Mobile phones and cancer. Again

(H/T @DickMandrake)

This will be all over the papers today, so here’s a quick run down of what’s actually happened.

Last year the World Health Organisation released its Interphone report (PDF) into the link between brain cancer and mobile phones. For the most part, they found “no increase in risk of glioma or meningioma [types of brain cancer] was observed with use of mobile phones”. However, for very heavy users (the top 10% of the population), there was a statistically significant increase in the odds of developing a form of brain cancer known as glioma but “but biases and error prevent a causal interpretation” – there is too much uncertainty in the data to know whether heavy mobile phone use caused cancer or whether something else was to blame. On the one hand, they found there appeared to be a connection between which side of the brain the tumour developed in and which hand users held the phone in – a sign that phones might cause cancer – but on the other hand, while extreme users experienced a big increase in brain tumours, people who used their phones even slightly less saw no change in brain cancer – a sign that mobile phones might not cause cancer.

Fast forward a year, and the WHO’s International Agency for Research on Cancer (IARC) has issued a press release (PDF) about an upcoming report which, based on the Interphone study and some other papers, will classify the electromagnetic (EM) fields from mobile phones as “possibly carcinogenic to humans” meaning there is “limited evidence” that they may cause cancer. In other words, it’s the exact same conclusion as the Interphone report, but this time the report is focusing on the negative – heavy doses may cause cancer – rather than the positive – light doses probably don’t cause cancer.

That in itself is very reasonable – even if mobile phones carry a very slight cancer risk, the IARC still need to know what that risk is. The problem comes when the media, reporting this in the usual shades of black and white, ignore all this nuance in favour of scares:

The Mail screams “Mobile phones CAN increase risk of cancer: Doctors reveal shock results of major study into effect on the brain“, magically turning “possibly causes cancer” into “CAN cause cancer”. It’s not really a shock result either, since it came out a year ago. The Mail also brings up the recent Council of Europe draft report that suggested banning mobiles from around schools, ignoring the fact it was pseudoscientific rubbish based on research from quacks.

The Express goes for the similar “Shock cancer warning over mobile phone use“, claiming “MOBILE phones have been officially linked to cancer for the very first time by a team of world experts”. Again, the report is a year old, it’s not a shock! They also manage to get in some ridiculous guilt-by-association:

But they classified mobile phones in the same danger category as the pesticide DDT and petrol engine exhaust, meaning they are possibly carcinogenic to humans.

Petrol exhaust and DDT are pretty dangerous, but that’s not necessarily because they cause cancer! Nor does being in the same group as these mean it carries the same risk of cancer, either. It just means that we have the same level of evidence for a cancer risk, which isn’t the same thing. For example, DDT is now banned worldwide, with most developed countries banning it in the 70s. This means that people aren’t being exposed to it any more (a good thing, of course!), so we can’t study its effects and work out exactly how dangerous it is.

The Guardian meanwhile goes for a tenuous connection to the risks of mobile phone base stations and wi-fi, even though the exposure to EM from these is much lower than from holding a phone to your ear – and we know even then it’s only the heaviest exposures that may cause cancer.

The Telegraph also makes the ridiculous DDT comparison, but at least they quote the great Ed Yong, head of health information at Cancer Research UK, who sensibly sums up the evidence:

“The risk of brain cancer is similar in people who use mobile phones compared to those who don’t, and rates of this cancer have not gone up in recent years despite a dramatic rise in phone use during the 1980s.

“However, not enough is known to totally rule out a risk, and there has been very little research on the long-term effects of using phones.”

(They also quote a professor of Medical Physics and Director of the Mobile Operators Association, but to be honest, they seem to have gone into damage control mode before there’s been any damage to control. Pro-tip, guys – if you ever end a paragraph about the health risks of something by saying “The social and technological benefits also need to be emphasised“, then you sound like a cyberpunk bad guy, even if you truly mean it.)

Anyway, for a little perspective, there’s a great interview with Ed Yong about the news here. Read it!

Edit: There are also great pieces out there on this from Pharyngula, Respectful Insolence, Cancer Research UK, Tom Chivers, Only That In You, Scientific American and Bad Astronomer. Good old blogosphere!