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networks rely upon. While these base stations operate at higher power than do the wireless
devices themselves, the RF exposures that people get from these base stations are typically
thousands of times lower than those they can get from wireless devices. Base stations are thus
not the primary subject of the safety questions discussed in this document.
3. What kinds of devices are the subject of this update?
The term “wireless device” refers here to hand-held wireless devices with built-in antennas,
often called “cell,” “mobile,” or “PCS” devices. These types of wireless devices can expose the
user to measurable radiofrequency energy (RF) because of the short distance between the
device 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 device 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 devices," 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.
4. What are the results of the research done already?
The research done thus far has produced conicting results, and many studies have
suered from aws in their research methods. Animal experiments investigating the eects
of radiofrequency energy (RF) exposures characteristic of wireless devices have yielded
conicting 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 devices, 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 devices
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 eects from wireless device RF exposures. However, none of the studies
can answer questions about long-term exposures, since the average period of device use in
these studies was around three years.