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[Federal Register Volume 90, Number 3 (Monday, January 6, 2025)]
[Notices]
[Pages 638-640]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-31280]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OPPT-2018-0435]; FRL-8807-03-OCSPP]

Diisodecyl Phthalate (DIDP); Risk Evaluation Under the Toxic 
Substances Control Act (TSCA); Notice of Availability

AGENCY: Environmental Protection Agency (EPA).

[[Page 639]]

ACTION: Notice.

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SUMMARY: The Environmental Protection Agency (EPA or Agency) is 
announcing the availability of the final risk evaluation under the 
Toxic Substances Control Act (TSCA) for diisodecyl phthalate (DIDP). 
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 used the best available science to 
prepare this final risk evaluation and determined, based on the weight 
of scientific evidence, that DIDP 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-2018-0435, 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: Brianne Raccor, Existing Chemical Risk 
Management Division (7404M), Office of Pollution Prevention and Toxics, 
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, 
DC 20460-0001; telephone number: (202) 564-0303; 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 DIDP, 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 conducted 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 the 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 risk evaluation 
under TSCA for DIDP. 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 based on 
the weight of scientific evidence, determined that DIDP poses 
unreasonable risk to human health. Upon a determination of unreasonable 
risk, EPA must initiate risk management action as required pursuant to 
TSCA section 6(a), 15 U.S.C 2605(a), to address the unreasonable risk.

II. Background

A. What is DIDP?

    DIDP is a common chemical name for the category of chemical 
substances that includes the following substances: 1,2- 
benzenedicarboxylic acid, 1,2-diisodecyl ester (CASRN 26761-40-0) and 
1,2-benzenedicarboxylic acid, di-C9-11-branched alkyl esters, C10-rich 
(CASRN 68515-49-1). Both CASRNs contain mainly C10 dialkyl phthalate 
esters. DIDP is manufactured (including imported), processed, 
distributed, and disposed as part of industrial, commercial, and 
consumer conditions of use. DIDP is used primarily as a plasticizer to 
make flexible polyvinyl chloride (PVC). It is also used to make 
building and construction materials; automotive articles; and other 
commercial and consumer products including adhesives and sealants, 
paints and coatings, and electrical and electronic products. The 
production volume of DIDP has increased significantly over the past 
decade from between 100 and 250 million pounds in 2015 to between 100 
million and 1 billion pounds in 2019.

B. Risk Evaluation of DIDP

    In May 2019, EPA received a request to conduct a risk evaluation 
DIDP from ExxonMobil Chemical Company, Evonik Corporation, and Teknor 
Apex, through the American Chemistry Council's High Phthalates Panel 
(ACC HPP). In December 2019, EPA notified ACC HPP that the Agency had 
granted the manufacturer requested risk evaluation. See EPA-HQ-OPPT-
2018-0435 (Ref. 1). In November 2020, EPA released the draft scope of 
the DIDP risk evaluation (Ref. 2) and, after considering public 
comments, issued the final problem formulation in August 2021 (Ref. 3). 
On February 29, 2024, EPA released a draft risk evaluation for public 
comment and peer review by the Science Advisory Committee on Chemicals 
(SACC). (Ref. 4). The draft documents and public comments are in docket 
ID number EPA-HQ-OPPT-2024-0073. A non-technical summary is also 
available (Ref. 5). Given the shared peer review and chemical 
similarities with DINP, a shared set of responses to peer review and 
public comments will be available in January 2025 when the final 
Diisononyl Phthalate (DINP) risk evaluation is released (Ref. 6).

III. Unreasonable Risk Determination

    EPA has determined that DIDP presents an unreasonable risk of 
injury to human health under the conditions of use. EPA did not 
identify risk of injury to the environment that would contribute to the 
unreasonable risk determination for DIDP. EPA has determined that the 
unreasonable risk to human health presented by DIDP is due to non-
cancer effects (i.e., reduced offspring survival) in female workers of 
reproductive age from acute inhalation exposures and acute aggregated 
exposures. The unreasonable risk determination is based on the 
information within the risk evaluation, the appendices, and technical 
support documents of the risk evaluation in accordance with TSCA 
section 6(b). It is also based on TSCA's best available science (TSCA 
section 26(h)), weight of scientific evidence standards (TSCA section 
26(i)), and relevant implementing regulations in 40 CFR part 702, 
including, to the extent practicable, the amendments to the procedures 
for chemical risk evaluation

