Jul 28 2008

More on Cell Phones and Brain Cancer

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Comments: 17

Last year I wrote an entry summarizing the evidence concerning the association of cell phone use and brain tumors. The bottom line of my discussion was that the plausibility of the claim that cell phones may cause brain tumors was low but not very low; there is currently no reliable evidence for a correlation but neither has one been definitively ruled out, for cell phone use of less than 10 years the data is basically negative, and for cell phone use greater than 10 years there is also no definitive evidence for a correlation with brain tumors but the data has a slightly positive trend, ruling out any clear or strong effect but not a small effect. There is a theoretical concern that if there is a small effect the children may be more susceptible.

I have also discussed this data in a Youtube video, and recently Orac has summarized the evidence as well.

Fears of cell phone use and cancer have resurfaced in the public consciousness due to a memorandum written by Dr. Ronald Herberman, The director of the University of Pittsburgh Cancer Institute and UPMC Cancer Centers. He issued an advisory to the 3000 faculty and staff of his institution stating:

“Recently I have become aware of the growing body of literature linking long-term cell phone use to possible adverse health effects including cancer. Although the evidence is still controversial, I am convinced that there are sufficient data to warrant issuing an advisory to share some precautionary advice on cell phone use.”

He also cites preliminary and unpublished data to support his concerns. I do not want to discuss again the data itself, and will simply refer back to my previous blog post as well as Orac’s for a summary of the existing research on this question. I do want to discuss the appropriateness of Dr. Herberman’s actions – or the balancing act of giving fair and early warning about potential risks or threats without becoming an alarmist or causing more harm than good.

Herberman defended his actions, saying:

“Really at the heart of my concern is that we shouldn’t wait for a definitive study to come out, but err on the side of being safe rather than sorry later.”

He also added that science is slow and we cannot always afford to wait for it. I think this is one of several legitimate points that need to be considered in assessing future or potential harm. It is reasonable to consider the possible or plausible risks that new technologies or behaviors may pose. In some cases, certainly, it should be policy to adequately demonstrate safety first- prior to market. Drugs and medical devices, for example, should provide a reasonable amount of data on safety before going to market. The same should be true for herbs and supplements, in my opinion. Cars also need to pass safety testing before going to market. This is a good thing.

It is simply not possible, however, to rule out every small risk. Life comes with risk, and data will never be perfect. Also, small risks that require millions of people to be exposed or years of exposure cannot be studied until after a product is on the market and is actually being used by millions of people. Cell phones fall into this category.

Similar arguments come into play for topics like global warming. While there appears to be a solid consensus that global warming is happening, and the international panel on climate change estimated that there is a 90% probability it is significantly man-made, there is uncertainty as to pace, extent, and final consequences of global climate change. Some argue that given the uncertainties we should essentially not worry about it and definitely not make economically harmful moves to prevent it. Others argue that by the time we know for sure the causes, extent, and consequences of global warming it will be too late – so we should at least start working on the problem now. Global warming skeptics paint believers as hysterical alarmists, while those warning about warming regard the skeptics as deniers.

To be clear, I am not comparing the cell phone-cancer evidence with global warming, only stating that the same issues exist regarding balancing the need for early warning without needlessly alarming people. In text of Herberman’s warning makes a comparison to asbestos, but I think that is a false analogy (as it is with tobacco, a comparison others have used). Asbestos and tobacco are known disease-causing agents. The data was actually quite clear about the risks of these products long before regulation addressed them.

Another potential analogy is with concerns that silicone breast implants cause autoimmune disease, a claim that literally bankrupted Dow chemicals. The early data was negative and the later definitive data was negative. Concerns were largely driven by anecdotes. In the end the claim that silicone breast implants cause autoimmune disease was nothing more than an urban legend. But this is not a good analogy to cell phones either because the evidence for cell phones is at least somewhat ambiguous and not based solely on anecdotes.


There are many cautionary tales that one can draw upon to support almost any stance toward cell phones and cancer. If we wait for definitive evidence then meanwhile people will be needlessly harmed. If we over react to preliminary evidence then we may needlessly worry and inconvenience people and even bankrupt companies. I think that in general the FDA and other agencies have struck a reasonable balance. Their position has been that the data is mostly negative but not definitive. Therefore, “if” you are concerned that take the following steps to limit risk – such as use a hands free device and limit cell phone use. They give information and some practical advice without alarming people.

I think that Herberman did not strike an optimal balance, erring too much on the side of caution and drawing some poor analogies. I also disagree with citing unpublished preliminary evidence – if the evidence was concerning then early publication would be justified. But he does have a point that it is reasonable to thoughtfully consider potential risk and sometimes we have to make decisions in the absence of final data. Being cautious is neither always right or always wrong – individual decisions have to be made in each case. Also, individual people may reasonably make different decision for themselves. We don’t all desire the same balance of risk and convenience (or risk and fun – snowboarding and hang gliding being good examples).

In ambiguous cases the best thing to do is just provide the information to the public and let them decide what risk is acceptable to them.

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