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EPA Document# EPA-740-D-24-020
December 2024
Office of Chemical Safety and
Pollution Prevention
Draft Risk Evaluation for Dicyclohexyl Phthalate
(DCHP)
CASRN 84-61-7
SEPA
United States
Environmental Protection Agency
December 2024
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS 8
EXECUTIVE SUMMARY 9
1 INTRODUCTION 13
1.1 Scope of the Risk Evaluation 13
1.1.1 Life Cycle and Production Volume 15
1.1.2 Conditions of Use Included in the Risk Evaluation 18
1.1.2.1 Conceptual Models 20
1.1.3 Populations and Durations of Exposure Assessed 26
1.1.3.1 Potentially Exposed and Susceptible Subpopulations 26
1.2 Organization of the Risk Evaluation 27
2 CHEMISTRY AND FATE AND TRANSPORT OF DCHP 28
2.1 Summary of Physical and Chemical Properties 28
2.2 Summary of Environmental Fate and Transport 29
3 RELEASES AND CONCENTRATIONS OF DCHP IN THE ENVIRONMENT 30
3.1 Approach and Methodol ogy 30
3.1.1 Manufacturing, Processing, Industrial and Commercial Use 30
3.1.1.1 Crosswalk of Conditions of Use to Occupational Exposure Scenarios 30
3.1.1.2 Description of DCHP Use for Each OES 32
3.1.2 Estimating the Number of Release Days per Year for Facilities in Each OES 33
3.1.3 Daily Release Estimation 35
3.1.4 Consumer Down-the-Drain and Landfills 36
3.2 Summary of Environmental Releases 37
3.2.1 Manufacturing, Processing, Industrial and Commercial 37
3.2.2 Weight of Scientific Evidence Conclusions for Environmental Releases from Industrial and
Commercial Sources 43
3.2.3 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the Environmental
Release Assessment 52
3.3 Summary of Concentrations of DCHP in the Environment 53
3.3.1 Weight of Scientific Evidence Conclusions 54
3.3.1.1 Surface Water 54
3.3.1.2 Ambient Air 55
4 HUMAN HEALTH RISK ASSESSMENT 56
4.1 Summary of Human Exposures 56
4.1.1 Occupational Exposures 57
4.1.1.1 Approach and Methodol ogy 57
4.1.1.2 Summary of Number of Workers and ONUs 61
4.1.1.3 Summary of Inhalation Exposure Assessment 63
4.1.1.4 Summary of Dermal Exposure Assessment 65
4.1.1.5 Weight of Scientific Evidence Conclusions for Occupational Exposure 67
4.1.1.5.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
Occupational Exposure Assessment 79
4.1.2 Consumer Exposures 80
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4.1.2.1 Summary of Consumer and Indoor Dust Exposure Scenarios and Modeling
Approach and Methodology 80
4.1.2.2 Modeling Dose Results by COU for Consumer and Indoor Dust 85
4.1.2.3 Weight of Scientific Evidence Conclusions for Consumer Exposure 86
4.1.2.3.1 Strength, Limitations, Assumptions, and Key Sources of Uncertainty for the
Consumer Exposure Assessment 86
4.1.3 General Population Exposures to Environmental Releases 89
4.1.3.1 General Population Screening Level Exposure Assessment Results 92
4.1.3.1 Overall Confidence in General Population Screening Level Exposure Assessment 96
4.1.4 Human Milk Exposures 96
4.1.5 Aggregate and Sentinel Exposure 97
4.2 Summary of Human Health Hazards 97
4.2.1 Background 97
4.2.2 Non-cancer Human Health Hazards of DCHP 97
4.2.3 Cancer Human Health Hazards of DCHP 99
4.3 Human Health Risk Characterization 100
4.3.1 Risk Assessment Approach 100
4.3.1.1 Estimation of Non-cancer Risks from Exposure to DCHP 102
4.3.1.2 Estimation of Non-cancer Aggregate Risks from Exposure to DCHP 102
4.3.2 Risk Estimates for Workers 103
4.3.2.1 Overall Confidence in Worker Risk Estimates for Individual DCHP COUs 115
4.3.3 Risk Estimates for Consumers 125
4.3.3.1 Overall Confidence in Consumer Risks 127
4.3.4 Risk Estimates for General Population Exposed to DCHP through Environmental Releases
130
4.3.4.1 Overall Confidence in General Population Screening Level Exposure Assessment... 133
4.3.5 Risk Estimates for Potentially Exposed or Susceptible Subpopulations 133
4.4 Human Health Cumulative Risk Assessment and Characterization 134
4.4.1 Hazard Rel ative Potency 136
4.4.1.1 Relative Potency Factor Approach Overview 136
4.4.1.2 Relative Potency Factors 137
4.4.2 Cumulative Phthalate Exposure: Non-attributable Cumulative Exposure to DEHP, DBP,
BBP, DIBP, and DINP Using NHANES Urinary Biomonitoring and Reverse Dosimetry 139
4.4.2.1.1 Weight of Scientific Evidence: Non-attributable Cumulative Exposure to
Phthalates 140
4.4.3 Estimation of Risk Based on Relative Potency 147
4.4.4 Risk Estimates for Workers Based on Relative Potency 149
4.4.4.1 Overall Confidence in Cumulative Worker Risk Estimates 152
4.4.5 Risk Estimates for Consumers Based on Relative Potency 158
4.4.5.1 Overall Confidence in Cumulative Consumer Risks 158
4.4.6 Cumulative Risk Estimates for the General Population 161
4.5 Comparison of Single Chemical and Cumulative Risk Assessments 161
5 ENVIRONMENTAL RISK ASSESSMENT 164
5.1 Summary of Environmental Exposures 164
5.2 Summary of Environmental Hazards 165
5.3 Environmental Risk Characterization 166
5.3.1 Risk Assessment Approach 166
5.3.2 Risk Estimates for Aquatic and Terrestrial Species 166
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115 5.3.3 Overall Confidence and Remaining Uncertainties Confidence in Environmental Risk
116 Characterization 171
117 6 UNREASONABLE RISK DETERMINATION 173
118 6.1 Human Health 175
119 6.1.1 Populations and Exposures EPA Assessed for Human Health 176
120 6.1.2 Summary of Human Health Effects 176
121 6.1.3 Basis for Unreasonable Risk to Human Health 177
122 6.1.4 Workers 179
123 6.1.5 Consumers 183
124 6.1.6 General Population 183
125 6.2 Environment 185
126 6.2.1 Populations and Exposures EPA Assessed for the Environment 186
127 6.2.2 Summary of Environmental Effects 186
128 6.2.3 Basis for No Unreasonable Risk of Injury to the Environment 187
129 6.3 Additional Information Regarding the Basis for Unreasonable Risk 188
130 REFERENCES 196
131 APPENDICES 208
132 Appendix A KEY ABBREVIATIONS AND ACRONYMS 208
133 Appendix B REGULATORY AND ASSESSMENT HISTORY 210
134 B.l Federal Laws and Regulations 210
135 B,2 State Laws and Regulations 211
136 B.3 International Laws and Regulations 211
137 B.4 Assessment History 212
138 Appendix C LIST OF TECHNICAL SUPPORT DOCUMENTS 214
139 Appendix D UPDATES TO THE DCHP CONDITIONS OF USE TABLE 217
140 Appendix E CONDITIONS OF USE DESCRIPTIONS 221
141 5.1 Manufacturing - Domestic Manufacturing 221
142 E.2 Manufacturing - Importing 221
143 E,3 Processing - Incorporation into Formulation, Mixture, or Reaction Product - Adhesive and
144 Sealant Chemicals in Adhesive Manufacturing 222
145 E.4 Processing - Incorporation into Formulation, Mixture, or Reaction Product - Plasticizer
146 (Adhesive Manufacturing; Paint and Coating Manufacturing; Plastic Material and Resin
147 Manufacturing; Plastics Product Manufacturing; Printing Ink Manufacturing; and Ruber
148 Product Manufacturing) 222
149 E.5 Processing - Incorporation into Formulation, Mixture, or Reaction Product - Stabilizing
150 Agent (Adhesive Manufacturing; Asphalt Paving, Roofing, and Coating Materials
151 Manufacturing; Paints and Coating Manufacturing; and Plastics Product Manufacturing) 223
152 E.6 Processing - Incorporation into Articles - Plasticizer (Plastics Product Manufacturing and
153 Rubber Product Manufacturing) 224
154 E.7 Processing - Repackaging (e.g., Laboratory Chemical) 224
155 E.8 Processing - Recycling 224
156 E.9 Distribution in Commerce 225
157 E, 10 Industrial Use - Adhesive and Sealants (e.g., Computer and Electronic Product
158 Manufacturing; Transportation Equipment Manufacturing) 225
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E, 11 Industrial Use - Finishing Agent - Cellulose Film Production 225
E. 12 Industrial Use - Inks, Toner, and Colorant Products 225
E. 13 Industrial Use - Paints and Coatings 226
E. 14 Industrial Use - Other Articles with Routine Direct Contact During Normal Use Including
Rubber Articles; Plastic Articles (Hard) (e.g., Transportation Equipment Manufacturing).... 227
E. 15 Commercial Use - Adhesives and Sealants 227
E, 16 Commercial Use - Building/Construction Materials Not Covered Elsewhere 228
E. 17 Commercial Use - Ink, Toner, and Colorant Products 228
E.l 8 Commercial Use - Laboratory Chemicals 229
E. 19 Commercial Use - Paints and Coatings 229
E,20 Commercial Use - Other Articles with Routine Direct Contact During Normal Use
Including Rubber Articles; Plastic Articles (Hard) 231
E,21 Consumer Use - Adhesives and Sealants 231
E.22 Consumer Use - Other Articles with Routine Direct Contact During Normal Use Including
Rubber Articles; Plastic Articles (Hard) 232
E.23 Consumer Use - Other Consumer Articles that Contain DCHP from: Inks, Toner, and
Colorants; Paints and Coatings; and Adhesives and Sealants 233
E.24 Disposal 234
Appendix F DRAFT OCCUPATIONAL EXPOSURE VALUE DERIVATION 235
F.l Draft Occupational Exposure Value Calculations 235
LIST OF TABLES
Table 1-1. Categories and Subcategories of Use and Corresponding Exposure Scenario in the Draft Risk
Evaluation for DCHP 18
Table 2-1. Physical and Chemical Properties of DCHP 28
Table 3-1. Crosswalk of Conditions of Use to Assessed Occupational Exposure Scenarios 31
Table 3-2. Description of the Use of DCHP for Each OES 32
Table 3-3. Generic Estimates of Number of Operating Days per Year for Each OES 33
Table 3-4. Summary of EPA's Daily Release Estimates for Each OES and EPA's Overall Confidence in
these Estimates 38
Table 3-5. Summary of Overall Confidence in Environmental Release Estimates by Occupational
Exposure Scenario 44
Table 3-6. Summary of High-End DCHP Concentrations in Various Environmental Media from
Environmental Releases 54
Table 4-1. Summary of Exposure Monitoring and Modeling Data for Occupational Exposure Scenarios
59
Table 4-2. Summary of Total Number of Workers and ONUs Potentially Exposed to DCHP for Each
OES 61
Table 4-3. Summary of Average Adult Worker Inhalation Exposure Results for Each Occupational
Exposure Scenario 64
Table 4-4. Summary of Average Adult Worker Dermal Exposure Results for Each OES 66
Table 4-5. Summary of Assumptions, Uncertainty, and Overall Confidence in Exposure Estimates by
OES 68
Table 4-6. Summary of Consumer COUs, Exposure Scenarios, and Exposure Routes 83
Table 4-7. Weight of Scientific Evidence Summary per Consumer Condition of Use 88
Table 4-8. Exposure Scenarios Assessed in General Population Screening Level Analysis 92
Table 4-9. Summary of the Highest Doses in the General Population through Surface and Drinking
Water Exposure 94
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Table 4-10. Summary of the Highest Doses for Fish Ingestion for Adults in Tribal Populations 95
Table 4-11. General Population Ambient Air Exposure Summary 95
Table 4-12. Non-cancer HECs and HEDs Used to Estimate Risks 99
Table 4-13. Exposure Scenarios, Populations of Interest, and Hazard Values 100
Table 4-14. Occupational Aggregate Risk Summary Table for DCHP 116
Table 4-15. Consumer Risk Summary Table 128
Table 4-16. Summary of the Highest Doses for General Population through Surface and Drinking Water
Exposure 131
Table 4-17. Fish Ingestion for Adults in Tribal Populations Summary 132
Table 4-18. General Population Ambient Air Exposure Summary 132
Table 4-19. Draft Relative Potency Factors Based on Decreased Fetal Testicular Testosterone 138
Table 4-20. Cumulative Phthalate Daily Intake (|ig/kg-day) Estimates for Women of Reproductive Age,
Male Children, and Male Teenagers from the 2017-2018 NHANES Cycle 141
Table 4-21. Cumulative Phthalate Daily Intake (|ig/kg-day) Estimates for Women of Reproductive Age
(16-49 years old) by Race and Socioeconomic Status from the 2017-2018 NHANES
Cycle 143
Table 4-22. Risk Summary Table for Female Workers of Reproductive Age Using the RPF Analysis 153
Table 4-23. Consumer Cumulative Risk Summary Table 159
Table 5-1. Relevant Exposure Pathway to Receptors and Corresponding Risk Assessment for the DCHP
Environmental Risk Characterization 167
Table 6-1. Example of Occupational Risk Estimates for OES Manufacturing (Female Workers of
Reproductive Age and Benchmark MOE = 30) 180
Table 6-2. Example of Occupational Risk Estimates for OES Applications of Paints and Coatings
(Female Workers of Reproductive Age and Benchmark MOE = 30) 182
Table 6-3. Supporting Basis for the Draft Unreasonable Risk Determination for Human Health
(Occupational COUs) 189
LIST OF FIGURES
Figure 1-1. TSCA Existing Chemical Risk Evaluation Process 13
Figure 1-2. Draft Risk Evaluation Document Summary Map 15
Figure 1-3. DCHP Life Cycle Diagram 17
Figure 1-4. DCHP Conceptual Model for Industrial and Commercial Activities and Uses: Potential
Exposure and Hazards 22
Figure 1-5. DCHP Conceptual Model for Consumer Activities and Uses: Potential Exposures and
Hazards 23
Figure 1-6. DCHP Conceptual Model for Environmental Releases and Wastes: General Population
Hazards 24
Figure 1-7. DCHP Conceptual Model for Environmental Releases and Wastes: Ecological Exposures
and Hazards 25
Figure 3-1. An Overview of How EPA Estimated Daily Releases for Each OES 36
Figure 4-1. Approaches Used for Each Component of the Occupational Assessment for Each OES 58
Figure 4-2. Potential Human Exposure Pathways to DCHP Environmental Releases for the General
Population 90
LIST OF APPENDIX TABLES
Table_Apx B-l. Federal Laws and Regulations 210
Table_Apx B-2. State Laws and Regulations 211
Table_Apx B-3. International Laws and Regulations 211
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255 Table_Apx B-4. Assessment History of DCHP 212
256 TableApx D-l. Additions and Name Changes to Categories and Subcategories of Conditions of Use
257 Based on CDR Reporting and Stakeholder Engagement 217
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ACKNOWLEDGEMENTS
The Assessment Team gratefully acknowledges the participation, input, and review comments from U.S.
Environmental Protection Agency (EPA or the Agency) Office of Pollution Prevention and Toxics
(OPPT) and Office of Chemical Safety and Pollution Prevention (OCSPP) senior managers and science
advisors. This draft was also reviewed by Agency colleagues in the Office of Air Quality Planning and
Standards (OAQPS) and Office of Research and Development (ORD). The Agency also gratefully
acknowledges assistance from EPA contractors ERG (Contract No. 68HERD20A0002 and GS-00F-
079CA); ICF (Contract No. 68HERC23D0007); and SRC, Inc. (Contract No. 68HERH19D0022).
Docket
Supporting information can be found in the public docket, Docket ID (EPA-HQ-QPPT-2018-0504).
Disclaimer
Reference herein to any specific commercial products, process, or service by trade name, trademark,
manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring
by the United States Government.
Authors: Lillie Barnett (Assessment Co-Lead and Human Health Hazard Assessment Lead), Yashfin
Mahid (Assessment Co-Lead and Engineering Assessment Co-Lead), Catherine Ngo (General
Population Exposure Assessment Lead), Randall Bernot (Environmental Hazard Assessment Lead),
Laura Krnavek (Consumer and Indoor Dust Exposure Assessment Lead), J. Aaron Murray (Engineering
Assessment Co-Lead), Grant Goedjen (Physical and Chemical Assessment Lead and Fate Assessment
Lead), Claire Brisse (Risk Determination Lead), Rochelle Bohaty (Branch Supervisor), Collin Beachum
(Branch Supervisor), Marc Edmonds (Branch Supervisor), Jennifer Brennan (past Assessment Lead),
John Allran, Andrea Amati, Maiko Arashiro, Sean Duenser, Victoria Ellenbogen, Bryan Groza,
Christelene Horton, Robert Landolfi, Anthony Luz, and Kevin Vuilleumier.
Contributors: Yousuf Ahmad, Ballav Aryal, Amy Benson, Odani Bowen, Nicholas Castaneda, Maggie
Clark, Jone Corrales, Daniel DePasquale, Patricia Fontenot, Lauren Gates, Myles Hodge, Brandall
Ingle-Carlson, Keith Jacobs, June Kang, Grace Kaupas, Edward Lo, Yadi Lopez, Kelsey Miller, Ashley
Peppriell, Kelley Stanfield, Alex Smith, Cory Strope, Ryan Sullivan, Joseph Valdez, Leora Vegosen,
Jason Wight, and Susanna Wegner.
Technical Support: Mark Gibson, Emily Griffin, Hillary Hollinger, Brandall Ingle-Carlson, and S.
Xiah Kragie.
This draft risk evaluation was reviewed and cleared for release by OPPT and OCSPP leadership.
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EXECUTIVE SUMMARY
Background
EPA has evaluated the health and environmental risks of the chemical dicyclohexyl phthalate (DCHP)
under the Toxic Substances Control Act (TSCA). In this draft risk evaluation, EPA has preliminarily
determined that DCHP presents an unreasonable risk of injury to human health under the
conditions of use (COUs). Of the 24 COUs that the Agency evaluated, 9 COUs have risk estimates that
raise concerns for workers' exposure to DCHP; no COUs raise such concerns for consumers or the
general population. In this draft evaluation, EPA's protective, screening4evel approaches demonstrated
that DCHP does not pose an unreasonable risk of injury to the environment. After this draft risk
evaluation is informed by public comment and independent, expert peer review, EPA will issue a final
risk evaluation that includes its determination as to whether DCHP presents unreasonable risk to human
health or the environment under the TSCA COUs.
DCHP is used primarily as a plasticizer in manufacturing adhesives, paints and coatings, plastic
products, rubber products, and plastic resins. It is also used as a stabilizing agent in the manufacturing of
adhesives, paint and coatings, plastic products, printing ink, rubber products, as well as plastic material
and resin. Other uses of DCHP include industrial use in transportation equipment, computer, and
electronic product manufacturing and commercial use in building/construction materials and laboratory
chemicals—all of which are COUs. Workers may be exposed to DCHP when making these products or
otherwise using DCHP in the workplace. When it is manufactured or used to make products, DCHP can
be released into water, where because of its properties, most will end up in the sediment at the bottom of
lakes and rivers. If released into the air, DCHP will attach to dust particles and be deposited on land or
into water. Indoors, DCHP has the potential over time to be released from products and adhere to dust
particles. If it does, people could inhale or ingest dust that contains DCHP.
Laboratory animal studies have been conducted to study DCHP to determine whether it causes a range
of non-cancer health effects on people. After reviewing the available studies, the Agency concludes that
there is strong evidence that DCHP causes developmental toxicity (a non-cancer human health hazard).
The most sensitive adverse developmental effects include effects on the developing male reproductive
system consistent with a disruption of androgen action—what is known as phthalate syndrome, which
results from decreased fetal testicular testosterone.
EPA is including DCHP for cumulative risk assessment (CRA) along with five other phthalate
chemicals that also cause effects on laboratory animals consistent with phthalate syndrome (U.S. EPA.
2023c). Notably, assessments by Health Canada, U.S. Consumer Product Safety Commission (U.S.
CPSC), European Chemicals Agency (ECHA), and the Australian National Industrial Chemicals
Notification and Assessment Scheme (NICNAS) have reached similar conclusions regarding the
developmental effects of DCHP. They have also conducted CRAs of phthalates based on these
chemicals' shared ability to cause phthalate syndrome. Further, independent, expert peer reviewers
endorsed EPA's proposal to conduct a CRA of phthalates under TSCA during the May 2023 meeting of
the Science Advisory Committee on Chemicals (SACC) because doing so represents the best available
science. In this draft risk evaluation, the Agency has evaluated cumulative exposure to phthalates for the
U.S. civilian population using human biomonitoring data. Note that these phthalate exposures to the
general civilian population cannot be attributed to specific TSCA COUs or other sources. This non-
attributable cumulative exposure and risk, representing the national population, was taken into
consideration by EPA in reaching its preliminary determination of unreasonable risk of injury of human
health for DCHP. Had EPA not taken this into consideration, it could have understated the unreasonable
risk of injury to human health for DCHP.
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In December 2019, EPA designated DCHP as a high-priority substance for TSCA risk evaluation and in
August 2020 released the final scope of the risk evaluation (U.S. EPA. 2020b). This draft risk evaluation
assesses human health risk to workers, including occupational non-users (ONUs), consumers, and the
general population exposed to environmental releases. It also assesses risk to the environment.
Manufacturers report DCHP production volumes through the Chemical Data Reporting (CDR) rule
under the associated CAS Registry Number (CASRN) 84-61-7. The production volume for DCHP was
between 500,000 and 1,000,000 lb in 2019 based on the latest 2020 CDR data (EPA describes
production volumes as a range to protect confidential business information). The Agency has evaluated
DCHP across its TSCA COUs, ranging from manufacture to disposal.
Past assessments of DCHP from other government agencies that addressed a broad range of uses, which
may have included TSCA and non-TSCA uses, have concluded that DCHP does not pose risk to human
health or the environment based on its concentration in products and the environment. Notably, both the
U.S. CPSC's and Health Canada's risk assessments included consideration of exposure from children's
products as well as from other sources such as personal care products, diet, consumer products, and the
environment. However, these past assessments did not specifically consider exposure to workers. In this
draft assessment, EPA comes to the same general conclusions of those assessments with regard to risk to
consumers and the general population—with the exception of where it evaluated and has identified risks
to workers with some manufacturing and processing uses of DCHP.
In this draft risk evaluation, EPA evaluated risks resulting from exposure to DCHP from facilities that
use, manufacture, or process DCHP under industrial and/or commercial COUs subject to TSCA and the
products resulting from such manufacture and processing. Human or environmental exposure to DCHP
through uses that are not subject to TSCA (e.g., use in cosmetics, medical devices, food contact
materials) were not specifically evaluated by the Agency in reaching its preliminary determination of
unreasonable risk to injury of human health. This is because these uses are excluded from TSCA's
definition of chemical substance. Thus, although EPA is preliminarily determining in this draft risk
evaluation that nine specific TSCA COUs significantly contribute to its draft unreasonable risk finding
for DCHP, this determination cannot be extrapolated to form conclusions about uses of DCHP that are
not subject to TSCA and that EPA did not evaluate.
Determining Unreasonable Risk to Human Health
EPA's TSCA existing chemical risk evaluations must determine whether a chemical substance does or
does not present unreasonable risk to human health or the environment under its TSCA COUs. The
unreasonable risk must be informed by the best available science. The Agency, in making the finding of
presents unreasonable risk to human health, considers risk-related factors as described in its risk
evaluation framework rule. Risk-related factors beyond the levels of DCHP that can cause specific
health effects include but are not limited to the type of health effect under consideration, the reversibility
of the health effect being evaluated, exposure-related considerations (e.g., duration, magnitude,
frequency of exposure), population exposed (including any potentially exposed or susceptible
subpopulations), and EPA's confidence in the information used to inform the hazard and exposure
values. These considerations must be included as part of a pragmatic and holistic evaluation of hazard
and exposure to DCHP. If an estimate of risk for a specific scenario exceeds the standard risk
benchmarks, then the formal determination of whether those risks significantly contribute to the
unreasonable risk of DCHP under TSCA must be both case-by-case and context-driven.
EPA evaluated the risks to people from being exposed to DCHP at work, indoors, and outdoors. In its
human health evaluation, the Agency used a combination of screening-level and more refined
approaches to assess how people might be exposed to DCHP through breathing or ingesting dust or
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other particulates, as well as through skin contact. EPA has also authored a draft cumulative risk
technical support document including DCHP and five other phthalate chemicals that all cause the same
health effect—phthalate syndrome. The CRA takes into consideration differences in the ability of each
phthalate to cause effects on the developing male reproductive system. Use of this "relative potency"
across all the phthalates EPA is reviewing that cause phthalate syndrome provides a more robust risk
assessment of DCHP as well as a common basis for adding risk across the six phthalates included in the
cumulative assessment. Thus, risks are characterized for occupational and consumer exposures to
DCHP, alone as well as in combination with the measured cumulative phthalate exposure that is
experienced by the U.S. population and that cannot be attributed to a specific use.
In determining whether DCHP presents an unreasonable risk of injury to human health, EPA considered
the following potentially exposed and susceptible subpopulations (PESS) in its assessment: women of
reproductive age, pregnant women, infants, children and adolescents, people who frequently use
consumer products and/or articles containing high concentrations of DCHP, people exposed to DCHP in
the workplace, people in proximity to releasing facilities, including fenceline communities, and Tribes
and subsistence fishers whose diets include large amounts of fish. These subpopulations are PESS
because some have greater exposure to DCHP per body weight (e.g., infants, children, adolescents)
while others may experience exposure from multiple sources or higher exposures than others. EPA's
robust screening analysis preliminarily finds that exposure of consumers and of the general population to
DCHP does not contribute to unreasonable risk of injury to human health. However, the Agency
preliminarily identified nine COUs where occupational exposure for workers significantly contributes to
the unreasonable risk of injury to human health.
Summary, Considerations, and Next Steps
EPA is preliminarily determining the following COUs, based on the DCHP individual analysis and the
relative potency factor analysis, significantly contribute to the unreasonable risk to workers:
• Manufacturing - domestic manufacturing;
• Processing - incorporation into formulation, mixture, or reaction product - adhesive and sealant
chemicals in adhesive manufacturing;
• Processing - incorporation into formulation, mixture, or reaction product - plasticizer (adhesive
manufacturing; paint and coating manufacturing; and printing ink manufacturing);
• Processing - incorporation into formulation, mixture, or reaction product - stabilizing agent
(adhesive manufacturing; asphalt paving, roofing, and coating materials manufacturing; and
paints and coating manufacturing);
• Industrial use - finishing agent - cellulose film production;
• Industrial use - inks, toner, and colorant products (e.g., screen printing ink);
• Industrial use - paints and coatings;
• Commercial use - inks, toner, and colorant products (e.g., screen printing ink); and
• Commercial use - paints and coatings.
EPA is preliminarily determining that the following COUs do not significantly contribute to the
unreasonable risk:
• Manufacturing - importing;
• Processing - incorporation into article - plasticizer in plastics product manufacturing and rubber
product manufacturing;
• Processing - repackaging (e.g., laboratory chemicals);
• Processing - recycling;
• Distribution in commerce;
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• Industrial use - adhesives and sealants (e.g., computer and electronic product manufacturing;
transportation equipment manufacturing);
• Industrial use - other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard) (e.g., transportation equipment manufacturing);
• Commercial use - adhesives and sealants;
• Commercial use - building/construction materials not covered elsewhere;
• Commercial use - laboratory chemicals;
• Commercial use - other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard);
• Consumer use - adhesives and sealants;
• Consumer use - other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard);
• Consumer use - other consumer articles that contain dicyclohexyl phthalate from: inks, toner,
and colorants; paints and coatings; adhesives and sealants (e.g., paper products, textiles, products
using cellulose film, etc.); and
• Disposal.
This risk evaluation has been released for public comment and will undergo independent, expert
scientific peer review. EPA will issue a final DCHP risk evaluation after considering input from the
public and peer reviewers. If in the final risk evaluation the Agency determines that DCHP presents
unreasonable risk to human health or the environment, EPA will initiate regulatory action so that DCHP
no longer presents such risk.
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1 INTRODUCTION
EPA has evaluated dicyclohexyl phthalate (DCHP) under the Toxic Substances Control Act (TSCA)
section 6(b). DCHP is primarily used as a plasticizer in polyvinyl chloride (PVC) in consumer,
commercial, and industrial applications—although it is also used in adhesives, sealants, paints, coatings,
rubbers, and non-PVC plastics as well as for other applications. Section 1.1 summarizes the scope of the
draft DCHP risk evaluation and provides information on production volume, a life cycle diagram (LCD),
conditions of use (COUs), and conceptual models used for DCHP. Section 1.2 presents the organization
of this draft risk evaluation.
Figure 1-1 describes the major inputs, phases, and outputs/components of the TSCA risk evaluation
process, from scoping to releasing the final risk evaluation.
Inputs
• Existing Laws, Regulations,
and Assessments
Use Document
Public Comments
Public Comments on
Draft Scope Document
Analysis Plan
Testing Results
Data Evaluation Process
Data Integration
Public Comments on
Draft RE
Peer Review Comments
on Draft RE
Phase
Outputs
Figure 1-1. TSCA Existing Chemical Risk Evaluation Process
1.1 Scope of the Risk Evaluation
EPA evaluated risk to humans and the environment for DCHP. Specifically for human populations, the
Agency evaluated risk to workers and occupational non-users (ONUs) via inhalation routes; risk to
workers via dermal routes; risk to ONUs via dermal routes for occupational exposure scenarios (OESs)
in mists and dusts; risk to consumers via inhalation, dermal, and oral routes; and risk to bystanders via
the inhalation route. Additionally, EPA considered the following potentially exposed and susceptible
populations (PESS) in its assessment—women of reproductive age, pregnant women, infants, children
and adolescents, people who frequently use consumer products and/or articles containing high-
concentrations of DCHP, people exposed to DCHP in the workplace, and Tribes and subsistence fishers
whose diets include large amounts of fish. As described further in Section 4.1.3, EPA assessed risks to
the general population, including considerations for fenceline populations, from environmental releases
using a screening-level analysis, which considered risk from exposure to DCHP via oral ingestion of
surface water, drinking water, fish, and soil from air to soil deposition. For environmental populations,
EPA evaluated risk to aquatic species via water, sediment, and air as well as risk to terrestrial species via
air, soil, sediment, and water.
Consistent with EPA's Draft Proposed Approach for Cumulative Risk Assessment (CRA) of High-
Prior ity Phthalate s and a Manufacturer-Re quested Phthalate under the Toxic Substances Control Act
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(U.S. EPA. 2023c). EPA has also authored a draft cumulative risk technical support document of DCHP
and five other toxicologically similar phthalates {i.e., diethylhexyl phthalate [DEHP], dibutyl phthalate
[DBP], diisobutyl phthalate [DIBP], butyl benzyl phthalate [BBP], and diisononyl phthalate [DINP])
that are also being evaluated under TSCA based on a common toxicological endpoint {i.e., phthalate
syndrome, which results from decreased fetal testicular testosterone). The cumulative analysis takes into
consideration differences in phthalate potency to cause effects on the developing male reproductive
system. Use of relative potency across the phthalates provides a more robust risk assessment of DCHP
and a common basis for adding risk across the cumulative chemicals. Numerous other regulatory
agencies—Health Canada, U.S. Consumer Product Safety Commission (U.S. CPSC), European
Chemicals Agency (ECHA), and the Australian National Industrial Chemicals Notification and
Assessment Scheme (NICNAS)—have assessed phthalates for cumulative risk, and EPA's proposal to
conduct a CRA of phthalates under TSCA was endorsed by the Science Advisory Committee on
Chemicals (SACC) as the best available science. As described further in Sections 4.4.4 and 4.4.5,
cumulative risk considerations focus on acute duration exposures to the most susceptible
subpopulations: female workers and consumers of reproductive age (16-49 years of age) as well as male
infants and male children (3-15 years of age) exposed to consumer products and articles.
The draft DCHP risk evaluation includes a series of technical support documents (TSD). Each TSD1
support document contains sub-assessments that inform adjacent, "downstream" technical support
documents. A basic diagram showing the layout and relationship of these assessments is provided below
in Figure 1-2. High-level summaries of each relevant technical support document are presented in this
risk evaluation. Detailed information for each technical support document can be found in the
corresponding documents. Appendix C incudes a list and citations for all technical support documents
and supplemental files included in the draft risk evaluation for DCHP.
These technical support documents leveraged the data and information sources already identified in the
Final Scope of the Risk Evaluation for Dicyclohexyl Phthalate (1,2-Benzenedicarboxylic acid, 1,2-
dicyclohexyl ester); CASRN84-61-7 (also referred to as "final scope document") (U.S. EPA. 2020b).
OPPT conducted a comprehensive search for "reasonably available information" to identify relevant
DCHP data for use in the draft risk evaluation. The approach used to identify specific relevant risk
assessment information was discipline-specific and is detailed in Draft Systematic Review Protocol for
Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024ag). or as otherwise noted in the relevant TSDs.
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Non-cancer Human Health
Hazard Assessment
Meta-Analysis and BMD
Modeling of Fetal Testicular
Testosterone for
for DEHP, DBP, BBP, DIBP, DCHP
Cancer Human Health
Hazard Assessment
for DEHP, DBP, DIBP, DCHP. BBP
Include biological PESS
Fate and Physical
Chemistry Assessment
Technical Support Document for
the Cumulative Risk Analysis of
DEHP, DBP, BBP, DIBP, DCHP, and
DINP under TSCA
Human & Environmental
Exposure Assessments
Environmental Media and
General Population and
Environmental Exposure
Assessment
Environmental Release
and Occupational
Exposure Assessment
Consumer and Indoor
Dust Exposure
Assessment
Include exposure PESS
Draft Risk Evaluation
Conditions of Use
Human Health
Risk Characterization
Includes PESS
Environmental Risk
Characterization
Unreasonable
Risk Determination
Environmental
Hazard Assessment
Chemical-specific systematic review protocol and data extraction files
Figure 1-2. Draft Risk Evaluation Document Summary Map
1.1.1 Life Cycle and Production Volume
The LCD shown in Figure 1-3 depicts the COUs that are within the scope of the risk evaluation, during
various life cycle stages, including manufacturing, processing, distribution, use (industrial, commercial,
consumer), and disposal. The LCD has been updated since its inclusion in the final scope document,
with consolidated and/or expanded processing and use steps. A complete list of updates and
explanations of the updates made to COUs for DCHP from the final scope document to this draft risk
evaluation is provided in Appendix D. The information in the LCD is grouped according to the
Chemical Data Reporting (CDR) processing codes and use categories (including functional use codes
for industrial uses and product categories for industrial and commercial uses). The CDR Rule under
TSCA section 8(a) (see 40 CFR part 711) requires certain U.S. manufacturers (including importers) to
provide EPA with information on the chemicals they manufacture or import into the United States. EPA
collects CDR data approximately every four years with the latest collections occurring in 2006, 2012,
2016, and 2020.
EPA included descriptions of the industrial, commercial, and consumer use categories identified from
the 2020 CDR in the LCD (Figure 1-3) (U.S. EPA. 2020a). The descriptions provide a brief overview of
the use category; the Draft Environmental Release and Occupational Exposure Assessment for
DicyclohexylPhthalate (U.S. EPA. 2024q) contains more detailed descriptions (e.g., process
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547 descriptions, worker activities, process flow diagrams, equipment illustrations) for each manufacturing,
548 processing, use, and disposal category.
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549
MFG/IMPORT
550
551
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553
Manufacture
(Including Import)
PROCESSING
Incorporation into formulation, mixture, or reaction product
Adkesives and sealant chemicals (adhesive manufacturing):
Plasticizer (adhesive manufacturing, paint and coating
manufacturing, plastics product manufacturing, printing ink
manufacturing, rubber product manufacturing, plastic material
and resin manufacturing); Stabilizing agent (plastics product
manufacturing: paint and coating manufacturing; asphalt paving,
roofing, and coating materials manufacturing; adhesive
manufacturing)
Incorporation into Article
Plasticizer (plastics product manufacturing; rubber product
manufacturing)
Repackaging (e.g., laboratory chemicals)
Recycling
Figure 1-3. DC HP Life Cycle Diagram
INDUSTRIAL, COMMERCIAL, CONSUMER USES
K>
Adhesives and sealants
Finishing agents
Building/construction materials not covered elsewhere
Inks, toner, and colorant products
Paints and coatings
Plastic and rubber products not covered elsewhere
Laboratory chemicals
RELEASES AND
WASTE DISPOSAL
See Conceptual Model
for Environmental
Releases and Wastes
Manufacture
(including import)
~
Processing
~
Uses:
1. Industrial/Commercial
2. Consumer
See Table 1-1 for categories and subcategories of COUs. Activities related to distribution (e.g., loading, unloading) will be considered throughout the
DCHP life cycle, as well as qualitatively through a single distribution scenario.
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The production volume for CASRN 84-61-7 in 2019 was between 500,000 and 1,000,000 pounds (lb) in
2019 based on the latest 2020 CDR data. EPA describes production volumes as a range to protect
production volume data claimed as confidential business information (CBI). For the 2020 CDR cycle,
collected data included the company name, volume of each chemical manufactured/imported, the
number of workers at each site, and information on whether the chemical was used in the commercial,
industrial, and/or consumer sector(s).
In the 2020 CDR, two sites reported production of DCHP. LANXESS reported a production volume of
17,290 lb for the 2019 CDR reporting year. The remaining site, Vertellus LLC, reported their production
volumes as CBI but also reported an export volume of 410,849 lb for 2019 and that 10 percent of their
PV was used as a plasticizer in adhesive manufacturing. EPA assumed that this site had no uses of
DCHP that are included under the reporting threshold and that 410,849 lb represented 90 percent of their
total PV. Therefore, EPA calculated the total manufactured PV from the site as 456,499 lb (410,849
0.9 = 456,499 lb or 207,064 kg). EPA was able to use this data and the number of reporting import sites
to estimate an average import volume per site.
1.1.2 Conditions of Use Included in the Risk Evaluation
The final scope document (U.S. EPA. 2020b) identified and described the life cycle stages, categories,
and subcategories that comprise TSCA COUs that EPA planned to consider in the risk evaluation. All
COUs for DCHP included in this draft risk evaluation are reflected in the LCD (Figure 1-3) and
conceptual models (Section 1.1.2.1). Table 1-1 below presents all COUs for DCHP.
In this draft risk evaluation, EPA made updates to the COUs listed in the final scope document (U.S.
EPA. 2020b). A complete list of updates and explanations of the updates made to COUs for DCHP from
the final scope document to this draft risk evaluation is provided in Appendix D.
Table 1-1. Categories and Subcategories of Use and Corresponding Exposure Scenario in the
Draft Risk Evaluation for DCHP
Life Cycle Stage"
Category6
Subcategoryc
Reference(s)
Manufacturing
Domestic manufacturing
Domestic manufacturing
(U.S. EPA. 2020a. 2019a)
Importing
Importing
(U.S. EPA. 2020a. 2019a)
Processing
Processing - incorporation
into formulation, mixture,
or reaction product
Adhesive and sealant chemicals in:
- Adhesive manufacturing
(U.S. EPA. 2019a)
Plasticizer in:
- Adhesive manufacturing
- Paint and coating manufacturing
- Plastic material and resin
manufacturing
- Plastics product manufacturing
- Printing ink manufacturing
- Rubber product manufacturing
(U.S. EPA. 2020a; ACA.
2019: AIA. 2019:
Carboline. 2019a. b;
MEMA. 2019; U.S. EPA.
2019a, d)
Stabilizing agent in:
- Adhesive manufacturing
- Asphalt paving, roofing, and
coating materials manufacturing
- Paint and coating manufacturing
- Plastics product manufacturing
(U.S. EPA. 2024ai:
Nourvon Chemicals LLC.
2020; U.S. EPA. 2020a;
AIA. 2019; U.S. EPA.
2019c)
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Life Cycle Stage"
Category6
Subcategoryc
Reference(s)
Processing - incorporation
into article
Plasticizer in:
- Plastics product manufacturing
- Rubber product manufacturing
(AIA. 2019: MEMA. 2019:
U.S. EPA. 2019a)
Repackaging
Repackaging (e.g., laboratory
chemical)
(U.S. EPA. 2020d)
Recycling
Recycling
(U.S. CPSC. 2015)
Distribution in
Commerce
Distribution in commerce
Distribution in commerce
Industrial Use
Adhesives and sealants
Adhesives and sealants (e.g.,
computer and electronic product
manufacturing; transportation
equipment manufacturing)
(Henkel. 2024: AIA. 2019:
Henkel. 2019: MEMA.
2019: Henkel. 2017)
Finishing agent
Cellulose film production
(U.S. EPA. 2020c:
Earthiustice. 2019)
Inks, toner, and colorant
products
Inks, toner, and colorant products
(e.g., screen printing ink)
(LANXESS. 2021: U.S.
EPA. 2021c. 2019e: Gans
Ink and Supplv. 2018)
Paints and coatings
Paints and coatings
(Carboline. 2019a. b: U.S.
EPA. 2019d)
Other articles with routine
direct contact during
normal use including
rubber articles; plastic
articles (hard)
Other articles with routine direct
contact during normal use
including rubber articles; plastic
articles (hard) (e.g., transportation
equipment manufacturing)
(AIA. 2019: MEMA.
2019)
Commercial Use
Commercial Use
Adhesives and sealants
Adhesives and sealants
Building/construction
materials not covered
elsewhere
Building/construction materials not
covered elsewhere
(LANXESS. 2021: U.S.
EPA. 2019a)
Inks, toner, and colorant
products
Inks, toner, and colorant products
(e.g., screen printing ink)
(LANXESS. 2021: U.S.
EPA. 2021c. 2019e: Gans
Ink and SuddIv. 2018)
Laboratory chemicals
Laboratory chemicals
(Restek Corporation. 2024:
Siama-Aldrich. 2024a. b:
NASA. 2020: U.S. EPA.
2020d: SPEX CertiPreo.
2019)
Paints and coatings
Paints and coatings
Other articles with routine
direct contact during
normal use including
rubber articles; plastic
articles (hard)
Other articles with routine direct
contact during normal use
including rubber articles; plastic
articles (hard)
(U.S. EPA. 2020a: AIA.
2019: MEMA. 2019: U.S.
EPA. 2019a)
Consumer Use
Adhesives and
sealants
Adhesives and
sealants
(DeWalt. 2024a: ITW
Permatex. 2024: Lord
Corporation. 2024:
Midwest Technology
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Life Cycle Stage"
Category6
Subcategoryc
Reference(s)
Products. 2024; MKT.
2024; ITW Permatex.
2021; DeWalt. 2020;
MKT. 2018: Lord
Corporation. 2017)
Other articles with routine
direct contact during
normal use including
rubber articles; plastic
articles (hard)
Other articles with routine direct
contact during normal use
including rubber articles; plastic
articles (hard)
(U.S. EPA. 2020a: AIA.
2019; MEMA. 2019; U.S.
EPA. 2019a)
Other
Other consumer articles that
contain dicyclohexyl phthalate
from: inks, toner, and colorants;
paints and coatings; adhesives and
sealants (e.g., paper products,
textiles, products using cellulose
film, etc.)
(Hvdro-Gard. 2024;
Hallstar. 2022: LANXESS.
2021: U.S. EPA. 2020c:
Earthiustice. 2019;
MEMA. 2019; U.S. EPA.
2019e; Gans Ink and
Supply. 2018; Hvdro-Gard.
2017a. b; U.S. CPSC.
2015)
Disposal
Disposal
Disposal
" Life Cycle Stage Use Definitions (40 CFR 711.3)
- "Industrial use" means use at a site at which one or more chemicals or mixtures are manufactured (including
imported) or processed.
- "Commercial use" means the use of a chemical or a mixture containing a chemical (including as part of an article) in a
commercial enterprise providing saleable goods or services.
- "Consumer use" means the use of a chemical or a mixture containing a chemical (including as part of an article, such
as furniture or clothing) when sold to or made available to consumers for their use.
- Although EPA has identified both industrial and commercial uses here for purposes of distinguishing scenarios in this
document, the Agency interprets the authority over "any manner or method of commercial use" under TSCA section
6(a)(5) to reach both.
h These categories of COUs appear in the LCD and broadly represent COUs of DCHP in industrial and/or commercial
settings.
c These subcategories reflect more specific COUs of DCHP.
J The consumer COU of "Toys, playground, and sporting equipment" was removed and not included in DCHP's final
scooins document. The U.S. CPSC Chronic Hazard Advisory Panel (CHAP) reoort from 2014 (U.S. CPSC. 2014) that
states, "DCHP is currently not found in children's toys or child care articles, and it is not widely found in the environment"
(page 117); the preamble of the 2017 CPSC final rule titled "Prohibition of Children's Toys and Child Care Articles
Containing Specified Phthalates," which explains that".. . the CPSC staff has not detected DCHP in toys and child care
articles durine routine compliance testins thus far.. ." (U.S. CPSC. 2017); As a result. EPA has no reasonably available
information demonstrating that the consumer use of DCHP in toys is intended, known, or reasonably foreseen, and has not
included it in the analysis for this draft risk evaluation of DCHP.
581 1.1.2.1 Conceptual Models
582 The conceptual model in Figure 1-4 presents the exposure pathways, exposure routes, and hazards to
583 human populations from industrial and commercial activities and uses of DCHP. There is potential for
584 exposure to workers and/or ONUs via inhalation and via dermal contact. The conceptual model also
585 includes potential ONU dermal exposure to DCHP in mists and dusts deposited on surfaces. EPA
586 evaluated activities resulting in exposures associated with distribution in commerce (e.g., loading,
587 unloading) throughout the various life cycle stages and COUs (e.g., manufacturing, processing,
588 industrial use, commercial use, and disposal).
589
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590 Figure 1-5 presents the conceptual model for consumer activities and uses, Figure 1-6 presents general
591 population exposure pathways and hazards for environmental releases and wastes, and Figure 1-7
592 presents the conceptual model for ecological exposures and hazards from environmental releases and
593 wastes.
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Industrial and Commercial Exposure Pathway Exposure Route Populations Hazards
Activities / Uses"
595 Figure 1-4. DCHP Conceptual Model for Industrial and Commercial Activities and Uses: Potential Exposure and Hazards
596 11 Some products are used in both commercial and consumer applications. See Table 1-1 for categories and subcategories of COUs.
597 h Fugitive air emissions are emissions that are not routed through a stack and include fugitive equipment leaks from valves, pump seals, flanges,
598 compressors, sampling connections and open-ended lines; evaporative losses from surface impoundment and spills; and releases from building ventilation
599 systems.
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CONSUMER ACTIVITIES/ EXPOSURE EXPOSURE POPULATIONS HAZARDS
XJSES PATHWAYS ROUTES EXPOSED
601 Figure 1-5. DC HP Conceptual Model for Consumer Activities and Uses: Potential Exposures and Hazards
602 The conceptual model presents the exposure pathways, exposure routes, and hazards to human populations from consumer activities and uses of DCHP.
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RELEASES AND WASTES FROM INDUSTRIAL / EXPOSITRF. PATHWAYS nintmr Dranrt POPULATIONS HAZARDS
COMMERCIAL ' CONSUMER USES EXPOSED1
604 Figure 1-6. DC HP Conceptual Model for Environmental Releases and Wastes: General Population Hazards
605 The conceptual model presents the exposure pathways, exposure routes, and hazards to human populations from releases and wastes from industrial,
606 commercial, and/or consumer uses of DCPIP.11 Industrial wastewater or liquid wastes may be treated on-site and then released to surface water (direct
607 discharge), or pre-treated and released to publicly owned treatment works (POTWs) (indirect discharge). For consumer uses, such wastes may be released
608 directly to POTW. Drinking water will undergo further treatment in drinking water treatment plant. Groundwater may also be a source of drinking water.
609 Inhalation from drinking water may occur via showering. b Populations assessed include PESS.
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RELEASES AND WASTES FROM INDUSTRIAL i
COMMERCIAL ICONSUMER USES
EXPOSURE PATHWAYS
POPULATIONS
EXPOSED
HAZARDS
611 Figure 1-7. DC HP Conceptual Model for Environmental Releases and Wastes: Ecological Exposures and Hazards
612 The conceptual model presents the exposure pathways, exposure routes, and hazards to human populations from releases and wastes from industrial,
613 commercial, and/or consumer uses of DCHP.11 Industrial wastewater or liquid wastes may be treated on-site and then released to surface water (direct
614 discharge), or pre-treated and released to POTWs (indirect discharge). For consumer uses, such wastes may be released directly to POTW. Drinking water
615 will undergo further treatment in drinking water treatment plant. Groundwater may also be a source of drinking water. Inhalation from drinking water may
616 occur via showering.
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620
621
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630
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635
636
637
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1.1.3 Populations and Durations of Exposure Assessed
Based on the conceptual models presented in Section 1.1.2.1, EPA evaluated risk to humans and the
environment. Environmental risks were evaluated for acute and chronic exposure scenarios for aquatic
and terrestrial species, as appropriate. Human health risks associated with exposure to DCHP were
evaluated for acute, intermediate, and chronic exposure scenarios, as applicable based on reasonably
available exposure and hazard data as well as the relevant populations for each. Human populations
assessed include the following:
• Workers, including average adults and women of reproductive age;
• ONUs, including average adults;
• Consumers, including infants (<1 year), toddlers (1-2 years), children (3-5 and 6-10 years),
young teens (11-15 years), teenagers (16-20 years), and adults (21+ years);
• Bystanders, including infants (<1 year), toddlers (1-2 years), and children (3-5 and 6-10 years),
young teens (11-15 years), teenagers (16-20 years), and adults (21+ years);
• General population, including infants (<1 year), toddlers (1-5 years), children (6-10 years),
youth (11-15 and 16-20 years), and adults (21+ years).
• The age groups for consumers, bystanders, and general population are different because each life
stage used unique exposure factors (e.g., mouthing, drinking water ingestion, fish consumption
rates). These exposure factors are provided in EPA's Exposure Factors Handbook: 2011 Edition
(U.S. EPA. 201 lbY
Consistent with its Draft Proposed Approach for Cumulative Risk Assessment (CRA) of High-Priority
Phthalates and a Manufacturer-Requested Phthalate under the Toxic Substances Control Act (U.S.
EPA. 2023c). EPA is focusing its relative potency factor (RPF) analysis and phthalate CRA on
populations most relevant to the common hazard endpoint (i.e., reduced fetal testicular testosterone)—
specifically women of reproductive age and male infants and male children. This approach emphasizes a
common health effect for sensitive subpopulations; however, additional health endpoints are identified
for broader populations and described in the individual non-cancer human health hazard assessments for
DCHP (U.S. EPA. 2024v). DEHP (U.S. EPA. 2024w\ DBP (U.S. EPA. 2024u\ BBP (U.S. EPA.
2024t), DffiP (U.S. EPA, 2024x), and DINP (U.S. EPA. 2025b). Additionally, EPA is focusing its RPF
and CRA on acute duration exposures. This is because—as described further in the Draft Technical
Support Document for the CRA of DEHP, DBP, BBP, DIBP, DCHP, and DINP under TSCA (U.S. EPA.
2024ah)—there is evidence that effects on the developing male reproductive system consistent with a
disruption of androgen action can result from a single exposure during the critical window of
development.
1.1.3.1 Potentially Exposed and Susceptible Subpopulations
TSCA section 6(b)(4)(A) requires that risk evaluations "determine whether a chemical substance
presents an unreasonable risk of injury to health or the environment, without consideration of costs or
other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible
subpopulation identified as relevant to the risk evaluation by the Administrator, under the conditions of
use." TSCA section 3(12) states that "the term 'potentially exposed or susceptible subpopulation'
[PESS] means a group of individuals within the general population identified by the Administrator who,
due to either greater susceptibility or greater exposure, may be at greater risk than the general population
of adverse health effects from exposure to a chemical substance or mixture, such as infants, children,
pregnant women, workers, or the elderly."
This draft risk evaluation considers PESS throughout the human health risk assessment (Section 4),
including throughout the exposure assessment, hazard identification, and dose-response analysis
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supporting this assessment. EPA incorporated the following PESS into its assessment—women of
reproductive age; pregnant women, infants, children and adolescents; people who frequently use
consumer products and/or articles containing high-concentrations of DCHP; people exposed to DCHP in
the workplace; and people who may be in proximity to releasing facilities, including fenceline
communities, and people whose diets include large amounts of fish (i.e., subsistence fisher and Tribal
populations). These subpopulations are PESS because some have greater exposure to DCHP per body
weight (e.g., infants, children, adolescents), while some experience aggregate or sentinel exposures.
EPA also evaluated non-attributable exposures and cumulative risk to phthalates (i.e., DEHP, DBP,
BBP, DIBP, and DINP) for the U.S. civilian population using NHANES biomonitoring data. This non-
attributable cumulative risk from exposure to DEHP, DBP, BBP, DIBP, and DINP was taken into
consideration as part of EPA's cumulative risk calculations for DCHP, presented below in Sections 4.4.4
and 4.4.5 and around exposures to DCHP from both occupational and consumer COUs/OES.
Section 4.3.5 summarizes how PESS were incorporated into the risk evaluation through consideration of
potentially increased exposures and/or potentially increased biological susceptibility and summarizes
additional sources of uncertainty related to consideration of PESS.
1.2 Organization of the Risk Evaluation
This draft risk evaluation for DCHP includes five additional major sections, and several appendices, as
listed below:
• Section 2 summarizes basic physical and chemical characteristics as well as the fate and
transport of DCHP.
• Section 3 includes an overview of releases and concentrations of DCHP in the environment.
• Section 4 presents the human health risk assessment, including the exposure, hazard, and risk
characterization based on the DCHP COUs. It includes a discussion of PESS based on both
greater exposure and/or susceptibility as well as a description of aggregate and sentinel
exposures. Section 4 also includes EPA's CRA of DCHP, DEHP, DBP, BBP, DIBP, and DINP.
• Section 5 provides a discussion and analysis of the environmental risk assessment, including the
environmental exposure, hazard, and risk characterization based on the COUs for DCHP. It also
discusses assumptions and uncertainties and how they impact EPA's overall confidence in risk
estimates.
• Section 6 presents EPA's proposed determination of whether the chemical presents an
unreasonable risk to human health or the environment as a whole chemical approach and under
the assessed COUs.
• Appendix A provides a list of key abbreviations and acronyms used throughout this draft risk
evaluation.
• Appendix B provides a brief summary of the federal, state, and international regulatory history of
DCHP.
• Appendix C incudes a list and citations for all TSDs and supplemental files included in the draft
risk evaluation for DCHP.
• Appendix D provides a summary of updates made to COUs for DCHP from the final scope
document to this draft risk evaluation.
• Appendix E provides descriptions of the DCHP COUs evaluated by EPA.
• Appendix F provides the draft occupational exposure value for DCHP that was derived by EPA.
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2 CHEMISTRY AND FATE AND TRANSPORT OF DCHP
Physical and chemical properties determine the behavior and characteristics of a chemical that inform its
COUs, environmental fate and transport, potential toxicity, exposure pathways, routes, and hazards.
Environmental fate and transport includes environmental partitioning, accumulation, degradation, and
transformation processes. Environmental transport is the movement of the chemical within and between
environmental media, such as air, water, soil, and sediment. Thus, understanding the environmental fate
of DCHP informs the specific exposure pathways, and potential human and environmental exposed
populations that EPA considered in this draft risk evaluation.
Sections 2.1 and 2.2 summarize the physical and chemical properties, and environmental fate and
transport of DCHP, respectively. EPA's Draft Physical Chemistry and Fate and Transport Assessment
for DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024z) provides further details.
2.1 Summary of Physical and Chemical Properties
EPA gathered and evaluated physical and chemical property data and information according to the
process described in the Draft Systematic Review Protocol for Dicyclohexyl Phthalate (DCHP) (U.S.
EPA. 2024ag). During the evaluation of DCHP, EPA considered both measured and estimated physical
and chemical property data/information summarized in Table 2-1, as applicable. Information on the full,
extracted data set is available in the Data Quality Evaluation and Data Extraction Information for
Physical and Chemical Properties for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024i).
Table 2-1. Physical and Chemical Properties of DCHP
Property
Selected Value
Reference
Overall
Quality Rating
Molecular Formula
C20H26O4
Molecular Weight
330.43 g/mol
Physical Form
Solid, prism
(Havnes, 2014)
High
Physical Properties
White granular solid
(NLM. 2024)
High
Melting Point
66 °C
(Havnes, 2014)
High
Boiling Point
225 °C at 4 mm Hg
(Havnes, 2014)
High
Density
1.383 g/cm3
(Havnes, 2014)
High
Vapor Pressure
8.69 xlO~7mmHg
(NLM. 2024)
High
Vapor Density
No data
Water Solubility
0.030-1.48 mg/Lt?
(U.S. EPA. 2017)
Medium
Octanol: Water Partition
coefficient (log KOW)
4.82
(EC/HC. 2017)
High
Octanol:Air Partition
10.23 a
(U.S. EPA. 2017)
Medium
Coefficient (log Koa)
Henry's Law Constant
9.446xl0~8 atnrmVmol at 25 °C a
(U.S. EPA. 2017)
Medium
Flash Point
207 °C
(RSC. 2019)
Medium
Auto-Flammability
No data
Viscosity
Solid, N/A
(NLM. 2024)
High
11 Modeled value using EPI Suite™
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2.2 Summary of Environmental Fate and Transport
Reasonably available environmental fate data—including biotic and abiotic biodegradation rates,
removal during wastewater treatment, volatilization from lakes and rivers, and organic carbon:water
partition coefficient (log Koc)—are the parameters used in this draft risk evaluation. In assessing the
environmental fate and transport of DCHP, EPA considered the full range of results from the available
data sources with medium and high data quality ratings collected through systematic review.
Information on the full extracted data set is available in the Data Quality Evaluation and Data
Extraction Information for Physical and Chemical Properties for Dicyclohexyl Phthalate (DCHP) (U.S.
EPA. 20240.
Other fate estimates were based on modeling results from EPI Suite™ (U.S. EPA. 20121 a predictive
tool for physical and chemical properties and environmental fate estimation.
EPA evaluated the reasonably available information to characterize the physical and chemical properties
and environmental fate and transport of DCHP. The key points are summarized below; DCHP
• Is a granular, crystalline solid under environmental conditions.
• Has a tendency to partition to soil, sediment, and particulate over water or air.
• Has limited solubility in water.
• Has low volatility in water or soil.
Given consistent results from numerous high-quality studies, there is robust evidence that when present
in the environment, DCHP
• May degrade through hydrolysis, photolysis, aerobic or anaerobic biodegradation.
• May transport through the air and be deposited to soil or water.
• Will sorb to particulate in the atmosphere and in water.
• Is expected to be removed in wastewater treatment processes by sorbing to particulate, biosolids,
and sludge.
As a result of limited studies identified, there is moderate confidence that DCHP
• Might be partially removed in conventional drinking water treatment.
• Might accumulate in individual fish and aquatic organisms, but is not expected to move up the
food chain in aquatic environments.
The following bullets summarize the key points of the partitioning analysis; DCHP
• Will remain mostly in water but may sorb to sediment when released to aquatic environments.
• Will sorb to atmospheric particulate but may end up in small amounts in soil, water, and
sediment when released to air.
• Will remain exclusively in soil when released to soil.
• Will sorb to particulate phases (soil, sediment, air particulate) with a small amount ending up in
water when released to all three phases (air, water, and soil).
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3 RELEASES AND CONCENTRATIONS OF DCHP IN THE
ENVIRONMENT
EPA estimated environmental releases and concentrations of DCHP. Section 3.1 describes the approach
and methodology for estimating releases, Section 3.2 presents environmental release estimates, and
Section 3.3 presents the approach and methodology for estimating environmental concentrations as well
as a summary of concentrations of DCHP in the environment.
3.1 Approach and Methodology
At the time of this draft risk evaluation, releases of DCHP have not been reported to programmatic
databases, including the Toxics Release Inventory (TRI), Discharge Monitoring Report (DMR), or
National Emissions Inventory (NEI). Therefore, EPA utilized models to estimate environmental releases
for each OES. This section provides an overview of the approach and methodology for assessing
releases to the environment from industrial, commercial, and consumer uses. Specifically, Sections 3.1.1
through 3.1.3 describe the approach and methodology for estimating releases to the environment from
industrial and commercial uses, and Section 3.1.4 describes the approach and methodology for assessing
down-the-drain releases from consumer uses.
3.1.1 Manufacturing, Processing, Industrial and Commercial Use
This subsection describes the grouping of manufacturing, processing, industrial and commercial COUs
into OESs, as well as the use of DCHP within each OES. Specifically, Section 3.1.1.1 provides a
crosswalk of COUs to OESs and Section 3.1.1.2 provides descriptions for the use of DCHP within each
OES.
3.1.1.1 Crosswalk of Conditions of Use to Occupational Exposure Scenarios
EPA categorized the COUs listed in Table 1-1 into OESs. Table 3-1 provides a crosswalk between the
COUs and OESs. Each OES is developed based on a set of occupational activities and conditions such
that similar occupational exposures and environmental releases are expected from the use(s) covered
under that OES. For each OES, EPA provided occupational exposure and environmental release results,
which are expected to be representative of the entire population of workers and sites for the given OES
in the United States. In some cases, EPA defined only a single OES for multiple COUs, while in other
cases the Agency developed multiple OESs for a single COU. EPA made this determination by
considering variability in release and use conditions and whether the variability required discrete
scenarios or could be captured as a distribution of exposures. The Draft Environmental Release and
Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q) provides
further information on specific OESs.
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Table 3-1. Crosswalk of Conditions of Use to Assessed Occupationa
Exposure Scenarios
Life Cycle
Stage
Category
Subcategory
OES
Manufacturing
Domestic manufacturing
Domestic manufacturing
Manufacturing
Importing
Importing
Import and repackaging
Repackaging
Repackaging (e.g., laboratory
chemicals)
Import and repackaging
Adhesive and sealant chemicals
Incorporation into adhesives and
in:
sealants
- Adhesive manufacturing
Plasticizer in:
- Adhesive manufacturing
- Paint and coating
Incorporation into adhesives and
sealants;
Processing
Processing -
incorporation into
formulation, mixture, or
reaction product
manufacturing
- Plastics product manufacturing
- Printing ink manufacturing
- Rubber product manufacturing
- Plastic material and resin
manufacturing
Incorporation into paints and
coatings;
PVC plastics compounding;
non-PVC material compounding
Stabilizing agent in:
- Plastics product manufacturing
- Paint and coating
manufacturing
- Asphalt paving, roofing, and
coating materials manufacturing
- Adhesive manufacturing
Incorporation into adhesives and
sealants;
Incorporation into paints and
coatings;
Incorporation into other
formulations, mixtures, or
reaction products;
PVC plastics compounding;
non-PVC material compounding
Processing -
incorporation into
article
Plasticizer in:
- Plastics product manufacturing
- Rubber product manufacturing
PVC plastics converting;
non-PVC material converting
Recycling
Recycling
Recycling
Distribution
Distribution in
commerce
Distribution in commerce
Distribution in commerce
Adhesives and sealants
Adhesives and sealants in:
- Transportation equipment
manufacturing
- Computer and electronic
product manufacturing
Application of adhesives and
sealants
Industrial Use
Finishing agent
Cellulose film production
Application of paints and
coatings
Inks, toner, and colorant
Inks, toner, and colorant
Application of paints and
products
products (e.g., screen printing
ink)
coatings
Paints and coatings
Paints and coatings
Application of paints and
coatings
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Life Cycle
Stage
Category
Subcategory
OES
Plastic and rubber
products not covered
elsewhere
Plastic and rubber products not
covered elsewhere in:
- Transportation equipment
manufacturing
Fabrication or use of final
products or articles
Adhesives and sealants
Adhesives and sealants
Application of adhesives and
sealants
Building/construction
materials not covered
elsewhere
Building/construction materials
not covered elsewhere
Fabrication or use of final
products or articles
Inks, toner, and colorant
products
Inks, toner, and colorant
products (e.g., screen printing
ink)
Application of paints and
coatings
Commercial Use
Laboratory chemical
Laboratory chemical
Use of laboratory chemicals
Paints and coatings
Paints and coatings
Application of paints and
coatings
Other articles with
routine direct contact
during normal use
including rubber
articles; plastic articles
(hard)
Other articles with routine
direct contact during normal use
including rubber articles; plastic
articles (hard)
Fabrication or use of final
products or articles
Disposal
Disposal
Disposal
Waste handling, treatment, and
disposal
798 3.1.1.2 Description of DCHP Use for Each OES
799 After EPA characterized the OESs for the occupational exposure assessment of DCHP, the occupational
800 uses of DCHP for all OESs were summarized. Brief summaries of the uses of DCHP for all OESs are
801 presented in Table 3-2.
802
803 Table 3-2. Description of the Use of DCHP for Each OES
OES
Use of DCHP
Manufacturing
DCHP is formed through the reaction of phthalic anhydride with
cyclohexane ring alcohols (cyclohexanol).
Import and repackaging
DCHP is imported domestically for use and/or may be repackaged before
shipment to formulation sites.
PVC plastics compounding
PVC plastics converting
DCHP is used as an additive in PVC plastics to increase flexibility.
Incorporation into adhesives and
sealants
DCHP is a plasticizer and stabilizing agent in adhesive and sealant products
for industrial and commercial use.
Incorporation into paints and
coatings
DCHP is a plasticizer and stabilizing agent in paint and coating products
for industrial and commercial use.
Incorporation into other
formulations, mixtures, or
reaction products, not covered
elsewhere
DCHP is incorporated into products, such as laboratory chemicals and
asphalt paving, roofing, and coating materials.
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OES
Use of DCHP
Non-PVC material compounding
Non-PVC material converting
DCHP is used as an additive in non-PVC polymers, such as rubber and
cellulose, to increase flexibility.
Application of adhesives and
sealants
Industrial and commercial sites often apply DCHP in powdered form to
serve as a hardener, thickener, or curing agent for adhesive and sealant
materials. Liquid adhesive and sealant products containing DCHP are
generally thick and paste-like, and these products are applied using roll or
bead application methods. Products may also be applied using a syringe or
caulk gun.
Application of paints and
coatings
Industrial and commercial sites apply DCHP-containing paints and coatings
using roll, brush, trowel, and spray application methods.
Use of laboratory chemicals
DCHP is a laboratory chemical used for laboratory analyses in solid and
liquid forms.
Recycling
A fraction of PVC plastics that contain DCHP are recycled either in-house
or at PVC recycling facilities for continuous compounding of new PVC
material.
Fabrication or use of final
products or articles
DCHP is found in a wide array of different final articles not found in other
OES such as wall coverings or other solid plastic or rubber products.
Waste handling, treatment, and
disposal
DCHP-containing products or residuals are managed as waste to be treated
and/or disposed.
804 3.1.2 Estimating the Number of Release Days per Year for Facilities in Each PES
805 Based on the limited data on the number of release days for the majority of the OESs, EPA developed
806 generic estimates of the number of annual operating days (days/year) for facilities in each OES, as
807 presented in Table 3-3. Generally, EPA does not have information on the number of operating days for
808 facilities; however, the Agency used Generic Scenarios (GSs) or Emission Scenario Documents (ESDs)
809 to assess the number of operating days for a given OES. EPA estimated average daily releases for
810 facilities by assuming that the number of release days is equal to the number of operating days.
811
Table 3-3. Generic Estimates of Number of
Operating Days per Year for Each OES
Occupational Exposure
Scenario
Operating
Days (days/yr)
Basis
Manufacturing
250
EPA assumed year-round site operation for 5 days each
week, considering a 2-week downtime, totaling 250
days/year.
Import and repackaging
208-260
The 2022 Chemical Repackaging GS estimated the total
number of operating days as one of three discrete values
based on the typical shift lengths of operators over the
course of a full year. Shift lengths include 8, 10, or 12
hour/day shifts, which resulted in operating day estimates of
174, 208, or 260 days/year. EPA assessed releases using
Monte Carlo modeling (see Draft Environmental Release
and Occupational Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024q)). which used a 50th to
95th percentile range of 208-260 davs/vear (U.S. EPA.
2022a).
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Occupational Exposure
Scenario
Operating
Days (days/yr)
Basis
Incorporation into adhesives
and sealants
250
EPA assumed year-round site operation for 5 days each
week, considering a 2-week downtime, totaling 250
days/year.
