NOTE: Orac is on semi-vacation this week, trying very hard to recharge his Tarial cells. Actually, although he is at home, he is spending much of his time in his Sanctum Sanctorum (i.e., his home office) working on an R01 for the February submission cycle. Given that the week between Christmas and New Years Day tends to be pretty boring, both from a blogging and blog traffic standpoint, he's scaling back the new, original stuff and mixing in some "best of" reruns, as well as some more recent stuff that appeared in a different form elsewhere, modified a bit to be more appropriate to this blog. Why? Because he likes them enough that he wants to make sure that as many people as possible see them.
Fear not, though. If something sufficiently interesting happens, Orac will welcome a break from the drudgery of grant writing to apply some appropriate not-so-Respectful Insolence to it. (Yes, I'm referring to Deepak Chopra, who, I'm told, returned over the weekend after Christmas, surpassing even his own usual level of vitriol towards "skeptics.")
It's been about a year and a half since I've written about this topic; so I thought I'd better update the disclaimer that I wrote at the beginning:
Before I start into the meat of this post, I feel the need to emphasize, as strongly as I can, four things:
- I do not receive any funding from the telecommunications industry in general, or wireless phone companies in particular. None at all. In other words, I'm not in the pocket of "big mobile" any more than I am in the pocket of big pharma.
- I don't own any stock in telecommunications companies, other than as parts of mutual funds in which my retirement funds are invested that purchase shares in many, many different companies, some of which may or may not be telecommunications companies.
- None of my friends or family work for cell phone companies.
- I don't have a dog in this hunt. I really don't.
There. That's better. Hopefully that will, as it did last time, serve as a shield against the "shill" argument, which is among the frequent accusations I hear whenever I venture into this particular topic area. So, as I did back in 2008, I just thought I'd clear that up right away in order (hopefully) to preempt any similar comments after this post. Unfortunately, as I have known for a long time, I'm sure someone will probably show his or her lack of reading comprehension and post one of those very criticisms of me. It's almost inevitable, either here or elsewhere. Posting such disclaimers never seems to work against the "pharma shill" gambit when I write about vaccines or dubious cancer cures. Even so, even after nearly ten years involved in skepticism and promoting science-based medicine, hope still springs eternal.
There are two reasons that I think the issue of mobile phones and cancer needs an update on our blog: First, it has been a year and a half since I last wrote about it. At that time I castigated Dr. Ronald B. Herberman, who at that time was director of the University of Pittsburgh Cancer Institute for what I viewed as fear mongering over cell phones and cancer based on at best flimsy evidence. Second, there have been two fairly high profile studies looking at whether there is a link between mobile phone use and cancer. One of these my colleague and friend Steve Novella has already discussed, but there was another one that he didn't see because it didn't get quite as much publicity, possibly because the corresponding author is based in Korea. I will take this opportunity to discuss them both.
Note: Given that Orac is on vacation (sort of) this week (in reality I'm spending a lot of time in my home office writing a grant), posting this week will be a mix of the old and new. I'll be reposting some Classic Insolence reruns interspersed with some new stuff as the mood strikes me. Full regular posting will resume on January 4. In any case, this particular post you may have seen in a different form in a different place, but if you haven't, it's new to you! I like it enough that I had to make sure that it appears here too.
Over the last several years, as cell phones have become not only ubiquitous but have morphed into in essence pocket computers with Internet connections, there has developed a cottage industry of cell phone "shields" that allegedly protect people from horrible microwaves emitted by cell phones that supposedly cause cancer. These shields, of course, do nothing of the sort; objective tests of many of them show that they don't even do a good job of blocking electromagnetic radiation emitted by cell phones. However, the data looking at the question of whether cell phones can cause some form of cancer has been mixed at best and consistent with no detectable association or possibly a very tiny association that just rises above the background noise, but even that is arguable.
One reason we have a lot of doubts over whether cell phone radiation can actually cause cancer goes back to a longtime focus of this blog and one reason why I try to emphasize science-based medicine rather than evidence-based medicine, namely scientific plausibility. From a biological standpoint, a strong link between cell phone use and brain cancer (or any other cancer) is not very plausible at all; in fact, it's highly implausible. Cell phones do not emit ionizing radiation; they emit electromagnetic radiation in the microwave spectrum whose energy is far too low to cause the DNA damage that leads to mutations that lead to cancer. True, it is possible that perhaps heating effects might contribute somehow to cancer, but most cell phones, at least ones manufactured in the last decade or so, are low power radio transmitters. It is also possible that there is an as yet undiscovered biological mechanism by which low power radio waves can cause cancer, perhaps epigenetic or other, but the evidence there is very weak to nonexistent as well. Worse, as has been pointed out many times, epidemiological evidence for people who have used cell phones heavily for more than 10 years is sparse.
Moreover, it's not possible to study the issue by randomized studies, because it is impractical to the point of being virtually impossible to randomize people into groups that do and do not use cell phones given how essential cell phones have become to most people in industrialized nations and then to follow them for the 20 years or so that it would take to identify a link. That leaves retrospective data, with all the perils and pitfalls inherent in retrospective studies. One potential approach to such a study is to formulate a simple hypothesis. If mobile phone use causes cancer, then after the widespread introduction of cell phones into a population there should be a detectable significant increase in the incidence of tumors that could potentially be due to cell phone use, particularly 10 to 20 years later. That is the hypothesis that the investigators who published recent Danish study (Deltour et al, Time Trends in Brain Tumor Incidence Rates in Denmark, Finland, Norway, and Sweden, 1974-2003) decided to examine. It is a good population to examine this question in because the populations of these countries is homogeneous, cell phone use became widespread earlier than it did in the U.S., and these countries have nationalized health systems that allow centralized collection of cancer data in national cancer registries.
