BRAIN CANCER, LEUKEMIA FROM HAM RADIO
Marc DePaul
If this has been discussed before, I'm sorry, I haven't seen it.
The ARRL handbook mentions that we should keep the face of an amp
at least 24 " from our body, etc. Rigs, power supplies, antenna tuners,
and antennas are also hazardous to our health when set too close to our
body.
So now my amp is approx 4 feet from me, and my open wire antenna tuner
is now 7 feet from me. I'm also about 2 feet from the face of the rig.
I'm hoping that will do the trick to be immune from cancer...
They mention that attic antennas are a no-no, and it appears mobiling
douses your body with an rf field big time.
There is statistically significant cancer rates above the non-electronic
population.
What I want to hear out there is anyone who has done, or is knowledgeable
of work done in this field...Let us know.
Regards,
Marc
Brent Irvine
>
>The ARRL handbook mentions that we should keep the face of an amp
>at least 24 " from our body, etc. Rigs, power supplies, antenna tuners,
>and antennas are also hazardous to our health when set too close to our
>body.
It might be hazardous because of RF burns: if you stand too close
to an emitting radar dish or high power antenna array you will get
burns on your body. Lower power WILL heat your tissues a bit, though
any claims of cancer are unsubstantiated and are probably bogus.
>So now my amp is approx 4 feet from me, and my open wire antenna tuner
>is now 7 feet from me. I'm also about 2 feet from the face of the rig.
>I'm hoping that will do the trick to be immune from cancer...
Well your tissues will probably be unheated (below the background
level anyway...
>They mention that attic antennas are a no-no, and it appears mobiling
>douses your body with an rf field big time.
It would depend on how your house is shielded. If you were to put a
layr of chicken wire between your antenna and next floor down, ground
it, your house should be safe.
If you have a car with a metal roof, placing the antenna in the middle
of it will keep the RF out of your vehicle pretty effectively. Also
I think the highest mobile wattage is less than 100 watts, no?
If you obey the reg that says you should communicate at the minimum
wattage neccesary you will probably operate at well below that figure.
Assuming that it could actually cause cancer...
>There is statistically significant cancer rates above the non-electronic
>population.
Depends on how the data was calculated. Perhaps the HAM community
is significantly older that the population at large, perhaps if
there is genetic propensity to be a HAM there will also be a
genetic propensity for cancer.
The answer is that there is no real knowledge of this. This whole
thing came about because of the 'power line' scares of the late 80's
and the lady's claim that using a mototrola portable phone gave her
brain cancer (despite the prevalnece of cancer deaths in her family)>
There might be a corrollation, but that does not prove causation!
>What I want to hear out there is anyone who has done, or is knowledgeable
>of work done in this field...Let us know.
I am currently studying Electromagnetics for a graduate degree.
--
Brent Irvine callsign: n0rzu These personal opinions can
internet: b-ir...@uiuc.edu be yours for a modest licensing
aol: bear...@aol.com fee of $50.00
Gregory Lapin
>Hello.
>
>If this has been discussed before, I'm sorry, I haven't seen it.
>
>
>The ARRL handbook mentions that we should keep the face of an amp
>at least 24 " from our body, etc. Rigs, power supplies, antenna tuners,
>and antennas are also hazardous to our health when set too close to our
>body.
>
>So now my amp is approx 4 feet from me, and my open wire antenna tuner
>is now 7 feet from me. I'm also about 2 feet from the face of the rig.
>I'm hoping that will do the trick to be immune from cancer...
>
>They mention that attic antennas are a no-no, and it appears mobiling
>douses your body with an rf field big time.
>
>There is statistically significant cancer rates above the non-electronic
>population.
Statistics are funny things. If you take the often quoted Milham article
entitled: "Increased Mortality in Amateur Radio Operators Due to Lymphatic
and Hematopoietic Malignancies", the statistics show a slight increase in
the incidence of leukemia amongst hams in Washington State and California
over a 5 year period (36 deaths compared to an expected value of 29,
corresponding to a death rate for hams of 7.1 per 100,000 vs. the normal
population rate of 6.7 per 100,000). Pretty convincing?
Now look at deaths from all causes and find that hams had 2,485 compared to
an expected number of deaths of 3,479. Does this mean that if you are a
ham you have less chance of dying than others?
The data were suspect as well. The list of dead hams came from the Silent
Keys announcements in QST. Other ham data came from the FCC database.
There was no indication of operating habits (if at all), homebrewer vs
appliance operator, length of time as a ham, sex of the operator (he
eliminated female names manually), or other mitigating factors, except he
did get occupation from the death certificates (31% had electrically
related jobs).
The bottom line is that I put little stock in this study. The numbers are
too small and the data are too incomplete.
>What I want to hear out there is anyone who has done, or is knowledgeable
>of work done in this field...Let us know.
I am a professor of biomedical engineering and neurology. I study brain
tumors (mainly curing them, not causing them) but I am embarking on a study
with rats to see how their tumor growth is affected by rf.
>Regards,
>
>Marc
Greg Lapin KD9AZ
D.RODMAN
>In article <CJFF8...@spk.hp.com> dep...@spk.hp.com (Marc DePaul) writes:
>>
>>The ARRL handbook mentions that we should keep the face of an amp
>>at least 24 " from our body, etc. Rigs, power supplies, antenna tuners,
>>and antennas are also hazardous to our health when set too close to our
>>body.
>
from this equipment. Since it falls off rapidly from the source.
>It might be hazardous because of RF burns: if you stand too close
>to an emitting radar dish or high power antenna array you will get
>burns on your body. Lower power WILL heat your tissues a bit, though
>any claims of cancer are unsubstantiated and are probably bogus.
>
Bogus, hum. I suggest you review your course work regarding cellular
membrane theory and cancer promotion. Pay particular attention to
the information on soliton formation.
