Ordinary mobile phone use does not cause brain tumors, according to a study of hundreds of thousands of people that could finally lay the matter to rest after more than two decades of speculation and fear.
Researchers have gone further than at any time since concerns were first raised in the 90s in saying that for the vast majority of people, mobiles do not pose a cancer risk.
It means the World Health Organization’s International Agency for Research on Cancer (IARC), which had previously declared mobile phone use as “possibly carcinogenic”, has now concluded that for the average user the devices are safe.
It also says that there is no evidence heavy users – those who make calls with the phone pressed against the head for about seven to 10 hours a week or more – are at risk. However, it cannot yet rule out the possibility.
The data come from a landmark British study composed entirely of women participants.
“For ordinary use, I think we have strong convincing evidence that mobile phone use doesn’t cause problems – while for the smaller group of people with very heavy use, we would give some precautionary advice. But overall we have the situation pretty much under control,” lead researcher Joachim Schüz, of the IARC, told I.
“This is an important study that builds on previous research. The longer you are observing people the more robust the data becomes. Every new study is a piece of the puzzle.”
Dr Schüz has stopped short of giving the all-clear for heavy mobile use because the study only looked at women, while very heavy users tend to be men. As such, the sample size was too small to draw definitive conclusions about heavy use.
There is no evidence to suggest heavy users are at risk, but the researchers nontheless advised them to adopt the precautionary principle and use speakerphone or headphones where possible to minimize the contact their gadget has with their head.
The researchers used data from the Million Women Study: a huge ongoing research project which has recruited one in four of all UK women born between 1935 and 1950.
Around 776,000 participants completed questionnaires about their mobile phone usage in 2001, and about half of these were questioned again in 2011. The participants were then followed up for an average of 14 years through linkage to their NHS records.
“These results support the accumulating evidence that mobile phone use under usual conditions does not increase brain tumor risk,” said Kirstin Pirie from Oxford University’s Population Health department, who also worked on the study.
Since mobile phones are held close to the head, the radiofrequency waves they emit penetrate several centimeters into the brain, with the temporal and parietal lobes being most exposed. This has led to worries that mobile users might be at an increased risk of developing brain tumours,
Previously, the IARC had classified radiofrequency waves as “possibly carcinogenic”, based on earlier concerns and in the absence of much science on the subject.
The fears were reignited more recently by the launch of 5G technologies.
The evidence from the latest study debunks these theories.
Karis Betts, health information manager at Cancer Research UK, said: “It’s a persistent myth that mobile phones or the signals they put out cause cancer. The results of this large study provide more evidence to say it’s just that – a myth.”
Professor Malcolm Sperrin, of Oxford University Hospitals, said: “This study from Oxford is a welcome addition to the body of knowledge looking at the risk from mobile phones. There is always a need for further research work, especially as phones, wireless etc become ubiquitous, but this study should allay many existing concerns.”
Dr Michael Jones, senior staff scientist in genetics and epidemiology at The Institute of Cancer Research, London, said: “This study supports the accumulating evidence that mobile phone use under usual conditions does not increase risk of brain cancer.”
Dr Schüz noted that mobile phone technologies were improving all the time, so that the more recent generations use much less power than in than they used to, reducing any risk that there might be to heavy phone users.
The study is published in the Journal of the National Cancer Institute.