ANOTHER week, another less-than-convincing study on cellphones and cancer. This time the claim is that not only is there a link but that digital mobile phone users living in rural areas are three times more likely to develop malignant brain tumours than their urban counterparts.
The claim, by a team at 脰rebro University Hospital in Sweden, is based on a new analysis of data from an earlier study in which 1500 people with brain tumours and 1500 matched controls were asked about their cellphone usage, to see if there were any links with cancer risk. This kind of study is notoriously unreliable because it relies on people鈥檚 memories.
鈥淭hey didn鈥檛 rule out exposure to agricultural chemicals as a reason for the cancer risk鈥�
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The team says that one possible explanation for their finding is that mobiles emit stronger signals in rural areas, where base stations are more spread out. This is a reasonable theory, says Michael Clark at the UK鈥檚 Health Protection Agency, but not one this study proves. For instance, the study does not take into account the position and densities of base stations in relation to where the subjects live. Nor did the team rule out exposure to agricultural chemicals as a reason for the apparently increased cancer risk in rural areas.
Most damning of all is the fact that although it is ostensibly a large study involving nearly 3000 people, the headline conclusion of a threefold greater risk in rural areas is based on a subset of only 10 patients and just one control.
Clark points out that several large studies are under way. These studies, whose results are expected over the next few years, should help settle the issue of whether or not cellphones do increase the risk of cancer.
