Study type: Medical/biological study (experimental study)

Effects of millimeter wavelength electromagnetic radiation on neurons: electrophysiological study med./bio.

Published in: Crit Rev Biomed Eng 2000; 28 (5-6): 52-59

Aim of study (acc. to author)

To clarify if millimeter wave irradiation can effect the spontaneous firing rate of neurons.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 61.22 GHz
Modulation type: CW
Exposure duration: continuous for about 12 min
  • power density: 130 mW/cm² maximum (0-130 mW/cm²)
  • SAR: 4,200 W/kg maximum (0-4200 W/kg; e.g., 650, 1550, 2800, 3150 W/kg)
Exposure 2: 75 GHz
Modulation type: CW
Exposure duration: continuous for about 12 min
  • power density: 130 mW/cm² maximum (0-130 mW/cm²)
  • SAR: 4,200 W/kg maximum (0-4200 W/kg; e.g., 650, 1550, 2800, 3150 W/kg)

Exposure 1

Main characteristics
Frequency 61.22 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for about 12 min
Modulation
Modulation type CW
Exposure setup
Exposure source
  • waveguide
  • rectangular, 3.6 mm x 1.8 mm, G4-142 device
Chamber The end of the waveguide was isolated from the physiological solution by Teflon tape.
Setup The prepared nerve ring was placed in an acrylic resin cell containing 2 ml of physiological solution and was attached to the wax foundation with cactaceous thorns.
Additional info In control experiments, the solution was heated by 2°C with a rate of 0.96°C/s corresponding to an SAR of 4030 W/kg.
Parameters
Measurand Value Type Method Mass Remarks
power density 130 mW/cm² maximum - - 0-130 mW/cm²
SAR 4,200 W/kg maximum measured - 0-4200 W/kg; e.g., 650, 1550, 2800, 3150 W/kg

Exposure 2

Main characteristics
Frequency 75 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for about 12 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 130 mW/cm² maximum - - 0-130 mW/cm²
SAR 4,200 W/kg maximum measured - 0-4200 W/kg; e.g., 650, 1550, 2800, 3150 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The findings indicate that millimeter wave exposure at the power used in treatment can activate thermoreceptors and other temperature-sensitive nerve endings located in superficial skin layers.
On normal physiological conditions, the BP-4 neuron fires with a steady frequency. After starting irradiation, the firing rate decreased. With increasing SAR, this effect also increased (e.g. stronger decrease of the firing rate). Under prolonged exposure, after starting the irradiation, the firing rate decreased (in proportion to SAR) and then gradually increased to the level exceeding the initial value of the firing rate. After the completion of exposure at first, the firing rate increased and the gradually decreased towards the new level approximate to the initial value of the firing rate. The effects observed at the same SAR did not depend on the frequency.

Study character:

Study funded by

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