The risk of cell phone usage—and now, the math

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Yesterday I told you that, when it comes to the recent news about cell phones and cancer, context is very important to understanding what the World Health Organization has actually said about your risk.

Today, Matthew Herper, a science and health journalist with Forbes, adds another important piece of information to this story—the math. While the majority of research done on possible links between cell phone use and brain cancer has turned up little evidence of a positive connection, there have been a couple of studies that give people reason to worry. So what happens if the majority of research turns out to be wrong, and those studies that do show cell phone usage might cause cancer are right? How would it actually affect individual risk?

The WHO said that the classification was mainly due to a study that showed heavy cell phone use might cause a 40% increased risk of glioma, a type of brain tumor. There are 22,000 cases of brain cancer in the U.S. annually, and a spokesman for the American Cancer Society tells me that 80%, or about 18,000, are glioma.

Now, 96% of the U.S. population, or about 300 million people, have cell phones. If everyone's risk of glioma went up 40% as a result of cell phone use, the number of gliomas in the U.S. would increase by 8,000. That's a one in 40,000 increase in each person's risk of glioma, which still isn't very big.

But the study the WHO is citing only showed the 40% increase in the 10% of people who used cell phones most. I don't know how many people in the U.S. would now fall into this group, but we'd be talking about maybe hundreds of cases spread out over the whole U.S. population.

If that still sounds scary, compare it to another cancer - one that I do find frightening. The number of cases of throat cancer caused by the human papilloma virus (HPV) is estimated to be about 11,300 now, increasing to 20,000 and beyond over the next few years as this infection spreads. That's a far scarier increase than if the glioma link for cell phones is true and everybody in the U.S. is talking on their phones nonstop. If we're going to worry about cell phones, we should worry about vaccinating boys for HPV.

This is not to say that if that one paper were correct (a big "if," considering the fact that there's been no documented increase in gliomas or other brain cancers, and no known mechanism for cell phones causing cancer, and other studies fail to find the same link between cancer patients and cell phone use ... but I digress) the increase in risk Herper calculates here would be acceptable. I think many people would probably agree that even a few hundred preventable brain cancers would suck, and would be worth taking some kind of action to prevent—whether through personal choice or regulation.* But the individual risk would still be very small. And there are other types of preventable cancer where the risk is similar (or even greater) and we've decided—collectively and individually—that we're OK with that level of risk.

In summary: The WHO announcement doesn't really tell us anything new; the evidence that cell phones might cause cancer is still very slim; and even if cell phones do cause cancer, the risk to you isn't particularly large. Whether you change the way you use your cell phone is up to you. But that's the information you need to have to make that decision.

*Insert trolls here.

Image: Hello Operator, a Creative Commons Attribution (2.0) image from derekolson's photostream