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.
5. 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 that is directly applicable to human populations, but
10 or more years follow-up may be needed to provide
answers about some health effects, such as cancer. This is
because the interval between the time of exposure to a
cancer-causing agent and the time tumors develop — if
they do — may be many, many years. The interpretation
of epidemiological studies is hampered by difficulties in
measuring actual RF exposure during day-to-day use of
wireless phones. Many factors affect this measurement,
such as the angle at which the phone is held, or which
model of phone is used.
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themselves, the RF exposures that people get from these
base stations are typically thousands of times lower than
those they can get from wireless phones. Base stations
are thus not the subject of the safety questions discussed
in this document.
3. What kinds of phones are the subject of this update?
The term “wireless phone” refers here to handheld
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 FCC safety guidelines
that were developed with the advice of the 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 far below the FCC safety limits.
4. 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
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