From: ehare@arrl.org (Ed Hare - KA1CV)
Newsgroups: rec.radio.amateur.misc
Subject: Re: Ham Radio Causes Cancer!
Date: 23 Jan 93 12:13:52 EST
Organization: American Radio Relay League

In rec.radio.amateur.misc, alanb@hpnmdla.sr.hp.com (Alan Bloom) writes:

>Some time ago, several people asked me for a copy of Dr Milham's
>famous paper supposedly showing that amateur radio causes cancer.
>I recently found my copy, so if anyone wants me to photocopy it for
>them, send me an SASE (with a note about what it's for!)

>I also wrote an article for our local ham club newsletter debunking
>the article.  If there's interest, I'll see if I can find it and
>post it.

>AL N1AL

Here is the information from the ARRL Handbook on the subject. It is one
of the more popular file requests for our Technical Information Service
and our Information Mail Server (info@arrl.org). This was
written by the Chairman of the ARRL Bioeffects commitee, Dr. Ivan
Shulman, MD (WC2S):

Reprinted from The 1992 ARRL Handbook chapter 36

Copyright 1992 American Radio Relay League, Inc.
All rights reserved.

Thank you for requesting the following information from the ARRL 
Information mail server. ARRL HQ is glad to provide this information
free of charge as a service to League members and affiliated clubs.

For your convenience, you may reproduce this information, electronically
or on paper, and distribute it to anyone who needs it, provided that
you reproduce it in its entirety and do so free of charge. Please note
that you must reproduce the information as it appears in the original,
including the League's copyright notice.

If you have any questions concerning the reproduction or distribution 
of this material, please contact Mark Wilson, American Radio Relay
League, 225 Main St., Newington, CT 06111 (mwilson@arrl.org).

RF Radiation Safety

Although Amateur Radio is basically a safe activity, in recent 
years there has been considerable discussion and concern about 
the possible hazards of electromagnetic radiation (EMR), 
including both RF energy and power frequency (50-60 Hz) 
electromagnetic fields. xtensive research on this topic is under 
way in many countries. This section was prepared by members of 
the ARRL Committee on the Biological Effects of RF Energy ("Bio 
Effects" Committee) and coordinated by Wayne Overbeck, N6NB. It 
summarizes what is now known and offers safety precautions based 
on the research to date. 

All life on earth has adapted to survive in an environment of 
weak, natural low-frequency electromagnetic fields (in addition 
to the earth's static geomagnetic field). Natural low-frequency 
EM fields come from two main sources: the sun, and thunderstorm 
activity. But in the last 100 years, manmade fields at much 
higher intensities and with a very different spectral 
distribution have altered this natural EM background in ways that 
are not yet fully understood. Much more research is needed to 
assess the biological effects of EMR. 

Both RF and 60-Hz fields are classified as nonionizing radiation 
because the frequency is too low for there to be enough photon 
energy to ionize atoms. Still, at sufficiently high power 
densities, EMR poses certain health hazards. It has been known 
since the early days of radio that RF energy can cause injuries 
by heating body tissue. In extreme cases, RF-induced heating can 
cause blindness, sterility and other serious health problems. 
These heat-related health hazards may be called thermal effects. 
But now there is mounting evidence that even at energy levels too 
low to cause body heating, EMR has observable biological effects, 
some of which may be harmful. These are athermal effects. 

In addition to the ongoing research, much else has been done to 
address this issue. For example, the American National Standards 
Institute, among others, has recommended voluntary guidelines to 
limit human exposure to RF energy. And the ARRL has established 
the Bio Effects Committee, a committee of concerned medical 
doctors and scientists, serving voluntarily to monitor scientific 
research in this field and to recommend safe practices for radio 
amateurs. 

Thermal Effects of RF Energy

Body tissues that are subjected to very high levels of RF energy 
may suffer serious heat damage. These effects depend upon the 
frequency of the energy, the power density of the RF field that 
strikes the body, and even on factors such as the polarization of 
the wave.

