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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.
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 predisposed 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 neu-roma, 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. The initial research will include both laboratory studies and studies of
wireless phone users. The CRADA will also include a broad assessment of additional research needs in the context
of the latest research developments around the world.
7. How can I find out how much radiofrequency energy exposure I can get by using my wireless phone?
All phones sold in the United States must comply with Federal Communications Commission (FCC) guidelines that
limit radiofrequency energy (RF) exposures. FCC established these guidelines in consultation with FDA and the
other federal health and safety agencies. The FCC limit for RF exposure from wireless telephones is set at a Specific
Absorption Rate (SAR) of 1.6 watts per kilogram (1.6 W/kg). The FCC limit is consistent with the safety standards
developed by the Institute of Electrical and Electronic Engineering (IEEE) and the National Council on Radiation
Protection and Measurement. The exposure limit takes into consideration the body’s ability to remove heat from the
tissues that absorb energy from the wireless phone and is set well below levels known to have effects. Manufacturers
of wireless phones must report the RF exposure level for each model of phone to the FCC. The FCC website (http://
www.fda.gov (under “c” in the subject index, select Cell Phones > Research)) gives directions for locating the FCC
identification number on your phone so you can find your phone’s RF exposure level in the online listing.
8. What has FDA done to measure the radiofrequency energy coming from wireless phones?
The Institute of Electrical and Electronic Engineers (IEEE) is developing a technical standard for measuring the
radiofrequency energy (RF) exposure from wireless phones and other wireless handsets with the participation
and leadership of FDA scientists and engineers. The standard, “Recommended Practice for Determining the Spatial-
Peak Specific Absorption Rate (SAR) in the Human Body Due to Wireless Communications Devices: Experimental
Techniques,” sets forth the first consistent test methodology for measuring the rate at which RF is deposited in the
heads of wireless phone users. The test method uses a tissue-simulating model of the human head. Standardized SAR
test methodology is expected to greatly improve the consistency of measurements made at different laboratories on
the same phone. SAR is the measurement of the amount of energy absorbed in tissue, either by the whole body or a
small part of the body. It is measured in watts/kg (or milliwatts/g) of matter. This measurement is used to determine
whether a wireless phone complies with safety guidelines.
9. What steps can I take to reduce my exposure to radiofrequency energy from my wireless phone?
If there is a risk from these products—and at this point we do not know that there is—it is probably very small. But if
you are concerned about avoiding even potential risks, you can take a few simple steps to minimize your exposure to
radiofrequency energy (RF). Since time is a key factor in how much exposure a person receives, reducing the amount
of time spent using a wireless phone will reduce RF exposure.
• If you must conduct extended conversations by wireless phone every day, you could place more distance between
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