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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 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 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.
What is FDA doing to find out more about the
possible health effects of wireless phone RF?
FDA is working with the U.S. National Toxicology
Program and with groups of investigators around the