>>So now my amp is approx 4 feet from me, and my open wire antenna tuner
>>is now 7 feet from me. I'm also about 2 feet from the face of the rig.
>>I'm hoping that will do the trick to be immune from cancer...
>
>Well your tissues will probably be unheated (below the background
>level anyway...
>
>>They mention that attic antennas are a no-no, and it appears mobiling
>>douses your body with an rf field big time.
>
No question about RF and mobiling signals. Would you put an attic
antenna next to you and not worry just a little? If not you, how
about your wife. Maybe you would worry about your children?
>It would depend on how your house is shielded. If you were to put a
>layr of chicken wire between your antenna and next floor down, ground
>it, your house should be safe.
>
I do not know where you are getting this type of thinking, but
inspite of shielding, once you are in the near field of an antenna
there is not much you can do about exposure. I tell you what,
why don't you wrap your house with chicken wire and when you
are ready, I'll come out and measure the RF???
>If you have a car with a metal roof, placing the antenna in the middle
>of it will keep the RF out of your vehicle pretty effectively. Also
>I think the highest mobile wattage is less than 100 watts, no?
>If you obey the reg that says you should communicate at the minimum
>wattage neccesary you will probably operate at well below that figure.
>
>Assuming that it could actually cause cancer...
>
>>There is statistically significant cancer rates above the non-electronic
>>population.
>
>Depends on how the data was calculated. Perhaps the HAM community
>is significantly older that the population at large, perhaps if
>there is genetic propensity to be a HAM there will also be a
>genetic propensity for cancer.
>
>The answer is that there is no real knowledge of this. This whole
>thing came about because of the 'power line' scares of the late 80's
>and the lady's claim that using a mototrola portable phone gave her
>brain cancer (despite the prevalnece of cancer deaths in her family)>
>
There are currently a series of prospective and retrospective
articles appearing in the literature which point to the likely
relationship between some forms of cancer in children and proximity
to power lines. This is no scare tactic, I assure you.
>There might be a corrollation, but that does not prove causation!
>
>>What I want to hear out there is anyone who has done, or is knowledgeable
>>of work done in this field...Let us know.
>
>I am currently studying Electromagnetics for a graduate degree.
>
Actually, I co-authored the section in the ARRL handbook on the
RF safety things. It was written and reviewed by several of the
most respected scientists in the country who also just happpen
to be hams. The comments I have reviewed here are typical of
the general misunderstanding and ignorance on behalf of general
ham population. May I suggest a more thoughtful approach to posting
comments on this forum. I am tired of seeing it. Dave.
Ken Edwards
True that the hand-helds are 1/2 w, but the EM fields are much more intense
(literally right against your skull). The police handhelds typically are the 'walkie-talkie' style and they have also learned to point the antenna away from the body (head in particular), thereby greatly reducing the field intensity. The EM field intensity has an inverse square relationship with proximity.
We have through research seen various effects on the body at various frequencies. Example, your microwave is set at a particular frequency that
will excite water molecules, thereby creating heat. At 27 Mhz (CB frequencies), the EM field has an affect on the sleep center of the brain. Exteremly low audio frequencies can, well let's just say can have an GI reaction.
The most critical factors, IMHO, is the length of exposure. The individual from
Motorola on Eye-to-eye that claimed brain cancer from cell-phone use was also
testing prototype antennas. I strongly suspect he spent hours per day on
a cell-phone close to his head. Length of exposure is directly in the users
control.
There was an intresting related story several months ago about how some police
officers were developing prostrait (sp ?) cancer. They also linked it to
a practice of removing the radar gun from its mounting on the exterior of the
vechicle and keeping it between their legs (as to not alert motorists). They
were using the equipment in direct contrdiction to the manufacturer's recommendations.
Measuring biological effects of RF-EM radiation is itself somewhat contriversal.
The only agreed upon measurement (that I am aware of) is the change in temperature in tissue. It was shown in a seminar that I attended on the subject, that long term cell exposure will raise the brain tissue.
On the subject on research methods (which I know little about), here is a
humorous happening tht illustraits the complexity of the problem. A group of
researchers were studying the effects of RF on lab rats. They noticed when a
particlar frequency was used, the rats would run wildly until they eventually
sat in a water bowl. They concluded that this frequency had a effect on the rat's brain. Later in discussing their result, a radio engineer asked what the
frequency was, and after doing some calculation, found the rat's tail was a
perfect antenna for that frequency, hense, the tail was getting HOT !
There is much more that we don't know about RF-EM effects on biological systems
than we do know. In the meantime, the best thing to do is not panic, not ignore, but use good ol' common sense.
73s :)
--
======================================================================
Ken M. Edwards, PE Bell Northern Research, Research Triangle Park, NC
(919) 481-8476 email: cnc...@bnr.ca Ham: N4ZBB
All opinions are my own and do not necessarily reflect the views of
my employer or co-workers, family, friends, congress, or president.
(To the e-mail'r out there -> This is a short as it will gets)
Gary Coffman
>
>The ARRL handbook mentions that we should keep the face of an amp
>at least 24 " from our body, etc. Rigs, power supplies, antenna tuners,
>and antennas are also hazardous to our health when set too close to our
>body.
>
>So now my amp is approx 4 feet from me, and my open wire antenna tuner
>is now 7 feet from me. I'm also about 2 feet from the face of the rig.
>I'm hoping that will do the trick to be immune from cancer...
There's no such thing as immunity to cancer. The correlation between
low level RF exposure and cancer is weak at best, about 0.4 per 100,000
in the Milham study, and it had no controls for the other exposures that
hams suffer from electronic chemicals, lead vapor, etc. Other studies
have actually shown a *negative* correlation. And remember, correlation
does not equal causation. No in vivo controlled laboratory data exists
that shows any causation mechanism. There is some inconclusive evidence
from in vitro studies, but in vitro results often don't translate one to
one to in vivo results. There is very hard data, however, that exposure
to field power densities greater than 10 mw/cm^2 cause health problems,
not cancer, but rather things like cataracts. That's why you want to stay
out of the near field of radiating objects.
