PFAS Grouping: An Emerging Scientific Consensus
PFAS/Fluorotechnology Enables Life in the 21st Century
According to the U.S. Environmental Protection Agency, “approximately 600 PFAS are manufactured (including imported) and/or used in the United States.” Among these 600 are substances in the solid (e.g., fluoropolymers), liquid (e.g., fluorotelomer alcohols) and gaseous (e.g., hydrofluorocarbon refrigerants) forms. The fundamental physical, chemical, and biological properties of solids, liquids and gases are clearly different from one another. The very distinct physical and chemical properties of the three types of commercial PFAS described demonstrate how varied they are and how a simple grouping approach to risk would be inadequate.
However, some have proposed grouping all PFAS chemistries together for the purposes of regulation. Although the grouping of some substances within the class based on similar physical, chemical, and biological properties may be possible – a proposal to regulate all PFAS as a single class is neither scientifically accurate nor appropriate
Latest Research Reveals Flaws in Grouping
But don't take our word for it.
In a recently published peer review conducted by a panel of experts, most agreed that all PFAS should not be grouped together for risk assessment purposes. Most experts also agreed that it is inappropriate to assume equal toxicity/potency across the diverse class of PFAS.
The US EPA’s PFAS Strategic Roadmap and National PFAS Testing Strategy also recognize distinctions within the broad class of PFAS and describe actions the agency will take to gather information on sub-categories within the broader class.
Furthermore, a scientific consensus is emerging that it is not accurate or even possible to group all PFAS chemistries together for the purpose of regulation. Indeed, state, federal and international entities that have explored the possibilities of a class-based approach have recognized significant challenges.
For instance:
- The Organisation for Economic Co-operation and Development (OECD) issued a report1 saying, “As PFASs are a chemical class with diverse molecular structures and physical, chemical and biological properties, it is highly recommended that such diversity be properly recognized and communicated in a clear, specific and descriptive manner.”
- ECOS2 – the Environmental Council of the States – which represents state and territorial environmental agency leaders, several of whom have implemented regulatory programs in their home states, has said: “Many regulators and subject-matter experts advise against grouping PFAS as an entire class.”
- The Vermont Department of Environmental Conservation3, which was specifically charged by the legislature to develop a class regulation or to explain why such a regulation wasn’t possible said, “The Review Team spent over a year deliberating, researching, and discussing the potential to regulate PFAS as a Class. After reviewing the current peer-reviewed literature, as well as the available toxicology data for PFAS, the Review Team determined that at the current time it is not feasible to regulate PFAS as a Class.”
- And federal scientists participating in a workshop convened last fall by the National Academies of Science, Engineering, and Medicine (NASEM) to review the federal PFAS research program acknowledged the broad diversity of properties with this group of substances, concluding that4 “PFAS substances thus present unique challenges for grouping into classes for risk assessment.”
- These state and federal entities findings are also echoed in a recent scientific, peer-reviewed publication5 evaluating possible grouping frameworks to assess PFAS.
1. https://www.oecd.org/chemicalsafety/portal-perfluorinated-chemicals/terminology-per-and-polyfluoroalkyl-substances.pdf
2. ECOS. Processes & Considerations for Setting State PFAS Standards (February 2020).
3. https://dec.vermont.gov/sites/dec/files/PFAS/20180814-PFAS-as-a-Class.pdf.
4. NASEM. Workshop on Federal Government Human Health PFAS Research, October 26-27. Board on Environmental Studies and Toxicology (2020).https://www.nap.edu/read/26054/chapter/1.
5. Goodrum PE et al. Application of a framework for grouping and mixtures toxicity assessment of PFAS:a closer examination of dose additivity approaches. Toxicol Sci: 1-19 (2020). https://doi.org/10.1093/toxsci/kfaa123.