Document ID: EPA-HQ-OPPT-2022-0905-0032
Agency: epa
Document Type: Notice
Title: 1,4-Dioxane; Draft Supplement to the TSCA Risk Evaluation; Science Advisory Committee on Chemicals (SACC) Meeting; Notice of Meeting and Request for Comment
Posted Date: 2023-07-11T04:00Z

[Federal Register Volume 88, Number 130 (Monday, July 10, 2023)]
[Notices]
[Pages 43562-43565]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-14445]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OPPT-2022-0905; FRL-10798-02-OCSPP]

1,4-Dioxane; Draft Supplement to the TSCA Risk Evaluation; 
Science Advisory Committee on Chemicals (SACC) Meeting; Notice of 
Meeting 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 soliciting public comment on the 
``2023 Draft Supplement to the 1,4-Dioxane Risk Evaluation'' prepared 
under the Toxic Substances Control Act (TSCA) that is being submitted 
to the Science Advisory Committee on Chemicals (SACC) for peer review. 
The draft supplement is available for public review and comment and is 
submitted to the SACC for peer review. The SACC will consider and 
review the draft supplement at a 4-day virtual public meeting that was 
previously announced in the Federal Register of March 23, 2023. The 
virtual public meeting will be held on September 12-15, 2023, via a 
webcast platform such as ``Zoomgov.com'' and audio teleconference.

DATES: The following is a chronological listing of the dates for the 
specific activities that are described in more detail under 
SUPPLEMENTARY INFORMATION.
    September 1, 2023--Deadline for submitting a request for special 
accommodations to allow EPA time to process the request before the 
meeting.
    September 8, 2023--Deadline for providing written comments on the 
draft supplement.
    September 8, 2023--Deadline for registering to be listed on the 
meeting agenda to make oral comments during the virtual meeting.
    September 15, 2023--Deadline for those not making oral comments to 
register to receive the links to observe the meeting.

ADDRESSES: 
    To comment: Submit written comments, identified by docket 
identification (ID) number EPA-HQ-OPPT-2022-0905, through the Federal 
eRulemaking Portal at https://www.regulations.gov. Follow the online 
instructions for submitting comments. Do not electronically submit any 
information you consider to be Confidential Business Information (CBI)

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or other information whose disclosure is restricted by statute. 
Copyrighted material will not be posted without explicit permission 
from the copyright holder. Members of the public should also be aware 
that personal information included in any written comments may be 
posted on the internet at https://www.regulations.gov. Additional 
information on commenting or visiting the docket, along with more 
information about dockets generally, is available at https://www.epa.gov/dockets.
    To register for the meeting: For information on how to register and 
access the virtual public meeting, please refer to the SACC website at 
https://www.epa.gov/tsca-peer-review. EPA intends to announce 
registration instructions on the SACC website by mid-August of 2023. 
You may also subscribe to the following listserv for alerts regarding 
this and other SACC-related activities at https://public.govdelivery.com/accounts/USAEPAOPPT/subscriber/new?topic_id=USAEPAOPPT_101.
    To request special accommodations: For information on access or 
services for individuals with disabilities, and to request 
accommodation for a disability, please contact the Designated Federal 
Official (DFO) listed under FOR FURTHER INFORMATION CONTACT.

FOR FURTHER INFORMATION CONTACT: The DFO, Dr. Alaa Kamel, Mission 
Support Division (7602M), Office of Program Support, Office of Chemical 
Safety and Pollution Prevention, Environmental Protection Agency; 
telephone number: (202) 564-5336 or SACC main office number: (202) 564-
8450; email address: [email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. What action is the Agency taking?