Incorporation into paints and
coatings
250
EPA assumed year-round site operation for 5 days each
week, considering a 2-week downtime, totaling 250
days/year.
Incorporation into other
formulations, mixtures, and
reaction products not covered
elsewhere
250
EPA assumed year-round site operation for 5 days each
week, considering a 2-week downtime, totaling 250
days/year.
PVC plastics compounding
223-254
The 2021 Revised Draft GS on the Use of Additives in
Plastic Compounding estimated the number of operating
days as 148-264 days/year. Release estimates that EPA
assessed using Monte Carlo modeling (see Draft
Environmental Release and Occupational Exposure
Assessment for DicvclohexvlPhthalate (DCHP) (U.S. EPA.
2024q)) used a 50th to 95th percentile ranse of 223-254
davs/vear (U.S. EPA. 2021d. 2014c).
PVC plastics converting
219-251
The 2021 Revised Draft GS on the Use of Additives in the
Thermoplastics Converting Industry estimated the number of
operating days as 138-253 days/year. Release estimates that
EPA assessed using Monte Carlo modeling (see Draft
Environmental Release and Occupational Exposure
Assessment for Dicvclohexvl Phthalate (DCHP) (U.S. EPA.
2024a)) used a 50th to 95th percentile ranee of 219-251
davs/vear (U.S. EPA. 2021e).
Non-PVC material
compounding
234-280
The 2021 Revised Draft GS on the Use of Additives in
Plastic Compounding and the 2020 SpERC Factsheet on
Rubber Production and Processing estimated the total
number of operating days as 148-300 days/year. Release
estimates that EPA assessed using Monte Carlo modeling
(see Draft Environmental Release and Occupational
Exposure Assessment for Dicvclohexvl Phthalate (DCHP)
(U.S. EPA. 2024q)) used a 50th to 95th percentile ranse of
234-280 davs/vear (U.S. EPA. 2021d: ESIG. 2020b: U.S.
EPA. 2014c)
Non-PVC material converting
219-251
The 2021 Revised Draft GS on the Use of Additives in the
Thermoplastics Converting Industry> estimated the number of
operating days as 137-254 days/year. Release estimates that
EPA assessed using Monte Carlo modeling (see Draft
Environmental Release and Occupational Exposure
Assessment for Dicvclohexvl Phthalate (DCHP) (U.S. EPA.
2024q)) used a 50th to 95th percentile ranse of 219-251
davs/vear (U.S. EPA. 2021e).
Application of adhesives and
sealants
232-325
Based on several end use products categories, the 2015 ESD
on the Use of Adhesives estimated the total number of
operating days as 50-365 days/year. Release estimates that
EPA assessed using Monte Carlo modeling (Draft
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Occupational Exposure
Scenario
Operating
Days (days/yr)
Basis
Environmental Release and Occupational Exposure
Assessment for DicvclohexvlPhthalate (DCHP) (U.S. EPA.
2024a)) used a 50th to 95th percentile ranee of 232-325
davs/vear (OECD. 2015b).
Application of paints and
coatings
257-287
EPA assessed the total number of operating days based on
the 2011 ESD on Radiation Curable Coatings, Inks and
Adhesives, the 2011 ESD on Coating Application via Spray-
Painting in the Automotive Finishing Industry, the 2004 GS
on Spray Coatings in the Furniture Industry, and the SpERC
Factsheet for Industrial Application of Coatings and Inks by
Spraying. These sources estimated the total number of
operating days as 225-300 days/year. Release estimates that
EPA assessed using Monte Carlo modeling (Draft
Environmental Release and Occupational Exposure
Assessment for Dicvclohexvl Phthalate (DCHP) (U.S. EPA.
2024a)) used a 50th to 95th percentile ranee of 257-287
davs/vear (ESIG. 2020a; OECD. 201 la. b; U.S. EPA.
2004c).
Use of laboratory chemicals
Solid and
Liquid: 235-
258
The 2023 Use of Laboratory Chemicals GS estimated the
total number of operating days with a discrete distribution
based on the shift lengths of operators over the course of a
full year. Shift lengths include 8, 10, or 12 hour/day shifts,
which result in a range of 174-260 days/year for operating
days. Release estimates that EPA assessed using Monte
Carlo modeling (Draft Environmental Release and
Occupational Exposure Assessment for Dicvclohexvl
Phthalate (DCHP) (U.S. EPA. 2024q)) used a 50th to 95th
percentile ranee of 235-258 davs/vear (U.S. EPA. 2023e).
Fabrication or use of final
products or articles
250
EPA assumed year-round site operation for 5 days each
week, considering a 2-week downtime, totaling 250
days/year. However, EPA was not able to perform a
quantitative release assessment for this OES because the
release parameters were unknown and unquantifiable.
Recycling
223-254
The 2021 Revised Draft GS on the Use of Additives in
Plastic Compounding estimated the number of operating
days as 148-264 days/year. Release estimates that EPA
assessed using Monte Carlo modeling (see Draft
Environmental Release and Occupational Exposure
Assessment for Dicvclohexvl Phthalate (DCHP) (U.S. EPA.
2024a)) used a 50th to 95th percentile ranee of 223-254
davs/vear (U.S. EPA. 2021d. 2014c).
Waste handling, treatment,
and disposal
250
EPA assumed year-round site operation for 5 days each
week, considering a 2-week downtime, totaling 250
days/year.
3.1.3 Daily Release Estimation
814 For each OES, EPA estimated releases to each medium of release using 2020 CDR data (U.S. EPA.
815 2020a). GSs and ESDs, and EPA published models as shown in Figure 3-1. Where available, EPA used
816 GSs or ESDs to estimate number of release days, which EPA used to convert between annual release
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estimates and daily release estimates. EPA used 2020 CDR, 2020 U.S. County Business Practices, and
Monte Carlo modeling data to estimate the number of sites using DCHP within an OES. Generally,
information for reporting sites in CDR was sufficient to accurately characterize each reporting site's
OES. The Draft Environmental Release and Occupational Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024q) describes EPA's approach and methodology for estimating daily
releases and provides detailed facility level results for each OES.
For each OES, EPA estimated DCHP releases per facility to each release medium applicable to that
OES. For DCHP, EPA assessed releases to water, air, or land (i.e., disposal to land).
Figure 3-1. An Overview of How EPA Estimated Daily Releases for Each OES
CDR = Chemical Data Reporting; ESD = Emission Scenario Document; GS =
Generic Scenario; SpERC = Specific Environmental Release Category
3.1.4 Consumer Down-the-Drain and Landfills
EPA evaluated down-the-drain releases of DCHP for consumer COUs qualitatively. Although the
Agency acknowledges that there may be DCHP releases to the environment via the cleaning and
disposal of adhesives and sealants, the Agency did not quantitatively assess down-the-drain and disposal
scenarios of consumer products due to limited information from monitoring data as well as limited
availability of modeling tools that can adequately quantify disposal. EPA provides a qualitative
assessment of down-the-drain releases of DCHP using physical and chemical properties in this section.
See EPA's Draft Consumer and Indoor Dust Exposure Assessment for Dicyclohexyl phthalate (DCHP)
(U.S. EPA. 2024c) for further details. For example, adhesives and sealants can be disposed down-the-
drain when people using them wash their hands, brushes, sponges, and other product-applying tools.
Very limited information is available on wastewater treatment and the removal of DCHP in drinking
water treatment plants. As stated in the Draft Physical Chemistry and Fate And Transport Assessment
for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024z). no data was identified by the EPA for DCHP in
drinking water. Based on the low water solubility and log Kow, DCHP in water is expected to mainly
partition to suspended solids present in water. The available information suggest that the use of
flocculants and filtering media could potentially help remove DCHP during drinking water treatment by
sorption into suspended organic matter, settling, and physical removal.
In addition, adhesives and sealant products can be disposed of when users no longer have use for them
or when the products have reached the product shelf life and are taken to landfills. All other solid
products and articles listed in Table 4-6 can be removed and disposed of in landfills, or other waste
handling locations that properly manage the disposal of products like adhesives and sealants. DCHP is
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expected to be persistent as it leaches from consumer products disposed of in landfills. Due to low water
solubility, DCHP is likely to be present in landfill leachate up to its aqueous limit of solubility (1.48
mg/L). However, due to its affinity for organic carbon, DCHP is expected to be immobile in
groundwater. Even in cases where landfill leachate containing DCHP were to migrate to groundwater,
DCHP would likely partition from groundwater to organic carbon present in the subsurface (U.S. EPA.
2024p).
3.2 Summary of Environmental Releases
3.2.1 Manufacturing, Processing, Industrial and Commercial
EPA combined its estimates for total production volume, release days, number of facilities, and hours of
release per day to estimate a range of daily releases for each OES. Table 3-4 presents a summary of
these ranges across facilities. See the Draft Environmental Release and Occupational Exposure
Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q) for additional detail on deriving the
overall confidence score for each OES. EPA was not able to estimate site-specific releases for the
fabrication or use of final products or articles OES. Disposal sites handling post-consumer, end-use
DCHP were not quantifiable due to the wide and disperse use of DCHP in PVC and other products. Pre-
consumer waste handling, treatment, and disposal are assumed to be captured in upstream OESs.
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869 Table 3-4. Summary of EPA's Daily Release Estimates for Each PES and EPA's Overall Confidence in these Estimates
OES
Estimated
Release aero
(kg/site-(
Daily
ss Sites
ay)
Type of
Discharge," Air
Emission,6 or
Transfer for
Disposal2
Estimated Release
Frequency across Sites
(days)"
Number of Facilities2
Weight of
Scientific
Evidence
Rating^
Sources
Central
Tendency
High-
End
Central
Tendency
High-
End
Manufacturing
9.4E-02
0.42
Stack Air
250
1 - LANXESS
Corporation,
Pittsburgh, PA
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
0.12
0.55
Fugitive Air, Water,
Incineration, or
Landfill
0.94
Water, Incineration,
or Landfill
0.15
0.57
Incineration or
Landfill
2.5
11
Stack Air
250
1 - Vertellus LLC,
Indianapolis, IN
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
3.2
15
Fugitive Air, Water,
Incineration, or
Landfill
12
Water, Incineration,
or Landfill
4.0
15
Incineration or
Landfill
Import and
repackaging
1.5
9.3
Stack Air
208
260
2 - United Initiators,
Inc., Elyria, OH;
Nouryon Chemicals
LLC, Chicago, IL
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
1.9
12
Fugitive Air, Water,
Incineration, or
Landfill
4.0
8.2
Water, Incineration,
or Landfill
2.4
13
Incineration or
Landfill
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OES
Estimated
Release aero
(kg/site-(
Daily
ss Sites
ay)
Type of
Discharge," Air
Emission,6 or
Transfer for
Disposal2
Estimated Release
Frequency across Sites
(days)"
Number of Facilities2
Weight of
Scientific
Evidence
Rating^
Sources
Central
Tendency
High-
End
Central High-
Tendency End
Incorporation into
adhesives and
sealants
0.11
0.70
Stack Air
250
5-9 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
0.14
0.93
Fugitive Air, Water,
Incineration, or
Landfill
2.6
4.9
Water, Incineration,
or Landfill
0.18
0.99
Incineration or
Landfill
Incorporation into
paints and
coatings
1.2E-02
0.10
Stack Air
250
20-34 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
1.6E-02
0.14
Fugitive Air, Water,
Incineration, or
Landfill
1.1
3.0
Water, Incineration,
or Landfill
2.0E-02
0.15
Incineration or
Landfill
Incorporation into
other
formulations,
mixtures, and
reaction products
8.3E-02
0.78
Stack Air
250
11-22 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
0.11
1.0
Fugitive Air, Water,
Incineration, or
Landfill
0.13
1.2
Water, Incineration,
or Landfill
0.13
1.2
Incineration or
Landfill
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OES
Estimated
Release aero
(kg/site-(
Daily
ss Sites
ay)
Type of
Discharge," Air
Emission,6 or
Transfer for
Disposal2
Estimated Release
Frequency across Sites
(days)"
Number of Facilities2
Weight of
Scientific
Evidence
Rating^
Sources
Central
Tendency
High-
End
Central
Tendency
High-
End
PVC plastics
compounding
0.12
4.1
Fugitive or Stack
Air
223
254
5-9 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
0.83
7.9
Fugitive Air, Water,
Incineration, or
Landfill
3.5
18
Water, Incineration,
or Landfill
1.1
6.1
Water
1.4
11
Incineration or
Landfill
PVC plastics
converting
7.2E-03
0.19
Fugitive or Stack
Air
219
251
42-67 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
4.7E-02
0.35
Fugitive Air, Water,
Incineration, or
Landfill
0.96
1.9
Water, Incineration,
or Landfill
0.13
0.41
Water
0.43
1.4
Incineration or
Landfill
Non-PVC
material
compounding
3.1E-02
0.88
Fugitive or Stack
Air
234
280
2-4 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
0.25
1.6
Fugitive Air, Water,
Incineration, or
Landfill
1.5
2.9
Water, Incineration,
or Landfill
0.30
0.90
Water
0.41
2.1
Incineration or
Landfill
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OES
Estimated
Release aero
(kg/site-(
Daily
ss Sites
ay)
Type of
Discharge," Air
Emission,6 or
Transfer for
Disposal2
Estimated Release
Frequency across Sites
(days)"
Number of Facilities2
Weight of
Scientific
Evidence
Rating^
Sources
Central
Tendency
High-
End
Central
Tendency
High-
End
Non-PVC
material
converting
2.0E-02
0.47
Fugitive or Stack
Air
219
251
2-4 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
0.13
0.86
Fugitive Air, Water,
Incineration, or
Landfill
1.1
2.9
Water, Incineration,
or Landfill
0.32
0.96
Water
1.1
3.3
Incineration or
Landfill
Application of
paints and
coatings
with overspray
controls
(no overspray
controls)
5.8E-09
[5.8E-09]
1.3E-08
[1.3E-
08]
Fugitive Air
257
287
1-14 generic sites
[1-14 generic sites]
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
1.4
[7.4E-02]
5.1
[0.63]
Stack Air
9.4E-02
[13]
0.82
[47]
Fugitive Air, Water,
Incineration, or
Landfill
1.3
[1.3]
3.3
[3.3]
Water, Incineration,
or Landfill
11
[0.12]
42
[0.88]
Incineration or
Landfill
Application of
adhesives and
sealants
5.7E-10
1.5E-09
Fugitive Air
232
325
6-80 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
4.2E-02
0.46
Stack Air
5.3E-02
0.61
Fugitive Air, Water,
Incineration, or
Landfill
0.33
1.6
Water, Incineration,
or Landfill
0.67
3.6
Incineration or
Landfill
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OES
Estimated
Release aero
(kg/site-(
Daily
ss Sites
ay)
Type of
Discharge," Air
Emission,6 or
Transfer for
Disposal2
Estimated Release
Frequency across Sites
(days)"
Number of Facilities2
Weight of
Scientific
Evidence
Rating^
Sources
Central
Tendency
High-
End
Central
Tendency
High-
End
Use of laboratory
chemicals - liquid
1.5E-12
2.6E-12
Fugitive or Stack
Air
235
258
36,873 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
4.0E-03
5.0E-03
Water, Incineration,
or Landfill
Use of laboratory
chemicals - solid
1.2E-04
1.0E-03
Stack Air
235
258
1,978-25,643 generic
sites
Moderate
2.3E-04
2.0E-03
Unknown Media
(Air, Water,
Incineration, or
Landfill)
6.6E-02
0.27
Water, Incineration,
or Landfill
3.1E-04
3.0E-03
Incineration or
Landfill
Recycling
7.4E-04
4.3E-03
Stack Air
223
254
58 generic sites
Moderate
CDR, Peer-
reviewed literature
(GS/ESD)
2.8E-03
9.2E-03
Fugitive Air, Water,
Incineration, or
Landfill
1.9E-03
3.9E-03
Water
1.3
1.8
Water, Incineration,
or Landfill
"Direct discharge to surface water; indirect discharge to non-POTWs; indirect discharge to POTWs
h Emissions via fugitive air or stack air, or treatment via incineration
c Transfer to surface impoundment, land application, or landfills
d Where available, EPA used industry provided information, ESDs, or GSs to estimate the number of release days for each COU.
'' Where available. EPA used 2020 CDR (U.S. EPA. 2020a). 2020 U.S. Countv Business Practices (U.S. Census Bureau. 2022). and Monte Carlo models to
estimate the number of sites that use DCHP for each COU.
' See Section 3.2.2 for details on EPA's determination of the weight of scientific evidence rating.
870
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873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
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3.2.2 Weight of Scientific Evidence Conclusions for Environmental Releases from
Industrial and Commercial Sources
For each OES, EPA considered the assessment approach, the quality of the data and models, and the
uncertainties in the assessment results to determine a level of confidence for the environmental release
estimates. Table 3-5 provides the Agency's weight of scientific evidence rating for each OES.
EPA integrated numerous evidence streams across systematic review sources to develop environmental
estimates for DCHP. The Agency made a judgment on the weight of scientific evidence supporting the
release estimates based on the strengths, limitations, and uncertainties associated with the release
estimates. EPA described this judgment using the following confidence descriptors: robust, moderate,
slight, or indeterminate.
In determining the strength of the overall weight of scientific evidence, EPA considered factors that
increase or decrease the strength of the evidence supporting the release estimate (whether measured or
estimated)—including quality of the data/information, relevance of the data to the release scenario
(including considerations of temporal and spatial relevance), and the use of surrogate data when
appropriate. In general, higher rated studies (as determined through data evaluation) increase the weight
of scientific evidence when compared to lower rated studies, and EPA gave preference to chemical- and
scenario-specific data over surrogate data (e.g., data from a similar chemical or scenario). For example,
a conclusion of moderate weight of scientific evidence is appropriate where there is measured release
data from a limited number of sources, such that there is a limited number of data points that may not
cover most or all the sites within the OES. A conclusion of slight weight of scientific evidence is
appropriate where there is limited information that does not sufficiently cover all sites within the COU,
and the assumptions and uncertainties are not fully known or documented. See EPA's Draft Systematic
Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances, Version 1.0: A Generic
TSCA Systematic Review Protocol with Chemical-Specific Methodologies (also called "Draft Systematic
Review Protocol") (U.S. EPA. 2021a) for additional information on weight of scientific evidence
conclusions.
Table 3-5 summarizes EPA's overall weight of scientific evidence conclusions for its release estimates
for each OES. In general, modeled data had data quality ratings of medium. As a result, for releases that
used GSs/ESDs, the weight of scientific evidence conclusion was moderate, when used in tandem with
Monte Carlo modeling.
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904 Table 3-5. Summary of Overall Confidence in Environmental Release Estimates by Occupational Exposure Scenario
OES
Weight of Scientific Evidence Conclusion in Release Estimates
Manufacturing
EPA found limited chemical specific data for the manufacturing OES and assessed environmental releases using models and model
parameters derived from CDR. the 2023 Methodology for Estimating Environmental Releases from Sampling Wastes (U.S. EPA.
2023e). and sources identified through svstematic review (including surrogates DINP and DIDP industrv-supplied data). EPA used
EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment, with media of release assessed using
assumptions from EPA/OPPT models and industry supplied data. EPA believes a strength of the Monte Carlo modeling approach is that
variation in model input values allows for estimation of a range of potential release values that are more likely to capture actual releases
than a discrete value. Additionally, Monte Carlo modeling uses a large number of data points (simulation runs) and considers the full
distributions of input parameters. EPA used facility-specific DCHP manufacturing volumes for all facilities that reported this
information to CDR and non-DCHP-specific operating parameters derived using data from a current U.S. manufacturing site for DIDP
and DINP that is assumed to operate using similar operating parameters as DCHP manufacturing. This information was used to provide
more accurate estimates than the generic values provided by the EPA/OPPT models. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of release estimates toward the true distribution of
potential releases. In addition, one DCHP manufacturing site claimed their DCHP production volume as CBI for the purpose of CDR
reporting; therefore, DCHP throughput estimates for this site are based on the site's reported export volume and their reported PV
percentage for industrial use. Additional limitations include uncertainties in the representativeness of the surrogate industry-provided
operating parameters from DIDP and DINP and the generic EPA/OPPT models for DCHP manufacturing sites. These limitations
decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases considering the strengths and limitations of the reasonably available data.
Import and
repackaging
EPA found limited chemical specific data for the import and repackaging OES and assessed releases to the environment using the
assumptions and values from the Chemical Repackaging Generic Scenario (U.S. EPA. 2022a). which the svstematic review process
rated high for data quality. EPA also referenced the 2023 Methodology for Estimating Environmental Releases from Sampling Wastes
(U.S. EPA. 2023e). EPA used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment. EPA
assessed the media of release using assumptions from the GS and EPA/OPPT models. EPA believes a strength of the Monte Carlo
modeling approach is that variation in model input values allows for estimation of a range of potential release values that are more
likely to capture actual releases than a discrete value. Additionally, Monte Carlo modeling uses a large number of data points
(simulation runs) and the full distributions of input parameters. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, because the default values in the GS are generic, there is
uncertainty in the representativeness of these generic site estimates in characterizing actual releases from real-world sites that import
and repackage DCHP. In addition, EPA lacks DCHP facility import volume data for all CDR-reporting import and repackaging sites
due to claims of CBI; therefore, throughput estimates for these sites are based on the CDR reporting threshold of 25,000 lb and an
annual DCHP national aggregate production volume range from CDR. These limitations decrease the weight of evidence.
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OES
Weight of Scientific Evidence Conclusion in Release Estimates
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Incorporation
into adhesives
and sealants
EPA found limited chemical specific data for the incorporation into adhesives and sealants OES and assessed releases to the
environment usina the ESD on the Formulation of Adhesives (OECD. 2009a). which has a hiah data qualitv rating based on the
systematic review process. EPA used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment
and assessed the media of release using assumptions from the ESD and EPA/OPPT models. EPA believes a strength of the Monte Carlo
modeling approach is that variation in model input values allows for estimation of a range of potential release values that are more
likely to capture actual releases than a discrete value. Monte Carlo modeling also considers a large number of data points (simulation
runs) and the full distributions of input parameters. Additionally, EPA used DCHP-specific data on concentrations in adhesive and
sealant products in the analysis to provide more accurate estimates than the generic values provided by the ESD. The safety and product
data sheets that EPA obtained these values from have high and medium data quality ratings based on the systematic review process.
These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the default values in the ESD may not be representative of actual
releases from real-world sites that incorporate DCHP into adhesives and sealants. In addition, EPA lacks data on DCHP-specific facility
production volume and number of formulation sites, which are needed to estimate site throughput of DCHP. EPA based throughput on
the CDR reporting threshold of 25,000 lb, an annual DCHP national aggregate production volume range, and ranges of downstream
sites. These limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Incorporation
into paints and
coatings
EPA found limited chemical specific data for the incorporation into paints and coatings OES and assessed releases to the environment
usina the Draft GS forthe Formulation ofWaterborne Coatinas (U.S. EPA. 2014a). which has amedium data qualitv ratina based on
systematic review. EPA used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment and
assessed the media of release using assumptions from the GS and EPA/OPPT models. EPA believes a strength of the Monte Carlo
modeling approach is that variation in model input values allows for estimation of a range of potential release values that are more
likely to capture actual releases than a discrete value. Monte Carlo modeling also considers a large number of data points (simulation
runs) and the full distributions of input parameters. Additionally, EPA used DCHP-specific data on concentrations in paint and coating
products to provide more accurate estimates of DCHP concentrations than the generic values provided by the GS. The safety and
product data sheets that EPA obtained these values from have medium to high data quality ratings based on the systematic review
process. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the generic default values in the GS are specific to waterborne
coatings and may not be representative of releases from real-world sites that incorporate DCHP into paints and coatings, particularly for
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OES
Weight of Scientific Evidence Conclusion in Release Estimates
sites formulating other coating types (e.g., solvent-borne coatings). In addition, EPA lacks data on DCHP-specific facility production
volume and number of formulation sites; therefore, EPA based throughput and production volume estimates on CDR which has a
reporting threshold of 25,000 lb, an annual DCHP production national aggregate production volume range, and ranges of downstream
sites. These limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Incorporation
into other
formulations,
mixtures, and
reaction
products
EPA found limited chemical specific data for the incorporation into other formulations, mixtures, and reaction products not covered
elsewhere OES and assessed releases to the environment usine the Draft GS for the Formulation of Waterborne Coatines (U.S. EPA.
2014a). which has a medium data aualitv ratine based on systematic review process. EPA used EPA/OPPT models combined with
Monte Carlo modeling to estimate releases to the environment, and media of release using assumptions from the GS and EPA/OPPT
models. EPA believes a strength of the Monte Carlo modeling approach is that variation in model input values allows for estimation of a
range of potential release values that are more likely to capture actual releases than a discrete value. Monte Carlo modeling also
considers a large number of data points (simulation runs) and the full distributions of input parameters. Additionally, EPA used DCHP-
specific data on concentrations in other formulation, mixture, and reaction products in the analysis to provide more accurate estimates
than the generic values provided by the GS. The safety and product data sheets that EPA obtained these values from have high and
medium data quality ratings based on the systematic review process. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the generic default values in the GS are based on the formulation
of paints and coatings and may not represent releases from real-world sites that incorporate DCHP into other formulations, mixtures, or
reaction products. In addition, because no entries in CDR indicated a use relevant to this formulation OES, and there were no other
sources to estimate the volume of DCHP used in this OES, EPA developed a high-end bounding estimate for production volume based
on the CDR reporting threshold of 25,000 lb or 5% of total product volume for a given use, which by definition is expected to over-
estimate the average release case. For DCHP facility throughputs, EPA used a range of generic default values in the GS. These
limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
PVC plastics
compounding
EPA found limited chemical specific data for the plastics compounding OES and assessed releases to the environment using the Revised
Draft GS for the Use of Additives in Plastic Compounding (U.S. EPA. 2021d). which has a medium data aualitv ratine based on
systematic review. EPA used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment, and
media of release using assumptions from the GS and EPA/OPPT models. EPA believes a strength of the Monte Carlo modeling
approach is that variation in model input values allows for estimation of a range of potential release values that are more likely to
capture actual releases than a discrete value. Monte Carlo modeling also considers a large number of data points (simulation runs) and
the full distributions of input parameters. These strengths increase the weight of evidence.
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OES
Weight of Scientific Evidence Conclusion in Release Estimates
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. The generic default concentration values in the GS consider all types of plastic
compounding and may not represent releases from real-world sites that compound DCHP into specific types of plastic raw material. In
addition, EPA lacks data on DCHP-specific facility production volume and number of compounding sites; therefore, EPA estimated
throughput and production volume based on CDR which has a reporting threshold of 25,000 lb and an annual DCHP production
national aggregate production volume range. These limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
PVC plastics
converting
EPA found limited chemical specific data for the plastics converting OES and assessed releases to the environment using the Revised
Draft GS on the Use of Additives in the Thermoplastics Converting Industry, which has a medium data quality rating based on
svstematic review (U.S. EPA. 2021e). EPA used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the
environment, and media of release using assumptions from the GS and EPA/OPPT models. EPA believes a strength of the Monte Carlo
modeling approach is that variation in model input values allows for estimation of a range of potential release values that are more
likely to capture actual releases than a discrete value. Monte Carlo also considers a large number of data points (simulation runs) and the
full distributions of input parameters. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the generic default values in the ESD are based on all types of
thermoplastics converting sites and processes and may not represent actual releases from real-world sites that convert DCHP-containing
raw material into plastic articles using a variety of methods, such as extrusion or calendering. In addition, EPA lacks data on DCHP-
specific facility production volume and number of converting sites; therefore, EPA estimated throughput based on CDR which has a
reporting threshold of 25,000 lb, an annual DCHP national aggregate production volume range, and ranges of downstream sites. These
limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Non-PVC
material
compounding
EPA found limited chemical specific data for the non-PVC material compounding OES and assessed releases to the environment using
the Revised Draft GS for the Use of Additives in Plastic Compounding and the ESD on Additives in the Rubber Industry (U.S. EPA.
202Id; OECD. 2004). Both sources have a medium data aualitv ratine based on the svstematic review process. EPA used EPA/OPPT
models combined with Monte Carlo modeling to estimate releases to the environment, and media of release using assumptions from the
GS, ESD, and EPA/OPPT models. EPA believes a strength of the Monte Carlo modeling approach is that variation in model input
values allows for estimation of a range of potential release values that are more likely to capture actual releases than a discrete value.
Monte Carlo modeling also considers a large number of data points (simulation runs) and the full distributions of input parameters.
These strengths increase the weight of evidence.
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OES
Weight of Scientific Evidence Conclusion in Release Estimates
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, there was a lack of concentration data for specific products that
contained DCHP; EPA relied on the GS and ESD to generate concentration estimates. These values may not be representative of actual
values from real-world sites that compound DCHP into non-PVC material. In addition, because no entries in CDR indicated a use
relevant to compounding or converting non-PVC material, and there were no other sources to estimate the volume of DCHP used in this
OES, EPA developed a high-end bounding estimate based on the CDR reporting threshold of 25,000 lb or 5% of total product volume
for a given use, which by definition is expected to over-estimate the average release case. These limitations decrease the weight of
evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Non-PVC
material
converting
EPA found limited chemical specific data for the non-PVC material converting OES and assessed releases to the environment using the
Revised Draft GS on the Use of Additives in the Thermoplastics Converting Industry and the ESD on Additives in the Rubber Industry
(U.S. EPA. 2021e; OECD. 2004). Both documents have a medium data aualitv ratine based on systematic review. EPA used
EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment, and media of release using
assumptions from the GS, ESD, and EPA/OPPT models. EPA believes a strength of the Monte Carlo modeling approach is that
variation in model input values allows for estimation of a range of potential release values that are more likely to capture actual releases
than a discrete value. Monte Carlo modeling also considers a large number of data points (simulation runs) and the full distributions of
input parameters. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, there was a lack of concentration data for specific products that
contained DCHP; EPA relied on the GS and ESD to generate concentration estimates. These values may not be representative of actual
values from real-world sites that convert DCHP into non-PVC articles. In addition, because no entries in CDR indicated a use relevant
to compounding or converting non-PVC material, and there were no other sources to estimate the volume of DCHP or number of sites
used in this OES, EPA developed a range of high-end bounding estimates based on the CDR reporting thresholds, or 25,000 lb of 5% of
total product volume for a given use, which by definition is expected to over-estimate the average release case. These limitations
decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Application of
adhesives and
sealants
EPA found limited chemical specific data for the application of adhesives and sealants OES and assessed releases to the environment
using the esd on the use of adhesives (OECD. 2015a). which has a medium data qualitv rating based on systematic review. EPA used
EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment, and media of release using
assumptions from the ESD and EPA/OPPT models. EPA believes a strength of the Monte Carlo modeling approach is that variation in
model input values allows for estimation of a range of potential release values that are more likely to capture actual releases than a
discrete value. Monte Carlo modeling also considers a large number of data points (simulation runs) and the full distributions of input
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OES
Weight of Scientific Evidence Conclusion in Release Estimates
parameters. Additionally, EPA used DCHP-specific data on concentration and application methods for different DCHP-containing
adhesives and sealant products in the analysis. These data provide more accurate estimates than the generic values provided by the ESD.
The safety and product data sheets from which these values were obtained have high and medium data quality ratings from the
systematic review process. These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the generic default values in the ESD may not represent releases
from real-world sites that incorporate DCHP into adhesives and sealants. The overall production volume of DCHP for this OES was
based on CDR data using the same assumptions as the Incorporation into adhesives and sealants OES. EPA lacks data on DCHP-
specific facility use volume and number of use sites; therefore, EPA based facility throughput estimates and number of sites on industry-
specific default facility throughputs from the ESD, DCHP product concentrations, and the overall production volume range from CDR
data which has a reporting threshold of 25,000 lb. EPA also had minimal data for solid additives in adhesives, and had to base the
DCHP concentration range for solid additives on the SDS for one product. These limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of reasonably available data.
Application of
paints and
coatings
EPA found limited chemical specific data for the application of paints and coatings OES and assessed releases to the environment using
the ESD on the Application of Radiation Curable Coatings, Inks and Adhesives and the GS on Coating Application via Spray Painting
in the Automotive Refinishina Industry (U.S. EPA. 2014b; OECD. 201 lb). These documents have a medium data qualitv rating based
on the systematic review process. EPA used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the
environment. EPA assessed media of release using assumptions from the ESD, GS, and EPA/OPPT models and a default assumption
that all paints and coatings are applied via spray application. EPA believes a strength of the Monte Carlo modeling approach is that
variation in model input values allows for estimation of a range of potential release values that are more likely to capture actual releases
than a discrete value. Monte Carlo modeling also considers a large number of data points (simulation runs) and the full distributions of
input parameters. Additionally, EPA used DCHP-specific data on concentration for different DCHP-containing paints and coatings in
the analysis. These data provide more accurate estimates than the generic values provided by the GS and ESD. The safety and product
data sheets that EPA obtained these values from have high and medium data quality ratings based on the systematic review process.
These strengths increase the weight of evidence.
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the generic default values in the GS and ESD may not represent
releases from real-world sites that incorporate DCHP into paints and coatings. Additionally, EPA assumes spray applications of the
coatings, which may not be representative of other coating application methods. In addition, EPA lacks data on DCHP-specific facility
use volume and number of use sites; therefore, EPA based throughput estimates on values from ESD, GS, and CDR data which has a
reporting threshold of 25,000 lb and an annual DCHP production volume range. EPA also lacked data for ready-to-apply coatings, and
consequently assumed a concentration range for liquid coatings based on the SDS for one product. These limitations decrease the
weight of evidence.
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Weight of Scientific Evidence Conclusion in Release Estimates
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of reasonably available data.
Use of
laboratory
chemicals
EPA found limited chemical specific data for the use of laboratory chemicals OES and assessed releases to the environment using the
Draft GS on the Use of Laboratory Chemicals (U.S. EPA. 2023a). which has a high data qualitv rating based on systematic review. EPA
used EPA/OPPT models combined with Monte Carlo modeling to estimate releases to the environment, and media of release using
assumptions from the GS and EPA/OPPT models for solid and liquid DCHP materials. EPA believes a strength of the Monte Carlo
modeling approach is that variation in model input values allows for estimation of a range of potential release values that are more
likely to capture actual releases than a discrete value. Monte Carlo modeling also considers a large number of data points (simulation
runs) and the full distributions of input parameters. EPA used SDSs from identified laboratory DCHP products to inform product
concentration and material states. These strengths increase the weight of evidence.
EPA believes the primary limitation to be the uncertainty in the representativeness of values toward the true distribution of potential
releases. In addition, EPA lacks data on DCHP-specific laboratory chemical throughput and number of laboratories; therefore, EPA
based the number of laboratories and throughput estimates on stock solution throughputs from the GS on the Use of Laboratory
Chemicals (U.S. EPA, 2023c) and on CDR reporting thresholds. Additionally, because no entries in CDR indicate a laboratory use and
there were no other sources to estimate the volume of DCHP used in this OES, EPA developed a high-end bounding estimate based on
the CDR reporting threshold of 25,000 lb or 5% of total product volume for a given use, which by definition is expected to over-
estimate the average release case. These limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of reasonably available data.
Fabrication or
use of final
products or
articles
No data were available to estimate releases for this OES and there were no suitable surrogate release data or models. This release is
described qualitatively.
Recycling
EPA found limited chemical specific data for the recycling OES. EPA assessed releases to the environment from recycling activities
using the Revised Draft GS for the Use of Additives in Plastic Compounding (U.S. EPA. 2021d) as surrogate for the recvcling process.
The GS has a medium data quality rating based on systematic review. EPA/OPPT models were combined with Monte Carlo modeling to
estimate releases to the environment. EPA believes the strength of the Monte Carlo modeling approach is that variation in model input
values and a range of potential release values are more likely to capture actual releases than discrete values. Monte Carlo modeling also
considers a large number of data points (simulation runs) and the full distributions of input parameters. EPA referenced the
Quantification and Evaluation of Plastic Waste in the United States, which has a medium quality rating based on systematic review
(Milbrandt et al.. 2022). to estimate the rate of PVC recvcling in the United States. EPA estimated the DCHP PVC market share (based
on the surrogate market shares from DINP and DIDP) to define an approximate recycling volume of PVC containing DCHP. These
strengths increase the weight of evidence.
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OES
Weight of Scientific Evidence Conclusion in Release Estimates
The primary limitation of EPA's approach is the uncertainty in the representativeness of estimated release values toward the true
distribution of potential releases at all sites in this OES. Specifically, the generic default values and release points in the GS represent all
types of plastic compounding sites and may not represent sites that recycle PVC products containing DCHP. In addition, EPA lacks
DCHP-specific PVC recycling rates and facility production volume data; therefore, EPA based throughput estimates on PVC plastics
compounding data and U.S. PVC recycling rates, which are not specific to DCHP, and may not accurately reflect current U.S. recycling
volume. DCHP may also be present in non-PVC plastics that are recycled; however, EPA was unable to identify information on these
recycling practices. These limitations decrease the weight of evidence.
Based on this information, EPA concluded that the weight of scientific evidence for this assessment is moderate, and the assessment
provides a plausible estimate of releases, considering the strengths and limitations of the reasonably available data.
Waste
handling,
treatment, and
disposal
No data were available to estimate releases for this OES and there were no suitable surrogate release data or models. This release is
described qualitatively.
Distribution in
commerce
These releases are assessed as part of individual OESs where the relevant activities occur.
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3.2.3 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the
Environmental Release Assessment
Manufacturers and importers of DCHP submit CDR data to EPA if they meet reporting threshold
requirements. Sites are only required to load production data into CDR if their yearly production volume
exceeds 25,000 lb. Sites can claim their production volume as CBI, further limiting the production
volume information in CDR. As a result, some sites that produce or use DCHP may not be included in
the CDR data set and the total production volume for a given OES may be under or overestimated. The
extent to which sites that are not captured in the CDR reports release DCHP into the environment is
unknown. The media of release for these sites is also unknown.
CDR information on the downstream use of DCHP at facilities is also limited; therefore, there is some
uncertainty as to the production volume attributed to a given OES. For OES with limited CDR data,
EPA developed potential production volume ranges given reported CDR data, known reporting
thresholds, and the national aggregate production volume of 500,000 to less than 1,000,000 lb for DCHP
in 2019. The Agency used the potential production volume ranges as uniform distributions in Monte
Carlo modeling when assessing releases for each OES. Due to the wide range of potential production
volumes attributable to certain OES, the overall releases may be over or underestimated. DCHP releases
at each site may vary from day to day, such that on any given day the actual daily release rate may be
higher or lower than the estimated average daily release rate.
The EPA has further identified the following additional uncertainties that contribute to the overall
uncertainty in the environmental release assessment:
• Use of Census Bureau data for Number of Facilities - In some cases, EPA determined the
maximum number of facilities for a given OES (for use in Monte Carlo modeling) from industry
data from the U.S. Census Bureau, County and Business Patterns data set (U.S. Census Bureau.
2022).
• Uncertainties Associated with Facility Throughputs - EPA estimated facility throughputs of
DCHP or DCHP-containing products using various methods, including using generic industry
data presented in the relevant GS or ESD, or by calculation based on estimated number of
facilities and overall production volume of DCHP from CDR for the given OES. In either case,
the values used for facility throughputs may encompass a wide range of possible values. Due to
these uncertainties, the facility throughputs may be under or overestimated.
• Uncertainties Associated with Number of Release Days - For most OESs, EPA estimated the
number of release days using data from GSs, ESDs, or SpERC factsheets. In such cases, EPA
used applicable sources to estimate a range of release days over the course of an operating year.
Due to uncertainty in DCHP-specific facility operations, release days may be under or
overestimated.
• Uncertainties Associated with DCHP-Containing Product Concentrations - In most cases,
the number of identified products for a given OES were limited. In such cases, EPA estimated a
range of possible DCHP concentrations for products in the OES. However, the extent to which
these products represent all DCHP-containing products within the OES is uncertain. For OESs
with little-to-no product data, EPA estimated DCHP concentrations from GSs or ESDs. Due to
these uncertainties, the average product concentrations may be under or overestimated.
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3.3 Summary of Concentrations of DCHP in the Environment
Based off the environmental release assessment summarized in Section 3.2 and detailed in EPA's Draft
Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP)
(U.S. EPA. 2024q). DCHP is expected to be released to the environment via air, water, biosolids, and
disposal to landfills. Environmental media concentrations were quantified in ambient air, sediment, and
surface water. Additional analysis of surface water used as drinking water was conducted for the Human
Health Risk Assessment (see Section 4.1.3). EPA relied on its fate assessment to determine which
environmental pathways to consider for its screening level analysis of environmental exposure and
general population exposure to environmental releases. Details on the environmental partitioning and
media assessment can be found in Draft Physical Chemistry and Fate and Transport Assessment for
Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024z). Briefly, based on DCHP's fate parameters (e.g.,
Henry's Law constant, log Koc, water solubility, fugacity modeling), EPA anticipated DCHP to be
predominantly in water, soil, and sediment. Soil concentration of DCHP from land applications were not
quantitatively assessed in the screening level analysis as DCHP was expected to have limited persistence
potential and mobility in soils receiving biosolids.
Further detail on the screening-level assessment of each environmental pathway can be found in EPA's
Draft Environmental Media, General Population, and Environmental Exposure Assessment for
Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024p). Because of limited environmental monitoring data
and lack of location data for DCHP releases, EPA began its environmental and general population
exposure assessment with a screening-level approach using the highest modeled environmental media
concentrations for the environmental pathways expected to be of greatest concern. The highest
environmental media concentrations were estimated using the release estimates for an OES associated
with a COU that, paired with conservative assumption of environmental conditions, resulted in the
greatest modeled concentration of DCHP in a given environmental medium type. Therefore, EPA did
not estimate environmental concentrations of DCHP resulting from all OES presented in Table 3-1.
The OES resulting in the highest environmental concentration of DCHP varied by environmental media
as shown in Table 3-6. PVC plastics compounding with or without consideration of wastewater
treatment efficiency yielded the highest water concentrations using a 7Q10 flow,1 30Q5 flow,2 and
harmonic mean.3 The Application of paints, coatings, adhesives, and sealants OES yielded the highest
ambient air concentration. The summary table also indicates whether the high-end estimate was used for
environmental or general population exposure assessment. For the screening-level analysis, if the high-
end environmental media concentrations did not result in potential environmental or human health risk,
no further OESs were assessed and no further refinements were pursued. For the surface water and
ambient air pathways, only the OESs resulting in the highest estimated water column or ambient air
concentrations were carried forward to the human health risk assessment (i.e., Plastic compounding for
water and Application of paints, coatings, adhesives, and sealants for ambient air).
1 7Q10 is defined as 7 consecutive days of lowest flow over a 10-year period. These flows are used to calculate estimates of
chronic surface water concentrations to compare with the COCs for aquatic life (Versar. 2014).
2 30Q5 is defined as 30 consecutive days of lowest flow over a 5-year period. These flows are used to determine acute human
exposures via drinking water (Versar. 2014).
3 Harmonic mean is defined as the inverse mean of reciprocal daily arithmetic mean flow values. These flows represent a
long-term average and are used to generate estimates of chronic human exposures via drinking water and fish ingestion.
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Table 3-6. Summary of High-End DCHP Concentrations in Various Environmental Media from
Environmental Re
eases
OES7
Release
Media
Environmental Media
DCHP
Concentration
Environmental or
General Population
PVC plastics
compounding
without wastewater
treatment
Water
Total water column (7Q10.''
median flow)
165 |ig/L
Environmental
Total water column (7Q10, p75
flow)
5.56 (ig/L
Environmental
Total water column (7Q10, p90
flow)
0.57 ng/L
Environmental
Median 7Q10 (benthic pore
water)
95.3 ng/L
Not carried forward to
environmental risk
assessment6
Median 7Q10 (benthic
sediment)
112,000 ng/kg
Not carried forward to
environmental risk
assessment6
PVC plastics
compounding
without wastewater
treatment
Water
Surface water (3 0Q5,'# median
flow)
126 |ig/L
General population
Surface water (harmonic mean,6
median flow)
87.7 ng/L
General Population
PVC plastics
compounding
with wastewater
treatment
Water
Surface water (30Q5, median
flow)
39.6 ng/L
General population
Surface water (harmonic mean,
median flow)
27.5 ng/L
General population
Application of
paints, and coatings
Fugitive air
Daily-averaged total (fugitive
and stack, 100 m)
67.57 (ig/m3
General population
Annual-averaged total (fugitive
and stack, 100 m)
46.28 (ig/m3
General population
"Table 3-1 provides the crosswalk of OES to COUs.
h 7Q10 is the 7 consecutive days of lowest flow over a 10-year period.
c See Section 4.4 for further details.
1#30Q5 is defined as 30 consecutive days of lowest flow over a 5-year period
" Harmonic mean is defined as the inverse mean of reciprocal daily arithmetic mean flow values. These flows
represent a long-term average.
3.3.1 Weight of Scientific Evidence Conclusions
Detailed discussion of the strengths, limitations, and sources of uncertainty for modeled environmental
media concentration leading to a weight of scientific evidence conclusion can be found in EPA's Draft
Environmental Media, General Population, and Environmental Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024pV However, the weight of scientific evidence conclusion is
summarized below for the modeled DCHP concentrations in surface water, sediment, and ambient air.
3.3.1.1 Surface Water
Due to the lack of release data for facilities discharging DCHP to surface water, releases to water were
modeled as described in Section 3.2. The high-end estimate of releases to water for each COU was
applied for surface water modeling as part of a conservative screening-level assessment. Additionally,
due to a lack of site-specific release information, a generic distribution of hydrologic flows was
developed from facilities which had been classified under relevant North American Industry
Classification System (NAICS) codes, and which had National Pollutant Discharge Elimination System
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(NPDES) permits. The flow rates were selected from the generated distributions and coupled with high-
end (95th percentile) release scenarios. EPA assumed higher releases are generally correlated with
higher receiving water body flows. EPA generally has moderate confidence in the modeled
concentrations as being representative of actual releases, with greater confidence in the modeled
scenarios where high-end release amounts are paired with high-end flow rates. Additionally, EPA has
robust confidence that no surface water release scenarios exceed the high-end concentrations presented
in this evaluation, which have been applied as screening values. Other model inputs were derived from
reasonably available literature collected and evaluated through EPA's systematic review process for
TSCA risk evaluations. All monitoring and experimental data included in this analysis were from
articles rated "medium" or "high" quality from this process.
The high-end modeled concentrations in the surface water and sediment identified through systematic
review exceeded the highest values available from monitoring studies by more than three orders of
magnitude. This confirms EPA's expectation that modeled concentrations presented here are biased
toward overestimation, and thus appropriate to be applied as a screening-level evaluation in the
environmental and general population exposure to environmental releases assessment.
3.3.1.2 Ambient Air
Similar to the surface water analysis, due to the lack of release data, releases to ambient air were
modeled using generic scenarios, and the high-end estimates of releases to ambient air for each COU
were applied for ambient air modeling. The uncertainties associated with the release data are detailed in
the Draft Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024q). However, EPA has robust confidence in using the IIOAC (Integrated
Indoor-Outdoor Air Calculator) modeling in the ambient air exposure assessment because its approach
and methodology were derived from peer-reviewed models and incorporate extensive feedback received
from the Science Advisory Committee on Chemicals. Due to the conservative assumptions made with
the use of high-end estimates, EPA has robust confidence that its modeled releases used for estimating
ambient air concentrations are appropriately conservative for a screening-level analysis.
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1030 4 HUMAN HEALTH RISK ASSESSMENT
DCHP - Human Health Risk Assessment (Section 4):
Key Points
EPA evaluated all reasonably available information to support human health risk characterization of DCHP for
workers, ONUs, consumers, bystanders, and the general population, including PESS. Exposures to workers,
ONUs, consumers, bystanders, and the general population are described in Section 4.1. Human health hazards
are described in Section 4.2. Human health risk characterization is described in Section 4.3.
Exposure Key Points
• EPA assessed inhalation and dermal exposures for workers and ONUs, as appropriate, for each OES
(Section 4.1.1). The primary route of exposure was inhalation.
• EPA assessed inhalation, dermal, and oral exposures for consumers and bystanders, as appropriate, for
each TSCA COU (Section 4.1.2) in scenarios that represent a range of use patterns and behaviors. The
primary route of exposure was dermal for most products, followed by inhalation.
• EPA assessed inhalation, oral, and dermal exposures for the general population via ambient air, surface
water, drinking water, and fish ingestion for Tribal populations and determined that all exposures
assessed for the general population were not of concern (Sections 4.1.3 and 4.3.4).
• EPA assessed non-attributable cumulative exposure to DEHP, DBP, BBP, DIBP, and DINP for the U.S.
civilian population using NHANES urinary biomonitoring data and reverse dosimetry (Section 4.4.2).
Hazard Key Points
• EPA identified effects on the developing male reproductive system consistent with a disruption of
androgen action, leading to phthalate syndrome, as the most sensitive and robust non-cancer hazard
associated with oral exposure to DCHP in experimental animal models (Section 4.2).
• A non-cancer POD of 2.4 mg/kg-day was selected to characterize non-cancer risks for acute,
intermediate, and chronic durations of exposure. A total uncertainty factor of 30 was selected for use as
the benchmark margin of exposure.
• EPA derived draft relative potency factors (RPFs) based on a common hazard endpoint (i.e., reduced
fetal testicular testosterone). Draft RPFs were derived via meta-analysis and benchmark dose (BMD)
modeling (Section 4.4.1). Given its limited toxicological data set, scaling by the RPF and application of
the index chemical POD provides a more sensitive and robust dose-response assessment than the
DCHP-specific POD.
Risk Assessment Key Points
• Dermal and ingestion exposures were not a risk driver for any duration of exposure or population.
• Inhalation exposures drive acute non-cancer risks to workers in occupational settings (Section 4.3.2).
• No potential non-cancer risk was identified for consumers (Section 4.3.3).
• No potential non-cancer risk was identified for the general population.
• EPA considered combined exposure across all routes of exposure for each individual occupational and
consumer COU to calculate aggregate risks (Sections 4.3.2 and 4.3.3). No potential aggregate risk was
identified for consumer COUs.
• EPA considered cumulative risk to workers and consumers through exposure to DCHP from
individual COUs in combination with cumulative non-attributable national exposure to DEHP, DBP,
BBP, DIBP, and DINP as estimated from NHANES biomonitoring data (Sections 4.4.4 and 4.4.5).
• EPA considered PESS throughout the exposure assessment, hazard identification, and dose-response
analysis supporting this draft risk evaluation (Section 4.3.5).
1031 4.1 Summary of Human Exposures
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4.1.1 Occupational Exposures
The following subsections briefly describe EPA's approach to assessing occupational exposures and
provide exposure assessment results for each OES. As stated in the final scope document (U.S. EPA.
2020b). the Agency evaluated exposures to workers and ONUs via the inhalation route—including
incidental ingestion of inhaled dust and exposures to workers via the dermal route from direct contact
with DCHP. Also, EPA accounted for dermal exposure to workers and ONUs from mist and dust
deposited on surfaces. The Draft Environmental Release and Occupational Exposure Assessment for
DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024ci) provides additional details on the development of
approaches and the exposure assessment results.
4.1.1.1 Approach and Methodology
As described in the final scope document for DCHP (U.S. EPA, 2020b), EPA distinguished exposure
levels among potentially exposed employees for workers and ONUs. In general, the primary difference
between workers and ONUs is that workers may handle DCHP and have direct contact with DCHP,
while ONUs work in the general vicinity of DCHP but do not handle DCHP. Where possible, for each
COU, EPA identified job types and categories for workers and ONUs.
As discussed in Section 3.1.1.1, EPA established OESs to assess the exposure scenarios within each
COU. Table 3-1 provides a crosswalk between COUs and OESs. EPA did not identify relevant
chemical-specific inhalation exposure monitoring data for the OESs. In the absence of inhalation
monitoring data, EPA used inhalation exposure models to estimate both central tendency and high-end
exposures. For inhalation exposure to dust in occupational settings, EPA used the data and approaches
from the Generic Model for Central Tendency and High-End Inhalation Exposure to Total and
Respirable Particulates Not Otherwise Regulated (PNOR) (U.S. EPA. 2021b). In all cases of
occupational dermal exposure to DCHP, EPA used a flux-limited dermal absorption model to estimate
high-end and central tendency dermal exposures for workers in each OES, as described in the Draft
Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP)
(U.S. EPA. 2024a).
EPA evaluated the quality of the models and data sources using the data quality review evaluation
metrics and the rating criteria described in the Draft Systematic Review Protocol (U.S. EPA. 2021a).
The Agency assigned an overall quality level of high, medium, or low to the relevant data. In addition,
EPA established an overall confidence level for the data when integrated into the occupational exposure
assessment. The Agency considered the assessment approach, the quality of the data and models, and
uncertainties in assessment results to assign an overall weight of scientific evidence rating of robust,
moderate, or slight.
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Figure 4-1. Approaches Used for Each Component of the Occupational Assessment for Each OES
CDR = Chemical Data Reporting; GS = Generic Scenario; ESD = Emission Scenario Document; BLS = Bureau
of Labor Statistics; PNOR = Particulates not Otherwise Regulated.
For inhalation and dermal exposure routes, EPA provides occupational exposure results representative
of both central tendency and high-end exposure conditions. The central tendency is expected to
represent occupational exposures in the center of the distribution for a given COU. For this risk
evaluation, EPA used the 50th percentile (median), mean (arithmetic or geometric), mode, or midpoint
value of a distribution to represent the central tendency scenario. Although the Agency preferred to
report the 50th percentile of the distribution, if the full distribution was unknown, EPA used either the
mean, mode, or midpoint of the distribution to represent the central tendency depending on the statistics
available for the distribution. The high-end exposure is expected to represent occupational exposures
that occur at probabilities above the 90th percentile, but below the highest exposure for any individual
(U.S. EPA. 1992). For this draft risk evaluation, EPA reported high-end results at the 95th percentile. If
the 95th percentile was not reasonably available, the Agency used a different percentile greater than or
equal to the 90th percentile but less than or equal to the 99th percentile—depending on the data that was
available for the distribution. If the full distribution is not known and the preferred statistics were not
reasonably available, EPA estimated a maximum or bounding estimate in lieu of the high-end. Table 4-1
provides a summary of the approach used to assess worker and ONU exposures and the Agency's
weight of scientific evidence rating for the given exposure assessments.
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Table 4-1. Summary of Exposure Monitoring and Modeling Data for Occupational Exposure Scenarios
OES
Inhalation Exposure
Dermal Exposure
Monitoring
Modeling
Weight of Scientific
Evidence Conclusion
Modeling
Weight of Scientific
Evidence Conclusion
Worker
# Data
Points
ONU
# Data
Points
Data
Quality
Ratings
Worker
ONU
Worker
ONU
Worker
ONU
Worker
ONU
Manufacturing
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
~
Moderate
Moderate
Import and
repackaging
X
N/A
X
N/A
N/A
V
V
Moderate
Moderate
~
Moderate
Moderate
Incorporation into
adhesives and
sealants
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
~
Moderate
Moderate
Incorporation into
paints and
coatings
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
V
Moderate
Moderate
Incorporation into
other
formulations,
mixtures, and
reaction products
not covered
elsewhere
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
V
Moderate
Moderate
PVC plastics
compounding
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
V
Moderate
Moderate
PVC plastics
converting
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
s
Moderate
Moderate
Non-PVC material
compounding
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
V
Moderate
Moderate
Non-PVC material
converting
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
s
Moderate
Moderate
Application of
adhesives and
sealants
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
s
Moderate
Moderate
Application of
paints and
coatings
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
V
Moderate
Moderate
Use of laboratory
chemicals
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
s
Moderate
Moderate
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OES
Inhalation Exposure
Dermal Exposure
Monitoring
Modeling
Weight of Scientific
Evidence Conclusion
Modeling
Weight of Scientific
Evidence Conclusion
Worker
# Data
Points
ONU
# Data
Points
Data
Quality
Ratings
Worker
ONU
Worker
ONU
Worker
ONU
Worker
ONU
Fabrication or use
of final products
or articles
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
~
Moderate
Moderate
Recycling
X
N/A
X
N/A
N/A
V
V
Moderate
Moderate
~
Moderate
Moderate
Waste handling,
treatment, and
disposal
X
N/A
X
N/A
N/A
~
~
Moderate
Moderate
~
~
Moderate
Moderate
Distribution in
Commerce"
X
N/A
X
N/A
N/A
X
X
N/A
N/A
X
X
N/A
N/A
" Activities related to distribution (e.g., loading, unloading) are considered throughout the DCHP life cycle, as well as qualitatively through a single distribution scenario.
1091
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4.1.1.2 Summary of Number of Workers and ONUs
The Draft Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024q) provides a summary of the estimates of the number of exposed workers and
ONUs for each OES. To prepare these estimates, EPA first identified relevant NAICS Codes for each
OES. For these NAICS codes, the Standard Occupational Classification (SOC) codes from the Bureau of
Labor Statistics (BLS) were used to classify SOC codes as either workers or ONUs. The Agency
assumed that all other SOC codes represent occupations where exposure is unlikely. EPA also estimated
the total number of facilities associated with the relevant NAICS Codes based on data from the U.S.
Census Bureau. To estimate the average number of potentially exposed workers and ONUs per site, the
total number of workers and ONUs were divided by the total number of facilities. The Draft
Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP)
(U.S. EPA. 2024q) provides additional details on the approach and methodology for estimating the
number of facilities using DCHP as well as the number of potentially exposed workers and ONUs.
Table 4-2 summarizes the number of facilities and total number of exposed workers for all OESs. For
scenarios in which the results are expressed as a range, the low end of the range is based on the 50th
percentile estimate of the number of sites and the upper end of the range is based on the 95th percentile
estimate of the number of sites.
Table 4-2. Summary of Total Number of Workers and ONUs Potentially Exposed to DCHP for
Each OES
OES
Total Exposed
Workers ab
Total Exposed
ONUs ttb
Number of
Facilities ab
Notes
Manufacturing
77
36
2
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015).
Import and
repackaging
40
18
2
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaged for two NAICS
codes identified.
Incorporation into
adhesives and sealants
90-162
35-126
5-9
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015).
Incorporation into paints
and coatings
280-476
70-170
20-34
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015).
Incorporation into other
formulations, mixtures,
and reaction products
not covered elsewhere
561-1,122
264-528
11-21
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
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OES
Total Exposed
Workers ab
Total Exposed
ONUs ttb
Number of
Facilities ab
Notes
15). Averaged for two NAICS
codes identified.
PVC plastics
compounding
135-243
60-108
5-9
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015).
PVC plastics converting
756-1,206
210-335
42-67
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015).
Non-PVC material
compounding
46-92
12-24
2-4
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaaed for three NAICS
codes identified.
Non-PVC material
converting
46-92
12-24
2-4
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaaed for three NAICS
codes identified.
Application of
adhesives and sealants
336-4,480
108-1,440
6-80
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaaed for 18 NAICS
codes identified.
Application of paints
and coatings
12-168
6-84
1-14
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaaed for 10 NAICS
codes identified.
Use of laboratory
chemicals
(liquid)
36,873
331,857
36,873
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaaed for two NAICS
codes identified.
Use of laboratory
chemicals
(solid)
1,978-25,643
17,802-
230,787
1,978-25,643
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaaed for two NAICS
codes identified.
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OES
Total Exposed
Workers ab
Total Exposed
ONUs ttb
Number of
Facilities ab
Notes
Fabrication or use of
final products or articles
N/A
Number of sites data was
unavailable for this OES. Based on
the BLS and U.S. Census Bureau
data (U.S. BLS. 2016; U.S. Census
Bureau. 2015). the average exposed
workers per site was 9, and the
average exposed ONUs per site was
3.
Recycling
754
432
58
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaged for three NAICS
codes identified.
Waste handling,
treatment, and disposal
754
432
58
Number of workers and ONU
estimates based on the BLS and
U.S. Census Bureau data (U.S.
BLS. 2016; U.S. Census Bureau.
2015). Averaged for three NAICS
codes identified.
11 EPA's approach and methodology for estimating the number of facilities using DCHP and the number of workers
and ONUs potentially exposed to DCHP can be found in the Draft Environmental Release and Occupational
Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q).
h When there is a range, the low end of the range is based on the 50th percentile estimate of the number of sites and
the upper end is based on the 95th percentile estimate of the number of sites.
4.1.1.3 Summary of Inhalation Exposure Assessment
Table 4-3 presents a summary of inhalation exposure results based on exposure modeling for each OES.
This tables provides a summary of the 8-hour time weighted average (8-hour TWA) inhalation exposure
estimates for the average adult worker, as well as the Acute Dose (AD), the Intermediate Average Daily
Dose (IADD), and the Chronic Average Daily Dose (ADD). The Draft Environmental Release and
Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q) provides
exposure results specific to women of reproductive age and ONUs. The Draft Environmental Release
and Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP) also provides additional
details regarding AD, IADD, and ADD calculations along with EPA's approach and methodology for
estimating inhalation exposures.
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Table 4-3. Summary of Average Adult Worker Inhalation Exposure Results for Each Occupational Exposure Scenario
OES
Inhalation Estimates (Average Adult Worker)
Mist 8-h TWA
(mg/m3)
PNOR 8-h TWA
(mg/m3)
AD
(mg/kg/day)
IADD
(mg/kg/day)
ADD
(mg/kg/day)
HE
CT
HE
CT
HE
CT
HE
CT
HE
CT
Manufacturing
N/A
N/A
5.0
0.48
0.63
6.0E-02
0.46
4.4E-02
0.43
4.1E-02
Import and repackaging
N/A
N/A
3.0
0.13
0.38
1.6E-02
0.28
1.2E-02
0.26
9.3E-03
Incorporation into adhesives and sealants
N/A
N/A
5.0
0.48
0.63
6.0E-02
0.46
4.4E-02
0.43
4.1E-02
Incorporation into paints and coatings
N/A
N/A
5.0
0.48
0.63
6.0E-02
0.46
4.4E-02
0.43
4.1E-02
Incorporation into other formulations, mixtures,
or reaction products
N/A
N/A
5.0
0.48
0.63
6.0E-02
0.46
4.4E-02
0.43
4.1E-02
PVC plastics compounding
N/A
N/A
4.7
0.23
0.59
2.9E-02
0.43
2.1E-02
0.40
1.8E-02
PVC plastics converting
N/A
N/A
2.1
0.10
0.26
1.3E-02
0.19
9.5E-03
0.18
7.8E-03
Non-PVC materials compounding
N/A
N/A
2.8
0.14
0.35
1.7E-02
0.26
1.3E-02
0.24
1.1E-02
Non-PVC materials converting
N/A
N/A
0.94
4.6E-02
0.12
5.8E-03
8.6E-02
4.2E-03
8.0E-02
3.5E-03
Application of paints and coatings (liquids)
8.84
0.422
N/A
N/A
1.11
5.3E-02
0.81
3.9E-02
0.76
3.6E-02
Application of paints and coatings (solids)
N/A
N/A
4.9
0.28
0.61
3.5E-02
0.45
2.6E-02
0.42
2.4E-02
Application of adhesives and sealants (liquids)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Application of adhesives and sealants (solids)
N/A
N/A
2.7
0.15
0.34
1.9E-02
0.25
1.4E-02
0.23
1.2E-02
Use of laboratory chemicals (liquids)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Use of laboratory chemicals (solids)
N/A
N/A
2.7
0.19
0.34
2.4E-02
0.25
1.7E-02
0.23
1.5E-02
Recycling
N/A
N/A
1.6
0.11
0.20
1.4E-02
0.14
9.9E-03
0.13
8.2E-03
Fabrication or use of final products or articles
N/A
N/A
0.81
0.09
0.10
1.1E-02
7.4E-02
8.3E-03
6.9E-02
7.7E-03
Waste handling, treatment, and disposal
N/A
N/A
1.6
0.11
0.20
1.4E-02
0.14
9.9E-03
0.13
8.2E-03
Abbreviations: AD = acute dose; ADD = average daily dose; CT = central tendency; HE = high-end; IADD = intermediate average daily dose; PNOR = particulates not
otherwise regulated; TWA = time-weighted average
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1126 4.1.1.4 Summary of Dermal Exposure Assessment
1127 Table 4-4 presents a summary of dermal exposure results for the average adult worker, which are based
1128 on both empirical dermal absorption data and dermal absorption modeling. The table includes the Acute
1129 Potential Dose Rate (APDR) for occupational dermal exposure estimates, as well as the AD, IADD, and
1130 Chronic ADD for the average adult worker. The Draft Environmental Release and Occupational
1131 Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q) provides exposure results
1132 for women of reproductive age and ONUs. The Draft Environmental Release and Occupational
1133 Exposure Assessment for Dicyclohexyl Phthalate (DCHP) provides additional details regarding AD,
1134 IADD, and ADD calculations along with EPA's approach and methodology for estimating dermal
1135 exposures.
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1136 Table 4-4. Summary of Average Adult Worker Dermal Exposure Results for Each PES
OES
Dermal Estimates (Average Adult Worker)
Exposure Type
APDR
(mg/day)
AD
(mg/kg/day)
IADD
(mg/kg/day)
ADD
(mg/kg/day)
Liquid
Solid
HE
CT
HE
CT
HE
CT
HE
CT
Manufacturing; Incorporation into adhesives and
sealants; Incorporation into paints and coatings;
Incorporation into other formulations, mixtures,
or reaction products; Application of paints and
coatings (solids); Use of laboratory chemicals
(solids); Fabrication or use of final products or
articles
X
0.36
0.18
4.5E-03
2.3E-03
3.3E-03
1.7E-03
3.1E-03
1.5E-03
Import and repackaging
X
0.36
0.18
4.5E-03
2.3E-03
3.3E-03
1.7E-03
3.1E-03
1.3E-03
PVC plastics compounding; PVC plastics
converting; non-PVC materials compounding;
non-PVC materials converting; Application of
adhesives and sealants (solids); Recycling; Waste
handling, treatment, and disposal
X
0.36
0.18
4.5E-03
2.3E-03
3.3E-03
1.7E-03
3.1E-03
1.4E-03
Application of paints and coatings (liquids); Use
of laboratory chemicals (liquids)
X
0.36
0.18
4.5E-03
2.3E-03
3.3E-03
1.7E-03
3.1E-03
1.5E-03
Application of adhesives and sealants (liquids)
X
0.36
0.18
4.5E-03
2.3E-03
3.3E-03
1.7E-03
3.1E-03
1.4E-03
Abbreviations: AD = acute dose; ADD = average daily dose; APDR = Acute Potential Dose Rate; CT = central tendency; HE = high-end; IADD = intermediate
average daily dose
1137
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4.1.1.5 Weight of Scientific Evidence Conclusions for Occupational Exposure
Judgment on the weight of scientific evidence is based on the strengths, limitations, and uncertainties
associated with the exposure estimates. The Agency considers factors that increase or decrease the
strength of the evidence supporting the exposure estimate—including quality of the data/information,
applicability of the exposure data to the COU (including considerations of temporal and locational
relevance) and the representativeness of the estimate for the whole industry. The best professional
judgment is summarized using the descriptors of robust, moderate, slight, or indeterminant, in
accordance with the Draft Systematic Review Protocol (U.S. EPA. 2021a). For example, a conclusion of
moderate is appropriate where exposure data is generated from a generic model with high quality data
and some chemical-specific or industry-specific inputs, such that the exposure estimate is a reasonable
representation of potential sites within the OES. A conclusion of slight weight of scientific evidence is
appropriate where there is limited information that does not sufficiently cover all potential exposures
within the COU, and the assumptions and uncertainties are not fully known or documented. See the
Draft Systematic Review Protocol for additional information on weight of scientific evidence
conclusions. Table 4-5 provides a summary of EPA's overall confidence in its occupational exposure
estimates for each of the OESs assessed.
