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Cell Phone Radiation
The safety of cell phones is in doubt again, as a new study suggests a link
with brain cancer.
Concerns have been raised once again that cell phones might be linked to brain
and head cancers and, once again, an entirely satisfactory assessment of the
dangers, if any, remains frustratingly elusive.
The health effects of cell phones are far from obvious, so the risks cannot be
large. But that does not mean they must be insignificant: with more than 44
million cellphones used in Britain and approaching one billion worldwide, even a
small risk would have devastating ramifications.
This month, during a debate at the British Association's science festival in
Glasgow, an important new study was cited. Probably its most significant
conclusion is a dose response relationship that links the duration of phone use
and tumour risk. The study found that use of cell phones for up to 10 years
increased the risk of brain cancer by 26 per cent, but the risk jumped to 77 per
cent for more than a decade's use.
The tumours were significantly more likely to be on the side of the head where
the cell phone was held - 2.5 times greater for temporal brain tumours and 3.7
times greater for acoustic neurinoma tumours, which involves the auditory nerve
and begins in the ear canal. Although benign, the latter tumours can cause
facial paralysis and become life-threatening if they exert too much pressure
inside the skull.
Although several previous studies have suggested that cell phones might have
detrimental effects, this study shifts the balance of evidence, challenging the
conclusions of a major inquiry that was published last year.
The radiation watchdog, the National Radiological Protection Board (NRPB), said
it will not comment until this work is published in a peer-reviewed journal. But
the study has already gained credence because of the size of its sample (1,617
cancer patients and a control of the same number) and its duration (more than a
decade of epidemiological data).
The good news, if such, was that the epidemiological data used applied to
analogue cell phones, which were phased out in 1997. The bad news was that
although the digital GSM system currently in use emits less radiation, its
pulsed nature might make it more damaging.
"We will have to wait several more years, probably at least until 2005, before
we can see the health effects of digital phones," said Lennart Hardell, author
of the study and professor of oncology at Orebro University in Sweden. In the
meantime, he added, users should exercise caution.
The findings fuelled the row over the use of cell phones by children. It grew in
intensity at the science festival debate when Sir William Stewart, president of
the Royal Society of Edinburgh and chairman of the Government's independent
expert group on cell phones, condemned cell phone companies for encouraging
young people to use them.
For parents worried by the the gadget their children clutch to their ears, often
for hours at a time, it was the latest in a long line of inconclusive and
contrary reports. Driven by the rising tide of parental concerns and cranks
peddling bogus science on microwave radiation, the Department of Health set up
an inquiry in 1999.
Sir William's expert group on cell phones concluded in May last year that the
balance of evidence then available did not suggest that emissions from handsets
or masts put the health of the general population at risk - a finding broadly
echoed by the health directorate in France, among others. But still the issue
was not settled. Sir William made recommendations that suggested the jury was
still out. There was scientific evidence suggesting the kind of microwave
radiation that cell phones emit might have biological effects, even at exposures
below NRPB guidelines. And he said the effects could be beneficial or adverse.
"We recommend that a precautionary approach to the use of cell phone
technologies be adopted until much more detailed and scientifically robust
information on any health effects becomes available," Sir William advised.
In particular, he recommended that children, whose skull bones are less
developed than adults and who will probably use cell phones for more of their
lifetimes, should not use cellphones more than necessary.
The expert group also suggested the guidelines of the International Commission
on Non-Ionising Radiation Protection on exposure to radiation should be adopted
in Britain (although no detailed scientific evidence was provided to justify the
commission's recommendation that maximum exposure levels for the public should
be about five times lower than the NRPB guidelines). Crucially, Sir William said
that guidelines are set to minimise tissue heating and take no account of
so-called non-thermal effects.
Since then, a new research programme costing pounds 7.5 million has been
commissioned, half of it sponsored by the industry and half by the Department of
Health, which will be reviewed by a panel under Sir William's chairmanship.
Funding is only now being allocated.
There have also been delays in responding to the Stewart report. He recommended
that the specific absorption rate of the radio waves given out by phones should
be displayed on their packaging, so people can select the lowest values (these
can vary by up to 50 times between models). It is yet to happen, though the
industry promises labelling will start next month.
Sir William has also been concerned by a pounds 2.5 billion secure radio system
- the Terrestrial Trunked Radio (Tetra) digital radio system - already under
test by police in Lancashire, which looks likely to be adopted by the emergency
services and the Ministry of Defence.
