x°,EPA
United States Office of Chemical Safety and
Environmental Protection Agency Pollution Prevention
Summary of External Peer Review and Public Comments for Asbestos and
Disposition for Asbestos Part 1: Chrysotile Asbestos
Response to Support Risk Evaluation for
Asbestos
Part I: Chrysotile Asbestos
December 2020
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Table of Contents
Table of Contents 2
Abbreviations 10
List of Comments 14
1. Environmental Exposure and Release 19
1.1 Water (including wastewater and drinking water) 19
1.2 Biosolids 21
1.3 Asbestos containing building materials (ACBM) and waste 22
1.4 Waste disposal sites 23
1.5 Reuse of taconite tailings are sources of asbestos 24
1.6 Taconite mining is not a source of asbestos 24
1.7 Talc used in industrial and consumer products 25
1.8 TSCA applies to asbestos contaminants in TSCA-regulated consumer and industrial
applications of talc 26
1.9 Fabric/textiles are sources of asbestos 27
1.10 Cement 28
1.11 Treat woven and cement products 28
1.12 Vermiculite 29
1.13 Only chrysotile asbestos is being imported, processed, and distributed 30
1.14 More importation data are needed 30
1.15 Exposure does not occur during importation 33
1.16 Exposure can occur during importation 33
1.17 Other sources or releases 33
1.18 Include ingestion route of exposure 34
1.19 Acknowledge dermal exposure 35
1.20 Other environmental pathways of exposure 36
1.21 Potential for co-existing fibrous amphiboles and impurities 38
1.22 Other comments on environmental exposure and release 39
2. Occupational Exposure 40
2.1 EPA's general approach was valid 42
2.2 Support for TSCA definition of asbestos in Draft RE for Asbestos 42
2.3 Include legacy and other forms of asbestos in current risk assessment; excluding them
underestimates risk 42
2.4 Future supplemental evaluation for legacy asbestos 43
2.5 Need to address aggregate risk of exposures to COUs and legacy asbestos 44
2.6 Concerns about reduced involvement/enforcement of worker-related asbestos
regulations 46
2.7 Need IUR(s) to address all types of asbestos 46
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2.8 Legal requirement to address legacy uses 47
2.9 Methods to estimate past occupational exposures 48
2.10 Focus on modern fiber measurements appropriate 49
2.11 EPA should use its authority under TSCA to acquire sufficient information to
evaluate exposure 49
2.12 Characterize the market share of asbestos containing products 51
2.13 Low occupational exposures (multiple COUs) 52
2.14 Calculation of full-shift (8-hour) exposures using short-term, peak occupational
exposures 55
2.15 Reduction factors used for indoor bystander exposure are reasonable but inconsistent
57
2.16 Reliance on industry-reported practices could result in bias 59
2.17 General comments on COUs (COUs) for occupational exposure 60
2.18 Limited submissions by industry/publicly available information for COUs 61
2.19 EPA should use its TSCA information collection authorities 63
2.20 Chlor-alkali occupational worker exposure estimates 65
2.21 Chlor-alkali occupational non-user (ONU) exposure estimates 68
2.22 Concerns about properties of fibers in air 70
2.23 Age at first exposure and exposure duration 71
2.24 Approach for considering non-detect values 72
2.25 Sheet gasket stamping worker exposure estimates 74
2.26 Sheet gasket stamping and use ONU exposure estimates 76
2.27 Limited scope of industries relevant to sheet gasket stamping 78
2.28 Availability of quantitative data, study quality, or external validity for sheet gasket
stamping 79
2.29 Assumption that for any specific COU, the ONU exposures were the same for all
ONU types 81
2.30 Oilfield brake blocks worker exposure estimates 82
2.31 Oilfield brake blocks ONU exposure estimates 84
2.32 Study quality (e.g, use of monitoring data from oil rig drilling floors) 85
2.33 Aftermarket automotive brakes worker exposure estimates 85
2.34 Aftermarket automotive brakes ONU exposure estimates 88
2.35 Worker exposures for brake installation on export vehicles unlikely to match
aftermarket brake installation ONU 90
2.36 Workers engaged in clutch repair have lower exposures than brake mechanics 91
2.37 Other gaskets/utility vehicles (UTVs) worker exposure estimates 92
2.38 Consideration of additional studies on gasket use identified by SACC 93
2.39 Other gaskets/utility vehicles (UTVs) ONU exposure estimates 94
2.40 Requirement or assumption of use of personal protective equipment (PPE) 95
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2.41 Acute exposure events such as spills and accidents 99
2.42 Generalization of occupational exposure based on similar job title and working
condition 103
2.43 Suggestions for alternative information 103
2.44 Requirements for maximum number of "worst case" input parameters for a given use
104
2.45 Revisit assumptions and data for realism of high-end exposures 105
2.46 Select one method and apply it uniformly to calculate reduced exposure levels for
bystanders and ONUs 107
2.47 Seek input/increase transparency regarding coordination with OSHA and NIOSH 108
2.48 OSHA regulations 109
2.49 Other occupational exposure comments 110
3. Consumer Exposure 110
3.1 Aftermarket automotive brakes/linings and UTV gaskets consumer DIY and
bystander exposure estimates approach: General support Ill
3.2 EPA analysis not necessary 112
3.3 EPA does not incorporate the products and processes involved in vehicle repair.... 113
3.4 EPA does not consider aggregate/cumulative exposures 113
3.5 Prioritization of real-world data and use of unpublished data 115
3.6 EPA's selection of studies to support analysis of aftermarket brake consumer COUs
115
3.7 Data gaps regarding asbestos levels in U.S. or imported products 116
3.8 Data gaps regarding number of exposed consumers 118
3.9 DIY consumer exposure scenarios not appropriate or not considered 118
3.10 Consumer scenarios not considered by EPA 120
3.11 DIY consumer exposure levels overestimated 121
3.12 Exposure frequency/duration assumptions for DIY consumer exposure not supported
122
3.13 Task/activity assumptions for DIY consumer exposure not supported 123
3.14 DIY consumer exposure underestimated 124
3.15 Bystander exposure levels overestimated 125
3.16 Bystander reduction factors not appropriate or require clarification 126
3.17 Bystander exposure level underestimated 126
3.18 Sensitivity analysis/quantification of uncertainties 127
3.19 Text clarifications/other 128
3.20 Other 129
4. Human Health Hazard/Derivation of the Inhalation Unit Risk (IUR) 129
4.1 Focus on only lung cancer and mesothelioma is too limited 130
4.2 Consider the noncancer health endpoints 131
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4.3 Clarify how plural and/or peritoneal mesothelioma were considered 131
4.4 Concerns about the use of mortality rather than incidences 132
4.5 Concerns about combining lung cancer and mesothelioma for the CPF and IUR ... 133
4.6 Doses potentially causing mesothelioma are in the vicinity of doses that cause
asbestosis 135
4.7 Discuss wider context compared to other IRIS IURs 135
4.8 Justify why a separate IUR for chrysotile asbestos is needed 136
4.9 Textile industry does not represent the exposures of interest 137
4.10 Address heterogeneity between North Carolina and South Carolina textile worker
cohorts 140
4.11 Limitation of basing IUR on only two studies 145
4.12 Phase contrast microscopy (PCM) vs. transmission electron microscopy (TEM) for
fiber counts impact the IUR 146
4.13 Additional epidemiologic evidence is available for persons working with and around
aftermarket automotive brakes/linings (AABL) 149
4.14 Consider data from epidemiology studies and meta-analyses pertaining to exposures
to asbestos-containing brakes 153
4.15 Consider available inhalation toxicology studies concerning brake dust 157
4.16 Revisit exclusion of Quebec, Canada chrysotile miner study (Liddell studies) 158
4.17 Consider chrysotile miners studies from Balangero, Italy 161
4.18 Consider California Coalinga chrysotile miners and millers 162
4.19 Consider studies of South African chrysotile miners 163
4.20 Considered studies of Polish asbestos product manufacturing workers 163
4.21 Chongqing China cohort 164
4.22 Concerns with binning approach/estimating fiber size specific cancer potency factors.
164
4.23 Relative potency of different types of asbestos 165
4.24 Clarify derivation of mesothelioma potency factor 167
4.25 Cancer potency factor range 168
4.26 Short chrysotile fibers might pose no risk of cancer 169
4.27 Evidence of no safe exposure levels 170
4.28 Recalculate the potency factors considering Berman and Crump (2008) who used
individual [exposure] data 172
4.29 Justify choice of or replace AIC model-selection criterion 173
4.30 Fit and compare linear and exponential model 175
4.31 Consideration of background mesothelioma rates and basis of IUR concept of excess
risk 181
4.32 Risks are underestimated due to lack of an unexposed group for internal analyses. 186
4.33 Use a more appropriate "midpoint" for the highest exposed category 186
4.34 Method for correcting for underascertainment of mesothelioma 187
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4.35 Male and female lifetables are different 190
4.36 Consider effect modification by age 190
4.37 Considering detailed temporal aspects of exposure for lung cancer exposure-response
model 191
4.38 Clarify how lag period is incorporated 192
4.39 Latency of mesothelioma 193
4.40 Smoking as a confounding variable 193
4.41 Level of asbestos mortality in population 196
4.42 Consider conducting meta-analyses 199
4.43 Include confidence statements for IUR values 201
4.44 Adjust IUR based on potential bias for each individual uncertainty 203
4.45 Other suggested changes to calculations or content 204
4.46 IUR - general comments 206
4.47 Clearer documentation of IUR is needed 206
5. Human Health Risk Characterization 207
5.1 Provide more information on assumptions 207
5.2 Analysis supports conclusions 208
5.3 Draft RE for Asbestos overestimates cancer risk 209
5.4 Use of inhalation volumetric adjustment factor 212
5.5 EPA's approach for risk calculation 213
5.6 Clarity and validity of specific confidence summaries presented in Draft RE for
Asbestos Section 4.3 213
5.7 In-depth sensitivity analyses is a strength 214
5.8 Uncertainties, limitations, and strength of the unreasonable risk conclusions (Draft
RE for Asbestos Section 4.3) 215
5.9 Significant digits 217
5.10 Concerns about risk estimate benchmark for workers 217
5.11 An asbestos ban is not needed under TSCA 218
5.12 Asbestos should be banned under TSCA 219
5.13 Previous TSCA legislation 221
5.14 Include a "mobile app" for users to calculate risk 222
6. Environmental Risk Characterization and Determination 223
6.1 Overarching comments on environmental risk characterization 223
6.2 Risk to aquatic species not adequately evaluated 223
6.3 Limitations of EPA's conclusions 224
6.4 Alternative approaches for surface water scenarios 225
6.5 Discuss uncertainties about concentrations of asbestos in effluent 226
6.6 Action is needed to require measurement of asbestos in effluent 227
6.7 Environmental risk determination 228
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7. Potentially Exposed or Susceptible Subpopulations 229
7.1 Differentiate risk estimates for smokers and nonsmokers 229
7.2 Address population with underlying health conditions 230
7.3 Consider aggregate exposures and multiple pathways when defining PESS 231
7.4 Consider firefighters, teachers, contractors not covered by OSHA 232
7.5 Consider tribal communities 233
7.6 Family members and others in communities exposed through occupational take-home
exposures 233
7.7 Consider workers with unique conditions 234
7.8 Additional populations to consider 234
7.9 Subpopulations not defined appropriately 235
7.10 Extent to which the uncertainty around PESS been adequately characterized 235
7.11 Risk to DIYs and ONUs who would not be expected to use PPE (Draft RE for
Asbestos Sections 4.2.1 and 4.3.7) 236
8. Overall Content and Organization 237
8.1 Draft RE for Asbestos is clear, thorough, and transparent 238
8.2 Draft RE for Asbestos title is misleading 238
8.3 Clarify regulatory charge, scope, and rationale of evaluation 239
8.4 Expand discussion of mode of action (MO A) 240
8.5 Supplemental documents should include updated photos of asbestos-containing
building materials 241
8.6 Include CAS registry numbers 241
8.7 Tables should be condensed and modified for readability 241
8.8 Clarify derivation of IURllt 242
8.9 Other recommendations to improve document clarity, particularly regarding
uncertainties 242
8.10 Map and correlate asbestos deposits in natural environment 243
8.11 Define terms 243
8.12 Correct the attribution for statements about asbestos being vital 244
8.13 C orrect quotati on/citati on 244
8.14 Clarification on Jiang et al. (2008) - obtaining clutches or brakes with asbestos is not
likely in 2020 244
8.15 Revise how Paustenbach et al. (2006) is interpreted 245
8.16 Remove the term "inert" 245
8.17 Use the term "chrysotile asbestos" in place of the single word "chrysotile" 245
8.18 Clarify terms for asbestiform and non-asbestiform varieties 246
8.19 Use more complete descriptions of "risk" wording 246
8.20 Include data gaps section 247
8.21 Be clearer on how cited epidemiology papers conducted and modeled their studies247
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8.22 Rename the section "selected optical properties" 248
8.23 Redefine the term "most susceptible" 248
8.24 EPA ignored gaps identified in the Problem Formulation 248
8.25 The Draft RE for Asbestos is not "fit for purpose" 249
8.26 The Draft RE for Asbestos does not address TSCA requirements 250
8.27 Correct error in Table 2-4 250
8.28 Non-cancer effects of chrysotile are not similar to Libby amphibole 251
9. Systematic Review 251
9.1 Systematic review supplemental file effort recognized 251
9.2 Relevant literature sources were overlooked or deemed inadequate 252
9.3 Request to improve transparency, including use of previous assessments and process
for backward searching 252
9.4 Comments about criteria for data/study inclusion and exclusion 253
9.5 EPA should not rely on voluntary information from manufacturers/importers 255
10. Physical/Chemical Properties 255
10.1 Conduct studies on physical/chemical properties 255
10.2 Concerns about terminology and misclassification 256
10.3 Improve discussion of fiber length and aerodynamic aspects 257
10.4 Include information from animal studies on the physical-chemical properties 257
10.5 FDA's parallel effort on chrysotile 258
10.6 NIOSH has background information 258
11. Public Comment and Peer Review Processes 258
11.1 Concerns about insufficient time 258
11.2 Balance, independence, and bias of peer review 259
11.3 Withdraw draft and issue a revised Draft RE for Asbestos 261
12. Other 261
12.1 Agency should recognize impact of risk evaluation on tort/personal injury litigation...
261
12.2 EPA should expand the category for required notification to "any use" of asbestos 262
12.3 Concern about feasibility for timely review of risk evaluation or SNUR application....
262
12.4 State interest in ensuring Draft RE for Asbestos is conducted in accordance with
TSCA 263
12.5 Not prudent to burden the chlor-alkali industry while responding to COVID 263
12.6 EPA's narrow scope of evaluation for asbestos should not be a template for future
risk evaluation 263
12.7 EPA should continue to support asbestos regulations 264
12.8 Insurance coverage for medical surveillance for asbestos-exposed people 264
12.9 Consider Canada's regulatory approach for asbestos 265
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12.10 Availability of information on consumer products and associated manufacturers... 265
12.11 Research for worker conditions in asbestos mines outside of U.S 265
Cited References 266
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This document summarizes the external peer review and public comments that the EPA's Office of
Pollution Prevention and Toxics (OPPT) received for the draft risk evaluation of asbestos. It also provides
EPA's response to the comments received from the peer review panel and the public.
EPA appreciates the valuable input provided by the peer review panel and the public. The input resulted
in numerous revisions to Part 1 of the Risk Evaluation for Asbestos.
Peer review charge questions1 and the sections of the draft evaluation are used to categorize the peer
review and public comments into specific, issue-related main themes.
1. Environmental Exposure and Release
2. Occupational Exposure
3. Consumer Exposure
4. Human Health Hazard/Derivation of the Inhalation Unit Risk (IUR)
5. Human Health Risk Characterization and Determination
6. Environmental Risk Characterization and Determination
7. Potentially Exposed or Susceptible Subpopulations
8. Overall Content and Organization
9. Systematic Review
10. Physical/Chemical Properties
11. Public Comment and Peer Review Processes
12. Other
Peer review comments on the charge questions are typically presented first, organized by charge question
or risk evaluation topic in the following sections. These are followed by the public comments.
Abbreviations
AABL
Aftermarket automotive brakes/linings
AC
Asbestos-containing
ACBM
Asbestos-containing building materials
ACC
American Chemistry Council
ACE
Agency tariff code
ACM
Asbestos-containing material
AHERA
Asbestos Hazard Emergency Response Act
AIAN
American Indians/Alaska Natives
AIC
Akaike Information Criteria
APF
Assigned protection factors
ASHARA
Asbestos School Hazard Abatement Reauthorization Act
ATSDR
Agency for Toxic Substances and Disease Registry
BCF
Bioconcentration factor
BLS
U.S. Bureau of Labor Statistics
BRCA
BReast CAncer gene
CAA
Clean Air Act
1 These are the questions that EPA submitted to the panel to guide the peer review process.
Page 10 of 284
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CASRN
Chemical Abstracts Service Registry Number (referred to as CAS as well)
CBP
U.S. Customs and Border Protection
CDC
Centers for Disease Control
CDR
Chemical data reporting
COC
Concentrations of concern
COD
Chemical oxygen demand
COPD
Chronic obstructive pulmonary disease
COU
Condition of use
CPF
Cancer potency factor
CQ
Charge Question (to SACC)
CT
Central tendency
CWA
Clean Water Act
DIY
Do it yourself
DQE
Data quality evaluation
EBRI
Employee Benefit Research Institute
EC
Exposure concentration
ELCR
Excess lifetime cancer risk
EMP
Elongate mineral particles
EPA
U.S. Environmental Protection Agency
HEI
Health and Safety Executive in the United Kingdom
HERO
Health and Environmental Research Online
HTS
Harmonized tariff schedule
IARC
International Agency for Research on Cancer
ICD
International Classification of Disease
ILO
International Labor Organization
IRIS
Integrated Risk Information System
IUR
Inhalation unit risk
IURLLT
Less than a lifetime inhalation unit risk
KL
Lung cancer potency factor
KM
Mesothelioma potency factor
LOD
Limit of detection
LMS
Linear multistage (cancer risk model)
LNT
Linear no-threshold (cancer risk model)
MCL
Maximum contaminant level
MLE
Maximum likelihood estimation
MOA
Mode of action (toxicological)
MSDS
Material Safety Data Sheet
NC
North Carolina
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ND Non-detect
NESHAP National Emission Standards for Hazardous Air Pollutants
NIOSH National Institute for Occupational Safety and Health
NOAEL No-observed-adverse-effect level
NOEL No-observed-effect level
NPDES National Pollutant Discharge Elimination System
NY New York
OCSPP Office of Chemical Safety and Pollution Prevention
ONU Occupational non-user
OPPT Office of Pollution Prevention and Toxics
OSH Occupational Safety and Health (Act)
OSHA Occupational Safety and Health Administration
OSWER Office of Solid Waste and Emergency Response (renamed Office of Land and Emergency
Management)
PAH Polycyclic aromatic hydrocarbon
PBZ Personal breathing zone
PCB Polychlorinated biphenyl
PCM Phase-contrast microscopy
PEL Permissible exposure limit
PESS Potentially exposed or susceptible subpopulation
PHS U.S. Public Health Service
PMN Premanufacturing notice
POD Point of departure
POTW Publicly owned treatment works
PPE Personal protective equipment
RACM Regulated asbestos containing materials
RCRA Resource Conservation and Recovery Act
RE Risk evaluation
REA Risk evaluation for asbestos
RF Reduction factor
RfC Reference concentration
RfD Reference dose
RR Relative risk
SAB Science Advisory Board
SACC Science Advisory Committee on Chemicals
SC South Carolina
SCR Silicon-controlled rectifier
SDS Safety data sheet(s)
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SDWA
Safe Drinking Water Act
SEER
Surveillance, Epidemiology, and End Results Program
SMR
Standardized mortality ratio
SNUR
Significant New Use Rule
SOP
Standard operating procedure
STEL
Short-term-exposure limit
TEM
Transmission electron microscopy
TRI
Toxics Release Inventory
TSCA
Toxic Substances Control Act
TSCE
Two-stage clonal expansion (model)
TSS
Total suspended solids
TWA
Time-weighted average
TWF
Time-weighting factor
UNARCO
Union Asbestos and Rubber Company
US
United States
USGS
U.S. Geological Survey
UTV
Utility vehicle
WTC
World Trade Center (NY)
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List of Comments
#
Docket File
Submitter
SACC
EPA-HO-OPPT-2019-05 01-0113
Science Advisory Committee on Chemicals (SACC)
15
EPA-HO-OPPT-2019-0501-0015
Richard Haffey, President and Training Director, Mystic Air Quality Consultants,
Inc.
16
EPA-HO-OPPT-2019-0501-0016
ToxStrategies, Inc. on behalf of American Chemistry Council (ACC)
17
EPA-HO-OPPT-2019-0501-0017
C. Maahs
25
EPA-HO-OPPT-2019-0501 -0025
Brent Kynoch, Managing Director, Environmental Information Association (EIA)
26
EPA-HO-OPPT-2019-0501 -0026
Anonymous public comment
27
EPA-HO-OPPT-2019-0501 -0027
Anonymous public comment
28
EPA-HO-OPPT-2019-0501 -0028
Mark G. Ellis, President, Industrial Minerals Association - North America (IMA-
NA)
29
EPA-HO-OPPT-2019-0501 -0029
S. E. Strauss
30
EPA-HO-OPPT-2019-0501 -003 0
Kevin Bogue, Platform Environmental, LLC
31
EPA-HO-OPPT-2019-0501 -0031
Michelle Roos, Environmental Protection Network (EPN)
32
EPA-HO-OPPT-2019-0501 -0032
Julie E. Goodman et al., Gradient
34
EPA-HO-OPPT-2019-0501 -0034
David H. Garabrant, Emeritus Professor of Epidemiology and Occupational
Medicine, The University of Michigan
35
EPA-HO-OPPT-2019-0501 -003 5
Judith Nordgren, Managing Director, Chlorine Chemistry Division, American
Chemistry Council (ACC)
38
EPA-HO-OPPT-2019-0501 -003 8
John W. Spencer, President, Environmental Profiles, Inc.
39
EPA-HO-OPPT-2019-0501 -003 9
G. Mezei, S. Moolgavkar and F. Mowat, Exponent, Inc.
40
EPA-HO-OPPT-2019-0501 -0040
P. R. Williams
41
EPA-HO-OPPT-2019-0501 -0041
V. L. Roggli and T. A. Sporn
42
EPA-HO-OPPT-2019-0501 -0042
Dennis J. Paustenbach, President and David Brew, Toxicologist, Paustenbach and
Associates
Page 14 of 284
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#
Docket File
Submitter
43
EPA-HO-OPPT-2019-0501 -0043
M. C. Sharp
44
EPA-HO-OPPT-2019-0501 -0044
R. A. Lemen (corrected version is comment 57, so this comment is not cited in
summary)
45
EPA-HO-OPPT-2019-0501 -0045
J. Brent Kynoch, Managing Director, Environmental Information Association (EIA)
46
EPA-HO-OPPT-2019-0501 -0046
A. L. Frank
47
EPA-HO-OPPT-2019-0501 -0047
L. C. Oliver
48
EPA-HO-OPPT-2019-0501 -0048
Jacqueline Moline, Chair, Occupational Medicine, Epidemiology and Prevention,
The Donald and Barbara Zucker School of Medicine at Hofstra/Northwell
49
EPA-HO-OPPT-2019-0501 -0049
B. Castleman
50
EPA-HO-OPPT-2019-0501-0050
Raja Flores, System Chairman, Department of Thoracic Surgery, Mount Sinai
Health System
51
EPA-HO-OPPT-2019-0501-0051
Linda Reinstein, President and Co-Founder and Robert Sussman, Counsel, Asbestos
Disease Awareness Association (ADAO)
53
EPA-HO-OPPT-2019-0501-0053
Rebecca L. Reindel, Safety and Health Director, American Federation of Labor and
Congress of Industrial Organizations (AFL-CIO)
55
EPA-HO-OPPT-2019-0501-0055
C. Blake and R. Harbison
56
EPA-HO-OPPT-2019-0501-0056
Michele Carbone, Cancer Center, University of Hawaii
57
EPA-HO-OPPT-2019-0501-0057
R. A. Lemen
58
EPA-HO-OPPT-2019-0501-0058
P. Gottesfeld
59
EPA-HO-OPPT-2019-0501-0059
Anonymous public comment
60
EPA-HO-OPPT-2019-0501 -0060
Christy A. Barlow, Kimberly A. Hoppe Parr, and Kim E. Anderson,
GZA GeoEnvironmental, Inc.
61
EPA-HO-OPPT-2019-0501 -0061
A. M. Langer
62
EPA-HO-OPPT-2019-0501 -0062
Bertram Price, Price Associates, Inc.
63
EPA-HO-OPPT-2019-0501 -0063
J. M. Dement
64
EPA-HO-OPPT-2019-0501 -0064
Bryan D. Hardin, Vice President - Principal Toxicologist, J. S. Held, LLC
65
EPA-HO-OPPT-2019-0501 -0065
Jessica Ryman-Rasmussen, Senior Scientific Advisor, American Petroleum Institute
(API)
Page 15 of 284
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#
Docket File
Submitter
66
EPA-HO-OPPT-2019-0501 -0066
Allan Feingold, Medical Director, Occupational & Environmental Medicine, South
Miami Hospital
67
EPA-HO-OPPT-2019-0501 -0067
Steve Mlynarek, President, Applied Science Associates, Inc.
68
EPA-HO-OPPT-2019-0501 -0068
B. W. Case
69
EPA-HO-OPPT-2019-0501 -0069
Thomas G. Laubenthal, Technical Chief & Training Supervisor, The Environmental
Institute
70
EPA-HO-OPPT-2019-0501 -0070
Judith Nordgren, Managing Director, Chlorine Chemistry Division (CCD),
American Chemistry Council (ACC)
71
EPA-HO-OPPT-2019-0501-0071
Kirk T. Hartley, LSP Group LLC
72
EPA-HO-OPPT-2019-0501 -0072
Robyn Brooks, Vice President, Health, Environment, Safety, and Security, The
Chlorine Institute (CI)
73
EPA-HO-OPPT-2019-0501 -0073
Georges C. Benjamin, Executive Director, American Public Health Association
(APHA)
74
EPA-HO-OPPT-2019-0501 -0074
Ellen S. Tenenbaum and Craig H. Zimmerman, Attorneys, McDermott Will and
Emery LLP
75
EPA-HO-OPPT-2019-0501-0075
Kelsey Johnson, President, Iron Mining Association of Minnesota (IMA)
76
EPA-HO-OPPT-2019-0501 -0076
Andrey A. Korchevskiy et al, Director, Research and Development, Chemistry and
Industrial Hygiene, Inc. (C&IH)
77
EPA-HO-OPPT-2019-0501-0077
Xavier Becerra, Attorney General of California, California Department of Justice et
al.
78
EPA-HO-OPPT-2019-0501-0078
J. Sahmel
79
EPA-HO-OPPT-2019-0501 -0079
Coreen Robbins, Principal Industrial Hygienist, J.S. Held LLC.
80
EPA-HO-OPPT-2019-0501-0080
Kevin T. Wyles, Dentons US LLP on behalf of Morse TEC LLC
81
EPA-HO-OPPT-2019-0501-0081
Harold A. Schaitberger, General President, International Association of Fire Fighters
(IAFF)
82
EPA-HO-OPPT-2019-0501 -0082
B. T. Mossman
83
EPA-HO-OPPT-2019-0501-0083
Michael P. Walls, Vice President, Regulatory and Technical Affairs, American
Chemistry Council (ACC)
84
EPA-HO-OPPT-2019-0501 -0084
U.S. Chamber of Commerce et al.
Page 16 of 284
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#
Docket File
Submitter
85
EPA-HO-OPPT-2019-0501-0085
Randy Rabinowitz, Executive Director, Occupational Safety and Health Law Project
and Jonathan Kalmuss-Katz, Staff Attorney, Earthjustice on behalf of American
Federation of Labor and Congress of Industrial Organizations (AFL-CIO) et al.
86
EPA-HO-OPPT-2019-0501-0086
Bob Sussman, Counsel, Safer Chemicals Healthy Families (SCHF) et al.
87
EPA-HO-OPPT-2019-0501-0087
Nicholas Chartres et al., Associate Director, Science and Policy, Program on
Reproductive Health and the Environment, Department of Obstetrics, Gynecology
and Reproductive Sciences, University of California, San Francisco
88
EPA-HO-OPPT-2019-0501-0088
Dianne C. Barton, Chair, National Tribal Toxics Council (NTTC)
89
EPA-HO-OPPT-2019-0501-0089
Linda Reinstein, Cofounder, Asbestos Disease Awareness Organization (ADAO)
90
EPA-HO-OPPT-2019-0501 -0090
Evan M. Beckett et al., Cardno ChemRisk
91
EPA-HO-OPPT-2019-0501 -0091
Richard P. Krock, Senior Vice President, Regulatory and Technical Affairs, Vinyl
Institute (VI)
92
EPA-HO-OPPT-2019-0501 -0092
Bruce Stern, President, American Association for Justice (AAJ)
95
EPA-HO-OPPT-2019-0501 -0095
Dennis Paustenbach, Paustenbach and Associates
96
EPA-HO-OPPT-2019-0501 -0096
Nicholas Chartres, Associate Director, Program on Reproductive Health and the
Environment, University of California, San Francisco
97
EPA-HO-OPPT-2019-0501 -0097
Bob Sussman, Sussman & Associates on behalf of Asbestos Disease Awareness
Organization (ADAO)
98
EPA-HO-OPPT-2019-0501 -0098
Steven P. Compton, MVA Scientific Consultants
99
EPA-HO-OPPT-2019-0501 -0099
Penelope Fenner-Crisp, Environmental Protection Networka€< (EPN)
100
EPA-HO-OPPT-2019-0501-0100
Greg Brorby, Senior Consultant, ToxStrategies on behalf of American Chemistry
Council (ACC)
101
EPA-HO-OPPT-2019-0501-0101
J. Brent Kynoch, Managing Director, Environmental Information Association (EIA)
102
EPA-HO-OPPT-2019-05 01 -0102
Gabor Mezei, Principal Scientist, Exponent, Inc.
103
EPA-HO-OPPT-2019-0501-0103
Suresh Moolgavkar, Principal Scientist, Exponent, Inc.
104
EPA-HO-OPPT-2019-05 01 -0104
Linda Reinstein, Cofounder, Asbestos Disease Awareness Organization (ADAO)
105
EPA-HO-OPPT-2019-0501-0105
Tony Tweedale, Rebutting Industry's Science with Knowledge (R.I.S.K.)
Consultancy
Page 17 of 284
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Docket File
Submitter
106
EPA-HO-OPPT-2019-0501-0106
David H. Garabrant, Emeritus Professor of Occupational Medicine and
Epidemiology, The University of Michigan, Ann Arbor, Michigan
108
EPA-HO-OPPT-2019-0501-0108
Robyn Brooks, Vice President, Health, Environment, Safety, and Security, The
Chlorine Institute (CI)
109
EPA-HO-OPPT-2019-0501-0109
Chacko Mathew, Environmental Engineering Technology, Director, United
Industries Unlimited LLC
110
EPA-HO-OPPT-2019-05 01-0110
Robert M. Sussman, Counsel on behalf of Asbestos Disease Awareness
Organization (ADAO)
111
EPA-HO-OPPT-2019-05 01-0111
Comment submitted by Patrick Celestine, Federal Relations Counsel, American
Association for Justice (AAJ)
Page 18 of 284
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1. Environmental Exposure and Release
Charge Question 1
1.1 Please comment on whether the information presented supports the analysis and conclusion in the draft environmental exposure
section (Section 2.2 and Appendix D).
#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
1.1 Water (including wastewater and drinking water)
SACC,
47, 51
SACC COMMENTS:
• Recommendation 1: Provide a stronger statement of
uncertainty in the conclusion that environmental
receptors are not exposed to chrysotile asbestos in
waste or surface waters and reflect this in the DRE's
Executive Summary.
• Recommendation 2: If COU monitoring data are not
available, either make a statement that risk cannot be
evaluated, or use surface water measurements as a
"worst-case" scenario for comparison to
Concentrations of Concern (COC) values.
• Recommendation 3: Discuss other COU sources to
surface water including laundered clothing and surface
runoff following brake pad replacement or washing of
chrysotile-containing consumer products.
• Recommendation 4: Address exposures to
environmental receptors by terrestrial and drinking
water pathways.
• Recommendation 9: Given the uncertainties of
occurrence, measurement, and identification of
chrysotile fibers, TEM should be recommended for
future monitoring, especially in surface waters.
• Relatively high concentrations of asbestos have been
found in surface waters (ATSDR (2011) and mav be
derived from sources other than COUs.
EPA has revised the statement in the document suggesting
low risk. Based on the reasonably available literature and
information for chrysotile asbestos, the Executive Summary
adequately states there is low potential risk of exposure for
environmental risk to aquatic and sediment-dwelling
receptors, but uncertainty is acknowledged. EPA concluded
there is no unreasonable risk to aquatic or sediment-dwelling
environmental organisms using reasonably available literature
as described in Section 4.1. Use of surface water
measurements as a "worst-case" scenario for comparison to
COC values would not be relevant to Part 1 of the Risk
Evaluation because the surface water data are not specific to
chrysotile and are not related to COUs included in Part 1.
Because these other sources of asbestos in surface water are
not relevant, EPA did not expand this discussion on sources.
These surface water measurements may be considered in Part
2 of the risk evaluation to evaluate risk from other uses of
asbestos not included in Part 1, as appropriate. EPA is
confident that relevant COUs were identified and included in
Part 1 of the Risk Evaluation for chrysotile asbestos based on
reasonably available information, as described in the Problem
Formulation document that was made available for public
comment. Legacy uses and other fiber types of asbestos may
contribute to surface water contamination, but that will be
determined in Part 2 of the Risk Evaluation for Asbestos.
Terrestrial exposure and drinking water pathways were
excluded from Part 1 of the Risk Evaluation as stated in the
Page 19 of 284
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PUBLIC COMMENTS:
• Asbestos in drinking water can result from leaching of
naturally occurring asbestos from soil and rock erosion
and "loose fibers spreading into the environment from
nearby construction sites or landfills. Disposing of
older asbestos products in the environment can create
toxic runoff that eventually flows into watersheds."
• Exceedances of the MCL for asbestos in drinking water
(which was set by EPA in 1982) have been detected in
some of drinking water systems and are more likely in
areas contaminated by erosion from natural asbestos
deposits or from mining operations (EWG (2019;
Howe et al. (1989; Kanarek et al. (1981; Sigurdson et
al. (1981; Kanarek et al. (1980; Craun et al. (1977; U.S.
EPA (1976V
Section 4.1 and in the Executive Summary of Part 1; relevant
terrestrial pathways, including biosolids, and drinking water
pathways are covered under the jurisdiction of the SDWA,
CAA, and CWA. Regarding methods used for asbestos
measurements, EPA acknowledges the advantages of using
TEM, such as providing higher definition for the
identification and quantification of asbestos fibers when
compared to PCM techniques. In Section 4.3.5, EPA states:
"The analytical method used to measure exposures in the
epidemiology studies is important in understanding and
interpreting the results as they were used to develop the IUR"
As provided in more detail in Section 3, the IUR for "current
use" asbestos (i.e., chrysotile) is based solely on studies of
PCM measurement as TEM-based risk data are limited in the
literature and the available TEM results for chrysotile
asbestos lack modeling results for mesothelioma. Further, all
of the industrial hygiene sampling of chrysotile asbestos
associated with the COUs were measured using PCM.
With respect to potential water quality implications of
asbestos leaching from naturally occurring sources and
construction/demolition waste landfill disposal, currently
there are no active mining operations of naturally occurring
asbestos in the United States. In addition, naturally occurring
asbestos is not a COU to be addressed by the EPA in Part 1 of
the Risk Evaluation. As mentioned in the asbestos PF
document, releases associated with construction sites waste
disposal into construction/demolition waste landfills are
primarily regulated under authorized state regulatory
programs. States must also implement limited federal
regulatory requirements for siting, groundwater monitoring,
and corrective action, and a prohibition on open dumping and
disposal of bulk liquids. Therefore, EPA is not including the
construction/demolition waste landfill disposal pathway in
Part 1 of the Risk Evaluation. Releases associated with
landfill disposal are regulated under landfill special
requirements for handling and securing the asbestos-
Page 20 of 284
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#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
containing waste regulated under NESHAP to prevent
releases of asbestos into the air. This includes sealing
regulated asbestos-containing waste material in a leak-tight
container, reducing possible environmental releases to ground
water. While permitted and managed by the individual states,
municipal solid waste landfills are required by federal
regulations to implement some of the same requirements as
RCRA Subtitle C landfills, generally including leachate
collection with the use of a liner system and conducting
groundwater monitoring and corrective action when releases
are detected. These actions help reduce any potential landfill
leachate releases to groundwater. Finally, chrysotile asbestos
is a fiber and will likely be entrained in soil and is not likely
to be leached out of a landfill. Given these controls, general
population exposure to asbestos in groundwater from landfill
leachate is not expected to be a significant pathway. EPA has
not included these landfill pathways in Part 1 of the Risk
Evaluation.
EPA acknowledges the documented presence of asbestos
fibers in drinking water. However, compliance/non-
compliance with statutory requirements outside of TSCA is
not a component to consider when conducting Risk
Evaluations under TSCA. Compliance/non-compliance issues
are addressed under separate enforcement authorities for each
statute along with settlement of identified non-compliance
issues.
1,2 Biosolids
SACC
SACC COMMENTS:
• Biosolids are a source of asbestos exposure, as
relatively high concentrations of asbestos have been
found in biosolids (ATSDR (2011) and mav be derived
from sources other than COUs.
EPA believes the intended reference in this comment should
be the 2001 ATSDR Toxicological Profile for Asbestos,
which indicates that asbestos was present in 34 of 51 sludge
ash samples at levels ranging from 1-10%. EPA evaluated this
report and other reasonably available information as described
in Part 1 of the Risk Evaluation and in the Problem
Page 21 of 284
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#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
Formulation document. As stated in Section 2.5.3.2 of the
Problem Formulation document, EPA expects that
concentrations of chrysotile asbestos in biosolids due to
relevant COUs is low and that "re-suspension of the asbestos
fibers into air following biosolid land application, although
possible, will result in exceedingly low airborne
concentrations." EPA did not evaluate hazards or exposures
from chrysotile asbestos releases to terrestrial pathways,
including biosolids, for terrestrial organisms, which was
described in Section 2.5.3.3 of the Problem Formulation
document.
1.3 Asbestos containing building materials (ACBM) and waste
45, 46,
47, 50,
51,68,
69, 73,
77, 85,
89, 92,
104
PUBLIC COMMENTS:
• Asbestos can be released into the air during building
repair, modeling and demolition, due to the disturbance
of ACBM such as insulation, fireproofing material, dry
wall, and ceiling and floor tile and many other
materials, which results in asbestos exposure to
construction workers, nearby residents, pedestrians and
bystanders.
• EPA does not estimate the number of buildings that
contain asbestos. The most recent data from the US
Census Bureau's American Housing Survey indicates
that 40% of the nation's 118 million housing units (i.e.,
47.2 million) were built before 1970. EPA could also
use data from the AHS to estimate the annual number of
renovations, repairs, and remodeling in which ACM
may be encountered.
• Amphiboles from Libby and other asbestos remain in
buildings (e.g, attic insulation) where ongoing use and
eventual disposal create risks for residents and workers,
including firefighters.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), EPA will
evaluate legacy asbestos uses including asbestos-containing
building materials (ACBM) and associated disposals of those
materials in Part 2 of the risk evaluation. Legacy asbestos
uses are uses for which manufacture, import, processing and
distribution no longer occur but the uses are still known,
intended, or reasonably foreseen to occur. EPA will include
such uses and associated disposals in Part 2 of the Risk
Evaluation for Asbestos, beginning with a draft scope
document. EPA will use reasonably available information to
determine the number of buildings that continue to contain
asbestos.
Libby Amphibole asbestos, which is a mixture of several
mineral fibers such as tremolite, winchite, and richterite, was
found in vermiculite ore mined near Libby, MT and
extensively distributed throughout the United States during
the 20th century. Vermiculite from Libby, MT had a range of
commercial applications, the most common of which included
packing material, attic and wall insulation, spray-on fire
proofing, various garden and agricultural products, and
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#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
• Libby Amphibole is still present at the Libby mining
site and other inactive sites.
• With the projected increases in severe weather,
including droughts, hurricanes, and tornadoes, EPA
Draft RE for Asbestos should include an assessment of
the likelihood and magnitude of occupational and
community exposure from damaged residential and
commercial buildings.
• Single-family homes, small rental properties, schools,
factories, and non-federal public buildings were not
addressed.
• Demolition of buildings that contain legacy and other
asbestos-containing materials can expose construction
workers, nearby residents, pedestrians, and bystanders.
• Asbestos demolition projects were not addressed under
CAA because NESHAP does not apply to residential
buildings with 4 or fewer units, projects that involve
less than a regulated quantity of RACM, or planned
demolitions of any building or unplanned events when
buildings are destroyed by fire.
• The 'use' of the material does not end at the time of
manufacture or installation. For many of these
materials, the 'use' only begins at installation. Building
'users' are at risk of asbestos exposure from installed
legacy asbestos-containing materials, which can be
disturbed by vibration, air erosion, water damage, or
which citizens and tradesmen might contact directly
(Kvnoch (2018).
various cement and building products. The Libby, MT
vermiculite mine closed in 1990. EPA will address whether
asbestos associated with vermiculite originating from Libby,
MT will be included in Part 2 of the risk evaluation,
beginning with a draft scope document.
1.4 Waste disposal sites
51,77,
89
PUBLIC COMMENTS:
• Asbestos-contaminated waste is prevalent both at
inactive waste sites and active landfills and industrial
EPA is aware of asbestos-containing building materials
(ACBMs) releases to landfills. The EPA is not including
legacy asbestos uses, including ACBMs, in Part 1 of the Risk
Evaluation. The EPA will evaluate the legacy asbestos and
Page 23 of 284
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#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
facilities (ATSDR (2001), where asbestos has been
detected in air, groundwater, or surface water.
• TRI data demonstrates a relatively large increase in total
on-site and off-site disposal or other releases of friable
asbestos since 2009, with a vast majority released to
land. Poor waste management at landfills and
construction sites, as well as after disasters that disrupt
ACBMs, poses a significant danger to workers and the
public.
• The industry accounting for the highest release
quantities of friable asbestos is the hazardous waste
treatment and disposal sector, followed by the
petroleum and other chemical and electric sectors.
However, due to the limitations of TRI reporting
requirements, it is likely that the amount of asbestos-
containing waste managed or disposed of was
significantly higher than reported.
the associated disposals of those materials in Part 2 of the
Risk Evaluation.
1.5 Reuse of taconite tailings are sources of asbestos
26
PUBLIC COMMENTS:
• The taconite industry markets the use of taconite
tailings for road asphalt, and taconite tailings are being
used for road asphalt throughout Minnesota and
possibly in other states. Some asbestos is likely released
through road wear, but release of asbestos certainly is a
concern when the roads are dug up and repaired.
Therefore, mining of taconite tailings through the Iron
Range should be included in the draft RE.
The Agency will consider whether uses of taconite contain
fibers that fall within the definition of asbestos and whether
uses of taconite are a COU for asbestos to be included in Part
2 of the risk evaluation. Therefore, this document does not
include taconite tailings for road asphalt COU.
1.6 Taconite mining is not a source of asbestos
75
PUBLIC COMMENTS:
• EPA should state explicitly in the final risk evaluation
that non-asbestiform EMPs (cleavage fragments)
encountered during taconite mining do not fall within
Part 1 of the Risk Evaluation for Asbestos includes COUs for
chrysotile asbestos, and relevant exposure pathways were
described in the Scope document. Taconite mining was not
included in the Scope, Problem Formulation, or draft Risk
Evaluation as a source of exposure to chrysotile asbestos.
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#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
the TSCA definition of asbestos and are not covered by
the risk evaluation.
• Nearly all taconite iron ore produced in the United
States is supplied to the US domestic steel industry. It is
therefore of national and strategic importance and has
major impacts on local economies and jobs where these
mines are located.
• A survey of the Peter Mitchell Pit located in the Mesabi
Iron Range found that "no asbestos of any type was
found in the mine pit." Improved analytical techniques
have confirmed that taconite mining generates short
EMP fragments that are not asbestiform fibers (but
rather are non-asbestiform minerals), allowing EPA to
come to a definitive conclusion that taconite mining
operations do not generate asbestos. In the context of
the Clean Air Act asbestos NESHAP regulation (84
Fed. Reg. 50660, 50683 (Sept. 25, 2019); see 40 CFR
§61.141; which uses the same definition of asbestos as
TSCA), EPA cited the Peter Mitchell Pit study of
taconite ore mining and concluded that EMPs
encountered during taconite mining do not meet the
definition of 'asbestos' found in current EPA
regulations and technical documents.
• The commercial product produced in a taconite mining
operation is a fired iron ore pellet that has been exposed
to heat in a furnace in excess of 2,000°F, which would
eliminate any fibrous properties. As such, EPA should
exclude taconite mining from the scope of its current
and supplemental TSCA risk evaluations for asbestos.
EPA deemed it unnecessary to revise Part 1 of the Risk
Evaluation to explicitly note exclusion of taconite mining.
1.7 Talc used in industrial and consumer products
48, 50,
51,77,
86, 104
PUBLIC COMMENTS:
• Industrial uses of talc are diverse and include the
manufacturing of plastics, ceramics, paint, paper,
EPA is aware that talc originating from certain sources and
used in consumer and industrial applications may contain
asbestos. However, considering the significant scope of
evaluating the potential risks posed to individuals from
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#
Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
roofing material, lubricants, and insecticides/
fungicides.
• Talc-contaminated consumer products include baby
powder, makeup products, crayons and children's toys.
• The presence of a mixture of asbestos fiber types in talc
is well-documented (I ARC) (J eh an (1984; Rohl et al.
(1976a).
• The omission of talc-based consumer and industrial
applications from the draft evaluation is a significant
gap because of the likelihood that some grades of talc
used in these applications are contaminated by asbestos,
putting consumers and workers at risk. EPA should
include these COUs in its risk evaluation.
• While not every talc deposit contains asbestos, talc
deposits have been identified in mineral formations that
include, or are located near, asbestos deposits. Lung
illnesses (scarring, lung cancer, and mesothelioma) have
been discovered among NY talc miners in the mid-
1900s (Kleinfeld et al. (1967; Kleinfeld et al. (1955;
Porro et al. (1942). A recent effort bv Finkelstein (2012)
to uodate Honda et al. (2002) provides further evidence
that asbestos-containing talc causes mesothelioma
(Finkelstein (2012).
• The extent to which talc contains asbestos is not always
known, but typically industrial-grade talc undergoes less
extensive processing than talc used in personal care
products and is more likely to contain impurities.
• Industrial uses of talc likely expose thousands of
workers to talc powder by inhalation and dermal
contact.
• Exposure to asbestos in talc has been linked to ovarian
cancer and mesothelioma. This risk should be addressed
by EPA in the asbestos evaluation.
exposure to talc, it would be more appropriate to evaluate talc
(and any known or reasonably foreseen co-located asbestos
therein) in a separate and subsequent risk evaluation focused
on talc.
1.8 TSCA applies to asbestos contaminants in TSCA-regulated consumer and industrial applications of talc
Page 26 of 284
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Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
51
PUBLIC COMMENTS:
• EPA's assertion that contaminants in consumer and
industrial products are outside the scope of TSCA risk
evaluations because their presence is "inadvertent" is an
incorrect interpretation of the law. EPA's policy has
always been to treat contaminants found in materials as
manufactured for commercial purposes subject to
TSCA, regardless of whether the contaminant is
"intended" to be present. EPA's premanufacture notice
(PMN) regulations under section 5 require
manufacturers of "new chemicals" to notify EPA of
"impurities" found in these substances (40 CFR §
720.45(b). EPA has used its authorities under section 5
of TSCA to restrict these impurities where they may
present unreasonable risks to health or the environment.
• Asbestos that is mined "coincidentally" during the
mining of talc and lacks "separate commercial value" is
nonetheless "manufactured for commercial purposes"
under TSCA and is subject to TSCA authorities.
• Impurities that are not "intended" to be manufactured
but are "known or reasonably foreseen" to be produced
during the manufacture of another substance fall within
the definition of "COUs" in Section 3(4) of TSCA.
Therefore, inadvertent presence in commercially mined
talc is a COU of asbestos which must be addressed in
EPA's asbestos risk evaluation.
As stated in the Procedures for Chemical Risk Evaluation
Under the Amended Toxic Substances Control Act, 82 FR
33726, 33730 (July 20, 2017), EPA may choose not to include
a particular impurity within the Scope of any risk evaluation,
where EPA has a basis to foresee that the risk from the
presence of the impurity would be ' de minimis' or otherwise
insignificant. In other cases, it may be more appropriate to
evaluate potential risks arising from a chemical impurity
within the scope of the risk evaluation for the separate
chemical substances that bear the impurity.
EPA is aware that talc originating from certain sources and
used in consumer and industrial applications may contain
asbestos. However, considering the significant scope of
evaluating the potential risks posed to individuals from
exposure to talc, the Agency believes it would be more
appropriate to evaluate talc (and any known or reasonably
foreseen co4ocated asbestos therein) in a separate and
subsequent chemical risk evaluation of talc.
1,9 Fabric/textiles are sources of asbestos
46
PUBLIC COMMENTS:
• Asbestos blankets and gloves are still currently used for
welding activities, and regular repair work on turbine
linings containing asbestos continues to expose workers
to asbestos containing textiles.
Following the review of published literature and online
databases including the most recent data available from the
U.S. Geological Survey's (USGS) Mineral Commodities
Summary and Minerals Yearbook and government and
commercial trade databases, EPA believes asbestos blankets
and gloves are not manufactured in the United States or
imported into the country for use. Furthermore, on April 25,
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Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
2019, EPA finalized an Asbestos Significant New Use Rule
(SNUR) under TSCA Section 5 that prohibits manufacture
(including import) or processing of discontinued uses of
asbestos (such as asbestos blankets and gloves) from
restarting without EPA evaluating and making a
determination on whether the chemical presents unreasonable
risks to health and the environment and to take regulatory
action, as appropriate, under TSCA Section 5.
As part of developing the supplemental scope document for
legacy uses and other fiber types of asbestos (Part 2 of the
Risk Evaluation), EPA will address legacy uses, such as
asbestos blankets and gloves, that while no longer imported
into or manufactured in the United States, may be still in use
commercially or by consumers, and therefore, should be
included in the supplemental scope document.
1.10 Cement
46,51,
98
PUBLIC COMMENTS:
• There are exposures from asbestos-cement piping.
• Asbestos enters water supplies primarily from the
deterioration of asbestos-cement pipes, which make up
between 12 and 15% of drinking water systems in the
United States.
EPA determined, after researching and contacting potential
importers, that there is no evidence to support that asbestos
cement products or packings are COUs of asbestos that
continue to be manufactured (including imported), processed,
or distributed in the U.S. As part of developing the
supplemental scope document for Part 2 (legacy uses and
other fiber types of asbestos), EPA will investigate whether
asbestos cement products or packings should be included in
the supplemental scope document.
1.11 Treat woven and cement products
51
PUBLIC COMMENTS:
• EPA does not include cement and woven products in the
Draft RE for Asbestos because it "has not found any
evidence to suggest that woven products (other than
those that are already covered under a distinct COU
such as brake blocks used in draw works) or cement
EPA determined following further research and after
contacting potential importers that there is no evidence to
support that asbestos-containing woven products (other than
those that are already covered under a distinct COU such as
brake blocks used in oil drilling equipment), cement products,
or packings are COUs of asbestos that continue to be
Page 28 of 284
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products imported into the United States contain
asbestos." The International Trade Commission import
summaries, however, have consistently shown
substantial incoming shipments of asbestos fabric and
cement. EPA stated that it contacted potential foreign
exporters of asbestos woven and cement products, and
the companies stated that they do not have customers in
the US. However, EPA only spoke to two Mexican
companies, not all the other listed foreign exporters of
these products, and by phone rather than via written
statements.
• The inclusion of asbestos woven and cement products in
its Significant New Use Rule (SNUR) (40 CFR
§721.11095) is not an adequate substitute for addressing
them in the Draft RE for Asbestos. The SNUR makes
no finding of unreasonable risk for these or other
asbestos-containing products nor is it a prohibition on
their use; instead, it merely requires EPA to be notified
before their reintroduction into US commerce. By
contrast, the risk evaluation would determine
unreasonable risk for all asbestos COUs and lay the
foundation for a ban of products subject to that
determination. The commenter requested that EPA treat
asbestos woven and cement products as COUs under
TSCA and add them to the evaluation.
manufactured, imported or distributed in the United States.
Data that the commenter references from the International
Trade Commission regarding asbestos woven and cement
products is likely the result of misreporting (see Appendix C
of Part 1 of the Risk Evaluation). The Agency worked with
federal partners to better understand the asbestos-containing
product import information. In coordination with Customs
and Border Protection (CBP), EPA reviewed available import
information. CBP provided import data for asbestos HTS
codes in CBP's Automated Commercial Environment (ACE)
system, which provided information for 26 companies that
reported the import of asbestos-containing products between
2016 and 2018. EPA contacted these 26 companies in order to
verify the accuracy of the data reported in ACE. Of these 26
companies, 22 companies confirmed that the HTS codes were
incorrectly used and the imported articles did not contain
asbestos. One company could not be reached when contacted
by EPA and three companies confirmed that the asbestos HTS
codes entered in ACE were correct corresponding to the uses
of asbestos gaskets, brake linings and rubber asbestos sheets
used to make gaskets.
Furthermore, on April 25, 2019, EPA finalized an Asbestos
Significant New Use Rule (SNUR) under TSCA Section 5
that prohibits manufacture (including import) or processing of
discontinued uses of asbestos including asbestos woven
products (other than brake blocks used in oil drilling
equipment) and asbestos cement products from restarting
without EPA evaluating and making a determination on
whether the chemical presents an unreasonable risk to health
and the environment and to take regulatory action, as
appropriate, under TSCA Section 5. Since finalization of the
asbestos SNUR in 2019, EPA has not received any significant
new uses notices that would be required prior to import
asbestos woven products (other than brake blocks used in oil
drilling equipment), packings and asbestos cement products.
1,12 Vermiculite
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Summary of Comments for Specific Issues Related to
Charge Question 1
EPA/OPPT Response
51
PUBLIC COMMENTS:
• Vermiculite contaminated with amphibole has been
used as insulation in some 10-30 million homes and can
be released into indoor and outdoor air when there is
disruption caused by extreme weather or home
remodeling or demolition, exposing residents and
construction workers.
As part of developing the scope document for Part 2: legacy
uses and other fiber types of asbestos, EPA will consider
whether legacy uses of vermiculite orginating from Libby,
MT should be included. The scope document will be made
available for public comment.
1.13 Only chrysotile asbestos is being imported, processed, and distributed
28, 42,
61, 84
PUBLIC COMMENT:
• A commenter agreed that only chrysotile asbestos is
currently being imported in the raw form or imported in
products (Draft RE for Asbestos p. 132, In. 4864-4865).
It is used to create diaphragms for the chlor-alkali
industry.
• The Draft RE for Asbestos's conclusions that the only
form of asbestos known to be imported, processed, or
distributed for use in the US is chrysotile is justified.
• The fiber consumed in US commerce today (chrysotile)
is mostly imported in finished product form.
• None of the potent forms of asbestos are imported into
the US.
EPA appreciates the comment.
1.14 More importation data are needed
SACC,
42,51,
68, 80,
97
SACC COMMENTS:
• Recommendation 67: Actively collect more data on
imported products suspected of containing asbestos
instead of relying exclusively on voluntary reporting.
• The Draft RE for Asbestos states that it is "highly
certain" that import of ACM beyond the six product
categories does not occur. Given USGS data on imports,
the following HTS codes were not specifically
addressed in the DRE: 6812.99.0004 (yarn and thread);
6812.99.0004 (crocidolite products except footwear);
6812.91.9000 (clothing except footwear); 6812.99.0025
EPA conducted extensive research and outreach to determine
the COUs of chrysotile asbestos and activities that do not
qualify as COUs. This included EPA's review of published
literature and online databases including the most recent data
available from EPA's Chemical Data Reporting program
(CDR), EPA's Toxics Release Inventory (TRI) program,
Safety Data Sheets (SDSs), the United States Geological
Survey's Mineral Commodities Summary and Minerals
Yearbook, the U.S. International Trade Commission's
Dataweb and government and commercial trade databases.
EPA also reviewed company websites of potential
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(building materials). If these have been investigated,
then they should also be listed in Appendix C.
PUBLIC COMMENTS:
• The Draft RE for Asbestos repeatedly admits EPA has
virtually no information on imported asbestos-
containing products, including the quantities, the
number of end-users and the sites where asbestos
exposure occurs.
• According to the USGS, EPA allowed 280,325 metric
tons of asbestos to be imported from 1991 to 2018.
Based on 2019 [USGS] data, the total amount of raw
asbestos imported into the US from Brazil and Russia
was 750 metric tons in 2018 (UsgsJ2020); however,
only a modest amount of documentation supports this
claim.
• The U.S. Geological Survey for Asbestos 2020 states
that "a small, but unknown, quantity of asbestos was
imported within manufactured products, including brake
blocks for use in the oil industry, rubber sheets for
gaskets used to create a chemical containment seal in
the production of titanium dioxide, certain other types
of preformed gaskets, and some vehicle friction
products" (Usgs (2020). EPA is not aware of the
volume of those imports (Draft RE for Asbestos In.
1305-1307).
• EPA had the authority and the duty under TSCA to do
more to acquire information prior to publishing the
Draft RE for Asbestos. The power to compel
information from the entities profiting from the
manufacture/import of subject chemicals is central to
TSCA.
manufacturers, importers, distributors, retailers, or other users
of asbestos.
EPA also considered comments received on the Scope of the
Risk Evaluation for Asbestos, the Problem Formulation of the
Risk Evaluation and the draft Risk Evaluation for Asbestos.
In addition, EPA convened meetings with companies,
industry groups, chemical users, and other stakeholders to aid
in identifying COUs and verifying COUs identified by EPA.
Although there is some uncertainty regarding the amount and
number of exposed individuals for the asbestos COU, EPA
believes the remaining asbestos uses that are imported,
manufactured, processed and distributed are sheet gaskets,
brake blocks, aftermarket automotive brakes/linings, other
vehicle friction products, and other gaskets. These asbestos
uses align with what is listed as asbestos products that
continue to be imported into the U.S. according to the most
recent (2020) USGS Mineral Commodities Summary for
asbestos found at
https://www.usgs.gov/centers/nmic/asbestos-statistics-and-
information.
In regards to the referenced HTS codes pertaining to products
not evaluated in the DRE: 6812.99.0004 (yarn and thread);
6812.99.0004 (crocidolite products except footwear);
6812.91.9000 (clothing except footwear); 6812.99.0025
(building materials), EPA believes the listing of these
products is likely the result of misreporting (see Appendix C
of Part 1 of the Risk Evaluation).
The Agency worked with federal partners to better understand
the asbestos-containing product import information. In
coordination with Customs and Border Protection (CBP),
EPA reviewed available import information. CBP provided
import data for asbestos HTS codes in CBP's Automated
Commercial Environment (ACE) system, which provided
information for 26 companies that reported the import of
asbestos-containing products between 2016 and 2018. EPA
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contacted these 26 companies in order to verify the accuracy
of the data reported in ACE. Of these 26 companies, 22
companies confirmed that the HTS codes were incorrectly
used and the imported articles did not contain asbestos.
Furthermore, on April 25, 2019, EPA finalized an Asbestos
Significant New Use Rule (SNUR) under TSCA Section 5
that prohibits manufacture (including import) or processing of
discontinued uses of asbestos including asbestos woven
products (other than brake blocks used in oil drilling
equipment) and asbestos cement products from restarting
without EPA evaluating and making a determination on
whether the chemical presents an unreasonable risk to health
and the environment and to take regulatory action, as
appropriate, under Section 5.. Since finalization of the
asbestos SNUR in 2019, EPA has not received any significant
new uses notices that would be required prior to import
asbestos woven products (other than brake blocks used in oil
drilling equipment) and asbestos cement products.
As such, EPA had sufficient information to complete the Part
1 of the Risk Evaluation (Chrysotile Asbestos) using a weight
of scientific evidence approach. EPA selected the first 10
chemicals for risk evaluation based in part on its assessment
that these chemicals could be assessed without the need for
regulatory information collection or development. When
preparing this risk evaluation, EPA obtained and considered
reasonably available information, defined as information that
EPA possesses, or can reasonably obtain and synthesize for
use in risk evaluations, considering the deadlines for
completing the evaluation. However, EPA will continue to
improve on its method and data collection for the next round
of chemicals to be assessed under TSCA.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA 943 F.3d 397. (9th Cir. 2019), the Agency
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will evaluate legacy asbestos uses and associated disposals of
those uses. EPA will include such uses and associated
disposals in Part 2 of the Risk Evaluation for Asbestos,
beginning with a draft scope document for Part 2 of the Risk
Evaluation for Asbestos.
1.15 Ex
josure does not occur during importation
72
PUBLIC COMMENTS:
• The Chlorine Institute agrees with the Draft Risk
Evaluation for Asbestos that asbestos exposures are not
expected during the import process (In. 7665-7671) or
when handling fabricated diaphragms (Draft RE for
Asbestos In. 2121) because the asbestos is tightly
controlled.
EPA agrees with the commenter that exposures to asbestos
are unlikely to occur during the importation process for both
raw commercial chrysotile asbestos and the asbestos articles
evaluated in the Draft Risk Evaluation for Asbestos.
1.16 Ex
josure can occur during importation
51
PUBLIC COMMENTS:
• To conclude that no asbestos exposure occurs during
importation activities is speculation. Risks of accidental
releases and spills exist during importation and
distribution of asbestos-containing products.
See response to Comment 2.41 acute exposure events such as
spills and accidents.
1.17 Other sources or releases
SACC,
51,76,
77
SACC COMMENTS:
• The Draft RE for Asbestos did not include certain
exposure sources (drinking water, talc, asbestos-
containing building materials, vermiculite, etc. as noted
above).
• Fugitive emissions associated with disturbing naturally
occurring asbestos deposits through activities such as
construction should be a COU that is examined in the
asbestos risk evaluation under TSCA.
• Several SACC members searched online and found
information that at least suggests that asbestos-bearing
products are in circulation, including chats, how-to
After reviewing reasonably available information, the
asbestos uses EPA evaluated for Part 1 of the Risk Evaluation
for Asbestos include the import of raw commercial chrysotile
asbestos manufactured domestically into chlor-alkali
diaphragms, sheet gaskets, brake blocks, aftermarket
automotive brakes/linings, other vehicle friction products, and
other gaskets. EPA evaluated the following categories of
COUs for chrysotile asbestos: manufacturing; processing;
distribution in commerce; occupational and consumer uses;
and disposal.
EPA does not consider "naturally occuring asbestos" a
condition of use in Part 1 of the Risk Evaluation for Asbestos
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videos, junkyard parts listings, online advertisements of
wholesale quantities, etc.
PUBLIC COMMENTS:
• In parts of the country with high asbestos levels in rock
formations, air emissions may result from rock mining.
• Urban ambient air concentrations of asbestos have been
documented bv (ATSDR (2001). Asbestos
concentrations in excess of 0.0001 f/cc in urban air
probably represent loading from point sources.
• Over 111,420 metric tons of asbestos were mined in the
United States from 1991 until the last domestic mine
closed in 2002 CUSGS (2006V
• Fibrous amphibole asbestos exposure from natural
sources is a current potential concern, especially in
mining activities as well as earth moving processes such
as dam and road construction and other excavations.
Maintenance and abatement activities also can result in
amphibole asbestos exposure.
because it is not manufactured (including imported)
processed, distributed.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 et al. (9th Cir. 2019), the
Agency will evaluate legacy asbestos uses including asbestos-
containing building materials (ACBM) and associated
disposals of those materials Part 2 of the Risk Evaluation,
beginning with a supplemental scope document.
1.18 Include ingestion route of exposure
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SACC,
31,51,
89
SACC COMMENTS:
• SACC recommended that EPA consider including the
drinking water pathway in the TSCA asbestos risk
assessment.
• EPA has not identified publications that measure water
releases of asbestos associated with processing, using,
or disposing of aftermarket automotive products.
• Another potential source of surface water contamination
is transport of asbestos-contaminated clothing from the
workplace to residence, where laundering the clothing
could release asbestos to domestic wastewaters,
although the contribution overall is likely small.
PUBLIC COMMENTS:
• Commenters requested EPA to expand its risk
evaluation to assess the ingestion route of exposure.
• Ingestion of asbestos-contaminated aquatic animals is
possible. The Draft RE for Asbestos stated that asbestos
is unlikely to bioconcentrate in aquatic ecosystems
based on Belanger et al. (1987) finding that BCFs
measured in clams in the laboratory were low (slightly
>1). However, field-collected clam viscera BCFs of 100
were found, and field-collected whole clam homogenate
BCFs ranged from 1,400 to 5,000. Thus, asbestos does
bioconcentrate in filter feeders such as clams in aquatic
systems. Animals that eat clams (e.g, humans) might
ingest relatively large loads of asbestos in areas where
there is considerable asbestos contamination.
The drinking water pathway for asbestos is currently
addressed under the Safe Drinking Water Act (SDWA),
therefore it was not included in this evaluation, as described
in Section 1.4.4 of Part 1 of the Risk Evaluation for Asbestos.
As stated in the PF, EPA decided to focus its evaluation of
health hazards to lung cancer and mesothelioma. Because oral
exposures (ingestion) are not expected to contribute to the
development of these cancers, this route of exposure was not
considered critical to the evaluation. EPA believes that for the
evaluation of chrysotile asbestos in Part 1 of the Risk
Evaluation, that the inhalation exposures are the most critical
as this is the exposure route that is associated with
mesothelioma, lung cancer, and other cancers that are known
to result from asbestos exposure.
1.19 Acknowledge dermal exposure
SACC
SACC COMMENTS:
• The Draft Risk Evaluation for Asbestos discounts the
dermal exposure pathway by stating asbestos will not
absorb into the body through the protective outer skin
layers (p. 108, In. 3890-3891). However, dermal
EPA acknowledged dermal exposures in the Problem
Formulation document released in 2018. Bodv powders are
not included in any of the relevant COUs identified for
chrysotile asbestos that is the focus of Part 1 of the Risk
Evaluation for Asbestos.
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absorption is assessed for risk assessments involving
body powders containing asbestos. In that situation, the
primary dermal route of exposure to fibers is reported as
being through perineal application of the body powder
(see IARC (2012a); d. 232). This route cannot be
discounted for exposures from the COUs discussed in
this DRE. The DRE should at least acknowledge this
potential dermal pathway.
1.20 Other environmental pathways of exposure
SACC,
51,77,
89, 92,
104
SACC COMMENTS:
• The Draft RE for Asbestos does not address take-home
exposures associated with the transport of asbestos-
contaminated clothing from the workplace to residence,
(see for example, Abelmann et al. (2017)). Several
articles quantify the airborne chrysotile asbestos fiber
levels associated with handling contaminated clothing
in the home. The handling can include laundering the
clothing at home, which could release chrysotile
asbestos to domestic wastewaters, although no studies
are reported to have addressed this possibility.
Recommendation 24: Explain how contaminated
products and articles of clothing will be addressed.
