Radiation Studies Divisionf6603J)

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Decrzemr 19926v0O-1-A L 1 V

Questions And AnswersAbout Electric And MagneticFields (EMFs)

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QUESTIONS AND ANSWERS ABOUTELECTRIC and MAGNETIC FIELDS (EMiFs)

i INTRODUCTON ............................................... I

I. BACKGROUND ................................................ 21.1. What are EMFs? .......................................... 2I.2. What are the sources of EMFs ........................................ 21.3. Are EMFs like X-rays? ............................................ 2I.4. What can EMFs do to me? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2I.5. .fjow do I reduce my exposure? ......................................... 3I.6. W hat is a gauss? .. .......................................... 3I.7. What is a safelevel? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3I.8. Is it true that levels below 2 milligauss (mG) are safe? Is there a standard? . . . . . . .. 4I.9. What is a safe distance from a magnetic field source? 4 . . . . . . . . . . . . . . . . . . . . . 4I.10. Why isn't the federal government setting a standard for EMF levels? Why have

some states set standards? 4 ...................................... 4I.11. Are there natural sources of EMFs? Are they like the fields created by power lines?

Can these cause health effects? 4...................................4

H1. MEASUREMENTS 5 ............................................... 51. 1. Do I need to get EM measurements? ........................... . 511.2. What will EMF measurements tell me? ................................ 511.3. How do I get my house or school measured? 5...........................5P 11.4. Does EPA recommend measurement contractors? . . . . . . . . . . . . . . . . . . . . . . . . . 5

11.5. Can I trust the measurements made by the utility'? ........................ 511.6. My neighbors had EMFs around their house measured. Is my house the same? ....-. 51.7. Can I make my own EMF measurements? 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.8. Where can I buy or rent a meter? 6 ................................. 611.9. Does EPA recommend meters? 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611.10. How much do meters cost? Which one is the simplest or best? 9 . . . . . . . . . . . . . . 611.11. How can I get instructions on how to make these measurements? ............... 711.12. How do I know how my readings compare to others"? ....................... 7

M.HEALTH .......................................................... 8JII.1. What can EMFs do to me? 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8M.2. What are cancer clusters? . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

- - .3. There are a lot of sick people in my neighborhood. There is [some source] here.Could that be the reason? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

111.4. Who should we contact when we suspect a cluster? 10......................1M.5. I can percieve electric and magnetic fields, what can I do? ................ .. .... 11M.6. I'm pregnant. Will ENIFs (or specific source) hurt me or my baby? ............. 11M.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

SCHOOLS ............................................. 12

December 1992i

rV.1. They've taken measurements in my child's school. I know what the measurementsare, 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? 1.................................13IV.4. I heard that a nearby school had its schoolyard measured. I know the values. -Is my

schoolyard the same? ............................................ 13rV.5. Our children use VDTs at school. Is that safe? ').......................... .13PV.6. Can't the computer be set up to minimize exposure? ...................... ... 13IV.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 itworks . .14 ....... 1wors.................................................1

IV.8. Besides power lines, substations, and VDTs, what are other common sources ofEMFs in schools? 14

V. TRANSFORMERS.................................................14V. 1. What are transformers? .............................................. 14V.2. What is that metal electrical box on the comer of my lot .................... 15V.3. Do EMFs come from transformers? ..................................... 15V.4. Aren't there chemicals in the transformers? ........................... 15V.5. Are transfonners safe? ......................................... 15

VI. REALESTATE ................................................. 15VI. 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? ................... 15VI.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 EM:Fs? ................ 16

VII. TIGATON.................................................... 16VI.1. How can I stop the fields from coming into my house?' Can't I shield them) ........ 16VII.2. I commute on the subway/train - are there fields there? Is it safe? ................ 16VIa.3. I've heard about "Prudent Avoidance." What is that? How can I apply it to my

-life? ................................................... 16VI.4. How can I avoid EMFs? 17........................................17VII.5. What can be done to assure that new transmission/distribution lines have low fields?

Can fields be completely eliminated? ............................. 17VIA6. What can be done to reduce fields from existing transmission/distribution lines?

Can fields be completely eliminated? ............................... 17VII.7. What can be done to reduce or eliminate exposure in homes? .................... 17VII.8. What are utilities/manufacturers doing about reducing EMF exposure? . . .' .............. 17

VIf. VDTs PLUS THE OFFICE ENVIRONME3NT.. ........................ 17VfI.l. I am concerned about EMFs and my VDT. What is the bottom line? ......... 17VMfl.2. What can you tell me about low emission VDTs and screens that are

h supposed to block EMFs? ...................................... 18

December 1992ii

VII.3.

VIII.4.

VIII.5.VIII.6.VIII.7.VIMI.8.VM.9.VIII.10.

- Vm.1I.

I read an ad that said this company's VDTs were safe and certified by EPAto have little/no EMFs. Is that true? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Who else can I talk to about different VDTs and claims about low fields and'safe" monitors? ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18How do I contact the FDA, NIOSH, or OSHA? ........................ . 18Are VDTs different than my television? . . . . .'............................. 19How far should I sit from my VD7? What about from other people's VDTs? . . 19Why doesn't the U.S. have VDT standards like Sweden . . . . . . . . . . . . . . . . . . 19I've heard that laptops are safe. Is this true? . . . . . . . . . . . . . . . . . . . . . . . . . . 19Is there someone who can come to our office to measure EMFs? ........... 19What are other common sources of EMFs in the office? . . . . . . . . . . . . . . . .. 20

IX. RESEARCH ......................................................IX.1. Isn't all research being done by the utilities9 . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IX.2. Isn't that (utility) work biased? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IX.3. What research is underway now? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IX.4. Why isn't the federal government doing more research? . . . . . . . . . . . . . . . . . . . ..

IX.5. Why is the federal government so slow in responding9. . . . . . . . . . . . . . . . . . . . .

202020202020

X. STANDARDS AND REGULATIONS ....................................... .20X.1. Can the federal government make the power company move/change the

transmission/distribution lines? .................................. 21X.2. Can the federal government stop the power company from putting in that new line

or increasing the voltage? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21X.3. What is a right-of-way (ROW)? ................................... 21X.4. Measurements at the edge of the ROW are higher than state rules. What should I do

to make the power company fix this? ................................ 21X.5. Why have some states written or proposed standards for EMFs? .............. 21X.6. Why hasn't the federal government regulated EMFs? . . . . . . . . . . . . . . . . . . . . . . .21

December 1992iii

i. INTRODUCTION

- he purpose of this document is to help EPA staffintter understand and respond to questions from

he public about electric and magnetic fields, alsoknown as EMFs. Scientific understanding of thepotential health risks from EMIF exposure is in anearly stage. Because the science is complicatedand the health issue unresolved, it is critical thatwe carefully explain what we know and don'tknow and not give contradictory messages. Wewant to provide information that is consistent andscientifically correct.

This document lists commonly asked questions andsuggested answers by topical area. The questionsand answers are given in a somewhat casual styleto simulate a telephone conversation. Some of thequestions anticipate issues that will arise in thecourse of a conversation. The questions andanswers were derived from the experience of EPAstaff, both at Headquarters and in the Regions,who routinely field inquiries from the public onEMFs. We do not expect that the answers will be_iven verbatim. Answers must be tailored to

*rond to the specific questions and needs of theer. The reader may find that some of the

answers seem repetitious. Repetition andreinforcement are here by design. The documentis designed so that the user can start at any topicof interest to callers without always having to referto background or related information in othersections. For example, some callers are onlyinterested in video display terminals (VDTs) atwork. Some are interested in schools, includingVDTs at schools. To meet both needs, somequestions and answers on VDTs are repeated.Most questions about EMFs concern sources anduses of electricity, namely 60 Hz power. Thequestions and answers in this booklet focus on 60Hz exposures rather than exposures from sourcestransmitting higher frequencies.

Certain basic ideas should be understood andtransmitted when responding to the public. Thefirst item on this list is a quote from the EPAScience Advisory Board review of the EPAdocument "Evaluation of the PotentialCarcinogenicity of Electromagnetic Fields"

1) "Some epidemiological evidence is suggestive ofan association between surrogate measurements ofmagnetic field exposure and certain canceroutcomes. In such studies, the existence ofconfounders is always a possibility, but since nocommon confounder has yet been identified, theexisting evidence can not be dismissed. In theabsence of much better exposure information and anunderstanding of which exposures are significant, noprecise exposure-response relationship has yet beenadduced. This lack, together with limitedunderstanding of possible biological mechanisms,prevents the inference of cancer causality from theseassociations at this time." In other words, there issome evidence that points to a relationship betweenEMFs and some types of cancer. Though the bodyof evidence can not be dismissed, it is not completeenough to draw meaningful conclusions.

