Is plastic really dishwasher- and microwave-safe?
Reusing plastic containers again and again may seem like a wise environmental choice, but do some research before you put food containers in the dishwasher and microwave.
Manufacturers make food storage containers out of plastics that are lightweight and disposable. Sometimes they are made from bisphenol-A (BPA), a chemical widely regarded as a potential carcinogen when heated. Dishwashers heat up to between 130 and 170 °F (55 and 75 °C), depending on which wash cycle you choose. Detergents also contain harsh cleaning agents which can contribute to the deterioration of the plastic’s integrity, even if you can’t see them with your naked eye, and can cause leaching of chemicals into the foods you store in them and also onto the other items in the dishwasher. The National Toxicology Program, an interagency program within the U.S. Department of Health and Human Services, advises against washing plastic items in the dishwasher—even in the upper rack which maintains cooler temperatures than the lower rack.
And that’s not the only danger to avoid. Did you know that microwave ovens heat the water in food to 212º F (100º C)? Alex Formuzis of the Environmental Working Group (EWG), a national consumer safety and research organization, says you should not microwave food or drinks in plastic containers—even those that claim to be "microwave safe." Microwaves heat unevenly, creating hot spots where the plastic is more likely to break down. And don’t forget that putting hot food into a plastic container can have the same effect. Fatty foods or highly acidic (spicy) ones placed in plastic containers can also cause similar results!
To wash your plastic containers safely, do so by hand with soap and old-fashioned elbow grease.