effect of emf on human being
TRANSCRIPT
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1
By
Mohammed Osama Abdel Rahman
El Samadony
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Preface
There is much public concern about the issues surrounding the
effects of electromagnetic fields on health in particular, the
potential health effectsofnewcommunication technologies such
as mobile telephones. This report extensively describes what
electromagnetic fields are, where they are found, and what is
being done to investigate their potential for affecting our health.
There are maximum exposure limits that are reviewed in the
light of scientific researches.__________________________
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CONTENTS
Chapter1 Introducton!!!!!!!!!!!!!!!!!!!"" #
1.1 Overview
1.2 Thegrowingconcern !
Chapter$ Characterstcs of Electroma%netc felds !!!!!!"! &2.1 "hysics of #$%s &
2.2 Theelectromagnetic spectrum '
Chapter' Sources of Electroma%netc feld !!!!!!!!!!""" 1(
(.1)atural sources 1*
(.2 $an+made sources 1!
Chapter) EM* Impact on En+ronment!!!"""!!!!!!!!"" $) .1 -uman being 2
.2 nimals 2/
.( 0egetation 2' . uatic ife (*
Chapter# Standards and ,udelnes !"!!!!!!!""!!!!""""" '1
References!!!!!!!!!!!"!"!!!!!!!""!!!!""""" '#
(
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A--RE.IATIONS
E/* #xtremely ow %reuency
EM* #lectromagnetic %ield
ICNIRP 3nternational 4ommission on )on+3oni5ing 6adiation
"rotection
IEEE 3nstitute for the #lectric and #lectronic #ngineersNIR )on+3oni5ing 6adiations
R* 6adiofreuency
0. 7ltraviolet
2O 8orld -ealth Organi5ation
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Chapter1
INTRO30CTION
1"1 O+er+e45
6ecentyearshaveseenanunprecedentedincreaseinthenumberand
diversityofsourcesof electricandmagneticfields9EM*:usedfor
individual,industrialandcommercialpurposes. ;uchsourcesinclude
televisions,radios,computers,mobilecellularphones,microwave
ovens, radarsandeuipmentsusedinindustry,medicineandcommerce.
llthesetechnologieshavemadeourlifericherandeasier.$odern
societyisinconceivable withoutcomputers,televisionandradio.$obile
phoneshavegreatlyenhancedtheabilityof individualstocommunicate
witheachotherandhavefacilitatedthedispatchofemergency medical
andpoliceaidtopersonsinbothurbanandruralenvironments.6adars
ma.
;imultaneously,thesetechnologieshavebroughtwiththemconcerns
aboutpossiblehealth ris
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Thereisalsoconfusionaboutthebiologicaleffectsofnon-ionizing
radiations9e.gradio waves,microwaves,etc.:versusionizingradiations
suchas?+raysandgammarays =1>.
Theconflictbetweenconcernsaboutpossiblehealtheffectsfrom
exposureto#$%andthe developmentofelectricitysupplyand
telecommunicationsfacilitieshaveledtoconsiderable economic
conseuences.%orexample,electricalutilitiesinmanycountrieshave
hadtodivert highvoltagetransmissionlinesaroundpopulatedareasand
evenhalttheirconstruction.The installationofbasestationsformobile
telephonesystemshasbeendelayedorhasmet oppositionfromthe
publicbecauseofconcernsthatthe6%emissionsfromthesebase
stationsmightcausecancerinchildren.3nthe7nited;tates,for
example,/@ofthetotal numberofbasestationsneededhaveyettobe
constructed =1>.
$easurestosignificantlyreduceelectricandmagneticfieldsinthe
environment,belowwhatisnowcommonlyaccepted,arecostly.3thas
beenestimatedthatconcernsabout#$%and healtharenowcostingthe
7nited;tateseconomyaloneabout0S6 1bllonannually. -owever,
ifunacceptablehealthris.
1"$ The ,ro4n% Concern5
3n the last two decades, awareness has increased for this health ha5ard
problem and many institutions both public and private, expressed great
interests in the electromagnetic fields impact on environment as a global
issue and the human health as specific issue, resulting in a more precise
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definitions for the problem and standards that ensures its elimination or
reduction.
ll over the world, numerous studies have been carried out on the
possible effects of electromagnetic fields on humans, animals, plants and
cell or tissue cultures, and a series of large+scale epidemiological surveys
has also been conducted.
