The U.S. Environmental Protection Agency (EPA) published an advance notice of proposed rulemaking (ANPRM) on April 13, 2023, seeking information to assist in the consideration of potential development of future regulations pertaining to per- and polyfluoroalkyl substances (PFAS) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). 88 Fed. Reg. 22399. EPA states that it seeks input and data regarding potential future hazardous substance designation under CERCLA of seven PFAS, besides perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), and their salts and structural isomers, or some subset thereof; precursors to PFOA, PFOS, and seven other PFAS; and/or categories of PFAS. Comments are due June 12, 2023. EPA notes that under the Paperwork Reduction Act, “comments on the information collection provisions are best assured of consideration if the Office of Management and Budget (OMB) receives a copy of your comments” by May 15, 2023.

Purpose of the ANPRM

EPA seeks input and data to assist in the potential development of future regulations pertaining to the designation of hazardous substances under CERCLA Section 102(a), which authorizes the EPA Administrator to promulgate regulations designating as hazardous substances such elements, compounds, mixtures, solutions, and substances that, when released into the environment, may present substantial danger to the public health or welfare or the environment. Specifically, the ANPRM seeks public input regarding the possible designation of:

• Seven PFAS besides PFOA and PFOS:

  • Perfluorobutanesulfonic acid (PFBS), Chemical Abstracts Service Registry Number^® (CAS RN^®) 375-73-5;

  • Perfluorohexanesulfonic acid (PFHxS), CAS RN 355-46-4;

  • Perfluorononanoic acid (PFNA), CAS RN 375-95-1;

  • Hexafluoropropylene oxide dimer acid (HFPO-DA), CAS RN 13252-13-6 (sometimes called GenX);

  • Perfluorobutanoic acid (PFBA), CAS RN 375-22-4;

  • Perfluorohexanoic acid (PFHxA), CAS RN 307-24-4; and

  • Perfluorodecanoic acid (PFDA), CAS RN 335-76-2;

• Precursors to PFOA, PFOS, and the seven PFAS listed above; and

• Categories of PFAS.

In EPA’s September 6, 2022, notice of proposed rulemaking (NPRM) designating PFOA and PFOS as hazardous substances, EPA noted that evidence indicates that these chemicals may present substantial danger to public health or welfare or the environment when released into the environment, thereby warranting designation under CERCLA Section 102(a). According to EPA, in reaching this determination, it considered a number of criteria, including adverse human health effects and mobility, persistence, and prevalence, in addition to other factors. EPA states that as mentioned in the NPRM, “it is not necessary to have information on all of these criteria for EPA to designate a PFAS compound as a hazardous substance under CERCLA.” EPA requests information on these factors in this ANPRM since it may be relevant and to guide public input. More information on the September 2022 NPRM is available in our August 29, 2022, memorandum.

In evaluating whether to designate additional PFAS as hazardous substances, different levels of information may exist for individual compounds or categories of PFAS with regard to adverse human health effects, mobility, persistence, prevalence, and other factors. According to EPA, some of this information is presented on its Comptox Dashboard. EPA states that it is seeking public input and additional information pertaining to these factors that it could consider in evaluating whether these PFAS may present substantial danger to the public health or welfare or the environment. EPA notes that it is not reopening for public comment or otherwise proposing to modify any proposed or existing regulatory actions through this ANPRM.

Information Requested by EPA

Request for Public Input Regarding Potential Future Hazardous Substance Designation of Seven Other PFAS

EPA is soliciting information relevant to whether the seven PFAS identified above and their salts and structural isomers may present substantial danger to public health or welfare or the environment. As an example, according to EPA, it requests information concerning the characteristics of these compounds, such as mobility, persistence, prevalence, and other characteristics, that would supplement the existing toxicity data for these compounds. EPA states that although PFAS is a large class of chemical substances, it identified these seven compounds based on the availability of toxicity information previously reviewed by EPA and other federal agencies.

