I’ve caught some flak before over things I’ve written about the almost certainly nonexistent link between cell phones and cancer. Actually, it’s not the kind of flak you probably think, unless you’ve been a long time reader and remember the relevant posts. You’d think it would be believers attacking the mean old skeptic for denying a link between cell phone radiation and cancer, thus making me (obviously) a shill for big telecom. Actually, it was flak from one physicist and at least a couple of skeptics, who didn’t like that I actually left open the small possibility that it could be possible that there is a link. The problem that irritated the crap out of me was not so much that these skeptics make the argument that it’s physically impossible for cell phone radiation to cause cancer. A viable argument to that effect can be made based on how low the energy emitted by cell phones is. No, what irritated the crap out of me is that they made these arguments based on a painfully simplistic view of how cancer originates in which they assume that it’s physically impossible for something to cause cancer if it doesn’t break chemical bonds, which is an idea that’s so 1990s. There’s so much more to carcinogenesis these days than breaking chemical bonds in DNA and causing mutations. There are metabolic changes, epigenetics, and potentially a whole host of other mechanisms that we don’t understand yet, and, unfortunately, these dismissals of a possible link were often based on a high school level understanding of cancer biology.
Still, despite my trying to keep an open mind on the matter, I also don’t want my mind to be so open that my brains fall out, so to speak. Even accounting for the newer, richer, and more complex understanding of carcinogenesis that has emerged over the last decade, I still have to concede that, from a strictly physical, physics- and biology-based perspective, given the low energy emitted by cell phones, the chances that they can do anything to cells that would result in cancer are vanishingly small, Thus, a link between cell phones and cancer is incredibly implausible from a strictly basic science point of view. Not homeopathy-level implausible, admittedly, but nonetheless mighty implausible indeed. Nor is the epidemiological evidence particularly convincing, as I’ve discussed in my usual Orac-ian prose time and time again. Basically, the only suggestive studies all come from the same group in Sweden, which is always a red flag to me (that the studies all come from one group, not that they come from Sweden, I hasten to add). As I said before, 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 problem. I’d also 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.
All of which leaves me very puzzled by the lastest news stories I’m being bombarded with by my readers:
- Cellphones are dangerous/not dangerous: the WHO changes its mind
- Experts say cellphone use could cause cancer
- WHO: Cell phone use can increase possible cancer risk
- World Health Organization Unit Warns Cellphones May Cause Cancer
- Cell Phones May Cause Cancer, Says the WHO. What to Do?
And that’s just a sampling of the articles about this report by the World Health Organization’s International Agency for Research on Cancer (WIARC). Actually, it’s not a report. it’s a press release. The actual report is scheduled to be published in the July 1 issue of The Lancet Oncology and “in a few days online.”
My first thought in reading about this was to wonder what these guys are smoking. After looking at the press release, my thought was that this is a perfect example of how the paradigm of evidence-based medicine, in which epidemiology and clinical data always trump basic science considerations, even when they are quite firm in their conclusions that a link between an environmental factor and a health outcome is as damned near close to impossible as the proposed link between cell phone radiation and cancer is based on pure physics. The press release describes its results:
The evidence was reviewed critically, and overall evaluated as being limited2 among users of wireless telephones for glioma and acoustic neuroma, and inadequate3 to draw conclusions for other types of cancers. The evidence from the occupational and environmental exposures mentioned above was similarly judged inadequate. The Working Group did not quantitate the risk; however, one study of past cell phone use (up to the year 2004), showed a 40% increased risk for gliomas in the highest category of heavy users (reported average: 30 minutes per day over a 10‐year period).
And its conclusions:
Dr Jonathan Samet (University of Southern California, USA), overall Chairman of the Working Group, indicated 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.”
“Given the potential consequences for public health of this classification and findings,” said IARC Director Christopher Wild, “it is important that additional research be conducted into the long‐ term, heavy use of mobile phones. Pending the availability of such information, it is important to take pragmatic measures to reduce exposure such as hands‐free devices or texting.”
Funny that Dr. Samet should mention texting. The only verified danger of using cell phones thus far is the increased risk of getting in an auto crash due to the use of cell phones while driving. Be that as it may, what is the “2B classification“? Basically, it means “possibly carcinogenic to humans,” more specifically:
This category is used for agents for which there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals. It may also be used when there is inadequate evidence of carcinogenicity in humans but there is sufficient evidence of carcinogenicity in experimental animals. In some instances, an agent for which there is inadequate evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals together with supporting evidence from mechanistic and other relevant data may be placed in this group. An agent may be classified in this category solely on the basis of strong evidence from mechanistic and other relevant data.
There are a lot of problems with the claim that cell phones cause cancer, not the least of which is that the science and epidemiology just don’t support it. In particular, the INTERPHONE study, whose results were reported last year, showed no evidence of a link between cell phone use and glioblastoma or meningioma. In fact, to me the decision by WHO is exceedingly puzzling because, if anything, over the last several years the evidence has been trending more and more towards being inconsistent with with a link between cell phone use and brain cancer–or health problems of any kind, other than getting into car crashes because of texting or talking while driving. I note that the INTERPHONE study relied on a dubious subgroup analysis in order to find that there was a 40% increased risk of glioma in the very heaviest users of cell phones that only barely achieved statistical significance and no increased risk of meningioma. Moreover, as I pointed out a year ago, among the heaviest users were reports of implausible levels of cell phone use, as high as 12 hours per day, every day. When a different method of quantifying cell phone use–asking how many calls per day a person typically made–was used, the increased risk of cancer disappeared.
