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


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


  1. The media response to this is very much like the media response, almost 50 years ago, to studies that showed cigarettes caused cancer. The Tobacco Industry bought a lot of ads in print and broadcast media so media was motivated to protect them and the income stream they produced. In the same way present media, even boingboing, is motivated to protect the media stream that comes from ads for cell phones, cell phone plans and cell phones apps. Plus the fact that a lot of people love their cell phones as much as anyone ever loved their cigarettes. So… denial. Don’t worry, be happy.

    I remember chiding someone for smoking, telling them it would give them cancer and kill them. They answered back, jokingly, that they would rather die than give up cigarettes. Then about five years later they did die of lung cancer. In the same way people would rather risk dying of cancer than give up cell phones, rather slowly cook part of their brain than give them up. But when the time comes to die I wonder if it will have been worth it to them.

    1. You seem very certain that you are right and the science is wrong. Mind if I ask why? Because you don’t say in your comment; you just take it as a given that phones cause cancer.

      I would say that it is certainly not a given for most people. And certainly not for the WHO, or they would not have given it a measly 2B…

      1. Alllie did not say that cell phones cause cancer. You inflated her cautionary stance (which is based on WHO’s observation that there are some indications that cell phone use is correlated with increased cancer risk) and created something that she did not actually say.

        That is exactly the tactic of the Tobacco Institute, so I think you proved her point very well.

      2. You seem very certain that you are right and the science is wrong. Mind if I ask why? Because you don’t say in your comment; you just take it as a given that phones cause cancer.

        I’m sure the science is right and those that make money from cell phone ads or who just love their cell phones are wrong.

        1. “I’m sure the science is right”

          The science currently says that cellphones are safe, but that we could do with more research.

      3. a “measly” 2B?

        Would you leave an open container of carbon tetrachloride on your nightstand? How about DDT, would you let me powder your pillow with DDT? They’re such ‘measly’ threats to health.

        also, I agree with allie. The only reason you care is either a) you’re financially involved or b) you really like your phone and you’re just deeply self-involved. I suspect B is the case.

        1. Would I like some DDT sprinkled on my pillow? Hmm, given that I’m not female and don’t much care about my future fertility, then I’d have to say *if there was a reason to put DDT on my pillowcase*, I’d do it.

          Thanks for causing me to read up on DDT, I haven’t done that since high school chemestry.

          Come to think of it, DDT is supposed to be effective against bed bugs. If this current ‘epidemic’ of them goes on, maybe we’ll have a chance to test your idea.

        2. “Would you leave an open container of carbon tetrachloride on your nightstand? How about DDT, would you let me powder your pillow with DDT?”

          No, but I often have an open container of coffee. And I doubt I would want to smear my pillow with pickled vegetables — but I doubt it would do any harm, either.

          “The only reason you care is either a) you’re financially involved or b) you really like your phone and you’re just deeply self-involved. I suspect B is the case.”

          Unless you’re telepathic, don’t pretend to know what my motivation is. If you are telepathic, stay the f*** out of my head. (Clue: you’re not.)

        3. My objections to inhaling carbon tetrachloride have nothing to do with any cancer risk. I’d be far more worried about it dissolving my kidneys and tossing me into a coma that leads to my death. Similarly, my objections to having any pesticide on my pillow isn’t because I’m worried about cancer and more because pesticides, by their very nature, are toxic. Again, cancer isn’t the real concern. And as pesticides go, DDT is one of the better ones to be scattering around.

          The reason I care is because I don’t like seeing actual science coopted for media scares and I despise baseless fearmongering.

      4. Well, I remember hearing, on This American Life, I think — look it up if you have time — a segment with a person who had done a great deal of research into the research and discovered (from my sketchy memory now) that of the research done with funding from the cellphone industry 25% of the studies found some evidence of a link between cellphone use and cancer. Of the research without funding from the industry 75% of the studies found such evidence. He also alleged that there was a point when the US government (military) wished greater use of cellphone and cellphone-like technology and basically removed public funding from cellphone/cancer research effectively drying up funding for such research in the US which is why most is done elsewhere.

        Just because it is science doesn’t mean that there is not something else going on behind it. I use a headset with a wire. Seems like the Precautionary Principle could be wise here. Seems like one more example of techno-hubris to say it is nothing to worry about. Just sayin’…

    2. Hmm, the main media response to this study so far *has been* “OMGWTFBBQ cell phones cause cancer!” and not denial as your comparison suggests. BB (and a few other more technically competent news sources) are the sea walls against that ‘vast wave of stupidity’.

  2. Whenever I read a science-related announcement in the news these days, my first thought is always “I wonder what Maggie’s take is on this”.

