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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; how-
ever, 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 meth-
ods. Animal experiments investigating the effects of RF exposures char-
acteristic 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 ge-
netically altered to be predisposed to developing one type of cancer de-
veloped more than twice as many such cancers when they were exposed
to RF energy compared to controls. There is much uncertainty among sci-
entists about whether results obtained from animal studies apply to the
use of mobile phones. First, it is uncertain how to apply the results ob-
tained 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 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.
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 aber-
rations, 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.
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