U. LEEDS (UK)—Results from the largest epidemiological study of mobile phone use to date shows no link between mobile phones and brain tumors.

The study, published in the International Journal of Epidemiology, combines information from the 13 countries that took part in the study and focuses on the two main types of brain tumor: glioma and meningioma.

“Overall this research has not shown evidence of an increased risk of developing a glioma or meningioma brain tumor as a result of using a mobile phone. This is consistent with published biological studies, which have not established any effect of exposure to radiation from mobile phones at a cellular level nor found a mechanism by which cancer could be caused,” says Patricia McKinney, epidemiologist at the University of Leeds and leader of the U.K. North part of the Interphone study.

Interphone was conducted between 2000 and 2004 and was coordinated by the International Agency for Research on Cancer. The work was carried out in 13 countries, with much the largest contribution coming from the U.K. Results from individual countries, including the U.K., have been published previously but this is the first time that data from all 13 countries has been analyzed together.

A total of 2,708 men and women aged 30-59 years with glioma and 2,409 with meningioma, and matched adult controls without a brain tumor, were interviewed about their mobile phone use. Participants were asked about when they started using a mobile phone, how many times per day they used their phone, and how long the calls were.

The study found no overall increase in risk of glioma or meningioma brain tumors in regular users of mobile phones. Indeed regular users had an apparently decreased risk, although this decrease seems likely to be an artifact of the study methods and not a real effect from using a mobile phone.

No relationship was found between the risk of a tumor and the number of years people had been using mobile phones; risks were not raised for people who had used mobile phones for the longest category analyzed—10 or more years.

For the estimated total (cumulative) hours of phone use there was an apparently increased risk of glioma seen in the highest ten percent of users. However, some of these had reported improbable levels of use, for instance 12 or more hours every day; there was no trend of increasing risk with greater phone use for people in the nine lower use categories; and there was no relation to risk for the cumulative number of phone calls made. These factors suggest that the apparently increased risk with the highest cumulative hours of use cannot be interpreted as evidence of mobile phones causing brain tumors.

Subjects were asked the side on which they had used a phone, but no conclusion about brain tumor causation could be drawn from this because their recollection and reporting of the side of use may well have been biased by their knowledge of the side that their tumor occurred.

“Interphone is by far the largest study of its type to date. The balance of evidence from this study, and in the previously existing scientific literature, does not suggest a causal link between mobile phone use and risk of brain tumors,” says Anthony Swerdlow, an epidemiologist at the Institute of Cancer Research and leader of the U.K. South part of the Interphone project. “The duration of phone use for which we yet have evidence is currently limited, however, and we have virtually no information for use of mobile phones for longer than 15 years.”

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