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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.
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 tests. There were no changes in the
subject's 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 changes noted among more than 20
variables compared.
2. 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 on only a small number of cases, the increased
likelihood was too small to be statistically significant.
1. Muscat et al. Epidemiological Study of Cellular Telephone Use and Malignant Brain Tumors. In: State
of the Science Symposium; 1999 June 20; Long Beach, California.
2. Tice et al. Tests of mobile phone signals for activity in genotoxicity and other laboratory assays. In:
Annual Meeting of the Environment Mutagen Society; March 29, 1999, Washington, D.C.; and personal
communication, unpublished results.
3. Preece, AW, Iwi, G, Davies-Smith, A, Wesnes, K, Butler, S, Lim, E, and Varey, A. Effect of a 915-MHz
simulated mobile phone signal on cognitive function in man. Int.. J. Radiat. Biot., April 8, 1999.
4. Hardell, L, Nasman, A, Pahlson, A, Hallquist, A and Mild, KH. Use of cellular telephones and the risk
for brain tumors: a case-control study. Int. J. Oncol., 15: 113-116, 1999
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.
What is known about cases of human cancer that have been reported in users
of hand-held 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 uses 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
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.
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