I never want a Styrofoam as a food container, but avoiding it is hard. Seminar managements usually serve coffee in Styrofoam cups. Packed meals in canteens, karenderya, fast foods and workshops usually come in Styrofoam packaging. As of date Styrofoam is the most affordable and convenient way to pack ready to eat meals.
I had a bad experience with this Styrofoam thing. A friend of mine bought two pack lunches, one for her and one for me. She reheated the food in microwave oven before serving. To my surprised, the food tasted so bad. I did not tell her and munched all the bad tasting food. She will surely get embarrassed.
I lifted the fried chicken and noticed the curved underneath. The heat produced by the microwave melted it. Some melted substances migrated to food. Some Styrofoam products are safe for microwave heating at certain limits, some are not. They release plasticizers that could cause body harm.
Update as of May 22, 2012, The oil in fried chicken also played a significant role in melting lunchbox. See more explanations on, “Bad Encounters With Oil Plus Polystyrene / Styrofoam”
Microwaves act by exciting water molecules thus producing heat. A piece of microwavable polymer will not produce heat inside microwave oven. However, a plastic or a Styrofoam will still produce heat and melt if filled with moisture rich food before the microwave operation. So a microwave safe Styrofoam might not do the trick.
Packed meals in 7-Eleven 24 Hour Convenient Stores are wrapped with paper cartons. Customers may get them from cold storage and reheat in microwave oven. I guessed the store management is well aware about the bad effects of Styrofoam on human health and environment.