Which poses a greater risk - the cell phone or the lack of a helmet?

Which poses a greater risk – the cell phone or the lack of a helmet?

Recently there was another round of scaremongering headlines and articles claiming that cell phones can cause brain cancer. The Daily News wrote: “The scientists were right — your cell phone can give you cancer.” Many online news sites declared: “SHOCK STUDY: CELLPHONES CAN CAUSE CANCER,” in all caps to make sure you understand that you should be alarmed. None of the mainstream reporting I saw looked past the press release.

The study

Let’s take a look at the actual study: “Oxidative mechanisms of biological activity of low-intensity radiofrequency radiation” published in Electromagnetic Biology and Medicine.

The first thing to note as that this is a review article. It does not present any new data. It is not an experiment or observational study. It’s not even a meta-analysis. It is just a group of researchers looking at the literature and proclaiming that it confirms what they already believed.

Review articles serve a legitimate purpose in science. They are a primary way that researchers communicate with each other and express their opinion. But they should not be presented as if they are new data, or as if they confirm one side in a debate. They can be abused, however, in a process called citation bias – packing the review with citations that support your side to make it seem like it is more robust than it actually is (a process which can even start inadvertently just by relying reference lists rather than databases).

The lead author of the current review (to avoid confusion it really shouldn’t be called a “study”), Igor Yakymenko, has published several articles arguing that low intensity radio-frequency radiation (RFR) can increase oxidative stress in tissues and this is a possible mechanism of increased disease risk. In his current review he argues that the published evidence supports this position.

While the evidence may support the notion that RFR can increase markers of oxidative activity in tissue, it does not establish that this increase is biologically important and can actually lead to specific diseases. It also does not establish that cell phone use causes any harm by this mechanism.

At this point Yakymenko’s hypothesis is still speculative, and there is no evidence to make claims for actual health effects. There is no problem with him publishing a review of the data and arguing for his hypothesis, but it is dubious behavior to send out a sensational press release declaring victory in a scientific debate because of your own review, and then linking your claims to scary health concerns.

As we have argued here many times on SBM, basic science studies looking at complex biological markers in vitro or in animal studies are very difficult to extrapolate to net health effects in humans. It is tempting, however, for researchers to speculate wildly from biochemical changes measured in cells to downstream health effects. This applies equally to claims for health benefits as to claims for health risks.

Cell phones and cancer

I have written several times over the years about the scientific literature examining a possible link between cell phone use and cancer risk. At present there is no convincing evidence for a link, but the possibility of a link is not without controversy.

A 2012 systematic review of the literature looking at a possible connection concluded:

Meta-analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head.

However, a 2013 study looking at the CERENAT case-control data, found an increased risk of gliomas and meningiomas in the heaviest users. They found no association between cell phones and cancer as a whole, only in these subgroups.

Further there is some suggestion that the side of cell phone use correlates with the side of the tumor, but in this data this association was generally not statistically significant.

A 2014 study looking at cell phones, cordless phones, and acoustic neuroma concluded:

The findings do not support the hypothesis that long-term mobile phone use increases the risk of acoustic neuroma. The study suggests that phone use might increase the likelihood that an acoustic neuroma case is detected and that there could be bias in the laterality analyses performed in previous studies.

It also needs to be noted that there is a pretty solid consensus at this point among scientists that there is no convincing evidence for a link between cell phone use and cancers. There is a notable outlier, however, Swedish researcher Lennart Hardell. David Gorski wrote the definitive assessment of Hardell:

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.

Perhaps the most reassuring data is that brain tumors overall have not been increasing overall in the last 30 years. The data shows a slight increase in the 1970s and early 1980s, which was almost certainly due to the introduction of CT scans and then MRI scans allowing for more accurate diagnosis.

Trends in brain cancer

Since 1990, when cell phones started to be used, brain tumor incidence has been flat, possibly even declining slightly. This trend continues to the present day. We therefore have about 25 years of data showing that a dramatic increase in cell phone use over that time has not resulted in an increase in brain tumors overall. This is a powerful argument against any causal connection between cell phone use and brain tumors.

Of course, there are those, like the author of the current review, who argue that we need still more time. Perhaps it takes 30 years for the effect to manifest.

This is always the issue we run into with scientific data regarding possible risks – the data is always limited. We can never prove zero risk. Absence of data showing a connection can also be dismissed with arguments that the dose was not high enough, exposure was not long enough, or we did not look at the correct sub-groups. You can make these arguments about any absence of risk in the scientific data.

While we can’t prove zero risk, at some point the probable remaining risk becomes too small to worry about. At some point you are more likely to die because you did not have access to a cell phone, than from the radiation from cell phone use.

Conclusion – The failure of the media

This latest review was gleefully met by the mainstream media with utter credulity, which allowed them to post sensational click-bait headlines scaring the public yet again about cell phones and cancer. Few bothered to put this review into a proper context.

Interestingly, a recent survey finds that most people focus on the wrong risks for cancer. While awareness of tobacco and sun exposure is very high, many people focus on dubious risks, such as GMOs and pesticides, while failing to note proven risks, such as lack of exercise and eating too few fruits and vegetables.

Even more interesting, cell phone use did not even make the list. Other surveys find that even when consumers hear about a possible link between cell phones and cancer, they state they will not change their behavior.

It seems that in this one case, our addiction to the convenience of cell phones trumps dubious fear.

 

 

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the president and co-founder of the New England Skeptical Society, the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also contributes every Sunday to The Rogues Gallery, the official blog of the SGU.

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