Environmental Protection Agency Docket EPA-HQ-OPP-2025-0758 Notice

2025-16549: Ortho-Phthalaldehyde; Receipt of Application for Emergency Exemption, Solicitation of Public Comment

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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.

The agency’s own summary, as published.

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