EPA Boosts Superfund PFAS Screening, Adds PFAS Chemicals to Lists of Risk-Based Values

May 23, 2022

The US Environmental Protection Agency announced on May 18 the addition of five per- and polyfluoroalkyl (PFAS) chemicals to its Regional Removal Management Levels and Regional Screening Levels. These additions signal the agency’s increasing efforts to investigate and address PFAS chemicals at sites of alleged contamination.

The additions at the federal level also provide further justification for states—many of which are forging ahead with PFAS investigations despite the lack of clear federal guidance and action—to address alleged PFAS contamination.

The five PFAS additions include

  • hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA, also referred to as GenX);
  • perfluorooctanesulfonic acid (PFOS);
  • perfluorooctanoic acid (PFOA);
  • perfluorononanoic acid (PFNA); and
  • perfluorohexanesulfonic acid (PFHxS).

With these additions, the Regional Screening Levels (RSLs) and Regional Removal Management Levels (RMLs) now include a total of six PFAS chemicals. The EPA added perfluorobutanesulfonic acid (PFBS) to the RMLs and RSLs in 2014 and updated the PFBS risk levels in 2021 when it released an updated toxicity assessment for that chemical. 

RMLs and RSLs are risk-based values that the EPA uses to determine whether removal action or further investigation is needed at a site to protect human health and nearby communities. RMLs and RSLs are not de facto cleanup standards. Rather, RMLs are generic levels used to define areas, contaminants, and conditions that may warrant a removal action under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), such as providing alternative drinking water or hot spot remediation. RSLs are conservative values used to screen sites by identifying contaminated media (i.e., air, water, or soil) requiring further study. Where contaminant concentrations fall below the levels in the RSLs, no further action or study is generally warranted.  

The EPA calculated levels for PFOA, PFOS, PFNA, and PFHxS using the most updated peer-reviewed information based on Minimal Risk Levels from the Agency for Toxic Substances and Disease Registry’s (ATSDR’s) 2021 toxicological profile. By relying on the controversially low levels recommended by the ATSDR for the new RMLs and RSLs, it appears as though the EPA has now embraced ATSDR’s profiles for PFAS. Accordingly, RSL calculations will now be based on reference doses that are 10 times more stringent for PFOS and seven times more stringent for PFOA than those used by the EPA to set its 70 parts per trillion (ppt) health advisory level for drinking water and upon which the EPA and Department of Defense previously based their screening levels.[1]

The EPA updates the RMLs and RSLs twice a year. Given how quickly scientific developments regarding PFAS are changing, the initial risk-based levels in the RSLs and RMLs are likely to change, and it can be expected that additional PFAS chemicals may be added as new risk assessments are performed. This is another step in the EPA’s efforts to address PFAS against the backdrop of additional expected federal action in the near term, including designating PFOA and PFOS as hazardous substances under CERCLA and developing a national primary drinking water standard for PFAS. The EPA’s addition of these five PFAS to its Superfund screening levels is also significant because it effectively reverses the agency’s decision to exclude RMLs from its 2019 interim groundwater cleanup guidance.

Companies that use and manufacture PFAS chemicals and companies involved at sites with PFAS contamination should watch for future additions to the RSLs and RMLs and expect further changes to the risk-based levels contained in the lists as the science evolves. Additionally, companies involved in both active and completed cleanups should expect to see increased interest in addressing PFAS from both federal and state regulators, and responsible parties can expect sites that may not have otherwise been identified to now require further action.


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[1] See United States Department of Defense, Investigating Per-and Polyfluoroalkyl Substances Within the Department of Defense Cleanup Program (September 15, 2021); EPA, Memorandum: Interim Recommendations for Addressing Groundwater Contaminated with Perfluorooctanoic Acid and Perfluorooctanesulfonate (December 19, 2019).