Recommendation 25: Add a "take-home" or
occupational bystander COU and address exposures
associated with the transport of asbestos-contaminated
clothing (and other items) from the workplace to the
home residence.
• Excluding terrestrial pathways based strictly on
statutory considerations will result in an incomplete risk
assessment for asbestos; EPA should consider including
these.
PUBLIC COMMENTS:
• EPA should include other environmental pathways of
exposure including in ambient air (e.g, from stationary
As described in Part 1 of the Risk Evaluation for Asbestos,
EPA ONU assessments evaluate the worker who is not
handling the chemical but is nearby, and ONU exposures are
already addressed throughout the risk evaluation
Regarding the "take home" exposure scenario, scientific
literature has reported on this topic through various protocols,
like shaking clothing with deposited asbestos fibers and then
collecting samples to measure airborne asbestos. However,
EPA notes that:
The publication cited in the SACC report Abelmann et al.
(2017) addresses "take-home" exposures, but the asbestos in
cement dust is not relevant to the COUs considered in the Part
1 of the Risk Evaluation. Specifically, this reference
considered workers using powered abrasive saws to cut
cement pipe over entire shifts, with the pipe containing 35
percent asbestos. The amount of asbestos released during such
conditions is likely dissimilar to releases from the COUs that
OSHA evaluated. Therefore, the results from this publication
(and some similar publications) may significantly overstate
"take-home" exposures for the risk evaluation's COU.
EPA examined take home exposure for the chlor-alkali
industry. This industry's facilities have implemented safe
work practices to dramatically reduce "take-home" exposures.
Specifically, these facilities' locker rooms and changing areas
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sources, incineration, and energy recovery units, outside
chlor-alkali plants), and in solid waste.
• "Take-home" exposure to asbestos—someone working
with asbestos carries fibers on their clothing to non-
occupational settings including home—is a well-
documented exposure pathway.
• Asbestos is not a hazardous waste regulated under
RCRA, and therefore generation, transport, and disposal
of asbestos are not adequately addressed under RCRA.
These exposure pathways should be part of the TSCA-
required risk evaluation for asbestos.
have "clean rooms" separate from "dirty rooms." Outer
clothing and footwear used when handling asbestos is
removed in the "dirty room" and decontaminated or
discarded, thus limiting the amount of "take-home"
exposures; and workers are not allowed to store work clothes
and personal clothes in the same area.
Take-home exposures are possible for other COUs including
auto brake and gaskets. However, the frequency and
magnitude of take-home exposure and contaminations on
clothing and shoes depend on several factors, including
personal hygiene and visibility of the chemical on skin or
clothing. At this point, EPA has not found and does not have
methods to reliably predict take home exposure.
EPA believes it is both reasonable and prudent to tailor TSCA
risk evaluations when other EPA offices have expertise and
experience to address specific environmental media, rather
than attempt to evaluate and regulate potential exposures and
risks from those media under TSCA. EPA believes that
coordinated action on exposure pathways and risks addressed
by other EPA-administered statutes and regulatory programs
is consistent with statutory text and legislative history,
particularly as they pertain to TSCA's function as a "gap-
filling" statute, and also furthers EPA aims to efficiently use
Agency resources, avoid duplicating efforts taken pursuant to
other Agency programs, and meet the statutory deadline for
completing risk evaluations. EPA has therefore tailored the
scope of the risk evaluation for methylene chloride using
authorities in TSCA sections 6(b) and 9(b)(1). EPA did not
evaluate hazards or exposures from chrysotile asbestos
releases to terrestrial organisms or the general population in
this risk evaluation, and as such the unreasonable risk
determinations for relevant conditions of use do not account
for exposures to the terrestrial organisms or the general
population."
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1,21 Potential for co-existing fibrous amphiboles and impurities
SACC,
42, 58,
77
SACC COMMENTS:
• Without extensive testing to indicate otherwise, the
aftermarket brake pads, linings, gaskets, and other
vehicle friction products could contain some
amphiboles, likely in small amounts, that were naturally
intermixed with the chrysotile.
• Recommendation 6: The potential for co-existins
fibrous amphiboles should be mentioned in the
document.
• Of the "asbestos" in past and current commerce, 95% is
chrysotile asbestos; however, the Draft RE for Asbestos
acknowledges that commercial chrysotile can include
small amounts of amphibole asbestos. Thus, asbestos-
containing products in commerce contain both types of
fiber in varying proportions. Some SACC members
objected to a chrysotile-specific risk evaluation.
PUBLIC COMMENTS:
• Populations exposed to commercial chrysotile asbestos
are likely to be exposed to small but variable amounts
of amphibole asbestos which strongly dictates
mesothelioma hazard and influences the risk of
developing an asbestos-related disease.
• Imported chrysotile often contains impurities of other
forms of asbestos. Many imported products containing
talc or vermiculite may also contain amphibole
asbestos.
• EPA collects no information about asbestos-containing
articles or products that could contain impurities.
EPA has included text describing that, as a naturally
occurring mineral, chrysotile can co-occur with other
minerals, including amphibole forms of asbestos. Trace
amounts of these minerals may remain in chrysotile as it is
used in commerce. This commercial chrysotile, rather than
theoretically "pure" chrysotile, is therefore the substance of
concern for Part 1 of the Risk Evaluation for Asbestos.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA 943 F.3d 397. (9th Cir. 2019), the Agency
will evaluate legacy uses of asbestos and associated disposals
as well as other fiber types of asbestos in Part 2 of the Risk
Evaluation for Asbestos. The Agency's risk evaluation for
asbestos will be comprised of both Part 1 (chrysotile asbestos)
and Part 2 (legacy uses and other fiber types of asbestos), and
therefore, is not a chrysotile-specific risk evaluation.
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1.22 Other comments on environmental exposure and release
51, 89
PUBLIC COMMENTS:
• Both the chemical and oil industries may be large users
of asbestos-containing products although EPA lacks
information on the full extent of these uses.
• EPA no longer funds administration of the AHERA
requirements for asbestos in schools, so EPA should
evaluate this exposure pathway.
When preparing the chrysotile asbestos risk evaluation, EPA
obtained and considered the reasonably available information,
defined as information that EPA possesses, or can reasonably
obtain and synthesize for use in risk evaluations, considering
the deadlines for completing the evaluation.
EPA conducted extensive research and outreach to determine
the COUs of chrysotile asbestos and activities that do not
qualify as COUs. This included EPA's review of published
literature and online databases including the most recent data
available from EPA's Chemical Data Reporting program
(CDR), EPA's Toxics Release Inventory (TRI) program,
Safety Data Sheets (SDSs), the United States Geological
Survey's Mineral Commodities Summary and Minerals
Yearbook, the U.S. International Trade Commission's
Dataweb and government and commercial trade databases.
EPA also reviewed company websites of potential
manufacturers, importers, distributors, retailers, or other users
of asbestos.
EPA also considered comments received on the Scope
document, the Problem Formulation, the draft Risk
Evaluation for Asbestos. In addition, EPA convened meetings
with companies, industry groups, chemical users, and other
stakeholders to aid in identifying COUs and verifying COUs
identified by EPA. Although there is some uncertainty
regarding the amount and number of exposed individuals for
the asbestos COUs, EPA believes the remaining asbestos uses
that are imported, processed and distributed are sheet gaskets,
brake blocks, aftermarket automotive brakes/linings, other
vehicle friction products, and other gaskets. These asbestos
uses align with what are listed as asbestos products that
continue to be imported into the U.S. according to the most
recent (2020) USGS Mineral Commodities Summary for
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asbestos found at
https://www.usss.sov/centers/nmic/asbestos-statistics-and-
information.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), the Agency
will evaluate legacy asbestos uses including asbestos-
containing building materials (ACBM), including those that
could occur in school buildings, and associated disposals of
those materials in Part 2 of the Risk Evaluation for Asbestos.
2. Occupational Exposure
Charge Question 2:
2.1 Please comment on the estimation methods and assumptions used for occupational exposure assessment (including ONUs) in
terms of concentration, frequency and duration of exposures, and their use in the risk evaluation. Below are two specific issues in
which EPA is particularly interested in feedback from the SACC.
Incorporation of Short-Term Occupational Monitoring Results
EPA received from industry (or obtained from the published literature short-term (i.e., less than a full 8-hour work shift) monitoring
data for several of the COUs (chlor-alkali, sheet gaskets/stamping, aftermarket automotive parts, and other vehicle friction products).
For these COUs, EPA calculated a separate "full-shift" asbestos exposure estimates as well as a short-term exposure estimate to
account for these occasional, short, high-exposure scenarios. Please comment on the method used.
ONU Exposure Estimates
Based on the readily available information, EPA used different methods to estimate ONU exposures. ONU estimates were made for
each COU; however, the limited information did not allow the development of ONU exposures for short-term exposure scenarios for
chlor- alkali, sheet gasket use, oil field brake blocks, or other gaskets/UTVs. Please comment on the method(s) used (identified
below).
Chlor-alkali (Section 2.3.1.3.5): For ONU exposure estimates area samples were used. Two chlor-alkali facilities provided a total of
15 area samples which were all below the limit of detection (LOD). There were two different detection limits in the two submissions.
Although true exposure values below any limit of detection may be unevenly distributed from zero to the limit of detection, we
assumed that the central tendency exposure concentration estimate is based on one-half of the detection limit for individual samples
and the high-end concentration is based on the highest detection limit across the samples.
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Sheet Gasket Stamping and use (Sections 2.3.1.4.5 and 2.3.1.5.5): EPA did not identify any ONU exposure measurements for these
COUs. However, the literature includes "bystander" exposure studies. Specifically, one publication, Mangold et al. (2006). measured
"bystander" exposure during asbestos-containing gasket removal. The "bystander" locations in this study were between 5 and 10 feet
from the gasket removal activity, and asbestos concentrations were between 2.5 and 9 times lower than those measured for the worker.
Based on these observations, EPA assumes that ONU exposures for these COUs are a factor of 5.75 (i.e., the midpoint between 2.5
and 9) lower than the directly exposed workers.
Oilfield brake blocks (Section 2.3.1.6.5): EPA has not identified specific data on potential ONU inhalation exposures from brake
block use. It is assumed that ONUs do not directly handle brake block and drawworks machineries and that this equipment is always
used and serviced outdoors close to oil wells. Given the limited information identified in Section 2.3.1.6.4 (i.e., worker monitored
values), the lower of the two reported values was used to represent ONU exposures for this COU.
Aftermarket automotive brakes (Section 2.3.1.7.5): EPA has not identified data on potential ONU inhalation exposures from after-
market auto brake scenarios. ONUs do not directly handle brakes and the ONU exposure estimates in Table 2-15 were generated by
assuming that asbestos concentrations decreased by a factor of 8.4 between the worker location and the ONU location. EPA derived
this reduction factor from a publication (Madl et al. (2008) that had concurrent worker and bystander exposure measurements where
the bystander was approximately 5 feet from the worker. The value of 8.4 is the average concentration reduction across four
concurrent sampling events.
Other gaskets/UTYs (Section 2.3.1.9.4): Paustenbach et al. (2006) includes area sampling results that EPA thought appropriate for
ONU exposures. These samples were collected at breathing zone height at locations near the ends of the muffler shop bays where the
exhaust system work was performed. The area sample durations ranged from 25 to 80 minutes, and these samples were collected
during exhaust system work. Overall, 21 area samples from these locations were analyzed by PCM; and 16 of these samples were non-
detects for asbestos. Among the PCM data from this subset of area samples, the authors report that the average asbestos concentration
was 0.005 fibers/cc and the maximum asbestos concentration was 0.015 fibers/cc. The study authors did not report 8-hour TWA
concentrations for the area sample locations. EPA used these average and maximum asbestos concentrations to estimate potential
ONU exposures.
2.2 Please comment on EPA's reasonableness of these assumptions, the uncertainties they introduce, and the resulting confidence in
the occupational exposure estimates (Section4.3.3).
2.3 Please provide specific suggestions or recommendations for alternative approaches, estimation methods, or information sources
that EPA should consider for improving the occupational exposure assessment.
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2.1 EPA's general approach was valid
SACC
SACC COMMENTS:
• Given the relatively high level of uncertainty about
chrysotile asbestos exposure levels associated with the
COUs, EPA has appropriately selected the high
exposure estimates by which to identify risk.
• Absent conclusive state-of-the-science data on the
absence of biologically active chrysotile asbestos in
aftermarket brake drums, the SACC believed EPA's
general approach and evaluation was valid.
EPA thanks the SACC for these comments.
2.2 Su
jport for TSCA definition of asbestos in Draft RE for Asbestos
75
PUBLIC COMMENTS:
• EPA's adherence to the TSCA definition of asbestos in
the Draft RE for Asbestos is strongly supported. As
defined in TSCA, asbestos is the "asbestiform varieties
of chrysotile (serpentine), crocidolite (riebeckite),
amosite (cummingtonite-grunerite), anthophyllite,
tremolite, or actinolite." EPA should continue to adhere
to the TSCA definition of asbestos in the final risk
evaluation.
EPA acknowledges this comment and will consistently apply
this definition in the Risk Evaluation for Asbestos.
2.3 Include legacy and other forms of asbestos in current risk assessment; excluding them underestimates risk
SACC,
25, 45,
47,51,
53, 57,
63, 69,
73, 77,
85, 86,
88, 92
SACC COMMENTS:
• The Draft RE for Asbestos is focused on current
commercial uses of chrysotile asbestos. The SACC
encourages EPA to incorporate into the assessment
other asbestos and asbestos4ike fibers in addition to
chrysotile exposure beyond the COUs evaluated.
• SACC recommended that EPA include exposure to
legacy asbestos to avoid underestimation of risk to
workers, ONUs, and consumers. Without a discussion
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019)), the Agency
will evaluate legacy asbestos uses and associated disposals
of those uses. Legacy asbestos uses are uses for which
manufacture (including import), processing and distribution
no longer occur but the uses are still known, intended, or
reasonably foreseen to occur. EPA will include such uses
and associated disposals in Part 2 of the Risk Evaluation
(legacy uses and other fiber types of asbestos) beginning
with a supplemental scope document.
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of legacy uses, a reader might conclude that legacy uses
do not contribute to population risk.
PUBLIC COMMENTS:
• By not considering exposures to "legacy" asbestos in
buildings and elsewhere, EPA leaves out exposures that
occur to persons not aware of the presence of asbestos
in buildings and other materials and therefore, these
persons are not adequately protected. Legacy asbestos
poses the greatest potential for exposures to asbestos in
the US today. By EPA's own admission, it has
undercounted both exposure and likely mortality rates.
2.4 Future supplemental evaluation for legacy asbestos
SACC,
29, 45,
51,65,
68, 75,
77, 85,
97
SACC COMMENTS:
• Recommendation 16: Explain how lesacv uses of
asbestos will be addressed in the proposed larger
asbestos evaluation.
PUBLIC COMMENTS:
• EPA indicates that they will "consider legacy uses and
associated disposal in a supplemental scope document
and supplemental risk evaluation." However,
completing a separate risk evaluation for legacy uses of
asbestos, while moving forward with risk management
options for chrysotile asbestos is piecemeal regulation
that would underestimate risks associated with
aggregate worker exposure to both current and legacy
asbestos.
• Addressing legacy asbestos in a future supplemental
evaluation raises several questions, particularly because
"exposure to older asbestos is just as dangerous as
exposure to newer asbestos." Would EPA need to
develop IURs for non-chrysolite fibers? How would
those IURs relate to the chrysotile-only IUR?
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), the Agency
will evaluate legacy asbestos uses and associated disposals
of those uses in Part 2 of the Risk Evaluation for Asbestos.
For Part 2, EPA plans to issue the following documents: a
draft supplemental scope document for public comment, a
final supplemental scope document, a draft risk evaluation
document for public comment and a final risk evaluation
document. Prolonging finalization of the risk evaluation for
chrysotile asbestos (Part 1 of the Risk Evaluation for
Asbestos), by expanding the document to also evaluate
legacy uses (where only use and associated disposal is
present) would significantly delay needed risk management
to address COUs where unreasonable risk is present for
chrysotile asbestos.
Part 2 of the Risk Evaluation for Asbestos will include
relevant COUs identified for legacy uses and other fiber
types of asbestos that will be described in a scope document
that will be made available for public comment. EPA will
consider the hazard and risk and appropriate IUR(s) for
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Presumably the future evaluation would address
aggregate or total risk from current and legacy products.
• EPA should clarify whether the phrase "supplemental
documents" simply means the supplemental scope
document and supplemental risk evaluation or whether
it includes other documents too. If the latter, EPA
should specify in the final REA any such additional
documents in which EPA intends to address legacy uses
and associated disposal of asbestos. Further, it is not
clear if the IURs for chrysotile and/or other types of
asbestos will be updated when EPA assesses legacy
uses in the future.
cancer and non-cancer to apply in order to address asbestos
fibers relevant for legacy COUs.
2.5 Need to address aggregate risk of exposures to COUs and legacy asbestos
53, 69,
43, 45,
51
SACC COMMENTS:
• Recommendation 60: Include lesacv and assresate
asbestos exposures in the calculation of exposure and
cancer risk.
PUBLIC COMMENTS:
• EPA should revise the Draft RE for Asbestos to include
all uses and forms of asbestos—particularly "legacy"
asbestos and disposal—and ensure that it estimates the
total [aggregate] risk of asbestos exposure for workers.
Many workers perform tasks daily with no knowledge
of ACM in their work. Labels and safety data sheets are
not present when ACBMs are reused, removed, or
repaired, or disturbed during renovation and demolition
activities. Such workers would not have been trained in
required protection and safety practices.
• Workers and consumers exposed to current chrysotile-
containing products may also have been exposed to
other fibers earlier in their work careers when
construction materials containing these fibers were still
in active use. Determining asbestos risks to these
workers and consumers based solely on their exposure
Section 6(b)(4)(F)(ii) of TSCA requires the EPA, as a part of
the risk evaluation, to describe whether aggregate or sentinel
exposures under the COUs were considered and the basis for
their consideration. The EPA has defined 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)."
The 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)." For this risk evaluation document (Part 1), the
EPA considered sentinel exposure the highest exposure
given the details of the COUs and the potential exposure
scenarios. EPA considered sentinel exposure for chrysotile
asbestos in the form of a high-end level scenario for
occupational exposure resulting from inhalation exposures
for each COU; sentinel exposures for workers are the high-
end 8-hour exposures for sheet gasket stamping without any
PPE.
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to chrysotile in current products would fail to account
for all pathways of exposure and understate risks.
EPA considers the reasonably available information and used
the best available science to determine whether to consider
aggregate or sentinel exposures for chrysotile asbestos. EPA
determined that using the high-end risk estimate for
inhalation risks separately as the basis for the unreasonable
risk determination is a best available science approach.
Aggregate exposures for chrysotile asbestos were not
assessed by multiple routes of exposure in the Part 1 of the
Risk Evaluation for Asbestos (chrysotile asbestos) since only
inhalation exposure was evaluated. Although there is the
possibility of dermal exposures occuring for the chrysotile
asbestos COUs, the only known associated hazard with
dermal exposure to asbestos is the formation of skin lesions,
as discussed in the Scope and PF documents, the only known
hazard associated with dermal exposure to asbestos is the
formation of skin lesions.
EPA estimated full-shift time-weighted averages (central
tendency and high-end) for each COU for the risk
calculation. Since these are full-shift exposure and not task-
based estimates, aggregate exposure is not relevant for the
occupational settings. It is reasonable to assume that the
workers are exposed to asbestos from one COU and that the
high-end air concentration represents the plausible upper
bound of exposure for each COU.
Pathways of exposure were not combined in for chrysotile
asbestos in Part 1 of the Risk Evaluation. Although it is
possible that workers exposed to asbestos might also be
exposed as consumers (e.g, by changing brakes at home), the
number of workers is potentially small. The individual risk
estimates already indicate risk for all conditions of use
except NASA super guppy; aggregating the pathways would
increase the risk. Given all the limitations that exist with the
data, EPA's approach reflects best available science.
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The potential for exposure to legacy uses of asbestos for any
populations or subpopulation, due to activities such as home
or building renovations, as well as occupational or consumer
exposures identified in Part lof the Risk Evaluation, is
possible. EPA will consider these other uses and associated
disposal of asbestos in Part 2 of the Risk Evaluation,
beginning with a draft scope document.
2.6 Concerns about reduced involvement/enforcement of worker-related asbestos regulations
15,45,
69
PUBLIC COMMENTS:
• Excluding legacy ACBMs from the Draft RE for
Asbestos appears to be the prelude to less involvement
of EPA in efforts enshrined in 40 CFR 763 and all its
appendices, including the Asbestos Worker Protection
Rule.
• EPA and OSHA have significant rules in place for
identifying ACM and its management and handling.
EPA has a specific rule, known as the asbestos
NESHAP regulation (40 CFR Part 61, subpart M),
which requires a "thorough inspection" of the
building(s) where renovation or demolition activities
will occur and the prior removal of RACM; however,
this rule is commonly violated.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), the Agency
will evaluate legacy uses and other fiber types of asbestos
uses and associated disposals of those uses in Part 2 of the
risk evaluation. EPA will proceed to risk management for
any unreasonable risks found in Part 2 of the Risk Evaluation
(legacy uses and other fiber types of asbestos). NESHAP
regulations will be appropriately considered in Part 2 of the
Risk Evaluation for Asbestos.
2.7 Need IUR(s) to address all types of asbestos
SACC,
15,25,
29, 43,
45, 46,
47,51,
53, 57,
63, 68,
69, 73,
75, 85,
86, 87,
SACC COMMENTS:
• Recommendation 44: Derive one IUR to aoolv to all
types of asbestos not just chrysotile asbestos. (One
Committee member strongly objected to this
recommendation in post meeting communications.)
PUBLIC COMMENTS:
• The risk evaluation should not be limited to chrysotile
but should encompass all recognized asbestos fibers and
amphiboles because (1) evidence suggests that exposure
to asbestos4ike fibers can also yield unwanted health
EPA is confident that chrysotile asbestos represents the only
form of asbestos where manufacture, import, processing and
distribution in the U.S. is still known, intended, or
reasonably foreseen. The derivation and use of a chrysotile-
specific IUR is necessary to address the COUs included in
Part 1 of the Risk Evaluation for Asbestos. The IUR derived
in Part 2 of the Risk Evaluation for Asbestos will
appropriately reflect other fiber types and health hazards, as
supported by the best available science.
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89,
101,
104
effects (2) real-world exposure is not limited to only
chrysotile.
• In addition to the six commercial asbestos fibers, all
elongated mineral particles (EMPs) are biologically
active in lung and other tissue. Just like commercial
asbestiform fibers, both non-asbestiform fibers and
other EMPs are deadly and cause pleural disease;
asbestosis; other non-malignant respiratory diseases;
lung, ovarian, and laryngeal cancers; and mesothelioma
and should be included. There is no reasonable basis for
EPA to ignore COUs involving occupational talc
exposures and other exposures to EMPs.
• By only evaluating chrysotile and not including the five
forms of legacy asbestos (amosite, crocidolite,
anthophyllite, tremolite, and actinolite) plus Libby
Amphiboles, EPA has underestimated the risk of
exposure to asbestos. Supported by claims of scientists
and epidemiologists, Libby Amphiboles cause cancer
and death, and they are another legacy material form of
asbestos that should be included in any asbestos risk
evaluation by EPA.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), the Agency
will evaluate legacy uses and other fiber types of asbestos
uses and associated disposals of those uses in Part 2 of the
Risk Evaluation for Asbestos, beginning with a draft scope
document. EPA will proceed to risk management for any
unreasonable risks found for the legacy COUs evaluated.
EPA is aware that talc originating from certain sources and
used in consumer and industrial applications may contain
asbestos. However, considering the significant scope of
evaluating the potential risks posed to individuals from
exposure to talc, it would be more appropriate to evaluate
talc (and any known or reasonably foreseen co-located
asbestos therein) in a separate and subsequent risk evaluation
focused on talc.
Libby Amphibole asbestos, which is a mixture of several
mineral fibers such as tremolite and winchite and richterite,
was found in vermiculite ore mined near Libby, MT and
extensively distributed throughout the United States during
the 20th century. Vermiculite from Libby, MT had a range of
commercial applications, the most common of which
included packing material, attic and wall insulation, spray-on
fire proofing, various garden and agricultural products, and
various cement and building products. The Libby, MT
vermiculite mine closed in 1990. EPA will consider whether
such uses of vermiculite originating from Libby, MT will be
included in Part 2 of the Risk Evaluation for Asbestos.
2.8 Legal requirement to address legacy uses
25,31,
45, 68,
77,
101,
73, 53,
PUBLIC COMMENTS:
• EPA has not addressed requirements imposed by the
court in the 2019 Safer Chemicals Healthy Families, et
al. v. U.S. EPA decision relating to "legacy uses" of
asbestos in the Draft RE for Asbestos. TSCA's
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), the Agency
will evaluate legacy uses and other fiber types of asbestos
and associated disposals of those uses in Part 2 of the Risk
Evaluation for Asbestos, beginning with a draft scope
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47,51,
104, 92
definition of 'COUs' clearly includes uses and future
disposals of chemicals; therefore, EPA's exclusion of
legacy uses and associated disposals from the definition
of "COUs" is unlawful.
• In testimony before the US House of Representatives
Energy and Commerce Committee in May 2019, EPA's
assistant administrator for OCSPP conceded that risk
evaluations under TSCA are meant to assess exposures
related to disposal. EPA should consider, for example,
the evidence of significant asbestos waste in the TRI
and the data and reports about active and proposed
Superfund sites. Thus, EPA has, without basis in law or
fact, eliminated from its risk evaluation many
significant sources of chronic exposure to asbestos and
failed to fulfill the mandate of Section 6(b)(4)(A) of
TSCA and contradicts Congress' clear intent. (15
U.S.C. § 2605(b)(4)(A).]
document. Prolonging finalization of the risk evaluation for
chrysotile asbestos (Part 1 of the Risk Evaluation for
Asbestos), by expanding the document to also evaluate
legacy uses (where only use and associated disposal is
present) would significantly delay needed risk management
to address COUs where unreasonable risk is present for
chrysotile asbestos. EPA's Risk Evaluation regulations explicitly
recognize that EPA may reach risk determinations for the
chemical substance under the conditions of use "either in a single
decision document or in multiple decision documents" (40 CFR
702.47).
As explained in more detail in Section 1.4.4. of the Risk
Evaluation, EPA believes it is both reasonable and prudent to
tailor TSCA Risk Evaluations when other EPA offices have
expertise and experience to address specific environmental
media, rather than attempt to evaluate and regulate potential
exposures and risks from those media under TSCA. EPA
believes that coordinated action on exposure pathways and
risks addressed by other EPA-administered statutes and
regulatory programs is consistent with statutory text and
legislative history, particularly as they pertain to TSCA's
function as a "gap-filling" statute, and also furthers EPA
aims to efficiently use Agency resources, avoid duplicating
efforts taken pursuant to other Agency programs, and meet
the statutory deadline for completing Risk Evaluations. EPA
has therefore tailored the scope of the Risk Evaluation for
asbestos using authorities in TSCA Sections 6(b) and
9(b)(1). Additional details included in response to Comment
1.1 are additionally relevant to landfill waste/disposal.
2,9 Methods to estimate past occupational exposures
76
PUBLIC COMMENTS:
• The methods that the EPA used to estimate past
occupational exposures to EMPs for specific cohorts
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seemed reasonable; however, it appears that the high-
end exposure estimations in the analysis represent
probable worst-case historical levels. These worst-case
levels represent a small fraction of the potential range of
exposures for the historical cohorts, which is only
minimally applicable to the current situation.
For high-end exposures, EPA used the best information that
was reasonably available for its estimates. For most
conditions of use, these estimates were based on sampling
data that characterize current worker activities. EPA
defaulted to historical information in the few instances where
current data were not available
2.10 Focus on modern fiber measurements appropriate
46
PUBLIC COMMENTS:
• The risk assessment for the COUs properly focused on
modern fiber measurement assessments and does not
rely on historic dust measurements converted to fiber
counts, especially as these have never been properly
evaluated and verified.
EPA appreciates the comment.
2.11 EPA should use its authority under TSCA to acquire sufficient information to evaluate exposure
77
PUBLIC COMMENTS:
• EPA conceded that it did not obtain important exposure
information, including import volumes of asbestos-
containing products, which sites fabricate imported
sheet gaskets containing asbestos, number of workers
potentially exposed for other non-chlor-alkali plants,
and proximity of workers to exposure sources. EPA
should obtain that information before issuing its final
REA.
• EPA should exercise its Section 8 authority to adopt an
asbestos information gathering regulation. This will
help EPA to fill the data gaps.
EPA did not use its TSCA data collection authorities to
gather additional information regarding asbestos because
EPA believes it had sufficient information to complete the
Part 1 of the Risk Evaluation for Asbestos using a weight of
scientific evidence approach. EPA selected the first 10
chemicals for risk evaluation based in part on its assessment
that these chemicals could be assessed without the need for
regulatory information collection or development. When
preparing this risk evaluation, EPA obtained and considered
reasonably available information, defined as information that
EPA possesses, or can reasonably obtain and synthesize for
use in risk evaluations, considering the deadlines for
completing the evaluation.
To determine the current COUs of asbestos and inversely,
activities that do not qualify as COUs, EPA conducted
extensive research and outreach. This included EPA's review
of published literature and online databases including the
most recent data available from EPA's Chemical Data
Reporting program (CDR), EPA's Toxics Release Inventory
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(TRI) program, Safety Data Sheets (SDSs), the United States
Geological Survey's Mineral Commodities Summary and
Minerals Yearbook, the U.S. International Trade
Commission's Dataweb and government and commercial
trade databases. EPA also reviewed company websites of
potential manufacturers, importers, distributors, retailers, or
other users of asbestos.
EPA also considered comments received on the Scope,
Problem Formulation, and the Draft RE for Asbestos. In
addition, prior to the June 2017 publication of the scope
document, EPA convened meetings with companies,
industry groups, chemical users, and other stakeholders to
aid in identifying COUs and verifying COUs identified by
EPA. Although there is some uncertainty regarding the
amount and number of exposed individuals for the asbestos
COUs, EPA believes the remaining asbestos uses that are
imported, manufactured, processed and distributed are sheet
gaskets, brake blocks, aftermarket automotive brakes/linings,
other vehicle friction products, and other gaskets.
Furthermore, on April 25, 2019, EPA finalized an Asbestos
Significant New Use Rule (SNUR) under TSCA Section 5
that prohibits manufacture (including import) or processing
of discontinued uses of asbestos including asbestos woven
products (other than brake blocks used in oil drilling
equipment) and asbestos cement products from restarting
without EPA evaluating and making a determination on
whether the chemical presents an unreasonable risk to health
and the environment and to take regulatory action, as
appropriate, under Section 5. Since finalization of the
asbestos SNUR in 2019, EPA has not received any
significant new uses notices that would be required prior to
import asbestos woven products (other than brake blocks
used in oil drilling equipment) and asbestos cement products.
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2.12 Characterize the market share of asbestos containing products
SACC
SACC COMMENTS:
• While the effort to characterize the number of
potentially impacted individuals seems thorough, it is
also surprising the number of times EPA merely
declares that a value is unknown. No attempt is made to
characterize even a ballpark estimate. This is important
since in several occupational COUs (specifically
workers stamping sheet gaskets) the numbers exposed
are so small as to suggest that this is a category where
less attention is needed. However, for other
occupational COUs there is insufficient information to
even put bounds on potential numbers of exposed
individuals. It seems that some effort to characterize the
market share of asbestos containing products is
warranted, at least to determine a broad
characterization. As another example, while it may not
be known how many DIYers service asbestos-
containing UTVs, it should be reasonable to estimate
this from the fraction of UTVs with asbestos-containing
parts (a value which is not provided).
• Another concern is the representativeness of the Auto
Parts Warehouse online survey.
• Recommendation 71: Better characterize the market
share of asbestos-containing products and associated
exposed workers.
For every occupational exposure COU, EPA estimated the
number of exposed workers and ONUs. Some estimates
could be made to a high degree of accuracy, while others
involved greater uncertainty. In all cases, EPA used the best
available information to derive these estimates and
acknowledged uncertainties where appropriate. Some
comments EPA received (like this one) suggested that some
numbers of exposed workers were underestimates, and other
comments indicated that some numbers were overestimates.
To be responsive to these comments, EPA revisited every
estimate made in the draft risk evaluation. Some changes to
numbers were made (e.g, ONU estimate for the aftermarket
brakes COU in Section 2.3.1.7.4) after further reflection on
the methods and the input that EPA received.
EPA has not indicated the fraction of UTVs with asbestos-
containing parts because doing so could potentially result in
the release of confidential information. In coordination with
Customs and Border Protection (CBP), EPA reviewed
available import information. CBP provided import data for
asbestos HTS codes in CBP's Automated Commercial
Environment (ACE) system, which identified 26 companies
that reported the import of asbestos-containing products
between 2016 and 2018. EPA contacted these 26 companies
in order to verify the accuracy of the data reported in ACE.
Three companies confirmed that the asbestos HTS codes
entered in ACE were correct corresponding to the uses of
asbestos gaskets, brake linings and rubber asbestos sheets
used to make gaskets. One of the companies indicated that it
used asbestos gaskets in producing UTVs. EPA has
limitations on its use of specific information from ACE,
including the identities of the companies. Specific ACE
information can only be used internally within EPA and
cannot be discussed or shared with anyone outside of the
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Agency. While EPA is not indicating the fraction of UTVs
with asbestos-containing parts, EPA was still able to reach a
risk determination for the associated COU.
For oil field brake blocks, EPA received direct confirmation
of U.S. companies importing asbestos-containing oil field
brake blocks for domestic use (as explained in Section
2.3.1.6.1 of the draft risk evaluation). However, EPA did not
receive information on the market share of asbestos-
containing brake blocks. In its comments on asbestos-
containing automotive parts, the SAAC stated that"... the
availability ... is unclear and a default to reasonable worst
case taken by the Agency would appear to be warranted" and
"The DRE has, like all prudent assessments, traded
conservatism when data are unavailable. That is, when the
information is not definitive, it has defaulted to reasonable
worst-case estimates." EPA has taken a similar reasonable
worst-case approach for the market share of asbestos-
containing oil field brake blocks.
Regarding the representativeness of the Auto Parts
Warehouse online survey, EPA does not have other sources
of information on DIYers that perform their own brake work.
The Agency considers the Auto Parts Warehouse survey to
be reasonably available information, defined as information
that EPA possesses, or can reasonably obtain and synthesize
for use in risk evaluations, considering the deadlines for
completing the evaluation.
2.13 Low occupational exposures (multiple COUs)
39, 42,
61
PUBLIC COMMENTS:
• Commenter found no information in the document that
oil field brake blocks have contained asbestos over the
past 35 years. Even if true, it seems this analysis is not
warranted under the Lautenberg initiative. If it were,
given the low number of persons who could be
EPA identified the oil field brake block COU in the Scope
document and received no comments at the time about the
appropriateness of this COU. EPA believes asbestos-
containing oil field brake blocks continue to be used for
older oil rigs based on consultations with industry
representatives with knowledge of the oil field drilling
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potentially exposed and the magnitude of possible
exposures, regulatory action is unwarranted, especially
considering such a critical use scenario where the
failure of such materials can result in multiple injuries
to workers.
The majority of the document describes scenarios that
will likely rarely occur in the coming years and, if they
do, the number of persons potentially exposed is
vanishingly small and below regulatory significance.
The exposure concentration data are clear and
consistent: mechanics and persons working with and
around AABL are exposed only to low levels of short-
fiber chrysotile, at concentrations well below even
today's PELs (e.g, Finlev et al. (2007): Boyles et al.
(2019)).
There is no exposure to asbestos during the installation
of brakes, even if there were asbestos-containing brakes
used, as there is no brake grinding needed on a modern
car. Additionally, all the new cars would have disc
brakes. Since as few as 100 persons may be exposed,
no cancer deaths are expected.
Because the demand is so low and because no facility
wants asbestos-containing gaskets on their site (except
chlor-alkali facilities or a refinery), it is not surprising
that only one employee in the US is involved in
punching gaskets.
The number of plausibly exposed automobile
mechanics is probably less than 30-100 persons in the
United States (if any).
Commenter believes that virtually no workers will be
handling asbestos-containing clutches in the coming
years in the US and recommended dropping the
scenario.
industry. As Section 2.3.1.6.1 of the draft risk evaluation
notes, EPA received direct confirmation of U.S. companies
importing asbestos-containing oil field brake blocks for
domestic use. Therefore, EPA is justified in retaining this
COU in the final risk evaluation.
Part 1 risk evaluation is based on uses of chrysotile asbestos
for which there is known, intended, or reasonably foreseen
import, processing, or distribution. COUs are not limited
based on anticipated future trends.
EPA made adjustments to the estimated number of
individuals exposed by the limited available information on
the potential market share of chrysotile asbestos brakes.
Details are provided in Section 4.3.7: Confidence in the
Human Health Risk Estimations, but the new estimate for
number of both workers and ONUs assumes that asbestos
brakes represents approximately 0.05% of aftermarket
automotive brakes. EPA estimated potentially exposed
individuals (both worker and ONUs) applying this factor
(0.05%) to the universe of automotive service technicians
and mechanics.
EPA identified information to indicate that replacement
drum brakes and brake shoes are readily available from U.S.
auto parts stores, and there are many popular instructional
videos online explaining how to replace drum brakes. Many
of the instructional videos deal specifically with cars that are
model year 2000 or later, so DIYers are clearly interested in
changing drum brakes in more recent vintages, not just
antique automobiles. If a small percentage of drum brakes
are imports that contain asbestos, there could still be
numerous workers and DIYers exposed to asbestos.
EPA further notes that the California Air Resources Board
found that brakes from 3% of tested vehicles contained
chrysotile asbestos in the rear drum brakes (De Vita et al.
(2012). The vehicle model years ranged from 1989 to 1998
and based on high mileage and/or confirmation by vehicle
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owners, all vehicles with asbestos brakes were assumed to
have had their brakes replaced at least once, thereby
indicating a high probability of an aftermarket source of the
brake linings. Several of the vehicle owners indicated they
had maintenance performed at a service station or
independent garage.
While California and Washington state subsequently limited
sales of asbestos-containing aftermarket brake parts
(California Health and Safety Code sections 25250.50 et
seq.; and Revised Code of Washington, Chapter 70.285.), the
state laws allow the sale until 2025 of brakes exceeding the
concentration limit if they were produced prior to 2015.
Also, brake friction material manufactured as part of an
original equipment service contract for vehicles
manufactured prior to 2015 are exempt. The California and
Washington laws also exempt brake friction materials used
in: motorcycles; military vehicles; race cars and other off-
road vehicles (e.g, farm equipment, logging equipment, etc.);
collector vehicles (those over 30 years old); parking brakes;
and motor vehicles employing internal-closed-oil-immersed
motor vehicle brakes or similar contained brake systems.
Moreover, certain manufacturers may also apply for an
exemption from the state requirements. And while a
Memorandum of Understanding (MOU) between EPA and
industry stakeholders adopted the California and Washington
limitations, the MOU does not cover products that are
exempted by California and Washington
(https://www.epa.sov/sites/production/files/2015-
11/documents/coDDer brakeoads mou.Ddf). In addition, the
MOU is not legally enforceable against the signatories to the
MOU, their members, or any other parties. While the
California and Washington laws and the federal MOU may
have reduced the prevalence of asbestos-containing brakes in
the U.S., they do not preclude continued exposures to
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asbestos from automotive brakes/linings and other vehicle
friction products.
2.14 Calculation of full-shift (8-hour) exposures using short-term, peak occupational exposures
16,41,
42, 70,
79, 90,
100
PUBLIC COMMENTS:
• Peak exposure data cannot be used to predict full-shift,
task-duration, or even short-term concentrations.
• The duration of potentially high exposure actions is
usually minutes, rather than hours or days; therefore, the
8-hour TWA of these exposures would be diminishingly
small.
• While not all activities may be performed during a
particular shift, it is reasonable to assume that long-term
monitoring data, such as is available for the chlor-alkali
industry, provides an accurate representation of
exposure during a typical shift. Calculating 8-hour
TWA concentrations using a combination of short-term
exposure data and full-shift data incorrectly assumes
that exposures represented by the full-shift data are
exclusive of exposures represented by the short-term
data.
• Additionally, EPA's evaluation mischaracterizes the
data in the text and presented in Table 2-7 by focusing
on the maximum short-term value from preliminary data
submitted by ACC. ACC and member companies have
since provided additional information including the
specific task descriptions and exposure data as well as
full shift exposure data which represents exposures
through the entire shift, including short term tasks.
• The Draft RE for Asbestos incorrectly compares the
short-term data to the OSHA 8-hour TWA of 0.1 f/cc.
EPA used a method to incorporate short-term data into an
estimate of full-shift exposures; EPA did not extrapolate the
short-term concentration values into an 8-hour shift. The
methodology used the appropriate 30-minute value (i.e.,
central tendency or high-end) and incorporated it into a
revised 8-hour value (again, using central tendency or high-
end). For example, the first two scenarios show the values
for the chlor-alkali scenario and the third row shows the
value that would be a true extrapolation of the 30-minute
value to an 8-hour value:
Scenario: 8-hour Full Shift
Central 0.0049
High-End 0.034
Scenario: 8-hour Full Shift with appropriate 30-minute short-
term value incorporated into the 8-hour time frame
Central 0.061
High-End 0.0639
Scenario: 8-hour Full Shift with appropriate 30-minute short-
term value extrapolated to the 8-hour time frame
Central 0.024
High-End 0.512
Based on information received during the public comment
and peer-review period, EPA updated the chlor-alkali data in
Section 2.3.1.3.4. Updates reflect clarifications received
from ACC on important details of their original data
submission that were not previously available to EPA.
EPA agrees that a comparison should not be made between
short-term asbestos concentrations and OSHA's 8-hour
TWA PEL. It appears this comparison was only made in
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lines 2247-2248 in Section 2.3.1.3.2 the draft risk evaluation.
EPA removed that text from Part 1 of the Risk Evaluation for
Asbestos.
Additionally, as noted in Section 5.2, "The Agency also
considered that the health effects associated with asbestos
inhalation exposures are severe and irreversible. These risk-
related factors resulted in EPA focusing on the high-end risk
estimates rather than central tendency risk estimates to be
most protective of workers, ONUs, consumers, and
bystanders." In keeping with this decision, EPA concluded
that it would be prudent to assume that the short-term
samples may not simply represent the high end of the
sampling distribution for full-shift sample and thus decided
to include the short-term sample concentrations into a
revised 8-hour TWA to ensure that the short-term samples
were represented in risk characterization and risk decisions.
The three observations that: 1) the full-shift and short-term
samples are not taken concurrently; 2) the task-specific
sampling data are not randomly ascertained; and, 3) the
weighted average of the median values of the task-specific
short-term samples is almost as large as the 95th% of the
full-shift tasks in Table 2-5 (0.03 vs 0.034 f/cc), strongly
suggest that these short-term data do not fall withing the
sampling distribution of the full-shift samples.
While it is possible that these short-term samples could be
samples within a full-shift and thus averaging them into a re-
weighted 8-hour TWA might be considered inappropriate,
the short-term samples were not recorded on the same dates
as the full-shift samples according to Occidental Data, see
Volume 2, so it is clear that the short-term data were not
sampled concurrently within the full-shift samples. Further,
the short-term samples appear to represent targeted tasks that
do not represent full-shift activities.
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The short-term sample concentrations from the chlor-alkali
industry are higher than the full-shift values. According to
Table 2-4 which summarizes the 30-min short-term personal
breathing zone samples from two of three companies in the
chlor-alkali industry, the median concentration is 0.024 f/cc
and the 95th% is 0.512 f/cc. According to Table 2-5 which
summarizes the full-shift personal breathing zone samples
from all three companies, the median concentration of full-
shift samples is 0.0049 f/cc and the 95th% is 0.034 f/cc.
Table 2-7 summarizes the ACC Short-Term PBZ Sampling
Data by Exposure Group (samples from 2001 to 2016) by
task and shows that the tasks are sampled unevenly with the
overwhelming preponderance of samples taken from the
'Glovebox Weighing and Asbestos Handling' which
accounted for 150 of 326 samples (46%) even though that
task was one of seven specific tasks (14%). The weighted
average of the task-specific short-term samples from Table
2-7 is 0.03 f/cc - which is higher than the median
concentration of short-term samples in Table 2-4 (0.03 vs
0.024 f/cc).
2.15 Reduction factors used for indoor bystander exposure are reasonable but inconsistent
SACC COMMENTS:
• Given the high variability in the bystander exposure, the
reduction factors (RFs) in the Draft RE for Asbestos for
indoor use appear to be reasonable. Using an outdoor
factor of 10, however, would likely produce an
exposure estimate that is a substantial over-estimate of
bystander exposure. It should be considered as an upper
bound estimate and used accordingly. One SACC
member suggested that a more accurate estimate could
be derived using previous research demonstrating how
to estimate airborne concentration fall-off outdoors as a
function of air speed (Shade and Javiock (1997).
EPA received several comments about the approach used for
ONU exposure estimates. As a result, EPA reevaluated its
approach for each COU. For aftermarket automotive
brakes/linings, EPA determined that the NIOSH sampling
studies (mostly from the 1980s) include direct measurements
that could be used to characterize ONU exposures. EPA
updated the ONU exposure estimates for this COU
accordingly in Section 2.3.1.7.5.
For the other COUs for occupational exposures, only one
"reduction factor" is now used. EPA continues to believe this
is the best approach in the absence of direct measurements.
EPA updated the text in Section 2.3.1.4.5 and 2.2.1.4.6 to
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• The RF of 10 for bystanders outdoors for brake repair
seemed to be rounded up from the value of 6.5
calculated from one data source. Then the Draft RE for
Asbestos (p. 114) mentions using a bystander RF of
5.75 for a gasket installation scenario using a value
derived from an occupational study. Another statement
(Draft RE for Asbestos p. 120) states that EPA did not
use an RF for gasket repair/replacement because there
were sampling data available. The approach does not
show a consistent decision process and as a result the
discussion was found to be somewhat confusing.
Recommendation 32: Clarifv the reduction factor (RF)
discussion for bystanders.
PUBLIC COMMENTS:
• With three different approaches for estimating exposure
RFs for ONUs and bystanders in the Draft RE for
Asbestos, EPA's "consistency" in satisfying the weight
of the scientific evidence requirement is unclear. The
final RE A needs a clear rationale for how the RFs
reflect "reliable and unbiased" science. EPA should
provide a "pre-established protocol" to..." consistently"
identify and evaluate each stream of evidence,
commenter recommended that EPA take a more
uniform approach and believes that averaging would
best capture the available monitoring data.
• EPA incorrectly assumes ONUs are exposed for 8 hours
per day and 250 days per year for 40 years, which far
exceeds reality. ONUs including supervisors/managers
and janitorial workers are unlikely to stay near work
zones throughout an entire day. Accordingly, EPA must
appropriately and significantly reduce the TWF to
account for the actual duties of ONUs.
explain this selection and acknowledge the associated
uncertainties.
The term bystanders is often used in consumer settings
whereas ONU is used for occupational settings. For
occupational exposures, the most appropriate ONU exposure
assessment approach depends on the available information.
For each COU EPA reviewed the reasonably available
information, including air monitoring and exposure
assessment approaches. EPA selected the most appropriate
estimation method based on the strength, limitation and the
relevance of the data.
EPA agrees that in some cases ONU may not be exposed at a
full shift, every workday. EPA included statements
acknowledging this possibility in all COUs except for the
NASA Super-Guppy which EPA assumed 12 hours/year of
exposure.
ONU exposure is likely to vary depending on COU, sites,
and what tasks are assigned to ONUs. The information EPA
reviewed since issuing the draft risk evaluation supported
revisions to the ONU exposure estimates for aftermarket
automotive brake and brakes installed in exported cars.
EPA used a consistent hierarchy to derive occupational
exposure estimates, whether for workers or ONUs which is
described in Section 2.3.1.3.6. EPA's preferred approach
was to use representative monitoring data of a known and
high quality. When such data were not reasonably available,
EPA considered other sources of information, including the
extent to which reasonable estimates could be derived. This
approach was uniformly applied across the COUs.
After applying this hierarchy, the occupational exposure
assessment now includes two different approaches for
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estimating ONU exposures: direct monitoring data (typically
area samples) and application of reduction factors.
Monitoring data was used to estimate ONU exposures for all
COUs except for the two conditions of use pertaining to
sheet gaskets, for which reduction factors were used.
Specifically, for sheet gasket fabrication and use, EPA relied
on literature that measured asbestos concentrations at
"bystander" locations that were between 5 and 10 feet from
the gasket removal activity; at these locations, asbestos
concentrations were between 2.5 and 9 times lower than
those measured for the worker. The details of the estimates
are in section 2.3.1.4.4 of the risk evaluation.
2.16 Reliance on industry-reported practices could result in bias
31, 73
PUBLIC COMMENTS:
• EPA determined that several COUs did not constitute an
unreasonable risk. However, those conclusions are
predicated on information received from the regulated
community itself, and the commenters are skeptical
about self-reported compliance. They suggested that
EPA adjust industry-reported compliance and practices
observed during announced site visits to account for the
more likely routine practices. For example, during one
site visit, a consultant noted in a footnote that: "unused
scrap pieces of reportedly ACM were placed in a
dumpster with other waste and disposed with normal
plant waste," although that practice is not permissible.
• EPA should assume that industrial hygiene sampling
results represent the best-case scenario in that
workplace. If a site visit is announced, employers can
modify the usual work environment to reduce the
concentration of a contaminant. Many workers report
that their worksite is cleanest when an OSHA inspector
When preparing the chrysotile asbestos risk evaluation, EPA
obtained and considered the reasonably available
information, defined as information that EPA possesses, or
can reasonably obtain and synthesize for use in risk
evaluations, considering the deadlines for completing the
evaluation. EPA looked at reasonably available information
and determined that the monitoring data provided by
industry was the highest quality data available. All studies
used in the Risk Evaluation, including industry submissions,
are evaluated using the same data quality criteria under the
TSCA Systematic Review process described in the
document, Application of Systematic Review in TSCA Risk
Evaluations. In consideration of comments received, EPA is
in the process of updating the TSCA Systematic Review
protocol to improve the transparency of this review process
and further reduce possible bias such that all studies are
appropriately considered.
EPA is not aware of any scientifically defensible adjustment
factor that could be used for this purpose. When using
industry-supplied data, EPA sought independent lines of
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(or an insurance adjuster, safety consultant, corporate
official, or investor) is on the premises.
evidence (e.g, observations during site visits, concordance
with trends reported in the literature) to validate the
information provided by industry.
2.17 General comments on COUs (COUs) for occupational exposure
SACC,
42,51,
53, 65,
68, 74,
83, 92
PUBLIC COMMENTS:
• EPA grossly overstates the potential number of exposed
workers and ONUs in most or all COUs.
• The Draft RE for Asbestos lacks meaningful exposure
monitoring data for nearly all the COUs it addresses.
The sparseness of the monitoring data is surprising
considering the longstanding concern about the risks of
industrial use of asbestos.
• ACC urges EPA to revise the Draft RE for Asbestos to
include COU and associated exposure levels that
accurately represent realistic conditions, rather than
extreme, unrealistic usage.
• The number of workers that might plausibly be over-
exposed, beyond the OSHA PEL, is virtually zero.
EPA estimated the estimated number of individuals exposed
using reasonably available information on the potential
market share of asbestos brakes. Details are in provided in
Section 4.3.7: Confidence in the Human Health Risk
Estimations. The new estimate for number of both workers
and ONUs assumes that asbestos brakes may represent only
approximately 0.05% of aftermarket automotive brakes. EPA
estimated potentially exposed individuals (both worker and
ONUs) by applying this factor (0.05%) to the universe of
automotive service technicians and mechanics.
One comment pertains to the sparseness of occupational
exposure monitoring data. EPA took extensive measures to
identify the reasonably available information per TSCA
section 26(k) to support the risk evaluation. That included
obtaining data from the systematic review process and from
the affected industries. Additionally, the public comments
and peer review comments included several hundred
references—all of which EPA reviewed for additional
occupational exposure monitoring data for use in the risk
evaluation.
The last comment pertains to the extent to which today's
workers are exposed to chrysotile asbestos above the OSHA
PEL. The comment does not provide any supporting
information. Evaluation of compliance with OSHA's
asbestos standard and the protectiveness of the asbestos PEL
is not the purpose of the risk evaluation.
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2.18 Limited submissions by industry/publicly available information for COUs
SACC5
1,63,
86
SACC COMMENTS:
• In the "components of occupational health exposure
assessment" that EPA sends to companies with a
request for data, EPA does not ask for descriptions of
exposure monitoring/surveillance protocols. Thus,
sampling/monitoring program plans and/or individual
company strategies are not presented in the Draft RE for
Asbestos, and it was unclear whether companies having
workers engaged in asbestos COUs were specifically
requested to submit such descriptive data. Without a
description of the sampling strategy and how employee
duties were monitored, one cannot determine the
completeness and representativeness of facility worker
exposure data. The SACC found it difficult and
problematic to review the data inclusion/exclusion
decisions that are inherent in the Draft RE for Asbestos
exposure assessment.
• In the descriptions of many of the COUs, the Draft RE
for Asbestos mentions studies but did not describe
findings from these studies. These studies may have
been performed too far in the past or are otherwise
inappropriate. These data might be inappropriate for
direct use but would provide a comparison to see how
results have varied over time and, if current data are not
available, could provide a "worst case" source of data
that could be used. Some SACC members suggested
that international data (from countries that have not yet
banned or restricted asbestos) appeared to be
underutilized.
• The Draft RE for Asbestos used very few studies from
the peer-reviewed published literature to estimate
asbestos exposure in some COUs. This is especially true
of exposure associated with repair and/or replacement
EPA made numerous efforts to gather supporting
documentation (e.g, sampling plans, sampling reports, etc.)
for the occupational exposure data on the identified COUs
included in Part 1 of the Risk Evaluation for Asbestos. For
some COUs, particularly the studies of auto break
mechanics, the underlying literature thoroughly documented
study objectives, methods, results, and limitations; and EPA
reviewed this information early in the risk evaluation process
as part of its systematic review procedures. For other COUs,
detailed background information mentioned in the comments
such as sampling plans and data handling methods, was not
available. For example, for the chlor-alkali industry and for
sheet gaskets, the data EPA used in Part 1 of the Risk
Evaluation came from employers' worker monitoring, which
evidently was conducted in fulfillment of OSHA's asbestos
standard. The OSHA asbestos standard has worker exposure
monitoring requirements, but that standard does not
prescribe development of sampling plans and data handling
methods. Accordingly, a complete account of the sampling
strategy for some data sets is not available, but EPA did
confirm other important details for those data sets (e.g,
sampling methodology used, type of sample collected,
worker activities conducted during the sampling).
For 9 Chlor-alkali facilities EPA received the following
information in addition to the air samples: representative
regulatory compliance controls, representative asbestos
handling process flow diagram, and representative asbestos
dust collector preventative maintenance process for
semiannual annual inspection.
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of brakes where one or two studies are referenced and
used in the relevant portions of the DRE.
PUBLIC COMMENTS:
• Once commenter commended EPA's use of industry
monitoring data for several COUs; however, for some
COUs EPA lacked information about the
representativeness of the data it used. For other COUs,
EPA's assumptions are not realistic and therefore may
not meet the "reasonableness" or "relevancy"
requirements of best available science.
• The evaluation relies on limited submissions by industry
and publicly available information to identify ongoing
COUs and to determine the magnitude of current
exposure. (86-11) The data for some COUs were very
sparse and often did not identify the actual tasks being
performed by the workers who were sampled; therefore,
it is unclear if 'worst case' or even 'high-end' exposure
scenarios were considered. (63-8)
• Only two workers were identified for stamping sheet
gaskets, and only two US. Ti02 manufacturing facilities
were identified that use asbestos-containing gaskets.
EPA is not certain if asbestos-containing sheet gaskets
are used in other industries and to what extent. For the
other COUs, EPA has no estimates of the number of
potentially exposed workers. EPA acknowledged that,
outside the chlor-alkali industry, there is no information
on the market share of AC products available to workers
and consumers. Overall, EPA received only a
"handful" of voluntary submissions from industry.
The compilation of underlying data is included as a
supplemental document and the original submissions are
available:
https://www.regulations.gov/document?D=EPA-HQ-OPPT-
2016-0736-0103
https://www.regulations.gov/document?D=EPA-HQ-OPPT-
2016-0736-0129
https://hero. epa.gov/hero/index. cfm?action=search.view&ref
erence id=5352390
https://www.regulations.gov/document?D=EPA-HQ-OPPT-
2016-0736-0106
All information received were reviewed in detail and
relevant information incorporated in Part 1 of the Risk
Evaluation for Asbestos.
Another issue suggested that EPA did not fully utilize
available data, including those from the international
community. For most COUs, EPA intentionally focused on
data from the U.S., because OSHA's asbestos standard
includes provisions that apply to U.S. workers and
worksites—and these provisions do not apply in other
countries. Responses to other comments document EPA's
recent research into data from European Union chlor-alkali
facilities. Given concerns about data representativeness, EPA
will not incorporate additional data from foreign countries in
the draft risk evaluation (though some text in Sections
2.3.1.3.4 and 2.3.1.7.4 has been revised to acknowledge
EPA's awareness of such data for certain COUs). Additional
information and why EU information was not used is in the
response to Comment 2.20 Chlor-alkali occupational
workers exposure estimate.
A comment correctly notes that EPA used very few studies
from the peer-reviewed literature for aftermarket automotive
brakes/linings. As explained in the draft risk evaluation, EPA
considered publications since 1980 that were conducted in
the U.S. and that presented original compilations of
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occupational exposure data. Many of the publications in the
peer-reviewed literature since that time summarize data
presented in earlier publications and do not present original
data.
A final comment pertains to the estimated number of
workers for each COU. As noted in responses to other
comments, EPA reviewed all relevant exposure information
found for each COU and selected the most relevant
information to estimate the workplace air concentrations.
The review and selection of references is broadly described
in our systematic review process.
2.19 EPA should use its TSCA information collection authorities
SACC,
51,85,
86
SACC COMMENTS:
• EPA acknowledged that the data they received
voluntarily from various companies might not be
representative of all tasks and all facilities and that they
were uncertain about the numbers of exposed workers.
The direction and magnitude of some of the
uncertainties were not described. EPA should use its
TSCA powers to obtain missing critical information.
• Recommendation 68: Reciuire reDortins of numbers of
potentially exposed workers and other critical missing
data from industrial facilities that process asbestos.
(SACC-169)
• The Draft RE for Asbestos was hampered by lack of
data for specific COUs. For example, in Draft RE for
Asbestos section 2.3.1.4., Sheet Gaskets, EPA indicated
that there were no surface wipe sampling data
"available to characterize the extent of settled dust and
asbestos fibers present during this operation." (SACC-
77) For the chlor-alkali industry it was unclear if certain
high-exposure activities were associated with the air
monitoring results. Recommendation 26: EPA should
EPA did not use its TSCA data collection authorities to
gather additional information regarding asbestos because
EPA believes it has sufficient information to make a
reasoned analysis in light of the limited time available under
the statute for completing the risk evaluation. EPA had
sufficient information to complete the Part 1 of the Risk
Evaluation for Asbestos using a weight of scientific evidence
approach. EPA selected the first 10 chemicals for risk
evaluation based in part on its assessment that these
chemicals could be assessed without the need for regulatory
information collection or development. When preparing this
Part 1 of the Risk Evaluation for Asbestos, EPA obtained
and considered reasonably available information, defined as
information that EPA possesses, or can reasonably obtain
and synthesize for use in risk evaluations, considering the
deadlines for completing the evaluation.
When reviewing publications specific to aftermarket
automotive products, EPA intentionally limited its evaluation
to studies that examined exposures at U.S. business
establishments. This focus was due to the fact that OSHA's
asbestos standard includes provisions that apply to U.S.
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use its statutory authority under TSCA to request
additional data on occupational exposures to fill
knowledge gaps.
PUBLIC COMMENTS:
• Some commenters agreed with SACC that EPA should
use its statutory authority under TSCA to obtain reports
from industry on ongoing imports, uses and exposures
for asbestos and asbestos-containing products. One
commenter laid out the history of the 2018 petition by
six organizations to EPA requesting that EPA
promulgate reporting requirements for asbestos under
the information collection authorities in section 8(a) of
TSCA. A similar petition was filed again in 2019 by 18
Attorneys General (AGs) representing 17 states and the
District of Columbia. The Draft RE for Asbestos suffers
from the exact same information gaps identified in the
2018 petition and expressly acknowledges the gaps, just
as the earlier problem formulation did.
workers and worksites—and these provisions do not apply in
other countries. Additionally, the profile of brakes and
clutches encountered in U.S. vehicles differs from what is
seen in other countries. For these and other reasons, EPA
scientists read studies of workers in Colombia, Iran, and
many other countries, but the risk evaluation focuses on the
asbestos measurements specific to conditions in U.S.
establishments. Lines 3387-3388 in Section 2.3.1.7.4 of the
Draft Risk Evaluation for Asbestos explained EPA's
approach, which ".. .focused on post-1980 publications that
reported original asbestos PBZ measurements for business
establishments in the United States." EPA will expand upon
the text in this section in the final Risk Evaluation for Part 1.
For the comment on surface wipe data, EPA contends that
surface wipe sampling data are not essential for evaluating
inhalation exposures. These data, were they available, would
only confirm the presence or absence of airborne asbestos—
they would not quantify airborne concentrations.
One comment indicates that the chlor-alkali sampling data
might not have captured certain high-exposure activities. The
sampling data do account for certain high-exposure activities
(e.g, hydroblasting). However, the methods for measuring
airborne asbestos are not continuous, and EPA is not aware
of any industry that has continuous asbestos monitoring data
that would capture every peak exposure event. EPA
acknowledges in Section 2.3.1.3.6 of the Risk Evaluation
that some high-exposure events might not be reflected in the
data.
The following sentence was added to Section 2.3.1.7.4 to
highlight the focus of EPA's search for exposure data: "EPA
focused on U.S. business establishments due to the
availability of measurements and the fact that OSHA's
asbestos standard mandates controls and other safe work
practices that do not apply in other countries."
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2.20 Chlor-alkali occupational worker exposure estimates
SACC,
35, 42,
51,70,
73,91,
108
SACC COMMENTS:
• The chlor-alkali industry is the only COU under
evaluation that had considerable air monitoring data,
having data for both full shift and short-term exposures.
Public comments confirmed what the Draft RE for
Asbestos reports, that the ACC-submitted data might
have duplicated the individual company submissions
(see p. 66, In. 2347-2349). Despite the duplication
concern, the Draft RE for Asbestos rates the data set as
excellent and the exposure determination is given a high
level of confidence. The SACC recommended that
duplicates be identified and be removed, and the
analyses be redone.
• SACC found that there were chlor-alkali industry
asbestos exposure studies conducted historically that are
not described or referenced in the Draft RE for
Asbestos. The paper bv Strokova et al. (1998)
referenced in Section 2.1.1.4.4. (sheet gasket stamping
inhalation) has sampling data from a "diaphragm
electrolysis shop" that might be useful for comparison.
While it is understandable that these studies are not used
directly, they could provide perspective as to whether
exposures have changed or not. International data may
also be available as the EU chlor-alkali industry is not
expected to replace the use of asbestos until 2025.
• Recommendation 18: If EPA has not done so, it should
query EU sources to determine if additional asbestos
exposure study data are available.
• In the chlor-alkali industry, EPA used industry-supplied
data to estimate exposures in sheet gasket use even
though those data did not include sample duration or
how long gasket removal was performed (Draft RE for
Asbestos page 79). Recommendation 75: Limit
EPA was made aware that ACC submitted chlor-alkali
occupational exposure data that were duplicative of other
data submissions. ACC confirmed this duplication after the
draft risk evaluation was issued. EPA has since removed the
duplicate data, and the final risk evaluation will be based
only on original data points. EPA included text in Section
2.3.1.3.4 to explain this issue.
Another comment suggested that EPA review the Strokova
et al. (1998) publication for relevant data for the chlor-alkali
COU. That study documents asbestos sampling from two
Bulgarian manufacturing facilities in the mid-1990s. One of
the facilities evidently manufactured asbestos-containing
electrolysis diaphragms. The paper reports the range of
breathing zone concentrations observed, and this range falls
within the range of data that EPA compiled from U.S.
facilities. Therefore, the paper does not change EPA's
assessment. EPA did not add details on this paper to the
chlor-alkali section, because the study was conducted in
Bulgaria more than 25 years ago, using sampling and
analytical methods that differ from those used in the United
States.
Regarding the recommendation that EPA seek information
from the EU on occupational exposures to chrysotile
asbestos in the chlor-alkali industry, a limitation in any such
comparison is that exposure data from EU facilities may not
be representative of the U.S. manufacturing environment,
due to differences in process design, production levels,
ventilation practices, regulatory frameworks, and other
factors. Another complicating factor is that, as of 2014, all
but one chlor-alkali facility in the EU had phased out use of
asbestos-containing diaphragms (EC, 2014). Nonetheless,
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environmental risk determinations to scenarios/COUs
that have available actual exposure data.
PUBLIC COMMENTS:
• One commenter explained the duplicate data identified
by the SACC; after removal of those data,
approximately 60% of full-shift samples were below the
LOD.
• The chlor-alkali plant monitoring data might not
adequately represent all chlor-alkali facilities. The
industry might have selected certain data for
submission, and data were not provided for 5 of the 15
plants in the industry.
• One commenter believed that practically none of the
approximately 400 persons identified in Table 2-7 were
exposed above the OSHA PEL (Table 2-4, 2-5 and 2-6;
Draft RE for Asbestos pp. 66-68), which the commenter
considers applicable. Breathing zone samples were
likely even lower.
• EPA could have investigated whether the chlor-alkali
industry monitoring data addressed all high-exposure
activities by using a checklist developed by the industry
itself (e.g, the Chlorine Institute's Pamphlet 137).
• The Draft RE for Asbestos does not include all relevant
studies, specifically, Longo et al. (2002) found high
airborne exposures to asbestos during gasket removal,
including some that were substantially higher than
OSHA's PELs.
• Some commenters presented arguments as to why
importation, handling, storage, and conversion of
chrysolite asbestos into diaphragms should not pose an
unreasonable risk, with monitoring data registering
below OSHA PELs.
• Elimination of asbestos, where possible, is the first step
in the hierarchy of controls. Since many chlor-alkali
plants have eliminated asbestos membrane cell
EPA compiled information from EU facilities. This
information came from two EU documents:
In 2014, the European Chemicals Agency published its
Background document to the Opinion on the Annex XV
dossier proposing restrictions on Chrysotile (ECHA, 2014).
Asbestos sampling data are presented for the one facility that
continued to use asbestos-containing diaphragms at the time.
However, no personal exposure monitoring data are
available. The report explains: "For practical reasons (viz.
the type of sample pumps used to sample the required
volume of air) it is not possible to perform personal
monitoring. All measured data are based on stationary
measurement." EPA infers that "stationary measurement"
refers to area sampling.
Section A2.2 of that report discusses occupational exposures
to asbestos for seven specific worker activities involved in
"use in diaphragm cells (closed systems)." Three of these
worker activities involved area sampling, and asbestos
detections were reported in areas where electrolytic cells
were assembled and where parts were dismantled and
cleaned. The highest 90 percent upper confidence limit
concentration reported was 253 fibers/m3, which occurred in
the area where electrolytic cells were assembled. This
concentration is equal to 0.000253 fibers/cc—the
measurement unit used throughout Part 1 of the Risk
Evaluation for Asbestos.
