In the past 6 months, Skeptic North has run several articles about WiFi, cell phones and the purported health effects that radio-frequency electro-magnetic fields (RF-EMF) may or may not have on the brain and body. Despite the overwhelming evidence to the contrary, the controversy remains to be a popular story in the media, perhaps because of the ubiquitous nature of cellular technology and the popular meme of the hidden dangers of modern life. I and others have continued to insist that there is no good evidence of any effect by the microwave radiation emitted by cell phones, cell towers and other electronics on the brain and other body systems, let alone that this radiation causes cancer or other serious illnesses. The syndrome referred to as electro-hypersensitivity remains un-proved and unfounded, but it seems like there is new evidence that shows that the normal levels of radiation emitted by a cell phone can effect neuronal cells in the brain.
All over the news this week were reports of a new study purporting to show a link between cell phone EMF radiation and increased brain metabolism. The study was conducted by a well-respected group of NIH researchers conducting tests at the Brookhaven National Laboratory in the US. The study is available in abstract for free here, but you have to pay to have access to the full text version. Reporters all over network news told a simplified story of the paper by Volkow et al, published in the Journal of the American Medical Association, and drew conclusions outside the scope of the study, inflaming an already overly effulgent debate.
PET is a pretty cool technology. A radioactive tracing molecule is attached to an active organic substance, like a neurotransmitter, or glucose, the energy source for the cell, and the PET scanner records the emissions of the radio-tracer and maps their position in 3 dimensions. This way, you can see exactly where, at the cellular level, the tagged molecule has been taken up or is acting. In the case of this study, the radio-tracer used was fluorine-18 and it was attached to glucose, so it is possible to locate the concentration gradients of glucose in the brain.
The objective of Volkow’s study was to “evaluate if acute cell phone exposure affects brain glucose metabolism, a marker of brain activity.” That is it. Two cellphones were attached to the head, one on each side of the normal listening position, and two randomized groups of subjects were exposed either to one of the cell phones (always the right one) receiving a muted call lasting 50 minutes or two cell phones that were off. The radio-tracer was injected at the 20 min mark of the phone call, which was muted so the subject could not pick up any audio clues from the call, and 30 minutes later, the phone apparatus was taken off and a PET scan was done to look at glucose metabolism in the brain while the subject was at rest.
The authors report a 7 % increase in glucose metabolism in areas closest to the antenna of the phone, though with a wide confidence interval this could have been as low as 2 % and as high as 12 %. I am not an expert, and I have to rely on the opinion of those who know the literature, but I am assured by CASS advisors who’s specialty is neurology that the paper is in line with what we already know about the effects of EMF on the brain, and Volkow makes this point in the paper as well. The researchers are pretty sure that the effects were not due to thermal heating but they cannot identify a mechanism as of yet as to why the increase was recorded. The authors summarize their conclusions as follows:
“In summary, this study provides evidence that in humans RF-EMF exposure from cell phone use affects brain function, as shown by the regional increases in metabolic activity. It also documents that the observed effects were greatest in brain regions that had the highest amplitude of RF-EMF emissions (for the specific cell phones used in this study and their position relative to the head when in use), which suggests that the metabolic increases are secondary to the absorption of RF-EMF energy emitted by the cell phone. Further studies are needed to assess if these effects could have potential long-term harmful consequences.”
The participants were blinded, with subjects not knowing which phones were on, and there was a wash-out period and a re-analysis conducted on each subject, with all subjects randomized as to which exposure, real or sham, they would experience first. The researchers were not blinded and this may have been a source of bias, and the phones could have had a heating effect due to operation that was impossible to blind for (think of how hot your cell phone gets after a 20-minute call, or so), but the statistical analysis was appropriate and can be trusted. One small criticism of the method could be that they should have had a random distribution of the left or right cell phone when it was on, but the methods were very solid and the study is well designed and analyzed.
An important caveat is that this study falls into the category of studies that look for changes in chemical markers instead of clinical effects. The authors did not investigate if there were any physical sign of changes in cognition or brain activity, only the uptake of glucose, an established marker for the level of metabolism in the brain due to the heavy reliance of the brain on glucose for its functioning. All the scans were right after the exposure, and there is no evidence that even medium term changes in function occur, as is evidenced by the normal activity in the placebo arm after the mean washout period of 5 days. The authors make it very clear in the conclusion that this study does not show any indication of long term changes in the structure or function of the brain nor any change in risk of cancer:
“Results of this study provide evidence that acute cell phone exposure affects brain metabolic activity. However, these results provide no information as to their relevance regarding potential carcinogenic effects (or lack of such effects) from chronic cell phone use.”
In the past I have thought that the low levels of EMF radiated by cell phones had no effect on neuronal tissue. This study shows that it does, and assuming that the methods were sound and that the study can be replicated, I have changed my mind. That is how science works. This is the type of evidence that is required to advance a field of study, and nowhere have skeptics called for an abandonment of the study of the effects of radio-frequency EMF on humans. We have only ever called for rigorous, well designed studies that make appropriate attempts to eliminate bias from the investigation and present their results in an honest and open way that does not draw conclusions outside the scope of the analysis conducted.
Of course the media love conflict and have risen to the challenge, with reporters brandishing their wired ear pieces and suggesting that it is better safe than sorry and not put the cell phone to your ear. There is nothing wrong with this thinking, as long as the next conclusion is not ‘because cell phones are a risk for brain cancer’ as was suggested by The Sun in the UK (it is obvious they did not even read the study, as they say that 1000′s of participants were involved, when in fact there were only 47!).
This study is what it is: another thread in the fine woven cloth of our knowledge of nature. It is not a panacea, nor does it refute any evidence that there is or is not a risk of health effects from cell phone use, nor does it show a mechanism of how EMF could alter biological systems. Anybody who purports that it does is basing this conclusion on ideology, not science.