    EPA is announcing the availability of and soliciting public comment 
on the ``2023 Draft Supplement to the 1,4-Dioxane Risk Evaluation.'' 
EPA is also announcing a 4-day virtual public meeting on September 12-
15, 2023, for the SACC to consider and review the draft supplement. 
This September 2023 meeting was previously announced in the Federal 
Register of March 23, 2023 (88 FR 17566 (FRL-10798-01-OCSPP)). EPA will 
be soliciting comments from the SACC on the methodologies utilized in 
the 2023 Draft Supplement to the 1,4-Dioxane Risk Evaluation that have 
not been previously peer reviewed. EPA is also releasing for public 
comment an updated risk determination for 1,4-dioxane (see docket ID 
No. EPA-HQ-OPPT-2016-0723). EPA is not soliciting comments from the 
SACC on the risk determination for 1,4-dioxane.
    This document provides instructions for accessing the materials 
provided to the SACC, submitting written comments, and registering to 
provide oral comments and attend the virtual meeting.

B. What is the Agency's authority for taking this action?

    The SACC was established by EPA in 2016 in accordance with the 
Toxic Substances Control Act (TSCA), 15 U.S.C. 2625(o), to provide 
independent advice and expert consultation, at the request of the 
Administrator, with respect to the scientific and technical aspects of 
issues relating to the implementation of TSCA. The SACC operates in 
accordance with the Federal Advisory Committee Act (FACA), 5 U.S.C. 10, 
and supports activities under the TSCA, 15 U.S.C. 2601 et seq., the 
Pollution Prevention Act (PPA), 42 U.S.C. 13101 et seq., and other 
applicable statutes.

C. Does this action apply to me?

    This action is directed to the public in general. This action may, 
however, be of interest to those involved in the manufacture, 
processing, distribution, and disposal of chemical substances and 
mixtures, and/or those interested in the assessment of risks involving 
chemical substances and mixtures regulated under TSCA. Since other 
entities may also be interested, the Agency has not attempted to 
describe all the specific entities that may be affected by this action.

D. What should I consider as I submit my comments to EPA?

1. Submitting CBI
    Contact the DFO listed under FOR FURTHER INFORMATION CONTACT for 
instructions before submitted CBI or other sensitive information. Do 
not submit this information to EPA electronically (e.g., through 
https://www.regulations.gov or email). Clearly mark the part or all of 
the information that you claim to be CBI. For confidential information 
in a disk or CD-ROM that you mail to EPA, mark the outside of the disk 
or CD-ROM as CBI and then identify electronically within the disk or 
CD-ROM the specific information that is claimed as CBI. In addition to 
one complete version of the comment that includes information claimed 
as CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2.
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. See also 
the instructions in Unit III.C.

II. Background

A. What is the purpose of the SACC?

    The SACC provides independent scientific advice and recommendations 
to the EPA on the scientific and technical aspects of risk assessments, 
methodologies, and pollution prevention measures and approaches for 
chemicals regulated under TSCA. The SACC is comprised of experts in 
toxicology; environmental risk assessment; exposure assessment; and 
related sciences (e.g., synthetic biology, pharmacology, biotechnology, 
nanotechnology, biochemistry, biostatistics, physiologically based 
pharmacokinetic modeling (PBPK), computational toxicology, 
epidemiology, environmental fate, and environmental engineering and 
sustainability). The SACC currently consists of 19 members. When 
needed, the committee will be assisted by ad hoc reviewers with 
specific expertise in the topics under consideration.

B. Why did EPA develop these documents?

    TSCA requires EPA to conduct risk evaluations on prioritized 
chemical substances and identifies the minimum components EPA must 
include in all chemical substance risk evaluations. The purpose of 
conducting risk evaluations is to determine whether a chemical 
substance presents an unreasonable risk to human health or the 
environment under the conditions of use. These evaluations include 
assessing unreasonable risks to relevant potentially exposed or 
susceptible subpopulations. As part of this process, EPA: (1) 
integrates hazard and exposure assessments using the best available 
science that is reasonably available to assure decisions are based on 
the weight of the scientific evidence; and (2) conducts peer review for 
risk evaluation approaches that have not been previously peer reviewed.
    1,4-Dioxane was one of the first 10 chemical substances undergoing 
the TSCA risk evaluation process after passage of the Frank R. 
Lautenberg Chemical Safety for the 21st Century Act, which amended TSCA 
in 2016. 1,4-Dioxane is primarily used as a solvent in a variety of 
commercial and

