Nothing lasts forever—except “Forever Chemicals.” These substances resist water, oil, chemicals, and heat but persist in the environment and accumulate in bodies.
You can also read: Fluorination in Packaging and PFAS Contamination.
Chemists call these chemical compounds per- and poly-fluoroalkyl substances (PFAS). It all started with the discovery of Polytetrafluoroethylene (PTFE) on April 6, 1938, often called Teflon, by a young chemist named Roy Plunkett at E.I. du Pont de Nemours laboratory in Deepwater, New Jersey, and commercialized in 1946. The discovery did not stop there. Exploiting the strength and qualities of fluorinated compounds, a family of fluorinated substances was born called PFAS.
There are mainly two types of PFAS: polymers such as PTFE, PVDF, and FKMs (Fluoropolymers) and non-polymers such as perfluoroalkyl and poly-fluoroalkyl substances.
Anatomy of PFAS.
Fluoropolymers can be homo- or copolymers. Fluoropolymers are less affected by the van der Waals forces as hydrocarbon polymers (PE, PP) which give them non-stick and friction-reducing properties. All PFASs are not the same. Their properties vary depending on their chemical structures. Current attention, however, is more on non-polymer type PFAS (2-10 fluorocarbon repeat units).
Perfluoroalkyl substances (subclasses) are full of fluorine atoms (fluorinated), whereas polyfluoroalkyl substances are partially fluorinated (at least one). The culprit, however, is the strength of carbon-fluorine (C-F) bonds. This strength gives them a highly stable chemical structure; with that comes the resistance to breaking down and persistent. That is why these chemicals are dubbed “Forever chemicals” or simply PFAS. In fact, PFAS is a family of thousands of chemicals. The Organization for Economic Co-operation and Development (OECD) states PFAS as a class of “fluorinated chemicals that contain at least one fully fluorinated methyl or methylene carbon atom”. To better understand these chemicals, there are three parts to each of the PFAS that one must evaluate.
Three questions to answer about PFAS structure.
PFAS are further classified as long or short-chain PFAS depending on the number of perfluorocarbon units. Each chain type has significantly different properties. Researchers, however, are primarily involved in finding and separating widely used PFOA (perfluorooctanoic acid) and PFOS (perfluoroctane sulfonate), C8 group members of PFAS.
Chemical structures of perfluorooctanoic acid (PFOA) and perfluoroctane sulfonate (PFOS). Courtesy of Removal of per- and polyfluoroalkyl substances (PFAS) from water by ceric(IV) ammonium nitrate.
PFAS are too diverse to be grouped. They are used in hundreds, if not thousands, of applications, including air conditioning, ammunition, automotive, carpets, cleaning agents, coatings, cookware, firefighting foams, floor coverings, leather, medical utensils, plastics processing, food packaging, pesticides, soldering, sports articles, textiles, water, and effluent treatment.
It is the toxicity. The notoriety of PFAS is further exacerbated due to their ability to persist (persistence) and bio accumulativeness. Depending on dose and duration, PFAS can exert adverse effects on the function of an organ or organ system or can cause overall mortality or morbidity. Decades of research continually show an array of health effects, including liver damage to some cancers arising from PFAS exposure. According to the Environmental Protection Agency’s (EPA) website, health effects of PFAS include reproductive effects (decreased fertility, increased blood pressure in pregnant women), developmental effects/delays in children (low birth weight, accelerated puberty, etc.), increased risk of some cancers (including prostate, kidney, and testicular), reduced immune functions to fight infections, including reduced vaccine response, increased cholesterol levels and/or risk of obesity. Of course, the list is long, but it shows the severity of PFAS exposure.
You can also read: Is It Safe To Incinerate Fluoropolymers?
There are many apparent reasons for this. First and foremost, historically, research has documented the toxicity of PFAS. Products such as water-proof jackets, wrinkle-free shirts, non-stick pans, etc., were sold. From manufacturers to users to final disposal – all contribute to controlled and uncontrolled release of PFAS to waste streams and the environment. The existence and use of PFAS span decades of manufacturing, making them easy to locate. They have been found in drinking water sources in all 50 states in the USA.