The basic design of the study was as follows. Investigators examined the cancer registries of these nations for the first incidence of brain tumors in patients aged 20-79, noting this background:
Previous investigations in Denmark, Finland, Norway, and Sweden found that the incidence of glioma was relatively stable from 1983 to 1998 ( 7 ) and that the incidence of meningioma increased from 1968 to 1997, more so for women than for men (8). Time trends in brain tumor incidence after 1998 are likely to be relevant for evaluating possible associations with respect to radio frequency exposure from mobile phones after 5 - 10 years of exposure. We investigated time trends in brain tumor incidence rates in these four Nordic countries to evaluate whether trends in the incidence of brain tumor changed in Denmark, Finland, Norway, and Sweden from 1998 to 2003.
This information is important to know, because if brain tumor incidence were rising before the widespread use of cell phones, then to find a correlation that might indicate causation, there would have to be a more rapid increase in brain cancer, starting with an appropriate lag time after the use of cell phones became so prevalent, likely at least five to ten years. This is very much like the evidence for an epidemiological link between smoking tobacco and lung cancer, except that for the tobacco-lung cancer link there was a 20-30 year lag between the introduction of inexpensive, mass-marketed cigarettes and the increase in lung cancer incidence. In any case, the resultant population examined in this study was, in essence, the entire populations of these four countries, where 59,984 brain tumor cases that were diagnosed from 1974 to 2003 among 16 million adults aged 20 -79 years. They say that a picture is worth a thousand words; so here is Figure 1 from the paper:
Panels A and B present incidence rates for gliomas and meningiomas, respectively, in men; panels C and D present incidence rates for gliomas and meningiomas, respectively, in women. Circles indicate rates for those aged 20 - 39 years, squares indicate rates for those aged 40-59 years, triangles indicate rates for those aged 60-79 years, and a solid line indicates the regression curve. As described in the paper:
During this time, the incidence rate of cancers known as gliomas increased gradually by 0.5% per year among men and by 0.2% per year among women.
For cancers known as meningioma, the incidence rate increased by 0.8% among men and, after the early 1990's, by 3.8% among women.
This more rapid change for women was driven, the researchers say, by the 60-79 year age group.
In other words, there was a slow rate of increase in these tumors that did not change in the 1998-2003 cohort. The reasons for this slow rate of increase are unclear, but because it began before the widespread insinuation of mobile phones into the population it is almost certainly not due to mobile phone radiation. One possibility that could have contributed to this is the increasing use and sophistication of imaging technology like CT and MRI, which, as the authors pointed out in the introduction, can lead to an increased apparent incidence without any changes in etiological factors through the detection of asymptomatic meningioma, for example. (Sound familiar?) In any case, there was no detectable evidence of an uptick in the incidence of these brain tumors after 1998. The lack of evidence for a change in the rate of increase of these tumors is consistent with three conclusions. Either there is no link between cell phone use and these brain tumors; the "lag time" for such an effect is greater than 5-10 years; or the effect is too small to be detected in an overall population level. One area where I will disagree with our fearless leader (somewhat) is that I don't consider this study to be weak evidence. It is, in fact, strong evidence that, if a link between cell phone use and brain cancer exists, it is almost certainly weak and small. Add to that the biological implausibility of a link, given our current knowledge about cancer, and I remain less than impressed with the claims that cell phones cause brain cancer. I would be happy to change my mind if new evidence, either in the form of a biological mechanism being discovered that could explain how long term exposure to low energy radio signals could cause cancer or epidemiological evidence showing a clear association between cell phone use and cancer (preferably both), came to light.
Unfortunately, the second study does not qualify as either form of evidence. (How's that for a segue?) In fact, from my perspective, it is one of the best examples of how meta-analyses can be tortured to find tenuous correlations where none probably exist. The study, which appeared in the November 20 issue of the Journal of Clinical Oncology, apparently slipped by my notice when it first appeared as an online publication on October 13. In any case, the study (Myung et al, Mobile Phone Use and Risk of Tumors: A Meta-Analysis) is, as the title says, a meta-analysis, meaning it's a formal way of combining multiple studies that may or may not have statistically significant results on their own, that may or may not have found a correlation, and trying to see if the weight of the evidence suggests a correlation between mobile phone use and cancer. In this case, 465 articles were winnowed down to 22 articles using specific selection criteria, which were:
We included epidemiologic studies that met all of the following criteria: case-control study (to date, no randomized controlled trials and only one retrospective cohort study published in four different articles have been reported; therefore, we included only case-control studies in this study); investigated the associations between the use of mobile phones, cellular phones, or cordless phones and malignant or benign tumors; reported outcome measures with adjusted odds ratios and 95% CIs, crude odds ratios and 95% CIs, or values in cells of a 2(1)2 table (from which odds ratios could be calculated). If data were duplicated or shared in more than one study, the first published or more comprehensive study was included in the analysis.
