Effects of GSM 900 MHz on Middle Cerebral Artery Blood Flow Assessed by Transcranial Doppler Sonography

Abstract

Mobile phone use has increased worldwide but its possible effects on the brain remain unclear. The aim of the present study was to investigate the effect of acute exposure to a radio frequency electromagnetic field (RF EMF) generated by a mobile phone operating in the Global System for Mobile Communication (GSM) 900 MHz on cerebral blood flow. Twenty-nine volunteers attended two experimental sessions: a sham exposure session and a real exposure session in a cross-over double-blind study in which a mobile phone was positioned on the left side of the head. In one session, the mobile phone was operated without RF radiation (sham phone) and in the other study it was operated with RF radiation (real phone) for 20 min. Thus, each subject served as its own control. Middle cerebral artery blood flow was monitored noninvasively by transcranial Doppler sonography to measure middle cerebral artery blood flow velocity. Pulsatility index and resistance index were also evaluated. A voluntary breath holding physiological test was carried out as a positive control for testing cerebral vasoreactivity. Hemodynamic variables were recorded and analyzed before, during and after mobile phone exposure. No significant changes were detected in studied variables in middle cerebral arteries during sham or real exposure. In the exposed side the cerebral blood flow velocity, the pulsatility index and the resistance index during sham and real exposure were respectively: [61.9 ± 1.3, 61.7 ± 1.3 cm/s (P = 0.89)]; [0.93 ± 0.03, 0.90 ± 0.02 (P = 0.84)] and [0.58 ± 0.01, 0.58 ± 0.01 (P = 0.96)] at baseline; and [60.6 ± 1.3, 62 ± 1.6 cm/s (P = 0.40)]; [0.91 ± 0.03, 0.87 ± 0.03 (P = 0.97)]; [0.57 ± 0.01, 0.56 ± 0.01 (P = 0.82)] after 20 min of exposure. Twenty minutes of RF exposure to a mobile phone does not seem to affect the cerebral circulation.

Is the Effect of Mobile Phone Radiofrequency Waves on Human Skin Perfusion Non‐Thermal?

“…Hence, it is unlikely that cutaneous heating induced by a mobile phone can trigger significant hemodynamic changes in cerebral vessels via the conductive heating of blood per se. An echo Doppler study performed under the same experimental conditions and with the same radiofrequency exposure did not show any significant change in flow from the brain arteries [15]. These observations show that the brain's hemodynamics was not perturbed by local skin heating.…”

Radiofrequency signal affects alpha band in resting electroencephalogram

“…The maximum specific absorption rates (SARs) were averaged on 10 g tissue, 1 g tissue, and the peak value was measured at 0.49 W/kg, 0.70 W/kg, and 0.93 W/kg, respectively. The SAR of the sham phone was below the detection level of the system (0.001 W/kg) at any position of the phantom, and no electric field was detected on the surface of the sham phone (for more details, see Ghosn et al 2012 EEG recording and data acquisition. Electroencephalography data were recorded using BrainCap (EASYCAP Products, Herrsching, Germany) with 29 passive electrodes (Fp1 , Fp2, F7, F3, Fz, F4, F8, FC5, FC1, FC2, FC6, T7, C3, Cz, C4, T8, CP5, CP1, CP2, CP6, P7, P3, Pz, P4, P8, PO3, PO4, O1, and O2) placed according to the international extended 10/10 system.…”

“…Among these parameters are electrode impedance changes. The battery and electronics of the phone causes it to heat up, which, in turn, causes heating of the skin and underlying tissue (Anderson and Rowley 2007;Ghosn et al 2012, Straume et al 2005. As exposure to heat causes the dilation of blood vessels, this phenomenon may result in a change in the skin impedance (Luck 2005), which, in turn, could explain some observed changes in the recorded EEG power.…”

Evaluation of Inflammation by Cytokine Production Following Combined Exposure to Ultraviolet and Radiofrequency Radiation of Mobile Phones on 3D Reconstructed Human Skin In Vitro

“…It is also important to note that mobile wireless systems produce additional conductive thermal exposure on the skin along with RF absorption [14][15][16]. For example, increase of skin temperature due to 20 min exposure to RF of mobile phones was reported by Ghosn et al [17]. Studies on the effect of RF-EMF on the skin are very scarce [18,19].…”