Physics and Biology of Mobile Telephony
originally appearing in The
Lancet - Vol. 356, Issue 9244, 25 November
2000, Pages 1833-1836
by G. J. Hyland, PhD
Department of Physics International Institute of Biophysics, University of Warwick,
International Institute of Biophysics,
Although safety guidelines--to which mobile telephones and their
base-stations conform -- do protect against excessive microwave heating, there is evidence that the low
intensity, pulsed radiation currently used can exert subtle non-thermal influences. If these influences
entail adverse health consequences, current guidelines would be inadequate. This review will focus on this
possibility. The radiation used is indeed of very low intensity, but an oscillatory similitude between
this pulsed microwave radiation and certain electrochemical activities of the living human being should prompt
concern. However, being so inherently dependent on aliveness, non-thermal effects cannot be expected to be
as robust as thermal ones, as is indeed found; nor can everyone be expected to be affected in the same way by
exposure to the same radiation. Notwithstanding uncertainty about whether the non-thermal influences reported do
adversely affect health, there are consistencies between some of these effects and the neurological problems
reported by some mobile-telephone users and people exposed longterm to base-station radiation. These
should be pointers for future research.
Public concern over possible adverse health impacts from exposure to
the radiation used in GSM (Global System for Mobile communication) mobile telephony shows little sign of
abating, despite assurances from the industry and official bodies such as the UK National Radiological
Protection Board (NRPB) that all is well. In March, 1999, the UK Government set up the Independent Expert
Group on Mobile Phones, under the chairmanship of Sir William Stewart. The Stewart Report,1
published in May, 2000, makes some sensible recommendations, but unfortunately some of its greyer areas are now
being exploited by the industry to obfuscate the issue. As yet unresolved is the question of adverse
health impacts provoked by the contentious non-thermal effects of the low intensity, pulsed microwave radiation
(MWR) used. For these effects are not taken into account in current safety guidelines,2
which simply restrict the intensity of the radiation to prevent tissue heating in excess of what the body's
thermoregulatory mechanism can cope with. Whilst these guidelines, which are the result of careful
investigation over many years, are clearly necessary, the question remains as to whether they are comprehensive
enough. For in the case of living systems (and only living ones) there are many reports over the past 30
years that MWR can exert non-thermal influences, at intensities well below those necessary to cause any
The purpose of this review is to introduce clinicians to the physics
of mobile telephony and to explain how low-intensity, pulsed microwaves can affect living organisms, both
thermally and non-thermally; and then to identify some of the reported biological impacts of exposure to this
radiation, particularly those provoked by the contentious non-thermal effects. It is thereby hoped to
alert clinicians to the possibility that certain presenting symptoms might well be a consequence of non-thermal
exposure to this kind of radiation. A companion Lancet review4 covers the
epidemiological evidence for effects of mobile telephony on human health.
Physics of mobile telephony
Mobile (cellular) telephony is based on two-way radio communication
between a portable handset and the nearest base-station. Every base-station serves a cell, varying from
hundreds of metres in extent in densely populated areas to kilometres in rural areas, and is connected both to
the conventional land-line telephone network and, by tightly focused line-of-sight microwave links, to
neighbouring stations. As the user of a mobile phone moves from cell to cell, the call is transferred
between base-stations without interruption.
The radio communication utilises microwaves at 900 or 1800 MHz to
carry voice information via small modulations of the wave's frequency. A base-station antenna typically
radiates 60 W and a handset between 1 and 2 W (peak). The antenna of a handset radiates equally in all
directions but a base-station produces a beam that is much more directional. In addition, the stations
have subsidiary beams called side-lobes, into which a small fraction of the emitted power is channelled.
Unlike the mean beam, these side-lobes are localised in the immediate vicinity of the mast, and, despite their
low power, the power density can be comparable with that of the main beam much further away from the mast.
At 150-200 m, for example, the power density in the main beam near ground level is typically tenths of a
A handset that is in operation also has a low-frequency magnetic
field associated, not with the emitted microwaves, but with surges of electric current from the battery that are
necessary to implement "time division multiple access" (TDMA), the system currently used to increase
the number of people who can simultaneously communicate with a base-station. Every communication channel
has eight time slots (thus the average power of a handset is 1/8 of the peak values cited above -- ie, is
between 0·125 W and 0·25 W), which are transmitted as 576 µs bursts. Together, the eight slots define a
frame, the repetition rate of which is 217 Hz. The frames transmitted by both handsets and base-stations
are grouped into "multi-frames" of 25 by the absence of every 26th frame. This results in an
additional low-frequency pulsing of the signal at 8·34 Hz, which, unlike that at 217 Hz, is unaffected by call
density, and is thus a permanent feature of the emission. With handsets that have an energy-saving
discontinuous transmission mode (DTX), there is an even lower frequency pulsing at 2 Hz, which occurs when the
user is listening but not speaking.
