Do Cellphones Cause Brain Damage?

Siddhartha Mukherjee, author of the acclaimed The Emperor of All Maladies: A Biography of Cancer, asks do cellphones cause brain cancer? Mukherjee does a good job laying out different research designs–experimental, epidemiological, retrospective and prospective case-control studies–and their potential confounds. The best extant studies find little, no, or even a small beneficial effect, and thus Mukherjee concludes that as of now the evidence remains “far from convincing.”

What he doesn’t do, however, is put the risk of cell phone use and brain cancer in context; that’s a real failing because the fact of the matter is that cell phones do cause brain damage. Cell phones cause brain (and body) damage when people use them while driving. Cell phones distract, whether we measure in the lab or on the road, and they distract enough to make cell phone use not all that different from driving under the influence of alcohol (at the illegal level). In marked contrast to the studies on cell phones and brain cancer the studies on cell phones and driving are broadly consistent and suggestive of a small but significant increase in death (your own and that of others). Here’s a review:

In sum, there is a growing body of evidence, including methodologically sound studies of crash risks, that drivers’ cell phone use substantially increases crash risk. Crash risk increases for men and women, young and old, and for hands-free as well as hand-held phones.

Thus, if you want to avoid brain damage from using a cell phone, wear a seat belt. Or better yet, don’t talk and drive. Of course, that is a message people don’t want to hear which is why we focus on brain cancer and turning cell phones off in airplanes.


This was a stupid post—beneath Marginal Revolution standards.


This was an even stupider comment - beneath Marginal Revolution standards.

If drivers talking on a hands free phone are more likely to get into accidents, then isn't the next question whether drivers talking to passengers in their car are also more likely to get into accidents?

I believe the answer is yes.

If they are teenagers, then yes. Because the stupidity compounds.

Stupid and beneath the usual standard indeed.

From Wkipedia:
Comparisons with passenger conversation:
The scientific literature is mixed on the dangers of talking on a cell phone versus those of talking with a passenger. The common conception is that passengers are able to better regulate conversation based on the perceived level of danger, therefore the risk is negligible. A study by a University of South Carolina psychology researcher featured in the journal, Experimental Psychology, found that planning to speak and speaking put far more demands on the brain’s resources than listening. Measurement of attention levels showed that subjects were four times more distracted while preparing to speak or speaking than when they were listening. The Accident Research Unit at the University of Nottingham found that the number of utterances was usually higher for mobile calls when compared to blindfolded and non-blindfolded passengers across various driving conditions. The number of questions asked averaged slightly higher for mobile phone conversations, although results were not constant across road types and largely influenced by a large number of questions on the urban roads.

A 2004 University of Utah simulation study that compared passenger and cell-phone conversations concluded that the driver performs better when conversing with a passenger because the traffic and driving task become part of the conversation. Drivers holding conversations on cell phones were four times more likely to miss the highway exit than those with passengers, and drivers conversing with passengers showed no statistically significant difference from lone drivers in the simulator.A study led by Andrew Parkes at the Transport Research Laboratory, also with a driving simulator, concluded that hands-free phone conversations impair driving performance more than other common in-vehicle distractions such as passenger conversations.

In contrast, the University of Illinois meta-analysis concluded that passenger conversations were just as costly to driving performance as cell phone ones.[9] AAA ranks passengers as the third most reported cause of distraction-related accidents at 11 percent, compared to 1.5 percent for cellular telephones. A simulation study funded by the American Transportation Research Board concluded that driving events that require urgent responses may be influenced by in-vehicle conversations, and that there is little practical evidence that passengers adjusted their conversations to changes in the traffic. It concluded that drivers' training should address the hazards of both mobile phone and passenger conversations.

RR, You made a selective edit of the Wiki post, which is here

Your post compared talking with cellphone talking, but the other risks of cellphone use and texting are dialing, rubbernecking, reaching, break time distraction etc, etc.

If you compare talking to talking that is one thing, but the cellphone use involves more than talking.

