Nonionizing Radiation: Unsung Villain?

This essay is reproduced here as it appeared in the print edition of the original Science for the People magazine. These web-formatted archives are preserved complete with typographical errors and available for reference and educational and activist use. Scanned PDFs of the back issues can be browsed by headline at the website for the 2014 SftP conference held at UMass-Amherst. For more information or to support the project, email

Nonionizing Radiation: Unsung Villain?

by Ross Flewelling

‘Science for the People’ Vol. 12, No. 2, March-April 1980, p. 32-38

Ross Flewelling is a member of the East Bay Science for the People, a worker in the Department of Physics at the University of California, Berkeley, and a longtime student of illogical positivism. He acknowledges many useful comments on this article by members of the East Bay SftP.

All of us … everywhere, right now … are immersed in a sea of nonionizing electromagnetic radiation. From AM, FM and CB radio transmissions, to radar and microwave relay tower emissions, to medical diathermy and electrosurgical units in hospitals, to the prolific industrial and military uses — nonionizing radiation incessantly invades our lives. 

The sun naturally bathes us in such radiation. But today artificial sources creates levels a million to a billion times higher than natural ones, and increasingly evidence reveals that such radiation poses significant health and environmental hazards. The National Institute of Occupational Safety and Health estimates that about 20 percent of the industrial work force is exposed to some 35 million radio frequency sources. Recent measurements show that the vast majority of this working population is exposed to dangerously high levels. 

Ionizing radiation (especially in its relation to nuclear weapons and power) has stimulated a great deal of public concern over the last several decades. Mounting political struggles have revealed not only grave public and workplace dangers, but also the intimate intermingling of government, military, and corporate interests. There is every reason to believe that these same revelations will be mirrored in the rising concerns over nonionizing radiation in the decade ahead; it is already an issue of economic and political importance. 

Pervasion of Uses 

The wild proliferation in uses of nonionizing radiation is due to four fundamental properties: it is fast, it is penetrating, it carries and delivers energy, and it has been presumed safe. 

Because microwaves and radio waves travel at the speed of light (nothing travels faster) they are ideal for long-range detection and communication. Electromagnetic waves were first shown to exist when the German physicist Heinrich Hertz in 1888 produced an electric spark in a device and detected it almost instantaneously across the room. By 1901 Guglielmo Marconi sent a message across the English Channel by wireless telegraphy, and by 1933 radio detection and ranging (radar) rapidly spurred the development of radio technologies because of its great usefulness in warfare. 

In the 1890s a second major branch of applications developed, taking advantage of other fundamental properties: penetration and energy transport. Nikola Tesla, J.A. d’Arson val and others noted that radio waves and mocrowaves penetrate deep into biological materials and simultaneously heat tissues through, suggesting various medical uses: for “diathermy” (literally, “heating through”) in heat therapy and for “Bovie” surgical units which instantaneously cut and cauterize human flesh. These two properties — penetration and heating — have also led to widespread uses of nonionizing radiation in industry for heating, gluing, sealing, heat tempering and much more. 

Table 1 summarizes many of the common uses of microwave and radio wave radiation, most of which exploit the properties of detection and communication or of penetrative heating and energy transport. 

Natural microwave and radio wave radiation is emitted by the sun and by electrical activity in the atmosphere. However, the ubiquitous use of electronic technologies in this century has given rise to an artificial radiation bath which increases the exposure over natural background of the general population by a factor of more than a million, and of some particular populations by a factor of more than a billion. Such proliferation was based on a belief that nonionizing radiation was harmless — a belief rooted in ignorance. 

Biological Effects 

The very factors which make electromagnetic radiation useful also make it dangerous. Since it is invisible we are not aware of being irradiated; yet the radiation penetrates deep into our biological tissue. As the radiation interacts with the tissue, biological molecules are set into rapid motion as they absorb the energy of the radiation. Thus the primary mechanism for the interaction of nonionizing radiation with biological systems is the thermal effect of heating up the body. That is exactly why microwave ovens cook food.




Military: 20 million radar and microwave sources (1975). 

Industrial: 35 million sources, exposing about 20 percent of the work force (1980). 