Biological impacts: thermal
Heating of biological tissue is a consequence of microwave energy
absorption by the tissue's water content. The amount of heating produced in a living organism depends
primarily on the intensity (or power density) of the radiation once it has penetrated the system, on certain
electrical properties of the biomatter, and on the efficiency of the body's thermoregulation mechanism.
Above a certain intensity of the microwaves, temperature homoeostasis is not maintained, and effects on health
ensue once the temperature rise exceeds about 1°C. Safety guidelines impose upper limits on the radiation
intensity to ensure that this does not happen. Heating occurs whether the organism is alive or dead.
The frequency of the radiation, as opposed to the intensity, is taken into account only in so far as it affects
(via size resonance) the ability of the organism to absorb energy from the irradiating field.
Amongst the most thermally vulnerable areas of the body,2
because of their low blood supply, are the eyes and the testes, and cataract formation and reduced sperm counts
are well-documented acute exposure hazards. Animal studies indicate that a variety of behavioural and
physiological disorders can be provoked by temperature rises below 1°C -- ie, under much less acute exposure
There have been many investigations to estimate, using phantom
heads,5 the rate at which thermal energy is deposited in the head during use of a mobile phone
-- the so-called absorption rate. These studies indicate that, for most handsets, safety guidelines are
not violated. In publicly accessible areas near a base-station, thermal influences of the emitted MWR can
be totally discounted; the microwave intensity is far too low. Nevertheless, in both cases there are
reports of adverse health effects of subthermal intensities, the possible origin of which will now be
Biological effects: non-thermal
The possibility that the pulsed, low-intensity MWR currently used in
GSM mobile telephony can exert subtle, non-thermal influences on a living organism arises because microwaves are
waves; they have properties other than the intensity that is regulated by safety guidelines. This
microwave radiation has certain well-defined frequencies, which facilitate its discernment by a living organism
(despite its ultralow intensity), and via which the organism can, in turn, be affected. The human body is
an electrochemical instrument of exquisite sensitivity whose orderly functioning and control are underpinned6
by oscillatory electrical processes of various kinds, each characterised by a specific frequency, some of which
happen to be close to those used in GSM. Thus some endogenous biological electrical activities can be
interfered with via oscillatory aspects of the incoming radiation, in much the same way as can the reception on
The biological electrical activities that are vulnerable to
interference from GSM radiation include highly organised electrical activities at a cellular level whose
frequency happens to lie in the microwave region, and which are a consequence of metabolism.7
Although not universally accepted, there is experimental evidence7-9 consistent with these
endogenous activities, in terms of which effects of ultralow-intensity microwave radiation of a specific
frequency on processes as fundamental as cell division, for example, can be understood in a rather natural way.10
Furthermore, the DTX pulse frequency at 2 Hz and the TDMA frequency of 8·34 Hz correspond to frequencies of
electrical oscillations found in the human brain, specifically the delta and alpha brain-waves,
respectively. It is thus quite possible that living organisms have a two-fold sensitivity to the pulsed
GSM signal -- ie, to both the microwave carrier and the lower frequency pulsings of the TDMA and DTX
signals. To deny this possibility yet admit the importance of ensuring electromagnetic compatibility with
electronic instruments by banning the use of mobile phones on aircraft11 and hospitals (a
prohibition driven by concerns about non-thermal interference) seems inconsistent.
Thus, in contrast to heating, which relies on an organism's ability
to absorb energy from the irradiating field, the possibility of non-thermal effects arises from an
"oscillatory similitude" between the radiation and the living organism, which makes it possible for
the living organism to respond to low-intensity, pulsed MWR via its ability to recognise certain frequency
characteristics of that radiation. The intensity of radiation needed for this recognition is many orders
of magnitude below even that currently associated with non-thermal effects. This influence is possible
only when the organism is alive, with excited endogenous frequencies; the dead have flat
electroencephalograms. Non-thermal effects thus depend on the state of the person when exposed to the
radiation--ie, non-thermal effects are non-linear. A low-intensity field can entail a seemingly
disproportionately large response (or none at all), and vice versa, quite unlike the predictable thermal
responses. Thus not everyone can be expected to be affected in the same way by identical exposure to the
A good example of human vulnerability to a non-thermal,
electromagnetic influence is the ability of a light flashing at about 15 Hz to induce seizures in people with
photosensitive epilepsy.12 It is not so much the amount of energy absorbed from the
light that provokes the seizure, but rather the information transmitted to the brain by the (coherent)
regularity of its flashing, at a frequency that the brain "recognises" because it matches or is close
to a frequency utilised by the brain itself.
