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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
