Federal Register #EPA-HQ-OPP-2026-5908

NASA Requests EPA Exemption for Ortho-Phthalaldehyde Biocide Use in ISS Coolant System

NASA has requested an emergency exemption from the EPA to use ortho-phthalaldehyde (OPA) as a biocide in the International Space Station (ISS) coolant system. - Government Buyer: - Environmental Protection Agency (EPA) - National Aeronautics and Space Administration (NASA) - OEMs and Vendors: - Ortho-phthalaldehyde (OPA) manufacturer (specific OEM not named) - Products/Services Requested: - Ortho-phthalaldehyde (OPA, CAS No. 643-79-8) biocide - Incorporated into porous resin canisters - Used to treat 829 liters of coolant fluid - Maximum concentration: 350 mg/L - Total required: 290,150 mg - Unique/Notable Requirements: - OPA is a new, unregistered chemical with EPA - NASA asserts OPA is the most effective biocide for ISS coolant system - OPA must be compatible with system materials and safe for crew - Application involves inserting resin canisters into the coolant loop for 8 hours - EPA is soliciting public comment before granting exemption - Treatment must be replenished every 1-2 years due to OPA degradation

Description

The Environmental Protection Agency (EPA) announces a request from NASA for a specific exemption to use the pesticide ortho-phthalaldehyde (OPA) to treat the coolant fluid of the internal active thermal control system (IATCS) of the International Space Station (ISS). The purpose is to control aerobic/microaerophilic bacteria in the aqueous coolant. This chemical is new and not registered by EPA. EPA is soliciting public comments for 15 days before deciding on the exemption.

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