A recent issue of the journal published 2 papers on the subject
of cell phone safety, as well as an accompanying editorial. The
editorial, written by Philip P. Dendy of Cambridge, UK, and entitled
"Mobile phones and the illusory pursuit of safety" puts
the 'safety' issue into perspective:
Dr. Hyland writes an excellent paper, covering the possible mechanisms
by which mobile phones, or cell phones, may cause adverse effects
in people. Below are some exerpts from his paper, entitled "Physics
and Biology of Mobile Telephony":
... 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. ... 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.
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 ... .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 detectable heating (3).
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.
Physics of Mobile Telephony
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
localized 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 µW/cm (2).
A handset that is in operation also has a low-frequency magnetic
field (EMF) 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. 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 behavioral and physiological
disorders can be provoked by temperature rises below 1°C --
ie, under much less acute exposure conditions ... there are reports
of adverse health effects of subthermal intensities, the possible
origin of which will now be considered.
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 underpinned
(6) 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 a radio.
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 834 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 aircraft (11) and hospitals (a prohibition driven by concerns
about non-thermal interference) seems inconsistent.
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 same
radiation.
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.
Panel 1: Selected in vitro studies
of non-thermal effects of microwave radiation of various frequencies
and intensities
| Effect |
Reference |
| Epileptic activity in rat brain slices in conjunction with
certain drugs |
13 |
| Resonant effects on cell division of Saccharomyces cerevisiae,
and on the genome conformation of Escherichia coli |
9, 14 |
| Synchronisation of cell division in S carlsbergenis |
15 |
| "Switch-on" of epigenetic processes, such as -phage
and colicin synthesis |
16, 17 |
| Altered ornithine decarboxylase activity |
18 |
| Reduced lymphocyte cytotoxicity |
19 |
| Increased permeability of erythrocyte membrane |
20 |
| Effects on brain electrochemistry (calcium efflux) |
21 |
| Increase in chromosome aberrations and micronuclei in human
blood lymphocytes |
22 |
| Synergism with cancer-promoting drugs such as phorbol ester
|
23 |
In vivo evidence of non-thermal influences, including exposure
to actual GSM radiation, comes predominantly from animal studies
(panel 2).
Panel 2: Selected in vivo studies of
non-thermal microwave exposure, including GSM radiation
| Effect |
Reference |
| Epileptiform activity in rats, in conjunction with certain
drugs |
24 |
| Depression of chicken immune systems (melatonin, corticosterone
and IgG levels) |
25 |
| Increase in chick embryo mortality |
25 |
| Increased permeability of blood-brain barrier in rats |
26 |
| Effects on brain electrochemistry (dopamine, opiates) |
27 |
| Increases in DNA single and double strand breaks in rat
brain |
28 |
| Promotion of lymphomas in transgenic mice |
29 |
| Synergistic effects with certain psychoactive drugs |
30 |
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 corroborated (31) 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 brain (34) and affects memory tasks (35). In 1998, Braune
et al (36) recorded increases in resting blood pressure during
exposure to radiofrequencies.
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.
Possible Associated Adverse Health Reactions
... 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 levels (25) and
- on rapid-eye-movement sleep (32).
Furthermore, since there is no reason to suppose that the seizure-inducing
ability (12) 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.
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 study (42) is consistent not only
with the genotoxicity of GSM radiation, as indicated by increased
DNA strand breaks (28) and formation of chromosome aberrations
and micronuclei but also with its promotional effect on tumour
development (43).
... 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 parliamentary committee (44).
Preadolescent children can be expected to be more vulnerable
to any adverse health effects than adults because absorption of
GSM microwaves is greatest (5) 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 infant (1).
Also the multiframe repetition frequency of 834 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 degraded
(19,25) 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).
The references to this excellent review by Dr. Hyland are given
below.
In a separate Lancet report, Massachusetts scientist Dr. Kenneth
Rothman said his research indicated the main public health concern
was motor vehicle collisions rather than any possible link to brain
cancer.
In addition, use of 'hands-free' units was no less risky than holding
the telephone to the ear with one hand while talking.
Many people concerned with possible adverse health effects, including
myself, have recommended the use of "Hands Free" units
as a way to greatly reduce the microwave exposure. However, as we
reported several weeks ago this may not necessarily be any safer.
Now, upon further review of the safety evidence, including the
results of tests conducted by the British Consumers Association
and published in their magazine Which?
the British government has decided to withdraw its recommendation
that mobile phone users switch to handsfree units.
In addition, they plan to start issuing leaflets warning buyers
of the unknown, but potentially harmful impact of mobile phone usage
by children, according to a report in Newsbytes.com.
The warnings follow the British government's continuing funding
of tests into the effects of mobile phone radio frequency (RF) radiation
on the soft tissue of the brain and head.
Liam Donaldson, the UK's chief medical officer, said that the government's
decision to remove the health approval on handsfree kits followed
a number of investigations that claim handsfree devices may even
channel radiation to the users head. "We don't have good enough
science so far to say definitely one way or the other," he
said, adding that further research is being conducted urgently to
provide an answer to the question.