2) Other health effects have not been studied asextensively as cancer so any possible relationshipwith EMF exposure is even more uncertain than thecancer issue.

3) Although the public tends to focus on exposurefrom transmission lines, for most people exposureto magnetic fields comes more from sources such asappliances and household wiring.

4) Research is being sponsored and conducted byboth government organizations and the electricalpower and products industry. A combinedgovernment and industry research effort is plannedfor 1993.

December 19921

1.4. What can EMFs do to me?

1.1. What are EMFs?

SEEMFs" is a shorthand term for "electric andmagnetic fields" or "electromagnetic fields."Electric and magnetic fields may occur alone or incombination and are a form of non-ionizingradiation. Examples of non-ionizing radiationinclude microwaves, visible light, and someultraviolet radiation. The American electric powersystem operates at 60 hertz (Hz). This means thatthe electric charges (current) flowing in the systemchanges direction 60 times a second. Althoughelectric and magnetic fields from 60 Hz exposuresare not considered "radiation" for various technicalreasons, they are still called "non-ionizingradiation"..-

I.2. What are the sources of EMFs?

Electric fields are produced by the presence ofelectrical charges, and magnetic fields areproduced by the movement of those charges.Electricity flowing in a wire or being used in an- pliance creates electric and magnetic fields. All

W wer lines and electrical appliances that drawcurrent have electric and magnetic fields aroundthem.

1.3. Are EMIFs like X-rays?

No. X-rays, microwaves and other radio waves,and the electric and magnetic fields from powerlines and and electrically powered appliances areall part of the electromagnetic spectrum. ButX-rays are a form of electromagnetic radiationwith high levels of energy. This energy issufficient to dislodge electrons from atoms that thex-ray strikes; a process called ionization which canresult in cancer. EMFs, microwaves and othersimilar types of electric and magnetic fields do notionize atoms because of their lower energy levels.

There are many unanswered questions raised by theresearch done so far. There. have been both positiveand negative studies. We are not sure if EMFexposure adversely affects human health. Morecareful and extensive study of EMFs is needed.

Since 1979, some studies of human populations,called epidemiology studies, suggest a potentialrelationship between exposure to EMPs and certaincancers. Unfortunately, there are manyuncertainties surrounding this information. Forexample, most of the epidemiological studies havevery limited information on what types of exposurewere experienced by the people in the studies. Theobserved increase in cancer was more pronouncedfor what are called "surrogates" or "indirect"estimates of EMF exposure than for electric andmagnetic fields measured using meters.' You mayhave heard about "wiring codes." Coding orcharacterizing houses according to the types ofnearby power lines has been one method to estimateEMF exposure in these studies. This is a"surrogate" of exposure.

The fact that disease incidence is correlated withsurrogate indexes for magnetic field exposure but'not with direct measurements, could be explained ineach of three ways or combination of these ways: a)the fields were different in the past, during the onsetof disease; than those measured later during thestudy; b) the wrong component or attribute of thefields was measured; and/or c) some other crucialfactor may be present which is unknowingly part ofwhat is being defined by the surrogate measure ofexposure. That factor could be some feature of theEMF exposure or something else altogether, such asa chemical exposure or differences in lifestyle.

Some laboratory studies have shown that extremelylow frequency (ELF) electric and magnetic fieldscan affect various activities of cells. The laboratorystudies on biological effects also are uncertain. Forexample, many of the positive results have onlybeen found in one laboratory. Usually, before a

2 December 1992

I. LACKGROUJND

2

result is accepted as proof by scientists, it has beenseen by several different investigators.

Additionally, it is not clear whether some of thebiological effects seen in laboratory studies of cellswould be harmful effects if they also occurred inpeople or whether they are minor changes that ourbodies-could adjust to.

The bottom line is that there is no establishedcause and effect relationship between EMFexposure and cancer or other disease. For thisreason, we can't define a hazardous level of EMFexposure.

It is known that one type of magnetic field canhave beneficial health effects. One treatment usedby doctors to help heal broken bones that are nothealing-nornally, is to expose the area for a fewminutes a day to a specific type of magnetic field.This apparently affects the body's capability forhealing bone.

I.5. How do I reduce my exposure?

e electric fields can be easily shielded,fields are much more difficult to shield.

ectric fields are shielded to some degree byalmost eveiything such as trees, bushes, walls, andso forth. Magnetic fields can be reduced byenclosing the source in certain types of metal suchas something called Mu metal which is a specialalloy. The fields are still present, but the metalhas the capability to contain them. This approachto reducing field levels is not practical for manysources, including power lines. (Some gadgetshave recently appeared on the market, such asbuttons,.peis, etc., claiming to shield one fromfields; it is almost certain that these do not work.)Magnetic field intensity can also be reduced byplacing wires close together so that the field fromone wire cancels the field from the other. This isnow-being done in new designs for electricblankets. To some degree the same thing can bedone for power lines, but for safety and reliabilityasons power lines have minimum required

Because of the way appliances are made, they havethe potential to have very high localized fields, butthen the fields decrease rapidly with distance. Forexample, typical magnetic field strengths not nearan appliance are 0.1 to 4 milligauss (mG), but thefield from an electric can opener can be 20,000 mGat 3 centimeters (approximately 1 inch) from theappliance. At 30 centimeters (approximately 1foot), appliance fields are usually around 1000 timeslower. For the can opener mentioned above, thelevel would probably be around 20 milligauss.

When you stand under a power line, you are alreadyat least 20 feet or more away from the line,depending on its height above ground. Under atypical 230 kilovolt transmission line the magneticfield is probably less than 120 milligauss. Incontrast, if you move about 100 feet away from theline, the magnetic field is probably about 15milligauss, and if you are 300 feet away from theline, the magnetic field is probably less than 2milligauss.

From these examples, we can see that distancefrom the source of the magnetic or electric field cansubstantially reduce exposure.

1.6. What is a gauss?

The gauss is a unit for the strength of a magneticfield, also known as magnetic flux density. Arelated unit used internationally for magnetic fluxdensity is the tesla. One tesla is equal to 10,000gauss. Magnetic flux density is measured in termsof lines of force per unit area. Remember thepatterns that were generated by iron filings on apiece of paper which was placed over a magnet?These patterns are field lines. .'We normally speakof magnetic fields in terms of thousandths of agauss or milligauss, abbreviated "mG."

I.7. What Is a safe level?

We don't know if EMF exposure is harmful (asidefrom the concern for electric shocks and burns forextreme exposure). We don't know if certain levelsof EMFs are safer or less safe than other levels.

December 19923

With most chemicals, we assume exposure athigher levels is worse than less exposure at lowerlevels. This may or may hot be true for EMFs

palso. More research is required to identify dose-response relationships. There is some evidencefrom laboratory studies that suggests that theremay be "windows" for effects. That means thatbiological effects are observed at some frequenciesand intensities but not at others. Also, we do notknow if continuous exposure to a given fieldintensity causes a biological effect, or if repeatedlyentering 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 EMFexposure."

I.8. Is it true that levels below 2 milligauss(mG) are safe? Is there a standard?

We do not yet know what if any magnetic fieldlevels are safe or unsafe. Th3 level of 2 mG is anarbitrary value used in some epidemiologicalstudies to place people in broad exposurecategories. Some other level could have been

-used. But, because no dose/response relationshipyet been determined for EMFs, we cannot

stablish a level which would be considered safeor unsafe.

As a result, neither the EPA nor any other federalregulatory agency has established a standard forEMIs.

I.9. What is a safe distance from a magneticfield source?

Since we do not know if EMF exposure isharmful, we don't know what intensity of field issafe' or unsafe. In turn, we cannot say what is asafe distance. A related question is, "At whatdistance is the strength of the field indiscerniblefrom the background field levels?" It depends onthe source of the magnetic field and the what thebackground field level is. Background magneticfields usually range from 0.1 to 4.0 illigauss

G). In the case of most high voltage powerSe s, at 300 feet from the center span, the

magnetic field has usually dropped below 2 mG. Inthe case of an electric can opener, the magneticfield is probably below 2 mG approximately 3 feetaway.

