Study type: Medical/biological study (experimental study)

Effects of exposure to low level radiofrequency fields on acetylcholine release in hippocampus of freely moving rats med./bio.

By: Testylier G, Tonduli L, Malabiau R, Debouzy JC
Published in: Bioelectromagnetics 2002; 23 (4): 249-255
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Aim of study (acc. to author)

The authors used microdialysis to study acetylcholine (ACh) release in the hippocampus of freely moving rats after acute irradiation with two radiofrequency fields, using power density under permissible levels.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 1 h
  • power density: 2 mW/cm² unspecified
  • SAR: 3.26 W/kg average over mass (whole body)
  • power density: 4 mW/cm² unspecified
  • SAR: 6.52 W/kg average over mass (whole body)
Exposure 2: 800 MHz
Modulation type: AM
Exposure duration: continuous for 1 or 14 h
  • power density: 0.2 mW/cm² unspecified
  • SAR: 0.325 W/kg average over mass (whole body)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
Exposure duration continuous for 1 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 60 cm
Chamber The rats were placed individually in a narrow Teflon cage (W 15 cm x L 30 cm x H 30 cm) with their main body axis parallel to the magnetic component of the field.
Setup The cage was positioned with its input face at 60 cm from the antenna and its bottom 5 cm under the axis.
Sham exposure A sham exposure was conducted.
Additional info The rectangular horn antennas had a horizontal great axis, so they emitted a horizontal magnetic component and a vertical electric component.
Parameters
Measurand Value Type Method Mass Remarks
power density 2 mW/cm² unspecified measured - -
SAR 3.26 W/kg average over mass estimated whole body -
power density 4 mW/cm² unspecified measured - -
SAR 6.52 W/kg average over mass estimated whole body -
Additional parameter details

At 2.45 GHz, the cage was at the limit of the near field. The power density was maximal on the axis of the antenna and showed a uniform decrease with distance down to 30% at the edge of the cage.

Measurement and calculation details

At the beginning of exposures, field power density was measured at a reference point on the axis of the antenna at the input plane of the cage. A rough calculation of the SAR was performed using the formula: SAR (W/kg) = σE²/2ρ, where σ (Siemens/m) is the conductivity of brain tissue, ρ (kg/m³) its density and E (V/m) the electric field.

Exposure 2

Main characteristics
Frequency 800 MHz
Type
Charakteristic
Exposure duration continuous for 1 or 14 h
Modulation
Modulation type AM
Modulation frequency 32 Hz
Additional info

[Kunjilwar and Behari, 1993]
Exposure setup
Exposure source
Distance between exposed object and exposure source 16 cm
Setup The cage was positioned with its input face at 16 cm from the antenna and its bottom 5 cm under the axis.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.2 mW/cm² unspecified measured - -
SAR 0.325 W/kg average over mass estimated whole body -
Additional parameter details

The mean power density in the cage was 61 ± 25% SD of the indicated reference value.

Measurement and calculation details

At the beginning of exposures, field power density was measured at a reference point which was the midpoint of the bottom of the cage wall facing the antenna horn.

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

After exposure to 2.45 GHz radiofrequency, rats exposed at 2 mW/cm² did not show a significant modification of ACh release, whereas those exposed at 4 mW/cm² showed a significant 40% decrease in mean ACh release (this decrease was maximal at 5h post exposure). Irradiation to the 800 MHz radiofrequency for 1 h did not cause any significant effect, but exposure for 14 hours induced a significant 43% decrease in ACh release during the period 11 p.m.-4 a.m. compared to control rats. In the control group the authors observed an increase of ACh release at the beginning of the night, which was linked to the waking period of rats. The results indicate that neurochemical modification of the hippocampal cholinergic system can be observed during and after an exposure to low intensity radiofrequency.

Study character:

Study funded by

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