Are microwave ovens safe?

The magnetron -- a device which produces microwaves -- was developed during World War II for use in radar systems. One of the engineers was Percy Spencer, who worked for Raytheon. Toward the closing days of the war, Spencer noticed that an active radar set had melted a chocolate bar in his pocket. Shortly afterward, he created the first batch of microwaved popcorn.

During the war, there were many third-hand anecdotes (usually derided) about servicemen at radar stations using the radar sets to cook food. Quite a few web sites allege that the Nazis experimented with a device called the radiomissor, an alleged transportable microwave oven designed to feed troops in the field. Was Spencer's "chocolate bar" tale concocted to hide the fact that Raytheon -- a company looking for a good post-war consumer product -- stole the idea for the microwave oven from captured German documents? It's an intriguing theory, but it has one huge problem: All of the web sites which discuss the radiomissor suffer from a strange refusal to cite evidence. I've read any number of books about World War II and the Third Reich; none of them mention such a device.

After the war, Raytheon marketed the "Radarange." The first version cost roughly $5000 and were nearly six feet tall. These early devices used radar-quality magnetrons, which made them much more powerful than the tabletop models in use today. Roughly two decades passed before the company realized that consumers didn't need such extreme levels of power.

The microwave oven did not catch on until the late 1960s, when relatively inexpensive countertop models came out. Today, nearly 90 percent of American homes have these heating devices. Most people use them for reheating, defrosting, or cooking packaged foods.

Despite the ubiquity of Spencer's creation, many people still regard it warily. The microwave oven has, over the years, given rise to any number of rumors and scare-stories. Most of them have little basis in fact.

A number of internet sites will tell you that Russia banned microwave ovens in 1976 -- and yet these web authors always offer this claim without footnotes and without any hyperlink to a reliable source. The Wikipedia discussion here offers convincing details about the types of microwave ovens produced in Russia during the 1980s -- including model numbers and the names of the factories where the product was manufactured.

(If the former Soviet Union really had banned microwave ovens in 1976, Western propagandists would have discussed the matter endlessly in the 1980s and late 1970s. They didn't. Similarly, Soviet propagandists would have scored the U.S. for promoting a dangerous device. They didn't.)

This video examines some of the more bizarre claims about microwave oven dangers. In this case, many of the more extreme claims were traced to a bizarre religious cultist lacking any knowledge of science.

This skeptical website counters the claims made in one of those all-too-familiar viral emails (a common method of spreading fear-stories). The email, titled "Ten Reasons to Throw Out Your Microwave Oven," makes the following claims:

1. Continually eating food processed from a microwave oven causes long term — permanent — brain damage by "shorting out" electrical impulses in the brain, de-polarizing or de-magnetizing the brain tissue.

2. The human body cannot metabolize the unknown byproducts created in microwaved food.

3. Male and female hormone production is shut down and/or altered by continually eating microwaved foods.

4. The effects of microwaved food by-products are permanent within the human body.

5. Minerals, vitamins, and nutrients of all microwaved food is reduced or altered so that the human body gets little or no benefit, or the human body absorbs altered compounds that cannot be broken down.

6. The minerals in vegetables are altered into cancerous free radicals when cooked in microwave ovens.

7. Microwaved foods cause stomach and intestinal cancer tumors. This may explain the rapidly increased rate of colon cancer in America.

8. The prolonged eating of microwaved foods causes cancerous cells to increase in human blood.

9. Continual ingestion of microwaved food causes immune system deficiencies through lymph gland and blood serum alterations.

10. Eating microwaved food causes loss of memory, concentration, emotional instability, and a decrease of intelligence.

None of these claims are true. The author of the chain letter cites not single piece of scientific research. Apparently, this viral email stems from the same religious cult mentioned above.

The Snopes rumor-control web site tested the bizarre claim that microwaved water will kill plants. The assertion is a provable lie. (Prove it yourself by conducting your own experiment.)

Snopes also disproved the commonly-heard assertion that microwaving plastic food containers will release dangerous toxins. Actually, any form of heat -- not just microwave heating -- increases the possibility of releasing chemicals from plastic materials. That doesn't mean that you are necessarily in danger is you use a plastic spoon to stir chili, since certain types of plastics are designed for cookware.

Other fear-mongers claim that microwaved food carries dangerous "riolytic compounds" -- a silly assertion. Radiolysis occurs under ionizing radiation; microwaves are a form of non-ionizing radiation, as are sound waves and visible light. Conventional ovens also use non-ionizing radiation. So does your fireplace.

Ionizing radiation removes electrons from atoms; the freed electrons are called ions. X-rays and gamma rays are examples of ionizing radiation.

Microwave urban legends have been around since the microwave oven first became popular, back in the days of Vietnam and Haight-Ashbury. But these claims have yet to give rise to a lawsuit. We live in a society where (as Geraldine Ferraro once pointed out) you can sue someone over a ham sandwich. If firm scientific evidence existed linking microwaved food to brain damage, someone probably would have brought the matter to court by this point.

Some websites claim that the American microwave industry has successfully covered up the dangers -- and that this cover-up has, by some miracle, extended to every country in the world. We are even supposed to believe that American corporate pressure kept the dangers unpublished and un-discussed by the scientific establishment in every nation of the former Soviet bloc. A ludicrous proposition.

Consumer Reports magazine, run by the well-respected Consumers Union, operates outside of corporate pressure. Techs hired by Consumer Union found that "microwave-cooked food may retain vitamins and minerals better than stove-top-cooked food because the microwave zaps food quickly and without much water."

Scare stories aside, are there any legitimate reasons to be concerned about microwave ovens?

The more reasonable arguments against these devices involve the possibility of oven radiation leakage. Microwaves can zap your body organs -- say, your eyeballs -- the same way they heat food. At one time, there was a great deal of controversy about whether radar operators were particularly susceptible to cataracts. The consensus now is that avionic radars have caused eye damage. In 1990, a police officer named Gary Poynter published research indicating that police radar exposure might cause cancer -- a claim disputed by subsequent researchers and the FDA.

Conceivably, a microwave oven with poor shielding, placed at eye level, might -- over a long period of time -- cause cataracts. The age of the device is a key factor:

Manufacturers must adhere to strict guidelines in microwave production to ensure that they have a tight seal and do not emit dangerous levels of radiation. However, many homes contain older microwave ovens that may not perform to current standards.

Research conducted by microwave repair servicemen indicates that over 50% of microwaves which are at least two years old leak around 10% higher radiation levels than what is recommended by the FDA. The good news is that by doing a slight readjustment, the problem can be solved. If you do have a microwave that more than two years old, have it serviced to see whether it is safe to use.

There have been controversial studies indicating that other forms of non-ionizing radiation (such as the electromagnetic fields created by power lines) may have deleterious health effects. But if you eat a microwaved hot dog, you aren't any likelier to get brain cancer than if you eat a boiled hot dog.

Of course, the boiled wiener will probably taste better.