[Federal Register Volume 88, Number 56 (Thursday, March 23, 2023)]
[Notices]
[Pages 17566-17569]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-05982]


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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OPPT-2022-0905; FRL-10798-01-OCSPP]


Science Advisory Committee on Chemicals (SACC); Draft Supplement 
to the 1,4-Dioxane Risk Evaluation; Request for Nominations of ad hoc 
Expert Reviewers and Notice of Public Meeting

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: The Environmental Protection Agency (EPA or ``Agency'') is 
seeking public nominations of scientific and technical experts that EPA 
can consider for service as ad hoc reviewers assisting the Science 
Advisory Committee on Chemicals (SACC) with the peer review of the 
``2023 Draft Supplement to the 1,4-Dioxane Risk Evaluation.'' The draft 
supplement will be released for public review and comment in June of 
2023. EPA is also planning to submit the draft supplement to the SACC 
for peer review and is scheduling a 4-day virtual public meeting for 
the SACC to consider and review the draft supplement in September of 
2023.

DATES: Submit your nominations on or before April 24, 2023.

ADDRESSES: 
    Nominations: Submit your nominations to the Designated Federal 
Official (DFO) listed under FOR FURTHER INFORMATION CONTACT.
    Special accommodations: For information on access or services for 
individuals with disabilities, and to request accommodation for a 
disability, please contact the DFO listed under FOR FURTHER INFORMATION 
CONTACT.

FOR FURTHER INFORMATION CONTACT: 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 call the SACC main office 
at (202) 564-8450; email address: [email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. What action is the Agency taking?

    The Agency is seeking public nominations of scientific and 
technical experts that the EPA can consider for service as ad hoc 
reviewers assisting the SACC with the peer review of the ``2023 Draft 
Supplement to the 1,4-Dioxane Risk Evaluation.'' EPA is also planning a 
4-day virtual public meeting for the SACC to consider and review the 
draft supplement. EPA will be soliciting comments from the SACC on the 
methodologies utilized in the draft 2023 1,4-dioxane supplemental risk 
evaluation that have not been previously peer reviewed.
    This document provides instructions for submitting nominations for 
EPA to consider for ad hoc reviewers. EPA will publish a separate 
document in the Federal Register in June of 2023 to announce the 
availability of the draft supplement and solicit public comments. 
Additional instructions and information regarding the virtual public 
meeting will be provided at that time.

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 nominations to EPA?

    Submitting CBI. Do not submit CBI or other sensitive information to 
EPA through https://www.regulations.gov or email. If your nomination 
contains any information that you consider to be CBI or otherwise 
protected, please contact the DFO listed under FOR FURTHER INFORMATION 
CONTACT to obtain special instructions before submitting that 
information.

II. Nominations for ad hoc Reviewers

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 17 members. When 
needed, the committee will be assisted by ad hoc reviewers with 
specific expertise in the topics under consideration.

B. Why is EPA seeking nominations for ad hoc reviewers?

    As part of a broader process for developing a pool of candidates 
for SACC peer reviews, EPA is asking the public and stakeholder 
communities for nominations of scientific and technical experts that 
EPA can consider as prospective candidates for service as ad hoc 
reviewers assisting the SACC with the peer reviews. Any interested 
person or organization may nominate qualified individuals for 
consideration as prospective candidates for this review by following 
the instructions provided in this document. Individuals may also self-
nominate.
    Those who are selected from the pool of prospective candidates will 
be invited to attend the public meeting and to participate in the 
discussion of key issues and assumptions at the meeting. In addition, 
they will be asked to review

[[Page 17567]]

and to help finalize the meeting minutes.

