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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 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.