group activities, as well.
FDA shares regulatory responsibilities for wireless phones with the Federal
Communications Commission (FCC). All phones that are sold in the United
States must comply with FCC safety guidelines that limit RF exposure.
FCC relies on FDA and other health agencies for safety questions about
wireless phones.
FCC also regulates the base stations that the 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 primary subject
of the safety questions discussed in this document.
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 radio frequency 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 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 phones 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.
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 ten or more years' follow-up may be needed to