>They mention that attic antennas are a no-no, and it appears mobiling
>douses your body with an rf field big time.
Attic antennas can be a problem, particularly if you are running
significant power, but an antenna mounted in the center of the metal
roof of a car shouldn't expose you to signifcant fields. A through
the glass antenna, however, could make the entire passenger cabin hot
with RF, I have actual measurement data to prove that. Another reason
to avoid these poor performers.
>There is statistically significant cancer rates above the non-electronic
>population.
That's not clear at all. The Milham study shows a weak positive
correlation, but other studies either show no correlation, or a
negative correlation. The IBEW study of union electrical workers
actually shows a negative correlation despite the fact that many
electrical workers are also exposed to PCBs. Most of the studies of
childhood leukemia increases depended on *calculated* exposure
values. When control studies have been done with *measured* exposure
values, the correlation goes away.
>What I want to hear out there is anyone who has done, or is knowledgeable
>of work done in this field...Let us know.
John Moulder produced the EMF faq for sci.med. While it deals mainly
with power line radiation, it points out the pitfalls of blindly accepting
some of the studies often cited as evidence of increased cancer risk.
I'm appending it to the end of this post.
Gary
#include faq
_______________________________________________________________________
Power-Frequency Fields and Cancer (J. Moulder, v3, 22-Aug-93)
Notice: This FAQ sheet may be redistributed as long at remains correctly
attributed. If it is edited or condensed prior to redistribution, please add
a note to that effect.
1) Why is there a concern about power lines and cancer?
Most of the concern about power lines and cancer stems from epidemiological
studies of people living near distribution and transmission lines, and
epidemiological studies of people working in "electrical occupations". Some
of these epidemiological studies appear to show a relationship between
exposure to power-frequency fields and the incidence of cancer. Laboratory
studies have shown no link between power-frequency fields and cancer.
2) What's the difference between the electromagnetic [EM] energy associated
with power lines and other forms of EM energy such as microwaves or x-rays?
X-rays, ultraviolet (UV) light, visible light, infrared light, microwaves
(MW), radiowaves (RF), and magnetic fields from electrical power systems are
all parts of the EM spectrum. The parts of the EM spectrum are
characterized by their frequency or wavelength. The frequency and wave
length are related, and as the frequency rises the wavelength gets shorter.
The frequency is the rate at which the EM field changes direction and is
usually given in Hertz (Hz), where one Hz is one cycle per second.
Power-frequency fields in the US vary 60 times per second, so they are 60 Hz
fields, and have a wavelength of 3000 miles. Power in much of the rest of
the world is at 50 Hz. Broadcast AM radio has a frequency of around one
million Hz and wavelengths of around 1000 ft. Microwave ovens have a
frequency of about 2 billion Hz, and a wavelength of about 5 inches. X-rays
and UV light have frequencies of millions of billions of Hz, and wavelengths
of less than a thousandth of an inch.
3) What differences are there in the biological effects of these different
portions of the EM spectrum?
The interaction of biological material with an EM source depends on the
frequency of the source. We usually talk about the electromagnetic spectrum
as though it produced waves of energy. This is not strictly correct, because
sometimes electromagnetic energy acts like particles rather than waves; this
is particularly true at high frequencies. This double nature of the
electromagnetic spectrum is referred to as "wave-particle duality". The
particle nature of electromagnetic energy is important because it is the
energy per particle (or photons, as these particles are called) that
determines what biological effects electromagnetic energy will have.
At the very high frequencies characteristic of UV light and X-rays,
electromagnetic particles (photons) have sufficient energy to break chemical
bonds. This breaking of bonds is termed ionization, and this portion of the
electromagnetic spectrum is termed ionizing radiation. At lower frequencies,
such as those characteristic of visible light, radiowaves, and microwaves,
the photons don't carry enough energy to break chemical bonds; but they do
carry enough energy to cause molecules to vibrate, causing heating. These are
called thermal effects, and this portion of the electromagnetic spectrum is
termed the thermal, non-ionizing portion. Below the frequencies used in
commercial broadcast radio (such as the 60 Hz frequencies generated in the
production and distribution of electricity), the photons have insufficient
energy to cause heating, and this portion of the electromagnetic spectrum is
termed the non-thermal, non-ionizing portion.
4) What is difference between EM radiation and EM fields?
In general, EM sources produce both radiant energy (radiation) and non-
radiant energy (fields). Radiated energy exists apart from its source,
travels away from the source, and continues to exist even if the source is
turned off. Non-radiant energy is not projected away into space, and it
ceases to exist when the energy source is turned off. When a person or
object is more than several wavelengths from an EM source, a condition called
far-field, the radiation component of the EM fields dominates. In the far-
field the electrical and magnetic components are closely related. When a
person or object is less than one wavelength from an EM source, a condition
called near-field, the field effect dominates, and the electrical and
magnetic components are unrelated.
For ionizing frequencies where the wavelengths are less than thousandths of
an inch, human exposure is entirely in the far-field, and only the radiation
from the EM source is relevant to possible health effects. For MW and RF,
where the wavelengths are in inches and feet, human exposure can be in both
the near- and the far-field, so that both field and radiation effects are
relevant. For power-frequency fields, where the wavelength is thousands of
miles, human exposure is always in the near-field, and only the field
component is relevant to possible health effects.
5) How does ionizing EM sources cause biological effects?
