You have to realize even if your "natural" food is free of toxins, the traditional cooking methods are likely to produce them, especially in grilling, frying and baking. And the worse part is the chemistry there is complex and may differ depend on source material and actual cooking method. On the other hand, the plastics are simpler and easier to analysis of possible transfers(or changes) in given temperatures. For the types approved for microwave uses there are more research done than say the interaction between beef and your pan. So I wouldn't worry too much about it.