Excerpted below are the sections of this review paper by Nazıroğlu and Akman (2014) that address blood-brain barrier penetration. Blood-brain barrier penetration after exposure to low intensity (as opposed to greater intensity) microwave radiation has been observed in various studies since it was first reported by Allan Frey in 1975.
Cell Phone & Wi-Fi EMR Effects on Oxidative Stress & Molecular Pathways in the Brain
This phenomenon is problematic for the development of safe RF regulatory standards as well as for the development of harm reduction recommendations via personal behavior change. I would be interested in learning what other people think about this line of research, especially its policy implications.
Effects of Cellular Phone- and Wi-Fi-Induced Electromagnetic Radiation on Oxidative Stress and Molecular Pathways in Brain
Mustafa Nazıroğlu, Hatice Akman. Effects of Cellular Phone- and Wi-Fi-Induced Electromagnetic Radiation on Oxidative Stress and Molecular Pathways in Brain.
Systems Biology of Free Radicals and Antioxidants. 2014, pp 2431-244.
Several studies have suggested that EMR emitted by wireless devices can interfere with learning and memory in both animal models and human, but the results obtained are controversial and the molecular basis of this interaction is still unclear. Electromagnetic radiation may induce some degenerative effects in the brain by increasing oxidative stress and DNA breakage plus interference with the blood–brain barrier permeability. There are also recent reports on the role of Wi-Fi and mobile phone frequencies on Ca2+ influx through Ca2+ channels. The EMR increases ROS production in the neurons through the activation of oxidant system including NADPH oxidase activity and nitric oxide production. These effects are accompanied by a decrease in brain tissue of enzymatic antioxidants such as superoxide dismutase, catalase, and glutathione peroxidase together with a fall in the levels of nonenzymatic antioxidants such as glutathione and vitamin C.
Cell phone- and Wi-Fi-induced EMR appears to induce degenerative effects through increase of oxidative stress and decrease of antioxidants in the brain that affect neuronal physiological functions. Antioxidants seem to counteract the effects on the EMR, however.
Safe Doses of Wi-Fi in Brain
There are also ongoing dosimetry studies that measure RF levels around the globe, including that coming from various sources including wireless local area networks (WLANs) which indicate that the associated exposure level is low (Foster and Glaser 2007). Martínez‐Búrdalo and Martin (2009) reported that measuring local energy SAR rates in different areas of the brain in a rat exposed to RF rate revealed that two brain regions that are spaced less than a millimeter apart can have more than a twofold difference in SAR. Martens et al. (1995) also reported that the peak (hot spot) for SAR in the head tissue of a user of a mobile telephone can range from 2–8 W/kg2 per watt output of the device. The peak energy output of mobile telephones can range from 0.6–1 W, although the average output is closer to 0.6 than to 1.0 Studies have shown that neurological damage can be observed at exposure levels of 0.12 mW/kg (Eberhardt et al. 2008). This is less than one eighth of the average exposure level of 1 mW/kg found 150–200 m from a mobile phone mast. The researchers concluded that “the weakest fields are the biologically most harmful.”
Yioultsis et al. (2002) studied the occurrence of considerable differences in electric field or SAR values. They also demonstrated high radiation absorption by the head, which, apart from any possible biological damage, caused a rise in brain temperature after a 10-min exposure. Although both SAR values and the thermal rise in the case of a WLAN are one or two orders of magnitude lower than before exposure, the issue of prolonged exposure is raised, since it is found that the safety limits for long exposure are also marginally violated.
The exposure system they developed allows experiments to be performed for the evaluation of biological effects of electromagnetic field exposure during early life. They found that average whole-body SAR drastically changes during the exposure period according to the size and weight of the new born mice.
Blood – brain barrier permeability
Salford et al. (1997) exposed rats to microwave radiation at an intensity equivalent to that received by a mobile phone user. They investigated the ease by which substances toxic to the central nervous system can cross over from the blood into the brain and found that the blood–brain barrier breaks down after a 2-min exposure. They demonstrated consequent neural damage especially in subjects of middle age and deduced that mobile phone use can precipitate degenerative brain effects. In addition, Nittby et al. (2008) and Nittby et al. (2009) and Salford (2007) have found that very low emission energy levels cause more leakage across the blood–brain barrier than higher levels.
Franke et al. (2005) reported that no changes in the blood–brain barrier permeability to sucrose occurred in response to constant exposure, over a period of 1–5 days, to a mobile phone signal at 1,800 MHz. Grafstrom et al. (2008) similarly could find no change in the permeability of the blood–brain barrier to several types of markers and observed no dark neurons or neuronal damage after exposing rats to a mobile phone 900 signal with an SAR of 0.6 or 60 mW/kg for 2 h per week, over a period of 55 weeks. Masuda et al. (2009) observed the passage of plasma protein albumin across the blood–brain barrier and no appearance of dark neurons in experiments. McQuade et al. (2009) observed no effect of a 30-min exposure to modulated GSM 915 MHz (two types of modulation: 217 Hz and 16 Hz) or to a continuous signal (SAR of 0.0018–20 W/kg in male rats). Poulletier De Gannes et al. (2009) also detected no effect on blood–brain barrier integrity or neuronal degeneration. These authors also assessed neuronal apoptosis. Cosquer et al. (2005) observed no effect of semi-chronic exposure to 2.45 GHz pulses (2 μs, 500 Hz) for 45 min per day over 10 days, using neither indirect observations based on cognitive tests nor by the passage of Evans blue dye across the blood–brain barrier (study carried out on 36 male rats). For the cognitive tests, the authors investigated whether radio frequency modified the behavioral response of the animals to the injection of a muscarinic antagonist (scopolamine) that crosses the blood–brain barrier only poorly. The response of the cage control rats differed from those seen in the sham-exposed and exposed rats (effect of stress), despite habituation to handling before testing.
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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