Microwaves​—How Dangerous Are They?

IT HAS long been known that just as microwaves in an oven can cook beef, they can also cook human tissue. This will occur if exposure is at high enough intensities, for a long enough period of time, and at certain particularly penetrating frequencies.

For example, the lens of the eye is particularly sensitive to heat because it lacks an efficient circulatory system to cool it. Excessive heat from microwaves can therefore cook the lens protein of the eye in the same way it coagulates egg white.

Also especially sensitive to thermal damage from high levels of microwaves are the stomach, intestines and bladder. This is true, too, of the testes, since sperm can be formed only at temperatures lower than that of the body itself. High doses of microwaves can lead to death, painful burns, blindness, sterility and gastrointestinal problems.

Measuring Microwaves

Scientists measure microwaves according to their power densities, that is, the amount of energy flowing each second through a measure of space. Western scientists believed that serious injuries due to heating could be caused only at power densities of 100 milliwatts (100,000 microwatts) per square centimeter or higher. It was theorized that one tenth of that figure, or 10 milliwatts (10,000 microwatts) per square centimeter, should be a safe figure. Thus a recommended occupational safety standard of 10,000 microwatts per square centimeter was adopted in the United States in the mid-1950’s. With slight modifications the standard was also accepted by Canada, the United Kingdom, the Federal Republic of Germany, the Netherlands, France and Sweden.

In 1971, the standard for allowable leakage from microwave ovens in the United States was set by law at 1,000 microwatts per square centimeter at a distance of five centimeters (2 inches) at the time of sale of the oven, and 5,000 microwatts per square centimeter during the life of the product. These standards were based on the belief that the only danger from microwave exposure was at high intensities that could cause overheating.

Research from the Soviet Union

While Western scientists studied the heating effects of high-intensity levels of microwaves, Russian and Eastern European countries began reporting on the cumulative effects of chronic exposure to low levels of microwaves, levels considered safe in the West. The Soviet Union in particular pioneered research in this area, beginning to study the question in the 1930’s.

The Soviet researchers found that microwaves not only could cause damage due to overheating but could also result in effects that could not be explained by heating alone. And these effects could be seen at exposure levels at and below 10,000 microwatts per square centimeter, the recommended occupational safety standard in the U.S. The Soviets concluded that the Western safety standard, which was based solely on considerations of heating effects, was too high for safety, away too high.

Thus the Soviet Union, as well as other European countries, established strict guidelines for the protection of microwave workers. For example, the Soviet on-the-job standard is 10 microwatts for an eight-hour day, or up to 100 microwatts for two hours, whereas the U.S. standard permits exposure to 10,000 microwatts! Russian workers are required to wear protective goggles any time they are temporarily exposed to a microwave radiation level of 1,000 microwatts per square centimeter, the level routinely allowed to leak from U.S. microwave ovens. And in Poland pregnant women are not allowed to be occupationally exposed to microwaves because of fear of birth defects.

For years, research studies from these countries have shown functional changes in the nervous, cardiovascular and blood systems of people due to exposure to very low levels of microwave radiation. They call it “microwave sickness,” which they accept as a distinct clinical entity. The symptoms of this sickness can include headaches, eye pain, irritability, dizziness, anxiety, emotional instability, disturbed sleep, fatigue, depression, forgetfulness, decreased efficiency, loss of appetite, an inability to concentrate, cardiovascular changes such as slowed or irregular heartbeat, hair loss, changes in blood pressure, enlargement of the thyroid gland, depressed endocrine function, increased susceptibility to infectious disease, palpitations, breathlessness and tremors in the arms and legs.

Animal experiments with low levels of microwaves confirm potential hazards. These studies have found that exposure to low levels of microwaves decreased physical endurance and retarded weight gain, resulted in altered blood pressure and heart rates, altered immune reactions, reduced secretion of gastric juices, and caused fetal deaths and serious birth defects.

Western Countries Reexamining Standards

These reports generally were discounted in the West until the mid-1970’s. At that time the United States began a systematic effort to duplicate the Soviet and Eastern European experiments to determine whether their 10,000-microwatt safety standard was reasonable or not and to see if they could find the same low-level effects their Eastern counterparts said they had found.

While not all the research is completed, enough corroboration has now been reported to cause a serious questioning of the safety of Western standards. A number of countries, such as Sweden, have recently stiffened their standards, and others are considering following suit. The U.S. is expected to issue tougher standards soon.

The New York Times of February 26, 1980, carried the heading “Microwave Threat Stalls Trade Center TV Tower.” The article illustrated the controversy over microwave safety standards, observing:

“The concern is for the 1.5 million people who visit the observation deck on the second tower . . . and for the office workers who would occupy its top nine floors . . .

“The Port Authority’s task has been complicated by the division within the scientific community over what constitutes an acceptable level of microwave transmissions. As a result, no Federal or city standards have yet been set for such cases.

“Tests in recent weeks have shown that the top floors would be subject to more than 360 microwatts​—or 360 millionths of a watt—​of microwave pressure per square centimeter . . . A diplomatic furor of sorts resulted two years ago when American Embassy personnel in Moscow protested that Soviet eavesdropping equipment had been subjecting them to up to 18 microwatts.

