styrofoam and cats

Is styrofoam hazardous to cats/kittens? I caught Gizmo and Scooter going thru a bag of those peanut styrofoam pieces tonight. They didn't eat them, but they were chewing on it.

The old kind or the new kind that dissolves in water? Not that I know if it makes a difference . . .

Let me just ask.....Would you eat or chew on styrofoam? I certainly wouldn't. They do not list the ingredients used to make it. I would assume that they use some pretty harsh chemicals in the making. I would make an effort to keep such things out of the cats reach.