Study type: Medical/biological study (experimental study)

Search for frequency-specific effects of millimeter-wave radiation on isolated nerve function. med./bio.

Published in: Bioelectromagnetics 1997; 18 (4): 324-334

Aim of study (acc. to author)

The aim of the study was to verify the existence of specific effects of millimeter waves on excitable tissues. The effects of a short-term exposure to millimeter waves on the compound action potential conduction in an isolated frog sciatic nerve preparation were investigated. Compound action potentials were evoked by either a low-rate or a high-rate electrical stimulation of the nerve (4 and 20 paired pulses/s, respectively).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 41.15–51.7 GHz
Modulation type: CW
Exposure duration: 30 min
Exposure 2: 40.5–51.8 GHz
Modulation type: CW
Exposure duration: 10 - 60 min

Exposure 1

Main characteristics
Frequency 41.15–51.7 GHz
Type
Exposure duration 30 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 0.052 m
Setup sciatic nerves were laid in the slot of the exposure chamber and exposed under thin layer of mineral oil; the nerve was aligned with the E-field.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.26 mW/cm² minimum measured - -
power density 2.6 mW/cm² maximum measured - -

Exposure 2

Main characteristics
Frequency 40.5–51.8 GHz
Type
Exposure duration 10 - 60 min
Additional info frequency changed in steps of 0.01 GHz/min or 0.1 GHz/min
Modulation
Modulation type CW
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.23 mW/cm² minimum measured - -
power density 3 mW/cm² maximum measured - -

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The low-rate stimulation (field 1-9) did not change the functional state of the nerve, and the amplitude, latency, and peak latency of compound action potentials could stay virtually stable for hours. Microwave exposure for 10-60 min at 0.24-1.5 mW/cm², either at various constant frequencies or with a stepwise frequency change, did not cause any detectable alterations in compound action potential conduction.
The high-rate electrical stimulation produced gradual and reversible decrease of the amplitude of test compound action potentials and increased their latencies and peak latencies. These changes were essentially the same with and without irradiation, except for attenuation of the decrease of the test compound action potential amplitude. This effect was revealed at both field intensities, but was statistically significant only for certain frequencies of the irradiation. Within the studied limits, this effect appeared to be dependent on the frequency rather than on the intensity of the irradiation, but this observation requires additional experimental confirmation.

Study character:

Study funded by

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