Communications: 30 million Citizen Band radios (1979), 120,000 microwave communications towers (1972), 15,000 shortwave transmitters (1972). 

Other: 10 million microwave ovens (1979), 15,000 diathermy units with about 2 million people treated annually (1972), 40,000 circuit miles of overhead extra-high voltage AC electric transmission lines (1972). 



Food: Drying, heating, sterilization in industrial food processing. 

Forest Products: Hardwood and paper drying, destruction of fungus and wood worm. 

Mining: Curing and breakdown of concrete, heating of oil shale. 

Chemical: Plasma chemistry processes, curing of resins and rubber products, sealing of plastics. 

Agriculture: Treatment of seeds, destruction of insects, protection of plants against frost, drying of grain.

Other Industrial: Drying of match heads, film and leather; manufacture of drugs; melting of explosives; repair of asphalt pavements. 


Medicine: Diathermy, electrosurgical units, blood warming, thawing of frozen tissue, diagnostic microwave techniques. 

Scientific: Microwave and radiowave sources, plasma heating,particle accelerators. 

Home and Community: Microwave ovens, shoplifting detectors, burglar alarm systems, garage door openers, automobile speed detectors, toys. 

Energy Transmission: Power line radiation, Satellite Power System microwave transmission. 

Communications: Satellite communications, radar, microwave relay, radionavigation, radio and TV communication. 

Source: Taken in part from J .M. Osepchuk in Fundamental and Applied Aspects of Nonionizing Radiation, S. Michaelson et al., eds. (New York: Plenum Press, 1975), p.419. 




Biological Effect Test Animal  Min. Effect Level (mW/ cm2)
Severe thermal stress/death Human (1 hr)  

Rat, Mice (140 min)



Cataract formation/eye damage Rabbit (Human)a  80-100
Testicular damage  Rabbit (Human)  5-10
Altered neuron firing Rat, Aplysia  5-10
Altered action of drugs Rat, Mice 5
Altered metabolism function  Rabbit 5
Altered thyroid function Rabbit  5
Neurotransmitter release in brain  Rabbit, Guinea pig .5-25
Cerebral calcium flux changes Cat, Chickb  .5-1
Behavioral modifications  Rat, Monkey .15-5
Behavioral and cardiovascular changes Humanc .01

 a. Experiments were carried out on rabbits, but the levels given are those estimated for the human population. 

b. Effects at these low levels were only noted when the fields were modulated at extremely low frequencies. 

c. Results of Soviet and East European studies, regarded as controversial in the United States. 

Data are taken from a variety of sources. Especially good references are S. Baranski and P. Czerski, Biological Effects of Microwaves (Stroudsbury, Pa.: Dowden, Hutchinson & Ross, Inc., 1976), and S.F. Cleary, “Survey of Microwave and Radiofrequency Biological Effects and Mechanisms,” in The Physical Basis of Electromagnetic Interactions with Biological Systems, HEW (FDA) 78-8055, 1978. 


The biologic effect of such heating is to create thermal stress in the whole body, or parts of it. The first several listings of Table 2 are examples of some biological consequences of heating. At extremely high exposure levels (above 100 mW/cm2) the human body will suffer severe thermal stress (hyperthermia and hyperpyrexia) which, if prolonged, can result in death. Exposed to these high levels even for a very short time, nearly all laboratory animals die. At a power density of 100 mW/cm2, for example, a rabbit will die in about 100 minutes and a rat in less than 30 minutes. For these reasons almost all countries regard 100 mW/cm2 as a dangerous radiation level — a level common inside microwave ovens and near the radiating beam of high-power radar or similar antennas. 

