exposure categories varied among the studies
(U.S. EPA. 2014c).
According to the geographic-based research conducted by the ATSDR, the risk of developing asbestosis
increased as well, with SMRs of about 40 based on Montana rates and 65 based on U.S. comparator
rates (ATSDR. 2000). Since there was only one asbestosis-related death in the Marysville, Ohio worker
cohort, it is difficult to estimate the risk (Dunning et al.. 2012). Asbestosis is the interstitial pneumonitis
(inflammation of lung tissue) and fibrosis caused by inhalation of asbestos fibers. It is characterized by a
diffuse increase in collagen in the alveolar walls (fibrosis) and the presence of asbestos fibers, either free
or coated with a proteinaceous material and iron (asbestos bodies), which are the main symptoms of
asbestosis. Following lung damage, a series of processes that include inflammatory cell migration,
edema, cellular proliferation, and collagen accumulation lead to fibrosis. Asbestosis is linked to dyspnea
(shortness of breath), bibasilar rales, and alterations in pulmonary function, including a restrictive
pattern, a mixed restrictive-obstructive pattern, and/or a reduced diffusing capacity. In clinical practice,
tiny lung opacities on radiographic examination are the most typical signs of fibrotic scarring of lung
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tissue consistent with mineral dust and mineral fiber toxicity. Scarring of the lung's parenchymal tissue
causes changes in pulmonary function, such as restrictive pulmonary deficits brought on by the lung's
increased stiffness (reduced elasticity), impaired gas exchange brought on in part by thickening of the
alveolar wall, and occasionally mild obstructive deficits brought on by asbestos-induced airways disease
(U.S. EPA. 2014c).
The two main biological abnormalities that make up pleural thickening brought on by mineral fiber
exposure are localized pleural plaques in the parietal (outer) pleura and widespread pleural thickening of
the visceral (inner) pleura. Pleural and parenchymal abnormalities (pathological, structural
modifications) which can be found by radiography or other methods of imaging, can serve as evidence
of the risk of respiratory disease. The International Labour Organization (ILO) of the United Nations
developed these criteria to standardize descriptions of effects and to increase inter-rater agreement and
accuracy for interpreting chest radiographs in pneumoconiosis. Standard radiographs can detect both of
these types of pleural thickening; however, smaller/thinner plaques and thinner diffuse thickening could
not be seen, especially if they are not calcified or hidden by other typical chest structures. High
resolution computed tomography is a radiographic technique that is more sensitive and specific than
conventional chest x-rays; for example, it can detect pleural abnormalities that are not visible on
conventional x-rays and more reliably exclude fat tissue that can occasionally be mistaken for pleural
thickening on conventional x-rays (U.S. EPA. 2014c).
Cardiovascular and Immunologic Effects
Research on non-cancer health impacts happening beyond the pleura and respiratory system is more
limited. Studies examining effects in workers from the Libby, MT considered cardiovascular disease and
related mortality. As described in Section 4.1.3.1 of the IRIS LAA Assessment, weak associations were
identified; however, the observed associations may be influence by smoking patterns and/or underlying
respiratory disease that may have preceded cardiovascular effects. Other research looked at the
relationship between asbestos exposure and immunological indicators including autoantibodies and
autoimmune diseases. Evidence is more thoroughly described in Section 4.1.3.2 of the IRIS LAA
Assessment, which includes discussion of three community-based cohort studies. Across these studies,
the data indicates some perturbation in immune function, but it is challenging to draw conclusions about
the role of asbestos in autoimmune illness due to limitations in the quantity, breadth, and design
methodology of these studies. Studies on chronic inflammation after asbestos inhalation exposure have
been conducted for many years in both people and animals. As is the case with cardiovascular diseases
that may be associated with asbestos exposure, it is likely that the respiratory effects observed precede
altered immunologic activity (U.S. EPA. 2014c).
For Part 2, EPA employed a systematic review approach to identify the relevant epidemiologic evidence
and to determine if new information is available that would extend or substantively alter the well-
established existing conclusions on asbestos exposure and human health. The systematic review
approach is described in the Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for
Chemical Substances (U.S. EPA. 2021). EPA reviewed the epidemiologic data examining human health
hazards and determined the most informative hazard studies to be those that included data and employed
methodologies informing a dose-response relationship. Studies that are useful for dose response are
generally based on historical occupational cohorts with the longest follow-up for each cohort or the most
pertinent exposure-response data when a cohort has been the subject of more than one publication.
Consideration of studies that could inform a dose-response relationship were not limited by exposure
route. Inhalation and ingestion are the main exposure pathways of concern. Dermal contact is not
regarded as a primary exposure route because fibers are inert and therefore do not penetrate through the
skin. Dermal exposures were recognized as a potential exposure route in the SR process, but no dermal
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studies were identified in the process. Although studies of oral exposure were identified and considered,
these studies were not considered informative for dose-response analysis in the context of existing
assessments and the robust data available for inhalation exposures.
Exposure via the oral route was evaluated in the 2012 IARC Monograph. This report acknowledges that
several individual studies show a positive association between ingestion of asbestos via drinking water
and stomach and colorectal cancer across several different communities; however, there are studies that
did not find an association. The Monograph describes two systematic reviews that reached an overall
conclusion that information was insufficient to assess the risk of cancer (stomach and colorectal) from
asbestos in drinking water or there was no clear pattern of association between asbestos in drinking
water and stomach cancer (stomach and colorectal) (IARC. 2012a).
Through the systematic review process, EPA identified nine oral studies. Three of these studies were
considered in the IARC Monograph. Two studies conducted by Polissar et al. (Polissar et al.. 1984.
1983) were not included in the IARC Monograph, but they were similar to the 1982 study by Polissar
et.al, which was included in the IARC report and identified in our systematic review. These
epidemiologic studies conducted in western Washington state found inconclusive evidence or evidence
due to chance for the association between asbestos in drinking water and gastrointestinal tract,
esophagus, stomach, and pancreatic cancers as well as esophagus, stomach, digestive-related organs, and
pancreatic malignancies (Polissar et al.. 1984. 1983; Polissar et al.. 1982). Three other studies by Haque
et al., (Hague et al.. 1998; Hague et al.. 1996; Hague and Kanz. 1988) investigated the effects of
asbestos fibers on several maternal and fetal medical, demographic, and environmental factors, as well
as the asbestos loads in stillborn infants from transplacental transfer or ingestion or inhalation of
contaminated amniotic fluid following premature rupture of membranes. Ultimately, these studies found
detectable amounts of fibers in placenta and fetal tissues of stillborn babies compared to controls (live-
born placenta). However, the presence of asbestos fibers was not linked to premature membrane rupture.
Asbestos fibers were found throughout the whole gestation period and did not correlate with gestational
age. The lack of a maternal history of work involving asbestos raises the possibility that the fibers were
ingested from ambient exposure (Hague et al.. 1998; Hague et al.. 1996).
Inhalation is the critical route of exposure as the respiratory tract is the most sensitive to asbestos fibers
when compared to dermal and oral exposures, and an IUR value and a POD based on epidemiologic
studies are available. Quantitative dose-response analysis was not conducted for oral and dermal routes
of exposure based on the limited information available for these exposures. In addition, respiratory
effects are the most sensitive and early effects observed across the database of information.
5.2.1 Dose-Response Considerations: Cancer
In keeping with the various occupational epidemiological study designs which were discussed in
previous risk assessments, EPA is using dose-response and exposure-response relationship
interchangeable because it describes the amount of exposure/dose a person is exposed to. Through the
systematic review process and fit-for-purpose filtering that was employed (U.S. EPA. 2021). 16 cohorts
were identified for consideration in assessing dose response of cancer outcome related to asbestos
inhalation exposures. Most of these cohorts were identified and considered in previous assessments,
including the 1988 IRIS Asbestos Assessment, the 2014 IRIS LAA Assessment, and the 2020 Part 1 of
the Risk Evaluation for Asbestos. Only one cohort was identified that was not previously considered in a
prior EPA assessment—and as a community-based cohort (Wittenoom, Australia, Residents Cohort),
rather than an occupational cohort—this study was unigue. In the consideration of these cohorts in the
previous assessments, with the exception of the Wittenoom Cohort, IURs were developed for use in risk
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assessment. Each of these IURs is described in the White Paper (U.S. EPA. 2023 o) and summarized
here.
1988 IRIS Asbestos Assessment
The IRIS Asbestos Assessment, released in 1988 (U.S. EPA. 1988b). utilizes the Airborne Asbestos
Health Assessment Update from 1986 (U.S. EPA. 1986a). The latter was developed as the scientific
foundation to support EPA's review and revision of the designation of asbestos as a hazardous air
pollutant under the 1973 National Emission Standards for Hazardous Air Pollutants (NESHAP) under
the 1977 Clean Air Act Amendments (U.S. EPA. 1986a). The original designation of asbestos was based
upon a qualitative review of the evidence prior to 1972 establishing associations between exposure and
carcinogenicity. The objectives of the Airborne Asbestos Health Assessment Update (U.S. EPA. 1986a)
were to identify any new asbestos-related health effects from studies published after 1972, examine the
dose-response relationship, and establish unit risk values for asbestos, if warranted.
The assessment included occupational studies with exposures to any of the principal commercial
varieties of asbestos fibers (i.e., amosite, anthophyllite, crocidolite, and chrysotile). A total of 14
occupational studies provided data for a dose-response assessment, however only 6 of those studies were
considered because of the robustness of the data and the OQD rating of medium or high (Appendix I).
The data for a best estimate of increased risk of lung cancer per unit exposure are provided across a
range of occupational activities. Studies of mining and milling were excluded due to a substantial
difference in risk observed and the notion that exposure assessment in these operations is significantly
more challenging due to a wide array of fibers being present. Factories have a more limited set of
sources of dust and fibers, making fiber counts more straightforward and less likely to be impacted by
the presence of other fibers. In deriving the overall slope factor for lung cancer (Kl), the geometric mean
was calculated from the 14 epidemiologic studies, representing exposures to a mix of fibers from
chrysotile, amosite, and crocidolite.
A cancer slope factor for mesothelioma (Km) was derived using information from the same 14 studies.
Four of these studies examined mortality resulting from mesothelioma. Estimates of mesothelioma in the
other ten studies were developed by determining the ratio of lung cancer to mesothelioma in the four
studies examining both, and then applying an adjustment to lung cancer rates in the ten studies that did
not examine mesothelioma. In addition, there was consideration of uncertainty resulting from exposure
to crocidolite which was postulated to be more potent; however, examination of potency revealed that
the impact of this uncertainty was minimal. Overall, there were no outliers in slope factors dervied for
each study, so the geometric mean was used to calculate the slope factor for mesothelioma^. S. EPA.
1988b).
The cancer slope factors for lung cancer and mesothelioma were separately derived and then statistically
combined. Subsequently, a life table analysis was conducted using the Kl and Km to represent the
epidemiologic data, a relative risk model for lung cancer, and an absolute risk model for mesothelioma
with linear low dose extrapolation to arrive at an IUR of 0.23 per fiber/cc. An important observation
from this assessment is that risk from lung cancer increases with time since first exposure and death
from mesothelioma increased decades after onset of exposure. Limitations of the analysis in this
assessment include (1) variability in the exposure-response relationship at high exposure; (2) uncertainty
in extrapolating to much lower exposures (i.e., background exposures that can be l/100th the levels seen
in occupational settings); and (3) uncertainties in converting between detection methods (e.g., optical
fiber counts, mass determination) (U.S. EPA. 1988b).
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2014 IRIS Libby Amphibole Asbestos Assessment
The IRIS LAA Assessment, released in 2014, included a detailed toxicological review that provides the
scientific foundation to support the risk and dose-response assessment of chronic inhalation exposure
specific to LAA in the Rainy Creek complex and from the vermiculite mine near Libby, Montana (U.S.
EPA. 2014c). The LAA Assessment evaluated the possible risks associated with exposure to LAA,
including those related to cancer and non-cancer health effects, and presents risk values for use in risk
assessments, including an RfC for non-cancer health effects (summarized below in Section 5.2.2 and an
IUR to address cancer risk. The LAA Assessment considered several occupational and community-
based cohorts for dose-response assessment (see Figure 4-1 in the LAA Assessment); however, for
cancer dose-response, the Libby, Montana, Vermiculite Milling and Mining Cohort examining workers
participating in mining and milling activities at the mine in Libby, Montana, and a plant in Marysville,
Ohio, as being most relevant for dose-response consideration.
This cohort was determined to have the most robust data for dose-response assessment for numerous
reasons, including the use of individual level exposure data based on impinger and PCM measurements,
complete demographic data, and vital status with extended follow-up through 2006 (approximately 30
years of follow-up). For mesothelioma mortality in this data set, Poisson modeling was conducted to fit
mortality data and exposure data with a range of exposure metrics. The best model was based upon a
subcohort with employment beginning in 1959 and a cumulative exposure metric with a 5-year half-life
and a 10-year lag time. The central estimate for Km was 3.11 x 10 4 per fibers/cc. Following selection of
the Km, a lifetable procedure was applied to the U.S. general population using age-specific mortality
statistics to estimate the exposure levels that would be expected to result in a 1 percent increase in
absolute risk of mesothelioma over a lifetime of continuous exposure. Linear low-dose extrapolation
was used to find an effective concentration corresponding to the central tendency, which was estimated
to be 0.032 per fiber/cc and 0.074 per fiber/cc when adjusted to account for under-ascertainment of
mesothelioma.
Lung cancer unit risk values were also calculated separately and based on a subcohort of the Libby,
Montana, workers hired after 1959. Multivariate extended Cox models were run with a range of
exposure metrics, and the best fit was based on cumulative exposure with a 10-year half-life and a 10-
year lag. The resulting KL from this model was 0.0126 per fiber/cc-yr. As was done for the
mesothelioma cancer slope factor, a life-table analysis was applied to the KL to determine an exposure
level of asbestos expected to result in a 1 percent increase in relative cancer risks when taking into
account age-specific background risk. The corresponding effective concentration relating to the central
tendency was 0.0399 per fiber/cc for a lifetime continuous exposure with an upper bound unit risk of
0.0679 per fiber/cc.
The statistical derivation of a combined upper bound unit risk value accounted for overprediction
resulting from combining individual upper bound estimates. The upper bound combined risk from the
best fitting models applied to individual-level data from the Libby, Montana, workers was 0.17 per
fiber/cc. The 2014 IRIS LAA Assessment notes some limitations, including the difficulty in controlling
for smoking as a confounder, the potential for under-ascertainment of mesothelioma, and uncertainties
in the exposure measurements in the facility.
Part 1 Risk Evaluation for Asbestos
The most recent asbestos IUR was developed as part of the Risk Evaluation for Asbestos Part 1:
Chrysotile Asbestos (U.S. EPA. 2020c). An IUR of 0.16 per fiber/cc was derived based upon thorough
consideration and analysis of data from epidemiological studies on mesothelioma and lung cancer in
cohorts of workers using chrysotile asbestos. Data from several cohorts was available for dose-response
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modeling following a systematic approach to literature identification and evaluation. Ultimately, data
from cohorts of workers in textile plants in North and South Carolina were selected for IUR derivation.
For the NC cohort, individual-level exposure-response data was available for lung cancer in Loomis et
al. (2009) and Elliott et al. (2012) as well as mesothelioma in Loomis et al. (2019). For these studies, the
Part 1 Risk Evaluation presents cancer potency values based on Poisson regressions of the individual-
level data using both logistical and additive relative rate model forms with adjustment for age, sex, race,
calendar period, and birth cohort (see Table 3-4 in (U.S. EPA. 2020c)). For the SC cohort, individual-
level data was available for lung cancer in Hein et al. (2007) and (Elliott et al.. 2012) as well as for
mesothelioma from Berman and Crump (2008). Lung cancer potency values for these studies were
based on Poisson regression models using a linear relative rate model form with adjustment for sex,
race, and age. Mesothelioma cancer potency values were reported in Berman and Crump (2008) based
on analyses of the original cohort data using the Peto model (see Table 3-3 in (U.S. EPA. 2020c)).
The 2014 LAA Assessment and Part 1 describes uncertainty related to under-ascertainment of
mesothelioma as an International Classification of Diseases (ICD) code specific to mesothelioma that
was not available prior to 1999. An adjustment factor was applied to the IUR to account for this under-
ascertainment in the same way the Libby IUR was adjusted. Additionally, the IUR was adjusted to
account for cancer risk from other cancer endpoints beyond lung cancer and mesothelioma. As
explained in Section 3.2.3.8.1 of Part 1 (U.S. EPA. 2020c). IARC concluded that exposure to asbestos is
causally related to lung cancer and mesothelioma as well as laryngeal and ovarian cancer (U.S. EPA.
2020c; Straif et al.. 2009). Data was not available to derive potency factors for laryngeal and ovarian
cancer, so an adjustment factor was developed to account for potential underestimation of cancer risk
when only considering data for lung cancer and mesothelioma.
For each modeling result from the NC and SC data sets (U.S. EPA. 2020c). the unit risks were
calculated separately for lung cancer and mesothelioma. Lung cancer unit risks were adjusted to account
for other cancers and mesothelioma unit risks were adjusted to account for under-ascertainment. The
unit risks were then statistically combined for central unit risk and upper bound risk. Of the available
IURs from modeling results, the median IUR was ultimately selected because there was low model
uncertainty (see Table 3-12 in (U.S. EPA. 2020c)). The median lifetime cancer incidence IUR was 0.16
per fiber/cc based upon a linear model of the data from the NC textile workers cohort (Elliott et al..
2012).
Part 1 notes a few important uncertainties in the 0.16 per fiber/cc IUR (see Section 4.3.5 in (U.S. EPA.
2020c)). First, PCM measurements were used despite TEM being a more precise analytical technique.
However, it was determined that when TEM and PCM were available in the same data set, TEM and
PCM model results were similar. Thus, this uncertainty was considered to be low for the NC textile
worker cohort. Another source of uncertainty in exposure measurements is the use of impinger sampling
data for early asbestos exposures. Prior to 1965,the majority of the data on asbestos workers' exposures
came from total dust concentrations determined with a midget impinger, which were frequently
employed as area samplers in place of personal samplers In general, there were weak associations
between fiber concentrations and midget impinger particle counts determined with bright field
microscopy (U.S. EPA. 1986a). The most robust approach to account for this is to use paired and
concurrent sampling data to derive a conversation factor, and this was performed in the analysis of the
NC and SC textile cohorts resulting in low uncertainty. When considering uncertainties related to
outcome data, use of mortality data rather than incidence, which was not available, was of concern. To
account for this, background rates of lung cancer incidence were used in lifetable analyses. However,
this was not possible for mesothelioma. While this remains a bias, it is noteworthy that median survival
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for mesothelioma is less than 1 year. Finally, confounding must be considered with regard to
uncertainties. Smoking is considered a strong confounder for lung cancer related to asbestos exposure,
but in the NC and SC cohorts, confounding was deemed to be low because regression models accounted
for birth cohort that would reflect changes in smoking rates over time. Additionally, it is likely that
smoking rates among workers were similar across facilities and occupations. Smoking is not a
confounder for mesothelioma.
5.2.1.1 Inhalation Unit Risk for Part 2
All three of the EPA's currently available IURs (0.23 per fiber/cc, 0.17 per fiber/cc and 0.16 per
fiber/cc) are numerically very similar, despite decades of epidemiologic research conducted in a variety
of occupational settings, using a variety of exposure measurement techniques and exposure assignment
approaches, and based on a wide range of dose response modeling with the application of adjustment
factors. Sensitivity analyses were conducted on IURs of 0.23 per fiber/cc and 0.2 per fiber/cc, and
observed risk were not different regardless of values use (Appendix K).
The IUR of 0.16 per fiber/cc presented in Part 1 of the Risk Evaluation for Asbestos (U.S. EPA. 2020c)
benefits from the most recent data available and generally, the longest follow-up periods. Advanced
exposure measurement methods are reflected in the underlying data resulting in exposure estimates that
are of high confidence. Furthermore, longer follow-up times increase the statistical power of the study as
more mortality is observed. Other notable strengths include accounting for laryngeal and ovarian
cancers, which are causally associated with asbestos exposure, and accounting for under-ascertainment
of mesothelioma.
The IUR of 0.17 per fiber/cc presented in the IRIS LAA Assessment (U.S. EPA. 2014c) has similar
strengths and limitations as the chrysotile IUR. Robust analyses were conducted based on
very detailed individual-level exposure measurements and outcome data for lung cancer and
mesothelioma as the cohort was established from one operation, the mine in Libby, Montana. There
were not sufficient data on laryngeal or ovarian cancers in this cohort for quantitative consideration, but
under-ascertainment of mesothelioma was accounted for. The data used in the analysis was
comprehensive and yielded quantitative analyses of high confidence.
The earliest IUR of 0.23 per fiber/cc presented in the IRIS Asbestos Assessment (U.S. EPA. 1988b) was
developed to describe risks related to all asbestos fiber types. Development of this IUR was based on
historically robust data at a time when standard fiber measurement methods had not yet been established
and reporting and publication standards were highly variable. A major strength of this IUR is that it
represents exposures to a range of fiber types and is most appropriately applied to describe risks related
to mixed-fiber exposures, which is pertinent to exposure scenarios in Part 2 of the Risk Evaluation for
Asbestos. The authors of the report acknowledged this objective when they described the use of data
from all cohorts and not isolating data from the cohort with the most detailed exposure assessment that
may have been specific to only a single fiber.
An IUR of 0.2 per fiber/cc is a representative value that reflects the strength and uncertainties of each
individual IUR. When considering standard practice of reporting IURs with precision to one significant
digit, each of the existing IURs would round to 0.2 per fiber/cc. Selecting an IUR of 0.2 is well-
supported and takes into account a broad range of applicable information. This value reflects exposures
in a variety of settings and levels, an array of asbestos fibers, and relevant cancer outcomes. Exposure
scenarios described herein do not pertain to specific fiber types (e.g., chrysotile and LAA). Specifically,
for asbestos-containing building materials, exposure to mixed fiber types is expected.
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The use of an IUR of 0.2 per fiber/cc takes into account the existing IUR's developed by the EPA since
1988 as well as the newer body of evidence, that produce a numerically similar IUR 0.17 per fiber/cc
and 0.16 per fiber/cc. Exposure sensitivity analysis did not show any increased or decreased risk from
using an IUR of 0.2 per fiber/cc vs. 0.23 per fiber/cc, 0.17 per fiber/cc and 0.16 per fiber/cc (Appendix
K).
5.2.1.2 Uncertainties
Inherent strengths and uncertainties pertain to each IUR, and all were developed for a distinct purpose
and application. The IUR of 0.16 per fiber/cc (U.S. EPA. 2020c) was strictly limited to exposures to
chrysotile asbestos and is therefore most appropriately applied in cases where exposures are chrysotile-
specific.
As described in Section 5.2, the comprehensiveness of the data for the IRIS LAA Assessment IUR of
0.17 per fiber/cc (U.S. EPA. 2014c) yielded quantitative analyses of high confidence. However, this IUR
is based on data specific to scenarios of exposure to only LAA, and therefore, is most appropriately
applied in risk estimates based on Libby-specific exposures.
Although development of the IUR of 0.23 per fiber/cc (U.S. EPA. 1988b) was robust, additional
uncertainty exists in the exposure measurement provided in the published studies. It is important to note
that EPA technical experts were diligent in advancing their understanding and use of data beyond what
was available in original publications to reduce uncertainties, as reflected in the 1988 Asbestos
Assessment, and related publications.
Part 1 notes a few important uncertainties in the IUR (see Section 4.3.5 in (U.S. EPA. 2020c)). First,
PCM measurements were used despite TEM being a more precise analytical technique. However, it was
determined that when TEM and PCM were available in the same data set, TEM and PCM model results
were similar. Thus, this uncertainty was considered to be low for the NC textile worker cohort. Another
source of uncertainty in exposure measurements is the use of impinger sampling data for early asbestos
exposures. The most robust approach to account for this is to use paired and concurrent sampling data to
derive a conversation factor, and this was performed in the analysis of the NC and SC textile cohorts
resulting in low uncertainty. When considering uncertainties related to outcome data, use of mortality
data rather than incidence, which was not available, was of concern. To account for this, background
rates of lung cancer incidence were used in lifetable analyses. However, this was not possible for
mesothelioma. While this remains a bias, it is noteworthy that median survival for mesothelioma is less
than 1 year. Finally, confounding must be considered with regard to uncertainties. Smoking is
considered a strong confounder for lung cancer related to asbestos exposure, but in the NC and SC
cohorts, confounding was deemed to be low because regression models accounted for birth cohort that
would reflect changes in smoking rates over time. Additionally, it is likely that smoking rates among
workers were similar across facilities and occupations. Smoking is not a confounder for mesothelioma.
In Part 1 of the Risk Evaluation, this IUR was applied for all chrysotile asbestos exposure scenarios,
with less-than-lifetime adjustments applied where appropriate for less-than-lifetime exposures. Risk
determinations were based, in part, on quantitative risk characterization computer with this IUR. Risk
management rulemaking that is currently underway will address the unreasonable risk identified in Part
1 of the Risk Evaluation for Asbestos (U.S. EPA. 2020).
5.2.2 Dose-Response Considerations: Non-cancer
Application of the systematic review approach described in White Paper (U.S. EPA. 2023 o) and
Protocol (U.S. EPA. 2021) resulted in the identification of seven cohorts for consideration in assessing
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dose response of non-cancer outcomes related to asbestos exposures. All of the cohorts identified
examined inhalation exposures. Epidemiologic studies examining oral or dermal exposures with dose-
response information were not identified by the systematic review approach. The outcomes assessed in
the identified cohorts included non-cancer mortality (including asbestosis and pneumoconiosis), pleural
changes/thickening, and lung function changes. Some of these cohorts were identified and considered in
the IRIS LAA Assessment (U.S. EPA. 2014a). which is the only EPA assessment that has quantitatively
considered non-cancer effects to date.
In evaluating all of the cohorts with dose-response information to determine which provides the most
robust and relevant data for dose-response analysis (see Appendix C of the White Paper) an
occupational cohort from the O.M. Scott plant in Marysville, OH described by Lockev et al. (1984) and
followed up by Rohs et al. (2008) was selected. This cohort was selected for multiple reasons: (1)
absence of confounding from community and residential exposure; (2) availability of data on significant
covariates (e.g., BMI); (3) exposure-response relationship defined for lower cumulative exposure levels
(especially for workers hired in 1972 or later and evaluated in 2002-2005); (4) over 50 years of follow-
up; (5) use of more recent criteria for evaluating radiographs (ILO, 2002); (6) availability of high-quality
exposure estimates based on numerous industrial hygiene samples and work records; and (7) availability
of data on time since first exposure (TSFE) matched to the exposure data (U.S. EPA. 2014a). This
cohort also has reliable individual-level measurements of asbestos exposures and detection of pleural
thickening, an early adverse effect. The other six cohorts OPPT identified, which were not within the
scope of the IRIS LAA Assessment, were less suitable for non-cancer dose-response assessment because
the outcomes examined were less sensitive (i.e., mortality-related outcomes) and/or because there was
greater uncertainty in the exposure data (e.g., community-based measurements rather than personal
sampling). Generally, for dose-response assessment, preference is given to studies examining the most
sensitive outcome(s), so although mortality can be used in the assessment, it is less sensitive than a well-
described outcome preceding mortality from a disease state. Appendix C in the White Paper (U.S. EPA.
2023o) provides more details on the dose-response considerations for each cohort.
The O.M. Scott Marysville, Ohio, Plant Cohort included a total of 512 workers in the 1980 investigation
of pulmonary effects in Ohio plant workers (Lockev et al.. 1984). Workers were drawn from a variety of
departments/facilities, including production and packaging of commercial products, maintenance,
research, the front office, and the polyform plant. The initial study of this cohort utilized air sample
measurements collected in 1972 to assign cumulative worker exposures based on individual job
histories. Outcomes were assessed by radiologist readings of chest x-ray films and spirometry for lung
function measures. A follow-up of this cohort was conducted nearly 25 years later, providing more
robust exposure-response analyses (Rohs et al.. 2008).
In this follow-up analysis (Rohs et al.. 2008). the cohort was limited to men hired after 1972 as there
was more certainty in the exposure estimates; post-1972 measurements were taken by industrial
hygienists who followed employees during the course of their work with sampling devices. Sampling
data were also collected within personal breathing zones beginning in 1977. Detailed employee records
were used to construct exposure histories and estimate cumulative asbestos exposures for each
individual. Health outcomes were assessed in 1980 and between 2002 and 2005; however, the use of
different protocols was considered an uncertainty and the later film readings were deemed more reliable.
In addition, the later radiographic films extended the follow-up time by roughly 25 years, which is
important given the latency of effects. These considerations resulted in a sub-cohort of 119 men for
which robust exposure and outcome data were available for dose-response modeling. With the data from
the sub-cohort, a range of dose-response model forms were evaluated, but the most suitable model
fitting results were obtained using the Dichotomous Hill model using the mean exposure and pleural
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thickening. Time since first exposure (TSFE) has been demonstrated to be an important predictor of
effect, data from the broader cohort (including those hired prior to 1972) was used to develop a fixed
regression coefficient that was included in the model. In the modeling, a benchmark response (BMR) of
10 percent was used based on considerations of adversity for LPT. The benchmark concentration is the
level of exposure expected to result in the excess risk defined by the BMR. More specific details and
results of model-fitting are presented in Section 5.2.2.6.1 in the IRIS LAA Assessment (U.S. EPA.
2014c). A POD based on a 10 percent BMR for LPT was calculated to be 2.6x 10~2 fiber/cc.
The IRIS program noted important uncertainties related to the underlying evidence base for this POD
and applied UFs to account for intraspecies variability (UFh of 10), database uncertainty (UFd of 3), and
data-informed sub chronic-to-chronic uncertainty (UFs of 10) in the 2014 LAA Assessment (U.S. EPA.
2014c).
• Regarding the UFh, the occupational cohort included individuals healthy enough to work, and
when taking into account human variability, it is plausible that there are more sensitive
individuals in the population. This uncertainty remains at this time; thus, UFh of 10 continues to
be applied.
• Regarding the UFd of 3, applied in the IRIS LAA Assessment because of the limited number of
cohort studies evaluating the most sensitive non-cancer effects of chronic asbestos exposure, the
Agency has reevaluated the appropriateness of UFd of 3 in light of the systematic review. As
described in Section 4, no new cohort studies have been published that would inform the dose
response relationship for hazards beyond pleural effects and asbestosis for the non-cancer POD.
Therefore, the Agency will continue to apply a UFd of 3.
• Regarding the UFs, it was anticipated that if the cohort had been followed for longer, even more
cases of LPT would have been identified. The cohort used to derive the 2014 IRIS RfC, O.M.
Scott Marysville, Ohio, was followed for approximately 30 years. The IRIS LAA Assessment
determined that it was appropriate to apply a UFs because even 30 years of observation is
insufficient to describe lifetime risk of LPT, which continues to increase over a person's lifetime
(see page 5-42 of the IRIS LAA Assessment for further rationale for applying the UFs (U.S.
EPA. 2014a)). The IRIS LAA Assessment, therefore, derived a data informed UFs of 10 based
on the fact that "the central estimate of the risk at TSFE = 70 years is ~10-fold greater than the
central estimate of the risk at TSFE = 28 years (from 6 to 61%)" (see page 5-43 of the IRIS LAA
Assessment for further details (U.S. EPA. 2014a). TSFE in the model was set at 28 years due to
limitations in the statistical uncertainty.
5.2.2.1 Point of Departure for Part 2
In thoroughly reviewing the reasonably available information and the LAA POD from the IRIS
assessment, using the POD in Part 2 of the Risk Evaluation is a reliable approach to quantitatively
consider non-cancer risks from asbestos exposures. While there is some uncertainty in application of a
Libby-specific POD for exposures to a broader range of asbestos fibers, the uncertainty of using other
studies for quantitative assessment would be even greater given the limited exposure characterization for
those cohorts (see Appendix M in this document and Appendix C of the White Paper). For example, for
the SC Vermiculite Miners Cohort, non-cancer outcomes were only categorically analyzed as exposed
and unexposed. In addition, details of the exposure assessment are insufficient for dose-response
assessment, and there is a lack of information on TSFE. The Anatolia, Turkey, Villagers Cohort
constructed individual-level exposure estimates, but these were based on broad assumptions of time
spent indoors, outdoors, and sleeping. The other cohorts available for dose-response assessment
similarly had exposures to a single fiber type and examined mortality as the outcome, which would not
be representative of the more sensitive effects known to result from asbestos exposures.
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Based on the comprehensive approach to identify and evaluate the relevant epidemiologic literature for
dose-response assessment of non-cancer effects resulting from asbestos exposures, use of the POD
presented in the IRIS LAA Assessment is appropriate. In the IRIS LAA Assessment, LPT was selected
as the critical non-cancer effect for POD selection with a BMR of 10 percent extra risk. LPT, as
indicated by the presence of pleural plaques is the most effective endpoint to select because it is the
outcome that generally appears at lower doses after asbestos inhalation exposure. Reduced lung function
is typically linked to LPT, which is an irreversible structural and pathological modification of the pleura.
Using a non-lethal POD, like LPT, instead of asbestosis or mortality means that if the EPA could
prevent people from developing LPT, this would mitigate them getting asbestosis and avoid mortality. In
summary, non-cancer risks will be calculated using the IRIS LAA POD of 2.6x 10~2. The uncertainty
factors presented in the IRIS LAA Assessment will be considered in establishing the benchmark MOE,
described in Section 5.3.
5.2.3 Mode of Action Considerations
EPA assessed potential modes of action (MOA) for asbestos based on existing literature, including
previous EPA IRIS Assessment (U.S. EPA. 2014c). EPA Asbestos Part 1 Risk Evaluation (U.S. EPA.
2020c). and proposed mechanisms by IARC (2012a). It has been hypothesized that asbestos, may act
through multiple MO As with adverse health effects resulting from the collective interaction of various
toxicity determinants. Additionally, physical, and chemical characteristics of fibers such as dimensions,
chemical composition, surface characteristics, and biopersistence appear to can influence their
pathogenic potential. Although the precise MOA of asbestos induced malignant and non-malignant
respiratory diseases remains unclear, numerous studies have proposed several direct and indirect
mechanisms to explain the biological activity of asbestos fibers (U.S. EPA. 2014c; IARC. 2012a;
ATSDR. 2001). Furthermore, both in vitro and in vivo studies have indicated that asbestos fiber
exposure could lead to sustained oxidative stress due to the generation of reactive oxygen species
through interactions with macrophages and the production of hydroxyl radicals from surface-bound iron
(U.S. EPA. 2020c. 2014c; IARC. 2012a). Persistent oxidative stress and chronic inflammation induced
by asbestos fibers have been linked to the aberrant activation of intracellular signaling pathways, which
may lead to increased cellular proliferation, impaired DNA damage repair, and oncogene activation
(U.S. EPA. 2014c; IARC. 2012a). Asbestos fibers have also been shown to induce direct genotoxicity
through interference with mitotic spindle leading to chromosome aberrations (IARC. 2012a). Overall,
existing evidence suggests that oxidative stress, chronic inflammation, and associated cell injury may
play pivotal roles in both cancerous and non-cancerous health effects following asbestos exposure.
However, the extent to which these and other biological alterations serve as key events in asbestos-
related pathogenicity has not yet been fully elucidated.
Overall MOA Conclusions
Although the evidence largely indicates an MOA involving long-term interplay between chronic
oxidative stress and persistent inflammation, the available data are insufficient to establish an MOA for
non-cancer or cancer health effects following asbestos exposure. Hence, the cancer unit risk for
inhalation exposure is calculated using a linear approach in accordance with the default recommendation
of the 2005 Guidelines for Carcinogen Risk Assessment (U.S. EPA. 2005).
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Asbestos - Human Health Risk Characterization (Section 5.3):
Key Points
EPA evaluated all reasonably available information to support human health risk characterization.
The following bullets summarize the key points of this section of the draft Part 2 risk evaluation:
• Inhalation exposures drive risks to workers in occupational settings, and both lifetime cancer
ELCRs and non-cancer chronic MOEs are in the range of 1.8xl0~7 to 1.5x10 3 and, 0.16 to 1,424,
respectively.
• The take-home exposure risk assessment lifetime cancer and non-cancer risk values, ELCR and
MOEs, are in the range of 4.8x 10~9 to 3.7x 10~4, and 11 to 840,437, respectively for most high-end
exposure activities, such as demolition/renovation, career firefighting, repair/removal of
machinery, handling of articles or formulations, and handling waste.
• DIY activity-base exposures result in lifetime cancer and non-cancer risk values, ELCR and
MOEs, range of 8.4xl0~9 to 2.3xl0~2, and 0.1 to 774,424, respectively.
• The general population exposure assessment considers people living at certain distances from an
occupational asbestos release activity. Lifetime cancer risk values, ELCR, are in the range of
2.2xl0~u to 8.6xlO~4 Non-cancer chronic, MOE, risk estimates range from 12 to 2.7xlOu.
3890 5.3.1 Risk Characterization Approach
3891 The use scenarios, populations of interest and toxicological endpoints used for lifetime and chronic
3892 exposures are presented in Table 5-1.
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Table 5-20. Use Scenarios,
'opulations of Interest and Toxicological Endpoints Used for Acute and Chronic Exposures
Workers
Chronic and Lifetime - Adolescent (>16 vears old) and adult workers exposed to asbestos for the entire 8-hr workday for lid to 250
days per year for 40 working years
Occupational non-users
Chronic and Lifetime - Adolescent (>16 vears old) and adult workers exposed to asbestos for the entire 84ir workday for lid to 250
days per year for 40 working years
Population of Interest and
Exposure Scenario
Take-Home Garment Handlers
Chronic and Lifetime - Adolescent (>16 vears old) and adults exposed to asbestos durine handline of clothine contaminated with
asbestos from occupational activities, for 40 working years
Consumers
Lifetime and Chronic - Adolescent (>16 vears old) and adult DIYers exposed to asbestos fibers for a Ions oeriod of time durine an
activity
General Population
Lifetime and Chronic - All senders and ase erouos indoor enviromnents exposed to asbestos fibers infiltrating from outside from
occupational exposure activities and disposal releases
Bystanders
Lifetime and Chronic - Individuals of all ases exposed to asbestos fibers through DIYers and take-home activities.
Health Effects, Concentration
and Time Duration
Non-cancer Hazard Value
POD: The POD derived from epidemiologic data represents a 24-hour value and exposure concentrations have been adjusted to match
the time duration for inhalation exposure.
2.6E-02 fiber/cc
Most sensitive and robust non-cancer health effects"
Chronic - Localized pleural thickening of pleura in humans based on epidemiologic data from an occupational cohort (see Section 5.2.1)
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Uncertainty Factors (UF) and
Risk Estimate Calculations
BenchmarkMOE = 300 for the most sensitive and robust endpoint
Benchmark MOE = (UFS) x (UFH) x (UFD)h 10/10x3
Equation 5-2. Equation to Calculate Non-cancer Risks
Non - cancer Hazard value (POD)
MOEchronic Human Exposure
Where:
MOE = margin of exposure (unitless)
Hazard value (POD) = POD (f/cc)
Human Exposure = Exposure estimate (f/cc) from occupational (see Appendix E), take-home (see Section 5.1.2), consumer (see
Section 5.1.3), and general population (see Section 5.1.40)
Cancer Hazard Value
IUR: The inhalation unit risk value derived from epidemiologic data represents the upper-bound excess lifetime cancer risk estimated
to result from continuous exposure (per fiber/cc). For asbestos, the underlying epidemiologic data accounts for exposure to a range of
fibers and for cancers including mesothelioma, lung, laryngeal, and ovarian.
Equation 5-3. Equation to Calculate Lifetime Cancer Risk
ELCR = EPC X TWF X IURLTL or Lifetime
Where:
ELCR = Excess Lifetime Cancer Risk, the risk of developing cancer as a consequence of the site-related exposure
EPC = Exposure Point Concentration, the concentration of asbestos fibers in air (f/cc) for the specific activity being assessed
IUR ltl or Lifetime = Inlialation Unit Risk per (f/cc) Less than Lifetime or Lifetime
TWF = Time Weighting Factor, this factor accounts for less-than-continuous exposure during a 1-year exposure
" Exposures earlier in life result in greater risk, as time since first exposure is a strong predictor of effect.
h UFS= subchronic to chronic UF; UFH= intraspecies UF; UFD= database
3894
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Non-cancer risks from exposure in occupational settings are assessed by first calculating the MOE using
Equation 5-2, where human exposure is defined by the average daily concentration (ADC). The
calculated MOE is then compared to the benchmark MOE. If the numerical value of the MOE is less
than the benchmark MOE, this is a starting point to determine if there are unreasonable non-
cancer risks. Chronic cancer risks from exposure in occupational settings are assessed by calculating
the Excess Lifetime Cancer Risk (ELCR) using Equation 5-3, where the exposure point concentration is
equal to the 8-hour TWA concentration for the occupational use. The calculated ELCR is then compared
to the benchmark ELCR. If the calculated ELCR is greater than the benchmark ELCR, this is a
starting point to determine if there are unreasonable cancer risks.
Inhalation non-cancer and lifetime-cancer risk estimates from take-home exposures are calculated using
yearly average concentrations summarize in Section 5.1.2 with the specific considerations of POD
(MOE) and IUR (ELCR) values. Consumer DIY inhalation non-cancer and lifetime-cancer risk
estimates are calculated using the scenario specific exposure point concentration and exposure duration
parameters described in Section 5.1.3.1 and using Equation 5-2 and Equation 5-3. Similarly, general
population inhalation non-cancer and lifetime-cancer risk estimates are calculated using releases of
asbestos to ambient air and unique scenario exposure durations summarized in Section 5.1.40 and using
Equation 5-2 and Equation 5-3 to obtain MOE and ELCR estimates.
5.3.2 Summary of Human Health Risk Characterization
5.3.2.1 Summary of Risk Estimates for Workers
This section presents a summary of occupational risk characterization for each occupational exposure
scenario (OES), and Table 5-21 summarizes the risk estimates for inhalation exposures for all OESs.
The crosswalk between OESs and COUs can be found in Table 3-1, and EPA expects that the data
within an OES are representative of all COU subcategories mapped to the OES. The occupational
exposure assessment is presented in Section 5.1.1, and all uncertainties and assumptions associated with
the occupational exposure assessment are described in Section 5.1.1.4.1. It is important to note that all
occupational inhalation exposures are based on monitoring data. With exception of two OES (i.e.,
handling of vermiculite-containing products and mining of non-asbestos commodities), all occupational
exposure estimations are quantitative analyses. The basis in the development of occupational exposure
scenarios for this risk evaluation is that friable asbestos are modified (e.g., removed, sanded, cut,
disturbed) to release fibers. An asbestos containing product that stays in place without any modification
done to it, is not expected to result in releases, and hence no human exposures and risks are expected.
Monitoring data was collected from OSHA's Chemical Exposure Health Data (CEHD) database. This
data was mapped using SIC codes without specific information on worker activities. As a result, there is
some uncertainty in the mapping of OSHA CEHD data to similar exposure groups under each OES.
Current federal regulations mitigate asbestos exposure through actions such as exposure limits for
workers (OSHA), bans of certain asbestos materials or garments (CPSA and FHSA), and protections for
schools (AHERA). The mitigations utilized during area and personal sampling underlying the exposure
estimates for this assessment varied and were not always reported. Additionally, EPA recognizes that
guidelines may not always be followed due to lack of knowledge regarding asbestos identification,
removal, handling, and disposal, as well as personal choice. To account for these uncertainties, the
exposure scenarios in this risk evaluation did not assume compliance with existing federal regulations.
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Handling Asbestos-Containing Building Materials During Maintenance, Renovation, and Demolition
Activities
For chronic non-cancer inhalation exposures, high-end MOE values ranged from 1.3 to 12 and central
tendency MOE values ranged from 43 to 514. For chronic cancer inhalation exposures, high-end ELCR
values ranged from 2.Ox 10~5 to 1,9x 10~4 and central tendency ELCR values ranged from 4.9x 10~7 to
5.8xl0~6.
There was a 2 orders of magnitude variation in the values of the central tendency and high-end risk
estimates for two of the three Similar Exposure Groups (SEGs) assessed in this OES. These differences
are explained below for each SEG:
• Higher Exposure-Potential Workers: There was a large amount of data for workers in this SEG
(847 monitoring data points). The central tendency exposure value for this group was 0.001 f/cc,
while the high-end value was 0.429 f/cc. Workers in this SEG included asbestos removal
workers, insulation workers, demolition workers, and maintenance personnel. A total of 467 data
points for this SEG were found in OSHA's CEHD database, and 317 of these data points were
non-detects. For these samples, EPA estimated potential asbestos concentrations using the LOD
of 2,117.5 fibers/sample based on NIOSH Method 7400. The samples evaluated with this method
averaged concentrations around 0.001 f/cc for 8-hr TWAs. This large group of non-detects and
zero asbestos concentration samples resulted in a large deviation between the central tendency
and high-end results for this SEG.
• Lower Exposure-Potential Workers: There were only 31 monitoring datapoints included for the
workers in this SEG. The central tendency exposure value for this group was 0.001 f/cc, while
the high-end value was 0.219 f/cc. Similar to the SEG for Higher Exposure-Potential Workers, a
majority of the samples came from OSHA's CEHD database. All 17 samples were non-detects.
For these samples, EPA again estimated potential asbestos concentrations using the LOD of
2,117.5 fibers/sample based on NIOSH Method 7400. The samples evaluated with this method
averaged concentrations around 0.001 f/cc for 8-hr TWAs. This large group of non-detects and
zero asbestos concentration samples resulted in a large deviation between the central tendency
and high-end results for this SEG.
• Occupational Non-users: There was a smaller variation in the exposure data for this SEG; the
central tendency exposure value for this group was 0.012 f/cc, while the high-end (maximum)
value was 0.05 f/cc. There were a total of 103 datapoints for this group, 100 of which came from
one source that only provided the arithmetic mean of the data. This lack of data resulted in a
small range between the central tendency and high-end exposure estimates.
It is important to note that worker responsibilities may vary on a daily basis, and a worker may be
involved with either higher exposure potential or lower exposure potential activities as needed by the
specific project. It is also pertinent to note that the large number of non-detect exposure values for
higher and lower exposure potential workers may have led to artificially reduced inhalation exposure
values of central tendency for workers. Because workers may shift responsibilities as needed, and
because of the large number of non-detect exposure values that may have led to reduced central
tendency estimates for workers, EPA assumes that risk to workers involved with demolition,
maintenance, and renovation of structures containing asbestos is most reflected by the high-end of the
higher exposure potential worker group.
Regarding ONU risk characterization, ONUs assessed for this OES had higher central tendency chronic
(non-cancer) inhalation exposures and ELCR values than worker estimates (ELCR values were 6.7x 10~5
for ONUs and 6.1 x 10~6 for workers). This is due to a lack of data sources for ONU inhalation
monitoring data. Exposure estimates for ONUs were based on a total of 103 data points, 100 of which
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4001
4002
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came from a single source (Bailey et al.. 1988) while another source provided the remaining 3 (Boelter
et al.. 2016). The first source did not provide the raw data, but gave the mean for the data of 0.04 f/cc.
Boelter et al. provided samples of 0.0008, 0.017, and 0.046 f/cc. Because Bailey etcil. (1988) only
provided the mean value of exposure data, it was not possible to determine an accurate value of central
tendency (i.e., 50th percentile) from the overall pool of data for the OES. However, based on the
available data for the OES described above, it can be confidently stated that the highest measured
concentration of asbestos was 0.046 f/cc from Boeder et al. (2016). The high-end data point was
captured using reliable monitoring methods and is also consistent with the data collected by Bailey et al.
(1988). Therefore, EPA assumes that risk to ONUs involved with demolition, maintenance, and
renovation of structures containing asbestos is most reflected by the high-end of the ONU exposure data.
Handling Asbestos-Containing Building Materials During Firefighting or Other Disaster Response
Activities
For chronic non-cancer inhalation exposures, high-end MOE values ranged from 25 to 74 and central
tendency MOE values ranged from 475 to 1424. For chronic cancer inhalation exposures, high-end
ELCR values ranged from 3.4xl0~6 to 1.0/10 5 and central tendency ELCR values ranged from
1.8xl0~7 to 5.3xlO~7
There was an order of magnitude difference in the values for the central tendency and high-end exposure
estimates for the workers assessed in this OES. There were 62 monitoring data points for the workers in
this OES. The central tendency exposure value for this group was 0.02 f/cc, while the high-end value
was 0.39 f/cc. Activities for the workers in this OES included truck and heavy equipment operation,
general labor, and cleanup after fires, earthquakes, and other disasters (including 9/11 cleanup). The
monitoring data collected for these activities varied, with datapoints for 9/11 debris and fire cleanup
having the highest asbestos concentrations of 0.54 and 0.4 f/cc respectively. The low value for the
central tendency exposure estimate was primarily a result of 24 non-detect datapoints, 22 of which were
taken from a study where workers were assisting in the cleanup effort from a fire (Lewis and Curtis.
1990). The asbestos concentrations in the samples were conservatively estimated as half of the author
provided LOD for the sampling method in the study. The samples evaluated with this method had
calculated concentrations between 0.003 to 0.005 f/cc for 8-hr TWAs. This group of non-detects and
zero asbestos concentration samples resulted in a large deviation between the central tendency and high-
end results for this OES. Because of the large number of non-detect exposure values that may have led
to reduced central tendency estimates for workers, EPA assumes that risk to workers involved with
firefighting and disaster response activities is most reflected by the high-end of the worker group.
Use, Repair, or Removal of Industrial and Commercial Appliances or Machinery Containing
Asbestos
For chronic non-cancer inhalation exposures, high-end MOE values ranged from 0.72 to 2.3 and central
tendency MOE values ranged from 4.1 to 14. For chronic cancer inhalation exposures, high-end ELCR
values ranged from 1.1 x 10~4 to 3.5 x 10~4 and central tendency ELCR values ranged from 1.9x 10~5 to
6.1xl0~5.
There were two orders of magnitude differences in the values of the central tendency and high-end risk
estimates for the two SEGs assessed in this OES. These differences are explained below for each SEG:
• Workers: There were a total of 216 monitoring data points for workers in this SEG. The central
tendency exposure value for this group was 0.008 f/cc, while the high-end value was 0.157 f/cc.
Workers in this SEG included heavy machinery workers, mechanics, and engine workers, while
worker activities ranged from engine repair to working with asbestos insulation on furnaces.
These activities varied in their potential for worker exposure to asbestos, and likely contributed
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to the difference between the central tendency and high-end exposure estimates. Another
contributor may have been the considerable number of samples that were sourced from a study
conducted by Mlynarek and Van Orden at one site where workers we reperforming maintenance
on an airplane engine (Mlynarek and Van Orden. 2012). This study provided 114 monitoring
datapoints for workers in this OES that averaged asbestos concentrations of 0.006 f/cc, which
lowered the central tendency estimate for this SEG.
• Occupational Non-users: There was a smaller variation in the exposure data for this SEG; the
central tendency exposure value for this group was 0.028 f/cc, while the high-end (maximum)
value was 0.049 f/cc. There were a total of 20 datapoints for this group, all of which came from
the study conducted by Mlynarek & Orden (Mlynarek and Van Orden. 2012). This lack of data
resulted in a small range between the central tendency and high-end exposure estimates.
PBZ monitoring data used to estimate worker exposure showed high-end and central tendency exposure
levels that exceeded the benchmark MOE for the chronic (non-cancer) endpoint, as well as high-end
chronic (cancer) exposure levels that exceeded the benchmark ELCR. Because the analysis contained
114 monitoring datapoints for workers in this OES that averaged asbestos concentrations of 0.006 f/cc,
artificially lowering the central tendency estimate for this SEG, EPA assumes that risk to workers
involved with use, repair, and removal of machinery or appliances containing asbestos is most reflected
by the high-end of the worker group.
ONUs assessed for this OES had higher central tendency chronic (non-cancer) inhalation exposures and
ELCR values than worker estimates (ELCR values were 7.6 x 1CT4 for ONUs and 2.3 x ] 0 4 for workers).
This is due to a lack of data sources for ONU inhalation monitoring data. Exposure estimates for ONUs
were all collected from the study conducted by Mlynarek & Orden (2012). The source did not provide
the raw data but gave two mean values taken from two groups of ten samples that were taken from
bystanders in the workshop while workers were performing a high-risk activity
(disassembling/reassembling an aircraft engine). Due to the lack of information regarding the full
distribution of exposure data, it was not possible to determine an accurate value of central tendency (i.e.,
50th percentile) from the overall pool of data for the OES. Because the true distribution of data is not
certain from the available data, EPA assumes that the risk to ONUs involved with use, repair, and
removal of machinery is most reflected by the larger of the two mean values from Mlynarek & Orden
(2012) which is associated with high-end ONU exposure for the OES.
Handling Articles or Formulations that Contain Asbestos
For chronic non-cancer inhalation exposures, high-end MOE values ranged from 0.16 to 99 and central
tendency MOE values ranged from 1.1 to 105. For chronic cancer inhalation exposures, high-end ELCR
values ranged from 2.5><10~6 to 1.5/10 3 and central tendency ELCR values ranged from 2.4/ 10 6 to
2.2xlO~4
There was an order of magnitude variation in the values of the central tendency and high-end risk
estimates for one of the three SEGs assessed in this OES. These differences are explained below for
each SEG:
• Higher Exposure-Potential Workers: There were a total of 46 monitoring data points for workers
in this SEG. The central tendency exposure value for this group was 0.1 f/cc, while the high-end
value was 0.69 f/cc. Worker activities for this SEG included working with asbestos-containing
plastics, sanding asbestos-containing joint compounds, and processing/using asbestos-containing
coatings, adhesives, and sealants. A total of 6 data points for this SEG were found in OSHA's
CEHD database, all of which were zero values or non-detects. For these samples, EPA estimated
potential asbestos concentrations using the LOD of 2,117.5 fibers/sample based on NIOSH
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Method 7400. The samples evaluated with this method averaged concentrations around 0.001
f/cc for 8-hr TWAs. There was also a group of 13 datapoints for workers handling asbestos-
containing window caulking that had a maximum 8-hr TWA value of 0.05 f/cc; further lowering
the central tendency value. In addition, one study for pole sanding of asbestos-containing joint
compound provided samples with high levels of asbestos concentrations (Brorbv et al.. 2013).
Two groups of samples from this study averaged 8-hr TWAs of 0.99 f/cc (6 samples) and 0.62
f/cc (5 samples); raising the estimate for high-end exposure for this SEG. These groups of non-
detects and low asbestos concentration samples combined with the groups of high concentration
samples resulted in a deviation between the central tendency and high-end results for this SEG.
• Lower Exposure-Potential Workers: There were only seven monitoring datapoints included for
the workers in this SEG. The central tendency exposure value for this group was 0.008 f/cc,
while the high-end value was 0.011 f/cc. One non-detect sample came from OSHA's CEHD
database. EPA again estimated potential asbestos concentrations using the LOD of 2,117.5
fibers/sample based on NIOSH Method 7400. The sample evaluated with this method had a
concentration around 0.001 f/cc for an 8-hr TWA. The remaining samples were taken from one
study that sampled laboratory workers (8-hr TWAs were between 0.009-0.012 f/cc).
• Occupational Non-users: There was a smaller variation in the exposure data for this SEG; the
central tendency exposure value for this group was 0.0011 f/cc, while the high-end value was
0.0012 f/cc. There were a total of 7 datapoints for this group, all of which were non-detect
samples taken from OSHA's CEHD database. This lack of data resulted in a small range between
the central tendency and high-end exposure estimates.
Waste Handling, Disposal, and Treatment
For chronic non-cancer inhalation exposures, the high-end MOE value for workers was 3.6 and the
central tendency MOE value for workers was 77. For chronic cancer inhalation exposures, the high-end
ELCR value for workers was 7.Ox 10~5 and the central tendency ELCR value for workers was 3,2/ 10 6,
There were no ONU data available for this OES, therefore, central tendency worker estimates were
applied as an approximation of likely ONU exposures.
There was a significant difference in the values for the central tendency and high-end exposure estimates
for the workers assessed in this OES. There were 95 monitoring data points for the workers in this OES.
The central tendency exposure value for this group was 0.001 f/cc, while the high-end value was 0.032
f/cc. A total of 36 data points for this SEG were found in OSHA's CEHD database, and 35 of these data
points were non-detects. For these samples, EPA estimated potential asbestos concentrations using the
LOD of 2,117.5 fibers/sample based on NIOSH Method 7400. The samples evaluated with this method
averaged concentrations around 0.001 f/cc for 8-hr TWAs. This large group of non-detects and zero
asbestos concentration samples resulted in a large deviation between the central tendency and high-end
results for this SEG. Because of the large number of non-detect exposure values that may have led to
reduced central tendency estimates for workers, EPA assumes that risk to workers involved with
disposal of asbestos-containing materials is most reflected by the high-end of the worker group.
Handling of Vermiculite-Containing Products for Agricultural and Laboratory Purposes
Qualitative assessment of vermiculite-containing products for agricultural and laboratory use indicates
that risk of asbestos exposure is not expected during occupational use. See Appendix E.14 for more
details.
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4127 Mining of Non-asbestos Commodities
4128 Qualitative assessment of asbestos exposure during the mining of non-asbestos commodities indicates
4129 that risk of asbestos exposure is not expected during occupational use. See Appendix E.15 for more
4130 details.
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Table 5-21.
Occupational Risk Estimat
es Summary
Life Cycle
Stage/
Category
Subcategory
OES
Endpoint
Benchmark
MOE or
ELCR"
Population*
Exposure
Route and
Durationc
Exposure
Level
Inhalation
Monitoring:
No PPE
Worker MOE
or ELCR"
Inhalation
Monitoring:
APF = 10
Worker MOE
or ELCR"
Inhalation
Monitoring:
APF = 50
Worker MOE
or ELCR"
Industrial/
Commercial
Uses
Construction
and building
materials
covering large
surface areas,
including
paper articles;
metal articles;
stone, plaster,
cement, glass,
and ceramic
articles
Construction
and building
materials
covering large
surface areas,
including
fabrics,
textiles, and
apparel
Handling
asbestos-
containing
building
materials
during
maintenance,
renovation, and
demolition
activities
Chronic non-
cancer
300
Higher
Exposure-
Potential
Worker
Inhalation
8-hr TWA
High-
End
1.3
13
66
Central
Tendencv
514
5,137
2.6E04
Lower
Exposure-
Potential
Worker
High-
End
2.6
26
130
Central
Tendencv
509
5,092
2.5E4
ONU
High-
End
12
-
-
Central
Tendencv
46
-
-
Handling
asbestos-
containing
building
materials
during
maintenance,
renovation, and
demolition
activities
Cancer
1E-4
Higher
Exposure-
Potential
Worker
Inhalation
8-hr TWA
High-
End
1.9E-04
1.9E-05
3.8E-06
Central
Tendencv
4.9E-07
4.9E-08
9.7E-09
Lower
Exposure-
Potential
Worker
Inhalation
8-hr TWA
High-
End
9.6E-05
9.6E-06
1.9E-06
Central
Tendencv
4.9E-07
4.9E-08
9.8E-09
ONU
Inhalation
8-hr TWA
High-
End
2.0E-05
-
-
Central
Tendencv
5.4E-06
-
-
Industrial/
Commercial
Uses
Construction
and building
materials
covering large
surface areas,
including
paper articles;
metal articles;
stone, plaster,
cement, glass,
and ceramic
articles;
Handling
asbestos-
containing
building
materials
during
maintenance,
renovation, and
demolition
activities
Chronic non-
cancer
300
Higher
Exposure-
Potential
Worker
Inhalation
Short-Term
High-
End
1.4
14
69
Central
Tendencv
219
2,191
1.1E4
Lower
Exposure-
Potential
Worker
Inhalation
Short-Term
High-
End
2.7
28
137
Central
Tendencv
218
2,183
1.1E4
ONU
Inhalation
Short-Term
High-
End
12
-
-
Central
Tendency
43
—
—
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Inhalation
Inhalation
Inhalation
Life Cycle
Stage/
Category
Subcategory
OES
Endpoint
Benchmark
MOE or
ELCR"
Population*
Exposure
Route and
Durationc
Exposure
Level
Monitoring:
No PPE
Worker MOE
or ELCR"
Monitoring:
APF = 10
Worker MOE
or ELCR"
Monitoring:
APF = 50
Worker MOE
or ELCR"
Higher
High-
1.8E-04
1.8E-05
3.61E-06
Construction
Handling
asbestos-
Exposure-
Inhalation
End
and building
Potential
Short-Term
Central
1.1E-06
1.1E-07
2.3E-08
materials
containing
building
Worker
Tendency
covering large
Lower
High-
9.1E-05
9.1E-06
1.8E-06
surface areas.
materials
Cancer
1E-4
Exposure-
Inhalation
End
including
during
Potential
Short-Term
Central
1.1E-06
1.1E-07
2.3E-08
fabrics.
maintenance.
Worker
Tendency
textiles, and
apparel
renovation, and
demolition
ONU
Inhalation
High-
End
2.0E-05
-
-
activities
Short-Term
Central
Tendency
5.8E-06
—
—
Construction
Handling
High-
25
246
1,231
and building
asbestos-
Firefighters
Inhalation
End
materials
containing
(Career)
8-hr TWA
Central
475
4,745
2.4E4
covering large
building
Tendency
surface areas.
materials
Chronic non-
300
High-
74
739
3,693
including
during
cancer
End
paper articles;
metal articles;
stone, plaster.
firefighting or
other disaster
response
Firefighters
(Volunteer)
Inhalation
8-hr TWA
Central
Tendency
1424
1.4E4
7.1E4
Industrial/
Commercial
Uses
cement, glass.
activities
and ceramic
High-
1.0E-5
1.0E-6
2.0E-7
articles;
Handling
Firefighters
Inhalation
End
Construction
asbestos-
containing
(Career)
8-hr TWA
Central
Tendency
5.3E-7
5.3E-8
1.1E-8
and building
materials
building
materials
Cancer
1E-4
High-
End
34E-6
3.4E-7
6.8E-8
covering large
surface areas,
including
fabrics,
textiles, and
during
firefighting or
other disaster
response
activities
Firefighters
(Volunteer)
Inhalation
8-hr TWA
Central
Tendency
1.8E-7
1.8E-8
3.5E-9
apparel
Machinery,
mechanical
Use, repair, or
removal of
Chronic non-
cancer
300
Worker
Inhalation
8-hr TWA
High-
End
0.73
7.3
36
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PUBLIC RELEASE DRAFT
April 2024
Life Cycle
Stage/
Category
Subcategory
OES
Endpoint
Benchmark
MOE or
ELCR"
Population*
Exposure
Route and
Durationc
Exposure
Level
Inhalation
Monitoring:
No PPE
Worker MOE
or ELCR"
Inhalation
Monitoring:
APF = 10
Worker MOE
or ELCR"
Inhalation
Monitoring:
APF = 50
Worker MOE
or ELCR"
Industrial/
Commercial
Uses
appliances,
electrical/elect
ronic articles
Other
machinery,
mechanical
appliances,
electronic/elec
tronic articles
industrial and
commercial
appliances or
machinery
containing
asbestos
Central
Tendency
14
135
674
ONU
Inhalation
8-hr TWA
High-
End
2.3
-
-
Central
Tendency
4.1
—
—
Use, repair, or
removal of
industrial and
commercial
appliances or
machinery
containing
asbestos
Cancer
1E-4
Worker
Inhalation
8-hr TWA
High-
End
3.4E-I
3.4E-5
6.9E-6
Central
Tendency
1.9E-5
1.9E-6
3.7E-7
ONU
Inhalation
8-hr TWA
High-
End
1.1E-I
-
-
Central
Tendency
6.1E-5
—
—
Industrial/
Commercial
Uses
Machinery,
mechanical
appliances,
electrical/elect
ronic articles
Other
machinery,
mechanical
appliances,
electronic/elec
tronic articles
Use, repair, or
removal of
industrial and
commercial
appliances or
machinery
containing
asbestos
Chronic non-
cancer
300
Worker
Inhalation
Short-Term
High-
End
0.72
7.2
36
Central
Tendency
13
125
625
ONU
Inhalation
Short-Term
High-
End
No Data
No Data
No Data
Central
Tendency
No Data
No Data
No Data
Use, repair, or
removal of
industrial and
commercial
appliances or
machinery
containing
asbestos
Cancer
1E-4
Worker
Inhalation
Short-Term
High-
End
3.5E-04
3.5E-05
6.9E-06
Central
Tendency
2.0E-05
2.0E-06
4.0E-07
ONU
Inhalation
Short-Term
High-
End
No Data
No Data
No Data
Central
Tendency
No Data
No Data
No Data
Industrial/
Commercial
Uses
Electrical
batteries and
accumulators
Solvent-
based/water-
based paint
Handling
articles or
formulations
that contain
asbestos
Chronic non-
cancer
300
Higher
Exposure-
Potential
Worker
Inhalation
8-hr TWA
High-
End
0.16
1.6
8.2
Central
Tendency
1.1
11
57
Lower
Exposure-
Inhalation
8-hr TWA
High-
End
10
103
513
Page 164 of 405
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PUBLIC RELEASE DRAFT
April 2024
Inhalation
Inhalation
Inhalation
Life Cycle
Stage/
Category
Subcategory
OES
Endpoint
Benchmark
MOE or
ELCR"
Population*
Exposure
Route and
Durationc
Exposure
Level
Monitoring:
No PPE
Worker MOE
or ELCR"
Monitoring:
APF = 10
Worker MOE
or ELCR"
Monitoring:
APF = 50
Worker MOE
or ELCR"
Fillers and
Potential
Central
14
138
690
putties
Worker
Tendency
Furniture &
High-
99
-
-
furnishings
ONU
Inhalation
End
including
8-hr TWA
Central
103
-
-
stone, plaster,
cement, glass,
and ceramic
articles; metal
articles; or
rubber articles
Packaging
(excluding
food
Tendency
Higher
Exposure-
Inhalation
High-
End
1.5E-3
1.5E-4
3.0E-5
Potential
Worker
8-hr TWA
Central
Tendency
2.2E-1
2.2E-5
4.4E-6
Lower
Exposure-
Inhalation
High-
End
24E-5
2.4E-6
4.9E-7
Potential
8-hr TWA
Central
1.8E-5
1.8E-6
3.6E-7
packaging).
Worker
Tendency
including
rubber
High-
End
2.5E-6
-
-
articles;
plastic articles
(hard); plastic
articles (soft)
Toys intended
for children's
use (and child
dedicated
Handling
articles or
formulations
that contain
asbestos
Cancer
1E-4
Central
Tendency
24E-6
articles),
including
fabrics.
ONU
Inhalation
8-hr TWA
textiles, and
apparel; or
plastic articles
(hard)
Other
(artifacts)
Other
(aerospace
applications)
Page 165 of 405
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PUBLIC RELEASE DRAFT
April 2024
Inhalation
Inhalation
Inhalation
Life Cycle
Stage/
Category
Subcategory
OES
Endpoint
Benchmark
MOE or
ELCR"
Population*
Exposure
Route and
Durationc
Exposure
Level
Monitoring:
No PPE
Worker MOE
or ELCR"
Monitoring:
APF = 10
Worker MOE
or ELCR"
Monitoring:
APF = 50
Worker MOE
or ELCR"
Electrical
Higher
High-
0.17
1.7
8.7
batteries and
Exposure-
Inhalation
End
accumulators
Potential
Short-Term
Central
1.2
12
58
Solvent-
Handling
articles or
formulations
that contain
asbestos
Worker
Tendency
based/water-
Lower
High-
8.7
87
436
based paint
Chronic Non-
300
Exposure-
Inhalation
End
Fillers and
putties
cancer
Potential
Worker
Short-Term
Central
Tendency
13
126
632
Furniture &
furnishings
ONU
Inhalation
High-
End
97
965
4,825
including
stone, plaster,
cement, glass,
and ceramic
articles; metal
articles; or
rubber articles
Packaging
(excluding
food
packaging),
including
rubber
articles;
plastic articles
(hard); plastic
articles (soft)
Toys intended
Short-Term
Central
Tendency
105
1,048
5,238
Higher
Exposure-
Inhalation
High-
End
1.4E-3
1.4E-4
2.9E-5
Potential
Worker
Short-Term
Central
Tendency
2.2E-1
2.2E-5
4.3E-6
Industrial/
Lower
Exposure-
Inhalation
High-
End
2.9E-5
2.9E-6
5.7E-7
Commercial
Potential
Short-Term
Central
2.0E-5
2.0E-6
4.0E-7
Uses
Worker
Tendency
High-
End
2.6E-6
2.6E-7
5.2E-8
Handling
articles or
formulations
that contain
asbestos
Cancer
1E-4
Central
Tendency
2.4E-6
2.4E-7
4.8E-8
for children's
use (and child
dedicated
ONU
Inhalation
Short-Term
articles),
including
fabrics.
textiles, and
apparel; or
plastic articles
(hard)
Page 166 of 405
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PUBLIC RELEASE DRAFT
April 2024
Inhalation
Inhalation
Inhalation
Life Cycle
Stage/
Category
Subcategory
OES
Endpoint
Benchmark
MOE or
ELCR"
Population*
Exposure
Route and
Durationc
Exposure
Level
Monitoring:
No PPE
Worker MOE
or ELCR"
Monitoring:
APF = 10
Worker MOE
or ELCR"
Monitoring:
APF = 50
Worker MOE
or ELCR"
Other
(artifacts)
Other
(aerospace
applications)
Waste
High-
3.6
36
180
handling.
Chronic Non-
300
Worker
Inhalation
End
Disposal,
Disposal,
disposal, and
cancer
8-hr TWA
Central
77
774
3,872
including
including
treatment
Tendency
Distribution
Distribution
Waste
High-
7.0E-5
7.0E-6
1.4E-6
for Disposal
for Disposal
handling.
Cancer
1E-4
Worker
Inhalation
End
disposal, and
8-hr TWA
Central
3.2E-6
3.2E-7
6.5E-8
treatment
Tendency
" For chronic non-cancer endpoints, the benchmark MOE is compared to the estimated MOE values calculated from inhalation monitoring data. For chronic cancer
endpoints, the benclunark ELCR is compared to the estimated ELCR values calculated from inhalation monitoring data.
h EPA is unable to estimate ONU exposures separately from workers; central tendency worker estimates were applied as an approximation of likely ONU exposures.
c Short-term risk estimates use 30 minute exposure concentrations averaged with 7.5 hours at the full shift exposure concentration.
4132
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4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
PUBLIC RELEASE DRAFT
April 2024
5.3.2.2 Summary of Risk Estimates for Take-Home Exposures
Table 5-22 summarizes the risk estimates for take-home exposures for lifetime cancer and non-cancer
chronic inhalation exposures. The take-home exposure assessment approaches and calculations are
presented in Sections 3.1.2 and 5.1.2. The take-home exposure assessment considers handler and
bystander, that are exposed to asbestos contaminated clothing during garment handling (e.i., laundry,
shaking of garment, undressing and dressing, folding). The source of the asbestos contamination are
activities related to occupational scenarios, hence the link to the occupational exposure COUs and
scenarios. In addition, this take-home exposure assessment considers people, bystander, in proximity or
within the same room as the person handling the contaminated garment. All of the take-home exposure
scenarios considered people 16 years of age and older for all genders for garment handler for less-than-
lifetime exposure scenarios and 78 years for lifetime cancer risk estimates. Bystanders were considered
in three lifestages, 0 to 20 years to represent children living at home (where the take-home exposure
occurs) and then moving away at 20 years of age, shown in Table 5-22. Other bystander populations
considered are people living in the same household as the take-home exposure occurs for the duration of
the exposure, 40 years, risk estimates shown in 6.4.1J.3. Additional bystander scenarios considered all
ages and genders, lifetime exposure for bystanders, representing people starting the exposure at birth and
throughout their entire life, whether they live in the same households or other in which take-home
exposures occur and they are bystanders to the handling of asbestos contaminated clothing, shown in
6.4.1J.3. This lifetime exposure duration is 78 years total, which is equal to the life expectancy.
Of note, the risk summary below is based on the most sensitive non-cancer endpoint for all relevant
duration scenarios, as well as cancer. For the majority of exposure scenarios, risks were identified for
multiple endpoints in lifetime cancer exposure scenarios.
For chronic non-cancer inhalation exposures the risks values for garment handlers and bystanders for
high-intensity exposure levels for all COUs except firefighting related activities range from 11 to 236.
While central tendency risk values range from 672 to 8.4><105 (840,437) for handler and bystander. The
wide range between HE and CT risk values is due to, (1) one order of magnitude difference between the
slope in the regression analysis used to calculate HE and CT exposure concentrations, and (2) the
occupational exposure concentration (see Section 5.3.2.1) used to estimate garment asbestos
contamination concentrations.
For lifetime cancer inhalation exposures the risk values for both garment handlers and bystanders for
high-intensity exposure levels for all COUs except for volunteer firefighting and other disaster response
activities range from 2.5x ] 0 6 to 3.7/10 4. Central-tendency inhalation lifetime cancer risk values for
handler and bystander range from 3.1 x 10~9 to 6.Ox 10~6. The wide range between HE and CT risk values
is due to, (1) one order of magnitude difference between the slope in the regression analysis used to
calculate HE and CT exposure concentrations, and (2) the occupational exposure concentration (see
Section 5.3.2.1) used to estimate garment asbestos contamination concentrations.