I'll cut to the chase right now. This meta-analysis does not--I repeat, does not--show any correlation between cell phone use and cancer, at least not in the overall results. The authors even say so:
As shown in Figure 2, the overall use of mobile phones (use v never or rarely use) was not significantly associated with the risk of tumors in a random-effects model meta-analysis of all 23 case-control studies (odds ratio 0.98; 95% CI, 0.89 to 1.07).
Let me repeat that again. The overall meta-analysis did not find any significant association between mobile phone use and tumors.
Of course, whenever an investigator does a meta-analysis and finds a result like this, he can never rest there. He has to slice and dice the data to try to find a group for which there is a correlation. There's nothing wrong with that in and of itself. In prospective studies, post hoc subgroup analyses that were not planned in the original protocol right from the beginning are generally frowned upon because they have a high tendency to find associations that are usually spurious. I tend to look at it as being a lot like making multiple comparisons but not controlling for them. By doing a study to look at one population and a set of outcome measures but then, upon finding a negative result, going back and doing subgroup analyses, one is basically doing multiple comparisons without correcting for multiple comparisons. Anyone who's been a regular reader of this blog should know that if one doesn't correct for multiple comparisons, the more comparisons the higher the likelihood of finding one or more false positives.
Even so, it's not necessarily scientifically dubious to do subgroup analyses if one looks at it as a hypothesis-generating exercise, rather than any actual conclusions. Correlations that are found may or may not be "real," but strong correlations may be worth further investigation. What bothers me about this study is not so much that it did subgroup analysis on the populations studied, but rather how it did a sort of dubious "subgroup analysis" on the actual studies themselves:
However, a significant positive association (ie, harmful effect) was observed in eight studies 7,12,14-16,18,23 and one study by another group10) using blinding (odds ratio1.17; 95% CI, 1.02 to 1.36), whereas a significant negative association (ie, protective effect) was observed in 15 studies (nine INTERPHONE-related studies17,20-22,24-28 and six studies by other groups8,9,11,13,19) not using blinding (odds ratio 0.85; 95% CI, 0.80 to 0.91). No publication bias was observed in the selected studies (Begg's funnel plot was symmetric; Egger's test, P for bias .21; Fig 3)
[...]
Subgroup meta-analyses by methodologic quality of study revealed a significant positive association in the high-quality studies (odds ratio 1.09; 95% CI, 1.01 to 1.18), whereas a negative association was observed in the low-quality studies. In subgroup meta-analyses by malignancy of tumor, no significant association was observed for malignant tumors. However, a significant negative association was observed for benign tumors. Neither the use of analog phones nor the use of digital phones was associated with the risk of tumors.
First, note that these odds ratios are barely statistically significant, ranging from 1.02 to 1.36 and 1.01 to 1.18; in other words, the 95% confidence interval barely misses overlapping with 1.0. More importantly, I was very puzzled by the way that they chose to differentiate "high" quality studies from "low" quality studies. Basically, although it is only one of the eight criteria used in the Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Case-Control Studies to evaluate study quality, for some reason the Myung et al decided to focus primarily on whether the studies were blinded or not, specifically whether the status of patient cases and controls was blinded at interview (blinded or not blinded/no description). This struck me as most curious. So studies that were blinded showed a positive association between cell phone use and brain tumors upon meta-analysis of just their results. The authors also report that their subgroup analysis demonstrated that studies of higher methodological quality (greater than or equal 7 points) also showed a positive association between cell phone use and cancer for just these studies.
So does it mean anything that lumping the studies together that are of "high quality" produces a positive result where the low quality studies don't? Normally, I'd think that it might. After all, the studies showing the positive result are considered to be methodologically rigorous, although it should be noted that several of them individually didn't find a significant association. In this case, I doubt it means much of anything, and here's why. Seven of the eight "high quality" studies were all by a single group of researchers, Dr. Lennart Hardell's group in Sweden. Whenever one group of researchers keeps finding a result that no other group seems able to replicate or that otherwise disagrees with what everyone else is finding, that's a huge red flag for me. Remove those studies, and even the wisp of a hint of a shadow of the association between cell phone use and cancer found in this study disappears. I'd have a lot more confidence in this seeming association in "high quality" studies if the association didn't depend upon a single researcher and if this researcher was not also known for being an expert witness in lawsuits against mobile phone companies. Don't get me wrong; these studies could be correct, but replication is one of the checks on research in science-based medicine. If other groups can't replicate Dr. Hardell's work, I wonder why. Is it something about the methodology? Is it something specific about Swedes? Is it something about the population? Are there confounders unique to his work that aren't operative elsewhere? Until I see other researchers independent of Dr. Hardell and using a variety of different analyses find the same results, I don't have a lot of confidence in them. Even the authors acknowledge that a weakness of their study is that "we did not explore potential confounding factors in the studies by Hardell et al that reported positive results not found by other study groups."
There was another passage in this paper that I also found most curious:
We feel the need to mention the funding sources for each research group because it is possible that these may have influenced the respective study designs and results. According to the acknowledgments that appeared in the publications, the Hardell et al group was supported by grants from the Swedish Work Environment Fund, Orebro Cancer Fund, Orebro University Hospital Cancer Fund, and so on. Most of the INTERPHONE-related studies were mainly supported by the Quality of Life and Management of Living Resources program of the European Union and the International Union Against Cancer; the International Union Against Cancer received funds for those studies from the Mobile Manufacturers Forum and the Global System for Mobile Communication Association.
