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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
1
.
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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, which detects structural
effects on the genetic material. The cells in this
assay showed changes after exposure to
simulated cell phone radiation, but only after 24
hours of exposure. It is possible that exposing
the test cells to radiation for this long resulted in
heating. Since this assay is known to be
sensitive to heating, heat alone could have
caused the abnormalities to occur. The data
already in the literature on the response of the
micronucleus assay to RF are conflicting. Thus,
follow-up research is necessary
FDA is currently working with government, industry,
and academic groups to ensure the proper follow-
up to these industry-funded research findings.
Collaboration with the Cellular Telecommunications
Industry Association (CTIA) in particular is
expected to lead to FDA providing research
recommendations and scientific oversight of new
CTIA-funded research based on such
recommendations.
Two other studies of interest have been reported
recently in the literature:
1
Two groups of 18 people were exposed to
simulated mobile phone signals under
laboratory conditions while they performed
cognitive function tests. There were no changes
in the subjects' ability to recall words, numbers,
or pictures, or in their spatial memory, but they
were able to make choices more quickly in one
visual test when they were exposed to simulated
mobile phone signals. This was the only change
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2
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