Later in 2014, the Joint Research Center of the European
Commission published its Best Available Techniques (BAT)
Reference Document for the Production of Chlor-alkali.
Table 3-40 of that report summarizes concentrations of
asbestos in workplace air at three chlor-alkali facilities. For
two facilities in Germany (one of which has since shifted to
non-asbestos alternatives), the asbestos concentration in
workplace air is reported as "<1 000" fibers/m3, which
equates to less than 0.001 fibers/cc. For a manufacturing
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technology from the production process, this suggests
that other facilities could do so as well.
• One commenter found use by the chlor-alkali industry
disturbing, with reported high exposure levels, a high
potential for accidental release during the shipment of
asbestos from ports to plants, and the unjustified
assumption that respiratory protection will suffice to
mitigate possible exposures.
• EPA relies on testimonials by ACC's Chlorine
Chemistry Division for information on asbestos
exposure in nine chlor-alkali plants. One synopsis of
best practices implies that all nine plants operate the
same way; that is highly unlikely. A table summarizes
asbestos air monitoring data from 1996-2016 without
the number of samples collected at each plant for each
task, the industrial hygiene procedures and methods
used for the sampling, or the laboratory analytical
methods used.
facility in Poland, which was shut down in 2012, the
asbestos concentration in workplace air prior to shutdown
was reported as "5 000-30 000" fibers/m3, which equates to
0.005 to 0.030 fibers/cc. Further details on the sampling data
are not provided.
Overall, the full-shift central tendency concentration that
EPA used in the Draft RE for Asbestos was 0.0060 fibers/cc.
This number is reasonably consistent with the range of
values reported above, considering the differences in
manufacturing environments and sampling strategies (i.e.,
EPA compiled personal breathing zone data for workers,
whereas the data cited in the EU reports are area samples).
To be responsive to this comment, EPA inserted the
following text in Section 2.3.1.3.4: "EPA also considered
information published by European Union (EU) agencies
(EC, 2014; ECHA, 2014). Those data ultimately did not
factor into this report's exposure estimates due to differences
in sampling strategies, facility processes and production
rates, and U.S. versus EU regulatory frameworks."
EPA used the most recent data from the facilities that
currently handle asbestos.
Comparisons with the past exposures data were not included
in the risk evaluation.
Regarding comment that chlor-alkali workers in the U.S. are
not exposed to asbestos above OSHA's PEL, EPA notes that
evaluation of compliance with OSHA's asbestos standard
and the protectiveness of the asbestos PEL is not the purpose
of the Part 1 of the Risk Evaluation for Asbestos.
Feasibility of eliminating asbestos from chlor-alkali facilities
and other control strategy options will be appropriately
considered in risk management for chrysotile asbestos,
following the issuance of Part 1 of the Risk Evaluation.
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EPA acknowledges that it did seek information from ACC,
but EPA also sought information from the three companies
that currently use asbestos-containing diaphragms in their
processes. The responses from those companies included
facility-specific information. Additionally, EPA conducted
site visits to chlor-alkali facilities, as described in the
Problem Formulation document. Therefore, EPA's
assessment of the chlor-alkali COU reflects the best
information reasonably available to EPA and not just
information provided by ACC.
Regarding data provided for the chlor-alkali plants, EPA
received monitoring data from eleven facilities owned by
Axiall, Occidental, and Olin. Data from the three companies
were used for the estimates which represent all current chlor-
alkali facilities in the US.
2.21 Chlor-alkali occupational non-user (ONU) exposure estimates
SACC1
6,
35,42,
51,70,
72, 73,
77, 83,
86,91,
108
SACC COMMENTS:
• The chlor-alkali exposure point air concentrations used
for the ONU exposure assessment are based on 15
samples (all non-detects) collected at only two facilities
(a small subset of the facilities used for worker exposure
estimation), representativeness was suspect.
• SACC members appreciated the pictures/graphics and
site visit descriptions where provided. Duplicate data
were identified in the chlor-alkali industry data set
[ACC data set] which should be removed from the
analyses. Standardized approaches to addressing values
less than detection limits should be adopted. While
acknowledging data sparsity [especially for
occupational non-users (ONUs)], members wanted to
see descriptions of sampling plans and methods for
available data and a more structured approach to
estimation of exposure point concentrations in the
For the chlor-Alkali ONU exposure estimate in Part 1 of the
Risk Evaluation for Asbestos, EPA made several
assumptions including the assumption that workers not
directly handling asbestos may access the work area and
ONU exposure concentration is comparable to the area
monitoring result. It is possible that workers not related to
chlor-Alkali production may be trained on asbestos so that
they could access the work area for tasks unrelated to chlor-
alkali.
EPA used the study by Mangold et al. (2006) to estimate
"reduction factors" for ONU assessments for sheet gasket
COUs. While the comment correctly points out that the
Mangold et al. (2006) publication may not report magnitude
of asbestos concentrations consistent with the sheet gasket
COUs, EPA did not use the publication for that purpose.
Rather, EPA used the publication's data to estimate the
decay rate of asbestos levels with distance from the area of
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absence of data. Concerns were raised over
completeness and representativeness of industry data
and for inadequate characterization of "off-normal"
events.
PUBLIC COMMENTS:
• ONU exposure assessment is based on fifteen (15) area
samples at fixed locations at two facilities, all of which
were below the LOD -0.004 f/cc in one case and 0.008
f/cc in the other. The samples were taken primarily in
the deposit and cell service areas, both of which have
restricted access. ONUs are unlikely to "pass through or
work near" restricted areas. A downward adjustment
using appropriate fugitive emission modeling is
necessary to estimate ONU exposures.
• EPA's reference to "maintenance and janitorial staff
should also be clarified; they are included the OSHA
workplace standard for asbestos. Restricted areas are
not attended by non-operator janitors. Housekeeping
within a restricted area is performed by operators with
designated minimum PPE for the task.
• The Draft RE for Asbestos presents conflicting
information on the number of ONUs that are present at
chlor-alkali facilities. While Chapter 4 suggests that
there may be 2,000 to 3,000 ONUs at these facilities,
Chapter 2 estimates the number at about 100. Moreover,
even 100 would be an overestimate non-operator ONUs
in or around restricted areas given procedures in place
for restricted area access.
• The Man«old et al. (2006) studv of asbestos exposure
during removal of gaskets relies was generated to assist
a gasket manufacturer subjected to lawsuits. It did not
consider the dustiest activities associated with removal
of old gaskets. EPA selected the midpoint to estimate
ONU exposure and stated that might overstate risk
active work. EPA believes use of the data for relative
insights (as opposed to absolute exposure levels) is
appropriate.
EPA reviewed the approach used for handling non-detect in
Part 1 of the Risk Evaluation for Asbestos and confirmed
that it is consistent with other risk evaluations.
EPA reviewed and included all reasonably available and
pertinent information in Part 1 of the Risk Evaluation.
During the review, EPA did not find any background
information on the chlor-alkali monitoring data, such as
sampling plans and data handling methods. The data EPA
used in Part 1 of the Risk Evaluation came from employers'
worker monitoring, which evidently was conducted in
fulfillment of OSHA's asbestos standard. The OSHA
asbestos standard has worker exposure monitoring
requirements, but that standard does not prescribe
development of sampling plans and data handling methods.
However, EPA did confirm other important details for those
data sets (e.g, sampling methodology used, type of sample
collected, worker activities conducted during the sampling).
The last comment states that ONUs monitoring data were not
available because ONUs are not exposed, and therefore were
not monitored. EPA used area monitoring data (most below
the limit of detection but some above) and a decay factor to
estimate ONU exposures. The information used to develop
the decay factor showed that the asbestos concentration in
workplace air decreases as you move farther away from the
source. This is an indication that none detect measurements
near the source of asbestos do not necessarily mean zero
asbestos in workplace air. For multiple conditions of use,
EPA has information confirming that ONUs are present
during the activity of interest. For instance, EPA observed
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because the simulation study occurred in an enclosed
setting. EPA does not, however, explain that the
estimate may understate risk because the simulation
does not represent actual workplace conditions (e.g,
participant bias.)
• Industrial hygiene data were not available for ONUs
because these workers are not likely to be exposed and
therefore are not subject to monitoring. EPA lacks any
evidence or data that ONU's are exposed to asbestos,
and ND samples do not demonstrate exposure to a
substance. EPA cannot make a finding that this COU
"presents an unreasonable risk of injury to health or the
environment" based on the evidence it presents.
this for sheet gasket stamping, and numerous reports in the
literature confirm bystanders are present during auto repair
work. Just because no personal sampling data are available
for these ONUs does not mean that exposure did not occur.
EPA continues to believe that relying on the available data
sets, even if they were uniformly non-detect in some
circumstances, is the most reasonable approach to
characterize these ONU exposure scenarios.
2.22 Concerns about properties of fibers in air
SACC,
42, 61,
70, 78,
79, 82,
95
SACC COMMENTS:
• Rapid settling implies increased floor load, which is
then available for resuspension; air measurements at
specific locations reflect countervailing processes
(compensating effects). SACC recommended papers
investigating fiber dispersion in indoor and outdoor
environments.
PUBLIC COMMENTS:
• Research showing "that fibers in the vicinity of 5-40
microns in length" is older and outdated from the 1960s
(Hinds (1999; Corn and Stein (1967, 1965). The
assertion that fibers will drift from a point source and
cause a potential hazard to nearby workers or become a
source for resuspension is not often the case, especially
for fibers with a length of 5-40 |im that will
agglomerate and fall due to gravity. Similarly, fibers in
dust are not so easily resuspended.
• EPA does not consider many other factors such as the
overreliance on ventilation and gravitational settling in
EPA continues to believe that ONU exposures are
reasonably foreseen for certain COUs. However, EPA
understands that the entire premise of ONU assessments
presume that fibers from a worksite can move through the air
to other workplace locations, and that EPA did not explicitly
state in the Draft RE for Asbestos that asbestos fibers will
move long distances—or that previously settled fibers
become resuspended into the air. EPA reviewed multiple
studies that report data (both measured and modeled) on how
asbestos concentrations decay with distance, and none of
these publications suggested instantaneous deposition of all
airborne fibers. Thus, EPA believes it is plausible that fibers
can move through the air.
It should be noted that EPA reconsidered ONU analyses for
all COUs and made changes in response to comments. EPA
used a different data source for the ONU estimates for the
aftermarket automotive brakes/linings COU as described in
Section 2.3.1.7.5.
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models, proper ventilation systems, inert properties of
most lengths, and other recent research. One commenter
pointed out there is "no support that particles from
brake repair, gasket replacement, and other processes
will emit particles that would remain suspended in air or
be resuspended." The half-life for these fibers to settle
out is on the order of 5 minutes not hours or days. These
commenters urge EPA to revisit the physical settling
properties of asbestos fibers.
• The EPA assertion of resuspension of asbestos fibers as
a plausible and significant contributor for ONU
exposure is unfounded.
2.23 Age at first exposure and exposure duration
70, 72,
100
SACC COMMENTS:
• One SACC member felt that a starting age of 16 years
is too young for tasks typically assigned to experienced
workers.
PUBLIC COMMENTS:
• The Draft RE for Asbestos assumption that
employment begins at 16 contradicts chemical industry
practice which requires persons to be at least 18 years
old to work in chemical facilities. EPA's assumption
that worker exposure continues for 40 years is also
inconsistent with current industry employment data and
with Agency assumptions for other programs. The
average tenure of workers who handle asbestos is less
than 20 years; it is very common for a worker to begin
in one production unit and move to another unit where
asbestos is not used.
• Based on the available information, a more appropriate
assumption for the central tendency of exposure
duration for the evaluation is in the range of 5 to 10
years (not 40 years), while a more appropriate
There is no evidence supporting that tasks related to handling
asbestos require skills and experience. Thus, EPA has not
revised the age at first exposure and exposure duration for
most analyses conducted for Part 1 of the Risk Evaluation
for Asbestos focused on chrysotile asbestos. However, EPA
did revise analyses for the COU related to the specialize
large NASA transport plan (Super Guppy) to begin at 16
years of age. The draft risk evaluation presented analyses
beginning at age 26, but EPA did not find specific
information that supported the assumption of a certain level
of training and experience for these workers.
The occupational exposure assessment made standard
assumptions of 240 days per year, 8 hours per day over 40
years starting at age 16 years. EPA notes that the Fair Labor
Standards Act of 1938 allows adolescents to work an
unrestricted number of hours at age 16 years.
EPA retained assumptions made in the risk estimates as
Bureau of Labor Statistics data provides statistics for
workers beginning at age 16 (for example, see Table 2-32 in
Part 1). Furthermore, EPA's approach to cancer risk
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assumption for high-end exposure duration is 25 years.
This is consistent with other EPA risk assessment
guidance (e.g, EPA Regional Screening Levels)
• Second, workers in chlorine production facilities
handle friable asbestos on an intermittent basis. The
total time spent handling dry asbestos is estimated to be
about 76 hours per week (1.6 hours/week per
employee). The balance of their time is spent doing
other tasks unrelated to handling asbestos, such as
warehousing activities, training, and other activities.
• To calculate an 8-hour TWA exposure, EPA assumed
that brake job-specific exposure occurs throughout the
day over a 40-year working lifetime. That is unlikely to
be a common occurrence, especially for brakes
containing asbestos.
• EPA's assumption that a worker is exposed for 40
years for both its central tendency and high end
scenarios is far longer than the information available
from the Bureau of Labor Statistics, which indicates
median employment tenure for workers in the chemical
industry is 10 years or less, taking into account all age
groups.
• Data from the Employee Benefit Research Institute or
EBRI show that the median tenure with one employer
of all wage and salary workers ages 25 or older has
remained steady at approximately five years. EBRI data
also show that approximately 80% of older workers
(ages 55-64) have tenures at one employer of less than
25 years, and the current trend is consistently toward
lower tenures. As such, 25 years, not 40 years, is a
conservative estimate for high end exposure duration
and should be used for the chlor-alkali scenario.
estimates is based on a 40-year exposure period. EPA does
present partial lifetime estimates in Appendix K of the risk
evaluation Part 1.
For chlor-alkali worker exposure, EPA used the workplace
air measurements to estimate the exposure. For the full shift
measurements, workers wore sampling devices throughout
the entire shift which included time spent away from
asbestos handling activities. Therefore, EPA's assessment
approach for Chlor-Alkali is appropriate and takes into
account the time workers spent for activities unrelated to
asbestos.
For chlor-alkali worker exposure, EPA used the workplace
air measurements to estimate the exposure. For the full shift
measurements, workers wore sampling devices throughout
the entire shift which included time spent away from
asbestos handling activities. Therefore, EPA's assessment
approach for chlor-alkali is appropriate and takes into
account the time workers spent for activities unrelated to
asbestos.
2.24 Approach for considering non-detect values
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SACC,
42, 91,
100
SACC COMMENTS:
• A sensitivity analysis using alternate non-zero values
forND could allay concerns. Statistical methods for
better handling of non-detects are available (2005).
Recommendation 19: Create and consistently utilize an
SOP for processing data with high levels of non-detect.
PUBLIC COMMENTS:
• When a significant fraction of the sampling data is
"ND" (non-detects, i.e., censored data), it is not
appropriate to simply substitute V2 the LOD or the LOD
divided by the square root of 2 to summarize exposure
concentrations. It is even less appropriate to assume the
full LOD for those samples, and for the chlor-alkali
industry, 60% of the 15 samples were ND. By EPA's
approach, absolutely any activity can be determined to
present an unreasonable risk because, at best, such
activities will return non-detect values if sampled for
the presence of asbestos.
• Further, in the "All Data" worksheet, it appears EPA
also included the full value of the LOD as the proxy
non-detect values for the Axiall-Westlake results even
though EPA assigned a value of LOD divided by 2 or
square root of 2 to non-detect data in the Axiall-
Westlake worksheets. This inadvertent mistake should
also be corrected.
EPA notes that while developing the Draft RE for Asbestos,
the ACC provided exposure monitoring data that included
some overlap with the data provided by Occidental, but it
also appeared to include other observations. EPA included
both data sets in the assessment of chlor-alkali worker
exposures and acknowledged the overlap. ACC clarified in a
public comment that its entire data set should be viewed as a
duplicate of industry submissions and removed from the
analysis. Removing these data results in more than half of
the observations being non-detects. EPA has updated its
chlor-alkali data analyses to reflect this change: refer to
Section 2.3.1.3.4 for changes that EPA made when
addressing this comment.
EPA's approach for non-detects is documented in an EPA
report. Guidelines for Statistical Analvsis of Occupational
Exposure Data, which calls for replacing non-detects with
either one-half the detection limit or the detection limit
divided by the square root of two, with the preferred
approach depending on the skewness of the data distribution
(as characterized by the distribution's geometric standard
deviation). EPA followed this guidance when processing the
chlor-alkali data. After removing the ACC data from the
evaluation (see previous bulleted item), more than half the
sampling results are non-detect observations. In these
situations, the same reference recommends acknowledging
potential biases introduced into calculations. Following this
guidance, EPA has added text in Section 2.3.1.3.6 to
acknowledge uncertainties.
EPA conducted a sensitivity analysis for various non-detect
replacement strategies and included text in Section 2.3.1.3.6
that discusses the range of central tendency concentrations
based on the sensitivity analysis.
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EPA acknowledges an inadvertent error in incorrectly using
the full detection limit when processing the "Axiall-
Westlake" data in the Draft RE for Asbestos. EPA corrected
this analysis, which had minimal impact on the final asbestos
concentrations for the chlor-alkali data set in Part 1 of the
Risk Evaluation for Asbestos.
EPA has made these additional changes to Part 1 of the Risk
Evaluation for Asbestos:
• EPA removed the ACC data from its evaluation and
recalculated exposure concentrations for the chlor-alkali
COU. All tables and text citing these concentrations were
updated accordingly. New text was added to Section
2.3.1.3.4 describing removal of the ACC duplicated data.
• EPA added text to S ecti on 2.3.1.3.6 to acknowl edge
uncertainties associated with the dataset, given that more
than half of the measurements were non-detect
observations. This discussion also addresses the
sensitivity associated with different non-detect
replacement strategies.
2.25 Sheet gasket stamping worker exposure estimates
SACC,
42, 46,
61,83,
95, 98
SACC COMMENTS:
• For the sheet gasket COU, the Draft RE for Asbestos
uses data from a simulation (Mangold et al. (2006) that
was not conducted in a factory setting and involved
automobile gasket removal rather than a sheet gasket
making process. One SACC member concluded that the
Draft RE for Asbestos underutilizes available data by
EPA clarifies that it did not use Mangold et al. (2006) to
derive sheet gasket exposure data. The Draft RE for
Asbestos based worker exposure estimates on occupational
exposure monitoring conducted at the facilities that
fabricated gaskets and that used these gaskets. The only
inference EPA drew from the Mangold et al. (2006) study
was the rate at which asbestos concentrations decay between
exposed workers and ONUs. EPA continues to believe this is
an appropriate interpretation of the Mangold et al. (2006)
study.
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selecting only this study on which to establish exposure
levels to this COU.
• Recommendation 23: Collect and provide sampling
plans and handling methods for data used to establish
COU exposures when possible.
PUBLIC COMMENTS:
• EPA received data from one company that fabricates
sheet gaskets and one company that uses sheet gaskets
and admitted that the data are unlikely to be
representative of practices in their respective industries
(Draft RE for Asbestos p. 195, In. 6904-906). EPA
identified one firm that punches out gaskets that contain
chrysotile; the commenter does not know of any other
firms that punch gaskets with asbestos-containing
materials in 2020.
• The data presented for the facilities indicate exposures
of two to four workers, who might work the press
occasionally. The commenter later states that one
facility employs four workers. The information
presented by EPA about the number of persons who
"might" work with asbestos-containing gaskets in the
coming years is not accurate.
• The COU seems unnecessary to evaluate, given the few
numbers of persons exposed, the low levels of airborne
asbestos concentrations measured in these facilities, and
the lack of potential future exposures to asbestos.
• Sheet gaskets contain up to 50% of resin-soaked
asbestos, and these fibers are embedded in a resin or
other polymeric material. They are not released to a
measurable degree during routine cutting procedures.
• There are no more than 0.001% of all new gaskets
might contain asbestos and virtually no old gaskets
being replaced today (they should have been replaced
20-30 years ago).
EPA addressed the compilation of sampling plans for data
used to establish COU exposures in the first part of the
response to comment category 2.18.
EPA confirms that it relied on occupational exposure data
from a small number of companies that fabricate and use
asbestos-containing sheet gaskets. EPA believes this reflects
the fact that only a small number of companies engage in
these activities. This is not considered a limitation in the
occupational exposure assessment.
EPA staff personally observed sheet gasket stamping
operations during site visits. Based on those observations and
input from the one company known to manufacture these
gaskets, EPA believes its estimated number of exposed
workers accurately reflects current conditions. Commenters
do not expand further on what a revised or alternate number
should be.
EPA believes that any relevant COU is necessary to consider
in the risk evaluation, regardless of number of workers
exposed. EPA evaluates circumstances ".. .under which a
chemical substance is intended, known, or reasonably
foreseen to be manufactured, processed, distributed in
commerce, used, or disposed of." There is no minimum
threshold of workers below which EPA automatically
disregards potential exposures and risks.
The best information reasonably available to address release
of asbestos during sheet gasket stamping is the exposure data
collected at the facility that fabricates these gaskets, and
those data showed PCM-detected asbestos in worker
breathing zone samples. Therefore, EPA has not revised Part
1 of the Risk Evaluation for Asbestos in sections pertaining
to sheet gasket stamping and related exposures. EPA does
acknowledge that a relatively small portion of sheet gaskets
currently in use contain asbestos, but inclusion of this COU
is still warranted.
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• See original comment for screenshot displaying gasket
exposure measurements from specific activities related
to cutting, installation, and removal.
• The high-end values in Table 2-11 are not consistent
with the published literature or the experiences of most
of the industrial hygienists in the field for an 8-hour
TWA (even 20-30 years ago) due to the infrequency of
the worker's contact with these materials.
• The exposure assessment studies that EPA used in the
Draft RE for Asbestos to quantify worker asbestos
exposures as a result of sheet gasket removal and oil
field brake block work are missing information (e.g,
sampling duration and locations, analytic method,
number of samples, description of work) that is both
fundamental and necessary for assessing asbestos
exposures resulting from this work.
EPA explained in the text how exposure estimates were
derived for high-end exposure concentration. The magnitude
of the concentration (0.059 fibers/cc) was measured during a
30-minute sample at the one company known to manufacture
asbestos-containing sheet gaskets. EPA noted in the text that
the high-end 8-hour TWA was estimated under the
assumption that the activity that occurred during that sample
could reasonably be foreseen to occur throughout a full work
shift. EPA believes this is an appropriate assumption for
reasonably foreseeable worst-case conditions.
A comment also notes that sheet gasket removal and oil field
brake block measurements are missing some study details.
EPA acknowledges the missing details (such as analytical
methods and monitored duration.) Nevertheless, EPA
believes that these are the most relevant measurements for
the report and rationale for the selection is included.
2.26 Sheet gasket stamping and use ONU exposure estimates
42, 61,
65, 83
PUBLIC COMMENTS:
• EPA's general approach to estimating exposures of
bvstanders is reasonable. A oaoer bv Donovan et al.
(2011) specifically evaluates bvstander exposures when
working with asbestos-containing materials. That paper
and the two letters to the editor regarding that paper are
the best available information for estimating these
bystander exposures.
• EPA did not identify any ONU exposure measurements
for sheet gasket stamping and overestimated exposure
for this. Mansold et al. (2006) measured "bvstander"
exposure during asbestos-containing gasket removal;
however, EPA assumes the ONU is present in the area
EPA has not revised the "reduction factor" used in Part 1 of
the Risk Evaluation for Asbestos but has noted the
consistency between the employed approach and that in
Donovan et al. (2011) (see Section 2.3.1.4.5). EPA derived a
"reduction factor" that estimated asbestos concentrations will
decrease by a factor of 5.75 between the worker and an
ONU, located up to 10 feet away. EPA's estimate is on the
same order of magnitude of the Donovan et al. (2011)
estimates. That publication indicated a "reduction factor" of
2.85 for workers 5 to 10 feet away from the worksite and a
factor of 10 for workers 10 to 30 feet away. The value EPA
used is marginally lower than the midpoint of these two
"reduction factors."
EPA does not believe that the "reduction factor" for the sheet
gasket stamping was overestimated in Part 1 of the Risk
Evaluation for Asbestos. Some commenters believe that the
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(5-10 feet) for a full 8-hour shift in the risk
characterization.
• Exposures are estimated for workers stamping sheet
gaskets and for ONUs using an averaging of short-term
exposures (assuming 30 minutes) and full shift
exposures (7.5 hours per day of the full shift TWA
exposure) based on monitoring data. With high-end
exposures that approximate V2 the OSHA PEL, how can
risk be unacceptable given the few occasions of possible
exposure per year?
• EPA overestimated exposure for sheet gasket stamping
based on its assumption that the ONU exposures were
the same for all ONU types and that exposure
concentrations based on a factor of 5.75 were
representative of all ONUs. Exposures are likely to be
lower for many of these ONUs based on (a) the larger
distance from asbestos work areas and (b) certain
workers (e.g, office workers) who may have no asbestos
exposures when away from the asbestos work area.
• Commenter has investigated the issue of friction
products as manipulated during brake maintenance and
repair. They also studied service on vehicles and the
nature of brake dust, its composition and character as it
relates to its biological potential. Their data and
conclusions do not support the position put forward by
EPA. Gasket studies show the action of gasket change
on flanges is associated with exposures that are
extremely low. Considering all the factors of gasket
change by steam-fitters their risk is barely measurable.
• EPA correctly states that the replacement of these
gaskets occurs mostly during plant shutdowns and
regular workers are not exposed. It is appropriate for
EPA to assume at least a 5-fold decrease in exposures
for the occasional ONU who might be passing by during
the removal/installation operations. Most of the
industrial operations are carried out outdoors and
Donovan et al. (2011) is the "best available information", but
EPA notes that nearly the same reduction factor would have
been calculated had the agency based it on that study. EPA
believes it is appropriate, for sheet gasket stamping, to
assume the ONUs are present in the same work environment
throughout their shifts. During a site visit, EPA observed
other workers who do not work with asbestos-containing
sheet gaskets in the same open manufacturing space; and
these other workers appeared to work in this room for their
entire shift (except for breaks, lunch, etc.).
EPA does not aim to evaluate compliance with OSHA's
asbestos standard and the protectiveness of the asbestos PEL
in Part 1 of the Risk Evaluation for Asbestos.
EPA has added text in Section 2.3.1.4.3 of Part 1 of the Risk
Evaluation for Asbestos to clarify which workers are
considered ONUs for the sheet gasket fabrication condition
of use. Specifically, the Branham facilities had asbestos-
containing sheet gasket activity occur in a warehouse-like
space, where other workers (ONU) spent their entire shift
doing other tasks. Those other workers were considered
ONUs for this condition of use, because they might have
been exposed to asbestos fibers released from the stamping
operation.
On the other hand, Branham facilities had office workers
who spend their days in enclosed rooms separate from where
the sheet gasket stamping occurred. These office workers
were not considered ONUs, because they likely are not
exposed to asbestos that might be generated during stamping
operations.
EPA opted to use the data provided by the one company
known to engage in use and removal of asbestos-containing
sheet gaskets. These data suggest that asbestos is detected by
PCM in the air during this activity, and EPA continues to
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personnel can avoid passing by regulated areas. ONUs
are likely to have sporadic, if any contact with this
material in such environments.
believe these measurements are most representative of
current uses.
2.27 Limited scope of industries relevant to sheet gasket stamping
42,51,
65, 85
PUBLIC COMMENTS:
• The Draft RE for Asbestos indicates that only a limited
number of asbestos-containing sheet gaskets rolls are
imported each year for one specific use in one industry.
That is why they can be produced by one firm on a
handful of days per year (involving just two
employees). Thus, exposures are insignificant relative to
other Agency concerns.
• If a pipefitter replaces gaskets older than 30 years, the
worker should assume that asbestos might be in the
gaskets and use current OSHA practices to limit
exposure. Such exposures are generally less than the
OSHA PEL and are immeasurable small when the work
is conducted outdoors.
• EPA acknowledged that other companies might process
and use asbestos sheet gaskets, but it had no knowledge
of how many. EPA, therefore, lacks information about
respirator use beyond the two companies it contacted
and has no basis to assume that workers uniformly wear
respirators across this COU.
• When describing use of sheet gaskets, EPA only
considers the use in inorganic manufacturing. The
application is much broader and includes chemical and
refining industries.
EPA evaluates circumstances ".. .under which a chemical
substance is intended, known, or reasonably foreseen to be
manufactured, processed, distributed in commerce, used, or
disposed of." There is no minimum threshold of workers
below which EPA automatically disregards potential
exposures and risks. Thus, inclusion of sheet gasket
fabricators is warranted.
EPA acknowledges that certain workers who remove sheet
gaskets must comply with requirements in the OSHA
asbestos standard. EPA opted to use the occupational
exposure data provided by the one company known to use
these asbestos-containing sheet gaskets, and the Agency
continues to believe that is the best approach for evaluating
this COU. Regarding comparisons to the OSHA PEL,
evaluation of compliance with OSHA's asbestos standard
and the protectiveness of the asbestos PEL is not the purpose
of the risk evaluation.
EPA notes in Part 1 of the Risk Evaluation for Asbestos that
it was only aware of one company that fabricated these
gaskets and another company that used them. All
observations presented in Part 1 are based on what occurs at
those two companies. EPA continues to believe that it is
appropriate to base risks on what is known about respirator
use for these companies.
EPA acknowledges that sheet gaskets may be used in
applications beyond use in titanium dioxide manufacturing,
but the Agency could not confirm any additional uses.
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2.28 Availability of quantitative data, study quality, or external validity for sheet gasket stamping
38, 42,
51,63,
73, 85,
92
PUBLIC COMMENTS:
• The gasket replacement air sampling data from
Chemours are missing critical information (e.g,
sampling duration, frequency, analytic method, indoor-
vs-outdoor, ventilation, number of samples below the
LOD, etc.) needed to use the data in an exposure
assessment. EPA only assumed the data represented
short-term samples. Although not known, it is likely
that the samples were collected for either 30 minutes or
8 hours as part of OSHA compliance monitoring and
that asbestos concentrations were lower than their
respective PELs.
• The limited monitoring data from a single processor of
asbestos-containing sheet material might not be
representative of workers in the COU. The Draft RE for
Asbestos states that the facility had only one worker
who processed asbestos-containing gaskets (p. 74). That
worker is perhaps the only person in the US in this
COU.
• The gaskets are not new in design; EPA should more
fullv explore the literature 1e.s, see two studies Boelter
et al. (2011; Boelter et al. (2002) that EPA rated as hi eh
quality which provide probative exposure data on
removal of old gaskets and cleaning the sealing surface
prior to installation of a new gasket.]
• EPA apparently did not review data from the 22 states
and territories that operate their own OSHA-approved
analytical laboratories and maintain their own exposure
monitoring data from inspections of workplaces.
• Other data are available in the international literature
(e.g, from the Netherlands, study of workers who
EPA believes the assumptions made when interpreting the
data err on the side of precaution (i.e., assuming the data are
8-hour TWA concentrations as opposed to 30-minute TWA
concentrations), which the Agency feels is an appropriate
approach when further details on the sampling are not
available. EPA agrees that the sampling data likely were
collected as part of OSHA compliance monitoring. The data
were provided by ACC, which submitted multiple public
comments—but did not clarify the issues surrounding
sampling.
EPA does not believe that having data from one facility is a
major limitation for the sheet gasket (stamping) COU, and
that is because only two facilities (both owned by the same
company) account for all known asbestos-containing sheet
gasket stamping operations nationwide.
EPA reviewed all publications cited in the peer review
comments and public comments for further information on
worker exposure to asbestos during sheet gasket removal.
That literature addresses a broad range of industrial settings.
EPA did not find compelling evidence from the literature for
changing the exposure estimates for the sheet gasket
fabrication condition of use. The two publications cited in
this comment (Boelter et al., 2002, 2011) reported asbestos
exposures nearly identical to those used in the risk
evaluation.
EPA has revised Section 2.3.1.5.4 to indicate that the
Agency views it most appropriate to base risk evaluation on
observations at the one company known to use the asbestos-
containing sheet gaskets
When preparing this Risk Evaluation, EPA obtained and
considered reasonably available information, defined as
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removed braided gaskets and sheet gaskets; Spence and
Rocchi (1996).
With data from one manufacturing plant, EPA has no
basis to assume "the absence of asbestos exposure" for
this COU.
The study on which EPA relied used an inadequate
sampling volume.
Some gaskets stick to sealing surfaces very tightly and
require hand or power wire brushing to completely
remove, resulting in exposure levels much higher than
the high-end values summarized in Table 2-11 of the
Draft RE for Asbestos.
information that EPA possesses, or can reasonably obtain
and synthesize for use in Risk Evaluations, considering the
deadlines for completing the evaluation. Federal OSHA
implements worker safety and health programs in many
states throughout the country, but a few dozen states have
their own OSHA programs - and these are called "state plan
states. EPA reviewed data provided by OSHA and
incorporated the information in the risk evaluation. However,
the OSHA data EPA reviewed does not indicate if "state plan
states" information is included. It is possible that the current
OSHA data system is separate from the state's because it
requires considerable effort to integrate the information.
EPA acknowledges the limitation in not reviewing
occupational exposure data collected by OSHA state plan
states. EPA revised Section 2.3.1.1 to reflect this limitation.
EPA clarifies that the Spence and Rocchi (1996) study on
braided gasket removal was considered as described Section
2.3.1.5.4 of Part 1 of the Risk Evaluation for Asbestos.
EPA clarifies that it never assumed the "absence of
exposure," from the sheet gasket COU. The data tables in
Part 1 of the Risk Evaluation correctly identify the estimated
exposures for workers and ONUs at sheet gasket fabricators.
In EPA's judgment, the primary exposures for sheet gasket
fabricators occur during the stamping operation and not
during disposal.
A comment refers to "inadequate sampling volume" for the
sheet gasket stamping exposure data. OSHA's asbestos
sampling method reports "recommended air volumes"
between 25 liters and 2,400 liters per sample; and the method
suggests a minimum sample volume of 48 liters for
assessment of excursion limits (30-minute averages). The
personal breathing zone samples for the sheet gasket
condition of use were collected at a rate of 2.04 liters/minute.
The shortest duration sample was 27 minutes, which would
suggest that all samples collected at least 55.08 liters of air.
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Because this value falls within the recommended range for
OSHA's method, EPA does not consider this to be an
"inadequate sampling volume" and will continue to use these
data to evaluate the sheet gasket fabricator condition of use.
Note also that none of the samples from the sheet gasket
stamping report were non-detect for asbestos, which is not
consistent with "inadequate sampling volume," as the
comment suggests.
EPA continues to believe that using data provided by the one
company known to currently use the asbestos-containing
sheet gaskets is appropriate.
2.29 Assumption that for any specific COU, the ONU exposures were the same for all ONU types
51,
65,83
PUBLIC COMMENTS:
• While the concentration term may be represented by an
8-hour TWA sample, the actual time an ONU may enter
areas near asbestos work zones (5-10 feet) is unlikely to
be 8 hours per day, 5 days per week, for 40 years. Using
those assumptions, EPA has overestimated exposure for
ONUs in potentially every exposure scenario and should
revisit whether it is appropriate to assume that ONUs
(e.g, supervisors, managers, maintenance, janitorial, and
other workers) access asbestos area work zones at the
same intensity/frequency/duration as asbestos workers.
• Because ONUs include "supervisors/managers, and
maintenance and janitorial workers who might access
the work area" (Draft RE for Asbestos p. 56), it is
implausible that these ONUs spend 8 hours a day, 240
days/year, for 40 years within 5 feet of a mechanic
using imported brakes.
• A time weighting factor (TWF) was applied for DIY
consumers and bystanders, and this recognition of the
importance of exposure duration should also be
examined in the context of ONUs.
EPA agrees that ONU may not be exposed for entire full
shift, every workday.
ONU exposure is likely to vary depending on COU, sites,
and what tasks are assigned to ONUs. EPA does not have
information to further refine ONU exposures for each COU.
EPA searched for the exposure data and was able to find
only one source which was used in the risk evaluation. EPA
made several attempts to reach out to the industry and public
for additional information but was unsuccessful.
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2.30 Oilfield brake blocks worker exposure estimates
SACC,
38, 42,
51,65,
83
SACC COMMENTS:
• For the oil field brake blocks COU, worker exposure
data are sparse, but were at least collected on an oil rig
during brake block replacement. Further description of
how brake blocks were replaced and how many
individuals were in the immediate area would be
helpful. While the replacement activity might generate
the most likely exposure, individuals who work around
the machine when it is operating might also be exposed
because of brake block wear. SACC questioned why the
Draft RE for Asbestos used the lower of two reported
worker air values rather than using a central tendency
(mean, median) estimate.
PUBLIC COMMENTS:
• As noted by SACC, the oil field brake block exposure
data is missing some critical information (e.g, sample
duration and frequency, analytic method, number of
samples, area versus BZS, description of the work tasks
and equipment used, ventilation, PPE.)
• While it "is reasonable to assume that wear of the brake
blocks over time will release some asbestos fibers to the
workplace air," the "magnitude of these releases and
resulting worker exposure levels is not known."
• Chens and McDermott (1991) calculated occupational
TWA exposures lower than those in the Draft RE for
Asbestos. Apparently, EPA assumed that the time not
sampled (the unaccounted time) has the same exposure
intensity as the time that was sampled (measured),
resulting in overly conservative estimates.
• Table 2-12 gives the impression that 17,831 firms, with
a total employment of about 530,000 people, could be
EPA considered exposures to workers in the vicinity of the
brake replacement activity in the ONU evaluation. EPA
updated the language in Section 2.3.1.6.2 and 2.3.1.6.5 of
Part 1 of the Risk Evaluation to be clearer. Concentrations
from Steinsvag et al. (2007) that were included in Part 1 are
those for the worker exposure estimate and the ONU
exposure estimate. EPA has clarified this point in Section
2.3.1.6 as well. EPA selected the higher of the two reported
worker values for the worker exposure estimate. The lower
value was selected only for the ONUs. EPA continues to
support this approach, as ONUs near the main worksite will
likely have lower exposures, when compared to the directly
exposed workers.
EPA was not able to document the full range of sampling
details for the oil field brake block COU because Steinsvag
et al. (2007) did not include sufficient documentation of
details.
EPA reviewed Cheng and McDermott (1992) for Part lof the
Risk Evaluation for Asbestos exposure estimates for the
sheet gasket COUs; however, EPA does not find this study to
have any bearing on consideration of oil field brake blocks.
EPA adequately described information demonstrating
asbestos-containing oil field brake blocks in the U.S. EPA
spoke directly with the representative of a company that
continues to purchase and sell asbestos-containing oil field
brake blocks in the U.S., and EPA has added language to
acknowledge uncertainties about the amounts of asbestos-
containing brake blocks in use.
With regard to the estimated number of workers potentially
exposed for the oil field brake block COU, EPA
acknowledges that these are the high-end estimates based on
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exposed to asbestos from these oilfield brake blocks,
which is not possible.
• Steinsvas et al. (2007) stated that the "samples were
analyzed by stationary samples of asbestos fibers on the
drilling floor at one installation in 1988." Because there
is no need for a worker to be near the brakes, at most
those samples might represent a short-term peak
exposure for a person who happened to be there,
probably for no more than an hour per month. The data
are not representative for the COU and would
overestimate exposure. One commenter recommended
dropping the exposure scenario (or altering Draft RE for
Asbestos Table 2-13).
• In consideration of the measured 0.02-0.03 fibers/cc,
assuming one hour of exposure on any particular day,
the 8-hour TWA would be approximately 0.003
fibers/cc. Furthermore, assuming one day a month of
such exposure, a 45-year career cumulative exposure
would be 0.006 fiber/cc-year.
• One commenter was adamant that there is no evidence
that the brakes in these rigs have contained asbestos
over the past 35 years. The MSDS cited by EPA is 8 to
10 years out of date; the commenter suggested that EPA
confirm that chrysotile in oilfield brake blocks
applications continues to exist.
• EPA identified one company that "imports asbestos-
containing brake blocks on behalf of some clients for
use in the oilfield industry," but it is not known if other
companies fabricate or import asbestos-containing brake
blocks or how widespread continued use of asbestos
brake blocks in oilfield equipment might be (Draft RE
for Asbestos p. 83, In. 3007-3010). This uncertain
statement does not constitute a plausible exposure
scenario.
the reasonably available information. Part 1 of the Risk
Evaluation for Asbestos describes key assumptions and
uncertainties pertaining to exposure estimates for each COU.
EPA acknowledged limitations of data from Steinsvag et al.
(1998) included in Part 1 of the Risk Evaluation for Asbestos
and assigned these exposure estimates the lowest confidence
rating. EPA continues to think this is the best approach for
this COU and has revised Section 2.3.1.6.6 to further
emphasize the uncertainties associated with the exposure
estimates for this COU.
EPA acknowledges that there is limited information
available on chrysotile asbestos for the oil field brake block
COU but does not agree that "there is no evidence that the
brakes in these rigs have contained asbestos over the past 35
years," as one comment suggests. As noted above, the two
main lines of evidence EPA considered to identify this COU
are a Safety Data Sheet documenting the presence of
asbestos and written and verbal input from a representative
of a company that continues to purchase and sell asbestos-
containing oil field brake blocks in the US.
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2.31 Oilfield brake blocks ONU exposure estimates
SACC,
42,51,
65, 77,
98
PUBLIC COMMENTS:
• Rigs are outdoors, which means that there is nearly
infinite dilution in air, so an ONU would have no
measurable exposure to brake wear debris. The
"holding" brake portion of these brakes would release
debris at even the low rate of automobile brakes, and
they are washed down prior to being replaced. This
COU probably should not be in the document.
• Crane brakes are an excellent example of holding
brakes. One studv, Spencer et al. (1999), in the
industrial hygiene peer-reviewed literature found "There
were no asbestos fibers detected by the TEM method
from air samples collected during the operation of the
cranes." In fact. Spencer et al. (1999) found no TEM-
detected asbestos fibers in air samples collected during
the operation of stationary cranes with brakes, even
though crane operators sat within 2 feet of the exposed
brake.
• The COU of oilfield brake relied heavily upon a
Norwegian study which is of limited relevance to the
US oil industry. The commenter provided detailed
information indicating that EPA has overestimated risk
to both workers and ONUs.
• Normal activities of workers operating the break handle
to control the speed of the drawworks could be
considered ONUs, because their exposures are expected
to be incidental and no PPE would be required. These
workers would be at least 5 feet away from the brake
block, and they are not expected to replace the blocks.
EPA included the oil field brake block COU in the Scope
document based on the known presence of asbestos in some
oil field brake blocks distributed in the U.S. and does not
agree that there is "no measurable exposure" for ONUs.
Therefore, EPA retain this COU in Part 1 of the Risk
Evaluation for Asbestos.
EPA reviewed the suggested study on crane brakes when
developing the Draft RE for Asbestos. EPA selected the one
identified study of oil field brake blocks for evaluating
exposure for this COU. Recognizing that crane brakes may
be similar in certain regards, EPA has added text to the
uncertainty section for oil field brake blocks (Section
2.3.1.6.6) acknowledging that the exposure concentrations
used in the risk evaluation may be conservative estimates of
actual exposures, based on the study cited in this comment.
However, EPA does not feel this one study of a similar—but
different—process confirms no exposures among oil field
brake block workers.
EPA has classified its confidence in exposure estimates as
"low," and as noted, and will add language in Section
2.3.1.6.6 of Part 1 of the Risk Evaluation for Asbestos to
acknowledge the possibility of overestimated exposures.
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2.32 Study quality (e.g, use of monitoring data from oil rig drilling floors)
42, 65
PUBLIC COMMENTS:
• EPA identified a single US facility that imports
asbestos-containins brake blocks (Popik (2018). The
number of customers receiving those brake blocks is
unknown, as is the number of potentially exposed
workers. Rather than "guess" the number of AC brake
blocks still in use, EPA should conduct interviews of
the appropriate persons.
• Currently, most braking on AC rigs is electromagnetic.
The disk brakes and friction pads on AC rigs are used as
"parking" brakes and wouldn't experience wear unless
they were not adjusted properly. Modern SCR rigs
would use a Wichita or Eden braking system which
does not use friction pads for normal operation; they
would likely be equipped with disks and friction pads
like the AC rigs. Older SCR rigs would have run drums
with asbestos friction pads. Although, generally
industry had poor experience with non-asbestos pads
glazing over due to high temperatures, so they weren't
preferred.
EPA believes asbestos-containing oil field brake blocks
continue to be imported, distributed and used for older oil
rigs based on consultations with industry representatives
with knowledge of the oil field drilling industry. EPA used
2016 Occupational Employment Statistics data from the
Bureau of Labor Statistics (BLS) and 2015 data from the
U.S. Census' Statistics of U.S. Businesses. EPA used BLS
and Census data for three NAICS codes: 211111, Crude
Petroleum and Natural Gas Extraction; 213111, Drilling Oil
and Gas Wells; and 213112, Support Activities for Oil and
Gas Operations. Table 2-13 in Part 1 of the Risk Evaluation
for Asbestos summarizes the total establishments, potentially
exposed workers, and ONUs in these industries. EPA does
not have an estimate of the number of establishments in
these industries that use asbestos-containing brake blocks.
Therefore, EPA presents these results as bounding estimates
of the number of establishments and potentially exposed
workers and ONUs
EPA has updated the process description text in Section
2.3.1.6.1 to include some of the details raised regarding
braking technologies currently used in the oil and gas
industry. But, even though part of the industry uses braking
technologies that do not involve asbestos, the information
available to EPA suggests that a portion of the industry
continues to use asbestos-containing brake blocks.
2.33 Aftermarket automotive brakes worker exposure estimates
SACC,
32, 40,
42, 61,
77, 79,
80, 90,
95
SACC COMMENTS:
• For the aftermarket brake replacement scenario, SACC
identified a set of papers not used by the Draft RE for
Asbestos based on work in brake shops in Columbia,
where asbestos brake pads are currently legally
marketed (Celv-Garcia et al. (2016b; Celv-Garcia et al.
EPA intentionally limited its evaluation of studies on
aftermarket automotive products to those that examined
exposures in the U.S. because OSHA's asbestos standard
includes provisions that apply to U.S. workers and
worksites—and these provisions do not apply in other
countries. Additionally, the profile of brakes and clutches
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(2016a; Salazar et al. (2015; Cely-Garcia et al. (2012).
Additional domestic literature was identified that did
not appear to have been cited in the Draft RE for
Asbestos (Williams et al. (2007; Paustenbach et al.
(2004b). The SACC noted that a summary table of
published air measurements associated with brake
maintenance can be found in Attachment 3 of public
comments by Arthur Frank. Recommendation 27: Use
the occupational hygiene measurements reported for the
brake shops in Columbia.
PUBLIC COMMENTS:
• EPA does not know the actual number of workers in the
US who are currently exposed to asbestos from working
directly with asbestos-containing brakes or clutches.
• EPA presents no information regarding the actual
number of vehicles in the US that contain asbestos-
containing brakes or clutches.
• Further review and discussion of all available datasets
for deriving the 8-hour TWA, high-end exposure, the
short-term, central tendency exposures, and the 8-hour
TWA, central tendency exposures for this COU are
needed, including a clearer rationale for why certain
studies and data points were included (versus excluded).
• EPA used concentrations measured during "unpacking
and packing 16 boxes of asbestos-containing brake pads
over approximately 30 minutes" for the high-end
exposure value for occupational and DIY vehicle brake
work (Draft RE for Asbestos p. 94 of 310); this
concentration is not a reasonable surrogate for either.
Moreover, the short-term sample collected by Madl et
al. (2008) was a 15-minute sample (not a 30-minute
sample), so the associated exposure concentrations in
the Draft RE for Asbestos are overestimated. One
generally does not extrapolate measured concentrations
for a job or task to another job or task that differs in
fundamental ways (e.g, materials, handling procedure,
encountered in U.S. vehicles differs from what is seen in
other countries. In Section 2.3.1.7 of Part 1 of the Risk
Evaluation for Asbestos, EPA explains the focus on post-
1980 publications that reported original asbestos PBZ
measurements for business establishments in the U.S.
EPA reviewed publications suggested in comments from the
public and the SACC. EPA has included relevant
occupational exposure data to reflect the new information
obtained and clarified why some of the suggested references
are not cited in the risk evaluation.
EPA revised text in Section 2.3.1.7.3 of Part 1 of the Risk
Evaluation for asbestos to reflect a market share adjustment
based on the dollar value of imported brakes identified as
containing asbestos. EPA has been unable to identify
reasonably available information to determine the number of
potentially exposed workers and the proportion of vehicles
with asbestos-containing brakes or clutches.
With regard to the inclusion of Madl et al. (2008) which
includes the measurements taken during opening and closing
boxes, EPA considers opening and closing boxes to be part
of the overall brake replacement process and has retained
Madl et al. (2008) in Part 1 of the Risk Evaluation for
Asbestos. This is consistent with other COUs (chlor-alkali
and sheet gaskets) where measurements taken during the
handling of packages containing asbestos and asbestos
containing articles were included in the exposure estimates.
Section 2.3.1.7.4 has been revised to provide the rationale for
including this study.
The highest concentration was from a 15-minute average
sample and therefore might overstate (by no more than a
factor of two) the 30-minute concentration.
EPA included data from Blake et al. (2003) for arc grinding
of brakes, a practice common decades ago, but noted that the
concentrations were likely overestimates of current
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processes, durations, frequencies, etc.) without at least
recognizing and adjusting for such differences.
Moreover, the maximum value obtained from a single
study is unlikely to represent high-end exposures for an
entire population of workers. In the Madl et al. (2008)
study, the 30-minute asbestos concentrations ranged 13-
fold, while the 15-minute asbestos concentrations
ranged 40-fold.
EPA based its high-end exposure on data collected
during arc grinding of brakes without dust control; arc
grinding has not been a common practice since the
1960s (NIOSH (1989V
EPA used the maximum value from Madl et al. (2008)
even though elsewhere in the Draft RE for Asbestos,
EPA states that the Agency uses "95th percentile"
estimates to represent high-end exposures for COUs"
unless not available" (p. 57). Table 1 of Madl et al.
(2008) presents the data by which the 95th percentile
value {i.e., 0.366 f/cc) can be calculated.
EPA selected the highest 8-hour TWA personal
breathing zone result [0.094 f/cc, reported by Blake et
al. (2003)1 as one of the bases of their "high-end" 8-
hour TWA exposure for occupational brake repair work.
This sample, however, was collected for 103 minutes
during the arc grinding of drum brake shoes. Arc
grinding stopped mid 1980s and is unlikely today.
Moreover, Blake et al. (2003) conducted a simulation
study to recreate historical airborne asbestos
concentrations, which is not appropriate for predicting
future exposures.
Moreover, Bernstein et al. (2015); Bernstein et al.
(2014) showed that samples of dust from arc grinding
are not biologically active.
Currently, one car manufacturer imports asbestos-
containing brakes for use in a single model of vehicle
which is manufactured domestically, but only exported
conditions (Section 2.3.1.7.4). EPA believes this study
warrants inclusion because it also received feedback from
commenters (see next comment and EPA response) that arc
grinding of brakes still occurs today.
EPA used the highest exposure concentration from Madl et
al. (2008) in the risk evaluation. A comment recommended
that EPA instead calculate the 95th percentile concentration
using data reported in Table 1 of this article. However, Table
1 does not present all individual sampling results, which
would be needed to calculate the distribution percentiles.
Regarding asbestos-containing brakes for car manufacturing,
EPA did not include an estimate of the number of workers
who install asbestos-containing brakes at the one domestic
car manufacturer still known to install them. Regarding
clutches, EPA is not aware of any car manufacturers that
import asbestos-containing clutch assemblies. EPA has
revised Section 2.3.1.7.1 accordingly.
EPA acknowledges that it received some comments
suggesting that exposures were underestimated and others
suggesting that exposures were overestimated. EPA
evaluated the full range of data sources submitted in
comments from the public and SACC, but no additional
studies were identified for inclusion related to over- or
underestimation of exposures. EPA has revised Section
2.3.1.7.4 to acknowledge that the suggested literature did not
meet EPA's selection criteria.
EPA revised Section 2.3.1.7.1 to indicate the information
available to provide further historical context, but EPA did
not find it necessary to add this context in Part 1 for the Risk
Evaluation for Asbestos.
EPA does not have information on what fraction of dust
from arc grinding is "active" asbestos. However, there is
information indicating that dust from brake repair contains
30 to 55% unaltered chrysotile fibers.
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and sold outside of the US (Draft RE for Asbestos In.
3120-3121, 3126-3127), and EPA presents no
information regarding the number of workers involved
in this activity.
• EPA presents no information that any US automotive
manufacturer is currently importing or installing
asbestos-containing clutches on any vehicles.
• One commenter disagreed and stated that repair of
automotive friction products (brakes and clutches) has
been documented to cause extremely high asbestos
exposures, many times the current OSHA PEL.
In the Draft RE for Asbestos, understanding the difference
between the materials and processes used for a disc brake
versus a drum brake job, and the difference between the
use of a grinder versus an arc grinder, and how / when
these tools are used or if they are used at all, is critical to
interpreting historical sampling data to develop reasonable
exposure scenarios.
httos ://beta.resulations. sov/comment/EP A-HO-OPPT-2019-
0501-0040
EPA believes that the assessment approach used for
replacement auto brake COU is appropriate and reasonable.
2.34 Aftermarket automotive brakes ONU exposure estimates
SACC,
40, 42,
51,80,
90, 95
SACC COMMENTS:
• In the automotive brake repair COU, the studies used
for estimating ONU exposure are simulated surrogate
(unpacking) activities rather than actual brake repair in
a working establishment. In one study, the surrogate
exposure involved unpacking boxes of brake pads,
shoes etc. (Madl et al. (2008). Whether the exposures
seen in that study mimic those in actual car repair
facilities is unclear. The SACC suggested other studies
that might be superior.
• Casual online searches by SACC members found that
arc grinding of brake shoes is likely occurring in 2020
(see YouTube®, eBay®). Moreover, brief searches on
eBay produced multiple listings for new asbestos brake
pads for both automobiles and motorcycles. Some
EPA's response to Comment 2.33 addresses the inclusion of
Madl et al. (2008), which has been retained in Part 1 of the
Risk Evaluation for Asbestos.
EPA has retained the study on arc grinding of brakes (Blake
et al., 2003) in the exposure assessment because there is
information indicating that this activity still occurs. EPA
does appropriately note in Part 1, however, that this is not a
common activity.
EPA has identified and described evidence of one car
manufacturer using asbestos-containing brakes, however, the
extent to which asbestos remains in aftermarket replacement
parts is difficult to characterize. EPA evaluated
epidemiologic studies of lung cancer and mesothelioma in
auto mechanisms and did not find those studies sufficient for
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sellers list wholesale quantities while others list "new
old stock." Given ongoing commerce in asbestos pads
in many foreign countries, it is unlikely that all asbestos
brake pads are counterfeits.
PUBLIC COMMENTS:
• Other commenters stated that EPA ignored relevant
studies and overestimated exposure. The five NIOSH
studies cited by EPA contain both personal and area
sampling data that could be used to assess potential
bystander exposures during brake repair work should be
considered.
• The number of workers or consumer DIY users of
imported chrysotile-containing aftermarket automotive
brakes/linings are unknown. Import volumes and the
number of asbestos-containing brakes purchased online
and installed in classic or new cars is unknown (p. 17-
18, 22). EPA's "best current estimate" of 749,900 auto
mechanics in the US is from 2016 BLS (p. 92). If each
mechanic performs multiple brake jobs in a day, few
could possibly use imported chrysotile-containing
brakes daily.
• Far less than <1% of brakes imported from other
countries might contain asbestos, and virtually all of
those should be brake pads (rather than drum brakes) for
which there should be no exposure during installation or
removal.
• Few older or antique model vehicles that might have
asbestos-containing parts are still in operation. The
Draft RE for Asbestos (p. 3121-3124) provides no
evidence that there are asbestos-containing brakes
installed by consumers.
• Finlev et al. (2013); Finlev et al. (2012) provides
reasonably accurate descriptions of the number of
mechanics who might be exposed to asbestos from
brakes and describes limitations of Dr. Lemen's
analysis.
use in deriving in IUR to develop risk estimates. The
evaluation of these studies and their limitations is described
in a Supplemental File for this Response to Comments
document.
EPA used the NIOSH "bystander" measurements to derive
updated ONU exposure estimates for this COU, as described
in Section 2.3.1.7.5.
EPA made adjustments to the estimated number of
individuals exposed using reasonably available information
on the potential market share of asbestos brakes. Details are
in provided in Section 4.3.7, but the new estimate for number
of both workers and ONUs is based on the assumption that
asbestos brakes may represent only approximately 0.05% of
aftermarket automotive brakes. EPA
EPA estimated potentially exposed individuals (both workers
and ONUs) by applying this factor (0.05%) to the universe of
automotive service technicians and mechanics.
Regarding the suggested publications by Finley et al., the
first publication compared reported to expected cases of
mesothelioma for automotive mechanics—and had to
estimate the total number of mechanics to do so. Bureau of
Labor Statistics data were used for this purpose, which is the
same data source that EPA used in the risk evaluation. The
second publication is a letter to the editor, which is a
response to a criticism of the first publication. The letter to
the editor does not include further detail on the estimated
number of workers.
Regarding the assertion that asbestos-containing brake
materials purchased in 2008 does not imply they are
available in 2020, EPA does not make contradictory
statements. However, EPA clarifies that asbestos containing
brakes are still available online for purchase.
EPA has updated Section 2.3.1.7.5 to clarify how central
tendency exposure estimates were derived for the
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• The fact that asbestos-containing replacement brake
materials and clutch discs were purchased in 2008 from
an auto parts facility (Draft RE for Asbestos pp. 3201-
3203, pp. 3248-3251) does not indicate availability or
actual use of such parts in 2020.
• How EPA derived the 0.006 f/cc value is not clearly
explained in the Draft RE for Asbestos. EPA should
outline the calculation steps and identify the location of
the "central tendency" data for each study.
• Inherent in the use of the 0.006 f/cc value is the
assumption that every brake job performed over the
course of a brake repair mechanic's 40-year career will
involve the removal/installation of asbestos-containing
brakes. These are obsolete and extreme scenarios that
are not "reasonable" for present and future brake repair
work. The commenter suggested that EPA consider
incorporating a factor that accounts for the small
fraction of brakes currently present on vehicles or in
commerce that contain asbestos.
aftermarket automotive parts condition of use. That text
reads: "The central tendency short-term TWA exposure
value for workers is based on the seven studies found to
include relevant measurements.. .For each study, EPA
identified the central tendency short-term exposure, which
was either reported by the authors or inferred from the range
of data points, and the value in Table 2 15. (0.006 fibers/cc)
is the median of those central tendencies from those seven
studies. Thus, three of the studies reported central tendency
concentrations lower than 0.006 fibers/cc, one reported a
central tendency concentration of 0.006 fibers/cc, and the
other three studies reported higher exposure concentrations."
2.35 Worker exposures for brake installation on export vehicles unlikely to match aftermarket brake installation ONU
42, 79
PUBLIC COMMENTS:
• EPA exposures for installing brakes and clutches in
exported cars from an 8-hour TWA exposure (from
Draft RE for Asbestos Table 2-15) before consideration
of PPE and any relevant APF. Since those exposures
were assumed to be the same as for repairing or
replacing brakes, the resulting risks appear to be
identical despite the different work environment for
installing new brakes or new brake assemblies on new
cars for export and for "repairing or replacing brakes
with asbestos-containing aftermarket automotive parts."
• One commenter recommends a oaoer bv Donovan et al.
(2011) for bystanders, although it is unlikelv a worker
EPA did not identify reasonably available information on the
exposure associated with installing brakes and clutches in
new cars and used the data used for aftermarket auto brake
replacement COU.
The aftermarket auto replacement brake and clutch estimates
include monitoring data from the following worker activities:
packing and unpacking boxes, cleaning, removal of old parts,
and installation of new parts.
The air measurements indicate asbestos is present in the
workplace air during all activities.
Although there are differences between new car installation
and old car replacement, there are similarities in worker
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would install an asbestos-containing brake (that might
release dust).
activities: packing and unpacking boxes, cleaning, and
installation of new parts.
EPA believes that the assessment approach used for the new
car installation is appropriate and reasonable.
EPA has revised the ONU derivation such that it is based on
sampling data that NIOSH collected at bystander locations
during brake repair activity. Section 2.3.1.7.5 in Part 1 for
the Risk Evaluation for Asbestos describes how EPA derived
the ONU exposure estimates from the NIOSH data.
2.36 Workers engaged in clutch repair have lower exposures than brake mechanics
90
PUBLIC COMMENTS:
• Clutch wear debris has historically contained
approximately 10-fold less asbestos than brake wear
debris (Draft RE for Asbestos, p. 91); newly
manufactured clutches have not contained asbestos for
the last several decades; and only one clutch needs
replacement compared with four brakes. Thus, exposure
data from brake repair environments does not apply and
would overestimate clutch repair exposure.
• Moreover, "a common clutch repair method is to
remove and replace the entire clutch assembly, rather
than the clutch disc component" (Draft RE for Asbestos
p. 92), which eliminates potential asbestos exposure.
• There should be negligible exposures to brake dust
released during drum grinding or brake wear debris (due
to historical braking) in the coming years.
• The vast majority of vehicles undergoing clutch
maintenance today and in future will have automatic
transmissions, rather than manual transmissions.
Automatic transmission bands and clutch plates are
considered wet parts, bathed in transmission fluid
throughout the lifetime of the transmission. Thus,
EPA revised Section 2.3.1.7.2 in Part 1 of the Risk
Evaluation to address additional details on clutch
replacements and asbestos exposure (e.g, vehicles having
just one clutch assembly).
In Section 2.3.1.7.2, EPA originally noted that asbestos
exposures for clutch repair are known to be lower than the
exposures for brake repair. EPA determined that the asbestos
air concentrations during clutch repair are comparable to
those during brake repair. EPA clarified the text accordingly.
Furthermore, EPA has considered the studies and updated
Section 2.3.1.7.4 of Part 1 of the Risk Evaluation for
Asbestos.
EPA did not add language to forecast future exposures to
brake dust as "negligible", given that asbestos in automotive
parts is not banned at the federal level, and foreign suppliers
face few restrictions when selling asbestos-containing brake
products to business establishments and individuals in the
United States.
Finally, EPA acknowledges the comment asserting that
worker 8-hour TWA asbestos exposures to aftermarket
automotive brakes "ranged from 0.004 f/cc to 0.008 f/cc (for
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potential exposure of workers to asbestos in air should
be much lower.
• A comprehensive review of asbestos exposure
associated with brake repair work conducted in the
1980s (in the absence of compressed air use) reported
that the mean 8-hour TWA exposures for car and light
truck brake repair ranged from 0.004 f/cc to 0.008 f/cc
(for garages with a "low" level/frequency of service)
(Paustenbach et al. (2003), while mean 8-hour TWA
exposures for clutch repair ranged between 0 f/cc and
0.0016 f/cc (Blake et al. (2008; Cohen and Van Orden
(2008). Given the availability of clutch repair exposure
data in the peer-reviewed literature, any health risk
assessment for clutch repair activities should rely on
these data.
garages with a 'low' level/frequency of service)" EPA notes
that its central tendency estimate (0.006 f/cc) falls within this
range.
2.37 Other gaskets/utility vehicles (UTVs) worker exposure estimates
SACC
SACC COMMENTS:
• The study used for other gaskets/UTVs is a research
simulation study on automobile exhaust systems rather
than actual UTV maintenance data.
• The relevant UTV work is not adequately described
regarding the state of the UTV components at
replacement/repair and difficulty of their removal.
Given the Draft RE for Asbestos estimate of the large
number of UTV sales and service facilities, the SACC
recommended using unannounced site visits to observe
the processes.
• Discussion of motorcycle brake pads led to further
consideration of other vehicles or equipment that might
contain asbestos brake or clutch pads such as tractors or
other farm equipment, construction equipment, buses
and commercial trucks, forklifts, cranes, etc. One SACC
member reported that one of the public commenters had
provided data that included some asbestos content
EPA clarifies that the principal data source for the UTV
gasket servicing COU was data from Paustenbach et al.
(2006). While the title of the Paustenbach et al. (2006) paper
does refer to "a simulation study," the paper documents a
field sampling program at an operating muffler shop, while
workers repaired vehicle exhaust systems. This paper was
selected as the principle data source because the UTV COU
also pertains to asbestos-containing components in exhaust
systems. In short, the study data are direct measurements
from relevant work activities.
Part 1 of the Risk Evaluation focuses on the COUs for which
EPA could determine the presence of chrysotile asbestos in
friction materials is intended, know, or reasonably foreseen
to occur. When developing the risk evaluation, EPA
reviewed several publications noting that asbestos was
previously found in various other types of vehicles, but EPA
has no evidence of its current use in other types of vehicles.
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analysis and air fiber concentration data for non-
passenger car products.
Accordingly, EPA did not revise the COUs for the risk
evaluation.
2.38 Consideration of additional studies on gasket use identified by SACC
SACC
SACC Comments
• Recommendation 79: Discuss and incorporate findings
from the additional studies on gasket use identified by
SACC (numbers 1 through 5 below):
• 1. Cowan et al. (2015) as cited in the Draft RE for
Asbestos (p. 91-92) noted results of 19 samples taken
by OSHA during inspections of auto repair facilities
between 2000 and 2011. One SACC member
commented that this number of inspections is barely
adequate to support any conclusions about asbestos
exposure and the tasks performed during sampling were
not reported. Draft RE for Asbestos Table 2-14
showing data from Cowan et al. (2015) can be
summarized in text, if retained.
• 2. The five reports published by NIOSH in 1987 and
1988 and the associated summary cited by EPA on page
92 demonstrated that asbestos exposure in brake repair
facilities can be lowered by specific dust-lowering work
practices. However, without knowing the actual
prevalence of these practices in auto repair facilities at
present, the relevance of these findings is unclear.
• 3. The risk evaluation relies heavily on a few
publications on brake-related exposures, especially
Blake et al. (2003), which was a simulation of brake
repair work. It cited Madl et al. (2008) which did not
pertain to actual brake repair but to dust levels
associated with packing and unpacking dozens of boxes
EPA will retain its review of Cowan et al. (2015) paper (and
the summary table) in Part 1 of the Risk Evaluation for
Asbestos. However, EPA does acknowledge that this paper
includes a relatively small number of sampling events, which
is why EPA did not base the COU evaluation on this paper
alone. EPA used this paper to provide context for OSHA
sampling activities in recent years.
EPA agrees that the NIOSH studies were performed to assess
the effectiveness of different types of controls. EPA has
added language to Section 2.3.1.7.6 in Part 1 of the Risk
Evaluation for Asbestos to note that it is unclear how many
brake mechanics currently use those techniques (though
these workers would still be required to use dust control
methods as required by the OSHA asbestos standard).
EPA notes that it reviewed all relevant publications in the
systematic review process. However, when deriving
exposure estimates, EPA focuses only on publications that
(1) present asbestos exposure data for U.S. establishments,
(2) review sampling data collected from 1980 to the present,
and (3) present original data (as opposed to summarizing
previously reported results). EPA reviewed every reference
mentioned in the public comments and peer review
comments. None of those studies meet the three selection
criteria that EPA notes here. (Note: The NIOSH (1982) and
Rohl et al. (1976b) studies are based on samples collected
prior to 1980.) EPA acknowledges that sampling data from
earlier years reported higher asbestos concentrations, but
those data were also collected before OSHA promulgated
asbestos standard requirements specific to brake repair work.