There is increasing evidence that there is some risk of cancer, even from just carrying a cellphone that is turned on so that people can reach you.

The people who block traffic in the sidewalks, drive badly, or create noise pollution in public places because carrying on their phone conversations are more important to them are so annoying that it is a guilty pleasure to think of them coming down with cancer. But the schmucks who have to carry around their phones, turned on, so people can reach them but who otherwise don't use them are also at risk, which seems unjust.

Great post, and an example of what (I heard) Henry Hazlitt said about the seen and unseen (borrowed from Bastiat?).

Getting into a car also increases your chance of an auto accident, but we still do it. Don't forget about the benefits side!

While I can understand irritation at Alex Tabarrok's lead-in to his point about driving and cell phones (although, personally, I thought it was amusing), I nevertheless think he is making a good point: it does seem to me that cell phone usage -- even hands free cell phone usage -- impairs driving ability. Of course, in the end, it's important to have scientific studies to back up this claim; and, if I remember correctly, there is one (although I don't have the citation handy, and more similar studies also are needed).

Regarding the difference between a driver's hands-free cell phone usage and having a conversation with passengers in a car, I think there may be scientific evidence to back up a difference. And, in common sense terms, I think this difference can be explained by the facts that a) there is less concentration needed to communicate in person and b) there is less psychological "pressure" on a driver to keep a conversation "going" and ignore his/her responsiblities as a driver when he/she is talking to passengers in a car than when he/she is talking to someone over a cell phone.

When a driver is talking to other people in a car, he/she knows has an easier time communicating to others (they can read his body language, etc.), and he/she also knows that everyone else is aware of the driving conditions. However, when a driver is talkling to someone on a cell phone, he/she needs to expend more "concentration" to make his/her points and decipher what the other person is saying, etc., and he/she also has to expend more "concentration" to keep the conversation "going" with someone who isn't aware of what's happening around the driver.

Benjamin Hemric
Sun., April 17, 2011, 9:28 a.m.

I like the post myself.

I like the post as well. I'm not sure why people think it is stupid.


Yes. I don't see the problem at all.

It's a stupid article because Tabarrok neglects to mention how much speeding is a factor in the frequency and severity of car accidents.

You might ask why he has to mention that in an article about Cell Phones and Driving. The answer is it's the exact same reason Mukherjee should have taken the time in his work on Cell Phones and Cancer to talk about Cell Phones and Driving.

To elaborate on my other comment, it's acceptable to use a study on Cell Phones and Brain Cancer as a spring board to look at the other way a cell phone might damage your brain. But criticizing someone doing valuable research for not making this leap for you, one which would jump from a field of his expertise to one that is not, is just a terrible way of getting from subject A to B.

P.S. -- I'd like to note that when I started writing my comment above (which I finally posted at 9:28 a.m.), there were only the first three comments in this thread. RR had not yet posted his very informative comment on a number of scientific studies on this question. Hats off to RR!

Benjamin Hemric
Sun., April 17,2011, 9:41 a.m.

Ben, Before you praise RR for his comment, you should read the Wiki post he selectively edited which is listed now in my reply to him above.

Bill, good point! I will have to eventually check out the whole Wikipedia article (and also judge for myself whether the studies seem valid or not). Thanks for alerting me.

But aside from praising RR for actually citing some studies, the purpose of my second post was to point out that my first comment was not ignoring RR's posted comment (as it seems to be doing), but was in fact written before I saw his comment.

Also to be fair to RR, the topic under discussion, at least so far in the thread, seemed to be specifically a comparison between talking with passengers and (hands free) cell phone talking. (Although, I'm still skeptical, until I read them more carefully, about the validity of the "no difference" studies cited.)

But, nevertheless, I think your points are good ones too. And I eventually hoped to read the other parts of the Wiki article, and also to look more closely at the ones comparing plain talking to hands free cell phone talking.

Benjamin Hemric
Sun., April 17, 2011, 10:55 a.m.

