PFAS – an overview of an emerging chemical of concern and the UK’s approach to monitoring and managing the risks
ECG Bulletin January 2024
Per- and polyfluoroalkyl substances (PFAS) are a group of widely used synthetic substances. They are extremely persistent in the environment and as a result, they have been dubbed the “forever chemicals”. This along with their widespread use means many are now ubiquitous in our environment. Recent monitoring undertaken across England has shown how PFAS are detected in >65% of surface water samples, > 20 % of groundwaters and in all saline and freshwater fish analysed. Despite their widespread use and occurrence very little is known about the toxicity of most PFAS. Many countries are moving towards increased regulation of
some or all PFAS potentially through grouping strategies and/or considering mixture risk assessments.
some or all PFAS potentially through grouping strategies and/or considering mixture risk assessments.
What are PFAS?
Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic substances widely used in many consumer products and industrial applications. They have unique water, oil, heat and stain-resistant properties meaning they have a broad application and can be found in a range of products including cosmetics, paper, coatings, electronics, ammunition, textiles, and artificial turf. Due to their unique and diverse molecular structure, PFAS can play an important and sometimes essential role in improving performance, quality, and longevity of a product. Some of the most documented uses include the production of the fluoropolymer Teflon, the stain- resistant coating Scotchgard[1] and the use in Aqueous Film Forming Foam (AFFF) used as a fire suppressant. AFFFs are made from fluoro- and hydrocarbon surfactants, they are thermally stable and able to form thin films and foam blankets making them effective at extinguishing flammable liquid fires[2], however, due to the amount and nature of the release, they are important sources of PFAS globally. The types of PFAS comprise several different families and sub-families which have been recently defined by The Organisation for Economic Co-operation and Development[3].
Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic substances widely used in many consumer products and industrial applications. They have unique water, oil, heat and stain-resistant properties meaning they have a broad application and can be found in a range of products including cosmetics, paper, coatings, electronics, ammunition, textiles, and artificial turf. Due to their unique and diverse molecular structure, PFAS can play an important and sometimes essential role in improving performance, quality, and longevity of a product. Some of the most documented uses include the production of the fluoropolymer Teflon, the stain- resistant coating Scotchgard[1] and the use in Aqueous Film Forming Foam (AFFF) used as a fire suppressant. AFFFs are made from fluoro- and hydrocarbon surfactants, they are thermally stable and able to form thin films and foam blankets making them effective at extinguishing flammable liquid fires[2], however, due to the amount and nature of the release, they are important sources of PFAS globally. The types of PFAS comprise several different families and sub-families which have been recently defined by The Organisation for Economic Co-operation and Development[3].
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What is the issue?
The same properties of PFAS that are so desired in products and industrial applications also make them extremely resistant to degradation under natural conditions, as a result, they have been dubbed the ‘forever chemicals’ due to their environmental persistence. Two of the most well-studied PFAS are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which were manufactured in significant quantities between 1950 and 2006. |
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Due to their high bioaccumulation and biomagnification potential and associated health impacts, regulatory pressures increased on PFOA and PFOS during the mid-2000s. In response to this pressure, the sector turned to structurally similar replacements, including homologues with fewer fluorinated carbons (short-chain PFAS) or other less well-known PFAS. While most of these replacement PFAS do not bioaccumulate to the same degree, they are just as persistent and often more water soluble and mobile.
As a result, these PFAS are capable of travelling significant distances from their source, and many are now ubiquitous in environmental compartments globally[4].
As a result, these PFAS are capable of travelling significant distances from their source, and many are now ubiquitous in environmental compartments globally[4].
A recent report by the Environment Agency has summarised the current understanding of PFAS from a UK context[5].
Health impacts associated with the exposure of some PFAS include cancer, immune system dysfunction, liver damage, developmental and reproductive harm, and hormone disruption[6,7]. Field studies have shown how many PFAS are able to bioaccumulate and biomagnify, being found at increasing concentrations at higher trophic level. In addition, uptake into plant tissues has been shown to be significant.
While a small number of PFAS have proven impacts on human and environmental health, despite their widespread use, very little is known about the toxicity of thousands of PFAS. This is because most have not been subject to extensive testing, so information about their hazardous properties is unknown. It is also recognised that assessing the hazard for PFAS on a substance-by- substance basis is neither possible nor practical. Despite this uncertainty, many countries are moving towards increased regulation of some or all PFAS. Due to the complexity of the PFAS family, there are growing calls for their management through grouping strategies[8] and/or considering mixture risk assessments[9].