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of new brakes. It mentioned a Weir and Meraz (2001)
study but rejected use of its data for lack of details.
• 4. EPA failed to cite other highly relevant studies (page
92) including the NIOSH (1982) and Rohl et al. (1976b)
studies which represented sampling performed at active
repair facilities. Both studies showed higher levels of
asbestos exposure for brake mechanics and others in the
area of brake mechanic work. These studies may also
more accurately reflect working conditions in current
marginal repair shops that use asbestos-containing
brakes.
• 5. The Draft RE for Asbestos stated that PCM may
overstate asbestos fiber concentrations (citins Blake et
al. (2003) and Weir and Meraz (2001)) but ignored Rohl
et al. (1976b) and failed to cite NIOSH (1982) and
Sheehv et al. (1989), which both show that asbestos
fibers counted by TEM are greater than those counted
by PCM.
• The Draft RE for Asbestos (pp. 78-79), cited just two
published studies of gasket removal and used Chemours
sampling data (which lack critical documentation).
SACC suggested EPA consider four additional studies
with respect to sasket use including Chens and
McDermott (1991), Lonso et al. (2002), Mckinnerv and
Moore (1992) and Millette et al. (1995).
EPA has added text in Section 2.3.1.7.4 explaining how the
Agency arrived at its final list of publications for review.
EPA revised Section 2.3.1.5.4 to acknowledge the broader
range of literature available on sheet gasket removal that the
Agency considered. However, EPA ultimately decided to
base its assessment on worker exposure data collected in the
one industry that was known to continue using asbestos-
containing sheet gaskets.
2.39 Other gaskets/utility vehicles (UTVs) ONU exposure estimates
SACC,
42,51,
61, 69,
79
SACC COMMENTS:
• The Paustenbach et al. (2006) studv is a research
simulation rather than actual UTV maintenance data.
PUBLIC COMMENTS:
• Even though there are some asbestos-containing gaskets
still in UTVs, removal of them under any plausible
Refer to EPA's response to comments in Section 2.36 for
more information regarding the use of Paustenbach et al.
(2006).
EPA will continue to base its exposure estimate for the UTV
COU on the values cited in the draft risk evaluation. One
suggestion in this comment was to use measurements from
removal of a gasket from a flange seal and cutting asbestos-
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scenario produces low airborne concentrations of
chrysotile.
• There is no information from OSHA, NIOSH, or the
scientific literature by which to estimate the number of
persons possibly exposed or their exposures with
installing and servicing gaskets in UTVs.
• One commenter tested removal of chrysotile-
impregnated elastomeric matrix (styrene butadiene
rubber) gaskets from a flange seat and reported their
results. The cutting of chrysotile packing with
"snippers" resulted in a PCM measurement of < 0.01
f/cc of air and TEM measurement less than the LOD (<
0.001 f/cc of air).
• EPA did not find relevant data from OSHA or NIOSH.
The Paustenbach et al. (2006) studv involved
replacement of exhaust gaskets. In that study, 17 of 23
personal samples and 16 of 21 area samples were ND.
The study calculated an 8-hour TWA exposure
concentration of 0.01 fibers/cc based on a worker
performing four exhaust system removal tasks in one
shift. EPA could use these data instead of extrapolating
from short task or sampling intervals.
containing packing with "snippers." The exposure estimates
in the draft risk evaluation are expected to be comparable or
high than any "low airborne concentration" exposure
scenarios commenter mentioned.
EPA clarifies that, as stated in the Draft RE for Asbestos, no
data from OSHA, NIOSH, or the scientific literature report
the number of workers involved in servicing UTVs and their
asbestos exposures. In such cases, EPA seeks alternate data
to characterize these values. Part 1 of the Risk Evaluation for
Asbestos documents all assumptions related to the use of
alternate data.
EPA does not believe the information provided for asbestos
concentrations associated with removal of asbestos-
containing gaskets from a "flange seal" using "snippers." is
directly relevant to the UTV COU. In contrast, the
Paustenbach et al. (2005) publication has greater relevance,
as that is the only study EPA identified that evaluated
asbestos releases from the removal or repair of vehicle
exhaust systems with asbestos-containing gaskets. While the
Paustenbach study pertains to motor vehicles, EPA believes
this data set has the greatest relevance to repair of
ATVs/UTVs known to have asbestos-containing gaskets in
their exhaust systems
2.40 Requirement or assumption of use of personal protective equipment (PPE)
SACC,
6,31,
43,51,
63, 65,
70, 72,
85, 86,
91, 92
SACC COMMENTS:
• SACC was concerned about the unrealistic inclusion of
respiratory protection and associated assigned
protection factors (APFs) for risk estimation for workers
(Draft RE for Asbestos Table 4-55, p. 208). Respiratory
protection programs, as established and operated by
some employers, are inadequate. Citation by OSHA for
inadequate respiratory protection programs is one of the
EPA agrees that there are challenges associated with use of
PPE; they are described in Section 5.1. By providing risk
estimates that account for use of PPE, EPA is not
recommending or requiring use of PPE. Rather, these risk
estimates are part of EPA's approach for developing
exposure assessments for workers that relies on the
reasonably available information (including information
from the industry) and expert judgment. When appropriate,
EPA will develop exposure scenarios both with and without
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five most common OSHA violations nationally over the
past several years.
Even when PPE may be used, it is sometimes
incorrectly used, or a lower PPE standard is used (e.g,
use of N95 respirators in the sheet gasket stamping
operation which OSHA considers inappropriate) (Draft
RE for Asbestos p. 161).
Given the uncertainty around availability, use, and
effectiveness of appropriate respirator protection, some
SACC members recommended deleting the APF's in
the exposure estimates and risk calculations (remove
from Table 4-55). Another member, however,
considered it appropriate to present risk with and
without PPE because there are industries and individual
facilities that comply with respiratory protection
protocols. Recommendation 61: Clarify in Table 4-55
that risks under PPE use are potentially unachievable
lower bounds that assume a comprehensive respiratory
protection program is always in place everywhere.
Most of the airborne asbestos concentrations used to
estimate worker exposures in Draft RE for Asbestos do
not exceed OSHA action levels and therefore would not
trigger enforcement of a proper respiratory protection
program.
As noted in the Draft RE for Asbestos (p. 64-67), ACC
documentation from chlor-alkali plants reported
respiratory protection is not used in certain tasks even
when air sampling shows asbestos fiber concentrations
that approach the OSHA STEL, i.e., cell assembly,
hydro-blasting.
Small businesses are unlikely to have a respiratory
protection program, either because they believe that
they are not covered by OSHA or because they do not
have the resources to establish such a program. Draft
RE for Asbestos Table 2-7 (p. 68) summarizes the
short-term sampling results from industry.
engineering controls and/or PPE that may be applicable to
particular worker tasks on a case-specific basis for a given
chemical. EPA did assess the risk to workers in the absence
of PPE, and those risks are presented in Section 4 Risk
Characterization under Table 4-55, Summary of Risk
Estimates for Inhalation Exposures to Workers and ONUs by
cou.
While EPA has evaluated worker risk with and without PPE,
as a matter of policy, EPA does not believe it should assume
that workers are unprotected by PPE where such PPE might
be necessary to meet federal regulations, unless it has
evidence that workers are unprotected. For the purposes of
determining whether or not a COU presents unreasonable
risks, EPA incorporates assumptions regarding PPE use
based on information and judgement underlying the exposure
scenarios. These assumptions are described in the
unreasonable risk determination for each COU, in Section
5.2. Additionally, in consideration of the uncertainties and
variabilities in PPE usage, including the duration of PPE
usage, EPA uses the high-end exposure value when making
its unreasonable risk determination in order to address those
uncertainties. EPA has also outlined its PPE assumptions in
Section 5.1 in addition to 5.2
In the case of sheet gasket stamping, EPA did take into
account in Section 5.2 the ineffectiveness of N95 respirators
for reducing asbestos fiber exposure and assumed an APF of
1 (or no reduction in the risk estimate) to reflect this
consideration. EPA also took into account that ACC
documentation reported respiratory protection was not used
in certain worker tasks even when monitoring data showed
the presence of airborne asbestos fibers. Section 5.2 also
reflects this and assigns an APF of 1 when considering risks
to chlor-alkali workers. Further, other COUs presented in
Section 5.2 take into the account the absence of PPE where
EPA had information to make this determination.
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• The Draft RE for Asbestos concludes that "even with
every worker wearing (a) respirator, some of these
workers would not be protected" (p. 60, In. 2098-2099)
and SACC agrees.
• For risks to workers that assume use of PPE, the Draft
RE for Asbestos uses the APF (assigned protection
factor) for the respirator as though it were a limit.
OSHA sets APF for a respirator, however, based on
whether 95% of the samples in the studies achieved that
APF. That does not address personal differences (e.g,
Crump (2007)). for example a worker whose respirator
does not fit well may receive far less protection from
the respirator than indicated by the assigned APF.
• SACC described various limitations associated with the
use of the APFs in some detail, citing the National
Personal Protective Technology Laboratory as a
resource for realistic protection factors.
Recommendation 88: Consider visiting facilities where
asbestos is processed to increase EPA understanding of
the worker conditions, including PPE use.
• SACC members were of mixed opinions regarding the
specific APFs in Section 2.3.1.2 as stated in their review
(response to CQ 6.2) and as noted by SACC in prior
reviews of chemical DREs. It asked EPA to reconsider
or defend the default assumptions regarding PPE/APF
after reviewing Riala and Riipinen (1998) results and
practical limitations in PPE programs.
• Recommendation 20: Reconsider or defend the default
assumptions regarding PPE and APF use after
considering the Riala and Riipinen (1998) results and
practical limitations in PPE programs.
PUBLIC COMMENTS:
• Given the uncertainty in PPE use and appropriate APFs,
commenters appreciated EPA presenting risks assuming
no PPE. Evaluating risk without regard to respirator use
In addition, as explained in Section 2.3.1.2, for asbestos,
nominal APFs presented in Error! Reference source not f
ound. may not be achieved for all PPE users. Riala and
Riipinen (1998) investigated performance of respirators and
HEPA 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, 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 protection
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 respirator, some of these workers would not be
protected.
Regarding Recommendation 61 to clarify that the risks in
Table 4-55 using PPE are potentially unachievable where
respiratory protection is not comprehensive was addressed in
the DRE using footnote c in the columns where PPE was
applied. Footnote c to Table 4-55 says: "As shown in Table
4-3, EPA has information suggesting use of respirators for
two COUs (chlor-alkali: APF of 10 or 25; and 7430 sheet
gasket use: APF of 10 only). Application of all other APFs is
hypothetical."
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is consistent with prevailing industrial hygiene practices
and OSHA asbestos regulations.
• OSHA and NIOSH emphasize that respirators are not
always properly worn for a variety of reasons. OSHA
inspection data show that the respirator standard is the
fourth most often cited violation even in situations
where respirators are required.
• Assertions in the Draft RE for Asbestos about PPE
should include a discussion on the extent and frequency
that the PPE is used according to requirements.
• The nominal APFs in Table 2-3 may not be achieved for
all PPE users. Riala and Riipinen (1998) found some
workers have protection above nominal APF while
others have below nominal. Even the ACC submissions
for chlor-alkali production indicated that PPE is not
worn throughout an entire shift.
• If the two chlor-alkali facilities had advanced notice of
EPA's 2017 site visit, they might have "cleaned up" for
it. Moreover, EPA did not verify wearing of respirators
or evaluate whether the 2 facilities were representative
of the 15 in the industry.
• The general public might believe that product safety
data sheets exaggerate hazards of asbestos or may not
keep the data sheets for future reference.
• The assumption of respirator use does not change
EPA's conclusions on some COUs, but it does reduce
risk estimates significantly and might justify exposure
restrictions that are insufficiently protective.
• EPA assumed respirator use for three COUs based on
reports by industry, which might not be representative.
EPA also lacked information on the type of respirator
used except for chlor-alkali production and sheet gasket
use. Thus, EPA used largely "hypothetical" APFs of 10-
25.
• EPA considered respirator use either in the entire shift
or not at all. Failure to incorporate current practices
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regarding respirators will lead to an overestimate of
risks to chlor-alkali workers.
2.41 Acute exposure events such as spills and accidents
51, 86
PUBLIC COMMENTS:
• Particularly for asbestos imports for the chlor-alkali
industry, accidents or improper handling could rupture
shipping containers and bags, releasing raw asbestos
powder in quantities that put workers or bystanders at
risk. The Draft RE for Asbestos acknowledges that
damaged shipping containers have arrived in the US and
port and warehouse workers manage and remediate
damaged containers. Spill exposure scenarios include
losses from torn sacks in shipment, unloading and
storage of asbestos sacks, and waste from vacuuming
areas where torn sacks are discovered and patched.
• Thus, it is not appropriate to assume that spills, leaks
and accidents during importation and distribution in
commerce never happen and pose no risk.
• EPA also cautioned that "it is uncertain if certain high-
exposure activities are captured in this dataset, such as
exposures when cleaning spilled asbestos within a
container from damaged bags." EPA had little ability to
verify the completeness of the chlor-alkali data because
it made site visits to only 2 of the 15 plants using
asbestos diaphragm cells, these visits were announced
in advance, and EPA was not accompanied by
knowledgeable experts from OSHA and NIOSH.
EPA gathered frequency of exposure information from the
chlor-alkali industry, both through observations and
discussions during site visits and through written inquiry.
Section 2.3.1.3.2 in Part 1 of the Risk Evaluation for
Asbestos was updated to clarify that industry informed EPA
that facilities receiving damaged bags containing chrysotile
asbestos is a "very rare" event. In addition, Section 2.3.1.3.2
has been updated to include task-specific (e.g, hydroblasting)
data provided by ACC.
EPA believes Section 2.3.1.3.6 pertaining to data
assumptions, uncertainties, and level of confidence for the
chlor-alkali COU in the occupational exposure assessment is
sufficient. As noted above, asbestos spilling from damaged
bags is an infrequent occurrence in this industry. There is not
currently available information available to conduct
quantitative evaluations of this uncertainty for this COU.
EPA does not believe that conducting additional site visits
would not have provided further quantitative insights on
worker exposures during extremely rare events.
Accidents, spills and leaks generally are not included within
the scope of a TSC A risk evaluation because in general they
are not considered to be circumstances under which a
chemical substance is intended, known or reasonably
foreseen to be manufactured, processed, distributed, used, or
disposed of. To the extent there may be potential exposure
from accidents, spills and leaks, EPA is also declining to
evaluate environmental exposure pathways addressed by
other EPA-administered statutes and associated regulatory
programs.
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First, EPA does not identify asbestos accidents, spills or
leaks as "conditions of use." EPA does not consider
accidents, spills or leaks to constitute circumstances under
which asbestos is manufactured, processed, distributed, used,
or disposed of, within TSCA's definition of "conditions of
use." Congress specifically listed discrete, routine chemical
lifecycle stages within the statutory definition of "conditions
of use" and EPA does not believe it is reasonable to interpret
"circumstances" under which asbestos is manufactured,
processed, distributed, used, or disposed of to include
uncommon and unconfined accidents, spills or leaks for
purposes of the statutory definition. Further, EPA does not
generally consider accidents, spills and leaks to constitute
"disposal" of a chemical for purposes of identifying a COU
in the conduct of a risk evaluation.
In addition, even if accidents, spills or leaks of asbestos
could be considered part of the listed lifecycle stages of
asbestos, EPA has "determined" that accidents, spills and
leaks are not circumstances under which asbestos is
intended, known or reasonably foreseen to be manufactured,
processed, distributed, used, or disposed of, as provided by
TSCA's definition of "conditions of use," and EPA is
therefore exercising its discretionary authority under TSCA
section 3(4) to exclude accidents, spills and leaks from the
scope of the asbestos risk evaluation. The exercise of that
authority is informed by EPA's experience in developing
scoping documents and risk evaluations, and on various
TSCA provisions indicating the intent for EPA to have some
discretion on how best to address the demands associated
with implementation of the full TSCA risk evaluation
process. Specifically, since the publication of the Risk
Evaluation Rule, EPA has gained experience by conducting
ten risk evaluations and designating forty chemical
substances as low- and high-priority substances. These
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processes have required EPA to determine whether the case-
specific facts and the reasonably available information
justify identifying a particular activity as a "condition of
use." With the experience EPA has gained, it is better
situated to discern circumstances that are appropriately
considered to be outside the bounds of "circumstances...
under which a chemical substance is intended, known, or
reasonably foreseen to be manufactured, processed,
distributed in commerce, used, or disposed of' and to
thereby meaningfully limit circumstances subject to
evaluation. Because of the expansive and potentially
boundless impacts that could result from including accidents,
spills and leaks as part of the risk evaluation (e.g, due to the
unpredictable and irregular scenarios that would need to be
accounted for, including variability in volume, frequency,
and geographic location of accidents, spills and leaks;
potential application across multiple exposure routes and
pathways affecting myriad ecological and human receptors;
and far-reaching analyses that would be needed to support
assessments that account for uncertainties but are based on
best available science), which could make the conduct of the
risk evaluation untenable within the applicable deadlines,
accidents, spills and leaks are determined not to be
circumstances under which asbestos is intended, known or
reasonably foreseen to be manufactured, processed,
distributed, used, or disposed of, as provided by TSCA's
definition of "conditions of use."
Exercising the discretion to not identify accidents, spills and
leaks of asbestos as a COU is consistent with the discretion
Congress provided in a variety of provisions to manage the
challenges presented in implementing TSCA risk evaluation.
See e.g, TSCA sections 3(4), 3(12), 6(b)(4)(D), 6(b)(4)(F).
In particular, TSCA section 6(b)(4)(F)(iv) instructs EPA to
factor into TSCA risk evaluations "the likely duration,
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intensity, frequency, and number of exposures under the
conditions of use...suggesting that activities for which
duration, intensity, frequency, and number of exposures
cannot be accurately predicted or calculated based on
reasonably available information, including spills and leaks,
were not intended to be the focus of TSCA risk evaluations.
And, as noted in the preamble to the Risk Evaluation Rule,
EPA believes that Congress intended there to be some
reasonable limitation on TSCA risk evaluations, expressly
indicated by the direction in TSCA section 2(c) to "carry out
[TSCA] in a reasonable and prudent manner."
For these reasons, EPA is exercising this discretion to not
consider accidents, spills and leaks of asbestos to be COUs.
Second, even if asbestos accidents, spills or leaks could be
identified as exposures from a COU in some cases, these are
generally not forms of exposure that EPA expects to consider
in risk evaluation. TSCA section 6(b)(4)(D) requires EPA, in
developing the scope of a risk evaluation, to identify the
hazards, exposures, conditions of use, and potentially
exposed or susceptible subpopulations the Agency "expects
to consider" in a risk evaluation. This language suggests that
EPA is not required to consider all conditions of use,
hazards, or exposure pathways in risk evaluations. EPA has
chosen to tailor the scope of the risk evaluation to exclude
accidents, spills and leaks in order to focus analytical efforts
on those exposures that present the greatest potential for risk.
In the problem formulation documents for many of the first
10 chemicals undergoing risk evaluation, EPA applied the
same authority and rationale to certain exposure pathways,
explaining that "EPA is planning to exercise its discretion
under TSCA 6(b)(4)(D) to focus its analytical efforts on
exposures that are likely to present the greatest concern and
consequently merit a risk evaluation under TSCA...." This
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approach is informed by the legislative history of the
amended TSCA, which supports the Agency's exercise of
discretion to focus the risk evaluation on areas that raise the
greatest potential for risk. See June 7, 2016 Cong. Rec.,
S3519-S3520.
As a result, EPA believes it is both reasonable and prudent to
tailor the TSCA risk evaluation for asbestos by declining to
evaluate potential exposures from accidents, spills and leaks,
rather than attempt to evaluate and regulate potential
exposures from such accidents, spills and leaks under TSCA.
2.42 Generalization of occupational exposure based on similar job title and working condition
67, 68
PUBLIC COMMENTS:
• Generalization from certain types of materials, job titles,
work practices, etc. to other workers in similar jobs but
with different exposure profiles based on those
variables, is not appropriate.
• Application of any risk assessment of a given exposure
situation (such as those to which this draft is being
applied, for example theoretical chlor-alkali work
exposures) must consider similarities and differences
between those industrial processes and the differing
processes incorporated in the risk model and resulting
differences in fiber concentrations, types, and
dimensions.
EPA was mindful of this comment when preparing Part 1 of
the Risk Evaluation for Asbestos. However, for all COUs,
the data collected were from workers engaged in the activity
of interest; and if not, limitation and uncertainties associated
with use of surrogate data were noted.
2.43 Suggestions for alternative information
16, 34,
51,69,
65, 73,
82
PUBLIC COMMENTS:
• Should Bureau of Labor Statistics and other available
data on chemical industry worker tenure be used in
EPA has employed a consistent approach for exposure
scenarios for multiple recent risk evaluations conducted
under TSCA. EPA is not aware of specific data for each
COU to allow for application to specific asbestos-related
jobs.
EPA received a wide range of comments on over- and
underestimation of occupational exposures, which have been
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developing central tendency and high-end worker
exposure durations?
• The draft risk evaluation lacks meaningful exposure
monitoring data for nearly all the COUs it addresses.
• EPA should review inspection data from OSHA and the
OSHA-approved state plans for employer violations of
the agencies' asbestos standards. In any given year, less
than 1% of all workplaces will be inspected by federal
or state OSHA compliance officers.
addressed for relevant COUs in previous responses to public
and SACC comment in this Response to Comment
document.
EPA carefully considered all input received and reviewed all
publications that were provided in comments from the public
and the SACC. Through this effort, EPA believes the Part 1
of the Risk Evaluation for Asbestos is based upon the best
available science.
EPA clarifies, again, that evaluation of compliance with
OSHA's standards and the protectiveness of the PELs is not
the purpose of risk evaluations conducted under TSCA.
2.44 Requirements for maximum number of "worst case" input parameters for a given use
83,91,
100
PUBLIC COMMENTS:
• The risk estimates presented for chlor-alkali workers are
not "central tendency" or "high-end" estimates. Instead,
several worst-case assumptions are used as exposure
assessment factors, which results in a significant
overestimate of exposure and risk. EPA needs to
redefine the combination of exposure factors for the
central tendency and high-end scenarios such that they
better represent worker exposures in the chlor-alkali
industry.
• One commenter recommended probabilistic exposure
assessment to comply with best scientific practices.
Given that multiple conservative assumptions can skew a
model or monitoring data to high-end exposure scenarios
that do not represent realistic possibilities, a commenter
suggested that EPA draft guidance on best practices for
high-end exposure estimates, including guidance on the
maximum number of "worst case" input parameters for a
given use.
EPA does not believe it is appropriate to view the exposure
estimates as "worst-case." EPA believes it has sufficiently
characterized the key assumptions, uncertainties and
confidence for occupational exposure estimates for each
occupational COU.
Risk Evaluations for the First 10 Chemicals completed under
TSCA are based on deterministic risk assessment. EPA will
consider the feasibility and appropriateness of using
probabilistic risk assessment for future documents.
EPA will consider the need for guidance for evaluating
worst-case conditions when conducting future risk
evaluations under TSCA
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2.45 Revisit assumptions and data for realism of high-end exposures
SACC,
65, 79,
90, 91,
100
SACC COMMENTS:
• SACC appreciated the segregation of full-shift and
short-term estimates presented in Table 2-24 (Draft RE
for Asbestos p. 106). However, full interpretation of
exposures requires information on how frequently
individual workers participate in specific tasks, and
knowledge of the facility monitoring program strategy,
including how activities are selected for monitoring and
how frequently they are sampled. The absence of this
information increases uncertainty regarding "high end"
exposure characterization. Capturing "off-normal"
events is a continuing problem in occupational hygiene
measurement, and it is not clear that the data sets
available for asbestos COU exposures are fully
representative of actual work conditions.
• Use of area samples is also questionable when
worker/ONU exposures are disproportionately due to
specific but sporadic point source activities. The short-
term sample results provided in the Draft RE for
Asbestos show that specific activities could produce
elevated short-term exposures. ONU exposures might
occur closer to the source than indicated by general
environment area monitoring results.
• Recommendation 21: Identify the frequency of hish
exposure activities (e.g, cleaning asbestos from
damaged bags).
PUBLIC COMMENTS:
• One commenter disagreed and suggested that area
monitoring does not generally yield lower airborne
concentrations than personal monitoring; area monitors
EPA believes its approach relied upon the best available
science, while acknowledging uncertainties and limitations
of available data. Moreover, EPA evaluated all data sources
suggested in comments by the public and the SACC and
updated its evaluations where appropriate. The fact that the
data may be missing rare, peak exposures or "off normal"
events is not viewed by EPA as a critical data gap for Part 1
of the Risk Evaluation for Asbestos, given that the focus of
the evaluation is on health risks associated with chronic
exposures to chrysotile asbestos.
Generally, EPA used representative worker exposure
monitoring data for ONU analysis, whenever those data were
reasonably available. In all other cases, EPA investigated the
range of alternate data sources and selected the ones that
offer the most reasonable insights into potential ONU
exposures—and this included review of area sampling
studies. Part 1 of the Risk Evaluation for Asbestos will
continue to follow this approach but acknowledges the
limitations of using area sampling data.
EPA gathered frequency of exposure information from the
chlor-alkali industry, both through observations and
discussions during site visits and through written inquiry.
EPA updated Section 2.3.1.3.2 to indicate that the frequency
of receiving damaged bags of chrysotile asbestos is a "very
rare" event. Section 2.3.1.3.2 was also updated to reflect
task-specific data provide by ACC, of which hydroblasting
has the highest 50th percentile asbestos PBZ concentrations
of all worker activities.
EPA clarifies that calculations in the Draft RE for Asbestos
are not based solely on studies involving techniques used
from approximately 1940 to 1980. In fact, by excluding
publications with samples collected before 1980, EPA
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are usually placed in locations with the highest expected
concentrations, and where workers rarely spend time.
• EPA states that it assumes modern era control
technologies for brake changes. However, all the
calculations in the Draft RE for Asbestos are based on
studies involving techniques used from approximately
1940 to 1980.
• Some of the assumptions for those working with gaskets
and brakes are not reasonable. Instead, in asbestos-
containing brakes and gaskets, the asbestos is not
friable; old gaskets are unlikely to still be in any active
industrial factory; and gaskets are removed as a single
unit or in large chips, making respirable airborne fibers
unlikely.
• Cowan et al. (2015) (page 627) indicates that OSHA
compliance measurements are not random samples of
workplace conditions, nor do they represent an
industrial hygiene risk management strategy. The
OSHA compliance sample is a snapshot in time,
providing a yes or no answer to the question of whether
a specific worker exposure scenario complies with the
regulatory standards over an 8-hour shift.
• EPA assumes for the indoor scenario that a consumer
might use compressed air to clean brake assemblies;
however, no mechanic would want to blow the dust out
in a garage.
• Use of PCM analysis throughout the risk assessment at
such low levels biases the risk assessment because non-
asbestos fibers, which exist in background air, cannot be
distinguished from asbestos fibers. For example, one
study found that most fibers from removal of asbestos
gasket material in good condition (group A) as
determined by PCM originated from glass fiber
insulation as determined by TEM Spence and Rocchi
(1996).
purposefully did not include data "based on techniques used
decades ago." More specifically, EPA notes that the NIOSH
studies on aftermarket automotive brakes examined
techniques (engineering controls and work practices)
specified in OSHA's asbestos standard for automotive brake
and clutch inspection, disassembly, repair, and assembly
operations.
EPA identified sampling events for brake repair and gasket
replacement that detected release of respirable fibers. Thus,
despite the factors that can limit release of asbestos during
brake repair and gasket replacement, EPA did not find
reasonably available information to conclude those factors
eliminate the releases.
EPA agrees that Cowan et al. did not include measurements
from a random sample of workplace conditions, but EPA
clarifies that it did not rely solely on the Cowan et al. (2012)
publication when evaluating aftermarket automotive brakes.
In fact, most of the data for this COU is from NIOSH studies
that were designed to characterize actual workplace
conditions. Therefore, the limitations of Cowan et al. (2012)
do not warrant revision to EPA's characterization exposure.
EPA agrees that compressed air blowdowns should not
factor into the occupational exposure assessment for
aftermarket automotive parts. Section 2.3.1.7 of the draft risk
evaluation explained why the occupational exposure
assessment did not include any exposure data collected
during compressed air use. However, compressed air use did
factor into the consumer/DIY exposure assessment.
Section 2.3.1.7 notes that for occupational exposure for this
COU, the use of compressed air as a work practice will not
be considered because, in addition to the EPA current best
practice guidance (EPA-747-F-04-004). there is a provision
in the OSHA Asbestos Standard: 29 CFR
§1910.1001 (f)( 1 )(ix): Compressed air shall not be used to
remove asbestos or materials containing asbestos unless the
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• Regarding the exposure point concentration, one
commenter recommended EPA use the mean
concentration instead of the 95th percentile for the high-
end scenario, consistent with EPA's 2008 Framework
for investigating asbestos contaminated Superfund sites.
compressed air is used in conjunction with a ventilation
system which effectively captures the dust cloud created by
the compressed air.
EPA acknowledged limitations in using PCM measurements
in that may count non-asbestos fibers and report them as
asbestos in Section 2.3.1.7.6. EPA believes PCM
measurements are suitable and the IUR derived in Part 1 of
the Risk Evaluation for Asbestos is based on PCM
measurements.
EPA does not believe the commenter interpreted the
Framework accurately. It clearly encourages (see Section 5.2
of Part 1 of the Risk Evaluation for Asbestos) using upper
95th (UCL) concentration. Based on the totality of
information in the Framework and established TSC A risk
evaluation approaches, EPA will continue to use the 50th
percentile concentration as an estimate of central tendency
exposures and the 95th percentile concentration (and
sometimes the maximum concentration) as an estimate of the
high-end exposures.
2.46 Select one method and apply it uniformly to calculate reduced exposure levels for bystanders and ONUs
SACC,
83
SACC COMMENTS:
• SACC members noted that the various methods used to
estimate ONU exposures with limited data were not
consistent across COUs. The results are unlikely to
accurately represent actual ONU exposures because
most rely on surrogate data from unrelated studies or are
of questionable representativeness and reliability.
SACC noted that in prior chemical DREs reviewed,
when data concerning specific COU ONU exposures are
not available, EPA used the worker central tendency
exposure as the estimate for ONU exposure. That
approach is not used in this Draft RE for Asbestos. The
EPA will consider the formalization of an SOP ONU
exposure assessments. However, as noted in Section 2.3.1.1,
EPA attempts to base exposure point air concentrations on
direct measurements, as gleaned from the systematic review
process. This section also notes that, in cases where such
data are not available, EPA will use similar occupational
data and professional judgment when estimating exposure
concentrations. For Part 1 of the Risk Evaluation for
Asbestos, the available sampling data is primarily for
workers expected to have highest exposures and locations
expected to have highest concentrations, with limited
insights on ONUs.
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various approaches taken in this Draft RE for Asbestos
appear more ad hoc. Multiple SACC members
suggested the need for an SOP for ONU exposure
assessment, specifically establishing a hierarchy of
methods to be applied in future assessments.
• Recommendation 22: Develop an SOP for selection of
ONU exposure point air concentrations when primary
data are limited or unavailable.
PUBLIC COMMENTS:
• The Draft RE for Asbestos uses three methods to
calculate reduced exposure levels for bystanders and
ONUs—midpoint, averaging, and rounding up. Absent
a rigorous selection process, these approaches may be
prone to bias. Rather than the ad-hoc approach in the
Draft RE for Asbestos, EPA should select and use one
method throughout the assessment.
EPA followed the same methodology throughout the
occupational exposure assessment in Part 1 of the Risk
Evaluation for Asbestos, which is reliant on direct
observational data, when available—and use of surrogate
information otherwise. EPA did revise the approach for
estimating ONU exposures for aftermarket automotive
brakes but retained all the ONU exposure estimates.
In Part 1 of the Risk Evaluation for Asbestos, EPA refined
the applied decay factor for aftermarket automotive breaks,
as described in updates to Section 2.3.1.7.5, which is now
based on data collected by NIOSH during its field studies of
this activity. This section of Part 1 of the Risk Evaluation
(Section 2.3.1.7.5) has been updated accordingly.
EPA retained its approach to estimating ONU exposure for
gasket fabrication, which employed a decay factor derived
from Marigold et al. (2006). However, EPA revised Section
2.3.1.4.6 to better explain the approach in the risk evaluation,
and more prominently acknowledge the associated
uncertainties.
2.47 Seek input/increase transparency regarding coordination with OSHA and NIOSH
15,29,
42, 65,
67, 83
PUBLIC COMMENTS:
• EPA should seek OSHA's input and monitoring data for
its risk evaluation of workplace exposures to asbestos.
EPA and OSHA operate under a memorandum of
understanding to coordinate on issues where their
jurisdictions overlap.
• EPA cited OSHA's 1994 RIA for information on
process and exposures for some COUs but not others,
without explanation.
While it may be in the purview of EPA to make
recommendations related to occupational exposures, this
seems to be more appropriately done by NIOSH and
OSHA.
In the 2017 Procedures for Chemical Risk Evaluation Under
the Amended Toxic Substances Control Act (82 FR 33726,
luly 20, 2017), EPA committed to, by codifying, interagency
collaboration to give the public confidence that EPA will
work with other agencies to gain appropriate information on
chemical substances. This is an ongoing deliberative process
and EPA is not obligated to provide descriptions of pre-
decisional and deliberative discussions or consultations with
other federal agencies. In the interest of continuing to have
open and candid discussions with our interagency partners,
EPA is not intending to include the content of those
discussions in the risk evaluation.
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2.48 OSHA regulations
15, 17,
30, 42,
51,57,
65, 73,
83, 92
PUBLIC COMMENTS:
• One commenter stated that OSHA's asbestos
regulations are robust, far reaching, and protective of
workers and ONUs.
• OSHA has acknowledged, however, that asbestos
exposures below its PEL may still pose unreasonable
risks to workers. The PEL is the lowest feasible level
that can be achieved by engineering or work practice
controls in most operations, most of the time.
• OSHA set the PEL at a level that is reliably measurable
and imposed additional work practices and ancillary
provisions for operations regardless of measured fiber
levels (59 FR 40981-82: Aug. 10, 1994). OSHA
conceded that the PEL could result in 6-7 workers per
1,000 developing lung cancer. At the PEL of 0.1 f/cc, a
lifetime risk of death from asbestos-related cancer
would be 3.4 per 1,000 workers and a 20-year exposure
risk would be 2.3 oer 1,000 workers (OSHA (1999); 29
CFR Parts 1910, et al. Occupational Exposure to
Asbestos; Final Rule 1994 pg.40978).
• OSHA standards are by law limited by considerations of
economic and technical feasibility; TSCA is not.
• Another limitation is that the OSHA PEL applies to
chrysotile, amosite, and crocidolite as if they were
equally potent carcinogens. The OSHA PEL of 0.1
fibers/cc might be acceptable for chrysotile but would
not protect workers exposed to crocidolite.
• EPA could foster "across-Agency" action to lower PELs
in ACBM-laden occupational settings. This was a
primary future vision held out by the Lautenberg Act.
• Once commenter requested that if EPA's final risk
determination for this COU reflects the conclusions of
the Draft RE for Asbestos, EPA could exercise its
As noted in comments and EPA responses above, evaluation
of compliance with OSHA's asbestos standard and the
protectiveness of the asbestos PEL is not the purpose of the
risk evaluation. There are important differences between
OSHA standard development process and the risk
evaluations that EPA prepares under TSCA. For instance,
OSHA standards consider technological and economic
feasibility, while a TSCA risk evaluation does not. The
various observations about OSHA's asbestos standard are
acknowledged but they do not have direct bearing on EPA's
risk evaluation for asbestos.
Actions that EPA could take are relevant to the risk
management phase of the overall assessment, which EPA
will commence after the risk evaluation is completed to
address unreasonable risks identified in Part 1 of the Risk
Evaluation for Asbestos.
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discretion under TSCA Section 9(a)(1) and find that
regulation by OSHA would be sufficient to address any
unreasonable risks under the COU in the chlor-alkali
industry.
2.49 Other occupational exposure comments
39, 42,
46,51,
53, 68,
70, 72,
73, 80,
83, 92,
100
PUBLIC COMMENTS:
• Explain how the combination of exposure
concentration, exposure frequency, and exposure
duration used in the risk evaluation (are) representative
of a central tendency and reasonable high-end exposure
scenario.
• One commenter thinks that it is unlikely that EPA
missed other significant potential users in Table 2-2.
• Many of the studies referenced by the EPA include
quantitative or qualitative data that pre-date the 1994
PEL. Not all data reviewed by EPA after 1994 are
robust enough to make accurate risk determinations on
worker or occupational nonuser exposures. In addition,
some of these studies used data and observations that
were outside of the US and therefore may not accurately
portray the exposure to our US worker which has been
controlled by OSHA.
EPA has sufficiently described how central tendency and
high-end exposure estimates are derived based on exposure
concentrations, exposure frequency, and exposure duration
in Section 2.3.1.1 of Part 1 of the Risk Evaluation for
Asbestos.
EPA has previously described its approach to identifying all
reasonably available information in the Scope document as
well as Supplemental Files to the Scope document that
detailed the literature search strategy. Additionally, EPA
followed the process described in the Application of
Systematic Review in TSCA Risk Evaluations document.
Data from the peer-reviewed literature and provided by
industry was subject to data quality evaluation, which is
documented in Supplemental Files to Part 1 of the Risk
Evaluation for Asbestos. EPA is confident that analyses and
conclusions are based up the best available science and
information that was reasonably available to EPA.
3. Consumer Exposure
Charge Question 3:
3.1 Please comment on the estimation methods and assumptions used for consumer/DIY exposure assessment (including bystanders)
in terms of concentration, frequency and duration of exposures; and their use in the risk evaluation. Please include your thoughts on
the reasonableness of the estimated age at start of exposure and duration and frequency of exposure for the consumer (DIY and
bystander) (Section 4.2.3).
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3.2 Please comment on EPA's approach to developing consumer/DIY exposure estimates for aftermarket automotive brakes/linings
(Section 2.3.2.1). Please include your thoughts on the reasonableness of the estimated age at start of exposure and duration and
frequency of exposure for the consumer (DIY and bystander) (Section 4.2.3).
3.3 Please comment on EPA's approach to developing bystander exposure estimates (specifically the use of reduction factors [RFs]
(Sections 2.3.2.1 and 2.3.2.2).
3.4 Please comment on EPA's approach to develop consumer/DIY exposure estimates for other gaskets (UTVs) (Section 2.3.2.2).
3.5 Please comment on EPA's reasonableness of the assumptions used, the uncertainties they introduce, and the resulting confidence
in the consumer exposure estimates (Section 4.3.4).
3.6 Please comment on the methods and assumptions used in approaches for the sensitivity analysis for the consumer (DIY and
bystander) risk estimates for both aftermarket automotive brakes and UTV gaskets (Appendix L).
3.7 Please provide any specific suggestions or recommendations for alternative approaches, estimation methods, assumptions, or
information that should be considered by the Agency for improving the consumer exposure assessment.
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Summary of Comments for Specific Issues Related to
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EPA/OPPT Response
3.1 Aftermarket automotive brakes/linings and UTV gaskets consumer DIY and bystander exposure estimates approach:
General support
SACC,
42
SACC COMMENTS:
• Overall, methods and explanations for estimating DIY
consumer and bystander exposures straightforward and
understandable.
• Overall, assumptions for DIY consumers (including age
at start of exposure and duration of exposure) and
bystanders reasonable for both outside and inside
scenarios.
• SACC was in general agreement that most consumers
are "low-frequency" users of potentially asbestos-
EPA thanks the SACC and public commenters for these
acknowledgements.
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containing consumer products, including UTV gaskets,
and brake shoes.
• SACC was in general agreement that there is no direct
or compelling evidence that asbestos is no longer used
or found in imported after-market products.
PUBLIC COMMENTS:
• Assumptions regarding air exchange rates (facility
versus, garage) are reasonable.
3.2 EPA analysis not necessary
42, 61,
80
PUBLIC COMMENTS:
• One cannot rule out that brakes purchased online by an
individual might contain asbestos. However, <1% of the
brakes sold in the United States in 2013 had asbestos
and >99% of those would have been disc brakes, for
which no exposure during installation or repair occurs.
• Likelihood of serious disease among workplace
employees, bystanders, and persons in the general
population, is remote, particularly given marked
reduction in airborne fiber concentrations over distance
and time.
• The Draft RE for Asbestos lacks important information,
empirical data, and precision; it makes unreasonable
and unreliable assumptions, contains critical
deficiencies, inaccuracies, and uncertainties, and seeks
to address an issue that no longer exists.
• The EPA analysis is not warranted for the post-2020
era. EPA is investing a significant number of hours in
performing calculations about exposure scenarios that
are not remotely plausible to exist in the United States
today.
• EPA assessed chrysotile exposures for the DIY
(consumer) and bystander UTV gasket
repair/replacement scenario based on aggregated
The draft risk evaluation specifically mentions the potential
availability of asbestos containing brakes online for purchase
and installation by DIY consumers (manufactured and sold
outside of the United States). That availability is the basis for
EPA's decision to consider potential exposure to asbestos
from brake replacements (as well as UTV gaskets). EPA
recognizes there are uncertainties associated with
assumptions made for this evaluation, but those assumptions
are based on available information identified and evaluated
as part of EPA's systematic review process.
TSCA requires EPA's risk evaluations determine whether or
not a chemical substance presents an unreasonable risk of
injury to health or the environment under the COUs, with
COUs being defined as "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."
15 U.S.C. 2602(4). As such, EPA, based on reasonably
available information identified and reviewed as part of
EPA's systematic review process, evaluated two COUs
where there is a potential for asbestos exposure to consumers
and bystanders, even if there is a limited number of exposed
individuals.
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exposures resulting from recurring episodic exposures
from active use of chrysotile asbestos related to DIY
brake-related activities. The commenter doubts one
could find an asbestos-containing gasket for a car in the
coming years. Even if one were found, there is no
exposure associated with installing a pre-cut gasket.
Part 1 of the Risk Evaluation for Asbestos bases the
evaluation of exposure to DIY consumers and bystanders
replacing UTV gaskets on the replacement of automobile
gaskets within the engine and not brake related activities.
Exposures resulting from DIY UTV gasket replacement
work is expected to occur more during the removal of an old
gasket (potentially containing asbestos) rather than
installation of a new, pre-cut gasket (also potentially
containing asbestos). However, exposure could continue
during installation due to residual fibers remaining (or re-
entrained during installation) from the removal of the old
gasket.
3.3 EPA does not incorporate the products and processes involved in vehicle repair
32, 74,
79
PUBLIC COMMENTS:
• EPA misstates the current state of scientific
understanding about brakes manufactured with asbestos
in developing the COU.
• The Draft RE for Asbestos suggests a misunderstanding
of vehicle repair, including brake work, and the tools
available and used by vehicle mechanics (e.g, workers
and DIY consumers would not arc grind brake drums).
Thus, EPA uses inaccurate assumptions about exposure
potential that magnifies risk.
EPA discusses the uncertainties of a DIY consumer
performing arc grinding of brake pads/drums within the draft
risk evaluation. While there is uncertainty associated with
arc-grinding activities it is still a potential and foreseeable
activity expected to result in potential exposure to asbestos
and therefore considered in Part 1 of the Risk Evaluation for
Asbestos.
3.4 EPA does not consider aggregate/cumulative exposures
31,51,
86, 88
PUBLIC COMMENTS:
• To fulfill the intent of Congress, EPA must consider
aggregate and cumulative exposures, and not just for
workers.
• EPA estimates 31,857,106 consumer DIYs replace
brake pads but do not include the millions of workers
and consumers exposed to "legacy" asbestos in U.S.
homes, businesses, and schools.
Section 2605(b)(4)(F)(ii) of TSCA requires the EPA, as a
part of the risk evaluation, to describe whether aggregate or
sentinel exposures under the COUs were considered and the
basis for their consideration. The EPA has defined 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)." The EPA defines
sentinel exposure as "the exposure to a single chemical
substance that represents the plausible upper bound of
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• There was no aggregate assessment conducted for
individuals who might be exposed in an occupational
setting as well as a consumer.
• The accumulated data suggest that the excess risk of
death from lung cancer from asbestos exposure is
proportional to cumulative exposure (the duration times
the intensity) and the underlying risk in the absence of
exposure as with lung cancer, the risk [of
mesothelioma] appears to be proportional to the
cumulative exposure to asbestos over a given period.
exposure relative to all other exposures within a broad
category of similar or related exposures (40 CFR § 702.33)."
EPA considered the reasonably available information and
used the best available science to determine whether and
how to consider aggregate or sentinel exposures for
chrysotile asbestos. EPA determined that using the high-end
risk estimate for inhalation risks separately as the basis for
the unreasonable risk determination is a best available
science approach for sentinel exposure.
EPA recognizes it is possible that workers exposed to
chrysotile asbestos at work might also be exposed as
consumers (e.g, by changing asbestos-containing brakes at
home) or may cause unintentional exposure to individuals in
their residence due to take-home exposure from
contaminated clothing or other items. While adding such
exposures could increase risks to the worker, ONU,
consumer, or bystander, which individually exceed the
cancer benchmarks in virtually every scenario evaluated,
these additional pathways are not evaluated together because
EPA did not identify or receive information which could
inform developing such an exposure scenario and does not
have models which could adequately evaluate and address
such combined scenarios.
Aggregate exposures for chrysotile asbestos were not
assessed by routes of exposure in Part 1 of the Risk
Evaluation for Asbestos since only inhalation exposure was
evaluated. Although there is the possibility of dermal
exposures occuring for the chrysotile asbestos COUs, it is
unlikely that dermal exposures would contribute to
mesothelioma and lung cancer. As discussed in the scope
and PF documents, the only known hazard associated with
dermal exposure to asbestos is the formation of warts which
is not associated with mesothelioma or lung cancer.
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In addition, the potential for exposure to legacy uses of
asbestos for any populations or subpopulation, due to
activities such as home or building renovations, as well as
occupational or consumer exposures identified in Part 2 of
the Risk Evaluation for Asbestos, is possible. EPA will
consider these other uses and associated disposal of asbestos
in Part 2, beginning with a draft scope.
3.5 Prioritization of real-world data and use of unpublished data
SACC,
42, 83
SACC COMMENTS:
• Studies that were done in real-world settings for
purposes such as establishing compliance with
regulatory limits should be prioritized over simulations
that were conducted in support of litigation.
• Recommendation 36: Include data from all credible but
unpublished sources in the set of monitored data
discussed and utilized
PUBLIC COMMENTS:
• Exposure scenario assumptions are not based on real-
world observations
• Unpublished studies would offer credible data on DIY
consumer exhaust system gasket repair/replacement.
EPA utilized reasonably available data from published
references in the Draft RE for Asbestos and this Part 1 of the
Risk Evaluation for Asbestos. These data went through
EPA's systematic review process to identify and evaluate the
data considered. These procedures are described in EPA's
Application of Systematic Review in TSCA Risk
Evaluations document.
EPA considered multiple sources of data during its
systematic review process, including published literature,
gray literature, databases, risk assessments, and other
reasonably available information. However, unpublished
data which was not identified or reasonably available during
our searches and which was not provided during public
comments is not included in the risk evaluation.
3.6 EPA's selection of studies to support analysis of aftermarket brake consumer COUs
SACC,
40, 42,
55, 60
SACC COMMENTS:
• Studies used to estimate exposure concentrations for
DIY activitv limited to two studies: Blake et al. (2003)
and Sheehv et al. 0989). The narrowness of the set of
references used in making some of the exposure
estimates reduced confidence in the estimates. In
addition, Blake et al. (2003) was a studv on a
professional auto mechanic, not a DIY consumer.
PUBLIC COMMENTS:
EPA used reasonably available information which was
identified and evaluated as part of EPAs systematic review
process in the Draft RE for Asbestos and Part 1 of the Risk
Evaluation for Asbestos for DIY consumer exposure
activities. The limited data set and representativeness of the
studies to a consumer DIY setting is discussed in the
uncertainties section of the draft risk evaluation. EPA
provided clarifying narratives around the uncertainties of the
studies used in Part 1 of the Risk Evaluation for Asbestos.
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• EPA onlv used one studv, Sheehv et al. 0989), that
provided exposure data for consumer DIY activities.
• EPA should not have relied on occupational studies to
assess consumer DIY exposure; the two groups use
different equipment and procedures.
• Use of the Blake et al. (2003) studv to estimate indoor
and outdoor exposures was not appropriate. It does not
reflect modern-day practices and overestimates
exposure.
• Sources used to support the consumer exposures
approach and methodology for DIY gaskets in UTVs
(Blake et al. (2006; Paustenbach et al. (2006; Liukonen
and Weir (2005) are more relevant to exposures that
occurred 40+ years ago.
• Better sources are available for the handling ND
samples for DIY gasket work.
While the Blake study involved a professional auto mechanic
in an automotive garage, EPA believes the conditions under
which the Blake study was conducted is more representative
of a DIY consumer setting than other studies identified by
EPA. The basis for this is discussed in the draft risk
evaluation and expanded upon in Part 1 of the Risk
Evaluation for Asbestos.
The DIY gasket studies used in the draft risk evaluation were
based on a limited data set found on gasket replacement (and
the absence of data on UTV specific gasket replacement).
This is discussed in the draft risk evaluation and expanded
upon in Part 1 of the Risk Evaluation for Asbestos.
Data from the gasket work which were non-detect were
considered at half the non-detect value in accordance with
EPA practices on utilizing non-detect data when averaging.
3.7 Data gaps regarding asbestos levels in U.S. or imported products
SACC,
74, 80
SACC COMMENTS:
• Recommendation 28: Better describe the efforts made to
ascertain whether asbestos-containing brake shoes and
UTV gaskets are available to U.S. consumers and
consider additional efforts to reduce remaining
uncertainty.
• Paucity of information about the actual availability and
quantity of imported asbestos-containing products
(especially brakes and UTV gaskets) could have been
addressed by the purchase of samples of these items at
various locations in the US and testing the products for
their asbestos content. At a minimum, an estimate of the
upper bound of frequency of asbestos-containing
products and a more realistic estimate of the population
at risk of brake and UTV gasket exposure might have
been obtained.
As stated in the draft risk evaluation, EPA reviewed
published literature, online databases, government and
commercial trade databases. EPA also reviewed company
websites of potential manufacturers, importers, distributors,
retailers, or other users of asbestos. EPA consulted with
USGS and Customs and Border Protection (CBP) staff. EPA
reviewed data from CBP's Automated Commercial
Environment (ACE) system, which provided information for
26 companies that reported the import of asbestos-containing
products between 2016 and 2018. EPA contacted the
importer of record pertaining to gaskets and confirmed that
chrysotile asbestos gaskets are still imported for use in
UTVs. EPA also confirmed that chrysotile brakes and still
imported and installed on vehicles that are then exported.
Based on internet searches performed by EPA staff, the
Agency also believes that consumers can still purchase
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• Recommendation 37: Use an independent market
research group to sample and analyze for asbestos
automotive brake pads, brake shoes and UTV gaskets
coming into the U.S. from overseas.
• Recommendation 33: Confirm and incorporate the latest
information from the USGS on manufactured products
including auto parts containing asbestos that are
imported into the US.
PUBLIC COMMENTS:
• Asbestos imported into the United States currently is
"unknown": in other words, it could very well be
"zero."
• EPA fails to provide any empirical data regarding the
composition of asbestos-containing brakes and/or
clutches.
aftermarket brakes online that are advertised as containing
asbestos.
EPA does not plan to undertake a market survey to obtain,
sample, and analyze automotive brake pads, brake shoes and
UTV gaskets imported into the U.S. for asbestos. The level
of effort and time to develop a full and comprehensive
market survey, obtain products, develop and implement a
sampling and analysis plan, consolidate all findings, and
publish the findings is time prohibitive under the statutory
deadlines for timely completion of the Risk Evaluation for
Asbestos (Part 1 and Part 2). Additionally, it would provide
little to no added benefit to the overall outcome of the risk
evaluation and risk findings. EPA believes there is sufficient
evidence that aftermarket brakes and UTV gaskets
containing chrysotile asbestos continue to be imported into
the US and used by consumers for DIY brake/gasket
replacement activities.
EPA has consulted with the USGS on manufactured products
including auto parts containing asbestos that are imported
into the US. In the USGS's most recent 2020 Mineral
Commodity Survey for Asbestos, the uses of asbestos listed
are identical to the COUs in the chrysotile asbestos risk
evaluation. The USGS states, "In addition to asbestos
minerals, a small, but unknown, quantity of asbestos was
imported within manufactured products, including brake
blocks for use in the oil industry, rubber sheets for gaskets
used to create a chemical containment seal in the production
of titanium dioxide, certain other types of preformed gaskets,
and some vehicle friction products." See
https://pubs.usss.sov/periodicals/mcs2020/mcs2020-
asbestos.odf
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3.8 Data gaps regarding number of exposed consumers
SACC,
51,74,
80
SACC COMMENTS:
• Number of consumers utilizing aftermarket brake shoes
and UTV gaskets containing asbestos is unknown, and it
is unclear what efforts were undertaken to better
ascertain these values.
PUBLIC COMMENTS:
• EPA estimated number of potentially exposed
consumers based on market estimates with no
information on the market share for asbestos containing
products.
• Number of asbestos-containing products unknown, so
number of impacted consumers unknown, requiring
extrapolation from occupational data of uncertain
relevance.
EPA consulted with USGS and Customs and Border
Protection (CBP) staff. EPA reviewed data from CBP's
Automated Commercial Environment (ACE) system, which
provided information for 26 companies that reported the
import of asbestos-containing products between 2016 and
2018. EPA contacted the importer of record pertaining to
gaskets and confirmed that chrysotile asbestos gaskets are
still imported for use in UTVs. EPA also confirmed that
chrysotile brakes and still imported and installed on vehicles
that are then exported. Based on internet searches performed
by EPA staff, the Agency also believes that consumers can
still purchase aftermarket brakes online that are advertised as
containing asbestos. However, due to the limitations to the
data that is reasonably available to EPA there is uncertainty
on the number of consumers who are exposed to aftermarket
brakes and UTV gaskets. This uncertainty is discussed in the
Draft RE for Asbestos and expanded upon in Part 1 of the
Risk Evaluation for Asbestos. Nonetheless, EPA provides an
estimate of the maximum potential number of consumers
involved with DIY activities like brake changes in the Draft
RE for Asbestos and Part 1 of the Risk Evaluation for
Asbestos. The bases for the estimate include manufacturer
recommendations for brake change frequency (per miles
driven) and Department of Transportation estimates of
average miles driven per year. Uncertainties surrounding
these estimates is further discussed in the Part 1 of the Risk
Evaluation for Asbestos
3.9 DIY consumer exposure scenarios not appropriate or not considered
SACC,
31,42,
43, 46,
55,61,
SACC COMMENTS:
• Recommendation 62: Develop and discuss more likelv
exposure scenarios on the use of asbestos-containing
brakes and gaskets by consumer and bystander. For
EPA discusses both the assumptions made when developing
the DIY consumer brake repair/replacement activities and
DIY consumer UTV gasket repair/replacement activities and
the uncertainties associated with each scenario in the draft
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77, 79,
80, 83
example, "shade tree mechanics" who replace the
brakes of their own vehicles often also replace brakes of
cars of family members, friends and neighbors.
• One SACC member noted that drum brakes in other
types of vehicles were not considered and may be more
prevalent than drum brakes in cars today: motorcycles,
farm equipment, snow mobiles. There may be a higher
propensity of owners of those vehicles to do their own
repair work.
• It is possible that significant amounts of chrysotile
asbestos could be in the breathing zone of people
sanding drum brakes.
• For Consumer/DIY exposure estimates for other
(primarily UTV) gaskets, the workforce engaged in
UTV gasket replacement is different from the workforce
engaged in automotive brake repair/replacement, so a
separate COU for is UTV gasket replacement is needed.
PUBLIC COMMENTS:
• The consumer DIY exposure assessment used
unrealistic exposure scenarios that result in exposure
estimates that are not accurate.
• Exposure scenarios used in the Draft RE for Asbestos
represent historical, not current, exposures.
• EPA has not established a basis for assuming that there
will be "known, intended, or reasonably foreseen"
exposures to asbestos from aftermarket automotive
brakes/linings and other vehicle friction products.
• EPA has selected a scenario that assumes use of
aftermarket automotive asbestos-containing brakes;
however, the commenter could not find retailers of such
products.
• EPA assumes consumer purchase and installation of
foreign-made aftermarket parts that contain asbestos
and indicates that <1% of imported brakes from China
risk evaluation. EPA provided additional narrative in the
final Part 1 of the Risk Evaluation for Asbestos to further
clarify assumptions and uncertainties used, including the
uncertainty associated with the number of brake changes
done by an individual DIY consumer, potential shade-tree
mechanics and the potential for over or underestimating
exposures depending on the number of repairs/replacements
done, potential for multiple cars, or fewer miles actually
driven therefore reducing the overall number of brake
repairs/replacements needed in a three year period.
The limited data identified and evaluated through EPA's
systematic review process is prohibitive to expand into other
types of vehicles like motorcycles, farm equipment, or snow
mobiles. While EPA did not identify consumer specific
information on other vehicle types (outside of automobiles
and trucks (light and heavy duty)) and was not provided
information on such other vehicles as part comments, EPA
provided some discussion on the potential exposure resulting
from other vehicles repair/replacement activities. However,
EPA will not be able to extrapolate exposure results from
automobile activities to other vehicle types due to the
absence of data to inform such extrapolations.
EPA considered potential exposure to asbestos from arc
grinding/sanding of brakes in the Draft RE for Asbestos and
carried this into Part 1 of the Risk Evaluation for Asbestos
(chrysotile asbestos).
EPA did evaluate UTV gasket repair/replacement activities
as a separate COU. The studies relied upon for the UTV
gasket repair/replacement activities did involve "gasket"
work although it was on an automobile exhaust system rather
than a UTV exhaust system since EPA did not identify any
UTV specific studies and was not provided any UTV
specific data during comments.
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or Canada allegedly contain asbestos. This is an
unlikely and unsubstantiated scenario.
• If true, brakes sold online would likely be disc brakes.
Installing or removing a new disc brake and its
degradation during use should not pose an exposure
concern.
• Repair of drum brakes is an unlikely exposure scenario.
Consumer DIYs would more likely use/repair disk
brakes.
• Commenter disagrees that asbestos fibers for DIY
mechanics and bystanders outdoors would be similar to
indoors.
EPA provided further clarification on the DIY consumer
scenarios evaluated, bases for selecting these scenarios,
assumptions/uncertainties surrounding the scenarios and
brake types in Part 1 of the Risk Evaluation for Asbestos in
Section 2.3.2.1.
EPA evaluated exposure to DIY consumers in the outdoor
environment based on a study which measured breathing
zone concentrations outdoors. EPA did utilize indoor
exposure data to estimate the outdoor exposure to a
bystander observing the brake repair/replacement work, but
applied a reduction factor of 10 to the indoor values to
account for the higher volume and ventilation rates of an
outdoor environment as well as discussing uncertainties
associated with this decision and reduction factor.
3.10 Consumer scenarios not considered by EPA
• EPA did not develop a scenario that included clutch
work.
• EPA did not consider asbestos from brake pad dust
produced while in use.
• EPA should consider an upper-bound estimate of
exposure that assumes consumers work on multiple
vehicles.
• EPA has concluded with insufficient basis that it need
not evaluate "general population exposures" and other
COUs because such exposures might fall under the
coverage of other environmental statutes administered
by EPA.
• Homeowners are consumers that can be exposed to
asbestos. The commenter cites a physician affidavit that
there are many case reports of mesothelioma in
individuals with brief or low dose 'environmental' or
home exposure. Another expert believes that asbestos
EPA does not intend to evaluate a separate COU for clutch
replacement. EPA did not identify any data on asbestos
exposure from clutch repair/replacement and did not receive
information to consider during comments.
EPA is unclear what the commenter means by "brake pad
dust produced while in use." If the commenter is referring to
exposure to a DIY consumer when brakes are used during
driving, EPA would not expect exposure to a DIY consumer
under this circumstance since the dust would not get inside
the car environment of the car while driving. Similarly, if the
commenter is referring to a scenario involving exposure to a
separate car driver (for example a car driving with its
windows open behind a car with asbestos containing brakes),
this is not an exposure pathway EPA could evaluate due to
lack of data to inform such a scenario and the unrealistic
assumptions and extreme uncertainty associated with the
mechanics of such a scenario.
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exposure in industrialized countries could account for
20% of all mesotheliomas (Goldbers et al. (2010).
As explained in more detail in Section 1.4.4 of the risk
evaluation, EPA believes it is both reasonable and prudent to
tailor TSCA Risk Evaluations when other EPA offices have
expertise and experience to address specific environmental
media, rather than attempt to evaluate and regulate potential
exposures and risks from those media under TSCA. EPA
believes that coordinated action on exposure pathways and
risks addressed by other EPA-administered statutes and
regulatory programs is consistent with statutory text and
legislative history, particularly as they pertain to TSCA's
function as a "gap-filling" statute, and also furthers EPA
aims to efficiently use Agency resources, avoid duplicating
efforts taken pursuant to other Agency programs, and meet
the statutory deadline for completing risk evaluations. EPA
has therefore tailored the scope of the Risk Evaluation for
Asbestos using authorities in TSCA sections 6(b) and
9(b)(1).
Similarly, EPA did not evaluate exposure to "homeowners"
which may receive background exposures to chrysotile
asbestos outside of the DIY consumer user or bystander or
due to environmental exposure in Part 1 of the Risk
Evaluation for Asbestos since background exposures via
ambient air would fall under jurisdiction of the Clean Air
Act.
3.11 DIY consumer exposure levels overestimated
42, 74,
79, 80
PUBLIC COMMENTS:
• Estimated exposure levels are unreasonably high given
EPA's selected exposure scenario. EPA has little
evidence of the current of brake linings manufactured
using chrysotile as a raw material and grossly
overestimates potential exposures.
• There is no evidence that asbestos-containing clutches
are currently being imported or are available in the
EPA's draft risk evaluation and Part 1 of the Risk Evaluation
for Asbestos for chrysotile asbestos use exposure data from
published studies to estimate exposure for both brake
repair/replacement work and UTV exhaust system gasket
repair/replacement work. As a result, the concentrations used
are actual measured values used to estimate potential
exposures.
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aftermarket. Evaluation of automotive clutches should
be removed from its analysis.
• EPA acknowledges that historical asbestos exposures
from clutch repair are lower than comparable brake
repair exposures but treats brakes and clutches the same
for the purposes of its risk evaluation and exposure
analysis.
• The estimated exposure concentration for DIYs and
their bystanders are higher than for occupational vehicle
mechanics, which is nonsensical and unsupported by
any data.
EPA did not evaluate clutch repair/replacement work as an
independent COU in the draft risk evaluation and does not
intend to evaluate such work in Part 1 of the Risk Evaluation
for Asbestos (chrysotile asbestos) due to the absence of data
to inform such a scenario. EPA removed the single reference
to "clutch repair/replacement work" from the consumer
section to eliminate the confusion.
Occupational settings are likely to be larger than DIY
settings and are likely to employ engineering control and
building design to enhance air exchanges (ventilation
system, larger openings, etc) for the work areas. This is to
reduce occupational exposure to volatile chemicals often
present in auto repair facilities.
3.12 Ex
josure frequency/duration assumptions for DIY consumer exposure not supported
SACC,
39, 42,
60, 78,
79, 83
SACC COMMENTS:
• Some SACC members believed that exposure might be
overestimated at older ages because of exposure
frequency assumptions.
• The estimation model of 35,000 miles per three years is
based upon a yearly average number of miles driven and
DIY activity from ages 16-78 years. It might be prudent
to use a distribution as the mileage driven varies
depending upon sex and age.
PUBLIC COMMENTS:
• Exposure duration of 62 years (16-78 years) is not
reasonable and borders on absurd.
• EPA's approach for estimating consumer DIY and
bystander exposure is overly conservative for brake
repair and UTV gasket repair given EPA's implausible
persistent airborne fiber concentrations and DIY activity
frequency and duration.
• The high-end consumer indoor exposure level assumes
3 hours of asbestos disc or drum once every 3 years for
EPA used standard exposure age brackets for cancer over a
lifetime in accordance with EPA policy. However, EPA also
considered the uncertainties associated with assuming a full
78 years (lifetime) where brake work (or gasket work) would
occur and be done by a DIY consumer every three years. To
address this uncertainty, EPA also evaluated exposure from a
single brake repair/replacement activity in a lifetime and still
found unreasonable risk. This evaluation will be pulled into
the body of Part 1 of the Risk Evaluation for Asbestos from
the appendix where it currently resides to address this
comment.
EPA does not believe a distribution of mileage is necessary
based on the finding that a single brake repair/replacement
activity still results in unreasonable risk. That being said,
EPA already discusses the assumptions related to miles
driven and uncertainties associated with such an assumption
in the draft risk evaluation. Further clarification on the
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62 years. Similar assumptions were made for consumer
UTV gasket replacement. These are overly conservative
assumptions.
• EPA's assumption about asbestos fiber removal rate in a
home garage over a 3-year interval is not supported by
scientific principles of air dilution or available measured
data. Actual removal rate would be faster.
uncertainties were provided in Part 1 of the Risk Evaluation
for Asbestos.
EPA provided clarification on its interpretation of the study
data where arc grinding occurred in Part 1 of the Risk
Evaluation for Asbestos. The 3-hours associated with brake
repair/replacement activities is not intended to assume arc
grinding occurs for the entire three hours, and EPA does not
believe the study is based on 3-hours of arc grinding. Rather
arc grinding occurs for a portion of the total brake
repair/replacement activity and sampling time.
EPA's assumption on removal rate is based on limited to no
localized ventilation in a garage through which asbestos
fibers may be removed. It also considers the potential re-
entrainment of fibers due to disturbances from walking or
even driving on garage surfaces where asbestos fibers may
reside.
3.13 Task/activity assumptions for DIY consumer exposure not supported
SACC,
31,40
42, 55,
60, 74,
79, 83
SACC COMMENTS:
• Recommendation 34: Better document current uses bv
consumers of compressed air to clean drum brakes.
PUBLIC COMMENTS:
• EPA uses many unreasonable assumptions for an
activity that has not been performed by many persons in
the last 35 years. It is unlikely a DIY consumer would
use the practices of an occupational mechanic such as
brake filing, sanding, arc grinding, and cleaning with
compressed air.
• Exposure data should more adequately represent the
tasks that would be performed at this time (not
EPA did not identify reasonably available information and
was not provided information describing current consumer
practices related to use/non-use of compressed air to clean
drum brakes. The uncertainty around the use of compressed
air is discussed in the draft risk evaluation and was expanded
upon in the final risk evaluation. Given that DIY videos still
show the use of compressed air and readily available cans of
compressed air (or home air compressors), EPA believes the
use of compressed air is a reasonably available method
which can be used by DIY consumers (even with warnings
that compressed air should not be used) and therefore
evaluates exposure based on such practice.
EPA discusses the uncertainties regarding various
assumptions made in the Part 1 of the Risk Evaluation for
Asbestos. Generally, while arc grinding may not be a
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historically) in a DIY situation. It is unlikely that indoor
arc grinding would be used by DIY consumers.