At frequencies near the body's natural resonant frequency, RF 
energy is absorbed more efficiently, and maximum heating occurs. 
In adults, this frequency usually is about 35 MHz if the person 
is grounded, and about 70 MHz if the person's body is insulated 
from ground. Also, body parts may be resonant; the adult head, 
for example, is resonant around 400 MHz, while a baby's smaller 
head resonates near 700 MHz. Body size thus determines the 
frequency at which most RF energy is absorbed. As the frequency 
is increased above resonance, less RF heating generally occurs. 
However, additional longitudinal resonances occur at about 1 GHz 
near the body surface.

Nevertheless, thermal effects of RF energy should not be a major 
concern for most radio amateurs because of the relatively low RF 
power we normally use and the intermittent nature of most amateur 
transmissions. Amateurs spend more time listening than 
transmitting, and many amateur transmissions such as CW and SSB 
use low-duty-cycle modes. (With FM or RTTY, though, the RF is 
present continuously at its maximum level during each 
transmission.)  In any event, it is rare for radio amateurs to be 
subjected to RF fields strong enough to produce thermal effects 
unless they are fairly close to an energized antenna or 
unshielded power amplifier. Specific suggestions for avoiding 
excessive exposure are offered later.

Athermal Effects of EMR     

Nonthermal effects of EMR, on the other hand, may be of greater 
concern to most amateurs because they involve lower-level energy 
fields. In recent years, there have been many studies of the 
health effects of EMR, including a number that suggest there may 
be health hazards of EMR even at levels too low to cause 
significant heating of body tissue. The research has been of two 
basic types: epidemiological research, and laboratory research 
into biological mechanisms by which EMR may affect animals or 
humans.

Epidemiologists look at the health patterns of large groups of 
people using statistical methods. A series of epidemiological 
studies has shown that persons likely to have been exposed to 
higher levels of EMR than the general population (such as persons 
living near power lines or employed in electrical and related 
occupations) have higher than normal rates of certain types of 
cancers. For example, several studies have found a higher 
incidence of leukemia and lymphatic cancer in children living 
near certain types of power transmission and distribution lines 
and near transformer substations than in children not living in 
such areas. These studies have found a risk ratio of about 2, 
meaning the chance of contracting the disease is doubled. (The 
bibliography at the end of this chapter lists some of these 
studies. See Wertheimer and Leeper, 1979, 1982; Savitz et al, 
1988).

Parental exposures may also increase the cancer risk of their 
offspring. Fathers in electronic occupations who are also exposed 
to electronic solvents have children with an increased risk of 
brain cancer (Johnson and Spitz, 1989), and children of mothers 
who slept under electric blankets while pregnant have a 2.5 risk 
ratio for brain cancer (Savitz et al, 1990).

Adults whose occupations expose them to strong 60-Hz fields (for 
example, telephone line splicers and electricians) have been 
found to have about four times the normal rate of brain cancer 
and male breast cancer (Matanoski et al, 1989). Another study 
found that microwave workers with 20 years of exposure had about 
10 times the normal rate of brain cancer if they were also 
exposed to soldering fumes or electronic solvents (Thomas et al, 
1987). Typically, these chemical factors alone have risk ratios 
around 2.

Dr. Samuel Milham, a Washington state epidemiologist, conducted a 
large study of the mortality rates of radio amateurs, and found 
that they had statistically significant excess mortality from one 
type of leukemia and lymphatic cancer. Milham suggested that this 
could result from the tendency of hams to work in electrical 
occupations or from their hobby.

However, epidemiological research by itself is rarely conclusive. 
Epidemiology only identifies health patterns in groups--it does 
not ordinarily determine their cause. And there are often 
confounding factors: Most of us are exposed to many different 
environmental hazards that may affect our health in various ways. 
Moreover, not all studies of persons likely to be exposed to high 
levels of EMR have yielded the same results.

