User's Manual
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 continuouslyup 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.(1)
2. 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 Telecommunication 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.