OECD PFAS Definition

The Organisation for Economic Co-operation and Development (OECD) defines PFAS as “fluorinated substances that contain at least one fully fluorinated methyl (–CF3) or methylene (–CF2–) carbon atom (without any H/Cl/Br/I atom attached to it).” This 2021 definition is the broadest widely-adopted PFAS definition, covering an estimated 10,000+ substances. It serves as the basis for the EU’s universal PFAS restriction proposal under REACH and is the most commonly referenced definition in international regulatory and scientific contexts.

OECD (2021) ENV/CBC/MONO(2021)25 “Reconciling Terminology of the Universe of Per- and Polyfluoroalkyl Substances.”

The OECD definition is broader than both the EPA’s TSCA definition and the NDAA definition. It captures substances with as few as one fully fluorinated carbon, including some that EPA’s definition excludes (e.g., trifluoroacetic acid). For companies operating globally, the OECD definition is effectively the standard to screen against—if a substance meets the OECD definition, it will likely fall within scope of one or more jurisdictional PFAS regulations. Using the OECD definition as the screening baseline provides the broadest compliance coverage.

A chemical company screens its portfolio against the OECD definition and identifies that a product containing only a single –CF3 group qualifies as PFAS under the OECD definition and the EU restriction proposal, but would NOT qualify under EPA’s TSCA 8(a)(7) definition. For EU market access, OECD-based screening is essential.