There has also been considerable laboratory research about the 
biological effects of EMR in recent years. For example, it has 
been shown that even fairly low levels of EMR can alter the human 
body's circadian rhythms, affect the manner in which cancer-
fighting T lymphocytes function in the immune system, and alter 
the nature of the electrical and chemical signals communicated 
through the cell membrane and between cells, among other things. 
(For a summary of some of this research, see Adey, 1990.)

Much of this research has focused on low-frequency magnetic 
fields, or on RF fields that are keyed, pulsed or modulated at a 
low audio frequency (often below 100 Hz). Several studies 
suggested that humans and animals can adapt to the presence of a 
steady RF carrier more readily than to an intermittent, keyed or 
modulated energy source. There is some evidence that while EMR 
may not directly cause cancer, it may sometimes combine with 
chemical agents to promote its growth or inhibit the work of the 
body's immune system.

None of the research to date conclusively proves that low-level 
EMR causes adverse health effects. Although there has been much 
debate about the meaning and significance of this research, many 
medical authorities now urge "prudent avoidance" of unnecessary 
exposure to moderate or high-level electromagnetic energy until 
more is known about this subject.

Safe Exposure Levels     

How much EM energy is safe?  Scientists have devoted a great deal 
of effort to deciding upon safe RF-exposure limits. This is a 
very complex problem, involving difficult public health and 
economic considerations. The recommended safe levels have been 
revised downward several times in recent years--and not all 
scientific bodies agree on this question even today. In early 
1991, a new American National Standards Institute (ANSI) 
guideline for recommended EM exposure limits is on the verge of 
being approved (see bibliography). If the new standard is 
approved by a committee of the Institute of Electrical and 
Electronic Engineers (IEEE), it will replace a 1982 ANSI 
guideline that permitted somewhat higher exposure levels. ANSI-
recommended exposure limits before 1982 were higher still.

This new ANSI guideline recommends frequency-dependent and time-
dependent maximum permissible exposure levels. Unlike earlier 
versions of the standard, the 1991 draft recommends different RF 
exposure limits in controlled environments (that is, where energy 
levels can be accurately determined and everyone on the premises 
is aware of the presence of EM fields) and in uncontrolled 
environments (where energy levels are not known or where some 
persons present may not be aware of the EM fields).

Fig. 20 is a graph depicting the new ANSI standard. It is 
necessarily a complex graph because the standards differ not only 
for controlled and uncontrolled environments but also for 
electric fields (E fields) and magnetic fields (H fields). 
Basically, the lowest E-field exposure limits occur at 
frequencies between 30 and 300 MHz. The lowest H-field exposure 
levels occur at 100-300 MHz. The ANSI standard sets the maximum 
E-field limits between 30 and 300 MHz at a power density of 1 
mW/cm\2/ (61.4 volts per meter) in controlled environments--but 
at one-fifth that level (0.2 mW/cm\2/ or 27.5 volts per meter) in 
uncontrolled environments. The H-field limit drops to 1 mW/cm\2/ 
(0.163 ampere per meter) at 100-300 MHz in controlled 
environments and 0.2 mW/cm\2/ (0.0728 ampere per meter) in 
uncontrolled environments. Higher power densities are permitted 
at frequencies below 30 MHz (below 100 MHz for H fields) and 
above 300 MHz, based on the concept that the body will not be 
resonant at those frequencies and will therefore absorb less 
energy.

In general, the proposed ANSI guideline requires averaging the 
power level over time periods ranging from 6 to 30 minutes for 
power-density calculations, depending on the frequency and other 
variables. The ANSI exposure limits for uncontrolled environments 
are lower than those for controlled environments, but to 
compensate for that the guideline allows exposure levels in those 
environments to be averaged over much longer time periods 
(generally 30 minutes). This long averaging time means that an 
intermittently operating RF source (such as an Amateur Radio 
transmitter) will show a much lower power density than a 
continuous-duty station for a given power level and antenna 
configuration.

Time averaging is based on the concept that the human body can 
withstand a greater rate of body heating (and thus, a higher 
level of RF energy) for a short time than for a longer period. 
However, time averaging may not be appropriate in considerations 
of nonthermal effects of RF energy.