Ionizing EM radiation carries sufficient energy to break chemical bonds. In
particular, ionizing radiation is capable of breaking bonds in the genetic
material of the cell, the DNA. Severe damage to DNA can kill cells,
resulting in tissue damage or death. Lesser damage to DNA can result in
permanent changes in the cells which may lead to cancer. If these changes
occur in reproductive cells, they can lead to inheritable changes, a
phenomena called mutation. All of the known hazards from exposure to the
ionizing portion of the EM spectrum are the result of the breaking of
chemical bonds in DNA. For frequencies below that of UV light, DNA damage
does not occur. Well-accepted safety standards exist to prevent significant
damage to the genetic material of persons exposed to ionizing EM radiation.
6) How do the thermal non-ionizing EM sources cause biological effects?
Visible light, MW, and RF can cause molecules to vibrate, causing heating.
This molecular heating can kill cells. If enough cells are killed an
organism will suffer a noticeable burn. Cells which are not killed by
heating are normal when the heating ceases. All of the known hazards from
exposure to the thermal non-ionizing portion of the EM spectrum are the
result of heating. For frequencies below about the middle of the AM
broadcast spectrum, this heating does not occur.
The molecular vibration caused by MW is how and why a MW oven works -
exposure of the food to the microwaves causes water molecules to vibrate and
get hot. MW and RF penetrate and heat best when the size of the object is
close to the wavelength. For the 2450 MHz (2.45 billion Hz) used in
microwave ovens the wavelength is 5 inches, a good match for most of what we
cook.
7) How do the power-frequency EM fields cause biological effects?
The electrical and magnetic fields associated with power-frequency fields
cannot break bonds or cause molecular heating. Thus the known mechanisms
through which ionizing radiation, MW and RF effect biological material have
no relevance for power-frequency fields.
The electrical fields associated with the power-frequency fields exist
whenever voltage is present. These electrical fields have very little
ability to penetrate buildings or even skin. The magnetic fields associated
with power-frequency fields exist only when current is flowing. These
magnetic fields are difficult to shield, and easily penetrate buildings and
people. Because power-frequency electrical fields do not penetrate, any
biological effects from routine exposure to power-frequency fields must be
due to the magnetic component of the field.
Exposure of people to power-frequency magnetic fields results in the
induction of electrical currents in the body. These currents are similar to
naturally-occurring currents. It requires a power-frequency magnetic field
in excess of 5 Gauss (see Q8 for typical exposures) to cause electrical
currents of a magnitude similar to those that occur naturally in the body.
Electrical currents that are above those that occur naturally in the body
can cause noticeable effects, including direct nerve stimulation. Well-
accepted safety standards exist to protect persons from exposure to power-
frequency fields that would induce such currents (see Q16).
8) What sort of power-frequency magnetic fields are common in residences and
workplaces?
In the US magnetic fields are commonly measured in Gauss (G). In the rest of
the world, they are measured in Tesla (T), were 10,000 gauss equals 1 Tesla.
Within the right-of-way (ROW) of a high voltage transmission line, fields can
approach 100 mG (0.1 G, 100 microT). At the edge of a high-voltage ROW, the
field will be 5-25 mG. Ten meters from a 12 kV distribution line will be
fields will be 2-10 mG. Actual fields depend on voltage, design and current.
Fields within residences vary from over 1000 mG near certain appliances to
less than 0.2 mG in the center of some rooms. Occupational exposures may
exceed 10 Gauss (e.g., induction furnaces, arc welding), but exposures in the
10-50 mG range are more common.
9) What is known about the relationship between powerline corridors and
cancer rates?
Some studies have shown that children (but not adults) living near certain
types of powerlines (high current distribution lines and transmission lines)
have higher than average rates of leukemia and brain cancers (Refs 1-3). The
correlation is not strong, and none of the studies have shown dose-response
curves. When power-frequency fields are actually measured, the correlation
vanishes (not surprising, since the major source of power-frequency fields
within most dwellings is inside the house). Several other studies have shown
no correlations (Refs 4-6).
10) How big is the "cancer risk" associated with living next to a powerline?
The excess cancer found in epidemiological studies is usually quantified in a
number called the relative risk (RR). This is the risk of an "exposed"
person getting cancer divided by the risk of an "unexposed" person getting
cancer. Since no one is unexposed to power-frequency fields, the comparison
is actually "high exposure" versus "low exposure". Relative risks are
generally given with 95% confidence intervals. These 95% confidence
intervals are almost never adjusted for multiple comparisons even when
multiple types of cancer and multiple indices of exposure are studied.
Taken together, using a technique known as "meta-analysis", the relative
risks for the residential exposure studies are (adapted from ref. 7):
childhood leukemia: 1.3 (0.8 - 2.1) 5 studies
childhood brain cancer: 2.4 (1.7 - 3.5) 3 studies
adult leukemia: 1.1 (0.9-1.4) 2 studies
all adult cancer: 1.2 (0.8-1.6) 2 studies
11) What is known about the relationship between "electrical occupations"
and cancer rates?
Several studies have shown that people who work in electrical occupations
have higher than average leukemia, lymphoma, and brain cancer rates (refs 8-
10). Most of the cautions listed for the residential studies apply here
also: many negative studies, weak correlations, no dose-response curves.
Additionally, these studies are mostly based on job titles, not on measured
exposures.
Taken together, using a technique known as "meta-analysis", the relative
risks for the occupational exposure studies are (adapted from ref. 7):
leukemia: 1.1 (1.0-1.2) 24 studies
brain: 1.2 (1.0-1.5) 16 studies
lymphoma: 1.2 (0.9-1.5) 6 studies
all cancer: 1.0 (0.9-1.1) 8 studies
12) What do laboratory studies tell us about power-frequency fields and
cancer?
Power-frequency fields show none of the classic signs of being carcinogens -
they do not cause DNA damage or chromosome breaks, and they are not mutagenic
(refs 11-15). No studies have shown that animals exposed to power-frequency
fields have increased cancer rates. On the other hand, numerous studies have
reported that power-frequency fields do have "effects", particularly at high
field strength (refs 16, 17). Even among the scientists who believe that
there may be a connection between power-frequency fields and cancer, there is
no consensus as to possible mechanisms (refs 16, 18).
