&EPA
United States
Environmental Protection
Agency
Radiation And Indoor Air
Radiation Studies Division
(6603J)
402-R-92-009
December 1992
Questions And Answers
About Electric And Magnetic
Fields (EMFs)
C,ica3o, IL
-------
QUESTIONS AND ANSWERS ABOUT
ELECTRIC and MAGNETIC FIELDS (EMFs)
L INTRODUCTION 1
I. BACKGROUND 2
1.1. What are EMFs? 2
L2. What are the sources of EMFs? 2
1.3. Are EMFs like X-rays? 2
1.4. What can EMFs do to me? 2
L5. How do I reduce my exposure? 3
1.6. What is a gauss? 3
1.7. What is a safe level? 3
1.8. Is it true that levels below 2 milligauss (mG) are safe? Is there a standard? 4
1.9. What is a safe distance from a magnetic field source? 4
1.10. Why isn't the federal government setting a standard for EMF levels? Why have
some states set standards? 4
1.11. Are there natural sources of EMFs? Are they like the fields created by power lines?
Can these cause health effects? . 4
H. MEASUREMENTS 5
n.l. Do I need to get EMF measurements? 5
H.2. What will EMF measurements tell me? 5
H.3. How do I get my house or school measured? 5
n.4. Does EPA recommend measurement contractors? 5
n.5. Can I trust the measurements made by the utility? . . • 5
n.6. My neighbors had EMFs around their house measured. Is my house the same? 5
n.7. Can I make my own EMF measurements? 6
n.8. - Where can I buy or rent a meter? 6
n.9. Does EPA recommend meters? 6
n.10. How much do meters cost? Which one is the simplest or best? 6
n.ll. How can I get instructions on how to make these measurements? 7
n.12. How do I know how my readings compare to others? „. . . 7
nLHEALTH 8
HI.1. What can EMFs do to me? 8
m.2. What are cancer clusters? 9
m.3. There are a lot of sick people in my neighborhood. There is [some source] here.
Could that be the reason? 9
m.4. Who should we contact when we suspect a cluster? 10
m.5. I can percieve electric and magnetic fields, what can I do? 11
m.6. I'm pregnant. Will EMFs (or specific source) hurt me or my baby? 11
m.7. The EPA report is just about cancer, but I've heard there are other effects. What are
they? Why hasn't EPA looked into those effects? 12
IV. SCHOOLS 12
i December 1992
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IV. 1. They've taken measurements in my child's school. I know what the measurements
' are, but what do they mean? 12
IV.2. The measurements were higher in some areas (playgrounds, classrooms, etc.).
Shouldn't the kids be prevented from entering those areas? 13
IV.3. How do we get our school measured? 13
IV.4. I heard that a nearby school had its schoolyard measured. I know the values. Is my
schoolyard the same? ? 13
IV.5. Our children use VDTs at school. Is that safe? ....'. 13
IV.6. Can't the computer be set up to minimize exposure? 13
IV.7. Can you tell me about low emission VDTs and screens that are supposed to block
EMFs? We were thinking about buying that sort of equipment for our school if it
works 14
IV.8. Besides power lines, substations, and VDTs, what are other common sources of
EMFs in schools? 14
V. TRANSFORMERS 14
V.I. What are transformers? 14
V.2. What is that metal electrical box on the comer of my lot IS
V.3. Do EMFs come from transformers? 15
V.4. Aren't there chemicals in the transformers? 15
V.5. Are transformers safe? 15
VL REAL ESTATE .15
VI. 1. What are the regulations about EMFs that pertain to houses and real estate
transactions? 15
VI.2. What do I tell people about the power lines behind my house? 15
VI.3. Should I buy/rent a house near a power line or substation? 15
VI.4. If I am buying a house, can I get the seller to test for EMFs? 16
VH. MITIGATION . 16
Vn.l. How can I stop the fields from coming into my house? Can't I shield them? 16
vn.2. I commute on the subway/train - are there fields there? Is it safe? 16
VH.3. I've heard about "Prudent Avoidance." What is that? How can I apply it to my
life? 16
VH.4. How can I avoid EMFs? 17
Vn.5. What can be done to assure that new transmission/distribution lines have low fields?
Can fields be completely eliminate? 17
vn.6. What can be done to reduce fields from existing transmission/distribution lines?
. - - Can fields be completely eliminated? 17
Vn.7. What can be done to reduce or eliminate exposure hi homes? 17
Vn.8. What are utilities/manufacturers doing about reducing EMF exposure? 17
VDTs PLUS THE OFFICE ENVIRONMENT . 17
VQI.1. I am concerned about EMFs and my VDT. What is the bottom line? 17
Vm.2. What can you tell me about low emission VDTs and screens that are
supposed to block EMFs? 18
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Vm.3. I read an ad that said this company's VDTs were safe and certified by EPA
to have little/no EMFs. Is that true? 18
Vm.4. Who else can I talk to about different VDTs and claims about low fields and
"safe" monitors? '. 18
Vm.5. How do I contact the FDA, NIOSH, or OSHA? 18
Vm.6. Are VDTs different than my television? 19
Vm.7. „ How far should I sit from my VDT? What about from other people's VDTs? . . 19
Vm.8. Why doesn't the U.S. have VDT standards like Sweden? 19
Vm.9. I've heard that laptops are safe. Is this true? 19
VTH.10. Is there someone who can come to our office to measure EMFs? 19
Vm.ll. What are other common sources of EMFs in the office? 20
DC. RESEARCH 20
K.l. Isn't all research being done by the utilities? 20
K.2. Isn't that (utility) work biased? 20
DC.3. What research is underway now? 20
DC.4. Why isn't the federal government doing more research? 20
DCS. Why is the federal government so slow in responding? . 20
X. STANDARDS AND REGULATIONS 20
X.I. Can the federal government make the power company move/change the
transmission/distribution lines? 21
X.2. Can the federal government stop the power company from putting in that new line
or increasing the voltage? 21
X.3. What is a right-of-way (ROW)? 21
X.4. Measurements at the edge of the ROW are higher than state rules. What should I do
to make the power company fix this? 21
X.S. Why have some states written or proposed standards for EMFs? 21
X.6. Why hasn't the federal government regulated EMFs? 21
December 1992
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INTRODUCTION
The purpose of this document is to help EPA staff
better understand and respond to questions from
the public about electric and magnetic fields, also
known as EMFs. Scientific understanding of the
potential health risks from EMF exposure is in an
early stage. Because the science is complicated
and the health issue unresolved, it is critical that
we carefully explain what we know and don't
know and not give contradictory messages. We
want to provide information that is consistent and
scientifically correct.
This document lists commonly asked questions and
suggested answers by topical area. The questions
and answers are given in a somewhat casual style
to simulate a telephone conversation. Some of the
questions anticipate issues that will arise in the
course of a conversation. The questions and
answers were derived from the experience of EPA
staff, both at Headquarters and in the Regions,
who routinely field inquiries from the public on
EMFs. We do not expect that the answers will be
given verbatim. Answers must be tailored to
respond to the specific questions and needs of the
caller. The reader may find that some of the •
answers seem repetitious. Repetition and
reinforcement are here by design. The document
is designed so that the user can start at any topic
of interest to callers without always having to refer
to background or related information in other
sections. For example, some callers are only
interested in video display terminals (VDTs) at
work. Some are interested in schools, including
VDTs at schools. To meet both needs, some
questions and answers on VDTs are repeated.
Most questions about EMFs concern sources and
uses of electricity, namely 60 Hz power. The
questions and answers in this booklet focus on 60
Hz exposures rather than exposures from sources
transmitting higher frequencies.
