Cell Phone, Brain Metabolism Study Revisited
March 3, 2011
Last week I reported on research showing Cell Phones Affect Brain Metabolism. While the report found a link between cell phones and glucose metabolism in the brain, it also said the findings were of "unknown clinical significance." Based on the analysis by a knowledge reader who reviewed the finding, they may actually be of no clinical significance. First, the study notes that the normal variation in glucose metabolism for sedentary activities such as looking at picture ranges from 6 percent to 60 percent. If an increase of 5 percent or so (the increase measured near the cell phone earpiece) is a health risk, it would seem looking at pictures or other sedentary activity poses a far greater danger.
The reader notes a bigger issue with the study is that its conclusion that the intensity of exposure correlates with glucose uptake is based on the assumption that the cell phone's antenna is at the earpiece. While that's often the case, the reader noted that the antenna of the phone used in the study happens to be near the mouthpiece. The reader's conclusion is the exposure estimate, and, by extension, the correlation calculations, therefore cannot be correct.
While the brain metabolism study received wide press coverage, I saw few media reports on a very extensive study by researchers at the University of Manchester showing Mobile phone use is not related to increased brain cancer risk. That study used publicly available data from the U.K. Office of National Statistics to look at trends in rates of newly diagnosed brain cancers in England between 1998 and 2007. Lead researcher Dr. Frank de Vocht, an expert in occupational and environmental health in the University of Manchester's School of Community-Based Medicine, said, "There is an on-going controversy about whether radio frequency exposure from mobile phones increases the risk of brain cancer. Our findings indicate that a causal link between mobile phone use and cancer is unlikely because there is no evidence of any significant increase in the disease since their introduction and rapid proliferation"
The University of Manchester news release noted that due to the fact that there is "no plausible biological mechanism for radio waves to damage our genes directly," radio frequency exposure--if related to cancer--is more likely to promote growth in existing brain tumors.
If that were the case, they would have expected to find an increase in the number of diagnosed cases within five to 10 years after the introduction of mobile phones and also for the trend to continue as mobile phone use became more widespread.
The study did find a small increase in the rate of brain tumors during the period.
Dr. de Vocht explained, "It is very unlikely that we are at the forefront of a brain cancer epidemic related to mobile phones, as some have suggested, although we did observe a small increased rate of brain cancers in the temporal lobe corresponding to the time period when mobile phone use rose from zero to 65 percent of households."
He said that to put this into perspective, "if this specific rise in tumor incidence was caused by mobile phone use, it would contribute to less than one additional case per 100,000 population in a decade."
He noted that while the possibility of some people being susceptible to radio-frequency exposure exists, or that there was the possibility that some rare brain cancers could be associated with RF, the data should be interpreted "as not indicating a pressing need to implement public health measures to reduce radio-frequency exposure from mobile phones."