Second Yomtov. Keep it up with this type of comment.
Is the criticism that people don't want to hear, or that they disagree?
Do they have evidence for their position.

They don't view a blog post the way I see a blog post.

The surprising evidence is that there is limited, at best, evidence of cell phone use causing accidents. The best study on cell phone use and driving is by two economists finding no evidence linking the two. Bhargava and Panthania ( look before and after nighttime minutes start - huge first stage power in cell phone usage, zero reduced form relation to accidents. Jeff Ely wrote some nice summary work about how most cell phone-accident studies are flawed, typically failing to take into account baseline cell phone usage rates.

I don't buy that THE REASON we focus on brain cancer and cell phones on airplanes is because we don't want to talk/think about cell phone usage while driving.

It's probably true that most don't want to hear about how bad cell phone usage while driving is, but it doesn't seem likely that's the one causative factor of the other things.

@Ed: You say there is increasing evidence of a risk of cancer without any proof. That's your right, I suppose, but it seems pretty dumb in light of the NYT article linked in Alex's post.

It's plainly false to say that we don't focus on the risks of using a cell phone while driving. The past decade has seen hundreds of jurisdictions pass laws banning the practice or requiring hands free setups. I'm not aware of one that has passed a law banning holding a cell phone against your head.

There are some that have banned using cell phones while pumping gasoline, which is just as stupid as banning holding cell phones against your head.

". . . don’t talk and drive." I think you meant "don't talk *on a cell phone* while driving," but even carrying on a conversation with a passenger is probably somewhat distracting (though less so than talking on a cell phone). The same is true for listening intently to the car radio or CD player.

On the other hand, in many contexts the additional risk from driving while also engaging in one of these activities is small, and is outweighed by the benefits these activities provide. It may, after all, be reasonable to do something else while driving.

I, for one, would be quite happy with a car that left me completely unable to hear what any of my passengers were saying, even if there was no associated safety benefit.

Well, that depends on who the passengers are.

You never hear talk about a link between residential cordless phones and cancer, and they radiate at higher energies than cell phones. That to me is a pretty good indicator of what motivates the "science."

"they distract enough to make cell phone use not all that different from driving under the influence of alcohol (at the illegal level)"

Red flags: (1) they didn't use a control. They didn't have a comparison to a non-impaired condition. That leads me to believe that (2) it may be a non-result because they 'show' no statistical difference for the threshold of blood-alcohol level which is probably not really that impairing.

What is the effect size compared to the benefit of being able to talk on a cell phone? Again, a "no statistical difference" is not very satisfying. Driving is inherently dangerous, what are the standards for making more rules around a marginal increase in danger of something inherently dangerous? Is the standard for legal action a vocal outcry from advocate groups and easy statistics (compared to the difficulty of accounting for the benefits of cell phones) armed with conventional wisdom(often wrong)? When my child had a seizure in the car we were able to use the cell phone to find a nearby hospital. Sure, an extreme anecdote and no cop would give us a hard time in that situation (haha), but it's just a point on the utility continuum. Informing people of the risks and then modulating torts and insurance rates based on behavior may be good enough to internalize the costs. Alex is correct that we should wait until all effects can be accounted for. It's the same thing with the cancer. Almost everything causes cancer, being alive and human being the biggest factor. In some cases the precautionary principle is warranted, but on the other hand, deez nuts seem are a big cancer threat but I choose to tolerate them, for utility considerations I won't go into.
* Average individual appears
* Subtle effects that can be
detected with special tests

Oops. This range is more relevant.
0.06–0.09 Impairments: * Blunted feelings, * Disinhibition, * Extroversion, * Reasoning, * Depth perception, * Peripheral vision, * Glare recovery

Since the issue is cancer and brain damage from holding the cellphone next to your cranium, what if there is a risk. Is the risk eliminated if I use a tethered earbud? An earbud with bluetooth?

If either of the above alternatives eliminates an uncertain risk, would mandating that cellphones come with these options be a proper response? Would mandating usage?

