Study type: Medical/biological study (experimental study)

EEG changes as heat stress reactions in rats irradiated by high intensity 35 GHz millimeter waves. med./bio.

Published in: Health Phys 2011; 100 (6): 632-640

Aim of study (acc. to author)

To study the stress reactions in rats evoked by over-exposure to 35 GHz millimeter waves.

Background/further details

24 rats were divided into eight groups (according to the power flux densities; each group n=3) and skin temperature of the shaved back was measured before, during and after exposure under anaesthesia. Additionally, 48 rats with implanted electrodes were divided into eight groups (each group n=6) and exposed in restrained position.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 35 GHz
Modulation type: pulsed
Exposure duration: continuous for 30 s

General information

Rats were divided into eight groups: i) exposure to 0.5 W/cm² over an area of 3.6 cm² ii) exposure to 0.9 W/cm² over an area of 3.6 cm² iii) exposure to 1.2 W/cm² over an area of 3.6 cm² iv) exposure to 1.5 W/cm² over an area of 3.6 cm² v) exposure to 1.5 W/cm² over an area of 1.8 cm² vi) exposure to 3.5 W/cm² over an area of 1.8 cm² vii) exposure to 5.0 W/cm² over an area of 1.8 cm² viii) exposure to 7.5 W/cm² over an area of 1.8 cm²

Exposure 1

Main characteristics
Frequency 35 GHz
Type
Exposure duration continuous for 30 s
Modulation
Modulation type pulsed
Pulse width 1 µs
Additional info

two pulse trains were employed: a) 500 pulses/s b) 1000 pulses/s

Exposure setup
Exposure source
Chamber screened exposure chamber with the antenna inside the chamber
Setup exposure beam directed to the rat's back; for EEG recording rat fixed by rubberized fabrics on a plastic board on the object stage of the exposure chamber; for temperature measurments rats anaesthetized
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 40 kW peak value - - -
power density 0.5 W/cm² - - - for an exposure area of 3.6 cm²
power density 1.2 W/cm² - - - for an exposure area of 3.6 cm²
power density 0.9 W/cm² - - - for an exposure area of 3.6 cm²
power density 1.5 W/cm² - - - for an exposure area of 3.6 cm²
power density 1.5 W/cm² - - - for an exposure area of 1.8 cm²
power density 3.5 W/cm² - - - for an exposure area of 1.8 cm²
power density 5 W/cm² - - - for an exposure area of 1.8 cm²
power density 7.5 W/cm² - - - for an exposure area of 1.8 cm²

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The data showed that stress reactions (indicated by EEG analysis) are more intense during the first part of the irradiation than during the later part: stress reactions began at the first second and the intensities of stress reactions were much higher during the 1st-17th s than during the 17th-30th s. The skin temperature increase (thermal pain) produced by millimeter wave exposure was the principle reason for stress reactions. As expected, at the higher levels of irradiation, the stress reaction time decreased and the stress reaction intensity increased.

Study character:

Study funded by

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