User's Manual

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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.
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.
6. 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. 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.
FDA and the Cellular Telecommunications & Internet Association (CTIA) have a formal Cooperative Research
and Development Agreement (CRADA) to do research on wireless phone safety. FDA provides the scientific
oversight, obtaining input from experts in government, industry, and academic organizations. CTIA-funded
research is conducted through contracts to independent investigators.
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