Exposure to alternating electromagnetic fields and effects on the visual and visuomotor systems

Exposure to alternating electromagnetic fields and effects on the visual and visuomotor systems

Acute effects on the visual and visuo-motor systems by exposure to electromagnetic fields (EMFs) at a frequency and amplitude similar to those produced by MR imaging gradient coils were assessed. 40 volunteers were exposed in random order to three, time varying, magnetic field gradients (0, 20 and 1...

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Bibliographic Details
Published in:British journal of radiology Vol. 80; no. 958; pp. 822 - 828
Main Authors: DE VOCHT, F, LIKET, L, DE VOCHT, A, MISTRY, T, GLOVER, P, GOWLAND, P, KROMHOUT, H
Format: Journal Article
Language:English
Published: London British Institute of Radiology 01-10-2007
Subjects:
Adult
Biological and medical sciences
Cross-Over Studies
Double-Blind Method
Electromagnetic Fields - adverse effects
Female
Humans
Investigative techniques, diagnostic techniques (general aspects)
Magnetic Resonance Imaging - adverse effects
Male
Medical sciences
Middle Aged
Neuropsychological Tests
Psychomotor Performance - radiation effects
United Kingdom
Visual Perception - radiation effects
Performance evaluation
Human
Nuclear medicine
Sensitivity
Radiology
Medical imagery
Nuclear magnetic resonance imaging
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Summary:Acute effects on the visual and visuo-motor systems by exposure to electromagnetic fields (EMFs) at a frequency and amplitude similar to those produced by MR imaging gradient coils were assessed. 40 volunteers were exposed in random order to three, time varying, magnetic field gradients (0, 20 and 10 mT m(-1)r.m.s.). The waveform was 50 cycles of a 490 Hz sinusoidal waveform repeated every second with a total duration of 10 min for each trial. The EMFs were generated using an in-house designed and built magnetic gradient coil and waveform generator. During each trial, a test battery assessing the visual sensory (FACT) and visuo-motor (Pursuit Aiming II and visual tracking) neurobehavioral domains was completed by all volunteers. The sequence of these tests was assigned at random for each volunteer. Performance in these tests was analysed using linear mixed effects models adjusted for confounding factors collected in a pre-trial questionnaire. Variability of the estimates was assessed using a delete-1 jack-knife procedure. There was a trend for visuo-motor accuracy to be reduced (p = 0.06) by 1% during high exposure, but not at medium exposure. There was a weaker trend for visual contrast sensitivity to be improved by 12% and 21% during medium and high exposure, respectively, compared with the non-exposed sessions (p = 0.08). These effects did not reach 5% statistical significance within a population of 40 volunteers, but also the magnitude of these effects did not depend on single "extreme" observations.
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ISSN:0007-1285
1748-880X
DOI:10.1259/bjr/22263979