There are agents that influence the development of cancer without directly
damaging the genetic material. It has been suggested that power-frequency
EMFs could either promote cancer or influence the progression of cancer. A
promoter is an agent that increases the cancer risk in an animals already
exposed to a genotoxic carcinogen. A progression effect would be one that
increased the growth rate of an existing tumor. Promotion studies of power-
frequency fields have been uniformly negative (refs 14, 19-21). Studies of
progression have been mixed: 75% show no effects on tumor growth, while the
rest are about equally mixed between studies showing increased growth and
studies showing decreased growth (refs 11, 15, 20-22).
13) What about the new "Swedish" study showing a link between power lines
and cancer?
There are new residential and occupational studies from both Sweden and
Denmark. None have been published in full, but translations of the
preliminary reports have been circulated.
- Fleychting & Ahlbom [Magnetic fields and cancer in people residing near
Swedish high voltage powerlines]. A case-control study of everyone who
lived within 300 meters of high-voltage powerlines between '60 and '85. For
children all types of tumors were analyzed, for adults only leukemia and
brain tumors were studied. "Exposure" was assessed by spot measurements,
calculated retrospective assessments, and distance from powerlines. No
increased overall cancer risk was found for either children or adults. An
increased risk for leukemia (but not other cancers) was found in children for
*calculated* fields at the time of diagnosis. No significantly elevated
cancer risks were found for measured fields or proximity to powerlines.
- Olsen and Nielson [Electromagnetic fields from high-power electricity
transmission systems and the risk of childhood cancer]. Case-control study
based on all childhood leukemia, brain tumors and lymphomas diagnosed in
Denmark between '68 and '86. "Exposure" was assessed on the basis of
calculated fields over the period from conception to diagnosis. No overall
increase in cancer risk was found, but the risk of lymphoma was elevated. No
increase in childhood leukemia or brain cancer was found.
- Guenel et al. [Cancer incidence among Danish persons who have been exposed
to magnetic fields at work]. Case-control study based on all cancer in
actively employed Danes between '70 and '87 who were 20-64 years old in 1970.
Each occupation-industry combination was coded on the basis of supposed 50-Hz
magnetic field exposure. No significant increases in risk were seen for
breast cancer, malignant lymphomas or brain tumors. Leukemia incidence was
elevated among men in the highest "exposure" category; women in similar
exposure categories showed no excess risk.
-Floderus et al [Occupational exposure to EM fields in relation to leukemia
and brain tumors]. Case-control study of leukemia and brain tumors of men,
20-64 years of age in '80. "Exposure" calculations were based on the job
held longest during the 10-year period prior to diagnosis. Many measurements
were taken using a person whose job was most similar to that of the person in
the study. About two thirds of the subjects in the study could be assessed in
this manner. A significantly elevated risk was found for leukemia, but not
for brain cancer.
14) How do scientists evaluate all the confusing and contradictory
laboratory and epidemiological studies of power-frequency magnetic fields and
cancer?
There are certain widely accepted criteria that are weighed when assessing
such groups of studies. These are the Hill criteria (ref. 23).
- First, what is the *strength of the association* between exposure and risk;
is there a clear risk associated with exposure? A strong association is one
with a RR (see Q9) of 5 or more. Tobacco smoking, for example, shows a RR
for lung cancer of 10-30 times that of non-smokers.
Most of the positive power-frequency studies have RRs of less than two. The
leukemia studies as a group have RRs of about 1.2, while the brain cancer
studies as a group have RRs of about 2. This is only a weak association.
- Second, are there many *consistent studies* indicating the same risk; do
most studies show about the same risk for the same disease? Using the same
example, essentially all studies of smoking and cancer showed an increased
risk for lung and head-and-neck cancers.
Many power-frequency studies show statistically significant risks for some
types of cancers and some types of exposures, but many do not. Even the
positive studies are inconsistent with each other. For example, while a new
Swedish study shows an increased risk for childhood leukemia for one measure
of exposure, it contradicts prior studies that showed a risk for brain
cancers, and a parallel Danish study shows a risk for childhood lymphomas,
but not for leukemia. Many of the studies are internally inconsistent. For
example, where the Swedish study shows an increased risk for childhood
leukemia, it shows no overall increase in childhood cancer, implying that the
rates of other types of cancer are decreased. In summary, few show the same
positive result, so that the consistency is quite weak.
- Third, is there evidence for a *dose-response relationship*; does risk
increase when the exposure increases? Again, the more a person smokes, the
higher the risk of lung cancer.
No power-frequency exposure studies have shown a dose-response relationship
between measured fields and cancer rates, or between distances from
transmission lines and cancer rates. The lack of a relationship between
exposure and increased cancer risk is a major reason why many scientists are
skeptical about the significance of the epidemiology.
- Fourth, is there *laboratory evidence* suggesting that there is a risk
associated with such exposure? Epidemiological associations are greatly
strengthened when we have laboratory evidence for a risk. When the US
Surgeon General first stated that smoking caused lung cancer, the laboratory
evidence was ambiguous. We knew that cigarette smoke and tobacco contained
carcinogens, but no one had been able to make lab animals get cancer by
smoking.
Power-frequency fields show none of the effects on cells, tissues or animals
that point towards their being a cause of cancer, or to their contributing to
cancer.
-Fifth, are there *plausible biological mechanisms* that suggest that there
should be a risk? If we understand how something causes disease, it is much
easier to interpret ambiguous epidemiology. With smoking, for example, the
fact that there were known cancer-causing agents in tobacco made it very easy
to believe the epidemiology.
>From what we know of power-frequency fields and their effects on biological
systems we have no reason to even suspect that they pose a risk to people at
the exposure levels associated with the generation and distribution of
electricity.
