Karolinska Group: No Brain Tumor Risk
The Karolinska group’s showing no increased risk of brain tumors among those who used a cell phone for ten or more years appears in the March 15 issue of the American Journal of Epidemiology. We first reported this in December based on a brief announcement from Stockholm, but the published paper offers many more details.
One interesting item is the finding of a somewhat elevated risk of developing a glioma (a 60-80% increase) on the same side of the head as the phone was used. But, the Karolinska researchers also saw a lower than expected glioma risk on the opposite side of the head. Stefan Lönn, Maria Feychting and Anders Ahlbom posit that these results don’t make sense. “It is not biologically plausible that RF exposure from mobile phone use would increase the brain tumor risk on the side of the head where the phone is usually held and protect against brain tumors on the other side of the head,” they write.
Lönn’s team previously among this same population of long-term phone users (both studies are part of his doctoral dissertation, and, in turn, they are part of the 13-country an increased risk of acoustic neuromasInterphone study coordinated by IARC in Lyon, France). For neuromas, there was no apparent protective effect on the opposite side of the head. All this means that the new paper, in their words, “strengthens the finding of an increased risk of acoustic neuroma.” The number of Swedes who used a phone for more than a decade is small, and so we anxiously await the results from other Interphone study groups. It is quite possible, however, that the Interphone study will not adequately resolve the neuroma risk. After all, the Scandinavian countries were quick to adopt mobile phones and some of the participating countries may have a smaller proportion of subjects who used them for more than ten years. The recent Stewart report (see our January 11 post) recommended more research, and made specific mention of a need for an international cohort study of mobile phone users. The editors of The Lancet endorsed this idea. Writing in the January 22 issue, they warned, “With more than one billion people, in more than 200 countries, now using a mobile phone, any risk, however small, could conceivably affect thousands of people.”