EPA Document# EPA-740-R-21-003
February 2022

United States	Office of Chemical Safety and

v/crM Environmental Protection Agency	Pollution Prevention

Final Scope of the Risk Evaluation for
Octamethylcyclotetra- siloxane
(Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-)

(D4)

CASRN 556-67-2

I

l-UC-

1 nv

/ \ /

I	Si CH:

/ \ /
O :

I CH,

February 2022


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TABLE OF CONTENTS

ACKNOWLEDGEMENTS	6

ABBREVIATIONS AND ACRONYMS	7

EXECUTIVE SUMMARY	9

1	INTRODUCTION	12

2	SCOPE OF THE EVALUATION	13

2.1	Reasonably Available Information	13

2.1.1	Search of Gray Literature	14

2.1.2	Search of Literature from Publicly Available Databases (Peer-Reviewed Literature)	14

2.1.3	Search of TSCA Submissions	24

2.2	Conditions of Use	26

2.2.1	Categories and Subcategories of Conditions of Use Included in the Scope of the Risk
Evaluation	26

2.2.2	Activities Excluded from the Scope of the Risk Evaluation	29

2.2.3	Production Volume	30

2.2.4	Overview of Conditions of Use and Life Cycle Diagram	31

2.3	Exposures	33

2.3.1	Physical and Chemical Properties	33

2.3.2	Environmental Fate and Transport	35

2.3.3	Releases to the Environment	36

2.3.4	Environmental Exposures	36

2.3.5	Occupational Exposures	36

2.3.6	Consumer Exposures	37

2.3.7	General Population Exposures	38

2.4	Hazards (Effects)	39

2.4.1	Environmental Hazards	39

2.4.2	Human Health Hazards	39

2.5	Potentially Exposed or Susceptible Subpopulations	40

2.6	C onceptual Model s	41

2.6.1	Conceptual Model for Industrial and Commercial Activities and Uses	41

2.6.2	Conceptual Model for Consumer Activities and Uses	43

2.6.3	Conceptual Model for Environmental Releases and Wastes: Potential Exposures and
Hazards	45

2.7	Analysis Plan	47

2.7.1	Physical and Chemical Properties and Environmental Fate	47

2.7.2	Exposure	48

2.7.2.1	Environmental Releases	48

2.7.2.2	Environmental Exposures	50

2.7.2.3	Occupational Exposures	51

2.7.2.4	Consumer Exposures	53

2.7.2.5	General Population	54

2.7.3	Hazards (Effects)	56

2.7.3.1	Environmental Hazards	56

2.7.3.2	Human Health Hazards	57

2.7.4	Summary of Risk Approaches for Characterization	60

2.8	Peer Review	61

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REFERENCES	62

APPENDICES	70

Appendix A ABBREVIATED METHODS FOR SEARCHING AND SCREENING	70

A. 1 Literature Search of Publicly Available Databases	70

A. 1.1 Search Term Genesis and Chemical Verification	70

A. 1.2 Publicly Available Database Searches	71

A, 1,2,1 Query Strings for the Publicly Available Database Searches on D4	72

A. 1.2.2 Data Prioritization for Environmental Hazard, Human Health Hazard, Fate, and

Physical Chemistry	75

A. 1.2.3 Data Prioritization for Occupational Exposures and Environmental Releases and Gen

Pop, Consumer, and Environmental Exposures	76

A.2 Peer-Reviewed Screening Process			76

A.2.1 Inclusion/Exclusion Criteria	76

A.2.1.1 PECO for Environmental and Human Health Hazards	77

A.2.1.2 PECO for Consumer, Environmental, and General Population Exposures	80

A.2.1.3 RESO for Occupational Exposure and Environmental Releases	81

A.2.1.4 PESO for Fate and Transport	83

A.2.1.5 Generation of Hazard Heat Maps	86

A.3 Gray Literature Search and Screening Strategies.....									86

A.3.1 Screening of Gray Literature	87

A.3.2 Initial Screening of Sources Using Decision Logic Tree	88

A.3.3 TSCA Submission Searching and Title Screening	89

A.3.4 Gray Literature Search Results for D4	90

A.4 Summary of Literature Cited in the SEHSC Submission	92

Appendix B PHYSICAL AND CHEMICAL PROPERTIES OF D4	93

Appendix C ENVIRONMENTAL FATE AND TRANSPORT PROPERTIES OF D4	94

Appendix D REGULATORY HISTORY	100

D. 1 Federal Laws and Regulations			100

D.2 State Laws and Regulations 																				102

D.3	International Laws and Regulations	102

Appendix E PROCESS, RELEASE, AND OCCUPATIONAL EXPOSURE INFORMATION 104

E.l	Process Information.					....104

E. 1.1 Manufacture (Including Import)	104

E.l. 1.1 Domestic Manufacturing	104

E.l. 1.2 Import	104

E. 1.2 Processing and Distribution	104

E. 1.2.1 Reactant or Intermediate	104

E. 1.2.2 Incorporated into a Formulation, Mixture, or Reaction Product	105

E.l.2.3 Repackaging	105

E.l.3 Uses	105

E.l.3.1 Aircraft Maintenance	105

E.1.3.2 Adhesives and Sealants	105

E.l.3.3 Automotive Care Products	105

E. 1.3.4 Furnishing, Cleaning, Treatment/Care Products	106

E.l.3.5 Ink, Toner, and Colorant Products	106

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E. 1.3.6 Laboratory Chemicals	106

E.l.3,7 Paints and Coatings	106

E. 1.3.8 Plastic and Rubber Products	106

E.1.4 Disposal	106

E.2 Preliminary Occupational Exposure Data	108

Appendix F SUPPORTING INFORMATION - CONCEPTUAL MODEL FOR

INDUSTRIAL AND COMMERCIAL ACTIVITIES AND USES	109

Appendix G SUPPORTING INFORMATION - CONCEPTUAL MODEL FOR

CONSUMER ACTIVITIES AND USES	116

Appendix H SUPPORTING INFORMATION - CONCEPTUAL MODEL FOR

ENVIRONMENTAL RELEASES AND WASTES	123

LIST OF TABLES

Table 2-1. Results of Title Screening of Submissions to EPA under Various Sections of TSCA	25

Table 2-2. Categories and Subcategories of Conditions of Use Included in the Scope of the Risk

Evaluation	26

Table 2-3. Physical and Chemical Properties for D4	33

Table 2-4. Categories and Sources of Environmental Release Data	48

Table 2-5. Potential Sources of Occupational Exposure Data	51

LIST OF FIGURES

Figure 2-1. Gray Literature Tags by Discipline for D4	14

Figure 2-2. Peer-Reviewed Literature - Physical and Chemical Properties Search Results for D4	16

Figure 2-3. Peer-Reviewed Literature - Fate and Transport Search Results for D4	17

Figure 2-4. Peer-Reviewed Literature Inventory Heat Map - Fate and Transport Search Results for

D4 and/or Degradants	18

Figure 2-5. Peer-Reviewed Literature Inventory Tree - Engineering Search Results for D4	19

Figure 2-6. Peer-Reviewed Literature Inventory Heat Map - Engineering Search Results for D4	20

Figure 2-7. Peer-Reviewed Literature and Gray Literature - Exposure Search Results for D4	21

Figure 2-8. Peer-Reviewed and Gray Literature Inventory Heat Map -Exposure - Search Results for

D4	22

Figure 2-9. Peer-Reviewed Literature Inventory Tree - Human Health and Environmental Hazards

Search Results for D4	23

Figure 2-10. Peer-Reviewed Literature Inventory Heat Map - Human Health and Environmental

Hazards Search Results for D4	24

Figure 2-11. D4 Life Cycle Diagram	32

Figure 2-12. Box and Whisker Plots of Reported Physical and Chemical Property Values	35

Figure 2-13. D4 Conceptual Model for Industrial and Commercial Activities and Uses: Worker and

ONU Exposures and Hazards"	42

Figure 2-14. D4 Conceptual Model for Consumer Activities and Uses: Consumer Exposures and

Hazards"	44

Figure 2-15. D4 Conceptual Model for Environmental Releases and Wastes: Environmental and

General Population Exposures and Hazards"b	46

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LIST OF APPENDIX TABLES

Table_Apx A-l. Sources of Verification for Chemical Names and Structures	70

TableApx A-2. Summary of Data Sources, Search Dates, and Number of Peer-Reviewed Literature

Search Results for Octamethylcyclotetrasiloxane (D4)	72

Table Apx A-3. Summary of Supplemental Data Sources, Search Dates, and Number of Peer-

Reviewed Literature Search Results for Octamethylcyclotetrasiloxane (D4)	73

Table Apx A-4. Hazards Title and Abstract and Full-Text PECO Criteria for D4	77

Table Apx A-5. Major Categories of "Potentially Relevant" Supplemental Materials for D4	79

Table Apx A-6. Generic Inclusion Criteria for the Data Sources Reporting Exposure Data on General

Population, Consumers, and Environmental Receptors	80

Table Apx A-7. Inclusion Criteria for Data Sources Reporting Engineering and Occupational

Exposure Data	81

Table Apx A-8. Engineering, Environmental Release, and Occupational Data Necessary to Develop

the Environmental Release and Occupational Exposure Assessments	82

Table Apx A-9. Inclusion Criteria for Data or Information Sources Reporting Environmental Fate

and Transport Data	84

Table Apx A-10. Fate Endpoints and Associated Processes, Media, and Exposure Pathways

Considered in the Development of the Environmental Fate Assessment	85

Table_Apx A-l 1. Decision Logic Tree Overview	89

Table_Apx A-12. Gray Literature Sources that Yielded Results for D4	90

Table Apx B-l. Physical and Chemical Properties of D4	93

Table Apx C-l. Environmental Fate and Transport Properties of D4	94

Table_Apx D-l. Federal Laws and Regulations	100

Table_Apx D-2. State Laws and Regulations	102

Table Apx D-3. Regulatory Actions by Other Governments, Tribes, and International Agreements... 102

Table Apx F-l. Worker and ONU Exposure Conceptual Model Supporting Table	109

Table Apx G-l. Consumer Exposure Conceptual Model Supporting Table	116

Table Apx H-l. General Population and Environmental Exposure Conceptual Model Supporting

Table	123

LIST OF APPENDIX FIGURES

FigureApx A-l. Decision Logic Tree Used to Screen Gray Literature Results	88

FigureApx A-2. Venn Diagram of Literature Identified by EPA vs. the SEHSC Submission	92

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ACKNOWLEDGEMENTS

This report was developed by the United States Environmental Protection Agency (U.S. EPA), Office of
Chemical Safety and Pollution Prevention (OCSPP), Office of Pollution Prevention and Toxics (OPPT).

Acknowledgements

The OPPT Assessment Team gratefully acknowledges participation or input from intra-agency
reviewers that included multiple offices within EPA; inter-agency reviewers that included multiple
federal agencies; and assistance from EPA contractors Battelle (Contract No. EPW-16-017 WA 4-14);
ERG (Contract No. EP-W-12-006); ICF (Contract No.68HERC19D0003); Abt Associates (Contract No.
EP-W-16-009); and SRC (Contract No. 68HERH19F0213).

Docket

Supporting information can be found in public docket, Docket ID: EPA-HQ-OPPT-2018-0443.
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.

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ABBREVIATIONS AND ACRONYMS

ADME

Absorption, distribution, metabolism, and excretion

ADAF

Age-dependent adjustment factors

BAF

Bioaccumulation factor

BCF

Bioconcentration factor

BMF

Biomagnification factor

BOD

Biochemical oxygen demand

BW34

Body weight scaling to the 3/4 power

CASRN

Chemical Abstracts Service Registry Number

CBI

Confidential business information

CDR

Chemical Data Reporting

CFR

Code of Federal Regulations

ChemSTEER Chemical Screening Tool for Exposure and Environmental Releases

coc

Concentration(s) of concern

CPCat

Chemical and Product Categories

CPSC

Consumer Product Safety Commission

CSCL

Chemical Substances Control Law

CSF

Cancer slope factor

CWA

Clean Water Act

D4

Octamethylcyclotetra- siloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-)

DMSD

Dimethylsilanediol

ECHA

European Chemicals Agency

EC

European Commission

ECx

Effective Concentration that causes a response that is x% of the maximum

EPA

Environmental Protection Agency

ERG

Eastern Research Group

ESD

Emission Scenario Document

EU

European Union

FDA

Food and Drug Administration

FFDCA

Federal Food, Drug, and Cosmetic Act

FR

Federal Register

GC

Gas chromatography

GDIT

General Dynamics Information Technology

GS

Generic Scenario

FLAWC

Health Assessment Workplace Collaborative

HERO

Health and Environmental Research Online (Database)

Hg

Mercury

HHE

Health Hazard Evaluation

HQ

Headquarters

HSDB

Hazardous Substances Data Bank

ICF

ICF (a global consulting company)

IMAP

Inventory Multi-Tiered Assessment and Prioritisation (Australia)

IMIS

Integrated Management Information System

IUR

Inhalation unit risk

Koc

Organic carbon: water partition coefficient

Kow

Octanol: water partition coefficient

LCso

Lethal Concentration of 50% test organisms

LOAEL

Lowest observed adverse effect level

LOEC

Lowest observed effect concentration

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MITI

Ministry of International Trade and Industry

MOA

Mode of action

MOE

Margin of exposure

MP

Melting point

MRSA

Maine Revised Statutes Annotated

NHANES

National Health and Nutrition Examination Survey

NICNAS

National Industrial Chemicals Notification and Assessment Scheme (Australia)

NIOSH

National Institute for Occupational Safety and Health

NITE

National Institute of Technology and Evaluation

NLM

National Library of Medicine

NOAEL

No observed adverse effect level

NOEC

No observed effect concentration

NPDES

National Pollutant Discharge Elimination System

OCSPP

Office of Chemical Safety and Pollution Prevention

OECD

Organisation for Economic Co-operation and Development

OEL

Occupational Exposure Limit

ONU

Occupational non-user

OPPT

Office of Pollution Prevention and Toxics

OSF

Oral slope factor

OSHA

Occupational Safety and Health Administration

PBPK

Physiologically based pharmacokinetic

PBT

Persistent, bioaccumulative, toxic

PDMS

Polydimethylsiloxane

PECO

Population, exposure, comparator, and outcome

PESO

Pathways and processes, exposure, setting/scenario, and outcomes

PESS

Potentially exposed or susceptible subpopulation(s)

POD

Point(s) of departure

POTW

Publicly owned treatment works

PPE

Personal protective equipment

PVC

Polyvinyl chloride

RCRA

Resource Conservation and Recovery Act

REACH

Registration, Evaluation, Authorisation and Restriction of Chemicals (European Union)

RESO

Receptor, exposure, setting/scenario, and outcome

RQ

Risk quotient

SDS

Safety Data Sheet

SEHSC

Silicones Environmental, Health, and Safety Center

SMILES

Simplified molecular-input line-entry system

SRC

SRC, Inc., formerly Syracuse Research Corporation

T1/2

Half-life

TCCR

Transparent, clear, consistent, and reasonable

TIAB

Title and abstract

TMF

Trophic magnification factor(s)

TRI

Toxics Release Inventory

TSCA

Toxic Substances Control Act

U.S.C.

United States Code

VP

Vapor pressure

WS

Water solubility

WWTP

Wastewater treatment plant

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EXECUTIVE SUMMARY

On March 19, 2020, EPA received a request, pursuant to 40 CFR 702.37, from Dow Silicones
Corporation, Elkem Silicones USA Corporation, Evonik Corporation, Momentive Performance
Materials, Shin-Etsu Silicones of America, Inc., and Wacker Chemical Corporation through the
American Chemistry Council's Silicones Environmental, Health, and Safety Center (SEHSC), to
conduct a risk evaluation for octamethy 1 cyclosi 1 oxane (D4) (CASRN 556-67-2) (Docket ID: EPA-HQ-
QPPT-2018-0443). This chemical substance is listed in the 2014 update to the Toxic Substances Control
Act (TSCA) Work Plan as "octamethylcyclotetra- siloxane" and is assigned CA Index Name
"Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-." It is most commonly referred to as
Octamethylcyclotetrasiloxane and will be abbreviated in this document as "D4 " On June 17, 2020, EPA
opened a 45-day public comment period to gather information relevant to the requested risk evaluation.
EPA reviewed the request (along with additional information received during the public comment
period) and assessed whether the circumstances identified in the request constitute conditions of use
under 40 CFR 702.33 and whether those conditions of use warrant inclusion within the scope of a risk
evaluation for D4. EPA determined that the request meets the applicable regulatory criteria and
requirements, as prescribed under 40 CFR 702.37. The Agency granted the request on October 6, 2020.

The first step of the risk evaluation process is the development of the scope document. EPA published
the Draft Scope of the Risk Evaluation for Octamethyltetra- siloxane (D4) CASRN 556-67-2 on
September 8, 2021 (EPA Document No. EPA-740-D-21-001) and provided a 45-day comment period on
the draft scope per 40 CFR 702.41(c)(7). EPA has considered comments received (Docket ID:	Q~

QPPT-2018-0443) during the public comment period to inform the development of this final scope
document, and the public comments received will continue to inform the development of the risk
evaluation for D4. This document fulfills the statutory and regulatory requirements under the Toxic
Substances Control Act (TSCA) to issue a final scope document per TSCA section 6(b)(4)(D) and 40
CFR 702.41(c)(8). The scope for D4 includes the following information: the conditions of use,
potentially exposed or susceptible subpopulations (PESS), hazards, and exposures that EPA plans to
consider in this risk evaluation, along with a description of the reasonably available information and
science approaches EPA plans to use in the risk evaluation, a conceptual model, an analysis plan, and
the plan for peer review of the draft risk evaluation for this chemical substance.

General Information

D4 is a colorless, oily liquid with an annual total production volume in the United States in 2015
between 750 million and 1 billion pounds (	020a).

Reasonably Available Information

To inform the development of this scope document, EPA leveraged the data and information sources
identified within the SEHSC submission requesting EPA conduct the risk evaluation for D4 (Docket ID:
EPA-HQ-QPPT-2018-0443). as well as any other data or information sources identified throughout the
course of the submission and review process for this manufacturer requested risk evaluation. To further
develop this scope document, EPA conducted a comprehensive search to identify and screen multiple
evidence streams {i.e., chemistry, fate, release and engineering, exposure, hazard), and the search and
screening results to date are provided in Section 2.1.

Conditions of Use

EPA plans to evaluate manufacturing (including importing); processing; distribution in commerce;
industrial, commercial, and consumer uses; and disposal of D4 in the risk evaluation. D4 is
manufactured (including imported) in the United States. The chemical is processed as a reactant;
incorporated into a formulation, mixture, or reaction product; and incorporated into articles. The

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identified processing activities also include the repackaging and recycling of D4. D4 is primarily used to
make other silicone chemicals and as an ingredient in consumer products regulated by the Federal Food,
Drug, and Cosmetic Act (FFDCA). Commercial and consumer uses were identified including adhesives
and sealants, automotive care products, laundry and dishwashing products, paints and coatings, and
other plastic and rubber products.

Some of these conditions of use were identified in the manufacturer request as circumstances on which
EPA was requested to conduct a risk evaluation. EPA identified other conditions of use from
information reported to EPA through its Chemical Data Reporting (CDR) Rule, published literature, and
consultation with stakeholders for uses currently in production and uses whose production may have
ceased. EPA presented the proposed additions of these EPA-identified conditions of use and the basis
for these proposed additions, along with the manufacturer request, for a 45-day comment period
beginning in June 2020. In the final scope, EPA has added the following conditions of use due to
additional information from stakeholder outreach, public comments, and further research: processing aid
(e.g., component in an antifoaming agent); commercial use in laundry and dishwashing products; and
industrial use in general aircraft maintenance. Section 2.2 provides additional details about the
conditions of use within the scope of the risk evaluation.

Conceptual Model

The conceptual models for D4 are presented in Section 2.6. Conceptual models are graphical depictions
of the actual or predicted relationships of conditions of use, exposure pathways (e.g., media), exposure
routes (e.g., inhalation, dermal, oral), hazards, and receptors throughout the life cycle of a chemical
substance. EPA considered reasonably available information, information received in the SEHSC
submission, as well as public comments received on the draft scope document for D4 in finalizing the
exposure pathways, routes, and hazards EPA plans to evaluate in the risk evaluation. As a result, EPA
plans to focus the risk evaluation for D4 on the following exposures, hazards, and receptors:

 Exposures (Pathways and Routes), PESS: EPA plans to evaluate releases to the environment as
well as human and environmental exposures resulting from the conditions of use of D4 that EPA
plans to consider in the risk evaluation. Exposures for D4 are discussed in Section 2.3.

Additional information gathered through systematic review searches will also inform expected
exposures.

In Section 2.6, EPA presents the conceptual models describing the identified exposures
(pathways and routes), receptors, and hazards associated with the conditions of use of D4 within
the scope of the risk evaluation.

EPA considered reasonably available information and comments received on the draft scope for
D4 in determining the human and environmental exposure pathways, routes, receptors and PESS
for inclusion in the final scope. EPA plans to evaluate the following human and environmental
exposure pathways, routes, receptors, and PESS in the scope of the risk evaluation.

-	Occupational Exposure: EPA plans to evaluate exposures to workers and occupational
non-users (ONUs) via the inhalation route, including incidental ingestion of inhaled dust,
and exposures to workers via the dermal route associated with the manufacturing,
processing, use, and disposal of D4. EPA plans to analyze dermal exposure for workers
and ONUs to mists and dust that deposit on surfaces.

-	Consumer and Bystander Exposure: EPA plans to evaluate inhalation, dermal, and oral
exposure to D4 for consumers and bystanders from the use of adhesives and sealants;
automotive care products; cleaning and furnishing care, fabric, textiles, and leather

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materials not covered elsewhere; laundry and dishwashing products; paints and coatings;
plastics and rubber products not covered elsewhere; toys, playground, and sporting
equipment; and the direct contact and/or mouthing of products or articles containing D4
for consumers.

-	General Population Exposure: EPA plans to evaluate general population exposure to D4
via the oral route from drinking water, surface water, groundwater, soil, human milk, and
fish ingestion; via the inhalation route from ambient air; and via the dermal route from
contact with drinking water, surface water, groundwater, and soil.

-	PESS: EPA plans to include children; women of reproductive age (e.g., women who may
be pregnant or breastfeeding); populations with elevated fish ingestion such as
subsistence fishing, indigenous, and native populations; workers; ONUs; consumers; and
bystanders as PESS in the risk evaluation (Section 2.5).

-	Environmental Exposure: EPA plans to evaluate exposure to D4 for aquatic and
terrestrial receptors.

 Hazards: Hazards for D4 are discussed in Section 2.4. EPA reviewed information from the
SEHSC submission requesting EPA conduct the risk evaluation for D4 (Docket ID: EPA-HQ-
OPPT-2018-0443-0004) in order to identify potential environmental and human health hazards
for D4. EPA also considered reasonably available information identified through systematic
review methods as outlined in Appendix A to determine the broad categories of environmental
and human health hazard effects to be evaluated in the risk evaluation. EPA plans to evaluate the
epidemiological and toxicological literature for D4 using revised evaluation strategies that are
described in EPA's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for
Chemical Substances (December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414).

EPA plans to evaluate all potential environmental and human health hazard effects identified for
D4 in Sections 2.4.1 and 2.4.2, respectively. The potential environmental hazard effects and
related information identified through the data screening phase of the SEHSC submission and all
other reasonably available information that EPA plans to consider for the risk evaluation for D4
include absorption, distribution, metabolism, and excretion (ADME), developmental,
gastrointestinal, mortality, neurological, nutritional and metabolic, reproductive, and respiratory
effects. Similarly, the potential human health hazard effects and related information for D4 that
EPA plans to consider for the risk evaluation include: ADME, developmental, cancer, endocrine,
gastrointestinal, hematological and immune, hepatic, mortality, neurological, nutritional and
metabolic, ocular and sensory, physiologically based pharmacokinetic modeling (PBPK), renal,
reproductive, respiratory, skin, and connective tissue.

Analysis Plan

The analysis plan for D4 is presented in Section 2.7. The analysis plan outlines the general science
approaches that EPA plans to use for the various evidence streams (i.e., chemistry, fate, release and
engineering, exposure, hazard) supporting the risk evaluation. The analysis plan is based on EPA's
knowledge of D4 to date, which includes a review of identified information as described in Section 2.1.
EPA plans to consider new information submitted by the public. Should additional data or approaches
become reasonably available, EPA may consider them for the risk evaluation.

Peer Review

The draft risk evaluation for D4 will be peer reviewed. Peer review will be conducted in accordance
with relevant and applicable methods for chemical risk evaluations, including using EPA's Peer Review
Handbook (	2015b) and other methods consistent with section 26 of TSCA (see 40 CFR

702.45).

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1 INTRODUCTION

On March 19, 2020, EPA received a request through the SEHSC from Dow Silicones Corporation,
Elkem Silicones USA Corporation, Evonik Corporation, Momentive Performance Materials, Shin-Etsu
Silicones of America, Inc., and Wacker Chemical Corporation to conduct a risk evaluation for D4
(CASRN 556-67-2) (EPA-HQ-QPPT-2018-0443) under the Frank R. Lautenberg Chemical Safety for
the 21st Century Act, the legislation that amended TSCA on June 22, 2016. On October 6, 2020, EPA
notified the requesters that the Agency had granted their manufacturer requested risk evaluation for D4.
Pursuant to 40 CFR 702.37(e)(6)(iv), the requesters had 30 days subsequent to receipt of this
notification to withdraw their request. In November 2020, upon the expiration of this 30-day period, the
risk evaluation for D4 was initiated.

Amended TSCA includes requirements and deadlines for actions related to conducting risk evaluations
of existing chemicals, including requirements for manufacturer requested risk evaluations. TSCA
section 6(b)(4) and 40 CFR 702.37 direct EPA to review manufacturer requests for risk evaluations on a
chemical substance, and upon granting the request pursuant to 40 CFR 702.37, TSCA section 6(b)(4)
directs EPA to initiate a risk evaluation on the chemical substance. TSCA section 6(b)(4)(A) directs
EPA, in conducting risk evaluations for existing chemicals, to "determine whether a chemical substance
presents an unreasonable risk of injury to health or the environment, without consideration of costs or
other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible
subpopulation identified as relevant to the risk evaluation by the Administrator, under the conditions of
use."

TSCA section 6(b)(4)(D) and implementing regulations require that EPA publish the scope of the risk
evaluation to be conducted, including the hazards, exposures, conditions of use, and PESS that the
Administrator expects to consider, within 6 months after the initiation of a risk evaluation. In addition, a
draft scope document is to be published pursuant to 40 CFR 702.41. On September 8, 2021, EPA
published the Draft Scope of the Risk Evaluation for Octamethyltetra- siloxane (D4) CASRN 556-67-2
on September 8, 2021 (EPA Document No. EPA-740-D-21-001) (86 FR 50347. September 8. 2021) for
a 45-day public comment period. After reviewing and considering the public comments received
(Docket ID: EPA-HQ-OPPT-2018-0443) on the draft scope document, EPA is now publishing this final
scope document pursuant to 40 CFR 702.41(c)(8).

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2 SCOPE OF THE EVALUATION

2.1 Reasonably Available Information

EPA conducted a comprehensive search for reasonably available information1 to support the
development of this scope document for D4. EPA leveraged the data and information sources already
identified in the SEHSC submission requesting that EPA conduct the risk evaluation for D4 (see
Appendix A.4); any additional data or information identified throughout the public comment period for
the submission and EPA's review process for this manufacturer requested risk evaluation, as laid out in
40 CFR 702.37; as well as data and information sources submitted through an enforceable consent
agreement (ECA) issued by EPA in 2014 requiring environmental monitoring data to help the Agency
better understand the presence of this chemical in the environment (EPA-HQ-Of	)). In

addition, EPA conducted an independent search for additional data and information on physical and
chemical properties, environmental fate, engineering, exposure, environmental and human health
hazards that could be obtained from the following general categories of sources:

1.	Databases containing publicly available, peer-reviewed literature;

2.	Gray literature, which is defined as the broad category of data/information sources not found in
standard, peer-reviewed literature databases, including white papers, conference proceedings,
technical reports, reference books, dissertations, information on various stakeholder websites,
and other databases; or

3.	Data and information submitted under TSCA sections 4, 5, 8(e), and 8(d), as well as "for your
information" (FYI) submissions.

Search terms were used to search each of the literature streams and gather D4 studies. These terms and
the methods used to develop them are listed in Appendix A. The studies resulting from the search
process were loaded into the EPA Health and Environmental Research Online (HERO) database and
prioritized for screening. Customized criteria (e.g., keywords, positive and negative seed papers) were
used to determine relevant literature for each of the disciplines: fate, physical and chemical properties,
engineering, exposure, and hazard. Prioritized literature was then screened according to the population,
exposure, comparator, and outcome (PECO); population, exposure, setting/scenario, and outcome
(PESO); and receptor, exposure setting/scenario, and outcome (RESO) statements listed in Appendix A.
Literature that was not prioritized for any discipline is considered off-topic and excluded from further
review. The screening process results are presented in the form of literature inventory trees and heat
maps in Section 2.1.2. The screening process was conducted based on EPA's planning, execution, and
assessment activities outlined in Appendix A.

In addition, 159 unique data and information sources identified by SEHSC in the manufacturer request
submission (Docket ID: EPA-HQ-OPPT-2018-0443-0004) (see Appendix A.4) were not included in
EPA's search results. The majority of these sources comprised industry studies, guidance documents,
and documents of a more general nature that would not be captured by EPA's search strategy described
in Appendix A.l. In some cases, sources were submitted for analogous chemicals, which were not part
of the search terms used by EPA. The Agency applies the same screening and evaluation methods to
these additional references as applied to those sources identified by EPA.

1 Reasonably available information means information that EPA possesses or can reasonably generate, obtain, and synthesize
for use in risk evaluations, considering the deadlines specified in TSCA section 6(b)(4)(G) for completing such evaluation.
Information that meets the terms of the preceding sentence is reasonably available information whether or not the information
is confidential business information, that is protected from public disclosure under TSCA section 14 (40 CFR 702.33).

Page 13 of 124


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The subsequent sections summarize the data collection activities completed to date for the general
categories of sources and topic areas (or disciplines) using literature acquisition and screening methods
as outlined in Appendix A and described in EPA's Draft Systematic Review Protocol Supporting TSCA
Risk Evaluations for Chemical Substances (December 20, 2021) (Docket No. EP A-HQ-QPPT-2021 -
0414).

2.1.1	Search of Gray Literature

EPA surveyed the gray literature and identified 69 search results relevant to EPA's risk assessment
needs for D4. Appendix A.3.4 lists the gray literature sources that yielded 69 discrete data or
information sources relevant to D4. EPA further categorized the data and information into the various
topic areas (or disciplines) supporting the risk evaluation (e.g., physical chemistry, environmental fate,
environmental hazard, human health hazard, exposure, engineering), and the breakdown is shown in
Figure 2-1. EPA will consider additional reasonably available information from gray literature if it
becomes available during the risk evaluation phase.

Gray Literature Tags by Discipline

Physical.Chemical 

Human.Health. Hazard 

&>

	Fate-

.

"o

Exposure 

Environmental.Hazard 

Engineering 

0	25	50	75	100

Percent Tagged (%)

Figure 2-1. Gray Literature Tags by Discipline for D4

The percentages across disciplines do not add up to 100%, as each source may provide data or information for
various topic areas (or disciplines). The gray literature sources depicted in this figure were those identified by
EPA using systematic review methods outlined in Appendix A.3.

2.1.2	Search of Literature from Publicly Available Databases (Peer-Reviewed Literature)

EPA has conducted searching and screening of the reasonably available literature using the process
outlined in Appendix A. This includes performing a comprehensive search of the reasonably available
peer-reviewed literature on physical and chemical properties, environmental fate and transport,
engineering (environmental release and occupational exposure), exposure (environmental, general
population, and consumer), and environmental and human health hazards of D4 and four degradation
products: octamethyltetrasiloxanediol (CASRN 3081-07-0), hexamethyltrisiloxanediol (CASRN 3663-
50-1), tetramethyldisiloxanediol (CASRN 1118-15-6), and dimethylsilanediol (DMSD) (CASRN 1066-
42-8) (see Section 2.3.2). Eligibility criteria were applied in the form of PECO, PESO, and RESO
statements to all of the reasonably available information in all of the different information pools
described in this subsection and in Section 2.1 above (see Appendix A). Included references met the
PECO, PESO, and RESO criteria, whereas excluded references did not meet the criteria (i.e., not
relevant), and supplemental material was considered as potentially relevant (see Appendix A.2). EPA
plans to evaluate the reasonably available information identified for each discipline during the
development of the risk evaluation.

