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file: \public\info\tis\bio.txt updated: 01-09-95

Reprinted from: April 1994 QST "Electromagnetic Fields and Your Health"
Copyright 1994 American Radio Relay League, Inc. 
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Electromagnetic Fields and Your Health

Are the electromagnetic fields generated by power lines, TVs 
ham radio gear and hundreds of other devices bathing us 
in damaging radiation? The jury is still out, but you can 
take steps to protect yourself from danger--real and 
potential. 

By Wayne Overbeck, N6NB
   14021 Howland
   Tustin, CA 92680

     There is a growing public debate about the safety of 
electric power lines and the electrical equipment that we 
use every day in our homes and workplaces. Not long ago, a 
lawsuit was filed alleging that a Florida woman's brain 
cancer was caused by electromagnetic radiation from a hand-
held cellular telephone. Although the filing of a lawsuit 
proves nothing (thousands are filed every week, and this one 
was promptly dismissed by a court), the lawsuit made 
national headlines for weeks and caused cellular telephone 
industry stock prices to decline on Wall Street. 

     The news media regularly cover many facets of the 
controversy over the possible health effects of 
electromagnetic fields (EMFs). In addition to stories about 
lawsuits, there have been numerous media accounts of medical 
research concerning EMFs--some of them confusing and 
seemingly contradictory. And there have been news stories 
about activist groups fighting the construction of new power 
lines or cellular telephone towers in their neighborhoods. 

     This intense publicity has alarmed many people, 
prompting them to worry about the safety of their homes, 
neighborhoods, schools and workplaces. There is a growing 
concern that the electromagnetic fields produced by power 
lines and everyday household appliances may be hazardous. 
As the tension mounts, more and more hams are faced with 
this difficult question: Is your Amateur Radio station 
hazardous to our health? 

     Fortunately, enough research has now been done that we 
know most Amateur Radio activities are quite safe. In fact, 
scientists from the Federal Communications Commission and 
the Environmental Protection Agency conducted a field survey 
of EMFs at typical Amateur Radio stations in 1990. They 
concluded that most amateur operations do not produce EMFs 
strong enough to pose any health hazard. And for many years, 
the American Radio Relay League's Board of Directors has 
also been monitoring the ongoing research about EMFs and 
health through a board-appointed Committee on the Biological 
Effects of RF Energy. There is extensive coverage of the 
issue of EMFs and health in both The ARRL Handbook and The 
ARRL Antenna Book--with recommendations for safe Amateur 
Radio operating practices. 

     Amateur Radio is a hobby that can be pursued safely, 
provided everyone observes a few simple precautions. This 
article was written to summarize what we know about EMFs and 
health, and to suggest safe operating practices. 

Scientific Background

     When scientists talk about electromagnetic fields, 
they're talking about several very different forms of 
energy. Low frequency or "power-line frequency" fields are 
produced by electric power lines and appliances, typically 
operating at a frequency of 60 Hz. Much research is now 
underway concerning the health effects of 60-Hz fields--the 
kind of EMFs found in virtually every home and workplace. 
Additional research is being done to investigate the 
possible health effects of radio frequency (RF) energy, 
which is much higher in frequency than the electric energy 
in power lines. RF energy is produced by radio and 
television transmitters, radar installations, cellular and 
cordless telephones, microwave ovens and even remote 
controls for garage door openers. 

     Low-frequency and RF energy are forms of nonionizing 
radiation: The frequency is too low to produce enough photon 
energy to ionize atoms. In contrast, ionizing radiation--
which is not produced by power lines or radio transmitters--
can cause severe and well-documented health hazards. Nuclear 
weapons produce enormous amounts of ionizing radiation, 
while small, carefully controlled doses of ionizing 
radiation are used in medical X-ray equipment, for example. 

     The present controversy concerns nonionizing radiation, 
including power-line frequency and RF energy. Much is now 
known about the biological effects of this kind of energy, 
but there is much more that we do not yet know. Before World 
War II, scientists knew that non-ionizing radiation could 
produce thermal (heating) effects. At sufficiently high 
power levels, EMFs can cause body heating, which may result 
in health hazards such as blindness or sterility. Most 
ordinary household appliances and transmitted radio signals 
produce EMFs far weaker than those required to produce 
thermal effects. On the other hand, microwave ovens do 
generate EMFs strong enough to produce thermal effects: 
That's precisely why they can heat and cook food. The trick 
is to keep the EMFs safely inside the oven--away from 
people. For obvious reasons, microwave ovens must meet 
strict safety standards. 

