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questions about wireless phones.
FCC also regulates the base stations that the wireless phone networks rely upon. While these base
stations operate at higher power than do the wireless phones 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 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 radio frequency 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.
