FEARS that mobile phones could cause brain tumours have resurfaced on the
back of two new epidemiological studies from Sweden and the US. However, the
findings are not clear-cut, leaving the field of cellphone safety just about as
confused as when 快猫短视频 investigated it last month (鈥淕et your
head round this鈥︹��, 10 April, p 20).
The Swedish study of 209 people with brain tumours and 425 matched controls
was led by Lennart Hardell at the 脰rebro Medical Centre. He found no overall
increased risk of brain tumours among people who used mobiles. But cellphone
users were about 2.5 times as likely as non-users to suffer tumours in the lobes
of the brain adjacent to their 鈥減hone ears鈥�. The problem is that there were so
few of these people鈥攋ust 13鈥攖hat Hardell and his colleagues can鈥檛
say for sure whether this was really linked to the patients鈥� phone use, or was
just a statistical artefact.
The Swedish research was featured in a Panorama television documentary
broadcast by the BBC on Monday this week, and will appear in a future issue of
the International Journal of Oncology. It has already been reviewed by
the National Radiological Protection Board in Didcot, Oxfordshire, which
monitors mobile phone safety for the British government. 鈥淭his study doesn鈥檛
tell us much that we didn鈥檛 already know, other than that we need larger, more
extensive studies,鈥� concludes John Stather, the board鈥檚 deputy director.
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The second study comes from Wireless Technology Research (WTR) in Washington
DC, the organisation set up by the mobile phone industry in the US to
investigate the health effects of its products. It has not yet been accepted for
publication, but reports a link between phone use and a type of brain tumour
called a neurocytoma.
George Carlo, WTR鈥檚 director, says the study focused on 450 people with brain
cancer, comparing them with 425 controls. Again, there was no overall link
between brain cancer and cellphone use. But of 30 people who had neurocytomas,
40 per cent had used mobiles鈥攃ompared with just 18 per cent of the
controls. Carlo says this result is statistically significant, and should be
followed up. 鈥淚 want to make sure people know what鈥檚 being found,鈥� he says.
Carlo describes WTR鈥檚 findings as 鈥渆quivocal鈥�, given that they are again
based on a small number of cases. But the fact that they come from a body
previously perceived as being sympathetic to the industry鈥檚 position that
mobiles are safe is bound to heighten public concerns.
WTR has also been investigating the effects of microwave emissions from
mobile phones on cultured cells. Most of these experiments have given negative
results, but Carlo says there is some evidence of genetic damage to human white
blood cells that increases with the radiation dose.
Epidemiologists say that the best hope of resolving the questions about
cancer lies in a pan-European study of some 3000 people with brain tumours,
which is just getting under way. This study, funded in part by mobile phone
companies but coordinated by the WHO, isn鈥檛 expected to yield results for
several years.