    Thanks for helping cut through the crap. You are a lighthouse of reason in a churling ocean of stupidity.

    1. Great. Now I have to figure out how to put “a lighthouse of reason in a churling ocean of stupidity” on my business cards without coming across as an asshole. Thanks. ;)

      1. Make it visual. A lighthouse, with your face on it, smiling out on an ocean of Glenn Beck heads?

        Hmm. Maybe not.

      2. I’m thinking a background image. On the left side is a picture of you dressed like Athena. Light is shining out of your eyes like a lighthouse. You stant above a vast sea of people. Each of the people is in some way representing the various kinds of stupidity. One could have their face made up like a clown, another could carry a religious text, one could have a tinfoil hat, etc. Just for perverse irony, have one crossing the street while looking down and fiddling with their cell phone.

  3. I just popped in to say that this sort of level-headed response to the latest media hysteria is exactly the sort of thing I come to BoingBoing to read. Thanks for posting this. I loved the articles about radiation exposure during the last couple months too.

  4. 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….

    Err… isn’t this pretty obvious given the numbers used?

    300 million use cellphones. Ergo 30 million are in the 10% that use cell phones the most. It doesn’t matter how much they use it, unless the WHO’s dataset is wildly different from the cellphone usage in the US.

    The rest of the math also is confusing to me:

    If everyone’s risk of glioma went up 40% as a result of cell phone use… That’s a one in 40,000 increase in each person’s risk of glioma, which still isn’t very big.

    I don’t know where he went wrong in his math, but something is seriously screwy there. How can he go from saying that everyone’s risk would go up 40% to saying that this implies that everyone’s risk would go up by 0.0025%?

    Maybe he got means that the risk would now be 1 in 40,000, instead of saying that it’s an increase of 1 in 40,000 as he says?

    1. Let’s say you have a 0.00030% chance of an event happening. Then we increase the chances of that happening by 40%- you now have a 0.00042% chance of the same event happening. The actual delta is 0.00012%, which is 40% of 0.00030%.

      1. You’re right. It’s a classic problem when you talk about a percentage increase of a percentage. It’s ambiguous whether it’s a percentage of the original percentage, or an absolute increase. Here he’s using both — it’s both a 40% increase and a 0.0025% increase. I should have read more carefully, it was obvious in retrospect.

  5. Well, that just muddied the water, to me. None of thee figures given can be compared. Let’s try writing some numbers we can compare (feel free to fix my math if I mess up, peoples!)

    (NB: “18,000” looks like a typo: the linked original article has “8,000” value, which I have used below)

    Without cellphones, the average risk of contracting these types of cancer is:
    8,000 deaths/year nationwide.
    307,000,000/8,000 or
    1 death per 38,000 people

    The average risk for the top 10% of cellphone users is 40% greater, or 307,000,000/(8,000 * 1.4), or
    1 death per 27,000 people.

    Including that extra risk, the total risk for deaths from that form of cancer rise to:
    8,400 deaths/year nationwide.

    In comparison, the average risk of avoidable throat cancer from HPV is:
    11,300 deaths/year nationwide, or
    307,000,000/11,300, or
    1 death per 27,000 people.

    Rising in the future to:
    1 per 307,000,000/20,300 or
    1 death per 15,000 people.

    There. See how easy it is to give numbers that can BE COMPARED?

    1. 1 death per 27,000 people

      So with a world population of 7 billion that would be 259,259 additional deaths per year. Trivial really, right? Unless you’re one of the 259,259 who dies. I wonder how many get brain tumors but don’t die. I wonder how much cognitive loss there is. I wonder how high the rate is for children having their brains cooked. That hasn’t be studied yet but they are likely to be even more susceptible.

      I’m a disappointed lately with how determined boingboing is to minimize certain dangers. Like Fukushima Daiichi and now this.

      1. Holy math fail, Batman!

        The figure you’re looking for is the 400 *additional* death in the USA figure. Now, trying to extrapolate that by cell usage in the rest of the world is problematic as I don’t think everyone has the same cell phone usage as found in NA. So, a max of roughly 6600 *additional* death worldwide is what this study would predict.

        Sure, you can always use the ‘oh, but it would be important if it happened to you’ line, but that’s hardly meaningful.

  6. Ah, the changed figure from 18,000 to 8,000 in the linked article is likely because of a later edit:

    *Correction: I previously wrote that 80% of brain cancers are glioma. That’s wrong. Eighty percent of *maliginant* brain cancers are glioma. About a third of all brain cancers are gliomas, per this American Cancer Society press release. Thanks to Geoff Curtis at WeissCom for pointing this out. I’ve made appropriate changes throughout the post. This makes the risk even less scary.