The United States Geological Survey reported (2023) that, on average, at least one PFAS is detected in about 45% of US drinking water samples. Centers for Disease Control and Prevention (CDC) showed that most people in the United States have been exposed to some PFAS. Blood plasma samples of youth and adults in the Arctic region of Nunavik, Canada, showed multiple-fold higher PFASs compared to the general Canadian population
You can also read: Plasma concentrations of perfluoroalkyl acids and their determinants in youth and adults from Nunavik, Canada.
Then there is the news of litigations, just like tobacco products and asbestos. The New York Times headline (May 28, 2024) read, “Damages from PFAS lawsuits could surpass asbestos, industry lawyers warn”. Companies are settling PFAS-related suits by offering billions of dollars. 3M Co reached a $10.3 billion settlement in 2023 with numerous U.S. public water systems to resolve water pollution claims, which will help support remediation that detects PFAS.
You can also read: 3M reaches tentative $10.3 billion deal over US ‘forever chemicals’ claims | Reuters.
Furthermore, In 2024, Tyco Fire Products LP reached a $750 million settlement in a PFAS lawsuit. According to Times Magazine (July 12, 2023), the settlement news goes back to 2001 (Tennant and DuPont). History catches up.
Multi-layer LDPE Blown film bubble. Courtesy of Evaluation of 9-Layer Film Blowing Process by Using Variational Principles.
Many valuable properties, as well as the durability of plastics, come from fluorinated compounds. PFASs are costly to produce, but a very small amount can provide the same performance as a much more considerable amount of non-fluorinated compounds. Fluoropolymers help process polymers, improve stability, and provide product functionality. Melt fracture can happen in all extrusion-based processes.
A tiny amount of processing aid (0.1%) helps process plastics, avoids melt fracture, plate out, gel reduction, and increased throughput, and gives the product the surface finish it requires. Philip S. Blatz first patented (US3125547A) fluorocarbon polymer (Viton A) in 1964 to avoid melt fracture at a higher extrusion rate. PFAS-based process aids (PPA) are still in use. Although PPA is widely used in LLDPE blown film, it is also used in many other polymers (LDPE, HDPE, PP, PS, nylon, PVC, CPVC, acrylics, and others) and in processes such as blow, injection, profile extrusion, etc.
Manufacturers use fluorosurfactants, such as PFOA, in PTFE production. PTFE functions as an anti-dripping agent in flame retardant formulations. Additionally, it is incorporated into polycarbonate (PC) and its alloys, which are widely used in automotive, aerospace, electronics, and consumer goods applications.
In the cable industry, fluorinated polymer (FEP) is often used as the outer layer structure for insulation. Not only insulation and heat resistance, FEP provides chemical, UV, ozone, and abrasion resistance. PVDF is sought after in industrial piping systems for all these attributes, including low maintenance. As alternatives, liquid contact walls of HDPE and PP containers are directly fluorinated in some products to avoid the higher cost of fluoropolymer-based products.
Paints and sealants can contain PFAS, as these fluorinated compounds lower the surface tension, which helps spread the fluid and provides stain resistance. When used as binders, PFAS reduces bubbling and peeling. PFAS-containing water—and solvent-based adhesives provide full contact between joining surfaces and avoid foaming.
Moreover, mold-release agents are crucial in plastic molding, especially for high-temperature polymers like PPS, PPSU, PES, PEEK, and CPVC. PFAS are sometimes included in these mold release agents.
PPA suppliers such as Baerlocher, Momentive, Ampacet, Kafrit, Techmer PM, Tosaf, Clariant, and Dover Chemical, including PE resin supplier Nova Chemicals, Sabic, claim to have PFAS-free products. Processors like TenCate, which makes synthetic grass for sports (artificial turf) and landscapes, have replaced PFAS with PFAS-free chemicals in their synthetic grass manufacturing.
Avient corporation’s Cesa flame retardant additives for polycarbonate are PTFE free, which will help the electrical & electronics product manufacturers. They also claim their additives are even suitable for recycled content and can help achieve GWFI temperatures up to 960°C (IEC 60695-2-12 test protocol).
You can also read: Avient Unveils PTFE-Free and Non-Halogen Flame Retardants for Polycarbonate at Fakuma 2023 | Avient.
Recently, LG Chem reported PFAS-free flame-retardant products for PC/ABS blends, which received a V-0 rating UL-94 test. Also, Trinseo and FRX Innovations have claimed PFAS-free alternative flame-retardant products.
