Medical/biological study (experimental study)

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

By: Corbacio M, Brown S, Dubois S, Goulet D, Prato FS, Thomas AW, Legros A

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

cognitive/behavioral endpoints: cognitive performance

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	magnetic flux density: 3 mT effective value

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	magnetic field
Waveform	sinusoidal
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	Helmholtz coils
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:

human
whole body

Methods Endpoint/measurement parameters/methodology

cognitive/behavioral endpoints: cognitive performance (different psychometric tests, e.g. digit span test, stroop test, digit symbol coding (processing speed, visual motor coordination), block design test (spatial perception, visual abstract processing, problem solving, processing speed), arithmetic test (working memory, numerical reasoning), trail making test, mental rotation test (spatial perception, manipulation performance, processing speed), Fitts' motor task (motor coordination, processing speed))

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

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:

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

Study funded by

Canadian Institutes of Health Research (CIHR)
Electricité de France (EDF)
Hydro-Québec, Canada
Réseau de Transport d'Electricité (RTE), France

Li L et al. (2014): No effects of power line frequency extremely low frequency electromagnetic field exposure on selected neurobehavior tests of workers inspecting transformers and distribution line stations versus controls
Liu T et al. (2008): Chronic exposure to low-intensity magnetic field improves acquisition and maintenance of memory
Fu Y et al. (2008): Long-term exposure to extremely low-frequency magnetic fields impairs spatial recognition memory in mice
Ross ML et al. (2008): Physiologically patterned weak magnetic fields applied over left frontal lobe increase acceptance of false statements as true
Jadidi M et al. (2007): Acute exposure to a 50 Hz magnetic field impairs consolidation of spatial memory in rats
Nevelsteen S et al. (2007): Effects of information and 50 Hz magnetic fields on cognitive performance and reported symptoms
Legros A et al. (2006): Individual subject sensitivity to extremely low frequency magnetic field
Legros A et al. (2006): Transient effect of low-intensity magnetic field on human motor control
Delhez M et al. (2004): No influence of 20 and 400 µT, 50 Hz magnetic field exposure on cognitive function in humans
Kurokawa Y et al. (2003): No influence of short-term exposure to 50-Hz magnetic fields on cognitive performance function in human
Crasson M (2003): 50-60 Hz electric and magnetic field effects on cognitive function in humans: a review
Trimmel M et al. (1998): Effects of an ELF (50 Hz, 1 mT) electromagnetic field (EMF) on concentration in visual attention, perception and memory including effects of EMF sensitivity
Preece AW et al. (1998): The effect of a 50 Hz magnetic field on cognitive function in humans