1.10. Why isn't the federal government setting astandard for EMF levels? Why have somestates set standards?

Several states have established standards for electricand/or magnetic fields at the edge of the right ofway for power lines, usually transmission lines.These standards either have been on the books for awhile, and are based on older scientific information,or were set more recently to establish levels ofexposure that should not be exceeded. Thestandards were intended to keep field levels fromgoing any higher, because of the existinguncertainty about health risks.

I.11. Are there natural sources of EMFs? Arethey lEke the fields created by power lines?Can these cause health effects?

Yes, there are natural sources. The earth has amagnetic field that is approximately 500 milligauss.The earth's magnetic field is relatively constant,meaning that it does not change very much withtime, unlike power lines. There are electromagneticfields associated with thunderstorms. Lightning is asource of EMFs. Some animals like sense naturalelectric and magnetic fields. Our bodies alsoproduce electrical fields that make our nervoussystems and hearts work. These internal electricfields are fairly high.

Batteries and some electrical systems also havefields that do not change with time; these are calledstatic or DC fields. DC stands for direct current.In contrasts, fields from most electrical powersystems and appliances vary in time and so arecalled time-varying fields or AC fields. AC standsfor alternating current. Electric power systems inthe United States operate at 60 Hz which cycles 60times per second.

December 19924

11. MEASUREMENTS

YI.1. Do I need to get ENMF measurements?

That's up to you. EPA neither recommends nordiscourages people from obtaining fieldmeasurements. You may decide to have EMFmeasurements made if you want to satisfy personalquestions, concerns, or curiosity about EMIFexposures.

1I.2. What will EMF measurements tell me?

Magnetic and electric field measurements will nottell you whether or not your exposure is harmfulor puts you at an increased risk, but they mayallow you to tell how your home compares to the"average" home. You should be aware that themeters typically used for home measurements canonly tell you "average field strength" in milligaussunits, at the time the measurements are performed.Even these measurements will vary over timebased on many factors, such as which appliancesare being used. EMF laboratory studies show that

hkiological effects may depend on one or more ofany aspects of exposure. like frequency, intensity,

oientation of the field, duration, transient orintermittent current, voltage spikes. Scientistsstill do not know what aspects of exposure, if any,are important. We therefore hove no. way ofestablishing either a safe or unsafe level. On thebasis of available scientific data, there is no wayof interpreting the health significance of EMFmeasurements.

IL3. How do I get my house or schoolmeasured?

Depending on where you live, your local powercompany may offer to conduct field measurementsaround your home. Additionally, your stateHealth Department or State Department ofEnvironmental Protection may also be able toprovide you with field measurements or refer youto consulting firms that conduct electric and

gnetic field measurements. Consulting firmsPy also be found through advertisements in

environmental and computer magazines. Thesefirms will perform EMP measurements usually for$200 - $300. Alternatively, you can buy your ownmeter for $75 and up. These meters usually comewith instructions.

11.4. Does EPA recommend measurementcontractors?

No. EPA does not recommend or endorse privatecompanies and contractors. EPA does not have aproficiency program - like the one for radon testingfirms - to measure the qualifications of contractorswho conduct electric and magnetic fieldmeasurements. Therefore, we cannot endorse orcomment on the qualifications of any contractor.The state of California is developing a list of firmsmaking ENM measurements. But the state is notrecommending or certifying these firms. To obtainthe list when it is completed, call (415) 540-2669 orwrite to the Special Epidemiology Studies Program,California Department of Health Services, 2151Berkeley Way, Room 704, Berkeley, CA 94704.

I1.5. Can I trust the measurements made by theutility?

Yes. Utilities should have the expertise and properequipment to make accurate measurements. Thereis no reason to believe that the utility is trying tomislead you by providing you with false readings.Since we do not understand very much about thepossible health effects of EMFs or what levels, ifany, might be hazardous, there is no reason for theutility to give you false results. It is important toremember that readings will vary depending onfactors such as the time of day the measurementswere taken. The differences in readings usuallyreflect how much electricity is being used by thepower system and other things, like what appliancesare being used.

II.6. My neighbors had EMFs around theirhouse measured. Is my house the same?

Probably not. Measurements in the house are oftenaffected by many sources of magnetic fields

December 19925s

including electrical appliances or power systemcomponents (transmission or distribution lines,transformers, or house wiring). Fields are even

roduced by "ground currents" flowing in waterpipes. EMFs decreases quickly with distance fromthe source. A power line or other source close toyour neighbor's house may generate a measurablefield there but levels at your house may be verydifferent.

EMPs can also be generated by many sources inaddition to power lines such as small appliances,hot water heaters, auxiliary power generators, andhousehold wiring. Since the presence of variouskinds of appliances varies from house to house, sodo EMF levels. Therefore, EMF levels in yourneighbor's house may be very different from thosein your own house.

11.7. Can I make my own EMfmeasurements?

Yes, but be sure to learn how to makemeasurements properly. Before using anyinstruments, you should educate yourself on the

e and degree of sensitivity, accuracy, and properwreration of the meter. This information can be

provided by the manufacturer. You could alsofollow recommendations from trade associationson how to measure fields. Table 1 includes somesources of measurement protocols.

Most simple magnetic field meters only readaverage field intensity, given in milligauss (mG).Measurements can vary with time, space, andpower load on the electrical system. Some metersonly measure magnetic fields. Some metersmeasure both electric and magnetic fields.Remember, even if you or someone else makes themeasurements properly, there is no basis forjudging the meaning of the data, relative topossible health effects.

11.8. Where can I buy or rent a meter?

luvertisements for companies that sell or rentters can be found in environmental or computer

magazines. Similar advertisements can also befound in scientific equipment journals, as well asnewsletters such as Microwave News, EMT Healthand Safety Digest and journals such as IEEESpectrum

Microwave News also maintains a directory ofcompanies which sell or rent magnetic field meters.We can send you a copy of that list, or you mayobtain a copy of this directory by sending a letterrequesting the "Gaussmeter Table" and a self-addressed stamped envelope and $1.00 for shippingand handling to:

Microwave NewsP.O. Box 1799Grand Central StationNew York, NY 10163

II.9. Does EPA recommend meters?

EPA does not recommend any specific supplier,manufacturer, or type of measurement equipment.

11.10. How much do meters cost? Which one isthe 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 arethree dimensional. Each dimension is called an"axis" (the plural is "axes"). To properly measurea magnetic field all three axes of the field should bemeasured-- horizontal (front), horizontal (side) andvertical. "Single-axis" meters measure only~oneaxis at a time and must be rotated until it is alignedwith the field. A three-axis meter can get anaccurate measurement no matter how it is orientedin the field, and they measure all three axes at thesame time. Single-axis meters are generally thecheapest; while three-axis meters which display anintegrated measurement (all three axes) are moreexpensive.

The less interpretation needed, the simpler aninstrument is to use, and readings are less subject toerror. Therefore, meters displaying an integratedmeasurement of all three axes together are the

December 19926

simplest to use. However, these meters tend to bemore expensive, and also have some additionalcapabilities that may be hard to learn and require acomputer. The single-axis meters are generallythe cheapest, but must be properly oriented.

II.11. How can I get instructions on how tomake these measurements?

There are protocols (intructions for standardizedmeasurement procedures) that can tell you how toperform the measurements. Table 1 is a list ofthesewprotocols, and where they may be obtained.Additional assistance may be available atuniversities with engineering or physicsdepartments. You may also wish to contact themanufacturer of the instrument for specificoperating guidance.

II.12. How do I know how my readingscompare to others?

Table 2 shows some typical magnetic fieldmeasurements near transmission lines. Yourutility company can tell you whether the line youare measuring is a transmission or distribution

*line. It is important to remember thatmeasurements may vary for a variety of reasonslike weather and operating conditions. Typicalresidential exposures, away from any appliances,rage from 0.1 mG to 4 mG.

This sort of information on typical values andcomparative exposures is also given in severalpublications such as those available from theBonneville Power Administration or in thebrochure prepared by Carnegie Mellon Universityentitled, Electric and Magnetic Fields from 60Hertz Electric Power: What do we know aboutpossible health risks.