The current material developmental trend has been PFAS-free additives. Even PFAS-free mold release agents and lubricants are available from McLube and Miller-Stephenson. Non-fluorinated alternative binders in both liquid paint and powder coats are available in acrylics, alkyds, and epoxies. PFAS-free alternatives such as mineral spirits and aromatic petroleum distillates exist to improve paint viscosity and spread. Fluorine-free polymers, such as polyether ether ketone (PEEK), offer high heat resistance, chemical durability, and strong mechanical or electrical properties for demanding applications.
Products touted as PFAS-free are appearing in the market. Tranemo Textil of Sweden has phased out the majority of FR fabrics and switched to PFAS-free FR fabrics. Environmental Working Group (EWG) has reviewed and compiled a list of products (baby products, cookware, personal care, carpets, durable water repellant, eye care, fire suppressant/gear, food packaging, and so on) along with company brand names that do not use PFAS and/or fluorinated products. EPA has a list of PFAS-free cleaning products certified by its Safer Choice program.
Big companies are commiting with this issue. In a press release 3M announced that it will exit PFAS manufacturing and discontinue the use of PFAS across its product portfolio by the end of 2025. (Press release, St. Paul, Minnesota, December 22, 2022). Moreover, Apple is committed to phasing out PFAS from its products and processes. (November 2022).
Also, in a public release on July 8, 2024 (GAO-24-107322), the US Government Accountability Office (GAO) stated, “DOD discontinue use of AFFF at its installations after October 1, 2024 – with waivers possible until October 1, 2026.” Further, the Dept. of Defense (DOD) has developed specifications for developing a fluorine-free foam that provides a PFAS-free alternative for meeting DOD’s fire extinguishing performance standards. “DOD uses AFFF in about 1,500 facilities and over 6,800 mobile assets worldwide to suppress fires,” – the release read.
In February 2024, the Food and Drug Administration (FDA) announced a ban on using PFAS-containing grease-proofing materials in new food packaging. The ban applies to microwave popcorn bags, fast-food wrappers, and takeout boxes sold to U.S. consumers.
You can also read: FDA Announces PFAS Used in Grease-Proofing Agents for Food Packaging No Longer Being Sold in the U.S. | FDA.
Although the advisory is voluntary, manufacturers have committed to the FDA to stop selling certain types of PFAS for food-contact applications. The FDA is developing a validated analytical method for monitoring packaged food.
In April 2024, the EPA designated PFOA and PFAS as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act and issued legally enforceable drinking water standards.
You can also read: PFAS Explained | US EPA.
Regulators have set maximum concentration levels at 4 parts per trillion (ppt or ng/L) for PFOA and PFOS, and 10 ppt or ng/L for PFHxS, PFNA, and HFPO-DA (GenX Chemicals).
EPA has developed and provided different test methods for detecting and measuring:
The challenge is how legislation and regulations work at state levels. All PFAS are not equal fueling debate and inconsistencies. Not an easy task to identify different categories of products (consumer, industrial, or commercial) and then measure, separate, and dispose based on toxicity, persistence, and bio-accumulative. Moreover, Canada has recently updated its Updated draft state of per- and polyfluoroalkyl substances (PFAS) report.
You can also read: U.S. PFAS Regulations by State for Consumer Products.
Like in North America, European regulations continue to evolve. In Europe, it is called REACH, which stands for Registration, Evaluation, Authorisation, and Restriction of Chemicals. According to REACH, the burden of proof on human health and environmental risks rests on companies. Companies must register their chemicals and work together to register the same substance. In November 2024, newly identified uses were reported, which included sealing (pipe-lining, gaskets), technical textiles (outdoor applications like tarps), printing, and other medical packaging-related medical applications. These applications involve products made of thermoplastics, elastomers, and thermoplastic elastomers. For more information, Roland Berger has put together PFAS limits across the European Union.
PFAS are synthetic materials containing over 12,000 different compounds, if not more. The problem has been developing for years and will take time to address.
The complexity lies in identification, separation, destruction, phasing out, and its replacements. Regulations only will not solve the issue. Manufacturers need to be vigilant and develop a risk-mitigated communication strategy. Any product innovation will require safe and sustainable solutions. Only a serious, science-backed, multi-prong approach can address this multifaceted issue. Ultimately, we need to see each tree and not the forest.
Article by: Prithu Mukhopadhyay, Ph.D. Editor-in-Chief Journal of Vinyl & Additive Technology.
Edited for online version by: Juliana Montoya MSc.
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