©2014 Association of Schools and Programs of Public Health Perfluorinated compounds (PFCs) have been in use for more than 60 years.1 Perfluorooctanoic acid (PFOA) was a primary PFC product at the 3M facility in Cottage Grove, Minnesota, but perfluorooctane sulfonate (PFOS) and other PFCs were also produced. The PFCs show high thermal, chemical, and biological inertness—properties that make them useful for certain industrial purposes, but at the same time also resulted in environmental persistence and potential human health risk.2 Little was published in scientific journals on PFC toxicology until the 1980s, perhaps because compounds resistant to breakdown were erroneously considered inert.3 Gradually, evidence for persistent, bioaccumulative effects has emerged, raising warning signs. A chronology of important events in understanding PFC health risks is provided in the Figure.