Page 14 of 124


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EPA created literature inventory trees to graphically illustrate the flow of data and information sources
following full-text screening (see Figure 2-2, Figure 2-3, Figure 2-5, Figure 2-7, and Figure 2-9) for D4
and the four degradation products mentioned above. EPA used the Health Assessment Workplace
Collaborative (HAWC) tool to develop web-based literature inventory trees illustrating, through
interactive links, studies that were included or excluded. These literature inventory trees enhance the
transparency of the decisions resulting from the screening process described in Appendix A. For each of
the corresponding disciplines, the literature was tagged to be included for evaluation during the risk
evaluation. Literature inventory trees for physical and chemical properties are provided as a static
diagram (Figure 2-2). For all other disciplines, static screen captures are provided in addition to links
within each figure's caption to the interactive literature inventory trees. The links show individual
studies that were tagged as included, excluded, or supplemental. Supplemental studies did not meet all
inclusion criteria but may be considered during the risk evaluation as supporting information (see
Appendix A). These studies can be accessed through the hyperlink provided in the associated caption
below each figure. In some figures, the sum of the numbers for the various subcategories may be larger
than the broader category because some studies may be included under multiple subcategories. In other
cases, the sum of the various subcategories may be smaller than the main category because some studies
may not be depicted in the subcategories if their relevance to the risk evaluation was unclear.

In addition, EPA tabulated the number and characteristics of the data and information sources included
in the full-text screening process in the form of literature inventory heat maps for the fate, engineering,
exposure, and hazard disciplines (see Figure 2-4, Figure 2-6, Figure 2-8, and Figure 2-10, respectively).
For each of these four disciplines, a static image of the literature inventory heat map is provided, and a
link to the interactive version presented in HAWC is included in the caption below each diagram.

Page 15 of 124


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Figure 2-2. Peer-Reviewed Literature - Physical and Chemical Properties Search Results for D4

View the interactive literature inventory tree in HAWC. Data in this static figure represent references obtained
from the publicly available databases search (see Appendix A. 1.2) and from the SEHSC submission that were
included during full-text screening as of January 10, 2022. Additional data may be added to the interactive version
as they become available.

Page 16 of 124


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[21
Sorption

ncluded for Data Extraction and
Data Evaluation



Retrieved for Full-text Review

Excluded during Full-text
Review

D4 and/or Degradan

31

Bioconcentration

Biodegradation

Volatilization

Vastewater Treatment

Supplemental from Full-text
Review

Excluded during TIAB Review

Figure 2-3. Peer-Reviewed Literature - Fate and Transport Search Results for D4

View the interactive literature inventory tree in HAWC. Data in this figure represent references obtained from the
publicly available databases search (see Appendix A. 1.2) and from the SEHSC submission that were included
during full-text screening as of January 11, 2022. Additional data may be added to the interactive version as they
become available.

Page 17 of 124


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Media

Endpoint

Air

Soil, Sediment

Wastewater,
Biosolids

Water

Other

Grand Total

Bioconcentration

5

9

4

25

1

31

Biodegradation

2

10

2

10



14

Hydrolysis



2

2

5

1

8

Photolysis

9

3

2

4



14

Sorption

1

4

1

6



9

Volatilization

8

3

4

8



14

Wastewater Treatment

3

5

11

2



14

Other

4

6

2

7



9

Grand Total

26

32

20

52

2

91

Figure 2-4. Peer-Reviewed Literature Inventory Heat Map - Fate and Transport Search Results
for D4 and/or Degradants

View the interactive version in HAWC for additional study details. The column totals, row totals, and grand totals
indicate total numbers of unique references, as some references may be included in multiple cells. The various
shades of color visually represent the number of relevant references identified by exposure media or datatype.
The darker the color, the more references are available for a given exposure media or data type. Data in this figure
represent references obtained from the publicly available databases search (see Appendix A. 1.2) and from the
SEHSC submission that were included during full-text screening as of January 11, 2022. Additional data may be
added to the interactive version as they become available.

Page 18 of 124


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General Engineering
Assessment

Figure 2-5. Peer-Reviewed Literature Inventory Tree - Engineering Search Results for D4

View the interactive literature inventory tree in HAWC. Data in this figure represents references obtained from
the publicly available databases search (see Appendix A. 1.2.) and from the SEHSC submission that were included
during full-text screening as of January 7, 2022. Additional data may be added to the interactive version as they
become available.

Page 19 of 124


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Engineering Screening Results by Data Type and Evidence Type

Choose a Chemical:

Octamethylcyclotetrasiloxane (D4)

Engineering Heat Map of Octamethylcyclotetrasiloxane (D4)

Count of HERO IDs

Data Type

Evidence Tags





Description of release source

28



Release frequency

2

Environmental

Release or emission factors

20

Releases

Release quantity

8



Waste treatment methods and pollution control

17



Total

33



Chemical concentration





Exposure route





Life cycle description

2

General

Number of sites

6

Engineering

Physical form



Assessment

Process description

29



Production, import, or use volume

22



Throughput

7



Total

75



Area sampling data

28



Dermal exposure data

19



Engineering control

7



Exposure duration

10



Exposure frequency

7

Occupational
Exposures

Exposure route

32

Num ber of workers

11

Particle size characterization
Personal protective equipment

2
8



Personal sampling data

8



Physical form

21



Worker activity description

15



Total	 |

48

Grand Total

89

The column totals, row totals, and grand totals indicate total numbers of distinct references. The various shades of color visually represent the distinct
number of relevant references identified by data type or engineering evidence tag. The darker the color, the more references are available for a given data
type or engineering evidence tag.

References

46492

Q

81361

O

818319

O

1171884

O

2533248



2558926

O

3013038

o

3014985



3223678

o

3449377

o

3449521

o

3603436

o

3769448

o

3808976



3827299

o

3833136

o

3840008



3861464

o

4167493

o

4168341

o

4445826

o

4728485

o

4730751

o

5083520

o

5155525



5426551



5427151



5622705



5884316



5884333

Q

Figure 2-6. Peer-Reviewed Literature Inventory Heat Map - Engineering Search Results for D4

View the interactive version in HAWC for additional study details. Data in this figure represent references
obtained from the publicly available databases search (see Appendix A. 1.2) and from the SEHSC submission that
were included during full-text screening as of January 7, 2022. Additional data may be added to the interactive
version as they become available.

Page 20 of 124


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Monitoring Study

Figure 2-7. Peer-Reviewed Literature and Gray Literature - Exposure Search Results for D4

View the interactive literature inventory tree in HAWC. Data in this figure represents references obtained from
the publicly available database searches (see Appendix A. 1.2.); gray literature reference searches (see Appendix
A.3); and from the SEHSC submission that were included during full-text screening as of January 10, 2022.
Additional data may be added to the interactive version as they become available.

Page 21 of 124


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Exposure Screening Results by Data Type and Media

Choose a Chemical:

Octamethylcyclotetrasiloxane (D4)

Count of HERO IDs

oP

Exposure Heat Map of Octamethylcyclotetrasiloxane (D4)

Data Type

Media (group)

Monitoring
Study

Modeling
Study

Completed
Assessment

Experimental Epidemiologic
Study al Study

Database

Survey

Grand Total

Ambient Air

29

8

2

2 1





32

Biosolids/Sludge

15

2

3







17

Drinking Water





1







1

Groundwater

1











1

Sediment

28

3

4







29

Soil

14

4

2

1 2



1

17

Surface Water

16

5

4







20

Wastewater

24

3

3







26

Aquatic Species

32



2

1



1

33

Terrestrial Species

6





2



1

6

Consumer

12

3

5

6

2



18

Dietary

1



1







2

Dust

8

2

2







9

Exposure Factors

1

1

2







2

Exposure Pathway

6

3

1







8

Human Biomonitoring

8

3

1

2





13

Indoor Air

14

3

2

2





16

Isomers















Use Information





2



2



4

Land Disposal/Landfill

3

1

1







4

Grand Total

108

18

9

6 2

2

1

121

The column totals, row totals, and grand totals indicate total numbers of distinct references. The various shades of color visually represent the distinct
number of relevant references identified by exposure medium or data type. The darker the color, the more references are available for a given exposure
medium or data type.

References

448554

784251

818319

2095298

2150677

2151369

2163280

2188005

2533248

2535051

2539942

2548009

2549394

2553409

2555998

2557382

2557591

2557762

2557764

2557771

2558926

2581892

2674442

2691789

2700474

2749059

2823276

2944392

2948930

3007017


e





























Figure 2-8. Peer-Reviewed and Gray Literature Inventory Heat Map -Exposure - Search Results
for D4

View the interactive version in HAWC for additional study details. The column totals, row totals, and grand totals
indicate total numbers of unique references only, as some references may be included in multiple cells. The
various shades of color visually represent the number of relevant references identified by exposure media or data
type. The darker the color, the more references are available for a given exposure media or data type. Data in this
figure represent references obtained from the publicly available database searches (see Appendix A. 1.2); gray
literature reference searches (see Appendix A.3); and from the SEHSC submission that were included during full-
text screening as of January 10, 2022. Additional data may be added to the interactive version as they become
available.

Page 22 of 124


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th Model

;al Model

th Model

Environmental Model

th Model

Environmental Model

PECO-Re levant Isomer Study

Figure 2-9. Peer-Reviewed Literature Inventory Tree - Human Health and Environmental Hazards Search Results for D4

View the interactive literature inventory tree in HAWC. Data in this figure represent references obtained from the publicly available database searches
(see Appendix A. 1.2) and from the SEHSC submission that were included during full-text screening as of January 6, 2022. Additional data may be
added to the interactive version as they become available.

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Human Health and Environmental Hazards Screening Results for D4 by Evidence Type and Health Systems

Heat Map

References







Evidence Type





151 East Tenth Corp 1974

Health Outcomes

Human

Animal - Human
Health Model

Animal -
Environmental
Model

Plant

Grand Total

Annelin and Frye 1989
Battelle PNL 2004
Bayer AG 1990a

ADME

1

II 47

4



51

Bayer AG 1990b
Bayer AG 1991

Cancer



3





3

Cardiovascular











Bayer IT 1979

Developmental

1

19

4

1

24

Burns-Naas et al. 2002

Endocrine



13

1



14

Carnegie Mellon University 1972

Gastrointestinal

1

2

1



4

Carnegie Mellon University 1978

Hematological and Immune

3

10





12

Civo Institute Tno 1988a

Hepatic

1

15





15

Civo Institute Tno 1988b

Mortality



3

5



8

Compton 2019

Musculoskeletal











Dow Chemical 2010

Neurological



5

2



7

Dow Corning 1972

Nutritional and Metabolic



6

5



11

Dow Corning 1975a

Ocular and Sensory

2

5





7

Dow Corning 1975b

PBPK











Dow Corning 1977

Renal



3





3

Dow Corning 1979

Reproductive

1

22

2



24

Dow Corning 1982

Respiratory

2

II 43

1



45

Dow Corning 1983
Dow Corning 1984a

Skin and Connective Tissue

1

6





7

No Tag

1

20

29

3

52

Dow Corning 1984b

Grand Total

6

85

41

4

134

Hnini Cnrninn 1 OS7

The column totals, row totals, and grand totals indicate total numbers of distinct references. The various shades of color visually
represent the distinct number of relevant references identified by health outcome or evidence type. The darker the color, the more
references are available for a given health outcome or evidence type.

Evidence Types were manually extracted, and Health Systems were determined via SWIFT Review machine learning. Therefore, for
studies examining multiple Health Systems and Evidence Types, connections between health system and evidence type (e.g., which
health systems were examined under which evidence types) may not be accurately represented.

Chemical(s) Evaluated

D4 and/or degradants
D4 Only
Grand Total

O

o
o
o

o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o

The "No Tag" health outcome reflects studies with text that did not contain any of the pre-defined SWIFT Review keywords used to
identify each health outcome.

Figure 2-10. Peer-Reviewed Literature Inventory Heat Map - Human Health and Environmental
Hazards Search Results for D4

View the interactive version in HAWC for additional study details. The numbers indicate the number of studies
with title and abstract keywords related to a particular health outcome, not the number of studies that observed an
association with D4. Evidence types were manually extracted, and health outcomes were determined via machine
learning. Therefore, in studies examining multiple health outcomes and evidence types, the connections between
health outcome, and evidence type may not be accurately represented. If a study evaluated multiple health
outcomes or included multiple populations or study designs, it is shown here multiple times. Data in this figure
represent references obtained from the publicly available database searches (see Appendix A. 1.2) and those from
the SEHSC submission that were included during full-text screening as of January 6, 2022.

2.1.3 Search of TSCA Submissions

Table 2-1 presents the results of screening the titles of data sources and reports submitted to EPA under
various sections of TSCA for D4 and the four degradation products identified in Section 2.1.2. EPA
screened a total of 576 submissions2 using PECO or other statements that identify inclusion/exclusion
criteria specific to individual disciplines (see Table 2-1 for the list of disciplines). The details about the
criteria are presented in Appendix A.2.1. EPA identified 186 submissions that met the inclusion criteria

2 Of the 576 submissions. 565 were for D4. three of which also included information on the degradation products. An
additional 11 submissions were for the degradation products only.

Page 24 of 124


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in these statements and identified 145 submissions with supplemental data. EPA excluded 245
submissions because they were identified as one of the following:

	Draft report or preliminary results of a final report included based on screening criteria

	Duplicate or summary of a report received in another submission that was included based on
screening criteria

	Published report or draft manuscript for publication, which will be checked against results of the
peer or other gray literature searches

	Letter, memo, or notification containing no data

	Study amendment containing no data

	Submission on a different chemical not in scope

	Request for an extension or modification

	Development and/or details of a test method or test protocol

	Economic impact analysis

	Type of study that did not meet the screening criteria:

o Study measuring biochemical oxygen demand
o Study measuring water solubility in the presence of humic acid
o Measurement of exposure concentrations resulting from a chemical spill
o Measurement of exposure due to food processing components, medications, or use of

anti-perspirants
o Study examining effects on ozone

Table 2-1. Results of Title Screening of Submissions to EPA under Various Sections of TSCA

Discipline

Included

Supplemental"

D4

Degradants

D4

Degradants

Physical and Chemical Properties

15

0

0

0

Environmental Fate and Transport6

36

4

0

0

Environmental and General Population
Exposure

13

1

0

0

Occupational Exposure/Release
Information

10

1

0

0

Environmental Hazard6

45

3

17

0

Human Health Hazard

88

3

127

1

Individual submissions may be relevant to multiple disciplines, and so column totals may be higher than 186.
"Included submissions may contain supplemental data for other disciplines, which will be identified at full-text
review.

b One submission met the inclusion criteria for both D4 and for the degradation products.

Page 25 of 124


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2.2 Conditions of Use

The SEHSC submission requesting that EPA conduct a risk evaluation of D4 included a list of
circumstances that EPA has since determined to be conditions of use3 that warrant inclusion in the risk
evaluation for this chemical substance, pursuant to TSCA section 3(4). Following the submission of the
request for a risk evaluation of D4, EPA further assembled reasonably available information from CDR
to identify additional conditions of use for inclusion in this scope of the risk evaluation. EPA consulted a
variety of other sources (including published literature, company websites, and government and
commercial trade databases and publications) to identify uses of D4. To identify formulated products
containing D4, EPA searched for safety data sheets (SDS) using internet searches, EPA Chemical and
Product Categories (CPCat) (	) data, and other resources in which SDSs could be found.

SDSs were cross-checked with company websites to make sure that each product SDS was current. In
addition, EPA incorporated communications with companies, industry groups, and public comments on
the draft scope to supplement the use information. EPA presented the proposed additions of these EPA-
identified conditions of use and the basis for these proposed additions, along with the manufacturer
request, for a 45-day comment period in June 2020. The October 6, 2020 notification in which EPA
granted the request for a risk evaluation for D4 identified additional conditions of use that EPA plans to
include in the risk evaluation.

The categories and subcategories of conditions of use that EPA plans to consider in the risk evaluation
are presented in Section 2.2.1 (Table 2-2). The conditions of use included in the scope of the risk
evaluation are those reflected in the life cycle diagrams and conceptual models.

The circumstances on which SEHSC requested that EPA conduct a risk evaluation of D4 were
determined to be conditions of use. After gathering reasonably available information related to the
manufacture, processing, distribution in commerce, use, and disposal of D4, EPA also identified those
activities for D4 the Agency determined not to be conditions of use. These excluded activities are
described in Section 2.2.2.

2.2.1 Categories and Subcategories of Conditions of Use Included in the Scope of the Risk
Evaluation

Table 2-2 lists the conditions of use that are included in the scope of the risk evaluation.

Table 2-2. Categories and Subcategories of Conditions of Use Included in the Scope of the Risk
Evaluation

Life Cycle Stage"

Category''

Subcategory'

References

Manufacturing

Manufacturing6'



U.S. EPA. (2020a)

Importing



U.S. EPA (2020a)

Processing

Processing as a reactant

Adhesives and sealant
chemical sd

U.S. EPA. (2020a)

All other basic inorganic
chemical manufacturing6'

U.S. EPA. (2020a)

3 Conditions of use means the circumstances, as determined by the Administrator, under which a chemical substance is
intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used, or disposed of (15
U.S.C. 2602(4)).

Page 26 of 124


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Life Cycle Stage"

Category''

Subcategory'

References





All other basic organic chemical
manufacturing6'

U.S. EPA. (2020a)





All other chemical product and
preparation manufacturing6'

U.S. EPA. (2020a)





Plastic material and resin
manufacturing6'

EP A-HG-GPPT -
2018-0443-0004





Synthetic rubber manufacturing6'

EP A-HG-GPPT -
2018-0443-0004





All other basic inorganic
chemical manufacturing6'

U.S. EPA. (2020a)





All other chemical product and
preparation manufacturing6'

U.S. EPA. (2020a)





Asphalt paving, roofing, and
coating materials manufacturing

U.S. EPA. (2020a)





Computer and electronic product
manufacturing

U.S. EPA. (2020a)

Processing



Cyclic crude and intermediate
manufacturing

U.S. EPA. (2020a)



Incorporation into
formulation, mixture,
or reaction product

Electrical equipment, appliance,
and component manufacturing

U.S. EPA. (2020a)



Miscellaneous manufacturing6'

EP A-HO-OPPT -
2018-0443-0004





Paint and coating
manufacturing6'

EP A-HO-OPPT -
2018-0443-0004





Processing aid (e.g., component
in an antifoaming agent)

EPA-HO-OPPT-

2018-0443-0027





Rubber product manufacturing

U.S. EPA. (2020a)





Synthetic rubber manufacturing

U.S. EPA. (2020a)





All other basic inorganic
chemical manufacturing

U.S. EPA. (2020a)



Processing -
repackaging

All other chemical product and
preparation manufacturing

U.S. EPA. (2020a)





Miscellaneous manufacturing

U.S. EPA. (2020a)

Distribution in

Distribution in





commerce

commerce





Page 27 of 124


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Life Cycle Stage"

Category''

Subcategory'

References

Industrial use

Other uses

Aircraft maintenance

EP A-HO-OPPT -

2018-0443-0032



Adhesives and sealants

Adhesives and sealants^

U.S. EPA. (2020a)



Automotive care
products

Automotive care products^

U.S. EPA (2020a)





Fabric, textile, and leather
products not covered elsewhere^

EP A-HO-OPPT -
2018-0443-0004



Furnishing, cleaning,
treatment/care products

Cleaning and furnishing care
products^

U.S. EPA (2020a)



Laundry and dishwashing
products

;ne Specialty
Chemicals Ltd.

Commercial uses

Ink, toner, and colorant
products

Ink, toner, and colorant products

3M (2018)
3M (2019)



Laboratory chemicals

Laboratory chemicals6'

EP A-HO-OPPT -
2018-0443-0004



Paints and coatings

Paints and coatings^

U.S. EPA (2020a)



Plastic and rubber
products not covered
elsewhere

Plastic and rubber products not
covered elsewhere^

U.S. EPA (2020a)



Other

Animal grooming products

EPA-HO-OPPT-



Adhesives and sealants

Adhesives and sealants^

EPA-HO-OPPT-

2018-0443-0004



Automotive care
products

Automotive care products^

EPA-HO-OPPT-

2018-0443-0004

Consumer uses



Cleaning and furnishing care
products^

EPA-HO-OPPT-

2018-0443-0004

Furnishing, cleaning,
treatment/care products

Fabric, textile, and leather
products not covered elsewhere^

EPA-HO-OPPT-

2018-0443-0004





Laundry and dishwashing
products^

EPA-HO-OPPT-

2018-0443-0004



Packaging, paper,
plastic, hobby products

Plastic and rubber products not
covered elsewhere^

U.S. EPA (2020a)

Page 28 of 124


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Life Cycle Stage"

Category''

Subcategory'

References





Toys, playground, and sporting
equipment6'

EP A-HG-GPPT -
2018-0443-0004

Paints and coatings

Paints and coatings^

U.S. EPA. (2020a)

Other

Animal grooming products

Warren London

Disposal

Disposal





a 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.

b These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly
represent conditions of use of D4 in industrial and/or commercial settings.
c These subcategories reflect more specific conditions of use of D4.
d Circumstances on which SEHSC requested that EPA conduct a risk evaluation of D4.

In the final scope, EPA has added the following changes to conditions of use due to additional information from
stakeholder outreach, public comments, and further research:

-	Processing aid (e.g., component in an antifoaming agent);

-	Industrial use in general aircraft maintenance; and

-	Commercial use in laundry and dishwashing products.

2.2.2 Activities Excluded from the Scope of the Risk Evaluation

TSCA section 6(b)(4)(D) requires EPA to identify the hazards, exposures, conditions of use, and the
PESS the Administrator expects to consider in a risk evaluation. TSCA section 3(4) also grants EPA
discretion to determine the circumstances that are appropriately considered to be conditions of use for a
particular chemical substance.4 As a result, EPA does not plan to include in this scope or in the risk
evaluation activities described below that the Agency does not consider to be conditions of use.

4 Chemical substance means any organic or inorganic substance of a particular molecular identity, including any combination
of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature, and any element or
uncombined radical. Chemical substance does not include (1) any mixture; (2) any pesticide (as defined in the Federal
Insecticide, Fungicide, and Rodenticide Act) when manufactured, processed, or distributed in commerce for use as a
pesticide; (3) tobacco or any tobacco product; (4) any source material, special nuclear material, or byproduct material (as
such terms are defined in the Atomic Energy Act of 1954 and regulations issued under such Act); (5) any article the sale of
which is subject to the tax imposed by section 4181 of the Internal Revenue Code of 1954 (determined without regard to any
exemptions from such tax provided by section 4182 or 4221 or any other provision of such Code); and (6) any food, food
additive, drug, cosmetic, or device (as such terms are defined in section 201 of the Federal Food, Drug, and Cosmetic Act)
when manufactured, processed, or distributed in commerce for use as a food, food additive, drug, cosmetic, or device (TSCA
section 3(2)).

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TSCA section 3(2) also excludes from the definition of "chemical substance" "any food, food additive,
drug, cosmetic, or device (as such terms are defined in section 201 of the Federal Food, Drug, and
Cosmetic Act [21 U.S.C. 321]) when manufactured, processed, or distributed in commerce for use as a
food, food additive, drug, cosmetic, or device" as well as "any pesticide (as defined in the Federal
Insecticide, Fungicide, and Rodenticide Act [7 U.S.C. 136 et seq.]) when manufactured, processed, or
distributed in commerce for use as a pesticide." EPA has determined that the following uses of D4 are
non-TSCA uses:

	The Food and Drug Administration lists D4 as an optional substance to be used in food
packaging materials. Food packaging materials meet the definition for a "food additive"
described in section 201 of the FFDCA, 21 U.S.C. 321. Therefore, the use of D4 in food
packaging materials is excluded from the definition of "chemical substance" in TSCA section
3(2)(B)(vi) and is not included in Table 2-2. Activities and releases associated with the use of
such food packaging materials are therefore not "conditions of use" (defined as circumstances
associated with "a chemical substance," TSCA section 3(4)) and will not be evaluated during
risk evaluation.

	EPA determined that D4 is used in dental bonding agents and breast implants which meets the
definition of "device" under section 201 of the FFDCA, 21 U.S.C. 321. Therefore, these uses are
excluded from the definition of "chemical substance" in TSCA section 3(2)(B)(vi) and are not
included in Table 2-2. Activities and releases associated with the use of such medical devices are
therefore not "conditions of use" (defined as circumstances associated with "a chemical
substance," TSCA section 3(4)) and will not be evaluated during risk evaluation.

	EPA determined that D4 is used in personal care products, many of which meet the definition of
"cosmetics" under section 201 of the FFDCA, 21 U.S.C. 321. Therefore, these uses are excluded
from the definition of "chemical substance" in TSCA section 3(2)(B)(vi) and are not included in
Table 2-2. Activities and releases associated with the use of such personal care products are
therefore not "conditions of use" (defined as circumstances associated with "a chemical
substance," TSCA section 3(4)) and will not be evaluated during risk evaluation.

	EPA determined that D4 is used in the over-the-counter medication that meets the definition of a
"drug" in section 201 of the FFDCA, 21 U.S.C. 321. Therefore, the uses are excluded from the
definition of "chemical substance" in TSCA section 3(2)(B)(vi) and are not included in Table
2-2. Activities and releases associated with the use of medical devices are not "conditions of use"
(defined as circumstances associated with "a chemical substance," TSCA section 3(4)) and will
not be evaluated during risk evaluation.

As described in the preamble to the Risk Evaluation Rule (see Procedures for Chemical Risk Evaluation
Under the Amended Toxic Substances Control Act, 33726 Fed. Reg. 33735 (July 20, 2017), EPA may
consider potential risk from non-TSCA uses in evaluating whether a chemical substance presents an
unreasonable risk. Although EPA would not regulate non-TSCA uses, consideration of the potential
exposures from non-TSCA uses may help inform the Agency's risk determination for the exposures
from uses that are covered under TSCA (e.g., as background exposures that would be accounted for
should EPA decide to evaluate aggregate exposures).

2.2.3 Production Volume

As reported to EPA during the 2016 CDR reporting period and described here as a range to protect
production volumes that were claimed as confidential business information (CBI), total production
volume of D4 in 2015 was between 750 million and 1 billion pounds (	20a). EPA plans to

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include more recent production volume information from the 2020 CDR reporting period in the risk
evaluation to support the exposure assessment.

2.2.4 Overview of Conditions of Use and Life Cycle Diagram

Figure 2-11 provides the life cycle diagram for D4. The life cycle diagram is a graphical representation
of the various life stages of the industrial, commercial, and consumer use categories included within the
scope of the risk evaluation. The information in the life cycle diagram is grouped according to the CDR
processing codes and use categories (including functional use codes for industrial uses and product
categories for commercial and consumer uses). Appendix E contains additional descriptions (e.g.,
process descriptions, worker activities, process flow diagrams) for each manufacture, processing,
distribution in commerce, use, and disposal category.

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MFG/IMPORT

PROCESSING

INDUSTRIAL, COMMERCIAL, CONSUMER USES

RELEASES and WASTE DISPOSAL

Manufacture
(Including Import)

(750.000.000-<1B
lb)

Processing as a Reactant

(Adhesives and sealant chemicals, all other
basic inorganic chemical mfg, all other
basic organic chemical mfg, all other
chemical and pdt and preparation mfg,
plastic material and resin mfg, synthetic
rubber mfg)

Repackaging

4

Incorporation into Formulation,
Mixture, or Reaction Product

(All other basic inorganic chem mfg, all
other chem pdt and preparation mfg,
asphalt paving, roofing and coating
materials mfg, computer and electronic pdt
mfg, cyclic crude and intermediate mfg,
electrical equipment, appliance, and
component mfg, misc. mfg, paint and
coating mfg, antifoaming agent rubber pdt
mfg, synthetic rubber mfg.

Recycling

T

Other Uses1
(Aircraft Maintenance)

Adhesives and Sealants1'2

Automotiv e Care Products1,5

Furnishing, Cleaning, Treatment/Care
Products1,2

Ink, Toner and Colorant Products1

Laboratory Chemicals1

Paints and Coatings1'

Plastic and Rubber Products not Covered
Elsewhere1,1

Packaging, Paper, Plastic, Hobby
Products 2

Animal Grooming Products1,2

Manufacture (Including Import)
Processing

Uses:

1.	Industrial and'or commercial

2.	Consumer

Figure 2-11. D4 Life Cycle Diagram

Distribution in commerce is not explicitly included in LCD. For the purposes of the risk evaluation, distribution in commerce is the transportation
associated with moving chemical substances in commerce. Unloading and loading activities are associated with other conditions of use.

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2.3 Exposures

For TSCA exposure assessments, EPA plans to analyze human and environmental exposures and
releases to the environment resulting from the conditions of use within the scope of the risk evaluation
of D4. In this section, the physical and chemical properties, environmental fate and transport properties,
and releases to the environment are described in addition to potential human and environmental
exposures from TSCA conditions of use and from other possible or known sources. Release pathways
and routes will be described in Section 2.6 to characterize the relationship or connection between the
conditions of use of the chemical and the exposure to human receptors, including PESS, and
environmental receptors. EPA plans to consider, where relevant, the duration, intensity (concentration),
frequency, and number of exposures in characterizing exposures to D4.

2.3.1 Physical and Chemical Properties

Consideration of physical and chemical properties is essential for a thorough understanding or prediction
of environmental fate {i.e., transport and transformation) and the eventual environmental concentrations.
It can also inform the hazard assessment. Table 2-3 summarizes the physical and chemical property
values preliminarily selected for use in the risk evaluation from among the range of reported values
collected as of January 2021. This table may be updated as EPA continues to evaluate and integrate
additional information through systematic review methods. EPA plans to use the physical and chemical
characteristics identified through systematic review and provided in the SEHSC submission (Docket ID:
EPA-HQ-QPPT-2018-0443). Figure 2-12 summarizes the distribution of reported values for eight
physical and chemical properties routinely used in existing chemical risk evaluations. Appendix B
presents summary statistics for reported physical and chemical property values. All physical and
chemical property values that were extracted and evaluated as of July 2021 are presented in the
supplemental file Data Extraction and Data Evaluation Tables for Physical and Chemical Property
Studies.

Table 2-3. Physical and Chemical Properties for D4

Property or Endpoint

Value"

Reference

Data Quality
Rating

Molecular formula

C8H2404Si4

NA

NA

Molecular weight

296.61 g/mol

NA

NA

Physical state

Smooth, viscous liquid

NLM (2020)

High

Physical properties

Colorless liquid

(RSC. 2020)

High

Melting point

17.5 C

(O'NeiL 2013)

High

Boiling point

-J

O

o

(O'NeiL 2013)

High

Density

0.95603 g/cm3 at 20 C

(Zhang et al. 2015)

High

Vapor pressure

1.05 mm Hg at 25 C

NLM (2020)

High

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Property or Endpoint

Value"

Reference

Data Quality
Rating

Vapor density

No data identified

-

-

Water solubility

0.056 mg/L at 23 C

(Varaorath et al 1996)

High

Log Octanol/water
partition coefficient
(Log Kow)

6.59 at 5.7 C
6.98 at 21.7 C
7.13 at 34.8 C

Xu and Krooscott (2012)

and Xu and Krooscott
{

High

Henry's Law constant
(atm m3/mol)

I.4	at 5.7 C

II.8	at 21.7 C
31.1 at 34.8 C

Xu and Krooscott (2012)
and Xu and Krooscott
{

High

Flash point

55 C

NLM (2020)

High

Auto flammability

No data identified

-

-

Viscosity

2.30 cP at 25 C

NLM (2020)

High

Refractive index

1.39674 at 20 C

(Zhang et al. 2015)

High

Dielectric constant

2.4-2.405 at 20 C

(Elsevier. 2019)

High

a Measured unless otherwise noted.

Figure 2-12 displays a summary of the data collected by EPA during its independent systematic review
process as of January 2021 for eight physical and chemical values routinely used in TSCA existing
chemical risk evaluations. The box and whisker plots for each endpoint illustrate the mean (average,
indicated by the blue diamond) and the 10th, 25th, 50th (median), 75th, and 90th percentiles. All
individual data points are indicated by black squares, and value preliminarily selected for use in the risk
evaluation is overlaid (indicated by the orange circle) to provide context for where it lies within the
distribution of the data set. The number of unique primary data sources is indicated below each box and
whisker plot. If multiple sources presented equivalent values and cited the same primary source, only
one of those was included in the statistical calculations. As a result, the number of sources listed in
Figure 2-12 may differ from the total number of data sources presented in Figure 2-2.

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Boiling Point
(n = 16)

 17.5-

17.0-

Melting Point
(n = 20)

! 0.9

Flash Point

-------
tetramethyldisiloxanediol (CASRN 118-15-6), DMSD (CASRN 1066-42-8), and orthosilicic acid
(CASRN 10193-36-9) in the draft scope document. Physical and chemical property values for these
substances, except orthosilicic acid, were extracted and evaluated as of July 2021 and are presented in
the supplemental file Data Extraction and Data Evaluation Tables for Physical and Chemical Property
Studies for D4 Degradants. However, EPA recognizes that only DMSD has been detected in
environmental samples and that orthosilicic acid (CASRN 10193-36-9) is a macroelement originating
from silicate minerals in soil and marine environments. EPA received information on the physical and
chemical properties along with environmental fate characteristics only for DMSD (Docket No. EPA-
HQ-OPPT-2018-0443-0028) This information will be analyzed as described in Section 2.7.1.

2.3.3	Releases to the Environment

Releases to the environment from conditions of use are a component of potential exposure and may be
derived from reported data that are obtained through direct measurement, calculations based on
empirical data and/or assumptions and models.

D4 is not reported to the Toxics Release Inventory (TRI). There may be releases of D4 from industrial
sites to wastewater treatment plants (WWTP), surface water, air, and landfills. Articles that contain D4
may release D4 to the environment during use or through recycling and disposal. EPA plans to review
these data in conducting the exposure assessment component of the risk evaluation for D4.

