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 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 longterm 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 the FDA doing to find out more
about the possible health effects of
wireless phone 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 radiofrequency energy
(RF). The FDA has been a leading participant
in the World Health Organization International
Electromagnetic Fields (EMF) Project since
its inception in 1996. An influential result
Safety Guidelines