The ANSI guideline excludes any transmitter with an output below 
7 watts because such low-power transmitters would not be able to 
produce significant whole-body heating. (However, recent studies 
show that handheld transceivers often produce power densities in 
excess of the ANSI standard within the head).

There is disagreement within the scientific community about these 
RF exposure guidelines. The ANSI guideline is still intended 
primarily to deal with thermal effects, not exposure to energy at 
lower levels. A growing number of researchers now believe 
athermal effects should also be taken into consideration. Several 
European countries and localities in the United States have 
adopted stricter standards than the proposed ANSI guideline.

Another national body in the United States, the National Council 
for Radiation Protection and Measurement (NCRP), has also adopted 
recommended exposure guidelines. NCRP urges a limit of 0.2 
mW/cm\2/ for nonoccupational exposure in the 30-300 MHz range. 
The NCRP guideline differs from ANSI in two notable ways: It 
takes into account the effects of modulation on an RF carrier, 
and it does not exempt transmitters with outputs below 7 watts.

Low-Frequency Fields     

Recently much concern about EMR has focused on low-frequency 
energy, rather than RF. Amateur Radio equipment can be a 
significant source of low-frequency magnetic fields, although 
there are many other sources of this kind of energy in the 
typical home. Magnetic fields can be measured relatively 
accurately with inexpensive 60-Hz dosimeters that are made by 
several manufacturers.

Table 3 shows typical magnetic field intensities of Amateur Radio 
equipment and various household items. Because these fields 
dissipate rapidly with distance, "prudent avoidance" would mean 
staying perhaps 12 to 18 inches away from most Amateur Radio 
equipment (and 24 inches from power supplies and 1-kW RF 
amplifiers) whenever the ac power is turned on. The old custom of 
leaning over a linear amplifier on a cold winter night to keep 
warm may not be the best idea!

Table 3 

Typical 60-Hz Magnetic Fields Near Amateur Radio Equipment and 
AC-Powered Household Appliances

Values are in milligauss.

Item                      Field      Distance

Electric blanket         30-  90     Surface Microwave oven           
                         10- 100     Surface
                          1-  10     12" 
IBM personal computer     5-  10     Atop monitor
                          0-   1     15" from screen 
Electric drill          500-2000     At handle 
Hair dryer              200-2000     At handle 
HF transceiver           10- 100     Atop cabinet
                          1-   5     15" from front 
1-kW RF amplifier        80-1000     Atop cabinet
                          1-  25     15" from front

(Source: measurements made by members of the ARRL Bio Effects 
Committee)

There are currently no national standards for exposure to low-
frequency fields. However, epidemiological evidence suggests that 
when the general level of 60-Hz fields exceeds 2 milligauss, 
there is an increased cancer risk in both domestic environments 
(Savitz et al, 1988) and industrial environments (Matanoski et 
al, 1989; Davis and Milham, 1990; Garland et al, 1990). Typical 
home environments (not close to appliances or power lines) are in 
the range of 0.1-0.5 milligauss.

DETERMINING RF POWER DENSITY     

Unfortunately, determining the power density of the RF fields 
generated by an amateur station is not as simple as measuring 
low-frequency magnetic fields. Although sophisticated instruments 
can be used to measure RF power densities quite accurately, they 
are costly and require frequent recalibration. Most amateurs 
don't have access to such equipment, and the inexpensive field-
strength meters that we do have are not suitable for measuring RF 
power density. The best we can usually do is to estimate our own 
RF power density based on measurements made by others or, given 
sufficient computer programming skills, use computer modeling 
techniques.

Table 4 shows a sampling of measurements made at Amateur Radio 
stations by the Federal Communications Commission and the 
Environmental Protection Agency in 1990. As this table indicates, 
a good antenna well removed from inhabited areas poses no hazard 
under any of the various exposure guidelines. However, the 
FCC/EPA survey also indicates that amateurs must be careful about 
using indoor or attic-mounted antennas, mobile antennas, low 
directional arrays, or any other antenna that is close to 
inhabited areas, especially when moderate to high power is used.

