![background image](http://html.mh-extra.com/html/samsung/tracfone/tracfone_user-manual_1189585071.webp)
Health and Safety Information 67
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 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.