1,4-Dioxane; Supplement to the Risk Evaluation and Revised Unreasonable Risk Determination Under the Toxic Substances Control Act (TSCA); Notice of Availability, 89993-89995 [2024-26342]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 89, Number 220 (Thursday, November 14, 2024)]
[Notices]
[Pages 89993-89995]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-26342]


-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OPPT-2016-0723; FRL-7918-03-OCSPP]


1,4-Dioxane; Supplement to the Risk Evaluation and Revised 
Unreasonable Risk Determination Under the Toxic Substances Control Act 
(TSCA); Notice of Availability

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA or the Agency) is 
announcing the availability of the final supplement to the risk 
evaluation and revised unreasonable risk determination under the Toxic 
Substances Control Act (TSCA) for 1,4-dioxane. The purpose of risk 
evaluations under TSCA is to determine whether a chemical substance 
presents an unreasonable risk of injury to human health or the 
environment, without consideration of costs or non-risk factors, 
including unreasonable risk to potentially exposed or susceptible 
subpopulations identified as relevant to the risk evaluation by EPA, 
under the conditions of use. The Agency used the best available science 
to prepare this final supplement to the risk evaluation and has 
determined that 1,4-dioxane poses unreasonable risk to human health. 
Under TSCA, EPA must initiate risk management actions to address the 
unreasonable risk.

ADDRESSES: The docket for this action, identified by docket 
identification (ID) number EPA-HQ-OPPT-2016-0723, is available online 
at https://www.regulations.gov. Additional information about dockets 
generally, along with instructions for visiting the docket in-person, 
is available at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: 
    For technical information: Cindy Wheeler, Existing Chemicals Risk 
Management Division (7404M), Office of Pollution Prevention and Toxics, 
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, 
DC 20460-0001; telephone number: (202) 566-0484; email address: 
[email protected].
    For general information: 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 and may be of 
particular interest to those involved in the manufacture, processing, 
distribution, use, and disposal of 1,4-dioxane, related industry trade 
organizations, non-governmental organizations with an interest in human 
and environmental health, State and local governments, Tribal Nations, 
and/or those interested in the assessment of risks involving chemical 
substances and mixtures regulated under TSCA. As such, the Agency has 
not attempted to describe all the specific entities that this action 
might apply to. If you need help determining applicability, consult the 
technical contact listed under FOR FURTHER INFORMATION CONTACT.

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

    The Agency is conducting this risk evaluation under TSCA section 6, 
15 U.S.C. 2605, which requires that EPA conduct risk evaluations on 
chemical substances and identifies the minimum components EPA must 
include in all chemical substance risk evaluations. Each risk 
evaluation must be conducted consistent with the best available 
science, be based on the weight of

[[Page 89994]]

scientific evidence and consider reasonably available information. 15 
U.S.C. 2625(h), (i), and (k). See also the implementing procedural 
regulations at 40 CFR part 702.

C. What action is the Agency taking?

    EPA is announcing the availability of the final supplement to the 
1,4-dioxane risk evaluation and final revised unreasonable risk 
determination under TSCA. The purpose of risk evaluations under TSCA is 
to determine whether a chemical substance presents an unreasonable risk 
of injury to health or the environment, without consideration of costs 
or non-risk factors, including unreasonable risk to potentially exposed 
or susceptible subpopulations identified as relevant to the risk 
evaluation by EPA, under the conditions of use. EPA has used the best 
available science to prepare this final risk evaluation and has 
determined that 1,4-dioxane poses unreasonable risk to human health. 
Upon a determination of unreasonable risk, EPA must initiate risk 
management action as required pursuant to 15 U.S.C 2605(a) to address 
the unreasonable risk.