Or, would not mandating that phones not come with these features be preferred, leaving those who wish to protect themselves from the risk buy their own earpiece? Given the litigious society we live in, would manufacturers choose to offer these earbuds or bluetooth earbuds as a part of these products so they could say that the consumer chose not to own them?

Finally, manufacturers sometimes offer products that carry health risks, and are aware of them. They are reluctant to advertise that the risks are low, for fear that they will be sued for misrepresentation, but on the otherhand, are members of trade associations that make the same statements. (Think Tobacco trade association). What should be the scope of liability if the industry sponsors an organization that attacks critical studies, promotes weak ones or promotes uncertainty, when the individual members would be reluctant to do so themselves because of potential liability. Should liability be lower if acts are pursued collectively than if they are pusued individually.

Or, you can think of this a different way: what role should a trade association play if there is an negative externality to the product?

I personally agree with you . I think cell phone usage (even hands-free ) is a great risk while driving. I was surprised by the Wikipedia article that seemed to indicate the scientific eveidence is mixed ; I would have thought there is incontrovertible evidence that cell phone usage is dangerous. I just posted it as a response to Juan's query.

I'm on the other sude of the debate-- I am very skeptical that just talking would be a danger, though I agree that dialing (or hunting through a contact list) and certainly texting are dangerous since they require one's attention to be taken off the road, and also one's hands to be engaged in something other than driving.

Perhaps the risk is due to having to keep an eye out for the police when you are talking on the phone, hence reducing your attention on actual safety hazards?

Even assuming that cellphones cause brain cancer, it would have to be a very small increase in risk or otherwise we would have convincing epidemiological evidence already after so many decades of use. My question then would be, why should be hold the cellphone industry to higher standards than the food industry. Brain cancers are quite rare and even assuming a 100% increase in risk, in absolute terms, it's not a large negative externality on society, especially when compared to the positive externality that instant communication has on society.

On the other hand, hypertension, obesity and heart disease contribute a huge burden to society in lost productivity and health costs but we don't mandate pretzel vendors to advertise "eating X number of pretzels over Y months will increase your lifetime risk of hypertension by Z%".

Darren, Good points.
I don't think an industry should be liable for individuals assuming known risks, nor was that my point.

I know the risks of obesity, but do I know the risks of cellphones and brain cancer? Is there a warning?

Does the industry know more than I do, have withheld information, or sponsored disinformation? So, if they know there is a risk but do not disclose, that is one thing; if they know a risk and disclose, that is another.

I would not hold them liable if they disclose the known risk. But, what would you say if they knew the risk, did not disclose or warn, and had their trade association hire a PR firm to muddle the safety message, and your 10 year old now wants his own cellphone? What if the risk is known, is small, and the trade association claims the science doesn't support adverse claims, when most studies do.

That's where things get interesting.

Now, with respect to that 10 year old...

last line of third paragraph should read: "that the consumer chose not to use them?"

You forgot to mention the risk of talking on a cell phone at a stoplight which turns green and getting shot in the back of the head.

But then someone next to you can use the cellphone to call 911. Cell phones repairs brain damage!

Eventually the class actions will be filed- evidence or not. One reason I have always been hesitant to invest in the industry, even if some of them have attractive dividend payouts.

Also, for those criticizing Alex's post- I think you are not quite understanding why he made it. The key word in the post was "context".

They don't get it. Alex is being mildly humorous. Tyler's humor is like "the commenters are advocating for Dunning-Kruger" and I picture him cackling maniacally at his keyboard.

Are we that stupid that we don't realize that there are other ways in which cell phone usage can be negative? It would be ridiculous for a cancer/cell phone usage study to go into some totally irrelevant subject matter. In fact, it would call the author of the study's objectivity into question. A reader would have to wonder whether the writers simply had it in for cellphones.

Also, its absurd to suggest that we are investigating the cancer/cell phone link only to throw people off the car crash/cell phone trail.
I vote for substandard post.

