Robert Sussman, a former Deputy Administrator of the U.S. Environmental Protection Agency (EPA) during the Clinton administration, advocated that PFAS (per- and polyfluoroalkyl substances) be treated as a class of chemicals rather than individually, an approach that could facilitate the regulation of f-gases and their degradation products.

Sussman made this point during a PFAS panel discussion at the ATMOsphere America 2023 Summit, held in Washington, D.C., June 12–13.

PFAS includes, by some estimates, up to 9,000 substances, which all share common attributes, notably persistence in nature (thus the moniker “forever chemicals”), mobility, accumulation and the potential for the same adverse effects as well-studied PFAS compounds like PFOA and PFOS.

The sheer size of the PFAS category makes it necessary to regulate it as a class,  said Sussman, who was also Senior Policy Counsel to EPA Administrator Lisa Jackson during the Obama administration and is currently the Principal of his consulting firm Sussman and Associates.

“Test data on most PFAS are limited or non-existent and testing all PFAS (or even a representative subset) would take years,” he noted. As a result, restricting PFAS one chemical at a time “would not prevent ongoing pollution and continuing build-up in people and the environment that lead to future cleanup and medical costs,” he added. “It’s not a workable approach to PFAS.”

The history of PFAS regulation also argues in favor of a class-based approach, Sussman said. A decade ago, concerns about PFAS focused on the original long-chain versions such as PFOA and PFOS. Short-chain PFAS were initially considered less harmful but now short-chain compounds like GenX are proving to be as problematic for human health as legacy PFAS, he noted.

Definition debate

Treating PFAS as a class requires a clear definition of PFAS, but definitions of these chemicals have fallen into two camps. In one camp, PFAS is narrowly defined  as containing at least 2 fully fluorinated carbon atoms, which excludes f-gases and trifluoroacetic acid (TFA), the atmospheric byproduct of certain f-gases.

A second, broader definition, accepted by most scientists and adopted by the EU and a number of U.S. states, says that PFAS contain at least one fully fluorinated methyl or methylene carbon atom; this definition, published in 2021 by the OECD (Organization for Economic Co-operation and Development), incorporates many f-gases and TFA.

The EPA in 2021 announced that it was using the narrower definition of PFAS but in May indicated it was dropping that definition and is “evolving toward ad hoc case-by-case definition,” said Sussman. More recently, the EPA proposed a new definition of PFAS that still incorporates at least two fluorinated carbon atoms. (Comments on this proposal can be made until July 20.) Meanwhile a U.S. Senate committee recently proposed a PFAS bill that adopts the narrower definition.

In the EU, the European Chemicals Agency (ECHA) is following the broader OECD definition as it considers a stricter regulation of PFAS as a class. In February it published a proposal from the national authorities of Denmark, Germany, the Netherlands, Norway and Sweden to restrict PFAS; the “Universal Restriction Proposal” would limit the manufacture, use or sale of certain f-gas refrigerants as substances on their own or in blends.

Sussman noted that the EU is covering all PFAS, defined broadly, and is presuming adverse effects without substance-specific assessments. It is looking at banning manufacture and use of PFAS, subject to essential use exemptions with phase-out periods between 18 months and 12 years. “It’s not a done deal – there’s a substantial period for public and industry input, negotiation among governments and further legal and technical analysis,” he pointed out.

Meanwhile, the U.S. is far from adopting EU-type class approach. Limited authority under existing law – the Toxic Substances Control Act – allows category-based regulation but is “cumbersome and complex,” Sussman said. “The EU is far ahead of the U.S. and the two systems are out of synch,” he said. Congress is very engaged on PFAS “but has shied away from PFAS class legislation despite some member interest and NGO pressure.” So far, the best approach has been litigation, which is putting pressure on leading PFAS producers.

Many have argued that the OECD/EU definition of PFAS should be adopted in the U.S. “The EPA is gun-shy, reluctant and nervous about using that definition,” said Sussman. A broad PFAS definition would capture HFCs and HFOs. “Is that the reason for opposition to the OECD definition within the EPA?” Sussman asked.

While the chemical industry gives the EPA “political cover” on the PFAS definition issue, that can be countered by the major users of non-fluorinated gases like natural refrigerants, Sussman said, adding, “Raising the profile of that industry is very important.”

The human toxicity of TFA, an ultra-short-chain PFAS, has not yet been confirmed; however, its toxic effect in green algae and lab animals has been documented and a number of studies point to its proliferation in the environment. In Germany, a drinking water guide of 60mcg/l and a pre cautionary measure of 10mcg/l have been set. Still, “until the evidence of [human TFA] toxicity is stronger than it is now, the folks advocating for f-gases will argue that the evidence is still not there,” noted Sussman.

Meanwhile, as key questions remain unresolved and long-term policy is uncertain, “no one knows what the PFAS ‘end game’ will look like,” said Sussman.

“Test data on most PFAS are limited or non-existent and testing all PFAS (or even a representative subset) would take years.”

Robert Sussman, Principal, Sussman and Associates and former EPA Deputy Administrator