Certain basic ideas should be understood and
transmitted when responding to the public. The
first item on this list is a quote from the EPA
Science Advisory Board review of the EPA
document "Evaluation of the Potential
Carcinogenicity of Electromagnetic Fields"
1) "Some epidemiological evidence is suggestive of
an association between surrogate measurements of
magnetic field exposure and certain cancer
outcomes. In such studies, the existence of
confounders is always a- possibility, but since no
common confounder has yet been identified, the
existing evidence can not be dismissed. In the
absence of much better exposure information and an
understanding of which exposures are significant, no
precise exposure-response relationship has yet been
adduced. This lack, together with limited
understanding of possible biological mechanisms,
prevents the inference of cancer causality from these
associations at this time." In other words, there is
some evidence that points to a relationship between
EMFs and some types of cancer. Though the body
of evidence can not be dismissed, it is not complete
enough to draw meaningful conclusions.
2) Other health effects have not been studied as
extensively as cancer so any possible relationship
with EMF exposure is even more uncertain than the
cancer issue.
3) Although the public tends to focus on exposure
from transmission lines, for most people exposure
to magnetic fields comes more from sources such as
appliances and household wiring.
4) Research is being sponsored and conducted by
. both government organizations and the electrical
power and products industry. A combined
government and industry research effort is planned
for 1993.
December 1992
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BACKGROUND
L4. What can EMFs do to me?
LI. What are EMFs?
"EMFs* is a shorthand term for "electric and
magnetic fields" or "electromagnetic fields."
Electric and magnetic fields may occur alone or in
combination and are a form of non-ionizing
radiation. Examples of non-ionizing radiation
include microwaves, visible light, and some
ultraviolet radiation. The American electric power
system operates at 60 hertz (Hz). This means mat
the electric charges (current) flowing in the system
changes direction 60 times a second. Although
electric and magnetic fields from 60 Hz exposures
are not considered "radiation" for various frdmfcai
reasons, they are still called "non-ionizing
radiation".
L2. What are the sources of EMFs?
Electric fields are produced by the presence of
electrical charges, and magnetic fields are
produced by the movement of those charges.
Electricity flowing in a wire or being used in an
appliance creates electric and magnetic fields. All
power lines and electrical appliances that draw
current have electric and magnetic fields around
them.
13. Are EMFs like X-rays?
No. X-rays, microwaves and other radio waves,
and the electric and magnetic fields from power
fines and and electrically powered appliances are
all part of the electromagnetic spectrum. But
X-rays are a form of electromagnetic radiation
with high levels of energy. This energy is
sufficient to dislodge electrons from atoms that the
x-ray strikes; a process called ionization which can
result in cancer. EMFs, microwaves and other
similar types of electric and magnetic fields do not
ionize atoms because of their lower energy levels.
There are many unanswered questions raised by the
research done so far. There have been both positive
and negative studies. We are not sure if EMF
exposure adversely affects human health. More
careful and extensive study of EMFs is needed.
Since 1979, some studies of human populations,
called epidemiology studies, suggest a potential
relationship between exposure to EMFs and certain
cancers. Unfortunately, there are many
uncertainties surrounding this information. For
example, most of the epidemiological studies have
very limited information on what types of exposure
were experienced by the people in the studies. The
observed increase in cancer was more pronounced
for what are called "surrogates" or "indirect"
estimates of EMF exposure than for electric and
magnetic fields measured using meters. You may
have heard about "wiring codes." Coding or
characterizing houses according to the types of
nearby power lines has been one method to estimate
EMF exposure in these studies. This is a
"surrogate" of exposure.
The fact that disease incidence is correlated with
surrogate indexes for magnetic field exposure but
not with direct measurements, could be explained in
each of three ways or combination of these ways: a)
the fields were different in the past, during the onset
of disease; than those measured later during the
study; b) the wrong component or attribute of the
fields was measured; and/or c) some other crucial
factor may be present which is unknowingly .part of
what is being defined by the surrogate measure of
exposure. That factor could be some feature of the
EMF exposure or something else altogether, such as
a chemical exposure or differences in lifestyle.
Some laboratory studies have shown that extremely
low frequency (ELF) electric and magnetic fields
can affect various activities of cells. The laboratory
studies on biological effects also are uncertain. For
example, many of the positive results have only
been found in one laboratory. Usually, before a
December 1992
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result is accepted as proof by scientists, it has been
seen by several different investigators.
Additionally, it is not clear whether some of the
biological effects seen in laboratory studies of cells
would be harmful effects if they also occurred in
people or whether They are minor changes that our
bodies could adjust to.
Hie bottom line is that there is no established
cause and effect relationship between EMF
exposure and cancer or other disease. For this
reason, we can't define a hazardous level of EMF
exposure.
It is known that one type of magnetic field can
have beneficial health effects. One treatment used
by doctors to help heal broken bones that are not
healing normally, is to expose the area for a few
minutes a day to a specific type of magnetic field.
This apparently affects the body's capability for
healing bone.
1.5. How do I reduce my exposure?
While electric fields can be easily shielded,
magnetic fields are much more difficult to shield.
Electric fields are shielded to some degree by
almost everything such as trees, bushes, walls, and
so forth. Magnetic fields can be reduced by
enclosing the source in certain types of metal such
as something called Mu metal which is a special
alloy. The fields are still present, but the metal
has the capability to contain them. This approach
to reducing field levels is not practical for many
sources, including power lines. (Some gadgets
have recently appeared on the market, such as
buttons, pens, etc., claiming to shield one from
fields; it is almost certain that these do not work.)
Magnetic field intensity can also be reduced by
placing wires close together so that the field from
one wire cancels the field from the other. This is
now being done in new designs for electric
blankets. To some degree the same thing can be
done for power lines, but for safety and reliability
reasons power lines have minimum required
spacing.
Because of the way appliances are made, they have
the potential to have very high localized fields, but
then the fields decrease rapidly with distance. For
example, typical magnetic field strengths not near
an appliance are 0.1 to 4 milligauss (mG), but the
field from an electric can opener can be 20,000 mG
at 3 centimeters (approximately 1 inch) from the
appliance. At 30 centimeters (approximately 1
foot), appliance fields are usually around 1000 times
lower. For the can opener mentioned above, the
level would probably be around 20 milligauss.
When you stand under a power line, you are already
at least 20 feet or more away from the line,
depending on its height above ground. Under a
typical 230 kilovolt transmission line the magnetic
field is probably less than 120 milligauss. In
contrast, if you move about 100 feet away from the
line, the magnetic field is probably about 15
milligauss, and if you are 300 feet away from the
line, the magnetic field is probably less than 2
milligauss.
From these examples, we can see that distance
from the source of the magnetic or electric field can
substantially reduce exposure.
1.6. What is a gauss?
The gauss is a unit for the strength of a magnetic
field, also known as magnetic flux density. A
related unit used internationally for magnetic flux
density is the tesla. One tesla is equal to 10,000
gauss. Magnetic flux density is measured in terms
of lines of force per unit area. Remember the
patterns that were generated by iron filings on a
piece of paper which was placed over a magnet?
These patterns are field lines. We normally speak
of magnetic fields in terms of thousandths of a
gauss or milligauss, abbreviated "mG."
L7. What is a safe level?
We don't know if EMF exposure is harmful (aside
from the concern for electric shocks and burns for
extreme exposure). We don't know if certain levels
of EMFs are safer or less safe than other levels.
December 1992
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With most chemicals, we assume exposure at
higher levels is worse than less exposure at lower
levels. This may or may not be tnie for EMFs
also. More research is required to identify dose-
response relationships. There is some evidence
from laboratory studies mat suggests that there
may be "windows" for effects. That means mat
biological effects are observed at some frequencies
and intensities but not at others. Also, we do not
know if continuous exposure to a given field
intensity causes a biological effect, or if repeatedly
entering and exiting of the field causes effects.
There is no number to which we can point and say
"That is a safe or hazardous level of EMF
exposure."
L8. Is it true that levels below 2 mffligauss
(mG) are safe? Is there a standard?