Re: Cell phones cause brain (and body) damage when people use them while driving.

This is incorrect. It is more accurate to say "if drivers are distratcted using a cell phone with a serious accident resulting." This is a tiny fraction of all occasions when cell phones ae in use.

For an economist, Alex doesn't appreciate additive probabilities from independent events.

So, when his kid is (1) talking on the cellphone and (2) at the same time with another kid in the car (3) after having had a few drinks, and his kid sees at the last minute a pedestrian in the crosswalk, reading Marginal Revolution on an Ipad, Alex will have one less future reader and one more headache but not from cancer.

•20 percent of injury crashes in 2009 involved reports of distracted driving. (NHTSA).
•Of those killed in distracted-driving-related crashed, 995 involved reports of a cell phone as a distraction (18% of fatalities in distraction-related crashes). (NHTSA)
•In 2009, 5,474 people were killed in U.S. roadways and an estimated additional 448,000 were injured in motor vehicle crashes that were reported to have involved distracted driving. (FARS and GES)
•The age group with the greatest proportion of distracted drivers was the under-20 age group – 16 percent of all drivers younger than 20 involved in fatal crashes were reported to have been distracted while driving. (NHTSA)
•Drivers who use hand-held devices are four times as likely to get into crashes serious enough to injure themselves. (Source: Insurance Institute for Highway Safety)
•Using a cell phone use while driving, whether it’s hand-held or hands-free, delays a driver's reactions as much as having a blood alcohol concentration at the legal limit of .08 percent. (Source: University of Utah)

Headline: Cellphones do brain damage to economists when they seek to compare them to other obvious risks of cellphones, survey of Marginal Revolution Post and comments reports. Post commenter is urged to fasten his seat belt and not talk to passengers as his comment distracts others from obvious risks which he seeks to trivialize by comparison.

From the National Cancer Institute summarizing cellphone brain cancer studies:

"What studies have been done, and what do they show?
Numerous studies have investigated the relationship between cell phone use and the risk of developing malignant and benign brain tumors.

The most significant study of long-term use is the 13-country Interphone study, which is a multinational consortium of case-control studies. Interphone was coordinated by the International Agency for Research on Cancer (IARC) (3). The primary objective of the Interphone study was to assess whether RF energy exposure from cell phones is associated with an increased risk of malignant or benign brain tumors and other head and neck tumors. Participating countries included Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and the United Kingdom (4).

Interphone researchers reported that, overall, cell phone users have no increased risk for two of the most common types of brain tumor―glioma and meningioma. In addition, they found no evidence of increasing risk with progressively increasing number of calls, longer call time, or years since beginning cell phone use. For the small proportion of study participants who reported spending the most total time on cell phone calls, there was some increased risk of glioma, but the researchers considered this finding inconclusive. The study was published online May 17, 2010, in the International Journal of Epidemiology (5).

Additional studies have investigated the risk of developing glioma, meningioma, and acoustic neuroma. Results from the majority of these studies have found no association between hand-held cell phone use and the risk of brain cancer (6–11); however, some, but not all, studies have suggested slightly increased risks for certain types of brain tumors (12, 13).

Two reports published in November 2004 by researchers from individual countries that participated in the Interphone study described the results of assessments of cell phone use and the risk of acoustic neuroma. One report described a Danish case-control study that showed no increased risk of acoustic neuroma in long-term (10 years or more) cell phone users compared with short-term users, and there was no increase in the incidence of tumors on the side of the head where the phone was usually held (14). The other report described a Swedish study that examined similar populations and found a slightly elevated risk of acoustic neuroma in long-term cell phone users but not in short-term users (15).

A pooled analysis of data from Denmark, Finland, Norway, Sweden, and the United Kingdom did not find relationships between the risk of acoustic neuroma and the duration of cell phone use, cumulative hours of use, or number of calls; however, the risk of a tumor on the same side of the head as the reported phone use was higher among persons who had used a cell phone for 10 years or more. Some other studies have reported similar findings (16). However, there is concern that people with a tumor on one side of their head might be more likely to report phone use on that side (12).

