Document v1RJ2y8YoNv04kbqdwQjd00bZ

Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. icle is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Environmental Science Processes & Impacts CRITICAL REVIEW ROYAL SOCIETY OF CHEMISTRY View Article Online View Journal I View Issue Check for updates Cite this: Environ. Sci.: Processes Impacts, 2019, 21, 1803 Received 8th April 2019 Accepted 27th May 2019 DOI: 10.1039/c9em00163h rsc.li/espi The concept of essential use for determining when uses of PFASs can be phased out Ian T. Cousins,er a Gretta Goldenman,b Dorte Herzke,` Rainer Lohmann, Mark Miller,e Carla A. Ng,ef Sharyle Patton,g Martin Scheringer,Oh Xenia Trier,' Lena Vierke,i Zhanyun Wange k and Jamie C. DeWite Because of the extreme persistence of per- and polyfluoroalkyl substances (PFASs) and their associated risks, the Madrid Statement argues for stopping their use where they are deemed not essential or when safer alternatives exist. To determine when uses of PFASs have an essential function in modern society, and when they do not, is not an easy task. Here, we: (1) develop the concept of "essential use" based on an existing approach described in the Montreal Protocol, (2) apply the concept to various uses of PFASs to determine the feasibility of elimination or substitution of PFASs in each use category, and (3) outline the challenges for phasing out uses of PFASs in society. In brief, we developed three distinct categories to describe the different levels of essentiality of individual uses. A phase-out of many uses of PFASs can be implemented because they are not necessary for the betterment of society in terms of health and safety, or because functional alternatives are currently available that can be substituted into these products or applications. Some specific uses of PFASs would be considered essential because they provide for vital functions and are currently without established alternatives. However, this essentiality should not be considered as permanent; rather, constant efforts are needed to search for alternatives. We provide a description of several ongoing uses of PFASs and discuss whether these uses are essential or non-essential according to the three essentiality categories. It is not possible to describe each use case of PFASs in detail in this single article. For follow-up work, we suggest further refining the assessment of the use cases of PFASs covered here, where necessary, and expanding the application of this concept to all other uses of PFASs. The concept of essential use can also be applied in the management of other chemicals, or groups of chemicals, of concern. Environmental significance PFASs are manmade organic contaminants that can be found everywhere in the global environment, largely as a result of their high persistence and wide use. Based on concerns regarding their high persistence and other hazardous properties, it has been argued that the production and use of PFASs should be limited to essential uses only. In this paper, we translate the concept of "essential uses" or "essentiality" into three criteria to determine when uses of PFASs are essential, or not, and demonstrate how the criteria can be applied to different use cases of PFASs. This approach can inform and encourage manufacturers, retailers and end users to consider phasing out and substituting uses of PFASs. Thus, the uses and related emissions of PFASs can be systematically limited and the long-term harm to human health and the environment can be avoided. 'Department of Environmental Science and Analytical Chemist!), (ACES), Stockholm University, SE-10691, Sweden. E-mail: aces.su.se 'Milieu, Brussels, Belgium WILLI, Norwegian Institute for Air Research, Tromso, Norway "Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA `National Institute of Environmental Health Sciences, U.S. Public Health Service, Research Triangle Park, NC, USA fDepartment of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA 'Health and Environment Program Commonweal, CA, USA 'Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zurich, Switzerland 'DTU Technical University of Denmark, Copenhagen, Denmark 'German Environment Agency (UBA), Dessau-Rofilau, Germany 'Chair of Ecological Systems Design, Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland `East Carolina University, Greenville, NC, USA t Currently working at the European Environment Agency, Copenhagen. This journal is The Royal Society of Chemistry 2019 Environ. Sd.. Processes Impacts, 2019, 21, 1803-1815 1 1803 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Environmental Science: Processes & Impacts View Article Online Critical Review Introduction Per- and polyuoroalkyl substances (PFASs) are a group of more than 4700 substances1 that have been produced since the 1940s and used in a broad range of consumer products and industrial applications.2 The multiple uses of PFASs have been wellillustrated by the FluoroCouncil.3 PFASs can be broadly divided into low molecular weight and high molecular weight (polymeric) substances. The polymeric PFASs can be further subdivided into side-chain uorinated polymers, uoropolymers and peruoropolyethers.2 The review of Buck et al.2 and the FluoroCouncil website3 should be consulted for a detailed description of the structures, classes and uses of low and high molecular weight PFASs as that background will not be provided here. Since 2000 there have been a number of voluntary industry phase-outs and regulatory actions to cease the manufacture and use of long-chain peruoroalkyl acids (PFAAs; dened as including peruoroalkane sulfonic acids (PFSAs) with peruoroalkyl chains containing 6 carbons or more, and peruoroalkyl carboxylic acids (PFCAs) with peruoroalkyl chains containing 7 carbons or more) and their precursors, which can transform in the environment or within organisms to longchain PFAAs. The most common replacements for the above dened long-chain PFAS chemistries are shorter-chain PFASs, e.g. PFAAs with fewer uorinated carbons than long-chain PFAAs, and peruoroether-based substances (PFASs with peruoroalkyl segments joined by ether linkages).4 Although some of these replacement PFASs are less bioaccumulative, they are all similarly highly persistent in the environment as their predecessors.5,6 PFAAs which are considered short-chain and non-bioaccumulative may also lead to high internal concentrations if people are continuously exposed to high levels. Moreover, short-chain PFAAs, such as peruorobutanoic acid (PFBA) and PFHxA, tend to be highly mobile and to move readily into ground and surface waters once released to the environment where they can reside for decades to centuries.7-10 As a result of their high environmental persistence, widespread use and release of any PFAS, even polymeric PFASs,11 will lead to irreversible global contamination and exposure of wildlife and humans, with currently unknown consequences.12-14 Based on concerns regarding the high persistence of PFASs and the lack of knowledge on chemical structures, properties, uses, and toxicological proles of most PFASs currently in use, it has been argued by more than 200 scientists in the Madrid Statement that the production and use of PFASs should be limited.12 Indeed, in the textile sector, some brand names and retailers have recognized the problems associated with PFASs and have