Aased on these research results and upon evaluations of biological
effects that have been established to have health conseuences, The
3nternational 4ommission on )on+3oni5ing 6adiation "rotection
934)36": developed a guidline for emf exposure limits =2>.
Bisparities in #$% standards around the world have caused increasing
public anxiety about #$% exposures from the introduction of new
technologies. Therefore, the 8orld -ealth Organi5ation 98-O:
commenced a process of harmoni5ation of electromagnetic fields 9#$%:
standards worldwide. %uture standards will be based on the results of the
8-OCs 3nternational #lectromagnetic %ield "roDect =2>.
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Chapter$
C2ARACTERISTICS O*
E/ECTOMMA,NETIC *IE/3S
$"1 Physcs Of EM*s5
8hen current flows in a wire, there is also a magnetic field generated
around it, which is the fundamental concept behind an electromagnet =(>.
This magnetic field radiates away from the wire in a circular fashion 9%ig.
1:. The combination of these two fields is what we call an
electromagnetic field 9#$%: =>. The electric field describes the force
created by electric charges, and the magnetic field describes the force
caused by moving charges in the form of electric current.
Fig. 1 Electromagnetic field around a conductor [4].
#lectric fields are produced by voltage and increase in strength as the
voltage increases. The electric field strength is measured in units of volts
per meter 90Em:. $agnetic fields result from the flow of current through
wires or electrical devices and increase in strength as the current
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increases. $agnetic field strength is usually measured in units of ampere
per meter 9 m1:. related uantity is magnetic flux density, measured
in tesla 9T:. The other unit freuently seen in the literature is milligauss
91* mF G 1 HT: =>.
The electric and magnetic fields that combine to form an electromagnetic
wave travel at right angles to each other and to the direction of motion. 3n
following figure 9%ig. 2:, imagine this electromagnetic wave front
traveling to the right of the page. The electric field 9Ejjjjjjjjjjjjjj
: in this illustration
consists of waves that rise and fall in a vertical plane, while the waves of
the magnetic field 9Hjjjjjjjjjjjjjjjjjj
: vibrate bac< and forth on a hori5ontal plane. These
waves, vibrating at right angles to each other, are inseparable and cannot
be defined individually. 3n other words, an oscillating field of electrical
energy will always create a magnetic field, and a moving magnetic field
will always create an electrical fieldI one causes and depends on the
other, and, together they form electromagnetic radiation =(>.
Fig. 2 A schematic view of an electromagnetic field propagating along the Z-axis.
he electric Ejjjjjjjjjjjjjj
and magnetic Hjjjjjjjjjjjjjjjjjj
fields oscillate in the x-! plane
and perpendicular to the direction of propagation ["].
'
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3n general, the electricity supply produces undistorted sinusoidal
waveforms with a freuency of *+!* -5. -owever, in some situations
the #$%s may contain additional freuency components called
harmonics, which are multiples of the fundamental freuency.
#lectric fields are shielded or wea
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at an enormous speed, the speed of light. The freuency simply describes
the number of oscillations or cycles per second, while the term
wavelength describes the distance between one wave and the next.
The freuency of an electromagnetic wave is simply the number of
oscillations which passes a fixed point per unit of time. 3t is measured in
cycles per second, or hert5. One cycle per second euals one hert5 9-5:.
arge divisions commonly used to describe radio freuency 96%: fields
include the
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ultraviolet 970: radiation, visible light and ?+ray radiation.
#lectromagnetic waves at low freuencies are referred to as
Kelectromagnetic fieldsK and those at very high freuencies are called
Kelectromagnetic radiationsK. ccording to their freuency and energy,
electromagnetic waves can be classified as either Kionizing radiationsK or
Knon-ionizing radiationsK 9)36: =>.
a7 Ion8n% radatons5
The freuency of ioni5ing radiation is measured in millions or
trillions of hert5 9cycles per second:. The energy contained in a
given photon is proportional to its freuency, which means that the
higher the freuency, the higher the energy. The tremendous photon
energy of ?+rays and gamma rays 9because of their extremely high
freuencies: is capable of changing the internal structure of atoms
and molecules, as well as being immensely penetrating. This is the
sort of radiation we associate with radioactive substances such as
uranium, radium, and radiation emitted during atomic and
thermonuclear explosions. 3oni5ing radiation has sufficient energy
to cause actual chemical changes to ta.
b7 Non9on8n% radatons5
)on+ioni5ing radiations is a general term for that part of the
electromagnetic spectrum which has photon energies too wea< to
brea< atomic bonds. They include ultraviolet 970: radiation,
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visible light, infrared radiation, radiofreuency and microwave
fields, extremely low freuency 9#%: fields, as well as static
electric and magnetic fields.
