Cell phones emitting pulsed high-frequency
electromagnetic fields (EMF) may affect the human brain, but there
are inconsistent results concerning their effects on electroencephalogram
(EEG). We used a 16-channel telemetric electroencephalograph (ExpertTMR),
to record EEG changes during exposure of human skull to EME emitted
by a mobile phone. Spatial distribution of EME was especially conce
ntrated around the ipsilateral eye adjacent to the basal surface
of the brain. Traditional EEG was full of noises during operation
of a cellular phone. Using a telemetric electroencephalograph (ExpertTMR)
in awake subjects, all the noise was eliminated, and EEG showed
interesting changes: after a period of 10-15 s there was no visible
change, the spectrum median frequency increased in areas close to
antenna; after 20-40 s, a slowwave activity (2.5-6.0 Hz) appeared
in the contralateral frontal and temporal areas. These slow waves
lasting for about one second repeated every 15--20 s at the same
recording electrodes. After turning off the mobile phone, slow-wave
activity progressively disappeared; local changes such as increased
median frequency decreased and disappeared after 15-20 min. We observed
similar changes in children, but the slow-waves with higher amplitude
appeared earlier in children (10-20 s) than adults, and their frequency
was lower (1.0-2.5 Hz) with longer duration and shorter intervals.
The results suggested that cellular phones may reversibly influence
the human brain, inducing abnormal slow waves in EEG of awake persons.
Keywords brain, brain mapping, cellular
phone, electromagnetic field
A cellular phone is a low-power, single-channel, two-way radio.
Cell phone base stations are low-power multi-channel two-way radios.
Therefore, base stations produce radio-frequency radiation, and
they expose people near them to radio-frequency (RF) radiation.
According to reports from the scientific community, the power from
the mobile phone base station antennas is far too low to produce
health hazards as long as people are kept away from direct access
the antennas. This nonionizing radiation is, however, fundamentally
different from the ionizing radiation produced by x-ray machines.
The effects of electromagnetic source to biological material depends
on the frequency of the source (see Moulder & Foster, 1995).
RE radiation, and EMF from power lines are part of the electromagnetic
spectrum, which are characterized by their frequency.
Electric power in Turkey is at 50 Hz, and at 60 HZ in the US. FM
radio has a frequency of around 100 MHz, microwave ovens have a
frequency of 2450 MHz, X-rays have frequencies above one million
GHz, and cellular phones operate at frequencies between about
800 and 2200 MHz. The electromagnetic particles of high-frequency
X-rays have sufficient energy to break chemical bonds (ionization),
which can damage the genetic material of cells leading to cancer
or birth defects. Low frequency RE radiation is nonionizing. Therefore,
there is no similarity between the biological effects of x-rays
and RF radiation.
There was no convincing evidence that radio fields-in
contrast to X- and Gamma-rays, ultraviolet and atomic radiation-can
directly cause the changes in genes responsible for cancer development.
Actually, most governments and cell-phone companies have claimed
that the only possible biological effect of RF transmission is localized
body heating. However, significant concern has been raised about
possible health effects of RF electromagnetic fields. For
instance, transgenic mice most susceptible to cancer demonstrated
2-times increase in tumor rate (B-cell lymphomas) after exposure
microwaves at a power density roughly equal to a cell-phone transmitting
for two half-hour periods each day, compared to control mice
unexposed to RF fields (Repacholi et al., 1997). Children might
develop cancer after exposure to the RF emissions from mobile
telephone base stations in or near schools (see Repacholi, 1997).
The human body is an electrochemical instrument controlled by
oscillatory electrical processes of various kinds; some endogenous
biological electrical activities can be interfered via oscillatory
of the incoming radiation. Human in vivo studies indicated
that the awaked EEC exposed to RE fields from a cell phone exerts
a delayed increase in spectral power density, particularly in the
band (Reiser, Dimpfel, & Schober, 1995). Exposure to mobile
phone radiation decreases the preparatory slow potentials in certain
regions of the brain (Freude, Ullsperger, Eggert, & Ruppe, 1998)
and affects memory tasks modulating the responses of EEG activity
approximately 8 Hz specifically during cognitive process (Krause
al., 2000). There is a lot of evidence indicating nonthermal influences
of RE fields in vivo, such as epileptiform activity in rats in
conjunction with certain drugs (Sidorenko & Tsaryk, 1999), depression
of chicken immune systems (Youbicier-Simo & Bastide, 1999),
increase in chick embryo mortality(Youbicier-Simo & Bastide,
increased permeability of blood-brain barrier in rats (Persson,
Brun et al., 1997), and synergistic effect with certain psychoactive
drugs (Lai, Horita, Chou, & Guy, 1987). These RF influences
induce many clinical signs and symptoms, such as headache, epileptic
seizure, and sleep disturbance. The current scientific literature
suggests that nonthermal RF field effects originating from cellular
phones may have potential adverse health reactions, and this possibility
should not be ignored even if only a small minority of people
are at risk (because of inconsistent results).
