A major international study of a possible link between cell phone use and two types of brain cancer has proved inconclusive, according to a report due to be published in a medical journal Tuesday.
A 10-year survey of almost 13,000 participants found most cell phone use didn't increase the risk of developing meningioma — a common and frequently benign tumor — or glioma — a rarer but deadlier form of cancer.
There were "suggestions" that using cell phones for more than 30 minutes each day could increase the risk of glioma, according to the study by the World Health Organization's International Agency for Research on Cancer. But the authors added that "biases and error prevent a causal interpretation" that would directly blame radiation for the tumor.
Longer call times appeared to pose a greater risk than the number of calls made.
Among the factors that weren't examined were the effects of using hands-free devices during calls or the risk of having cell phones close by while not making calls.
The paper, which will be published in the International Journal of Epidemiology, was compiled by researchers in 13 countries including Britain, Canada, France, Germany and Japan, but not the U.S. Scientists interviewed 12,848 participants, of which 5,150 had either meningioma or glioma tumors. Almost a quarter of the $24 million required to fund the study was provided by the cell phone industry, though WHO said measures were taken to ensure the scientists' independence was protected.