No link between mobile phone use and brain tumours

The biggest ever study of its kind has shown there are no links between mobile phone use and the development of brain and central nervous system tumours, writes John Holden.

The number of people using mobile phones is rising every single day. Over five billion global subscriptions were made in 2010 alone. Naturally there should be some concern over any potential harmful effects technology this widely used might have on the population at large. One such concern has been links between radio waves given off from phones and the development of cancer in humans.

This old chestnut has been around for a while. But like radiation poisoning from microwaves or fluoride in the water “keeping us down”, a link between mobile phone use and the development of tumours in the brain or central nervous system appears to be another one of those myths that spreads with little or no basis in fact. (You might remember an old urban legend that went round about the late journalist Veronica Guerin. Reportedly a heavy mobile phone user, it was suggested that in the post mortem on her body they found developing tumours in her brain around the area where she had her phone up to her ear. It’s a rumour that has never been substantiated though.)

In what has been described as the “largest study on the subject to date”, Danish researchers at the Institute of Cancer Epidemiology in Copenhagen found no evidence that the risk of brain tumours was raised among 358,403 mobile phone subscribers over a period of almost two decades.

To date the only cohort study into links between mobile phone use and cancer, was a Danish nationwide study comparing cancer risk of all the 420,095 people who had signed a mobile phone contract from 1982 (the year such phones were introduced in Denmark) until 1995 with the corresponding risk in the rest of the adult population. This was then followed up again between 1996 and 2002. In both cases, the studies found no evidence of increased risk of any cancer among mobile phone users.

Researchers from the Institute of Cancer Epidemiology decided to continue the study up to 2007. Studying data on the entire Danish population aged 30 and over and born in Denmark after 1925, they subdivided them into mobile phones users and non-users before 1995. This infomation was gathered from Danish phone network operators and from the Danish Cancer Register. In all, they found 10,729 cases of central nervous system tumours in mobile phone users in the period 1990-2007.

When they limited the figures just to people with long term mobile phone use – 13 years or more - cancer rates were pretty much equal in both long-term users and non-users of phones.

The researchers say: “The extended follow-up allowed us to investigate effects in people who had used mobile phones for 10 years or more, and this long-term use was not associated with higher risks of cancer.  However, as a small to moderate increase in risk for subgroups of heavy users or after even longer induction periods than 10-15 years cannot be ruled out, further studies with large study populations, where the potential for misclassification of exposure and selection bias is minimised, are warranted.”

Ok so they’re leaving a caveat on their research – as all good scientists should - that they cannot rule out a small to moderate increase in risk of developing cancer for sub groups of heavy users. But overall a sample of 400,000 people over a twenty-year period showed there are little or no links. So can we put this one to bed now please?

Read the free, open source full text of the study here.

Image top: Annie Mole.