A package of corn tortillas listing propylparaben as an ingredient. Meredith Rizzo/NPR hide caption itoggle caption Meredith Rizzo/NPR The Salt What Are Those Parabens Doing In My Tortilla? August 8, 2014 Parabens are chemical preservatives. I've spent years trying to avoid them in beauty products, but I'm not sure why. When I saw them on a nutrition label recently, I decided to investigate.