It’s become one of those oft-repeated half-truths floating around that people either assume to be unerringly true or completely false. It draws both sides of the spectrum: those that eschew all traditional medicine, and the folks who take the official governmental recommendations and proclamations as gospel, every single time. Every now and then, you might hear a blurb about the cell phone-cancer connection on Oprah, or on the evening news, or from the neo-hippy mother picking up her child from daycare. You probably can’t really quite place where you first heard about it. It’s just there, lingering in the public mind space. And it never really gets a clear answer. Now, a growing body of research seems to suggest that a link between cell phone usage and brain tumor incidence does exist, but it’s just that: an association, a correlation. Correlations are interesting, but you can’t draw concrete causal conclusions with correlations alone (Ancel Keys’ dietary fat graph, anyone?).

We remain stuck with ambiguous links and suggestions. Is there evidence of a causal link between cell phone usage and the incidence of brain tumors? Do scientists offer an actual mechanism that theoretically explains the brain’s susceptibility to tumor growth when exposed to cell phone radiation?

I’m going to spoil the ending before I really get started. No, it hasn’t been proven, and while the correlative data has only gotten stronger, a possible mechanism for causation has not been established. One study showing correlation is pretty meaningless. Five studies showing the same correlation warrants further investigation, but they’re still essentially meaningless. But once you get into the realm of eleven, or even twenty-three studies all suggesting a correlative link between cell phone use and brain tumors, things change. It still doesn’t prove anything in the way of causation, but it can make for some serious hypothesizing. And it definitely legitimizes a closer look.

In September of this year, researchers from the Australian National University took a closer look. They conducted a review of eleven long-term studies examining a possible link between cell phone usage and brain tumors. In order to be eligible for consideration, each study had to satisfy certain requirements: publication in a peer-reviewed journal; study participants with a minimum 10-year history of cell phone usage; and a focus on “laterality,” or whether using a cell phone on a particular side of the head resulted in greater tumor development on that side. These were long-term studies with some fairly rigorous standards, and the authors of the meta-analysis concluded that “there is adequate epidemiologic evidence to suggest a link” between cell phone usage and brain tumors. No causation, but it began to look like something was going on.

The inquiry continued in October, when another team of researchers conducted a similar meta-analysis of 23 eligible studies. They too found “possible evidence” that mobile phone usage exceeding ten years may be linked to an increased risk of brain tumors, concluding that further cohort studies are needed to confirm hard evidence of a causal effect. These guys also found a connection between which side of the head a user typically held the phone and which side of the head developed tumors – if that correlation doesn’t inspire a bit of hypothesis formation, I don’t know what possibly could.

The media is taking notice. CNN discusses the associations between cell phones and cancer in a recent article, but to their credit, they avoid any bold, definitive pronouncements. Epidemiology suggesting actual links between two variables (red meat intake and mortality, for example) is usually instant fodder for the media’s insatiable desire for sensationalist “news” stories, so I was halfway expecting the coverage of the subject to boldly proclaim, “Cell phones cause brain cancer!” CNN does mention the October 23-study meta-analysis, and notes that the stronger, more scientifically rigorous studies showed the greatest link between cell phones and cancer, while the weaker studies, some of which actually suggested a protective quality, were funded by telecommunications industry groups.

The debate rages on, but there is one incontrovertible truth: cell phones do emit an electromagnetic field that penetrates the head. Cell phone radiation is not ionizing – that is, it doesn’t detach electrons from atoms or molecules and shake them around and cause havoc, as do x-rays or radioactive materials – but it is similar to microwave radiation. Skeptics counter that although cell phone radiation is classified with microwave radiation, since it isn’t powerful enough to damage DNA or heat up tissue (like sticking your brain in a microwave), there’s no danger. No short-term danger, sure. It’s never been shown that cell phone usage instantly produces brain damage (although you wouldn’t know it from the way some users behave in public or in transit), but that’s never really been the issue. The real issue is long-term, incremental damage over a lifetime. Does it exist? Does the correlation imply causation?

Two UK papers report that the upcoming release of the World Health Organization’s decade-long Interphone study on heavy cell phone use and brain cancer will show a significant increase in brain cancer following a decade of regular cell phone use – about an 18% increase, with the majority of those cancers developing on the same side of the head users hold their phones. Hmm. 18% over ten years? Sounds like a massive increase, especially for something as serious as brain cancer. But when you consider the relative rarity of a condition like brain cancer, 18% doesn’t sound so bad. According to an article by Scientific American, men and women worldwide have a 1 in 29,000 and 1 in 38,000 chance, respectively, of developing brain cancer in their lifetimes. Even if a study indicates that heavy cell phone users have three times the risk of developing brain cancer, that would mean a man’s chances over 60 years would jump from 0.206% to 0.621%, and a woman’s from 0.156% to 0.468%.

My hunch is that basic cell phone use isn’t a huge issue, and brain cancer is such a rarity that using your phone once or twice a day isn’t going to ensure a tumor. If you’re going to stress about the electromagnetic field emitting from a cell phone, where do you stop? What about the steady hum of electronics all around us? Wi-Fi? I look at like this: contemporary life, with all its trappings and tech and comforts and electromagnetic fields, is here to stay. You can mitigate its effects by eating a healthy diet, exercising regularly, getting plenty of sleep, and wearing a Bluetooth headset or holding the phone away from your head, but unless you live completely off the grid, you’re going to expose yourself to unnatural, perhaps unwanted environmental effects. And even if you live a hundred miles from the nearest sliver of civilization, it’ll still probably find you.

I’ll still recommend that people keep the cell phone usage to a minimum, but not to necessarily avoid brain cancer. Perhaps a better reason is that too often cell phones become prisons preventing us from truly engaging with the world. Time is ever moving, and technology is only going to progress – it may soon become a rare and precious moment that we’re able to dwell silently on our thoughts without wireless signal or electromagnetic field or peripheral cell phone chatter intruding.

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