What do we know experimentally about non-thermal biological
influences of MWR (both pulsed and continuous) of an intensity close to that near a mobile phone handset, but
often at higher microwave carrier frequencies? A selection of in vitro studies is given in Panel 1.
in vitro studies of non-thermal effects of microwave radiation of various frequencies and intensities.
In vivo evidence of non-thermal influences, including exposure to
actual GSM radiation, comes predominantly from animal studies (panel 2). Finally, human in vivo studies,
under GSM or similar conditions, include effects on the EEG and on blood pressure. A delayed increase in
spectral power density (particularly in the alpha band) has been corroborated31 in the "awake" EEG of
adults exposed to GSM radiation. Influences on the "alseep" EEG include a shortening of
rapid-eye-movement (REM) sleep during which the power density in the alpha band increases,32
and effects on non-REM sleep.33 Exposure to mobile phone radiation also decreases the
preparatory slow potentials in certain regions of the brain34 and affects memory tasks.35
In 1998, Braune et al36 recorded increases in resting blood pressure during exposure to
Selected in vivo studies of non-thermal microwave exposure,
including GSM radiation.
Although the power density of the radiation used in these
experiments is typical of that found at the head when a mobile handset is used, and thus much higher than that
close to a base-station, the information content of the radiation emitted by base-stations is the same.
Accordingly -- apart from near/far field differences (ie, localised exposure to the near field during handset
use and whole body exposure to the far field from a base-station) -- these results are not irrelevant to any
consideration of potential adverse health effects associated with chronic exposure to base-station radiation.
Non-thermal effects have proved controversial, and independent
attempts to replicate them have not always been successful. Such difficulties are not unexpected, however,
because these effects depend on the state of the organism when it is exposed, particularly in vivo. In in
vitro studies, discrepant findings can sometimes be traced to differences in the conditions or design of the
experiment. Examples of this are the unsuccessful attempts to replicate an earlier yeast-growth
experiment,37,9 and the reported increased incidence of DNA strand breaks.38,28
The highly non-linear nature of living systems makes them hypersensitive (via deterministic chaos,39
as exemplified by the so-called "butterfly effect", for example) to the prevailing conditions, and
thus militates against the realisation of the identical conditions necessary for exact replication.
Possible associated adverse health reactions
It is important to stress that the existence even of established
non-thermal effects does not make adverse health consequences inevitable. Nonetheless GSM radiation does
seem to affect non-thermally a variety of brain functions (including the neuroendocrine system), and health
problems reported anecdotally do tend to be neurological, although formal confirmation of such reports, based on
epidemiological studies, is still lacking. For example, reports of headache are consistent with the effect
of the radiation on the dopamine-opiate system of the brain27 and the permeability of the
blood-brain barrier,26 both of which have been connected to headache.40,41
Reports of sleep disruption are consistent with effects of the radiation on melatonin levels25
and on rapid-eye-movement sleep.32 Furthermore, since there is no reason to suppose that
the seizure-inducing ability12 of a flashing visible light does not extend to microwave
radiation (which can access the brain through the skull) flashing at a similarly low frequency, together with
the fact that exposure to pulsed MWR can induce epileptic activity in rats,24 reports of
epileptic activity in some children exposed to base-station radiation are perhaps not surprising. I have
heard of one child whose seizures diminish when, unbeknown to her or her family, the mast is not functioning (or
when she is away), only to increase again when the base-station is working again or when she returns home.
