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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 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 phones 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.
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 ten 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.
