How safe are microwave ovens?

The microwave oven has become more and more a common household feature. People are lured by the convenience it offers. Or by the social status it suggests. But as they welcome this ultra-modern device into their homes, many are secretly frightened by rumors of hazards that it supposedly poses to human health. How safe really are microwave ovens?

Microwave ovens use a form of electromagnetic radiation to cook food. An electron tube, called a magnetron, produces radiation in the oven interior that penetrates or gets absorbed by the food. The radiation causes the food water molecules to vibrate, producing heat that cooks the food. Foods that are high in water content, like fresh vegetables, cook more quickly than foods that are relatively drier.

Much research is underway on how microwave radiation might affect the human body. As a general principle, microwaves are potentially hazardous. But the extent of the damage, if ever damage occurs, depends on the gravity of the radiation exposure. It is known that microwave can heat body tissue the same way it heats food. Exposure to high levels of microwave radiation can cause a painful burn.

Particularly at risk is the lens of the eye, which is highly sensitive to intense heat. High exposure to microwaves can cause cataracts. Among males, the testes are very sensitive to changes in temperature. Exposure to high levels of microwave energy can mutate or kill sperm and cause sterility but often only temporarily. The thing to note, however, is that these possible injuries can be caused only by high microwave radiation, in amounts much greater than can possibly leak out from a microwave oven.

So far, the reported injuries from microwave ovens are limited to the type that could happen with any oven or cooking instrument. For example, people have been burned by hot food, splattering grease, or steam from food cooked in a microwave oven. But these injuries may have been caused mainly by carelessness and not by microwave radiation.

Some serious skin burns or scalding injuries around people's hands and faces have also been reported as a result of hot water erupting out of the cup after it had been over-heated in a microwave oven. These reports are probably true, since microwaves are capable of heating water way past its normal boiling point. Upon slight movement or when foreign materials such as instant coffee or sugar or a spoon is put into superheated water, the water may leap out of the cup.

Concern has also been expressed over the possibility that leakage from a microwave oven may interfere with electronic cardiac pacemakers. Similar concern was also aired about pacemaker interference from electric shavers, auto ignition systems, remote controls of home appliances, and other electronic products. There are many other products that could possibly cause this problem.

New models of microwave ovens, those made after October 1971, pass through strict radiation safety tests before they reach the stores. The maximum radiation leakage allowable is far below the level known to cause harm to people. It is safe, although not advisable, to be around two feet distance from the microwave oven when in use. But there is no reason to stay that close to the oven since the cooking time can be set automatically.

Manufacturers are closely monitored by both government authorities and consumer groups. They are required to design their microwave ovens with two independent interlock systems that automatically turn the appliance off the moment the latch is released or the door opened. The noise that sometimes prevails shortly after the door opens is usually just the fan. No residual radiation remains after the oven is off.

Microwave cooking can be more energy efficient than conventional cooking. Foods cook faster in the microwave oven since the energy heats only the food, not the oven compartment. Microwave cooking does not reduce the nutritional value of foods any more than conventional cooking. In fact, the foods may keep more of their vitamins and minerals, because microwave cooking is quick and does not require adding water.

A considerable margin of safety is already built into microwave ovens. However, it is still up to the user to operate the machine properly. The manufacturer's operating instructions must be studied beforehand and followed accordingly. Small children shall not be left on their own to operate the microwave oven-or, for that matter, any sophisticated appliance. With reasonable care and precaution, the microwave oven is as safe to use as the ordinary television set.