This study represents efforts in 2017-108 to update the OECD “Lists of PFOS, PFAS, PFOA, PFCA, Related Compounds and Chemicals That May Degrade to PFCA”, which was last updated in 2007, to provide a comprehensive list of per- and polyfluoroalkyl substances (PFASs) that may have been on the global market. The study utilises publicly accessible information sources and resulted in identification and manual categorisation of 4730 PFAS-related CAS numbers. Based on lessons learned from identified limitations, gaps and challenges, opportunities for future improvement have also been identified. In particular, there is a need for an intensified dialogue and cooperative actions across regions and sectors, designing and fostering new types of public-private partnerships to facilitate effective and efficient information exchange between public and private sectors within the field of PFASs. Additional recommendations include (1) expansion of the current terminology of PFASs to reflect all substances and resolve issues identified (e.g., no clear cut-off values between some substance groups), (2) development of a web-based knowledge base to share up-todate information on PFASs across sectors and regions, and (3) continuous support to address critical knowledge gaps including the degradability of many non-studied PFASs.