Concerning the human brain, the above mentioned
studies suggest that electromagnetic fields emitted by cellular
phones may affect the human EEG. The current scientific literature
is, however, full of inconsistencies. The aim of the present work
was to reinvestigate the effects of the pulsed high frequency EMFs
on human EEG in children and adults.
MATERIALS AND METHODS
Ten healthy young males and 10 children (12 years old) voluntarily
participated in the study. The subjects were healthy and free of
neurological and psychological signs and symptoms. During
sessions, the subjects were sitting on an arm chair within a soundisolated
room. Sixteen electrodes were placed over the scalp according
to the international 10-20 system, to record EEG. The reference
was the sum of all the electrodes (common reference). The
subjects were awake and their eyes were open during recordings,
which were made using a 16-channel telemetric electroencephalograph
made by one of us (AVK) (ExpertTM, Kharkov, Ukraine).
This device uses digital telemetry and allows recording for a long
time up to 24 h. EEG signals are transmitted digitally to the registration
device via radio frequencies. The wireless system significantly
simplifies the EEG examinations during research and clinical
use. It is much less sensitive to the pulse and systematic noise
any other stationary EEGs. The built-in processor allows us to carry
out digitization, filtration, compression, and coding of the signal
directly in the EEG-amplifier. This allows us to transmit digital
EEGs wirelessly with no interferences, including 50 Hz background
noise. The high input resistance allows using the standard EEG gel
for 24-hour EEG recording, reducing many physiological artifacts.
EEG was subjected to spectral analysis including multiple mapping
of amplitude characteristics and spectra of selected ranges. 3-D
of the functional focus was possible with availability
of arbitrary or MRI-compatible shear planes.
EEG recordings were made in awake subjects before
a call with a usual radiophone and a cellular phone. The carrier
frequency of our cell phone was 900 MHz with a frame-frequency
of 217 Hz. So, the usual radiophones provide continuous radiation
usually up to 100 MHz with an emitted power up to 3 mW, whereas
cell phones transmit the information in frames (217 Hz), the transmitter
works with zero power between frames. In the on mode, the
cell phone emits 3-4 W in immediate vicinity of the active ear and
brain structures. The effects of EMF emitted by cell phones is an
inverse proportion to squared distance. For instance, let us suppose
that the field strength is X during calling (phone is near ear,
tance = 1 cm); if we increase the distance to 10 cm, the field strength
decreases to X/100. When a person lives near a cellular station
W, distance = 50 m), the field strength decreases to (50/0.01)2
25000000 times. This is why the experiments cannot find any signs
of EEG changes when the transmitter is placed far from the skull
(40 cm or more) as reported by some investigators.
In order to understand the flow of current in a conducting medium
like the human brain, the isotonic NaCl solution was put in a container
and the antenna of a cellular phone was placed four cm apart
from this container. The current flowing in this conducting medium
could be registered using the weakly polarized Ag-AgCl EEGelectrodes
in a low-frequency oscillograph (see Figure 1). This experiment
suggests that potentials of several or tens of milivolts with
a pulse frequency of 217 Hz may occur within the brain structures
while using a cellular phone.
Fig1. A snapshot from an oscilloscope:
pulses emitted by a cellular phone recorded from an isotonic NaCl
solution using Ag-AgCl EEG electrodes. Each square shows the voltage
(vertical line = 2 mV) and time (horizontal line = 2 msec). Ericsson
A1018S 900 MHz phone. (See Color Plate II at end of issue.)
Figure 2 illustrates the map of the EMF generated by the cellular
phone. Notice the highly complicated spatial distribution of the
and its locking in the mediums with maximum conduction.