already taken signicant steps to phase out all uses of PFASs in their consumer products.15-18 It is neither practical nor reasonable to ban all uses of PFASs in one step. Some specic applications may serve a critical role for which alternatives currently do not exist. However, if some uses of PFASs are found not to be essential to health, safety or the functioning of today's society, they could be eliminated without having to rst nd functional alternatives providing an adequate function and performance. Elimination of nonessential uses of PFASs could form a starting point for a process that leads to a global phase-out (e.g. through the Stockholm Convention on Persistent Organic Pollutants). To critically evaluate the idea that PFASs are essential in modern society, the essentiality of PFASs should be carefully tested against the available evidence for each of their uses. Given the thousands of PFASs on the market and their many uses, this is a formidable but necessary task. Before proceeding in this task, a denition of essentiality, or essential use, is needed. If PFASs are considered non-essential in a given use, then a phase-out of PFASs from that use can be implemented. The aims and structure of this paper are therefore to: (1) dene the concept of essential use or essentiality, (2) apply the concept to various use categories of PFASs to determine the feasibility of limiting use, as showcases of the concept, and (3) outline the remaining challenges for phasing out uses of PFASs in society and provide recommendations for further work. It is not our intention to conduct conclusive assessments for our selected use cases of PFASs on the individual use level. Follow-up work may be needed to cover each use case in more detail, where necessary, and to expand the application of the concept to all other uses of PFASs. The concept of `essential use' This approach is based on the example of the Montreal Protocol, which phased out the use of ozone-depleting chlorouorocarbons except for certain `essential' uses, and which dened the concept of `essential use' in Decision IV/25.19 The two elements of an essential use are that a use is "necessary for health, safety or is critical for the functioning of society" and that "there are no available technically and economically feasible alternatives". To identify uses of PFASs that are nonessential, we combine the denition of essentiality with several categories of PFAS uses. Overall, this leads to the three categories summarized in Table 1. For uses in category 1 ("non-essential" uses), a phase-out via a ban or restriction of PFASs can be prepared because these uses are not necessary for the betterment of society in terms of health, safety and functioning. The technical function of the PFAS (if it has one) in the use case could be considered "nice to have" (e.g. non-stick frying pans) but it is not essential. In many cases the "nice to have" function can be fullled through substitution with uorine-free alternatives. Even where there are no alternatives to PFAS for providing the "nice to have" function, the use case can be banned or phased out because it is not essential. Uses in category 2 ("substitutable" uses) fulll important functions but are assessed to be non-essential because there are alternatives available that can be substituted into these products or applications and provide the necessary technical function and performance. It may be needed to make the alternatives more well-known and more easily available, but there is no fundamental obstacle to removing PFASs from these uses. Upon increased market uptake, the costs can be expected to decrease.20,21 1804 | Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 This journal is The Royal Society of Chemistry 2019 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Critical Review View Article Online Environmental Science: Processes & Impacts Table 1 Three essentiality categories to aid the phase out of non-essential uses of chemicals of concern, exemplified with PFAS uses Category Denition PFAS examples (1) "Non-essential" (2) "Substitutable" (3) "Essential" Uses that are not essential for health and safety, and the functioning of society. The use of substances is driven primarily by market opportunity Uses that have come to be regarded as essential because they perform important functions, but where alternatives to the substances have now been developed that have equivalent functionality and adequate performance, which makes those uses of the substances no longer essential Uses considered essential because they are necessary for health or safety or other highly important purposes and for which alternatives are not yet establisheda Dental oss, water-repellent surfer shorts, ski waxes Most uses of AFFFs, certain water-resistant textiles Certain medical devices, occupational protective clothing a This essentiality should not be considered permanent; rather, a constant pressure is needed to search for alternatives in order to move these uses into category 2 above. Uses in category 3 ("essential" uses) are considered necessary and currently have no established alternatives to PFASs that provide the necessary technical function and performance. Innovative research and development may be needed to identify chemical or engineering alternatives and to make them technically and economically feasible. By identifying these opportunities, strong market incentives will be created for industry to develop such alternatives. In support of this approach research and innovation funding could be made available specically for this purpose, and to support start-up companies that intend to develop and market new alternatives. Implementation of this conceptual framework could give rise to `grey zones' where it may not be straightforward to assign a use to a particular category. For example, a grey zone might appear between categories 1 and 2 because some uses of PFASs may be considered as nice-to-have by some (stain-proof and waterproof outdoor jacket for everyday use) and as necessary by others. Similarly, a grey zone could turn up between categories 2 and 3 because the availability and performance of alternatives is being debated (e.g. AFFFs used by the military for extinguishing fuel res). In order to avoid/minimize such `grey zones' in the implementation of this conceptual framework, clear criteria and relevant processes need to be pre-dened. This would require follow-up work that is beyond the scope of the present paper. Technical performance standards may play a role in dening whether the use of PFASs is or is not considered "essential" in certain cases. Technical performance standards are detailed specications concerning how a product should perform in certain circumstances and are oen voluntary. However, they may be used to dene whether a product is of sufficient quality to be placed on the market or to be purchased through public procurement. For example, some European Union productrelated legislation sets so-called "essential requirements" for certain products and then delegates the task of dening how to meet those requirements to European standard-setting bodies, such as the European Committee for Standardization (CEN). The International Standardization Organization (ISO) and national bodies such as the German Technischer Uberwachungsverein (TUV) may also set