Health impacts associated with the exposure of some PFAS include cancer, immune system dysfunction, liver damage, developmental and reproductive harm, and hormone disruption[6,7]. Field studies have shown how many PFAS are able to bioaccumulate and biomagnify, being found at increasing concentrations at higher trophic level. In addition, uptake into plant tissues has been shown to be significant.
While a small number of PFAS have proven impacts on human and environmental health, despite their widespread use, very little is known about the toxicity of thousands of PFAS. This is because most have not been subject to extensive testing, so information about their hazardous properties is unknown. It is also recognised that assessing the hazard for PFAS on a substance-by- substance basis is neither possible nor practical. Despite this uncertainty, many countries are moving towards increased regulation of some or all PFAS. Due to the complexity of the PFAS family, there are growing calls for their management through grouping strategies[8] and/or considering mixture risk assessments[9].
How PFAS risks are being managed
Due to robust toxicological evidence, PFOA and perfluorohexanesulfonic acid (PFHxS) are already listed under Annex A of the Stockholm Convention and PFOS is listed under Annex B. A fourth PFAS, perfluorononanoic acid (PFNA) is also being increasingly linked to negative health impacts[10]. In the UK, PFOS is a designated priority hazardous substance and classified as a ubiquitous, persistent, bioaccumulative and toxic (uPBTs) compound under the Water Framework Directive (WFD) (2000/60/EC), now superseded by the Water Environment (Water Framework Directive) (England and Wales) Regulations 2017. Ongoing developments in the EU include the submission of a draft Environmental Quality Standard (EQS) dossier for the risk assessment of 24 PFAS[11] which is currently being monitored and reviewed in England, by the Environment Agency and the UK Health & Safety Executive (UK HSE). In October 2021 the UK Drinking Water Inspectorate (DWI) issued guidance and recommended trigger values for water suppliers that cover 47 PFAS. At an international level, both PFOS and PFOA are the subject of an upcoming review in 2023 by the International Agency for Research on Cancer (IARC).
Up until now the management of PFAS has mainly focused on use restrictions. Recently the UK HSE published the PFAS regulatory management option analysis (RMOA) which is a key (non-legally binding) tool to inform policy and support the authorities in their regulatory decision making[12]. This was published alongside the government’s Plan for Water and focused on UK REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) registered PFAS and employed a grouping approach based on structural similarity as an analogue for similarity in hazard profile. The recommendations outlined the need for dossiers under UK REACH to restrict the use and disposal of AFFF where non-PFAS alternatives are available and on other wide dispersive uses such as coatings, cleaning agents, textiles, etc. Other recommendations from the RMOA include “to bring together work on PFAS strategically”, including a review of the UK Fluorinated Greenhouse Gases Regulations (2015) to determine whether additional PFAS registered under UK REACH should be brought within scope.
While these approaches can restrict ongoing PFAS uses and manufacturing, the discharge of PFAS into the environment from legacy sources remains significant. As the awareness of issues has become apparent, the UK has allocated resources to develop, expand and improve capabilities and expertise in PFAS science. This includes specialists in regulation, permitting, monitoring and contaminated land to support bodies including the Environment Agency, Drinking Water Inspectorate, Local Authorities, Food Standards Agency, UK Health and Safety Executive, and Defra.
Due to robust toxicological evidence, PFOA and perfluorohexanesulfonic acid (PFHxS) are already listed under Annex A of the Stockholm Convention and PFOS is listed under Annex B. A fourth PFAS, perfluorononanoic acid (PFNA) is also being increasingly linked to negative health impacts[10]. In the UK, PFOS is a designated priority hazardous substance and classified as a ubiquitous, persistent, bioaccumulative and toxic (uPBTs) compound under the Water Framework Directive (WFD) (2000/60/EC), now superseded by the Water Environment (Water Framework Directive) (England and Wales) Regulations 2017. Ongoing developments in the EU include the submission of a draft Environmental Quality Standard (EQS) dossier for the risk assessment of 24 PFAS[11] which is currently being monitored and reviewed in England, by the Environment Agency and the UK Health & Safety Executive (UK HSE). In October 2021 the UK Drinking Water Inspectorate (DWI) issued guidance and recommended trigger values for water suppliers that cover 47 PFAS. At an international level, both PFOS and PFOA are the subject of an upcoming review in 2023 by the International Agency for Research on Cancer (IARC).
