PFAS in seals: what you need to know

What are PFAS?

Per- and polyfluoroalkyl substances (PFAS) are an extensive group of synthetic chemicals that have been developed and manufactured since the late 1940s. These compounds are characterized by their high chemical stability and longevity, which is why they are used in a wide range of industrial and commercial applications.

PFAS are widespread in the environment and in many consumer goods, which has led to concerns about their effects on human health and the environment. Because of their ability to repel water, oil and dirt, they are used in products such as cookware, water-repellent clothing and firefighting foams. Their presence in the environment is increasingly recognized as a global problem, as they can accumulate in water, soil and living organisms.

Definition and composition

• General definition: PFAS is the abbreviation for per- and polyfluoroalkyl substances, a group of over 10,000 synthetic chemicals, some of which have been banned in the EU since 2006. These chemicals are very persistent and break down only very slowly.
• Chemical structure: Per- and polyfluorinated alkyl compounds are aliphatic organic compounds in which, on at least one carbon atom, the hydrogen atoms have been completely replaced by fluorine atoms.
• Carbon-fluorine bonds: The carbon-fluorine bonds contained in fluoroalkyls are among the strongest chemical bonds in organic chemistry.

Diversity and number

Estimates of the number of individual PFAS compounds vary. While some estimates cite over 12,000 individual substances, other estimates put the PFAS group at more than 10,000 different substances.

Properties, manufacturing and use

Because of their special properties, perfluorinated chemicals (PFC) are used in numerous industrial processes and technical applications, including the manufacture of water-, grease- and dirt-repellent products, in electronic devices, cosmetic products, impregnating agents and in many other areas.

Where are PFAS found?

Because of their unique chemical properties, PFAS are found in a wide variety of consumer goods and industrial products. This omnipresence has led to widespread environmental contamination.

Everyday products

• Cookware: Non-stick pans and pots are often coated to enhance their non-stick properties.
• Textiles: Waterproof clothing such as rain jackets, as well as stain- and dirt-repellent carpets and upholstery fabrics, frequently contain fluoroalkyls.
• Packaging materials: Some food packaging, in particular fast-food packaging, is coated to prevent liquids and greases from seeping through.

Industrial applications

• Firefighting foam: PFAS are used in certain types of firefighting foams, especially in fires involving petroleum products.
• Electronics: In the electronics industry, PFAS are used for their water- and heat-repellent properties.
• Construction: Certain types of paints, varnishes and sealants contain PFAS.

Environmental pollution and regional differences

• Soil and water: These substances can enter the soil and groundwater through industrial waste, firefighting foam and agricultural practices.
• Air: Some perfluorinated chemicals can be released into the air and contribute to air pollution.
• Industrial areas: Regions with high industrial activity often show higher PFAS concentrations.
• Military sites: Because of the use of firefighting foam during military exercises, military sites are often significant sources of PFAS contamination.

Why PFAS can be hazardous

Because of their extreme persistence in the environment and in the human body, PFAS are also referred to as “Forever Chemicals”. In recent years they have caused increasing concern due to their potential health risks and environmental impacts.

Health effects

Per- and polyfluoroalkyl substances have the ability to accumulate in the human body, which can lead to long-term health problems (bioaccumulation). Some studies have shown that certain perfluorinated chemicals can have adverse effects on human health, including:

• Impairment of the immune system.
• An increased risk of certain types of cancer.
• Adverse effects on the liver.
• Disruption of the hormone system.
• Developmental problems in fetuses and children.

Environmental effects

Extensive research is being conducted to understand the exact effects of per- and polyfluoroalkyl substances on health and the environment. Worldwide, there are efforts to regulate the use and release of these chemicals in order to minimize the risks. Their longevity, their capacity for bioaccumulation and their toxicity are the main reasons for the growing concern and the need for stricter control.

How should PFAS be regulated?

In view of the growing concerns about the environmental and health effects of PFAS, governments and international organizations have initiated measures to control and regulate these chemicals.

Global and national regulatory initiatives

• International agreements: Some per- and polyfluoroalkyl substances, in particular PFOS and PFOA, have been included in international conventions such as the Stockholm Convention on Persistent Organic Pollutants, which led to restrictions and bans on their use.
• EU regulations: The European Union has set specific limit values for perfluorinated chemicals in drinking water and certain products and is working on further rules to control the use and handling of PFAS.
• National legislation: Various countries have taken their own measures, ranging from complete bans on certain perfluorinated chemicals to restrictions on their use in certain products.

