EPA Finalizes National Recommended Aquatic Life Criteria And Benchmarks For Select PFAS

New discharge limits may be coming for certain Clean Water Act ("CWA") National Pollutant Discharge Elimination System ("NPDES") permits. In late September, EPA finalized national recommended water quality criteria for two of the most-studied per- and polyfluoroalkyl substances ("PFAS")—perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) —as well as benchmarks for eight other PFAS compounds with insufficient data, providing further direction for states and tribes in developing water quality standards and discharge limits under the Clean Water Act ("CWA"). This effort is part of EPA's PFAS Strategic Roadmap, began in 2021, with EPA aiming to publish aquatic life criteria and then human health criteria to control PFAS discharges and impacts on local communities.

Finalized Criteria and Benchmarks

The PFOA and PFOS CWA Section 304(a)(1) criteria recommendations are intended to support implementation of EPA's "latest scientific knowledge regarding the effects of these PFAS on aquatic organisms, such as fish and aquatic insects" and acknowledge that concentrations of PFAS above identified criteria (or benchmark level) "may harm the growth and reproduction of aquatic organisms or kill them." These aquatic life criteria are expressed in two forms: (1) acute criteria to protect against mortality or effects that occur due to a short-term exposure to a chemical, and (2) chronic criteria to protect against long-term risk of mortality, growth and reproductive effects due to chemical exposure.

EPA set aquatic life acute benchmarks for PFOA and PFOS in saltwater, where EPA had limited data, at 7.0 mg/L and 0.55 mg/L, respectively, for one-hour average not to be exceeded more than once in three years on average.

As part of this effort, EPA also finalized separate acute freshwater benchmarks under CWA Section 304(a)(2) for eight data-limited PFAS, again where EPA did not have enough data to establish criteria, including:

• perfluorobutanoic acid (PFBA) – 5.3 mg/L
• perfluorohexanoic acid (PFHxA) – 4.8 mg/L
• perfluorononanoic acid (PFNA) – 0.65 mg/L
• perfluorodecanoic acid (PFDA) – 0.50 mg/L
• perfluorobutanesulfonic acid (PFBS) – 5.0 mg/L
• perfluorohexanesulfonic acid (PFHxS) – 0.21 mg/L
• hexadecafluoro-2-decenoic acid (8:2 FTUCA) – 0.037 mg/L
• pentadecafluorodecanoic acid (7:3 FTCA) – 0.012 mg/L

Each benchmark is set for a duration of one-hour average, not to be exceeded more than once in three years on average.

The aquatic life benchmarks are "informational values" that reflect limited, high-quality toxicity data and data gaps that exist for several aquatic organism families. The recommended criteria and benchmarks are not regulatory and are not self-implementing; states may choose to adopt these or other criteria based on scientifically defensible standards. Any such state standards are implemented as discharge limits for NPDES permits.

Differences Compared to Draft Criteria

EPA's finalized PFOS criteria are stricter than the draft criteria published in 2022. The 2022 draft water column acute freshwater criteria for PFOS were 3.0 mg/L and chronic exposure of 0.0084 mg/L. Again, the finalized guidance significantly tightened these levels, recommending criteria values of 0.071 mg/L for acute exposure and 0.00025 mg/L for chronic exposure, as documented in the table above.

For PFOA, EPA also lowered the acute limits compared to the draft criteria, while the PFOA chronic limits remained approximately the same. Specifically, the PFOA acute water column exposure value was significantly tightened from 59 mg/L to 3.00 mg/L. EPA only slightly adjusted the PFOA chronic water column exposure value from 0.094 mg/L to 0.10 mg/L.

Notable Public Comments

In finalizing the 2022 draft proposed criteria, EPA considered several public comments. In addition to the finalized guidelines recommending aquatic life criteria for PFAS, EPA has published responses to notable comments, including:

• Missing Minimum Data Requirements.
  • The Association of Clean Water Administrators ("ACWA") noted that EPA employed approaches in the 2022 draft proposal "that will be problematic" for some states interested in adopting the recommended criteria. Most significantly, ACWA recommended rereleasing the criteria as another draft if any changes were made (such as meeting minimum data requirements in conformity with the 1985 Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses). ACWA sought addition of insects as the "missing [minimum data requirement]." EPA responded by stating that the finalized criteria and benchmark documents "now contain recently published data, which fulfills the freshwater acute and chronic eight minimum data requirements (MDRs) for both PFOA and PFOS Aquatic Life Criteria."
• Draft Criteria Differed from Protective Values in Other Jurisdictions.
  • Commenters noted differences between EPA's 2022 draft PFOA and PFOS Aquatic Life Criteria magnitudes as compared to protective values from other jurisdictions. EPA stated that differences resulted from the "latest, high quality toxicity data."
• EPA Included Criteria for PFOA and PFOS Separately, but Did Not Include Precursors or Mixtures.
  • Commenters recommended that mixtures of PFAS, including mixtures of PFOA and PFOS, be addressed "as these compounds are commonly detected together in various monitoring data," or that the EPA should consider releasing criteria for PFAS as a class, rather than as individual criteria. Other public comments included the recommendation that "aquatic life criteria for individual PFAS should go beyond PFOA and PFOS." EPA responded, "most of the research regarding toxicity of PFAS has focused on single-chemical PFOA or PFOS exposures, with sparse toxicity data on other PFAS or mixtures in comparison. Therefore, there are currently only sufficient data to derive national freshwater recommended aquatic life criteria for these individual compounds."
• EPA Used Data from Non-North American Species to Derive Its Levels.
  • Commenters expressed concern with the use of non-North American species in the draft PFOA and PFOS criteria. Specifically, commenters asserted that "the practice of including non-North American species is inconsistent with the goal of the CWA to provide for the protection and propagation of fish, shellfish and wildlife through the restoration and maintenance of the chemical, physical, and biological integrity of the Nation's waters." Commenters further suggested that "the use of non-North American species is inconsistent with the Aquatic Life Criteria Guidelines or may preclude some states from adopting the criteria, as they have policies and laws stating they cannot adopt criteria using non-resident or non-North American species." EPA stated that it relied on both North American and non-North American species to "ensure that the fullest, high-quality dataset available was used to represent the thousands of untested aquatic taxa present in U.S. ecosystems to ensure CWA goals may be met," and many of the non-North American species were from the same genus as North American species, "indicating their expected genetic and phenotypic similarity, which is expected to reflect greater similarities in toxicological response."

Impacts and Next Steps

EPA's PFAS aquatic life criteria and benchmarks reflect the agency's latest scientific understanding to be used by states for related water quality standards and guidance. To date, several states are first focusing on initial investigation advisory levels and drinking water limits. A handful of states have or are developing groundwater, surface water and cleanup objectives. Many states will likely be working to translate EPA's final criteria and benchmark data into water quality standards and will likely rely on the criteria and benchmarks. The states likely to move first are those that have already adopted some form of water quality standards, policies or guidance, including the following:

• California's Region 2 Regional Water Quality Control Board has issued interim final Environmental Screening Levels for PFOS and PFOA for the San Francisco Bay region. Currently, California does not have statewide water quality standards for PFAS, though the state's Office of Environmental Health Hazard Assessment and State Water Quality Control Board have stated repeatedly that the state is reviewing the latest scientific data and will likely leverage EPA's final criteria and benchmarks for this effort.
• Colorado has adopted site-specific groundwater standards for PFOS and PFOA (combined) of 70 ng/L for areas in El Paso County near Peterson Air Force Base, which are based on EPA's 2016 Drinking Water Health Advisories. Colorado has also adopted Policy 20-1, which translates narrative water quality standards for PFAS into numeric values. The policy contains translation values of 70 ng/L (0.00007 mg/L) for PFOA and PFOS, and values of 700 and 400,000 ng/L for PFHxs and PFBS, respectively. The policy also includes guidance for evaluating the presence of "parent constituents" that could degrade into PFAS (like PFOA or PFOS). Policy 20-1 expires on July 31, 2025. In 2025, CDPHE will begin to "[e]valuate other state approaches to establishing PFAS standards and regulations" and "work to obtain resources for developing and implementing regulatory authorities." Colorado's draft 2024 PFAS Action Plan also states that efforts are currently underway to "[s]upport and implement EPA's efforts to regulate excessive PFAS in various media" and "use best available science to determine whether to pursue additional Colorado environmental protections."
• Minnesota has initiated several standards for drinking water and surface water. The state has a surface water quality standard of 0.025 µg/l for PFOA and 0.00005 µg/l for PFOS and applies site-specific standards to Class 2 surface waters of the state (water used for aquatic life and recreation, including aquatic consumption). The Minnesota Pollution Control Agency also applies site-specific chronic criteria for six PFAS in Miles 820 to 812 of the Mississippi River, including PFOA and PFOS, as well as mixtures containing two or more of the following substances: PFBA, PFBS and PFHxA.
• New Hampshire has completed site-specific PFAS testing as part of its 2019 Plan to Generate PFAS Surface Water Quality Standards, but lawmakers have not yet codified the recommendations in the plan. Like Minnesota, New Hampshire's plan acknowledges that PFAS mixtures can be harmful and may need to be limited individually and in combination.
• New York stands out as already having adopted acute and chronic PFOS aquatic life guidance values for both freshwater and saline water: 0.71 mg/l for acute freshwater; 0.16 mg/l for chronic freshwater; 0.190 mg/l for acute saline water; and 0.041 mg/l for chronic saline water. The freshwater values are set much higher than EPA's criteria and will likely be revisited by the state. The acute saline value, though, is lower than EPA's criteria and may be subject to heightened critique now by dischargers.

EPA is expected to publish criteria for human health, though the timing of this is uncertain. Ultimately, PFAS regulation will continue to expand, continue to become stricter, and dischargers need to continue to stay up to date on what the EPA, states and tribes are doing with regard to PFAS.

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