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Notice2023-15846

1,4-Dioxane; Draft Revision to Toxic Substances Control Act (TSCA) Risk Determination; Notice of Availability and Request for Comment

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Published

July 26, 2023

Issuing agencies

Environmental Protection Agency

Abstract

The Environmental Protection Agency (EPA) is announcing the availability of and requesting public comment on a draft revision to the risk determination for 1,4-dioxane following a risk evaluation issued under TSCA. EPA published a risk evaluation for 1,4-dioxane in December 2020 and a draft supplement to the risk evaluation in July 2023. This draft revision to the 1,4-dioxane risk determination reflects policy changes announced in June 2021, to ensure the public is protected from unreasonable risks from chemicals in a way that is supported by science and the law, as well as information from the 2023 Draft Supplement to the risk evaluation. In this draft revision to the risk determination EPA has preliminarily determined that 1,4-dioxane, as a whole chemical substance, presents an unreasonable risk of injury to health when evaluated under its conditions of use. This draft risk determination considers the occupational and consumer exposures from the December 2020 Risk Evaluation, as well as the occupational, general population, and fenceline community exposures in the draft supplement to the risk evaluation, including exposures that result from conditions of use where 1,4-dioxane is present due to production as a byproduct and the risks from general population and fenceline communities' exposures to 1,4-dioxane released under the conditions of use to drinking water sourced from surface and ground water and ambient air. In addition, this revised risk determination does not reflect an assumption that all workers always appropriately wear personal protective equipment (PPE). EPA understands that there could be adequate occupational safety protections in place at certain workplace locations; however, not assuming use of PPE reflects EPA's recognition that unreasonable risk may exist for subpopulations of workers that may be highly exposed because they are not covered by Occupational Safety and Health Administration (OSHA) standards, or their employers are out of compliance with OSHA standards, or because many of OSHA's chemical- specific permissible exposure limits largely adopted in the 1970's are described by OSHA as being "outdated and inadequate for ensuring protection of worker health," or because EPA finds unreasonable risk for purposes of TSCA notwithstanding OSHA requirements. This revision, when final, would supersede the condition of use-specific no unreasonable risk determinations in the December 2020 1,4-dioxane risk evaluation (and withdraw the associated order) and would make a revised determination of unreasonable risk for 1,4-dioxane as a whole chemical substance.

Full Text

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<title>Federal Register, Volume 88 Issue 142 (Wednesday, July 26, 2023)</title>
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[Federal Register Volume 88, Number 142 (Wednesday, July 26, 2023)]
[Notices]
[Pages 48249-48259]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-15846]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OPPT-2016-0723; FRL-7918-02-OCSPP]

1,4-Dioxane; Draft Revision to Toxic Substances Control Act
(TSCA) Risk Determination; Notice of Availability and Request for
Comment

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: The Environmental Protection Agency (EPA) is announcing the
availability of and requesting public comment on a draft revision to
the risk determination for 1,4-dioxane following a risk evaluation
issued under TSCA. EPA published a risk evaluation for 1,4-dioxane in
December 2020 and a draft supplement to the risk evaluation in July
2023. This draft revision to the 1,4-dioxane risk determination
reflects policy changes announced in June 2021, to ensure the public is
protected from unreasonable risks from chemicals in a way that is
supported by science and the law, as well as information from the 2023
Draft Supplement to the risk evaluation. In this draft revision to the
risk determination EPA has preliminarily determined that 1,4-dioxane,
as a whole chemical substance, presents an unreasonable risk of injury
to health when evaluated under its conditions of use. This draft risk

[[Page 48250]]

determination considers the occupational and consumer exposures from
the December 2020 Risk Evaluation, as well as the occupational, general
population, and fenceline community exposures in the draft supplement
to the risk evaluation, including exposures that result from conditions
of use where 1,4-dioxane is present due to production as a byproduct
and the risks from general population and fenceline communities'
exposures to 1,4-dioxane released under the conditions of use to
drinking water sourced from surface and ground water and ambient air.
In addition, this revised risk determination does not reflect an
assumption that all workers always appropriately wear personal
protective equipment (PPE). EPA understands that there could be
adequate occupational safety protections in place at certain workplace
locations; however, not assuming use of PPE reflects EPA's recognition
that unreasonable risk may exist for subpopulations of workers that may
be highly exposed because they are not covered by Occupational Safety
and Health Administration (OSHA) standards, or their employers are out
of compliance with OSHA standards, or because many of OSHA's chemical-
specific permissible exposure limits largely adopted in the 1970's are
described by OSHA as being ``outdated and inadequate for ensuring
protection of worker health,'' or because EPA finds unreasonable risk
for purposes of TSCA notwithstanding OSHA requirements. This revision,
when final, would supersede the condition of use-specific no
unreasonable risk determinations in the December 2020 1,4-dioxane risk
evaluation (and withdraw the associated order) and would make a revised
determination of unreasonable risk for 1,4-dioxane as a whole chemical
substance.

DATES: Comments must be received on or before September 8, 2023.

ADDRESSES: Submit your comments, identified by docket identification
(ID) number EPA--EPA-HQ-OPPT-2016-0723, through <a href="https://www.regulations.gov">https://www.regulations.gov</a>. 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
visiting the docket, along with more information about dockets
generally, is available at <a href="https://www.epa.gov/dockets">https://www.epa.gov/dockets</a>.

FOR FURTHER INFORMATION CONTACT:
For technical information contact: Cindy Wheeler, Office of
Pollution Prevention and Toxics (7404M), Environmental Protection
Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460-0001; telephone
number: (202) 566-0484; email address: <a href="/cdn-cgi/l/email-protection#fd999492859c9398d3a9aebebcbdb8adbcd39a928b">[email&#160;protected]</a>.
For general information contact: The TSCA-Hotline, ABVI-Goodwill,
422 South Clinton Ave., Rochester, NY 14620; telephone number: (202)
554-1404; email address: <a href="/cdn-cgi/l/email-protection#73272030325e3b1c071f1a1d16331603125d141c05">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION:

I. Executive Summary

A. 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, use, disposal, and/or the assessment of risks
involving chemical substances and mixtures. You may be potentially
affected by this action if you manufacture (defined under TSCA to
include import), process (including recycling), distribute in commerce,
use, or dispose of 1,4-dioxane, including 1,4-dioxane in products and
including processes that produce 1,4-dioxane as a byproduct. Since
other entities may also be interested in this draft revision to the
risk determination, EPA has not attempted to describe all the specific
entities that may be affected by this action.

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

TSCA section 6, 15 U.S.C. 2605, requires EPA to conduct risk
evaluations 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
(PESS) identified as relevant to the risk evaluation by the
Administrator, under the conditions of use. 15 U.S.C. 2605(b)(4)(A).
TSCA sections 6(b)(4)(A) through (H) enumerate the deadlines and
minimum requirements applicable to this process, including provisions
that provide instruction on chemical substances that must undergo
evaluation, the minimum components of a TSCA risk evaluation, and the
timelines for public comment and completion of the risk evaluation.
TSCA also requires that EPA operate in a manner that is consistent with
the best available science, make decisions based on the weight of the
scientific evidence, and consider reasonably available information. 15
U.S.C. 2625(h), (i), and (k).
The statute identifies the minimum components for all chemical
substance risk evaluations. For each risk evaluation, EPA must publish
a document that outlines the scope of the risk evaluation to be
conducted, which includes the hazards, exposures, conditions of use,
and the potentially exposed or susceptible subpopulations that EPA
expects to consider. 15 U.S.C. 2605(b)(4)(D). The statute further
provides that each risk evaluation must also: (1) integrate and assess
available information on hazards and exposures for the conditions of
use of the chemical substance, including information that is relevant
to specific risks of injury to health or the environment and
information on relevant potentially exposed or susceptible
subpopulations; (2) describe whether aggregate or sentinel exposures
were considered and the basis for that consideration; (3) take into
account, where relevant, the likely duration, intensity, frequency, and
number of exposures under the conditions of use; and (4) describe the
weight of the scientific evidence for the identified hazards and
exposures. 15 U.S.C. 2605(b)(4)(F)(i) through (ii) and (iv) through
(v). Each risk evaluation must not consider costs or other non-risk
factors. 15 U.S.C. 2605(b)(4)(F)(iii).
EPA has inherent authority to reconsider previous decisions and to
revise, replace, or repeal a decision to the extent permitted by law
and supported by reasoned explanation. FCC v. Fox Television Stations,
Inc., 556 U.S. 502, 515 (2009); see also Motor Vehicle Mfrs. Ass'n v.
State Farm Mutual Auto. Ins. Co., 463 U.S. 29, 42 (1983). Pursuant to
such authority, EPA is reconsidering the risk determinations in the
December 2020 1,4-Dioxane Risk Evaluation and issuing a 2023 draft risk
determination that encompasses the information in the 2023 Draft
Supplement to the risk evaluation.