[[Page 640]]

under TSCA finalized in May 2024 (89 FR 37028; May 3, 2024).
    Between release of the draft risk evaluation and finalization of 
the DIDP risk evaluation, EPA updated the risk determination to find 
that six COUs contribute to unreasonable risk of DIDP based on new 
information identified by EPA, information provided by public 
commenters, and recommendations of the SACC. These changes stem from 
consideration of 1) multiple factors impacting occupational exposure 
during spray application, 2) applicability of developmental effects to 
average adult workers, and 3) identification of DIDP-containing 
products that could be spray applied. The COUs that EPA identified as 
presenting unreasonable risk were for acute exposure scenarios in which 
unprotected female workers of reproductive age were to spray adhesives 
and sealants; paints and coatings; lacquers, stains, varnishes, and 
floor finishes; or penetrants and inspection fluids that contain DIDP, 
because doing so could create high concentrations of DIDP in mist that 
an unprotected worker could inhale. The human health hazard that EPA 
identified as having the strongest evidence to support this risk 
evaluation is developmental toxicity, which means that laboratory 
animals dosed with DIDP had litters where more rodent offspring died 
than was the case with the litters of rodents that were not dosed with 
DIDP. As the most sensitive health effects of concern relate to 
exposure of the developing fetus during gestation, the population to 
which this risk determination is most relevant is female workers of 
reproductive age.
    Consistent with the statutory requirements of TSCA section 6(a), 
EPA will propose a risk management regulatory action to the extent 
necessary so that DIDP no longer presents an unreasonable risk. EPA 
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 drive unreasonable risk and 
may select from among a suite of risk management requirements in 
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., 
industrial and commercial uses) driving unreasonable risk, even if the 
upstream activities do not drive the unreasonable risk. Like the 
prioritization and risk evaluation processes, there is an opportunity 
for public comment on any proposed risk management actions.
    For more information about the TSCA risk evaluation process for 
existing chemicals, go to https://www.epa.gov/assessing-and-managing-chemicals-under-tsca.

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. Di-isodecyl Phthalate (DIDP); Manufacturer Request for Risk 
Evaluation Under the Toxic Substances Control Act (TSCA); Notice of 
Availability and Request for Comments. Federal Register. 84 FR 
42914, August 19, 2019 (FRL-9998-26).
2. EPA. Di-isodecyl Phthalate (DIDP); Draft Scope of the Risk 
Evaluation to be Conducted Under the Toxic Substances Control Act 
(TSCA); Notice of Availability and Request for Comments. Federal 
Register. 85 FR 76077, November 27, 2020 (FRL-10017-14).
3. EPA. Di-isodecyl Phthalate (DIDP); Final Scope of the Risk 
Evaluation To Be Conducted Under the Toxic Substances Control Act 
(TSCA); Notice of Availability. Federal Register. 86 FR 48695, 
August 31, 2021 (FRL-8807-01-OCSPP).
4. EPA. Di-isodecyl Phthalate (DIDP) and Di-isononyl Phthalate 
(DINP); Science Advisory Committee on Chemicals (SACC) Peer Review 
of Draft Documents; Notice of SACC Meeting; Availability; and 
Request for Comment. Federal Register. 89 FR 43847, May 20, 2024 
(FRL-11760-02-OCSPP).
5. EPA. Nontechnical Summary of the TSCA Risk Evaluation for 
Diisodecyl Phthalate (DIDP). December 2024. (EPA Document ID No. 
EPA-740-S-24-008).
6. EPA. Comment Summary and Responses for Diisodecyl Phthalate 
(DIDP) and Diisononyl Phthalate (DINP). December 2024.
    Authority: 15 U.S.C. 2601 et seq.

    Dated: December 20, 2024.
Michal Freedhoff,
Assistant Administrator, Office of Chemical Safety and Pollution 
Prevention.
[FR Doc. 2024-31280 Filed 1-3-25; 8:45 am]
BILLING CODE 6560-50-P
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