Mixed messages

By Michael Day and Kurt Kleiner 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 New Scientist investigated it last month (“Get your head round this…”, 10 April, p 20). The Swedish study of 209 people with brain tumours and 425 matched controls was led by Lennart Hardell at the Örebro 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 “phone ears”. The problem is that there were so few of these people—just 13—that Hardell and his colleagues can’t say for sure whether this was really linked to the patients’ 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. “This study doesn’t tell us much that we didn’t already know, other than that we need larger, more extensive studies,” concludes John Stather, the board’s deputy director. 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’s 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—compared with just 18 per cent of the controls. Carlo says this result is statistically significant, and should be followed up. “I want to make sure people know what’s being found,” he says. Carlo describes WTR’s findings as “equivocal”, 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’s 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,
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