TABLE 1SOURCES OF PROTOCOLS AND METHODSTO MEASURE ELECTRIC AND MAGNETIC

FIELDS

Electric and Magnetic Fields: Measurements andPossible Effects on Human Health fromAppliances, Power Lines, and Other CommonSources. May be obtained from:

Special Epidemiology Studies ProgramCalifornia Department of Health Services2151 Berkeley Way, Room 704Berkeley, CA 94704(415) 540-2669

IEEE Standard Procedures for Measurement ofPower Frequency Electric and Magnetic Fieldsfrom AC Power Lines. Standard 644-1987.

IEEE Measurements of Power FrequencyMagnetic Fields Away from Power Lines. 90 SM423-4 PWRD.

IEEE Guide for Measurement of DC ElectricField Strength and Ion Related Quantities.Report I.D.: SH13805. 1990.

All RBEE protocols may be obtained from:The Engineering Societies Library345 E. 47th StreetNew York, NY 10017(212) 705-7611

EEC Measurement of Power Frequency ElectricFields. International ElectrotechnicalCommission (EEC), Document 833. 1987.May be obtained from:

American National Standards Institute1430 BroadwayNew York, NY 10018(212) 354-3300

December 19927

TABLE 2

MAGNETIC FIELDS NEAR ELECTRIC POWER TRANSMISSION LINES

Types of ThansmissionLine

Maximum onRight-of-way

Distance from lines50' 100' 200'

115 Kilovolts (kV)

Average usagePeak usage

230 Kilovolts (kV)

Average usagePeak usage

500 Kilovolts (kV)

Average usagePeak usage

Magnetic Fields in milligauss (mG)

Information courtesy of Bonneville Power Administration.

E[[tHEALTH

1111. What can EMFs do to me?

There are many unanswered questions raised bythe research done so far. There have been bothpositive and negative studies. We are not sure ifEMF 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

lationship between surrogates for exposure to4FSs and certain cancers. Unfortunately, there

are many uncertainties surrounding this information.For example, most of the epidemiological studieshave very limited information on what types ofexposure were experienced by the people in thestudies. The observed increase in cancer was morestrongly associated with what are called"surrogates' or "indirect" estimates of EMFexposure than for electric and magnetic fieldsmeasured using meters. You may have heard about"wiring codes." Coding or characterizing housesaccording to the types of nearby power lines hasbeen one method to estimate EMF exposure in thesestudies. This is a "surrogate" of exposure.

December 1992

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The fact that disease incidence is correlated withsurrogate indexes for magnetic field exposure butnot with direct measurements, could be explained

each of three ways or combination of theseays: a) the fields in the past, during the onset of

disease, were different than those measured laterduring the study; b) the wrong component orattribute of the fields was measured; and/or c)some other crucial factor may be present which isunknowingly part of what is being defined by thesurrogate measure of exposure. That factor couldbe some feature of the EMF exposure orsomething else altogether, such as a chemicalexposure or differences in lifestyle.

Also, some laboratory studies have shown thatextremely low frequency (ELF) electric andmagnetic fields can affect various activities ofcells. The laboratory studies on biological effectsalso are uncertain. For example, many of thepositive results have only been found in onelaboratory. Usually, before a result is accepted byscientists as proof, it has been seen by severaldifferent investigators. Additionally, it is not clearwhetlier some of the biological effects seen in

boratory cellular studies would be harmfulffects if they also occurred in people or whether

they are minor changes that our bodies couldadjust to.

The bottom line is that there is no establishedcause and effect relationship between EMFexposure and cancer or other disease. -For thisreason, we can't define a hazardous level of EMFexposure.

On the other hand, it is known that one type ofmagnetic field can have beneficial health effects.One treatment used by doctors to help heal brokenbones that are not healing normally, is to exposethe area for a few minutes a day to a specific typeof magnetic field. This apparently affects thebody's capability for healing bone.

11I.2. What are cancer clusters?

The amount of disease (measured by either rates ornumber of cases) in any population or communitynaturally fluctuates somewhat over time. If youlook at enough populations or if you look at onepopulation for a long period of time, you wouldexpect to see an unusually large (or small) amountof disease once in a while. If the makeup of thecommunity changes, the amount and type of diseasealso changes. For example, a community withmostly older people will have more cases of chronicdiseases such as cancer or heart disease. Yetsometimes the amount of disease, usually a specificdisease, varies more than might be expected for agiven community. This unusual variation is called a"cluster.

It is often difficult to evaluate clusters. First, itmust be determined with statistical methods whethera truly unusual change has occurred or whether thisis only normal fluctuation. Second, the cause of thechange or cluster must be determined. This is thehard part, especially for chronic diseases. Cancer,like most diseases, has multiple causes; that is, nosingle reason can explain why one person getscancer and another does not. It may be relativelysimple to determine the cause of food poisoninghepatitis, or influenza clusters. But usuallyimpossible to clearly determine the cause of acancer cluster. Suspected EMF cancer clusters areeven more problematic because of the uncertainty ofEMF and cancer connections.

M.3. There are a lot of sick people in myneighborhood. There is [some source]here. Could that be the reason?

The following additional questions will often comeup 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 19929

It is important to realize that what seems to be anunusual excess may not necessarily be a greaterthan normal variation in the expected incidence ofhealth problems.' Especially in small communitieswhere people are familiar with many of the otherpeople in the area, one becomes aware of themany problems that do occur normally. If oneparticular kind of disease or health effect occursmany times in a community, the odds that someagent is a cause of the disease increases.3However, when the kinds of problems or diseasesvary it becomes.less likely that one particularagent is at work. Trying to weed out the healthcases that are not common to a particular agent, inorder to actually "see" the cluster, is an importantpart of the epidemiologist's job. This becomesvery important and at the same time very difficultfor an agent whose health effects are not wellknown and whose effects might vary from personto person.

EM~s are particularly difficult for epidemiologists.The problems that have been attributed by somepeople to EMFs include several different kinds ofcancer, birth defects, behavioral changes, slowede flexes, and spontaneous abortions. Therefore,e process of deciding which health problems in a

community belong to the "cluster" becomesexceedingly difficult. So...the answer to thequestion, "Can that source be the cause of myproblems?", is "maybe-niaybe not". The sourcemight be the problem but trying to show that it iscan be very difficult if not just impossible. Thehealth officials have to be good detectives as wellas competent health professionals. Because of thedifficulties, expense and uncertain results, unlessthe conditions are right, there is usually not muchvalue in conducting an epidemiological study.

One way to get measurements taken is to requestthat the utilities (in the case of power lines), or theowner of whatever source is of concern, performthe measurements. So far most health agencies donot have the staff, expertise or equipment toprovide that service. Private measuring businessesW being established to fill this demand but at this

e there is no licensing or quality assurance

available to indicate the qualifications of thesepeople.

Another problem associated with gettingmeasurements is that there really is little advice thatcan be given when the results are in. The standardsin effect are associated with very high field levels,so you can be reasonably certain that you won't bemeasuring anything near this range.

1.4. Who should we contact when we suspect acluster?

The first responder to calls of suspected clusters isthe local health department and then state healthagencies. When the state lacks a specific capability,the state may request assistance from EPA or fromthe Centers for Disease Control (CDC). EPA hasprovided EMF measurement assistance several timesover the past few years. CDC investigates healthproblems and disease outbreaks.

If you suspect that there are too many cases of aparticular disease in your community or if yoususpect that the health of people within yourcommunity is simply not what it should be, contactyour county health agency. They should havestatistics for the local areas and would be able todiscuss local issues. If they determine that aproblem exists and do not have the capability torespond properly, they will in turn requestassistance from the state authorities. Whileinvestigations of clusters and determinations ofclusters are very difficult, the suspected clustershould always be reported. Often, a closely.knitcommunity will be aware of health concerns beforean agency will. At other times, the agencies thatmaintain health registries will note statisticalincreases and initiate an investigation.

It is difficult to determine the possible causes ofclusters. People are exposed to many things in theirenvironment. And people have differing lifestyles.Any one agents might be responsible or manyagents might all be working together to producesome combined effect which is more significant thansimply the sum of their individual effects.

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1.5. I can percieve electric and magneticfields, what can I do?

The following questions will often come up in thissort of a discussion.

Why is this?Where is it coming from?Are there 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? .. .m2ke it stop?I know its from _ (source). Can youmake them stop?