#ven high intensity )36 cannot cause ioni5ation in a biological
system. )36, however, have been shown to produce other
biological effects, for instance, by heating, altering chemical
reactions or inducing electrical currents in tissues and cells=>.
Fig. 5 Electromagnetic spectrum,!pes of E#$ adiation.
1(
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Chapter'
SO0RCES O* EM*s
The sources of power freuency #$%s are divided broadly into those
produced by natural processes and those generated by human activity.
)aturally occurring #$%s arise from electrical processes associated with
the #arth and the atmosphere. 3n most environments the dominant sourceof exposure is that associated with the generation, transmission and use of
electricity. "eople are exposed directly through the use of electrical
appliances or euipment, or incidentally through wor. The proportion of each type of radiationemitted by the sun is shown in the diagram 9%ig. !:J
;everal measurements made in high uote atmosphere show that a
surface of 1 cm2, adsorbing solar energy perpendicularly to the solar rays,
adsorbs a heat uantity of 1'/( calorie for each minute. This number is
said solar constant. Aeing 1calorie G 1/ Doule the solar constant in the
3nternational ;ystem is given by 1(/* Noule per m2and per sec. These
1
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data corresponds to an electrical field of &** 0Em and to a magnetic field
of 2. microtesla. The centre of the spectrum of the solar radiation is
given by a wavelength of 1* nm corresponding to green light =(>.
Fig. 6 Electromagnetic radiation from the sun.
'"1"$ Electrc and ma%netc feld of the earth5
;tatic electric and magnetic fields 9constant fields: of significant field
strength have always existed on this planet.
The movement of air in the atmosphere and the ionising effect of cosmic
radiation in the higher regions, the ionosphere, create a field of direct
electric current between the surface of the #arth and the ionosphere.
7nder normal weather conditions, the field strength near the ground is
around 1**+** 0Em, whereas it can rise to 2*,*** 0Em 92*
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strengths can occur in the vicinity of lightning 9up to 1 T, which can cause
heart failure in humans:. ;mall variations in flux density are induced by
the solar wind, which distorts the earthCs magnetic field due to its streams
of charged particles. %urthermore, global storm activity also results in
high+freuency components within the magnetic field. -owever, these are
so small that at * -5 the alternating field component is merely 1*+!T
=&>.
Fig. 7 atural electric 'direct( and magnetic 'constant( fields [/].
'"$ Man9Made Sources5
'"$"1 Po4er lnes5"ower transmission lines bring power from a generating station to an
electrical substation. "ower distribution lines bring power from the
substation to your home. Transmission and distribution lines can be either
overhead or underground. Overhead lines produce both electric fields and
magnetic fields. 7nderground lines do not produce electric fields above
ground but may produce magnetic fields above ground.
1!
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Power transmission lines5 -igh voltage lines in most of the world
have a voltage of 1(2
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Fig. #agnetic $ield from a +33-5 ransmission 0ine
#easured Ever! + #inutes for 2 6ee=>.
Power distrib!tion linesJ Typical voltage for power distribution
lines ranges from to 2 .
Power s!bstations" 3n general, the strongest #$% around the
outside of a substation comes from the power lines entering and
leaving the substation. The strength of the #$% from euipment
within the substations, such as transformers, reactors, and capacitor
ban
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substation fence or wall, the #$% produced by the substation
euipment is typically indistinguishable from bac.
#able 1 !pical magnetic field strength of household appliances at various distances [7].
Electrc applance ' cm dstance
:;T7
'( cm
dstance :;T7
1 m dstance
:;T7
Refr%erator *. 1.& *.*1 *.2 Q*.*1
Colour T. 2. + * *.* 2 *.*1 *.1
Portable rado 1! ! 1 Q *.*1
Iron / (* *.12 *.( *.*1 *.*(
3sh4asher (. 2* *.! ( *.*& *.(
ashn% machne *./ * *.1 ( *.*1 *.1
Mcro4a+e o+en &( 2** / *.2 *.!
'"$"' or
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#xposure assessment studies so far have shown that most peoplePs #$%
exposure at wor< comes from electrical appliances and tools and from the
buildingPs power supply. "eople who wor< near transformers, electrical
closets, circuit boxes, or other high current electrical euipment may have
!*+-5 magnetic field exposures of hundreds of milligauss or more. 3n
offices, magnetic field levels are often similar to those found at home,
typically *. to .* mF. -owever, these levels can increase dramatically
near certain types of euipment =>.