     In recent years, a new element in the debate over EMFs 
and health has been the finding that even at athermal 
levels--energy levels too low to cause body heating--
electromagnetic energy appears to have various effects on 
the human body. The first scientists whose work in this area 
gained widespread media publicity were epidemiologists--
medical researchers who look at the health patterns of large 
groups of people, using statistical methods. 

     Over the last two decades, a number of epidemiological 
studies have found that electrical workers have higher-than-
normal death rates from certain cancers, including leukemia, 
lymphatic cancer and brain cancer. Other epidemiological 
studies have shown that children living near some types of 
power lines have higher-than-normal rates of leukemia. Still 
other studies have concluded that persons exposed to certain 
chemical agents such as solder fumes in addition to high 
EMFs have up to 10 times the normal rate of certain cancers. 

     All of these studies involved groups of people who were 
not ordinarily exposed to EMFs strong enough to cause body 
heating. Thus, their health patterns suggested that low-
level EMFs may pose health hazards. 

     There have been other epidemiological studies, however, 
that did not confirm some of these findings. And still other 
researchers have concluded that environmental factors such 
as the alignment of the earth's natural magnetic field may 
interact with man-made EMFs to alter these health effects. 
(The earth's magnetic field is stronger than many man-made 
fields, but it is a static, direct-current field. Most man-
made EMFs are alternating-current fields operating at a 
variety of frequencies and power levels.) 

     There are other dimensions to this problem, too. Some 
of the research that failed to confirm a correlation between 
EMF exposure and health was funded by industry groups that 
have a financial stake in the outcome of the research. 
Critics have challenged the credibility of some of the 
research for that reason. Moreover, epidemiological research 
only reveals health patterns; it does not prove what caused 
those health patterns. If electrical workers have an 
abnormally high rate of certain cancers, that may result 
from their occupation--or it could result from something 
else. In short, the work of epidemiologists shows 
correlations without proving causation. That raises 
troubling questions without providing definitive answers. 

     Responding to the questions raised by epidemiologists, 
a number of medical researchers have launched laboratory 
based studies of the effects of EMFs on living tissue. There 
has been an explosion of knowledge about molecular biology 
and the related field of genetics in recent years, and one 
of the focal points of this research has been the role of 
electromagnetic signals at the molecular level. Among other 
things, there have been studies suggesting that certain 
types of electromagnetic fields may alter the body's genetic 
makeup, causing chromosome damage. 

     It is also known now that some EMFs may disrupt the 
flow of vital chemical and electrical signals between cells 
in the human body. EMFs appear to alter the passage of 
chemical and electrical signals through the cell membrane 
(the thin layer of material that covers each cell). This has 
caused some scientists to conclude that EMFs may sometimes 
affect the work of the body's immune system in fighting 
cancer. 

     If the body's cancer-fighting T-cells fail to detect 
that a particular cell has become cancerous because cell-to-
cell communication is disrupted by EMFs, that would increase 
the risk of a tumor developing. There is also laboratory 
research indicating that EMFs may inhibit the body's cancer-
fighting ability in other ways. 

     Researchers have found that certain EMFs reduce the 
activity of messenger enzymes called protein kinases and 
also affect the way cell growth is regulated. There is also 
evidence, now confirmed through research in several 
countries, that EMFs sometimes work together with cancer-
promoting chemicals to increase the risk of cancer beyond 
that associated with either the chemicals or EMFs alone. 

     EMFs also appear to change the body's rate of 
production of certain hormones that have cancer-inhibiting 
effects, such as melatonin. Some studies have found that 
persons sleeping under electric blankets have lower-than-
normal levels of melatonin production when the blanket is 
operating, but their melatonin production returns to normal 
when the blanket is switched off. Some scientists think the 
effect of EMFs on melatonin production may explain many of 
the apparent health effects of exposure to low-level fields. 

     As with the epidemiological studies, laboratory 
research has raised questions and stirred controversy. Some 
laboratory studies have been difficult to replicate: Other 
researchers have not always observed the same results when 
they attempted to repeat some experiments. There appear to 
be other variables that affect the outcome of research on 
the biological effects of EMFs. 

     For example, there is evidence that low-level EMFs have 
significant biological effects only at certain frequencies 
and intensities--and not at other frequencies or 
intensities. There is a general rule about toxic and cancer-
causing chemicals: If some is bad, more is worse. That rule 
may not necessarily apply to EMFs, however: Some studies 
have detected biological effects of low-level EMFs--but not 
when the field is stronger. 

