| Mobile
phones warm your ear
The temperature in and around
your ear rises when you use a mobile
phone – by at least 2 degrees.
 |
A
HOT EAR: Infrared imagery shows how the ear’s
temperature increases when a turned-off mobile phone is held
against it for 30 minutes.
Contact: Gunnhild Oftedal,
HiST/NTNU
Tel: +47 73 55 94 46
E mail: Gunnhild.Oftedal@aft.hist.no |
| Photo:Gunnhild Oftedal |
What is the connection between the use
of mobile telephones and physiological head problems? Is your mobile
to blame if your head feels hot or cold, if you experience headaches
or develop a brain tumour? A recent study shows that the use of mobile
phones does in fact increase the temperature in and around the ear
against which the mobile is held. The reason behind the increase may
surprise you, however.
A 1.6-DEGREE INCREASE – BUT
WHY?
Associate professor Gunnhild Oftedal at the Sør- Trøndelag
University College (HiST) had previously conducted a survey in Norway
and Sweden where she asked 12 000 individuals if they had ever experienced
discomfort from using their mobile phones.
Twenty-three per cent of Norwegians and 8.7
per cent of Swedes answered affirmatively. The sensation of heat
was the most common problem listed. Along with Professor Anders
Johnsson and Aksel Straume, a PhD student at NTNU, Oftedal has recently
completed a new lab study based on Straume’s doctoral research.
The researchers examined whether or not the
use of mobile phones leads to an increase in temperature, and if
yes,why?
They asked a young, healthy man to hold his
mobile against his ear for half an hour. The result was an increase
in temperature around the ear of 1.6 degrees Celsius. The conclusion
seems obvious: the radiation from the telephone must have caused
the warming. But not so. The phone was switched off and without
power.
The experiment was then repeated with a phone
that was switched on, but with an antenna that had been altered
so that it did not send or receive signals. The result was an additional
increase in temperature of 0.6 – 0.7 degrees. Finally, the
test subject was given a fully functional phone that had been switched
on and had an active antenna. This time there was no detectable
change in temperature.
“This suggests that the warming can
be explained by the insulation from a piece of plastic covering
the ear,” says Oftedal. In other words: any plastic object
of the same shape and size would have the same effect. The increase
in temperature when the phone was switched on was simply caused
by the battery heating up the plastic.
ARE WE COOKING OUR BRAINS?
When scientists talk of possible health hazards due to the use of
mobile phones, they explain it in terms of thermal and non-thermal
effects. Thermal effects refer to the biological changes caused
by increased temperatures in body tissue, where electromagnetic
fields cause the warming. Increases of more than 1 degree Celsius
may lead to health problems. It has been documented, for example,
that an increase of 1-2 degrees in the eye may damage it. Non-thermal
effects are when electromagnetic radiation affects us in ways other
than by heating us up.
One issue is whether the use of active mobile
phones may cause the head’s temperature increase. Another
matter is whether or not this warming is a health risk. Damage to
the eye has already been described as one effect. More diffuse problems
like headaches are also possible side effects of mobile phone use.
But are these problems caused by warming alone? The electromagnetic
radiation from mobile phones may well affect us in other ways, too.
Oftedal stresses that scientists are skating on thin ice when discussing
these issues. They know little about the cause-and-effect mechanisms
involved, and hence cannot eliminate the possibility that the effect
of electromagnetic fields, however weak in mobile phones,may cause
health problems.
MOBILE PHONES AND HEADACHES
Because of these many unknowns, a new survey is under way. The goal
is to determine if there is a connection between electromagnetic
radiation in mobile phones and headaches. The plan is to seek out
individuals who experience headaches they believe result from the
use of mobile phones. “The participants will be observed in
two different situations: one in which they are exposed to electromagnetic
fields similar to those in mobile phones, and one in which they
are not.
The study will be what we call a double blind
study – meaning that neither the subject nor the researcher
will know when they are being exposed. In this way we hope to get
scientifically sound evidence,” says Gunnhild Oftedal.
Tore Oksholen
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