Apr 30 2012

Another Cell Phone – Cancer Review

There is an ongoing scientific discussion about the safety of long term cell phone use. The primary question  is whether or not long term exposure to non-ionizing radiation can increase the risk of brain cancer. There are further questions about whether or not such radiation can cause any health problems or symptoms.

As with any complex area of scientific research, perhaps the best way to evaluate the question is to put together a panel of experts to review all the existing evidence and then come up with a consensus opinion about that evidence. This is no guarantee of being right – the primary issue that tends to come up with such expert panels is that they were systematically biased toward one side of the debate. But assuming no major asymmetry in the constitution of an expert panel, they are an excellent way to evaluate the current state of the evidence on a specific question. Even better, of course, is when multiple independent panels all agree.

Recently an expert panel for the UK’s Health Protection Agency (HPA) reviewed the evidence for cell phone safety concluded that there is no clear evidence for any harm. This is good news. Their findings are similar to other reviews of the evidence, although often there is a difference in emphasis. For example, last year the International Agency for Research on Cancer (IARC) reviewed the same evidence and concluded that:

 “the evidence, while still accumulating, is strong enough to support a conclusion and the 2B classification. The conclusion means that there could be some risk, and therefore we need to keep a close watch for a link between cell phones and cancer risk.”

They are not really saying anything different from the HPA – both groups concluded that there is no clear evidence of risk, but that further monitoring is prudent. The HPA, however, chose to emphasize that there is no conclusive evidence of risk, while the IARC chose to emphasize that there is no conclusive evidence that there is no risk. There  classification means that there may or may not be a risk, but further research is warranted. Meanwhile the FDA has concluded that: “the weight of scientific evidence has not linked cell phones with any health problems.” The Federal Communications Commission has this to say:

“There is no scientific evidence that proves that wireless phone usage can lead to cancer or a variety of other problems, including headaches, dizziness or memory loss. However, organizations in the United States and overseas are sponsoring research and investigating claims of possible health effects related to the use of wireless telephones.”

These all sound like variations of the same conclusion – there is no clear evidence of harm or risk, but we should continue to do research and monitor the results. Overall there is more caution when children are concerned, because there are fewer studies, children’s heads are smaller, and if cell phone use is started at a young age then lifetime use will be greater. Still there is no evidence of harm, but there are a priori reasons for greater caution.

Getting back to the new review by the HPA, here are their key conclusions:

  • The evidence suggests that RF field exposure below guideline levels does not cause symptoms in humans and that the presence of RF fields cannot be detected by people, including those who report being sensitive to RF fields.
  • A large number of studies have now been published on cancer risks in relation to mobile phone use. Overall, the results of studies have not demonstrated that the use of mobile phones causes brain tumours or any other type of cancer.
  • As mobile phone technology has only been in widespread public use relatively recently, there is little information on risks beyond 15 years from first exposure. It is therefore important to continue to monitor the evidence, including that from national brain tumour trends. These have so far given no indication of any risk.
  • Studies of other RF field exposures, such as those at work and from RF transmitters, have been more limited but have not given evidence that cancer is caused by these exposures.
  • Research on other potential long-term effects of RF field exposures has been very limited, but the results provide no substantial evidence of adverse health effects; in particular for cardiovascular morbidity and reproductive function.

There are several types of evidence that address this question. The first is the basic science plausibility of health effects from non-ionizing radiation. By definition, non-ionizing radiation (like radio-frequency radiation used by cell phones) is not energetic enough to break chemical bonds. It therefore should not cause DNA mutations, which is believed to be the primary mechanism by which high energy radiation causes mutations that lead to cancer. Some scientists have concluded from this that cell phones cannot possibly cause health effects, and while this conclusion may be true it is a bit premature. More subtle biological effects are not likely but are also not completely implausible. There is some local tissue warming, for example. The magnitude of this effect is very small, but it is not zero. My own feelings on the question is that biological effects from cell phone radiation is very unlikely, but it would be premature to declare them impossible. Therefore clinical research into the effects of chronic cell phone use are warranted.

There are two basic types of clinical evidence – observational and experimental. We do not have any experimental data on cell phones and humans because such studies are both unethical and impractical. You cannot randomize study subjects to either be exposed to or not be exposed to a potential environmental risk factor. You can’t force people to use cell phones (or smoke, or eat a possible toxin, etc.) to see if they cause harm. So we have to get by with observational data.

