täglich wiederholte Exposition, 2 h/Tag, 5 Tage/Woche, für 2 Jahre
Exposure was performed with a 902 MHzGSM or a 1747 MHzDCSsignal. Reference article: Ebert S, Berdinas Torres V, Frohlich J, Kuster N. 2006. SAR uniformity in Ferris wheel setups used in RF exposure of mice at 900 MHz. (In preparation).
The exposure signal applied consisted of three phases, each lasting 40 min: GSM Basic (non-DTX), GSM Talk consisting of random changes between the non-DTX (2/3) and DTX (1/3) modes, and GSM Environment consisting of a GSM Talksignal further amplitude-modulated by a statistically calculated power control function, based on data presented by Wiart et al. [2001, publication 12955]. Each timeslot was modulated with a standard random code.
Two exposure systems, one for each frequency, were located in separate rooms. Each system consisted of a signal generation unit, control and monitoring unit, and four "Ferris wheel" exposure units, one for each dose level (high, medium, low, and sham). The "Ferris wheel" concept developed by Balzano et al. [2000, publication 7306] was adopted and optimized for this study.
Each wheel, enabling exposure of up to 65 animals, consisted of two parallel, circular, stainless steel metal plates, 117 mm apart, with a conical (GSM) or bi-conical (DCS) antenna in their center, and stainless steel poles forming a short-cut of the cylindrical cavity at a radius of 755 mm. The animals, restrained in tubes similar to those used and approved for inhalation studies, were positioned at a radius (center of wheel to center of tubes) of 700 mm for GSM and 670 mm for DCS. In order to maintain a symmetrical load, missing animals were replaced by conical plastic tubes filled with 36 ml of liquid simulating the dielectrical parameters of muscle tissue. Higher modes were reduced by dielectric bricks between the animals at 902 MHz. Details of the setup and dosimetry are provided in Ebert et al.  (in preparation).
Male or female mice were each randomized by weight into 9 treatment groups: 2 x 4 RF dose groups (incl. sham) and one untreated cage control group. Loading and unloading of the exposure wheel was done first in/first out resulting in an additional restraint time of up to 32 min for each mouse. The study was performed blind to all scientists involved.
The maximum slot-averaged whole-body exposure (peak SAR level) was the same for all three phases; however, the resulting average SAR level varied: 100% (GSM Basic),70% (GSM Talk), and 26% (GSM Environment). These values have been averaged over 2 years.
Mess- und Berechnungsdetails
The incident field was adjusted according to a numerically determined dose-weight function in order to maintain the same exposure independent of the animal's weight/age. Exposure levels were monitored and automatically controlled using two electric field sensors inside each wheel. The dosimetry provided information about whole body, organ and peak spatial average SARs as well as about uncertainty and instant and lifetime variations. Values assessed using the methodology of Kuster et al. [2006, publication 13770] are presented in two tables. The whole-body exposure as well as the specific organSARs were several magnitudes larger than those of humans during phone or base station exposure. Several pre-tests showed that the high dose level was close to, yet below, the thermal threshold. [Ebert et al., 2005, publication 12740].
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