Rhinocrisy

A few weeks back I happened across a news story trumpeting a link between cell phones and brain tumors, containing the ominous warning that cell phones are “worse than cigarettes”. By coincidence my roommate had happened to ask me if I knew anything about the subject, and so I spent a portion of the previous day scouring PubMed to answer this very question, and had, of course, also compared against cigarettes as the outstanding example of a public-health disaster caused by personal foibles.

So my immediate reaction to the story (”Balls.”) was based on more than just a gut feeling.

But let’s start off by poisoning the well a little bit: the source for this story was an Australian neurosurgeon named Vini Khurana. Vini’s methodology in answering this question was exactly the same as mine: reading some papers on PubMed. We should be clear that reviews are an important part of scientific literature, and they are a great way to collect information and present a perspective on the field. They’re usually the product of specific solicitations by journal editors to respected members of a field - e.g., asking James Hansen to write a review on the global temperature record, or even asking someone like Carl Woese to write a review on the future directions for the entire field of biology. The idea is that someone with a demonstrated expertise in the field is surely best-positioned to report on its history and state-of-the-art.

But no one solicited Vini’s article. In fact, Vini has no history of publication in the field. In fact, Vini didn’t even publish this paper anywhere. It was published on the web and was completely unreviewed.^*

As I’ve suggested before, I think the manner of propagation of many news stories is purely viral: something happens to make it onto some wire service, and if it is interesting or sensational, it spreads. As its exposure increases, so do opportunities for further dissemination - another outlet picks it up, and the cycle continues. This process doesn’t seem to include anything like quality control or actual journalism (mayhap the journalists here can speak to why this might be the case), with the result that bad, bad science gets broadcast loudly around the globe.

At any rate, the question at hand remains to be answered: do cell phones cause brain tumors? After Vini’s own pathetic review, he recommends an actual review in the Journal of Radiation Biology, whose abstract tells us:

Biophysical considerations indicate that there is little theoretical basis for anticipating that RF energy would have significant biological effects at the power levels used by modern mobile phones and their base station antennas. The epidemiological evidence for a causal association between cancer and RF energy is weak and limited. Animal studies have provided no consistent evidence that exposure to RF energy at non-thermal intensities causes or promotes cancer. Extensive in vitro studies have found no consistent evidence of genotoxic potential, but in vitro studies assessing the epigenetic potential of RF energy are limited. Overall, a weight-of-evidence evaluation shows that the current evidence for a causal association between cancer and exposure to RF energy is weak and unconvincing.

That first sentence, by the way, is an important one: there’s little justification for the notion of non-ionizing radiation being a significant cause of DNA damage.

Meanwhile, a simple comparison of some epidemiological studies on the question is revealing. This study finds odds ratios of 1.22 and 0.70 for gliomas and menigiomas respectively. This one finds an odds ratio of 0.6 for gliomas, with a 95% confidence interval of 0.4-0.9. I.e., the study finds that regular cell phone use is slightly protective against gliomas! And finally, this study examines both long- and short-term users of cell phones and finds no increased odds of acquiring tumors through phone use in either group.

By now you are probably shivering in your boots^†, so let’s take you back down a little, with a sentence from this case-control study:

The odds ratio (OR) for lung cancer in current United States smokers relative to nonsmokers was 40.4.

The short version: As you were, lieutenant.

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^* Yes, reviews are normally reviewed. The reviewers of reviews are called re-reviewers, and they are required to do their reviewing work between two facing mirrors to deepen their powers of meta-analysis.

^† You are wearing your boots, right?

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Posted on Friday, April 11th, 2008 at 3:34 pm | Biology, Science!, We're Doomed! | feed | reply | trackback