To inform EPA’s decision whether to designate PFBS, PFHxS, PFNA, HFPO-DA, PFBA, PFHxA, and PFDA, or some subset thereof, as hazardous substances in a possible future action, EPA is soliciting responses to the following questions and requests that commentors provide supporting information and specific scientific literature citations regarding applicable information where appropriate:

1. Please identify additional relevant information in published scientific literature or data regarding the environmental fate and transport (mobility, persistence, or other relevant chemical and physical properties) and environmental prevalence that would assist EPA in making determinations regarding potential designation as a hazardous substance.

2. Are there other PFAS EPA could consider designating as hazardous substances in a possible future rulemaking? If so, please provide references to any published scientific information on the toxicity of these other PFAS in addition to the information requested in question one for those substances.

3. Please provide available information that EPA could consider in preparing an economic analysis of the potential direct and indirect costs and benefits, including impacts on small entities, associated with a potential rulemaking designating any of the above-mentioned compounds as hazardous substances. Although CERCLA Section 102(a) precludes EPA from taking cost into account in the designation of a hazardous substance, EPA requests this information to inform its understanding of the potential costs and benefits associated with any potential future regulatory action.

Request for Public Input Regarding Potential Future Hazardous Substance Designation of Precursors to PFOA, PFOS, and Certain PFAS

EPA states that it is also considering whether to initiate a future action that would potentially designate precursors to PFOA, PFOS, and possibly the seven PFAS and their salts and isomers, or some subset thereof, as hazardous substances. Thus, EPA is soliciting input regarding information that will assist it in identifying compounds that degrade to these PFAS through environmental processes such as biodegradation, photolysis, and hydrolysis.

According to the ANPRM, an example of how EPA has addressed precursors previously is the 2020 significant new use rule (SNUR) for long-chain perfluoroalkyl carboxylate (LCPFAC) PFAS that included salts and precursors of these perfluorinated carboxylates. EPA states that it explained, “LCPFAC precursors may be simple derivatives of perfluorooctanoic acid (PFOA) and higher homologues or certain polymers that may degrade to PFOA or higher homologues.” More information on the 2020 SNUR is available in our July 27, 2020, memorandum.

To inform EPA’s decision making regarding the potential designation of precursors to PFOA, PFOS, and possibly the seven PFAS, or some subset thereof, as hazardous substances, EPA requests responses to the following questions and topics described below and requests that commentors provide supporting information and specific scientific literature citations regarding applicable information where appropriate:

4. Please identify information in published scientific literature or data regarding the environmental degradation of substances to PFOA, PFOS, PFBS, PFHxS, PFNA, HFPO-DA, PFBA, PFHxA, and/or PFDA.

5. What factors, if any, regarding degradation time and environmental conditions (e.g., aqueous vs. arid, anaerobic vs. aerobic, available nutrients) should be considered in identifying the appropriate precursor compounds?

6. Please provide relevant information or data in published scientific literature that characterizes the environmental prevalence of PFOA, PFOS, PFBS, PFHxS, PFNA, HFPO-DA, PFBA, PFHxA, and/or PFDA from the degradation of associated precursors.

7. With respect to the preceding questions, please identify names and CAS RNs or Distributed Structure-Searchable Toxicity (DSSTox) substance identifiers for substances that EPA should consider as precursor compounds.

8. Available standard analytical methods, such as SW-846 Method 8327 or Method 533, may not include all precursors to PFOA, PFOS, PFBS, PFHxS, PFNA, HFPO-DA, PFBA, PFHxA, and/or PFDA. Furthermore, the development of additional methods may be limited by the availability of chemical standards. Given these limitations, please provide information regarding how precursors could be measured in environmental samples. Additionally, please comment on whether and how EPA should consider the availability of analytical methods when determining whether to designate precursors as CERCLA hazardous substances.

