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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
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
X70_US_Text.fm Page 140 Tuesday, March 9, 2004 1:21 PM