Table 4 

Typical RF Field Strengths near Amateur Radio Antennas

A sampling of values as measured by the Federal Communications 
Commission and Environmental Protection Agency, 1990.

                     Freq,    Power,    E Field, Antenna Type         
MHz      Watts     V/m      Location

Dipole in attic       14.15    100     7-100     In home 
Discone in attic     146.5     250    10- 27     In home 
Half sloper           21.15   1000        50     1 m from base 
Dipole at 7-13 ft      7.14    120     8-150     1-2 m from earth 
Vertical               3.8     800       180     0.5 m from base 
5-element Yagi at 60' 21.2    1000    10- 20     In shack
                                          14     12 m from base 
3-element Yagi at 25' 28.5     425     8- 12     12 m from base 
Inverted V at 22-46'   7.23   1400     5- 27     Below antenna 
Vertical on roof      14.11    140     6-  9     In house
                                      35-100     At antenna tuner 
Whip on auto roof    146.5     100    22- 75     2 m from antenna
                                      15- 30     In vehicle
                                          90     Rear seat 
5-element Yagi at 20' 50.1     500    37- 50     10 m from antenna

Ideally, before using any antenna that is in close proximity to 
an inhabited area, you should measure the RF power density. If 
that is not feasible, the next best option is make the 
installation as safe as possible by observing the safety 
suggestions listed in Table 5.

It is also possible, of course, to calculate the probable power 
density near an antenna using simple equations. However, such 
calculations have many pitfalls. For one, most of the situations 
in which the power density would be high enough to be of concern 
are in the near field--an area roughly bounded by several 
wavelengths of the antenna. In the near field, ground 
interactions and other variables produce power densities that 
cannot be determined by simple arithmetic.

Computer antenna-modeling programs such as MININEC or other codes 
derived from NEC (Numerical Electromagnetics Code) are suitable 
for estimating RF magnetic and electric fields around amateur 
antenna systems. And yet, these too have limitations. Ground 
interactions must be considered in estimating near-field power 
densities. Also, computer modeling is not sophisticated enough to 
predict "hot spots" in the near field--places where the field 
intensity may be far higher than would be expected.

Intensely elevated but localized fields often can be detected by 
professional measuring instruments. These "hot spots" are often 
found near wiring in the shack and metal objects such as antenna 
masts or equipment cabinets. But even with the best 
instrumentation, these measurements may also be misleading in the 
near field.

One need not make precise measurements or model the exact antenna 
system, however, to develop some idea of the relative fields 
around an antenna. Computer modeling using close approximations 
of the geometry and power input of the antenna will generally 
suffice. Those who are familiar with MININEC can estimate their 
power densities by computer modeling, and those with access to 
professional power-density meters can make useful measurements.

While our primary concern is ordinarily the intensity of the 
signal radiated by an antenna, we should also remember that there 
are other potential energy sources to be considered. You can also 
be exposed to RF radiation directly from a power amplifier if it 
is operated without proper shielding. Transmission lines may also 
radiate a significant amount of energy under some conditions.

SOME FURTHER RF EXPOSURE SUGGESTIONS     

Potential exposure situations should be taken seriously. Based on 
the FCC/EPA measurements and other data, the "RF awareness" 
guidelines of Table 5 were developed by the ARRL Bio Effects 
Committee. A longer version of these guidelines appeared in a QST 
article by Ivan Shulman, MD, WC2S (see bibliography).

QST carries information regarding the latest developments for RF 
safety precautions and regulations at the local and federal 
levels. You can find additional information about the biological 
effects of RF radiation in the publications listed in the 
bibliography.

