Harmful effects of electromagnetic fields (EMF) on cognitive and behavioural features of humans and rodents have been controversially discussed and raised persistent concern about adverse effects of EMF on general brain functions. In the present study we applied radio-frequency (RF) signals of the Universal Mobile Telecommunications System (UMTS) to full brain exposed male Wistar rats in order to elaborate putative influences on stress hormone release (corticosteron; CORT and adrenocorticotropic hormone; ACTH) and on hippocampal derived synaptic long-term plasticity (LTP) and depression (LTD) as electrophysiological hallmarks for memory storage and memory consolidation. Exposure was computer controlled providing blind conditions. Nominal brain-averaged specific absorption rates (SAR) as a measure of applied mass-related dissipated RF power were 0, 2, and 10 W/kg over a period of 120 min. Comparison of cage exposed animals revealed, regardless of EMF exposure, significantly increased CORT and ACTH levels which corresponded with generally decreased field potential slopes and amplitudes in hippocampal LTP and LTD. Animals following SAR exposure of 2 W/kg (averaged over the whole brain of 2.3 g tissue mass) did not differ from the sham-exposed group in LTP and LTD experiments. In contrast, a significant reduction in LTP and LTD was observed at the high power rate of SAR (10 W/kg). The results demonstrate that a rate of 2 W/kg displays no adverse impact on LTP and LTD, while 10 W/kg leads to significant effects on the electrophysiological parameters, which can be clearly distinguished from the stress derived background. Our findings suggest that UMTS exposure with SAR in the range of 2 W/kg is not harmful to critical markers for memory storage and memory consolidation, however, an influence of UMTS at high energy absorption rates (10 W/kg) cannot be excluded.

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The development and analysis of three waveguides for the exposure of small biological in vitro samples to mobile communication signals at 900 MHz (GSM, Global System for Mobile Communications), 1.8 GHz (GSM), and 2 GHz (UMTS, Universal Mobile Telecommunications System) is presented. The waveguides were based on a fin-line concept and the chamber containing the samples bathed in extracellular solution was placed onto two fins with a slot in between, where the exposure field concentrates. Measures were taken to allow for patch clamp recordings during radiofrequency (RF) exposure. The necessary power for the achievement of the maximum desired specific absorption rate (SAR) of 20 W/kg (average over the mass of the solution) was approximately P(in)  = 50 mW, P(in)  = 19 mW, and P(in)  = 18 mW for the 900 MHz, 1800 MHz, and 2 GHz devices, respectively. At 20 W/kg, a slight RF-induced temperature elevation in the solution of no more than 0.3 °C was detected, while no thermal offsets due to the electromagnetic exposure could be detected at the lower SAR settings (2, 0.2, and 0.02 W/kg). A deviation of 10% from the intended solution volume yielded a calculated SAR deviation of 8% from the desired value. A maximum ±10% variation in the local SAR could occur when the position of the patch clamp electrode was altered within the area where the cells to be investigated were located.

Radial waveguide set-ups are introduced as exposure devices for long-term experiments with large numbers of non-restrained animals exposed simultaneously. Methods are presented to ensure well-defined exposure conditions even for potentially overmoded waveguides and for the exposure of large groups of animals per cage. The proposed methods are applied for a four-generation study being performed on up to 2500 mice exposed to a generic UMTS test signal at prescribed averaged whole body specific absorption rates (SARs). The variation of the whole body SAR due to the movement of the mice inside the cage is calculated by using the finite-difference time-domain method and detailed animal models for selected configurations of the mice inside the cage for all stages of the study.

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For the assessment of safe distances which guarantee that the occupational exposure of persons working at mobile communication base station antenna sites complies with the relevant guidelines, numerical computations of the electromagnetic field and SAR distributions inside human body models with various body weights of 42, 70, and 110 kg in front of six widely-used single-, dual-and multi-band antennas are presented. The maximum whole-body averaged SAR always occurs for a centered position of the human body with respect to the main beam direction. For positions of a person beside and behind the antenna the absorption is drastically reduced. It turns out that for each antenna the whole-body SAR of the 42-kg body model is the limiting factor for the compliance distance. Compared to the 110-kg model the 42-kg model generates whole-body SAR values which are larger by a factor of approx. 1.7 on average for the considered antennas. Computed SAR values are related to the recommended basic restrictions (0.4 W/kg whole body SAR) and represented as maximum permissible radiated power levels as a function of antenna-to-body distance.

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The development of exposure devices for investigating possible effects of mobile communication systems to nonrestrained animals aims at ahomogeneous field distribution in the area the animals occupy.In the presented 900 MHz exposure device based on amodified rectangular waveguide (WR1150)aquite good field homogeneity of 5% (including the standing wave contributiondue to internal reflections) is achieved in the cage region mainly by flattening the transverse field. Agood agreement exists between numerical and analytical results. The desired maximalwhole-body specific absorption rate (SAR) of 4W/kg in the Djungarian hamster model is reached at an input power of only 3.4 W.