Medical/biological study (experimental study)

Mobile phone affects cerebral blood flow in humans. med./bio.

By: Aalto S, Haarala C, Bruck A, Sipila H, Hämäläinen H, Rinne JO

Published in: J Cereb Blood Flow Metab 2006; 26 (7): 885-890

Aim of study (acc. to author)

To study the effects of a mobile phone on regional cerebral blood flow in 12 healthy humans during exposure to electromagnetic field, while performing a verbal working memory task.

Background/further details

A substantially more sensitive experimental design (concerning the exposure) than in a previous study (publication 10384) was used.

Endpoint

effects on the neurological system: regional cerebral blood flow using positron emission tomography

Exposure

- mobile communications
- digital mobile phone

Exposure	Parameters
Exposure 1: 902 MHz Modulation type: pulsed Exposure duration: 51 mins	SAR: 1.51 W/kg peak value SAR: 0.743 W/kg average over mass (10 g)

Exposure 1

Main characteristics

Frequency	902 MHz
Type	electromagnetic field
Waveform	pulsed
Exposure duration	51 mins

Modulation

Modulation type	pulsed
Pulse width	0.577 ms
Repetition frequency	217 Hz
Additional info	Discontinuous mode was not activated.

Exposure setup

Exposure source	cellular phone
Distance between exposed object and exposure source	17 mm
Setup	The phone was placed between the subject`s head and the head rest of a positron emission tomography (PET) scanner parallel to the medial plane. The antenna was located circa 17 mm from the surface of the skull over the subject`s left inferior temporal lobe.
Sham exposure	A sham exposure was conducted.
Additional info	In order to eliminate audio clues the phone`s loudspeaker was removed and its battery was removed. It was operated with an external power source located 3 m away. The subjects were asked to insert an ear plug into the left ear. The EMF/sham exposure was started at the same moment as the transmission scan. After a 9 min transmission scan, each subject was scanned 14 times, out of which the first or the last seven scans were obtained during a constant EMF or sham exposure.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	1.51 W/kg	peak value	measured	-	-
SAR	0.743 W/kg	average over mass	measured	10 g	-

Additional parameter details

The effect of the PET scanner on the SAR was investigated with a SEMCAD V1.6 simulation and a MRI model which revealed that it increased the intensity of SAR 10g by circa 22%.

Measurement and calculation details

The SAR of the phone was measured with a Dosimetric Assessment System 4 (DASY4) and a generic twin phantom filled with brain tissue simulating liquid. The peak SAR value was measured near the position of the loudspeakers at the top part of the phone.

Exposed system:

human
partial body: left side of the head

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: regional cerebral blood flow (positron emission tomography) during performing a verbal working memory task (n-back task (1-back); reaction time, accuracy of responses)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

during exposure

Main outcome of study (acc. to author)

The data suggest that the electromagnetic field emitted by a mobile phone affects regional cerebral blood flow in humans. The results revealed that a mobile phone in operation induces a local decrease in regional cerebral blood flow beneath the antenna in the inferior temporal cortex and an increase more distantly in the prefrontal cortex.
The electromagnetic field had no effects on reaction times or the accuracy of responses in the working memory task.

Study character:

medical/biological study
experimental study
full/main study
double-blind study

Study funded by

not stated/no funding

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