Scientists who tracked the health of 420,000
Danish cell phone users found no sign the devices cause cancer, the
biggest study yet to provide reassurance about the phones' safety--
but one that won't completely settle the controversy.
The study, published in Wednesday's Journal of the National
Cancer Institute, found no link between cell phones and brain and
nervous system cancers, leukemia or salivary gland tumors, the
cancer types that have worried critics.
"Every which way we looked at it, we could not find any
suggestive evidence for elevated risks," said John Boice of the
International Epidemiology Institute, who co-authored the study
with Christoffer Johansen of Copenhagen's Danish Cancer Society.
Taken together with two smaller U.S. studies that, in December,
found no cancer risk, the research should "minimize the concern
and fears that the public has with regard to the use of these
phones and cancer risk," he added.
But it won't end cancer questions, because while several
thousand Danes had used their phones for over 10 years _ the time
it can take a slow-growing brain tumor to appear _ the majority
used them for about three years.
Consequently, "this study ... should not be taken as the final
answer to the cell phone-cancer issue," said University of
Washington professor Henry Lai, whose laboratory research helped
spark concern when he linked cell phone signals with damage to rat
Cell phones work by beaming radiofrequency energy, a type of
low-powered radiation that many radiation specialists believe isn't
high enough to cause harm. But much of the RF waves are beamed from
the phones' antenna, right by the brain. Most studies haven't found
any cancer risk, but a few, like Lai's and a recent Swedish study
that found brain tumors more likely on the side of the head on
which cell phones were used, have raised concern.
Johansen gathered cell phone company records to compile a list
of Danes who began using the phones anytime since 1982. He matched
those names to the Danish Cancer Registry, a unique database that
tracks every Dane, from birth, who gets any type of cancer. By
using such precise statistics, Boice and Johansen could track
whether cell phone users suffer cancer at the same rate as other
Based on the national cancer rates, 161 cell phone users should
have suffered brain or nervous system cancer, but only 154 did.
Similarly, there were 84 leukemia cases instead of an expected 86,
and seven salivary gland tumors instead of the expected nine.