A controversial project to redefine the family of environmentally persistent chemicals known as per- and poly-fluoroalkyl substances (PFAS) continues to divide opinions among the chemistry community. While some believe that standardising the language used to define PFAS will enable clearer and more effective regulation of the substances, others are concerned that any new definitions will be too narrow and have questioned the motives of those behind the initiative.
Back in June, 20 world experts in PFAS issued a public statement expressing serious concerns about the project, which is being led by the International Union of Pure and Applied Chemistry (Iupac). The statement’s authors were worried that the effort is ‘politically and/or economically, rather than scientifically motivated’ and that any new definitions could be used by ‘parties with vested interests to influence regulations’.
At the American Chemical Society (ACS) meeting in Washington, DC on 19 August the ACS invited attendees to participate in a townhall discussion about the definition of PFAS and hear about the status of this Iupac initiative.
Vetted by the community
With none of the Iupac project team available to attend the meeting, the discussion was led by Michelle Rogers, an industrial regulatory and scientific affairs manager for agrobusiness giant Cargill, who currently sits on Iupac’s science board.
‘Based on my experience with Iupac, they are exceptionally thoughtful in the way that they build recommendations,’ stated Rogers. She noted that the organisation consistently seeks input from the broader scientific community and takes that feedback very seriously.
‘I personally, having worked with Iupac now for almost 20 years, don’t have a concern [because] they will work very closely with the international community to make sure any new official recommendations of terminology or nomenclature have been well-vetted within the global community,’ Rogers added.
She and others affiliated with Iupac also emphasised that the organisation is non-governmental and not-for-profit and doesn’t receive money to charter its projects from any entities that have any specific interests. This ensures that its work is free from bias, they said.
Iupac’s past president Javier García-Martínez, an inorganic chemist based at the University of Alicante in Spain, echoed these sentiments.
‘Once an Iupac committee approves a project, there is a task force created and it is up to that task force to interview whatever experts within the field that they may need,’ he stated.
García-Martínez added that these task forces are typically composed of 10 members who are ‘very global and very diverse’.
But Jamie DeWitt, an environmental and molecular toxicologist at Oregon State University who is one of authors of the June statement sounding an alarm about the Iupac project, remains sceptical.
‘I stand by the assertions and opinions in the published statement,’ she tells Chemistry World. ‘The Organisation for Economic Co-operation and Development’s PFAS definition is scientifically sound and based on “intrinsic molecular features”. It is not a definition that is motivated by politics, economics, and/or regulation and was developed with input from myriad sectors representative of the global chemistry community.’
Dizzying definitions
According to Rogers, the global chemistry community needs a unifying set of terminology for PFAS because of the many competing definitions that are used for such substances in regulations around the world.
For example, the OECD defines PFAS as any molecule that contains a single fully fluorinated carbon, which can include a carbon with two fluorines in the middle of a chain, or a terminal trifluoromethyl group.
But in the US a substance must have at least two adjacent fully fluorinated carbons to be considered a PFAS nationally , Rogers stated. Such deviations mean, for example, that trifluoroacetic acid (TFA) is not a PFAS according to the US Environmental Protection Agency, but it is considered a PFAS by OECD, she said.
There is even conflict within the US, where many of the country’s 50 states have adopted alternative PFAS definitions that do include TFA.
At the townhall discussion, Rogers noted that many US states have PFAS bans or reporting requirements coming into force in the coming years that must be met by industry. She estimated that, as of mid-July, nine states have adopted 17 new PFAS regulations and approximately 36 states are considering more than 200 bills to regulate these substances.
‘For industry this is a challenge because each state has its own definition, its own list of exceptions, and therefore companies are investing lots of time and energy and making sure they can comply with these or choosing to withdraw products completely from the market to not have to deal with these requirements,’ Rogers stated.
But DeWitt notes that the various legal definitions of PFAS that are used in regulations may differ from a chemical definition, and because there already is a sound chemical definition for these chemicals she says ‘it doesn’t seem feasible … that another chemical definition could be derived for PFAS’.
And DeWitt points out that, irrespective of the project, regulatory or decision-making bodies around the world could still end up relying on PFAS definitions that differ from the one that Iupac eventually settles on.
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