Up until now the management of PFAS has mainly focused on use restrictions. Recently the UK HSE published the PFAS regulatory management option analysis (RMOA) which is a key (non-legally binding) tool to inform policy and support the authorities in their regulatory decision making[12]. This was published alongside the government’s Plan for Water and focused on UK REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) registered PFAS and employed a grouping approach based on structural similarity as an analogue for similarity in hazard profile. The recommendations outlined the need for dossiers under UK REACH to restrict the use and disposal of AFFF where non-PFAS alternatives are available and on other wide dispersive uses such as coatings, cleaning agents, textiles, etc. Other recommendations from the RMOA include “to bring together work on PFAS strategically”, including a review of the UK Fluorinated Greenhouse Gases Regulations (2015) to determine whether additional PFAS registered under UK REACH should be brought within scope.
While these approaches can restrict ongoing PFAS uses and manufacturing, the discharge of PFAS into the environment from legacy sources remains significant. As the awareness of issues has become apparent, the UK has allocated resources to develop, expand and improve capabilities and expertise in PFAS science. This includes specialists in regulation, permitting, monitoring and contaminated land to support bodies including the Environment Agency, Drinking Water Inspectorate, Local Authorities, Food Standards Agency, UK Health and Safety Executive, and Defra.
With thanks to Franziska Türk for the figure.
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How we monitor PFAS in England
The Environment Agency is leading a number of investigations, R&D projects and innovative monitoring programmes to better understand the occurrence and behaviour of PFAS in different environmental compartments. This involves the research and development of analytical capabilities that are now delivering a number of internationally significant programmes. |
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Currently 43 individual PFAS are being routinely monitored by the Environment Agency in surface and groundwater. To complement this, investigations that include PFAS Total Oxidisable Precursor Assay analysis (PFAS Top assays) and ultra-short chain PFAS such as trifluoroacetic acid (TFA) are being undertaken to better understand the environmental PFAS burden. These monitoring campaigns are demonstrating how perfluorobutanoic acid (PFBA), perfluoropentanoic Acid (PFPeA), perfluoroheptanoic acid (PFHpA), PFOA, perfluorobutanesulfonic acid (PFBS), and PFOS are detected in >65% of surface water samples and PFBA, PFOA and 6:2 Fluorotelomer sulfonic acid (6:2 FTS) are detected in >20% of our groundwaters.
Across the UK there are also number of monitoring programmes that look for PFAS in biota including fish, otters, predatory birds, and marine mammals. As with similar monitoring campaigns globally[13,14], these data are demonstrating the ubiquity of PFAS in the environment. Freshwater fish monitored by the Environment Agency demonstrate how longer chain perfluoroalkyl carboxylic acids (PFCA); perfluorodecanoate (PFDcA), perfluoroundecanoate (PFUnA), perfluorododecanoate (PFDoDA), perfluorotridecanoate (PFTrDA), perfluorotetradecanoate (PFTeDA) and perfluoroalkyl sulfonic acids (PFSA); PFOS, PFHxS and the perfluoroalkane sulfonamides (FASA); and PFBA are detected in all samples.
The Environment Agency is also working closely with Water companies to investigate PFAS through the Chemicals Investigation Programmes and undertake targeted monitoring for PFAS in effluents, receiving waters, and sewage sludges. In an attempt to limit emissions, UK regulators are currently reviewing a number of permitted discharges to water from high-risk sources such as airports, PFAS manufacturing facilities and Waste Water Treatment Works (WwTW).
Across the UK there are also number of monitoring programmes that look for PFAS in biota including fish, otters, predatory birds, and marine mammals. As with similar monitoring campaigns globally[13,14], these data are demonstrating the ubiquity of PFAS in the environment. Freshwater fish monitored by the Environment Agency demonstrate how longer chain perfluoroalkyl carboxylic acids (PFCA); perfluorodecanoate (PFDcA), perfluoroundecanoate (PFUnA), perfluorododecanoate (PFDoDA), perfluorotridecanoate (PFTrDA), perfluorotetradecanoate (PFTeDA) and perfluoroalkyl sulfonic acids (PFSA); PFOS, PFHxS and the perfluoroalkane sulfonamides (FASA); and PFBA are detected in all samples.