Page 168 of 405
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PUBLIC RELEASE DRAFT
April 2024
Table 5-22. Take-Home Inhalation Ris
i. Estimates Summary
COUs
OES
Population
Age
Group
Chronic Non-cancer
(Benchmark MOE = 300)
Cancer Lifetime
(Benchmark = 1E-6)
CT
HE
CT
HE
Construction, paint, electrical, and metal
products and.
Furnishing, cleaning, treatment care products
Maintenance, renovation, and
demolition
Handler
>16 to 40°
305,613
88
1.3E-8
4.6E-5
Bystander
0 to 20*
960,756
268
1.3E-8
4.5E-5
Construction, paint, electrical, and metal
products and.
Furnishing, cleaning, treatment care products
Firefighting and other disaster
response activities (career)
Handler
>16 to 40°
280,146
1,615
1.4E-8
2.5E-6
Bystander
0 to 20*
880,693
4,919
9.2E-9
2.5E-6
Construction, paint, electrical, and metal
products and.
Furnishing, cleaning, treatment care products
Firefighting and other disaster
response activities (volunteer)
Handler
>16 to 40°
840,437
4,846
4.8E-9
8.4E-7
Bystander
0 to 20*
2,642,080
14,757
3. IE—9
8.2E-7
Construction, paint, electrical, and metal
products
Use, repair, or removal of industrial
and commercial appliances or
machinery containing asbestos
Handler
>16 to 40°
8,004
47
5. IE—7
8.6E-5
Bystander
0 to 20*
25,163
144
3.2E-7
8.5E-5
Construction, paint, electrical, and metal
products.
Furnishing, cleaning, treatment care products,
and
Packaging, paper, plastic, toys, hobby products
Handling articles or formulations that
contain asbestos (battery insulators,
burner mats, plastics, cured
coatings/adhesives/ sealants)
Handler
>16 to 40°
672
11
6.0E-6
3.7E-4
Bystander
0 to 20*
2,114
33
3.8E-6
3.6E-4
Disposal, including distribution for disposal
Waste handling, disposal, and
treatment
Handler
>16 to 40°
44,823
236
9.1E-8
1.7E-5
Bystander
0 to 20*
140,911
719
5.8E-8
1.7E-5
" Scenario representative of garment handler patterns similar to those from occupational durations which is the source of asbestos fibers into clothing.
* Scenario representative of children living at home while contaminated clothing is handled during their living at home status, 20 years.
Other bystander scenarios are available in Appendix J.3.
4173
Page 169 of 405
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4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
PUBLIC RELEASE DRAFT
April 2024
5.3.2.3 Summary of Risk Estimates for Consumers
Table 5-23 summarizes the risk estimates for DIY activity-based scenarios for lifetime cancer and non-
cancer chronic inhalation exposures. The consumer exposure assessment is presented in 5.1.3 and data
used for the assessment is presented in Section 3.1.3. The basis in the development of consumer DIY
exposure scenarios for this risk evaluation is that friable asbestos products have to be modified (e.g.,
removed, sanded, cut, disturbed) to release fibers. An asbestos containing product that stays in place
without any modification done to it is not expected to result in asbestos fiber releases, and hence no
human exposures and risks are expected.
Of note, the risk summary below is based on the most sensitive non-cancer endpoint for all relevant
duration scenarios, as well as cancer. For the majority of consumer DIY exposure scenarios, risks were
identified for multiple endpoints in lifetime cancer exposure scenarios. All DIY activities except indoor
disturbance of coatings, mastic and adhesives, and outdoor disturbance of roofing materials resulted in
high-end tendency risks. Generally, activities about removing of asbestos containing materials resulted
in risks at the low-end, central, and high-end tendencies, while disturbing the materials resulted in risks
at the high-level tendencies. Activities related to disturbance or removal of insulation, and sanding
spackle showed risk at low and high tendencies. Removal activities resulted in larger risk estimates than
disturbance activities.
For chronic non-cancer inhalation exposures there are risks for consumer DIYers and bystanders for
some exposure scenarios for all COUs at low, medium, and high-intensity user exposure levels. As
expected, there are more DIYer and bystander scenarios with risk at the high-intensity level than at the
low-intensity level. Generally, activities about removing of asbestos containing materials resulted in
risks at high-end tendencies, while disturbing the materials resulted in risks at the high-level tendencies
for activities related to disturbance or removal of insulation, and sanding spackle.
For lifetime cancer inhalation exposures there are risks for consumer DIYers and bystander for most
scenarios and all COUs at low, central, and high-intensity user exposure levels. Risk values range from
5.1 x 10~8 to 5.1 x 10~2 for various DIY scenarios, however the LE, CT, and HE risk values for specific
DIY scenarios are an order of magnitude between LE to CT, and CT to HE. The difference root from the
asbestos concentrations measured during DIY activities and exposure time and frequency values used
forLE, CT, and HE calculations, see Table 5-11.
Page 170 of 405
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PUBLIC RELEASE DRAFT
April 2024
Table 5-23. Consumer Activity-Based Do-It-Yourself Inhalation Risk Estimates Summary
Life Cycle
COU/Subcategory
DIY Activity-Based Scenario
Population
Age
Group
Chronic Non-cancer
(Benchmark MOE = 300)
Cancer Lifetime
(Benchmark = 1E-6)
LE
CT
HE
LE
CT
HE
Construction, paint,
electrical, and metal
products / construction
and building materials
covering large surface
areas: paper articles;
metal articles; stone,
plaster, cement, glass,
and ceramic articles
Outdoor, disturbance/repair (sanding
or scraping) of roofing materials
User
16 to 78
129,071
41,288
9,836
2.3E-8
7.1E-8
3.0E-7
Bystander
Oto 78
774,424
247,726
59,019
8.4E-9
2.6E-8
1.1E—7
Outdoor, removal of roofing materials
User
16 to 78
1,433
716
119
2.1E-6
4.1E-6
2.5E-5
Bystander
Oto 78
1,433
716
119
4.6E-6
9.1E-6
5.5E-5
Indoor, removal of plaster
User
16 to 78
716
179
24
4.1E-6
1.6E-5
1.2E-4
Bystander
Oto 78
1,433
716
119
4.6E-6
9.1E-6
5.5E-5
Indoor, disturbance (sliding) of ceiling
tiles
User
16 to 78
25,470
12,735
2,122
1.2E-7
2.3E-7
1.4E-6
Bystander
Oto 78
25,470
12,735
2,122
2.6E-7
5. IE—7
3.1E-6
Indoor, removal of ceiling tiles
User
16 to 78
1,433
398
63
2.1E-6
7.4E-6
4.7E-5
Bystander
Oto 78
8,596
2,388
377
7.6E-7
2.7E-6
1.7E-5
Indoor, removal of vinyl floor tiles
User
16 to 78
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Bystander
Oto 78
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Below
LOD
Indoor, disturbance/repair (cutting) of
attic insulation.
User
16 to 78
1,279
640
213
2.3E-6
4.6E-6
1.4E-5
Bystander
Oto 78
17,909
8,954
2,985
3.7E-7
7.3E-7
2.2E-6
Indoor, moving and removal (with
vacuum) of attic insulation
User
16 to 78
494
247
82
6.0E-6
1.2E-5
3.6E-5
Bystander
Oto 78
1162
581
194
5.6E-6
1.1E-5
3.4E-5
Construction, paint,
electrical, and metal
products / fillers and
putties
Indoor, disturbance (pole or hand
sanding and cleaning) of spackle
User
16 to 78
7
1
0.1
4.0E-4
4.2E-3
2.3E-2
Bystander
Oto 78
16
4
1
4.2E-4
1.8E-3
8.5E-3
Indoor, disturbance (sanding and
cleaning) of coatings, mastics, and
adhesives
User
16 to 78
458
21
4
6.4E-6
1.4E-4
8.0E-4
Bystander
Oto 78
294
57
10
2.2E-5
1.1E-4
6.5E-4
Indoor, removal of floor tile/mastic
User
16 to 78
24,916
12,458
2,388
1.2E-7
2.4E-7
1.2E-6
Bystander
Oto 78
191,025
95,512
11,939
3.4E-8
6.8E-8
5.5E-7
Indoor, removal of window caulking
User
16 to 78
1,433
716
119
2.1E-6
4.1E-6
2.5E-5
Bystander
Oto 78
1,433
716
119
4.6E-6
9.1E-6
5.5E-5
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Life Cycle
COU/Subcategory
DIY Activity-Based Scenario
Population
Age
Group
Chronic Non-cancer
(Benchmark MOE = 300)
Cancer Lifetime
(Benchmark = 1E-6)
LE
CT
HE
LE
CT
HE
Furnishing, cleaning,
treatment care products /
Furniture and
furnishings, including
stone, plaster, cement,
glass, and ceramic
articles; metal articles; or
rubber articles
Use of mittens for glass
manufacturing, (proxy for oven
mittens and potholders)
User
16 to 78
1,433
716
119
2.1E-6
4.1E-6
2.5E-5
Bystander
Oto 78
1,433
716
119
4.6E-6
9.1E-6
5.5E-5
4207
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4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
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4223
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4225
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4227
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5.3.2.4 Summary of Risk Estimates for General Population
Table 5-24 and Table 5-25 summarize the lifetime cancer and non-cancer chronic risk estimates for
inhalation exposures for general population exposure to ambient air releases from occupational
activities. The general population exposure assessment is described in Section 5.1.40. and the data used
for the dispersion model estimates is described in Section 3.3.1.2. The general population exposure
assessment considers indoor exposures for people living at certain distance from the asbestos releases.
The distances explored in this assessment all assess exposures to the general population at the following
distances: 10, 30, 60, 100, 2,500, 5,000, and 10,000 m and the area between 100 to 1,000 m. Distances
10 to 100 m are called co-located because they are exposures in proximity to the activity which is the
source of the asbestos releases. The populations assessed in the co-located distances are different for
each of the occupational activities releasing asbestos. For example, landfills tend to have fences to keep
people outside, and hence it is not expected to have general population living, recreating, or routinely
passing by within the perimeter. However, the distance from the landfill release point to the general
population outside the perimeter can vary depending on the size of the landfill. Other activities, such as
firefighting and demolitions can have people living next to the activity without a perimeter. The co-
located distances distinction is an approach to identify people with increased exposures due to their
proximity to emission sources. In addition, the asbestos releases are summarized by COU/OES fugitive
emissions. Fugitive emissions refer to area source emissions.
For chronic non-cancer inhalation exposures, the risk values for each COU across all distances range
from 12 to 2.7x 1011 for LE, CT, and HE tendencies. The wide range of risk values for a single COU is
due the differences among concentrations and the expected deposition/fall off as distances from the
source increase.
For lifetime cancer inhalation exposures, the risk values for the general population for people at various
distances from the source for high-intensity exposure levels are summarized in Table 5-24. The risk
values for each COU across all distances range from 2.2x 10~u to 8.6x 10~4 for LE, CT, and HE
tendencies. The wide range of risk values for a single COU is due the differences among concentrations
and the expected deposition/fall off as distances from the source increase.
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4237 Table 5-24. General Population Inhalation of Outside Ambient Air Lifetime Cancer Risk Estimate Summary
OES
COU(s)
Distance from the Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
Low-end tendency lifetime cancer ELCR (f/cc) (benchmark = 1E-6 to 1E-4)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution for
disposal
1.3E-4
1.7E-5
3.4E-6
9.4E-7
LIE—8
1.5E-9
5. IE—10
1.7E-10
Handling asbestos-containing
building materials during
COU: Construction, paint, electrical, and
metal products
3.0E-5
4.2E-6
7.9E-7
2.0E-7
1.6E-9
1.5E-10
6.IE—11
2.3E-11
maintenance, renovation and
demolition activities fugitive h
COU: Furnishing, cleaning, treatment care
products
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical, and
metal products
1.7E-5
1.9E-6
3.7E-7
1.1E—7
1.3E-9
1.9E-10
6.8E-11
2.2E-11
Handling articles or
formulations that contain
asbestos fugitive"
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
COU: Packaging, paper, plastic, toys,
hobby products
2.0E-5
1.4E-5
1.3E-5
1.2E-5
2.9E-8
8.6E-9
3.3E-9
1.0E-9
Central tendency lifetime cancer ELCR (benchmark = 1E-6 to 1E-4)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution for
disposal
3.0E-4
5. IE—5
1.2E-5
3.5E-6
1.2E-7
4.9E-9
1.7E-9
6.0E-10
Handling asbestos-containing
building materials during
COU: Construction, paint, electrical, and
metal products
2.2E-5
4.2E-6
9.9E-7
2.9E-7
8.7E-9
3.4E—10
1.2E-10
4.6E-11
maintenance, renovation and
demolition activities fugitive b
COU: Furnishing, cleaning, treatment care
products
Use, repair, or disposal of
industrial and commercial
COU: Construction, paint, electrical, and
metal products
14E-5
2.2E-6
4.9E-7
1.5E-7
5.2E-9
2.3E-10
8.3E-11
2.9E-11
appliances or machinery
containing asbestos fugitive h
Handling articles or
formulations that contain
asbestos fugitive"
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
3.0E-5
1.6E-5
1.3E-5
1.3E-5
3.3E-7
1.8E-8
7.6E-9
2.7E-9
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OES
COU(s)
Distance from the Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
COU: Packaging, paper, plastic, toys,
hobby products
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive b
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
2.8E-8
7.0E-9
2.0E-9
6.6E-10
2.2E-11
6.8E-13
2.0E-13
7.5E-14
High-end tendency lifetime cancer ELCR (f/cc) (benchmark = 1E-6 to 1E-4)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution for
disposal
8.6E-4
1.8E-4
4.4E-5
1.4E-5
6.0E-7
1.6E-8
5.5E-9
2.0E-9
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive h
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
6.3E-5
1.3E-5
3.2E-6
9.8E-7
5.8E-8
1.2E-9
4.0E-10
1.5E-10
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical, and
metal products
1.3E-4
2.7E-5
6.8E-6
2. IE—6
7.7E-8
2.6E-9
8.9E-10
3.3E-10
Handling articles or
formulations that contain
asbestos fugitive"
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
COU: Packaging, paper, plastic, toys,
hobby products
8.2E-5
3.2E-5
2.2E-5
2. IE—5
1.2E-6
4.5E-8
1.9E-8
6.8E-9
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive b
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
8.3E-6
2.1E-6
6. IE—7
2.0E-7
6.6E-9
2.IE—10
6.IE—11
2.3E-11
a The lifetime cancer risk exposure duration is 20 years which is the number of years residents are assumed to reside in a single residential location for stationary OES.
The exposure starting age is zero (birth) to consider highly exposed and sensitive population. The Averaging time for exposure years is 78 years representing the
number of vears an individual is assumed to live (Exposure Factors Handbook (U.S. EPA. 2011)).
b The lifetime cancer risk exposure duration is 1 year for non-stationary OES, IUR(iu >.
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4238 Table 5-25. General Population Inhalation of Outside Ambient Air Non-Cancer Chronic Risk Estimate Summary
OES
COU(s)
Distance from the Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
Low-end tendency non-cancer chronic MOE (benchmark = 300)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution
for disposal
7.9E1
6.0E2
3.0E3
1.1E4
9.3E5
6.9E6
2.0E7
5.8E7
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive b
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
6.8E2
4.8E3
2.6E4
1.0E5
1.2E7
1.3E8
3.3E8
8.8E8
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical,
and metal products
1.2E3
1.0E4
5.5E4
1.9E5
1.5E7
1.1E8
3.0E8
9.0E8
Handling articles or
formulations that contain
asbestos fugitive"
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
COU: Packaging, paper, plastic, toys,
hobby products
5.0E2
7.4E2
7.8E2
8.3E2
3.5E5
1.2E6
3.1E6
9.7E6
Central tendency non-cancer chronic MOE (benchmark = 300)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution
for disposal
3.4E1
2.0E2
8.6E2
2.9E3
8.7E4
2.1E6
6.0E6
1.7E7
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive h
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
9.3E2
4.9E3
2.0E4
6.9E4
2.3E6
6.0E7
1.7E8
44E8
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical,
and metal products
1.5E3
9.3E3
4.1E4
14E5
3.9E6
8.8E7
24E8
7.0E8
Handling articles or
formulations that contain
asbestos fugitive"
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
COU: Packaging, paper, plastic, toys,
hobby products
34E2
6.5E2
7.6E2
7.9E2
3.1E4
5.6E5
1.3E6
3.8E6
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OES
COU(s)
Distance from the Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive b
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
7.4E5
2.9E6
1.0E7
3.1E7
9.3E8
3.0E10
1.0E11
2.7E11
High-end tendency non-cancer chronic MOE (benchmark = 300)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution
for disposal
1.2E1
5.7E1
2.3E2
7.5E2
1.7E4
6.3E5
1.9E6
5.0E6
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive b
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
3.2E2
1.6E3
6.3E3
2.1E4
3.5E5
1.8E7
5.1E7
1.4E8
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical,
and metal products
1.5E2
7.6E2
3.0E3
9.6E3
2.6E5
7.8E6
2.3E7
6.1E7
Handling articles or
formulations that contain
asbestos fugitive"
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
COU: Packaging, paper, plastic, toys,
hobby products
1.2E2
3.2E2
4.5E2
4.9E2
8.4E3
2.3E5
5.4E5
1.5E6
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive b
COU: Construction, paint, electrical,
and metal products
COU: Furnishing, cleaning, treatment
care products
2.4E3
9.7E3
3.3E4
1.0E5
3.1E6
9.9E7
3.3E8
8.9E8
a The chronic non-cancer risk exposure duration is 20 years which is the number of years residents are assumed to reside in a single residential location for stationary
OES. The exposure starting age is zero (birth) to consider highly exposed and sensitive population. The Averaging time for exposure years is 78 years representing the
number of vears an individual is assumed to live (Exposure Factors Handbook (U.S. EPA. 2011)).
b The chronic non-cancer risk exposure duration is 1 year for non-stationary OES, IUR(iu >. The exposure starting age is zero (birth) to consider highly exposed and
sensitive population. The Averaging time for exposure years is 78 years representing the number of years an individual is assumed to live (Exposure Factors Handbook
(U.S. EPA. 2011)).
4239
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4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
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5.3.3 Risk Characterization for Potentially Exposed or Susceptible Subpopulations
The PESS groups that are of concern with regards to risks related to asbestos exposure include primarily
those with occupational exposures, children, individuals who are exposed through DIY activity, and
those who smoke.
Occupational exposures were described in Section 5.1.1 and include abroad range of occupations.
Individuals who are involved in demolition and removal of asbestos-containing material are more likely
to be exposed than individuals in other occupations. This includes firefighters, who may be exposed
during residential and commercial building firefighting activities. Higher-exposure workers high-end
(95th percentile) scenarios represent worker populations that have increased exposures from activities
that release asbestos like sanding, cutting, and others.
Children are also a particularly susceptible population, as time since first exposure is known to be an
important predictor of asbestos-related disease, see Section 5.2.2.1. As described in Section 5.2, the
earlier an individual is exposed, the greater the risk due to the latency of asbestos-related disease. For
example, onset of cancer can take up to 40 years from exposure. For this reason, individuals who are
exposed during childhood are more likely to experience asbestos-related disease.
As described in Part 1 and the prior assessments, smoking has long been recognized as potential effect
modifier for asbestos-related disease, with individuals who smoke being more susceptible to the
respiratory effects associated with asbestos.
Table 5-26 summarizes the available information in the risk evaluation to inform considerations of PESS
factors, including increased exposures and/or increased biological susceptibility. The table also
summarizes whether EPA believes the risk evaluation adequately addressed those factors in the risk
characterization or otherwise.
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Table 5-26. Summary of PESS Considerations Incorporated into the Risk Evalual
tion
PESS Categories
Potential Increased Exposures Incorporated into Exposure
Assessment
Potential Sources of Biological Susceptibility
Incorporated into Hazard Assessment
Lifestage (Age)
• Considered age at which activity-based do-it-yourself scenarios start,
like exposures starting at age zero with various durations of exposures
as well as other starting ages and durations
• Epidemiologic evidence has demonstrated that time since
first exposure is a key predictor in asbestos-related
disease (Section 5.2.2). Thus, exposures during childhood
are associated with greater risk.
Pre-existing Disease
• EPA did not identify pre-existing disease factors influencing exposure
• EPA did not identify pre-existing disease factors that are
associated with increased susceptibility.
Lifestyle Activities
• EPA evaluated exposures resulting from activity-based do-it-yourself
scenarios that may apply to certain hobbies
• Some epidemiologic evidence demonstrates a differential
response based on smoking, but evidence is not sufficient
to quantitatively estimate risk for smokers separate from
the general population (see Section 3.2.4 in Part 1 of the
Risk Evaluation for Asbestos).
• EPA did not identify other lifestyle factors associated
with susceptibility.
Occupational and
consumer
• EPA evaluated a range of occupational exposure scenarios for workers
and higher-exposure workers high-end scenario. This consideration
expands to children 16 and older because these occupational scenarios
consider exposure starting at 16 years of age.
• EPA did not identify occupational and consumer
exposures that are associated with susceptibility.
Sociodemographic
• EPA did not identify specific sociodemographic factors that influence
exposure to asbestos. This is a remaining source of uncertainty.
• EPA did not identify specific sociodemographic factors
that are associated with susceptibility.
Nutrition
• EPA did not identify nutrition factors influencing exposure
• EPA did not identify nutritional factors that are associated
with susceptibility.
Genetics
• EPA did not identify genetic factors influencing exposure
• EPA did not identify any genetic factors that are
associated with susceptibility.
Unique Activities
• EPA did not identify unique activity factors influencing exposure apart
from the activity-based D1Y scenarios
• EPA did not identify unique activities that are associated
with susceptibility.
Aggregate Exposures
• Occupational inhalation exposures aggregated
• Use of cosmetic talc powder can increase susceptibility
• EPA did not identify unique activities that are associated
with susceptibility.
Other Chemical and
Nonchemical Stressors
• EPA did not identify factors influencing exposure
• EPA did not identify other chemical or specific
nonchemical stressors that are associated with
susceptibility.
4267
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4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
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5.3.4 Risk Characterization for Aggregate and Sentinel Exposures
Exposures were considered in aggregate only for COUs that do not individually exceed benchmarks
(Section 5.1.5). As discussed in Section 5.3.2, a significant number of occupational and non-
occupational COUs exceed benchmarks alone at central tendency and/or high-end exposure scenarios,
especially those related to high-end exposures for workers. The COUs that do not individually exceed
benchmarks are indicated in Table 5-27. The aggregate analysis across exposure scenarios and COUs
figures and summaries are available in Asbestos Part 2 Draft RE - Aggregate Analysis - Fall 2023 (see
Appendix C). EPA did not identify statistics, probabilities, and frequencies for the populations engaging
in activity patterns represented in the aggregate analysis scenarios, but the analysis identified possible
activity patterns that exceed benchmarks.
Table 5-27. Exposure Scenarios Included in Aggregate Analysis
Exposure
Scenario
Affected Population(s) - HE
Affected Population(s) - CT
Take-Home
DIYer
General
Population
Worker
Take-Home
DIYer
General
Population
MOE
ELCR
MOE
ELCR
MOE
ELCR
MOE
ELCR
MOE
ELCR
MOE
ELCR
MOE
ELCR
Demolition,
renovation,
maintenance
X
x / ~
X
~ /*
(<30 m)
~ /*
~ /*
~ /*
(<10 m)
Firefighting/
disaster -
career
X
~ /*
(<10 m)
Firefighting/
disaster -
volunteer
~ /*
(<10 ill)
Removal/
repair of
machinery
X
X
~ /*
(<60 m)
X
X
~ /*
(<10 ill)
Handling
articles or
formulations
X
X
~ /*
(<100 ill)
X
X
X
~ /*
(<100 ill)
Waste
handling
X
X
-
-
~ /*
(<30 m)
~ /*
(<100 ill)
X
X
-
-
~ /*
(<10 m)
~ /*
(<100 ill)
x / S Some activities for the DIYer (modifications, removal, disturbance of asbestos containing materials) and distances for the
general population exceeded benchmarks and were not use in the aggregation each of these populations have activities and
distances from the source that were not above the benchmarks and were included in the aggregation.
(<10, or 30, or, 100m) Less than this distance was not included in the aggregation, further distances were included in the
aggregation.
^ Exposure scenarios were used in the aggregation.
x Exposure scenarios were not used in the aggregation because already exceeded benchmark.
The aggregate exposure scenarios that exceed benchmarks include the following:
• Lifetime cancer risk
o Take-home, DIYers, and general population for repair/removal of commercial and
industrial appliances or machinery COU at all distances
o Take-home, DIYers, and general population for demolition COU at <30 m distance
o Occupational exposures for firefighting (career) or demolition COUs combined with
take-home, DIY, and general population exposures
• Non-cancer chronic risk
o DIYers LE disturbance of construction and furnishing products COUs
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4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
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4327
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o DIYers LE construction materials and furnishing products and CT construction materials
products COUs
Many CT and HE exposure scenarios exceeded risk benchmarks alone, and thus were not included in the
aggregate analysis.
Additional details on the aggregate analysis are available in Appendix M.
5.3.5 Overall Confidence and Remaining Uncertainties in Human Health Risk
Characterization
Human health risk characterization evaluated confidence from occupational, take-home, consumer
DIYer, and general population exposures and human health hazards. Hazard confidence and uncertainty
is represented by health outcome and exposure duration as reported in Section 5.2, which presents the
confidence, uncertainties, and limitations of the human health hazards for asbestos. Confidence in the
exposure assessment has been synthesized in the respective weight of scientific evidence conclusion
sections for occupational exposures (Section 5.1.1.4), take-home exposures (Section 5.1.2.2), consumer
DIYer exposures (Section 5.1.3.3), and general population exposures (Section 5.1.4.3). Table 5-28
provides a summary of confidence for exposures and hazards for lifetime cancer and non-cancer chronic
endpoints for the COUs that resulted in any cancer and non-cancer risks.
Uncertainties associated with the occupational exposure assessment as describe in Section 5.1.1.4,
include a lack of reported data from databases such as TRI, and NEI. Site-specific data were only
available for a small number of current occupational activities, and it is not clear if these data are
representative of current workplace practices.
Uncertainties associated with the general population exposures assessment included the lack of site-
specific information, the incongruence between the modeled concentrations and measured
concentrations in the monitoring data, and the complexity of the assessed exposure scenarios.
The quantitative values are robust because they are based on historical occupational epidemiology
cohorts with use of the longest follow-up for each cohort or the most pertinent exposure-response when
a cohort had been the subject of more than one publication. Additionally advanced exposure
measurement methods are reflected in the underlying data resulting in exposure estimates that are of
high confidence. Furthermore, longer follow-up times increase the statistical power of the study as more
mortality is observed. Other notable strengths include accounting for laryngeal and ovarian cancers,
which are causally associated with asbestos exposure, and accounting for under-ascertainment of
mesothelioma.
When deriving hazard values for risk assessment there are always uncertainties. These uncertainties are
described in the white paper (U.S. EPA. 2023o) and in Section 5.2. Uncertainties are related to the
following: use of PCM over TEM in available exposure measurement data; use of impinger sampling
data for early asbestos exposure; use of mortality data rather than incidence data; under ascertainment of
mesothelioma; inter individual variability and confounding due to smoking. However, these
uncertainties were accounted for to the extent possible in modeling and the data is robust when
considering the strengths and uncertainties.
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Table 5-28. Asbestos Evidence Table Summarizing Overall Confidence for Human Health Lifetime Cancer and Non-Cancer Chronic
cou
Subcategory
OES or DIY Scenario
Exposure
Confidence
Hazard
Confidence
Risk
Characterization
Confidence
Occupational
COU: Construction, paint, electrical, and metal products
subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone, plaster,
cement, glass, and ceramic articles
COU: Furnishing, cleaning, treatment care products
subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
Handling asbestos-containing building
materials during maintenance, renovation,
and demolition activities (workers and
ONUs)
++
+++
++
COU: Construction, paint, electrical, and metal products
subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone, plaster,
cement, glass, and ceramic articles
COU: Furnishing, cleaning, treatment care products
subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
Handling of asbestos-containing building
materials during firefighting or other
disaster response activities (career
workers)
++ /+++
+++
+++
Handling of asbestos-containing building
materials during firefighting or other
disaster response activities (volunteer
workers)
COU: Construction, paint, electrical, and metal products
subcategory: Machinery, mechanical appliances, electrical/electronic
articles and other machinery, mechanical appliances,
electronic/electronic articles
Use, repair, or removal of industrial and
commercial appliances or machinery
containing asbestos (workers and ONUs)
++/+++
+++
+++
COU: Construction, paint, electrical, and metal products
subcategory: Fillers and putties, electrical batteries and accumulators,
and solvent-based/water-based paint
COU: Furnishing, cleaning, treatment care products
subcategory: Furniture & furnishings including stone, plaster, cement,
glass, and ceramic articles; metal articles; or rubber articles
COU: Packaging, paper, plastic, toys, hobby products
subcategory: Packaging (excluding food packaging), including rubber
articles; plastic articles (hard); plastic articles (soft) and Toys
intended for children's use (and child dedicated articles), including
fabrics, textiles, and apparel; or plastic articles (hard)
Handling articles or formulations that
contain asbestos (workers and ONUs)
++
+++
++
COU and subcategory: Disposal, including distribution for disposal
Waste handling, disposal, and treatment
(workers and ONUs)
++
+++
++
Take-home
COU: Construction, paint, electrical, and metal products
Maintenance, renovation, and demolition
handler and bystander
++
+++
++
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cou
Subcategory
OES or DIY Scenario
Exposure
Confidence
Hazard
Confidence
Risk
Characterization
Confidence
subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone, plaster,
cement, glass, and ceramic articles
COU: Furnishing, cleaning, treatment care products
subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
COU: Construction, paint, electrical, and metal products
Subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone, plaster,
cement, glass, and ceramic articles
COU: Furnishing, cleaning, treatment care products
subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
Firefighting and other disaster response
activities (career) handler and bystander
++
+++
++
Firefighting and other disaster response
activities (volunteer) handler and
bystander
++
+++
++
COU: Construction, paint, electrical, and metal products
subcategory: Machinery, mechanical appliances, electrical/electronic
articles and other machinery, mechanical appliances,
electronic/electronic articles
Use, repair, or removal of industrial and
commercial appliances or machinery
containing asbestos handler and bystander
++
+++
++
COU: Construction, paint, electrical, and metal products
subcategory: Solvent-based/water-based paint, fillers, and putties
COU: Furnishing, cleaning, treatment care products
subcategory: Furniture & furnishings including stone, plaster, cement,
glass, and ceramic articles; metal articles; or rubber articles
COU: Packaging, paper, plastic, toys, hobby products
subcategory: Packaging (excluding food packaging), including rubber
articles; plastic articles (hard); plastic articles (soft) and Toys
intended for children's use (and child dedicated articles), including
fabrics, textiles, and apparel; or plastic articles (hard)
Handling articles or formulations that
contain asbestos (battery insulators,
burner mats, plastics, cured
coatings/adhesives/sealants) handler and
bystander
++
+++
++
COU and subcategory: Disposal, including Distribution for Disposal
Waste handling, disposal, and treatment
handler and bystander
++
+++
++
Consumer DIYer / bystander
Chemical substances in
construction, paint, electrical,
and metal products
Construction and building
materials covering large surface
areas: paper articles; metal articles;
stone, plaster, cement, glass and
ceramic articles
Outdoor, disturbance/repair (sanding or
scraping) of roofing materials DIYer
++
+++
++
Outdoor, disturbance/repair (sanding or
scraping) of roofing materials bystander
+
+++
+
Outdoor, removal of roofing materials
DIYer
++
+++
++
Outdoor, removal of roofing materials
bystander
+
+++
+
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cou
Subcategory
OES or DIY Scenario
Exposure
Confidence
Hazard
Confidence
Risk
Characterization
Confidence
Chemical substances in
construction, paint, electrical,
and metal products
Indoor, removal of plaster DIYer
++
+++
++
Indoor, removal of plaster bystander
+
+++
+
Indoor, disturbance (sliding) of ceiling
tiles DIYer
++
+++
++
Indoor, disturbance (sliding) of ceiling
tiles bystander
+
+++
+
Indoor, removal of ceiling tiles DIYer
++
+++
++
Indoor, removal of ceiling tiles bystander
+
+++
+
Indoor, maintenance (chemical stripping,
polishing, or buffing) of vinyl floor tiles
DIYer
++
+++
++
Indoor, maintenance (chemical stripping,
polishing, or buffing) of vinyl floor tiles
bystander
+
+++
+
Indoor, removal of vinyl floor tiles DIYer
++
+++
++
Indoor, removal of vinyl floor tiles
bystander
+
+++
+
Indoor, disturbance/repair (cutting) of
attic insulation DIYer
++
+++
++
Indoor, disturbance/repair (cutting) of
attic insulation bystander
+
+++
+
Indoor, moving and removal (with
vacuum) of attic insulation DIYer
++
+++
++
Indoor, moving and removal (with
vacuum) of attic insulation bystander
+
+++
+
Fillers and putties
Indoor, disturbance (pole or hand sanding
and cleaning) of spackle DIYer
++
+++
++
Indoor, disturbance (pole or hand sanding
and cleaning) of spackle bystander
+
+++
+
Indoor, disturbance (sanding and
cleaning) of coatings, mastics, and
adhesives DIYer
++
+++
++
Indoor, disturbance (sanding and
cleaning) of coatings, mastics, and
adhesives bystander
+
+++
+
Indoor, removal of floor tile/mastic
DIYer
++
+++
++
Indoor, removal of floor tile/mastic
bystander
+
+++
+
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cou
Subcategory
OES or DIY Scenario
Exposure
Confidence
Hazard
Confidence
Risk
Characterization
Confidence
Indoor, removal of window caulking
DIYer
++
+++
++
Indoor, removal of window caulking
bystander
+
+++
+
Chemical substances in
furnishing, cleaning, treatment
care products
Construction and building
materials covering large surface
areas, including fabrics, textiles,
and apparel
Use of mittens for glass manufacturing,
(proxy for oven mittens and potholders)
DIYer
+
+++
+
Use of mittens for glass manufacturing,
(proxy for oven mittens and potholders)
bystander
+
+++
+
General population
COU: construction, paint, electrical, and metal products
subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone, plaster,
cement, glass, and ceramic articles
COU: furnishing, cleaning, treatment care products
subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
Maintenance, renovation, and demolition
handler and bystander
++
+++
++
COU: Construction, paint, electrical, and metal products
subcategory: Construction and building materials covering large
surface areas, including paper articles; metal articles; stone, plaster,
cement, glass, and ceramic articles
COU: Furnishing, cleaning, treatment care products
subcategory: Construction and building materials covering large
surface areas, including fabrics, textiles, and apparel
Firefighting and other disaster response
activities (career) handler and bystander
++
+++
++
Firefighting and other disaster response
activities (volunteer) handler and
bystander
++
+++
++
COU: Construction, paint, electrical, and metal products
subcategory: Machinery, mechanical appliances, electrical/electronic
articles and other machinery, mechanical appliances,
electronic/electronic articles
Use, repair, or removal of industrial and
commercial appliances or machinery
containing asbestos handler and bystander
++
+++
++
COU: Construction, paint, electrical, and metal products
subcategory: Solvent-based/water-based paint, fillers, and putties
COU: Furnishing, cleaning, treatment care products
subcategory: Furniture & furnishings including stone, plaster, cement,
glass, and ceramic articles; metal articles; or rubber articles
COU: Packaging, paper, plastic, toys, hobby products
subcategory: Packaging (excluding food packaging), including rubber
articles; plastic articles (hard); plastic articles (soft) and Toys
intended for children's use (and child dedicated articles), including
fabrics, textiles, and apparel; or plastic articles (hard)
Handling articles or formulations that
contain asbestos (battery insulators,
burner mats, plastics, cured
coatings/adhesives/sealants) handler and
bystander
++
+++
++
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cou
Subcategory
OES or DIY Scenario
Exposure
Confidence
Hazard
Confidence
Risk
Characterization
Confidence
COU and subcategory: Disposal, including distribution for disposal
Waste handling, disposal, and treatment
handler and bystander
++
+++
++
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5.3.5.1 Occupational Risk Estimates
Table 5-6 provides a summary of the weight of scientific evidence for each occupational exposure
scenario (OES), indicating whether monitoring data was reasonably available, the number of data points
identified, the quality of the data, overall confidence in the data, and whether the data was used to
estimate inhalation exposures for workers and ONUs. For all OES and worker populations, occupational
exposure estimates were assigned Moderate or Moderate to Robust confidence according to the weight
of scientific evidence of the monitoring data available. Appendix E provides further details of the overall
confidence for inhalation exposure estimates for each OES assessed. Uncertainties in occupational
exposure estimation include representativeness of data, data that may be inherently biased, number of
working years, and lack of sufficient metadata. Also, there are uncertainties with respect to the approach
for estimating the number of workers using NAICS codes and BLS data. The strengths, limitations,
assumptions, and key sources of uncertainty for the occupational exposure assessment are detailed in
Section 5.1.1.4.1.
5.3.5.2 Take-Home Risk Estimates
Sections 3.1.2.3 and 5.1.2.2 summarize the data used in this analysis and the approaches developed to
evaluate asbestos risk from take-home exposures. The studies used in the take-home exposure analysis
contained data that were specific to two types of activities that are related to building/construction
materials and machinery. The other studies used simulated asbestos fiber concentrations ranges to
generalize the applicability of the data to more than one type of product and activity. In addition, the
studies also measured exposure concentrations to bystanders as part of their objectives, which means the
bystander concentrations used in this evaluation were measured just as the garment handler and the risk
estimates for the bystander have the same uncertainties as the handler. EPA used all the data in a
regression approach to identify central- and high-end tendencies for all OESs/COUs. The use of specific
activity product release data and generated range of concentrations data facilitated the generalization to
all COUs. The regression approach used one garment (unit) to a loading event and subsequent laundry
activity minimizes uncertainties and variability while decreasing complexity of the overall approach.
5.3.5.3 Consumer DIY Risk Estimates
Asbestos Releases from Products Data
Sections 3.1.3.5 and 5.1.3.3 summarize the available information on the consumer DIY COUs and
relevant exposure scenarios. EPA only assessed activity-based scenarios in which asbestos containing
products are modified in a way that releases fibers and are subsequently inhaled by the DIYer and
bystander. Due to the lack of specific information on DIY consumer exposures, occupational studies
measuring exposure to professionals were often used as proxies. There is uncertainty in using
occupational data for consumers due to differences in building volumes, air exchange rates, available
engineering controls, and potential use of PPE.
Applicability and Generalization of Activity-Base DIY Scenarios
The activity-base DIY scenarios in this asbestos part 2 risk evaluation were built based on the
information identified via the systematic review process. EPA was able to identify information for most
COUs and product examples within, however not all possible activities, or activity durations, or activity
locations were sampled and reported, hence there is some extrapolation and generalization to apply the
information to DIY scenarios. EPA aims to cover the bulk of the possible scenarios with the low-,
central, and high-end use pattern assumptions used to estimate exposure durations and frequencies
summarized in Table 5-11.
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5.3.5.4 General Population Risk Estimates
The releases into ambient air from occupational activities and subsequent general population inhalation
exposure are described in Sections 3.2, 3.3, andO 5.1.4. The average daily release calculated from sites
reporting to TRI, NEI or NRC was applied to the total number of sites, however it is uncertain how
accurate this average release is to actual releases at these sites; therefore, releases may be higher or
lower than the calculated amount. For releases modeled with TRI/NEI/NRC, the weight of scientific
evidence conclusion was moderate to robust since information on the conditions of use of asbestos at
sites in TRI and NEI is limited, and NRC does not provide the condition of use of asbestos at sites. For
the Handling Asbestos-Containing Building Materials During Firefighting or Other Disaster Response
Activities OES, the weight of scientific evidence conclusion was moderate since surrogate data from a
different OESs were utilized. The combined estimates of releases to ambient air and the use of these data
to estimate general population exposure concentrations and risk at various distances from the activity
were given a moderate confidence level. See Sections 3.3.1.4 and 5.1.4.3 for a summary of the weight of
scientific evidence for general population exposures to releases from occupational activities.
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6 UNREASONABLE RISK DETERMINATION
TSCA section 6(b)(4) requires EPA to conduct a risk evaluation to determine whether a chemical
substance presents an unreasonable risk of injury to health or the environment, without consideration of
costs or other non-risk factors—including an unreasonable risk to a potentially exposed or susceptible
subpopulation (PESS) identified by EPA as relevant to the risk evaluation under the TSCA COUs.
EPA is preliminarily determining that asbestos presents an unreasonable risk of injury to health under
the COUs. Risk of injury to the environment does not contribute to EPA's preliminary determination of
unreasonable risk. This draft unreasonable risk determination is based on the information in the 2020
Risk Evaluation for Asbestos Part 1: Chrysotile Asbestos (U.S. EPA. 2020c) and the appendices and
supporting documents, as well as on the previous sections of this Draft Risk Evaluation for Asbestos
Part 2: Supplemental Evaluation Including Legacy Uses and Associated Disposals and the appendices
and supporting documents—in accordance with TSCA section 6(b), as well as (1) the best available
science (TSCA section 26(h)), and (2) weight of scientific evidence standards (TSCA section 26(i)), and
(3) relevant implementing regulations in 40 CFR 702.
The risk identified for asbestos under the COUs evaluated in this Draft Risk Evaluation for Asbestos,
Part 2: Supplementary Evaluation Including Legacy Uses and Associated Disposals supplements the
risk of asbestos determined in the 2020 Risk Evaluation for Asbestos, Part 1: Chrysotile Asbestos (U.S.
EPA. 2020c) (see also Section 1.1. Scope of the Risk Evaluation). The Agency is now making a single
unreasonable risk determination for asbestos as a chemical substance. The majority of the COUs in this
Draft Part 2 Risk Evaluation that EPA preliminarily determines contribute to the unreasonable risk
posed by asbestos relate to handling or disturbing articles into which asbestos was incorporated in the
past, but for which the manufacture (including import), processing, and distribution of these articles no
longer occurs. The rough handling or disturbance of these articles can cause asbestos to be released as
respirable (friable) asbestos fibers. As noted in Section 6.1.1, and further discussed in Sections 6.2.1.2
and 6.2.1.3, in proposing this risk determination, EPA believes it is appropriate to evaluate the levels of
risk present in baseline scenarios where personal protective equipment (PPE) is not assumed to be used
by workers.
EPA is preliminarily determining the following COUs in the Draft Part 2 Risk Evaluation, considered
singularly or in combination with other exposures, contribute to the unreasonable risk of asbestos:
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - construction and building materials covering large surface areas - paper articles;
metal articles; stone plaster, cement, glass, and ceramic articles;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - machinery, mechanical appliances, electrical/electronic articles;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - other machinery, mechanical appliances, electronic/electronic articles;
• Industrial/commercial use - chemical substances in furnishing, cleaning, treatment care products
- construction and building materials covering large surface areas - fabrics, textiles, and apparel;
• Industrial/commercial use - chemical substances in furnishing, cleaning, treatment care products
- furniture and furnishings - stone, plaster, cement, glass, ceramic articles, metal articles, and
rubber articles;
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
construction and building materials covering large surface areas - paper articles; metal articles;
stone, plaster, cement, glass, and ceramic articles;
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• Consumer use - chemical substances in construction, paint, electrical, and metal products -
fillers and putties;
• Consumer use - chemical substances in furnishing, cleaning, treatment care products - furniture
and furnishings - stone, plaster, cement, glass, and ceramic articles; metal articles; or rubber
articles; and
• Disposal - distribution for disposal.
EPA is preliminarily determining that the following COUs are not expected to contribute to the
unreasonable risk:
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - fillers and putties*;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - solvent based/water-based paint*;
• Industrial/commercial use - chemical substances in products not described by other codes -
other (aerospace applications);
• Industrial/commercial use - mining of non-asbestos commodities - mining of non-asbestos
commodities;
• Industrial/commercial use - laboratory chemicals - laboratory chemicals;
• Industrial/commercial use - chemical substances in automotive, fuel, agriculture, outdoor use
products - lawn and garden care products; and
• Consumer use - chemical substances in automotive, fuel, agriculture, outdoor use products -
lawn and garden care products.
Note that EPA considered the specific circumstances related to two of the COUs that do not contribute
to the unreasonable risk of asbestos, marked with an asterisk (*) above. Asbestos-containing fillers and
putties and solvent and water-based paints already applied to articles are unlikely to release asbestos
fibers unless disturbed though rough handling, which EPA does not expect for these COUs. However, it
is possible that asbestos fiber releases may occur during the rough handling of building materials,
machinery or furnishings containing putties and paints during construction, renovation, demolition,
repairs, and other similar activities that make the asbestos-containing material friable. These releases are
already represented by COUs that were preliminarily determined to contribute to the unreasonable risk
of asbestos.
EPA did not have sufficient information to determine whether the following COUs contribute to the
unreasonable risk, and therefore, the Agency cannot state that these COUs contribute to the
unreasonable risk of asbestos:
• Industrial/commercial use - chemical substances in products not described by other codes -
other (artifacts);
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - electrical batteries and accumulators;
• Industrial/commercial use - chemical substances in packaging, paper, plastic - packaging
(excluding food packaging) - rubber articles; plastic articles (hard); plastic articles (soft);
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
machinery, mechanical appliances, electrical/ electronic articles;
• Consumer use - chemical substances in products not described by other codes - other (artifacts);
• Consumer use - chemical substances in packaging paper, plastic, toys, hobby products -
packaging (excluding food packaging) - rubber articles; plastic articles (hard); plastic articles
(soft);
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4503
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4507
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4514
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• Consumer use - chemical substances in construction, paint, electrical, and metal products -
solvent-based/ water-based paint;
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
construction and building materials covering large surface areas - paper articles; metal articles;
stone, plaster, cement, glass, and ceramic articles;
• Consumer use - chemical substances in furnishing, cleaning, treatment care products -
construction and building materials covering large surface areas - fabrics, textiles, and apparel;
and
• Consumer use - chemical substances in packaging paper, plastic, toys, hobby products - toys
intended for children's use (and child dedicated articles) - fabrics, textiles, and apparel; or plastic
articles (hard).
This draft risk determination for asbestos as a chemical substance reflects policy changes announced by
EPA in June 2021(and further discussed in Section 6.1.1) and is based on the risk estimates and risk-
related factors in the Part 1 Risk Evaluation for Asbestos. The policy changes announced by the Agency
in June 2021 do not change the conditions of use that contribute to the unreasonable risk of asbestos
evaluated in Part 1. In addition, this draft risk determination is based on the risk estimates and risk-
related factors presented in this Draft Risk Evaluation for Asbestos Part 2: Supplemental Evaluation
Including Legacy Uses and Associated Disposals.
Whether EPA makes a determination of unreasonable risk for a particular chemical substance under
amended TSCA depends upon risk-related factors beyond exceedance of benchmarks, such as the
endpoint under consideration, the reversibility of effect, exposure-related considerations (e.g., duration,
magnitude, or frequency of exposure, or population exposed), and the confidence in the information
used to inform the hazard and exposure values. The Agency generally has a moderate or robust degree
of confidence in its characterization of risk where the scientific evidence weighed against the
uncertainties is robust enough to characterize hazards, exposures, and risk estimates, as well as where
the uncertainties inherent in all risk estimates do not undermine EPA's confidence in its risk
characterization. This draft risk evaluation discusses important assumptions and key sources of
uncertainty in the risk characterization. These are described in more detail in the respective weight of
scientific evidence conclusions sections for fate and transport, environmental release, environmental
exposures, environmental hazards, and human health hazards. It also includes overall confidence and
remaining uncertainties sections for human health and environmental risk characterizations.
In making the asbestos unreasonable risk determination, EPA considered risk estimates with an overall
confidence rating of low (slight), medium (moderate), or high (robust). In general, the Agency makes an
unreasonable risk determination based on risk estimates that have an overall confidence rating of
moderate or robust, since those confidence ratings indicate the scientific evidence is adequate to
characterize risk estimates despite uncertainties or is such that it is unlikely the uncertainties could have
a significant effect on the risk estimates (Section 5.3.5).
If in the final risk evaluation for asbestos EPA determines that asbestos presents an unreasonable risk of
injury to health or the environment under the COUs, EPA will initiate risk management rulemaking to
mitigate identified unreasonable risk associated with asbestos under the COUs by applying one or more
of the requirements under TSCA section 6(a) to the extent necessary so that asbestos no longer presents
such risk. Following issuance of the Part 1 Risk Evaluation for Asbestos, EPA initiated rulemaking to
address the unreasonable risk identified (87 FR 21706). After considering public comment on that
proposed rule, EPA is finalizing regulations of certain conditions of use of chrysotile asbestos. EPA
would expect to issue a proposed rule following completion of this Part 2 Risk Evaluation for Asbestos
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in accordance with section 6(a). EPA would also consider whether such risk may be prevented or
reduced to a sufficient extent by action taken under another federal law, such that referral to another
agency under TSCA section 9(a) or use of another EPA-administered authority to protect against such
risk pursuant to TSCA section 9(b) may be appropriate.
6.1 Background
6.1.1 Policy Changes Relating to a Single Risk Determination on the Chemical Substance
and Assumption of PPE Use by Workers
From June 2020 to January 2021, EPA published risk evaluations on the first 10 chemical substances,
including the 2020 Risk Evaluation for Asbestos, Part 1: Chrysotile Asbestos (U.S. EPA. 2020c). The
risk evaluations included individual unreasonable risk determinations for each COU evaluated. The
determinations that particular conditions of use did not present an unreasonable risk were issued by
order under TSCA section 6(i)(l).
In accordance with Executive Order 13990 ("Protecting Public Health and the Environment and
Restoring Science to Tackle the Climate Crisis") (EOP. 2021a) and other Administration priorities
(EOP. 2021b. c, d; EPA Press Office. 2021). EPA reviewed the risk evaluations for the first 10 chemical
substances to ensure that they met the requirements of TSCA, including conducting decision-making in
a manner that is consistent with the best available science and weight of scientific evidence.
As a result of this review, EPA announced plans to revise specific aspects of certain of the first 10 risk
evaluations in order to ensure that the risk evaluations appropriately identify unreasonable risks and
thereby can help ensure the protection of health and the environment (EPA Press Office. 2021). The
changes to no longer assume the use of PPE in making the unreasonable risk determination does not
change what conditions of use evaluated under Part 1 would contribute to a single unreasonable risk
determination for asbestos as a chemical substance. Further discussion of the decision to not rely on
assumptions regarding the use of PPE in this Draft Risk Evaluation for Asbestos Part 2: Supplemental
Evaluation Including Legacy Uses and Associated Disposals is provided in Sections 6.2.1.2 and 6.2.1.3
below. With the issuance of the draft Part 2 Risk Evaluation for Asbestos, the Agency is preliminarily
determining that this approach will apply to this draft risk evaluation. In addition, as discussed below in
Sections 6.2.1.2 and 6.2.1.3, in proposing this risk determination, EPA believes it is appropriate to
evaluate the levels of risk present in baseline scenarios where PPE is not assumed to be used by workers;
although the Agency does not question the information received regarding the occupational safety
practices often followed by many industry respondents.
Making unreasonable risk determinations based on the baseline scenario without assuming PPE should
not be viewed as an indication that EPA believes there are no occupational safety protections in place at
any location or that there is widespread noncompliance with applicable OSHA standards. EPA
understands that there could be occupational safety protections in place at workplace locations.
Nevertheless, not assuming use of PPE reflects the Agency's recognition that unreasonable risk may
exist for subpopulations of workers that may be highly exposed because they are (1) not covered by
OSHA standards; (2) their employers are out of compliance with OSHA standards, (3) many of OSHA's
chemical-specific permissible exposure limits largely adopted in the 1970s are described by OSHA as
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being "outdated and inadequate for ensuring protection of worker health"4; or (4) EPA finds
unreasonable risk for purposes of TSCA notwithstanding OSHA requirements.
With regard to the specific circumstances of asbestos, as further explained below, EPA has preliminarily
determined that a single risk determination on the chemical substance asbestos is appropriate in order to
protect health and the environment. The single risk determination on the chemical is appropriate for
asbestos because there are benchmark exceedances for multiple COUs (spanning across most aspects of
the chemical life cycle—from manufacturing [including import], processing, industrial, commercial and
consumer use, and disposal) for human health. Furthermore, the risk of severe health effects—
specifically mesothelioma and lung, ovarian, and laryngeal cancers—is associated with chronic
inhalation exposures of asbestos. Because these chemical-specific properties cut across the COUs within
the scope of the draft risk evaluation and a substantial amount of the COUs contribute to the
unreasonable risk, it is therefore appropriate for the Agency to propose a determination that the chemical
substance presents an unreasonable risk. For those COUs assessed in the 2020 Risk Evaluation for
Asbestos, Part 1: Chrysotile Asbestos (U.S. EPA. 2020c). EPA does not intend to amend, nor does a
single risk determination on the chemical substance require, amending the underlying scientific analysis
and the risk characterization.
The discussion of these issues in this preliminary risk determination would supersede any conflicting
statements in the 2020 Risk Evaluation for Asbestos, Part 1: Chrysotile Asbestos (U.S. EPA. 2020c) and
the response to comments document (Summary of External Peer Review and Public Comments for
Asbestos and Disposition for Asbestos, Part 1: Chrysotile Asbestos (U.S. EPA. 2020c)). EPA also views
the peer-reviewed hazard and exposure assessments and associated risk characterization of Part 1 as
robust and upholding the standards of best available science and weight of scientific evidence per TSCA
sections 26(h) and (i).
6.2 Unreasonable Risk to Human Health
Calculated risk estimates (MOEs or cancer risk estimates) can provide a risk profile of asbestos by
presenting a range of estimates for different health effects for different COUs. When characterizing the
risk to human health from occupational exposures during risk evaluation under TSCA, EPA conducts
baseline assessments of risk and makes its determination of unreasonable risk from a baseline scenario
that does not assume use of respiratory protection or other PPE. Making unreasonable risk
determinations based on the baseline scenario should not be viewed as an indication that EPA believes
there are no occupational safety protections in place at any location, or that there is widespread
noncompliance with existing regulations that may be applicable to asbestos. Rather, it reflects EPA's
recognition that unreasonable risk may exist for subpopulations of workers that may be highly exposed
because they are not covered by OSHA standards—such as self-employed individuals and public sector
workers who are not covered by a State Plan, or because their employer is out of compliance with
OSHA standards, or because EPA finds unreasonable risk for purposes of TSCA notwithstanding
existing OSHA requirements. In addition, the risk estimates are based on exposure scenarios with
monitoring data that may reflect existing requirements, such as those established by EPA (i.e., NESHAP
under the Clean Air Act and the Asbestos Hazard Emergency Response Act under TSCA Title II),
OSHA (i.e., asbestos standard), or industry or sector best practices. A calculated MOE that is less than
the benchmark MOE is a starting point for informing a determination of unreasonable risk of injury to
4 As noted on OSHA's Annotated Table of Permissible Exposure Limits: "OSHA recognizes that many of its permissible
exposure limits (PELs) are outdated and inadequate for ensuring protection of worker health. Most of OSHA's PELs were
issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970 and have not been updated since that
time" (OSHA. 2016).
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health, based on non-cancer effects. Similarly, a calculated cancer risk estimate that is greater than the
cancer benchmark is a starting point for informing a determination of unreasonable risk of injury to
health from cancer. It is important to emphasize that these calculated risk estimates alone are not
"bright4ine" indicators of unreasonable risk.
6.2.1 Unreasonable Risk to Human Health Asbestos Part 2
6.2.1.1 Populations and Exposures EPA Assessed to Determine Unreasonable Risk to
Human Health
EPA evaluated risk to workers—including ONUs (male and female, adults and adolescents (>16 years
old)), handlers (>16 to 40 years old), and bystanders (0 to 78 years old)—with take-home exposures
from the workplace (e.g., people exposed to asbestos fibers adhering to garments taken home by
workers/ONUs); consumer users (male and female, adults and adolescents [>16 to 78 years old]);
bystanders (male and female, 0 to 20 years old); and the general population using reasonably available
monitoring and modeling data for chronic inhalation exposures. The Agency evaluated cancer and non-
cancer chronic risk estimates from such inhalation exposures and considered the distance of the general
population from the source of the exposures. Descriptions of the data used for human health exposure
and human health hazards are provided in Section 5.1 and Section 5.2 of this draft risk evaluation.
Uncertainties for overall exposures and hazards are presented in Section 5.3.5 and summarized in Table
5-27 and are considered in the unreasonable risk determination.
6.2.1.2 Summary of the Unreasonable Risks to Human Health
EPA is preliminarily determining that the unreasonable risks presented to workers (including ONUs and
firefighters), handlers of asbestos contaminated clothing from occupational activities, consumers,
bystanders, and general population by exposure to asbestos, are due to
• cancer and non-cancer effects in workers, including ONUs and firefighters, from inhalation
exposures;
• cancer and non-cancer effects in handlers and bystanders from occupational take-home
inhalation exposures;
• cancer and non-cancer effects in consumers and bystanders from inhalation exposures; and
• cancer and non-cancer effects in general population from inhalation exposures.
EPA is preliminarily determining that the cancer human health hazards described in the 2020 Part 1 risk
evaluation are still relevant and valid to draft part 2 of the risk evaluation. The human health hazard
studies show that asbestos exposure is associated with lung cancer, mesothelioma, laryngeal cancer, and
ovarian cancer. When available, EPA used monitoring data to characterize central tendency (median)
and high-end (95th percentile) inhalation exposures. In cases where no ONU sampling data are
available, EPA typically assumes that ONU inhalation exposure is either comparable to area monitoring
results or assumes that ONU exposure is likely lower than workers. For the Disposal COU, EPA did not
have monitoring data to estimate inhalation exposure for ONUs, exposure for ONUs was addressed
using the central tendency for estimates of worker inhalation exposure. In addition, for some COUs,
EPA classified workers in two categories: "higher exposure-potential workers" are workers whose
activities may directly generate friable asbestos through actions such as cutting, grinding, welding, or
tearing asbestos-containing materials; and "lower exposure-potential workers" are workers who are not
expected to generate friable asbestos but may come into direct contact with friable asbestos while
performing their required work activities. More information on EPA's confidence in these risk estimates
for inhalation and the uncertainties associated with them can be found in Section 5.2.1.2 of this draft risk
evaluation.
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For workers, including ONUs, EPA estimated risks using several occupational exposure scenarios
related to the central tendency (median) and high-end (95th percentile) estimates of exposure. For
workers and ONUs, cancer risks in excess of the benchmark (1 x 10~4) were indicated for virtually all
quantitatively assessed COUs when PPE was not used. For handlers, consumers (DIYers), and
bystanders of consumer use, EPA estimated cancer risks resulting from inhalation exposures. For
handlers, cancer risks in excess of the benchmark (1 x 10~6) were indicated for six COUs. For consumers
and bystanders, cancer risks in excess of the benchmark (1 x 10~6) were indicated for three COUs.
With respect to non-cancer health endpoints upon which EPA is basing this unreasonable risk
determination, the Agency has moderate overall confidence in the (1) non-cancer hazard value POD,
which is derived from epidemiologic data and represents a 24-hour value and exposure concentrations
and have been adjusted to match the time duration for inhalation exposure; and (2) most sensitive and
robust non-cancer health effects from localized pleural thickening of lung tissue in humans based on
epidemiologic data from an occupational cohort (see Section 5.3.2). EPA's exposure and overall risk
characterization confidence levels varied and are summarized in Table 5-27.
The non-cancer risk estimates for workers, ONUs, consumers, bystanders, and the general population
are presented in Section 5.3.2, including a benchmark MOE of 300 for the most sensitive and robust
endpoint. A summary of health risk estimates is available for workers and ONUs (Section 5.3.2.1), take-
home exposures (Section 5.3.2.2), consumers and bystanders (Section 5.3.5.3), and general population
(Section 5.3.5.4).
6.2.1.3 Basis for EPA's Determination of Unreasonable Risk to Human Health
In developing the exposure and hazard assessments for asbestos, EPA analyzed reasonably available
information to ascertain whether some human populations may have greater exposure and/or
susceptibility than the general population to the hazard posed by asbestos. For the asbestos draft risk
evaluation, EPA identified as PESS groups that are of concern with regards to risks related to asbestos
exposure—including those with occupational exposures, children, individuals who are exposed through
DIY activity, and those who smoke (see Section 5.3.3 and Table 5-25). The occupational exposures
include a broad range of occupations, including individuals involved in demolition and disposal of
asbestos-containing material as well as firefighters who may be exposed during residential and
commercial building firefighting activity. Similarly, consumers who engage in DIY activities related to
demolition and disposal of asbestos-containing materials have greater risk.
Risk estimates based on central tendency (median) exposure levels are generally estimates of average or
typical exposure. High-end exposure levels (e.g., 95th percentile or "high intensity use") are generally
intended to cover individuals with sentinel exposure levels. For several COUs, EPA considered sentinel
exposures by considering risks to populations who may have upper bound exposures; for example,
workers and ONUs who perform activities with higher exposure potential or consumers who have higher
exposure potential (e.g., those involved with do-it-yourself projects). In cases where sentinel exposures
result in MOEs or excess cancer risks (ELCRs) greater than the benchmark or cancer risk lower than the
benchmark (i.e., risks were not identified), EPA did no further analysis because sentinel exposures
represent the highly exposed. A worker may be involved in multiple activities aside from their work
requirements that exposes them to asbestos that have varying occupational exposure scenarios. DIYers
may also perform multiple projects that exposes them to asbestos fibers. This would increase the overall
risk posed to these workers and DIYers. However, EPA is unable to determine the likelihood of a
worker or DIYer partaking in these multiple activities; therefore, EPA did not carry forward the
aggregate analysis into the risk determination. More information on how EPA characterized sentinel and
aggregate risks is provided in Section 5.3.4.
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For workers, cancer risks in excess of the benchmark (1 x 10~4) were indicated for all quantitatively
assessed COUs, with the exception of disposal, for high exposure potential workers or workers using
high-end exposures when PPE was not used. For higher exposure potential workers in the following
COUs, only the high-end exposure level indicated cancer and non-cancer risk: (1) Industrial/commercial
use - chemical substances in construction, paint, electrical, and metal products - construction and
building materials covering large surface areas - paper articles; metal articles; stone plaster, cement,
glass, and ceramic articles; and (2) Industrial/commercial use - chemical substances in furnishing,
cleaning, treatment care products - construction and building materials covering large surface areas -
fabrics, textiles, and apparel. EPA identified cancer risks in excess of the benchmark (1 x 10~4) for ONUs
for only the following COUs: (1) Industrial and commercial uses with chemical substances in
construction, paint, electrical, and metal products - machinery, mechanical appliances and
electrical/electronic articles; and (2) Industrial and commercial uses with chemical substances in
construction, paint, electrical, and metal products - other machinery, mechanical appliances and
electrical/electronic articles.
EPA also identified cancer risk from take-home exposures for all quantitatively assessed COUs. EPA
identified non-cancer risk for firefighters due to exposures from two occupational COUs: (1)
Industrial/commercial use - chemical substances in construction, paint, electrical, and metal products -
construction and building materials covering large surface areas - paper articles; metal articles; stone
plaster, cement, glass, and ceramic articles; and (2) Industrial/commercial use - chemical substances in
furnishing, cleaning, treatment care products - construction and building materials covering large
surface areas - fabrics, textiles, and apparel. In general, the chronic non-cancer risk at the high-end and
central tendency exposure level was identified for all quantitatively assessed COUs across all
populations (high exposure potential worker, low exposure potential worker, ONU, worker, and those
COUs where firefighters [both career and volunteer] where assessed).
EPA identified cancer and non-cancer risks for garment handlers who may handle asbestos-containing
garments and bystanders near those handling the asbestos-containing garments for all quantitatively
assessed COUs.
For general population exposed due to releases from occupational conditions of use, EPA considers a
cancer risk benchmark range of 1x 10~4 to 1 x 10 6. EPA identified cancer risk for general population in
the following five COUs:
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - construction and building materials covering large surface areas - paper articles;
metal articles; stone plaster, cement, glass, and ceramic articles;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - machinery, mechanical appliances, electrical/electronic articles;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - other machinery, mechanical appliances, electronic/electronic articles;
• Industrial/commercial use - chemical substances in furnishing, cleaning, treatment care products
- construction and building materials covering large surface areas - fabrics, textiles, and apparel;
and
• Industrial/commercial use - chemical substances in furnishing, cleaning, treatment care products
- Furniture & furnishings including stone, plaster, cement, glass, and ceramic articles; metal
articles; or rubber articles.
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EPA's estimates for workers and ONU risks for each occupational exposure scenario are presented in
Table 5-21, risk estimates for take-home exposures are presented in Table 5-23, and risk estimates for
general population are presented in Table 5-24.
For consumers (DIYers) and bystanders of consumer use EPA estimated cancer risks resulting from
inhalation exposures. For consumers and bystanders cancer risks in excess of the benchmark (1 x 10~6)
were indicated for three quantitatively assessed COUs: (1) Consumer use - chemical substances in
furnishing, cleaning, treatment care products - furniture and furnishings - stone, plaster, cement, glass,
and ceramic articles; metal articles; or rubber articles; (2) Consumer use - chemical substances in
construction, paint, electrical, and metal products - construction and building materials covering large
surface areas - paper articles; metal articles; stone, plaster, cement, glass, and ceramic articles; and (3)
Consumer use - chemical substances in construction, paint, electrical, and metal products - fillers and
putties. EPA's estimates for consumer and bystander risks for each consumer use exposure scenario are
presented in Table 5-23. For the COUs listed below, the Agency has limited data available and was not
able to quantify risks to human health and therefore cannot determine that these COUs contribute to the
unreasonable risk, at this time:
• Industrial/commercial use - chemical substances in products not described by other codes -
other (artifacts);
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - electrical batteries and accumulators;
• Industrial/commercial use - chemical substances in packaging, paper, plastic - packaging
(excluding food packaging) - rubber articles; plastic articles (hard); plastic articles (soft);
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
machinery, mechanical appliances, electrical/ electronic articles;
• Consumer use - chemical substances in products not described by other codes - other (artifacts);
• Consumer use - chemical substances in packaging paper, plastic, toys, hobby products -
packaging (excluding food packaging) - rubber articles; plastic articles (hard); plastic articles
(soft);
• Consumer use - chemical substances in construction, paint, electrical and metal products -
solvent-based/ water-based paint;
• Consumer use - chemical substances in construction, paint, electrical, and metal products -
construction and building materials covering large surface areas - paper articles; metal articles;
stone, plaster, cement, glass, and ceramic articles; and
• Consumer use - chemical substances in furnishing, cleaning, treatment care products -
construction and building materials covering large surface areas - fabrics, textiles, and apparel.
6.2.1.4 Unreasonable Risk in Occupational Settings
EPA is preliminarily determining that worker risk (including ONUs) for all COUs with quantified risk
estimates contribute to the unreasonable risk for asbestos due to cancer and non-cancer risks from
inhalation exposures. EPA is also preliminarily determining the two occupational COUs associated with
firefighters contribute to the unreasonable risk for asbestos due to non-cancer risks from inhalation
exposures. For workers, including ONUs, EPA consider exposures to asbestos for the entire 8-hour
workday for up to 250 days per year for 40 working years. Also, EPA is using an 8-hour time weighted
average (8-hour TWA) and short-term (30-minute) inhalation exposure estimates. The short-term
average daily concentration (ADC) estimates are calculated using the 30-minute exposure
concentrations, averaged with 7.5 hours at the full shift (i.e., 8-hour TWA) exposure concentrations.
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While the exposure scenarios in the risk evaluation did not assume compliance with existing federal
regulation, the monitoring data used may reflect the existing federal, state and local regulations requiring
proper management of asbestos-containing materials. Under the Asbestos Hazard Emergency Response
Act (AHERA) under Title II of TSCA, EPA issued regulations requiring local education agencies
(public school districts and non-profit private schools, including charter schools and schools affiliated
with religious institutions) to inspect their school buildings for asbestos, prepare asbestos management
plans and perform asbestos response actions. AHERA also required EPA to develop a model plan for
states for training and accrediting persons conducting asbestos inspections and corrective-action
activities at schools and public and commercial buildings.
Under the Clean Air Act, the asbestos National Emission Standards for Hazardous Air Pollutants
(NESHAPs) regulations specify work practices for asbestos to be followed during renovations and prior
to demolitions of all structures, installations, and buildings (excluding residential buildings that have
four or fewer dwelling units). And OSHA regulates asbestos through standards for the construction
industry, general industry, and shipyard employment sectors. These standards require exposure
monitoring, awareness training. When asbestos exposure is identified, employers are required to
establish regulated areas, controlling certain work practices, instituting engineering controls, use
administrative controls and, if needed, provide for the wearing of personal protective equipment. OSHA
standards also require proper handling of work clothing to prevent "take home" contaminated work
clothing. Risk estimates at the central tendency that show risks below the benchmark may include
situations where existing federal, state and local asbestos regulatory requirements required work
practices that reduced the release of asbestos fibers. EPA focused on the high-end risk estimates to
represent situations where workers, including persons hired to perform home renovation work, may not
be subject to existing asbestos regulatory requirements or follow work practices to reduce asbestos
exposure. However, there are situations where workers, including self-employed persons hired to
perform home renovation work, may not be subject to existing asbestos regulatory requirements, or do
not follow work practices to reduce asbestos exposure, or may not be aware that asbestos is present at
the worksite.
6.2.1.5 Unreasonable Risk for Take-Home Exposures
EPA is preliminarily determining that take-home exposure risks contribute to the unreasonable risk for
asbestos due to cancer and non-cancer risks from inhalation exposures.
To determine the unreasonable risk presented by asbestos, EPA considered the cancer inhalation
exposures for both garment handlers who may handle asbestos containing garments for high-intensity
exposure levels and bystanders; and chronic non-cancer inhalation exposures for both garment handlers
and bystanders. EPA estimates the yearly average concentration for each exposure scenario for cancer
and non-cancer risk estimates, taking into consideration the exposure point concentration (asbestos
fibers in the air), the exposure time (hours/day) over a 24-hour period, and the exposure frequency
(days/year) over 365 days. Section 5.1.2 provides a detailed description on how the Agency developed
the yearly average concentration for in take-home scenarios.
6.2.1.6 Unreasonable Risk to Consumers
EPA is preliminarily determining the consumer COUs quantitatively evaluated contribute to the
unreasonable risk for asbestos due to cancer and non-cancer risks from consumer DIYer and bystander
inhalation exposures.
EPA estimated both consumer and bystander activity-based exposures. The exposure can start at 16
years of age and because asbestos remains in the body (e.g., lungs) until the estimated life expectancy
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age of 78 years, the total exposure duration is 62 years of asbestos presence in the body after exposure
for DIY users. The exposure duration is 78 years for bystanders, since exposures can occur for younger
than 16 years of age. For repair activities, it was assumed that a DIY user may perform one repair or
renovation task where they may disturb asbestos containing material per year, as well as the length of
time spent on the task varies for low-end, high-end, and central tendency exposure estimates. For
removal activities, EPA reviewed the frequency of replacement for various home materials such as tiles
and roofing, but also considered the likelihood of consumers encountering legacy use ACM. Section
5.1.3.2 has a detailed description on how the Agency considered activity-based exposures.
More information on EPA's confidence in these risk estimates for inhalation and the uncertainties
associated with them can be found in Section 5.2.1.2 of this draft risk evaluation.
6.2.1.7 Unreasonable Risk to the General Population
EPA is preliminarily determining general population risks contribute to the unreasonable risk for
asbestos due to cancer and non-cancer risks from inhalation exposures. For cancer inhalation exposures
there are risks for the general population relative to the benchmark for people within 10 to 60 m from
the source, also known as the co-located distances, and 100 m from the source, defined as the general
population distances at low, central, and high-intensity exposure levels for several COUs. For purposes
of the risk determination, EPA is considering the 100 to 1,000 m risk estimates to determine that the
cancer and non-cancer risk from inhalation exposures from the disposal COU, including distribution for
disposal.
Exposure to the general population was estimated for the industrial and commercial releases per OES
and matched to each COU (see Section 5.1.4.1). These release estimates were then used to model
ambient air concentrations (see Section 5.1.4.2). Then the EPA modeled estimates for ambient air were
used to obtain inhalation exposures for general population. More information on the Agency's approach
and methodology for modeling and estimating general population exposures can be found in Section
5.1.4.1.
6.3 Unreasonable Risk for the Environment
6.3.1 Unreasonable Risk for the Environment Asbestos Part 2
Calculated risk quotients (RQs) can provide a risk profile by presenting a range of estimates for different
environmental hazard effects for different COUs. EPA was unable to calculate RQs for asbestos due to
limited exposure data. Based on the draft risk evaluation for asbestos—including the risk estimates, the
environmental effects of asbestos, the exposures, physical and chemical properties of asbestos, and
consideration of uncertainties—EPA is preliminarily determining that it did not identify risk of injury to
the environment that would contribute to the unreasonable risk determination for asbestos. Similar to the
Part 1 risk evaluation, EPA concluded that there is very limited potential for asbestos exposures for
aquatic- or sediment-dwelling organisms. EPA finds that asbestos does not present an unreasonable risk
to aquatic or terrestrial species. See Section 4.2 for more information on environmental hazards and the
methodology for assessment of aquatic and terrestrial species.