- Overall the evidence for a connection between power frequency fields and
cancer is at most weak, because of the weakness and inconsistencies in the
epidemiological studies, combined with the lack of a dose-response
relationship in the human studies, and the negative laboratory studies
15) What are some good overview articles?
A very good review of the area has just been published by Oak Ridge
Associated Universities. It is titled "Health Effects of Low-Frequency
Electric and Magnetic Fields". It costs $25 and is available from National
Technical Information Service (ARAU 92/F-8) and the US Government Printing
Office (029-000-00443-9). If you're in the U.K., a good review is: R Doll et
al, Electromagnetic Fields and the Risk of Cancer, National Radiation
Protection Board, Chilton, 1992. Another good review is MN Bates,
"Extremely low frequency electromagnetic fields and cancer: the
epidemiologic evidence", in Environmental Health Perspectives 95:147-156,
1991.
16) Are there exposure standards for power-frequency fields?
Yes, a number of governmental and professional organizations have developed
exposure standards. These standards are based on keeping the body currents
induced by power-frequency EM fields to a level below the naturally occurring
fields. The most generally relevant are:
- Guidance as to restriction on exposures to time varying EM fields and the
1988 recommendations on the International Non-Ionizing Radiation Committee,
National Radiation Protection Board, Chilton, 1989.
50/60 Hz E-field: ~10 kV/m (freq. dependent)
50/60 Hz H-field: 1630 A/m, 2 mT (20 G)
- Sub-radiofrequency (30 KHz and below) magnetic fields, In: Documentation of
the threshold limit values, American Committee of Government and Industrial
Hygienists, pp. 55-64,1992.
At 60 Hz: 1 mT (10 G); 0.1 mT (1 G) for pacemaker wearers
- HP Jammet et al: Interim guidelines on limits of exposure to 50/60 Hz
electric and magnetic fields. Health Physics 58:113-122, 1990.
*H-field (rms)
24 hr general public: 0.1 mT = 1 G
Short-term general public: 1 mT = 10 G
Occupational continuous: 0.5 mT = 5 G
Occupational short-term: 5 mT = 50 G
*E-field (rms)
24 hr general public: 5 kV/m
Short-term general public: 10 kV/m
Occupational continuous: 10 kV/m
Occupational short-term: 30 kV/m
-----------------------
References:
1) N Wertheimer & E Leeper: Electrical wiring configurations and childhood
cancer. Amer J Epidemiol 109:273-284, 1979.
2) DA Savitz et al: Case-control study of childhood cancer and exposure to 60-
Hz magnetic fields. Amer J Epidemiol 128:21-38, 1988.
3) SJ London et al: Exposure to residential electric and magnetic fields and
risk of childhood leukemia. Amer J Epidemiol 134:923-937, 1991.
4) MP Coleman et al: Leukemia and residence near electricity transmission
equipment: a case-control study. Br J Cancer 60:793-798, 1989.
5) ME McDowall: Mortality of persons resident in the vicinity of electrical
transmission facilities. Br J Cancer 53:271-279, 1986.
6) A Myers et al: Childhood cancer and overhead powerlines: a case-control
study. Brit J Cancer 62:1008-1014, 1990.
7) G.B. Hutchison: Cancer and exposure to electric power. Health Environ
Digest 6:1-4, 1992.
8) M Coleman & V Beral: A review of epidemiological studies of the health
effects of living near or working with electrical generation and transmission
equipment. Int J Epidemiol 17:1-13, 1988.
9) JR Jauchem & JH Merritt: The epidemiology of exposure to EM fields: an
overview of the recent literature. J Clin Epidemiol 44:895-906, 1991.
10) DA Savitz & EE Calle: Leukemia and occupational exposure to EM fields:
Review of epidemiological studies. J Occup Med 29:47-51, 1987.
11) GK Livingston et al: Reproductive integrity of mammalian cells exposed to
power frequency EM fields. Environ Molec Mutat 17:49-58, 1991.
12) M Rosenthal & G Obe: Effects of 50-Hertz EM fields on proliferation and
on chromosomal aberrations in human peripheral lymphocytes untreated and
pretreated with chemical mutagens. Mutat Res 210:329-335, 1989.
13) J. Nafziger et al: DNA mutations and 50 Hz EM fields. Bioelec Bioenerg
30:133-141, 1993.
14) A. Rannug et al: A study on skin tumor formation in mice with 50 Hz
magnetic field exposure. Carcinogenesis 14:573-578, 1993.
15) R. Zwingelberg et al: Exposure of rats of a 50-Hz, 30-mT magnetic field
influences neither the frequencies of sister-chromatid exchanges nor
proliferation characteristics of cultured peripheral lymphocytes. Mutat Res
302:39-44, 1993.
16) TS Tenforde: Biological interactions and potential health effects of
extremely-low-frequency magnetic fields from power lines and other common
sources. Ann Rev Publ Health 13:173-196, 1992.
17) R Goodman & A Shirley-Henderson: Transcription and translation in cells
exposed to extremely low frequency EM fields. Bioelec Bioenerg 25:335-355,
1991.
18) RB Goldberg & WA Creasey: A review of cancer induction by extremely low
frequency EM fields. Is there a plausible mechanism? Medical Hypoth 35:265-
274, 1991.
19) A Rannug et al: Rat liver foci study on coexposure with 50 Hz magnetic
fields and known carcinogens. Bioelectromag 14:17-27, 1993.
20) MA Stuchly et al: Modification of tumor promotion in the mouse skin by
exposure to an alternating magnetic field. Cancer Letters 65:1-7, 1992.
21) JRN McLean et al: Cancer promotion in a mouse-skin model by a 60-Hz
magnetic field: II. Tumor development and immune response. Bioelectromag
12:273-287, 1991.
