On May 18, 2022, U.S. EPA updated its Regional Screening Level tables to include five new per- and polyfluoroalkyl substances (PFAS). The five new PFAS compounds added to the RSL tables are hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA – sometimes referred to as GenX chemicals), perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS). U.S. EPA added its first PFAS substance, PFBS or perfluorobutanesulfonic acid, to the RSL tables in 2014 and updated that listing in 2021 when U.S. EPA released its updated toxicity assessment for PFBS.
The RSLs are risk-based screening values for residential and industrial soils and tap water that U.S. EPA relies upon to help determine if remediation is necessary. Although U.S. EPA is quick to point out that the RSLs are not cleanup standards, regulators at both the state and federal levels rely on these RSLs to drive decision-making at contaminated sites. The regulators also rely on these RSLs notwithstanding that U.S. EPA has yet to officially designate any PFAS as a CERCLA hazardous substance or RCRA hazardous waste (although efforts are ongoing on both fronts--CERCLA hazardous substances / RCRA hazardous wastes).
U.S. EPA set the screening levels for PFOA, PFOS, PFNA, and PFHxS based on the Minimal Risk Levels from the Agency for Toxic Substances and Disease Registry's toxicological profiles. The screening level for HFPO-DA was set based on a final, peer-reviewed toxicity value. For example, the screening level for PFOS is set at 38 parts per trillion for tap water and 1.6 parts per million for industrial soils and the screening level for PFOA is set at 60 parts per trillion for tap water and 2.5 parts per million for industrial soils
As we await further U.S. EPA action with respect to regulating PFAS under RCRA and CERCLA, it is interesting to note that U.S. EPA is currently engaged in a significant information gathering exercise related to historical PFAS use. Relying on its authority under CERCLA Section 104(e), U.S. EPA has recently issued scores of information requests seeking information regarding facilities' past PFAS uses and practices. The use of these information requests is consistent with the statements in U.S. EPA's 2021 PFAS Roadmap where U.S. EPA indicated that it intended to rely on its various enforcement tools to identify and address PFAS releases.
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