6.4 Additional Information Regarding the Basis for the Unreasonable Risk
Determination
Table 6-1 through Table 6-4 summarize the basis for this draft unreasonable risk determination of injury
to human health and the environment presented in this draft asbestos risk evaluation. In these tables, a
checkmark (S) indicates how the COU contributes both to the unreasonable risk by identifying the type
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of effect (e.g., human health or the environment) and the exposure route to the population that results in
such contribution. Please note that not all COUs, exposure routes, or populations evaluated are included
in the table. The table only includes the relevant exposure route, or the population that supports the
conclusion that the COU contributes to the asbestos unreasonable risk determination. As explained in
Section 6.2, for this draft unreasonable risk determination, EPA considered the effects of asbestos to
human health at the central tendency and high-end, as well as effects of asbestos to human health and
the environment from the exposures associated from the COU, risk estimates, and uncertainties in the
analysis. See Sections 5.3.2.1, 5.3.2.2, 5.3.2.3, and 5.3.2.4 of this draft part 2 risk evaluation for a
summary of risk estimates.
6.4.1 Additional Information about COUs Characterized Qualitatively
EPA did not have enough data to calculate risk estimates for all COUs, and EPA characterized the risk
by integrating limited amounts of reasonably available information in a qualitative characterization.
While the Agency is concluding that (1) asbestos as a chemical substance presents unreasonable risk to
human health; and (2) at this time, EPA does not have enough information to quantify with enough
weight of scientific evidence how much of the unreasonable risk of asbestos to consumers and
bystanders may be contributed by certain product types or product examples shown in Table 3-5.
For products where quantitative information was not available in the literature, exposure and risk
potential to populations identified in this draft risk evaluation are discussed qualitatively in Appendix H,
or in Appendix E describing the environmental releases and occupational exposure assessment. For
some of the OESs evaluated quantitatively, there are activities described in those scenarios where the
product/article is not disturbed or replaced (or both), or there is other information indicating that the
specific activity will not contribute to the unreasonable risk of asbestos. Therefore, for the COUs below,
EPA has explained that the risk estimates of the exposure scenario do not apply, and EPA is
preliminarily determining the COUs do not contribute to the unreasonable risk of asbestos:
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - fillers and putties;
• Industrial/commercial use - chemical substances in construction, paint, electrical, and metal
products - solvent based/water based paint;
• Industrial/commercial use - chemical substances in products not described by other codes -
other (aerospace applications): based on the description of activities related to aerospace
applications;
• Industrial/ commercial use - mining of non-asbestos commodities - mining of non-asbestos
commodities: based on data and information from MSHA and stakeholders, EPA has determined
that exposure to asbestos is unlikely;
• Industrial/ commercial use - laboratory chemicals - laboratory chemicals: based on EPA
analysis of vermiculite products, EPA does not expect any significant asbestos releases or
occupational exposures;
• Industrial/commercial use - chemical substances in automotive, fuel, agriculture, outdoor use
products - lawn and garden care products: based on EPA analysis of vermiculite products, EPA
does not expect any significant asbestos releases or occupational exposures; and
• Consumer use - chemical substances in automotive, fuel, agriculture, outdoor use products -
lawn and garden care products: based on EPA analysis of vermiculite products, EPA does not
expect any significant asbestos exposures to consumers.
For the consumer COU of toys intended for childrens use (and child dedicated articles), including
fabrics, textiles, and apparel; or plastic articles (hard) qualitative information was used for toys (mineral
kits and crayons). The Agency preliminarily finds that the COU does not contribute to unreasonable risk
Page 200 of 405
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4944 to consumers or bystanders based on exposure information about crayons; however, the Agency was
4945 unable to determine whether use of mineral kits contributes to unreasonable risk and therefore cannot
4946 determine that this COU contributes to the unreasonable risk (see Appendix H. 1.3). For other consumer
4947 COUs, quantitative risk estimates were supplemented with qualitative exposure assessments for certain
4948 product types and examples.
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4949 Table 6-1. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 1 Occupational CPUs)
Life Cycle
Stage
Category
Population
Human Health Effects (Chronic Cancer)
Central Tendency
High-Enda
8-Hour TWA
Short-Term
8-Hour TWA
Short-Term
Processing
Diaphragms in chlor-alkali industry
Workers
~
V
V
ONUs
N/A
•/
N/A
Sheet gaskets in chemical production
Workers
~
~
V
V
ONUs
•/
V
Industrial Use
Sheet gaskets in chemical production
Workers
•/
•/
V
ONUs
~
V
V
V
Diaphragms in chlor-alkali industry
Workers
S
Y
V
ONUs
N/A
Y
N/A
Brake blocks in oil industry
Workers
~
N/A
N/A
N/A
ONUs
~
N/A
N/A
N/A
Industrial/
Commercial use
Aftennarket automotive brakes/linings
Workers
V
~
V
S
ONUs
Other vehicle friction products (excludes
NASA aircraft use)
Workers
S
V
V
V
ONUs
Other gaskets
Workers
V
N/A
V
N/A
ONUs
V
N/A
V
N/A
Disposal
Brake blocks in oil industry
Workers
S
N/A
N/A
N/A
ONUs
S
N/A
N/A
N/A
Aftennarket automotive brakes/linings
Workers
S
V
¦/
V
ONUs
Other vehicle friction products (excludes
NASA aircraft use)
Workers
V
V
V
ONUs
Other gaskets
Workers
S
N/A
¦/
N/A
ONUs
S
N/A
¦/
N/A
11 See Sections 6.2.1.2 and 6.2.1.3 for discussion of central tendency vs. hig
N/A = not assessed
l-end.
4950
4951
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4952 Table 6-2. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 1 Consumer CPUs)
Life Cycle
Stage
Category
Population
Human Health Effects (Chronic Cancer)
Central Tendency
High-En dfl
Consumer
Use
Aftennarket automotive brakes/linings
Consumers
~
V
Bystander
V
V
Other gaskets
Consumers
V
V
Bystander
V
V
Disposal
Aftennarket automotive brakes/linings
Consumers
V
V
Bystander
V
V
Other gaskets
Consumers
V
V
Bystander
S
V
" See Sections 6.2.1.2 and 6.2.1.3 for discussion of central tendency vs. high-end.
4953
4954
Table 6-3. Supporting Basis for t
he Unreasonable Risk I
letermination for Human Health (Part 2 Occupational COUs)
Life Cycle
Stage
Category
Subcategory
Population
Chronic Non-cancer
(8-hour TWA)
Cancer
(8-hour TWA)
Industrial/
Commercial
Uses
Chemical
substances in
construction,
paint, electrical,
and metal
products
Construction and building
materials covering large
surface areas, including
paper articles; metal
articles; stone, plaster,
cement, glass, and
ceramic articles
High Exposure Potential Worker
~
~
Low Exposure Potential Worker
V
ONU
S
Firefighters (Career)
S
Firefighters (Volunteer)
S
Take Home - User Handler
V
~
Take Home - Bystander
S
~
Take Home - User Handler (Firefighting
Career)
~
Take Home - Bystander (Firefighting
Career)
~
General Population
~
General Population From Firefighting or
Other Disaster Response
V
Machinery, mechanical
appliances,
electrical/electronic
articles
Worker
S
V
ONU
~
V
Take Home - User Handler
~
V
Take Home - Bystander
~
V
General Population
~
V
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Life Cycle
Stage
Category
Subcategory
Population
Chronic Non-cancer
(8-hour TWA)
Cancer
(8-hour TWA)
Other machinery,
mechanical appliances,
electronic/electronic
articles
Worker
V
~
ONU
S
~
Take Home - User Handler
S
~
Take Home - Bystander
V
~
General Population
S
~
Industrial/
Commercial
Uses
Chemical
substances in
furnishing,
cleaning,
treatment care
products
Construction and building
materials covering large
surface areas, including
fabrics, textiles, and
apparel
High Exposure Potential Worker
S
~
Low Exposure Potential Worker
~
ONU
~
Firefighters (Career)
S
Firefighters (Volunteer)
S
Take Home - User Handler
S
V
Take Home - Bystander
V
V
Take Home - User Handler (Firefighting
Career)
V
Take Home - Bystander (Firefighting
Career)
V
General Population
V
General Population From Firefighting or
Other Disaster Response
V
Furniture & furnishings
including stone, plaster,
cement, glass, and
ceramic articles; metal
articles; or rubber articles
High Exposure Potential Worker
S
S
Low Exposure Potential Worker
S
ONU
V
Take Home - User Handler
V
S
Take Home - Bystander
S
S
General Population
S
S
Disposal,
Including
Distribution for
Disposal
Disposal,
including
distribution for
disposal
Disposal, including
distribution for disposal
Worker
S
ONU
S
Take Home - User Handler
S
V
Take Home - Bystander
S
V
4956
4957
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4958 Table 6-4. Supporting Basis for the Unreasonable Risk Determination for Human Health (Part 2 Consumer DIY CPUs)
Life Cycle Stage
Category
Subcategory
Population
Chronic Non-cancer
Cancer
Consumer Use
Chemical substances in
construction, paint,
electrical, and metal
products
Construction and building
materials covering large surface
areas: paper articles; metal
articles; stone, plaster, cement,
glass and ceramic articles
User (Consumer DIYer)
~
~
Bystander
Chemical substances in
construction, paint,
electrical, and metal
products
Fillers and putties
User (Consumer DIYer)
~
~
Bystander
Chemical substances in
furnishing, cleaning,
treatment care products
Furniture and furnishings,
including stone, plaster, cement,
glass, and ceramic articles; metal
articles; or rubber articles
User (Consumer DIYer)
~
Bystander
DIY = do-it-yourself
4959
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Weir. FW; Tolar. G; Meraz. LB. (2001). Characterization of vehicular brake service personnel exposure
to airborne asbestos and particulate. Appl Occup Environ Hyg 16: 1139-1146.
http://dx.doi.org/10.1080/104732201274Q2
WHO. (2014). Chrysotile asbestos. Geneva, Switzerland.
http://www.who.int/ipcs/assessment/public health/chrysotile asbestos summary.pdf
Wilson. R; McConnell. EE: Ross. M; Axten. CW: Nolan. RP. (2008). Risk assessment due to
environmental exposures to fibrous particulates associated with taconite ore. Regul Toxicol
Pharmacol 52: S232-S245. http://dx.doi.Org/10.1016/i.vrtph.2007.l 1.005
Witek. J: Psiuk. B; Naziemiec. Z; Kusiorowski. R. (2019). Obtaining an artificial aggregate from
cement-asbestos waste by the melting technique in an arc-resistance furnace. Fibers 7.
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WST. (2019). Asbestos in mineral kits [Website], https://worksafe.tas.gov.au/topics/Health-and-
Safetv/safetv-alerts/asbestos-in-mineral-kits
Yoon. S: Yeom. K; Kim. Y; Park. B; Park. J: Kim. H; Jeong. H; Roh. Y. (2020). Management of
naturally occurring asbestos area in Republic of Korea. Environmental and Engineering
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Zhang. YL; Byeon. HS: Hong. WH; Cha. GW: Lee. YH; Kim. YC. (2021). Risk assessment of asbestos
containing materials in a deteriorated dwelling area using four different methods. J Hazard Mater
410: 124645. http://dx.doi.Org/10.1016/i.ihazmat.2020.124645
Zhong. Q: Liao. ZT; Qi. LJ; Zhou. ZY. (2019). Black Nephrite Jade from Guangxi, Southern China.
Gems & Gemology 55: 198-215. http://dx.doi.Org/10.5741/GEMS.55.2.198
Zielina. M; Dabrowski. W: Lang. T. (2007). Assessing the risk of corrosion of asbestos-cement pipes in
Krakow's water supply network. Environ Protect Eng 33: 17-26.
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APPENDICES
Appendix A ABBREVIATIONS, ACRONYMS, AND SELECT
GLOSSARY
A.l Abbreviations
ACGM
American Conference of Governmental Industrial Hygienists
ACM
Asbestos-containing material(s)
ACH
Air changes per hour
ADC
Average daily concentration
AERMOD
American Meteorological Society/EPA Regulatory Model
AF
Assessment factor
AHERA
Asbestos Hazard Emergency Response Act
ATSDR
Agency for Toxic Substances and Disease Registry
BCF
Bioconcentration factor
BLS
Bureau of Labor Statistics
BMR
Benchmark response
CAS
Chemical Abstracts Service
CASRN
Chemical Abstracts Service Registry Number
CDR
Chemical Data Reporting
CEHD
Chemical Exposure Health Data
CERCLA
Comprehensive Environmental Response, Compensation and Liability Act
CFR
Code of Federal Regulations
ChV
Chronic value
coc
Concentration(s) of concern
CPSA
Consumer Product Safety Act
CPSC
Consumer Product Safety Commission
CWA
Clean Water Act
DIY
Do-it-yourself
DMR
Discharge Monitoring Report
ECEL
Existing chemical exposure limit
EPA
Environmental Protection Agency
EPCRA
Emergency Planning and Community Right-to-Know Act
ESD
Emission Scenario Document
EU
European Union
FDA
Food and Drug Administration
FFDCA
Federal Food, Drug, and Cosmetic Act
GWB
Gypsum wallboard
HAP
Hazardous Air Pollutant
HERO
Health and Environmental Research Online (Database)
HHE
Health hazard evaluation
HMTA
Hazardous Materials Transportation Act
IARC
International Agency for Research on Cancer
IIOAC
Integrated Indoor-Outdoor Air Calculator
IDLH
Immediately Dangerous to Life and Health
IRIS
Integrated Risk Information System
IUR
Inhalation unit risk
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6000
6001
6002
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6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
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LAA
Libby Amphibole Asbestos
LOD
Limit of detection
LOEC
Lowest-observed-effect-concentration
LTL
Less-than-lifetime
MCL
Maximum Contaminant Level
MOA
Mode of action
MUC
Maximum Use Concentration (OSHA)
NAICS
North American Industry Classification System
ND
Non-detect
NEI
National Emissions Inventory
NESHAP
National Emission Standards for Hazardous Air Pollutants
NICNAS
National Industrial Chemicals Notification and Assessment Scheme
NIOSH
National Institute for Occupational Safety and Health
NITE
National Institute of Technology and Evaluation
NOEC
No-observed-effect-concentration
NPDES
National Pollutant Discharge Elimination System
NPDWR
National Primary Drinking Water Regulation
NRC
National Response Center
NTP
National Toxicology Program
NWIS
National Water Information System
OCSPP
Office of Chemical Safety and Pollution Prevention
OECD
Organisation for Economic Co-operation and Development
OEL
Occupational exposure limit
OES
Occupational exposure scenario
ONU
Occupational non-user
OPPT
Office of Pollution Prevention and Toxics
OSHA
Occupational Safety and Health Administration
PBZ
Personal breathing zone
PCM
Phase contrast microscopy
PCME
PCM-equivalent
PECO
Population, exposure, comparator, and outcome
PEL
Permissible exposure limit (OSHA)
PESS
Potentially exposed or susceptible subpopulations
PLM
Polarized light microscopy
POD
Point of departure
POTW
Publicly owned treatment works
PPE
Personal protective equipment
RCRA
Resource Conservation and Recovery Act
REL
Recommended Exposure Limit
RF
Reduction factor
RQ
Risk quotient
RTR
Risk and technology review (EPA program)
see
Source classification code
SDWA
Safe Drinking Water Act
SEM
Scanning electron microscopy
SIPP
Survey of Income and Program Participation (U.S. Census)
SEG
Similar exposure group
SOC
Standard Occupational Classification
STORET
STOrage and RETrieval and Water Quality (data warehouse)
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6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
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SUSB
Statistics of U.S. Businesses (U.S. Census)
TEM
Transmission electron microscopy
TLV
Threshold Limit Value
TRI
Toxics Release Inventory
TRV
Toxicity reference value
TSCA
Toxic Substances Control Act
TWA
Time-weighted average
TWF
Time-weighted factor
U.S.
United States
USGS
United States Geological Survey
WHO
World Health Organization
WTC
World Trade Center
A.2 Glossary of Select Terms
Best available science (40 CFR 702.33): "means science that is reliable and unbiased. Use of best
available science involves the use of supporting studies conducted in accordance with sound and
objective science practices, including, when available, peer reviewed science and supporting studies and
data collected by accepted methods or best available methods (if the reliability of the method and the
nature of the decision justifies use of the data). Additionally, EPA will consider as applicable:
(1) The extent to which the scientific information, technical procedures, measures, methods,
protocols, methodologies, or models employed to generate the information are reasonable for and
consistent with the intended use of the information;
(2) The extent to which the information is relevant for the Administrator's use in making a decision
about a chemical substance or mixture;
(3) The degree of clarity and completeness with which the data, assumptions, methods, quality
assurance, and analyses employed to generate the information are documented;
(4) The extent to which the variability and uncertainty in the information, or in the procedures,
measures, methods, protocols, methodologies, or models, are evaluated and characterized; and
(5) The extent of independent verification or peer review of the information or of the procedures,
measures, methods, protocols, methodologies or models."
Condition of use (COU) (15 U.S.C. 2602(4)): "means the circumstances, as determined by the
Administrator, under which a chemical substance is intended, known, or reasonably foreseen to be
manufactured, processed, distributed in commerce, used, or disposed of."
Margin of exposure (MOE) (U.S. EPA. 2002): "a numerical value that characterizes the amount of
safety to a toxic chemical-a ratio of a toxicological endpoint (usually a NOAEL [no observed adverse
effect level]) to exposure. The MOE is a measure of how closely the exposure comes to the NOAEL."
Mode of action (MOA) (U.S. EPA. 2000b): "a series of key events and processes starting with
interaction of an agent with a cell, and proceeding through operational and anatomical changes causing
disease formation."
Point of departure (POD) (U.S. EPA. 2002): "dose that can be considered to be in the range of
observed responses, without significant extrapolation. A POD can be a data point or an estimated point
that is derived from observed dose-response data. A POD is used to mark the beginning of extrapolation
to determine risk associated with lower environmentally relevant human exposures."
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Potentially exposed or susceptible subpopulations (PESS) (15 U.S.C. 2602(12)): "means a group of
individuals within the general population identified by the Agency who, due to either greater
susceptibility or greater exposure, may be at greater risk than the general population of adverse health
effects from exposure to a chemical substance or mixture, such as infants, children, pregnant women,
workers, or the elderly."
Reasonably available information (40 CFR 702.33): "means information that EPA possesses or can
reasonably generate, obtain, and synthesize for use in risk evaluations, considering the deadlines
specified in TSC A section 6(b)(4)(G) for completing such evaluation. Information that meets the terms
of the preceding sentence is reasonably available information whether or not the information is
confidential business information, that is protected from public disclosure under TSCA section 14."
Routes (40 CFR 702.33): "means the particular manner by which a chemical substance may contact the
body, including absorption via ingestion, inhalation, or dermally (integument)."
Sentinel exposure (40 CFR 702.33): "means the exposure from a single chemical substance that
represents the plausible upper bound of exposure relative to all other exposures within a broad category
of similar or related exposures."
Weight of scientific evidence (40 CFR 702.33): "means a systematic review method, applied in a
manner suited to the nature of the evidence or decision, that uses a pre-established protocol to
comprehensively, objectively, transparently, and consistently, identify and evaluate each stream of
evidence, including strengths, limitations, and relevance of each study and to integrate evidence as
necessary and appropriate based upon strengths, limitations, and relevance."
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6119 Appendix B REGULATORY AND ASSESSMENT HISTORY
6120
6121 B.l Federal Laws and Regulations
6122 The chemical substance, asbestos, is subject to federal and state laws and regulations in the United
6123 States (TableApx B-l and TableApx B-2). Regulatory actions by other governments, tribes, and
6124 international agreements applicable to asbestos are listed in Table Apx B-3. A history of asbestos
6125 ssessments by EPA and other organizations is provided in Table Apx B-4. Assessment History of
6126 Asbestos.
6127
6128 Table Apx B-l. Federal Laws and Regulations
Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
EPA statues/regulations
TSCA - section 5(a)
Directs EPA to determine that a use of a
chemical substance is a "significant new
use." EPA must make this determination by
rule after considering all relevant factors,
including those listed in TSCA section
5(a)(2). Once EPA determines that a use of
a chemical substance is a significant new
use, TSCA section 5(a)(1) requires persons
to submit a significant new use notice
(SNUN) to EPA at least 90 days before they
manufacture (including import) or process
the chemical substance for that use. TSCA
prohibits the manufacturing (including
importing) or processing from commencing
until EPA has conducted a review of the
notice, made an appropriate determination
on the notice, and taken such actions as are
required in association with that
determination.
A significant new use rule for asbestos
was issued to ensure that any
discontinued uses of asbestos cannot re-
enter the marketplace without EPA
review, closing a loophole in the
regulatory regime for asbestos (84 FR
17345, April 25, 2019)
TSCA - section 6(b)
Directs EPA to promulgate regulations to
establish processes for prioritizing chemical
substances and conducting risk evaluations
on priority chemicals substances. In the
meantime, EPA was required to identify and
begin risk evaluations on 10 chemical
substances drawn from the 2014 update of
the TSCA Work Plan for Chemical
Assessments.
Asbestos is one of the 10 chemical
substances on the initial list to be
evaluated for unreasonable risk of
injury to health or the environment (81
FR 91927, December 19, 2016).
TSCA - section 8(a)
The TSCA section 8(a) CDR Rule requires
manufacturers (including importers) to give
EPA basic exposure-related information on
the types, quantities and uses of chemical
substances produced domestically and
imported into the United States.
TSCA section 8(a) generally authorizes
EPA to promulgate rules that require
entities, other than small manufacturers
(including importers) or processors, who
Asbestos manufacturing (including
importing), processing, and use
information is reported under the CDR
rule (76 FR 50816, August 16, 2011).
A rule under TSCA section 8(a)(1)
requiring certain persons who
manufactured (including imported) or
processed asbestos and asbestos-
containing articles (including as an
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Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
manufacture (including import) or process,
chemical substance to maintain certain
records and submit such reports as the EPA
Administrator may reasonably require.
impurity) in the last four years to report
certain exposure-related information,
including quantities of asbestos
manufactured or processed, types of
use, and employee data (88 FR 47782,
July 25, 2023)"
TSCA - section 8(b)
EPA must compile, keep current and
publish a list (the TSCA Inventory) of each
chemical substance manufactured,
processed or imported in the United States.
Asbestos was on the initial TSCA
Inventory and therefore was not subject
to EPA's new chemicals review process
under TSCA section 5 (60 FR 16309,
March 29, 1995).
TSCA - section 8(d)
Provides EPA with authority to issue rules
requiring producers, importers, and (if
specified) processors of a chemical
substance or mixture to submit lists and/or
copies of ongoing and completed,
unpublished health and safety studies.
One submission received in 2001 (U.S.
EPA, Chemical Data Access Tool.
Accessed April 24, 2017).
TSCA - section 8(e)
Manufacturers (including importers),
processors, and distributors must
immediately notify EPA if they obtain
information that supports the conclusion
that a chemical substance or mixture
presents a substantial risk of injury to health
or the environment.
Four submissions received 1992, 1993,
1994, and 1996 (U.S. EPA, ChemView.
Accessed May 8, 2023).
Asbestos Hazard
Emergency Response
Act (AHERA), 1986
TSCA Subchapter II:
Asbestos Hazard
Emergency Response
15 U.S.C.2641-2656
Defines asbestos as the asbestiform varieties
of chrysotile (serpentine), crocidolite
(riebeckite), amosite (cummingtonite-
grunerite), anthophyllite, tremolite or
actinolite.
Requires local education agencies (i.e.,
school districts) to inspect school buildings
for asbestos and submit asbestos
management plans to appropriate state;
management plans must be publicly
available, and inspectors must be trained
and accredited.
Tasked EPA to develop an asbestos Model
Accreditation Plan (MAP) for states to
establish training requirements for asbestos
professionals who do work in school
buildings and also public and commercial
buildings.
Asbestos-Containing Materials in
Schools Rule (per AHERA), 1987 40
CFR Part 763, subpart E
Requires local education agencies to use
trained and accredited asbestos
professionals to identify and manage
asbestos-containing building material
and perform asbestos response actions
(abatements) in school buildings.
Asbestos:
Manufacture,
Importation,
Processing, and
Distribution in
Commerce
Prohibitions; Final
Rule (1989)
EPA issued a final rule under section 6
of TSCA banning most asbestos-
containing products.
In 1991, this rule was vacated and
remanded by the Fifth Circuit Court of
Appeals. As a result, most of the
original ban on the manufacture,
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Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
40 CFR part 763,
subpart I
importation, processing, or distribution
in commerce for the majority of the
asbestos-containing products originally
covered in the 1989 final rule was
overturned. The following products
remain banned by rule under TSCA:
• Corrugated paper
• Rollboard
• Commercial paper
• Specialty paper
• Flooring felt
In addition, the regulation continues to
ban the use of asbestos in products that
have not historically contained asbestos,
otherwise referred to as "new uses" of
asbestos (Defined by 40 CFR 763.163
as "commercial uses of asbestos not
identified in §763.165 the manufacture,
importation or processing of which
would be initiated for the first time after
August 25, 1989/').
Asbestos Worker
Protection Rule, 2000
40 CFR part 763,
subpart G
Extends OSHA standards to public
employees in states that do not have an
OSHA approved worker protection
plan.
Asbestos Information
Act, 1988
15 U.S.C. 2607(f)
Helped to provide transparency and
identify the companies making certain
types of asbestos-containing products
by requiring manufacturers to report
production to the EPA.
Asbestos School
Hazard Abatement Act
(ASHAA), 1984 and
Asbestos School
Hazard Abatement
Reauthorization Act
(ASHARA), 1990
20 U.S.C. 401 let seq.
Provided funding for and established an
asbestos abatement loan and grant
program for school districts and
ASHARA further tasked EPA to update
the MAP asbestos worker training
requirements.
Emergency Planning
and Community
Right-to-Know Act
(EPCRA) - section
313
Requires annual reporting from facilities in
specific industry sectors that employ 10 or
more full-time equivalent employees and
that manufacture, process or otherwise use a
TRI-listed chemical in quantities above
threshold levels. A facility that meets
reporting requirements must submit a
reporting form for each chemical for which
it triggered reporting, providing data across
a variety of categories, including activities
and uses of the chemical, releases and other
waste management (e.g., quantities
recycled, treated, combusted) and pollution
prevention activities (under section 6607 of
Under section 313, Toxics Release
Inventory (TRI), requires reporting of
environmental releases of friable
asbestos at a concentration level of
0.1%.
Friable asbestos is designated as a
hazardous substance subject to an
Emergency Release Notification at 40
CFR 355.40 with a reportable quantity
of 1 lb.
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Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
the Pollution Prevention Act). These data
include on- and off-site data as well as
multimedia data (i.e., air, land, and water).
Clean Air Act, 1970
42 U.S.C. 7401 etseq.
Asbestos National
Emission Standard for
Hazardous Air
Pollutants (NESHAP),
1973
40 CFRpart 61, subpart M
Specifies demolition and renovation
work practices involving asbestos in
buildings and other facilities (but
excluding residences with 4 or fewer
dwelling units single family homes).
Requires building owner/operator notify
appropriate state agency of potential
asbestos hazard prior to
demolition/renovation.
Banned spray-applied surfacing
asbestos-containing material for
fireproofing/insulating purposes in
certain applications.
Requires that asbestos-containing waste
material from regulated activities be
sealed in a leak-tight container while
wet, labeled, and disposed of properly
in a landfill qualified to receive asbestos
waste.
Clean Water Act
(CWA), 1972 33
U.S.C. 1251 et seq
Toxic pollutant subject to effluent
limitations per section 1317. Asbestos is
a Priority Pollutant.
Safe Drinking Water
Act (SDWA), 1974 42
U.S.C. 300f et seq
Asbestos Maximum Contaminant Level
(MCL) 7 million fibers/L (longer than
10 (im).
Resource
Conservation and
Recovery Act
(RCRA), 1976 42
U.S.C. 6901 et seq.
40 CFR 239-282
Asbestos is subject to solid waste
regulation when discarded; NOT
considered a hazardous waste.
Comprehensive
Environmental
Response,
Compensation and
Liability Act
(CERCLA), 1980 42
U.S.C. 9601 et seq.
40 CFRpart 302.4 - Designation of
Hazardous Substances and Reportable
Quantities
13 Superfund sites containing asbestos,
9 of which are on the National Priorities
List (NPL) Reportable quantity of
friable asbestos is 1 lb.
Other federal statutes/regulations
Occupational Safety
and Health
Administration
(OSHA):
Public Law 91-596
Occupational Safety
and Health Act, 1970
Asbestos General Standard 29 CFR 1910
Asbestos Shipvard Standard 29 CFR 1915
Asbestos Construction Standard 29 CFR
1926
Employee permissible exposure limit
(PEL) is 0.1 fibers per cubic centimeter
(f/cc) as an 8-hour, time- weighted
average (TWA) and/or the excursion
limit (1.0 f/cc as a 30-minute TWA).
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Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
Consumer Product
Safety Act
Federal Hazardous
Substances Act
(FHSA) 16 CFR 1500
The CPSA provides the Consumer Product
Safety Commission with authority to recall
and ban products under certain
circumstances.
The FHSA requires certain hazardous
household products to have warning labels.
It also gives CPSC the authority to regulate
or ban a hazardous substance, and toys or
other articles intended for use by children,
under certain circumstances.
Consumer patching compounds and
artificial ash and embers containing
respirable freeform asbestos are banned
as hazardous products under the CPSA.
(16 CFR 1304 & 1305)
General-use garments containing
asbestos are banned as a hazardous
substance under the FHSA (16 CFR
1500.17(a))
Federal Food and
Cosmetics Act
(FFDCA)
Provides the FDA with authority to oversee
the safety of food, drugs and cosmetics.
Prohibits the use of asbestos-containing
filters in pharmaceutical manufacturing,
processing and packing.
21 CFR 211.72
Mine Safety and
Health Administration
(MSHA)
Surface Mines 30 CFR part 56. subpart
D
Underground Mines 30 CFR part 57.
subpart D
Federal Hazardous
Materials
Transportation Act
(HMTA)
Section 5103 of the Act directs the
Secretary of Transportation to:
• Designate material (including an
explosive, radioactive material,
infectious substance, flammable or
combustible liquid, solid or gas, toxic,
oxidizing or corrosive material, and
compressed gas) as hazardous when the
Secretary determines that transporting
the material in commerce may pose an
unreasonable risk to health and safety
or property.
• Issue regulations for the safe
transportation, including security, of
hazardous material in intrastate,
interstate, and foreign commerce.
Asbestos is listed as a hazardous
material with regard to transportation
and is subject to regulations prescribing
requirements applicable to the shipment
and transportation of listed hazardous
materials. 49 CFR part
172.101 Appendix A.
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6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
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B.2 State Laws and Regulations
Pursuant to AHERA, states have adopted through state regulation the EPA's Model Accreditation Plan
(MAP) for asbestos abatement professionals who do work in schools and public and commercial
buildings. Thirty-nine states have EPA-approved MAP programs and 12 states have also applied to and
received a waiver from EPA to oversee implementation of the Asbestos-Containing Materials in Schools
Rule pursuant to AHERA. States also implement regulations pursuant to the Asbestos NESHAP
regulations or further delegate those oversight responsibilities to local municipal governments. While
federal regulations set national asbestos safety standards, states have the authority to impose stricter
regulations. As an example, many states extend asbestos federal regulations—such as asbestos
remediation by trained and accredited professionals, demolition notification, and asbestos disposal—to
ensure safety in single-family homes. Thirty states require firms hired to abate asbestos in single family
homes to be licensed by the state. Nine states mandate a combination of notifications to the state,
asbestos inspections, or proper removal of asbestos in single family homes. Some states have regulations
completely independent of the federal regulations. For example, California and Washington regulate
products containing asbestos. Both prohibit use of more than 0.1 percent of asbestos in brake pads and
require laboratory testing and labeling.
Table Apx B-2 includes a non-exhaustive list of state regulations that are independent of the federal
AHERA and NESHAP requirements that states implement.
Table Apx B-2. State Laws and Regulations
State Actions
Description of Action
California
Asbestos is listed on California's Candidate Chemical List as a carcinoaen. Under
California's Propositions 65. businesses are required to warn Californians of the
presence and danger of asbestos in products, home, workplace and environment.
California Brake Friction
Material Requirements
(Effective 2017)
Division 4.5, California Code of Regulations, Title 22 Chapter 30
Sale of any motor vehicle brake friction materials containing more than 0.1%
asbestiform fibers by weight is prohibited. All brake pads for sale in the state of
California must be laboratory tested, certified and labeled by the manufacturer.
Massachusetts
Massachusetts Toxics Use Reduction Act (TURA)
Requires companies in Massachusetts to provide annual pollution reports and to
evaluate and implement pollution prevention plans. Asbestos is included on the
Complete List of TURA Chemicals - March 2016.
Minnesota
Toxic Free Kids Act Minn. Stat. 2010 116.9401 - 116.9407
Asbestos is included on the 2016 Minnesota Chemicals of Hish Concern List as a
known carcinogen.
New Jersey
New Jersev Right to Know Hazardous Substances
The state of New Jersey identifies hazardous chemicals and products. Asbestos is
listed as a known carcinogen and talc containing asbestos is identified on the Right
to Know Hazardous Substances list.
Rhode Island
Rhode Island Air Resources - Air Toxics Air Pollution Control Regulation No. 22
Establishes acceptable ambient air levels for asbestos.
Washington
Better Brakes Law (Effective 2015) Chapter 70.285 RCWBrake Friction Material
Prohibits the sale of brake pads containing more than 0.1% asbestiform fibers (by
weight) in the state of Washington and requires manufacturer certification and
package/product labeling.
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State Actions
Description of Action
Requirement to Label Building. Materials that Contain Asbestos Chapter 70.310
RCW
Building materials that contain asbestos must be clearly labeled as such by
manufacturers, wholesalers, and distributors.
6150 B.3 International Laws and Regulations
6151
6152 TableApx B-3. Regulatory Actions by Other Governments, Tribes, and International
Country/
Organization
Requirements and Restrictions
European Union
The European Union (EU) will prohibit the use of asbestos in the chlor-alkali
industry bv 2025 (Regulation(EC) No 1907/2006 of the European Parliament
and of the Council. 18 December 2006).
Otherwise, under EU regulations, the placing on the market and use of chrysotile
fibers and products containing these fibers added intentionally are already
prohibited pursuant to Directive 1999/77/ E.C. of 26.7.1999. The use of products
containing asbestos fibers that were already installed and/or in service before the
implementation date of Directive 1999/77/ EC continues to be authorized until
such products are disposed of or reach the end of their service life. However,
Member States may prohibit the use of such products before they are disposed of
or reach the end of their service life (Regulatory Status of chrvsotile asbestos in
the EU).
The emissions and release of asbestos is regulated, and construction materials
containing asbestos are classified as hazardous waste. Concerning the safety of
workers, EU regulations stipulate that employers shall ensure that no worker is
exposed to an airborne concentration of asbestos (including chrysotile) in excess
of 0.1 fibers per cm3 as an 8-hour TWA (Regulatory Status of chrvsotile asbestos
in the EU).
Canada
Canada banned asbestos in 2018.
Prohibition of Asbestos and Products Containing Asbestos Regulations:
SOR/2018-196 (Canada Gazette. Part II. Volume 152. Number 21).
UNEP Rotterdam
Convention
The Conference of Parties is considering a recommendation from the Chemical
Review Committee to list chrvsotile asbestos in Annex III to the Rotterdam
Convention. Annex III chemicals require prior informed consent for importation.
UNEP Basel Convention
Under the Basel Convention. Asbestos (dust and fibres) is designated a
hazardous waste. Listed codes Y36 (Annex 1) and A2050 (Annex VIII). Among
its provisions, the Convention restricts the import and export of hazardous waste
and requires parties to the convention to appropriate measures to ensure the
environmentally sound management of hazardous waste.
World Health Organization
(WHO)
The World Health Assembly resolution 60.26 reauests WHO to carrv out a
global campaign for the elimination of asbestos-related diseases "...bearing in
mind a differentiated approach to regulating its various forms - in line with the
relevant international legal instruments and the latest evidence for effective
interventions...
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Country/
Organization
Requirements and Restrictions
Algeria, Argentina,
Australia, Austria, Belgium,
Brazil, Bulgaria, Chile,
Croatia, Cyprus, Czech
Republic, Denmark, Egypt,
Estonia, Finland, France,
Germany, Greece,
Honduras, Hungary, Iceland,
Ireland, Israel, Italy, Japan,
Kuwait, Latvia, Lithuania,
Luxembourg, Mozambique,
Netherlands, New Zealand,
North Macedonia, Norway,
Oman, Poland, Portugal,
Romania, Saudi Arabia,
Serbia, Slovakia, Slovenia,
South Afrika, South Korea,
Spain, Sweden, Taiwan,
Turkey, United Kingdom,
Uruguay
National bans of asbestos are reported in these countries (Lin et al„ 2019;
I ARC. 2012a).
6154 B.4 Assessment History
6155
6156 Table Apx B-4. Assessment History of Asbestos
Authoring Organization
Publication
EPA assessments
EPA, Integrated Risk Information System (IRIS)
IRIS Assessment on Asbestos (U.S. EPA, 1988b)
EPA, IRIS
IRIS Assessment on Libby Amphibole Asbestos
(U.S. EPA. 2014c)
EPA, Region 8
Site-Wide Baseline Ecological Risk Assessment,
Libby Asbestos Superfund Site, Libby Montana
(U.S. EPA. 2014b)
EPA, Drinking Water Criteria Document
Drinking Water Criteria Document for Asbestos
(U.S. EPA. 1985)
EPA, Ambient Water Quality Criteria for Asbestos
Asbestos: Ambient Water Quality Criteria (U.S.
EPA. 1980)
EPA, Final Rule (40 CFR part 763)
Asbestos; Manufacture, Importation, Processing and
Distribution in Commerce Prohibitions (1989)
EPA, Asbestos Modeling Study
Final Report; Asbestos Modeling Studv (Versar,
1988)
EPA, Asbestos Exposure Assessment
Revised Report to support ABPO rule (ICFI, 1988)
EPA, Nonoccupational Exposure Report
Revised Draft Report, Nonoccupational Asbestos
Exposure (Versar, 1987)
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Authoring Organization
Publication
EPA, Airborne Asbestos Health Assessment Update
Support document for NESHAP review (U.S. EPA,
1986a)
Other U.S.-based organizations
National Institute for Occupational Safety and Health
(NIOSH)
Asbestos Fibers and Other Elongate Mineral
Particles: State of the Science and Roadmap for
Research (NIOSH. 2011a)
Agency for Toxic Substances and Disease Registry
(ATSDR)
Toxicoloeical Profile for Asbestos (ATSDR, 2001)
National Toxicology Program (NTP)
Report on Carcinogens, Fourteenth Edition (NIH,
2016)
CA Office of Environmental Health Hazard
Assessment (OEHHA), Pesticide and Environmental
Toxicology Section
Public Health Goal for Asbestos in Drinking Water
(CalEPA. 2003)
International
International Agency for Research on Cancer (IARC)
IARC Monographs on the Evaluation of
Carcinogenic Risks to Humans. Arsenic, Metals,
Fibres, and Dusts. Asbestos (Chrysotile, Amosite,
Crocidolite, Tremolite, Actinolite, and
Anthophyllite) (IARC, 2012c)
World Health Organization (WHO)
World Health Organization (WHO) Chrysotile
Asbestos (WHO. 2014)
Environment and Climate Change Canada
Prohibition of Asbestos and Products Containing
Asbestos Regulations (EC/HC, 2019)
6157
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Appendix C LIST OF SUPPLEMENTAL DOCUMENTS
Appendix C incudes a list and citations for all supplemental documents included in the Part 2 of the
Draft Risk Evaluation for Asbestos. See Docket EPA-HQ-QPPT-2019-0501 for all publicly released
files associated with this draft risk evaluation package.
Associated Systematic Review Data Quality Evaluation and Data Extraction Documents - Provides
additional detail and information on individual study evaluations and data extractions including criteria
and data quality results.
Systematic Review Protocol (U.S. EPA. 2023n) - In lieu of an update to the Draft Systematic Review
Protocol Supporting TSCA Risk Evaluations for Chemical Substances, also referred to as the "2021
Draft Systematic Review Protocol" (U.S. EPA. 20211 this systematic review protocol for the Draft
Risk Evaluation for Asbestos Part 2 describes some clarifications and different approaches that were
implemented than those described in the 2021 Draft Systematic Review Protocol in response to (1)
SACC comments, (2) public comments, or (3) to reflect chemical-specific risk evaluation needs.
This supplemental file may also be referred to as the "Asbestos Part 2 Systematic Review Protocol."
[Supplemental File 2]
Systematic Review Supplemental File: Data Quality Evaluation and Data Extraction Information for
Physical and Chemical Properties (U.S. EPA. 2023f) - Provides a compilation of tables for the data
extraction and data quality evaluation information for Asbestos Part 2. Each table shows the data
point, set, or information element that was extracted and evaluated from a data source that has
information relevant for the evaluation of physical and chemical properties. This supplemental file
may also be referred to as the "Asbestos Part 2 Data Quality Evaluation and Data Extraction
Information for Physical and Chemical Properties." [Supplemental File 3J
Systematic Review Supplemental File: Data Quality Evaluation and Data Extraction Information for
Environmental Fate and Transport (U.S. EPA. 2023 d) - Provides a compilation of tables for the
data extraction and data quality evaluation information for Asbestos Part 2. Each table shows the
data point, set, or information element that was extracted and evaluated from a data source that has
information relevant for the evaluation for Environmental Fate and Transport. This supplemental file
may also be referred to as the "Asbestos Part 2 Data Quality Evaluation and Data Extraction
Information for Environmental Fate and Transport." [Supplemental File 4]
Systematic Review Supplemental File: Data Quality Evaluation and Data Extraction Information for
Environmental Release and Occupational Exposure (U.S. EPA. 2023 e) - Provides a compilation of
tables for the data extraction and data quality evaluation information for Asbestos Part 2. Each table
shows the data point, set, or information element that was extracted and evaluated from a data source
that has information relevant for the evaluation of environmental release and occupational exposure.
This supplemental file may also be referred to as the "Asbestos Part 2 Data Quality Evaluation and
Data Extraction Information for Environmental Release and Occupational Exposure." [Supplemental
File 5]
Systematic Review Supplemental File: Data Quality Evaluation Information for General Population,
Consumer, and Environmental Exposure (U.S. EPA. 2023h) - Provides a compilation of tables for
the data quality evaluation information for Asbestos Part 2. Each table shows the data point, set, or
information element that was evaluated from a data source that has information relevant for the
evaluation of general population, consumer, and environmental exposure. This supplemental file
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may also be referred to as the "Asbestos Part 2 Data Quality Evaluation Information for General
Population, Consumer, and Environmental Exposure." [Supplemental File 6]
Systematic Review Supplemental File: Data Extraction Information for General Population,
Consumer, and Environmental Exposure (U.S. EPA. 2023 c) - Provides a compilation of tables for
the data extraction for Asbestos Part 2. Each table shows the data point, set, or information element
that was extracted from a data source that has information relevant for the evaluation of general
population, consumer, and environmental exposure. This supplemental file may also be referred to as
the "Asbestos Part 2 Data Extraction Information for General Population, Consumer, and
Environmental Exposure." [Supplemental File 7]
Systematic Review Supplemental File: Data Quality Evaluation Information for Raman Health
Hazard Epidemiology (U.S. EPA. 20230 - Provides a compilation of tables for the data quality
evaluation information for Asbestos Part 2. Each table shows the data point, set, or information
element that was evaluated from a data source that has information relevant for the evaluation of
epidemiological information. This supplemental file may also be referred to as the "Asbestos Part 2
Data Quality Evaluation Information for Human Health Hazard Epidemiology." [SupplementalFile
8]
Systematic Review Supplemental File: Data Quality Evaluation Information for Environmental
Hazard (U.S. EPA. 2023g) - Provides a compilation of tables for the data quality evaluation
information for Asbestos Part 2. Each table shows the data point, set, or information element that
was evaluated from a data source that has information relevant for the evaluation of environmental
hazard toxicity information. This supplemental file may also be referred to as the "Asbestos Part 2
Data Quality Evaluation Information for Environmental Hazard." [Supplemental File 9]
Systematic Review Supplemental File: Data Extraction Information for Environmental Hazard and
Human Health Hazard Animal Toxicology and Epidemiology (U.S. EPA. 2023b) - Provides a
compilation of tables for the data extraction for Asbestos Part 2. Each table shows the data point, set,
or information element that was extracted from a data source that has information relevant for the
evaluation of environmental hazard and human health hazard animal toxicology and epidemiology
information. This supplemental file may also be referred to as the "Asbestos Part 2 Data Extraction
Information for Environmental Hazard and Human Health Hazard Animal Toxicology and
Epidemiology." [SupplementalFile 10]
Associated Supplemental Information Documents - Provides additional details and information on
exposure, hazard and risk assessments.
Risk Calculator for Take Home - April 2024. Spreadsheet provides details and information on the
take-home exposure assessment and analyses including modeling inputs and outputs. [Supplemental
File 11]
Ambient Air Specific Facilities Released Concentrations - April 2024. Spreadsheet provides details
and information on the approaches to combined AERMOD TRI and NEI ambient air concentrations
for specific facilities [Supplemental File 12].
Ambient Air Generic Facilities andDepo Concentrations - Fall 2023. Spreadsheet provides details
and information on the approaches to combined AERMOD TRI and NEI ambient air concentrations
for generic facilities [Supplemental File 13].
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Risk for Calculator Consumer - April 2024 [Supplemental File 14]
Risk for Calculator General Population - April 2024 [Supplemental File 15]
Aggregate Analysis - April 2024 [Supplemental File 16]
Environmental Release and Occupational Exposure Data Tables - April 2024 [Supplemental File
17]
Risk Calculator for Occupational Exposure - April 2024 [Supplemental File 18]
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Appendix D PHYSICAL AND CHEMICAL PROPERTIES AND
FATE AND TRANSPORT DETAILS
D.l Physical and Chemical Properties Evidence Integration
EPA gathered and evaluated physical and chemical property data and information according to the
process described in the Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for
Chemical Substances (U.S. EPA. 2021). During this evaluation of Asbestos, EPA considered both
measured and estimated property data/information set forth in Table 2-1. Most values were taken from
the Final Scope of the Risk Evaluation for Asbestos Part 2: Supplemental Evaluation Including Legacy
Uses and Associated Disposals of Asbestos (U.S. EPA. 2022b) except for the surface area (anthophyllite
and tremolite), individual fiber diameter (anthophyllite), particle dimensions (crocidolite, amosite,
actinolite, and LAA), density (anthophyllite, tremolite, and actinolite), refractive index (actinolite),
tensile strength (crocidolite, amosite and tremolite), and zeta potential (anthophyllite and tremolite).
Essential Composition
EPA extracted and evaluated twelve sources containing asbestos fibers essential composition. Six of the
sources were identified and evaluated as high-quality data sources and the remaining six as medium-
quality data sources. EPA selected four of the high-quality essential composition data sources for the
risk evaluation of asbestos part 2. The essential composition provides a description of the chemical
compounds and/or elements for the identification of different asbestos fiber types. As described in Table
2-1, the general essential composition of asbestos fibers consists of hydrated silicates with a layer of
brucite, Na, Fe, Mg, and/or Ca (NLM. 2021; Larranaga et al.. 2016; U.S. EPA. 2014c; Badollet. 1951).
Color and Luster
EPA evaluated and extracted twenty sources containing information on the color of asbestos fibers and
thirteen data sources containing asbestos fibers luster information. The luster provides a general
description of asbestos fibers' overall surface sheen or brightness. From the color data sources, sixteen
were extracted and evaluated as high-quality sources and four as medium-quality sources. All the luster
data sources were evaluated and extracted as high-quality sources. EPA selected four high-quality
sources describing the color and luster of chrysotile, crocidolite, amosite, anthophyllite, tremolite, and
actinolite, as illustrated in Table 2-1 (NLM. 2021; Zhong et al.. 2019; Larranaga et al.. 2016; Badollet.
1951). No color and luster data were identified in the systematic review process for Libby Amphibole
Asbestos.
Surface Area
EPA evaluated and extracted fourteen sources containing surface area information of asbestos fibers.
Nine of the data sources were determined to be of high-quality and five were of medium-quality. EPA
selected two high-quality sources and one medium-quality data source to represent the range of the
identified surface areas at ambient temperature for chrysotile, crocidolite, amosite, anthophyllite,
tremolite, and Libby Amphibole as illustrated in Table 2-1 (Pollastri et al.. 2014; U.S. EPA. 2014c;
Addison et al.. 1966). No surface area data were identified in the systematic review process for
actinolite.
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6325
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6327
6328
6329
6330
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6332
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6334
6335
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Fiber Diameter
EPA evaluated and extracted fifteen sources containing asbestos fiber diameters. From these data
sources, 11 were high-quality and 4 were medium quality. The fiber diameter describes the cross-
sectional distance across the individual asbestos fiber types. Gaze (1965) and Le Bouffant (1980)
reported amosite fiber diameters ranging from greater or equal to 0.1 to 1.2 |im. Le Bouffant (1980) also
reported differing anthophyllite fiber diameters (>0.1 to 1.4 |im). Gaze (1965). Le Bouffant (1980). and
NLM (2021) reported chrysotile fiber diameters ranging from greater or equal to 0.1 to 0.8 |im. Gaze
(1965). Le Bouffant (1980). and Hwang (1983) reported crocidolite fiber diameters ranging from 0.08 to
1.0 microns. U.S. EPA (2014c) reported Libby amphibole fiber diameter of 0.61 |im. For the purpose of
this draft risk evaluation, EPA selected two high-quality sources and one medium-quality data source
describing the fiber diameters of chrysotile, crocidolite, amosite, anthophyllite, tremolite, and Libby
Amphibole, as illustrated in Table 2-1 (NLM. 2021; U.S. EPA. 2014c; Hwang. 1983; Le Bouffant.
1980). No fiber diameter data were identified in the systematic review process for actinolite.
Fiber Dimensions
EPA evaluated and extracted 24 sources containing data on asbestos fiber dimensions. From these data
sources, 19 were evaluated as high- and 5 as medium-quality. The fiber dimensions describe the typical
length and diameter of the individual asbestos fiber types. EPA selected the fiber dimension information
from five high-quality sources to represent the range of the identified fiber dimensions. These sources
reported fiber lengths ranging 0.8 to 36 |im and widths from 0.02 to 12 |im for chrysotile, crocidolite,
amosite, actinolite, and Libby amphibole, as described in Table 2-1 (Lowers and Bern. 2009; Snyder et
al.. 1987; Thorne et al.. 1985; Virta et al.. 1983; Siegrist and Wvlie. 1980). No fiber dimension data
were identified in the systematic review process for anthophyllite and tremolite.
Hardness
EPA evaluated and extracted 12 sources containing hardness data for asbestos fibers. From these data
sources, six were evaluated as high-quality and six as medium quality. The hardness describes the
asbestos fibers' resistance to deformation when an external force is applied. EPA four high-quality
sources to represent the range of the identified hardness data for asbestos fibers. These sources reported
fiber hardness ranging from 5.5 to 6 Mohs for actinolite, amosite, and tremolite, and 2.5 to 4 Mohs for
chrysotile and crocidolite, as summarized in Table 2-1 (NLM. 2021; Larranaga et al.. 2016; Virta. 2004;
Badollet. 1951). No fiber hardness data were identified in the systematic review process for Libby
amphiboles.
Density
EPA evaluated and extracted twelve sources containing asbestos fiber density. From these data sources,
13 were evaluated as high-quality and thirteen as medium quality. EPA selected four high-quality
sources to represent the range of the identified asbestos fiber density data. These sources reported fiber
densities ranging 2.19 to 3.3 for chrysotile, crocidolite, amosite, anthophyllite, tremolite, and actinolite
as described in Table 2-1 (Elsevier. 2021a. b, c; Virta. 2004). No density data were identified in the
systematic review process for Libby amphiboles.
Refractive Index
EPA evaluated and extracted 12 sources containing asbestos refractive index information. From these
data sources, nine were evaluated as high-quality and three as medium quality. Refractive index refers to
the ability of a substance to bend light and can be used to identify asbestos fiber types. EPA selected two
high-quality sources to represent the range of the identified asbestos refractive index data. These sources
reported refractive index ranging from 1.53 to 1.701 for chrysotile, crocidolite, amosite, anthophyllite,
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6372
6373
6374
6375
6376
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6382
6383
6384
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tremolite, and actinolite as described in Table 2-1 (NLM. 2021; Lott 1989). No refractive index data
were identified in the systematic review process for Libby amphiboles.
Flexibility and Spinnability
The flexibility and spinnability describes the ability of asbestos fibers to be bent, stretched, spun, and
twisted without being deformed. EPA evaluated and extracted two high-quality data sources containing
asbestos flexibility and spinnability data. These sources reported good to high flexibility for chrysotile,
crocidolite, and amosite, but poor flexibility for anthophyllite, tremolite, and actinolite. Likewise, fair to
good spinnability was reported for chrysotile, crocidolite, and amosite, with poor spinnability for
anthophyllite, tremolite, and actinolite, as described in Table 2-1 (NLM. 2021; Badollet 1951). No
flexibility and spinnability data were identified in the systematic review process for Libby amphiboles.
Zeta Potential
The zeta potential is a physical property that describes the colloidal stability of suspended fiber types
based on their net surface charge. EPA evaluated and extracted eight data sources containing asbestos
zeta potential data. From these data sources, six were evaluated as high quality and two as medium
quality. These sources reported zeta potentials ranging from 13.6 to 54 mV for chrysotile, anthophyllite,
and tremolite and -20 to -40 mV for crocidolite and amosite as described in Table 2-1 (Virta. 2004;
Schiller and Payne. 1980). No zeta potential data were identified in the systematic review process for
actinolite and Libby amphiboles.
Decomposition Temperature
The decomposition temperature describes the temperature at which asbestos fiber types are decomposed
and recrystallized into non-asbestiform fiber types. EPA evaluated and extracted 23 data sources
containing asbestos decomposition temperature data. From these data sources, 19 were evaluated as high
quality and four as medium quality. EPA selected three sources to represent the range of the identified
asbestos decomposition temperatures. Identified decomposition temperatures ranged from 400 to 900 °C
for chrysotile, crocidolite, and amosite and 950 to 1,296 °C for anthophyllite, tremolite, and actinolite as
described in Table 2-1 (Elsevier. 2021a. b; Virta. 2004). No decomposition temperature data were
identified in the systematic review process for Libby amphiboles.
D.2 Fate and Transport
D.2.1 Approach and Methodology
EPA conducted a Tier I assessment to identify the environmental compartments (i.e., water, sediment,
biosolids, soil, groundwater, air) of major and minor relevance to the fate and transport of asbestos. EPA
then conducted a Tier II assessment to identify the fate pathways and media most likely to cause
exposure from environmental releases. Media-specific fate analyses were performed as described in
Sections D.2.2, D.2.3, and D.2.4. Fate and transport approaches typically used for discrete organic
chemicals, such as the use of EPI Suite™ models or the LRTP screening tool were not used, as they are
not applicable for asbestos fibers. However, EPA used AERMOD to estimate air deposition of asbestos
fibers as described in Section 3.3.4.
D.2.2 Air and Atmosphere
EPA obtained limited information about the air transport of asbestos fibers during the systematic review
process. Asbestos is a category of persistent mineral fibers that can be found in soils, sediments, and
lofted in air and windblow dust (ATSDR. 2001). Small spherical fibers (<1 (j,m) can remain suspended
in air and water for extended periods of time and be transported over long distances (ATSDR. 2001).
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EPA calculated the potential sphericity of asbestos particles and used AERMOD to estimate air
deposition, as described in Section 3.3.4. Because air suspended asbestos fibers will eventually settle to
soils, water bodies, and sediments, movement therein may occur via erosion, runoff, or mechanical
resuspension (e.g., wind-blown dust, vehicle traffic) (ATSDR. 2001).
D.2.3 Aquatic Environments
D.2.3.1 Surface Water
Asbestos fibers are not expected to undergo abiotic degradation processes such as hydrolysis and
photolysis in aquatic environments under environmentally relevant conditions. Asbestos forms stable
suspensions in water; under acidic conditions (pH = 1-3) surface minerals may leach into solution
(Clark and Holt 1961). with reported rates of dissolution being dependent on the mineral surface area
and temperature conditions. Choi (1972) reported the removal of the brucite layer which resulted in
release of Mg2+ leaving a silica skeleton. Higher release of Mg2+ was reported in smaller asbestos
particles. Under neutral pH conditions, the underlying silicate structure remains unchanged (Schreier
and Lavkulich. 2015; Favero-Longo et al.. 2005; Gronow. 1987; Bales and Morgan. 1985; Choi and
Smith. 1972). Asbestos fibers have been reported to absorb natural organic matter by replacing
positively charged Mg-OH2+ sites and acquiring a negative surface charge, which might increase the
transport and resuspension of asbestos fibers from aquatic soils and sediments (Bales and Morgan.
1985).
The reported half4ife in water is greater than 200 days (NICNAS. 1999). In surface water, the
concentration of suspended asbestos fibers tends to naturally decrease with greater than 99 percent
observed in water reservoirs with hydraulic detention times greater than 1 year (Bales et al.. 1984).
Storm events may increase the deposition and resuspension of asbestos fibers (Schreier and Lavkulich.
2015).
D.2.3.2 Sediments
Asbestos can be transported to sediment from overlying surface water by settling of suspended asbestos
fibers. In surface water suspended asbestos fibers tend to naturally decrease by settling into aquatic
sediments. Greater than 99 percent reduction of fiber concentrations have been documented for water
bodies with hydraulic detention times greater than 1 year (Bales et al.. 1984). In general, asbestos fibers
in surface water will eventually settle into sediments, but environmental stress such as storm events,
may increase the resuspension of asbestos fibers (Schreier and Lavkulich. 2015). Other sources of
asbestos fibers in soils and sediments are biosolids from water treatment systems. The use of coagulation
and flocculation treatment processes have been reported to remove 80 to 99 percent of asbestos fibers in
sludge, with higher removals during the use of filtration treatment units (Kebler et al.. 1989; Lauer and
Convery. 1988; Bales et al.. 1984; McGuire et al.. 1983; Lawrence and Zimmermann. 1977; Schmitt et
al.. 1977; Lawrence and Zimmermann. 1976). Overall, asbestos in water will eventually settle into
sediments and biosolids from wastewater treatment plants.
D.2.4 Terrestrial Environments
Asbestos is released to terrestrial environments via land application of biosolids, disposal of solid waste
to landfills, windblown resuspension, and atmospheric deposition.
D.2.4.1 Soil
In general, asbestos fibers will eventually settle from surface water and the atmosphere to sediments and
soil, and movement therein may occur via erosion, runoff, or mechanical resuspension (wind-blown
dust, vehicle traffic, etc.) (ATSDR. 2001). Asbestos release from soil to air will most likely occur under
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high wind velocities and lower water content conditions (Maulida et al.. 2022). Weathering of asbestos
fibers might result in leaching of Mg and trace metals into the lower soil horizons (Schreier et al.. 1987).
Leaching of asbestos fibers into ground water is unlikely, however the presence of natural organic
matter could increase fiber mobility (Mohantv et al.. 2021).
D.2.4.2 Groundwater
Sources of asbestos in ground water include the occurrence and weathering of asbestos minerals,
mechanical disturbance of contaminated sites, erosion, and runoff. Leachate from landfill sites is
unlikely but has been documented in the presence of natural organic matter (Mohantv et al.. 2021;
Schreier et al.. 1987).
D.2.4.3 Landfills
As stated in the Final Scope of the Risk Evaluation for Asbestos Part 2: Supplemental Evaluation
Including Legacy Uses and Associated Disposals of Asbestos (U.S. EPA. 2022b). most of the total on-
site and off-site disposal or other releases of friable asbestos are released to land (by means of RCRA
Subtitle C landfills and other disposal landfills). Of the total releases, 77 lb were released to air (stack
and fugitive air emissions), and 0 lb were released to water (surface water discharges) (U.S. EPA.
2022b). In general, asbestos fibers (all six types) are not likely to be leached out of a landfill. However,
the presence of natural organic matter could increase fiber mobility (Mohantv et al.. 2021).
D.2.4.4 Biosolids
Sludge is defined as the solid, semi-solid, or liquid residue generated by wastewater treatment processes.
The term "biosolids" refers to treated sludge that meet the EPA pollutant and pathogen requirements for
land application and surface disposal (40 CFR part 503).
In general, asbestos fibers are resistant to biodegradation in water treatment and are expected to settle
into biosolids from wastewater treatment plants, as described in Section D.2.5.2.
D.2.5 Persistence Potential of Asbestos
Persistence, in terms of environmental protection, refers to the length of time a contaminant remains in
the environment. Asbestos is considered a persistent and naturally occurring mineral fiber and are
largely chemically inert in the environment (ATSDR. 2001). Under extreme environmental conditions
asbestos fibers have been reported to undergo morphological changes and loss of trace metals from the
first layer of the silicate structure, but the underlying silicate structure remains unchanged at neutral pH.
In general, asbestos fibers do not react or dissolve in most environmental conditions (Favero-Longo et
al.. 2005; Gronow. 1987; Schreier et al.. 1987; Bales and Morgan. 1985; Choi and Smith. 1972).
D.2.5.1 Destruction and Removal Efficiency
Destruction and removal efficiency (DRE) is a percentage that represents the mass of a pollutant
removed or destroyed in a thermal incinerator relative to the mass that entered the system. EPA requires
that hazardous waste incineration systems destroy and remove at least 99.99 percent of each harmful
chemical in the waste, including treated hazardous waste (46 FR 7684).
EPA extracted and evaluated six high quality data sources containing asbestos incineration and thermal
treatment information. One study reported the incineration of ACM with up to 7.3 percent chrysotile, 2.7
percent amosite, and trace levels of crocidolite in a combustion chamber operating between 850 to 900
°C. After incineration, asbestos fibers were not detected within the solid products or exhaust gas (Osada
et al.. 2013). A second study evaluated the fate of chrysotile asbestos between 100 to 1,000 °C, resulting
on morphological changes rendering non asbestos fibers between 810 to 1,000 °C and loss of water
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between 100 to 600 °C (Jolicoeur and Duchesne. 1981). Other thermal treatment approaches have
reported to complete loss of asbestos with thermochemical treatment and partial loss of asbestos with
microwave thermal treatment of ACMs (Obminski. 2021; Porcu et al.. 2005).
D.2.5.2 Removal in Wastewater Treatment
Wastewater treatment is performed to remove contaminants from wastewater using physical, biological,
and chemical processes. Generally, municipal wastewater treatment facilities apply primary and
secondary treatments. During the primary treatment, screens, grit chambers, and settling tanks are used
to remove solids from wastewater. After undergoing primary treatment, the wastewater undergoes a
secondary treatment. Secondary treatment processes can remove up to 90 percent of the organic matter
in wastewater using biological treatment processes such as trickling filters or activated sludge.
Sometimes an additional stage of treatment such as tertiary treatment is utilized to further clean water
for additional protection using advanced treatment techniques (e.g., ozonation, chlorination,
disinfection). A negative removal efficiency can be reported if the pollutant concentration is higher in
the effluents than the pollutant concentration in the influents.
In general, asbestos fibers are resistant to biodegradation in water treatment and are expected to settle
into biosolids from drinking water and wastewater treatment plants. EPA selected four medium quality
and two high quality sources reporting the removal of asbestos fibers from drinking water treatment
processes. The reported removal of asbestos fibers ranged 80 to 99 percent for systems employing
coagulation, flocculation treatment processes, and filtration treatment units (Kebler et al.. 1989; Bales et
al.. 1984; McGuire et al.. 1983; Lawrence and Zimmermann. 1977; Schmitt et al.. 1977; Lawrence and
Zimmermann. 1976). In addition, the EPA selected one high quality data source reporting concentrations
of asbestos fibers below detection limits in the effluent of a wastewater treatment plant receiving raw
wastewater with 12.2 M fibers/L (Lauer and Convery. 1988). Overall, asbestos fibers are expected to
settle into biosolids from wastewater treatment plants and eventually disposed in land application of
biosolids and/or landfills.
D.2.6 Bioaccumulation Potential of Asbestos
Bioaccumulation is the absorption of chemical from both its environment and its diet. Bioconcentration
in aquatic organisms occurs when a substance is absorbed by an organism from its environment only
through respiratory and external uptake and does not include food ingestion. For some chemicals
(particularly those that are persistent and hydrophobic), the magnitude of bioaccumulation can be
substantially greater than the magnitude of bioconcentration (U.S. EPA. 2003b).
EPA evaluated and extracted five high-quality data sources containing asbestos body burden and
bioconcentration information on fish and clams. Three of the studies reported asbestos body burden and
bioconcentration information for clams. The asbestos body burden for clams was reported to be 132.1 to
147.3 fibers/mg dry weight gill tissue and 903.7 to 1,127.4 fibers/mg dry weight visceral tissue after a
30-day exposure to 108 fibers/L chrysotile asbestos (Belanger et al.. 1986a. b). A clam 30-day asbestos
exposure to 108 fibers/L asbestos fibers resulted in BCF values of 0.308 in gill tissue, 1.89 in viscera
tissue, and 1.91 in whole clam homogenates (Belanger et al.. 1987). One study evaluated the body
burden in Japanese Medaka after a 28-day exposure to chrysotile asbestos at 1010 fibers/L
concentrations, fish total body burden was 375.7 fibers/mg (Belanger et al.. 1990). In addition, Sunfish
exposure to 106 fibers/L chrysotile asbestos resulted in lost scales and epidermal tissue erosion
(Belanger et al.. 1986c). Based on the reported low BCF values for asbestos, asbestos fibers are not
expected to bioaccumulate (ATSDR. 2001).
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Appendix E ENVIRONMENTAL RELEASES AND
OCCUPATIONAL EXPOSURE ASSESSMENT
E.l Components of an Occupational Exposure and Release Assessment
EPA describes the assessed COUs for asbestos in Section 1.1.2; however, some COUs differ from the
specific asbestos processes and associated exposure/release scenarios. Therefore, Table 3-1 provides a
crosswalk that maps the asbestos COUs to the more specific OESs. The environmental release and
occupational exposure assessments of each OES comprised the following components:
• Process Description: A description of the OES, which includes the chemical function, products
containing asbestos, process equipment, batch parameters, and process flow diagram.
• Facility Estimates: A characterization of the potential number of employment establishments
and work sites where asbestos or asbestos-containing products are present for an OES. Workers
and ONUs from one establishment may operate at several sites annually for some COUs,
whereas employees within other COUs may operate at only one site or establishment
permanently.
• Environmental Release Assessment
o Environmental Release Sources: A description of the potential sources of
environmental releases in the process and their expected media of release for the OES.
o Environmental Release Assessment Results: Estimates of asbestos released into each
environmental media (surface water, POTW, non POTW-WWT, fugitive air, stack air,
and each type of land disposal) for the given OES.
• Occupational Exposure Assessment
o Worker Activities: A description of the worker activities, including an assessment of
potential points of worker and ONU exposure,
o Number of Workers and Occupational Non-users: An estimate of the number of
workers and occupational non-users potentially exposed to the chemical for the given
OES.
o Occupational Inhalation Exposure Results: Central tendency and high-end estimates
of inhalation exposure to workers and ONUs.
E.2 Approach and Methodology for Process Descriptions
EPA performed a literature search to find descriptions of processes involved in each OES. EPA used a
systematic review approach as discussed in Section 1.2 to complete the literature search. Where
chemical-specific process descriptions were unclear or not reasonably available, EPA referenced
relevant Emission Scenario Documents (ESDs) or Generic Scenarios (GSs). EPA developed the process
descriptions to include facility throughputs or hypothetical scenarios assessed, key process steps, and
where asbestos is present (e.g., physical state, concentration) throughout the process. Appendices E.10
through E.16 provide process descriptions for each OES.
E.3 Approach and Methodology for Number of Sites and Establishments
CDR data were not available for the COUs included in this occupational exposure assessment.
Therefore, EPA used data from the Bureau of Labor Statistics (BLS) and the U.S. Census' Statistics of
U.S. Businesses (SUSB), NFPA data, and literature search data to estimate the number of establishments
and worksites for each OES.
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For all OESs, except the Handling asbestos-containing building materials during firefighting or other
disaster response activities, EPA used BLS and SUSB data to estimate the number of employment
establishments as follows:
1. Identify the North American Industry Classification System (NAICS) codes for the industry
sectors associated with the OES.
2. Estimate total number of establishments using SUSB data on total establishments by 6-digit
NAICS.
3. Use market penetration data to estimate the percentage of establishments likely to be using
asbestos or asbestos-containing products.
4. Combine the data generated in Steps 1 through 3 above to produce an estimate of the number of
establishments using asbestos in each 6-digit NAICS code and sum across all applicable NAICS
codes for the OES to arrive at a total estimate of the number of establishments within the OES.
5. If market penetration data required for Step 3 are not available, use generic industry data from
GSs, ESDs, and other literature sources on typical throughputs/use rates, operating schedules,
and the asbestos volume used within the OES to estimate the number of establishments.
For the Handling asbestos-containing building materials during firefighting or Other disaster response
activities OES, the number of establishments (i.e., fire departments) were determined from NFPA data
rather than BLS and SUSB data due to data limitations within BLS and SUSB for firefighting and
disaster response occupations.
To estimate the number of work sites, EPA assumed that employees work at the establishment of
employment only and workers do not operate at sites outside of the establishment of employment for the
following three OES: Use, repair, or removal of industrial and commercial appliances or machinery
containing asbestos; Handling articles or formulations that contain asbestos; and Waste handling,
disposal, and treatment. Therefore, the number of establishments is equal to the number of sites for these
three OESs.
However, for the Handling asbestos-containing building materials during maintenance, renovation, and
demolition activities as well as the Handling asbestos-containing building materials during firefighting
or other disaster response activities OES, the number of establishments is not equal to the number sites
since workers employed in one establishment may perform work activities at various sites annually. For
these two OESs, EPA used literature search data to estimate the number of sites. See Appendix E.10.2
and Appendix E.l 1.2 for more information on these calculations.
A summary of the number of establishments and sites that EPA determined for each OES is shown in
Table Apx E-l. The number of establishments and sites may be different for each type of release within
the same OES if sufficient data were available to make this differentiation.
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6617 TableApx E-l. Summary of EPA's Estimates for the Number of Establishments and Sites for
6618 EachOES
OES
Number of
Establishments
Number of
Sites
Notes
Handling asbestos-
containing building
materials during
maintenance, renovation,
and demolition activities
683,066
46,789
The number of employment establishments is
based on U.S. Census Bureau data (see
Table_Apx E-20, whereas number of
release/exposure sites is based on literature values
for total demolition waste generated, percentage
of residential vs commercial waste, area per
building, waste generated per area of building,
and percentage of buildings with friable asbestos
(Tiseo. 2022; EIA. 2018; U.S. EPA. 2003a.
1988a).
Handling asbestos-
containing building
materials during
firefighting or other
disaster response
activities
29,452
97,920
The number of employment establishments is
based on NFPA reported data for the number of
fire departments (NFPA. 2022b). whereas number
of release/exposure sites is based on NFPA report
of fires per year, and percentage of buildings with
friable asbestos (NFPA. 2022a; U.S. EPA. 1988a).
Use, repair, or removal of
industrial and
commercial appliances or
machinery containing
asbestos
29,211
29,211
The bounding estimate is based on U.S. Census
Bureau data for NAICS codes 324110 (Petroleum
Refineries), 325199 (All Other Basic Organic
Chemical Manufacturing), and 423830 (Industrial
Machinery and Equipment Merchant
Wholesalers).
Handling articles or
formulations that contain
asbestos
15,592
15,592
The bounding estimate is based on U.S. Census
Bureau data for NAICS codes 336411 (Aircraft
Manufacturing), 541715 (Research and
Development in the Physical, Engineering, and
Life Sciences (except Nanotechnology and
Biotechnology)), and 611310 (Colleges,
Universities, and Professional Schools).
Waste handling, disposal,
and treatment
4,972
4,972
The bounding estimate is based on U.S. Census
Bureau data for NAICS codes 221117 (Biomass
Electric Power Generation), 562211 (Hazardous
Waste Treatment and Disposal), 562212 (Solid
Waste Landfill), 562920 (Materials Recovery
Facilities), and 562998 (All Other Miscellaneous
Waste Management Services).
6619 E.4 Environmental Releases Approach and Methodology
6620 Releases to the environment are a component of potential exposure and may be derived from reported
6621 data that are obtained through direct measurement via monitoring, calculations based on empirical data,
6622 and/or assumptions and models. For each OES, EPA attempted to provide annual releases, high-end, and
6623 central tendency daily releases, as well as the number of release days per year for each media of release
6624 (air, water, and land).
6625
6626 EPA used the following hierarchy in selecting data and approaches for assessing environmental releases:
6627 1. Monitoring and measured data:
6628 a. Releases calculated from site-specific concentration in medium and flow rate data
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b. Releases calculated from mass balances or emission factor methods using site-specific
measured data
EPA's preference was to rely on site-specific release data reported in TRI, DMR, and NEI, where
available. Where releases are expected for an OES—but TRI, DMR, and NEI data were not available or
where EPA determined TRI, DMR, and/or NEI data did not capture the entirety of environmental
releases for an OES—releases were estimated using data from the National Response Center (NRC).