Generally, humans appear unable to sense ordetect low levels of EMFs. Some animals havedeveloped this capability and use it for detectingand capturing prey and possibly for navigating.Yet, since these abilities evolved in some animals,it is possible that biological systems have at least avery rudimentary ability to respond to such fieldsand some people may be more sensitive thanothers. Additionally, there are "large" effects that

Nan be detected, such as static charges making theWme hairs on the body stand up, dental work actingafradio receivers, induced body currents whichmight be felt (if large enough) and possibly effectswhich we have not yet documented. 'Some peoplereport that they can "sense" low-level EMFs,however, this subject has not been studied verymuch.

We don't have much advice for people who saythey are sensitive to electric or magnetic fields.While grounding of sources might alleviate largestatic charges and dental work might reduce theradio effects, too little is known about the actualfield-body interaction to suggest anything furtherin terms of mitigation.

M;6. I'm pregnant. Will EMfs (or specificsource) hurt me or my baby?

This following additional questions will often comeLp in this sort of health discussion.

I work at a VDT all day long. Is that safe?We just moved into a home near powerlines. Will that hurt my unborn child?I just lost a baby. Could it be because of myelectric blanket (power lines, etc.)?

There are several issues to consider with respect toconcerns about pregnancy and EMF exposure:

1. Are EMFs harmful? There is insufficientscientific evidence to establish whetherEMFs are harmful. The EPA recentlyreviewed the scientific literature with respectto any potential cancer effect and concludedthat although some epidemiological studieshave shown an association between cancerand surrogates of EMF exposure, cause andeffect relationships have not beenestablished. Laboratory studies havedemonstrated that biological changes withincell and tissue cultures can be induced byEMFs, but these changes have not beenlinked to human health effects. EPA has notformally assessed potential reproductive anddevelopmental effects. These effects havenot been studied as extensively as cancer.The few epidemiological studies concerningreproductive effects have been inconclusive.

2. I have heard children are more sensitive?We have no evidence that children areespecially sensitive. Some of the firststudies concerned cancer and children, andreceived a great deal of attention. But therehave also been some occupational studiesdealing with adults that also found somecorrelations with potential exposure toEMFs.

3. - Are pregnant women and unborn childrenmore sensitive? We do not have enoughevidence to answer that question. Therehave been reports about clusters ofmiscarriage and birth defects among VDTusers or from electric blanket exposures.Some studies have been negative, and somehave been positive. This question has not be

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studied as extensively as cancer, and somay be viewed as even more uncertain.

How can exposures from VDTs and otherdevices be reduced?

a) By sitting at arms length from aterminal or pulling the keyboard back stillfurther; magnetic fields fall off rapidly withdistance.

b) By switching VDTs off (not thecomputer necessarily) when not in use.

c) By spacing and locating terminals in theworkplace, so that work stations areisolated from the fields from neighboringVDTs. Fields will penetrate partitionwalls, but do fall quickly with distance.

d) By using electric blankets (or water bedheaters) to warm beds but unplugging thembefore sleeping. Magnetic fields disappearwhen the electric current is switched off.However, electric fields may exist as longas a blanket is plugged in.

e) By not standing close to sources ofEMFs such as microwave ovens while inuse. Standards are in place to limitmicrowave emissions, however, the electricpower consumption by a microwave ovenresults in magnetic fields that are high closeto the unit. The same is true of otherappliances as well.

M.7. The EPA report is just about cancer, butI've heard there are other effects. Whatare they? Why hasn't EPA looked intothose effects?

Various bioeffects have been attributed to EMFs.These include behavioral changes in lab animals,altered circadian rhythms (daily metabolic andbehavioral cycles), altered levels of melatoninIduction (a hormone thought to play a role inocer 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 arehealth effects sometimes attributed to EMFs, butthere is not broad scientific support for suchassertions. Cancer is the most extensively studiedhealth effect, yet no cause and effect relationshiphas been established between EMF exposure andcancer, and no hazardous effect level can bedefined. The potential for other health effect shouldbe viewed as even more uncertain. EPA hasprepared a report describing the research needed toreduce the uncertainties in a health risk assessmentof EMF. These research needs address cancer,reproduction, development, the central nervoussystem, and the immune system as well asbiophysical mechanisms, exposure assessment, andcontrol technology.

IV. SCHOOLS

IV.1. They've taken measurements in my child'sschool. I know what the measurementsare, but what do they mean?

The measurements were probably made with aGaussmeter which is used to measure magneticfields. If so, the measurements represent theintensity of the magnetic fields in that location.Magnetic fields are produced by any source that.uses electricity, including components of the electricpower system (power transmission or distributionlines, transformers, or building wiring) andelectrical and electronic devices. Magnetic fieldsare even produced by "ground currents" flowing inwater pipes. The intensity of the magnetic fielddepends on the amount of electric current flowingthrough the electrical system or device.

While the possibility of a public health concern hasbeen raised in some epidemiological studies, we donot yet have enough information to say whetherEM~s pose a health risk or not. These same studieshelped us to understand that we need to learn moreabout what aspect of EMF exposure may be most

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relevant. For example, scientists do not knowwhether we should be concerned with the strength. of the field, the rate of change in the fieldstrength, the electric current induced in the body,or other variables or exposures completelyunrelated to electric and magnetic fields. Thismakes interpretation of field measurements verydifficult. Although not completely satisfactory,your measurement results can, however, becompared to others to see if yours are typical ornot. It must be remembered that no safe or unsafelevels have been determined.

IV.2. The measurements were higher in someareas (playgrounds, classrooms, etc.).Shouldn't the kids be prevented fromentering those areas?

We cannot provide such advice, because we do notyet fully understand the risks, if any, of exposureto electric and magnetic fields. We have verylittle information on what scientists call "dose-response," that is, how much of a given exposureis how harmful, if at all.

V .3. How do we get our school measured?

Your school officials may call your local electricutility or health department. Many powercompanies offer free electric and magnetic fieldtesting. They may even have an office orindividual who will assist the public with EMFquestions. If not, your utility may know of privatefirms in your area who make such measurementsor the phone directory may list environmentalconsultants who make EMF measurements. Youmay also be able to find someone who advertisesin EMF trade publications' such as MicrowaveNews, EATF Health and Safety Digest, or incomputer magazines. Magnetic field meters canbe leased or purchased; many of the meters aren'ttoo expensive or hard to use. Most of themanufacturers provide instructions that should becarefully followed in order to assure accurateresults. EPA does not keep a list nor recommendpr certify private contractors who makeleasurements.

IV.4. I heard that a nearby school had itsschoolyard measured. I know the values.Is my schoolyard the same?

No, each schoolyard's magnetic field levels must bemeasured or calculated separately. An EN{Fmeasurement represents the intensity of electric ormagnetic fields. The intensity of the fieldsdecreases with distance from a source. Dependingon where your schoolyard is located with respect tothe power system, the field levels can vary. Inaddition, EMN levels are dependent upon theamount of current flowing through the electricpower system. Field levels can also vary with timeand weather conditions as a result of differences in-electricity use for things such as air conditioners.

IV.5. Our children use VDTs at school. Is thatsafe?

VDTs, like other electrical appliances, generateelectric and magnetic fields. VDTs have been asource of great concern not so much because thefields around them are greater than other sources,but because many of us spend so much of our timeso close to them. VDTs also represent a relativelynew and growing technology. Someepidemiological studies suggest no health risks fromEMN exposures from VDTs, while some studiessuggest a potential risk. Thus the health risksassociated with VDTs are inconclusive.

IV.6. Can't the computer be set up to minimizeexposure?

Yes, fields from VDTs can be reduced byreorganizing the workplace or changing how VDTsare used:

Work stations can be arranged so that an operatorsits at least an arm's length from the monitor. Mostpeople sit that far away anyway. At that distance,the fields produced by the monitor are usually lessthan background levels of EMFs from lights andbuilding wiring.

1December 199213

The same practice could be applied to how closeyou are to machines operated by other people.[ield levels are sometimes highest at the sides andack of a VDT. The field strength decreases

rapidly with distance from the terminal. Levels at,say, two feet have dropped substantially.Therefore, it is possible to organize VDTequipment to reduce exposure from a neighboringVDT.

IV.7. Can you tell me about low emissionVDTs and screens that are supposed toblock EMFs? We were thinking aboutbuying that sort of equipment for ourschool if it works.

