PFAS in 2024: How Did We Get Here and Where Are We Going?

Published On: June 11, 2024

Last year, August Mack provided articles and webinars describing the likely forthcoming regulations for chemicals commonly referred to as “PFAS” or “per-and polyfluoryoalkyl substances”.  Well that time has arrived.  In April 2024, the U.S. EPA issued “the first ever national, legally enforceable drinking water standard to protect communities from exposure to harmful PFAS.”   Shortly after this announcement, EPA followed up with finalizing a rule to designate two of the most common PFAS substances – PFOA (perflurooctanoic acid) and PFOS (perfluorooctane sulfonic acid) – as hazardous substances under the Comprehensive Environmental Response, Compensation and Recovery Act (CERCLA).   Both of these new rules have significant ramifications for municipalities, industry, regulatory agencies, and environmental evaluation and cleanups.  This article will provide some background information on PFAS, followed by a discussion of the new rules from U.S. EPA.

Background Information

PFAS are a class of compounds (several thousand) that contain a chain of carbon and fluorine in their structure.   PFAS have been used globally for over 60 years, and are still being used because of their many useful properties – they are chemically inert; resistant to thermal breakdown; resistant to grease, oils, and water; and can act as a surfactant.  As a result of these properties, various PFAS compounds have been used in industrial chemicals and processes, household goods and clothing, food packaging, and aqueous film-forming foam (or AFFF), which is used most significantly for firefighting activities.  The same properties that make PFAS highly useful also make it problematic in the environment. PFAS do not decompose readily, they bioaccumulate in organisms, they are ubiquitous, and studies have shown that some PFAS compounds can have significant toxicity.  As such, states and the federal government have been increasing their regulatory efforts over the last several years.

The U.S. EPA’s PFAS Action Plan (2019) and the updated PFAS Strategic Roadmap (2021) both contained two key items that the Agency was evaluating and developing:  1) enforceable standards for PFAS in drinking water, and 2) establishing PFAS as “hazardous substances” under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), otherwise known as “Superfund”.  It took a few years, but the U.S. EPA delivered on these two goals, as well as some other regulations.

Federal Drinking Water Regulations (Maximum Contaminant Levels)

On April 10, 2024, the U.S. EPA announced the final National Primary Drinking Water Regulation for six (6) PFAS compounds, including PFOA, PFOS, PFHxS, PFNA, HFPO-DA (GenX), and PFBS.  According to U.S. EPA, over 120,000 comments were received on the proposed rule, which were considered when determining the final rule.  The NPDWR established individual Maximum Contaminant Levels (MCLs) for 5 of the PFAS compounds, and includes a Hazard Index of 1.0 as an MCL for PFAS mixtures containing 2 or more of PFHxS, PFNA, HFPO-DA, and PFBS.   Refer to the table below.  The use of a combined Hazard Index (HI) was developed to ensure that there are no health risks from exposures to chemical mixes as a result of “dose additivity”.


PFAS Compound EPA’s MCL Goal Final MCL (enforceable levels)
PFOA (perflurooctanoic acid) Zero 4.0 parts per trillion (ppt, also expressed as ng/l).
PFOS (perfluorooctane sulfonic acid) Zero 4.0 ppt
PFHxS (perfluorohexane sulfonic acid) 10 ppt 10 ppt
PFNA (perfluorononanoic acid) 10 ppt 10 ppt
HFPO-DA (hexafluoropropylene oxide dimer acid  – commonly referred to as “GenX” Chemicals. 10 ppt 10 ppt
Mixtures containing two or more PFHxS, PFNA, HFPO-DA, and PFBS 1.0 (unitless)

Hazard Index

1.0 (unitless)

Hazard Index


The final rule is effective on June 25, 2024, and requires that public water systems:

  • Conduct initial monitoring for these PFAS compounds by 2027, and conduct ongoing compliance monitoring.
  • Share the PFAS levels in water with the public beginning in 2027.
  • Implement solutions to reduce concentrations of PFAS by 2029 (if concentrations are above MCLs).
  • Notify the public of any violation of the MCLs beginning in 2029.


CERCLA Hazard Substances

On April 19, 2024, the U.S. EPA designated PFOA and PFOS as CERCLA “hazardous substances”.   This rule requires facilities to report spills greater than one pound over a 24-hour period, and allows U.S. EPA (and states) to respond to releases or threats of releases of these compounds under their CERCLA authority.  Along with the rule, the U.S. EPA also published a memorandum titled “PFAS Enforcement Discretion and Settlement Policy Under CERCLA” to outline how the U.S. EPA intends to utilize its enforcement ability under CERCLA for PFAS.   According to U.S.  EPA, this rule is intended on “holding accountable those parties that have played a significant role in releasing or exacerbating the spread of PFAS into the environment.”  As such, it will focus on those who have manufactured PFAS, or used PFAS in the manufacturing process, and other industrial parties. The discretionary policy also states that EPA does not intend to pursue response actions/costs for the following entities:  Community water system, publicly owned treatment works, municipal separate storm sewer systems, publicly owned landfills, publicly owned airports and fire departments, and farms where biosolids were applied.

The impacts of a CERCLA hazardous substances designation for PFAS will likely be far-reaching.  Besides the additional reporting requirements, there are many concerns among the regulated community and other stakeholders, including the following:

  • There will likely be more sites proposed and/or identified on the CERCLA National Priorities List.
  • Potential for re-openers of previously closed CERCLA sites, including already re-developed sites.
  • Disruptions among active remediation sites (CERCLA, and others) that could require significant additional resources to address.
  • Litigation associated with cost-recovery or private party actions. Under CERCLA, even parties that had a minimal contribution to PFOA or PFOS contamination could be subject to pay for the costs of cleanup.
  • Since PFAS is ubiquitous and persistent in the environment, it is possible that it could be identified as a “recognized environmental conditions” (RECs) during “all appropriate inquiry” Phase I Environmental Site Assessments conducted as part of a property transactions. This will likely have some impact on property transactions and potential Brownfield reuse.

This new rule is effective July 8, 2024.  August Mack will continue to stay abreast of the rapidly developing PFAS rulemaking efforts.

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