Document 02DqGgX6X2n3ROeL1rM5jqeb

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/356076561 A New OECD Definition for Per- and Polyfluoroalkyl Substances Article in Environmental Science and Technology November 2021 DOI: 10.1021/acs.est.1c06896 CITATIONS 72 12 authors, including: Zhanyun Wang ETH Zurich 86 PUBLICATIONS 5,511 CITATIONS SEE PROFILE Ian Cousins Stockholm University 366 PUBLICATIONS 19,191 CITATIONS SEE PROFILE READS 612 Andreas M Buser Federal Office for the Environment FOEN 34 PUBLICATIONS 849 CITATIONS SEE PROFILE Koichi Ohno National Institute for Environmental Studies 46 PUBLICATIONS 1,406 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Inorganic substances intake View project CERAPP: Collaborative Estrogen Receptor Activity Prediction Project. View project All content following this page was uploaded by Ian Cousins on 10 November 2021. The user has requested enhancement of the downloaded file. pubs.acs.org/est Viewpoint A New OECD Definition for Per- and Polyfluoroalkyl Substances Zhanyun Wang,* Andreas M. Buser, Ian T. Cousins, Silvia Demattio, Wiebke Drost, Olof Johansson, Koichi Ohno, Grace Patlewicz, Ann M. Richard, Glen W. Walker, Graham S. White, and Eeva Leinala Cite This: https://doi.org/10.1021/acs.est.1c06896 ACCESS Metrics & More Read Online Article Recommendations Downloaded via 79.136.43.8 on November 10, 2021 at 20:59:52 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. KEYWORDS: PFAS definition, cheminformatic tools, PFAS synthesis, PFAS universe, PFAS terminology P er- and polyfluoroalkyl substances (PFASs) comprise a class of chemicals that has attracted much attention since the early 2000s, when the hazards and ubiquitous occurrence of two PFASsperfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)were reported. Early communications used multiple terms such as "per- and polyfluorinated chemicals", "perfluorinated organics", "perfluorochemical surfactants", and "highly fluorinated compounds". In 2011, to harmonize communication, Buck et al.1 published a milestone paper, providing the first clear structural definition of PFASs and recommendations on the names and acronyms for over 200 individual PFASs. Since then, research and regulation has expanded from PFOA and PFOS to a much wider range of substances. In 2018, the so-called "Global PFC Group" led by the Organisation for Economic Co-operation and Development (OECD) and the United Nations Environment Programme (UNEP) published a list of over 4700 PFASs that contain a -CnF2n- (n 3) or -CnF2nOCmF2m- (n and m 1) moiety and that were known or likely to have been on the global market.2 The list included substances that contain fully fluorinated carbon moieties, but do not meet the PFAS definition in Buck et al. (2011) due to a lack of a -CF3 group in the molecule. Additionally, recent advancement of nontargeted analytical techniques enabled identification of many unknown PFASs in environmental and product samples. These developments provided motivation to reconcile the terminology of the PFAS universe, including a renewed look at the PFAS definition. Against this backdrop, a report on the terminology of PFASs was recently published under the framework of the Global PFC Group.3 This report reflects a three-year multistakeholder Received: October 12, 2021 XXXX American Chemical Society A https://doi.org/10.1021/acs.est.1c06896 Environ. Sci. Technol. XXXX, XXX, XXX-XXX Environmental Science & Technology pubs.acs.org/est Viewpoint Figure 1. Examples of substances that are, and are not, PFASs based on the new definition. international effort in reviewing the universe and terminology of PFASs to provide recommendations and practical guidance. We encourage stakeholders from academia, civil society, industry, and government to read the report and consider adopting its recommendations, wherever feasible, to help enable the coherent and consistent use of PFAS terminology across sectors and around the world. This Viewpoint provides an overview of the report. A REVISED PFAS DEFINITION The report details four major limitations with the previous definition in representing the PFAS universe: (1) omission of substances that have functional groups on both ends of the fully fluorinated carbon moiety (e.g., perfluoroalkyldicarboxylic acids); (2) inconsistencies in dealing with homologues that are fully fluorinated aliphatic cyclic compounds with or without a fully fluorinated alkyl side chain; (3) omission of substances