Challenges in regulation

• Chemical diversity: The large number of different PFAS compounds makes uniform regulation difficult.
• Scientific uncertainties: Despite extensive research, uncertainties remain regarding the specific effects of individual PFAS compounds, which makes it difficult to define limit values and safety standards.
• Industrial resistance: The broad industrial use leads to conflicts of economic interest, which makes the enforcement of strict regulations difficult.

The regulation of perfluorinated chemicals is a complex and evolving field that challenges both science and policy. You can find more about European chemicals law in our article on the REACH regulation.

Current status of the ECHA's PFAS ban

The European Chemicals Agency (ECHA) has taken significant steps to restrict the use of per- and polyfluorinated alkyl substances in the European Union. These chemicals comprise a family of about 10,000 substances.

Proposal to restrict PFAS

In 2023, the ECHA submitted a proposal to restrict per- and polyfluoroalkyl substances. This proposal was drawn up by five EU member states and submitted to the ECHA: Denmark, Germany, the Netherlands, Norway and Sweden. The aim is comprehensive regulation of these chemicals under the EU REACH regulation.

Public consultation and timeline

The ECHA set up a six-month public consultation phase for this proposal, which began on 22 March 2023 and ended on 25 September 2023. This consultation gave organizations, companies and individuals the opportunity to submit comments and information on the proposal. More than 4,400 organizations, companies and individuals submitted comments and information.

Expected implementation

The EU member states involved are currently advocating an EU-wide ban on PFAS, which is expected to come into force in 2026/2027. This ban aims to restrict the use and release of these chemicals in order to minimize the associated environmental and health risks.

The public consultation initiated by the ECHA and the planned timeline show that this topic is a high priority in EU policy. The final decision and implementation of the restrictions will significantly influence the direction for the future use of perfluorinated chemicals in the EU.

Where is PFAS contamination highest?

Contamination by per- and polyfluorinated alkyl substances is a global problem, with some regions particularly severely affected. A comprehensive investigation in Germany has shown how far-reaching the contamination can be.

Extent of contamination

• Germany: An investigation by NDR, WDR and SZ has identified more than 1,500 sites with PFAS pollution in Germany, including over 300 hotspots with significant contamination.
• Europe: As part of the “Forever Pollution Project”, over 17,000 sites with relevant PFAS pollution were located across Europe, including about 2,000 hotspots that pose considerable health hazards.

Main sources of pollution

• Airports and military sites: Many of these locations are airports and military sites where PFAS-containing firefighting foam was used in the past.
• Wastewater treatment plants and landfills: Wastewater treatment plants and landfills are also affected, as PFAS-containing wastewater and objects collect here.
• Industrial operations: In addition, industries that use per- and polyfluoroalkyl substances or use raw materials contaminated with PFAS contribute to the pollution. Examples are the textile industry, metal finishing, or operations that process waste paper.

Challenges in remediation

In Germany, authorities have completed remediation in less than one percent of all suspected PFAS cases. The Federal Environment Minister described the scale of the damage as alarming and pointed out that remediation is almost impossible for perfluorinated chemicals. Systematic investigations such as those carried out in the USA and France have so far taken place only to a limited extent in Germany. This has led to the identification of several hundred additional potentially contaminated sites.

PFAS regulation in international comparison

USA

The American environmental protection agency (EPA, Environmental Protection Agency) has recommended health advisory limits for PFAS in drinking water, but so far only with mixed success. The FDA regulates the use of approved perfluorinated chemicals in food-contact products but does not set maximum limits for fluoroalkyls in food.

Regulation focused mainly on two chemicals, PFOA and PFOS, with concerns arising about replacing these chemicals with similar ones. On 18 October 2021, EPA Administrator Michael S. Regan announced the agency's PFAS Strategic Roadmap, which outlines a holistic approach to managing PFAS. This roadmap sets deadlines by which the EPA intends to take specific measures and commits to new, bolder policies to protect public health and the environment.

