109
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 do not 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 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.