Some studies suggest effects of 50 Hz magnetic field exposure on brain activity and nociception, which should be verified. Since cardiovascular regulation is functionally related to pain modulation, some relevant cardiovascular parameters were measured additionally.
40 healthy male subjects participated in the study. Subjects were randomly assigned to one of the two exposure intensity groups (n=20 each; however, only data from 10 subjects from group 1 and 15 subjects from group 2 were analyzed): 1) 40 µT magnetic field and 2) 80 µT magnetic field. Each volunteer was investigated during two sessions at an interval of 1-2 weeks: one exposure session and one sham exposure session. Exposure and sham exposure were conducted in a random order (cross-over study).
|Chamber||subject was comfortably seated in a quiet room|
|Setup||2 circular coils, similar to Helmholtz coils (44 cm in diameter, each composed of an aluminum ring on which 50 copper coils [0.8 mm diameter] were winded), produced the magnetic field; the coils were positioned around the head of the subject with the head at the center of the coils; the subject was invited to read a magazine during exposure|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||40 µT||peak value||measured||-||-|
|magnetic flux density||80 µT||peak value||measured||-||-|
Brain activity in the alpha wave band was significantly increased after exposure to the 80 µT magnetic field (group 2) compared to the sham exposure.
The pain threshold was significantly lower after exposure to the 40 µT magnetic field (group 1) compared to the sham exposure.
No differences were found in blood pressure, heart rate and hormonal blood levels between exposure and sham exposure in both groups.
The authors conclude, that exposure of subjects to a 50 Hz magnetic field might affect the alpha wave brain activity and nociception, though it is uncertain whether both effects are linked.