EPA's general approach to estimating releases from these sources is described in Appendix E.4.1
through Appendix E.4.3. Specific details related to the use of release data or models for each OES can
be found in Appendix E.10 through Appendix E.16.
EPA used deterministic calculations to estimate the final release result. EPA used combinations of point
estimates of each input parameter to estimate a central tendency and high-end for each final release
result. EPA documented the method and rationale for selecting parametric combinations to be
representative of central tendency and high-end in the relevant OES subsections in Appendix E.10
through Appendix E. 16.
E.4.1 Approach for Estimating Wastewater Discharges
This section describes EPA's methodology for estimating daily wastewater discharges from industrial
and commercial sites containing asbestos. No wastewater discharges of asbestos were reported in the
2016 to 2020 TRI. Therefore, EPA used 2015 to 2022 NRC data fNRC. 2022) to estimate daily
wastewater discharges for the OES where available. Section 103 of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) requires the person in charge of a vessel or an
onshore or offshore facility immediately notify the NRC when a CERCLA hazardous substance is
released at or above the reportable quantity in any 24-hour period, unless the release is federally
permitted. The NRC is an emergency call center maintained and operated by the U.S. Coast Guard that
fields initial reports for pollution and railroad incidents. Information reported to the NRC is available on
the NRC website. For OES without NRC data, EPA used alternate assessment approaches to estimate
wastewater discharges. Both approaches, that for OES with NRC data and that for OES without these
data, are described below.
E.4.1.1 Approach for Estimating Wastewater Discharges from NRC
EPA identified 2012 to 2022 NRC data for incidents within the Handling asbestos-containing building
materials during maintenance, renovation, and demolition activities OES.
The first step in estimating annual releases was to obtain the NRC data. EPA downloaded annual data
sets from the past 10 years (2012-2022) from the NRC website. EPA then identified all of the data for
spill reports pertaining to asbestos that reached a body of water and excluded reports of asbestos spills
that were contained and did not reach water. This resulted in four reports of asbestos spills that reached
water. EPA mapped each of the data points to an OES using the "Description of Incident" field from the
NRC database to determine how the asbestos was being used prior to the spill.
The final step was to prepare a summary of the wastewater discharges. EPA estimated annual
wastewater discharges by calculating the median and maximum of the reported NRC data. Then, EPA
estimated daily wastewater discharges by dividing the annual releases by the number of operating days
determined for the OES.
To accompany the summary table for each OES, EPA also provided any reasonably available
information on the release duration and pattern, which are needed for the exposure modeling. Release
duration is the expected time per day during which the wastewater discharge may occur. Release pattern
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is the temporal variation of the wastewater discharge, such as over consecutive days throughout the year,
over cycles that occur intermittently throughout the year, or in an instantaneous discharge that occurs
over a short duration. The NRC data set does not include release pattern or duration; therefore, EPA
used information from models or literature, where available.
E.4.1.2 Approach for Estimating Wastewater Discharges from TRI
EPA used TRI data to estimate annual wastewater discharges, average daily wastewater discharges, and
high-end daily wastewater discharges for the following OES:
• Use, Repair, or Removal of Industrial and Commercial Appliances or Machinery Containing
Asbestos
• Handling Articles or Formulations that Contain Asbestos
• Waste Handling, Disposal, and Treatment
Since there were no reported wastewater discharges in the 2016 to 2020 TRI data associated with the
three OES above, EPA does not expect wastewater discharges for these OES. There may be incidental
discharges of asbestos for these OES, however EPA expects those releases to be low and occur
infrequently.
E.4.2 Approach for Estimating Air Emissions
This section describes EPA's methodology for estimating daily air emissions from industrial and
commercial sites containing asbestos. EPA used 2016 - 2020 TRI data (U.S. EPA. 2022a) and 2014 to
2017 NEI data (U.S. EPA. 2022d) to estimate daily air emissions for the OES where available; however,
EPA did not have these data for every OES. For OES without TRI or NEI data, EPA used alternate
assessment approaches to estimate air emissions. Both approaches, that for OES with TRI and NEI data
and that for OES without these data, are described below.
E.4.2.1 Assessment Using TRI and NEI
Where available, EPA used TRI and NEI data to estimate annual and average daily fugitive and stack air
emissions. For air emissions, EPA attempted to estimate both release patterns (i.e., days per year of
release) and release durations (i.e., hours per day the release occurs).
Annual Emissions
Facility4evel annual emissions are available for TRI reporters and major sources in NEI. EPA used the
reported annual emissions directly as reported in TRI and NEI for major sources. NEI also includes
annual emissions for area sources that are aggregated at the county-level. However, for this analysis
only point-source data were available in NEI.
Average Daily Emissions
To estimate average daily emissions for TRI reporters and major sources in NEI, EPA used the
following steps:
1. Obtain total annual fugitive and stack emissions for each TRI reporter and major sources in NEI.
2. Divide the annual stack and fugitive emissions over the number of estimated operating days
(note: NEI data includes operating schedules for many facilities that can be used to estimate
facility-specific days per year).
3. Estimate a release duration using facility-specific data available in NEI, models, and/or literature
sources. If no data is available, list as "unknown."
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E.4.3 Approach for Estimating Land Disposals
This section describes EPA's methodology for estimating daily land disposals from industrial and
commercial sites containing asbestos. EPA used 2016 to 2020 TRI data (U.S. EPA. 2022a) to estimate
daily land emissions for the OES where available; however, EPA did not have these data for every OES.
For OES without TRI data, EPA used alternate assessment approaches to estimate land disposals. Both
approaches, for OES with TRI data and that for OES without these data, are described below.
E.4.3.1 Assessment Using TRI
Where available, EPA used TRI data to estimate annual and average daily land disposal volumes. TRI
includes reporting of disposal volumes for a variety of land disposal methods, including underground
injection, RCRA Subtitle C landfills, land treatment, RCRA Subtitle C surface impoundments, other
surface impoundments, and other land forms of disposal. EPA provided estimates for both a total
aggregated land disposal volume and disposal volumes for each disposal method reported in TRI.
Annual Land Disposal
Facility4evel annual disposal volumes are available directly for TRI reporters. EPA used the reported
annual land disposal volumes directly as reported in TRI for each land disposal method. EPA combined
totals from all land disposal methods from each facility to estimate a total annual aggregate disposal
volume to land.
Average Daily Land Disposal
To estimate average daily disposal volumes, EPA used the following steps:
1. Obtain total annual disposal volumes for each land disposal method for each TRI reporter.
2. Divide the annual disposal volumes for each land disposal method over the number of estimated
operating days.
3. Combine totals from all land disposal methods from each facility to estimate a total aggregate
disposal volume to land.
E.4.3.2 Assessment Using Literature Search Data
EPA used literature search data for sites within the Handling asbestos-containing building materials
during maintenance, renovation, and demolition activities OES.
While EPA identified potential demolition sites in TRI data for this OES, EPA does not expect the TRI
reports to include all demolition sites due to TRI reporting requirements/thresholds. Therefore, EPA
supplemented TRI data using data obtained from literature.
Literature data may include directly measured release data or information useful for release modeling.
Therefore, EPA's approach to literature data differs depending on the type of literature data available.
For example, if site-specific release data is available, EPA may use that data directly to estimate releases
for that site. If site-specific data is available for only a subset of the sites within an OES, EPA may also
build a distribution of the available data and estimate releases from sites within the OES using central
tendency and high-end values from the distribution. If site-specific data is not available, but industry- or
chemical-specific emission factors are available, EPA may use those directly to calculate releases for an
OES or incorporate the emission factors into release models to develop a distribution of potential
releases for the OES. Detailed descriptions of how various literature data was incorporated into release
estimates for each OES are described in Appendix E.l 1.
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E.4.4 Approach for Estimating Number of Release Days
As a part of the assessment of industrial and commercial environmental releases, EPA also estimated the
number of release days for each OES. The Agency used literature search data or made assumptions
when estimating release days for each OES. Industry-specific data that is available in the form of trade
publications or other relevant literature are preferrable when determining the number of release days.
When such data exists, these industry-specific estimates should take precedent over other approaches or
assumptions. If industry-specific data does not exist, EPA may assume 250 operating days per year as
the default release schedule of a commercial or industrial facility based on 5 operating days per week, 50
weeks per year, and 2 weeks per year for shutdown activities. A summary along with a brief explanation
is presented in Table Apx E-2.
Table Apx E-2. Summary of Estimates for Release Days Expected for Each OES
OES
Release
Days
Notes
Handling asbestos-containing
building materials during
maintenance, renovation, and
demolition activities
12
EPA found information on release days per structure
demolished in four industry-specific literature publications
(Hoans et al.. 2020; Raahuwanshi. 2017; Coelho and de
Brito. 2011; Dantata et al.. 2005). To estimate release davs.
EPA used the average of the four sources.
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities
1
Per one industry-specific literature publication, the average
extinguish time of a structure fire is 3 hours (Jeon et al..
2012). EPA rounded this figure up to 1 dav/vr.
Use, repair, or removal of industrial
and commercial appliances or
machinery containing asbestos
250
Assumed 5 days per week and 50 weeks per year with 2
weeks per year for shutdown activities.
Handling articles or formulations
that contain asbestos
250
Assumed 5 days per week and 50 weeks per year with 2
weeks per year for shutdown activities.
Waste handling, disposal, and
treatment
250
Assumed 5 days per week and 50 weeks per year with 2
weeks per year for shutdown activities.
E.5 Occupational Exposure Approach and Methodology
EPA provided occupational exposure results representative of central tendency conditions and high-end
conditions. A central tendency is assumed to be representative of occupational exposures in the center of
the exposure distribution for a given condition of use. For risk evaluation, EPA used the 50th percentile
(median), mean (arithmetic or geometric), mode, or midpoint values of a distribution as representative of
the central tendency scenario. The Agency's preference is to provide the 50th percentile of the exposure
distribution. However, if the full distribution is not known, EPA may assume that the mean, mode, or
midpoint of the distribution represents the central tendency depending on the statistics available for the
distribution.
A high-end is assumed to be representative of occupational exposures that occur at probabilities above
the 90th percentile but below the exposure of the individual with the highest exposure (U.S. EPA. 1992).
For purposes of this risk evaluation, EPA has provided high-end results at the 95th percentile. If the 95th
percentile was not reasonably available, EPA used a different percentile greater than or equal to the 90th
percentile but less than or equal to the 99.9th percentile, depending on the statistics available for the
distribution. If the full distribution was not known and the preferred statistics were not reasonably
available, EPA estimated a maximum or bounding estimate in lieu of the high-end.
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For occupational exposures, EPA used measured or estimated air concentrations to calculate exposure
concentration metrics required for risk assessment, such as average daily concentration (ADC), margin
of exposure (MOE), and excess lifetime cancer risk (ELCR). These calculations require additional
parameter inputs, such as years of exposure, exposure duration and frequency, and lifetime years. EPA
estimated exposure concentrations from occupational monitoring data only because available data was
sufficient to characterize exposure for all occupational exposure scenarios. For the final exposure result
metrics, each of the input parameters (e.g., air concentrations, working years, exposure frequency,
lifetime years) may be a point estimate (i.e., a single descriptor or statistic, such as central tendency or
high-end) or a full distribution.
EPA follows the following hierarchy in selecting data and approaches for assessing inhalation
exposures:
• Monitoring data
o Personal and directly applicable
o Area and directly applicable
o Personal and potentially applicable or similar
o Area and potentially applicable or similar
• Modeling approaches
o Surrogate monitoring data
o Fundamental modeling approaches
o Statistical regression modeling approaches
• Occupational exposure limits (OELs)
o Company-specific OELs for site-specific exposure assessments (e.g., there is only one
manufacturer who provided EPA their internal OEL but did not provide monitoring data)
o OSHA PEL
o Voluntary limits (ACGIH Threshold Limit Value [TLV], NIOSH Recommended
Exposure Limit [REL], Occupational Alliance for Risk Science (OARS) workplace
environmental exposure level (WEEL) [formerly by the American Industrial Hygiene
Association [AIHA])
EPA assessed occupational exposure to asbestos for the following two population categories: male or
female workers who are 16 years or older; and female workers of reproductive age (16 years or older to
less than 50 years). Exposure metrics for inhalation exposures include ADCs, MOEs, and ELCRs. ADC
values were used to calculate MOE, which were used to determine chronic non-cancer risk compared to
a benchmark MOE of 300. Measured and calculated 8-hour TWA data were used to calculate ELCR
(along with IUR), which was used for chronic cancer risk compared to a benchmark of 1 x 10 4, The
approach to estimating each exposure metric is described in Appendix E.5.4.
E.5.1 Worker Activities
EPA performed a literature search and reviewed data from systematic review to identify worker
activities that could potentially result in occupational exposures. Where worker activities were unclear
or not reasonably available, EPA performed targeted internet searches. Worker activities for each OES
can be found in Appendix E. 10 through Appendix E. 16.
E.5.2 Number of Workers and Occupational Non-users
Because CDR data were not available for uses of asbestos covered within this risk evaluation, EPA
utilized U.S. economic data to determine the number of workers, occupational non-users (ONUs), and
establishments as follows:
1. Identify the NAICS codes for the industry sectors associated with each COU.
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2. Estimate total employment by industry/occupation combination using BLS Occupational
Employment Statistics (BLS OES) data (U.S. Census Bureau. 2015).
3. Refine the BLS OES estimates where they are not sufficiently granular by using the SUSB
data on total employment by 6-digit NAICS.
4. Combine the data generated in Steps 1 through 3 above to produce an estimate of the number
of employees exposed to asbestos in each industry/occupation combination, and sum these to
arrive at a total estimate of the number of employees with exposure.
For the occupational exposure scenario on firefighting and other disaster response, EPA estimated the
number of workers and ONUs using data from NFPA (NFPA. 2022b). The survey provides an estimate
for the number of career firefighters at 364,300 and volunteer firefighters at 676,900 (see Appendix
E. 11.4.2). See Appendix E. 10 through Appendix E. 16 for more information on the estimation methods
for number of workers and ONUs for each OES.
Table Apx E-3 presents the confidence rating of data that EPA used to estimate number of workers.
Table Apx E-3
. Data Evaluation of Sources Containing Number of Worker Estimates
Source
Data Type
Data Quality
Rating
OES(s)
(U.S.
Bureau,
2015)
Number of
Workers
High
Handling asbestos-containing building materials
during maintenance, renovation, and demolition
activities; Use, repair, or removal of industrial and
commercial appliances or machinery containing
asbestos; Handling articles or formulations that
contain asbestos; Waste handling, disposal, and
treatment
(1S1FPA.
2022b)
Number of
Workers
High
Handling asbestos-containing building materials
during firefighting or other disaster response
activities
E.5.3 Inhalation Exposure Monitoring
To assess inhalation exposure, EPA reviewed reasonably available exposure monitoring data and
mapped data to specific conditions of use. Monitoring data used in the occupational exposure
assessment include data collected by government agencies such as OSHA and NIOSH, and data found in
published literature. Studies were evaluated using the evaluation strategies laid out in the Application of
Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a).
For each exposure scenario and worker job category ("higher exposure-potential worker," "lower
exposure-potential worker," "worker," or "occupational non-user"), where available, EPA provided
results representative of central tendency and high-end exposure levels. For data sets with six or more
data points, central tendency and high-end exposures were estimated using the 50th and 95th percentile
value from the observed data set, respectively. For data sets with three to five data points, the central
tendency and high-end exposures were estimated using the median and maximum values. For data sets
with two data points, the midpoint and the maximum value were presented. Finally, data sets with only
one data point were presented as-is. For data sets including exposure data that were reported as below
the limit of detection (LOD), EPA estimated the exposure concentrations for these data, following
guidance in EPA's Guidelines for Statistical Analysis of Occupational Exposure Data (U.S. EPA.
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1994V5 A data set comprises the combined exposure monitoring data from all studies applicable to that
condition of use.
For short-term exposures, EPA grouped exposures into 30-minute TWA averaging periods in order to
evaluate using existing toxicity values for this time period. For exposure assessments, personal breathing
zone (PBZ) monitoring data were used to determine the TWA exposure concentration, except in some
cases where area monitoring data was used to evaluate inhalation exposure to ONUs. Table Apx E-4
presents the data quality rating of monitoring data that EPA used to assess occupational exposures. EPA
evaluated monitoring data using the evaluation strategies described in the Application of Systematic
Review in TSCA Risk Evaluations (U.S. EPA. 2018a). For more information on inhalation exposure
monitoring data used to assess worker and ONU exposure for each OES, see Appendix E.10 through
Appendix E.16.
Table Apx E-4. Data
Evaluation of Sources Containing Occupational Exposure Monitoring Data
Source
Data Type
Data Quality
Rating
OES(s)
(Amer Tech Lab.
1979a)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Amer Tech Lab.
1979b)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Amer Tech Lab.
1979c)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Boelter et al.. 2016)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Dvnamac. 1984)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Gunter. 1981)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(TOMA. 1979)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Koppers. 1981)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Langc and Thomulka.
2000a)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Lanse and Thomulka.
2002)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Lanse. 2002)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Manville Serv Corp.
1980b)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Manville Serv Corp.
1980a)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Hervin. 1977)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Scarlett et al.. 2010)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Tannahill et al.. 1990)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
5 Using the —if the geometric standard deviation of the data is less than 3.0 and — if the geometric standard deviation is
V2 2
3.0 or greater.
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Source
Data Type
Data Quality
Rating
OES(s)
(Bailev et al.. 1988)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Lanse. 1999)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Price et al.. 1992)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Lundsren et al.. 1991)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Lanse and Thomulka.
2001)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities;
handling articles or formulations that contain asbestos
(Lanse and Thomulka.
2000c)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(van Orden et al.. 1995)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities;
Handling asbestos-containing building materials during
firefighting or other disaster response activities
(Teschke et al.. 1999)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(OSHA. 2020)
PBZ and
Area
Monitoring
High
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities; Use,
repair, or removal of industrial and commercial
appliances or machinery containing asbestos; Handling
articles or formulations that contain asbestos; waste
handling, disposal, and treatment
(Spence and Rocchi.
1996)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Tech Servs Inc. 1979)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Confidential. 1986)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
maintenance, renovation, and demolition activities
(Wallinsford and
Snvder. 2001)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
firefighting or other disaster response activities
(Lewis and Curtis.
1990)
PBZ
Monitoring
Medium
Handling asbestos-containing building materials during
firefighting or other disaster response activities
(Beaucham and
Eisenbers. 2019)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
firefighting or other disaster response activities
(Brevsse et al.. 2005)
PBZ
Monitoring
High
Handling asbestos-containing building materials during
firefighting or other disaster response activities
(Blake et al.. 2011)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
(Celv-Garcia et al..
2015)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
(Madl et al.. 2014)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
(Mlvnarek and Van
Orden. 2012)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
(NIOSH. 1983)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
(Ahrenholz. 1988)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
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Source
Data Type
Data Quality
Rating
OES(s)
(Confidential. 1986)
PBZ
Monitoring
High
Use, repair, or removal of industrial and commercial
appliances or machinery containing asbestos
(Brorbv et al.. 2013)
PBZ
Monitoring
High
Handling articles or formulations that contain asbestos
(Garcia et al.. 2018)
PBZ
Monitoring
High
Handling articles or formulations that contain asbestos
(Lanse et al.. 2006)
PBZ
Monitoring
Medium
Handling articles or formulations that contain asbestos
(Costello. 1984)
PBZ
Monitoring
Medium
Waste handling, disposal, and treatment
(Lamontaane et al..
2001)
PBZ
Monitoring
High
Waste handling, disposal, and treatment
(Anania et al.. 1978)
PBZ
Monitoring
High
Waste handling, disposal, and treatment
E.5.4 Average Daily Concentration and Risk Estimation Calculations
This draft risk evaluation assesses asbestos exposures to workers and ONUs in occupational settings,
presented as an 8-hour TWA exposure. The 8-hour TWA exposures are then used to calculate ADCs for
chronic, non-cancer risks as well as ELCR estimates for chronic, lifetime cancer risks. ADC estimates
are used to calculate MOEs for chronic, non-cancer risks. For more detailed information regarding
occupational risk estimation calculations, see Asbestos Part 2 Draft RE - Risk Calculator for
Occupational Exposure - Fall 2023 (U.S. EPA. 20231).
E.5.4.1 Average Daily Concentration Calculations
ADC is used to estimate workplace exposures for non-cancer risk. These exposures are estimated as
follows:
EquationApx E-l.
EquationApx E-2.
Equation Apx E-3.
C x ED x EF x WY
ADC = ^
AT
EF = AWD X /
day hr
AT = WY x 365— x 24-
yr day
Where:
ADC =
Average daily concentration (8-hour TWA) used for chronic, non-cancer risk
calculations
C
Contaminant concentration in air (8-hour TWA)
ED
Exposure duration (hr/day)
EF
Exposure frequency (day/yr)
WY
Working years per lifetime (yr)
AT
Averaging time (hr) for chronic, non-cancer risk
AWD =
Annual working days (day/yr)
f
Fractional working days with exposure (unitless)
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The lifetime working years (WY) is defined as a triangular distribution with a minimum of 10.4 years, a
mode of 36 years, and a maximum of 44 years (U.S. Census Bureau. 2019a. b; U.S. BLS. 2014). The
corresponding 95th and 50th percentile values for this distribution are 40 years and 31 years,
respectively (Table_Apx E-5).
Table Apx E-5. Parameter Values for Calculating ADC
Parameter Name
Symbol
95th Percentile Value
50th Percentile Value
Unit
Exposure Duration
ED
8
8
hr/day
Annual Working Days
AWD
250
250
day/yr
Fractional Working Days with Exposure
f
1
1
unitless
Working Years per Lifetime
WY
40
31
yr
Averaging Time (chronic, non-cancer)
AT
350,400
271,560
hr
The subsections below (i.e., "Exposure Frequency", "Working Years", and "Body Weight") describe the
estimation of exposure frequency (EF) for each OES, as well as estimates for the number of working
years (WY).
Exposure Frequency (EF)
Exposure frequency (EF) is the number of days per year a worker is exposed to the chemical being
assessed. In some cases, it may be reasonable to assume a worker is exposed to the chemical on each
working day. In other cases, it may be more appropriate to estimate a worker's exposure to the chemical
occurs during a subset of the worker's annual working days. The relationship between exposure
frequency and annual working days can be described as shown in Equation Apx E-3.
For the Firefighting and other disaster response OES, the exposure frequency to ACM was estimated to
be between 1 to 3 days per year depending on whether the worker is a career or volunteer firefighter (see
Appendix E. 11.4.2). For the Maintenance, renovation, and demolition OES, the exposure frequency to
asbestos-containing material was estimated to be 50 days per year based annual working days and
fraction of days exposed (see Appendix E. 10.4.2). An exposure frequency of 250 days per year is
assumed for all other OESs in this draft risk evaluation.
BLS provides data on the total number of hours worked and total number of employees by each industry
NAICS code. These data are available from the 3- to 6-digit NAICS level (where 3-digit NAICS are less
granular and 6-digit NAICS are the most granular). Dividing the total, annual hours worked by the
number of employees yields the average number of hours worked per employee per year for each
NAICS.
EPA has identified approximately 140 NAICS codes applicable to the multiple COUs for the 10
chemicals undergoing risk evaluation. For each NAICS code of interest, EPA looked up the average
hours worked per employee per year at the most granular NAICS level available (i.e., 4-, 5-, or 6-digit).
EPA converted the working hours per employee to working days per year per employee assuming
employees work an average of 8 hours per day. The average number of days per year worked, or AWD,
ranges from 169 to 282 days per year, with a 50th percentile value of 250 days per year. EPA repeated
this analysis for all NAICS codes at the 4-digit level. The average AWD for all 4-digit NAICS codes
ranges from 111 to 282 days per year, with a 50th percentile value of 228 days per year. 250 days per
year is approximately the 75th percentile.
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In the absence of industry- and asbestos-specific data, EPA assumes the fraction of days exposed while
working is equal to one for all COUs.
Working Years (WY)
EPA has developed a triangular distribution for working years and defined the parameters of the
triangular distribution as follows:
• Minimum value: BLS CPS tenure data with current employer as a low-end estimate of the
number of lifetime working years (10.4 years);
• Mode value: The 50th percentile tenure data with all employers from the U.S. Census' (2016)
Survey of Income and Program Participation (SIPP) as a mode value for the number of lifetime
working years (36 years); and
• Maximum value: The maximum average tenure data with all employers from the SIPP as a high-
end estimate on the number of lifetime working years (44 years).
This triangular distribution has a 50th percentile value of 31 years and a 95th percentile value of 40
years. EPA uses these values for central tendency and high-end ADC calculations, respectively.
The U.S. BLS (2014) provides information on employee tenure with current employer obtained from the
Current Population Survey (CPS). CPS is a monthly sample survey of about 60,000 households that
provides information on the labor force status of the civilian non-institutional population ages 16 and
over; CPS data are released every two years. The data are available by demographics and by generic
industry sectors but are not available by NAICS codes.
The U.S. Census Bureau (2019a) Survey of Income and Program Participation (SIPP) provides
information on lifetime tenure with all employers. SIPP is a household survey that collects data on
income, labor force participation, social program participation and eligibility, and general demographic
characteristics through a continuous series of national panel surveys of between 14,000 and 52,000
households (U.S. Census Bureau. 2019a). EPA analyzed the 2008 SIPP Panel Wave 1, which began in
2008 and covers the interview months of September 2008 through December 2008 (U.S. Census Bureau.
2019a). For that panel, lifetime tenure data are available by Census Industry Codes, which can be
crosswalked with NAICS codes.
SIPP data include fields for the industry in which each surveyed, employed individual works
(TJBIND1), worker age (TAGE), and years of work experience with all employers over the surveyed
individual's lifetime.6 Census household surveys use different industry codes than the NAICS codes
used in its firm surveys, so these were converted to NAICS using a published crosswalk (U.S. Census
Bureau. 2012). EPA calculated the average tenure for the following age groups: (1) workers age 50 and
older; (2) workers age 60 and older; and (3) workers of all ages employed at time of survey. EPA used
tenure data for age group "50 and older" to determine the high-end lifetime working years, because the
sample size in this age group is often substantially higher than the sample size for age group "60 and
older." For some industries, the number of workers surveyed, or sample size, was too small to provide a
reliable representation of the worker tenure in that industry. Therefore, EPA excluded data from the
analysis where the sample size is less than five.
6 To calculate the number of years of work experience, EPA took the difference between the year first worked
(TMAKMNYR) and the current data year {i.e., 2008). The Agency then subtracted any intervening months when not working
(ETIMEOFF).
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7001
7002
7003
7004
7005
7006
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7009
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7012
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TableApx E-6 summarizes the average tenure for workers age 50 and older from the SIPP data.
Although the tenure may differ for any given industry sector, there is no significant variability between
the 50th and 95th percentile values of average tenure across manufacturing and non-manufacturing
sectors.
Table Apx E-6. Overview of Average Worker Tenure from U.S. Census SIPP (Age Group 50+)
Industry Sectors
Working Years
Average
50th Percentile
95th Percentile
Maximum
All industry sectors relevant to the 10
chemicals undergoing risk evaluation
35.9
36
39
44
Manufacturing sectors (NAICS 31-33)
35.7
36
39
40
Non-manufacturing sectors (NAICS 42-81)
36.1
36
39
44
Source: (U.S. BLS. 2016)
Note: Industries where sample size is less than five are excluded from this analysis.
BLS CPS data provides the median years of tenure that wage and salary workers had been with their
current employer. Table Apx E-7 presents CPS data for all demographics (men and women) by age
group from 2008 to 2012. To estimate the low-end value on number of working years, EPA uses the
most recent (2014) CPS data for workers age 55 to 64 years, which indicates a median tenure of 10.4
years with their current employer. The use of this low-end value represents a scenario where workers are
only exposed to the chemical of interest for a portion of their lifetime working years, as they may
change jobs or move from one industry to another throughout their career.
Table Apx E-7. Met
ian Years of Tenure with Current Employer by Age Group
Age
January 2008
January 2010
January 2012
January 2014
16 years and over
4.1
4.4
4.6
4.6
16 to 17 years
0.7
0.7
0.7
0.7
18 to 19 years
0.8
1.0
0.8
0.8
20 to 24 years
1.3
1.5
1.3
1.3
25 years and over
5.1
5.2
5.4
5.5
25 to 34 years
2.7
3.1
3.2
3.0
35 to 44 years
4.9
5.1
5.3
5.2
45 to 54 years
7.6
7.8
7.8
7.9
55 to 64 years
9.9
10.0
10.3
10.4
65 years and over
10.2
9.9
10.3
10.3
Source: (U.S. BLS. 2014)
E.5.4.2 Margin of Exposure and Excess Lifetime Cancer Risk Calculations
Chronic, Non-cancer Risk Estimation Using MOE
EPA used the calculated ADC values to estimate chronic, non-cancer exposure using Margin of
Exposures (MOE). The equation for calculating MOE is provided in Table Apx E-4 below and in Table
5-20.
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EquationApx E-4.
MOEchronic
Non — cancer Hazard value (POD)
Human Exposure
Where:
MOE
Margin of exposure (unitless)
0.026 (f/cc) (See Table 5-20)
ADC estimate for the relevant occupational exposure scenario
from the exposure assessment (f/cc)
Hazard value (POD)
Raman exposure
The calculated MOE value for an exposure scenario was compared to a benchmark MOE that was
calculated using uncertainty factors (UF) that account for variation in sensitivity within human
populations (see Table 5-20). The MOE estimate was interpreted as human health risk if the
MOE estimate was less than the benchmark MOE (i.e., the total UF) of 300. On the other hand, the
MOE estimate indicated negligible concerns for adverse human health effects if the MOE
estimate exceeded this benchmark MOE. Typically, the larger the MOE, the more unlikely it is
that a non-cancer adverse effect would occur.
Chronic, Cancer Risk Estimation Using ELCR
EPA commonly estimates extra cancer risks for repeated exposures to a chemical using an equation
format where Risk = Human Exposure (e.g., 8-hour TWA concentration) x IUR. Estimates of extra
cancer risks would be interpreted as the incremental probability of an individual developing cancer over
a lifetime as a result of exposure to the potential carcinogen (i.e., incremental or extra individual lifetime
cancer risk).
However, as discussed in Section 3.2 of the Part 1 Risk Evaluation for Asbestos, assessment of asbestos
is unique due to the relation of exposure timing to cancer outcome. The time since first exposure plays a
dominant role in modeling risk. The most relevant exposures used in understanding mesothelioma risk
were those that occurred decades prior to the onset of cancer and subsequent cancer progression. For this
reason, EPA has used a less than lifetime exposure calculation (see Section 4.2.1 of the Part 1 Risk
Evaluation for Asbestos for additional information).
The equations for Excess Lifetime Cancer Risk (ELCR) are provided in Table 5-20. These equations can
also be used for estimating cancer risks for less than lifetime exposure from inhalation of asbestos, as
shown in the Office of Land and Emergency Management Framework for Investigating Asbestos-
contaminated SaperfandSites (U.S. EPA. 2008).
To estimate risk, ELCR values were calculated for each similar exposure group and occupational
exposure scenario and compared to a benchmark value of 1 x 10~4. The ELCR value was determined a
human health risk if the estimate was greater than this benchmark value. ELCR estimates under this
benchmark indicated negligible human health concerns. Typically, the smaller the ELCR estimate, the
more unlikely it is that a cancer-related adverse health effect would occur. The process for estimating
ELCR values is explained in further detail in Equation Apx E-5 below.
Equation Apx E-5.
ELCR= EPCx TWFx IURltl
Where:
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ELCR = Excess Lifetime Cancer Risk, the risk of developing cancer as a consequence of
the site-related exposure
EPC = Exposure Point Concentration, the concentration of asbestos fibers in air (f/cc) for
the specific activity being assessed
IURltl = Less than lifetime Inhalation Unit Risk per f/cc
TWF = Time-weighted factor that accounts for less-than-continuous exposure during a 1-
year exposure.7 This parameter is calculated using EquationApx E-6 below:
EquationApx E-6.
Exposure time (hours per day) Exposure frequency (days per year)
( 24 hours ^ ^ 365 days ^
Equation Apx E-7.
EF = AWD X /
Where:
EF = Exposure frequency (day/yr)
AWD = Annual working days (day/yr)
F = Fractional working days with exposure (unitless)
Equation Apx E-7 above can be extended for more complex exposure scenarios by computing the TWA
exposure of multiple exposures (e.g., for 30-minute task samples within a full 8-hour shift). Similarly,
when multiple exposures may each have different risks, those may be added together (e.g., for episodic
exposures during and between asbestos removal work). It is important to note that the short-term
inhalation exposure estimates of ELCR are adjusted to account for a 30-minute exposure at the short-
term concentration and a 7.5-hour exposure at the 8-hour TWA concentration. For example, if the short-
term (30-minute) inhalation monitoring data leads to high end exposure of 0.1 f/cc, and the high end 8-
hour TWA monitoring data for the same OES is 0.01 f/cc, then the 8-hour TWA adjustment for the high
end short-term exposure point concentration would be calculated as EPCsimTWA adj = [(0.5 hr)(0.1 f/cc) +
(7.5)(0.01 f/cc)] / 8 hr) = 0.016 f/cc.
When exposures of full-shift occupational workers are to be evaluated, the TWF should be adjusted to
account for differences in inhalation volumes between workers and non-workers. EPA assumes workers
breathe 10 m3 air during an 8-hour shift and non-workers breathe 20 m3 in 24 hours (U.S. EPA. 2009).
The hourly ratio of those breathing volumes is the volumetric adjustment factor for workers (V(worker))
[(10/8) / (20/24) = 1.5], Thus, for workers, the formula, ELCR = EPC x TWF x IURltl, is extended as
ELCR = EPC x TWF x V x IURltl, where TWF(worker) = (8 hr / 24 hr) x (EF / 365 days), and
V(worker) =1.5.
EPA assumes that a worker in the United States is at least 16 years of age, and the 95th percentile value
for the number of working years is 40 years (see subsection titled "Working Years" below). Therefore,
EPA considers a less-than-lifetime IUR value corresponding to an individual that is first exposed at 16
years old and experiences regular exposure over 40 years (i.e., IUR(16, 40)). As described in Appendix
K of this risk evaluation, the IUR( 16,40) = 0.08 per f/cc. Therefore, the excess lifetime cancer risk from
occupational settings is computed as follows: ELCR = (EPC) x (8 hr / 24 hr) x (EF / 365 days) x (1.5) x
(0.08 per f/cc).
7 See U.S. EPA (1994) and Part F update to RAGS inhalation guidance U.S. EPA (2009).
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The EPC is calculated as the 8-hour TWA inhalation monitoring concentration, which is adjusted for the
short-term inhalation monitoring values as described above.
E.6 Consideration of Engineering Controls and Personal Protective
Equipment
OSHA and NIOSH recommend employers utilize the hierarchy of controls to address hazardous
exposures in the workplace. The hierarchy of controls strategy outlines, in descending order of priority,
the use of elimination, substitution, engineering controls, administrative controls, and lastly personal
protective equipment (PPE). The hierarchy of controls prioritizes the most effective measures first which
is to eliminate or substitute the harmful chemical (e.g., use a different process, substitute with a less
hazardous material), thereby preventing or reducing exposure potential. Following elimination and
substitution, the hierarchy recommends engineering controls to isolate employees from the hazard,
followed by administrative controls, or changes in work practices to reduce exposure potential (e.g.,
source enclosure, local exhaust ventilation systems). Administrative controls are policies and procedures
instituted and overseen by the employer to protect worker exposures. As the last means of control, the
use of personal protective equipment (e.g., respirators, gloves) is recommended, when the other control
measures cannot reduce workplace exposure to an acceptable level.
E.6.1 Respiratory Protection
OSHA's Respiratory Protection Standard (29 CFR 1910.134) requires employers in certain industries to
address workplace hazards by implementing engineering control measures and, if these are not feasible,
provide respirators that are applicable and suitable for the purpose intended. Respirator selection
provisions are provided in section 1910.134(d) and require that appropriate respirators are selected based
on the respiratory hazard(s) to which the worker will be exposed and workplace and user factors that
affect respirator performance and reliability. Assigned protection factors (APFs) are provided in Table 1
under section 1910.134(d)(3)(i)(A) (see below in TableApx E-8) and refer to the level of respiratory
protection that a respirator or class of respirators is expected to provide to employees when the employer
implements a continuing, effective respiratory protection program according to the requirements of
OSHA's Respiratory Protection Standard.
If respirators are necessary in atmospheres that are not immediately dangerous to life or health, workers
must use NIOSH-certified air-purifying respirators or NIOSH-approved supplied-air respirators with the
appropriate APF. Respirators that meet these criteria include air-purifying respirators with organic vapor
cartridges. Respirators must meet or exceed the required level of protection listed in Table Apx E-8.
Based on the APF, inhalation exposures may be reduced by a factor of 5 to 10,000, if respirators are
properly worn and fitted.
However for asbestos, nominal APFs in Table Apx E-8 may not be achieved for all PPE users (Riala
andRiipinen. 1998) investigated performance of respirators and HEP A units in 21 different exposure
abatement scenarios; most involved very high exposures not consistent with COUs identified in this RE.
However, for three abatement scenarios, exposure concentrations were below 1 f/cc, which is relevant to
the COUs in this draft risk evaluation. In the three scenarios with nominal APF 2,000, actual APFs were
reported as 50, 5, and 4. The strength of this publication is the reporting of asbestos samples inside the
mask, use of worker's own protective equipment, and measurement in different real work conditions.
The results demonstrate that while some workers have protection above nominal APF, some workers
have protection below nominal APF, so even with every worker wearing a respirator, some of these
workers would not be protected.
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Table Apx E-8. Assigned Protection Factors for Respirators in OSHA Standard 29 CFR 1910.134
Type of Respirator
Quarter
Half
Full
Helmet/
Loose-Fitting
Mask
Mask
Facepiece
Hood
Facepiece
1. Air-Purifying Respirator
5
10
50
2. Power Air-Purifying Respirator (PAPR)
50
1,000
25/1,000
25
3. Supplied-Air Respirator (SAR) or Airline Respirator
• Demand mode
10
50
• Continuous flow mode
50
1,000
25/1,000
25
• Pressure-demand or other positive-pressure
mode
50
1,000
4. Self-Contained Breathing Apparatus (SCBA)
• Demand mode
10
50
50
• Pressure-demand or other positive-pressure
mode (e.g., open/closed circuit)
10,000
10,000
Source: 29 CFR 1910.134(d)(3)(i)(A)
NIOSH and BLS conducted a voluntary survey of U.S. employers regarding the use of respiratory
protective devices between August 2001 and January 2002 (NIOSH. 2003). The survey was sent to a
sample of 40,002 establishments designed to represent all private sector establishments. The survey had
a 75.5 percent response rate (NIOSH. 2003). A voluntary survey may not be representative of all private
industry respirator use patterns as some establishments with low or no respirator use may choose to not
respond to the survey. Therefore, results of the survey may potentially be biased towards higher
respirator use.
NIOSH and BLS estimated about 619,400 establishments used respirators for voluntary or required
purposes (including emergency and non-emergency uses). About 281,800 establishments (45 percent)
were estimated to have had respirator use for required purposes in the 12 months prior to the survey. The
281,800 establishments estimated to have had respirator use for required purposes were estimated to be
approximately 4.5 percent of all private industry establishments in the United States at that time
(NIOSH. 2003).
The survey found that the establishments that required respirator use had the following respirator
program characteristics (NIOSH. 2003):
• 59 percent provided training to workers on respirator use;
• 34 percent had a written respiratory protection program;
• 47 percent performed an assessment of the employees' medical fitness to wear respirators; and
• 24 percent included air sampling to determine respirator selection.
The survey report does not provide a result for respirator fit testing or identify if fit testing was included
in one of the other program characteristics.
Of the establishments that had respirator use for a required purpose within the 12 months prior to the
survey, NIOSH and BLS found (NIOSH. 2003):
• non-powered air purifying respirators are most common, 94 percent overall and varying from 89
to 100 percent across industry sectors;
• powered air-purifying respirators represent a minority of respirator use, 15 percent overall and
varying from 7 to 22 percent across industry sectors; and
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• supplied air respirators represent a minority of respirator use, 17 percent overall and varying
from 4 to 37 percent across industry sectors.
Of the establishments that used non-powered air-purifying respirators for a required purpose within the
12 months prior to the survey, NIOSH and BLS found (NIOSH. 2003) that a
• high majority use dust masks, 76 percent overall and varying from 56 to 88 percent across
industry sectors;
• varying fraction use half-mask respirators, 52 percent overall and varying from 26 to 66 percent
across industry sectors; and
• varying fraction use full-facepiece respirators, 23 percent overall and varying from 4 to 33
percent across industry sectors.
TableApx E-9. summarizes the number and percent of all private industry establishments and
employees that used respirators for a required purpose within the 12 months prior to the survey and
includes a breakdown by industry sector (NIOSH. 2003).
Table Apx E-9. Number and Percent of Establishments and Employees Using Respirators within
12 Months Prior to Survey
Industry
Establishments
Employees
Number
Percent of All
Establishments
Number
Percent of All
Employees
Total Private Industry
281,776
4.5
3,303,414
3.1
Agriculture, forestry, and fishing
13,186
9.4
101,778
5.8
Mining
3,493
11.7
53,984
9.9
Construction
64,172
9.6
590,987
8.9
Manufacturing
48,556
12.8
882,475
4.8
Transportation and public utilities
10,351
3.7
189,867
2.8
Wholesale Trade
31,238
5.2
182,922
2.6
Retail Trade
16,948
1.3
118,200
0.5
Finance, Insurance, and Real Estate
4,202
0.7
22,911
0.3
Services
89,629
4.0
1,160,289
3.2
E.7 Evidence Integration for Environmental Releases and Occupational
Exposures
Evidence integration for the environmental release and occupational exposure assessment includes
analysis, synthesis and integration of information, and data to produce estimates of environmental
releases and occupational exposures. During evidence integration, EPA considered the likely location,
duration, intensity, frequency, and quantity of releases and exposures while also considering factors that
increase or decrease the strength of evidence when analyzing and integrating the data. Key factors EPA
considered when integrating evidence includes the following:
1. Data Quality: EPA only integrated data or information rated as high, medium, or low obtained
during the data evaluation phase. Data and information rated as iminformative are not used in
exposure evidence integration. In general, higher rankings are given preference over lower
rankings; however, lower ranked data may be used over higher ranked data when specific aspects
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of the data are carefully examined and compared. For example, a lower ranked data set that
precisely matches the OES of interest may be used over a higher ranked study that does not as
closely match the OES of interest.
2. Data Hierarchy: EPA used both measured and modeled data to obtain accurate and
representative estimates (e.g., central-tendency, high-end) of the environmental releases and
occupational exposures resulting directly from a specific source, medium, or product. If
available, measured release and exposure data are given preference over modeled data, with the
highest preference given to data that are both chemical-specific and directly representative of the
OES/exposure source.
EPA considered both data quality and data hierarchy when determining evidence integration strategies.
For example, EPA may have given preference to high quality modeled data directly applicable to the
OES being assessed over low quality measured data that is not specific to the OES. The final integration
of the environmental release and occupational exposure evidence combined decisions regarding the
strength of the available information, including information on plausibility and coherence across each
evidence stream.
EPA evaluated environmental releases based on reported release data from standard engineering sources
such as TRI, NEI, and NRC. EPA estimated COU-specific releases where supporting data existed and
documented uncertainties where an absence of such data required a broader application of release
estimates.
EPA evaluated occupational exposures based on monitoring data and worker activity information from
standard engineering sources and systematic review. EPA used COU-specific assessment approaches
where supporting data existed and documented uncertainties where supporting data were only applicable
for broader assessment approaches.
E.8 Weight of Scientific Evidence Ratings for Environmental Release
Estimates by PES
For each OES, EPA considered the assessment approach, the quality of the data and models, and the
strengths, limitations, assumptions, and key sources of uncertainties in the assessment results to
determine a weight of scientific evidence rating. EPA considered factors that increase or decrease the
strength of the evidence supporting the release estimate—including quality of the data/information,
applicability of the release or exposure data to the OES (including considerations of temporal relevance,
locational relevance) and the representativeness of the estimate for the whole industry. The best
professional judgment is summarized using the descriptors of robust, moderate, slight, or indeterminant,
according to EPA's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (U.S. EPA. 2021). For example, a conclusion of moderate is appropriate where there is
measured release data from a limited number of sources such that there is a limited number of data
points that may not cover most or all the sites within the OES. A conclusion of slight is appropriate
where there is limited information that does not sufficiently cover all sites within the OES, and the
assumptions and uncertainties are not fully known or documented. See EPA's Application of Systematic
Review in TSCA Risk Evaluations (U.S. EPA. 2021) for additional information on weight of scientific
evidence conclusions.
Weight of scientific evidence ratings for the environmental release estimates for each OES are provided
in Table 3-8. Weight of scientific evidence ratings for all OES are also summarized in Table Apx E-10,
as well as the rationale for each rating.
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7268 Table Apx E-10. Summary of Assumptions, Uncertainty, and Overall Confidence in Release Estimates by PES
OES
Weight of Scientific
Evidence Judgement
Rationale
Handling asbestos-
containing building
materials during
maintenance,
renovation, and
demolition activities
Moderate to Robust
EPA used TRI, NEI, NRC data, and literature data to assess environmental releases. TRI, NEI, NRC
data have medium, high, and medium overall data quality determinations from the systematic review
process, respectively. The literature data used in estimating releases have medium/high overall data
quality determinations. The use of these sources falls under monitoring/measured data, which is most
preferred based on the hierarchy of approaches. The primary strength of these estimates is that EPA
used multiple years of data in the analysis. A strength of TRI data is that TRI compiles the best
readily available release data for all reporting facilities. A strength of NEI data is that it includes
comprehensive and detailed estimates of air emissions from point and area sources. A strength of
NRC data is that it is the designated federal point of contact for reporting all spills of CERCLA
hazardous chemicals, such as asbestos, so it is likely to be a comprehensive data set. A strength of
literature search data is that all the underlying literature sources received data quality ratings of
medium or higher. The primary limitation to this assessment is that information on the conditions of
use of asbestos at facilities in TRI & NEI is limited, and NRC does not provide the condition of use of
asbestos at facilities. Additional limitations to this assessment are that EPA made assumptions on the
number of operating days to estimate daily releases and the uncertainty in the mapping of reporting
facilities to this OES. Based on this information, EPA has concluded that the weight of scientific
evidence for this assessment is moderate to robust and provides a plausible estimate of releases in
consideration of the strengths and limitations of reasonably available data.
Handling asbestos-
containing building
materials during
firefighting or other
disaster response
activities
Moderate
No OES-specific data was available to assess environmental releases. Therefore, EPA used surrogate
data from the Handling Asbestos-Containing Building Materials During Maintenance, Renovation,
and Demolition Activities OES. EPA assumed that the releases from an uncontrolled fire or clean up
would be similar to releases from demolition of a structure. While the surrogate monitoring data had
data quality ratings of medium/high, use of surrogate data may introduce uncertainties related to the
extent to which the surrogate OES and the OES being assessed are similar. Even though surrogate
data was used, the surrogate sources fall under monitoring/measured data, which is most preferred
based on the hierarchy of approaches. Based on this information, EPA has concluded that the weight
of scientific evidence for this assessment is moderate and provides a plausible estimate of releases in
consideration of the strengths and limitations of reasonably available data.
Use, repair, or removal
of industrial and
commercial appliances
or machinery
containing asbestos
Moderate to Robust
EPA used TRI and NEI data to assess environmental releases. These data sources have medium and
high overall data quality determinations from the systematic review process, respectively. The use of
TRI and NEI data falls under monitoring/measured data, which is most preferred based on the
hierarchy of approaches. The primary strength of these estimates is that EPA used multiple years of
data in the analysis. A strength of TRI data is that TRI compiles the best readily available release data
for all reporting facilities. A strength of NEI data is that it includes comprehensive and detailed
estimates of air emissions from point and area sources. The primary limitation to this assessment is
that information on the conditions of use of asbestos at facilities in TRI & NEI is limited. Additional
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OES
Weight of Scientific
Evidence Judgement
Rationale
limitations to this assessment are that EPA made assumptions on the number of operating days to
estimate daily releases, assumption of no wastewater discharges where not reported in TRI, and the
uncertainty in the mapping of reporting facilities to this OES. Based on this information, EPA has
concluded that the weight of scientific evidence for this assessment is moderate to robust and
provides a plausible estimate of releases in consideration of the strengths and limitations of
reasonably available data.
Handling articles or
formulations that
contain asbestos
Moderate to Robust
EPA used TRI and NEI data to assess environmental releases. These data sources have medium and
high overall data quality determinations from the systematic review process, respectively. The use of
TRI and NEI data falls under monitoring/measured data, which is most preferred based on the
hierarchy of approaches. The primary strength of these estimates is that EPA used multiple years of
data in the analysis. A strength of TRI data is that TRI compiles the best readily available release data
for all reporting facilities. A strength of NEI data is that it includes comprehensive and detailed
estimates of air emissions from point and area sources. The primary limitation to this assessment is
that information on the conditions of use of asbestos at facilities in TRI & NEI is limited. Additional
limitations to this assessment are that EPA made assumptions on the number of operating days to
estimate daily releases, assumption of no wastewater discharges where not reported in TRI, and the
uncertainty in the mapping of reporting facilities sites to this OES. Based on this information, EPA
has concluded that the weight of the scientific evidence for this assessment is moderate to robust and
provides a plausible estimate of releases in consideration of the strengths and limitations of
reasonably available data.
Waste handling,
disposal, and treatment
Moderate to Robust
EPA used TRI and NEI data to assess environmental releases. These data sources have medium and
high overall data quality determinations from the systematic review process, respectively. The use of
TRI and NEI data falls under monitoring/measured data, which is most preferred based on the
hierarchy of approaches. The primary strength of these estimates is that EPA used multiple years of
data in the analysis. A strength of TRI data is that TRI compiles the best readily available release data
for all reporting facilities. A strength of NEI data is that it includes comprehensive and detailed
estimates of air emissions from point and area sources. The primary limitation to this assessment is
that information on the conditions of use of asbestos at facilities in TRI & NEI is limited. Additional
limitations to this assessment are that EPA made assumptions on the number of operating days to
estimate daily releases, assumption of no wastewater discharges where not reported in TRI, and the
uncertainty in the mapping of reporting facilities to this OES. Based on this information, EPA has
concluded that the weight of scientific evidence for this assessment is moderate to robust and
provides a plausible estimate of releases in consideration of the strengths and limitations of
reasonably available data.
7269
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E.9 Weight of Scientific Evidence Ratings for Inhalation Exposure
Estimates by PES
For each OES, EPA considered the assessment approach, the quality of the data and models, and the
strengths, limitations, assumptions, and key sources of uncertainties in the assessment results to
determine a weight of scientific evidence rating. EPA considered factors that increase or decrease the
strength of the evidence supporting the release estimate—including quality of the data/information,
applicability of the release or exposure data to the OES (including considerations of temporal relevance,
locational relevance) and the representativeness of the estimate for the whole industry. The best
professional judgment is summarized using the descriptors of robust, moderate, slight, or indeterminant,
according to EPA's Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2021). For
example, a conclusion of moderate is appropriate where there is measured release data from a limited
number of sources such that there is a limited number of data points that may not cover most or all the
sites within the OES. A conclusion of slight is appropriate where there is limited information that does
not sufficiently cover all sites within the OES, and the assumptions and uncertainties are not fully
known or documented. See EPA's Application of Systematic Review in TSCA Risk Evaluations (U.S.
EPA. 2021) for additional information on weight of scientific evidence conclusions. Table Apx E-l 1
provides a summary of EPA's overall confidence in its inhalation exposure estimates for each of the
OESs assessed.
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Table Apx E-ll. Summary of Assumptions, Uncertainty, and Overall Confidence in Inhalation Exposure Estimates by PES
OES
Weight of Scientific
Evidence
Judgement
Rationale
Handling asbestos-
containing building
materials during
maintenance,
renovation, and
demolition activities
Moderate
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results
to determine a weight of scientific evidence conclusion for the 8-hour TWA inhalation exposure
estimates. Monitoring data from published literature and OSHA's CEHD were used to estimate
inhalation exposure for this OES. These monitoring data include 513 personal TWA samples and have an
overall data quality determination of medium. The primary strength is the use of directly applicable
monitoring data, which is preferrable to other assessment approaches such as modeling or the use of
occupational exposure limits. The primary limitations of these data include uncertainty in mapping
OSHA CEHD to this OES based on the SIC codes in the data set, lack of worker activity descriptions in
the data set, uncertainty in the representativeness of the monitoring data for all sites in this OES, and
number of non-detects (-40 percent of the TWA data were non-detect for asbestos). Based on this
information, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures in consideration of the strengths and limitations of
reasonably available data.
Handling asbestos-
containing building
materials during
firefighting or other
disaster response
activities
Moderate to Robust
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results
to determine a weight of scientific evidence conclusion for the 8-hour TWA inhalation exposure
estimates. Monitoring data from published literature were used to estimate inhalation exposure for this
OES. These monitoring data include 60 personal breathing zone samples and have an overall data quality
determination of medium/high. The primary strength is the use of directly applicable monitoring data,
which is preferrable to other assessment approaches such as modeling or the use of occupational
exposure limits. An additional strength is that the literature sources include information on worker
activities. A primary limitation is that several of the literature sources do not provide discrete sampling
values, with one only providing summary statistics for two groups of 636 and 114 samples. An additional
limitation is the uncertainty in whether the activities performed in this study accurately reflect all
firefighting scenarios or the disaster response scenario as a whole. Additionally, there is uncertainty in
EPA's assumption of exposure frequency and exposure duration. Based on this information, EPA has
concluded that the weight of scientific evidence for this assessment is moderate to robust and provides a
plausible estimate of exposures in consideration of the strengths and limitations of reasonably available
data.
Use, repair, or
removal of industrial
and commercial
appliances or
machinery
containing asbestos
Moderate to Robust
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results
to determine a weight of scientific evidence conclusion for the 8-hour TWA inhalation exposure
estimates. Monitoring data from published literature were primarily used to estimate inhalation exposure
for this OES, along with five personal breathing zone data points from OSHA's CEHD. These
monitoring data include 236 personal breathing zone TWA samples and have an overall data quality
determination of high. The primary strength is the use of directly applicable monitoring data, which is
preferrable to other assessment approaches such as modeling or the use of occupational exposure limits.
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OES
Weight of Scientific
Evidence
Judgement
Rationale
An additional strength is that the literature sources include information on worker activities. A primary
limitation is that several of the literature sources do not provide discrete sampling values, with one only
providing summary statistics for two groups of 59 and 47 samples. An additional limitation is the
uncertainty in whether the activities performed in this study accurately reflect all use, repair, or removal
of appliances or machinery scenario. Based on this information, EPA has concluded that the weight of
scientific evidence for this assessment is moderate to robust and provides a plausible estimate of
exposures in consideration of the strengths and limitations of reasonably available data.
Handling articles or
formulations that
contain asbestos
Moderate
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results
to determine a weight of scientific evidence conclusion for the 8-hour TWA inhalation exposure
estimates. Monitoring data from published literature were primarily used to estimate inhalation exposure
for this OES, along with 13 personal breathing zone and area sampling data points from OSHA's CEHD.
The monitoring data include a total of 47 personal breathing zone TWA samples and have an overall data
quality determination of high. The primary strength is the use of directly applicable monitoring data,
which is preferrable to other assessment approaches such as modeling or the use of occupational
exposure limits. An additional strength is that the literature sources include information on worker
activities. The primary limitations of these data include uncertainty in mapping OSHA CEHD to this
OES based on the SIC codes in the data set, lack of worker activity descriptions in the OSHA CEHD data
set, uncertainty in the representativeness of the monitoring data for all sites in this OES, and the number
of non-detects (all of the TWA data from OSHA's CEHD were non-detect for asbestos). Based on this
information, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures in consideration of the strengths and limitations of
reasonably available data.
Waste handling,
disposal, and
treatment
Moderate
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results
to determine a weight of scientific evidence conclusion for the 8-hour TWA inhalation exposure
estimates. Monitoring data from published literature and OSHA's CEHD were used to estimate
inhalation exposure for this OES. This monitoring data includes 95 personal TWA samples and have an
overall data quality determination of high. The primary strength is the use of directly applicable
monitoring data, which is preferrable to other assessment approaches such as modeling or the use of
occupational exposure limits. The primary limitations of these data include uncertainty in mapping
OSHA CEHD to this OES based on the SIC codes in the data set, lack of worker activity descriptions in
the data set, uncertainty in the representativeness of the monitoring data for all sites in this OES, number
of non-detects (-40 percent of the TWA data were non-detect for asbestos), and age of the monitoring
data. Based on this information, EPA has concluded that the weight of scientific evidence for this
assessment is moderate and provides a plausible estimate of exposures in consideration of the strengths
and limitations of reasonably available data.
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E.10 Handling Asbestos-Containing Building Materials During
Maintenance, Renovation, and Demolition Activities
E.10.1 Process Description
Until the Asbestos Ban and Phaseout Rule of the late 1980s, various asbestos-containing construction
materials were manufactured or imported into the U.S. and subsequently used in the construction of
commercial and public buildings numbering in the hundreds of thousands. Older buildings in the United
States may still house ACM, and workers may come into contact with dust-producing or "friable"
asbestos when performing different activities involved in the renovation, maintenance, or demolition
processes (Paustenbach et al.. 2004). Workers with higher exposure potential to asbestos include
carpenters, joiners, shopfitters, plumbers, gas service engineers, electricians, computer cabling installers,
janitors, handymen, demolition workers, and repairers (SLIC. 2006). In a study conducted in 1984, EPA
estimated that 20 percent of U.S. commercial and public buildings (more than 700,000) contain asbestos
material in friable form; however, it is unknown how many of these buildings are still standing (U.S.
EPA. 1988a).
Worker exposures to and environmental releases of asbestos may occur when older buildings are being
remodeled or renovated, or when they are being partially or completely demolished. Before remodeling,
renovation, and demolition activities begin, the ACM must be removed from the structure. Exposure
concerns arise from the disturbance of the ACM during the removal and disposal process. However,
worker exposures to asbestos during the construction of new structures, or building additions onto
existing structures, are possible but less likely than exposures to asbestos from refurbishing existing
structures.
For the purposes of evaluating worker exposure risk in this assessment, workers that may be exposed to
asbestos-containing legacy construction materials have been divided into three similar exposure groups
(SEGs):
1. Higher Exposure-Potential Workers - workers who may directly generate friable asbestos
through actions such as grinding, sanding, cutting, or abrading;
2. Lower Exposure-Potential Workers - workers who may come into direct contact with friable
asbestos while performing their required work activities; and
3. ONUs - workers who may be in the vicinity of asbestos but are unlikely to have direct contact
with ACM.
Renovation and demolition operations at all sites, with the exception of residential buildings with four or
fewer units, are regulated under the Clean Air Act's National Emission Standards for Hazardous Air
Pollutants (NESHAP) (U.S. EPA. 1990a). The NESHAP requires the owner or operator of the facility to
perform an asbestos inspection of the area being worked on before performing any renovation or
demolition to scope out any hazards or ACM. If asbestos is found, a risk assessment is performed and a
management plan is created (SLIC. 2006).
When ACM is found in a commercial or public building, the asbestos NESHAP requires at least one
person must be on-site that is trained in the work practices specified by the NESHAP, and a contractor
specialized in asbestos removal is required to perform the removal. The regulation requires work
practices that lower the emission potential for asbestos, such as removing all ACM, adequately wetting
all regulated asbestos-containing materials, sealing the material in leak tight containers and disposing of
the asbestos-containing waste material as efficiently as possible (U.S. EPA. 1990a).
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The asbestos concentrations of common previously used (legacy) asbestos-containing materials that
workers may come into contact with when working in older buildings are listed in TableApx E-12
below.
Table Apx E-12. Asbestos Concentrat
tions for Common Legacy Construction Materials
Product Category
Percentage
Form of
Asbestos
Source
Insulation Products (including spray)
12-100
C, A, Cr
(IPCS. 1986)
Vinyl Floor Tile
5-25
C
(Racine, 2010)
Asbestos-Cement Building Products
10-15
C, A, Cr
(IPCS. 1986)
Asbestos-Cement Pipes
12-15
C, A, Cr
(IPCS. 1986)
Asbestos Millboard
45-98
C
(Banks. 1991)
Insulation Boards
25-40
A and C
(IPCS. 1986)
Textile Products
65-100
C and Cr
(IPCS. 1986)
Roofing materials
5-10
C
(Lanse and Thomulka, 2000b)
C = chrysotile; A = amosite; Cr = crocidolite
The general process for removing ACM during renovation operations first involves clearing any
furniture and materials from the area being renovated. Plastic sheeting is used to cover the walls and
create a barrier, and all means of air flow into the area are sealed to create a containment zone (Racine.
2010). The work environment is put under negative pressure and air filtration devices equipped with
high-efficiency particulate air (HEPA) filters are positioned in or near the area so that any airborne
fibers are captured before being discharged into the environment. ACM is treated with a water and/or
wetting agent solution to minimize fiber release. If the material will not absorb the wetting agent, a dry
removal using Type C respiratory protection is appropriate (Banks. 1991). After asbestos removal is
complete, the ACM is appropriately disposed of and landfilled.
Encapsulation and enclosure are commonly used techniques to prevent friable asbestos from being
released during removal or before demolition. Encapsulation involves spraying the ACM with a sealant
that either penetrates and hardens the asbestos material or covers the surface of the material with a
protective coating. Both types of sealants are applied using airless spray equipment at low pressure to
reduce fiber release during application. Enclosure involves the construction of airtight walls and ceilings
around the ACM to create a barrier between the ACM and the building environment (i.e., corrugated
metal or polyvinyl chloride installed around ACM insulated piping). A combination of encapsulation
and enclosure are often required for maximum protection during removal (Banks. 1991). These work
practices may have changed since they were reportedly used; this will be further investigated during the
risk evaluation.
The specific processes for handling and removing different asbestos-containing materials are described
below.
Asbestos Insulation
Although insulation manufactured and consumed in the U.S. presently does not contain asbestos, certain
types of insulation used in the 1980s and before contained asbestos at concentrations between 12 and
100 percent (see Table Apx E-12). General removal activities are described above. Friable ACM is
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disposed in leak tight containers, typically 6 mil (0.006 in thickness) polyethylene bags, which can be
placed in 55-gallon drums for additional protection (Banks. 1991).
In a study for remediation of spray-on asbestos insulation from the ceiling of a large building in Yale, 92
tons of wet ACM was removed during a 20-day operation. A total of 40 workers were involved in the
project (Sawyer. 1977). However, this is just one example and may not be representative of the entire
industry.
Floor Tile
Vinyl floor tiling manufactured before 1980 may contain asbestos at concentrations from 5 to 25 percent
(see TableApx E-12). Removal of floor tiles containing asbestos is generally performed using one of
two different methodologies.
In the chemical stripping method, general preparation steps are taken to secure the area and the floor is
then flooded or misted with water or a wetting agent to decrease the dust load. Tiles are removed using
wide wood chisels and hammers or spud bars to pry up tiles without breakage (Perez et al.. 2018). Floor
tiles are then placed into disposal bags and loaded into a dumpster for delivery to an appropriately
licensed landfill. Following floor tile removal, a chemical mastic removal liquid is spread onto the floor
and subsequently agitated using a low-speed buffer. An absorbent is applied to the floor and mixed to
form a semi-solid, which is then scooped into disposal bags. Lastly, the floor is mopped and allowed to
air dry (Racine. 2010).
The wet grinding methodology shares similar floor preparation steps with the chemical stripping
method, but methods of mastic removal differ (Racine. 2010). At the start of the floor tile mastic
removal activity, the floor is flooded with water and a small amount of fine sand. A floor tile buffer is
fitted with a hard steel mesh disc and applied to the sand and water mixture. Areas not reachable by the
buffer such as corners are hand scraped using a wire brush or scratch pad. This process also generates a
sludge mixture of the water, sand, and the mastic compound. The sludge is collected and containerized
similar to the chemical stripping methodology (Racine. 2010). Floor preparation, tile removal, and the
cleanup process can take 2 to 3 days. For protection, workers may wear half-mask respirators and
disposable suits (Perez et al.. 2018); however, PPE practices may not be consistent throughout industrial
and commercial workplaces.
Roofing
Asphalt shingles, plastics, and other roofing materials manufactured before 1980 may contain asbestos
at concentrations from 5 to 10 percent (see Table Apx E-12). Removal of roofing materials containing
asbestos is generally performed with adherence to the following practices.
Workers wet the roofing material before and during removal activities. Sections of the roofing materials
are cut out using a power saw and placed into a chute connected to a sealed dumpster (Mowat et al..
2007). Water is periodically dumped down the chute and into the dumpster to prevent the ACM from
drying.
In one study, work trials were carried out at several sites where 30 to 40 year old AC clad buildings
were re-roofed or demolished. In these trials, roof replacement was carried out by two to six men
working on top of the roof who repetitively unfastened and removed small sections (20 to 40 m2) of
asbestos-containing roofing and replaced it with steel roofing (Brown. 1988). In these trials, work was
conducted for 2 to 6 hours during which 50 to 100 m2 of roofing was replaced (Brown. 1988). However,
this is just one example and may not be representative of the entire industry.
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Asbestos Cement (A/C) Pipes
Asbestos Cement pipes manufactured before the 1980s may contain asbestos concentrations ranging
from 12 to 15 percent (see Table Apx E-12) and are conventionally remediated in one of three ways:
Cured-in place pipe (CIPP) lining, removal with open trenching, or the pipe is abandoned in place.
CIPP lining is used on pipes that are still in good condition and will be strong enough to withstand the
daily pressures of their intended use. It is sprayed on the interior of unbroken, inline pipes, and is used to
extend the useful life of the pipe. Open trenching is the practice under which the entire A/C pipe is
excavated and open to the air. After excavation, the A/C pipe is wet-cut into 6- and 8-foot sections using
a snap cutter or similar tool, wrapped for containment, and removed for disposal. Asbestos cement pipes
may also simply be abandoned in place, with the new pipeline laid in a separate area (U.S. EPA. 2019b).
Demolition
Demolition of older buildings may release fibers from not only friable asbestos but also nonfriable ACM
that becomes friable from rough handling. A 1995 study indicated approximately 44,000 commercial
buildings are demolished in the United States each year (Perkins et al.. 2007). The choice of demolition
method depends on the project conditions, site construction, sensitivity of the neighborhood, and
availability of equipment (Kakooei and Normohammadi. 2014). For smaller demolition projects,
workers may use hand tools, simple electrically or pneumatically powered tools such as picks, hammers,
wire cutting and welding cutters to break down the structure. For smaller jobs like this, typically 3 to 5
workers were involved and demolition and removal work took approximately 1 to 2 weeks per site
(Kakooei and Normohammadi. 2014). A common and economical method for demolishing one- or two-
story buildings is by using heavy equipment to push down the building and move the material inward.
For taller buildings, a crane and wrecking ball generally are used to begin the process (Perkins et al..
2007). For some structures, explosives may be used to perform the initial demolition (U.S. EPA. 1990a).
The general demolition process involves workers operating backhoes or front-end loaders to remove the
building in manageable pieces, then using the vehicles to break the building pieces down into smaller
and more uniform chunks (Perkins et al.. 2007). This waste is loaded onto trucks and transported to an
approved landfill.
Demolition operations at all sites, with the exception of residential buildings with four or fewer units,
are regulated under the asbestos NESHAP. The NESHAP also does not apply to demolition or
renovation operations where the minimum amount of material to be disturbed is less than 260 linear feet,
160 square feet, or 35 cubic feet (U.S. EPA. 1990a). NESHAP regulations require that all regulated
ACM (RACM) be removed prior to demolition. RACM includes all friable ACM and certain types of
nonfriable ACM. Nonfriable ACM has two categories under NESHAP. Category I: material such as
roofing that is not likely to become friable under demolition (not considered RACM if it is non-friable).
Category II nonfriable ACM covers ACM that is likely to become friable during the demolition process
(considered to be RACM if there is a high probability of the asbestos becoming friable) (Perkins et al..
2007). ACM may be categorized differently based on the method of demolition used. For example,
asbestos-cement may be considered a Category I material if the demolition method will not generate
significant damage; however, if a wrecking ball or explosion/implosion techniques are used it can be
considered to be a Category II and is subject to the provisions of the NESHAP (U.S. EPA. 1990a).
A 2007 study was conducted on a building demolition and a demolition of a city block that both
occurred in Fairbanks, Alaska in the 1990's. Building A was three-stories high and contained asbestos in
the form of joint compound in gypsum wallboard (GWB) (2400 m2 of wall, 2-3 percent chrysotile in the
joint compound), vinyl sheet flooring (560 m2, 2 to 3 percent chrysotile), and popcorn surfacing
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materials on the ceiling (1,400 m2, 5 percent chrysotile). Building A's upper floors were demolished
with a wrecking ball and a 1,120 m2 of GWB and joint compound which contained 5 to 8 percent
chrysotile asbestos. Building A's upper floors were demolished with a wrecking ball and a backhoe and
front-end loader were used to demolish the remaining structure. Waste was loaded into dump trucks and
set to a landfill; the whole process was completed over 8 days. Block B was primarily demolished using
a bulldozer and a front end loader and was completed over 3 days (Perkins et al.. 2007). However, this is
just one example and is likely not representative of all building demolitions.
E.10.2 Facility Estimates
CDR data were not available for this OES. Therefore, EPA used BLS and SUSB data to estimate the
number of establishments and workers. However, employees from one employment establishment may
work at many different work sites throughout the year. Therefore, the number of establishments
employing the workers is different than the number of sites where exposures and releases occur. EPA
assumed that establishments and workers potentially involved in maintenance, renovation, and
demolition activities are classified under the applicable NAICS codes listed in Table Apx E-19.
For estimating the number of sites for the OES, EPA assumed that the highest potential for asbestos
exposure to workers while performing demolitions. Literature search data was used to estimate the
number of sites by calculating the number of demolitions per year. EPA first calculated the volume of
demolition waste generated per year. An EPA report stated that 83,612,000 tons of construction and
demolition (C&D) waste was generated in 2003 (U.S. EPA. 2003 a). Out of this total, 64,612,000 tons
(77 percent) was commercial waste, and 19,000,000 tons (23 percent) was residential waste. EPA
assumed that this percentage was reflective of all asbestos demolition sites. A more recent report stated
that 188,800,000 tons of C&D waste were generated in 2018 (Tiseo. 2022). EPA assumed that the
percentage of the wastes from 2018 was the same as from the 2003 EPA report (i.e., 77 percent x
188,800,000 tons of C&D wastes = 145,900,000 tons of commercial C&D wastes and 23 percent x
188,800,000 tons of C&D wastes = 42,900,000 tons of residential C&D wastes).
Next, EPA estimated the amount of waste generated per commercial building demolished. First, EPA
compiled information on the surface area of commercial buildings. One literature source stated that there
were roughly 5,900,000 commercial buildings in 2018, which had a total square footage of 96.4 billion
square feet, for an average area of 16,300 square feet per building (EIA. 2022). Another report found
that 158 lb/ft2 of debris are generated during commercial building demolition (U.S. EPA. 2003a). EPA
multiplied the average area of commercial building space by the debris generation factor, resulting in an
average of 1,149 tons of C&D waste generated per commercial building demolished. Finally, to obtain
the number of commercial demolitions per year, EPA divided the estimated amount of commercial C&D
waste, 145,900,000 tons, by the 1,149 tons of waste per commercial building. The same process was
repeated for residential demolitions using the corresponding residential building values. This resulted in
a total of 106,993 residential building demolitions per year and 126,950 commercial demolitions per
year for a total of 233,943 demolition sites per year. To account for the number of buildings containing
asbestos, these values were multiplied by 20 percent based on a 1984 U.S. EPA study that estimated 20
percent of buildings contain friable asbestos (U.S. EPA. 1988a). The final estimate for the number of
sites in this OES is 21,399 commercial demolition sites and 25,390 residential demolition sites, or
46,789 total sites.
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E.10.3 Release Assessment
E.10.3.1 Environmental Release Points
EPA expects releases to occur during maintenance, renovation, and demolition activities. As stated in
the process description, environmental releases of asbestos may occur when older buildings are being
remodeled or renovated, or when they are being partially or completely demolished. Before remodeling,
renovation, and demolition activities begin, any ACM must be removed from the structure. Release
concerns arise from the disturbance of the ACM during the removal and disposal process.
E.10.3.2 Environmental Release Assessment Results
EPA estimated releases from this OES using TRI, NEI, and NRC data, and literature search data. Based
on the data, EPA expects asbestos releases to fugitive air, surface water, and landfill. TRI data were
available for water, air, and land disposals, NEI data were available for air emissions, and NRC data
were available for wastewater discharges.
Within the NRC data, EPA mapped all four provided data points to the Handling asbestos-containing
building materials during maintenance, renovation, and demolition activities OES based on the
"Description of Incident" field including demolition, abatement, or piping issues. EPA only included
estimates for asbestos releases that reached water sources. Finally, EPA estimated daily emissions for
this OES by calculating the 50th and 95th percentile of all reported annual releases and dividing the
results by 12 release days/yr determined in Appendix E.4.4.