Computer manufacturers are beginning to designand produce computers that emit lower electric andmagnetic fields. Several computer magazines haverecently reported measured fields around variousmodels of VDTs (for example, MacWorldDecember 1990 and Info World November 1990).But it would be wise to verify any "low emission"claims by a manufacturer with measurements madeby such independent sources.

PIere might be some tradeoffs between lowemission VDTs and other VDTs for cost,availability, and machine capabilities. It is best tocontact manufacturers for details on their products.

One way manufacturers reduce magnetic fields incomputers is to place a metal called "mu metal"around the coils that produce the fields. Thefields are still present, but the metal has thecapability to contain them.

Laptop computers are different. The displayscreens on laptop computers do not use thecathode ray tube technology that emits EMPs fromVDTs. However, the battery packs and chargersthat laptops use sometimes produce fields aroundthem like any electrical device.

Screens that are placed on the front of the monitorAlp block glare and may reduce electric fields,A they do not shield against magnetic fields.

IV.8. Besides power lines, substations, andVDTs, what are other common sources ofEMFs in schools?

All electrical and electronic products are to varyingdegrees sources of electric and magnetic fields.These products are found at home, at work, and atschool. Copy machines, cordless telephones,fluorescent lights, electric typewriters, wordprocessors, printers, fax machines, coffee makers,vending machines, microwave ovens, and buildingwiring are some of the typical sources of electricand magnetic fields. Schools may have someadditional devices or tools in laboratories orindustrial arts workshops. In general, all electricalappliances and wiring can be considered to besources of EMFs.

V. TRANSFORMERS

V.1. What are transformers?

Transformers are electrical devices used to adjustthe voltage-current relationship of an electricalpower circuit for best efficiency duringtransmission, distribution, and use. Utilitycompanies use a variety of transformers throughouttheir systems. Step-up transformers are used at thepower generating station to raise the voltage so thepower can be economically dlivered overtransmission lines. Step-down transformers areused to reduce the transmission line voltage fordistribution of electrical power to our homes.

Transmission and distribution substations, locatedwhere a main line has to feed a number of lower-voltage lines, are fenced yards containingtransformers and other electrical equipment.Overhead (pole-mounted) transformers are usedwhere distribution lines are overhead, and surface(pad-mounted) transformers are used wheredistribution lines are underground. Frequently inurban situations the substations (or equivalent) arelocated within buildings.

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V.2. What is that metal electrical box on thecorner of my lot.

If the electric distribution lines in yourneighborhood are underground, the boxes you seein your neighborhood are probably surface (pad-mounted) transformers. Each transformerprovides electrical service to several differentresidences (typically four to eight) in yourneighborhood.

V.3. Do EMFs come from transformers?

There are electric and magnetic fields near thetransformer and the lines that connect to them.This is because there is electricity running throughthe boxes. But, the fields tend to drop off veryquickly as you move away from the transformers.Pad-motunted transformers, can produce elevatedmagnetic fields close to their surface which aregenerally comparable to levels from other devicesthat use electric motors such as air conditionercompressor units.

V.4. - Aren't there chemicals in theb transformers?

Some older transformers contain an insulating fluidcalled polychlorinated biphenyls (PCBs) that areharmful to humans and the environment. But,PCBs have not been used is- new transformerssince the 1970's, and their use is being phased outin accordance with EPA regulations. You couldconsult your local electric company abouttransformers and PCBs.

V.S. Are transformers safe?

Transformers produce electric and magnetic fields.The fields from transformers are localized anddecrease rapidly with distance. These fields areno different than fields from other sources. Wedo not know whether various levels of exposure toEMPs are harmful or not.

Ibhe high voltage equipment inside the boxWvering a pad-mounted or surface transformer can

cause electrical shocks or bums, if touched. Butpad-mounted transformers are required to meet localordinance requirements for safety and so areinsulated to protect against electrical shock hazards.Nevertheless, transformers should not be treated astoys or playground equipment. Children should bediscouraged from playing on or near pad-mountedtransformers or climbing trees near pole-mountedtransformers. Your power company can provideyou with further information on safety practicesthey follow for transformers.

VI. REAL ESTATE

VI.1. What are the regulations about Elfs thatpertain to houses and real estatetransactions?

At the present time there are no federal regulationsor guidelines about power frequency EMFs. Thereare presently no state or federal regulations aboutEMFs and real estate transactions.

VI.2. What do I tell people about the powerlines behind my house?

There are no federal requirements that obligate youto inform buyers about power lines or EMF levelsin your house. In spite of the uncertainty aboutwhether EMFs are hazardous, some state and localgovernments may set limits on EME levels ormay set some requirements, such as notificationabout EMF levels, for real estate transactions.Check with your state or municipality about localriles and regulations on EMFs.

VL3. Should I buy/rent a house near a powerline or substation?

The evidence on EMF effects is not clear enough todetermine whether or not locating near a power lineor a substation presents any health problem. But wedo know that field levels decrease as distance froma source increases. With high voltage transmissionlines, the field intensity drops off after a fewhundred feet to "background" levels. There arecharts in many brochures that show field levels at

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various distances for several kinds of power lines.Occupants of the average household are probably

-exposed to higher fields from their house wiringW d appliances than from the outside wiring.

Being close to power lines or substations couldaffect a property's value simply for aestheticreasons; some people might find that situation tobe a nuisance or unattractive. This issue may beonly one of many factors to weigh and judge whenmlaking real estate decisions.

VI4. If I am buying a house, can I get theseller to test for EMFs?

If you are considering buying a house and wouldlike EMF measurements made, any agreementabout who pays for them would be between thebuyer and the seller. In many areas, the utilitycompany will make tests upon request at nocharge.

VII. MITIGATION

VII.1. How can I stop the fields from coming*i into my house? Can't I shield them?

There is no simple way to block EMPs since thefields are generated by the electrical system anddevices in the home including the wiring andappliances. Electric fields from outside the home(power lines, etc.) are shielded to some extent bynatural and building materials, but magnetic fieldsare not. The further a building is from an EMFsource, the weaker the fields at the building wouldbe. Keeping fields out of the home would meankeeping any electricity from coming into or beingused in the home. Often the fields from sourcesinside the home (e.g., appliances, wirng, etc.)will result in higher fields than from sourcesoutside the home.

VII2. I commute on the subway/train - arethere fields there? Is it safe?

Aectrically-powered trains do produce electric and'gn etic fields, especially when accelerating and

decelerating. Studies are underway to try to defineexposures, and to determine whether or notexposure to electric and magnetic fields fromtransportation systems, results in health effects.

VUI.3. I've heard about "Prudent Avoidance."What is that? How can I apply it to mylife?

Prudent avoidance is an approach to makingdecisions about risks. This decision-making processis based on judgment and values, can be applied bygroups and individuals, and can be considered forall aspects of our lives, not just EMFs. Prudentavoidance applied to EMFs suggests adoptingmeasures to avoid EMF exposures when it isreasonable, practical, relatively inexpensive andsimple to do. This position or course of action canbe taken even if the risks are uncertain and even ifsafety issues are unresolved. Prudent avoidancedecisions about all sorts of risks are made by peopleevery day. For example, we decide whether it iswithin our ability and desire to avoid possiblehazards from activities such as driving automobiles,sun tanning, and participation in sports. Individualsmake their own decisions based on their lifestyle,their concerns about risks, and their willingness toassume some cost or burden for a given action.U.S. EPA has no official policy on prudentavoidance of EMIP exposure. Until the health issuesare clearer, it is entirely up to individuals to decideif they wish to take actions which may or may notreduce any potential health risks.

The idea of applying the concept of prudent.avoidance to EMF exposures was developed in areport written by Carnegie Mellon University, forthe Office of Technology Assessment, titled'Biological effects of Power Frequency Electric andMagnetic Fields: Background Paper". Someexamples of prudent avoidance from that report are:(1) a... put away their electric blanket (orelectrically heated water bed) and go back to usingregular blankets.;" (2) "... a motor driven electricclock ... may produce a fairly strong magnetic fieldby your head ..- you could move it ... or replace itwith one of the newer digital clocks ... "

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VII.4. How can I avoid EMFs?

s are produced by all electrical devices andnic evices - power lines, microwave ovens,

ome wiring, appliances, light fixtures, VDTs,etc. It would be impossible to avoid EMFscompletely, but field levels get lower the fartheryou are away from sources.