C. What action is EPA taking?

EPA is announcing the availability of and seeking public comment on
a 2023 draft revision to the risk determination for the 2020 1,4-
Dioxane Risk Evaluation under TSCA (Ref. 1). This includes revision to
the risk determination initially published in December 2020 (Ref. 2)
and addition of information from the 2023 Draft Supplement to the risk
evaluation (Ref. 3), which includes evaluation of additional conditions
of use of 1,4-dioxane and critical exposure pathways not included in
the 2020 1,4-Dioxane Risk Evaluation. EPA has announced the
availability of the 2023 Draft

[[Page 48251]]

Supplement to the risk evaluation in a separate Federal Register
notice, which also describes the requests for public comment and the
peer review process for the 2023 Draft Supplement (88 FR 43562, July
10, 2023) (FRL-10798-02-OCSPP).
EPA is seeking public comment on the draft revision to the risk
determination for the risk evaluation where the agency preliminarily
intends to determine that 1,4-dioxane, as a whole chemical, presents an
unreasonable risk of injury to health when evaluated under its
conditions of use. The Agency has preliminarily determined that the
risk determination for 1,4-dioxane is better characterized as a whole
chemical risk determination rather than condition-of-use-specific risk
determinations. Accordingly, EPA would revise and replace section 5 of
the 2020 Risk Evaluation for 1,4-dioxane where the findings of
unreasonable risk to health were previously made for the individual
conditions of use evaluated. EPA would also withdraw the order issued
previously for two conditions of use previously determined not to
present unreasonable risk. However, before finalization of the risk
determination, EPA is specifically seeking public comment on several
aspects of the 2023 draft unreasonable risk determination, including
EPA's finding that general population and fenceline community exposure
to 1,4-dioxane in drinking water contributes to the determination that
1,4-dioxane presents an unreasonable risk and whether the risks to the
general population and fenceline communities from drinking water
exposure can be attributed to specific conditions of use of 1,4-
dioxane. A more robust description of the request for comment is in
Unit II.D.
This proposed revision to the 2020 unreasonable risk determination
would be consistent with EPA's plans to revise specific aspects of the
first ten TSCA chemical risk evaluations in order to ensure that the
risk evaluations better align with TSCA's objective of protecting
health and the environment. EPA proposes that the 2023 draft revision
would include several changes. First, EPA would make an unreasonable
risk determination for 1,4-dioxane as a whole chemical substance,
rather than making unreasonable risk determinations separately on each
individual condition of use evaluated in the risk evaluation. EPA
proposes that this is the most appropriate approach to 1,4-dioxane
under the statute and implementing regulations, with more explanation
provided in Unit II.C.1. Second, EPA would remove the assumption that
workers always and appropriately wear PPE (see Unit II.C.) in making
the whole chemical risk determination for 1,4-dioxane. The impacts of
this change are described in detail in Unit II.C.2. Third, based on the
2023 Draft Supplement to the risk evaluation, several additional
conditions of use would also contribute to the unreasonable risk
determination due to worker inhalation and dermal risks; these are
described in more detail in Unit II.C.3. Fourth, EPA proposes to
include risks to the general population and fenceline communities from
drinking water sourced from surface water contaminated with 1,4-dioxane
that is discharged from industrial facilities (including where it is
produced as a byproduct) as contributing to the unreasonable risk from
1,4-dioxane and is seeking public comment on several issues. These
risks are described in more detail in Unit II.C.4 and a description of
the request for comment is in Unit II.D. The list of the conditions of
use evaluated for the 1,4-dioxane TSCA risk evaluation is in Table 6-1
of the draft revised unreasonable risk determination (Ref. 1) and in
Table D-1 of the 2023 Draft Supplement to the Risk Evaluation for 1,4-
Dioxane (Ref. 3)).

D. What should I consider as I prepare my comments for EPA?

1. Submitting CBI. Do not submit this information to EPA through
<a href="http://regulations.gov">regulations.gov</a> or email. Clearly mark the part or all of the
information that you claim to be CBI. For CBI 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 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 <a href="http://www.epa.gov/dockets/comments.html">http://www.epa.gov/dockets/comments.html</a>.

II. Background

A. What is 1,4-dioxane and what did EPA evaluate in 2020?

1,4-Dioxane is primarily used as a solvent in commercial and
industrial applications. It can also be produced as a byproduct of
several common manufacturing processes, including but not limited to
ethoxylation processes used in the production of surfactants used in
soaps and detergents and production of polyethylene terephthalate (PET)
plastics. 1,4-Dioxane produced as a byproduct may remain present in
consumer and commercial products, including soaps and detergents,
cleaning products, antifreeze, textile dyes, and paints/lacquers. 1,4-
Dioxane is released to the environment from industrial and commercial
releases and from consumer and commercial products that are washed down
the drain or disposed of in landfills. People may be exposed to 1,4-
dioxane through occupational exposure, consumer products, or contact
with water, land, or air where 1,4-dioxane has been released to the
environment. Health effects of 1,4-dioxane include risks of liver
toxicity, adverse effects in the olfactory epithelium, and cancer.
1,4-Dioxane is one of the first 10 chemical substances undergoing
the TSCA risk evaluation process under TSCA section 6(b). In 2019, EPA
released the draft 1,4-dioxane risk evaluation, which assessed 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 received public comment, was reviewed by the Science Advisory
Committee on Chemicals (SACC). The Agency considered the SACC feedback
and is not seeking additional review of that information at this time
as this information has not changed.
A 2020 supplement to the draft 1,4-dioxane risk evaluation assessed
an additional eight additional conditions of use of 1,4-dioxane present
in consumer products and general population exposure to 1,4-dioxane
from incidental contact with surface water. Both assessments were
incorporated into the 2020 Risk Evaluation, which was released in
December 2020.
The December 2020 Risk Evaluation assessed a total of 24 conditions
of use. In December 2020, EPA determined that 13 conditions of use
presented unreasonable risks due to exposure to workers or occupational
non-users, and that 11 conditions of use did not present an
unreasonable risk (of those 11, 3 were industrial/commercial uses, and
8 were consumer uses). EPA found that none of the conditions of use
present an unreasonable risk to the environment.

