The International Agency for Research on Cancer just declared cell phones "possibly carcinogenic"—in the same category as DDT, engine exhaust, and coffee. Do you think cell phones are more like DDT and engine exhaust, or more like coffee? Is my cell phone going to give me a brain tumor?

Almost all of the studies looking into a link between cell phone use and cancer are crap. This is acknowledged outright in the IARC declaration. Keep in mind: Often it's easier to come to a solid conclusion with a small amount of high quality data rather than a mountain of crappy data. This declaration is based on a molehill of crappy data; prepare to lift a large grain of salt.

In fact, what's most interesting is what the declaration says cannot be shown with all the available data: a link between cell phones and any common cancer. Exposure—even high-level industrial exposures—to microwave radiation like that made by cell phones cannot be associated with any cancer. The only link, in this molehill of crappy data, is between self-reported cell phone use and two rare cancers: gliomas and acoustic neuromas. There was no dose response between cell phone use and these cancers—with more cell phone use, there was not a proportionate increase in possible cancer risk. (Finding a dose-response curve is a key hint that a correlation is actually causation—that the first thing is causing the second.) The lack of such a relationship indicates this is a weaker association than things like DDT or engine exhaust.

The increase in risk for these two cancers—gliomas and acoustic neuromas—was only about 40 percent. In the United States, there are about 10,000 gliomas diagnosed each year; a 40 percent increase would bump that up to 14,000. Acoustic neuromas are even more rare: Only about 3,000 cases are diagnosed in the United States per year. By comparison, there are about a quarter million people diagnosed with lung cancer each year in the United States. Even if this link is true—that cell phone use causes these two rare cancers—only a handful of the hundreds of millions of people who use cell phones will be affected. In contrast, for something like vehicle exhaust that is associated with a common cancer (lung cancer), a similar increase in risk would affect an enormous number of people.

This declaration, while scary sounding, is not based on any new data—rather a very cautious new interpretation of the existing data, and a plea for continued monitoring. The risk, in absolute terms, is low.

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