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Safety Guidelines
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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 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.
FDA belongs to an interagency working group of the federal
agencies that have responsibility for different aspects of RF safety
to ensure coordinated efforts at the federal level. The following
agencies belong to this working group:
• National Institute for Occupational Safety and Health
• Environmental Protection Agency
• Federal Communications Commission
• Occupational Safety and Health Administration
• National Telecommunications and Information Administration
The National Institutes of Health participates in some interagency
working group activities, as well.
FDA shares regulatory responsibilities for wireless phones with the
Federal Communications Commission (FCC). All phones that are
sold in the United States must comply with FCC safety guidelines
that limit RF exposure. FCC relies on FDA and other health
agencies for safety questions about wireless phones.
FCC also regulates the base stations that the wireless phone
networks rely upon. While these base stations operate at higher
power than do the wireless phones themselves, the RF exposures
that people get from these base stations are typically thousands of
times lower than those they can get from wireless phones. Base
stations are thus not the subject of the safety questions discussed
in this document.
3. What kinds of phones are the subject of this update?
The term “wireless phone” refers here to hand-held 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 Federal Communications
Commission safety guidelines that were developed with the advice of
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.