Law Clerk Klara A. Henry assisted in the drafting of this blog post.

On April 10, 2024, the EPA issued a highly anticipated final rule establishing legally enforceable limits for five types of PFAS (per- and polyfluoroalkyl substances, often called “forever chemicals”). The rule sets individual limits for these five forms of PFAS, as well as limits on two or more of the substances mixed together. The larger class of PFAS substances consists of almost 15,000 synthetic chemicals, many of which have been in use for decades. The five forms regulated in the EPA’s final rule are some of the most common forms in the United States. The enforceable Maximum Contaminant Levels (MCLs) for two types of PFAS—PFOA and PFOS—have been set at 4 parts per trillion, while MCLs for the three other types (PFHxS, PFNA, and HFPO-DA, also called “GenX chemicals”) have been set at 10 parts per trillion. The EPA also set non-enforceable Maximum Contaminant Level Goals, a health-based level, at zero for PFOA and PFOS, and at 10 parts per trillion for each of the other four regulated forms.

“Forever chemicals” have been on the Biden-Harris and EPA’s agenda for some time. Elevated levels of PFAS exposure has been linked to several types of cancer, and the CDC has estimated that over 97% of the US population has PFAS in their blood and tissue, whether through drinking water contamination, residue from food, or from ubiquitous consumer products like water-resistant clothing, outdoor furniture, and nonstick cookware.

The final rule differs in some major respects from the agency’s February 2024 proposed rule, in response to which the EPA received a whopping 120,000 public comments. Changes between the proposed and final rules include a deadline extension for public water systems to meet the new MCLs (increased from three to five years), more flexibility in monitoring schedules, and individual MCLs for the “GenX chemicals.”

As part of a “whole government approach,” this final rule complements other measures to reduce PFAS pollution under the Biden administration—the EPA announced nearly $1 billion in funding to help states and territories test and treat water to comply with the new standards. President Biden has also authorized a $9 billion investment through the Bipartisan Infrastructure Law, intended to support communities in addressing the broader concerns of emerging contaminants (of which PFAS is one). Another $12 billion in funding is available for general improvements in drinking water systems.

The EPA estimates that the new rule will reduce PFAS exposure for approximately 100 million people—the agency has estimated that up to 10% of the 66,000 public drinking water systems that will be affected by the final rule will need to make infrastructure changes in order to comply with the new standard, and will have three years in order to complete the first step: monitoring. Where PFAS exceeds the new standards, water systems must implement reduction solutions within five years. Though “forever chemicals” have earned their nickname due to the difficulty in removing them from soil, groundwater, and surface water, municipalities required to improve their systems in order to comply with the new rule may look towards several existing technologies that reduce PFAS concentration. These include granular activated carbon filters, reverse osmosis, and ion exchange systems. The new rule does not require implementation of any specific technology—systems will have flexibility in choosing which method or method combination they deem best for their community’s needs.

Wisconsin’s Department of Natural Resources commented on the final rule shortly after its publication, with the Director of DNR’s Bureau of Drinking Water and Groundwater assuring Wisconsinites that the state’s public water systems are “well positioned” to comply with the EPA’s enforceable standards. Public water systems in the state began sampling for PFOA and PFOS in 2022, so Wisconsin has already made progress on collecting data documenting instances of PFAS contamination. The DNR has promulgated a standard of 70 ppt for PFOA and PFOS in Wisconsin’s public drinking water. Regulated municipal water systems are required, however, to comply with the federal MCLs within the extended five-year timeframe. The DNR will also be undertaking a rulemaking to update its standards to be at least as stringent as the federal standards.


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