We do not yet know what if any magnetic field
levels are safe or unsafe. The level of 2 mG is an
arbitrary value used in some epidemiological
studies to place people in broad exposure
categories. Some other level could have been
used. But, because no dose/response relationship
has yet been determined for EMFs, we cannot
establish a level which would be considered safe
or unsafe.
As a result, neither the EPA nor any other federal
regulatory agency has established a standard for
EMFs.
1.9. What is a safe distance from a magnetic
field source?
Since we do not know if EMF exposure is
harmful, we don't know what intensity of field is
safe or unsafe. In turn, we cannot say what is a
safe distance. A related question is, "At what
distance is the strength of the field indiscernible
from the background field levels?" It depends on
the source of the magnetic field and the what the
background field level is. Background magnetic
fields usually range from 0.1 to 4.0 illigauss
(mG). In the case of most high voltage power
lines, at 300 feet from the center span, the
magnetic field has usually dropped below 2 mG. In
the case of an electric can opener, the magnetic
field is probably below 2 mG approximately 3 feet
away.
L10. Why isn't the federal government setting a
standard for EMF levels? Why have some
states set standards?
Several states have established standards for electric
and/or magnetic fields at the edge of the right of
way for power lines, usually transmission lines.
These standards either have been on the books for a
while, and are based on older scientific information,
or were set more recently to establish levels of
exposure that should not be exceeded. The .
standards were intended to keep field levels from
going any higher, because of the existing
uncertainty about health risks.
1.11. - Are there natural sources of EMFs? Are
they like the fields created by power lines?
Can these cause health effects?
Yes, there are natural sources. The earth has a
magnetic field that is approximately 500 milligauss.
The earth's magnetic field is relatively constant,
meaning that it does not change very much with
time, unlike power lines. There are electromagnetic
fields associated with thunderstorms. Lightning is a
source of EMFs. Some animals like sense natural
electric and magnetic fields. Our bodies also
produce electrical fields that make our nervous
systems and hearts work. These internal electric
fields are fairly high.
Batteries and some electrical systems also have
fields that do not change with time; these are called
static or DC fields. DC stands for direct current
In contrasts, fields from most electrical power
systems and appliances vary in time and so are
called time-varying fields or AC fields. AC stands
for alternating current. Electric power systems in
the United States operate at 60 Hz which cycles 60
times per second.
December 1992
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IL MEASUREMENTS
ILL Do I need to get EMF measurements?
That's up to you. EPA neither recommends nor
discourages people from obtaining field
measurements. You may decide to have EMF
measurements made if you want to satisfy personal
questions, concerns, or curiosity about EMF
exposures.
n.2. What will EMF measurements tell me?
Magnetic and electric field measurements will not
tell you whether or not your exposure is harmful
or puts you at an increased risk, but they may
allow you to tell how your home compares to the
"average" home. You should be aware that the
meters typically used for home measurements can
only tell you "average field strength" in milligauss
units, at the time the measurements are performed.
Even these measurements will vary over time
based on many factors, such as which appliances
are being used. EMF laboratory studies show that
biological effects may depend on one or more of
many aspects of exposure like frequency, intensity,
orientation of the field, duration, transient or
intermittent current, and voltage spikes. Scientists
still do not know what aspects of exposure, if any,
are important. We therefore have no way of
establishing either a safe or unsafe level. On the
basis of available scientific data, there is no way
of interpreting the health significance of EMF
measurements.
IL3. How do I get my house or school
measured?
Depending on where you live, your local power
company may offer to conduct field measurements
around your home. Additionally, your state
Health Department or State Department of
Environmental Protection may also be able to
provide you with field measurements or refer you
to consulting firms that conduct electric and
magnetic field measurements. Consulting firms
may also be found through advertisements in
environmental and computer magazines. These
firms will perform EMF measurements usually for
$200 - $300. Alternatively, you can buy your own
meter for $75 and up. These meters usually come
with instructions.
n.4. Does EPA recommend measurement
contractors?
No. EPA does not recommend or endorse private
companies and contractors. EPA does not have a
proficiency program - like the one for radon testing
firms - to measure the qualifications of contractors
who conduct electric and magnetic field
measurements. Therefore, we cannot endorse or
comment on the qualifications of any contractor.
The state of California is developing a list of firms
making EMF measurements. But the state is not
recommending or certifying these firms. To obtain
the list when it is completed, call (415) 540-2669 or
write to the Special Epidemiology Studies Program,
California Department of Health Services, 2151
Berkeley Way, Room 704, Berkeley, CA 94704.
IL5. Can I trust the measurements made by the
utility?
Yes. Utilities should have the expertise and proper
equipment to make accurate measurements. There
is no reason to believe that the utility is trying to
mislead you by providing you with false readings.
Since we do not understand very much about the
possible health effects of EMFs or what levels, if
any, might be hazardous, there is no reason for the
utility to give you false results. It is important to
remember that readings will vary depending on
factors such as the time of day the measurements
were taken. The differences in readings usually
reflect how much electricity is being used by the
power system and other things, like what appliance
are being used.
H.6. My neighbors had EMFs around then*
house measured. Is my house the same?
Probably not. Measurements in the house are often
affected by many sources of magnetic fields
December 1992
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including electrical appliances or power system
components (transmission or distribution lines,
transformers, or house wiring). Fields are even
produced by "ground currents" flowing in water
pipes. EMFs decreases quickly with distance from
the source. A power line or other source close to
your neighbor's house may generate a measurable
field there but levels at your house may be very
different
EMFs can also be generated by many sources in
addition to power lines such as small appliances,
hot water heaters, auxiliary power generators, and
household wiring. Since the presence of various
kinds of appliances varies from house to house, so
do EMF levels. Therefore, EMF levels in your
neighbor's house may be very different from those
in your own house.
H.7. Can I make my own EMF
measurements?
Yes, but be sure to learn how to make
measurements properly. Before using any
instruments, you should educate yourself on the
use and degree of sensitivity, accuracy, and proper
operation of the meter. This information can be
provided by the manufacturer. You could also
follow recommendations from trade associations
on how to measure fields. Table 1 includes some
sources of measurement protocols.
Most simple magnetic field meters only read
average field intensity, given in milligauss (mG).
Measurements can vary with time, space, and
power load on the electrical system. Some meters
only measure magnetic fields. Some meters
measure both electric and magnetic fields.
Remember, even if you or someone else makes the
measurements properly, there is no basis for
judging the meaning of the data, relative to
possible health effects.
H.8. Where can I buy or rent a meter?
Advertisements for companies that sell or rent
meters can be found in environmental or computer
magazines. Similar advertisements can also be
found in scientific equipment journals, as well as
newsletters such as Microwave News. EMF Health
and Safety Digest and journals such as IHHH
Spectrum.
Microwave News also ptaintains a directory of
companies which sell or rent magnetic field meters.
We can send you a copy of that list, or you may
obtain a copy of mis directory by sending a letter
requesting the "Gaussmeter Table" and a self-
addressed stamped envelope and $1.00 for shipping
and handling to:
Microwave News
P.O. Box 1799
Grand Central Station
New York, NY 10163
IL9. Does EPA recommend meters?
EPA does not recommend any specific supplier,
manufacturer, or type of measurement equipment.
n.10. How much do meters cost? Which one is
the simplest or best?
Prices for meters range between $75 and $650.
Companies may rent meters for between $60 and
$100 per week. Electric and magnetic fields are
three dimensional. Each dimension is called an
"axis" (the plural is "axes"). To properly measure
a magnetic field all three axes of the field should be
measured— horizontal (front), horizontal (side) and
vertical. "Single-axis" meters measure only one
axis at a time and must be rotated until it is aligned
with the field. A three-axis meter can get an
accurate measurement no matter how it is oriented
in the field, and they measure all three axes at the
same time. Single-axis meters are generally the
cheapest; while three-axis meters which display an
integrated measurement (all three axes) are more
expensive.
