Answers
02/04/1993
UPDATE ON CELLULAR PHONES
T93-7 Sharon Snider
Feb. 4, 1993 (301) 443-3285
UPDATE ON CELLULAR PHONES
FDA has been receiving inquiries about the safety of cellular 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 to
questions.
Why the concern?
Cellular phones emit low levels of radiofrequency energy (specifically,
microwave energy) while being used. (No significant amounts of radiofrequency
energy are emitted when the phones are not in use.) It is known that high
levels of radiofrequency energy can produce biological damage, and there is
limited evidence that suggests that lower levels might cause adverse health
effects as well. However, there is no proof at this point that cellular
phones are harmful.
What kind of phones are in question?
Questions have been raised about hand-held cellular phones, the kind that
have a built-in antenna that is positioned close to the user's head during
normal telephone conversations. These types of cellular phones are of
particular concern because of the short distance between the phone's antenna
-- the source of the radiofrequency energy -- and the person's body. Cellular
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phones in which the antenna is located at greater distances from the user or
other people (on the outside of a car, for example) are generally of little
concern, because a person's exposure to a radiofrequency source decreases
rapidly with distance. 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 cellular phones might be harmful?
Briefly, there is not enough evidence to know for sure, either way.
Although it is known that high levels of radiofrequency energy that are
absorbed by the body can be harmful, the effect of lower levels, such as those
emitted by hand-held cellular phones, is far less clear. A few studies
suggest that these levels can accelerate the development of cancer in
laboratory animals, but there is much uncertainty among scientists about
whether these results apply to the use of cellular phones. For example, it is
uncertain whether the results obtained in rats and mice are applicable to
humans. Further, most 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 radiofrequency energy virtually
continuously -- up to 22 hours a day.
Nonetheless, we cannot dismiss these studies as irrelevant to cellular
phone users. We simply don't have enough information at this point to rule
out the possibility of a risk. FDA is actively working with all parties,
including other federal agencies and industry, to assure that research is
undertaken to provide the necessary answers to outstanding public health
questions.
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What about cases of human cancer that have been reported in users of hand-held
cellular phones?
It is true that some people who have used these phones have experienced
brain cancer. But it is important to understand that this type of cancer also
occurs among people who have not used cellular 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 3 million users of hand-held
cellular phones, about 180 cases of brain cancer would be expected each year
among those 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 these
phones than among the rest of the population. One way to answer that question
is to compare the cancer rates among people using hand-held cellular phones
with people who do not use them. These kinds of human studies do not exist at
this time.
What is FDA's role concerning the safety of cellular phones?
Under the law, FDA does not review the safety of cellular phones prior to
marketing, as it does with new drugs or medical devices. However, because the
phones emit radiofrequency energy, the agency could impose certain
restrictions if health problems were to arise after marketing. For example,
FDA could impose a performance standard on the manufacturers of these products
if the scientific evidence showed a public health need. Such a standard might
require that the phones emit radiofrequency energy below a certain level.
Existing scientific data do not justify FDA's taking this action. However,
the agency is exploring with the manufacturers of hand-held cellular phones
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ways to minimize exposure of users to radiofrequency energy, such as changes
in antenna design and better instructions for use, as well as areas for needed
research.
In the absence of conclusive information about any possible risk, what should
people do?
It is not necessary that people stop using their hand-held cellular
phones. If there is a risk from these devices -- and at this point we don't
know if there is -- it is probably small. But if people are concerned about
avoiding even potential risks, there are simple steps they can take to do so.
For example, since time is a key factor in how much exposure a person
receives, those who spend long periods of time on their hand-held cellular
phones could consider holding lengthy conversations on conventional phones and
reserving the hand-held cellular models for shorter conversations or for
situations when conventional phones are not available.
People who must conduct extended conversations in their cars every day
could switch to a type of cellular phone that places more distance between
their bodies and the source of the radiofrequency energy, since the exposure
level drops off dramatically with distance. For example, they could switch to
a cellular phone in which the antenna is located outside the vehicle; in some
cases, a hand-held phone with a built-in antenna can be connected to a
different antenna mounted on the outside of the car or built into a separate
package. Note that outside antennas should be mounted as far as possible from
passengers.
Again, there is no proof at this point that cellular phones can be
harmful. But if people are concerned about the radiofrequency energy from
these products, taking the simple precautions outlined above can reduce any
possible risk.