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U.S. FDA
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left page (136)
of SP65 FUG am, A31008-H7450-A40-1-4A19 (15.02.2005, 15:47)
How much evidence is there that hand-
held mobile phones might be harmful?
Briefly, there is not enough evidence
to know for sure, either way; howev-
er, research efforts are on-going.
The existing scientific evidence is
conflicting and many of the studies
that have been done to date have
suffered from flaws in their research
methods. Animal experiments inves-
tigating the effects of RF exposures
characteristic of mobile phones have
yielded conflicting results. A few ani-
mal studies, however, have suggest-
ed that low levels of RF could accel-
erate the development of cancer in
laboratory animals. In one study,
mice genetically altered to be predis-
posed to developing one type of can-
cer developed more than twice as
many such cancers when they were
exposed to RF energy compared to
controls. There is much uncertainty
among scientists about whether re-
sults obtained from animal studies
apply to the use of mobile phones.
First, it is uncertain how to apply the
results obtained in rats and mice to
humans. Second, many of the stud-
ies showed increased tumor devel-
opment used animals that had al-
ready been treated with cancer-
causing chemicals, and other studies
exposed the animals to the RF virtu-
ally continuously – up to 22 hours
per day.
For the past five years in the United
States, the mobile phone industry
has supported research into the safe-
ty of mobile phones. This research
has resulted in two findings in partic-
ular that merit additional study:
1. In a hospital-based, case-control
study, researchers looked for an as-
sociation between mobile phone use
and either glioma (a type of brain
cancer) or acoustic neuroma
(a benign tumor of the nerve
sheath). No statistically significant
association was found between mo-
bile phone use and acoustic neuro-
ma. There was also no association
between mobile phone use and glio-
mas when all types of gliomas were
considered together. It should be
noted that the average length of mo-
bile phone exposure in this study
was less than three years.
When 20 types of glioma were con-
sidered separately, however, an as-
sociation was found between mobile
phone use and one rare type of glio-
ma, neuroepithelliomatous tumors.
It is possible with multiple compari-
sons of the same sample that this as-
sociation occurred by chance. More-
over, the risk did not increase with
how often the mobile phone was
used, or the length of the calls. In
fact, the risk actually decreased with
cumulative hours of mobile phone
use. Most cancer causing agents in-
crease risk with increased exposure.
An ongoing study of brain cancers by
the National Cancer Institute is ex-
pected to bear on the accuracy and
repeatability of these results.
1