There have been a number of observational studies of cell phones and brain cancer. They generally take two forms: either looking at people with and without brain cancer and then finding out their cell phone use history, or dividing people into groups based on their cell phone use and then following them for their subsequent rate of brain cancer. We can also look at overall brain cancer incidence to see if it correlates with overall cell phone use.

These are the studies that the above expert panels and agencies have been reviewing, and which do not show a clear correlation between cell phone use and brain cancer. One limitation of such studies is that they cannot be extrapolated beyond the duration of observation. We now have about 15 years of observational data for cell phone use, so our conclusions about safety from this data are limited to about 15 years. We cannot know that cell phone use is safe when used for 20 or 30 years until after we have observed effects for that long.

Another way to look at this type of data is this – if we take the hypothetical situation that there is zero health risk from cell phone use, what would our observational data look like? We would never be able to prove that the risk is zero. Rather, the more data we gather then the smaller the possible remaining risk (risk that is too small to be detected by the current data). This uncertainty will approach, but never quite reach, zero. So we can never prove a zero risk, but we can increase our confidence that the risk is too small to worry about. Also, the longer we gather data and make observations then the longer the period of exposure over which we can say there is likely no risk.

Of course if there is a small risk from cell phones the data will look exactly the same, until we gather enough data to detect with statistical confidence this small risk.

Agencies and panels who have reviewed the data all agree that we have not detected a statistically significant risk from cell phone use out to the current limits of the data – 15 years. They also all agree that we should continue to conduct research and monitor cancer rates. Where there is some difference is in the application of the precautionary principle. Given this current state of the data, how cautious should we be about the potential health risks of cell phones. There is no objective scientific answer to this question. This comes down to philosophy and personal choice. How valuable, for example, are cell phones? Many people find their convenience worth even a known small risk, let alone a possible but unproven small risk. We also have to consider how many lives are saved by the availability of cell phones in emergency situations.

Cars are an obvious analogy to cell phones. In the US there are about 40,000 motor vehicle related deaths per year. This is far more than the possible remaining risk from cell phone use, given current evidence. Yet, we accept this risk because of the convenience that motor vehicles provide, in addition to being a critical part of the infrastructure of our modern society.

It is interesting to think about what risk you would accept from cell phone use. Let’s say that eventually we find there is a small increased risk of cancer from cell phones. At what point would you conclude that this risk is high enough to stop using cell phones? I think there is sufficient evidence to conclude that we are already below that number for me personally. Even if there is a small risk, it is too small to worry about. But I also welcome reassurance from further research.

24 responses so far

24 thoughts on “Another Cell Phone – Cancer Review”

  1. cgervasi says:

    I read a book about this. It inspired me to write an article about it. I would love to hear the Rogues comment on the logical fallacy behind the reasoning of people concerned about non-ionizing radiation. It seems to me they don’t start with a clear claim, so anything unexpected about RF they take as supporting their case. What do you call that fallacy? It’s like the fallacy of not having a clear claim to begin with. I found this very frustrated. It’s very hard to refute an unclear argument like “there’s something scary going on with regards to wireless technology and the human body.” I’d love hear Steve and the gang take them on on the Skeptics’ Guide.

    Here’s what I wrote on the topic: http://bit.ly/oWCMze

  2. addisontree says:

    Excellent post.

    I’m confused about the following claim though:

    “We do not have any experimental data on cell phones and humans because such studies are both unethical and impractical. “

    An experimental study shouldn’t be considered unethical unless we have some idea of a plausible mechanism of harm. Currently we don’t have a plausible mechanism for harm only the plausibility of an unknown mechanism at work. Further, as you point out in your post, the existence of such a mechanism seems unlikely. Aren’t experimental studies performed all the time under these conditions? For example, FDA trials on new drugs? Perhaps a better example would be the experimental acupuncture studies. Before they were conducted there was a small chance that acupuncture might have some biological effect through an unknown mechanism. (Obviously the mechanism would not be “qi” but it was conceivable that stimulating the skin with needles might have some physiological effect.) Since anywhere there is a biological effect there is a potential for harm this would imply that there was an unknown (though tiny) amount of risk associated with a blinded acupuncture experimental study. No one thinks that such an experiment is unethical; why do we think it would be unethical for cell phones?