  7. Are these numbers for an average of, say, ten years of cell phone use? Or extrapolated to the 70+ years of cell phone use that most people will now enjoy?

  8. In other words the correlation is overwhelmed by the error in the tiny sample.

    BTW where is the real math? I don’t see the study link, the error analysis, the sample, the statistical calcs – not any math here. Move it along. Nothing to see here.

  9. So there is actually a chance, just moderate your usage? Doesn’t sound too hard of an idea…(oh, and possibly not giving a growing brain(ie little kids) a cell phone, just some thoughts)

  10. You have no idea how insanely happy it makes me that there’s a science and health writer named ‘Herper’. I sincerely hope the politics writer is named ‘Derper’.

  11. The risk is zero.

    That’s why it’s hard to measure statistically.

    We’ve know since Albert Einstein’s Nobel-winning explanation of the photoelectric effect in 1905 that electromagnetic radiation is absorbed in discrete packets called photons. Absorption is all or nothing — either the entire photon is absorbed or none of it is.

    The energy of a photon depends on its frequency alone. Having more photons around doesn’t increase their energies. So the amount of damage that can be done depends on the frequency of the radiation, not the intensity. Higher intensity means more photons, but each one still has the same energy so long as you don’t change the frequency.

    Photons simply don’t have sufficient energy to damage DNA molecules and cause mutagenic changes until you reach frequencies in the near ultraviolet. Cell phones emit microwave photons at frequencies (and energies) a million times smaller. The energy delivered by a microwave photon can make a molecule spin or vibrate a little, but it cannot change the molecule’s structure.

    So it is physically impossible (not unlikely, not low probability — flat out impossible) for cell phone radiation to cause cancer. It simply isn’t sufficiently energetic.

    We went through this same scare once before with power line emissions. Anybody who knew any physics knew where the argument would end up that time and for the same reason — low energy photons do not damage DNA molecules. The same thing will happen here.

    Please, for god’s sake, talk to someone other than epidemiologists. All they measure is correlations. Physics is about causality, a concept on which epidemiology is silent by design. Their statistical methods are unable to distinguish between small and zero. But some things really are zero, and this is one of them.

    1. So it is physically impossible (not unlikely, not low probability — flat out impossible) for cell phone radiation to cause cancer.

      What nonsense. Like your microwave oven, you cell phone causes slight heating in your brain. This causes damage. Repeated damage. And repeated damage to any part of your body increases the likelihood that part will develop cancer. As the cells have to repeatedly regrow they use up their telomeres. They become old and DNA errors are more likely to appear. Thus cancer. And the damage caused to your brain by that heating, well, has to cause some loss.

      But I’m fine with you getting cancer if you are determined to get it. It’s your choice.

      1. Do you know what else causes heating of the brain? Heat.

        The peak power output of a cell phone transmitter is about a watt. Most of that is *not* absorbed by the body, or the phone wouldn’t work. But let’s assume that it is. Increasing the temperature of the room in which you are standing by one kelvin causes more heating than does the presence of a cell phone. If the cell phone does present a cancer risk from heating, it can’t be much larger than the difference between setting your thermostat at 70 versus 72.

        If you think a cell phone significantly heats the brain, then go ahead and do some thermal imaging of brains (human or otherwise) in the presence and absence of cell phone use. If you’re right, the increase should be observable. Has this been done?

        1. So you’re saying that there’s no difference between sticking a hamster in a microwave for a minute, and perching it in front of a 1kw electric heater for the same amount of time?

          The location and penetrative ability is really significant. Skin temperature is a very poor predictor of core temperature. Our mechanisms for detecting and sloughing off extra heat at the skin level are completely different for those for dealing with localised heating in the brain.

          Not that I’m saying there’s a risk here: I’m just saying your comparison of heat sources isn’t meaningful.

    2. The risk is zero.

      I think Maggie’s right that the science is currently on the side of “they most probably won’t hurt you,” but I think it’s silly and arrogant to sit there and use Physics 101 knowledge to “prove” that it’s physically impossible for cell phone radiation to hurt you. If it’s so obvious to any scientist, why are there

      The study, in science talk, says that we cannot discount an association between heavy cell phone use and certain cancers. Not really enough data to assert causation nor probabilities of getting a cancer.

      If you’re genuinely concerned about harm that your cell phone might do to your health, there are very real and large probabilities associated with distracted driving, which can kill you quite quickly and does kill people quite routinely. A far greater cell phone related danger.

      And a larger probability of being killed by a cell phone might be that someone drops one from a high floor of a building and it hits you in your head as you walk by. You have that and being struck by lightning as higher probability events to worry about.

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