That is, the largest physiological effects will be strongly pronounced
in places with largest area of contact with liquid. The locking
EMF through the area of ipsilateral eyeball suggests that the influence
on the basal surface of the brain might be stronger than the
areas directly adjoining the antenna. All areas with intensive liquor
dynamics become-according to Figure 2-the places with possible
local gradients. The changes in EEG will be interesting during the
presence of the EMF emitted by a cell phone. This is, however, a
difficult engineering task. The traditional electroencephalogaphs
properly function because of too much noise, and the signal
filtration is not a successful method suitable for elimination of
induced by EMFs from cell phones. Nevertheless, the telemetric-
Fig2. The map of the EMFS generated
by a cellular phone, synthesized by 'CST Microwave studio' program
(published by authority of 'Electron Trade' company, Russia). (See
Color Plate III at end of issue.)
digital system used in this study allowed us to
record the EEG
signals without interference. Initially, these EMFs cause alpha
the frequency of the main EEG rhythm retains a high
precision, and the signal spectrum changes slightly. If the single
EEG channels were separately analyzed, there is some reliable increase
in the median frequency of spectrum; occasionally, single
sharp waves were also recorded in the areas close to antenna. Most
of these changes were previously reported (see Lebedeva et al.,
2000). Figure 3 illustrates the raw EEG without using our telemetric
system (top: A) and after using our telemetric system (bottom: B).
As seen in Figure 3B, we could record EEG during cell phone
emitting (on) without noise.
Interestingly, the periodical slow wave activities
were also observed
in EEG after turning on the cell phone. Actually, there were
no visible changes in EEG for 10-15 s following turning on the cell
phone (see Figure 3B). After this period, the spectrum for the median
frequency increased in areas close to the antenna. Following
this period (i.e., within 20-40 s) a slow-wave activity appeared
the same areas; as the slow waves appeared, the median frequency
decreased. The slow-wave activity lasted for about 1 s and then
abruptly disappeared. The slow-wave activity exhibiting antiphase
was sometimes observed in the areas contralateral to the antenna
the cell phone. Figure 4 illustrates the slow-wave activity in E7,
and T3 leads (left side); the picture on the right side of Figure
shows the enlarged part of the slow waves with brain mapping.
Interestingly, the frontal areas are activated bilaterally, but
areas are activated contralaterally (red areas: slow waves).
Maximum power spectral density of these waves were within the
range of 2.5-6.0 Hz, at the leads of maximum EMF strength. After
the period of slow-wave activity, the median frequency slightly
and apparently normal EEG was recorded. However, the
slow-wave activity repeated periodically at the same leads every
Figure 5 illustrates the mapping of the slow-wave
activity in relation
to the high frequency EME emitted by the cell phone. As
seen in Figure 5 (right side, three dimensional pictures), the maximum
slow-wave activity (above: red area) coincides with the maximum
field strength. On the left side, the location of the slow-wave
Fig3. EEG in an awake subject
before and after turning on the cell phone (arrows). Notice the
noise in the raw EEG depicted above (A). Below (B), the EEG before
and after (off, on) turning on the cellular phone. Notice the noise-free
recording during using the telemetric registration system (ExpertTM
EEG system, TREDEX Company Ltd., Kharkov, Ukraine).
activity is visualized. Five brain slices (see the skull) are illustrated
consequently, red areas being the most pronounced slow wave activities
in EEG. The red areas show that the EEG changes occur at
the basal regions of the brain. Here, we discovered a total correspondence
of both images (slow waves and EMFs), even taking into
Fig4. Slow-wave activity recorded
at F7, F8, and T3 leads (left); its amplitude and frequency distribution
are shown on the right. Eyes open, awake subject. (See Color Plate
IV at end of issue)
consideration the contralateral areas. The effects of the EMFs emitted
by the cell phone was reversible. That is, the slow waves progressively
disappeared in ten minutes after turning off the cellular
The effects of EMFs on EEG were more pronounced in children
(12 years old). That is, the slow-wave activity appeared earlier
10-15 s after turning on the cell phone) with higher
amplitudes, lasted longer (2-3 s), their frequency was lower (1.0-
2.5 Hz), and they occurred more frequently.
There was no visible change in human EEG after
turning on the cell
phone, except an increase in the median frequency detected only
following spectral analysis. However, after a latent period lasting
for about 15-20 s in adults and 10-15 s in children, a short-lasting
Fig5. Comparison of probabilistic
EEG tomography with the map of a cellular phone's EMFs. Pictures
are from 'Electroencephalograph ExpertTM system' (Tredex Company,
Kharkov, Ukraine). (See Color Plate V at end of issue.)
slow slow-wave activity appeared in EEG. The spectral
indicated that the frequency of the slow waves ranged from 2.5 to
6.0 Hz in adults and from 1.0 to 2.5 Hz in children. Thus, the
periodic delta and theta waves appeared in adults, and only the
waves appeared in children.
