Notice2025-16549
Ortho-Phthalaldehyde; Receipt of Application for Emergency Exemption, Solicitation of Public Comment
Primary source
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Published
August 28, 2025
Issuing agencies
Environmental Protection Agency
Abstract
EPA is announcing a specific exemption request from the National Aeronautics and Space Administration (NASA) to use the pesticide ortho-phthalaldehyde (OPA, CAS No. 643-79-8) to treat the coolant fluid of the internal active thermal control system (IATCS) of the International Space Station (ISS) to control aerobic/ microaerophilic bacteria in the aqueous coolant. The applicant proposes the use of a new chemical which has not been registered by EPA. Therefore, in accordance with the Code of Federal Regulations, EPA is soliciting public comment before making the decision whether to grant the exemption.
Full Text
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<title>Federal Register, Volume 90 Issue 165 (Thursday, August 28, 2025)</title>
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[Federal Register Volume 90, Number 165 (Thursday, August 28, 2025)]
[Notices]
[Pages 42004-42005]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-16549]
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ENVIRONMENTAL PROTECTION AGENCY
[EPA-HQ-OPP-2025-0758; FRL-12948-01]
Ortho-Phthalaldehyde; Receipt of Application for Emergency
Exemption, Solicitation of Public Comment
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: EPA is announcing a specific exemption request from the
National Aeronautics and Space Administration (NASA) to use the
pesticide ortho-phthalaldehyde (OPA, CAS No. 643-79-8) to treat the
coolant fluid of the internal active thermal control system (IATCS) of
the International Space Station (ISS) to control aerobic/
microaerophilic bacteria in the aqueous coolant. The applicant proposes
the use of a new chemical which has not been registered by EPA.
Therefore, in accordance with the Code of Federal Regulations, EPA is
soliciting public comment before making the decision whether to grant
the exemption.
ADDRESSES: The docket for this action, identified by docket
identification (ID) number EPA-HQ-OPP-2025-0758, is available online at
<a href="https://www.regulations.gov">https://www.regulations.gov</a>. Additional information about dockets
generally, is available at <a href="https://www.epa.gov/dockets">https://www.epa.gov/dockets</a>.
FOR FURTHER INFORMATION CONTACT: Charles Smith, Director, Registration
Division (7505T), Office of Pesticide Programs, Environmental
Protection Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460-
0001; main telephone number: (202) 566-2875; email address:
<a href="/cdn-cgi/l/email-protection#42100604100c2d362b212731022732236c252d34"><span class="__cf_email__" data-cfemail="c89a8c8e9a86a7bca1abadbb88adb8a9e6afa7be">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
I. Executive Summary
A. Does this action apply to me?
You may be potentially affected by this action if you are a
pesticide manufacturer involved with the International Space Station.
The following North American Industrial Classification System (NAICS)
code is not intended to be exhaustive but rather provides a guide to
help readers determine whether this document applies to them. One
potentially affected entity may include Pesticide manufacturing (NAICS
code 32532). Other types of entities not listed could also be affected.
If you have any questions regarding the applicability of this
proposed action to a particular entity, consult the person listed under
FOR FURTHER INFORMATION CONTACT.
B. What is EPA's authority for taking this action?
Under section 18 of the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA) (7 U.S.C. 136p), at the discretion of the EPA
Administrator, a Federal or State agency may be exempted from any
provision of FIFRA if the EPA Administrator determines that emergency
conditions exist which require the exemption. EPA implementing
regulations are set forth in 40 CFR part 166.
C. What action is the Agency taking?
EPA is announcing receipt of a request submitted to EPA under FIFRA
section 18. This notice does not constitute a decision by EPA on the
application itself. The regulations governing FIFRA section 18 require
publication of a notice of receipt of an application for a specific
exemption
[[Page 42005]]
proposing use of a new chemical (i.e., an active ingredient) which has
not been registered by EPA.
II. Summary of the Request Received
NASA has requested that EPA issue a specific exemption for the use
of OPA in the coolant of the internal active thermal control system
(IATCS) of the ISS to control aerobic/microaerophilic bacteria in the
aqueous coolant. Information in accordance with 40 CFR part 166
(<a href="https://www.ecfr.gov/current/title-40/part-166">https://www.ecfr.gov/current/title-40/part-166</a>) was submitted as part
of this request.
As part of this request, the applicant asserts that it has
considered the registered biocide alternatives and concluded that OPA
is the most effective biocide that meets the requisite criteria
including: The need for safe, non-intrusive implementation and
operation in a functioning system; the ability to control existing
planktonic and biofilm-residing microorganisms; a negligible impact on
system wetted materials of construction; and a negligible reactivity
with existing coolant additives. Without the use of OPA, the ISS would
not have an adequate long-term solution for controlling these
microorganisms in the IATCS coolant.
The OPA is incorporated into a porous resin material contained in a
stainless-steel canister. The canister containing the OPA-incorporated
resin is inserted into a coolant system loop, using flexible hose and
quick disconnects, and is placed in line for 8 hours to deliver the OPA
into the fluid. As the coolant fluid flows through the cannister, the
OPA elutes from the resin material into the coolant fluid. The total
volume of the circulatory loops of the IATCS is 829 liters. The maximum
concentration would be 350 milligrams (mg) of OPA per liter of coolant
fluid. A total of 290, 150 mg would be needed for the entire system.
The OPA is incorporated into the resin at 210 mg of OPA per cm\3\
resin, resulting in potential total use of 1,382 cm\3\ of the OPA-
containing resin. The level of OPA in the coolant is monitored
periodically, and because OPA degrades over time, the concentration
decreases to a level that is no longer effective in about 1 to 2 years.
At this point, replenishment with new OPA-containing canisters is
required.
EPA has authorized similar emergency exemptions for this use since
2011. With the decision to extend the mission of the ISS to 2030, the
need for this use is expected to continue for the duration of the
program.
This notice provides an opportunity for public comment on the
application. The Agency will review and consider all comments received
during the comment in determining whether to issue the specific
exemption requested by NASA.
Authority: 7 U.S.C. 136 et seq.
Dated: August 26, 2025.
Charles Smith,
Director, Registration Division, Office of Pesticide Programs.
[FR Doc. 2025-16549 Filed 8-27-25; 8:45 am]
BILLING CODE 6560-50-P
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