Per- and polyfluoroalkyl substances (PFAS) are a class of more than 6,000 contaminants of emerging concern that can harm both ecosystems and human health. These anthropogenic compounds contain carbon–fluorine bonds that make them stable and persistent in the environment, earning them the nickname “forever chemicals.” NCHRP Synthesis 630: Practices to Identify and Mitigate PFAS Impacts on Highway Construction Projects and Maintenance Operations , from TRB’s National Cooperative Highway Research Program, d…