Researchers at the National Cancer Institute (NCI) found that people
who used cellular phones did not have an increased risk of brain tumors
compared to non-users. The study, due to be published in the Jan.
11, 2001, issue of the New England Journal of Medicine (NEJM), was released
on Dec. 19.
The use of hand-held cellular phones involves placing a small
transmitter that emits radio frequency radiation next to the head.
There has been widespread public concern that this radiation might cause
tumors of the brain and nervous system. Because it is not known whether
the radiation from cell phones poses a cancer risk, NCI scientists included
cell phone use as part of a comprehensive study on the causes of brain
tumors that began in 1994.
The NCI adult brain tumor study involves about 800 adult brain
tumor cases and 800 controls (people without brain tumors) from three medical
institutions in Phoenix, Boston, and Pittsburgh. Data collection
was done by a structured personal interview in which participants were
asked specific questions about when they first began using a hand-held
cellular phone, date of last use, and the usual level of use. Information
about the specific make or model of the phone was not collected.
Data collection was completed in 1998.
The researchers found no evidence that a person’s risk of developing
a brain tumor increased with increasing years of use or average minutes
of use per day, nor did brain tumors among cellular phone users tend to
occur more often than expected on the side of the head on which the person
reported using their phone. Among high-level users were participants
who used the phones for an average of 15 or more minutes per day for at
least three years. Very few people used their phone frequently for
more than five years.
“We don’t see any evidence that cell phones cause brain tumors,”
said Peter D. Inskip, Sc.D., principal investigator for the study from
NCI’s Division of Cancer Epidemiology and Genetics in Bethesda, Md.
“But if an increased risk of brain tumors occurs only after five or more
years, or only among very heavy users, this study probably would not detect
The NCI study began in 1994 and was completed in 1998, during
a time when analogue phones were primarily used. Digital phones,
which operate at a higher frequency, are more commonly used today.
However, there is no evidence at this time that cancer risk would differ
for the two types of phones.
Similar results were seen in two other studies. One published
this month in the Journal of the American Medical Association by Muscat
et al, involved 469 brain tumor cases and 422 controls. The researchers
did not find an association between use of hand-held cellular telephones
and the risk of glioma, the most common form of brain cancer in adults.
A 1999 Swedish study by Hardell et al, involving 233 brain tumor cases
and 466 controls, also did not find an association between the amount of
cell phone use and the risk of brain tumors. The investigators reported
an association between side of the head on which the tumor occurred and
side of phone use, but this was based on a small number of brain tumor
There are three other types of wireless or mobile phones currently
on the market– car cellular phones, transportable cellular phones, and
cordless phones. All of these involve much lower radiation exposure
to the brain. With car cellular phones, the antenna is mounted on
the outside of the car some distance from the user. Transportable
cellular phones, or “bag phones,” have a transmitter with the battery pack
in a portable unit separate from the handset. Cordless phones have
a base unit wired to the land-line telephone service and typically operate
at a lower frequency and much lower power than cellular phones. If
hand-held cellular phones do not cause brain tumors, it would be surprising
if these other types of wireless phones do, because of the lower level
of radiation exposures.
The number of people using cell phones has increased dramatically
during the past 10 years, and this trend appears likely to continue.
According to the Cellular Telecommunications Industry Association, there
are currently about 107 million cellular phone subscribers in the United
States, increasing at a rate of about 2 million per month.
Because of the large number of users worldwide, there are several
other studies in progress involving cell phones and brain tumors.
The largest of these is a multicenter, international case-control study
involving about 3,000 cases and 3,000 controls, coordinated by the International
Agency for Research on Cancer (IARC), based in Lyon, France. Results
are expected in several years. A Danish study, which includes a cohort
of 550,000 cellular phone subscribers from 1982 to 1995, is expected to
be published soon.
In addition, a $10 million program on cell phone research was
recently announced in the United Kingdom. In the United States, the
Food and Drug Administration (FDA) and the Cellular Telecommunications
Industry Association (CTIA) have recently signed a Cooperative Research
and Development Agreement (CRADA), which stipulates that FDA will provide
scientific and technical guidance for studies which evaluate the health
effects of cellular phone use.
Because the causes of brain tumors are largely unknown, NCI scientists
conducting the adult brain tumor study are evaluating a wide range of environmental,
lifestyle, and genetic factors as possible risk factors. These include
workplace exposures to chemical agents and electromagnetic fields, dietary
factors, family history of tumors, genetic factors, home use of selected
appliances, reproductive history and hormonal exposures, viruses, and medical
and dental exposure to ionizing radiation. Results from these studies
will be reported in future publications. Because of intense public
interest, cellular phone use is the first report.