22) S Baumann et al: Lack of effects from 2000-Hz magnetic fields on mammary
adenocarcinoma and reproductive hormones in rats. Bioelectromag 10:329-333,
1989.
23) AB Hill: The environment and disease: Association or causation? Proc
Royal Soc Med 58:295-300, 1965.
John Moulder (jmou...@its.mcw.edu) Voice: 414-266-4670
Radiation Biology Group FAX: 414-257-5033
Medical College of Wisconsin, Milwaukee
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | |
Barry x24904/ER/167B-TED
>We have through research seen various effects on the body at various
>frequencies. Example, your microwave is set at a particular frequency that
>will excite water molecules, thereby creating heat.
This is a common misconception and one that needs to be corrected, especially
in regard to a discussion on how radio waves interact with living cells.
The lowest resonant absorption frequency for water (rotational spectra) is
22.235 GHz. Home microwave ovens in the United States operate at 2.45 GHz.
Industrial ovens often use 916 MHz. In Europe, other frequencies are often
used such as 433.9 and 896 MHz (UK), 2.375 GHz (former USSR), 3.39 GHz
(Netherlands), etc. None of these frequencies specifically excite water
molecules. Water has a high dielectric constant and high dielectric losses
from low frequencies to well into the microwave region (8 to 18 GHz depending
on many factors). Many other materials also are good absorbers of microwave
energy in this part of the spectrum: ethanol (drinking alcohol), methanol
(Wood alcohol), acetone (fingernail polish remover), ethylene glycol
(antifreeze), etc. Ice, however, is a relatively poor absorber of microwaves.
Many plastics such as Nylon and ceramics such as Steatite are also good
microwave absorbers at elevated temperatures (in fact Nylon and Steatite can
undergo thermal runaway). The frequency of 2.45 GHz was chosen by international
agreement. It is a reasonable compromise of a number of factors: magnetrons
are relatively inexpensive for this part of the spectrum, the absorption of
most foods is high at this frequency yet not so high that penetration becomes
a problem, and the dimensions of a multimode cavity cooking chamber are
reasonable for most kitchens.
A good reference on how microwaves interact with materials is "Microwave
Spectroscopy" by Townes and Schawlow. [This is the same Charles Townes of
maser and laser fame.] A more practical reference is "Industrial Microwave
Heating" by Metaxas and Meredith. I believe both of these books are still
in print.
73, Barry WA4VZQ
-----------------
| ___ ________ | Dr. Barry L. Ornitz WA4VZQ
| | / / | | Eastman Chemical Company
| | / / | | ECC Research Laboratories, Engineering Research Div.
| |< < K O D A K| | Process Instrumentation Research Laboratory
| | \ \ | | P. O. Box 1972, Building 167B
| |__\ \________| | Kingsport, TN 37662 (615/229-4904, FAX 615/229-4558)
| | INTERNET: orn...@kodak.com
-----------------
Eastman Chemical Company is no longer a part of Kodak. Until we have our
own Internet connection, Kodak is graciously letting us continue to use theirs.
Rajiv Dewan
Gary Coffman <ga...@ke4zv.atl.ga.us> included a FAQ on radiation.
Thanks for including it Gary. I enjoyed reading it and learnt a lot
from it. The following paragraph about microwave ovens caught my attention:
>The molecular vibration caused by MW is how and why a MW oven works -
>exposure of the food to the microwaves causes water molecules to vibrate and
>get hot. MW and RF penetrate and heat best when the size of the object is
>close to the wavelength. For the 2450 MHz (2.45 billion Hz) used in
>microwave ovens the wavelength is 5 inches, a good match for most of what we
>cook.
And I thought that this frequency was picked because it was close to
a resonant frequencty of the O-H bond present in water, sugars and fats -
common though often undesired components of what we eat.
Rajiv
aa9ch
Gary Coffman
That's true. The faq is saying two separate things here. First it's
noting that 2.45 GHz excites water molecules. And second it's saying
that an object tends to absorb RF best when the wavelength, actually
*half* wavelength, matches the size of the object. That's because
maximum E (or H) field difference is developed across it.
Note: 2.45 GHz is *not* a resonant frequency for water molecules,
but water does absorb significantly at this frequency.
Gary
Bill Chiarchiaro
In article <1994Jan11.1...@kodak.rdcs.kodak.com>, orn...@kodak.rdcs.kodak.com (Barry x24904/ER/167B-TED) writes:
|>
|> ...stuff deleted...
|>
|> This is a common misconception and one that needs to be corrected,
|> especially in regard to a discussion on how radio waves interact with
|> living cells.
|>
|> The lowest resonant absorption frequency for water (rotational
|> spectra) is 22.235 GHz. Home microwave ovens in the United States
|> operate at 2.45 GHz.
|>
|>
I agree with Barry that the common microwave oven frequency of
2.45 GHz does not correspond to a resonance of the water molecule. I
also agree that the lowest resonance for water is around 22 GHz.
However, that resonance is exhibited by _gaseous water_.
So far as I know, neither liquid water nor ice exhibit any RF
rotational resonances, but I'm not certain.
By the way, the dielectric loss factor of pure, liquid water does
show a peak at about 1 GHz at 0 Celsius, moving up to about 10 GHz at
+20 Celsius. Sea water shows a rather constant loss factor over
that frequency range (pretty much the same at 0 and +20 Celsius),
increasing at lower frequencies and falling at higher frequencies.
These are my recollections from data presented in an appendix to
Volume 3 of _Microwave Remote Sensing_ by Ulaby et. al.
73
Bill Chiarchiaro N1CPK
w...@ll.mit.edu
Mark Zenier
: And I thought that this frequency was picked because it was close to
: a resonant frequencty of the O-H bond present in water, sugars and fats -
: common though often undesired components of what we eat.
