A two-page summary of the information on per- and polyfluoroalkyl substances (PFASs) contained in the 2020 UNEP Assessment Report on Issues of Concern: Chemicals and Waste Issues Posing Risks to Human Health and the Environment and the 2019 Global Chemicals Outlook II. The PFAS family is composed of thousands of synthetic organic chemicals that contain at least one perfluorocarbon moiety (e.g. –CF₂–) in their molecular structures. They are used or applied most often where extremely low surface tension and/or durable water and oil repellence is needed (e.g., in various firefighting foams and for surface treatment of textiles).