The Environment Agency is also working closely with Water companies to investigate PFAS through the Chemicals Investigation Programmes and undertake targeted monitoring for PFAS in effluents, receiving waters, and sewage sludges. In an attempt to limit emissions, UK regulators are currently reviewing a number of permitted discharges to water from high-risk sources such as airports, PFAS manufacturing facilities and Waste Water Treatment Works (WwTW).
Analytical challenges
Measuring PFAS is difficult and there are numerous methods and approaches available. Fully quantitative analysis using mass spectrometry is one of the most applied, however, due to the chemical diversity of the group and corporate secrecy surrounding their manufacturing, formulation and structure; analytical standards are only available for around 50 substances. While these analyses have demonstrated the occurrence of PFSAs and PFCAs in many publications, the presence of less stable precursors and intermediates are less understood. These precursors can undergo abiotic or biotic transformation to the more stable PFSAs and PFCAs and are likely to have different physical, chemical and toxicological properties from their breakdown products[15].
Understanding the PFAS’ true burden of a sample often requires different methodologies for sample collection, preparation, and analysis. While techniques such as fluorine nuclear magnetic resonance, suspect screening and nontarget analysis offer a broader insight into unknown PFAS, there is an ongoing need for better suspect lists and new identification tools to broaden our analytical scope.
Measuring PFAS is difficult and there are numerous methods and approaches available. Fully quantitative analysis using mass spectrometry is one of the most applied, however, due to the chemical diversity of the group and corporate secrecy surrounding their manufacturing, formulation and structure; analytical standards are only available for around 50 substances. While these analyses have demonstrated the occurrence of PFSAs and PFCAs in many publications, the presence of less stable precursors and intermediates are less understood. These precursors can undergo abiotic or biotic transformation to the more stable PFSAs and PFCAs and are likely to have different physical, chemical and toxicological properties from their breakdown products[15].
Understanding the PFAS’ true burden of a sample often requires different methodologies for sample collection, preparation, and analysis. While techniques such as fluorine nuclear magnetic resonance, suspect screening and nontarget analysis offer a broader insight into unknown PFAS, there is an ongoing need for better suspect lists and new identification tools to broaden our analytical scope.
Environmental challenges
PFAS pollution is a critical worldwide issue, and their toxic and persistent properties are present significant and tangible risks to health of humans and wildlife. From a risk management perspective, one of the biggest challenges we have stems from how little we know about the majority of PFAS. Across England, recent risk screening work reviewing potential source sites has identified over 20,000 locations across England. Addressing the issues will often require collaboration between multiple regulators and stakeholders who may lack the resource and expertise.
PFAS are currently one of the most significant environmental pollutants globally, and the Nordic Council of Ministers estimates that the direct healthcare costs from exposure to PFAS in Europe alone are €52-84 billion annually[16]. Once released into the environment PFAS are extremely difficult to remove and remediate. The societal cost is often shouldered by governments typically forced to fund the clean-up of pollution and individuals who suffer from health consequences[17].
PFAS pollution is a critical worldwide issue, and their toxic and persistent properties are present significant and tangible risks to health of humans and wildlife. From a risk management perspective, one of the biggest challenges we have stems from how little we know about the majority of PFAS. Across England, recent risk screening work reviewing potential source sites has identified over 20,000 locations across England. Addressing the issues will often require collaboration between multiple regulators and stakeholders who may lack the resource and expertise.
PFAS are currently one of the most significant environmental pollutants globally, and the Nordic Council of Ministers estimates that the direct healthcare costs from exposure to PFAS in Europe alone are €52-84 billion annually[16]. Once released into the environment PFAS are extremely difficult to remove and remediate. The societal cost is often shouldered by governments typically forced to fund the clean-up of pollution and individuals who suffer from health consequences[17].
In summary
Even with tighter PFAS regulation, the legacy of these "forever chemicals" will be around for decades to come. To implement effective management regimes better insights into the contributions from different polluters is needed. While so much is still unknown about the fate, transport, toxicity and environmental burden of thousands of PFAS, as a society we need to manage these uncertainties. While measures and actions need to be underpinned by the best available science, the lack of information should not prevent justifiable action being taken.
Even with tighter PFAS regulation, the legacy of these "forever chemicals" will be around for decades to come. To implement effective management regimes better insights into the contributions from different polluters is needed. While so much is still unknown about the fate, transport, toxicity and environmental burden of thousands of PFAS, as a society we need to manage these uncertainties. While measures and actions need to be underpinned by the best available science, the lack of information should not prevent justifiable action being taken.
References
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