User Manual

For Your Safety 154
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 devices, so we do not
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
devices 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 device RF
exposures. However, none of the studies can answer questions about long-term
exposures, since the average period of device use in these studies was around three
years.
5. What research is needed to decide whether RF exposure
from wireless devices poses a health risk?
A combination of laboratory studies and epidemiological studies of people
actually using wireless devices 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 ten 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 devices. Many factors affect
this measurement, such as the angle at which the device is held, or which model of
device is used.
6. What is the FDA doing to find out more about the possible
health effects of wireless device RF?
The 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 Radio
Frequency (RF) energy.