To estimate land disposals, EPA used a number of other sources identified via literature search due to
the large number of demolitions per year and the low number of TRI reporters for demolition. Three
literature sources were used to estimate land disposals. One source included a table specifying the
surface area of various materials used in building construction (m2), and the average concentration of
asbestos in these materials (Zhang et al.. 2021). This data is presented in TableApx E-13 and
TableApx E-14.
Table Apx E-13. Area of Asbestos Waste per Material
Material
Building Type
Area of Asbestos Waste (m2)
Slate
Residential
9,911
Commercial
0
Gypsum cement
Residential
1,939
Commercial
197
Cement/wooden boards
Residential
116
Commercial
0
Gaskets
Residential
8.58
Commercial
0
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Table Apx E-14. Average Concentration of Asbestos in Building Materials
Material
Statistic
Concentration (%)
Slate
Average
12.3
Maximum
16.0
Gypsum cement
Average
5.0
Maximum
10.0
Cement/wooden
boards
Average
10.0
Maximum
14.0
Gaskets
Average
14.9
Maximum
15.0
Another two sources provided information on the density (in kg/m2) of these materials (ARGCO. 2022;
Ohio University. 2022). This data is presented in TableApx E-15.
Table Apx E-15. Density of Asbestos-Containing Materials
Material
Density (kg/m2)
Slate roofing (3/8")
73.2
Gypsum Cement
19.5
Wood Shingle
14.6
Gaskets
5.7
To calculate the amount of asbestos per building, the weight per unit area of each material was
multiplied by the surface area used in building construction, and the concentration of asbestos in the
material. This figure was then divided by the listed values for number of buildings (781) and the
percentage of buildings with ACM (34.3 percent) listed in Zhang et al. (2021) to remain consistent with
EPA's original estimates of buildings and percent of buildings containing ACM. Finally, all materials
specified in the literature were summed to calculate a total mass of asbestos in building waste in both
residential and commercial buildings.
Total annual asbestos land waste was calculated by multiplying the residential and commercial building
totals by their respective number of demolitions per year and summing the resulting estimates.
A summary of daily environmental release estimates by media for this OES are provided in Table 3-8. In
addition, Table Apx E-16, Table Apx E-17, and Table Apx E-18 below present a summary of annual
and daily releases estimates to water, air, and land, respectively. For the raw data set used in making
these estimations, see Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure
Data Tables - Fall 2023 (U.S. EPA. 2023iY
Table Apx E-16. Wastewater Discharge Summary for Maintenance, Renovation, and Demolition
Activities
Annual Wastewater Discharges
(kg/site-year)
Number of
Operating Days
Daily Wastewater Discharges (kg/site-day)
Central Tendency
High-End
Central Tendency
High-End
1.4
45
12
0.11
4
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7569
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7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
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Table Apx E-17. Air Emission Summary for Maintenance, Renovation, and Demolition Activities
Annual Fugitive
Emissions
(kg/site-year)
Annual Stack
Emissions
(kg/site-year)
Number
of
Operating
Days
Daily Fugitive
Emissions
(kg/site-day)
Daily Stack
Emissions
(kg/site-day)
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
9.1E-03
1.8
N/A
N/A
12
7.6E-04
0.15
N/A
N/A
Table Apx E-18. Land Release Summary for Maintenance, Renovation, and Demolition Activities
Annual Land Disposals (kg/site-
year)
Number of
Operating Days
Daily Land Disposals (kg/site-day)
Central Tendency
High-End
Central Tendency
High-End
4,935
9,764
12
411
814
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of these estimates is that EPA used multiple years of data in the analysis. A
strength of TRI data is that TRI compiles the best readily available release data for all reporting
facilities. A strength of NEI data is that it includes comprehensive and detailed estimates of air
emissions from point and area sources. A strength of NRC data is that it is the designated federal point
of contact for reporting all spills of CERCLA hazardous chemicals, such as asbestos, so it is likely to be
a comprehensive data set. A strength of literature search data is that all the underlying literature sources
received data quality ratings of medium or higher. The primary limitation to this assessment is that
information on the conditions of use of asbestos at facilities in TRI & NEI is limited, and NRC does not
provide the condition of use of asbestos at facilities. Additional limitations include the uncertainty in the
mapping of reporting sites to the OES, as well as uncertainty in assumptions about the number of
operating days.
Some assumptions that were made in this release assessment include the assumption that the literature
data sufficiently represent all maintenance, renovation, and demolition activities, and that all releases
take place uniformly over time, as opposed to all at once or at varying intensities. Assessing
environmental releases using TRI, NEI, and NRC data presents various sources of uncertainty. TRI data
are self-reported and have reporting requirements that exclude certain facilities from reporting. Facilities
are only required to report to TRI if the facility has 10 or more full-time employees, is included in an
applicable NAICS code, and manufactures, processes, or uses the chemical in quantities greater than a
certain threshold (25,000 lb for manufacturers and processors and 10,000 lb for users). NEI reporting of
hazardous air pollutants, such as asbestos, is voluntary. Therefore, NEI may not include data from all
emission sources. In NRC data, spill quantities are often estimated or unknown. It is also possible that
not all spill incidents are reported to the NRC such that the available data likely does not encompass all
spill related releases of asbestos. An overall uncertainty in this assessment is that information on the
conditions of use of asbestos at facilities in TRI & NEI is limited, and NRC does not provide the
condition of use of asbestos at facilities.
E.10.4 Occupational Exposure Assessment
E.10.4.1 Worker Activities
During maintenance, renovation, and demolition activities, workers are potentially exposed during
various activities, including
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7612
7613
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7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
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• Inspecting buildings for asbestos-containing materials (ACM),
• Removing loose asbestos or ACM,
• Working in the vicinity of friable asbestos, and
• Handling demolition waste that may contain asbestos.
According to OSHA CFR 1910.1001, workers that handle asbestos are expected to wear proper
chemical-specific PPE. Workers typically wear coveralls, face shields, and respirators. Local exhaust
ventilation (LEV) and dust collection systems should be in place to control emissions, and LEV systems
should be installed on any tools that have potential to release asbestos fibers, such as saws, scorers, or
drills (OSHA. 2019). EPA did not find information that indicates the extent that engineering controls
and worker PPE are used at sites that may contain ACM in the United States.
When ACM is found in a commercial or public building, a contractor specialized in asbestos removal is
required to perform the removal. Regulation requires work practices that lower the emission potential
for asbestos, such as removing all asbestos-containing materials, adequately wetting all regulated
asbestos-containing materials, sealing the material in leak tight containers and disposing of the asbestos-
containing waste material as efficiently as possible (U.S. EPA. 1990b).
As stated in the process descriptions above, workers for this OES were separated into three SEGs:
Higher Exposure-Potential Workers, Lower Exposure-Potential Workers, and ONUs. Workers in these
similar exposure groups have different job functions and are therefore expected to have different levels
of potential exposure to friable asbestos. Because of this, their inhalation exposure risks are assessed
separately.
Higher exposure-potential workers are those that may directly generate friable asbestos through actions
such as grinding, sanding, cutting, or abrading ACM during maintenance or removal activities. Higher
exposure-potential workers include asbestos abatement contractors, maintenance workers, carpenters,
insulation workers, roofers, and floor/tile installers. Lower exposure-potential workers are not expected
to generate friable asbestos but may come into direct contact with friable asbestos while performing
their required work activities. Examples of lower exposure-potential workers are laborers, electricians,
plumbers, and masonry workers.
ONUs include employees that may be in the vicinity of asbestos but are unlikely to have direct contact
with ACM; ONUs are therefore expected to have lower inhalation exposures than other workers. ONUs
for this scenario include supervisors, managers, and other bystanders that may be in the area but do not
perform tasks that result in the same level of exposure as those workers that engage in tasks related to
removal or handling of asbestos.
E.10.4.2 Number of Workers and Occupational Non-users
To estimate the number of workers potentially exposed per establishment, EPA analyzed information
from BLS and 2019 data from the U.S. Census Bureau for the NAICS codes presented in Table Apx
E-19.
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TableApx E-19. Number of Employees and Establishments for Relevant NAICS Codes for
Maintenance, Renovation, and Demolition Activities
Industry
NAICS Description
Total
Firms
Total
Establishments
Total
Employees
Avg.
Employees
per Est.
236118
Residential Remodelers
114,459
114,874
387,534
3
236115
New Single-Family Housing
Construction (except For-Sale
Builders)
54,532
54,735
198,946
4
236220
Commercial and Institutional
Building Construction
38,130
39,368
623,672
16
237110
Water and Sewer Line and Related
Structures Construction
10,578
10,773
155,472
14
237120
Oil and Gas Pipeline and Related
Structures Construction
1,870
2,194
238,217
109
237130
Power and Communication Line and
Related Structures Construction
5,329
6,371
246,711
39
238130
Framing Contractors
11,954
11,976
86,120
7
238140
Masonry Contractors
18,391
18,507
143,032
8
238160
Roofing Contractors
20,945
21,197
192,877
9
238210
Electrical Contractors and Other
Wiring Installation Contractors
74,649
76,328
904,453
12
238220
Plumbing, Heating, and Air-
Conditioning Contractors
101,408
103,359
1,099,138
11
238310
Dry wall and Insulation Contractors
18,864
19,457
270,144
14
238330
Flooring Contractors
16,824
17,034
83,136
5
238350
Finish Carpentry Contractors
30,961
31,191
157,665
5
238910
Site Preparation Contractors
(Demolition)
37,102
37,491
407,175
11
238990
All Other Specialty Trade
Contractors
35,318
35,734
254,374
7
561720
Janitorial Services
58,011
62,592
1,096,144
18
561790
Other Services to Buildings and
Dwellings
14,689
14,841
74,894
5
562910
Remediation Services
4,120
5,044
86,224
17
7644
7645
7646
7647
7648
7649
7650
These data indicate that there are, on average, five workers and two ONUs per contractor establishment
within these NAICS codes, see Appendix E.5.2 for more information on this estimation process (U.S.
BLS. 2016). According to a 1984 survey conducted by EPA, about 20 percent of all buildings contain
asbestos (U.S. EPA. 1988a). Assuming 250 work days per year and a fraction of exposure to asbestos-
containing materials of 0.20, the exposure frequency for the OES is 50 days per year.
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7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
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TableApx E-20. Estimated Number of Workers Potentially Exposed to Asbestos During
Maintenance, Renovation, and E
•eniolition Activities
Number of
Establishments "
Exposed
Workers per
Establishment
Exposed
Occupational
Non-users per
Establishment
Total Exposed
Workers"
Total Exposed
Occupational
Non-users"
Total Exposed"
6.8E05
5
2
3.7E06
1.2E06
4.8E06
11 Totals have been rounded to two significant figures; totals may not add exactly due to rounding.
E.10.4.3 Occupational Exposure Results
When performing different activities involved in the maintenance, renovation, or demolition, workers
may come into contact with asbestos-containing construction materials that were manufactured or
imported into the U.S. and subsequently used in the construction of commercial and public buildings
(Paustenbach et al.. 2004). The information and data quality evaluation to assess occupational exposures
during maintenance, renovation, or demolition activities is listed in Table Apx E-4.
Occupational exposures to asbestos during maintenance, renovation, or demolition activities were
estimated by evaluating PBZ samples from OSHA's CEHD (OSHA. 2020) along with various literature
studies (see Table Apx E-4). The samples included 981 measurements reported as 8-hour TWAs and
151 measurements reported as short-term samples, split amongst the three SEGs using information
provided by NAICS and SIC codes associated with the data. A total of 200 of the 8-hour TWAs from the
OSHA CEHD were measured as non-detects for asbestos and 8-hour TWAs were calculated using the
asbestos LOD of 2,117.5 fibers/sample from NIOSH Method 7400. These data are shown in Asbestos
Part 2 Draft RE - Environmental Release and Occupational Exposure Data Tables - Fall 2023 (U.S.
EPA. 2023i).
EPA calculated the 95th percentile and 50th percentile of the available 981 TWA data points for
inhalation exposure monitoring data to assess the high-end and central tendency exposures, respectively.
Because the geometric standard deviation of the data set was greater than three for the worker inhalation
exposure samples, EPA used half the detection limit for the non-detect values in the central tendency
and high-end exposure calculations based on EPA's Guidelines for Statistical Analysis of Occupational
Exposure Data (U.S. EPA. 1994). Using these 8-hour TWA exposure concentrations, EPA calculated the
ADC for each SEG.
Only one sample was found to measure short-term inhalation exposure to ONUs. That sample was used
to make a high-end estimate and the central tendency was estimated at half of the high-end estimate.
These inhalation exposures are summarized for the three SEGs in Table Apx E-21, Table Apx E-22,
and Table Apx E-23 Additional information regarding the ADC calculation is provided in Appendix
E.5.4.1.
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7685
7686
7687
7688
7689
7690
7691
7692
7693
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TableApx E-21. Summary of Inhalation Monitoring Data for Maintenance, Renovation, and
Demolition Activities for Higher-Exposure Potential Workers
Exposure Concentration
Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number of
Samples
Data Quality
Rating of Air
Concentration Data
Weight of
Scientific
Evidence
8-hour TWA exposure
concentration
0.43
1.1E-03
847
High
Moderate
Chronic, non-cancer ADC"
2.0E-02
5.1E-05
30-minute short-term
exposure concentration
0.16
2.5E-02
145
High
Moderate
11 The Average Daily Concentration (ADC) presented here is based on 8-hour TWA monitoring data. Short-term
ADC estimates are calculated using the 30-minute exposure concentrations presented here, averaged with 7.5
hours at the full shift (i.e.. 8-hour TWA) exposure concentrations.
Table Apx E-22. Summary of Inhalation Monitoring Data for Maintenance, Renovation, and
Demolition Activities for Lower-Exposure Potentia
Workers
Exposure Concentration
Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number
of
Samples
Data Quality Rating
of Air
Concentration Data
Weight of
Scientific
Evidence
8-hour TWA exposure
concentration
0.22
1.1E-03
31
High
Moderate
Chronic, non-cancer ADC"
1.0E-02
5.1E-05
30-minute short-term
exposure concentration
2.5E-02
2.5E-02
5
High
Moderate
11 The Average Daily Concentration (ADC) presented here is based on 8-hour TWA monitoring data. Short-term
ADC estimates are calculated using the 30-minute exposure concentrations presented here, averaged with 7.5
hours at the full shift (i.e.. 8-hour TWA) exposure concentrations.
Table Apx E-23. Summary of Inhalation Monitoring Data for Maintenance, Renovation, and
Demolition Activities for O
NUs
Exposure Concentration
Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number
of
Samples
Data Quality Rating
of Air
Concentration Data
Weight of
Scientific
Evidence
8-hour TWA exposure
concentration
4.6E-02
1.2E-02
103
High
Moderate
Chronic, non-cancer ADC"
2.1E-03
5.6E-04
30-minute short-term
exposure concentration
5.3E-02
2.7E-02
1
High
Moderate
11 The Average Daily Concentration (ADC) presented here is based on 8-hour TWA monitoring data. Short-term
ADC estimates are calculated using the 30-minute exposure concentrations presented here, averaged with 7.5
hours at the full shift (i.e., 8-hour TWA) exposure concentrations.
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of this assessment is the use of a large number of directly applicable monitoring
data, which is preferrable to other assessment approaches such as modeling or the use of occupational
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7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
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7726
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exposure limits. However, the OSHA CEHD monitoring data does not include process information or
worker activities; therefore, there is uncertainty as to which worker activities these data cover and
whether all potential workers activities are represented in this data. Additionally, these data are from a
wide variety of facility types, and it is unclear how representative the data are for all sites and all
workers across the United States. Differences in work practices and engineering controls across sites can
introduce variability and limit the representativeness of any one site relative to all sites. Also, as
discussed above, EPA used half the detection limit for the non-detect values in the central tendency and
high-end exposure calculations. This introduces uncertainty into the assessment because the true value
of asbestos is unknown (though expected to be between zero and the level of detection).
E.ll Handling Asbestos-Containing Building Materials during Firefighting
or Other Disaster Response Activities
E.ll.l Process Description
As discussed above, various construction materials found in older buildings may contain asbestos.
Workers may come into contact with these materials in friable forms during firefighting and disaster
response operations at buildings with asbestos-containing material. Firefighting procedures depend on
the type and severity of the fire. The general procedure for firefighting involves entry and ventilation of
the burning structure, rescue of occupants, extinguishing of the fire and/or knockdown of the structure
(IARC. 2010). Disaster cleanup entails removing damaged structures and/or debris from the aftermath of
natural disasters (e.g., earthquakes, fires, floods) or unforeseen manmade disasters (e.g., explosions,
bombings). The general disaster cleanup process involves workers operating backhoes or front-end
loaders to remove debris and break it down into manageable chunks. This waste is loaded onto trucks
and transported to an approved landfill (Perkins et al.. 2007).
Building debris handled by disaster response crews may be a solid in the form of insulation, roofing,
tiles, and any other structural component of the destroyed building. Often, a primary source of asbestos
exposure comes from fibers in settled dust from the fire or disaster that is stirred up by disaster response
activities (Landrigan et al.. 2004). In one study, debris samples collected outside buildings and on cars
downwind from "ground zero" of the September 11, 2001, World Trade Center (WTC) attacks
contained 2.1 to 3.3 percent asbestos (Vitello. 2001). EPA did not find any chemical-specific
throughputs for the quantity of asbestos handled during disaster response activities.
Firefighting and disaster response activities do not have a consistent operating schedule, as they are
performed only as necessary. However, studies provide statistics on activity durations of firefighters.
One study cites that firefighter exposure duration to contaminants during cleanup of debris from the
WTC attacks lasted anywhere between 1 to 75 days per year (Szeinuk et al.. 2008). However, it should
be noted that the attack on the WTC is an unusual and extreme example of disaster-response activities.
Another study reported that firefighters work 10- to 24-hour shifts for 188 days per year (IARC. 2010).
E.11.2 Facility Estimates
CDR data was not available for this OES. The number of employment establishments is based on NFPA
reported data for the number of fire departments (NFPA. 2022b). The report shows 2,785 all-career;
2,459 mostly-career; 18,873 all-volunteer; and 5,335 mostly-volunteer fire/disaster response
departments. However, workers from one department may work at several fire/disaster sites each year,
and therefore the number of establishments for the OES is different than the number of sites where
exposures and releases occur.
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7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
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For determining the number of sites of exposures and releases, EPA used literature search data to
estimate the number of structural fires per year that contain asbestos. A report from the NFPA found that
489,600 structure fires happen each year (NFPA. 2022a). Therefore, to estimate the number of sites, this
figure was multiplied by 20 percent, per the ratio of buildings containing friable asbestos per a 1984
EPA survey (U.S. EPA. 1988a). The final estimate is 97,920 sites containing asbestos that undergo fire
or disaster each year.
E.11.3 Release Assessment
E.11.3.1 Environmental Release Points
EPA expects releases to occur during handling of asbestos-containing building materials during
firefighting or other disaster response activities. Release concerns arise from the disturbance of ACM
during disaster cleanup. Specific activities that may generate environmental releases include firefighting,
operating backhoes to remove debris, and loading debris onto trucks (Perkins et al.. 2007).
E.11.3.2 Environmental Release Assessment Results
For air, water, and land disposals, EPA assumed that the releases from an uncontrolled fire or other
asbestos clean up would be similar to the releases from demolition. Therefore, EPA estimated annual
releases using surrogate data from the literature search data, NRC, or TRI/NEI data for the maintenance,
renovation, and demolition OES. Then, EPA estimated daily releases by dividing the annual releases by
the number of operating days determined for this OES, which is different than that of the previous OES,
resulting in different daily land disposal estimates.
A summary of daily environmental release estimates by media for this OES are provided in Table 3-8. In
addition, TableApx E-24, TableApx E-25, and TableApx E-26 below present a summary of annual
and daily releases estimates to water, air, and land, respectively. For the raw data set used in making
these estimations, see Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure
Data Tables - Fall 2023 (U.S. EPA. 2023iY
Table Apx E-24. Wastewater Discharge Summary for Handling Asbestos-Containing Building
Materials During Firefighting or Other Disaster Response Activities
Annual Wastewater Discharges
(kg/site-year)
Number of
Daily Wastewater Discharges (kg/site-day)
Central Tendency
High-End
Operating Days
Central Tendency
High-End
1.4
45
1
1.4
45
Table Apx E-25. Air Emission Summary for Handling Asbestos-Containing Building Materials
Annual Fugitive
Annual Stack
Daily Fugitive
Daily Stack
Emissions
Emissions
Number of
Emissions
Emissions
(kg/site-year)
(kg/site-year)
Operating
(kg/site-day)
(kg/site-day)
Central
High-
Central
High-
Days
Central
High-
Central
High-
Tendency
End
Tendency
End
Tendency
End
Tendency
End
9.1E-03
1.8
N/A
N/A
1
9.1E-03
1.8
N/A
N/A
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7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
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TableApx E-26. Land Release Summary for Handling Asbestos-Containing Building Materials
During Firefighting or Other Disaster Response Activities
Annual Land Disposals (kg/site-
year)
Number of
Operating Days
Daily Land Disposals (kg/site-day)
Central Tendency
High-End
Central Tendency
High-End
4,935
9,764
1
4,935
9,764
Strengths, Limitations, Assumptions, and Uncertainties
Even though surrogate data was used, a strength of this assessment is that the surrogate sources fall
under monitoring/measured data, which is most preferred based on the hierarchy of approaches. A
limitation of this assessment includes the lack of OES-specific data. EPA assumed that the releases from
the surrogate OES are representative of this OES. In addition to having the same strengths, limitations,
assumptions, and uncertainties as the surrogate OES, the use of surrogate data may introduce
uncertainties related to the extent to which the surrogate OES and the OES being assessed are similar.
E.11.4 Occupational Exposure Assessment
E.11.4.1 Worker Activities
During firefighting or other disaster-response activities, workers are potentially exposed while
performing the following activities:
• Responding to fires in buildings for asbestos-containing materials (ACM),
• Removing loose asbestos or ACM,
• Working in the vicinity of friable asbestos, and
• Handling building waste that may contain asbestos.
Worker activities for this occupational exposure scenario are based on firefighting activities, as disaster
response activities are expected to be similar to those for firefighting. The general procedure for
firefighting involves entry and ventilation of the burning structure, rescue of occupants, extinguishing of
the fire and/or knockdown of the structure (IARC. 2010). Firefighters may be exposed to asbestos by
performing any of these activities when responding to fires in buildings that contain asbestos.
There are two general phases in municipal structural firefighting: knockdown and overhaul. During
knockdown, firefighters control and extinguish the fire. Municipal structural fires are either extinguished
within 5 to 10 minutes, or abandoned and fought from the outside. During overhaul, any remaining
small fires are extinguished (IARC. 2010). When responding to an active fire, firefighters employ a
personal protective ensemble that covers the entire body with a self-contained breathing apparatus
(SCBA) system providing breathable air; however, they do not always wear SCBA during exterior
operations (deploying hoses, forcible entry) or during overhaul operations (Fent et al.. 2015).
E.11.4.2 Number of Workers and Occupational Non-users
Due to limited information found in the BLS data, the number of workers and establishments for
firefighting and other disaster response activities were estimated using data from the National Fire
Protection Association (NFPA) (NFPA. 2022b). The survey provides an estimate for the number of
career firefighters at 364,300 and volunteer firefighters at 676,900.
The NFPA survey also indicates that departments with "All Volunteer" and "Mostly Volunteer" (24,208
departments total) handle firefighting for 30 percent of the population and that departments with
"Mostly Career" and "All Career" (5,244 departments total) handle firefighting for 70 percent of the
population. Based on this, EPA assumes that career firefighters handle 70 percent of structure fires and
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7824
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7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
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7839
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PUBLIC RELEASE DRAFT
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volunteer firefighters handle 30 percent of structure fires. This equates to an estimate of 69 career
firefighters and 28 volunteer firefighters per department.
EPA generally assumes career and volunteer firefighters have relatively equal exposure potential. EPA
also assumes that firefighters work 250 days/year; however, a firefighter would not be exposed to
asbestos every workday. Instead, each firefighter responds to a certain number of structure fires each
year, each with an estimated 20 percent chance of containing asbestos. NFPA estimates that there are 10
-16 firefighters/structure fire for suburban and urban areas and 4 to 6 firefighters/structure fire for
smaller areas (NFPA. 2012). EPA assumes that career firefighters are stationed in higher density areas
and volunteer firefighters cover lower density areas, therefore, career firefighters respond in teams of 10
-16 and volunteers may respond in teams of 4 to 6. EPA assumes that all workers engaged in
firefighting and disaster response activities are potentially subject to high levels of exposure; therefore,
ONUs are not considered as a worker category for this OES.
TableApx E-27. Estimated Number of Workers Potentially Exposed to Asbestos During
Firefighting or <
Dther Disaster Response Activities
Number of
Departments"
Exposed Career
Firefighters per
Department
Exposed
Volunteer
Firefighters per
Department
Total Exposed
Career
Firefighters"
Total Exposed
Volunteer
Firefighters"
Total
Exposed"
2.4E04
N/A
28
N/A
6.8E05
1.0E06
5.2E03
69
N/A
3.6E05
N/A
" Totals have been rounded to two significant figures. Totals may not add exactly due to rounding.
E.11.4.3 Occupational Exposure Result
Firefighters and other disaster responders may come into contact with asbestos-containing construction
materials that were used in the construction of commercial and public buildings when responding to
fires at these buildings. The information and data quality evaluation to assess occupational exposures
during firefighting and other disaster response activities is listed in Table Apx E-4.
Occupational exposures to asbestos during firefighting and other disaster response activities were
estimated by evaluating PBZ samples from four literature studies (see Table Apx E-4). One source
gathered 636 phase contrast microscopy (PCM) and 114 transmission electron microscopy (TEM) air
samples for disaster workers responding to the World Trade Center on September 11, 2001; however,
the source only provided the minimum and maximum asbestos concentrations from the two groups of
samples. EPA therefore assessed the minimum and maximum for the PCM samples and the maximum
for the TEM samples; the minimum TEM sample was omitted because it was below the LOD but the
source did not provide the LOD for the sampling method (Wallingford and Snyder. 2001).
Two sources collected a total of 62 PBZ inhalation exposure samples during debris cleanup after fires
(Beaucham and Eisenberg. 2019; Lewis and Curtis. 1990). Another source provided two ranges of
sampling data that covered 33 PCM data points and three ranges of sampling that covered 45 TEM data
points, each of these ranges covered a 6- to 10-day sampling period (Brevsse et al.. 2005). Because the
discrete samples were not provided in the study, EPA used the minimums and maximums from each
range in the assessment. Of the 62 PBZ samples collected from these four sources, three were non-detect
and an LOD was used to estimate the asbestos concentration of the sample. The authors of the data
studies provided the LOD for two of the points, while the non-detect from Wallingford & Snyder was
calculated by EPA assuming that NIOSH 7400 was used to analyze PCM samples (Wallingford and
Snyder. 2001).
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To calculate the number of fires responded to by each worker per year and therefore, the number of
potential exposure days per year, EPA considers all career firefighters (364,300 career firefighters) in
teams of 10 responding to 70 percent of all annual structure fires (342,720 fires), which equates to
approximately 10 fires/team/year. Assuming teams of 16, that would be approximately 15
fires/team/year. EPA estimates that career firefighters experience 10 to 15 structure fires/worker/year.
Only 20 percent of those occurrences would be expected to contain ACM, so 2 to 3 ACM structure
fires/worker/year. Estimating all volunteer firefighters (676,900 volunteers) working in teams of 4 to 6
and responding to 30 percent of all annual structure fires (146,880 fires) equates to 1 to 2 structure
fires/volunteer/year, with only 20 percent being ACM-related. Therefore, EPA assumes a high-end
estimate of 1 ACM structure fire/volunteer/year.
EPA calculated the 95th percentile and 50th percentile of the available 62 data points for inhalation
exposure monitoring data to assess the high-end and central tendency exposures, respectively. Using
these 8-hour TWA exposure concentrations, EPA calculated the ADC. Inhalation exposure estimates are
summarized in TableApx E-28 and TableApx E-29 Additional information regarding the ADC
calculation is provided in Appendix E.5.4.
Table Apx E-28. Summary of Inhalation Monitoring Data for Firefighting and Other Disaster
Response Activities for Career Firefighters
Exposure Concentration Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number
of
Samples
Data Quality Rating
of Air Concentration
Data
Weight of
Scientific
Evidence
8-hour TWA Exposure Concentration
0.39
2.0E-02
62
High
Moderate to
Robust
Chronic, Non-cancer ADC'1
1.1E-03
5.5E-05
30-min Short-Term Exposure
Concentration
-
-
a The average daily concentration (ADC) presented here is based on 8-hour TWA monitoring data. Short-term exposure
data were not available for this scenario.
Table Apx E-29. Summary of Inhalation Monitoring Data for Firefighting and Other Disaster
Response Activities for Volunteer Firefighters
Exposure Concentration Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number
of
Samples
Data Quality Rating
of Air Concentration
Data
Weight of
Scientific
Evidence
8-hour TWA Exposure Concentration
0.39
2.0E-02
62
High
Moderate to
Robust
Chronic, Non-cancer ADCa
3.5E-04
1.8E-05
30-min Short-Term Exposure
Concentration
-
-
11 The average daily concentration (ADC) presented here is based on 8-hour TWA monitoring data. Short-term exposure
data were not available for this scenario.
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of the data used for this assessment is the use of directly applicable monitoring
data, which is preferrable to other assessment approaches such as modeling or the use of occupational
exposure limits. An additional strength is that the literature sources include information on worker
activities. The data from these four studies only cover a narrow selection of building/structure fires, and
it is unclear how representative the data are for all disaster response sites and all disaster response
workers across the United States. Differences in work practices and engineering controls across sites can
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7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
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7906
7907
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PUBLIC RELEASE DRAFT
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introduce variability and limit the representativeness of any one site relative to all sites. Two of the
sources only provided ranges for their data sets, potentially reducing the usefulness of the data and the
accuracy of the exposure estimates. There is also uncertainty in EPA's assumption of exposure
frequency and exposure duration.
E.12 Use, Repair, or Removal of Industrial and Commercial Appliances or
Machinery Containing Asbestos
E.12.1 Process Description
Various industrial and commercial appliances and machinery may contain asbestos. The asbestos may
be present in gaskets, reinforced plastics, industrial brake and gear clutches, and packing seals within
machinery. Workers may come into contact with these materials in friable forms during use, repair, or
removal of the appliances and machinery containing asbestos. In general, repair of appliances containing
asbestos consists of disassembly of the machinery, replacement and/or repair of individual parts, and
reassembly of the machinery. Often, asbestos-containing components of the machinery are replaced with
components that do not contain asbestos, and the asbestos waste or debris is disposed of (Mlynarek and
Van Orden. 2012). Friable ACM must be disposed of in leak tight containers (e.g., 6 mil polyethylene
bags). Bags can be placed in 55-gallon drums for additional protection (Banks. 1991).
Brake linings and gaskets are some of the most common machinery parts that contain asbestos. During
brake repair and removal, the brakes are disassembled by removing the brake housing using a manual or
power wrench to loosen bolts holding the housing in place. Then, the entire brake apparatus is removed
from the machinery. Compressed air is used to clear the brake of any dusts and debris which may
contain asbestos. Last, the brake linings are removed from the brakes (Madl et al.. 2009). During gasket
and valve repair and removal, mechanics remove gaskets with a scraper and use a brush to clean
remaining residue from the surface (Liukonen and Weir. 2005). Installed gaskets typically remain in
operation anywhere from a few weeks to 3 years; the timeframe before being replaced is largely
dependent upon the temperature and pressure conditions (ACC. 2017). whether due to detected leaks or
as part of a routine maintenance campaign. Used asbestos containing gaskets are handled as regulated
non-hazardous material and are immediately bagged after removal from process equipment and then
placed in containers designated for asbestos containing waste.
Asbestos-containing materials in industrial or commercial appliances and machinery may be in solid
form, sometimes in blocks or sheets (Scarlett et al.. 2012; Mancuso. 1991). Table Apx E-30 provides
common asbestos-containing materials to which workers may be exposed, along with the associated
asbestos concentrations of the ACM. EPA did not find any chemical-specific volumes for asbestos
handled during the use, repair, or disposal of industrial and commercial appliances or machinery
containing asbestos
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7923
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7925
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7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
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PUBLIC RELEASE DRAFT
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TableApx E-30. Legacy Asbestos Concentrations for Common Appliance and Machinery
Components
Product Category
Percentage
Form of
Asbestos
Source
Friction Materials
15-70
C
(IPCS. 1986)
Molded Plastics and Battery Boxes
55-70
C and Cr
(IPCS. 1986)
Jointings and Packings
25-85
C and Cr
(IPCS. 1986)
Fillers
25-98
C and Cr
(IPCS. 1986)
Lagging
9-96
C and A
(Scansetti et al..
1993)
Machinery Insulation
15-60
C and A
(Standard Oil, 1981)
C = Chrysotile, A = Amosite, Cr = Crocidolite
EPA did not identify data on site operating schedules; therefore, EPA assumes 250 days/yr of operation.
However, sources report that the lifespan of furnace linings and other asbestos-containing machinery
linings can range from approximately 400 to 600 heats. In addition, the length of time that a furnace
operates once it is fully heated is typically 6 to 7 years, and up to 10 years, after which time the furnace
is shut down and is relined (Hollins et al.. 2019). It is assumed that industrial workers would be
primarily exposed to the asbestos while replacing the lining once every 6-10 years. Exposure
frequencies for workers may be higher for other types of appliances or machinery.
E.12.2 Facility Estimates
CDR data were not available for this OES. Therefore, EPA used BLS and SUSB data to estimate the
number of establishments. Because it is assumed that employees work only at the employment
establishment, the number of establishments is considered equal to the number of sites for this OES.
EPA assumed that establishments involved in the use, repair, or removal of industrial or commercial
appliances or machinery containing asbestos are classified under the applicable NAICS codes 324110
(Petroleum Refineries), 325199 (All Other Basic Organic Chemical Manufacturing), and 423830
(Industrial Machinery and Equipment Merchant Wholesalers). Based on the 2021 County Business
Patterns data published by the U.S. Census Bureau, there are 29,211 establishments classified under
these NAICS codes. This provides a high-end bounding estimate for the number of sites for this OES.
E.12.3 Release Assessment
E.12.3.1 Environmental Release Points
EPA expects releases to occur during the use, repair, or removal of industrial and commercial appliances
or machinery containing asbestos. As stated in the process description, asbestos may be present in
gaskets, reinforced plastics, industrial brake and gear clutches, and packing seals. Specific activities that
may generate environmental releases include disassembly of machinery, replacement and/or repair of
individual parts, and reassembly of machinery.
E.12.3.2 Environmental Release Assessment Results
EPA estimated releases from this OES using TRI and NEI data, as described in Appendix E.4. TRI data
were available for water, air, and land disposals, NEI data were available for air emissions. EPA
estimated daily emissions for this OES by calculating the 50th and 95th percentile of all reported annual
releases and dividing the results by 250 release days/yr determined in Appendix E.4.4.
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7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
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PUBLIC RELEASE DRAFT
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Based on the available data, EPA expects asbestos releases to air (fugitive and stack) and landfills.
However, EPA does not expect wastewater discharges, as there were no reported wastewater discharges
in the 2016-2020 TRI data associated with this OES. There may be incidental discharges of asbestos,
however EPA expects those releases to be low and occur infrequently.
A summary of daily environmental release estimates by media for this OES are provided in Table 3-8. In
addition, TableApx E-31 and TableApx E-32 below present a summary of annual and daily releases
estimates to air and land, respectively. For the raw data set used in making these estimations, see
Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure Data Tables - Fall 2023
(U.S. EPA. 2023iY
Table Apx E-31. Air Emission Summary for Use, Repair, or Removal of Industrial and
Commercial Appliances or Machinery
Annual Fugitive
Emissions (kg/site-
year)
Annual Stack
Emissions (kg/site-
year)
Number of
Operating
Days
Daily Fugitive
Emissions (kg/site-
day)
Daily Stack
Emissions (kg/site-
day)
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
2.3E-02
23
0
1.6E-
02
250
9.1E-05
9.0E-
02
0
6.6E-
05
Table Apx E-32. Land Release Summary for Use, Repair, or Removal of Industrial and
Commercial Appliances or Machinery
Annual Land Disposals" (kg/site-
year)
Number of
Operating Days
Daily Land Disposals (kg/site-day)
Central Tendency
High-End
Central Tendency
High-End
16,804
156,703
250
67
627
a Total land disposals include the following land disposal methods: RCRA Subtitle C Landfills, Other on-site
landfills, Other off-site landfills, Other land disposal, and Other off-site management
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of these estimates is that EPA used multiple years of data in the analysis. A
strength of TRI data is that TRI compiles the best readily available release data for all reporting
facilities. A strength of NEI data is that it includes comprehensive and detailed estimates of air
emissions from point and area sources. The primary limitation to this assessment is that information on
the conditions of use of asbestos at facilities in TRI and NEI is limited. Additional limitations to this
assessment include the assumptions on the number of operating days to estimate daily releases, the
assumption of no wastewater discharges (as reported in TRI), and the uncertainty in the mapping of
reporting facilities to this OES.
For purposes of release assessment, it is assumed that the included data sufficiently represent all OES
activities and that all releases take place uniformly over time, as opposed to all at once or at varying
intensities. Another assumption is that the distribution created from the reporting sites is representative
of all non-reporting sites. Assessing environmental releases using TRI and NEI data presents various
sources of uncertainty. TRI data are self-reported and have reporting requirements that exclude certain
facilities from reporting. Facilities are only required to report to TRI if the facility has 10 or more full-
time employees, is included in an applicable NAICS code, and manufactures, processes, or uses the
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7991
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7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
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PUBLIC RELEASE DRAFT
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chemical in quantities greater than a certain threshold (25,000 lb for manufacturers and processors and
10,000 lb for users). NEI reporting of hazardous air pollutants, such as asbestos, is voluntary. Therefore,
NEI may not include data from all emission sources. There is uncertainty in EPA's assumption of no
wastewater discharges for this OES, as there could be more sites that dispose of/treat asbestos waste that
are below the TRI reporting thresholds.
E.12.4 Occupational Exposure Assessment
E.12.4.1 Worker Activities
As stated above, various industrial and commercial appliances and machinery may contain asbestos. The
asbestos may be present in gaskets, reinforced plastics, industrial brake and gear clutches, and packing
seals within machinery. Workers may come into contact with these asbestos in friable forms during use,
repair, or removal of the appliances and machinery that contain asbestos. In general, repair of appliances
containing asbestos consists of disassembly of the machinery, replacement and/or repair of individual
parts, and reassembly of the machinery. Often, asbestos-containing components of the machinery are
replaced with components that do not contain asbestos, and the asbestos waste or debris is disposed of
(Mlynarek and Van Orden. 2012). Friable ACM must be disposed of in leak tight containers (e.g., 6 mil
polyethylene bags). Bags can be placed in 55-gallon drums for additional protection (Banks. 1991).
EPA did not find information that indicates the extent that engineering controls and worker PPE are used
at sites that work on industrial or commercial equipment or machinery that contain asbestos in the
United States.
ONUs include employees that work at the site where industrial or commercial equipment or machinery
that contain asbestos are repaired or removed, but they do not directly handle the chemical or work with
the machinery and are therefore expected to have lower inhalation exposures than workers. ONUs
include supervisors, managers, and other employees that may be in the work area but do not perform
tasks that result in the same level of exposures as workers that engage in tasks related to the OES.
E.12.4.2 Number of Workers and Occupational Non-users
EPA used workers and ONU estimates determined from an analysis of BLS data for the NAICS codes
324110, Petroleum Refineries; 325199, All Other Basic Organic Chemical Manufacturing; and 423830,
Industrial Machinery and Equipment Merchant Wholesalers. EPA assumes that all workers at these sites
could potentially be exposed to ACM (U.S. BLS. 2016). Data from the 2019 U.S. Census Bureau
estimated a total of 29,211 establishments that operated under these NAICS codes. Based on these data,
EPA estimated that a total of two workers and two ONUs are potentially exposed per establishment in
this exposure scenario.
Table Apx E-33. Estimated Number of Workers Potentially Exposed to Asbestos During Use,
Repair, or Removal of Industrial and Commercial Appliances or IV
achinery
Number of
Establishments"
Exposed
Workers per
Establishment
Exposed ONUs
per
Establishment
Total
Exposed
Workers"
Total ONUs"
Total
Exposed"
2.9E04
2
2
6.4E04
5.5E04
1.2E05
11 Totals have been rounded to two significant figures. Totals may not add exactly due to rounding.
E.12.4.3 Occupational Exposure Result
Asbestos may be present in gaskets, reinforced plastics, industrial brake and gear clutches, and packing
seals within machinery used in industrial or commercial workplaces. Workers may come into contact
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8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
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with these materials in friable forms during use, repair, or removal of the appliances and machinery
containing asbestos. The information and data quality evaluation to assess occupational exposures
during use, repair, or removal of industrial or commercial appliances or machinery is listed in
TableApx E-4.
Occupational exposures to asbestos during use, repair, or removal of the appliances and machinery were
estimated by evaluating PBZ samples from OSHA's CEHD monitoring data (OSHA. 2020) along with
two NIOSH Health Hazard Evaluations (HHE's) and other literature studies (see Table Apx E-4). The
samples used for this assessment include 236 data points, reported as 8-hour TWAs, and a total of 37
short-term samples that were each taken over 30 minutes. Nine of the TWA data points were non-detect
for asbestos and 8-hour TWAs were calculated using the asbestos LOD of 2117.5 fibers/sample
(https://www.cdc.gOv/niosh/docs/2003-154/pdfs/7400.pdf). These data are shown in Asbestos Part 2
Draft RE - Environmental Release and Occupational Exposure Data Tables - Fall 2023 (U.S. EPA.
2023i).
EPA calculated the 95th percentile and 50th percentile of the available TWA and short-term data points
for inhalation exposure monitoring data to assess the high-end and central tendency exposures,
respectively. Because the geometric standard deviation of the data set was greater than three for the
worker inhalation exposure samples, EPA used half the detection limit for the non-detect values in the
central tendency and high-end exposure calculations based on EPA's Guidelines for Statistical Analysis
of Occupational Exposure Data (U.S. EPA. 1994).
The exposure frequency for this exposure scenario is estimated at 250 days/year based on a worker
schedule of 5 days per week and 50 weeks per year. EPA estimated worker exposure over the full
working day, or 8 hours/day, as the data used to estimate inhalation exposures are 8-hour TWA data.
Short-term exposure data for ONUs were not available as all OSHA data were assumed to be applicable
for workers. The ONU exposures are anticipated to be lower than worker exposures because ONUs do
not typically directly handle the chemical. These inhalation exposures are summarized for workers and
ONUs in Table Apx E-34 and Table Apx E-35. Additional information regarding the ADC calculation
is provided in Appendix E.5.4.
Table Apx E-34. Summary of Inhalation Monitoring Data for Use, Repair, or Removal of
Appliances or Machinery for Workers
Exposure Concentration
Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number
of
Samples
Data Quality
Rating of Air
Concentration Data
Weight of
Scientific
Evidence
8-hour TWA Exposure
Concentration
0.16
8.4E-03
216
High
Moderate to
Robust
Chronic, non-cancer ADC"
3.6E-02
1.9E-03
30-min Short-Term
Exposure Concentration
0.17
1.9E-02
37
High
Moderate to
Robust
11 The ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated
using the 30-minute exposure concentrations presented here, averaged with 7.5 hours at the full shift (i.e.. 8-hour
TWA) exposure concentrations.
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8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
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TableApx E-35. Summary of Inhalation Monitoring Data for Use, Repair, or Removal of
Appliances or Machinery for ONUs
Exposure Concentration
Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number of
Samples
Data Quality
Rating of Air
Concentration Data
Weight of
Scientific
Evidence
8-Hour TWA Exposure
Concentration
4.9E-02
2.8E-02
20
High
Moderate
to Robust
Chronic, Non-cancer ADC"
1.1E-02
6.4E-03
30-Minute Short-Term
Exposure Concentration
-
-
11 The ADC presented here is based on 8-hour TWA monitoring data. Short-term exposure data were not available
for ONUs for this scenario.
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of the data used for this assessment is the use of directly applicable monitoring
data, which is preferrable to other assessment approaches such as modeling or the use of occupational
exposure limits. An additional strength is that the literature sources include information on worker
activities. The OSHA CEHD monitoring data does not include process information or worker activities;
therefore, there is uncertainty as to which worker activities these data cover and whether all potential
workers activities are represented in this data. Additionally, these data are from a wide variety of facility
types, and it is unclear how representative the data are for all sites and all workers across the United
States. Differences in work practices and engineering controls across sites can introduce variability and
limit the representativeness of any one site relative to all sites. As discussed above, EPA used half the
detection limit for the non-detect values in the central tendency and high-end exposure calculations. This
introduces uncertainty into the assessment because the true value of asbestos is unknown (though
expected to be between zero and the level of detection).
E.13 Handling Articles or Formulations that Contain Asbestos
E.13.1 Process Description
Asbestos may be contained in articles or formulations such as plastics, joints and packings, and fillers
(including talc containing asbestos fillers) that were manufactured before the 1980s. In general, asbestos
contained in these objects is less likely to become friable since the asbestos is entrained in the articles
and is not likely to be released; however, it is possible release may occur during rough handling of the
objects (Perkins et aL 2007). See Table Apx E-36 below for asbestos concentration forms and ranges
for these articles and formulations.
Table Apx E-36. Asbestos Concentrations for Common Articles and Formulations
Product Category
Percentage
Form of Asbestos
Source
Moulded Plastics and Battery Boxes
55-70
Chrysotile and crocidolite
(IPCS. 1986)
Joints and Packings
25-85
Chrysotile and crocidolite
(IPCS. 1986)
Fillers
25-98
Chrysotile and crocidolite
(IPCS. 1986)
There often are large quantities of GWB in buildings, and in buildings built before the 1980s, the joint
compound may contain asbestos. Because the two materials are bonded together, the GWB and its
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associated ACM joint compound are considered one material by EPA. In contrast, because OSHA
requires sampling of the GWB and joint compound separately, OSHA typically considers the joint
compound to be ACM (Perkins et al.. 2007). Before removal, the joint compound and GWB are
thoroughly wetted to avoid dust formation (Perkins et al.. 2007).
E.13.2 Facility Estimates
CDR data were not available for this OES. Therefore, EPA used BLS and SUSB data to estimate the
number of establishments. Because it is assumed that employees work only at the employment location,
the number of establishments is considered equal to the number of sites for this OES. EPA assumes that
establishments involved in handling articles or formulations that contain asbestos are classified under
the applicable NAICS codes 336411 (Aircraft Manufacturing), 541715 (Research and Development in
the Physical, Engineering, and Life Sciences [except Nanotechnology and Biotechnology]), and 611310
(Colleges, Universities, and Professional Schools). Based on the 2021 County Business Patterns data
published by the U.S. Census Bureau, there are 15,592 establishments classified under these NAICS
codes. This provides a high-end bounding estimate for the number of sites for this OES.
E.13.3 Release Assessment
E.13.3.1 Environmental Release Points
EPA expects releases to occur during the handling of articles or formulations that contain asbestos. As
stated in the process description, asbestos may be present in plastics, joints and packings, and fillers
(including talc containing asbestos fillers) that were manufactured before the 1980s. Specific activities
that may generate environmental releases include rough handling of these articles or during work or
removal of gypsum wallboards.
E.13.3.2 Environmental Release Assessment Results
EPA estimated releases from this OES using TRI and NEI data, as described in Appendix E.4. TRI data
were available for water, air, and land disposals, while NEI data were available for air emissions. In
summary, EPA estimated daily emissions for this OES by calculating the 50th and 95th percentile of all
reported annual releases and dividing the results by 250 release days/year as determined in Appendix
E.4.4.
Based on the available data, EPA expects asbestos releases to air (fugitive and stack) and landfills.
However, EPA does not expect wastewater discharges of asbestos during this OES, because the data
gathered shows no discharges of asbestos to water. Each OES contained reporting sites from TRI from
other medias of release, but not to water. Therefore, EPA assumed that there are no wastewater
discharges of asbestos from this OES. Although there may be incidental discharges of asbestos, EPA
expects those releases to be low.
EPA estimated air emissions using 10 reporting sites from TRI/NEI. EPA then built a distribution using
central tendency and high-end results from the 10 data points to estimate releases from all potential sites
under this OES. To estimate land releases, a similar approach was taken using a distribution built from
the 4 reporting sites (11 data points) to estimate releases from all potential sites. The annual release
values are the high end and central tendency values from each site's releases, separated by the type of
land release and by waste-receiving facility.
A summary of daily environmental release estimates by media for this OES are provided in Table 3-8. In
addition, TableApx E-37 and TableApx E-38 below present a summary of annual and daily releases
estimates to air and land, respectively. For the raw data set used in making these estimations, see
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Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure Data Tables - Fall 2023
(U.S. EPA. 20230.
TableApx E-37. Air Emission Summary for Handling Articles or Formulations that Contain
Asbestos
Annual Fugitive
Emissions
(kg/site-year)
Annual Stack
Emissions
(kg/site-year)
Number of
Operating
Days
Daily Fugitive
Emissions
(kg/site-day)
Daily Stack
Emissions
(kg/site-day)
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
6.8E-02
88
2.1
3.4
250
2.7E-04
0.35
8.5E-03
1.4E-02
Table Apx E-38. Land Release Summary for Handling Articles or Formulations that Contain
Asbestos
Annual Land Disposals"
(kg/site-year)
Number of
Operating
Days
Daily Land Disposals
(kg/site-day)
Central
Tendency
High-End
Central
Tendency
High-End
14,057
58,323
250
56
233
"Total land disposals include the following land disposal methods: other landfills and transfer to
waste broker.
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of these estimates is that EPA used multiple years of data in the analysis. A
strength of TRI data is that it compiles the best readily available release data for all reporting facilities.
A strength of NEI data is that it includes comprehensive and detailed estimates of air emissions from
point and area sources. The primary limitation to this assessment is that information on the COUs of use
of asbestos at facilities in TRI and NEI is limited. Additional limitations to this assessment include the
assumptions on the number of operating days to estimate daily releases, the assumption of no
wastewater discharges (as reported in TRI), and the uncertainty in the mapping of reporting facilities to
this OES.
For purposes of release assessment, EPA assumed that (1) the included data sufficiently represent all
OES activities; and (2) all releases take place uniformly over time, as opposed to all at once or at
varying intensities. Assessing environmental releases using TRI and NEI data presents various sources
of uncertainty. TRI data are self-reported and have reporting requirements that exclude certain facilities
from reporting. Facilities are only required to report to TRI if the facility has 10 or more full-time
employees, is included in an applicable NAICS code, and manufactures, processes, or uses the chemical
in quantities greater than a certain threshold (25,000 lb for manufacturers and processors and 10,000 lb
for users). NEI reporting of hazardous air pollutants, such as asbestos, is voluntary. Therefore, NEI may
not include data from all emission sources. There is uncertainty in EPA's assumption of no wastewater
discharges for this OES, as there could be more sites that dispose of/treat asbestos waste that are below
the TRI reporting thresholds.
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E.13.4 Occupational Exposure Assessment
E.13.4.1 Worker Activities
Asbestos may be contained in articles or formulations such as plastics, joints and packings, and fillers
(including talc containing asbestos fillers) that were manufactured before the 1980s. Also, asbestos is
used as a component in some specialty plastics used in missile research and development. In general,
asbestos contained in these objects is less likely to become friable since the asbestos is entrained in the
articles and is not likely to be released; however, it is possible that release can occur during rough
handling of the objects (Perkins et al.. 2007). Asbestos may also be present in GWB joint compounds in
buildings that were constructed before the phase-out of ACM. Joint compound applied in the past may
become friable when the wallboard is worked on or removed.
Two sites were identified that reported land releases of asbestos to TRI; one reported to NAICS code
927110, Space Research and Technology, while the other reported to NAICS code 541715, Research
and Development in the Physical, Engineering, and Life Sciences (except Nanotechnology and
Biotechnology) (U.S. EPA. 2022a). Three sites reported asbestos air emissions to TRI under the NAICS
code 611310, Colleges, Universities, and Professional Schools (U.S. EPA. 2022a). EPA expects that
asbestos is used for research at these sites under controlled conditions and exposure potential to friable
asbestos is minimized.
Similar to the OES for maintenance, renovation, and demolition activities, workers for this OES were
separated into three SEGs: high exposure-potential workers, low exposure-potential workers, and ONUs.
Workers in these SEGs have different job functions and are therefore expected to have different levels of
potential exposure to friable asbestos. For this reason, their inhalation exposure risks are assessed
separately.
Higher exposure-potential workers are workers that may directly generate friable asbestos through
actions such as grinding, sanding, cutting, or abrading ACM during maintenance or removal. Lower
exposure-potential workers are not expected to generate friable asbestos but may come into direct
contact with friable asbestos while performing their required work activities. ONUs include employees
that may be in the vicinity of asbestos but are unlikely to have direct contact with ACM, and are
expected to have lower inhalation exposures than other workers. ONUs for this scenario include
supervisors, managers, and other bystanders who may be in the area but do not perform tasks that result
in the same level of exposure as those workers who engage in tasks related to ACM removal or handling
of asbestos.
E.13.4.2 Number of Workers and Occupational Non-users
EPA used workers and ONU estimates determined from an analysis of BLS data for the NAICS codes
336411, Aircraft Manufacturing; 611310, Colleges, Universities, and Professional Schools; and 541715,
Research and Development in the Physical, Engineering, and Life Sciences (except Nanotechnology and
Biotechnology). EPA assumes that all workers at these sites could potentially be exposed to ACM (U.S.
BLS. 2016). Data from the 2019 U.S. Census Bureau estimated a total of 15,592 establishments that
operated under these NAICS codes. Based on these data, EPA estimated that a total of 20 workers and
11 ONUs are potentially exposed per establishment in this exposure scenario.
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TableApx E-39. Estimated Number of Workers Potentially Exposed During Handling Articles or
Formulations that Contain Asbestos
Number of
Establishments
Exposed
Workers per Site
Establishment
Exposed ONUs per
Establishment
Total Exposed
Workers"
Total
ONUs"
Total
Exposed"
1.6E04
20
11
3.1E05
1.6E05
4.7E05
11 Totals have been rounded to two significant figures. Totals may not add exactly due to rounding.
E.13.4.3 Occupational Exposure Result
Workers may come into contact with friable asbestos while handling articles or formulations such as
plastics, joints and packings, and fillers (including talc containing asbestos fillers) that contain asbestos.
The information and data quality evaluation to assess occupational exposures for workers while
handling asbestos-containing articles or formulations is listed in Table Apx E-4.
Occupational exposures to asbestos from handling articles or formulations were estimated by evaluating
PBZ samples from OSHA's CEHD monitoring data (OSHA. 2020) along with three studies found
during the data extraction and evaluation stage of the risk evaluation (see Table Apx E-4). For the three
SEGs assessed, the samples included 60 data points reported as 8-hour TWAs that are derived from the
sum of same-day samples and a total of 25 short-term samples that were each taken over 30 minutes. All
of the 8-hour TWAs from the OSHA CEHD were non-detect for asbestos and 8-hour TWAs were
calculated using the asbestos LOD of 2,117.5 fibers/sample). These data are provided in Asbestos Part 2
Draft RE - Environmental Release and Occupational Exposure Data Tables - Fall 2023 (U.S. EPA.
20231).
EPA calculated the 95th percentile and 50th percentile of the available 85 data points for inhalation
exposure monitoring data to assess the high-end and central tendency exposures, respectively. Because
the geometric standard deviation of the data set was greater than three for the higher exposure-potential
worker inhalation exposure samples and less than three for lower exposure-potential workers and ONUs,
EPA used (1) half the detection limit for higher exposure-potential worker non-detect samples and (2)
the detection limit divided by the square root of two for both the lower exposure-potential worker non-
detect samples in the central tendency and high-end exposure calculations based on EPA's Guidelines
for Statistical Analysis of Occupational Exposure Data (U.S. EPA. 1994). Using these 8-hour TWA
exposure concentrations, EPA calculated the ELCR. Only one sample was found to measure short-term
inhalation exposure to ONUs. That sample was used to determine a high-end estimate while the central
tendency was estimated at half of the high-end estimate.
Area sampling data from the OSHA OECD were used to estimate exposure to ONUs, as EPA assumed
these samples were placed to measure the general room concentrations, which are likely to be similar to
ONU exposures. Brorbv et al. (2013) gathered monitoring data from historical sources on workers
sanding asbestos-containing joint compounds. Brorby et al. does not indicate whether this data is
personal breathing zone data; however, one of the historical sources referenced in the study specifies
that samples were taken "0.9-1.5m" away from the source (Brorbv et al.. 2013). EPA assumed all the
samples were PBZ samples and used them in the assessment for higher exposure-potential workers.
The exposure frequency for this exposure scenario is estimated at 250 days/year based on a worker
schedule of 5 days per week and 50 weeks per year. EPA estimated worker exposure over the full
working day, or 8 hours/day, as the data used to estimate inhalation exposures are 8-hour TWA data.
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The inhalation exposures are summarized for the three SEGs are provided in TableApx E-40,
TableApx E-41, and Table Apx E-42. Additional information regarding the ADC calculation is
provided in Appendix E.5.4.
Table Apx E-40. Summary of Inhalation Monitoring Data for Handling Articles and
Formulations for Higher-Exposure Potential Workers
Exposure Concentration
Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number of
Samples
Data Quality Rating
of Air Concentration
Data
Weight of
Scientific
Evidence
8-Hour TWA Exposure
Concentration
0.69
0.10
46
High
Moderate
Chronic, Non-cancer
ADC17
0.16
2.3E-02
30-Minute Short-Term
Exposure Concentration
8.8E-02
7.3E-02
16
Medium
Moderate
11 The ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated
using the 30-minute exposure concentrations presented here, averaged with 7.5 hours at the full shift (i.e.. 8-hour
TWA) exposure concentrations.
Table Apx E-41. Summary of Inhalation Monitoring Data for Handling Articles and
Formulations for Lower-Exposure Potential Workers
Exposure Concentration Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number of
Samples
Data Quality Rating
of Air
Concentration Data
Weight of
Scientific
Evidence
8-Hour TWA Exposure
Concentration
1.1E-02
8.3E-03
7
High
Moderate
Chronic, Non-cancer ADC"
2.5E-03
1.9E-03
30-Minute Short-Term
Exposure Concentration
4.2E-02
2.1E-02
8
High
Moderate
11 The ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated
using the 30-minute exposure concentrations presented here, averaged with 7.5 hours at the full shift (i.e., 8-hour
TWA) exposure concentrations.
Table Apx E-42. Summary of Inhalation Monitoring Data Handling Articles and Formulations
for ONUs
Exposure Concentration Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number of
Samples
Data Quality Rating
of Air
Concentration Data
Weight of
Scientific
Evidence
8-Hour TWA Exposure
Concentration
1.2E-03
1.1E-03
7
High
Moderate
Chronic, Non-cancer ADC"
2.6E-04
2.5E-04
30-Minute Short-Term
Exposure Concentration
1.5E-03
7.7E-04
1
High
Moderate
11 The ADC presented here is based on 8-hour TWA monitoring data. Short-term ADC estimates are calculated
using the 30-minute exposure concentrations presented here, averaged with 7.5 hours at the full shift (i.e., 8-hour
TWA) exposure concentrations.
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Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of the data used for this assessment is the use of directly applicable monitoring
data, which is preferrable to other assessment approaches such as modeling or the use of occupational
exposure limits. An additional strength is that the literature sources include information on worker
activities. The OSHA CEHD monitoring data does not include process information or worker activities;
therefore, there is uncertainty as to which worker activities these data cover and whether all potential
workers activities are represented in this data Additionally, the OSHA CEHD data only include data
from three sites. Therefore, EPA cannot determine the statistical representativeness of this data (e.g.,
high-end, central tendency) towards potential exposures from this condition of use. Furthermore, it is
unclear how representative the data are for all sites and all workers across the United States. Differences
in work practices and engineering controls across sites can introduce variability and limit the
representativeness of any one site relative to all sites. As discussed above, EPA used half the detection
limit for the non-detect values or divided the non-detect values by the square root of two in the central
tendency and high-end exposure calculations. This introduces uncertainty into the assessment because
the true value of asbestos is unknown (though expected to be between zero and the LOD).
E.14 Handling of Vermiculite Products for Agriculture and Lab Chemicals
E.14.1 Process Description
Vermiculite is used in occupational settings as a soil treatment product for agricultural purposes and as a
packaging/disposal material for laboratory purposes. Regarding agricultural uses of vermiculite in
occupational settings (e.g., landscaping), it is common for agricultural workers to mix a vermiculite
product with soil and then spread the treated soil across some defined area. During the mixing and
spreading of vermiculite containing materials, friable components within the mixture may become
airborne which could lead to releases and worker exposure. Regarding laboratory uses, vermiculite is
typically used by laboratory workers to absorb chemicals before incineration (TFtC World. 2023).
However, friable components of the vermiculite packaging material may become airborne during
handling. The expected extent of asbestos releases and exposures are qualitatively assessed in Appendix
E.14.2, which provides a qualitative assessment of exposure to asbestos from agricultural and laboratory
uses of vermiculite products.
E.14.2 Qualitative Assessment
Based on information identified in EPA's "Sampling and Analysis of Consumer Garden
Products That Contain Vermiculite" document (U.S. EPA. 2000a). asbestos has been identified in some
lawn and gardening care products that contained vermiculite, as well as a vermiculite product used to
package and dispose of laboratory chemicals. Specifically, the EPA study investigated 38 vermiculite
products that were available nationwide, and asbestos was found in 5 of the vermiculite products. The
sources of the vermiculite for the products investigated in the EPA study included one mine in Libby,
Montana; one mine in South Africa; and various mines across the United States (U.S. EPA. 2000a).
Asbestos measurements from products sourced from the Libby, Montana, mine showed slightly higher
concentrations (up to 2.79 percent), whereas asbestos concentrations from other vermiculite products
were below 1 percent as measured by transmission electron microscopy (TEM). The use of pesticides,
including herbicides and fungicides, is regulated under the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA) and is not assessed in this risk evaluation. However, the use of fertilizers and
non-pesticidal lawncare products is under the purview of TSCA and is assessed in this draft risk
evaluation.
The EPA study of vermiculite products simulated the preparation of potting soil by mixing 50 percent
vermiculite and 50 percent peat moss. The researchers then simulated potting plants by emptying a
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container of soil into a plastic tub and manipulating the soil to break up clods. The soil was placed in
plastic pots, which were emptied back into the plastic tub, and the work area was then cleaned by
sweeping loose spilled soil back into the plastic tub. This simulation was run three times for each of the
asbestos-containing vermiculite products (U.S. EPA. 2000a). Airborne asbestos fibers were detected
during the simulated use of one product only (i.e., Zonolite Chemical Packaging Vermiculite), which is
used to pack laboratory chemicals for transport or disposal. The asbestos-containing product, Zonolite
Chemical Packaging Vermiculite, was sourced from a mine in Libby, Montana, which closed in 1990.
Because current uses of vermiculite products mined from Libby are not expected, the airborne asbestos
measurements from simulated use of Zonolite Chemical Packaging Vermiculite are not representative of
ongoing uses. None of the other asbestos-contaminated vermiculite products used in lawn care released
measurable quantities of airborne asbestos fibers during simulated use (U.S. EPA. 2000a). Because
currently available vermiculite products do not contain significant levels of asbestos, EPA does not
expect any significant asbestos releases or occupational exposures from the commercial use of these
products based on the data from the EPA analysis of vermiculite products. Therefore, the use of
vermiculite for agricultural and laboratory purposes is not further assessed in this risk evaluation.
E.15 Industrial Mining of Non-asbestos Commodities
Asbestos mining ceased in the United States in 2002 (Lucarelli. 2002); therefore, asbestos mining is not
considered in this draft risk evaluation. Instead, this risk evaluation considers only the industrial mining
of non-asbestos commodities (e.g., talc and vermiculite). The expected extent of asbestos releases and
exposures from mining of non-asbestos commodities are qualitatively assessed in Appendix E.15.2.
E.15.1 Process Description
Asbestos can be found in deposits in the ground and can be uncovered unintentionally during the mining
of non-asbestos commodities. During industrial mining of non-asbestos commodities, friable
components within the mined material may become airborne that could lead to releases and/or worker
exposure. Vermiculite and talc mining operations, as well as general commodity mining operations, are
described below.
Vermiculite and Talc Mining
Vermiculite ore is primarily mined using open-pit methods where rock and minerals are removed from
the surface in order to reach and extract the ore—typically accomplished using conventional drilling and
blasting methods (U.S. EPA. 1995a. b). Over 95 percent of the talc ore produced in the United States
also comes from open-pit mines. Crude vermiculite and talc ore is typically transported from the mine
by truck (U.S. EPA. 1995a. b).
Vermiculite and talc are minerals exist as shiny flakes in physical form. If vermiculite or talc are mined
from ore that also contains asbestos fibers, it is possible that the resulting vermiculite or talc minerals are
contaminated with asbestos fibers. One study found that raw talc ore contained 37 to 59 percent
tremolite asbestos (NIOSH. 1980). In 2020, two companies with mining and processing facilities in
South Carolina and Virginia produced approximately 100,000 tons of vermiculite (USGS. 2021). In
2021, domestic production of crude talc was estimated to be 490,000 tons, with the majority mined in
Montana, Texas, and Vermont (USGS. 2022).
MSHA reported that there were 6,413 total active mines as of 2022 (MSHA. 2022b). Of these active
mines, 14 are engaged in the mining talc or vermiculite (no asbestos mines are still active). Collectively,
these 14 active mines employ an average of 30 mill operation workers and 9 strip/quarry/open pit
workers per site (MSHA. 2022b). Control methods in vermiculite and talc mines include ventilation, wet
drilling, and water sprays for dust suppression (NIOSH. 1980). MSHA recommends the use of NIOSH-
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approved respirators and disposable protective clothing during mining in the presence of asbestos. If
disposable clothing is not available, work clothes should be vacuumed using a specially designed
asbestos vacuum before being removed (MSHA. 2000). EPA did not find information on operating
schedules during vermiculite and talc mining. Multiple sources suggest that commodity mines like iron
ore and coal mines operate 365 days per year; therefore it can be assumed that talc and vermiculite
mines would have similar operating schedules (Maisev and et al.. 2020; SafeStart 2017).
All Other Mining Commodities
Asbestos is found naturally in irregular veins scattered throughout rock masses in various parts of the
world (Archer and Blackwood. 1979). These natural deposits of asbestos can be disturbed during
traditional mining operations, leading to exposures and releases (CDM Federal Programs Corporation.
2015). The most common general mining practices include surface (open-pit) mining, where ore is
extracted from the ground by digging with heavy machinery, and underground mining, where holes are
drilled deep into the earth with explosives and drill rigs (AmerMine Serv. 2023). Most recovered ores
are transported from mines in trucks and rail cars, which may be subsequently transferred to ships
(Cargo Handbook. 2023). Due to the wide range of mined commodities, EPA was unable to find specific
throughputs or asbestos contamination levels by commodity.
According to the MSHA's Mine Data Retrieval System, average annual employment at mines from
1983 to 2021 was 259,104 workers, not including office workers (MSHA. 2022b). This includes an
average of 67,546 underground workers and 195,551 surface and facility workers per year. Out of these
workers, it is estimated that 44,000 miners and mine workers may have been exposed where asbestos
may have been a contaminant (IARC. 2012c). MSHA reported that there were 6,413 active mines in the
United States as of 2022. As noted above, MSHA recommends the use of NIOSH-approved respirators
and disposable protective clothing during mining in the presence of asbestos. If disposable clothing is
not available, work clothes should be vacuumed using a specially-designed asbestos vacuum before
being removed (MSHA. 2000). Because multiple sources suggest that commodity mines like iron ore
and coal mines operate 365 days per year (Maisev and et al.. 2020; SafeStart. 2017). talc and vermiculite
mines are assumed to have similar, year-round operating schedules.
E.15.2 Qualitative Assessment
EPA considered MSHA asbestos air monitoring data from 2005 through 2022 from industrial mining of
non-asbestos commodities which showed a limited number of non-zero values post 2008 (MSHA.
2022a). This data builds on sampling that was conducted as part of the 2008 MSHA rulemaking to lower
the 8-hour, TWA, full-shift personal exposure limit (PEL) for asbestos from 2 fibers per cubic
centimeter of air (f/cc) to 0.1 f/cc at all metal and nonmetal mines, surface coal mines, and surface areas
of underground coal mines (MSHA. 2022a). EPA consulted with its federal partners and outside
stakeholders to determine the appropriate level of assessment for this COU.
The level of consideration or assessment afforded to a particular COU in a risk evaluation may vary.
EPA is not required to conduct a quantitative assessment of every hazard, exposure, COU, or PESS that
is within the scope of the risk evaluation. TSCA section 6(b)(4)(D) directs EPA to "publish the scope of
the risk evaluation to be conducted, including the hazards, exposures, conditions of use, and the
potentially exposed or susceptible subpopulations [EPA] expects to consider" (emphasis added). TSCA
section 6(b)(4)(F) further instructs EPA, when conducting risk evaluations, to "take into account, where
relevant, the likely duration, intensity, frequency, and number of exposures under the conditions of use
of the chemical substance" (emphasis added). Thus, EPA may conduct qualitative assessments or may
elect to "consider" or "account for" certain conditions of use without formal assessments. EPA has
incorporated such "fit-for-purpose" considerations into the Risk Evaluation Rule (see 40 CFR 702.41(a);
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82 FR 33726, 33739-40 (July 20, 2017) ("all conditions of use evaluated will not warrant the same level
of evaluation").
In determining the appropriate level of assessment of industrial mining of non-asbestos commodities in
this risk evaluation, the Agency has considered the duration, intensity, frequency, and/or number of
exposures to asbestos from this type of activity. Based on the data considered and the information from
MSHA and outside stakeholders, EPA has determined that exposure to asbestos is unlikely. The
information from MSHA shows that since the revised PEL was finalized in 2008 nearly all air
monitoring samples were non-detects (MSHA. 2022a). Additionally, EPA was provided with several
sources of information that selective mining practices occur and are successful in generally avoiding
deposits that are likely to contain asbestos minerals. Therefore, the Agency will not conduct any further
analysis of this COU in this draft risk evaluation.
E.16 Waste Handling, Disposal, and Treatment
E.16.1 Process Description
Each of the COU of asbestos may generate waste streams of the chemical that are collected and
transported to third-party sites for disposal or treatment. Industrial sites that treat or dispose on-site
wastes that they themselves generate are assessed in each COU assessment. Wastes of asbestos that are
generated during a COU and sent to a third-party site for treatment or disposal may include the
following:
Wastewater
Asbestos may be contained in wastewater discharged to POTW or other, non-public treatment works for
treatment. Industrial wastewater containing asbestos discharged to a POTW may be subject to EPA or
authorized NPDES state pretreatment programs. The assessment of wastewater discharges to POTWs
and non-public treatment works of asbestos is included in each of the condition of use assessments in
Appendix E.10 through Appendix E.13.
Solid Wastes
Solid wastes are defined under RCRA as any material that is discarded by being (1) abandoned, (2)
inherently waste-like, or (3) a discarded military munition. Solid wastes may subsequently meet
RCRA's definition of hazardous waste by either being listed as a waste at 40 CFR 261.30 to 261.35 or
by meeting waste-like characteristics as defined at 40 CFR 261.20 to 261.24. Solid wastes that are
hazardous wastes are regulated under the more stringent requirements of Subtitle C of RCRA, whereas
non-hazardous solid wastes are regulated under the less stringent requirements of Subtitle D of RCRA.
Asbestos containing wastes are any wastes that contain one percent or more of asbestos by weight.
Friable asbestos waste contains more than one-percent asbestos and can be crumbled, pulverized, or
recued to powder under hand pressure. Non-friable asbestos waste is treated as either construction and
demolition or municipal solid waste and can be disposed of in a municipal landfill. Friable asbestos
waste is considered a "non-RCRA" hazardous waste and is not subject to RCRA subtitle C regulation
and can be disposed in a municipal landfill but special requirements for containerization, transportation,
recordkeeping and disposal are needed.
2019 TRI data lists 15 off-site transfers of asbestos to land disposal, and none to wastewater treatment,
incineration, or recycling facilities (U.S. EPA. 2019a).
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Municipal Waste Landfill
Municipal solid waste landfills are discrete areas of land or excavated sites that receive household
wastes and other types of non-hazardous wastes (e.g., industrial and commercial solid wastes).
Standards and requirements for municipal waste landfills include location restrictions, composite liner
requirements, leachate collection and removal system, operating practices, groundwater monitoring
requirements, closure-and post-closure care requirements, corrective action provisions, and financial
assurance. Non-hazardous solid wastes are regulated under RCRA Subtitle D, but states may impose
more stringent requirements.
Landfill activities include compacting refuse at the working face, moving soil for cover, and utilizing
equipment to move wastes (Esswein and Tubbs. 1994). Municipal solid wastes may be first unloaded at
waste transfer stations for temporary storage prior to being transported to the landfill or other treatment
or disposal facilities.
