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methods. Animal experiments investigating the effects of radio
frequency 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.
20. 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
Section 4: Safety Guidelines and Warranty Information
4A: Safety 206
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