867. Can one's health be adversely affected by the use of certain wraps, films, or containers, when heating food in the microwave?
When various plastics become hot, their molecules become more mobile. The most obvious such case is when a plastic actually melts. But even before it melts, a plastic can begin to lose molecules to objects that are touching it. However, the plastics used in cooking are pretty non-toxic, so that even eating pieces of those plastic won't cause you any significant trouble. On the other hand, I would be careful with plastics that weren't intended for cooking. Some non-food related plastics are mixed with additives called "plasticizers" that keep them softer than they would be if they were pure. These plasticizers have a tendency to migrate out of the plastics, giving such things as "vinyl" their characteristic odors. Heating a plastic containing a plasticizer can drive this plasticizer out of the plastic and into something else. I don't think that it's a good idea to eat plasticizers so I would suggest not cooking with plastics that weren't intended for use with food. Still, not all plasticizers are bad—water is an excellent plasticizer for such common plastics as hair and cotton.