VII.5. What can be done to assure that newtransmission/distribution lines have lowfields? Can fields be completelyeliminated?

You should direct questions of concern to theutility in question. and to your state commissionsthat regulate placement (siting) of the lines. Theyshould be able to provide information as to thecalculated field strength of the proposed lines.State officials can provide you with information onany EMF regulations that might be in effect foryour state.

AU electrical devices produce EMF. There aredesigns that can reduce electric and magnetic fieldvels. However, the effectiveness and cost of

pese measures varies with the type. of application(&g., appliances, transmission lines, etc.). Fieldscannot be eliminated, but rapidly decrease withdistance. Research is underway on additionaldesigns to reduce electric and magnetic fieldlevels. Research on the configuration oftransmission lines may allow reduction in fieldstrength when transmission capacity is increased.

VJI.6. What can be done to reduce fields fromexisting transmission/distribution lines?Can fields be completely eliminated?

Questions should be addressed to the utility whichoperates the line and appropriate state agencies tosee if the line in question meets state EMIFreguVations, if any exist. All electrical devices aswell as power lines emit electric and magneticfields. EMFs cannot be completely eliminated asE as electricity is used. Research on ways to

ce fields from power lines and appliances is

being studied, especially by the utility industry.Controlling exposures and field levels is termedmitigation, field management, or control technologyengineering.

VII.7. What can be done to reduce Dr eliminateexposure in homes?

Electric and magnetic fields cannot be completelyeliminated, if we want to have electricity andelectrical appliances and other devices. As long aselectrical devices are used, EMPs will be produced.Consultation with builders, architects or engineersmight help identify some building practices thatshould reduce EMF exposure.

VII.S. What are utilities/manufacturers doingabout reducing EMF exposure?

Questions concerning reduction of electromagneticfields can be addressed directly by the utility orappliance manufacturers. The industry, primarilythrough the Electric Power Research Institute(EPRI), is conducting research and development onfield management techniques. Government agenciesand other countries are also working on fieldmanagement techniques.

Vm. VDTs PLUS THE OFFICEENVIRONMENT

Vf.1. I am concerned about EMFs and myVDT. What is the bottom line?

VDTs have been a source of concern not so muchbecause the fields around them are greater thanother sources, but because many of us spend somuch of our time so close to them. There areseveral different kinds of health effects that havebeen suggested but not proven to be associated withEMls. Currently available infonnation isinsufficient to conclude that electric or magneticfields are carcinogenic. Studies of other healtheffects possibly associated with exposures fromVDTs have been inconclusive. In the meantime, ifyou are concerned, you may want to arrange yourwork stations so that you sit at least an arms length

December 199217

from your monitor. Most people sit that far awayanyway. At that distance, the fields produced by

wyour monitor are usually less than backgroundWevels of EMFs from lights and building wiring.

VIII.2. What can you tell me about lowemission VDTs and screens that aresupposed to block EMFs?

Computer manufacturers are beginning to designand produce computers that emit lower electric andmagnetic fields. Several computer magazines haverecently reported measured fields around variousmodels of VDTs (for example, MacWorldDecember 1990 and Info World November 1990).But it would be wise to verify any "low emission"claims by a manufacturer with measurements madeby such independent sources.

There might be some tradeoffs between lowemission VDTs and other VDTs for cost,availability, and machine capabilities. It is best tocontact manufacturers for details on their products.

One way manufacturers reduce magnetic fields inAd omp is to place a metal called "mu metal"

- ~round the coils that produce the fields. Thefields are still present, but the metal has thecapability to contain them.

Laptop computers are different. The displayscreens on laptop computers do not use thecathode ray tube technology that emits EMFs fromVDTs. However, the battery packs and chargersthat laptops use sometimes produce fields aroundthem like any electrical device.

VIII.3. -I read an ad that said this company'sVDTs were safe and certified by EPA tohave little/no EMfs. Is that true?

No, it is not. The EPA does not have anycertification program, guideline, or standards forVDTs. Nor has EPA tested VDT emissions. TheVDT may have low field emissions, or it may not.

geveral computer magazines have recently- ported measured fields around various models of

VDTs (for example, MacWorld December 1990 andInfo World November 1990). If you choose to buya "low emission" VDT, you might verify any "lowemission" claims by a manufacturer withmeasurements made by such independent sources.

VIII.4. Who else can I talk to about differentVDTs 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 primaryresponsibility for controlling emissions from specificelectrical and electronic consumer products such asVDTs. If you have some specific scientific ortechnical questions, the FDA would be your bestsource of information.

The National Institute for Occupational Safety andHealth (NIOSH) has also conducted research onVDTs and office workers, and may be able toprovide you with information.

The Occupational Safety and Health Administration(OSHA) has a brochure on VDT use. In addition toEMFs, the brochure has some helpful informationon the use of VDTs to avoid problems such aseyestrain.

VM.5. How do I contact the FDA, NIOSH, orOSHA?

The phone number for the Director of FDA'sCenter for Devices and Radiological Health is (301)443-4690. If you call, ask to be directed tosomeone who can help answer questions aboutVDTs. Or, if you wish to write, the address forFDA is:

Center for Devices and Radiological HealthU.S. Food and Drug Administration5600 Fishers LaneRockville, Maryland 20857

The FDA also has district offices throughout thecountry.

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lTe group in the National Institute of OccupationalSafety and Health (NIOSH) that deals with EMFsis based in Cincinnati, Ohio. You can call (513)533-8482, or write to:

Physical Agents Effects BranchNIOSH4676 Columbia ParkwayCincinnati, OH 45226

You can write to the Occupational Safety andHealth Administration (OSHA) at:

OSHAU.S. Department of LaborTechnical Data Center, N2439200 Constitution Avenue, NWWashington, D.C. 20210

Vm.6. Are VDTs different than my television?

VDTs and TVs are similar in design andoperation. Both produce fields that can be similarin magnitude depending on the particular model orize of the unit. Some very large televisions might

higher fields than are emitted by your PC'sT. Fields tend to be highest at the back, sides,

and top of both devices rather than the front whereyou usually are. Color screens generally havehigher fields than black and white or monochromescreens. The reason that people were advised tosit about 6 feet or more from a television is thatsome very early televisions produced a very smallamount of weak X-rays (ionizing radiation ). Thesolid state electronic circuitry of modern TVs incombination with thick picture tubes with leadhave eliminated the problem of X-ray exposure.

VII.7. How far should I sit from my VDT?What about from other people's VDTs?

There is not sufficient scientific information to saywhether VDT emissions cause any health problemsor not. However, sitting an arms length fromyour VDT greatly reduces your exposure to the

joeld produced by it. (This is about where you sitMyway.) The same common sense rule could be

applied to how close you are to machines operatedby other people. When placing computers andVDTs, remember that fields tend to be highest atthe back, sides, and top of VDTs rather than infront where the operator sits.

Vm.8. Why doesn't the U.S. have VDTstandards like Sweden?

Actually the Swedish standard has not yet beenratified. Some of the standards are based on whatis practical and easy for manufacturers to designand engineer in their products rather than on safetyand health considerations. In general, we do notbelieve there is sufficient information about thehealth effects of EMFs to write responsible health-based guidelines for VDTs or other sources. Wearen't even sure that the field strength is the mostimportant thing to limit or reduce. For example,many scientists believe that changes in field levelsmay be more important biologically than theaverage value or magnitude of the fields.

You might want to discuss VDT standards inEurope with the Food and Drug Administration(FDA). The Center for Devices and RadiologicalHealth (CDRH) in the Food and DrugAdipinistration (FDA) is the federal agency withprimary responsibility for controlling emissionsfrom specific electrical and electronic consumerproducts such as VDTs. If you have some specificscientific or technical questions, the FDA would beyour best source of information.

VM.9. I've heard that laptops are safe. Is thistrue?

The display screens on laptop computers do ndt usethe cathode ray tube technology that emits EMFsfrom VDTs. The battery packs and chargers thatlaptops use sometimes produce fields around them.

vm.0o. Is there someone who can come toour office to measure EMGs?

* EPA does not keep such a list nor recommend orcertify private contractors who make measurements.

