There is increasing evidence that pulse-modulated radio frequency electromagnetic fields (RF EMF), such as emitted by mobile phones, can alter brain physiology even at intensities below the current exposure limits. The reported effects include changes in electrical activity (EEG, ERP), regional cerebral blood flow (rCBF), intracortical excitability and cognitive function. However, conclusions about possible adverse effects on human health are premature as the underlying mechanisms of these non-thermal effects are unknown.
The electromagnetic spectrum can be divided according to the photon energy or equivalently according to wavelength (λ) or frequency (f). The spectrum has two important divisions: non-ionizing radiation (radiation that does not carry enough energy per quantum to ionize atoms or molecules) and ionizing radiation (radiation that has the potential to ionize an atom or molecule through atomic interactions). It ranges from extremely low frequencies (e.g. power lines), radio frequency and microwave radiation, to infrared, ultraviolet and x-ray radiation. Mobile phone technology facilitates frequencies between 400 MHz - 2.3 GHz.
Currently the Global System for Mobile Communication (GSM) is the most widely used mobile voice communication system in Europe and is operated in frequency bands at 900 and 1800 MHz. The Universal Mobile Telecommunications System (UMTS) is the third generation of wireless mobile networks and is operated at 2 GHz.
The Specific Absorption Rate (SAR) is a measure of the amount of radio frequency energy absorbed by the body. International limits for local exposures, i.e., peak spatial SAR averaged over any 10 g of tissue, are 2 W/kg for the general public and 10 W/kg for occupational exposure (ICNIRP, 1998).
A typical exposure setup as used in our studies is illustrated in Fig. 2 (right) and the distribution of the SAR when exposing the right hemisphere (right antenna activated) is depicted on the left.
Main Goals, Keywords
Our research is conducted in close collaboration with the IT' IS foundation (Foundation for Research on Information Technologies in Society).