The less interpretation needed, the simpler an
instrument is to use, and readings are less subject to
error. Therefore, meters displaying an integrated
measurement of an three axes together are the
December 1992
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simplest to use. However, these meters tend to be
more expensive, and also have some additional
capabilities that may be hard to team and require a
computer. The single-axis meters are generally
the cheapest, but must be properly oriented.
n.ll. How can I get instructions on how to
make these measurements?
There are protocols (intructions for standardized
measurement procedures) that can tell you how to
perform the measurements. Table 1 is a list of
these protocols, and where they may be obtained.
Additional assistance may be available at
universities with engineering or physics
departments. You may also wish to contact the
manufacturer of the instrument for specific
operating guidance.
H.12. How do I know how my readings
compare to others?
Table 2 shows some typical magnetic field
measurements near transmission lines. Your
utility company can tell you whether the line you
are measuring is a transmission or distribution
line. It is important to remember that
measurements may vary for a variety of reasons
like weather and operating conditions. Typical
residential exposures, away from any appliances,
rage from 0.1 mG to 4 mG.
This sort of information on typical values and
comparative exposures is also given in several
publications such as those available from the
Bonneville Power Administration or in the
brochure prepared by Carnegie Mellon University
entitled, Electric and Magnetic Fields from 60
Hertz ^" Powen What do we
Dossible health risks.
TABLE 1
SOURCES OF PROTOCOLS AND METHODS
TO MEASURE ELECTRIC AND MAGNETIC
FIELDS
Electric and Magnetic Fields: Measurements and
Possible Effects on Human Health from
Appliances, Power Lines, and Other Common
Sources. May be obtained from:
Special Epidemiology Studies Program
California Department of Health Services
2151 Berkeley Way, Room 704
Berkeley, CA 94704
(415) 540-2669
IEEE Standard Procedures for Measurement of
Power Frequency Electric and Magnetic Fields
from AC Power Lines. Standard 644-1987.
rRF.F. Measurements of Power Frequency
Magnetic Fields Away from Power Lines. 90 SM
423-4 PWRD.
IEEE Guide for Measurement of DC Electric
Field Strength and Ion Related Quantities.
Report I.D.: SH13805. 1990.
All IHHH protocols may be obtained from:
The Engineering Societies Library
345 E. 47th Street
New York, NY 10017
(212) 705-7611
^
IEC Measurement of Power Frequency Electric
Fields. International Electrotechnical
Commission (IEC), Document 833. 1987.
May be obtained from:
American National Standards Institute
1430 Broadway
New York, NY 10018
(212) 354-3300
December 1992
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TABLE 2
MAGNETIC FIELDS NEAR ELECTRIC POWER TRANSMISSION LINES
Types of Transmission Maximum on '• Distance from ifagg
Line Right-of-way 50' " 100' 200' 300' ,
115 Kflorotts (kV) Magnetic Fields in milligauss (mG)
Average usage 30 72
Peak usage 63 14 4
230 KDovofts (kV)
Average usage 58 20 7
Peak usage 118 40 15
500 KfloTohs (kV)
Average usage 87 29 13
Peak usage 183 62 27
0.4 0.2
0.9 0.4
1.8 0.8
3.6 1.6
3.2 1.4
6.7 3.0
Information courtesy of Bonneville Power Administration.
nLHEALTH
ELI. What can EMFs do to me?
There are many unanswered questions raised by
the research done so far. There have been both
positive and negative studies. We are not sure if
EMF exposure adversely affects human health.
More extensive study of EMFs is needed.
Since 1979, some studies of human populations,
called epidemiology studies, suggest a potential
relationship between surrogates for exposure to
EMFs and certain cancers. Unfortunately, there
are many uncertainties surrounding this information.
For example, most of the epidemiological studies
have very limited information on what types of
exposure were experienced by the people in the
studies. The observed increase in cancer was more
strongly associated with what are called
•surrogates" or "indirect" estimates of EMF
exposure than for electric and magnetic fields
measured using meters. You may have heard about
"wiring codes." Coding or characterizing houses
according to the types of nearby power lines has
been one method to estimate EMF exposure in these
studies. This is a "surrogate" of exposure.
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December 1992
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Hie fact that disease incidence is correlated with
surrogate indexes for magnetic field exposure but
not with direct measurements, could be explained
in each of three ways or combination of these
ways: a) the fields in the past, during the onset of
disease, were different than those measured later
during the study; b) the wrong component or
attribute of the fields was measured; and/or c)
some other crucial factor may be present which is
unknowingly part of what is being defined by the
surrogate measure of exposure. That factor could
be some feature of the EMF exposure or
something else altogether, such as a chemical
exposure or differences in lifestyle.
Also, some laboratory studies have shown that
extremely low frequency (ELF) electric and
magnetic fields can affect various activities of
cells. The laboratory studies on biological effects
also are uncertain. For example, many of the
positive results have only been found in one
laboratory. Usually, before a result is accepted by
scientists as proof, it has been seen by several
different investigators. Additionally, it is not clear
whether some of the biological effects seen in
laboratory cellular studies would be harmful
effects if they also occurred in people or whether
they are minor changes that our bodies could
adjust to.
The bottom line is that there is no established
cause and effect relationship between EMF
exposure and cancer or other disease. For this
reason, we can't define a hazardous level of EMF
exposure.
On the other hand, it is known that one type of
magnetic field can have beneficial health effects.
One treatment used by doctors to help heal broken
bones that are not healing normally, is to expose
the area for a few minutes a day to a specific type
of magnetic field. This apparently affects the
body's capability for healing bone.
m.2. What are cancer dusters?
The amount of disease (measured by either rates or
number of cases) in any population or community
naturally fluctuates somewhat over time. If you
look at enough populations or if you look at one
population for a long period of time, you would
expect to see an unusually large (or small) amount
of disease once in a while. If the makeup of the.
community changes, the amount and type of disease
also changes. For example, a community with
mostly older people will have more cases of chronic
diseases such as cancer or heart disease. Yet
sometimes the amount of disease, usually a specific
disease, varies more than might be expected for a
given community. This unusual variation is called a
"cluster."
It is often difficult to evaluate clusters. First, it
must be determined with statistical methods whether
a truly unusual change has occurred or whether this
is only normal fluctuation. Second, the cause of the
change or cluster must be determined. This is the
hard part, especially for chronic diseases. Cancer,
like most diseases, has multiple causes; that is, no
single reason can explain why one person gets
cancer and another does not. It may be relatively
simple to determine the cause of food poisoning
hepatitis, or influenza clusters. But usually
impossible to clearly determine the cause of a
cancer cluster. Suspected EMF cancer clusters are
even more problematic because of the uncertainty of
EMF and cancer connections.
m.3. There are a lot of sick people in my
neighborhood. There is [some source]
here. Could that be the reason?
The following additional questions will often come
up in this sort of a health discussion:
Can we get it measured?
Can you do a study here?
Why hasn't somebody done something?
What are the standards?
What effects are associated with EMFs?
Do EMFs cause this disease or symptoms?
December 1992
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It is important to realize that what seems to be an
unusual excess may not necessarily be a greater
than normal variation in the expected incidence of
health problems. Especially in small
where people are familiar with many of the other
people in the area, one becomes aware of the
many problems that do occur normally. If one
particular kind of disease or health effect occurs
many times in a community, the odds that some
agent is a cause of the disease increases.
However, when the kinds of problems or diseases
vary it becomes less likely that one particular
agent is at work. Trying to weed out the health
cases mat are not common to a particular agent, in
order to actually "see" the cluster, is an important
part of the epidemiologist's job. This becomes
very important and at the same time very difficult
for an agent whose health effects are not well
known and whose effects might vary from person
to person.
EMFs are particularly difficult for epidemiologists.
The problems that have been attributed by some
people to EMFs include several different kinds of
cancer, birth defects, behavioral changes, slowed
reflexes, and spontaneous abortions. Therefore,
the process of deciding which health problems in a
community belong to the "cluster" becomes
exceedingly difficult. So... the answer to the
question, "Can that source be the cause of my
problems?", is "maybe-maybe not". The source
might be the problem but trying to show that it is
can be very difficult if not just impossible. The
health officials have to be good detectives as well
as competent health professionals. Because of the
difficulties, expense and uncertain results, unless
the conditions are right, there is usually not much
value in conducting an epidemiological study.