     There are also studies showing health effects at certain 
frequencies but not at adjacent frequencies. And there are 
studies suggesting that a radio signal modulated by certain 
low frequencies, or a signal that is keyed or pulsed, has 
more harmful effects than an unmodulated, steady carrier. 
Scientists call these kinds of phenomena window effects, and 
they greatly complicate any attempt to understand the 
relationship between EMFs and health. 

     There is an unfortunate footnote to this research on 
window effects: Much research seems to indicate that there 
is a window at 50 or 60 Hz--the exact frequency of the 
electric energy traveling through millions of miles of in-
home wiring in the US and many other countries: EMFs at 
higher and lower frequencies may not have the same health 
effects as 60-Hz fields. And yet, the financial and 
technical obstacles that would stand in the way of changing 
the frequency of ordinary household ac current--should that 
prove to be desirable--are staggering. 


Safe Operating Practices

     After reading this far, if you are uncertain about the 
possible health effects of EMFs, you're not alone: The 
scientific community itself does not agree about this issue. 
In fact, medical doctors, biologists, physicists and other 
scientific researchers are engaged in an intense, sometimes-
emotional debate about the health effects of EMFs. There is 
a computer bulletin board system for scientists concerned 
about this issue; messages posted there range from esoteric 
discussions of these complex issues to personal attacks on 
some scientists who espouse views not shared by others! 

     If the experts don't always agree, how can the rest of 
us know what is safe and what isn't? The American National 
Standards Institute (ANSI), a private body that sets 
voluntary standards for industry, has had guidelines for 
exposure to EMFs for many years. In fact, the ANSI 
guidelines have been revised downward repeatedly to reduce 
the recommended safe levels of EMF exposure. 

     ANSI adopted its latest guidelines in 1992, but many 
health scientists have questioned whether even the newest 
guidelines are adequate to protect public health. Recently, 
the Environmental Protection Agency publicly questioned the 
adequacy of the 1992 ANSI standards in an official statement 
to the Federal Communications Commission. 

     Some scientists challenge the newest ANSI standard on 
several grounds. For one thing, it's primarily intended to 
prevent exposure to EMFs strong enough to cause thermal 
effects, not exposure to weaker EMFs that may cause athermal 
effects. Nor does the ANSI standard take into account the 
effects of modulation. And the ANSI standard applies only to 
RF energy, not to low-frequency EMFs that are so central to 
public debate these days. 

     There is no generally accepted standard in America for 
exposure to the low-frequency fields produced by power lines 
or home appliances. And in general, there is considerable 
uncertainty about what level of electromagnetic energy 
should be considered safe. 

     Another problem is that RF fields are difficult to 
measure. The price of a professional quality RF power 
density meter runs well into four figures, and low-cost 
meters for home use are often grossly inaccurate. Even the 
best meters may not be accurate in the near field, the area 
close to an antenna where the potential for hazardous RF
energy levels is greatest. 

     Field strengths can be calculated using mathematical 
formulas, but that, too, fails to take into account the 
random hot spots that often exist in the near field. 
Fortunately, the low-frequency fields from power lines and 
appliances are easier to measure than RF power densities. 

     If there is no consensus about safe energy levels, and 
if EMFs are difficult to measure, what can we do to 
minimize the potential health hazards of EMFs? 

     Several years ago, Professor M. Granger Morgan of 
Carnegie Mellon University offered a simple proposal: 
practice prudent avoidance. Dr Morgan said we should avoid 
unnecessary exposure to EMFs as a common-sense response to 
potential--but not yet proven--health hazards. He didn't 
suggest that we all abandon our electric appliances and go 
off to live in the woods in cabins without electricity, but 
he did suggest that we minimize exposure to EMFs when it's 
practical to do so. 

     He said, in essence, to avoid electromagnetic fields 
strong enough that they may have adverse health effects. The 
League has adopted Dr Morgan's approach: The RF safety 
sections of major ARRL publications urge radio amateurs to 
practice prudent avoidance wherever possible. 

     Which amateur operating practices are clearly safe, and 
which ones might be hazardous? Here are some suggestions 
based on guidelines developed by the League's Bio-Effects 
Committee: 

     * Transmitting antennas should be mounted well away 
from living areas. If medium or high transmitter power (100 
watts or more) is to be used, antennas should be mounted on 
a mast or tower at least 35 feet above any populated area if 
possible. The FCC/EPA study indicated that with an antenna 
that high, there is little RF energy where people are. 

     Because feed lines can radiate in some cases, when 
installing open-wire line (or even coaxial cable if the SWR 
on the line is high), it's best to route it away from areas 
where people will be spending a lot of time.

