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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:
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.
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Safety Guidelines
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 on-
going study of brain cancers by the National Cancer Institute is
expected to bear on the accuracy and repeatability of these results.
1. 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, 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.
2. 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.