[[Page 48252]]

B. Why is EPA re-issuing the risk determination for the 2023 1,4-
dioxane risk evaluation conducted under TSCA?

In 2016, as directed by TSCA section 6(b)(2)(A), EPA chose the
first ten chemical substances to undergo risk evaluations under the
amended TSCA. These chemical substances are asbestos, 1-bromopropane,
carbon tetrachloride, C.I. Pigment Violet (PV 29), cyclic aliphatic
bromide cluster (HBCD), 1,4-dioxane, methylene chloride, n-
methylpyrrolidone (NMP), perchloroethylene (PCE), and trichloroethylene
(TCE).
From June 2020 to January 2021, EPA published risk evaluations on
the first ten chemical substances, including for 1,4-dioxane in
December 2020. The risk evaluations included individual unreasonable
risk determinations for each condition of use evaluated. EPA issued
determinations that particular conditions of use did not present an
unreasonable risk by order under TSCA section 6(i)(1).
In accordance with Executive Order 13990 (Ref. 4) and other
Administration priorities (Refs. 5, 6, and 7), EPA reviewed the risk
evaluations for the first ten chemical substances, including 1,4-
dioxane, to ensure that they meet the requirements of TSCA, including
conducting decision making in a manner that is consistent with the best
available science.
As a result of this review, EPA announced plans to revise specific
aspects of the first ten risk evaluations in order to ensure that the
risk evaluations appropriately identify unreasonable risks and thereby
help ensure the protection of human health and the environment (Ref.
8). EPA also announced plans, in response to public comments and peer
review, to supplement the 2020 Risk Evaluation for 1,4-Dioxane to
assess critical human exposure pathways not previously considered in
the 2020 Risk Evaluation, and to consider occupational exposures to
conditions of use where 1,4-dioxane is present due to production as a
byproduct. EPA has now developed the 2023 Draft Supplement to the risk
evaluation and has announced its availability and request for public
comment in a separate Federal Register notice, which also describes the
peer review process (88 FR 43562, July 10, 2023) (FRL-10798-02-OCSPP).
In the 2023 Draft Supplement, EPA assessed the risks from 8 industrial/
commercial uses of 1,4-dioxane as a byproduct, from processing 1,4-
dioxane as a byproduct, and from the general population exposures to
1,4-dioxane in ambient air and drinking water. This 2023 draft revised
risk determination is for 1,4-dioxane as a whole chemical--and thus
includes not only information from the 2023 Draft Supplement to the
1,4-dioxane risk evaluation but also proposes revisions to the 2020
risk determination based on the 2020 Risk Evaluation. EPA is releasing
this 2023 draft revised unreasonable risk determination separately from
the draft supplement to the risk evaluation but is aligning the comment
period for the two documents so that the final unreasonable risk
determination can be released concurrently with the final supplemental
risk evaluation.
This action pertains only to the risk determination for 1,4-
dioxane. While EPA has taken additional similar actions on other of the
first ten chemicals, EPA is taking a chemical-specific approach to
reviewing the risk evaluations and is incorporating new policy
direction in a surgical manner, while being mindful of the
Congressional direction on the need to complete risk evaluations and
move toward any associated risk management activities in accordance
with statutory deadlines.

C. What are EPA's considerations in the draft revised unreasonable risk
determination for 1,4-dioxane?

In this draft revised unreasonable risk determination for 1,4-
dioxane, EPA is reconsidering two key aspects of the risk
determinations for 1,4-dioxane published in December 2020, proposing
several additional changes and updates, and highlighting specific
requests for comment.
First, following a review of specific aspects of the December 2020
1,4-dioxane risk evaluation, EPA proposes that making an unreasonable
risk determination for 1,4-dioxane as a whole chemical substance,
rather than making unreasonable risk determinations separately on each
individual condition of use evaluated in the risk evaluation, is the
most appropriate approach to 1,4-dioxane under the statute and
implementing regulations. Second, EPA proposes that the risk
determination should be explicit that it does not rely on assumptions
regarding the use of personal protective equipment (PPE) in making the
unreasonable risk determination under TSCA section 6, even though some
facilities might be using PPE as one means to reduce workers'
exposures; rather, the use of PPE as a means of addressing unreasonable
risk will be considered during risk management, as appropriate. As a
result, EPA preliminarily identifies two additional conditions of use
from the 2020 Risk Evaluation as contributing to the determination that
1,4-dioxane presents unreasonable risk. Additionally, for some of the
conditions of use in the 2020 Risk Evaluation that were identified as
``presenting'' an unreasonable risk to workers due to cancer,
eliminating the PPE assumption means that acute and chronic non-cancer
effects from inhalation exposure now also contribute to the
unreasonable risk. Third, based on the 2023 supplement to the risk
evaluation, EPA proposes to identify several additional conditions of
use as contributing to the unreasonable risk determination due to
worker inhalation and dermal risks. Fourth, EPA proposes that the risks
to the general population and fenceline communities from exposures to
1,4-dioxane in drinking water sourced from surface water contaminated
with industrial discharges of 1,4-dioxane (including when it is
generated as a byproduct) contributes to the determination that 1,4-
dioxane presents an unreasonable risk, and is seeking public comment on
several issues related to this proposed determination, as described in
Unit II.D.
1. What is a whole chemical view of the unreasonable risk
determination for the 1,4-dioxane risk evaluation?
TSCA section 6 repeatedly refers to determining whether a chemical
substance presents unreasonable risk under its conditions of use.
Stakeholders have disagreed over whether a chemical substance should
receive: A single determination that is comprehensive for the chemical
substance after considering the conditions of use, referred to as a
whole-chemical determination; or multiple determinations, each of which
is specific to a condition of use, referred to as condition-of-use-
specific determinations.
The proposed risk evaluation procedural rule was premised on the
whole chemical approach to making an unreasonable risk determination
(Ref. 9). In that proposed rule, EPA acknowledged a lack of specificity
in statutory text that might lead to different views about whether the
statute compelled EPA's risk evaluations to address all conditions of
use of a chemical substance or whether EPA had discretion to evaluate
some subset of conditions of use (i.e., to scope out some
manufacturing, processing, distribution in commerce, use, or disposal
activities), but also stated that ``EPA believes the word `the' [in
TSCA section 6(b)(4)(A)] is best interpreted as calling for evaluation
that considers all conditions of use.'' (Ref. 9).
The proposed rule, however, was unambiguous on the point that an

[[Page 48253]]