C. What expertise is sought for this peer review?

    Individuals nominated for this SACC peer review, should have 
expertise in one or more of the following areas: Engineering 
(experience in environmental exposure release from industrial sources 
for review of Monte Carlo release assessment methods, risk assessment 
experience preferred); Industrial Hygiene (experience with evaluating 
the application of occupational exposure modeling approaches and 
monitoring data for industrial and commercial operations); Statistics 
(experience in water quality data for review of novel application of 
Monte Carlo methods in release assessment and water model); Exposure 
science and contaminant hydrology (experience in aquatic monitoring and 
modeling for groundwater and surface water with background in risk 
assessment); Exposure science with experience in air modeling (for 
review of air exposure analysis); Petroleum engineering (experience in 
evaluating sources of environmental releases from hydraulic fracturing 
operations); Risk assessment (experience in chemicals and environmental 
fate of chemicals for review of exposure factors, averaging time 
assumptions, etc. with background in risk assessment). Nominees should 
be scientists who have sufficient professional qualifications, 
including training and experience, to be capable of providing expert 
comments on the scientific issues for this review.

D. How do I make a nomination?

    By the deadline indicated under DATES, submit your nomination to 
the DFO listed under FOR FURTHER INFORMATION CONTACT. Each nomination 
should include the following information: Contact information for the 
person making the nomination; name, affiliation, and contact 
information for the nominee; and the disciplinary and specific areas of 
expertise of the nominee.

E. Will ad hoc reviewers be subjected to an ethics review?

    SACC members and ad hoc reviewers are subject to the provisions of 
the Standards of Ethical Conduct for Employees of the Executive Branch 
at 5 CFR part 2635, conflict of interest statutes in Title 18 of the 
United States Code and related regulations. In anticipation of this 
requirement, prospective candidates for service on the SACC will be 
asked to submit confidential financial information which shall fully 
disclose, among other financial interests, the candidate's employment, 
stocks and bonds, and where applicable, sources of research support. 
EPA will evaluate the candidates' financial disclosure forms to assess 
whether there are financial conflicts of interest, appearance of a loss 
of impartiality, or any prior involvement with the development of the 
documents under consideration (including previous scientific peer 
review) before the candidate is considered further for service on the 
SACC.

F. How will EPA select the ad hoc reviewers?

    The selection of scientists to serve as ad hoc reviewers for the 
SACC is based on the function of the Committee and the expertise needed 
to address the Agency's charge to the Committee. No interested 
scientists shall be ineligible to serve by reason of their membership 
on any other advisory committee to a federal department or agency or 
their employment by a federal department or agency, except EPA. Other 
factors considered during the selection process include availability of 
the prospective candidate to fully participate in the Committee's 
reviews, absence of any conflicts of interest or appearance of loss of 
impartiality, independence with respect to the matters under review, 
and lack of bias. Although financial conflicts of interest, the 
appearance of loss of impartiality, lack of independence, and bias may 
result in non-selection, the absence of such concerns does not assure 
that a candidate will be selected to serve on the SACC.
    Numerous qualified candidates are often identified for SACC 
reviews. Therefore, selection decisions involve carefully weighing a 
number of factors including the candidates' areas of expertise and 
professional qualifications, and achieving an overall balance of 
different scientific perspectives across reviewers. The Agency will 
consider all nominations of prospective candidates for service as ad 
hoc reviewers for the SACC that are received on or before the date 
listed in the DATES section of this document. However, the final 
selection of ad hoc reviewers is a discretionary function of the 
Agency. At this time, EPA anticipates selecting 10-15 ad hoc reviewers 
to assist the SACC in their review of the designated topic.
    EPA plans to make a list of candidates under consideration as 
prospective ad hoc reviewers for this review available for public 
comment in late May or early June 2023. The list will be available in 
the docket at https://www.regulations.gov (docket ID number EPA-HQ-
OPPT-2022-0905) and through the SACC website. You may also subscribe to 
the following listserv for alerts regarding this and other SACC-related 
activities: https://public.govdelivery.com/accounts/USAEPAOPPT/subscriber/new?topic_id=USAEPAOPPT_101.

III. Virtual Public Meeting of the SACC

A. What is the purpose of this public meeting?

    The focus 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 1,4-dioxane supplemental 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.
    In addition, EPA intends to publish a separate document in the 
Federal Register to announce the availability of and solicit public 
comment on the draft supplement, at which time EPA will provide 
instructions for submitting written comments and registering to provide 
oral comments at the peer review meeting planned for September. EPA 
also 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. Why did EPA develop these documents?