• It is unlikely that consumer DIYs would sand brake
pads to remove glazing. Glazing occurred more often in
the 1950s-1970s than it has since 1985 due to the better
design of automobiles, the lack of brake drums on
modern cars, and the adoption of disc brakes.
• Consumer DIY use of compressed air in residential
garages not supported.
• Shade-tree mechanics typically work outdoors, so those
exposures would be de minimis (if they occur at all).
common practice for all DIY consumers, DIY videos do
show consumers how to grind brakes and pads. Additionally,
as an example, while modern day cars may not require
grinding/sanding of brakes and pads, those DIY consumers
working on classic cars which no longer have perfect fit
brakes and pads may require grinding/sanding to fit the
modern brake or pad into the classic car brake housing.
Work practices across all shade-tree mechanics is unknown.
While some shade-tree mechanics may work on another
individual's car outdoors, they are just as likely to work on
another individual's car inside the individual's garage (as an
example if it is raining outside when the work is occurring)
and therefore exposures would be similar to the indoor
scenarios evaluated by EPA. Since it is reasonably
foreseeable to assume shade-tree mechanics could work on
multiple cars inside a garage, it is appropriate to consider
exposures from such work based on indoor concentrations.
3.14 DIY consumer exposure underestimated
SACC,
31
SACC COMMENTS:
• Some SACC members believed that exposure might be
underestimated in younger ages and in lower income
groups.
PUBLIC COMMENTS:
• EPA should consider an upper-bound estimate of
exposure that assumes consumers work on multiple
vehicles.
EPA conducted a sensitivity analysis on various ages to
estimate exposures. This analysis is discussed in Section
4.3.7 and Appendix L and includes younger ages. EPA did
not conduct such analysis for various income groups as the
conditions under which brake work would be performed is
relatively independent of income and assumptions made and
uncertainties associated with this risk evaluation are similar
across income brackets.
EPA did not include an upper-bound estimate of exposure
for multiple cars since EPA did not identify or receive data
which could inform how many DIY consumers may work on
multiple vehicles. EPA expanded the discussion on
uncertainties associated with the potential for DIY
consumers working on multiple vehicles (as well as shade-
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tree mechanics) in Part 1 of the Risk Evaluation for
Asbestos.
3.15 Bystander exposure levels overestimated
SACC,
39, 42,
79
SACC COMMENTS:
• There is some concern that estimates of outdoor
bystander exposure were overestimated.
PUBLIC COMMENTS:
• Bystander exposure is overestimated based on evidence
from Donovan et al. (2011) and Williams et al. (2007).
• Egilman and Schilling (2012) would be useful in
estimating bystander exposures.
• EPA assumes that the DIYs and their bystanders spend
time every day, 365 days per year, for 40 to 60 years in
the COU. That is implausible for most, if not all, DIYs
and bystanders. In addition, bystanders are aged "0"
(zero) and onward, and this would appear to be
impossible.
• The estimated exposure concentration for DIYs and
their bystanders are higher than for occupational vehicle
mechanics, which is nonsensical and unsupported by
any data.
• The risk to bystander section of the document is
irrelevant due to near impossibility of exposure.
EPA expanded narrative in the uncertainties section
associated with the outdoor bystander exposure estimates.
EPA acknowledges the use of indoor data, even with a
reduction factor, is a more conservative estimate of
bystander exposure for the outdoor scenario. However, given
the absence of bystander monitoring data in an outdoor
environment during brake repair/replacement activities in a
consumer setting, EPA believes the assumptions made, data
used, and reduction factor provide a reasonable estimate of
bystander exposure.
EPA does not assume DIY consumers and bystanders spend
every day doing the brake repair/replacement work. Brake
work is assumed to occur once every three years in a
residential garage, not every day. However, it is feasible to
assume consumers are in their garages every day (whether
getting in a car to go to work, return home after work, run
errands, etc.). So, while brake work is not done every day,
residual dust is expected to remain in the residential garage
for many years and can be re-entrained repeatedly as a
consumer or bystander drives into or walks across the floor
of the residential garage. In addition, the draft risk evaluation
and Part 1 of the Risk Evaluation for Asbestos defines the
bystander to be of any age which ranges from newborn (in
essence age zero) to elderly. While a newborn that is only a
few days old is not likely to be placed in a garage during
brake or UTV gasket repair/replacement work, exposure is
still possible during motion in and out of the garage where a
newborn may be brought in from the car after running some
errands or an infant doctor appointment and could be
exposed to asbestos if that activity occurs during work or at
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least to residual asbestos (which could be re-entrained) if
work had occurred in the garage at some time.
While it seems unlikely a consumer is exposed to higher
concentrations than an occupational vehicle mechanic, there
are several factors which cause this exposure. Consumers are
assumed to be exposed continuously for a lifetime (rather
than 40 working years 8 hours per day, 5 days per week).
Consumers are not expected to wear PPE or utilize localized
ventilation/engineering controls while workers may wear
PPE and utilize localized ventilation/engineering controls.
DIY consumer practices may vary considerably from worker
practices which could cause higher emissions and therefore
higher exposures.
3.16 Bystander reduction factors not appropriate or require clarification
SACC
SACC COMMENTS:
• One SACC member recommended two papers to better
address reduction factors related to indoor vs. outdoor
exposures: Donovan et al. (2011) (listed in Draft RE for
Asbestos references but does not appear to be utilized)
and Shade and Javiock (1997).
• Reduction factors applied might not closely estimate
outdoor bystander exposures, overestimating that
exposure.
EPA appreciates the recommendations for the papers. While
EPA did not revise the reduction factor used for the
consumer bystander, EPA did expand its discussion on
uncertainties associated with the use of indoor area sampling
concentrations and a reduction factor for an outdoor
bystander scenario. The discussion includes acknowledging
the potential overestimation due to the data used and other
factors which could affect exposure like outdoor volume and
air flows.
3.17 Bystander exposure level underestimated
31, 58
PUBLIC COMMENTS:
• The risk evaluation underestimates asbestos exposure
levels and should rely on real-world data, not simulated
data from two studies.
• The bystander is more actively engaged in the activity
than would be observed in a professional setting and,
therefore, would be assumed to be exposed to the same
EPA utilized reasonably available information which was
identified and reviewed under EPA's systematic review
process to develop and evaluate the specific consumer
scenarios associated with the two consumer COUs evaluated.
EPA defines the bystander, for purposes of this evaluation,
as an individual observing the brake or UTV
repair/replacement activities (not actively involved with such
activity). The commenter is correct that if a bystander was
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level of asbestos fibers as the consumer. Using a RF of
10 underestimates exposure for bystander.
actively involved in a given activity then exposure would be
expected to be higher, however, such exposure would then
be represented by the consumer (user) exposure and
therefore not require a separate analysis.
The use of a reduction factor of 10 is designed to address
some uncertainty associated with using indoor monitoring
data for an outdoor bystander scenario where volumes and
air exchanges could be considerably different (depending on
how close to the work a bystander is observing). However,
the indoor data used was area monitoring obtained at a
defined distance from the work being performed and
therefore would not in itself require adjustments using a
reduction factor to extrapolate from a DIY consumer
exposure to a bystander.
3.18 Sensitivity analysis/quantification of uncertainties
SACC
SACC COMMENTS:
• The methods and assumptions used in the deterministic
sensitivity analysis for consumer and bystander risk
estimates appeared to be well thought out and complete.
The assumptions used for the analysis seemed
reasonable.
• For many of the uncertainties, EPA did not quantify the
direction and magnitude. These uncertainties could be
better documented (e.g, summarized in a table) and
judgments made about the direction and magnitude of
the bias that might result from the assumptions applied.
• To further evaluate true sensitivity, SACC
recommended that EPA use a Monte Carlo simulation
in which known or assumed distributions of values for
the critical drivers or exposure determinants such as:
age at start, age at end, airborne exposure concentration,
hours of exposure per incidence, number of incidences
per year are used individually for both indoor and
EPA did not quantify the direction and magnitude of
uncertainties due to the possibility that the direction could be
either an overestimate or underestimate of exposure
depending on specific factors.
Quantifying the effect of uncertainties on magnitude of an
exposure would require more quantitative evaluation using,
as also suggested by commenters, a Monte Carlo type
simulation. However, for an effective and accurate Monte
Carlo type simulation, EPA would need considerable data in
several areas to derive a true distribution for such a
simulation. While distributions can be estimated or assumed
using certain techniques (triangular, linear, log normal),
these assumptions could increase uncertainties or raise
questions about the representativeness of such distributions
on the actual affected population without supporting data.
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outdoor scenarios and combined with cancer target(s) to
provide an output distribution of cancer risk in which
the percentage of the exposed population that occurred
above and below the target risk were displayed.
• Recommendation 35: Use a Monte Carlo or similar
simulation methodology to identify inputs that most
impact model-estimated cancer risk variability or
uncertainty and use this analysis to focus efforts to
improve risk estimates.
3.19 Text clarifications/other
SACC,
42, 43,
55, 79,
109
SACC COMMENTS:
• EPA references a "specific type" of utility vehicle that
uses an asbestos-containing exhaust system gasket.
Clarify these types of vehicles and better discuss
associated exposures. Recommendation 29: Clarifv the
types of vehicles potentially utilizing asbestos-
containing gaskets and better discuss associated
exposures.
PUBLIC COMMENTS:
• Creating Tables like 2-26 seems unnecessary; airborne
concentrations will be well below the OSHA PEL for
asbestos.
• Text description regarding brake drums on lines 4133
and 4134 of the risk assessment document is not
accurate.
• EPA states that consumers wishing to avoid exposure
should ask retailers if products contain asbestos and
consider not using products that do contain asbestos.
This inappropriately puts the onus for protecting oneself
on the individual, rather than the EPA, the
manufacturer, or the retailer.
• EPA does not discuss the basis for "professional
judgment"-based exposure estimates.
EPA provides clarifying narratives, where appropriate, in the
Part 1 of the Risk Evaluation for Asbestos.
EPA uses the term utility vehicle (UTV) as a general
description to be inclusive of multiple vehicles in use by
DIY consumers. Depending on the manner in which a
particular vehicle is used, a UTV, for purposes of this
evaluation, may include an all-terrain vehicle, a dune buggy,
a snowmobile, or other utility type vehicles. EPA did not
identify or receive UTV specific information which could
better demonstrate which UTV types may or may not utilize
asbestos containing gaskets.
Table 2-26 is not intended to provide a comparison of values
to the OSHA PEL. Rather, Table 2-26 summarizes the data
extracted from the listed studies which was used in the risk
evaluation.
EPA is unable to address the comment regarding brake
drums because the comment does not include any context
regarding "why" any text description regarding brake drums
is not accurate.
While some aspects of certain statements, like the one raised
by this commenter, may seem to shift the burden of avoiding
exposure to a consumer, the intention is to inform consumers
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of potential actions they can take to minimize or avoid
potential exposure to asbestos independent of any risk
management action by EPA to address COUs found to
present unreasonable risk through its risk management and
regulatory process.
3.20 Other
SACC
SACC COMMENT:
• Recommendation 38: If asbestos is found in automotive
brake pad, brake shoe, or UTV gasket market research
samples, then a subsample should be measured for
amount and types asbestos.
EPA does not plan to undertake a market survey to obtain,
sample, and analyze automotive brake pads, brake shoes and
UTV gaskets imported into the U.S. for asbestos. The level
of effort and time to develop a full and comprehensive
market survey, obtain products, develop and implement a
sampling and analysis plan, consolidate all findings, and
publish the findings is time prohibitive under the statutory
deadlines for timely completion of the Risk Evaluation for
Asbestos (Part 1 and Part 2). Additionally, it would provide
little to no added benefit to the overall outcome of the risk
evaluation and risk findings. EPA believes there is sufficient
evidence that aftermarket brakes and UTV gaskets
containing chrysotile asbestos continue to be imported into
the US and used by consumers for DIY brake/gasket
replacement activities.
4. Human Health Hazard/Derivation of the Inhalation Unit Risk (IUR)
Charge Question 4:
4.1 Please comment on EPA's choice of focusing modeling on only lung cancer and mesothelioma.
4.2 Please comment on the appropriateness of the approach to derive the commercial chrysotile-based IURs, including the underlying
assumptions, strengths and weaknesses of the choice of study cohorts used, the key calculation decisions and the modelling used to
derive the IUR (Section 3.2.4).
4.3 Please comment on EPA's approach to characterizing the implications of the assumptions and uncertainties for the confidence
associated with the derivation of the IURs (Section 4.3.5).
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4.2 Please provide any specific suggestions or recommendations for alternative approaches that should be considered by the Agency in
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4.1 Focus on only lung cancer and mesothelioma is too limited
SACC,
31,46,
47, 50,
51,53,
57, 63,
68, 73,
77, 85,
86, 89,
92, 99,
104,
109
SACC COMMENTS:
• SACC recommended adding more justification as to
why only lung cancer and mesothelioma are considered
in this occupational risk assessment.
• Ingestion of asbestos can lead to other types of cancers.
• It also requested justification for the assumption that
lung cancer and mesothelioma effects induced by
exposure to chrysotile asbestos among textile workers
are comparable to lung cancer and mesothelioma effects
induced in users of other asbestos products.
• Health assessment should focus on all health endpoints,
both cancer and non-cancer, and not just mesothelioma
and lung cancer.
• Recommendation 42: Include other cancer sites bevond
lung cancer and mesothelioma as the key cancer
endpoints.
PUBLIC COMMENTS:
• The draft risk evaluation is based solely on the
carcinogenicity endpoints of lung cancer and
mesothelioma. It does not address other types of tumors
(like ovarian, laryngeal cancers, colorectal cancer,
cancers of the stomach, esophagus, and pharynx) and
serious non-cancer lung diseases (like asbestosis and
pleural diseases) known to be caused by asbestos. These
omissions result in a substantial underestimation of risk
• If the EPA lacked quantitative evidence of the risks of
cancers of the larynx and ovary from chrysotile asbestos
(Draft RE for Asbestos 3.2.4.8, In. 5695, 5696), how
Following SACC recommendations, EPA now explicitly
considers other cancers identified by IARC (2012) as being
caused by asbestos exposure. The quantitative derivation of
the IUR has been revised to address additional risks
associated with ovarian and laryngeal cancers by using a
specially derived adjustment factor. See Section 3.2.3.8.1
and Appendix M for details.
EPA has noted in Appendix M of the risk evaluation: The
IARC (2012) also noted that "positive associations have
been observed between exposure to all forms of asbestos and
cancer of the pharynx, stomach, and colorectum." However,
the evidence for an association between these cancers and
asbestos exposure is mixed and IARC did not view it as
sufficient for a determination of causality. The EPA concurs
with the IARC's evaluation and has limited its effort to
estimating the additional risk of ovarian and laryngeal cancer
from exposure to chrysotile asbestos.
EPA did not find sufficient data that showed chrysotile
asbestos effects experienced by textile workers would be
different from the exposure to the chrysotile asbestos in other
asbestos products.
EPA added to the risk evaluation a new section (3.2.2.1) on
non-cancer effects of chrysotile asbestos, but there were no
quantitative non-cancer data appropriate for derivation of
chrysotile asbestos RfC.
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can the EPA state with confidence that the IUR selected
compensates for this risk? Does this compensation lie
solely in the selection of the upper bound IUR?
• The IARC conclusion that ovarian cancer is causally
associated with asbestos has not been supported by peer
reviewed literature and other US agencies.
4.2 Consider the noncancer health endpoints
SACC,
31,47,
63, 105
SACC COMMENTS:
• Recommendation 43: Include asbestosis in the
discussion and analysis of non-cancer endpoints.
PUBLIC COMMENTS:
• Morbidity and mortality risks of non-malignant
respiratory diseases linked to chrysotile such as
pneumoconiosis (asbestosis) and COPD were not
considered.
• Immune activation endpoint must be part of any
asbestos risk assessment since such evidence have been
found in mice.
• Although the noncancer toxicity of chrysotile may be
different from Libby amphibole asbestos, the Draft RE
for Asbestos IUR for chrysotile asbestos may not fully
encompass possible noncancer health risks associated
with chrysotile exposure.
• Several of the COU-related exposures evaluated for
human health risks in Draft RE for Asbestos section 4.2
are at or greater than the POD for non-cancer effects
associated with exposure to Libby amphibole asbestos,
which is 0.026 fibers/cc (U.S. EPA (2014b).
EPA included asbestosis, nonmalignant respiratory disease,
and immune effects in discussion of other non-cancer effects
on chrysotile asbestos in Section 3.2. There is no reference
concentration (RfC) for these non-cancer health effects
specifically for chrysotile asbestos and a new RfC was not
derived in Part 1. Additionally, while asbestosis is a relevant
non-cancer health effect, EPA does not have a precedent of
using mortality data for derivation of a RfC and the only
quantitative data available for chrysotile is data on mortality
from asbestosis.
4.3 Clarify how plural and/or peritoneal mesothelioma were considered
42
PUBLIC COMMENTS:
• When EPA corrects for the actual background incidence
of both pleural and peritoneal mesothelioma, this will
EPA offers clarification on the commenter's assertion. For
example, a peritoneal mesothelioma was observed in North
Carolina cohort. See Section 2.3.4.5. The Balangero, Italy
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affect their derived cancer potency factor. It is
noteworthy that peritoneal mesothelioma has never been
associated with chrysotile only cohorts, and few
persons, if any, over the last 40 years have had
exposures to amphiboles that would have increased their
risk or caused peritoneal mesothelioma. It is unclear to
me where EPA was adding plural and/or peritoneal
mesothelioma in their calculated cancer potency factor.
chrysotile asbestos miners also observed several peritoneal
cases.
4.4 Concerns about the use of mortality rather than incidences
SACC,
25, 42,
45,51,
63, 64,
101
SACC COMMENTS:
• Modeling using cancer mortality outcome rather than
cancer incidence might bias the IUR estimate. In recent
years, survival times for lung and mesothelioma cancers
have been increasing, allowing time for more deaths to
be recorded as owing to other causes (e.g, road
accident), with the result being undercounting of deaths
associated with lung and mesothelioma cancers. The
Committee suggested that background rates that are
currently derived from life table estimates could instead
be derived from incidence data as one way of
accommodating this concern.
• Recommendation 47: Base health outcomes on
incidence rates of lung and mesothelioma cancers rather
than mortality rates.
• The SACC did not agree that using lung cancer
mortality as a proxy for incidence inserts a low level of
uncertainty. Currently, lung cancer screening detects a
large proportion of stage I lung cancer, which are 80%
curable. These workers are candidates for lung cancer
screening because of their exposure and work history.
As suggested by SACC, EPA stopped using lung cancer
mortality as a proxy for incidence and used background
incidence rates in lifetables instead of mortality to address
incidence of cancer explicitly. The revised methodology is
described in Section 3.2.4.4.4.
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Therefore, the SACC expects a large proportion of early
stage lung cancers in these populations.
PUBLIC COMMENTS:
• EPA's risk evaluation is based solely on mortality rates
instead of incidences of cancer associated with exposure
to asbestos. This results in an underestimate of the total
risks associated with exposure to asbestos.
• Based on recent trends toward longer survival for lung
cancer and mesothelioma, by using mortality data, EPA
failing to account for disease incidence. The commenter
recommends that EPA adjust the IUR upward by an
amount that reflects the projected number of missed
cases of cancer and mesothelioma corresponding to the
latest data on survival rates.
• Lung cancer mortality is not a straightforward outcome.
Other potential confounders such as duration of
chrysotile of exposure should be considered.
• Contrary to what is stated in the Draft RE for Asbestos,
survival is improving, and patients with mesothelioma
and their family members should be aware of this. An
increasing number of patients with mesothelioma are
experiencing median survivals of 5-7 years. These are
typically the patients that develop mesothelioma
because of germline mutations of BAP 1 or other genes.
Moreover, the prognosis for peritoneal mesothelioma
has also improved significantly in recent years.
4.5 Concerns about combining lung cancer and mesothelioma for the CPF and IUR
SACC,
42, 47,
65, 95,
109, 70
SACC COMMENTS:
• The approach to combining the IUR estimates from the
two endpoints seemed reasonable to the SACC.
Nevertheless, some SACC members expressed concern
with the approach used in the DRE that uses endpoint
information from distinct cohorts for the two outcomes,
EPA followed the SACC recommendation and based the
chrysotile asbestos IUR solely on data from North Carolina
cohort, rather than combining endpoints from different
cohorts. The revised derivation of the IUR is now the
combined risk of all cancers as recommended by SACC.
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namely combining the lung cancer endpoint from the
SC cohort with the mesothelioma endpoint from the NC
cohort.
PUBLIC COMMENTS:
• Although an IUR for lung cancer and mesothelioma
combined was calculated by IRIS in 1988, the rationale
for combining the individual IURs in the current Draft
RE for Asbestos is not clear. There are reasons to
calculate separate IURs for these two malignancies.
Cells of origin are different (epithelial vs. mesothelial).
Exposure variables are different, with longer latency
and lower dose more characteristic of mesothelioma.
Difference in potency by fiber type is alleged for
mesothelioma but not for lung cancer. Disease behavior
is different, with different clinical presentation. The
only thing these two diseases have in common is that
both are caused by asbestos.
• Other commenters agreed that EPA should not calculate
a single CPF for chrysolite by combining lung cancer
and mesothelioma because they result from different
MOAs with different thresholds. The approach also is
not consistent with the current (U.S. EPA (2005) Cancer
Guidelines.
• One commenter asked if it is appropriate to combine
IUR estimates when one was based on a relative risk
model and one was based on an absolute risk model.
(Draft RE for Asbestos p. 151, Section 3.2.4.6.1)
• If the reason for combining the two IURs is regulatory
simplicity, consideration should be given to weighting
the IUR for lung cancer based on the greater risk of lung
cancer mortality and incidence, and the greater number
of additional risk factors that render subsets of the
population susceptible, compared to mesothelioma.
Although mesothelioma is more specific for asbestos,
lung cancer is the greater public health problem.
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• The commenter agreed with EPA's decision to base the
IUR on lung cancer and mesothelioma, as sufficient
data are not available to develop toxicity values for
other tumors types that have been associated with
asbestos exposures. EPA has not derived a reference
concentration (RfC) for potential non-cancer risks
associated with exposure to chrysotile asbestos. As
evidenced in previous assessments, moreover, lung
cancer and mesothelioma are the most significant risk
drivers when evaluating exposure to asbestos.
4.6 Doses potentially causing mesothelioma are in the vicinity of doses that cause asbestosis
42
PUBLIC COMMENTS:
• If chrysotile could produce mesothelioma (which
remains in dispute), it could do so only at doses that are
in the vicinity of those causing asbestosis (50-400 f/cc-
vear) (Pierce et al. (2016; Churs et al. (1993; Churs
(1988).
The public comment conflicts with accepted models for
cancer and EPA cancer guidelines (U.S. EPA, 2005). In
addition, SACC did not recommend threshold modeling for
cancer.
4.7 Discuss wider context compared to other IRIS IURs
42,51,
57, 76,
97
PUBLIC COMMENTS:
• Currently, IRIS contains two IURs for asbestos. For
comparison, the Draft RE for Asbestos should include
the central tendency estimation of asbestos unit risk and
the upper bound value for each endpoint. The original
IUR was developed by summing up the estimated IURs
for lung cancer and mesothelioma, whereas the current
DRE uses the upper 95% bounds, an approach that
inflates the reported IUR for chrysotile.
• EPA departed from the well-established scientific and
regulatory framework for estimating asbestos risks and
calculates an IUR considerably lower than the long-
standing IUR adopted by IRIS in 1988. This has
significant implications for current and future exposure
limits since the new IUR suggests lower risks.
The central estimates and their upper bound for each cancer
are provided. EPA clarifies that the 1986 general asbestos
IUR is a central estimate of the sum of the two cancer-
specific unit risks, whereas the Libby Amphibole asbestos
and the chrysotile asbestos IUR (as all IURs in EPA) are
upper bound estimates.
EPA reviewed the available literature since adopting the
1988 IUR for general asbestos and derived a new IUR
specifically for chrysotile asbestos.
EPA conducted an intra-agency review as part of the review
process. EPA/OPPT has consulted with EPA epidemiologists
in the IRIS program and elsewhere to ensure methods and
approaches are not contradictory, whilst recognizing
different program objectives and statutory requirements.
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• Some commenters believe that derivation of a new CPF
for chrysotile and this proposal should have been run
through the IRIS process, and the dose-response
assessment should be viewed in the wider context of
other EPA risk assessment efforts. Though the TSCA
proposal was not a formal risk assessment of chrysotile
asbestos for the purposes of IRIS, it plays a similar role
in issuing an updated IUR for chrysotile.
4.8 Justify why a separate IUR for chrysotile asbestos is needed
SACC,
70
SACC COMMENTS:
• The Draft RE for Asbestos does not adequately justify
why a separate IUR for chrysotile asbestos is needed, or
why the Draft RE for Asbestos IUR is better than the
one proposed in the comprehensive 1988 EPA IRIS
Assessment on Asbestos (U.S. EPA (1988b). The 1988
IRIS asbestos IUR is based on a richer set of 14 studies
including the two occupational chrysotile-only studies
used in this assessment. Recommendation 91: Provide
more justification for the development of a chrysotile-
asbestos-specific IUR and include more discussion on
the limitations and relative level of confidence
associated with the proposed IUR.
PUBLIC COMMENTS
• One commenter supported EPA's decision to move
ahead with its evaluation of the identified COUs for
asbestos, while it begins to evaluate legacy uses of
asbestos. They further support EPA's decision to
develop an IUR estimate specifically for chrysotile
asbestos, rather than use EPA's previous estimates for
all types of asbestos. Chrysotile is the only form of
asbestos used to produce diaphragms for the chlor-alkali
industry.
EPA developed an IUR specifically for chrysotile asbestos
because the COUs evaluated for Part 1 of the Risk
Evaluation for Asbestos are for chrysotile asbestos only. In
Part 2 of the Risk Evaluation for Asbestos, EPA will
consider the hazard and risk of cancer and non-cancer for
asbestos fibers that continue to be present in legacy COUs.
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4.9 Textile industry does not represent the exposures of interest
SACC,
34, 39,
41, 42,
60, 64,
68, 76,
79, 90,
103,
106
SACC COMMENTS:
• SACC suggested that there should be a discussion of the
relationship of the airborne asbestos fibers in the textile
environment to the fibers in the airborne dust produced
when replacing brakes. Furthermore, the degradation
from using brakes may result in shorter fibers overall
than those in the original asbestos material, so the risks
from removing old brakes may be different than the risk
in installing new brakes, particularly since installing
new brakes can involve some grinding activities.
• Some SACC members were concerned that the
carcinogenic risk of fibers used in textile manufacturing
may not align with the carcinogenic risk of fibers in
current uses. Recommendation 46: Better iustifv the
assumption that lung cancer and mesothelioma effects
induced by exposure to chrysotile asbestos among
textile workers are comparable to lung cancer and
mesothelioma effects induced in users of other asbestos
products.
PUBLIC COMMENTS:
• EPA relied upon the data from asbestos textile plants,
which historically processed longer chrysotile fibers
compared with other applications, such as in the friction
products, cement, and joint compound manufacturing
industries. The exclusive use of textile industry-based
longer chrysotile fibers in the EPA assessment is not
representative of typical chrysotile fiber lengths used in
general industry. The textile data is largely irrelevant for
AABL where potential exposures are to low levels of
short-fiber chrysotile.
• Vehicle mechanics, whether professional or DIYs and
their bystanders, are not comparable to workers in
asbestos mining and textile milling operations. Textiles
EPA's review of the available data concluded that the best
data on which to base the chrysotile asbestos IUR came from
the textile industry. EPA did not find sufficient data that
showed chrysotile asbestos effects experienced by textile
workers would be different from the effects of exposure to
chrysotile asbestos in other asbestos products. There was no
quantitative exposure data of adequate quality to derive
cancer potency values for chrysotile asbestos based on
studies of automobile mechanics; they were all unsuitable for
use in quantitative risk assessment (see also response to
4.13).
In response to the comment on longer vs shorter fibers, the
Bavesian analvsis bv Hamra et al. (2016) shows that shorter
fibers also have cancer risk. As SACC noted in other
comments (See Section 4.12) "The SACC notes that most
asbestos fibers in textile plants were, in fact, short fibers, i.e.,
less than 5 microns in length."
Chrysotile asbestos is a regulated fiber, which is measured
by PCM units in the absolute majority of cases, so chrysotile
asbestos exposures in textile plants are counted by the same
methods as the chrysotile asbestos in other products.
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use a very different form and amount of chrysotile
asbestos in different work processes and products which
ultimately result in very different exposure
concentrations and potential for individual exposure and
risk of disease.
• The textile workers are an inappropriate cohort to derive
an IUR to be used with workers exposed to asbestos in
gaskets, brakes, and packing because the fibers are
different. Asbestos in gaskets, brakes, and packing are
shorter, encapsulated, and have been soaked in a hard-
phenolic resin. Textile fibers are longer and not
encapsulated. See the Garabrant et al. (2016) meta-
analysis to understand the epidemiology of the cohorts
relevant to gaskets, brakes, and packing.
• By using only the textile industry to derive an IUR for
chrysotile asbestos, EPA discarded much of the
available literature on chrysotile potency including data
relevant to other industries and other environmental
exposures (Garabrant and Pastula (2018; Pierce et al.
(2016; Bernstein et al. (2013; Berman and Crump
(2008a. b; Pierce et al. (2008; Berman (2003; Hodgson
and Darnton (2000).
• The studies chosen to reflect asbestos textile work and
exposure in that industry acceptably. The Draft RE for
Asbestos and calculated IUR is only reflective of
exposures in that industry, not of other asbestos
industries or exposure situations, including
environmental exposures. It is a particular problem for a
Draft RE for Asbestos meant to be applied to given
occupational exposures which are dissimilar.
• It is inappropriate to base the risk evaluation of
aftermarket brakes on studies of long-fiber chrysotile in
textiles, but not consider studies of workers exposed to
short fiber chrysotile in brakes.
• There is a divergence of risk between the textile cohorts
in North and South Carolina and all other
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predominantly chrysotile-exposed cohorts (Hodgson
and Darnton (2010). Per fiber risk of mesothelioma
from chrysotile in textile plants is greater than it is in
the mines likely due to a high proportion of longer
fibers.
• No amount of modeling of epidemiology data can make
up for the serious differences in what is being inhaled
by the textile workers compared to auto mechanics or
millwrights 50 years ago. One must consider the
differences in fiber length, aspect ratio, purity of the
chrysotile, and other factors before grouping them and
considering them equivalent.
• Consider the paper by Korchevskiy et al. (2019) which
can help in understanding of the determinants for
chrysotile cancer potency.
• The chrysotile mining and milling studies clearly show
the risks for lung cancer and mesothelioma in Quebec
miners and millers due to chrysotile (with tremolite). It
seems equally obvious that - for lung cancer but not for
mesothelioma - the chrysotile textile data best
represents chrysotile textile risk. Thus, industrial
process must be considered in any specific assignment
of risk to any other industry which uses - or used -
chrysotile.
• A significant fraction of fibers found in those textile
mills exceeded 20 microns in length, which
mechanistically might or might not possibly be
responsible for some increased risk for lung cancer or
mesothelioma. Berman and Crump (2008a). working
under an EPA funded study, suggested that for
chrysotile, potency may only be present for fibers in the
vicinity of 25-40 microns.
• The need to consider the chemical and physical
properties of chrysotile and other types of asbestos must
be paramount when considering the potential cancer risk
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because majority of chrysotile fibers are embedded in
resin.
4.10 Address heterogeneity between North Carolina and South Carolina textile worker cohorts
SACC,
34, 39,
40, 42,
59, 60,
65, 68,
79, 90,
102,
103,
106,
112
SACC COMMENTS:
• It appeared to the SACC that the NC and SC data sets
are of roughly equal quality, albeit with multiple
sources of heterogeneity as noted in Elliott et al. (2012).
• The SACC concurred that the North Carolina and South
Carolina cohorts had the best exposure data and that this
was a good reason to focus on these cohorts.
• The NC and SC data sets are of about equal quality.
Therefore, SACC recommends that the data for
calculating an IUR for chrysotile asbestos exposures
from the Carolina textile mills be the combined data
from the NC and SC mills, rather than selecting data as
a means of overcoming biases. Such a pooled analysis
can reduce statistical variability. Elliott et al. (2012)
contains a pooled analysis of data from NC and SC for
luns cancer. Berman and Crump (2008a) and Loomis et
al. (2019) contain analyses of the individual level
mesothelioma data from SC and NC, respectively and
results from these analyses could be combined to
evaluate the risk of mesothelioma.
PUBLIC COMMENTS:
• It is inaDDrooriate that Loomis et al. (2010) and Elliott
et al. (2012) combined results across the NC and SC
textile cohorts without addressing the heterogeneity of
pleural cancer and mesothelioma risks across plants.
• Even after adjusting for cumulative exposure (f/ml-
years), the mesothelioma plus pleural cancer rate in
Plant 4 (Marshville) is about 3.5 times higher than the
rate in Plant 3 (Charlotte). This is consistent with a
conclusion that there is a difference in the potency of
SACC did consider all these limitations raised in public
comments to the SACC and this and other SACC
recommendations establish that NC and SC datasets have the
best exposure data and are appropriate to use for chrysotile
asbestos IUR derivation. "The SACC concurred that the NC
and SC cohorts (Lenters et al. (2012; Burdorf and Heederik
(2011) have the best exposure data and that this was a sood
reason to focus on these cohorts." (see 4.13 for more detail
on this SACC recommendation).
The submitted comments provided undisputed information
that UNARCO owned the NC Marshville plant for a period
of time. They also provided evidence that some other plants
from the several that UNARCO owned, did produce amosite
products in those other plants. EPA did not find evidence in
the comments or court depositions that the Marshville plant
was using amosite in its productions and was ever anything
other than a textile plant that used commercial chrysotile
asbestos.
In response to another SACC recommendation, EPA stopped
combining data from NC and SC and based the chrysotile
asbestos IUR on the North Carolina cohort only, as EPA was
not able to locate data to conduct a pooled analysis.
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the fibers between plant 4 and all other NC plants (1, 2,
and 3).
• It is unexplained how EPA regarded the NC plant
exposure data to be "of higher quality than those
utilized in other studies of occupational cohorts exposed
to chrysotile" (page 141 lines 5200-5201), when
Loomis and Dement were completely unaware of the
evidence of amphibole asbestos use in plant 4
(Marshville), failed to recognize the heterogeneity in
pleural cancer and mesothelioma risks among the NC
plants, and failed to recognize that the mesothelioma
risk in the Marshville plant was incompatible with all
other evidence from occupational cohorts exposed to
only chrysotile.
• A small amount of crocidolite suggests a strong effect
on mesothelioma risk (Szeszenia-Dabrowska et al.
(2015). Because of the possibility of confounding by
crocidolite exposure the relationship between
mesothelioma and chrysotile exposure, the NC and SC
textile cohorts should not be used in the Draft RE for
Asbestos.
• Several commenters critically reviewed the strengths
and weaknesses of the NC studies.
• Strengths include reasonably thorough exposure
assessment.
• Limitations include:
- Exposures to asbestos forms other than chrysotile
- Fiber count estimates in plants 3 and 4 are not
reliable.
- Small number of informative deaths
- Concerns about quality of mesothelioma
ascertainment
- Lack of control of smoking
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- Lack of complete occupational history (and length
of employment at textile plant) for the cases of lung
cancer or mesothelioma
• Several commenters pointed to evidence, including
depositions and records Johns Manville record
repository, that amosite and crocidolite products were
manufactured in the Marshville, NC textile plant.
• Based on most recent IARC monograph for asbestos,
there is reason to suspect that some other potential
asbestos types were present in the studies used for the
IUR.
• If EPA wishes to include the NC textile plants in this
risk assessment, it must restrict itself to plants 1
(Davidson, NC) and 2 (Charlotte, NC), where there is
no record of commercial amphibole asbestos use. All
the cases of lung cancer, pleural cancer, and
mesothelioma arose where commercial amphiboles
were used, and no cases arose in plants 1 and 2, where
only chrysotile was used.
• Because roughly 96% of the person-time experience of
the NC textile cohort was derived from plants 3 and 4,
where chrysotile, amosite and crocidolite were used, the
Daoers bv Loomis, Elliott, and Dement (Loomis et al.
(2019; Elliott et al. (2012; Loomis et al. (2012; Dement
et al. (2009; Loomis et al. (2009) are essentially
uninformative on the risks of lung cancer and
mesothelioma among textile workers exposed to only
chrysotile (34-14). Basing the IUR on plants 3 and 4
violated EPA's own rule that when "the available
information does not allow exposures to chrysotile and
amphibole forms to be separated" the data is "judged to
be uninformative with respect to the cancer risks from
exposure to commercial chrysotile and [is] excluded
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from further consideration." EPA's final IUR selection
violated this rule and is not valid by EPA's own rules.
• Workers with less than 30 days of employment
contributed 42% of the total person years of
observation. If the 8 cases of pleural cancer and
mesothelioma arose in workers with <30 days of
employment this would substantially affect the
interpretation of the findings from these papers. Among
short-term workers (<30 days of employment), most
spent the majority of their careers in jobs elsewhere,
about which nothing (including asbestos exposure) was
known.
• As noted by Pierce et al. (2016); Pierce et al. (2008) and
many others, the lifetime cumulative dose is critical to
understand the increased lifetime cancer risk. Tables 2
and 3 from Dement et al. (2009). used for the IUR
derivation, include a "considerable amount of
uncertainty," and some information seems to be
missing. A "key element of Table 3 is the number of
None Detected samples that were observed for each
exposure zone. As noted previously, this can be
important; although for this cohort, it appears that there
was an ample number of samples with detectable
concentrations."
• EPA properly considered studies from the NC and SC
textile cohorts to be of particular importance because
the exposure data and exposure assessment methods are
exceptionally detailed compared to most asbestos
studies. EPA provided an excellent rationale for the
inclusion or exclusion of each cohort carried forward
for the final unit risk determination.
• The Carolina plants can still be considered in a
comprehensive risk assessment including a wider range
of chrysotile (and possibly mixed fiber) industrial
processes if a true estimate of overall risk is sought, but
only for lung cancer.
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• NC textile workers were exposed to mixed fibers
(amphibole and chrysotile) and were not chrysotile-only
cohorts. This makes these cohorts unacceptable for
mesothelioma risk assessment for commercial chrysotile
because low levels of amphibole have a
disproportionate effect on risk.
• The SC textile workers' cohort is not the appropriate
cohort for a chrysotile risk assessment. SC textile
workers were exposed to mixed fibers (amphibole and
chrysotile) and were not chrysotile-only cohorts. The
use of crocidolite asbestos is well documented in the SC
Asbestos Textile plant. Both mesothelioma cases
reported by Dement et al. (1994) worked in the spinning
area of the plant and possibly were exposed to
amphiboles.
• Several commenters critically reviewed the strengths
and weaknesses of the NC studies. Strengths include
reasonably thorough exposure assessment. Limitations
include:
- Exposures to asbestos forms other than chrysotile
- Small number of informative deaths
- Concerns about quality of mesothelioma
ascertainment
- Lack of control of smoking
- Lack of complete occupational history for the cases
of lung cancer or mesothelioma
• The NC Department of Health and Environmental
Control documented an excess of pleural cancer in the
tri-county region of Charleston, SC, over the twenty-
year period from the late 1970s to the late 1990s: 12 of
19 mesothelioma cases diagnosed in 1996-1997 had
worked at the Charleston Naval Shipyard. Thus, the
Charleston Naval Shipyard was responsible for a high
proportion of the mesothelioma cases in the Charleston,
SC, area.
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• Lung burden analyses have shown that members of the
SC textile cohort, thought to be exposed predominantly
to chrysotile, had amphiboles in their lungs. Since
between 28 and 32% of the mesothelioma cases from
the SC Textile plant cohort had excessive amosite
and/or crocidolite in their lungs, this cohort cannot be
regarded as being exposed only to chrysotile.
• The exposure experience of SC textile workers—to the
degree this sample of 64 deceased workers is
representative—is clearly unique and should not be used
to assess risk of lung cancer (or especially,
mesothelioma) in miners, millers, cement workers,
friction product workers, or any other non-textile group
of workers, including those assessed in the current Draft
RE for Asbestos.
• This cohort is not suitable for inclusion for estimation of
risk for mesothelioma, based on the small numbers of
cases and the lack of detail noted.
• If the asbestos-exposed population being studied has a
smoking contribution that is slightly greater than the
comparison population, then the risk of lung cancer
from chrysotile may be overestimated. There is
evidence that this was exactly the case for the analysis
of lung cancer risk for the SC textile cohort.
4.11 Limitation of basing IUR on only two studies
51, 57
PUBLIC COMMENTS:
• The idea of separating out studies that "isolate" the
effects of chrysotile and basing risk estimates on these
studies alone is inherently flawed because of the
uncertainty in the exposure levels in these studies and
the difficulty of using limited data (i.e. the two textile
EPA clarifies that 5 cohorts exposed to commercial
chrysotile asbestos were identified with dose-response
information and considered all of them for deriving the
chrysotile asbestos IUR (NC; SC; Quebec, Canada; Italy;
China)
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studies) to attribute specific potency factors to
individual fibers.
• Because EPA decided on a chrysotile-specific risk
analysis, the Agency screened out all studies for which
exposures were not solely to chrysotile; thus, only two
studies remained by which to calculate the IUR.
Unnecessarily limiting the studies increases uncertainty
for the IUR, because all asbestos studies have
limitations (e.g, how exposure was measured, how
death and disease was tracked), and the smaller the
database, the greater likelihood that particularities of
individual studies will drive risk calculations.
• Reliance on two studies - out of the large number of
epidemiological studies on asbestos - greatly magnifies
uncertainties since different studies have shown
different levels of risk and all studies (including the
North and South Carolina studies) have limitations in
tracking exposure levels, deaths and other inputs that
weaken their reliability standing alone.
• The earlier EPA approach took advantage of the large
number of studies for different fibers and industries by
determining an appropriate weighted average of the
exposure-response relationships found in different
studies, considering observable differences in exposure
circumstances. This is a more defensible approach than
using only two studies from a single industry for dose-
response analysis, as EPA did in the draft risk
evaluation.
4.12 Phase contrast microscopy (PCM) vs. transmission electron microscopy (TEM) for fiber counts impact the IUR
SACC,
31,42,
47, 60
SACC COMMENTS:
• The SACC expressed varying perspectives on fiber
counts. While the comparison of results using PCM vs.
TEM appeared reassuring, suggesting that this is not an
EPA agrees with the SACC regarding the comparison of
results using TEM vs PCM "suggesting that this is not an
important source of uncertainty in the IUR estimation." EPA
disagrees with the public commenter who said "The adoption
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important source of uncertainty in the IUR estimation,
some SACC members were not convinced. Very thin,
short chrysotile fibers are commonly missed by PCM
analyses but are visible by TEM. Many studies are
showing that very thin asbestos fibers (including those
from chrysotile asbestos) may have an important
influence on lung diseases. Also, PCM counts all fibers
longer than 5 microns the same, regardless of their
length. Textile production presumably requires fiber
grades that contain longer fibers, but these longer fibers
may be less relevant to the exposures under
consideration in this Draft RE for Asbestos. The SACC
notes that most asbestos fibers in textile plants were, in
fact, short fibers, i.e., less than 5 microns in length.
• The argument that direct comparison of TEM vs. PCM
is impossible seems reasonable (p. 198, In. 7060-7066).
Would a comparison based on cancer incidence be
possible in order to derive "equivalent" increments of
exposure regarding their impact on incidence?
Uncertainty in converting mass measurements to fiber
counts (p. 198, In. 7068-7077) could be evaluated by
using a range of conversion factors and assessing
impact. The argument that the impact is not different
does not help with this uncertainty, it only implies no
additional bias due to association with the outcome.
However, EPA's argument that exposure uncertainty
should not be a major factor in the NC and SC cohorts
is reassuring.
• EPA should include text providing the pros/cons of
methods of microscopy used to measure fibers.
PUBLIC COMMENTS:
• The Draft RE for Asbestos stated "In developing a
PCM-based IUR in this risk evaluation, several TEM
papers modeling risk of lung cancer were found, but
because there was no TEM-based modeling of
mesothelioma mortality, TEM data could not be used to
by the EPA of a new statistical model to calculate an IUR for
asbestos should be left until a time when the exposure
analyses using TEM have reached a point of practical
scientific and regulatory application" because exposures to
COUs have been measured in PCM units and the only way to
assess risks is to use a PCM-based IUR. When COU
exposure data are measured in TEM units and data are
available to derive a TEM-based IUR for cancer, then EPA
can revisit this issue.
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derive a TEM-based IUR." (p. 30, In. 1229 - 1231). This
is a reasonable assumption at this time.
• EPA properly relied upon epidemiological studies using
PCM directly measured in fibers per cubic centimeter
rather than speculative conversions of historic dust
measurements to calculate unit risk.
• One could perform a TEM-based assessment for lung
cancer and a PCM-based assessment for mesothelioma
and still find a way to combine the two into a single
value.
• Since TEM detects much smaller fibers than PCM, it
would be informative to compare the PCM lung cancer
model with the TEM model.
• EPA does not identify TEM papers mentioned in the
Draft RE for Asbestos or compare the TEM models of
lung cancer to the PCM model of lung cancer, which
EPA used for the risk evaluation. The decision to ignore
the TEM studies seems unjustified because the
"Systematic Review Supplemental File on Data Quality
Evaluation of Human Health Hazard Studies:
Mesothelioma and Lung Cancer Studies" indicates on
pages 10 and 21 that studies using PCM or TEM
analyses are appropriate for use.
• Commenter provided detailed findings that indicate a
similar fit to the risk models of TEM and PCM fiber
counts, but the number of fibers and the range of fiber
sizes counted by TEM is much greater than that of
PCM. The adoption by the EPA of a new statistical
model to calculate an IUR for asbestos should be left
until a time when the exposure analyses using TEM
have reached a point of practical scientific and
regulatory application.
• EPA's risk evaluation relies solely on studies using
PCM measurements of fibers; however, many EPMs
cannot be identified reliably using PCM. Fibers below
the resolution of PCM represent the largest contribution
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to exposure. EPA must evaluate cumulative exposure to
all fiber sizes. Studies show that fibers less than 5mm in
length were highly statistically significant predictors of
lung cancer and asbestosis mortality.
• The long, thin fibers present in the textile facilities from
which EPA selected exposure data may not have been
counted using contemporaneous standard
methodologies for PCM. As such, the exposure data in
the Draft RE for Asbestos is likely to underestimate
actual exposure concentrations experienced by members
of the textile cohorts.
4.13 Additional epidemiologic evidence is available for persons working with and around aftermarket automotive
brakes/linings (AABL)
SACC,
34, 39,
40, 42,
59, 67,
68, 74,
79,
102,
103,
106
SACC COMMENTS:
• The Draft RE for Asbestos focuses on cohorts
occupationally exposed to chrysotile asbestos in the
manufacture of textiles. The SACC concurred that the
NC and SC cohorts (Tenters et al. (2012; Burdorf and
Heederik (2011) have the best exposure data and that
this was a good reason to focus on these cohorts. The
SACC identified other studied occupational populations
that should be given more consideration and possibly
used in the analysis. These included studies from Italy
(Terrante et al. (2020; Pira et al. (2017) China, (Wans et
al. (2013b; Wans et al. (2013a) and Canada (Liddell and
Armstrons (2002; Liddell et al. (1997).
• Some SACC members were not convinced that Table 3-
8 is adequate to support the conclusion that there are no
major differences in risks from chrysotile asbestos
exposures between mining and textiles COUs. The
SACC agreed that given the constraints necessary for
IUR modeling, it was appropriate to focus on the SC
EPA agrees with SACC that NC and SC cohorts have best
exposure data and it is appropriate to focus on these cohorts.
Following SACC and public comments recommendations,
EPA evaluated the quality of studies of auto-mechanics
suggested by SACC and public comments for both
mesothelioma and lung cancer and found deficiencies in
exposure assessment and other aspects of the design of these
studies, (see Supplemental File to this Summary of
Comments and Disposition). Therefore, those studies (and
published meta-analyses based on these studies) are not
appropriate to be included in the risk evaluation of chrysotile
asbestos (See also response to 4.17 with respect to cohort
from Italy. Cohorts from China and Quebec were included in
the evaluation already.)
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and NC cohorts because of their higher quality exposure
data.
• Regardless, the SACC recommended adding discussion
of the exposure assessment and epidemiology studies of
mechanics and the rationale for why they were not used.
Among the COUs considered in the Draft RE for
Asbestos, brake mechanic is the occupation with the
highest number of workers with potential for exposures
from chrysotile-bearing products, specifically workers
who replace old or install new aftermarket brake pads
and shoes. Due to the high friction environment in
vehicle braking, asbestos fibers in used brake material
degrade both chemically and physically. Additional
asbestos exposure occurs in the brake environment
when new brakes are sanded or ground prior to
installation. Several epidemiological studies involving
workers involved in brake replacement have been
conducted. These studies have been cited in several
public comments in the asbestos Draft RE for Asbestos
docket and are summarized in two meta-analysis
publications (Garabrant et al. (2016; Goodman et al.
(2004).
• Many of these studies report no association between
asbestos brake part replacement and mesothelioma and
lung-cancer. For asbestos associated mesothelioma,
these include 12 case-control studies (Asuilar-Madrid et
al. (2010; Rolland et al. (2010; Rake et al. (2009; Welch
et al. (2005; Hessel et al. (2004; Hansen and Meersohn
(2003; Asudo et al. (2000; Teschke et al. (1997;
Woitowitz and Rodelsperser (1994; Spirtas et al. (1985;
Teta et al. (1983; Mcdonald and Mcdonald (1980); and
five cohort studies (Van Den Borre and Deboosere
(2015; Merlo et al. (2010; Gustavsson et al. (1990;
Hansen (1989; Jarvholm and Brisman (1988). For
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asbestos associated lung cancer, these studies include
twelve case-control studies (Corbin et al. (2011; Guida
et al. (2011; Consonni et al. (2010; Macarthur et al.
(2009; Richiardi et al. (2004; Matos et al. (2000;
Swanson et al. (1993; Morabia et al. (1992; Benhamou
et al. (1988; Vineis et al. (1988; Lerchen et al. (1987;
Williams et al. (19771 and two cohort studies (Veslia et
al. (2007; Hrubec et al. (1992V
• SACC members acknowledged the weaknesses of the
brake work epidemiological studies, including poor
exposure assessment and lack of large cohort studies.
Many of these studies do not mention whether cancer
cases or workers performed brake replacement. Also,
none of the studies were specifically designed to study
brake replacement (Kanarek and Anderson (2018;
Teschke (2016; Vermeulen (2016; Welch (2007;
Esilman and Billinss (2005; Lemen (2004). The Draft
RE for Asbestos should review these studies and
consider whether they can be used to evaluate the risk
from chrysotile asbestos exposure stemming from brake
replacement. If appropriate, the data from exposure
assessment and epidemiological studies on workers and
consumers exposed to asbestos from motor vehicle
brake replacement should be included in the weight-of-
evidence narrative for the hazard assessment and risk
determination of lung cancer and mesothelioma.
• Recommendation 48: Justify exclusion of the studies of
mechanics in the IUR estimation.
• Recommendation 49: Include studies of workers and
consumers exposed via brake replacement in the lung
cancer and mesothelioma weight of evidence narratives.
PUBLIC COMMENTS:
• It is inappropriate to use an IUR based on high
exposures to long fiber asbestos fibers used in textile
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manufacturing to estimate risks to workers engaged in
brake and clutch repair who have only low exposures to
short fiber asbestos. There are 33 publications that
provide information on the risks of mesothelioma and
22 publications that provide information on the risks of
lung cancer among motor vehicle mechanics and brake
repair workers (Aguilar-Madrid et al. (2010; Agudo et
al. (2000; Coggon et al. (1995; Finkelstein (1995;
Benhamou et al. (1988; Dubrow and Wegman (1984;
Enterline and McKiever (1963) (see full comment for
full list). In addition, there are two meta-analyses of
these papers: first in 2004, regarding risks of
mesothelioma and lung cancer, Goodman et al. (2004).
and then in 2016, updating the risks of mesothelioma,
Garabrant et al. (2016).
• The above meta-analyses concluded that (a)
employment as a motor vehicle mechanic did not
increase the risk of developing mesothelioma and (b)
although some studies showed a small increase in risk
of lung cancer among motor vehicle mechanics, the data
on balance did not support a conclusion that lung cancer
risk in this occupational group was related to asbestos
exposure. The Draft RE for Asbestos should not ignore
the evidence from epidemiology studies of motor
vehicle mechanics and brake repair workers who were
exposed to low levels of short fiber chrysotile.
• In addition to the literature on motor vehicle mechanics,
there are 13 studies on the mesothelioma and lung
cancer risks in manufacturing of friction products
(brakes, clutches) for motor vehicles, none of which
supports a conclusion that work in brake manufacturing
industries is associated with increased risk of
mesothelioma (Szeszenia-Dabrowska et al. (2015; Clin
et al. (2011; Finkelstein (2010; Pang et al. (1997; Kogan
et al. (1993; Finkelstein (1989; Newhouse and Sullivan
(1989; Mcdonald et al. (1984; Berry andNewhouse
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(1983; Browne and Smither (1983; Ski dm ore and
Dufficv (1983; Mcdonald and Frv (1982; Newhouse et
al. (1982).
• The Draft RE for Asbestos ignores a large body of
relevant epidemiologic evidence on workers working
with and around AABL which show no increased risk of
mesothelioma.
• Multiple Studies Show Vehicle Mechanics and Users of
AABL Have No Increased Risk of Mesothelioma, Lung
Cancer [See original comment for the figure of a list of
studies showing no increased risk of mesothelioma,
studies indicating no increased risk of lung cancer, and
figure showing quality of studies evaluating association
between mesothelioma risk and motor vehicle mechanic
employment],
• Since nearly all of the epidemiology studies of merit
show no increased risk of mesothelioma in the auto
mechanics during that period, it is reasonable to infer
that four fibers/cc-years for chrysotile did not pose a
significant health risk for mechanics who worked from
1940-1975. The obvious caveat to using the experience
of mechanics to estimate the risk to those exposed to
pure chrysotile is that the fibers associated with braking
appear to have lost their biologic activity due to
conversion to forsterite or being filled with phenolic
resins (Bernstein et al. (2018; Bernstein et al. (2003).
4.14 Consider data from epidemiology studies and meta-analyses
jertaining to exposures to asbestos-containing brakes
39, 42,
59, 59,
60, 64,
74, 76,
82, 90,
99, 103
PUBLIC COMMENTS:
• EPA should have relied on an important project that it
funded almost 20 vears aso (Berman and Crump
(2008a; Berman (2003). Also, for assessing the risk of
exposure to phenolic encapsulated materials, like
brakes, packing, and gaskets, EPA should have relied
Following the SACC recommendation, EPA evaluated the
quality of the studies of auto-mechanics for both lung cancer
and mesothelioma and found deficiencies in exposure
assessment and other aspects of the design of these studies,
(see Supplemental File to this Summary of Comments and
Disposition). Therefore, those studies (and published meta-
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upon the meta-analyses studies of auto mechanics by
Garabrant et al. (2016). Goodman et al. (2004). Wong
(2001). and Pierce et al. (2008). They are more relevant
to the Draft RE for Asbestos than the textile workers'
exposure cohorts in the Carolinas (Elliott et al. (2012;
Dement et al. (2011; Loomis et al. (2009).
• EPA should have considered multiple studies of vehicle
mechanics and users of AABL that showed no increased
risk of mesothelioma or lung cancer.
• EPA did not include a discussion of cement
manufacturing cohorts (Albin et al. (1990; Neuberger
and Kundi (1990; Lacquet et al. (1980) or friction
product manufacturing cohorts. Mcdonald et al. (1984)
discussed in other analyses of potency factors stratified
by fiber type.
• Very few, if any, historical asbestos-exposed cohorts
(Bernstein et al. (2013; Berman and Crump (2008a. b;
Hodgson and Darnton (2000) have resulted from those
purely exposed to chrysotile. A mesothelioma mortality
study on an asbestos product manufacturing cohort
(Szeszenia-Dabrowska et al. (2015) demonstrated that
use of even minimal quantities of amphibole asbestos
demonstrably impacted the risk of mesothelioma in a
predominately-chrysotile cohort. Szeszenia-Dabrowska
et al. (2015) reported that mesothelioma occurred only
in the plants where amphibole asbestos had previously
been used during manufacturing.
• Given that this EPA document focuses on brake wear
debris (in no small measure), the cancer potency factor
should be based on the epidemiology studies for brake
mechanics who worked in the 1940-1980 era. An
assessment of these data indicates that the brake wear
debris has no potency for lung cancer or mesothelioma
(Garabrant and Pastula (2018; Garabrant et al. (2016;
Goodman et al. (2004; Wong (2001).
analyses based on these studies) are not appropriate to be
included in Part 1 of the Risk Evaluation for Asbestos.
EPA acknowledges that there are epidemiologic studies of
brake workers, cement cohorts, gas mask workers, and other
groups exposed to chrysotile asbestos and many of those
have supported the basis for the hazard determination that
chrysotile asbestos causes cancers - which EPA accepted as
settled science. However, in EPA's review of these studies
suggested by public comment, none of those provided the
necessary quantitative data required for the IUR derivation
for commercial chrysotile asbestos.
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• The commenter provided a formula that can be used to
predict lung cancer and mesothelioma mortality based
on specific workplace cohort data. They noted that the
total expected mortality was used as a reasonable
surrogate for the age-standardized cohort size, as it was
done by Hodgson and Darnton (2000) for
mesothelioma. They also accounted for a shorter than
lifetime exposure duration by applying the coefficient
Duration/75. It can be demonstrated that this coefficient
yields estimates closely comparable with the (U.S. EPA
(2008) exponential correction factor for shorter-than-life
duration.
• Use epidemiology studies in weight-of-evidence
evaluation of predicted risks and characterization of
associated uncertainties. Epidemiologic findings (of no
risk in auto mechanics) are consistent with and
supported by current knowledge about the composition
of brake wear debris (Anderson et al. (1973). the levels
of exposure during motor vehicle repair (Blake et al.
(2003). and the roles of fiber type, length and width,
durability, and biopersistence, in determining biological
hazards (Bernstein et al. (2005). This knowledge
explains why the compact particles of heat-modified
chrysotile in brake dust in the air of motor vehicle repair
facilities are non-potent carcinogens.
• EPA has eliminated studies that reported no risk by
limiting the evaluations to studies for which the risk of
lung cancer per unit cumulative chrysotile exposure, or
data to calculate that, was available (Draft RE for
Asbestos In. 4973-4975, 4990-4992). "Epidemiologic
observations of forty years (1980-2020) consistently
show that there is no discernable increased risk of
mesothelioma for motor vehicle mechanics. When
adjusted for cigarette smoking, studies of lung cancer in
vehicle mechanics fail to discern an increased risk." For
example, the commenter cited several studies showed
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no association of mesothelioma and the COU. One
study did link mesothelioma to vehicle mechanics.
Several studies that examined lung cancer among
vehicle mechanics found no association.
• EPA should consider all the available studies in their
risk assessment, basing their IUR on a meta-analysis of
all studies that include data on person-years at risk and
cases of mesothelioma.
• An alternative approach would be to use estimates of
risk from various available meta-analyses (e.g, Hodgson
and Darnton (2000); Berman and Crump (2008a.
2008b); Berman (2003)). Whichever dataset is used, the
exposures received by each case of
mesothelioma/pleural cancer should be reported. If this
is not possible for confidentiality and/or other reasons,
the range of exposures and the mean and median
exposures should be reported for the entire dataset, and
for the individuals with mesothelioma/pleural cancer.
This information will allow the reader of the document
to evaluate the range of exposures over which the risks
are extrapolated.
• EPA used only those studies where only commercial
chrysotile was used or where workers were exposed
only to commercial chrysotile; situations where
chrysotile was used in combination with amphibole
asbestos, but available information did not allow
separation of the two were excluded from further
consideration. This decision seems to be somewhat
duplicitous.
• EPA ignored the epidemiological studies of gas mask
workers which have not demonstrated an increased risk
of developing mesothelioma from exposure to
chrysotile asbestos.
• It is unclear why EPA did not include many of the
relevant toxicological and epidemiological studies
regarding asbestos fibers in gaskets, brakes, and
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packing. Given this significant deficiency, there is
virtually no support for the conclusions in this Draft RE
for Asbestos that relies almost exclusively on a new
CPF.
4.15 Consider available inhalation toxicology studies concerning brake dust
39, 42,
60, 74,
103
PUBLIC COMMENTS:
• Toxicological studies also need to be examined and
provide strong support for the conclusions from
epidemiologic studies that exposure to AABL does not
increase the risk of mesothelioma.
• Peer reviewed and published inhalation toxicological
studies concerning brake dust are available, including a
5-day exposure biopersistence study, a 28-day exposure
range-finding study, and a subchronic 90-day exposure
study. Combined with the epidemiology studies of
brake workers, these studies provide substantial
evidence that that working with automotive brakes
manufactured with chrysotile does not increase the risk
of disease and that exposure to brake dust does not
cause disease.
• The chrysotile IUR derived by EPA resulted in it
concluding that certain activities, such as DIY consumer
brake mechanic work, resulted in unreasonable risk.
This conclusion is wildly inconsistent with numerous
experimental and epidemiological studies that have
addressed the same question over the past several
decades. For example, well conducted toxicology
studies have reported no significant inflammatory or
pathological effects in the lung or pleura in animals
exposed to levels of brake dust orders of magnitude
greater than those measured in occupational settings
(Bernstein et al. (2020a, b; Bernstein et al. (2018;
Bernstein et al. (2015; Bernstein et al. (2014).
Regarding studies of auto mechanics, please see response
4.14.
In terms of animal studies, SACC agreed with EPA focus on
epidemiology data and did not find inclusion of additional
toxicology studies warranted.
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4.16 Revisit exclusion of Quebec, Canada chrysotile miner study (Liddell studies)
34, 39,
60, 68,
76
PUBLIC COMMENTS:
• Several commenters provided detailed analysis
defending the Canadian chrysotile miners' data and
encouraging EPA to consider including it.
• Commenter identified four non-occupational studies for
EPA to consider because they provide the most direct
measures of environmental risk available for non-
occupational exposures (mining neighborhood
exposure: Case and Sebastien (1987); Camus et al.
(1998); women living near mines: Camus et al. (2002);
Case et al. (2002)).
• Excluding chrysotile mining and milling studies biased
the IUR in an upward direction. The Quebec cohort
studies must be included if EPA is to provide an
accurate IUR for "chrysotile," especially for
mesothelioma.
• Camus et al. (2002); Camus et al. (1998) compared the
observed number of cases of lung cancer and
mesothelioma in regions of Quebec with primarily
chrysotile asbestos exposure, with the numbers expected
based on the original IUR (U.S. EPA (1988b, 1986).
The EPA model greatly overestimated the numbers of
both cancers; the discrepancy for mesothelioma was
particularly striking. With an estimated chrysotile IUR
close to the original, the current model used in the Draft
RE for Asbestos is unlikely to fare any better.
Liddell studies are supported:
• Case identification is sufficient:
• EPA improperly asserted that Liddell's method of
mesothelioma ascertainment was insufficient because he
mentioned that mesothelioma was rarely seen in Quebec
until 1960. It was rarely seen in Quebec, as was true
everywhere else in the world, because it had not yet
EPA revised evaluation on methods for the Quebec cohort
based on consideration of comments from the public and the
SACC. However, as Berman and Crump (2008) established,
there is an order and half of magnitude in uncertainty about
risk of mesothelioma, because of a sublinear relationship
with exposure concentration. The statistical testing by
Berman and Crump (2008) rejected hypothesis of linearity
(in favor of sublinear relationship) in Quebec data with very
low p-value. In contrast, no such violation of linearity
assumption was observed for South Carolina cohort (Berman
and Crump, 2008). As SACC recommended repeatedly, EPA
evaluation is based on South and North Carolina cohorts.
SACC agreed that quality of Quebec cohort is lower.
However, Table 3-8 shows that range of textile and mine
cohort potencies is similar between mining (including
Quebec) and textile industries.
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been well defined by the medical community. That
criticism applies to every investigation world-wide,
including the NC and SC textile plants that EPA relied
on in the Draft RE for Asbestos.
• EPA dismissed the Quebec miners' cohort on the
grounds that diagnosis of mesothelioma could not be
reliably made (Draft RE for Asbestos p. 147). The
investigators went to great lengths to find every case of
mesothelioma based on best available evidence (Liddell
et al. 0997). Of all the studies relied uoon bv EPA the
Quebec chrysotile miner cohort was the least
susceptible to under ascertainment because instead of
relying on the National Death Index and the ICD; it
actively sought cases through reviewing medical
records, autopsies, pathology reports, biopsies, and
mesothelioma registry records.
• McDonald reported extensive investigations to verify
the diagnoses of lung cancer and mesothelioma among
the Ouebec asbestos miner cohort (Mcdonald et al.
(1971), "investigating and reviewing all certified cases
and searching also for cases not described as such on
the death certificate."
• EPA did not criticize any other study for deficiency in
case identification, even though other studies used
inferior methods for case identification. EPA's rules for
judging study quality were applied unevenly and with
obvious bias against the study of Quebec chrysotile
miners.
• Other studies have not criticized the Quebec chrysotile
miners study for inadequate case ascertainment: United
Kingdom Health and Safetv Executive (Berman and
Crump (2008a, b; Berman (2003; Hodgson and Darnton
(2000), the Health Effects Institute Hei et al. (1991),
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and Iarc (2012b). EPA's criticism is novel and
incorrect.
• EPA should not exclude the Quebec chrysotile asbestos
miner cohort based on an incorrect claim that
mesothelioma deaths are not reported in a way that
allows for derivations of KM.
• EPA's perceived discrepancy in the numbers of dust
measurements is incorrect. EPA appears to have
misread the documents.
• EPA expressed concern about uncertainties in the
conversion of particle counts to fiber counts in the
Quebec chrysotile data. The conversion factor and
correlation between particle counts and fiber counts
were closely correlated (r = 0.84), and the relative risks
for lung cancer were quite similar, regardless of whether
the exposure was expressed in fibers or dust counts
(Mcdonald and Mcdonald (1980). This is a more
meaningful way to assess the validity of different
exposure measurements—how well they predict the
outcome of interest.
• It is common practice to use conversion factors for
comparing samples collected over various time periods
and using disparate analytical methodologies; however,
it does not appear that EPA explored the use or
availability of conversion factors outside of the
referenced cohort publications.
• EPA claimed, "Gibbs and Lachance 0972), reported
that the correlation between midget impinger and
membrane filter counts (0.32) was poor and suggested
that 'no single conversion factor was iustified.'" Gibbs
and Lachance (1974) found that after a logarithmic
transformation of both variables, the correlation was
0.45. For skewed distributions (such as fiber or dust
counts) logarithmic transformation can provide a better
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fit to the relationship with other variables: it is routinely
done. EPA's failure to mention the superior correlation
from the logarithmically transformed variables casts
unmerited criticism on the Quebec data. Moreover, the
conversions from particle counts to fiber counts in the
NC plants (Dement et al. (2009) did not report the
correlation coefficient (either arithmetic or log-
transformed), so there is no valid way to say whether it
was better or worse than the Quebec correlation.
• Exclusion of the Quebec cohort from consideration is
especially striking when the Canadian study remains the
largest amons other chrvsotile cohorts. Both Hodsson
and Darnton (2000) and Berman and Crump (2008a)
included Quebec data in their meta-analysis. Quebec
mining and milling worker data has never been
considered inferior to the Carolina studies from a
general data quality level, despite known limitations
typical for historical asbestos studies. Full exclusion of
the Quebec cohort from consideration in the Draft RE
for Asbestos has negatively affected the statistical
representativeness of the IUR and significantly affected
the validity and applicability of the results.