One way to get measurements taken is to request
that the utilities (in the case of power lines), or the
owner of whatever source is of concern, perform
the measurements. So far most health agencies do
not have the staff, expertise or equipment to
provide that service. Private measuring businesses
are being established to fill this demand but at this
time there is no licensing or quality assurance
available to indicate the qualifications of these
people.
Another problem associated with getting
measurements is that there really is little advice that
can be given when the results are in. The standards
in effect are associated with very high field levels,
so you can be reasonably certain that you won't be
measuring anything near this range.
m.4. Who should we contact when we suspect a
duster?
The first responder to calls of suspected clusters is
the local health department and then state health
agencies. When the state lacks a specific capability,
the state may request assistance from EPA or from
the Centers for Disease Control (CDC). EPA has
provided EMF measurement assistance several times
over the past few years. CDC investigates health
problems and disease outbreaks.
If you suspect that there are too many cases of a
particular disease in your community or if you
suspect that the health of people within your
community is simply not what it should be, contact
your county health agency. They should have
statistics for the local areas and would be able to
discuss local issues. If they determine that a
problem exists and do not have the capability to
respond property, they will in turn request
assistance from the state authorities. While
investigations of clusters and determinations of
clusters are very difficult, the suspected cluster
should always be reported. Often, a closely knit
community will be aware of health concerns before
an agency will. At other times, the agencies that
maintain health registries will note statistical
increases and initiate an investigation.
It is difficult to determine the possible causes of
clusters. People are exposed to many things in their
environment And people have differing lifestyles.
Any one agents might be responsible or many
agents might all be working together to produce
some combined effect which is more significant than
simply the sum of their individual effects.
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December 1992
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m.5. I can percieve electric and magnetic
fields, what can I do?
The following questions will often come up in this
sort of a discussion.
Why is this?
Where is it coming from?
Are mere other people like me?
What can I do?
My doctor can't help. Where else do I go?
Where do I find information?
Can you do something? ...make it stop?
I know its from (source). Can you
make them stop?
Generally, humans appear unable to sense or
detect low levels of EMFs. Some animals have
developed this capability and use it for detecting
and capturing prey and possibly for navigating.
Yet, since these abilities evolved in some animals,
it is possible that biological systems have at least a
very rudimentary ability to respond to such fields
and some people may be more sensitive than
others. Additionally, there are "large" effects that
can be detected, such as static charges making the
fine hairs on the body stand up, dental work acting
as radio receivers, induced body currents which
might be felt (if large enough) and possibly effects
which we have not yet documented. Some people
report that they can "sense" low-level EMFs,
however, this subject has not been studied very
much.
We don't have much advice for people who say
they are sensitive to electric or magnetic fields.
While grounding of sources might alleviate large
static charges and dental work might reduce the
radio effects, too little is known about the actual
field-body interaction to suggest anything further
in terms of mitigation.
DI.6. I'm pregnant. Will EMFs (or specific
source) hurt me or my baby?
This following additional questions will often come
up in this sort of health discussion.
I work at a VDT all day long. Is that safe?
We just moved into a home near power
lines. Will that hurt my unborn child?
I just lost a baby. Could it be because of my
electric blanket (power lines, etc.)?
There are several issues to consider with respect to
concerns about pregnancy and EMF exposure:
1.
2.
3.
Are EMFs harmful? There is insufficient
scientific evidence to establish whether
EMFs are harmful. The EPA recently
reviewed the scientific literature with respect
to any potential cancer effect and concluded
that although some epidemiological studies
have shown an association between cancer
and surrogates of EMF exposure, cause and
effect relationships have not been
established. Laboratory studies have
demonstrated that biological changes within.
cell and tissue cultures can be induced by
EMFs, but these changes have not been
linked to human health effects. EPA has not
formally assessed potential reproductive and
developmental effects. These effects have
not been studied as extensively as cancer.
The few epidemiological studies concerning
reproductive effects have been inconclusive.
I have heard children are more sensitive?
We have no evidence that children are
especially sensitive. Some of the first
studies concerned cancer and children, and
received a great deal of attention. But there
have also been some occupational studies
dealing with adults that also found some
correlations with potential exposure to
EMFs.
more sensitive? We do not have enough
evidence to answer that question. There
have been reports about clusters of
miscarriage and birth defects among VDT
users or from electric blanket exposures.
Some studies have been negative, and some
have been positive. This question has not be
11
December 1992
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studied as extensively as cancer, and so
may be viewed as even more
4. HffW CTP exposures from VDTs and other
devices be reduced?
a) By sitting at arms length from a
terminal or pulling the keyboard back still
further; magnetic fields fall off rapidly with
distance.
b) By switching VDTs off (not the
computer necessarily) when not in use.
c) By spacing and locating terminals in the
workplace, so that work stations are
isolated from the fields from neighboring
VDTs. Fields will penetrate partition
walls, but do fall quickly with distance.
d) By using electric blankets (or water bed
heaters) to warm beds but unplugging them
before sleeping. Magnetic fields disappear
when the electric current is switched off.
However, electric fields may exist as long
as a blanket is plugged in.
e) By not standing close to sources of
EMFs such as microwave ovens while in
use. Standards are in place to limit
microwave emissions, however, the electric
power consumption by a microwave oven
results in magnetic fields that are high close
to the unit. The same is true of other
appliances as welL
m.7. The EPA report is just about cancer, but
I've heard there are other effects. What
are they? Why hasn't EPA looked into
those effects?
Various bioeffects have been attributed to EMFs.
These include behavioral changes in lab animals,
altered circadian rhythms (daily metabolic and
behavioral cycles), altered levels of melatonin
production (a hormone thought to play a role in
cancer inhibition), altered movement of certain
ions across cell membranes and other "biological"
responses.
Also, birth defects, miscarriages, low birth weight,
loss of memory, and slowed reflex responses are
health effects sometimes attributed to EMFs, but
there is not broad scientific support for such
assertions. Cancer is the most extensively studied
health effect, yet no cause and effect relationship
has been established between EMF exposure and
cancer, and no hazardous effect level can be
defined. The potential for other health effect should
be viewed as even more uncertain. EPA has
prepared a report describing the research needed to
reduce the uncertainties in a health risk assessment
of EMF. These research needs address cancer,
reproduction, development, the central nervous
system, and the immune system as well as
biophysical mechanisms, exposure assessment, and
control technology.
IV. SCHOOLS
IV.l. They've taken measurements in my child's
school. I know what the measurements
are, but what do they mean?
The measurements were probably made with a
Gaussmeter which is used to measure magnetic
fields. If so, the measurements represent the
intensity of the magnetic fields in that location.
Magnetic fields are produced by any source that
uses electricity, including components of the electric
power system (power transmission or distribution
lines, transformers, or building wiring) and
electrical and electronic devices. Magnetic fields
are even produced by "ground currents" flowing in
water pipes. The intensity of the magnetic field
depends on the amount of electric current flowing
through the electrical system or device.
While the possibility of a public health concern has
been raised in some epidemiological studies, we do
not yet have enough information to say whether
EMFs pose a health risk or not. These same studies
helped us to understand that we need to learn more
about what aspect of EMF exposure may be most
12
December 1992
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relevant. For example, scientists do not know
whether we should be concerned with the strength
of the field, the rate of change in the field
strength, the electric current induced hi the body,
or other variables or exposures completely
unrelated to electric and magnetic fields. This
makes interpretation of field measurements very
difficult. Although not completely satisfactory,
your measurement results can, however, be
compared to others to see if yours are typical or
not -It must be remembered that no safe or unsafe
levels have been determined.
