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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 world to ensure that high priority
animal studies are conducted to address important questions about the
effects of exposure to radio frequency energy (RF).
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