Nokia 1100 Manual Del Usuario página 50

wireless phone networks rely upon. While these base stations operate at higher power than
do the wireless phones themselves, the RF exposures that people get from these base stations
are typically thousands of times lower 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 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.
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