with aromatic ring(s) in the nonfluorinated functional group(s) that can be cleaved in the environment and biota; and (4) use of the ambiguous term "highly fluorinated". To address these concerns, the report presents a revised, broadly inclusive PFAS definition: "PFASs are defined as f luorinated substances that contain at least onefully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e., with a few noted exceptions, any chemical with at least a perfluorinated methyl group (-CF3) or a perf luorinated methylene group (-CF2-) is a PFAS". The "noted exceptions" refer to a carbon atom with a H/Cl/Br/I atom attached to it. The rationale behind the revision is to have a coherent and consistent definition across compounds from the view of the chemical structure. The new definition was required to be easily implementable for distinguishing between PFASs and non-PFASs, and easily understood by experts and nonexperts alike. Figure 1 illustrates examples that are, and are not, PFASs. This revised definition captures the broadness of the PFAS universe, ranging from small molecules, to more complex aromatics with a perfluorinated methyl/methylene group on the side chain(s), to diverse polymers. Building on the revised definition, the report further provides (1) an explanation of how PFASs relate to other organofluorine compounds, (2) a comprehensive overview of known PFAS groups and their structural traits, including examples and notes on whether common names and acronyms B https://doi.org/10.1021/acs.est.1c06896 Environ. Sci. Technol. XXXX, XXX, XXX-XXX Environmental Science & Technology exist, and (3) some common synthesis routes of individual or groups of PFASs. PRACTICAL GUIDANCE ON HOW TO USE THE PFAS TERMINOLOGY The report highlights the need to distinguish between the general definition and user-specific working scopes of PFASs. The general definition is based on molecular structure alone and serves as a starting and reference point to guide individual users to have a comprehensive understanding of the scale and diversity of chemicals in the PFAS universe. Meanwhile, users may define their own working scope of PFASs for specific activities according to their specific needs by combining the general definition with additional considerations (e.g., specific properties, use areas). When such a working scope of PFASs is used, the report recommends that respective users clearly provide the context and rationale for selecting their working scope to ensure transparency and avoid confusion by others. The report further recommends using and building upon existing common terminologies such as in Buck et al. (2011) and well-defined common practices in organic chemistry, unless it is essential to deviate from them, to keep the consistent and coherent use of the PFAS terminology. As PFASs are a chemical class with diverse molecular structures and thus properties, it is recommended to properly recognize and communicate such diversity in a clear, specific and descriptive manner. A SYSTEMATIC MOLECULAR STRUCTURE-BASED APPROACH TO CHARACTERIZING PFASS When users define their own working scope of PFASs, they need to determine whether a compound falls or does not fall into their working scope. However, given the complexity and diversity of PFASs, it can be a challenging task to characterize and categorize PFASs based on chemical structures in a coherent and consistent manner, particularly for nonexperts. Different users may have different construction of working scopes, and there is no single categorization/grouping system that suits all. Therefore, the report provides a standardized approach for systematically characterizing PFASs based on molecular structural traits that will allow stakeholders to make their own categorization in a coherent and consistent manner. This system can be used to manually characterize and categorize PFASs, but the approach could also be used as inputs for developing automated cheminformatic tools.4 pubs.acs.org/est Viewpoint Authors Andreas M. Buser -- Swiss Federal Office for the Environment (FOEN), 3063 Ittigen, Switzerland Ian T. Cousins -- Department of Environmental Science and Analytical Chemistry (ACES), Stockholm University, SE10691 Stockholm, Sweden; 49 orcid.org/0000-0002-70358660 Silvia Demattio -- European Chemicals Agency, 00150 Helsinki, Finland Wiebke Drost -- German Environment Agency, 06844 DessauRofilau, Germany Olof Johansson -- Swedish Chemicals Agency, 172 67 Sundbyberg, Sweden