certication requirements that may be important in the design of the product performance, and how to demonstrate it. The case studies below provide several examples of how technical standards may affect whether a use of PFASs is "essential" or not. Case studies of uses of PFASs Below we provide descriptions of several ongoing uses of PFASs. We discuss whether the uses of PFASs are essential or nonessential based on the categorization in Table 1. Personal care products and cosmetics. PFASs have been found in a range of different cosmetics and personal care products including hair products, powders, sun blocks, and skin creams.22 The uorinated ingredients in some of the products that have been chemically analyzed are listed in Schultes et al.22 and include a range of uorosurfactants and in some cases the uoropolymer, polytetrauoroethylene (PTFE). The use of certain PFASs in these products may lead to direct human exposure and potential health effects following dermal or oral uptake. It is not clear whether any technical function provided by the PFASs is truly necessary. Aer a recent campaign by a Swedish NGO publicizing the presence of PFASs in certain cosmetics, it was relatively easy for several major retailers and brands of cosmetics to quickly announce phase outs of PFASs, for example, L'Oreal, H&M, Lumene, The Body Shop, Isadora, and Kicks.23 If PFASs in these products were needed for their technical function (possibly liquid repellency and/or to aid spreading over and into the skin) then drop-in alternatives appear to have been readily available given the rapid phase out by retailers. The use of PFASs in personal care products falls under category 1 in Table 1. Ski waxes. Whereas most skiers use hydrocarbon-based glide waxes, uorinated glide waxes are also available, though much This journal is The Royal Society of Chemistry 2019 Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 | 1805 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Environmental Science: Processes & Impacts View Article Online Critical Review more expensive. The uorinated waxes are favored by competitive skiers because they are highly water repellent and result in better glide compared to hydrocarbon-based waxes. The PFASs used in uorinated ski waxes are diblock semiuorinated nalkanes (SFAs) mixed with normal paraffins.2 PFCAs, including peruorooctanoic acid (PFOA), have also been found in uorinated ski waxes provided as solids or in powder form.24 The presence of SFAs in snow and soil samples from a ski area in Sweden was recently demonstrated25 and professional ski wax technicians working for the Swedish national cross-country ski team were shown to be highly exposed to PFCAs.26 From July 2020 onwards, PFOA and related substances (e.g. substances which might form PFOA in the environment) will be banned in all products sold in the EU, including ski waxes, due to its recent addition to the REACH Annex XVII list of restricted substances (entry 68). No essential use of PFASs in ski waxes was found in the restriction process and this use category is therefore clearly non-essential. Functioning hydrocarbon-based ski waxes were in use before the uorinated waxes were introduced. The development of uorinated waxes was driven by their exceptional technical performance and market opportunity. Fluorinated waxes provide a "nice to have" function that is not essential, and therefore this use case falls under category 1 in Table 1. However, European ski teams are continuing to use uorinated waxes. The exception is Norway which in Oct 2018 announced that it has banned the use of uorinated ski waxes in U16 categories in national competitions.27 Fire-ghting foams. Class B reghting foams are formulated to extinguish res of ammable liquids, such as liquid hydrocarbon fuels. Those currently available are either; (i) aqueous lm-forming foams (AFFF), uoroprotein foams (FP), or lm-forming uoroprotein foams (FFFP), all of which contain uorosurfactants (i.e. they contain PFASs) and (ii) uorine-free class B foams (F3) using proprietary mixtures of hydrocarbon or silicone surfactants.28 PFAS-containing AFFFs historically contained long-chain PFAAs (and their precur- sors),29 but since 201530 the foam manufacturers have elimi- nated long-chain PFAAs (and their precursors) from their products. Current uorotelomer-based AFFF formulations contain uorosurfactants that may transform to short-chain PFAAs (primarily PFHxA and shorter-chain PFAAs) in the environment, which are thought to be less bioaccumulative and less toxic than their longer-chain predecessors. However, short- chain PFAAs are extremely persistent and mobile, and if clean-up of soil or water is later needed, it will be extremely expensive and time-consuming, if at all possible.13,31 Fluorine-free class B foams were rst developed in the early 2000s by the 3M Company and since then many other compa- nies have marketed uorine-free class B foams.28 Many of the currently available uorine-free foams meet the standard reghting performance certications applicable to PFAScontaining AFFF and related foams.28 Though some debate continues concerning whether PFAS- containing foams remain necessary for certain scenarios, e.g., res at reneries or involving very large fuel tanks, in recent years, a number of commercial airports, chemical industry facilities, oil and gas platforms, re brigades and some national defense forces around the world have switched to using uorine-free foams based on demonstrated operational performance in extinguishing fuel res. However, US military forces are currently prevented from switching to uorine-free foams because the applicable technical standard MIL-F24385F(SH) - though revised in 2017 to reduce PFOA and PFOS in AFFFs - still requires uorinated chemistry in addition to setting a performance-based requirement. Note that in October 2018, the US Congress enacted a bill32 permitting civilian airports across the US to use non-uorinated alternatives. Hydrocarbon-based foams have been shown to be biodegradable with only localized, short-term problems associated with their release during extinguishing res or spillages. The silicone-based foams may contain low residual amounts of cyclic siloxanes (e.g. decamethylcyclopentasiloxane or D5), which have been judged to be persistent and bioaccumulative.33 Both D5 and D4 (octamethylcyclotetrasiloxane) are listed as Substances of Very High Concern under REACH, primarily because of their vPvB (very persistent, very bioaccumulative) properties.34 In summary, the uorine-free foams that have been developed and improved since the early 2000s are promising from an operational perspective35-37 and also from an environmental and human health perspective. Some military maintain that only PFAS-containing AFFF can provide the necessary performance requirements, particularly in the case of large fuel res. Because of ongoing debate, this use category therefore currently falls under category 2 or 3 in Table 1. Durable water and stain repellency in textiles. Liquid repellency in textile products can range from an optional "nice-to-have" property in leisure jeans to an essential protection needed in occupational protective clothing.38 The textile sector oen refers to these chemistries as durable water repellents (DWRs), but the leading market technology repels more than just water. Since