"I've heard using plastic food containers is dangerous." Some plastics are not safe when heated. 20-7.png Bisphenol A (BPA) is a chemical found in products made with plastic including cups, the inner lining of aluminum cans, and some water bottles. These plastics are labeled with the number 7 in a triangle.Tests have shown that BPA is linked with various health problems such as cancer, thyroid disease, early puberty in girls and hyperactivity.Because BPA leaches out into food at a faster rate when heated, avoid putting #7 plastics in the microwave or dishwasher.Try This The next time you use your microwave, use glass instead of plastic to heat foods. Filed under: General Nutrition Is it okay to microwave food in plastic? Safety when using the microwave and risks of using plastic containers containing BPA. Is It Ok to Microwave Food in Plastic? Video of Is It Ok to Microwave Food in Plastic?