Finally, the significant increase (by a factor of between 2 and 3)
in the incidence of neuroepithelial tumours (the laterality of which correlates with cell-phone use) found in a
nationwide US study42 is consistent not only with the genotoxicity of GSM radiation, as
indicated by increased DNA strand breaks28 and formation of chromosome aberrations and
micronuclei but also with its promotional effect on tumour development.43 However, as
Rothman's accompanying review shows,4 the overall epidemiological evidence for an association
with cell-phone use is rather weak. Nevertheless, it cannot be denied that non-thermal effects of the MWR
used in mobile telephony do have the potential to induce adverse health reactions of the kind reported, and this
possibility should not be ignored even if only a small minority of people are at risk. Whether a person is
affected or not could depend, for example, on the level of stress before exposure; if it is high enough, the
additional contribution from MWR exposure might be sufficient to trigger an abnormality that would otherwise
have remained latent. It is often argued that anecdotal reports of health problems should be
dismissed. However, given the paucity of systematic epidemiological studies of this new technology, such
reports are an indispensable source of information, a point acknowledged in the 1999 report of the UK
Preadolescent children can be expected to be more vulnerable to any
adverse health effects than adults because absorption of GSM microwaves is greatest5 in an object about the size
of a child's head, because of the "head resonance" effect and the greater ease with which the
radiation can penetrate the thinner skull of an infant1. Also the multiframe repetition
frequency of 8·34 Hz and the 2 Hz pulsing in the DTX mode of cellphones lie in the range of the alpha and delta
brain-waves, respectively. In a child, alpha waves do not replace delta waves as a stable activity until the age
of about 12 years. Furthermore, the immune system, whose efficacy is degraded19,25 by
this kind of radiation, is less robust in children. This makes them less able to cope with any adverse
health effect that might be provoked by chronic exposure, not only to the pulsed microwave radiation but also to
the the more penetrating low-frequency magnetic fields associated with the current surges from the handset
battery which can reach 40 µT (peak) near the back of the case.45 Indications of the
biological noxiousness of these magnetic fields (in animals) can be found in ref 25.
In the context of base-station radiation, reports relating to
animals are of particular value since it cannot here be claimed that the effects are psychosomatic. Of
particular interest is a publication on cattle,43 recording severely reduced milk yields,
emaciation, spontaneous abortions, and stillbirths. When cattle are removed to pastures well away from the
mast, their condition improves, but it deteriorates once they are brought back. The adverse effects
appeared only after GSM microwave antennae were installed on a tower formerly used to transmit only non-pulsed
television and radio signals.
Finally, in support of the reality of an adverse health impact of
non-thermal influences of the kind of radiation used today in mobile telephony, we should recall that during the
"cold war" the Soviet irradiation of western embassies with microwave radiation (of an intensity
intermediate between that in the vicinity of a handset and a base-station), done with the express intention of
inducing adverse health effects, was quite successful.47
|G J Hyland, PhD
phones and health. London: Stationery
Guidelines for limiting exposure
to time varying electric, magnetic and electromagnetic fields (up to 300 GHz). Health
Phys 1998; 74: 494-522.
advisory system: mobile phones and health vol II, appendix 15: 86–91. London: Stationery
evidence on health risks of cellular telephones. Lancet 2000; 356: 1837-1840.
Text | Full-Text
PDF (75 KB) | MEDLINE
absorption in the human head and neck for mobile telephones at 835 and 1900 MHz. IEEE
Trans MTT 1996; 44: 1884-1897.
man. London: Dent
& Sons, 1989:.
biological effects of microwaves and related questions. Adv
Electronics Electron Phys 1980; 53: 85-152.
8. In: ,
Fröhlich H, ed. Biological coherence and response to external
stimuli. Berlin: Springer-Verlag, 1988:.
Experimental evidence for coherent excitations
correlated with cell growth. Nanobiology 1992; 1: 163-176.
bioeffects induced by low intensity microwave irradiation of living systems. Engineering
Sci Educ J 1998; 7: 261-269.
signals: now it's official: avionics and mobile phones do not mix. New
Sci 2000; 166: 7.
epilepsy. London: MacKeith
Tattersall J. New Horizons 1999 (autumn): 11.
rearrangement in the spectrum of resonance effect of millimetre waves on the genome conformational state of Escherichia
coli cells. Electro-Magnetobiol 1997; 16: 69-82.
of EHF radiation polarization on yeast cells. Radiophys
Quantum Electron 1994; 37: 82-84.
Switching of prophage $gM genes in E
coli by millimetre waves. Med
Sci Res 1990; 18: 955-957.
Effects of millimetre-band electromagnetic
radiation on the functional activity of certain genetic elements of bacterial cells. Sov
Phys Usp (English transl) 1974; 16: 571-572.
of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells. Bioelectromagnetics 1997; 18: 132-141.
