Microwave absorption by magnetite: A possible mechanism for coupling nonthermal levels of radiation to biological systems

Abstract

The presence of trace amounts of biogenic magnetite (Fe3O4) in animal and human tissues and the observation that ferromagnetic particles are ubiquitous in laboratory materials (including tissue culture media) provide a physical mechanism through which microwave radiation might produce or appear to produce biological effects. Magnetite is an excellent absorber of microwave radiation at frequencies between 0.5 and 10.0 GHz through the process of ferromagnetic resonance, where the magnetic vector of the incident field causes precession of Bohr magnetons around the internal demagnetizing field of the crystal. Energy absorbed by this process is first transduced into acoustic vibrations at the microwave carrier frequency within the crystal lattice via the magnetoacoustic effect; then, the energy should be dissipated in cellular structures in close proximity to the magnetite crystals. Several possible methods for testing this hypothesis experimentally are discussed. Studies of microwave dosimetry at the cellular level should consider effects of biogenic magnetite. © 1996 Wiley‐Liss, Inc.

Chemical magnetoreception in birds: The radical pair mechanism

“…This has been observed for reactions of organic radicals in solution when the frequency of the applied field matches a S 7 T interconversion frequency arising from hyperfine and/or Zeeman interactions (70)(71)(72). Such resonances are diagnostic for radical pairs: Magnetite particles of sufficient size to function as a compass are too large to reorient in magnetic fields fluctuating as rapidly as 1 MHz (73,74). Linearly polarized radio frequency fields 100 times weaker than the Earth's field (Ϸ500 nT), with frequencies of 7.0 MHz or 1.315 MHz, are sufficient to disrupt the migratory orientation of caged European robins (75,76).…”

Biogenic magnetite in the nematode Caenorhabditis elegans

“…In 1996, mechanisms based on magnetite transduction were proposed to explain potential mobile phone bioeffects (Dobson & St Pierre 1996;Kirschvink 1996). These mechanisms are now being tested experimentally, with interesting results (Cranfield et al 2003a,b).…”

H-Field Contribution to the Electromagnetic Energy Deposition in Tissues Similar to the Brain but Containing Ferrimagnetic Particles, During Use of Face-Held Radio Transceivers

“…Back in 1996, Kirschvink formulated a hypothesis on the mechanism of transduction of the nonthermal electromagnetic energy by magnetite and underlined the need of a cellular-level dosimetric investigation in the very proximity of magnetite crystals in the brain [7].…”