What Environmental Consultants Need to Know
Since EPA designated PFOA and PFOS as hazardous substances under federal Superfund law in 2024, one major question has hung over the environmental industry: Would the rule survive a court challenge?
On August 18, 2026, the U.S. Court of Appeals for the D.C. Circuit delivered a decisive answer. In Chamber of Commerce of the United States of America, et al. v. EPA, a three-judge panel denied the consolidated industry petitions challenging EPA’s rule. The decision leaves intact the 2024 designation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as hazardous substances under CERCLA. For environmental due diligence professionals supporting commercial real estate transactions, this decisive ruling reinforces that PFOA and PFOS remain firmly within the federal CERCLA liability and due diligence framework. (It’s important to remember that the ruling does not designate every PFAS compound as a CERCLA hazardous substance, and substantial regulatory uncertainty remains around other federal PFAS and state-specific requirements.)
Background on the Case
After EPA’s 2024 final rule, seven industry associations petitioned the D.C. Circuit to vacate the designation of PFOA and PFOS as hazardous substances under CERCLA. The petitioners argued that EPA should have been required to demonstrate that “substantial danger” would result from a release, rather than relying on a possibility of such danger. Notably, the petitioners did not dispute EPA’s underlying determination that releases of PFOA and PFOS may pose a substantial risk to public health, welfare or the environment. However, Industry groups argued that EPA inadequately assessed the rule’s economic consequences, including potential cleanup costs, litigation exposure and impacts on small businesses. The court found that EPA adequately considered costs and scientific uncertainty.
PFOA and PFOS Under the CERCLA Liability Umbrella
The ruling preserves several important regulatory and liability consequences, including:
- Immediate release reporting. A release totaling one pound or more of PFOA or PFOS within a 24-hour period triggers immediate notification requirements.
- Federal response authority. Subject to CERCLA’s statutory and regulatory requirements, EPA can investigate releases, direct response actions and seek reimbursement of eligible cleanup costs from potentially responsible parties.
- Private-party claims. States and private parties may pursue qualifying cost-recovery or contribution claims under CERCLA, depending on the circumstances and the statutory basis for the claim.
- Broader ownership and operational exposure. CERCLA’s liability framework can reach current owners and operators, former owners or operators at the time of disposal, arrangers and certain transporters. Whether liability attaches depends on the facts, statutory elements and available defenses or landowner protections.
- Federal property transfers. Federal agencies transferring contaminated property generally must provide notice concerning the storage, release or disposal of PFOA or PFOS and address CERCLA’s applicable deed-covenant requirements.
Implications for Environmental Due Diligence
For environmental consultants performing Phase I and Phase II ESAs, the ruling reinforces the need for research into past uses that could point to PFOA or PFOS contamination and potentially trigger CERCLA liability.
The Federal All Appropriate Inquiries rule is intended to identify conditions indicative of releases or threatened releases of CERCLA hazardous substances. Because PFOA and PFOS continue to fall within that category, consultants conducting Phase I ESAs to satisfy AAI should evaluate credible evidence of their use, storage, disposal or release.
Elevated PFAS potential is associated with facilities that manufactured, formulated, stored, used or received PFAS-containing materials. High-risk property histories may include:
- Airports, military installations and fire-training areas where aqueous film-forming foam was stored or used
- Chemical manufacturing and formulation facilities
- Metal plating and finishing operations
- Textile, carpet, paper and packaging operations
- Landfills and waste-handling facilities
- Wastewater treatment and biosolids-management operations
- Sites that received fill, sludge or waste from potential PFAS sources
The presence of one of these uses does not establish that a release occurred, but it may warrant closer historical review and a site-specific evaluation of how PFAS may have been handled.
PFOA and PFOS can migrate through groundwater and surface water, making it critical for environmental professionals to review historical data on adjoining properties, giving consideration to factors like:
- Groundwater-flow direction
- Surface-water drainage
- Stormwater and wastewater pathways
- Historic fire-training or foam-use areas
- Waste-disposal and fill-placement practices
- Upgradient industrial or military sources
- The relationship between potential source areas and drinking-water receptors
A defensible assessment must look beyond the parcel boundary when the surrounding land-use history indicates a plausible migration pathway.
While this was a decision around federal CERCLA liability, PFAS investigation remains technically complex. State standards, reporting thresholds, sampling requirements and cleanup criteria vary, and many states regulate more PFAS compounds than the two covered by the CERCLA designation.
EPA’s 2024 enforcement policy states that the agency intends to focus on entities that significantly contributed to PFAS releases, including manufacturers, industrial users and federal facilities. It identifies categories for which EPA may exercise enforcement discretion based on equitable factors, including community water systems, publicly owned treatment works, municipal stormwater systems, publicly operated landfills, publicly owned airports, local fire departments and certain farms receiving biosolids. As before, enforcement discretion is not a statutory exemption and does not necessarily prevent private-party contribution claims or state enforcement. After the ruling, EPA has also pledged to pursue Congress for new statutory language to fully address those concerns.
The Bottom Line
The D.C. Circuit’s decision substantially reduces legal uncertainty surrounding the federal CERCLA status of PFOA and PFOS. What it doesn’t do, however, is resolve every question about PFAS liability, nor does it require cleanup at every site where the compounds are detected.
For environmental consultants, PFOA and PFOS should be treated as material due diligence considerations whenever property history, surrounding uses or potential migration pathways indicate a credible concern. Environmental professionals can help clients identify historical uses, distinguish plausible concerns from unsupported assumptions, define appropriate follow-up work and understand how PFAS findings may affect liability protections, financing and transaction strategy.
The regulatory landscape will continue to evolve across federal and state programs. But after this ruling, one point is considerably clearer: PFOA and PFOS are firmly embedded in the CERCLA framework, and environmental due diligence practices must reflect that reality.
FOR MORE INFORMATION
DC Court Opinion (August 18, 2026)
