ITRC’s Per- and Polyfluoroalkyl Substances (PFAS) Team is pleased to announce the release of the updated PFAS-1 Technical and Regulatory Guidance Document! This update includes a broad expansion in the discussion of PFAS in several contexts, including naming conventions, bioaccumulation, treatment technologies and sampling and analytical methods. Other sections of the document have also been selected for additional content, including information in regarding the health effects of PFAS, the mechanisms of fate and transport of PFAS, and the change to fluorine free firefighting foams. The 500+ page document also includes case studies and stakeholder perspectives, discusses technical challenges in addressing PFAS, and provides additional references to relevant scientific literature. The ITRC PFAS team continues to review new research to develop new content for future updates.