2.3.4	Environmental Exposures

The manufacturing, processing, distribution, use, and disposal of D4 can result in releases to the
environment and exposure to aquatic and terrestrial receptors (biota). Environmental exposures are
informed by releases into the environment, overall persistence, degradation, bioaccumulation within the
environment, and partitioning across different media. Concentrations of chemical substances in biota
provide evidence of exposure. EPA plans to review reasonably available environmental monitoring data
for D4.

As described in Section 2.3.2, EPA identified studies reporting that D4 degrades into DMSD in water,
soil, and sediment via different intermediate degradants under specific field and laboratory conditions.
Concentrations of DMSD in water, soil, and sediment could provide information for environmental
exposure to D4 degradants. In the draft scope document, EPA requested information from the public on
the environmental concentration of DMSD and other degradation products of D4 in water, soil, and
sediment. The Agency received some information from the public on the presence of DMSD in these
environmental media, and EPA will evaluate this information according to the systematic review process
described in EPA's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (December 20, 2021) (Docket No. EPA-H.O-OPPT-2021 -0414).

2.3.5	Occupational Exposures

EPA plans to evaluate worker activities where there is a potential for exposure under the various
conditions of use (distribution in commerce, manufacturing, processing, industrial/commercial uses, and
disposal) described in Section 2.2. In addition, EPA plans to evaluate exposure to ONUs, (i.e., workers
who do not directly handle the chemical but perform work in an area where the chemical is present).
EPA will not make risk determinations based on assumptions about the use of personal protective
equipment (PPE) or control technologies. However, EPA plans to develop exposure scenarios with and
without the use of PPE and engineering controls to inform any potential risk management measures
required for workers or ONUs.

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Examples of worker activities associated with the conditions of use within the scope of the risk
evaluation for D4 that EPA might analyze include, but are not limited to

	Unloading and transferring D4 to and from storage containers to process vessels;

	Handling, transporting, and disposing of waste containing D4;

	Cleaning and maintaining equipment;

	Sampling chemicals, formulations, or products containing D4 for quality control;

	Repackaging chemicals, formulations, or products containing D4; and

	Perform other work activities in or near areas where D4 is used.

D4 is a liquid at room temperature and, as stated in Table 2-3, has a vapor pressure of 1.05 mm Hg at 25
C. Because the chemical is semi-volatile, EPA plans to analyze inhalation exposure to vapor for
workers and ONUs. EPA also plans to analyze inhalation exposure for workers and ONUs in
occupational scenarios where D4 or products containing D4 are applied via spray application methods or
are handled as a dry powder. D4 does not have occupational exposure limits established by the
Occupational Health and Safety Administration (OSHA), the National Institute for Occupational Safety
and Health (NIOSH), or the American Conference of Governmental Industrial Hygienists.

Based on the conditions of use, EPA plans to analyze worker exposure to liquids and/or solids via the
dermal route. EPA plans to analyze dermal exposure for workers and ONUs to dust or mist that deposit
on surfaces.

During public comment, EPA requested information from the public about the following two
occupational exposure scenarios that are among the scenarios that EPA plans to evaluate: dermal
exposure of workers who handle articles containing D4 resulting from migration of D4 from these
articles; and worker and ONU inhalation exposure at landfills to D4 vapor and dust containing D4. EPA
did not receive any information during the public comment period related to these occupational exposure
scenarios.

Workers and ONUs may inadvertently ingest inhaled particles that deposit in the upper respiratory tract.
In addition, workers may transfer chemicals from their hands to their mouths. The frequency and
significance of this exposure route are dependent on several factors, including the physical and chemical
properties of the substance during worker activities, the visibility of the chemicals on the hands while
working, workplace training and practices, and personal hygieneall of which is difficult to predict
("Cherrie et at.. 2006). EPA plans to consider the relevance of this exposure route on a case-by-case
basis, taking into consideration the aforementioned factors and any reasonably available information,
and may assess oral exposure for workers for certain conditions of use and worker activities where
warranted. For certain conditions of use of D4, EPA plans to consider inhalation exposure to
dust/particulates for workers and ONUs. As inhalation exposure to dust/particulates may occur, EPA
plans to consider potential exposure for particulates that deposit in the upper respiratory tract from
inhalation exposure and may be ingested via the oral route.

2.3.6 Consumer Exposures

Information contained in the submission requesting the risk evaluation for D4 along with CDR reporting
and other sources indicate the presence of D4 in a number of consumer products and articles including:
adhesives and sealants; automotive care products; furnishing, cleaning, treatment/care products; paints
and coatings; and plastic and rubber products not covered elsewhere (see Section 2.6.1 and Figure 2-14)
(Docket ID: EPA-HO-OPI	) (	320a). These uses can result in exposures to

consumers and bystanders (non-product users that are incidentally exposed to the product).

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Based on reasonably available information on consumer conditions of use, inhalation of D4 is possible
through either inhalation of vapor/mist during product usage or indoor air/dust. Oral exposure of D4 is
possible through ingestion through product use via transfer from hand to mouth, mouthing of articles,
and incidental ingestion of dust or vapor/mist containing D4. Dermal exposure may occur via contact
with dust, vapor, or mist deposition onto the skin, via direct liquid contact during use, or direct dermal
contact of articles containing D4. Based on these potential sources and pathways of exposure, EPA plans
to analyze oral, dermal, and inhalation exposures to consumers and inhalation exposures to bystanders
that may result from the conditions of use of D4 as described in Section 2.6.1 and the analysis plan.

2.3.7 General Population Exposures

Releases of D4 from certain conditions of use such as, but not limited to, manufacturing, processing, or
disposal activities may result in general population exposures. General population may be exposed via
oral, dermal, or inhalation routes. The SEHSC submission (Docket ID: EPA-HQ-OPPT-2018-0443)
considered the following exposure pathways for general population (1) inhalation from ambient and
indoor air; (2) ingestion via consumption of food items grown on soil containing D4, via drinking water,
consumption of fish exposed to surface water or sediments containing D4, subsistence fishing, and
human milk; and (3) for dermal absorption from use of products containing D4. The SEHSC submission
exposure assessment of the general population was based on Gentry et al. (2017) and EC/HC (2008). In
addition, because preliminary information suggests that D4 may bioaccumulate in fish, EPA plans to
review the information available for ingestion via consumption of fish and subsequent bioaccumulation
to the general population. EPA plans to review the information contained in the SEHSC submission
requesting the risk evaluation for D4 (Docket ID: EPA-HQ-QPPT-2018-0443) as well as other
reasonably available information for the presence of D4 in environmental media relevant to general
population exposure.

EPA identified studies reporting that D4 degrades into DMSD in water, soil, and sediment via different
intermediate degradants under specific field and laboratory conditions (see Section 2.3.2).

Concentrations of DMSD in soil, surface water, groundwater, or drinking water could provide
information for general population exposure to D4 degradants. In the draft scope document, EPA
requested additional information from the public on the concentration of DMSD and other degradation
products in these environmental media. EPA received some information from the public only for DMSD
on its presence in environmental media and will evaluate this information according to the Agency's
systematic review process described in EPA's Draft Systematic Review Protocol Supporting TSCA Risk
Evaluations for Chemical Substances (December 20, 2021) (Docket No. EP A-HQ-OPPT-2021 -0414).

Human biomonitoring data exist, including three studies that collected and measured D4 concentrations
in plasma. The 2019 SEHSC submission (Docket ID: EP A-HQ-OPPT-2018-0443) references the
following biomonitoring studies. Xu et al. (2012) reported D4 plasma concentrations ranged from 4.56
to 57.8 ng/g for residents near a siloxane manufacturing facility. Hanssen et al. ) reported D4
plasma concentrations ranged from 12.7 to 20.93 ng/mL for postmenopausal women and 1.70 to 2.69
ng/mL for pregnant women. ime et al. (2015) reported a maximum D4 concentration in blood of
0.73 |ig/L for adults (21 females and males aged 20 to 68 years).

The presence in environmental media and biomonitoring data suggest that general population exposures
are occurring. EPA plans to review reasonably available information related to general population
exposures in the risk evaluation. The general population pathways in the scope of this evaluation are
described in Section 2.6.3.

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2.4 Hazards (Effects)

2.4.1	Environmental Hazards

EPA considered information in the SEHSC submission requesting the risk evaluation for D4 (Docket
ID: EPA-HQ-QPPT-2018-0443) and all other reasonably available information (e.g., federal and
international government chemical assessments). Using automated techniques during the data screening
phase of systematic review, EPA identified the following potential hazard effects for aquatic and
terrestrial organisms, along with related information that may be considered for the risk evaluation (as
explained in Appendix A): ADME, developmental, gastrointestinal, mortality, neurological, nutritional
and metabolic, reproductive, and respiratory (Figure 2-10). A summary of references identified during
the screening step of systematic review is included in the interactive literature inventory trees (Figure
2-9). As EPA continues to evaluate reasonably available and relevant hazard information identified
through systematic review, EPA may update the list of potential hazard effects to be analyzed in the risk
evaluation.

As described in Section 2.3.2, EPA identified studies reporting that D4 degrades into DMSD in water,
soil, and sediment via different intermediate degradants under various conditions. Concentrations of
DMSD in water, soil, and sediment could provide information for environmental exposure assessment to
D4 degradants. In the draft scope document, EPA requested information from the public on the toxicity
of DMSD and the other degradation products of D4. EPA received toxicity information only for DMSD
and will evaluate this information according to EPA's systematic review process described in EPA's
Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances
(December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414).

2.4.2	Human Health Hazards

EPA considered information in the SEHSC submission requesting the risk evaluation for D4 (Docket
ID: EPA-HQ-QPPT-2018-0443) and all other reasonably available information (e.g., federal and
international government chemical assessments). Using automated techniques during the data screening
phase of systematic review, EPA identified the following potential human health hazards, along with
related information that may be considered for the risk evaluation (as explained in Appendix A):

ADME, cancer, endocrine, gastrointestinal, hematological and immune, hepatic, mortality, neurological,
nutritional and metabolic, ocular and sensory, renal, reproductive, developmental, respiratory, skin and
connective tissue (Figure 2-10). A summary of references identified during the screening step of
systematic review is included in the interactive literature inventory trees (Figure 2-9). As EPA continues
to evaluate reasonably available and relevant hazard information identified through systematic review,
the Agency may update the list of potential hazard effects to be analyzed in the risk evaluation.

As described in Section 2.3.2, EPA identified studies reporting that D4 degrades into DMSD in water,
soil, and sediment via different intermediate degradants under various conditions. Concentrations of
DMSD in water, soil, and sediment could provide information for the general population exposure
assessment to D4 degradants. In the draft scope document, EPA requested information from the public
on the toxicity of DMSD and the other degradation products of D4. EPA received toxicity information
only for DMSD and will evaluate this information according to the systematic review process described
in the Agency's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (December 20, 2021) (Docket No. EPA-HO-OPPT-2021 -0414).

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2.5 Potentially Exposed or Susceptible Subpopulations

TSCA section 6(b)(4) requires EPA to determine whether a chemical substance or category of chemical
substances presents an unreasonable risk to "a potentially exposed or susceptible subpopulation
identified as relevant to the risk evaluation." TSCA section 3(12) states that "the term 'potentially
exposed or susceptible subpopulation' means a group of individuals within the general population
identified by the Administrator who, due to either greater susceptibility or greater exposure, may be at
greater risk than the general population for adverse health effects from exposure to a chemical substance
or mixture, such as children, women who are or may become pregnant, workers, or the elderly." General
population is "the total of individuals inhabiting an area or making up a whole group" and refers here to
the U.S. general population (	).

EPA plans to consider the following groups as PESS based on CDR information and studies reporting
developmental and reproductive effects: children, women of reproductive age (e.g., women who are or
may become pregnant), workers, ONUs, consumers, bystanders, fenceline communities, and indigenous,
native populations as PESS in the risk evaluation. Other PESS may be identified based on reasonably
available information.

EPA plans to include and address environmental justice6 considerations by evaluating reasonably
available information on factors that may make population groups of concern more vulnerable to
adverse effects (e.g., unique pathways; cumulative exposure from multiple stressors; behavioral,
biological, or environmental factors that increase susceptibility); identifying unique considerations for
subsistence populations when relevant; and following best practices from the Agency's Technical
Guidance for Assessing Environmental Justice in Regulatory Analysis (	). EPA will

consider different dimensions of susceptibility when selecting critical endpoints, point(s) of departure
(PODs), determination of uncertainty factors, and margins of exposure.

In developing exposure scenarios, EPA plans to analyze reasonably available information in order to
determine whether some human receptor groups may be exposed via exposure pathways that may be
distinct to a particular subpopulation or life stage (e.g., reproductive age females who may be or become
pregnant, lactating women, infants, toddlers, children at various developmental stages in life, and
elderly) and whether some human receptor groups may have higher exposure via identified pathways of
exposure due to unique characteristics (e.g., activities, duration or location of exposure) when compared
with the general population (	006b). Likewise, EPA plans to evaluate reasonably available

human health hazard information in order to determine whether some human receptor groups may have
greater susceptibility than the general population to the chemical's hazard(s). Based on these analyses,
EPA may expand the PESS considered in the risk evaluation.

6 Additional information is available regarding EPA's Office of Environmental Justice.

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2.6 Conceptual Models

In this section, EPA presents the conceptual models describing the identified exposures (pathways and
routes), receptors, and hazards associated with the conditions of use of D4. Pathways and routes of
exposure associated with workers and ONUs are described in Section 2.6.1, and pathways and routes of
exposure associated with consumers are described in Section 2.6.2. Pathways and routes of exposure
associated with environmental releases and wastes are discussed and depicted the conceptual model
shown in Section 2.6.3.

2.6,1 Conceptual Model for Industrial and Commercial Activities and Uses

Figure 2-13 illustrates the conceptual model for the pathways of exposure from industrial and
commercial activities and uses of D4 that EPA plans to include in the risk evaluation. There is potential
for exposures to workers and/or ONUs via inhalation and dermal routes. Dermal exposure to D4 in both
liquid and solid form is expected, as products and formulations containing D4 can be used/transported in
liquid or solid form. EPA plans to evaluate activities resulting in exposures associated with distribution
in commerce (e.g., loading, unloading) throughout the various life cycle stages and conditions of use
(e.g., manufacturing, processing, industrial use, commercial use, disposal) rather than a single
distribution scenario.

Appendix F presents the combinations of exposure pathways, routes, and receptors for each condition of
use identified in Table 2-2 along with supporting rationale for whether EPA plans to evaluate those
combinations.

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INDUSTRIAL AND COMMERCIAL
ACTIVITIES / USES

EXPOSURE PATHWAY

EXPOSURE ROUTE

RECEPTORS

HAZARDS

Manufacturing
(incl. Import)

Processing
Processing as a Readmit
Incorporation into
Formulation, Mixture, or
Reaction Product
Repackaging

Other Uses (Aircraft
Maintenance)

Adhesives and Sealants

Automotive Care Products

Furnishing, Cleaning,
Treatment/Care Products

Ink, Toner and Colorant
Products

Laboratory Chemicals

Paints and Coatings

Plastic and Rubber
Products not Covered
Elsewhere

Animal Grooming
Products

Waste Handling, Treatment
and Disposal

Hazards Potentially

Associated with
Acute and/or Chronic
Exposures

Wastewater, Liquid Wastes, and Solid Wastes
("See Environmental Release Conceptual Model)

Figure 2-13. D4 Conceptual Model for Industrial and Commercial Activities and Uses: Worker and ONU Exposures and Hazards"

The conceptual model presents the exposure pathways, exposure routes, and hazards to human receptors from industrial and commercial activities and uses
of D4.

a Receptors include PESS (see Section 2.5)

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2.6,2 Conceptual Model for Consumer Activities and Uses

The conceptual model in Figure 2-14 presents the exposure pathways, exposure routes, and hazards to
human receptors from consumer activities and uses of D4. EPA expects that consumers and bystanders
may be exposed through use of products or articles containing D4 via oral, dermal, and inhalation
routes. An "article," as defined at 40 CFR 704.3, is distinct from a "product" in that an article is "a
manufactured item:

1.	which is formed to a specific shape or design during manufacture;

2.	which has end use function(s) dependent in whole or in part upon its shape or design during end
use; and

3.	which has either no change of chemical composition during its end use or only those changes of
composition which have no commercial purpose separate from that of the article, and that result
from a chemical reaction that occurs upon end use of other chemical substances, mixtures, or
articles; except that fluids and particles are not considered articles regardless of shape or
design."

Additionally, during use of articles, EPA expects that consumers may also be exposed via direct
dermal contact or mouthing (Figure 2-14). EPA plans to analyze pathways and routes of exposure that
may occur during the varied identified consumer activities and uses. The supporting rationale for
consumer pathways considered for D4 are included in Appendix G.

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CONSUMER ACTTVrnES&	EXPOSURE	EXPOSURE	DrrrDTnot	D.74Dnc

USES	PATHWAY	ROUTE	RECEPTORS	HAZARDS

ARTICLE

Fabric, textile, and leather
products not covered elsewhere

Plastic and rubber products not
covered elsewhere

Toys, Playground, and Sporting
Equipment

PRODUCT

Adhesives and Sealants

Animal Grooming Products

Automotive Care Products

Cleaning and Furnishing Care
Products

Fabric, Textile, and Leather
Products not Covered Elsewhere

Laundry and dishwashing products

Paints and Coatings

Plastic and rubber products not
covered elsewhere

Toys, Playground, and Spoiling
Equipment

Wastewater. Liquid Wastes and
Solid Wastes (See
Environmental Releases
Conceptual Model

Hazards Potentially
Associated with Acute
and/or Chronic
Exposures

Consumer Handling of
Disposal and Waste

Figure 2-14. D4 Conceptual Model for Consumer Activities and Uses: Consumer Exposures and Hazards"

The conceptual model presents the exposure pathways, exposure routes, and hazards to human receptors from consumer activities and uses of D4.
11 Receptors include PESS (see Section 2.5)

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2.6.3 Conceptual Model for Environmental Releases and Wastes: Potential Exposures
and Hazards

In this section, EPA presents the conceptual model describing the identified exposures (pathways and
routes from environmental releases and wastes) and hazards to general population and environmental
receptors associated with the conditions of use of D4 within the scope of the risk evaluation.

The conceptual model in Figure 2-15 presents the potential exposure pathways, exposure routes, and
hazards to general population and environmental receptors from releases and waste streams associated
with industrial, commercial, and consumer uses of D4 within the scope of the risk evaluation. EPA plans
to evaluate exposures to receptors (e.g., general population, aquatic and terrestrial species) that may
occur from releases to air; releases to surface water, as well as indirect releases to drinking water and
groundwater; and releases to land, including releases to landfill, biosolids, and soil. EPA expects the
general population to be exposed to D4 from air emissions via inhalation as well as from surface water,
drinking water, liquid, and solid waste releases; orally via drinking water, fish, and soil ingestion; and
dermally from contact with groundwater, drinking water, and soil. The supporting rationale for general
population and environmental pathways considered for D4 are included in Appendix H.

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RELEASES AND WASTES FROM INDUSTRIAL /
COMMERCIAL / CONSUMER USES

EXPOSURE PATHWAYS

EXPOSURE ROUTES

RECEPTORS

HAZARDS

Industrial Pre-
-~ Treatment or

Figure 2-15. D4 Conceptual Model for Environmental Releases and Wastes: Environmental and General Population Exposures and
Hazards"6

The conceptual model presents the exposure pathways, exposure routes, and hazards to human and environmental receptors from releases and wastes from
industrial, commercial, and consumer uses of D4 that EPA plans to consider in the risk evaluation.

11 Industrial wastewater or liquid wastes may be treated on-site and then released to surface water (direct discharge), or pre-treated and released to publicly owned
treatment works (POTWs) (indirect discharge). For consumer uses, such wastes may be released directly to POTWs. Drinking water will undergo further
treatment in drinking water treatment plant. Groundwater may also be a source of drinking water. Inhalation from drinking water may occur via showering.
h Receptors include PESS (see Section 2.5)

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2.7 Analysis Plan

The analysis plan is based on EPA's knowledge of D4 resulting from the full-text screening of
reasonably available information identified through EPA's literature searches as well as the information
included in the SEHSC submission (see Section 2.1). EPA encourages submission of additional existing
information, such as full study reports or workplace monitoring from industry sources, that may be
relevant to EPA's evaluation of conditions of use, exposures, hazards, and PESS during the risk
evaluation. Targeted supplemental searches during the analysis phase may be necessary to identify
additional reasonably available information (e.g., commercial mixtures) for the risk evaluation of D4.
For any data needs identified during the risk evaluation, EPA may use the Agency's TSCA authorities
under sections 4, 8, or 11, as appropriate.

2.7,1 Physical and Chemical Properties and Environmental Fate

EPA plans to analyze the physical and chemical properties and environmental fate and transport of D4
according to the steps below. EPA will consider all reasonably available information on D4 degradation
products for inclusion in the risk evaluation pending the data evaluation, synthesis, and integration
phases of systematic review.

1)	Review reasonably available measured or estimated physical and chemical properties and
environmental fate endpoint data.

EPA plans to evaluate data and information submitted with the request for risk evaluation and
collected through the systematic review process and public comments about the physical and
chemical properties (Appendix B) and fate endpoints (Appendix C). The Agency plans to
evaluate all sources cited in the analysis plan according to the procedures and metrics described
in EPA's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (December 20, 2021) (Docket No. EPA-HO-Q] 21-0414V Where
experimentally measured values for chemical properties are not reasonably available or of
sufficiently high quality, values will be estimated using chemical parameter estimation models as
appropriate. Model-estimated fate properties will be reviewed for applicability and quality.

2)	Using measured data and/or modeling, determine the influence of physical and chemical
properties and environmental fate endpoints (e.g., persistence, bioaccumulation,
partitioning, transport) on exposure pathways and routes of exposure to human and
environmental receptors.

Measured data and, where necessary, model predictions of physical and chemical properties and
environmental fate endpoints will be used to characterize the persistence and movement of D4
and its degradants within and across environmental media. The fate endpoints of interest include
volatilization, sorption to organic matter in soil and sediments, water solubility, aqueous and
atmospheric photolysis rates, aerobic and anaerobic biodegradation rates, and potential
bioconcentration and bioaccumulation. EPA plans to use these endpoints in exposure
calculations.

3)	Conduct a weight of the scientific evidence evaluation of physical and chemical properties
and environmental fate data, including qualitative and quantitative sources of information.

During the risk evaluation, EPA plans to evaluate and integrate the physical and chemical
property and environmental fate evidence identified in the literature inventory and in the SEHSC
submission using revised systematic review methods described in EPA's Draft Systematic
Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances (December 20,
2021) (Docket No. EPA-HO-OPF	).

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2.7.2 Exposure

EPA plans to analyze exposure levels for indoor dust, indoor air, ambient air, surface water, drinking
water, groundwater, sediment, soil, biosolids, fish ingestion, aquatic biota, and terrestrial biota
associated to exposure to D4. Based on their physical and chemical properties, expected sources, and
transport and transformation within the outdoor and indoor environment, D4 and degradation products
are more likely to be present in some of these media and less likely to be present in others. EPA has not
yet determined the exposure levels in these media. Exposure level(s) can be characterized using a
combination of reasonably available monitoring data and estimated exposure levels from modeling
approaches. Exposure scenarios are combinations of sources (uses), exposure pathways, and exposed
receptors. D4 degradation products can be present in outdoor and indoor environments and their
consideration in exposure scenarios and analysis depends on the available information. Draft exposure
scenarios corresponding to various conditions of use for D4 are presented in Appendix F, Appendix G,
and Appendix H. EPA will consider all reasonably available information on D4 degradation products for
inclusion in the risk evaluation pending the data evaluation, synthesis, and integration phases of
systematic review.

2.7,2.1 Environmental Releases

EPA plans to analyze releases to environmental media as follows:

1)	Review reasonably available published literature and other reasonably available
information on processes and activities associated with the conditions of use to analyze the
types of releases and wastes generated.

EPA has reviewed some sources containing information on processes and activities resulting in
releases, and the information found is described in Appendix E. EPA plans to review additional
data sources identified. Potential sources of environmental release data are summarized in Table
2-4 below.

Table 2-4. Categories and Sources of Environmental Release Data	

EPA Generic Scenarios	

Organisation for Economic Co-operation and Development (OECD) Emission Scenario

Documents	

Environment Canada Screening Assessment for the Challenge,

Octamethylcyclotetrasiloxane (D4), 2008	

SEHSC D4 Environmental Testing Study Plan, Enforceable Consent Agreement, 2016,

(Docket No. EPA-} > >i'PT-2Q [2-Q2091 	

SEHSC submission (Docket No. EPA-HO-O:	3443-00041	

2)	Review reasonably available chemical-specific release data, including measured or
estimated release data (e.g., data from risk assessments by other environmental agencies).

EPA plans to evaluate additional reasonably available information during development of the
risk evaluation. EPA plans to match identified data to applicable conditions of use and identify
conditions of use for which data are limited. EPA plans to augment and/or supplement data
through the use of models and potential surrogate data where appropriate.

Additionally, for conditions of use where no measured data on releases are reasonably available,
and it may not be appropriate to use TSCA sections 4, 8, or 11 to collect such information (see,
e.g., the definition of "reasonably available information" in 40 CFR 702.33), EPA may use a
variety of methods including release estimation approaches and assumptions in the Chemical
Screening Tool for Exposures and Environmental Releases (ChemSTEER) (	2015a).

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3)	Review reasonably available measured or estimated release data for surrogate chemicals
that have similar uses and physical properties.

EPA plans to review literature sources identified, and if surrogate data are found, these data will
be matched to applicable conditions of use to potentially augment and/or supplement existing
data. Measured or estimated release data for other siloxanes may be considered as surrogates for
D4.

4)	Review reasonably available data that may be used in developing, adapting, or applying
exposure models to the particular risk evaluation.

This item will be performed after completion of #2 and #3 above. EPA plans to evaluate relevant
data to determine whether the data can be used to develop, adapt, or apply models for specific
conditions of use (and corresponding release scenarios). EPA has identified information from
various EPA statutes and sources (including, for example, regulatory limits, reporting thresholds
or disposal requirements) that may be relevant to release estimation and environmental
exposures. EPA plans to consider relevant regulatory requirements in estimating releases during
risk evaluation.

5)	Review and determine applicability of OECD Emission Scenario Documents (ESDs) and
EPA Generic Scenarios (GSs) to estimation of environmental releases.

EPA has identified potentially relevant OECD Emission Scenario Documents (ESDs) and EPA.
Generic Scenarios (GSs) that correspond to some conditions of usefor example, the	D

on Use of Adhesives (OECD. 2015). the 2009 ESP on Adhesr nutation (OECD. 2009a).
the 2004 ESP on Rubber Additives (OECD. 2004). and the 2011 ESP on Radiation Curable
Coating. Inks and Adhesives (OE<	)may be useful to assess potential releases. EPA

plans to critically review these ESDs and GSs to determine their applicability to the conditions of
use assessed.

If ESDs and GSs are not available, other methods may be considered. EPA may also perform
supplemental targeted searches of peer-reviewed or gray literature for applicable models and
associated parameters that EPA may use to estimate releases for certain conditions of use.
Additionally, for conditions of use where no measured data on releases are reasonably available,
EPA may use a variety of methods including the application of default assumptions such as
standard loss fractions associated with drum cleaning (3 percent) or single process vessel
cleanout (1 percent).

6)	Map or group each condition of use to a release assessment scenario(s).

EPA has completed initial mapping of release scenarios to relevant conditions of use as shown in
Appendix F. The Agency plans to refine the mapping/grouping of release scenarios based on
factors (e.g., process equipment and handling, magnitude of production volume used,
exposure/release sources) corresponding to conditions of use using reasonably available
information. EPA may perform supplemental targeted searches of peer-reviewed or gray
literature to better understand certain conditions of use to further develop these release scenarios.

7)	Evaluate the weight of the scientific evidence of environmental release data.

During risk evaluation, EPA plans to evaluate and integrate the environmental release evidence
identified in the literature inventory using revised systematic review methods described in EPA's
Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances
(December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414). The Agency plans to integrate
the data using systematic review methods to assemble the relevant data, evaluate the data for

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quality and relevance, including strengths and limitations, followed by synthesis and integration
of the evidence.

2.7.2.2 Environmental Exposures

EPA plans to analyze the following in developing its environmental exposure assessment of D4:

1)	Review reasonably available environmental and biological monitoring data for all media
relevant to environmental exposure.

For D4, environmental media that EPA plans to analyze are sediment, soil, biosolids, air,
drinking water, groundwater, and surface water.

2)	Review reasonably available information on releases to determine how modeled estimates
of concentrations near industrial point sources compare with reasonably available
monitoring data.

EPA plans to analyze and consider reasonably available environmental exposure models that
meet the scientific standards under TSCA section 26(h) and that estimate air, surface water,
groundwater, sediment, biosolids, and soil concentrations alongside reasonably available air,
surface water, groundwater, sediment, and soil monitoring data to characterize environmental
exposures. Modeling approaches to estimate concentrations in air, surface water, sediment,
biosolids, and soil may generally include the following inputs: direct release into air,
groundwater, surface water, sediment, or soil; indirect release into air, groundwater, surface
water, sediment, or soil (i.e., air deposition); fate and transport (partitioning within media); and
characteristics of the environment (e.g., river flow, volume of lake, meteorological data).

3)	Determine applicability of existing additional contextualizing information for any
monitored data or modeled estimates during risk evaluation.

EPA plans to evaluate any studies that relate levels of D4 in the environment or biota with
specific sources or groups of sources. The Agency plans to review and characterize monitoring
data or modeled estimates to determine how representative they are of ongoing use patterns.

4)	Group each condition(s) of use to environmental assessment scenario(s).

EPA plans to refine and finalize exposure scenarios for environmental receptors by considering
combinations of sources (use descriptors), exposure pathways including routes, and populations
exposed. For D4, the following are noteworthy considerations in constructing exposure scenarios
for environmental receptors:

-	Estimates of concentrations in air, groundwater, surface water , sediment, and soil near
industrial point sources based on reasonably available monitoring data;

-	Consider the following modeling inputs: release into the media of interest, fate and
transport, and characteristics of the environment;

-	Reasonably available biomonitoring data. Monitoring data could be used to compare with
species or taxa-specific toxicological benchmarks;

-	Applicability of existing additional contextualizing information for any monitored data or
modeled estimates during risk evaluation. Review and characterize the spatial and
temporal variability, to the extent that data are reasonably available, and characterize
exposed aquatic and terrestrial populations; and

-	Weight of the scientific evidence of environmental occurrence data and modeled
estimates.

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5) Evaluate the weight of the scientific evidence of environmental occurrence data and
modeled estimates.

During risk evaluation, EPA plans to evaluate and integrate the exposure evidence identified in
the literature inventory using revised systematic review methods described in the Agency's Draft
Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances
(December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414).

2.7.2,3 Occupational Exposures

EPA plans to analyze both worker and ONU exposures as follows:

1) Review reasonably available exposure monitoring data for specific condition(s) of use.

EPA plans to review exposure data including workplace monitoring data collected by
government agencies such as OSHA and NIOSH, as well as monitoring data found in published
literature, and any relevant information provided in the SEHSC submission. These workplace
monitoring data include personal exposure monitoring data (direct exposures) and area
monitoring data (indirect exposures).

EPA has also identified additional data sources that may contain relevant monitoring data for the
various conditions of use. EPA plans to review these sources (identified in Table 2-5) and extract
relevant data for consideration and analysis during risk evaluation.

Table 2-5. Potential Sources of Occupational Exposure Data	

Environment Canada Screening Assessment for the Challenge,

Octamethylcyclotetrasiloxane (D4), 2008	

Gentry at al., 2017. A Global Human Health Risk Assessment for

Octamethylcyclotetrasiloxane (D4).	

EPA-H.O-OPPT-2018-0443-0004	

2)	Review reasonably available exposure data for surrogate chemicals that have uses,
volatility, and physical and chemical properties similar to D4.

EPA plans to review literature sources submitted in the SEHSC submission and identified
through systematic review, and if surrogate data are found, these data will be matched to
applicable conditions of use for potentially filling data gaps.

3)	For conditions of use where data are limited or not reasonably available, review existing
exposure models that may be applicable in estimating exposure levels.

EPA has identified potentially relevant OECD ESDs and EPA GSs corresponding to some
conditions of use. For example, the . ' < < v D on the Use of Adhesive (> v v < > < s ) and the
201 I \ 'SD on Radiation Curable Coating. Inks and Adhesives (OEt 1 * _  l l) are some of the
ESDs and GSs that EPA may use to estimate occupational exposures. EPA plans to critically
review these ESDs and GSs to determine their applicability to the conditions of use assessed.
EPA may conduct or perform supplemental targeted searches of peer-reviewed or gray literature
to understand those conditions of use, which may inform identification of exposure scenarios.
EPA may also need to perform targeted supplemental searches to identify applicable models that
EPA may use to estimate exposures for certain conditions of use.

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4)	Review reasonably available data that may be used in developing, adapting, or applying
exposure models to a particular risk evaluation scenario.

