80
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. 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. The 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:
Two groups of 18 people were exposed to simulated mobile phone
signals under laboratory conditions while they performed cognitive
function tests. 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.
81
3. In a 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. The 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.
What is known about cases of human cancer that have been reported
in users of handheld mobile phones?
Some people who have used mobile phones have been diagnosed
with brain cancer. But it is important to understand that this type of
cancer also occurs among people who have not used mobile phones.
In fact, brain cancer occurs in the U.S. population at a rate of about 6
new cases per 100,000 people each year. At that rate, assuming 80
million users of mobile phones (a number increasing at a rate of about
1 million per month), about 4800 cases of brain cancer would be
expected each year among those 80 million people, whether or not
they used their phones. Thus it is not possible to tell whether any
individual’s cancer arose because of the phone, or whether it would
have happened anyway. A key question is whether the risk of getting a
particular form of cancer is greater among people who use mobile
phones than among the rest of the population. One way to answer that
question is to compare the usage of mobile phones among people
with brain cancer with the use of mobile phones among appropriately
matched people without brain cancer. This is called a case-control
study. The current case-control study of brain cancers by the National
Cancer Institute, as well as the follow-up research to be sponsored by
industry, will begin to generate this type of information.
What is the FDA’s role concerning the safety of mobile phones?
Under the law, the FDA does not review the safety of radiation-
emitting consumer products such as mobile phones before marketing,
as it does with new drugs or medical devices. However, the agency
has authority to take action if mobile phones are shown to emit
radiation at a level that is hazardous to the user. In such a case, the
FDA could require the manufacturers of mobile phones to notify users
of the health hazard and to repair, replace, or recall the phones so that
the hazard no longer exists.