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Table 4-5. Summary of Assumptions, Uncertainty, and Overall Confidence in Exposure Estimates by PES
OES
Weight of Scientific Evidence Conclusion in Exposure Estimates
Manufacturing
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the manufacturing OES. EPA utilized the
PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built usina OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the aeneric model identified
with the Chemical Manufacturing NAICS code (NAICS code 325) to assess this OES, which EPA expects to be the most
representative subset of the particulate data in the absence of chemical-specific data. EPA estimated the highest expected
concentration of DCHP in particulates during manufacturing using DCHP concentration information from CDR reporters, which was
also rated hiah for data qualitv in the systematic review process (U.S. EPA. 2020a). These strenaths increase the weiaht of scientific
evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day and 250 exposure days per year based on continuous DCHP exposure each working day for a
typical worker schedule; it is uncertain whether this captures actual worker schedules and exposures. EPA did not account for vapor
inhalation exposures, but vapor exposures are not expected to significantly contribute to overall inhalation exposure when compared
to particulate exposures. This is based on DCHP's vapor pressure, and the solid physical form assessed for this OES. These
limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Import and
repackaging
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the import and repackaging OES. EPA utilized
the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built usina OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the aeneric model identified
with the Wholesale and Retail Trade NAICS codes (NAICS codes 42 through 45) to assess this OES, which EPA expects to be the
most representative subset of the particulate data in the absence of chemical-specific data. EPA estimated the highest expected
concentration of DCHP in particulates during import and repackaging using DCHP concentration information from CDR reporters,
which was also rated hiah for data aualitv in the systematic review process (U.S. EPA. 2020a). These strenaths increase the weiaht
of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day and 208 to 250 exposure days per year based on continuous DCHP exposure each working
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day for atypical worker schedule; it is uncertain whether this captures actual worker schedules and exposures. EPA did not account
for vapor inhalation exposures, but vapor exposures are not expected to significantly contribute to overall inhalation exposure
compared to particulate exposures based on DCHP's vapor pressure and the solid physical form assessed for this OES. These
limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Incorporation
into adhesives
and sealants
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the incorporation into adhesives and sealants
OES. EPA utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable
particulate concentrations used by the generic model were rated high for data quality from the systematic review process, and the
model was built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic
model identified with the Chemical Manufacturing NAICS code (NAICS code 325) to assess this OES, which EPA expects to be the
most representative subset of the particulate data for chemical product manufacturing in the absence of DCHP-specific data. EPA
estimated the highest expected concentration of DCHP in particulates during adhesive and sealant manufacturing using DCHP
concentration information from CDR reporters, which was also rated high for data quality in the systematic review process (U.S.
EPA. 2020a). These strengths increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day and 250 exposure days per year based on continuous DCHP particulate exposure while
unpacking DCHP received on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker
schedules and exposures. EPA did not account for vapor inhalation exposures, but vapor exposures are not expected to significantly
contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor pressure and the solid physical
form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Incorporation
into paints and
coatings
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the incorporation into paints and coatings OES.
EPA utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable
particulate concentrations used by the generic model were rated high for data quality from the systematic review process, and the
model was built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic
model identified with the Chemical Manufacturing NAICS code (NAICS code 325) to assess this OES, which EPA expects to be the
most representative subset of the particulate data for chemical product manufacturing in the absence of DCHP-specific data. EPA
estimated the highest expected concentration of DCHP in particulates during paint and coating manufacturing using DCHP
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concentration information from CDR reporters, which was also rated high for data quality in the systematic review process (U.S.
EPA. 2020a). These strengths increase the weiaht of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day and 250 exposure days per year based on continuous DCHP particulate exposure while
unpacking DCHP received on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker
schedules and exposures. EPA did not account for vapor inhalation exposures, but vapor exposures are not expected to significantly
contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor pressure and the solid physical
form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Incorporation
into other
formulations,
mixtures, and
reaction products
not covered
elsewhere
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the incorporation into other formulations,
mixtures, and reaction products not covered elsewhere OES. EPA utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker
inhalation exposure to solid particulate. The respirable particulate concentrations used by the generic model were rated high for data
aualitv from the systematic review process, and the model was built using OSHA CEHD data (OSHA. 2020). EPA used a subset of
the respirable particulate data from the generic model identified with the Chemical Manufacturing NAICS code (NAICS code 325)
to assess this OES, which EPA expects to be the most representative subset of the particulate data for chemical product
manufacturing in the absence of DCHP-specific data. EPA estimated the highest expected concentration of DCHP in particulates
during formulation, mixture or other chemical product manufacturing using DCHP concentration information from CDR reporters,
which was also rated hiah for data qualitv in the systematic review process (U.S. EPA. 2020a). These strengths increase the weiaht
of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day and 250 exposure days per year based on continuous DCHP particulate exposure while
unpacking DCHP received on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker
schedules and exposures. EPA did not account for vapor inhalation exposures, but vapor exposures are not expected to significantly
contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor pressure and the solid physical
form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
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PVC plastics
compounding
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for PVC plastics compounding OES. EPA utilized
the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic model identified
with the Plastics and Rubber Manufacturing NAICS code (NAICS code 326) to assess this OES, which EPA expects to be the most
representative subset of the particulate data for PVC plastic manufacturing in the absence of DCHP-specific data. EPA estimated the
highest expected concentration of DCHP in particulates during PVC plastic compounding using DCHP concentration information
from CDR reporters, which was also rated high for data qualitv in the systematic review process (U.S. EPA. 2020a). These strengths
increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while unpacking DCHP received on site each
working day for a typical worker schedule; it is uncertain whether this captures actual worker schedules and exposures. EPA set the
number of exposure days based on Monte Carlo modeling of the operating days from the release assessment, with a maximum
number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures are based on 250
days per year as the exposure frequency since the 95th percentile of operating days in the release assessment exceeded 250 days per
year. The central tendency exposures use 223 days per year as the exposure frequency based on the 50th percentile of operating days
from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures are not expected to
significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor pressure and the
solid physical form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
PVC plastics
converting
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for PVC plastics converting OES. EPA utilized the
PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic model identified
with the Plastics and Rubber Manufacturing NAICS code (NAICS code 326) to assess this OES, which EPA expects to be the most
representative subset of the particulate data for PVC plastics product manufacturing in the absence of DCHP-specific data. EPA
estimated the highest expected concentration of DCHP in particulates during PVC plastic converting using plasticizer additive
concentration information from the Use of Additives in Plastic Converting Generic Scenario that was rated medium for data quality
in the systematic review process (U.S. EPA. 2004a). These strengths increase the weight of evidence.
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The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while handling DCHP-containing plastics on
site each working day for atypical worker schedule; it is uncertain whether this captures actual worker schedules and exposures.
EPA set the number of exposure days based on Monte Carlo modeling of the operating days from the release assessment, with a
maximum number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures are
based on 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment exceeded
250 days per year. The central tendency exposures use 219 days per year as the exposure frequency based on the 50th percentile of
operating days from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures are not
expected to significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor
pressure and the solid physical form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Non-PVC
material
compounding
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for non-PVC material compounding OES. EPA
utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic model identified
with the Plastics and Rubber Manufacturing NAICS code (NAICS code 326) to assess this OES, which EPA expects to be the most
representative subset of the particulate data for non-PVC plastic or rubber manufacturing in the absence of DCHP-specific data. EPA
estimated the highest expected concentration of DCHP in particulates during non-PVC material compounding using DCHP
concentration information from CDR reporters, which was also rated high for data quality in the systematic review process (U.S.
EPA. 2020a). These strengths increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while unpacking DCHP received on site each
working day for a typical worker schedule; it is uncertain whether this captures actual worker schedules and exposures. EPA set the
number of exposure days based on Monte Carlo modeling of the operating days from the release assessment, with a maximum
number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures are based on 250
days per year as the exposure frequency since the 95th percentile of operating days in the release assessment exceeded 250 days per
year. The central tendency exposures use 227 days per year as the exposure frequency based on the 50th percentile of operating days
from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures are not expected to
significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor pressure and the
solid physical form assessed for this OES. These limitations decrease the weight of evidence.
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Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Non-PVC
material
converting
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for non-PVC material converting OES. EPA
utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic model identified
with the Plastics and Rubber Manufacturing NAICS code (NAICS code 326) to assess this OES, which EPA expects to be the most
representative subset of the particulate data for non-PVC plastic and rubber product manufacturing in the absence of DCHP-specific
data. EPA estimated the highest expected concentration of DCHP in particulates during non-PVC material converting using rubber
plasticizer concentration information from the Emission Scenario Document on Additives in Rubber Industry which has a medium
rating for data qualitv in the systematic review process (OECD. 2004). These strengths increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while handling DCHP-containing plastics or
rubbers on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker schedules and
exposures. EPA set the number of exposure days based on Monte Carlo modeling of the operating days from the release assessment,
with a maximum number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures
are based on 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment
exceeded 250 days per year. The central tendency exposures use 219 days per year as the exposure frequency based on the 50th
percentile of operating days from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures
are not expected to significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP vapor
pressure and the solid physical form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Application of
adhesives and
sealants
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the application of adhesives and sealants OES.
EPA utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable
particulate concentrations used by the generic model were rated high for data quality from the systematic review process, and the
model was built using OSHA CEHD data (OSHA. 2020). EPA used the entire respirable particulate data set from the generic model
to assess this OES, since adhesives and sealants containing DCHP may be used in a variety of end-use industries. EPA estimated the
highest expected concentration of DCHP in particulates during application of adhesives and sealants using SDSs and product data
sheets from identified DCHP-containing adhesives and sealant products in solid form. These strengths increase the weight of
evidence.
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The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while handling DCHP-containing products
on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker schedules and exposures.
EPA set the number of exposure days based on Monte Carlo modeling of the operating days from the release assessment, with a
maximum number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures are
based on 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment exceeded
250 days per year. The central tendency exposures use 232 days per year as the exposure frequency based on the 50th percentile of
operating days from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures are not
expected to significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor
pressure and the solid physical form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Application of
paints and
coatings
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates. EPA used surrogate monitoring data from the ESD
on Coating Application via Spray-Painting in the Automotive Refinishing Industry, which the systematic review process rated high
for data qualitv. to estimate inhalation exposures to DCHP in the liquid form (OECD. 201 la). EPA also used the PNOR Model (U.S.
EPA. 2021b) to estimate worker inhalation exposure to solid particulate, since DCHP mav be received on site in solid form. The
respirable particulate concentrations used by the generic model were rated high for data quality from the systematic review process,
and the model was built using OSHA CEHD data (OSHA. 2020). EPA used the entire respirable particulate data set from the aeneric
model to assess this OES, since paints and coatings containing DCHP may be used in a variety of end-use industries. EPA used
SDSs and product data sheets from identified DCHP-containing products to identify product concentrations for the liquid spray and
the solid particulate assessments. A strength of this approach is that both models (for solid particulate and for mist exposure) resulted
in exposure estimates within an order of magnitude of each other. These strengths increase the weight of evidence.
The primary limitation is the lack of DCHP-specific monitoring data. Specifically, the ESD serves as a surrogate source of
monitoring data representing the level of exposure that could be expected at a typical work site for the given spray application
method, and the generic model data represents particulate concentrations in air for solids handling exposures. EPA assumes spray
applications of the coatings, so the estimates may not be representative of exposure during other coating application methods.
Additionally, it is uncertain whether the substrates coated, and products used to generate the surrogate data are representative of
those associated with DCHP-containing coatings. EPA only assessed mist or solid exposures to DCHP over a full 8-hour work shift
to estimate the level of exposure, though other activities may result in exposures other than mist or solid particulate and application
duration may be variable depending on the job site. EPA assessed 250 days of exposure per year based on workers applying coatings
on every working day, however, application sites may use DCHP-containing coatings at much lower or variable frequencies. These
limitations decrease the weight of evidence.
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Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Use of laboratory
chemicals
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for use of laboratory chemicals OES. EPA utilized
the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate
concentrations used by the generic model were rated high for data quality from the systematic review process, and the model was
built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic model identified
with the Professional, Scientific, and Technical Services NAICS code (NAICS code 54) to assess this OES, which EPA expects to be
the most representative subset of the particulate data for use of laboratory chemicals in the absence of DCHP-specific data. EPA
estimated the highest expected concentration of DCHP in particulates during laboratory use using SDSs and product data sheets from
identified lab-grade chemicals. These strengths increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while handling DCHP-containing products
on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker schedules and exposures.
EPA set the number of exposure days based on Monte Carlo modeling of the operating days from the release assessment, with a
maximum number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures are
based on 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment exceeded
250 days per year. The central tendency exposures use 232 days per year as the exposure frequency based on the 50th percentile of
operating days from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures are not
expected to significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP's vapor
pressure and the solid physical form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Fabrication or
use of final
products or
articles
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the fabrication or use of final products or
articles OES. EPA utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The
respirable particulate concentrations used by the generic model were rated high for data quality from the systematic review process,
and the model was built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the
generic model identified with the Furniture and Related Product Manufacturing NAICS code (NAICS code 337) to assess this OES,
which EPA expects to be the most representative subset of the particulate data for this OES. EPA estimated the highest expected
concentration of DCHP in particulates during product fabrication using plasticizer additive concentration information from the Use
of Additives in Plastic Converting Generic Scenario that has a medium rating for data quality from the systematic review process
(U.S. EPA. 2004a). These strengths increase the weight of evidence.
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The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. EPA also
assumed eight exposure hours per day based on continuous DCHP particulate exposure while handling DCHP-containing products
on site each working day for atypical worker schedule; it is uncertain whether this captures actual worker schedules and exposures.
EPA set the number of exposure days based on Monte Carlo modeling of the operating days from the release assessment, with a
maximum number of working days capped at 250 days per year based on EPA default assumptions. The high-end exposures are
based on 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment exceeded
250 days per year. The central tendency exposures use 232 days per year as the exposure frequency based on the 50th percentile of
operating days from the release assessment. EPA did not account for vapor inhalation exposures, but vapor exposures are not
expected to significantly contribute to overall inhalation exposure compared to particulate exposures based on DCHP vapor pressure
and the solid physical form assessed for this OES. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Recycling
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the recycling OES. EPA utilized the PNOR
Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable particulate concentrations used
by the generic model were rated high for data quality from the systematic review process, and the model was built using OSHA
CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic model identified with the
Administrative and Support and Waste Management and Remediation Services NAICS code (NAICS code 56) to assess this OES,
which EPA expects to be the most representative subset of the particulate data for this OES. EPA estimated the highest expected
concentration of DCHP in plastic using plasticizer additive concentration information from the Use of Additives in Plastic
Converting Generic Scenario that has a medium rating for data aualitv from the systematic review process (U.S. EPA. 2004a). These
strengths increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. The high-
end exposures use 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment
exceeded 250 days per year, which is the expected maximum number of working days. The central tendency exposures use 223 days
per year as the exposure frequency based on the 50th percentile of operating days from the release assessment. Also, it was assumed
that each worker is potentially exposed for 8 hours per workday; however, it is uncertain whether this captures actual worker
schedules and exposures. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
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Waste handling,
treatment, and
disposal
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the 8-hour TWA inhalation exposure estimates for the waste handling, treatment, and disposal
OES. EPA utilized the PNOR Model (U.S. EPA. 2021b) to estimate worker inhalation exposure to solid particulate. The respirable
particulate concentrations used by the generic model were rated high for data quality from the systematic review process, and the
model was built using OSHA CEHD data (OSHA. 2020). EPA used a subset of the respirable particulate data from the generic
model identified with the Administrative and Support and Waste Management and Remediation Services NAICS code (NAICS code
56) to assess this OES, which EPA expects to be the most representative subset of the particulate data for this OES. EPA estimated
the highest expected concentration of DCHP in plastic using plasticizer additive concentration information from the Use of Additives
in Plastic Converting Generic Scenario that has a medium rating for data qualitv from the systematic review process (U.S. EPA.
2004a). These strengths increase the weight of evidence.
The primary limitation is the uncertainty in the representativeness of values toward the true distribution of potential inhalation
exposures. Specifically, EPA lacks facility-specific particulate concentrations in air, and the representativeness of the data set used in
the model towards sites that actually handle DCHP is uncertain. Further, the model lacks metadata on worker activities. The high-
end exposures use 250 days per year as the exposure frequency since the 95th percentile of operating days in the release assessment
exceeded 250 days per year, which is the expected maximum number of working days. The central tendency exposures use 223 days
per year as the exposure frequency based on the 50th percentile of operating days from the release assessment. Also, it was assumed
that each worker is potentially exposed for 8 hours per workday; however, it is uncertain whether this captures actual worker
schedules and exposures. These limitations decrease the weight of evidence.
Based on these strengths and limitations, EPA has concluded that the weight of scientific evidence for this assessment is moderate
and provides a plausible estimate of exposures.
Distribution in
commerce
These exposures are assessed as part of individual OESs where the relevant activities occur.
Dermal
EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a weight of
scientific evidence conclusion for the dermal exposure estimates. EPA used dermal modeling of aaueous materials (U.S. EPA.
2023b. 2004b) to estimate occupational dermal exposures of DCHP to workers and ONUs. The modeling approach for determining
the aqueous permeability coefficient was within the range of applicability given the physical and chemical parameters of DCHP, and
the modeling approach received a medium rating through EPA's systematic review process. Additionally, the neat form of DCHP is
a solid, the concentrated formulations are paste-like, and any liquid containing DCHP has very low concentrations; therefore, it is
reasonable to assume that flux-limited absorption of aqueous DCHP serves as a reasonable upper bound for the dermal absorption of
DCHP from occupational scenarios. Additionally, EPA assumed a standard 8-hour workday and that the chemical is contacted at
least once per day. Because DCHP has low volatility and low absorption, it is possible that the chemical remains on the surface of
the skin after a dermal contact until the skin is washed. Therefore, absorption of DCHP from occupational dermal contact with
materials containing DCHP mav extend up to 8 hours per dav (U.S. EPA. 1991). For average adult workers, the surface area of
contact was assumed equal to the area of one hand {i.e., 535 cm2) for central tendency, or two hands (i.e.. 1,070 cm2) for high-end
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OES
Weight of Scientific Evidence Conclusion in Exposure Estimates
exposures (U.S. EPA. 201 la). The standard sources for exposure duration and area of contact received high ratines through EPA's
systematic review process. These strengths increase the weight of evidence.
EPA acknowledges that variations in chemical concentration and co-formulant components affect the rate of dermal absorption, and
that these variations were not considered in the occupational dermal exposure assessment in favor of an upper bound dermal
absorption estimate from flux-limited absorption of aqueous DCHP. Additionally, worker activity metadata used in the model, such
as surface area of skin contact and exposure duration, are not facility or industry-specific and are meant to address generic dermal
exposures in all OESs assessed. These limitations decrease the weight of evidence.
The occupational dermal exposure assessment for contact with materials containing DCHP was based on dermal absorption
modeling of aqueous DCHP, as well as standard occupational inputs for exposure duration and area of contact, as described above.
Based on the strengths and limitations of these inputs, EPA has concluded that the weight of scientific evidence for this assessment is
moderate and provides a plausible estimate of occupational dermal exposures.
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4.1.1.5.1 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for
the Occupational Exposure Assessment
EPA assigned overall confidence descriptions of high, medium, or low to the exposure assessments,
based on the strength of the underlying scientific evidence. When the assessment is supported by robust
evidence, the Agency's overall confidence in the exposure assessment is high; when supported by
moderate evidence, EPA's overall confidence is medium; when supported by slight evidence, the
Agency's overall confidence is low.
Strengths
The exposure scenarios and exposure factors underlying the inhalation and dermal assessment are
supported by moderate to robust evidence. Occupational inhalation exposure scenarios were informed
by moderate or robust sources of surrogate monitoring data or GSs/ESDs used to model the inhalation
exposure concentration. Exposure factors for occupational inhalation exposure include duration of
exposure, body weight, and breathing rate, which were informed by moderate to robust data sources.
A strength of the modeling assessment includes the consideration of variable model input parameters as
opposed to using a single static value. Parameter variation increases the likelihood that the true
occupational inhalation exposures fall within the range of modeled estimates. An additional strength is
that all data that EPA used to inform the modeling parameter distributions have overall data quality
ratings of either high or medium from EPA's systematic review process. Strengths associated with
dermal exposure assessment are described in Table 4-5.
Limitations
The principal limitation of the exposure assessments is uncertainty in the representativeness of the data
and models used, as there is no direct exposure monitoring data for DCHP in the literature from
systematic review. A limitation of the modeling methodologies is that most of the model input data from
GSs/ESDs, such as air speed or loss factors, are generic for the OESs and not specific to the use of
DCHP within the OESs. Additionally, the selected generic models and data may not be representative of
all chemical- or site-specific work practices and engineering controls. Limitations associated with
dermal exposure assessment are described in Table 4-5.
Assumptions
When determining the appropriate model for assessing exposures to DCHP, EPA considered the
physical form of DCHP during different OESs. DCHP may be present in various physical forms such as
a powder, mist, paste, or in solution during the various OESs. EPA assessed each respective OES
assuming the physical form of DCHP based on available product data, CDR data, and information from
applicable GSs/ESDs. The physical form of DCHP can influence exposures substantially, so EPA
assumed DCHP is present in the physical form that is most prevalent and/or most protective for the
given OES when assessing the exposures.
EPA calculated ADD values assuming workers and ONUs are regularly exposed during their entire
working lifetime, which likely results in an overestimate. Individuals may change jobs during the course
of their career such that they are no longer exposed to DCHP, and the actual ADD values become lower
than the estimates presented. Assumptions associated with dermal exposure assessment are described in
Table 4-5.
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Uncertainties
EPA addressed variability in inhalation models by identifying key model parameters and applying
statistical distributions that mathematically define the parameter's variability. The Agency defined
statistical distributions for parameters using documented statistical variations where available. Where
the statistical variation was unknown, EPA made assumptions to estimate the parameter distribution
using available literature data, such as GSs and ESDs. However, there is uncertainty as to the
representativeness of the parameter distributions because these data are often not specific to sites that
use DCHP. In general, the effects of these uncertainties on the exposure estimates are unknown as the
uncertainties may result in either overestimation or underestimation of exposures depending on the
actual distributions of each of the model input parameters. Uncertainties associated with dermal
exposure assessment are described in Table 4-5.
There are several uncertainties surrounding the estimated number of workers potentially exposed to
DCHP. First, BLS' OES employment data for each industry/occupation combination are only available
at the 3-, 4-, or 5-digit NAICS level, rather than the full 6-digit NAICS level. This lack of granularity
could result in an overestimate of the number of exposed workers if some 6-digit NAICS are included in
the less granular BLS estimates but are not likely to use DCHP for the assessed applications. EPA
addressed this issue by refining the OES estimates using total employment data from the U.S. Census'
Statistics of U.S. Businesses (SUSB). However, this approach assumes that the distribution of
occupation types (SOC codes) in each 6-digit NAICS is equal to the distribution of occupation types at
the parent 5-digit NAICS level. If the distribution of workers in occupations with DCHP exposure
differs from the overall distribution of workers in each NAICS, then this approach will result in
inaccuracy.
4.1.2 Consumer Exposures
The following subsections briefly describe EPA's approach to assessing consumer exposures and
provide exposure assessment results for each COU. The Draft Consumer and Indoor Dust Exposure
Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024c) provides additional details on the
development of approaches and the exposure assessment results. The consumer exposure assessment
evaluated exposures from individual COUs while the indoor dust assessment uses a subset of consumer
articles with large surface area and presence in indoor environments to garner COU specific
contributions to the total exposures from dust.
4.1.2.1 Summary of Consumer and Indoor Dust Exposure Scenarios and Modeling
Approach and Methodology
The main steps in performing a consumer exposure assessment are summarized below:
• Identification and mapping of product and article examples following the consumer COU table
(Table 1-1), product, and article identification.
• Compilation of products and articles manufacturing use instructions to determine patterns of use.
• Selection of exposure routes and exposed populations according to product/article use
descriptions.
• Identification of data gaps and further search to fill gaps with studies, chemical surrogates or
product and article proxies, or professional judgement.
• Selection of appropriate modeling tools based on available information and chemical properties.
• Gathering of input parameters per exposure scenario.
• Parameterization of selected modeling tools.
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Consumer products or articles containing DCHP were matched with the identified consumer COUs.
Table 4-6 summarizes the consumer exposure scenarios by COU for each product example(s), the
exposure routes, which scenarios are also used in the indoor dust assessment, and whether the analysis
was conducted qualitatively or quantitatively. The indoor dust assessment uses consumer products and
articles information for selected items with the goal of recreating the indoor environment. The subset of
consumer products and articles that can be used in the indoor dust assessment are selected for their
potential to have large surface area for dust collection, roughly larger than one square meter. Using these
criteria, EPA did not identify articles in the modeling exposure estimates to include in the indoor
assessment.
When a quantitative analysis was conducted, exposure from the consumer COUs was estimated by
modeling. Exposure via inhalation and ingestion routes were modeled using EPA's Consumer Exposure
Model (CEM), Version 3.2 (U.S. EPA. 2023b). Dermal exposures were estimated using a computational
framework implemented within a spreadsheet environment. For each exposure route, EPA used the 10th
percentile, average, and 95th percentile value of an input parameter (e.g., weight fraction, surface area)
where possible to characterize low, medium, and high exposure scenarios for a given COU. If only a
range was reported, EPA used the minimum and maximum of the range as the low and high values,
respectively. The average of the reported low and high values from the reported range was used for the
medium exposure scenario. See Draft Consumer and Indoor Dust Exposure Assessment for
DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024c) for details about the consumer modeling
approaches, sources of data, model parameterization, and assumptions.
Exposure via the inhalation route occurs from inhalation of DCHP gas-phase emissions or when DCHP
partitions to suspended particulate from direct use or application of products. However, DCHP's low
volatility is expected to result in negligible gas-phase inhalation exposures. Sorption to suspended and
settled dust is likely to occur based on monitoring data (see indoor dust monitoring data in Section
4.1.2.1) and its affinity for organic matter which is typically present in household dust. Thus, inhalation
and ingestion of suspended and settled dust is considered in this assessment. Exposure via the dermal
route can occur from direct contact with products and articles. Exposure via ingestion depends on the
product or article use patterns. Exposure can occur via direct mouthing (i.e., directly putting product in
mouth) in which the person can ingest settled dust with DCHP, or directly ingesting DCHP from
migration to saliva. Additionally, ingestion of suspended dust can occur when DCHP migrates from
product to dust or partitions from gas-phase to suspended dust.
EPA labeled CEM lifestages to match those listed in the U.S. Centers for Disease Control and
Prevention (CDC) guidelines (CDC. 2021) and the Agency's^ Framework for Assessing Health Risks
of Exposures to Children (U.S. EPA. 2006). CEM lifestages were re-labeled as follows:
• Adult (21+ years) —~ Adult
• Youth 2 (16-20 years) —~ Teenager
• Youth 1 (11-15 years) —~ Young teen
• Child 2 (6-10 years) —~ Middle childhood
• Child 1 (3-5 years) —~ Preschooler
• Infant 2 (1-2 years) —~ Toddler
• Infant 1 (<1 year) —~ Infant
EPA assessed acute, intermediate, and chronic exposures to DCHP from consumer COUs. For the acute
dose rate calculations, an averaging time of 1 day is used representing the maximum time-integrated
dose over a 24-hour period during the exposure event. The chronic dose rate is calculated iteratively at a
30-second interval during the first 24 hours and every hour after that for 60 days. Intermediate dose is
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1295 the exposure to continuous or intermittent (depending on product) use during a 30-day period, which is
1296 roughly a month. Professional judgment and product use descriptions were used to estimate events per
1297 day and per month/year for the calculation of the intermediate/chronic dose.
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Table 4-6. Summary of Consumer CPUs, Exposure Scenarios, and Exposure Routes
Consumer COU
Category
Consumer COU
Subcategory
Product/Article
Exposure Scenario and
Route
Evaluated Routes
Suspended Dust &
Vapor Inhalation
Dermal
Ingestion
Qualitative /
Quantitative d
Suspended
Dust
Settled Dust
Mouthing
Adhesives and
sealants
Adhesives and sealants
Auto or construction
bonding adhesive
Use of product in DIY°
large-scale home repair
activities. Direct contact
during use; inhalation of
emissions during use
X
X
X
Quantitative
Adhesives and
sealants
Adhesives and sealants
Adhesives for small repairs
Use of product in DIY°
small-scale home repair
activities. Direct contact
during use
X
X
X
X
Quantitative
Other articles with
routine direct contact
during normal use
including rubber
articles; plastic articles
(hard)
Other articles with routine
direct contact during
normal use including
rubber articles; plastic
articles (hard)
Small articles with the
potential for semi-routine
contact: labels,
nitrocellulose;
ethylcellulose; chlorinated
rubber; PVAc; PVC
Direct contact during use
X*
X
X
X
Quantitative
Other
Other consumer articles
that contain dicyclohexyl
phthalate from: inks, toner,
and colorants; paints and
coatings; adhesives and
sealants (e.g., paper
products, textiles, products
using cellulose film, etc.)
Outdoor coated
surfaces/seating
Direct contact during use
Xc
X
X
X
Quantitative
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Evaluated Routes
Suspended Dust &
Vapor Inhalation
Ingestion
Consumer COU
Category
Consumer COU
Subcategory
Product/Article
Exposure Scenario and
Route
Dermal
Suspended
Dust
Settled Dust
Mouthing
Qualitative /
Quantitative d
Other
Other consumer articles
that contain dicyclohexyl
phthalate from: inks, toner,
and colorants; paints and
coatings; adhesives and
sealants (e.g., paper
products, textiles, products
using cellulose film, etc.)
Small articles with the
potential for semi-routine
contact: labels, and
packaging adhesives, foil
and cellophane lacquers,
and printing inks
Direct contact during use
Xi
X
X
X
Quantitative
Other
Other consumer articles
that contain dicyclohexyl
phthalate from: inks, toner,
and colorants; paints and
coatings; adhesives and
sealants (e.g., paper
products, textiles, products
using cellulose film, etc.)
Electronics containing dye
adhesive
No exposures expected
X
X
X
X
X
Qualitative
Disposal
Disposal
Down the drain products
and articles
Down the drain and
releases to
enviromnental media
X
X
X
X
X
Qualitative
Disposal
Disposal
Residential end-of-life
disposal, product demolition
for disposal
Product and article end-
of-life disposal and
product demolition for
disposal
X
X
X
X
X
Qualitative
DIY " - Do-it-Yourself
Scenario is considered either qualitatively or quantitatively in this assessment.
* Scenario was deemed unlikely based on low volatility and small surface area, likely negligible gas and particle phase concentration for inhalation, low possibility of
mouthing based on product use patterns and targeted population age groups, and/or low possibility of dust on surface due to barriers or low surface area for dust
ingestion.
** Scenario was deemed unlikely based on low volatility and small surface area and likely negligible gas and suspended particle phase concentration.
*c Outdoor use with significantly higher ventilation minimizes inhalation.
d Quantitative applies to green check marks and qualitative applies to red "x" marks for the routes that were deemed unlikely.
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Inhalation and Ingestion Exposure Routes Modeling Approaches
Key parameters for articles modeled in CEM 3.2 are summarized in detail in Section 2 in the Draft
Consumer and Indoor Dust Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA.
2024c). Calculations, information and data sources, input parameters, and results are available in the
Draft Consumer Exposure Analysis for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024d). Generally,
and when possible, model parameters were determined based on specific articles identified in this
assessment and CEM defaults were only used where specific information was not available. A list of
some of the most sensitive input parameters for exposure from articles and products are listed below:
• weight fraction (articles and products);
• density (articles and products);
• duration of use (products);
• frequency of use for chronic, acute, and intermediate (products);
• product mass used (products);
• article surface area (articles);
• chemical migration rate to saliva (articles);
• area mouthed (articles); and
• use environment volume (articles and products).
Low, medium, and high intensity use exposure scenarios correspond to the use of reported statistics, or
single values. When different values are reported for low, medium, and high, the corresponding statistics
are the reported minimum for the low intensity use scenarios, calculated average from maximum and
minimum for the medium intensity use scenarios and reported maximum for the high intensity use
scenarios. Each input parameter listed above was parameterized according to the article-specific data
found via systematic review. If article-specific data were not available, CEM default parameters were
used., or an assumption based on article use descriptions by manufactures always leaning on the health
protective values. For example, for all scenarios, the near-field modeling option was selected to account
for a small personal breathing zone around the user during product use in which concentrations are
higher, rather than employing a single well-mixed room. A near-field volume of 1 m3 was selected. See
Section 2.1 for weight fraction selection and Section 2.2.3 for parameterization details in the Draft
Consumer and Indoor Dust Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA.
2024c).
Dermal Exposure Routes Modeling Approaches
Dermal modeling was done outside of CEM. The use of the CEM model for dermal absorption, which
relies on total concentration rather than aqueous saturation concentration, would greatly overestimate
exposure to DCHP in liquid and solid products and articles. See (U.S. EPA. 2024c) for more details. The
dermal dose of DCHP associated with use of both liquid products and solid articles was calculated in a
spreadsheet outside of CEM. See the Draft Consumer Exposure Analysis for Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024d) for details. For each product or article, high, medium, and low exposure
scenarios were developed. Values for duration of dermal contact and area of exposed skin were
determined based on the reasonably expected use for each item. In addition, high, medium, and low
estimates for dermal exposures using a flux-limited approach were calculated and applied in the
corresponding exposure scenario. Key parameters for the dermal model are shown in Section 2.3 in
(U.S. EPA. 2024c).
4.1.2.2 Modeling Dose Results by COU for Consumer and Indoor Dust
This section summarizes the dose estimates from inhalation, ingestion, and dermal exposure to DCHP in
consumer products and articles. Detailed tables of the dose results for acute, intermediate, and chronic
exposures are available in Draft Consumer Risk Calculator for Dicyclohexyl Phthalate (DCHP) (U.S.
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EPA. 2024e). Modeling dose results for acute, intermediate, and chronic exposures and data patterns are
described in Section 3 in the Draft Consumer and Indoor Dust Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024c). Generally, dermal exposures were overall highest followed by
inhalation across scenarios, COUs and lifestages. The range of inhalation doses for each scenario and
lifestage covered several orders of magnitude due to the wide range of DCHP content (weight fractions)
for adhesives, wide range of article exposure durations, and various skin contact surface area options for
the low, medium, and high scenarios. The dermal dose range was smaller for all scenarios driven
primarily by exposure durations and frequencies.
The spread of values estimated for each product or article reflects the aggregate effects of variability and
uncertainty in key modeling parameters for each item; acute dose rate for some products and articles
covers a larger range than others primarily due to a wider distribution of DCHP weight fraction values
and behavioral factors such as duration of use or contact time and mass of product used as described in
Section 2 in (U.S. EPA. 2024c). Key differences in exposures among lifestages include designation as a
product user or bystander; behavioral differences such as hand to mouth contact times, and time spent on
the floor; and dermal contact expected from touching specific articles which may not be appropriate for
some lifestages.
4.1.2.3 Weight of Scientific Evidence Conclusions for Consumer Exposure
Key sources of uncertainty for evaluating exposure to DCHP in consumer goods and strategies to
address those uncertainties are described in detail in Section 5.1 of Draft Consumer and Indoor Dust
Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024c). Generally, designation of
robust confidence suggests thorough understanding of the scientific evidence and uncertainties. The
supporting weight of scientific evidence outweighs the uncertainties to the point where it is unlikely that
the uncertainties could have a significant effect on the exposure estimate. The designation of moderate
confidence suggests some understanding of the scientific evidence and uncertainties. More specifically,
the supporting scientific evidence weighed against the uncertainties is reasonably adequate to
characterize exposure estimates. The designation of slight confidence is assigned when the weight of
scientific evidence may not be adequate to characterize the scenario, and when the assessor is making
the best scientific assessment possible in the absence of complete information and there are additional
uncertainties that may need to be considered. While the uncertainty for some of the scenarios and
parameters ranges from slight to robust the overall confidence to use the results for risk characterization
ranges from moderate to robust, depending on COU scenario. The basis for the moderate to robust
confidence in the overall exposure estimates is a balance between using parameters that will represent
various populations use patterns and lean on protective assumptions that are not excessive or
unreasonable.
4.1.2.3.1 Strength, Limitations, Assumptions, and Key Sources of Uncertainty for
the Consumer Exposure Assessment
The exposure assessment of chemicals from consumer products and articles has inherent challenges due
to many sources of uncertainty in the analysis, including variations in product formulation, patterns of
consumer use, frequency, duration, and application methods. Variability in environmental conditions
may also alter physical and/or chemical behavior of the product or article. Table 4-7 summarizes the
overall uncertainty per COU and provides a discussion of rationale used to assign the overall
uncertainty. The subsections ahead of the table describe sources of uncertainty for several parameters
used in consumer exposure modeling that apply across COUs and provide an in depth understanding of
sources of uncertainty and limitations and strengths within the analysis. The confidence to use the results
for risk characterization ranges from moderate to robust (Table 4-7).
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Product Formulation and Composition
Variability in the formulation of consumer products—including changes in ingredients, concentrations,
and chemical forms—can introduce uncertainty in exposure assessments. In addition, data were limited
for weight fractions of DCHP in consumer goods. EPA obtained DCHP weight fractions in various
products and articles from material safety sheets, databases, and existing literature. Where possible, the
Agency obtained multiple values for weight fractions for similar products or articles. The lowest value
was used in the low exposure scenario, the highest value in the high exposure scenario, and the average
of all values in the medium exposure scenario. EPA decreased uncertainty in exposure and subsequent
risk estimates in the high, medium, and low intensity use scenarios by capturing the weight fraction
variability and obtaining a better characterization of the products' and articles' varying composition
within one COU. Overall weight fraction confidence is moderate for products/articles with only one
source with descriptions on chemical testing, robust for products/articles with more than one source, and
slight for articles with only one source with unconfirmed content or little understanding on how the
information was produced. For example, when a source does not provide a description of the analysis or
the concentrations are derived from product production approaches rather than product testing.
Product Use Patterns
Consumer use patterns like frequency of use, duration of use, and methods of application are expected to
differ. Where possible, high, medium, and low default values from CEM 3.2's prepopulated scenarios
were selected for mass of product used, duration of use, and frequency of use. In instances where no
prepopulated scenario was appropriate for a specific product, low, medium, and high values for each of
these parameters were estimated based on the manufacturers' product descriptions. EPA decreased
uncertainty by selecting use pattern inputs that represent product and article use descriptions and
furthermore capture the range of possible use patterns in the high to low intensity use scenarios.
Exposure and risk estimates are considered representative of product use patterns and well characterized.
Most use patterns' overall confidence is rated robust.
Article Surface Area
The surface area of an article directly affects the potential for DCHP emissions to the environment. For
each article modeled for inhalation exposure, low, medium, and high estimates for surface area were
calculated (see Section 2 in (U.S. EPA. 2024c)). Overall, confidence in surface area is robust for articles
because there is a good understanding of the dimensions of articles and their presence in indoor
environments.
Human Behavior
CEM 3.2 has three different human activity patterns: stay-at-home, part-time out-of-the home (daycare,
school, or work), and full-time out-of-the-home. The activity patterns were developed based on the
Consolidated Human Activity Database (CHAD). For all products and articles modeled, the stay-at-
home activity pattern was selected as it is the most protective assumption.
Modeling Tool
Confidence in the model used considers whether the model has been peer-reviewed, as well as whether
it is being applied in a manner appropriate to its design and objective. The model used, CEM 3.2, has
been peer-reviewed (ERG. 2016). is publicly available, and has been applied in the manner intended by
estimating exposures associated with uses of household products and/or articles. This also considers the
default values data source(s) such as building and room volumes, interzonal ventilation rates, and air
exchange rates. Overall confidence in the proper use of CEM and the consumer exposure estimates
results modeled is robust.
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Dermal Modeling for DCHP
Experimental dermal data was identified via the systematic review process to characterize consumer
dermal exposures to liquids or mixtures and formulations containing DCHP (see Section 2.3.1 in (U.S.
EPA. 2024c). EPA has moderate understanding of the scientific evidence and the uncertainties. The
identification of uncertainties within the dermal approach is reasonably adequate to characterize
exposure estimates. The Agency has a moderate confidence in the dermal exposure to liquid and solid
products or articles modeling approach.
A source of uncertainty regarding the dermal absorption of DCHP from products or formulations stems
from the varying concentrations and co-formulants that exist in products or formulations containing
DCHP. For purposes of this draft risk evaluation, EPA assumes that the absorptive flux of DCHP serves
as an upper bound of chemical into and through the skin for dermal contact with all liquid products or
formulations and solid products/articles. Dermal contact with products or formulations that have lower
concentrations of DCHP might exhibit lower rates of flux since there is less material available for
absorption. Conversely, co-formulants or materials within the products or formulations may lead to
enhanced dermal absorption, even at lower concentrations. Therefore, it is uncertain whether the
products or formulations containing DCHP would result in decreased or increased dermal absorption.
Based on the available dermal absorption data for DCHP, EPA has made assumptions that result in
exposure assessments that are the most human health protective in nature.
Lastly, EPA notes that there is uncertainty with respect to the modeling of dermal absorption of DCHP
from solid matrices or articles and liquid products and formulations. Because there were no available
data related to the dermal absorption of DCHP from solid matrices or articles and liquid products, EPA
has assumed that dermal absorption of DCHP from solid objects would be limited by aqueous solubility
of DCHP. Therefore, to determine the maximum steady-state aqueous flux of DCHP, EPA utilized CEM
(U.S. EPA. 2023b) to first estimate the steady-state aqueous permeability coefficient of DCHP. The
estimation of the steady-state aqueous permeability coefficient within CEM (U.S. EPA. 2023b) is based
on a quantitative structure-activity relationship (QSAR) model presented by ten Berge (2009). which
considers chemicals with log(Kow) ranging from -3.70 to 5.49 and molecular weights ranging from 18 to
584.6. The molecular weight of DCHP falls within the range suggested by ten Berge (2009). as does the
log(Kow) of DCHP. Therefore, there is a low to medium (due to assumptions used in migration of DCHP
from solid to aqueous media) uncertainty regarding the accuracy of the QSAR model used to predict the
steady-state aqueous permeability coefficient for DCHP.
Table 4-7. Weight o
'Scientific Evidence Summary per Consumer Condition of Use
Consumer COU
Category and
Subcategory
Weight of Scientific Evidence
Overall
Confidence
Adhesives and
sealants
Two different scenarios were assessed under this COU for products with
differing use patterns for which each scenario had a varying number of
identified product examples (in parentheses): adhesives for small repairs
(2) and automotive adhesives (3). The two scenarios and the products
within capture the variability in product formulation and are represented
in the high, medium, and low intensity use estimates. The overall
confidence in this COU inhalation exposure estimate is robust because
the CEM default parameters represent actual use patterns and location of
use.
For dermal exposure EPA used a dermal flux approach; moderate
confidence was selected for this approach because uncertainty in the
Inhalation -
Robust
Dermal -
Moderate
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Consumer COU
Category and
Subcategory
Weight of Scientific Evidence
Overall
Confidence
partitioning from product to skin and subsequent dermal absorption is
not well characterized or confirmed with experimental results. However,
other parameters like frequency and duration of use, and surface area in
contact are well understood and representative, making the overall
confidence in a health protective estimate moderate.
Other articles with
routine direct contact
during normal use
including rubber
articles; plastic
articles (hard)
One scenario was assessed under this COU. The scenario considered
multiple articles and routine dermal contact with similar use patterns.
The scenario for small articles of routine dermal contact was assessed for
dermal exposures only because inhalation and ingestion would have low
exposure potential due to the small surface area of the articles. The
articles with routine contact scenario considered multiple input
parameters used in the high, medium, and low intensity use scenarios.
The dermal absorption estimate assumes that dermal absorption of
DCHP from solid objects would be limited by the aqueous solubility of
DCHP. EPA has slight confidence in the aspects of the exposure
estimate for solid articles because of the high uncertainty in the
assumption of partitioning from solid to liquid, and because subsequent
dermal absorption is not well characterized. However, other parameters,
such as frequency and duration of use as well as surface area in contact,
are well understood and representative, resulting in an overall confidence
of moderate in a health protective estimate.
Dermal -
Moderate
Other; Other
consumer articles that
contain dicyclohexyl
phthalate from: inks,
toner, and colorants;
paints and coatings;
adhesives and
sealants (e.g., paper
products, textiles,
products using
cellulose film, etc.)
Two different scenarios were assessed under this COU for articles with
differing use patterns. The scenarios of outdoor seating (single article in
use), and small articles with potential for routine contact (multiple
articles) were evaluated. These two scenarios were assessed for dermal
exposures. Dermal absorption estimates assumed that dermal absorption
of DCHP from solid objects would be limited by the aqueous solubility
of DCHP. EPA has slight confidence in the aspects of the exposure
estimate for solid articles because of the high uncertainty in the
assumption of partitioning from solid to liquid, and because subsequent
dermal absorption is not well characterized. However, other parameters
such as frequency and duration of use, and surface area in contact, are
well understood and representative, resulting in an overall confidence of
moderate in a health protective estimate.
Dermal -
Moderate
4.1.3 General Population Exposures to Environmental Releases
General population exposures occur when DCHP is released into the environment and the environmental
media are then a pathway for exposure. As described in the Draft Environmental Release and
Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q). releases of
DCHP are expected in air, water, and disposal to landfills. Figure 4-2 provides a graphic representation
of where and in which media DCHP is estimated to be found due to environmental releases and the
corresponding route of exposure for the general population.
EPA took a screening4evel approach to assess DCHP exposure to environmental releases for the general
population. Screening level assessments are useful when there is little facility location- or scenario-
specific information available. EPA began its DCHP general population exposure assessment using a
screening-level approach because of limited environmental monitoring data for DCHP and lack of
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location data for DCHP releases. A screening-level analysis relies on conservative assumptions,
including default input parameters for modeling exposure, to assess exposures that would be expected to
be on the high end of the expected exposure distribution. Details on the use of screening-level analyses
in exposure assessment can be found in EPA's Guidelines for Human Exposure Assessment (U.S. EPA.
2019b).
EPA considered fenceline populations in proximity to releasing facilities as part of the ambient air
exposure assessment by utilizing pre-screening methodology described in EPA's Draft TSCA Screening
Level Approach for Assessing Ambient Air and Water Exposures to Fenceline Communities (Version
1.0) ( J.S. EPA. 2022b). For other exposure pathways, EPA's screening method assessing high-end
exposure scenarios used release data that reflect exposures expected to occur in proximity to releasing
facilities, which would include fenceline populations.
EPA evaluated the reasonably available information for releases of DCHP from facilities that use,
manufacture, or process DCFIP under industrial and/or commercial COUs subject to TSCA regulations
detailed in the Draft Environmental Release and Occupational Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) ((J.S. EPA. 2024c). As described in Section 3.3, using the release data, EPA modeled
predicted concentrations of DCFIP in surface water, sediment, drinking water, and ambient air in the
United States. Table 3-6 summarizes the high-end DCFEP concentrations in environmental media from
environmental releases. The reason for assessing different pathways qualitatively or quantitatively is
discussed briefly in Section 3.3, and additional detail can be found in Draft Environmental Media,
General Population, and Environmental Exposure Assessment for Dicyclohexyl Phthalate (DCHP)
(U.S. EPA. 2024p).
Ambient Air
Inhalation
Landfills
(Industrial or
Muncipal)
Wastewater
Facility
$k. H
|
Soil and
Dust
Oral,
Inhalation
¦rrj
Aquatic and ^
Terrestrial
Animal
Ingestion
Oral a
Drinking
Water
Treatment
Drinking
Bathing
Water
Dermal.
Inhalation
Water
Recreation
Oral. Derma/
| Sediment |
Surface Water
Groundwater pump
Figure 4-2. Potential Human Exposure Pathways to DCHP Environmental Releases for the
General Population
Potential routes of exposure are shown in italics under each potential pathway of exposure.
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High-end estimates of DCHP concentration in the various environmental media presented in Table 3-6
and in the Draft Environmental Media, General Population, and Environmental Exposure Assessment
for DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024p) were used for screening-level purposes in the
general population exposure assessment. EPA's Guidelines for Raman Exposure Assessment (U.S. EPA.
2019b) defines high-end exposure estimates as a "plausible estimate of individual exposure for those
individuals at the upper end of an exposure distribution, the intent of which is to convey an estimate of
exposure in the upper range of the distribution while avoiding estimates that are beyond the true
distribution." If risk is not found for these individuals with high-end exposure, no risk is anticipated for
central tendency exposures, which is defined as "an estimate of individuals in the middle of the
distribution." Plainly, if there is no risk for an individual identified as having the potential for the highest
exposure associated with a COU for a given pathway of exposure, then that pathway was determined not
to be a pathway of concern and not pursued further. If any pathways were identified as a pathway of
concern for the general population, further exposure assessments for that pathway would be conducted
to include higher tiers of modeling when available, refinement of exposure estimates, and exposure
estimates for additional subpopulations and OES/COUs.
Identifying individuals at the upper end of an exposure distribution included consideration of high-end
exposure scenarios defined as those associated with the industrial and commercial releases from a COU
and OES that resulted in the highest environmental media concentrations. As described in Section 3.3,
EPA focused on estimating high-end concentrations of DCHP from the largest estimated releases for the
purpose of its screening level assessment for environmental and general population exposures. This
means that the Agency considered the environmental concentration of DCHP in a given environmental
medium resulting from the OES that had the highest release compared to any other OES for the same
releasing media. Release estimates from OES resulting in lower environmental media concentrations
were not considered for this screening-level assessment. Additionally, individuals with the greatest
intake rate of DCHP per body weight were considered to be those at the upper end of the exposure.
Table 4-8 summarizes the high-end exposure scenarios that were considered in the screening level
analysis, including the lifestage assessed as the most potentially exposed population based on intake rate
and body weight. It also indicates which pathways were evaluated quantitatively or qualitatively.
Exposure was assessed quantitatively only when environmental media concentrations were quantified
for the appropriate exposure scenario. For example, exposure from groundwater resulting from DCHP
release to the environment via biosolids or landfills was not quantitatively assessed because
environmental releases from biosolids and landfills were not quantified. Due to the high confidence in
the biodegradation rates and physical and chemical data, there is robust confidence that DCHP in soils
will not be mobile and will have low persistence potential. There is robust confidence that DCHP is
unlikely to be present in landfill leachates. However, exposure was still assessed qualitatively for
exposures potentially resulting from biosolids and landfills. Further details on the screening level
approach and exposure scenarios evaluated by EPA for the general population are provided in the Draft
Environmental Media, General Population, and Environmental Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024pV Selected OESs represent those resulting in the highest modeled
environmental media concentrations for the purpose of a screening-level analysis. A crosswalk between
OESs and COUs is presented in Section 3.1.1.1.
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Table 4-8. Exposure Scenarios Assessed in General Population Screening Level Analysis
OES
Exposure
Pathway
Exposure
Route
Exposure Scenario
Lifestage
Analysis
(Quantitative or
Qualitative)"
All
Biosolids
No specific exposure scenarios were assessed for
qualitative assessments
Qualitative
Section 3.1
All
Landfills
No specific exposure scenarios were assessed for
qualitative assessments
Qualitative
Section 3.2
PVC plastics
compounding
Surface
Water
Dermal
Dermal exposure to
DCHP in surface water
during swimming
Adults,
youths, and
children
Quantitative
Section 5.1.1
Oral
Incidental ingestion of
DCHP in surface water
during swimming
Adults,
youths, and
children
Quantitative
Section 5.1.2
PVC plastics
compounding
Drinking
Water
Oral
Ingestion of drinking
water
Adults,
youths, and
children
Quantitative
Section 6
All
Fish
Ingestion
Oral
Ingestion of fish for
General Population
Adults and
children
Quantitative
Section 7.1
PVC plastics
compounding
Ingestion of fish for
subsistence fishers
Adult
Quantitative
Section 7.2
PVC plastics
compounding
Ingestion of fish for
Tribal populations
Adult
Quantitative
Section 7.3
Application of
paints, coatings,
adhesives, and
sealants
Ambient Air
Inhalation
Inhalation of DCHP in
ambient air resulting
from industrial
releases
All
Quantitative
Section 9
"Note the references are to sections in Draft Environmental Media, General Population, and Environmental Exposure
Assessment for Dicvclohexvl Phthalate (DCHP) (U.S. EPA. 2024b) and no! this document.
EPA also considered urinary biomonitoring data, from CDC's National Health and Nutrition
Examination Survey (NHANES) (see Section 11 of EPA's Draft Environmental Media, General
Population, and Environmental Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA.
2024p)). The Agency analyzed urinary data for MCHP (mono-cyclohexyl phthalate, a metabolite of
DCHP) measured in the 1999 to 2010 NHANES cycle. Low detection rates and limited variability in
data precluded any meaningful statistical analyses. CDC stopped collecting urinary data for MCHP after
2010. Furthermore, EPA's systematic review process did not identify any suitable alternative sources of
DCHP biomonitoring data fit for use in this risk evaluation Those studies were not considered because
they used NHANES data, had very low (<30%) detection levels, evaluated very specific study
populations (e.g., a cohort examining specific health concerns), or were not measured in the United
States. Given the lack of recent urinary biomonitoring data, EPA did not conduct reverse dosimetry to
calculate daily intake values for DCHP.
4.1.3.1 General Population Screening Level Exposure Assessment Results
Land Pathway
EPA evaluated general population exposures via the land pathway (i.e., application of biosolids,
landfills) qualitatively. Due to low water solubility (1.48 mg/L) and affinity for sorption to soil and
organic constituents in soil (log Koc = 4.47), DCHP is unlikely to migrate to groundwater via runoff
after land application of biosolids. Additionally, the half-life of 8.1 to 13.8 days in aerobic soils (U.S.
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EPA. 2024z) indicates that DCHP will have low persistence potential in the aerobic environments
associated with freshly applied biosolids. Because the physical and chemical properties of DCHP
indicate that it is unlikely to migrate from land applied biosolids to groundwater via runoff, EPA did not
model groundwater concentrations resulting from land application of biosolids.
Although there are no measured data on DCHP in landfill leachates, the potential to leach from landfills
into nearby groundwater or surface water systems is limited. Interpretation of the high-quality physical
and chemical property data indicates that DCHP is expected to have a high affinity to particulate (log
Koc = 4.47) and organic media (log Kow = 4.82). This will cause significant retardation in groundwater
and limit leaching to groundwater. Because of its high hydrophobicity and high affinity for soil sorption,
it is unlikely that DCHP will migrate from landfills via groundwater infiltration or surface runoff.
Therefore, EPA concludes that further assessment of DCHP in landfill leachate is not needed.
Surface Water Pathway — Incidental Ingestion and Dermal Contact from Swimming
EPA conducted modeling of releases to surface water at the point of release (i.e., in the immediate water
body receiving the effluent) to estimate the resulting environmental media concentrations from TSCA
COUs. EPA conducted modeling with the U.S. EPA's Variable Volume Water Model with Point Source
Calculator tool (PSC) to estimate concentrations of DCHP within surface water and to estimate settled
sediment in the benthic region of streams. Releases associated with the PVC plastics compounding OES
resulted in the highest total water column concentrations, with 30Q5 water concentrations of 126 |ig/L
without wastewater treatment and 39.6 |ig/L when run under an assumption of 68.6 percent wastewater
treatment removal efficiency (Table 4-9). Both treated and untreated scenarios were assessed due to
uncertainty about the prevalence of wastewater treatment from discharging facilities and to demonstrate
the hypothetical disparity in exposures between treated and untreated effluent in the generic release
scenarios. COUs mapped to this OES are shown in Table 3-1. These water column concentrations were
used to estimate the ADR from dermal exposure and incidental ingestion of DCHP while swimming for
adults (2+ years), youths (11-15 years), and children (6-10 years). Exposure scenarios leading to the
highest modeled ADR are shown in Table 4-9.
Surface Water Pathway — Drinking Water
For the drinking water pathway, modeled surface water concentrations were used to estimate drinking
water exposures. For screening-level purposes, only the OES scenario resulting in the highest modeled
surface water concentrations, PVC plastics compounding, was included in the drinking water exposure
analysis. COUs mapped to this OES are shown in Table 3-1. EPA evaluated drinking water scenarios
that assumed a wastewater treatment removal efficiency of 68.6 percent and no further drinking water
treatment (Table 4-9). ADR and ADD values from drinking water exposure to DCHP were calculated
for various age groups but the most exposed lifestage, infants (birth to <1 year), is shown below.
Exposure scenarios leading to the highest ADR and ADD are shown in Table 4-9.
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Table 4-9. Summary of the Highest Doses in the General Population through Surface and
Drinking Water Exposure
OESfl
Water Column
Concentrations
Incidental
Dermal Surface
Water6
Incidental
Ingestionc
Drinking Waterrf
30Q5 Cone.
(^g/L)
ADRpot (mg/kg-
day)
ADRpot
(mg/kg-day)
ADRpot (mg/kg-
day)
PVC plastics compounding
without wastewater treatment
126
1.1E-03
6.7E-04
1.8E-02
PVC plastics compounding
With Wastewater Treatment
39.6
3.50E-04
2.1E-04
5.6E-03
11 Only this OES was used in the screening assessment because it resulted in the highest surface water concentrations.
Table 3-1 provides a crosswalk of industrial and commercial COUs to OES.
h Most exposed age group: Adults (21+ years)
c Most exposed age group: Youth (11-15 years)
d Most exposed age group: Infant (birth to <1 year)
Fish Ingestion
The key parameters to estimate human exposure to DCHP via fish ingestion are the surface water
concentration, bioaccumulation factor (BAF), and fish ingestion rate. Surface water concentrations for
DCHP associated with a particular COU were modeled using VVWM-PSC as described in Section
3.3.1.1. EPA used the PVC plastics compounding OES that resulted in the highest modeled DCHP
concentrations in surface water, as well as various flow rates, in its screening4evel analysis. The details
on the BAF, which considers the animal's uptake of a chemical from both diet and the water column,
can be found in Section 8 of the Draft Environmental Media, General Population, and Environmental
Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024pY
EPA evaluated exposure to DCHP through fish ingestion for populations and age groups that had the
highest fish ingestion rate per kg of body weight—including for adults and young toddlers in the general
population, adult subsistence fishers, and adult Tribal populations. Only the fish ingestion rate changes
for across the different populations; the surface water concentration and BAF remain the same. ADR
and ADD values from fish ingestion exposure to DCHP were calculated for various populations and age
groups and can be found in Draft Environmental Media, General Population, and Environmental
Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024p). but Table 4-10 shows
only the scenarios leading to the highest exposure.
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Table 4-10. Summary of the Highest Doses for Fis
l Ingestion for Adults in Tribal Populations
Calculation Method
Current Mean Ingestion
Rate b
Heritage Ingestion
Rate b
ADR/ADD
(mg/kg-day) a
ADR/ADD
(mg/kg-day) a
Water solubility limit (1.48 mg/L)
2.68E-01
2.04
Modeled SWC for PVC plastics compounding, P50
flow (0.087 mg/L)
1.59E-02
1.21E-01
Modeled SWC for PVC plastics compounding, P75
flow (3.48E-03mg/L)
6.30E-04
4.80E-03
Modeled SWC for PVC plastics compounding, P90
flow (2.4E-04mg/L)
4.40E-05
3.35E-04
Highest monitored SWC (1.0E-05 mg/L)
2.53E-06
1.93E-05
SWC = surface water concentration
11 Current ingestion rate refers to the present-day consumption levels that are suppressed by contamination,
degradation, or loss of access. Heritage rates existed prior to non-indigenous settlement on Tribal fisheries resources
and changes to culture and lifeway.
h The ADR and ADDs are identical because the inputs to estimating both exposure scenarios are identical.
Ambient Air Pathway
As part of the ambient air exposure assessment, EPA considered exposures to the general population in
proximity to releasing facilities, including fenceline communities, by utilizing pre-screening
methodology described in EPA's Draft TSCA Screening Level Approach for Assessing Ambient Air and
Water Exposures to Fenceline Communities (Version 1.0) (U.S. EPA. 2022b). EPA used the IIOAC to
estimate ambient air concentrations using pre-run results from a suite of dispersion scenarios in a variety
of meteorological and land-use settings within EPA's American Meteorological Society/EPA
Regulatory Model (AERMOD). The highest modeled 95th percentile annual ambient air concentration
across all release scenarios was 67.57 |ig/m3 at 100 m from the releasing facility for the Application of
paints and coatings OES (Table 3-6). COUs mapped to this OES are shown in Table 3-1. This OES was
the only one assessed for the purpose of a screening-level assessment as it was associated with the
highest ambient air concentration (see Section 13 of Draft Environmental Media, General Population,
and Environmental Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024p) for
more details).
Table 4-11. General
'opulation Ambient Air Exposure Summary
OES"
Acute (Daily Average)b
Chronic (Annual Average) b
Air Concentration c
(|ig/m3)
AC
(mg/kg-day)
Air Concentration c
(|ig/m3)
ADC
(mg/kg-day)
Application of
paints and coatings
67.57
67.57
46.28
46.28
AC = acute concentration; ADC = average daily concentration
"Table 3-1 provides a crosswalk of industrial and commercial COUs to OES.
h EPA assumes the general population is continuously exposed (i.e., 24 hours per day, 365 days per year) to
outdoor ambient air concentrations. Therefore, daily average modeled ambient air concentrations are equivalent
to acute exposure concentrations, and annual average modeled ambient air concentrations are equivalent to
chronic exposure concentrations.
c Air concentrations are reported for the high-end (95th percentile) modeled value at 100 m from the emitting
facility and stack plus fugitive releases combined.
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4.1.3.1 Overall Confidence in General Population Screening Level Exposure
Assessment
The weight of scientific evidence supporting the general population exposure to environmental releases
estimate is decided based on the strengths, limitations, and uncertainties associated with the exposure
estimates, which are discussed in detail for ambient air, surface water, drinking water, and fish ingestion
in the Draft Environmental Media, General Population, and Environmental Exposure Assessment for
DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024p). EPA summarized its weight of scientific evidence
using confidence descriptors: robust, moderate, slight, or indeterminate. The Agency used general
considerations (i.e., relevance, data quality, representativeness, consistency, variability, uncertainties) as
well as chemical-specific considerations for its weight of scientific evidence conclusions.
EPA determined robust confidence in its qualitative assessment of biosolids and landfills. For its
quantitative assessment, the Agency modeled exposure due to various general population and
environmental release exposure scenarios resulting from different pathways of exposure. Exposure
estimates used high-end inputs for the purpose of risk screening. When available, monitoring data were
compared to modeled estimates to evaluate overlap, magnitude, and trends. EPA has robust confidence
that modeled releases used are appropriately conservative for a screening level-analysis. Therefore, EPA
has robust confidence that no exposure scenarios will lead to greater doses than presented in this draft
risk evaluation. Despite slight and moderate confidence in the estimated values themselves, confidence
in exposure estimates capturing high-end exposure scenarios was robust given that many of the modeled
values exceeded those of monitored values.
4.1.4 Human Milk Exposures
Infants are a potentially susceptible subpopulation because of their higher exposure per body weight,
immature metabolic systems, and the potential for chemical toxicants to disrupt sensitive developmental
processes—among other reasons. Reasonably available information from studies of experimental animal
models also indicates that DCHP is a developmental toxicant (U.S. EPA. 2024v). EPA considered
exposure and hazard information, as well as pharmacokinetic models, to determine the most
scientifically supportable appropriate approach to evaluate infant exposure to DCHP from human milk
ingestion (U.S. EPA. 2024p).
EPA identified two studies from Germany that measured DCHP concentrations in human milk. Neither
of the studies characterized the possibility of occupational exposure to DCHP. No U.S. biomonitoring
studies were identified. It is important to note that biomonitoring data do not distinguish between
exposure routes or pathways and do not allow for source apportionment. In other words, biomonitoring
data reflect total infant exposure through human milk ingestion and the contribution of specific TSC A
COUs to overall exposure cannot be determined.
Furthermore, no human health studies have evaluated only lactational exposure from quantified levels of
DCHP in milk. Uncertainties in the toxic moiety for DCHP and the limited half-life data of its
metabolites in the human body that are both sensitive and specific also precluded modeling human milk
concentrations by COUs. However, EPA has robust confidence that not modeling human milk
concentrations is still protective of a nursing infant because multigenerational studies were evaluated to
derive the hazard values. The multigenerational studies observed the effects on offspring across at least
three generations resulting from maternal exposure during lactation, gestation, and other exposure
periods. The hazard values are thus expected to protect a nursing infant's greater susceptibility during
this unique lifestage whether due to sensitivity or greater exposure per body weight. Further discussion
of the human milk pathway is provided in the Draft Environmental Media, General Population, and
Environmental Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024p).
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4.1.5 Aggregate and Sentinel Exposure
TSCA section 6(b)(4)(F)(ii) (15 U.S.C. 2605(b)(4)(F)(ii)) requires EPA, in conducting a risk evaluation,
to describe whether aggregate and sentinel exposures under the COUs were considered and the basis for
their consideration.
EPA defines aggregate exposure as "the combined exposures to an individual from a chemical substance
across multiple routes and across multiple pathways (40 CFR 702.33)." For the draft DCHP risk
evaluation, the Agency considered aggregate risk across all routes of exposure for each individual
consumer and occupational COU evaluated for acute, intermediate, and chronic exposure durations.
EPA did not consider aggregate exposure for the general population exposed to environmental releases.
As described in Section 4.1.3, the Agency employed a risk screen approach for the general population
exposure assessment. Based on results from the risk screen, no pathways of concern (i.e., ambient air,
surface water, drinking water, fish ingestion) to DCHP exposure were identified for the generation
population.
EPA did not consider aggregate exposure scenarios across COUs because the Agency did not find any
evidence to support such an aggregate analysis, such as statistics of populations using certain products
represented across COUs or workers performing tasks across COUs. However, EPA considered
combined exposure across all routes of exposure for each individual occupational and consumer COU to
calculate aggregate risks (Sections 4.3.2 and 4.3.3).
EPA defines sentinel exposure as "the exposure to a chemical substance that represents the plausible
upper bound of exposure relative to all other exposures within a broad category of similar or related
exposures (40 CFR 702.33)." In terms of this draft risk evaluation, EPA considered sentinel exposures
by considering risks to populations who may have upper bound exposures; for example, workers and
ONUs who perform activities with higher exposure potential, or consumers who have higher exposure
potential or certain physical factors like body weight or skin surface area exposed. The Agency
characterized high-end exposures in evaluating exposure using both monitoring data and modeling
approaches. Where statistical data are available, EPA typically uses the 95th percentile value of the
available data set to characterize high-end exposure for a given COU. For general population and
consumer exposures, the Agency occasionally characterized sentinel exposure through a "high-intensity
use" category based on elevated consumption rates, breathing rates, or user-specific factors.
4.2 Summary of Human Health Hazards
4.2.1 Background
This section briefly summarizes the non-cancer and cancer human health hazards of DCHP (Section
4.2.2 and 4.2.3). Additional information on the non-cancer and cancer human health hazards of DCHP
are provided in the Draft Non-Cancer Raman Health Hazard Assessment for Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024v) and Draft Cancer Human Health Hazard Assessment for Di(l-ethylhexyl)
Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobiityl Phthalate
(DIBP), and Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2025a).
4.2.2 Non-cancer Human Health Hazards of DCHP
EPA identified effects on the developing male reproductive system as the most sensitive and robust non-
cancer hazard associated with oral exposure to DCHP in experimental animal models. Existing
assessments of DCHP—including (U.S. CPSC. 2014. 2010). (ECCC/HC. 2020; EC/HC. 20151 (ECHA.
2014). and (NICNAS. 2016. 2008)—also consistently identified effects on the developing male
reproductive system as a sensitive and robust non-cancer effect following oral exposure to DCHP. EPA
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also considered epidemiologic evidence qualitatively as part of hazard identification and
characterization. However, epidemiologic evidence from the one DCHP study was not considered
further for dose-response analysis due to limitations and uncertainties in exposure characterization that
are discussed further in the Draft Non-cancer Raman Health Hazard Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024v). Use of epidemiologic evidence qualitatively is consistent with
phthalates assessments by Health Canada and U.S. CPSC.
EPA is proposing a point of departure (POD) of 10 mg/kg-day (human equivalent dose [HED] of 2.4
mg/kg-day) based on phthalate syndrome-related effects on the developing male reproductive system
(decreased fetal testicular testosterone; decreased AGD; Leydig cell effects; decreased mRNA and/or
protein expression of steroidogenic genes; decreased protein expression of INSL3) to estimate non-
cancer risks from oral exposure to DCHP for acute, intermediate, and chronic durations of exposure in
the draft risk evaluation of DCHP. The proposed POD is the most sensitive no-observed-adverse-effect
level (NOAEL) and is further supported by one study reporting aNOAEL of 17 mg/kg-day (Hoshino et
al.. 2005) and four other studies reporting effects on the developing male reproductive system consistent
with a disruption of androgen action and phthalate syndrome in rats at lowest-observed-adverse-effect
(LOAELs) ranging from 20 to 33 mg/kg-day (Ahbab et al.. 2017; Ahbab and Barlas. 2015; Furr et al..
2014; Ahbab and Barlas. 2013). The Agency has performed 3/4 body weight scaling to yield the HED and
is applying the animal to human uncertainty factor (i.e., interspecies uncertainty factor; UFa) of 3 and
the within human variability uncertainty factor an (i.e., intraspecies uncertainty factor; UFh) of 10. Thus,
a total UF of 30 is applied for use as the benchmark MOE.
