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S AFETY
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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 Radio Frequency (RF) energy
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
Radio Frequency (RF) energy 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.