Cell Phone Radiation Alters Brain Metabolic Activity: National Institutes of Health (Volkow 2011)


Cell Phone Radiation Alters Brain Metabolic Activity

In 2011, a team led by Dr. Nora Volkow, head of the National Institute on Drug Abuse, used advanced imaging technology to monitor brain activity immediately following exposure to a cell phone. Conclusion: Weak cell phone emissions changed brain activity. The areas of the brain closest to the radiating antenna of a cell phone responded  with significantly increased glucose metabolism. The team published Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism in the prestigious Journal of the American Medical Association.

“Although speculative, one theory about how an artificial increase in brain glucose metabolism could be harmful is that it could potentially lead to the creation of molecules called free radicals, which in excess can damage healthy cells. Or it may be that repeated stimulation by electromagnetic radiation could set off an inflammatory response, which studies suggest is associated with a number of heath problems, including cancer.”The New York Times Coverage of Volkow's Study

Q: How was the study carried out?

A: Brain glucose metabolism was measured on two days, in 47 human male subjects. Participants rested for 50 minutes with phones strapped over each ear. After 20 minutes they were injected with a glucose-like tracer chemical, and after another 30 minutes their heads the phones were removed. Their heads were immediately scanned for levels of the tracer, that accumulates where glucose metabolism is greater. Unknown to participants and staff, on one day the cell phone on the right side was activated for 50 minutes (“on” condition), and the other day both cell phones were deactivated (“off” condition).

Q: What did the study find?  

A: In the region closest to the antenna, brain glucose metabolism was higher after the cell phone had been transmitting. As the published paper states, “In conclusion, this study provides evidence that in humans radiofrequency electromagnetic field exposure from cell phone use affects brain function, as shown by the regional increases in metabolic activity.”

Q: Why is this important?

A: Brain glucose metabolism is a marker of brain activity. Therefore, by measuring this endpoint, one can understand if the brain is sensitive to the exposure.

“The question that follows is – could repeated stimulation of these through these cell phone exposures say hours and a day after years, could they for example produce inflammatory responses that could be deleterious?” —Dr. Volkow, NIH Podcast
This study showed the brain did respond, which calls into question previous assumptions that the amount of radiation is “so low” that the body will not notice it. The authors clarify that “these results provide no information as to their relevance regarding potential carcinogenic effects (or lack of such effects) from chronic cell phone use.” The study was specifically about brain activity, and did not assess for impacts on health.

“We do have the obligation to evaluate whether there are long-term consequences from this exposure to electromagnetic radiation or not.” —Dr. Volkow to NPR’s Ira Flatow in NPR Interview
This research study raises important scientific questions:

  • Could increased glucose metabolism cause harm, or be related to harmful effects?
  • Could the brain be reacting in other ways which are unknown because we did not test for them?
  • What will the impact be from daily exposure?

Q: Did Dr. Volkow do the follow up studies she states that she wants to do?

A: No. As far as we know Dr. Volkow’s lab has not done any more research in this area. The study was funded by the US Department of Energy and the National Institutes of Health. We can only assume that no additional funding was provided for follow up research, and we question why follow up research was not done with such an important finding on a device so many people use every day. She states in her interviews that she would like to pursue more research and specifically speaks to how these results merit for further research. What happened?

The author affiliations were as follows: National Institute on Drug Abuse, Bethesda, Maryland (Dr Volkow); National Institute on Alcohol Abuse and Alcoholism, Bethesda (Drs. Volkow, Tomasi, and Telang and Mr. Wong); and Medical Department, Brookhaven National Laboratory, Upton, New York (Drs. Wang, Vaska, Fowler, and Logan and Mr. Alexoff).

Q: Do the researchers recommend that cell phone users take precautions?

A: Yes. Volkow is often quoted as recommending that people keep the phone away from their heads. Microwave News reports that Volkow stated, “Because we are uncertain of whether there are or are not long term consequences, my recommendation is to use a wired earpiece, use the cell phone in speaker phone mode or text message.” Volkow is the highest-ranking health official in the U.S. to call for caution in the use of cell phones.

Microwave News also reports that “The closing sentence of original version of the JAMA paper advised cell phone users to keep the antenna away from the brain by using a wired earpiece.” This was edited out in the review/revision process.

Q: Has any other research been done in this area since Volkow’s study?

A: Yes. In September 2013, Chinese researchers published “The Alteration of Spontaneous Low-Frequency Oscillations Caused by Acute EMF Exposure,” in Clinical Neurophysiology. The results demonstrated the RF-EMF exposure altered brain activity not only in the closer brain region but also in regions of the brain further from the antennae . The RF exposure was a 30-minute LTE signal (a higher frequency than Volkov’s) in this double-blind, crossover, randomized and counter-balanced study design. Read more in this press release on the research study: LTE Cell Phone Radiation Affects Brain Activity in Cell Phone Users.

