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Consumer Update
Consumer Update
Consumer Update on Mobile Phones
(Published by U.S. Food and Drug Administration, Center for Devices
and Radiological Health, October 20, 1999.)
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 to questions.
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 does not demonstrate any
adverse health effects associated with the use of mobile phones.
What kind 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 primary source 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 handheld 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:
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 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