Suppression of T-lymphocyte cytotoxicity following
exposure to sinusoidally amplitude-modified fields. Bioelectromagnetics 1983; 4: 281-292.
damage of human red blood cells induced by low power microwave radiation. Electro-Magnetobiol 1995; 14: 99-105.
radiation-induced calcium ion efflux from human neuroblastoma cells in culture. Bioelectromagnetics 1984; 5: 71-78.
The correlation between the
frequency of micronuclei and specific aberrations in human lymphocytes exposed to microwave radiation in
Res 1992; 281: 181-186.
Neoplastic transformation of C3H/10T1/2 cells
following exposure to 120 Hz modulated 2.45 GHz microwaves and phorbol ester tumour promoter. Radiation
Res 1991; 126: 65-72.
Sidorenko AV, Tsaryk VV. Electrophysiological characteristics of the
epileptic activity in the rat brain upon microwave treatment. In: Proceedings of Conference on
Electromagnetic Fields and Human Health (Moscow, September, 1999): 283–84.
Pathological effects induced by embryonic and
postnatal exposure to EMFs radiation by cellular mobile phones (written evidence to IEGMP). Radiat
Protect 1999; 1: 218-223.
permeability in rats exposed to electromagnetic fields used in wireless communication. Wireless
Networks 1997; 3: 455-461.
27. In: ,
Frey AH, ed. On the nature of electromagnetic field interactions
with biological systems. Austin,
TX: RG Landes, 1994:.
Single and double-strand DNA breaks after acute
exposure to radiofrequency radiation. Int
J Radiation Biol 1996; 69: 13-521.
in EJ-Pim 1 transgenic mice exposed to pulsed 900 MHz electromagentic fields. Radiation
Res 1997; 147: 631-640.
A review of microwave
irradiation and actions of psychoactive drugs. Engineering
Med Biol 1987; 6: 31-36.
The influence of electromagnetic
fields on human brain activity. Eur
J Med Res 1995; 1: 27-32.
Effects of pulsed high-frequency electromagnetic
fields on human sleep. Neuropsychobiology 1996; 33: 41-47.
electromagnetic field affects human sleep and sleep electroencephalogram. Neurosci
Lett 1999; 275: 207-210.
microwaves emitted by cellular phones on human slow brain potentials. Bioelectromagnetics 1998; 19: 384-387.
Effects of electromagnetic field emitted by cellular
telephones on the EEG during a memory task. NeuroReport 2000; 11: 761-764.
blood pressure increase during exposure to radio-frequency electromagnetic field. Lancet 1998; 351: 1857-1858.
Text | Full-Text
PDF (57 KB) | MEDLINE
frequency fields at low power density do not affect the division of exponential phase Saccharomyces
cerevisiae cells. Bioelectromagnetics 1997; 18: 142-155.
DNA damage in rat brain
cells after in vivo exposure to 2450 MHz electromagnetic radiation and various methods of euthanasia. Radiation
Res 1998; 149: 637-645.
role of chaos in biological systems In: Barrett TW,
Pohl HA, eds. Energy transfer dynamics. Berlin: Springer-Verlag, 1987: 224-236.
of blood-brain barrier function by serotonin induces desynchronization of spontaneous cerebral cortical
activity: experimental observations in the anaesthetized rat. Neuroscience 1995; 68: 1097-1104.
Increased density of
dopamine D5 receptor in peripheral blood lymphocytes of migraineurs: a marker of migraine?. Neurosci
Lett 1996; 207: 73-76.
Carlo GL. Wireless telephones and health: WTR Final Report. Presented to the
French National Assembly, June 19, 2000.
in E mu-Piml transgenic mice exposed to pulsed 900 MHz electromagnetic fields. Radiat
Res 1997; 147: 631-640.
Scientific Advisory System: mobile phones and health. London: Stationery
Office 1999: vol 1, para 36.
The technology of mobile telephone systems
relevant for risk assessment. Radiat
Prot Dosim 1997; 72: 249-257.
evidence of radiofrequency radiation (microwave) effects on health in military, broadcasting, and
occupational studies. Int
J Occup Environ Health 1995; 1: 47-57.
Conspicuous behavioural abnormalities in a dairy cow
herd near a TV and radio transmitting antenna. Pract
Vet Surg 1998; 79: 437-444.
to: Dr G J Hyland, Department of Physics, University of Warwick, Coventry CV4 4AL, UK
of Physics, University of Warwick, Coventry, UK;
International Institute of Biophysics, Neuss-Holzheim, Germany