Publication of a landmark study into mobile phones and brain cancer was delayed for years because scientists failed to agree on its findings and whether to issue a warning about excessive use of the devices, the Guardian has learned.
The World Health Organisation's Interphone report was due to be published in 2006, but was held up until Monday because scientists from 13 countries interpreted the results differently. In the study, more than 5,000 men and women with brain tumours, and a similar number of healthy controls, were interviewed about their mobile phone use. Scientists then looked at whether those who had been diagnosed with tumours used their phones more.
The interviews found no solid evidence that mobile phones increased the risk of brain tumours, but pointed to a slightly greater risk among those who reported using mobile phones the most. According to the study, the 10 per cent who used their phones the most, racking up at least 1,640 hours of calls, had a 15 per cent greater risk of meningioma and were 40 per cent more likely to develop glioma. These are the two most common brain cancers, although still exceptionally rare, affecting less than seven in 100,000 people in Britain. The most frequent mobile phone users were also more likely to have a tumour on the same side of their brain as the ear they put their phone too, the study found. There were disagreements about the severity of flaws in the study, some of which could have led to an artificial rise in cancer risk among the most frequent users. People are poor at remembering for how long they have been on the phone, and only slightly better at remembering how many calls they made. Some participants claimed they used mobiles for more than 12 hours a day, a figure that skewed the results but is unlikely to be true.
Another confusing aspect of the study was that it appeared to show that modest use of a mobile phone actually reduced the risk of brain cancer. The effect may be false and due to volunteers in the control group being healthier than the general population or otherwise unrepresentative. “We had to find a version everyone could live with,” said a researcher. Two appendices that were published online, but not with the main Interphone study, claim the risk of tumours may be higher than the report claims. As yet, scientists know of no mechanism by which mobile phone radiation could cause cancer. — © Guardian Newspapers Limited, 2010