“The Occupational Safety and Health Administration has recommended that industrial workers be exposed to no more than 10,000 microwatts, but several Federal agencies are studying the issue and both Government and private scientists expect the standards, especially for exposure by the public, will be set much lower.”

The article went on to mention a scientist who recommended that maximum public exposure be reduced below 100 microwatts, and another who recommended it be set below 50 microwatts.

Several American laboratories have reported effects on people of low-level exposure to microwaves. Some of their findings, along with other information on the effects of exposure to microwaves, are presented on the opposite page under the heading “What Scientists Are Finding.” The items bear careful examination.

What Does It All Mean?

There is considerable controversy as to how these experimental results should be interpreted. However, one thing is now sure: there is a nonthermal effect from microwaves on both animals and man at levels that at one time were considered insignificant in Western countries. Of concern is the fact that these are levels that a substantial fraction of the world’s population may already be exposed to every day.

The controversy arises from the question of the degree of danger that this nonthermal effect represents. Some scientists point out that there is a great difference between a biological effect and a biological hazard. That is, low levels of microwaves can be seen to have an effect on both animals and man; for example, in a reduction in the ability to perform tasks. But how serious is this effect?

“No one,” a U.S. government spokesman has pointed out, “should expose himself to any unneeded radiation. The problem is that so much of the radiation people are exposed to​—microwave ovens, television transmitters, and what have you—​are all devices that are doing very useful things that people want to do and want done for them.”

Yet are the risks of longtime exposure to low levels of microwaves really dangerous? Russian and Eastern European scientists who have studied this question considerably longer than Western scientists are already of the opinion that the effects of low-level exposure to microwaves are cumulative. Furthermore, they believe these effects may not be reversible if exposure persists longer than two to six years.

Now there are also American scientists who are very concerned about the potential hazards of microwaves. “The population risk is not really known,” admits a U.S. government report on microwaves. “It may be special groups; it may well be the entire population.” The American scientist who first proposed 10,000 microwatts as a safe occupational standard in the 1950’s has since admitted that it “badly needs refinement,” having been “crudely set.”

Dr. Milton M. Zaret, a professor of ophthalmology at the New York University Bellevue Medical Center, who has long been a student of the biological effects of microwaves, warns: “The dangers cannot be overstated because most non-ionizing radiational injuries occur covertly, usually do not become manifest until after latent periods of years, and when they do become manifest, the effects are seldom recognized.”

So what are safe levels of exposure to microwaves? “I have no idea what a safe level is,” Zaret himself admits. “I don’t think anyone in the world knows what a safe level is.”

Wisely, then, care should be exercised when a person is near sources of microwave emissions, a matter that a future issue of Awake! will consider further.

[Box on page 15]

WHAT SCIENTISTS ARE FINDING

● The U.S. Navy states that “exposure of Naval personnel to microwave radiation is an acute problem” and that “even low doses are likely to reduce the efficiency of personnel in vital duty positions.”

● In one U.S. Navy study, the human volunteers showed a significant decline in their ability to perform simple addition, when exposed to low levels of microwaves.

● Rats in one study were trained to push levers to get food. After six months of training, they were able to push the levers correctly 80 percent of the time. They were then exposed to microwaves at 5,000, 10,000 and 15,000 microwatts per square centimeter for 30 minutes. Their ability to push the levers successfully was reduced to below 50 percent. When the microwave exposure ended, they could again complete the lever test at their former efficiency.

● Johns Hopkins University in the U.S. has researched the question as to whether there is a link between microwave radiation and cancer in man. There are some who believe that it could turn out to be so. Dr. James M. Sontag of the National Cancer Institute at Bethesda, Maryland, says: “I wouldn’t scoff at the possibility. It’s true that microwaves are non-ionizing and therefore supposedly not carcinogenic. But ultraviolet light is also non-ionizing and it can cause cancer,” he points out. “That’s the way people get skin cancer.”

● Professor Carpenter of Tufts University wrote: “We have clearly demonstrated a cumulative harmful effect of microwave radiation on the eye, so that single exposures to radiation which are not of themselves harmful may become truly hazardous if they are repeated sufficiently often.”

● A number of veterans of the U.S. armed forces have filed disability claims, alleging that they suffered cataracts and other lens defects as a result of chronic exposure to low-level microwaves (from 1,000 to 10,000 microwatts per square centimeter) while in the service. Some of the claims were rejected, but several have been settled in favor of the veterans.

● “At the New York ‘Times,’ two copy editors working with VDT’s​—Video Display Terminals—​have developed cataracts at remarkably early ages (29 and 35),” reports “New Times” of March 6, 1978.

● Nonionizing radiation exposure has been shown to alter brain electrical activity.

● In a U.S. Navy experiment using human volunteers, blood-serum triglyceride levels rose to abnormally high levels in 9 out of 10 volunteers following one day of exposure to an extremely low-frequency magnetic field.

● A bulletin issued by the U.S. Air Force states that “epigastric distress and/​or nausea may occasionally occur at as low as five to ten milliwatts per square centimetre.”

[Picture on page 13]

The 351.5-foot TV tower atop the World Trade Center​—a microwave danger?