A EUROPEAN study involving nearly 1000 participants has found no link between mobile phone use and brain tumours in children and adolescents, a group that may be particularly sensitive to phone emissions.
The study, published in the Journal of the National Cancer Institute, was prompted by concerns that the brains of younger users may be more vulnerable to adverse health effects — such as cancer — from mobile phones.
In the past two decades, mobile phone use has soared among children in developed countries, with one study suggesting that most youths start to use mobile phones by age 9 or 10. Children have a developing nervous system, and cellphone emissions penetrate deeper into their brains. Studies have indicated that the outer brain tissue of children ages 5 to 8 may absorb twice the amount of cellphone energy absorbed by adult brains.
Public health data indicate no increase in brain tumours among children in the US and many parts of Europe, whether from cellphone usage or any other cause. The latest research “shows that a large and immediate risk of mobile phones causing brain tumours in children can be excluded,” said Martin Roosli, lead author of the study and an epidemiologist at the Swiss Tropical and Public Health Institute in Basel.
After two decades of research, there’s little evidence conclusively linking mobile phone use in adults to major health problems, such as the development of brain tumours.
A 13-country study of adults, released last year, suggested that there was no increased brain-cancer risk for mobile phone users compared with non-users. However, the heaviest users appeared to have a slightly increased risk of a certain type of brain cancer.
In May, based on a review of existing science, the World Health Organisation announced that mobile phones were “possibly carcinogenic” to humans. Yet even that technical classification didn’t specifically link mobile phone use to cancer. Instead, in the WHO’s own words, it meant that while a link had been observed, “chance, bias or confounding (factors) could not be ruled out with reasonable confidence.”
The children’s study, based to a significant extent on self-reported data, has limitations. The subjects had been using their phones only for an average of about four years, which may not be long enough to ascertain cancer risk. Plus, the time they spent on voice calls — where the phone is held to the ear — was relatively small. Many children use their phones primarily for text messages, rather than calls.
Because of these limitations, and because mobile phone usage continues to increase, “we should still keep an eye” on any possible health effects in children, said Dr Roosli.
Mobile phones emit non-ionising radiation, which has enough energy to cause atoms in a molecule to vibrate, but not enough to remove electrons. Sound waves and visible light waves are other examples of non-ionising radiation.
Animal studies have suggested that mobile phone emissions aren’t strong enough to directly damage DNA. But fears of such a risk remain, both for adults and for children.
Dr Roosli and his colleagues studied mobile phone usage in 352 people ages 7 to 19 who had been diagnosed with a brain tumour between 2004 and 2008. They also looked at mobile phone use by 646 control subjects drawn randomly from the general population but who matched the first group by age, sex and geographical region.
The subjects in both groups were quizzed about how often they used their phones for voice calls. The researchers also obtained usage data from wireless providers, when it was available. The study was conducted in Norway, Denmark, Sweden and Switzerland.
The scientists concluded that regular users of mobile phones weren’t more likely to have been diagnosed with brain tumours than non-users. Other observations showed no increased risk of tumours for brain areas that received the most exposure.
Kurt Straif, a cancer epidemiologist at the WHO’s International Agency for Research on Cancer who wasn’t involved in the latest research, said the study was “important” because it was the first to look at a possible mobile phone and brain cancer link in children.
But the study could be hobbled by a problem. “Participants with brain cancer may not have the best recall for how often they used their phones,” said Dr Straif. The researchers weren’t able to use billing records to precisely document the phone usage of study participants.