IV.2. The measurements were higher in some
areas (playgrounds, classrooms, etc.).
Shouldn't the kids be prevented from
entering those areas?
We cannot provide such advice, because we do not
yet fully understand the risks, if any, of exposure
to electric and magnetic fields. We have very
little information on what scientists call "dose-
response," that is, how much of a given exposure
is how harmful, if at all.
IV J. How do we get our school measured?
Your school officials may call your local electric
utility or health department. Many power
companies offer free electric and magnetic field
testing. They may even have an office or
individual who will assist the public with EMF
questions. If not, your utility may know of private
firms in your area who make such measurements
or the phone directory may list environmental
consultants who make EMF measurements. You
may also be able to find someone who advertises
in EMF trade publications such as Microwave
News. EMF Health and Safety Digest, or in
computer magazines. Magnetic field meters can
be leased or purchased; many of the meters aren't
too expensive or hard to use. Most of the
manufacturers provide instructions that should be
carefully followed in order to assure accurate
results. EPA does not keep a list nor recommend
or certify private contractors who make
measurements.
IV.4. I heard that a nearby school had its
schoolyard measured. I know the values.
Is my schoolyard the same?
No, each schoolyard's magnetic field levels must be
measured or calculated separately. An EMF
measurement represents the intensity of electric or
magnetic fields. The intensity of the fields
decreases with distance from a source. Depending
on where your schoolyard is located with respect to
the power system, the field levels can vary. In
addition, EMF levels are dependent upon the
amount of current flowing through the electric
power system. Field levels can also vary with tune
and weather conditions as a result of differences in
electricity use for things such as air conditioners.
FV.5. Our children use VDTs at school. Is that
safe?
VDTs, like other electrical appliances, generate
electric and magnetic fields. VDTs have been a
source of great concern not so much because the
fields around them are greater than other sources,
but because many of us spend so much of our time
so close to them. VDTs also represent a relatively
new and growing technology. Some
epidemiological studies suggest no health risks from
EMF exposures from VDTs, while some studies
suggest a potential risk. Thus the health risks
associated with VDTs are inconclusive.
IV.6. Can't the computer be set up to minimize
exposure?
Yes, fields from VDTs can be reduced by
reorganizing the workplace or changing how VDTs
are used:
Work stations can be arranged so that an operator
sits at least an arm's length from the monitor. Most
people sit that far away anyway. At that distance,
the fields produced by the monitor are usually less
than background levels of EMFs from lights and
building wiring.
13
December 1992
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The same practice could be applied to how close IV.8. Besides power lines, substations, and
you are to machines operated by other people. VDTs, what are other common sources of
Held levels are sometimes highest at the sides and EMFs in schools?
back of a VDT. .The field strength decreases
rapidly with distance from the terminal. Levels at, All electrical and electronic products are to varying
say, two feet have dropped substantially. degrees sources of electric and magnetic fields.
Therefore, it is possible to organize VDT These products are found at home, at work, and at
equipment to reduce exposure from a neighboring school. Copy machines, cordless telephones,
VDT. fluorescent lights, electric typewriters, word
processors, printers, fax machines, coffee makers,
IV.7. Can you tell me about low emission vending machines, microwave ovens, and building
VDTs and screens that are supposed to wiring are some of the typical sources of electric
block EMFs? We were thinking about and magnetic fields. Schools may have some
buying that sort of equipment for our additional devices or tools in laboratories or
school if it works. industrial arts workshops. In general, all electrical
appliances and wiring can be considered to be
Computer manufacturers are beginning to design sources of EMFs.
and produce computers that emit lower electric and
magnetic fields. Several computer magazines have V. TRANSFORMERS
recently reported measured fields around various
models of VDTs (for example, MacWorld V.I. What are transformers?
December 1990 and Info World November 1990).
But it would be wise to verify any "low emission" Transformers are electrical devices used to adjust
claims by a manufacturer with measurements made the voltage-current relationship of an electrical
by such independent sources. power circuit for best efficiency during
transmission, distribution, and use. Utility
There might be some tradeoffs between low companies use a variety of transformers throughout
emission VDTs and other VDTs for cost, their systems. Step-up transformers are used at the
availability, and machine capabilities. It is best to power generating station to raise the voltage so the
contact manufacturers for details on their products, power can be economically delivered over
transmission lines. Step-down transformers are
One way manufacturers reduce magnetic fields in used to reduce the transmission line voltage for
computers is to place a metal called "mu metal" distribution of electrical power to our homes.
around the coils that produce the fields. The
fields are stifl present, but the metal has the Transmission and distribution substations, located
capability to contain them. where a main line has to feed a number of lower-
voltage lines, are fenced yards containing
Laptop computers are different. The display transformers and other electrical equipment.
screens on laptop computers do not use the Overhead (pole-mounted) transformers are used
cathode ray tube technology that emits EMFs from where distribution lines are overhead, and surface
VDTs. However, the battery packs and chargers (pad-mounted) transformers are used where
mat laptops use sometimes produce fields around distribution lines are underground. Frequently in
them like any electrical device. . urban situations the substations (or equivalent) are
- located within buildings.
Screens that are placed on the front of the monitor
help block glare and may reduce electric fields,
but they do not shield against magnetic fields.
14 December 1992
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V.2. What is that metal electrical box on the
corner of my lot.
If the electric distribution fines in your
neighborhood are underground, the boxes you see
in your neighborhood are probably surface (pad-
mounted) transformers. Each transformer
provides electrical service to several different
residences (typically four to eight) in your
neighborhood.
VJ. Do EMFs come from transformers?
There are electric and magnetic fields near the
transformer and the fines that connect to them.
This is because there is electricity running through
the boxes. But, the fields tend to drop off very
quickly as you move away from the transformers.
Pad-mounted transformers can produce elevated
magnetic fields close to their surface which are
generally comparable to levels from other devices
that use electric motors such as air conditioner
compressor units.
V.4. Aren't there chemicals in the
transformers?
Some older transformers contain an insulating fluid
called polychlorinated biphenyls (PCBs) that are
harmful to humans and the environment. But,
PCBs have not been used in new transformers
since the 1970's, and their use is being phased out
in accordance with EPA regulations. You could
consult your local electric company about
transformers and PCBs.
.V.5. Are transformers safe?
Transformers produce electric and magnetic fields.
The fields from transformers are localized and
decrease rapidly with distance. These fields are
no different than fields from other sources. We
do not know whether various levels of exposure to
EMFs are harmful or not.
The high voltage equipment inside the box
covering a pad-mounted or surface transformer can
cause electrical shocks or bums, if touched. But
pad-mounted transformers are required to meet local
ordinance requirements for safety and so are
insulated to protect against electrical shock hazards.
Nevertheless, transformers should not be treated as
toys or playground equipment. Children should be
discouraged from playing on or near pad-mounted
transformers or climbing trees near pole-mounted
transformers. Your power company can provide
you with further information on safety practices
they follow for transformers.
VI. REAL ESTATE
VI.l. What are the regulations about EMFs that
pertain to houses and real estate
transactions?
At the present time there are no federal regulations
or guidelines about power frequency EMFs. There
are presently no state or federal regulations about
EMFs and real estate transactions.
VI.2. What do I tell people about the power
fines behind my house?
There are no federal requirements that obligate you
to inform buyers about power lines or EMF levels
in your house. In spite of the uncertainty about
whether EMFs are hazardous, some state and local
governments may set limits on EMF levels or
may set some requirements, such as notification
about EMF levels, for real estate transactions.
Check with your state or municipality about local
rules and regulations on EMFs.
VL3. Should I buy/rent a house near a power
fine or substation?
The evidence on EMF effects is not clear enough to
determine whether or not locating near a power line
or a substation presents any health problem. But we
do know that field levels decrease as distance from
a source increases. With high voltage transmission
lines, the field intensity drops off after a few
hundred feet to "background" levels. There are
charts in many brochures that show field levels at
15
December 1992
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various distances for several kinds of power lines. decelerating. Studies are underway to try to define
Occupants of the average household are probably exposures, and to determine whether or not
exposed to higher fields from their house wiring exposure to electric and magnetic fields from
and appliances than from the outside wiring. transportation systems, results in health effects.