The following figures 9%ig. 1*: are examples of magnetic field exposures
determined with exposure meters worn by four wor
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Fig. 1$ #agnetic $ield Exposures of 6orers 'm8(=>.
Table+2 may give a general idea about magnetic field levels for different
Dobs and around various
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)owadays, mobile telephony is commonly used all over the world. This
wireless technology relies upon an extensive networ< of fixed antennas,
or base stations, relaying information with radiofreuency 96%: signals.
Over 1. million base stations exist worldwide and the number is
increasing significantly with the introduction of third generation
technology =1*>.
$obile phone handsets and base stations present uite different exposure
situations. 6% exposure to a user of a mobile phone is far higher than to aperson living near a cellular base station. -owever, apart from infreuent
signals used to maintain lin
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ground. These antennas emit 6% beams that are typically very
narrow in the vertical direction but uite broad in the hori5ontal
direction. Aecause of the narrow vertical spread of the beam, the
6% field intensity at the ground directly below the antenna is low.
The 6% field intensity increases slightly as one moves away from
the base station and then decreases at greater distances from the
antenna =1*>.
Typically within 2+ meters of some antenna mounted on rooftops,
fences
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Chapter)
EM* IMPACT
ON EN.IRONMENT
"rotection of the environment and conservation of nature has become
matter of great interest to the public, as well as to governments. "ublic
concern about environmental exposure to #$% has ranged from claims of
reduced mil< production in cows gra5ing under power lines to damage to
trees near high power radars. Therefore, the 3mpact of #lectromagnetic on
environment was studied in numerous researches. review of the results
of such studies is summari5ed as followsJ
)"1 2uman ben%5
K#lectro+smogK is the bu55word which has directed public awareness
towards technical field emissions in recent years. ll over the world,
numerous studies have been carried out on the possible effects of
electromagnetic fields on humans, animals, plants and cell or tissue
cultures, and a series of large+scale epidemiological surveys has also been
conducted. The effects of electromagnetic fields generally depend on the
freuency and intensity, but also on individual characteristics such as
body si5e or angle towards the field =&>.
%indings have been largely substantiated with regard to the effects of
induced eddy currents at higher and medium+range field strengths 9%ig.
2
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11:, and these have formed the basis for the limit values in protective
legislation =&>.
Fig. 1$ %chematic &istri*ution of Edd! 9urrents :nduced *! #agnetic $ields
of 0ongitudinal and ransversal ;rientation owards the
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#lectromagnetic waves can be characteri5ed by their wavelength,
freuency, or energy. The three parameters are interrelated. #ach
influences the effect the field may have on a biological system.
The 3nternational #$% "roDect of 8-O is addressing the health concerns
raised about exposure to radiofre,!enc* (F)and microwave fields,
etremel* low fre,!enc* (/F)fields, and static electric and magnetic
fields. These electromagnetic fields can produce different biological
effects that may lead to health conseuences =11>.
adiofre,!enc* (F) fields"are .
6% fields at freuencies above about 1 $-5 primarily cause
heating by moving ions and water molecules through the medium
in which they exist. #ven very low levels of 6% energy produce a
small amount of heat, but this heat is carried away by the bodyCs
normal thermoregulatory processes without the person noticing it.
number of studies at these freuencies suggest that exposure to
6% fields too wea< to cause heating may have adverse health
conseuences, including cancer and memory loss. 3dentifying and
encouraging coordinated research into these open uestions is one
of the maDor obDectives of the 3nternational #$% "roDect.
6% fields at freuencies below about 1 $-5 primarily induce
electrical charges and currents which can stimulate cells in tissues
such as nerves and muscles. #lectrical currents already exist in the
body as a normal part of the chemical reactions involved in living.
3f 6% fields induce currents significantly exceeding this
2!
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bac
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and currents, other effects have been established to occur that could
potentially lead to adverse health conseuences, but only at very high
field strengths.
;tatic electric fields do not penetrate into the body, but can be
perceived by s.
