Study type: Medical/biological study (experimental study)

Effects of microwaves (900 MHz) on the cochlear receptor: exposure systems and preliminary results med./bio.

By: Marino C, Cristalli G, Galloni P, Pasqualetti P, Piscitelli M, Lovisolo GA
Published in: Radiat Environ Biophys 2000; 39 (2): 131-136
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Aim of study (acc. to author)

To assess potential changes occuring in the cochlear receptor after exposure to electromagnetic fields of a given frequency (around 900 MHz) and a low intensity.

Background/further details

A cubic chamber was developed and a routine acoustic apparatus employed to observe otofunctional effects. In this paper, the methodological approach and the experimental set-up are described, and the first preliminary results of the cochlear receptor functionality are reported.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 950 MHz
Modulation type: CW
Exposure duration: repeated daily exposure, 3 h/day, for 3 days
Exposure 2: 936 MHz
Modulation type: CW
Exposure duration: repeated daily exposure, 3 h/day, for 5 days

Exposure 1

Main characteristics
Frequency 950 MHz
Type
Charakteristic
Exposure duration repeated daily exposure, 3 h/day, for 3 days
Additional info vertical polarisation
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 65 cm
Chamber cubic chamber (side 1.2 m) shielded with copper sheets and lined with RF absorbing material (-20 dB)
Setup Eight rats immobilised in cylindrical (D=4.5 cm, L=12 cm) Lucite jigs, ending with a cone, were positioned with their heads facing the mouth of the antenna at 65 cm and their longitudinal axis oriented along the direction of propagation. There were two arrays of four jigs at 50 and 60 cm from the ground over an acrylic support.
Sham exposure A sham exposure was conducted.
Additional info Fiberoptic thermosensors were placed on the skin of one rat in the jig during the first day of exposure to monitor any change of temperature.
Parameters
Measurand Value Type Method Mass Remarks
power density 4.58 W/m² unspecified measured - -
SAR 0.2 W/kg mean measured and calculated unspecified max. 0.32 W/kg
power density 23 W/m² unspecified measured - -
SAR 1 W/kg mean measured and calculated unspecified max. 1.6 W/kg
Additional parameter details

The power density was measured in air at 65 cm from the source. The SAR value was obtained as the average of six measurement points in the head of a rat phantom.

Measurement and calculation details

The E-field was measured along the horn antenna axis in air and in brain equivalent tissue using an isotropic probe [Schmid et al., 1996]. The SAR distribution along the longitudinal axis of a homogeneous phantom irradiated by a plane wave at 940±10 MHz was simulated by the HFSS code and verified by SAR measurements using a calibrated E-field probe in rat phantoms filled with 300 g of homogeneous semisolid tissue-equivalent material.

Exposure 2

Main characteristics
Frequency 936 MHz
Type
Charakteristic
Exposure duration repeated daily exposure, 3 h/day, for 5 days
Additional info vertical polarisation
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 65 cm
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 23 W/m² unspecified measured - -
SAR 1 W/kg mean measured and calculated unspecified -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The exposure system and the diagnostic apparatus are extremely useful to investigate a potential effect on the auditory system. However, with the parameters applied in these experiments, no evidence for a biological effect was observed.

Study character:

Study funded by

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