The results of the present work clearly showed that the EMFs
emitted by a cell phone affected the human EEG. It is indeed expected
that EMFs in brain leading to afferent electrical signals may
cause subsequent processing events in the brain, like other stimuli
(Marino, 1993; Marino et al., 1996). However, the periodically occurring
slow waves are obviously abnormal for a healthy human
subject, since there are no delta waves in EEG of awake persons.
Interestingly, the slow-wave activity did not disappear even if
cell phone was turned off; the slow waves progressively decreased
in amplitude and then disappeared within tens of min. There are
some animal studies supporting these results. For instance, acute
exposure of rats and rabbits to continuous microwaves increased
EEG delta activity (Shandala et al., 1979). Similarly, Takashima
al. (1979) have reported a decrease in the high frequency EEG bands
and an increase in the low frequency EEG bands. On the other
hand, no uniform changes in EEG power spectra were also reported
following exposure to continuous microwaves (Mitchell et al., 1989).
Increase in delta power was frequently reported
to EMFs in animals (see Hermann & Hossmann, 1997). This
was usually attributed to the thermal effects of EMFs in the brain:
the increase in slow wave activity following exposure to EMFs may
reflect the thermoregulatory response of the brain through the hypothalamus.
The thermoregulatory effect may indeed play a role in the
appearance of the slow-wave activity in the EEG. This is, however,
unlikely for our study, since the delta waves occurred after a latent
period of 15-20 s, lasted only for a few seconds, and occurred
periodically every 15-20 s; they were not continuous. Moreover,
the rise in brain temperature does not exceed 0.01-0.1.C during
exposure to EMFs emitted by cell phones, if blood flow and conduction
is taken into account (Riu & Foster, 1999). Furthermore,
the periodically occurring slow wave activity usually recorded at
the contralateral leads to the antenna of the cellular phone, and
coincided with the strongest EMFs.
There are inconsistent results in the scientific literature concerning
the influence of EMFs emitted by cell phones on the human
EEG. Our results clearly indicate that the cell phones may directly
influence the human brain. This may be a direct influence of the
EMFs on nervous system, since the EMFs were shown to induce
afferent electrical signals like other stimuli within the human
(see Marino et al., 1996). Consistent with our results, it was found
previously that the brain electrical activity changes during exposure
to EMFs (Bell et al., 1992; Lebedeva et al., 2000; Reiser et al.,
1995); inconsistent with our results, it was reported that EEG was
not affected by active cell phones (Hietanen et al., 2000; Roschke
& Mann, 1997). Recently, Croft et al. (2002) have reported that
exposure to acute mobile phone operation altered the resting EEG,
decreasing 1-4 Hz activity, and increasing the 8-12 Hz activity
the midline frontal and lateral posterior responses in the 30-45
band. These authors found alterations in awake EEG, but did not
find any increase in delta wave activity, contrary to our results.
Croft et al. (2002) discussed the possible origins of the inconsistent
results on the effects of mobile phones on the human brain. It is
indeed possible that sitting on a chair for a long time would cause
drowsiness in the subjects, but we required the subjects to keep
their eyes open and keep awake during EEG recordings.
We studied the effects of the EMFs emitted by cellular
the human EEG in adults and children. The EEG was found to show
normal activity during exposure, except a slight increase in the
global median frequency. However, a short-lasting slow-wave activity
occurred after a latent period of 15-20 s after turning on the
phone. We observed these slow-waves, within the delta range, periodically
in every 15-20 s. After turning off the phone, they progressively
decreased in amplitude and disappeared in ten of min. We
have concluded that the EMFs emitted by cell phones may be harmful
for the human brain, since the delta waves are pathological if
seen in awake subjects. On the other hand, the slow wave activity
was more pronounced in children than adults, indicating that the
children may be more vulnerable to the adverse health effects of
mobile phones than adults, probably because absorption of microwaves
is greatest in an object about the size of a child's head (Gandhi
et al., 1996); the radiation can penetrate the thinner skull of
infant with greater ease. We are seriously concerned about possible
risks to human brain from cell phones.
Bell, G. B., Marino, A. A., & Chesson, A. L.
(1992). Alterations in brain electrical activity caused by magnetic
fields: Detecting the detection process. Electroencephalography
and Clinical Neurophysiology, 83, 359-397.
Croft, R. J., Chandler, J. S., Burgess, A. P.,
Barry, R. J., Williams, J. D., & Clarke, A. R. (2002). Acute
mobile phone operation affects neural function in humans. Clinical
Neurophysiology, 113, 1623-1632.