;tatic magnetic fields have virtually the same strength inside the
body as outside. 0ery intense static magnetic fields can alter blood
flow or change normal nerve impulses. Aut such high field
strengths are not found in everyday life. -owever, there is
insufficient information about the effects of long+term exposure to
static magnetic fields at levels found in the wor
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;pecies, in particular certain fish, reptiles, mammals and migratory
birds, which rely on the natural 9geomagnetic: static magnetic field
as one of a number of parameters believed to be used for
orientation and navigational cues
%arm animals 9e.g. swine, sheep or cattle: gra5ing under power
lines 9*E!* -5: or in the vicinity of broadcasting antennas
%lying fauna, such as birds and insects that may pass through the
main beam of high power radio+freuency antennas and radar
beams or through high intensity #% fields near power lines.
;tudies performed to date have found little evidence of #$% effects on
fauna at levels below 34)36"Ps guideline levels. 3n particular, there were
no adverse effects found on cattle gra5ing below power lines. -owever, it
is
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)") A=uatc /fe
lthough all organisms are exposed to the geomagnetic field, marine
animals are also exposed to natural electric fields caused by sea currents
moving through the geomagnetic field. #lectro+sensitive fish, such as
shar
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Chapter#
STAN3AR3S
AN3 ,0I3E/INES
number of national and international organi5ations have formulated
guidelines establishing limits for occupational and residential #$%
exposure. The exposure limits for #$% fields developed by the
3nternational 4ommission on )on+3oni5ing 6adiation "rotection
934)36": + a non+governmental organi5ation formally recogni5ed by the
8orld -ealth Organi5ation 98-O:, were developed following reviews
of all the peer+reviewed scientific literature, including thermal and non+
thermal effects. The standards are based on evaluations of biological
effects that have been established to have health conseuences. The
main conclusion from the 8-O reviews is that #$% exposures below
the limits recommended in the 34)36" international guidelines do not
appear to have any
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Bespite of critici5ing of the 34)36" international guidelines as lacposure
lmts
*** 1** . ' 1*
(2
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;ome practical information will help to relate to the international
guideline values given above. 3n the following table 9Table :, the most
common sources of electromagnetic fields are listed. ll values are
maximum levels of public exposure =2>.
#able 5 !pical maximum pu*lic exposure
for the most common sources of electromagnetic fields[=].
Source Typcal ma>mum publc
e>posure
Electrc feld
:.?m7
Ma%netc flu>
densty :;T7
Mans po4er9in homes not close to
power lines:
1** *.2
Mans po4er
9beneath large power
lines:
1* *** 2*
Electrc trans and
trams(** *
T. and computer
screens
9at operator position:
1* *.&
Typcal ma>mum publc
e>posure :?m$7
T. and rado
transmtters*.1
Moble phone basestatons *.1
Radars *.2
Mcro4a+e o+ens *.
Bue to public anxiety in #gypt about mobile base stations, the )ational
Telecommunications 6egulatory uthority, )ational
((
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Telecommunications 3nstitute, $inistry of -ealth and "opulation, and
$inistry of ;tate for #nvironmental ffairs have thus Dointly produced a
modified manual of the reuired standards for installing mobile phone
base stations, up+to+date with the latest developments in
communications and information technology. This tripartite protocol
lists twelve conditions for the construction of cell sites as followJ
1. cell site must be constructed on a building that is 1 + * meters
high from surface, with the possibility of exceptions in case this is
not available.
2. The antenna must be higher than the other surrounding buildings
within a range of 1* meters.
(. The roof of the building on which the antenna is to be fixed must
be made of enhanced concrete.
. 3t is not permissible to fix more than one antenna on a single post.
. The distance between two cell sites must be at least 12 meters.
!. The distance between the antenna and the utmost reach of humans
must be at least ! meters.
&. ntennas may not be fixed on roofs that are not made of concrete.
/. ntennas may not be fixed on independent buildings, such as
hospitals.
'. ;ites must have a fence at a distance of ! meters from all
directions.
1*.4ompanies must adhere to the standards endorsed by the
merican 3nstitute for $easurements and the 3nstitute for the
#lectric and #lectronic #ngineers 93###:. The maximum
permissible power density a human being can be safely exposed
to must not exceed *. m8Ecm2 9'** $-S + 1/** $-S:.
11.ntennas may not be directed towards schools.
(
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12.%inally, pproval certifications that must be obtained are cited.
RE*ERENCES
1. 8-O, LElectromagnetic $ields and 1u*lic Health> the international E#$
pro?ect,M%act ;heet )o. 1/1, 8orld -ealth Organi5ation, $ay, 1''/.
2. 8-O, L6H; > %tandards and 8uidelines@Mavailable at
httpJEEwww.who.intEentityEpeh+emfEstandardsEenE
(. Aroo
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(!
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