1,4-Dioxane; Draft Revision to Toxic Substances Control Act (TSCA) Risk Determination; Notice of Availability and Request for Comment, 48249-48259 [2023-15846]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 88, Number 142 (Wednesday, July 26, 2023)]
[Notices]
[Pages 48249-48259]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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 https://www.regulations.gov. Follow the online instructions for submitting 
comments. Do not submit electronically any information you consider to 
be Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Additional instructions on 
visiting the docket, along with more information about dockets 
generally, is available at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: 
    For technical information 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: [email protected].
    For general information contact: The TSCA-Hotline, ABVI-Goodwill, 
422 South Clinton Ave., Rochester, NY 14620; telephone number: (202) 
554-1404; email address: [email protected].

SUPPLEMENTARY INFORMATION:

I. Executive Summary

A. Does this action apply to me?

    This action is directed to the public in general. 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 
regulations.gov 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 https://www.epa.gov/dockets/comments.html.

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:
     Processing as a byproduct (including polyethylene 
terephthalate (PET) byproduct and ethoxylation process byproduct);
     Industrial/commercial use: Other uses: Hydraulic 
fracturing;
     Industrial/commercial use: Arts, crafts, and hobby 
materials: Textile dye;
     Industrial/commercial use: Automotive care products: 
Antifreeze;
     Industrial/commercial use: Cleaning and furniture care 
products: Surface cleaner;
     Industrial/commercial use: Laundry and dishwashing 
products: Dish soap;
     Industrial/commercial use: Laundry and dishwashing 
products: Dishwasher detergent;
     Industrial/commercial use: Laundry and dishwashing 
products: Laundry detergent; and
     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:
     Manufacturing (domestic manufacture);
     Manufacturing (import/repackaging);
     Processing: Repackaging;
     Processing: Recycling;
     Processing: Non-incorporative;
     Processing: Processing as a reactant;
     Industrial/commercial use: Intermediate;
     Industrial/commercial use: Processing aid;
     Industrial/commercial use: Laboratory chemicals;
     Industrial/commercial use: Adhesives and sealants;
     Industrial/commercial use: Printing and printing 
compositions;
     Industrial/commercial use: Dry film lubricant; and

[[Page 48256]]

     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:
     Industrial/commercial use: Functional fluids (open and 
closed system): Metalworking fluid, cutting and tapping fluid, 
polyalkylene glycol fluid; and
     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:
     Processing as a byproduct (including polyethylene 
terephthalate (PET) byproduct and ethoxylation process byproduct);
     Industrial/commercial use: Other uses: Hydraulic 
fracturing;
     Industrial/commercial use: Arts, crafts, and hobby 
materials: Textile dye;
     Industrial/commercial use: Laundry and dishwashing 
products: Dish soap;
     Industrial/commercial use: Laundry and dishwashing 
products: Dishwasher detergent; and
     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:
     Manufacture (including domestic manufacture and import);
     Processing (including repackaging, recycling, non-
incorporative, as a reactant, and as a byproduct);
     Industrial/commercial use: Functional fluids (open and 
closed system): Metalworking fluid, cutting and tapping fluid, 
polyalkylene glycol fluid, hydraulic fluid;
     Industrial/commercial use: Intermediate;
     Industrial/commercial use: Processing aid;
     Industrial/commercial use: Laboratory chemicals;
     Industrial/commercial use: Adhesives and sealants;
     Industrial/commercial use: Other uses: Printing and 
printing compositions;
     Industrial/commercial use: Other uses: Dry film lubricant;
     Industrial/commercial use: Other uses: Spray polyurethane 
foam;
     Industrial/commercial use: Other uses: Hydraulic 
fracturing;
     Industrial/commercial use: Arts, crafts, and hobby 
materials: Textile dye;
     Industrial/commercial use: Laundry and dishwashing 
products: Dish soap;
     Industrial/commercial use: Laundry and dishwashing 
products: Dishwasher detergent;
     Industrial/commercial use: Paints and coatings: Paint and 
floor lacquer; and
     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:
     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.
     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).
     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.
     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. https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0092.
3. EPA. Draft Supplemental Risk Evaluation for 1,4-Dioxane. July 
2023. EPA Document #EPA-740-D-23-001. https://www.regulations.gov/document/EPA-HQ-OPPT-2022-0905-0027.
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. https://www.epa.gov/newsreleases/epa-announces-path-forward-tsca-chemical-risk-evaluations.
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. https://www.regulations.gov/document/EPA-HQ-OPPT-2019-0238-0093.
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. https://www.osha.gov/top10citedstandards.
15. Occupational Safety and Health Administration. Permissible 
Exposure Limits--Annotated Tables. Accessed June 13, 2022. https://www.osha.gov/annotated-pels.

    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]
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