International workshop “effects of static magnetic fields relevant to human health”: Rapporteurs report: dosimetry and volunteer studies

Abstract

The presentations in this session focussed on effects in humans. Both experimental results and model calculations were presented. Dr Donald W. Chakeres, Ohio State University, Columbus OH, USA, presented the results of exposure of volunteers to strong static fields (Chakeres et al., 2003a, b). One group was exposed to incremental field strengths by introducing them in the magnet using discrete steps. At maximum exposure the head was exposed to approximately 8T, while the maximum field strength in the heart region was approximately 7T. At each exposure level heart rate, blood pressure, blood oxygenation, core temperature, ECG, and respiratory rate were measured. No effects were seen, except for a tendency for blood pressure to increase and an alteration in the ECG. The latter can explained by small changes in aortic blood flow due to coupling in the direction of the aortic arch (but not to the descending part of the aorta). The blood pressure variations were smaller than the differences due to changing from supine to upright position. A second group of healthy volunteers was tested at 8 and 0.05T (outside the magnet) using 12 standardized neuropsychological tests and by comparing auditory reaction times. Small changes were noted for the most demanding tests, but no adverse effects were seen. For 9 out of 12 measures the subjects did better at 8 T. Several subjects complained about metallic taste, dizziness, nystagmus and discomfort due to the use of the head coil. These complaints vanished immediately after removal from the magnet. At follow-up 3 months later no symptoms were reported.