Being close to power lines or substations could VIL3. I've heard about "Prudent Avoidance."
affect a property's value simply for aesthetic What is that? How can I apply it to my
reasons; some people might find that situation to life?
be a nuisance or unattractive. This issue may be
only one of many factors to weigh and judge when Prudent avoidance is an approach to making
making real estate decisions. decisions about risks. This decision-making process
is based on judgment and values, can be applied by
VI.4. If I am buying a house, can I get the groups and individuals, and can be considered for
seller to test for EMFs? all aspects of our lives, not just EMFs. Prudent
avoidance applied to EMFs suggests adopting
If you are considering buying a house and would measures to avoid EMF exposures when it is
like EMF measurements made, any agreement reasonable, practical, relatively inexpensive and
about who pays for them would be between the simple to do. This position or course of action can
buyer and the seller. In many areas, the utility be taken even if the risks are uncertain and even if
company wfll make tests upon request at no safety issues are unresolved. Prudent avoidance
charge. decisions about all sorts of risks are made by people
every-day. For example, we decide whether it is
VII. MITIGATION within our ability and desire to avoid possible
hazards from activities such as driving automobiles,
VIL1. How can I stop the fields from coming sun tanning, and participation in sports. Individuals
into my house? Can't I shield them? make their own decisions based on their lifestyle,
their concerns about risks, and their willingness to
There is no simple way to block EMFs since the assume some cost or burden for a given action.
fields are generated by the electrical system and U.S. EPA has no official policy on prudent
devices in the home including the wiring and avoidance of EMF exposure. Until the health issues
appliances. Electric fields from outside the home are clearer, it is entirely up to individuals to decide
(power lines, etc.) are shielded to some extent by if they wish to take actions which may or may not
natural and building materials, but magnetic fields reduce any potential health risks.
are not The further a building is from an EMF
source, the weaker the fields at the building would The idea of applying the concept of prudent
be. Keeping fields out of the home would mean avoidance to EMF exposures was developed in a
keeping any electricity from coming into or being report written by Carnegie Mellon University, for
used in the home. Often the fields from sources the Office of Technology Assessment, tilled
inside the home (e.g., appliances, wiring, etc.) "Biological effects of Power Frequency Electric and
will result in higher fields than from sources Magnetic Fields: Background Paper". Some
outside the home. - examples of prudent avoidance from that report are:
(1) "... put away their electric blanket (or
VII.2. I commute on the subway/train - are electrically heated water bed) and go back to using
there fields there? Is it safe? regular blankets.;" (2) "... a motor driven electric
clock ... may produce a fairly strong magnetic field
Electrically-powered trains do produce electric and by your head ... you could move it... or replace it
magnetic fields, especially when accelerating and . with one of the newer digital clocks ..."
16 December 1992
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VIL4. How can I avoid EMFs?
EMFs are produced by an electrical devices and
electronic devices - power lines, microwave ovens,
home wiring, appliances, light fixtures, VDTs,
etc. It would be impossible to avoid EMFs
completely, but field levels get lower the farther
you are away from sources.
VBL5. What can be done to assure that new
transmission/distribution lines have low
fields? Can fields be completely
eliminated?
You should direct questions of concern to the
utility in question and to your state commissions
that regulate placement (siting) of the lines. They
should be able to provide information as to the
calculated field strength of the proposed lines.
State officials can provide you with information on
any EMF regulations that might be in effect for
your state.
All electrical devices produce EMF. There are
designs that can reduce electric and magnetic field
levels. However, the effectiveness and cost of
these measures varies with the type of application
(e.g., appliances, transmission lines, etc.). Fields
cannot be eliminated, but rapidly decrease with
distance. Research is underway on additional
designs to reduce electric and magnetic field
levels. Research on the configuration of
transmission lines may allow reduction in field
strength when transmission capacity is increased.
Vn.6. What can be done to reduce fields from
existing transmission/distribution lines?
Can fields be completely eliminated?
Questions should be addressed to the utility which
operates the line and appropriate state agencies to
see if the line in question meets state EMF
regulations, if any exist. All electrical devices as
well as power lines emit electric and magnetic
fields. EMFs cannot be completely eliminated as
long as electricity is used. Research on ways to
reduce fields from power lines and appliances is
being studied, especially by the utility industry.
Controlling exposures and field levels is termed
mitigation, field management, or control technology
engineering.
Vn.7. What can be done to reduce or eliminate
exposure in homes?
Electric and magnetic fields cannot be completely
eliminated, if we want to have electricity and
electrical appliances and other devices. As long as
electrical devices are used, EMFs will be produced.
Consultation with builders, architects or engineers
might help identify some building practices that
should reduce EMF exposure.
Vn.8. What are utilities/manufacturers doing
about reducing EMF exposure?
Questions concerning reduction of electromagnetic
fields can be addressed directly by the utility or
appliance manufacturers. The industry, primarily
through the Electric Power Research Institute
(EPRI), is conducting research and development on
field management techniques. Government agencies
and other countries are also working on field
management techniques.
VDTs PLUS THE OFFICE
ENVIRONMENT
Vm.1. 1 am concerned about EMFs and my
VDT. What is the bottom line?
VDTs have been a source of concern not so much
because the fields around them are greater than
other sources, but because many of us spend so
much of our time so close to them. There are
several different kinds of health effects that have
been suggested but not proven to be associated with
EMFs. Currently available information is
insufficient to conclude that electric or magnetic
fields are carcinogenic. Studies of other health
effects possibly associated with exposures from
VDTs have been inconclusive. In the meantime, if
you are concerned, you may want to arrange your
work stations so that you sit at least an arms length
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from your monitor. Most people sit that far away
anyway. At that distance, die fields produced by
your monitor are usually less than background
levels of EMFs from lights and building wiring.
VHL2. What can you ten me about low
emission VDTs and screens that are
supposed to block EMFs?
Computer manufacturers are beginning to design
and produce computers that emit lower electric and
magnetic fields. Several computer magazines have
recently reported measured fields around various
models of VDTs (for example, MacWorld
December 1990 and Info World November 1990).
But it would be wise to verify any "low emission"
claims by a manufacturer with measurements
by such independent sources.
VDTs (for example, MacWorld December 1990 and
Info World November 1990). If you choose to buy
a "low emission" VDT, you might verify any "low
emission" claims by a manufacturer with
measurements made by such independent sources.
Vm.4. Who else can I talk to about different
VDTs and claims about low fields and
"safe" monitors?
The Center for Devices and Radiological Health
(CDRH) in the Food and Drug Administration
(FDA) is the federal agency with primary
responsibility for controlling emissions from specific
electrical and electronic consumer products such as
VDTs. If you have some specific scientific or
technical questions, the FDA would be your best
source of information.
There might be some tradeoffs between low The National Institute for Occupational Safety and
emission VDTs and other VDTs for cost, Health (NIOSH) has also conducted research on
availability, and machine capabilities, ft is best to VDTs and office workers, and may be able to
contact manufacturers for details on their products, provide you with information.
One way manufacturers reduce magnetic fields in
computers is to place a metal called "mu metal"
around the coils mat produce the fields. The
fields are still present, but the metal has the
capability to contain them.
Laptop computers are different The display
screens on laptop computers do not use the
cathode ray tube technology that emits EMFs from
VDTs. However, the battery packs and chargers
that laptops use sometimes produce fields around
them like any electrical device.
VHI3.1 read an ad that said this company's
VDTs were safe and certified by EPA to
have little/no EMFs. Is that true?
