Study type: Medical/biological study (experimental study)

Human cognitive performance in a 3 mT power-line frequency magnetic field. med./bio.

Published in: Bioelectromagnetics 2011; 32 (8): 620-633

Aim of study (acc. to author)

To study the impact of a 60 Hz, 3 mT magnetic field on human cognitive performance (both correctness of response and speed of completion).

Background/further details

99 subjects participated (60 female, 39 male). The participants were randomly assigned to one of three experimental groups, which determined the order and presence of the magnetic field exposure conditions: group 1 (sham exposure/sham exposure), group 2 (exposure/sham exposure), and group 3 (sham exposure/exposure).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: continuous for a 30 min block before or following a sham exposure block (also 30 min) with a 30 min rest period in between

General information

Test persons were divided into three exposure groups: i) sham exposure/sham expsoure ii) magnetic field exposure/sham exposure iii) sham exposure/magnetic field exposure

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration continuous for a 30 min block before or following a sham exposure block (also 30 min) with a 30 min rest period in between
Exposure setup
Exposure source
Setup two octagonal Helmholtz coils consisting of 158 turns of 10-gauge copper wire and encased within plastic; 1.6 m wide and spaced 1.2 m apart parallel to each other; coils placed in a plastic frame, elevated 80 cm from the ground; non-conductive coolant tubing bordered the coils; participant seated between the coils, fitted with ear-plugs; field centered in the region of the participant's head and homogeneous within 5 % in this area
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 3 mT effective value - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Performance between repetitions (the two (sham) exposure blocks) improved in 11 of 15 psychometric parameters (practice effect). A significant effect on the digit span forward test (see digit span test) revealed an absence of practice effects for both exposure groups but not the control group. This memory test indicates magnetic field-induced abolition of the improvement associated with practice. Overall, the data do not indicate any clear magnetic field effect on human cognition.

Study character:

Study funded by

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