[Federal Register Volume 90, Number 178 (Wednesday, September 17, 2025)]
[Notices]
[Pages 44821-44822]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-17967]
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ENVIRONMENTAL PROTECTION AGENCY
[EPA-HQ-OPPT-2018-0443; FRL-12964-01-OCSPP]
Octamethylcyclotetrasiloxane (Cyclotetrasiloxane,
2,2,4,4,6,6,8,8-octamethyl-) (D4); Draft Risk Evaluation Under the
Toxic Substances Control Act (TSCA); Notice of Availability and Request
for Comment
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: The Environmental Protection Agency (EPA or Agency) is
announcing the availability of and seeking public comment on a draft
risk evaluation under the Toxic Substances Control Act (TSCA) for
Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-
octamethyl-) (D4) (CASRN 556-67-2). The purpose of risk evaluations
under TSCA is to determine whether a chemical substance presents an
unreasonable risk of injury to health or the environment under the
conditions of use (COUs), including unreasonable risk to potentially
exposed or susceptible subpopulations identified as relevant to the
risk evaluation by EPA, and without consideration of costs or non-risk
factors. EPA used the best available science to prepare this draft risk
evaluation and to preliminarily determine, based on the weight of
scientific evidence, that D4 poses unreasonable risk to human health
and the environment driven primarily by certain conditions of use
analyzed in the draft risk evaluation.
DATES: Comments must be received on or before November 17, 2025.
ADDRESSES: Submit your comments, identified by docket identification
(ID) number EPA-HQ-OPPT-2018-0443, online at https://www.regulations.gov. Follow the online instructions for submitting
comments. Do not submit electronically any information you consider to
be Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Additional instructions on
commenting and visiting the docket, along with more information about
dockets generally, is available at https://www.epa.gov/dockets.
FOR FURTHER INFORMATION CONTACT:
For technical information: Scott Drewes, Existing Chemical Risk
Management Division (7404M), Office of Pollution Prevention and Toxics,
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington,
DC 20460-0001; telephone number: (202) 564-8833; email address:
[email protected].
For general information: The TSCA-Hotline, Goodwill of the Finger
Lakes, 422 South Clinton Ave., Rochester, NY 14620; telephone number:
(202) 554-1404; email address: [email protected].
SUPPLEMENTARY INFORMATION:
I. Executive Summary
A. Does this action apply to me?
This action is directed to the public in general and may be of
particular interest to those involved in the manufacture (defined under
TSCA section 3(9) to include import), processing, distribution, use,
and disposal of D4, related industry trade organizations, non-
governmental organizations with an interest in human and environmental
health, state and local governments, Tribal Nations, and/or those
interested in the assessment of risks involving chemical substances and
mixtures regulated under TSCA. As such, the Agency has not attempted to
describe all the specific entities that this action might apply to. If
you need help determining applicability, consult the technical contact
listed under FOR FURTHER INFORMATION CONTACT.
B. What is the Agency's authority for taking this action?
The Agency is conducting this risk evaluation under TSCA section 6,
15 U.S.C. 2605, which requires that EPA conduct risk evaluations on
chemical substances and identifies the minimum components EPA must
include in the risk evaluations. Each risk evaluation must be conducted
consistent with the best available science, be based on the weight of
the scientific evidence, and consider reasonably available information,
and not consider costs or non-risk factors. 15 U.S.C. 2625(h), (i), and
(k). See also the implementing procedural regulations at 40 CFR part
702.
C. What action is the Agency taking?
EPA is announcing the availability of and seeking public comment on
a draft risk evaluation under TSCA for D4. This draft risk evaluation
was developed in response to a manufacturer request. The purpose of
risk evaluations under TSCA is to determine whether a chemical
substance presents an unreasonable risk of injury to health or the
environment under the conditions of use, including unreasonable risk to
potentially exposed or susceptible subpopulations identified as
relevant to the risk evaluation by EPA, and without consideration of
costs or non-risk factors. EPA has used the best available science to
prepare this draft risk evaluation and, based on the weight of
scientific evidence, to preliminarily determine that D4 poses
unreasonable risk to human health and/or the environment.
D. What should I consider as I prepare my comments?
1. Submitting CBI. Do not submit CBI to EPA through https://www.regulations.gov or email. If you wish to include CBI in your
comment, please follow the applicable instructions at https://www.epa.gov/dockets/commenting-epa-dockets#rules and clearly mark the
information that you claim to be CBI. Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR
parts 2 and 703, as applicable.
2. Tips for preparing your comments. When preparing and submitting
your comments, see the commenting tips at https://www.epa.gov/dockets/commenting-epa-dockets.
II. Background
A. What is D4?
D4 is a common name for octamethylcyclotetrasiloxane (CASRN 556-67-
2). It is a colorless, volatile, oily liquid primarily used to make
silicone chemicals. D4 commercial uses include but are not limited to
adhesives and sealants, automotive care products, paints and coatings,
and other plastic and rubber products. D4 is also used as an ingredient
in consumer products (i.e., cosmetics, medical devices, and food
contact materials) regulated by the Federal Food, Drug, and Cosmetic
Act (FFDCA) [21 U.S.C. 321]. D4 is not reported to the Toxics Release
Inventory, National Emission Inventory, or to the Discharge Monitoring
Report system. D4 is found in various environmental media including
air, water, sediment, soil, and biota.
