Well, I try to avoid eating my styrene plates and cups, and ingest "pickling" agents other than formaldehyde, so I'd say I'm purty safe. Pretty much everything, they're going to find out, will cause cancer. Still, every time I see a commercial where someone says "caused cancer in lab rats", I feel like writing them and telling them to stop giving the stuff to the dam rats!
Since you're a modeler Tim, and I assume that's your main concern with this, I would imagine it's along the same lines as plastic forks etc, that it's very slight and not really worth worrying about.
It might make you larger, but lighter. They use it in boats and life jackets, so you'll get real big, but when you get in the water, you'll float like a cork.
Seriously though, I remember many years ago when they suggested burning styrofoam cups could release carcinogens. I rarely use them anyway, and usually for drinking out of, not burning.