This week all the buzz is about cellphones and brain tumors. Who would possibly link cellphones and brain tumors? The World Health Organization, that’s WHO.
This week, an agency in WHO announced that it was declaring cellphone use to be “possibly carcinogenic”, adding it to a group of substances which include lead, engine exhaust, chloroform, coffee and pickled vegetables.
First, let’s make sure we understand what this does not mean. This does not mean that cellphone use is known to cause cancer. The WHO classifies tobacco and ultraviolet light as known carcinogens, which is not the group in which it classified cellphone use. It also doesn’t mean that cellphone use is a probable carcinogen, like some industrial chemicals and exhaust from wood combustion. Probable carcinogens have another group in the WHO classification.
This means that cellphone use might cause cancer, or not. The WHO clearly announced that adverse health effects of cellphone use have not yet been established.
So what’s the hubbub? Well, so many people use cellphones that even if a cancer link is possible, the WHO wants to keep an eye on it. Naturally, media outlets were all over this story with various levels of alarm and skepticism (links below). There are two specific concerns that some studies have suggested: gliomas and acoustic neuromas. Gliomas are malignant brain tumors. Acoustic neuromas are benign tumors of the nerve that connects the ear to the brain.
But the studies have not been consistent. Dr. David Savitz, professor of epidemiology at Brown, says that most studies looking at cellphone use and cancer failed to show a link. (The quotes are in the articles linked below.) He also cites data from Scandinavian countries which were early in cellphone adoption and yet have not seen any increased incidence in brain tumors.
So there may be no increased risk at all, and this is all very vague and preliminary. But my regular readers know I like to dive into the numbers. If we believe the scariest of the studies, how risky would cellphone use be? Well, one study suggested that the risk of glioma doubles with every decade of cell phone use. Good grief! That sounds terrible. But before resigning yourself to sending messages by carrier pigeon from now on, let’s figure out the magnitude of that risk. There are 10,000 to 12,000 new cases of glioma per year in the US. Taking the upper figure, in the US population of 300 million that yields a risk of 1 in 25,000 of developing a glioma every year. That means that the risk over a decade is 1 in 2,500. If cellphone use over that decade doubles the risk, that means that for every 2,500 people using a cellphone for ten years one additional glioma results and the other 2,499 people go on blabbering on their cellphone.
Numerically, that’s a pretty small risk. That’s much smaller, for example, than the risk that untreated high blood pressure will lead to stroke. And that’s if there’s any risk at all which has not yet been proven.
So does it make sense to use Bluetooth or wired headphones during a call to keep our cellphones a few inches from our heads? I don’t know. There’s certainly no harm in that precaution, but there may also be no benefit. Compared to cellphones distracting drivers and causing traffic collisions, and people’s phones ringing in lectures and at movies, the possible cancer connection strikes me as tentative and minor.
But perhaps the WHO actually helped by giving us another excuse to end an unwanted conversation. “I gotta go. You’re giving me a brain tumor.”
LA Times article (including KTLA news video clip): Study links cellphones to possible cancer risk
CNN article (including video clip): WHO: Cell phone use can increase possible cancer risk
Wall Street Journal article: Cellphone Cancer Warning
CNN Health article: Coffee, pickled veggies also ‘possibly’ cause cancer
Yet again the nice folks at US Airways Magazine reprinted one of my posts – This Isn’t Your Father’s Heart Disease. If you missed it when I first wrote it, give it a read. And if you fly US Airways in June, please grab a copy.
Important legal mumbo jumbo:
Anything you read on the web should be used to supplement, not replace, your doctor’s advice. Anything that I write is no exception. I’m a doctor, but I’m not your doctor despite the fact that you read or comment on my posts.