unreasonable risk determination would be for the chemical substance as
a whole, even if based on a subset of uses. (See Ref. 9 at pgs. 7565-
66: ``TSCA section 6(b)(4)(A) specifies that a risk evaluation must
determine whether `a chemical substance' presents an unreasonable risk
of injury to health or the environment `under the conditions of use.'
The evaluation is on the chemical substance--not individual conditions
of use--and it must be based on `the conditions of use.' In this
context, EPA believes the word `the' is best interpreted as calling for
evaluation that considers all conditions of use.''). In the proposed
regulatory text, EPA proposed to determine whether the chemical
substance presents an unreasonable risk of injury to health or the
environment under the conditions of use (Ref. 9 at pg. 7480).
The final risk evaluation procedural rule stated (82 FR 33726, July
20, 2017) (FRL-9964-38) (Ref. 10): ``As part of the risk evaluation,
EPA will determine whether the chemical substance presents an
unreasonable risk of injury to health or the environment under each
condition of uses [sic] within the scope of the risk evaluation, either
in a single decision document or in multiple decision documents.'' (See
also 40 CFR 702.47). For the unreasonable risk determinations in the
first ten risk evaluations, EPA applied this provision by making
individual risk determinations for each condition of use evaluated in
each risk evaluation (i.e., the condition-of-use-specific approach to
risk determinations). That approach was based on one particular passage
in the preamble to the final risk evaluation procedural rule, which
stated that EPA will make individual risk determinations for all
conditions of use identified in the scope. (Ref. 10 at pg. 33744).
In contrast to this portion of the preamble of the final risk
evaluation procedural rule, the regulatory text itself and other
statements in the preamble reference a risk determination for the
chemical substance under its conditions of use, rather than separate
risk determinations for each of the conditions of use of a chemical
substance. In the key regulatory provision excerpted earlier from 40
CFR 702.47, the text explains that ``[a]s part of the risk evaluation,
EPA will determine whether the chemical substance presents an
unreasonable risk of injury to health or the environment under each
condition of uses [sic] within the scope of the risk evaluation, either
in a single decision document or in multiple decision documents'' (Ref.
10, emphasis added). Other language reiterates this perspective. For
example, 40 CFR 702.31(a) states that the purpose of the rule is to
establish the EPA process for conducting a risk evaluation to determine
whether a chemical substance presents an unreasonable risk of injury to
health or the environment as required under TSCA section 6(b)(4)(B).
Likewise, there are recurring references to whether the chemical
substance presents an unreasonable risk in 40 CFR 702.41(a). See, for
example, 40 CFR 702.41(a)(6), which explains that the extent to which
EPA will refine its evaluations for one or more condition of use in any
risk evaluation will vary as necessary to determine whether a chemical
substance presents an unreasonable risk. Notwithstanding the one
preambular statement about condition-of-use-specific risk
determinations, the preamble to the final rule also contains support
for a risk determination on the chemical substance as a whole. In
discussing the identification of the conditions of use of a chemical
substance, the preamble notes that this task inevitably involves the
exercise of discretion on EPA's part, and ``as EPA interprets the
statute, the Agency is to exercise that discretion consistent with the
objective of conducting a technically sound, manageable evaluation to
determine whether a chemical substance--not just individual uses or
activities--presents an unreasonable risk.'' (Ref. 9 at pg. 33729).
Therefore, notwithstanding EPA's choice to issue condition-of-use-
specific risk determinations to date, EPA interprets its risk
evaluation regulation to also allow the Agency to issue whole-chemical
risk determinations. Either approach is permissible under the
regulation. A panel of the Ninth Circuit Court of Appeals also
recognized the ambiguity of the regulation on this point. Safer
Chemicals v. EPA, 943 F.3d 397, 413 (9th Cir. 2019) (holding a
challenge about ``use-by-use risk evaluations [was] not justiciable
because it is not clear, due to the ambiguous text of the Risk
Evaluation Rule, whether the Agency will actually conduct risk
evaluations in the manner Petitioners fear'').
EPA plans to consider the appropriate approach for each chemical
substance risk evaluation on a case-by-case basis, taking into account
considerations relevant to the specific chemical substance in light of
the Agency's obligations under TSCA. The Agency expects that this case-
by-case approach will provide greater flexibility in the Agency's
ability to evaluate and manage unreasonable risk from individual
chemical substances. EPA believes this is a reasonable approach under
TSCA and the Agency's implementing regulations.
With regard to the specific circumstances of 1,4-dioxane, as
further explained in this notice, EPA proposes that a whole chemical
approach is appropriate for 1,4-dioxane in order to protect health and
the environment. The whole chemical approach is appropriate for 1,4-
dioxane because there are benchmark exceedances for multiple conditions
of use (spanning across most aspects of the chemical lifecycle--from
manufacturing (including import), processing, industrial and commercial
use, and disposal) for health of workers, occupational non-users, and
fenceline communities and the general population, and the understanding
that the health effects (specifically liver toxicity, olfactory
epithelium effects, and cancer) associated with 1,4-dioxane exposures
are irreversible. Because these chemical-specific properties cut across
the conditions of use within the scope of the risk evaluation, it is
appropriate for the Agency to make a determination for 1,4-dioxane that
the whole chemical presents an unreasonable risk.
As explained later in this document, the revisions to the
unreasonable risk determination (section 5 of the 2020 Risk Evaluation)
would be based on the existing risk characterization section of the
2020 Risk Evaluation (section 4 of the 2020 Risk Evaluation) and the
2023 Draft Supplement to the Risk Evaluation for 1,4-Dioxane. The
discussion of the issues presented in this Federal Register notice and
in the accompanying draft revision to the risk determination would
supersede any conflicting statements in the prior 2020 1,4-dioxane risk
evaluation and the response to comments document (Ref. 11). With
respect to the 1,4-dioxane risk evaluation, while EPA intends to change
the risk determination to a whole chemical approach without considering
the use of PPE, EPA is basing the 2023 draft unreasonable risk
determination on the underlying scientific analysis from the 2020 Risk
Evaluation and 2023 Draft Supplement to the Risk Evaluation. EPA does
not intend to amend, nor does a whole chemical approach require
amending, the underlying scientific analysis of the risk evaluation in
the risk characterization section of the 2020 Risk Evaluation. EPA also
notes the Correction of Dermal Acute and Chronic Non-Cancer Hazard
Values Used to Evaluate Risks from Occupational Exposures that
explained, while the corrections slightly alter occupational dermal
risk estimates, they do not appreciably impact the overall

[[Page 48254]]

risk conclusions (Ref. 12). Because updates are not necessary for the
2020 publication, EPA views the peer reviewed hazard and exposure
assessments and associated risk characterization as robust and
upholding the standards of best available science and weight of the
scientific evidence per TSCA sections 26(h) and (i).
EPA is announcing the availability of and seeking public comment on
the 2023 draft unreasonable risk determination for 1,4-dioxane,
including a description of the risks contributing to the unreasonable
risk determination under the conditions of use for the chemical
substance as a whole. For purposes of TSCA section 6(i), EPA is making
a draft risk determination on 1,4-dioxane as a whole chemical. Under
the proposed revised approach, the ``whole chemical'' risk
determination for 1,4-dioxane would supersede the no unreasonable risk
determinations (and withdraw the associated order) for 1,4-dioxane that
were premised on a condition-of-use-specific approach to determining
unreasonable risk. When finalized, EPA's revised unreasonable risk
determination would also contain an order withdrawing the TSCA section
6(i)(1) order in section 5.4.1 of the December 2020 1,4-Dioxane Risk
Evaluation.
2. What revision does EPA propose about the use of PPE for the 1,4-
dioxane risk evaluation?
In the risk evaluations for the first ten chemical substances, as
part of the unreasonable risk determination, EPA assumed for several
conditions of use that workers were provided and always used PPE in a
manner that achieves the stated assigned protection factor (APF) for
respiratory protection, or used impervious gloves for dermal
protection. In support of this assumption, EPA used reasonably
available information such as public comments indicating that some
employers, particularly in the industrial setting, provide PPE to their
employees and follow established worker protection standards (e.g.,
Occupational Safety and Health Administration (OSHA) requirements for
protection of workers).
For the December 2020 1,4-Dioxane Risk Evaluation, EPA assumed,
based on reasonably available information, that workers use PPE--
specifically respirators with an APF ranging from 10 to 50 and gloves
with PF 10 or 20--for 15 occupational conditions of use. However, in
the December 2020 Risk Evaluation, EPA determined that there is
unreasonable risk for 13 of those 15 occupational conditions of use
even with assumed PPE.
EPA is revising the assumption for 1,4-dioxane that workers always
or properly use PPE. However, this does not mean that EPA questions the
veracity of public comments which describe occupational safety
practices often followed by industry. EPA believes it is appropriate
when conducting risk evaluations under TSCA to evaluate the levels of
risk present in baseline scenarios where PPE is not assumed to be used
by workers. This approach of not assuming PPE use by workers considers
the risk to potentially exposed or susceptible subpopulations (workers
and occupational non-users) who may not be covered by OSHA standards,
such as self-employed individuals and public sector workers who are not
covered by a State Plan. It should be noted that, in some cases,
baseline conditions may reflect certain mitigation measures, such as
engineering controls, in instances where exposure estimates are based
on monitoring data at facilities that have engineering controls in
place.
In addition, EPA believes it is appropriate to evaluate the levels
of risk present in scenarios considering applicable OSHA requirements
(e.g., chemical-specific permissible exposure limits (PELs) and/or
chemical-specific PELs with additional substance-specific standards) as
well as scenarios considering industry or sector best practices for
industrial hygiene that are clearly articulated to the Agency.
Consistent with this approach, the December 2020 1,4-dioxane risk
evaluation (Ref. 2) characterized risk to workers both with and without
the use of PPE. By characterizing risks using scenarios that reflect
different levels of mitigation, EPA risk evaluations can help inform
potential risk management actions by providing information that could
be used during risk management to tailor risk mitigation appropriately
to address any unreasonable risk identified, or to ensure that
applicable OSHA requirements or industry or sector best practices that
address the unreasonable risk are required for all potentially exposed
or susceptible subpopulations (including self-employed individuals and
public sector workers who are not covered by an OSHA State Plan).
Similarly, for the occupational exposures assessed as part of the added
conditions of use in the 2023 Draft Supplement to the 1,4-Dioxane Risk
Evaluation, EPA characterizes risks to workers with and without the use
of PPE (Complete risk calculations and results for occupational
conditions of use from the 2020 Risk Evaluation and the 2023 Draft
Supplement are in the Draft Supplement to the Risk Evaluation for 1,4-
Dioxane--Supplemental Information File: Occupational Exposure and Risk
Estimates (Ref. 13)).
When undertaking unreasonable risk determinations as part of TSCA
risk evaluations, however, EPA does not believe it is appropriate to
assume as a general matter that an applicable OSHA requirement or
industry practices related to PPE use is consistently and always
properly applied. Mitigation scenarios included in the EPA risk
evaluation (e.g., scenarios considering use of various PPE) likely
represent what is happening already in some facilities. However, the
Agency cannot assume that all facilities have adopted these practices
for the purposes of making the TSCA risk determination (Ref. 14).
Therefore, EPA proposes to make a determination of unreasonable
risk for 1,4-dioxane from a baseline scenario that does not assume
compliance with OSHA standards, including any applicable exposure
limits or requirements for use of respiratory protection or other PPE.
Making unreasonable risk determinations based on the baseline scenario
should not be viewed as an indication that EPA believes there are no
occupational safety protections in place at any location, or that there
is widespread non-compliance with applicable OSHA standards. Rather, it
reflects EPA's recognition that unreasonable risk may exist for
subpopulations of workers that may be highly exposed because they are
not covered by OSHA standards, such as self-employed individuals and
public sector workers who are not covered by a State Plan, or because
their employer is out of compliance with OSHA standards, or because
many of OSHA's chemical-specific permissible exposure limits largely
adopted in the 1970's are described by OSHA as being ``outdated and
inadequate for ensuring protection of worker health,'' (Ref. 15) or
because EPA finds unreasonable risk for purposes of TSCA
notwithstanding OSHA requirements.
In accordance with this approach, EPA is proposing the draft
revision to the 1,4-dioxane risk determination without relying on
assumptions regarding the occupational use of PPE in making the
unreasonable risk determination under TSCA section 6; rather,
information on the use of PPE as a means of mitigating risk (including
information received from industry respondents about occupational
safety practices in use) would be considered during the risk management
phase as