    TSCA requires the U.S. Environmental Protection Agency (EPA or the 
Agency) 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

[[Page 17568]]

approaches that have not been previously peer reviewed.
    1,4-Dioxane is 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. 1,4-Dioxane is primarily used as a solvent in a variety of 
commercial and 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 and 
commercial uses of 1,4-dioxane, it is also produced as a byproduct in 
commercial and consumer products from several manufacturing processes, 
including ethoxylation, sulfonation, sulfation, and esterification.
    In the 2019 draft 1,4-dioxane risk evaluation, EPA reviewed the 
exposures and hazards of 1,4-dioxane direct 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 October of 2020, a supplement to the draft 1,4-dioxane risk 
evaluation was released for public comment. The October 2020 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 and 2020 supplement were both incorporated into the 
final Risk Evaluation for 1,4-Dioxane published December 2020. After 
publication, 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 more recent 
supplement (2023) 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 the 2023 supplemental, 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 final Risk Evaluation for 1,4-Dioxane, thus, 
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 the 2023 1,4-dioxane supplemental risk 
evaluation.
    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 draft 2023 1,4-dioxane 
supplemental 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 risk evaluations.
    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 draft 1,4-dioxane 
supplemental risk evaluation along with the Monte Carlo modeling to 
estimate a range of potential releases.
    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 ``Draft TSCA screening level approach for assessing 
ambient air and water exposures to fenceline communities, Version 1.0'' 
(see ``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) previously reviewed by the SACC. Although that 
methodology has been peer reviewed, the results from application of the 
methodology to 1,4-dioxane is first presented in the 2023 supplemental 
risk evaluation.
    In response to SACC recommendations, EPA expanded on the 
methodology reviewed by the SACC to evaluate multiple years of release 
data and to consider the combined risks from multiple facilities 
releasing 1,4-dioxane to a single media (ambient air). The methods used 
to evaluate combined exposure and risks from multiple facilities 
releasing 1,4-dioxane have not previously been applied in the context 
of TSCA risk assessments. The multi-year analysis applies the ``pre-
screening'' methodology described in the SACC-reviewed draft Fenceline 
report with some modifications to focus the analysis on a single 
exposure scenario found to represent a higher-end exposure estimate. 
While the pre-screening methodology has been reviewed by SACC, neither 
the modification to the approach nor the results from applying the 
modified pre-screening methodology have been presented prior to this 
supplemental risk evaluation.
    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.
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.\1\ 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

[[Page 17569]]

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 used for one of the first 10 chemicals.
     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 releases 
when estimating exposure concentrations in surface water for a TSCA 
risk evaluation.
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 a specific facility's given waste stream in a 
landfill or surface impoundment (see EPA's ``Hazardous Waste Delisting 
Risk Assessment Software Version 4. Lenexa''). DRAS was specifically 
designed to address the Criteria for Listing Hazardous Waste. The 
supplemental 1,4-dioxane risk evaluation presents a novel application 
of this model and first application in a TSCA 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. A second model, EPA's Composite 
Model for Leachate Migration with Transformation Products (EPACMTP), 
was also utilized in the 1,4-dioxane assessment to characterize the 
potential impact that different landfill liners might have when 
accounting for increasing amounts of data in a Monte Carlo analysis. 
This model has also not been previously used in any TSCA risk 
evaluations.
     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 supplemental 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.

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

    EPA is planning to release the draft supplement mentioned above and 
all background documents, related supporting materials, and draft 
charge questions provided to the SACC in June 2023. At that time, EPA 
will publish a separate document in the Federal Register to announce 
the availability of and solicit public comment on the draft supplement 
and provide instructions for submitting written comments and 
registering to provide oral comments. These materials will also be 
available in the docket through https://www.regulations.gov (docket ID 
number EPA-HQ-OPPT-2022-0905) and through the SACC website. In 
addition, 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 and on the SACC website.

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

    The public virtual 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 in the summer of 2023.
    Authority: 15 U.S.C. 2625(o); 5 U.S.C. 10.

    Dated: March 20, 2023.
Michal Freedhoff,
Assistant Administrator, Office of Chemical Safety and Pollution 
Prevention.
[FR Doc. 2023-05982 Filed 3-22-23; 8:45 am]
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