Perfluorinated and polyfluorinated alkyl substances, or PFAS chemicals, are fully synthetic – meaning they’re not found in the natural world. They’re called “forever chemicals” because they are extremely resistant to either chemical and biological degradation. Experts, including Fulton Schools Professor Rolf Halden, an environmental engineer who directs ASU Biodesign Center for Environmental Health Engineering, explain that while PFAS substances work well in many consumer products they can also be a threat to human and environmental health. Engineers and scientists are working on ways to remove PFAS chemicals from environments where they present serious threats.  They want to see use of more “green chemistry” — which has useful properties, but will become benign in the environment or quickly break down.