Effects of Weak High-Frequency Electromagnetic Fields on Biological Systems
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.
KeywordsExternal Field Thermal Noise Electric Dipole Moment Magnetic Dipole Moment Thermal Relaxation Time
Unable to display preview. Download preview PDF.
- 1.R. K. Adair, Constraints on biological effects of weak extremely-low-frequency electromagnetic fields, Phys. Rev. A43:1039 (1991).Google Scholar
- 4.M. M. Walker and M. E. Bitterman, Conditioned responding to magnetic fields by honeybees, J. Comp. Physiol. A157:157 (1985).Google Scholar
- 5.These standard techniques are described in, J. B. Marion and M. A. Heald. “Classical Electromagnetic Radiation,” Harcourt Brace Jovanovich, New York (1980).Google Scholar
- 6.W. Grundler and F. Kaiser, Nanobiology 1:162 (1992).Google Scholar
- 8.H. P. Schwan, EM-field induced force effects, in “Interactions between Electromagnetic fields and cells,” Editors, A. Chiabrera, C. Nicolini, and H. P. Schwan, Plenum Publishing Corp. (1985).Google Scholar
- 12.K. Foster and H. Schwan, Dielectric properties of tissues, “CMC Handbook of Biological Effects of Electromagnetic Systems,” Editors, C. Polk and E. Postow, CMC Press, Boca Raton, Florida (1985).Google Scholar
- 13.H. P. Schwan, Interactions of ELF fields with excitable tissues, and Biophysical principles of the interaction of ELF fields with living matter, II coupling considerations and forces, “Biological Effects and Dosimetry of Static and, EMF Electromagnetic Fields,” Editors, M. Grandolfo, S. M. Michaelson and A. Rindl, Plenum Publishing Corp. (1985).Google Scholar
- 15.J. C. Lin, Computer methods for field intensity predictions, “CMC Handbook of Biological Effects of Electromagnetic Fields,” Editors, C. Polk and E. Postow, CMC Press, Boca Raton (1986).Google Scholar
- 17.F. S. Barnes, Extremely low-frequency (ELF) and very low-frequency electric fields; rectification, frequency sensitivity, noise, and related phenomena, “CMC Handbook Biological Effects of of Electromagnetic Fields,” Editors, C. Polk and E. Postow, CMC Press, Boca Raton (1986).Google Scholar