[[Page 48255]]

appropriate. This would represent a change from the approach taken in
the 2020 Risk Evaluation for 1,4-dioxane and EPA invites comments on
this 2023 draft change to the 1,4-dioxane risk determination. As a
general matter, when undertaking risk management actions, EPA intends
to strive for consistency with applicable OSHA requirements and
industry best practices, including appropriate application of the
hierarchy of controls, when those measures would address an identified
unreasonable risk, including unreasonable risk to potentially exposed
or susceptible subpopulations. Consistent with TSCA section 9(d), EPA
will consult and coordinate TSCA activities with OSHA and other
relevant Federal agencies for the purpose of achieving the maximum
applicability of TSCA while avoiding the imposition of duplicative
requirements. Informed by the mitigation scenarios and information
gathered during the risk evaluation and risk management process, the
Agency might propose rules that require risk management practices that
may be already common practice in many or most facilities. Adopting
clear, comprehensive regulatory standards will foster compliance across
all facilities (ensuring a level playing field) and assure protections
for all affected workers, especially in cases where current OSHA
standards may not apply or be sufficient to address the unreasonable
risk.
Removing the assumption that workers always and appropriately wear
PPE in making the whole chemical risk determination for 1,4-dioxane
would mean that for the conditions of use evaluated in the 2020 Risk
Evaluation, two conditions of use in addition to the original 13
conditions of use would contribute to the unreasonable risk
determination for 1,4-dioxane; an additional route of exposure (i.e.,
inhalation) would also be identified as contributing to the
unreasonable risk to workers in five of those 13 conditions of use; and
additional risks for acute and chronic non-cancer effects from
inhalation exposures would also contribute to the unreasonable risk
determination from seven of those 13 conditions of use (where
previously those conditions of use were identified as presenting
unreasonable risk from inhalation exposures only from cancer). The
draft revision to the risk determination would clarify that EPA does
not rely on the assumed use of PPE when making the risk determination
for the whole substance. EPA is requesting comment on this potential
change.
3. What conditions of use is EPA adding to the 2023 draft revised
unreasonable risk determination?
1,4-Dioxane produced as a byproduct of manufacturing processes can
result in occupational exposures in industrial settings and may be
present in consumer and commercial products. It also may be released to
the environment through direct and indirect industrial and commercial
releases. While the 2020 Risk Evaluation considered risks to consumers
and bystanders from 1,4-dioxane present in consumer products due to its
production as a byproduct, it did not evaluate other exposures to 1,4-
dioxane produced as a byproduct. The 2023 Draft Supplement to the risk
evaluation considers occupational, fenceline community, and general
population exposures that result from conditions of use where 1,4-
dioxane is present, including as a result of production as a byproduct.
These exposures include 1,4-dioxane present in drinking water sourced
from surface water as a result of direct and indirect industrial
releases and down-the-drain releases of consumer and commercial
products; 1,4-dioxane present in drinking water sourced from
groundwater contaminated as a result of disposals; and 1,4-dioxane
released to air from industrial and commercial sources.
The following conditions of use are added to the 2023 Draft
Supplement:
<bullet> Processing as a byproduct (including polyethylene
terephthalate (PET) byproduct and ethoxylation process byproduct);
<bullet> Industrial/commercial use: Other uses: Hydraulic
fracturing;
<bullet> Industrial/commercial use: Arts, crafts, and hobby
materials: Textile dye;
<bullet> Industrial/commercial use: Automotive care products:
Antifreeze;
<bullet> Industrial/commercial use: Cleaning and furniture care
products: Surface cleaner;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Dish soap;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Dishwasher detergent;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Laundry detergent; and
<bullet> Industrial/commercial use: Paints and coatings: Paint and
floor lacquer;
For each of these conditions of use, EPA evaluated risks of non-
cancer and cancer effects due to acute or chronic inhalation or dermal
exposure. For the 2023 draft supplement, EPA relied on the physical and
chemical properties information, as well as lifecycle information,
environmental fate and transport information, and hazard identification
and dose-response analyses presented in the 2020 Risk Evaluation (Ref.
2).
4. Which exposure pathways are being added to EPA's 2023 revised
unreasonable risk determination?
The 2020-2021 risk evaluations for several of the first 10
chemicals, including 1,4-dioxane, excluded exposure pathways that were
or could be regulated under another EPA-administered statute. For 1,4-
dioxane, the air and drinking water exposure pathways were excluded
from the 2020 Risk Evaluation and were not assessed. The 2023 Draft
Supplement evaluates risks from general population and fenceline
community exposures to 1,4-dioxane released to surface and groundwater,
air, and land. The risks EPA evaluated to fenceline communities and the
general population (using reasonably available monitoring and modeling
data for inhalation, dermal, and ingestion exposures) include risks
from the conditions of use assessed in the 2020 Risk Evaluation as well
as the conditions of use assessed in the 2023 Draft Supplement,
including conditions of use where 1,4-dioxane is manufactured, or where
it is present due to production as a byproduct. These exposures to 1,4-
dioxane include releases to air and water from polyethylene
terephthalate (PET) plastic manufacturing, ethoxylation processes,
hydraulic fracturing operations, and use of a range of consumer and
commercial products.

D. What conclusions is EPA proposing to reach in the 2023 draft revised
unreasonable risk determination and on what is EPA seeking public
comment?

