Today, mobile telephony is now commonplace around the world.
This wireless technology relies upon an extensive network of fixed antennas, or
base stations, relaying information with radiofrequency (RF). Over 1.4 million
base stations worldwide, and the number is increasing dramatically with the
advent of third generation technologies.
Other wireless networks that allow access and services to
high-speed Internet, such as local area networks (WLANs), are also increasingly
common in homes, offices and many public places (airports, schools and residential
and urban areas). As an increasing number of base stations and local wireless
networks increases, so does the population exposure to radio frequencies.
Recent studies show that RF exposure from base stations range from 0.002% to 2%
of the levels specified in international guidelines on exposure limits, based
on a number of factors including the proximity of the antennas and their
environment. This is lower or comparable to RF exposures from radio
transmitters or TV.
Possible health consequences from exposure to RF fields
produced by wireless technologies have caused concern. In this fact sheet
reviews the scientific evidence on the effects on human health of exposure to
continuous low-level base stations and other local wireless networks. For detailed
information on a WHO workshop on this theme.
Health concerns
A common concern about in relation to the antennas of base
stations and wireless local networks is related to long-term effects it could
have on the health of the whole body exposure to RF energy. To date, the only
effect of RF fields on health has been noted in scientific studies related to
an increase in body temperature (> 1 ° C) by exposure to a field strength
very high that only occurs in certain industrial facilities, such as RF heaters.
The levels of RF exposure from base stations and wireless networks are so low
that the temperature increases are insignificant and do not affect the health
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The strength of RF fields reaches its maximum at the origin
and decreases rapidly with distance. Access to places close to the antennas of
base stations is restricted where RF signals may exceed international exposure
limits. A number of recent studies have shown that RF exposure from base
stations and wireless technologies in publicly accessible areas (including
schools and hospitals) are normally thousands of times below the limits set by
international standards.
In fact, due to their lower frequency, to similar levels of
RF exposure, the body absorbs up to five times the signal from the FM radio and
television stations base. This is because the frequencies used in FM radio
(around 100 MHz) and television (between 300 and 400 MHz) are lower than those
employed in mobile telephony (900 and 1800 MHz), since the height people makes
the body an efficient receiving antenna. In addition, stations broadcast radio
and television work for at least 50 years without experiencing any adverse
health effect.
While most radio technologies have used analog signals,
modern wireless telecommunications are using digital signals. Detailed reviews
conducted so far have not revealed any hazard specific to different RF
modulations.
Cancer: the news published by the media on clusters of cases
of cancer around base stations mobile phones have alerted the public. It should
be noted that from the geographical point of view, cancer is unevenly
distributed among any population. Given the widespread presence of base
stations in the environment can result in clusters of cancer cases near base
stations merely by chance. In addition, cases of cancer reported in these
clusters are often of different types with no common characteristics, so it is
not likely to have a common cause.
You can obtain evidence on the distribution of cancer cases
among the population through epidemiological studies carefully planned and
executed. In the past 15 years, have published studies that examined the
potential relationship between RF transmitters and cancer. These studies have
found no evidence that RF exposure from the transmitters increases the risk of
cancer. Similarly, the long-term studies in animals have not established an
increased risk of cancer from exposure to RF fields, even at levels much higher
than produced by base stations and wireless networks.
Other effects: Few studies on the overall impact on human
health from exposure to RF fields from base stations. This is due to the
difficulty in distinguishing possible health effects of very low signals
emitted by base stations of other RF signals higher strength in the environment.
Most studies have focused on the RF exposure from mobile phone users. Studies
with humans and animals in which we have examined the brain waves, cognition
and behavior after exposure to RF fields, such as those generated by mobile
phones, have not identified adverse effects. The RF exposure level used in
these studies were about 1000 times higher than the general public exposure to
RF from base stations or wireless networks. No evidence of altered sleep or
cardiovascular function.
Some individuals have reported nonspecific symptoms
following exposure to RF fields from base stations and other EMF devices. As
indicated in a recent fact sheet published by the WHO fact sheet
"Electromagnetic Hypersensitivity", there is no evidence that
electromagnetic fields cause such symptoms. However, it is important to
consider the plight of people suffering from these symptoms.
From all evidence accumulated so far, none has shown that
the RF signals produced by base stations have adverse short or long term
health. Since wireless networks produce generally lower RF signals than base
stations, there are expected from exposure to them is injurious to amerihealth mercy insurance.
Protection rules
The International Commission on Non-Ionizing Radiation
Protection (ICNIRP, 1998) and the Institute of Electrical and Electronics
Engineers (IEEE, 2005) have developed international guidelines on exposure
limits to protect against known effects of RF fields.
National authorities should adopt international standards to
protect citizens against adverse levels of RF. They should restrict access to
areas that may be exceeded exposure limits.
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