Water is a polar molecule because of its shape and applying a
electric field causes the entire molecule to attempt to align
to the field.
o ___ axis of rotation
h h
Mark Zenier mze...@eskimo.com ma...@ssc.com
Mark G. Salyzyn
>irv...@uxh.cso.uiuc.edu (Brent Irvine) writes...
>>It would depend on how your house is shielded. If you were to put a
>>layr of chicken wire between your antenna and next floor down, ground
>>it, your house should be safe.
>>
>I do not know where you are getting this type of thinking, but
>inspite of shielding, once you are in the near field of an antenna
>there is not much you can do about exposure. I tell you what,
>why don't you wrap your house with chicken wire and when you
>are ready, I'll come out and measure the RF???
:-)
Please notice that all stucko houses are covered in chicken wire ...
*when* I had RF in the shack, it could be traced directly to radiation from
the ground wire (inside my chicken wire encased house). I have an RF clean
room in my house, a closet completely covered with chicken wire, and because
it is in the basement, the ground rod is immediately drilled into the cement,
it effectively shields RF from getting in and out! I will be building the bomb
shelter out back next ... I wonder if this is the first sign of the disease of
Ham Radio ...
Ciao, 73 de VE6MGS/Mark -sk-
"He's everywhere, He's everywhere ... Chicken Maaaaaaaaaannnnnnnn"
Leland Van Koten
>John Moulder produced the EMF faq for sci.med. While it deals mainly
>with power line radiation, it points out the pitfalls of blindly accepting
>some of the studies often cited as evidence of increased cancer risk.
>I'm appending it to the end of this post.
>
>Gary
Thanks for the very informative post. Although it is impossible to say with
certainty that there is NO risk, from EMR, it is clear that if there IS a risk,
it is a very low one. When one compares the possible risk from EMR to very
clear and significant risks that we all take every day, any risk is obviously
insignificant.
Interestingly, a clearly documented producer of cancer in both animals and
humans is excess caloric intake, and when I look around a lot of hamfests, if
there is excess cancer in hams, that may be the reason rather than exposure to
EMR. None of the power line studies of which I am aware have been
adequately controlled for such things as socio-economic status, etc., but
places such as New Jersey are apparently nevertheless rushing to impose taxes
on emitters of EMR on the theory that EMR is carcinogenic. I have even heard
predictions that EMR litigation will be the "new asbestos litigation."
Let's hope that the news media don't feed the sense of hysteria that many
people feel when confronted by something they don't understand, and that we dt
end up spending billions of dollars dealing with a problem that may not even
exist.
Lee/KE3FB in Md.
leeva...@delphi.com
Gary Coffman
>
>Thanks for the very informative post. Although it is impossible to say with
>certainty that there is NO risk, from EMR, it is clear that if there IS a risk,
>it is a very low one. When one compares the possible risk from EMR to very
>clear and significant risks that we all take every day, any risk is obviously
>insignificant.
That's absolutely true. People need to get a grasp of proportion when
it comes to evaluating risks. There's no such thing as a risk free activity
or product, but ham radio is safer than skydiving, or driving a car. It's
probably safer than drinking milk, certainly safer than taking asprin.
This is a case similar to nuclear power. The risks of nuclear power are
tiny compared to the known risks of coal fired generation, yet the latter
is accepted while the former is feared. The *possibility* of an invisible
threat frightens the ignorant more than the visible threat of the known.
>Interestingly, a clearly documented producer of cancer in both animals and
>humans is excess caloric intake, and when I look around a lot of hamfests, if
>there is excess cancer in hams, that may be the reason rather than exposure to
>EMR.
Actually, it's dietary fat intake that's the supposed risk factor, not
the calories themselves. On the other hand, Eskimos have the lowest
incidence of heart disease and colon cancer of any studied group, and
their diet is extremely high in fat. Go figure.
>None of the power line studies of which I am aware have been
>adequately controlled for such things as socio-economic status, etc., but
>places such as New Jersey are apparently nevertheless rushing to impose taxes
>on emitters of EMR on the theory that EMR is carcinogenic. I have even heard
>predictions that EMR litigation will be the "new asbestos litigation."
>
>Let's hope that the news media don't feed the sense of hysteria that many
>people feel when confronted by something they don't understand, and that we dt
>end up spending billions of dollars dealing with a problem that may not even
>exist.
This is one case where the media, at least the electronic media, is going
to tread very lightly. Their own ox is being gored here.
Gary
Jeffrey Hulten
would be low because we all understand the dangers. I would think
looking at the use of cellular phones (by people who don't have a clue)
and see if you can correlate cell phone use with brain tumors. I can see
twenty years from now a ton of lawsuits against McCaw Cellular because
the product didn't carry a warning label..
SURGEON GENERAL WARNING!
Using cellular phones may
cause brain cancer!!!
:)
====================================================================
= Jeffrey E. Hulten N 7 Y H L (Tech +) =
= jhu...@u.washington.edu Media Services =
= Bothell, WA 98012 University of Washington - Bothell =
= PGP Public Key availible via Finger or Keyservers. =
= Fingerprint : 89 95 AA BD BD 4F CE AE FD FC B7 AD F8 C5 AF 40 =
====================================================================
Gilbert Baron
>Let's hope that the news media don't feed the sense of hysteria that many
>people feel when confronted by something they don't understand, and that we
Did you see Wayne Greens drivel in his latest editorial in 73 on this
subject. It almost makes me ashamed that I have a lifetime subscription. He
even says it can do good too. It can cure aids he says. Very easily he says.
Why doesn't he develop it and make his millions?
Gil Baron, El Baron Rojo, W0MN Rochester,MN
"Bailar es Vivir"
PGP2.3 key at key servers or upon request
Jukka Salomaa
much 2m repeater OH2RAA in Helsinki.
--
Jukka Salomaa ju...@clinet.fi OH2BUA
phone +358 400 315 444 puhelin 9400 315 444