No Obvious Danger Has Boiled Out Of Microwaves

August 23, 1987|By Phil Vettel.

Q-We are the only ones on the block who do not yet own a microwave oven. How safe do the experts say they are in terms of radiation exposure? We have three growing children, and we`d hate to expose them to a danger that, in 20 or 30 years, might take the form of disease. Or is ``the jury still out`` as to the consequences of long-term use?

A-I can`t, of course, tell you which of today`s beliefs will be discredited in the next 30 years. But going by today`s scientific evidence, which is all we have, after all, there`s no reason to postpone that microwave purchase if safety concerns are all that is holding you back.

Take what solace you may in the knowledge that if it turns out that a microwave oven has doomed you to an early grave, you`ll have lots of company when you arrive. The Association of Home Appliance Manufacturers reports that about two-thirds of all U.S. households own at least one microwave oven. So you may be the only one in town, let alone your block, to not own a microwave. Manufacturers shipped more than 12 million units to the U.S. market in 1986. Obviously a great many buyers are confident that microwave ovens are safe.

One reason may be that the manufacture of microwave ovens is subject to several pounds of federal regulations. They basically assure that, barring serious defect, to hurt yourself with a microwave (apart from dropping one on your foot), you just about have to try.

The primary concern, of course, is the eminently reasonable fear of exposure to microwave radiation. Many people think of radiation exposure as something that results in long-term health impairments. The main danger from microwaves appears to be more immediate. Simply put, microwave radiation can do to you what it does to a leg of veal-burn it severely, damaging flesh and nerves. Consequently, the bulk of the federal regulations ensure that very little radiation escapes from an operating microwave oven.

For instance, federal standards require that microwave ovens have two safety interlocks that turn off the oven whenever the door is opened. The first interlock is the main one; the second is a backup that will disable the unit, usually by blowing the fuse, if the first interlock fails.

There also are very strict limits on radiation leakage. At the time of manufacture, no microwave can leak more than 1 milliwatt per square centimeter. Once the unit is purchased, the limit rises to 5 milliwatts per square centimeter, but that higher limit applies throughout the life of an oven. At no time can it ever exceed that limit.

Okay, you ask, how much is 5 milliwatts per square centimeter? To put it in perspective, an appliance association engineer says that though it`s known that microwave radiation has caused cataracts in laboratory animals, it took long-term exposure to levels approaching 150 milliwatts per square centimeter. ``It takes a lot of energy to cause cataracts,`` the engineer said. ``And the government requirements are considerably below any level known to cause harm; there`s a tremendous safety factor built in.``

The Center for Devices and Radiological Health in Washington, D.C., has the task of checking microwave manufacturers. They do this by inspecting manufacturing plants, examining test records that all manufacturers must keep and looking for potential problems. They also test selected models at a Food and Drug Administration laboratory, looking for defects caused by short-term and long-term use.

If you suspect (and I`m not sure why you would) that your microwave is leaking excessive amounts of radiation, contact the manufacturer. A service person can check radiation levels; there is really no way for an owner to do so. The FDA, which oversees the center, once had a field program for testing microwave ovens in people`s homes. It was discontinued, said a regulatory officer at the center, because investigators didn`t find enough problems to make the program worthwhile.

Here is more good news; radiation leakage limits refer to the amount of radiation measured 2 inches from the oven. Who stands 2 inches away from the microwave? Twenty inches is more like it; microwave radiation dissipates so rapidly that, relative to the location of an oven, the radiation level at 20 inches is just 1 percent of the radiation at 2 inches.

``As a general precaution,`` the regulatory officer said, ``we advise people not to lean against a microwave oven while it`s operating. But we don`t even know of any hazard they`d be exposed to from doing that.``

This is not to say that no one is looking into the possibility of adverse long-term effects from microwave exposure. To the contrary, research continues in several quarters on long-term effects of microwave ovens, and even though nothing scary has turned up yet, scientists keep looking. In that sense, you could say the jury is still out on microwaves, and I suppose it always will be.

Note: A couple of weeks ago I wrote about the nasty habit spiders have of spinning nesting webs in the venturi tubes of gas barbecue grills, causing gas-flow interference and related problems. Well, guess what-someone has devised a flexible-wire brush designed specifically to clean spider webs out of venturi tubes. It`s called the Ladyfingers, it`s made by Brushtech Inc. in Plattsburgh, N.Y., it retails for about $4, and it`s carried locally by Collins Fireplace and Patio Shop in Wheeling. No doubt it will be available in more places by spring.

Readers may submit questions of general interest to As a Matter of Fact, care of Tempo, The Chicago Tribune, 435 N. Michigan Ave., Chicago, Ill. 60611. Unpublished letters cannot be answered individually.