Hazardous Waste Landfill
Hazardous waste landfills are excavated or engineered sites specifically designed for the final disposal
of non-liquid hazardous wastes. Design standards for these landfills require double liner, double leachate
collection and removal systems, leak detection system, run on, runoff and wind dispersal controls, and
construction quality assurance program (U.S. EPA. 2018b). There are also requirements for closure and
post-closure, such as the addition of a final cover over the landfill and continued monitoring and
maintenance. These standards and requirements prevent potential contamination of groundwater and
nearby surface water resources. Hazardous waste landfills are regulated under Part 264/265, Subpart N.
Asbestos can be disposed of only at certified landfills registered to handle asbestos. When disposing of
asbestos, arrangements are made prior to delivery to the landfill (Hawkins et al.. 1988). All fibrous and
dusty asbestos wastes are accepted at a landfill site only in robust plastic sacks or similar wrapping. On
arrival, the delivery vehicle is directed to the designated drop-off area. The waste is then deposited in
excavated trenches, and at least 5 meters of other wastes are immediately spread over the bagged
asbestos (Mimides et al.. 1997).
E.16.2 Facility Estimates
CDR data were not available for this OES. Therefore, EPA used BLS and SUSB data to estimate the
number of establishments. Because it is assumed that employees work only at the employment
establishment, the number of establishments is considered equal to the number of sites for this OES.
EPA assumed that establishments involved in waste handling, disposal, and treatment of asbestos are
classified under the applicable NAICS codes 221117 (Biomass Electric Power Generation), 562211
(Hazardous Waste Treatment and Disposal), 562212 (Solid Waste Landfill), 562920 (Materials
Recovery Facilities), and 562998 (All Other Miscellaneous Waste Management Services). Based on the
2021 County Business Patterns data published by the U.S. Census Bureau, there are 4,972
establishments classified under these NAICS codes. This provides a high-end bounding estimate for the
number of sites for this OES.
E.16.3 Release Assessment
E.16.3.1 Environmental Release Points
EPA expects releases to occur during waste handling, disposal, and treatment. As stated in the process
description, each of the conditions of use may generate waste streams of the asbestos that are collected
and transported to third-party sites for disposal or treatment. Wastes of asbestos that are generated and
sent to a third-party site for treatment or disposal may include wastewater and solid wastes.
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E.16.3.2 Environmental Release Assessment Results
EPA estimated releases from this OES using TRI and NEI data, as described in Appendix E.4. TRI data
were available for water, air, and land disposals, NEI data were available for air emissions. In summary,
EPA estimated daily emissions for this OES by calculating the 50th and 95th percentile of all reported
annual releases and dividing the results by 250 release days/yr determined in Appendix E.4.4.
Based on the available data, EPA expects asbestos releases to air (fugitive and stack) and landfills.
However, EPA does not expect wastewater discharges of asbestos during this OES, since the data
gathered shows no discharges of asbestos to water. Each OES contained reporting sites from TRI from
other medias of release, but not to water. Therefore, EPA assumed that there are no wastewater
discharges of asbestos from this OES. Although there may be incidental discharges of asbestos, EPA
expects those releases to be low.
A summary of daily environmental release estimates by media for this OES are provided in Table 3-8. In
addition, TableApx E-43 and TableApx E-44 below present a summary of annual and daily releases
estimates to air and land, respectively. For the raw data set used in making these estimations, see
Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure Data Tables - Fall 2023
(U.S. EPA. 2023iY
Table Apx E-43. Air
Emission Summary
or Waste Handling, Disposal, and Treatment
Annual Fugitive
Emissions
(kg/site-year)
Annual Stack
Emissions
(kg/site-year)
Number of
Operating
Days
Daily Fugitive
Emissions
(kg/site-day)
Daily Stack Emissions
(kg/site-day)
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
1.6
18
0.23
24
250
6.3E-03
7.4E-02
9.1E-04
9.5E-02
Table Apx E-44. Land Release Summary for Waste Handling, Disposal, and Treatment
Annual Land Disposals"
(kg/site-year)
Number of
Operating Days
Daily Land Disposals
(kg/site-day)
Central Tendency
High-End
Central Tendency
High-End
191,200
2,608,482
250
765
10,434
"Total land disposals include the following land disposal methods: RCRA Subtitle C Landfills, Other On-site
Landfills, Other Off-site Landfills, Other Off-site Management, Solidification/Stabilization Treatment, and Unknown.
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of these estimates is that EPA used multiple years of data in the analysis. A
strength of TRI data is that TRI compiles the best readily available release data for all reporting
facilities. A strength of NEI data is that it includes comprehensive and detailed estimates of air
emissions from point and area sources. The primary limitation to this assessment is that information on
the COUs of asbestos at facilities in TRI and NEI is limited. Additional limitations to this assessment
include the assumptions on the number of operating days to estimate daily releases, the assumption of no
wastewater discharges where not reported in TRI, and the uncertainty in the mapping of reporting
facilities to this OES.
For purposes of release assessment, it is assumed that the included data sufficiently represent all OES
activities, and that all releases take place uniformly over time, as opposed to all at once or at varying
Page 308 of 405
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intensities. Assessing environmental releases using TRI and NEI data presents various sources of
uncertainty. TRI data are self-reported and have reporting requirements that exclude certain facilities
from reporting. Facilities are only required to report to TRI if the facility has 10 or more full-time
employees, is included in an applicable NAICS code, and manufactures, processes, or uses the chemical
in quantities greater than a certain threshold (25,000 lb for manufacturers and processors and 10,000 lb
for users). NEI reporting of hazardous air pollutants, such as asbestos, is voluntary. Therefore, NEI may
not include data from all emission sources. There is uncertainty in EPA's assumption of no wastewater
discharges for this OES, as there could be more sites that dispose of/treat asbestos waste that are below
the TRI reporting thresholds.
E.16.4 Occupational Exposure Assessment
E.16.4.1 Worker Activities
The waste from demolition sites may be sent to construction and demolition landfills, incineration
facilities, or recycled. Waste containing asbestos may be further broken down via shredders, or other
equipment at landfill and incineration facilities. Workers and ONUs at these sites may be exposed to
dust containing asbestos.
Solid waste may be first sent to waste transfer facilities, where waste is consolidated onto larger trucks.
At many transfer stations, workers screen incoming waste located on conveyor systems, tipping floors,
or in waste pits to identify recyclables and wastes inappropriate for disposal (e.g., hazardous waste,
whole tires). Workers at transfer stations operate heavy machinery such as conveyor belts, push blades,
balers, and compactors, and may also clean the facility or perform equipment maintenance. Workers
may be exposed to poor air quality due to dust and odor, particularly in tipping areas over waste pits
(Esswein and Tubbs. 1994).
As reported for a municipal landfill facility, waste may be dumped onto tipping floors for storage, then
fed to a conveyor system for sorting and eventual shredding of waste. The waste from these processes
are either directly loaded on trucks to be sent into the landfill or deposited in storage pits (Burkhart and
Short. 1995). Heavy machinery operators may be exposed to particulates and other contaminates while
in the cabs of the machinery (Esswein and Tubbs. 1994). Mechanics servicing equipment may be
exposed to residues on machinery. EPA expects similar processing of waste may occur at construction
and demolition landfills. At municipal waste combustors, waste materials are not generally handled
directly by workers. Trucks may dump the waste directly into a pit or be tipped to the floor and later
pushed into the pit by a worker operating a front-end loader. A large grapple from an overhead crane is
used to grab waste from the pit and drop it into a hopper where hydraulic rams feed the material
continuously into the combustion unit at a controlled rate.
E.16.4.2 Number of Workers and Occupational Non-users
EPA used workers and ONU estimates determined from an analysis of BLS data for the NAICS codes
562211, Hazardous Waste Treatment and Disposal; 562998, All Other Misc. Waste Management
Services; 562212, Solid Waste Landfill; 562920, Materials Recovery Facilities; and 221117, Biomass
Electric Power Generation. EPA assumes that all workers at these sites could potentially be exposed to
ACM (U.S. BLS. 2016). Data from the 2019 U.S. Census Bureau estimated a total of 4,972
establishments that operated under these NAICS codes. Based on these data, EPA estimated that a total
of five workers and nine ONUs are potentially exposed per establishment in this exposure scenario
TableApx E-45.
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TableApx E-45. Estimated Number of Workers Potentially Exposed to Asbestos During Waste
Disposal Activities
Number of
Establishments
Exposed
Workers per
Establishment
Exposed ONUs
per
Establishment
Total
Exposed
Workers"
Total ONUs"
Total
Exposed"
5E03
5
9
2.6E04
4.7E04
7.3E04
11 Totals have been rounded to two significant figures. Tota
s may not add exactly due to rounding.
E.16.4.3 Occupational Exposure Result
Workers may come into contact with friable asbestos while handling any asbestos-containing materials
that are disposed, either in waste transfer facilities, landfills (municipal or construction and demolition),
or at MWCs. The information and data quality evaluation to assess occupational exposures for workers
while handling asbestos-containing waste is listed in Table Apx E-4
Occupational exposures to asbestos during disposal activities were estimated by evaluating PBZ samples
from OSHA's Chemical Exposure Health Data (CEHD) (OSHA. 2020) along with a NIOSH HHE and
two other literature studies (see Table Apx E-4). This inhalation exposure assessment includes 95
measurements, reported as 8-hour TWAs, that are derived from the sum of same-day samples. The
majority of 8-hour TWAs from the OSHA CEHD were non-detect for asbestos, and 8-hour TWAs were
calculated using the asbestos LOD of 2,117.5 fibers/sample (see https://www.cdc.gov/niosh/docs/2003-
154/pdfs/7400.pdf). These data are shown in Asbestos Part 2 Draft RE - Environmental Release and
Occupational Exposure Data Tables - Fall 2023 (U.S. EPA. 2023i).
EPA calculated the 95th percentile and 50th percentile of the available 95 data points for inhalation
exposure monitoring data to assess the high-end and central tendency exposures for workers,
respectively. Because the geometric standard deviation of the data set was greater than three for the
exposure samples, EPA used half the detection limit to estimate the non-detect samples in the central
tendency and high-end exposure calculations based on EPA's Guidelines for Statistical Analysis of
Occupational Exposure Data (U.S. EPA. 1994). Using these 8-hour TWA exposure concentrations,
EPA calculated corresponding ADC values as shown in Appendix E.5.4.
EPA did not identify any inhalation exposure data for ONUs or short-term exposure data for workers or
ONUs. Therefore, the central tendency of worker inhalation exposure was used to approximate the high-
end inhalation exposure for ONUs. In general, EPA assumes that ONU exposure is lower than worker
exposure since ONUs are not expected to handle any ACM. These inhalation exposures are summarized
for workers in Table Apx E-46. Additional information regarding the ADC calculation is provided in
Appendix E.5.4.
The exposure frequency for this exposure scenario is estimated at 250 days/year based on a worker
schedule of five days per week and 50 weeks per year. EPA estimated worker exposure over the full
working day, or eight hours/day, as the data used to estimate inhalation exposures are 8-hour TWA data.
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TableApx E-46. Summary of Inhalation Monitoring Data for Workers Handling Asbestos-
Containing Waste
Exposure Concentration Type
High-End
(f/cc)
Central
Tendency
(f/cc)
Number of
Samples
Data Quality
Rating of Air
Concentration Data
Weight of
Scientific
Evidence
8-hour TWA Exposure
Concentration
3.2E-02
1.5E-03
95
High
Moderate
Chronic, Non-cancer ADC'1
7.2E-03
3.4E-04
30-min Short-Term Exposure
Concentration
-
-
11 The ADC presented here is based on 8-hour TWA monitoring data. Short-term exposure data were not available for
this scenario.
Strengths, Limitations, Assumptions, and Uncertainties
The primary strength of the data used for this assessment is the use of directly applicable monitoring
data, which is preferrable to other assessment approaches such as modeling or the use of occupational
exposure limits. An additional strength is that the literature sources include information on worker
activities. The OSHA CEHD monitoring data does not include process information or worker activities;
therefore, there is uncertainty as to which worker activities these data cover and whether all potential
workers activities are represented in this data. Additionally, it is unclear how representative the data are
for all sites and all workers across the United States. Differences in work practices and engineering
controls across sites can introduce variability and limit the representativeness of any one site relative to
all sites. There is uncertainty due to the non-detect values used in the assessment. As discussed above,
EPA used half the detection limit for the non-detect values in the central tendency and high-end
exposure calculations. This introduces uncertainty into the assessment because the true value of asbestos
is unknown (though expected to be between zero and the LOD).
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8623
8624
8625
E.17 Summary of Occupational Inhalation Exposure Assessment
Table Apx E-47. Summary of Occupational
Inhalation Exposure Assessment
Short-Term
8-Hour TWA
Chronic, Non-cancer
Exposures
Exposures
Exposures
8-Hour
Data
Points
Short-
OES
Category
Exposure
Scenario
Exposure
Frequency
C30-min (f/cc)
Cs-hr TWA (f/cc) "
ADCasbestos (f/cc)
Term
Data
Sources and
Notes
Data Type
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
Points
Maintenance,
Higher-
8-hr
50
N/A
N/A
0.43
1.1E-03
2.0E-02
5.1E-05
847
N/A
See Table Apx
Monitoring
renovation, and
demolition
Exposure
Workers
E-21
data
Maintenance,
Lower-
8-hr
50
N/A
N/A
0.22
1.1E-03
1.0E-02
5.1E-05
31
N/A
See Table Apx
Monitoring
renovation, and
Exposure
E-22
data
demolition
Workers
Maintenance,
ONU
8-hr
50
N/A
N/A
4.6E-02
1.2E-02
2.1E-03
5.6E-04
103
N/A
See Table Apx
Monitoring
renovation, and
E-23
data
demolition
Maintenance,
Higher-
30-min
50
0.16
2.5E-02
0.41
2.6E-03
1.9E-02
1.2E-04
N/A
145
See Table Apx
Monitoring
renovation, and
demolition
Exposure
Workers
E-21
data
Maintenance,
Lower-
30-min
50
2.5E-02
2.5E-02
0.21
2.6E-03
9.5E-03
1.2E-04
N/A
5
See Table Apx
Monitoring
renovation, and
Exposure
E-22
data
demolition
Workers
Maintenance,
ONU
30-min
50
5.3E-02
2.7E-02
4.6E-02
1.3E-02
2.1E-03
6.0E-04
N/A
1
See Table Apx
Monitoring
renovation, and
E-23
data
demolition
Firefighting and
other disaster
Firefighter
(Career)
8-hr
3
No data
available
No data
available
0.39
2.0E-02
1.1E-03
5.5E-05
62
No data
available
See Table Apx
E-28
Monitoring
data
response activities
Firefighting and
other disaster
Firefighter
(Volunteer)
8-hr
1
No data
available
No data
available
0.39
2.0E-02
3.5E-04
1.8E-05
62
No data
available
See Table Apx
E-29
Monitoring
data
response activities
Use, repair, or
Worker
8-hr
250
N/A
N/A
0.16
8.4E-03
3.6E-02
1.9E-03
216
N/A
See Table Apx
Monitoring
removal of industrial
E-34
data
and commercial
appliances or
machinery
containing asbestos
'or Asbestos
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Short-Term
8-Hour TWA
Chronic, Non-cancer
Exposures
Exposures
Exposures
8-Hour
Data
Points
Short-
OES
Category
Exposure
Scenario
Exposure
Frequency
C30-min (f/cc)
Cs-hr TWA (f/cc) "
ADCasbestos (f/cc)
Term
Data
Sources and
Notes
Data Type
High-
End
Central
Tendency
High-
End
Central
Tendency
High-
End
Central
Tendency
Points
Use, repair, or
ONU
8-hr
250
No data
No data
4.9E-02
2.8E-02
1.1E-02
6.4E-03
20
No data
See Table Apx
Monitoring
removal of industrial
available
available
available
E-35
data
and commercial
appliances or
machinery
containing asbestos
Use, repair, or
Worker
30-min
250
0.17
1.9E-02
0.16
9.1E-03
3.6E-02
2.1E-03
N/A
37
See Table Apx
Monitoring
removal of industrial
E-34
data
and commercial
appliances or
machinery
containing asbestos
Handling articles or
formulations that
Higher-
Exposure
8-hr
250
N/A
N/A
0.69
0.10
0.16
2.3E-02
46
N/A
See Table Apx
E-40
Monitoring
data
contain asbestos
Workers
Handling articles or
Lower-
8-hr
250
N/A
N/A
1.1E-02
8.3E-03
2.5E-03
1.9E-03
7
N/A
See Table Apx
Monitoring
formulations that
Exposure
E-41
data
contain asbestos
Workers
Handling articles or
ONU
8-hr
250
N/A
N/A
1.2E-03
1.1E-03
2.6E-04
2.5E-04
7
N/A
See Table Apx
Monitoring
formulations that
E-42
data
contain asbestos
Handling articles or
formulations that
Higher-
Exposure
30-min
250
8.8E-02
7.3E-02
0.66
9.8E-02
0.15
2.2E-02
N/A
16
See Table Apx
E-40
Monitoring
data
contain asbestos
Workers
Handling articles or
Lower-
30-min
250
4.2E-02
2.1E-02
1.3E-02
9.0E-03
3.0E-03
2.1E-03
N/A
8
See Table Apx
Monitoring
formulations that
Exposure
E-41
data
contain asbestos
Workers
Handling articles or
ONU
30-min
250
1.5E-03
7.7E-04
1.2E-03
1.1E-03
2.7E-04
2.5E-04
N/A
1
See Table Apx
Monitoring
formulations that
E-42
data
contain asbestos
Waste handling,
Worker
8-hr
250
No data
No data
3.2E-02
1.5E-03
7.2E-03
3.4E-04
95
N/A
See Table Apx
Monitoring
disposal, and
available
available
E-46
data
treatment
Waste handling,
ONU
8-hr
250
No data
No data
1.5E-03
-
N/A
N/A
No data
No data
ONU exposure
Surrogate
disposal, and
available
available
available
available
assessed at
monitoring
treatment
central tendency
of worker
exposure
data
" 8-hour TWA values for short-term (30-minute) exposures are adjusted using measured 8-hour TWA concentrations using the following equation: (0.5 x [Short-term concentration] + 7.5 x
[Measured 8-hour TWA]) / 8.
8626
Page 313 of 405
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8627
8628
8629
8630
8631
8632
8633
8634
8635
8636
8637
8638
8639
8640
8641
8642
8643
8644
8645
8646
8647
8648
8649
8650
8651
8652
8653
8654
8655
8656
8657
8658
8659
8660
8661
8662
PUBLIC RELEASE DRAFT
April 2024
E.18 Example of Estimating Number of Workers and Occupational Non-
users
This appendix summarizes the methods that EPA/OPPT used to estimate the number of workers who are
potentially exposed to asbestos in each of its occupational exposure scenarios. The method consists of
the following steps:
1. Identify NAICS codes for the industry sectors associated with each COU;
2. Estimate total employment by industry/occupation combination using the BLS Occupational
Employment Statistics (BLS OES) data (U.S. BLS. 2016);
3. Refine the BLS OES estimates where they are not sufficiently granular by using SUSB data on
total employment by 6-digit NAICS;
4. Estimate the number of establishments and number of potentially exposed employees per
establishment; and
5. Estimate the number of potentially exposed employees within the COU.
Step 1: Identifying Affected NA ICS Codes
As a first step, EPA/OPPT identified NAICS industry codes associated with each COU. EPA/OPPT
generally identified NAICS industry codes for a COU by the following:
• Querying the U.S. Census Bureau's NAICS Search tool using keywords associated with each
condition of use to identify NAICS codes with descriptions that match the COU.
• Referencing EPA/OPPT Generic Scenarios (GSs) and OECD ESDs for a COU to identify
NAICS codes cited by the GS or ESD.
• Reviewing CDR data for the chemical, identifying the industrial sector codes reported for
downstream industrial uses, and matching those industrial sector codes to NAICS codes using
Table D-2 provided in the CDR reporting instructions.
Each COU in the main body of this report identifies the NAICS codes EPA/OPPT identified for the
respective condition of use.
Step 2: Estimating Total Employment by Industry and Occupation
BLS' (2016) OES data provide employment data for workers in specific industries and occupations. The
industries are classified by NAICS codes (identified previously), and occupations are classified by
Standard Occupational Classification (SOC) codes.
Among the relevant NAICS codes (identified previously), EPA/OPPT reviewed the occupation
description and identified those occupations (SOC codes) where workers are potentially exposed to
asbestos Table Apx E-48 shows the SOC codes EPA/OPPT classified as occupations potentially
exposed to asbestos. These occupations are classified into workers (W) and occupational non-users (O).
All other SOC codes are assumed to represent occupations where exposure is unlikely.
Page 314 of 405
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PUBLIC RELEASE DRAFT
April 2024
8663 TableApx E-48. SOCs with Worker and ONU Designations for All Occupational Exposure
8664 Scenarios
soc
Occupation
Designation
11-9020
Construction Managers
O
11-9040
Architectural and Engineering Managers
O
17-2010
Aerospace Engineers
O
17-2050
Civil Engineers
O
17-2070
Electrical and Electronics Engineers
O
17-2110
Industrial Engineers, Including Health and Safety
O
17-3022
Civil Engineering Technicians
W
25-4013
Museum Technicians and Conservators
W
33-1020
First-Line Supervisors of Fire Fighting and Prevention Workers
O
33-2000
Fire Fighting and Prevention Workers
W
33-3050
Police Officers
O
37-1010
First-Line Supervisors of Building and Grounds Cleaning and Maintenance
Workers
O
37-1011
First-Line Supervisors of Housekeeping and Janitorial Workers
O
37-2010
Building Cleaning Workers
W
37-3000
Grounds Maintenance Workers
W
47-1000
Supervisors of Construction and Extraction Workers
O
47-2010
Boilermakers
W
47-2020
Brickmasons, Blockmasons, and Stonemasons
W
47-2030
Carpenters
W
47-2040
Carpet, Floor, and Tile Installers and Finishers
W
47-2050
Cement Masons, Concrete Finishers, and Terrazzo Workers
W
47-2060
Construction Laborers
W
47-2070
Construction Equipment Operators
W
47-2080
Drywall Installers, Ceiling Tile Installers, and Tapers
W
47-2110
Electricians
W
47-2130
Insulation Workers
W
47-2140
Painters and Paperhangers
O
47-2150
Pipelayers, Plumbers, Pipefitters, and Steamfitters
w
47-2160
Plasterers and Stucco Masons
w
47-2180
Roofers
w
47-2210
Sheet Metal Workers
0
47-3000
Helpers, Construction Trades
w
47-4010
Construction and Building Inspectors
0
47-4020
Elevator Installers and Repairers
0
47-4040
Hazardous Materials Removal Workers
w
47-4099
Construction and Related Workers, All Other
w
49-1000
Supervisors of Installation, Maintenance, and Repair Workers
0
49-2091
Avionics Technicians
w
49-2094
Electrical and Electronics Repairers, Commercial and Industrial Equipment
w
49-2095
Electrical and Electronics Repairers, Powerhouse, Substation, and Relay
w
49-3010
Aircraft Mechanics and Service Technicians
w
49-3042
Mobile Heavy Equipment Mechanics, Except Engines
w
49-9010
Control and Valve Installers and Repairers
w
49-9040
Industrial Machinery Installation, Repair, and Maintenance Workers
w
49-9070
Maintenance and Repair Workers, General
w
49-9098
Helpers-Installation, Maintenance, and Repair Workers
w
51-2010
Aircraft Structure, Surfaces, Rigging, and Systems Assemblers
w
Page 315 of 405
-------
8665
8666
8667
8668
8669
8670
8671
8672
8673
8674
8675
8676
8677
8678
8679
8680
8681
8682
8683
8684
8685
8686
8687
8688
8689
8690
8691
8692
8693
8694
8695
8696
8697
8698
PUBLIC RELEASE DRAFT
April 2024
SOC
Occupation
Designation
51-4050
Metal Furnace Operators, Tenders, Pourers, and Casters
W
51-4120
Welding, Soldering, and Brazing Workers
W
51-8020
Stationary Engineers and Boiler Operators
W
51-9050
Furnace, Kiln, Oven, Drier, and Kettle Operators and Tenders
W
53-3032
Heavy and Tractor-Trailer Truck Drivers
O
53-5010
Sailors and Marine Oilers
W
53-5020
Ship and Boat Captains and Operators
O
53-5030
Ship Engineers
W
53-7000
Material Moving Workers
O
W = worker c
esignation; O = ONU designation
After identifying relevant NAICS and SOC codes, EPA/OPPT used BLS data to determine total
employment by industry and by occupation based on the NAICS and SOC combinations. For example,
there are 66,772 employees associated with 6-digit NAICS 236118 (Residential Building Construction)
and 47-2060 (Construction Laborers).
Using a combination of NAICS and SOC codes to estimate total employment provides more accurate
estimates for the number of workers than using NAICS codes alone. Using only NAICS codes to
estimate number of workers typically result in an overestimate because not all workers employed in that
industry sector will be exposed. However, in some cases, BLS only provide employment data at the 4-
or 5-digit NAICS level; therefore, further refinement of this approach may be needed (see next step).
Step 3: Refining Employment Estimates to Account for Lack of NA ICS Granularity
The third step in EPA/OPPT's methodology was to further refine the employment estimates by using
total employment data in the SUSB (U.S. Census Bureau. 2015). In some cases, BLS OES occupation-
specific data are only available at the 4- or 5-digit NAICS level, whereas the SUSB data are available at
the 6-digit level (but are not occupation-specific). Identifying specific 6-digit NAICS will ensure that
only industries with potential asbestos exposure are included. As an example, OES data are available for
the 4-digit NAICS 3251 Basic Chemical Manufacturing, which includes the following 6-digit NAICS:
• NAICS 325110 Petrochemical Manufacturing;
• NAICS 325120 Industrial Gas Manufacturing;
• NAICS 325130 Synthetic Dye and Pigment Manufacturing;
• NAICS 325180 Other Basic Inorganic Chemical Manufacturing;
• NAICS 325193 Ethyl Alcohol Manufacturing;
• NAICS 325194 Cyclic Crude, Intermediate, and Gum and Wood Chemical Manufacturing; and
• NAICS 325199 All Other Basic Organic Chemical Manufacturing.
In this example, only NAICS 325199 is of interest. The Census data allow EPA/OPPT to calculate
employment in the specific 6-digit NAICS of interest as a percentage of employment in the BLS 4-digit
NAICS.
The 6-digit NAICS 325199 comprises 43 percent of total employment under the 4-digit NAICS 3251.
This percentage can be multiplied by the occupation-specific employment estimates given in the BLS
OES data to further refine our estimates of the number of employees with potential exposure.
Table_Apx E-49 illustrates this granularity adjustment for NAICS 325199.
Page 316 of 405
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April 2024
8699 TableApx E-49. Estimated Number of Potentially Exposed Workers and ONUs under NAICS
8700 325199
NAICS
soc
CODE
SOC Description
Occupation
Designation
Employment by
SOC at 4-Digit
NAICS Level
% of Total
Employment
Estimated
Employment by
SOC at 6-Digit
NAICS Level
3251
11-9020
Construction
Managers
O
22
43
9
3251
11-9040
Architectural and
Engineering Managers
O
332
43
143
3251
17-2050
Civil Engineers
0
69
43
30
3251
17-2070
Electrical and
Electronics Engineers
0
190
43
82
3251
17-2110
Industrial Engineers,
Including Health and
Safety
0
1,169
43
503
3251
37-2010
Building Cleaning
Workers
w
129
43
55
3251
37-3000
Grounds Maintenance
Workers
w
22
43
9
3251
47-1000
Supervisors of
Construction and
Extraction Workers
0
17
43
7
3251
47-2010
Boilermakers
w
13
43
6
3251
47-2070
Construction
Equipment Operators
w
142
43
61
3251
47-2110
Electricians
w
358
43
154
3251
47-2150
Pipelayers, Plumbers,
Pipefitters, and
Steamfitters
w
65
43
28
3251
49-1000
Supervisors of
Installation,
Maintenance, and
Repair Workers
0
712
43
306
3251
49-2094
Electrical and
Electronics Repairers,
Commercial and
Industrial Equipment
w
461
43
198
3251
49-9010
Control and Valve
Installers and
Repairers
w
121
43
52
3251
49-9040
Industrial Machinery
Installation, Repair,
and Maintenance
Workers
w
2,488
43
1070
3251
49-9070
Maintenance and
Repair Workers,
General
w
2,393
43
1029
3251
49-9098
Helpers-Installation,
Maintenance, and
Repair Workers
w
39
43
17
Page 317 of 405
-------
8701
8702
8703
8704
8705
8706
8707
8708
8709
8710
8711
8712
8713
8714
8715
8716
8717
8718
8719
8720
8721
8722
8723
8724
8725
8726
PUBLIC RELEASE DRAFT
April 2024
NAICS
SOC
CODE
SOC Description
Occupation
Designation
Employment by
SOC at 4-Digit
NAICS Level
% of Total
Employment
Estimated
Employment by
SOC at 6-Digit
NAICS Level
3251
51-4120
Welding, Soldering,
and Brazing Workers
W
112
43
48
3251
51-8020
Stationary Engineers
and Boiler Operators
W
190
43
82
3251
51-9050
Furnace, Kiln, Oven,
Drier, and Kettle
Operators and Tenders
w
47
43
20
3251
53-3032
Heavy and Tractor-
Trailer Truck Drivers
0
2,385
43
1,026
3251
53-7000
Material Moving
Workers
0
2,243
43
964
Total Potentially Exposed Employees
13,719
43
5,899
Total Workers
6,580
43
2,829
Total Occupational Non-users
7,139
43
3,070
Source: (U.S. Census Bureau. 2015); (U.S. BLS. 2016)
Note: numbers may not sum exactly due to rounding.
W = worker; O = occupational non-user
Step 4: Estimating the Number of Workers per Establishment
EPA/OPPT calculated the number of workers and ONUs in each industry/occupation combination using
the formula below (granularity adjustment is only applicable where SOC data are not available at the 6-
digit NAICS level): Number of Workers or ONUs in NAICS/SOC (Step 2) x Granularity Adjustment
Percentage (Step 3) = Number of Workers or ONUs in the Industry/Occupation Combination
EPA/OPPT then estimated the total number of establishments by obtaining the number of establishments
reported in the U.S. Census Bureau's SUSB (U.S. Census Bureau. 2015) data at the 6-digit NAICS
level.
Next, EPA/OPPT summed the number of workers and ONUs across all occupations within a NAICS
code and divided these sums by the number of establishments in the NAICS code to calculate the
average number of workers and occupational non-users per establishment.
Step 5: Estimating the Number of Workers and Establishments for a COU
EPA/OPPT estimated the number of workers and ONUs potentially exposed to asbestos and the number
of sites that use asbestos in a given COU through the following steps:
5. A Obtaining the number of establishments from SUSB (U.S. Census Bureau. 2015) at the 6-
digit NAICS level (Step 3) for each NAICS code in the condition of use and summing these
values; and
5.B Estimating the number of workers and occupational non-users potentially exposed to
asbestos by taking the number of establishments calculated in Step 5. A and multiplying it by
the average number of workers and occupational non-users per site from Step 4.
Page 318 of 405
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8727
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8729
8730
8731
8732
8733
8734
8735
8736
8737
8738
8739
8740
8741
8742
8743
8744
8745
8746
8747
8748
8749
8750
8751
8752
8753
8754
8755
8756
8757
8758
8759
8760
8761
8762
8763
8764
8765
8766
8767
8768
PUBLIC RELEASE DRAFT
April 2024
Appendix F ENVIRONMENTAL EXPOSURE DETAILS
F.l Ambient Air Measured Concentrations
This section provides a summary of the data used to build the ambient air measured scenarios to be used
to assess environmental concentrations and general population exposures to these releases. The
systematic review process identified studies that measured asbestos fibers in ambient air, FigureApx
F-l presents the concentration data per country, per asbestos analysis method, and per year.
Overall measured concentrations of asbestos in ambient air with unit of f/cc, extracted from 34 sources,
are summarized in the bullets that follow; Figure Apx F-l supplemental information is provided in
TableApx F-l.
• AHERA concentrations ranged from not detected to 0.0022 f/cc from 98 samples collected
between 2010 and 2011 in one country (United States). Location types were categorized as
General Population. Reported detection frequency was 0.2.
• Berman-Crump ranged concentrations ranged from not detected to 0.011 f/cc from 98 samples
collected between 2010 and 2011 in one country (United States). Location types were
categorized as General Population. Reported detection frequency was 0.2.
• EDS concentrations ranged from not detected to 0.0006 f/cc from 50 samples collected between
2014 and 2016 in one country (Italy). Location types were categorized as General Population and
Near Facility. Reported detection frequency ranged from 0.42 to 0.5.
• N/R concentrations were not detected f/cc from six samples collected in 1997 in one country,
(United States). Location types were categorized as General Population. Reported detection
frequency was 0.0.
• PCM concentrations ranged from not detected to 90.0 f/cc from 7,333 samples collected between
1982 and 2021 in 4 countries (Canada, Korea, Poland, and United States). Location types were
categorized as General Population, Unknown/Not Specified, Consumer Use and Near Facility.
Reported detection frequency ranged from 0.0 to 1.0.
• PCME concentrations ranged from not detected to 0.012 f/cc from 637 samples collected
between 1989 and 2021 in 3 countries (Japan, Korea, and United States). Location types were
categorized as Remote, General Population, Near Facility and Take-Home. Reported detection
frequency was not reported.
• PLM concentrations were 0.0002 f/cc from 97 samples collected in 2014 in one country (United
States). Location types were categorized as Near Facility. Reported detection frequency was
0.11.
• SEM concentrations ranged from not detected to 0.63 f/cc from 36 samples collected between
1991 and 2012 in 3 countries (Israel, Italy, and United States). Location types were categorized
as General Population and Near Facility. Reported detection frequency was 1.0.
• TEM concentrations ranged from not detected to 1,200.0 f/cc from 3,843 samples collected
between 1977 and 2021 in 7 countries (Canada, Switzerland, France, Great Britain, Japan,
Korea, and United States). Location types were categorized as Remote, General Population and
Near Facility. Reported detection frequency ranged from 0.0 to 1.0.
Page 319 of 405
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April 2024
8769
8770
HII General Population
Near Facility
Consumer Use
| Unknown/Not Specified
US -AHERA
g; Non-Dctect
3970353 - ATSDR, 2015 - US*
1
US - Berman-Crump
3970353 - ATSDR, 2015 - US*
1
NonUS - EDS
6865650 - Capella, et al., 2020 - IT
1
3361883 - Turci, et al., 2016 - IT
US-NR
10284987 - ATSDR, 2002 - US
*
US - PCM
783704 - U.S, 2000 - US*
2604770 - Lange, et al., 2008 - US*
«
1079550 - Perkins, et al., 2007 - US
•
1079550 - Perkins, et al., 2007 - US
6878182 - Lee, et al., 1999 - US
II
7481806 - Dusek and Yetman, 1993 - US
3970154-U.S, 1991 - US
6892380-U.S, 1986-US
•
3531143 - Mangold, et al., 2006 - US
«
NonUS-PCM
2592915 - Krakowiak, et al., 2009 - PL
1
2592915 - Krakowiak, et al.. 2009 - PL
1
NonUS - PCM
7482446 - Jung, et al., 2021 - KR
6908584 - Yoon, et al., 2020 - KR
3077896 - Buczaj, et al., 2014 - PL
3077896 - Buczaj, et al., 2014 - PL
IM
2567822 - Szeszenia-D browska, et al., 2012 - PL
524413 - Stefani, et al., 2005 - CA
524413 - Stefani, et al., 2005 - CA
10A-6 10A-4 0.01
100 I0A4
Concentration (f/cc) (pt 1)
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April 2024
8771 (continued)
fSIs General Population
IBHI Near Facility
Take-Home
I Remote
US - PCME
81 Non-Detect
6865897 - Neitzel, et alM 2020 - US*
3970353 - ATSDR, 2015 - US*
NonUS - PCME
7482446 - Jung, et al., 2021 - KR
14 - Kohyama, Ed. 1989-JP
*
14 - Kohyama, Ed. 1989-JP
•
14- Kohyama, Ed. 1989-JP
*
US - PLM
3970087 - CDM Federal Programs Corporation, 2014 - US*
1
US - SEM
6906546 - Baxter, et al., 1983 - US
NonUS - SEM
2567890 - Cattaneo. et al., 2012 - IT
3096697 - Ganor, et al., 1992 - IL
1
3096697 - Ganor, et al., 1992 - IL
1
US - TEM
2568686 - Lee, et al., 2009 - US
3970353 - ATSDR, 2015 - US*
2551667 - Ryan, et al., 2015 - US
6906546 - Baxter, et al., 1983 - US
6906546 - Baxter, et al., 1983 - US
6874316 - Nolan and Langer, Eds., 2001 - US*
¦
2603705 - Axten and Foster, 2008 - US
6878182 - Lee, et al., 1999 - US
1079550 - Perkins, et al., 2007 - US
1
3970154-U.S, 1991 - US
1
6892380-U.S, 1986-US
¦
NonUS - TEM
7482446 - Jung, et al., 2021 - KR
733573 - Lim, et al., 2004 - KR
•
10M> 10M 0.01
100 I0A4
Concentration (f/cc) (pt 2)
8773
Page 321 of 405
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8774 (continued)
PUBLIC RELEASE DRAFT
April 2024
NonUS-TEM
Mix - TEM
524413 - Stefani, et al., 2005 - CA
524413 - Stefani, et al., 2005 - CA
3531405 - Sakai, et al., 2001 - JP
3531405 - Sakai, et al., 2001 - JP
3081847 - Dong, et al., 1994 - FR
3582281 - Jaffrey, 1990 - GB
6862009 - Litzistorf, et al., 1985 - CH
6862009 - Litzistorf, et al., 1985 - CH I
6862009 - Litzistorf, et al., 1985 - CH I
3978368 - CAREX Canada. 2017, - CA,US
10A-6
General Population
| Near Facility
Remote
Non-Detect
10A-4
0.01 1
Concentration (f/cc) (pt 3)
100
10A4
FigureApx F-l. Concentrations of Asbestos (f/cc) in Ambient Air from 1977 to 2021
* = Reference used in draft risk evaluation
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Table Apx F-l. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in Ambient Air
Citation
Fiber Type(s)
Fiber Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit (f/cc)
Overall Quality
Level
AHERA
(ATSDR. 2015) a
Chrysotile (asbestifonn of
mineral serpentine)
N/R
US
General
Population
2010-2011
98 (0.20)
N/R
Medium
Berman-Crump
(ATSDR. 2015) a
Chrysotile (asbestifonn of
mineral serpentine)
N/R
US
General
Population
2010-2011
98 (0.20)
N/R
Medium
EDS
(Caoclla et al.. 2020)
Tremolite; actinolite
>5 (im
IT
General
Population
2014-2016
48 (0.42)
N/R
Medium
(Turci et al.. 2016)
Chrysotile (asbestifonn of
mineral serpentine)
0.8 nm
IT
Near Facility
2016
2 (0.50)
N/R
Medium
N/R
(ATSDR. 2002)
General
N/R
US
General
Population
1997
6 (0.00)
0.0846
Medium
PCM
(U.S. EPA. 2000a)a
General
>5^m
us
Consumer
Use
2000
7 (1.00)
N/R
Medium
(Lanse et al.. 2008)
General
0.8 |im
us
Near Facility
2000
248 (N/R)
0.1
Medium
(Perkins et al.. 2007)
General
N/R
us
General
Population
1999
3 (0.00)
0.001
Medium
(Perkins et al.. 2007)
General
N/R
us
Near Facility
1994-1999
24 (0.67)
0.003
Medium
(Lee et al.. 1999)
General
>5 nm
us
General
Population
1998
590 (N/R)
N/R
Medium
(Dusek and Yetman
1993)
General
Tremolite
Actinolite
N/R
us
General
Population
1989-1990
12 (N/R)
N/R
Medium
(U.S. EPA. 1991)
Chrysotile (asbestifonn of
mineral serpentine)
>5^m
us
Near Facility
1986-1987
8 (0.50)
N/R
Medium
(U.S. EPA. 1986b)
General
>0.8 |im
us
General
Population
1984-1985
5 (0.00)
0.002
High
(Mansold et al..
2006)
Chrysotile (asbestifonn of
mineral serpentine)
> 5|im length
us
Consumer
Use
1982
12 (N/R)
0.004
Medium
(Krakowiak et al..
2009)
Chrysotile
N/R
PL
General
Population
2009
59 (N/R)
0.001
Medium
(Krakowiak et al..
2009)
Chrysotile
N/R
PL
Near Facility
2009
82 (N/R)
N/R
Medium
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Citation
Fiber Type(s)
Fiber Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit (f/cc)
Overall Quality
Level
(June et al.. 2021)
Chrysotile (asbestifomi of
mineral serpentine)
Tremolite
Cctinolite
5.24-35.5 urn
5.01-28.5 nm
6.07^10.2 nm
KR
General
Population
2021
125 (N/R)
N/R
Medium
(Yoon et al.. 2020)
General
Chrysotile (asbestifonn of
mineral serpentine)
Tremolite
Actinolite
N/R
KR
Near Facility
2020
87 (0.31)
N/R
Low
(Buczai et al.. 2014)
General
0.8 (im
PL
General
Population
2009-2011
21 (0.33)
N/R
Medium
(Buczai et al.. 2014)
General
1
00
©
PL
Near Facility
2009-2011
66 (0.82)
N/R
Medium
(Szeszenia-
Dabrowska et al..
2012)
General
>5 (im
PL
Unknown/
Not Specified
2004-2010
5,962 (0.98)
180.0
Medium
(Stefani et al.. 2005)
General
N/R
CA
General
Population
1998
9 (0.22)
0.001
Low
(Stefani et al.. 2005)
General
N/R
CA
Near Facility
1998
13 (0.77)
0.006
Low
PCME
(Ncitzcl et al..
2020)*
Chrysotile (asbestifonn of
mineral serpentine)
10-20 |im
US
Take-Home
2017-2018
25 (N/R)
N/R
Medium
(ATSDR. 2015)*
General
Chrysotile (asbestifonn of
mineral serpentine)
N/R
US
General
Population
2008-2011
149 (N/R)
N/R
Medium
(June et al.. 2021)
Chrysotile (asbestifonn of
mineral serpentine)
Tremolite
Actinolite
5.24-35.5 |im.
5.01-28.5 nm,
6.07^10.2 nm
KR
General
Population
2021
227 (N/R)
N/R
Medium
(Kohvama. 1989)
Chrysotile (asbestifonn of
mineral serpentine)
>5 nm
JP
General
Population
1989
96 (N/R)
0.02
Medium
(Kohvama. 1989)
Chrysotile (asbestifonn of
mineral serpentine)
Amosite (asbestifonn of
mineral grunerite)
>5 nm
JP
Near Facility
1989
102 (N/R)
0.02
Medium
(Kohvama. 1989)
Chrysotile (asbestifonn of
mineral serpentine)
>5 nm
JP
Remote
1989
38 (N/R)
0.02
Medium
PLM
(CDM Federal
Proerams
General
Tremolite
N/R
US
Near Facility
2014
97 (0.11)
N/R
Medium
Corporation. 2014)*
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Citation
Fiber Type(s)
Fiber Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit (f/cc)
Overall Quality
Level
SEM
(Baxter et al.. 1983)
Chrysotile (asbestifonn of
mineral serpentine)
>5^m
US
Near Facility
2001
6 (1.00)
2400.0
Medium
(Cattanco et al..
2012)
Chrysotile (asbestifonn of
mineral serpentine)
8.1 nm
IT
Near Facility
2012
22 (N/R)
N/R
Medium
(Ganor et al.. 1992)
Crocidolite (asbestifonn of
mineral riebeckite)
N/R
IL
General
Population
1991
4 (N/R)
N/R
Medium
(Ganor et al.. 1992)
Crocidolite (asbestifonn of
mineral riebeckite)
N/R
IL
Near Facility
1991
4 (N/R)
N/R
Medium
TEM
(Lee et al.. 2009)
General
Crocidolite (asbestifonn of
mineral riebeckite)
Amosite (asbestifonn of
mineral grunerite)
Tremolite
Actinolite
>5 nm
US
Near Facility
2019
122 (N/R)
N/R
Medium
(ATSDR. 2015)*
General
Chrysotile (asbestifonn of
mineral serpentine)
N/R
US
General
Population
2008-2011
149 (N/R)
N/R
Medium
(Rvan et al.. 2015)
General
>5um
us
Near Facility
2007-2008
186 (N/R)
N/R
High
(Baxter et al.. 1983)
Chrysotile (asbestifonn of
mineral serpentine)
>5^m
us
General
Population
2001
38 (0.55)
2,400.0
Medium
(Baxter et al.. 1983)
Chrysotile (asbestifonn of
mineral serpentine)
>5^m
us
Near Facility
2001
22 (0.73)
2,400.0
Medium
(Nolan and Lanser.
2001)*
General
Chrysotile (asbestifonn of
mineral serpentine)
Amosite (asbestifonn of
mineral grunerite)
>5 (im
us
General
Population
2001
40 (N/R)
N/R
Medium
(Axten and Foster.
2008)
Tremolite
Actinolite
N/R
us
Near Facility
1990-1998
380 (N/R)
N/R
Medium
(Lee et al.. 1999)
General
>5 nm
us
General
Population
1998
590 (N/R)
N/R
Medium
(Perkins et al.. 2007)
General
N/R
us
Near Facility
1994
9 (0.22)
N/R
Medium
(U.S. EPA. 1991)
Chrysotile (asbestifonn of
mineral serpentine)
>5 nm
us
Near Facility
1986
4 (0.75)
N/R
Medium
(U.S. EPA. 1986b)
General
>0.4 nm
us
General
Population
1984-1985
2 (0.50)
0.006
High
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Citation
Fiber Type(s)
Fiber Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit (f/cc)
Overall Quality
Level
(June et al.. 2021)
Chrysotile (asbestiform of
mineral serpentine)
Tremolite
Actinolite
5.24-35.5 urn,
5.01-28.5 nm,
6.07^10.2 nm
KR
General
Population
2021
352 (N/R)
N/R
Medium
(Lim et al.. 2004)
Chrysotile (asbestiform of
mineral serpentine)
Amosite (asbestiform of
mineral grunerite)
Tremolite
Actinolite
Chrysotile (asbestiform of
mineral serpentine)
Amosite (asbestiform of
mineral grunerite)
Actinolite
Tremolite
Crocidolite (asbestiform of
mineral riebeckite)
Anthophyllite
0.2 nm
N/R
KR
General
Population
2001
96 (N/R)
0.00029
Medium
(Stefani et al.. 2005)
General
N/R
CA
General
Population
1998
4 (0.00)
0.001
Low
(Stefani et al.. 2005)
General
N/R
CA
Near Facility
1998
4 (0.75)
0.0003
Low
(Sakai et al.. 2001)
General
Chrysotile (asbestiform of
mineral serpentine)
Tremolite
Actinolite
Crocidolite (asbestiform of
mineral riebeckite)
Amosite (asbestiform of
mineral grunerite)
Anthophyllite
>2|im
JP
General
Population
1996
2 (0.00)
0.002
Medium
(Sakai et al.. 2001)
General Chrysotile
(asbestiform of mineral
serpentine)
Tremolite
Actinolite
Crocidolite (asbestiform of
mineral riebeckite)
>2|im
JP
Near Facility
1996
14 (0.79)
0.002
Medium
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Citation
Fiber Type(s)
Fiber Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit (f/cc)
Overall Quality
Level
Amosite (asbestifonn of
mineral grunerite)
Anthophyllite
(Doneetal.. 1994)
General Chrysotile
(asbestifonn of mineral
serpentine)
>5^m
>0.5|im
FR
General
Population
1993
2 (0.50)
N/R
Medium
(laffrev. 1990)
General
N/R
GB
General
Population
1990
50 (0.34)
N/R
Medium
(Litzistorf et al..
1985)
Chrysotile (asbestifonn of
mineral serpentine)
All sizes
CH
General
Population
1977-1983
12 (1.00)
N/R
Medium
(Litzistorf et al..
1985)
Chrysotile (asbestifonn of
mineral serpentine)
All sizes
CH
Remote
1983
2 (1.00)
N/R
Medium
(Litzistorf et al..
1985)
Chrysotile (asbestifonn of
mineral serpentine)
All sizes
CH
Near Facility
1981-1982
4 (1.00)
N/R
Medium
(Carex Canada.
2017)
General
N/R
CA, US
General
Population
2011
1,759 (N/R)
N/R
Medium
" Used in draft risk evaluation
N/R = not reported; CA = Canada; CH = Switzerland; FR = France; GB = Greece; IT = Italy; IP = lapan; KR = Korea; PL = Poland; US = United States
8780
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Overall measured concentrations of Asbestos in Ambient Air with unit of s/cc, extracted from 11
sources, are summarized in the bullets that follow and presented in FigureApx F-2. Additional
information is provided in Table Apx F-2.
• Concentrations for SEM ranged from not detected to 924.0 s/cc from 10 samples collected
between 1975 and 1976 in 1 country, Russia. Location types were categorized as Near Facility.
Reported detection frequency was 0.9.
• Concentrations for TEM ranged from not detected to 6.3 s/cc from 3,867 samples collected
between 1987 and 2008 in 1 country (United States). Location types were categorized as General
Population, Unknown/Not Specified and Near Facility. Reported detection frequency ranged
from 0.0 to 1.0.
• Concentrations for TEM, PLM ranged from 1 x 10~5 to 0.00039 s/cc from 48 samples collected in
1988 in 1 country (United States). Location types were categorized as General Population.
Reported detection frequency was not reported.
¦¦¦ General Population
Near Facility
| Unknown/Not Specified
US - TEM. PLM
a Non-Detect
6912224 - Hatfield, et al., 1988 - US
US - TEM
2604527 - Lee and Van Orden, 2008 - US*
3969298 - John, 2004 - US*
3982256 - DTSC, 2005 - US*
3982256 - DTSC, 2005 - US*
3097354 - Reynolds, et al., 1994 - US
•
3970150 - Corporation, 1993 - US
3714772 - Corn, et al., 1991 - US
3970146-U.S, 1993-US
3970150 - Corporation, 1993 - US
¦
6900979 - Kominsky, et al., 1989 - US
3095922 - Chesson, et al., 1990 - US
NonUS - SEM
3082917 - Milosevi and Petrovi, 1988 - RS
1(^-5 10A-4 0.001 0.01 0
1 1 10 100 1000
Concentration (s/cc)
Figure Apx F-2. Concentrations of Asbestos (s/cc) in Ambient Air from 1975 to 2008
* = Reference used in risk determination
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8799 TableApx F-2. Summary of Peer-Reviewed Literature that Measured Asbestos (s/cc) Levels in
8800 Ambient Air
Source
Fiber Type(s)
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit
(s/cc)
Overall
Quality
Level
SEM
(Milosevic
and Petrovic.
1988)
General
<7 |im
RS
Near
Facility
1975-1976
10 (0.90)
N/R
Low
TEM
(Lee and Van
Orden. 2008)
a
General
N/R
US
Near
Facility
2008
3356 (N/R)
N/R
Medium
(John. 2004) °
Chrysotile
(asbestifonn
of mineral
serpentine)
both <5
|im and
>5 nm
us
General
Population
2002-2003
68 (N/R)
N/R
Medium
(DTSC. 2005)
a
General
>5 |im
us
General
Population
2002-2003
1 (1.00)
N/R
High
(DTSC. 2005)
a
General
>5 |im
us
Near
Facility
2002-2003
29 (N/R)
N/R
High
(Reynolds et
al.. 1994)
General
>0.5 |im
us
Near
Facility
1994
6 (0.00)
0.002
Medium
(IT
Corporation.
1993)
General
Chrysotile
(asbestifonn
of mineral
serpentine)
Chrysotile
(asbestifonn
of mineral
serpentine)
Amosite
(asbestifonn
of mineral
grunerite)
0.45 nm
us
Near
Facility
1989-1993
156 (N/R)
N/R
Low
(Cornet al..
1991)
General
0.8-1.2
Hin; 0.4
Hin
us
General
Population
1991
94 (N/R)
N/R
Medium
(U.S. EPA.
1993)
General
N/R
us
Unknown/
Not
Specified
1991
75 (N/R)
N/R
High
(IT
Coroo ration.
1993)
General
Chrysotile
(asbestifonn
of mineral
serpentine)
0.45 nm
us
General
Population
1989
33 (N/R)
N/R
Low
(Kominskv et
al.. 1989)
General
N/R
us
Near
Facility
1989
12 (N/R)
N/R
Medium
(Chesson et
al.. 1990)
General
N/R
us
Near
Facility
1987
37 (N/R)
N/R
Medium
TEM, PLM
(Hatfield et
al.. 1988)
General
1 |im
us
General
Population
1988
48 (N/R)
N/R
Medium
" Used in this draft risk evaluation.
N/R = not reported; RS = Russia; US = United States
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Table 3-9 in Section 3.3.1 is an abbreviated version of Table Apx F-3 below, which includes details on
the source of the data, the statistics performed to obtain the low-, high-end, and central tendencies.
Table Apx F-3. Summary of Published Literature for Measured Ambient Air Concentrations
Proposed
Scenario
Source Description
Reported Concentration (f/cc)
Summary Stats Per Proposed
Scenario (f/cc)
Value
(f/cc)
Stat Type and
Description
LE
HE
CT
Near Facility or
Near Source
gardening
products
(U.S. EPA. 2000a)
Location: Springfield, VA
Sampling Date: 2000 (implied
from publishing date)
Rating: High
0.011
Min - source reported
0.011
Reported
min
0.00957
Reported
max
0.01029
Averaged
LE and HE
0.00957
Max - source reported
Near Facility or
Near Source
public space
urban
(Lanse et al.. 2008)
Location: Eastern US
Sampling Date: 2000
Rating: Medium
0.01
0.01
0.01
0.01
0.01
Min - source reported
DL, multiple samples
of 5 types of products
removed. All BDL
0.00307
10th
percentile
all reported
data
0.0202
95th
percentile
all reported
data
0.01053
Averaged
all reported
data
0.03
0.02
0.02
0.02
0.02
Max - source reported,
multiple samples of 5
types of products
removed.
0.01
0.01
0.01
0.01
0.01
Average - source
reported DL, multiple
samples of 5 types of
products removed. All
BDL
(Neitzel et al.. 2020)
Location: Detroit, MI
Sampling Date: 2017
Rating: Medium
0.0001
90th percentile -
source reported, only
value above DL
Near facility or
near source
public space
urban
(Nolan and Lanser. 2001)
0.00201
Average - source
reported from 9
samples at various
schools
0.00104
10th
percentile
all reported
data
0.0022
95th
percentile
all reported
data
0.00168
Averaged
all reported
data
Location: Various U.S.
Sampling Date: 2001
Rating: Medium
0.0008
Data point - source
reported from a school
0.00222
Average - source
reported from 31
samples at various
universities
Perimeter
industrial
location
(ATSDR 2015)
Location: Ambler,
Montgomery County,
Pennsylvania, BoRit Site
Sampling Date: 2008 and 2010
Rating Medium
0.0003
Min - source reported
from 51 samples in
2008, all other samples
were BDL
0.0015
10th
percentile
all reported
data
0.009
95th
percentile
all reported
data
0.0053
Averaged
all reported
data
0.0006
0.012
0.001
0.0022
0.023
0.011
Max - source reported
from 51 samples in
2008 and 98 in 2010
LE = low-end, HE = high-end; CT = central tendency
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F.2 Ambient Air Modeled Concentrations
This section describes in detail the methodologies utilized to estimate ambient air concentrations and
exposures for members of the general population that are in proximity (between 10 to 10,000 m) to
emissions sources emitting asbestos fibers. All exposures were assessed for the inhalation route only.
The overall steps to obtain ambient air exposure concentrations and risk calculations are provided
below:
• Step 1: Obtain TRI and NEI data
• Step 2: Map TRI and NEI data to OESs
• Step 3: Estimate the number of releases days for each OES
• Step 4: Estimate air emissions for OES with no TRI or NEI data
• Step 5: Prepare air emission summary for ambient air exposure modeling, see Air Release
Assessment for Legacy Asbestos 3.27.2023. xlsx
• Step 6: Specific facilities - EPA modeled exposure concentrations on a facility-by-facility basis,
building out a series of facility specific exposure scenarios based on the release data provided by
Steps 1 to 5. EPA modeled exposure concentrations at eight finite distances from a releasing
facility (10, 30, 60, 100, 1,000 2,500, 5,000 and 10,000 m) in a series of concentric rings around
the facility
• Step 7: Generic facilities - Represent additional unknown facilities, EPA developed generic TRI
facilities with ranges of emission rates
• Step 8: Estimate air concentrations and deposition resulting from air releases of asbestos,
modeled at general-population and co-located exposure points surrounding the release sources
using AERMOD
TRI and NEI emission data are for specific facilities provided actual geographical coordinates and
description of asbestos releases activities. Because activities that release asbestos can be transitory, for
example demolition of structures and removal of asbestos containing materials, and firefighting
activities the word facilities in this RE can apply to stationary and permanent locations as well as
temporary. EPA developed scenarios for TRI facilities with ranges of emission rates for unknown and
transitory activities and are referred to as "generic facilities."
EPA modeled exposure concentrations on a facility-by-facility basis (specific and generic facilities),
building out a series of facility-specific exposure scenarios based on the release data provided in
Appendix E.16.3. EPA modeled exposure concentrations at eight points at finite distances from a
releasing facility (10, 30, 60, 100, 1,000, 2,500, 5,000 and 10,000 m) in a series of concentric rings
around the facility. All modeling scenarios utilized a region of gridded exposure points and several
rings/radials of exposure points. The rings had exposure points placed every 22.5 degrees (starting due
north of the facility) for distances 10, 30, and 60 m from the source for co-located exposure points and
100, 1,000, 2,500, 5,000, and 10,000 m from the source for general-population exposure points.
Between 100 m and 1,000 m from the source—an area termed "community" in IIOAC. All exposure
points were at 1.8 m above ground, as a proxy for breathing height for concentration estimates. A
duplicate set of exposure points was at ground level (0 m) for deposition estimations.
Facility coordinates, in the form of latitude/longitude coordinates, were mapped (Figure Apx F-3) to
show locations by OES and used to match the facility to the closest available meteorological station.
Latitude/longitude coordinates were extracted from TRI and provided as part of the release assessment
for facilities reporting to the 2019 TRI. NEI facilities did not have coordinates.
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WASHINGTON
OREGON
NORTH DAKOTA
MINNESOTA
SOUTH DAJCOTA
UNITED STATES
DLORADO KANSAS
n
OttaW3
JjT
OHIO
DIANA W£5
N J.
• •
A^fORNlA •
MO
VIRGINIA
NTUCKY VIRGINIA
ESSEE
NC
NEW MEXICO
V
TEXAS
\
E
, Burbank^-v
T-^'tGleg^alc j®
'j ^ J Rft y
Losfclhgele#* "ei Monte
¦I \ Florence , m. —-
•glewood fell T
Hiwtbfr# ^^pj^-fX^Fulley
^ grange
LongE*»clf ^ , Santa Ana
R»ncho P*to> M,j
Verde* '"" V," >.
Huntington Beach
m'T - &
San Bernardino
#edl«ndi
Riverside
^/'Moreno Valley
V
of M#*lco
• • °
-o
Channelview*
Houston - •
Baytown
ST." - Pasadena "^
_ Sugar Land — \
0 Pearland
La Porte
League City
Dickinson
Alvin
Texas City
Galv
Angleton
«"y Lake Jackson
0 Handling Articles or Formulations that Contain Asbestos
C* Handling Asbestos-Containing Building Materials During Maintenance, Renovation, and Demolition Activities
Q Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery Containing Asbestos
C? Waste Handling, Disposal, and Treatment
Figure Apx F-3. Map of Specific Facilities by OES
More parameters were required to run the higher tier model, AERMOD. EPA reviewed available
literature to select input parameters for deposition, particle sizes, meteorological data, urban/rural
designations, and physical source specifications. A full description of the input parameters selected for
AERMOD and details regarding post-processing of the results are provided in Appendices F.2.1 to F.2.9
below.
F.2.1 Meteorological Data
Specific facilities meteorological data used in AERMOD the same meteorological data that EPA's Risk
and Technology Review (RTR) program uses for risk modeling in review of National Emission
Standards for Hazardous Air Pollutants (NESHAP). The RTR data cover hourly stations in the 50 states,
District of Columbia, and Puerto Rico. The meteorological data set that the RTR program currently uses
includes 838 stations with data mostly from the year 2019 for 47 stations (mainly in Alaska and West
Virginia). EPA utilized data from 2016, 2017, or 2018 to fill notable spatial gaps. The RTR 2019
meteorological data set was used to model emission years 2018 and 2019. Meteorological data from
2016 was used for emission years 2014 to 2017, covering 824 stations, which the RTR program used
prior to the updates to the 2019 data set.
Generic facilities meteorological data was modeled twice with two different meteorological stations.
EPA's IIO AC utilized a meteorological station for each region of the countiy and from this data set it
was determined that meteorological conditions from Sioux Falls, South Dakota, led to central tendency
modeled concentrations and particle deposition, and those from Lake Charles, Louisiana, led to high-end
modeled concentrations, relative to the other regional stations (see Sections 5.4 and 5.7.4 of the IIO AC
User Guide for more information on the stations.
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F.2.2 Urban and Rural Populations
Urban/rural designations of the area around a facility are relevant when considering possible boundary
layer effects on concentrations. Air emissions taking place in an urbanized area are subject to the effects
of urban heat islands, particularly at night. When sources are set as urban in AERMOD, the model will
modify the boundary layer to enhance nighttime turbulence, often leading to higher nighttime air
concentrations. AERMOD uses urban-area population as a proxy for the intensity of this effect.
Facilities were not set as urban unless they met one of the EPA-recommended definitions of an urban
area—specifically, the Agency considered a facility to be in an urban area if it had a population density
greater than 750 people per square km within a 3 km radius. Generic facilities were modeled for both
rural and urban populations for the applicable OES.
F.2.3 Source Specifications
The TRI facilities modeling assumed all emissions were centered on one location. EPA set the same
default physical parameters as in IIOAC, stack emissions released from a point source at 10 m above
ground from a 2-meter inside diameter, with an exit gas temperature of 300 °K and an exit gas velocity
of 5 m/s (see Table 6 of the IIOAC User Guide), and fugitive emissions released at 3.05 m above ground
from a square area source 10 m on a side (see Table 7 of the IIOAC User Guide).
The NEI modeling also assumed all emissions were centered on one location. When the site-specific
parameter values were available, EPA utilized these in the modeling as done for TRI facilities. When
parameters were not available or had values outside of normal bounds, EPA replaced the values based
on the procedures used in AirToxScreen (see Section 2.1.3 of EPA, 2018 AirToxScreen Technical
Support Document).
• There were 89 fugitive sources with quantifiable emissions.
o Zero sources had release heights and 3 sources had values of length and width that were
above zero.
o A fugitive height of 3.048 m to all 89 fugitive sources was used; 3 sources provided
length, width, and angle values, and a value of 10 m was used for the fugitive length and
width (and 0 degrees for fugitive angle) for the other 86 sources.
• There were 15 stack sources with quantifiable emissions. Source classification codes (SCCs)
were not provided.
o One source had values of zero for all physical stack parameters. The values with global
default values were replaced (height = 3 m, inside diameter = 0.2 m, exit gas temperature
= 295.4 °K; exit gas velocity = 4 m/s).
o One additional source had a value of zero for exit gas velocity with values above zero for
inside diameter and exit gas flow rate. The velocity was calculated using the diameter and
flow values (Table Apx F-4). This source had in-bounds values for the other parameters,
o All other sources had in-bounds values for all physical stack parameters and were used
for modeling.
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TableApx F-4. Procedures for Replacing Values of Physical Source Parameters from the
National Emissions Inventory
Condition
Missing Value or Zero
Parameters
Bounds
First Pass
Second Pass
(When First Pass
Unsuccessful)
Third Pass
(When First and
Second Passes
Unsuccessful)
Value Is out of
Normal Bounds
Stack height
1-1300 ft
Use default value
Use global
N/A
Use the minimum
(0.3048-396 m)
by SCC (pstk file)
default: 3 m
in-bound value
Stack inside
0.001-300 ft
Use default value
Use global
N/A
Use the minimum
diameter
(0.0003048-91.4 m)
by SCC (pstk file)
default: 0.2 m
in-bound value
Stack exit gas
>0-4000 °F
Use default value
Use global
N/A
Use the minimum
temperature"
(>255.4-2477.6 °K)
by SCC (pstk file)
default: 295.4 °K
in-bound value
Stack exit gas
0.001-1000 ft/s
Calculate from
Use default value
Use global
Use the minimum
velocity
(0.0003048-304.8
m/s)
existing exit gas
flow rate and
inside diameter:
(4 x flow) / (jt x
diameter2)
by SCC (pstk file)
default: 4 m/s
in-bound value
Fugitive height
N/A
0 m if length and
width are not
missing and are
above 0; 3.048 m
if length or width
are missing or 0
N/A
N/A
N/A
Fugitive length
N/A
10 m
N/A
N/A
N/A
Fugitive width
N/A
10 m
N/A
N/A
N/A
Fugitive angle
N/A
0 deg
N/A
N/A
N/A
" For exit gas temperatures, EPA modified AirToxScreen's value bounds so that values must be above 0
°F.
pstk file = file of default stack parameters by source classification code (SCC) from EPA's SMOKE emissions kernel:
ostk 13nov2018 vl.txt. retrieved on 28 September 2022 from httt>s://cmascenter.ore/smoke/.
F.2.4 Temporal Emission Patterns
The Air Release Assessment for Legacy Asbestos spreadsheet available in the occupational exposure
assessment (Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure Data Tables
- Fall 2023 (U.S. EPA. 2023i) (see Appendix C) contain information on temporal emission patterns such
as release duration (across the hours of a day, or intraday) and release pattern (across the days of a year,
or interday), by OES. The hours shown conform to AERMOD's notation scheme of using hours 1 to 24,
where hour 1 is the hour ending at 1 a.m. and hour 24 is the final hour of the same day ending at
midnight. EPA assumed that emissions took place every day of the year, and then turned emissions off
for certain days of the year as needed to achieve the desired number of emission days, such as no
emissions on Saturday and Sunday, and major holidays. Table Apx F-5 summarizes assumptions used
for intraday release duration and Table Apx F-6 summaries assumptions used for interday release
patterns.
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Table Apx F-5. Assumptions for Intraday Emission-Release Duration Used in AERMOD
Hours per Day
of Emissions
Assumed Hours of the Day Emitting (Inclusive)
4
Hours 13-16 (hour ending at 1 p.m. through hour ending at 4 p.m.; i.e., 12-4 p.m.)
8
Hours 9-16 (hour ending at 9 a.m. through hour ending at 4 p.m.; i.e., 8 a.m. to 4 p.m.)
Table Apx F-6. Assumptions for Interday Emission-Release Pattern Used in AERMOD
Provided Language for Release Pattern
Implemented Release Pattern: Days When
Emissions Are On
Release pattern: 250 days/year based on the assumption
of operations over 5 days/week and 50 weeks/year
All Mondays through Fridays, except 1/1-1/4 and
12/21—12/31 (and 1/5 for years 2012, 2016, and 2020)
Release pattern: 12 days/year based on results of
literature search
The first day of each month
Release pattern: 1 day/year based on results of literature
search
2/1
Note that some of the "Provided Language for Release Pattern" is specific to an OES.
F.2.5 Emission Rates
The Air Release Assessment for Legacy Asbestos spreadsheet available in the occupational exposure
assessment (Asbestos Part 2 Draft RE - Environmental Release and Occupational Exposure Data Tables
- Fall 2023) (U.S. EPA. 2023i) (see also Appendix C) contain emission rates (kg/yr) for each facility,
total fugitive emissions, and total stack emissions. A central tendency value and a high-end value was
provided for generic TRI facilities and was used to obtain total fugitive and stack emissions. EPA
modeled lower- and higher-end emission scenarios separately. The rates were converted to grams per
second (g/s) for stack sources and grams per second per m2 for fugitive sources. The conversion from
per-hour to per-second utilized the number of emitting hours per year based on the assumed temporal
release patterns, and the conversion to per m2 for fugitive sources utilized the final length and width
values decided based on the procedures by the physical specifications.
F.2.6 Deposition Parameters
EPA used methodl option in AERMOD, which is recommended when the particle-size distribution is
well known or when at least 10 percent of particles (by mass) are 10 |im or larger. Asbestos fibers are
not spheres and AERMOD assumes spheres in the deposition calculations that affect settling velocity.
EPA calculated the potential sphericity of asbestos particles. The average diameter, aspect ratio, and
percent by size bin in Table 3 of Wilson et al. (2008) provided a particle size distribution guideline and
it was assumed fibers are cylindrical to calculate fiber length (Equation 1) and volume fraction (mass
fraction). The settings for particle deposition modeling are summarized in Table Apx F-7. Fiber length
was calculated using EquationApx F-l:
EquationApx F-l.
Fiber Length = Diameter x Aspect Ratio
The fiber size was calculated using Equation Apx F-2:
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EquationApx F-2.
V
/ Diameter \ 3
Fihpv Si7P — I I
\Length x Diameter J
The equivalent spherical diameter of each size was calculated using Equation Apx F-3:
Equation Apx F-3.
V
/ /Length\ \ 2
Spherical Diameter = 2 x I Sphericity x I—-—) I
Table Apx F-7. Settings for Particle Deposition
Mass-Mean Aerodynamic
Diameter (fim)
Mass
Fraction
Density
(g/cm3)
Notes/Sources
2.6
0.02
3.3
Diameter and mass fraction: (Wilson et al.. 2008)
Table 3, Equations 1, 2 and 3.
Density: conservative setting, the high value of specific
gravity provided for crocidolite fibers from (Virta.
2004)
6.1
0.06
3.3
10.8
0.07
3.3
37.8
0.85
3.3
Exposure points All modeling scenarios utilized a region of gridded exposure points and several
rings/radials of exposure points. The rings had exposure points placed every 22.5 degrees (starting due
north of the facility) for distances 10, 30, and 60 m from the source for co-located general population
exposure points and 100, 1,000, 2,500, 5,000, and 10,000 m from the source for general-population
exposure points. Between 100 m and 1,000 m from the source—an area termed "community" in IIOAC.
All exposure points were at 1.8 m above ground, as a proxy for breathing height for concentration
estimates. A duplicate set of exposure points was at ground level (0 m) for deposition estimations.
F.2.7 Output
EPA converted AERMOD concentration output units of micrograms (|ig) per m3 to fibers per cubic
centimeter (cm3), using the "European Community Directive 72/217/EEC" conversion factor in (Dodic-
Fikfak. 2007). specifically 0.1 mg/m3 = 2 fibers/cm3, or 1 |ig/m3 = 0.02 fibers/cm3—one of the higher
and more conservative values cited in that study, but not the highest. That same conversion factor was
used to convert AERMOD deposition units of g/m2 to fibers/m2, specifically, 1 g per m2 = 2x 1010 fibers
per m2
AERMOD daily and annual outputs assumed flat terrain for all modeling scenarios. Daily- and period-
average outputs for every run, where the period was 1 year for real facilities and 5 years for generic TRI
facilities.
Percentile statistics for released concentrations for OESs Handling asbestos-containing building
materials during maintenance, renovation, and demolition activities as well as Handling asbestos-
containing building materials during firefighting or other disaster response activities both emit only a
small number of days per year, so more than 95 percent of the days of the year are not emitting (no
concentrations) and hence the 10th, 50th, and 95th percentile daily concentrations is zero (while the
average is >0).
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F.2.8 Specific Facilities Ambient Air Concentrations
This section summarizes specific facilities ambient air concentrations data by facility description. The
patterns presented in FigureApx F-4 through FigureApx F-7 further support Section 3.3.1.2 discussion
points. These figures show a wide range of asbestos concentrations among facilities of similar
descriptions at the same distance from the source ranging 2 to 3 orders of magnitude difference, which
means that grouping and averaging by facility description will not show the differences among similar
description facilities even under the same OES.
1.00E-02
1.00E-03
^ 1.00E-G4
o
o
g' 1.00E-05
S
g 1.00E-06
u
S3
O
^ 1.00E-07
<
| 1.00E-08
£
Q
^ 1.00E-09
1.00E-10
1.00E-11
¦ Petrochemical Manufacturing Fugitive ¦ Colleges, Universities, and Professional Schools Fugitive
¦ Aircraft Manufacturing Fugitive ¦ Space Research and Technology Fugitive
Figure Apx F-4. Ambient Air Concentrations for Facilities under the Handling Articles or
Formulations that Contain Asbestos OES
Co-located General Population
10 30 60
General Population
I
100 1000 2500 5000 10000
Distance from Source (m)
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1.00E+00
1.00E-01
1.00E-02
1.00E-03
1.00E-04
1.00E-05
1.00E-06
1.00E-07
1.00E-08
1.00E-09
1.00E-10
1.00E-1I
1.00E-12
1.00E-13
1.00E-14
Co-located General Population
General Population
100
1000
2500
5000
9006
9007
9008
9009
9010
9011
9012
9013
9014
¦ National Security Fugitive
¦ Colleges, Universities, and Professional Schools Fugitive
¦ Junior Colleges Fugitive
¦ Specialty (except Psychiatric and Substance Abuse) Hospitals Fugitive
¦ Space Research and Technology Fugitive
¦ Amusement and Theme Parks Fugitive
¦ Water Supply and Irrigation Systems Fugitive
¦ Steam and Air-Conditioning Supply Fugitive
¦ Correctional Institutions Fugitive
¦ Other General Government Support Fugitive
Distance from Source (m)
¦ HMO Medical Centers Fugitive
General Medical and Surgical Hospitals Fugitive
¦ Guided Missile and Space Vehicle Manufacturing Fugitive
¦ Fossil Fuel Electric Power Generation Fugitive
¦ Motion Picture and Video Production Fugitive
¦ Storage Battery Manufacturing Fugitive
¦ Cemeteries and Crematories Fugitive
¦ Freestanding Ambulatory Surgical and Emergency Centers Fugitive
¦ Dental Equipment and Supplies Manufacturing Fugitive
¦ Fabricated Pipe and Pipe Fitting Manufacturing Fugitive
FigureApx F-5. Ambient Air Concentrations for Facilities under Handling Asbestos-Containing
Building Materials During Maintenance, Renovation, and Demolition Activities OES
1.00E+00
1.00E-01
1.00E-02
1.00E-03
1.00E-04
1.00E-05
1.00E-06
1.00E-07
1.00E-08
1.00E-09
1.00E-10
1.00E-11
1.00E-I2
1.00E-13
1.00E-14
1.00E-15
Co-located General Population
60
General Population
It
r
I,
i.
