A coalition of seventeen environmental organizations, led by Earthjustice, has asked EPA to deny a premanufacture notice (PMN) under the Toxic Substances Control Act (TSCA) for a fluorinated immersion-cooling fluid intended to cool data-center equipment.  The comments press three lines of attack: that the substance poses an unreasonable risk EPA must act on, that the substance’s asserted benefits for data centers are legally irrelevant to that judgment, and that the applicant redacted health and safety information it was required to disclose.

The comments, filed July 15, 2026, respond to EPA’s notice of receipt of the PMN.  The substance is 3-Hexene, 1,1,1,2,2,5,5,6,6,6-decafluoro-, (3E) (CASRN 1256353-26-0), also known as Opteon 2P50.  The PMN applicant’s identity was claimed as confidential business information (CBI).

The Risk the Comments Describe

The coalition’s core argument is that the fluid presents an unreasonable risk that TSCA section 5 obligates EPA to prevent.  It characterizes the substance as a PFAS and urges EPA to find unreasonable risk on that basis alone, citing concerns including persistence, mobility, bioaccumulation potential, and toxicity.  The substance’s status as a PFAS is contested: when chemical supplier Chemours launched the fluid in 2023, it stated that it does not consider the compound a PFAS, describing it as a hydrofluoroolefin (HFO) that degrades quickly in the atmosphere.  The coalition, on the other hand, characterizes HFOs as PFAS and argues that HFOs break down in the atmosphere into shorter-chain PFAS—principally perfluoropropanoic acid (PFPrA) and trifluoroacetic acid (TFA)—that are persistent, highly mobile in water, and difficult to remediate.  They also cite a recent European Chemicals Agency risk assessment committee’s June 2026 opinion—adopted by consensus, now before the European Commission—proposing that TFA be classified as toxic to reproduction.

The comments also argue that the limited information available on the substance raises additional concerns about its risks.  Available toxicity data, they say, come largely from rat studies that understate PFAS risk to humans, and a workplace exposure limit derived by a group the comments describe as industry-linked relied on assumptions it did not disclose.  They add that the fluid is acutely toxic to aquatic life and not readily biodegradable, and that a hyperscale data center could hold tens of thousands of liters of dielectric fluid, with routine evaporative losses and disposal creating recurring releases near workers, fenceline communities, and waters around data centers and disposal sites.

How EPA Must Conduct the Review

A second line of argument concerns EPA’s review process.  TSCA section 5 directs EPA to decide whether a new chemical presents an unreasonable risk “without consideration of costs or other nonrisk factors.” EPA announced in September 2025 that it would prioritize review of new chemicals intended for data-center projects, inviting manufacturers to seek that treatment under Executive Order 14318.  The applicant filed a request for priority review premised on an urgent national need for AI infrastructure, which the coalition contends is irrelevant to the risk determination.  Priority review, they argue, affects when EPA takes up a submission, not the standard it must apply.

Two related arguments target how EPA models exposure.  The comments say EPA cannot assume workers will wear protective equipment, because under the occupational hierarchy of controls such equipment is a last line of defense and, in any event, accounting for its use would violate TSCA by conflating risk evaluation with risk management.  They also argue that EPA must weigh aggregate exposures from many facilities and other reasonably foreseen uses in its analysis.  As an example, the comments claim that the substance is marketed for other cooling applications, including use in electric-vehicle batteries.

The Confidentiality Dispute

The comments separately challenge the applicant’s CBI redactions.  They contend that TSCA generally bars confidentiality claims over health and safety information, yet the filing withheld entire toxicity-profile slides, the toxicological section of the safety data sheet, the applicant’s occupational exposure assessment, and its list of prior substantial risk notices under TSCA Section 8(e).  Other redactions concern information available on Chemours’ website, the coalition argues.

These arguments coincide with litigation brought by Earthjustice-represented environmental groups, which contends that EPA systemically fails to disclose information in PMNs claimed as CBI when the covered information does not facially qualify as confidential.

The comment period for the notice of receipt of the PMN closed July 15, 2026.