    As to impracticality, I can think of a fairly practical way to perform the experiment. Study members where headbands when they sleep. Some headbands emit RF similar to cell phone communications; other headbands emit a small amount of heat; other headbands are completely inert. The function of each headband is blinded from the user and the experimenter. After a year of 8 hour a night exposure we look for any health effects over that year and the succeeding year (or two).

    Wireless RF communication is hugely important to our society’s economy, social health and education. Not being able to quantify RF risk definitively allows charlatans and fringe pseudo science “mavericks” to prey on this uncertainty. The gain from a double blinded experimental study seems more than adequate to justify any minuscule risks such an experiment might entail.

  3. DS1000 says:

    @ addisontree

    I agree with your logic, although I think there is a psychological difference between “try this drug/experiment/etc. , we think it will help you” and “try this, we want to know if it hurts you.” (Even though in this case there’s no scientific reason to suspect that cell phones would harm.)

  4. addisontree – I have to disagree. You don’t need to know the mechanism. If there is any possibility of harm the study is unethical. (This is different, btw, when you are studying a treatment that has possible benefit, then you have risk vs benefit. But if all you are looking for is possible harm you have a problem.)

    If you say there is no possibility of harm, then there is no point to the study, and that is unethical. Bottom line – you can’t expose a study subject to possible harm just to see if they are harmed.

  5. addisontree says:


    “If there is any possibility of harm the study is unethical?”

    Isn’t there always the possibility of harm? Anytime we study a new biologically active treatment we run the risk of discovering a mechanism of harm that was unknown before the study. Seems like the real condition for the ethics of performing an experimental study is “Is the possibility of harm small enough that a reasonable and well informed person would be willing to take the risk?”

    If the experiment teaches us something then there is value in it. We have to decide when the value outweighs the risk.

    Apologies if I’m being naive here. I’ve never studied medical ethics; I’m genuinely confused about this point. If anyone can point me to a good primer on the subject I would be willing to do the reading.

  6. ccbowers says:

    “If there is any possibility of harm the study is unethical. (This is different, btw, when you are studying a treatment that has possible benefit, then you have risk vs benefit. But if all you are looking for is possible harm you have a problem.) ”

    I have to disagree (just) slightly here in your comparisons to smoking or toxins. Those are known to cause harm, and presumably have no meaningful benefits to the participants in such a trial. I agree that there is an ethical consideration to the cell phone use experiment, but it is different (not only quantitatively but qualitatively).

    Cell phones are not known to cause harm, so at the very worst we are agnostic towards their risks, but a more balanced perspective is that they likely don’t cause harm. We do phase I trials in humans for potential medications which by definition are not designed to help the participants (by definition), yet pose some risk (again by definition). I think the impracticality is the more obvious obstacle here.

  7. ccbowers says:

    In reading addisontree’s post, I do see an ethical problem with that experiment. The problem in that case is that you are not merely replicating the behavior of what people already do, you are increasing the exposure to levels well beyond normal cell phone use. Since there remains the possibility that cell phones currently have a very small risk of harm (medium or large risk have all but been ruled out), amplifying this effect is problematic. Also, at the end of 1-2 years we will either no nothing new or we will have caused harm to people while not learning much about normal cell phone use

  8. robm says:


    Experimenting on people without a possibility of a benefit because at best the experiment does no harm. Even the flimsiest alt med studies are designed to help. The experiment would be designed to harm people and compare them to a control group. How could you justify this study designed to cause harm is ethical, while saying another involving deliberate injury, infection, or exposure to harmful conditions is not? You can’t know in advance what the results will be, thats the point of the study. Given that how do you justify a only potential harm to the people being studied?

  9. addisontree says:


    There are probably other problems with the example experiment I described. The example does (I think) provide a counter example to the claim that all such experiments would be impractical. Any impracticality can be overcome with a little ingenuity so it’s really the ethics that prevent us from doing these experiments.


