How Safe Are Microwave-Safe Plastics?

Plastic containers labeled “microwave-safe” won’t melt or crack, and they have been tested under typical conditions of use to see if chemicals from the plastic wind up in food. What the term "microwave-safe" basically means is that any chemicals that leach from the container into food appear at levels far below those shown to have any health effects.

There is cause to be wary of this claim however, and whether it says “microwave-safe” or not, #7 polycarbonate plastic should not be used in a microwave, since it leaches hormone-disrupting bisphenol A (BPA), especially when heated. BPA has been associated with reproductive abnormalities, obesity and insulin resistance in animal studies and a number of animal studies have found abnormalities at levels of exposure similar to what people have in their bodies today. Over 90% of the general population carries residues of BPA in their bodies.

What you can do

• Don't store or microwave food in polycarbonate #7 plastic containers. 
• Microwave foods in glass or ceramic containers or on undyed paper towels. If you cover a food dish with plastic wrap, be sure it does not touch the food and leave vents for steam to escape.