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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 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).
Safety
Safety
3. What kinds of phones are the subject of this update?
The term “wireless phone” refers here to handheld wireless
phones with built-in antennas, often called “cell”, “mobile”, or
“PCS” phones. These types of wireless phones can expose the
user to measurable radiofrequency energy (RF) because of the
short distance between the phone and the user’s head.
These RF exposures are limited by FCC safety guidelines that
were developed with the advice of the FDA and other federal
health and safety agencies. When the phone is located at
greater distances from the user, the exposure to RF is drastically
lower because a person's RF exposure decreases rapidly with
increasing distance from the source. The so-called “cordless
phones,” which have a base unit connected to the telephone
wiring in a house, typically operate at far lower power levels,
and thus produce RF exposures far below the FCC safety limits.
4. 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
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