Microwave safe plastic is plastic that has been designed for use in microwaves. All of these plastics undergo testing by the Food and Drug Administration (FDA) to ensure that the plastic will retain its shape under high temperatures and have the least amount of leaching possible. Leaching is considered to be safe provided that the amount of leaching is within certain parameters for the type of plastic used.
There are many different types of microwave safe plastic. Single use containers should be thrown away after they’ve been heated up once. They are designed and approved for one use only and further usage may cause unsafe leaching into food. Single use containers are generally thought of as safe if you follow the heating instructions found on the package.
Plastic wrap that's designed for microwaving should be loosely placed over food. Be sure to follow manufacturer’s instructions as some manufacturers recommend at least an inch between the food and the plastic wrap. There is some controversy about the safety of this type of plastic wrap. The FDA indicates that as long as you follow manufacturer’s instructions you will be safe. The FDA also acknowledges that you should not use plastic wrap to heat high fat foods as this will cause a greater amount of di(ethyhexyl)adepate (DEHA) to leach into food.
DEHA is a known cancer causing chemical and is used in microwave safe plastic wrap. DEHA has also been linked to breast cancer in women and low sperm counts in men. The FDA has not yet created regulations for this chemical; however they recommend no more than 0.05 parts per billion. When using plastic wrap to heat high fat foods, as much as 500 parts per billion of DEHA can migrate into foods, according to private testing.
Never use plastic containers that do not indicate they are safe for the microwave. There is an international seal for microwave safe plastics. It is square with a small dish at the bottom and 5 rows of waves, above the dish, stretching across the square. If your plastic container doesn’t have this seal or have instructions for microwave use you should consider the plastic unsafe for the microwave. Not only are these containers not microwave safe and have the potential to leach plastics into your food, they may melt or warp causing spills or burns.
To ensure your plastics are safe in the microwave consider these tips. When choosing a plastic, to use in the microwave, be sure to read any manufacturer’s instructions carefully. If your microwave safe plastic is showing wear, consider replacing it. Toss out any single use containers once they have been used.