At lower levels, cataract formation or other eye damage (e.g., accelerated aging) may result from exposure to radiation of about 80-100 mW/cm2 or more, apparently due to excessive heating. Testicle irradiation resulting in temporary infertility or impotence will occur at about 5-10 mW/cm2. Permanent testicular damage can be expected at similar, but certainly at higher, levels. Such radiation levels are in fact common, as can be seen from Table 4. 

ln the late 1950s, one group or scientists in the United States concluded that below about 10 mW/cm2 no general heating of the adult human body occurs. The present U.S. “safety level” was thus established, based on the belief that heating was the only significant mechanism for biological interaction. Since then, experimental and clinical evidence — first reported in Eastern Europe and now largely duplicated in the U.S. — clearly demonstrates that biological effects occur at lower levels. The scientific community is now embroiled in a debate on a crucial question: Are there nonthermal mechanisms for the interaction of nonionizing radiation with biological systems? Although nonthermal mechanisms are not now understood on a theoretical level, many scientists presume there are “subtle” ways that electromagnetic waves of various frequency may interact with particular biological molecules (such as DNA or proteins) or with particular molecular systems (cell components, cell membranes, etc.) 

While the theoretical debate continues, laboratory evidence mounts, linking biological effects to exposure levels below 10 mW/cm2 (see Table 2). These effects include: altered firing patterns of nerve cells, altered action of particular drugs, altered metabolism and thyroid functions, and a variety of behavioral (primarily motor function) changes. Eastern European reports of low-level (below 1 mW/cm2) effects would expand this list enormously, but some U.S. scientists and administrative personnel dismiss these results, claiming improper experimental or clinical procedures. On the other hand, U.S. scientists have been unable to disprove the Eastern European results, and all but the last of the effects listed in Table 2 are widely accepted by the scientific community in the U.S. Clinical studies in the Soviet Union show behavioral and cardiovascular effects on humans at levels as low as 0.01 mW/cm2. Because no effects are found below this level, 0.01 mW/cm2 is the USSR safety level — one thousand times lower than the present 10 mW/cm2 U.S. safety level. 


A century ago physicists developed a model of the electromagnetic field in which every charged particle is presumed to possess an electric field extending outward in all directions. Accelerating the particle will create a disturbance in the electric field, which then creates a magnetic field disturbance — the two together traveling outward at the speed of light (300,000 km/sec) as an electromagnetic wave (or “radiation”, or just “light”). This is the source of radiation from the sun or a lightbulb, where heat jostles charged particles; or in a radio or television transmission, where electrons are forced to vibrate back and forth in an antenna. 

The fundamental property of these waves is that they transport energy. The continuous range of energies (or of frequencies or wavelengths) is usually represented by the electromagnetic spectrum (see accompanying figure). High frequency (short wavelength) waves — e.g., X-rays and gamma-rays — carry a great deal of energy which enables them to rip apart molecules and knock electrons out of atoms. This is called ionizing radiation. Biologically important molecules (such as DNA) or components of biological cells can be destroyed by these high frequency waves. 

Nonionizing radiation — e.g., radio wave and microwave — is low frequency (long wavelength). It does not carry enough energy to break up molecules or knock electrons out of atoms. Nonionizing radiation does however heat up biological tissue and may also interact with biological systems in ways not yet fully understood. Outdoor and indoor electric power lines as well as infrared and visible light are also in the domain of nonionizing radiation. (These pose their own health hazards but will not be discussed in this article.) The dividing line between ionizing and non-ionizing radiation lies in the ultraviolet. 

The single most important factor in quantifying nonionizing radiation is the amount of energy carried by a wave hitting a surface area per unit of time. This power density (or “intensity) is normally measured in terms of “mW/cm2” (read “milliwatt per centimeter squared”). For example, the power density that cooks food inside a microwave oven is between 500 and 1000 mW/cm2. The power density of electromagnetic radiation a few centimeters from mobile unit radios (Citizen Band, police, ambulance, etc.) is often effectively 10 to 200 mW/cm2. 


The ‘Safety Level’ Controversy 

Biological effects, such as those listed in Table 2, serve as the basis for establishing “safe levels of exposure.” Table 3 summarizes the standard for occupational (8 hour) exposure in various countries. The United States has adopted the least stringent standard ( 10 mW/cm2) in the world, while the USSR has the most stringent (0.01 mW/cm2) — differing by a factor of one thousand. Also listed for comparison are the USSR general population standard (0.005 mW/cm2) and the U.S. microwave oven emission standard (5 mW/cm2). 