4.17 Consider chrysotile miners studies from Balangero, Italy
34, 39,
42, 60,
68
PUBLIC COMMENTS:
• The latest updates of the Balansero cohort (Ferrante et
al. (2020; Silvestri et al. (2020) report information on
both mesothelioma incidence and mortality. Thus, this
cohort should have been a candidate for the
mesothelioma component of the IUR.
• EPA stated "The group of Balangero, Italy cohort
studies including Pira et al. (2009) was excluded for
lack of results from models using a continuous measure
of exposure." EPA failed to consider the results from
The latest 2020 reports on the study of the Balangero cohort
were published after the close of the literature search and
were not systematically reviewed, therefore are not included
in the derivation of the IUR.
Previous studies on this cohort (Pira et al., 2009, 2017) were
appropriately considered, as documented in the
Supplemental File to Part 1 of the Risk Evaluation for
Asbestos on data evaluation for epidemiologic studies on
human health hazard, and were not included due to a lack of
results from models using a continuous measure of exposure.
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Pira et al. (2017) and Ferrante et al. (2020), provided
results in relation to continuous measures of exposure
(f/ml-years) at the Balangero, Italy chrysotile mine.
• Pira et al. (2017) have undated the original Balansero
cohort but are not referenced in the Draft RE for
Asbestos, possibly because this reference is missing
from the National Library of Medicine database
(PubMed).
• The Balangero chrysotile miner studies are superior to
the NC and SC textile worker studies for many reasons,
including (a) exposure to only chrysotile (without
amphibole asbestos exposure), (b) original exposure
measurements made by PCM of fiber counts (f/ml)
without any need to convert midget impinger dust
counts (mppcf) to fiber counts, (c) work area- and year-
specific exposure estimates throughout the period of
operation of the mine and mills, and (d) ascertainment
of incident mesothelioma cases and deaths through an
active surveillance system that included reviewing
medical records as well as death certificates.
• There are some little-known facts about the Balangero
cohort in Italv that deserve attention (Pierce et al. (2016;
Pira et al. (2009; Piolatto et al. (1990)
4.18 Consider California Coalinga chrysotile miners and millers
42
PUBLIC COMMENTS:
• There is a real question as to whether chrysotile alone
can cause mesothelioma (certainly at concentrations
below that which causes asbestosis). Studies of the
Calidria mines would be informative for understanding
pure chrysotile as it is extremely pure. The
eDidemiolosv of the miners was uneventful (Ilsren
(2010).
The cited study of Calidria mine lacks exposure information
and therefore, could not be used in Part 1 of the Risk
Evaluation for Asbestos.
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4,19 Consider studies of South African chrysotile miners
34, 39,
59
PUBLIC COMMENTS:
• Studies of South African chrysotile miners reporting no
cases of mesothelioma were ignored by EPA.
• There are a series of studies of mesothelioma in South
Africa that have examined the asbestos fiber types to
which cases were exposed (White et al. (2008; Rees et
al. 0999; Solomons (1984; Cochrane and Webster
(1978; Webster (1973). In 504 histologically proven
cases of mesothelioma in South Africa, no cases were
reported who were exposed to South African chrysotile.
Mesothelioma has not been observed among South
African chrysotile miners despite a workforce of 1,500-
2,000 miners who produced roughly 100,000 tons per
vear of chrysotile from 1975 to 1992 (Rees et al. (2001).
These studies, which provide substantial evidence that
South African chrysotile poses little if any risk of
mesothelioma, should be considered in the Draft RE for
Asbestos.
The cited studies lack exposure information and therefore,
could not be used in Part 1 of the Risk Evaluation for
Asbestos.
4.20 Considered studies of Polish asbestos product manufacturing workers
34
PUBLIC COMMENTS:
• The Draft RE for Asbestos should consider the studies
of Polish asbestos products manufacturing workers in its
evaluation. Szeszenia-Dabrowska et al. (2015) studied
mesothelioma mortality in five categories of
manufacturing of asbestos-containing products
(asbestos cement, textiles, sealing products, friction
products, and waterproofing products). They found no
risk of mesothelioma associated with exposure to
chrysotile from the Soviet Union, but found a clear
association with exposure to crocidolite, even when it
was present as a small proportion of the total asbestos
used.
The cited study lacks sufficient exposure information
(outside of total amount of asbestos per plant) and therefore,
could not be used in Part 1 of the Risk Evaluation for
Asbestos.
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4.21 Chongqing China cohort
42
PUBLIC COMMENTS:
• Commenter is not sure the Chongqing (China) cohort is
worthy of much attention (Courtice et al. (2016; Pierce
et al. (2016; Dens et al. (2012). Some have claimed that
this study has too many shortcomings to be reliable.
EPA documents its consideration of each relevant study
identified according to predefined criteria; the criteria and
evaluation are included in the Supplemental Systematic
Review Files. EPA used the North Carolina cohort for the
derivation of the chrysotile asbestos IUR.
4.22 Concerns with binning approach/estimating fiber size specific cancer potency factors
51,57,
86
PUBLIC COMMENTS:
• The IUR uses a flawed approach similar to the
"binning" framework that the EPA SAB rejected in
2008. During development of the now-abandoned
binning approach in the early 2000s, there was strong
opposition to developing separate potency factors for
chrysotile and other fibers. Commenter cited criticisms
from the SAB, another expert review, and other
publications. The SAB emphasized that "[tjhere is no
compelling scientific basis for estimating different
potency factors for lung cancer by fiber type and
OSWER should take bins that assume this off the table.
Stayner, Dankovic and Lemen have reasoned
convincingly that 'there is absolutely no epidemiologic
or toxicologic evidence to support the argument that
chrysotile asbestos is any less potent than other forms of
asbestos for inducing lung cancer' and that 'chrysotile
appears to be just as potent a lung carcinogen as the
other forms of asbestos.'"
• The IUR determination in the Draft RE for Asbestos
bears similarities to the rejected "binning" approach and
the concerns a commenter expressed in 2008 (provided
as an attachment), which remain valid and relevant
today.
• The potency of asbestos fibers has been addressed
several times by multiple agencies over the last 50 years
In Part 1 of the Risk Evaluation for Asbestos, EPA
documents the rationale for basing the chrysotile-specific
IUR calculations on data from epidemiologic studies with
exposure estimates for chrysotile.
EPA does, however, recognize that legacy uses are
comprised of mixed fiber types and will take this into
consideration in developing Part 2 of the Risk Evaluation for
Asbestos (legacy uses and other fiber types of asbestos).
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and with similar results. The accepted approach is to
assign the same potency to all fibers based on the lack
of convincing support for different potencies. There
may be a differential risk between chrysotile and
amphibole fiber types on a dose-by-dose basis, but
legacy asbestos products were produced using a variety
of fibers and today most are mixed fiber types, even
though chrysotile may be the only fiber in active
commercial use.
4.23 Relative potency of different types of asbestos
42, 40,
51, 76
PUBLIC COMMENTS:
• It has been evident, as evidenced by the different TLVS
for the fiber tvpes in 1979 (American Conference of
Governmental Industrial (1980), that the amohiboles
had very different toxicity from chrysotile fibers
(Bernstein et al. (2020a, b; Hodsson et al. (2005;
Hodsson and Darnton (2000). For the sake of
transparency, the calculations for risk in this document
should be based upon the current CPF for asbestos with
modification by a factor of 100 to reflect the near-
consensus view that chrysotile is at least 100-fold less
Dotent than amosite for mesothelioma (Hodsson et al.
(2005; Hodsson and Darnton (2000). For the vast
majority of cohorts that have been studied, the
predominant factor when evaluating the risks was the
percent of amosite in the product.
• The Draft RE for Asbestos essentially equates chrysotile
and Libby amphibole fibers by their potency (upper
bound IUR = 0.16 for chrysotile and 0.17 for Libby
amphiboles). If the Draft RE for Asbestos chrysotile
IUR, along with the generic asbestos IUR of 0.23, are
not adequately distinguished in table notations, users
may ignore the fact that crocidolite, amosite, and
tremolite have universally been accepted as more
EPA clarified that Libby Amphibole Asbestos IUR and 1986
IUR are not directly comparable to each other or with IUR
for commercial chrysotile derived in this Risk Evaluation.
Footnote 4 states "It is important to mention that the
methodology involved in risk characterization has evolved
over time and the existing EPA IURs for other asbestos types
(U.S. EPA (2014a, 1986) estimated risks of cancer mortality
and did not account for the risk of other cancers, and the
1986 IUR did not adjust for mesothelioma under-
ascertainment."
EPA evaluated quality of cohorts and used only cohorts that
are exposed to commercial chrysotile asbestos. It should be
noted that SACC supported use of these cohorts and did not
suggest use of amphibole-exposed cohorts in this
assessment.
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carcinogenic, particularly for mesothelioma, than
chrysotile. This false sense of equivalent potency might
result in under-protection of workers and populations
exposed to asbestiform amphiboles and zeolites (e.g,
erionite), in different settings such as mining, forestry,
road construction, asbestos abatement, etc.
• EPA's prior 1988 asbestos IUR value of 0.23 f/cc is
based on 14 epidemiologic studies that include
occupational exposure to chrysotile, amosite, and/or
mixed fibers (e.g, chrysotile, amosite, crocidolite) (p.
132). EPA's current chrysotile asbestos IUR value of
0.16 f/cc, which is purportedly based on occupational
exposures to commercial chrysotile, is only 1.4 times
lower than this prior estimate (p. 132). Given the well-
documented differences in cancer potency between
chrysotile and amphibole asbestos, particularly with
respect to mesothelioma, the lack of a more pronounced
difference in unit risk values does not seem reasonable
and is inconsistent with prior risk evaluations. For
example, Hodgson and Darnton (2000) estimated that
the risk differential between chrysotile and two
amphibole fibers was between 1:10 (amosite) and 1:50
(crocidolite) for lung cancer and between 1:100
(amosite) and 1:500 (crocidolite) for mesothelioma. The
authors noted that if the observed "gross differences are
even approximately correct" then "quite small
variations in the fiber mix in the cohorts exposed to
several fiber types could have important effects on the
mesothelioma risk in the cohort" (p. 571).
• Berman (2003): Berman and Crump (2001) found that
the best estimate of the potency for chrysotile was 0.27
times that for amphiboles for lung cancer and 0.0013
times that for amphiboles for mesothelioma. These
authors noted that "the possibility that pure chrysotile is
non-potent for causing mesothelioma cannot be ruled
out by the epidemiology data" (p. 1.4). In a peer
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consultation of this latter work (TJ.S (20031 all 11
panelists unanimously agreed that the available
epidemiology studies provided compelling evidence that
the carcinogenic potency of amphibole fibers was two
orders of magnitude greater than that for chrysotile
fibers with respect to mesothelioma. In an updated
assessment, Berman and CrumD (2008a) found that the
best estimate of the relative potency of chrysotile
ranged from zero to l/200th that of amphibole asbestos
for mesothelioma, and the hypothesis that chrysotile and
amphibole asbestos were equally potent for
mesothelioma risk was strongly rejected by every
metric. The authors concluded: "The analyses presented
herein provide consistently strong evidence that
chrysotile is considerably less potent than amphibole
asbestos in causing mesothelioma" (p. 63-64). More
recently, Garabrant and Pastula (2018) found that the
relative potency for chrysotile: amosite: crocidolite was
1:83:376. A thorough discussion of these prior analyses
and findings and why they differ from the current
assessment should be included in EPA's risk evaluation
for asbestos.
• There is some evidence suggesting that the different
types of asbestos fibers vary in carcinogenic potency. It
appears that the risk of mesothelioma is greater with
exposure to crocidolite than to amosite or chrysotile
alone. Other data indicate that differences in fiber size
distribution may contribute to observed variation in
outcomes.
4.24 Clarify derivation of mesothelioma potency factor
SACC
SACC COMMENTS:
• The SACC questioned the analysis upon which EPA's
preferred mesothelioma potency factor is based. EPA
prefers the estimate of KM from Loomis et al. (2019),
Following this and other SACC recommendations
(Recommendation 56) EPA now uses the variable exposures
Peto model results as reported in Loomis et al. (2019). The
tables in Risk Evaluation were clarified in terms of source of
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which reports a KM of 0.88E-9 (UCL = 1.49E-9) but
which also reports a KM of 2.96E-9 (UCL = 5.87E- 9)
using an alternative analysis that includes only cohort
members alive in 1999. The KM value listed in Draft
RE for Asbestos Table 3-9 as KM = 2.44 E-9 (UCL =
5.04 E-9) has the notation "EPA modeling of Loomis et
al." Earlier in the Draft RE for Asbestos it was stated
that "Because Loomis et al. (2019) reported onlv pleural
cancers before ICD-10, EPA modeled the exposure-
response for mesothelioma using data from 1999
onward when ICD-10 was in use (Table 3-4 suggests
these data are in supplemental table Sib to the original
publication)." SACC did not find a description of this
analysis in the Draft RE for Asbestos or associated
supplements. The analysis by EPA that was used to
provide its preferred KM needs to be better documented
and because the data used are not easily accessed, these
data are provided in a supplement to the Draft RE for
Asbestos. Recommendation 55: Better describe the
derivation of the KM estimate used in the evaluation.
the data. As requested by SACC, the addition of these results
improved the documentation of relevant mesothelioma
results and allowed EPA to better describe the derivation of
the KM estimate used in the evaluation.
4.25 Cancer potency factor range
42
PUBLIC COMMENTS:
• The Draft RE for Asbestos indicates that different
modeling choices and combinations of cancer-specific
unit risks yielded candidate IUR values ranging from
0.08 to 0.33 per f/cc. It seems implausible that EPA
would believe that the plausible range of CPFs would be
that narrow. The span of CPF for a chemical like this
begins at zero and increases with the type of model that
is applied with the data. Most of these models will all
yield reasonable or plausible CPFs, especially for a
generally non-genotoxic carcinogen like chrysotile.
Table 3-12 now shows that the range of candidate IURs is
three-fold and EPA noted that this is a narrow range.
However, this range is based on multiple analyses of two
cohorts that are similar in industry, country, historical time
and were both evaluated as having high quality exposure
assessment. In consideration of this comment, EPA did not
find any revisions or clarifications warranted in Parti of the
Risk Evaluation for Asbestos.
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Usually, the range of plausible CPFs will often span two
orders of magnitude.
4.26 Short chrysotile fibers might pose no risk of cancer
42, 64,
60, 61,
95
PUBLIC COMMENTS:
• There is abundant literature (some supported by the
EPA itself) that shows that cancer risk from asbestos
minerals, including chrysotile, is related to fiber length
and other physical/chemical properties.
• The nature of friction materials and brake wear debris
limits any potential exposure that is assumed to occur
for vehicle mechanics. Brake wear debris contains very
little chrysotile asbestos. The fibers present are the type
most rapidly cleared from the body, are the least potent
type for induction of mesothelioma or lung cancer and
are shorter than the minimum length believed to be
required for induction of mesothelioma or lung cancer.
• Short fiber chrysotile does not cause cancer (including
lung cancer or mesothelioma) at low levels of
exposure, especially to fibers less than 10 microns in
length, and these comprise the majority in fibers
encapsulated in brakes, gaskets and packing. There is
no reason to derive an IUR or CPF for it, particularly
using the LMS model.
• A 2002 AT SDR expert panel addressed the influence of
fiber length on asbestos-related health effects. Overall,
the panelists agreed that "there is a strong weight of
evidence that asbestos and short vitreous fibers shorter
than 5 (am are unlikely to cause cancer in humans"
based on epidemiologic studies, laboratory animal
studies, and in vitro genotoxicity studies, combined
with the lung's ability to clear short fibers. A second
expert panel convened by EPA agreed that the risk
EPA clarifies that the newer Bayesian analysis by Hamra et
al. 2017, which did evaluate the independent effects of short
and long fibers, shows that shorter fibers also have cancer
risk.
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associated with fibers less than 5 |im in length is "very
low and could be zero."
• Brake dust, which is characterized by a short and
altered fiber, has less biological potential than the
longer fibers in the textile industry.
• Lung cancer mortality is not a straightforward outcome.
Other potential confounders such as fiber length should
be considered.
• Longer asbestos fibers are more potent than shorter
asbestos fibers in causing disease, including lung
cancer and mesothelioma. By using textile cohort data
in its Draft RE for Asbestos, EPA likely overstated the
potency associated with chrysotile in other non-
occupational (and occupational) settings.
• Since emphases in the EPA document are COU in
exposures to brake dusts, the chemical and physical
properties of brake dusts containing chrysotile should
be discussed. This information should describe the
percentages of chrysotile included in brake pads, etc.,
and characteristics (including dimensions and amounts
of free fibers) of chrysotile released from brake pads.
Discussion on the impact of sheer stress that reduces
fiber lengths as well as heat modification of fibers that
affects both structural and surface properties of
chrysotile, is necessary.
4.27 Evidence of no safe exposure levels
51,57,
73, 85,
86, 104
PUBLIC COMMENTS:
• Leading health authorities have agreed for years that
asbestos is a human carcinogen and there is
overwhelming consensus in the scientific community
that there is no safe level of exposure.
• Epidemiological studies of low levels of asbestos
exposure have concluded that there are no "safe" doses
of exposure. Since the early 1970s, studies have been
Under TSCA section 6(b)(4)(D), EPA is required to
determine whether a chemical substance presents
unreasonable risks for the conditions of use without
consideration of costs or other non-risk factors. As such,
TSCA does not require EPA to make a finding of whether
there is "no safe level" of asbestos. As stated in Section 5.1
of Part 1 of the Asbestos Risk Evaluation, for the purposes of
making risk determinations for the conditions of use, EPA
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identifying lower and lower asbestos exposure levels
associated with cancer (e.g, Mcdonald et al. (1973);
Mcdonald et al. (1980); Rodelsperger et al. (2001);
Iwatsubo et al. (1998)). Thus, it is unlikely future
studies will find a threshold level of exposure below
which individuals are not at risk of asbestos disease.
The IARC Monograph on Asbestos Volume 14 was first
released in 1977 (IARC (1977). Conclusions in the
monograph have not changed fundamentally since then
(i.e., all forms of asbestos including chrysotile, amosite,
anthophyllite crocidolite and mixed exposures of these
fiber types caused lung cancer as well as mesothelioma
and other cancers). IARC has conducted several update
evaluations since then, the latest in 2009; all reached
similar conclusions.
In 1976, NIOSH concluded that no evidence was found
for a threshold or a safe level of asbestos exposure and
that", (only a ban can assure protection against
carcinogenic effects of asbestos)" (NIOSH, 1996).
In 1998, the WHO International Programme for
Chemical Safety concluded "exposures to chrysotile
asbestos poses increased risks for asbestosis, lung
cancer and mesothelioma in a dose-dependent manner.
No threshold has been identified for carcinogenic risks"
(WHO (1998).
Other regulatory agencies have concluded that risk goes
beyond the worker and recognize there is no safe risk
from exposure to asbestos (e.g, 1977)).
The bottom line is that there is no safe way to use
asbestos, all fibers cause both non-malignant disease
and cancer, and there is no known safe exposure below
which there is no risk for all (Lemen and Landrigan
(2017).
One commenter previously submitted the same
comment (no safe exposure level) to EPA in 2017 on
for the Agency's Scoping Document for asbestos and in
uses 1x10-6 as the benchmark for consumers (e.g, do-it-
yourself mechanics) and bystanders. In addition, consistent
with the 2017 NIOSH guidance, EPA uses 1x10-4 as the
benchmark for individuals in industrial and commercial work
environments subject to Occupational Safety and Health Act
(OSHA) requirements. It is important to note that 1x10-4 is
not a bright line, and EPA used discretion to make risk
determinations based on other considerations including other
risk factors, such as severity of endpoint, reversibility of
effect, or exposure-related considerations.
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2018 for its Problem Formulation document for the
Draft RE for Asbestos.
• Fifty-five countries ban all asbestos uses; the United
States is one of the very few countries that does not.
4.28 Recalculate the potency factors considering Berman and Crump (2008) who used individual [exposure] data
SACC
SACC COMMENT:
• The Draft RE for Asbestos "expresses a general
preference for modelling based on the data from each
individual person in a study, rather than modelling
based on published grouped data." The SACC agreed
with the preference. The distinction between basing an
analysis on individual level data versus grouped data,
however, is somewhat artificial because practically all
analyses of individual data involve some grouping. For
example, all the analyses of the NC and SC textile
cohorts for lung cancer and mesothelioma utilized
Poisson regression, which involved grouping the data
into bins defined by various characteristics including
exposure. Having access to the individual data allows
the average exposure in a group to be estimated
accurately. If only a range originally is reported, the
EPA uses the highest exposure reported to represent the
group in the highest exposure bin (Draft RE for
Asbestos In. 5079). EPA used this approach in modeling
grouped lung cancer data from both the SC and NC
studies. However, this approach typically will
overestimate exposure.
• Berman and Crump (2008a) report an analvsis of the
lung cancer data from the SC textile cohort based on
individual level data which uses the same exposure
groupings as EPA's analysis (Draft RE for Asbestos p.
294 and Table 3-3). Berman and Crumo (2008a) used
the individual exposure data to calculate an exact
Following this and other SACC recommendation, EPA
changed the modeling of the lung cancer data, by allowing
alpha to be estimated (as well as equal to one). EPA also
changed (where it was able to obtain data) the midpoint of
the exposure groups to the mean. EPA also note that
Dublished simulation results (Richardson and Loomis (2004)
show that midpoint and mean are, in general, both
reasonable.
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average exposure in each group (185.1 f/ml for the
highest exposure group compared with the 410 f/ml
assumed in the EPA analysis). Moreover, the EPA
analysis assumed the relative risk model (In. 5025)
where the background parameter a is equal to 1, which
implies that the background lung cancer rate in the SC
textile mill was equal to that in the general population.
Berman and Crump (2008a), however, found that the
hypothesis a = 1 could be rejected (p = 0.008), with the
best estimate being a = 1.35, which implies that the SC
cohort had a higher rate of background lung cancer than
the general population.
• The Draft RE for Asbestos similarly overestimates
exposure in the highest exposure srouo in the Loomis et
al. (2009) analvsis of the NC textile cohort luns cancer
data, which probably accounts for the Draft RE for
Asbestos estimate of KL based on grouped data being
the smallest of the four KL estimates reported in Table
3-4. The EPA analyses of the grouped data reported in
both Table 3-3 and Table 3-4 should be redone to take
these problems into account.
• Recommendation 57: Recalculate the ootencv factors
considering previous analyses performed using
individual [exposure] data, estimates of the background
parameter a, and methods that do not overestimate
exposures in the highest exposure group.
4.29 Justify choice of or replace AIC model-selection criterion
SACC,
63
SACC COMMENTS:
• Recommendation 52: Replace the AIC model-selection
criterion with a criterion that puts more weight on the
low-exposure range of the data. Such as detailed in
Atkinson and Riani (2000). Akaike Information Criteria
(AIC) do not address how well the linear and
exponential models fit the parts of the dose response
In other SACC recommendations (Recommendation 50),
SACC recommended using linear model for lung cancer to
better assess dose response at the low end of the exposure
range and EPA followed that recommendation. EPA
provided all modeling results (linear and exponential fit for
lung cancer data) for comparison in Table 3-12 of Part 1 of
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relationship, especially at the low end of the exposure
range. (SACC-115) Recommendation 102: Provide
more details and further justify use of the AIC to choose
among potential dose response models, and how
different models change the estimated point of
departure.
• The Draft RE for Asbestos justifies use of the
exponential model over the linear model because the
exponential model provides a better fit to both the SC
and NC lung cancer data, as determined by model AIC
values, which measures fit over the entire exposure
range. However, when computing an IUR, the primary
interest is in the risk at low exposures. A better
approach might be to emphasize how well the models fit
the lower dose data. This could possibly be
accomplished by comparing AICs using only data from
lower exposures.
PUBLIC COMMENTS:
• Commenter provided detailed analysis of the Elliott et
al. (2012) assessment of model fit using AIC that EPA
used as justification for an exponential model.
Commenter also argued that it did not appear that EPA
has chosen the best model using all available data for
lung cancer potency estimates using the SC cohort.
• EPA's choice of a non-linear model is based solely on
statistical "curve fitting;" the Draft RE for Asbestos
does not cite any mechanistic or other biological basis
(e.g, MO A) for preferring an exponential model, which
is a prerequisite for overcoming the presumption of
linearity under (U.S. EPA (2005) Cancer Guidelines.
Others who have examined the SC and NC data have
concluded that "the best model for lung cancer was
linear on a multiplicative scale with the best data fit
obtained when the threshold was set at zero"
(Markowitz (2015). Equally important, EPA only
performs its "curve fitting" analysis on two
the Risk Evaluation for Asbestos, illustrating changes in
PODs and risks.
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epidemiology studies. Without considering the much
larger body of available data, EPA "makes a large leap
of faith" in concluding that the exponential model is
broadly applicable to asbestos carcinogenicity.
• Simply the "best statistical fit" or the lowest AIC is an
inadequate reason to select an exponential model over
the low-dose linear model to estimate the IUR. (57, 51)
Given the large uncertainties in individual exposure
measurement and disease tracking, the 'good fit' of the
exponential model for the SC and NC cohorts could
happen bv chance. The commenter quoted Silverstein et
al. (2009) as savins that "Ttlrvins to turn fundamentally
unreliable data into valid and reliable output is
statistical alchemy, no matter how sophisticated and
complex the mathematical models." The imprecision in
the exposure levels "does not provide a strong basis for
this type of 'curve fitting' modeling" (Commenter #57
as cited in comment 51-9).
4.30 Fit and compare linear and exponential model
SACC,
32, 34,
39, 40,
41, 42,
47,51,
57, 60,
62, 63,
65, 86,
90, 95
SACC COMMENTS:
• Recommendation 50: Compare the estimated IUR
derived from the linear model fit to the IUR estimated
from the exponential model fit. Fit the two competing
models, the linear model and exponential model, to a
low dose subset of the data and comparing results. See
Elliott et al. (2012) pooled analvsis for luns cancer.
Berman and CrumD (2008a) and Loomis et al. (2019)
could be combined to evaluate the risk of mesothelioma.
• The EPA Cancer Guidelines (U.S. EPA (2005) specify
that the choice of the approach for extrapolation of risk
to low doses be based on an understanding of the MOA
by which a substance causes cancer. The Draft RE for
Asbestos should link the section describing what is
Following SACC recommendation, EPA used linear model
fit from North Carolina cohort in its chrysotile asbestos IUR
derivation based on NC cohort. EPA provided all modeling
results (linear and exponential fit for lung cancer data) for
comparison in Table 3-12 illustrating changes in PODs and
risks. EPA was not able to obtain data for pooled analysis of
mesothelioma data.
EPA does not agree with commenters proposing relative risk
model for mesothelioma, because the SACC recommended
that EPA use absolute risk model and EPA followed EPA
cancer guidelines in its low-dose extrapolation, as indicated
by expanded MOA discussion (SACC recommendation 94),
which indicated appropriateness of linear extrapolation.
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known about the MOA of asbestos in causing cancer
with the selection of a linear extrapolation procedure as
required in the Cancer Guidelines. At least one SACC
member believed that there was sufficient information
to justify assessing risk from chrysotile asbestos using a
threshold procedure, incorporating the results of
numerous worker studies that have reported no
increased risk for lung cancer and mesothelioma.
PUBLIC COMMENTS:
• Compare the linear and exponential model IURs to
demonstrate the importance of model selection for the
textile worker studies.
• It would be useful to further understand why EPA used
an absolute risk model for mesothelioma and a relative
risk model for lung cancer. These are likely rational
choices, but a deeper look into this statistical aspect
would be useful.
• The Draft RE for Asbestos states that "Limiting the
results in Table 3-6 to lung cancer results based on the
better fitting exponential models yielded four
combinations that were essentially equivalent in terms
of statistical fit and study quality (Table 3-7)" (p. 154,
In. 5661-5663). It is not clear why these models are
"essentially equivalent." This needs to be better
explained to be more apparent to the reader.
• EPA should base its risk calculations for mesothelioma
on a relative risk model. EPA uses a relative risk model
for lung cancer (e.g, Draft RE for Asbestos p. 150 In.
5569-5570), wherein it implicitly agrees that there is no
methodological argument in favor of an absolute risk
model over a relative risk model for asbestos-related
malignancies. EPA provided no justification for its
reliance on an absolute risk model for mesothelioma
when a relative risk model was deemed appropriate for
lung cancer.
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• By using an absolute risk model for mesothelioma, EPA
was unable to benchmark their findings against the body
of epidemiological literature for chrysotile-exposed
populations, including users of end-products, such as
brakes and gaskets.
• Accumulating science indicates that the LNT model is
inappropriate for evaluating cancer risk at low levels of
exposure. This is particularly true in scenarios such as
workers using AABL, where a large body of
epidemiologic evidence provides direct information
related to risk.
• EPA's use of an LNT model is not supported by
toxicology or mechanistic evidence, which indicate a
threshold for carcinogenic effects of chrysotile. The
linear-no-threshold model likely considerably
overestimates the cancer potency of chrysotile asbestos.
Regarding DNA-reactive substances, recent scientific
evidence indicates that the small increase in DNA
damage that might occur from very low exposures, in
addition to the already high levels of endogenous DNA
damage, should not overwhelm DNA repair capacities
(Cardarelli and Ulsh (2018). This indicates a threshold
even for DNA-reactive substances. Evidence is
generally supportive of a MOA involving chronic
inflammation and cellular toxicity and repair that leads
to the generation of reactive oxygen species and DNA
damage, rather than direct interaction with DNA
(Huang et al. (2011). This threshold mechanism can
only occur at exposure concentrations high enough to
overwhelm cellular defense mechanisms.
• Bogen (2019) and Cox (2019) make a persuasive
biological case for the existence of a threshold in
inflammation-mediated carcinogenesis, which is widely
believed to be the mechanism by which asbestos causes
cancer (e.g. Iarc (2012b)).
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• Given chrysotile's lack of genotoxicity and robust
epidemiological data, the LMS model is almost
certainly not appropriate. Many toxicologists have
argued that safe levels of exposure can be derived by
the classic safety factor approach applied to a genuine
or apparent human NOEL (f/cc-year).
• EPA should be cautious in applying any variation of the
LMS model to short-fiber chrysotile. There is strong
evidence that short-fiber chrysotile is a threshold
carcinogen.
• The LNT model has previously been shown to
substantially overestimate the number of cases of
mesothelioma expected within a population (Camus et
al. (2002). especially at low cumulative exposure levels.
Commenter cited additional reasons for the limited
utility of the LNT approach, including consideration of
asbestos pathology and weight of the epidemiological
evidence.
• Chrysotile is almost certainly a threshold carcinogen so
the benchmark dose method should probably have been
used to identify an acceptable dose.
• Pierce et al. (2016) recently derived "best estimate"
chrysotile NOAELs of 208-415 f/cc-years for
mesothelioma and 89-168 f/cc-years for lung cancer
that can be applied as thresholds in chrysotile cancer
risk evaluations. EPA did not discuss Pierce et al.
(2016) or acknowledge a possible threshold mode of
action for chrysotile. The assumption of absolute risk
for mesothelioma does not consider reports of no-
observed-effects threshold for exposure to chrysotile
asbestos (Pierce et al. (2016).
• By using an LNT model to extrapolate risk to doses
below the available exposure-response data for the two
textile industry studies, the estimated chrysotile IUR
will overestimate risk (Barlow et al. (2017). The risk
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estimates are not supported by mechanistic, toxicologic,
or epidemiologic evidence.
• The approach taken by EPA in the Draft RE for
Asbestos is more akin to the approach taken by
plaintiffs' counsel in asbestos personal injury cases in
that it uses an absolute risk model that is contrary to the
current best available science.
• In selecting an exponential risk model for asbestos and
lung cancer, the EPA deviates from the linear model
that it has used up to the present time, and which has
been long relied upon by scientists, government
agencies, and other organizations. Analyses of the data
from the two textile cohort studies (used for the new
IUR) have shown good fit with a linear model. Given
the other uncertainties inherent in the Draft RE for
Asbestos, the difference in fit does not warrant
abandonment of the linear model by EPA. These
uncertainties include a difference in the strength of the
association between cumulative asbestos dose and lung
cancer risk between the two textile cohorts, with the
association being stronger for the SC cohort.
• The use of an "exponential" rather than a "linear model"
to determine cancer potency is not protective.
Commenter cited U.S. EPA (2005) Cancer Guidelines
as emphasizing the high level of evidence necessary to
depart from the presumption of linearity for
carcinogens.
• The selection of an upper-bound IUR (combined for
lung cancer and malignant mesothelioma) does not
compensate for the underestimation of risk introduced
by omission of amphibole fibers, cancers of the larynx
and ovary, and nonmalignant asbestos-related disease
from the Draft RE for Asbestos. Continued use of the
more protective linear model to evaluate risk for
asbestos is necessary.
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• The Draft RE for Asbestos applies an exponential
model that agencies have never used before and has
been disfavored by the consensus groups of asbestos
scientists.
• The linear lung cancer relative risk model from the Hein
et al. (2007) study is a better choice as this model: (1)
includes the entire SC study cohort, (2) is based a model
whose parameters were specifically chosen using the
full study data, (3) is supported by a body of literature
concerning quantitative risk assessment using
longitudinal epidemiological data, and (4) is consistent
with prior EPA risk assessment practice.
• A specific numerical threshold value does not exist, or
if it does exist, cannot be reliably determined. The
asbestos exposure threshold concept for mesothelioma
is scientifically ambiguous. First, selecting a numerical
threshold necessarily involves a value judgement
concerning an acceptable level of risk. Second, even if
an acceptable risk level has been determined, estimation
of the corresponding exposure typically requires
extrapolation of a statistical risk model far-below
observable data.
• In the Draft RE for Asbestos discussion of the time
relationship of lung cancer risk and asbestos exposure,
the data can be interpreted in terms of a multistage
model of cancer in which asbestos appears to act at a
single late stage. The continued high risk following
cessation of exposure results from the continued
presence of asbestos in the lungs. This model is
compatible with a linear dose-response relationship.
• EPA's use of a default linear approach should be
explicitly acknowledged in the risk evaluation,
including a description of the uncertainties and
conservatism associated with this approach.
• The high end of the range for the linear model runs is an
IUR 0.33 per f/cc (SC cohort) while the lower end of
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the range for the exponential runs is an IUR of 0.08 per
f/cc (NC cohort). This four-fold difference illustrates
the implications of model choice for the protectiveness
of the IUR and the risk levels EPA uses for its
determinations of unreasonable risk. EPA should revise
its IUR derivation to use the protective linear low-dose
model consistent with EPA's cancer risk assessment
guidelines.
4.31 Consideration of background mesothelioma rates and basis of IUR concept of excess risk
SACC,
29, 34,
39, 40,
42, 56,
59, 60,
62, 71,
79,
102,
103
SACC COMMENTS:
• Even if all mesotheliomas cases with no known asbestos
exposure were caused by environmental asbestos
exposure rAmerican Cancer Society, Mark and Yokoi
(1991), Strauchen (2011)1, this would still imolv a
background of mesothelioma that possibly should be
accounted for in EPA's assessment of risk of
mesothelioma.
• Therapeutic radiation for lymphoma has been reported
to cause mesothelioma (Chans et al. (2017; Teta et al.
(2007), and several studies have discussed
mesothelioma cases with no known exposure to
asbestos (e.s, Spirtas et al. (1994); McDonald and
McDonald (1994); Mcdonald and Mcdonald (1980);
Mcdonald (1985); Moolsavkar et al. (2009); Price and
Ware (2009. 20041; Roaali (20071; Walker et al.
(198311.
• The Peto mesothelioma model used in the calculation of
the IUR does not accommodate the possibility of a non-
zero background for mesothelioma. (SACC-119)
Berman and CrumD (2008a) applied an expanded Peto
mesothelioma model to the SC mesothelioma data that
accounted for variable exposures and reverted to the
original Peto model when exposure was determined to
EPA followed SACC recommendation by accounting for
variable exposure for North Carolina cohort. The new results
are presented in Table 3-4. Use of Peto model (without
background exposure term) for mesothelioma modeling is a
longstanding Agency framework (U.S. EPA 1986; 2014). In
addition, use of variable exposure obviates EPA modeling of
NC mesothelioma data as variable exposure modeling are
presented in Loomis et al. (2019).
SACC agreed with EPA use of extra risk models and extra
risk models are recommended by various Agency guidances
(e.g-BMDS Technical Guidance).
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be constant. The SACC recommends that EPA
reanalyze the mesothelioma data for NC textile mills
using the expanded Peto model in order to more
accurately account for the variable asbestos exposure
patterns in the NC cohort.
• Recommendation 56: Reanalyze the NC mill data on
mesothelioma using a modified Peto model that
incorporates a non-zero background and accurately
accounts for variable exposures.
PUBLIC COMMENTS:
• EPA should acknowledge the existence of a background
rate for mesothelioma for the development of the IUR
for both lung cancer and mesothelioma.
• Numbers of future mesothelioma cases were projected
through 2055 based on analysis and modeling of SEER
data through 2005 bv Price and Ware (2009) and bv
Moolgavkar et al. (2009). Commenter updated the
analvsis reported in Price and Ware (2009) using SEER
data through 2016. The results in Figure 2 indicate that
by the year 2040 virtually all mesotheliomas in the US
will be background cases. Therefore, there is little, if
any, justification for conducting additional research,
interventions, or regulations to further limit exposure to
asbestos for controlling the occurrence of new
mesotheliomas.
• Incidence curves of non-asbestos related mesotheliomas
in Moolgavkar et al. (2009) could be a starting ooint for
an analysis that recognizes that mesothelioma occurs
without asbestos exposure. In the United Kingdom, the
Tan and Warren (2011) has developed models, one
Durelv statistical Tan and Warren (2009) and the other
based on the two-stage clonal expansion (TSCE) model,
for mesothelioma rates in the population that allow for a
background rate. Similarly, Banaei et al. (2000)
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proposed a method based on the Armitage-Doll
multistage model for analyses of mesothelioma
mortality in France. Another option is to extend the
Peto-Nicholson model, as described in Berman and
CrumD (2008a, 2008b), to include a term for non-
asbestos-related mesothelioma.
• EPA assumed the background risk of malignant
mesothelioma is zero. Numerous studies have estimated
the background risk of mesothelioma to be nonzero and
risk assessments must acknowledge this evidence
(Moolsavkar et al. (2009; Price and Ware (2009; Teta et
al. (2008; Rossli (2007; Price and Ware (2004;
McDonald and McDonald (1994; Ilsren and Browne
(1991; Mcdonald (1985; Walker et al. (1983; Mcdonald
and Mcdonald (1980). Various epidemiolosv-tvpe
studies report fractions of mesothelioma cases without
having been exposed to asbestos or having experienced
onlv low-level exposure (Glvnn et al. (2018; Soirtas et
al. (1994; Peterson et al. (1984; Peto et al. (1981;
Vianna and Polan (1978)
• Tomasetti et al. (2017); Tomasetti and Voselstein
(2015) estimated that the maioritv of all cancer risk,
about 67%, is due to biological processes with outcomes
of background cases. In Tomasetti and Voselstein
(2015), Wu et al. (2016), and Tomasetti et al. (2017),
there is reliable evidence that there are other causes of
malignant mesothelioma besides asbestos, and that
malignant mesothelioma occurs in the absence known
causes (i.e., there is a non-zero background rate). Other
known causes of mesothelioma besides asbestos include
ionizing radiation, erionite, fluoroedenite, and age.
Recent literature suggests that inherited/germline BRCA
associated protein 1 (BAP1) mutations are associated
with very high risk of mesothelioma, as well as Carbone
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et al. (2019; Carbone et al. (2016; Cheuns et al. (2013).
Also in the literature are various articles addressing the
involvement of hereditary cancer syndromes in the
development of mesothelioma (Shih and Kradin (2019).
EPA's calculations must be revised to include estimates
of the background mesothelioma rates in different age
and sex categories that are supported by scientific
literature.
• The data in Figure 1 [Consumption of asbestos in the
US obtained from the United States Geological Service;
male age-adjusted incidence of mesothelioma from the
SEER database; and female age-adjusted incidence of
mesothelioma from the SEER database] support the
existence of background mesotheliomas. Male workers
historically experienced increasing and high-level
occupational exposures to asbestos starting in the 1930s
and relatively high rates of mesothelioma starting in the
1970s. The trend in mesothelioma incidence among
males continued to increase up to the 1990s. Following
the peak in male mesothelioma in the 1990s, male
incidence began to fall in response to substantially
lower exposure levels in the workplace, which to a great
extent were due to OSHA limits imposed on
occupational exposure (37FR 11318; 51 FR22612; 59
FR 40964). The historical trend in mesothelioma
incidence for males associated with high workplace
exposures to asbestos conceals the existence of any
trend for background mesotheliomas among males.
However, during the same time-period, the female
mesothelioma rate remained relatively constant despite
the increase in domestic, product use, and
environmental exposures. Female environmental
exposures to asbestos released from mining,
manufacturing, and product use (e.g, construction
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materials found in the home and other asbestos-
containing products possibly including cosmetic talc)
also would have increased during the 1930-1970 period
and beyond for as long as the asbestos-containing
products were in use. Notwithstanding the increases in
exposure, the mesothelioma rate for women in the U.S.
did not increase. The mesothelioma rate for women in
the US is a reasonable approximation of the background
rate for the disease (Moolsavkar et al. (2009; Price and
Ware (2009. 2004; Weill et al. (2004; Ileren and
Wasner (1991; Gibbs (1990; Mcdonald (1985).
• The pleural mesothelioma rate is higher in those who
have had chest radiation treatments for cancer at mid-
life during the 1950-1970/1980s (and who were never
exposed to asbestos). Additionally, peritoneal
mesothelioma often occurs in persons in their 30s to 50s
when their exposure history indicates that they were
always office workers (not to mention that the latency
would not be consistent with the disease if it was solely
due to asbestos exposure). Mesothelioma clearly occurs
without exposure to asbestos in probably 20-25% of
cases, if not more. As the typical American enjoys
greater longevity, there is increased incidence of
mesothelioma that is independent of asbestos exposure.
• There is a background rate of mutation and hence of
cancer development. Exposure to environmental agents
simply accelerates this background process. In the
original 1986 document (U.S. EPA (1986), the IUR is
based on the concept of excess risk. The current DRE
should do the same in their estimate of KL.
• By basing risk assessments for both lung cancer and
mesothelioma on excess risk and on models that
explicitly consider both 1) concentration of asbestos and
2) temporal factors such as duration of exposure, EPA
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would take a unified and scientifically rigorous
approach to the risk assessments. All the elements
required for such a unified approach are already
available.
• Base IUR for both lung cancer and mesothelioma on
excess risk model, not extra risk model.
4.32 Risks are underestimated due to lack of an unexposed group for internal analyses
63, 92
PUBLIC COMMENTS:
• Internal exposure-response analyses within the cohorts,
reduces bias and confounding. However, none of the
included studies had an unexposed internal reference
group. While analyses by cumulative exposure allowed
meaningful exposure-response determinations, risks are
likely underestimated due to this lack of an unexposed
group for internal analyses. For example, the SC study
(Hem et al. (20071 Table 3) shows an excess risk of
lung cancer (SMR=1.54, 95% CI 1.07-2.15) among
workers in the lowest category of cumulative exposure
(<1.5 f/cc-year) when compared to the US population.
Hein et al. (2007) Table 1 shows that the range of cumulative
exposure in this cohort was 0.1 - 699.8 f/cc-years and the
analyses of this cohort that EPA considered did not rely on
categorical exposure analyses, rather the exposure was
modeled as a continuous variable across the whole range of
cumulative exposure values. Therefore, EPA does not
believe that the cancer potency values derived from this
cohort underestimate risks in the manner the commenter
suggests.
4.33 Use a more appropriate "midpoint" for the highest exposed category
SACC
SACC COMMENTS:
• High exposures may have an undue influence on the
overall model fit.
• Recommendation 51: In the fit of the linear model to
grouped data, set the "midpoint" for the highest exposed
category to be the median or average exposure for
individuals belonging to the group. The IURs estimated
from the linear model were generally higher and thus
using them would be more health protective.
Furthermore, if EPA is going to continue to report the
grouped linear model results, the analysis should be
redone to use a more appropriate "midpoint" for the
highest exposed category that better reflects the typical
Following this and other SACC recommendation, EPA
changed (where it was able to obtain data) the midpoint of
the exposure groups to the mean. EPA also notes that
Dublished simulation results (Richardson and Loomis (2004)
show that midpoint and mean are, in general, both
reasonable. EPA also provided more details of modeling in
Appendix I.
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exposure for individuals belonging to that group. The
median of exposures in the category, rather than the
midpoint of the range, is a more appropriate estimate.
The write-up of this analysis in Appendix J also needs
to be better documented.
4.34 Method for correcting for underascertainment of mesothelioma
SACC,
34, 39,
40, 65,
90, 92
SACC COMMENTS:
• The DRE acknowledges the challenge of under-
ascertainment of mesothelioma and EPA's approach to
adjust the mesothelioma unit risk by 1.39 (0.80-2.17).
This adjustment for mesothelioma ascertainment is
likely too low. The sensitivity of death certificates for
identification of malignant mesothelioma is
approximately 40-50% for deaths prior to ICD-10 and
80% in the initial years that followed the advent of ICD-
10 in 1999. Importantly, most of the deaths in both
textile cohorts occurred before the application of ICD-
10, so that the earlier time period under-ascertainment
estimates would apply to most of the mortality
experience of the cohorts. Hence, the adjustment for
mesothelioma under-ascertainment should be closer to
2.0 for the time periods covered by the relevant
mortality studies.
PUBLIC COMMENTS:
• EPA's correction for under-ascertainment of
mesothelioma was inappropriate and would be obviated
if EPA had used a relative risk model for mesothelioma.
If EPA's concern is correct, it provides a compelling
argument against using its absolute risk model for
mesothelioma and justifies using a relative risk model
for mesothelioma. (34-29)
• The method for deriving the correction factor of 1.39
was highly dependent on assumptions about the number
According to other SACC recommendations, EPA changed
its approach to use North Carolina data in chrysotile IUR
calculations and used post-1999 data in the analysis. For
reasons articulated by this SACC recommendation, mean
under-ascertainment factor (1.39) is more appropriate for this
situation, and EPA continued to use this factor.
As to suggestion by a public commenter of a relative risk
model, EPA have used absolute risk model for mesothelioma
since 1986, and SACC found this model appropriate to use
(see comment 4.31).
EPA clarifies that the perception of lack of significance is a
misunderstanding that this is an adjustment factor and testing
of a statistical hypothesis is thus, not appropriate.
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of missed mesothelioma cases, particularly peritoneal
mesotheliomas. Insofar as peritoneal mesotheliomas are
rarely, if ever, seen among chrysotile-exposed cohorts,
this correction factor is inappropriate for use in
chrysotile asbestos risk assessment. EPA provided no
justification for using it in the DRE. Kopylev and
colleagues provided another, smaller correction factor
based solely on underestimation of mesothelioma cases
on death certificates, and not on the number of missed
peritoneal mesothelioma cases. EPA chose not to use
that smaller correction factor, even though, according to
its own reliance materials (Kopylev et al. (2011). it
would have been more appropriate.
• Kopylev et al. cautioned "The mean ratio of 1.39
implies that the estimated risk of exposure to the Libby
amphibole asbestos would be approximately 1.4 times
larger if all decedents for whom medical information
and pathology samples would have supported a
diagnosis of mesothelioma had been identified."
(Kopylev et al. (2011). EPA erroneously invoked an
implausible correction factor to deal with possible
mesothelioma under-ascertainment in the North
Carolina and South Carolina textile cohorts, while it
ignored the studies of the Quebec chrysotile asbestos
miners (Liddell et al. (1997) and Balangero chrysotile
asbestos miners (Ferrante et al. (2020; Pira et al. (2017)
in which all decedents for whom medical information
and pathology samples supported a diagnosis of
mesothelioma were identified, and in which under-
ascertainment of mesothelioma cases was not an issue.
• EPA should provide an appropriate justification for the
need for an artificial inflation factor to compensate for
under-ascertainment of mesothelioma incidence. In the
analyses, all mesothelioma risk is assigned to exposure
from the studied workplace regardless of time spent at
that workplace, thereby inflating the risk associated
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with site-specific exposure. There is no way to adjust
for this over-estimation of risk, but EPA should not
compound the problem by artificially inflating
mesothelioma incidence.
• It is unclear why EPA includes a risk multiplier derived
from historical datasets to account for potential
undercounting of mesothelioma cases in the current risk
assessment, given that only the 4 mesothelioma deaths
from the NC cohort that were coded according to the
ICD-10 were used to derive the chrysotile asbestos IUR
value (p. 144). The Draft RE for Asbestos states: "EPA
modeled the exposure-response for mesothelioma using
data from 1999 onward when ICD- 10 was in use" (p.
144). Exposure-response data prior to 1999 (which
includes the 4 pleural cancers observed in this cohort)
were excluded from EPA's analysis.
• The risk multiplier value of 1.39 does not appear to be
statistically significant (CI: 0.8-2.17). Further review
and discussion of this issue is warranted.
• While the mean ratio of the posterior distribution is
1.39, it was not statistically significantly different than
1. In fact, it was estimated with 90% probability that the
true ratio is between 0.80 and 2.17. Thus, the possibility
of over-counting mesothelioma cases also exists.
Furthermore, Loomis et al. (2019) attempted to reduce
undercounting of mesothelioma by examining death
certificate data for any mention of mesothelioma and for
codes often used before there was a specific ICD code
for mesothelioma. Therefore, without specific evidence
of undercounting of mesothelioma among the textile's
studies, EPA has no basis to assume this occurred.
• It would be beneficial to further understand the specifics
behind EPA's multiplier of risk for mesothelioma
deaths before and after the introduction of ICD-10. This
multiplier is based on the Libby Worker cohort and is
said to be agnostic to fiber type, but this should be
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confirmed given the potential implications of EPA's
multiplier of risk of 1.39 (CI = 0.8-2.17). Interestingly,
if the confidence limit (precision of which is not
specified) has a lower limit of 0.8, does that mean EPA
would 'remove' cases as a false positive if the lower
bound were used? (p. 151, lines 5587-5592).
• EPA's risk evaluation likely underestimates
mesothelioma mortality, even with the current
adjustment in the model. The 1.39 multiplier appears
more appropriate for studies using death certificates
coded using ICD-10 codes but seems too low for studies
prior to ICD-10.
4.35 Male and female lifetables are different
39
PUBLIC COMMENTS:
• The original IUR developed in 1986 was based on
separate lifetable analyses in males and females, as
shown in Table 1 in comment letter #39. Since male and
female lifetables are distinctly different, this approach is
reasonable, but does not appear to have been adopted in
the current Draft RE for Asbestos. If not, why not?
Since 1986, the EPA has changed its approach and lifetable
analysis for combined males and females is routinely used,
so EPA followed recent EPA precedent. Also, the difference
between male and female lung cancer rates in recent
lifetables is less pronounced than in 1986.
4.36 Consider effect modification by age
39, 42
PUBLIC COMMENTS:
• Effect modification by age refers to the phenomenon
that the RR of exposure often depends upon age. For
many exposures, RR at older ages is significantly lower
than RR at younger ages. This phenomenon occurs, not
because the absolute risk associated with an exposure
decreases, but because the background risk increases
rapidly. Analyses of the same data used by EPA in the
current Draft RE for Asbestos shows that the RR
associated with a given cumulative exposure to asbestos
is highly dependent on age. This dependence of RR on
age has a huge impact on the estimation of IUR based
EPA has identified the best available data to describe the
cancer potency factors for lung cancer and mesothelioma and
applied those potency factors in the lifetable analyses across
all age groups after accounting for a 10-year lag in exposure
for lung cancer. EPA did not have reasonably available data
on age-specific cancer potency factors, but EPA did use the
best available data on age-specific cancer incidence rates and
age-specific mortality data to derive the IUR.
The IUR, and the partial lifetime estimates of the IUR,
reflect the combination of the relative risk of lung cancer and
the absolute risk of mesothelioma. As the risk function for
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on life-table analyses. Thus, even if the SC textile
workers' cohort is considered to be appropriate (which
it is not) for the lung cancer IUR, the analysis used by
EPA in the Draft RE for Asbestos leads to unreliable
results and to a large over-estimation of the true IUR
developed with proper adjustment of effect modification
by age.
• The incidence of pleural mesothelioma increases with
age (even in unexposed cohorts), just like every other
cancer.
mesothelioma directly depends on age at first exposure, the
partial lifetime IUR decreases with increasing age at first
exposure as would be expected since the fibers have less
time to initiate and promote cancers.
4.37 Considering detailed temporal aspects of exposure for lung cancer exposure-response model
39
PUBLIC COMMENTS:
• EPA's lung cancer risk analyses are based on an
exposure-response model in which exposure is
measured as cumulative exposure in f/ml-yr. It is now
generally recognized that cumulative exposure, which is
a product of intensity and duration of exposure, is a
poor measure for the understanding of exposure-
response relationships and that, whenever possible,
intensity of exposure should be considered separately
from time-related factors in exposure, such as duration
of exposure and time since exposure ceased. This is the
approach taken by EPA for the derivation of the IUR for
mesothelioma. When individual-level exposure
estimates are available, such analyses are always
possible, although perhaps more difficult than
traditional analyses using cumulative exposure.
Individual-level exposure estimates are available in
EPA's chosen cohort for lung cancer, the South
Carolina cohort. Following Richardson (2009), whv
does EPA not consider detailed temporal aspects of
EPA did not have access to the temporal or intensity data
necessary for the suggested approach to modeling.
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exposure for lung cancer, as it has done for
mesothelioma in the NC cohort?
• Base both lung cancer and mesothelioma analyses on
detailed exposure histories and on models that explicitly
incorporate both intensity of exposure (concentration)
and temporal factors, such as duration of exposure and
time since exposure ceased. For mesothelioma, EPA
already does this with the Peto-Nicholson model (except
that an extra term will have to be introduced into the
model to incorporate a non-zero background rate). For
luns cancer, Richardson (2009) has already applied this
approach using the two-stage clonal expansion (TSCE)
model to the South Carolina textile workers' cohort, the
very cohort on which the current IUR for lung cancer is
based.
• In parallel with the use of the Peto-Nicholson model for
mesothelioma, use a model for lung cancer that takes
individual-level exposure into account and recognizes
that temporal pattern of exposure is important in
determining risk.
4.38 Clarify how lag period is incorporated
SACC,
65
SACC COMMENTS:
• Recommendation 103: Clarify how the exposure las of
10 years is incorporated into the dose response
modeling and discuss the influence of this assumption
on final estimates.
PUBLIC COMMENTS:
• EPA used a lag in their analysis for lung cancer "to
exclude recent exposures since lung cancer effects
usually take at least 10 years to become apparent" (p.
137, In. 5030-5032). However, it isn't clear that such a
lag was done for mesothelioma, where the latency
period is even longer. There is a factor in the model for
The risk evaluation was updated to clarify that cumulative
exposure lagged by 10 years was used in lung cancer results
reported for all the cohorts (Tables 3-3 to 3-8). For
mesothelioma, the Peto model (Section 3.2.4.4.1) shows that
there is no lag, as there is no cumulative exposure metric to
be lagged.
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time since first exposure (p. 137, In. 5062-5065) but it is
unclear if this is a lag (does not appear to be).
4.39 Latency of mesothelioma
42
PUBLIC COMMENTS:
• Some have postulated that the latency of mesothelioma
maybe 30-35 years or even as high as 45 years. It is
highly unlikely that the latency is longer than 40 years,
except for perhaps radiation, but that has also been
questioned in recent years. Without a lung biopsy,
spontaneous mesotheliomas are indistinguishable from
mesotheliomas due to asbestos exposure. Given the few
workers with appreciable exposure after about 1975—
1980, it is much more likely that any mesotheliomas
after 40 years of the date of last exposure are
spontaneous instead of the suggestion that the latency
continues to get longer than once thought.
EPA agrees that the latency period for mesothelioma may be
very long and notes that the detection of the maximum
latency period necessarily depends upon the length of
follow-up for disease-specific mortality.
4.40 Smoking as a confounding variable
SACC,
39, 42,
65,71,
76, 82
SACC COMMENTS:
• While the text states that smoking is not an important
confounder because it is not correlated with exposure, it
would be better to have this statement further supported.
The SACC wondered if there are any data, even on a
sample, that could be used as support for this
assumption. There is literature on the prevalence of
smoking in certain workers, and this should be used at
least as a possible estimate (Olsson et al. (2020).
Similarly, age at which a worker started (and stopped)
smoking may be more relevant for lung cancer than the
age at which that individual started (and ended) working
in an asbestos facility, and this aspect should be at least
discussed (Girardi et al. (2020). Recommendation 69:
Further discuss and justify the assumption that smoking
Regarding the potential for smoking to confound lung cancer
risks in occupational cohorts, EPA acknowledges that
confounding of the asbestos-lung cancer relationship is
certainly a theoretical possibility and such comments are
reasonable. However, decades of occupational epidemiology
studies have shown few examples of any meaningful
confounding of occupational exposures by smoking. The
folio winy lone citation from Blair et al. Blair et al. (2007)
summarizes a lesson in understanding potential confounding:
"Confounding occurs when a factor is associated with the
outcome in the absence of the exposure of interest and also
with the exposure of interest. For confounding to occur, the
factor must be a risk factor for the outcome and also
correlated with the exposure of interest (Checkowav et al.
(2004). What mav not be as well appreciated is that for
confounders to have much of an impact, both associations
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is not correlated with occupational exposures to
chrysotile asbestos.
PUBLIC COMMENTS:
• In studies of lung cancer in which smoking was
considered and controlled for among these workers, 12
case-control studies (Corbin et al. (2011; Guida et al.
(2011; Consonni et al. (2010; Macarthur et al. (2009;
Richiardi et al. (2004; Matos et al. (2000; Swanson et al.
(1993; Morabia et al. (1992; Benhamou et al. (1988;
Vineis et al. (1988; Lerchen et al. (1987; Williams et al.
(1977) and two cohort studies (Veglia et al. (2007;
Hrubec et al. (1995; Hrubec et al. (1992) reported no
increased risk for lung cancer when compared with the
general population.
• During the lung cancer epidemiology for the era in
question (the 1940s to 2000s), a substantial portion of
the male worker population smoked. Without a
comprehensive smoking history for each person or a
comprehensive knowledge of the exposure to various
forms of asbestos (and other airborne carcinogens),
these studies cannot be used to identify a "chrysotile
only" potency factor for lung cancer. As discussed in
Goodman et al. (1999). there can be considerable
heterogeneity in smoking habits between occupational
groups and the controls. Other potential confounders
such as a person's smoking history (pack-years, the age
they started and the age they stopped) should be
considered.
• The confounding role of smoking in lung cancer is
downplayed. This is incorrect when considering both
epidemiological and mechanistic studies which point to
critical roles of cigarette smoke in impairing clearance
of asbestos fibers from the lung and initiation of these
tumors (Mossman and Gee (1989).
• Unlike for mesothelioma, differences in lung cancer
mortality levels are highly sensitive to cigarette
(i.e., risk factor for the disease and correlation with the
exposure of interest) must be strong (Breslow and Day
(1980). If this is not the case, the impact of confounding
cannot be large. Situations fulfilling these requirements are
not common. Despite these rather stringent requirements, we
find that many scientific discussions about potential
confounding seem to assume that it is common, and its
impact is sizable. Typically, the potential for confounding is
hypothesized because some putative risk factor for the
outcome of interest, or because some factor thought to be
correlated with the exposure of interest has not been
addressed in the study design or in the analyses. For
example, in evaluating a study of a specific pesticide and
lung cancer risk, suspected or established lung carcinogens
(with no evidence of a linkage with the pesticide of interest),
or other exposures that may coincide with the pesticide of
interest (with no indication that they cause lung cancer) may
be suggested as possible confounders. In such discussions, it
is unusual for both associations to be considered and even
rarer for the magnitude of these associations to be evaluated
and for supportive data to be provided.
In occupational epidemiology, tobacco or other occupational
exposures are commonly raised as potential confounders,
particularly with retrospective cohort studies, since these
studies often lack information on these factors. However,
even without direct information on their occurrence or
magnitude in the population under study, the possible impact
of such confounding can be estimated.
For example, consider tobacco use as a confounder. Axel son
(1978) made an extremely important contribution to this
issue when he demonstrated that confounding from tobacco
use in occupational studies of lung cancer was unlikely to
entirely explain relative risks greater than 1.6. So, even
without information on tobacco use, the Axelson approach
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smoking rates of cohort members, and this may explain
some of the differences between predicted and apparent
excess numbers of lung cancer rates.
• There is no mention of the multiplicative effect
modification of smoking on risk for mesothelioma and
lung cancer. EPA infers effect modification by smoking
via noting that smokers are a potentially susceptible
population (e.g, p. 23, In. 978-983), but they do not
account for the potential multiplicative effect of
smoking on risk estimates.
• EPA should acknowledge and analyze a relationship
between cigarette smoking and mesothelioma.
Commenter cites detailed analysis by Moolgavkar and
colleagues of the mixed evidence of an association
between smoking and mesothelioma.
Axelson (1978) could be used to set boundaries regarding the
likely impact of smoking confounding. This approach was
further evaluated and extended to additive models by Gail et
al. (1988). Using these approaches, the occurrence and likely
magnitude of confounding by tobacco can be reasonably
estimated because we have a considerable amount of
information on relative risks from tobacco use for many
diseases, as well as information on tobacco use by various
occupations or exposures (Brackbill et al. (1988); Stellman et
al. (1988). With this information, it is relatively easy to
estimate the potential impact of confounding by smoking, as
suggested by Axelson (1978). thus, negating the need for
pure speculation. Kriebel et al. (2004) extended this
technique of indirect adjustment in a quantitative evaluation
of the possible effects of confounding by tobacco and
alcohol use in occupational studies. They concluded that
changes of greater than 20% were unlikely.
The potential for confounding by tobacco can also be
evaluated by assessing the correlation between smoking and
specific occupational exposures. This may not always be
possible because the necessary information is often not
available. However, Siemiatvcki et al. (1988) evaluated the
relationship between level of exposure to 10 common
occupational exposures (sulfur dioxide, welding fumes,
engine emissions, gasoline, lubricating oil, solvents,
paints/varnishes, adhesives, excavation dust, and wood dust)
and tobacco use using data from a case-control study in
Montreal. They found no correlation between occupational
exposure indices for any of these substances and smoking
history. Of course, tobacco use could be associated with
other occupational exposures, but these data suggest that a
strong association between smoking and specific exposures
is unlikely."
EPA notes that in the IRIS Toxicological Review of Libby
Amphibole Asbestos, EPA conducted specific analyses
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designed to detect potential confounding and found no
statistical support for such confounding in another cohort
study of asbestos effects on lung cancer.
The weight of the evidence is that the potential for
meaningful confounding by smoking is small. EPA is
confident that confounding by smoking is not an issue of
concern in the analyses that support the derivation of the
IUR.
Regarding potential confounding of the relationship between
asbestos exposure and mesothelioma, the commenter's
citation of a few selected studies from the 1970's does not
provide evidence of potential confounding. EPA is not
aware of evidence of smoking confounding mesothelioma
effects. EPA notes that IARC Monograph 100C (2012) on
asbestos states "Malignant tumours arising in the pleural or
peritoneal linings (diffuse malignant mesothelioma)
have no association with tobacco smoking" and Cogliano et
al. (2012) do not mention smoking as a risk factor for
mesothelioma (Blair et al. (2007; Siemiatvcki et al. (1988)
4.41 Level of asbestos mortality in population
76, 47,
48,51,
73, 92,
31,58,
99, 86,
97, 57,
104
PUBLIC COMMENTS:
• To evaluate the Draft RE for Asbestos IUR, one
commenter applied it to previously studied cohorts for
which exposure data have been collected and cancer
incidence rates are known. They concluded that it is
necessary to establish an IUR that will correlate better
with known risks and existing epidemiology.
• Based on the "high end" exposure estimates for the NC
cohort, that the IUR predicted levels of excess cancer
approximately 80 times higher than observed for
EPA derived the IUR using multiple Agency guidances as an
upper bound of what happens at lifetime exposure starting
from birth. Because IURs are upper bound estimates of risk,
they are not suited to such post-hoc estimations of case
counts provided by the commenters who appeared to use
them as central estimates of risk. In assessing risks of less-
than-lifetime exposures to chrysotile, such as for miners, the
commenters should use the appropriate partial lifetime IUR
values specific to the exposure scenarios. Applying a
lifetime IUR to populations exposed in adulthood would
likely explain the overestimation of risk observed by one
commenter.
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mesothelioma and 3 times higher than observed for lung
cancer.
For the Quebec miners epidemiological study, the
overestimation of risks using the Draft RE for Asbestos
IUR is considerable. And the Draft RE for Asbestos
IURs predict a ratio between the upper bound
estimations of lung cancer and mesothelioma risk to be
1 to 2.3, while the ratio observed in the epidemiological
data for the cohort was 4.7 to 1, reversing the
proportion.
The Draft RE for Asbestos chrysolite IUR applied to the
new Italian cohort study (Ferrante et al. (2020) for 974
male workers from the Balangero mine resulted in a
large overestimation of mesothelioma and lung cancer
cases compared with those observed for the cohort.
Whereas, the average IUR from the Berman and Crump
(2008a) and Hodgson and Darnton (2000) central
tendency estimate closely agreed with the observed
Balangero cases.
The proposed IURs predict the relationship between
excess mesothelioma and lung cancer cases to be
"reversed" from what was observed for the NC cohort
used to derive the IURs. The ratio between lung cancer
and mesothelioma was observed as 13.2 to 1, while the
proposed IURs (considering the underlying EPA IURs
separately for lung cancer and mesothelioma) would
predict a ratio of 1 to 2.3. The ratio predicted using the
Berman and Crump and Hodgson and Darnton IURs
was 10 to 1, matching the published data with
reasonable accuracy.
Draft RE for Asbestos understates the risk to public
health.
Although EPA has determined that asbestos presents
unreasonable risks under the limited COUs it addresses,
several commenters are concerned that these risks are
greatly understated.
EPA has revised the derivation of the IUR to include the
linear model for lung cancer and has developed adjustment
factors to account for other cancers.
In response to public comments on ratio of lung cancer and
mesothelioma, EPA notes that both in 1988 EPA risk
evaluation for general asbestos (U.S. EPA (1988a). and in
recent IRIS risk assessment of Libby Amphibole asbestos
(U.S. EPA (2014c). lifetime risk of mesothelioma exceeded
lung cancer risk, so this risk evaluation of commercial
chrysotile asbestos is consistent with prior EPA assessments.
EPA prioritized Asbestos as one of the first 10 chemicals to
undergo risk evaluation under TSCA, recognizing the
importance of evaluating risks from asbestos to human
health and the environment from asbestos. EPA considered
all reasonably available information and considered all
public comments and SACC input on the draft risk
evaluation in reaching final conclusions on risk for current
conditions of use of chrysotile asbestos in Part 1 of the risk
evaluation for asbestos. EPA noted uncertainties throughout
and accounted for those uncertainties where possible. EPA
will further consider risks in Part 2 that are related to legacy
uses and associated disposal for all 6 fiber types included in
AHERA II definition.
