Documented negative effects too numerous to mention There is no correlation given with signal strength or modality used, i.e. audio-visual, EMF, magnetic, electrostatic, gravitic. Also, most ELF research is now Govt classified, particularly since the mid-1960's when Hamer discovered behavioral effects as the result of applied sinusoidal field gradients as low as 4 volts. [SS via DW]
50.0 - dominant frequency of polyphasic muscle activity, mains electrical in U.K. [EQ]; Slower cerebral rhythms [??]