How Safe Are Microwave Ovens?
“NO ONE knows whether or not they’re safe over a long period of use,” stated Consumers Union, a product-testing organization, about United States microwave ovens.
Some microwave scientists own microwave ovens and they feel they present no serious dangers. Others feel that they do. Dr. Milton M. Zaret explains:
“The microwave-oven-leakage standard set by the Bureau of Radiological Health is approximately one billion times higher than the total, entire microwave spectrum given off by the sun. It is appalling for these ovens to be permitted to leak at all, let alone for the oven advertisements to encourage our children to have fun by learning to cook with them.”
Certain questions about the safety of microwave ovens have yet to be answered. In the meantime, some things are known that indicate who are most likely to be sensitive to low-level microwave exposure.
Those at Greatest Risk
Pregnant women especially have reason for caution. According to a U.S. government agency, the human fetus is “probably the most sensitive segment of the population potentially exposed to microwave radiation.” In Czechoslovakia and Poland, pregnant women are singled out for special protection in the work place for fear of miscarriages and birth defects. In neither of these countries are pregnant women permitted to be exposed to the amounts of microwave radiation that are allowed to leak from ovens sold in Western countries.
Children represent another sensitive segment of the population. “The possibility that cumulative effects of microwave radiation can occur has been raised through research and cannot be ignored,” says a U.S. Bureau of Radiological Health report. “The potential exists for exposure of young and very young people repetitively as [microwave] ovens come into common usage and effects may result.”
In addition, some Soviet investigators recommend that people with cardiovascular problems avoid low-level microwave exposures because of the possibility of heart attacks. They also say that the chronically sick and those who have infectious diseases or have recently been weakened by them are more sensitive to the effects of microwave exposure.
Levels of Exposure
In the United States the allowable leakage of a microwave oven at the time of sale is 1,000 microwatts per square centimeter at a distance of five centimeters (two inches), and 5,000 microwatts per square centimeter thereafter. However, as one moves away from a microwave oven, the level of exposure drops dramatically. Dr. M. Shore, director of the division of biological effects at the Federal Department of Agriculture’s Bureau of Radiological Health, explains:
“One characteristic of microwaves is that, as you move away from a source, such as an oven, the levels fall off very substantially. If you step back 2 inches (where the five milliwatts [5,000 microwatts] are measured) to 20 inches, or roughly an arm’s length, you’ve moved back by a factor of 10, but the microwave level drops by a factor of 100, or the square of the distance. The net effect is that the exposure level possible to consumers using microwave ovens in the home is probably less than is permissible under the Russian occupational standard.”
But this may not necessarily be the case. In the Soviet Union the on-the-job maximum allowable exposure to microwaves is 10 microwatts per square centimeter for an eight-hour day. Thus the 5,000 microwatts per square centimeter allowed to leak from ovens in the United States may well expose a person near a leaking oven to more radiation than Soviet standards allow.
A 1969 survey in the United States showed that a startling one third of the microwave ovens tested leaked in excess of 10,000 microwatts per square centimeter. More recent models evidently are not so prone to leak radiation. But how can a person know how much his oven is leaking? It must be checked with appropriate instruments. So if you have an older oven it would seem to be a good idea to arrange for a qualified serviceman to check it.
Matter of Concern
But are ovens that leak the allowable levels of radiation safe? Czech scientists have reported some effects of microwave exposure at power densities as low as 100 microwatts per square centimeter. That is about the level of radiation that an oven leaking 5,000 microwatts per square centimeter at two inches would expose one to at an arm’s length. Further, they are of the opinion, as are Russian scientists, that microwave effects are cumulative. Therefore, a low-level dose the first day, which in itself would not be enough to affect you, is added to a low-level dose the next day and the next, and so on, and eventually effects can be seen.
The director of the U.S. Bureau of Radiological Health has admitted that the advance of microwave technology in the West has “far exceeded” research into the potential risks. “Although the Bureau has promulgated a performance standard for microwave ovens,” he said, “a great deal of research is required to assess the differences of opinion related to low-level exposures to microwaves.”
Since no one can say with certainty what levels of exposure to microwaves are safe, it is the course of wisdom to use a microwave oven with great care. Following the accompanying safety tips can be a protection.
□ Do not attempt to operate a microwave oven with an object caught in the door, a door that does not close firmly, a door that is bent or damaged, or an oven with broken hinges or latches, or a cracked sealing surface.
□ Wash frequently with water and mild detergent. Never use scouring pads, steel wool or other abrasives.
□ Don’t insert any objects around the door seal. Even a tiny opening around the door, no more than that caused by a piece of paper towel in the door or a buildup of grease around a door seal, can result in sharply increased leakage.
□ Never inactivate or interfere with the oven safety interlocks, the devices that turn ovens off automatically as the door is opened (required on all ovens manufactured in the U.S. after 1971). Surveys have shown that maladjustment of oven-door safety interlocks has been a frequent cause of microwave leakage.
□ Never operate the oven when it is empty.
□ Stay at least an arm’s length away from the front of an operating oven. Never stand gazing into a working oven, and do not allow a child to do so either.
□ Do not use microwave ovens for canning.
Following these tips in no way guarantees safety, since at present it is not known if microwave ovens can be judged entirely free of radiation hazards. However, following these suggestions should help to minimize exposure levels and serious accidents.
When it comes to microwave ovens, you must use them at your own risk.