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industrial applications such as the manufacture of other chemicals 
(e.g., adhesives, sealants) or as a processing aid or laboratory 
chemical. Although there are no direct consumer uses of 1,4-dioxane, it 
is present as a byproduct in commercial and consumer products from 
several manufacturing processes, including ethoxylation, sulfonation, 
sulfation, and esterification.
    In the 2019 Draft Risk Evaluation for 1,4-Dioxane (see https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0011), EPA reviewed 
the exposures and hazards of 1,4-dioxane direct industrial and 
commercial uses assessing risk from occupational exposures and surface 
water exposures to environmental organisms. This assessment, which 
included the physical and chemical properties, lifecycle information, 
environmental fate and transport information, and hazard identification 
and dose-response analysis was reviewed by the SACC. The Agency 
considered the SACC feedback and is not seeking additional review at 
this time as this information has not changed.
    In November of 2020, EPA released for public comment a Draft 
Supplement to the 2019 Draft Risk Evaluation (see https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0067). The November 
2020 Draft Supplement assessed eight conditions of use (COUs) of 1,4-
dioxane as a byproduct in consumer products and general population 
exposure from incidental contact with surface water. The Agency 
determined that the additional analysis did not warrant SACC review.
    The 2019 Draft Risk Evaluation and 2020 Draft Supplement were both 
incorporated into the final Risk Evaluation for 1,4-Dioxane released in 
December 2020 (see https://www.epa.gov/sites/default/files/2020-12/documents/1._risk_evaluation_for_14-dioxane_casrn_123-91-1.pdf). After 
its release, EPA determined an additional supplement to the final Risk 
Evaluation for 1,4-Dioxane was needed to consider critical exposure 
pathways not previously assessed. Specifically, the 2023 Draft 
Supplement includes evaluation of additional conditions of use in which 
1,4-dioxane is present as a byproduct in industrial processes and 
commercial products and evaluates risks from general population 
exposures to 1,4-dioxane released to ambient surface water and 
groundwater, ambient air, and land. To evaluate these additional 
exposure pathways, the Agency used new methods and novel applications 
of existing methods. These new methods described below have not been 
the subject of public comment or peer review for applications in TSCA 
risk evaluations.
    In this 2023 Draft Supplement, EPA is relying on the physical and 
chemical properties, lifecycle information, environmental fate and 
transport information, and hazard identification and dose-response 
analysis presented in the December 2020 final Risk Evaluation for 1,4-
Dioxane, thus, EPA is not seeking feedback on these topics. However, 
EPA is seeking review of the methodologies listed below that have not 
been previously peer reviewed and are utilized in this 2023 Draft 
Supplement to the 1,4-Dioxane Risk Evaluation.
1. EPA Applied Monte Carlo Modeling in the Assessment of 1,4-Dioxane 
Occupational Exposures and Environmental Releases
    The Agency has utilized Monte Carlo approaches in TSCA risk 
evaluations previously for specific conditions of use; however, the 
application of Monte Carlo methods in the ``2023 Draft Supplement to 
the 1,4-Dioxane Risk Evaluation'' was expanded to capture additional 
exposure and release models for additional conditions of use. The 
expanded application of these methods incorporates randomness and 
variability to improve the representativeness of the resulting model 
outputs. This was done to further improve exposure and release 
estimates and is in response to previous SACC review comments received 
on the first 10 chemical risk evaluations conducted under amended TSCA.
2. EPA Assessed Hydraulic Fracturing as a Condition of Use
    This evaluation required consideration of new field operations data 
that have not yet been considered in TSCA risk evaluations to estimate 
occupational exposures and environmental releases from these 
operations. EPA has developed a new generic exposure scenario for 
hydraulic fracturing and applied it in the 2023 Draft Supplement along 
with the Monte Carlo modeling to estimate a range of potential 
releases.
3. EPA Assessed the Ambient Air Pathway To Determine Exposures and 
Associated Risks to Fenceline Communities (a Subset of the General 
Population)
    The Agency assessed general population exposures via the inhalation 
route through both single- and multi-year analyses. The single-year 
analysis utilized the Fenceline 1.0 methodology described in the ``EPA 
Toxic Substances Control Act (TSCA) Screening Level Approach for 
Assessing Ambient Air and Water Exposures to Fenceline Communities,'' 
previously peer reviewed by the SACC (see, EPA (2022). Peer Review of 
the EPA TSCA Screening Level approach for Assessing Ambient Air and 
Water Exposures to Fenceline Communities March 15-17, 2022. https://www.regulations.gov/docket/EPA-HQ-OPPT-2021-0415/document.) EPA 
quantitatively characterized exposures and risks to communities in 
proximity to multiple facilities releasing 1,4-dioxane to air.
4. EPA Assessed General Population Exposures via Drinking Water Sourced 
From Groundwater and Surface Water
    Although the 2020 1,4-dioxane risk evaluation considered incidental 
oral and dermal exposures to surface water, the 2020 analysis did not 
consider drinking water exposures through sourcing of 1,4-dioxane 
contained in surface water or groundwater.
a. Surface Water
     1,4-Dioxane concentrations in surface water reported in 
the 2023 draft supplemental risk evaluation were modeled based on known 
facility and publicly owned treatment works releases directly to 
surface water. This methodology is generally consistent with what was 
previously done to aquatic exposures and presented in the draft 
Fenceline 1.0 methodology previously reviewed by the SACC. However, 
this analysis was modified to include consideration of multiple years 
of release data, as recommended by SACC, and integrated NHDPlus flow 
networks and flows to modernize approaches previously utilized in TSCA 
risk evaluations. This assessment is the first time the modified 
approach has been employed in a TSCA risk evaluation
     1,4-Dioxane concentrations resulting from consumer and 
commercial down-the-drain releases of 1,4-dioxane through publicly 
owned treatment works to surface water were estimated. EPA used the 
Stochastic Human Exposure and Dose Simulation Model (SHEDS) for high-
throughput (HT) (SHEDS-HT) model (see Environ. Sci. Technol. 2014, 48, 
21, 12750-12759) predictions to estimate down-the-drain disposals 
(Isaacs, 2014). SHEDS-HT was developed by EPA under the ExpoCast 
program for evaluating chemicals based on the potential for 
biologically relevant human exposure. This is the first TSCA risk 
evaluation incorporating down-the-drain estimates based on SHEDS-HT 
model predictions and is the first time the down-the-drain model has 
been