9. Please provide available information that EPA could consider in preparing an economic analysis of the potential direct and indirect costs and benefits, including impacts on small entities, associated with a potential rulemaking designating these precursors as CERCLA hazardous substances. EPA states that although CERCLA Section 102(a) precludes EPA from taking cost into account in the designation of a hazardous substance, “the Agency is requesting this information to inform its understanding of the potential costs and benefits associated with any potential future regulatory action.”

Request for Public Input Regarding Potential Future Designation, or Designations, of Categories of PFAS as Hazardous Substances

EPA states that it is considering whether to initiate a future action that would potentially designate groups or categories of PFAS as hazardous substances. Characteristics of interest could include, but are not limited to, chemical structure (e.g., carbon chain length, functional group), physical and chemical properties, mode of toxicological action, precursors or degradants, or co-occurrence.

EPA notes that its 2020 SNUR for LCPFAC provides an example of a category based on chemical structure. In the SNUR, EPA defines the LCPFAC category is defined as follows, where 5

1. CF₃(CF₂)_n-COO-M where M = H⁺ or any other group where a formal dissociation can be made;

2. CF₃(CF₂)_n-CH=CH₂;

3. CF₃(CF₂)_n-C(=O)-X where X is any chemical moiety;

4. CF₃(CF₂)_m-CH₂-X where X is any chemical moiety; and

5. CF₃(CF₂)_m-Y-X where Y = non-S, non-N heteroatom and where X is any chemical moiety.

In addition to the structures identified above, “The category also includes the salts and precursors of these chemical substances. The precursors may be simple derivatives of PFOA and higher homologues or polymers that contain or may degrade to PFOA or higher homologues. These precursors include long-chain fluorotelomers.” [80 Fed. Reg. 2885]. Thus, according to EPA, its 2020 SNUR for LCPFAC included certain PFAS based on their chemical structures, as well as other PFAS based on whether they degrade to the targeted LCPFACs.

To inform EPA’s decision whether to designate certain groups or categories of PFAS as hazardous substances, EPA solicits responses to the following questions and requests that commentors provide supporting information and specific scientific literature citations regarding applicable information where appropriate:

10. Please identify published scientific literature that can inform whether categories of PFAS could or could not be designated as hazardous substances. This could include, for example, scientific data or information on the similarities or differences of a specific characteristic among PFAS. This could also include scientific data and information on the relationship between different characteristics, such as the relationship between chemical structure and specific chemical, physical, or toxicological properties.

11. Is there other information that EPA should consider when determining whether to designate one or more categories of PFAS as hazardous substances? Please provide comment on the extent to which EPA could include related PFAS in a given category (e.g., structural isomers and/or salts).

12. Please provide available information that EPA could consider in preparing an economic analysis of the potential costs and benefits, including impacts on small entities, associated with a potential rulemaking designating categories of PFAS as hazardous substances. Although CERCLA Section 102(a) precludes EPA from taking cost into account in the designation of a hazardous substance, EPA requests this information to inform its understanding of the potential costs and benefits associated with any potential future regulatory action.

Next Steps

EPA states that it intends to review carefully all comments and information received in response to this ANPRM. Once that review is completed, EPA will supplement the collected information, as appropriate, with information that it has obtained independently to determine whether a future rulemaking should address the designation of additional PFAS or precursors as CERCLA hazardous substances or whether one or more categories of PFAS can be designated as CERCLA hazardous substances.

Commentary

We sound like a broken record, but this is a consequential initiative, and responding to EPA’s request for information is critically important. Whether, how, and when additional PFAS are identified as CERCLA hazardous substances only adds to the remediation crisis many are expecting derivative of the proposal to designate PFOS and PFOA as hazardous substances.

In this regard, EPA has requested information on inputs to its economic analysis, direct and indirect costs, and impacts on small business. These are all the right questions and data points to seek and consider.

Importantly also, EPA is seeking information on “groups” or “categories” of PFAS as hazardous substances. Any “category” should consider the collateral implications of such an approach for other regulatory initiatives. TSCA testing, for example, comes to mind.