LIFESTYLE

98 november 2010

Microwave ovens have been around for decades. Terminology such as"radiation" and slang expressions such as "nuking" have helped to shroudthese ovens in an ongoing controversy.

In Canada 90 percent of households areestimated to own these appliances, yetconsumers may still wonder whethermicrowave ovens pose a danger to theirhealth. What's the truth behind the safetyof microwave cooking.'

WHAT ARE MICROWAVES?Microwaves are a form of electromagneticradiation. They are part of theelectromagnetic spectrum that includesradio waves, infrared (we know it as heatfrom the sun), visible light, ultravioletlight. X-rays, and gamma rays.

This non-ionizing radiation has theenergy to cause atoms within moleculesto vibrate, but not enough energy toremove electrons from the atoms.

During the development of radar inWorld War II, an engineer accidentallydiscovered that the radar waves usedto detect planes could also heat food.The first microwave oven, called theRadarange, came out in 1947. The firstconsumer, countertop model came out20 years later. Microwave ovens soonbecame a popular household appliance.

HOW MICROWAVEOVENS WORKEvery microwave oven has a magnetronwhich produces the microwaves. Themicrowaves are reflected within themetal interior of the oven, pass throughcontainers such as glass and plastic,and are absorbed by the food. Themicrowaves cause the molecules in thefood to vibrate (especially those of water,fats, and sugars). The vibration results infriction which creates heat.

THE CONTROVERSYMany people believe that microwaveovens are unsafe. They contend that:

• microwaves alter food composition,producing toxins and carcinogens

• the nutritional content of foods are lostor altered so that there is very littlebenefit to the consumer

• microwaves produce electromagneticfields (EMF) that negativelyaffect people

Many who support these claims citea few studies and one seemingly relateddeath. Unfortunately, these studies areold, unreplicated, and have never beenpublished in peer-reviewed journals (anecessary litmus test for all health-relatedclaims in alive).

AN UNUSUAL LAWSUITNorma Levitt's death in 1991 resultedin a lawsuit against the Oklahomahospital and staff who operated onher. The lawsuit alleged that bloodwarmed in a microwave oven was usedin a transfusion following a routine hipreplacement on Levitt. The hospitalmaintained the cause of death was from ablood clot and not from the microwavedblood. The court found the hospital andstaff not guilty.

From a scientific point of view,there is no correlation betweenmicrowaved blood that is injectedinto the bloodstream and the idea thatmicrowaves must be altering foodwhich, if ingested, could be deadly. BobSchiffmann, a microwave consultantand process developer since 1961,believes that "the Web is filled withmisinformation that leads to concerns."

THE FACTSHigh levels of microwaves can causecataracts, burns, and temporary sterility,but the emissions from microwave ovens

Microwave ovens may have minimalradiation leakage. Health Canada hasstrict limits which are far below those

known to cause health concerns.

It is important to maintain yourmicrowave to reduce the risk of leakage.

The main source of potential leakageoccurs at the oven door, so ensurethe door is clear of debris and in

good working order.

are far below these levels and do not posea danger. Professor Tony Muc of theUniversity of Toronto states that, "the[Health Canada] guidelines incorporatesignificant safety factors which furtherreduce any possible risk [to consumers]."

Muc explains that microwaves heatfood by "heating the water moleculesthat form the bulk (much more thanhalf̂ of most foods. The other moleculesin the food are like peas in a pot ofboiling water. They get hot from contactwith the hot water but they are notdegenerated or altered."

There are no studies that concludethat consumption of microwave-heatedfoods will result in sickness or disease.In fact, Muc states that heating food ina microwave oven has "much the samesort of effect as that produced by infraredradiation [heat] under a broiler."

To dispel the nutritional degradationmyth, Schiffmann explains that allcooking affects the nutritional content offoods. This is because cooking involvesraising the temperature of foods, andcertain vitamins are sensitive to heatwhich can cause a reduction in nutritionalcontent. In general, microwavingvegetables retains more of the nutrientsthan boiling as water is the culprit formost reductions in nutrients. X>

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LIFESTYLE

WHICH CONTAINERSARE SAFE?

'^Plastic Containerssuch as margarine

and yogourt tubs areintended for one-timeuse and should not be

used to cook food."

GLASS AND CERAMIC

>> When cooking food in a microwaveoven be sure to use containersdesigned for such a purpose.

» Glassware is a good choice.

» For ceramic ware plates, reter to themanufacturer's directions to be sure.

S

PLASTIC

» Only use plastic containers labelledas microwave sate.

» It a container looks damaged ordiscoloured, do not use it.

» Plastic containers such as margarineand yogourt tubs are intended torone-time use and should not be usedto cook tood as they could melt andpotentially leak chemicals into the tood.

» Don't use a container if you have anydoubts about it being sate.

> Never use thin plastic storage bags,brown paper or plastic grocerybags, newspapers, or aluminum toilin the microwave.

> It using plastic wrap over yourcooking container, ensure it doesn'ttouch the tood as it may melt once thetood is heated.

• It you are going to store cooked tood inplastic, make sure the food has cooledtirst and then refrigerate immediately.

WHAT ARE THE DANGERS?No dangers have been linked to cookingfood using a microwave oven rather thanusing a conventional oven. The dangerswith microwave ovens are similar tothose of any other oven: over-cookingthe food can reduce the nutritionalcontent; and burns can result from skincontacting the hot food or container.

As Schiffmann puts it, "other thanoverheating foods, the only real danger of amicrowave oven is dropping it on your foot."

Dangerous micro-organismsMicrowave ovens can heat unevenly,particularly if the food is thick or dense.Manufacturers try to overcome thischallenge with the use of carousels and

fans. Care should be taken to stir thefood during the cooking process or allowstanding time (time taken for heat topass through all of the food) so that allpotentially dangerous micro-organismsare destroyed.

CURRENT RESEARCHMicrowave technology has come a longway from the early days of radar. Withmore and more consumer products on themarket that use radio and microwaves,electromagnetic radiation and associatedfields are being studied to determine if weare at risk from low-level exposures.

Current research and testingsupports microwave oven safety fordomestic use. When deciding whether

to use a microwave, be critical aboutthe information you find. If youuse a microwave, always follow themanufacturer's guidelines and routinelyclean and inspect your microwave oven.

Ultimately, using a microwave is apersonal choice. Despite current researchto the contrary, some people believefurther studies will reveal evidence ofmicrowaves' harm. But for those whoenjoy the time-saving convenience amicrowave oven offers, research seemsto confirm that the controversy is morehype than fact. 3

Jason Bosher is a writer with a sciencebackground who uses his microwaveoven regularly.

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