In the 2020 Risk Evaluation, EPA determined that 1,4-dioxane
presents an unreasonable risk to health under the following 13
conditions of use, based on risks to workers:
<bullet> Manufacturing (domestic manufacture);
<bullet> Manufacturing (import/repackaging);
<bullet> Processing: Repackaging;
<bullet> Processing: Recycling;
<bullet> Processing: Non-incorporative;
<bullet> Processing: Processing as a reactant;
<bullet> Industrial/commercial use: Intermediate;
<bullet> Industrial/commercial use: Processing aid;
<bullet> Industrial/commercial use: Laboratory chemicals;
<bullet> Industrial/commercial use: Adhesives and sealants;
<bullet> Industrial/commercial use: Printing and printing
compositions;
<bullet> Industrial/commercial use: Dry film lubricant; and

[[Page 48256]]

<bullet> Disposal.
Under the proposed whole chemical approach to the 1,4-dioxane risk
determination, those same conditions of use would continue to
contribute to the unreasonable risk from 1,4-dioxane. In addition, by
removing the assumption of PPE use in making the whole chemical risk
determination for 1,4-dioxane, two conditions of use (in addition to
the original 13 conditions of use in the 2020 Risk Evaluation found to
contribute to the unreasonable risk) would contribute to the
unreasonable risk:
<bullet> Industrial/commercial use: Functional fluids (open and
closed system): Metalworking fluid, cutting and tapping fluid,
polyalkylene glycol fluid; and
<bullet> Industrial/commercial use: Other uses: Spray polyurethane
foam.
Of the conditions of use that have been added in the 2023 Draft
Supplement, EPA has preliminarily determined that the following would
contribute to the unreasonable risk determination, based on risks to
workers:
<bullet> Processing as a byproduct (including polyethylene
terephthalate (PET) byproduct and ethoxylation process byproduct);
<bullet> Industrial/commercial use: Other uses: Hydraulic
fracturing;
<bullet> Industrial/commercial use: Arts, crafts, and hobby
materials: Textile dye;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Dish soap;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Dishwasher detergent; and
<bullet> Industrial/commercial use: Paints and coatings: Paint and
floor lacquer.
Based on the occupational risk estimates and EPA's confidence in
them, EPA finds that the worker exposure to 1,4-dioxane from all but
four occupational conditions of use (Ref. 1) contributes to the
unreasonable risk from 1,4-dioxane.
In the 2020 Risk Evaluation, EPA evaluated risks to consumers from
eight conditions of use and found that they did not present an
unreasonable risk to consumers or bystanders. In the 2023 draft revised
unreasonable risk determination, EPA does not propose to identify the
consumer conditions of use as contributing to the unreasonable risk
determination from 1,4-dioxane. However, EPA notes that the generation
of 1,4-dioxane as an ethoxylation process byproduct--i.e., the upstream
processing of many of these the consumer products--does contribute to
the unreasonable risk determination, due to worker risks of cancer and
non-cancer effects from inhalation and dermal exposures during those
processes and risk to the general population and fenceline communities
from exposures to drinking water sourced from surface water
contaminated with 1,4-dioxane discharged from industrial facilities.
Regarding ambient air exposures, EPA estimated risks from fenceline
community exposures to 1,4-dioxane released to air. Risks were
evaluated for air releases from industrial conditions of use, hydraulic
fracturing operations, and industrial and institutional laundry
facilities. EPA's modeling methodologies, risk estimates, and
confidence in those estimates is described in Section 5 of the draft
supplemental risk evaluation (Ref. 3). Standard cancer benchmarks used
by EPA and other regulatory agencies are an increased cancer risk above
benchmarks ranging from 1 in 1,000,000 to 1 in 10,000 (i.e.,
1x10-\6\ to 1x10-\4\) depending on the
subpopulation exposed. Based on the risk estimates for cancer, non-
cancer acute effects, and non-cancer chronic effects, the fact that the
risk estimates are within the applicable benchmark range, and EPA's
confidence in the risk estimates, EPA preliminarily finds that
fenceline community exposure to 1,4-dioxane in ambient air from
releases from industrial conditions of use, including hydraulic
fracturing, industrial laundry facilities, and institutional laundry
facilities does not contribute to EPA's unreasonable risk
determination. More details on EPA's preliminary determination
regarding fenceline communities' exposure to 1,4-dioxane in ambient air
is in the 2023 draft revised risk determination (Ref. 1).
Regarding drinking water exposures, in the 2023 Draft Supplement,
EPA evaluated oral exposures via ingestion of drinking water sourced
from surface water or groundwater contaminated with 1,4-dioxane from
facility-specific releases, down-the-drain releases of consumer and
commercial products that contain 1,4-dioxane as a byproduct, hydraulic
fracturing releases, and leaching from landfills. 1,4-Dioxane is not
readily removed through typical wastewater or drinking water treatment
processes. Sources of 1,4-dioxane in surface water include direct and
indirect industrial releases from COUs where 1,4-dioxane is
manufactured, processed, or used, industrial COUs where 1,4-dioxane is
present due to production as a byproduct (including PET manufacturing,
ethoxylation processes, and hydraulic fracturing operations), and down-
the-drain releases of 1,4-dioxane present in consumer and commercial
products. EPA considered risks from these sources individually and in
aggregate. The relative contribution from different sources varies
under different conditions and is likely to be driven by site-specific
factors including the amounts released from each source, flow rates of
receiving water bodies, and proximity of releases to drinking water
intakes. Drinking water exposure and risk estimates for surface water
are highly dependent on the amount of 1,4-dioxane released and the flow
of the receiving water body. Exposure and risk estimates are also
influenced by whether there is a drinking water intake downstream of a
release and the degree of dilution that occurs between the point of
release and the drinking water intake. Available surface water
monitoring datasets are not designed to reflect source water impacts of
direct and indirect releases into water bodies. Therefore, EPA
estimated concentrations using modeling for a range of specific release
scenarios. Similarly, for groundwater, EPA estimated cancer and non-
cancer risks for a range of general population and fenceline community
exposures to groundwater used as drinking water; sources of 1,4-dioxane
in groundwater may include leachate from landfills and disposal of
hydraulic fracturing waste.
Based on information in the 2023 Draft Supplement to the risk
evaluation, several conditions of use of 1,4-dioxane could result in
exposures to the general population and fenceline communities from 1,4-
dioxane in drinking water after it is discharged from facilities
engaging in one of several conditions of use. EPA also notes that many
of the conditions of use assessed in the 2023 Draft Supplement
contribute to more than one exposure pathway. For example, 1,4-dioxane
present as a byproduct of PET manufacturing may contribute to
occupational exposures during manufacturing as well as exposures to the
general population and fenceline communities through releases to water.
In addition, for many of the exposure pathways assessed, multiple
conditions of use contribute to 1,4-dioxane exposure. For example, many
conditions of use can contribute to general population and fenceline
communities' exposures to 1,4-dioxane in surface water, including
industrial releases from a range of conditions of use and down-the-
drain releases of consumer and commercial products.
EPA proposes to include the risks to the general population and
fenceline communities from drinking water sourced from surface water
contaminated with 1,4-dioxane that is discharged from industrial
facilities (including where it is produced as a

[[Page 48257]]