I don't know about you, but I've never seen a passage like this in a research paper or meta-analysis before. It stands out like the proverbial sore thumb, and I can only think that it was placed there to try to cast aspersions, representing Dr. Hardell as the exemplar of Truth, Justice, and Science while painting the studies that failed to find an association between cell phone use and cancer as hopelessly biased, the product of Big Cellular. At least that's how it came across to me. It struck me as gratuitous.
So where do we stand now? My interpretation of the evidence thus far is that we can say with some confidence that there is no short term risk of brain cancer from cell phone use. However, after more than ten years the evidence is less clear but trends towards either no detectable risk or a very small risk that barely rises above the noise. It's possible that there may well be a risk; it's possible that there is hitherto undiscovered biology that provides a mechanism by which non-ionizing radiation like the radio waves from cell phones could over time induce cancer beyond ten years. Because more and more people are using cell phones over longer and longer periods of time, it's worth studying this issue. If there is an increased risk, it may be possible to mitigate that risk by using headsets or through the design of phones that use less energy. Mobile phone technology is a relatively new technology, though, and has only been widely available since the mid-1990s. In the U.S., it didn't become truly ubiquitous until the early part of this decade. Consequently, there hasn't been enough lag time for us to be truly confident of studies showing little or no risk. On the other hand, it is reassuring that early studies are pretty resoundingly negative and that there really is no good biological mechanism that we have been able to find by which cell phone radiation could cause cancer. In the next 5-10 years, more studies will be done, and, over that time, I expect evidence will answer the question one way or the other.
In the meantime, it's useful to keep things in perspective. Each and every year, there are approximately 40,000 to 45,000 fatalities due to auto collisions. Getting in a car and driving to work every day is among the most dangerous things the average person does. Yet we accept this risk because automobiles are such an incredibly useful tool in modern life; indeed, they are indispensable to most people. Cell phones are clearly in that category as well; so even if cell phones are ultimately found to increase the risk of brain cancer by, for example, 10-20% after 10-20 years, it would most likely be a risk that most people would end up living with in order to be able to use these incredibly useful devices. My personal reading of the data is that there probably isn't a significant risk of brain tumors due to the use of cell phones, but I am not sufficiently certain to make any blanket statements. I, like everyone else, will have to wait for the evidence to settle things one way or the other.
REFERENCES:
Myung, S., Ju, W., McDonnell, D., Lee, Y., Kazinets, G., Cheng, C., & Moskowitz, J. (2009). Mobile Phone Use and Risk of Tumors: A Meta-Analysis Journal of Clinical Oncology, 27 (33), 5565-5572 DOI: 10.1200/JCO.2008.21.6366
Deltour, I., Johansen, C., Auvinen, A., Feychting, M., Klaeboe, L., & Schuz, J. (2009). Time Trends in Brain Tumor Incidence Rates in Denmark, Finland, Norway, and Sweden, 1974-2003 JNCI Journal of the National Cancer Institute DOI: 10.1093/jnci/djp415
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I think it might be a good thing if people go on "believing" that cell phones can cause brain cancer--then maybe they will quit using them in their cars all the time--which is increasing the REAL risk of dying in a car crash. I have had enough close calls recently to seriously consider moving to a city with decent transit so I can quit driving. There IS real and growing evidence that cell phone use causes car crashes (even when not hand-held).
"One reason we have a lot of doubts over whether cell phone radiation can actually cause cancer goes back to a longtime focus of this blog and one reason why we emphasize science-based medicine rather than evidence-based medicine, namely scientific plausibility."
That's one reason I love this blog as well! One of the most obnoxious things about arguing with denialists/creationists/etc. is that they seem far too willing to accept the most outlandish idea as long as it's anti-big pharma/Darwin/etc. Yes, I suppose there is the most infinitesimally small chance that vaccines cause autism, on the other hand it goes against everything we already KNOW about vaccines, namely that millions and millions die without them. In that case, I go with what we know, not what non-experts think might be possible.
"I think it might be a good thing if people go on "believing" that cell phones can cause brain cancer--then maybe they will quit using them in their cars all the time--which is increasing the REAL risk of dying in a car crash."
While I can agree that usage of cell phones has gone overboard, I don't think it's a good thing at all for people to believe in things if there's no evidence. It is awfully tempting to say so though and it could even have good consequences (for traffic safety, like you mentioned). It's just plain wrong for people to believe in things when there's no evidence for it. For you and me, and perhaps most of Orac's readers, it's not really a concern. But a lot of people need to learn to stop believing in all kinds of nonsense: don't believe in things concerning health if there's nothing to support it. Some people just need to get into that habit.
The really weird thing in this case is that the people who made the most money out of this scare are telecom companies.
They suddenly started offering shielded or less powerful phones. Scared people bought them even though their present phones worked just fine, with of course the strings of restrictive and expensive contracts attached.
I had an analogic cell phone which could transmit just fine in the middle of nowhere where the up-to-date less powerful digital ones could not.
