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September 2006
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Are microwaves dangerous?
We uncover the truth about the alleged impacts on health

Mug inside a microwave.
COOKING UP MYTHS   Safety is essential when you use a microwave, but some concerns about these appliances are nothing more than urban legends.
A Web search of urban-legend purveyors reveals a treasure trove of rumors and myths related to microwave ovens. Have you heard the one about the elderly woman nuking her just-bathed pet in order to dry it? But other stories go beyond the bizarre and probably have you questioning how healthy it is to cook with one of these omnipresent appliances. One oft-told tale, for instance, details the perils of microwaving food in plastic containers.

Given the likelihood that you have a microwave in your home—nearly 44 million microwaves were sold from 2004 to 2006 alone—and with the freak-out potential of all this Internet innuendo, it's understandable that you might have questions about the alleged impact that microwaves have on your health. We've cut through the clutter for you below. After you get the lowdown, be sure to read our microwaves report. You'll get expert buying advice as well as Ratings (available to subscribers) of the latest models. And look for our upcoming report on microwaves in the February 2007 issue of Consumer Reports.

Click for answers:


True or False
  Microwaving with plastic releases cancer-causing
dioxins into food.

False. A popular Web rumor wrongly contends that plastics contain dioxins, which are a likely carcinogen. Some plastic wraps may, however, contain chemical plasticizers that add flexibility, and those can migrate into food when heated. The risks associated with consuming trace amounts of plasticizers are small. But more research is needed, so leave space between plastic wrap and food, or use a paper towel to cover your food instead. (Note that plastic containers not approved for microwave use could warp and leak hot food.)
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True or False
  Microwaves can leak radiation.


True, though it's unlikely. While the Food and Drug Administration does allow for some leakage (at levels far below any known to cause harm), it also requires that microwaves stop producing radiation once the door is opened. Bottom line: Don't operate a microwave if the door is broken.
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True or False
   Microwave radiation can cause cancer.


False. Intense microwave radiation can cause burns, temporary sterility, and cataracts, since it can heat body tissue just as it heats food. But you would have to be exposed to levels that are much higher than the allowable limits for leakage on newer ovens.
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True or False
  Microwaves can affect pacemakers.


Probably false. Since 1980 pacemakers have been manufactured with shielding, which should prevent electronic interference.
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True or False
  Microwave cooking sucks the nutrients out of food.


False. Microwave-cooked food may retain vitamins and minerals better than stove-top-cooked food because the microwave zaps food quickly and without much water. The longer you cook food in liquid, the more nutrients may seep out, which is fine for soups and stews, but it's a problem if you discard the liquid before eating. One study found that spinach retained all of its folate when cooked in a microwave, compared with 77 percent when cooked on a stove.
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True or False
  Heating water in a microwave could cause the liquid
to violently erupt.

True. Although burns and other injuries are rare, there have been reports of those injuries after plain water was heated past the boiling point and erupted out of its cup. When making hot drinks in a microwave, add sugar, tea, or coffee to the water before heating it and wait a minute before you remove the cup from the oven.
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The quiz first appeared in the October 2006 issue of Consumer Reports on Health.