The U.S. 10-mW/cm2 standard had its beginnings in the mid-1950s, based on the paucity of information on the tolerance of the human body to thermal increases. As H.P. Schwan — one of the godfathers of the 10-mW/cm2 level — put it, “A figure of 10 mW/cm2 absorbed energy appears as tolerable and is, therefore, suggested as a tolerance dosage. This value should not be exceeded except under unusual circumstance.”1 (Emphasis added.) 

From its inception the U.S. standard was meant to be a tolerance limit, just beyond which adverse biological effects would be expected. Thus in the U.S. if a worker is exposed to an intensity of 1 mW/cm2, this is regarded as acceptable even though such a level may cause discomfort — including headaches, warming sensations, uneasiness or other similar responses (which are exactly the symptoms reported by the Soviets and East Europeans for low levels of radiation). The 10-mW/cm2 standard is peculiar in that it allows for no factor of safety. For ionizing radiation a safety factor of 300 has often been employed. 

By comparison the USSR has based its standard on a no effect criterion: below 0.01 mW/cm2 there are no reported biological effects due to nonionizing radiation. Countries such as Czechoslovakia and Poland have employed a criterion of maximal comfort: while behavioral effects have been observed below 0.1 mW/cm2, it is believed that healthy adults can work comfortably at these levels. It must be emphasized, therefore, that the U.S. standards is a result of the relatively lax attitude toward health and safety. 

The U.S. “acceptable level of exposure” to nonionizing radiation is a tolerance level which includes no factor of safety. There is at present no standard for exposure to the general population in the U.S., and the standard that applies to workers is a voluntary standard — without the force of law. 



Maximum Permitted Radiation Intensity*(mW/cm2 ) Country 


0.005 USSR (general population)**
0.01 USSR
0.025 Czechoslovakia
0.2 Poland
1.0 Sweden

from MW oven

U.S.-BRHa: 5cm

(1 proposed) 

10.0 Great Britain
10.0 U.S.-ANSIb 



a Bureau of Radiological Health  

b American National Standards Institute 

c Occupational Safety and Health Administration 

d American Congress of Governmental Industrial Hygienists  

*Apply to limited frequency ranges, typically between 300 MHz and 300,000 MHz. 

**Several countries have more stringent standards for the general population than the occupational (8 hr) standards listed here; the U.S. has no standard for the general population. 


Today, with a growing wealth of experimental work and increasing public awareness, dissatisfaction with the U.S. standard is mounting and reaches throughout the scientific and administrative spheres. Moris Shore, director of the Division of Biological Effects at the Bureau of Radiological Health, commented in 1977, 

There are mistakes that have been made in the past, and I would hope that these could be avoided. A specific example is the certification of safety of 10 mW/cm2 for indefinite human exposure in the absence of any studies in animals or in man that tested the chronic or lifetime effects of exposure to 10 mW/cm2. Such certification, based on ignorance, strains the credibility of a level that is recommended as being adequate to protect health and safety, particularly of the general population.2

Overexposure Abounds 

There is good reason to believe that the U.S. standard is far too high — by a factor of ten to a hundred, perhaps as much as a thousand. What are the actual environmental and workplace exposures in the U.S.? 

Table 4 summarizes some of the many possible exposures to nonionizing radiation. Note that even in terms of U.S. standards, more than half of the listings on this table record work and living environments in which people are continually (and often unknowingly) overexposed! Overexposed populations include military personnel, industrial radio frequency workers, patients, nurses and doctors in close proximity to radiating units, Citizen Band radio operators, some users of microwave ovens, some populations very close to FM radio antennas, and personnel near the Satellite Power System, should it be developed. 

Industrial radio frequency equipment is particularly dangerous. In one study of 82 radiofrequency sealers in 12 plants, over two-thirds of the operators (all women, some pregnant) were overexposed. The investigators of that study noted that health and safety personnel at the relevant plants were not even aware that a hazardous condition could exist. About 20% of the U.S. industrial work force is estimated to be exposed to such radiation. 

