On March 14, 2023, the US Environmental Protection Agency (EPA) proposed the first federally enforceable maximum contaminant levels (MCLs) for six per- and polyfluoroalkyl substances (PFAS) in drinking water. In a move that was expected following EPA’s 2022 publication of health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) that were essentially zero, EPA has proposed MCLs for those two PFAS at 4 parts per trillion (ppt), the lowest level that current technology can reliably detect. The proposed rule would also regulate perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA) (commonly known as GenX chemicals), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) through the use of a Hazard Index calculation to determine if the combined levels of these PFAS pose a potential risk to human health. EPA’s proposed MCLs will be published in the Federal Register and will be subject to public comment, which must be submitted within 60 days of the publication. In addition, EPA will hold webinars on March 16 and 29, 2023, and a public hearing on May 4, 2023, to collect comments. EPA indicated that it expects to finalize the regulation by the end of 2023. When finalized, the requirements will apply to public drinking water systems nationwide.

The MCLs proposed by EPA are not only as low as can be reliably detected, they are lower than those enacted by every state that has regulated PFAS in drinking water. As a result, if finalized, the proposed regulation will require public water systems to immediately monitor for these six chemicals and, if levels exceed the proposed regulatory standards: (1) notify the public within thirty (30) days; and (2) reduce the levels of these PFAS below the regulatory standards. It is anticipated that the vast majority, if not all, water systems in the United States will require costly remediation in order to meet the EPA’s proposed standards, potentially costing ratepayers and/or taxpayers billions of dollars. In fact, the state of New York estimates that remediation of PFAS in the state’s drinking water to a level of 4 ppt will cost $1.5 billion for start-up costs and $78 million annually. One can only imagine the cost of remediation in all fifty states.

Not only are the costs associated with the proposed regulation likely to be astronomical, the scientific basis for MCLs at levels this low has been called into question, thus raising the issue of whether the benefits outweigh the costs. In fact, the World Health Organization (WHO), based on its review of the relevant science, recently recommended a limit of 100 ppt for PFOA and PFOS in drinking water, a limit that is 25 times higher than that which EPA now proposes. Similarly, on February 11, 2023, Health Canada proposed guidelines for drinking water of 200 ppt for PFOA and 600 ppt for PFOS, 50 and 150 times higher than EPA proposes, respectively. As a result, the proposed MCLs are likely to be challenged. The American Chemistry Council (ACC), which previously challenged EPA’s PFAS health advisories,¹ issued the following statement concerning the proposed MCLs, previewing a likely challenge to the proposed regulation:

. . . we have serious concerns with the underlying science used to develop these proposed MCLs and have previously challenged the EPA based on the process used to develop that science. We are not alone in our concerns, as others have been on the record criticizing their development. And new peer-reviewed research also calls into question the basis for EPA’s overly conservative approach to assessing one of the health endpoints.

Importantly, the World Health Organization is also at odds with EPA on the health threshold for PFOA and PFOS. Furthermore, while we review the details, we would note that EPA has not yet evaluated two of the four chemistries included in the proposed “hazard index” MCL. We will be interested to see how EPA explains its rationale for combining substances affecting different health endpoints into a single index, in violation of its own guidance.

EPA’s proposed MCLs are likely the first in a series of legally enforceable standards affecting these widely used chemicals. All stakeholders should participate in EPA’s public sessions and public comment process in order to ensure not only that their perspectives are considered, but that the administrative record is preserved should they later wish to challenge the final rulemaking.

¹ In July 2022, the ACC filed a lawsuit challenging the EPA’s advisory levels, arguing that they reflect EPA’s failure to follow accepted practices for scientific integrity, and that the studies on which EPA relied fail to demonstrate causation or a minimum level of exposure that will result in adverse health effects. On January 23, 2023, the US Court of Appeals for the District of Columbia Circuit dismissed the suit for lack of standing.