And I agree about them being quite a danger on the road, handheld or not. But for some reason people are much less scared about dying or getting maimed in a car crash than they are of cancer, just like they are more concerned about infinitesimal levels of pesticides in their foods than they are about things like acrylamide or afflatoxin which are really powerful naturally occuring carcinogens found in everyday foods.
I think it's the illusion of "control" as in, "I can avoid dying in a car crash if I'm careful enough".
I see the nonsense is spreading, with Maine now considering a mandatory warning label on cell phones.
"But Dad, the other kids were doing it" doesn't cut it as an excuse - it certainly should not be a basis for legislation.
Hardly surprising; if the shields worked, your phone wouldn't. It couldn't get a signal.
Ah, but the difference here is that cellular phones are indicted as a culprit in collisions; boneheads texting-while-driving are ending up in ERs and morgues all over the world. Sadly, they often end up taking innocents with them as well.
Anent the phone/cancer link in general - it's worth mentioning that cordless phone handsets, such as the ones most people have at home, also us RF energy, and at higher frequencies than those employed by cellular phones, at least in the US. 2.4 GHz is well into the microwave spectrum and up to three times the frequency of a cellular phone.
Many people in the ham radio community use low frequency radio signals all the time. I don't know how the radio frequencies used by cell phones compare to the ham bands in question, but if the two are comparable one would think the cancer rate of the ham community (which AFAIK is not disproportionately high) would provide a useful checkpoint.
One comment: although a single microwave photon won't ionize anything, the photons from a mobile phone are emitted in a coherent state and so they can be absorbed "in bulk". In principle I can imagine them having all sorts of chemical effects (other than those caused by simple heating) despite the low energy of a single photon. The idea of some sort of biological effect does not seem a priori unlikely to me. However, I agree completely that the evidence is against any effect on humans.
I'm not a chemist; if I'm wrong about this, I'm happy to be corrected.
@8
The thing is that you need a certain energy level in the radiation for a chemical reaction - ionisation - to occur.
Ionisation consists of ripping electrons off an atom. Electrons can occupy only certain discrete energy levels in an atom - orbitals - which have nothing whatsoever in common with planetary orbits. They can jump up and down levels by receiving or emitting photons - particles of light- according to their energy levels (frequency). That's the actual meaning of the word "quantum", and an actual consequence predicted and explained by quantum theory.
Not enough energy means no absorption of the radiation to effect electronic transition and therefore no effect on ionisation. Its an all or nothing thing. That electron cannot absorb part of the energy for the next level in a photon and the remainder in the next, because that intermediate level is forbidden.
The coherence of radiation (as in a laser) does not affect the energy level of photons - and therefore it does not influence its capacity to ionize atoms. It does however influence its capacity to produce heat spots, which we can readily observe.
I remember seeing some of the initial buzz about this issue in the news, and hearing one talking-head Doctor on TV reply when asked : "It does . . . in advance of the studies, I'll tell you it does "
So in other words Dr Talking Head was flying off into non-science land and making a sweeping pronouncement without any science behind it.
If there were a corellation between ham radio and cancer, that would be very interesting, in particular becasue David Reynard, who brought (and lost) the first celphone suit and who so famously appeared on Larry King to denounce Motorola, is a ham operator. Ooops.
No. Mobil phones contain simple transmitters, not masers, so the light is not even close to coherent in the sense you are talking about. (they are relatively narrow band, allowing coherent reception of the signal, but the bandwidth relative to the frequency is pretty large compared to a laser or maser.) Additionally, the effect you seem to be alluding to, multi-photon ionization, requires extremely high energy densities. These effects are noticeable using lasers because we are really good at making extremely short pulses of light that are packed with tremendous amounts of power (many kilowatts). Additionally, we can focus the lasers to near diffraction limited spot sizes to create even higher energy levels. In short, you would never be able to pull this feat off with a basic cell-phone transmitter putting out a few measly milliwats of power in its pulses. Especially when those wimpy little pulses are not focused into your head, but are instead radiated outward and decaying in a square law fashion.
@ tl (12)
Don't forget that the energy of a photon at cell phone frequencies is around 10 ueV (microelectronvolts). The energy of photons causing ionization in living tissues are in excess of 1eV. Because the total energy of the photons in a multiphoton ionization event must be equal or greater than that of ionization, the number of photons required is at least in the tens of thousands, probably millions.
The probability of 10,000 photons causing ionization is vanishingly small.
Thanks for sharing! I really get a lot of new point of view from this article on the relationship between cell phone and cancer.
Thanks for all the helpful replies (to my question at #8). I asked it because I am used to thinking of microwaves in a classical sense. It seems to me that at a high enough intensity the electric field strength of the microwaves will be enough to overcome the atomic electric fields holding the electrons in place, and the atom would therefore be ionized. However, having done some sums it is now clear that the field strength of the microwaves produced by a mobile phone is nowhere near enough to pull electrons off directly, as several of you have pointed out. I should have checked this myself in advance.
Despite this, could there not be some other effects? The microwaves will cause currents to flow, which will lead to heating. Averaged over volume the temperature increase is tiny. However, if the currents are localized in just one part of a molecule, that part might get "hot" enough to allow a reaction to take place that would not normally happen.
