User's Manual

IMPORTANT SAFETY INFORMATION
101
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.