The system is modulated at close to 16 pulses a second (Hz), a frequency his
report said should be avoided as a precaution because old research seemed to
suggest it might affect the release of calcium from brain tissue. Neurons are
sensitive to calcium, which carries out signalling, regulates secretions and
other tasks, though the Stewart report said there was as yet no evidence of what
consequences this had for health.
Little work has been conducted on the calcium effect since the early Eighties,
although a recent study on rats reported to the Bioelectromagnetics Society by
Dr John Tattersall of the Defence science and technology laboratory failed to
show any unusual effect from one type of 16Hz modulation on brain cell function.
However, another study by Dr Tattersall, published a few weeks ago in the
journal Brain Research, showed that radio frequency radiation can affect brain
cell signalling at intensities well below those that cause heating. "We don't
know what this means at the moment," Dr Tattersall said. "The effects we have
found could be hazardous - they could even be beneficial."
A Tetra report for the NRPB was mostly reassuring, though it did call, among
other things, for studies of the calcium effect, research on volunteers, and
efforts to see if there is a link with epileptic fits. Co-author Prof Colin
Blakemore of Oxford University said that, in some circumstances, Tetra could
breach existing NRPB safety guidelines and added that Dr Tattersall's Brain
Research study meant that a new effect on brain cells of low-level radio waves
has been discovered.
"This is the first direct evidence I know of that very low-intensity radio
frequency radiation can directly affect the potential difference [voltage]
across nerve membranes," Prof Blakemore said. "There does seem to be something
going on.
"Personally, I am not worried, but this is the best-documented example of a
non-thermal effect on nerve cells This issue needs to be pinned down once and
for all by additional research."
Like cell phones, Tetra seems destined to be a victim of the adage that it is
impossible to prove safety. Unless incontrovertible hard evidence of a health
risk emerges, we will have to continue to wonder about the health effects of our
love affair with the cell telephone.
Risks remain elusive
The reason for the confusion about cell phone health effects is easy to see,
given the contradictory findings. In many cases, the studies have either not
been replicated or replication has failed to confirm the effects.
No problem
A four-year case-control study published last December in the Journal of the
American Medical Association reported no association between cellphone use and
brain cancer risk. Joshua Muscat, who led the study, was concerned about one
sub-group of patients with a rare type of slow-growing tumour and wanted to
conduct further studies.
A study by the National Cancer Institute, published last spring in the New
England Journal of Medicine, found no association between cellphone users and
certain types of brain tumours.
There is no correlation between phone use and brain or nervous system cancers,
according to a study of 420,000 Danish cell phone users conducted by the Danish
Cancer Society and published in the Journal of the National Cancer Institute
this year.
The jury's out
A study by Dr Alan Preece of Bristol University found reaction times speeded up
among cell phone users. These findings, replicated and confirmed by another
study published last year, indicate a biological effect of microwave radiation,
most likely caused by tissue warming.
Researchers at the University Neurology Clinic in Freiburg, Germany, found cell
phones increased blood pressure. The rise was small but could be harmful to
people with high pressure levels, they said.
An expert panel report prepared under the direction of the Royal Society of
Canada could find no conclusive evidence of adverse health effects from radio
frequency exposure. However, like the Stewart report, it recognised that
documented biological effects existed at even low levels, that those effects
might have adverse health effects and called for more research.
A study of 11,000 cell phone users conducted by Dr Kjell-Hansson Mild at the
National Institute of Working Life in Umea, Sweden, suggested that regular use
of cells phones could lead to fatigue, headaches and skin irritation.
Scientists led by David de Pomerai at the University of Nottingham found that
tiny nematode worms grow faster but wriggle less when given a dose of
low-intensity microwaves.
Henry Lai at the University of Washington in Seattle found rats exposed to
microwaves produce endorphins and were more likely to binge on alcohol or react
strongly to morphine and barbiturates.
Smoking gun
An 18-month study Dr Ray Tice and Dr Graham Hook of Integrated Laboratory
Systems in North Carolina examined the genetic effects of cell phone frequency
fields. Although they found no evidence of chromosome damage, a test on
micronuclei in human blood cells showed a biological effect. When human blood in
a test tube was exposed to cell phone radiation for 24 hours, there was an
eightfold increase in micronuclei cells. Some scientists believe there is a
direct link between the presence of micronuclei and cancer.
In 1994, Dr Leif Salford showed a breakdown in the blood-brain barrier of rats
when they were exposed to radio waves, possibly impairing the blood-brain
barrier's ability to protect the brain.
A team at the University of Essen in Germany concluded that people who regularly
used a cell phone were three times more likely to develop cancer of the eye.
Daily Telegraph
By: Robert Uhlig & Roger Highfield
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