3. What kinds of phones are the subject of this update?
The term 'wireless phone' refers here to handheld wireless phones with builtin 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 predisposed 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 longterm 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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