Reassuring results from first study on young mobile users and cancer risk

[NEWS, 28 July 2011] An international network of scientists, including researchers from Karolinska Institutet, has now published the first study on possible brain tumor risk and use of mobile phones among children and adolescents. The so called CEFALO study does not show an increased brain tumor risk for young mobile users. Nevertheless, the researchers emphasize the importance of further rigorous monitoring of brain tumor incidence trends in the next couple of years.

Various studies on brain tumor risk of adult mobile phone users showed no overall increased risk but inconclusive results regarding heavy mobile phone use. It has been hypothesized that children and adolescents may be more vulnerable to microwave radiation emitted by mobile phones than adults although a biological mechanism for carcinogenicity by low-dose microwave radiation is not known.

CEFALO is an international case-control study that was conducted among children aged and adolescents aged 7 to 19 years in Denmark, Norway, Sweden, and Switzerland. From these countries 352 youths diagnosed with a brain tumor between 2004 and 2008 were included in the study. Mobile phone use of these patients prior to diagnosis was compared with the mobile phone use of 646 randomly selected controls of the same age, gender and region of residence.

Young mobile phone users were not found to be at an increased risk of developing a brain tumor. Risk was not increased after five years or more since first use of a mobile phone. Tumors did not occur more often in the areas of the brain closest to where the mobile phone was held during making or receiving calls.

However, the researchers point out that the study has limitations and some uncertainty remains. Brain tumors are rare in this age group and average duration of mobile phone use was relatively short in the study sample. Pertinent to the interview-based case-control design, there is also uncertainty in the childrens recall of past mobile phone use. In a small subsample for which traffic records of mobile phone use from mobile phone operators were available a minor increased risk were observed. If this was a real association, there should have been an increased brain tumor incidence among children and teenagers overall in recent years  something that has not occurred.

"These results are reassuring given the extensive and worldwide use of mobile phones among children and adolescents", says Professor Maria Feything at the Institute of Environmental Medicine, who lead the Swedish part of the study. "However, it is important that we continue to monitor the incidence trends of sub-types of brain tumors by localization and histology using high quality cancer registry data, as even a small individual risk would result in a considerable number of additional brain tumor cases."

CEFALO is a collaboration of research groups in Sweden, Denmark, Norway, and Switzerland. The Swedish part of the study was supported by grants from the Swedish Council for Working Life and Social Research, the Swedish Research Council, the Swedish Cancer Society, the Swedish Childhood Cancer Society, and the Swedish Radiation Protection Authority.

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