[[Page 43565]]

used for one of the first 10 chemical risk evaluations conducted under 
amended TSCA.
     1,4-Dioxane concentrations in surface water were modeled 
based on multiple upstream sources, including releases from facilities 
and publicly owned treatment works and down-the-drain releases. In 
addition, EPA compared the modeled concentrations to drinking water 
monitoring data for community water systems. This approach to 
considering the contribution of multiple sources to drinking water 
exposures is novel. EPA has not previously considered multiple sources 
of releases when estimating exposure concentrations in surface water 
for a chemical risk evaluation under TSCA.
b. Groundwater
     1,4-Dioxane concentrations in groundwater were modeled for 
two disposal pathways by applying the Delisting Risk Assessment 
Software (DRAS) model in a novel way. DRAS is a multi-pathways model 
developed by the EPA that calculates the potential human health risks 
associated with disposing of a specific facility's given waste stream 
in a landfill or surface impoundment. (See U.S. EPA. (2020). Hazardous 
Waste Delisting Risk Assessment Software Version 4. Lenexa, KS: EPA 
Region 6. https://www.epa.gov/hw/hazardous-waste-delisting-risk-assessment-software-dras.) DRAS was specifically designed to address 
the Criteria for Listing Hazardous Waste. The 2023 Draft Supplement to 
the 1,4-Dioxane Risk Evaluation presents a novel application of this 
model and the first application in a TSCA chemical risk evaluation. 
Specifically, EPA compared the modeled concentrations to monitoring 
data from groundwater contaminations around the nation to consider if 
they are within a reasonable range.
    EPA is also seeking review of the overall synthesis of the results 
of these novel methodologies and the integration of the results into 
the 1,4-Dioxane Risk Evaluation. Feedback from this review will be 
considered in the development of the final supplement to the 1,4-
dioxane risk evaluation. In addition, SACC reviewer feedback may help 
refine EPA's methods for conducting release assessments and evaluating 
general population exposures in risk evaluations of other chemicals 
under TSCA.