Overall, based on the strengths, limitations, and uncertainties discussed in the Draft Non-Cancer Human
Health Hazard Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024v). EPA has robust
overall confidence in the proposed POD based on adverse effects on the developing male reproductive
system (i.e., phthalate syndrome, which results from decreased fetal testicular testosterone). This POD
will be used to characterize risk from exposure to DCHP for acute, intermediate, and chronic exposure
scenarios.
The applicability and relevance of this POD for all exposure durations (acute, intermediate, and chronic)
is described in the Draft Non-Cancer Human Health Hazard Assessment for Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024v). For purposes of assessing non-cancer risks, the selected POD is considered
most applicable to women of reproductive age, pregnant women, male infants, and male children. Use of
this POD to assess risk for other age groups (e.g., adult males, and the elderly) is considered to be
conservative and appropriate for a screening-level assessment for these other age groups.
No data are available for the dermal or inhalation routes that are suitable for deriving route-specific
PODs. Therefore, EPA is using the acute/intermediate/chronic oral POD to evaluate risks from dermal
exposure to DCHP. Differences between oral and dermal absorption are accounted for in dermal
exposure estimates in the draft risk evaluation for DCHP. For the inhalation route, EPA is extrapolating
the oral HED to an inhalation human equivalent concentration (HEC) per EPA's Methods for Derivation
Of Inhalation Reference Concentrations and Application of Inhalation Dosimetry (U.S. EPA. 1994)
using the updated human body weight and breathing rate relevant to continuous exposure of an
individual at rest provided in EPA's Exposure Factors Handbook: 2011 Edition (U.S. EPA. 201 lb). The
oral HED and inhalation HEC values selected by EPA to estimate non-cancer risk from
acute/intermediate/chronic exposure to DCHP in the draft risk evaluation of DCHP are summarized in
Table 4-12.
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Table 4-12. Non-cancer HECs and HEDs Used to Estimate Risks
Exposure
Scenario
Target
Organ
System
Species
Duration
POD
(mg/kg-
day)
Effect at
LOAEL
HED "
(mg/
kg-
day)
HEC "
(mg/m3)
[ppm]
Benchmark
MOE b
Reference
Acute,
intermed.,
chronic
Developing
male
reproductive
system
Rat
10 days
during
gestation
NOAEL=
10 c
Phthalate
syndrome-related
effects (e.g., J,
fetal testicular
testosterone; j
AGD; Ley dig
cell effects; j
mRNA and/or
protein
expression of
steroidogenic
genes; J.INSL3)
2.4
13
[0.95]
UFa= 3
UFH=10
Total
UF=30
(Li et al..
2016)
HEC = human equivalent concentration; HED = human equivalent dose; MOE = margin of exposure; NOAEL = no-
observed-adverse-effect level; LOAEL = lowest-observed-adverse-effect level; POD = point of departure; UF = uncertainty
factor
" HED and HEC values were calculated based on the most sensitive NOAEL of 10 mg/kg-day.
b EPA used allometric bodv weieht scalins to the 3/i rower to derive the HED. Consistent with EPA Guidance (U.S. EPA.
201 lc). the interspecies uncertainty factor (UF -,). was reduced from 10 to 3 to account remaining uncertainty associated
with interspecies differences in toxicodynamics. The Agency used a default intraspecies (UFH) of 10 to account for variation
in sensitivity within human populations.
c Statistically significant effects at 10 mg/kg-day are limited to fetal Ley dig cell effects, decreased expression of genes and
proteins involved in steroidogenesis, and decreased protein expression of INSL3 (all of which are not considered adverse in
isolation). The remaining effects listed reached statistical significance at higher doses.
^4.2.3 Cancer Human Health Hazards of DCHP
DCHP has not been evaluated for carcinogenicity in any 2-year cancer bioassays. EPA therefore
evaluated the relevance of read-across approaches to assess potential cancer hazards of DCHP based on
cancer bioassays and MOA information available for other phthalates being evaluated under TSCA (i.e.,
DEHP, DBP, BBP, DINP, DIDP) as discussed in the Draft Cancer Raman Health Hazard Assessment
for Di(2-ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP),
DiisobutylPhthalate (DIBP), andDicyclohexylPhthalate (DCHP) (U.S. EPA. 2025a). (Note: EPA
plans to release the draft cancer assessment for peer review by the SACC and public comment in early
2025.)
EPA used elements of the Rethinking Chronic Toxicity and Carcinogenicity Assessment for
Agrochemicals Project (ReCAAP) weight of evidence framework (Hilton et al.. 2022) to determine the
need for carcinogenicity studies for DCHP. The framework takes into consideration multiple lines of
evidence to support decision-making for the chemical(s) of interest—including information pertaining to
nomenclature, physical and chemical properties; exposure and use patterns; absorption, distribution,
metabolism, and excretion (ADME) properties; and toxicological data (e.g., genetic toxicity, acute
toxicity, subchronic toxicity, hormone perturbation, immunotoxicity, and mode of action [MOA]). The
framework was developed by a workgroup comprising scientists from academia, government, non-
governmental organizations, and industry stakeholders. Recently, the Organisation for Economic Co-
operation and Development (OECD) developed several Integrated Approach to Testing and Assessment
(IATA) case studies demonstrating applicability of the weight of evidence framework (OECD. 2024).
As part of this weight of evidence approach, human health hazard profiles for DCHP were evaluated and
compared to profiles for five read-across chemicals, including DEHP, DBP, BBP, DINP, and DIDP
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(also referred to as "read-across phthalates" in this document). Overall, based on the weight of scientific
evidence, EPA has preliminarily concluded that the non-cancer POD for DCHP based on effects on the
developing male reproductive system consistent with a disruption of androgen action and phthalate
syndrome that was selected for characterizing risk from acute, intermediate, and chronic exposure to
DCHP is appropriate for use in human health risk assessment and is protective of human health,
including for PESS. Furthermore, EPA preliminarily concludes that potential carcinogenicity of DCHP
is not a significant remaining source of uncertainty in the quantitative and qualitative risk
characterization, despite the lack of carcinogenicity bioassays for DCHP. Further, these preliminary
conclusions are based on several key weight of scientific evidence considerations.
First, DCHP is toxicologically similar to DEHP, DBP, BBP, DINP, and DIBP and can induce
antiandrogenic effects and disrupt fetal testicular testosterone biosynthesis in rats leading to a spectrum
of effects on the developing male reproductive system consistent with phthalate syndrome. Second, for
the five read-across phthalates, effects on the developing male reproductive system consistent with
phthalate syndrome was the most sensitive and robust endpoint for deriving PODs for use in
characterizing risk for acute, intermediate, and chronic exposure scenarios. The only exception to this
was for DINP, in which chronic non-cancer liver effects were identified as a more sensitive outcome
than developmental toxicity for deriving a chronic POD. Finally, although cancer classifications for the
five read-across phthalates vary, in no case was cancer found to be a risk driver.
4.3 Human Health Risk Characterization
4.3.1 Risk Assessment Approach
The exposure scenarios, populations of interest, and toxicological endpoints used for evaluating risks
from acute, short-term/intermediate, and chronic/lifetime exposures are summarized in Table 4-13.
Table 4-13. Exposure Scenarios, Populations of Interest, and Hazard Values
Population of Interest
and Exposure Scenario
Workers
Male and female adolescents and adults (16+ years) and women of reproductive age directly
working with DCHP under light activity (breathing rate of 1.25 m3/h) (for further details see
(U.S. EPA. 2024a))
Exposure Durations
• Acute - 8 hours for a single workday
• Intermediate - 8 hours per workday for 22 days per 30-day period
• Chronic - 8 hours per workday for 250 days per year for 31 or 40 working years
Exposure Routes
• Inhalation and dermal
Occupational Non-users
Male and female adolescents and adults (16+ years old) indirectly exposed to DCHP within the
same work area as workers (breathine rate of 1.25 m3/h) (for further details see (U.S. EPA.
2024q))
Exposure Durations
• Acute, Intermediate, and Chronic - same as workers
Exposure Routes
• Inhalation, dermal (mist and dust deposited on surfaces)
Consumers
Male and female infants (<1 year), toddlers (1-2 years), children (3-5 years and 6-10 years),
young teens (11-15 years), teenagers (16-20 years) and adults (21+ years) exposed to DCHP
throueh product or article use (for further details see (U.S. EPA. 2024c))
Exposure Durations
• Acute - 1 day exposure
• Intermediate - 30 days per year
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Population of Interest
and Exposure Scenario
• Chronic - 365 days per year
Exposure Routes
• Inhalation, dermal, and oral
Bystanders
Male and female infants (<1 year), toddlers (1-2 years), and children (3-5 years and 6-10 years)
incidentally exposed to DCHP through product use (for further details see (U.S. EPA. 2024c))
Exposure Durations
• Acute - 1 day exposure
• Intermediate - 30 days per year
• Chronic - 365 days per year
Exposure Routes
• Inhalation
General Population
Male and female infants, children, youth, and adults exposed to DCHP through drinking water,
surface water, ambient air. and fish ingestion (for further details see (U.S. EPA. 2024d))
Exposure Durations
• Acute - Exposed to DCHP continuously for a 24-hour period
• Chronic - Exposed to DCHP continuously for up to 78 years
Exposure Routes
• Inhalation, dermal, and oral (depending on exposure scenario)
National Population
Children aged 3-5, 6-11 years, and 11 to <16 years; male and female adults 16+ years; and
women of reproductive age (16-49 years of age) exposed to DEHP, DBP, BBP, DIBP, and DINP
through all exposure pathways and routes as measured through urinary biomonitoring (i.e.,
NHANES) (for further details see (U.S. EPA. 2024ah))
Exposure Durations
• Durations not easily characterized in urinary biomonitoring studies
• Likely between acute and intermediate as phthalates have elimination half-lives on the
order of several hours and are quickly excreted from the body in urine. Spot urine samples,
as collected through NHANES, are representative of relatively recent exposures.
Exposure Routes
• NHANES urinary biomonitoring data provides an estimate of aggregate exposure (i.e.,
exposure through oral, inhalation, and dermal routes)
Health Effects,
Concentration and
Time Duration
Non-cancer Acute/Intermediate/Chronic Value
Sensitive health effect: Developmental toxicity (i.e., effects on the developing male reproductive
system including decreased fetal testicular testosterone; decreased AGD; Leydig cell effects;
decreased mRNA and/or protein expression of steroidogenic genes; decreased protein expression
of INSL3) (forfurther details see (U.S. EPA. 2024v))
HEC Daily, continuous = 13 mg/m3 (0.95 ppm)
HED Daily = 2.4 mg/kg-day; dermal and oral
Total UF (benchmark MOE) = 30 (UFA = 3; UFH = 10)
Hazard Relative Potency
Relative potency factors for DEHP, DBP, BBP, DIBP, DCHP, and DINP were derived based on
reduced fetal testicular testosterone. DBP was selected as the index chemical (for further details
see (U.S. EPA. 2024ah)).
RPFdehp= 0.84
RPFdbp = 1 (index chemical)
RPFbbp = 0.52
RPFdibp = 053
RPFdchp = 1.66
RPFdinp = 0.21
Index chemical (DBP) POD = HED Daily = 2.1 mg/kg-day
Total UF (benchmark MOE) = 30 (UFA = 3; UFH =10)
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4.3.1.1 Estimation of Non-cancer Risks from Exposure to DCHP
EPA used a margin of exposure (MOE) approach to identify potential non-cancer risks for individual
exposure routes (i.e., oral, dermal, inhalation). The MOE is the ratio of the non-cancer POD divided by a
human exposure dose. Acute, short-term, and chronic MOEs for non-cancer inhalation and dermal risks
were calculated using Equation 4-1.
Equation 4-1. Margin of Exposure Calculation
Non — cancer Hazard Value (POD)
M0E= Human Exposure
Where:
MOE
Non-cancer Hazard Value (POD) =
Raman Exposure =
Margin of exposure for acute, intermediate, or
chronic risk comparison (unitless)
HEC (mg/m3) or HED (mg/kg-day)
Exposure estimate (mg/m3 or mg/kg-day)
MOE risk estimates may be interpreted in relation to benchmark MOEs. Benchmark MOEs are typically
the total UF for each non-cancer POD. The MOE estimate is interpreted as a human health risk of
concern if the MOE estimate is less than the benchmark MOE (i.e., the total UF). On the other hand, if
the MOE estimate is equal to or exceeds the benchmark MOE, the risk is not considered to be of concern
and mitigation is not needed. Typically, the larger the MOE, the more unlikely it is that a non-cancer
adverse effect occurs relative to the benchmark. When determining whether a chemical substance
presents unreasonable risk to human health or the environment, calculated risk estimates are not "bright-
line" indicators of unreasonable risk, and EPA has the discretion to consider other risk-related factors in
addition to risks identified in the risk characterization.
4.3.1.2 Estimation of Non-cancer Aggregate Risks from Exposure to DCHP
As described in Section 4.1.5, EPA considered aggregate risk from exposure to DCHP across all routes
of exposure for each individual consumer and occupational COU evaluated for acute, intermediate, and
chronic exposure durations. To identify potential non-cancer risks for aggregate exposure scenarios for
workers (Section 4.3.2) and consumers (Section 4.3.3), EPA used the total MOE approach (U.S. EPA.
2001). For the total MOE approach, MOEs for each exposure route of interest in the aggregate scenario
must first be calculated. The total MOE for the aggregate scenario can then be calculated using Equation
4-2.
Equation 4-2. Total Margin of Exposure Calculation
1
Total MOE = jjj
MOE0rai MOEDermai MOEInhaiation
Where:
Total MOE
M^OEoral
M^OEDermal
MOlUnhalallon
Margin of exposure for aggregate scenario (unitless)
Margin of exposure for oral route (unitless)
Margin of exposure for dermal route (unitless)
Margin of exposure for inhalation route (unitless)
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Total MOE risk estimates may be interpreted in relation to benchmark MOEs, as described in Section
4.3.1.1.
4.3.2 Risk Estimates for Workers
This section summarizes risk estimates for workers from inhalation and dermal exposures, as well as
aggregated exposures to DCHP from individual DCHP COUs across routes. In this section, risks are
calculated for all exposed workers based on the DCHP-derived PODs described in Section 4.2.2.
Subsequently in Section 4.4.4, those same risks for female workers of reproductive age exposed to
DCHP at the highest levels (acute durations) are calculated using the more robust RPFs described in
Section 4.4.1 and added to estimates of national non-attributable exposure of five toxicologically similar
phthalates for an estimate of cumulative risk.
Risk estimates for workers from inhalation and dermal exposures, as well as aggregated exposures, are
shown in Table 4-14. This section provides discussion and characterization of risk estimates for workers,
including women of reproductive age and ONUs, for the various OESs and COUs.
Manufacturing
For the manufacture of DCHP, inhalation exposure from dust generation is expected to be the dominant
route of exposure. MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from
3.5 to 5.6 for average adult workers and women of reproductive age, while high-end dermal MOEs for
the same populations and exposure scenarios ranged from 532 to 845 (Benchmark = 30). The central
tendency MOEs for the same populations and exposure scenarios ranged from 36 to 58 for inhalation
exposure and 1,064 to 1,689 for dermal exposure (Benchmark = 30). Aggregation of inhalation and
dermal exposures led to negligible differences in risk when compared to risk estimates from inhalation
exposure alone. The variations between the central tendency and high-end estimates of worker
inhalation exposures are described below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 325 (Chemical Manufacturing). EPA multiplied these dust concentrations by the industry provided
maximum DCHP concentration manufactured (i.e., 100%) to estimate DCHP particulate concentrations
in the air. Therefore, the differences in the central tendency and high-end dust concentrations led to
significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the chemicals industry, the composition of workplace dust is uncertain. The
exposure and risk estimates are based on the assumption that the concentration of DCHP in workplace
dust is the same as the concentration of DCHP manufactured. However, it is likely that workplace dust
contains a variety of constituents that do not contain any DCHP in addition to particles from
manufactured DCHP. The constituents that do not contain DCHP would dilute the overall concentration
of DCHP in the dust, and the concentration of DCHP in workplace dust is likely less than the
concentration of DCHP in the final product. Due to this uncertainty in DCHP concentration in
workplace dust, central tendency values of exposure are expected to be most reflective of worker
exposures within the COUs covered under the "Manufacturing" OES (i.e., Manufacturing COU:
Domestic manufacturing).
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Import and Repackaging
For the import of DCHP, inhalation exposure from dust generation is expected to be the dominant route
of exposure. MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from 5.8 to
9.3 for average adult workers and women of reproductive age, while high-end dermal MOEs for the
same populations and exposure scenarios ranged from 532 to 845 (Benchmark = 30). The central
tendency MOEs for the same populations and exposure scenarios ranged from 134 to 259 for inhalation
exposure and 1,064 to 2,031 for dermal exposure (Benchmark = 30). Aggregation of inhalation and
dermal exposures led to negligible differences in risk when compared to risk estimates from inhalation
exposure alone. The large variations between the central tendency and high-end estimates of worker
inhalation exposures are described below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 45 (Wholesale and Retail Trade). EPA multiplied these dust concentrations by the industry
provided maximum DCHP concentration imported (i.e., 100%) to estimate DCHP particulate
concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the wholesale and retail trade industry, the composition of workplace dust is
uncertain. The exposure and risk estimates are based on the assumption that the concentration of DCHP
in workplace dust is the same as the concentration of imported DCHP. However, it is likely that
workplace dust contains a variety of constituents that do not contain any DCHP in addition to particles
from imported DCHP. The constituents that do not contain DCHP would dilute the overall concentration
of DCHP in the dust, and the concentration of DCHP in workplace dust is likely less than the
concentration of DCHP in the imported product. Due to this uncertainty in DCHP concentration in
workplace dust, central tendency values of exposure are expected to be most reflective of worker
exposures within the COUs covered under the "Import and repackaging" OES (i.e., Manufacture COU:
Importing; Processing COU: Repackaging [e.g., laboratory chemicals]).
Incorporation into Adhesives and Sealants
For the incorporation of DCHP into adhesives and sealants, inhalation exposure from dust generation is
expected to be the dominant route of exposure. MOEs for high-end acute, intermediate, and chronic
inhalation exposure ranged from 3.5 to 5.6 for average adult workers and women of reproductive age,
while high-end dermal MOEs for the same populations and exposure scenarios ranged from 532 to 845
(Benchmark = 30). The central tendency MOEs for the same populations and exposure scenarios ranged
from 36 to 58 for inhalation exposure and 1,064 to 1,689 for dermal exposure (Benchmark = 30).
Aggregation of inhalation and dermal exposures led to negligible differences in risk when compared to
risk estimates from inhalation exposure alone. The variations between the central tendency and high-end
estimates of worker inhalation exposures are described below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total and Respirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Ccodes starting
with 325 (Chemical Manufacturing). EPA multiplied these dust concentrations by the industry provided
maximum potential DCHP concentration in the raw material (i.e., 100%) to estimate DCHP particulate
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concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the chemical manufacturing industry, the composition of workplace dust is
uncertain. The exposure and risk estimates are based on the assumption that the concentration of DCHP
in workplace dust is the same as the concentration of DCHP in the raw material. However, it is likely
that workplace dust contains a variety of constituents that do not contain any DCHP in addition to
particles from DCHP-containing raw materials. The constituents that do not contain DCHP would dilute
the overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is
likely less than the concentration of DCHP in the raw material. Due to this uncertainty in DCHP
concentration in workplace dust, central tendency values of exposure are expected to be most reflective
of worker exposures within the COUs covered under the "Incorporation into adhesives and sealants"
OES (i.e., Processing COUs: Plasticizer in adhesive manufacturing; Adhesive and sealant chemicals in
adhesive manufacturing; Stabilizing agent in adhesive manufacturing).
Incorporation into Paints and Coatings
For the incorporation of DCHP into paints and coatings, inhalation exposure from dust generation is
expected to be the dominant route of exposure. MOEs for high-end acute, intermediate, and chronic
inhalation exposure ranged from 3.5 to 5.6 for average adult workers and women of reproductive age,
while high-end dermal MOEs for the same populations and exposure scenarios ranged from 532 to 845
(Benchmark = 30). The central tendency MOEs for the same populations and exposure scenarios ranged
from 36 to 58 for inhalation exposure and 1,064 to 1,689 for dermal exposure (Benchmark = 30).
Aggregation of inhalation and dermal exposures led to negligible differences in risk when compared to
risk estimates from inhalation exposure alone. The variations between the central tendency and high-end
estimates of worker inhalation exposures are described below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 325 (Chemical Manufacturing). EPA multiplied these dust concentrations by the industry provided
maximum potential DCHP concentration in the raw material (i.e., 100%) to estimate DCHP particulate
concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the chemical manufacturing industry, the composition of workplace dust is
uncertain. The exposure and risk estimates are based on the assumption that the concentration of DCHP
in workplace dust is the same as the concentration of DCHP in the raw material. However, it is likely
that workplace dust contains a variety of constituents that do not contain any DCHP in addition to
particles from DCHP-containing raw materials. The constituents that do not contain DCHP would dilute
the overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is
likely less than the concentration of DCHP in the raw material. Due to this uncertainty in DCHP
concentration in workplace dust, central tendency values of exposure are expected to be most reflective
of worker exposures within the COUs covered under the "Incorporation into paints and coatings" OES
(i.e., Processing COUs: Plasticizer in paint and coating manufacturing; Stabilizing agent in paint and
coating manufacturing).
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Incorporation into Other Formulations, Mixtures, or Reaction Products Not Otherwise Specified
For the incorporation of DCHP into other formulations, mixtures, or reaction products not otherwise
specified, inhalation exposure from dust generation is expected to be the dominant route of exposure.
MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from 3.5 to 5.6 for
average adult workers and women of reproductive age, while high-end dermal MOEs for the same
populations and exposure scenarios ranged from 532 to 845 (Benchmark = 30). The central tendency
MOEs for the same populations and exposure scenarios ranged from 36 to 58 for inhalation exposure
and 1,064 to 1,689 for dermal exposure (Benchmark = 30). Aggregation of inhalation and dermal
exposures led to negligible differences in risk when compared to risk estimates from inhalation exposure
alone. The variations between the central tendency and high-end estimates of worker inhalation
exposures are described below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS codes starting
with 325 (Chemical Manufacturing). EPA multiplied these dust concentrations by the industry provided
maximum potential DCHP concentration in the raw material (i.e., 100%) to estimate DCHP particulate
concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the chemical manufacturing industry, the composition of workplace dust is
uncertain. The exposure and risk estimates are based on the assumption that the concentration of DCHP
in workplace dust is the same as the concentration of DCHP in the raw material. However, it is likely
that workplace dust contains a variety of constituents that do not contain any DCHP in addition to
particles from DCHP-containing raw materials. The constituents that do not contain DCHP would dilute
the overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is
likely less than the concentration of DCHP in the raw material. Due to this uncertainty in DCHP
concentration in workplace dust, central tendency values of exposure are expected to be most reflective
of worker exposures within the COUs covered under the "Incorporation into other formulations,
mixtures, or reaction products not Covered Elsewhere" OES (i.e., Processing COU: Stabilizing agent in
asphalt paving, roofing, and coating materials manufacturing).
PVC Plastics Compounding
For PVC plastics compounding, inhalation exposure from dust generation is expected to be the dominant
route of exposure. MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from
3.7 to 6.0 for average adult workers and women of reproductive age, while high-end dermal MOEs
ranged from 532 to 845 (Benchmark = 30). For central tendency, MOEs for the same population and
exposure scenarios ranged from 76 to 137 for inhalation exposure and 1,064 to 1,894 for dermal
exposures (Benchmark = 30). Aggregation of inhalation and dermal exposures led to negligible
differences in risk when compared to risk estimates from inhalation exposure alone. The reason for the
variation between high-end and central tendency estimates of worker inhalation exposures is described
below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total and Respirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
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with 326 (Plastics and Rubber Manufacturing). EPA multiplied these dust concentrations by the industry
provided maximum potential DCHP concentration in the raw additive material (i.e., 100%) to estimate
DCHP particulate concentrations in the air. Therefore, the differences in the central tendency and high-
end dust concentrations led to significant differences between the central tendency and high-end risk
estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the compounding industry, the composition of workplace dust is uncertain.
The exposure and risk estimates assume that the concentration of DCHP in workplace dust is the same
as the concentration of DCHP in the raw material. However, it is likely that workplace dust contains a
variety of constituents that do not contain any DCHP in addition to particles from DCHP-containing raw
materials. The constituents that do not contain DCHP would dilute the overall concentration of DCHP in
the dust, and the concentration of DCHP in workplace dust is likely less than the concentration of DCHP
in the raw material. Due to the uncertainty of DCHP concentrations in workplace dust, central tendency
values of exposure are expected to be most reflective of worker exposures within the COUs covered
under the "PVC plastics compounding" OES (i.e., Processing COUs: Plasticizer in plastic material and
resin manufacturing; Plastics product manufacturing; Stabilizing agent in plastics product
manufacturing).
Non-PVC Material Compounding
For non-PVC material compounding, inhalation exposure from dust generation is expected to be the
dominant route of exposure. MOEs for high-end acute, intermediate, and chronic inhalation exposure
ranged from 6.2 to 9.9 for average adult workers and women of reproductive age, while high-end dermal
MOEs ranged from 532 to 845 (Benchmark = 30). For central tendency, MOEs for the same population
and exposure scenarios ranged from 126 to 217 for inhalation exposure and 1,064 to 1,805 for dermal
exposures (Benchmark = 30). Aggregation of inhalation and dermal exposures led to negligible
differences in risk when compared to risk estimates from inhalation exposure alone. The reason for the
variation between high-end and central tendency estimates of worker inhalation exposures is described
below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 326 (Plastics and Rubber Manufacturing). EPA multiplied these dust concentrations by the industry
provided maximum potential DCHP concentration in the raw additive material (i.e., 60%) to estimate
DCHP particulate concentrations in the air. Therefore, the differences in the central tendency and high-
end dust concentrations led to significant differences between the central tendency and high-end risk
estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the compounding industry, the composition of workplace dust is uncertain.
The exposure and risk estimates assume that the concentration of DCHP in workplace dust is the same
as the concentration of DCHP in the raw material. However, it is likely that workplace dust contains a
variety of constituents that do not contain any DCHP in addition to particles from DCHP-containing raw
materials. The constituents that do not contain DCHP would dilute the overall concentration of DCHP in
the dust, and the concentration of DCHP in workplace dust is likely less than the concentration of DCHP
in the raw material. Due to the uncertainty of DCHP concentrations in workplace dust, central tendency
values of exposure are expected to be most reflective of worker exposures within the COUs covered
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under the "Non-PVC Material Compounding" OES {i.e., Processing COUs: Plasticizer in in plastic
material and resin manufacturing; Plastics product manufacturing; Rubber product manufacturing;
Stabilizing agent in plastics product manufacturing).
PVC Plastics Converting
For PVC plastics converting, inhalation exposure from dust generation is expected to be the dominant
route of exposure. MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from
8.2 to 13 for average adult workers and women of reproductive age, while high-end dermal MOEs
ranged from 532 to 845 (Benchmark = 30). For central tendency, MOEs for the same population and
exposure scenarios ranged from 168 to 309 for inhalation exposure and 1,064 to 1,929 for dermal
exposures (Benchmark = 30). Aggregation of inhalation and dermal exposures led to negligible
differences in risk when compared to risk estimates from inhalation exposure alone. The reason for the
variation between high-end and central tendency estimates of worker inhalation exposures is described
below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codesstarting
with 326 (Plastics and Rubber Manufacturing). EPA multiplied these dust concentrations by the industry
provided maximum potential DCHP concentration in PVC plastic (i.e., 45%) to estimate DCHP
particulate concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the converting industry, the composition of workplace dust is uncertain. The
exposure and risk estimates assume that the concentration of DCHP in workplace dust is the same as the
concentration of DCHP in the PVC plastic. However, it is likely that workplace dust contains a variety
of constituents that do not contain any DCHP in addition to particles from DCHP-containing PVC
plastics. The constituents that do not contain DCHP would dilute the overall concentration of DCHP in
the dust, and the concentration of DCHP in workplace dust is likely less than the concentration of DCHP
in the PVC plastic. Due to the uncertainty of DCHP concentrations in workplace dust, central tendency
values of exposure are expected to be most reflective of worker exposures within the COUs covered
under the "PVC plastics converting" OES (i.e., Processing COU: Plasticizer in plastics product
manufacturing).
Non-PVC Material Converting
For non-PVC material converting, inhalation exposure from dust generation is expected to be the
dominant route of exposure. MOEs for high-end acute, intermediate, and chronic inhalation exposure
ranged from 18 to 30 for average adult workers and women of reproductive age, while high-end dermal
MOEs ranged from 532 to 845 (Benchmark = 30). For central tendency, MOEs for the same population
and exposure scenarios ranged from 378 to 696 for inhalation exposure and 1,064 to 1,929 for dermal
exposures (Benchmark = 30). Aggregation of inhalation and dermal exposures led to negligible
differences in risk when compared to risk estimates from inhalation exposure alone. The reason for the
variation between high-end and central tendency estimates of worker inhalation exposures is described
below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total and Respirable Particulates Not Otherwise Regulated (PNOR) for
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dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 326 (Plastics and Rubber Manufacturing). EPA multiplied these dust concentrations by the industry
provided maximum potential DCHP concentration in non-PVC material (i.e., 20%) to estimate DCHP
particulate concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the converting industry, the composition of workplace dust is uncertain. The
exposure and risk estimates assume that the concentration of DCHP in workplace dust is the same as the
concentration of DCHP in the non-PVC material. However, it is likely that workplace dust contains a
variety of constituents that do not contain any DCHP in addition to particles from DCHP-containing
non-PVC materials. The constituents that do not contain DCHP would dilute the overall concentration of
DCHP in the dust, and the concentration of DCHP in workplace dust is likely less than the concentration
of DCHP in the non-PVC material. Due to the uncertainty of DCHP concentrations in workplace dust,
central tendency values of exposure are expected to be most reflective of worker exposures within the
COUs covered under the "Non-PVC Material Converting" OES (i.e., Processing COUs: Plasticizer in
plastics product manufacturing; Rubber product manufacturing).
Application of Adhesives and Sealants
The applications of adhesives and sealants were assessed for solid and liquid products containing
DCHP. The majority of DCHP-containing adhesive and sealant products identified exist in solid form
and inhalation exposure from dust generation is expected to be the dominant route of exposure for solid
adhesive and sealant products, though dermal exposures to solid adhesive and sealant products
containing DCHP were also considered. There were a few liquid adhesive and sealant products
containing DCHP identified; however, liquid adhesive and sealant products containing DCHP are
extremely viscous and are better classified as "paste-like" materials. The literature and product data do
not indicate the potential for spray coating of DCHP-containing adhesive and sealant products;
therefore, inhalation exposures from the use of liquid adhesive and sealant chemicals containing DCHP
are expected to be de minimis since there are no mists generated during use, and the vapor pressure of
DCHP is very low. Consequently, EPA assumed negligible inhalation exposure from the use of liquid
adhesive and sealant products containing DCHP and only assessed dermal exposures for liquid adhesive
and sealant use. Risk values associated with the use of liquid adhesive and sealant products containing
DCHP are covered under the "Application of adhesives and sealants - liquids" OES (i.e., Industrial
COUs: Adhesives and sealants (transportation equipment manufacturing; computer and electronic
product manufacturing) and Commercial COUs: Adhesives and sealants). See Appendix F of the Draft
Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate (DCHP)
(U.S. EPA, 2024q) for product details.
MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from 6.4 to 10 for
average adult workers and women of reproductive age, while high-end dermal MOEs ranged from 532
to 845 (Benchmark = 30). For central tendency, MOEs for the same population and exposure scenarios
ranged from 116 to 201 for inhalation exposure and 1,064 to 1,821 for dermal exposures (Benchmark =
30). For dust exposure from solid products, the aggregation of inhalation and dermal exposures led to
negligible differences in risk when compared to risk estimates from inhalation exposure alone. The use
of liquid adhesive and sealant products is not expected to produce an inhalation exposure and therefore
dermal exposure to the liquid is expected to be the dominant route of exposure. For liquid adhesive and
sealant products, the high-end and central tendency dermal MOEs ranged from 532 to 845 and 1,064 to
1,821, respectively (Benchmark = 30). The reason for the variation between high-end and central
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tendency estimates of inhalation exposure to dust and the rationale for not assessing inhalation data for
liquids is described below.
EPA estimated worker inhalation exposures to dust from solid products using the Generic Model for
Central Tendency and High-End Inhalation Exposure to Total and Respirable Particulates Not
Otherwise Regulated (PNOR) for dust exposures (U.S. EPA. 2021b). The application of adhesives and
sealants does not fall under a specific NAICS Code; therefore, EPA used the entire PNOR model data
set to estimate DCHP particulate concentrations in the air during the use of solid DCHP-containing
adhesive and sealant products. EPA determined the 50th and 95th percentiles of the surrogate dust
monitoring data and multiplied these dust concentrations by the maximum potential DCHP
concentration in solid adhesive and sealant products (i.e., 55%) to estimate DCHP particulate
concentrations in the air. Therefore, the differences in the central tendency and high-end dust
concentrations led to differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in a variety of industries, the composition of workplace dust is uncertain. The
exposure and risk estimates assume that the concentration of DCHP in workplace dust is the same as the
concentration of DCHP in the adhesive or sealant material. However, it is likely that workplace dust
contains a variety of constituents that do not contain any DCHP in addition to particles from solid
DCHP-containing adhesive and sealant products. The constituents that do not contain DCHP would
dilute the overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust
is likely less than the concentration of DCHP in solid adhesive and sealant products. Due to the
uncertainty of DCHP concentrations in workplace dust, central tendency values of exposure are
expected to be most reflective of worker exposures within the COUs covered under the "Application of
adhesives and sealants - solids" OES (i.e., Industrial COUs: Adhesives and sealants (Transportation
equipment manufacturing; Computer and electronic product manufacturing) and Commercial COUs:
Adhesives and sealants).
Application of Paints and Coatings
The applications of paints and coatings were assessed for solid and liquid products containing DCHP.
For the liquid and solid paint and coating products containing DCHP, inhalation exposure is expected to
be the dominant route of exposure. For liquids, inhalation exposure is expected to occur primarily from
mist during spray application of the product, and for solids, inhalation exposure is expected to primarily
occur from dust release of the solid product prior to mixing with other components. Therefore, EPA
distinguished exposure estimates between liquid spray and solid dust exposure from the application of
paint and coating products containing DCHP. MOEs for high-end acute, intermediate, and chronic
inhalation exposure from the liquid spray application scenario ranged from 2.0 to 3.2 for average adult
workers and women of reproductive age, while high-end dermal MOEs ranged from 532 to 845
(Benchmark = 30). For central tendency of the liquid spray application scenario, MOEs for the same
populations and exposure scenarios ranged from 41 to 66 for inhalation exposures and 1,064 to 1,689 for
dermal exposures (Benchmark = 30). MOEs for high-end acute, intermediate, and chronic inhalation
exposure from the solid dust scenario ranged from 3.5 to 5.7 for average adult workers and women of
reproductive age, while high-end dermal MOEs ranged from 532 to 845 (Benchmark = 30). For central
tendency of the solid dust scenario, MOEs for the same populations and exposure scenarios ranged from
62 to 100 for inhalation exposure and 1,064 to 1,689 for dermal exposure (Benchmark = 30).
Aggregation of inhalation and dermal exposures led to small differences in MOEs when compared to
MOE estimates from dominant exposure route alone.
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For the "Application of paint and coatings - liquids" exposure scenario, EPA relied on mist monitoring
data from the ESD on Coating Application via Spray-Painting in the Automotive Refinishing Industry
(OECD, 201 la), which showed that the central tendency (i.e., 50th percentile) of mist concentrations
from automotive refinishing was 3.38 mg/m3 and the high-end (i.e., 95th percentile) was 22.1 mg/m3.
These mist concentration data were derived from a variety of industrial and commercial automotive
refinishing scenarios (e.g., different gun types and booth configurations), but all scenarios considered in
the ESD commonly used the spray application of auto refinishing coatings. While the tasks evaluated for
mist concentrations varied in time, with the 95th percentile of spray times among tasks being 141
minutes, EPA assumed that these mist concentrations may be persistent in an environment where
spraying occurs throughout all or most of the workday. The more highly pressurized spray guns
generally lead to higher inhalation exposure levels, and less pressurized spray guns generally lead to
lower inhalation exposure levels. The same trend is expected for dermal exposure. Specifically, high-
pressure spray applications are more likely to lead to higher levels of dermal exposure, and low-pressure
spray guns are more likely to lead to lower levels of dermal exposure. However, there are a variety of
factors other than spray equipment type that affect exposure levels, such as spray booth ventilation
configuration, product concentration, and spray duration. High-end levels of exposure represent
scenarios where one or more factors are contributing to unusually elevated exposure levels, whereas
central tendency levels of exposure represent more typical levels of exposure for scenarios where there
are few factors contributing to increased exposure. There is uncertainty regarding the particular
combination of factors that would lead to high-end levels of exposure.
The range of exposure estimates shown in Table 4-14 for "Application of paints and coatings - liquids"
are potentially reflective of industrial or commercial operations where paints and coatings are applied
using spray methods (i.e., Industrial COU: Paints and coatings; and Commercial COU: Paints and
coatings). As described in the section above, EPA assumed that task-based mist concentrations may be
persistent throughout the entirety of a workday, which is realistic but on the conservative end of
expected exposure duration for spray coating scenarios. The central tendency estimates of the spray
application scenario represent the midpoint of available product concentrations and the mist
concentration from the 50th percentile of the data presented in the ESD on Coating Application via
Spray-Painting in the Automotive Refinishing Industry (OECD. 2011a). and these levels of exposure are
expected to be typical for standard working conditions where workers are spray applying paint and
coating products containing DCHP for up to 8 hours per day. However, it is noted that there are several
factors that affect exposure levels related to the spray application of paint and coating chemicals
including spray equipment type, spray booth ventilation configuration, product concentration, and spray
duration.
High-end levels of exposure may occur if one or more of these factors contribute to elevated levels of
exposure; however, there is uncertainty regarding the conditions associated with high-end exposures.
Because the high-end risk estimates are based on high-end mist concentration levels, high-end product
concentration, and high-end exposure duration, the high-end risk values presented in Table 4-14 for
"Application of paints and coatings - liquids" may overestimate exposures for typical working
conditions. However, EPA does expect high-pressure spray application of paint and coating products
containing DCHP based on the available product information. Specifically, EPA identified one product
(Carboline. 2019b) that is intended for high-pressure spray application and the concentration of DCHP
in the product is listed as up to 2.5 percent. For an 8-hour workday spent spraying with a paint/coating
product containing 2.5 percent DCHP, mist levels exceeding 12.8 mg/m3 (i.e., 91st percentile of the
distribution of mist monitoring data) would result in risk values below the benchmark MOE. Although
most worker exposures to DCHP through spray application of paints and coatings are expected to be
closer to the central tendency exposure values for this COU, a confluence of a subset of variables (e.g.,
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low ventilation, high-pressure spray, etc.) would result in risk below the benchmark. While most
workers are not expected to experience elevated exposures (i.e., greater than 90th percentile of mist
concentration data for an 8-hour period) on a daily basis, it is considered plausible and expected for such
exposures to occur in an acute one-day scenario.
For any liquid paint and coating products that are applied using non-spray methods (i.e., Industrial
COUs: Inks, toner, and colorant products [e.g., screen printing ink]; Cellulose film production; Paints
and coatings; and Commercial COUs: Inks, toner, and colorant products [e.g., screen printing ink];
Paints and coatings), inhalation exposures are expected to be de minimis because mists or dusts are not
generated during application and the vapor pressure of DCHP is extremely low at room temperature.
However, workers may be exposed through the dermal route under non-spray application scenarios.
Therefore, exposures associated with the non-spray application of liquid paint and coating products
containing DCHP are characterized by the range of dermal risk values only, which are shown in Table
4-16 for "Application of paints and coatings - liquids."
For the "Application of paints and coatings - solids" exposure scenario, EPA estimated worker
inhalation exposures to dust from solid products using the Generic Model for Central Tendency and
High-End Inhalation Exposure to Total and Respirable Particulates Not Otherwise Regulated (PNOR)
for dust exposures (U.S. EPA. 2021b). The application of paints and coatings does not fall under a
specific NAICS Code; therefore, EPA used the entire PNOR model data set to estimate DCHP
particulate concentrations in the air during the use of solid DCHP-containing paint and coating products.
EPA determined the 50th and 95th percentiles of the surrogate dust monitoring data and multiplied these
dust concentrations by the maximum potential DCHP concentration in the solid paint and coating
component (i.e., 100%) to estimate DCHP particulate concentrations in the air. Therefore, the
differences in the central tendency and high-end dust concentrations led to differences between the
central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in a variety of industries, the composition of workplace dust is uncertain. The
exposure and risk estimates assume that the concentration of DCHP in workplace dust is the same as the
concentration of DCHP in the solid paint and coating component. However, it is likely that workplace
dust contains a variety of constituents that do not contain any DCHP in addition to particles from solid
DCHP-containing paint and coating products. The constituents that do not contain DCHP would dilute
the overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is
likely less than the concentration of DCHP in solid paint and coating products. Due to the uncertainty of
DCHP concentrations in workplace dust, central tendency values of exposure are expected to be most
reflective of worker exposures within the COUs covered under the "Application of paints and coatings -
solids" OES (i.e., Industrial COUs: Inks, toner, and colorant products [e.g., screen printing ink];
Cellulose film production; Paints and coatings; and Commercial COUs: Inks, toner, and colorant
products [e.g., screen printing ink]; Paints and coatings).
Use of Laboratory Chemicals
The use of laboratory chemicals was assessed for solid and liquid products containing DCHP. Inhalation
exposure from dust generation is expected to be the dominant route of exposure for solid laboratory
chemicals. MOEs for high-end acute, intermediate, and chronic inhalation exposure ranged from 6.4 to
10 for average adult workers and women of reproductive age, while high-end dermal MOEs ranged from
532 to 845 (Benchmark = 30). For central tendency, MOEs for the same population and exposure
scenarios ranged from 91 to 157 for inhalation exposure and 1,064 to 1,797 for dermal exposures
(Benchmark = 30). For dust exposure, the aggregation of inhalation and dermal exposures led to
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negligible differences in risk when compared to risk estimates from inhalation exposure alone. The use
of liquid laboratory chemicals is not expected to produce an inhalation exposure and therefore dermal
exposure to the liquid is expected to be the dominant route of exposure. For liquid laboratory chemicals,
the high-end and central tendency dermal MOEs ranged from 532 to 845 and 1,064 to 1,797,
respectively (Benchmark = 30). The reason for the variation between high-end and central tendency
estimates of worker inhalation exposure to dust and the rational for not assessing inhalation data for
liquids is described below.
EPA assessed worker inhalation exposures to dust from solid laboratory chemicals. The literature and
product data do not indicate the potential for the generation of mists during the use of liquid lab
chemicals. Therefore, inhalation exposures from the use of liquid DCHP-containing lab chemicals
containing DCHP are expected to be de minimis because there are no mists generated during use and the
vapor pressure of DCHP is very low. Consequently, EPA assumed negligible inhalation exposure from
the use of liquid lab chemicals and only assessed dermal exposures for liquid laboratory chemical use.
EPA estimated worker inhalation exposures to dust from solid laboratory chemicals using the Generic
Model for Central Tendency and High-End Inhalation Exposure to Total and Respirable Particulates
Not Otherwise Regulated (PNOR) for dust exposures (U.S. EPA. 2021b). For inhalation exposure to
PNOR, EPA determined the 50th and 95th percentiles of the surrogate dust monitoring data taken from
facilities with NAICS Codes starting with 54 (Professional, Scientific, and Technical Services). EPA
determined the 50th and 95th percentiles of the surrogate dust monitoring data and multiplied these dust
concentrations by the industry provided maximum potential DCHP concentration in lab chemicals {i.e.,
100%) to estimate DCHP particulate concentrations in the air. Therefore, the differences in the central
tendency and high-end dust concentrations led to differences between the central tendency and high-end
risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the laboratory services industry, the composition of workplace dust is
uncertain. The exposure and risk estimates assume that the concentration of DCHP in workplace dust is
the same as the concentration of DCHP in the laboratory chemicals. However, it is likely that workplace
dust contains a variety of constituents that do not contain any DCHP in addition to particles from solid
DCHP-containing laboratory chemicals. The constituents that do not contain DCHP would dilute the
overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is likely
less than the concentration of DCHP in the solid laboratory chemicals. Due to the uncertainty of DCHP
concentrations in workplace dust, central tendency values of exposure are expected to be most reflective
of worker exposures within the COUs covered under the "Use of lab chemicals" OES (i.e., Commercial
COU: Laboratory chemical).
Fabrication or Use of Final Products or Articles
For fabrication or use of final products or articles, inhalation exposure from dust generation is expected
to be the dominant route of exposure. MOEs for high-end acute, intermediate, and chronic inhalation
exposure ranged from 21 to 35 for average adult workers and women of reproductive age, whereas high-
end dermal MOEs for the same populations and exposure scenarios ranged from 532 to 845 (Benchmark
= 30). For central tendency, MOEs for the same population and exposure scenarios ranged from 193 to
311 for inhalation exposure and 1,064 to 1,689 for dermal exposures (Benchmark = 30). Aggregation of
inhalation and dermal exposures led to negligible differences in risk when compared to risk estimates
from inhalation exposure alone. The variations between the central tendency and high-end estimates of
worker inhalation exposures are described below.
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EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total andRespirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 337 (Furniture and Related Product Manufacturing). EPA multiplied these dust concentrations by
the maximum DCHP concentration in PVC (i.e., 45%) to estimate DCHP particulate concentrations in
the air. Therefore, the differences in the central tendency and high-end dust concentrations led to
significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
worker may experience in the end use and fabrication industries, the composition of workplace dust is
uncertain. The exposure and risk estimates assume that the concentration of DCHP in workplace dust is
the same as the concentration of DCHP in the PVC material. However, it is likely that workplace dust
contains a variety of constituents that do not contain any DCHP in addition to particles from DCHP-
containing products or articles. The constituents that do not contain DCHP would dilute the overall
concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is likely less than
the concentration of DCHP in final products and articles. Due to the uncertainty of DCHP
concentrations in workplace dust, central tendency values of exposure are expected to be most reflective
of worker exposures within the COUs covered under the "Fabrication or use of final products or
articles" OES (i.e., Industrial COU: Plastic and rubber products not covered elsewhere in transportation
equipment manufacturing; and Commercial COUs: Building/construction materials not covered
elsewhere; Other articles with routine direct contact during normal use including rubber articles; Plastic
articles [hard]).
Recycling and Waste Handling, Treatment, and Disposal
The approaches for the Recycling OES and the Waste handling, treatment and disposal OES are
identical and therefore consolidated here. For both OESs, the inhalation exposure from dust generation
is expected to be the dominant route of exposure. MOEs for high-end acute, intermediate, and chronic
inhalation exposure ranged from 11 to 18 for average adult workers and women of reproductive age,
while high-end dermal MOEs for the same populations and exposure scenarios ranged from 532 to 845
(Benchmark = 30) for both OESs. The central tendency MOEs for the same populations and exposure
scenarios ranged from 161 to 291 for inhalation exposure and 1,064 to 1,894 for dermal exposure for
both OES (Benchmark = 30). Aggregation of inhalation and dermal exposures led to negligible
differences in risk when compared to risk estimates from inhalation exposure alone. The variations
between the central tendency and high-end estimates of worker inhalation exposures are described
below.
EPA estimated worker inhalation exposures using the Generic Model for Central Tendency and High-
End Inhalation Exposure to Total and Respirable Particulates Not Otherwise Regulated (PNOR) for
dust exposures (U.S. EPA. 2021b). For inhalation exposure to PNOR, EPA determined the 50th and
95th percentiles of the surrogate dust monitoring data taken from facilities with NAICS Codes starting
with 56 (Administrative and Support and Waste Management and Remediation Services). EPA
multiplied these dust concentrations by the industry provided maximum DCHP concentration in PVC
(i.e., 45%) to estimate DCHP particulate concentrations in the air. PVC concentration was used for this
estimate because it is expected to be the predominant type of waste containing DCHP that is recycled or
disposed of. Therefore, the differences in the central tendency and high-end dust concentrations led to
significant differences between the central tendency and high-end risk estimates.
Although the PNOR (i.e., dust) concentration data provides a reliable range of dust concentrations that a
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worker may experience in the recycling and disposal industry, the composition of workplace dust is
uncertain. The exposure and risk estimates are based on the assumption that the concentration of DCHP
in workplace dust is the same as the concentration of DCHP in PVC plastics. However, it is likely that
workplace dust contains a variety of constituents that do not contain any DCHP in addition to particles
from DCHP-containing products or articles. The constituents that do not contain DCHP would dilute the
overall concentration of DCHP in the dust, and the concentration of DCHP in workplace dust is likely
less than the concentration of DCHP in recycled or disposed products or articles. Therefore, central
tendency values of exposure are expected to be more reflective of worker exposures within the COUs
covered under the "Recycling" and the "Disposal" OESs (i.e., Processing COU: Recycling; and Disposal
COU: Disposal).
Distribution in Commerce
Distribution in commerce includes transporting DCHP or DCHP-containing products between work
sites or to final use sites as well as loading and unloading from transport vehicles. Individuals in
occupations that transport DCHP-containing products (e.g., truck drivers) or workers who load and
unload transport trucks may encounter DCHP or DCHP-containing products.
Although some worker activities (e.g., loading or unloading) associated with distribution in commerce
are similar to COUs such as manufacturing or import, it is expected that workers involved in distribution
in commerce spend less time exposed to DCHP than workers in manufacturing or import facilities since
only part of the workday is spent in an area with potential exposure. Therefore, occupational exposures
associated with the distribution in commerce COU are expected to be less than other COUs with similar
worker activities (i.e., manufacturing and import).
4.3.2.1 Overall Confidence in Worker Risk Estimates for Individual DCHP COUs
As described in Section 4.1.1.5, EPA has moderate confidence in the assessed occupational inhalation
and dermal exposures (Table 4-5) and robust confidence in the non-cancer POD selected to characterize
risk from acute, intermediate, and chronic duration exposures to DCHP (Section 4.2). Overall, the
Agency has moderate confidence in the risk estimates calculated for worker and ONU inhalation and
dermal exposure scenarios. Sources of uncertainty associated with the occupational COUs are discussed
above in Section 4.3.2.
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2513 Table 4-14. Occupational Aggregate Ris
i Summary Table for DCHP
Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Manufacturing -
Domestic
Manufacturing
Domestic
manufacturing
Manufacturing
Average
Adult
Worker
High-End
3.8
5.2
5.6
532
725
776
3.8
5.2
5.6
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
Women of
Reproductive
Age
High-End
3.5a
4.7
5.1
579 a
789
845
3.5a
4.7
5.0
Central
Tendency
36"
49
53
1,157"
1,578
1,689
35"
48
51
ONU
High-End
40
55
58
1,064
1,451
1,553
39
53
56
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
Manufacturing -
Importing
Importing
Import and
Average
Adult
Worker
High-End
64
8.7
9.3
532
725
776
6.3
8.6
9.2
Central
Tendency
148
201
259
1,064
1,451
1,867
130
111
228
Women of
Reproductive
Age
High-End
5.8"
7.9
8.5
579 a
789
845
5.7"
7.8
8.4
Processing -
Repackaging
Repackaging
(e.g., laboratory
chemicals)
repackaging
Central
Tendency
134 "
182
235
1,157"
1,578
2,031
120"
163
210
ONU
High-End
148
201
216
1,064
1,451
1,553
130
111
189
Central
Tendency
148
201
259
1,064
1,451
1,867
130
111
228
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Plasticizer in:
High-End
3.8
5.2
5.6
532
725
776
3.8
5.2
5.6
- adhesive
manufacturing
Average
Adult
Adhesive and
Central
40
55
58
1,064
1,451
1,553
39
53
56
Processing -
sealant
chemicals in:
Worker
Tendency
Processing -
incorporation
- adhesive
manufacturing
Incorporation
into adhesives
and sealants
into formulation,
mixture, or
Stabilizing
agent in:
- adhesive
Women of
High-End
3.5"
4.7
5.1
579 "
789
845
3.5"
4.7
5.0
reaction product
Reproductive
Age
Central
36"
49
53
1,157"
1,578
1,689
35"
48
51
manufacturing
Tendency
High-End
40
55
58
1,064
1,451
1,553
39
53
56
ONU
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
Plasticizer in:
High-End
3.8
5.2
5.6
532
725
776
3.8
5.2
5.6
- paint and
Processing -
coating
manufacturing
- printing ink
manufacturing
Average
Adult
Worker
Processing -
incorporation
into formulation,
mixture, or
Incorporation
into paints and
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
Stabilizing
coatings
Women of
High-End
3.5"
4.7
5.1
579"
789
845
3.5"
4.7
5.0
reaction product
agent in:
- Paint and
coating
manufacturing
Reproductive
Age
Central
Tendency
36"
49
53
1,157"
1,578
1,689
35"
48
51
High-End
40
55
58
1,064
1,451
1,553
39
53
56
ONU
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Processing -
Processing -
incorporation
into formulation,
mixture, or
reaction product
Stabilizing
agent in:
- asphalt
paving, roofing,
and coating
materials
manufacturing
Incorporation
into other
formulations,
mixtures, and
reaction
products not
covered
elsewhere
Average
Adult
Worker
High-End
3.8
5.2
5.6
532
725
776
3.8
5.2
5.6
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
Women of
Reproductive
Age
High-End
3.5 a
4.7
5.1
579 a
789
845
3.5a
4.7
5.0
Central
Tendency
36"
49
53
1,157"
1,578
1,689
35"
48
51
ONU
High-End
40
55
58
1,064
1,451
1,553
39
53
56
Central
Tendency
40
55
58
1,064
1,451
1,553
39
53
56
Processing -
Processing -
incorporation
into formulation,
mixture, or
reaction product
Plasticizer in:
- plastic
material and
resin
manufacturing
- plastics
product
manufacturing
PVC plastics
compounding
Average
Adult
Worker
High-End
4.1
5.6
6.0
532
725
776
4.1
5.5
5.9
Central
Tendency
83
114
137
1,064
1,451
1,741
77
106
127
Stabilizing
agent in:
- plastics
product
manufacturing
Women of
Reproductive
Age
High-End
3.7 a
5.0
5.4
579 a
789
845
3.7 a
5.0
5.4
Central
Tendency
76"
103
124
1,157"
1,578
1,894
71a
97
116
ONU
High-End
83
114
122
1,064
1,451
1,553
11
106
113
Central
Tendency
83
114
137
1,064
1,451
1,741
11
106
127
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Processing -
Processing -
incorporation
into article
Plasticizer in:
- Plastics
product
manufacturing
PVC plastics
converting
Average
Adult
Worker
High-End
9.1
12
13
532
725
776
8.9
12
13
Central
Tendency
186
253
309
1,064
1,451
1,773
158
215
263
Women of
Reproductive
Age
High-End
8.2"
11
12
579"
789
845
8.1"
11
12
Central
Tendency
168"
229
280
1,157"
1,578
1,929
147"
200
244
ONU
High-End
186
253
271
1,064
1,451
1,553
158
215
231
Central
Tendency
186
253
309
1,064
1,451
1,773
158
215
263
Processing -
Processing -
incorporation
into formulation,
mixture, or
reaction product
Plasticizer in:
- plastics
product
manufacturing
- rubber
product
manufacturing
- plastic
material and
resin
manufacturing
Non-PVC
material
compounding
Average
Adult
Worker
High-End
6.8
9.3
9.9
532
725
776
6.7
9.2
9.8
Central
Tendency
139
190
217
1,064
1,451
1,659
123
168
192
Women of
Reproductive
Age
High-End
6.2"
8.4
9.0
579"
789
845
6.1"
8.3
8.9
Stabilizing
agent in:
- Plastics
product
manufacturing
Central
Tendency
126"
172
196
1,157"
1,578
1,805
114"
155
177
ONU
High-End
139
190
203
1,064
1,451
1,553
123
168
180
Central
Tendency
139
190
217
1,064
1,451
1,659
123
168
198
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Processing -
Processing -
incorporation
into article
Plasticizer in:
- plastics
product
manufacturing
- rubber
product
manufacturing
Non-PVC
material
converting
Average
Adult
Worker
High-End
20
28
30
532
725
776
20
27
29
Central
Tendency
417
569
696
1,064
1,451
1,773
300
409
500
Women of
Reproductive
Age
High-End
18"
25
27
579"
789
845
18"
24
26
Central
Tendency
378"
515
630
1,157"
1,578
1,929
285"
388
475
ONU
High-End
417
569
609
1,064
1,451
1,553
300
409
438
Central
Tendency
417
569
696
1,064
1,451
1,773
300
409
500
Industrial Use -
Finishing agent
Cellulose film
production
Application of
paints and
coatings -
liquids
Average
Adult
Worker
High-End
2.2
3.0
3.2
532
725
776
2.2
2.9
3.2
Industrial Use -
Inks, toner, and
colorant
products
Inks, toner, and
colorant
products (e.g.,
screen printing
ink)
Central
Tendency
45
62
66
1,064
1,451
1,553
44
59
64
Women of
Reproductive
Age
High-End
2.0"
2.7
2.9
579"
789
845
2.0"
2.7
2.9
Commercial Use
- Inks, toner,
and colorant
products
Inks, toner, and
colorant
products (e.g.,
screen printing
ink)
Central
Tendency
41"
56
60
1,157"
1,578
1,689
40"
54
58
ONU
High-End
45
62
66
1,064
1,451
1,553
44
59
64
Industrial Use -
Paints and
coatings
Paints and
coatings
Central
Tendency
45
62
66
1,064
1,451
1,553
44
59
64
Commercial Use
- Paints and
coatings
Paints and
coatings
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Industrial Use -
Cellulose film
High-End
3.9
5.3
5.7
532
725
776
3.9
5.3
5.7
Finishing agent
production
Industrial Use -
Inks, toner, and
Average
Central
69
94
100
1,064
1,451
1,553
64
88
94
Inks, toner, and
colorant
colorant
products (e.g.,
Adult
Worker
Tendency
products
screen printing
ink)
Commercial Use
Inks, toner, and
Application of
High-End
3.5 a
4.8
5.2
579 a
789
845
3.5a
4.8
5.1
- Inks, toner,
and colorant
products
colorant
products (e.g.,
screen printing
ink)
paints and
coatings -
solids
Women of
Reproductive
Age
Central
Tendency
62"
85
91
1,157"
1,578
1,689
59"
80
86
Industrial Use -
Paints and
High-End
69
94
100
1,064
1,451
1,553
64
88
94
Paints and
coatings
coatings
ONU
Commercial Use
Paints and
Central
69
94
100
1,064
1,451
1,553
64
88
94
- Paints and
coatings
Tendency
coatings
Adhesives and
sealants (e.g.,
computer and
electronic
Average
High-End
N/A
N/A
N/A
532
725
776
532
725
776
Industrial Uses -
Adult
Worker
Central
Tendency
N/A
N/A
N/A
1,064
1,451
1,674
1,064
1,451
1,674
Adhesives and
product
High-End
N/A
N/A
N/A
579°
789
845
579 a
789
845
sealants
manufact.;
transportation
equipment
manufact.)
Application of
adhesives and
sealants -
liquids
Women of
Reproductive
Age
Central
N/A
N/A
N/A
1,157°
1,578
1,821
1,157"
1,578
1,821
Commercial
Tendency
uses -
Adhesives and
Adhesives and
sealants
ONU
High-End
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
sealants
Central
Tendency
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Industrial Uses -
Adhesives and
sealants
Adhesives and
sealants in -
computer and
electronic
product
manufact.;
transportation
equipment
manufact.
Application of
adhesives and
sealants -
solids
Average
Adult
Worker
High-End
7.1
9.7
10
532
725
776
7.0
9.6
10
Central
Tendency
128
175
201
1,064
1,451
1,674
114
156
180
Women of
Reproductive
Age
High-End
6.4 "
8.8
9.4
579"
789
845
6.4"
8.7
9.3
Commercial
Uses -
Adhesives and
sealants
Adhesives and
sealants
Central
Tendency
116"
158
182
1,157"
1,578
1,821
105"
144
166
ONU
High-End
128
175
187
1,064
1,451
1,553
114
156
167
Central
Tendency
128
175
201
1,064
1,451
1,674
114
156
180
Commercial Use
- Laboratory
chemicals
Laboratory
chemicals
Use of
laboratory
chemicals -
liquid
Average
Adult
Worker
High-End
N/A
N/A
N/A
532
725
776
532
725
776
Central
Tendency
N/A
N/A
N/A
1,064
1,451
1,652
1,064
1,451
1,652
Women of
Reproductive
Age
High-End
N/A
N/A
N/A
579a
789
845
579"
789
845
Central
Tendency
N/A
N/A
N/A
1,157"
1,578
1,797
1,157"
1,578
1,797
ONU
High-End
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Central
Tendency
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Commercial Use
- Laboratory
chemicals
Laboratory
chemicals
Use of
laboratory
chemicals -
solid
Average
Adult
Worker
High-End
7.1
9.7
10
532
725
776
7.0
9.6
10
Central
Tendency
101
138
157
1,064
1,451
1,652
92
126
143
Women of
Reproductive
Age
High-End
6.4 "
8.8
9.4
579"
789
845
6.4"
8.7
9.3
Central
Tendency
91 a
125
142
1,157"
1,578
1,797
85"
116
132
ONU
High-End
101
138
148
1,064
1,451
1,553
92
126
135
Central
Tendency
101
138
157
1,064
1,451
1,652
92
126
143
Industrial Use -
Other articles
with routine
direct contact
during normal
use including
rubber articles;
plastic articles
(hard)
Other articles
with routine
direct contact
during normal
use including
rubber articles;
plastic articles
(hard) (e.g.,
transportation
equipment
manufact.)
Fabrication or
use of final
products or
articles
Average
Adult
Worker
High-End
24
32
35
532
725
776
23
31
33
Central
Tendency
213
291
311
1,064
1,451
1,553
178
242
259
Women of
Reproductive
Age
High-End
21"
29
31
579"
789
845
21"
28
30
Commercial Use
- Building/
construction
materials not
covered
elsewhere
Building/
construction
materials not
covered
elsewhere
Central
Tendency
193"
263
282
1,157"
1,578
1,689
166"
226
242
Commercial Use
- Other articles
with routine
direct contact
during normal
use including
rubber articles
Other articles
with routine
direct contact
during normal
use including
rubber articles;
plastic articles
(hard)
ONU
High-End
213
291
311
1,064
1,451
1,553
178
242
259
Central
Tendency
213
291
311
1,064
1,451
1,553
178
242
259
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Life Cycle
Stage/ Category
Subcategory
OES
Worker
Population
Exposure
Level
Inhalation Risk Estimates
(Benchmark MOE = 30)
Dermal Risk Estimates
(Benchmark MOE = 30)
Aggregate Risk Estimates
(Benchmark MOE = 30)
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Acute
Intermed.
Chronic
Processing -
Recycling
Recycling
Recycling
Average
Adult
Worker
High-End
12
17
18
532
725
776
12
16
17
Central
Tendency
178
242
291
1,064
1,451
1,741
152
208
249
Women of
Reproductive
Age
High-End
11"
15
16
579"
789
845
11"
15
16
Central
Tendency
161"
219
263
1,157"
1,578
1,894
141"
193
231
ONU
High-End
178
242
260
1,064
1,451
1,553
152
208
222
Central
Tendency
178
242
291
1,064
1,451
1,741
152
208
249
Disposal -
Disposal
Disposal
Waste
handling,
treatment and
disposal
Average
Adult
Worker
High-End
12
17
18
532
725
776
12
16
17
Central
Tendency
178
242
291
1,064
1,451
1,741
152
208
249
Women of
Reproductive
Age
High-End
11"
15
16
579 a
789
845
11"
15
16
Central
Tendency
161 a
219
263
1,157"
1,578
1,894
141"
193
231
ONU
High-End
178
242
260
1,064
1,451
1,553
152
208
222
Central
Tendency
178
242
291
1,064
1,451
1,741
152
208
249
" Scaling by the RPF and application of the index chemical POD provides a more sensitive and robust hazard assessment than the DCHP-specific POD, given its more
limited toxicological data set. Please see Table 4-22 for the RPF analysis values.
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4.3.3 Risk Estimates for Consumers
This section summarizes risk estimates for consumers from inhalation, ingestion, and dermal exposures,
as well as aggregated exposures, to DCHP from individual DCHP COUs across routes. In this section,
risks are calculated for all exposed populations based on the DCHP-derived PODs described in Section
4.2.2. Subsequently in Section 4.4.5, those same risks for consumers that are adults of reproductive age,
infants, children, and teenagers exposed to DCHP at the highest levels (acute durations) are calculated
using the more robust RPFs described in Section 4.4.1 and added to estimates of national non-
attributable exposure of five toxicologically similar phthalates for an estimate of cumulative risk.
Table 4-15 summarizes the dermal, inhalation, ingestion, and aggregate MOEs used to characterize non-
cancer risk for acute, intermediate, and chronic exposure to DCHP and presents these values for all
lifestages for each COU. A screening-level assessment for consumers considers high-intensity exposure
scenarios which rely on conservative assumptions to assess exposures that would be expected to be on
the high end of the expected exposure distribution. The corresponding high-intensity exposure scenario
risk estimates are used as a conservative and health protective screening approach. MOEs for high-
intensity exposure scenarios are shown for all consumer COUs, while MOEs for medium-intensity
exposure scenarios are shown only for COUs with high-intensity MOEs close to the benchmark of 30
(no scenarios were in exceedance or within 20% of the benchmark). Exposure risk estimates were
calculated considering product and article user and bystander. Bystanders are people that are not in
direct use or application of a product but can be exposed to DCHP by proximity to the use of the product
via inhalation of gas-phase emissions or suspended dust. Some product scenarios were assessed for
children under 10 years as bystanders and children older than 11 years as users, because the products
were not targeted for direct use by young children (<10 years). In instances where a lifestage could
reasonably be either a product user or bystander, the inputs for a user were selected because that
scenario would result in larger exposure doses.
Of note, the risk summary below is based on the most sensitive non-cancer endpoint for all relevant
duration scenarios (i.e., developmental toxicity for acute, intermediate, and chronic durations). MOEs
for all high-, medium- and low-intensity exposure scenarios for all COUs are provided in the Draft
Consumer Risk Calculator for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024e).
COUs with MOEs for High-Intensity Exposure Scenarios Ranging from 740 to 950,000
All consumer COUs product and article examples resulted in MOEs for high-intensity exposure
scenarios ranging from 740 for acute duration dermal exposure to DCHP from outdoor seating for
infants (less than one year old) to 950,000 for intermediate duration inhalation of suspended dust from
automotive adhesives for adults (21+ years) (Table 4-15). Variability in MOEs for these high-intensity
exposure scenarios results from use of different exposure factors for each COU and product or article
example that led to different estimates of exposure to DCHP. As described in the Draft Consumer and
Indoor Dust Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024c) and Draft
Non-Cancer Human Health Hazard Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024v).
EPA has moderate to robust confidence in the exposure estimates and robust confidence in the non-
cancer hazard value used to estimate non-cancer risk for these COUs.
Adhesives and Sealants
Two different scenarios were assessed under this COU for products with differing use patterns for
example, adhesives for small repairs (2 products) and automotive adhesives (2 products). The two
scenarios capture the variability in product formulation and use patterns in the high, medium, and low
intensity use estimates. The small repairs products are used in small amounts and have very short
working times (<5 minutes), which limits the potential for inhalation exposure. However, if dermal
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exposure occurs during use it is possible that the product may not be washed off immediately, resulting
in exposure. As such, both products were modeled for dermal exposure only. The automotive adhesives
products may be used for large repairs to vehicle bodies and were assessed for both inhalation and
dermal exposure. The overall confidence in the inhalation exposure estimates for this COU is robust
because the CEM default parameters are representative and plausible use patterns and location of use.
For dermal exposure, EPA used a dermal flux approach. The Agency has moderate confidence in dermal
estimates because of the moderate uncertainty in the partitioning from product to skin. In addition,
subsequent dermal absorption is not well characterized or confirmed with experimental results.
However, other parameters such as frequency and duration of use, and surface area in contact, are well
understood and representative, resulting in an overall confidence of moderate in a health protective
estimate. Additionally, EPA has robust overall confidence in the underlying chronic POD based on
developmental toxicity (Section 4.2).