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• The Draft RE for Asbestos sets aside the linear dose-
response risk model without evidence that the
exponential risk model is better. The Draft RE for
Asbestos also considers a single fiber type among the
six asbestos types in commercial use; two of the four
cancers recognized by IARC as asbestos-related are
ignored; nonmalignant disease is ignored; and legacy
asbestos, a particular risk in public schools, is set aside
for another and uncertain day.
• Some of the outdoor exposure scenarios for consumers
and bystanders might shift from a "no unreasonable"
finding to an "unreasonable" finding if the
recommended modifications to the exposure scenarios
were implemented.
• EPA is obligated to determine if underestimation is the
case and to what degree. The non-cancer toxicity of
chrysotile may be greater than that of Libby amphibole
asbestos, and there is uncertainty that the IUR for
chrysotile asbestos may not fully encompass the health
risks associated with chrysotile exposure.
• The death toll from asbestos exposure in the US remains
alarmingly high. Furuva et al. (2018) reported that
asbestos-related diseases are causing on average 39,275
deaths in the US annually, more than double the
previous estimates of 15,000 per year.
• Asbestos is likely the most hazardous substance in
widespread use since the industrial revolution and is
responsible for millions of deaths worldwide (51-183,
86-2, 97-1). Asbestos has taken the lives of over a
million Americans and continues to kill nearly 40,000
people in the US each year.
• Asbestos use has declined but the Draft RE for Asbestos
indicates that the remaining active uses result in
asbestos exposure by over 1.5 million workers and up to
32 million "do-it-yourself consumers who replace
asbestos brake pads and clutches. This is without
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counting the millions of Americans who are exposed to
legacy asbestos but are outside the scope of the EPA
evaluation.
• From 1991 to 2017, more than one million Americans
died from preventable asbestos-caused diseases (Ghdx
(2017). These deaths are onlv a snapshot in time; the
total number of deaths during the 100+ years of asbestos
use is much larger.
• Despite the elimination of many asbestos products due
to corporate liability, asbestos deaths—calculated to be
nearly 40,000 per year as noted above—remain high,
demonstrating that millions of Americans have been
significantly exposed to asbestos in the past and many
others are exposed now.
• Based on OSHA's risk estimates for worker deaths from
exposure to asbestos in the US, workers will continue to
die at rates higher than 1 in 10,000. There are countless
others not covered by OSHA who work with or use
products containing asbestos. Consider legacy asbestos
found in buildings and products still in use such as lamp
sockets, floor covering, cat box fill, braking mechanism
in washing machines and cars, furnaces, dishwasher,
asbestos cement water pipes, and many, many more
products. Because many of these products have been
brought into the US while others of these products were
manufactured by workers in the US, they are also used,
maintained, and repaired by workers in the US causing
additional exposure from such consumer products
and/or to environmental levels of asbestos which are not
accounted for in the current EPA risk estimates.
4.42 Consider conducting meta-analyses
76
• In its Cancer Risk Guidelines, U.S. EPA (2005)
emphasized the importance of meta-analysis: "This
EPA developed data quality evaluation criteria and selected
studies of best quality for deriving the chrysotile IUR (see
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technique is particularly useful when various studies
yield varying degrees of risk or even conflicting
associations (negative and positive). It is intended to
introduce consistency and comprehensiveness into what
otherwise might be a more subjective review of the
literature." Although EPA has stressed the limitations of
the meta-analysis approach, it has been repeatedly
applied to asbestos epidemiology and risk assessment.
• In particular, Berman and Crump (2008a. 2008b) and
Hodgson and Darnton (2000) performed two of the
most widely cited meta-analyses on asbestos exposure
risk, not only considering duration and age of exposure,
but also including fiber types, and in some cases, fiber
dimensionality.
• The commenter developed an Excel spreadsheet risk
calculator, using the methods of Berman and Crump
(2008b) and Hodgson and Darnton (2000) (linear
approach), which performs specific risk calculations
based on intensity, duration, and age of first exposure.
The calculator was independently validated. The
commenter found good agreement between the IURs
that they calculated using their spreadsheet and
observed cohort data, including the Quebec cohort (see
comment letter for details) (76-16), and the Connecticut
chrysotile asbestos friction products plant.
• The Berman and Crump (2008a) method includes a
maximum likelihood estimation (MLE) approach that
allows consideration of the amphibole asbestos fraction
in various mixed fiber cohorts, significantly expanding
the number of studies for the meta-analysis and
increasing the reliability of the potency estimations. The
Hodgson and Darnton meta-analysis allowed inclusion
of cohorts without individuals' detailed exposure
information, relying on a cumulative exposure metric
for the entire cohort. Both approaches yielded similar
IUR levels (effectively validating both approaches) and
Supplemental Systematic Review File for human health
hazard). SACC approved of this strategy by recommending
use of NC and SC cohorts (see responses to Comments 4.10
and 4.13). EPA does not believe that a meta-analysis using
more studies of lesser quality would yield better results.
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averaging the IURs derived from Berman and Crump
and Hodgson and Darnton would yield the central
tendency estimation of the IUR for chrysotile at the
level of 0.0225, approximately 70 times lower than the
average value for crocidolite asbestos.
• The commenter recommended that meta-analysis be
included in the determination of the IUR for chrysotile
asbestos, with due consideration of the statistical data
quality for each of the included and excluded studies.
4.43 Include confidence statements for IUR values
SACC,
40
SACC COMMENTS:
• As was done for previous TSCA chemicals DREs, EPA
should provide confidence statements (High, Medium,
or Low) for IUR values and risk estimates for each
COU. Recommendation 77: Provide confidence
statements for IUR values and risk estimates for each
COU. The SACC seemed to express low-to-medium
confidence in most hazard conclusions and risk
conclusions for COUs in this DRE. Recommendation
78: Key elements of the conclusions presented in
Section 4.5.2 and 4.5.3 should be included in Section 4
for clarity.
• The SACC identified additional uncertainties and
recommended that all uncertainties be classified with
respect to the direction of bias. The factors likely to
result in downward bias (underestimation) include: (1)
focusing only on mesothelioma and lung cancer and
omitting other cancers; (2) the IUR only characterizes
cancer risk; (3) using mortality instead of incidence; (4)
the form of the risk model (linear vs. exponential); (5)
use of the linear risk model for mesothelioma; (6)
under-ascertainment of mesothelioma; and (7) exposure
measurement error in the cohort studies. The factors that
EPA believes it is important to use a consistent approach for
risk characterization and risk determination. Categorical
descriptors for risk estimates have not been used in risk
evaluations under TSCA, and it would take substantial effort
to develop criteria for categorical descriptors and the benefit
is unclear to EPA. Asbestos particle sizes and analytical
methodology have been described where necessary. Study
quality criteria is described in Supplemental Files for Part 1
of the Risk Evaluation, which also include evaluations for
each of the relevant studies.
Regarding the Uncertainties enumerated by SACC:
1) EPA developed an adjustment factor to address other
cancers (more details in Section 4.1 above)
2) The IUR only address cancer risk - by definition.
Non-cancer hazards are now recognized in the
document (more details in Section 4.1 above)
3) The IUR was revised and now addresses cancer
incidence (more details in Comment 4.4. and EPA
response above)
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may result in upward bias (overestimation) include (8)
fiber potency as a function of length and width, and (9)
fiber lengths in current COU exposures being
potentially shorter than fiber lengths from exposures in
the textile mills. Uncertainties where the direction of
bias have not been classified include: (10) exposure
measurement; (11) amphibole and non-amphibole
asbestos contamination (or using chrysotile to represent
all types of asbestos); (12) not considering dermal
exposures; (13) mesothelioma potency adjustment; and
(14) the assumption of no mesothelioma background.
More explicit consideration and presentation of sources
of bias and uncertainty is needed, including estimating
the magnitudes of the two sources of bias identified and
discussed in the DRE, and then using this information to
adjust the IUR.
PUBLIC COMMENTS:
• Additional variables that impact the magnitude of the
IUR were not well described (e.g multiplicative effect
modification of smoking, absolute/relative risk, lag
period, statistical analysis, and the magnitude of the risk
multiplier pre-/post-ICD 10).
• It is not obvious whether or to what extent the estimated
IUR value for chrysotile, which is based solely on
asbestos textile manufacturing settings, is applicable to
imported chrysotile-containing brake repair and
replacement scenarios. This is a major source of
uncertainty in EPA's risk evaluation that should be
acknowledged and discussed in more detail with respect
to these COUs.
• The possibility that the North and South Carolina
cohorts may also have been exposed to amphibole
asbestos represents a major source of uncertainty that
should be acknowledged and transparently described.
The cumulative exposure of the four mesothelioma
Page 202 of 284
4) The IUR is now based on the linear model for lung
cancer (more details in Comment 4.29 and EPA
response above)
5) The IUR uses the Peto model for mesothelioma
(more details in Comment 4.24 and EPA response
above)
6) Underestimation of mesothelioma ascertainment is
addressed using the adjustment factor in Kopylev et
al. (2011) (see more details in Comment 4.34 and
EPA response above)
7) Exposure measurement error and the potential for
bias towards the null is acknowledged in the
uncertainties section (see more details in 4.3.6 of the
risk evaluation)
8) Fiber length issues related to toxicity are addressed
by comparing the cancer potency values across
industries (see more details in Comment 4.26 and
EPA response above)
9) Fiber length issues related to COUs remain an
uncertainty as the fiber concentration data on COU
exposures are limited to PCM measurements which
do not provided fiber length data (see more details in
Comment 4.26 and response above)
10) See #7 above
11) The chrysotile IUR addresses chrysotile exposures.
Comments suggesting amphibole contamination were
considered, but not found to be credible (see more
details in Comment 4.10 and EPA response above)
12) Dermal exposures were considered, but inhalation
exposures were the focus of this evaluation (see more
details in Comment 1.19 and EPA response above)
13) see #6 above
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cases should also be reported for sake of fully
transparency.
14) The assumption of no mesothelioma background rate
is implicit in the Peto model that EPA has relied on
since the 1986/88 IRIS assessment of general
asbestos. Note that comments submitted regarding
people who had never been exposed having asbestos
fibers in their lungs strongly suggest that recollection
of no asbestos exposure is not reliable and
undermines the contention that there might be a
background rate of mesothelioma. (See more details
in Comment 4.31 and EPA response above).
4.44 Adjust IUR based on potential bias for each individual uncertainty
SACC
SACC COMMENTS:
• Recommendation 53: Avoid usins one bias term to
compensate for others. Recommendation 54: Include the
additional sources of bias identified by the SACC in the
discussion of uncertainties and discuss how these biases
will change the direction and magnitude of estimated
IURs. Data should be used to inform the amount and
direction of potential bias for each individual
uncertainty, and then the IUR estimate adjusted based
on this more detailed assessment. There should be a
section explaining how this "compensation of bias" was
statistically performed and where the suggestion came
from (Draft RE for Asbestos p. 196). There is no direct
relationship between the two sources of bias and the
largest IUR. Data related specifically to the magnitudes
of the two sources of bias addressed in the risk
evaluation should be used to adjust for them. Data on
the time between when lung cancer was identified and
subsequent death from lung cancer could be used to
adjust the risk estimates based on mortality data to
pertain to incidence. Data from studies of human
populations on cancers other than lung and
Following this and other SACC recommendations, EPA
avoided using one bias term to compensate for other terms
and developed separate approaches for different biases (see
response to SACC recommendations in comment 4.1)
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mesothelioma possibly caused by asbestos could be
used to adjust risk estimates to account for these
cancers.
4.45 Other suggested changes to content
42,
71, 82,
103
PUBLIC COMMENTS:
• EPA should apply genomic risk analysis tools for all
asbestos-associated cancers. Mesothelioma is often the
focus of asbestos-related risk assessment. However,
other asbestos-associated cancers exist. All should be
part of risk assessment. Comments below should be
read in that context. EPA's risk assessment analyses
also should include recent work by Kenneth T. Bogen,
Dr. P.H., regarding the role of genomic regulatory
mechanisms (i.e. epigenetics) in the development of
cancers. As explained in his work, and the work of
others, expression of genes and transcription can be
amplified or silenced by regulatory genomic
mechanisms that do not directly mutate DNA.
• On p. 133 (In. 4923-4924), the statement "making the
observance of mesothelioma in a population a very
specific indicator for asbestos exposure (Tossavainen
CI997)" is included. Likewise, on p. 134 On. 4940-
4941), it is incorrectly stated that radiotherapy is "the
only other known risk factor for mesothelioma, and this
rare exposure there are unlikely to be a confounder"
(note grammatical errors). These statements/paragraph
should be modified to include more recent observations
showing the importance of other environmental
minerals such as erionite and fluoroedenite, spontaneous
mutations, and germline mutations in causation of
mesotheliomas (Carbone et al. (2019; Mossman et al.
(2013). Peritoneal mesothelioma is less frequently
EPA stated in the Problem Formulation document that
genomic data was out of scope and the chrysotile evaluation
would rely on epidemiologic data. SACC agreed with this
approach.
EPA has corrected the grammatical error.
EPA has edited the text on other causes of mesothelioma to
acknowledge that erionite and fluoroedenite are also causes
of mesothelioma.
EPA considers health effects of asbestos, such as cancer, as
severe and irreversible. This is not in conflict with peer-
reviewed literature.
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associated with asbestos exposure (Garbone et al.
(2019).
• On p. 156 (In. 5729-5730) EPA stated "There is some
evidence of a predisposition for mesothelioma related to
having a sermline mutation in BAP1 (Testa et al.
(2011)." This sentence should be expanded to include
additional germline mutations in genes regulating DNA
repair such as MLH1, MLH3, TP53 and BRCA2, that
have been discovered in the last decade (Carbone et al.
(2019; Mossman et al. (2013).
• The Draft RE for Asbestos contains several statements
inconsistent with the peer-reviewed scientific literature.
"The Agency also considered that the health effects
associated with asbestos inhalation exposures are severe
and irreversible" (Draft RE for Asbestos In. 731-733)
conflicts with the effect of dose-response observations
in human cohorts and animal inhalation experiments
(Bernstein et al. (2020a, b; Mossman et al. (2013).
These studies indicate thresholds for exposure to
asbestos at low concentrations.
• Gradient of association with asbestos by anatomic site
of mesothelioma: The fraction of mesothelioma cases
attributable to asbestos exposure differs by time period
and geographic area due to differences in the prevalence
of asbestos exposure(s) and the magnitude of detected
association(s)
- Pleura - Strongest association with asbestos
exposure (-80% among men and 20% among
women in the U.S. attributable to asbestos
exposure)
- Peritoneum - Weaker association with asbestos
exposure (<10% among men and <1% among
women in the US attributable to asbestos exposure).
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4.46 IUR - general comments
SACC,
42
PUBLIC COMMENTS:
• "[T]his document is among the most thoroughly
transparent analyses that I have read in my 40-year
career as a risk assessor...."
• "It is refreshing to see the Agency be thorough
concerning wanting to make the uncertainties in the
assessment of the IUR transparent. For the topics
discussed, in my view, the agency has done a reasonable
job of identifying many of them."
EPA thanks the commenter for these acknowledgements.
4.47 Clearer documentation of IUR is needed
SACC,
65, 82
SACC COMMENTS:
• Add a graph and discussion of the potency factors,
exposure concentrations (ECs), and lifetime unit risks
across the five cohorts because it is challenging to
digest these differences as currently presented. Finally,
reporting the estimates relative to the target level would
make it easier to digest the reported results.
• Recommendation 92: Present the findings of Table 3-8
in a graph, reporting risk estimates relative to the target
level.
• Recommendation 93: Provide clearer documentation for
IUR calculations, such as those presented in Appendix
I.
PUBLIC COMMENTS:
• Table 3-13 (p. 155) shows the lifetime IUR for
chrysotile asbestos. There is no discussion of how this
IUR relates to other environmental or societal risks.
This is necessary for interpretation of data.
Following SACC suggestions, EPA changed Table 3-8 to
present lung cancer and mesothelioma potency factors from
5 considered cohorts instead of cancer risks. Because goal of
Table 3-8 is to present comparisons between textile and
mining industries, the potency factors are sufficient for the
goal.
EPA also updated Appendix I providing more details on the
modeling.
EPA provided missing details on lag and clarified
presentations throughout modeling sections.
The IUR is a statistic that reflects risk of mesothelioma, lung
cancer, and other cancers relative to exposure to chrysotile
asbestos. It is not clear how environmental or societal risks
could be accounted for in the IUR and no specific
recommendation was made in the public comment.
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5.
Human Health Risk Characterization
Charge Question 5:
5.1 Please comment on whether the analysis presented supports the conclusions outlined in the draft risk characterization section
concerning asbestos. If not, please explain the limitations of these conclusions, and whether there are alternative approaches or
information that could be used to further develop the risk estimates within the context of the requirements stated in EPA's Final Rule,
Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act (82 FR 33726) (Section 4).
5.2 EPA presented overall human health risk conclusions (Section 4.6.2) based on risk estimates for cancer. Please comment on EPA's
approach including any alternative considerations for determining and presenting risk conclusions including the risk summary tables
(Table 4-57 and 4-58).
5.3 Please comment on the clarity and validity of specific confidence summaries presented in Section 4.3.
5.4. Throughout this charge we have asked reviewers to comment on the uncertainties and data limitations associated with the
methodologies used to assess the environmental and human health risks. Please comment on whether that information has been carried
forward to the characterization of the risk evaluation such that the strength of the brake conclusions is characterized in a clear and
transparent manner (Section 4.3).
5.5 Please comment on any other aspect of the environmental or human health risk characterization that has not been mentioned above
(Section 4).
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5.1 Provide more information on assumptions
SACC
SACC COMMENTS:
• The health risk estimates calculated were only for
chrysotile asbestos and did not include the likelihood of
exposure to amphibole asbestos and exposures to mixed
fibers from other uses (industrial talc, drinking water
pipes, etc.). Specifically, SACC members recommended
that more information should be provided on the
assumptions embedded in the health risk derivations.
Recommendation 59: Provide more information on the
assumptions embedded in the health risk derivations.
• The assumptions on PPE use have a large effect on the
risk determinations. Table 4-38 clearly shows the effect
of assuming PPE use on risk determination.
Recommendation 87: Include a more detailed
For evaluation of the COUs included in Part 1 of the Risk
Evaluation for Asbestos (focused on chrysotile asbestos),
EPA applied an IUR specific to chrysotile asbestos. EPA
believes Part 1 of the Risk Evaluation has been revised
throughout to make the focus on chrysotile asbestos more
explicit.
As a result of the court decision in Safer Chemicals Healthy
Families v. EPA, 943 F.3d 397 (9th Cir. 2019), the Agency
will evaluate legacy asbestos uses and associated disposals
of those uses in Part 2 of the Risk Evaluation for Asbestos.
As a part of that effort, EPA will apply an IUR that addresses
asbestos fibers that continue to be present in legacy COUs.
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examination of the actual levels of protection provided
by respirators and take actual levels into account to the
extent possible in calculating risks to workers wearing
respirators.
• The SACC considered the assumptions underlying PPE
use scenarios to be unrealistic, therefore associated risk
estimates should not be considered in the risk
characterization. More realistic and likely scenarios
should be included for evaluation of consumer and by-
stander use of asbestos-containing brakes and gaskets.
While EPA has evaluated worker risk with and without PPE,
as a matter of policy, EPA does not believe it should assume
that workers are unprotected by PPE where such PPE might
be necessary to meet federal regulations, unless it has
evidence that workers are unprotected. For the purposes of
determining whether or not a COU presents unreasonable
risks, EPA incorporates assumptions regarding PPE use
based on information and judgement underlying the exposure
scenarios. These assumptions are described in the
unreasonable risk determination for each COU, in Section
5.2. Additionally, in consideration of the uncertainties and
variabilities in PPE usage, including the duration of PPE
usage, EPA uses the high-end exposure value when making
its unreasonable risk determination in order to address those
uncertainties. EPA has also outlined its PPE assumptions in
Section 5.1.
5.2 Analysis supports conclusions
51,73,
92, 101
PUBLIC COMMENTS:
• Commenters applauded EPA's finding that for almost
every COU evaluated, asbestos has been deemed to
present an "unreasonable risk."
• Decades of unbiased scientific research from around the
world has repeatedly demonstrated that all asbestos
exposure poses unreasonable risks (92-1). Industrial
producers and users of chrysotile have tried to argue
that the serpentine fibers are harmless and that only
amphibole fibers pose cancer risks; EPA's analysis
rejects that conclusion.
• Commenters agreed with the Draft RE for Asbestos
finding that nearly all ongoing commercial and
consumer uses of asbestos reviewed by EPA present an
unreasonable risk of mesothelioma and lung cancer,
EPA appreciates the comment.
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particularly under the occupational COUs evaluated in
the Draft RE for Asbestos and also for consumers.
5.3 Draft RE for Asbestos overestimates cancer risk
42, 60,
65, 68,
72, 95,
144
PUBLIC COMMENTS:
• The chlor-alkali industry has a proven record of the
safe use of asbestos within the chlorine production
process. With the effective engineering and
administrative controls currently in place, including
respiratory protection, a scientifically-based risk
assessment of the chlor-alkali industry's use of asbestos
in chlorine production will demonstrate that this use
does not pose an unreasonable health risk to workers.
• One commenter does not believe that hundreds of
thousands of persons each year in the future may be
exposed to dangerous levels of asbestos. EPA discarded
the OSHA PEL, generated inaccurate exposure
scenarios, and derived a "new" cancer potency factor
for chrysotile alone to conclude that occupational
conditions for the six categories of workers evaluated
by EPA (see Draft RE for Asbestos p. 26) are at "an
unreasonable risk to health."
• Even considering the short-term personal breathing
zone (PBZ) exposures for chlor-alkali industry, the
commenter considered the data to present "an
incredibly narrow range of sample results for short-
term, allegedly high exposure, sampling," well below
the OSHA PEL of 0.1 fibers/cc. That means
statistically, a high level of certainty for the results.
Thus, the commenter did not find that the data
supported a finding of "unreasonable risk."
• EPA found an unreasonable risk to workers in several
COUs (Table 4-54). However, the workers in these
facilities are nearly all exposed to TWA concentrations
well below the current OSHA PEL. As shown in Table
EPA based the risk calculations and the risk determinations
made in Part 1 of the Risk Evaluation for Asbestos based on
reasonably availably information including information
provided by industry. As such, the Agency stands by its risk
determination conclusions. EPA has also adjusted its
estimates of exposed individuals in Part 1 of the Risk
Evaluation for Asbestos based on public comment and
reasonably available information.
EPA derived the IUR using multiple Agency guidances as an
upper bound of what happens at lifetime exposure starting
from birth. Appendix K presents IURs for partial lifetime
exposures starting at various ages.
In regard to the OSHA PEL for asbestos, TSCA compels
EPA to evaluate chemicals without consideration of non-risk
factors (such as feasibility of meeting a standard) to
determine whether they present unreasonable risk under the
COUs. EPA's "no unreasonable risk" standard has not
necessarily been met at the OSHA PEL.
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2-5, there were 650 PBZ samples collected between
1996 and 2017, for which the 50th percentile
concentration was 0.006 fibers/cc, and the upper 95th
percentile concentration was 0.05 fibers/cc (8-hour
TWA full-shift samples). Therefore, those data do not
support a finding of "unreasonable risk" considering
the OSHA PEL (42-144). Exposure data presented by
EPA does not identify any cohorts routinely exposed
above about 1/10 to 1/2 the current OSHA PEL for
asbestos (and the number of plausible workers is very
low).
• Draft RE for Asbestos Table 4-11 presents the ELCRs
for workers stamping gaskets from sheets, using
exposure data from two sampling durations (8-hour full
shift; 30-minute short-term). This scenario is not
important given the low airborne concentrations, the
low potency of short, encapsulated chrysotile fibers,
and the exposures of only one or two employees for a
handful of hours per year. It genuinely should not be of
interest to EPA.
• Table 4-56 provides a summary of risk estimates for
consumers and bystanders. Cancer risks were exceeded
for all consumer and bystander UTV gasket
replacement exposure scenarios (Draft RE for Asbestos
p. 7437-7442). If the person conducting the work is not
at risk, it is implausible that there would be bystanders
at risk. Also, the number of bystanders multiplied by
the risk estimate should equal at least one person
getting cancer for a national regulation.
• API "provided petroleum industry specific information
which indicates that EPA has over-estimated risk both
to workers and ONUs."
• There are so many flaws in the derivation of IURs for
chrysotile (presented in this document) that it is not
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appropriate for anyone to categorize any of these
exposures as "presenting an unreasonable injury to
health." (42-141) In the Draft RE for Asbestos, the
exposure estimates and new IUR for chrysolite asbestos
overestimate risk to occupational workers and ONUs in
general. EPA concluded that exposure to brakes and
gaskets poses a "significant health hazard to workers,"
but the epidemiology and toxicology for that COU
information do not support that claim.
• The lifetime doses for any exposed persons will almost
certainly be 1,000 to 10,000-fold less than those that
might cause an asbestos-related disease.
• One commenter noted that it is clear from the data in
the EPA's document, that few, if any, persons in the
US should ever again be exposed to chrysotile above
trivial concentrations. Lifetime doses will almost
certainly be 100 to 1,000-fold less than those that
should cause an asbestos-related disease. Fewer than
100 persons in the US annually could have measurable
exposure to asbestos today from brakes, gaskets, and
packing (for various reasons). EPA found that the
present an unreasonable risk to workers in several
COUs in Table 4-54. However, the commenter
concluded that the workers in these facilities are nearly
all exposed to TWA concentrations that are well below
the current OSHA PEL of 0.1 fibers/cc.
• Based upon Table 4-15, it seems that EPA would
conclude that the few employees working in sheet
gasket stamping are not at any significant risk of harm.
In light of the background risk of cancer being
approximately 40%, historically, a risk to two workers
of 10-4 is trivial.
• Relying on the 1988 EPA risk assessment as a starting
point may be perilous. The 1988 EPA risk assessment
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for "asbestos" mixed studies of different fiber types,
and in so doing overestimated chrysotile risk by more
than an order of magnitude for both lung cancer
(Camus et al. (1998) and mesothelioma (Camus et al.
(2002; Case et al. (2002Y
• The risk involved in the continued use of chrysotile, in
limited products in which the fiber is encapsulated,
involving exposure to small numbers of people, is
small. The characterization as "unreasonably risky" is
hyperbole. The use of the TSCA machinery may be
clever, but the end results may bring consequences that
are unintended. Do substitutes exist that offer the same
level of safety to the worker and others as the proposed
reduction of risk following chrysotile exposure? EPA's
position and rationale for exposure reduction is not
supportable.
5.4 Use of inhalation volumetric adjustment factor
16, 34
PUBLIC COMMENTS:
• One commenter asked if it is appropriate to include an
inhalation volumetric adjustment factor in the equation
used to estimate cancer risk for workers; they had not
seen the use of a volumetric adjustment factor in that
kind of context.
• In the current Draft RE for Asbestos, the adjustment
factor for the different volumes of air inhaled by
workers and those environmentally exposed (step 3 of
the IUR process) is somewhat larger (3.04) in the
current Draft RE for Asbestos than in U.S. EPA (1986),
where an adjustment facto/r of 2.8 was used. This small
discrepancy arises from the fact that the original
adjustment assumed a 52-week work-year, whereas the
current Draft RE for Asbestos assumes a 50-week work-
year.
EPA routinely adjusts effects using a volumetric adjustment
factor that account for faster breathing in occupational
settings compared to non-occupational settings.
The IUR is for continuous, lifetime, exposure based on a
standard assumption of breathing 20 cubic meters of air per
day (equivalent to 6.67 cubic meters per 8 hours). In
applying the IUR to occupational scenarios, EPA adjusts the
risks to account for an assumption of an occupational
breathing rate of 10 cubic meters per 8 hours.
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5.5 EPA's approach for risk calculation
92
PUBLIC COMMENTS:
• Evaluating exposures to legacy asbestos separate from,
and on a different track than, its evaluation of
chrysotile exposures means that EPA will not look at
the full exposure potential workers face. For example,
workers can be exposed both at their job under current
COU, during repairs that involve legacy asbestos at a
facility, and when performing home renovations or
DIY brake repairs. Failure to consider the health effects
of legacy asbestos, alone or in combination with
chrysotile exposures, violates TSCA.
In Part 2 of the Risk Evaluation for Asbestos that will focus
on legacy uses and other fiber types, EPA will consider the
reasonably available information and use the best available
science to determine whether to consider aggregate or
exposures for asbestos and will include in that consideration
information from Part 1 and Part 2, as appropriate.
5.6 Clarity and validity of specific confidence summaries presented in Draft RE for Asbestos Section 4.3
SACC,
90,41
SACC COMMENTS:
• Although members of the SACC disagreed with some
of the conclusions reached, the assumptions, data gaps,
limitations, and other sources of uncertainty in the risk
characterization for workers were clear and easy to
follow. The sensitivity analysis was useful where it was
provided; the SACC recommended that sensitivity
analyses be done in other areas with data limitations.
The SACC recommended direct workplace visits to
understand the conditions of asbestos use for future risk
evaluations.
• The current sensitivity analysis within the Draft RE for
Asbestos was described by SACC members as more of
a "what-if' investigation. A true sensitivity analysis
would be facilitated via the use of Monte Carlo or
similar sampling simulations.
• Given the uncertainty around availability, use, and
effectiveness of appropriate respirator protection, some
SACC members recommended deleting the APF's in
the exposure estimates and risk calculations (remove
EPA appreciates the recognition from SACC that the
sensitivity analyses that were presented were clear, easy to
follow, and a strength in the risk evaluation. EPA tried to
provide examples, where possible, to show the impact of
several of the assumptions and uncertainties. However, full
probabilistic uncertainty analyses were beyond the scope of
this risk evaluation.
Following SACC recommendations, EPA's health risk
characterization is based on incidence of all cancers causally
related to asbestos exposure, and not just mortality from lung
cancer and mesothelioma (detailed in Appendix M).
The risk determination did consider non-cancer risks, and it
is important to point out that non-cancer risks are not limited
to deaths as the commenter suggests. While the commercial
chrysotile asbestos risk evaluation did not quantify non-
cancer risks, EPA recognizes that there are such risks and
has noted that the point of departure (POD) for the critical
non-cancer effect in the IRIS Toxicological Review of Libby
Amohibole asbestos (U.S. EPA (2014a) was 2.6E-2 fiber/cc
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from Table 4-55). Another member, however,
considered it appropriate to present risk with and
without PPE because there are industries and individual
facilities that comply with respiratory protection
protocols. Recommendation 61: Clarify in Table 4-55
that risks under PPE use are potentially unachievable
lower bounds that assume a comprehensive respiratory
protection program is always in place everywhere.
PUBLIC COMMENTS:
• While it would have been a seemingly straightforward
task, EPA made no attempt to validate their model (or
their risk characterization) based on the disease risk in
the populations of interest for the other COUs
evaluated. For example, despite using company-specific
data for their evaluation of risk in cohorts potentially
exposed to asbestos during the manufacturing and use
of gaskets, EPA did not attempt to determine if their
risk estimation accurately reflected the observed risks in
this population of workers.
• The Draft RE for Asbestos notes that the estimated
risks of death are conservative because they have not
considered non-neoplastic asbestos-related diseases in
their analysis. However, it "is well recognized" that
asbestosis reciuires exposure bevond a threshold (Scorn
and Rossli (2014; Rossli et al. (2010; Schneider et al.
(2010). There is no convincing evidence that the low
levels of exposure considered in the Draft RE for
Asbestos cause or contribute to any level of asbestosis,
let alone the levels that result in fatal pulmonary
fibrosis. With respect to benign asbestos-related pleural
diseases, only diffuse visceral pleural fibrosis has been
associated with mortality and then onlv rarelv (Manni
and Ourv (2014). There is no evidence that the level of
exposure considered in this document cause or
contribute to fatal diffuse visceral pleural fibrosis.
with a RfC of 9E-5 fiber/cc indicating that there can be
health risks at low concentration of fibers.
5.7 In-depth sensitivity analyses is a strength
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SACC
SACC COMMENTS:
• A strength of this section is the in-depth sensitivity
analyses presented in Appendices K and L that address
factors such as age at first exposure, and various
bystander scenarios. Many of the uncertainties need to
be better documented and judgments made about the
direction and magnitude of the bias that may result.
EPA appreciates SACC comments.
5.8 Uncertainties, limitations, and strength of the risk conclusions (Draft RE for Asbestos Section 4.3)
SACC,
42, 64,
64, 95,
42, 91
SACC COMMENTS:
• SACC raised several issues related to the assumption on
which the health risk characterization in the Draft RE
for Asbestos are based. These include restricting health
risks examined to only lung cancer and mesothelioma
mortality, calculating risks only for the chrysotile form
of asbestos, not considering legacy uses of asbestos, and
not accounting for aggregate exposures. These
assumptions and their impact on risk estimates should
be explicitly discussed in the risk characterization.
Several uncertainties as well as lack of data make it
difficult to evaluate the validity of the assessment of
exposure and the discussion on confounding presented
in the risk characterization section. Uncertainties with
exposure data could be addressed with sensitivity
analyses and with collection of more data.
• Consider the confidence in the risk estimate when it is
based on limited data. One SACC member suggested
using categorical descriptors of risk estimates (e.g, high,
medium, low) when data are limited or nonexistent.
Provide a short summary section on the analytical
methods used to quantify the various asbestos particle
types and sizes. Discuss how the analytical
Following SACC recommendations, EPA's health risk
characterization is based on incidence of all cancers causally
related to asbestos exposure, and not just mortality from lung
cancer and mesothelioma (detailed in Appendix M).
EPA will consider risks for legacy uses (and associated
disposal) and other fiber types of asbestos in Part 2 of the
Risk Evaluation for Asbestos.
Sensitivity analyses for exposure scenarios were conducted
and described in Appendix L. EPA did not believe that
collection of more data was necessary because there was
sufficient information reasonably available to complete Part
1 of the Risk Evaluation for Asbestos using a weight of
scientific evidence approach.
EPA believes it is important to use a consistent approach for
risk characterization and risk determination. Categorical
descriptors for risk estimates have not been used in risk
evaluations under TSCA, and it would take substantial effort
to develop criteria for categorical descriptors and the benefit
is unclear to EPA. Asbestos particle sizes and analytical
methodology have been described where necessary. Study
quality criteria is described in Supplemental Files for Part 1
of, which also include evaluations for each of the relevant
studies.
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methodology has evolved over time and how that might
impact study quality assessment.
• In the risk characterization for environmental exposures,
as the SACC has seen in previous chemical Draft REs,
there is limited discussion of uncertainties and typically
"worst-case" scenarios that are not considered. To be
conservative, the Draft RE for Asbestos should favor
"worst-case" risk estimates for low/no data COUs until
the necessary data are obtained. Recommendation 96:
Data gaps and related uncertainties should be discussed
and have greater weight in the Risk Characterization
sections.
• Recommendation 97: Define the minimal
data/information needed to produce a reliable and
confident estimate of risk.
PUBLIC COMMENTS:
• While the commenters agree that EPA should give
serious consideration to the "... the strengths,
limitations, and uncertainties associated with the
information used to inform the risk estimate and the
risk characterization," an enormous amount of
uncertainty is not discussed. In particular, the enormous
degree of uncertainty regarding lung cancer and
mesothelioma cancer potency factors used for
chrysotile is not adequately disclosed.
Section 4.3.6 in Part 1 of the Risk Evaluation for Asbestos
details key assumptions and uncertainties related to cancer
risk values. EPA believes that these uncertainties are
appropriately considered in drawing conclusions but did
elaborate and expand upon biases in Appendix H. EPA did
not identify any data gaps that would preclude a reasoned
analysis for Part 1 of the Risk Evaluation.
TSCA does not contemplate development and submission of
a "minimum data set" before risks can be assessed; rather
EPA assessments under TSCA are fit-for-purpose. As noted
by the commenter, TSCA provides EPA authority to require
development of information, where necessary. However,
EPA had sufficient information to complete the chrysotile
asbestos risk evaluation using a weight of scientific evidence
approach. EPA selected the first 10 chemicals for risk
evaluation based, in part, on its assessment that these
chemicals could be assessed without the need for regulatory
information collection or development. When preparing this
risk evaluation, EPA obtained and considered reasonably
available information, defined as information that EPA
possesses, or can reasonably obtain and synthesize for use in
risk evaluations, considering the deadlines for completing
the evaluation.
With regard to uncertainty, EPA evaluates the quality of the
data cited in sources using data quality metrics and data
evaluation scoring described in the Application of Systematic
Review in TSCA Risk Evaluations. These include metrics that
are designed to take the QC processes and overall quality of
sources into account when assessing the quality of the data.
The data quality criteria also specifically identify what flaws
in particular data sources would render a data source
unacceptable.
If no applicable monitoring data were identified, exposure
scenarios were assessed using a modeling approach that
requires the input of various chemical parameters and
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exposure factors. When possible, default model input
parameters were modified based on chemical-specific inputs
available in literature databases.
5.9 Significant digits
16
PUBLIC COMMENTS:
• In characterizing risk, how many significant digits
should be used to present cancer risk estimates?
EPA traditionally presents IUR with two significant digits
(US EPA, 1986, 2014).
5.10 Concerns about risk estimate benchmark for workers
42, 85
PUBLIC COMMENTS:
• One commenter stated that he has never seen an
occupational assessment where a cancer risk of 3.5 E-04
cancer risk for two to four employees is considered
unacceptable.
• EPA should consider the number of persons who are
likely to be exposed when determining whether an
exposure scenario "indicates unreasonable risk" rather
than simply comparing risk estimates to the 10-4 or 10-
6 benchmarks irrespective of the number of people who
might be exposed. In several of the COU exposure
scenarios, particularly involving
brakes/clutches/gaskets, no more than a handful of
people could be exposed in the future.
• EPA's Draft RE for Asbestos "accepts far greater risks
to workers than to consumers and other members of the
general public" by using the benchmark of 10"4 for
workers and 10"6 for the public. The commenter did not
see a valid reason for EPA to accept such high risks to
workers.
• EPA cited NIOSH guidance; however, NIOSH is not
required to set risk management limits for carcinogens
at a level that avoids unreasonable risk to potentially
exposed and susceptible subpopulations. Further, the
commenter cites NIOSH 2017 policy that the excess
Under TSCA, EPA does not need to consider the number of
exposed individuals to reach a determination of unreasonable
risk to health. EPA considered a variety of factors as part of
its risk determinations for the chrysotile asbestos conditions
of use including exceedances of the risk benchmarks, the
physical-chemical properties of asbestos and the severe and
irreversible health effects associated with asbestos
inhalation.
EPA relied on Agency precedent and NIOSH guidance
(Whittaker et al., 2016) when choosing the 10-4 cancer risk
benchmark to evaluate risks to workers from chrysotile
asbestos exposure. NIOSH's mandate, on pg iii of Whittaker
et al. (2016), is to: "... describe exposure levels that are safe
for various periods of employment, including but not limited
to exposure levels at which no employee will suffer impaired
health or functional capacities or diminished life expectancy
as a result of his work experience." Although NIOSH
guidance, p. 20, states that: "exposures should be kept below
a risk level of 1 in 10,000, if practical [emphasis added]"
EPA adheres to the 1 in 10,000 benchmark during the risk
evaluation stage for TSCA chemicals.
The standard cancer benchmarks used by EPA and other
regulatory agencies range from 1 in 1,000,000 to 1 in 10,000
(i.e., lxlO"6 to lxlO"4) depending on the subpopulation
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lifetime risk level of 1 in 10,000 is considered to be a
starting point for continually reducing exposures in
order to reduce the remaining risk and that NIOSH will
continue to recommend reducing exposure to
carcinogens as much as possible through the hierarchy
of controls (Whittaker (2017).
• EPA cited Indus. Union Dep't, AFL-CIO v. American
Petroleum Inst., 448 U.S. 607 (1980) (the "Benzene
decision"). That decision interprets the Occupational
Safety & Health Act, and it has no bearing on EPA's
duty to identify and manage unreasonable risks under
TSCA.
exposed. EPA has consistently applied a cancer risk
benchmark of lxlO"4 for assessment of occupational
scenarios under TSCA. This is in contrast with cancer risk
assessments for consumers or the general population, for
which lxlO"6 is applied as a benchmark.
EPA, consistent with 2017 NIOSH guidance, used lxlO"4 as
the benchmark for the purposes of unreasonable risk
determinations for individuals exposed to chrysotile asbestos
in industrial and commercial work environments, including
workers and ONUs. lxlO"4 is not a bright line and EPA has
discretion to make unreasonable risk determinations based
on other benchmarks as appropriate. See Section 5.1.2 of the
risk evaluation for additional information
EPA has removed reference to Indus. Union Dep't, AFL-
CIO v. American Petroleum Inst., 448 U.S. 607 (1980) (the
"Benzene decision"). TSCA compels EPA to evaluate
chemicals without consideration of non-risk factors (such as
feasibility of meeting a standard) to determine whether they
present unreasonable risk under the conditions of use. EPA's
"no unreasonable risk" standard has not necessarily been met
at the OSHA PEL.
5.11 An asbestos ban is not needed under TSCA
42
PUBLIC COMMENTS:
• EPA should discuss somewhere in the Draft RE for
Asbestos that in 2018, EPA decided that a ban on
imported asbestos was not necessary at that time.
• One expert on asbestos concluded that given possible
sources of asbestos exposure, number of people
potentially exposed, and current U.S. regulations
regarding environmental and worker protection and
EPA did not determine that a ban on imported asbestos was
not necessary in 2018. As required by the Lautenberg
amendments to TSCA, and following EPA's designation of
asbestos as one of the first 10 chemicals to undergo risk
evaluation, EPA must first evaluate the risks posed by
asbestos. Following completion of the risk evaluation, the
Agency must pursue risk management for any COUs
determined to pose unreasonable risk to health or the
environment. Therefore, upon finalization of the Asbestos
Risk Evaluation (Part 1: Chrysotile Asbestos), EPA will
pursue risk management for the COUs that pose
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imports of asbestos-containing materials are adequate;
an asbestos "ban" under TSCA is not needed.
• If there are a handful of applications in essential
industries that require the importation of a limited
number of asbestos-containing gaskets or packing to
produce militarily or economically crucial goods, EPA
could ban the importation of asbestos, except for these
special applications.
unreasonable risk to health or the environment. Risk
management options provided under TSCA 6(a) include, but
are not limited to, a prohibition on commercial use.
EPA will also evaluate legacy uses of asbestos in Part 2 of
the Risk Evaluation for Asbestos, beginning with a draft
scope document. If unreasonable risk to health or the
environment is found for any of the legacy asbestos COUs,
EPA will pursue risk management for those COUs.
5.12 Asbestos should be banned under TSCA
25, 27,
31,45,
47, 68,
85, 86,
89, 92,
101,
111
PUBLIC COMMENTS:
• Several commenters recommended that EPA use its
authority under TSCA to completely ban asbestos uses
and imports as soon as possible.
• Since December 2016 when EPA announced that
asbestos would be one of the first 10 chemicals for risk
evaluation, EPA has received public comments in four
unique dockets. They contain over 175,000 comments
and petition signatures. The commonalities in all of this
public input is:
- Asbestos is a known carcinogen.
- There is no safe level of exposure to asbestos.
- The Significant New Use Rule (SNUR) would not
ban existing and future imports and use.
- Asbestos imports and use must end.
- Legacy asbestos is a great danger in homes,
schools, and workplaces.
• One commenter summarized some of the reasons they
consider the Draft RE for Asbestos to underestimate
true risks from exposure to asbestos for those whom the
EPA is obliged to protect:
- It sets aside the decades-old linear dose-response
risk model that is supported by sound scientific
As required by the Lautenberg amendments to TSCA, and
following EPA's designation of asbestos as one of the first
10 chemicals to undergo risk evaluation, EPA must first
evaluate the risks posed by asbestos. Following completion
of the risk evaluation, the Agency must pursue risk
management for any COUs determined to pose unreasonable
risk to health or the environment. Therefore, upon
finalization of the Asbestos Risk Evaluation (Part 1:
Chrysotile Asbestos), EPA will pursue risk management for
the COUs that pose unreasonable risk to health or the
environment. Risk management options provided under
TSCA 6(a) include, but are not limited to, a prohibition on
commercial use.
EPA will also evaluate legacy uses of asbestos in Part 2 of
the Risk Evaluation for Asbestos, beginning with a draft
scope document. If unreasonable risk to health or the
environment is found for any of the legacy asbestos COUs,
EPA will pursue risk management for those COUs.
Regulatory actions to address unreasonable risks are outside
the scope of the risk evaluation process.
EPA did not set aside linear model. EPA considered and
used linear model in derivation of IUR.
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evidence, and protective of the public health,
without evidence that the exponential risk model
chosen is better.
- Among the six asbestos fiber types in commercial
use, the Draft RE for Asbestos considers only one.
- Two of the four cancers recognized by IARC as
asbestos-related are ignored
- Nonmalignant disease is ignored.
- Legacy asbestos, a particular risk in public schools,
is set aside for another and uncertain day.
• Under these circumstances, the only option for
protection from unreasonable risk of injury to health
from continued exposure to asbestos in the US is a
federal ban on asbestos.
• A blanket ban on asbestos with strict regulations about
the continued use of legacy materials, much like
TSCA's approach to PCBs is needed. EPA's final
evaluation should reverse the conclusions of the draft
and determine that all importation, distribution in
commerce and disposal of asbestos presents an
unreasonable risk of injury.
• Rather than allow for (even with restrictions) any new
uses for asbestos, EPA should seek to ban all new uses
of asbestos because there are adequate alternatives to
asbestos. (See original Attachment 2 for a screen shot
of the website change.org with the title "Ban Asbestos
in the US Now, Without Loopholes or Exemptions."
• Other countries have banned asbestos. As of March
2019, 66 countries have banned the use of asbestos,
including all members of the European Union, but not
the US. An additional 10 nations are placing
restrictions on its use. These include many developed
countries that have banned import or use of asbestos.
Brazil, who as recently as 2017 supplied most of the
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chrysotile for use in the US chlor-alkali industry also
voted for a ban in November of 2017. Others offered
essentially the same observations on bans by other
countries.
5.13 Previous TSCA legislation
PUBLIC COMMENTS:
• Mixed results have occurred when EPA has attempted
to mitigate risk to asbestos under Toxic Substances
Control Act (TSCA). EPA promulgated the Asbestos
Ban and Phase Out Rule (ABPR) in 1989, but industry
won; the Fifth Circuit Court of Appeals overturned the
ban. Since 1989, the US has consumed nearly 400,000
metric tons of asbestos and buried one million
Americans.
• The 2016 TSCA amendments were enacted in part
because of frustration with EPA's inability to regulate
asbestos.
• In April 2019, EPA finalized an Asbestos Significant
New Use Rule (SNUR) under TSCA Section 5, which
does not represent a permanent ban. The SNUR can
track but not ban the reintroduction of discontinued
asbestos products. Thus, under the SNUR, the
possibility exists that importing, processing or
manufacturing as well as discontinued uses could be
approved in the future; it therefore does not protect
persons from exposure to asbestos and associated risks
of injury or death. Given the significant number of
asbestos sites that EPA has to clean up due to improper
disposal or abandonment, opening the door to new uses
of asbestos is not an economically wise or health-
protective idea.
EPA acknowledges the commenters' opinions. EPA clarifies
that the SNUR is a restrictive rule prohibiting the
discontinued uses of asbestos from restarting without EPA's
review and evaluation of each intended use (i.e., significant
new use) for potential risks to health and the environment
and any necessary regulatory action, which may include a
prohibition. The SNUR does not provide a means by which
prohibited uses under the 1989 partial ban under TSCA
Section 6 could return to the marketplace.
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5.14 Include a "mobile app" for users to calculate risk
SACC
SACC COMMENTS:
• The SACC recommended that this (and other TSCA)
risk evaluations would benefit from creation of a
"mobile app" that would ease communication of these
risk findings to risk managers. A "mobile app" might
also allow a user to calculate risk from a specified
exposure scenario in which he/she is interested. Such
an "app" would have KL and KM hardwired in, and
have options for selecting the COUs, full shift or ONU
workers, level of exposure (central tendency or high-
end), APF (0, 10 or 25), with the user able to select the
age at which exposure begins and the duration of that
exposure. Other options that allow the user to compute
the risk from scenarios not considered in the risk
evaluation (such as different exposure levels or time-
varying exposures) could be included. The "mobile
app" could serve as a useful adjunct to the risk tables
currently in the RE or possibly as a partial replacement.
• Recommendation 66: Consider creating an "app" to
make it easier for readers to digest and use the
information presented in Table 4.2 to Table 4.38.
EPA thanks the commenter for this suggestion but planning
or development of a "mobile app" is outside the scope of
EPA's Risk Evaluation for Asbestos.
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6. Environmental Risk Characterization and Determination
EPA did not include a charge question specific to environmental risk characterization and determination, but SACC and public
comments addressed these topics.
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6.1 Overarching comments on environmental risk characterization
SACC,
31
SACC COMMENTS:
• SACC noted uncertainties with respect to environmental
exposure that limit conclusions that can be drawn and
that require additional explanation, including the
inconsistency between lack of data regarding potential
asbestos release into water, and determination of no
unreasonable risk to aquatic organisms. The reliance on a
macrophage mechanism of action raises concerns of
asbestos exposures for longer-lived species.
• Recommendation 76: Add explicit uncertainty discussion
and explanation for environmental exposures.
PUBLIC COMMENTS:
• One commenter concurs, in general, with EPA's overall
draft assessment of risk posed by chrysotile asbestos to
the natural environment.
EPA added an acknowledgement of uncertainty in Section
2.2.2.1 regarding releases from chlor-alkali facilities.
However, EPA believes uncertainty is low and that there is
minimal risk posed to aquatic species. Generally, the
conclusions made in Part lof the Risk Evaluation for
Asbestos for environmental exposure and aquatic species are
based on reasonably available information on chrysotile
asbestos releases to surface waters identified and evaluated
under EPA's systematic review process which shows little to
no evidence of releases of asbestos to surface water
associated with the COUs that EPA is evaluating in Part 1.
Additionally, no releases were identified or reported to
EPA's TRI for COU's evaluated in Part 1 of the Risk
Evaluation for Asbestos. Therefore, the conclusion of little to
no exposure (and therefore no unreasonable risk) is based on
little to no releases to the environment (surface water) which,
in turn would indicate little to no exposure (and associated
effects) to aquatic species resulting from chrysotile asbestos.
If exposure does not occur, then there would be no
unreasonable risk to aquatic species.
6.2 Risk to aquatic species not adequately evaluated
SACC
SACC COMMENTS:
• The hazard sections for environmental effects are
relatively well presented with a weight of evidence
section. However, the precise selection of studies is not
conveyed in the Environmental Hazard section (Section
3.1) nor is an adequate justification provided for why
toxicity data ranges by four orders of magnitude.
The reasonably available information for each chemical
substance allowed EPA to complete the risk evaluation and
determine whether the chemical substance presented an
unreasonable risk under the COUs. In some cases, when
information available to EPA was limited, the Agency relied
on models; the use of modeled data is in line with EPA's
final Risk Evaluation Rule and EPA's risk assessment
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Selecting one or two specific studies to be representative
of effects to all aquatic organisms (i.e., the critical study
approach) presents the appearance of bias.
• Recommendation 100: Present the available aciuatic
toxicity data graphically, include results from studies of
low quality, and particularly results from studies that
examine receptors not otherwise considered in the
evaluation.
• The SACC concluded that the Draft RE for Asbestos
does not adequately evaluate the risk to aquatic species
from exposure to surface water. It was unclear how EPA
could come to this conclusion without measured or
predicted concentrations that could be compared to
hazard values.
• Asbestos "releases from chlor-alkali facility treatment
systems to surface water and POTW are not known," and
while the chlor-alkali filtering treatment is expected to
capture asbestos solids, its specific efficiency is
unknown (Draft RE for Asbestos p. 53). In view of this,
it is not clear how the Draft RE for Asbestos can make a
determination "of no exposure regarding potential
releases to water for the COU's in this evaluation" (page
194) and "no unreasonable risk to aquatic.. .organisms"
(page 207). An additional concern was expressed
regarding the conclusion (Section 4.5.1) of basing a risk
determination of no environmental risk on a lack of
"reported" exposure data. Determinations of risk should
be based on measured data rather than "expectation
and/or lack of identification."
• Recommendation 75: Limit environmental risk
determinations to scenarios/COUs that have available
actual exposure data.
guidelines. EPA did not use its TSCA data collection
authorities to gather additional information for this chemical
because EPA believes it has sufficient information to make a
reasoned analysis and in light of the limited time available
under the statute for completing the risk evaluation. In the
future, EPA will have additional time prior to risk evaluation
to evaluate data needs and judge whether testing or chemical
specific data collection is appropriate.
EPA thanks SACC for the recommendations and will
consider a graphical representation of aquatic toxicity data in
the supplement asbestos document.
As stated in the PF, EPA evaluated reasonably available
information while focusing on the possible presence of
asbestos in water for exposure to aquatic organisms. After
the PF, it was determined that while there are releases of
asbestos to surface waters, not all releases are subject to
reporting (e.g, effluent guidelines) or are applicable (e.g,
friability). Based on the reasonably available information,
including published literature, EPA databases, and provided
by industry, there is minimal or no releases of asbestos to
surface water and sediments associated with the COUs in
this document and therefore , EPA concludes in Part 1 of the
Risk Evaluation for Asbestos there is no unreasonable risk to
aquatic or sediment-dwelling organisms from the evaluated
COUs.
Chlor-alkali facilities are not required to monitor effluents
for asbestos releases and TRI reporting is not required for
other forms of asbestos (e.g, non-friable asbestos, asbestos in
aciueous solutions) (U.S. EPA (2017b).
6.3 Limitations of EPA's conclusions
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SACC,
105
SACC COMMENTS:
• The title for Section 3.1 is "Environmental Hazards."
The SACC noted that the term "environmental hazards"
has broad interpretation and could be construed as
including all hazards, either directly or indirectly
affecting any organism, resulting from an exposure
because of an environmental release. The contents of
Section 3.1 suggest a narrower definition since this
section only refers to direct effects to non-human
receptors (better described as "ecotoxicity" or "hazards
to environmental receptors"). EPA should consider
renaming these sections more specifically.
• Recommendation 99: Rename Section 3.1
Environmental Hazards to be either "Hazards to
Environmental Receptors" or "Ecotoxicity."
PUBLIC COMMENTS:
• EPA rated Zebedeo et al. (2014) (low-dose mouse
injection study) as irrelevant to ecologic risks, unlike all
other injection experiments that EPA rated relevant. EPA
also classified as irrelevant to both human and ecologic
risk another low dose immunotoxicity experimental
finding from another lab (Pfau et al. (2008).
EPA acknowledges this comment. The title of Section 3.1
will remain "Environmental Hazards" for consistency across
TSCA risk evaluations.
For human health, Part 1 of the Risk Evaluation included a
limited range of outcomes including lung cancer,
mesothelioma. Zebedeo et al. (2014) and Pfau et al. (2014)
were both identified by EPA but did not meet criteria for
ultimate inclusion for hazard identification.
6.4 Alternative approaches for surface water scenarios
SACC
SACC COMMENTS:
• In lieu of monitoring data, EPA should either make a
statement that risk cannot be evaluated or use surface
water measurements as a "worst-case" scenario for
comparison to concentrations of concern (COC).
• The available information in the Problem Formulation
reoort (U.S. EPA (2018) indicated that there were surface
water releases of asbestos; however, not all releases
were subject to reporting (e.g, effluent guidelines) or
were applicable (e.g, friability). The Draft RE for
EPA did not use surface water measurements as a "worst-
case" scenario for comparison to COCs because these
concentrations cannot be attributed to COUs included in Part
1 of the Risk Evaluation for Asbestos focused on chrysotile
asbestos. Surface water measurements and environmental
releases will be further considered in Part 2 of the Risk
Evaluation for Asbestos (legacy uses and other fiber types of
asbestos).
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Asbestos reported asbestos levels in drinking water,
which led several SACC members to comment that
surface water concentrations are thus likely to be higher.
One SACC member wondered why these data were
even considered, since surface waters were the intended
target for the assessment. EPA could consider (1) doing
a system-wide assessment of asbestos in surface or
drinking waters as a way of assessing total asbestos
releases (2) estimating surface water concentrations
based on removal of fibers during the process of
converting raw to finished water during treatment.
6.5 Discuss uncertainties about concentrations of asbestos in effluent
SACC
SACC COMMENTS:
• The SACC appreciated the efforts that EPA provided to
assess COU-associated surface water discharges using
available data. Evaluations of TRI data indicated zero
discharge to POTWs and non-POTW facilities from
COUs targeted in the Draft RE for Asbestos. Statements
from the Problem Formulation of the Risk Evaluation of
Asbestos reoort (U.S. EPA (2018) indicated that the
chlor-alkali industry in years prior to 2017 did discharge
chrysotile-asbestos to wastewater. The Draft RE for
Asbestos indicates that following visits to these facilities
in late 2017, follow-up evaluations were conducted. The
Draft RE for Asbestos noted that chlor-alkali facilities
are not required to monitor asbestos through NPDES.
The Draft RE for Asbestos concludes that water
discharges were zero in 2018. It was unclear to SACC
members how a conclusion of zero discharge was made
without measurements. It was also unclear why EPA did
not request these facilities to provide discharge
monitoring data after its initial scoping exercise in 2016
(U.S. EPA (2017a). (SACC-31)
EPA clarifies that a conclusion of zero discharge is not
made, but rather Part 1 of the Risk Evaluation states that
"there were minimal or no releases of asbestos to surface
water associated with the COUs that EPA is evaluating"
(Section 2.2.3) in Part 1 of the Risk Evaluation for Asbestos.
EPA did not request the development of new data from
facilities because EPA believes it had sufficient information
to complete the Part 1 of the Risk Evaluation for Asbestos
using a weight of scientific evidence approach.
EPA investigated industry sector, facility, operational, and
permit information regulated by NPDES under the Clean
Water Act to identify any permit limits, monitoring and
reporting requirements, and any discharge provisions related
to asbestos and its COU, as stated in Appendix D. EPA
identified NPDES permits for facilities that may release
asbestos (chlor-alkali and sheet gasket facilities), and most
chlor-alkali facilities have issued NPDES permits for
industrial operations and general stormwater projects; none
of the NPDES limits/monitoring requirements contained
asbestos or asbestos-related parameters codes or any direct
effluent screening information for asbestos.
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• SACC noted additional uncertainties related to water
discharge, specifically the lack of measurements of
chrysotile fibers in surface waters associated with the
targeted COUs. Monitoring data of surface waters
clearly show the occurrence of fibers in surface waters
(Belanser et al. 0986). Conseciuentlv, there is a
disconnect between the Problem Formulation document
(U.S. EPA (2008) indicating specific COUs (chlor-
alkali) discharge waste to POTWs and the Draft RE for
Asbestos conclusion of no discharge based on a lack of
monitoring data for POTWs which are not required to
monitor asbestos. Friable chrysotile asbestos is filtered
during the COU for the chlor-alkali industry. The Draft
RE for Asbestos does not report the mesh-size of the
filter, which is critical as fiber length may have
significant impact on biological responses. Additional
uncertainty for water discharge is also present with other
COUs, including brake dust cleanup. During brake pad
replacement, compressed air is used to clean dust which
typically would settle to the surface of the areas where
the cleaning or replacement occurs. If these events occur
within residential areas during consumer use, these
surfaces are largely watered down with the resulting
waste transported into POTWs or stormwater basins.
This pathway was not addressed in conceptual models
for the Scope nor Problem Formulation.
• Recommendation 80: Discuss the uncertainty related to
potential releases of asbestos in water discharged to
POTWS or stormwater basins as a result of brake dust
cleanup.
In Section 2.2.2.1, EPA included the following text related to
uncertainty for the presence of asbestos in stormwater or
POTWS from chlor-alkali facilities: "While the treatment
technologies employed would be expected to capture
asbestos solids, the precise treatment efficiency is not
known." EPA acknowledges the uncertainty associated with
the various mesh filters used by these facilities. Asbestos
fibers, due to their structure, should collect in the mesh
filters following the discharge from facilities to wastewater.
TRI does not indicate discharges to surface water, chlor-
alkali facilities do not indicate releases after treatment.
While EPA acknowledges that use of compressed air to clean
dust during a brake pad replacement can result in a settling
of chrysotile asbestos fibers that may collect in stormwater
basins, EPA believes the concentrations of fibers that could
results from this scenario would be minimal.
6.6 Action is needed to require measurement of asbestos in effluent
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31
PUBLIC COMMENTS:
• One commenter requested that EPA amend their effluent
guidelines to require measurement of asbestos in
effluents of relevant industries and to set specific limits
for asbestos from those operations where discharges are
allowed.
• For certain asbestos manufacturing operations, EPA
reported (Draft RE for Asbestos In. 1815-1819) that
their effluent guidelines establish limits on the allowable
levels of TSS, pH, or COD). However, the regulations do
not establish specific limits for asbestos from those
operations where asbestos discharges are allowed. Thus,
without the requirement to measure asbestos
concentrations in effluent, estimating asbestos levels in
effluent or receiving waters is challenging. The
commenter strongly recommended that EPA amend their
effluent guidelines to require that (1) concentrations of
asbestos in effluent be measured, and (2) specific limits
be established for asbestos from those operations where
discharges are allowed.
These comments are sufficiently addressed by newly added
text in Section 1.4.4. EPA appreciates the suggestion to
amend effluent guidelines. The Clean Water Act (CWA)
publishes recommended criteria for priority pollutants,
requiring NPDES discharge permits to include stringent
discharge limits. EPA has not developed CWA section
304(a) recommended water quality criteria for the protection
of aquatic life for asbestos, so there are no national
recommended criteria for this use available for adoption into
state water quality standards and available for use in NPDES
permits. The CWA and NPDES permitting guidelines are the
legal mechanisms to require effluent guidelines in the US.
6.7 Environmental risk determination
SACC
SACC COMMENTS:
• Several SACC members noted that the Risk
Determination section for environmental risk concludes
"low or no potential for environmental risk to aquatic
receptors" based on the observation (assumption?) that
water releases associated with the COUs are not
expected and were not identified. The SACC suggested
that a more appropriate determination would be to
conclude that "environmental risk could not be
This statement has been added to the Risk Determination,
Section 5.1.3, for clarity, "environmental risk could not be
ascertained."
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ascertained," because water releases associated with the
COUs are not expected and were not identified.
• Recommendation 101: Because water releases associated
with the environmental COUs while not expected are not
actually assessed, the decision on environmental risk
should be stated as "environmental risk could not be
ascertained."
7. Potentially Exposed or Susceptible Subpopulations
Charge Question 6:
6.1 Has a thorough and transparent review of the available information been conducted that has led to the identification and
characterization of all PESS (Sections 2.3.3, 3.2.5., and 4.4.1)? Do you know of additional information about PESS that EPA needs to
consider? Additionally, has the uncertainty around PESS been adequately characterized?
6.2 Please comment on whether EPA has adequately, clearly, and appropriately presented the reasoning, approach, assumptions, and
uncertainties for characterizing risk to workers using PPE (exposure - Sections 2.3.1.2.; risk Section 4.2.1 and Tables 4-3 and 4-38).
6.3 Please comment on whether EPA has adequately, clearly, and appropriately presented the reasoning, approach, assumptions, and
uncertainties for characterizing risk to ONUs who would not be expected to use PPE (Sections 4.2.1 and 4.3.7).
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7.1 Differentiate risk estimates for smokers and nonsmokers
SACC
SACC COMMENTS:
• Recommendation 58: Revise risk estimates and tables to
provide separate risk estimates for smokers and
nonsmokers. There's evidence for a synergistic
relationship between smoking and asbestos in causing
lung cancer. The IUR was derived based on mortality
data containing both smokers and nonsmokers, which
EPA searched the CDC Wonder and SEER databases for
cancer statistics on smokers and did not find data on rates for
smokers. Higher background rates of lung cancer among
smokers would be expected to be associated with higher
values of the IUR and thus higher risks. The data necessary
for lifetables were also not available for other PESS groups.
Therefore, EPA was not able to follow this SACC
recommendation based on the timeframe and reasonably
available information.
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should be revised to distinguish background risks for
smokers and nonsmokers.
• The Draft RE for Asbestos discusses some susceptible
subpopulations but does not fully discuss incorporation
of these vulnerabilities into risk assessments. For
example, smokers should have different and distinct risk
calculations given that the combined effect of both
asbestos exposure and smoking is most likely supra-
additive. The Draft RE for Asbestos correctly identifies
cigarette smokers as a susceptible subpopulation for the
effects of asbestos exposure.
7.2 Address population with underlying health conditions
SACC,
42,51,
92
SACC COMMENTS:
• The SACC considered workers who smoke cigarettes a
susceptible subpopulation when it comes to lung cancer.
Workers, ONUs, and DIY-exposed individuals who
have chronic lung disease, including chronic obstructive
lung disease and pulmonary fibrosis, have an elevated
risk of lung cancer and form a susceptible population.
Recommendation 82: Discuss how the increment in
exposure associated with the COUs may cause
individuals with early-stage lung disease or pulmonary
fibrosis to exceed the designated targets of unreasonable
risk.
• Recommendation 83: Add quantitative estimates of the
added risk of cancer from exposure to asbestos for the
following susceptible subgroups: smokers, individuals
who have chronic lung disease, including chronic
obstructive lung disease and pulmonary fibrosis, and
other individuals having an elevated risk of lung cancer.
Quantifying the extra cancer risk in smokers due to
exposure to asbestos can be accomplished by applying
the already-calculated KL and KM in a life table
EPA was not able to identify reasonably available
information in the timeframe for completing Part 1 of the
Risk Evaluation that would allow for quantitative
consideration of some susceptible populations, including
smokers and those with early-stage lung disease.
Accordingly, EPA was unable to update life tables using
methods to characterize smokers explicitly. However, EPA
notes qualitatively that, if the underlying PESS conditions
increased the condition-specific background risk of incident
lung cancer, this would be expected to decrease the exposure
concentration needed to increase the extra risk of lung cancer
by 1% and increase the IUR for that PESS condition.
In Section 3.2.4, EPA describes that there "some evidence of
genetic predisposition for mesothelioma related to having a
germline mutation in BAP1EPA has not included an
extensive description of the evidence because it would not be
feasible to estimate the size of the potentially susceptible
population for the purposes of refining risk determination.
Furthermore, EPA used high-end risk estimates to account
for PESS that could not be quantified.
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analysis that uses background rates of lung cancer and
death from all causes that apply to smokers.
• Recommendation 45: Use life table methods to estimate
lung cancer risks separately for workers exposed to
asbestos who also smoke.
• Recommendation 85: Discuss how the science related to
asbestos risk and BAP1 or related mutations is
insufficient at this time to define individuals having
these mutations as a PESS.
PUBLIC COMMENTS:
• Though a synergistic relationship for lung cancer risk
between asbestos exposure and smoking has been
demonstrated in some studies of cohorts exposed to
high cumulative asbestos exposure levels, there is no
evidence that this relationship exists at low cumulative
asbestos exposure levels, such as those experienced by a
career automobile mechanics.
• EPA's risk evaluation fails to address individuals
exposed to asbestos across multiple routes and pathways
and persons at increased risk such as cigarette smokers
and individuals with underlying lung disease.
EPA considered the reasonably available information and
used the best available science to determine whether to
consider aggregate exposures for chrysotile asbestos. EPA
determined that using the high-end risk estimate for
inhalation risks separately as the basis for the unreasonable
risk determination is a best available science approach. There
is low confidence in the result of aggregating inhalation risks
for this chemical if EPA uses an additive approach, due to
the uncertainty in the data. EPA does not have data that
could be reliably modeled into the aggregate, which would
be a more accurate approach than adding, such as through a
PBPK model. Using an additive approach to aggregate risk
in this case would result in an overestimate of risk.