Once again, I am not arguing that such effects occur. I am simply curious as to whether they really are as implausible as some of you seem to think! Anyway, thank you all again.
nd writes:
I'm not an expert, but just off the top of my head I'd guess any local heating effects would be no greater than, and perhaps less than, those due to variations in local blood flow caused by ordinary daily physical exertion or use of various portions of the brain.
If the microwave heating impacts were significantly greater than such background effects, I'd think after a while you might smell meat cookin'.
Jud (#16): not quite my point. Averaged over the volume of brain tissue exposed to the radiation the heating effects are indeed tiny, even less than the normal temperature variation within the brain. However, I was wondering whether the current flow causing the heating might be significantly non-uniform on a molecular scale. Perhaps this could happen if one particular branch of one type of molecule is much more "conductive" than the rest of what's in your brain. The average temperature rise would still be less then one degree, but locally within the conductive region the effects could potentially be much greater than this average figure would suggest.
I repeat that this is pure speculation on my part; I'm happily writing this on my wi-fi enabled laptop while the phone in my pocket is downloading email! I am simply curious about whether what I am suggesting is at all plausible.
The probability of 10,000 photons causing ionization is vanishingly small.
The point about the low probability of multiphoton ionization is perfectly correct. However, the microwave photons emitted from a cell transmitter are just as coherent as those emitted from a maser or laser. It's very easy to make coherent EM radiation at low frequencies (gigahertz or below) - any antenna will do it.
In principle there is some possibility of microwaves altering the conformations of proteins. For instance, microwave ovens are tuned so that they excite a particular rotational transition of the water molecule to maximize the absorption of the microwaves in organic material (largely water). But usually conformation change in proteins is associated with high temperatures - think of frying an egg - since the surrounding water rapidly carries away any energy input.
If it were, oughtn't it show up in Deltour et al.'s study?
#19
The frequency of the waves in a microwave oven has nothing to do with resonance. From Wikipedia:
Microwave heating is sometimes explained as a resonance of water molecules, but this is incorrect: such resonance only occurs in water vapor at much higher frequencies, at about 20 GHz. Moreover, large industrial/commercial microwave ovens operating at the common large industrial-oven microwave heating frequency of 915 MHz, also heat water and food perfectly well.
I belive that the entire hypothesis arose because of the death of the Republican political strategist (and apparently cell phone early adopter and heavy user) Lee Atwater at the age of 40 from a brain tumor. Because at least one celebrity cell phone user died of an aggressive brain tumor, the suspicion in some people's minds of a causal connection will be more difficult to expunge than a brain tumor itself...
If heating the skin on our heads were leading to brain tumors none of us could go out in the sunshine without developing gliomas.
That's always the way it is, isn't it? It always makes my jaw drop when people say that herbal supplements are a threat to Big Pharma. Um, no, the supplement market is a huge opportunity for Big Pharma to increase their revenue via a whole new product that has an obscenely high profit margin, can use much of the same equipment and distribution channels, and best of all requires no government oversight or testing.
So unless Big Pharma is a-scared of profit...
The thing that makes the cell-phone = cancer hypothesis seem incredibly implausible to me is the inverse square law.
Specifically, if the hypothesis were true, surely we would expect cell-phone induced cancers to happen vastly more often in the portions of the brain directly adjacent to the ear?
Because it seems like something like that would be blatantly obvious.
Reminds me of a friend who was convinced high-voltage power lines caused cancer, because a number of horses owned by one guy in Canada contracted cancer and their land had high-voltage lines running over it. Since (he said) horses rarely get cancer, obviously it must be due to the power lines!
Inverse square law mean little in this instance since the head is within the near field of the phone's antenna (for typical cell freqs: wavelengths between about 15 and 40 cm). The intensity of the E and H fields is more relevant. It's still very weak, and also variable since the phones get their power negotiated down depending on base station reception.
Power absorbed by the head has to be low regardless, which you can test by turning your body in a circle while you're on the phone (ok, it is hard to watch the reception bars while the phone is against your face, so try this with the phone against your chest). If absorption were significant you would expect significant attenuation when your head/body is between the phone and the tower. Doesn't happen.
It's also good that neural pathways are poor antennas, otherwise lightning strikes in cities would kill thousands.
I have established a web site that contains a wealth of "evidence based" scientific information on the topic of EMF and Health (www.emfandhealth.com). It contains much original material and references on the points raised in the original post as well as reader's comments. One page on the web site addresses the body of research done "in vitro" on various cell cultures which have been exposed to varying levels of EMF (http://www.emfandhealth.com/In%20Vitro%20Studies.html). Questions such this one from Orac are addressed by in vitro studies: "it's possible that there is hitherto undiscovered biology that provides a mechanism by which non-ionizing radiation like the radio waves from cell phones could over time induce cancer it's possible that there is hitherto undiscovered biology that provides a mechanism by which non-ionizing radiation like the radio waves from cell phones could over time induce cancer." Virtually all known carcinogens produce effects that have been detected in vitro. The mechanism is usually found much later. The overall conclusion to date according to the SCENIHR scientific committee of the European Commission is: "It is concluded from three independent lines of evidence (epidemiological, animal and in vitro studies) that exposure to RF fields is unlikely to lead to an increase in cancer in humans." In other words, the many rigorous in vitro studies to date have not shown any significant genotoxic effects.