A limited study of electrosurgical (“Bovie”) units — used in every operating room in the U.S. to cut and sterilize flesh — found field levels near or above the U.S. acceptable standard. Similar studies have revealed that Citizen Band (CB) radios — of which there are about 30 million in the U.S. — also pose immediate health hazards to users and bystanders. Levels for hand held units were measured or estimated to be anywhere from 10 to 100 mW/cm2 (or more) at eye level. (Over time, levels above 80 mW/cm2 are known to cause cataracts.) Mobile unit radios pose similar, if not more severe, health hazards

There are about 10 million microwave ovens in use: in the home, at work, in restaurants and hospitals. In 1973 the Consumer’s Union labeled all microwave ovens “Not Recommended” because of excess radiation — in some cases above 20 mW/cm2. Microwave ovens must be recalled by the manufacturer if they exceed emissions of 5 mW/cm2. Recent safety improvements have resulted in withdrawal of Consumer’s Union “Not Recommended” label on models built after 1976. Typical emissions in recent years run about 0.1 – 1.0 mW/cm2, yet some ovens still radiate above 5 mW/cm2. The Bureau of Radiological Health (FDA) has found that fewer than 1 percent of the post-1975 ovens emit at these higher levels. However, with a total of 10 million ovens in use, this could mean that as many as 100,000 microwave ovens presently in use emit radiation above the 5-mW/cm2 standard. In fact, in March of 1979, 2600 Roper and Sears brand microwave ovens were recalled by the Food and Drug Administration because of excess leakage. 

The most widespread exposure of the general population results from AM, FM and TV transmissions (see Table 4 for examples). Although these exposures are in general below the level of any known biological effect, particular populations — primarily those near transmitting antennas — may be dangerously overexposed. 

There has been a good deal of attention paid by the media to microwave radiation trained on the American embassy in Moscow. What has been emphasized is the possibility of associated health hazards. It is interesting to note (see Table 4) that the maximum reported levels of this radiation are well within the U.S. limit of 10 mW/cm2 — less than that encountered continuously in some U.S. office buildings! 

SPS: An Issue for the 1980s? 

A new technology very possibly on the way is the Satellite Power System (SPS), often referred to as the Solar Power Satellite. It will consist of earth orbiting satellites, each utilizing a wall of solar cells to convert solar energy into electrical energy. The energy will be transmitted down to earth via microwave beams. The gigantic receiving antenna on earth, 17 km by 13 km, will have a microwave power density of 20 mW/cm2 at least 2 km from its center. In addition, there will need to be a 2 km buffer zone around the perimeter of the huge antenna in order to reduce radiation levels to 0.1 mW/cm2. 

Each antenna will require 55,000 acres. With a plan to develop 60 SPS sites (to produce a hopeful 20% of the U.S. energy desires by the year 2000) a total of 3.3 million acres of land will be required — all restricted because of dangerously high microwave power densities. Workers at the sites will have to be continually shielded from the radiation, and any living organism venturing within the area will be endangered. Bird migration patterns, for example, could be significantly affected. In November 1979 the House of Representatives gave the go ahead for preparatory development — the projected cost of the entire project ranging from $500 billion to $1 trillion. 

Political and Economic Issues 

Ostensibly, a nonionizing radiation safety level is a scientific issue involving two determinations: What experimental data should be accepted as the most relevant? And, if effects are discerned, when does an effect constitute significant harm? But these are not objective scientific questions. 

The very fact that a wide range of standards exists throughout industrialized countries points to this conclusion. Between countries and within countries there is a discrepancy as to what constitutes “proper” scientific procedure or as to what constitutes significant information. Thus Eastern European and Soviet researchers report biological effects at very low levels of radiation, based on experimental and clinical studies which many U.S. scientists reject through claims of improper scientific procedure. In the Soviet Union, for example, a condition of “microwave sickness” is diagnosed among workers from their subjective complaints of headaches, nausea, uneasiness, etc., when exposed to very low levels (0.1 mW/cm2) of radiation. Such a diagnosis in the Soviet Union is a basis for having additional protective shielding installed or for being transferred out of the work environment. But in the United States such complaints are not considered sufficient to assess a deleterious health condition. 

