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Appendix B Message from the FDA
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 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 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 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.