Using the cell phone does not increase the risk of brain tumors, says Oxford study

To talk to a mobile phone, users place the device close to the head, the radiofrequency waves they emit penetrate several centimeters into the brain, with the temporal and parietal lobes being the most exposed. This has led to concerns that mobile phone users may be at increased risk of developing brain tumors, and the International Agency for Research on Cancer (IARC) classifies radiofrequency waves as “possibly carcinogenic.”

However, most of the studies that have investigated this question to date have been retrospective studies in which people report mobile phone use after a cancer diagnosis, meaning that the results may be biased.

Researchers from Oxford Population Health and IARC published in the Journal of the National Cancer Institute the results of a large prospective UK study (a study in the that participants sign up before they develop the disease (s) in question) that explores the association between mobile phone use and the risk of brain tumors.

The specialists used data from the UK's The Million Women Study: an ongoing study that recruited one in four UK women born between 1935 and 1950. Around 776,000 participants completed questionnaires on the use of their mobile phones in 2001; about half of them were surveyed again in 2011. Participants were then followed for an average of 14 years through linking to their NHS records.

The use of mobile phones was examined in relation to the risk of several specific types of brain tumors: glioma (a tumor of the nervous system); acoustic neuroma (a tumor of the nerve that connects the brain and the inner ear); meningioma (a tumor of the membrane that surrounds the brain); and tumors of the gland pituitary. Scientists also investigated whether mobile phone use was associated with the risk of eye tumors.

By 2011, almost 75 per cent of women aged 60 to 64 were using a mobile phone, and just under 50 per cent of women aged 75 to 79. During the 14-year follow-up period, only 3,268 (0.42%) of women developed a brain tumor.

That is, there was no significant difference in the risk of developing a brain tumor between those who had never used a mobile phone and mobile phone users. These included tumors in the temporal and parietal lobes, which are the most exposed parts of the brain. There was also no difference in the risk of developing glioma, acoustic neuroma, meningioma, pituitary tumors or eye tumors.

The research explains that radiofrequency electromagnetic fields—those emitted by mobile devices—can penetrate several centimeters into the head. The main effect of this is simply the heating of the skin surface. The article did not detect any increased risk of tumors in the temporal and parietal lobes of the brain, the areas potentially most exposed to these electromagnetic fields.

“These results support the cumulative evidence that the use of mobile phones in routine conditions does not increase the risk of brain tumors,” said co-researcher Kirstin Pirie of the Cancer Epidemiology Unit at Oxford Population Health.

The findings revealed by the study also did not demonstrate an increased risk of developing any of these types of tumors for those who used a mobile phone daily, talked at least 20 minutes a week, and/or had used a mobile phone for more than 10 years. And the incidence of right-sided and left-sided tumors was similar in mobile phone users, although mobile phone use tends to be considerably higher on the right side than on the left.

Although the findings are reassuring, it is not clear whether the risks associated with mobile phone use are different in those who use mobile phones considerably more than was typical among women in this cohort. E

In this study, only 18% of phone users reported talking on mobile phones for 30 minutes or more each week. Those who use mobile phones for long periods can reduce their exposure to radio frequency waves by using hands-free equipment or speakers.

The study did not include children or adolescents, but its authors point out that two months ago the results of an international research called Mobi-Kids - which analyzed the possible connection between cell phone use and the risk of brain tumors in young people from 14 countries - were released. The study, coordinated by epidemiologist Elisabeth Cardis, research professor in Radiation Epidemiology at the Barcelona Institute for Global Health, also found no evidence of a link.

“Mobile technologies are improving all the time, which is why more recent generations emit substantially less power output,” said the lead researcher of the study Joachim Schüz of IARC. However, given the lack of testing for large users, advising mobile phone users to reduce unnecessary exposures remains a good precautionary approach.

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