I think the issue is trying to find a link to cancer. It seems to be very hard to re-create the situational effects of cell phone use and cancer is a long term effect caused from a multitude of things that have gone wrong in the body over time. I am a marketer for a company who promotes education on EMF safety. There have been studies done in the past that show DNA damage from low levels of microwave radiation, which is what a cell-phone uses. Dr. Henry Lai and Dr. Neil Cherry are good ones to look up. Dr. Neil Cherry spent his career studying the EMFs in nature and there is a huge difference between what we are exposed to in nature and the man-made frequencies we are exposed to. It is important to remember that our bodies are electrical in nature and thus respond to the frequencies around us. Even if there were no studies done on this issue, I would be convinced there was a problem because I have met many people who feel adverse effects when putting a cell phone to their head or get strange sensations when exposed to other EMF emitting devices. It is called Electro Sensitivity. A doctor cannot diagnose a person with this in the U.S. because there is no ICD-9 code for it so they hand out crazy diagnoses of anxiety or stress and give them a pill and send them on their way. There are other countries where Electro Sensitivity is common and you are aloud to talk about it without being called a lunatic and having your license stripped away. This is a real illness and their are a lot of people who have it. It amazes me how primitive our society is but yet we are so smart. The electrical system in our bodies might be one of the most important factors in our overall health and it very well could be the most important factor in our health. If our cells are communicating by electrical impulses and we are constantly being exposed to electrical fields what is this doing to our cell to cell communication? Every person has what is called a bio-field. This is something that has been known in Chinese medicine for thousands of years and was recently accepted and named by the World Health Organization. It is the electrical field that is emitted by the human body. Now, if you go into a hospital and have to turn your cell phone off because it can interfere with the medical equipment in a hospital or interfere with someone's pace maker, it makes total sense that constant exposure to EMFs would interfere with our bodies. Most people do not think of themselves as energy or as electrical in nature, but we are. With all the cell masts going up and all the wi-fi and all the cell phones around us we are essentially living in a toxic environment and children are now growing up in this environment from the day they are born. If the jury is still out scientifically on what this is doing to our health, logically you have to see there is a problem with this. Everyone keeps talking about cancer, but you cannot study the cancer effects, it is too long term. I guess the only way to know is to create an environment where we are being exposed constantly to abnormal electro magnetic fields and see what happens. Hmmm? That sounds intelligent. Let's just wait and see if it might be safe. If you have children, which I don't, you should be pissed that your children are part of the largest global experiment ever. If you have children, your wait and see attitude is just plain amazing to me. But let's wait and see what the scientists find out ten years down the road. If your microwave was running on a very low energy would you stick your head in it? A cell phone works on low frequency microwaves.
The glib declaration reeks, "I would be happy to change my mind if new evidence, either in the form of a biological mechanism being discovered that could explain how long term exposure to low energy radio signals could cause cancer or epidemiological evidence showing a clear association between cell phone use and cancer (preferably both), came to light."
Seems like nonsense to me: "if one doesn't correct for multiple comparisons, the more comparisons the higher the likelihood of finding one or more false positives."
"I don't know about you, but I've never seen a passage like this in a research paper or meta-analysis before. It stands out like the proverbial sore thumb, and I can only think that it was placed there to try to cast aspersions, representing Dr. Hardell as the exemplar of Truth, Justice, and Science while painting the studies that failed to find an association between cell phone use and cancer as hopelessly biased, the product of Big Cellular. At least that's how it came across to me. It struck me as gratuitous." -- anyone even vaguely familiar with the history of the cell phone industry & its relation to research that risked jeopardizing it would know why the sore thumb is sticking out; you must read insider star Motorola man Robert C. Kane's condemnation ('01) for some background at http://www.scribd.com/doc/21783803/Cellular-Telephone-Russian-Roulette , and now a recent piece, at long last a topical quality one in the mainstream, at http://www.gq.com/cars-gear/gear-and-gadgets/201002/warning-cell-phone-… . Then e.g. you must consider the tripping up of Henry Lai in the 90s with his finding of DNA breaks now copiously re-verified, and how funding was made scarce for the "wrong" kind of studies & duplication attempts, how Lai turned to study the studies and saw a serious skewing based on study backing...
And just why the overfocus on cancer, just why? For determination of public policy, esp. given the well-recorded, if mostly buried, history of American-led malfeasance regarding RF use, much more sensible would have been to heed the old Soviet method of determining safety levels, which latter were set 1000x lower. They listened to how people actually said they felt, and wisely assumed cumulative effect. Here's Paul Brodeur from his '77 masterwork in the field:
.......
In light of what is now known about the biological effects of microwave radiation, Dr. McLaughlin's observations in the so-called California case in 1954, together with the eminently sensible recommendations he made in 1962, fairly take one's breath away [he expressed the need for great caution, incorporating differences in frequencies, body parts, time periods, cumulative absorption, penetration, etc. vs treating the body and the spectrum mostly as undifferentiated lumps]. What happened, then, as a result of these observations and recommendations? Nothing. Why? Dr. McLaughlin's fellow physicians and scientists---both military and civilian---decided at the time of the first Tri-Service Program that the California case could be dismissed either as unproved or as involving gross heating of the hollow viscera, and that Professor Schwann's whole-body heat dissipation theory and the ten-milliwatt standard would take care of everything.