their introduction in the 1950s, the highest level of repellency for both oil/stain and water has been achieved with side-chain uorinated polymers. Substitution to `short-chain' side-chain uorinated polymers (typically C6 or C4 peruoroalkyl chains) has taken place in recent years. However, there is concern regarding the extreme persistence and lack of human health data for short-chain PFAAs. A variety of new non-uorinated DWR alternatives has been developed to create repellent textile surfaces, with a variety of polymer architectures, including linear polyurethanes, hyperbranched polymers and nanoparticles.38 The functional moieties in terms of liquid repellency consist of either saturated alkyl chains (i.e. hydrocarbons) or polydimethylsiloxane (PDMS) chemistry (i.e. silicone polymers).38 Although hazards associated with non-uorinated DWRs are not yet fully understood, the development of biodegradable alternatives is an important step. Similar to the silicone-based surfactants used in reghting foams, the silicone-based DWRs may contain residual amounts of persistent cyclic siloxanes (e.g. D4 and D5). Non-uorinated DWRs have been shown to provide high water repellency equal to short-chain uorinated polymers and are suitable substitutes for consumer outdoor clothing.39 1806 | Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 This journal is The Royal Society of Chemistry 2019 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Critical Review View Article Online Environmental Science: Processes & Impacts Indeed, a number of leading brands already provide waterrepellent outdoor jackets marketed as e.g. "uorine-free". However, in the case of both non-polar and polar liquids with very low surface tension (such as olive oil or gastric uid), so far only short-chain uorinated polymers have been shown to provide effective protection.40 Such protection may be important in certain occupational settings where a specied level of performance is required. Medical textiles are an example of where technical standards to protect human lives require a certain performance that may be difficult to meet without the use of PFASs. The European standard EN 13795 denes how the essential requirements set forth in the EU Medical Devices Directive (93/42/EEC)41 should be met with respect to surgical gowns, drapes and clean air suits. Along with setting performance requirements aimed at preventing the transmission of infectious agents between patients and medical staff, EN 13795 also stipulates the test methods for evaluating whether the performance requirement is met. The test method EN 2081142 - resistance to liquid penetration - measures the pressure at which water will pene- trate the fabric and is used to determine whether the fabric will provide sufficient protection against contamination from penetration by e.g. bodily uids. Current non-uorinated DWRs may not provide sufficient liquid repellency for non-polar bodily uids with low surface tension. An alternative is to use surgical gowns coated with a plastic laminate, which offer sufficient protection against biological uids containing potentially harmful viruses and bacteria but may not be sufficiently breathable for longer operations. Similarly, performance standards set by the US National Fire Prevention Association for protective clothing for reghters and other emergency responders for water repellency, oil/stain repellency and breathability are currently not possible to meet without uorinated chemistry. Other types of occupational clothing, e.g. in the oil and gas sector, may require a similar combination of water and oil/stain repellency as well as breathability. At least for now, these uses of PFASs may be considered essential and are, therefore, in category 3, until effective and safer alternatives are available. In summary, non-uorinated DWRs are available that provide good water repellency (and certain stain repellency) meeting consumer requirements and expectations for most outdoor apparel, casual wear, and business attire (category 2). In some cases, the use of uorinated DWRs in textiles is "nice to have" (e.g. water-repellent surfer shorts), but is non-essential and falls under category 1. Only a few uses of PFAS in textiles, e.g. the occupational protective clothing market, where repel- lency of a wider range of liquids as well as breathability are necessary, fall under category 3 in Table 1. In those cases, innovative solutions are needed to provide non-uorinated alternatives. Food contact materials. Food contact materials (FCMs) cover a range of materials that at some stage come into contact with food. This includes (industrial) food-production equipment and machinery, food packaging, and kitchen utensils like non-stick forms and pans. Growing consumer concern over environ- mental and health impacts of plastic packaging has led to an increasing market pressure for alternative packaging, including paper.43 This may result in increasing exposures to PFAScontaining paper-based materials. The types of uorochemistry used to protect paper and board have changed over time.44 Initially, long-chain PFASs were used and were phased out in the 2000s.44 Current uorinated paper and board products are largely based on "short-chain" uorotelomer-based polymeric products, which are side-chain uorinated polymers containing peruoroalkyl side chains, typically with six peruorinated carbons,44 and poly- and peruoropolyethers.45-48 Despite reassurances by the chemical manufacturing industry that short-chain uorinated products are safe, there is concern that PFASs will migrate into food and cause harm to human health.44 Non-uorinated alternatives have subsequently entered the market in recent years. For example, COOP Denmark A/S, a Danish consumer goods retailer, has succeeded in completely removing PFASs from all its products since September 2014.49 Although the current polymer chemistry used in paper and board in food contact materials is similar to that used in textiles, paper and board are oen made for single use, whereas textiles (e.g. outdoor jackets) need to be durable over the lifetime of a garment. However, some paper and board products need to provide repellency to oil for weeks to months (e.g. butter wrappers), whereas others (e.g. fast-food wrappers) only require oil repellency for a matter of minutes. The substitution strategies for paper and board are therefore different than for DWRs in textiles given the difference in materials and performance requirements, and may even be different among food contact applications. There are generally two types of barriers against grease or fat for paper and board, a physical or a chemical barrier.44 A physical barrier preventing penetration of a liquid into the paper may be sufficient in certain types of single use applications. The chemical barrier, which is the approach used in uorinated products, repels the grease in the food due to the very weak physico-chemical interaction between grease and paper surface. Two of the most common types of paper that provide a physical barrier against grease are Natural Greaseproof paper50 and vegetable parchment,51 providing a dense cellulose structure that prevents the grease from soaking into the paper. There are also various non-uorinated chemical barriers that can provide similar repellency to grease as uorinated repellents, including