    But participants would reap a benefit. Not all benefits are health related. Many people would get a real sense of meaningful satisfaction to being able to assist in showing that cell phones are safe (or to assist in any scientific endeavor that helps us learn more about the world). Don’t we do studies where the overall health is not improved (even in best case) but the quality of life is?

    Still, you make a good point. I’ll think about this some more.


    Ethical theory aside, there is an underlying communications issue here.

    When the “average person” hears the claim “It is unethical to perform cell phone experiments” then what they’ll take that to mean is that “Cell phones are more dangerous than all OTC drugs and many prescription drugs” because it wasn’t considered unethical to do double blinded experiments with these. For these people it won’t matter how often we say that cell phones are almost certainly safe if we also say that experimenting with low power RF on humans is unethical.

    Personally I get that there can be a distinction (though I’m obviously uncertain as to what that distinction is) but I don’t think most people will. I’m reminded of the “take thimerosal out of the vaccines” decision by the CDC years back. Ethically it may have been the right thing to do but the negative consequences were significant.

    (Sorry for all the posts. I’ll be quiet for awhile now.)

  10. jre says:

    Addisontree, you ask some excellent questions about a fascinating subject. A good place to start finding answers is in the Belmont Report, which is the foundation for research ethics protections in the US. Internationally, the cornerstone document is the Declaration of Helsinki.
    Belmont and Helsinki both require that any research involving humans be conducted so as to respect their rights (especially the right to make informed decisions), confer maximal benefit to study participants while subjecting them to minimal risk, and apportion the benefits and risks of research justly.
    As a practical matter, this means that a researcher cannot, by law, conduct human research without the approval of an Institutional Review Board (IRB) in the US, or its equivalent in other countries.
    I think I am on solid ground in predicting that, when you submit to the IRB your research protocol requiring that subjects wear RF and dummy headbands so that investigators can compare the rates of cancer in the two groups, your submission will be, um … not approved. Don’t take it personally.

  11. Fred Cunningham says:

    As I recall there was an experiment in which mice with a condition that resembled Alzheimer’s were exposed to high levels of radio frequency radiation and an improvement was noted. I don’t know if this will lead anywhere but something like this could be a possible benefit that could change the ethical constraints of running the experiment. The levels were much higher than normal cell phone exposure.

  12. ccbowers says:

    “Any impracticality can be overcome with a little ingenuity so it’s really the ethics that prevent us from doing these experiments.”

    Well you designed an unethical trial, but I think you can make an ethical experimental trial, but just not one that is practical or feasible. Its odd that your most recent comments appear to directly contradict your original comment (you initially stated that you thought there shouldn’t be an ethical problem, now you say that ethics is the only obstacle). Ethics and feasibility can be both obstacles, but since unethical trials are nonstarters, I think the feasibility is the main issue.

  13. etatro says:

    Addisontree: Basically Steve seems to be applying ethical considerations to the standard of medical research, and research involving human subjects that we apply in the US. We have extraordinary standards that seem to go beyond sometimes what “ethical theory” would imply.

    In designing a study, we have to spell out all the potential harm that could come to a study-participant due to the procedure. Next, we have to spell out all the potential benefits to the study participant due to the procedure.

    For example: I am interested in what happens during early, acute influenza to the gut associated lymphoid tissue. So we will give the study participant all the standard care & treatments for the flu. But to answer my observational question, we will do a colonoscopy. This involves a small amount of risk – it’s uncomfortable, there’s a extremely low chance for infection, the participant might miss a day at work, and the participant will be sedated, and there’s a low risk that she’ll respond negatively to the sedation. The risks are minimal, though; colonoscopies are recommended for people over 50, and the procedure is performed by an expert in a pristine environment. The potential benefits to others: say — my research results could lead to a cure for all influenza for all time. The benefit to the participant herself are also minimal, knowledge of colon-health could be beneficial is anything aberrant but unrelated to the flu are found. As far as the flu itself goes, there’s no benefit, she would get the same care she’d otherwise receive.

    A more complicated example is an experimental drug to treat the flu. Here, the risks are larger, the drug could have side effects. The benefits are better, it could cure her flu. Based on pharmacology, experiments with cells in the lab, experiments with animals, we should have an estimate of the risks and potential benefits. We have to explain all of this to a review board AND to the study participant.

