2.10.02
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i 37 Am Engl, A31008-H5450-A5-2-4A19
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U.S. FDA
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 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 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.
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