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Appendix C: Consumer Update 97
APPENDIX C: 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 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:
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 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.
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