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WHO Says Cell Phones May Not Cause Cancer

1 June 2011. The headline I used above might have graced your monrning newspaper or news website were it not for the fact that too many people would recognize that it says nothing important. The claim that cell phones may not cause cancer, however, is just as true as the claim that they may cause cancer, which also says nothing important but implies otherwise. The only headline that could be less informative would be WHO Says Cell Phones May or May Not Cause Cancer.

We can't blame the news media for playing up this story, but we can blame ourselves if we don't dig a little deeper and try to undertand what it means.

The WHO report is not based on any new data. The report was written by WHO's International Agency for Research on Cancer (IARC), which consists of 31 scientists from 14 countries. There is no way I am going to investigate these 31 scientists to try to discover their motivation. They must have known their report would frighten many people and fuel the fires of zealots like the followers of Paul Brodeur, George Carlo, Devra Davis, and Lloyd Morgan. (I discuss Davis here and the others here.) Perhaps their intuition tells them that cell phones cause brain cancer. Maybe they just know this in their hearts. The evidence doesn't support this intuition, but you can always make a possible causal connection look plausible if you present only or give undue weight to a small slice of all the evidence available. That is what the WHO did.

"After reviewing essentially all the evidence that is relevant ... the working group classified radiofrequency electromagnetic fields as possibly carcinogenic to humans," Jonathan Samet, chair of the IARC group, said in a telebriefing. He said some evidence suggested a link between an increased risk for glioma, a type of brain cancer, and mobile phone use.*

The WHO panel justified classifying cell phones as a possible carcinogen by selecting one bit of one study from among dozens of studies that were part of the Interphone study. That one study was published last September in the International Journal of Epidemiology. The conclusion of the scientists who published the study was:

Overall, no increase in risk of glioma [malignant brain tumor] or meningioma [benign brain tumor] was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation." [emphasis added]

Scientific studies are not all of equal value or significance. Studies vary in quality, in the number of data points, and in duration. Some study a few people for a short time. Even the best designed and executed of such studies can't be any more than suggestive. Epidemiological studies, by their very nature, cannot establish a positive causal link, but they can indicate a high probability of there not being a causal link if no correlation is found between two studied phenomena. For any complex issue, there are likely to be some studies that go against the grain, whose authors conclude something contrary to the vast majority of the other studies. There must be a compelling reason for giving the outliers equal status with the majority. In the case of an increased risk of glioma by the group with the highest cell phone usage, an outlier was promoted to the major leagues by the WHO without providing any compelling reason for doing so.

Finally, before allowing the WHO study to scare you, consider this: the majority of physicists argue that radiofrequency electomagnetic fields are about 1,000,000 times too weak to cause mutations in genetic material, a necessary condition for cancer. Epidemiologists, public health workers, physicians, and others without much background in physics are usually the ones claiming EMFs cause cancer. Their evidence is almost always a reference to a correlation found in some epidemiological study. Focusing on the studies that support a belief in danger from EMFs and ignoring the conclusions of the vast majority of researchers, has given birth to many Jeremiahs. Many sincerely appeal to the precautionary principle as justifying their raising the fear flag. I don't doubt their sincerity, but I don't think their calls for alarm are justified.

postscript: Please, don't drive while texting. It can be deadly. Also, driving while using a handsfree cell phone is as dangerous as driving while drunk, according to a scientific study (so, it must be true, right?).

further reading

Why I’m (still) not worried about my cell phone hurting my brain by Phil Plait

The bride of the son of the revenge of cell phones and cancer rises from the grave...again by Orac

Cell phones, brain cancer, and other cheery thoughts by R. T. Carroll

Warning: Your Magazine May Be Hazardous to Your Health by R. T. Carroll

The Disconnect in Disconnect by R. T. Carroll

The Skeptic's Dictionary entries on electromagnetic radiation and electrosensitives