B. Summary of Activities for the Risk Evaluation of D4
On March 19, 2020, EPA received a manufacturer request, pursuant to
40 CFR 702.37, to conduct a risk evaluation for D4 (Docket ID: EPA-HQ-
OPPT-2018-0443) through the American Chemistry Council's Silicones
[[Page 44822]]
Environmental, Health, and Safety Center. (Ref. 1) In October 2020, EPA
granted the manufacturer request for risk evaluation for D4. In
September 2021, EPA published and sought public comment on the draft
scope of the D4 risk evaluation (Ref. 2), and, after considering public
comments, issued the final scope in March 2022 (Ref. 3). These
documents, other supporting documents, and public comments are in the
docket at https://www.regulations.gov.
Additionally, in 2014, EPA issued an enforceable consent agreement
(ECA) requiring five manufacturers of D4 to submit testing data to help
the agency better understand the amount of D4 released into the
environment and the quantity of D4 in water, sediment and aquatic
organisms. The signatory companies completed the ECA testing
requirements in September 2017. The information gathered by the ECA was
used in conjunction with other available data to assess exposures and
risks due to environmental releases from D4. The final test report can
be found in multiple sections in the docket (EPA-HQ-OPPT-2012-0209).
III. Request for Comment
EPA seeks feedback on the assessment of risk presented in the draft
risk evaluation for D4, a copy of which is available in the docket, and
encourages all potentially interested parties, including individuals,
governmental and non-governmental organizations, non-profit
organizations, academic institutions, research institutions, and
private sector entities to comment on the draft risk evaluation. To the
extent possible, the Agency asks commenters to please cite any public
data related to or that support comments provided, and to the extent
permissible, describe any supporting data that is not publicly
available.
EPA welcomes specific input on each section of the draft risk
evaluation, particularly input on the following:
evaluation and use of the D4 physiologically based
pharmacokinetic model;
identification of hazards relevant to human health and
ecological risk assessment;
whether and how exposure controls and personal protective
equipment are used for each of the COUs;
information on environmental release of D4, including
media of release and facility-specific receiving waterbodies;
information to inform estimates of dermal exposures for
workers;
information to inform exposures of occupational non-users
in the assessment;
handling of uncertainties associated with exposure and
release assessments;
bioaccumulation, bioconcentration, biomagnification, and
potential trophic transfer, including the selection of the
bioconcentration factor to estimate human exposure from fish
consumption;
consideration of aggregate exposure and risk; and,
any other information that may inform the assumptions used
for modeling each of the COUs.
IV. Next Steps
EPA will consider comments received from the public and SACC on the
draft risk evaluation and will issue the final risk evaluation for D4.
A separate forthcoming Federal Register notice will announce the peer
review by the SACC.
Under TSCA section 6, EPA must determine in the final risk
evaluation, based on the weight of scientific evidence, whether or not
the chemical presents an unreasonable risk to health or the environment
under the chemical's conditions of use. This includes consideration of
risks to potentially exposed susceptible subpopulations (PESS) who may
be at greater risks than the general population, such as children and
workers. TSCA prohibits EPA from considering non-risk factors (e.g.,
costs/benefits) during risk evaluation.
If EPA determines that a chemical presents an unreasonable risk to
health or the environment, the chemical will move to risk management
action under TSCA section 6(a) for the relevant conditions of use.
For more information about the TSCA risk evaluation process for
existing chemicals, go to https://www.epa.gov/assessing-and-managing-chemicals-under-tsca.
V. References
The following is a listing of the documents that are specifically
referenced in this document. The docket includes these documents and
other information considered by EPA, including documents that are
referenced within the documents that are included in the docket, even
if the referenced document is not physically located in the docket. For
assistance in locating these other documents, please consult the person
listed under FOR FURTHER INFORMATION CONTACT.
1. EPA. Manufacturer Request for Risk Evaluation under the Toxic
Substances Control Act: Octamethylcyclotetra-siloxane (D4): Notice
of Availability. Federal Register. 85 FR 36586, June 17, 2020 (FRL-
10010-49).
2. EPA. Octamethylcyclotetra-Siloxane (D4); Draft Scope of the Risk
Evaluation to Be Conducted Under the Toxic Substances Control Act;
Notice of Availability and Request for Comments. Federal Register.
86 FR 50347, September 8, 2021 (FRL-8850-01-OCSPP).
3. EPA. Final Scope of the Risk Evaluation to Be Conducted Under the
Toxic Substances Control Act: Octamethylcyclotetra-siloxane (D4).
Notice. Federal Register. 87 FR 12696, March 07, 2022 (FRL-8850-02-
OCSPP).
Authority: 15 U.S.C. 2601 et seq.
Dated: September 12, 2025.
Nancy B. Beck,
Principal Deputy Assistant Administrator, Office of Chemical Safety and
Pollution Prevention.
[FR Doc. 2025-17967 Filed 9-16-25; 8:45 am]
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