Debra Lynn Dadd


Safety of Microwave Ovens & Healthfulness of Microwaved Food

Microwave ovens do have benefits. They are certainly convenient. They are more energy-efficient than other cooking methods. But are they safe? And do they produce food that contributes to the health of our bodies?

While there is not enough evidence to require warning labels on microwave ovens, or to remove them from the market, there is concern both about the safety of our exposure to microwaves and the healthfulness of microwaved food.

The dangers of microwaves

Even microwave ovens that are functioning perfectly emit microwaves. Safety standards set by the US Food and Drug Administration (FDA) allow microwave emissions of up to one milliwatt per square centimeter (1mW/cm2) when the oven is purchased, and up to 5mW/cm2 after the oven has been in use. Studies on industrial exposure recommend that daily exposure should not exceed one milliwatt for more than one minute. Average home use of microwave ovens far exceed this.

Workers who are exposed to microwaves on the job experience headaches, fatigue, irritability, sleep disturbances and other symptoms.

How microwaves affect food

Advocates of microwaved food claim that it is healthier because it retains vitamins, but the University of Minnesota disagrees:

"Microwaves ... are not recommended for heating a baby's bottle... Heating the bottle in a microwave can cause slight changes in the milk. In infant formulas, there may be a loss of some vitamins [italics mine]. In expressed breast milk, some protective properties may be destroyed.... Warming a bottle by holding it under tap water or by setting it in a bowl of warm much safer".

If heating formula in a microwave can cause it to lose vitamins and protective properties in breast milk to be destroyed, then it can do the same to the foods we eat. While the effects may not be immediately observable, a regular diet of microwaved food may have long-term health consequences.

Two Swiss researchers found that microwave cooking changes food nutrients significantly. Blood samples taken from eight individuals immediately after eating microwaved food revealed, among other things, an increase in the number of white blood cells--often a sign of poisoning.

> article with many documented references on how microwaves affect the healthfulness of food (including warnings from the FDA, Consumer Reports magazine...and even Ann Landers!)
> results of my experiment attempting to sprout seeds in water heated in a microwave oven

CAUTION...Microwave ovens are now used in many restaurants in addition to convenience stores. They may be behind the scenes where you can't see them. Many chain restaurants prepare food off-site and then simply heat up the food in a microwave at the restaurant. Airplane food is microwaved. So if you want to eat food that has not been microwaved, you'll need to watch for microwave oven use and ask questions.

Safety tips for using microwave ovens

I personally have never had a microwave oven in my own kitchen and am finding that it had been difficult to get people to give up their microwave ovens. Some of the generation who grew up with microwave ovens apparently don't know any other way to heat food (really!).

If you choose to use a microwave oven, Consumer Reports magazine suggests you stay as far as possible from the oven while it is in operation.

In addition, operate and maintain the oven in ways that minimize leakage:

  • make sure the oven door closes properly
  • prevent damage to hinges, latches, sealing surfaces and the door itself, and make sure these are in good working order
  • make sure no soil or food residues accumulate around the door seal
  • avoid placing objects between the sealing surfaces.

For peace of mind, test your oven for leakage. Testers can be purchased online at Mr. Microwave and InspectorTools.

When cooking in a microwave, use heat-resistant glass, not plastic. The Food Safety Inspection Service (FSIS) of the USDA warns against using foam trays, plastic wraps, and cold-storage containers such as margarine tubs, whipped-topping bowls and cottage cheese cartons. According to the FSIS flyer "A Microwave Handbook," these containers "are not heat stable at high temperatures. They can melt or warp from the food's heat, possible causing chemicals to migrate into the food."


Copyright ©2005 Debra Lynn Dadd - all rights reserved.