III. Virtual Public Meeting of the SACC

A. What is the purpose of this public meeting?

    The purpose of the 4-day virtual public meeting is the SACC peer 
review of the methodologies that have not been previously peer reviewed 
and are utilized in the 2023 Draft Supplement. Feedback from this 
review will be considered in the development of the final Supplement to 
the Risk Evaluation for 1,4-Dioxane. In addition, SACC reviewer 
feedback may help refine EPA's methods for conducting release 
assessments and evaluating general population exposures in risk 
evaluations of other chemicals under TSCA.
    EPA intends to provide a meeting agenda for each day of the 
meeting, and as needed, may provide updated times for each day in the 
meeting agenda that will be posted in the docket and on the SACC 
website.

B. How can I access the documents submitted for review to the SACC?

    The 2023 Draft Supplement and related documents, including 
background documents, related supporting materials, and draft charge 
questions provided to the SACC, are available in the docket. As 
additional background materials become available and are provided to 
the SACC, EPA will include those additional background documents (e.g., 
SACC members and consultants participating in this meeting and the 
meeting agenda) in the docket. All of these documents will be available 
through https://www.regulations.gov (docket ID No. EPA-HQ-OPPT-2022-
0905) and through links on the SACC website at https://www.epa.gov/tsca-peer-review.
    After the public meeting, the SACC will prepare meeting minutes and 
a final report document summarizing its recommendations to the EPA. 
This document will also be available in the docket and the SACC 
website.

C. How can I provide comments for the SACC's consideration?

    To ensure proper receipt of comments it is imperative that you 
identify docket ID No. EPA-HQ-OPPT-2022-0905 in the subject line on the 
first page of your comments and follow the instructions in Unit I.D. 
and in this unit.
1. Written Comments
    The Agency encourages written comments for this meeting be 
submitted by the deadlines set in the DATES section of this document 
and following the instructions in this document.
2. Oral Comments
    The Agency encourages each individual or group wishing to make 
brief oral comments to the SACC during the peer review virtual public 
meeting to follow the registration instructions that will be announced 
on the SACC website by mid-August of 2023. Oral comments before the 
SACC during the peer review virtual public meeting are limited to 5 
minutes. In addition, each speaker should submit a written copy of 
their oral comments and any supporting materials (e.g., presentation 
slides) to the DFO prior to the meeting for distribution to the SACC by 
the DFO.

D. How can I participate in the virtual public meeting?

    The virtual public meeting will be held via a webcast platform such 
as ``Zoomgov.com'' and audio teleconference. You must register online 
to receive the webcast meeting link and audio teleconference 
information. Please follow the registration instructions that will be 
announced on the SACC website.
    Authority: 15 U.S.C. 2625(o); 5 U.S.C 10.

    Dated: July 3, 2023.
Michal Freedhoff,
Assistant Administrator, Office of Chemical Safety and Pollution 
Prevention.
[FR Doc. 2023-14445 Filed 7-7-23; 8:45 am]
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