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

Research output: Contribution to journalArticle

  • Authors:
  • Frank De Vocht
  • L. Liket
  • A. De Vocht
  • T. Mistry
  • P. Glover
  • And 2 others
  • External authors:
  • P. Gowland
  • H. Kromhout

Abstract

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 -1r.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. © 2007 The British Institute of Radiology.

Bibliographical metadata

Original languageEnglish
Pages (from-to)822-828
Number of pages6
JournalBritish Journal of Radiology
Volume80
Issue number958
DOIs
StatePublished - Oct 2007