This step will be performed after #2 and #3 are completed. Based on information developed from
#2 and #3, EPA plans to evaluate relevant data to determine whether the data can be used to
develop, adapt, or apply models for specific conditions of use (and corresponding exposure
scenarios). EPA may utilize existing, peer-reviewed exposure models developed by the Agency,
other government agencies, or reasonably available in the scientific literature, or EPA may elect
to develop additional models to assess specific condition(s) of use. Inhalation exposure models
may be simple box models or two-zone (near-field/far-field) models. In two-zone models, the
near-field exposure represents potential inhalation exposures to workers, and the far-field
exposure represents potential inhalation exposures to ONUs.

5)	Consider and incorporate applicable engineering controls and/or PPE into exposure
scenarios.

In the risk evaluation, EPA plans to examine the effects of engineering controls and PPE on
occupational exposures to support any potential risk management in the event of an unreasonable
risk determination. OSHA recommends employers utilize the hierarchy of controls to address
hazardous exposures in the workplace. The hierarchy of controls strategy outlines, in descending
order of priority, the use of elimination, substitution, engineering controls, administrative
controls, and, lastly, PPE. EPA plans to identify the engineering controls and PPE relevant to
occupational exposure scenarios based on reasonably available information on control
technology and effectiveness. Furthermore, to better inform any potential risk management, EPA
plans to assess in the risk evaluation worker exposure pre- and post-implementation of
engineering controls (e.g., local exhaust ventilation) and with and without the use of PPE (e.g.,
respirator).

6)	Map or group each condition of use to occupational exposure assessment scenario(s).

EPA has identified occupational exposure scenarios and mapped them to relevant conditions of
use (see Appendix F). As presented in the fourth column in Table Apx F-l, EPA has completed
an initial mapping of exposure scenarios to conditions of use. The Agency plans to refine
mapping or grouping of occupational exposure scenarios based on factors (e.g., process
equipment and handling, magnitude of production volume used, and exposure/release sources)
corresponding to conditions of use as additional information is identified. EPA may perform
supplemental targeted searches of peer-reviewed or gray literature to better understand certain
conditions of use to further develop exposure scenarios.

7)	Evaluate the weight of the scientific evidence of occupational exposure data, which may
include qualitative and quantitative sources of information.

During risk evaluation, EPA plans to evaluate and integrate the exposure evidence identified in
the literature inventory using revised systematic review methods described in the Agency's Draft
Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances
(December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414). EPA plans to rely on the weight
of the scientific evidence when evaluating and integrating occupational data. EPA also plans to
integrate the data using systematic review methods to assemble the relevant data, evaluate the
data for quality and relevance, including strengths and limitations, followed by synthesis and
integration of the evidence.

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2.7.2.4 Consumer Exposures

EPA plans to analyze both consumers using a consumer product and bystanders associated with the
consumer using the product as follows:

1)	Group each condition of use to consumer exposure assessment scenario(s).

EPA plans to refine and finalize exposure scenarios for consumers by considering combinations
of sources (ongoing consumer uses), exposure pathways including routes, and exposed
populations.

For D4, the following are noteworthy considerations in constructing consumer exposure
scenarios:

-	Conditions of use and type of consumer product;

-	Duration, frequency, and magnitude of exposure;

-	Weight fraction of chemical in products; and

-	Amount of chemical used.

2)	Evaluate the relative potential of indoor exposure pathways based on reasonably available
data.

Indoor exposures may include dust ingestion, mouthing of products, inhalation of indoor air and
dust, and dermal contact with dust, articles, and product use. EPA plans to evaluate all
reasonably available information in developing the consumer exposure scenarios and evaluating
the exposure pathways in indoor environments.

3)	Review existing indoor exposure models that may be applicable in estimating indoor air
concentrations.

Indoor exposure models that estimate emissions from consumer products are available. These
models generally consider physical and chemical properties (e.g., vapor pressure, molecular
weight), product specific properties (e.g., weight fraction of the chemical in the product), use
patterns (e.g., duration and frequency of use), user environment (e.g., room of use, ventilation
rates), and receptor characteristics (e.g., exposure factors, activity patterns). The OPPT's
Consumer Exposure Model (CEM) and other similar models can be used to estimate indoor air
exposures from consumer products.

Indoor exposure models that estimate emission and migration of semivolatile organic compounds
into the indoor environment are available. These models generally consider mass transfer as
informed by the gas-phase mass transfer coefficient, the solid-phase diffusion coefficient, and the
material-air partition coefficient. These properties vary based on physical and chemical
properties and properties of the material. The OPPT's Indoor Environmental Concentrations in
Buildings with Conditioned and Unconditioned Zones (IECCU) model and other similar models
can be used to estimate indoor air and dust exposures from indoor sources.

4)	Review reasonably available empirical data that may be used in developing, adapting, or
applying exposure models to a particular risk evaluation scenario. For example, existing
models developed for a chemical assessment may be applicable to another chemical
assessment if model parameter data are reasonably available.

To the extent other organizations have already modeled a D4 consumer exposure scenario that is
relevant to the OPPT's assessment (e.g., Gentry et at.. 2017. EC/HC. 2008). EPA plans to
evaluate those modeled estimates as well as modeled estimates for any other chemicals similar to

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D4 that have been modeled for similar uses. The underlying parameters and assumptions of the
models will also be evaluated.

5)	Review reasonably available consumer product-specific sources to determine how those
exposure estimates compare with each other and with indoor monitoring data reporting D4
in specific media (e.g., indoor air).

EPA plans to evaluate the availability of D4 concentration for various ongoing uses. These data
provide the source term for any subsequent indoor modeling. The Agency also plans to analyze
source attribution between overall indoor air levels and various indoor sources.

6)	Review reasonably available population- or subpopulation-specific exposure factors and
activity patterns to determine if PESS need to be further refined.

For D4, EPA plans to evaluate exposure scenarios that involve PESS and plans to consider age-
specific behaviors, activity patterns and exposure factors unique to those subpopulations. For
some exposure scenarios related to consumer uses, EPA also plans to consider whether
exposures for adults may differ from those of children due to different activities (e.g., children
may mouth certain products) or exposure factors (e.g., inhalation rates).

7)	Evaluate the weight of the scientific evidence of consumer exposure estimates based on
different approaches.

EPA plans to rely on the weight of the scientific evidence when evaluating and integrating data
related to consumer exposure. The weight of the scientific evidence may include qualitative and
quantitative sources of information. The Agency also plans to integrate the data using systematic
review methods to assemble the relevant data, evaluate the data for quality and relevance,
including strengths and limitations, followed by synthesis and integration of the evidence.

2.7.2.5 General Population

EPA plans to analyze general population exposures as follows:

1) Refine and finalize exposure scenarios for general population by considering combinations
of sources and uses, exposure pathways including routes, and exposed populations.

For D4, the following are noteworthy considerations in constructing exposure scenarios for the
general population:

-	Review reasonably available environmental and biological monitoring data for media to
which general population exposures are expected;

-	For exposure pathways where data are not reasonably available, review existing exposure
models that may be applicable in estimating exposure levels;

-	Consider and incorporate applicable media-specific regulations into exposure scenarios or
modeling;

-	Review reasonably available data that may be used in developing, adapting, or applying
exposure models to the particular risk evaluation. For example, existing models developed
for a chemical assessment may be applicable to another chemical assessment if model
parameter data are reasonably available;

-	Review reasonably available information on releases to determine how modeled estimates
of concentrations near industrial point sources compare with reasonably available
monitoring data;

-	Review reasonably available population- or subpopulation-specific exposure factors and
activity patterns to determine if PESS need to be further defined;

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-	Develop approaches and methodologies that use reasonably available information,
modeling, and geospatial analysis to evaluate impacts to population groups of concern
(e.g., fenceline and environmental justice communities);

-	Evaluate the weight of the scientific evidence of general population exposure data; and

-	Map or group each condition of use to general population exposure assessment scenario(s).

EPA plans to evaluate a variety of data types to determine which types are most appropriate
when quantifying exposure scenarios. Environmental monitoring data, biomonitoring data,
modeled estimates, experimental data, epidemiological data, and survey-based data can all be
used to quantify exposure scenarios. EPA anticipates that there will be a range in the potential
exposures associated with the exposure scenarios identified in Section 2.6.

After refining and finalizing exposure scenarios, EPA plans to quantify concentrations and/or
doses for these scenarios. The number of scenarios will depend on how combinations of uses,
exposure pathways, and receptors are characterized. The number of scenarios is also dependent
upon the reasonably available data and approaches to quantify scenarios. When quantifying
exposure scenarios, EPA plans to use a tiered approach. First-tier analysis is based on data that is
reasonably available without a significant number of additional inputs or assumptions, and may
be qualitative, semi-quantitative, or quantitative. The results of first-tier analyses inform whether
scenarios require more refined analysis. Refined analyses will be iterative and require careful
consideration of variability and uncertainty.

2)	For exposure pathways where empirical data are not reasonably available, review existing
exposure models that may be applicable in estimating exposure levels.

For D4, media where exposure models may be considered for general population exposure
include models that estimate concentrations in ambient air, drinking water, surface water,
groundwater, sediment, soil, and uptake from aquatic and terrestrial environments into edible
aquatic and terrestrial organisms.

3)	Review reasonably available exposure modeled estimates. For example, existing models
developed for a previous D4 chemical assessment may be applicable to EPA's assessment.
In addition, another chemical's assessment may also be applicable if model parameter data
are reasonably available.

To the extent other organizations have already modeled D4 general population exposure scenario
that is relevant to this assessment, EPA plans to evaluate those modeled estimates. In addition, if
modeled estimates for other chemicals with similar physical and chemical properties and similar
uses are reasonably available, the Agency plans to evaluate those modeled estimates, along with
their underlying parameters and assumptions.

4)	Review reasonably available information on releases to determine how modeled estimates
of concentrations near industrial point sources compare with reasonably available
monitoring data.

The expected releases from industrial facilities are changing over time. EPA plans to carefully
compare any modeled concentrations based on recent release estimates with reasonably available
monitoring data to determine representativeness.

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5)	Review reasonably available information about population- or subpopulation-specific
exposure factors and activity patterns to determine if PESS need to be further defined (e.g.,
early life and/or puberty as a potential critical window of exposure).

EPA plans to consider age-specific behaviors, activity patterns, and exposure factors unique to
any PESS for exposure scenarios that involve those subpopulations (e.g., children may have
different intake rates for soil than adults, infants may be exposed via ingestion of human milk).

6)	Evaluate the weight of the scientific evidence of general population exposure estimates
based on different approaches.

During risk evaluation, EPA plans to evaluate and integrate the exposure evidence submitted in
the request for risk evaluation as well as evidence identified in the literature inventory using
revised systematic review methods described in the Agency's Draft Systematic Review Protocol
Supporting TSCA Risk Evaluations for Chemical Substances (December 20, 2021) (Docket No.

EP A-HO-OPPT-2021 -04141

2.7.3 Hazards (Effects)

2.7.3.1 Environmental Hazards

EPA plans to conduct an environmental hazard assessment of D4 according to the steps below. The
Agency will consider all reasonably available information on D4 degradation products for inclusion in
the risk evaluation pending the data evaluation, synthesis, and integration phases of systematic review.

1)	Review reasonably available environmental hazard data, including data from alternative
test methods (e.g., computational toxicology and bioinformatics, high-throughput screening
methods, data on categories and read-across, in vitro studies).

EPA plans to analyze the hazards of D4 to aquatic and/or terrestrial organisms, including plants,
invertebrates (e.g., insects, arachnids, mollusks, crustaceans), and vertebrates (e.g., mammals,
birds, amphibians, fish, reptiles) across exposure durations and conditions if potential
environmental hazards are identified through the SEHSC submission, systematic review results,
or public comments. The Agency also plans to consider additional types of environmental hazard
information (e.g., analogue and read-across data) when characterizing the potential hazards of
D4 to aquatic and/or terrestrial organisms.

EPA plans to evaluate environmental hazard data using revised evaluation strategies described in
the Agency's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414). The study evaluation
results will be documented in the risk evaluation phase, and data from acceptable studies will be
extracted and integrated in the risk evaluation process.

Mechanistic data may include analyses of alternative test data such as novel in vitro test methods
and high throughput screening, which will be integrated in the risk evaluation process for hazard
and risk characterization (i.e., determination of mode of action [MO A] key events, susceptibility
factors, and human relevance). The association between acute and chronic exposure scenarios to
the agent and each health outcome will also be integrated. Study results will be extracted and
presented in evidence tables or another appropriate format by organ/system.

2)	Derive hazard thresholds for aquatic and/or terrestrial organisms.

Depending on the robustness of the evaluated data for a particular organism or taxa (e.g., aquatic
invertebrates), environmental hazard values (e.g., effect concentration [ECx], lethal concentration

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[LCx], no observable effect concentration [NOEC], lowest observable effect concentration
[LOEC]) may be derived and used to further understand the hazard characteristics of D4 to
aquatic and/or terrestrial species. Identified environmental hazard thresholds may be used to
derive concentrations of concern, toxic reference values, and/or other relevant hazard thresholds
based on endpoints that may affect populations of organisms or taxa analyzed.

3)	Evaluate the weight of the scientific evidence of environmental hazard data.

During risk evaluation, EPA plans to evaluate and integrate the environmental hazard evidence
identified in the literature inventory using revised systematic review methods described in the
Agency's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (December 20, 2021) (Docket No. EPA-HO-Q] 21-0414V

4)	Consider the route(s) of exposure, based on reasonably available monitoring and modeling
data and other reasonably available approaches to integrate exposure and hazard
assessments.

EPA plans to consider aquatic (e.g., water and sediment exposures) and terrestrial pathways in
the D4 conceptual model (Figure 2-15). These organisms may be exposed to D4 via a number of
environmental pathways (e.g., air, surface water, sediment, soil, diet).

5)	Consider a persistent, bioaccumulative, and toxic (PBT) assessment of D4.

EPA plans to consider the PBT potential of D4 after reviewing relevant physical and chemical
properties and exposure pathways. The Agency also plans to assess the studies submitted in the
request for risk evaluation as well as reasonably available studies collected from the systematic
review process relating to bioaccumulation and bioconcentration (e.g., bioaccumulation factor
[BAF], bioconcentration factor [BCF], biomagnification factor [BMF], trophic magnification
factor [TMF]) of D4. In addition, EPA plans to integrate traditional environmental hazard
endpoint values (e.g., LCso, LOEC) and exposure concentrations (e.g., surface water
concentrations, tissue concentrations) for D4 with the fate parameters (e.g., BAF, BCF, BMF,
TMF).

2.7.3.2 Human Health Hazards

EPA plans to analyze human health hazards according to the steps below. The Agency will also consider
all reasonably available information on D4 degradation products for inclusion in the risk evaluation
pending the data evaluation, synthesis, and integration phases of systematic review.

1) Review reasonably available human health hazard data, including data from human and
animal studies (human health animal models defined in Table Apx A-4) and alternative
test methods (e.g., computational toxicology and bioinformatics; high-throughput screening
methods; data on categories and read-across; in vitro studies; systems biology).

EPA plans to evaluate human health studies using revised evaluation strategies described in the
Agency's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical
Substances (December 20, 2021) (Docket No. EPA-HO-Q] 21-0414V These evaluation
strategies also apply to human health studies described in the SEHSC submission for D4 (EPA-
HQ-OPPT-2018-0443). EPA also plans to document the study evaluation results in the risk
evaluation phase, to extract data from acceptable studies, and to integrate those data into the risk
evaluation process.

Mechanistic data may include analyses of alternative test data such as novel in vitro test methods
and high throughput screening, which will be integrated in the risk evaluation process for hazard

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and risk characterization (i.e., determination of MOA key events, susceptibility factors, human
relevance). The association between acute and chronic exposure scenarios to the agent and each
health outcome will also be integrated. Study results will be extracted and presented in evidence
tables or another appropriate format by organ/system.

2)	In evaluating reasonably available data, identify any PESS that may have greater
susceptibility to the chemical's hazard(s) than the general population.

Reasonably available human health hazard data will be evaluated to ascertain whether some
human receptor groups may have greater susceptibility than the general population to D4
hazard(s). Susceptibility of particular human receptor groups to D4 will be determined by
evaluating information on factors that influence susceptibility.

EPA has reviewed some sources containing hazard information associated with PESS and
lifestages such as pregnant women and infants. Women of childbearing age (and those who may
become pregnant) were identified as a sensitive subpopulation. Pregnancy {i.e., gestation) and
childhood are potential susceptible lifestages for D4 exposure. The Agency may quantify these
differences in the risk evaluation following further evaluation of the reasonably available data
and information. If the reasonably available data and information are insufficient for the
identification of human health hazard endpoints for PESS, EPA will consider alternative
approaches including consideration of the identified susceptibility factors in the application of an
intraspecies uncertainty/variability factor in the risk characterization.

3)	Conduct hazard identification (the qualitative process of identifying non-cancer and cancer
endpoints) and dose-response assessment (the quantitative relationship between hazard
and exposure) for identified human health hazard endpoints.

Human health hazards from acute and chronic exposures will be identified by evaluating the
human and animal data that meet the revised systematic review data quality criteria, which will
be described in EPA's Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for
Chemical Substances (December 20, 2021) (Docket No. EPA-HQ-QPPT-2021 -0414). Hazards
identified by studies meeting acceptable data quality criteria will be grouped by routes of
exposure relevant to humans {e.g., oral, dermal, inhalation) and by cancer and non-cancer
endpoints identified in Section 2.4.2.

Dose-response assessment will be performed in accordance with EPA guidance (U.S. EPA.
2012a. 20 lib, I' >' > 0 developing PODs for either margins of exposure , cancer slope factors
(CSFs), oral slope factors (OSFs), and/or inhalation unit risks (IURs). Dose-response analyses
may be used if the data meet data quality criteria and if additional information on the identified
hazard endpoints are not reasonably available or would not alter the analysis.

The cancer MOA analyses determine the relevancy of animal data to human risk and how data
can be quantitatively evaluated. If the D4 cancer hazard is determined to be relevant to humans,
EPA plans to evaluate information on genotoxicity and the MOA for all cancer endpoints to
determine the appropriate approach for quantitative cancer assessment in accordance with the
U.S. EPA Guidelines for Carcinogen Risk Assessment (U.S. EPA. 2005a). In accordance with
EPA's Supplemental Guidance for Assessing Susceptibility from Early-life Exposures to
Carcinogens (	005b). the Agency plans to determine whether age-dependent

adjustment factors (ADAFs) are appropriate for D4 for specific conditions of use based upon
potential exposures to children.

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4)	Derive PODs where appropriate; conduct benchmark dose modeling depending on the
reasonably available data. Adjust the PODs as appropriate to conform (e.g., adjust for
duration of exposure) to the specific exposure scenarios evaluated.

EPA plans to evaluate hazard data to determine the type of dose-response modeling that is
applicable. Where modeling is feasible, a set of dose-response models that are consistent with a
variety of potentially underlying biological processes will be applied to empirically model the
dose-response relationships in the range of the observed data consistent with EP A's Benchmark
Dose Technical Guidance Document (U.	2012a). Where dose-response modeling is not

feasible, no observed adverse effect levels (NOAELs) or lowest observed adverse effect levels
(LOAELs) will be identified. Non-quantitative data will also be evaluated for contribution to the
weight of the scientific evidence or for evaluation of qualitative endpoints that are not
appropriate for dose-response assessment.

EPA plans to evaluate whether the reasonably available PBPK and empirical kinetic models are
adequate for route-to-route and interspecies extrapolation of the POD, or for extrapolation of the
POD to standard exposure durations (e.g., lifetime continuous exposure). If application of the
PBPK model is not possible, oral PODs may be adjusted by BW3 4 scaling in accordance with
I v < < \ >VJ01 I b)> ar|d inhalation PODs may be adjusted by exposure duration and chemical
properties in accordance with (U.S. EPA. 1994).

5)	Evaluate the weight of the scientific evidence of human health hazard data.

During risk evaluation, EPA plans to evaluate and integrate the human health hazard evidence
identified in the literature inventory under acute and chronic exposure conditions using revised
systematic review methods described in EPA's Draft Systematic Review Protocol Supporting
TSCA Risk Evaluations for Chemical Substances (December 20, 2021) (Docket No. EPA-HQ-

OPPT~2(	).

6)	Consider the route(s) of exposure (e.goral, inhalation, dermal), reasonably available
route-to-route extrapolation approaches, biomonitoring data, and approaches to correlate
internal and external exposures to integrate exposure and hazard assessment.

EPA plans to evaluate the reasonably available data to determine whether it is sufficient to
conduct dose-response analysis and/or benchmark dose modeling for the oral route of exposure.
EPA plans to also evaluate any potential human health hazards following dermal and inhalation
exposure to D4, which could be important for worker, consumer, and general population risk
analysis. Reasonably available data will be assessed to determine whether or not a point of
departure can be identified for the dermal and inhalation routes.

If sufficient reasonably available toxicity studies are not identified through the systematic review
process to assess risks from dermal or inhalation exposures, then a route-to-route extrapolation
from oral toxicity studies may be needed. The preferred approach is to use a PBPK model (U.S.
EPA. 2006a). Without an adequate PBPK model, considerations regarding the adequacy of data
for route-to-route extrapolation are described in Methods for Derivation of Inhalation Reference
Concentrations and Application of Inhalation Dosimetry (	|). EPA may use these

considerations when determining whether to extrapolate from the oral to the inhalation route of
exposure. Similar approaches for oral-to-dermal route extrapolation are described in EPA's
guidance document Risk Assessment Guidance for Superfund Volume I: Human Health
Evaluation Manual (PartE, Supplemental Guidance for Dermal Risk Assessment) (

2004).

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If there are acceptable oral and inhalation data after completion of systematic review, EPA may
also consider extrapolating from the inhalation to the dermal route if first-pass metabolism
through the liver via the oral route is expected because in that case, use of data from the oral
route is not recommended (	). The Agency may also consider inhalation-to-

dermal route extrapolation if an inhalation toxicity study with a sensitive hazard endpoint is used
to evaluate risks. Based on these considerations, EPA extrapolated from the inhalation to the
dermal route for the methylene chloride (	20d), carbon tetrachloride (

2020b). and perchloroethylene (\ v < < \ -020c) risk evaluations under amended TSCA.

2.7.4 Summary of Risk Approaches for Characterization

EPA plans to conduct a risk estimation and characterization of D4 to identify if there are risks to the
environment or human health. For environmental risk characterization, EPA plans to identify if there are
risks to aquatic and/or terrestrial environments from the measured and/or predicted concentrations of D4
in environmental media (e.g., air, water, sediment, soil). Risk quotients (RQs) may be derived by the
application of hazard and exposure benchmarks to characterize environmental risk (	8;

Barnthouse et at.. 1982). Similarly, for human health risk characterization, EPA plans to integrate
exposure estimates from measured and/or modeled data with hazard data to characterize risk to human
health. Analysis of environmental or human health risk for characterization includes a confidence
statement in risk estimation. This confidence statement is based on qualitative judgment describing the
certainty of the risk estimate considering the strength of the evidence scores for hazard and exposure
along with their limitations and relevance. The lowest confidence evaluation for either hazard or
exposure will drive the overall confidence estimate.

Risk characterization is an integral component of the risk assessment process for both environmental and
human health risks. EPA plans to derive the risk characterization in accordance with the Agency's Risk
Characterization Handbook (U.S. EPA. 2000). As defined in EPA's Risk Characterization Policy, "the
risk characterization integrates information from the preceding components of the risk evaluation and
synthesizes an overall conclusion about risk that is complete, informative and useful for decision
makers." Risk characterization is considered to be a conscious and deliberate process to bring all
important considerations about risk, not only the likelihood of the risk but also the strengths and
limitations of the assessment, and a description of how others have assessed the risk into an integrated
picture.

The level of information contained in each risk characterization varies according to the type of
assessment for which the characterization is written. Regardless of the level of complexity or
information, the risk characterization for TSCA risk evaluations will be prepared in a manner that is
transparent, clear, consistent, and reasonable (TCCR) (U.S. EPA. 2000) and consistent with the
requirements of the Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances
Control Act (82 FR 33726, July 20, 2017). As discussed in 40 CFR 702.43, risk characterization has a
number of considerations. This is the step where EPA integrates the hazard and exposure assessments
into risk estimates for the identified populations (including any PESS) and ecological characteristics and
weighs the scientific evidence for the identified hazards and exposures. The risk characterization does
not consider costs or other non-risk factors, and takes into account, "where relevant, the likely duration,
intensity, frequency, and number of exposures under the condition(s) of use...." The risk
characterization also summarizes the following considerations: (1) uncertainty and variability in each
step of the risk evaluation; (2) data quality, and any applicable assumptions used; (3) alternative
interpretations of data and analyses, where appropriate; and (4) any considerations for environmental
risk evaluations, if necessary (e.g., related to nature and magnitude of effects).

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EPA also plans to be guided by the Agency's Information Quality Guidelines (	002) as it

provides guidance for presenting risk information. Consistent with those guidelines, EPA plans to
identify in the risk characterization the following: (1) each population addressed by an estimate of
applicable risk effects; (2) the expected risk or central estimate of risk for the PESS affected; (3) each
appropriate upper- or lower-bound estimate of risk; (4) each significant uncertainty identified in the
process of the assessment of risk effects and the studies that would assist in resolving the uncertainty;
and (5) peer-reviewed studies known to EPA that support, are directly relevant to, or fail to support any
estimate of risk effects and the methodology used to reconcile inconsistencies in the scientific
information.

2.8 Peer Review

The draft risk evaluation for D4 will be peer reviewed. Peer review will be conducted in accordance
with EPA's regulatory procedures for chemical risk evaluations, including using EPA's Peer Review
Handbook (U.S. EPA. 2015b) and other methods consistent with section 26 of TSCA (see 40 CFR
702.45). As explained in the final rule Procedures for Chemical Risk Evaluation Under the Amended
Toxic Substances Control Act (82 FR 33726, 33744; July 20, 2017), the purpose of peer review is for the
independent review of the science underlying the risk assessment. Peer review will therefore address
aspects of the underlying science as outlined in the charge to the peer review panel such as hazard
assessment, assessment of dose-response, exposure assessment, and risk characterization.

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REFERENCES

3M. (2018). Safety Data Sheet: 3M Flow Additive 892 [Fact Sheet] (Version number 6.00 ed.). St. Paul,
MN.

https://multimedia.3m. com/mws/mediawebserver?mwsId=SSSSSuUn zu8100x4YtSPY 9mv70k
Ivu91xtD 7SSSSSS.

3M. (2019). Safety data sheet: Scotchgard leather and vinyl protector, 38601 [Fact Sheet] (Version
number 5.03 ed.). St. Paul, MN.

https://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSuUn zu8100xM8 vPYtBnv70k
Ivu91xtD 7SSSSSS.

Abe. Y; Butler. GB; Hogen-Esch. TE. (1981). Photolytic oxidative degradation of

octamethylcyclotetrasiloxane and related compounds. Journal of Macromolecular Science: Part
A - Chemistry 16: 461-471. http://dx.doi.ore 10/00222338108058483.

Alpine Specialty Chemicals Ltd. (2016a). Safety data sheet: Alpine green choice elite laundry detergent
with freshener. Etobicoke, Ontario.

https://www.alpinechem.com/pdfs/sds/Elite Laundry Detergent with Freshener SDS.pdf.
Alpine Specialty Chemicals Ltd. (2016b). Safety data sheet: Alpine green choice laundry detergent.

Etobicoke, Ontario. https://www.alpinechem.com/pdfs/sds/Laundry Detergent SDS.pdf.

Alton. 'M jwne. EC. (2020). Atmospheric chemistry of volatile methyl siloxanes: Kinetics and
products of oxidation by OH radicals and CL atoms. Environ Sci Technol 54: 5992-5999.
http://dx.doi.org/10.102 i/acs.est.0c01368.

Atkinson. R. (1991). Kinetics of the gas-phase reactions of a series of organosilicon compounds with
OH andN03 radicals and 0-3 at 297 +/- 2-K. Environ Sci Technol 25: 863-866.
http://dx.doi.org/10.102 l/es00017a005.

aiding LLC. (2019). Safety data sheet: Jade ceramic coating - ice (Version number 3.0 ed.).
Northglenn, CO.

Berruai! I "jpanastasiou. DK; Papadimitriou <'urkholdei Jl> (2018). Temperature dependent

rate coefficients for the gas-phase reaction of the OH radical with linear (L2, L3) and cyclic (D3,
D4) permethylsiloxanes. J Phys Chem A 122: 4252-4264.

http://dx.doi.org/10J02 i/acsjpca.8b01908.

Bletsou. AA; Asimakopoulos. AG; Stasinakis. AS; Thomaidis. NS: Kannan. K. (2013). Mass loading
and fate of linear and cyclic siloxanes in a wastewater treatment plant in Greece. Environ Sci
Technol 47: 1824-1832. hl!;: iK.doi.org 10 tO:t cs304369b.

Borga. K; FfI
-------
Submission], (HES study no. 11060-108. 88-100000163. 8EHQ-10-17834A). Dow Corning
Corporation, Health & Environmental Sciences.

Durham. J. (2005). Hydrolysis of octamethylcyclotetrasiloxane (D4). (HES study no. 2005-10000-

55551). Auburn, MI: Dow Corning Corporation, Health and Environmental Sciences.

EC/HC. (2008). Screening assessment for the challenge: Octamethylcyclotetrasiloxane (D4): CASRN
556-67-2. Gatineau, QC: Environment Canada. https://www.ec.gc.ca/ese-ees/2481B508-1760-
4878-9BS \ : 0EEE8B7DA4/bat l>. t . ^.pdf.

ECHA. (2012). Identification of PBT and vPvB substance: Results of evaluation of PBT / vPvB
properties: Octamethylcyclotetrasiloxane. Helsinki, Finland.
https://echa.europa.eu/documentS/101 . I'[40ef0~a0d2~4e93~884Q~a^ h' Is .V^ca.

ECHA. (2015a). Annex XV restriction report: Proposal for a restriction. Octamethylcyclotetrasiloxane
and decamethylcyclopentasiloxane. Version 1.1. Helsinki, Finland.
https://echa.europa.eu/documentS/ i"i . f9a53a4d9^i II lb h-ad58-8fec6cf26229.

ECHA. (2015b). Member State committee (MSC) opinion on persistency and bioaccumulation of

octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5). Helsinki, Finland.
https://echa.europa.eu/about~us/who~we~are/member~state~committee/opinions~of~the~msc~
adopted-under-specific-echa-s-executive-director-requests.

Ecolab. (2017). Safety data sheet: FaciliPro Fabric Softener. St. Paul, MN.

Ecolab. (2019). Safety data sheet: Low Temp Laundry Clearly Soft. St. Paul, MN.

https://safetvdata.ecolab.com/svc/GctPdf i o\s h MP LAUNDRY CIJ \K! \ c-OFT Englis
h?sid=900648-08&cntrv=US&langid=en-

US&lann\ t"' Mi I 1 angCode&locale=en&pdfname=LOW TEMV I M M v I J
Y SOFT English.pdf.

.Fadder, PI 1. .Dtonne. Fs, .Hartlc	.meltn 1c. (1995). Bioconcentration by fish of a highly

volatile silicone compound in a totally enclosed aquatic exposure system. Environ Toxicol Chem
14: 1649. http://dx.doi.org,	tc.5620141004.

Fendinger. NJ; McA.vo'\ 1 * >1 khofi \\ v l\t ^ (1997). Environmental occurrence of

polydimethylsiloxane. Environ Sci Technol 31: 1555-1563. http://dx.doi.org/10 10. I ^s960N I J
I ii'iame. H; Cequier. E; Kim. IT; Hanssen. L; Hilge> Ihomseri i t hang \v \ > Ucel. W. (2015).
Persistent and emerging pollutants in the blood of German adults: Occurrence of dechloranes,
polychlorinated naphthalenes, and siloxanes. Environ Int 85: 292-298.
http://dx.doi.org/10 J 016/i .envint.-O I 0 00
Gatidou. G; Arvaniti. OS: Stasinakis. AS; Thomaidis. NS: Andersen. HR. (2016). Using mechanisms of
hydrolysis and sorption to reduce siloxanes occurrence in biogas of anaerobic sludge digesters.
Bioresour Technol 221: 205-213. http://dx.doi.oi ^ 10 101 '/i.biortech.,01 00l\

Gentry. R; Franzen. A: Van Landingham. C; Greene jtzke. K. (2017). A global human health risk
assessment for octamethylcyclotetrasiloxane (D4). Toxicol Lett 279: 23-41.
http://dx.doi.org/10 J 016/i.toxlet.L01 0 0 r"

Gledhill. WE. (2005). Determining the biodegradability of octamethylcyclotetrasiloxane based on the
draft OECD 310 sealed vessel C02 evolution biodegradation test. (Springborn Smithers Study
No. 12023.6146). Wareham, MA: Springborn Smithers Laboratories.

Grumping. R; Michalke. K; Hirner. AV: Hensel. R (1999). Microbial degradation of
octamethylcyclotetrasiloxane. Appl Environ Microbiol 65: 2276-2278.
http://dx.doi.ore 10 I 128/AEM.65.5.1. __m
Hanssen. L; Warner. NA: Braathen. T: Odland. 10; Lun > I Nieboer. E; San danger. TM. (2013).
Plasma concentrations of cyclic volatile methylsiloxanes (cVMS) in pregnant and
postmenopausal Norwegian women and self-reported use of personal care products (PCPs).
Environ Int 51: 82-87. http://dx.doi.oi ^ 10 101 /i. en vim JO IJ 10 00S.

