The brain effects of occupational strength 50 Hz magnetic field

Human cognitive behavioural and neurophysiological effects during exposure to extremely low frequency (ELF) 50 Hz magnetic field (MF) of 28.4 /spl mu/T were measured triple-blinded. Forty subjects were exposed to MF and sham in two visits in counterbalanced orders. The visits were scheduled after two training sessions and one baseline session. Two of the 29 parameters assessed were inter-peak latencies of visual evoked response (VER) and auditory evoked response (AER). The other 27 variables were measures of the brain performance, reaction time (RT), learning, memory (spatial, short-term, long-term, working and secondary), storage and retrieval of information (numerical, verbal and pictorial), accuracy, errors, attention, alertness and vigilance. The conclusion was a small decline in the human brain performance and in particular statistically significant deterioration in choice reaction time accuracy (p=0.03), word recognition accuracy (p=0.03) and numerical working memory (p=0.05). This study found no effect in grouped measures of alertness. No adjustment for multiple comparisons has been made, and as such, with 29 outcome variables, the authors acknowledge that any statistically significant result at a 5% level may be due solely to chance.