II. Background

    In 2016, EPA announced its designation of 1,4-dioxane for risk 
evaluation under TSCA (81 FR 91927, December 19, 2016 (FRL-9956-47)). 
1,4-Dioxane was one of the first 10 chemical substances undergoing the 
TSCA risk evaluation process after passage of the Frank R. Lautenberg 
Chemical Safety for the 21st Century Act, which amended TSCA. 1,4-
Dioxane is primarily used as a solvent in a variety of commercial and 
industrial applications such as the manufacture of other chemicals 
(e.g., adhesives, sealants) or as a processing aid or laboratory 
chemical. Although there are no direct consumer uses of 1,4-dioxane, it 
is present as a contaminant in commercial and consumer products and is 
produced as a byproduct through several manufacturing processes 
including ethoxylation, sulfonation, sulfation, and esterification.
    In the ``Draft Risk Evaluation for 1,4-Dioxane'' released in June 
2019 (hereafter ``2019 draft risk evaluation'') (84 FR 31315, July 1, 
2019 (FRL-9995-40)), EPA reviewed the exposures and hazards of 1,4-
dioxane for industrial and commercial uses and assessed risk from 
occupational exposures and surface water exposures to environmental 
organisms. That assessment, which included the physical and chemical 
properties, lifecycle information, environmental fate and transport 
information, and hazard identification and dose-response analysis, was 
peer reviewed by the Science Advisory Committee on Chemicals (SACC). In 
November 2020, EPA released the ``Draft Supplemental Analysis to the 
Draft Risk Evaluation for 1,4-Dioxane'' (hereafter ``2020 draft 
supplement'') that assessed conditions of use (COUs) of 1,4-dioxane as 
a contaminant in consumer products and general population exposure from 
incidental contact with surface water. The Agency determined that the 
2020 draft supplement did not warrant additional peer review as there 
was no novel analysis. The 2019 draft risk evaluation and 2020 draft 
supplement were both incorporated into the ``Final Risk Evaluation for 
1,4-Dioxane'' that was released in December 2020 (hereinafter ``2020 
final risk evaluaton'').
    In early 2021, and in response to presidential executive orders and 
policy changes, EPA reviewed the risk evaluations for the first 10 
chemical substances to ensure that the risk evaluations met the 
requirements of TSCA, including the requirement to use the best 
available science in decision-making. As a result of that review, the 
Agency announced plans to revise specific aspects of the first 10 risk 
evaluations to ensure that they appropriately identify unreasonable 
risks and thereby help to ensure the protection of human health and the 
environment. EPA determined an additional supplement to the 2020 final 
risk evaluation was needed to consider critical exposure pathways not 
previously assessed. Specifically, that additional supplement 
(hereinafter ``2023 draft supplement'') includes evaluation of 
additional conditions of use in which 1,4-dioxane is a byproduct in 
industrial processes and a contaminant in certain commercial products, 
and evaluates risks from general population exposures to 1,4-dioxane 
released to ambient surface water and groundwater, ambient air, and 
land. To evaluate these additional exposure pathways, the Agency used 
new methods and novel applications of existing methods. These new 
methods were subject to public comment and peer review as part of the 
2023 draft supplement (88 FR 48249, July 26, 2023 (FRL-7918-02-OCSPP)).
    Along with the 2023 draft supplement, EPA also published and took 
public comment on draft revisions to the unreasonable risk 
determination for 1,4-dioxane that considers the 2020 risk evaluation 
and the 2023 draft supplement. The 2023 draft revision to the 
unreasonable risk determination reflects policy changes announced in 
June 2021, and EPA preliminarily determined that 1,4-dioxane presents 
an unreasonable risk of injury to health when evaluated under its 
conditions of use.
    The final revised unreasonable risk determination that is being 
released with this announcement considers the 2020 risk evaluation and 
the final supplement that is also being released with this 
announcement. This final revised unreasonable risk determination 
supersedes the condition of use-specific no unreasonable risk 
determinations in the 2020 risk evaluation (and withdraws the 
associated order) and makes a final determination of unreasonable risk 
for 1,4-dioxane as discussed in Unit III.

III. Unreasonable Risk Determination

    EPA has determined that 1,4-dioxane presents an unreasonable risk 
of injury to human health under the conditions of use. The Agency has 
determined that the unreasonable risk to human health presented by 1,4-
dioxane is based on cancer and non-cancer risks (from liver toxicity 
and effects in the olfactory epithelium) to workers and occupational 
non-users (ONUs) from inhalation and dermal exposures, and cancer risks 
to the general population, including 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) and down-the-drain disposals of 
commercial and consumer products that are contaminated with 1,4-dioxane 
generated as a byproduct.
    Consistent with the statutory requirements of TSCA section 6(a), 
EPA will propose risk management regulatory actions to the extent 
necessary so that 1,4-dioxane no longer presents an unreasonable risk 
to health. The Agency expects to focus its risk management action on 
the conditions of use that significantly contribute to the unreasonable 
risk. However, it should be noted that under TSCA section 6(a), EPA is 
not limited to regulating the specific activities found to contribute 
significantly to unreasonable risk and may select from among a suite of 
risk management requirements in TSCA section 6(a) related to 
manufacture (including import), processing, distribution in commerce, 
commercial use, and disposal as part of its regulatory options to 
address the unreasonable risk. As a general example, EPA may regulate 
upstream activities (e.g., processing, distribution in commerce) to 
address downstream activities (e.g., consumer uses) contributing 
significantly to unreasonable risk, even if the upstream

[[Page 89995]]

activities do not contribute significantly to the unreasonable risk.
    In addition, as part of its evaluation, EPA has determined that 
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) and down-the-drain disposals of commercial 
and consumer products that are contaminated with 1,4-dioxane 
significantly contribute to the unreasonable risk from 1,4-dioxane. 
TSCA section 9(b) requires EPA to coordinate TSCA actions with actions 
taken under other Agency authorities. In coordinating regulatory action 
under TSCA with other offices at EPA, the Agency considered the 
authorities of the Safe Drinking Water Act (SDWA) and has determined 
that certain regulatory actions under the SDWA may also be appropriate. 
Therefore, as described in more detail in a memorandum included in this 
docket, and consistent with TSCA section 9(b)(1), OCSPP has 
memorialized this agreement for coordinated action on risks from 1,4-
dioxane contamination in drinking water through actions under both TSCA 
section 6(a) and, for Office of Water consideration of remaining risks 
and appropriate action, under SDWA.
    For more information about the TSCA risk evaluation process for 
existing chemicals, go to https://www.epa.gov/assessing-and-managing-chemicals-under-tsca.
    Authority: 15 U.S.C. 2601 et seq.

    Dated: November 7, 2024.
Michal Freedhoff,
Assistant Administrator, Office of Chemical Safety and Pollution 
Prevention.
[FR Doc. 2024-26342 Filed 11-13-24; 8:45 am]
BILLING CODE 6560-50-P