    In the case of doing an experiment where we give something we suspect to be harmful, there’s no potential benefit to the subject and a low risk. With a risk/benefit, there’s no benefit, but low/unknown risk. We can’t do the study. A hypothetical example would be to test whether a chemical I synthesized in the lab is toxic. I don’t know. I know there are no benefits to injecting it. But I want to know if it’s toxic. I can’t ethically do a randomized placebo controlled study to inject people with a compound that has no benefits and unknown toxicity.

  14. Mlema says:

    you may be unfamiliar with the typical colonoscopy prep.
    Most likely contraindicated for an influenza patient.
    (perhaps your example was entirely fictional – hope so 🙂

  15. Jared Olsen says:

    Even if we gave up our mobile phones wouldn’t we still be bathed in RF radiation from other sources?

  16. addisontree says:


    Sorry about the confusion. My writing is sometimes not very clear.

    I don’t think there is any ethical issue with doing a human experiments on the effects on low power RF. I’m told by the experts that any experiment in which the participants can experience only harm (even in tiny amounts) is unethical and I’m willing to accept this since I have reason to believe they know much much more about the subject than I do. (Although I won’t really feel comfortable until I better understand the rationale behind their assertion, hence my desire to learn more.)

    I’m assuming there are two independent qualities for any give experiment: (1) Is the experiment ethical? (2) Is the experiment practical? A practical (or feasible) experiment would not be unduly expensive nor would it go beyond the limits of our current technologies.

    Although the original “headband” example experiment may be deemed unethical I think it still serves as an example that low power RF experiments can be practical/feasible. The headbands in question might cost $10-$20 each and I bet one could find electronics manufacturers willing to donate the equipment. (After all it’s in their interest to support research like this even when the research is conducted independently.) The burden on the participants is minimal. Participant compliance can be explicitly monitored instead of having to rely on self-reporting. (For example, the headbands might measure temperature on the inside surface and record the result every thirty minutes. If temperature falls much below 98.6F then we know the participant took off their headband during the night.)

    Why would we think such experiments would be impractical? It’s not like we need to set up a cell phone contract for each participant. We only need to simulate the RF transmissions associated with a cell phone. The participants would not even need to have “bars on their phone” where they sleep.

    Am I missing something?

  17. addisontree says:

    @jre and @etatro

    The Belmont Report was a good read and helps a lot. The report itself seems to allow for research with minimal risk and no benefit to the subject (assuming participants are (1) well informed and comprehend both the risks and the lack of benefits and (2) conforms to the principle of Justice.

    From the section “The Nature and Scope of Risks and Benefits”:

    “Risks and benefits of research may affect the individual subjects, the families of the individual subjects, and society at large (or special groups of subjects in society). Previous codes and Federal regulations have required that risks to subjects be outweighed by the sum of both the anticipated benefit to the subject, if any, and the anticipated benefit to society in the form of knowledge to be gained from the research. In balancing these different elements, the risks and benefits affecting the immediate research subject will normally carry special weight. On the other hand, interests other than those of the subject may on some occasions be sufficient by themselves to justify the risks involved in the research, so long as the subjects’ rights have been protected. Beneficence thus requires that we protect against risk of harm to subjects and also that we be concerned about the loss of the substantial benefits that might be gained from research.”

    That said I can understand why any particular IRB would tend to require that study participants (as a group) should expect to receive some benefit. (Note that understanding why IRBs would behave this way does not mean I agree that they should. I think they may be underestimating the costs – human costs and economic costs – that result from disallowing all human experiments with minuscule risks that provide no benefit to participants.)

  18. addisontree says:

    In the case of low power RF, even with the “do no harm” constraint we can still do experiments with low power RF on humans. We would just need to slightly reframe the experiment. Participants would be those who could benefit from more exercise and would be required to attend exercise classes three times a week. (America has many potential participants from which to choose.) Participants would also wear the headbands described above (some RF emitting, some just slightly heated, some completely inert). We can refine the details of the design as needed to address any lingering issues.

    Since the health risk to RF exposure (via the headbands) is tiny and the health benefit of the additional exercise is substantial all participants should expect an overall improvement in health at the start of the study. The study itself is measuring the impact of low power RF on the introduction of a healthy exercise regiment. However since we don’t really expect RF effects to be depend on the amount of exercise a person does, this revised study would be a good proxy for the original “no benefit” experiment described previously.

