Many household kitchens have a sizable collection of plastic containers and lids, some specifically made for microwaving, others recycled from empty margarine tubs and takeout food orders. Many of these plastic containers are used for reheating food in the microwave. However, controversy exists over the safety of using plastic in the microwave.
Chemicals in Plastics
Bisphenol A, also known as BPA, is a chemical component of polycarbonate plastics used for food and drink packaging. BPA and other plasticizers are used to give plastic flexibility. These chemicals are stable in unheated plastic and are present at levels far below human toxicity. However, heating plastic containers can cause chemicals to leach into the food.
Animal studies have linked BPA to increased estrogen levels and systemic toxicity. According to the U.S. Department of Health and Human Services, there is currently no evidence that BPA is harmful to human beings, but concern about regular exposure, particularly to children, has led to a call for further studies.
There is no official manufacturer's symbol that alerts consumers as to which plastic containers are microwave-safe and which are not. Some plastic containers have the label "NSF" on the bottom, which signifies that the National Safety Foundation, a non-governmental, non-profit company has verified that the product is in compliance with U.S. Food and Drug Administration's general safety standards for plasticware. This does not mean that plastic containers that do not carry that symbol are unsafe for use in microwave ovens. When buying plastic containers, read the outer packaging, which should clearly indicate whether the product is intended for use in the microwave.
The Bottom Line
Use cold storage tubs from foods such as margarine or cottage cheese and plastic containers from takeout food for saving leftovers in the refrigerator. Transfer the contents to a glass, ceramic or microwave-safe plastic container when reheating the food. If plastic containers melt or warp after microwave use, throw them away. Or use those takeout containers to hold non-food items only.
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