Table 5 

RF Awareness Guidelines

These guidelines were developed by the ARRL Bio Effects 
Committee, based on the FCC/EPA measurements of Table 4 and other 
data. 

o Although antennas on towers (well away from people) pose no 
exposure problem, make certain that the RF radiation is confined 
to the antenna radiating elements themselves. Provide a single, 
good station ground (earth), and eliminate radiation from 
transmission lines. Use good coaxial cable, not open wire lines 
or end-fed antennas that come directly into the transmitter area. 

o No person should ever be near any transmitting antenna while it 
is in use. This is especially true for mobile or ground-mounted 
vertical antennas. Avoid transmitting with more than 25 watts in 
a VHF mobile installation unless it is possible to first measure 
the RF fields inside the vehicle. At the 1-kilowatt level, both 
HF and VHF directional antennas should be at least 35 feet above 
inhabited areas. Avoid using indoor and attic-mounted antennas if 
at all possible. 

o Don't operate RF power amplifiers with the covers removed, 
especially at VHF/UHF. 

o In the UHF/SHF region, never look into the open end of an 
activated length of waveguide or point it toward anyone. Never 
point a high-gain, narrow-beamwidth antenna (a paraboloid, for 
instance) toward people. Use caution in aiming an EME 
(moonbounce) array toward the horizon; EME arrays may deliver an 
effective radiated power of 250,000 watts or more. 

o With handheld transceivers, keep the antenna away from your 
head and use the lowest power possible to maintain 
communications. Use a separate microphone and hold the rig as far 
away from you as possible. 

o Don't work on antennas that have RF power applied. 

o Don't stand or sit close to a power supply or linear amplifier 
when the ac power is turned on. Stay at least 24 inches away from 
power transformers, electrical fans and other sources of high-
level 60-Hz magnetic fields.

BIBLIOGRAPHY     

Source material and more extended discussion of topics covered in 
this chapter can be found in the references given below and in 
the textbooks listed at the end of Chapter 2.

W. R. Adey, "Tissue Interactions with Nonionizing Electromagnetic 
Fields," Physiology Review, 1981; 61:435-514.

W. R. Adey, "Cell Membranes: The Electromagnetic Environment and 
Cancer Promotion," Neurochemical Research, 1988; 13:671-677.

W. R. Adey, "Electromagnetic Fields, Cell Membrane Amplification, 
and Cancer Promotion," in B. W. Wilson, R. G. Stevens, and 

L. E. Anderson, Extremely Low Frequency Electromagnetic Fields: 
The Question of Cancer (Columbus, OH: Batelle Press, 1989), pp 
211-249.

W. R. Adey, "Electromagnetic Fields and the Essence of Living 
Systems," Plenary Lecture, 23rd General Assembly, Internat'l 
Union of Radio Sciences (URSI), Prague, 1990; in J. Bach 
Andersen, Ed., Modern Radio Science (Oxford: Oxford Univ Press), 
pp 1-36.

Q. Balzano, O. Garay and K. Siwiak, "The Near Field of Dipole 
Antennas, Part I: Theory," IEEE Transactions on Vehicular 
Technology (VT) 30, p 161, Nov 1981. Also "Part II; Experimental 
Results," same issue, p 175. 

D. F. Cleveland and T. W. Athey, "Specific Absorption Rate (SAR) 
in Models of the Human Head Exposed to Hand-Held UHF Portable 
Radios," Bioelectromagnetics, 1989; 10:173-186.

D. F. Cleveland, E. D. Mantiply and T. L. West, "Measurements of 
Environmental Electromagnetic Fields Created by Amateur Radio 
Stations," presented at the 13th annual meeting of the 
Bioelectromagnetics Society, Salt Lake City, Utah, Jun 1991.

R. L. Davis and S. Milham, "Altered Immune Status in Aluminum 
Reduction Plant Workers," American J Industrial Medicine, 1990; 
131:763-769.

F. C. Garland et al, "Incidence of Leukemia in Occupations with 
Potential Electromagnetic Field Exposure in United States Navy 
Personnel," American J Epidemiology, 1990; 132:293-303.

A. W. Guy and C. K. Chou, "Thermographic Determination of SAR in 
Human Models Exposed to UHF Mobile Antenna Fields," Paper F-6, 
Third Annual Conference, Bioelectromagnetics Society, Washington, 
DC, Aug 9-12, 1981. 