hydrocarbon- and silicone-based alternatives.52 A third alternative is to add physical barriers such as aluminum or plastic coatings to the paper to provide protection.53 In food production, PFASs are mainly used as non-stick uoropolymer (e.g. PTFE) coatings of (metal) surfaces to lower friction (which protects the equipment from abrasion), to minimize adhesion (which allows better cleaning of surfaces), as non-stick- or heat- and acid-resistant uoroelastomer membranes on conveyor belts, and as lubricant oils and greases in machinery.54-57 Many of the same uses exist in household kitchen utensils and appliances. These uses are described in This journal is The Royal Society of Chemistry 2019 Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 | 1807 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Environmental Science: Processes & Impacts View Article Online Critical Review industry patents and commercial materials,54 but the levels and types of PFASs have been studied only to a limited extent.58,59 Non-stick kitchenware is normally produced by either spraying or rolling layers of PTFE onto the surface of the kitchenware. One could argue that the non-stick is a "nice to have" function rather than an essential function given that it is possible to cook food without the non-stick functionality. If the non-stick coating is considered an essential function in a modern society, then other possible non-stick coatings are available, including: enamelled iron-, ceramic-, and anodized aluminium coatings.60 In summary, non-uorinated alternatives have been historically available for all applications of paper-and-board food packaging and the use of uorinated protective coatings has never been essential (category 1). For example, COOP, a major grocery retailer in Denmark, has found alternatives for all products that previously used PFASs.49,61 For non-stick cookware there are also non-uorinated non-stick alternatives which work well in households and this is also not an essential function (category 1). In the food production industry non-uorinated conveyor belts, lubricants and greases exist, but it is not clear currently whether functional alternatives to uoropolymer protection against abrasion exist (categories 2 or 3). Medical devices. Another use of uoropolymers is as coatings in catheters, stents and needles to reduce friction and improve clot resistance and to provide protein-resistance in lters, tubing, O-rings, seals, and gaskets used in kidney dialysis machines and immunodiagnostic instruments.3,54,62 The safety evaluation of these devices for use in humans was discussed by Henry et al. (2018).63 Aer review, multiple regulatory agencies have concluded that the use of PFASs in these products, including in devices implanted into patients' bodies, does not pose an appreciable risk because the uoropolymers are not bioavailable.63-65 It is however unclear whether impurities of uoropolymer processing aids such as PFOA and HFPO-DA were included in the regulatory reviews. In summary, the inclusion of uoropolymers into medical devices confers several benets and does not appear to pose substantial health risks to those who are exposed to these devices through procedures or who have received implants. However, the production and disposal of these devices will continue to lead to the release of PFASs into the environment unless steps are taken to eliminate environmental releases. The use of PFASs in medical devices falls under categories 1-3 in Table 1 (depending on specic use). However, due to limited information in the public domain, it is currently unclear if all medical devices need uoropolymers or only certain types of medical devices need uoropolymers. Pharmaceuticals. There are a wide range of uorinecontaining pharmaceuticals.66 Since the rst uorinecontaining drug was approved by the U.S. Food and Drug Administration (FDA) in 1955, nearly 150 uorinated drugs have reached the market and about 30% of newly approved drugs contain uorine constituents including uoroalkyl groups (a smaller subset can be dened as PFASs). According to Zhou et al. (2016),66 uorinated drugs encompass all therapeutic areas, are structurally diverse, and are among the mostprescribed and/or protable in the U.S. pharmaceutical market. Fluorination of pharmacological agents is oen used to enhance their pharmacological effectiveness, increase their biological half-life, and improve their bioabsorption.66 Some agents are analogous to the long-chain PFASs, such as several types of articial blood formulations and drugs for the lungs of prematurely born children (for example: peruorooctyl bromide, an eight-carbon bromine-substituted PFAS67). However, most uorine-containing pharmaceuticals have only one or two uorine atoms. A smaller number of drugs contain one or two triuoromethyl groups (-CF3), or the peruoroalkyl moiety CnF2n+1 as dened by Buck et al. (2011).2 As these agents become more widely produced, prescribed, and used, disposal of these uorinated drugs (e.g. through municipal wastewaters) is likely to lead to increasing environmental releases of various PFASs. A transformation product of nearly all of the anesthetics is triuoroacetic acid (TFA or CF3COOH), which can arise from several metabolic or atmospheric degradation pathways68 and has been a cause of environmental concern.69-71 In summary, the addition of 1-3 uorine atoms or triuoromethyl groups to various pharmaceutical agents has improved their efficacy, half-lives, and bioabsorption and does not appear to pose substantial health risks to those who take them, relative to analogous non-uorinated drugs. However, their production and disposal will continue to lead to the release of PFASs into the environment unless steps are taken to eliminate environmental releases. Releases of human metabolic excretion products may pose an additional environmental concern (contamination of water and greenhouse gases) as these drugs become more widely used. The uses of -CR2F, -CRF2, and -CF3 groups in pharmaceuticals should not be evaluated for essentiality as a single group, as specic applications will likely fall under either categories 2 or 3 in Table 1; there are functional non-PFAS alternatives for some pharma- ceutical applications, whereas for other uses the pharmaceuti- cals have life-saving functions. Laboratory supplies, equipment and instrumentation. PFAS- containing products, in particular uoropolymers, are also ubiquitous in laboratories, laboratory supplies and analytical instrumentation. Initially this caused major concerns regarding PFAS contamination of environmental and biolog- ical samples during PFAS analysis and maintaining quality control in PFAS analysis.72,73 The PFASs are used because they have high resistance to chemicals and heat, weak interaction with other substances and low permeability, which prevent chemicals/analytes from being adsorbed to the surface and absorbed into the material. In the laboratory, there are easily identiable uoropolymer (e.g. PTFE) and uoroelastomer-based products (e.g. Viton). Examples include the use of uoropolymer-based vials, caps and tape, and uoropolymers in the solvent degassers of liquid chromatography (LC) instruments. Non-PFAS replacements may be available, depending on the purpose. Personal protec- tive equipment can also contain PFASs, including protective