Page 63 of 124


-------
Hone. WJ; Jia. H; Liu. C; Zhang. Z; Sun. YF. (2014). Distribution, source, fate and

bioaccumulation of methyl siloxanes in marine environment. Environ Pollut 191: 175-181.
http://dx.doi.org/10 J 016/i .envpol.2014.04.033.

Horii. Y; Noiiri. K; Minomo. K; Motegi. M; Kannan. K. (2019). Volatile methylsiloxanes in sewage

treatment plants in Saitama, Japan: Mass distribution and emissions. Chemosphere 233: 677-686.
http://dx.doi.org/10 J 016/i .chemosphere.. ^ l ^ .1

H.ow>m! Tn1 Phillip1 t \ tiller. K; Tandon. A; M. I* v hah. MR; Holmgren. S: Pelch. KE; Walker. V:
Root	eod. M; Shah. RR; Thayer. K. (2016). SWIFT-Review: a text-mining

workbench for systematic review. Syst Rev 5: 87. http://dx.doi.on 10 I 186/? I'< l'< 01 0,.63-z.

HvdroQual Inc. (1993). Sampling and analysis for D4 (octamethy 1 cyclotetrasi 1 oxane) at selected

wastewater treatment plants with cover letter dated 06/11/93 [TSCA Submission], (SHC00020.
OTS0557025. 86940000615. TSCATS/442495). Silicones Health Co.

Jia. H; Zhang. Z; Wang. C; Hong. WJ; Si	(2015). Trophic transfer of methyl siloxanes in

the marine food web from coastal area of Northern China. Environ Sci Technol 49: 2833-2840.
http://dx.doi.org/10.102 i/es505445e.

K ^ it UcNama*  I I V Hob son .11', Silberhorn. EM. (1994). Octamethylcvclotetrasiloxane
in aquatic sediments: Toxicity and risk assessment. Ecotoxicol Environ Saf 29: 372-389.
http://dx.doi.on 10 101 Oil ^ I Vs 1)90010-8.

Kim. J; Xu. S. (2017). Quantitative structure-reactivity relationships of hydroxyl radical rate constants
for linear and cyclic volatile methylsiloxanes. Environ Toxicol Chem 36: 3240-3245.
http://dx.doi.oo 02/etc.3914.

Kirk-Othmer. (2008). Kirk-Othmer Encyclopedia of Chemical Technology
Silicones. Hoboken, NJ: Wiley.

http://dx.doi.on 10 1002/0 I i. 8961.1909120918090308.aO 1 .pub2.

Kozerski. GE; Xu. S; Miller. J; Durham. J. (2014). Determination of soil-water sorption coefficients of
volatile methylsiloxanes. Environ Toxicol Chem 33: 1937-1945.
http://dx.doi.Org/http://dx.doi.org/10.1002/etc,2640.

Krogseth. IS; Undeman \ \ rens^t \ Christensen. GN; Whelan. MJ; Breivik. K; Warner. NA. (2017).
Elucidating the behavior of cyclic volatile methylsiloxanes in a subarctic freshwater food web: A
modeled and measured approach. Environ Sci Technol 51: 12489-12497.
http://dx.doi.oo	ics.est.7b03083.

Lehmann. RG; Milter. JR.; Collins. HP. (1998). Microbial Degradation of Dimethylsilanediol in Soil.
Water Air Soil Pollut 106: 111-122.
http://dx.doi. or g/http ://dx. doi.

Lehmann. RG; Miller. JR; Kozerski. GE. (2000). Degradation of silicone polymer in a field soil under
natural conditions. Chemosphere 41: 743-749. http://dx.doi.org/10.1016/s0045~6535f99)00430~

0.

U T ( 1. WL; Sun.	^ Ma. WL; ] tit * \ hang. ZF; Zhu. NZ; Li b (2016). The occurrence

and fate of siloxanes in wastewater treatment plant in Harbin, China. Environ Sci Pollut Res Int
23: 13200-13209. http://dx.doi.or

McGoldrick t han. C; Drouill 0  ^ ^ nr. KI t iark. MG; Backus. SM. (2014). Concentrations and
trophic magnification of cyclic siloxanes in aquatic biota from the Western Basin of Lake Erie,
Canada. Environ Pollut 186: 141-148. http://dx.doi.org, 10 101 | envpol. JO I '< i J 003.

Mueller. J A; Di Toro. DM; Mai ell o. J A. (1995). Fate of octamethylcyclotetrasiloxane (OMCTS) in the
atmosphere and in sewage treatment plants as an estimation of aquatic exposure. Environ
Toxicol Chem 14: 1657-1666. http://dx.doi.org/10.1897/1552-
8618(1995) 14[ 165 7 :FOOOIT )^2.

NLM. (2020). PubChem database: compound summary: Octamethylcyclotetrasiloxane [Website],
https://piibchem.ncbi.nlm.nih.gov/compoimc K

Page 64 of 124


-------
Norwegian Environment Agency. (2019). Environmental contaminants in an urban fjord, 2018. (M-
1441). Trondheim, Norway, https://www.miliodirektoratet.no/publikasi oner/2019/september-

2019/envir-onmental-contaminants-in-an-urban-fiord-2018/.

OECD. (2004). Emission scenario document on additives in rubber industry.
(ENV/JM/MONO(2004)11). Paris, France.

http://www.oecd.org/officialdocuments/publicdisplavdocumentpdf/?cote=env/im/mono(2Qi

& docl an guage=en.

OECD. (2009a). Emission scenario document on adhesive formulation. (ENV/JM/MONO(2009)3;
JT03263583). Paris, France.

http://www.oecd.org/officialdocuments/publicdisplavdocumentpdf/?cote=env/im/mono(2QQ9)3&

doclanguage=en.

OECD. (2009b). Emission scenario documents on coating industry (paints, lacquers and varnishes).
(JT03267833). Paris, France.

http://www.oecd.org/officialdocuments/publicdisplavdocumentpdf/?cote=env%20/im/mono(200

9)24& docl an guage=en.

OECD. (2011). Emission scenario document on radiation curable coating, inks and adhesives.

(JT03304942). Paris: OECD Environmental Health and Safety Publications, http://www.oecd-
ilibrarv.org/docserver/downloadA	)df?expires=1497031939&id=id&accname=guest&c

hecksum=C794B2987D98	0.

OECD. (2015). Emission scenario document on use of adhesives. In Series on Emission Scenario
Documents No 34. (Number 34). Paris, France.

http://www.oecd.org/officialdocuments/publicdisplavdocumentpdf/?cote=ENV/JM/MONO(2Ql 5

)4& docl an guage=en.

Panagopoulos. D; Jahnke. A: Kierkegaari tacleod. M. (2015). Organic carbon/water and dissolved
organic carbon/water partitioning of cyclic volatile methylsiloxanes: Measurements and
polyparameter linear free energy relationships. Environ Sci Technol 49: 12161-12168.

http://dx.doi.org/10.1021/acs.est.5b02483.

Panagopoulos. D; Jahnke. A: Kierkegaari tacleod. M. (2017). Temperature Dependence of the

Organic Carbon/Water Partition Ratios (K-oc) of Volatile Methylsiloxanes. Environ Sci Technol
Lett 4: 240-245. http://dx.doi.org/10.1021 /acs.estlett.7b001 'A
Parker. WJ; Shi dinger. NJ: Monteith. HP; Chandra. G (1999). Pilot plant study to assess the fate
of two volatile methyl siloxane compounds during municipal wastewater treatment. Environ
Toxicol Chem 18: 172-181. http://dx.doi.org/10.1002/etc.5620180211.

Powell. DE; Schgyen. M; Oxnevad. S: Gerh
-------
Rust-Oleum Corporation. (2018). Safety data sheet: Pro 1-GL 2pk gloss leather brown 100VOC. Vernon
Hills, IL. https://www.mstoleum.com/MSDS/ENGLISH/242250.PDF.

Sabourin. CL; Carpenter. J ). TK; Spivack. JL. (1996). Biodegradation of di methyl si 1 anedi ol in
soils. Appl Environ Microbiol 62: 4352-4360. http://dx.doi.org 10 I I 28/AEM _ l_ I
4360.1996.

Sabourin. CL; Carpentei K  ^ib. TK; Spivack ,11 (1999). Mineralization of dimethylsilanediol by
microorganisms isolated from soil. Environ Toxicol Chem 18: 1913-1919.

Safro(i \ c.trandell. M; Kierkegaard \. N lacleod. M. (2015). Rate Constants and Activation Energies
for Gas-Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical.
Int J Chem Kinet 47: 420-428. http://dx.doi.org/10.1002/kin.2P'" r"

SEHSC. (2020). Request for risk evaluation under the Toxic Substances Control Act;

Octamethylcyclotetrasiloxane (D4; CASRN: 556-67-2). Washington, DC: American Chemistry
Council, https://www.epa.gov/sites/production/files/2Q20-
04/documents/d4 nirre dossier 28ian20J0 _ I |;df.

Shi. Y; Xu. S; Xu. L; Cai. Y. (2015). Distribution, Elimination, and Rearrangement of Cyclic Volatile
Methylsiloxanes in Oil-Contaminated Soil of the Shengli Oilfield, China. Environ Sci Technol
49: 11527-11535. http://dx.doi.org/10.1021/acs.est.5b03197.

Sigma Aldrich. (2018). Safety data sheet: D4 cyclomethicone (Version 5.6 ed.).

Sigma Aldrich. (2020). Safety data sheet: Octamethylcyclotetrasiloxane (Version 6.1 ed.).

Sommerlade. R; Parlar. H; Wrobel. D; Kochs. P. (1993). Product analysis and kinetics of the gas-phase
reactions of selected organosilicon compounds with OH radicals using a smog chamber-mass
spectrometer system. Environ Sci Technol 27: 2435. http://dx.doi.org/10.102 l/es0Q048
-------
(2005b). Supplemental guidance for assessing susceptibility from early-life exposure to
carcinogens [EPA Report], (EPA/630/R-03/003F). Washington, DC: U.S. Environmental
Protection Agency, Risk Assessment Forum.

https://www3.epa.eov/airtoxics/childrens supplement final.pelf.

(2006a). Approaches for the application of physiologically based pharmacokinetic (PBPK)
models and supporting data in risk assessment (Final Report) [EPA Report] (pp. 1-123).
(EPA/600/R-05/043F). Washington, DC: U.S. Environmental Protection Agency, Office of
Research and Development, National Center for Environmental Assessment.
http://cfpiib.epa.eov/ncea/cfm/recordisplay.cfm7dei

(2006b). A framework for assessing health risk of environmental exposures to children (pp.
1-145). (EPA/600/R-05/093F). Washington, DC: U.S. Environmental Protection Agency, Office
of Research and Development, National Center for Environmental Assessment.
http://cfpiib.epa.eov/ncea/cfm/recordisplay.cfm7dei 563.

(2011a). 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.
http://cfpub.epa. eov/ncea/cfm/recordisplay.cfm?deid=236252.

(201 lb). Recommended use of body weight 3/4 as the default method in derivation of the
oral reference dose (pp. 1-50). (EPA/100/R-11/0001). Washington, DC: U.S. Environmental
Protection Agency, Risk Assessment Forum, Office of the Science Advisor.
https://www.epa.eov/sites/prodiiction/files/2013-09/dociiments/recommended-use-ofibw34.pdf.

(2012a). Benchmark dose technical guidance. (EPA/100/R-12/001). Washington, DC: U.S.
Environmental Protection Agency, Risk Assessment Forum.
https://www.epa.eov/risk/benchmark-dose4echnical-euidance.

(2015a). ChemSTEER user guide - Chemical screening tool for exposures and environmental
releases. Washington, D.C. https://www.epa.gov/sites/production/files/2015-
05/documents/user euide.pdf.

(2015b). Peer review handbook [EPA Report] (4th ed.). (EPA/100/B-15/001). Washington,
DC: U.S. Environmental Protection Agency, Science Policy Council.
https://www.epa. eov/osa/peer-revi ew-h an db ook-4th -editi on -2015.

(2016). Technical guidance for assessing environmental justice in regulatory analysis.
Washington, DC: U.S. Environmental Protection Agency.

https://www.epa.eov/environmentaliiistice/technical-eiiidance-assessine-environmental-iiistice-
regulatory-analysis

(2019). CPCat: Chemical and Product Categories.
https://actor.epa.eov/cpcat/faces/home.xhtml.

(2020a). Chemical Data Reporting (2012 and 2016 Public CDR database). Washington, DC:
U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics.
https://chemview.epa.eov/chemview.

(2020b). Draft risk evaluation for carbon tetrachloride (methane, tetrachloro-); CASRN: 56-
23-5 (pp. 1-301). (EPA-740-R1-8014). Office of Chemical Safety and Pollution Prevention, U.S.
Environmental Protection Agency.

https://nepis.epa. eov/Exe/ZyPDF.cei/P100YHLJW.PDF?Dockey=P 100YHLJW.PDF.

(2020c). Draft risk evaluation for perchloroethylene. Washington, D.C.: U.S. Environmental
Protection Agency. Office of Chemical Safety and Pollution Prevention.

(2020d). Risk evaluation for methylene chloride (dichloromethane, dem); CASRN: 75-09-2
(pp. 1-753). (EPA-740-R1-8010). Office of Chemical Safety and Pollution Prevention, U.S.
Environmental Protection Agency, https://www.epa.gov/sites/production/files/2Q2Q-
06/documents/1 meel risk evaluation final.pdf.

Page 67 of 124


-------
Wane. DG: Aggarwal. M; Tail I Gamble. S; Pacepaviciir kinsman. L; Theocharides. M; Smyth.

ee. M. (2015). Fate of anthropogenic cyclic volatile methylsiloxanes in a wastewater
treatment plant. Water Res 72: 209-217. http://dx.doi.on 10 101 /j .watres.201 I 10 00 .

Wane. DG; Norwoc! \\ \ Liee. KI <1 \ ^r. JD; Brimble. S. (2013a). Review of recent advances in

research on the toxicity, detection, occurrence and fate of cyclic volatile methyl siloxanes in the
environment. Chemosphere 93: 711-725. http://dx.doi.c	5/i.chemosphere.2012.10.041.

Wane. DG: Steer. H; Tait. T; Williams. Z; Pacepaviciui- \ i 's ^ i v myth. SA: Kinsman. L:
Alaee. M. (2013b). Concentrations of cyclic volatile methylsiloxanes in biosolid amended soil,
influent, effluent, receiving water, and sediment of wastewater treatment plants in Canada.
Chemosphere 93: 766-773. http://dx.doi.ore/10.1016/j.chemosphere.201J 10 0 I .

Warren London. (2019). Warren London: K9 Silk & Shine [Website],
https://www.warrenlondon.com/products/k9-silk-shine.

Wildlife International Ltd. (2008). Octamethylcyclotetrasiloxane (D4): A bioaccumulation test with

Lumbriculus variegatus using spiked sediment [TSCA Submission], (570A-111. OTS0600246.
88-100000254. 8EHQ-0410-17925A). Centre Europeen des Silicones. European Chemical
Industry Council (CEFIC).

https://ntrl.ntis. gov/NT ;hboard/searchResults/titleDetail/OTS06QQ246.xhtml.

Woodburn. K: Drotuii i 1 ^moradzki. J: Durham. J: Mclvn 1 * ^ owski, R. (2013). Determination of
the dietary biomagnification of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane
with the rainbow trout (Oncorhynchus mykiss). Chemosphere 93: 779-788.
http://dx.doi.ore/http://dx.doi.ore/10.1016/j .chemosphere.20 i J iO 0

Xiao, k \tmmii i \\ ei. Z: Hu. WP: Macleod. M: Spinney. R. (2015). Kinetics and Mechanism of the
Oxidation of Cyclic Methylsiloxanes by Hydroxyl Radical in the Gas Phase: An Experimental
and Theoretical Study. Environ Sci Technol 49: 13322-13330.
http: //dx. doi. or g/10.1021 /ac s. est. 5b03 744.

Xu. L: He. X: Zhi. L: Zhang. C: Zene i. Y. (2016). Chlorinated methylsiloxanes generated in the
papermaking process and their fate in wastewater treatment processes. Environ Sci Technol 50:
12732-12741. http://dx.doi.org/10.1021/acs.est.6bC

Xu. L: Shi. Y: Cai. Y. (2013). Occurrence and fate of volatile siloxanes in a municipal wastewater
treatment plant of Beijing, China. Water Res 47: 715-724.
http://dx.doi.ore/10.1016/j .watres.2012.10.046.

Xu. L: Shi. Y: Wan ong. Z: Su. W: Cai. Y. (2012). Methyl siloxanes in environmental matrices

around a siloxane production facility, and their distribution and elimination in plasma of exposed
population. Environ Sci Technol 46: 11718-11726. http://dx.doi.org/10.1021/es3023368.

Xu. L: Xu. S: Zhang. O: Zhang. S: Tian. Y: Zhao. Z: C; (2019a). Chlorinated-methyl siloxanes in
Shengli oilfield: Their generation in oil-production wastewater treatment plant and presence in
the surrounding soils. Environ Sci Technol 53: 3558-3567.
http://dx.doi.org/10J02 i/acs.est.8b06993.

Xu. S. (1999). Fate of cyclic methylsiloxanes in soils. 1. The degradation pathway. Environ Sci Technol
33: 603-608. http://dx.doi.org/10.102 i /es980803a.

Xu. S. (2007). Estimation of degradation rates of cVMS in soils. (HES study no. 10787-102). Auburn,
MI: Dow Corning Corporation, Health and Environmental Sciences.

Xu. S. (2009). Anaerobic transformation of octamethy 1 cyclotetrasi 1 oxane (14C-D4) in aquatic sediment
systems. (Report no. 2009-10000-61734; HES study no. 11101-108). Midland, MI: Dow Corning
Corporation.

(2019). Extraction and quantitative analysis of water by GC/MS for trace-level dimethylsilanediol
(DMSD). J Chromatogr A 1600: 1-8. http://dx.doi.org/) 0 101 5/i .chroma.-0I'* 0 i O46.

Page 68 of 124


-------
Xu. S; Kropscol (2012). Method for simultaneous determination of partition coefficients for cyclic
volatile methylsiloxanes and dimethylsilanediol. Anal Chem 84: 1948-1955.

http://dx.doi.ore/10.1021/ac202953t.

Xu. S: Kropscol (2014). Evaluation of the three-phase equilibrium method for measuring

temperature dependence of internally consistent partition coefficients (KOW , KOA , and KAW
) for volatile methylsiloxanes and trimethylsilanol. Environ Toxicol Chem 33: 2702-2710.
http://dx.doi.on Q2/etc.2754.

Xu. S: Miller. J. (2008). Aerobic transformation of octamethy 1 cyclotetrasi 1 oxane (D4) in water/sediment
system. Interim report. (HES study no. 10714-108). Midland, MI: Dow Corning Corporation.

Xu. S: Miller. J. (2009). Aerobic transformation of octamethy 1 cyclotetrasi 1 oxane (14CD4) in aquatic

sediment systems. (HES Study No. 10885-108). Auburn, MI: Dow Corning Corporation, Health
and Environmental Sciences.

Xu. S: Warner. N: Bohlin-Nizzetto. P; Durham. J: McN (2019b). Long-range transport potential
and atmospheric persistence of cyclic volatile methylsiloxanes based on global measurements.
Chemosphere 228: 460-468. http://dx.doi.org/10.1016/i.chemosphere..O V 0 I l'<0

Xu. S11 t liandi . (1999). Fate of cyclic methylsiloxanes in soils. 2. Rates of degradation and
volatilization. Environ Sci Technol 33: 4034-4039. http://dx.doi.ore/10.1021/es990099d.

Xue. X; Jia. H; Xue. J. (2019). Bioaccumulation of methyl siloxanes in common carp (cyprinus carpio)
and in an estuarine food web in northeastern China. Arch Environ Contam Toxicol 76: 496-507.
http: //dx. doi. or e/http ://dx. dob	7/s00244-018-0569-z.

Xue. X; Jia. H; Xue. J. (2020). Reply to comment on "Bioaccumulation of methyl siloxanes in common
carp (Cyprinus carpio) and in an estuarine food web in Northeastern China" [Comment], Arch
Environ Contam Toxicol 78: 174-181. ht^; 
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APPENDICES

Appendix A ABBREVIATED METHODS FOR SEARCHING AND
SCREENING

A.l Literature Search of Publicly Available Databases

A.l.l	Search Term Genesis and Chemical Verification

To develop the chemical terms for the subsequent literature search for D4, several online sources were
queried:

	Chem Spider (Royal Society of Chemistry)

	ChemlDplus (NLM)

	FDA. Substance Registration System

	ECHA (European Chemicals Agency)

	US EPA. CompTox Chemicals Dashboard

	Common Chemistry (CAS resource)

	sticides Database

Prior to inclusion in the search term string, all forms of chemical names were subjected to verification
from several potential sources (e.g., US EPA Chemistry Dashboard, STN International-CAS; see
complete list of sources for chemical verification in Table Apx A-l). From these sources, all chemical
names, synonyms, CAS number(s), trade names, etc. were documented and used to generate terms for
database searches.

Table Apx A-l. Sources of Verification for Chemical Names and Structures

Chemical Source

Contents

Document Location

Chemistrv Dashboard

CAS Numbers, Synonyms, Structures,
Properties, Environmental Fate and
Transport.

Online

Dictionary of Chemical Names and
Synonyms

Wide assortment of chemical
compounds by chemical name and
synonym, has CAS index and some
structure data

ECOTOX

Farm Chemicals Handbook-1992

Pesticide information, CAS numbers and
synonyms, some structure data"

ECOTOX

OPPT SMILES Verification Source

Structure data

Electronic verification

RTECS (Registry of Toxic Effects of
chemical substance, 1983-84 ed., 2 vols)

Chemical names, synonyms, and CAS
numbers

ECOTOX

Sigma - Aldrich website

Organic and inorganic Compounds by
chemical name, has CAS index and
some structure and Physical Property
data

Online

STN International (CAS) 1994

Most complete source of chemical name,
synonym and structure information, no
physical properties

Online

Page 70 of 124


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Chemical Source

Contents

Document Location

The Pesticide Manual 10th edition, 1994

Pesticide compounds by chemical name,
synonym, product code, has CAS index
and some structure and physical property
data

ECOTOX

TSCA Chemical Substance Inventory,
1985 ed., 5 vols)

Chemical names, synonyms, and CAS
numbers

ECOTOX

World Wide Web (misc. web sources) A
copy of the verification page is saved to
the Attachments tab of the chemical
entry. This includes company MSDS
sheets or Chemical Labels.

Chemical names, synonyms, and CAS
numbers

Online

California Department of Pesticide
Regulation

Multiple databases containing chemicals,
pesticides, companies, products, etc.

Online

ticide Database

Pesticides searchable by name or CAS #.
Includes CAS #, name, synonyms,
targets, toxicity data, related chemicals,
and regulatory information.

Online

US EPA Office of Pesticide Programs
Pesticide Fate Database - No web access
available. An electronic copy of the data
file is located at the Contractor site:
PFATE_37_Tables.mdb.

Multiple databases containing chemicals,
pesticides, companies, products, etc.

Online

" Sometimes CAS number presented for a compound is for the main constituent only

A.1.2 Publicly Available Database Searches

The databases listed below were searched for literature containing the chemical search terms. An
information specialist conducted database searching during September 2020 for D4 and during January
2021 for the four degredation products described in Section 2.3.2. The results were stored in the Health
and Environmental Research Online (HERO) database and assigned a HERO reference identification
number.7 The present literature search focused only on the chemical name (including synonyms and
trade names) with no additional limits. Full details of the search strategy for each database are presented
in Appendix A. 1.2.1.

After initial deduplication in HERO,8 these studies were imported into SWIFT Review software
(Hoy al.. 2016) to identify those references most likely to be applicable to each discipline area
{i.e., consumer, environmental, and general population exposure, occupational exposure and
environmental releases, environmental hazards, human health hazards, and fate and physical chemistry).

7	EPA's HERO database provides access to the scientific literature behind EPA science assessments. The database includes
more than 600,000 scientific references and data from the peer-reviewed literature used by EPA to develop its regulations.

8	Deduplication in HERO involves first determining whether a matching unique ID exists (e.g., PMID, WOSid, DOI). If one
matches one that already exists in HERO, HERO will tag the existing reference instead of adding the reference again.
Second, HERO checks if the same journal, volume, issue, and page number are already in HERO. Third, HERO matches on
the title, year, and first author. Title comparisons ignore punctuation and case.

Page 71 of 124


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A_.1_.2J_ Query Strings for the Publicly Available Database Searches on D4

These are the search terms compiled for Octamethylcyclotetrasiloxane (D4) used in the initial search
strategies for each of the databases listed below:

"Octamethylcyclotetrasiloxane"OR ("D4" AND "siloxane") OR "556-67-2" OR "OMCTS" OR
"cyclotetrasiloxane" OR "Silbione" OR "Octamethylcyclotetrasiloxan" OR "VS 7207" OR
"Cyclotetrasiloxane, octamethyl-" OR "Cyclic dimethylsiloxane tetramer" OR "Dow Corning 344" OR
"Volasil 244" OR "DC 244" OR "DC 344" OR "Octamethylcyclotetrasiloxanes"

Table Apx A-2. Summary of Data Sources, Search Dates, and Number of Peer-Reviewed
Literature Search Results for Octamethylcyclotetrasiloxane (D4)	

Source

Source-Specific Search Strategy

Results

Agricola

Search Date:
9/4/2020

ALL("Octamethylcyclotetrasiloxane" OR ("D4" AND "siloxane") OR "556-67-
2" OR "OMCTS" OR "cyclotetrasiloxane" OR "Silbione" OR
"Octamethylcyclotetrasiloxan" OR "VS 7207" OR "Cyclotetrasiloxane,
octamethyl-" OR "Cyclic dimethylsiloxane tetramer" OR "Dow Corning 344"
OR "Volasil 244" OR "DC 244" OR "DC 344" OR
"Octamethylcyclotetrasiloxanes")

167

Current
Contents

Search Date:
9/4/2020

(TS="Octamethylcyclotetrasiloxane" OR (TS="D4" AND TS="siloxane") OR
TS="556-67-2" ORTS="OMCTS" OR TS="cyclotetrasiloxane" OR
TS="Silbione" OR TS="Octamethylcyclotetrasiloxan" OR TS="VS 7207" OR
TS="Cyclotetrasiloxane, octamethyl-" OR TS="Cyclic dimethylsiloxane
tetramer" OR TS="Dow Corning 344" OR TS="Volasil 244" OR TS="DC 244"
OR TS="DC 344" OR TS="Octamethylcyclotetrasiloxanes")

801

ProQuest
Dissertations
& Theses

Search Date:
9/4/2020

ALL("Octamethylcyclotetrasiloxane" OR ("D4" AND "siloxane") OR "556-67-
2" OR "OMCTS" OR "cyclotetrasiloxane" OR "Silbione" OR
"Octamethylcyclotetrasiloxan" OR "VS 7207" OR "Cyclotetrasiloxane,
octamethyl-" OR "Cyclic dimethylsiloxane tetramer" OR "Dow Corning 344"
OR "Volasil 244" OR "DC 244" OR "DC 344" OR
"Octamethylcyclotetrasiloxanes")

4

ProQuest
Agricultural
& Scientific
Database

Search Date:
9/4/2020

ALL("Octamethylcyclotetrasiloxane" OR ("D4" AND "siloxane") OR "556-67-
2" OR "OMCTS" OR "cyclotetrasiloxane" OR "Silbione" OR
"Octamethylcyclotetrasiloxan" OR "VS 7207" OR "Cyclotetrasiloxane,
octamethyl-" OR "Cyclic dimethylsiloxane tetramer" OR "Dow Corning 344"
OR "Volasil 244" OR "DC 244" OR "DC 344" OR
"Octamethylcyclotetrasiloxanes")

306

PubMed

Search Date:
9/4/2020

("Octamethylcyclotetrasiloxane"[tw] OR ("D4"[tw] AND "siloxanes"[MeSH])
OR "556-67-2"[rn] OR "OMCTS"[tw] OR "cyclotetrasiloxane"[tw] OR
"Silbione"[tw] OR "Octamethylcyclotetrasiloxan"[tw] OR"VS 7207"[tw] OR
"Cyclotetrasiloxane, octamethyl-"[tw] OR "Cyclic dimethylsiloxane
tetramer"[tw] OR "Dow Corning 344"[tw] OR "Volasil 244"[tw] OR "DC
244"[tw] OR "DC 344"[tw] OR "Octamethylcyclotetrasiloxanes"[tw])

259

Science
Direct

Search Date:
9/4/2020

1.	("Octamethylcyclotetrasiloxane" OR ("D4" AND "siloxane") OR "556-67-
2" OR "OMCTS" OR "cyclotetrasiloxane" OR "Silbione" OR
"Octamethylcyclotetrasiloxan")

2.	("VS 7207" OR "Cyclotetrasiloxane, octamethyl-" OR "Cyclic
dimethylsiloxane tetramer" OR "Dow Corning 344" OR "Volasil 244" OR
"DC 244" OR "DC 344" OR "Octamethylcyclotetrasiloxanes")

405

Page 72 of 124


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Source

Source-Specific Search Strategy

Results

ToxLine

Search Date:
9/4/2020

1.	ALL("Octamethylcyclotetrasiloxane" OR ("D4" AND "siloxane") OR "556-
67-2" OR "OMCTS" OR "cyclotetrasiloxane" OR "Silbione" OR
"Octamethylcyclotetrasiloxan" OR "VS 7207" OR "Cyclotetrasiloxane,
octamethyl-" OR "Cyclic dimethylsiloxane tetramer" OR "Dow Corning
344" OR "Volasil 244" OR "DC 244" OR "DC 344" OR
"Octamethylcyclotetrasiloxanes")

2.	tox [subset] AND ("Octamethylcyclotetrasiloxane"[tw] OR ("D4"[tw] AND
"siloxanes"[MeSH]) OR "556-67-2"[rn] OR "OMCTS"[tw] OR
"cyclotetrasiloxane"[tw] OR "Silbione"[tw] OR
"Octamethylcyclotetrasiloxan"[tw] OR"VS 7207"[tw] OR
"Cyclotetrasiloxane, octamethyl-"[tw] OR "Cyclic dimethylsiloxane
tetramer"[tw] OR "Dow Corning 344"[tw] OR "Volasil 244"[tw] OR "DC
244"[tw] OR "DC 344"[tw] OR "Octamethylcyclotetrasiloxanes"[tw])

197

WoS

Search Date:
9/4/2020

(TS="Octamethylcyclotetrasiloxane" OR (TS="D4" AND TS="siloxane") OR
TS="556-67-2" ORTS="OMCTS" OR TS="cyclotetrasiloxane" OR
TS="Silbione" OR TS="Octamethylcyclotetrasiloxan" OR TS="VS 7207" OR
TS="Cyclotetrasiloxane, octamethyl-" OR TS="Cyclic dimethylsiloxane
tetramer" OR TS="Dow Corning 344" OR TS="Volasil 244" OR TS="DC 244"
OR TS="DC 344" OR TS="Octamethylcyclotetrasiloxanes")

1,162

Total

Represents totals across all databases after deduplication.

