What are PFASS and what are they used for?
Per- and polyfluoroalkyl substances (PFASs) are a large group of chemicals widely used in industrial and consumer applications since the 1950s, most usually where extremely low surface energy or surface tension and/or durable water- and oil-repellency is needed, e.g., chromium metal plating, various fire-fighting foams, or for surface treatment of textiles, carpets and papers.
PFASs consist of a fully (per) or partly (poly) fluorinated carbon chain connected to different functional groups. Based on the length of the fluorinated carbon chain, short and long chain PFASs can be distinguished. Long chains refers to:
- perfluorocarboxylic acids (PFCAs) with carbon chain lengths C8 and higher, including perfluorooctanoic acid (PFOA);
- perfluoroalkane sulfonic acids (PFSAs) with carbon chain lengths C6 and higher, including perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonate (PFOS); and
- precursors of these substances that may be produced or present in products.
The length of the fluorinated carbon chain can result in different physicochemical properties that influence the substance behaviour in the environment and in organisms, and its bioaccumulation and (eco) toxicity.
The figure provides a classification of per- and polyfluoroalkyl substances (PFASs) based on a commonly agreed terminology for nomenclature of PFASs.
A risk for the environment, health and safety
Some of the unique physicochemical properties of per- and polyfluoroalkyl substances (PFASs) (such as water-, oil- and grease-repellence and high thermal stability) that popularised their widespread use are associated with environmental and human health concerns.
For over a decade, PFASs, in particular PFSAs and PFCAs, such as PFOS and PFOA, and their precursors have attracted the most attention among PFASs as emerging contaminants of global concern.
These substances are persistent and distributed ubiquitously in the global environment, biota and humans, and in remote areas (i.e. they have high long-range transport potential); they are bioaccumulative and can cause various adverse effects in wildlife and humans and have been detected in wildlife, as well as in the blood of neonates.
These findings are of particular concern in view of the known behaviour of these compounds, their persistency, the toxicological profile of certain PFASs, and their potential to accumulate in the body and in food chains.
As a result, PFASs are monitored worldwide, both in the environment and in organisms.
Non-polymeric per- and polyfluoroalkyl substances (PFASs)
Table 1. Overview of major historical and current uses of non-polymeric per- and polyfluoroalkyl substances (PFASs)*
| INDUSTRY BRANCH | NON-POLYMER | ||
| 1. Aviation, aerospace & defense | additives in aviation hydraulic fluid |
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| 2. Biocides | active ingredient in plant growth regulators or ant baits; enhancer in pesticides formulations |
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| 3. Construction products | additives in paints and coatings | additives in paints and coatings | |
| 4. Electronics | flame retardants |
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| 5. Fire-fighting | film formers in AFFF |
film formers in AFFF and in FFFP |
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| 6. Household products | wetting agent in floor polishes | wetting agent or surfactant in products such as floor polishes and cleaning agents | wetting agent or surfactant in products such as floor polishes and cleaning agents |
| 7. Metal plating | wetting agent, mist suppressing agent |
wetting agent, mist suppressing agent |
wetting agent, mist suppressing agent |
| 8. Oil and mining production | surfactants in oil well stimulation |
surfactants in oil well stimulation |
surfactants in oil well stimulation |
| 9. Polymerisation | (emulsion) polymerisation processing aids |
(co)monomer of side-chain fluorinated polymers |
(co)monomer of fluoropolymers & side-chain fluorinated polymers |
Source: This table is an extract from the Synthesis paper on per and polyfluorinated chemicals (PFCs) (see below).
*Note: Some uses may be obsolete and replaced by (non)fluorinated alternatives, which are discussed in Chapter 3 of the Synthesis paper (see below).
AFFF = aqueous film-forming foams
FFFPs = film-forming fluoroprotein.
Synthesis paper on per and polyfluorinated chemicals (PFCs)
Polymeric per- and Polyfluoroalkyl substances (PFASs)
Table 2. Overview of major historical and current uses of polymeric per- and polyfluoroalkyl substances (PFASs)*
| INDUSTRY BRANCH | POLYMER | ||
| 1. Automotive | raw materials for components such as low-friction bearings & seals |
lubricants |
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| 2. Aviation, aerospace & defense | insulators; "solder sleeves" |
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| 3. Cable & wiring | coating for weathering, flame and soil resistance | surface-treatment agent for conserving landmarks |
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| 4. Construction |
coating of architectural materials (fabrics, metals, |
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| 5. Electronics | insulators; “solder sleeves”; |
vapor-phase soldering media |
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| 6. Energy |
film to cover solar collectors due to weatherability |
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| 7. Fire-fighting |
raw materials for fire-fighting equipment, including |
fuel repellents for FP & foam stabilizers in AR-AFFF and |
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| 8. Food processing | fabrication materials |
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| 9. Household products | nonstick coating |
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| 10. Medical articles |
surgical patches |
stain- and water-repellents for surgical drapes and |
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| 11. Paper and packaging | oil and grease repellent |
oil and grease repellent |
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| 12. Semiconductors | raw materials for equipment |
working fluid in mechanical vacuum pumps |
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| 13. Textiles, leather and Apparel | raw materials for highly porous fabrics |
oil and water repellent and stain release |
working fluids in mechanical vacuum pumps |
Source: This table is an extract from the Synthesis paper on per and polyfluorinated chemicals (PFCs) (see below).
*Note: Some uses may be obsolete and replaced by (non)fluorinated alternatives, which are discussed in Chapter 3 of the Synthesis paper.
AR-AFFF = alcohol-resistant aqueous fire-fighting foams
FFFPs = film-forming fluoroprotein
FP = fluoroprotein foam