100
1000
¦ Cement Manufacturing Fugitive
i Fossil Fuel Electric Power Generation Fugitive
I Other Electric Power Generation Fugitive
Distance from Source (m)
¦ Asphalt Paving Mixture and Block Manufacturing Fugitive
¦ Ready-Mix Concrete Manufacturing Fugitive
¦ Natural Gas Distribution Fugitive
¦ Petroleum Refineries Fugitive
¦ Petrochemical Manufacturing Fugitive
Figure Apx F-6. Ambient Air Concentrations for Facilities under Use, Repair, or Disposal of
Industrial and Commercial Appliances or Machinery Containing Asbestos OES
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1.00E-01
1.00E-02
1.00E-03
<£ 1.00E-04
1.00E-05
8
O
.'a 1.00E-06
1.00E-07
1.00E-08
1 .OOE-09
1.00E-10
Co-located General Population
10
30
60
General Population
100
1000
2500
5000 10000
Distance from Source (m)
¦ Hazardous Waste Treatment and Disposal Fugitive ¦ Solid Waste Landfill Fugitive ¦ Materials Recovery Facilities Fugitive
FigureApx F-7. Ambient Air Concentrations for Facilities under Waste Handling, Disposal, and
Treatment OES
The specific facilities range of asbestos ambient air concentrations is orders of magnitude within OES
and same distance from the source.
F.2.9 Generic Facilities Ambient Air Concentrations by OES
This section summarizes generic facilities ambient air concentrations data by OES by rural and urban
fugitive emissions. The patterns in the figures further support Section 3.3.1.2 Generic Facilities
discussion points. Figure Apx F-8, Figure Apx F-9, and Figure Apx F-10 show a wide range of
asbestos concentrations between fugitive emissions by distance from source ranging 5 to 6 orders of
magnitude difference close to the source and increasing distance away from the source.
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1.00E-02
1.00E-03
1.00E-04
1.00E-05
o
<3 1.00E-06
G
o
? 1.00E-07
a
-------
l.OOE-OI
1.00E-02
1.00E-03
1.00E-04
^ 1.00E-05
^ 1.00E-06
I
a 1.00E-07
o
s
U 1.00E-08
1.00E-09
l.OOE-lO
l.OOE-11
1.00E-12
903 6 ¦ CT Fugitive Emissions Rural HE Met ¦ CT Fugitive Emissions Urban HE Met ¦ CT Fugitive Emissions Rural CT Met ¦ CT Fugitive Emissions Urban CT Met
9037 FigureApx F-10. Generic Annual Ambient Air Concentrations Waste Handling, Disposal, and
9038 Treatment Fugitive Emissions
9039 F.3 Ambient Air Concentrations Summary
9040 This section summarizes how the measured and modeled asbestos air concentrations were grouped by
9041 OES to be used for human and environmental risk characterization. First the modeled ambient air
9042 concentrations per OES figures in Appendix F.2.8 and Appendix F.2.9 show the low-end, central
9043 tendency, and high-end summary tables per OES and grouping and averaging (when appropriate) in this
9044 section. Bolded text within the tables are the values used in the assessment, in some instances these were
9045 the only values available in others are the result of combining, not bolded text, specific and generic rural
9046 and urban emissions.
9047 F.3.1 Low-End Tendency Ambient Air Concentration Groupings and Summary Tables
9048
Table Apx F-8. Low-End Tendency Am
jient Air
Concentrations Summary by OES
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Use, repair, or disposal of industrial and commercial appliances or machinery containing asbestos
Grouping
Specific
Facilities
Summary
Fugitive
2.62E-03
2.95E-04
5.61E-05
1.63E-05
2.03E-07
2.86E-08
1.03E-08
3.41E-09
Handling asbestos-containing building materials during maintenance, renovation, and demolition activities
Grouping
Specific
Facilities
Summary
Fugitive
4.51E-03
6.37E-04
1.21E-04
3.05E-05
2.49E-07
2.34E-08
9.33E-09
3.48E-09
Waste handling, disposal, and treatment
Grouping
Specific
Fugitive
1.95E-03
2.55E-04
5.15E-05
1.43E-05
1.65E-07
2.23E-08
7.81E-09
2.65E-09
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Co-located General Population
General Population
Distance from source (m)
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Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Facilities
Summary
Handling articles or formulations that contain asbestos
Grouping
Specific
Facilities
Summary
Fugitive
3.09E-04
2.08E-04
1.96E-04
1.86E-04
4.43E-07
1.30E-07
5.01E-08
1.59E-08
9050 F.3.2 Central Tendency Ambient Air Concentration Summary Tables
9051
9052 TableApx F-9. Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery
Containing Asbestos OES Ceni
tral Tendency Ambient Air Concentrat
ions Summary Tab
e
Analysis
OES
Description
10 m
30 m
60 m
100 m
10,00 m
2,500 m
5,000 m
10,000 m
Specific
Facilities
Fugitive
6.22E-03
9.94E-04
2.23E-04
6.64E-05
2.35E-06
1.05E-07
3.78E-08
1.32E-08
Generic
Facilities
Rural
Fugitive
1.33E-05
2.60E-06
6.75E-07
2.10E-07
6.72E-09
2.52E-10
8.39E-11
3.11 E— 11
Generic
Facilities
Urban
Fugitive
1.30E-05
2.55E-06
6.45E-07
1.99E-07
6.20E-09
2.26E-10
7.86E-11
2.96E-11
Grouping
Average
Summary
Fugitive
2.08E-03
3.33E-04
7.47E-05
2.23E-05
7.89E-07
3.52E-08
1.27E-08
4.43E-09
9054
9055 Table Apx F-10. Handling Asbestos-Containing Building Materials During Maintenance,
9056 Renovation, and Demolition Activities OES Central Tendency Ambient Air Concentrations
9057 Summary Table
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Specific
Facilities
Fugitive
9.97E-03
1.89E-03
4.52E-04
1.33E-04
3.97E-06
1.53E-07
5.51E-08
2.09E-08
Generic
Facilities
Rural
Fugitive
5.65E-06
1.14E-06
3.05E-07
9.64E-08
3.04E-09
1.18E-10
3.75E-11
1.36E-11
Generic
Facilities
Urban
Fugitive
5.53E-06
1.13E-06
2.90E-07
9.03E-08
2.79E-09
1.03E-10
3.50E-11
1.3 IE—11
Grouping
Average
Summary
Fugitive
3.33E-03
6.31E-04
1.51E-04
4.44E-05
1.32E-06
5.10E-08
1.84E-08
6.98E-09
9058
9059
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TableApx F-ll. Handling Asbestos-Containing Building Materials During Firefighting or Other
Disaster Response Activities PES Central Tendency Ambient Air Concentrations Summary Table
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Generic
Facilities
Urban
Fugitive
4.22E-06
1.04E-06
3.01E-07
9.78E-08
3.21E-09
1.02E-10
3.19E-11
1.20E-11
Generic
Facilities
Rural
Fugitive
4.14E-06
1.07E-06
3.13E-07
1.02E-07
3.42E-09
1.05E-10
2.99E-11
1.09E-11
Grouping
Average
Summary
Fugitive
4.18E-06
1.06E-06
3.07E-07
1.00E-07
3.31E-09
1.04E-10
3.09E-11
1.15E-11
Table Apx F-12. Waste Handling, Disposal, and Treatment OES Central Tendency Ambient Air
Analysis
OES
Description
10 m
30 m
60 m
100 m
10,00 m
2,500 m
5,000 m
10,000 m
Grouping
Specific
Facilities
Summary
Fugitive
4.53E-03
7.74E-04
1.78E-04
5.28E-05
1.76E-06
7.44E-08
2.57E-08
9.08E-09
Table Apx F-13. Handling Articles or Formulations that Contain Asbestos OES Central
Tendency Ambient Air Concentrations Summary Table
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Grouping
Specific
Facilities
Summary
Fugitive
4.57E-04
2.37E-04
2.04E-04
1.94E-04
5.03E-06
2.77E-07
1.15E-07
4.04E-08
F.3.3 High-End Tendency Ambient Air Concentration Summary Tables
Table Apx F-14. Use, Repair, or Disposal of Industrial and Commercial Appliances or Machinery
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Generic
Facilities
Rural
Fugitive
1.5E-02
2.9E-03
7.6E-04
2.4E-04
7.6E-06
2.8E-07
9.4E-08
3.5E-08
Generic
Facilities
Urban
Fugitive
1.5E-02
2.9E-03
7.3E-04
2.2E-04
7.0E-06
2.5E-07
8.9E-08
3.3E-08
Specific
Facilities
Fugitive
1.1E-02
2.3E-03
5.9E-04
1.8E-04
8.7E-06
2.5E-07
8.7E-08
3.2E-08
Grouping
Average
Summary
Fugitive
1.4E-02
2.7E-03
6.9E-04
2.1E-04
7.7E-06
2.6E-07
9.0E-08
3.3E-08
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PUBLIC RELEASE DRAFT
April 2024
TableApx F-15. Handling Asbestos-Containing Building Materials during Maintenance,
Renovation, and Demolition Activities OES High-End Tendency Ambient Air Concentrations
Summary Table
Analysis
OES
Description
10 m
30 m
60 m
100 m
1000 m
2500 m
5000 m
10000 m
Specific
Facilities
Fugitive
1.7E-02
3.4E-
03
8.6E-04
2.6E-04
1.6E-05
3.1E-07
1.1E-07
3.9E-08
Generic
Facilities
Rural
Fugitive
1.1E-03
2.3E-
04
6.1E-05
1.9E-05
6.1E-07
2.4E-08
7.5E-09
2.7E-09
Generic
Facilities
Urban
Fugitive
1.1E-03
2.2E-
04
5.8E-05
1.8E-05
5.6E-07
2.1E-08
7.0E-09
2.6E-09
Grouping
Average
Summary
Fugitive
6.3E-03
1.3E-
03
3.3E-04
9.9E-05
5.8E-06
1.2E-07
4.0E-08
1.5E-08
Measured
Air
2.0E-02
Table Apx F-16. Handling Asbestos-Containing Building Materials During Firefighting or
Other Disaster Response Activities OES High-End Tendency Ambient Air Concentrations
Summary Table
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Generic
Facilities
Urban
Fugitive
8.4E-04
2.1E-04
6.0E-05
2.0E-05
6.4E-07
2.0E-08
6.4E-09
2.4E-09
Generic
Facilities
Rural
Fugitive
8.3E-04
2.1E-04
6.3E-05
2.0E-05
6.8E-07
2.1E-08
6.0E-09
2.2E-09
Grouping
Average
Summary
Fugitive
8.4E-04
2.1E-04
6.1E-05
2.0E-05
6.6E-07
2.1E-08
6.2E-09
2.3E-09
Measured
Air
2.2E-03
Table Apx F-17. Waste Handling, Disposal, and Treatment OES High-End Tendency Ambient
Air Concentrations Summary Table
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Grouping
Specific
Facilities
Summary
Fugitive
8.7E-03
1.8E-03
4.5E-04
1.4E-04
6.0E-06
1.6E-07
5.5E-08
2.0E-08
Measured
Air
6.3E-03
Page 344 of 405
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PUBLIC RELEASE DRAFT
April 2024
9085 TableApx F-18. Handling Articles or Formulations that Contain Asbestos OES High-End
Tendency Ambient Air Concent
trations Summary r
"able
Analysis
OES
Description
10 m
30 m
60 m
100 m
1,000 m
2,500 m
5,000 m
10,000 m
Grouping
Specific
Facilities
Summary
Fugitive
8.3E-04
3.2E-04
2.3E-04
2.1E-04
1.2E-05
4.5E-07
1.9E-07
6.9E-08
9087
Page 345 of 405
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PUBLIC RELEASE DRAFT
April 2024
Table Apx F-19. Ambien
Air Concentration Summary by
3ES
OES
COU
Distance from Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
Low-end tendency lifetime cancer ELCR
Waste handling, disposal, and
treatment fugitive
COU: Disposal, including distribution for
disposal
1.9E-03
2.5E-04
5.1E-05
1.4E-05
1.6E-07
2.2E-08
7.8E-09
2.7E-09
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
4.5E-03
6.4E-04
1.2E-04
3.0E-05
2.5E-07
2.3E-08
9.3E-09
3.5E-09
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive
COU: Construction, paint, electrical, and
metal products
2.6E-03
3.0E-04
5.6E-05
1.6E-05
2.0E-07
2.9E-08
1.0E-08
34E-09
Handling articles or
formulations that contain
asbestos fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
COU: Packaging, paper, plastic, toys,
hobby products
3.1E-04
2.1E-04
2.0E-04
1.9E-04
44E-07
1.3E-07
5.0E-08
1.6E-08
Central tendency lifetime cancer ELCR
Waste handling, disposal, and
treatment fugitive
COU: Disposal, including distribution for
disposal
4.5E-03
7.7E-04
1.8E-04
5.3E-05
1.8E-06
74E-08
2.6E-08
9.1E-09
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
3.3E-03
6.3E-04
1.5E-04
4.4E-05
1.3E-06
5.1E-08
1.8E-08
7.0E-09
Use, Repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive
COU: Construction, paint, electrical, and
metal products
2.1E-03
3.3E-04
7.5E-05
2.2E-05
7.9E-07
3.5E-08
1.3E-08
44E-09
Handling articles or
formulations that contain
asbestos fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
COU: Packaging, paper, plastic, toys,
hobby products
4.6E-04
2.4E-04
2.0E-04
1.9E-04
5.0E-06
2.8E-07
1.1E-07
4.0E-08
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
4.2E-06
1.1E-06
3.1E-07
1.0E-07
3.3E-09
1.0E-10
3.1E-11
1. IE—11
Page 346 of 405
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PUBLIC RELEASE DRAFT
April 2024
OES
cou
Distance from Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
High-end tendency lifetime cancer ELCR
Waste handling, disposal, and
treatment fugitive
COU: Disposal, including distribution for
disposal
8.7E-03
1.8E-03
4.5E-04
1.4E-04
6.0E-06
1.6E-07
5.5E-08
2.0E-08
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, Cleaning, Treatment
Care Products
6.3E-03
1.3E-03
3.3E-04
9.9E-05
5.8E-06
1.2E-07
4.0E-08
1.5E-08
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive
COU: Construction, paint, electrical, and
metal products
1.4E-02
2.7E-03
6.9E-04
2.1E-04
7.7E-06
2.6E-07
9.0E-08
3.3E-08
Handling articles or
formulations that contain
asbestos fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
COU: Packaging, paper, plastic, toys,
hobby products
8.3E-04
3.2E-04
2.3E-04
2.1E-04
1.2E-05
4.5E-07
1.9E-07
6.9E-08
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive
COU: Construction, paint, electrical, and
metal products
COU: Furnishing, cleaning, treatment care
products
8.4E-04
2.1E-04
6.1E-05
2.0E-05
6.6E-07
2.1E-08
6.2E-09
2.3E-09
9089
Page 347 of 405
-------
9090
9091
9092
9093
9094
9095
9096
9097
9098
9099
9100
9101
9102
9103
9104
9105
9106
9107
9108
9109
9110
9111
9112
9113
9114
9115
PUBLIC RELEASE DRAFT
April 2024
F.4 Water Pathway
F.4.1 Surface Water
Measured concentrations of Asbestos in Surface Water with unit of f/cc, extracted from 19 sources, are
presented in FigureApx F-l 1 and supplemental information is summarized in Table Apx F-20. More
than one asbestos analysis method was reported and overall concentrations provided in the bullets that
follow:
• Concentrations for EDS ranged from not detected to 0.215373 f/cc from three samples collected
in 2016 in one country (Italy). Location types were categorized as General Population and Near
Facility. Reported detection frequency was 1.0.
• Concentrations for N/R ranged from 6,200.0 to 58,000.0 f/cc from 30 samples collected
between 2009 and 2011 in 1 country (United States). Location types were categorized as
General Population. Reported detection frequency was 0.3.
• Concentrations for PIXE, TEM ranged from 230.0 to 3,200.0 f/cc from two samples collected in
1981 in 1 country (Canada). Location types were categorized as Near Facility. Reported
detection frequency was 1.0.
• Concentrations for PLM ranged from 100.0 to 1,200,000.0 f/cc from 502 samples collected in
2014 in 1 country (United States). Location types were categorized as Near Facility. Reported
detection frequency was 0.77.
• Concentrations for SEM were 9,500.0 f/cc from one sample collected in 1971 in one country
(Canada). Location types were categorized as General Population. Reported detection frequency
was 1.0.
• Concentrations for TEM ranged from not detected to 30,000,000,000.0 f/cc from 2,355 samples
collected between 1972 and 2009 in 4 countries (Canada, Great Britain, Greece, and United
States). Location types were categorized as General Population and Near Facility. Reported
detection frequency ranged from 0.6 to 1.0.
Page 348 of 405
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PUBLIC RELEASE DRAFT
April 2024
NonUS - EDS
3361883 - Turci, et al.. 2016 - IT
3361883 - Turci, et al., 2016 - IT
US-NR
(¦¦¦$ General Population
¦¦HI Near Facility
1
3970353 - ATSDR, 2015 - US*
NonUS - PIXE. TEM
3647785 - Desaulniers, et al., 1981 - CA
US - PLM
—
3970087 - CDM Federal Programs Corporation, 2014 - US*
NonUS - SEM
3615476 - Cunningham and Pontefract, 1971 - CA
US -TEM
2815086 - Puffer, et al., 1987 - US
6900895 - Puffer, et al., 1983 - US
3581435 - Maresca, et al., 1984 - US
¦
3580912-Pitt, 1988-US
3581573 - McMillan, et al., 1977 - US
mm
6893858 - Stewart, et al., 1977 - US
6893858 - Stewart, et al., 1977 - US
6886427 - Cooper and Murchio, 1974 - US
NonUS - TEM
2604491 - Emmanouil, et al., 2009 - GR
3581609 - Bacon, et al., 1986 - CA
3581609 - Bacon, et al., 1986 - CA
6868189 - Monaro, et al., 1981 - CA
6883124 - Conway and Lacey, 1984 - GB
6896746 - Schreier and Taylor, 1981 - CA
6896746 - Schreier and Taylor, 1981 - CA
6889167 - Durham and Pang, 1976 - CA
3581077 - Kay, 1974-CA
0.01
100 10M 10A6 10A8 10AI0
Concentration (f/cc)
9117 Figure Apx F-ll. Concentrations of Asbestos (f/cc) in Surface Water from 1971 to 2016
9118 * = Reference used in risk determination
9119
Page 349 of 405
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9120
9121
PUBLIC RELEASE DRAFT
April 2024
TableApx F-20. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
Surface Water
Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
EDS
(Turci et al..
Chrysotile
0.8(iin
IT
General
2016
1 (1.00)
N/R
Medium
2016)
(asbestifonn of
mineral
serpentine)
Population
(Turci et al..
Chrysotile
0.8(iin
IT
Near
2016
2(1.00)
N/R
Medium
2016)
(asbestifonn of
mineral
serpentine)
Facility
N/R
(AT SDR.
General
N/R
US
General
2009-2011
30 (0.30)
N/R
Medium
2015)
Population
PIXE, TEM
(Desaulniers
General
N/R
CA
Near
1981
2(1.00)
N/R
Medium
et al.. 1981)
Facility
PLM
(CDM
General
N/R
US
Near
2014
502 (0.77)
N/R
Medium
Federal
Tremolite
Facility
Programs
Corporation.
2014)
SEM
(Cunningham
General
N/R
CA
General
1971
1 (1.00)
N/R
Medium
and
Pontefract.
Population
1971)
TEM
(Puffer et al..
General
0.1 nm
US
General
1987
8 (0.88)
N/R
Medium
1987)
Population
(Puffer et al..
1983)
Chrysotile
(asbestifonn of
mineral
serpentine)
Crocidolite
(asbestifonn of
mineral
riebeckite)
0.55
l_im
1.0 nm
US
General
Population
1981-1982
8 (1.00)
N/R
Medium
(Maresca et
Chrysotile
0.55
US
Near
1981
7 (N/R)
N/R
Medium
al.. 1984)
(asbestifonn of
mineral
serpentine)
0.71
Facility
(Pitt. 1988)
Chrysotile
(asbestifonn of
mineral
serpentine)
Crocidolite
(asbestifonn of
~1 (iin
US
General
Population
1979-1980
5 (1.00)
N/R
Medium
Page 350 of 405
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PUBLIC RELEASE DRAFT
April 2024
Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency of
Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
mineral
riebeckite)
Anthophyllite
Tremolite
Actinolite
General
(McMillan et
al.. 1977)
General
N/R
US
General
Population
1974-1975
2028 (1.00)
N/R
Medium
(Stewart et
al.. 1977)
Chrysotile
(asbestifonn of
mineral
serpentine)
General
>5
US
Near
Facility
1975
43 (0.65)
N/R
Medium
(Stewart et
al.. 1977)
General
>5
us
Near
Facility
1975
36 (0.64)
N/R
Medium
(Cooper and
Murchio.
1974)
Chrysotile
(asbestifonn of
mineral
serpentine)
2-10
l_im
long
us
General
Population
1973
5 (0.60)
N/R
Medium
(Emmanouil
et al.. 2009)
Chrysotile
(asbestifonn of
mineral
serpentine)
Anthophyllite
Tremolite
Actinolite
N/R
GR
Near
Facility
2009
5 (N/R)
N/R
Medium
(Bacon et al..
1986)
General
N/R
CA
General
Population
1981
6(1.00)
N/R
Medium
(Bacon et al..
1986)
General
N/R
CA
Near
Facility
1981
24(1.00)
N/R
Medium
(Monaro et
al.. 1981)
General
N/R
CA
Near
Facility
1981
10 (N/R)
N/R
Low
(Conwav and
Lacev. 1984)
Chrysotile
(asbestifonn of
mineral
serpentine)
General
£2
11
i
GB
General
Population
1980
2(1.00)
410,830.0
Medium
(Schreier and
Tavlor. 1981)
General
N/R
CA
General
Population
1979-1980
18 (1.00)
N/R
Medium
(Schreier and
Tavlor. 1981)
General
N/R
CA
Near
Facility
1979-1980
8 (1.00)
N/R
Medium
(Durham and
Pane. 1976)
General
<1 (mi
CA
General
Population
1973-1974
130 (0.94)
100.0
Medium
(Kav. 1974)
General
3 urn
CA
General
Population
1972
12(1.00)
N/R
Medium
CA = Canada; GB = Great Britain; IT = Italy; PL = Poland; US = United States
Page 351 of 405
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9122
9123
9124
9125
9126
9127
9128
9129
9130
9131
9132
9133
9134
9135
9136
9137
9138
9139
9140
9141
9142
9143
PUBLIC RELEASE DRAFT
April 2024
F.4.2 Drinking Water
Overall measured concentrations of asbestos in drinking water with unit of f/cc, extracted from 17
sources, are summarized in FigureApx F-12 and supplemental information is provided in Table Apx
F-21. More than one asbestos analysis method was reported and each summarized separately the bullets
that follow:
• Concentrations for PCME were 600.0 f/cc from three samples collected in 2007 in one country
(Poland). Location types were categorized as General Population. Reported detection frequency
was not reported.
• Concentrations for SEM ranged from not detected to 172,700.0 f/cc from 100 samples collected
between 1971 and 1978 in 2 countries (Canada and United States). Location types were
categorized as General Population. Reported detection frequency was 1.0.
• Concentrations for SEM, EDX ranged from 0.004 to 0.688 f/cc from 15 samples collected in
2005 in 2 countries (Japan and South Korea). Location types were categorized as Near Facility.
Reported detection frequency was 1.0.
• Concentrations for TEM ranged from not detected to 260,000,000.0 f/cc from 502 samples
collected between 1972 and 2011 in 3 countries (Canada, Great Britain, and United States).
Location types were categorized as General Population, Consumer Use and Near Facility.
Reported detection frequency ranged from 0.2 to 1.0.
• Concentrations for Thom cell and optical microscope ranged from 70.0 to 5,200.0 f/cc from 39
samples collected in 2007 in 1 country (Poland). Location types were categorized as General
Population. Reported detection frequency was not reported.
Page 352 of 405
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PUBLIC RELEASE DRAFT
April 2024
9144
9145
9146
9147
NonUS - PCME
US - SEM
3580600 - Zielina, el al., 2007 - PL
3615476 - Kanarek, et a!., 1981 ¦ US
NonUS - SEM
3615476 - Cunningham and Pontefract, 1971 - CA
4168732 - Cunningham and Pontefract, 1971 - CA
NonUS - SEM. EDX
3970349 - Ma and Kang, 2017 - KRiJP
US - TEM
NonUS - TEM
3583096 - Atsdr, 2012 - US*
3583096 - Webber, et al., 1988 - US
3585730 - Webber, et al., 1988 - US
3585730 - Hay ward, 1984 - US
6900895 - Hay ward, 1984 - US
3583025 - Puffer, et al., 1983 - US
6896139 - Buelow, et al., 1980 - US
6896139-Anl, 1979-US
6912600-Anl, 1979 - US
6912600-U.S, 1976-US
3581573 -U.S, 1976-US
6893858 - McMillan, et al., 1977 - US
6886427 - Stewart, et al., 1977 - US
3581609 - Cooper and Murchio, 1974 - US
6883124 - Bacon, et al., 1986 - CA
6883124 - Conway and Lacey, 1984 - GB
3581077 - Conway and Lacey, 1984 - GB
3581127 - Kay, 1974-CA
NonUS - Thorn cell and high quality optical microscope
3581127 - Zielina, et al., 2007 - PL
10*-5
General Population
| Near Facility
I Consumer Use
Non-Detect
0.001
0.1
10 1000
Concentration (f/cc)
10A5
10A7
10A9
FigureApx F-12. Concentrations of Asbestos (f/cc) in Drinking Water from 1971 to 2011
* = Reference used in risk evaluation
Page 353 of 405
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PUBLIC RELEASE DRAFT
April 2024
9148 TableApx F-21. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
9149 Drinking Water
Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency
of Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
PCME
(Zielina et al..
General
<10 |nn
PL
General
2007
3 (N/R)
N/R
Medium
2007)
Population
SEM
(Kanarek et
al.. 1981)
Chrysotile
(asbestifonn
of mineral
serpentine)
0.45 urn
US
General
Population
1974-1978
78 (N/R)
10,100.0
Medium
(Cunningham
General
N/R
CA
General
1971
14(1.00)
N/R
Medium
and
Pontefract.
Population
1971)
(Cunningham
General
N/R
CA
General
1971
8 (1.00)
N/R
Medium
and
Pontefract.
Population
1971)
SEM, EDX
(Ma and
Kang. 2017)
Chrysotile
(asbestifonn
of mineral
serpentine)
Crocidolite
(asbestifonn
of mineral
riebeckite)
Amosite
(asbestifonn
of mineral
grunerite)
N/R
JP, KR
Near
Facility
2005
15 (1.00)
N/R
Medium
TEM
(AT SDR.
2012)
Chrysotile
(asbestifonn
of mineral
serpentine)
>5 (4m
US
Near
Facility
2011
5 (0.20)
6,090.0
Medium
(Webber et
Chrysotile
N/R
US
General
1985-1986
3 (1.00)
N/R
Medium
al.. 1988)
(asbestifonn
of mineral
serpentine)
Population
(Webber et
al.. 1988)
Chrysotile
(asbestifonn
of mineral
serpentine)
N/R
us
Near
Facility
1985-1986
2(1.00)
N/R
Medium
(Havward.
1984)
Chrysotile
(asbestifonn
of mineral
serpentine)
N/R
us
Near
Facility
1982
2(1.00)
N/R
Medium
Page 354 of 405
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PUBLIC RELEASE DRAFT
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Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency
of Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
(Havward.
1984)
Chrysotile
(asbestifonn
of mineral
serpentine)
N/R
US
Near
Facility
1982
10(1.00)
N/R
Medium
(Puffer et al..
1983)
Crocidolite
(asbestifonn
of mineral
riebeckite)
Tremolite
1.0 nm
2.8 |_im
US
General
Population
1982
8 (1.00)
N/R
Medium
(Buelow et
al.. 1980)
General
Chrysotile
(asbestifonn
of mineral
serpentine)
0.7 to 60
|im
0.3 to 40
|im
us
General
Population
1975-1979
94 (0.41)
N/R
Medium
(ANL. 1979)
Chrysotile
(asbestifonn
of mineral
serpentine)
5 urn
us
Near
Facility
1976
1 (1.00)
120.0
Medium
(ANL. 1979)
General
5 urn
us
Near
Facility
1976
2(1.00)
47.0
Medium
(U.S. EPA.
1976)
General
Chrysotile
(asbestifonn
of mineral
serpentine)
N/R
us
General
Population
1975-1976
104 (0.39)
3,300.0
Medium
(U.S. EPA.
1976)
Crocidolite
(asbestifonn
of mineral
riebeckite)
Amosite
(asbestifonn
of mineral
grunerite)
Chrysotile
(asbestifonn
of mineral
serpentine)
N/R
us
General
Population
1975-1976
10(1.00)
5,000.0
Medium
(McMillan et
al.. 1977)
General
N/R
us
General
Population
1974-1975
234 (1.00)
N/R
Medium
(Stewart et al..
1977)
Chrysotile
(asbestifonn
of mineral
serpentine)
>5
us
Near
Facility
1975
1 (1.00)
N/R
Medium
(Cooper and
Murchio.
1974)
Chrysotile
(asbestifonn
of mineral
serpentine)
2-10 |nn
long
us
General
Population
1973-1974
2(1.00)
N/R
Medium
(Bacon et al..
1986)
General
N/R
CA
Near
Facility
1981
2(1.00)
N/R
Medium
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9153
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9155
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9158
9159
9160
9161
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Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency
of Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
(Conwav and
Lacev. 1984)
Chrysotile
(asbestifonn
of mineral
serpentine)
General
35 |_im to
<2 nm
GB
Consumer
Use
1980
8 (1.00)
8,601,460.
0
Medium
(Conwav and
Lacev. 1984)
Chrysotile
(asbestifonn
of mineral
serpentine)
General
35 |_im to
<2 nm
GB
General
Population
1980
8 (0.75)
38104320.
0
Medium
(Kav. 1974)
General
3 urn
CA
General
Population
1972
6(1.00)
N/R
Medium
Thorn cell and optical microscope
(Zielina et al..
2007)
General
>10 nm
<10 nm
PL
General
Population
2007
39 (N/R)
N/R
Medium
CA = Canada; GB = Great Britain; PL = Poland; US = United States
F.4.3 Groundwater
Overall measured concentrations of asbestos in groundwater with unit of f/cc, extracted from 6 sources,
are summarized in FigureApx F-13 and supplemental information is provided in Table Apx F-22.
More than one analysis method was reported and summarized in the bullets that follow:
• Overall, concentrations for EDS ranged from not detected to 1.076863 f/cc from two samples
collected in 2016 in one country (Italy). Location types were categorized as General Population
and Near Facility. Reported detection frequency was 1.0.
• Overall, concentrations for TEM ranged from not detected to 34,204,000.0 f/cc from 52 samples
collected between 1980 and 2011 in 3 countries (Canada, Great Britain, and United States).
Location types were categorized as General Population and Near Facility. Reported detection
frequency ranged from 0.7 to 1.0.
NonUS- EDS
3361883 - Turci, et al., 2016 - IT
3361883 -Turci, et al., 2016 - IT
US -TEM
General Population
Near Facility
3970349 - Atsdr, 2012 - US*
3585730 - Hayward, 1984 - US
6900895 - Puffer, et al., 1983 - US
NonUS - TEM
3581609 - Bacon, et al., 1986 - CA
3581609 - Bacon, et al., 1986 - CA
1
6883124 - Conway and Lacey, 1984 - GB
10A-4 0.01
100 10*4 10A6 10A8
Concentration (f/cc)
Figure Apx F-13. Concentrations of Asbestos (f/cc) in Groundwater from 1980 to 2016
* = Reference used in risk determination
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9166 TableApx F-22. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
9167 Groundwater
Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency
of Detection)
Detection
Limit (f/cc)
Overall
Quality
Level
EDS
(Turci et
al.. 2016)
Chrysotile
(asbestifor
m of
mineral
serpentine)
0.8|4in
IT
General
Population
2016
1 (1.00)
N/R
Medium
(Turci et
al.. 2016)
Chrysotile
(asbestifor
m of
mineral
serpentine)
0.8|4in
IT
Near
Facility
2016
1 (1.00)
N/R
Medium
TEM
(AT SDR.
2012)
Chrysotile
(asbestifor
m of
mineral
serpentine)
> 5 (4m
US
Near
Facility
2009-2011
23 (0.70)
200.0
Medium
(Havward.
1984)
Chrysotile
(asbestifor
m of
mineral
serpentine)
N/R
US
Near
Facility
1982
7(1.00)
N/R
Medium
(Puffer et
al.. 1983)
General
Crocidolite
(asbestifor
m of
mineral
riebeckite)
N/R
1.0 (4111
US
General
Population
1981-1982
8 (1.00)
N/R
Medium
(Bacon et
al.. 1986)
General
N/R
CA
General
Population
1981
2(1.00)
N/R
Medium
(Bacon et
al.. 1986)
General
N/R
CA
Near
Facility
1981
4(1.00)
N/R
Medium
(Conwav
and Lacev.
1984)
Chrysotile
(asbestifor
m of
mineral
serpentine)
General
35 (im
to < 2
(4111
GB
Near
Facility
1980
8 (1.00)
43,208,550.0
Medium
CA= Canada; GB = Great Britain; IT = Italy; US = Unites States
9168 F.4.4 Sediment
9169 Measured concentrations of Asbestos in Sediment with unit of f/cm3, extracted from one source, are
9170 summarized in FigureApx F-14 and supplemental information is provided in Table Apx F-23.
9171 Overall, concentrations ranged from not detected to 0.13 f/cm3 from 16 samples collected between
9172 1995 and 1998 in 1 country (United States). Location types were categorized as General Population and
9173 Near Facility. Reported detection frequency ranged from 0.88 to 1.0.
9174
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9177
9178
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9186
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| General Population
US - TEM
Near Facility
3085166 - Webber, et al., 2004 - US
3085166 - Webber, et al., 2004 - US
10A-4
0.001
0.01
0.1 1
Concentration (f/cc)
FigureApx F-14. Concentrations of Asbestos (f/cm3) in the TEM Method of Sediment from 1995
to 1998
TableApx F-23. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cm3) Levels
in the TEM Method of Sediment
Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year
Sample Size
(Frequency of
Detection)
Detection
Limit
(f/cm3)
Overall
Quality
Level
(Webber et
al.. 2004)
Chrysotile
(asbestiform
of mineral
serpentine)
Anthophyllite
N/R
US
General
Population
1995-1998
8 (0.88)
N/R
Medium
(Webber et
al.. 2004)
Chrysotile
(asbestiform
of mineral
serpentine)
Anthophyllite
N/R
US
Near Facility
1995-1998
8 (1.00)
N/R
Medium
US = United States
F.4.5 Wastewater
Measured concentrations of asbestos in wastewater with unit of f/cc, extracted from one source, are
summarized in Figure Apx F-15 and supplemental information is provided in Table Apx F-24.
Overall, concentrations ranged from 0.064 to 10,000,000 f/cc from seven samples collected in 1975 in
one country (United States). Location types were categorized as Untreated Effluent at Discharge
Origin. Reported detection frequency was 0.57.
US -TEM
Untreated Effluent at Discharge Origin
6893858 - Stewart, et al., 1977 - US
0.001
0.1
10 1000 10A5
10A7
Concentration (f/cc)
Figure Apx F-15. Concentrations of Asbestos (f/cc) in the TEM Method of Wastewater in
Untreated Effluent at Discharge Origin Locations in 1975
Table Apx F-24. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
the TEM Method of Wastewater
Citation
Fiber Type
Fiber
Size
Country
Location
Type
Sampling
Year
Sample Size
(Frequency of
Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
(Stewart et
al.. 1977)
Chrysotile
(asbestiform
of mineral
serpentine)
General
>5
US
Untreated
Effluent at
Discharge
Origin
1975
7(0.57)
N/R
Medium
US = United States
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9194
9195
9196
9197
9198
9199
9200
9201
9202
9203
9204
9205
9206
9207
9208
9209
9210
9211
9212
9213
9214
9215
9216
9217
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F.5 Soil
Measured concentrations of asbestos in soil with unit of f/cc, extracted from one source, are
summarized in FigureApx F-16 and supplemental information is provided in TableApx F-25.
Overall, concentrations ranged from 0.013 to 0.86 f/cc from four samples collected in 2010 in one
country (United States). Location types were categorized as Near Facility. Reported detection
frequency was not reported.
US Drv - TEM
2620594 - Jones, et al., 2010 - US*
HI Near Facility
0.001
0.01
0.1 1
Concentration (f/cc)
Figure Apx F-16. Concentrations of Asbestos (f/cc) in the TEM Method of Soil in Near Facility
Locations in 2010
* = Reference used in risk determination
Table Apx F-25. Summary of Peer-Reviewed Literature that Measured Asbestos (f/cc) Levels in
the TEM Method of Soil
Citation
Fiber
Type
Fiber
Size
Country
Location
Type
Sampling
Year
Sample Size
(Frequency of
Detection)
Detection
Limit
(f/cc)
Overall
Quality
Level
(Jones et
al.. 2010)
General
N/R
US
Near
Facility
2010
4 (N/R)
N/R
Medium
US = United States
Measured concentrations of asbestos in soil with unit of s/cc, extracted from one source, are
summarized in Figure Apx F-17 and supplemental information is provided in Table Apx F-26.
Overall, concentrations were not detected s/cc from 1,000 samples collected between 2001 and 2012 in
1 country (United States). Location types were categorized as General Population. Reported detection
frequency was not reported.
US - PCM
3970083 - CDM Federal Programs Corporation, 2015 - US*
¦ General Population
E5 Non-Detect
•
IOA-6
10*-5
10A-4
0.001 0.01 0.1
Concentration (s/cc)
10
Figure Apx F-17. Concentrations of Asbestos (s/cc) in the PCM Method of Soil in General
Population Locations from 2001 to 2012
* = Reference used in risk determination
Table Apx F-26. Summary of Peer-Reviewed Literature that Measured Asbestos (s/cc) Levels in
the PCM Method of Soil
Citation
Fiber
Type
Fiber
Size
Country
Location
Type
Sampling
Year(s)
Sample Size
(Frequency
of Detection)
Detection
Limit
(s/cc)
Overall
Quality
Level
(CDM Federal
Programs
Corporation.
2015)
General
N/R
US
General
Population
2001-2012
1,000 (N/R)
0.005
High
US = United States
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9223
9224
9225
9226
9227
9228
9229
9230
9231
9232
9233
9234
9235
9236
9237
9238
9239
9240
9241
9242
9243
9244
9245
9246
9247
9248
9249
9250
9251
9252
9253
9254
9255
9256
9257
9258
9259
9260
9261
9262
9263
9264
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Appendix G ENVIRONMENTAL HAZARD DETAILS
G.J Approach and Methodology
For aquatic species, EPA estimates hazard by calculating a concentration of concern (COCs) for a
hazard threshold. COCs can be calculated using a deterministic method by dividing a hazard value by
an assessment factor (AF) according to EPA methods (Suter. 2016; U.S. EPA. 2013. 2012) and
EquationApx G-1.
EquationApx G-l.
COC = toxicity value/AF
COCs can be calculated using deterministic or probabilistic methods. For asbestos, EPA used a
deterministic method to calculate the acute and both chronic COCs. Two chronic COCs were calculated
due to the physiological differences between fish and mollusks.
G.2 Hazard Identification
G.2.1 Weight of Scientific Evidence
EPA used the strength-of-evidence and uncertainties from (U.S. EPA. 2021) for the hazard assessment
to qualitatively rank the overall confidence using evidence Table 4-3 for environmental hazard.
Confidence levels of robust (+ + +), moderate (+ +), slight (+), or indeterminant are assigned for each
evidence property that corresponds to the evidence considerations (U.S. EPA. 2021). The rank of the
Quality of the Database consideration is based on the systematic review data quality rank (high,
medium, or low) for studies used to calculate the hazard threshold, and whether there are data gaps in
the toxicity data set. Another consideration in the Quality of the Database is the risk of bias (i.e., how
representative is the study to ecologically relevant endpoints). Additionally, because of the importance
of the studies used for deriving hazard thresholds, the Quality of the Database consideration may have
greater weight than the other individual considerations. The high, medium, and low systematic review
ranks correspond to the evidence table ranks of robust (+ + +), moderate (+ +), or slight (+),
respectively. The evidence considerations are weighted based on professional judgment to obtain the
Overall Confidence for each hazard threshold. In other words, the weights of each evidence property
relative to the other properties are dependent on the specifics of the weight of scientific evidence and
uncertainties that are described in the narrative and may or may not be equal. Therefore, the overall
score is not necessarily a mean or defaulted to the lowest score. The confidence levels and uncertainty
type examples are described below.
Confidence Levels
• Robust (+ + +) confidence suggests thorough understanding of the scientific evidence and
uncertainties. The supporting weight of scientific evidence outweighs the uncertainties to the
point where it is unlikely that the uncertainties could have a significant effect on the exposure or
hazard estimate.
• Moderate (+ +) confidence suggests some understanding of the scientific evidence and
uncertainties. The supporting scientific evidence weighed against the uncertainties is reasonably
adequate to characterize exposure or hazard estimates.
• Slight (+) confidence is assigned when the weight of scientific evidence may not be adequate to
characterize the scenario, and when the assessor is making the best scientific assessment
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9269
9270
9271
9272
9273
9274
9275
9276
9277
9278
9279
9280
9281
9282
9283
9284
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9286
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April 2024
possible in the absence of complete information. There are additional uncertainties that may
need to be considered.
• Indeterminant (NA) corresponds to entries in evidence tables where information is not available
within a specific evidence consideration.
Types of Uncertainties
The uncertainties may be relevant to one or more of the weight of scientific evidence considerations
listed in Table 4-3 are integrated into that property's rank in the evidence table.
• Scenario uncertainty: Uncertainty regarding missing or incomplete information needed to fully
define the exposure and dose.
o The sources of scenario uncertainty include descriptive errors, aggregation errors, errors
in professional judgment, and incomplete analysis.
• Parameter uncertainty: Uncertainty regarding some parameter.
o Sources of parameter uncertainty include measurement errors, sampling errors,
variability, and use of generic or surrogate data.
• Model uncertainty: Uncertainty regarding gaps in scientific theory required to make predictions
on the basis of causal inferences.
o Modeling assumptions may be simplified representations of reality.
Table Apx G-l summarizes the weight of scientific evidence and uncertainties, while increasing
transparency on how EPA arrived at the overall confidence level for each exposure hazard threshold.
Symbols are used to provide a visual overview of the confidence in the body of evidence, although de-
emphasizing an individual ranking that may give the impression that ranks are cumulative (e.g., ranks
of different categories may have different weights).
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9289 TableApx G-l. Considerations that Inform Evaluations of the Strength of the Evidence within an Evidence Stream {i.e., Apical
9290 Endpoints, Mechanistic, or Field Studies)
Consideration
Increased Evidence Strength (of the Apical
Endpoints, Mechanistic, or Field Studies Evidence)
Decreased Evidence Strength (of the Apical Endpoints, Mechanistic, or
Field Studies Evidence)
The evidence considerations and criteria laid out here guide the application of strength-of-evidence judgments for an outcome or environmental hazard effect
within a given evidence stream. Evidence integration or synthesis results that do not warrant an increase or decrease in evidence strength for a given
consideration are considered "neutral" and are not described in this table (and, in general, are captured in the assessment-specific evidence profile tables).
Quality of the database'1
(risk of bias)
• A large evidence base of high- or /wec/nww-quality
studies increases strength.
• Strength increases if relevant species are represented
in a database.
• An evidence base of mostly /ow-quality studies decreases strength.
• Strength also decreases if the database has data gaps for relevant species,
i.e., a trophic level that is not represented.
• Decisions to increase strength for other considerations in this table
should generally not be made if there are serious concerns for risk of
bias; in other words, all the other considerations in this table are
dependent upon the quality of the database.'1
Consistency
Similarity of findings for a given outcome (e.g., of a
similar magnitude, direction) across independent
studies or experiments increases strength, particularly
when consistency is observed across species, life stage,
sex, wildlife populations, and across or within aquatic
and terrestrial exposure pathways.
• Unexplained inconsistency (i.e., conflicting evidence; see U.S. EPA
(2005)) decreases strength.
• Strength should not be decreased if discrepant findings can be reasonably
explained by study confidence conclusions; variation in population or
species, sex, or life stage; frequency of exposure (e.g., intermittent or
continuous); exposure levels (low or high); or exposure duration.
Strength (effect
magnitude) and precision
• Evidence of a large magnitude effect (considered
either within or across studies) can increase strength.
• Effects of a concerning rarity or severity can also
increase strength, even if they are of a small
magnitude.
• Precise results from individual studies or across the
set of studies increases strength, noting that
biological significance is prioritized over statistical
significance.
• Use of probabilistic model (e.g., Web-ICE, SSD)
may increase strength.
Strength may be decreased if effect sizes that are small in magnitude are
concluded not to be biologically significant, or if there are only a few
studies with imprecise results.
Biological gradient/dose-
response
• Evidence of dose-response increases strength.
• Dose-response may be demonstrated across studies
or within studies and it can be dose- or duration-
dependent.
• Dose-response may not be a monotonic dose-
response (monotonicity should not necessarily be
• A lack of dose-response when expected based on biological
understanding and having a wide range of doses/exposures evaluated in
the evidence base can decrease strength.
• In experimental studies, strength may be decreased when effects resolve
under certain experimental conditions (e.g., rapid reversibility after
removal of exposure).
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Consideration
Increased Evidence Strength (of the Apical
Endpoints, Mechanistic, or Field Studies Evidence)
Decreased Evidence Strength (of the Apical Endpoints, Mechanistic, or
Field Studies Evidence)
expected, e.g., different outcomes may be expected
at low vs. high doses due to activation of different
mechanistic pathways or induction of systemic
toxicity at very high doses).
• Decreases in a response after cessation of exposure
(e.g., return to baseline fecundity) also may increase
strength by increasing certainty in a relationship
between exposure and outcome (this particularly
applicable to field studies).
• However, many reversible effects are of high concern. Deciding between
these situations is informed by factors such as the toxicokinetics of the
chemical and the conditions of exposure Iscc U.S. EPA (1998)1. endooint
severity, judgments regarding the potential for delayed or secondary
effects, as well as the exposure context focus of the assessment (e.g.,
addressing intermittent or short-term exposures).
• In rare cases, and typically only in toxicology studies, the magnitude of
effects at a given exposure level might decrease with longer exposures
(e.g., due to tolerance or acclimation).
• Like the discussion of reversibility above, a decision about whether this
decreases evidence strength depends on the exposure context focus of the
assessment and other factors.
• If the data are not adequate to evaluate a dose-response pattern, then
strength is neither increased nor decreased.
Biological relevance
Effects observed in different populations or
representative species suggesting that the effect is
likely relevant to the population or representative
species of interest (e.g., correspondence among the
taxa, life stages, and processes measured or observed
and the assessment endpoint).
An effect observed only in a specific population or species without a clear
analogy to the population or representative species of interest decreases
strength.
Physical/chemical
relevance
Correspondence between the substance tested and the
substance constituting the stressor of concern.
The substance tested is an analogue of the chemical of interest or a mixture
of chemicals which include other chemicals besides the chemical of
interest.
Environmental relevance
Correspondence between test conditions and conditions
in the region of concern.
The test is conducted using conditions that would not occur in the
environment.
" Database refers to the entire data set of studies integrated in the environmental hazard assessment and used to inform the strength of the evidence. In this context,
database does not refer to a computer database that stores aggregations of data records such as the ECOTOX Knowledgebase.
9291
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9293
9294
9295
9296
9297
9298
9299
9300
9301
9302
9303
9304
9305
9306
9307
9308
9309
9310
9311
9312
9313
9314
9315
9316
9317
9318
9319
9320
9321
9322
9323
9324
9325
9326
9327
9328
9329
9330
9331
9332
9333
9334
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9336
9337
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Appendix H CONSUMER EXPOSURE DETAILS
H.l Concentrations of Asbestos in Activity-Based Scenarios
Studies identified in Table 3-5 were used to estimate exposure concentrations for each activity-based
scenario. The following subsections are organized by COU and subcategory; each subsection discusses
the activity-based scenario's study methods and identifies the applicable data chosen for use in this
exposure assessment. The concentrations identified for bystanders were generally either reported area air
concentrations or approximated concentrations using a reduction factor (RF). For activity-based
scenarios that have reported both personal data (which represents DIY users) and area data (which
represents bystanders), RFs were calculated by dividing the personal exposure concentration by the area
exposure concentration. The resulting RFs were averaged across all activity-based scenarios to obtain an
overall average default RF value of 6. This RF was used to approximate concentrations for activity-
based scenarios that did not have bystander (area) data reported. For these scenarios, the reported
personal exposure concentration for DIY users was divided by 6 to obtain the bystander exposure
concentration. The scenarios evaluated quantitatively extracted data are summarized in Table 3-6.
H.l.l Construction, Paint, Electrical, and Metal Products COU
The activity-based scenarios evaluated under this COU relate to construction and building material
products; the activities consist of disturbing, maintaining or repairing the products or removing the
products. Disturbance, maintenance, or repair activities may involve product modification such as
sanding, cutting, or drilling of products and cleaning after the activities. Removing the products may
also involve product modification such as breaking and cutting.
New installation activities were not considered due to the low likelihood of consumers acquiring new or
unused commercial asbestos-containing products to use or install. In the United States, due to health
concerns, asbestos-containing construction products are no longer produced and have been replaced by
substitute materials that do not contain asbestos (U.S. EPA. 1989). Furthermore, the product
modification actions consumers might undertake during installations are likely similar to those during
maintenance or repair (e.g., cutting and sanding). It is assumed that product installation may take a
longer amount of time but might be done on a less frequent basis, while repair work may take a shorter
amount of time but might be done more often. Overall, potential exposures are expected to be
comparable, therefore the exposures evaluated for maintenance and repair activities can also represent
installation activities.
The activity-based scenarios and studies are summarized below, and the selected concentration data for
quantitative evaluation are shown in Table 3-6. For each scenario, low-end, central tendency, and high-
end concentrations were determined where possible, as described below.
Subcategory: Construction and Building Materials Covering Large Surface Areas
Outdoor, Disturbance Repair (Sanding or Scraping) of Roofing Materials: Mowat et al. (2007)
evaluated five chrysotile asbestos-containing commercial roofing products that were sold in the 1950s,
1960s and 1970s. The products included two "plastic roof cements" that contained 4.3 to 15.5 percent
chrysotile and three "fibered roof coatings" that contained 3.04 to 4.24 percent chrysotile. These
products were tested in exposure simulations of six activities related to roof repair: application, wet
sanding, removal from laundered clothing, removal from soiled tools, hand sanding and hand scraping.
Personal (n = 84) and perimeter (n = 49) samples were collected during each 30-min test and analyzed
for total fiber concentration by phase-contrast microscopy (PCM) and for asbestos fiber count by
transmission electron microscopy (TEM). For samples that had detectable asbestos fibers, the total fiber
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9341
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9347
9348
9349
9350
9351
9352
9353
9354
9355
9356
9357
9358
9359
9360
9361
9362
9363
9364
9365
9366
9367
9368
9369
9370
9371
9372
9373
9374
9375
9376
9377
9378
9379
9380
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concentration obtained by PCM was converted to a PCM-equivalent (PCME) asbestos concentration.
EPA used data for the hand sanding and hand scraping activities only, as the other activities involved
wet, uncured product. Sanding and scraping data from Table 4 was averaged to represent the repair of
roofing materials scenario for a DIY user. The average of the reported minimums was used for low end
exposures, the average of the reported arithmetic means was used for central tendency exposures, and
the average of the reported maximums was used for high end exposures. For bystanders, EPA used a
default average RF of 6.
Outdoor, Removal of Roofing Materials: Lange et al. (2008) studied exposure to airborne asbestos
during abatement of ceiling material, window caulking, floor tile, and roofing material at schools in
eastern United States. These commercial abatement activities were considered to provide an adequate
proxy for concentrations encountered during DIY roofing activities. Personal, excursion limit (30
minute), and area (2 hours at perimeter within 10 feet) samples were collected and analyzed by PCM.
All work generally followed OSHA requirements for asbestos. Roofing removal work was performed
without any containment. EPA used personal and perimeter data to evaluate DIY users and bystanders,
respectively. As the results were below the detection limit, the reported detection limit was used for
high-end exposures and one-half of the detection limit was used for central tendency and low-end
exposures.
Indoor, Removal of Plaster: Lange et al. (2008) was also used for indoor removal of plaster. These
commercial abatement activities were considered to provide an adequate proxy for concentrations
encountered during DIY ceiling removal activities. Plaster abatement involved establishment of critical
barriers and full enclosure (plastic sealed over all openings) with a decontamination chamber. For DIY
users, EPA used the personal minimum for low-end exposures, arithmetic mean for central tendency
exposures and maximum for high-end exposures. For bystanders, the results were below the detection
limit, so the detection limit was used for high-end exposures and one-half of the detection limit was used
for central tendency and low-end exposures.
Indoor, Disturbance (Sliding) of Ceiling Tiles: Boelter et al. (2016) studied exposure associated with
maintenance and installation of dropped ceiling systems and lay-in ceiling panels that may have
contained asbestos prior to the late 1970s. The authors conducted two field studies to evaluate exposures
to maintenance workers and bystanders and one chamber study to understand retrospective installation
exposures. As the chamber study was intended to represent historical work scenarios, EPA only used
data from the field studies to evaluate DIY users and bystanders. These commercial maintenance
activities were considered to provide an adequate proxy for concentrations encountered during DIY
ceiling disturbance activities. Bulk ceiling panel samples analyzed by polarized light microscopy (PLM)
found 1 to 4.25 percent amosite and 0.25 to 1.5 percent chrysotile asbestos fibers. In the field studies, an
experienced asbestos abatement worker removed, slid, and replaced ceiling panels and a certified
industrial hygienist (CIH) observed the work. Personal 30-minute and 8-hour TWA samples were
collected for both individuals and analyzed by PCM and TEM. PCME results were calculated by
multiplying the PCM result by the TEM fraction. EPA used the personal 30-minute PCME data from
Table 1 for DIY users and bystanders. As the results were below the quantitation limit, the quantitation
limit was used for high-end exposures and V2 of the quantitation limit was used for central tendency and
low-end exposures.
Indoor, Removal of Ceiling Tiles: Lange et al. (1993) measured asbestos fibers during removal of
asbestos-containing ceiling tiles at a public school in Pennsylvania. After a roof leak from a heavy
rainstorm, saturated ceiling tiles fell to the floor. An abatement containment was established, and the
fallen ceiling tile and remaining in-tact ceiling tile was removed. These commercial abatement activities
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were considered to provide an adequate proxy for concentrations encountered during DIY ceiling
removal activities. Air samples were collected inside and outside the containment on each day of the
abatement activities and were analyzed by PCM or TEM. EPA used the TEM results from Table 1 to
evaluate DIY users. The minimum (detection limit) was used for low end exposures, maximum for high
end exposures and detected mid-point value for central tendency exposures. For bystanders, EPA used a
default average RF of 6.
Indoor, Maintenance (Chemical Stripping, Polishing or Buffing) of Vinyl Floor Tiles: Lundgren et al.
(1991) studied asbestos exposure to workers associated with installation, maintenance, and removal of
vinyl asbestos floor tile. These commercial maintenance activities were considered to provide an
adequate proxy for concentrations encountered during DIY floor tile disturbance activities. Personal and
static (area) samples were analyzed by PCM and scanning electron microscope (SEM). The maintenance
work involved chemical stripping of the existing floor polish, cleaning of the floor tile surface, and then
polishing and buffing of the tile surface; the personal monitoring was performed for 43 minutes. Though
the PCM analysis detected fibers, the SEM analysis found zero quantifiable asbestos fibers (Table 5),
and detection limits were not provided in the study. As the results indicate no evidence of asbestos fiber
release associated with floor tile maintenance work, this scenario is not quantitatively evaluated.
Indoor, Removal of Vinyl Floor Tiles: Lundgren et al. (1991) was also used to evaluate this scenario.
The authors studied both hot and cold removal techniques. Hot removal involved using heat guns to heat
the underlying adhesive and then scrape the tile off, which took 30 minutes. Cold removal involved
using dry ice to freeze the underlying adhesive and then remove the tile, which took 45 minutes. The
authors described the hot removal method as "less destructive," so EPA conservatively used the cold
removal method data to represent consumers. The SEM personal sampling result for cold removal was
used for DIY users and the static sampling result was used for bystanders. As only one value was
reported, this was used to represent all exposures (low-end, high-end, and central tendency).
Flooring Materials, Felt: EPA did not identify monitoring studies measuring asbestos fibers releases
during renovation or disturbance of flooring felt. In the absence of product specific releases during
removal or disturbance activities is not further evaluated for DIY users or bystanders quantitatively and
is evaluated qualitatively by using the indoor removal of vinyl floor tiles as a proxy to assess exposures
and risk.
Indoor, Disturbance Repair (Cutting) of Attic Insulation: Ewing et al. (2010) evaluated asbestos
exposure in homes containing zonolite (expanded vermiculite) attic insulation. Fieldwork was done at
three homes, and a variety of tasks were performed including cleaning storage items or areas in the attic,
cutting a hole in the ceiling below insulation, moving insulation using wet and dry methods and
removing insulation with a shop vacuum. Personal and area air, surface dust and bulk samples were
collected. The amphibole asbestos identified by PLM consisted of tremolite, richterite, winchite and
actinolite. The air samples were analyzed by PCM and TEM, and PCME results were calculated and
reported. EPA used the ceiling cutting task (which took 24 minutes to complete with a drill and hand
saw) to represent the consumer disturbance/repair scenario. The Table 3 personal PCME result was used
for DIY users and an average of three reported area results was used for bystanders. These
concentrations were used to represent all exposures, (low-end, high-end and central tendency).
Indoor, Moving and Removal (With Vacuum) of Attic Insulation: Ewing et al. (2010) was also used to
evaluate this scenario. The moving task consisted of removing insulation from between flooring/floor
joints and using a broom and dustpan to remove debris. This work took 29 minutes to complete. EPA
conservatively used the dry removal method data to represent consumers as wet removal methods
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generally result in lower exposures. For the removal task, insulation from a trough at the perimeter of
the attic was vacuumed, and the vacuum was emptied seven times. This work took 44 minutes to
complete. The Table 5 personal PCME result for the moving task was used for high end exposures, the
Table 6 personal PCME result for the removal task was used for low end exposures, and an average was
used for central tendency exposures for DIY users. The same pattern was followed to develop exposure
concentrations for bystanders, except averages of reported area results were used.
Paper Articles: EPA did not identify monitoring studies measuring asbestos fibers releases during
renovation or disturbance of paper article products. Therefore, this products were not further evaluated
for DIY users or bystanders and is evaluated qualitatively. Based on the finding of fiber releases for
other products within this COU and the potential of these products to release fibers during some activity
that modifies the product, EPA assumes similar exposure and risk patterns.
Subcategory: Filler and Putties
Indoor, Removal of Floor Tile Mastic: The Lange et al. (2008) study that was used for removal of
roofing materials was also used for this scenario. These commercial abatement activities were
considered to provide an adequate proxy for concentrations encountered during DIY mastic removal
activities. Floor tile mastic abatement involved establishment of critical barriers and full enclosure
(plastic sealed over all openings) with a decontamination chamber. EPA used personal and perimeter
monitoring data from Table 1 to evaluate DIY users and bystanders, respectively. As the results were
below the detection limit, the reported detection limit was used for high-end exposures and V2 of the
detection limit was used for central tendency and low-end exposures.
Indoor, Removal of Window Caulking: Lange et al. (2008) was also used for this scenario. These
commercial abatement activities were considered to provide an adequate proxy for concentrations
encountered during DIY caulking removal activities. Caulking removal had a critical barrier enclosure
(plastic sealed over all openings) around windows. EPA used personal and perimeter data from Table 1
to evaluate DIY users and bystanders, respectively. As the results were below the detection limit, the
reported detection limit was used for high-end exposures and V2 of the detection limit was used for
central tendency and low-end exposures.
Indoor, Disturbance (Pole or Hand Sanding and Cleaning) ofSpackle: Rohl et al. (1975) acquired 15
samples of consumer spackling and patching compounds from hardware stores in NYC prior to 1975.
The samples were analyzed by PLM, X-Ray Diffraction (XRD) and TEM to identify asbestos presence.
Three samples contained 5 to 10 percent chrysotile, one contained 4 to 6 percent tremolite and one
contained 10 to 12 percent anthophyllite. The asbestos fibers ranged in length from 0.25 to 8.0 |im, with
shorter than 5 |im in length. The authors measured air concentrations in the breathing zone of drywall
construction workers, and the samples were analyzed by PCM and TEM. The workers performed tasks
including hand sanding, pole sanding, dry mixing and sweeping. Perimeter area samples were also
collected in the same room and adjacent room. The sampling durations were not reported, and "peak
fiber concentration" PCM results of fibers longer than 5 |im were reported. To evaluate consumer
exposures, EPA used data for sanding and sweeping only, as dry mixing is related to installation
activities. The average of the reported minimums was used for low-end exposure, the average of
reported means was used for central tendency exposure, and the average of the reported maximums was
used for high-end exposure. Personal data was used for DIY users and averages of perimeter area data in
the same room and adjacent room was used for bystanders. For low end exposures, the bystander's
minimum concentrations in the same room were greater than the primary worker's concentrations during
sanding activities. This suggests fibers may remain suspended and bystander exposures may not
necessarily always be lower than DIY user exposures.
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Indoor, Disturbance (Sanding and Cleaning) of Coatings, Mastics and Adhesives: Paustenbach et al.
(2004) measured asbestos in air during application, spill cleanup, sanding, removal, and cleaning of
adhesives, coatings and mastics. These products were representative of those produced in the 1960s and
contained 1 to 9 percent chrysotile asbestos. The tasks were performed for 30 minutes, and personal and
area samples were collected and analyzed by PCM and TEM. PCME calculated results were presented
in Table 6 for those samples that had measured asbestos fibers (only sanding, spill cleanup and cleaning
tests had asbestos fibers present; application and removal tests did not have asbestos fibers present). For
DIY users, EPA used the personal sanding concentration for high end exposures and the spill cleanup
concentration for central tendency and low-end exposures. The same pattern was followed for
bystanders with area data.
Subcategory: Solvent-Based/Water-Based Paint
Indoor, Disturbance of Coatings or Textured Paint: Sawyer (1977) studied a ceiling fire- and sound-
retardant coating that was a spray-applied mixture of asbestos and fibrous glass at a Yale school
building. The material gradually deteriorated over time due to normal air movement and vibration and
accidental or intentional contact by maintenance workers. Air sampling was conducted under quiet
conditions and during custodial service, and samples were analyzed by PCM. EPA determined that the
scenarios described in this paper represent indoor air and occupational exposure and are not
representative of a consumer performing an activity that may release friable asbestos fibers from
solvent-based or water-based paint. Additionally, the systematic review process rated the overall study
as low because its description of sampling and analytical methods and approaches lacked sufficient
details. Therefore, this scenario is not further evaluated for DIY users or bystanders.
H.1.2 Furnishing, Cleaning, Treatment Care Products CPU
Subcategory: Construction and Building Materials Covering Large Surface Areas, Including
Fabrics, Textiles, and Apparel
Asbestos textiles including yarn, thread, wick, cord, rope, tubing (sleeving), cloth, tape: EPA did not identify
monitoring studies measuring asbestos fibers releases during renovation or disturbance of textile
products such as yarn, thread, wick, cord, rope, tubing, cloth or tape. Therefore, this products were not
further evaluated for DIY users or bystanders and is evaluated qualitatively. Based on the finding of
fiber releases for other products within this COU and the potential of these products to release fibers
during some activity that modifies the product, EPA assumes similar exposure and risk patterns.
Subcategory: Furniture and Furnishings, Including Stone, Plaster, Cement, Glass, and Ceramic
Articles; Metal Articles; or Rubber Articles
Use of Mittens for Glass Manufacturing, (Proxy for Oven Mittens and Potholders): EPA did not identify
any study related to oven mitts, potholders, or similar products. A United Kingdom study, Cherrie et al.
(2005) assessed asbestos exposures to workers using chrysotile asbestos gloves or mitts in a glass
manufacturing plant. EPA used this data in proxy of oven mittens, potholders and similar products used
as protective clothing for high temperature tasks. In the study, three tasks were observed in conditions
without ventilation and high ventilation. The tasks were rotating a steel pole to row molten glass,
removing, and replacing a glass window, and removing and replacing a side seal. Personal air samples
were collected for 30 minutes for each task which was continuously repeated. The samples were
analyzed by Health & Safety Executive (HSE) Methods for the Determination of Hazardous Substances
(MDHS) 39/4, which is a PCM method. Observations of the tests showed that abrasion of the mitts on
sharp metal edges resulted in the release of airborne dust. EPA determined that the rowing task might be
most applicable to a consumer using oven mitts or gloves and used the rowing data with no ventilation
from Figure 1. The minimum was used for low-end exposures, the maximum was used for high-end
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exposure, and the arithmetic average was used for central tendency exposures for DIY users. For
bystanders, EPA used a default average RF of 6.
H.1.3 Packaging, Paper, Plastic, Toys, Hobby Products CPU
Subcategory: Toys Intended for Children's Use, Including Fabrics, Textiles, and Apparel; or Hard
Plastic Articles
Mineral Kits: EPA did not identify monitoring studies measuring asbestos fibers releases during the
modification of mineral kits nor studies providing asbestos concentrations in these products. Therefore,
this products were not further evaluated for DIY users or bystanders and is evaluated qualitatively.
Based on the description of mineral kits uses in which children and adults scrape, sand, and breakdown
the kits to extract 'gems' or fossils, it is expected that particulate can be uplifted and exposure via
inhalation of asbestos containing particulate occurs.
Coloring of Crayons: Saltzman and Hatlelid (2000) evaluated three brands of children's crayons to
determine whether asbestos was present and to measure children's potential exposure. Crayons were
analyzed by PLM and TEM, and trace amounts of asbestos were found (below detection limit to 0.03
percent). Air samples were collected during a 30-minute simulation of aggressive use, where crayons
were used to draw, shade, and trace with considerable force. Crayons were rubbed and broken to
simulate typical crayon use patterns. The study reported no asbestos fibers were measured during this
simulation, and the authors concluded risk to children is "extremely low".
H.1.4 Automotive, Fuel, Agriculture, Outdoor Use Products COU
Subcategory: Lawn and Garden Care Products
Use of Vermiculite Soil Treatment: U.S. EPA (2000a) measured asbestos from personal breathing zone
air inside a containment (simulating a greenhouse) and personal breathing zone air outdoors during the
use of gardening products that contain vermiculite. This study reported vermiculite concentrations in
gardening products from 2000 and earlier from various sources. In summary, the non-superfund sites
reported non-detects or below detection limits for asbestos concentrations. This product was
reformulated in the early 2000s, and most vermiculite fibers in the product have been subject to
weatherization processes that result in the breakage of fibers to <5 |im in addition to mixing in with
deeper soil layers. EPA concludes that exposure to this product and its legacy use do not pose an
asbestos exposure risk.
H.1.5 Chemical Substances in Products not Described by Other Codes
Subcategory: Other (Artifacts), Vintage Artifacts in Private Collections; Vintage Cars, Articles,
Curios
Metal Dedener: EPA did not identify monitoring studies measuring asbestos fibers releases during
renovation or disturbance or modification of metal deders. Therefore, this products were not further
evaluated for DIY users or bystanders.
H.2 Consumer DIY Exposure Risk Estimate
Consumer and bystander activity-based exposure concentrations and risks were calculated using
EquationApx H-l, which is the general equation for estimating cancer risks for lifetime and less than
lifetime exposure from inhalation of asbestos, from the Office of Land and Emergency Management
Framework for Investigating Asbestos-contaminated Saperfand Sites (U.S. EPA, 2008).
Equation Apx H-l. Equation to Calculate Human Exposure Concentration
Human Exposure Concentration = EPC x TWFLifetime or chronic
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Where:
Raman Exposure Concentration = Lifetime Cancer or non-cancer chronic concentration from
monitoring studies
EPC = Exposure Point Concentration, the concentration of asbestos fibers in air (f/cc) for the
specific activity being assessed
TWF= Time Weighting Factor, this factor accounts for less-than-continuous exposure during a
1-year exposure and is given by:
EquationApx H-2. TWF for Lifetime Cancer Exposure Concentrations
Exposure frequency (-^p-)
365 day
Equation Apx H-3. TWF for Non-cancer Chronic Exposure Concentrations
Exposure duration (yr)~
. Averaging time (yr) .
All of the activity-based scenarios considered people 16 years of age and older for all genders for DIY
users and, and all ages and genders for bystanders. The exposure duration is 62 years for DIY users and
78 years for bystanders, and the Averaging time is 78 years. The non-cancer chronic TWF are calculated
using Equation Apx H-l and are summarized in Table Apx H-l. The values are based on assumptions
related to the activity type (e.g., disturbance/repair or removal) rather than the specific product.
For repair activities, it was assumed that a DIY user may perform one repair or renovation task where
they may disturb ACM per year, and the length of time spent on the task varies for low-end, high-end,
and central tendency exposure estimates. These time estimates are based on professional judgement. For
removal activities, EPA reviewed the frequency of replacement for various home materials such as tiles
and roofing, but also considered the likelihood of consumers encountering legacy use ACM.
For example, while industry experts might recommend replacing floor tile every 20 years, only the first
replacement job is likely to involve removing asbestos-containing floor tile. It is unlikely that newly
installed floor tile that might be replaced again after 20 years would contain asbestos. Therefore, it was
assumed for low-end and central tendency estimates, a DIY user perform removal jobs with asbestos-
containing products once in their lifetime, and for high-end estimates, a DIY user might remove
asbestos-containing products three times over their lifetime. It was assumed that each removal job takes
10 days for central tendency and high-end and estimates and 5 days for low-end estimates. In contrast to
repair activities, it was assumed that removal work takes a longer time (i.e., 8 hours per day).
TWFLifetime ~
tlT
Exposure time
24 hr
x
TWFNon_Cancer chronic ~ X
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9614 Table Apx H-l. Non-cancer Chronic Time Weighting Factors Assumptions for All CPUs
Activity-Based
Scenario
Low- End
TWF
Low-End TWF Basis
High-
End
TWF
High-End
TWF Basis
Central
Tendency
TWF "
Central-
Tendency
TWF Basis
Construction, paint, electrical, and metal products COU: Construction and building materials covering large surface areas
subcategory
Outdoor,
disturbance/repair
(sanding or
scraping) of
roofing materials
0.000045
Assumed 1 repair/year, taking
1 day, lasting 30 min/day
0.00027
Assumed 1
repair/year,
taking 1 day,
lasting 3
lir/day
0.000091
Assumed 1
repair/year,
taking 1 day,
lasting 1
lir/day
Outdoor, removal
of roofing
materials
0.0036
Assumed 1 removal job in
lifetime taking 5 days lasting
8 lir/day
0.022
Assumed 3
removal jobs
in lifetime
taking 10
days lasting
8 lir/day
0.0073
Assumed 1
removal job
in lifetime
taking 10
days lasting
8 lir/day
Indoor, removal of
plaster
0.0036
Assumed 1 removal job in
lifetime taking 5 days lasting
8 lir/day
0.022
Assumed 3
removal jobs
in lifetime
taking 10
days lasting
8 lir/day
0.0073
Assumed 1
removal job
in lifetime
taking 10
days lasting
8 lir/day
Indoor,
disturbance
(sliding) of ceiling
tiles
0.000045
Assumed 1 repair/year, taking
1 day, lasting 30 min/day
0.00027
Assumed 1
repair/year,
taking 1 day,
lasting 3
lir/day
0.000091
Assumed 1
repair/year,
taking 1 day,
lasting 1
lir/day
Indoor, removal of
ceiling tiles
0.0036
Assumed 1 removal job in
lifetime taking 5 days lasting
8 lir/day
0.022
Assumed 3
removal jobs
in lifetime
taking 10
days lasting
8 lir/day
0.0073
Assumed 1
removal job
in lifetime
taking 10
days lasting
8 lir/day
Indoor,
maintenance
(chemical
stripping,
polishing or
buffing) of vinyl
floor tiles
0.000045
Assumed 1 repair/year, taking
1 day, lasting 30 min/day
0.00027
Assumed 1
repair/year,
taking 1 day,
lasting 3
lir/day
0.000091
Assumed 1
repair/year,
taking 1 day,
lasting 1
lir/day
Indoor, removal of
vinyl floor tiles
0.0036
Assumed 1 removal job in
lifetime taking 5 days lasting
8 lir/day
0.022
Assumed 3
removal jobs
in lifetime
taking 10
days lasting
8 lir/day
0.0073
Assumed 1
removal job
in lifetime
taking 10
days lasting
8 lir/day
Indoor,
disturbance/repair
(cutting) of attic
insulation.