1,533

Additional Strategies

Additional keywords have been searched to supplement the primary pool references. The supplemental
search was performed on four degradants during January 2021. These are the search terms used in the
supplemental search strategies for each of the databases listed below:

1.	Octamethyltetrasiloxanediol: Octamethyltetrasiloxanediol; 3081-07-0; 1,7-Tetrasiloxanediol,
1,1,3,3,5,5,7,7-octamethyl-; Octamethyltetrasiloxane-l,7-diol; Tetrasiloxane-l,7-diol,
1,1,3,3,5,5,7,7-octamethyl-

2.	Hexamethyltrisiloxanediol: Hexamethyltrisiloxanediol; 3663-50-1; 1,5-Trisiloxanediol,
1,1,3,3,5,5-hexamethyl-; Hexamethyltrisiloxane-1,5-diol

3.	Tetramethyldisiloxanediol: Tetramethyldisiloxanediol; 1118-15-6; Tetramethyldisiloxane-1,3-
diol; 1,3-Disiloxanediol, 1,1,3,3-tetramethyl-

4.	Dimethylsilanediol: Dimethylsilanediol; 1066-42-8; Dimethyldihydroxysilane;
Dihydroxydimethylsilane; Silanediol, dimethyl-

TableApx A-3. Summary of Supplemental Data Sources, Search Dates, and Number of Peer-
Reviewed Literature Search Results for Octamethylcyclotetrasiloxane (D4)		

Source

Source-Specific Search Strategy

Results

Agricola

Search Date:
1/13/2021

TIAB("Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-
Tetrasiloxanediol, 1,1,3,3,5,5,7,7-octamethyl-" OR "Octamethyltetrasiloxane-
1,7-diol" OR "Tetrasiloxane-l,7-diol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Hexamethyltrisiloxanediol" OR "3663-50-1" OR "1,5-Trisiloxanediol,
1,1,3,3,5,5-hexamethyl-" OR "Hexamethyltrisiloxane-l,5-diol" OR
"Tetramethyldisiloxanediol" OR "1118-15-6" OR "Tetramethyldisiloxane-1,3-
diol" OR "1,3-Disiloxanediol, 1,1,3,3-tetramethyl-" OR "Dimethylsilanediol"

0

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Source

Source-Specific Search Strategy

Results



OR "1066-42-8" OR "Dimethyldihydroxysilane" OR
"Dihydroxydimethylsilane" OR "Silanediol, dimethyl-")



Current
Contents

Search Date:
1/13/2021

TS=("Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-Tetrasiloxanediol,
1,1,3,3,5,5,7,7-octamethyl-" OR "Octamethyltetrasiloxane-l,7-diol" OR
"Tetrasiloxane-l,7-diol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Hexamethyltrisiloxanediol" OR "3663-50-1" OR "1,5-Trisiloxanediol,
1,1,3,3,5,5-hexamethyl-" OR "Hexamethyltrisiloxane-l,5-diol" OR
"Tetramethyldisiloxanediol" OR "1118-15-6" OR "Tetramethyldisiloxane-1,3-
diol" OR "1,3-Disiloxanediol, 1,1,3,3-tetramethyl-" OR "Dimethylsilanediol"
OR "1066-42-8" OR "Dimethyldihydroxysilane" OR
"Dihydroxydimethylsilane" OR "Silanediol, dimethyl-")

0

ProQuest
Dissertations
& Theses

Search Date:
1/13/2021

TIAB("Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-
Tetrasiloxanediol, 1,1,3,3,5,5,7,7-octamethyl-" OR "Octamethyltetrasiloxane-
1,7-diol" OR "Tetrasiloxane-l,7-diol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Hexamethyltrisiloxanediol" OR "3663-50-1" OR "1,5-Trisiloxanediol,
1,1,3,3,5,5-hexamethyl-" OR "Hexamethyltrisiloxane-l,5-diol" OR
"Tetramethyldisiloxanediol" OR "1118-15-6" OR "Tetramethyldisiloxane-1,3-
diol" OR "1,3-Disiloxanediol, 1,1,3,3-tetramethyl-" OR "Dimethylsilanediol"
OR "1066-42-8" OR "Dimethyldihydroxysilane" OR
"Dihydroxydimethylsilane" OR "Silanediol, dimethyl-")

0

ProQuest
Agricultural
& Scientific
Database

Search Date:
1/13/2021

TIAB("Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-
Tetrasiloxanediol, 1,1,3,3,5,5,7,7-octamethyl-" OR "Octamethyltetrasiloxane-
1,7-diol" OR "Tetrasiloxane-l,7-diol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Hexamethyltrisiloxanediol" OR "3663-50-1" OR "1,5-Trisiloxanediol,
1,1,3,3,5,5-hexamethyl-" OR "Hexamethyltrisiloxane-l,5-diol" OR
"Tetramethyldisiloxanediol" OR "1118-15-6" OR "Tetramethyldisiloxane-1,3-
diol" OR "1,3-Disiloxanediol, 1,1,3,3-tetramethyl-" OR "Dimethylsilanediol"
OR "1066-42-8" OR "Dimethyldihydroxysilane" OR
"Dihydroxydimethylsilane" OR "Silanediol, dimethyl-")

48

PubMed

Search Date:
1/13/2021

"Octamethyltetrasiloxanediol"[tw] OR "3081-07-0"[rn] OR "1,7-
Tetrasiloxanediol, l,l,3,3,5,5,7,7-octamethyl-"[tw] OR
"Octamethyltetrasiloxane-l,7-diol"[tw] OR "Tetrasiloxane-l,7-diol,
l,l,3,3,5,5,7,7-octamethyl-"[tw] OR "Hexamethyltrisiloxanediol"[tw] OR
"3663-50-l"[rn] OR "1,5-Trisiloxanediol, l,l,3,3,5,5-hexamethyl-"[tw] OR
"Hexamethyltrisiloxane-l,5-diol"[tw] OR "Tetramethyldisiloxanediol"[tw] OR
"1118-15-6"[rn] OR "Tetramethyldisiloxane-l,3-diol"[tw] OR "1,3-
Disiloxanediol, l,l,3,3-tetramethyl-"[tw] OR "Dimethylsilanediol"[tw] OR
"1066-42-8"[rn] OR "Dimethyldihydroxysilane"[tw] OR
"Dihydroxydimethylsilane"[tw] OR "Silanediol, dimethyl-"[tw]

22

Science
Direct

Search Date:
1/13/2021

1.	"Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-Tetrasiloxanediol,
1,1,3,3,5,5,7,7-octamethyl-" OR "Octamethyltetrasiloxane-l,7-diol" OR
"Tetrasiloxane-l,7-diol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Hexamethyltrisiloxanediol" OR "3663-50-1"

2.	"1,5-Trisiloxanediol, 1,1,3,3,5,5-hexamethyl-" OR "Hexamethyltrisiloxane-
1,5-diol" OR "Tetramethyldisiloxanediol" OR "1118-15-6" OR
"Tetramethyldisiloxane-l,3-diol" OR "1,3-Disiloxanediol, 1,1,3,3-
tetramethyl-" OR "Dimethylsilanediol" OR "1066-42-8"

3.	"Dimethyldihydroxysilane" OR "Dihydroxydimethylsilane" OR "Silanediol,
dimethyl-"

0

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Source

Source-Specific Search Strategy

Results

ToxLine

Search Date:
1/13/2021

1.	TIAB("Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-
Tetrasiloxanediol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Octamethyltetrasiloxane-l,7-diol" OR "Tetrasiloxane-l,7-diol,
1,1,3,3,5,5,7,7-octamethyl-" OR "Hexamethyltrisiloxanediol" OR "3663-50-
1" OR "1,5-Trisiloxanediol, 1,1,3,3,5,5-hexamethyl-" OR
"Hexamethyltrisiloxane-l,5-diol" OR "Tetramethyldisiloxanediol" OR

"1118-15-6" OR "Tetramethyldisiloxane-l,3-diol" OR "1,3-Disiloxanediol,
1,1,3,3-tetramethyl-" OR "Dimethylsilanediol" OR "1066-42-8" OR
"Dimethyldihydroxysilane" OR "Dihydroxydimethylsilane" OR "Silanediol,
dimethyl-")

2.	tox[subset] AND ("Octamethyltetrasiloxanediol"[tw] OR "3081-07-0"[rn]
OR "1,7-Tetrasiloxanediol, l,l,3,3,5,5,7,7-octamethyl-"[tw] OR
"Octamethyltetrasiloxane-l,7-diol"[tw] OR "Tetrasiloxane-l,7-diol,
l,l,3,3,5,5,7,7-octamethyl-"[tw] OR "Hexamethyltrisiloxanediol"[tw] OR
"3663-50-l"[rn] OR "1,5-Trisiloxanediol, l,l,3,3,5,5-hexamethyl-"[tw] OR
"Hexamethyltrisiloxane-l,5-diol"[tw] OR "Tetramethyldisiloxanediol"[tw]
OR "1118-15-6"[rn] OR "Tetramethyldisiloxane-l,3-diol"[tw] OR "1,3-
Disiloxanediol, l,l,3,3-tetramethyl-"[tw] OR "Dimethylsilanediol"[tw] OR
"1066-42-8"[rn] OR "Dimethyldihydroxysilane"[tw] OR
"Dihydroxydimethylsilane"[tw] OR "Silanediol, dimethyl-"[tw])

10

WoS

Search Date:
1/13/2021

TS=("Octamethyltetrasiloxanediol" OR "3081-07-0" OR "1,7-Tetrasiloxanediol,
1,1,3,3,5,5,7,7-octamethyl-" OR "Octamethyltetrasiloxane-l,7-diol" OR
"Tetrasiloxane-l,7-diol, 1,1,3,3,5,5,7,7-octamethyl-" OR
"Hexamethyltrisiloxanediol" OR "3663-50-1" OR "1,5-Trisiloxanediol,
1,1,3,3,5,5-hexamethyl-" OR "Hexamethyltrisiloxane-l,5-diol" OR
"Tetramethyldisiloxanediol" OR "1118-15-6" OR "Tetramethyldisiloxane-1,3-
diol" OR "1,3-Disiloxanediol, 1,1,3,3-tetramethyl-" OR "Dimethylsilanediol"
OR "1066-42-8" OR "Dimethyldihydroxysilane" OR
"Dihydroxydimethylsilane" OR "Silanediol, dimethyl-")

79

Total

Represents totals across all databases after deduplication.

96

A. 1.2,2 Data Prioritization for Environmental Hazard, Human Health Hazard, Fate,
and Physical Chemistry

In brief, SWIFT Review has pre-set literature search strategies ("filters") developed by information
specialists that can be applied to identify studies that are more likely to be useful for identifying human
health and ecotoxicity content from those that likely do not (e.g., analytical methods). The filters
function like a typical search strategy where studies are tagged as belonging to a certain filter if the
terms in the filter literature search strategy appear in title, abstract, keyword, or medical subject headings
(MeSH) fields content. The applied SWIFT Review filters focused on the following lines of evidence:
human, animal models for human health, ecological taxa (which includes ecotoxicological animal
models, plants, and other taxa), and in vitro studies. The details of the search strategies that underlie the
filters are available online. Studies not retrieved using these filters were not considered further. Studies
that included one or more of the search terms in the title, abstract, keyword, or MeSH fields were
exported as a RIS file for screening in Sv IveScreener or DistillerSR.9

9 DistillerSR is a web-based systematic review software used to screen studies.

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A. 1.2.3 Data Prioritization for Occupational Exposures and Environmental Releases
and Gen Pop, Consumer, and Environmental Exposures

To prioritize references related to occupational exposure, environmental release, general population
exposure, consumer exposure, and environmental exposure, EPA used positive and negative seed studies
to build a classification model in SWIFT Review. The positive seeds were identified using relevant
literature pool for the first 10 TSCA risk evaluations, while the negative seeds were identified from a
subset of literature for the current high-priority substances. The model was then applied to the
unclassified literature to generate a classification score for each reference. Scores above a certain
threshold value were then prioritized for further review in SW1 tiveScreener.

A.2 Peer-Reviewed Screening Process

The studies identified from publicly available database searches and SWIFT-Review
filtering/prioritization were housed in HERO system and imported into SWIFT-ActiveScreener or
DistillerSR for title/abstract and full-text screening. Both title/abstract and full-text screening were
conducted by two independent reviewers. Screening is initiated with a pilot phase of screening (between
10 and 50) studies to identify areas where clarification in screening criteria might be needed or
chemical-specific supplemental material tags might be identified. Records that met PECO (or equivalent
criteria (Appendix A.2.1) during title and abstract screening were considered for full-text screening. At
both the title/abstract and full-text review levels, screening conflicts were resolved by topic-specific
experts and/or discussion among the primary screeners. For citations with no abstract, the articles are
initially screened based on all or some of the following: title relevance (titles that suggest a record is not
relevant can be excluded rather than marked as unclear), and page numbers (articles two pages in length
or less were assumed to be conference reports, editorials, or letters). During title/abstract or full-text
level screening in DistillerSR, studies that did not meet the PECO criteria, but which could provide
supporting information, were categorized (or "tagged") as supplemental information.

It is important to emphasize that being tagged as supplemental material does not mean the study would
necessarily be excluded from consideration in an assessment. The initial screening level distinctions
between a study meeting the PECO criteria and a supplemental study are often made for practical
reasons and the tagging structures (as seen in the literature inventory trees and heat maps in Section 2.1
of this document) are designed to ensure the supplemental studies are categorized for easy retrieval if
needed while conducting the assessment. The impact on the assessment conclusions of individual studies
tagged as supporting material is often difficult to assess during the screening phase of the assessment.
These studies may emerge as being critically important to the assessment and need to be evaluated and
summarized at the individual study level (e.g., cancer MOA mechanistic or non-English-language
studies), or be helpful to provide context (e.g., summarize current levels of exposure, provide hazard
evidence from routes or durations of exposure not pertinent to the PECO), or not be cited at all in the
assessment (e.g., individual studies that contribute to a well-established scientific conclusion). Studies
maybe be tagged as supplemental material during either title and abstract or full-text screening. When
tagged as supplemental material during title and abstract screening, it may not be completely clear
whether the chemical of interest is reported in the study (i.e., abstracts may not describe all chemicals
investigated). In these cases, studies are still tagged with the expectation that if full-text retrieval is
pursued, then additional screening would be needed to clarify if the study is pertinent.

A.2.1 Inclusion/Exclusion Criteria

A PECO statement is typically used to focus the research question(s), search terms, and
inclusion/exclusion criteria in a systematic review. PECO criteria were developed a priori to screening
and modified to fit the various discipline areas supporting the TSCA risk evaluations. Variations include
the RESO (receptor, exposure, scenario/setting, and outcome) used for the occupational exposure and

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environmental releases discipline, and PESO (pathways/processes, exposures, setting/scenario, and
outcomes) used by the fate and transport discipline. All PECOs and PECO-equivalent criteria can be
found in the following sections.

A.2.1.1 PECO for Environmental and Human Health Hazards

The PECO used in this evidence map to identify literature pertinent to D4 effects on human health and
environmental hazard is presented in TableApx A-4. In addition to the PECO criteria, studies
containing potentially relevant supplemental material were tracked and categorized during the literature
screening process as outlined in Table Apx A-5.

Table Apx A-4. Hazards Title and Abstract and Full-Text PECO Criteria for D4

PECO Element

Evidence

Population

	Human: Any population and life stage (e.g., occupational or general population,
including children and other sensitive populations).

	Animal: Aquatic and terrestrial species (live, whole organism) from any life stage
(e.g., preconception, inutero, lactation, peripubertal, and adult stages). Animal
models will be inventoried according to the categorization below:

-	Human health models: rat. mouse, rabbit, doe. hamster, euinea Die. cat. non-
human primate, pig, hen (neurotoxicity only)

-	Ecotoxicoloeical models: invertebrates (e.s.. insects, soidcrs. crustaceans,
mollusks, and worms) and vertebrates (e.g., mammals and all amphibians, birds,
fish, and reptiles). All hen studies (including neurotoxicity studies) will be
included for ecotoxicological models.

	Plants: All aquatic and terrestrial species (live), including algal, moss, lichen, and
fungi species.

Screener notes:

	To identify human health and environmental hazards, other organisms not listed
above in their respective categories can also be used. Non-mammalian model
systems are increasingly used to identify potential human health hazards (e.g.,
Xenopus, zebrafish), and traditional human health models (e.g., rodents) can be used
to identify potential environmental hazard. Neurotoxicity studies performed in hens
(e.g., OECD 418 and 419) are considered relevant to both human and eco hazard

	PECO considerations should be directed toward effects on target species only and
not on the indirect effects expressed in taxa as a result of chemical treatment (e.g.,
substance is lethal to a targeted pest species leading to positive effects on plant
growth due to diminished presence of the targeted pest species).

	Tests of the single toxicants in in vitro and ex vivo systems or on gametes, embryos,
or plant or fungal sections capable of forming whole, new organisms will be tagged
as potentially supplemental (mechanistic studies). Bacteria and yeast studies specific
for assessing genotoxicity or mutagenicity (e.g., Ames assay) will also be tagged as
potentially supplemental (mechanistic studies) but are otherwise excluded. Studies
on viruses are excluded.

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PECO Element

Evidence

Exposure

Relevant forms and isomers:

Octamethylcyclotetrasiloxane (D4); CASRN: 556-67-2

	No isomers were included for D4

For svnonvms see a list of validated svnonvms on the EPA Chemistrv Dashboard

	Human: Any exposure to Octamethylcyclotetrasiloxane (D4); CASRN: 556-67-2
singularly or in mixture, including exposure as measured by internal concentrations
of these chemicals or metabolites of these chemicals in a biological matrix (i.e.,
urine, blood, semen, etc.).

	Animal: Any exposure to Octamethylcyclotetrasiloxane (D4); CASRN: 556-67-2
including via water (including environmental aquatic exposures), soil or sediment,
diet, gavage, injection, dermal, and inhalation.

	Plants: Any exposure to Octamethylcyclotetrasiloxane (D4); CASRN: 556-67-2
including via water, soil, sediment.

Screener notes:

	Field studies with media concentrations (e.g., surface water, interstitial water, soil,
sediment) and/or body/tissue concentrations of animals or plants are to be identified
as Supplemental if anv biolosical effects are reported.

	Studies involving exposures to mixtures will be included only if they also include
exposure to Octamethylcyclotetrasiloxane (D4); CASRN: 556-67-2 alone.
Otherwise, mixture studies will be tassed as Supplemental.

	Controlled outdoor experimental studies (e.g., controlled crop/greenhouse studies,
mesocosm studies, artificial stream studies) are considered to be laboratory studies
(not field studies) because there is a known and prescribed exposure dose(s) and an
evaluation of hazardous effect(s). Whereas field studies (e.g., biomonitoring) where
there is no prescribed exposure dose(s) will be excluded if there is no evaluated
hazardous effect, and tagged as supplemental field, if there is an evaluated
hazardous effect.

	D4 degradants (4) and other relevant siloxane structures (6) are also identified and
should be tagged as supplemental if PECO-relevant.

Comparator

	Human: A comparison or referent population exposed to lower levels (or no
exposure/exposure below detection limits) of Octamethylcyclotetrasiloxane (D4);
CASRN: 556-67-2, or exposure to Octamethylcyclotetrasiloxane (D4); CASRN:
556-67-2 for shorter periods of time.

	Animal and Plants: A concurrent control group exposed to vehicle-only treatment
and/or untreated control (control could be a baseline measurement).

Screener notes:

	If no control group is explicitly stated or implied (e.g., by mention of statistical
results that could only be obtained if a control group was present), the study will be
marked as Unclear durine Title/Abstract Screening.

	All case series and case reports describing findings in a sample size of less than 20
people in any setting (e.g., occupation, general population) will be tracked as

Supplemental.

	Case-control, case-crossover, case-referent, case-only, case-specular, case-cohort,
case-oarent, cross sectional, nested case-control studv desiens are all Included.

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PECO Element

Evidence

Outcomes

	Human: All health outcomes (cancer and non-cancer) at the organ level or higher.

	Animal and Plants: All apical biological effects (effects measured at the organ
level or higher) and bioaccumulation from laboratory studies with concurrently
measured media and/or tissue concentrations). Apical endpoints include but are not
limited to reproduction, survival, and growth.

Screener notes:

	Measurable biological effects relevant for humans, animals and plants may include
but are not limited to mortality, behavioral, population, cellular, physiological,
growth, reproduction, systemic, point of contact (irritation and sensitization) effects.

	Effects measured at the cellular level of biological organization and below are to be
tagged as supplemental, mechanistic.

Table Apx A-5. Major Categories of "Potentially Relevant" Supplemental Materials for D4

Category

Evidence

Mechanistic studies

All studies that report results at the cellular level and lower in both
mammalian and non-mammalian model systems, including in vitro, in
vivo, ex vivo, and in silico studies. These studies include assays for
genotoxicity or mutagenicity using bacteria or yeast.

ADME, PBPK, and
toxicokinetic

Studies designed to capture information regarding ADME, toxicokinetic
studies, or PBPK models.

Case reports or
case series

Case reports (n < 3 cases) and case series (non-occupational) will be
tracked as potentially relevant supplemental information.

Potentially exposed
or susceptible
subpopulations
(no health outcome)

Studies that identify potentially susceptible subgroups; for example,
studies that focus on a specific demographic, life stage, or genotype. This
tag applies primarily during full-text screening.

Screener note: If biological susceptibility issues are clearly present or
strongly implied in the title/abstract, this supplemental tag may be applied
at the title abstract level. If uncertain at title/abstract, do not apply this tag
to the reference during title/abstract screening.

Mixture studies

Experimental mixture studies that are not considered PECO-relevant
because they do not contain an exposure or treatment group assessing only
the chemical of interest. Human health animal model and environmental
animal model/plant will be tagged separately for mixture studies.

Records with no
original data

Records that do not contain original data, such as other agency
assessments, informative scientific literature reviews, editorials, or
commentaries.

Conference
abstracts

Records that do not contain sufficient documentation to support study
evaluation and data extraction.

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Category

Evidence

Non-English
records

Non-English records will be tracked as potentially relevant supplemental
information.

Field studies

Field studies with media concentrations (e.g., surface water, interstitial
water, soil, sediment) and/or body/tissue concentrations of animals or
plants if biological effects reported.

Other relevant
chemical structures

PECO-relevant studies with other chemical structures such as metabolites
or degradants that may be useful later. For example, identified degradants
for D4 include octamethyltetrasiloxanediol (CASRN 3081-07-0),
hexamethyltrisiloxanediol (CASRN 3663-50-1), tetramethyldisiloxanediol
(CASRN 1118-15-6), and dimethylsilanediol (CASRN 1066-42-8).

In addition, six other relevant siloxane structures should also be tagged as
supplemental: octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4),
dodecamethylpentasiloxane (L5), hexamethylcyclotrisiloxane (D3),
decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane
(D6).

A.2.1.2 PECO for Consumer, Environmental, and General Population Exposures

Table Apx A-6. Generic Inclusion Criteria for the Data Sources Reporting Exposure Data on
General Population, Consumers, and Environmental Receptors	

PECO Element

Evidence

Population

Human: General population; consumers; bystanders in the home; near-facilitv
populations (includes industrial and commercial facilities manufacturing, processing,
or using the chemical substance); children; susceptible populations (life stages,
preexisting conditions, genetic factors), pregnant women; lactating women, women of
child-bearing age. Many human population groups may be exposed. No chemical-
specific exclusions are suggested at this time.

Environmental: Aauatic species. terrestrial species. terrestrial plants, aauatic plants
(field studies only)

Exposure

Expected Primary Exposure Sources, Pathways, Routes:

Pathways: indoor air/vapor/mist; indoor dust; particles; outdoor/ambient air; surface
water; biosolids; sediment; human milk; food items containing D4 including fish;
consumer product uses in the home (including consumer product containing chemical)

Routes of Exposure: Inhalation. Oral. Dermal

Comparator
(Scenario)

Human: Consider media-specific background exposure scenarios and use/source
specific exposure scenarios as well as which receptors are and are not reasonably
exposed across the projected exposure scenarios.

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PECO Element

Evidence



Environmental: Consider media-specific background exposure scenarios and
use/source specific exposure scenarios as well as which receptors are and are not
reasonably exposed across the projected exposure scenarios.

Outcomes for
Exposure
Concentration or
Dose

Human: Acute, subchronic. and/or indoor air and water concentration estimates
(mg/m3 or mg/L). Both external potential dose and internal dose based on
biomonitoring and reverse dosimetry mg/kg/day will be considered. Characteristics of
consumer products or articles (weight fraction, emission rates, etc) containing D4.

Environmental: A wide ranse of ecoloaical receptors will be considered (ranse
depending on available ecotoxicity data) using surface water concentrations, sediment
concentrations.

A.2.1.3 RI SC) for Occupational Kxposure and Environmental Releases

EPA developed a generic RESO statement to guide the screening of engineering and occupational
exposure data or information sources for the TSCA risk evaluations. Data or information sources that
comply with the inclusion criteria specified in the RESO statement are eligible for inclusion, considered
for evaluation, and possibly included in the environmental release and occupational exposure
assessments. On the other hand, data or information sources that fail to meet the criteria in the RESO
statement are excluded from further consideration.

Assessors seek information on various chemical-specific engineering and occupational exposure data
needs as part of the process of developing the exposure assessment for each risk evaluation. EPA uses
the RESO statement (TableApx A-7) along with the information in TableApx A-8 when screening the
engineering and occupational exposure data and information.

Table Apx A-7. Inclusion Criteria for Data Sources Reporting Engineering and Occupational
Exposure Data	

RESO
Element

Evidence

Receptors

	Humans:

Workers, including ONUs

	Environment:

All environmental receptors (relevant release estimates input to Exposure)

Please refer to the conceptual models for more information about the environmental and
human receptors included in the TSCA risk evaluation.

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RESO
Element

Evidence

Exposure

 Worker exposure to and relevant environmental releases of the chemical substance from
occupational scenarios:

Dermal and inhalation exposure routes (as indicated in the conceptual model)

Oral route (as indicated in the conceptual model)

Please refer to the conceptual models for more information about the routes and
media/pathways included in the TSCA risk evaluation.

Setting or
Scenario

 Any occupational setting or scenario resulting in worker exposure and relevant
environmental releases (includes all manufacturing, processing, use, disposal).

Outcomes

	Quantitative estimates" of worker exposures and of relevant environmental releases from
occupational settings

	General information and data related and relevant to the occupational estimates"

a Metrics (e.g., mg/kg/day or mg/m3 for worker exposures, kg/site/day for releases) are determined by toxicologists
for worker exposures and by exposure assessors for releases; also, the Engineering, Release, and Occupational
Exposure Data Needs (Table Apx A-8) provides a list of related and relevant general information.

TableApx A-8. Engineering, Environmental Release, and Occupational Data Necessary to
Develop the Environmental Release and Occupational Exposure Assessments	

Objective Determined
during Scoping

Type of Data"

General Engineering
Assessment (may apply to
Occupational Exposures
and/or Environmental
Releases)

Description of the life cycle of the chemical(s) of interest, from manufacture to end-of-life
(e.g., each manufacturing, processing, or use step), and material flow between the
industrial and commercial life cycle stages.

The total annual U.S. volume (lb/yr or kg/yr) of the chemical(s) of interest manufactured,
imported, processed, and used; and the share of total annual manufacturing and import
volume that is processed or used in each life cycle step.

Description of processes, equipment, and unit operations during each industrial/ commercial
life cycle step.

Material flows, use rates, and frequencies (lb/site-day or kg/site-day and days/yr; lb/site-
batch and batches/yr) of the chemical(s) of interest during each industrial/ commercial life
cycle step. Note: if available, include weight fractions of the chemicals (s) of interest and
material flows of all associated primary chemicals (especially water).

Number of sites that manufacture, process, or use the chemical(s) of interest for each
industrial/ commercial life cycle step and site locations.

Concentration of the chemical of interest

Occupational Exposures

Description of worker activities with exposure potential during the manufacture, processing,
or use of the chemical(s) of interest in each industrial/commercial life cycle stage.

Potential routes of exposure (e.g., inhalation, dermal).

Physical form of the chemical(s) of interest for each exposure route (e.g., liquid, vapor, mist)
and activity.

Breathing zone (personal sample) measurements of occupational exposures to the chemical(s)
of interest, measured as time-weighted averages (TWAs), short-term exposures, or peak
exposures in each occupational life cycle stage (or in a workplace scenario similar to an
occupational life cycle stage).

Page 82 of 124


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Objective Determined
during Scoping

Type of Data"



Area or stationary measurements of airborne concentrations of the chemical(s) of interest in
each occupational setting and life cycle stage (or in a workplace scenario similar to the life
cycle stage of interest).

For solids, bulk and dust particle size characterization data.

Dermal exposure data.

Exposure duration (hr/day).

Exposure frequency (days/yr).

Number of workers who potentially handle or have exposure to the chemical(s) of interest in
each occupational life cycle stage.

PPE types employed by the industries within scope.

Engineering Controls employed to reduce occupational exposures in each occupational life
cycle stage (or in a workplace scenario similar to the life cycle stage of interest), and
associated data or estimates of exposure reductions.

Environmental Releases
(to relevant environmental
media)

Description of sources of potential environmental releases, including cleaning of residues
from process equipment and transport containers, involved during the manufacture,
processing, or use of the chemical(s) of interest in each life cycle stage.

Estimated mass (lb or kg) of the chemical(s) of interest released from industrial and
commercial sites to each environmental medium (water) and treatment and disposal
methods (POTW), including releases per site and aggregated over all sites (annual release
rates, daily release rates)

Release or emission factors.

Number of release days per year.

Waste treatment methods and pollution control devices employed by the industries within
scope and associated data on release/emission reductions.

In addition to the data types listed above, EPA may identify additional data needs for mathematical modeling. These data
needs will be determined on a case-by-case basis.

" These are the tags included in the full-text screening form. The screener makes a selection from these specific tags, which
describe more specific types of data or information.

A.2.1.4 PESO for Fate and Transport

EPA developed a generic PESO statement to guide the screening of environmental fate data or
information sources for the TSCA risk evaluations. Data or information sources that comply with the
inclusion criteria in the PESO statement are eligible for inclusion, considered for evaluation, and
possibly included in the environmental fate assessment. On the other hand, data or information sources
that fail to meet the criteria in the PESO statement are excluded from further consideration.

Assessors seek information on various chemical-specific fate endpoints and associated fate processes,
environmental media, and exposure pathways as part of the process of developing the environmental
fate assessment for each risk evaluation. EPA uses the PESO statement (Table Apx A-9) along with the
information in

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TableApx A-10 when screening the fate data or information sources to ensure complete coverage of the
processes, pathways, and data or information relevant to the environmental fate and transport of the
chemical substance undergoing risk evaluation.

Table Apx A-9. Inclusion Criteria for Data or Information Sources Reporting Environmental
Fate and Transport Data		

PESO
Element

Evidence

Pathways and Processes

Environmental fate, transport, partitioning and degradation behavior
across environmental media to inform exposure pathways of the
chemical category of interest
Exposure pathways included in the conceptual models: air, surface water,

groundwater, wastewater, soil, sediment and biosolids.

Processes associated with the target exposure pathways
Bioconcentration and bioaccumulation
Destruction and removal by incineration

Please refer to the conceptual models for more information about the
exposure pathways included in each TSCA risk evaluation.

Exposure

Environmental exposure of environmental receptors (i.e., aquatic and
terrestrial organisms) to the chemical substance of interest, mixtures
including the chemical substance, and/or its degradation products and
metabolites

Environmental exposure of human receptors, including any PESS, to the
chemical substance of interest, mixtures including the chemical
substance, and/or its degradation products and metabolites

Please refer to the conceptual models for more information about the
environmental and human receptors included in each TSCA risk
evaluation.

Setting or Scenario

Any setting or scenario resulting in releases of the chemical substance of
interest into the natural or built environment (e.g., buildings including
homes or workplaces, or wastewater treatment facilities) that would
expose environmental (i.e., aquatic and terrestrial organisms) or
human receptors (i.e., general population and PESS)

Outcomes

Fate properties which allow assessments of exposure pathways:

Abiotic and biotic degradation rates, mechanisms, pathways, and
products

Bioaccumulation magnitude and metabolism rates
Partitioning within and between environmental media (see Pathways and
Processes)

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TableApx A-10. Fate Endpoints and Associated Processes, Media, and Exposure Pathways
Considered in the Development of the Environmental Fate Assessment	

Fate Data Endpoint

Associated Process(cs)

Associated Media/Exposure Pathways

Surface
Water,
Wastewater,
Sediment

Soil,
Biosolids

Groundwater

Air

Required cn\ imiinicuial laic data

Abiotic reduction rates or half-
lives

Abiotic reduction, Abiotic
dehalogenation

X







Aerobic biodegradation rates or
half-lives

Aerobic biodegradation

X

X





Anaerobic biodegradation rates
or half-lives

Anaerobic biodegradation

X

X

X



Aqueous photolysis (direct and
indirect) rates or half-lives

Aqueous photolysis (direct
and indirect)

X







Atmospheric photolysis (direct
and indirect) rates or half-lives

Atmospheric photolysis
(direct and indirect)







X

Bioconcentration factor (BCF),
Bioaccumulation factor (B AF)

Bioconcentration,
Bioaccumulation

X

X



X

Biomagnification and related
information

Trophic magnification

X







Desorption information

Sorption, Mobility

X

X

X



Destruction and removal by
incineration

Incineration







X

Hydrolysis rates or half-lives

Hydrolysis

X

X

X



Koc and other sorption
information

Sorption, Mobility

X

X

X



Wastewater treatment removal
information

Wastewater treatment

X

X





Supplemental (or optional i en\ immuciilal laic dula

Abiotic transformation
products

Hydrolysis, Photolysis,
Incineration

X





X

Aerobic biotransformation
products

Aerobic biodegradation

X

X





Anaerobic biotransformation
products

Anaerobic biodegradation

X

X

X



Atmospheric deposition
information

Atmospheric deposition







X

Page 85 of 124


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Fate Data Endpoint

Associated Process(cs)

Associated Media/Exposure Pathways

Surface
Water,
Wastewater,
Sediment

Soil,
Biosolids

Groundwater

Air

Coagulation information

Coagulation, Mobility

X



X



Incineration removal
information

Incineration







X

A.2.1.5 Generation of Hazard Heat Maps

As stated in Appendix A. 1.2.2, SWIFT Review has pre-set literature search strategies ("filters")
developed by information specialists that can be applied to identify studies that are more likely to be
useful for identifying human health and ecotoxicity content. The filters function like a typical search
strategy where studies are tagged as belonging to a certain filter if the terms in the filter literature search
strategy appear in title, abstract, keyword, or MeSH fields content.

After the completion of full-text screening for hazard data, all references tagged as included (or "PECO-
relevant") were uploaded to the SWIFT Review tool for further filtering. The SWIFT Review filters
applied at this phase focused on types of health outcomes included the following: "ADME," "PBPK,"
"cancer," "cardiovascular," "developmental," "endocrine," "gastrointestinal," "hematological and
immune," "hepatic," "mortality," "musculoskeletal," "neurological," "nutritional and metabolic,"
"ocular and sensory," "renal," "reproductive," "respiratory," and "skin and connective tissue.". The
details of these health outcome search strategies that underlie the filters are available online. Studies that
included one or more of the search terms in the title, abstract, keyword, or MeSH fields were exported
and used to populate the Hazard Heat Map (Figure 2-10). Studies that were not retrieved using these
filters were tagged as "No Tag." The evidence type listed in the heat map (e.g., human, animal-human
health model, animal-environmental model, plant) was manually assigned to each reference by screeners
during the full-text screening.

