Female mice (7 weeks old) were assigned to exposure groups (n=80) and three control groups (sham exposure: n=47; unsensitized controls: n=3, no sensitization, but challenge; solvent control: n=5). Different frequencies and power densities were examined. In the experiments of the delayed-type hypersensitivity (field 1 and 2) the animals were sensitized by topical application of highly concentrated dinitrochlorobenzene (DNCB) on the right ear. Later they were challenged with DNCB in lower concentration. To study the irritant contact sensitivity (field 3) tetradecanoylphorbol acetate was applied and the allergic reaction was estimated in terms of increased ear thickness.
|Exposure 1: 53.6 GHz|
|Exposure 2: 42.2 GHz|
|Exposure 3: 42.2 GHz|
for experiment 1 (Expo 1) animals were treated in four groups: 1.) sensitized with a topical application of 10 µl of 2.5% DNCB solution to the right ear + challenged with 10 µl of 0.6 % DNCB at the right ear + irradiated 2.) sensitized with a topical application of 10 µl of 2.5% DNCB solution to the right ear + challenged with 10 µl of 0.6 % DNCB at the right ear + sham irradiated 3.) not sensitized but challenged with 10 µl of 0.6 % DNCB at the right ear and not irradiated 4.) control group - neither sensitized nor challenged nor irradiated for experiment 2 (Expo 2) animals were treated in three groups: 1.) irradiated with 43.1 mW 2.) irradiated with 13.5 mW iii) sham irradiated
|Distance between exposed object and exposure source||5 mm|
|Setup||mice placed on a non-metallic hot-water thermostatic blanket set at 38°C; horn aperture positioned above the mid-back of the mice|
|Sham exposure||A sham exposure was conducted.|
|power||13.5 mW||mean||measured||-||± 0.5 mW|
|power density||12.7 mW/cm²||maximum||calculated||-||± 2.8 mW/cm²|
|SAR||254 W/kg||maximum||measured||-||± 55 W/kg|
|power||43.1 mW||mean||measured||-||± 3.1 mW|
|power density||42.4 mW/cm²||maximum||calculated||-||± 7.7 mW/cm²|
|SAR||849 W/kg||maximum||measured||-||± 153 W/kg|
The 53.6 GHz exposed animals showed a significant enhancement of the delayed-type hypersensitivity reaction compared with the sham exposure animals. The unsensitized group showed only a low-grade delayed-type hypersensitivity response. The solvent control group did not show any delayed-type hypersensitivity response.
In the 42.2 GHz, 13.5 mW exposed animals no significant difference in ear thickness was observed compared to the sham exposure group. In the 43.1 mW group a significant enhancement of the delayed-type hypersensitivity reaction compared with the sham exposure animals was observed.
The investigation of the irritant contact sensitivity did not reveal any difference in ear thickness between the irradiated animals compared to the sham exposure group.