Understanding and acting on PFAS

Features
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In a post on The Glue Blog, Andrew Stooksbury, global regulatory director describes Perfluoroalkyl and polyfluoroalkyl substances (PFAS) as a group of chemicals used in coatings, textiles, firefighting foam, and many other applications.

(Image credit: AdobeStock by Francesco Scatena)

The group of chemicals are sought after for their resistance to heat, oil, and water.

Most of the attention focused on PFAS pertains to a subset of PFAS chemicals known as per- or polyfluoroalkly acids, which are potential degradation products of larger PFAS molecules.

Two of the most well-known examples of this group are PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid), which are generally understood as PFAS of concern. Globally regulating bodies are building definitions of PFAS as they continue to grow in concern. These definitions are not consistent, but they are similar.

PFAS Definitions to Consider

UN Stockholm Convention Persistent Organic Pollutants (POPs) – 3+ substances

  • Perfluorooctanoic acid (PFOA): CAS# 335-67-1
  • Perfluorooctane sulfonic acid (PFOS): CAS# 1763-23-1
  • Perfluorohexane sulfonic acid (PFHxS): CAS# 355-46-4

*Including their salts and “related compounds”

The International Chemical Secretariat SIN (Substitute It Now) List – 416 substances

  • Perfluorooctanoic acid (PFOA): CAS# 335-67-1
  • Perfluorooctane sulfonic acid (PFOS): CAS# 1763-23-1
  • Perfluorohexane sulfonic acid (PFHxS): CAS# 355-46-4

*Including their salts and “related compounds”

California Proposition 65 – 1006 substances (as of November 17, 2023)

  • In 2017, perfluorooctanoic acid (PFOA) and Perfluorooctane Sulfonate or Perfluorooctane Sulfonic Acid (PFOS), along with their salts and transformation and degradation precursors, were identified by California as reproductive toxins and added to the list. Later, both PFOA and PFOS's listings were broadened to qualify as carcinogens as well.
  • On 31 December 2021, the state added perfluorononanoic acid (PFNA) and its salts to the list.

OECD 2017 – 4,730 substances

  • PFASs are defined as fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e., with a few noted exceptions, any chemical with at least a perfluorinated methyl group (–CF3) or a perfluorinated methylene group (–CF2–) is a PFAS. You can view the list here.

US EPA Toxic Release Inventory (TRI) List – 200+ substances

  • 200+ total PFAS materials

EU “Universal” PFAS Restriction – 10,000 substances

  • Per- and polyfluoroalkyl substances (PFASs) defined as: Any substance that contains at least one fully fluorinated methyl (CF3-) or methylene (-CF2-) carbon atom (without any H/Cl/Br/I attached to it).
  • A substance that only contains the following structural elements is excluded from the scope of the proposed restriction:
  • CF3-X or X-CF2-X’,
  • where X = -OR or -NRR’ and X’ = methyl (-CH3), methylene (-CH2-), an aromatic group, a carbonyl group (-C(O)-), -OR’’, -SR’’ or –NR’’R’’’,
  • and where R/R’/R’’/R’’’ is a hydrogen (-H), methyl (-CH3), methylene (-CH2-), an aromatic group or a carbonyl group (-C(O)-).
  • The registry includes 10,000 substances.

This article first appeared in H.B Fuller’s website.