I also note that a brand new study was just published in the American Journal of Epidemiology that doesn’t support the hypothesis that cell phone radiation causes brain cancer, either. The study, out of Finland, bases its hypothesis on the simple physical observation that cell phone energy absorbed from the radio field created by cell phones depends strongly on the distance from the source. As a result of this known relationship, an obvious hypothesis is that, if cell phone radiation causes brain cancers, then one would expect that the brain tumors resulting from the exposure would cluster closer to where the phone was held. In other words, if a person holds his or her phone more on the right than on the left, then one would expect that any resultant tumors would be on the side where the phone was most commonly held more often than random chance alone would predict. The stronger the carcinogenic effect, the more likely it should be for tumors to be found on the side. So the investigators did a fairly complicated analysis in which they tried to correlate laterality of cell phone usage with locations of brain tumors in 888 INTERPHONE subjects.
Guess what they found?
Nothing. Nada. Zip. No spatial correlation between cell phone use and the locations of the brain tumors observed. Using one form of analysis, the investigators found that tumors were located closest to the source of exposure among never-regular and contralateral users, while in another analysis there was no correlation between where a user held his or her phone and where subsequent brain tumors arose. The authors concluded:
In conclusion, the results do not indicate that gliomas are located in excess in the brain tissue presumably receiving the highest-intensity electromagnetic field among regular mobile phone users. Cumulative call time, duration of use, and laterality were not consistently associated with the location of the gliomas.
When considering evidence for a link between an environmental exposure and a cancer, it is important to consider all the evidence. First, there must be biological plausibility. A cell-phone brain tumor link is highly implausible based on physics alone, but probably not impossible. Even in the case where a mechanism is not known, compelling epidemiological evidence can overcome that; such evidence does not exist for a cell phone-cancer link; even the WHO doesn’t claim that. Among the evidence that should exist is a relationship between the environmental exposure and cancer that makes sense scientifically for the specific exposure. In the case of cell phone radiation, this means that the laterality of brain cancers should correlate with the laterality of usage. This Finnish study shows no evidence of any such correlation. In fact, if you take this Finnish study together with the existing studies out there, other than the studies by Dr. Lennart Hardell’s group in Sweden, studies that have serious limitations, in particular recall bias, the evidence supporting a link between cell phone radiation and cancer is so resoundingly nonexistent in epidemiology, preclinical science, and physics that it boggles the mind the WHO would come to even the tepid conclusion that cell phones should be added to Group 2B indicating that cell phone radiation might be carcinogenic. In reality, at worst, cell phone radiation might be reasonably placed in Group 3 (the agent is not classifiable as to its carcinogenicity to humans). More appropriately, it cell phone radiation should have been assigned to Group 4 (the agent is probably not carcinogenic to humans), almost based on physics alone.
Unfortunately, the WHO decision has the potential to do a great deal of damage. A couple of news stories demonstrate why. For example, the ever-woo-loving Tara Parker-Pope at the New York Times writes:
The W.H.O. panel ruled only that cellphones be classified as Category 2B, meaning they are possibly carcinogenic to humans, a designation the panel has given to 240 other agents, including the pesticide DDT, engine exhaust, lead and various industrial chemicals.
Look for the headlines on woo-friendly sites likening cell phones to pesticides and lead to appear soon, if they haven’t already.
Then there’s the credibility issue. As Sanjay Gupta put it:
Neurosurgeon and CNN chief medical correspondent Dr. Sanjay Gupta says Tuesday’s announcement, “dealt a blow to those who have long said, ‘There is no possible mechanism for cell phones to cause cancer.’ By classifying cell phones as a possible carcinogen, they also seem to be tacitly admitting a mechanism could exist.”
Well, not exactly. What they are doing, if anything, is demonstrating why scientific prior plausibility is so important. If it is so implausible that cell phone use can lead to cancer, based on physics alone, a measured reading would have concluded that, at worst cell phones are either Group 3 or Group 4, not Group 2B. As David A. Savitz, a professor in the departments of epidemiology and obstetrics and gynecology at Brown University and a researcher on environmental exposures and health, put it, “With few exceptions, the studies directly addressing the issue [cell phones as a brain cancer risk] indicate the lack of association.” Combining unconvincing epidemiological data with extreme scientific improbability from a basic science/physics standpoint should have equaled an assignment to “probably not carcinogenic in humans.”
I close, as I began, by pointing out that, unlike some physicists and skeptics, I don’t dismiss on basic science grounds alone the possibility of a link between cell phone radiation and cancer. In other words, I do not consider such a link to be impossible. I do, however, consider such a link to be incredibly implausible and improbable based on basic science considerations alone. Add to that the essentially negative epidemiological evidence, and, for now, I consider the question of whether or not there is a link between cell phone radiation and cancer to be in essence a dead issue, the question having been answered provisionally (and strongly) in the negative. My conclusion aside, my mind can still be changed by new evidence, of course. Indeed, to mention an example, I frequently tell even anti-vaccine activists that if they can produce convincing scientific data linking vaccines to autism I would seriously consider changing my mind. They have yet to do so, and I have yet to see convincing evidence of a link between cell phones and cancer. Certainly, this WHO report doesn’t even come close to what would be necessary to convince me to reconsider my conclusions regarding the existence of a link between cell phones and cancer. After all, it’s nothing new. There’s no new research presented, and the totality of the research that is presented is arguably misinterpreted. All this report does is to leave me profoundly puzzled as to why WHO would sully its scientific reputation by trumpeting such a dubious report.
Even so, in the spirit of keeping an open mind, I’ll keep an eye out for the full report and perhaps blog further about it after it’s released, either here or at my “more respectable” blogging home.