European Union

The EU is planning far-reaching restrictions on the production and use of PFAS. On 7 February 2023, the European Chemicals Agency (ECHA) published a 211-page proposal on PFAS restrictions in accordance with the REACH regulation. This proposal aims to largely eliminate the production and use of fluoroalkyls in Europe, in most applications, above certain very low limit values.

The ECHA plans to generally ban the manufacture, use or placing on the market of per- and polyfluoroalkyl substances, unless they are present in concentrations below certain limit values. The European Commission is not expected to formally deliberate on the proposal until 2025, and the restrictions could come into force from 2026 or 2027.

Asia (focus on China)

In Asia, and in China in particular, there is a clear need for stricter PFAS regulations. A study by Tsinghua University revealed dangerously high PFAS levels in the drinking water of several Chinese cities, underscoring the urgent need to control and reduce PFAS emissions from various industrial sources.

Per- and polyfluoroalkyl substances continue to be produced in China, even though North America and Europe are already phasing out certain perfluorinated chemicals, including PFOA and PFOS. China has taken steps with a draft “New Pollutant Management Action Plan”, which provides for stricter regulations for new chemical registrations, bans and restrictions on harmful chemicals, as well as strict standards for the content of hazardous chemicals in products.

PFAS substitution: material innovation

Work is being done on alternatives to PFAS in several areas. Some examples show that substitution can succeed depending on the application.

• Paper packaging industry: A research team at the US Department of Agriculture (USDA) published a study in 2021 on alternatives to PFAS in paper packaging for food. Waxes or laminations of paper with polymer films such as polyethylene (PE), poly(ethylene-co-vinyl alcohol) and polyethylene terephthalate (PET) were identified as common strategies.
• Tribological applications: One manufacturer has developed an alternative to PTFE-filled sliding materials that requires no PTFE fillers. In combination with PPA, PA66, PPS and PEEK, these new plastic compounds achieve good friction and wear results in various tribological applications.
• Product development: Consulting firms work together with manufacturers to adapt the chemical strategy and to reduce or eliminate the use of problematic chemicals in products. In this way, several leading companies have been able to remove per- and polyfluoroalkyl substances from their products and find viable alternatives.

The role of PFAS in O-ring seals

PFAS are used to manufacture fluoropolymer coatings and products that resist heat, oil, stains, grease and water. These chemicals are widespread in various industrial and consumer products.

In the assembly of mechanical seals, in storage protection and in related products, materials that contain PFAS are often used. These include PTFE, FEP, PFA, FKM, FFKM, FVMQ and FEPM, i.e. fluoropolymers and fluoroelastomers. These materials are usually found in the form of moulded rubber (elastomeric polymer), shaft seals, gaskets, O-rings and other secondary products.

Some companies try to ensure that their elastomers are free of per- and polyfluoroalkyl substances in order to comply with the requirements of authorities such as the EPA and the ECHA. Despite these efforts, the use of certain PFAS compounds in sealing products such as valve packings, pump packings, gaskets and O-rings is essential in various applications and, moreover, has no alternative.

PFAS is a general term for a group of compounds that contain carbon-fluorine bonds. This includes all fluoropolymers and fluoroelastomers such as FKM, FFKM, PTFE and many others.

Essential applications and the lack of alternatives

Some applications of perfluorinated chemicals are to be regarded as essential because of their specific properties and the lack of suitable substitutes. For example, perfluorosulfonated membranes used for ion exchange in chlor-alkali production are essential. These membranes replaced toxic mercury cells and diaphragms made from carcinogenic asbestos. Such applications are indispensable, as there are no established alternatives that offer the required technical function and performance.

The development of alternatives to PFAS represents a major challenge. While alternatives are available for some uses, such as dental floss coated with PTFE, there are as yet no suitable substitutes for other applications, particularly those regarded as indispensable for the safety or functioning of society. In such cases, the continuous research and development of PFAS-free alternatives is decisive.

The chemical resistance of fluoroalkyls is both a blessing and a curse. There are numerous applications for which no suitable alternatives yet exist. At the same time, it must be taken into account that perfluorinated chemicals are indispensable for the urgently needed energy transition and that this will not change in the short term.

The discussion should not focus only on the risks, but should also take into account the essential importance of these chemicals for certain applications and the challenges in finding alternatives. The main goal, however, must be to drive forward the development of material alternatives in order to reduce dependence on persistent and potentially harmful chemicals as far as possible.

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