Study type: Medical/biological study (experimental study)

Does evening exposure to mobile phone radiation affect subsequent melatonin production? med./bio.

By: Wood AW, Loughran SP, Stough C
Published in: Int J Radiat Biol 2006; 82 (2): 69-76
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Aim of study (acc. to author)

To study whether exposure to the emissions from a digital mobile phone prior to sleep alters the secretion of melatonin in 55 volunteers.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 895 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min
  • power: 0.25 W mean
  • SAR: 0.674 W/kg average over mass (10 g)
  • SAR: 0.11 W/kg maximum (cf. remarks)

Exposure 1

Main characteristics
Frequency 895 MHz
Type
Exposure duration continuous for 30 min
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
Additional info

standard GSM signal with no phase modulation nor 26th pulse blanking present
Exposure setup
Exposure source
Chamber Participants were instructed to sit and look at a white screen. Since the laboratory was an extremely quiet environment (purpose-built for sleep studies), a white noise signal was created by turning on the TV receiver tuned to an unused channel in order to mask any residual sound from the handset.
Setup A modified digital mobile phone transmitting in 'test mode' was controlled by a laptop computer via a data cable, which was disconnected after the output was set. The mobile phone was attached to a plastic arm mounted on a modified non-metallic welding helmet, and it rested against the subject's right cheek. The phone's loudspeaker circuit was disabled, and wads of plastic foam were placed in the pouch to absorb and eliminate aural cues from the buzzing of circuitry.
Additional info Volunteers were actively or sham exposed in a double-blind cross-over design in random order on successive Sunday nights, immediately prior to retiring to bed, and also prior to the attachment of recording electrodes and other sensors.
Parameters
Measurand Value Type Method Mass Remarks
power 0.25 W mean measured - -
SAR 0.674 W/kg average over mass measured 10 g -
SAR 0.11 W/kg maximum measured cf. remarks -
Additional parameter details

The peak SAR value was measured in-line with the phone's antenna over the area corresponding to the temporal lobe.

Measurement and calculation details

The power output of the phone was checked by an independent person using a test antenna connected to a power meter before handing it over to the experimenter, who was thus blind to the status of the phone. Phone outputs were also checked by an independent laboratory three times during the project. In addition, Specific Absorption Rate (SAR) measurements were conducted inside a Specific Anthropomorphic Mannequin (SAM) phantom using a precision robot RF Dosimetric Assessment System (DASY4).

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 total overnight melatonin secretion was unaffected by exposure to emissions from a mobile phone for 30 min in the period just prior to sleep. A significant reduction in 6-sulphatoxymelatonin relative to creatinine concentrations in pre-bedtime samples requires indipendent verification.

Study character:

Study funded by

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