Children and teens who use cellphones are not at a statistically significant increased risk of brain cancer compared with their peers who do not use the devices, a study published Wednesday suggests.
Researchers from the Swiss Tropical and Public Health Institute in Basel, Switzerland, studied data collected in Norway, Denmark, Sweden and Switzerland.
The team looked at the medical records of 352 children aged 7 to 19 who were diagnosed with brain tumours between 2004 and 2008. The study also included 646 control subjects.
They found that 265 patients (75.3 per cent) and 466 control subjects (72.1 per cent) reported having spoken on a mobile phone more than 20 times prior to when the case patient was diagnosed with a tumour. Also, a slightly higher proportion of tumour patients versus control subjects — 55 per cent against 51 per cent — reported regular cellphone usage. But these differences were not statistically significant.
Risk not related to amount of use
In a subset of study participants for whom data was available from their cellphone company on their mobile usage, brain tumour risk was not found to be related to amount of use.
No increased risk of brain tumours was observed for brain areas receiving the highest amount of exposure.
The study is published in the Journal of the National Cancer Institute. Because it was not a randomized control trial, it shows correlations only and cannot definitively rule out a causal link between cellphone use and cancer.
Still, researcher Martin Roosli said no previous paper has examined whether cellphone use among children and teens is associated with a difference in brain tumour risk.
"Because we did not find a clear exposure-response relationship in most of these analyses, the available evidence does not support a causal association between the use of mobile phones and brain tumors," Roosli and his fellow researchers write.
"[This study] provides quite some evidence that use of less than five years does not increase the chance of a brain tumour, but naturally we don't have a lot of long-term users," Roosli told Reuters. If there is a risk, "it would be a really small risk," he said.
However, the researchers still advise a "careful watch" of the trend that has seen cellphone use increase among children over the years.
Two years ago, a number of government agencies around the world suggested that anyone who uses a cellphone should keep a little distance between the phone and their body. Britain, Germany, Belgium, Israel, Russia and India advised that children limit their use of cellphones. Health Canada gave no such advice, saying there is "no convincing evidence" of an increased cancer risk from exposure to radio frequencies from cellphones.
At the time, Finland's Radiation and Nuclear Safety Authority — citing a lack of research — encouraged parents to err on the side of caution and limit the time their children spend on cellphones.
The bulk of research into cellphones has found no definitive evidence that short-term use poses significant health risks to humans.
The new Swiss study was funded in part by the Swiss Federal Office of Public Health and the Swiss Research Foundation on Mobile Communication. The latter is partly supported by Swiss mobile operators, but the researchers say those funding the study were not involved in its design or the collection and interpretation of data.