The following text is a proposed techinical paper for the upcoming
Canadian Amateur Radio Convention. The talk will be given to individuals
with extremely varied techinical background and minimal medical or
scientific background. Comments appreciated!
HAM RADIO: HAZARDOUS TO YOUR HEALTH? RAC CONVENTION 1994
Dr Rick Zabrodski M.D.
Over the past 10 years the general public has become increasingly concerned about
electromagnetic fields (EMF) and their possible effects on the human body. There have
been numerous articles in the press linking electric power lines and other electrical
equipment such as cellular phones to cancer in particular.
After reviewing the currently available data my conclusion is that if there is a serious
health hazard for the ham radio hobbyist, it is a relatively small one. At present it appears
that EMF and its effect on the typical ham radio operator is not likely to be a major
problem. This is apparent when comparing EMF to the many well known, documented
hazards that we subject ourselves to on a daily basis. This does not mean however, that
there are no concerns with EMF exposure and further study together with "prudent
avoidance" is advised. I will present a brief summary of what is currently known on this
incredibly complex and rapidly expanding area of research. A rationale for appropriate,
prudent behavior based on this knowledge will then be presented.
To better understand the issues involved in EMF, we must first define what particular
areas are relevant to the hobby of Ham Radio. EMF is usually divided broadly into two
categories, Ionizing and Non Ionizing. Ionizing radiation includes frequencies from the
ultraviolet spectrum and up. Examples include solar radiation, x-rays and nuclear
explosions. The serious side effects of ionizing radiation are well known and depend on
frequency, intensity and duration of exposure. Based on this knowledge, there are
currently specific public and occupational exposure standards (e.g. x-ray technicians,
nuclear plant employees). Fortunately, your transmitter does not emit any ionizing
radiation!
The second area of EMF more relevant to amateur radio are those frequencies in the "non-
ionizing" spectrum. This spectrum stretches from very low frequencies to the infra-red
region. Examples include power lines, transformers, electric motors and radio frequencies
stretching from VLF through microwaves. Non-ionizing EMF is further subdivided as
thermal or athermal. This refers to the measurement of actual tissue heating. The issue
here is that of wave length and intensity. For example, we know that we can use relatively
low power microwaves to cook food and low power infrared lasers to burn tissue.
However if an individual was situated near a high power (megawatt) mf/hf/vhf antenna
biological heating (thermal effects) would also be evident. The ANSI guidelines have
suggested limits for public and occupational exposure in this area. It should be noted that
these limits have been repeatedly lowered over the years. They remain a source for
continued debate.
For our purposes, the main consideration in amateur radio is usually that of lower level
radio frequencies that do not cause measurable heating to the body and are therefore
classified as athermal. It should be pointed out that currently there are no published
scientific safety standards for power levels and frequencies that do not cause thermal
effects. This is where most of the controversy begins! There is still not enough scientific
evidence to define clearly what is going on here. Despite this we hear emotional
statements from concerned citizens' groups and the equally polarized public relations
statements of profit oriented multinational corporations. The implication for various self
interest groups including amateur radio is tremendous. If a case for a cause and effect
health hazard can be made, the cost implications will be enormous. If you think antenna
restrictions are a problem, consider the implications of having to prove that you have a
EMF compliant radio station!
A wide variety of scientific investigations from numerous sources now show that there
clearly are measurable biological effects secondary to athermal EMF. In examining these
effects, the following hierarchy of biological functioning has been examined:
Free radicals
Cellular
Tissue
Organ system
Whole organism
Populations
To complicate things even more, research done at the cellular and tissue level suggests
that other factors besides frequency and intensity are important. The EMF modulation,
bandwidth and pulsatile vrs steady state characteristics have all been shown to have
different effects. It is apparent that certain EMF "windows" may be more important than
others.
What are some of these effects? At the cellular level we know that EMF causes
measurable changes with calcium and hydrogen ions. There appears to be changes in
cellular communications by way of electrochemical and enzyme pathways. These effects
have been studied particularly in immune cell function (T-cells) as well as cell growth and
other types of cell recognition systems. At a tissue and organ level, we now have evidence
that the brain hormone melatonin, is also effected. All the above are certainly interesting
to the Ph.D. biologist, but how do they affect you and me?
The current literature suggests that EMF likely does not cause cancer. However, it may
have a role as a promoter (enhancer) of cancer by modifying the cells in the immune
system that normally act to prevent or correct cancer in its early stages. In other words,
cancer cells may be created by a chemical agent or ionizing radiation. Subsequently the
EMF handicapped immune system may not be as effective in identifying and destroying
these cells in time to prevent further cancer cell growth.
