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Microwave Ovens - Safe?

By HHI Staff

As everyone knows, microwave ovens can dramatically shorten cooking times. So, it’s not surprising that, in the several decades since their introduction to consumers, their use has increased to the point that it’s a rare household without one. However, there are potential drawbacks and concerns associated with microwave ovens.

How Microwave Ovens Work

Many healthy persons cook with microwaves because they can heat up prepackaged microwave dinners, reheat leftovers, make hot water quickly for coffee, and pop popcorn without oil, but these people still use their electric or gas oven for other types of cooking. On the other hand, some sensitive persons who find that they simply can’t tolerate their regular stove turn to microwave ovens as their main (sometimes only) method of cooking. Interestingly, few people actually know how microwave ovens work.


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As it turns out, microwave ovens are equipped with a special electron tube known as a magnetron. This device emits a narrow stream of microwave radiation which is the same type of energy as radar. (Interestingly, "radar" stands for radio detecting and ranging.) 


How does microwave radiation (radar) actually cook? It seems that radar is powerful enough to pass through paper, glass, and china quite easily. However, it has more difficulty passing through liquids, including the microscopic liquid molecules present within most foods. In fact, the radar waves becomes trapped in the liquid, and this causes the liquid’s molecules to energize and vibrate rapidly. As vibrating liquid molecules collide with each other, they create friction. Interestingly, it’s the heat produced by this friction that actually cooks the food. Because microwave ovens create internal friction almost immediately, they don’t require preheating or lengthy cooking times. Conventional ovens, on the other hand, slowly heat foods from the outside surface inward.


Unfortunately, complex foods (which may have areas of high moisture content, as well as areas of lower moisture content) or fairly dry foods, don’t often cook particularly well in microwave ovens. In addition, browning is not possible unless special devices and/or sprinkled substances are used. Therefore, some foods heated in a microwave oven can have a less-attractive appearance, blander taste, and they may be less thoroughly cooked, than if they had been prepared in a regular electric or gas oven.

Microwave Oven Concerns

From a health standpoint, be aware that many microwave ovens can sooner or later emit potentially harmful microwave radiation (radar) into the kitchen. This can happen as a result of slamming the oven’s door, simple wear and tear, manufacturing defects, or because of a build up of food particles around the door seals.


Microwave Ovens and Health

According to the FDA:


Much research is under way on microwaves and how they might affect the human body. It is known that microwave radiation can heat body tissue the same way it heats food. Exposure to high levels of microwaves can cause a painful burn. The lens of the eye is particularly sensitive to intense heat, and exposure to high levels of microwaves can cause cataracts. Likewise, the testes are very sensitive to changes in temperature. Accidental exposure to high levels of microwave energy can alter or kill sperm, producing temporary sterility. But these types of injuries - burns, cataracts, temporary sterility - can only be caused by exposure to large amounts of microwave radiation, much more than the 5mW limit for microwave oven leakage.

Less is known about what happens to people exposed to low levels of microwaves. Controlled, long-term studies involving large numbers of people have not been conducted to assess the impact of low level microwave energy on humans. Much research has been done with experimental animals, but it is difficult to translate the effects of microwaves on animals to possible effects on humans. For one thing, there are differences in the way animals and humans absorb microwaves. For another, experimental conditions can't exactly simulate the conditions under which people use microwave ovens. However, these studies do help us better understand the possible effects of radiation.

Currently, the U.S. Bureau of Radiological Health has set a permissible leakage level of 5 milliwatts per each square centimeter of surface area (which is the same as saying 5 mW/cm2) at a distance of 5 centimeters from the oven’s surface. While there is apparently no direct correlation between using microwave ovens and ill health yet documented, there are concerns that further research should address. For example, microwave exposure from sources other than microwave ovens (like radar installations) has led to certain health problems including cataracts and perhaps even cancer.


If you’re in the market to purchase a microwave oven, it would be wise to choose a sturdily constructed model with a tight-sealing door. Before purchasing a unit, you might want to check the current consumer guides in magazines or on the Internet for the models with the highest safety ratings. 


When your microwave oven is operating at home, some experts recommend that you stand at least three feet away from it as a safety measure. This is because microwave levels drop off quickly just a short distance from their source.


As many people are aware, the cookware you use in a microwave oven is also important. When possible, use cookware made of glass or ceramic, rather than plastic, because those materials are more stable when subjected to cooking temperatures. Heated plastic can give off bothersome odors and give a “plasticky” taste to the cooking food, and eating plastic-infused food which may include potentially harmful substances such as phthalates simply can’t be a good nutrition choice.


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Microwave Ovens - Safe?:  Created on February 19th, 2011.  Last Modified on August 15th, 2011


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