Study type: Medical/biological study (experimental study)

Effects of exposure of the ear to GSM microwaves: in vivo and in vitro experimental studies med./bio.

By: Aran JM, Carrere N, Chalan Y, Dulou PE, Larrieu S, Letenneur L, Veyret B, Dulon D
Published in: Int J Audiol 2004; 43 (9): 545-554
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Aim of study (acc. to author)

To study the effects of mobile phone (GSM) microwaves on the ears of guinea pigs in in vivo and in in vitro experiments.

Background/further details

Since the brain is also exposed to the microwaves, changes in auditory functions could be caused by action at the level of the inner ear and/or central auditory pathways. The experiments were aimed at monitoring separately peripheral (by DPOAE measurements) and central auditory functions (auditory brainstem responses) after microwave exposure of the animals.
In the in vivo experiment, groups of eight guinea pigs had their left ear exposed to GSM microwaves and distortion product otoacoustic emissions (DPOAEs) were measured and auditory brainstem response thresholds were monitored.
In vitro, the two organs of Corti of 15 newborn rats were isolated and placed in culture.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 1 h/day, 5 days/week, for 2 months
Exposure 2: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 24 h
  • SAR: 1 W/kg unspecified

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Exposure duration repeated daily exposure, 1 h/day, 5 days/week, for 2 months
Additional info in vivo
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM modulation
Exposure setup
Exposure source
Chamber An eight-compartment setup was constructed from RF absorbing panels avoiding interference among antennas.
Setup Guinea pigs were held in a holding device composed of two sliding-yoke PVC tubes each with a V notch providing a hole for the neck in order to keep the head outside the tube and maintained straight by a sliding ring adjusted over the nose of the animal. The animal body could lie comfortably on a platform inside the tube assembly. The antenna was fixed horizontally at the level of the external auditory canal of the left ear in contact with the edge of the pinna.
Additional info Sham exposure took place under the same conditions but in the absence of RF field.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 W/kg mean measured - -
SAR 2 W/kg mean measured - -
SAR 4 W/kg mean measured - -
Measurement and calculation details

Local SAR measurements were made on an anaesthetized guinea pig using a temperature probe inserted into the cochlea. The average of three measurements at 7, 17 and 34 W input to the loop antenna gave an SAR of 3.5 ± 0.4 W/kg per incident watt in the cochlea.

Exposure 2

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 24 h
Additional info in vitro
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM modulation
Exposure setup
Exposure source
Chamber Two pieces of wire-patch cell (WPC) apparatus (see reference article) were used to expose the organs of Corti (OCs) in Petri dishes. Each WPC was placed in its own incubator for true blind operation.
Setup The WPC consisted of two parallel square metallic plates with the bottom one being powered with RF through a coaxial line passing through the top one. Four poles at the four corners between the plates allowed for optimal tuning of the device.
Additional info For each rat, one OC was exposed, and the other one was sham-exposed.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 W/kg unspecified measured - -
Measurement and calculation details

Extensive dosimetric measurements showed that the uniformity of the SAR in the culture medium was very good (< 15%).

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The data showed no difference in DPOAE amplitudes or in auditory brainstem response thresholds between the exposed and non-exposed ears/groups.
Corti organs all appeared normal at this stage of development.
These data provided no evidence that microwave irradiation, at the levels produced by mobile phones, caused damage to the inner ear or the auditory pathways in the animals.

Study character:

Study funded by

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