No, it is not The EPA does not have any
certification program, guideline, or standards for
VDTs. Nor has EPA tested VDT emissions. The
VDT may have low field emissions, or it may not
Several computer magazines have recently
reported measured fields around various models of
The Occupational Safety and Health Administration
(OSHA) has a brochure on VDT use. In addition to
EMFs, the brochure has some helpful information
on the use of VDTs to avoid problems such as
eyestrain.
Vm.5. How do I contact the FDA, NIOSH, or
OSHA?
The phone number for the Director of FDA's
Center for Devices and Radiological Health is (301)
443-4690. If you call, ask to be directed to
someone who can help answer questions about
VDTs. Or, if you wish to write, the address for
FDA is:
Center for Devices and Radiological Health
U.S. Food and Drug' Administration
5600 Fishers Lane
Rockville, Maryland 20857
The FDA also has district offices throughout the
country.
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The group in the National Institute of Occupational
Safety and Health (NIOSH) that deals with EMFs
is based in Cincinnati, Ohio. You can call (513)
533-8482, or write to:
Physical Agents Effects Branch
NIOSH
4676 Columbia Parkway
Cincinnati, OH 45226
You fan write to the Occupational Safety and
Health Administration (OSHA) at:
OSHA
U.S. Department of Labor
Technical Data Center, N2439
200 Constitution Avenue, NW
Washington, D.C. 20210
VHI.6. Are VDTs different than my television?
VDTs and TVs are similar in design and
operation. Both produce fields that can be similar
in magnitude depending on the particular model or
size of the unit. Some very large televisions might
have higher fields than are emitted by your PC's
VDT. Fields tend to be highest at the back, sides,
and top of both devices rather than the front where
you usually are. Color screens generally have
higher fields than black and white or monochrome
screens. The reason that people were advised to
sit about 6 feet or more from a television is that
some very early televisions produced a very small
amount of weak X-rays (ionizing radiation ). The
solid state electronic circuitry of modern TVs in
combination with thick picture tubes with lead
have eliminated the problem of X-ray exposure.
VHL7. How far should I sit from my VDT?
What about from other people's VDTs?
There is not sufficient scientific information to say
whether VDT emissions cause any health problems
or not. However, sitting an arms length from
your VDT greatly reduces your exposure to the
field produced by it. (This is about where you sit
anyway.) The same common sense rule could be
applied to how close you are to machines operated
by other people. When placing computers and
VDTs, remember that fields tend to be highest at
the back, sides, and top of VDTs rather than in
front where the operator sits.
Vm.8. Why doesn't the U.S. have VDT
standards like Sweden?
Actually the Swedish standard has not yet been
ratified. Some of the standards are based on what
is practical and easy for manufacturers to design
and engineer in their products rather than on safety
and health considerations. In general, we do not
believe there is sufficient information about the
health effects of EMFs to write responsible health-
based guidelines for VDTs or other sources. We
aren't even sure that the field strength is the most
important thing to limit or reduce. For example,
many scientists believe that changes in field levels
may be more important biologically than the
average value or magnitude of the fields.
You might want to discuss VDT standards in
Europe with the Food and Drug Administration
(FDA). The Center for Devices and Radiological
Health (CDRH) in the Food and Drug
Administration (FDA) is the federal agency with
primary responsibility for controlling emissions
from specific electrical and electronic consumer
products such as VDTs. If you have some specific
scientific or technical questions, the FDA would be
your best source of information.
^
Vm.9. I've heard that laptops are safe. Is this
true?
The display screens on laptop computers do not use
the cathode ray tube technology that emits EMFs
from VDTs. The battery packs and chargers that
laptops use sometimes produce fields around them.
Vm.10. Is there someone who can come to
our office to measure EMFs?
EPA does not keep such a list nor recommend or
certify private contractors who make measurements.
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December 1992
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Yon may be able to find someone who advertises
in EMF trade publications or in computer
magazines or listed in your telephone directory.
Your local utility may be able to measure fields
outside of your building free of charge, but they
may not be willing (some are) to measure VDTs
or other sources in your office or home. Ait, the
utility may know of private firms in your area who
could make such indoor measurements. Field
meters can be purchased. Many of the meters
.aren't expensive or hard to use, but be sure to
learn how to use them properly. Manufacturers
usually provide instructions. (Also consult
Chapter 2 when responding to questions on
measurement.)
Vm.ll. What are other common sources
of EMFs ID the office?
Copy machines, cordless telephones, fluorescent
lights, electric typewriters, word processors,
printers, fax machines, coffee makers, vending
machines, microwave ovens, transformer rooms,
and building wiring are some of the typical
sources of electric and magnetic fields that are
found in modern offices. In general, all electrical
appliances and wiring can be considered to be
sources of EMFs. But it is important to remember
mat field strength decreases rapidly with distance.
EL RESEARCH
IX.1. Isn't all research being done by the
utilities?
Much of the research in the past and at present has
been funded by utilities largely through their
research organization, the Electric Power Research
Institute (EPRI). Federal agencies such as the
Department of Energy, including its Bonneville
Power Administration, have conducted and
continue to support research. Research is also
being sponsored by many foreign countries. Hie
States of New York and California have supported
research.
EL2. Isn't that (utility) work biased?
The utilities are interested in determining whether
or not exposure to EMF causes health effects. The
research sponsored by the utility industry (typically
performed by independent researchers) has been of
high quality. This research has identified bioeffects
and has suggested potential relationships between
certain exposures and specific health effects and has
contributed to our understanding of EMF effects.
EL3. What research is underway now?
World-wide, there are more than 230 research
projects underway, including epidemiological
studies, laboratory studies on biological effects, and
exposure and measurement studies.
IX.4. Why isn't the federal government doing
more research?
The federal government has expended over $60
million in the past on EMF research. The rate of
expenditure decreased in the early and mid-eighties,
but increased to over $10 million in FY 92. There
is currently a process underway to coordinate
research among the federal, state, and private
efforts.
EX.5. Why is the federal government so slow hi
responding?
This is largely due to the need to develop consensus
between the executive and legislative branches of
the government on what areas, out of the many high
priorities faced by the government, are most clearly
in need of support It is only fairly recently that
some consensus has grown to resolve that EMFs are
an issue deserving more careful and extensive study.
STANDARDS AND REGULATIONS
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~ X.I. Can the federal government make the
power company move/change the
transmission/distribution lines?
No, we cannot make the power company move or
change power lines. Utility power line siting and
operations are regulated by states and local
governments.
X.2. Can the federal government stop the
power company from putting in that new
line or increasing the voltage?
No, we cannot stop the power company from
making changes in their system. These sorts of
actions are regulated by local or state
governments.
X.3. What is a right-of-way (ROW)?
A right-of-way (ROW) is the area of land around a
power line, usually most visible around a
transmission line, that the utility uses. They
typically extend 50-65 feet from the center of the
line(s).
X.4. Measurements at the edge of the ROW
are higher than state rules. What should
I do to make the power company fix
this?
Call the power company and talk it over. They
may be willing to check it out for you. Or, they
may be able to make additional measurement to
compare to yours. Lots of factors can affect
measurements and different instruments or meters
may produce variable results. If you are still
unsatisfied after talking to the utility, contact your
local or state regulatory authority.
X.5. Why have some states written or
proposed standards for EMFs?
Several states have standards of limits for electric
or magnetic fields at the edge of ROWs. These
states are Montana, Minnesota, New Jersey, New
York, North Dakota, Oregon, and Florida.
Electric field limits are most common. Some of
these limits are old; some are new. Generally,
since the potential health risks of EMF exposure is
not known, several states took action to limit EMF
exposure to present levels along existing ROWs.
That is, exposures are not permitted to go any
higher.
X.6. Why hasn't the federal government
regulated EMFs?
Utilities are usually regulated by state and local
authorities. In any event, the data on health effects
from exposure to EMF is insufficient to establish
responsible health-based standards.
U.S. Environmental Protection Agency
Region 5, Library (PM?.i)
77 West Jackson BGU^V^J, 12th Floor
Chicago, IL 60604-3590
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