Aggregate risk from dermal, ingestion, and inhalation exposures to DCHP for the two scenarios was also
considered. All three exposure routes are essentially negligible in their overall contribution to the
aggregate since the individual MOE values were significantly higher than the benchmark of 30.
Other Articles with Routine Direct Contact During Normal Use Including Rubber Articles; Plastic
Articles (Hard)
One scenario was assessed under this COU. It considered multiple articles and routine dermal contact
with similar use patterns. The scenario for small articles of routine dermal contact was assessed for
dermal exposures only because inhalation and ingestion would have low exposure potential due to the
small surface area of the articles and limited time spent in an indoor environment before disposal and
mouthing was not an expected behavior based on the generic article examples identified.
The small articles with the potential for semi-routine contact scenario considers some generic example
descriptions but not specific products, for example labels, nitrocellulose; ethylcellulose; chlorinated
rubber; PVAc; PVC. These examples are expected to be used in smaller items and the primary exposure
route is through dermal contact when handling the goods. Although DCHP content was not reported or
measured in specific products, this scenario was included for dermal exposure calculations, which does
not use weight fractions. Dermal contact events are likely short and/or infrequent, but an individual
could have appreciable daily contact with multiple items. All acute and chronic MOE values were well
above the benchmark of 30. The MOE values increase with increasing age due to changes in inhalation
rate to body weight ratios, thus leading to decreasing exposure with increasing age.
Dermal absorption estimates are based on the assumption that dermal absorption of DCHP from solid
objects would be limited by aqueous solubility of DCHP. EPA has slight confidence for solid objects
because the high uncertainty in the assumption of partitioning from solid to liquid and subsequent
dermal absorption is not well characterized. However, other parameters such as frequency and duration
of use, and surface area in contact, are well understood and representative, resulting in an overall
confidence of moderate in a health protective estimate. Additionally, EPA has robust overall confidence
in the underlying chronic POD based on developmental toxicity (Section 4.2).
Other; Consumer Articles that Contain Dicyclohexyl Phthalate from: Inks, Toner, and Colorant,
Paints and Coatings, Adhesives, and Sealants (e.g., Paper Products, Textiles, Products Using
Cellulose Film, etc.)
Three different scenarios were assessed under this COU for articles with differing use patterns: Outdoor
seating, small articles with potential for routine contact (multiple non-specific articles), and electronics
containing dye adhesive (qualitative discussion). The outdoor seating and small articles scenarios were
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assessed for dermal exposures only. For the outside seating scenario, based on DCHP's waterproofing
and weather resistant properties and the expected use case for outdoor seating, EPA anticipated use of
this article occurs outdoors where air exchange rates are large; thus, inhalation exposure is expected to
be negligible. Dermal exposures were modeled for a scenario where consumers sit on coated surfaces
(e.g., on seats at a sporting event or directly on a terrace). The small articles with the potential for semi-
routine contact scenario considers generic examples but no specific items were identified (like labels for
cleaning products or arts and crafts materials); instead, EPA used article descriptors like labels and
packaging adhesives, foil and cellophane lacquers, and printing inks. These articles are expected to be
used in small quantities and the primary exposure route is through dermal contact when handling the
goods. Although DCHP content was not reported or measured in specific articles, this scenario was
included for dermal exposure calculations that do not use weight fractions. Dermal contact events are
likely short and/or infrequent, but an individual could have appreciable daily contact with multiple
items. The items are not expected to be mouthed and the likelihood of inhalation exposure is minimal
due to their small surface area and limited time spent in an indoor environment before disposal. The
electronics containing dye adhesive was qualitatively assessed because it is used in small quantities and
contained within the electronic articles; thus, no exposures are expected during potential use of these
items. An aggregate analysis for this COU was not performed because all scenarios were assessed for
dermal exposures only.
EPA has slight confidence in some aspects of the exposure estimate for solid articles because of the high
uncertainty in the assumption of partitioning from solid to liquid and because subsequent dermal
absorption is not well characterized. However, other parameters such as frequency and duration of use
and surface area in contact are well understood and representative, resulting in an overall confidence of
moderate in a health protective estimate. Additionally, EPA has robust overall confidence in the
underlying chronic POD based on developmental toxicity (Section 4.2).
4.3.3.1 Overall Confidence in Consumer Risks
As described in Section 4.1.2.3 and in more detail in the Draft Consumer and Indoor Dust Exposure
AssessmentDicyclohexylPhthalate (DCHP) (U.S. EPA. 2024c). EPA has moderate and robust
confidence in the assessed inhalation, ingestion, and dermal consumer exposure scenarios, and robust
confidence in the acute, intermediate and chronic non-cancer PODs selected to characterize risk from
acute, intermediate, and chronic duration exposures to DCHP (see Section 4.2 and (U.S. EPA. 2024c)).
The exposure doses used to estimate risk relied on conservative, health protective inputs and parameters
that are considered representative of a wide selection of use patterns. Sources of uncertainty associated
with all consumer COUs are discussed above in Section 4.3.3.
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2646 Table 4-15. Consumer Risk Summary Table
Life Cycle Stage:
COU: Subcategory
Product or Article
Duration
Exposure
Route
Exposure
Scenario
(H, M, L) a
Lifestage (years)
(Benchmark MOE = 30)
Infant
(<1 year)
Toddler
(1-2 years)
Preschooler
(3-5 years)
Middle
Childhood
(6-10 years)
Young
Teen
(11-15 years)
Teenagers
(16-20 years)
Adult
(21+ years)
Consumer Uses:
Adhesives and
sealants: Adhesives
and sealants
Adhesives tor small
repairs
Acute c
Dermal
H
-
-
-
-
16,000
17,000
16,000
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
-
-
-
-
16,000
17,000
16,000
Intermed.
-
-
-
-
-
-
-
-
-
Chronic
Dermal
H
-
-
-
-
110,000
120,000
110,000
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
-
-
-
-
110,000
120,000
110,000
Consumer Uses:
Adhesives and
sealants: Adhesives
and sealants
Automotive
adhesives
('b = MOE for
bystander scenario)
Acute c
Dermal
H
-
-
-
-
11,000
12,000
11,000
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
20,000 b
21,000 b
26,000 b
37,000 b
43,000
52,000
63,000
Aggregate
H
20,000 b
21,000 b
26,000 b
37,000 b
8,800
9,800
9,600
Intermed.
Dermal
H
-
-
-
-
170,000
180,000
170,000
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
300,000 6
310,000 6
390,000 6
560,000 b
650,000
780,000
950,000
Aggregate
H
300,000 6
310,000 6
390,000 6
560,000 b
130,000
150,000
140,000
Chronic
-
-
-
-
-
-
-
-
-
Consumer Uses:
Other articles with
routine direct contact
during normal use
including rubber
articles; plastic
articles (hard)
Small articles with
potential for semi-
routine contact:
labels,
nitrocellulose;
ethylcellulose;
chlorinated rubber;
PVAc; PVC
Acute c
Dermal
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Intermed.
-
-
-
-
-
-
-
-
-
Chronic
Dermal
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
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Life Cycle Stage:
COU: Subcategory
Product or Article
Duration
Exposure
Route
Exposure
Scenario
(H, M, L) a
Lifestage (years)
(Benchmark MOE = 30)
Infant
(<1 year)
Toddler
(1-2 years)
Preschooler
(3-5 years)
Middle
Childhood
(6-10 years)
Young
Teen
(11-15 years)
Teenagers
(16-20 years)
Adult
(21+ years)
Consumer Uses:
Consumer articles
that contain
dicyclohexyl
phthalate from: Inks,
toner, and colorants;
Paints and coatings;
Adhesives and
sealants (e.g., paper
products, textiles,
products using
cellulose film, etc.)
Outdoor seating
Acute c
Dermal
H
740
870
1,000
1,200
1,600
1,700
1,600
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
740
870
1,000
1,200
1,600
1,700
1,600
Intermed.
-
-
-
-
-
-
-
-
-
Chronic
Dermal
H
5,200
6,100
7,000
8,700
11,000
12,000
11,000
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
5,200
6,100
7,000
8,700
11,000
12,000
11,000
Consumer Uses:
Consumer articles
that contain
dicyclohexyl
phthalate from: Inks,
toner, and colorants;
Paints and coatings;
Adhesives and
sealants (e.g., paper
products, textiles,
products using
cellulose film, etc.)
Small articles with
the potential for
semi-routine
contact: labels, and
packaging
adhesives, foil and
cellophane lacquers,
and printing inks
Acutec
Dermal
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Intermed.
-
-
-
-
-
-
-
-
-
Chronic
Dermal
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Ingestion
H
-
-
-
-
-
-
-
Inhalation
H
-
-
-
-
-
-
-
Aggregate
H
2,100
2,400
2,800
3,500
4,400
4,900
4,500
Consumer Uses:
Consumer articles
that contain
dicyclohexyl
phthalate from: Inks,
toner, and colorants;
Paints and coatings;
Adhesives and
sealants (e.g., paper
products, textiles,
products using
cellulose film, etc.)
Electronics
containing dye
adhesive
Exposures not expected. Identified in dye attach adhesive used in wirebond packaging for semiconductor devices or in automotive cameras. As the
adhesive is used in small quantities and contained within the electronic articles, no exposures are expected during potential use of these items
"Exposure scenario intensities include high (H), medium (M), and low (L).
4 Bystander scenarios
c Scaling by the RPF and application of the index chemical POD provides a more sensitive and robust hazard assessment than the DCHP-specific POD, given its more limited toxicological data
set. Please see Table 4-23 for the RPF analysis values.
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4,3.4 Risk Estimates for General Population Exposed to DCHP through Environmental
Releases
As described in the Draft Environmental Media, General Population, and Environmental Exposure
Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024p) and Section 4.1.3, EPA used a
screening-level approach for general population exposures for DCHP releases associated with TSCA
COUs. Fenceline communities were considered as part of the general population in proximity to
releasing facilities as part of the ambient air exposure assessment by utilizing pre-screening
methodology described in EPA's Draft TSCA Screening Level Approach for Assessing Ambient Air and
Water Exposures to Fenceline Communities (Version 1.0) (U.S. EPA. 2022b). For other exposure
pathways, the Agency's screening method assessing high-end exposure scenarios used release data that
reflect exposures expected to occur in proximity to releasing facilities, which would include fenceline
communities.
EPA evaluated surface water, drinking water, fish ingestion, and ambient air pathways quantitatively, in
addition to the land pathway (i.e., landfills and application of biosolids) qualitatively. For pathways
assessed quantitatively, high-end estimates of DCHP concentration in the various environmental media
were used for screening-level purposes. EPA used an MOE approach using high-end exposure estimates
to determine whether an exposure pathway had potential non-cancer risks. High-end exposure estimates
were defined as those associated with the industrial and commercial releases from a COU and OES that
resulted in the highest environmental media concentrations. If there is no risk for an individual identified
as having the potential for the highest exposure associated with a COU for a given pathway of exposure,
then that pathway was determined to not be a pathway of concern and not pursued further. If any
pathways were identified as a pathway of concern for the general population, further exposure
assessments for that pathway would be conducted to include higher tiers of modeling when available
and exposure estimates developed for additional subpopulations and COUs. Using a screening-level
approach described in Section 4.1.3, no pathways of exposure were identified to be of concern for the
general population exposed to environmental releases.
Land Pathway
DCHP has a low water solubility and high affinity for sorption to particulate and organic media. This
indicates that it is unlikely to migrate from land-applied biosolids to groundwater via runoff. DCHP's
potential to leach from landfills into nearby groundwater or surface water systems is also limited.
Therefore, EPA evaluated general population exposures via the land pathway (i.e., application of
biosolids, landfills) qualitatively (Section 4.1.3.1).
Surface Water Pathway
MOEs for general population exposure through incidental ingestion and dermal contact during
swimming ranged from 2,171 to 6,310 for scenarios assuming no wastewater treatment and from 5,521
to 20,000 for scenarios assuming 68.6 percent wastewater treatment removal efficiency (Table 4-16).
Therefore, based on a screening-level assessment, risk for non-cancer health effects is not expectedfor
the surface water pathway, and the pathway is not considered to be a pathway of concern for the
general population.
Acute MOEs through drinking water ingestion were 135 and 430 without and with wastewater
treatment, respectively, for the lifestage (i.e., infants) with the highest exposure (Table 4-16). Based on
the screening-level analysis, risk for non-cancer health effects is not expectedfor the drinking water
pathway, and the drinking water pathway is not considered to be a pathway of concern for the general
population.
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Table 4-16. Summary of the Highest Doses for General Population through Surface and Drinking
Water Exposure
OES"
Water
Column
Concen.
Incidental Dermal
Surface Water6
Incidental Ingestion
Surface Waterc
Drinking Water d
30Q5
Cone.
(Hg/L)
ADRpot
(mg/kg-
day)
Acute MOE
(Benchmark
MOE = 30)
ADRpot
(mg/kg-
day)
Acute MOE
(Benchmark
MOE = 30)
ADRpot
(mg/kg-
day)
Acute MOE
(Benchmark
MOE = 30)
PVC plastics
compounding without
wastewater treatment
126
1.1E-03
2,171
6.7E-04
3,559
1.8E-02
135
PVC plastics
compounding with
wastewater treatment
39.6
3.50E-04
6,913
2.1E-04
11,000
5.6E-03
430
N/A = not applicable
" Table 3-1 provides a crosswalk of industrial and commercial COUs to OES.
h Most exposed age group: Adults (21+ years)
c Most exposed age group: Youth (11-15 years)
d Most exposed age group: Infant (birth to <1 year)
Fish Ingestion
EPA evaluated potential exposure and subsequent risks to DCHP through fish ingestion for populations
and age groups that had the highest fish ingestion rate per kg of body weight—including adults and
young toddlers in the general population, adult subsistence fishers, and adult Tribal populations. Risks
were estimated for various populations and age groups; however, Table 4-17 show only results for the
Tribal populations because it led to the highest exposure.
For the screening-level analysis, EPA started with the water solubility limit as an upper limit of DCHP
concentration in surface water for the general population, subsistence fisher, and Tribal populations.
Screening-level risk estimates were above the benchmark for the general population based on
conservative exposure estimates. Refinements were needed for the subsistence fisher and Tribal
populations because screening-level risk estimates using the water solubility limit were below the
benchmark (see Section 8 of (U.S. EPA. 2024p)V Refinements included use of estimated water releases
by OES, as well as incorporation of various hydrologic flow data for each OES, to model the surface
water concentrations. Briefly, hydrologic flow data were categorized into median flow (P50), 75th
percentile flow (P75), and 90th percentile flow (P90). EPA expects high-end releases to discharge to
surface waters with higher flow conditions (e.g., P75 and P90).
The PVC plastics compounding OES resulted in the highest surface water concentrations. Surface water
concentrations calculated based on the median flow rate led to risk estimates below benchmark for only
Tribal populations ingesting fish at the heritage rate. Heritage rates are not suppressed by contamination,
degradation, or loss of access and existed prior to non-indigenous settlement on Tribal fisheries
resources (U.S. EPA. 2016a). As high-end releases are not expected to discharge to water bodies with
low flow conditions like P50, EPA incorporated higher flow rates and treatment efficiency into its
analysis for Tribal populations. When treatment is considered, risk estimates were above benchmark
even at the P50 condition for all scenarios. Lastly, DCHP is expected to have low potential for
bioaccumulation, biomagnification, and uptake by aquatic organisms because of its low water solubility
and high hydrophobicity as described in Section 4.4. Therefore, fish ingestion is not a pathway of
concern for DCHP for Tribal members, subsistence fishers, or the general population.
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Table 4-17. Fish Ingestion for Adults in Tribal Populations Summary
Calculation Method
Current Mean Ingestion Rate6
(Benchmark MOE = 30)
Heritage Ingestion Rate6
(Benchmark MOE = 30)
ADR/ADD
(mg/kg-day)
Chronic and
Acute MOEfl
ADR/ADD
(mg/kg-day)
Chronic and
Acute MOEfl
Water solubility limit (1.48 mg/L)
2.68E-01
9
2.04
1
Modeled SWC for PVC plastics compounding,
P50 flow (0.087 mg/L)
1.59E-02
151
1.21E-01
20
Modeled SWC for PVC plastics compounding,
P75 flow (3.48E-03 mg/L)
6.30E-04
3,812
4.80E-03
500
Modeled SWC for PVC plastics compounding,
P90 flow (2.4E-04mg/L)
4.40E-05
54,597
3.35E-04
7,163
Modeled SWC for PVC plastics compounding,
P50 flow, Treated (2.7E-02 mg/L)
4.97E-03
482
3.79E-02
63
Highest monitored SWC (1.0E-05 mg/L)
2.53E-06
947,643
1.93E-05
124,326
SWC = surface water concentration
" The acute and chronic MOEs are identical because the exposure estimates and the POD do not change between acute and
chronic.
h Current ingestion rate refers to the present-day consumption levels that are suppressed by contamination degradation or
loss of access. Heritage rates existed prior to non-indigenous settlement on Tribal fishers resources and changes to culture
and life way.
Ambient Air Pathway
As part of the ambient air exposure assessment, EPA considered exposures to the general population in
proximity to releasing facilities, including fenceline communities, by utilizing pre-screening
methodology described in EPA's Draft TSCA Screening Level Approach for Assessing Ambient Air and
Water Exposures to Fenceline Communities (Version 1.0) (U.S. EPA. 2022b). Using the highest
modeled 95th percentile air concentration, MOEs for general population exposure through inhalation are
192 for acute and 281 for chronic (Table 4-18) (compared to a benchmark of 30).
Based on risk screening results, risk for non-cancer health effects is not expectedfor the ambient air
pathway; therefore, the ambient air pathway is not considered to be a pathway of concern to DC HP for
the general population, including fenceline communities.
Table 4-18. General Population Ambient Air Exposure Summary
OESfl
Acute (Daily Average)
Chronic (Annual Average)
Air Concentration6
(jig/m3)
AC
(mg/kg-day)
MOE
Air Concentration6
(jig/m3)
ADC
(mg/kg-day)
MOE
Application of paints
and coatings
67.57
67.57
192
46.28
46.28
281
AC = acute concentration; ADC = average daily concentration; MOE = margin of exposure; OES = occupation
exposure scenario
"Table 1-1 provides a crosswalk of industrial and commercial COUs to OES.
h Air concentrations are reported for the high-end (95th percentile) modeled value at 100 m from the emitting facility
and stack plus fugitive releases combined.
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Urinary Biomonitoring Data - NHANES
CDC stopped collected urinary data for MCHP after 2010. EPA analyzed biomonitoring data from the
1999-2010 NHANES cycle but the low detection rates and limited data variability precluded any
meaningful statistical analyses. Furthermore, EPA's systematic review process did not identify any
suitable alternative sources of DCHP biomonitoring data. Therefore, EPA did not conduct reverse
dosimetry to calculate daily intake values for DCHP (Section 4.1.3.1).
4.3.4.1 Overall Confidence in General Population Screening Level Exposure
Assessment
The weight of scientific evidence supporting the general population exposure estimate is decided based
on the strengths, limitations, and uncertainties associated with the exposure estimates, which are
discussed in detail for ambient air, surface water, drinking water, and fish ingestion in the Draft
Environmental Media, General Population, and Environmental Exposure Assessment for Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024p). EPA summarized its weight of scientific evidence using
confidence descriptors: robust, moderate, slight, or indeterminate. EPA used general considerations {i.e.,
relevance, data quality, representativeness, consistency, variability, uncertainties) as well as chemical-
specific considerations for its weight of scientific evidence conclusions.
EPA determined robust confidence in its qualitative assessment of biosolids and landfills. For its
quantitative assessment, EPA modeled exposure due to various general population exposure scenarios
resulting from different pathways of exposure. Exposure estimates used high-end inputs for the purpose
of risk screening. When available, monitoring data was compared to modeled estimates to evaluate
overlap, magnitude, and trends. EPA has robust confidence that modeled releases used are appropriately
conservative for a screening level analysis. Therefore, EPA has robust confidence that no exposure
scenarios will lead to greater doses than presented in this evaluation. Despite slight and moderate
confidence in the estimated values themselves, confidence in exposure estimates capturing high-end
exposure scenarios was robust given that many of the modeled values exceeded those of monitored
values.
4.3.5 Risk Estimates for Potentially Exposed or Susceptible Subpopulations
EPA considered PESS throughout the exposure assessment and throughout the hazard identification and
dose-response analysis supporting the draft DCHP risk evaluation.
Some population group lifestages may be more susceptible to the health effects of DCHP exposure. As
discussed in Section 4.2 and in EPA's Draft Non-cancer Raman Health Hazard Assessment for
Dicyclohexyl Phthalate (U.S. EPA. 2024v) and Draft Technical Support Document for the Cumulative
Risk Analysis ofDEHP, DBP, BBP, DIBP, DCHP, and DINP Under TSCA (U.S. EPA. 2024ah\
exposure to DCHP causes adverse effects on the developing male reproductive system consistent with a
disruption of androgen action and phthalate syndrome in experimental animal models. Therefore,
women of reproductive age, pregnant women, male infants, male children, and male adolescents are
considered to be susceptible subpopulations. These susceptible lifestages were considered throughout
the draft risk evaluation. For example, women of reproductive age were evaluated for occupational
exposures to DCHP for each COU (Section 4.3.2). Additionally, infants (<1 year), toddlers (1-2 years),
preschoolers (3-5 years), middle school children (6-10 years), young teens (11-15 years), and teenagers
(16-20 years) were evaluated for exposure to DCHP through consumer products and articles (Section
4.3.3). EPA also considered cumulative phthalate exposure and risk for female workers of reproductive
age, as well as male children and female consumers of reproductive age. Additionally, the Agency used
a value of 10 for the UFh to account for human variability. The Risk Assessment Forum, in A Review of
the Reference Dose and Reference Concentration Processes, discusses some of the evidence for
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choosing the default factor of 10 when data are lacking—including toxicokinetic and toxicodynamic
factors as well as greater susceptibility of children and elderly populations (U.S. EPA. 2002b).
The available data suggest that some groups or lifestages have greater exposure to DCHP. This includes
people exposed to DCHP at work, those who frequently use consumer products and/or articles
containing high concentrations of DCHP, those who may have greater intake of DCHP per body weight
(e.g., infants, children, adolescents) leading to greater exposure. EPA accounted for these populations
with greater exposure in the draft DCHP risk evaluation as follows:
• EPA evaluated a range of OESs for workers and ONUs, including high-end exposure scenarios
for women of reproductive age (a susceptible subpopulation) and average adult workers.
• EPA evaluated a range of consumer exposure scenarios, including high-intensity exposure
scenarios for infants and children (susceptible subpopulations). These populations had greater
intake per body weight.
• EPA evaluated a range of general population exposure scenarios, including high-end exposure
scenarios for infants and children (susceptible subpopulations). These populations had greater
intake per body weight.
• EPA evaluated exposure to DCHP through fish ingestion for subsistence fishers and Tribal
populations.
• EPA aggregated occupational inhalation and dermal exposures for each COU for women of
reproductive age (a susceptible subpopulation) and average adult workers.
• EPA aggregated consumer inhalation, dermal, and oral exposures for each COU for infants and
children (susceptible subpopulations).
• EPA evaluated cumulative exposure to DEHP, DBP, BBP, DIBP, and DINP for the U.S. civilian
population using NHANES urinary biomonitoring data and reverse dosimetry for women of
reproductive age (16-49 years) and male children (3-5, 6-11, and 12-15 years of age).
• For women of reproductive age, black non-Hispanic women had higher, albeit not statistically
significantly higher, 95th percentile cumulative exposures to DEHP, DBP, BBP, DIBP, and
DINP compared to women of other races (e.g., white non-Hispanic, Mexican America). The 95th
percentile cumulative exposure estimate for black non-Hispanic women served as the non-
attributable national cumulative exposure estimate used by EPA to evaluate cumulative risk to
workers and consumers.
4.4 Human Health Cumulative Risk Assessment and Characterization
EPA developed a Draft Technical Support Document for the Cumulative Risk Analysis of DEHP, DBP,
BBP, DIBP, DCHP, and DINP Under TSCA (U.S. EPA. 2024ah) (draft CRA TSD) for the CRA of six
toxicologically similar phthalates being evaluated under Section 6 of the Toxic Substances Control Act
(TSCA): di(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP),
dicyclohexyl phthalate (DCHP), diisobutyl phthalate (DIBP), and diisononyl phthalate (DINP). EPA
previously issued a Draft Proposed Approach for Cumulative Risk Assessment of High-Priority
Phthalates and a Manufacturer-Requested Phthalate under the Toxic Substances Control Act (draft
2023 approach), which outlined an approach for this assessment (U.S. EPA. 2023c). EPA's proposal
was subsequently peer-reviewed by the Science Advisory Committee on Chemicals (SACC) in May
2023 (U.S. EPA. 2023f). In the 2023 draft approach, EPA identified a cumulative chemical group and
PESS [15 U.S.C. section 2605(b)(4)], Based on toxicological similarity and induced effects on the
developing male reproductive system consistent with a disruption of androgen action and phthalate
syndrome, EPA proposed a cumulative chemical group of DEHP, BBP, DBP, DCHP, DIBP, and DINP,
but not diisodecyl phthalate (DIDP). This approach emphasizes a uniform measure of hazard for
sensitive subpopulations, namely women of reproductive age and/or male infants and children, however
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additional health endpoints are known for broader populations and described in the individual non-
cancer human health hazard assessments for DEHP (U.S. EPA. 2024w). DBP (U.S. EPA. 2024u). DIBP
(U.S. EPA. 2024x). BBP (U.S. EPA. 2024f). DCHP (U.S. EPA. 2024v). and DINP (U.S. EPA. 2025b).
including hepatic, kidney, and other developmental and reproductive toxicity.
EPA's approach for assessing cumulative risk is described in detail in the draft CRA TSD (U.S. EPA.
2024ah) and incorporates feedback from the SACC (U.S. EPA. 2023f) on EPA's 2023 draft proposal
(U.S. EPA. 2023 c). EPA is focusing its CRA on acute duration exposures of women of reproductive
age, male infants, and male children to six toxicologically similar phthalates {i.e., DEHP, DBP, BBP,
DIBP, DCHP, DINP) that induce effects on the developing male reproductive system consistent with a
disruption of androgen action and phthalate syndrome. The Agency is further focusing its CRA on acute
duration exposures because there is evidence that effects on the developing male reproductive system
consistent with a disruption of androgen action can result from a single exposure during the critical
window of development (see Section 1.5 of (U.S. EPA. 2024ah) for further details). To evaluate
cumulative risk, EPA is using a relative potency factor (RPF) approach. RPFs for DEHP, DBP, BBP,
DIBP, DCHP, and DINP were developed using a meta-analysis and benchmark dose (BMD) modeling
approach based on a uniform measure (i.e., reduced fetal testicular testosterone). EPA is also using
NHANES data to supplement, not substitute, evaluations for exposure scenarios for TSCA COUs to
provide non-attributable, total exposure for addition to the relevant scenarios presented in the individual
risk evaluations.
The analogy of a "risk cup" is used throughout this document to describe cumulative exposure estimates.
The risk cup term is used to help conceptualize the contribution of various phthalate exposure routes and
pathways to overall cumulative risk estimates and serves primarily as a communication tool. The term/
concept describes exposure estimates where the full cup represents the total exposure that leads to risk
(cumulative MOE) and each chemical contributes a specific amount of exposure that adds a finite
amount of risk to the cup. A full risk cup indicates that the cumulative MOE has dropped below the
benchmark MOE (i.e., total UF), whereas cumulative MOEs above the benchmark indicate that only a
percentage of the risk cup is full.
The remainder of the human health CRA is organized as follows:
• Section 4.4.1 - Describes the approach used by EPA to derive draft relative potency factors for
DEHP, DBP, BBP, DIBP, DCHP, and DINP based on reduced fetal testicular testosterone,
which are used by EPA as part of the current CRA and to assess exposures to individual
phthalates by scaling to an index chemical (RPF analysis). Section 2 of EPA's draft CRA TSD
(U.S. EPA. 2024ah) provides more details.
• Section 4.4.2 - Briefly describes the approach used by EPA to calculate cumulative non-
attributable phthalate exposure for the U.S. population using NHANES urinary biomonitoring
and reverse dosimetry. Section 4 of EPA's draft CRA TSD (U.S. EPA. 2024ah) provides
additional details.
• Section 4.4.3 - Describes how EPA combined exposures to DCHP from individual consumer
and occupational COUs/OES with cumulative non-attributable phthalate exposures from
NHANES to estimate cumulative risk. An empirical example is also provided. Section 5 of
EPA's draft CRA TSD (U.S. EPA. 2024ah) provides additional details.
For additional details regarding EPA's draft CRA, readers are directed to the following TSDs:
• Draft Technical Support Document for the Cumulative Risk Analysis of Di(l-ethylhexyl)
Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl
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Phthalate (DIBP), Dicyclohexyl Phthalate (DCHP), and Diisononyl Phthalate (DINP) Under the
Toxic Substances Control Act (TSCA) (U.S. EPA. 2024ah);
• Draft Meta-Analysis and Benchmark Dose Modeling of Fetal Testicular Testosterone for Di(2-
ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBF), Butyl Benzyl Phthalate (BBP),
Diisobutyl Phthalate (DIBP), and Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024s);
• Draft Proposed Approach for Cumulative Risk Assessment of High-Priority Phthalates and a
Manufacturer-Requested Phthalate under the Toxic Substances Control Act (U.S. EPA. 2023 c);
• Draft Proposed Principles of Cumulative Risk Assessment under the Toxic Substances Control
Act (U.S. EPA. 2023d); and
• Science Advisory Committee on Chemicals meeting minutes andfinal report, No. 2023-01 - A set
of scientific issues being considered by the Environmental Protection Agency regarding: Draft
Proposed Principles of Cumulative Risk Assessment (CRA) under the Toxic Substances Control
Act and a Draft Proposed Approach for CRA of High-Priority Phthalates and a Manufacturer-
Requested Phthalate (U.S. EPA. 2023f).
4.4.1 Hazard Relative Potency
This section briefly summarizes the RPF approach used by EPA to evaluate phthalates for cumulative
risk. Section 4.4.1.1 provides a brief overview and background for the RPF approach methodology,
while Section 4.4.1.2 provides a brief overview of the draft RPFs derived by EPA for DEHP, DBP,
BBP, DIBP, DCHP, and DINP based on decreased fetal testicular testosterone. Further details regarding
the draft relative potency analysis conducted by EPA are provided in the following two TSDs:
• Draft Technical Support Document for the Cumulative Risk Analysis of Di(2-ethylhexyl)
Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl
Phthalate (DIBP), Dicyclohexyl Phthalate (DCHP), and Diisononyl Phthalate (DINP) Under the
Toxic Substances Control Act (TSCA) (U.S. EPA. 2024ah); and
• Draft Meta-Analysis and Benchmark Dose Modeling of Fetal Testicular Testosterone for Di(2-
ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP),
Diisobutyl Phthalate (DIBP), and Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024s).
4.4.1.1 Relative Potency Factor Approach Overview
For the RPF approach, chemicals being evaluated require data that support toxicologic similarity (e.g.,
components of a mixture share a known or suspected common MOA or share a common apical
endpoint/effect) and have dose-response data for the effect of concern over similar exposure ranges
(U.S. EPA. 2023a. 2000. 1986). RPF values account for potency differences among chemicals in a
mixture and scale the dose of one chemical to an equitoxic dose of another chemical (i.e., the index
chemical). The chemical selected as the index chemical is often among the best characterized
toxicologically and considered to be representative of the type of toxicity elicited by other components
of the mixture. Implementing an RPF approach requires a quantitative dose-response assessment for the
index chemical and pertinent data that allow the potency of the mixture components to be meaningfully
compared to that of the index chemical. In the RPF approach, RPFs are calculated as the ratio of the
potency of the individual component to that of the index chemical using either (1) the response at a fixed
dose, or (2) the dose at a fixed response (Equation 4-3).
Equation 4-3. Calculating RPFs
bmdr_ic
Rpp. =
BMD
R-i
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Where:
BMD = Benchmark dose (mg/kg/day)
R = Magnitude of response {i.e., benchmark response)
/ = ith chemical
IC = Index chemical
After scaling the chemical component doses to the potency of the index chemical, the scaled doses are
summed and expressed as index chemical equivalents for the mixture (Equation 4-4).
Equation 4-4. Calculating Index Chemical Equivalents
n
Index Chemical EquivalentsMIX = ^ d-i x RPFi
Where:
i=i
Index chemical equivalents = Dose of the mixture in index chemical equivalents
(mg/kg/day)
di = Dose of the ith chemical in the mixture (mg/kg/day)
RPFi = Relative potency factor of the ith chemical in the mixture
(unitless)
Non-cancer risk associated with exposure to an individual chemical or the mixture can then be assessed
by calculating an MOE, which in this case is the ratio of the index chemical's non-cancer hazard value
(e.g., the BMDL) to an estimate of exposure expressed in terms of index chemical equivalents. The
MOE is then compared to the benchmark MOE (i.e., the total uncertainty factor associated with the
assessment) to characterize risk.
4.4.1.2 Relative Potency Factors
Derivation of Draft RPFs
To derive RPFs for DEHP, DBP, BBP, DIBP, DCHP, and DINP, EPA utilized a meta-analysis and
BMD modeling approach similar to that used by NASEM (2017) to model decreased fetal testicular
testosterone. As described further in EPA's Draft Meta-Analysis and Benchmark Dose Modeling of
Fetal Testicular Testosterone for DEHP, DBP, BBP, DIBP, and DCHP (U.S. EPA. 2024s). the Agency
evaluated benchmark responses (BMRs) of 5, 10, and 40 percent. For input into the CRA of phthalates,
EPA has derived draft RPFs using BMD40 estimates (Table 4-19). For further details regarding RPFs
derivation, see Section 2 of EPA's Draft Technical Support Document for the Cumulative Risk Analysis
of DEHP, DBP, BBP, DIBP, DCHP, and DINP Under TSCA (U.S. EPA. 2024ahY
Selection of the Index Chemical
Of the six phthalates being evaluated for cumulative risk under TSCA (i.e., DEHP, DBP, BBP, DIBP,
DCHP, and DINP), EPA has preliminarily selected DBP as the index chemical.
As described further in Section 2 of EPA's Draft Technical Support Document for the Cumulative Risk
Analysis of DEHP, DBP, BBP, DIBP, DCHP, and DINP under TSCA (U.S. EPA. 2024ah). EPA selected
DBP as the index chemical DBP has a high-quality toxicological database of studies demonstrating
effects on the developing male reproductive system consistent with a disruption of androgen action and
phthalate syndrome. Furthermore, studies of DBP demonstrate toxicity representative of all phthalates in
the cumulative chemical group and DBP is well characterized for the MOA associated with phthalate
syndrome. Finally, compared to other phthalates, including well-studied phthalates such as DEHP, DBP
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has the most dose-response data available in the low-end range of the dose-response curve where the
BMDs and BMDL5 are derived, which provides a robust and scientifically sound foundation of BMD
and BMDL estimates on which the RPF approach is based.
Table 4-19. Draft Relative Potency Factors Based on
Decreased Fetal Testicular Testosterone
Phthalate
BMD40
(mg/kg-day)
RPF Based on
BMD40
DBP (Index chemical)
149
1
DEHP
178
0.84
DffiP
279
0.53
BBP
284
0.52
DCHP
90
1.66
DINP
699
0.21
Index Chemical POD
As with any risk assessment that relies on BMD analysis, the POD is the lower confidence limit used to
mark the beginning of extrapolation to determine risk associated with human exposures. As described
further in the non-cancer human health hazards of DEHP (U.S. EPA. 2024w). DBP (U.S. EPA. 2024u).
BBP (U.S. EPA. 2024t). DffiP (U.S. EPA. 2024x1 DCHP (U.S. EPA. 2024v). and DINP (U.S. EPA.
2025b) (see Appendices titled "Considerations for Benchmark Response (BMR) Selection for Reduced
Fetal Testicular Testosterone" in each hazard assessment), EPA has reached the conclusion that a BMR
of 5 percent is the most appropriate and health protective response level for evaluating decreased fetal
testicular testosterone. For the index chemical, DBP, the BMDL5 for the best fitting linear-quadratic
model is 9 mg/kg-day for reduced fetal testicular. Using allometric body weight scaling to the three-
quarters power (U.S. EPA. 201 lc). EPA extrapolated an HED of 2.1 mg/kg-day to use as the POD for
the index chemical in the CRA.
Selection of the Benchmark MOE
Consistent with Agency guidance (U.S. EPA. 2022c. 2002b). EPA selected an intraspecies uncertainty
factor (UFh) of 10, which accounts for variation in susceptibility across the human population and the
possibility that the available data might not be representative of individuals who are most susceptible to
the effect. EPA used allometric body weight scaling to the three-quarters power to derive an HED of 2.1
mg/kg-day DBP, which accounts for species differences in toxicokinetics. Consistent with EPA
Guidance (U.S. EPA. 2011c). the interspecies uncertainty factor (UFa), was reduced from 10 to 3 to
account remaining uncertainty associated with interspecies differences in toxicodynamics. Overall, a
total uncertainty factor of 30 was selectedfor use as the benchmark margin of exposure for the CRA
(based on a interspecies uncertainty factor [UFa] of 3 and a intraspecies uncertainty factor [UFh] of 10).
Weight of Scientific Evidence
EPA has preliminary selected an HED of 2.1 mg/kg-day (BMDL5 of 9 mg/kg-day) as the index chemical
(DBP) POD. This POD is based on a meta-analysis and BMD modeling of decreased fetal testicular
testosterone from eight studies of rats gestationally exposed to DBP. The Agency EPA has also derived
draft RPFs of 1, 0.84, 0.53, 0.52, 1.66, and 0.21 for DBP (index chemical), DEHP, DffiP, BBP, DCHP,
and DINP, respectively, based on a common toxicological outcome (i.e., reduced fetal testicular
testosterone). EPA has robust overall confidence in the proposed POD for the index chemical (i.e.,
DBP) and the derived draft RPFs.
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Application of RPF provides a more robust basis for assessing the dose-response to the common hazard
endpoint across all assessed phthalates. For DCHP and a subset of the phthalates with a more limited
toxicological data set, scaling by the RPF and application of the index chemical POD provides a more
sensitive and robust hazard assessment than the chemical-specific POD. Readers are directed to the
Draft Technical Support Document for the Cumulative Risk Analysis ofDEHP, DBF, BBP, DIBP,
DCHP, and DINP Under TSCA (U.S. EPA. 2024ah) for a discussion of the weight of evidence
supporting EPA's preliminary conclusions.
4.4.2 Cumulative Phthalate Exposure: Non-attributable Cumulative Exposure to DEHP,
DBP, BBP, DIBP, and DINP Using NHANES Urinary Biomonitoring and Reverse
Dosimetry
This section briefly summarizes EPA's approach and results for estimating non-attributable cumulative
exposure to phthalates using NHANES urinary biomonitoring data and reverse dosimetry. Readers are
directed to Section 4 of EPA's Draft Technical Support Document for the Cumulative Risk Analysis of
DEHP, DBP, BBP, DIBP, DCHP, and DINP Under TSCA (U.S. EPA. 2024ah) for additional details.
NHANES is an ongoing exposure assessment of the U.S. population's exposure to environmental
chemicals using biomonitoring. The NHANES biomonitoring data set is a national, statistical
representation of the general, non-institutionalized, civilian U.S. population. CDC's NHANES data set
provides an estimate of average aggregate exposure to individual phthalates for the U.S. population.
However, exposures measured via NHANES cannot be attributed to specific sources, such as TSCA
COUs or other sources. Given the short half-lives of phthalates, neither can NHANES capture acute, low
frequency exposures. Instead, as concluded by the SACC review of the draft 2023 approach, NHANES
provides a "snapshot" or estimate of total, non-attributable phthalate exposure for the U.S. population
and relevant subpopulations (U.S. EPA. 2023f). These estimates of total non-attributable exposure can
supplement assessments of scenario-specific acute risk in individual risk evaluations.
Monoester metabolites of BBP, DBP, DEHP, DIBP, and DINP in human urine are regularly measured
as part of the NHANES biomonitoring program and are generally detectable in human urine at a high
frequency, including during the most recent NHANES survey period (i.e., 2017-2018). One urinary
metabolite (i.e., monocyclohexyl phthalate [MCHP]) of DCHP was included in NHANES from 1999
through 2010, but was excluded from NHANES after 2010 due to low detection levels and a low
frequency of detection in human urine (detected in <10% of samples in 2009-2010 NHANES survey)
(CDC. 2013).Therefore. EPA did not use NHANES urinary biomonitoring data to estimate a daily
aggregate intake value for DCHP through reverse dosimetry.
EPA used urinary phthalate metabolite concentrations for DEHP, DBP, BBP, DIBP, and DINP
measured in the most recently available NHANES survey (2017-2018) to estimate the average daily
aggregate intake of each phthalate through reverse dosimetry for
• Women of reproductive age (16-49 years);
• Male children (4 to <6 years, used as a proxy for male infants and toddlers);
• Male children (6-11 years); and
• Male children (12 to <16 years).
Since NHANES does not include urinary biomonitoring for infants or toddlers, and other national data
sets are not available, EPA used biomonitoring data from male children 3 to less than 6 years of age as a
proxy for male infants (<1 year) and male toddlers (1-2 years). See Section 4 of (U.S. EPA. 2024ah) for
further details regarding the reverse dosimetry approach. Aggregate daily intake estimates for these
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populations are presented in Table 4-20.4 Aggregate daily intake values were also calculated for women
of reproductive age stratified by race and socioeconomic status (Table 4-21). A similar analysis by race
was not done for male children because the NHANES sample size is smaller for this population.
Aggregate daily intake values for each phthalate were then scaled by relative potency using the RPFs in
Table 4-19, expressed in terms of index chemical (DBP) equivalents, and summed to estimate
cumulative daily intake in terms of index chemical (DBP) equivalents using the approach outlined in
Sections 4.4.1 and 4.4.3.
Since EPA is focusing its CRA on acute exposure durations, EPA selected 95th percentile exposure
estimates from NHANES to serve as the non-attributable nationally representative exposure estimate for
use in its CRA. For women of reproductive age, EPA's analysis indicates that black, non-Hispanic
women have slightly higher 95th percentile cumulative phthalate exposure compared to other racial
groups; thus, 95th percentile cumulative exposure estimates for black non-Hispanic women of
reproductive age was selected for use in the CRA of DCHP (Table 4-20).
The 95th percentile of national cumulative exposure serves as the estimate of non-attributable phthalate
exposure for its CRA of DCHP as follows:
• Women of reproductive age (16-49 years, black Non-Hispanic): 5.16 |ig/kg-day index chemical
(DBP) equivalents. This serves as the non-attributable contribution to worker and consumer
women of reproductive age in Section 4.4.4 and Section 4.4.5.
• Males (3-5 years): 10.8 |ig/kg-day index chemical (DBP) equivalents. This serves as the non-
attributable contribution to consumer male infants (<1 year), toddlers (1-2 years), and
preschoolers (3-5 years) in Section 4.4.5. Since NHANES does not include urinary
biomonitoring for infants (<1 year) or toddlers (1-2 years), and other national data sets are not
available, EPA used biomonitoring data from male children (3 to <6 years) as a proxy for male
infants and toddlers.
• Males (6-11 years): 7.35 |ig/kg-day index chemical (DBP) equivalents This serves as the non-
attributable contribution to consumer male children (6-10 years) in Section 4.4.5.
• Males (12-15 years): 4.36 |ig/kg-day index chemical (DBP) equivalents. This serves as the non-
attributable contribution to consumer male teenagers (11-15 years) in Section 4.4.5.
4.4.2.1.1 Weight of Scientific Evidence: Non-attributable Cumulative Exposure to
Phthalates
Overall, EPA has robust confidence in the derived estimates of non-attributable cumulative exposure
fi'om NHANES urinary biomonitoring using reverse dosimetry. The Agency EPA used urinary
biomonitoring data from the CDC's national NHANES dataset, which provides a statistical
representation of the general, non-institutionalized, civilian U.S. population. To estimate daily intake
values from urinary biomonitoring for each phthalate, EPA used reverse dosimetry. The reverse
dosimetry approach used by EPA has been used extensively in the literature and has been used by CPSC
(2014) and Health Canada (ECCC/HC. 2020) to estimate phthalate daily intake values from urinary
biomonitoring data. However, given the short half-lives of phthalates, NHANES biomonitoring data is
not expected to capture low frequency exposures and may be an underestimate of acute phthalate
exposure.
4 EPA defines aggregate exposure as the "combined exposures to an individual from a single chemical substance across
multiple routes and across multiple pathways" (40 CFR section 702.33).
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3103 Table 4-20. Cumulative Phthalate Daily Intake (jig/kg-day) Estimates for Women of Reproductive Age, Male Children, and Male
3104 Teenagers from the 2017-2018 NHANES Cycle
Population
Percentile
Phthalate
Aggregate
Daily Intake
(jig/kg-day)
RPF
Aggregate
Daily Intake
in DBP
Equivalents
(jig/kg-day)
%
Contribution
to Cumulative
Exposure
Cumulative Daily
Intake
(DBP Equivalents,
jig/kg-day)
Cumulative
MOE (POD =
2,100 jig/kg-
day)
% Contribution
to Risk Cup
(Benchmark =
30)fl
DBP
0.21
1
0.210
22.1
DEHP
0.53
0.84
0.445
46.9
50
BBP
0.08
0.52
0.042
4.38
0.950
2,211
1.4%
Females
(16-49 years;
n = 1,620)
DIBP
0.2
0.53
0.106
11.2
DINP
0.7
0.21
0.147
15.5
DBP
0.61
1
0.610
17.2
DEHP
1.48
0.84
1.24
35.0
95
BBP
0.42
0.52
0.218
6.15
3.55
592
5.1%
DIBP
0.57
0.53
0.302
8.51
DINP
5.6
0.21
1.18
33.1
DBP
0.56
1
0.560
18.4
DEHP
2.11
0.84
1.77
58.2
50
BBP
0.22
0.52
0.114
3.76
3.04
690
4.3%
Males
(3-5 years;
n = 267)
DIBP
0.57
0.53
0.302
9.93
DINP
1.4
0.21
0.294
9.66
DBP
2.02
1
2.02
18.6
DEHP
6.44
0.84
5.41
49.9
95
BBP
2.46
0.52
1.28
11.8
10.8
194
15.5%
DIBP
2.12
0.53
1.12
10.4
DINP
4.8
0.21
1.01
9.30
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Population
Percentile
Phthalate
Aggregate
Daily Intake
(jig/kg-day)
RPF
Aggregate
Daily Intake
in DBP
Equivalents
(jig/kg-day)
%
Contribution
to Cumulative
Exposure
Cumulative Daily
Intake
(DBP Equivalents,
jig/kg-day)
Cumulative
MOE (POD =
2,100 jig/kg-
day)
% Contribution
to Risk Cup
(Benchmark
30)
DBP
0.38
1
0.380
20.1
DEHP
1.24
0.84
1.04
55.1
50
BBP
0.16
0.52
0.083
4.40
1.89
1,111
2.7%
Males
(6-11 years;
n = 553)
DIBP
0.33
0.53
0.175
9.26
DINP
1
0.21
0.210
11.1
DBP
1.41
1
1.41
19.2
DEHP
4.68
0.84
3.93
53.5
95
BBP
0.84
0.52
0.437
5.94
7.35
286
10.5%
DIBP
1.62
0.53
0.859
11.7
DINP
3.4
0.21
0.714
9.71
DBP
0.33
1
0.330
27.6
DEHP
0.66
0.84
0.554
46.4
50
BBP
0.14
0.52
0.073
6.09
1.19
1,758
1.7%
Males
(12-15 years;
n = 308)
DIBP
0.21
0.53
0.111
9.32
DINP
0.6
0.21
0.126
10.5
DBP
0.62
1
0.620
14.2
DEHP
2.51
0.84
2.11
48.3
95
BBP
0.64
0.52
0.333
7.63
4.36
482
6.2%
DIBP
0.59
0.53
0.313
7.17
DINP
4.7
0.21
0.987
22.6
11A cumulative exposure of 70 |_ig DBP equivalents/kg-day would result in a cumulative MOE of 30 (i.e., 2,100 |_ig DBP-equivalents/kg-day ^ 70 |_ig DBP
equivalents/kg-day = 30), which is equivalent to the benchmark of 30, indicating that the exposure is at the threshold for risk. Therefore, to estimate the percent
contribution to the risk cup, the cumulative exposure expressed in DBP equivalents is divided by 70 |_ig DBP equivalents/kg-day to estimate percent contribution
to the risk cup.
3105
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3107 Table 4-21. Cumulative Phthalate Daily Intake (jig/kg-day) Estimates for Women of Reproductive Age (16-49 years old) by Race and
3108 Socioeconomic Status from the 2017-2018 NHANES Cycle
Race/
Socioeconomic
Status (SES)
Percentile
Phthalate
Aggregate
Daily Intake
(jig/kg-day)
RPF
Aggregate
Daily Intake
in DBP
Equivalents
(jig/kg-day)
%
Contribution to
Cumulative
Exposure
Cumulative Daily
Intake
(DBP Equivalents,
jig/kg-day)
Cumulative
MOE (POD
= 2,100
jig/kg-day)
% Contribution
to Risk Cup
(Benchmark =
30)fl
DBP
0.22
1
0.22
21.6
DEHP
0.59
0.84
0.50
48.6
50
BBP
0.10
0.52
0.05
5.1
1.02
2,058
1.5%
Race: white non-
Hispanic
(n = 494)
DIBP
0.20
0.53
0.11
10.4
DINP
0.70
0.21
0.15
14.4
DBP
0.58
1
0.58
17.6
DEHP
1.44
0.84
1.21
36.6
95
BBP
0.29
0.52
0.15
4.6
3.30
636
4.7%
DIBP
0.55
0.53
0.29
OO
00
DINP
5.10
0.21
1.07
32.4
DBP
0.10
1
0.10
15.0
DEHP
0.38
0.84
0.32
47.9
50
BBP
0.04
0.52
0.02
3.1
0.667
3,151
1.0%
Race: black non-
Hispanic
(n = 371)
DIBP
0.15
0.53
0.08
11.9
DINP
0.70
0.21
0.15
22.1
DBP
0.48
1
0.48
9.3
DEHP
4.28
0.84
3.60
69.7
95
BBP
0.30
0.52
0.16
3.0
5.16
407
7.4%
DIBP
0.40
0.53
0.21
4.1
DINP
3.40
0.21
0.71
13.8
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Race/
Socioeconomic
Status (SES)
Percentile
Phthalate
Aggregate
Daily Intake
(jig/kg-day)
RPF
Aggregate
Daily Intake
in DBP
Equivalents
(jig/kg-day)
%
Contribution to
Cumulative
Exposure
Cumulative Daily
Intake
(DBP Equivalents,
jig/kg-day)
Cumulative
MOE (POD
= 2,100
jig/kg-day)
% Contribution
to Risk Cup
(Benchmark =
30)fl
DBP
0.19
1
0.19
22.4
DEHP
0.49
0.84
0.41
48.5
50
BBP
0.06
0.52
0.03
3.7
0.849
2,474
1.2%
Race: Mexican
American
(n = 259)
DIBP
0.17
0.53
0.09
10.6
DINP
0.60
0.21
0.13
14.8
DBP
0.42
1
0.42
11.6
DEHP
1.24
0.84
1.04
28.9
95
BBP
0.39
0.52
0.20
5.6
3.61
582
5.2%
DIBP
0.46
0.53
0.24
6.8
DINP
8.10
0.21
1.70
47.1
DBP
0.26
1
0.26
25.3
DEHP
0.64
0.84
0.54
52.2
50
BBP
0.07
0.52
0.04
3.5
1.03
2041
1.5%
DIBP
0.15
0.46
0.07
6.7
Race: Other
DINP
0.60
0.21
0.13
12.2
(n = 496)
DBP
0.84
1
0.84
20.7
DEHP
1.37
0.84
1.15
28.3
95
BBP
0.41
0.52
0.21
5.2
4.06
517
5.8%
DIBP
0.46
0.53
0.24
6.0
DINP
7.70
0.21
1.62
39.8
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Race/
Socioeconomic
Status (SES)
Percentile
Phthalate
Aggregate
Daily Intake
(jig/kg-day)
RPF
Aggregate
Daily Intake
in DBP
Equivalents
(jig/kg-day)
%
Contribution to
Cumulative
Exposure
Cumulative Daily
Intake
(DBP Equivalents,
jig/kg-day)
Cumulative
MOE (POD
= 2,100
jig/kg-day)
% Contribution
to Risk Cup
(Benchmark =
30)fl
SES: Below
poverty level
(n = 1,056)
50
DBP
0.21
1
0.21
22.0
0.955
2,199
1.4%
DEHP
0.53
0.84
0.45
46.6
BBP
0.09
0.52
0.05
4.9
DIBP
0.20
0.53
0.11
11.1
DINP
0.70
0.21
0.15
15.4
95
DBP
0.82
1
0.82
18.2
4.50
467
6.4%
DEHP
1.75
0.84
1.47
32.7
BBP
0.34
0.52
0.18
3.9
DIBP
0.51
0.53
0.27
6.0
DINP
8.40
0.21
1.76
39.2
SES: At or
above poverty
level
(n = 354)
50
DBP
0.20
1.00
0.20
27.9
0.718
2,924
1.0%
DEHP
0.31
0.84
0.26
36.3
BBP
0.06
0.52
0.03
4.3
DIBP
0.15
0.53
0.08
11.1
DINP
0.70
0.21
0.15
20.5
95
DBP
0.48
1.00
0.48
16.3
2.94
713
4.2%
DEHP
1.07
0.84
0.90
30.5
BBP
0.45
0.52
0.23
7.9
DIBP
0.65
0.53
0.34
11.7
DINP
4.70
0.21
0.99
33.5
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Race/
Socioeconomic
Status (SES)
Percentile
Phthalate
Aggregate
Daily Intake
(jig/kg-day)
RPF
Aggregate
Daily Intake
in DBP
Equivalents
(jig/kg-day)
%
Contribution to
Cumulative
Exposure
Cumulative Daily
Intake
(DBP Equivalents,
jig/kg-day)
Cumulative
MOE (POD
= 2,100
jig/kg-day)
% Contribution
to Risk Cup
(Benchmark =
30)fl
DBP
0.26
1.00
0.26
23.2
DEHP
0.67
0.84
0.56
50.1
50
BBP
0.06
0.52
0.03
2.8
1.12
1,870
1.6%
DIBP
0.23
0.53
0.12
10.9
SES: Unknown
DINP
0.70
0.21
0.15
13.1
(n = 210)
DBP
0.60
1.00
0.60
25.5
2.35
893
3.4%
DEHP
0.86
0.84
0.72
30.7
95
BBP
0.21
0.52
0.11
4.6
DIBP
0.35
0.53
0.19
7.9
DINP
3.50
0.21
0.74
31.2
11A cumulative exposure of 70 |_ig DBP equivalents/kg-day would result in a cumulative MOE of 30 (i.e., 2,100 |_ig DBP-equivalents/kg-day ^ 70 |_ig DBP
equivalents/kg-day = 30), which is equivalent to the benchmark of 30, indicating that the exposure is at the threshold for risk. Therefore, to estimate the percent
contribution to the risk cup, the cumulative exposure expressed in DBP equivalents is divided by 70 |_ig DBP equivalents/kg-day to estimate percent contribution
to the risk cup.
3109
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4.4.3 Estimation of Risk Based on Relative Potency
As described in the Draft Technical Support Document for the Cumulative Risk Analysis ofDEHP,
DBP, BBP, DIBP, DCHP, andDINP under TSCA (U.S. EPA. 2024ah). EPA is focusing its exposure
assessment for the CRA for DCHP on evaluation of exposures through individual TSCA consumer and
occupational DCHP COUs as well as non-attributable cumulative exposure to DEHP, DBP, BBP, DIBP,
and DINP using NHANES urinary biomonitoring data and reverse dosimetry. To estimate cumulative
risk, EPA first scaled all phthalate exposures by relative potency using the RPFs presented in Table 4-19
to express phthalate exposure in terms of index chemical (DBP) equivalents. Exposures from individual
DCHP consumer or worker COUs/OES were then combined to estimate cumulative risk. Cumulative
risk was estimated using the four-step process outlined below, along with one empirical example of how
EPA calculated cumulative risk for one occupational OES for DCHP (i.e., Application of paints and
coatings [solids]).
Step 1: Convert DCHP Exposure Estimates from Each Individual Consumer and Occupational COU
to Index Chemical Equivalents (i. e., Occupational and Consumer Exposure from Sections 4.1.1 and
4.1.2, Respectively)
In this step, DCHP acute duration exposure estimates from each consumer and occupational COU/OES
are scaled by relative potency and expressed in terms of index chemical (DBP) equivalents using
Equation 4-5. This step is repeated for all individual exposure estimates for each route of exposure being
assessed for each COU (i.e., inhalation and dermal exposures for occupational COUs; inhalation,
ingestion, and dermal exposure for consumer COUs).
Equation 4-5. Scaling DCHP Exposures by Relative Potency
DCHP Exposure (in DBP equivalents) = ADRoute xx RPFdchp
Where:
DCHP exposure = Acute exposure for a given route of exposure from a single
occupational or consumer COU expressed in terms of |ig/kg index
chemical (DBP) equivalents
ADRoute l = Acute dose in |ig/kg from a given route of exposure from a single
occupational or consumer COU/OES
RPFdchp = The relative potency factor (unitless) for DCHP, which is 1.66
(Table 4-19).
Example: 50th percentile inhalation and dermal DCHP exposures for female workers of reproductive
age are 38.7 and 2.07 |ig/kg for the Application of paints and coatings (solids) OES (U.S. EPA. 2024ab).
Using Equation 4-5, inhalation, dermal, and aggregate DCHP exposures for this OES can be scaled by
relative potency to 64.2, 3.44, and 67.68 |ig/kg DBP equivalents, respectively.
DCHPInhalation_cou = 64.2 M-g/kg DBP equivalents = 38.7 [ig/kgDCHP x 1.66
DCHPDermal_cou = 3.44 [ig/kgDBP equivalents = 2.07 |ig/kg DCHP x 1.66
DCHPAggregate_cou = 67.68 |ig/kg DBP equivalents
= (2.07 [ig/kgDCHP + 38.7 |ig/kgDCHP) x 1.66
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Step 2: Estimate Non-attributable Cumulative Exposure to DEHP, DBP, BBP, DIBP, and DINP
Using NHANES Urinary Biomonitoring Data and Reverse Dosimetry (see Section 4.4.2 for Further
Details)
Non-attributable exposure for a national population to DEHP, DBP, BBP, DIBP, and DINP was
estimated using Equation 4-6, where individual phthalate daily intake values estimated from NHANES
biomonitoring data and reverse dosimetry were scaled by relative potency, expressed in terms of index
chemical (DBP) equivalents, and summed to estimate non-attributable cumulative exposure in terms of
DBP equivalents. Equation 4-6 was used to calculate the cumulative exposure estimates provided in
Table 4-20 and Table 4-21.
Equation 4-6. Estimating Non-attributable Cumulative Exposure to DEHP, DBP, BBP, DIBP, and
DINP
Cumulative Exposure (Non — attributable)
= (DIdehp x RPFdehp) + (DIdbp x RPFdbp) + (DIbbp x RPFbbp)
+ (DIdibp x RPFdibp) + (DIdinp x RPFdinp)
Where:
Cumulative exposure (non-attributable) is expressed in index chemical (DBP) equivalents
(lig/kg-day).
DI is The daily intake value (|ig/kg-day) for each phthalate that was calculated using NHANES
urinary biomonitoring data and reverse dosimetry (DI) values for each phthalate for each
assessed population are provided in Table 4-20 and Table 4-21).
RPF is the relative potency factor (unitless) for each phthalate from Table 4-19.
Example: The 95th percentile cumulative exposure estimate of 5.16 |ig/kg-day DBP equivalents for
black, non-Hispanic women of reproductive age (Table 4-21) is calculated using Equation 4-6 as
follows:
5.16 [ig/kgDBP equivalents
= (4.28 |ig/kg DEHP x 0.84) + (0.48 |ig/kg DBP x 1) + (0.30 |ig/kg BBP x 0.52)
+ (0.40 [ig/kg DIBP x 0.53) + (3.40 [ig/kgDINP x 0.21)
Step 3: Calculate MOEs for DCHP Exposures andfor Each Phthalate Exposure Included in the
Cumulative Scenario
Next, MOEs are calculated for each exposure of interest that is included in the cumulative scenario
using Equation 4-7. For example, this step involves calculating MOEs for inhalation and dermal DCHP
exposures expressed in index chemical equivalents for each individual COU/OES in Step 1, and an
MOE for non-attributable cumulative phthalate exposure from Step 2 above.
Equation 4-7. Calculating MOEs for Exposures of Interest for Use in the RPF and Cumulative
Approaches
Index Chemical (DBP) POD
MO Ei =
Exposurex in DBP Equivalents
Where:
MOE\ (unitless) = The MOE calculated for each exposure of interest included
in the cumulative scenario.
Index chemical (DBP) POD = The POD selected for the index chemical, DBP. The index
chemical POD is 2,100 |ig/kg (Section 4.4.1).
Exposurei = The exposure estimate in DBP equivalents for the pathway
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of interest (i.e., from Step 1 or 2 above).
Example: Using Equation 4-7, the MOEs for inhalation and dermal DCHP exposure estimates for the
Application of paints and coatings (solids) OES in DBP equivalents from Step 1 and the MOE for the
non-attributable cumulative exposure estimate in DBP equivalents from sSep 2 are 33, 610, and 407,
respectively.
ttnr? Ann 2,100 [ig/kg
MOEcumuiative n on-attributable ~ 407 — —
5.16 |ig/kg
2,100 \ig/kg
MOEcou_Inhaiat ion = 32.7 = —
64.2 |ig/kg
2,100 \ig/kg
MOEcou_Dermal = 610 = 0 „ „
cou Dermal 3.44\ig/kg
Step 4: Calculate the Cumulative MOE
For the cumulative MOE approach, MOEs for each exposure of interest in the cumulative scenario are
first calculated (Step 3). The cumulative MOE for the cumulative scenario can then be calculated using
Equation 4-8, which shows the addition of MOEs for the inhalation and dermal exposures routes from
an individual DCHP COU as well as the MOE for non-attributable cumulative exposure to phthalates
from NHANES urinary biomonitoring and reverse dosimetry. Additional MOEs can be added to the
equation as necessary (e.g., for the ingestion route for consumer scenarios).
Equation 4-8. Cumulative Margin of Exposure Calculation
1
Cumulative MOE = z z z
+ T77TF + '
MOEcou-jnhdidtign MOEcou_Dermai MOilcujnujative-Non-attrt&uta&ie
Example: The cumulative MOE for the Application of paints and coatings (solids) OES is 28.9 and is
calculated by summing the MOEs for each exposure of interest from Step 3 as follows:
1
Cumulative MOE = 28.9 = —: ^ -r—
+ + '
32.7 1 610 1 407
4A.4 Risk Estimates for Workers Based on Relative Potency
This section summarizes RPF analysis risk estimates for female workers of reproductive age from acute
duration exposures to DCHP. In the RPF analysis, EPA focused its occupational risk assessment on this
population and exposure duration because as described in Section 4.4 and (U.S. EPA. 2024ah). this
population and exposure duration is considered most directly applicable to the common hazard outcome
that serves as the basis for the RPF analysis (i.e., reduced fetal testicular testosterone).
To evaluate cumulative risk to female workers of reproductive age, EPA combined inhalation and
dermal exposures to DCHP from each individual occupational COU/OES with non-attributable
cumulative exposure to DEHP, DBP, BBP, DIBP, and DINP (estimated from NHANES urinary
biomonitoring using reverse dosimetry). As described in Section 4.4.3, for each individual phthalate
exposures were scaled by relative potency per chemical, expressed in terms of index chemical (DBP)
equivalents, and summed to estimate cumulative exposure and cumulative risk for each COU. MOEs in
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Table 4-22 are shown both with (cumulative MOE) and without (MOEs for individual DCHP COU
derived using the RPF analysis) the addition of non-attributable cumulative exposure (estimated from
NHANES using reverse dosimetry) so that MOEs scaled by relative potency can be compared.
Table 4-22 summarizes the acute duration central tendency and high-end MOEs for female workers of
reproductive age used to characterize cumulative risk from exposure to DCHP, DEHP, DBP, BBP,
DIBP, and DINP, as well as DCHP MOEs scaled by relative potency without non-attributable
cumulative exposure (i.e., NHANES) included. MOE calculations are also provided in the Draft
Occupational and Consumer Cumulative Risk Calculator for Dicyclohexyl Phthalate (DCHP) (U.S.
EPA. 2024y). As discussed in Section 4.3.2, high-end acute MOEs for female workers of reproductive
age were below the benchmark of 30 for all DCHP COUs/OES evaluated as part of the individual
chemical assessment. Addition of non-attributable cumulative national exposure (from NHANES)
would have no influence on high-end risk conclusions. Therefore, EPA focused its cumulative risk
characterization on central tendency MOEs (none of which were <30 in the individual DCHP
assessment in Section 4.3.2). For all COUs, the Agency presents MOEs for each individual exposure
route. That is, MOEs resulting from inhalation and dermal DCHP exposures for each COU/OES scaled
to index chemical (DBP) equivalents (i.e., the RPF analysis) as well as cumulative occupational
exposure (i.e., aggregate exposure to DCHP from a single COU [in index chemical equivalents]
combined with cumulative national exposure [in index chemical equivalents]), so that the contribution of
each exposure to the cumulative MOE can be discerned.
COUs/OES with Cumulative MOEs Ranging from 34 to 244
As can be seen from Table 4-22, cumulative acute central tendency MOEs ranged from 34 to 244 for
COUs covered under 12 of the OESs evaluated for DCHP, including the following:
• Import and repackaging (cumulative MOE = 55);
• PVC plastics compounding (cumulative MOE = 34);
• PVC plastics converting (cumulative MOE = 65);
• Non-PVC materials compounding (cumulative MOE = 52);
• Non-PVC materials converting (cumulative MOE = 110);
• Application of adhesives and sealants (liquids) (cumulative MOE = 244);
• Application of adhesives and sealants (solids) (cumulative MOE = 49);
• Use of laboratory chemicals (liquids) (cumulative MOE = 244);
• Use of laboratory chemicals (solids) (cumulative MOE = 40);
• Recycling (cumulative MOE = 63);
• Fabrication or use of final products and articles (cumulative MOE = 72); and
• Waste handling, treatment, and disposal (cumulative MOE = 63).
COUs/OES with Cumulative MOEs Ranging from 18 to 29
As can be seen from Table 4-22, cumulative acute central tendency MOEs ranged from 18 to 29 for
COUs covered under six OES, including:
• Manufacturing (cumulative MOE = 18);
• Incorporation into other formulations, mixtures, or reaction products (cumulative MOE = 18);
• Incorporation into adhesives and sealants (cumulative MOE = 18);
• Incorporation into paints and coatings (cumulative MOE = 18);
• Application of paints and coatings - liquids (cumulative MOE = 20); and
• Application of paints and coatings - solids (cumulative MOE = 29).
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EPA characterizes these preceding six OESs as part of the individual chemical assessment in Section
4.3.2. The central tendency acute aggregate MOE from exposure to DCHP alone for female workers of
reproductive age is 35 for four of the six OESs showing cumulative risk (i.e., Manufacturing;
Incorporation into other formulations, mixtures, or reaction products; Incorporation into adhesives and
sealants; and Incorporation into paints and coatings) (Table 4-14), while the cumulative MOE for these
four OES is 18 (Table 4-22). For one OES (Application of paints and coatings - liquids), the central
tendency acute aggregate MOE from exposure to DCHP alone for female workers of reproductive age is
40 (Table 4-14), while the cumulative MOE for this OES is 20 (Table 4-22). For the sixth OES
(Application of paints and coatings - solids), the central tendency acute aggregate MOE from exposure
to DCHP alone for female workers of reproductive age is 60 (Table 4-14), while the cumulative MOE
for this OES is 29 (Table 4-22).