0.000045
Assumed 1 repair/year, taking
1 day, lasting 30 min/day
0.00027
Assumed 1
repair/year,
taking 1 day,
lasting 3
lir/day
0.000091
Assumed 1
repair/year,
taking 1 day,
lasting 1
lir/day
Construction, paint, electrical, and metal products COU: fillers and putties subcategory
Indoor,
disturbance (pole
or hand sanding
and cleaning) of
spackle
0.000045
Assumed 1 repair/year, taking
1 day, lasting 30 min/day
0.00027
Assumed 1
repair/year,
taking 1 day,
lasting 3
lir/day
0.000091
Assumed 1
repair/year,
taking 1 day,
lasting 1
lir/day
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Activity-Based
Scenario
Low- End
TWF
Low-End TWF Basis
High-
End
TWF
High-End
TWF Basis
Central
Tendency
TWF "
Central-
Tendency
TWF Basis
Indoor,
disturbance
(sanding and
cleaning) of
coatings, mastics
and adhesives
0.000045
Assumed 1 repair/year, taking
1 day, lasting 30 min/day
0.00027
Assumed 1
repair/year,
taking 1 day,
lasting 3
lir/day
0.000091
Assumed 1
repair/year,
taking 1 day,
lasting 1
lir/day
Indoor, removal of
floor tile/mastic
0.0036
Assumed 1 removal job in
lifetime taking 5 days lasting
8 lir/day
0.022
Assumed 3
removal jobs
in lifetime
taking 10
days lasting
8 lir/day
0.0073
Assumed 1
removal job
in lifetime
taking 10
days lasting
8 lir/day
Indoor, removal of
window caulking
0.0036
Assumed 1 removal job in
lifetime taking 5 days lasting
8 lir/day
0.022
Assumed 3
removal jobs
in lifetime
taking 10
days lasting
8 lir/day
0.0073
Assumed 1
removal job
in lifetime
taking 10
days lasting
8 lir/day
Furnishing, cleaning, treatment care products COU: Construction and building materials covering large surface areas,
including fabrics, textiles, and apparel Subcategory
Use of mittens for
glass
manufacturing,
(proxy for oven
mittens and
potholders)
0.00015
Assumed BBQ' mittens used
more than other hobbies.
People grill on average 1
lir/day, 1 day per week (52
days per year), using an ACM
mitt for 2 years over their
lifetime
0.00076
Assumed
BBQ mittens
used more
than other
hobbies.
People grill
on average 1
lir/day, 1 day
per week (52
days per
year), using
an ACM mitt
for 10 years
over their
lifetime
0.00038
Assumed
BBQ mittens
used more
than other
hobbies.
People grill
on average 1
lir/day, 1 day
per week (52
days per
year), using
an ACM mitt
for 5 years
over their
lifetime
' EPA assumed a cooking or grilling activity-based scenario, which is likely performed in higher frequencies and durations
than other hobbies requiring the need for protective clothing such as mittens and potholders under this COU.
Bolded text in Activity-Based Scenario column highlights product examples for easier finding.
9615
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9616 Appendix I EPIDEMIOLOGIC COHORTS FOR DOSE-RESPONSE
9617 TableApx 1-1 and TableApx 1-2 below provides a summary of each of the epidemiological cohorts for
9618 dose response and the corresponding overall quality determination (OQD) ratings.
9619
9620 Table Apx 1-1. Cohorts Identified for Consideration in Asbestos Part 2 Non-cancer Dose-
9621 Response Analysis
Cohort Name
(Reference^])
Cohort Description
Non-cancer
Outcome(s)
Overall Quality
Determination
(OQD) Rating
IRIS Libby Amphibole Asbestos Assessment, 2014
O.M. Scott Marysville,
OH, Plant Cohort
(Lockev et al.. 1984)
(Rolls et al.. 2008)
• Cohort included 530 workers with known
vermiculite exposure participated in the
1980 investigation. Eight different worksite
operations at the ore processing plant were
represented.
• Monitoring of industrial hygiene at the
facility started in 1972, including personal
breathing zone sampling. PCM
measurements beginning after 1976.
• Job exposure matrix used to determine
cumulative exposures.
• Follow-up including chest x-rays and
interview information from 280 of the 431
workers who were known to be alive
between 2002 and 2005.
• Followed up on the respiratory effects in the
cohort conducted in 2012.
Pulmonary
function
Mortality
Pleural plaques
DPT
Asbestosis
High
Libby, MT,
Vermiculite Mining
and Milling Cohort
• Participants were white men who had
worked for at least 1 year in the mine and
mill.
• Reports based on follow-up data from 1960
to 2006.
• Air sampling data were used to build a job-
exposure matrix assigning daily exposures
(8-hour TWA) for selected job codes.
• Individual work histories and the mine and
mill job-exposure matrix were used to
determine individual exposure metrics.
Mortality
Medium
Cohorts not included in previous EPA assessments for non-cancer effects
SC Textiles Cohort
• Textile plant in Charleston, SC and used
asbestos from 1909 to 1977.
• Original cohort of textile workers limited to
white males employed for at least 1 month
between 1940 and 1965. Later expanded to
included non-whites and females.
• Individual-level exposures estimates
derived from detailed work histories and
extensive air measurements using PCM and
conversion of dust measurements from
analysis of paired sampling.
Mortality
Medium
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Cohort Name
(Reference^])
Cohort Description
Non-cancer
Outcome(s)
Overall Quality
Determination
(OQD) Rating
SC Vermiculite
Miners Cohort
(W. R. Grace & Co.
1988)
• Cohort composed of 194 men hired
between 1949 and 1974 in mining/milling
of vermiculite in Enoree, SC.
• 58 air samples collected in 1986 and
analyzed by PCM.
Mortality,
parenchymal
abnormalities
including pleural
thickening and
sputum analysis
Medium
Anatolia, Turkey,
Villagers Cohort
(Metintas et al.. 2005)
• Field-based, cross-sectional study of 991
villagers from 10 randomly selected
villages with known asbestos-containing
white soil.
• Indoor and outdoor air sample taken for
each village; fibers counted by PCM.
Pleural plaques,
asbestosis,
diffuse pleural
fibrosis
High
Wittenoom, Australia,
Residents Cohort
• Residential cohort included 4659
individuals residing for at least 1 month in
Wittenoom between 1943 and 1992. Mine
workers excluded.
• Follow-up in 1993, 2000, and 2004
• Ambient exposures from nearby crocidolite
assigned based on dates of residence,
assigned exposure intensity, and period
personal monitoring after operations
ceased.
Mortality
Medium
Chinese Chrysotile
Textile Factory
Cohort
(Huane. 1990)
• Cohort of 776 workers employed for at
least 3 years in chrysotile textile product
factory; Shanghai.
• 17 workplaces in the factory selected for
routine sampling; dust and fiber
measurements collected by membrane
filters.
• Follow-up through September 1982 for
asbestos diagnosis.
Asbestosis
incidence
Medium
9622
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9623 TableApx 1-2. Cohorts Identified for Consideration in Asbestos Part 2 Cancer Dose-Response
9624 Analysis
Cohort Name
Cohort Description
Cancer Outcomes"
Overall Quality
Determination (OQD)
Rating
Risk Evaluation for Asbestos Part 1: Chrysotile Asbestos, 2020
NC Textiles
Cohort
• Four textile plants imported raw
chrysotile fibers to make yarns and
woven goods.
• 5,770 workers employed for at least 1
day between 1950 and 1973.
• Cohort followed through 2003.
Mesothelioma,
pleural cancer, lung
cancer
High
SC Textiles
Cohort
• Textile plant in Charleston, SC, and
used asbestos from 1909 to 1977.
• Original cohort of textile workers
limited to white males employed for at
least 1 month between 1940 and 1965.
Later expanded to included non-white
and females.
• Individual-level exposures estimates
derived from detailed work histories
and extensive air measurements using
PCM and conversion of dust
measurements from analysis of paired
sampling.
Lung cancer,
mesothelioma
Medium
Quebec,
Canada
Asbestos
Mines and
Mills Cohort
• Study of chrysotile miners and mill in
Thetford mines in Quebec, Canada.
• The original cohort was made up of
men who were born between 1891 and
1920 and who had worked for at least 1
month in the mines and mills.
• Cohort followed from first employment
in 1904 to May 1992.
• Detail work histories as well as total
dust measurement from 4,000 midget
impinger dust counts in mppcf per year
were analyzed.
Mesothelioma, lung
cancer
Medium
Qinghai, China
Asbestos Mine
Cohort
• Study of chrysotile mine in Qinghai
Province, China.
• Cohort made up of 1,539 male workers
who were on the registry January 1,
1981, and who had worked for at least
1 year.
• Occupational and work history of
cohort was obtained from personnel
records and employee.
• Cohort followed for vital stats from
1981 to 2006.
• Total dust concentrations were
measured by area sampling in fixed
locations and converted to fiber/cc.
Lung cancer,
gastrointestinal
cancer
Medium
Chongqing,
China Asbestos
• Chrysotile asbestos plant in Chongqin,
China, which produces textile, asbestos
Lung cancer
High
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Cohort Name
Cohort Description
Cancer Outcomes"
Overall Quality
Determination (OQD)
Rating
Products
Factory
Cohort
cement products, friction materials,
rubber products and heat-resistant
materials.
• Cohort of 515 men were followed from
January 1, 1972, to December 31, 1996;
workers (men and women) who had
worked for less than 1 year were
excluded.
• Cohort followed until 2008 when
women who were employed between
1970 and 1972 were added to analysis.
• Airborne dust and fiber concentrations
were measured from personal
samplers.
Balangero,
Italy Mining
Cohort
• Balangero mine and mill of the
Amiantifera Company started in 1916
and produced pure chrysotile asbestos.
• Cohort consisted of 1,056 men who
worked in mines for at least 1 year
between January 1, 1930, and
December 31, 1975.
• Cohort followed up from January 1,
1946, or date of first employment, to
December 31, 2003, or when subjects
reached 80 years of age.
• Information on cohort collected from
mine records.
• First fiber counts were first carried out
in 1969 and exposure levels before
1969 were reconstructed to represent
earlier years.
Lung cancer,
laryngeal cancer,
gastrointestinal
cancer,,
mesothelioma
Medium
Salonit
Anhovo,
Slovenia
Asbestos
Factory
Cohort
• Salonit Anhovo factory in western
Slovenia produced asbestos-cement
products made from chrysotile and
amphibole asbestos.
• Cohort made up of 6,714 workers who
had worked for at least 1 day between
1964 and 1994.
• Air sampling measurements taken at
fixed location close to worker's
breathing zone.
• Work histories were obtained from
personnel files.
Lung cancer
Medium
IRIS Libby Amphibole Asbestos Assessment, 2014
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Cohort Name
Cohort Description
Cancer Outcomes"
Overall Quality
Determination (OQD)
Rating
Libby, MT,
Vermiculite
Mining and
Milling
Cohort
• Cohort included 1,871 vermiculite
miners, millers, and processors hired
prior to 1970 and employed for at least
1 year at the Montana site.
• Subjects followed through December
2006.
• Historical air sampling data used to
estimate 8-hour TWA.
• Work histories including job title and
dates of employment were obtained and
used to calculate cumulative fiber
exposures.
Lung cancer,
mesothelioma
Medium (lung cancer)
High (mesothelioma)
IRIS Asbestos Assessment, 1988
US Asbestos
Company
Employees
Cohort
• Cohort consisted of 1,075 men obtained
from company records.
• Subjects were retired between 1941 and
1967 and receiving a pension from
company.
• Cohort followed through 1973.
• Total dust measured in mppcf.
Mesothelioma, lung
cancer, digestive
cancer
Medium
New Orleans
Asbestos
Cement
Building
Material Plants
Cohort
• Includes two asbestos cement building
material plant producing products
containing chrysotile, crocidolite, and
amosite asbestos.
• Cohort consisted of 5,645 men who had
worked in either plant and had at least
20 years of follow up.
• Detail work history obtained from plant
records.
Lung cancer,
mesothelioma,
digestive cancer
High
Ontario,
Canada
Asbestos
Cement
Factory
Cohort
• Cohort included 241 production and
maintenance employees who worked
for at least 9 years at the factory prior
to 1960.
• Impingers were used to prior to 1973
and membranes fiber counts used
thereafter.
• Mortality was followed through
October 1980.
Lung cancer,
mesothelioma,
gastrointestinal
cancer
Medium
NY-NJ
Asbestos
Insulation
Workers
Cohort
• Cohort located in Paterson, NJ, and
manufactured amosite products.
• Cohort included 820 men that worked
for at least 5 years in factory.
• Cohort followed through 1982.
• No fiber counts available, but used
counts for similar plant in Tyler, TX.
Lung cancer
Medium
Asbestos
Textile
Workers
Cohort
• Cohort consisted of white males who
worked at the plant for at least 1 month
prior to January 1, 1959.
• Work histories obtained from this U.S.
textile cohort included all 1,261 white
Lung cancer,
mesothelioma
Medium
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Cohort Name
Cohort Description
Cancer Outcomes"
Overall Quality
Determination (OQD)
Rating
males who worked at the plant for at
least a month between January 1, 1940,
and December 31, 1965. All workers
who had a social security
administration (SSA) record and had
worked for at least 1 month prior to
January 1, 1959, were considered to be
part of the cohort. The cumulative dust
exposures were assigned to each study
participant using the same data that
(Dement et al.. 2008) used to calculate
historical exposures.
International
Association of
Heat and Frost
Insulators and
Asbestos
Workers
Cohort
• Plant located in the NY-NJ metro area
and produced chrysotile and amosite
products between 1943 and 1976.
• Cohort included 623 men employed
prior to 1943 and 833 men employed
after 1943.
• Follow-up in 1962 and 1976.
• Asbestos concentration in facilities not
measured but used counts from other
U.S. insulation facilities that operated
between 1968 and 1971.
Mesothelioma
Medium
Cohort not included in existing EPA assessments
Wittenoom,
Australia,
Residents
Cohort
• Residential cohort included 4,659
individuals residing for at least 1 month
in Wittenoom between 1943 and 1992.
Mine workers excluded.
• Follow-up in 1993, 2000, and 2004.
• Ambient exposures from nearby
crocidolite assigned based on dates of
residence, assigned exposure intensity,
and period personal monitoring after
operations ceased.
Lung cancer, ovarian
cancer,
mesothelioma,
Medium
11 As indicated in Section 1.3 and the Final Scope document, Part 2 of the risk evaluation will focus on mesothelioma
and lung, ovarian, and laryngeal cancers.
9625
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9626 Appendix J TAKE-HOME EXPOSURE DETAILS
9627
9628 3.1 Data Used for Take-Home Analysis
9629 Eight experimental studies were selected for further review; and one study, upon further full-text review, was excluded, leaving seven studies
9630 for use in determining the take-home slope factor. Table Apx J-l below provides the study activity type, job-related loading event
9631 information, take-home exposure event information, and sampling details of the seven studies.
9632
Table Apx J-l. Description of Selected Monitoring Studies o
'Clothes Handling for Take-Home Analysis
Study/Overall Quality
Determination/
Activity Type
Job-Related Loading Event
Take-Home Exposure Event
Sampling Details
Used in regression analysis
(Abelmann et al.. 2017)
Medium
Cutting asbestos
cement pipe (AC)
Description: Cutting asbestos cement (AC)
pipe outdoors using a power saw, simulating
in-ground (trench) and above ground AC
pipe repair in low-wind conditions. Cutting
events were 2 minutes each and the worker
remained in the area for 30 minutes total.
PCME values were not reported.
Description: Unfolding and shaking of 2 sets
of contaminated clothes (2 long sleeve shirts
and 2 jeans) for approx. 1 minute, followed by
no activity, for a total of 30 minutes of
sampling per event (4 separate events).
Min and Max are the lowest and highest event
averages out of 4 events. Avg is the average of
all events.
• Handler: Personal air samples
collected for four 30-minute
clothing shake-out events (n = 4
per event)
• Bvstander: Area air samples
collected for four 30-minute
clothing shake-out events;
samples collected at breathing
zone height, 1.2 m from the
shake-out activity (n = 4 per
event)
• Sampling was performed in a 58
m3 chamber (4.9 m x 4.9 m x 2.4
m) with
• Air changes per hour'1: 3.2
Concentrations: PCM, 30 min
Worker: 5.2 (in-ground) to 12.4 (above
ground) f/cc by PCM (Table 1; assumed
PCM as proxy for PCME). Average is 8.8
f/cc
Concentrations: PCME, 30 min
Handler: (Table 1)
Min: 0.27 f/cc; Avg: 0.52 f/cc; Max: 1.1 f/cc
Bystander: (Table 2)
Min: 0.19 f/cc; Avg: 0.34 f/cc; Max: 0.49 f/cc
(Madl et al.. 2014)
Medium
Vintage maritime valve
repair/ replacement
Description: Complete overhaul of 10
vintage Edward valves manufactured prior
to the 1980s and historically used on
maritime vessels; repair work conducted in
an enclosed room and consisted of replacing
the packing, removing the gasket, and/or
installing a new gasket.
Description: Shaking and folding six
contaminated coveralls for 1-3 minutes (one
for a handler and one for a bystander during
valve repair on three consecutive days, where
new coveralls were used each day, for a total
of 3 worker coveralls and 3 bystander
coveralls). The total sample duration is not
clearly stated but could be presumed to be 16-
36 minutes.
• Handler: Personal breathing zone
samples collected during one
clothes handling event (1-3
minutes per item)
• Center/Bystander/Remote: Area
air samples collected during one
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Study/Overall Quality
Determination/
Activity Type
Job-Related Loading Event
Take-Home Exposure Event
Sampling Details
Concentrations: PCME, 30 min
Worker: 0.013 f/cc (Table 2, all valve
work)
Concentrations: PCME, 30 min
Handler: Avg 0.005 f/cc (Table 2)
Bystander: Avg 0.0015 (taken as one-half the
TEM limit of detection in Table 4)
clothes handling event (1-3
minutes per item)
• Air changes per hour11:
approximately 2-3
(Madl et al.. 2009)
Medium
Brake removal and
repair of heavy
construction equipment
(manufactured between
1960 and 1980)
Description: Brake wear debris released
during brake removal and disassembly from
12 loadcr/backhocs and tractors
manufactured between 1960 and 1980.
Coveralls collected after work completed on
each piece of equipment and stored in
separate plastic-lined bags until clothes
handling task conducted.
Description: Simulated clothes handling task
involved shaking, folding, and turning inside
out 11 sets of contaminated clothing (overalls)
for 1-3 minutes each set (1 event). The total
sample duration is not clearly stated but could
be presumed to be 30 min. Whether the
samples were taken in a chamber is not clearly
stated.
• Breathing zone samples and area
samples at bystander, remote,
and ambient locations
• Air changes per hour'1: 0.6-1.55
Concentrations: PCME, 30 min
Worker: 0.024 f/cc (30 min to 1 hr) by
PCME (Abstract)
Concentrations: PCME, 30 min
Handler: (Table 2)
Min: 0.032 f/cc; Avg: 0.036 f/cc; Max: 0.039
f/cc
Bystander: (Table 2)
Min: 0.003 f/cc; Avg: 0.010 f/cc; Max: 0.018
f/cc
(Madl et al.. 2008)
Medium
Unpacking and
repacking boxes of
brakes for vehicles ca.
1946-80
Description: Unpacking and repacking 105
boxes of automobile brake pads (n = 62) and
shoes (n = 43) for vehicles —1946-80
obtained from vintage automotive parts
suppliers and repair facilities. Coveralls
collected after work completed on each
piece of equipment and stored in separate
plastic-lined bags until clothes handling task
conducted.
Description: Simulated clothes handling task
involved shaking, folding, and turning
coveralls inside out for 1-2 min. Handler
samples are for 15 minutes. Bystander samples
(5 ft from handler) are for 30 minutes.
• Breathing zone samples and area
samples at bystander (1.5 m
from main activity), remote
(7.6-9.1 m from main activity),
and ambient (outside testing
facility) locations
• 30-min sampling duration
• Air changes per hour'1: 0.83 in
2004, 0.39 and 0.66 in 2005
Concentrations: PCME, 30 min
Worker: 0.028 to 0.368 f/cc for handling 4-
20 boxes of brake pads or brake shoes
(abstract). Average of
0.198 f/cc.
Concentrations: PCME, 30 min
Handler: (Table 1, Testing II worker)
Min: 0.007 f/cc; Avg: 0.011 f/cc; Max: 0.015
f/cc
Bystander: (Table 2, bystander)
Avg: 0.010 f/cc based on one detected value
(of 4)
(Jiang et al.. 2008)
Medium
Description: Handling, unpacking, and
repacking 27 boxes of automobile clutch
discs made prior to the mid-1980s provided
Description: Shaking and folding three
different pairs of contaminated overalls for
approx. 45 seconds (1 event). Handler samples
• Bystander (5 ft from main
activity), remote (>50 ft from
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Study/Overall Quality
Determination/
Activity Type
Job-Related Loading Event
Take-Home Exposure Event
Sampling Details
Unpacking/ repacking
or stacking unopened
boxes of automotive
clutch discs
by automotive parts warehouse. Overalls
kept in sealed bag until testing
were collected for two 15-minute intervals and
a 60 minute interval (the first 15-minute
interval was used in this assessment).
Bystander samples (5 ft from handler) were
for 30 minutes.
Avg is average, Max is maximum
main activity), and ambient
(outside testing facility)
locations
• 30-min sampling duration
• Air changes per hour: 0.4, 2.0,
0.3 for 3 days in January
Concentrations: PCME
Worker: 0.026 f/cc (one box, 1 min) to
0.212 f/cc (stacking boxes, 30 min)
(abstract). Average is 0.119 f/cc
Concentrations: PCME
Handler: 1st 15 minutes (Table 4)
Avg: 0.003 f/cc; Max: 0.005 f/cc;
Bystander: 30 minutes (Table 4)
Avg: 0.002 f/cc (taken as one-half the TEM
limit of detection in Table 4)
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Study/Overall Quality
Determination/
Activity Type
Job-Related Loading Event
Take-Home Exposure Event
Sampling Details
(Sahmel et al.. 2014)
Medium
Simulated workplace
and home environments
(sealed chambers);
loading by dust
generator
Description: Chrysotile loading via
aerosolized dust generator at 3 different
target airborne levels (low 0-0.1, medium
1-2, and high 2-4 f/cc); 2 events each level
for 31-43 min
Description: Six 30-minute clothes-handling
and shake-out events (shook for 15 min,
followed by inactivity for 15 min)
• Personal airborne fiber samples
collected during each 15-minute
period of activity or inactivity
and for full 30-minute period
• Four area samples (distances
varied —6-12 ft from handling
activities) collected each 30-
minute handling and shake-out
event at breathing zone height of
~5 ft
• Air changes per hour'1: 13-19
during 30-min events
Concentrations: PCME (SI Table I)
Low: LOD and 0.010; average taken to be
0.005 f/cc; 32 to 45 min sampling
Medium: 1.36 and 3.11 f/cc; average 2.235
f/cc; 34 to 61 min sampling
High: 2.71 and 3.52; average 3.125 f/cc; 37
to 89 min sampling
Concentrations: PCME
Handler: (SI Table II, 15 min)
Low: both events are below LOD; Avg 0.007
(taken as one-half the TEM limit of detection)
Medium: single event 0.094 f/cc (Avg)
High: Event 1: 0.103 fee; Event 2: 0.155 f/cc;
CT: 0.129 f/cc
Bystander: (SI Table III, 30 min)
Low: both events are below LOD; Avg: 0.001
(taken as Vi the TEM limit of detection)
Medium: Event 1 is below LOD; 0.0015 f/cc
(taken as one-half the TEM limit of detection);
Event 2 is 0.006 f/cc; Avg of the two, 0.00375
f/cc.
High: Event 1: 0.006 f/cc; Event 2: 0.013 f/cc;
average of the two, 0.0095 f/cc
(Sahmel et al.. 2016)
High
Simulated workplace
and home environments
(sealed chambers);
loading by dust
generator
Description: Chrysotile loading via
aerosolized dust generator at 1 different
target airborne levels (very high 10 f/cc); 3
different clothing types, 3 garments sets per
type, for two different 6.5 hour loading
events.
Description: Six 45-minute clothes-handling
and shake-out events (shook for 15 min,
followed by inactivity for 30 min)
• Personal airborne fiber samples
collected during 15 min of
shake-out and 30 min post
shake-out activity periods.
• Four area samples (distances
varied 1.8-3.7 m from handling
activities) collected each shake-
out event at breathing zone
height of ~5 ft
• Air changes per hour'1: 3.5
Concentrations: PCME (text, page 51)
Very High: 11.4 f/cc
Concentrations: PCME
Handler: (SI Table B, 0-15 min SO)
Avg: 2.94 f/cc
Bystander: (SI Table C, 45 min)
Avg: 0.62 f/cc
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Study/Overall Quality
Determination/
Activity Type
Job-Related Loading Event
Take-Home Exposure Event
Sampling Details
Not usee
in regression analysis
(Weir etaL 2001)
Low
Arc grinding of brake
shoes
Description: Inspection and replacement of
light-duty vehicle rear drum brakes at an
auto/truck repair facility
Description: Nonrigid freefonn dynamic flow
chamber used to agitate clothing; over 30-min
period clothing was agitated and allowed to
rest for alternating 5-min intervals
Decision to exclude:
1. Uncertainty in how representative the
experimental method (small chamber) is to
real-world samples collected via personal
breathing zone or area samples.
2. Only a single sample was collected.
3. Results only provided for PCM, and the
study notes that asbestifonn was only a small
portion (no quantitative TEM or SEM results
were provided).
• Air samples extracted from
chamber for clothing study
• ACH N/R
• 30-minute sampling duration
" Air changes per hour (ACH) is the process by exchanging the air within a chamber by various means and filters.
9634
9635
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9636
9637
9638
9639
9640
9641
9642
9643
9644
9645
9646
9647
9648
9649
9650
9651
9652
9653
9654
9655
9656
9657
9658
9659
9660
9661
9662
9663
9664
PUBLIC RELEASE DRAFT
April 2024
J.2 Take-Home Exposure Concentration Calculations
The data needed to estimate the yearly average concentration for each scenario using the unit exposure
approach is summarized in Table 5-7 and are explained in EquationApx J-l:
EquationApx J-l. Equation to Calculate Yearly Average Concentration Cancer and Non-cancer
Risk Estimates
Yearly Ave Concert = EPC x
Exposure time
24 hr
x
Exposure frequency (~^r)
365 day
Where:
EPC is Exposure Point Concentration, the concentration of asbestos fibers in air (f/cc) for the specific
activity being assessed. The second term in Equation Apx J-l requires averaging the exposure
concentration over a typical day (resulting in the 24-hour TWA, 24-hour TWA concentration) and over
the number of days a year that exposure occurs expressed in the third term. Based on the approaches
described in Section 3.1.4 and Equation 3-1, Equation Apx J-l turns into Equation Apx J-2 and
Equation Apx J-3, subsequently.
Equation Apx J-2. Equation to Calculate Yearly Average Concentration for Cancer and Non-
cancer Risk Estimates after Slope Factor Approach Substitutions
Yearly Ave Concert = 24/ir TWA Cone x
Exposure frequency (-^p-)
365 day
This exposure concentration is the result from [Y] days of loading a year, where [Y] matches the
occupational scenario frequency:
Equation Apx J-3. Equation to Calculate Yearly Average Concentration for Cancer and Non-
cancer Risk Estimates after Slope Factor Approach and Occupational Frequency Substitutions
Yeary Ave Concen = [X f/cd[ x take-home slope factor x
[Y days]
.365 days.
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9665 J3 Take-Home Risk Estimates for Other Bystander Populations
9666
9667 Table Apx 3-2. Take-Home Inhalation Risk Estimates Summary for All Populations Considered
COUs
OES
Population
Age
Group
Chronic Non-cancer
(Benchmark MOE = 300)
Cancer Lifetime
(Benchmark = 1E-6)
CT
HE
CT
HE
Construction, paint, electrical, and metal
products and.
Furnishing, cleaning, treatment care products
Maintenance, renovation, and demolition
Handler
>16-40a
305,613
88
1.3E-8
4.6E-5
Bystander
>16-40b
480,378
134
84E-9
3.0E-5
Bystander
0-20°
960,756
268
1.3E-8
4.5E-5
Bystander
0-78d
246,348
69
2.1E-8
7.6E-5
Construction, paint, electrical, and metal
products and.
Furnishing, cleaning, treatment care products
Firefighting and other disaster response
activities (career)
Handler
>16-40a
280,146
1,615
14E-8
2.5E-6
Bystander
>16-40b
440,347
2,459
9.2E-9
1.6E-6
Bystander
0-20°
880,693
4,919
9.2E-9
2.5E-6
Bystander
0-78d
225,819
1,261
2.3E-8
4.1E-6
Construction, paint, electrical, and metal
products and.
Furnishing, cleaning, treatment care products
Firefighting and other disaster response
activities (volunteer)
Handler
>16-40a
840,437
4,846
4.8E-9
8.4E-7
Bystander
>16-40b
1,321,040
7,378
3. IE—9
5.5E-7
Bystander
0-20°
2,642,080
14,757
3. IE—9
8.2E-7
Bystander
0-78d
677,456
3,784
7.7E-9
1.4E-6
Construction, paint, electrical, and metal
products
Use, repair, or removal of industrial and
commercial appliances or machinery
containing asbestos
Handler
>16-40a
8,004
47
5. IE—7
8.6E-5
Bystander
>16-40b
12,581
72
3.2E-7
5.6E-5
Bystander
0-20°
25,163
144
3.2E-7
8.5E-5
Bystander
0-78d
6,452
37
8.1E-7
1.4E-4
Construction, paint, electrical, and metal
products.
Furnishing, cleaning, treatment care
products, and
Packaging, paper, plastic, toys, hobby
products
Handling articles or formulations that
contain asbestos (battery insulators, burner
mats, plastics, cured coatings/adhesives/
sealants)
Handler
>16-40a
672
11
6.0E-6
3.7E-4
Bystander
>16-40b
1,057
17
3.8E-6
2.4E-4
Bystander
0-20°
2,114
33
3.8E-6
3.6E-4
Bystander
0-78d
542
9
9.6E-6
6.1E-4
Disposal, including distribution for disposal
Waste handling, disposal, and treatment
Handler
>16-40a
44,823
236
9.1E-8
1.7E-5
Bystander
>16-40b
70,455
360
5.8E-8
1.1E-5
Bystander
0-20°
140,911
719
5.8E-8
1.7E-5
Page 385 of 405
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April 2024
COUs
OES
Population
Age
Group
Chronic Non-cancer
(Benchmark MOE = 300)
Cancer Lifetime
(Benchmark = 1E-6)
CT
HE
CT
HE
Bystander
0-78d
36,131
184
1.4E-7
2.8E-5
Risk values for handlers are less than bystanders for 0-78 age group because handlers have less than lifetime exposure while bystanders have lifetime exposures.
" Scenario representative of garment handler patterns similar to those from occupational durations which is the source of asbestos fibers into clothing.
b Scenario representing people, spouses and others that live at home and are exposed to take-home exposures as bystanders until person and the source of asbestos retires
from their work (source of asbestos in clothing).
c Scenario representative of children living at home while contaminated clothing is handled during their living at home status, 20 years.
J Scenario representing people exposed to take-home exposures at their childhood home from birth and throughout their entire life, whether in the same household or
other with similar take-home exposure possibilities.
9668
Page 386 of 405
-------
9669
9670
9671
9672
9673
9674
9675
9676
9677
9678
9679
9680
9681
9682
9683
9684
9685
9686
9687
9688
9689
9690
9691
9692
9693
9694
9695
9696
9697
9698
9699
9700
PUBLIC RELEASE DRAFT
April 2024
Appendix K DETERMINATION OF LESS-THAN-LIFETIME
INHALATION UNIT RISK (IUR) VALUES
This appendix provides a description on the sources of information and approaches used to obtain the
less-than4ifetime (LTL) IUR values used in this draft Asbestos Part 2 Risk Evaluation. There are two
main sources of LTL values:
1. The LTL numbers for the 1988 IUR are here:
a. Framework for Investigating Asbestos-Contaminated Comprehensive Environmental
Response, Compensation and Liability Act Sites framework for Investigating Asbestos-
Contaminated Comprehensive Environmental Response, Compensation and Liability Act
Sites (see Table H-4).
2. The LTL IUR value for the Asbestos Part 1 Risk Evaluation is provided in this appendix.
There are no LTL numbers for Libby Amphibole Asbestos (LAA).
Recommended estimates of the LTL values for Part 2 are the mean of the 1988 LTL values and the
Asbestos Part 1 LTL values for the specific age at first exposure and the duration of exposure
combinations, rounded up to two significant digits to be protective of public health.
The lifetime exposure scenario already has an IUR or 0.2 per f/cc.
• Scenarios considered under the draft Asbestos Part 2 Risk Evaluation were for first exposure at
birth and then 20 years of duration to represent a child bystander growing up in a contaminated
home (e.g., general population): IUR(o.20);
• First exposure at birth, duration for 1 year, and carried on through a lifetime for general
population exposed to asbestos from non-stationary activity-based releases (e.g., general
population): IUR(o.i)
• First exposure at age 16 years and then 40 years of duration (both occupational exposure, and
take-home scenarios): IUR(i6.40); and
• First exposure at age 16 years and then 62 years of duration (consumer exposure scenarios):
IUR(i6 .62).
• Other LTL IURs were used to perform a sensitivity analysis for the stationary releases of
asbestos and exposures to the general population: IUR(2o.io), IUR(20.30), IUR(3o.io)
Table Apx K-l. Less-than-Lifetime (LTL) IURs for Asbestos: Part2
Age at First Exposure
(years)
Duration
(years)
1988 LTL IUR
(per f/cc)
Part 1 LTL IUR
(per f/cc)
Part 2 LTL IUR
(per f/cc)
0
1
0.01
0.00414
0.01
0
20
0.14
0.106
0.12
16
10
0.045
0.0292
0.04
16
20
0.072
0.0468
0.06
16
40
0.098
0.0612
0.08
16
62
0.11
0.0641
0.09
20
10
0.039
0.0235
0.03
20
30
0.075
0.0448
0.06
30
10
0.026
0.0132
0.02
Page 387 of 405
-------
9701
9702
9703
9704
9705
9706
9707
9708
9709
9710
9711
9712
9713
9714
9715
PUBLIC RELEASE DRAFT
April 2024
EPA compared risk estimate results (i.e., ELCR values) using lifetime and LTL (U.S. EPA. 1988b)
IURs and Part 2 IUR values, see TableApx K-l. The comparison results are available in a series of
tables for each population assessed in this Part 2 risk evaluation: workers, take-home, DIYers, and the
general population. If the calculated ELCR is greater than the benchmark ELCR (1 x 10~6), this is a
starting point to determine if there are unreasonable cancer risks. A comparison of IUR ELCR values
relative to the benchmark values derived from (U.S. EPA. 1988b) and the Part 1 risk evaluation is
provided in Table Apx K-2 to Table Apx K-5. The summary tables below mark with a red "x" those
that where above the benchmark for one IUR and below the benchmark for the other. Differing ELCR
values only resulted from one high end take-home scenario corresponding to Firefighting and Other
Disaster Response Activities (Volunteer) OES; one below the benchmark when using the 0.08 LTL IUR
value and above the benchmark when using the 0.098 LTL IUR value. The ELCR value that was
calculated with a 0.08 IUR was close to the benchmark and an 18 percent difference between the LTL
IUR values resulted in an ELCR values over the benchmark. However, benchmark values are not the
only indicators used to determine if there is risk or unreasonable risk.
Table Apx K-2. Occupational Part 1 and Part 2 IUR ELCR Comparison
Chronic, Cancer
Occupational Exposure Scenario (OES)
Significant Exposure
Exposure
Exposures (8-hr TWA)
ELCR IUR Comp.
Group (SEG)
Scenario
HE ELCR
CT
ELCR
Comp.
Comp.
Higher-Exposure Workers
8-hr
V
V
Handling asbestos-containing building materials
during maintenance, renovation, and demolition
activities
Lower-Exposure Workers
8-hr
V
V
ONU
8-hr
V
V
Higher-Exposure Workers
30-min
V
V
Lower-Exposure Workers
30-min
V
V
ONU
30-min
V
V
Handling asbestos-containing building materials
Higher-Exposure Workers
8-hr
V
V
during firefighting or other disaster response
activities
Lower-Exposure Workers
8-hr
V
V
Use, repair, or removal of industrial and
Higher-Exposure Workers
8-hr
V
V
commercial appliances or machinery containing
ONU
8-hr
V
V
asbestos
Higher-Exposure Workers
30-min
V
V
Higher-Exposure Workers
8-hr
V
V
Lower-Exposure Workers
8-hr
V
V
Handling articles or formulations that contain
ONU
8-hr
V
V
asbestos
Higher-Exposure Workers
30-min
V
V
Lower-Exposure Workers
30-min
V
V
ONU
30-min
V
V
Waste handling, disposal, and treatment
Higher-Exposure Workers
8-hr
V
V
ONU
8-hr
V
Comparison matrix results: Red "x" are those that one ELCR result exceeds the benchmark while the other does not, check
marks are both IUR ELCR estimates are either above or below the benclunark
Page 388 of 405
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PUBLIC RELEASE DRAFT
April 2024
9716 Table Apx K-3. Take-Home Part 1 and Part 2 IUR ELCR Comparison
Scenario/OES
Handler Less Than Lifetime
ELCR (16,40)
Bystander Lifetime
" ELCR (0,78)
CT ELCR Comp.
HE
ELCR
Comp.
CT
ELCR
Comp.
HE
ELCR
Comp.
Maintenance, renovation, and demolition
V
V
V
V
Firefighting and other disaster response activities (career)
V
V
V
V
Firefighting and other disaster response activities (volunteer)
V
V
V
X
Use, repair, or removal of industrial and commercial appliances
or machinery containing asbestos
V
V
V
V
Handling articles or formulations that contain asbestos (battery
insulators, burner mats, plastics, cured
coatings/adhesives/sealants)
V
V
V
V
waste handling, disposal, and treatment
V
V
V
V
Comparison matrix results: Red "x" are those that one ELCR result exceeds the benchmark while the other does not, check
marks are both IUR ELCR estimates are either above or below the benclunark
9717
9718 Table Apx K-4. Consumer DIY Part 1 and Part 2 IUR ELCR Comparison
cou
Subcategory
Product and Activity-Based Scenario
LE
ELCR
Comp.
CT
ELCR
Comp.
HE
ELCR
Comp.
Chemical
substances in
construction,
paint, electrical,
and metal
products
Construction and
building
materials
covering large
surface areas
Outdoor, disturbance/repair (sanding or scraping) of
roofing materials
V
V
V
Outdoor, removal of roofing materials
V
V
V
Indoor, removal of plaster
V
V
V
Indoor, disturbance (sliding) of ceiling tiles
V
V
V
Indoor, removal of ceiling tiles
V
V
V
Indoor, maintenance (chemical stripping, polishing
or buffing) of vinyl floor tiles
V
V
V
Indoor, removal of vinyl floor tiles
V
V
V
Indoor, disturbance/repair (cutting) of attic
insulation.
V
V
V
Indoor, moving and removal with vacuum of attic
insulation
V
V
V
Fillers and
putties
Indoor, disturbance (pole or hand sanding and
cleaning) of spackle
V
V
V
Indoor, disturbance (sanding and cleaning) of
coatings, mastics and adhesives
V
V
V
Indoor, removal of floor tile/mastic
V
V
V
Indoor, removal of window caulking
V
V
V
Chemical
substances in
furnishing,
cleaning,
treatment care
products
Construction and
building
materials
covering large
surface areas,
including fabrics.
Use of mittens for glass manufacturing, (proxy for
oven mittens and potholders)
V
V
V
Page 389 of 405
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PUBLIC RELEASE DRAFT
April 2024
cou
Subcategory
Product and Activity-Based Scenario
LE
ELCR
Comp.
CT
ELCR
Comp.
HE
ELCR
Comp.
textiles, and
apparel
Comparison matrix results: Red "x" are those that one ELCR result exceeds the benchmark while the other does not, check
marks are both IUR ELCR estimates are either above or below the benclunark.
Bystander results look the same as DIYer, see Supplemental file Asbestos Part 2 Draft RE - Risk Calculator Consumer -
Fall 2023.
9719
Page 390 of 405
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PUBLIC RELEASE DRAFT
April 2024
9720 Table Apx K-5. General Population Part 1 and Part 2 IUR ELCR Comparison
OES
COU(s)
Distance from the Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
Low-end tendency lifetime cancer ELCR (f/cc) (benchmark = 1E-06)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution for disposal
V
V
V
V
V
V
V
V
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive h
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
V
V
V
V
V
V
V
V
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical, and metal
products
V
V
V
V
V
V
V
V
Handling articles or formulations
that contain asbestos fugitive "
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
COU: Packaging, paper, plastic, toys, hobby products
V
V
V
V
V
V
V
V
Central tendency lifetime cancer ELCR (benchmark = 1E-06)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution for disposal
V
V
V
V
V
V
V
V
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive h
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
V
V
V
V
V
V
V
V
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive b
COU: Construction, paint, electrical, and metal
products
V
V
V
V
V
V
V
V
Handling articles or formulations
that contain asbestos fugitive "
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
COU: Packaging, paper, plastic, toys, hobby products
V
V
V
V
V
V
V
V
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive h
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
V
V
V
V
V
V
V
V
High-end tendency lifetime cancer ELCR (f/cc) (benclunark = 1E-06)
Waste handling, disposal, and
treatment fugitive"
COU: Disposal, including distribution for disposal
V
V
V
V
V
V
V
V
Page 391 of 405
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April 2024
OES
COU(s)
Distance from the Source (m)
10
30
60
100
100-1,000
2,500
5,000
10,000
Handling asbestos-containing
building materials during
maintenance, renovation and
demolition activities fugitive b
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
V
V
V
V
V
V
V
V
Use, repair, or disposal of
industrial and commercial
appliances or machinery
containing asbestos fugitive h
COU: Construction, paint, electrical, and metal
products
V
V
V
V
V
V
V
V
Handling articles or formulations
that contain asbestos fugitive "
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
COU: Packaging, paper, plastic, toys, hobby products
V
V
V
V
V
V
V
V
Handling asbestos-containing
building materials during
firefighting or other disaster
response activities fugitive b
COU: Construction, paint, electrical, and metal
products
COU: Furnishing, cleaning, treatment care products
V
V
V
V
V
V
V
V
a The lifetime cancer risk exposure duration is 20 years which is the number of years residents are assumed to reside in a single residential location for stationary OES.
The exposure starting age is zero (birth) to consider highly exposed and sensitive population. The Averaging time for exposure years is 78 years representing the number
of vears an individual is assumed to live (Exposure Factors Handbook. (U.S. EPA. 2011)).
h The lifetime cancer risk exposure duration is 1 year for non-stationary OES which is the smallest available IUR value.
Comparison matrix results: Red "x" are those that one ELCR result exceeds the benchmark while the other does not, check marks are both IUR ELCR estimates are
either above or below the benclunark.
9721
Page 392 of 405
-------
9722
9723
9724
9725
9726
9727
9728
9729
9730
9731
9732
9733
9734
9735
9736
9737
9738
9739
9740
9741
9742
9743
9744
9745
9746
9747
9748
9749
9750
9751
9752
9753
9754
9755
9756
9757
9758
9759
9760
9761
9762
9763
9764
9765
9766
9767
PUBLIC RELEASE DRAFT
April 2024
Appendix L GENERAL POPULATION
The general population exposure concentrations and inhalation lifetime cancer risk are calculated using
EquationApx L-l and EquationApx L-2. Lifetime cancer and non-cancer chronic risk estimates are
available in Asbestos Part 2 Draft RE - Risk Calculator for Consumer - Fall 2023 (U.S. EPA. 2023k)
(see Appendix C).
Equation Apx L-l. Equation to Calculate Excess Lifetime Cancer Risk
Where:
ELCR
EPC
IF
IURLifetime or LTL
TWF
ELCR — EPC x IF x TWF x IURLifetime or ltl
Excess Lifetime Cancer Risk, the risk of developing cancer as a
consequence of the site-related exposure
Exposure Point Concentration, the concentration of asbestos fibers
in air (f/cc) for the specific activity being assessed
Infiltration factor, 0.5
Inhalation Unit Risk per f/cc for Lifetime or Less-Than-Lifetime
(LTL). Various LTL IUR values were used, IUR(o.i), IUR(0.20),
IUR(20.30), and IURLifetime (IUR(0,78))
Time Weighting Factor that accounts for less-than continuous
exposure during a one-year exposure or a lifetime exposure
Equation Apx L-2. Equation to Calculate TWF for Lifetime Cancer
TWFiifetime or ltl —
Exposure time (hr/day)
24 hours
x
Exposure frequency (day/yr)
365 days
Where:
Exposure time =
Exposure frequency =
15.8 hr/day for CT and LE and 23.8 hr/day for HE scenarios
365 day/yr.
The Exposure time parameters were taken from EPA's Exposure Factors Handbook (U.S. EPA. 2011).
Table 16-1, using the 18 to 65 group age indoor spending time value provided in that table. The mean
was used for central (CT) and low-end (LE) tendency scenarios, and 95th percentile was used for the
high-end (LE) tendency scenarios. EPA assumes the general population scenario is for indoor exposures
for people living at certain distance from the asbestos releases. In addition, EPA assumes the inside
asbestos concentration is the same as outside. An infiltration factor can be used, but generally these can
be influenced by air change rates, window opening behaviors, ventilation systems, house cleaning
behaviors among other factors that would result in high variability and uncertainty. Assuming the
concentration inside and outside are the same will result in overestimation of risk, but it will also
represent the high exposure populations.
The non-cancer chronic risk, also known as the MOE is calculated via Equation Apx L-3.
Equation Apx L-3. Equation to Calculate Non-cancer Chronic Margin of Exposure
Point of Departure (POD)
MOE
Non-Cancer Chronic ~
Non — Cancer Chronic Exposure Concentration
Page 393 of 405
-------
9768
9769
9770
9771
9772
9773
9774
9775
9776
9777
9778
9779
9780
9781
9782
9783
9784
9785
9786
9787
9788
9789
9790
9791
9792
9793
9794
9795
9796
9797
9798
9799
9800
9801
9802
9803
9804
9805
9806
9807
PUBLIC RELEASE DRAFT
April 2024
The POD is discussed in Section 5.2.2.1. The non-cancer chronic ambient air inhalation exposure
concentration is calculated using the concentration from the AERMOD modeling efforts described in
Section 3.3.1.3, Table 3-11, and using EquationApx L-4.
EquationApx L-4. Equation to Calculate Non-cancer Chronic Concentration (NCCC) for
Ambient Air Inhalation Pathway
NCCC = Ambient Air Cone x IF x
Exp time Exp freq ED
x
x
Where:
NCCC
Ambient Air Cone
IF
Exp time
Exp freq
ED
AT
24 hr 365 day AT
Non-cancer chronic concentration for general population ambient
air inhalation pathway
AERMOD modeled concentration for ambient air in Section
3.3.1.3 and Table 3-11
Infiltration factor, 0.5
Exposure time in hours per day is equal to 15.8 hr/day for CT and
23.8 hr/day for HE
Exposure frequency in days per year equal to 365 day/yr
Exposure duration, 1, 20, 30, and 78 years, short duration
activities/releases, children residential duration, adult residential
duration, and lifetime exposures, respectively
Averaging time for exposure years is 78 years representing the
number of years a person is assumed to live (U.S. EPA. 2011).
The first three terms in Equation Apx L-4 are the concentrations summarized in Section 3.3.1.3, Table
3-11, and the TWFLifetimeorLTL used for the calculation of ELCR. The only difference is the ED and AT
terms which are not in the calculation of ELCR because these are already included in the calculation of
IURs.
Additional exposure durations (ED) and less-than-lifetime (LTL) IUR lifetime cancer and non-cancer
chronic risk estimates were calculated to compare risk estimates. TableApx L-l and TableApx L-2
summarize the comparison of lifetime cancer (ELCR) risk estimates with multiple LTL IUR values, and
non-cancer chronic (MOE) risk estimates with multiple ED values, respectively.
ED and LTL IUR (0,20) considers exposures starting at birth and ending at 20 years of age and carrying
it throughout a person's entire lifespan, 78 years. Twenty years is an expert opinion and assumption
when most children move from their childhood residences. ED and LTR (20,30) considers exposures
starting at 20 years and ending 30 years later (50) and carrying it throughout a person's entire lifespan,
78 years. This (20,30) scenario considers young and mature adults that move out of their childhood
residence and remain in their next residence for 30 years. The lifetime (0,78) considers people that
remain at their childhood residence throughout their entire lifespan, 78 years.
Page 394 of 405
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9808 Table Apx L-l. Lifetime Cancer Risk Estimate Comparison for Various LTL IUR Values
LE/ CT / HE
Distance from
Release Source
(m)
ELCR Using IUR (0,20)
ELCR Using IUR (20,30)
ELCR Using IUR (Lifetime (0, 78)
Waste Handling
Handling Articles
and Formulations
Waste Handling
Handling Articles
and Formulations
Waste Handling
Handling Articles
and Formulations
LE
10
1.3E-4
2.0E-5
7.7E-5
1.2E-5
2.6E-4
4.1E-5
30
1.7E-5
1.4E-5
1.0E-5
8.2E-6
34E-5
2.7E-5
60
3.4E-6
1.3E-5
2.0E-6
7.8E-6
6.8E-6
2.6E-5
100
94E-7
1.2E-5
5.6E-7
7.3E-6
1.9E-6
2.4E-5
CT
10
3.0E-4
3.0E-5
1.8E-4
1.8E-5
6.0E-4
6.0E-5
30
5.1E-5
1.6E-5
3.1E-5
94E-6
1.0E-4
3.1E-5
60
1.2E-5
1.3E-5
7.0E-6
8.1E-6
2.3E-5
2.7E-5
100
3.5E-6
1.3E-5
2.1E-6
7.7E-6
6.9E-6
2.6E-5
HE
10
8.6E-4
8.2E-5
5.2E-4
4.9E-5
1.7E-3
1.6E-4
30
1.8E-4
3.2E-5
1.1E-4
1.9E-5
3.6E-4
6.3E-5
60
44E-5
2.2E-5
2.7E-5
1.3E-5
8.8E-5
4.5E-5
100
14E-5
2.1E-5
8.1E-6
1.2E-5
2.7E-5
4.1E-5
Highlighted cells indicate benchmark exceedances, ELCR benchmark = 1E10-06
9809
9810 Table Apx L-2. Non-cancer Chronic Risk Estimate Comparison for Various ED Values
LE/ CT/ HE
Distance from
Release Source
(m)
ELCR Using IUR (0,20)
ELCR Using IUR (20,30)
ELCR Using IUR (Lifetime (0, 78)
Waste Handling
Handling Articles
and Formulations
Waste Handling
Handling Articles
and Formulations
Waste Handling
Handling Articles
and Formulations
LE
10
79
498
53
332
79
498
30
604
740
403
493
604
740
60
2,992
785
1,995
523
2,992
785
100
10,791
829
7,194
553
10,791
829
CT
10
34
337
23
225
34
337
30
199
650
133
433
199
650
60
865
756
576
504
865
756
100
2,918
795
1,946
530
2,918
795
HE
10
12
123
8
82
12
123
30
57
320
38
214
57
320
60
229
453
153
302
229
453
100
751
494
500
329
751
494
Highlights cells indicate benchmark exceedances, MOE benchmark = 300
9811
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Appendix M AGGREGATE ANALYSIS
Section 5.1.5 describes the approach to aggregate exposures in the draft Part 2 Risk Evaluation of
Asbestos. As described in Section 5.1, EPA considered sentinel exposures by considering risks to
populations who may have upper bound exposures; for example, workers and ONUs who perform
activities with higher exposure potential, or consumers who have higher exposure potential (e.g., those
involved with DIY projects). EPA characterized high-end exposures in evaluating exposure using both
monitoring data and modeling approaches. Where statistical data are reasonably available, EPA typically
uses the 95th percentile value of the reasonably available data set to characterize high-end exposure for a
given condition of use. For consumer and bystander exposures, EPA characterized sentinel exposure
through a "high-intensity use" category based on both product and user-specific factors. In cases where
sentinel exposures result in MOEs or ELCRs greater than the benchmark or cancer risk lower than the
benchmark (i.e., risks were not identified), EPA did no further analysis because sentinel exposures
represent the highly exposed. The aggregate analysis across exposure scenarios and COUs figures and
summaries are available in Asbestos Part 2 Draft RE - Aggregate Analysis - Fall 2023 (U.S. EPA.
2023a) (see Appendix C).
This analysis only aggregates individual risk estimates from scenarios that were not above the
benchmark and assumes the possibility of people engaging in the scenario activities being aggregated. In
addition, EPA aims to identify not random combinations but within the central tendency (CT) and high-
end (HE) tendencies what kind and number of non-occupational and occupational activities are needed
in the aggregation to exceed benchmarks.
Lifetime Cancer Risk Aggregate Analysis across Exposure Scenarios
A worker may be involved in multiple activities aside from their work requirements that exposes them to
asbestos that have varying occupational exposures. DIYers may perform multiple projects that release
and exposes them to asbestos fibers. Take-home exposures can occur to workers and DIYers as they
handle asbestos-contaminated clothing and do non-occupational renovation activities. Higher-exposure
workers 8-hour TWA lifetime cancer risk values (ELCR) are above the benchmark for a few scenarios
for the HE and CT tendencies, which are not used in the aggregate analysis, see Table 5-21. EPA only
aggregated across scenarios if the ELCR values for each scenario are below the non-occupational
benchmark (1 x 10~6 f/cc).
Because very few HE ELCR values can be used in this aggregate analysis, EPA shows some examples
of aggregation across scenarios for CT ELCR values in Figure Apx M-l. EPA used unique parts of the
OES labels and the general population distance from the release activity (source of the release) to fit the
figure. The OES can then be linked to the COUs in the discussion below each figure.
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1.2E-06
1.0E-06
PUBLIC RELEASE DRAFT
April 2024
i Take-Home Garment Handler
DIYer Disturbance Ceiling Tiles
¦DIYer Disturbance Outdoor Roof
—Benchmark 1E-6
DIYer Indoor Disturbance Fillers
& 8.0E-07
O
i—J
w
g 6.0E-07
U 4.0E-07
2.0E-07
0.0E+00
Maintenance, Renovation, Firefighting and Other Firefighting and Other Use, Repair, or Removal of Waste Handling, Disposal,
and Demolition Disaster Response Activities Disaster Response Activities Industrial and Commercial and Treatment
(Career) (Volunteer) Appliances or Machinery
FigureApx M-l. Central Tendency Lifetime Cancer Risk Aggregation across Take-Home and
DIY Scenarios
Figure Apx M-l shows the combined CT ELCR risks (vertical axis) for take-home exposures resulting
from various occupational activities (horizontal axis and blue bar) and those same people doing DIY
activities (non-blue bars). The DIY activities used in this aggregation are related to disturbance of
asbestos materials, such as sanding, cutting, moving, because activities related to removing or
demolishing asbestos were already above the risk benchmark on their own. People exposed to take-
home removal/repair of appliances/machinery exposures combined with DIY activities related to the
disturbance of products result in over the risk benchmark for lifetime cancer risk.
1.60E-06
^ 1.40E-06
o
(J
S. 1.20E-06
Pi
hJ 1.00E-06
W
I" 8.00E-07
S 6.00E-07
H
2 4.00E-07
a
U
2.00E-07
0.00E+00
Demolition
Firefighting
Career
Firefighting
Volunteer
^ ^
\Q
Removal Machinery
Waste
Handling
fa5* ^ ^ ^
K? A? ^
¦General Population Ambient Air
DIYer Indoor Disturbance Fillers
General population distance from release activity (m)
¦Take-Home Garment Handler
¦DIYer Disturbance Ceiling Tiles
¦ DIYer Disturbance Outdoor Roof
—Benchmark 1E-6
Figure Apx M-2. Central Tendency Lifetime Cancer Risk Aggregation across Take-Home,
DIYers, and General Population Risks to Occupational Activities Releases to Ambient Air
Scenarios
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April 2024
FigureApx M-2 shows the combined CT ELCR (vertical axis) values for people living at a distance
from various occupational activity releases (horizontal axis and blue bars) as well as those same people
doing DIY activities (lighter blue bars) and exposures from take-home (orange bars). This aggregate
analysis builds upon Figure Apx M-l analysis adding general population to it. This aggregate scenario
aims to show all non-occupational populations and which activities drive the aggregation to above the
following benchmark values:
• People living within 30 m from demolition activities, performing DIY activities, and handling
contaminated garments from demolition activities may have aggregate risks of concern the closer
they are to the activity (see demolition box in Figure Apx M-l).
• People performing removal/maintenance of machinery/appliances activities, DIY activities, and
handling contaminated garments (from removal machinery activities) may have aggregate risks
of concern (see removal machinery box in figure) and increase risk probabilities by proximity to
the activity.
2.00E-06
o
g, 1.50E-06
0
W
g 1.00E-06
0)
£
1 5.00E-07
-------
9898
9899
9900
9901
9902
9903
9904
9905
9906
9907
9908
9909
9910
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April 2024
Lifetime Cancer Risk Aggregate Analysis across COUs
FigureApx M-4 shows aggregation across COUs for LE, CT, and HE ELCR values (boxes in figure)
and people living at a distance from an occupational activity release (horizontal axis within boxes) and
high-exposure workers and CT take-home (outside boxes). EPA did not include DIYers in this
aggregation because only a few scenarios were below the risk benchmark for HE, CT, and LE
tendencies and all are from the same COU. Aggregation of DIY lifetime risks is available in aggregation
across scenarios in Figure Apx M-l. Each of the scenarios has a number in parentheses representing the
number of OESs in the aggregation that were not individually above the risk benchmark. A total of six
OESs can be aggregated. Activities that drive the aggregation above the benchmark are related to
workers performing activities related to demolitions, maintenance, renovations and firefighting or other
disasters, see LE, CT, and HE boxes with various bars close or above the benchmark line.
1.60 E-06
1.40 E-06
ig 1.20 E-06
Pi
u
^ 8.00E-07
O 6.00E-07
S
2 4.00E-07
2.00E-07
0.00E+00
I
.
Low-End Tendency General
Population ELCR
I
^ ^ ^ ^
4 ^ ^%^//// *
Central Tendency General
Population ELCR
I.I
^ ^ ^ ^ ^
High-End Tendency General
Population ELCR
v3 v
^¦Demolition, Renovation, Maintenance
^¦Removal / Repair Machinery
Benchmark
General population distance from release activity (m)
¦ Firefighting / Disaster Career
¦ Handling articles or formulations
¦Firefighting / Disaster Volunteer
¦Waste Handling
Figure Apx M-4. Lifetime Cancer Risk Aggregation across COUs for General Population, Take-
Home Exposures and High-Exposure Workers
Parenthesis in the horizontal axis are the number of COUs in the specific aggregation scenario. There are a total of
six (6) COUs if not included in the aggregation the COU exceeded the benchmark before aggregation.
Non-cancer Chronic Risk Aggregate Analysis Across Scenarios
Figure Apx M-5 shows the combined LE, CT, and HE non-cancer chronic risks (vertical axis) for
DIYers only. This aggregate analysis assumes that a DIYer in their lifetime can perform multiple
projects that are captured in the DIY aggregate scenario. The first three bars combine all DIY activities
that are individually under the benchmark for construction materials COU only, excluding potholders
which belong to the furnish products COU last two bars.
• The majority of the high-end DIY scenarios resulted in MOE values over the benchmark and are
not used in the aggregation so very few activities are aggregated in the third bar. Only three high-
end DIYer activities are used in this aggregation because they are individually below the risk
benchmark and correspond to disturbance of products rather than removal activities (third bar in
figure).
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• All activities related to removal of a product when aggregated resulted in individual activities
over the risk benchmark (not shown in figure). If all product removal activities are taken out of
the aggregation and only disturbance (cutting, sanding, moving) of product are left, the results
show aggregated risk for disturbance of insulation and spackle (LE disturbance of construction
and furnishing products bar in figure).
• An only DIYer aggregate analysis for all DIY scenarios under the MOE benchmark shows that
for a DIYer that performs all activities at the low-end tendency will result in over the benchmark
risks (first bar in figure).
1.0E-02
8.0E-03
g 6.0E-03
te
LU
O
§ 4.0E-03
2.0E-03
O.OE+OO
LE Construction Materials CT Construction Materials HE Construction Materials
and Furnishing Products
iDIYer Outdoor Disturbance Roof
DIYer Disturbance Ceiling Tiles
¦DIYer Disturbance Attic Insulation
iDIYer Indoor Removal Fillers
Products Products
¦DIYer Outdoor Removal Roof
¦ DIYer Removal Ceiling Tiles
¦ DIYer Disturbance Spackle
¦ Potholder
LE Disturbance of
Construction and
Furnishing Products
CT Disturbance of
Construction Products
¦DIYer Plaster Removal
¦DIYer Removal Vinyl Floor Tiles
¦DIYer Indoor Disturbance Fillers
—Benchmark
FigureApx M-5. Non-cancer Chronic Risk Aggregate across DIY Activities
FigureApx M-6 shows the combined CT and LE non-cancer chronic risks for people living at a
distance from an occupational release activity (horizontal axis and boxes in figure), take-home (orange
bar) and DIYers (all other bars). The HE MOE values for most of the individual activities considered
and the exposed populations were above the benchmark and hence not used. When calculating aggregate
risk for DIYers, EPA included only the disturbance of product DIY activities which are the only ones
that do not individually above the risk benchmark. None of the aggregated activities resulted in over the
benchmark risks indicating that it likely requires HE tendencies to result in non-cancer chronic risks.
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9947
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9951
9952
9953
9954
9955
9956
9957
9958
9959
9960
9961
9962
9963
9964
9965
~ 2.50E-03
O
2
.2 2.00E-03
V 1.00E-03
a
c
%
Demolition
Repair Machinery
N? ^ ^ ^ ^
> a s
^ <0* ^ ^ ^
Handling Articles or Formulations
to* s# ^ ^ ^
Waste Handling
¦f /
General populatin distance from release activity (m)
¦LE General Population Ambient Air
¦LE DIYer Plaster Removal
¦LE DIYer Disturbance Attic Insulation
¦LE Potkolder
¦ CT Take-Home Garment Handler
¦LE DIYer Disturbance Ceiling Tiles
¦LE DIYer Disturbance Spackle
-Benchmark
¦LE DIYer Outdoor Disturbance Roof
¦LE DIYer Removal Ceiling Tiles
¦LE DIYer Indoor Disturbance Fillers
¦LE DIYer Outdoor Removal Roof
¦LE DIYer Removal Vinyl Floor Tiles
¦LE DIYer Indoor Removal Fillers
FigureApx M-6. Non-cancer Chronic Aggregate Risk across CT Scenarios for Take-Home, LE
DIYers, and LE General Population Risk to Occupational Activities Releases to Ambient Air
Figure Apx M-7 shows the combined CT non-cancer chronic risks for people living at a distance from
an occupational release activity (horizontal axis and boxes in figure), workers (dark blue bar), take-home
(orange bar), and DIYers (all other bars). This scenario build upon Figure Apx M-6 aggregation
scenario approach while adding workers. None of the aggregated activities resulted in over the
benchmark risks indicating that it likely requires HE tendencies to result in non-cancer chronic risks.
S 2.5E-03
W
O
2
„ 2.0E-03
o
o
=
"I 1.5E-03
£
| 1.0E-03
5
O
5.0E-04
Demolition
Firefighting Career
S* ¦$> (J> ^ ^ ^ ^
Firefighting Volunteer
llllllll
v* -P to® ^
General population distance from release activity (m)
¦CT High-Exposure Worker
¦CT DIYer Outdoor Removal Roof
¦ CT DIYer Indoor Disturbance Fillers
¦CT General Population Ambient Air
¦CT DIYer Disturbance Ceiling Tiles
¦ CT DIYer Indoor Removal Fillers
¦CT Take-Home Garment Handler
¦CT DIYer Removal Ceiling Tiles
—Benchmark
¦CT DIYer Outdoor Disturbance Roof
¦CT DIYer Removal Vinyl Floor Tiles
Figure Apx M-7. Central Tendency Non-cancer Chronic Aggregate Risk across Scenarios for
Workers, Take-Home, DIYers, and General Population Risk to Occupational Activities Releases
to Ambient Air
Non-cancer, Chronic Risk Aggregate Analysis across COUs
Figure Apx M-8 shows the non-cancer chronic risk aggregate results for general population, higher-
exposure workers, and take-home exposures LE, CT and HE tendencies. There are a total of six OESs
that can be aggregated and each of the scenarios (bars in figure) has a number in parenthesis
representing the number of OESs in the aggregation that were not individually above the risk
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benchmark. People living 10 m distance aggregate scenario was done with five of the six OESs, only
missing the waste handling COU/OES because it was above the risk benchmark. The CT worker
aggregate scenario was done with three of the six OES missing waste handling, removal/repair of
machinery, and handling of articles or formulations which were all above the risk benchmark on their
own. The aggregation of worker COUs is above the general population benchmark, 1 x 10~6 f/cc, but not
the occupational benchmark, 1 x 10~4 f/cc (not shown in the figure because it would be off the scale). All
activities at the HE tendency at the closest distance from occupational releases would be needed to drive
the MOE values over the benchmark as shown by the HE tendency box (third box first bar).
Eft
W
o
o
a
cz
u
a
o
£
7.0E-03
6.0E-03
5.0E-03
.g 4.0E-03
a
o
S-H
U 3.0E-03
2.0E-03
1.0E-03
0.0E+00
I
I
Low-End Tendency
General Population MOE
h„
Central Tendency General
Population MOE
High-End Tendency
General Population MOE
^ ^ ^ ^ ^ ^ ^ ^ ^
^ ^ Q? ^ N S ^ v ^ ^
JZj <0
V?"
&
¦Demolition, Renovation, Maintenance
¦Firefighting / Disaster Volunteer
^Handling articles or formulations
—Benchmark
N^'
General population distance from release activity (m)
iFirefighting / Disaster Career
Removal / Repair Machinery
i Waste Handling
FigureApx M-8. Non-cancer, Chronic Risk Aggregation across COUs for General Population,
Take-Home Exposures, and High-Exposure Workers
Parenthesis in the horizontal axis are the number of COUs in the specific aggregation scenario. There are a total of
six COUs if not included in the aggregation the COU exceeded the benchmark before aggregation.
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9999
10000
10001
10002
10003
10004
10005
10006
10007
10008
10009
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Appendix N DRAFT OCCUPATIONAL EXPOSURE VALUE
DERIVATION AND ANALYTICAL METHODS USED
TO DETECT ASBESTOS
EPA has calculated a draft 8-hour existing chemical occupational exposure value to summarize the
occupational exposure scenario and sensitive health endpoints into a single value. This calculated draft
value may be used in support of risk management efforts on asbestos under TSCA section 6(a), 15
U.S.C. 2605. EPA calculated the draft value to be 0.004 fibers/cc for inhalation exposures to asbestos as
an 8-hour time-weighted average (TWA) and for use in workplace settings (see Appendix N. 1) based on
the lifetime cancer inhalation unit risk (IUR) for lung cancer, mesothelioma, and other cancers.
TSCA requires risk evaluations to be conducted without consideration of cost and other non-risk factors,
and thus this draft occupational exposure value represents a risk-only number. If additional risk
management for asbestos follows the final Asbestos Part 2 risk evaluation, EPA may consider cost and
other non-risk factors, such as technological feasibility, the availability of alternatives, and the potential
for critical or essential uses. Any existing chemical exposure limit (ECEL) used for occupational safety
risk management purposes could differ from the draft occupational exposure value presented in this
appendix based on additional consideration of exposures and non-risk factors consistent with TSCA
section 6(c).
EPA expects that at the lifetime cancer occupational exposure value of 0.004 f/cc an employee also
would be protected against health effects resulting from chronic, non-cancer occupational exposures. In
addition, this value would protect against excess risk of cancer above the 1 x 10 4 benchmark value
resulting from lifetime exposure if ambient exposures are kept below this value.
Of the identified occupational monitoring data for asbestos, there have been measured workplace air
concentrations below the calculated occupational exposure value. A summary table of available
monitoring methods from the Occupational Safety and Health Administration (OSHA), the National
Institute for Occupational Safety and Health (NIOSH), and EPA are included below in Appendix N.2.
The table covers validated methods from governmental agencies and is not intended to be a
comprehensive list of available air monitoring methods for asbestos. The occupational exposure value is
above the limit of detection (LOD) and limit of quantification (LOQ) using at least one of the
monitoring methods identified.
For context, the Occupational Safety and Health Administration (OSHA) set a permissible exposure
limit (PEL) as an 8-hour TWA for asbestos of 0.1 f/cc (https://www.osha.gov/laws-
regs/regulations/standardnumber/1910/1910.1000TABLEZ2). However, as noted on OSHA's website,
"OSHA recognizes that many of its permissible exposure limits (PELs) are outdated and inadequate for
ensuring protection of worker health. Most of OSHA's PELs were issued shortly after adoption of the
Occupational Safety and Health Act in 1970 and have not been updated since that time." EPA's
calculated occupational exposure value is a lower value and is based on newer information and analysis
from this risk evaluation. In addition, OSHA's PEL must undergo both risk assessment and feasibility
assessment analyses before selecting a level that will substantially reduce risk under the Occupational
Safety and Health Act.
N.l Draft Occupational Exposure Value Calculations
This section presents the calculations used to estimate the draft occupational exposure value using inputs
derived in this draft risk evaluation.
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Draft Lifetime Cancer Occupational Exposure Value
The EVcancer is the concentration at which the extra cancer risk is equivalent to the benchmark cancer
risk of 1 x 10~4 per Equation_Apx N-l,
EquationApx N-l.
Benchmark Cancer ATlUR
£ 'rnnrtfr .. . „ *
cancer IUR(16,40) ED*EF*Vworker
„ . h 365d
1X10-4 24 d*^T~
= 0.004 fiber/cc
fiber * nh 250d ^ r
0.08 per cc 8^*—^—*1.5
Where:
ATiur
E V cancer
ED
EF
IUR(16.40)
V worker
Averaging time for the cancer IUR, based on study conditions and any
adjustments (24 hr/day for 365 days/yr) (Supplemental File: Releases and
Occupational Exposure Assessment; see Appendix C).
= Exposure limit based on excess cancer risk (1 x 10~4)
Exposure duration (8 hr/day) (see Section E.5.4)
Exposure frequency (250 days/yr), (see Section E.5.4)
Partial lifetime inhalation unit risk (0.08 per fiber/cc) for 40-year
exposure starting at age 16 (see Appendix K)
Volumetric adjustment factor for workers (1.5) (see Appendix E.5.4)
N.2 Summary of Air Sampling Analytical Methods Identified
EPA conducted a search to identify relevant NIOSH, OSHA, and EPA analytical methods used to
monitor for the presence of asbestos in air (see Table Apx N-l). This table covers validated methods
from governmental agencies and is not intended to be a comprehensive list of available air monitoring
methods for asbestos. The sources used for the search included the following:
1. NIOSH Manual of Analytical Methods (NMAM); 5th Edition
2. NIOSH NMAM 4th Edition
3. OSHA Index of Sampling and Analytical Methods
4. EPA Environmental Test Method and Monitoring Information
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TableApx N-l. Limit of Detection (LOD) and Limit of Quantification (LOQ) Summary for Air
Air Sampling
Analytical Method
Year
Published
LOD
LOQ
Notes
Source
NIOSH Method
7400: ASBESTOS
and OTHER
FIBERS by PCM
2019
0.00675
fibers/cc
0.10
fibers/cc
Appendix E of method
includes a table that
calculates an LOD and LOQ
assuming a 400 L air sample
[NIOSH Manual of
Analytical Methods
(NMAM 7400)1
NIOSH Method
7402:
Asbestos by TEM
2022
One confirmed
asbestos fiber
above 95% of
expected mean
blank value
N/A
The LOD depends upon
sample volume and quantity
of interfering dust and is
<0.01 fiber/cc for
atmospheres free of
interferences; method is
used in conjunction with
NIOSH Method 7400
[NIOSH Manual of
Analytical Methods
(NMAM 7402)1
OSHA ID-160:
Asbestos in Air
1997
0.001 fibers/cc
Not
reported
LOD assumes a sample
volume of 2,400 L
[OSHA Salt Lake
Technical Center
OSHA ID-1601
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