byproduct) as contributing to the unreasonable risk determination.
However, due to the uncertainties described in this Unit, in more
detail in section 6.2.4 of the 2023 draft revised unreasonable risk
determination, and throughout the 2023 Draft Supplement, EPA has
outlined several specific requests for comment regarding this draft
risk determination, in this Unit.
As described in the 2023 draft revised unreasonable risk
determination, EPA's proposed unreasonable risk determination for 1,4-
dioxane as a whole chemical is based on cancer and non-cancer risks to
workers from inhalation and dermal exposures, and cancer risks to the
general population and fenceline communities from exposures to 1,4-
dioxane in drinking water sourced from surface water contaminated by
industrial discharges of 1,4-dioxane (including when it is generated as
a byproduct). EPA proposes to identify the following conditions of use,
from both the 2020 Risk Evaluation and the 2023 Draft Supplement, as
contributing to the unreasonable risk from 1,4-dioxane:
<bullet> Manufacture (including domestic manufacture and import);
<bullet> Processing (including repackaging, recycling, non-
incorporative, as a reactant, and as a byproduct);
<bullet> Industrial/commercial use: Functional fluids (open and
closed system): Metalworking fluid, cutting and tapping fluid,
polyalkylene glycol fluid, hydraulic fluid;
<bullet> Industrial/commercial use: Intermediate;
<bullet> Industrial/commercial use: Processing aid;
<bullet> Industrial/commercial use: Laboratory chemicals;
<bullet> Industrial/commercial use: Adhesives and sealants;
<bullet> Industrial/commercial use: Other uses: Printing and
printing compositions;
<bullet> Industrial/commercial use: Other uses: Dry film lubricant;
<bullet> Industrial/commercial use: Other uses: Spray polyurethane
foam;
<bullet> Industrial/commercial use: Other uses: Hydraulic
fracturing;
<bullet> Industrial/commercial use: Arts, crafts, and hobby
materials: Textile dye;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Dish soap;
<bullet> Industrial/commercial use: Laundry and dishwashing
products: Dishwasher detergent;
<bullet> Industrial/commercial use: Paints and coatings: Paint and
floor lacquer; and
<bullet> Disposal.
Because the risk estimates for all processing COUs identified and
evaluated in the 2020 Risk Evaluation and the 2023 Draft Supplement
(including those where 1,4-dioxane is processed as a byproduct)
contribute to the unreasonable risk, EPA believes that it is
appropriate to conclude that any processing of 1,4-dioxane contributes
to the unreasonable risk. This would include circumstances described
but not necessarily individually quantified in the 2020 Risk Evaluation
or the 2023 Draft Supplement, such as when 1,4-dioxane is generated as
a byproduct during sulfonation, sulfation, and esterification
processes. EPA also emphasizes that this determination identifies any
manufacturing, processing, or disposal of 1,4-dioxane--including as a
byproduct--as contributing to the unreasonable risk if the 1,4-dioxane
contaminates surface water that is the source of drinking water.
EPA is seeking public comment for certain considerations for
determining unreasonable risk to the general population or fenceline
communities from 1,4-dioxane in drinking water. EPA notes that the
agency has preliminarily determined that the worker risks identified
provide sufficient basis for the determination that 1,4-dioxane as a
whole chemical presents unreasonable risk. Nonetheless, for the
purposes of transparency, clear public communication on unreasonable
risk, and to inform future risk management activities, EPA is seeking
comment on the following:
<bullet> Industrial discharges of 1,4-dioxane to surface water. EPA
is able to provide risk estimates for drinking water contaminated with
1,4-dioxane from surface water discharges from some facility-specific
releases of 1,4-dioxane, including from some facilities that
manufacture, process, or use 1,4-dioxane (including as a byproduct).
Several high-end risk estimates exceed the range of applicable
benchmarks for increased cancer risk (i.e., 1x10-\4\ to
1x10-\6\), and EPA has higher confidence in the facility-
specific risk estimates for discharges to surface water compared to
other drinking water risk estimates (i.e., groundwater, down-the-drain
releases from commercial and consumer products). In general, the
aggregate analysis for drinking water sourced from surface water
indicates that the high-end risk analysis may be driven primarily by
high-end industrial releases, under certain conditions. EPA has
preliminarily determined that exposures to surface water containing
1,4-dioxane from industrial discharges contribute to the unreasonable
risk.
EPA seeks comment on whether EPA's evaluation of facilities that
discharge 1,4-dioxane in processes that manufacture 1,4-dioxane or
generate 1,4-dioxane as a byproduct (e.g., PET manufacturing, and
ethoxylation processes), can reasonably be assumed to represent the
spectrum of facilities or sectors producing 1,4-dioxane as a byproduct
for the purposes of risk determination and, if necessary, any risk
management action.
Because multiple sources may contribute to 1,4-dioxane
concentrations in drinking water sourced from surface water in a single
location, EPA estimated aggregate general population exposures and
risks that could occur from combined contributions from multiple
sources. EPA seeks comment on whether an unreasonable risk
determination is supported in instances where EPA is unable to
attribute exposures to specific COUs as specific sources of risk, but
rather is able to attribute exposures to sources of the chemical
covering many COUs as an aggregate contributor to unreasonable risk.
<bullet> Down-the-drain releases of 1,4-dioxane from consumer and
commercial products. EPA evaluated the potential contribution of down-
the-drain releases of consumer and commercial products that contain
1,4-dioxane as a byproduct to drinking water exposure and risk. EPA's
drinking water exposure estimates correspond to surface water
concentrations estimated by probabilistic modeling of down-the-drain
releases under varying population sizes and stream flows. With some
combinations of factors, exposures to down-the-drain releases of 1,4-
dioxane in drinking water alone result in increased cancer risks within
EPA's benchmark range of 1x10-\6\ to 1x10-\4\ in
some instances. Assuming no dilution between the point of release and
the drinking water intake, the estimated risks range from
2.04x10-\11\ to 6.11x10-\5\ with the risks
increasing as population increases and stream flow decreases. Based on
the conservative analysis of no assumed dilution, confidence in risk
estimates, and consideration of uncertainties, EPA has preliminarily
determined that down-the-drain releases of 1,4-dioxane do not
contribute to the unreasonable risk determination.
EPA seeks comment regarding to what extent factors such as stream
flow and population size should be factored into the unreasonable risk
determination, or whether consideration of those factors is more
appropriate for the risk management stage.
EPA seeks comment on its draft determination that down-the-drain
releases of 1,4-dioxane do not contribute

[[Page 48258]]

to the unreasonable risk determination due to the uncertainties
identified in the risk characterization regarding consumer and
commercial products that contain 1,4-dioxane as a byproduct (i.e.,
soaps, dishwashing detergents, and laundry detergent).
<bullet> Groundwater and potential 1,4-dioxane exposure in drinking
water. EPA estimated risks from exposures that could occur if
groundwater containing 1,4-dioxane is used as a source of drinking
water. These risk estimates are not tied to known releases at specific
locations. Rather, the analysis defines the conditions under which 1,4-
dioxane disposal to landfills or from hydraulic fracturing operations
could result in varying levels of risk from groundwater concentrations
of 1,4-dioxane. EPA's drinking water exposure scenario relies on the
assumption that modeled groundwater concentrations reflect the actual
groundwater concentrations that occur at well locations. While the
modeling methodology is robust and the release information relied on as
model input data is supported by moderate evidence, no monitoring data
are available to confirm detection of 1,4-dioxane in groundwater,
specifically near hydraulic fracturing operations. EPA has
preliminarily determined that groundwater containing 1,4-dioxane does
not contribute to the unreasonable risk determination. EPA seeks
comment on its draft determination that groundwater exposures from 1,4-
dioxane do not contribute to the unreasonable risk determination due to
the uncertainties identified in the risk characterization regarding
releases of 1,4-dioxane from landfill leachate and hydraulic fracturing
operations.
<bullet> Determination of general population and fenceline
community risks. As described in the 2023 Draft Supplement (Ref. 3),
fenceline communities are members of the general population that are in
proximity to air-emitting facilities or a receiving waterbody, and who
therefore may be disproportionately exposed to a chemical undergoing
risk evaluation under TSCA section 6. For the air pathway, proximity
goes out to 10,000 meters from an air emitting source. For the water
pathway, proximity does not refer to a specific distance measured from
a receiving waterbody, but rather to those members of the general
population that may interact with the receiving waterbody and thus may
be exposed. EPA seeks comment, for the purposes of drinking water, on
what parameters EPA should consider in identifying whether exposures to
the general populations contribute to an unreasonable risk
determination. Specifically, EPA seeks comment on whether and how to
incorporate exposures to the general population from multiple sources
that cannot be attributed to COUs, is dependent on site-specific
circumstances, variable across the country, or dependent on stream
flow, population size, or population density. EPA also seeks comment on
whether other parameters should be considered, and, if so, how they
should be incorporated.
As noted in Unit II.C.1., EPA is also seeking comment on the draft
superseding unreasonable risk determination for 1,4-dioxane, including
a description of the risks that contribute to the unreasonable risk
determination under the conditions of use for the chemical substance as
a whole. Additionally, as noted in Unit II.C.2, EPA is also seeking
comment on EPA's 2023 draft revision to the 1,4-dioxane risk
determination without relying on assumptions regarding the occupational
use of PPE in making the unreasonable risk determination under TSCA
section 6.

