When I was reporting my March 2010 PopSci feature story on the possible health effects of cell phone radiation, I was particularly interested in learning about the Interphone project, a collection of 13 different national studies coordinated by the International Agency for Research on Cancer (IARC), part of the World Health Organization.
Interphone is the largest completed analysis to date of brain tumor (glioma and meningioma) risk in relation to mobile phone use. When I was writing my piece, none of the scientists I interviewed could or would say much about the study, since it had yet to be published. So not much about Interphone ended up in my story. But when I asked one source familiar with the study’s progress what we would learn once the results appeared, this person said: “We’ll learn how to do better studies.”
Well, the Interphone study has finally appeared and, unfortunately, my source was right.
The paper, published this week in the International Journal of Epidemiology, concludes: “Overall, no increase in risk of either glioma or meningioma was observed in association with use of mobile phones. There were suggestions of an increased risk of glioma, and much less so meningioma, at the highest exposure levels … However, biases and errors limit the strength of the conclusions we can draw from these analyses and prevent a causal interpretation.”
This result is in line with the majority of other published studies, which also observed no increased risk of brain tumors in association with cell phone radiation and cite biases and errors in those studies that do show a correlation. But the publication of the Interphone results does not address the two main concerns of those who believe cell phone radiation may have an impact on human health: namely, that the effect of long-term exposure, especially on children, is still unknown and that brain tumor rates alone are not the proper metric by which to measure risk.
Methodological failings—especially recall bias; i.e. people incorrectly remembering past cell phone use—have long plagued research on this topic. The Interphone authors once again cite bias as preventing any firm conclusions about the effects of long-term use: “The possible effects of long-term heavy use of mobile phones on risk of brain tumors require further investigation,” the paper states, “given increasing mobile phone use, its extension to children and its penetration world-wide.” To that end, the IARC will carry out a comprehensive review of all published epidemiological and experimental evidence and the European Union will fund MobiKids to investigate the risk of brain tumors in childhood and adolescence.
Studies like Interphone and MobiKids take a long time to conduct and, of course, by the time they are finished the technology has already moved on, which raises doubts about the usefulness of the results. Since Interphone was launched, for example, cell phone usage has increased dramatically but radiation levels from cell phones have decreased.
Plus, the scientists who believe there could be a risk from cell phone radiation believe that risk could involve the immune system as a whole rather than a direct cause-and-effect relationship between radiation and brain tumors. So many of these scientists suspect studies like Interphone don’t give the full picture.
One thing is clear, though: After Interphone, opinion will be just as polarized and passions will run just as high as before Interphone.
Browse through some of the comments posted to my original story for a taste of the debate. Many people ridiculed the very idea of risk from cell phone radiation, and accused Per Segerbäck, a Swedish former telecoms engineer who suffers from electro-hypersensitivity (EHS) and whom I profiled in the piece, of inventing his condition. Several EHS sufferers wrote back, explaining their condition and citing studies that suggest it’s real.
Segerbäck’s daughter even responded with a comment of her own: “Maybe you never heard anyone say anything bad about your dad, but … reading you comments made me cry … I’m sorry if you don’t understand the illness, but I promise you that a lot of people has it. But please do not think that he is just making this up. That breaks my heart.”
I do not believe Segerbäck invented his condition, but I am not able to cite a study that provides a scientific explanation for it either. There is evidence to suggest possible mechanisms for a health effect from cell phone radiation; these are outlined in my story. None of the scientists who did this research and whom I interviewed for my story said their work ‘proved’ that cell phones have an impact on human health. They all did say, however, that the evidence merited further research—which is exactly what the IARC is saying.
Research into the potential health effects, if any, of cell phone radiation is so hotly contested in part because the technology is relatively young, but also because the research itself is so difficult to carry out.
I don’t know if cell phone radiation has an effect on human health, but I do know it’s not good science to dismiss the unproven as impossible. In fact, we could do a lot worse than to take Segerbäck’s own advice: “Be careful, weigh the evidence, and make your own decision.”