C. C. Johnson and M. R. Spitz, "Childhood Nervous System Tumours: 
An Assessment of Risk Associated with Paternal Occupations 
Involving Use, Repair or Manufacture of Electrical and Electronic 
Equipment," Internat'l J Epidemiology, 1989; 18:756-762.

D. L. Lambdin, "An Investigation of Energy Densities in the 
Vicinity of Vehicles with Mobile Communications Equipment and 
Near a Hand-Held Walkie Talkie," EPA Report ORP/EAD 79-2, Mar, 
1979. 

D. B. Lyle, P. Schechter, W. R. Adey and R. L. Lundak, 
"Suppression of T-Lymphocyte Cytotoxicity Following Exposure to 
Sinusoidally Amplitude Modulated Fields," Bioelectromagnetics, 
1983; 4:281-292.

G. M. Matanoski et al, "Cancer Incidence in New York Telephone 
Workers," Proc Annual Review, Research on Biological Effects of 
50/60 Hz Fields, U.S. Dept of Energy, Office of Energy Storage 
and Distribution, Portland, OR, 1989.

S. Milham, "Mortality from Leukemia in Workers Exposed to 
Electromagnetic Fields," New England J Medicine, 1982; 307:249.

S. Milham, "Increased Mortality in Amateur Radio Operators due to 
Lymphatic and Hematopoietic Malignancies," American J 
Epidemiology, 1988; 127:50-54.

W. W. Mumford, "Heat Stress Due to RF Radiation," Proc IEEE, 57, 
1969, pp 171-178. 

S. Preston-Martin et al, "Risk Factors for Gliomas and 
Meningiomas in Males in Los Angeles County," Cancer Research, 
1989; 49:6137-6143.

D. A. Savitz et al, "Case-Control Study of Childhood Cancer and 
Exposure to 60-Hz Magnetic Fields, American J Epidemiology, 1988; 
128:21-38.

D. A. Savitz et al, "Magnetic Field Exposure from Electric 
Appliances and Childhood Cancer," American J Epidemiology, 1990; 
131:763-773.

I. Shulman, "Is Amateur Radio Hazardous to Our Health?" QST, Oct 
1989, pp 31-34.

R. J. Spiegel, "The Thermal Response of a Human in the Near-Zone 
of a Resonant Thin-Wire Antenna," IEEE Transactions on Microwave 
Theory and Technology (MTT) 30(2), pp 177-185, Feb 1982.

T. L. Thomas et al, "Brain Tumor Mortality Risk among Men with 
Electrical and Electronic Jobs: A Case-Controlled Study," J 
National Cancer Inst, 1987; 79:223-237.

N. Wertheimer and E. Leeper, "Electrical Wiring Configurations 
and Childhood Cancer," American J Epidemiology, 1979; 109:273-
284. 

N. Wertheimer and E. Leeper, "Adult Cancer Related to Electrical 
Wires Near the Home," Internat'l J Epidemiology, 1982; 11:345-
355.

"Safety Levels with Respect to Human Exposure to Radio Frequency 
Electromagnetic Fields (300 kHz to 100 GHz)," ANSI C95.1-1991 
(New York: IEEE American National Standards Institute, 1990 
draft).

"Biological Effects and Exposure Criteria for Radiofrequency 
Electromagnetic Fields," NCRP Report No 86 (Bethesda, MD: 
National Council on Radiation Protection and Measurements, 1986).

US Congress, Office of Technology Assessment, "Biological Effects 
of Power Frequency Electric and Magnetic Fields--Background 
Paper," OTA-BP-E-53 (Washington, DC: US Government Printing 
Office), 1989.

>

-----
Ed Hare, KA1CV                  ehare@arrl.org
American Radio Relay League
225 Main St.
Newington, CT  06111            You will never put the puzzle together  
(203) 666-1541 - voice          if you keep putting all the pieces
ARRL Laboratory Supervisor      back in the box.
RFI, xmtr and rcvr testing  
-----
Newsgroups: rec.radio.amateur.misc