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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.
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.
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