Other reports from the Danish and Swedish researchers who collaborated in the Interphone study investigated whether a relationship exists between cell phone use and the risk of meningioma or glioma. These studies compared individuals with meningioma or glioma with a control group of disease-free individuals and found no link between these conditions and cell phone use (17, 18).

In addition, pooled analyses of data from four Nordic countries and the United Kingdom did not show overall associations between the risk of glioma or meningioma and the cumulative hours of cell phone use or the number of calls (19, 20). There was a slightly increased risk of glioma occurring on the same side of the head as the reported phone use among persons who used a cell phone for at least 10 years (19).

In an attempt to avoid the issue of biases associated with case-control studies, researchers defined a cohort of 420,095 persons in Denmark with cell phone subscriptions and linked this roster with the Danish Cancer Registry to identify brain tumors occurring in this population (10, 11). Cell phone use was not associated with glioma, meningioma, or acoustic neuroma, even among persons who had been subscribers for 10 or more years. Cell phone service subscription does not necessarily relate directly to cell phone use, duration, and frequency of use. A listed subscriber may not be the primary user of the phone. However, this type of prospective study has the advantage of not having to rely on people’s ability to remember past cell phone use.

Incidence data from the Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute (NCI), which is part of the National Institutes of Health (NIH), show no increase in the age-adjusted incidence of brain and other nervous system cancers between 1987 and 2007, despite the dramatic increase in the use of cell phones (21). NCI continues to monitor cancer incidence data to detect any change in the rates of new cases of brain cancer. If cell phones play a role in the risk of brain cancer, one would expect to see an increase in rates because average monthly hours of cell phone use have increased regularly for the past decade in the United States.

There are very few studies of the possible relationship between cell phone use and tumors other than those of the brain and central nervous system (22–25)."

If I see a newspaper or magazine article with the title "Does BLAH BLAH BLAH cause SOMETHING HORRIBLE?", I feel I can safely assume the answer is No and save some time by not reading the article.

It's basic logic: if the answer was Yes, the headline wouldn't be a freaking question. It would read, "BLAH BLAH BLAH causes SOMETHING HORRIBLE."

A good rule of thumb, I agree.

However 95% of the time, the headline that claims “BLAH BLAH BLAH causes SOMETHING HORRIBLE.” is false too. So a better rule of thumb is to ignore newspapers all together as a source of medical advice.

I wonder how much sound quality has to do with it. Despite significant advances, a mobile phone has MUCH lower sound quality than actually sitting next to someone. How much processor time does the brain devote to deciphering the noisy, static filled, low volume sounds that we can interpret as speech?

I don't think AM radio killed that many people.

Lots of people driving and using the phone try to pretend they aren't driving, which ironically leads them to have to spend too much attention to the conversation.

How to judge the quality of a Marginal Revolution post: if the post critcises something I do regularly, the post must be stupid and wrong.

I don't know about y'all, but I hear a lot more about the dangers of cell phones and driving than about cell phomes and brain cancer.

But maybe I just pay more attention to the cell phone driving dangers as I have been nearly run over by a woman in a minivan who ran through the stop signing I was holing while working on a road crew.

As for cell phones and planes, I've had pilots tell me they can sometimes here interference in their headsets and that there is some small possibility of interference with instrumentation. It's not necessarily a big risk, but it's a highly regulated environment where even small risks can be mitigated.

Dear all,
I hope you are knowing how many years it took and how hard it was to prove cigarette smoking can cause cancer. The corporates are involved in research and funding it.
These kind of studies are statistical. It requires proper analysis to make a meaningful conclusion.
So, these are not like physics where one can predict something. Such coclusions are very difficult to draw as the process is going on openly in the "world - system" invloving too many parameters and that too for a long time.

i suggest alex makes public his email so haters write to him. the rest of the people can still have a nice discussion here.

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