Motorola 2001 Portable Cell Phone Owner's Manual page 53

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:
a 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
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