  19. Dagda says:

    @ addisontree
    The new study is as unethical as the old one.
    You don’t expect that the RF Frequencys do anything in combination with exercise, but why study it then?

  20. thequiet1 says:

    @ addisontree,

    Think of it like a catch 22; you want to do a study to prove something isn’t harmful, but if you don’t already have enough evidence to show it is not harmful then it is not ethical to perform with humans (or even with animals most likely). If you do have enough evidence to show it is not harmful then your study is superfluous as there would not even be a possibility of learning something new (unless you are trying to show the consensus is wrong and that RF really is harmful, in which case you are back at square one).

    You make a good point about the greater benefit to society that can come from subjecting a number of test subjects to possible harm, but when it comes to humans we set the bar extremely high. You could say that the rights of the individual are put before the benefits society may reap. This is a factor of our modern values; if we lived in a society like pre-modern Japan where the honour of of the empire was held far above that of any individual (think kamikazi, seppuku, ect) then you could probably justify many studies for the greater good.

    But as it happens we don’t live in pre-modern Japan, and if we would like to continue valuing individual freedom above all else we have to make some concessions, like not conducting experiments with no expectation of benefit for the participant in order to see if something is harmful.

  21. etatro says:

    @Mlema – Yes, my example was entirely fictional. I just wanted to find an example of an observational study that has some known & minimal risks as well as some known minimal benefits to the individual; but greater benefit to others. Then another example with putative greater risks with potential greater benefits (a drug the cure the flu). But with doing a placebo-controlled (blinded?) test in order to determine if something causes harm, we can’t do.

    @addisontree – In clinical research, despite the fact that we are doing studies in large numbers of people and in populations — and our data and conclusions are treated as aggregations or as application to large numbers of people (the “average” patient); we still treat individuals as wholly independent individuals. The benefits to society don’t matter and the care for the patient or study participant is considered above all else in deciding what to do.

    Regarding the Belmont report, and the Declaration of Helsinki. I do research at a university, and we are quizzed on them (I bet Steve is too) annually, in an ethical research conduct certification process. If you care to read the legalese & protracted governmentspeak on it, the NIH spells it all out on their website. http://grants.nih.gov/grants/policy/hs/ . I’m particularly attune to this topic because I just submitted a grant that was finally uploaded today (that involves human subjects). high five*

  22. Dirk Steele says:


    ‘I’m particularly attune to this topic because I just submitted a grant that was finally uploaded today (that involves human subjects). high five*’

    Congrats! I hope you will bear in mind this quote….

    ‘ More than 200 hundred years ago Johann Wolfgang von Goethe (1749–1832) warned: “I believe that in the end humanitarianism will triumph, but I fear that, at the same time, the world will become a big hospital, each person acting as the other’s humane nurse.”
    Moreover, Goethe foresaw the moral hollowness of the “humanitarian science” on which such therapeutic tyranny would rest: “I could never have known so well how paltry men are, and how little they care for really high aims, if I had not tested them by my scientific researches. Thus I saw that most men only care for science so far as they get a living by it, and that they worship even error when it affords them a subsistence.” ‘

  23. etatro says:

    I realize that I am continuing to post on an old thread. And I may be at risk of feeding the trolls.

    I am curious, though, as to what, specifically, “humanitarian science” or “therapeutic tyranny” are. I just want to be on the same page with you, here, because communication requires that we agree on the meanings of terms in the language. I find that people will make up multisyllabic terms for the purpose of wow-ing their communication partners and lend their statements either authority or mysticism. Giving you the benefit of the doubt — those terms are some sort of field-specific jargon that I’m not familiar with.

    At any rate, Dirk, this seems to be some sort of veiled accusation. I bear in mind lots of things when I carry out my work. Medical research in the US driven by lots of various competing factors, but I believe that, for all the ugly sausage-making and politics that is the process (and I have very much criticized it here), in the end we fund good projects and good scientists, toward goals make the human condition less short, less brutish, and less painful.

  24. YuliaZh says:

    Thank you, Dr Novella, it was extremely helpful! I was assigned an essay on pros and contras for cell phone use, and nothing like a good skeptical article to get you through a boring essay! 8))

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