For all of the evaluated OESs, including these six OESs, three factors contribute to the lower cumulative
MOEs compared to the acute aggregate central tendency MOE for female workers of reproductive age:
Scaling by Relative Potency: DCHP inhalation and dermal exposures for the six OESs were scaled by
relative potency to the index chemical. The RPF for DCHP is 1.66, which means DCHP exposures when
multiplied by the RPF and expressed in terms of index chemical (DBP) equivalents, increased by 66
percent. This 66 percent increase in exposure expressed in terms of index chemical equivalents is the
primary factor leading to lower cumulative MOEs. RPFs used to scale for relative potency were
calculated based on a common hazard endpoint (i.e., reduced fetal testicular testosterone) from data
from multiple studies evaluating effects of phthalates on fetal testicular testosterone using a meta-
analysis and BMD modeling approach for each of the six phthalates included in the cumulative chemical
group (see (U.S. EPA. 2024ah) for further details). This analysis provides a robust basis for assessing
the dose-response for the common hazard endpoint (i.e., reduced fetal testicular testosterone) across the
six toxicologically similar phthalates included in the cumulative assessment. For example, use of meta-
analysis and BMD modeling allowed EPA to utilize more fetal testicular testosterone data in the low-
end range of the dose-response curve to gain a better understanding of the hazards of DCHP at the low-
end range of the dose-response curve compared to the index chemical, DBP. Overall, EPA has robust
confidence in the draft RPFs used in this CRA (Section 4.4.4.1).
Index Chemical POD: As described previously in Sections 4.4.1 and 4.4.3, cumulative MOEs are
calculated by dividing the cumulative exposure estimate expressed in terms of index chemical (DBP)
equivalents by the index chemical POD. The POD for the index chemical (DBP) used to calculate
cumulative risk is 2.1 mg/kg (based on a BMDLs for reduced fetal testicular testosterone).
Comparatively, the DCHP POD used to calculate MOEs for individual DCHP COUs in Section 4.3.2 is
2.4 mg/kg (based on a NOAEL for phthalate syndrome-related effects). The index chemical (DBP) POD
is 12.5 percent lower (i.e., more sensitive) than the individual DCHP POD, which contributes to the
lower cumulative MOEs. Overall, EPA has robust confidence in the index chemical (DBP) POD used in
this CRA. This is because the POD is based on fetal testicular testosterone data from eight publications
that was integrated via meta-analysis and BMD modeling. Notably, several of the available studies
evaluated effects on fetal testicular testosterone at dose levels in the low-end range of the dose response
curve (i.e., 1, 10, 33, and 50 mg/kg-day) where the BMDs (14 mg/kg-day) and BMDLs (9 mg/kg-day)
were derived (see (U.S. EPA. 2024ah) for further details).
Addition of Non-attributable Cumulative Exposure: As part of its CRA, EPA calculated non-attributable
cumulative exposure to DEHP, DBP, BBP, DIBP, and DINP using NHANES urinary biomonitoring
data from the 2017 to 2018 survey (most recent data set available) and reverse dosimetry (see Section
4.4.2 and (U.S. EPA. 2024ah) for further details), representing exposure to a national population. DCHP
was not included as part of the cumulative non-attributable national exposure estimate because DCHP
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has not been included in NHANES analyses since 2011 due to low frequencies of detection and low
detection levels in urine (Section 4.4.2). Non-attributable cumulative exposure estimates were scaled by
relative potency and expressed in index chemical (DBP) equivalents. Non-attributable cumulative
exposure was then combined with acute inhalation and dermal DCHP exposures for each individual
COU/OES scaled by relative potency. For female workers of reproductive age, EPA added a non-
attributable cumulative exposure of 5.16 |ig/kg index chemical (DBP) equivalents to calculate the
cumulative MOE. This non-attributable cumulative exposure estimate is the 95th percentile estimate for
black non-Hispanic women of reproductive age (16 to 49 years). This non-attributable cumulative
exposure contributes approximately 7.4 percent to the risk cap with a benchmark MOE of 30.
Overall, EPA has robust confidence in the non-attributable cumulative exposure estimate since it was
calculated from CDC's NHANES biomonitoring data set, which provides a statistically representative
sampling of the U.S. civilian population. Furthermore, the Agency used a well-established reverse
dosimetry approach to calculate phthalate daily intake values from urinary biomonitoring data.
For five out of the six OESs showing cumulative risk (i.e., Manufacturing; Incorporation into other
formulations, mixtures, or reaction products; Incorporation into adhesives and sealants; Incorporation
into paints and coatings; and Application of paints and coatings - liquids), scaling acute inhalation
exposures by relative potency alone led to acute inhalation MOEs below 30, ranging from 19 to 22,
whereas the acute cumulative MOE (DCHP OES + cumulative non-attributable) ranged from 18 to 20.
For one OES showing cumulative risk (i.e., Application of paints and coatings - solids), the acute
aggregate MOE based on exposure to DCHP expressed in index chemical equivalents was 31 and
adding non-attributable cumulative exposure resulted in a cumulative MOE of 29.
4.4.4.1 Overall Confidence in Cumulative Worker Risk Estimates
EPA has robust confidence in the RPFs and index chemical POD used to calculate the RPF analysis and
cumulative MOEs. To derive RPFs and the index chemical POD, the Agency integrated data from
multiple studies evaluating fetal testicular testosterone using a meta-analysis approach and conducted
BMD modeling. This meta-analysis and BMD modeling approach represents a refinement of the
NOAEL/LOAEL approach used in the individual DCHP assessment and therefore increases EPA's
confidence in risk estimates. Finally, the Agency has robust confidence in the non-attributable
cumulative exposure estimates for DEHP, DBP, BBP, DIBP, and DINP derived from NHANES urinary
biomonitoring data using reverse dosimetry.
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3371 Table 4-22. Risk Summary Table for Female Workers of Reproductive Age Using the RPF Analysis
Life Cycle Stage/
Category
Subcategory
OES
Exposure
Level
Acute MOEs for Female Workers of Reproductive Age
(Benchmark = 30)
Inhalation MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Dermal MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Aggregate
MOE (DCHP
COU;
Exposure in
DBP
Equivalents)
Cumulative MOE
(Aggregate DCHP
MOE +
Cumulative Non-
attributable) "
Manufacturing -
Domestic manufacturing
Domestic manufacturing
Manufacturing
CT
19.1
610
18.5
17.7
HE
1.8
305
1.8
1.8
Manufacturing -
Importing
Importing
Import and
Repackaging
CT
70
610
63
55
Processing -
Repackaging
Repackaging (e.g., laboratory
chemicals)
HE
3.1
305
3.0
3.0
Processing - Processing
- incorporation into
formulation, mixture, or
reaction product
Plasticizer in:
- Adhesive manufacturing
Adhesive and sealant chemicals
in:
- Adhesive manufacturing
Stabilizing Agent in:
- Adhesive manufacturing
Incorporation into
adhesives and
sealants
CT
19.1
610
18.5
17.7
HE
1.8
305
1.8
1.8
Processing - Processing
- incorporation into
formulation, mixture, or
reaction product
Plasticizer in:
- Paint and coating
manufacturing
- Printing ink manufacturing
Stabilizing agent in:
- Paint and coating
manufacturing
Incorporation into
paints and coatings
CT
19.1
610
18.5
17.7
HE
1.8
305
1.8
1.8
Processing - Processing
- incorporation into
formulation, mixture, or
reaction product
Stabilizing agent in:
Asphalt paving, roofing, and
coating materials manufacturing
Incorporation into
other formulations,
mixtures, and
reaction products not
covered elsewhere
CT
19.1
610
18.5
17.7
HE
1.8
305
1.8
1.8
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Life Cycle Stage/
Category
Subcategory
OES
Exposure
Level
Acute MOEs for Female Workers of Reproductive Age
(Benchmark = 30)
Inhalation MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Dermal MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Aggregate
MOE (DCHP
COU;
Exposure in
DBP
Equivalents)
Cumulative MOE
(Aggregate DCHP
MOE +
Cumulative Non-
attributable) "
Processing - Processing
- incorporation into
formulation, mixture, or
reaction product
Plasticizer in:
- Plastic material and resin
manufacturing
- Plastics product
manufacturing
PVC plastics
compounding
CT
40
610
37
34
HE
1.9
305
1.9
1.9
Stabilizing agent in:
-Plastics product manufacturing
Processing - Processing
- incorporation into
article
Plasticizer in:
- Plastics product
manufacturing
PVC plastics
converting
CT
89
610
77
65
HE
4.3
305
4.3
4.2
Processing - Processing
- incorporation into
formulation, mixture, or
reaction product
Plasticizer in:
- Plastics product
manufacturing
- Rubber product
manufacturing
- Plastic material and resin
manufacturing
Non-PVC material
compounding
CT
66
610
60
52
HE
3.2
305
3.2
3.2
Stabilizing agent in:
-Plastics product manufacturing
Processing - Processing
- incorporation into
article
Plasticizer in:
- Plastics product
manufacturing
- Rubber product
manufacturing
Non-PVC material
converting
CT
199
610
150
110
HE
9.7
305
9.4
9.2
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Acute MOEs for Female Workers of Reproductive Age
(Benchmark = 30)
Life Cycle Stage/
Category
Subcategory
OES
Exposure
Level
Inhalation MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Dermal MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Aggregate
MOE (DCHP
COU;
Exposure in
DBP
Equivalents)
Cumulative MOE
(Aggregate DCHP
MOE +
Cumulative Non-
attributable) "
Industrial Use -
Finishing agent
Cellulose film production
CT
21.7
610
21.0
19.9
Industrial Use - Inks,
Inks, toner, and colorant
toner, and colorant
products
products (e.g., screen printing
ink)
Application of paints
and coatings -
liquids
HE
1.0
305
1.0
1.0
Commercial Use - Inks,
toner, and colorant
products
Inks, toner, and colorant
products (e.g., screen printing
ink)
Industrial Use - Paints
and coatings
Paints and coatings
Commercial Use - Paints
and coatings
Paints and coatings
Industrial Use -
Finishing agent
Cellulose film production
CT
32.7
610
31.1
28.9
Industrial Use - Inks,
Inks, toner, and colorant
toner, and colorant
products
products (e.g., screen printing
ink)
HE
1.9
305
1.9
1.8
Commercial Use - Inks,
toner, and colorant
products
Inks, toner, and colorant
products (e.g., screen printing
ink)
Application of paints
and coatings - solids
Industrial Use - Paints
and coatings
Paints and coatings
Commercial Use - Paints
and coatings
Paints and coatings
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Life Cycle Stage/
Category
Subcategory
OES
Exposure
Level
Acute MOEs for Female Workers of Reproductive Age
(Benchmark = 30)
Inhalation MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Dermal MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Aggregate
MOE (DCHP
COU;
Exposure in
DBP
Equivalents)
Cumulative MOE
(Aggregate DCHP
MOE +
Cumulative Non-
attributable) "
Industrial Uses -
Adhesives and sealants
Adhesives and sealants (e.g.,
computer and electronic product
manufacturing; transportation
equipment manufacturing)
Application of
adhesives and
sealants - liquids
CT
610
244
HE
305
174.3
Commercial Uses -
Adhesives and sealants
Adhesives and sealants
Industrial Uses -
Adhesives and sealants
Adhesives and sealants in (e.g.,
computer and electronic product
manufacturing; transportation
equipment manufacturing)
Application of
adhesives and
sealants - solids
CT
61
610
56
49
HE
3.4
305
3.4
3.3
Commercial Use -
Laboratory chemicals
Laboratory chemicals
Use of laboratory
chemicals - liquid
CT
-
610
-
244
HE
-
305
-
174.3
Commercial Use -
Laboratory chemicals
Laboratory chemicals
Use of laboratory
chemicals - solid
CT
48
610
45
40
HE
3.4
305
3.4
3.3
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Life Cycle Stage/
Category
Subcategory
OES
Exposure
Level
Acute MOEs for Female Workers of Reproductive Age
(Benchmark = 30)
Inhalation MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Dermal MOE
(DCHP COU;
Exposure in
DBP
Equivalents)
Aggregate
MOE (DCHP
COU;
Exposure in
DBP
Equivalents)
Cumulative MOE
(Aggregate DCHP
MOE +
Cumulative Non-
attributable) "
Industrial Use - Other
articles with routine
direct contact during
normal use including
rubber articles; plastic
articles (hard)
Other articles with routine
direct contact during normal use
including rubber articles; plastic
articles (hard) (e.g.,
transportation equipment
manufacturing)
Fabrication or use of
final products or
articles
CT
102
610
87
72
Commercial Use -
Building/construction
materials not covered
elsewhere
Building/construction materials
not covered elsewhere
HE
11.3
305
10.9
10.6
Commercial Use - Other
articles with routine
direct contact during
normal use including
rubber articles; plastic
articles (hard)
Other articles with routine
direct contact during normal use
including rubber articles; plastic
articles (hard)
Processing - Recycling
Recycling
Recycling
CT
85
610
74
63
HE
5.8
305
5.7
5.6
Disposal - Disposal
Disposal
Waste handling,
treatment and
disposal
CT
85
610
74
63
HE
5.8
305
5.7
5.6
" The acute cumulative MOE is derived by summing inhalation exposure from each individual DCHP COU with dermal exposure from the same DCHP COU and the
cumulative non-attributable exposure to DEHP, DBP, BBP, DIBP, and DINP. Non-attributable cumulative exposure was estimated from NHANES urinary
biomonitoring data using reverse dosimetry. All exposure estimates were (1) scaled by relative potency, (2) expressed in index chemical equivalents (i.e., DBP
equivalents), (3) summed to calculate cumulative exposure in index chemical equivalents, and then (4) compared to the index chemical POD (i.e., HED of 2.1 mg/kg-
day) to calculate the cumulative MOE.
3372
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4.4.5 Risk Estimates for Consumers Based on Relative Potency
This section summarizes cumulative risk estimates for consumers from acute duration exposures to
DCHP. EPA focused its CRA on women of reproductive age and male infants and children. EPA
focused its consumer CRA on these populations for the acute exposure duration because, as described in
Section 4.2 and (U.S. EPA. 2024ah). these populations and exposure duration are considered most
directly applicable to the common hazard outcome that serves as the basis for the cumulative assessment
{i.e., reduced fetal testicular testosterone). For consumers, EPA did not specifically evaluate women of
reproductive age or male infants and children; however, consumer exposures of teenagers (16-20 years)
and adults (21+ years) were considered a proxy for women of reproductive age, while infants (<1 year),
toddlers (1-2 years), children (3-5 and 6-10 years), and young teens (11-15 years) were considered a
proxy for male infants and children.
After scaling high-intensity DCHP acute exposure estimates from individual COUs by relative potency
and adding non-attributable cumulative exposure (calculated from NHANES) from DEHP, DBP, BBP,
DIBP, and DINP, all high-intensity consumer COUs product and article examples had cumulative
MOEs above the benchmark of 30, ranging from 130 for acute infant exposure through outdoor seating
to 455 for acute exposure to adhesives for small repairs for young teens (11-15 years) (Table 4-23).
4.4.5.1 Overall Confidence in Cumulative Consumer Risks
As discussed in Section 4.3.3, EPA has moderate to robust confidence in all of the exposure estimates
for the evaluated consumer product scenarios. The Agency has robust confidence in the RPFs and index
chemical POD used to calculate the cumulative MOEs. To derive RPFs and the index chemical POD,
EPA integrated data from multiple studies evaluating fetal testicular testosterone using a meta-analysis
approach and conducted BMD modeling. This meta-analysis and BMD modeling approach represents a
refinement of the NOAEL/LOAEL approach used in the individual DCHP assessment and therefore
increases EPA's confidence in risk estimates. Finally, EPA has robust confidence in the non-attributable
cumulative exposure estimates for DEHP, DBP, BBP, DIBP, and DINP derived from NHANES urinary
biomonitoring data using reverse dosimetry.
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3400 Table 4-23. Consumer Cumulative Risk Summary Table
Life Cycle Stage: COU:
Subcategory
Product or Article
Duration
Exposure
Scenario
(H, M, L) a
Exposure Scenario
Lifestage (Years)
MOE (Based on All Exposures in Index Chemical Equivalents)
(Benchmark MOE = 30)
Infant
(<1 Year)
Toddler
(1-2
Years)
Preschooler
(3-5 years)
Middle
Childhood
(6-10
years)
Young
Teen
(11-15
years)
Teenager
(16-20
years)
Adult
(21+
years)
Consumer Uses: Adhesives and
sealants: Adhesives and sealants
Adhesives for small
repairs
Acute
H
Cumulative
(Aggregate DCHP
COU + Cumulative
Non-attributable)
455
389
388
Consumer Uses: Adhesives and
sealants: Adhesives and sealants
Automotive adhesives
Acute
H
Cumulative
(Aggregate DCHP
COU + Cumulative
Non-attributable)
191
191
192
282
437
377
377
Consumer Uses: Other articles
with routine direct contact
during normal use including
rubber articles; plastic articles
(hard)
Small articles with
potential for semi-
routine contact: labels,
nitrocellulose;
ethylcellulose;
chlorinated rubber;
PVAc; PVC
Acute
H
Cumulative
(Aggregate DCHP
COU + Cumulative
Non-attributable)
165
169
172
248
400
351
348
Consumer Uses: Consumer
articles that contain
dicyclohexyl phthalate from:
Inks, toner, and colorants;
Paints and coatings; Adhesives
and sealants (e.g., paper
products, textiles, products
using cellulose film, etc.)
Outdoor seating
Acute
H
Cumulative
(Aggregate DCHP
COU + Cumulative
Non-attributable)
130
136
142
199
305
281
275
Consumer Uses: Consumer
articles that contain
dicyclohexyl phthalate from:
Inks, toner, and colorants;
Paints and coatings; Adhesives
and sealants (e.g., paper
products, textiles, products
using cellulose film, etc.)
Small articles with the
potential for semi-
routine contact: labels,
and packaging
adhesives, foil and
cellophane lacquers, and
printing inks
Acute
H
Cumulative
(Aggregate DCHP
COU + Cumulative
Non-attributable)
165
169
172
248
400
351
348
Consumer Uses: Consumer
articles that contain
dicyclohexyl phthalate from:
Inks, toner, and colorants;
Paints and coatings; Adhesives
and sealants (e.g., paper
Electronics containing
dye adhesive
Exposures not expected. Identified in dye attach adhesive used in wirebond packaging for semiconductor devices or in
automotive cameras. As the adhesive is used in small quantities and contained within the electronic articles, no exposures are
expected during potential use of these items.
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Life Cycle Stage: COU:
Subcategory
Product or Article
Duration
Exposure
Scenario
(H, M, L)«
Exposure Scenario
Lifestage (Years)
MOE (Based on All Exposures in Index Chemical Equivalents)
(Benchmark MOE = 30)
Infant
(<1 Year)
Toddler
(1-2
Years)
Preschooler
(3-5 years)
Middle
Childhood
(6-10
years)
Young
Teen
(11-15
years)
Teenager
(16-20
years)
Adult
(21+
years)
products, textiles, products
using cellulose film, etc.)
"Exposure scenario intensities include high (H), medium (M), and low (L).
4 Bystander scenarios
c Indoor scenario
3401
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3405
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3410
3411
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3414
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3418
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4,4.6 Cumulative Risk Estimates for the General Population
For DCHP, EPA did not evaluate cumulative risk for the general population from environmental
releases. As discussed in Section 4.1.3, the Agency employed a screening4evel approach to assess risk
from exposure to DCHP for the general population from environmental releases. Using this conservative
screening-level approach, EPA did not identify any pathways of concern, indicating that refinement was
not necessary.
4.5 Comparison of Single Chemical and Cumulative Risk Assessments
In support of the developed CRA, EPA has relied substantially on existing CRA-related work by the
Agency's Risk Assessment Forum (RAF), EPA Office of Pesticide Programs (OPP), the Organisation
for Economic Co-operation and Development (OECD), the European Commission, and the World
Health Organization (WHO) and International Programme on Chemical Safety (IPCS), including
• Guidelines for the Health Risk Assessment of Chemical Mixtures (U.S. EPA. 1986);
• Guidance for Identifying Pesticide Chemicals and Other Substances that Have a Common
Mechanism of Toxicity (U.S. EPA. 1999);
• Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures (U.S.
EPA. 2000);
• General Principles for Performing Aggregate Exposure and Risk Assessments (U.S. EPA. 2001);
• Guidance on Cumulative Risk Assessment of Pesticide Chemicals that Have a Common
Mechanism of Toxicity (U.S. EPA. 2002a);
• Framework for Cumulative Risk Assessment (U.S. EPA. 2003);
• Concepts, Methods and Data Sources for Cumulative Health Risk Assessment of Multiple
Chemicals, Exposures, and Effects: A Resource Document (U.S. EPA. 2007);
• Pesticide Cumulative Risk Assessment: Framework for Screening Analysis Purpose (U.S. EPA.
2016b);
• Advances in Dose Addition For Chemical Mixtures: A White Paper (U.S. EPA. 2023 a).
• Phthalates and Cumulative Risk Assessment: The Tasks Ahead (NRC. 2008);
• State of the Art Report on Mixture Toxicity (European Commission. 2009);
• Risk Assessment of Combined Exposure to Multiple Chemicals: A WHO IPCS Framework (Meek
et al.. 2011); and
• Considerations for Assessing the Risks of Combined Exposure to Multiple Chemicals (OECD.
2018).
Herein, EPA has evaluated risks for workers (Section 4.3.2), consumers (Section 4.3.3), and the general
population (Section 4.3.4) from exposure to DCHP alone, as well as cumulative risks for workers
(Section 4.4.4) and consumers (Section 4.4.5) that take into account differences in relative potency and
cumulative non-attributable exposure to DEHP, DBP, BBP, DIBP, and DINP from NHANES
biomonitoring and reverse dosimetry.
There are several notable differences between the individual DCHP assessment (Section 4.3) and the
CRA (Section 4.4). As part of the individual DCHP assessment (Section 4.3), EPA considered all human
health hazards of DCHP and selected a POD based on a NOAEL for phthalate syndrome-related effects
to characterize risk from exposure to DCHP. As part of its exposure assessment in the individual DCHP
assessment, EPA considered acute, intermediate, and chronic exposures durations for a broad range of
populations—including female workers of reproductive age, average adult workers, ONUs, the general
population, and consumers of various lifestages (e.g., infants, toddlers, children, adults). Furthermore, in
the individual DCHP assessment, EPA evaluated inhalation and dermal exposures to workers, as well as
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consumer exposure to DCHP via the inhalation, dermal, and ingestion exposure routes. In contrast, the
CRA is more focused in scope (Section 4.4). First, the CRA is based on a uniform measure of hazard
{i.e., reduced fetal testicular testosterone) that serves as the basis for deriving RPFs and the index
chemical (DBP) POD, which were derived via meta-analysis and BMD modeling (Section 4.4.1).
Second, the CRA is focused on acute duration exposures and the most sensitive populations (i.e., women
of reproductive age, male infants, male children) (Section 4.4). Finally, for the CRA, DCHP exposures
from individual consumer and worker COUs were (1) scaled by relative potency; (2) expressed in index
chemical (DBP) equivalents; and (3) combined with non-attributable cumulative exposure to DEHP,
DBP, BBP, DIBP, and DINP from NHANES.
Both the individual DCHP assessment (Section 4.3) and the CRA (Section 4.4) led to similar
conclusions regarding risk estimates for consumers. As discussed in Section 4.3.3, high-intensity MOEs
for consumer scenarios ranged from 740 to 950,000 in the individual DCHP assessment (Benchmark =
30), while cumulative consumer MOEs ranged from 130 to 455 (cumulative Benchmark = 30) (Section
4.4.5).
For workers, cumulative acute central tendency MOEs ranged from 18 to 29 for COUs covered under
six OESs (Section 4.4.5). Comparatively, these same six OESs had aggregate acute MOEs that ranged
from 35 to 60 in the individual DCHP assessment (Section 4.3.2). Overall, there are three primary
factors that influenced differences in risk estimates between the individual DCHP assessment (Section
4.3) and the RPF analysis (Section 4.4), which are described below:
• Scaling by Relative Potency. DCHP inhalation, dermal, and ingestion exposures from individual
COUs/OES were scaled by relative potency to the index chemical. The RPF for DCHP is 1.66,
which means DCHP exposures when multiplied by the RPF and expressed in terms of index
chemical (DBP) equivalents, increased by 66 percent. This increase in exposure expressed in
terms of index chemical equivalents is the primary factor leading to lower cumulative MOEs.
• Index Chemical POD. Cumulative MOEs are calculated by dividing the index chemical POD by
a cumulative exposure estimate expressed in terms of index chemical (DBP) equivalents. The
POD for the index chemical (DBP) used to calculate cumulative risk is 2.1 mg/kg (based on a
BMDL5 for reduced fetal testicular testosterone). Comparatively, the DCHP POD used to
calculate MOEs for individual DCHP COUs is 2.4 mg/kg (based on a NOAEL for phthalate
syndrome-related effects). The index chemical (DBP) POD is 12.5 percent lower (i.e., more
sensitive) than the individual DCHP POD, which contributes to the lower cumulative MOEs.
• Addition of Non-attributable Cumulative Exposure. As part of its CRA, EPA calculated non-
attributable cumulative exposure to DEHP, DBP, BBP, DIBP, and DINP using NHANES urinary
biomonitoring data from the 2017 to 2018 survey reverse dosimetry (Section 4.4.2), representing
exposure to a national population. Overall, this non-attributable cumulative exposure contributes
approximately 7.4 to 15.5 percent to the risk cap, depending on the population and age group.
Ultimately, the impact of scaling by relative potency has a significant impact on the risk estimates for
exposure to DCHP alone. There is little additional cumulative risk by adding the simultaneous exposure
of other phthalates to the single chemical risk estimates for DCHP (i.e., non-attributable cumulative
exposure from NAHNES adds 7.4-15.5% to the risk cup).
EPA has robust confidence in its CRA and moderate to robust confidence in its individual assessment of
DCHP for workers (Section 4.3.2.1), consumers (Section 4.3.3.1), and the general population (Section
4.3.4.1). RPFs used to scale for relative potency were calculated based on a common hazard endpoint
(i.e., reduced fetal testicular testosterone) from data from multiple studies evaluating effects of
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3494 phthalates on fetal testicular testosterone using a meta-analysis and BMD modeling approach for each of
3495 the six phthalates included in the cumulative chemical group (U.S. EPA. 2024ah). This analysis provides
3496 a robust basis for assessing the dose-response for the common hazard endpoint (i.e., reduced fetal
3497 testicular testosterone) across the six toxicologically similar phthalates included in the CRA. For
3498 example, use of meta-analysis and BMD modeling allowed EPA to utilize more fetal testicular
3499 testosterone data in the low-end range of the dose-response curve to gain a better understanding of the
3500 hazards of DCHP at the low-end range of the dose-response curve compared to the index chemical,
3501 DBP.
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3502 5 ENVIRONMENTAL RISK ASSESSMENT
3503
DCHP - Environmental Risk Assessment (Section 5):
Key Points
EPA evaluated the reasonably available information to support the environmental risk assessment of
DCHP. The key points of the environmental risk assessment are summarized below:
• DCHP is expected to be released to the environment via air, water, biosolids, and disposal to
landfills. Based on DCHP's fate parameters, concentrations of DCHP in soil and groundwater
resulting from releases to the landfill or via biosolids were not quantified but discussed
qualitatively because DCHP is not expected to be persistent or be mobile in soils (Section 2).
• High-end concentrations of DCHP in surface water were estimated for the purpose of risk
assessment for environmental exposure. The only two OESs with estimated water releases were
Plastic compounding and Recycling, with Plastic compounding being the highest release and
subsequent environmental concentrations in surface water (Section 3 and (U.S. EPA. 2024p)).
• The physical and chemical properties of DCHP indicate that it has low bioaccumulation
potential and is unlikely to biomagnify. Therefore, EPA did not analyze the trophic transfer of
DCHP through dietary exposures to aquatic organisms (U.S. EPA. 2024p).
• EPA derived a concentration of concern (COC) for reproductive effects of chronic DCHP water
exposure of 32 jag/L DCHP to an aquatic invertebrate, Daphnia magna (U.S. EPA. 2024o).
Empirical toxicity data for laboratory rats were used to estimate a terrestrial mammal hazard
threshold of 179.3 mg/kg bw/d DCHP (U.S. EPA. 2024o).
• EPA found no reasonably available definitive environmental hazard data for DCHP exposures to
birds, reptiles, sediment-dwelling animals, terrestrial invertebrates, or plants (U.S. EPA. 2024o).
Therefore, DCHP hazards to these organisms were not assessed.
• Based on qualitative risk characterization, EPA does not expect risk for any assessed pathways
for exposure of DCHP to terrestrial organisms. Risk is not expected because exposure to
terrestrial organisms in water, soil, air, and diet is expected to be low (Section 2) and no
evidence of DCHP hazard to wild terrestrial organisms was reasonably available (Section 5.2).
EPA considered DCHP hazard to laboratory rodents in lieu of reasonably available wild
mammal hazard resulting in conservative dietary mammal exposures being at least an order of
magnitude lower than the hazard threshold (Section 5.3). The Agency has robust confidence in
the preliminary determination of no risk to terrestrial organisms.
• Based on qualitative risk characterization, EPA does not expect risk for acute durations of
DCHP exposure to aquatic organisms because reasonably available data found no acute hazard
effects up to and above the estimated upper bound of the range of probable water solubility
limits (1,480 ng/L) (Section 5.3).
• Based on qualitative risk characterization, EPA does not expect risk of chronic DCHP exposure
to aquatic animals. Considerable uncertainties exist about the limit of water solubility, water
release estimates, and low flow surface water modeling estimates. No risk was indicated under
scenarios of lower limits of water solubility, lower release estimates, more rapid stream flow,
and available measured DCHP water concentrations from the literature.
3504 5.1 Summary of Environmental Exposures
3505 EPA assessed environmental concentrations of dicyclohexyl phthalate (DCHP) in air, water, and land
3506 (soil, biosolids, and groundwater) for use in environmental exposure. The environmental exposures are
3507 described in the Draft Physical Chemistry and Fate and Transport Assessment for Dicyclohexyl
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Phthalate (DCHP) (U.S. EPA. 2024z) and the Draft Environmental Media, General Population, and
Environmental Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024p). DCHP
will preferentially sorb into sediments, soils, particulate matter in air, and in wastewater solids during
wastewater treatment. High-quality studies of DCHP biodegradation rates and physical and chemical
properties indicate that DCHP will have limited persistence and mobility in soils receiving biosolids
(U.S. EPA. 2024z). Surface water, pore water, and sediment concentrations of DCHP were modeled
using VVWM-PSC. The PVC plastics compounding COU resulted in the highest estimated release to
water, followed by Recycling. DCHP concentrations in receiving waters were estimated for these COUs
and ranged from 0.057 |ig/L to 165 |ig/L DCHP in the water column in low flow (7Q10) conditions. For
the land pathways, there are uncertainties in the relevance of limited monitoring data for biosolids and
landfill leachate to the COUs considered. However, based on high-quality physical and chemical
property data, EPA determined that DCHP will have low persistence potential and mobility in soils.
Therefore, groundwater concentrations resulting from releases to the landfill or to agricultural lands via
biosolids applications were not quantified but were discussed qualitatively.
Limited measured data were reasonably available from the scientific literature on DCHP concentrations
in soils, biosolids, soils receiving biosolids, and landfills. No monitoring data of DCHP in these
environments were reasonably available. Limited reasonably available information was available related
to the uptake and bioavailability of DCHP soils. Based on the range of estimates of water solubility (30-
1,480 |ig/L) and hydrophobicity (log Kow = 4.82; log Koc = 4.47), DCHP is expected to have low
bioavailability in soil. DCHP has not readily measured or monitored in aquatic or terrestrial organisms
and has low bioaccumulation and biomagnification potential. Therefore, DCHP has low potential for
trophic transfer through food webs. DCHP is expected to have minimal air to soil deposition.
5.2 Summary of Environmental Hazards
EPA evaluated the reasonably available information for environmental hazard endpoints associated with
DCHP exposure to ecological receptors in aquatic and terrestrial ecosystems. The Agency reviewed two
references from the peer-reviewed literature and four studies reported by the Japanese Ministry of the
Environment that were subsequently summarized by EU ECHA. EPA determined all references had
high or medium data quality. These hazards are described in the Draft Environmental Hazard
Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024o).
EPA found limited definitive environmental hazard data for DCHP. The reasonably available studies
found all acute exposure hazards to fish, invertebrates, and algae to be higher than the upper bound of
the range of probable water solubility limits of 1,480 |ig/L DCHP. However, DCHP caused chronic
reproductive effects to an aquatic invertebrate (Daphnia magna) and a fish species (Danio rerio) at
concentrations below the water solubility limit. EPA derived a concentration of concern (COC) for
reproductive effects of chronic DCHP water exposure of 32 |ig/L DCHP.
In terrestrial habitats, the available data suggest that DCHP might cause hazard to terrestrial mammals
through dietary exposures. A hazard effects threshold was estimated based on laboratory rodent
experiments because wild organism hazard studies were not reasonable available. EPA determined a
terrestrial mammal hazard threshold leading to reduced body weight over two generations of dietary
exposure to 179.3 mg/kg bw/d DCHP.
No hazard data were reasonably available for birds, reptiles, terrestrial invertebrates, and plants.
Therefore, these taxa were not assessed.
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5.3 Environmental Risk Characterization
5.3.1 Risk Assessment Approach
The environmental risk characterization of DCHP was conducted to evaluate whether the potential
releases and resultant exposures of DCHP in water, air, or soil will exceed the DCHP concentrations
observed to result in hazardous effects to aquatic or terrestrial organisms. In evaluating the DCHP
exposure concentrations, monitored and modeled DCHP concentrations in surface water were used
quantitatively. Concentrations of DCHP in soil (biosolids, landfills, air deposition) and air is limited or
is not expected to be bioavailable and were used qualitatively. In evaluating the environmental hazard of
DCHP, a weight of evidence approach was used to select hazard threshold concentrations for the
derivation of risk quotients for aquatic organisms. A weight of evidence approach was also used to
select hazard threshold concentrations for a description of risk for terrestrial organisms.
Environmental risk was characterized by calculating risk quotients or RQs (U.S. EPA. 1998; Barnthouse
et al.. 1982). The RQ is defined in Equation 5-1 below.
Equation 5-1. Calculating the Risk Quotient
Predicted Environmental Concentration
^ Hazard Threshold
For aquatic organisms, the "effect level" is a derived COC based on a hazard effects concentration. The
COC used to calculate RQs for aquatic organisms was derived from hazard values resulting from
chronic exposures to DCHP. An RQ equal to 1 indicates that the exposures are the same as the
concentration that causes effects. If the RQ exceeds 1, the exposure is greater than the effect
concentration and risk is indicated. If the RQ is less than 1, the exposure is less than the effect
concentration and risk is not indicated. In this assessment, an initial RQ value was determined only for
surface water exposure to aquatic organisms where the worst-case scenario of release, flow, water
solubility and chronic invertebrate hazard were considered. After further consideration of realistic
conditions and hazards, risk was assessed qualitatively for surface water exposures and all other
pathways.
In addition to modeling, environmental monitoring and biomonitoring data were reviewed and screened
to assess wildlife exposure to DCHP (U.S. EPA. 2024p). EPA qualitatively assessed the trophic transfer
of DCHP through food webs to wildlife using a worst-case scenario and physical and chemical
properties. DCHP is not expected to be persistent in the environment as it is expected to degrade rapidly
under most environmental conditions with delayed biodegradation in low-oxygen media and DCHP's
bioavailability is expected to be limited (U.S. EPA. 2024z). Estimates of the DCHP limit of water
solubility range from 30 to 1,480 jj.g/1, leading to uncertainty about DCHP dissolved in surface water.
DCHP is expected to have low bioaccumulation potential, biomagnification potential, and low potential
for uptake based on a log BCF (bioconcentration factor) of 2.85 and a log BAF (bioaccumulation factor)
of 1.83 (U.S. EPA. 2024p. z).
5.3.2 Risk Estimates for Aquatic and Terrestrial Species
For DCHP, surface water exposure was the only scenario where modeled concentrations could be
compared with a hazard threshold or a COC. Thus, EPA calculated an initial RQ for surface water
DCHP concentration but did not calculate RQs for other scenarios of exposure to organisms. Instead,
because either exposure or hazard effects estimates were not reasonably available for other scenarios,
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environmental risk of DCHP to other organisms was characterized by a qualitative description of risk
(Table 5-1).
Table 5-1. Relevant Exposure Pathway to Receptors and Corresponding Risk Assessment for the
DCHP Environmental Risk Characterization
Exposure Pathway
Receptor
Risk Assessment
Surface water
Chronic exposure to aquatic species
(reduced Daphnia magna reproduction
>21 days)
Qualitative; No risk
Acute exposure: no hazard up to and
above 2,000 |ig/L DCHP to fish
(Oryzias latipes), I), magna, and algae
(Raphidocelis subcapitata)
Qualitative; No risk
Trophic transfer
Terrestrial mammal
Qualitative; No risk
Biosolids
Terrestrial mammal
Qualitative; No risk
Landfills
Terrestrial mammal
Qualitative; No risk
Surface Water
The COC was derived from a study of the hazard effects due to chronic (21-day) aqueous exposures to
the freshwater invertebrate, Daphnia magna (NITE. 2000) and determined to be 32 |ig/L DCHP. The
reasonably available studies on Japanese medaka (Oryzias latipes), IX magna, and the freshwater algae
(Raphidocelis subcapitata) found no aquatic acute exposure hazards up to and above the water solubility
limit of 1,480 |ig/L DCHP (U.S. EPA. 2024oY
EPA found no evidence from monitoring reports or the scientific literature that DCHP occurs in surface
water at the COC of 32 |ig/L. However, EPA modeled surface water release under the most conservative
and least likely scenario from the PVC plastics compounding COU. This conservative model included
(1) the highest modeled release estimate, (2) the lowest 7-day average flow over 10 years from a generic
stream, and (3) the highest modeled estimate of the limit of DCHP water solubility (1,480 |ig/L). These
conditions are unlikely for at least two reasons. First, it combined the highest release from a facility into
a low flow scenario indicative of a small stream. Without site-specific data, EPA does not have evidence
that a high release, small stream combination exists in the Unites States. Second, experimental evidence
suggests that the functional limit of DCHP water solubility may be near the lower EPA estimated range
of 30 |ig/L rather than the upper bound of the estimated range of 1,480 |ig/L. Specifically, two studies
that attempted to find hazard thresholds of DCHP to aquatic organisms report their inability to keep
DCHP in solution above 30 to 50 |ig/L even with the aid of cosolvents (Swedish Chemicals Agency.
2023; Mathieu-Denoncourt et al.. 2016). The VMM-PSC modeled concentrations were 165 |ig/L DCHP
in surface water and 95 |ig/L in porewater over 21 days, which are below the upper bound estimate of
the limit of water solubility of 1,480 |ig/L (U.S. EPA. 2024aa). but over 3 times greater than the lower
bound estimate of the limit of water solubility (30 |ig/L) and the water solubility limit (30 |ig/L)
proposed by the Swedish Chemicals Agency (Swedish Chemicals Agency. 2023).
A first-tier screen computed RQs using the upper bound estimate of water solubility (1,480 |ig/L), the
highest release, and median low flow (7Q10) and the COC (32 |ig/L) over 21 days resulting in a RQ
greater than 1. However, RQs were less than 1 under all other scenarios that considered one or more of
the following surface water scenarios, higher flow rates (e.g., 75th percentile 7Q10), modeled central
tendency release estimates (e.g., 1.11 kg/day), or limits of water solubility at the lower bounded estimate
(30 |ig/L), Additional uncertainty about the first-tier screen RQ is due to the DCHP COC being derived
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from a Daphnia study that found a 12.9 percent reduction in offspring reproduction after two to three
generations of exposure to 572 |ig/L DCHP (NITE, 2000). The exposure concentrations in this
experiment were enhance by the use of dimethylformamide as a cosolvent, which resulted in DCHP
concentrations well above the lower bound estimate of water solubility (30 |ig/L) (NITE. 2000).
Therefore, EPA determined a low likelihood of DCHP persisting in surface waters for a long enough
duration (21 days) to cause chronic hazard in aquatic invertebrates, and thus a preliminary indication of
no risk.
In one available study, DCHP concentrations measured in the water column did not exceed 0.014 |ig/L
(Keil et al.. 2011). Monitoring by the Washington State Department of Ecology resulted in no DCHP
detection above the detection limit (0.05 |ig/L) (WA DOE. 2022). No information is available on the
potential continuous or persistent nature of DCHP in the water column of natural systems or from
specific release sites. Modeled concentrations from the Processing/ PVC plastics compounding
COU/OES release scenarios coupled with low flow conditions predict unlikely conditions for exposure
to exceed COCs. Risk of chronic DCHP exposure to aquatic invertebrates requires surface water
concentrations to be three orders of magnitude greater than those reported in the literature as background
concentration or at a point source (Keil et al.. 2011). Modeled DCHP water concentrations from
recycling release scenarios did not indicate risk even in similar low flow conditions.
Sediment and Pore Water
DCHP is expected to partition primarily to soil and sediment, regardless of the compartment of
environmental release (U.S. EPA. 2024ai). DCHP is not expected to undergo long-range transport and is
expected to be found predominantly in sediments near point sources, with a decreasing trend in sediment
concentrations downstream due to DCHP's strong affinity and sorption potential for organic carbon in
sediment. EPA's maximum modeled concentrations under low flow conditions of 112 mg/kg/d (U.S.
EPA. 2024p) reflect the physical and chemical properties of DCHP and its predicted affinity for
sediment (U.S. EPA. 2024z). but may be overestimated due to conservative parameters and the Variable
Volume Water Model - Point Source Calculator (VVM-PSC) three compartment model. Also, DCHP is
not expected to be persistent in the environment as it is expected to degrade rapidly under most
environmental conditions with delayed biodegradation in low-oxygen media (U.S. EPA. 2024z).
EPA found no evidence from monitoring reports or the scientific literature that DCHP occurs in pore
water at the COC of 32 |ig/L. Porewater DCHP concentrations from VVM-PSC modeling resulted in a
maximum of 93 |ig/L, which exceeded the DCHP limit of solubility (30 |ig/L). EPA found no
reasonably available studies on the hazard effects of DCHP sediment exposures to aquatic organisms
(U.S. EPA. 2024o). Despite this, the Agency considered the COC of DCHP to Daphnia (32 |ig/L) to
indicate chronic exposure hazard effects to sediment dwelling animals. Because of the water solubility
uncertainties described for surface risk to aquatic invertebrates, EPA determined a low likelihood of
DCHP persisting in sediment and pore waters for a long enough duration (21 days) to cause chronic
hazard in aquatic invertebrates, and thus a preliminary indication of no risk.
Air
No studies on the hazardous effects of DCHP inhalation were reasonably available for EPA to review.
Only a few studies that monitored ambient DCHP air concentrations were reasonably available for the
Agency to review. DCHP in particulates averaged 0.01 ng/m3 in one study (Lee et al.. 2019). Low to
negligible air concentrations are expected from TSCA COUs and air to soil modeling was not
conducted. Thus, EPA qualitatively assessed risk using low exposures via air pathways and a
preliminary indication of no risk.
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Landfill
EPA qualitatively assessed risk of landfill to groundwater and soil DCHP exposure to aquatic and
terrestrial organisms. No hazard data were reasonably available for groundwater-dwelling or soil-
dwelling animals or plants. EPA considered the COC of DCHP to Daphnia (32 |ig/L) to indicate chronic
exposure hazard effects to groundwater dwelling animals. Empirical toxicity data for rats and mice were
used to estimate a hazard threshold value for terrestrial mammals that may ingest soils at 179.3 mg/kg-
bw/day (U.S. EPA. 2024oY
DCHP may be deposited into landfills through various waste streams, including consumer waste,
residential waste, and industrial waste, as well as through municipal waste like dewatered wastewater
biosolids. No studies were identified which reported the concentration of DCHP in landfills or in the
surrounding land. There is limited information regarding DCHP in dewatered biosolids, which may be
sent to landfills for disposal. DCHP is not expected to be persistent in the environment as it is expected
to degrade rapidly under most environmental conditions with delayed biodegradation in low-oxygen
media. DCHP is slightly soluble in water (range from 0.03-1,480 mg/L) and has limited potential to
leach from landfills into nearby groundwater or surface water systems. However, DCHP is expected to
have a high affinity to particulate (log Koc = 4.47) and organic media (log Kow = 4.82), which would
cause significant retardation in groundwater and limit leaching to groundwater. Because of its high
hydrophobicity and high affinity for soil sorption, it is not expected to be bioavailable for uptake. As a
result, the available evidence indicates that migration from landfills to surface water and sediment is
limited, and EPA did not model DCHP leaching from landfills to groundwater or surface water systems.
EPA determined a low likelihood of DCHP persisting in and being bioavailable in groundwater from
landfills for a long enough duration to cause chronic hazard in animals, and thus a preliminary indication
of no risk.
There is limited reasonably available information related to the uptake and bioavailability of DCHP in
soils. DCHPs solubility and sorption coefficients suggest that bioaccumulation and biomagnification
will not be of significant concern for soil-dwelling organisms adjacent to landfills. The combination of
factors such as biodegradation (U.S. EPA. 2024z) and the weight of evidence supporting a lack of
bioaccumulation and lack of biomagnification supports this qualitative assessment that potential DCHP
concentrations in landfills do not present concentrations greater than the hazard thresholds to terrestrial
organisms. EPA determined a low likelihood of DCHP persisting and being bioavailable to solid-
dwelling animals, plants, or in the diets of mammals for a long enough duration to cause chronic hazard,
and thus a preliminary indication of no risk.
Biosolids
EPA qualitatively assessed risk of biosolids to soil DCHP exposure to terrestrial organisms. No hazard
data were reasonably available for soil-dwelling animals or plants. Empirical toxicity data for rats and
mice were used to estimate a hazard threshold value for terrestrial mammals at 179.3 mg/kg-bw/day
(U.S. EPA. 2024o). DCHP may be introduced to biosolids by the absorption or adsorption of DCHP to
particulate or organic material during wastewater treatment. Wastewater treatment is expected to remove
up to 98 percent of DCHP during wastewater treatment via sorption of DCHP to biosolids (Wu et al..
2019). Modeling of DCHP removal in wastewater treatment predicts sorption to account for a total of
71.2 percent removal of DCHP with 70.6 percent overall removal attributed to biosolid sorption and the
remaining 0.6 percent removal attributed to biological treatment (U.S. EPA. 2017). There are currently
no reasonably available U.S.-based studies reporting DCHP concentration in biosolids or in soil
following land application.
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High-end release scenarios were considered not to be applicable to the evaluation of land application of
biosolids. More specifically, high-end releases of DCHP from industrial facilities are unlikely to be
discharged directly to municipal wastewater treatment plants without pre-treatment, and biosolids from
industrial facilities are unlikely to be directly land applied following on-site treatment.
There is limited measured data on concentrations of DCHP in biosolids or soils receiving biosolids and
there is uncertainty that concentrations used in this analysis are representative of all types of
environmental releases. However, the high-quality biodegradation rates and physical and chemical
properties show that DCHP will have limited persistence potential and mobility in soils receiving
biosolids (U.S. EPA. 2024z). The combination of factors such as biodegradation and the weight of
evidence supporting a lack of bioaccumulation and lack of biomagnification supports this qualitative
assessment that potential DCHP concentrations in biosolids do not present concentrations greater than
hazard threshold values to terrestrial organisms. Therefore, EPA determined a low likelihood of DCHP
persisting and being bioavailable to soil-dwelling animals, plants, or in the diets of mammals for a long
enough duration to cause chronic hazard, and thus a preliminary indication of no risk.
Trophic Transfer
EPA did not conduct a quantitative modeling analysis of the trophic transfer of DCHP through food
webs because of the chemical properties and fate of DCHP indicate low potential for bioaccumulation or
biomagnification. Specifically, the Agency does not expect DCHP to persist in surface water,
groundwater, or air. DCHP is not expected to be persistent in the environment as it is expected to
degrade rapidly under most environmental conditions with delayed biodegradation in low-oxygen
media, and DCHP's bioavailability is expected to be limited (U.S. EPA. 2024z). Estimates of the DCHP
limit of water solubility range from 30 to 1,480 |ig/L, leading to uncertainty about DCHP dissolved in
surface water. DCHP is expected to have low bioaccumulation potential, biomagnification potential, and
low potential for uptake based on a log BCF of 2.85 and a log BAF of 1.83 (U.S. EPA. 2024p. z). For
example, a worst-case scenario screening that uses the upper bound of water solubility as the water
concentration (1,480 |ig/L DCHP) and BAF of 67, results in 99 mg/kg-bw DCHP in fish. A similar
calculation results in 11 mg/kg-bw DCHP in fish if the highest modeled concentration from EPA's
VVM-PSC (164 |ig/L) is used. These values are less than the terrestrial mammal threshold value of
179.3 mg/kg-bw/day over 70 days. These values would only be lower in simulations that incorporate
other release and exposure scenarios in a trophic transfer model. Finally, EPA also did not find
reasonably available data sources that report the aquatic bioconcentration, aquatic bioaccumulation,
aquatic food web magnification, terrestrial biota-sediment accumulation, or terrestrial bioconcentration
of DCHP. Therefore, EPA determined a low likelihood of DCHP transferring through food webs to
reach the terrestrial mammal threshold value of 179.3 mg/kg-bw/day and thus a preliminary indication
of no risk.
Distribution in Commerce
EPA evaluated activities resulting in exposures associated with distribution in commerce (e.g., loading,
unloading) throughout the various life cycle stages and COUs (e.g., manufacturing, processing,
industrial use, commercial use, disposal) rather than a single distribution scenario. The Agency lacks
data to assess risks to the environment from environmental releases and exposures related to distribution
of DCHP in commerce as a single OES. However, most of the releases from this COU/OES are
expected to be captured within the releases of other COU/OES because most of the activities (loading,
unloading) generating releases from distribution of commerce are release points of other COU/OESs.
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5.3.3 Overall Confidence and Remaining Uncertainties Confidence in Environmental
Risk Characterization
The environmental risk characterization of DCHP evaluated confidence from environmental exposures
and environmental hazards. Exposure confidence is detailed within U.S. EPA (2024p). the TSD Draft
Environmental Media and General Population and Environmental Exposure Assessment for
Dicyclohexyl Phthalate (DCHP), represented by modeled and monitored data. Hazard confidence was
represented by evidence as reported previously in th q Draft Environmental Hazard Assessment for
Dicyclohexyl Phthalate (DCHP) U.S. EPA (2024o).
The overall confidence in the preliminary risk characterization for the aquatic assessment is robust. EPA
has indicated no risk to aquatic organisms under most realistic release, flow, and solubility scenarios
except in a scenario with the most conservative assumptions. The Agency has robust confidence that the
conservative scenario with worst-case assumptions is unlikely for several reasons. First, EPA has
determined DCHP water releases to be low due to its chemical properties and predicted fate (U.S. EPA.
2024z), making modeled exposure predictions greater than COCs unlikely. Also, DCHP is a solid at
room temperature with considerable variation in the estimates of water solubility that ranges from 30
|ig/L to 1,480 |ig/L. Under EPA's release of DCHP to water generic scenarios, the amount of DCHP that
may be released to surface water as a solid and the amount that is dissolved in water critically depends
on the functional or environmentally relevant solubility of DCHP in water bodies. Evidence from the
only available U.S. monitoring study reported the maximum DCHP at 0.014 |ig/L (Keil et al.. 2011).
plus two toxicity studies that reported DCHP leaving solution above 30 |ig/L (Swedish Chemicals
Agency. 2023; Mathieu-Denoncourt et al.. 2016) suggest that EPA's modeled high-end release and low
stream flow scenario resulting 165 |ig/L DCHP is unlikely to occur in aquatic ecosystems. Thus, no
reasonably available evidence reports dissolved water concentrations as high as 165 |ig/L and the weight
of evidence points to a low likelihood of DCHP concentrations reaching 165 |ig/L.
The environmental hazard to aquatic organisms is also not clear because only two peer-reviewed studies
and a handful of reports are reasonably available for EPA to review. These studies have high data
quality evaluation ratings, but corroborating results from additional studies would improve the accuracy
and precision of the Agency's COC for chronic exposure while increasing the confidence for indications
of low likelihood of risk. All but two of these studies did not find acute exposure effects at
concentrations up to 2,000 |ig/L, indicating that short exposure durations pose little risk to aquatic
organisms. Chronic exposure effects on reproductive endpoints were documented for an invertebrate and
a fish at approximately 30 |ig/L DCHP concentrations. All these studies used solvent carriers to keep
DCHP in solution. Taken together, it remains unclear whether high concentrations of DCHP in the water
column occur in ecosystems and whether these exposure concentrations can persist long enough to incur
reproductive effects on aquatic organisms. Thus, the weight of evidence summarized in this document
leads to the preliminary characterization of no risk to aquatic receptors.
The overall confidence in the preliminary risk characterization for the terrestrial assessment is robust.
EPA has robust confidence that DCHP is not likely to present environmental risk through most scenarios
that may expose DCHP to terrestrial organisms. This confidence is due to the relatively low volumes of
release across COUs, the physical and chemical properties of DCHP, and the low number of studies that
document DCHP in the environment. These result in low to negligible exposure concentrations in air,
landfills, biosolids and soils. Trophic transfer of DCHP through food webs is also unlikely due to
DCHP's chemical and fate properties that indicate that it has low potential to bioaccumulate or
biomagnify in food webs. This weight of evidence of low potential for DCHP exposures in terrestrial
ecosystems—coupled with no reasonably available studies of DCHP hazard effects to wildlife and a
relatively high surrogate mammal hazard threshold from laboratory rodent data—indicate exposure
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3828 above the hazard threshold is an unlikely risk to terrestrial organisms. Although the lack of reasonably
3829 available studies on the hazardous effects of DCHP on wildlife does not rule out hazard and subsequent
3830 risk, the weight of evidence summarized in this document leads to the preliminary indication that risk to
3831 terrestrial receptors is not expected.
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6 UNREASONABLE RISK DETERMINATION
TSCA section 6(b)(4) requires EPA to conduct a risk evaluation to determine whether a chemical
substance presents an unreasonable risk of injury to health or the environment, without consideration of
costs or other non-risk factors, including an unreasonable risk to a PESS identified by EPA as relevant to
the risk evaluation, under the TSCA COUs.
EPA is preliminarily determining that DCHP presents an unreasonable risk of injury to human health
under the COUs. The Agency is preliminary determining that DCHP does not present unreasonable risk
of injury to the environment. This draft unreasonable risk determination is based on the information in
previous sections of this draft risk evaluation, the appendices, and the TSDs of this draft risk evaluation
in accordance with TSCA section 6(b). It is also based on (1) the best available science (TSCA section
26(h)); (2) weight of scientific evidence standards (TSCA section 26(i)); and (3) relevant implementing
regulations in 40 CFR part 702, including, to the extent practicable, the amendments to the procedures
for chemical risk evaluations under TSCA finalized in May 2024 (89 FR 37028; May 3, 2024).
If, in the final TSCA risk evaluation for DCHP, EPA determines that DCHP presents an unreasonable
risk of injury to health or the environment under the COUs, the Agency will initiate risk management for
DCHP by applying one or more of the requirements under TSCA section 6(a) to the extent necessary so
that DCHP no longer presents such risk. The risk management requirements will likely focus on the
COUs significantly contributing to the unreasonable risk. However, under TSCA section 6(a), EPA is
not limited to regulating the specific COUs found to significantly contribute to the unreasonable risk and
may select from among a suite of risk management options related to manufacture, processing,
distribution in commerce, commercial use, and disposal to address the unreasonable risk. For instance,
EPA may regulate "upstream" COUs (e.g., processing, distribution in commerce) to address
"downstream" COUs that significantly contribute to unreasonable risk (e.g., use)—even if the upstream
activities are not significantly contributing to the unreasonable risk. The Agency would also consider
whether such risk may be prevented or reduced to a sufficient extent by action taken under another
federal law, such as referral to another agency under TSCA section 9(a) or use of another EPA-
administered authority to protect against such risk pursuant to TSCA section 9(b), as appropriate.
As noted in the EXECUTIVE SUMMARY, DCHP is used primarily as a plasticizer to make flexible
PVC. It is also used to make building and construction materials; automotive care and fuel products; and
other commercial and consumer products including adhesives and sealants, paints and coatings,
electrical and electronic products. Workers may be exposed to DCHP when making these products or
otherwise using DCHP in the workplace. When it is manufactured or used to make products, DCHP can
be released into the water, where because of its properties, most of it will end up in the sediment at the
bottom of lakes and rivers. If it is released into the air, DCHP will attach to dust particles and then be
deposited onto land or into water. Indoors, DCHP has the potential over time to be come out of products
and adhere to dust particles. If it does, people could inhale or ingest dust that contains DCHP. In
addition to DCHP, workers and consumers can be exposed to other phthalates that have the same
toxicological endpoint (i.e., decreased fetal testicular testosterone). EPA has authored a draft cumulative
risk technical support document of DCHP and five other toxicologically similar phthalates (i.e., DEHP,
DBP, DIBP, BBP, and DINP) that are also being evaluated under TSCA. This TSD will allow EPA to
assess the combined risk to health from multiple chemicals with similar effects simultaneously,
recognizing that human exposure to phthalates is widespread and that multiple phthalates can disrupt
development of the male reproductive system. The use of EPA's cumulative risk assessment (CRA) in
the preliminary risk determination is discussed in more detail in Section 6.1.3 as well as the worker
(Section 6.1.4) and consumer (Section 6.1.5) sections.
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The COUs evaluated for DCHP are listed in Table 1-1. EPA is preliminarily determining the following
COUs based on the DCHP individual analysis and the relative potency factor (RPF) analysis,
significantly contribute to the unreasonable risk to workers:
• Manufacturing - domestic manufacturing;
• Processing - incorporation into formulation, mixture, or reaction product - adhesive and sealant
chemicals in adhesive manufacturing;
• Processing - incorporation into formulation, mixture, or reaction product - plasticizer (adhesive
manufacturing; paint and coating manufacturing; and printing ink manufacturing);
• Processing - incorporation into formulation, mixture, or reaction product - stabilizing agent
(adhesive manufacturing; asphalt paving, roofing, and coating materials manufacturing; and
paints and coating manufacturing)
• Industrial use - finishing agent - cellulose film production;
• Industrial use - inks, toner, and colorant products (e.g., screen printing ink);
• Industrial use - Paints and coatings;
• Commercial use - inks, toner, and colorant products (e.g., screen printing ink); and
• Commercial use - paints and coatings.
EPA is preliminarily determining that the following COUs do not significantly contribute to the
unreasonable risk:
• Manufacturing - importing;
• Processing - incorporation into article - plasticizer (plastics product manufacturing and rubber
product manufacturing);
• Processing - repackaging (e.g., laboratory chemicals);
• Processing - recycling;
• Distribution in commerce;
• Industrial use - adhesives and sealants (e.g., computer and electronic product manufacturing;
transportation equipment manufacturing);
• Industrial use - other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard) (e.g., transportation equipment manufacturing);
• Commercial use - adhesives and sealants;
• Commercial use - building/construction materials not covered elsewhere;
• Commercial use - laboratory chemicals;
• Commercial use - other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard);
• Consumer use - adhesives and sealants;
• Consumer use - other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard);
• Consumer use - other consumer articles that contain dicyclohexyl phthalate from: inks, toner,
and colorants; paints and coatings; adhesives and sealants (e.g., paper products, textiles, products
using cellulose film, etc.); and
• Disposal.
Whether EPA makes a determination of unreasonable risk for a particular chemical substance under
TSCA depends upon risk-related factors beyond exceedance of benchmarks, such as the endpoint under
consideration, the reversibility of effect, exposure-related considerations (e.g., duration, magnitude,
frequency of exposure, population exposed), how PESS groups were considered in the assessment, and
the confidence in the information used to inform the hazard and exposure values. For COUs evaluated
quantitatively, EPA also considers how central tendency or high-end risk estimates represented the risk
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related factors, and the Agency based the risk determination on the risk estimates that best represented
the COUs. Additionally, in this draft risk evaluation, EPA describes the strength of the scientific
evidence supporting the human health and environmental assessments as robust, moderate, or slight.
Robust confidence suggests thorough understanding of the scientific evidence and uncertainties, as well
as the supporting weight of scientific evidence, outweighs the uncertainties to the point where it is
unlikely that the uncertainties could have a significant effect on the risk. Moderate confidence suggests
some understanding of the scientific evidence and uncertainties, and the supporting scientific evidence
weighed against the uncertainties is reasonably adequate to characterize the risk. Slight confidence is
assigned when the weight of scientific evidence may not be adequate to characterize the risk, and when
the Agency is making the best scientific assessment possible in the absence of complete information.
This draft risk evaluation discusses important assumptions and key sources of uncertainty in the risk
characterization, and these are described in more detail in the respective weight of scientific evidence
conclusions sections for fate and transport, environmental release, environmental exposures,
environmental hazards, and human health hazards, respectively. It also includes overall confidence and
remaining uncertainties sections for human health and environmental risk characterizations.
Additionally, EPA considered, where relevant, the Agency's analyses on aggregate exposures and
cumulative risk. Aggregate exposure analyses consider effects on populations that are exposed to DCHP
via multiple routes (e.g., dermal contact, ingestion, and inhalation). Cumulative risk refers to human
health risks related to exposures to multiple chemicals—in this case the six phthalates considered in the
CRA TSD. EPA has applied the methods and principles of CRA outlined in EPA's Draft Proposed
Approach for Cumulative Risk Assessment (CRA) of High-Priority Phthalates and a Manufacturer-
Requested Phthalate under the Toxic Substances Control Act (U.S. EPA. 2023 c) and EPA's Draft
Technical Support Document for the Cumulative Risk Analysis of Di(2-ethylhexyl) Phthalate (DEHP),
Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl Phthalate (DIBP), Dicyclohexyl
Phthalate (DCHP), and Diisononyl Phthalate (DINP) Under the Toxic Substances Control Act (TSCA)
(U.S. EPA. 2024ah). to derive non-cancer risk estimates for occupational and consumer exposures.
These cumulative, non-cancer risk estimates are considered in addition to the individual risk estimates
for DCHP. Notably, other authoritative and regulatory agencies (i.e., CPSC, Health Canada, ECHA,
NICNAS, EFSA) have evaluated phthalates, including DCHP, for cumulative risk. Further, independent,
expert peer reviewers on the SACC endorsed EPA's proposal to conduct a CRA of phthalates under
TSCA because it represents the best available science. The Agency's approach for assessing cumulative
risk, which is described in detail in the draft CRA TSD (U.S. EPA. 2024ah). incorporates feedback from
the SACC (U.S. EPA. 2023f) who peer reviewed EPA's draft proposed approach in May 2023 (U.S.
EPA. 2023f).
6.1 Human Health
Calculated non-cancer risk estimates (MOEs) can provide a risk profile of DCHP by presenting a range
of estimates for different health effects for different COUs. When characterizing the risk to human
health from occupational exposures during risk evaluation under TSCA, EPA conducts baseline
assessments of risk and makes its determination of unreasonable risk from a baseline scenario that does
not assume use of respiratory protection or other personal protective equipment (PPE).5 A calculated
MOE that is less than the benchmark MOE is a starting point for informing a determination of
5 It should be noted that, in some cases, baseline conditions may reflect certain mitigation measures, such as engineering
controls, in instances where exposure estimates are based on monitoring data at facilities that have engineering controls in
place.
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unreasonable risk of injury to health, based on non-cancer effects. It is important to emphasize that these
calculated risk estimates alone are not bright-line indicators of unreasonable risk.
6.1.1 Populations and Exposures EPA Assessed for Human Health
EPA has evaluated risk to adolescent and adult workers (including ONUs and female workers of
reproductive age) 16 years of age and older; consumer users and bystanders, including infants and
children; and the general population, including infants and children and people who consume fish. The
Agency evaluated these risks using reasonably available monitoring and modeling data for inhalation
and dermal exposures, as applicable. EPA has evaluated risk from inhalation and dermal exposure of
DCHP to workers, including ONUs, as appropriate for each exposure scenario, but the primary route of
exposure was inhalation. The Agency evaluated risk from inhalation, dermal, and oral-exposure to
consumer users and inhalation exposures to bystanders. Finally, EPA also evaluated risk from exposures
from surface water, drinking water, fish ingestion, ambient air, and land pathways (i.e., landfills and
application of biosolids) to the general population.
Descriptions of the data used for human health exposure and human health hazards are provided in
Sections 4.1 and 4.2, respectively, in this draft risk evaluation. Uncertainties for overall exposures and
hazards are presented in this draft risk evaluation, the Draft Consumer and Indoor Dust Exposure
Assessment for Dicyclohexyl phthalate (DCHP) (U.S. EPA. 2024c). the Draft Environmental Media and
General Population and Environmental Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S.
EPA. 2024p). the Draft Environmental Release and Occupational Exposure Assessment for
Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024q). and the Draft Non-Cancer Human Health Hazard
Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024v) and are considered in this
preliminary unreasonable risk determination.
6.1.2 Summary of Human Health Effects
EPA is preliminarily determining that the unreasonable risk presented by DCHP is due to
• non-cancer effects in workers from inhalation exposures;
• non-cancer effects in workers from aggregate exposures (i.e., inhalation + dermal); and
• non-cancer effects in workers from cumulative exposures (i.e., DCHP + other phthalates).
With respect to health endpoints upon which EPA is basing this preliminary unreasonable risk
determination, the Agency has robust overall confidence in the proposed POD based on the developing
male reproductive system for use in characterizing risk from exposure to DCHP for acute, intermediate,
and chronic exposure scenarios. In addition, overall, EPA has robust confidence in the draft factors used
in the RPF analysis and cumulative risk analysis. See Section 4.4 and EPA's Draft Technical Support
Document for the Cumulative Risk Analysis of Di(2-ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate
(DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl Phthalate (DIBP'), Dicyclohexyl Phthalate (DCHP),
and Diisononyl Phthalate (DINP) Under the Toxic Substances Control Act (TSCA) (U.S. EPA. 2024ah).
for further description of the RPF analysis.
DCHP has not been evaluated for carcinogenicity in any two-year cancer bioassays. EPA therefore
evaluated the relevance of read-across approaches to assess potential cancer hazards of DCHP based on
cancer bioassays and MOA information available for other phthalates being evaluated under TSCA (i.e.,
DEHP, DBP, BBP, DINP, DIDP) as discussed in the Draft Cancer Human Health Hazard Assessment
for Di(2-ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP),
Diisobutyl Phthalate (DIBP), and Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2025a). Overall, based
on the weight of scientific evidence, EPA preliminarily concludes that potential carcinogenicity of
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DCHP is not a significant remaining source of uncertainty in the quantitative and qualitative risk
characterization, despite the lack of DCHP carcinogenicity bioassays.
EPA's exposure and overall risk characterization PODs and MOEs are summarized in Section 4.3, with
specific health risk estimates for workers (including ONUs), consumers, bystanders, and the general
population presented in Section 4.3.2 (workers), Section 4.3.3 (consumers and bystanders), Section 4.3.4
(general population), and Section 4.3.5 (PESS). Again, these MOEs and benchmarks are not bright-
lines, and EPA has discretion to consider other risk-related factors when determining if a COU
significantly contributes to the unreasonable risk determination of the chemical substance.
6.1.3 Basis for Unreasonable Risk to Human Health
In developing the exposure and hazard assessments for DCHP, EPA analyzed reasonably available
information to ascertain whether some human populations may have greater exposure and/or
susceptibility than the general population to the hazard posed by DCHP. For this DCHP draft risk
evaluation, EPA has accounted for the following PESS groups: people who are expected to have greater
exposure to DCHP, such as people exposed to DCHP at work; women of reproductive age; infants and
children who frequently have contact with consumer products and/or articles containing high
concentrations of DCHP; those who may have greater intake of DCHP per body weight (e.g., infants,
children, adolescents); those exposed to DCHP through certain age-specific behaviors (e.g., mouthing by
infants and children); and Tribes and subsistence fishers whose diets include large amounts of fish.
Additionally, EPA identified population group lifestages that may have greater susceptibility to the
health effects of DCHP as PESS, including women of reproductive age, pregnant women, infants,
children, and adolescents. A full PESS analysis is provided in Section 4.3.5 of this draft risk evaluation.
Risk estimates based on high-end exposure levels (e.g., 95th percentile, or high intensity scenarios) are
generally intended to cover individuals with sentinel exposures, whereas risk estimates at the central
tendency exposure are generally estimates of average or typical exposures. For DCHP, EPA was able to
calculate risk estimates for PESS groups in this assessment (e.g., female workers of reproductive age,
infants and children). In addition, the non-cancer PODs are based on susceptible populations. The
POD—which is used for acute, intermediate, and chronic exposure durations—is based on effects
observed during pregnancy whereas the intermediate and chronic PODs are based on reproductive
effects observed in adolescent males. The use of either central tendency or high-end risk estimates for
female workers of reproductive age to make a determination of unreasonable risk was based on
assumptions about the COU using reasonably available information about a typical scenario and process
within the COU. In determining whether a COU significantly contributes to the unreasonable risk to
DCHP, EPA considered the central tendency for most of the occupational estimates. Central tendency
values of exposure are often expected to be the most reflective of worker exposures within the DCHP
COUs, as explained further in Section 6.1.3.
