Effects of Weak High-Frequency Electromagnetic Fields on Biological Systems

Abstract

I examine the constraints on the biological effects of the interactions of radio-frequency and microwave radiation imposed by thermodynamic noise. An analysis of the interaction of radiation with small biological elements at the cellular level shows that at power densities of 10 mw/cm² (or 200 V/m), a level characteristic of occupational exposure limits, the interaction of electromagnetic fields with elements holding permanent charges or charge distributions will be masked by thermal noise and, hence, cannot be expected to generate biological effects.

However, I cannot exclude the possibility that energy transfers to large free cells (with radii greater than 20 μm) exceed kT.

Moreover, as pointed out by Schwan, the interactions of AC fields of 200 V/m with charges induced by the fields may generate energy transfers in cellular systems of the order of kT. I also examine the possible actions of enzymes as rectifiers, as suggested by Astumian, and show that AC fields of 200 V/m might drive molecular concentrations in cells away from equilibrium beyond that expected from noise drifts. Hence, the possibility of biological effects from such interactions is not, therefore, definitely excluded by thermodynamic considerations.

It is of practical interest that, for any interaction of electromagnetic fields at this power level, sharp resonances are excluded and biological effects, if they should exist, should not change radically over differences in frequency of a factor of two.