The health outcome tags were originally designed for vertebrate systems, and as such, did not conform
well to plant evidence. Therefore, any plant studies tagged for "cancer," "cardiovascular,"
"gastrointestinal," "hematological and immune," "hepatic," "musculoskeletal," "neurological," "ocular
and sensory" and "renal and respiratory" were manually reviewed and re-tagged to more appropriate
health outcomes.

A.3 Gray Literature Search and Screening Strategies

EPA conducted a gray literature search for reasonably available information to support the manufacturer
requested TSCA risk evaluation for D4. Gray literature is defined as the broad category of
data/information sources not found in standard, peer-reviewed literature databases (e.g., PubMed and
Web of Science). Gray literature includes data/information sources such as white papers, conference
proceedings, technical reports, reference books, dissertations, information on various stakeholder
websites, and other databases. Given the nature of how gray literature is searched and collected, results
may not come with a bibliographic citation or abstract and were therefore processed using a decision
tree logic described in Appendix A.3.1 for potential relevance prior to entering full-text screening where
a discipline-specific PECO is applied.

Search terms were variable dependent on source and based on knowledge of a given source to provide

Page 86 of 124


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discipline-specific information. A summary of sources is provided in Appendix A.3.4. The criteria for
determining the potential relevance of documents identified from gray literature sources is described in
the following sections for each discipline.

A.3.1 Screening of Gray Literature

To reduce the overall burden of processing gray literature results, EPA developed a screening process to
determine the potential relevance of gray literature. This step was introduced prior to collecting the
resulting documents. Figure Apx A-l describes the decision logic used to screen gray literature results.

Page 87 of 124


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Gray Literature
Search Results

Step 1: Relevancy

1. Doss the result have information
(quantitative or qualitative) related
to TSCA risk evaluations'^

No

<

Exclude

J

Yes

Add to
Peer Review
Process

Step 2: Completenes^Availability

No

No

2.1.1. Is it a secondary result (e.g..
assessment, robust summary)"1

Yes

Process Bios

Caught in Peer
Review Search;

Yes

2.1.2. Is the result in a peer
reviewed/published journal?

Yes

/ Exclude

\ Duplicate ofPeer-
\ Reviewed Result

No

2.2. Is there an
established procedure for
data collection
communication, peer
review and or reporting?

Yes

2.3. Is the result publicly
available or accessible?

No

f

N

2.3.1. Is the

result CBI.

proprietary, TSCA or NGO

stakeholder' submission?

V

J



No



r

2.2.1. Has the result been

produced by a US

government.1 state source?



No

1

f



\

2.2.2. Has the result been

produced by an international

government source?

v

J

Yes

Process C

Follow the procedure for
incorporating TSCA,
FTFRA, NGO or other
stakeholder submissions
(including CBI.
proprietary studies, robust
summaries)

Yes

Process A
Follow the procedure for
US government result
validation

Yes

Yes

Legend

Included
Excluded
I EPA task
Third partytasks
Third partyproces j tin
Wwfc	I

Step5: Deduplication

No

Process B

Follow the procedure for
international government
result validation

No

r

Decision

Step

f Screening terminator ~'j

3. Does the result contain
duplicative information with
other results?

Step 4: EPA Secondary
Screening

Yes

Yes

Deduplicate

<

Include

>

EPA QC- Include

FigureApx A-l. Decision Logic Tree Used to Screen Gray Literature Results

A.3.2 Initial Screening of Sources Using Decision Logic Tree

The purpose of the inclusion/exclusion decision logic tree in FigureApx A-l is to provide a broad,
general screening technique to determine whether each gray literature source should be included and
further screened or excluded with no additional screening necessary. The diamonds in the decision tree
require analysis by the screener, whereas the rectangular boxes are used to classify the type of source.
All the questions used in the decision process are provided in Table Apx A-l 1.

Page 88 of 124


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Table ApxA-1]

. Decision Logic Tree C

~verview

Step

Metric

Questions to Consider

1

Potential Relevance

Does the result have information (qualitative or
quantitative) related to TSCA risk evaluations?"

2.1.1

Complete/available

Is it a secondary data source (assessment, robust summary,
TSCA submission databases, etc.)?

2.1.2

Is the document from a peer-reviewed/published journal?

2.2

Is there an established procedure for data collection,
communication, peer review, and/or reporting?

2.2.1

Has the data been provided by a US governmental/state
source?

2.2.2

Has the data been provided by an international
governmental source?

2.3

Are these data publicly available/accessible?

2.3.1

Is the source TSCA CBI, proprietary, TSCA, or NGO
stakeholder submission?

3

Duplicate

Does the result contain any duplicative information found in
other sources?

a Apply discipline relevancy metric

Results of the gray literature search and decision tree process are included in Appendix A.3.3.

A.3.3 TSCA Submission Searching and Title Screening

EPA screens information submitted under TSCA sections 4, 5, 8(e), and 8(d), as well as for your
information (FYI) submissions. In the gray literature process defined in Appendix A.3.2, EPA considers
the databases that contain TSCA submissions to be secondary sources (Step 1.1) because the metadata in
the databases are secondary. These databases then advance to Step 2.3.1 and then to Process C. The
Process C steps are described here.

EPA first screens the titles using two screeners per title. EPA conducts this step primarily to reduce the
number of full studies to be obtained because some studies are available only on microfiche or in long-
term storage. Screening is done using the inclusion and exclusion criteria within the relevant PECOs,
PESOs or RESOs for each topic area (Appendix A.2.1). EPA excludes interim reports (e.g., interim
sacrifices for toxicity studies) and only final reports are further considered. If the title is not clear
regarding the document's contents, EPA obtains the full-text and advances to the next steps.

After full texts are obtained, EPA reviews some sources (prior to full-text screening) based on whether
they have several factors: primary data, an established procedure for peer review, data collection,
communication and/or reporting, and are publicly available. Sources that have these factors will move

Page 89 of 124


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on to full-text screening. Other sources will go straight to full-text screening using PECO-type criteria
without going through this extra step.

EPA may decide to initiate a backwards search on sources that are deemed to have secondary data. In
situations where parameters such as procedures for peer review and data collection are unclear, EPA
may reach out to the authors to retrieve information to gauge whether the source should be included or
excluded. Studies that are not publicly available (such as proprietary or CBI sources) may undergo
additional screening steps.

During the full-text screening step, two individuals screen each source according to the PECOs, PESOs,
and RESOs (Appendix A.2.1).

Results of the TSCA submission search and decision tree process are included in Appendix A.3.4

A.3.4 Gray Literature Search Results for D4

Table Apx A-12 provides a list of gray literature sources that yielded results for D4.

Table Apx A-12. Gray Literature Sources that Yielded Results for D4

Source
Agency

Source Name

Source Type

Source
Category

Source Website

OECD

OECD: Emission

Scenario

Documents

International
Resources

Assessment or

Related

Document

http: //www .oecd .ora/document/4 6/
0.2340.en 2649 201185 2412462
1 1 1 1.00.html

OECD

OECD: General
Site

International
Resources

General
Search

https://www.oecd.ora/

Env
Canada

Priority Substances
List Assessment
Report; State of
Science Report,
Environment
Canada Assessment

International
Resources

Assessment or

Related

Document

https://www.canada.ca/en/environm
ent-climate-

chanae/service s/canadian-
environmental-protection-act-
reaistrv/substances-list/prioritv-
list.html

Env
Canada

Screening
Assessment for the
Challenge

International
Resources

Assessment or

Related

Document

https://www.canada.ca/en/health-

canada/services/chemical-

substances/challenae/list.html

Aus. Assm.

NICNAS

Assessments (Eco)

International
Resources

Assessment or

Related

Document

https ://www.nicnas. aov.au/chemica

1-information/imap-

assessments/imap-assessments

Aus. Assm.

NICNAS
Assessments
(Human Health.
Tier I. II or III)

International
Resources

Assessment or

Related

Document

https ://www.nicnas. aov.au/chemica

1-information/imap-

assessments/imap-assessments

CPSC

Technical Reports:

Exposure/Risk

Assessment

Other US

Agency

Resources

Technical
Report

https://www.cpsc.aov/Research~
Statistics/Chemicals

Page 90 of 124


-------
Source
Agency

Source Name

Source Type

Source
Category

Source Website

NLM

National Library of

Medicine's

HazMap

Other US

Agency

Resources

Database

https ://haz-map .com/

NLM

National Library of

Medicine's

PubChem

Other US

Agency

Resources

Database

https://pubchem.ncbi.nlm.nih.sov/

EPA

Office of Air: Air
Emission Factors
(AP-42)

US EPA
Resources

Regulatory
Document or
List

https://www.epa.20v/air-emissions-

factors-and-auantification/ap-42-

compilation-air-emissions-factors

EPA

EPA Office of
Water: Ambient
Water Quality
Criteria documents

US EPA
Resources

Assessment or

Related

Document

https://www.epa.eov/wac

EPA

EPA: Generic
Scenario

US EPA
Resources

Assessment or

Related

Document

https://www.epa.20v/tsca-
screen i n e-too 1 s/chc m stcc r-
chemical-screenine-tool-exposures-
and-environmental-
releases#eenericscenarios

ECHA

European Chemicals
Agency (ECHA)
Documents

International
Resources

Assessment or

Related

Document

https://echa.europa.eu/information-
on-chemicals

TERA

International
Toxicity Estimates
for Risk (ITER)

Other
Resources

Database

https://tera.ora/iter/

KOECT

Kirk-

Othmer Encyclopedi
a of Chemical
Technology Journal
Article

Other
Resources

Encyclopedia

https://onlinelibrarv.wilev.com/doi/
book/10.1002/0471238961

Page 91 of 124


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A.4 Summary of Literature Cited in the SEHSC Submission

As part of the SEHSC submission requesting the risk evaluation for D4 (Docket ID: EPA-HQ-OPPT-
2018-0443). data were submitted to EPA separately from the systematic review search process outlined
for peer-reviewed and gray literature data in Appendix A.2 and Appendix A.3, respectively. Data from
the SEHSC submission were compared to the search results from the systematic review process to
determine the overlap in the reference pools. The manufacturer submitted 391 total references with their
request. In the separate systematic review search process, EPA identified 1,750 total references, 232 of
which had already been provided by the manufacturer, and 1,518 of which were not included in the
SEHSC submission (as shown in FigureApx A-2). The remaining 159 sources provided by the
manufacturer that were not captured in the peer review and TSCA search submissions for D4 data will
undergo the appropriate systematic review steps (e.g., additional deduplication, full-text screening, data
evaluation and integration). Therefore, EPA may refine and revise the numbers in Figure Apx A-2
following further evaluation using systematic review methods.

Figure Apx A-2. Venn Diagram of Literature Identified by EPA vs. the SEHSC Submission

References identified by
both EPA and tbe

Page 92 of 124


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Appendix B PHYSICAL AND CHEMICAL PROPERTIES OF D4

Table Apx B-l summarizes statistics for the physical and chemical property values identified through
systematic review as of January 2021. The "N" column indicates the number of unique primary sources
of data for that endpoint. That is, if multiple sources presented equivalent values and cited the same
primary source, only one of those was included in these statistics and included in the statistical
calculations. All physical and chemical property values that were extracted and evaluated as of January
2021 are presented in the supplemental file Data Extraction and Data Evaluation Tables for Physical
and Chemical Property Studies (Docket ID: EP A-HQ-OPPT-2018-0443).

Table Apx B-l. Physical and Chemical Properties of D4

Property or Endpoint

N

Unit

Mean

Standard
Deviation

Min

Max

Molecular formula

-

-

NA

NA

NA

NA

Molecular weight

-

g/mol

NA

NA

NA

NA

Physical state

3

-

NA

NA

NA

NA

Physical properties

5

-

NA

NA

NA

NA

Melting point

20

C

17.6

1.5

170.0

18.5

Boiling point

16

C

175.2

1.5

170.0

176.4

Density

11

g/cm3

0.956

0.002

0.9497

0.9600

Vapor pressure

5

mm Hg

0.946

0.148

0.696

1.05

Vapor density

0

-

-

-

-

-

Water solubility

2

mg/L

0.065

0.013

0.056

0.074

Octanol/water partition coefficient (log
Kow)

2

-

6.95

0.04

6.92

6.98

Henry's Law constant

4

atmm3/mol

5.05

5.77

0.08

11.8

Flash point

6

C

55.7

1.0

54.0

57.0

Auto flammability

0

C

-

-

-

-

Viscosity

5

CP

2.375

0.207

2.187

2.700

Refractive index

8

-

1.3967

0.0022

1.394

1.401

Dielectric constant

1

-

-

-

-

-

Page 93 of 124


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Appendix C ENVIRONMENTAL FATE AND TRANSPORT
PROPERTIES OF D4

Table Apx C-l provides the environmental fate characteristics that EPA identified and considered in
developing the scope for D4. This table may be updated as EPA collects additional information through
systematic review methods and by reviewing information provided in the SEHSC submission requesting
the risk evaluation for D4 (Docket ID: EPA-HO-OP	>4431

Table Apx C-l. Environmental Fate and Transport Properties of D4

Property or Endpoint

Value(s)"

Reference(s)

Direct photodegradation

Not expected to be susceptible to direct
photolysis by sunlight because D4 does
not contain chromophores that absorb at
wavelengths >290 nm

NLM (2020)

Indirect

photodegradati on

ti/2 > 2,500 years (based O3 of 10~9
mol/L in urban locations)

3ke et al. (2009) based on

Abe et al * l'!M)



ti/2 = 11.4 days (based on *OH reaction
rate constant of 0.94x 10~12
cm3/mol-second at 24 C and a 12-hour
day with 1 x 106 OH/cm3)

\il mson! I,v!i



ti/2 = 8.5 days (based on *OH reaction
rate constant of 1.3 x 10~12
cm3/mol-second at 24 C and a 12-hour
day with 1.5xl06 OH/cm3)

Sommerlade et al. (1993)



ti/2 = 5.1 days (based on *OH reaction
rate constant of 2.1 x 10~12
cm3/mol-second at 40 C and a 12-hour
day with 1.5xl06 OH/cm3)

Safron et al. (2:

Indirect

photodegradati on

ti/2 = 4.7 days (based on *OH reaction
rate constant of 2.3 x 10~12
cm3/mol-second at 40 C and a 12-hour
day with 1.5xl06 OH/cm3)

\uo et al. (i )



ti/2 = 11.3 days (based on *OH reaction
rate constant of 0.95x 10~12
cm3/mol-second at 25 C and a 12-hour
day with 1.5xl06 OH/cm3)

Kim and Xu (2



ti/2 = 10.1 days (based on *OH reaction
rate constant of 1.1 x 10~12
cm3/mol- second at 21 C and a 12-hour
day with 1.5xl06 OH/cm3)

Bernard et al. (2018)



ti/2 = 2.2 days calculated from measured
atmospheric D4 concentrations
(excluding manufacture sites,

Xu et al. (2019b)

Page 94 of 124


-------
Property or Endpoint

Value(s)"

Reference(s)



wastewater treatment plants, and
landfills)



ti/2 = 8.3 days (based on *OH reaction
rate constant of 1.3 x 1CT12
cm3/mol-second at 24 C and a 12-hour
day with 1.5xl06 OH/cm3)

\lion am! < 'tcvvne (2020)

Hydrolysis (water)

ti/2 = 21 days at pH 7 and 10 C
into linear dimethylsiloxane-a,co-diol
oligomers (silanols) with (DMSD as
final product (OECD 111)

EC/HC (2008) based on

Durham (2005)

ti/2 = 16.7 days at pH 7 and 12 C;
ti/2 = 2.9 days at pH 8 and 9 C
into linear dimethylsiloxane-a,co-diol
oligomers (silanols) with DMSD as
final product (OECD 111)

3ke et al. (2009) based on
Durham (2005)

ti/2 = 15.2, 4.1, 1.6, and 0.4 days at 4,
20, 35, and 55 C (respectively) and pH
7 (OECD 111)

Gatidou et al. (

ti/2 = 15.6, 6.3, and 2.3 hours at pH 7.8,
8.5, and 9.2 (respectively) and 22 C
with DMSD as final product

Xu et al. (2016)

Hydrolysis (sediment)

ti/2 = 49 days 22 to 25 C into linear
siloxanes with DMSD as final product
(OECD 308)

EC/HC (2008) based on Xu and

Miller (2008)

ti/2 = 365 days in anaerobic sediment
and 242 days in aerobic sediment at 24
C (OECD 308)

ECHA (2015a) based on Xu
(2009) and Xu and Miller
(2009)

Abiotic degradation in
soil

ti/2 = 1-22 hours in Oxisol from Hawaii
ti/2 = 3.5-22 days in Alfisol from
Michigan

Rate depends on soil water content with
DMSD as final product

>9) and Xu and Chandra

ti/2 = 3.3, 3.4, 6.2, 7.9, and 11.6 hours in
soil with 20.7% clay and with crude oil
at 0.08, 0.4, 2, 10, and 40 mg/g
(respectively) at 25 C (capped vials)

Shi et al. (2

ti/2 = 5.6, 7.4, 8.8, 15.1, and 21.1 days
in soil with 20.7% clay and with crude
oil at 10, 20, 50, 100, and 200 mg/g
(respectively) at 25 C

Xu et al. (2019a)

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Property or Endpoint

Value(s)"

Reference(s)



ti/2 = 4.1-5.3 days in temperate soil at
relative humidity of 50-90%

SEHSC (2020) based on Xu

(2007)

Biodegradation
(aerobic)

Not likely to undergo biodegradation in
water based on limited biodegradation
(3.7%) in 28 days (OECD 310)

EC/HC (2008) based on
Gledhill (2005)

Biodegradation
(anaerobic)

Not likely to undergo anaerobic
biodegradation based on limited
biodegradation (3%) after 100 days
under anaerobic conditions with sewage
sludge

Grumping et al. (1999)

Wastewater treatment

89% mean total removal from four
wastewater treatment facilities

HvdroOual Inc (1993)

94.6% average total removal (57 to
60% by sludge and 33 to 38% by
volatilization) at three wastewater
treatment facilities

Mueller et j 5)

Wastewater treatment

86.4%) total removal at pilot plant
system

Parker et al. (1999)

5%> total removal (9% by sludge) at one
wastewater treatment facility

Kittson et al. (201 '<)

76-93%) average total removal (19 to
29.4%o by excess sludge) by traditional
process and 59% by reverse osmosis
from measurements at three wastewater
treatment facilities

Xu et al. (2013)

98%o mean total removal at 11
wastewater treatment facilities

Wane et al.

96% total removal (29% by sludge) at
one wastewater treatment facility

Wane et al. (2015)

100%o total removal by biological
aerated filter and (35% by sludge) and
85.7%o total removal by anaerobic-oxic
(65%o by sludge) at two wastewater
treatment facilities

Li et al. (2016)

76% total removal (27% by sludge) at
one wastewater treatment facility

Xu et al. (2016)

96%) mean total removal at nine
wastewater treatment facilities

Horii et al. (2019)

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Property or Endpoint

Value(s)"

Reference(s)



99% total removal (0% by
biodegradation, 60% by sludge, 39% by
volatilization to air; estimated)6

U.S. EPA. (2012b)



4.09 (BCFss = 12,400 L/kg) in fathead
minnows (Pimephales promelas) using
radio-labeled D4

F adder 5)



3.48 to 3.74 (BCFss = 3,000-4,000 and
BCFk = 4,100-5,500) in common carp
{Cyprinus carpio)

ECHA (2015b)

Log BCF

3.47 (BCFk = 2,953 L/kg wet weight)
calculated for rainbow trout
{Oncorhynchs mykiss) using a model
accounting for adsorption, distribution,
metabolism, and elimination

SEHSC (2020)



3.32 (BCF = 2,104 L/kg wet weight) in
common carp (Cyprinus carpio) based
on rates of update and clearance

Xue et al. (2020)



4.11 (BCF = 1.30xl04) (estimated)6

U.S. EPA (2012b)

Log BAF

4.11 (BCF = 1.30xl04) (estimated)6

U.S. EPA (2012b)



0.18-4.6 for rainbow trout
(iOncorhynchs mykiss)

Brooke et al. (2009)



2.4 for lake trout (
-------
Property or Endpoint

Value(s)"

Reference(s)



3.2 for Japanese snapping shrimp
(Alpheus /c//;o/7/67/.s)-plankton based on
stable isotope analysis

Xue et al. C



0.36 calculated for rainbow trout
(Oncorhynchs mykiss) using a model
accounting for adsorption, distribution,
metabolism, and elimination

SEHSC (2020)



13.3-20 for oligochaete (Lumbriculus
variegatus) from sediment spiked with
D4

(ECHA. 2012) based on

Wildlife International Ltd
(2008)



2.2,	1.3, and 0.7 for midge (Chironomus
tentans) larvae in sediment with 0.3,

2.3,	and 4.1 organic carbon content (%),
respectively

Wane et al. (2013a) based on
Kent et

Biota sediment

>1 for many species (especially for
some benthic invertebrate species) in a
freshwater lake

Wane et al. (2013a) based on
Powell et al. (2009)

accumulation factor
(BSAF)

0.445 to 1.61 in bottom fish
(Hexagrammos otakii) from the marine
sea near Dalian, China

Hone et al. (2014)



<6.2 in Arctic char (Salvelinus alpinus)
and from 0.5 to 3.3 in three-spined
sticklebacks (Gasterosteus aculeatus)
from Lake Storvannet, Norway

Kroeseth et al (2017)



0.42 in mollusks including mussel
(Mytilus galloprovincialis), venus clam
(Cyclina sinensis), and oyster
(Crassostrea talienwhanensis) from
Bohai Sea, China

Zhi et al. (2



0.24 to 0.36 freshwater aquatic food
chain in Lake Pepin, Minnesota

IA. (2012) based on Powell
et al. (2009)

Trophic magnification
factor (TMF) (kg
lipid/kg lipid, unless
noted)

D4 was below the level of quantitation
in most of samples from pelagic
freshwater food web of Lakes Mj0sa
and Randsfjorden, Norway

Borea et al (2013)

0.73 to 1.1 in food web of Lake Erie

McGoldrick et al. (2014)



1.16 in food web of the Dalian Bay,
Chinese Yellow Sea, China

Jia et al. (2015)

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Property or Endpoint

Value(s)"

Reference(s)



1.3 (least squares regression) and 0.6
(bootstrap) in food web of Tokyo Bay,
Japan

Powell et al. (2



0.5-0.7 in food web of Inner and Outer
Oslofjord, Norway

Powell et al. (2018)



1.7 in food web of Bohai Sea, China

Cui et al (2

No significant relationship with trophic
position in food web of Inner Oslofjord,
Norway

Norwegian Environment
V \ )

<1 in food web of Shuangtaizi estuary,
China

Xue et al. C

Soil organic carbon:
water partition
coefficient (log Koc)

4.22 (Koc = 1.66xl04)

Kozerski et al. (2014)

6.27 (Koc = 184.3><104) at 0 C
(Calculated)

5.99 (Koc = 98.4><104) at 5 C
(Calculated)

5.06 (Koc= 11.5xl04)at21 C
5.17 (Koc = 14.8xl04) at 25 C

Panagoooulos et al. (2

4.21 (Koc = 1.62xl04; MCI method);
4.35 (Koc = 2.26xl04; Kow method)
(estimated)13

U.S. EPA. (2012b)

Dissolved organic
carbon: water partition
coefficient (log Kdoc)

5.05 (Kdoc= 11.2xl04)

Panagoooulos et al. (2

Sludge: water
partitioning coefficient
(log Kd)

1.94 to 4.05 (Kd = 88 to 11350 L/kg) at
two wastewater treatment facilities

Xu et al. (2013)

3.38 (Kd = 2,399 L/kg) mean value at
one wastewater treatment facility

Hieisou et al. (201 '<)

3.30 (Kd = 1,995 L/kg) to primary
sludge and 3.64 (Kd = 4,365 L/kg) to
secondary sludge

Wang et al. (2015)



2.32 (Kd = 209 L/kg) to anaerobically
digested sludge at 35 C

Gatidou et;

a Measured unless otherwise noted.

b EPI Suite Physical Property Inputs: log Kow = 6.74; MP = 17.5 C; VP = 1.05 mm Hg; WS = 0.056 mg/L);
SMILES C[Si] l(C)0[Si](C)(C)0[Si](C)(C)0[Si](C)(C)01

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Appendix D REGULATORY HISTORY

The chemical substance, D4, is subject to federal and state laws and regulations in the United States (see
TableApx D-l and TableApx D-2). Regulatory actions by other governments, tribes, and international
agreements applicable to D4 are listed in Table Apx D-3.

D.l Federal Laws and Regulations

Table Apx D-l. Federal Laws and Regulations

Statutes/Regulations

Description of Authority/Regulation

Description of Regulation

I-PA statutes regulations

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.

D4 manufacturing (including
importing), processing, and use
information is reported under
the CDR rule C85 FR 20122.
April 9, 2020).

TSCA - section 8(b)

EPA must compile, keep current and
publish a list (the TSCA Inventory) of each
chemical substance manufactured (included
imported) or processed in the United States.

D4 (Cyclotetrasiloxane,
2,2,4,4,6,6,8,8-octamethyl-) was
on the initial TSCA Inventory
and therefore was not subject to
EPA's new chemicals review
process under TSCA section 5
( 09, March 29, 1995)

TSCA - section 8(d)

Provides EPA with authority to issue rules
requiring producers, importers, and (if
specified) processors of a chemical
substance or mixture to submit lists and/or
copies of ongoing and completed,
unpublished health and safety studies.

Two substantial risk reports
received for D4: one 1996
reproductive toxicity report, one
2017 environmental monitoring
report (U.S. EPA, ChemView;
accessed December 16, 2020)

TSCA - section 8(e)

Manufacturers (including importers),
processors, and distributors must
immediately notify EPA if they obtain
information that supports the conclusion
that a chemical substance or mixture
presents a substantial risk of injury to health
or the environment.

Thirty-nine risk reports received
for D4 (Received: 1992-2017.
U.S. EPA, ChemView;
(accessed December 16, 2020).

TSCA - section 4

Provides EPA with authority to issue rules,
enforceable consent agreements and orders
requiring manufacturers (including
importers) and processors to test chemical
substances and mixtures.

EPA required testing for the
presence of D4 in several
environmental media under an
enforceable consent agreement
with five manufacturers. The
testing was completed in 2017

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Statutes/Regulations

Description of Authority/Regulation

Description of Regulation





and the final test report can be
found in docket EPA-HO-
OPP .09.

Thirteen chemical data
submissions from test rules
received for D4: one acute
aquatic plant toxicity study, four
acute aquatic toxicity studies,
three chronic aquatic toxicity
studies, two bioaccumulation
potential studies and two water
solubility studies (U.S.
EPA, ChemView; accessed
December 16, 2020).

Oilier federal statutes regulations

Federal Food, Drug, and
Cosmetic Act (FFDCA)
- section 408

FFDCA governs the allowable residues of
pesticides in food. Section 408 of the
FFDCA provides EPA with the authority to
set tolerances (rules that establish
maximum allowable residue limits), or
exemptions from the requirement of a
tolerance, for pesticide residues (including
inert ingredients) on food. Prior to issuing a
tolerance or exemption from tolerance, EPA
must determine that the pesticide residues
permitted under the action are "safe."
section 408(b) of the FFDCA defines "safe"
to mean a reasonable certainty that no harm
will result from aggregate, nonoccupational
exposures to the pesticide. Pesticide
tolerances or exemptions from tolerance
that do not meet the FFDCA safety standard
are subject to revocation under FFDCA
section 408(d) or (e). In the absence of a
tolerance or an exemption from tolerance, a
food containing a pesticide residue is
considered adulterated and may not be
distributed in interstate commerce.

D4 (Cyclotetrasiloxane,
octamethyl-) is approved for
nonfood use. D4 (Methylated
silicones) is approved for food
use as an antifoaming agent
used pre- and post-harvest. CFR
1 \0  10, reassessed 6/1/2006
(accessed December 16, 2020).

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D.2 State Laws and Regulations

Table Apx D-2. State

^aws 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 D4, including Vermont (18 V.S.A  1776), Maine10 (38
MRSA Chapter 16-D), and Minnesota (Toxic Free Kids Act Minn. Stat.
116.9401 to 116.9407).

Two states have amended their reporting laws for chemicals in children's
products containing D4, including Oregon (no longer needs to be reported as
of January 1, 2019) (Oregon Toxic-Free Kids Act, Senate Bill 478, 2015)
and Washington State (CHCC removed by Rule Amendment in 2017)
(Wash. Admin. Code 173-334-130).

Other

California lists D4 as a designated prioritv chemical for biomonitoring under
criteria established by California SB 1379 (Biomonitoring California,
Priority Chemicals, February 2019).

The Oregon Department of Environmental Quality lists D4 as a priority
persistent pollutant (Oregon SB 737).

New York proposed Bill No A06892 to Amend the General Business Law,
in Relation to Requiring Cosmetic Packaging to Bear a Warning Label,
would require warning labels on cosmetics containing D4 (A. 6892, 232nd
Leg., Reg. Sess. (N.Y. 2009)).

D.3 International Laws and Regulations

TableApx D-3. Regulatory Actions by Other Governments, Tribes, and International
Agreements		

Country/
Organization

Requirements and Restrictions

Canada

D4 is on the Domestic Substances List. (Government of Canada.
Managing substances in the environment. Substances search; accessed
December 15, 2020).

D4 is on the is on the Canadian List of Toxic Substances (CEPA 1999
Schedule 1). Canada required pollution prevention plan implementation
for D4 in 2017 for industrial effluents to prevent or minimize D4 releases

10 Maine added D4 to its reporting laws for chemicals in children's products in July 2009 (38 MRSA Chapter 16-D). In
January 2017, Maine DEP received a petition to remove certain silicone substances from the Chemicals of Concern list. D4
was not included in that request.

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Country/
Organization

Requirements and Restrictions



to the environment from industrial users (Canada Gazette, Part I,
Saturday, January 15, 2011; Vol. 145, No. 3, Supplement).

The Government of Canada published a Draft Screening Assessment for
the Siloxanes Group on June 1, 2019.

European Union

D4 is registered for use in the EU (European Chemicals Agency [ECHA]
database; accessed December 15, 2020).

In 2018, D4 was added Annex XVII of regulation (EC) No 1907/2006 -
REACH (Registration, Evaluation, Authorization and Restriction of
Chemicals). The restriction stipulates that D4 shall not be placed on the
market in wash-off cosmetic products in a concentration equal to
or greater than 0.1% by weight after January 31, 2020. (ECHA database;
accessed December 16, 2020).11

In 2018, D4 was listed on the Candidate list as a Substance of Very High
Concern (SVHC) under regulation (EC) No 1907/2006 - REACH due to
meeting the criteria for identification as a PBT (Article 57d) and vPvB
substance (Article 57e). (ECHA database; accessed December 15, 2020).12

In 2019 an intent to register a restriction proposal was submitted. The
restriction would stipulate that leave-on personal care products and other
consumer/professional products containing D4 in concentrations > 0.1%
shall not be placed on the market. (ECHA database; accessed December
15, 2020).

Australia

D4 was assessed under Environmental Tier II of the Inventory Multi-
Tiered Assessment and Prioritisation (IMAP). (National Industrial
Chemicals Notification and Assessment Scheme [NICNAS], Chemical
inventory; database accessed December 15, 2020).

Japan

D4 is regulated in Japan under the Act on the Evaluation of Chemical
Substances and Regulation of Their Manufacture, etc. (Chemical
Substances Control Law; [CSCL]) (National Institute of Technology and
Evaluation [NITE] Chemical Risk Information Platform [CHIRP];
accessed December 15, 2020).

United Kingdom

D4 was assessed based on the methods outlined in the European Union
(EU) Technical Guidance Document (TGD) for the Risk Assessment of
New and Existing Chemicals (Environmental Risk Assessment Report for
Octamethylcyclotetrasiloxane; UK Environment Agency. April 2019)

11	In April 2018, industry filed a legal action in the Court of Justice of the European Union

(General Court) seeking, among other things, annulment of the Wash-Off Restriction. See https://eurlex.europa.eu/legal-
content/EN/TXT/?qid=1570630612867&uri=CELEX:62018TN0226.

12	In September 2018, industry filed a legal action in the Court of Justice of the European Union
(General Court) seeking annulment of the ECHA decision to list D4 as a SVHC. See https://eurlex.
europa. eu/legal-content/EN/TXT/?qid= 1518304338301 &uri=CELEX:62018TN0519.

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Appendix E PROCESS, RELEASE, AND OCCUPATIONAL
EXPOSURE INFORMATION

This appendix provides information and data found in preliminary data gathering for D4.

E.l Process Information

Process-related information potentially relevant to the risk evaluation may include process diagrams,
descriptions, and equipment. Such information may inform potential release sources and worker
exposure activities.