gloves and protective mist/anti-fog coatings of glass (e.g. PFPE). These applications can in general be substituted without major 1808 | Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 This journal is The Royal Society of Chemistry 2019 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Critical Review View Article Online Environmental Science: Processes & Impacts loss of functionality or performance; recommendations for PFAS-free alternatives are oen provided as part of guidance to prevent cross-contamination when sampling or analyzing environmental matrices for PFAS.74-76 As part of eld or laboratory collection of particles of different sizes, some lters are made of or are coated with PFASs to minimize sorption of compounds to the lter itself, such as glass ber lters, or ultraltration lters. As an alternative plastic lters/vials with a low solid surface energy can be used (e.g. polypropylene (PP), polytetramethylene oxide (PTME) and polyamide (nylon)).46,77 More difficult to replace are uoropolymer and uoroelastomer seals (O-rings), and uoropolymer-based tape within internal components of existing instrumentation. As a result of advances in analytical instrumentation, in particular ultra highperformance liquid chromatography (UHPLC), the use of uoroelastomers is widespread as seals and membranes and PTFE as inert surfaces inside analytical instruments and in some cases as tubings. The tubing can be replaced by polyetheretherketone (PEEK) or stainless steel tubing without a loss of performance in most applications. Some applications rely on uorinated solvents (e.g., triuoroethanol) and acids (triuoroacetic acid, pentauorobutanoic acids etc.) added to reversed phase LC-MS solvents, and specialty LC-columns are based on uorinated materials. Non-uorinated alternatives exist for both these uses. Peruoropolyether-based lubricants are also used as oils and greases in pumps and equipment; this can cause laboratory background contamination. Oil-free pumps exist and are reducing the laboratory background contamination, which is benecial for both the analyses and workers' health. To address concerns related to instrument contamination by PFASs, manufacturers offer a delay column to keep the instrumentborne PFASs from eluting with target analytes during the same time window. For the vast majority of laboratory applications, PFAS alternatives have been used historically or have been newly developed. Therefore, most applications fall within categories 1-2 in Table 1 and i.e., they are non-essential and replaceable. A small number of current laboratory applications may fall within category 3 as being essential and without appropriate alternatives, and thus further innovation for effective substitution is required. Peruorosulfonic membranes. These are uoroelastomers that exist in many forms and are used in a wide range of chemical synthesis and separation operations and in analytical instrumentation. These membranes are oen used in processes that displace less efficient historical methods that use more energy and/or generate hazardous materials and byproducts.78,79 Naon (CAS Number 66796-30-3) is the brand name for a peruorosulfonic acid membrane from Chemours (formerly DuPont) that consists of a peruorosulfonic acid copolymer with pendant sulfonic acid groups. It is stable in strongly oxidizing conditions and high temperatures. The density of sulfonic acid groups can be controlled during synthesis to select for variable ion exchange capacity, electrical conductivity, and various mechanical properties. One of the earliest principal uses of Naon was as a membrane in the chlor-alkali process, which is the large-scale industrial process that uses brine and electricity to produce the common chemical feedstocks, chlorine gas and sodium hydroxide.80 Historically these high-volume chemical commodities were prepared with brine in either asbestos diaphragm cells or mercury electrode cells. Both methods generate substantial quantities of hazardous wastes through either the mining and the fabrication of suitable asbestos membranes or the release of aqueous and volatile mercury wastes. Use of Naon copolymer as a membrane in the electrochemical cell allows for excellent conductance of ions necessary for the process, while maintaining separation of the two parts of the cell under highly caustic conditions. Peruorosulfonic acid membranes are also used in highefficiency fuel cells where, in one example, hydrogen and oxygen are pumped into different chambers within a cell that are separated by the membrane, giving rise to a continuous supply of electricity for various specialty applications. Peruorosulfonic acid membranes are also used as an acid catalyst in a wide range of chemical conversions leading to decreased energy inputs and higher-purity products. While it can be argued that peruorosulfonic acid membranes have made many chemical preparation processes more efficient and cleaner, it is also important to acknowledge that the impacts from their production and use are still poorly understood. Research at one uorochemical production site in Bladen County, North Carolina has documented that Naonrelated wastes have been released into the nearby Cape Fear River since at least 2012.81 Moreover, the relatively advanced drinking water treatment plant in the city of Wilmington, North Carolina, has been unable to remove these Naon-related wastes82,83 giving rise to a situation where approximately 99% of the residents of Wilmington now have measurable concentrations of Naon Byproduct 2 in their blood.84 No human health data are currently available for Naon Byproduct 2, and the human half-life of this material is likely to be on the order of months to years.83 The production of peruorosulfonic acid membranes has provided great utility by improving the efficiency of large-scale chemical syntheses while also reducing the emissions of other known hazardous byproducts (asbestos and mercury), but the current production process leads to the release of at least one persistent byproduct with near universal exposure in a downstream community. The use of peruorosulfonic acid membranes is currently judged to be category 3 (essential) in the chlor-alkali process. Before the use of Naon, there were concerns for worker safety and the environment associated with mercury and asbestos. The use of Naon as an alternative was the direct result of the chlor-alkali industry addressing these concerns. In the case of the use as a proton exchange membrane (PEM) in fuel cells, there are alternatives to peruorosulfonic acid membranes,85 but these are under development and not used as commonly as Naon (category 2). Although there is a lack of functional alternatives for certain applications, it is reasonable to insist that emissions of persistent and potentially toxic wastes from This journal is The Royal Society of Chemistry 2019 Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 | 1809 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Environmental Science: Processes & Impacts View Article Online Critical Review the production and use of peruorosulfonic acid membranes be quantitatively determined and minimized. Discussion The Montreal Protocol has provided a successful blueprint to assess the essentiality of a class of widely used persistent chemicals found to have signicant human and