December 199219

You may be able to find someone who advertisesin EMF trade publications or in computer

Magazines or listed in your telephone directory.Dour local utility may be able to measure fieldsoutside of your building free of charge, but theymay not be willing (some are) to measure VDTsor other sources ir your office or home. But, theutility may know of private firms in your area whocould make such indoor measurements. Fieldmeters can be purchased. Many of the metersaren't expensive or hard to use, but be sure tolearn how to, use them properly. Manufacturersusually provide instructions. (Also consultChapter 2 when responding to questions onmeasurement.)

vm.11. 'What are other common sourcesof EMFs in the office?

Copy machines, cordless telephones, fluorescentlights, electric typewriters, word processors,printers, fax machines, coffee makers, vendingmachines, microwave ovens, transformer rooms,and building wiring are some of the typicalsources of electric and magnetic fields that areound in modern offices. In general, all electrical

appliances and wiring can be considered to besources of EMFs. But it is important to rememberthat field strength decreases rapidly with distance.

IX. RESEARCH

IX.1. Isn't all research being done by theutilities?

Much of the research in the past and at present hasbeen funded by utilities largely through theirresearch organization, the Electric Power ResearchInstitute (EPRI). Federal agencies such as theDepartment of Energy, including its BonnevillePower Administration, have conducted andcontinue to support research. Research is alsobeing sponsored by many foreign countries. TheStates of New York and California have supportedksearch.

IX.2. Isn't that (utility) work biased?

The utilities are interested in determining whetheror not exposure to EMF causes health effects. Theresearch sponsored by the utility industry (typically.performed by independent researchers) has been ofhigh quality. This research has identified bioeffectsand has suggested potential relationships betweencertain exposures and specific health effects and hascontributed to our understanding of EMF effects.

IX.3. What research is underway now?

World-wide, there are more than 230 researchprojects underway, including epidemiologicalstudies, laboratory studies on biological effects, andexposure and measurement studies.

IX.4. Why isn't the federal government doingmore research?

The federal government has expended over $60million in the past on EMF research. The rate ofexpenditure decreased in the early and mid-eighties,but increased to over $10 million in FY 92. Thereis currently a process underway to coordinateresearch among the federal, state, and privateefforts.

IX.5. Why is the federal government so slow inresponding?

This is largely due to the need to develop consensusbetween the executive and legislative branches ofthe government on what areas, out of the many highpriorities faced by the government, are most clearlyin need of support. It is only fairly recently thatsome consensus has grown to resolve that EMFs arean issue deserving more careful and extensive study.

X. STANDARDS AND REGULATIONS

December 199220

Keywords:Magnetic fieldsExposure assessmentExposure monitoring

EPRI TR-101407Project 2966-06Final ReportNovember 1992

Assessment of Children'sLong-Term Exposure to MagneticFields (The Enertech Study)

IVA CORPORATE LIBRARYCHATTAN OOGA, TENNESSEE

Prepared byEnertech ConsultantsCampbell, CaliforniaandHigh Voltage Transmission Research CenterLenox, Massachusetts

'RI> Powerrch Institute

Assessment of Children's Long-Term Exposure toMagnetic Fields (The Enertech Study)Epidemiologic studies investigating the possible relationship of mag-netic field exposures with cancer in children have relied on a varietyof surrogate indices to estimate exposure. These surrogates includewiring configuration codes as well as residential spot and 24-hourmeasurements. This pilot study suggests that exposure estimatesbased on the engineering characteristics of residential electricalsystems are no more accurate than estimates based on wiring codesor spot measurements.

INTEREST CATEGORIES

Electric and magneticfields

krhead distribution

Magnetic fieldsExposure assessmentExposure monitoring

BACKGROUND Several epidemiologic studies have reported a positive associa-tion between the wiring configuration of electric utility lines and childhood cancer.One hypothesis advanced to explain these findings is that the wiring configurationis a surrogate for long-term exposure to magnetic fields. However, in the two child-hood studies that have includedshort-term residential magnetic field measure-ments (spot and 24-hour measures), the association of magnetic fields with cancerhas been weak to nonexistent. To address hypotheses concerning the potentialrole of long-term residential magnetic field exposure in the associations of wiringconfiguration with cancer, improved techniques are needed to estimate childhoodexposure to magnetic fields over an extended period. The pilot study described inthis report, together with a companion pilot project (EPRI report TR-101406) con-ducted by Geomet Technologies, Inc., has attempted to identify the determinantsof childhood exposure to residential magnetic fields.

OBJECTIVE To evaluate whether engineering approaches to estimating residen-tial fields due to ground currents and outdoor line currents provide a valid basis forassessing magnetic field exposure.

APPROACH Investigators selected 35 homes representing a range of externalutility wiring and home grounding characteristics. During two visits to the studyhouses about half a year apart, they measured ground currents, indoor magneticfields (both 24-hour and spot), outdoor magnetic field profiles, and using a three-axis integrating meter (the AMEX-3D) also measured personal exposure. Theyalso collected data on residential power consumption and utility load on the distri-bution system during the measurement period. The investigators tested whetherengineering-based exposure estimates correlated with those measured on theAMEX-3D.

RESULTS Time-weighted-average (TWA) magnetic field exposure as recorded onthe AMEX-3D correlated significantly with both the power consumed within indi-vidual residences and the power flowing on the utility distribution system. Spot-measured fields were also associated with these quantities. However, comparedwith the use of spot-measured fields or the Wertheimer-Leeper wiring code, themodel incorporating residential consumption and utility loading did not improvethe predictability of personal exposure. In addition, temporal variation in theconsumption/loading data was not useful in predicting temporal differences inEPRI TR-lol 4o7s Electric Power Research Institute

R E P 0 H T S U M M A R Y

-.

Assessment of Children's Long-Term Exposure toMagnetic Fields (The Enertech Study)TR-101407Research Project 2966-06

Final Report, November 1992

Prepared byENERTECH CONSULTANTS300 Orchard City Drive, Suite 132Campbell, California 95008

HIGH VOLTAGE TRANSMISSION RESEARCH CENTERA Research Facility of theELECTRIC POWER RESEARCH INSTITUTEOperated byGENERAL ELECTRIC COMPANY1000 East New Lenox RoadLenox, Massachusetts 01240

Principal InvestigatorsW. T. KauneL. E. Zaffanella

Prepared forElectric Power Research Institute3412 Hillview AvenuePalo Alto, California 94304

EPRI Project ManagersS. S. SussmanR. Kavet

Electric and Magnetic Fields Health Studies ProgramEnvironment Division of

ABSTRACT

One of the major problems faced by most studies of the associationbetween disease and the exposure of children to power-frequency magneticfields is how best to use contemporary magnetic-field measurements toassess exposures that occurred in the past. One goal of the researchpresented in this report was to test the hypothesis that residentialpower consumption and utility neighborhood load flow data could be usedto improve the accuracy of historical exposure predictions. Two sets ofmagnetic-field data were collected in the spring and winter of 1990-1991for each of 30 homes located in Western Massachusetts and NorthernCalifornia. These data were used to characterize personal exposures andthe magnetic fields produced by ground currents, by sources locatedoutside the home, and by home appliances. In addition, the averageelectric powers consumed by the study homes during each of the two 24-hvisits were measured and the average electric powers supplied to theneighborhoods of the study homes during the two measurement periods wereestimated using data supplied by the local electric utilities. Spotmagnetic-field measurements were weakly to moderately associated withmeasured residential exposures. The precisions of the Wertheimer-Leepercode and spot measurements in predicting measured residential exposureswere similar. A source-oriented exposure model, that incorporatedground currents, external power lines, and home appliances, was able topredict measured personal exposures with about the same precision asobtained by just using time-weighted-average spot measurements.Residential spot and 24-h magnetic-field measurements were more stable,over a period of about eight months, than were measured personalexposures. The use of residential power consumption and utility loadflow data provided some help in explaining temporal changes inresidential spot and 24-h magnetic field measurements but little, ifany, help in explaining changes in measured exposures.- Time-weighted-average spot measurements were more effective than personal exposuremeasurements in predicting subsequent personal exposure measurements.The results of this study suggest that total residential exposurecontains a temporally stable component, which can be measured using spotmeasurements, and a substantially larger, temporally variable,component. Unless methods can be developed to describe this lattercomponent, or it can be shown that it becomes predictable when averagedover time periods longer than about one year, it appears that onlylimited precision can be obtained by using contemporary data to assesshistorical magnetic-field exposures.

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