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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
angle at which the phone is held, or which model of
phone is used.
6. What is the FDA doing to find out more about the
possible health effects of wireless phone RF?
The FDA is working with the U.S. National Toxicology
Program and with groups of investigators around the
world to ensure that high priority animal studies are
conducted to address important questions about the
effects of exposure to radio frequency energy (RF).
The FDA has been a leading participant in the World
Health Organization International Electromagnetic Fields
(EMF) Project since its inception in 1996. An influential
result of this work has been the development of a
detailed agenda of research needs that has driven the
establishment of new research programs around the
world. The project has also helped develop a series of
public information documents on EMF issues.
The FDA and the Cellular Telecommunications &
Internet Association (CTIA) have a formal Cooperative
Research and Development Agreement (CRADA) to do
research on wireless phone safety. The FDA provides
the scientific oversight, obtaining input from experts in
government, industry, and academic organizations.
CTIA-funded research is conducted through contracts
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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
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.
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
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