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
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. 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 water...is 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
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
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
In addition, operate and maintain the oven in ways that minimize
* 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
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."
Read more about microwave ovens, the healthfulness of microwaved
food, and where to purchase microwave oven testers at
Hailed as "The Queen of Green" by the New York Times,
Debra Lynn Dadd has been a leading consumer advocate for products
and lifestyle choices that are better for health and the
environment since 1982. Visit her website -
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