By Sinead Carew
NEW YORK (Reuters) - Children and adolescents who use mobile phones are at no bigger risk of developing brain cancer than non-users, according to a study of patients aged 7 to 19.
The research, published in the Journal of the National Cancer Institute on Wednesday, addresses concerns that children may be more vulnerable to health risks from electromagnetic radiation of 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 cellphones -- found that brain tumor patients were no more likely to be regular phone users than control subjects who did not have cancer.
"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 several 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 cellphones are in use today, some 30 years after they were introduced commercially.
The World Health Organization (WHO) reignited interest in possible health risks from cellphones after it said in May that using a mobile phone might increase the risk of certain types of brain tumors.
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.
About 55 percent of the cancer patients reported regular mobile phone use compared with 51 percent 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 cellphone use.
LONGER TERM STUDIES NEEDED
In a subset of the study, Roosli's also examined information from mobile service providers about the length of the subjects' cellular subscription when available.
From operator data he found that the cancer risk had doubled for those people who had used phones from more than 3 years, but noted that this data was unreliable as more cancer patients had provided carrier records than control subjects.
Roosli's 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 tumors in brain areas most exposed to cellphone radiation.
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 tumor.
"(This study) provides quite some evidence that use of less than 5 years does not increase the chance of a brain tumor, but naturally we don't have a lot of long-term users," he said.
In an editorial published along with the article, U.S. 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 cellphones?"
(Reporting by Sinead Carew; Editing by Richard Chang)