Effect of a low intensity magnetic field on human motor behavior

Extremely low frequency (ELF) magnetic fields (MF) are omnipresent in our modern daily environment, but their effects on humans are still not clearly established. The aim of this study was to determine the effect of a 50 Hz, 1,000 microT MF centered at the level of the head on human index finger micro-displacements. Twenty-four men recruited among the personnel of the French company, Electricité de France (EDF), completed the experiment. Their postural and kinetic tremors were recorded under four "field-on" and four "field-off" conditions, each tested during a real and a sham sequence. Eight postural and four kinetic tremor characteristics were calculated on recorded time series and were used for statistical analysis. No effect of the MF was found for kinetic tremor. Concerning postural tremor, the proportion of oscillations at low frequencies (between 2 and 4 Hz) was higher during the real than during the sham exposure sequence (P<.05). It suggests that MF could have a subtle delayed effect on human behavior, which is clearly not pathological. These results should be taken into account for the establishment of new exposure limits.