Communities in Pennsylvania and New Jersey have grown increasingly worried about a class of toxic chemicals known as PFAS. These “forever chemicals” are in lots of consumer products from pizza boxes to dental floss. And they’ve been found to have contaminated soil and drinking water. But as fears about the potential health effects grow, researchers and regulators say they still have more questions than answers. Why don’t we know more about PFAS? WHYY health and science reporter Dana Bate explains on this episode of The Why.