Children and adolescents who use mobile phones are at no bigger risk for brain cancer than non-users, according to a study of patients aged seven to 19.
The research, published in the Journal of the National Cancer Institute, addressed concerns that children may be more vulnerable to health risks from electromagnetic radiation from mobile phones.
Children's nervous systems are still developing, and there are fears that their smaller head circumferences could allow radiation to penetrate deeper into the brain.
But the study – the first to look specifically at children and the risk of cancer from cell phones – found that paediatric brain tumour patients were no more likely to be regular phone users than control subjects who did not have cancer.
WHO ignited interest
"If mobile phone use would be a risk factor, you'd expect cancer patients to have a higher amount of usage," said Professor Martin Roosli who conducted the study at the Swiss Tropical and Public Health Institute in Basel, Switzerland.
Funders of the study included groups such as the Swiss Research Foundation on Mobile Communication, which is partly supported by Swiss mobile operators. The funders were not involved in the study design or the collection, analysis, or interpretation of the data, according the authors.
About 5 billion cell phones are in use today, some 30 years after they were introduced commercially.
The World Health Organization (WHO) reignited interest in possible health risks from cell phones after it said that using a mobile phone might increase the risk of certain types of brain tumours.
Not much difference in use between cancer patients and control subjects
Roosli's research, conducted between 2004 and 2008 in Norway, Denmark, Sweden and Switzerland, looked at phone use of 352 brain cancer patients and 646 control subjects, all between the ages of seven and 19.
About 55% of the cancer patients reported regular mobile phone use, compared with 51% of the control subjects, according to the study.
"What we found was that there was no significant difference in the amount of use," Roosli told Reuters, adding that if there is a risk it would be a really small risk.
But since the study involved face-to-face interviews, Roosli acknowledged that he could not be certain of the accuracy of the subjects' recollection of past cell phone use.
Information from mobile services unreliable
In a subset of the study, Roosli also examined information from mobile service providers about the length of the subjects' cellular subscription, when available.
He found that the cancer risk had doubled for those youngsters who had used phones from more than three years, but noted that this data was unreliable, as more cancer patients had provided carrier records than control subjects.
Roosli said phone company records were not always available, as some people had changed their numbers and some operators were required by law to delete call records after six months.
The study found no evidence of any increase in the risk of tumours in brain areas most exposed to cell phone radiation.
Cell phone usage of less than five years not risky
Roosli said that future studies should examine longer term phone use among children. For example, he suggested collecting phone records from a bigger group to see who develops a tumour.
"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," he said.
In an editorial published along with the article, US scientists recommended that investigators continue to monitor population incidence rates.
In the meantime, they said, people who are concerned should consider using an ear piece or the phone's speaker function.
Asked about practices in his own family, Roosli said "our study does not provide strong evidence of a relation, so why should I forbid my children from using cell phones."
(Reuters Health, July 2011)