To make an unreasonable risk determination for consumers, EPA considered risk estimates for
consumers (e.g., infants and children) representing high-intensity exposure levels, which are distinct
from the occupational central-tendency or high-end risk estimates that represent a point within the
modeled distribution. For example, high-intensity consumer indoor dust exposure scenarios assumed
that people are in their homes for longer periods than the medium- or lower- intensity scenarios. Health
parameters were also adjusted for each population, such as inhalation rates used per lifestage.
EPA has also aggregated exposures across certain routes for workers, including ONUs, and consumers
for COUs with quantitative risk estimates. For most occupational COUs, aggregation of inhalation and
dermal exposures led to negligible differences in risk estimates when compared with risk estimates from
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inhalation alone, because inhalation is the predominant route of exposure. For consumers, dermal, oral,
and inhalation routes were aggregated, which did not result in any risk estimates below the benchmark
MOE, similar to the consumer risks from individual exposure routes. The UF of 10 for human variability
that EPA applied to MOEs accounts for increased susceptibility of populations such as children and
elderly populations. Detailed information on how EPA characterized sentinel and aggregate risks is
provided in Section 4.1.5.
In addition to the analysis done for DCHP alone (referred to as "individual analysis"), EPA applied both
the methods and principles of CRA {Draft Proposed Approach for Cumulative Risk Assessment (CRA)
ofHigh-Priority Phthalates and a Manufacturer-Requested Phthalate under the Toxic Substances
Control Act (U.S. EPA. 2023 c). as well as the Draft Technical Support Document for the Cumulative
Risk Analysis of Di(2-ethyIhexy 1) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate
(BBP), Diisobutyl Phthalate (DIBP), Dicyclohexyl Phthalate (DCHP), andDiisononyl Phthalate
(DINP) Under the Toxic Substances Control Act (TSCA) (U.S. EPA. 2024ah)). to derive non-cancer risk
estimates for occupational and consumer exposures. EPA's draft CRA includes cumulative exposure to
other toxicologically similar phthalates being evaluated under TSCA (i.e., DEHP, DBP, BBP, DIBP, and
DINP) and uses an "RPF analysis" to characterize risk. Using a meta-analysis and BMD modeling
approach to model decreased fetal testicular testosterone, EPA derived an RPF for DCHP of 1.66 based
on BMD40. This means DCHP exposures, when multiplied by the relative potency factor and expressed
in terms of index chemical (i.e., DBP) equivalents, increased by 66 percent.
The above approach accounts for potency differences among chemicals in a mixture and scales the dose
of one chemical to an equitoxic dose of another chemical (i.e., the index chemical). The chemical
selected as the index chemical (i.e., DBP) is the best characterized toxicologically and considered to be
representative of the type of toxicity elicited by other components of the mixture, which allows EPA to
utilize more fetal testicular testosterone data in the low-end range of the dose-response curve to gain a
better understanding of the hazards of DCHP at the low-end range of the dose-response curve.
Additionally, the index chemical (i.e., DBP) POD is 12.5 percent lower (i.e., more sensitive) than the
individual DCHP POD, which also contributes to the lower RPF analysis MOEs as compared with the
individual non-scaled DCHP risk estimates. Non-cancer risk associated with exposure to an individual
phthalate or a mixture can then be assessed by calculating an MOE, which is then compared with the
benchmark MOE. EPA has robust confidence in the proposed POD for the index chemical (i.e., DBP)
and the EPA-derived RPF for DCHP used to calculate the RPF analysis and cumulative MOEs.
The draft CRA TSD also includes the addition of a non-attributable cumulative exposure to DEHP,
DBP, BBP, DIBP, and DINP as estimated from NHANES urinary biomonitoring data using reverse
dosimetry. The NHANES exposure is non-attributable—meaning it cannot be attributed to specific
COUs or other sources, but likely includes exposures attributable to both TSCA COUs and other sources
(e.g., diet, food packaging cosmetics). However, as discussed in more detail below, DCHP's toxicity
reflected in the previously discussed 66 percent increase in exposure expressed in terms of index
chemical equivalents is the primary factor leading to lower RPF analysis MOEs and indications of
unreasonable risk. Adding in the non-attributable cumulative exposure to other phthalates contributes
approximately 7.1 percent to the risk cup for female workers of reproductive age, assuming a benchmark
MOE of 30 (see Section 4.4.4 for the cumulative worker risk estimates). EPA has robust confidence in
the estimates of non-attributable cumulative exposure derived from NHANES urinary biomonitoring
data using reverse dosimetry. Note that this draft risk evaluation has been released for public comment
and will undergo independent, expert scientific peer review by the SACC. EPA will issue a final DCHP
risk evaluation after considering input from the public and peer reviewers, which will include peer
review of EPA's draft RPF analysis.
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6.1.4 Workers
EPA took into consideration both the individual analysis and the draft RPF analysis; based on the
occupational and cumulative risk estimates and related risk factors from the individual and draft RPF
analyses, the Agency is preliminarily determining that the non-cancer effects from worker inhalation
exposure to DCHP and worker aggregate exposures to DCHP from manufacturing and eight processing,
industrial, and commercial COUs significantly contribute to the unreasonable risk.
Nearly all occupational COUs were quantitatively assessed in the individual analysis. EPA analyzed
vapor/mist and/or particulate concentration inhalation exposure in the occupational scenarios, and
separate estimates of central tendency and high-end exposures were made for adolescent and adult (16+
years) workers, female workers of reproductive age, and ONUs. Dermal exposure in the OESs in the
individual analysis was analyzed using the acute potential dose rate. For the COUs assessed, dermal
exposure for ONUs was evaluated using the central tendency estimates for workers because the risk to
ONUs are assumed to be equal to or less than risk to workers who handle materials containing DCHP as
a part of their job. Risk was not indicated to workers, including ONUs, for any COU at the high-end or
central tendency for dermal exposure estimates. More information on occupational risk estimates is in
Section 4.3.2 of this risk evaluation.
Within the individual analysis, non-cancer risk estimates were calculated from acute, intermediate, and
chronic inhalation and dermal exposures. However, the draft RPF analysis focused on non-cancer risk
estimates from acute exposure as there is evidence that effects on the developing male reproductive
system can result from a single exposure during the critical window of development. Additionally,
because relative potency factors are based on reduced fetal testicular testosterone, EPA considers the
most directly applicable populations for the draft RPF analysis to be pregnant women, women of
reproductive age, and male infants and male children. More information on the draft RPF analysis is
provided in Section 4.4 of this risk evaluation.
In the absence of inhalation monitoring data, EPA used inhalation exposure models to estimate central
tendency and high-end worker (including ONU) inhalation exposures using the Particulates Not
Otherwise Regulated (PNOR) Model. In the individual analysis, there were multiple COUs where the
exposure and risk estimates are based on the assumption that the concentration of DCHP in workplace
dust is the same as the maximum concentration of DCHP manufactured or in the product. It is likely that
workplace dusts contain a variety of constituents besides the final product, so the concentration of
DCHP in workplace dust is likely less than the concentration of DCHP in the final product. Therefore, in
those cases, central tendency values of exposure are expected to be the most reflective of worker
exposures within the DCHP COUs, and EPA is relying on central tendency when considering estimates
from the PNOR model (i.e., dust) in this preliminary unreasonable risk determination.
There are notable differences in the risk estimates from the individual analysis and the RPF analysis for
four OESs represented by four COUs: Domestic manufacturing; Processing - incorporation into
formulation, mixture, or reaction product - adhesive and sealant chemicals in (adhesive manufacturing);
Processing - incorporation into formulation, mixture, or reaction product - plasticizer in (adhesive
manufacturing, paint and coating manufacturing, and printing ink manufacturing); and Processing -
incorporation into formulation, mixture, or reaction product - stabilizing agent in (adhesive
manufacturing, paint and coating manufacturing, and asphalt paving, roofing and coating materials
manufacturing). All four COUs have the same risk estimates. At the central tendency in the individual
analysis, these COUs have acute inhalation and acute aggregate risk estimates for female workers of
reproductive age that initially do not appear to significantly contribute to unreasonable risk because they
are slightly above the benchmark of 30 (i.e., MOEs of 36 for acute inhalation and 35 for acute aggregate
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exposure). However, at the central tendency using the draft RPF analysis, those same four COUs have
acute inhalation and acute aggregate risk estimates for DCHP exposure expressed in index chemical
equivalents that are well below the benchmark for female workers of reproductive age (i.e., MOEs of
19.1 for acute inhalation and 18.5 for aggregate exposure). Adding in the non-attributable cumulative
phthalate exposure (i.e., NHANES) to the aggregate exposure lowers the MOE only slightly from 18.5
to 17.7. A COU example of the risk estimates is presented in Table 6-1.
Table 6-1. Example of Occupational Risk Estimates for OES Manufacturing (Female Workers of
Reproductive Age and I
lenchmark MOE = 3
0)
Life Cycle
Stage/
Category
Subcategory
OES
Exposure
Level
Individual Analysis
RPF Analysis
Acute
Inhalation
Risk
Estimates
Acute
Aggregate
Risk
Estimates
Acute
Inhalation
Risk
Estimates
Acute
Aggregate
Risk
Estimates
Cumulative
(Acute Aggregate
+ Cumulative
Non-
attributable)
Manufacturing
- Domestic
manufacturing
Domestic
manufacturing
Manufacturing
High-End
3.5
3.5
1.8
1.8
1.8
Central
Tendency
36
35
19.1
18.5
17.7
Note that for DCHP, as explained in Section 6.1.3, most of the difference between the MOEs calculated
using the individual analysis and the MOEs calculated using the draft RPF analysis is due to scaling
DCHP to the index chemical and not to the additional, non-attributable cumulative risk from NHANES.
As previously noted, the phthalate selected as the index chemical (i.e., DBP) is the best characterized
toxicologically and considered to be representative of the type of toxicity elicited by other components
of the mixture. This allows EPA to utilize more fetal testicular testosterone data in the low-end range of
the dose-response curve to gain a better understanding of the hazards of DCHP at the low-end range of
the dose-response curve. This analysis provides a more robust basis for assessing the dose-response for
the common hazard endpoint (i.e., reduced fetal testicular testosterone) across the six toxicologically
similar phthalates included in the CRA, including DCHP.
Additionally, there are two COUs associated with PVC plastics compounding, PVC plastics converting,
non-PVC material compounding, and non-PVC material converting (i.e., Processing - incorporation into
formulation, mixture, or reaction product - plasticizer and Processing - incorporation into formulation,
mixture, or reaction product - stabilizing agent) that do not indicate risk in either the individual or the
RPF analysis. These OESs have acute inhalation and acute aggregate risk estimates for female workers
of reproductive age above the benchmark MOE of 30 in the individual analysis (i.e., MOEs range from
76-378 for acute inhalation and 71-285 for acute aggregate exposure) and for risk estimates based on
the RPF analysis (i.e., MOEs range from 40-199 for acute inhalation and 37-150 for acute aggregate
DCHP exposure expressed in index chemical equivalents). The acute aggregate MOEs in the RPF
analysis range from 34 to 110 when including non-attributable cumulative risk from NHANES.
As a result, EPA is preliminarily determining that those four COUs, with the exception of the activities
associated with plastic and rubber manufacturing discussed in the previous paragraph, significantly
contribute to the unreasonable risk to human health. This determination is based on the central tendency
acute inhalation and aggregate (i.e., inhalation plus dermal) exposure estimates for female workers of
reproductive age from the individual analysis, and it takes into consideration the RPF analysis acute
inhalation, aggregate and non-attributable cumulative (from NHANES) risk estimates. It is also
important to note that while EPA is relying on the central tendency, as it is expected to be the most
reflective of worker exposures, the high-end risk estimates for acute inhalation and aggregate risk
estimates for female workers of reproductive age for these four COUs are also well below the MOE
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benchmark of 30 (i.e., MOEs of 3.5 for acute inhalation and 3.5 for acute aggregate exposure in the
individual analysis).
• Manufacturing - domestic manufacturing;
• Processing - incorporation into formulation, mixture, or reaction product - adhesive and sealant
chemicals in adhesive manufacturing;
• Processing - incorporation into formulation, mixture, or reaction product - plasticizer in
adhesive manufacturing; paint and coating manufacturing; and printing ink manufacturing; and
• Processing - incorporation into formulation, mixture, or reaction product - stabilizing agent in
adhesive manufacturing; asphalt paving, roofing, and coating materials manufacturing; and
paints and coating manufacturing.
At the central tendency in the individual analysis, there are five other COUs (represented by two OESs
that were assessed as paints and coatings both as liquids and solids) that have acute inhalation and
aggregate risk estimates for female workers of reproductive age that are above the benchmark MOE of
30 (i.e., MOEs of 41 for acute inhalation and 40 for aggregate exposure for liquids/spray application and
MOEs of 62 for acute inhalation and 59 for aggregate exposure for solids) and risk estimates that are
below the benchmark at the high-end estimates (i.e., MOEs of 2 for acute inhalation and 2 for aggregate
exposure for liquids/spray application and MOEs of 3.5 for acute inhalation and 3.5 for aggregate
exposure for solids). As explained above, the central tendency values of exposure are expected to be the
most reflective of worker exposures within the DCHP COUs when utilizing the PNOR model, such as
for applications of paints and coatings solids—because the high-end assumption about the concentration
of DCHP in workplace dust is extremely conservative and highly unlikely in actual workplaces. For
paints and coatings liquids, in general, central tendency represents the typical exposure of most workers
to DCHP through spray application; however, a confluence of a subset of variables (e.g., low ventilation,
high-pressure spray, etc.) would result in risk below the benchmark (of which EPA assessed a DCHP
product that resulted in such an example). While most workers are not expected to experience elevated
exposures (i.e., greater than 90th percentile of mist concentration data for an 8-hour period) on a daily
basis, it is considered plausible and expected for such exposures to occur in an acute 1-day scenario.
Therefore, for these COUs, EPA's preliminary risk determination is based on the estimates associated
with the high-end scenario. This is consistent with EPA's approach to liquid spray applications in other
phthalate risk evaluations.
Additionally, at the high-end in the draft RPF analysis, those same five COUs, which are listed below,
have acute inhalation and aggregate risk estimates that are well below the benchmark for female workers
of reproductive age for liquids (i.e., MOEs of 1 for acute inhalation and 1 for aggregate exposure for
liquid application for high end). Adding in the non-attributable cumulative phthalate exposure (i.e.,
NHANES) to the aggregate exposure does not impact the high-end estimates at all. A COU example of
the risk estimates for both liquids and solids is represented in
Table 6-2; all five COUs (Industrial use of a finishing agent in cellulose film production, Industrial and
commercial use of paints and coatings, and Industrial and commercial use of inks, toner, and colorant
products [e.g., screen printing ink]) have the same risk estimates for each scenario of liquids vs. solids.
Because risk estimates for liquids in the individual analysis, as well as the draft RPF analysis, are well
below the benchmark MOE, EPA is preliminarily determining that those five COUs significantly
contribute to the unreasonable risk of injury to human health based on the high-end acute inhalation and
aggregate exposure estimates for female workers of reproductive age. The Agency also considered the
RPF analysis acute inhalation, aggregate, and non-attributable cumulative (from NHANES) risk
estimates.
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• Industrial use - finishing agent - cellulose film production;
• Industrial use - inks, toner, and colorant products (e.g., screen printing ink);
• Industrial use - paints and coatings;
• Commercial use - inks, toner, and colorant products (e.g., screen printing ink); and
• Commercial use - paints and coatings.
Table 6-2. Example of Occupational Risk Estimates for OES Applications of Paints and Coatings
Female Workers of B
reproductive Age and Benchmark MOE = 30)
Life Cycle
Stage/
Category
Subcategory
OES
Exposure
Level
Individual Analysis
RPF Analysis
Acute
Inhalation
Risk
Estimates
Acute
Aggregate
Risk
Estimates
Acute
Inhalation
Risk
Estimates
Acute
Aggregate
Risk
Estimates
Cumulative (Acute
Aggregate +
Cumulative Non-
attributable)
Industrial
Use -
Finishing
agent
Cellulose film
production
Application
of paints and
coatings -
liquids
High-End
2.0
2.0
1.0
1.0
1.0
Central
Tendency
41
40
21.7
21.0
19.9
Industrial
Use -
Finishing
agent
Cellulose film
production
Application
of paints and
coatings -
solids
High-End
3.5
3.5
1.9
1.9
1.8
Central
Tendency
62
59
32.7
31.1
28.9
One COU, Distribution in commerce, did not have quantitative risk estimates for workers. For the
purposes of the unreasonable risk determination and the individual analysis, distribution in commerce of
DCHP includes transporting DCHP or DCHP-containing products between work sites or to final use
sites, as well as loading and unloading from transport vehicles. Individuals in occupations that transport
DCHP-containing products (e.g., truck drivers) or workers who load and unload transport trucks may
encounter DCHP or DCHP-containing products. EPA did not calculate risk estimates for the specific
Distribution in commerce COU. The Agency evaluated activities resulting in exposures associated with
distribution in commerce (e.g., loading, unloading) throughout the various life cycle stages and COUs
(e.g., manufacturing, processing, industrial use, commercial use, disposal) rather than a single
distribution scenario. Although some worker activities associated with distribution in commerce are
similar to COUs such as manufacturing or import, it is expected that workers involved in distribution in
commerce spend less time exposed to DCHP than workers in manufacturing or import facilities because
only part of the workday is spent in an area with potential exposure. Therefore, occupational exposures
associated with the distribution in commerce COU are expected to be less than other COUs with similar
worker activities and the Agency preliminarily determines that distribution in commerce does not
significantly contribute to DCHP's unreasonable risk to human health.
In the overall occupational assessment for the individual analysis, EPA has moderate confidence in the
assessed occupational inhalation and dermal exposure scenarios (Table 4-5) and robust confidence in the
non-cancer POD selected to characterize risk from acute, intermediate, and chronic duration exposures
to DCHP. The Agency has moderate confidence in the risk estimates calculated for worker and ONU
inhalation and dermal exposure scenarios. More information on EPA's confidence in these risk estimates
and the uncertainties associated with them can be found in Section 4.3.2.
For the draft RPF analysis, EPA has robust confidence in the relative potency factors and index
chemical POD used to calculate the MOEs. To derive RPFs and the index chemical POD, EPA
integrated data from multiple studies evaluating fetal testicular testosterone using a meta-analysis
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approach and conducted BMD modeling. This meta-analysis and BMD modeling approach represents a
refinement of the NOAEL/LOAEL approach used in the individual DCHP assessment and therefore
increases EPA's confidence in the risk estimates (for further information, see Section 4.4). Finally, EPA
has robust confidence in the non-attributable cumulative exposure estimates for DEHP, DBP, BBP,
DIBP, and DINP derived from NHANES urinary biomonitoring data using reverse dosimetry. Given the
fast elimination kinetics of phthalates, NHANES biomonitoring data is not expected to capture low-
frequency, high-intensity exposures and therefore is not intended to be an estimate of acute cumulative
phthalate exposure. Overall, EPA has moderate confidence in the dermal and inhalation exposure
assessments for all nine of the COUs showing risk at the central tendency in the RPF analysis.
6.1.5 Consumers
Based on the consumer risk estimates and related risk factors, EPA's preliminarily determination is that
consumer uses do not significantly contribute to the unreasonable risk of DCHP. The consumer and
bystander exposure scenarios described in this draft risk evaluation represent a wide selection of
consumer use patterns. EPA did not find MOEs that were below the benchmark for any consumer COU.
For DCHP, EPA assessed consumer risk from inhalation, ingestion, and dermal exposures, as well as
aggregated exposure across consumer COUs. Consumer and bystander populations assessed were infant
(<1 year), toddler (1-2 years), preschooler (3-5 years), middle childhood (6-10 years), young teen (11-
15 years), teenager (16-20), and adult (21+ years). A screening-level assessment for consumers was
conducted considering high-intensity exposure scenario risk estimates, which relies on conservative
assumptions to assess exposures that would be expected to be on the high-end of the expected exposure
distribution. All high-end MOEs were above the benchmark MOE for all consumer COUs. MOEs for
high-intensity exposure scenarios ranged from 56 to 17,000,000. In addition, the highest levels (acute
durations) were calculated using the more sensitive and robust relative potency factor analysis described
in Section 4.4.5 and added to estimates of national non-attributable cumulative exposure of five
toxicologically similar phthalates (i.e., DEHP, DBP, BBP, DIBP, and DINP) so that an estimate of
cumulative risk could be considered. The cumulative risk estimates, listed in Table 4-23, also did not
indicate risk to consumers and all MOEs were well above the benchmark for all COUs.
EPA has moderate and robust confidence in the assessed inhalation, ingestion, and dermal consumer
exposure scenarios, and robust confidence in the acute, intermediate, and chronic non-cancer PODs
selected to characterize risk from acute, intermediate, and chronic duration exposures to DCHP. No
intermediate duration was assessed for any consumer use outside of automobile adhesives. The exposure
doses used to estimate risk relied on conservative, health-protective inputs and parameters that are
considered representative of a wide selection of use patterns. In addition, EPA has robust confidence in
the RPFs and index chemical POD used to calculate the RPF analysis and cumulative MOEs as well as
in the derived estimates of non-attributable cumulative exposure from NHANES urinary biomonitoring
using reverse dosimetry. More information on the Agency's confidence in these risk estimates and the
uncertainties associated with them can be found in this draft risk evaluation and the Draft Consumer and
Indoor Dust Exposure Assessment DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024c).
6.1.6 General Population
EPA employed a screening-level approach for general population exposures for DCHP because of
limited environmental monitoring data for DCHP and lack of location data for DCHP releases. If risks
were not indicated for an individual (adult, infant, etc.) identified as having the potential for the highest
exposure associated with a COU for a given pathway of exposure (i.e., at high-end or the 95th
percentile), then that pathway was determined not to significantly contribute to the risk and was not
further analyzed. Also, as a part of EPA's screening-level approach, the Agency considered the
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environmental concentration of DCHP in a given environmental medium resulting from the OES (e.g.,
PVC plastics compounding) that had the highest release compared with any other OES for the same
releasing media. Release estimates from OESs resulting in lower environmental media concentrations
were not considered for this screening-level assessment. For DCHP, EPA did not evaluate cumulative
risk for the general population from environmental releases because after using the previously described
conservative screening-level approach, the Agency did not identify any pathways of concern, indicating
that refinement and further evaluation were not necessary. EPA evaluated surface water, sediment,
drinking water, fish ingestion, and ambient air pathways quantitatively, and land pathways (i.e., landfills
and application of biosolids) qualitatively (see Section 4.1.3).
EPA is preliminarily determining that the COUs do not significantly contribute to the unreasonable risk
of DCHP to the general population from the ambient air—including people living or working near
facilities (fenceline populations)—based on analysis of non-cancer risk. Although EPA is preliminarily
determining that nine COUs significantly contribute to unreasonable risk of DCHP due to occupational
exposures (e.g., through dust that a worker may experience in the chemicals industry; see also Section
6.1.4), the general population exposures from DCHP COUs, including those, are minimal and do not
indicate unreasonable risk. This is due in part to the physical and chemical properties of DCHP; for
example, it has low bioaccumulation potential, low water solubility (1.48 mg/L), low affinity for
sorption to soil, and is unlikely to migrate. EPA's preliminary determination for each pathway (e.g.,
land, surface water, fish ingestion) is discussed below in more detail.
Land Pathway
Due to DCHP's low water solubility (1.48 mg/L) and low persistence under most conditions, DCHP is
unlikely to migrate from land-applied biosolids to groundwater via runoff and is unlikely to be present in
landfill leachate or be mobile in soils. For these reasons, biosolids and landfill were evaluated
qualitatively. As such, EPA does not expect general population exposure to DCHP to occur via the land
pathway. Therefore, the Agency is preliminarily determining that the land pathway does not
significantly contribute to the unreasonable risk for DCHP. For further information, see Section 4.3.4.
Drinking Water and Incidental Surface Water Ingestion and Dermal Contact
EPA used the highest possible DCHP concentration in surface water due to facility release (i.e., in the
immediate water body receiving the effluent) to quantitatively evaluate the risk to the general population
from exposure to DCHP from drinking water or incidental ingestion and dermal contact during
recreational swimming. The Agency took the high-end exposure estimates associated with the COU with
the highest total water column concentration to calculate an MOE. Releases associated with the PVC
plastics compounding OES (i.e., plasticizer in plastic material and resin manufacturing and plastics
product manufacturing and stabilizing agent in plastics product manufacturing) resulted in the highest
total water column concentrations, with the lowest 30-day average flow that occurs once every 5 years
(i.e., 30Q5 water concentration) of 126 |ig/L without wastewater treatment and 39.6 |ig/L when run
under an assumption of 68.6 percent wastewater treatment removal efficiency. These water column
concentrations were used to estimate dermal exposure and incidental ingestion of DCHP while
swimming for adults (21+ years), youths (11-15 years), and children (6-10 years). MOEs for general
population exposure through incidental ingestion and dermal contact during swimming were well above
the benchmark MOE of 30 and ranged from 2,171 to 6,310 for scenarios assuming no wastewater
treatment and from 5,521 to 20,000 for scenarios assuming 68.6 percent wastewater treatment removal
efficiency (Table 4-16).
Based on this screening level assessment, risk for non-cancer health effects is not expected for the
surface water pathway. For the drinking water pathway, modeled surface water concentrations were
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used to estimate drinking water exposures. Drinking water exposure to DCHP was calculated for various
age groups—but even at the most susceptible lifestage, infants (birth to <1 year), risk is not expected.
Acute MOEs through drinking water ingestion were 135 and 430 without and with wastewater
treatment, respectively, for the lifestage (i.e., infants) with the highest exposure (Table 4-16). Therefore,
the drinking water pathway is not considered to be a pathway of concern for DCHP exposure for the
general population and EPA is preliminarily determining that the drinking water and surface water
pathway do not significantly contribute to the unreasonable risk for DCHP for the general population.
For further information, see Section 4.3.4.
Fish Ingestion
EPA evaluated potential risk from exposure to DCHP through fish ingestion using a screening4evel
analysis based on conservative exposure estimates for adults in the general population, adult subsistence
fishers, and adult Tribal populations. The Agency started with the water solubility limit as an upper limit
of DCHP concentration in surface water and determined refinements were needed because the
screening-level risk estimates were below the benchmark MOE of 30. Refinements using modeled
concentrations at the 50th percentile (or P50 flow rate) were needed for the adult subsistence fisher and
adult Tribal populations because the water solubility limit resulted in risk estimates below the
benchmark. Because the P50 modeled concentrations still resulted in risk estimates below benchmarks
for Tribal populations, EPA further refined its analysis by incorporating higher flow rates and treatment
efficiency. Hydrologic flow data were categorized into median flow (P50), 75th percentile flow (P75),
and 90th percentile flow (P90). The Agency expects high-end releases to discharge to surface waters
with higher flow conditions (e.g., P75 and P90). Exposure estimates based on the P50 flow rate resulted
in risk estimates below the benchmark. Risk estimates for fish ingestion generated at concentrations of
DCHP at the water solubility limit or at highest measured concentrations in surface water did not
indicate risk to Tribal populations. MOEs based on conservative values, such as surface water
concentration from a stormwater catchment area, still resulted in risk estimates that are above their
benchmarks. Therefore, EPA is preliminarily determining that fish ingestion does not significantly
contribute to the unreasonable risk for DCHP for Tribal members, subsistence fishers, and the general
population. For further information, see Section 4.3.4.
Inhalation
EPA estimated ambient air concentrations using results from dispersion scenarios. The highest modeled
95th percentile annual ambient air concentration across all release scenarios was 67.57 |ig/m3 at 100 m
from the releasing facility for the Application of paints and coatings OES. This OES was the only one
assessed for the purpose of a screening-level assessment as it was associated with the highest ambient air
concentration. MOEs for general population exposure through inhalation were both well above the
benchmark MOE of 30 (i.e., 192 for acute and 281 for chronic; see also Table 4-18). Therefore, based
on this screening-level analysis, risk for non-cancer health effects is not expected for the ambient air
pathway and EPA is preliminarily determining that the ambient air pathway does not significantly
contribute to the unreasonable risk for DCHP for the general population. For further information, see
Section 4.3.4.
EPA expects that general population inhalation exposures from distribution in commerce would be even
lower than those for workers. Therefore, the Agency is preliminarily determining that distribution in
commerce does not significantly contribute to the unreasonable risk of DCHP.
6.2 Environment
EPA is preliminarily determining that DCHP does not present unreasonable risk of injury to the
environment. DCHP is expected to be released to the environment via air, water, biosolids, and disposal
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to landfills. The physical and chemical properties of DCHP indicate that it is not expected to be
persistent or be mobile in soils and that it has low bioaccumulation potential. Given these characteristics
and the data available, the environmental risk characterization for DCHP involved qualitative analysis of
risk to aquatic and terrestrial organisms via exposure pathways of surface water, trophic transfer,
biosolids, and landfills. EPA has robust confidence in its preliminary determination that all assessed
pathways of exposure to terrestrial animals do not significantly contribute to the unreasonable risk of
DCHP. The Agency also has robust confidence in its preliminary determination that there is no risk for
acute durations of DCHP exposure to aquatic organisms because reasonably available data found no
acute hazard effects up to and above the estimated upper bound of water solubility. EPA has
preliminarily determined that chronic exposure to aquatic animals does not significantly contribute to
the unreasonable risk of DCHP. Considerable uncertainties exist about the limit of water solubility,
water release estimates, and low-flow surface water modeling estimates. However, EPA has robust
confidence in this preliminary unreasonable risk determination because no risk was indicated under
realistic scenarios of lower water solubility, lower release estimates, more rapid stream flow, and
available measured DCHP water concentrations from the literature.
6.2.1 Populations and Exposures EPA Assessed for the Environment
EPA assessed environmental concentrations of DCHP in air, water, and land (soil, biosolids, and
groundwater) for use in environmental exposure. DCHP will preferentially sorb into sediments, soils,
particulate matter in air, and in wastewater solids during wastewater treatment. High-quality studies of
DCHP biodegradation rates and physical and chemical properties indicate that DCHP will have limited
persistence and mobility in soils receiving biosolids (U.S. EPA. 2024z) and low bioavailability in soil.
DCHP is not readily found in aquatic or terrestrial organisms and has low bioaccumulation and
biomagnification potential. Therefore, DCHP has low potential for trophic transfer through food webs
and DCHP is expected to have minimal air to soil deposition.
Surface water exposure was the only scenario where modeled concentrations could be compared with a
COC. The reasonably available studies found all acute exposure hazards to fish, invertebrates, and algae
to be higher than the water solubility limit of DCHP, so no unreasonable risk for acute exposures to
DCHP in surface water was indicated. For chronic exposures, EPA derived a COC for reproductive
effects of chronic DCHP water exposure to an aquatic invertebrate {Daphnia magna) (NITE. 2000). The
Agency EPA found no evidence that DCHP occurs in surface water at the COC of 32 |ig/L. EPA
modeled surface water concentrations and under the most conservative and least likely scenario,
estimated a high-end concentration of 165 |ig/L DCHP and a RQ greater than 1. However, all other
scenarios with more realistic release values, stream flow rates, or DCHP water solubility had RQs less
than 1. Therefore, EPA determined a low likelihood of DCHP persisting in surface waters for a long
enough duration (21 days) to cause chronic hazard in aquatic invertebrates, and thus a preliminary
determination that chronic exposure to aquatic animals does not significantly contribute to the
unreasonable risk of DCHP.
6.2.2 Summary of Environmental Effects
EPA qualitatively assessed risk via release to surface water and subsequent deposition to sediment as
well as the ambient air exposure pathway for its limited contribution via deposition to soil, water, and
sediment and is preliminarily identifying
• No adverse effects to aquatic organisms;
• No adverse effects to aquatic dependent mammals; and
• No adverse effects to terrestrial mammals.
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EPA did not conduct a quantitative modeling analysis of the trophic transfer of DCHP through food
webs because the chemical properties and fate of DCHP indicate low potential for bioaccumulation or
biomagnification. Specifically, the Agency does not expect DCHP to persist in surface water,
groundwater, or air. DCHP may persist in sediment, soil, biosolids, or landfills after release to these
environments, but DCHP's bioavailability is expected to be limited. Finally, EPA also did not find
reasonably available data sources that report the aquatic bioconcentration, aquatic bioaccumulation,
aquatic food web magnification, terrestrial biota-sediment accumulation, or terrestrial bioconcentration
of DCHP. Therefore, the Agency determined a low likelihood of DCHP transferring through food webs
thus a preliminary indication of no risk.
As explained in Section 5.3.1, EPA used a screening level approach in this draft risk evaluation using
conservative environmental release estimates for occupational COUs with the highest releases to
determine whether there is risk to the environment and the general population. The Agency first
characterized risk based upon the COU with the highest estimated concentrations for a given pathway,
based on the OES and the associated environmental media assessed in the draft risk evaluation. If this
exposure concentration did not exceed the hazard thresholds harmful to organisms, EPA based the draft
risk determination on this maximum exposure scenario to be most inclusive and protective by
encompassing the exposures from other COUs within the OES. The Agency determined that the hazard
data for fish, aquatic invertebrates, sediment-dwelling organisms, algae, terrestrial invertebrates, and
terrestrial mammals indicated no adverse effects from exposures up to and exceeding the limit of water
solubility.
EPA expects that environmental releases from distribution in commerce will be similar or less than the
exposure estimates from the COUs evaluated qualitatively, which did not exceed hazard to ecological
receptors. Therefore, the Agency has preliminarily determined that distribution in commerce also would
not result in exposures that significantly contribute to the unreasonable risk of DCHP.
EPA evaluated down-the-drain releases of DCHP for consumer COUs qualitatively. Although the
Agency acknowledges that there may be DCHP releases to the environment via the cleaning and
disposal of adhesives, sealants, paints, and coatings, EPA did not quantitatively assess down-the drain
and disposal scenarios of consumer products due to limited information from monitoring data and
limited availability of modeling tools. However, modeling tools and consideration of the physical and
chemical properties of DCHP allows the Agency to conduct a qualitative assessment. DCHP is expected
to be persistent as it leaches from consumer products disposed of in landfills. Due to low water
solubility, DCHP is likely to be present in landfill leachate up to its aqueous limit of solubility.
However, due to its affinity for organic carbon, DCHP is expected to be immobile in groundwater, and
even in cases where landfill leachate containing DCHP were to migrate to groundwater, DCHP would
likely partition from groundwater to organic carbon present in the subsurface. Therefore, EPA is
preliminarily determining that the consumer COUs do not significantly contribute to the unreasonable
risk of DCHP due to down-the-drain releases.
^2.3 Basis for No Unreasonable Risk of Injury to the Environment
Based on the draft risk evaluation for DCHP—including the risk estimates, the environmental effects of
DCHP, the exposures, physical and chemical properties of DCHP, and consideration of uncertainties—
EPA did not identify risk of injury to the environment that would significantly contribute to the
unreasonable risk determination for DCHP. For aquatic organisms, surface water was determined to be
the driver of exposure, but the Agency does not expect this pathway to significantly contribute to
unreasonable risk to the environment. EPA does not expect exposure to DCHP via water, land, or
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dietary pathways to significantly contribute to unreasonable risk to the environment. The overall
confidence in the preliminary risk characterizations for aquatic and terrestrial assessments is robust.
6.3 Additional Information Regarding the Basis for Unreasonable Risk
Table 6-3 summarizes the basis for this unreasonable risk determination of injury to human health
presented in this draft DCHP risk evaluation. In these tables, a checkmark (•/) indicates how the COU
significantly contributes to the unreasonable risk by identifying the type of effect (e.g., non-cancer for
human health) and the exposure route to the population that results in such significant contribution. As
explained in Section 6.1, for this draft unreasonable risk determination, EPA has considered the effects
of DCHP to human health at the central tendency and high-end, as well as effects of DCHP to human
health and the environment from the exposures associated with the COU, risk estimates, and
uncertainties in the analysis. In addition, certain exposure routes for some COUs were not assessed
because it was determined that there was no viable exposure pathway. These COUs and their respective
exposure routes are grayed-out in Table 6-3. Checkmarks in Table 6-3 represent risk at the high-end and
central tendency exposure level as discussed in Section 6.1. See Sections 4.3 and 5.3 for a summary of
risk estimates.
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4536 Table 6-3. Supporting Basis for the Draft Unreasonable Risk Determination for Human Health" (Occupational CPUs)
Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
Manufacturing
Domestic
manufacturing
Domestic manufacturing
Average Adult
Worker
Dermal
Inhalation
Aggregate
Female Worker of
Reproductive Age c
Dermal
Inhalation
V
Aggregate
•/
ONU
Dermal
Inhalation
Importing
Importing
Average Adult
Worker
Dermal
Inhalation
Aggregate
Female Worker of
Reproductive Age
Dermal
Inhalation
Aggregate
ONU
Dermal
Inhalation
Processing -
incorporation into
formulation,
mixture, or
reaction product
Adhesive and sealant chemicals in:
- Adhesive Manufacturing
Average Adult
Worker
Dermal
Inhalation
Aggregate
Female Worker of
Reproductive Age
Dermal
Inhalation
¦/
Aggregate
ONU
Dermal
Inhalation
Plasticizer in:
-Adhesive manufacturing
- Paint and coating manufacturing
- Printing ink manufacturing
Average Adult
Worker
Dermal
Inhalation
Aggregate
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Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
Female Worker of
Reproductive Age
Dermal
Plasticizer in:
Inhalation
V
-Adhesive manufacturing
- Paint and coating manufacturing
- Printing ink manufacturing
Aggregate
V
ONU
Dermal
Inhalation
Dermal
Average Adult
Worker
Inhalation
Plasticizer in:
- Plastic material and resin manufacturing
Aggregate
Female Worker of
Reproductive Age
Dermal
- Plastics product manufacturing
- Rubber product manufacturing
Inhalation
Aggregate
ONU
Dermal
Processing -
incorporation into
formulation,
mixture, or
Inhalation
Processing
Average Adult
Worker
Dermal
Inhalation
reaction product
Stabilizing agent in:
Aggregate
- Adhesive manufacturing
- Asphalt paving, roofing, and coating
materials manufacturing
Female Worker of
Reproductive Age
Dermal
Inhalation
V
- Paint and coating manufacturing
Aggregate
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Stabilizing agent in:
Aggregate
- Plastics product manufacturing
Female Worker of
Reproductive Age
Dermal
Inhalation
Aggregate
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Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Aggregate
Processing -
incorporation into
article
Plasticizer in:
- Plastics product manufacturing
- Rubber product manufacturing
Female Worker of
Reproductive Age
Dermal
Inhalation
Aggregate
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Processing
Aggregate
Repackaging
Repackaging (e.g., laboratory chemical)
Dermal
Female Worker of
Reproductive Age
Inhalation
Aggregate
ONU
Dermal
Inhalation
Dermal
Average Adult
Worker
Inhalation
Aggregate
Female Worker of
Reproductive Age
Dermal
Recycling
Recycling
Inhalation
Aggregate
Dermal
ONU
Inhalation
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Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
Worker
Dermal
Distribution in
Distribution in
Distribution in commerce
Inhalation
Commerce
Commerce
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Aggregate
Adhesive and
Adhesives and sealants (e.g., computer
and electronic product manufacturing;
transportation equipment manufacturing)
Female Worker of
Reproductive Age
Dermal
sealants
Inhalation
Aggregate
ONU
Dermal
Inhalation
Dermal
Average Adult
Worker
Inhalation
Aggregate
Industrial Use
Finishing agent
Cellulose film production
Female Worker of
Reproductive Age
Dermal
Inhalation
V
Aggregate
V
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Aggregate
Inks, toner, and
colorant products
Inks, toner, and colorant products (e.g.,
screen printing ink)
Dermal
Female Worker of
Reproductive Age
Inhalation
V
Aggregate
¦/
ONU
Dermal
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Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
Inhalation
Dermal
Average Adult
Worker
Inhalation
Aggregate
Paints and coatings
Paints and coatings
Female Worker of
Reproductive Age
Dermal
Inhalation
V
Aggregate
V
Industrial Use
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Other articles with
routine direct
Inhalation
Other articles with routine direct contact
during normal use including rubber
Aggregate
contact during
normal use
including rubber
Female Worker of
Reproductive Age
Dermal
articles; plastic articles (hard) (e.g.,
transportation equipment manufacturing)
Inhalation
articles; plastic
articles (hard)
Aggregate
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Aggregate
Adhesives and
Adhesives and sealants
Female Worker of
Reproductive Age
Dermal
sealants
Inhalation
Commercial Use
Aggregate
ONU
Dermal
Inhalation
Building/construction materials not
Average Adult
Dermal
covered elsewhere
Worker
Inhalation
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Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
Aggregate
Female Worker of
Reproductive Age
Dermal
Building/constructi
on materials not
covered elsewhere
Inhalation
Aggregate
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Aggregate
Inks, toner, and
Inks, toner, and colorant products (e.g.,
Female Worker of
Reproductive Age
Dermal
colorant products
screen printing ink)
Inhalation
V
Aggregate
V
ONU
Dermal
Commercial Use
Inhalation
Average Adult
Worker
Dermal
Inhalation
Aggregate
Laboratory
Laboratory chemicals
Female Worker of
Reproductive Age
Dermal
chemicals
Inhalation
Aggregate
ONU
Dermal
Inhalation
Average Adult
Worker
Dermal
Inhalation
Paints and coatings
Paints and coatings
Aggregate
Female Worker of
Dermal
Reproductive Age
Inhalation
V
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Life Cycle
Stage
Category
Subcategory
Population
Exposure
Route b
Acute
Life Cycle
Stage
Category
Commercial Use
Aggregate
V
ONU
Dermal
Inhalation
Other articles with
routine direct
contact during
normal use
including rubber
articles; plastic
articles (hard)
Other articles with routine direct contact
during normal use including rubber
articles; plastic articles (hard)
Average Adult
Worker
Dermal
Inhalation
Aggregate
Female Worker of
Reproductive Age
Dermal
Inhalation
Aggregate
ONU
Dermal
Inhalation
Disposal
Disposal
Disposal
Average Adult
Worker
Dermal
Inhalation
Aggregate
Female Worker of
Reproductive Age
Dermal
Inhalation
Aggregate
ONU
Dermal
Inhalation
" Grayed-out boxes indicate certain exposure routes that were not assessed because it was determined that there was no viable exposure pathway.
b Inhalation, dermal, and aggregate risk estimates were generated for each COU for workers (average adult and women of reproductive age) and ONUs if it was
determined that there was a viable exposure pathway.
c EPA analyzed and presented risk for female workers of reproductive age, which are a subset of the average adult worker population, separately due to the greater
susceptibility of developing fetuses to adverse health effects from phthalate exposure.
4537
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December 2024
U.S. EPA. (2004c). Spray coatings in the furniture industry - generic scenario for estimating
occupational exposures and environmental releases.
U.S. EPA. (2004d). Spray coatings in the furniture industry - generic scenario for estimating
occupational exposures and environmental releases: Draft. Washington, DC.
https://www.epa.gov/tsca-screening-tools/using-predictive-methods-assess-exposure-and-fate-
under-tsca
U.S. EPA. (2006). A framework for assessing health risk of environmental exposures to children.
(EPA/600/R-05/093F). Washington, DC: U.S. Environmental Protection Agency, Office of
Research and Development, National Center for Environmental Assessment.
http://cfpub.epa. gov/ncea/cfm/recordisplav.cfm?deid=l 58363
U.S. EPA. (2007). Concepts, methods, and data sources for cumulative health risk assessment of
multiple chemicals, exposures, and effects: A resource document [EPA Report], (EPA/600/R-
06/013F). Cincinnati, OH. http://cfpub.epa. gov/ncea/cfm/recordisplay.cfm?deid= 190187
U.S. EPA. (2010). Manufacture and use of printing inks - generic scenario for estimating occupational
exposures and environmental releases: Draft. Washington, DC. https://www.epa.gov/tsca-
screening-tools/chemsteer-chemical-screening-tool-exposures-and-environmental-
releases#genericscenarios
U.S. EPA. (201 la). Exposure factors handbook: 2011 edition [EPA Report], (EPA/600/R-090/052F).
Washington, DC: U.S. Environmental Protection Agency, Office of Research and Development,
National Center for Environmental Assessment.
https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockev=P 100F2QS.txt
U.S. EPA. (201 lb). Exposure factors handbook: 2011 edition (final) (EPA/600/R-090/052F).
Washington, DC. http://cfpub.epa.gov/ncea/cfm/recordisplav.cfm?deid=236252
U.S. EPA. (2011c). Recommended use of body weight 3/4 as the default method in derivation of the oral
reference dose. (EPA100R110001). Washington, DC.
https://www.epa.gov/sites/production/files/2013-09/documents/recommended-use-of-bw34.pdf
U.S. EPA. (2012). Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11 [Computer
Program], Washington, DC. Retrieved from https://www.epa.gov/tsca-screening-tools/epi-
suitetm-estimation-program-interface
U.S. EPA. (2014a). Formulation of waterborne coatings - Generic scenario for estimating occupational
exposures and environmental releases -Draft. Washington, DC. https://www.epa.gov/tsca-
screening-tools/using-predictive-methods-assess-exposure-and-fate-under-tsca
U.S. EPA. (2014b). Generic scenario on coating application via spray painting in the automotive
refinishing industry.
U.S. EPA. (2014c). Use of additive in plastic compounding - generic scenario for estimating
occupational exposures and environmental releases: Draft. Washington, DC.
https://www.epa.gov/tsca-screening-tools/using-predictive-methods-assess-exposure-and-fate-
under-tsca
U.S. EPA. (2016a). Guidance for conducting fish consumption surveys. (823B16002).
https://www.epa.gov/sites/production/files/2017-01/documents/fc survey guidance.pdf
U.S. EPA. (2016b). Pesticide cumulative risk assessment: Framework for screening analysis.
Washington, DC: Office of Pesticide Programs, https://www.epa.gov/pesticide-science-and-
assessing-pesticide-risks/pesticide-cumulative-risk-assessment-framework
U.S. EPA. (2017). Estimation Programs Interface Suite™ v.4.11. Washington, DC: U.S. Environmental
Protection Agency, Office of Pollution Prevention Toxics. Retrieved from
https://www.epa.gov/tsca-screening-tools/download-epi-suitetm-estimation-program-interface-
v411
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U.S. EPA. (2019a). Chemical data reporting (2012 and 2016 public CDR database). Washington, DC:
U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics. Retrieved
from https://www.epa.gov/chemical-data-reporting
U.S. EPA. (2019b). Guidelines for human exposure assessment [EPA Report], (EPA/100/B-19/001).
Washington, DC: Risk Assessment Forum, https://www.epa.gov/sites/production/files/2020-
01/documents/guidelines for human exposure assessment final2019.pdf
U.S. EPA. (2019c). Meeting summary with Nouryon and EPA to discuss conditions of use for
dicyclohexyl phthalate. Washington, DC. https://www.regulations.gov/document/EPA-HQ-
QPPT-2018-0504-0017
U.S. EPA. (2019d). Meeting with Carboline and EPA to discuss conditions of use for dicyclohexyl
phthalate. Washington, DC. https://www.regulations.gov/document/EPA-HQ-OPPT-2018-05Q4-
0018
U.S. EPA. (2019e). Meeting with Vertellus and EPA to discuss conditions of use for dicyclohexyl
phthalate. Washington, DC. https://www.regulations.gov/document/EPA-HQ-OPPT-2018-0504-
0021
U.S. EPA. (2020a). 2020 CDR data [Database], Washington, DC: U.S. Environmental Protection
Agency, Office of Pollution Prevention and Toxics. Retrieved from
https://www.epa.gov/chemical-data-reporting/access-cdr-data
U.S. EPA. (2020b). Final scope of the risk evaluation for dicyclohexyl phthalate (1,2-
benzenedicarboxylic acid, 1,2-dicyclohexyl ester); CASRN 84-61-7 [EPA Report], (EPA-740-R-
20-019). Washington, DC: Office of Chemical Safety and Pollution Prevention.
https://www.epa.gov/sites/default/files/2020-09/documents/casrn 84-61-
7 dicyclohexyl phthalate final scope.pdf
U.S. EPA. (2020c). Meeting with EPA and Futamura USA to discuss conditions of use for dicyclohexyl
phthalate. Washington, DC. https://www.regulations.gov/comment/EPA-HQ-OPPT-2018-0504-
0045
U.S. EPA. (2020d). Phone call with Sigma-Aldrich: 1/6/20 [Personal Communication],
https://www.regulations.gov/comment/EPA-HQ-OPPT-2018-0504-0019
U.S. EPA. (2021a). Draft systematic review protocol supporting TSCA risk evaluations for chemical
substances, Version 1.0: A generic TSCA systematic review protocol with chemical-specific
methodologies. (EPA Document #EPA-D-20-031). Washington, DC: Office of Chemical Safety
and Pollution Prevention, https://www.regulations. gov/document/EPA-HQ-QPPT-2021 -0414-
0005
U.S. EPA. (2021b). Generic model for central tendency and high-end inhalation exposure to total and
respirable Particulates Not Otherwise Regulated (PNOR). Washington, DC: Office of Pollution
Prevention and Toxics, Chemical Engineering Branch.
U.S. EPA. (2021c). Meeting summary with LANXESS 09-20-2021: Di-isobutyl Phthalate (DIBP)
Consortium representatives and EPA to discuss uses of di-isobutyl phthalate and dicyclohexyl
phthalate. Washington, DC. https://www.regulations.gov/document/EPA-HQ-OPPT-2018-0434-
0053
U.S. EPA. (202Id). Use of additives in plastic compounding - Generic scenario for estimating
occupational exposures and environmental releases (Revised draft) [EPA Report], Washington,
DC: Office of Pollution Prevention and Toxics, Risk Assessment Division.
U.S. EPA. (202le). Use of additives in plastics converting - Generic scenario for estimating
occupational exposures and environmental releases (revised draft). Washington, DC: Office of
Pollution Prevention and Toxics.
U.S. EPA. (2022a). Chemical repackaging - Generic scenario for estimating occupational exposures and
environmental releases (revised draft) [EPA Report], Washington, DC.
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U.S. EPA. (2022b). Draft TSCA screening level approach for assessing ambient air and water exposures
to fenceline communities (version 1.0) [EPA Report], (EPA-744-D-22-001). Washington, DC:
Office of Chemical Safety and Pollution Prevention, U.S. Environmental Protection Agency.
https://heronet.epa.gov/heronet/index.cfm/reference/download/reference id/10555664
U.S. EPA. (2022c). ORD staff handbook for developing IRIS assessments [EPA Report], (EPA 600/R-
22/268). Washington, DC: U.S. Environmental Protection Agency, Office of Research and
Development, Center for Public Health and Environmental Assessment.
https://cfpub.epa.gov/ncea/iris drafts/recordisplav.cfm?deid=356370
U.S. EPA. (2023a). Advances in dose addition for chemical mixtures: A white paper. (EPA/100/R-
23/001). Washington, DC. https://assessments.epa.gov/risk/document/&deid=359745
U.S. EPA. (2023b). Consumer Exposure Model (CEM) Version 3.2 User's Guide. Washington, DC.
https://www.epa.gov/tsca-screening-tools/consumer-exposure-model-cem-version-32-users-
guide
U.S. EPA. (2023c). Draft Proposed Approach for Cumulative Risk Assessment of High-Priority
Phthalates and a Manufacturer-Requested Phthalate under the Toxic Substances Control Act.
(EPA-740-P-23-002). Washington, DC: U.S. Environmental Protection Agency, Office of
Chemical Safety and Pollution Prevention. https://www.regulations.gov/document/EPA-HQ-
QPPT-2022-0918-0009
U.S. EPA. (2023d). Draft Proposed Principles of Cumulative Risk Assessment under the Toxic
Substances Control Act. (EPA-740-P-23-001). Washington, DC: U.S. Environmental Protection
Agency, Office of Chemical Safety and Pollution Prevention.
https://www.regulations.gov/document/EPA-HO-OPPT-2022-0918-00Q8
U.S. EPA. (2023e). Methodology for estimating environmental releases from sampling waste (revised
draft). Washington, DC: Office of Pollution Prevention and Toxics, Chemical Engineering
Branch.
U.S. EPA. (2023f). Science Advisory Committee on Chemicals meeting minutes and final report, No.
2023-01 - A set of scientific issues being considered by the Environmental Protection Agency
regarding: Draft Proposed Principles of Cumulative Risk Assessment (CRA) under the Toxic
Substances Control Act and a Draft Proposed Approach for CRA of High-Priority Phthalates and
a Manufacturer-Requested Phthalate. (EPA-HQ-OPPT-2022-0918). Washington, DC: U.S.
Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention.
https://www.regulations.gov/document/EPA-HO-OPPT-2022-0918-0Q67
U.S. EPA. (2023 g). Use of laboratory chemicals - Generic scenario for estimating occupational
exposures and environmental releases (Revised draft generic scenario) [EPA Report],
Washington, DC: U.S. Environmental Protection Agency, Office of Pollution Prevention and
Toxics, Existing Chemicals Risk Assessment Division.
U.S. EPA. (2024a). Draft Ambient Air Exposure Assessment for Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024b). Draft Cancer Human Health Hazard Assessment for Di(2-ethylhexyl) Phthalate
(DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl Phthalate (DIBP),
and Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and
Toxics.
U.S. EPA. (2024c). Draft Consumer and Indoor Dust Exposure Assessment for Dicyclohexyl Phthalate
(DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024d). Draft Consumer Exposure Analysis for Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024e). Draft Consumer Risk Calculator for Dicyclohexyl Phthalate (DCHP). Washington,
DC: Office of Pollution Prevention and Toxics.
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U.S. EPA. (2024f). Draft Data Extraction Information for Environmental Hazard and Human Health
Hazard Animal Toxicology and Epidemiology for Dicyclohexyl Phthalate (DCHP). Washington,
DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024g). Draft Data Extraction Information for General Population, Consumer, and
Environmental Exposure for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of
Pollution Prevention and Toxics.
U.S. EPA. (2024h). Draft Data Quality Evaluation and Data Extraction Information for Environmental
Fate and Transport for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution
Prevention and Toxics.
U.S. EPA. (2024i). Draft Data Quality Evaluation and Data Extraction Information for Environmental
Release and Occupational Exposure for Dicyclohexyl Phthalate (DCHP). Washington, DC:
Office of Pollution Prevention and Toxics.
U.S. EPA. (2024i). Draft Data Quality Evaluation and Data Extraction Information for Physical and
Chemical Properties for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution
Prevention and Toxics.
U.S. EPA. (2024k). Draft Data Quality Evaluation Information for Environmental Hazard for
Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (20241). Draft Data Quality Evaluation Information for General Population, Consumer, and
Environmental Exposure for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of
Pollution Prevention and Toxics.
U.S. EPA. (2024m). Draft Data Quality Evaluation Information for Human Health Hazard Animal
Toxicology for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution
Prevention and Toxics.
U.S. EPA. (2024n). Draft Data Quality Evaluation Information for Human Health Hazard Epidemiology
for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and
Toxics.
U.S. EPA. (2024o). Draft Environmental Hazard Assessment for Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024p). Draft Environmental Media and General Population and Environmental Exposure
for Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and
Toxics.
U.S. EPA. (2024q). Draft Environmental Release and Occupational Exposure Assessment for
Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024r). Draft Fish Ingestion Risk Calculator for Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024s). Draft Meta-Analysis and Benchmark Dose Modeling of Fetal Testicular
Testosterone for Di(2-ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl
Phthalate (BBP), Diisobutyl Phthalate (DIBP), and Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024t). Draft Non-cancer Human Health Hazard Assessment for Butyl benzyl phthalate
(BBP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024u). Draft Non-cancer Human Health Hazard Assessment for Dibutyl Phthalate (DBP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024v). Draft Non-Cancer Human Health Hazard Assessment for Dicyclohexyl Phthalate
(DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024w). Draft Non-cancer Human Health Hazard Assessment for Diethylhexyl Phthalate
(DEHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024x). Draft Non-cancer Human Health Hazard Assessment for Diisobutyl phthalate
(DIBP). Washington, DC: Office of Pollution Prevention and Toxics.
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December 2024
U.S. EPA. (2024y). Draft Occupational and Consumer Cumulative Risk Calculator for Dicyclohexyl
Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024z). Draft physical chemistry and fate and transport assessment for dicyclohexyl
phthalate (DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024aa). Draft Physical Chemistry Assessment for Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024ab). Draft Risk Calculator for Occupational Exposures for Dicyclohexyl Phthalate
(DCHP). Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024ac). Draft Summary of Facility Release Data for Di(2-ethylhexyl) Phthalate (DEHP),
Dibutyl Phthalate (DBP), and Butyl Benzyl Phthalate (BBP). Washington, DC: Office of
Pollution Prevention and Toxics.
U.S. EPA. (2024ad). Draft Surface Water Human Exposure Risk Calculator for Dicyclohexyl Phthalate
(DCHP) for P50 Flow Rates. Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024ae). Draft Surface Water Human Exposure Risk Calculator for Dicyclohexyl Phthalate
(DCHP) for P75 Flow Rates. Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024af). Draft Surface Water Human Exposure Risk Calculator for Dicyclohexyl Phthalate
(DCHP) for P90 Flow Rates. Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024ag). Draft Systematic Review Protocol for Dicyclohexyl Phthalate (DCHP).
Washington, DC: Office of Pollution Prevention and Toxics.
U.S. EPA. (2024ah). Draft Technical Support Document for the Cumulative Risk Analysis of Di(2-
ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP),
Diisobutyl Phthalate (DIBP), Dicyclohexyl Phthalate (DCHP), and Diisononyl Phthalate (DINP)
Under the Toxic Substances Control Act (TSCA). Washington, DC: Office of Chemical Safety
and Pollution Prevention.
U.S. EPA. (2024ai). Environmental Media and General Population Screening for Diisononyl Phthalate
(DINP). Washington, DC: Office of Pollution Prevention and Toxics.
https://www.regulations.gov/docket/EPA-HQ-OPPT-2018-0436
U.S. EPA. (2024ai). Meeting summary with Nouryon and EPA to discuss conditions of use for
dicyclohexyl phthalate. Washington, DC.
U.S. EPA. (2025a). Draft Cancer Human Health Hazard Assessment for Di(2-ethylhexyl) Phthalate
(DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl Phthalate (DIBP),
and Dicyclohexyl Phthalate (DCHP). Washington, DC: Office of Pollution Prevention and
Toxics.
U.S. EPA. (2025b). Non-Cancer Human Health Hazard Assessment for Diisononyl Phthalate (DINP)
Washington, DC: Office of Pollution Prevention and Toxics.
Versar. (2014). Exposure and Fate Assessment Screening Tool (E-FAST 2014) - Documentation
manual. Washington, DC: U.S. Environmental Protection Agency, https://www.epa.gov/tsca-
screening-tools/e-fast-exposure-and-fate-assessment-screening-tool-version-2014
Vertellus LLC. (2020). Comment submitted by Misty L. Bogle, Global Director, Regulatory
Management, Vertellus LLC regarding the Draft Scope of the Risk Evaluation for Dicyclohexyl
Phthalate (l,2Benzenedicarboxylic acid, 1,2-dicyclohexyl ester). Indianapolis, IN: Vertellus
LLC. https://www.regulations.gov/comment/EPA-HO-OPPT-2018-0504-0Q43
WA DOE. (2022). Survey of phthalates in Washington State waterbodies, 2021. (Publication 22-03-
027). Olympia, WA. https://apps.ecologv.wa.gov/publications/documents/2203027.pdf
Wu, J: Ma. T; Zhou. Z; Yu. Na: He. Z; Li. B; Shi. Y; Ma. D. (2019). Occurrence and fate of phthalate
esters in wastewater treatment plants in Qingdao, China. Hum Ecol Risk Assess 25: 1547-1563.
http://dx.doi.org/10.1080/10807039.2Q18.1471341
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APPENDICES
Appendix A KEY ABBREVIATIONS AND ACRONYMS
ADD
Average daily dose
ADC
Average daily concentration
BBP
Butyl benzyl phthalate
BLS
Bureau of Labor Statistics
CASRN
Chemical Abstracts Service Registry Number
CBI
Confidential business information
CDR
Chemical Data Reporting
CEHD
Chemical Exposure Health Data
CEM
Consumer Exposure Model
CFR
Code of Federal Regulations
COC
Concentration of concern
CPSC
Consumer Product Safety Commission
CRA
Cumulative risk assessment
DBP
Dibutyl phthalate
DCHP
Dicyclohexyl phthalate
DEHP
Diethylhexyl phthalate
DIBP
Diisobutyl phthalate
DIDP
Diisodecyl phthalate
DINP
Dicyclohexyl phthalate
DIY
Do-it-yourself
EPA
Environmental Protection Agency
ESD
Emission scenario document
EU
European Union
FDA
Food and Drug Administration
GS
Generic scenario
Koc
Soil organic carbon: water partitioning coefficient
Kow
Octanol: water partition coefficient
HEC
Human equivalent concentration
HED
Human equivalent dose
IADD
Intermediate average daily dose
IR
Ingestion rate
LCD
Life cycle diagram
LOAEL
Lowest-observed-adverse-effect level
Log Koc
Logarithmic organic carbon: water partition coefficient
Log Kow
Logarithmic octanol: water partition coefficient
MOA
Mode of action
MOE
Margin of exposure
NAICS
North American Industry Classification System
NHANES
National Health and Nutrition Examination Survey
NICNAS
National Industrial Chemicals Notification and Assessment Scheme
NOAEL
No-observed-adverse-effect level
NPDES
National Pollutant Discharge Elimination System
OCSPP
Office of Chemical Safety and Pollution Prevention
OECD
Organisation for Economic Co-operation and Development
OES
Occupational exposure scenario
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5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
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OEV
Occupational exposure value
ONU
Occupational non-user
OPPT
Office of Pollution Prevention and Toxics
OSHA
Occupational Safety and Health Administration
PBZ
Personal breathing zone
PESS
Potentially exposed or susceptible subpopulations
PND
Postnatal day
PNOR
Particulates not otherwise regulated
POD
Point of departure
PV
Production volume
PVC
Polyvinyl chloride
RPF
Relative potency factor
RQ
Risk quotient
SACC
Science Advisory Committee on Chemicals
SDS
Safety data sheet
SOC
Standard occupational classification
SpERC
Specific emission release category
TRI
Toxic Release Inventory
TRV
Toxicity reference value
TSCA
Toxic Substances Control Act
TSD
Technical support document
TWA
Time-weighted average
UF
Uncertainty factor
U.S.
United States
WWTP
Wastewater treatment plant
7Q10
The lowest 7-day average flow that occurs (on average) once every 10 years
30Q5
The lowest 30-day average flow that occurs (on average) once every 5 years
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5191 Appendix B REGULATORY AND ASSESSMENT HISTORY
5192 B.l Federal Laws and Regulations
5193
Table Apx B-l. Federa
Laws and Regulations
Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
EPA statutes/regulations
Toxic Substances Control
Act (TSCA) - section
6(b)
EPA is directed to identify high-priority
chemical substances for risk evaluation;
and conduct risk evaluations on at least
20 high priority substances no later than
3.5 years after the date of enactment of
the Frank R. Lautenberg Chemical Safety
for the 21st Century Act.
DCHP is one of the 20 chemicals EPA
designated as a high-priority substance for
risk evaluation under TSCA (84 FR 71924.
December 30, 2019). Designation of DCHP
as high-priority substance constitutes the
initiation of the risk evaluation on the
chemical.
Toxic Substances Control
Act (TSCA) - section
8(a)
The TSCA section 8(a) CDR Rule
requires manufacturers (including
importers) to give EPA basic exposure-
related information on the types,
quantities, and uses of chemical
substances produced domestically and
imported into the United States.
DCHP manufacturing (including
importing), processing and use information
is reported under the CDR rule (85 FR
20122. Aoril 9. 2020).
Toxic Substances Control
Act (TSCA) - section
8(b)
EPA must compile, keep current and
publish a list (the TSCA Inventory) of
each chemical substance manufactured
(including imported) or processed in the
United States.
DCHP was on the initial TSCA Inventory
and therefore was not subject to EPA's new
chemicals review process under TSCA
Section 5 (60 FR 16309. March 29. 1995).
Clean Water Act (CWA)
- sections 301, 304, 306,
307, and 402
Clean Water Act section 307(a)
established a list of toxic pollutants or
combination of pollutants under the
CWA. The statute specifies a list of
families of toxic pollutants also listed in
the Code of Federal Regulations at 40
CFR part 401.15. The "priority
pollutants" specified by those families are
listed in 40 CFR part 423 Appendix A.
These are pollutants for which best
available technology effluent limitations
must be established on either a national
basis through rules (sections 301(b),
304(b), 307(b), 306) or on a case-by-case
best professional judgement basis in
NPDES permits, see section
402(a)(1)(B). EPA identifies the best
available technology that is economically
achievable for that industry after
considering statutorily prescribed factors
and sets regulatory requirements based on
the performance of that technology.
As a phthalate ester, DCHP is designated as
atoxic pollutant under section 307(a)(1) of
the CWA, and as such is subject to effluent
limitations (40 CFR 401.15).
Other federal statutes/regulations
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Statutes/Regulations
Description of Authority/Regulation
Description of Regulation
Federal Food, Drug, and
Cosmetic Act (FFDCA)
Provides the Food and Drug
Administration (FDA) with authority to
oversee the safety of food, drugs, and
cosmetics, except residues of pesticides
in food are regulated by EPA under
FFDCA section 408 (discussed above
where applicable).
DCHP is listed as an optional substance to
be used in: adhesives to be used as
components of articles intended for use, in
accordance with prescribed conditions, in
packaging, transporting, or holding food
(21 CFR section 175.105); the base sheet
and coating of cellophane (21 CFR section
177.1200); plasticizers in polvmeric
substances (21 CFR section 178.3740).
Consumer Product Safety
Improvement Action of
2008 (CPSIA)
Under section 108 of the Consumer
Product Safety Improvement Act of 2008
(CPSIA), CPSC prohibits the
manufacture for sale, offer for sale,
distribution in commerce or importation
of eight phthalates in toys and childcare
articles at concentrations >0.1%: DEHP,
DBP, BBP, DINP, DIBP, DPENP,
DHEXP and DCHP.
The use of DCHP at concentrations >0.1%
is banned in toys and childcare articles (16
CFR nart 1307).
5195 B.2 State Laws and Regulations
5196
5197 Table Apx B-2. State Laws and Regulations
State Actions
Description of Action
Chemicals of High
Concern to Children
Several states have adopted reporting laws for chemicals in children's products
containing DCHP. including Maine (38 MRSA Chapter 16-D) and Washington State
(Wash. Admin. Code 173-334-130).
Other
DCHP is listed as a Candidate Chemical under California's Safer Consumer
Products Program established under Health and Safety Code section 25252 and
25253 (California. Candidate Chemical List. Accessed April 16. 2019). California
lists DCHP as a designated priority chemical for biomonitoring under criteria
established bv California SB 1379 (Biomonitorina California. Priority Chemicals.
February 2019). Oregon lists DCHP as a toxic air contaminant (OAR 340-245-8020
Table 2).
5198 B.3 International Laws and Regulations
5199
5200 Table Apx B-3. International Laws and Regulations
Country/ Organization
Requirements and Restrictions
European Union
On June 27. 2018. DCHP was listed on the Candidate List as a Substance of Verv High
Concern (SVHC) under regulation (EC) No 1907/2006 - REACH (Registration,
Evaluation, Authorization and Restriction of Chemicals because it is toxic for
reproduction (Article 57(c) and has endocrine disrupting properties (Article 57(f) -
human health). DCHP was evaluated under the 2017 Community rolling action plan
(CoRAP) under regulation (European Commission [EC]) Nol907/2006 - REACH
(Registration. Evaluation. Authorization and Restriction of Chemicals) (European
Chemicals Agencv (ECHA) database. Accessed April 16. 2019).