     * When using a ground-mounted or mobile antenna, be 
careful not to transmit when anyone is near the antenna. A 
good rule of thumb is to avoid transmitting when anyone is 
within three feet of a car-mounted 2-meter FM whip if you're 
using a typical 25-watt transceiver. With a 100-watt 
amplifier, don't transmit when anyone is within five or six 
feet of a whip antenna. If you're using a beam antenna and 
100 watts or more, follow the 35-foot rule: Don't transmit 
when anyone is within 35 feet of the front of the antenna 
(the direction where the antenna is pointed). It may be safe 
to transmit when people are a little closer to the antenna 
if everyone is below it or behind it, not in front of it. 

     * Exercise particular care when using indoor antennas, 
including those mounted in attics, because in some 
situations they can generate substantial RF fields. As much 
as possible, try to locate indoor antennas as far from 
people as possible. Use low power (10 watts output or less), 
and keep your transmissions short when someone might be near 
the antenna. 

     * Never use a power amplifier that has its metal cover 
removed. The cover provides shielding, keeping the RF energy 
inside the unit--not out in the room. 

     * If you're going to experiment with UHF or microwave 
equipment, or do moonbounce communications, discuss your 
installation with experienced operators before getting on 
the air. UHF and microwave antennas and waveguides--as well 
as high-gain moonbounce antennas--may produce hazardous 
levels of RF energy and must be installed carefully so that 
no person is in the line of fire. Never look into an 
activated waveguide or stand in front of a high-gain VHF-UHF 
antenna when the transmitter is on. 

     * When using a hand-held transceiver, use the lowest 
power possible and keep the antenna as far from your head as 
possible. Within the scientific community, there is 
disagreement about the safety of "handy talkies." Most hand-
helds have been exempt from the ANSI standard because their 
power output is too low to produce significant whole-body 
heating. However, there is growing evidence that even one- 
or two-watt hand-held radios may produce significant EMFs 
within the user's head, with possible health effects that 
are not yet fully understood. (The potential for a health 
hazard is greatly reduced when a hand-held radio is used in 
its low-power position, with only a fraction of a watt of 
output power.) 

     * Be aware that low-frequency fields exist in your 
home. If possible, avoid being within 24 inches of any 
electric motor or power transformer while it is turned on. 
Hair dryers, ac-operated hand drills and other electric 
devices that are held close to the body when in use often 
expose users to stronger EMFs than those produced by Amateur 
Radio equipment. Nevertheless, it is a good idea to stay 
about 24 inches away from the fans and power transformers 
found in high-power amplifiers and 12-volt power supplies, 
for example. 


Further Information

     The issue of electromagnetic fields and health is as 
complex as it is controversial. It isn't possible to cover 
this topic fully in a short article such as this one. A more 
detailed and technically-oriented treatment of the subject 
appears in the "RF safety" sections of current editions of 
The ARRL Handbook and The ARRL Antenna Book. The 
bibliography there lists some of the major scientific works 
in this field. 

Wayne Overbeck, N6NB, holds PhD and JD degrees and is a 
Professor of Communications at California State University, 
Fullerton. He is a member of the ARRL Bio-Effects Committee, 
and first became interested in this subject because his own 
operating activities--VHF DXing and contesting with high 
power portable stations on mountaintops--require special 
precautions to minimize EMF exposure.


Captions for Overbeck's Bioeffects article:

[Photos A and B go together]

PHOTOS A and B: This 3-element 6-meter beam is only a few feet above 
N6NB's second-story hamshack. When the antenna is pointed toward 
the operating position, fields in excess of ANSI standards were 
measured were measured in the shack on a laboratory-grade hazard 
monitor. The transmitter power output was set to 900 watts.


PHOTO C: Dr Robert Cleveland (FCC) and Ed Mantiply (EPA) measure 
RF fields generated by a hidden wire antenna at a condominium 
complex. When local restrictions force hams to use indoor or 
hidden antennas, extra safety measures should be taken.


[photos D and E go together]

PHOTOS D and E: Many home appliances produce strong low-frequency 
electromagnetic fields. The 60-Hz field generated by this hand 
drill, for example, is in excess of 1200 milliGauss. In contrast, 
the field 12 inches in front of the 1-kW Amateur Radio amplifier 
is about 10 mG. The main sources of 60-Hz fields in ham gear are 
power transformers and cooling fans.

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The members and HQ staff would like to thank the following people 
for their contributions to this information file:

N6NB

Send any additional information or changes to mtracy@arrl.org. 

73 from ARRL HQ.

