Consumer Update on Mobile Phones
FDA has been receiving inquiries about
the safety of mobile phones, including cellular phones and PCS phones.
The following summarizes what is known--and what remains unknown--about
whether these products can pose a hazard to health, and what can be done
to minimize any potential risk. This information may be used to respond
Why the concern?
Mobile phones emit low levels of radiofrequency
energy (i.e., radiofrequency radiation) in the microwave range while being
used. They also emit very low levels of radiofrequency energy (RF), considered
non-significant, when in the stand-by mode. It is well known that high
levels of RF can produce biological damage through heating effects (this
is how your microwave oven is able to cook food). However, it is not known
whether, to what extent, or through what mechanism, lower levels of RF
might cause adverse health effects as well. Although some research has
been done to address these questions, no clear picture of the biological
effects of this type of radiation has emerged to date. Thus, the available
science does not allow us to conclude that mobile phones are absolutely
safe, or that they are unsafe. However, the available scientific evidence
not demonstrate any adverse health effects associated with the use
of mobile phones.
What kinds of phones are in question?
Questions have been raised about hand-held
mobile phones, the kind that have a built-in antenna that is positioned
close to the user's head during normal telephone conversation. These types
of mobile phones are of concern because of the short distance between the
phone's antenna--the primarysource of the RF--and the person's head. The
exposure to RF from mobile phones in which the antenna is located at greater
distances from the user (on the outside of a car, for example) is drastically
lower than that from hand-held phones, because a person's RF exposure decreases
rapidly with distance from the source. The safety of so-called "cordless
phones," which have a base unit connected to the telephone wiring in a
house and which operate at far lower power levels and frequencies, has
not been questioned.
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; however, 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 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:
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.
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
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.
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.
Two other studies of interest have
been reported recently in the literature:
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.
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.
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.
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 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 FDA's role concerning the
safety of mobile phones?
Under the law, 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, 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.
Although the existing scientific data
do not justify FDA regulatory actions at this time, FDA has urged the mobile
phone industry to take a number of steps to assure public safety. The agency
has recommended that the industry:
support needed research into possible
biological effects of RF of the type emitted by mobile phones;
design mobile phones in a way that minimizes
any RF exposure to the user that is not necessary for device function ;
At the same time, FDA belongs to an interagency
working group of the federal agencies that have responsibility for different
aspects of mobile phone safety to ensure a coordinated effort at the federal
level. These agencies are:
cooperate in providing mobile phone users
with the best possible information on what is known about possible effects
of mobile phone use on human health.
The National Institutes of Health also
participates in this group.
National Institute for Occupational Safety
Environmental Protection Agency
Federal Communications Commission
Occupational Health and Safety Administration
National Telecommunications and Information
In the absence of conclusive information
about any possible risk, what can concerned individuals do?
If there is a risk from these products--and
at this point we do not know that there is--it is probably very small.
But if people are concerned about avoiding even potential risks, there
are simple steps they can take to do so. For example, time is a key factor
in how much exposure a person receives. Those persons who spend long periods
of time on their hand-held mobile phones could consider holding lengthy
conversations on conventional phones and reserving the hand-held models
for shorter conversations or for situations when other types of phones
are not available.
People who must conduct extended conversations
in their cars every day could switch to a type of mobile phone that places
more distance between their bodies and the source of the RF, since the
exposure level drops off dramatically with distance. For example, they
could switch to
a mobile phone in which the antenna is
located outside the vehicle,
a hand-held phone with a built-in antenna
connected to a different antenna mounted on the outside of the car or built
into a separate package, or
Again, the scientific data do not demonstrate
that mobile phones are harmful. But if people are concerned about the radiofrequency
energy from these products, taking the simple precautions outlined above
can reduce any possible risk.
a headset with a remote antenna to a mobile
phone carried at the waist.
Where can I find additional information?
For additional information, see the
Federal Communications Commission (FCC)
RF Safety Program (select "Information on Human Exposure to RF Fields from
Cellular and PCS Radio Transmitters"): http://www.fcc.gov/oet/rfsafety
World Health Organization (WHO) International
Commission on Non-Ionizing Radiation Protection (select Qs & As): http://www.who.int/emf
Muscat et al. Epidemiological Study of Cellular Telephone Use and Malignant
Brain Tumors. In: State of the Science Symposium;1999 June 20; Long Beach,
2. Tice et
al. Tests of mobile phone signals for activity in genotoxicity and other
laboratory assays. In: Annual Meeting of the Environmental Mutagen Society;
March 29, 1999, Washington, D.C.; and personal communication, unpublished
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. Biol., April 8, 1999.
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:
Updated October 20, 1999