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Electromagnetic Fields in Biological Systems
to ELF-EMF for either 1 hour or 4 hours. The authors found that ELF-EMF reduced the
latency to find a hidden platform and improved long-term memory of former location
of the platform without affecting short-term memory and motor activity. These findings
indicate that ELF-EMF exerts a positive effect on the acquisition and maintenance of
spatial memory.
Shin et al. (2007) demonstrated that exposure to ELF-EMF (60 Hz, 2.4 mT, 1 h/day for
1 or 7 days) enhanced dopamine levels in rat striatum. The authors examined the role of
dopaminergic receptors in ELF-EMF-induced behavioral changes. They suggested that
ELF-EMF-induced behavioral responses are, at least in part, mediated by the activation
of dopamine D 1 -like receptors.
Burda et al. (2009) showed that the ELF-EMF generated by high-voltage power lines
disrupts the alignment of bodies of animals with the geomagnetic field. Body orientation of cattle and roe deer was random on pastures under or near power lines. Moreover,
cattle exposed to various magnetic fields directly beneath or in the vicinity of power
lines trending in various magnetic directions exhibited distinct patterns of alignment.
The disturbing effect of ELF-EMF on body alignment diminished with distance of the
body from the conductors. The authors provided evidence for magnetic sensation in
large mammals as well as evidence for an overt behavioral reaction to weak ELF-EMF
in vertebrates.
In human studies, de Vocht et al. (2007) investigated the impact of exposure to
“stray” magnetic field from a whole-body 7-T MRI scanner on neurobehavioral performance and cognition. Twenty-seven volunteers completed four sessions, which comprised 1.6-T (twice), 0.8-T, and negligible exposure sessions. During three sessions, the
volunteers were instructed to complete a series of standardized head movements to generate additional time-varying fields (300 and 150 mT/s). The results suggested that there
are effects on visual perception and hand-eye coordination; but these were found to
be weak and variable between studies. The magnitude of these effects may depend on the
magnitude of time-varying fields and not so much on SMF. Although this study did not
include exposure above 1.6 T, it suggested that the use of strong magnetic fields is not a
significant confounder in fMRI studies of cognitive function.
Cavin et al. (2007) examined an initial characterization of the metallic taste effect in
some workers when moving around a 7-T MRI scanner. This study indicated that 50%
of subjects perceive a metallic taste for head shaking with a period of 1.5 seconds (magnetic field in an anterior–posterior direction) causing a dB/dt of 2.3 ± 0.3 T/s. Presence
of dental fillings is not a requirement for the sensation of metallic taste.
Schlamann et al. (2010) assessed potential cognitive deficits under the influence of
an SMF at various field strengths that some other studies had already reported. Mostly
no MRI sequences were performed. All subjects underwent one MRI examination for
63 minutes at 1.5 T and one at 7 T within an interval of 10–30 days. The order of the
examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Only six subtests revealed significant differences between pre- and post-MRI
conditions. In these tests, the subjects achieved better results in post-MRI testing than
in pre-MRI testing. The other tests revealed no significant results. The improvement in
post-MRI testing is only explicable in terms of learning effects. The authors concluded