Cancer isn’t calling

    22 November 2014

    I should preface this piece with a warning: I may be wrong. Perhaps, some day, greybeards will speak in dire tones of the Great Mobile Phone Plague of 2018. And they’ll speak of it, of course, through the lead-lined mouthpieces of phones splattered like cigarette packets with gory pictures of tumour-riddled brains and grim block-capitalled warnings that MOBILE PHONE USE KILLS.

    Perhaps. But very, very probably not.

    The idea that our mobiles could be killing us is scary. Within the past two decades, mobile phones have gone from being the playthings of City boys in red braces to a life essential as basic as wallets and keys. And there is something about the invisible cloud of electro-stuff that now surrounds us that people find unnerving. It is, after all, radiation, and we all know radiation is bad. So, every few years, the scare raises its head. The most recent outbreak came in May, when a French study apparently found that the people who used their mobiles most had a raised risk of some sorts of brain tumour.

    I first wrote about this in 2011, during an earlier outbreak which was sparked when the International Agency for Research on Cancer (IARC), part of the World Health Organisation, for the first time ruled on the risks of mobile phones and cancer. Disconcertingly, it placed them in a box marked ‘possibly carcinogenic’. Which sounded pretty bad.

    But looking closer, the headline — ‘WHO says mobile phones may cause cancer’ — was scarier than the detail. The IARC classifies things on a scale of one to four. Box 1 is the stuff that pretty much definitely causes cancer: smoking, alcohol, asbestos, sunburn. Box 4 is the stuff that ‘probably doesn’t cause cancer’, and to give you an idea of how careful the IARC is about putting stuff in that box, there’s only one thing in it: caprolactam, an organic compound used in the production of nylon. Box 3 is the stuff for which there’s no evidence either way. Box 2 is divided into two smaller boxes: 2A, ‘probably’ causes cancer, for when there’s good evidence from animal trials but not enough in humans to be sure; and 2B, ‘possibly’, when there is limited evidence even in animals, but it’s impossible to rule it out. I quoted Cancer Research UK (CRUK) saying at the time that ‘This group ends up being a bit of a catch-all category, and includes everything from carpentry to chloroform.’ And, as it turns out, mobile phones.

    Three years later the evidence remains weak, partly because lots of the studies, including the French one mentioned above, are ‘case-control’ studies: they speak to various people who either have or don’t have a particular kind of cancer, and question them about their mobile phone use over the last several years. The trouble with that is that people’s memories are faulty. Some studies found that the people who use their mobiles loads and loads have a higher incidence of some cancers — but one of those, a Danish study called InterPhone, was being told that those users were using their phone for five to 12 hours a day for ten years. It could well be that cause and effect is mixed up here: perhaps being told that you have a brain tumour makes you more likely to remember all the times you used your mobile phone.

    There is another kind of study, a cohort study, which follows a group of people for a number of years, reporting mobile phone use in real time and then measuring cancer incidence as it happens, which isn’t prone to that sort of problem. There have been two big studies of that kind recently; one called the ‘Million Women Study’ (it included, um, 790,000 women), and another Danish one of 420,000 people. Neither found any link between mobile use and any cancers at all; the Not-in-fact-a-Million Women Study at first thought there was a connection with a certain kind of tumour called an acoustic neuroma, but later ruled it out.

    The most compelling reason to believe mobile phones don’t cause cancer, though, is a simple one. In 1984, very few people used mobile phones; in 2004, most of us did, and now we pretty much all do. If they significantly raised the risk of brain tumours, or any kind of cancer, then you would expect a fairly sudden jump in the rates of those cancers. But brain tumour rates in Britain are pretty much unchanged since the 1980s and, CRUK says, the very slight rise is probably due to improved data collection. What’s more, there’s no plausible mechanism for how phones could cause cancer: yes, it’s ‘radiation’, but so is visible ligh, and the heat from your kettle.

    Of course, as is usually the case in health science, it’s very hard to rule anything out, which is why the IARC still has mobile phones in the ‘possibly’ box, and why CRUK says that research is ongoing. ‘Mobile phones are a relatively recent invention,’ the latter points out, and while we can be confident that there are no health risks within ten years, it’s not impossible that something may be lurking further down the line. But with every passing day that chance gets smaller, and it’s vanishingly small already. The Great Mobile Plague is, we can pretty much safely say, not coming.