The Marvelous Microwave Mishaps

Back during freshman year, I used to have a wall of shame list for my roommate. She managed to set multiple items on fire, and the list included the following.

Top 3:

  1. Burning a hole through the center of a cookie. She had nuked the already-cooked item for about 2 minutes just to “get it warm.”
  2. Placing a soup container (the milk carton kind) in the microwave. It had metal on the bottom. (In her defense, she didn’t notice).
  3. Burning popcorn. It appears to be a pastime in college dorms these days.

Many of these incidents resulted in me turning on a bajillion fans, opening the window, and praying that the fire alarm on our 10-story building would not go off. It’s hard enough being accepted as a freshman as it is. Lately I’ve been contemplating what exactly IS safe for the microwave, as I’ve been told that Styrofoam (such as the ever-popular to go containers) is not safe. Others disagree. So I did some research to get the low-down. Here’s the inside scoop:


  • Microwavable takeout dinner trays are formulated for one-time use only and will say so on the package.
  • Any utensil labeled for microwave use.
  • Heatproof glass (such as Pyrex, Anchor Hocking, etc.).
  • Glass-ceramic (such as Corning Ware).
  • Oven cooking bags.
  • Baskets (straw and wood) for quick warm-ups of rolls or bread. Line the basket with napkins to absorb moisture from food.
  • Most paper plates, towels, napkins and bags. For optimal safety use white, unprinted materials.
  • Wax paper, parchment paper, heavy plastic wrap. Do not allow plastic wrap to touch food; vent it to allow a steam escape.
  • Heat-susceptor packaging.


  • Most water bottles and plastic tubs or jars made to hold margarine, yogurt, whipped topping, and foods such as cream cheese, mayonnaise, and mustard are not microwave-safe. These materials are not approved for cooking and chemicals can migrate into food.
  • Don’t microwave plastic storage bags or plastic bags from the grocery store.
  • Don’t allow plastic wrap to touch food during microwaving because it may melt. Wax paper, kitchen parchment paper, or white paper towels are alternatives.
  • If you’re concerned about plastic wraps or containers in the microwave, transfer food to glass or ceramic containers labeled for microwave oven use.
  • Brown paper bags and newspapers.
  • Metal pans.
  • Foam-insulated cups, bowls, plates or trays.
  • China with metallic paint or trim.
  • Chinese “take-out” containers with metal handles.
  • Metal “twist ties” on package wrapping.
  • Food completely wrapped in aluminum foil.
  • Food cooked in any container or packaging that has warped or melted during heating (USDA, 2011)

Another Helpful Tip:

  • Before microwaving food, be sure to vent the container: Leave the lid ajar, or lift the edge of the cover. This will help you to avoid the volcano effect during heating.

Did you know? Styrofoam is actually a kind of plastic. It’s the brand name and it’s generic name is polystyrene. (Harvard Medical School, 2006)

I found this helpful chart you can use when reading labels:

Type 1 – polyethylene terephthalate (PET)

May be safe if marked “microwave safe”, although some recommend against food contact when microwaving.

Type 2 – high density polyethylene (HPDE)

May be safe, although some recommend against food contact when microwaving.

Type 3 – PVC, polyvinyl chloride, vinyl

Do not use in microwave. Also, PVC often contains bisphenol A (BPA)

Type 4 – low density polyethylene (LDPE)

(mixed commentary regarding microwave safety)

Type 5 – polypropylene

May be safe, although some recommend against food contact when microwaving. “Type 5” are the most commonly labeled “microwave safe”. Despite this, I have observed “Type 5” containers with partially dissolved surfaces, apparently from microwave use.

Type 6 – polystyrene, styrene, polystyrene foam

Not heat stable. Do not use in microwave.   Do not microwave food in a styrofoam container! In addition to not being heat stable, polystyrene is a potential human carcinogen and usually contains bisphenol A (BPA).

Type 7 – polycarbonate; “other” (can contain bisphenol A (BPA); most polycarbonate contains bisphenol A)

Do not use in microwave. (Note: Polycarbonate nursing bottles which have been boiled or washed more than 20 times or are badly scratched should be thrown out.)

(Protigal , 2010)

Feel free to check out the links below for more information.


Harvard Medical School. (2006, July). Microwaving food in plastic: dangerous or not? Retrieved from

Protigal , S. (2010, May 18). Which plastics are “microwave-safe”? Retrieved from

USDA. (2011, May 24). Microwave ovens and food safety. Retrieved from

*This is Bonnie’s first blog on RYH! You can check out her profile on the right-hand side to learn more about her.


  One thought on “The Marvelous Microwave Mishaps

  1. August 25, 2011 at 5:36 am

    I definitely learned the twist ties rule the hard way. Another great article, Bonnie! Always enjoy reading them!


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