Anything plastic leaches when heated. This can be seen when plastic is melted, thus the smell and reason it turns to goop. When they are cooking with this the chemicals leak into the food. This same phenomenon happens when people microwave in plastic dishes. You may be able to find some research related to that. Try Dr. Mercola's website. He is usually up on the newest and baddest of products.
IN the meantime, I would refuse to eat anything cooked in those things and bring something else for your kids. It never amazes me how lazy American's get. WE can't even wash our the crock pot anymore.