A lot of times animal byproducts go into making plastics, thus the attraction that cats have for them. The plastic bags the grocers use, most times, the manufacturer uses fish oils to process the plastic and make them so shiny. I have to hide all our plastic shopping bags from one kitty because she just goes for them. It is really dangerous and you need to try and keep plastics away from your cat. Good luck at that, plastic is everywhere anymore.