Hypothetical biophysical mechanisms for the action of weak low frequency electromagnetic fields at the cellular level

Power-line frequency electric fields of 1 mV.m(-1) in the body can be induced by external electric fields of 10 kV.m(-1) and by magnetic fields of 50 mu T through the Faraday effect. Constraints from physical principles show that such internal fields are unlikely to generate any biological effects and fields less than 0.1mV.m(-1) must be ineffective. Moderately strong power line frequency magnetic fields may affect biology through the direct interaction of the fields with the magnetic moments of ferrimagnetic materials in the body and through effects on radical pair recombination as a consequence of the interaction of the fields with electron magnetic moments. However, magnetic fields smaller than 50 mu T (500 mG) are unlikely to affect biology, and fields less than 5 mu T cannot do so. Ion Cyclotron Resonance and Ion Parametric Resonance models of biological effects of the interaction of power-line frequency magnetic fields with the magnetic moments of ions are not in accord with fundamental physical principles.