The dividing line between effect and harm is also a subjective one. A microwave intensity above 10 mW/cm2 certainly heats the body, but then so will a hot bath. Scientists who believe heating is the only effect of low level radiation will claim experimental work that concludes otherwise is probably faulty and did not take proper account of this or that factor. Other scientists believe there may be other mechanisms (nonthermal) which we do not presently understand but which may very well exist. This group accepts the experiments showing effects at low levels and therefore concludes that harmful effects are likely. 

The issue is also an economic one. It may very well cost millions, if not billions, of dollars to clean up electromagnetic pollution. As indicated in Table 4, industrial radio frequency devices have been found to expose workers to levels far above 10 mW/cm2. With some 35 million such devices in operation, the economic cost of correcting this problem alone is staggering. 

The military, by far the largest single user of nonionizing radiation, has argued that compliance with standards demanding lower exposure levels would threaten national security. Typical ship radar emits at levels of 10 mW/cm2 out to about 25 feet (much farther for high-power radar). If the “safety level” were placed at 0.1 mW/cm2, the safety distance would extend to over 200 feet and would seriously interfere with onboard personnel movements. At one of the earliest conferences on the subject, a Naval scientist declared, “Restrictions have been imposed upon the Army, Navy and Airforce because of radio frequency hazards. This is a serious situation. Every restriction results in a reduced capability of our fighting forces, and therefore fleet commanders oppose the restrictions. They emphasize we cannot afford the restriction.”3

Paul Brodeur, writer for The New Yorker and author of The Zapping of America, has concluded that the issue of nonionizing radiation is nothing less than a “microwave cover-up”:  

[T]he federal government, the military, the vast electronics industry, and all of the academic and research institutions financed by the military-electronics industry complex have been standing on their collective head to avoid conducting meaningful epidemiological studies on the health hazards posed by microwave radiation. People in the military-electronics industry complex don’t want to know the extent of the problem. If they knew about it they might have to admit they knew about it, and then might even have to do something about it, which would cost a lot of money both in terms of litigation and preventive measures.4  

Out of the Crisis 

Nonionizing radiation is an example of a presumed benevolent technology which, because found useful for military and corporate purposes and for social benefit, has become intertwined in our lives to a potentially dangerous level. When it first gained widespread use some 30 to 50 years ago, little work was done to explore its biological and environmental consequences. While the responsibility for that failure in technology assessment is deeply rooted — and perhaps muddled — in the American tradition, the continuing irresponsibility of the last 20 years is clear. The military and corporations have vested economic and operational interests. Certainly the consumer is not to blame. Those responsible for this reckless proliferation — the military and corporations — should therefore be the ones to pay for independent research into adverse effects, improved safety shielding and redesign, and substitution of safer technologies for dangerous ones. 

Given this history, decision making power must rest with the general public and with the affected workers. “Safety level” issues and even the “need” for a particular technology must be subject to this kind of review. For this the public needs clear and precise information on the current and proposed uses, the effects, and the levels of nonionizing radiation exposure. Unions and workers must understand the technology, be aware of its effects, and know where and at what levels they occur. 

It is an illusion that any technology is passive — that technology can be scientifically objective, that technology is socially and politically neutral. Every technology is in a dynamic relation with its social and economic conditions — each embodying, revealing, redirecting the other. People are a part of that process. Recognizing first that the illusion of a passive technology obscures the dynamic relationship, we must then actively engage in that relationship in order to change it. Failure to do so in the case of nonionizing radiation has led to our present crisis.

>> Back to Vol. 12, No. 2 <<


  1. H.P. Schwan and K. Li, “Hazards Due to Total Body Irradiation by Radar” in Institute of Radio Engineers. Proceedings 44 (1956), p. 1581.
  2.  Moris L. Shore in Symposium on Biological Effects and Measurement of Radio Frequency/ Microwaves. DeWitt G. Hazzard, ed., HEW (FDA) 77-8026 (1977), pp. 9-10.
  3. James N. Payne in Biological Effects of Microwave Radiation, Vol. I, Mary F. Peyton, ed. (New York: Plenum Press, 1961), p. 323.
  4. Paul Brodeur, The Zapping of America: Microwaves, Their Deadly. Risk, and the Cover-Up (New York: Norton’ Company, Inc., 1977), p. 188.