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Section 4A: Safety Guidelines 139
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 radiofrequency 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.
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 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
radiofrequency energy (RF).
FDA has been a leading participant in the World Health Organization
International Electromagnetic Fields (EMF) Project since its inception in 1996.