A subsequent 2011 publication, GSM mobile phone radiation suppresses brain glucose metabolism, is sometimes erroneously referred to as demonstrating a lack of replication of Volkow at al.’s work. In a smaller sample of 13 subjects (versus Volkow et al.’s 27), Kwon et al. found that 33 minutes of exposure (versus Volkow’s 50 minutes) suppressed brain metabolism. As well, the study designs were different, in that Volkow et al. took measures to minimize baseline brain activity, keeping people quiet and checking that they didn’t fall asleep.  In  contrast, Kwon et al. continuously stimulated the brain during exposure, with a simple computerized task. Thus, Kwon’s study was not a replication study, and notably, also showed a significant effect. This study was funded by the Finnish National Technology Agency and is not a true replication study.

Q: What earlier research exists in this area?

A. In a 2002 publication, Peter Achermann’s group at the University of Zurich has shown similar changes in the brain from pulsed 900 mHz GSM cell phone-like emissions, but not from a continuous wave signal. In 16 subjects regional blood flow in the brain was increased following a 30-minute exposure, while a second group assessed by electroencephalogram (EEG) experienced greater alpha wave activity activity both before and during stage 2 sleep. With a sham or continuous wave exposure regional blood flow was unaffected. EEG was largely unchanged, although one higher frequency EEG spectrum “bin” was significantly decreased with pulsed, but not continuous wave or sham exposures.

Ackermann’s work garnered attention, and was replicated by others. A 2005 Australian study of 50 participants exposed for 30 minutes experienced brain activity changes with active mobile phone exposure compared with sham.  These include more rapid onset of rapid eye movement sleep, and increased EEG spectral power in the 11.5-12.25 Hz (alpha wave) frequency range during the initial period of sleep following exposure.

A 2007 UK study found that higher radiation exposures (in ‘talk’ mode) resulted in delayed sleep, in 10 subjects to ‘talk’, ‘listen’ and ‘standby’ modes during three sessions.

A 2011 Swedish study was larger and more detailed, with 48 participants exposed to a GSM signal or sham for 3 hours before a full night in a sleep laboratory. EEG alpha wave activity was again higher during lighter sleep (stage 2). Deeper sleep (stages 3 and 4) was delayed and shortened, indicating poorer quality sleep.

Non-confirmatory research results may be related to study parameters.

An Australian electrical and computer engineering group conducted a study of a dozen participants exposed to only 15 minutes of GSM-like radiation that did not penetrate the brain as deeply. They did not replicate the Achermann group’s work.

Acherman’s group more recently examined waking EEGs and cognitive testing of adolescents exposed to two levels of cell phone-like radiation and sham during three sessions. Importantly, cognitive testing was conducted during exposure. No significant differences were reported.

With publication of Volkov’s work, scientists released a joint statement on how it relates to past work, stating:

“These results are similar to our previous findings [Huber et al., 2002; Huber et al., 2005] where we used PET to show that RF EMF exposure induces changes in regional cerebral blood flow (rCBF) ipsilateral to exposure. Furthermore, although this study was the first to show an effect on brain metabolism, several previous studies have already demonstrated effects on brain activity (EEG during waking and sleep, cortical excitability).

Overall, these new findings support previous evidence that mobile phone RF EMF influences brain activity. Despite this, the underlying mechanisms or potential consequences of these alterations in brain function remain unknown. We believe that the dosimetry should be improved to further strengthen the study.”

—Sarah Loughran, Peter Achermann & Niels Kuster

Microwave News did an excellent summary of previous research in the Report: Connecting the Dots: Putting the Volkow Brain Scans in Perspective

After this research was published, the Journal of the American Medical Association published several comments by scientists.

“The majority of the radiofrequency energy emitted by a cellular telephone is absorbed by the hand and head of the user. The total energy absorbed is a function of the specific absorption rate, duration of use, and the manner in which the phone is used. In addition to concerns about potential harmful effects of such exposure, such as the issue of risk of brain cancer, change in brain function related to cell phone radio frequencies also is of concern. Studies have been conducted to investigate the effect of cell phone use on brain electrical activities, neurophysiology, and behavior. The study by Volkow and colleagues in this issue of JAMA  is the first investigation in humans of glucose metabolism in the brain after cell phone use.”

Read Comments by Henry Lai, PhD; Lennart Hardell, MD, PhD

In addition to the Lai and Hardell letter quoted above, three letters were critical of the study, focusing largely on detailed estimation of radiation absorption in the brain. Volkow replied in JAMA that their simple model was justified, consistent with the findings, and in any case such details would not impinge on the significance of the observed enhanced metabolism. Notably, some of the critics have industrial ties. Quirino Balzano is a former senior executive at Motorola, while Christopher Davis was an expert witness for the defense in the Newman brain tumor lawsuit.


Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism

NIH Podcast and Transcript:Dr. Nora Volkow discusses JAMA paper, “Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism”

Brookhaven Press Release: Summary of Intramural NIH/ Brookhaven National Laboratory Cell Phone Study in JAMA

NPR’s Ira Flatow Interviews Nora Volkow on How Cell Phone Radiation Affects Brain

CNN: Cell phone exposure increases brain cell activity

New York Times: Cellphone Use Tied to Changes in Brain Activity

PBS Health Study: Cell Phone Radiation Stirs Brain Activity, but Health Effects Unknown

Microwave News: Cell Phone Radiation Changes Brain Metabolism

Environmental News Service Press Release


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