III. Revision of the December 2020 Risk Evaluation

A. Why is EPA proposing to revise the risk determination for the 1,4-
dioxane risk evaluation?

EPA is proposing to revise the risk determination for the 1,4-
dioxane risk evaluation pursuant to TSCA section 6(b) and consistent
with Executive Order 13990, (``Protecting Public Health and the
Environment and Restoring Science to Tackle the Climate Crisis'') and
other Administration priorities (Refs. 4, 5, and 7). EPA is revising
specific aspects of the first ten TSCA existing chemical risk
evaluations in order to ensure that the risk evaluations better align
with TSCA's objective of protecting health and the environment.
For the 1,4-dioxane risk evaluation, this includes the draft
revisions: (1) making the risk determination in this instance based on
the whole chemical substance instead of by individual conditions of
use, (2) emphasizing that EPA does not rely on the assumed use of PPE
when making the risk determination and identifying which conditions of
use in the 2020 Risk Evaluation would contribute to the unreasonable
risk determination based on worker exposure without assuming use of
PPE, (3) identifying which of the additional conditions evaluated in
the 2023 Draft Supplement contribute to the unreasonable risk
determination based on worker exposure, and (4) proposing that the
risks to fenceline communities from exposure to 1,4-dioxane in drinking
water sourced from surface water contaminated by industrial discharges
of 1,4-dioxane (including when it is generated as a byproduct) and (5)
seeking public comment on several issues, as listed in Unit II.D.

B. What are the draft revisions?

EPA is releasing a draft revision of the risk determination for the
1,4-dioxane risk evaluation pursuant to TSCA section 6(b). Under the
revised determination, EPA proposes to conclude that 1,4-dioxane, as
evaluated in the risk evaluation as a whole, presents an unreasonable
risk of injury to health under its conditions of use. This revision
would replace the previous unreasonable risk determinations made for
1,4-dioxane by individual conditions of use, supersede the
determinations (and withdraw the associated order) of no unreasonable
risk for the conditions of use identified in the TSCA section 6(i)(1)
no unreasonable risk order, clarify the lack of reliance on assumed use
of PPE as part of the risk determination, and incorporate information
(including the addition of conditions of use and exposure pathways)
assessed in the 2023 Draft Supplement to the Risk Evaluation for 1,4-
Dioxane.
These draft revisions do not alter any of the underlying technical
or scientific information that informs the risk characterization in the
2020 Risk Evaluation, and as such the hazard, exposure, and risk
characterization sections in the 2020 Risk Evaluation are not changed
except to the extent that statements about PPE assumptions in the
executive summary and including sections 4.2.2.6 (Occupational Risk
Estimation for Cancer Effects), 4.6.2.1 (Summary of Risk for Workers
and ONUs), and section 5.1.1.3 (Determining Unreasonable Risk of Injury
to Health) of the 1,4-dioxane risk evaluation would be superseded and
the 2023 draft risk determination also reflects the 2023 supplemental
risk evaluation. The discussion of the issues in this notice and in the
accompanying draft revision to the risk determination would supersede
any conflicting statements in the prior executive summary, including
sections 4.2.2.6, 4.6.2.1, and section 5.1.1.3 from the 1,4-dioxane
risk evaluation and the response to comments document (Refs. 2 and 11).

C. Will the draft revised risk determination be peer reviewed?

The risk determination (section 5 in the December 2020 Risk
Evaluation) was not part of the scope of the peer review of the 1,4-
dioxane risk evaluation by the SACC. Thus, consistent with that

[[Page 48259]]

approach, EPA is not seeking peer review of the 2023 draft revised
unreasonable risk determination for the 1,4-dioxane risk evaluation.
EPA is, however, seeking peer review as well as public comment on the
2023 Draft Supplement to the 1,4-Dioxane Risk Evaluation, as described
in a separate Federal Register notice (88 FR 43562, July 10, 2023)
(FRL-10798-02-OCSPP). EPA will consider changes made to the risk
evaluation in response to peer review and public comment on that
supplement when developing the final risk determination.

D. What are the next steps for finalizing revisions to the risk
determination?

EPA will review and consider public comment received on the draft
revised risk determination for the 1,4-dioxane risk evaluation and will
review and consider public comment and peer review on the 2023 Draft
Supplement to the 1,4-Dioxane Risk Evaluation. After considering those
public comments, EPA will issue the revised final 1,4-dioxane risk
determination. If finalized as drafted, EPA would also issue a new
order to withdraw the TSCA section 6(i)(1) no unreasonable risk order
issued in Section 5.4.1 of the 2020 1,4-dioxane risk evaluation. This
final revised risk determination would supersede the December 2020 risk
determinations of no unreasonable risk. Consistent with the statutory
requirements of TSCA, EPA would initiate risk management for 1,4-
dioxane either by applying one or more of the requirements under TSCA
section 6(a) to the extent necessary so that 1,4-dioxane no longer
presents an unreasonable risk or determining pursuant to TSCA sections
9(a) and/or 9(b) that other Federal laws can eliminate or reduce to a
sufficient extent the unreasonable risk.

IV. 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 Draft Revised Unreasonable Risk Determination for 1,4-
Dioxane, July 2023.
2. EPA. Risk Evaluation for 1,4-Dioxane. December 2020. EPA Document
#EPA-740-R1-8007. <a href="https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0092">https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0092</a>.
3. EPA. Draft Supplemental Risk Evaluation for 1,4-Dioxane. July
2023. EPA Document #EPA-740-D-23-001. <a href="https://www.regulations.gov/document/EPA-HQ-OPPT-2022-0905-0027">https://www.regulations.gov/document/EPA-HQ-OPPT-2022-0905-0027</a>.
4. Executive Order 13990. Protecting Public Health and the
Environment and Restoring Science to Tackle the Climate Crisis.
Federal Register. 86 FR 7037, January 25, 2021.
5. Executive Order 13985. Advancing Racial Equity and Support for
Underserved Communities Through the Federal Government. Federal
Register. 86 FR 7009, January 25, 2021.
6. Executive Order 14008. Tackling the Climate Crisis at Home and
Abroad. Federal Register. 86 FR 7619, February 1, 2021.
7. Presidential Memorandum. Memorandum on Restoring Trust in
Government Through Scientific Integrity and Evidence-Based
Policymaking. Federal Register. 86 FR 8845, February 10, 2021.
8. EPA Press Release. EPA Announces Path Forward for TSCA Chemical
Risk Evaluations. June 2021. <a href="https://www.epa.gov/newsreleases/epa-announces-path-forward-tsca-chemical-risk-evaluations">https://www.epa.gov/newsreleases/epa-announces-path-forward-tsca-chemical-risk-evaluations</a>.
9. EPA. Proposed Rule; Procedures for Chemical Risk Evaluation Under
the Amended Toxic Substances Control Act. Federal Register. 82 FR
7562, January 19, 2017 (FRL-9957-75).
10. EPA. Final Rule; Procedures for Chemical Risk Evaluation Under
the Amended Toxic Substances Control Act. Federal Register. 82 FR
33726, July 20, 2017 (FRL-9964-38).
11. EPA. Summary of External Peer Review and Public Comments and
Disposition for 1,4-Dioxane. December 2020. <a href="https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0093">https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0093</a>.
12. EPA. Correction of Dermal Acute and Chronic Non-Cancer Hazard
Values Used to Evaluate Risks from Occupational Exposures in the
Final Risk Evaluation for 1,4-dioxane. June 26, 2023.
13. EPA. Draft Supplement to the Risk Evaluation for 1,4-Dioxane--
Supplemental Information File: Occupational Exposure and Risk
Estimates. July 2023.
14. Occupational Safety and Health Administration (OSHA). Top 10
Most Frequently Cited Standards for Fiscal Year 2021 (Oct. 1, 2020,
to Sept. 30, 2021). Accessed October 13, 2022. <a href="https://www.osha.gov/top10citedstandards">https://www.osha.gov/top10citedstandards</a>.
15. Occupational Safety and Health Administration. Permissible
Exposure Limits--Annotated Tables. Accessed June 13, 2022. <a href="https://www.osha.gov/annotated-pels">https://www.osha.gov/annotated-pels</a>.

Authority: 15 U.S.C. 2601 et seq.

Dated: July 21, 2023.
Michal Freedhoff,
Assistant Administrator, Office of Chemical Safety and Pollution
Prevention.
[FR Doc. 2023-15846 Filed 7-25-23; 8:45 am]
BILLING CODE 6560-50-P

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