At the other end of the cellular spectrum are the "groups of organisms" that we call a
population. The study of populations and relationships with disease is called
Epidemiology. The often quoted study of 67,829 male, mainly Californian Hams in the
1980's suggested a small increase in several types of cancers.
Several points should be noted about this study. First, there was a reported decreased
incidence in certain other cancers. Furthermore, these Hams did not die any sooner than
would be anticipated for anyone else. It was also pointed out that one third of these amateur radio operators had occupational electromagnetic exposure together with possible
exposure to other potential hazards including solder fumes and toxic chemicals. This study and many others like it did not involve any actual measurement of
cumulative EMF exposure, only that such exposures were likely to occur. What about the
effects of EMF on female hams who live in Iowa? Often epidemiological studies give
rise to more questions rather than answers! Some subsequent epiemilogical studies
involving occupational exposures (generally much higher than hobby exposures) to EMF
tend to support the atypical cancer findings initially described. These individuals were
usually exposed to numerous other agents and it appears that chemical exposure was
particularly important. What we can say about the "silent key" study is that there is an
apparent relationship of still uncertain significance but certainly there is no proof of a
cause and effect relationship with cancer.
Therefore, we now know that non ionizing, athermal, low level radiowaves used in
amateur radio do cause biological changes in the human body that are measurable at the
cellular, tissue, and organ system level. The significance, if any, of these changes remains
uncertain. It currently appears unlikely that these changes can be directly linked to
causing cancer. Unfortunately there does remain the possibility that they have a small but
not yet clearly defined role in allowing other more toxic agents to cause cancer by
promoting or enhancing their effects. Other effects may exist, both good and bad, that are
yet to be described. I believe that it will ultimately be in this area of biological rather than
epidemiological research where we find the definitive answer to our questions. At the
same time we may also develop a better understanding of cancer and immunological
diseases such as arthritis and AIDS.
When we look at the scientific evidence at the organism and population level, the possible
link between cause and effect concerning EMF and disease continues to be poorly
understood. Nonetheless, there remains evidence for concern, particularly in those
individuals with significant exposure to EMF and other potential cancer causing agents in
their occupations. More study in this area is also indicated!
Considering the above information, it may be considered wise to practice what has been
called "prudent avoidance." As a ham radio-physician, here is my advice:
Don't smoke
Don't get fat
Eat sensibly
Exercise regularly
Wear a seatbelt
Wear a bicycle helmet
Climb your tower on sunny, windless days and use a proper belt
Paying attention to the above issues will provide a clear, measurable and significant benefit
to your long term health. With the above duly noted, what about ham radio and EMF?
First, we must recognize that the ANSI guidelines are based on THERMAL guidelines.
Furthermore, they do not take into account the modulation dependent interactions that
seem to be important in athermal EMF research. In fact, there are no guidelines for ham
radio type exposure to EMF at the present time. However, I certainly would agree with
the following:
QRP : Use the lowest possible power as conditions permit.
This is particularly important with the higher frequencies and in situations where the
antenna is close to the operator. The use of UHF/VHF handhelds would ideally involve a
separate microphone with the radio and antenna held above your head. If this is not
possible, the handheld should be kept as vertical as possible using low power and brief
transmissions. (Leave the long winded lectures to 75 metre AM.)
When operating HF at levels of 100 watts or less, beams should be kept at least 35 feet
above the ground and higher when using more power. On a typical suburban lot a vertical
should be roof mounted. (They usually work better up there in the clear anyway). Any
indoor antennas should be restricted for QRP use only.
Finally, your linear should be reserved for "true emergencies" such as working 3Y0PI on
the last day of the Dxpedetion as a "new one" for the DX honor role. I would emphasize
that special care is required when operating at microwave levels as the chance of
significant athermal and thermal exposure is much higher. Further, more detailed
suggestions can be found in various sources including the ARRL Handbook and the
ARRL Antenna Book.
In summary, we now know that non-ionizing, low level, athermal EMF does cause
measurable biological effects. The consequences of these findings are yet to be accurately
assessed but further information will be forthcoming. Those at highest potential risk are
individuals with prolonged occupational exposure to EMF and have additional exposure to
other potentially toxic agents. Although further study is needed, it appears that the risk
involved with ham radio EMF exposure remains low when compared to other established
health risks. "Prudent avoidance" is recommended.
I hope this encourages all of you to quit smoking, eat smart and exercise safely. These
measures together with prudent QRP operation and high antennas will hopefully allow us
all to discuss this topic again for many years to come!
