To determine if gene expression changes occur in white blood cells of volunteers exposed to an extremely low frequency magnetic field, each of 17 male volunteer pairs was subjected either to a 50 Hz magnetic field for 2 h or to a sham exposure at the same time (11-13 h).
The alternative regime for each volunteer was repeated on the following day and the two-day sequence was repeated 6 days later, with the exception that a null exposure replaced the sham exposure.
Five blood samples were collected at 2 h intervals (from 9-17 h) with five additional samples during the exposure and sham exposure or null exposure (at 5, 10, 20, 40 and 80 min). RNA samples were pooled for the same time on each study day for the group of 17 volunteers.
Exposure duration: continuous for 120 min
Each the 17 volunteer pairs underwent a sequence of exposure followed by a sham exposure on consecutive days in the first week, which was repeated the following week with the exception that the sham exposure was replaced by a null exposure. The other volunteer in each pair simultaneously underwent the reverse exposure sequences.
|Setup||two exposure frames (1 m³) consisted of an acrylic former upon which the field-generating coils were wound on each of the vertical sides; coils were wound with 100 turns with two interleaved sets of 50 turns, which permitted current flow to be in the same or opposite directions; if the current is unidirectional through the two sets of windings, a field is generated; when the currents passing through the two coils are in opposing directions, a sham exposure is produced in which the field strength is cancelled, but other conditions, such as total current remain the same; the two frames were 5.4 m apart in the study room; volunteer sat within exposure frame|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||62 µT||-||measured||-||± 7.1 µT (at the center of the frame)|
No genes or gene sets showed consistent response profiles to extremely low frequency magnetic field exposures. A stress response was detected as a transient increase in plasma cortisol at the onset of either exposure or sham exposure on the first study day. The cortisol response diminished progressively on subsequent exposures or sham exposures, and was attributable to mild stress associated with the experimental protocol.