7.3 Consider aggregate exposures and multiple pathways when defining PESS
51
PUBLIC COMMENTS:
• Aggregate exposures for asbestos were not assessed by
routes of exposure, since only inhalation exposure was
evaluated in the Draft RE for Asbestos. EPA chose not
to employ simple additivity of exposure pathways at
this time within a COU because of the uncertainties
present in the current exposure estimation procedures.
This lack of aggregation may lead to an underestimate
As the commenter states, EPA articulated the reasons for
which aggregated exposures by routes of exposure for
chrysotile asbestos were not assessed. EPA has the most
confidence in evidence for cancer resulting from inhalation
exposures. In Section 4.4.2, EPA does acknowledge that
there is the potential for underestimating risks that may result
from other routes of exposure, but the additional cancer risk
is expected to be minimal. Furthermore, EPA discussed
factors that could contribute to increased susceptibility,
including physiological factors and potential for increased
exposure, but there was not data reasonably available to
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of exposure but based on physical chemical properties
most of the exposure is believed to be from inhalation.
• Risks are understated because Draft RE for Asbestos
does not account for increased risks to subpopulations
with greater susceptibility to asbestos or multiple
pathways of exposure.
quantitively consider additional risk with sufficient
confidence.
7.4 Consider firefighters, teachers, contractors not covered by OSHA
15, 50,
51,73,
81, 92
PUBLIC COMMENTS:
• By amending TSCA in 2016, Congress also
acknowledged that existing protections for workers
from chemical hazards are inadequate, including
exposure to asbestos. More than 8 million workers are
not covered by the OSH Act, including 8 million public
sector workers, such as firefighters and the
professionals who work in schools and for government
agencies. Others who are not covered by the OSH Act
include the 15 million people who are independent
contractors or otherwise self-employed, and agricultural
workers on small farms.
• The Draft RE for Asbestos specifically ignores legacy
use exposures to firefighters. The 2013 NIOSH study
found higher rate of mesothelioma in firefighters and
likely linked these findings to exposure to asbestos.
Since asbestos fibers are known to be released during
fire, firefighters are under high exposure to these fibers
when extinguishing fires. Therefore, firefighters should
be considered as a susceptible population given the high
risk of exposure.
• Emergency response crews and volunteers (as well as
building occupants) are at high risk of legacy asbestos
exposure in the wake of fires and other disasters. Where
the duration of exposure is prolonged and more
exposure events occur, the risk of asbestos-related
EPA acknowledges the potential for these additional
populations to be exposed to asbestos. However, Part 1 of
the Risk Evaluation for Asbestos focused on COUs and
exposures relevant to chrysotile asbestos. EPA will consider
legacy uses and related exposures, both occupation and
general population, in Part 2 of the Risk Evaluation for
Asbestos (legacy uses and other fiber types of asbestos).
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disease is increased (Bianchi and Bianchi (2007). A
well-studied disaster resulting in widespread asbestos
release was the 2001 attack on the New York World
Trade Center (WTO (Landrisan et al. (2004).
• The Draft RE for Asbestos ignores exposures to
workers, visitors, students, and teachers who can be
present for extended periods (30-40 hours per week) in
asbestos-containing buildings and schools. Asbestos can
be released during building upkeep and maintenance or
from damaged and poorly maintained building
components. The City of Philadelphia provided an
example of the hazards posed by asbestos-containing
insulation in public schools and illustrates the
importance of consideration of amphibole fibers for
asbestos risk (Graham and Ruderman (2020).
7.5 Consider tribal communities
SACC,
88
SACC COMMENTS:
• The health disparities in American Indians/Alaska
Natives (AIAN) are relevant to currently manufactured
chrysotile asbestos in this Draft RE for Asbestos.
Recommendation 84: AIAN DODulations should be
included in the PESS discussion and analysis.
PUBLIC COMMENTS:
• Tribal communities need to be given consideration as
susceptible population because of dependence on
potentially contaminated foods, higher prevalence of
cigarette smoking, close proximity to landfill or waste
disposal site, higher mortality rate of lung cancer than
non-Hispanic Whites.
EPA did not identify reasonably available information to
indicates that the AIAN population is a potentially exposed
or susceptible population. EPA acknowledges that there are
unique health statistics for the AIAN population, but EPA
did not identify evidence indicating that there is greater
susceptibility for this population than other populations.
7.6 Family members and others in communities exposed through occupational take-home exposures
SACC,
41,58,
73, 85
SACC COMMENTS:
• The longer latency period for children as DIY
bystanders is discussed in the Draft RE for Asbestos but
The chrysotile asbestos IUR in Part 1 of the Risk Evaluation
for Asbestos incorporates mesothelioma risk, which is a
function of time since first exposure, so higher risks for
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this is not incorporated into the exposure or risk
modeling. Take home routes of exposure are not
discussed in the Draft RE for Asbestos, and this is a
primary route of exposures to which family members of
workers are exposed to asbestos; in particular, children
are highly susceptible.
PUBLIC COMMENTS:
• There's evidence showing that asbestos-related disease
is linked to take-home or para-occupational exposure.
Therefore, workers' household is a subpopulation under
risk of exposure to asbestos.
children are incorporated in risk calculations for particular
COUs.
Take-home exposures are possible for most of COUs
including auto brake and gaskets. However, the frequency
and magnitude of take-home exposure and contaminations
on clothing and shoes depend on several potential factors,
including personal hygiene and visibility of the chemical on
skin or clothing. EPA acknowledges that take-home
exposures may occur and that take-home exposures have
been shown to cause health effects among non-workers
exposed to take-home asbestos exposures, however, EPA
does not believe there are reasonably available data to
reliably predict take-home exposure and any associated risks.
7.7 Consider workers with unique conditions
73
PUBLIC COMMENTS:
• Vulnerable workers who are unauthorized immigrants,
low-income persons, homeless, the ex-incarcerated, and
do not speak English are unique category of "potentially
susceptible or exposed subpopulations." They are often
less familiar with asbestos-containing materials, are less
likely to make inquiries about proper work practices,
training, and equipment, are significantly less likely to
complain about unsafe working conditions, therefore in
need of consideration.
EPA thanks the commenter for these suggestions and
acknowledges that these subpopulations may have the
potential to be at a disadvantage when it comes to
communications related to or protections from
environmental policies and regulations. For Part 1 of the
Risk Evaluation for Asbestos and the risk determinations, the
process relies upon evaluation of COUs and the relevant
populations that are expected or anticipated to be exposed.
7.8 Additional populations to consider
SACC,
43
SACC COMMENTS:
• Recommendation 86: Discuss the possibility that
asbestos-containing construction materials still in
EPA identified and evaluated all reasonably available
information to determine PESS relevant for chrysotile
asbestos exposures from COUs included in Part 1 of the Risk
Evaluation. EPA makes conclusions on PESS based on
evidence and reasonably available information and does not
rely on speculation or hypotheses for identification PESS for
risk determinations. ACBM and those potentially exposed
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commerce identify certain construction workers as a
PESS.
PUBLIC COMMENTS:
• The exposed population to brake pad dust is not only
those who drive, but also potentially those that live and
work downwind, or nearby, the roadways.
will be further considered in Part 2 of the Risk Evaluation
(legacy uses and other fiber types of asbestos).
7.9 Subpopulations not defined appropriately
42
PUBLIC COMMENTS:
• It is mere speculation that genetic predisposition for
mesothelioma caused by germline mutation in BAP1
makes any specific person more genetically susceptible
to mesothelioma than someone else.
• The definition of "susceptible subpopulations" is not
warranted because the populations included have a low
probability of exposure to asbestos through working
with brakes or gaskets.
• Since concerns about sensitive subpopulations have
focused on exposure scenarios where millions of
citizens are exposed to appreciable levels of a toxicant,
the sensitive subpopulations defined in this report were
not appropriate because they are only composed of a
handful of adults across the nation who might be
exposed to the scenarios presented.
With regard to BAP1, EPA states in Section 3.2.4 that there
is "some evidence of genetic predisposition for
mesothelioma related to having a germline mutation in
BAP1." EPA cited Testa et al. (2011) as iust one example of
a study reporting an association between BAP1 mutations
and mesothelioma incidence, and EPA believes its inclusion
is warranted.
EPA continues to believe the PESS described in Part 1 of the
Risk Evaluation are accurate and warrant inclusion.
7.10 Extent to which the uncertainty around PESS been adequately characterized
SACC
SACC COMMENTS:
• The SACC concluded that the uncertainty around PESS
has been adequately characterized. In several sections
(i.e., Sections 2.3.1.3.6, 2.3.1.4.6, 2.3.1.5.6, 2.3.1.6.6,
2.3.1.7.6, 2.3.1.9.5), data assumptions, uncertainties,
and level of confidence are discussed. Although the
uncertainty analysis does not quantify uncertainty, a
sensitivity analysis was performed (Section 4.3.7 and
EPA appreciates these comments from the SACC. EPA has
not included upper and lower bounds to describe the
uncertainty in the exposure estimates, as the approach that
has been used in the TSC A REs has instead presented the
central tendency and high end estimates with confidence
ratings in addition to sections on key assumptions,
uncertainties, and confidence for exposures related to each
cou.
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Appendix L), which helps provide insights to how
uncertainties impact risks for DIY users and bystanders
for the brake repair/replacement scenarios. These same
insights apply to PESS.
• Estimates for chrysotile asbestos exposures for the
COUs evaluated are highly uncertain. Given this
situation, EPA has purposely chosen exposure estimates
that were likely high, within the respective error bands
in keeping with the precautionary principle of defaulting
to reasonable worst case in the face of uncertainty. EPA
has concluded, for example, that the risk of exposure to
chrysotile asbestos from brake shoe repair was
unacceptable. In the opinion of the SACC, EPA has
acted appropriately in the face of this uncertainty.
Specifically, EPA appropriately traded conservatism for
high quality data. However, EPA should attempt to
describe the uncertainty in the resulting estimates by
providing both upper and lower bounds that are
consistent with the limitations of the data available.
7.11 Risk to DIYs and ONUs who would not be expected to use PPE (Draft RE for Asbestos Sections 4.2.1 and 4.3.7)
SACC,
43, 85
SACC COMMENTS:
• The assumptions, data gaps, limitations, and rationale
for the risk characterization for ONUs were clear and
easy to follow. SACC considered it appropriate for EPA
to not assume PPE use for ONUs. Section 4.2.1 clearly
explains the approach for estimating risk from asbestos
exposure for workers and non-workers. Section 4.3.7
explains the confidence in estimates for workers and
ONUs.
• The estimates on the number of ONUs for most COUs
are low, except for the chlor-alkali plant workers. There
are few chlor-alkali plants and tasks that are clearly
described and numbers of workers by tasks tabulated.
EPA agrees that there are challenges associated with use of
PPE; they are described in Section 5.1. By providing risk
estimates that account for use of PPE, EPA is not
recommending or requiring use of PPE. Rather, these risk
estimates are part of EPA's approach for developing
exposure assessments for workers that relies on the
reasonably available information and expert judgment. When
appropriate, EPA will develop exposure scenarios both with
and without engineering controls and/or PPE that may be
applicable to particular worker tasks on a case-specific basis
for a given chemical. EPA did assess the risk to workers and
ONUs in the absence of PPE, and those risks are presented in
Section 4 Risk Characterization under Table 4-55, Summary
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Table 4-54 would be improved if a column were added
for an assessment of the confidence in the estimates and
a short description of how the values were obtained.
• Recommendation 89: Incorporate results from the
NIOSH/BLS survey of respirator use across industry
groups into the discussion of respirator use by ONUs.
PUBLIC COMMENTS:
• The DIY television shows which teach homeowners
about handling materials without always wearing proper
protective suits can mislead the public and create more
exposure for homeowners and families.
• EPA lacks data measuring exposures by workers who
do not regularly handle or work with asbestos but who
work in or near areas where asbestos is used including
the cleaning workers, skilled trade workers, supervisors,
and managers who EPA misleadingly characterizes as
ONUs. The range of workers that EPA defines as ONUs
is too large to support a single classification.
Supervisors have very different exposure patterns than
skilled trade workers, yet EPA assumes both groups of
workers face similar risks under EPA's overbroad ONU
categorization.
of Risk Estimates for Inhalation Exposures to Workers and
ONUs by COU.
While EPA has evaluated worker risk with and without PPE,
as a matter of policy, EPA does not believe it should assume
that workers are unprotected by PPE where such PPE might
be necessary to meet federal regulations, unless it has
evidence that workers are unprotected. For the purposes of
determining whether or not a COU presents unreasonable
risks, EPA incorporates assumptions regarding PPE use
based on information and judgement underlying the exposure
scenarios. These assumptions are described in the
unreasonable risk determination for each COU, in Section
5.2. Additionally, in consideration of the uncertainties and
variabilities in PPE usage, including the duration of PPE
usage, EPA uses the high-end exposure value when making
its unreasonable risk determination in order to address those
uncertainties. EPA has also outlined its PPE assumptions in
Section 5.1.
8. Overall Content and Organization
Charge Question 7:
7.1 Please comment on the overall content, organization, and presentation of the asbestos draft risk evaluation. Please provide
suggestions for improving the clarity of the information presented.
7.2 Please comment on the objectivity of the information used to support the risk characterization and the sensitivity of the agency's
conclusions to analytic decisions made.
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8.1 Draft RE for Asbestos is clear, thorough, and transparent
SACC,
40, 42,
79
SACC COMMENTS:
• Overall organization and presentation of the material in
the Draft RE for Asbestos is clear and well organized.
• The approach used in the Draft RE for Asbestos to
assess occupational exposures is adequately explained
and the arguments presented could be followed. There is
substantial discussion devoted to the scope of the Draft
RE for Asbestos.
• The various assumptions regarding exposures based on
monitoring data and other assumptions, such as the use
of PPE, were reasonably comprehensive.
PUBLIC COMMENTS:
• EPA's Draft RE for Asbestos represents an enormous
effort on the part of EPA. It is a very detailed and
transparent EPA analysis and focused on the objectives.
EPA was very thorough in making the uncertainties of
the assessment transparent.
• EPA is to be commended on such a substantial effort to
compile and review numerous studies and evaluate
exposures and risks of chrysotile.
• Commenter applauded EPA staff for the care and
patience that they expended into the analysis.
EPA thanks the SACC and public commenters for these
acknowledgements of effort and technical proficiency.
8.2 Draft RE for Asbestos title is misleading
SACC
SACC COMMENTS:
• The title is misleading in that the evaluation discusses
the risks from commercial use of only the chrysotile
form of asbestos and not asbestos in general as implied
in the title. Make the title specific to chrysotile asbestos
EPA agrees with the SACC and has changed the name of to
Risk Evaluation for Asbestos Part 1: Chrysotile Asbestos.
The Risk Evaluation for Asbestos Part 2 will include Legacy
Uses and Other Fiber types of Asbestos.
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and be specific in the Draft RE for Asbestos when data
from other fiber types are used.
• Recommendation 15: Either retitle the evaluation to
reflect its limited scope or postpone completion pending
future efforts to assess asbestos more broadly.
8,3 Clarify regulatory charge, scope, and rationale of evaluation
SACC,
42, 64,
95
SACC COMMENTS:
• Recommendation 5: Reduce technically intense text.
• As discussed in response to Question 2.1, the SACC
found that the Draft RE for Asbestos does not
adequately outline its purpose, which seems to be to
evaluate the risk of present commercial use of chrysotile
asbestos. In addition, it is unclear what the specific
regulatory objectives of the Draft RE for Asbestos
include.
• Recommendation 90: Provide more discussion in the
introduction on the regulatory charge and scope to help
establish the focus of the evaluation.
• Recommendation 17: How this limited scope Draft RE
for Asbestos for chrysotile asbestos fits into the larger
asbestos evaluation process should be explained early in
the document.
• Recommendation 63: Provide ciualifvins statements as
to the limitations of the Draft RE for Asbestos and its
analyses in its restriction to current intentional uses of
chrysotile asbestos fibers and only including lung
cancer and mesothelioma mortality.
PUBLIC COMMENTS:
• Reviewing TSCA, commenters were unable to find a
rationale justifying the preparation of the document.
One commenter was not convinced that EPA is required
EPA understands the need for additional clarity on the efforts
and process to complete the risk evaluation for asbestos.
EPA has added a Preamble to Part 1 of the Risk Evaluation
of Asbestos to clarify that the current document is focused
on imported, processed, and distributed uses of chrysotile
asbestos. Part 2 of the Risk Evaluation for Asbestos, as
described in the Preamble, will begin with a draft scope
document that is being developed to articulate EPA's plan to
evaluate other uses and disposals of asbestos and other fiber
types. This scope document will be available for public
comment.
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to address this topic to fulfill its responsibilities under
the Lautenberg Act.
• It is not clear why EPA used the following approach: In
the problem formulation document, it was stated that the
Draft RE for Asbestos would focus on epidemiological
inhalation data on lung cancer and mesothelioma for all
TSCA Title II fiber types, just as stated in the 1988 EPA
IRIS Assessment on Asbestos (U.S. EPA (1988b). This
rationale needs to be explained in more detail.
• EPA should refocus on the information needs for risk
management decisions by asking whether the
assessment is achieving its objective to inform
decisions. For this Draft RE for Asbestos, the answer is
'no.' The risk assessment team needs to "make
adjustments, revisit steps or develop additional
information as needed."
X
H
oc
jand discussion of mode of action (MOA)
SACC
SACC COMMENTS:
• The EPA Cancer Guidelines (U.S. EPA (2005)
specifies that the choice of risk estimation
methodology be based on the MOA by which a
substance causes cancer. The discussion in the Draft
RE for Asbestos of the MOA for asbestos should be
expanded.
• Recommendation 94: Revise the MOA discussion in
Section 3 to incorporate effects of dimensionality,
physical-chemical properties and bio-persistence,
which may affect and influence adverse outcome
pathways. Some discussion of the MOA should be
presented in more detail, specifically describing how
those processes may affect and influence the available
toxicity data for long-lived aquatic receptors.
Following SACC recommendations, EPA sufficiently
expanded the MOA discussion (Section 3.2.2.3) providing
more details.
EPA has not expanded the MOA discussion to address long-
lived aquatic receptors because releases to water are not
known or reported for the COUs evaluated in this Risk
Evaluation for Asbestos Part 1, and therefore, water
pathways are not expected to result in unreasonable risk.
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8.5 Su
jplemental documents should include updated photos of asbestos-containing building materials
15, 17,
29, 30
PUBLIC COMMENTS:
• EPA needs to set aside more time to study, formulate,
and publish "subsequent supplemental documents"
about ACBMs. These supplemental documents should
be complete and easy to read, to interpret, and to put
into practice. The supplemental documents should avoid
old photographs but use most current digital
photographs of Legacy ACBMs for building owners and
residents to use to identify ACBMs in buildings.
EPA thanks the commenter for these suggestions and will
take this into consideration when developing the Part 2 of the
Risk Evaluation for Asbestos, beginning with a scope
document that will describe COUs to be included.
8.6 Include CAS registry numbers
SACC,
28
SACC COMMENTS:
• Recommendation 41: Append CAS Registry Numbers
when referring to asbestiform varieties.
PUBLIC COMMENTS:
• The EPA did a good job in acknowledging the Chemical
Abstract Service Registry Numbers (CASRNs) "are
available for specific fiber types," other than the general
CASRN for "asbestos," but the EPA should specifically
identify the applicable CASRNs for each of the
regulated fiber types noted in the document to avoid
confusion with the non-asbestiform analogs.
EPA provided the CASRNs for each of the fiber types
included in the risk evaluation in Table 2-1 of the Scope
Document. EPA adopted the TSCA Title IIAHERA
definition of asbestos which does not include non-
asbestiform analogs. EPA has added a Preamble to clarify
the focus of Part 1 and Part 2 of the Risk Evaluation for
Asbestos.
8,7 Tables should be condensed and modified for readability
SACC
SACC COMMENTS:
• The tables in the document are not easy to read with
only a few entries and the large quantities of them. A
EPA appreciates these suggestions to improve the readability
of Part 1 of the Risk Evaluation for Asbestos. EPA will take
these suggestions into account when developing subsequent
risk evaluations.
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graphical presentation can be considered as an adjunct
to the summary table.
• Recommendation 64: Summarize Table 4.2 to Table
4.38 in one table and showing results relative to the
cancer benchmark value.
• Recommendation 65: Consider summarizing risks to
works and ONUs across scenarios in a graph.
• Readability would be improved if tables could be
modified to each use; specifically, color codes could be
used to highlight particularly relevant data.
• Table 2-1 could use a footnote describing the
abbreviations for the benefit of readers not familiar with
the environmental quality shorthand.
8.8 Clarify derivation of IURllt
SACC
SACC COMMENTS:
• For the calculation of cancer risk for workers and
consumers, EPA uses less than a lifetime inhalation unit
risk (IURi.i.t). Its derivation and methodology used are
not clear. Recommendation 70: Present clearlv how the
values for less than lifetime inhalation unit risk
(IURi.i.t) are calculated in the text.
The methodology for the derivation of the values is
described in Appendix K. It generally follows derivation of
IUR sections, that are cited in Appendix K.
8,9 Other recommendations to improve document clarity, particularly regarding uncertainties
SACC
SACC COMMENTS:
• Recommendation 74: Provide a tabular summary of the
uncertainties and carry some of the uncertainties
through to provide risk estimates in sensitivity analyses
by making alternate assumptions.
• In prior DREs, EPA defaulted to central tendency
worker exposure point air concentrations as a surrogate
for ONU exposure point air concentrations. The reason
EPA will consider providing a tabular summary of
uncertainties in future risk evaluations but was not able to
generate such tables in the timeframe for the current
document. However, EPA did note uncertainties, where
appropriate, and sensitivity analyses, when conducted.
In Part 1 of the Risk Evaluation, EPA did not need to default
to central tendency work exposure point air concentrations as
a surrogate for ONU exposures because, Section 2.3.1 states,
"where available, EPA used inhalation monitoring data from
industry, trade associations, or the public literature.. .For
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for deviating from this approach in this Draft RE for
Asbestos is not adequately explained.
• Table 2.24 (p. 106) is well presented, but the confidence
ratings are not necessarily adequately justified.
Specifically, exposure estimates are primarily derived
from simulations which might not represent real-world
conditions; the uniform medium confidence ratings are
poorly justified. COU estimates assigned low
confidence ratings were not controversial, given they
represent scenarios with very little available information
or where the quality of the data is questionable.
inhalation exposure, in cases where no ONU sampling data
are available, EPA typically assumes that ONU inhalation
exposure is comparable to area monitoring results that may
be available or assumes that ONU exposure is likely lower
than workers."
All but one air concentration estimate in table 2-24 are based
on actual monitoring data. The only estimate based on a
"simulation" is ONU exposure for gasket stamping COU.
The confidence ratings relate to how closely these values
represent the actual concentration of the workplaces. The
factors and considerations contributed to each confidence
rating are detailed in the Data Assumptions, Uncertainties,
and Level of Confidence section in each COU. The factor
and considerations include relevance, representativeness, and
age of the data.
8.10 Map and correlate asbestos deposits in natural environment
SACC
SACC COMMENTS:
• Since asbestos is a naturally occurring mineral, the
Draft RE for Asbestos should include a map showing
the locations of naturally occurring asbestos deposits
such as provided by USGS on its website.
• To better understand the potential impact of these
natural deposits, it would be appropriate to determine if
there is a correlation between the location of asbestos
deposits and the prevalence (and concentrations) of
drinking water or air measurement detects.
EPA acknowledges that this addition to the document would
have added useful context and background, however, this
information was not added due to time constraints and it was
not necessary for the evaluation and determination of risk for
COUs evaluated in Part 1 of the Risk Evaluation for
Asbestos.
8,11 Define terms
SACC
SACC COMMENTS:
• On page 56 (In. 1951), the term "friable" is used
without definition. One member suggests defining the
term where first used.
EPA has added a definition for the term "friable."
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8.12 Correct the attribution for statements about asbestos being vital
SACC
SACC COMMENTS:
• On page 60 (In. 2109), the Draft RE for Asbestos
describes that asbestos filters as being "vital" to the
continued success of the chlor-alkali industry. However,
such position should be attributed to industry and not to
USGS.
EPA has revised this sentence to more accurately attribute
physiochemical properties to USGS and not viewpoint that
asbestos filters are "vital."
8.13 Correct quotation/citation
42
PUBLIC COMMENTS:
• Regarding Richter et al. (2009) cited in the Draft RE for
Asbestos, the quote needs to be corrected. On page 88,
lines 3169-3171, the Draft RE for Asbestos says:
"Since the mid-1990s, material and design ... phasing
out drum brakes in passenger automobiles (Richter et al.
(2009)." However, on case 459 of the oaoer, the full
quote is, "The introduction of disc brakes in the 1960s
in the United States ... By the 1990s, most automobiles
sold in the United States had disc brakes on all four
wheels." (42-210)
• On page 88, lines 3180-3182, Draft RE for Asbestos
says: "Use of asbestos-containing braking systems
began to decline in the 1970s ... and availability of
asbestos-free substitutes (Paustenbach et al. (2004a)."
This is appropriately quoted but could add that litigation
associated with asbestos that has occurred since 1975
ensured that no asbestos-containing auto parts would be
present in cars in the post-1980 or 1985 era.
EPA has revised the text to improve accuracy. EPA did not
elaborate on litigation.
8.14 Clarification on Jiang et al. (2008) - obtaining clutches or brakes with asbestos is not likely in 2020
42
PUBLIC COMMENTS:
• It is incorrect to suggest that it is plausible in 2020 to
obtain clutches or brakes that contain asbestos from a
warehouse. As noted in the article Jiang et al. (2008),
the authors believe the bulk of exposures when handling
While the authors make this assertion, EPA must take into
consideration that there is the potential to obtain asbestos-
containing brakes, which was supported by the SACC.
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boxes of old brakes or clutches was due to dust not on
the inside but on the outside of the box which contained
asbestos from near the production.
8,15 Revise how Paustenbach et al. (2006) is interpreted
42
PUBLIC COMMENTS:
• Commenter suggested that EPA embrace this sentence:
"Overall, based on the PCM analysis of the 23 valid
samples, the study authors reported an average worker
asbestos concentration of 0.024 fibers/cc and a
maximum concentration of 0.066 fibers/cc (Paustenbach
et al. (2006)." Commenter was involved in the testing of
the samples, 17 out of 23 had no detectable
concentrations of asbestos (by PCM). It is unlikely that
the six samples that had detectable asbestos
concentrations were overloaded with chrysotile asbestos
fibers from an encapsulated gasket.
EPA states in Section 2.3.1.9.4 that 17 of 23 samples were
non-detect and that 6 samples contained asbestos as detected
using TEM. Furthermore, in Section 2.3.1.9.4, EPA clarifies
the uncertainties in the Paustenbach study related to five of
the personal breathing zone samples being overloaded by
particulates, and thus, not being suitable for analysis. EPA
does not assert that these samples are overloaded with
chrysotile but does acknowledge that they "cannot rule out
the possibility that these overloaded filters might have
contained elevated levels of asbestos," in Section 2.3.1.9.
8,16 Remove the term "inert"
SACC
SACC COMMENTS:
• Recommendation 10: Remove the text describing
chrysotile asbestos as "biologically inert." Many micro-
and nano-sized materials have been shown to have
significant biological effects following absorption even
though they may be "chemically inert," especially
importance of size/length characterization.
EPA has revised the risk evaluation draft document to avoid
describing chrysotile as biologically inert (e.g, the text
biologically was removed from the second sentence in
Section 2.1.
8.17 Use the term "chrysotile asbestos" in place of the single word "chrysotile"
SACC
SACC COMMENTS:
• There is a constant shifting, in the Draft RE for
Asbestos and especially in Section 3.2.4, in use of the
words "asbestos" and "chrysotile." This is not only
confusing but also misrepresentative of the actual data.
The Draft RE for Asbestos is restricted in scope to
chrysotile asbestos only and is not about asbestos. The
EPA agrees with the SACC that this would add clarity. In
many instances, EPA followed SACC recommendation and
used "chrysotile asbestos" instead of just chrysotile
throughout the text of the risk evaluation (except where
direct quotes are using word chrysotile). However, a footnote
was also added in the Preamble to the document that
chrysotile refers to chrysotile asbestos.
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correct term should be "chrysotile asbestos," and this
should be clear throughout the entire document.
• Recommendation 39: Use the term "chrvsotile asbestos"
in place of the single word "chrysotile" and in any
references to "asbestos" data or estimates that
specifically reference chrysotile asbestos.
8.18 Clarify terms for asbestiform and non-asbestiform varieties
SACC,
28, 75
SACC COMMENTS:
• Several varieties of amphiboles are present in both
asbestiform and non-asbestiform habits: tremolite,
anthophyllite and actinolite. Whenever the asbestiform
varieties of these substances are referenced, "asbestos"
should be attached to their name. Recommendation 40:
Append the word "asbestos" to all references to
amphiboles.
PUBLIC COMMENTS:
• EPA should add the word "asbestos" following use of
the words "anthophyllite," "tremolite" and "actinolite."
The inclusions would avoid unintended confusion with
their non-asbestiform analogs. Similarly, EPA should
add the word "asbestiform" before the words
"serpentine," "riebeckite" and "cummingtonite-
grunerite." The word "asbestiform" is a description of
mineral morphology as opposed to "asbestos."
For the purposes of the asbestos risk evaluation, EPA
adopted the TSCA Title II definition of asbestos which is the
"asbestiform varieties of six fiber types - chrysotile
(serpentine), crocidolite (riebeckite), amosite
(cummingtonite-grunerite), anthophyllite, tremolite or
actinolite." As such, EPA is only evaluating the asbestiform
varieties of these mineral fibers. EPA added a preamble to
the chrysotile risk evaluation document that further explains
the asbestos fibers being evaluated in Part 1 and Part 2 of the
asbestos risk evaluation. In Part 1 of the Risk Evaluation for
Asbestos, EPA has further clarified that non-asbestiform
mineral varieties are not included in the added Preamble.
8.19 Use more complete descriptions of "risk" wording
SACC
SACC COMMENTS:
• There are cases in the Draft RE for Asbestos where the
wording suggests that risk below 1x10-4 or 1x10-6 are
the same as "no risk." To avoid misinterpretation of the
Draft RE for Asbestos findings by the public at large by
recommending that statements using the phrases "no
risk" or "risk still persisted" should be revised to be
clearer. An example would be to report that "risks are
EPA has clarified the text in Part 1 of the Risk Evaluation for
Asbestos used to describe risk.
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estimated to be below target risks" or "risks are
estimated to be above the target risks."
8.20 Include data gaps section
SACC
SACC COMMENTS:
• Recommendation 72: Include a section that identifies
data gaps; information that is needed to improve
estimates of populations at risk.
EPA requested information on all aspects of risk evaluations
throughout the risk evaluation process, including opening
public dockets for receipt of such information, conducting
outreach to manufacturers, processors, users and other
stakeholders, as well as conducting tailored data
development efforts for some of the first 10 chemicals.
Given the timeframe for conducting risk evaluations on the
first 10 chemicals, use of TSCA data gathering authorities
has been limited in scope. In general, EPA intends to utilize
TSCA data gathering authorities more routinely for the next
20 risk evaluations.
EPA has identified in several sections the key assumptions
necessary to fill and uncertainties associated with data gaps
to complete the risk evaluations utilizing the data identified
and evaluated as part of EPA's systematic review process. In
addition, EPA performed additional supplemental, targeted
searches to fill data gaps where feasible.
8.21 Be clearer on how cited epidemiology papers conducted and modeled their studies
SACC
SACC COMMENTS:
• SACC made editorial comments made regarding the
Draft RE for Asbestos. These comments include
discrepancies noted in the document about the Berman
and Crump (2008a) paper, the Loomis et al. (2009)
oaoer, and the Elliott et al. (2012) studv. Overall, the
SACC suggests that EPA be clearer in how the papers
used to identify exposure and risk conducted and
modeled each of their epidemiological studies, and that
statistical analyses that were used. The SACC listed out
the references in correlation to the line number(s) of the
EPA made multiple edits according to editorial comments
provided by the panel, including descriptions of Berman and
Crump (2008a), Elliott et al. (2012) and Loomis et al. (2009)
and a number of other responsive changes.
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Draft RE for Asbestos document being addressed and
outline specific places in the document where edits are
recommended.
8.22 Rename the section "selected optical properties"
28
PUBLIC COMMENTS:
• EPA needs to be consistent with the referenced NIOSH
Current intelligence bulletin 62: Asbestos fibers and
other elongate mineral particles: State of the science
and roadmap for research. In outlining the optical
properties of asbestiform, EPA should rename the
section "Selected optical properties" since it is not a
complete listing of optical properties useful for the
identification of the various asbestos minerals (i.e.,
refractive index is not included).
EPA has revised Table 1-1 to include only the most relevant
properties. Optical properties are no longer presented.
8.23 Redefine the term "most susceptible"
42
PUBLIC COMMENTS:
• The term "most susceptible" used in the following
sentence is misleading: "Workers exposed to asbestos in
workplace air, especially if they work directly with
asbestos, are most susceptible to the health effects
associated with asbestos." (p.23, In. 972 - 973) The
word susceptibly was and should be limited to those
who are biologically more susceptible like children and
elderly. Relatively high exposure and susceptibility
should not be confused as similar terms as they are
entirely different concepts.
EPA has revised this sentence to clarify that the assertion
that these workers are most susceptible is due to higher
exposures. While EPA acknowledges there are a wide
variety of perspectives and definitions related to
susceptibility, the risk evaluations consider susceptibility
related to both physiologic factors and exposures.
8.24 EPA ignored gaps identified in the Problem Formulation
SACC,
97
SACC COMMENTS:
• EPA ignored the gaps identified in the Problem
Formulation and did not mandate collection of
monitoring data, specifically on the efficacy of asbestos
removal by filtration in the chlor-alkali process. There's
With regard to the chlor-alkali process, EPA conducted site
visits to 2 chlor-alkali facilities as described in the Scope and
PF document and also held conference calls with industry
regarding processing and disposal of asbestos diaphragms.
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a large uncertainty for environmental exposures due to a
general lack of monitoring data present for surface
water. Recommendation 95: Harmonize differences
between issues raised in the Problem Formulation
document and those evaluated in the Draft RE for
Asbestos.
PUBLIC COMMENTS:
• Based on the many information gaps in the problem
formulation, commenters petitioned EPA to use its
authority under TSCA to require industry to report
comprehensive import, use, and exposure information to
inform the risk evaluation; however, EPA did not do so.
EPA did not use its TSCA data collection authorities to
gather additional information regarding asbestos because
EPA believes it had sufficient information to complete Part 1
of the Risk Evaluation for Asbestos using a weight of
scientific evidence approach. EPA selected the first 10
chemicals for risk evaluation based in part on its assessment
that these chemicals could be assessed without the need for
regulatory information collection or development. When
preparing this risk evaluation, EPA obtained and considered
reasonably available information, defined as information that
EPA possesses, or can reasonably obtain and synthesize for
use in risk evaluations, considering the deadlines for
completing the evaluation.
8.25 The Draft RE for Asbestos is not "fit for purpose"
64
PUBLIC COMMENTS:
• With respect to risk management decisions pertaining to
exposures to dusts generated in motor vehicle repair, the
Draft RE for Asbestos is not 'fit for purpose.' This Draft
RE for Asbestos estimates risks for exposures to
chrysotile fibers as previously found in asbestos textile
manufacturing, which no longer exist in the US. The
Draft RE for Asbestos does not make a valid assessment
of risks associated with compact particles of heat-
modified chrysotile as were formerly found in motor
vehicle repair environments.
• The Draft RE for Asbestos is not fit for the purpose of
informing risk management decisions pertaining to
chrysotile in motor vehicle repair environments. It
ignores the large body of epidemiologic studies, in vivo
laboratory animal studies, in vitro studies, and
mechanistic, kinetic, and mode of action (toxicity
pathways) studies that contribute to hazard
identification for compact particles, such as heat-
EPA has evaluated risk from exposure to chrysotile asbestos
in Part 1 based on the relevant COUs that were described in
the Scope document and Problem Formulation document.
Part 2 of the Risk Evaluation for Asbestos will evaluate risks
related to COUs for legacy uses and associated disposals for
asbestos and will include other fiber types. Part land Part 2
will comprise EPA's Risk Evaluation for Asbestos, and EPA
is confident that its evaluation is "fit for purpose" in the
context of meeting the statutory requirements under TSCA.
EPA considered all relevant information that was reasonably
available. Part 1 of the Risk Evaluation for Asbestos includes
narrative describing the process used to select studies for
which data was utilized for the evaluation. Additional
inclusion/exclusion criteria for all studies is included the
Application of Systematic Review in TSCA Risk
Evaluations document. Furthermore, EPA made available the
documentation of the literature search strategy and the
resulting references with the Scone document and the data
quality evaluation and extraction files are provided as
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modified chrysotile as found in motor vehicle repair
environments.
Supplemental Files to Part 1 of the Risk Evaluation for
Asbestos.
8,26 The Draft RE for Asbestos does not address TSCA requirements
68
PUBLIC COMMENTS:
• The provided risk assessment exercise does not address
the task as defined by TSCA. EPA does not actually
address "asbestos" in this risk assessment.
Part 1 of the Risk Evaluation for Asbestos is focused on risk
determinations for exposures to uses of chrysotile asbestos.
EPA is developing a supplemental scope document to look at
legacy uses and associated disposals for asbestos, which will
inherently consider other fiber types included in the
definition for asbestos adopted by EPA for the purposes of
the asbestos risk evaluation under TSCA. The definition and
plan for the asbestos risk evaluation is clarified in the
Preamble.
8.27 Correct error in Table 2-4
42
PUBLIC COMMENTS:
• It is not clear why Table 2-4 has 11 f/cc as the
maximum result when, as noted in the footnote, it
should read 0.019 fibers/cc. This incongruency is
perhaps just a typographical error that needs to be
corrected.
EPA clarifies that 11 f/cc is the maximum value reported in
the study despite it being considered an anomaly. For
accuracy, this maximum value is reported with the next
highest value being indicated in a footnote for appropriate
interpretati on/consi derati on.
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8,28 Non-cancer effects of chrysotile are not similar to Libby amphibole
82
PUBLIC COMMENTS:
• In the Draft RE for Asbestos, the sentence "if the non-
cancer effects (e.g, asbestosis and pleural thickening) of
chrysotile are similar to Libby amphibole asbestos, the
non-cancer effects of chrysotile are likely to contribute
to the overall health risk of asbestos beyond the risk of
cancer" (Draft RE for Asbestos In. 7636-7639) should
be deleted or modified as: (1) Libby amphibole is not
classified as one of the six asbestos types; (2) the
pleural thickening in individuals exposed to Libby
amphibole is remarkable and has not been noted in
chrysotile workers who exhibit asbestosis; and (3) there
are no scientific data supporting this hypothesis.
EPA believes there are inaccuracies in the comment as
asbestosis and pleural plaques are separate outcomes and are
evaluated independently. EPA did not find the suggested
revision to be warranted.
9. Systematic Review
EPA did not include a charge question specific to systematic review because, but SACC and public comments addressed these topics.
#
Summary of Comments for Specific Issues Related to
Systematic Review
EPA/OPPT Response
9.1 Systematic review supplemental file effort recognized
42
PUBLIC COMMENTS:
• The supporting document to the proposal, entitled
"DRAFT evaluation for Asbestos: Systematic Review
Supplemental file: Data Quality Evaluation of Human
Health Hazard Studies: Mesothelioma and Lung Cancer
Studies" (March 2020) shows extraordinary discipline
and patience of the staff.
EPA thanks the commenter for this acknowledgement.
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9.2 Relevant literature sources were overlooked or deemed inadequate
SACC,
95
SACC COMMENTS:
• Members reported finding relevant literature sources
that were apparently overlooked or deemed inadequate
(including occupational exposure).
• Recommendation 73: Use a broader set of exposure
assessment studies to estimate exposures for the
designated COUs.
PUBLIC COMMENTS:
• Commenter found nearly 100 relevant papers that were
not cited.
EPA clarified the literature search stratesv in the Scone for
the Risk Evaluation for the Asbestos and the related
supplemental files.
EPA appreciates the suggestions on the implementation of
systematic review under TSCA and is continuing to refine its
Systematic Review protocol. In addition, EPA is seeking
feedback from the National Academies of Science (NAS) on
its Systematic Review process, including data evaluation
criteria and data quality rating methods used in TSCA Risk
Evaluations. The NAS webinars took place from June
through August 2020. EPA will consider all comments and
feedback received in updating its protocol.
EPA will consider these comments during revisions to future
literature search strategy documents. The literature search for
the first 10 chemicals was conducted in consistency with
EPA's existing systematic review process.
9,3 Request to improve transparency, including use of previous assessments and process for backward searching
SACC,
34, 39,
42, 65,
77, 83,
87, 96,
106
SACC COMMENTS:
• Occupational and consumer exposures need further
discussion on the quality and relevance of available
exposure data. This is particularly an issue for the
gasket replacement COU.
• Recommendation 98: Clarifv qualitv and relevance of
occupational and consumer exposure data.
PUBLIC COMMENTS:
• For the systematic review, the scope of the literature
search appears to go beyond chrysotile asbestos,
suggesting that the IUR for chrysotile asbestos is
confounded by other forms. For greater transparency,
commenter asked for greater detail in how previous
assessments were leveraged for the current assessment
All studies used in Part 1 of the Risk Evaluation for
Asbestos, including industry submissions, are evaluated
using the same data quality criteria under the process
described in the Application of Systematic Review in TSCA
Risk Evaluations document. Specific information on data
quality evaluation are posted as Supplemental Files to Part 1
of the Risk Evaluation for Asbestos.
In consideration of comments received, EPA is in the
process of updating the TSCA Systematic Review protocol
to improve the transparency of this review process and
further reduce possible bias such that all studies are
appropriately considered.
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and what process was used to conduct the "back-ward"
searching.
• EPA distinguishes its systematic review of asbestos
from its previous draft risk evaluation but did not
explain the protocol by which it conducted the data
integration step to help in clarifying the differences in
approach.
• No clear definition of inclusion and exclusion criteria
for the identified and reviewed papers was provided
• EPA generally followed the Problem Formulation,
except that the systematic review does not seem
thorough, and there was an insufficient examination of
the quality of the critical assumptions regarding both the
exposure and cancer potency.
9.4 Comments about criteria for data/study inclusion and exclusion
SACC,
31,34,
39, 42,
60, 67,
77, 82,
83, 85,
87, 92,
95, 96,
105
SACC COMMENTS:
• The SACC generally supported EPA's hierarchy of
data>modeling> occupational exposure limits or
release limits, but some members suggested that data
collected in workplaces under normal operations should
have priority over data collected during work
simulations for litigation support.
• SACC noted several issues with the data quality
evaluation (DQE) and questioned why certain
references were not included in the Draft RE for
Asbestos while others were. For example, Celv-Garcia
et al. (2016b), estimated personal exposure to asbestos
of brake repair workers, was rated as 'High' in the
DQE, but did not appear to have been used in the Draft
RE for Asbestos. There were 29 studies in the DQE
with data extracted. Twenty-seven (27) of those studies
were in the data extraction file. It was not clear why or
how the list was narrowed from 27 studies down to just
EPA appreciates the comments and is currently in the
process of updating its Systematic Review protocol. In
addition, EPA awaiting feedback from the National
Academies of Science (NAS) on its Systematic Review
process, including data evaluation criteria and data quality
rating methods used in TSCA Risk Evaluations. The NAS
held webinars from June through August of 2020 to review
the TSCA's Systematic Review protocol. EPA will consider
all comments and feedback received in updating its Protocol.
Regarding the scope of Part 1 of the Risk Evaluation being
limited to lung cancer and mesothelioma, EPA described the
rationale for this in the Scope and Problem Formulation
documents. Briefly, these outcomes are those for which there
is high confidence in the association between exposure and
effect. However, in response to public comment and SACC
input, EPA has evaluated additional studies on laryngeal and
ovarian cancers to develop an adjustment factor to the IUR
to account for these other cancer in the risk estimates.
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the five studies cited in the Draft RE for Asbestos, with
data from only two of those studies actually used to
estimate exposures.
• Recommendation 30: Explain the inclusion/exclusion
criteria for brake and gasket exposure studies.
• Recommendation 31: Each study rated acceptable in
the DQE should be described/discussed and a
justification provided when results from that study are
not utilized in the risk evaluation.
PUBLIC COMMENTS:
• There is a lack of consideration of all data regarding
chrysotile asbestos. For the most part, only articles
favoring the conclusions of EPA are included in the
analyses.
• Was it appropriate to narrow the scope only to certain
cancers (lung and mesothelioma) in epidemiology
studies? Did EPA appropriately apply systematic
review principles when narrowing the scope? EPA's
systematic literature review as it relates to AABL is
overly narrow in scope and ignores a large body of
scientifically sound epidemiologic evidence that clearly
indicates no increased risk of asbestos-related disease
in persons working with and around AABL.
• EPA needs to re-consider these papers, Garabrant et al.
(2016; Goodman et al. (2004) regarded off-topic.
• EPA failed to include or exclude studies based on the
protocol's pre-specified criteria. EPA failed to use two
or more members of the review team to independently
screen and select studies.
• EPA has failed to appropriately document the
disposition of each of these 10,320 references
following title and abstract screening or offer an
explicit justification for their exclusion at the full text
screening step.
• In section 2.3.1.6, the single study considered by EPA
was rated "low" in the systematic review and the
EPA's quality evaluation method was developed following
identification and review of various published qualitative and
quantitative scoring systems to inform our own fit-for-
purpose tool. The development process involved reviewing
various evaluation tools/frameworks (e.g, OHAT Risk of
Bias tool, CRED, etc.; see Appendix A of the Application of
Systematic Review in TSCA Risk Evaluations document,
and references therein), as well as soliciting input from
scientists based on their expert knowledge about evaluating
various data/information sources specifically for risk
assessment purposes.
EPA published the Strategy for Conducting Literature
Searches for Asbestos in June 2017 along with the Scope
document for Asbestos, similar to all first 10 TSCA chemical
risk evaluations. This document outlined the literature search
strategy and title/abstract inclusion/exclusion criteria used
for screening, found in Appendix E.
Part 1 of the Risk Evaluation for Asbestos includes narrative
describing the process used to select studies for which data
was utilized for the evaluation (Section 1.5.1) Generally, for
consumer and bystander exposures, 30 studies were
identified, evaluated, and extracted. However, five studies
were selected for use based on the studies meeting certain
factors and assumptions described in Section 2.3.2.1 and
2.3.2.1.1 and the associated, assumed representativeness of
an expected DIY consumer scenario. Specifically, while they
were occupational in nature, the studies selected were studies
which did not involve the use of engineering controls, did
not involve PPE, did not involve methodologies
uncharacteristic of an expected consumer methodology.
Citations for each reference are provided, along with a link
to the HERO database to allow individuals to review at a
minimum, the abstract for each study identified to provide
some insight about each reference.
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limitations of this study are unacceptable. Such flimsy
data should not be used as "fit-for-purpose" or "best
available science."
• Draft RE for Asbestos fails to consider data collected
by accepted methods as required by TSC A as best
available science.
• EPA method for including studies in the literature flow
diagram for human health hazards is inconsistent with
its flow diagram for Environmental hazard in Figure 1-
7.
Inclusion/Exclusion criteria for all studies identified and
evaluated as part of EPA's systematic review process are
described in the Application of Systematic Review in TSCA
Risk Evaluations document published bv EPA.
A full description and discussion on each study rated
acceptable within Part 1 would result in prohibitively long
document with little added benefit in relation to justifications
when the process is described in the Application of
Systematic Review in TSCA Risk Evaluations document.
9.5 EPA should not rely on voluntary information from manufacturers/importers
77
PUBLIC COMMENTS:
• EPA should not rely on manufacturers/importers
voluntarily offering crucial exposure information.
All studies used in the Risk Evaluation, including industry
submissions, are evaluated using the same data quality
criteria under the TSCA Systematic Review process
described in the Application of Systematic Review in TSCA
Risk Evaluations document. In consideration of comments
received, EPA is in the process of updating the TSCA
Systematic Review protocol to improve the transparency of
this review process and further reduce possible bias such that
all studies are appropriately considered.
10. Physical/Chemical Properties
EPA did not include a charge question specific to physical and chemical properties, but SACC and public comments addressed this
topic.
#
Summary of Comments for Specific Issues Related to
Physical/Chemical Properties
EPA/OPPT Response
10.1 Conduct studies on physical/chemical properties
SACC,
109
SACC COMMENTS:
• Different testing methods such as surface area electron
diffraction (SAED) or energy dispersive X-ray analysis
(EDXA) versus phase contrast optical microscopy
(PCM) methods should be used to differentiate better
As part of the consideration of reasonably available
information and what is needed to conduct a risk evaluation,
EPA considers data gaps and the need for additional
information as appropriate. EPA considers reasonably
available data on a chemical by chemical basis and would
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between the morphological and structural
characterizations of types of fibers.
PUBLIC COMMENTS:
• Separate studies should be conducted on "the
characteristics," "homogeneous nature," or "friability of
each type of asbestos."
exercise information gathering in a fit-for-purpose manner.
EPA did not determine a need for more data on testing
methods or physical properties to conduct a risk evaluation
for asbestos.
10.2 Concerns about terminology and misclassification
SACC,
92
SACC COMMENTS:
• There's issue of the "purity" of the chrysotile used in
the products that are being evaluated by this review.
Since there is no evidence that any chrysotile asbestos
products have ever been amphibole asbestos free, the
SACC has concerns that all aftermarket brake
pads/linings may not be amphibole free.
• Some paragraphs are too technically written for the
general audience and are more appropriate for a
mineralogist.
PUBLIC COMMENTS:
• EPA's definition of asbestos used in the report is
outdated and does not consider the physical properties
of other fibers. This is based on 1980 rule of classifying
asbestiform versus non-asbestiform fibers, which thus
classified talcum products as non-asbestiform.
However, modern technologies do detect asbestiform
contamination in talcum powder, and the industry has
been linked with workers dying at higher rates of
mesothelioma and other cancers (Emorv et al. (2020).
• EPA should revisit the notion "no distinction between
fibers and cleavage fragments of comparable chemical
composition, size, and shape." As said in the National
Academy of Science's evaluation on NIOSH's Research
Roadmap on Asbestos, the definition of these
dimensions should be periodically refined as knowledge
The issue of purity and the possibilities of amphibole
contamination in commercial chrysotile fibers has already
been discussed in the Section 1.
EPA has revised and clarified the language used in Section
1.1.
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of these mineral particles and their potential for health
effects accumulates.
10.3 Improve discussion of fiber length and aerodynamic aspects
SACC,
82
SACC COMMENTS:
• The length of fibers was largely ignored in the risk
evaluation, given that this physical-chemical property
has significant impact on the biological responses of
asbestos.
• Recommendation 7: If available, provide metrics of
aerodynamics for each fiber type. At a minimum,
discussion regarding this characteristic should be
provided in the text.
• Recommendation 8: Discuss variation in fiber size and
length in addition to means, including the pros and cons
of different microscopy methods used to measure fibers.
• Recommendation 12: Include a discussion of properties
related to the suspension of fibers.
• Recommendation 81: Discuss the utilitv of fate models
derived from micro-fiber analyses for future ecological
assessments of asbestos.
PUBLIC COMMENTS:
• One of the most important physical properties
associated with asbestos fibers is the aerodynamic
aspects of the fiber that allow penetration into
pulmonary areas of the lung. This is not discussed in the
document.
EPA has included more information about the fiber length
and diameter in Section 1.1. The advantages and
disadvantages of different microscopy methods used to
measure fibers has been described.
EPA has added text in Section 3.2.2.3 to describe that
aerodynamic diameter is a determinant of deposition and
penetration of fibers into the respiratory tract.
10.4 Include information from animal studies on the physical-chemical properties
SACC
SACC COMMENTS:
• Recommendation 11: Include in the discussion of the
physical-chemical properties the fiber dimension and
surface changes of friction products known from animal
studies to be important to health outcomes.
EPA has added a new Section 3.2.2.3 on Mode of Action
Considerations for Asbestos which includes information on
the physiochemical properties of chrysotile fibers.
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10.5 FDA's parallel effort on chrysotile
SACC
SACC COMMENTS:
• Recommendation 13: Acknowledge that the U.S. Food
and Drug Administration (FDA) is conducting a
"parallel effort" to further explore the physical-chemical
properties and characteristics of chrysotile.
EPA is aware of the Interagency Working Group on
Asbestos in Consumer Products (IWGACP) effort to develop
standardized testing methods for asbestos and other mineral
particles of health concern in talc. EPA has several
representatives on the workgroup and is working with other
government scientists to develop recommendations on
asbestos testing and analytical methods.
10.6 NIOSH has background information
SACC
SACC COMMENTS:
• Recommendation 14: Note that NIOSH (2011) provides
helpful background information for readers of this DRE.
EPA has made revisions to present more chrysotile-specific
information on physical-chemical properties. EPA will
additionally consider NIOSH as a source of background
information in the Part 2 of the Risk Evaluation for Asbestos
where other uses of asbestos are evaluated.
11. Public Comment and Peer Review Processes
The following summarizes public comments addressing the public comment and peer review process.
#
Summary of Comments for Specific Issues Related to
Public Comment and Peer Review Processes
EPA/OPPT Response
11.1 Concerns about insufficient time
31,42,
51,66,
67, 88
PUBLIC COMMENTS:
• Less than 3 weeks (between April 3rd and 22nd) were
provided for comments to reach the SACC was largely
considered insufficient. Also, the timing of release for
this document during peak COVID limits the time many
physicians and scientists and other subject matter
experts to review this in a timely manner.
• If the report had been released before April, the 2-
month comment period may have been adequate,
considering the large scope of this report.
• Tribal environmental offices and staff being
disproportionately affected by the crisis, found the 60-
The Lautenberg amendments to TSCA provide a three- and
one-half-year timeframe for completion of existing chemical
risk evaluations. However, in the first year following
enactment, EPA's focus was on issuing the Risk Evaluation
Rule outlining the framework for implementing TSCA
section 6(b). Consequently, the time for completing the first
10 risk evaluations was compressed. As discussed in the
Introduction, EPA believed peer reviewers were most
effective in their role if they received the benefit of public
comments on draft risk evaluations prior to peer review. For
this reason, and consistent with standard Agency practice,
the public comment period preceded peer review. The final
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day comment period insufficient. In the future, a 90-day
comment period should be considered.
• The SACC would be most effective if they could
receive the public comments on Draft RE for Asbestos
prior to peer review. However, the time for the panelists
to digest the public before the meeting is too short.
risk evaluation changed in response to public comments
received on the draft risk evaluation and/or in response to
peer review, which itself may be informed by public
comments. EPA will consider these comments for future risk
evaluations. EPA acknowledges the coronavirus pandemic
and adapted accordingly, to include a virtual public meeting
for the SACC review. However, statutory requirements for
the timeline of the chemical risk evaluations under TSCA
were unchanged.
11.2 Balance, independence, and bias of peer review
42, 69,
74, 76,
80, 84,
89, 104
PUBLIC COMMENTS:
• It may be noted by trial lawyers, who will likely be
submitting comments, that all the meta-analyses were
conducted by experts who have testified on behalf of
defendants. That is true, but EPA should weigh the
quality of the work and the fact that they survived peer
review in journals with solid impact factors.
• NIOSH and OSHA did not evaluate or perform third
party assessments of exposure in the chlor-alkali
industry, instead relying on measurements from
employers. Validation should be required for the
respective data.
• The Draft RE for Asbestos should not be unduly
influenced by experts whose scientific theories have
been rejected as not representative of mainstream
science and whose involvement in asbestos advocacy
organizations calls into question the impartiality of their
work.
• Several commenters expressed that the EPA panel may
not be completely unbiased and without other financial
interest. One commenter stated that EPA appears to be
lobbied and guided by the Asbestos Disease Awareness
Organization - and affiliated individuals, some of
EPA has implemented procedures to obtain input by the
public and the SACC, and considers all comments submitted.
EPA has developed a rigorous process to identify all
reasonably available information and to evaluate scientific
data and information according to pre-defined criteria. The
assumptions and uncertainties related to analyses and
conclusions are noted throughout the risk evaluations.
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whom testify routinely as plaintiff experts in asbestos
cases, who are deeply committed to perpetuating the
narrative that brakes manufactured with chrysotile
asbestos pose a risk. EPA has placed three experts on
SACC, including ad hoc members, who earn significant
sums by testifying for plaintiffs in asbestos litigation
and, therefore, have a clear financial stake in the risk
evaluation's outcome. This participation is contrary to
EPA's own rules for conflicts of interest in connection
with participation on the SACC. Additionally, there are
calls for increased diversity in the EPA review panel.
• It may not be possible to form a committee of the top
experts in the field who have never been involved in
asbestos litigation in some way. However, "the
participation of experts involved in the litigation must
be balanced and provide EPA with a diversity of
perspectives."
• One comment recommended "expansion of the EPA
panel to include several leading epidemiologists,
toxicologists, mineralogists, biostatisticians, and
pathologists working worldwide"
• Although current panels contain many credible
professionals, only one or two persons on the panel/ad
hoc group have been seriously studying asbestos
toxicology and epidemiology for the recent decades.
Obtaining "an independent review of the science
underlying the risk assessment" is difficult.
• The Draft RE for Asbestos is the first comprehensive
assessment of asbestos risks in over 30 years. The
public is depending on the SACC to provide the honest
and hard-hitting feedback that EPA needs in order to do
its job correctly and fully examine the impact of this
deadly chemical.
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EPA/OPPT Response
• There are three other dockets from 2017-2020 with a lot
of evidence that reiterate our concerns listed above.
EPA should not ignore the concerns expressed by the
public.
11.3 Withdraw draft and issue a revised Draft RE for Asbestos
77, 85,
86, 111
PUBLIC COMMENTS:
• Commenters urged EPA to withdraw the current Draft
RE for Asbestos and address its shortcomings in a
revised risk evaluation for asbestos in which EPA
complies with its obligations under TSCA and the
Administrative Procedure Act.
EPA recognizes there are many perspectives on approaches
to conducting the risk evaluation for asbestos under TSCA.
EPA has described the approach it will take moving forward
in the Preamble that describes the current effort as Part 1
focused on chrysotile asbestos and that Part 2 will be
subsequently developed (scope document under development
now) and focus on legacy uses and associated disposals of
asbestos (including other fiber types).
12. Other
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Summary of Other Comments
EPA/OPPT Response
12.1 Agency should recognize impact of risk evaluation on tort/personal injury litigation
42, 74
PUBLIC COMMENTS:
• The document could have a dramatic impact on current
and future toxic tort litigation, which is important to
recognize.
• Agency documents are routinely used as evidence in
asbestos personal injury litigation, both as exhibits and
as reliance materials by expert witnesses. The document
if finalized as is puts EPA in the position of supporting
plaintiffs in asbestos litigation, by issuing a risk
evaluation that addresses only an illusory current COU.
Defendants in asbestos personal injury litigation will be
significantly and directly harmed by such a result,
forced to defend cases based upon the product-specific
science, and also explain how and why EPA's risk
evaluation process entirely disregarded that science,
In conducting risk evaluations under TSCA, EPA must meet
the statutory requirements of the law. Consideration of
personal injury litigation is outside the scope of these
requirements.
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Summary of Other Comments
EPA/OPPT Response
thus reaching an erroneous conclusion. Such harm can
be avoided and ameliorated only if EPA adheres to its
statutorily mandated objectivity and mission and is
equally careful to ensure that it permits no exceptions to
its conflict of interest requirements and follows the best
available science on the issue.
• EPA is legally obliged to be a neutral arbiter of
available relevant science in this and each of its risk
assessments. The fact that the Final Risk Evaluation will
have a significant impact on private litigation with
many stakeholders is reason for creating a risk
assessment process which provides a voice to the
positions of defendants as well as plaintiffs, and which
is based upon current applicable science, unimpaired by
the agenda of one set of litigants or the other.
12.2 EPA should expand the category for required notification to "any use" of asbestos
43
• Allowing new asbestos containing materials to be used
in construction will only increase the number of
workers (miners, manufacturers, construction trade
contractors, etc.) exposed to asbestos and lengthen the
potential exposure period, perhaps by decades. To even
consider allowing, even at times seemingly
encouraging, additional AC materials and products to be
used is counterproductive to the stated goals of the
EPA.
EPA finalized an Asbestos Significant New Use Rule
(SNUR) under TSCA Section 5 on April 25, 2019 that
prohibits manufacture (including import) or processing of
discontinued uses of asbestos from restarting without EPA
evaluating and making a determination on whether the
chemical presents unreasonable risks to health or the
environment and to take regulatory action, as appropriate,
under section 5.
12.3 Concern about feasibility for timely review of risk evaluation or SNUR application
109, 43
PUBLIC COMMENTS:
• The SNUR requires that all entities notify EPA days
before commencing any manufacturing. Given the
latency period of 10 to 30 years and the dose-response
relationship of asbestos and the difficulty determining
the nature and means of exposure, is it feasible to
review an application in within this timeframe?
Information on the requirements and procedures for notices
submitted under the SNUR for Asbestos is provided in that
specific rulemaking. The Docket ID for this rulemaking is
EPA-HQ-OPPT-2018-0159 and the rule was published in
the FR (84 FR 17345).
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• EPA requires manufacturers to submit notification at
least 90 days before manufacturing an asbestos-
containing product. The SNUR implies that the EPA
cannot use historic data to evaluate the new product.
This begs the question, "How can the EPA conduct a
rigorous review of a new product in only 90 days?"
12.4 State interest in ensuring Draft RE for Asbestos is conducted in accordance with TSCA
77
PUBLIC COMMENTS:
• State commenters expressed a significant interest in
ensuring that the risk evaluation for asbestos is
conducted in accordance with TSCA. They cited state
regulations, new cases of mesothelioma, associated
deaths, and exposure sources in their states. The
commenting states included Massachusetts, California,
Maryland, Minnesota, New York, Oregon, and
Washington State.
EPA is confident that Risk Evaluations for the First 10
Chemicals completed under TSCA meet the statutory
requirements. EPA considered and evaluated reasonably
available information and considered comments from the
public and the SACC on its evaluation and conclusions.
EPA is aware of state regulations on asbestos, but these do
not have bearing on mandates required of EPA under
TSCA.
12.5 Not prudent to burden the chlor-alkali industry while responding to COVID
42
PUBLIC COMMENTS:
• During the peak of the COVID-19 crisis, it would not
seem to be a prudent time to be placing further
constraints on the chlor-alkali industry that produces the
most widely used disinfectant (chlorine), when the data
shows that the workers are not over-exposed to asbestos
(based upon the OSHA PEL).
EPA has conducted Part 1 of the Risk Evaluation for
Asbestos focused on chrysotile asbestos according to the
statutory requirements and timelines required under TSCA.
EPA will initiate risk management action to address
unreasonable risks identified in Part 1 of the Risk
Evaluation, and the public will have an opportunity to
comment on any proposed rulemaking under TSCA section
6(a).
12.6 EPA's narrow scope of evaluation for asbestos should not be a template for future risk evaluation
25,45
PUBLIC COMMENTS:
• EPA's narrow scope of evaluation for asbestos should
not be used as a template for future risk evaluation by
EPA because it has been hastily crafted and is designed
to underestimate risk. Even with the narrowing of the
scope of the risk evaluation and the resulting
underestimating of the risk of exposure to asbestos,
Since TSCA was amended in 2016, EPA has worked
expeditiously to conduct risk evaluations for the First 10
Chemicals according to the statutory deadlines while
meeting all requirements of the law. As a part of these risk
evaluations, EPA has received a wealth of input from the
public and from the SACC that will lead to refinements and
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EPA still arrives at the conclusion that asbestos poses an
unreasonable risk in most COUs. Streamlining should
not be used in other evaluations, just because it makes
the process of risk evaluation easier for EPA.
• It is concerning that what EPA does here to estimate
risk will be the template for all other US assessments
and perhaps international ones as well. EPA has
admittedly used methods and template that might
underestimate the risk of asbestos related deaths. Since
EPA is looked to as an authority on risk assessments, it
is important that its methodology is fair, not erring on
the low side of asbestos exposure, asbestos cancer and
asbestos deaths.
improvements in the processes used to develop risk
evaluations under TSCA.
12.7 EPA should continue to support asbestos regulations
29
PUBLIC COMMENTS:
• EPA should ensure that it continues to support all its
Asbestos Hazard Emergency Response Act (AHERA)
and Asbestos School Hazard Abatement
Reauthorization Act (ASHARA) regulations concerning
the risks posed in the management and abatement of
ACBMs including legacy ACBMs.
AHERA and ASHARA regulations are rules established
before, and are independent of, the amended TSCA and are
not impacted by the implementation of risk evaluation and
risk management under TSCA.
12.8 Insurance coverage for medical surveillance for asbestos-exposed people
15, 17,
29, 30
PUBLIC COMMENTS:
• Commenters asked EPA to work with OSHA, NIOSH
and ILO to forge ahead with affordable, insurance-
covered low dose CT scanning for medical surveillance
of persons with exposures, where appropriate,
particularly for laborers exposed to fiber releases from
ACBMs from buildings (e.g, schools). In 2017, the
CDC released its meta-study showing an increase in
mesothelioma in construction type trades from 1999 to
2015.
• Commenter suggested pushing OSHA, NIOSH, and
ILO to lobby Congress to provide insurance coverage
EPA's obligations and requirements under TSCA and its
risk evaluation for asbestos do not pertain to insurance
coverage or medical surveillance.
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for low dose CT scanning and medical surveillance for
asbestos-exposed workers and residents of buildings
where legacy ACBMs are present.
12.9 Consider Canada's regulatory approach for asbestos
68
PUBLIC COMMENTS:
• Commenter outlined how Canada regulated asbestos. A
similar action by EPA would meet the very limited
mandate of the current task and does not require a new
risk assessment.
As noted in the Scope and Problem Formulation documents
for Asbestos, EPA ascertained all the international laws and
regulations pertaining to Asbestos (Appendix A-3 in each
document). EPA reviewed these laws and regulations to
inform its consideration of approaches to conducting the
risk evaluation and subsequent risk management.
12,10 Availability of information on consumer products and associated manufacturers
109
PUBLIC COMMENTS:
• Will you be able to separately list the new consumer
products anticipated to entering the market based on the
risk evaluation and the SNUR?
• Who are the anticipated manufacturers of these
construction, manufacturing, wholesale trade and
transportation entities and the current political
affiliation and of these entities?
For more information on the SNUR, please review the
specific rulemaking documents. The Docket ID for this
rulemaking is EPA-HQ-OPPT-2018-0159 and the rule was
published in the FR (84 FR 17345). Since finalization of the
asbestos SNUR in 2019, EPA has not received any
significant new use notices. EPA is not aware of
manufacturers that may anticipate submitting a notice under
the SNUR.
12.11 Research for worker conditions in asbestos mines outside of U.S.
43
PUBLIC COMMENTS:
• Although there are no active asbestos mines in the US at
this time, someone has to mine the asbestos, package it,
and ship it to us for our use. The U.S. has rules and
programs that look at ensuring products sold in the U.S.
are not manufactured in other countries using child
labor or sweat shops, where worker safety is
compromised in the name of profit. Has the EPA done
any research on the conditions and exposures workers
must endure when working in asbestos mines?
The questions raised in this public comment are outside the
scope of TSCA risk evaluations and the associated statutory
requirements that EPA must meet.
Page 265 of 284
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