Koichi Ohno -- Health and Environmental Risk Division, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan Grace Patlewicz -- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27711, United States Ann M. Richard -- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27711, United States; 0 orcid.org/0000-0003-2116-2300 Glen W. Walker -- Department of Agriculture, Water and the Environment, Australian Government, Canberra, Australian Capital Territory 2601, Australia Graham S. White -- New Substances Assessment and Control Bureau, Safe Environments Directorate, Health Canada, Ottawa K1A 0K9, Canada Eeva Leinala -- Environment, Health and Safety Division, Environment Directorate, Organisation for Economic Cooperation and Development, 75016 Paris, France Complete contact information is available at: https://pubs.acs.org/10.1021/acs.est.1c06896 Notes The authors declare no competing financial interest. Biography FUTURE WORK ON PFAS TERMINOLOGY Four areas are recognized for further work to facilitate clear and unambiguous communication: (1) a centralized PFAS nomenclature database/platform; (2) development of cheminformatic tools for automated, structure-based systematic characterizaing and categorizing of PFASs; (3) work on the characterization and reporting of polymers; and (4) work on organofluorine compounds not currently defined as PFASs, including many fluorinated aromatics. AUTHOR INFORMATION Corresponding Author Zhanyun Wang -- Chair of Ecological Systems Design, Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland; 49 orcid.org/0000-0001-9914-7659; Email: @ifu.baug.ethz.ch Dr. Zhanyun Wang is a senior researcher in the Ecological Systems Design Group at ETH Zurich, Switzerland. As an environmental chemist by training, his research interests focus primarily on understanding the life cycles and risks of various anthropogenic chemicals in the technosphere and natural environment. He is also very interested in exploring novel and pragmatic approaches to advancing sound chemicals management, enabling a sustainable C https://doi.org/10.1021/acs.est.1c06896 Environ. Sci. Technol. XXXX, XXX, XXX--XXX Environmental Science & Technology circular economy, and strengthening science-policy interface on chemicals and waste. ACKNOWLEDGMENTS Z.W. gratefully acknowledges financial support for his work from the Swiss Federal Office for the Environment (FOEN). We gratefully acknowledge Robert C. Buck (Chemours), Audun Heggelund (Norwegian Environment Agency), and Simone Schalles (German Environment Agency) for their contribution in drafting and finalizing the report, Urs Berger (UFZ, Germany), Stellan Fischer (Swedish Chemicals Agency), Linda Gaines and Laurence Libelo (USEPA) for their contribution to the early development of the project, and members of the OECD/UNEP Global PFC Group for their review and contributions to the report. The views expressed are those of the authors and do not necessarily reflect the views or official policies of their organizations and/or governments. REFERENCES (1) Buck, R. C.; Franklin, J.; Berger, U.; Conder, J. M.; Cousins, I. T.; de Voogt, P.; Jensen, A. A.; Kannan, K.; Mabury, S. A.; van Leeuwen, S. P. J. Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification and origins. Integr. Environ. Assess. Manage. 2011, 7 (4), 513-541. (2) Organisation for Economic Co-operation and Development (OECD). 2018. Toward a new comprehensive global database of perand polyfluoroalkyl substances (PFASs). http://www.oecd.org/ chemicalsafety/risk-management/global-database-of-per-andpolyfluoroalkyl-substances.xlsx; http://www.oecd.org/ officialdocuments/publicdisplaydocumentpdf/?cote=ENV-JMMONO(2018)7&doclanguage=en (methodology report) (021/9/1). (3) Organisation for Economic Co-operation and Development (OECD). 2021. Reconciling Terminology of the Universe of Per- and Polyfluoroalkyl Substances: Recommendations and Practical Guidance. Series on Risk Management No. 61. https://www.oecd.org/ chemicalsafety/portal-perfluorinated-chemicals/terminology-per-andpolyfluoroalkyl-substances.pdf (accessed 2021/9/1) (4) Sha, B.; Schymanski, E. L.; Ruttkies, C.; Cousins, I. T.; Wang, Z. Exploring open cheminformatics approaches for categorizing per- and polyfluoroalkyl substances (PFASs). Environmental Science: Processes & Impacts 2019, 21 (11), 1835-1851. pubs.acs.org/est Viewpoint View publication stats D https://doi.org/10.1021/acs.est.1c06896 Environ. Sci. Technol. XXXX, XXX, XXX-XXX