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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.
1
2. Researchers conducted a large battery of laboratory tests to assess the effect 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 from 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.
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 test. 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 noted among more than 20 variables compared.
3
2. In study of 209 brain tumor cases and 425 matched controls, there was no increased risk of brain
tumors associated with mobile phone use. When tumors did exist in certain locations, however, they
were more likely to be on the side of the head where the mobile phone was used. Because this
occurred in only a small number of cases, the increased likelihood was too small to be statistically
significant.
4
In summary, we do not have enough information at this point to assure the
public that there are, or are not, any low incident health problems associated
with use of mobile phones. FDA continues to work with all parties, including
other federal agencies and industry, to assure that research is undertaken to
provide the necessary answers to the outstanding questions about the safety
of mobile phones.
