Chronic exposure of primates to 60‐Hz electric and magnetic fields: III. Neurophysiologic effects

The neurophysiologic effects of combined 60‐Hz electric (E) and magnetic (B) fields, of magnitudes comparable to those produced by high‐voltage powerlines, were investigated in 10 monkeys ( Macaca nemestrina ). Six animals (experimental group) were each exposed to three different levels of E and B fields: 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G. Field exposures were preceded and followed by sham exposures, during which factors of field generation were present (e.g., heat, vibration, noise, etc.) without E and B fields. Each of the five segments (i.e., the three exposure segments and the initial and final sham exposure segments) lasted 3 weeks. Animals were exposed for 18 h/day (fields on at 1600 h, off at 1000 h). Four other animals (external control group) were given sham exposure for the entire 15‐week period. Auditory, visual, and somatosensory evoked potentials were recorded twice a week, during the daily 6‐h field‐off period. E‐ and B‐field exposure had no effect on the early or mid‐latency evoked potential components, suggesting that exposure at these levels has no effect on peripheral or central sensory afferent pathways. However, there was a statistically significant decrease in the amplitudes of late components of the somatosensory evoked potential during the 10kV/m and 0.3 G, and 30 kV/m and 0.9 G exposure levels. This result is possibly related to the opiate antagonist effect of electromagnetic field exposure reported by others.