next up previous
Next: Other exposure standardsand Up: Discussion Previous: Comparison of Articulograph and

Comparison to typical ELF fields

Some household appliances may produce 60Hz fields with the same flux density as the fields of the Articulograph, but because of the difference in frequency of the transmitted fields, the effects are not comparable.

As noted in section 1, the current induced by a magnetic field increases with frequency, so the current produced by a 20kHz field at 35uT is much stronger than that produced by a 60Hz field at 35uT. As noted in section 2, the threshold for stimulation of excitable cells also increases with frequency, so that neither a 35uT 20kHz field nor a 35T 60Hz field will stimulate biologically excitable cells, despite the greater induced current density of the VLF field.

Finally, ELF fields below the threshold of cell stimulation have been linked to other biological effects, while VLF fields have not been linked to any such effects.

Mark Hasegawa-Johnson
Mon May 26 15:33:40 PDT 1997