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Country/ Organization
Requirements and Restrictions
Australia
DCHP was assessed under Human Health Tier II of the Inventory Multi-Tiered
Assessment and Prioritization (IMAP) as part of the C4-6 side chain transitional
phthalates. Uses reported include in adhesives and printing inks (NICNAS, 2016,
Human Health Tier II assessment for C4-6 side chain transitional phthalates). In
addition, DCHP was assessed under Environment Tier II of IMAP as part of the
phthalate esters. In 2015, DCHP was also assessed as a Priority Existing Chemical
(Assessment Report No. 40) (National Industrial Chemicals Notification and
Assessment Scheme (NICNAS). Chemical inventory. Database accessed April 3. 2019).
Japan
DCHP is regulated in Japan under the following legislation:
• Act on the Evaluation of Chemical Substances and Regulation of Their
Manufacture, etc. (Chemical Substances Control Law; CSCL)
• Act on Confirmation, etc. of Release Amounts of Specific Chemical Substances in
the Environment and Promotion of Improvements to the Management Thereof.
(National Institute of Technoloav and Evaluation fNITEl Chemical Risk Information
Platform TCHRIPl. Accessed April 16, 2019).
Austria, Denmark,
Ireland, New Zealand,
United Kingdom
Occupational exposure limits for DCHP (GESTIS International limit values for
chemical aaents (Occupational exposure limits. OELs) database. Accessed April 18.
2017). Austria, Ireland, New Zealand and the United Kingdom have an eight-hours limit
of 5 mg/m3. Denmark has an eight-hours limit of 3 mg/m3 and a short-term limit of 6
mg/m3.
5201 B.4 Assessment History
5202
5203 Table Apx B-4. Assessment History of DCHP
Authoring Organization
Publication
U.S. EPA publications
-
-
Other U.S.-based organizations
U.S. Consumer Product Safety Commission (CPSC)
Chronic Hazard Panel on Phthalates and Phthalate
Alternatives Final Report (with Appendices) (U.S.
CPSC. 2014)
Toxicity Review of DCHP (U.S. CPSC. 2010)
International
European Union, European Chemicals Agency (ECHA)
Committee for Risk Assessment RAC Opinion
proposing harmonised classification and labelling at
EU level of DCHP, EC number: 201-545-9, CAS
number: 84-61-7 (ECHA. 2014)
Government of Canada, Environment Canada, Health
Canada
Screening Assessment: Phthalate Substance Grouping
(ECCC/HC. 2020)
State of the science report: Phthalate substance
grouping: Medium-chain phthalate esters: Chemical
Abstracts Service Registry Numbers: 84-61-7; 84-64-
0; 84-69-5; 523-31-9; 5334-09-8;16883-83-3; 27215-
22-1: 27987-25-3: 68515-40-2: 71888-89-6 (EC/HC.
2015)
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Authoring Organization
Publication
National Industrial Chemicals Notification and
Assessment Scheme (NICNAS), Australian
Government
C4-6 side chain transitional phthalates: Human health
tier II assessment (NICNAS. 2016)
Phthalates hazard compendium: A summary of
physicochemical and human health hazard data for 24
ortho-phthalate chemicals (NICNAS. 2008)
5204
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5222
5223
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5228
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5235
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Appendix C LIST OF TECHNICAL SUPPORT DOCUMENTS
Appendix C incudes a list and citations for all supplemental documents included in the Draft Risk
Evaluation for DCHP.
Associated Systematic Review Protocol and Data Quality Evaluation and Data Extraction
Documents - Provide additional detail and information on systematic review methodologies used as
well as the data quality evaluations and extractions criteria and results.
Draft Systematic Review Protocol for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024ag) - In lieu
of an update to the Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for
Chemical Substances, also referred to as the "2021 Draft Systematic Review Protocol" (U.S. EPA.
2021a). this systematic review protocol for the Draft Risk Evaluation for DCHP describes some
clarifications and different approaches that were implemented than those described in the 2021 Draft
Systematic Review Protocol in response to (1) SACC comments, (2) public comments, or (3) to
reflect chemical-specific risk evaluation needs. This supplemental file may also be referred to as the
"DCHP Systematic Review Protocol."
Draft Data Quality Evaluation and Data Extraction Information for Physical and Chemical
Properties for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024i) - Provides a compilation of tables
for the data extraction and data quality evaluation information for DCHP. Each table shows the data
point, set, or information element that was extracted and evaluated from a data source that has
information relevant for the evaluation of physical and chemical properties. This supplemental file
may also be referred to as the "DCHP Data Quality Evaluation and Data Extraction Information for
Physical and Chemical Properties."
Draft Data Quality Evaluation and Data Extraction Information for Environmental Fate and
Transport for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024h) - Provides a compilation of tables
for the data extraction and data quality evaluation information for DCHP. Each table shows the data
point, set, or information element that was extracted and evaluated from a data source that has
information relevant for the evaluation for Environmental Fate and Transport. This supplemental file
may also be referred to as the "DCHP Data Quality Evaluation and Data Extraction Information for
Environmental Fate and Transport."
Draft Data Quality Evaluation and Data Extraction Information for Environmental Release and
Occupational Exposure for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 20240 - Provides a
compilation of tables for the data extraction and data quality evaluation information for DCHP. Each
table shows the data point, set, or information element that was extracted and evaluated from a data
source that has information relevant for the evaluation of environmental release and occupational
exposure. This supplemental file may also be referred to as the "DCHP Data Quality Evaluation and
Data Extraction Information for Environmental Release and Occupational Exposure."
Draft Data Quality Evaluation Information for General Population, Consumer, and Environmental
Exposure for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 20241) - Provides a compilation of tables
for the data quality evaluation information for DCHP. Each table shows the data point, set, or
information element that was evaluated from a data source that has information relevant for the
evaluation of general population, consumer, and environmental exposure. This supplemental file
may also be referred to as the "DCHP Data Quality Evaluation Information for General Population,
Consumer, and Environmental Exposure."
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5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
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Draft Data Extraction Information for General Population, Consumer, and Environmental Exposure
for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024g) - Provides a compilation of tables for the
data extraction for DCHP. Each table shows the data point, set, or information element that was
extracted from a data source that has information relevant for the evaluation of general population,
consumer, and environmental exposure. This supplemental file may also be referred to as the
"DCHP Data Extraction Information for General Population, Consumer, and Environmental
Exposure."
Draft Data Quality Evaluation Information for Raman Health Hazard Epidemiology for
Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024n) - Provides a compilation of tables for the data
quality evaluation information for DCHP. Each table shows the data point, set, or information
element that was evaluated from a data source that has information relevant for the evaluation of
epidemiological information. This supplemental file may also be referred to as the "DCHP Data
Quality Evaluation Information for Human Health Hazard Epidemiology."
Draft Data Quality Evaluation Information for Human Health Hazard Animal Toxicology for
Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024m) - Provides a compilation of tables for the data
quality evaluation information for DCHP. Each table shows the data point, set, or information
element that was evaluated from a data source that has information relevant for the evaluation of
human health hazard animal toxicity information. This supplemental file may also be referred to as
the "DCHP Data Quality Evaluation Information for Human Health Hazard Animal Toxicology."
Draft Data Quality Evaluation Information for Environmental Hazardfor Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024k) - Provides a compilation of tables for the data quality evaluation
information for DCHP. Each table shows the data point, set, or information element that was
evaluated from a data source that has information relevant for the evaluation of environmental
hazard toxicity information. This supplemental file may also be referred to as the "DCHP Data
Quality Evaluation Information for Environmental Hazard."
Draft Data Extraction Information for Environmental Hazard and Human Health Hazard Animal
Toxicology and Epidemiology for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024f) - Provides a
compilation of tables for the data extraction for DCHP. Each table shows the data point, set, or
information element that was extracted from a data source that has information relevant for the
evaluation of environmental hazard and human health hazard animal toxicology and epidemiology
information. This supplemental file may also be referred to as the "DCHP Data Extraction
Information for Environmental Hazard and Human Health Hazard Animal Toxicology and
Epidemiology."
Associated Technical Support Documents (TSDs) - Provide additional details and information on
exposure, hazard, and risk assessments.
Draft Physical Chemistry and Fate and Transport Assessment for Dicyclohexyl Phthalate (DCHP)
(DCHP) (U.S. EPA. 2024z).
Draft Environmental Release and Occupational Exposure Assessment for Dicyclohexyl Phthalate
(DCHP) (U.S. EPA. 2024a).
Draft Consumer and Indoor Dust Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S.
EPA. 2024c).
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5322
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5324
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5327
5328
5329
5330
5331
5332
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5339
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Draft Environmental Media and General Population and Environmental Exposure Assessment for
DicyclohexylPhthalate (DCHP) (U.S. EPA. 2024p).
Draft Environmental Hazard Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024o).
Draft Non-Cancer Human Health Hazard Assessment for Dicyclohexyl Phthalate (DCHP) (U.S.
EPA. 2024V).
Draft Cancer Human Health Hazard Assessment for Di(l-ethylhexyl) Phthalate (DEHP), Dibutyl
Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl Phthalate (DIBP), and Dicyclohexyl
Phthalate (DCHP) (U.S. EPA. 2024b).
Draft Consumer Risk Calculator for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024e).
Draft Consumer Exposure Analysis for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024cT).
Draft Risk Calculator for Occupational Exposures for Dicyclohexyl Phthalate (DCHP) (U.S. EPA.
2024ab).
Draft Fish Ingestion Risk Calculator for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024r).
Draft Surface Water Human Exposure Risk Calculator for Dicyclohexyl Phthalate (DCHP) for P50
Flow Rates (U.S. EPA. 2024acT).
Draft Surface Water Human Exposure Risk Calculator for Dicyclohexyl Phthalate (DCHP) for P75
Flow Rates (U.S. EPA. 2024ae).
Draft Surface Water Human Exposure Risk Calculator for Dicyclohexyl Phthalate (DCHP) for P90
Flow Rates (U.S. EPA. 2024af).
Draft Ambient Air Exposure Assessment for Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024a).
Draft Occupational and Consumer Cumulative Risk Calculator for Dicyclohexyl Phthalate (DCHP)
(U.S. EPA. 2024v).
DraftMeta-Analysis and Benchmark Dose Modeling of Fetal Testicular Testosterone for Di(2-
ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl
Phthalate (DIBP), and Dicyclohexyl Phthalate (DCHP) (U.S. EPA. 2024s).
Draft Technical Support Document for the Cumulative Risk Analysis of Di(2-ethylhexyl) Phthalate
(DEHP), Dibutyl Phthalate (DBP), Butyl Benzyl Phthalate (BBP), Diisobutyl Phthalate (DIBP),
Dicyclohexyl Phthalate (DCHP), and Diisononyl Phthalate (DINP) Under the Toxic Substances
Control Act (TSCA) (U.S. EPA. 2024ah).
Draft Summary of Facility Release Data for Di(2-ethylhexyl) Phthalate (DEHP), Dibutyl Phthalate
(DBP), and Butyl Benzyl Phthalate (BBP) (U.S. EPA. 2024ac).
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Appendix D UPDATES TO THE DCHP CONDITIONS OF USE
TABLE
After the final scope document (U.S. EPA. 2020bI EPA received updated submissions under the 2020
CDR reported data. In addition to new submissions received under the 2020 CDR, the reporting name
codes changed for the 2020 CDR reporting cycle. Therefore, the Agency is amending the description of
certain DCHP COUs based on those new submissions and new reporting name codes. Also, EPA
received information from stakeholders on specific uses of DCHP. TableApx D-l summarizes the
changes to the COUs based on the new reporting codes in the 2020 CDR and any other new information
since the publication of the final scope.
Table Apx D-l. Additions and Name Changes to Categories and Subcategories of Conditions of
Use Based on CE
>R Reporting and Stakeholder Engagement
Life Cycle
Stage and
Category
Original Subcategory in
the Final Scope
Document
Occurred Change
Revised Subcategory in the
2024 Draft Risk Evaluation
Processing,
Processing as a
reactant
Processing aids not
otherwise listed in:
- Miscellaneous
manufacturing
Consolidated into a category and
associated subcategory under
"processing, incorporation into
formulation, mixture, or reaction
product, stabilizing agent" based
on further consultations with the
submitters of the CDR data, review
of their 2020 CDR cycle
submissions, and given EPA's
refined understanding of how
DCHP is used (U.S. EPA. 2024ai.
2020a).
Processing - Incorporation in
formulation, mixture, or reaction
product - Stabilizing agent
(plastics product manufacturing)
Processing,
Processing as a
reactant
Process regulator in:
- Paint and coating
manufacturing
- Plastic material and
resin manufacturing
- Plastics product
manufacturing
- Rubber product
manufacturing
Consolidated category and
associated subcategories under
"processing, incorporation into
formulation, mixture, or reaction
products" based on further
consultations with the submitters of
the CDR data, review of their 2020
CDR cycle submissions, and given
EPA's refined understanding of
how DCHP is used (U.S. EPA.
2024ai. 2020a).
Processing - Incorporation in
formulation, mixture, or reaction
product - Plasticizer (plastic
material and resin manufacturing;
rubber product manufacturing)
And
Processing - Incorporation in
formulation, mixture, or reaction
product - Stabilizing agent (paint
and coating manufacturing;
plastics product manufacturing)
Processing,
Incorporation into
formulation,
mixture, or
reaction product
Filler in:
- Rubber product
manufacturing
Removed COU based on further
consultations with the submitters of
the CDR data and review of their
2020 CDR cycle submissions (U.S.
EPA. 2024ai. 2020a). DCHP is not
used as a hardener, or the
previously reported CDR code of
"filler" (Nourvon Chemicals LLC.
2024).
N/A
Processing,
Incorporation into
formulation.
Laboratory chemical
Consolidated category and
associated subcategory under
"repackaging" as an example based
Processing - Repackaging -
Repackaging (e.g., laboratory
chemical)
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Life Cycle
Stage and
Category
Original Subcategory in
the Final Scope
Document
Occurred Change
Revised Subcategory in the
2024 Draft Risk Evaluation
mixture, or
reaction product
on further review of the COUs.
DCHP is not being reformulated or
used in laboratory manufacturing,
rather it is being used as a technical
standard or reference reagent (U.S.
EPA. 2020d).
Processing,
Incorporation into
formulation,
mixture, or
reaction product
Paint additives and
coating additives not
described by other codes:
- Printing ink
manufacturing
Consolidated category and
associated subcategory under a
COU that was reported in a more
recent CDR cycle.
Processing - Incorporation in
formulation, mixture, or reaction
product - Plasticizer (printing ink
manufacturing)
Processing,
Incorporation into
formulation,
mixture, or
reaction product
N/A
Updated the subcategory to reflect
the 2020 CDR cycle.
Processing - Incorporation in
formulation, mixture, or reaction
product - Plasticizer (plastic
material and resin
manufacturing)
Processing,
Incorporation into
formulation,
mixture, or
reaction product
Processing aids not
otherwise listed:
- Services
- Paint and coating
manufacturing
- Asphalt paving, roofing,
and coating materials
manufacturing
- Adhesive
manufacturing
Consolidated category and
associated subcategories as a
"stabilizing agent" based on further
consultations with the submitters of
the CDR data and review of their
2020 CDR cycle submissions (U.S.
EPA. 2024ai: Nourvon Chemicals
LLC. 2020; U.S. EPA. 2020a.
2019c).
Processing - Incorporation in
formulation, mixture, or reaction
product - Stabilizing agent
(adhesive manufacturing; asphalt
paving, roofing, and coating
materials manufacturing; paint
and coating manufacturing)
Processing,
Incorporation into
formulation,
mixture, or
reaction product
Process regulator in:
- Adhesive
manufacturing
Consolidated category and
associated subcategory under a
COU that was both reported in a
more recent CDR cycle and more
appropriate given EPA's
understanding of how DCHP is
used.
Processing - Incorporation in
formulation, mixture, or reaction
product - Stabilizing agent
(adhesive manufacturing)
Processing;
Incorporation into
formulation,
mixture, or
reaction product
N/A
Updated the subcategory to reflect
the 2020 CDR cycle.
Processing - Incorporation in
formulation, mixture, or reaction
product - Stabilizing agent
(paints and coating
manufacturing)
Processing,
Incorporation into
formulation,
mixture, or
reaction product
N/A
Updated the subcategory to reflect
the 2020 CDR cycle.
Processing - Incorporation in
formulation, mixture, or reaction
product - Stabilizing agent
(plastics product manufacturing)
Industrial Use,
Adhesives and
sealants
Adhesives and sealants
in:
- Transportation
equipment manufacturing
- Computer and
electronic product
manufacturing
Updated the category and
subcategory to add "computer and
electronic product manufacturing"
and "transportation equipment
manufacturing" as examples to not
preclude other industrial sectors.
Industrial Use - Adhesives and
sealants (e.g., computer and
electronic product
manufacturing; transportation
equipment manufacturing)
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Life Cycle
Stage and
Category
Original Subcategory in
the Final Scope
Document
Occurred Change
Revised Subcategory in the
2024 Draft Risk Evaluation
Industrial Use
N/A
Added the COU "paints and
coatings" to the new life cycle
stage of "industrial use" based on a
new understanding of information
from an SDS that explained the use
could take place on an industrial
scale (Carbolinc. 2019b).
Industrial Use - Paints and
coatings
Industrial Use,
Plastic and rubber
products not
covered
elsewhere
Plastic and rubber
products not covered
elsewhere in:
- Transportation
equipment manufacturing
Updated the category and
subcategory to better reflect 2020
CDR reporting codes and to add
"transportation equipment
manufacturing" as an example to
not preclude other industrial
sectors.
Industrial Use - Other articles
with routine direct contact during
normal use including rubber
articles; plastic articles (hard)
(e.g., transportation equipment
manufacturing)
Commercial Use,
Plastic and rubber
products not
covered
elsewhere
Plastic and rubber
products not covered
elsewhere
Updated the category and
subcategory to reflect the 2020
CDR cycle.
Commercial Use - Other articles
with routine direct contact during
normal use including rubber
articles; plastic articles (hard)
Consumer Use,
Arts, crafts, and
hobby materials
Arts, crafts, and hobby
materials (e.g., modeling
clay)
Removed this COU upon further
review, concluding it was no
longer reasonably foreseen.
N/A
Consumer Use,
Plastic and rubber
products not
covered
elsewhere
Plastic and rubber
products not covered
elsewhere
Updated the category and
subcategory to reflect the 2020
CDR cycle.
Consumer Use - Other articles
with routine direct contact during
normal use including rubber
articles; plastic articles (hard)
As indicated in Table Apx D-l, the changes are based on close examination of the CDR reports,
including the 2020 CDR reports that were received after the scope was completed, additional research
on the COUs, additional comments from stakeholders, and overall systematic review of the use
information.
When developing this draft risk evaluation, EPA concluded that some subcategories of the COUs listed
in the final scope document (U.S. EPA. 2020b) were redundant and consolidation was needed to avoid
evaluation of the same COU multiple times. The Agency further concluded that there were some
instances where subcategory information on the processing and uses of DCHP was misreported by CDR
reporters based on outreach with stakeholders. For these instances, EPA recategorized the activity
described in the COU listed in the scope to fit the description of the COU included in this draft risk
evaluation.
In addition, EPA did further analysis of the following COUs, which resulted in the changes presented on
the table that warrant further explanation because these COUs were changed significantly between the
final scope and this draft risk evaluation:
• Processing, Processing as a reactant, "processing aids not otherwise listed in miscellaneous
manufacturing; process regulator in paint and coating manufacturing, plastic material and resin
manufacturing, plastics product manufacturing, and rubber product manufacturing" were all
removed from the COUs as it was determined (due in part to a refined understanding of how
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DCHP is used and stakeholder outreach) that DCHP is not used as a reactant and it is more
appropriately characterized as "Processing - incorporated into a formula, mixture or reaction
product." These uses are better captured under other processing COUs that more accurately
reflect EPA's understanding of how DCHP is used.
EPA has also included further information about any other COUs (reported in the 2020 CDR cycle (U.S.
EPA. 2020a) or otherwise) that are not included in the draft DCHP risk evaluation:
• Processing, Processing as a reactant, "plasticizer in plastics product manufacturing; intermediate
in all other basic organic chemical manufacturing; stabilizing agent in paint and coating
manufacturing and plastics product manufacturing; and processing aids not otherwise specified
in plastics product manufacturing" were reported in the 2020 CDR cycle and were not included
in the draft risk determination analysis as it was determined that DCHP is not used as a reactant
and it is more appropriately characterized as "Processing - incorporated into a formula, mixture
or reaction product." These uses are better captured under other processing COUs that more
accurately reflect EPA's understanding of how DCHP is used.
• Processing, Processing as a reactant, "hardener in paint and coating manufacturing; and plastics
product manufacturing" were reported in the 2020 CDR cycle and were not included in the draft
risk determination analysis as it was determined that DCHP is not used as a reactant and is more
appropriately characterized as "Processing - incorporated into a formula, mixture or reaction
product." Additionally, based on Agency research and communication with stakeholders it is
EPA's understanding that the use of "hardener" is better captured as a "stabilizing agent" for the
draft DCHP risk evaluation (U.S. EPA. 2024ai). Ultimately, these uses are better captured under
other processing COUs that more accurately reflect EPA's understanding of how DCHP is used.
• Processing, Processing incorporation into formulation, mixture, or reaction product, "processing
aids not otherwise specified in plastics product manufacturing" was reported in the 2020 CDR
cycle and was not included in the draft risk determination analysis after additional research and
communication with stakeholders (U.S. EPA. 2024ai). It is EPA's understanding that this COU
is more appropriately consolidated into Processing, Processing incorporation into formulation,
mixture, or reaction product, "stabilizing agent."
• Note that in the final scope document for DCHP (U.S. EPA. 2020b). EPA removed the consumer
use of dicyclohexyl phthalate in toys, playground, and sporting equipment as a COU for
numerous reasons, which include: a public comment received on the draft DCHP scoping
document (Vertellus LLC. 2020); the Consumer Product Safety Commission's (CPSC) Chronic
Hazard Advisory Panel (CHAP) report from 2014 (U.S. CPSC. 2014) that states, "DCHP is
currently not found in children's toys or child care articles, and it is not widely found in the
environment" (page 117); the preamble of the 2017 CPSC final rule titled "Prohibition of
Children's Toys and Child Care Articles Containing Specified Phthalates," which explains that".
. . the CPSC staff has not detected DCHP in toys and child care articles during routine
compliance testing thus far. . ." (U.S. CPSC. 2017); and CPSC's final rule, which prohibits
manufacture for sale, offer for sale, distribution in commerce, and importation into the United
States of any children's toy or child care article that contains more than 0.1 percent of
dicyclohexyl phthalate as it "would prevent [DCHP's] use as a substitute for other banned
phthalates" (82 FR 49982 (2017); 16 CFR 1307.3). As a result, EPA has no reasonably available
information demonstrating that the consumer use of dicyclohexyl phthalate in toys, playground,
and sporting equipment is intended, known, or reasonably foreseen, and therefore removed this
COU from the final scope and has not included it in the analysis for this draft risk evaluation of
DCHP.
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Appendix E CONDITIONS OF USE DESCRIPTIONS
The following descriptions are intended to include examples of uses, so as not to exclude other activities
that may also be included in the COUs of the chemical substance. To better describe the COU, EPA
considered CDR submissions from previous CDR cycles for DCHP (CASRN 84-61-7), and the COU
descriptions reflect what the Agency identified as the best fit for those submissions. Examples of
articles, products, or activities are included in the following descriptions to help describe the COU but
are not exhaustive. EPA uses the terms "articles" and "products" or product mixtures in the following
descriptions and is generally referring to articles and products as defined by 40 CFR part 751. There
may be instances where the terms are used interchangeably by a company or commenters, or by EPA in
reference to a code from CDR reports that are referenced (e.g., "plastics products manufacturing," or
"fabric, textile, and leather products"), EPA will clarify as needed when these references are included
throughout the COU descriptions below.
5.1 Manufacturing - Domestic Manufacturing
Domestic manufacture means to manufacture or produce DCHP within the United States. For purposes
of the DCHP risk evaluation, this includes the extraction of DCHP from a previously existing chemical
substance or complex combination of chemical substances and loading and repackaging (but not
transport) associated with the manufacturing or production of DCHP.
DCHP is typically manufactured in a closed system through catalytic esterification of phthalic anhydride
and cyclohexanol in solvent at elevated temperatures (130 °C) (U.S. CPSC. 2010). After the reaction,
excess alcohol is recovered and DCHP is purified through vacuum distillation or activated charcoal
(U.S. EPA. 2020b). Based on manufacturing operations for similar phthalates, activities may also
include filtrations and quality control sampling of the DCHP product. Additionally, manufacturing
operations include equipment cleaning/reconditioning and product transport to other areas of the
manufacturing facility or offsite shipment for downstream processing or use. Current manufacturing
processes can achieve a DCHP purity of 99 percent or greater, with some impurities of water and
phthalic acid (U.S. CPSC. 2010). This COU includes the typical manufacturing process and any other
similar production of DCHP.
Examples of CDR Submissions.
In the 2016 CDR cycle, one company reported domestic manufacturing of DCHP (CASRN 84-61-7) as
large crystal pellets.
In the 2020 CDR cycle, two companies reported domestic manufacturing of DCHP (CASRN 84-61-7).
One CDR company reported domestic manufacturing of DCHP as pellets or large crystals, while the
second company reported domestic manufacturing of DCHP as a dry powder.
E.2 Manufacturing - Importing
Import refers to the import of DCHP into the customs territory of the United States. In general,
chemicals may be imported into the United States in bulk via water, air, land, and intermodal shipments,
and loading and repackaging (but not transport) associated with the import of DCHP (Tomer and Kane.
2015). These shipments take the form of oceangoing chemical tankers, railcars, tank trucks, and
intermodal tank containers (U.S. EPA. 2020b).
Imported DCHP is shipped in either dry powder, liquid, water or solvent wet solid form (U.S. EPA.
2020a). Import sites unload the import containers and transfer DCHP into smaller containers (bags or
supersacks) for downstream processing, use within the facility, or offsite use. Operations may include
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quality control sampling of DCHP product and equipment cleaning. No changes to chemical
composition occur during importation of this COU (U.S. EPA. 2022a).
Examples of CDR Submissions.
In the 2016 CDR cycle, one company reported importation of DCHP (CASRN 84-61-7) in a solid form.
In the 2020 CDR cycle, two companies reported importation of DCHP (CASRN 84-61-7).
One CDR company reported importation of DCHP as dry powder, liquid, while the second company
reported importation of DCHP as water or a solvent wet solid.
E.3 Processing - Incorporation into Formulation, Mixture, or Reaction
Product - Adhesive and Sealant Chemicals in Adhesive
Manufacturing
This COU refers to the preparation of a product; that is, the incorporation of DCHP into formulation,
mixture, or a reaction product that occurs when a chemical substance is added to a product (or product
mixture), after its manufacture, for distribution in commerce. In this case, processing of DCHP into an
adhesive and sealant in adhesive manufacturing.
Based on the 2009 Emission Scenario Document (ESD) on the Manufacture of Adhesives, a typical
adhesive incorporation site receives and unloads DCHP into adhesive and sealant formulations in
industrial mixing vessels as a batch blending or mixing process, with no reactions or chemical changes
occurring to the plasticizer (i.e., DCHP) during the mixing process (OECD. 2009a). Process operations
may also include quality control sampling. EPA expects that sites will load DCHP-containing adhesive
and sealant products into bottles, small containers, or drums depending on the product type. (OECD.
2009a).
Examples of CDR Submissions.
In the 2016 cycle, one company reported the use of DCHP (CASRN 84-61-7) as adhesive and sealant
chemicals in adhesive manufacturing.
E.4 Processing - Incorporation into Formulation, Mixture, or Reaction
Product - Plasticizer (Adhesive Manufacturing; Paint and Coating
Manufacturing; Plastic Material and Resin Manufacturing; Plastics
Product Manufacturing; Printing Ink Manufacturing; and Rubber
Product Manufacturing)
This COU refers to the preparation of a product; that is, the incorporation of DCHP into formulation,
mixture, or a reaction product that occurs when a chemical substance is added to a product (or product
mixture) after its manufacture, for distribution in commerce—in this case as a plasticizer in various
industrial sectors and uses, specifically as an adhesive, paint and coating, plastic material and resin,
plastic product, printing or PVC plastisol ink and as a rubber product.
The American Coatings Association explained that DCHP is a plasticizer, additive and impurity in
adhesives in amounts less than 1 percent (AC A. 2019) and according to information provided to EPA,
DCHP is also used within products or formulations for the manufacture, operation and maintenance of
aerospace products (AIA. 2019). More specifically, the Aerospace Industries Association explained that
DCHP can be used as a plasticizer for nitrocellulose, chlorinated rubber polyvinyl chloride and other
polymers and adhesives.
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In manufacturing of plastic material and resin through non-PVC and PVC compounding, DCHP is
blended into polymers. Compounding involves the mixing of the polymer with the plasticizer and other
chemical such as fillers and heat stabilizers. The plasticizer needs to be absorbed into the particle to
impart flexibility to the polymer. For PVC compounding, compounding occurs through mixing of
ingredients to produce a powder (dry blending) or a liquid (plastisol blending). The most common
process for dry blending involves heating the ingredients in a high intensity mixer and transfer to a cold
mixer. The plastisol blending is done at ambient temperature using specific mixers that allow for the
breakdown of the PVC agglomerates and the absorption of the plasticizer into the resin particle. EPA is
also aware that DCHP may be incorporated into PVC plastisol inks and inks for screen printing
(Hallstar. 2022; LANXESS. 2021; Gans Ink and Supply. 2018; U.S. CPSC. 2015).
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
plastics product manufacturing and one CDR company reported the use of DCHP as a plasticizer in
printing ink manufacturing.
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
plastics material and resin manufacturing and one CDR company reported the use of DCHP as a
plasticizer in adhesive manufacturing.
E.5 Processing - Incorporation into Formulation, Mixture, or Reaction
Product - Stabilizing Agent (Adhesive Manufacturing; Asphalt
Paving, Roofing, and Coating Materials Manufacturing; Paints and
Coating Manufacturing; and Plastics Product Manufacturing)
This COU refers to the preparation of a product; that is, the incorporation of DCHP into formulation,
mixture, or a reaction product that occurs when a chemical substance is added to a product (or product
mixture), after its manufacture, for distribution in commerce. In this case DCHP is used as a stabilizing
agent, specifically as a phlegmatizer (a compound that minimizes the explosive tendency of another
compound or material) for dibenzoyl peroxide (BPO) and peroxide-based formulations to improve the
safety and handling properties and to prevent explosions (U.S. EPA. 2024ai; AIA. 2019). These BPO
mixtures (in which DCHP is present) are then used as a curing agent for unsaturated polyesters or
methyl methacrylate (MMA) systems, which is used in various industrial sectors and uses including
asphalt, roofing, and flooring systems, coatings, adhesives, and within the aerospace industry (U.S.
EPA. 2024ai; Nouryon Chemicals LLC. 2020; AIA. 2019; U.S. EPA. 2019c). EPA has confirmed that
this COU has recently been discontinued with the CDR submitter. However, the use of DCHP as a
stabilizing agent was only recently ceased (i.e., in 2021) and the available information regarding DCHP
suggests that this COU could occur. Therefore, it is included in EPA's evaluation.
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a process
regulator in paints and coating manufacturing, which has been recategorized in the COU table to
"stabilizing agent" after discussions with the company that purchased the previous 2016 reporting
company (U.S. EPA. 2024ai. 2019c). See Appendix D for more information on the changes from the
COU from the Final Scope of the Risk Evaluation for Dicyclohexyl Phthalate (DCHP); CASRN 84-61-7
(U.S. EPA. 2020b).
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a stabilizing agent
in paints and coating manufacturing.
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E.6 Processing - Incorporation into Articles - Plasticizer (Plastics Product
Manufacturing and Rubber Product Manufacturing)
This COU refers to the preparation of an article; that is, the incorporation of DCHP into articles,
meaning DCHP becomes an integral component of the article, after its manufacture, for distribution in
commerce. In this case, DCHP is present in a raw material such as rubber or plastic that contains a
mixture of plasticizers and other additives, and this COU refers to the manufacturing of PVC and non-
PVC articles including rubber, plastic, and miscellaneous articles using those raw materials. According
to information provided to EPA, DCHP is used as a plasticizer in plastic and rubber articles used in the
aerospace industry (AIA. 20191 and a variety of articles in transportation equipment such as automotive
vehicles (MEMA. 2019). Simple and complex plastic and rubber articles containing DCHP are also
assumed to be used in electronics (U.S. CPSC. 20151 as well as a variety of other industrial and
commercial end uses. DCHP is also assumed to be used as a plasticizer in a variety of other simple and
complex articles such those found in building and construction materials (LANXESS. 2021).
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
plastics products manufacturing, one company reported the commercial and consumer use of DCHP in
plastic and rubber products not covered elsewhere.
In the 2020 CDR cycle, one company reported the commercial and consumer use of DCHP (CASRN
84-61-7) as a plasticizer in other articles with routine direct contact during normal use including rubber
articles; plastic articles (hard), which is a further refined description compared with the 2016 CDR cycle
code of "plastic and rubber products not covered elsewhere."
E.7 Processing - Repackaging (e.gLaboratory Chemical)
Repackaging refers to the preparation of DCHP for distribution in commerce in a different form, state,
or quantity than originally received or stored by various industrial sectors, including chemical product
and preparation manufacturing, wholesale and retail trade, and laboratory chemicals manufacturing. This
COU includes the transferring of DCHP from a bulk container into smaller containers. One company
explained that DCHP and phthalates more generally are domestically repackaged for laboratory use
(U.S. EPA. 2020d). This COU would not apply to the relabeling or redistribution of a chemical
substance without removing the chemical substance from the original container it was supplied in. No
changes to chemical composition occur during repackaging of this COU (U.S. EPA. 2022a).
This COU was not reported in the 2016 or 2020 CDR cycles.
E.8 Processing - Recycling
This COU refers to the process of treating generated waste streams (i.e., which would otherwise be
disposed of as waste) containing DCHP that are collected, either on-site or at a third-party site, for
commercial purpose. DCHP is primarily recycled industrially in the form of DCHP-containing
PVC/plastic waste streams. New PVC can be manufactured from recycled and virgin materials at the
same facility. Some (ENF Plastic. 2024) estimate a total of 228 plastics recyclers operating in the United
States of which 58 accept PVC wastes for recycling. It is unclear if the total number of sites includes
some or all circular recycling sites—facilities where new PVC can be manufactured from recycled and
virgin materials on the same site. Articles containing DCHP from inks, coatings, etc., may also be
recycled (U.S. EPA. 2020b). EPA notes that although DCHP was not reported for recycling in the 2016
or 2020 CDR reporting periods, EPA is assuming that recycling waste streams could contain DCHP.
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E.9 Distribution in Commerce
For purposes of assessment in this draft risk evaluation, distribution in commerce consists of the
transportation associated with the moving of DCHP or DCHP-containing products between sites
manufacturing, processing or recycling DCHP or DCHP-containing products, or to final use sites, or for
final disposal of DCHP or DCHP-containing products. More broadly under TSCA, "distribution in
commerce" and "distribute in commerce" are defined under TSCA section 3(5). No changes to chemical
composition occur during transportation of DCHP (U.S. EPA. 2022a).
E.10 Industrial Use - Adhesive and Sealants (e.gComputer and Electronic
Product Manufacturing; Transportation Equipment Manufacturing)
This COU refers to DCHP as it is used in various industrial sectors as a component of adhesive or
sealant mixtures. Meaning the use of DCHP after it has already been incorporated into an adhesive
and/or sealant product or mixture, as opposed to when it is used upstream (e.g., when DCHP is
processed into the adhesive and sealant formulation). The American Coatings Association explained that
DCHP is a plasticizer, additive, and impurity in adhesives in amounts less than 1 percent (ACA. 2019).
According to information provided to EPA, DCHP is used as an adhesive within the aerospace industry
(AIA. 2019) and as an adhesive sealant for body panel assemblies and parts by automobile
manufacturers applications (MEM A. 2019). EPA has also identified several examples of specific
products for this COU, such as a nonconductive die attach adhesive containing DCHP at concentrations
of 0.1 to 1 percent. This adhesive has been formulated for use in high throughput die attach applications
within the semi-conductor industry within various types of electronics (e.g., automotive cameras)
(Henkel. 2024. 2019. 2017).
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as adhesive and
sealant chemicals in adhesive manufacturing.
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
adhesive manufacturing.
E.ll Industrial Use - Finishing Agent - Cellulose Film Production
This COU refers to the use of DCHP as a component of the finishing agent used in cellulose film
production. Meaning the use of DCHP after it has already been incorporated into the finishing agent
itself, as opposed to when it is used upstream (e.g., when DCHP is processed into the finishing agent or
paint and coating formulation).
CDR described a "finishing agent" as a chemical substance used to impart such functions as softening,
static-proofing, wrinkle resistance, and water repellence. Substances may be applied to textiles, paper,
and leather. In this case DCHP is used during the cellulose film production to bathe or coat the film,
giving it barrier properties as well as promoting heat seal. This cellulose film is then used in a variety of
labeling, and packaging end uses (U.S. EPA. 2020c; Earthiustice. 2019).
This COU was not reported in the 2016 or 2020 CDR reporting cycles.
E.12 Industrial Use - Inks, Toner, and Colorant Products
This COU refers to the use of DCHP in various industrial sectors as a component in ink, toner, and
colorant products. Meaning the use of DCHP after it has already been incorporated into ink, toner,
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and/or colorant products, or while it is being applied to various articles, as opposed to when it is used
upstream (e.g., when DCHP is processed into the ink, toner, and colorant product formulation).
According to information provided to EPA in 2021, DCHP (referred to in this case as Uniplex 250) has
been used as an element of PVC inks/PVC plastisol formulations (Hallstar. 2022; LANXESS. 2021;
U.S. EPA. 2021c. 2019e). Uniplex 250 is also marketed as being used as a polymer additive in labels
and printing ink formulations (Hallstar. 2022) and DCHP has been used as part of the screen-printing
process for textiles (Gans Ink and Supply. 2018). Printing inks are composed of colorants (e.g.,
pigments, dyes and toners) dispersed in a formulation to form a paste, liquid or solid, which can be
applied to a substrate surface and dried (U.S. EPA. 2010). Screen printing requires a mesh screen to
transfer the ink to a substrate, whereas digital printing allows for the transfer of a digital image directly
onto a substrate. Inkjet printing is the most common form of digital printing. It involves the application
of small drops of ink onto a substrate, with direct contact between the ink nozzle and the substrate (U.S.
EPA. 2010).
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
printing ink manufacturing.
E.13 Industrial Use - Paints and Coatings
This COU refers to the use of DCHP in various industrial sectors as a component in paints and coating
mixtures. This is a use of DCHP after it has already been incorporated into paint and coating or BPO
mixtures, or while it is being applied to various articles, as opposed to when it is used upstream (e.g.,
when DCHP is processed into adhesive, sealant or BPO formulation).
EPA has identified an example of an industrial paint and coating product for this COU; a single-
component silicone acrylic finish that air dries and is suitable for high temperature exposures up to
500 °F with DCHP concentrations of 2.5 to less than 10 percent. This paint and coating is applied via
pressurized or conventional spray and can be used to protect various elements, equipment, etc. in an
industrial or manufacturing setting (Carboline. 2019a. b; U.S. EPA. 2019d).
EPA expects that products under this COU would be applied in the industrial sector; however, note that
it is possible for these products to be purchased by commercial users and applied in the commercial
sector as well.
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a process
regulator in paints and coating manufacturing, which has been recategorized in the COU table to
"stabilizing agent" after discussions with the company that purchased the previous 2016 reporting
company (U.S. EPA. 2024ai). See Appendix D for more information on the changes from the COUs
from the Final Scope of the Risk Evaluation for Dicyclohexyl Phthalate (DCHP) CASRN 84-61-7 (U.S.
EPA. 2020bY
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a stabilizing agent
in paints and coating manufacturing.
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E.14 Industrial Use - Other Articles with Routine Direct Contact During
Normal Use Including Rubber Articles; Plastic Articles (Hard) (e.g
Transportation Equipment Manufacturing)
This COU refers to the use of DCHP in rubber and plastic products in various industrial sectors, such as
transportation equipment manufacturing. Meaning the use of DCHP after it has already been
incorporated into a plastic or rubber product, as opposed to when it is used upstream (e.g., when DCHP
is processed into the plastic/rubber product).
According to information provided to EPA, DCHP is used as a plasticizer in plastic and rubber products
used in the aerospace industry (AIA. 2019) and a variety of transportation equipment such as both
vehicles production parts and replacement parts (MEM A. 2019). The Alliance of Automobile
Manufacturers and the Motor & Equipment Manufacturers Association did explain that "[t]he average
scope of the relative mass of DCHP in the parts from the Alliance's data collection is 0.24 gram.
Excluding body/exterior parts, that average drops below 0.01 gram" (MEMA. 2019).
As such, workers would be expected to handle or touch products covered by this COU with their hands
and be exposed to DCHP through dermal contact.
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the commercial use of DCHP (CASRN 84-61-7) in
plastic and rubber products not covered elsewhere.
In the 2020 CDR cycle, the same company reported the commercial use of DCHP (CASRN 84-61-7) as
a plasticizer in other articles with routine direct contact during normal use including rubber articles;
plastic articles (hard), which is a further refined description compared to the 2016 CDR cycle code of
"plastic and rubber products not covered elsewhere".
E.15 Commercial Use - Adhesives and Sealants
This COU is referring to the commercial use of DCHP in adhesives and sealants. Meaning the use of
DCHP-containing adhesives and sealants in a commercial setting, such as a business or at a job site, as
opposed to upstream use of DCHP (e.g., when DCHP is processed into the adhesive and sealant
formulation) or use in an industrial setting.
Workers in a commercial setting generally apply adhesives and sealants that already have DCHP
incorporated as a plasticizer or combine two-part adhesives where DCHP acts as a phlegmatizer with
BPO in unsaturated polyesters or MMA systems (U.S. EPA. 2024ai). The American Coatings
Association explained that DCHP is a plasticizer, additive and impurity in adhesives in amounts less
than one percent (ACA. 2019). According to information provided to EPA, DCHP is used as an
adhesive within the aerospace industry (AIA. 2019). and an adhesive sealant for body panel assemblies
and parts by automobile manufacturers applications (MEMA. 2019).
Commercial adhesives and sealants that are used to fasten other materials together or to prevent the
passage of liquid or gas are captured under this COU. For example, products under this COU can be
two-part adhesives, glues or caulks, which are stored in separate parts, generally a base and an activator
or a resin and a hardener that may undergo a reaction or cure once combined. EPA expects that some
commercial applications of adhesives and sealants containing DCHP may occur using non-pressurized
methods, but that most commonly, the products containing DCHP are more likely applied via a syringe
or caulk gun. More specifically, EPA has identified several examples of products for this COU, such as
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a metal bonding adhesive used in variety of automotive care applications (e.g., panel bonding, weld and
rivet bonding of quarter panels, rear body panels, roof panels, door skins, van side panels and outer truck
bed panels) that contain DCHP concentrations of one to five percent (Lord Corporation. 2021. 2020.
2017) as well as a similar metal bonding product with DCHP concentrations from three to less than five
percent (Ford Motor Company. 2015). EPA also identified various two-part adhesive anchoring systems,
such as a two-part hammer-capsule system designed for use in the installation of a threaded rod into
solid concrete and masonry materials that contained DCHP concentrations of 1 to 2.5 percent (DeWalt.
2024b. 2022. 2020). as well as another two-part polyester liquid system to be used once again in
construction and building environments (MKT. 2023a. b, 2018).
EPA expects that the use of these types of products would occur in commercial applications; however,
EPA notes that these products are likely to be sourced by DIY consumers through various online
vendors as well (DeWalt. 2024a; Lord Corporation. 2024; MKT. 2024).
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as adhesive and
sealant chemicals in adhesive manufacturing.
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
adhesive manufacturing.
E.16 Commercial Use - Building/Construction Materials Not Covered
Elsewhere
This COU is referring to the commercial use of DCHP in building/construction materials not covered
elsewhere. Meaning the use of DCHP-containing building/construction materials in a commercial
setting, such as at a business or at a job site, as opposed to upstream use of DCHP (e.g., when DCHP is
processed into articles).
According to information provided to EPA in 2021, DCHP (referred to in this case as Uniplex 250) has
been used as an article in a "range of construction products-boards" (LANXESS. 2021). These boards
are presumed to be used in a variety of commercial applications and settings.
Examples of CDR Submissions
In the 2012 CDR cycle, one company reported the commercial use of DCHP (CASRN 84-61-7) as
building/construction materials not covered elsewhere.
E.17 Commercial Use - Ink, Toner, and Colorant Products
This COU refers to the commercial use of DCHP in ink, toner, and colorant products. Meaning the use
of DCHP-containing ink, toner, and/or colorant products in a commercial setting, such as a business or
at a job site, as opposed to upstream use of DCHP (e.g., when DCHP is processed into the ink, toner,
and colorant product formulation) or use in an industrial setting.
According to information provided to EPA in 2021, DCHP (referred to in this case as Uniplex 250) has
been used as an element of PVC inks/PVC plastisol formulations (LANXESS. 2021; U.S. EPA. 2021c.
2019e). Uniplex 250 is also marketed as being used as a polymer additive in labels and printing ink
formulations (Hall star. 2022) and has been used as part of the screen-printing process for textiles (Gans
Ink and Supply. 2018). The expected users of these products would be specific to the printing
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community and these inks would likely be applied through mechanical methods or as part of the screen-
printing process.
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
printing ink manufacturing.
E.18 Commercial Use - Laboratory Chemicals
This COU is referring to the commercial use of DCHP in laboratory chemicals. DCHP can be used as a
laboratory chemical, such as a chemical standard or reference material during analyses. Some laboratory
chemical manufacturers identify use of DCHP as a certified reference material and research chemical
(Restek Corporation. 2024; Sigma-Aldrich. 2024a. b; U.S. EPA. 2020d; SPEX CertiPrep. 2019). Users
of the products under this category would be expected to apply these products through general
laboratory use applications. According to information provided to EPA by NASA, the Agency indicated
that DCHP is used as a laboratory chemical in applications such as analytical standards, research,
equipment calibration and sample preparation (NASA. 2020).
DCHP has also been used as the powder in a two-part laboratory acrylic mounting system for laboratory
specimens that are sensitive to high pressures and temperatures, as well as an embedding polymer resin
kit intended for preparation for samples for high resolution light microscopy (Ted Pella. 2024. 2017).
DCHP in this case is used as part of a BPO catalyst.
This use was not reported to EPA in the 2016 or 2020 CDR cycles.
E.19 Commercial Use - Paints and Coatings
This COU is referring to the commercial use of DCHP as a plasticizer and stabilizer (i.e., phlegmatizer)
in paints and coating systems. Meaning the use of DCHP-containing paints and coatings in a commercial
setting, such as at a business or at a job site, as opposed to upstream use of DCHP (e.g., when DCHP is
processed into the paint, coating, or BPO formulation) or use in an industrial setting.
Workers in a commercial setting generally apply paints and coatings that already have DCHP
incorporated as a plasticizer or combine two (or even sometimes three) part paints and coatings where
DCHP acts as a phlegmatizer with BPO in unsaturated polyesters or MMA systems (U.S. EPA. 2024ai).
The solid DCHP/BPO product often acts as a catalyst or curing agent when mixed with a second, often
liquid, component by workers at the end use site before application. This mixing begins the
polymerization reaction or process. Workers are expected to be potentially exposed when mixing
components to form a liquid paint/coating, when transferring the liquid mixture to the application
equipment if necessary, and/or when applying the coating or system itself to the substrate (U.S. EPA.
2014b; OECD. 2009b; U.S. EPA. 2004d). End use sites may also receive liquid paint and coating
formulations already containing DCHP as a single component, making the need to mix two components
obsolete. Application methods for DCHP-containing paints and coatings may include spray, brush,
and/or trowel coating.
Various paints and coatings that utilize DCHP are applied in commercial settings such as in roofing,
construction, and in cement/protection for high traffic areas, etc. often to provide waterproofing, UV
protection and/or chemical resistance. More specifically, EPA has identified several examples of
products for this COU, such as a single-component silicone acrylic finish that air dries and is suitable for
high temperature exposures up to 500 °F with DCHP concentrations of 2.5 to less than 10 percent. This
paint and coating is applied via pressurized spray and can be used to protect various elements,
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equipment, and so on, in an industrial or manufacturing setting (Carboline. 2019a. b; U.S. EPA. 2019d).
EPA also identified various two or even multi-part paints and coatings systems including: a vinyl ester
silicone filled mortar; a three component, MMA-based grout; a poly methyl-methacrylate (PMMA) resin
used in roofing and waterproofing applications; a polyurethane modified methyl methacrylate
(PUMMA) vehicular and pedestrian traffic coating system; and a MMA resin used as a penetrating
crack healer/sealer or to fortify extremely porous concrete substrates.
The vinyl ester silicone filled mortar contained concentrations of DCHP at less than 0.005 percent and
when used with chemical-resistant masonry units and the proper membrane, it will protect concrete and
steel substrates from chemical attack and physical abuse. The mortar is a two-part system including a
liquid and the powder (which contains DCHP), which must be mixed together (3.25 parts powder to 1
part liquid) prior to trowel based application of an average one-eighth inch thick bed directly on top of
membrane or preceding course of brickwork. According to the company, this product is used in the
construction of floors, sumps, trenches, tanks, vessels and bleach towers in chemical processing; food
and beverage plants; dairies; laboratories; and textile, steel and pulp and paper mills (Sauereisen. 2024.
2022).
The three component MMA based grout is flowable, non-shrink, durable polymer grout that according
to the company's website, can be used as the grouting of bearing plates on bridges and trestles,
rehabilitation of bridge decks, airport runways, expansion joints and column grouting. DCHP can be
found in the catalyst or Part B in concentrations of 50 to 51 percent. Seven to 14 fluid ounces (oz)
(depending on the ambient air temperature) of the catalyst/Part B, is mixed with 1 gallon of Part A resin,
and 70 lb of Part C grout aggregate. Once mixed, the company directs workers to distribute the blended
resin over the surface and brush in or prepare a form and pour the material into place (ChemMasters.
2024. 2018. 2017a. b).
The PMMA resin is used in roofing and waterproofing applications through a two-part plus
fleece/membrane self-flashing and self-adhering system, which according to the company is used in
structural below-grade concrete surfaces, and protected roof and split-slab decks (CETCO. 2024. 2018a.
b, c). DCHP has been identified in the catalyst powder at 50 percent which is then mixed with the resin
at various ratios ranging from 2 to 6 percent depending on the weight of the resin used and temperature.
The polyurethane modified methyl methacrylate (PUMMA) vehicular and pedestrian traffic coating
system, is specifically designed for use in parking structures, balconies, stadium seating, walkways,
plaza decks, etc. (Hydro-Gard. 2012a. b). This is a multi-component system, which uses a catalyst that
contains DCHP in concentrations of 40 to 55 percent combined with a resin and a flashing or polyester
fleece to create a liquid applied waterproofing membrane/coating (Hydro-Gard. 2024. 2017a. b).
Finally, the last product example for commercial paints and coatings is an MMA resin that is used as a
penetrating crack healer/sealer or to fortify extremely porous concrete substrates, such as parking and
bridge decks, loading docks and warehouses. DCHP can be found in the initiator component in
concentrations of 50 to less than 100 percent. To begin the hardening process the workers must add
roughly 0.5 oz to a gallon of resin at around 32 to 39 degrees, increasing up to 2 oz at 90 to 105 degrees
Fahrenheit. The product is then recommended to be spread evenly on the surface as a flood coat with a
squeegee or rollers and allowed to absorb completely into the concrete substrate (Euclid Chemical
Company. 2019a. b, 2018).
Note these listed examples are not all inclusive of every product under this COU, and that EPA expects
that these types of products would be purchased by commercial operations and applied by professional
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contractors in various commercial settings. The Agency also expects that some of these products are
likely to be used for industrial applications; however, they would be available and used in smaller scale
commercial settings for similar purposes (e.g., protection on structural components, construction).
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a process
regulator in paints and coating manufacturing, which has been recategorized in the COU table to
"stabilizing agent" after discussions with the company that purchased the previous 2016 reporting
company (U.S. EPA. 2024ai). See Appendix D for more information on the changes from the COUs
from the Final Scope of the Risk Evaluation for Dicyclohexyl Phthalate (DCHP); CASRN 84-61-7 (U.S.
EPA. 2020bY
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a stabilizing agent
in paints and coating manufacturing.
E.20 Commercial Use - Other Articles with Routine Direct Contact During
Normal Use Including Rubber Articles; Plastic Articles (Hard)
This COU is referring to the commercial use of DCHP in various rubber and plastic articles that are
intended for routine direct contact. The 2020 CDR reporting category "other articles with routine direct
contact during normal use including rubber articles; plastic articles (hard)" is intended to capture items
such as gloves, boots, clothing, rubber handles, gear levers, steering wheels, handles, pencils, and
handheld device casing. Given the use of DCHP as a general-purpose plasticizer for PVC and non-PVC
applications, EPA expects that this use of DCHP has been identified in previous CDR reports as "plastic
and rubber products not covered elsewhere."
According to information provided to EPA, DCHP is used as a plasticizer in plastic and rubber products
used in the aerospace industry (AIA. 2019) and a variety of transportation equipment such as both
vehicles production parts and replacement parts (e.g., brake calipers, fender shim, disc brake assembly)
(MEMA. 2019). The Alliance of Automobile Manufacturers and the Motor & Equipment Manufacturers
Association did explain that "[t]he average scope of the relative mass of DCHP in the parts from the
Alliance's data collection is 0.24 gram. Excluding body/exterior parts, that average drops below 0.01
gram" (MEMA. 2019V
As such, workers would be expected to handle or touch products covered by this COU with their hands
and be exposed to DCHP through dermal contact.
Examples of CDR Submissions
In 2016 one CDR company reported the commercial use of DCHP (CASRN 84-61-7) in plastic and
rubber products not covered elsewhere.
In 2020 the same CDR company reported the commercial use of DCHP (CASRN 84-61-7) as a
plasticizer in other articles with routine direct contact during normal use including rubber articles;
plastic articles (hard), which is a further refined description compared to the 2016 CDR cycle code of
"plastic and rubber products not covered elsewhere."
E.21 Consumer Use - Adhesives and Sealants
This COU is referring to the consumer use of DCHP in adhesives and sealants. According to
information provided to EPA, the American Coatings Association explained that DCHP is a plasticizer,
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additive, and impurity in adhesives in amounts less than 1 percent (ACA. 2019). EPA has identified
DCHP in a multi-purpose nitrocellulose household glue at one to five percent with suggested
applications of china, vases, plastic, wood, metal, and crafts (ITW Permatex. 2024; Midwest
Technology Products. 2024; ITW Permatex. 2021) as well as adhesives and sealants meant for the
industrial and commercial automotive industry that are also available to consumer customers (Lord
Corporation. 2021. 2020. 2017). For example, the two-part metal bonding adhesive is meant for use in
various elements of an automotive (e.g., panel bonding, weld and rivet bonding of quarter panels, rear
body panels, roof panels, door skins, van side panels and outer truck bed panels) and has a DCHP
concentration of one to five percent (Lord Corporation. 2017). EPA has also identified various two-part
adhesive anchoring systems, such as a two-part hammer-capsule system designed for use in the
installation of a threaded rod into solid concrete and masonry materials that contained DCHP
concentrations of 1 to 2.5 percent (DeWalt. 2024b. 2022. 2020). as well as another two-part polyester
liquid system to be used once again in construction and building environments (MKT. 2023a. b, 2018).
Aside from the household glue, EPA expects that the primary use of several of these products is meant
to occur in industrial/commercial applications only; however, the Agency notes that several of these
products can be sourced by DIY consumers through various online vendors (DeWalt. 2024a; Lord
Corporation. 2024; MKT. 2024).
This COU was not reported in the 2016 or 2020 CDR cycles.
E.22 Consumer Use - Other Articles with Routine Direct Contact During
Normal Use Including Rubber Articles; Plastic Articles (Hard)
This COU is referring to the consumer use of DCHP in various rubber and plastic articles that are
intended for consumer use through routine direct contact. The 2020 CDR reporting category "other
articles with routine direct contact during normal use including rubber articles; plastic articles (hard)" is
intended to capture items such as gloves, boots, clothing, rubber handles, gear levers, steering wheels,
handles, pencils, and handheld device casing. Given the use of DCHP as a general-purpose plasticizer
for PVC and non-PVC applications, EPA expects that this use of DCHP has been identified in previous
CDR reports as "plastic and rubber products not covered elsewhere."
According to information provided to EPA, DCHP is used as a plasticizer in plastic and rubber products
used in the aerospace industry (AIA. 2019) as well as a variety of transportation equipment such as both
vehicles production parts and replacement parts (MEMA. 2019). The Alliance of Automobile
Manufacturers and the Motor & Equipment Manufacturers Association did explain that "[t]he average
scope of the relative mass of DCHP in the parts from the Alliance's data collection is 0.24 gram.
Excluding body/exterior parts, that average drops below 0.01 gram" (MEMA. 2019).
According to additional information provided to EPA in 2021, DCHP (referred to in this case as Uniplex
250) has been used as an article in a "range of construction products-boards" (LANXESS. 2021). These
boards are presumed to be used in a variety of commercial applications and settings; however, could still
be a source of exposure for consumers.
As such, consumers would be expected to handle or touch products covered by this COU with their
hands and be exposed to DCHP through dermal contact.
Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the consumer use of DCHP (CASRN 84-61-7) in plastic
and rubber products not covered elsewhere.
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In the 2020 CDR cycle, the same company reported the consumer use of DCHP (CASRN 84-61-7) as a
plasticizer in other articles with routine direct contact during normal use including rubber articles;
plastic articles (hard), which is a further refined description compared to the 2016 CDR cycle code of
"plastic and rubber products not covered elsewhere."
E.23 Consumer Use - Other Consumer Articles that Contain DCHP from:
Inks, Toner, and Colorants; Paints and Coatings; and Adhesives and
Sealants
This COU is referring to the consumer use of articles that contain DCHP from inks, toner, and colorants,
paints and coatings and adhesives and sealants.
According to information provided to EPA in 2021, DCHP (referred to in this case as Uniplex 250) has
been used as an element of PVC inks/PVC plastisol formulations (LANXESS. 2021; U.S. EPA. 2019e).
Uniplex 250 is also marketed as being used as a polymer additive in labels and printing ink formulations
(Hallstar Website) and has been used as part of the screen-printing process for textiles (Gans Ink and
Supply. 2018). EPA expects consumers to exposed to DCHP through various products, such as textiles,
labels, packaging, etc.
The Agency has also identified several examples of commercial paints and coatings that already have
DCHP incorporated as a plasticizer or combine two (or even multiple) components where DCHP acts as
a phlegmatizer with BPO in unsaturated polyesters or MMA systems (U.S. EPA. 2024ai). These paints
and coatings that utilize DCHP, are often applied in commercial settings such as in roofing,
construction, and in cement/protection for high traffic areas (etc.)—often to provide waterproofing, UV
protection and/or chemical resistance. In particular, EPA identified a product that is used as a vehicular
and pedestrian traffic coating system, specifically designed for use in parking structures, balconies,
stadium seating, walkways, plaza decks, etc. (Hydro-Gard. 2024. 2017a. b, 2012a. b). EPA expects
consumers to be exposed to DCHP through this coating in areas where consumer access is presumed,
such as balconies and stadium seating.
Additionally, DCHP is used during the cellulose film production to bathe or coat the film, giving it
barrier properties as well as promoting heat seal. This cellulose film is then used in a variety of labeling,
and packaging end uses (U.S. EPA. 2020c; Earthiustice. 2019). Any packaging or cellulose film end
uses that are not subject to the U.S. Food and Drug Administration (FDA) regulations, would be
captured under this COU. EPA would expect dermal exposure to DCHP through handling cellulose film.
Finally, EPA has identified commercial or industrial adhesives and sealants that already have DCHP
incorporated as a plasticizer or combine a two-part adhesive where DCHP acts as a phlegmatizer in
unsaturated polyesters or MMA systems (U.S. EPA. 2024ai). The American Coatings Association
explained that DCHP is a plasticizer, additive, and impurity in adhesives in amounts less than one
percent (ACA. 2019). According to information provided to EPA, DCHP is used as an adhesive within
the aerospace industry (AIA. 2019). and an adhesive sealant for body panel assemblies and parts by
automobile manufacturers applications (MEMA. 2019). EPA has also identified various industrial and
commercial applications of adhesives and sealants in the construction industry, electronics etc. As a
result, the Agency expects consumer to be exposed to DCHP through various complex articles that used
an adhesive and sealant that contained DCHP, such as electronics, cars, airplanes, and
building/construction materials.
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Examples of CDR Submissions
In the 2016 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a plasticizer in
printing ink manufacturing. One company reported the use of DCHP as a process regulator in paints and
coating manufacturing, which has been recategorized in the COU table to "stabilizing agent" after
discussions with the company that purchased the previous 2016 reporting company (U.S. EPA. 2024ai).
Another company reported the use of DCHP as an adhesive and sealant chemicals in adhesive
manufacturing.
In the 2020 CDR cycle, one company reported the use of DCHP (CASRN 84-61-7) as a stabilizing agent
in paints and coating manufacturing and one company reported the use of DCHP as a plasticizer in
adhesive manufacturing.
E.24 Disposal
Each of the COUs of DCHP may generate waste streams of the chemical. For purposes of the DCHP
risk evaluation, this COU refers to the DCHP in a waste stream that is collected from facilities and
households and are unloaded at and treated or disposed at third-party sites. This COU also encompasses
DCHP contained in wastewater discharged by consumers or occupational users to a POTW or other,
non-POTW for treatment, as well as other wastes.
DCHP is expected to be released to other environmental media, such as introductions of biosolids to soil
or migration to water sources, through waste disposal (e.g., disposal of formulations containing DCHP,
plastic and rubber products, and transport containers). Disposal may also include destruction and
removal by incineration. Recycling of DCHP and DCHP containing products is considered a different
COU. Environmental releases from industrial sites are assessed in each COU.
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Appendix F DRAFT OCCUPATIONAL EXPOSURE VALUE
DERIVATION
EPA has calculated a draft 8-hour existing chemical occupational exposure value to summarize the
occupational exposure scenario and sensitive health endpoints into a single value. This calculated draft
value may be used to support risk management efforts for DCHP under TSCA section 6(a), 15 U.S.C.
section 2605. EPA calculated the draft value rounded to 0.63 mg/m3 for inhalation exposures to DCHP
as an 8-hour time-weighted average (TWA) and for consideration in workplace settings (see Appendix
F.l) based on the acute, non-cancer human equivalent concentration (HEC) for developmental toxicity
{i.e., phthalate syndrome-related effects on the developing male reproductive system).
TSCA requires risk evaluations to be conducted without consideration of costs and other non-risk
factors, and thus this draft occupational exposure value represents a risk-only number. If risk
management for DCHP follows the finalized risk evaluation, EPA may consider costs and other non-risk
factors, such as technological feasibility, the availability of alternatives, and the potential for critical or
essential uses. Any existing chemical exposure limit used for occupational safety risk management
purposes could differ from the draft occupational exposure value presented in this appendix based on
additional consideration of exposures and non-risk factors consistent with TSCA section 6(c).
This calculated draft value for DCHP represents the exposure concentration below which exposed
workers and ONUs are not expected to exhibit any appreciable risk of adverse toxicological outcomes,
accounting for PESS. It is derived based on the most sensitive human health effect (i.e., effects on the
developing male reproductive system) and exposure duration (i.e., acute) relative to benchmarks and a
standard occupational scenario assumption of an 8-hour workday.
EPA expects that at the draft occupational exposure value of 0.047 ppm (0.63 mg/m3), a worker or ONU
also would be protected against developmental toxicity from intermediate and chronic duration
occupational exposures if ambient exposures are kept below this draft occupational exposure value. The
Agency has not separately calculated a draft short-term (i.e., 15-minute) occupational exposure value
because EPA did not identify hazards for DCHP associated with this very short duration.
EPA did not identify a government-validated method for analyzing DCHP in air.
The Occupational Safety and Health Administration (OSHA) has not set a permissible exposure limit
(PEL) as an 8-hour TWA for DCHP. EPA located several occupational exposure limits for DCHP
(CASRN 84-61-7) in other countries (https://ilv.ifa.dguv.de/limitvalues/20258). Identified 8-hour TWA
values range from 3 mg/m3 in Denmark to 5 mg/m3 in Austria, Ireland, New Zealand, South Africa, and
the United Kingdom. Additionally, EPA found that New Zealand and the United Kingdom have an
established occupational exposure limit of 5 mg/m3 (8-hour TWA) in each country's code of regulation
that is enforced by each country's worker safety and health agency.
F.l Draft Occupational Exposure Value Calculations
This appendix presents the calculations used to estimate draft occupational exposure values using inputs
derived in this draft risk evaluation. Multiple values are presented below for hazard endpoints based on
different exposure durations. For DCHP, the most sensitive occupational exposure value is based on
non-cancer developmental effects and the resulting 8-hour TWA is rounded to 0.63 mg/m3.
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Draft Acute Non-cancer Occupational Exposure Value
The draft acute occupational exposure value (EVaCute) was calculated as the concentration at which the
acute MOE would equal the benchmark MOE for acute occupational exposures using EquationApx
F-l:
Equation Apx F-l.
HECacute ATHECacute IRresting
Jh jfc
Benchmark MOEacute ED I Rworkers
24/i n£10rm3
0.95 ppm ~T~ 0-6125—-
* Sir * ¥- = 0-047 ppm
30 8h m3
d i"Zb hr
/mgx _ EV ppm * MW _ 0-047 ppm *330.4^ _ n mg
acute vm3 / MolarVolume 24 45 —^— ' m3
mol
Draft Intermediate Non-cancer Occupational Exposure Value
The draft intermediate occupational exposure value (EVintermediate) was calculated as the concentration at
which the intermediate MOE would equal the benchmark MOE for intermediate occupational exposures
using Equation Apx F-2:
Equation Apx F-2.
gy HEQntermediate ^ AThec intermediate^ IRresting
intermediate Benchmark MOfjntermediate ED*EF IRworkers
24/i m3
0.95 ppm — *30d 0.6125-^ mg
= — * -77; * 5— = 0.063 ppm = 0.86 —7
30 22d 1.25^
a hr
Draft Chronic Non-cancer Exposure Value
The draft chronic occupational exposure value (EVchronic) was calculated as the concentration at which
the chronic MOE would equal the benchmark MOE for chronic occupational exposures using
EquationApx F-3:
Equation Apx F-3.
gy HECciironjc ^ AThec chronic ^ IRresting
chronic Benchmark MOEchronic ED*EF*WY IRworkers
24h 365d n.m3
a qr nnm ———* *40 v*0.6125—— mc
0.95 ppm ^ d y hr — — n no m£
¦ * ¦
0.068 ppm = 0.92 —|
Where:
30 250d . orm ' ' m3
3U —* *40v*1.25—
d y hr
A Thee ate = Averaging time for the POD/HEC used for evaluating non-cancer
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A TnECintermediate
A ThECchronic
Benchmark M()I\
¦acute
Benchmark MOEi„termediate =
Benchmark MOEchromc =
E\ acute
E\ intermediate
E V chronic —
ED
EF
HEC
IR
Molar Volume =
MW
WY
acute occupational risk based on study conditions and HEC
adjustments (24 h/day).
Averaging time for the POD/HEC used for evaluating non-cancer
intermediate occupational risk based on study conditions and/or
any HEC adjustments (24 h/day for 30 days).
Averaging time for the POD/HEC used for evaluating non-cancer
chronic occupational risk based on study conditions and/or HEC
adjustments (24 h/day for 365 days/year) and assuming the
same number of years as the high-end working years (WY, 40
years) for a worker.
Acute non-cancer benchmark margin of exposure, based on the
total uncertainty factor of 30
Intermediate non-cancer benchmark margin of exposure, based on
the total uncertainty factor of 30
Chronic non-cancer benchmark margin of exposure, based on the
total uncertainty factor of 30
Acute occupational exposure value
Intermediate occupational exposure value
Chronic occupational exposure value
Exposure duration (8 h/day)
Exposure frequency (1 day for acute, 22 days for intermediate, and
250 days/year for chronic and lifetime)
Human equivalent concentration for acute, intermediate, or chronic
non-cancer occupational exposure scenarios
Inhalation rate (default is 1.25 m3/h for workers and 0.6125 m3/h
assumed from "resting" animals from toxicity studies)
24.45 L/mol, the volume of a mole of gas at 1 atm and 25 °C
Molecular weight of DCHP (330.4 g/mole)
Working years per lifetime at the 95th percentile (40 years).
Unit conversion:
1 ppm = 13.51 mg/m (see equation associated with the EVacute calculation)
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