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Section 4A: Safety Guidelines 170
phones. Base stations are thus not the primary subject of the safety questions
discussed in this document.
What kinds of phones are the subject of this update?
The term "wireless phone" refers here to hand-held wireless phones with built-
in antennas, often called "cell," "mobile," or "PCS" phones. These types of
wireless phones can expose the user to measurable radiofrequency energy (RF)
because of the short distance between the phone and the user's head. These RF
exposures are limited by Federal Communications Commission safety
guidelines that were developed with the advice of FDA and other federal health
and safety agencies. When the phone is located at greater distances from the
user, the exposure to RF is drastically lower because a person's RF exposure
decreases rapidly with increasing distance from the source. The so-called
"cordless phones," which have a base unit connected to the telephone wiring in
a house, typically operate at far lower power levels, and thus produce RF
exposures well within the FCC's compliance limits.
What are the results of the research done already?
The research done thus far has produced conflicting results, and many studies
have suffered from flaws in their research methods. Animal experiments
investigating the effects of radiofrequency energy (RF) exposures characteristic
of wireless phones have yielded conflicting results that often cannot be
repeated in other laboratories. A few animal studies, however, have suggested
that low levels of RF could accelerate the development of cancer in laboratory
animals. However, many of the studies that showed increased tumor
development used animals that had been genetically engineered or treated with
cancer-causing chemicals so as to be pre-disposed to develop cancer in the
absence of RF exposure. Other studies exposed the animals to RF for up to 22
hours per day. These conditions are not similar to the conditions under which
people use wireless phones, so we don't know with certainty what the results of
such studies mean for human health.
Three large epidemiology studies have been published since December 2000.
Between them, the studies investigated any possible association between the
use of wireless phones and primary brain cancer, glioma, meningioma, or
acoustic neuroma, tumors of the brain or salivary gland, leukemia, or other
cancers. None of the studies demonstrated the existence of any harmful health
effects from wireless phone RF exposures. However, none of the studies can
answer questions about long-term exposures, since the average period of phone
use in these studies was around three years.
What research is needed to decide whether RF exposure from wireless
phones poses a health risk?
A combination of laboratory studies and epidemiological studies of people
actually using wireless phones would provide some of the data that are needed.
Lifetime animal exposure studies could be completed in a few years. However,
very large numbers of animals would be needed to provide reliable proof of a
cancer promoting effect if one exists. Epidemiological studies can provide data