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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; however, 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 investigating the effects of RF
exposures characteristic of mobile phones have
yielded conflicting results. A few animal studies,
however, have suggested that low levels of RF could
accelerate the development of cancer in laboratory
animals. In one study, mice genetically altered to be
predisposed to developing one type of cancer
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 results 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 studies
that showed increased tumor development used
animals that had already been treated with cancer-
causing chemicals, and other studies exposed the
animals to the RF virtually 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 safety of mobile phones. This research has
resulted in two findings in particular that merit
additional study:
1. In a hospital-based, case-control study,
researchers looked for an association 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 mobile
phone use and acoustic neuroma. There was
also no association between mobile phone use
and gliomas when all types of types of gliomas
were considered together. It should be noted that
the average length of mobile phone exposure in
this study was less than three years.
When 20 types of glioma were considered
separately, however, an association was found
between mobile phone use and one rare type of
glioma, neuroepithelliomatous tumors. It is possible
with multiple comparisons of the same sample that
this association occurred by chance. Moreover, 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
increase risk with increased exposure. An ongoing
study of brain cancers by the National Cancer
Institute is expected to bear on the accuracy and
repeatability of these results
2. Researchers conducted a large battery of
laboratory tests to assess the effects of exposure
to mobile phone RF on genetic material. These
included tests for several kinds of abnormalities,
including mutations, chromosomal aberrations,
DNA strand breaks, and structural changes in the
genetic material of blood cells called
lymphocytes. None of the tests showed any effect
of the RF except for the micronucleus assay,
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