.......
"undiscovered biology" -- how widely has orac considered in the field of discovery? -- not very far, we'd guess; for a latter day biologist speaking out (notably upon retirement...), see Andrew Goldsworthy on "mechanism by which non-ionizing radiation like the radio waves"...
"40,000 to 45,000 fatalities due to auto collisions" -- a more cognate concern re RF exposures in comparison with autos, would be, say, the lung/respiratory-damaging effect of allowing the internal combustion engine to rule: we've sacrificed some lung capacity, but must a human not draw a line when it comes to the brain?
"Cell phones are clearly" NOT "in that category as well" of indispensibility. Further, by what public policy calculus would you propose to irradiate non-user me & family via ubiquitous cell mast antennae, just so you could so indispensibly make a basement garage phone call of most likely frivolous content at all hours of the day?
"but I am not sufficiently certain to make any blanket statements" -- insurance companies pulled out long ago, and while you won't easily find topical "blanket statements" from them, if their reticence doesn't tell you something important, your unfamiliar blog, which i was just directed to with the challenge, "If you do manage to visit Oracâs and out-debate him (or, if he is not an expert in the field though he seems to be to me, if you out-debate whichever expert he defers to), you stand a very good chance of convincing me, at which point Iâll print a public retraction on everything Iâve said, and Iâll show up at council meetings and vociferously petition to stop the Eastlink tower thatâs now going up [...]", your blog i should revert to ignoring, except to worry how you might lead impressionable others astray
What I want to know is why this "surgeon/scientist" would discount brain surgeons crying out about cell phones based on what they are facing, and why the overfocus on cancer, when myriad other ailments or their serious & progressive exacerbation are plausibly attributable to exposure to microwaves?
Name two.
Show that RF energy at the frequencies and power levels radiated by an FCC approved cellular device (or any properly operating device found in the home) meet or exceed these levels.
Sorry - hit 'Post' too soon -
please add
... needed to cause those ailments.
Of course, if you're a homeopath, and you invert the dose/response curve, you might be on to something.
"Name two."
So dares Johnny.
OK. I'm in Canada. The leading (married) pair of one federal political party, the NDP, was in the news between your post & this. About what? The party leader's just-diagnosed prostate cancer, with all the attendant typical culturally dominant calls to "battle" this and "fight" that, bizarre talk about inherited prostate cancer.
And the spouse herself had earlier been a thyroid cancer patient.
If there are ailments of two parts of the body among the most closely associated with wireless misuse, it is they, prostate & thyroid. Affliction in both has shot up right from the late 90s mass proliferation. And politicians like those would be prone to be among the busiest users of cell telephony & associated wireless.
What do insurance companies know that you turn you head away from?
Correlation & causation...they're not the same.
The apparent incidence of prostate cancer has decreased significantly from the early 90s (source). This is really a result of a damatic rise in the apparent incidence from the approximate 1989-1992 period, which was due to the use of new diagnostic tests, particularly the PSA. That the apparent incidence fluxuations don't indicate a substantial change in the real incidence is the conclusion suggested by relatively unaltered prostate cancer mortality rates (source).
If it was this easy to poke a hole in your argument, Daryl, maybe you need to go back and be sure that your claims are supported by actual data...?
Start here regarding thyroid cancer: Thyroid Cancer's Rising Incidence: Reality or Illusion?
...then, evaluate whether a cell phone hypothesis is even necessary to explain your claims.
That was a "hole"? There was not even an "argument". Do some of us need lessons in careful scrutiny & rationality?
But I took your lead and followed the thyroid thing. And you figure that that is a definitive debunking of claims about thyroid incidence?! Autopsies show lots o' mini-cancers, and you can't see the tentative conclusion can be, that there are in fact many more such cancers?
I'm sorry, 'tizzie, but I don't fall into the cancer analysis trap when figuring about public policy anyway. You must show the wisdom in such a focus, waiting out latency periods in the culture of get-away-with-what-you-can and i-don't-care as predominating livelihood basis.
In fact, to offset that sorry public policy context and nonsensical media going along, anecdotal evidence should offer some counterbalance. But one has to not turn away from listening or looking. I know two fairly youthful prostate- and thyroid- afflicted. I know about the wireless dependencies. I've read surpassingly much damning the industry inside out.
And the thyroid article even carefully quotes, ""My concern is that if we blame this entirely on early detection, we may be missing some other cause of thyroid cancer," he says. "I don't think any of the data we have rule out some other etiology."" So what's your own "argument"?
On your side, but only sort of, dental x-rays were omitted from the article. "Sort of", because of being stuck on the daffily rigid distinction of radiation ionizing from non-.
The prostate links & their links are too complex for a quick reply. And they are less interesting and potentially distracting than a boatload of other info.
This blog is so queer my dead cat could write sometin betta. Cell phones are off da hook yo. No brain cancer for me dawg.
Daryl,
Your post is old, but worthy of a current response. I propose that the culpret to any rise in cancer rates (any cancer type) among a population group is directly related to that groups use of chemicals in daily life. The tens of thousands of chemicals in use today will have caused far more harm than any radiation produced by modern electronics, and I'm including high-power transmission lines here. PCB's have been banned (in most forms) for quite some time and are still having a severe affect on aquatic organisms. That's one out of thousands.......