E.l.l Manufacture (Including Import)

In the 2016 CDR, nine facilities reported manufacturing or importing D4 for calendar year 2015.
According to the 2016 public CDR data, D4 is manufactured as a liquid, and may be imported as either a
liquid or a dry powder (	20a).

E.J.LI Domestic Manufacturing

The manufacture of siloxane compounds involves a series of reactions. First, the starting material, quartz
(silica), is mixed with coke and reduced to silicon metal by heating in an electric arc furnace. The silicon
metal then reacts with methyl chloride vapor to produce chlorosilanes. Subsequent hydrolysis of
chlorosilanes and condensation of silanol intermediate then produce a mixture of linear and cyclic
siloxanes, which can be further processed, split, or distilled into specific siloxane compounds such as D4
(EP A-HO-OPPT-2018-0443 -00041

E.l.1.2 Import

Commodity chemicals such as D4 may be imported into the United States in bulk via water, air, land,
and intermodal shipments (Tomer and Kane. 2015). These shipments take the form of oceangoing
chemical tankers, railcars, tank trucks, and intermodal tank containers. Chemicals shipped in bulk
containers may be repackaged into smaller containers for resale, such as drums or bottles. Domestically
manufactured commodity chemicals may be shipped within the United States in liquid cargo barges,
railcars, tank trucks, tank containers, intermediate bulk containers (IBCs)/totes, and drums. Both
imported and domestically manufactured commodity chemicals may be repackaged by wholesalers for
resale; for example, repackaging bulk packaging into drums or bottles. The type and size of container
will vary depending on customer requirements. In some cases, quality control samples may be taken at
import and repackaging sites for analyses. Some import facilities may only serve as storage and
distribution locations, and repackaging/sampling may not occur at all import facilities.

According to the 2016 CDR, D4 may be imported as a neat liquid (greater than 90 percent concentration
by weight) or as part of a liquid or dry powder formulation containing 1 to 30 percent D4 by weight.

(U.S. EPA. 2020a).

E.1.2 Processing and Distribution

E. 1.2.1 Reactant or Intermediate

Processing as a reactant or intermediate is the use of D4 as a feedstock in the production of another
chemical via a chemical reaction in which D4 is consumed to form the product. A major use of D4 is as
a monomer for silicone polymers. In this process, D4 undergoes equilibration polymerization to make
polydimethylsiloxane (PDMS) and a wide range of functionalized siloxanes bearing.

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D4 is also an intermediate to produce decamethyltetrasiloxane. In this process, D4 and
hexamethyldisiloxane are fed to a reactor and allowed to reach equilibrium. The equilibrate is removed
from the reactor and distilled to separate the desired product from the unreacted hexamethyldisiloxane
and D4, which are returned to the reactor (EPA-HQ-OP	>443-0004).

E.1.2J! Incorporated into a Formulation, Mixture, or Reaction Product

Incorporation into a formulation, mixture, or reaction product refers to the process of mixing or blending
of several raw materials to obtain a single product or preparation. Exact process operations involved in
the incorporation of D4 into a chemical formulation, mixture, or reaction product are dependent on the
specific manufacturing process or processes involved. According to the 2016 CDR and the SEHSC
submission (EPA-HQ-QPPT-2018-0443-0004). D4 is used as an intermediate in synthetic rubber
manufacturing, cyclic crude and intermediate manufacturing, and all other basic inorganic chemical
manufacturing. D4 and polymer containing residual D4 monomer can also be processed and
incorporated into various end products in many industrial sectors, including computer and electronic
product manufacturing, asphalt paving, roofing, and coating materials manufacturing, electrical
equipment, appliance, and component manufacturing, as a component of a processing aide (e.g.
antifoaming agent), rubber product manufacturing, all other chemical product and preparation
manufacturing, as well as miscellaneous manufacturing, (U.S. EPA. 2020a) and (EPA-HQ-OPPT-2018-
0443-0004). and (EPA-HQ-QPPT-2018-0443-0027).

E.I.2.3 Repackaging

Repackaging refers to preparation of a chemical substance for distribution into commerce in a different
form, state, or quantity than originally received/stored, where such activities include transferring a
chemical substance from a bulk storage container into smaller containers.

E.1.3 Uses

E. 1.3.1 Aircraft Maintenance

D4 is used in general aircraft maintenance (EPA-HQ-O	) EPA has received

information that D4 may be used for aircraft maintenance. It is unclear exactly how D4 is used for this
purpose, including the points of possible exposure(s) and/or release(s).

E.1.3.2 Adhesives and Sealants

D4 may be present in a number of adhesive and silicone sealants at concentrations ranging from less
than 1 percent to up to 10 percent. Adhesive application method depends on a variety of factors
including the type of adhesive, type of substrate, size and geometry of the substrate, and the precision
requirement of the bond. The common application methods are spray, roll, curtain, and syringe or bead
application. During application, volatile components are expected to evaporate, resulting in emissions to
air. The application process may also generate process wastes, such as overspray, depending on the
method used (OECD. 2015).

E. 1.3.3 Automotive Care Products

D4 is present at less than 0.5 percent concentration in a leather and vinyl protector product. The product
is used to preserve the appearance of leather and vinyl in cars, trucks and vans, and is available in an
aerosol can (3M. 2019).

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E.1,3.4 Furnishing, Cleaning, Treatment/Care Products

D4 is present as a residual (<1 percent) in several laundry products, including laundry detergent and
fabric softeners (Ecolab. 2019. 2017; Alpine Specialty Chemicals Ltd. 2016a. b). The use of laundry
products typically results in down-the-drain releases to wastewater.

E. 1.3.5 Ink, Toner, and Colorant Products

D4 is a component in several screen printing inks at concentrations up to 2 percent (3M. 2018).

EX3.6 Laboratory Chemicals

D4 is used neat (90 percent concentration or higher) in laboratory settings, including as a gas
chromatography (GC) reference standard, as a probe liquid for nuclear magnetic resonance
cryoporometry (NMRC), and in the synthesis of other polymers such as PDMS (Sigma Aldrich. 2020;
TCI America. 2019; Sigma Aldrich. 2018).

E. 1.3.7 Paints and Coatings

D4 may be a component of paints and coatings, including automotive coating (B&B Blending LLC.
2019). wood floor finish (Buckeye International. 2018). and oil-based paint (Rust-Oleum Corporation.
2018). The concentration of D4 varies by product but was found to be as high as 55 percent in a type of
automotive ceramic coating. This specific coating protects automobile from weather, chemicals,
physical abrasion, and UV rays, and provides water and dirt repellency (	ending LLC. 2019).

The application method varies by product. For example, ceramic automotive coating can be applied by
saturating a suede applicator with drops of coating material from a dripper bottle, and then applying to
the vehicle using a cross-hatch pattern. The coating is then allowed to cure at ambient temperature
(B&B Blending LLC. ^ ). Floor finishes may be applied using a T-bar applicator (Buckeye
International. 2018). Interior and exterior paints can be applied by roller, brush, or high-pressure airless
spray gun (Rust-Oleum Corporation, 2018). In general, spray coating is the most common method to
apply a liquid formulation to a surface (OECD. 2009b).

D4 may also be present as a residual (<1 percent) in various silicone-based coatings. The most
prominent silicone coatings are pressure-sensitive adhesives, plastic hardcoats, and paper release
coatings (Kirk-Othmer. 2008).

E. 1.3.8 Plastic and Rubber Products

D4 is present as a residual in silicone polymer, which is then used to make a wide range of plastic and
rubber products that may have industrial, commercial, or consumer applications.

Silicone rubber is made by vulcanizing high molecular weight linear PDMS polymer (often called gum),
which contains residual D4 monomer. The specific ratio of polymer, fillers, and cure catalysts can be
customized to each application to provide the desired properties. Silicone rubber is most commonly
fabricated by compression molding catalyzed gum stock at 100-180 C under 5.5-10.3 MPa. The
materials are then extruded to form tubes, rods, wires, cable insulations, and articles with continuous
profiles. Silicone rubber can also be processed through liquid injection molding (Rich et at.. 2000).

E.1.4 Disposal

Each of the conditions of use of D4 may generate waste streams of the chemical that are collected and
transported to third-party sites for disposal, treatment, or recycling. Industrial sites that treat or dispose
on-site wastes that they themselves generate are assessed in each condition of use assessment. Similarly,
point source discharges of D4 to surface water are assessed in each condition of use assessment (point

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source discharges are exempt as solid wastes under the Resource Conservation and Recovery Act
[RCRA]). Wastes of D4 that are generated during a condition of use and sent to a third-party site for
treatment, disposal, or recycling may include the following:

	Pursuant to section 304(a) of the Clean Water Act (CWA), EPA recommends water quality
criteria pertaining to chemical pollutants in surface water to protect aquatic life or human health
considering the designated uses of the surface water. Priority pollutants comprise a subset of
these chemical substances, and the numbers of these priority pollutants are 103 and 25 in relation
to the protection of human health and aquatic life, respectively. States are required to adopt
numeric criteria pertaining to priority pollutants according to the CWA if the discharge or
presence of a priority pollutant could reasonably be expected to interfere with designated uses of
the affected waters adopted by a state. Once these numeric criteria are adopted by a state and are
approved by EPA, they become a part of the state's regulatory water quality standards.

According to the CWA, National Pollutant Discharge Elimination System (NPDES) discharge
permits must include effluent limits as stringent as necessary to meet a state's regulatory water
quality standards. Furthermore, these effluent limits must also be as stringent as necessary to
satisfy the technology-based effluent guidelines for the applicable source category (e.g., D4
manufacturing is covered under the Organic Chemicals, Plastics, and Synthetic Fibers [OCPSF]
point source category with effluent guidelines provided at 40 CFR part 414).

	D4 is not a regulated toxic pollutant (listed at 40 CFR 401.15) or priority pollutant (listed at 40
CFR part 423 Appendix A). However, state permit writers may consider issuing permit limits for
chemicals not listed as toxic or priority pollutants; these chemicals are referred to as
"nonconventional pollutants" in section 301(g) of the CWA. Discharge Monitoring Report
(DMR) data are submitted by NPDES permit holders to the permitting authority (i.e., the state or
directly to EPA) in accordance with the monitoring requirements of the facility's permit. NPDES
permit effluent limits are associated with approved monitoring analytical methods. Section
304(h) of the CWA directs EPA to promulgate these analytical methods, which are a requirement
for making NPDES permit effluent limits enforceable, and these methods are published at 40
CFR part 136. Analytical method(s) pertaining to D4 have not been promulgated. Consequently,
D4 has not been reported in the DMR data set for the past 15 years.

	Solid Wastes: Solid wastes are defined under RCRA as any material that is discarded by being
abandoned; inherently waste-like; a discarded military munition; or recycled in certain ways
(certain instances of the generation and legitimate reclamation of secondary materials are
exempted as solid wastes under RCRA). Solid wastes may subsequently meet RCRA's definition
of hazardous waste by either being listed as a waste at 40 CFR 261.30 to 261.35 or by meeting
waste-like characteristics as defined at 40 CFR 261.20 to 261.24. Solid wastes that are hazardous
wastes are regulated under the more stringent requirements of Subtitle C of RCRA, whereas non-
hazardous solid wastes are regulated under the less stringent requirements of Subtitle D of
RCRA. Solid wastes containing D4 may be regulated as a hazardous waste under RCRA waste
code D001 for ignitable liquids (40 CFR 261.21). D4 may also be comingled with solvent
mixtures that are RCRA hazardous wastes. These wastes would be either incinerated in a
hazardous waste incinerator or disposed to a hazardous waste landfill. Alternatively, D4 may be
comingled with waste that is not RCRA hazardous waste, and the resulting flash point of the
mixture may no longer meet the ignitability criterion for RCRA waste code D001. D4 in
consumer products may be disposed to municipal waste.

Page 107 of 124


-------
 Wastes Exempted as Solid Wastes under RCRA: Certain conditions of use of D4 may generate
wastes of D4 that are exempted as solid wastes under 40 CFR 261.4(a).

E.2 Preliminary Occupational Exposure Data

NIOSH Health Hazard Evaluations (HHEs) have not been conducted with a focus on D4 monitoring
and/or workplace exposure to date. D4 does not have an OSHA Integrated Management Information
System (IMIS) code. As such, OSHA has not collected monitoring data for this chemical.

Page 108 of 124


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Appendix F SUPPORTING INFORMATION - CONCEPTUAL MODEL FOR INDUSTRIAL
AND COMMERCIAL ACTIVITIES AND USES

Table Apx F-l. Worker ant

ONU Exposure Conceptual Model Supporting Tab

e

Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale

Manufacturing

Manufacturing
Import

Manufacturing
Import

Manufacture of
D4

Repackaging of
import containers

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids during manufacturing and
import activities.

Solid

Dermal

Worker

Yes

According to the 2016 CDR, D4 may
be imported in dry powder form.
Dermal contact with solids may occur
when D4 is imported as dry powder.

Liquid

solid

annuel

Dermal

ONU

\o

Dermal exposure is e\peeled In he
piiniai'iK lo worker u ho direelh
handle lhe chemical

Vapor

Inhalation

Worker

Yes

D4 is a semi-volatile liquid. Inhalation
exposure to vapor should be further
evaluated.

Vapor

Inhalation

ONU

Yes

Dust

Inhalation

Worker
ONU

Yes

According to the 2016 CDR, D4 may
be imported in dry powder form.
Inhalation to dust may occur during
solids transferring activities.

Solid

(settled

dust)

Dermal

Worker
ONU

Yes

Dust may settle on surfaces that
workers or ONUs may touch.

Processing

Processing as a
reactant

Adhesives and

sealant

chemicals

All other basic
inorganic
chemical mfg.

All other basic
organic
chemical mfg.

All other

Processing of D4
as a reactant,
precursor, or
monomer (incl.
processing of D4
to produce
silicone
polymers)

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids during activities such as
container unloading, equipment
maintenance and cleaning.

Solid

Dermal

Worker

Yes

D4 may be present in a solid powder
formulation. Dermal contact with
solids may occur during unloading
and transferring activities.

Liquid

solid

annuel

Dermal

ONU

\o

Dermal exposure is e\peeled lo he
piiniai'iK lii workeiN u ho direclK
handle I he chemical

Vapor

Inhalation

Worker

\ es>



Page 109 of 124


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Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale





chemical
product and
preparation



Vapor

Inhalation

ONU

Yes

D4 is a semi-volatile liquid. Inhalation
exposure to vapor should be further
evaluated.





mfg.



Dust

Inhalation

Worker

Yes

D4 may be present in a solid powder
formulation. Inhalation to dust may
occur during solids transferring
activities.





Synthetic
rubber mfg.



Dust

Inhalation

ONU

Yes





Plastic
material and
resin mfg.



Solid

(settled

dust)

Dermal

Worker
ONU

Yes

Dust may settle on surfaces that
workers or ONUs may touch.





All other basic
inorganic
chem mfg.



Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids during processing and use
of silicone polymer products
containing D4.





All other chem
product and
preparation
mfg.



Liquid
conlncl

Dermal

<>\l

\o

Domini exposure is especial In he
priiikii'il\ lo worker u Ik dneclK
handle I lie chemical







Vapor

Inhalation

Worker

Yes





Incorporation
into

Asphalt
paving,
roofing, and
coating
materials mfg.

Cyclic crude
and

intermediate
mfg.

Misc. mfg.

paint and
coating mfg.

Antifoaming
agent

Processing of
silicone polymer











Processing

formulation,
mixture, or
reaction
product

containing D4 to
produce other
chemicals and
products

Vapor

Inhalation

ONU

Yes

D4 is semi-volatile liquid and may
continue to evaporate after
incorporated into polymers and other
products. Inhalation exposure to vapor
should be further evaluated.

Page 110 of 124


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Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale



















Processing

Incorporation
into

formulation,
mixture, or
reaction
product

Computer and
electronic
product mfg.

Electrical
equipment,
appliance, and
component
mfg.

Processing of
silicone polymer
containing D4 to
produce
electronics
encapsulant or
coating

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids during processing and use
of silicone polymer products
containing D4.

Liquid
coulacl

Dermal

<>\l

\o

Dermal exposure is e\pecled In he
piiuiai'iK lo woikeis u ho direclls
handle llie chemical

Vapor

Inhalation

Worker

Yes

D4 is semi-volatile liquid and may
continue to evaporate after
incorporated into polymers and other
products. Inhalation exposure to vapor
should be further evaluated.

Vapor

Inhalation

ONU

Yes

Processing

Incorporation
into

formulation,
mixture, or
reaction
product

Rubber
product mfg.

Synthetic
rubber mfg.

Processing of
silicone polymer
containing D4 to
produce silicone
rubber
compounds

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids during processing and use
of silicone polymer products
containing D4.

Liquid
coulacl

Dermal

<>\l

\o

Dermal exposure is e\pecled lo he
piiuiai'iK lo workeiN u ho direclls
handle llie chemical

Vapor

Inhalation

Worker

Yes

D4 is semi-volatile liquid and may
continue to evaporate after
incorporated into polymers and other
products. Inhalation exposure to vapor
should be further evaluated.

Vapor

Inhalation

ONU

Yes

Page 111 of 124


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Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale





All other basic
inorganic
chem mfg.



Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids during packaging,
equipment maintenance and cleaning
activities.

Processing

Processing -
repackaging

All other chem
product and

Repackaging to
large and small
containers

Liquid
coulaci

Dermal

<>\l

\o

Dermal exposure is c\pecled In he
piiniariK lo woikeis u ho direclK
handle llie chemical





prep mfg.



Vapor

Inhalation

Worker

Yes

D4 is a semi-volatile liquid. Inhalation
exposure to vapor should be further
evaluated.





Misc mfg.



Vapor

Inhalation

ONU

Yes

Distribution

Distribution in
commerce

Distribution in
commerce

Distribution of
bulk shipments
of D4 and
formulated
products

Liquid/
solid
contact
Vapor

Dermal
Inhalation

Worker
ONU

Yes

EPA plans to analyze activities
resulting in exposures associated with
distribution in commerce (e.g.,
loading, unloading) throughout the
various life cycle stages and
conditions of use (e.g., manufacturing,
processing, industrial use, commercial
use, disposal) rather than a single
distribution scenario.









Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids when using products
containing D4.









Liquid
coulaci

Dermal

<>\l

\o

Dermal exposure is e\peeled In he
priuiai'iK lo workeiN u ho direelK
handle lhe chemical

Industrial Use

Other uses

Aircraft
maintenance

Use of D4 to
maintain aircraft

Vapor

Inhalation

Worker

Yes

Inhalation exposure from
volatilization of D4 during this
process should be further evaluated





Vapor

Inhalation

ONU

Yes

Inhalation exposure from
volatilization of D4 during this
process should be further evaluated









Mist

Inhalation

Worker

Yes

Workers may be exposed to mist if
products are spray-applied









Liquid

(settled

mist)

Dermal

Worker
ONU

Yes

Dermal exposure to liquid films
resulting from the settling of mist
should be further evaluated.

Commercial
uses

Adhesives and
sealants

Adhesives and
sealants

Use of adhesives
and sealants

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids when using silicone
polymer products containing D4.

Page 112 of 124


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Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale



Automotive
care products

Automotive
care products

Use of

automotive care
products (e.g.,
leather and vinyl
protector)

Liquid
annuel

Dermal

<>\l

\o

Dermal exposure is expected lo he
primariK lo workers who direelK
handle I lie chemical

Vapor

liihalalion

Worker

Yes,

liihalalion exposure from
volatilization of D4 residue in silicone
polymer should be further evaluated.

Vapor

Inhalation

ONU

Yes

Mist

Inhalation

Worker

Yes

Workers may be exposed to mist if
products are spray-applied

Liquid

(settled

mist)

Dermal

Worker
ONU

Yes

Dermal exposure to liquid films
resulting from the settling of mist
should be further evaluated.

Furnishing,
cleaning,
treatment/
care products

Fabric, textile,
and leather
products not
covered
elsewhere

Cleaning and
furnishing care
products

Use of cleaning
and laundry
products (e.g.,
detergent, fabric
softener)

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids when using silicone
polymer products containing D4.

Liquid
coulacl

Dermal

<>\l

\o

Dermal exposure is expected lo he
primarily lo workers w ho direelK
handle lhe chemical

Vapor

Inhalation

Worker

Yes

Inhalation exposure from
volatilization of D4 residue in silicone
polymer should be further evaluated.

Vapor

Inhalation

ONU

Yes

Page 113 of 124


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Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale

Commercial
uses

Ink, toner, and

colorant

products

Ink, toner, and

colorant

products

Screen printing

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal exposure
when transferring ink to printers or
during the printing process.

Liquid
eoulael

Dermal

<>\l

\o

Dermal exposure is expected In he
priniariK lo workers w ho direelK
handle llie chemical

Vapor

Inhalation

Wo ik or

Yes

liihalalion exposure from
volatilization of D4 residue in silicone
polymer should be further evaluated.

Vapor

Inhalation

ONU

Yes

Mist

Inhalation

Worker

Yes

Mist exposure is expected from high-
speed web-fed presses.

Liquid

(settled

mist)

Dermal

Worker
ONU

Yes

Dermal exposure to liquid films
resulting from the settling of mist
should be further evaluated.

Laboratory
chemicals

Laboratory
chemicals''

Use of D4 in
laboratories (e.g.,
reference
standard)

Liquid
Contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids when using D4 in
laboratories.

Liquid
eoulael

Dermal

<>\l

\o

Dermal exposure is expected In he
priniariK lo workers w ho direelK
handle lhe chemical

Vapor

Inhalation

Worker

Yes

D4 is semi-volatile liquid. Inhalation
exposure to vapor should be further
evaluated.

Vapor

Inhalation

ONU

Yes

Commercial
uses

Paints and
coatings

Paints and
coatings

Application of
paints and
coatings

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids when using silicone
polymer products containing D4

Liquid
eoulael

Dermal

<>\l

\o

Dermal exposure is expected lo he
primarily lo workers w ho direelK
handle lhe chemical

Vapor

Inhalation

Worker

Yes

Inhalation exposure from
volatilization of D4 residue in silicone
polymer should be further evaluated.

Vapor

Inhalation

ONU

Yes

Mist

Inhalation

Worker

Yes

Workers may be exposed to mist if
paints and coatings are spray-applied

Liquid

(settled

mist)

Dermal

Worker
ONU

Yes

Dermal exposure to liquid films
resulting from the settling of mist
should be further evaluated.

Plastic and
rubber
products not

Plastic and
rubber
products not

Use of plastic
and rubber
products

Solid

(migration

Dermal

Worker

Yes

Workers may have dermal contact
with silicone-based products and
articles, and dermal exposure resulting

Page 114 of 124


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Life Cycle
Stage

Category

Subcategory

Release/
Exposure
Scenario

Exposure
Pathway

Exposure
Route

Receptor/
Population

Plans to
Evaluate

Rationale



covered
elsewhere

covered
elsewhere



of D4 from
an article)







from migration of D4 from an article
should be further evaluated.

Solid

Dermal

<>\l

\n

Dermal exposure is c\pecled In he
piiuiaiiK In workeis u ho direclK
handle llie chemical

Vapor

Inhalation

Worker

Yes

Inhalation exposure from
volatilization of D4 residue in silicone
polymer should be further evaluated.

Vapor

Inhalation

ONU

Yes

Disposal

Disposal

Waste
handling,
treatment, and
disposal

Exposure
occuring during
disposal

Liquid
contact

Dermal

Worker

Yes

Workers may have dermal contact
with liquids when handling wastes
containing D4.

Liquid
coulacl

Dermal

<>\l

\n

Dermal e\pnsuic is e\peeled In he
primarily in wnikeis u hn diieclK
handle lhe chemical

Vapor

Inhalation

Worker

Yes

D4 is semi-volatile liquid. Inhalation
exposure to vapor should be further
evaluated.

Vapor

Inhalation

ONU

Yes

Dust

Inhalation

Worker
ONU

Yes

D4 vapor that is generated my adsorb
on dust particles in a landfill or else
dust containing D4 may be generated
during landfilling operations.

Page 115 of 124


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Appendix G SUPPORTING INFORMATION - CONCEPTUAL MODEL FOR CONSUMER
ACTIVITIES AND USES

Table Apx G-l. Consumer Exposure Conceptual Model Supporting Table

Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale

Consumer
use

Furnishing,
cleaning,
treatment/care
products

Fabric, textile,
and leather
products not
covered
elsewhere
(article)

Direct contact
through handling of
articles containing
chemical

Direct
contact

Dermal

Consumers

Yes

Dermal exposure may occur
for this condition of use

Direct contact
through mouthing of
articles containing
chemical

Mouthing

Oral

Consumers

Yes

Oral exposure may occur for
this condition of use

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Consumer
use

Packaging, paper,
plastic, hobby
products

Plastic and
rubber products
not covered
elsewhere
(article)

Direct contact
through handling of
articles containing
chemical

Direct
contact

Dermal

Consumers

Yes

Dermal exposure may occur
for this condition of use.

Direct contact
through mouthing of
articles containing
chemical

Mouthing

Oral

Consumers

Yes

Oral exposure may occur for
this condition of use.

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Page 116 of 124


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Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale







Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Consumer
use

Packaging, paper,
plastic, hobby
products

Toys,

playground, and
sporting
equipment
(article)

Direct contact
through handling of
articles containing
chemical

Direct
contact

Dermal

Consumers

Yes

Dermal exposure may occur
for this condition of use.

Direct contact
through mouthing of
articles containing
chemical

Mouthing

Oral

Consumers

Yes

Oral exposure may occur for
this condition of use.

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Consumer
use

Adhesives and
sealants

Adhesives and

sealants

(product)

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal,

Inhalation,

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Direct contact
through application
or use of products

Liquid
Contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumer who are directly
involved in using the
chemical.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Direct contact
through application
or use of products

Mist

Inhalation,
Dermal, Oral

Consumers
Bystanders

Yes

If product is applied as a mist,
inhalation, dermal, and oral
exposure would be expected.

Page 117 of 124


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Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale

Consumer
use

Automotive care
products

Automotive care

products

(product)

Long-term
emission/mass-
transfer, Abrasion,
Transfer to Dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Direct contact
through application
or use of products

Liquid
contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumer who are directly
involved in using the
chemical.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Direct contact
through application
or use of products

Mist

Inhalation,
Dermal, Oral

Consumers
Bystanders

Yes

If product is applied as a mist,
inhalation, dermal, and oral
exposure would be expected.

Consumer
use

Furnishing,
cleaning,
treatment/care
products

Cleaning and
furnishing care
products
(product)

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal,

Inhalation,

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Direct contact
through application
or use of products

Liquid
contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumer who are directly
involved in using the
chemical.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Direct contact
through application
or use of products

Mist

Inhalation,
Dermal, Oral

Consumers
Bystanders

Yes

If product is applied as a mist,
inhalation, dermal, and oral
exposure would be expected.

Page 118 of 124


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Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale







Direct contact
through handling of
products containing
chemical

Direct
contact

Dermal

Consumers

Yes

Dermal exposure may occur
for this condition of use.

Consumer
use

Furnishing,

Fabric, textile,
and leather

Direct contact
through mouthing of
products containing
chemical

Mouthing

Oral

Consumers

Yes

Oral exposure may occur for
this condition of use.

cleaning,

treatment/care

products

products not
covered
elsewhere
(product)

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.







Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.







Direct contact
through application
or use of products

Mist

Inhalation

Dermal

Oral

Consumers
Bystanders

Yes

If product is applied as a mist,
inhalation, dermal, and oral
exposure would be expected.

Consumer
use

Furnishing,
cleaning,
treatment/care
products

Laundry and
dishwashing
products
(product)

Direct contact
through application
or use of products

Liquid
Contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumer who are directly
involved in using the
chemical.



Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Consumer
use

Other

Animal

grooming

products

Direct contact
through application
or use of products

Liquid
Contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumer who are directly
involved in using the
chemical.

Page 119 of 124


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Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale







Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Direct contact
through application
or use of products

Mist

Inhalation

Dermal

Oral

Consumers
Bystanders

Yes

If product is applied as a mist,
inhalation, dermal, and oral
exposure would be expected.

Consumer
use

Paints and
coatings

Paints and

coatings

(product)

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Direct contact
through application
or use of products

Liquid
Contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumer who are directly
involved in using the
chemical.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Direct contact
through application
or use of products

Mist

Inhalation

Dermal

Oral

Consumers
Bystanders

Yes

If product is applied as a mist,
inhalation, dermal, and oral
exposure would be expected.

Consumer
use

Packaging, paper,
plastic, hobby
products

Plastic and
rubber products
not covered
elsewhere
(product)

Direct contact
through handling of
products containing
chemical

Direct
Contact

Dermal

Consumers

Yes

Dermal exposure may occur
for this condition of use.

Direct contact
through mouthing of
products containing
chemical

Mouthing

Oral

Consumers

Yes

Oral exposure may occur for
this condition of use.

Page 120 of 124


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Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale







Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Consumer
use

Packaging, paper,
plastic, hobby
products

Toys,

playground, and
sporting
equipment
(product)

Direct contact
through handling of
products containing
chemical

Direct
contact

Dermal

Consumers

Yes

Dermal exposure may occur
for this condition of use.

Direct contact
through mouthing of
products containing
chemical

Mouthing

Oral

Consumers

Yes

Oral exposure may occur for
this condition of use.

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dermal, oral, and inhalation
exposure from this condition
of use may occur.

Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Consumer
handling of
disposal and
waste

Wastewater,
liquid wastes,
and solid wastes

Wastewater,
liquid wastes,
and solid wastes

Long-term
emission/mass-
transfer, abrasion,
transfer to dust

Dust

Dermal

Inhalation

Oral

Consumers
Bystanders

Yes

Dust generation is possible
during the handling of solid
waste.

Direct contact
through handling or
disposal of products

Liquid
Contact

Dermal

Consumers

Yes

Exposure is expected to be
primarily restricted to
consumers who are directly
involved in handling and
disposal of the chemical.

Page 121 of 124


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Life Cycle
Stage

Category

Subcategory

Release from
Sou rcc

Exposure
Pathway

Route

Receptor/
Population

Plans to
Evaluate

Rationale







Long-term
emission/mass-
transfer through
application or use of
products

Vapor

Inhalation
Oral

Consumers
Bystanders

Yes

Inhalation and incidental
ingestion are possible.

Direct contact
thioimh application
or use of products

\llsl

Inhalation.
1 )crnial. oral

( onsiinici's
P>\slanders

No

Misi uciicnitioii is noi
expected diiinm ilie haiidlnm
or disposal

Page 122 of 124


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Appendix H SUPPORTING INFORMATION - CONCEPTUAL MODEL FOR
ENVIRONMENTAL RELEASES AND WASTES

Table Apx

1-1. General Population and

Environmental

Exposure Conceptual Model Supporting

Table



Life Cycle
Stage

Category

Release

Exposure
Pathway/Media

Exposure Route(s)

Receptor/
Population

Plans to
Evaluate

Rationale







Near facility
ambient air
concentrations

Inhalation

General population

Yes

D4 deposition to
nearby bodies of
water and soil are



Emissions to
air

Emissions to
air

Indirect
deposition to
nearby bodies of
water and soil
catchments

Oral
Dermal

General population

Yes

expected exposure
pathways, not
covered under other
EPA regulations,
and, therefore in
scope.







TBD

Aquatic and
terrestrial receptors

Yes

All





Direct release into
surface water and

TBD

Aquatic and
terrestrial receptors

Yes

Release of D4 into
surface water and
indirect partitioning
to sediment exposure
pathways to aquatic
and terrestrial
receptors will be
analyzed.

Wastewater or
liquid wastes

Industrial pre-
treatment and
wastewater
treatment, or
POTW

indirect
partitioning to
sediment

Oral
Dermal

General population

Yes

Release of D4 into
surface water and
indirect partitioning
to sediment and
bioaccumulation
exposure pathways to
the general
population will be
analyzed.







Drinking water
via surface or
groundwater

Oral
Dermal

Inhalation (e.g.,
showering)

General population

Yes

Release of D4 into
surface water and
indirect partitioning
to drinking water is
an expected exposure
pathway.

Page 123 of 124


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Life Cycle
Stage

Category

Release

Exposure
Pathway/Media

Exposure Route(s)

Receptor/
Population

Plans to
Evaluate

Rationale







Biosolids:
application to soil
and/or migration
to groundwater
and/or surface
water

Oral (e.g., ingestion of
soil)

Inhalation

General population

Yes

EPA plans to analyze
the pathway from
biosolids to the
general population
and to aquatic and
terrestrial species.



Wastewater or
liquid wastes

Industrial pre-
treatment and
wastewater
treatment, or
POTW

TBD

Aquatic and
terrestrial receptors

Yes

All

Air

Inhalation

General population

Yes

EPA plans to analyze
the pathway from
municipal landfills
and other land
disposal to the
general population,
receptors.







Leachate to soil,
groundwater
and/or migration
to surface water

Oral
Dermal

General population

Yes

EPA plans to analyze
the pathway from
municipal landfills
and other land
disposal to the
general population,
aquatic, and
terrestrial receptors.

Disposal

Solid and
liquid wastes

Municipal
landfill and
other land
disposal

TBD

Aquatic and
terrestrial receptors





Air

Inhalation

General population

Yes

EPA plans to analyze
the pathway from
municipal landfills
and other land
disposal to the
general population,
receptors.

Page 124 of 124


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