environmental health risks. Because of their extreme environmental persistence, and increasing data on their adverse effects including human healthrelated endpoints, PFASs are a prime opportunity for applying a similar approach to protect human health and the environment through the removal of these chemicals from non-essential uses. Our review of several key uses of PFASs demonstrates that currently a global phase-out of PFASs will be complicated, but it also indicates a number of starting points. In particular, different phase-out strategies will be required for each essentiality category. The essentiality of PFASs in the different use categories, based on our three categories in Table 1, is summarized in Table 2. Within a few of the larger use categories (e.g. textiles) certain uses of PFASs appear to be easier to phase out (e.g. leisure rain jackets) than others (occupational protective clothing) due to different technical performance requirements. Alternatives assessment Even if PFASs are assessed, according to the criteria in Table 1, to be non-essential in a particular use, and functional alternatives are available, this is only a rst step to phase out and responsibly substitute PFASs. It cannot be generally assumed that non-uorinated alternatives will be less harmful to human health and the environment than the PFASs they are replacing. The scientic discipline of alternatives assessment has Table 2 Essentiality of PFASs in selected use categories Table 1 Use Categorya Personal care products including cosmetics Ski waxes Fire-ghting foams (commercial airports) Fire-ghting foams (military) Apparel (medical: long operations) Apparel (protective clothing oil and gas industry) Apparel (medical: short operations, everyday) Apparel (military: occupational protection) Waterproof jacket (general use) Easy care clothing Food contact materials Non-stick kitchenware (uoropolymers) Medical devices (uoropolymers) Pharmaceuticals Laboratory supplies, equipment and instrumentation Peruorosulfonic membranes in fuel cells Peruorosulfonic membranes in chlor-alkali process 1 1 2 2 or 3 3 3 2 2 or 3 2 1 1, 2 or 3 1 or 2 1, 2 or 3 2 or 3 1, 2 or 3 2 3 a Note that the categories in the above table represent the current evaluation and may change in the future. established processes and best practices for identifying, evaluating, comparing, and selecting safer alternatives to chemicals of concern based on hazards, performance, and economic viability.86-88 This process can be applied to PFASs used in material components, nished goods, manufacturing processes, or technologies. Not all substitutions require direct replacements of a uorinated compound with a non-uorinated alternative (i.e. chemical alternative); a technological or engineering innovation (i.e. functional alternative) can be equally successful4 and should always be encouraged/prioritized over chemical alternatives. Multiple alternatives should be assessed for a given PFAS until an acceptable substitution is found. Oen, once an alternative is found for one use case, it may be easily adapted for other use cases of that chemical as well. In the assessment, once possible non-hazardous alternatives are identied, it is also important to consider multiple endpoints89 such as energy use, material use (incl. food waste, water use, packaging/machinery use and durability), and land-use (e.g. paper vs. plastic vs. glass), to avoid burden-shiing between different environmental and human impacts. When considering chemical alternatives for PFASs, the focus should be on the service the product should deliver. The compound should therefore be evaluated for performance using the specications required for the product, as opposed to comparing directly to the PFAS being replaced. Additionally, the potential for health hazard and potential for exposure - combined, these elements establish the health risks associated with the alternative - must be considered for the general public and vulnerable populations. Finally, additional considerations such as product longevity, persistence in the environment, and sustainability may be considered. Currently there are several established frameworks and evaluation metrics available for conducting alternative assessments.86,90 In the absence of a thorough evaluation, regrettable substitutions can occur. Challenges and opportunities in chemical regulation The Madrid Statement12 recommends limiting the use of PFASs in society. Although all PFASs are highly persistent (or lead to highly persistent transformation products), many of them do not comply with the usual concerns considered in international chemical regulation. It can be argued that their extremely high persistence alone should be cause for regulation and substitution,13,14 but the practical regulatory tools to implement this approach are currently lacking. Within the context of the EU REACH Regulation, it has been argued91 that the most effective way of regulating short-chain PFASs (as with the regulation of long-chain PFASs) is to identify them as Substances of Very High Concern under REACH Article 57, followed by a REACH Annex XVII restriction. Indeed, the EU has considered (e.g. in the case of the restriction of PFOA and its related chemicals), and is continuously considering ways to group PFASs in recognition of the impossibility of regulating more than 4700 PFASs individually. Another relevant regulatory framework is the UN Stockholm Convention on Persistent Organic Pollutants, which includes 1810 | Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 This journal is The Royal Society of Chemistry 2019 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Critical Review View Article Online Environmental Science: Processes & Impacts exempted uses similar to the essential-use exemptions under the Montreal Protocol. Under the Convention, the Conference of the Parties (COP) considers listing new persistent organic pollutants for elimination (Annex A), or restriction (Annex B), and/or involuntary production (Annex C) based on a recommendation from the Convention's Persistent Organic Pollutants Review Committee (POPRC). The Convention requires that the COP, "taking due account of the recommendations of the Committee, including any scientic uncertainty, shall decide, in a precautionary manner, whether to list the chemical, and specify its related control measures, in Annexes A, B and/or C" (Art. 8, Para. 9). As part of its deliberation of whether to list a chemical, the COP also considers whether to allow for any "specic exemptions" and/or "acceptable purposes". "Specic exemptions" is time-limited with one period of ve years with the possibility of one extension for another ve years, whereas the time period for the applicability of "acceptable purposes" is more open-ended. Currently, there is no clearly dened criteria for identifying "specic exemptions" and "acceptable purposes" set in the text of the Stockholm Convention. Such "essential uselike" exemptions are primarily identied through the work of the POPRC on a case-by-case basis. However, the COP has subsequently adopted detailed criteria for consideration of requests to extend specic exemptions. For production exemptions, the requesting party must have submitted a justication for the continuing need for the exemption that establishes that the extension is necessary for health