Freude, G., Ullsperger, P., Eggert, S., & Ruppe,
I. (1998). Effects of microwaves emitted by cellular phones on human
slow brain potentials. Bioelectromagnetics, 19, 384-387.
Hietanen, M., Kovala, T., & Hamalainen, A.
M. (2000). Human brain activity during exposure to radiofrequency
fields by cellular phones. Scandinavian Journal of Work and Environmental
Health, 26, 87-92.
Hermann, D. M., & Hossmann, K.-A. (1997). Neurological
effects of microwave exposure related to mobile communication. Journal
of Neurological Sciences, 152, 1-14.
Krause, C. M., Sillanmaki, L., Koivisto, M., Haggqvist,
A., et al., (2000). Effects of electromagnetic fields emitted by
cellular phones on the electroencephalogram during a visual working
memory. International Journal of Radiation Biology, 76, 1659-1667.
Lai, H., Horta, A., Cho, C. K., & Guy, A. W.
(1987). A review of microwave irradiation and actions of psychoactive
drugs. Engineering Medicine and Biology, 6, 31-36.
Lebedeva, N. N., Sulimov, A. V., Suhmova, O. P.,
Kotrovskaya, T. T., & Gailus, T. (2000). Cellular phone electromagnetic
field effects on bioelectric activity of human brain. Critical
Review of Biomedical Engineering, 28, 323-337.
Marino, A. A. (1993). Electromagnetic fields, cancer,
and the theory of neuroendocrinerelated promotion. Bioengineering,
Marino, A. A., Bell, G. B., & Chesson, A. (1996).
Low-level EMFs are transduced like other stimuli. Journal of
the Neurological Sciences, 144, 99-106.
Mitchell, C. L., McRee, D. I., Peterson, N. J.,
Tilson, H. A., Shandala, M. G., Rudnev, M. I., Varetskii, V. V.,
& Navakatikyan, M. I. (1989). Results of a United States and
Soviet Union project on nervous system effects of microwave radiation.
Environmental Health Project, 81, 201-209.
Moulder, J. E., & Foster, K. R. (1995). Biological
effects of power-frequency fields as they relate to carcinogenesis.
Proceedings of the Society for Experimental Biology and Medicine,
Persson, B. R. R., Salford, L. G., & Brun,
A., et al. (1997). Blood-brain barrier permeability in rats exposed
to electromagnetic fields used in wireless communication. Wireless
Networks, 3, 455-461.
Reiser, H.-P., Dimpfel, W., & Schober, F. (1995).
The influence of electromagnetic fields on human brain activity.
Eur J Med Res, 1, 27-32.
Repacholi, M. H. (1997). Radiofrequency field
exposure and cancer what do the laboratory studies suggest? Environmental
Health Perspectives, 105, Suppl. 6, 1565-1568.
Repacholi, M. H., Basten, A., Gebski, V., Noonan,
D., Finnie, J., & Harris, A. W. (1997).
Lymphomas in E mu-Piml transgenic mice exposed to pulsed 900 MHz
fields. Radiation Research, 147, 631-640.
Riu, P. J., & Foster, K. R. (1999). Heating
of tissue by near-field exposure to a dipole: A model analysis.
IEEE Transactions on Biomedical Engineering, 46, 911-917.
Roschke, J., & Mann, K. (1997). No short term
effects of digital mobile radio telephone on the awake human electroencephalogram.
Bioelectromagnetics, 18, 172-176.
Shandala, M. G., Dumanski, U. D., Rudnev, M. I.,
Ershova, L. K., & Los, L. P. (1979). Study of nonionizing microwave
radiation effects upon the central nervous system and behaviour
reaction. Environmental Health Perspectives, 30, 115-121.
Sidorenko, A. V., & Tsaryk, V. V. (1999). Electrophysiological
characteristics of the epileptic activity in the rat brain upon
microwave treatment. In Proceedings of conference on electromagnetic
fields and human health (pp. 283-284). Moscow.
Takashima, S., Onaral, B., & Schwan, H. P.
(1979). Effects of modulated RF energy on the EEG of mammalian brain.
Radiation and Environmental Biophysics, 16, 15-27.
Youbicier-Simo, B. J., & Bastide, M. (1999).
Pathological effects induced by embryonic and postnatal exposure
to EMFs radiation by cellular mobile phones (written evidence to
IEGMP). Radiation Protection, 1, 218-223.