June 26, 2006
Cell phone signals excite brain: study
WASHINGTON (Reuters) - Cell phone emissions excite the part
of the brain cortex nearest to the phone, but it is not clear
if these effects are harmful, Italian researchers reported on
Their study, published in the Annals of Neurology, adds to
a growing body of research about mobile phones, their possible
effects on the brain, and whether there is any link to cancer.
About 730 million cell phones are expected to be sold this
year, according to industry estimates, and nearly 2 billion
people around the world already use them.
Of these, more than 500 million use a type that emits
electromagnetic fields known as Global System for Mobile
communications or GSM radio phones. Their possible effects on
the brain are controversial and not well understood.
Dr. Paolo Rossini of Fatebenefratelli hospital in Milan and
colleagues used Transcranial Magnetic Stimulation or TMS to
check brain function while people used these phones.
They had 15 young male volunteers use a GSM 900 cell phone
for 45 minutes. In 12 of the 15, the cells in the motor cortex
adjacent to the cell phone showed excitability during phone use
but returned to normal within an hour.
The cortex is the outside layer of the brain and the motor
cortex is known as the "excitable area" because magnetic
stimulation has been shown to cause a muscle twitch.
The researchers stressed that they had not shown that using
a cell phone is bad for the brain in any way, but people with
conditions such as epilepsy, linked with brain cell
excitability, could potentially be affected.
"It should be argued that long-lasting and repeated
exposure to EMFs (electromagnetic frequencies) linked with
intense use of cellular phones in daily life might be harmful
or beneficial in brain-diseased subjects," they wrote.
"Further studies are needed to better circumstantiate these
conditions and to provide safe rules for the use of this
increasingly more widespread device."
Medical studies on cell phone use have provided mixed
results. Swedish researchers found last year that using cell
phones over time can raise the risk of brain tumors. But a
study by Japan's four mobile telephone operators found no
evidence that radio waves from the phones harmed cells or DNA.
The Dutch Health Council analyzed several studies and found
no evidence that radiation from mobile phones was harmful.