or safety, or is critical for the functioning of society; included a strategy in its national implementation plan aimed at phasing out the production for which the extension is requested as soon as is feasible; taken all feasible measures to minimize the production of the chemical and to prevent illegal production, human exposure and release into the environment; and the chemical must be unavailable in sufficient quantity and quality from existing stockpiles. Finally, in the case of a party with an economy in transition, the party must have requested technical or nancial assistance pursuant to the Convention, in order to phase out as soon as feasible the production for which the extension is requested (see COP Decision SC-2/3, "Review process for entries in the Register of Specic Exemptions"92). We are convinced that having clear legal guidelines for what constitutes an essential use (a process started in this present work) will benet the Stockholm Convention and other regulatory frameworks by providing guidelines for determining how to apply the essential use-like exemptions, i.e., by balancing costs versus the societal benets of the use of a substance or product. A clear denition of essential use ensures that only those applications that are necessary for health or safety (or other purposes highly important to society as a whole) and for which non-uorinated alternatives are not yet available could receive exemptions when chemicals are listed under the Convention. Further, this approach would protect those uses that are legitimately deemed essential until appropriate substitutions can be identied. The way forward Innovation in the development of alternatives to PFASs is ongoing and many functional alternatives that provide adequate technical performance have been developed and put into practice for some use categories. However, in other use categories little innovation is under way, due to lack of nancial or regulatory drivers to change methods/production, signicant technical challenges, lack of awareness of the market opportunities, or the small size of the market. Innovation is being encouraged in countries like Denmark (e.g. substitution of PFASs in textiles) and in Sweden through the availability of government funding for industry-academic partnerships (e.g. the POPFREE project93 to encourage small companies to develop non-uorinated alternatives to PFASs). Furthermore, one of the four key areas in ECHA's 2018 strategy on substitution94 is to `Develop coordination and collaboration networks between all stakeholders, ranging from institutions, member states, industry, academia and civil society'. In some cases, the PFASs in a product or use will be determined as the only compound capable of delivering the required level of performance for that application. In these cases, it is recognized that immediate phase out will not be feasible. But this assessment is only based on current technologies. With clear legislative incentives, new technologies will typically be developed, and consequently PFAS uses in category 3 should continue to be reviewed for potential removal or replacement by new entrants to the market. In fact, use cases identied as category 3 should be the targets of industry and academic programs to develop innovations that may succeed in removing or replacing the PFAS with more sustainable functional alternatives. This system creates a market pressure to be the rst to develop new technologies. Chemical regulation on the other hand progresses slowly compared to product innovation, and assessment of individual PFASs is not feasible for protecting public health. It is simply unlikely that society and industry will spend the money and time to generate adequate data to risk assess >4700 PFASs. Therefore, we strongly recommend a grouping approach be employed, and for PFASs to be regulated as a group. Since regulation of the many thousands of PFASs by authorities is likely to be time consuming, it is important for industry (in particular product designers and manufacturers) to take voluntary measures that will contribute substantially in reducing the emissions of PFASs and their presence in products. There have already been several examples of retailers who through private procurement have phased out PFASs from their supply chains (e.g. IKEA, Lindex, and H&M in Sweden,15,17,95 COOP in Denmark,61 Vaude in Germany,96 L'Oreal in France97), which in turn puts pressure on chemical manufacturers to nd safer alternatives. We are convinced that our criteria on essential use can inform and encourage other retailers to consider phasing out and substituting PFASs in their products. These types of voluntary measures will in turn help regulators by demonstrating that functional alternatives exist. When policy makers face stakeholder groups from both sides, they can use data- This journal is The Royal Society of Chemistry 2019 Environ. Sci.: Processes Impacts, 2019, 21, 1803-1815 | 1811 Open Access Article. Published on 28 May 2019. Downloaded on 7/13/2023 10:06:56 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Environmental Science: Processes & Impacts View Article Online Critical Review driven essentiality assessments to support their decision making, e.g., to show why certain uses are not necessary and therefore can be restricted. This will speed up regulatory actions in support of phasing out non-essential uses of PFASs, without risk to health or safety applications. It is a formidable task to apply the essential use concept to all use cases of PFASs in detail. We have made a start here by illustrating how the concept can be applied to several use cases of PFASs, but to have a conclusive assessment for each use case described in this review, follow-up work may need to be covered in more detail (expanded, subdivided and rened) and engage relevant stakeholders with the necessary in-depth knowledge, where necessary. Although here we have focused on PFASs, the concept of essential use can also be applied in the management of other chemicals, or groups of chemicals, of concern. Conflicts of interest This paper does not necessarily reect the opinion or the policies of the German Environment Agency or the European Environment Agency. Acknowledgements This article has been prepared by the scientists collaborating as the Global PFAS Science Panel. We would like to thank the Tides Foundation for supporting our cooperation (grant 1806-52683). In addition, Stockholm University would like to thank the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) and Stockholm County Council for providing funding (SUPFES FORMAS project no. 2012-2148 and the SUPFES-Health project), and the University of Rhode Island would like to thank the US National Institute of Environmental Health Sciences (grant P42ES027706). The authors appreciate the contribution of Dr Andrew Lindstrom of the U.S. Environmental Protection Agency. References 1 OECD/UNEP, Toward a new comprehensive global database of per- and polyuoroalkyl substances (PFASs): Summary report on updating the OECD 2007 list of per- and polyuoroalkyl substances (PFASs), Organisation for Economic Co- operation and Development, 2018. 2 R. C. Buck, J. Franklin, U. Berger, J. M. Conder, I. T. Cousins, P. de Voogt, A. A. Jensen, K. Kannan, S. A. Mabury and S. 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