MICROWAVE-ABSORPTION BY MAGNETITE - A POSSIBLE MECHANISM FOR COUPLINGNONTHERMAL LEVELS OF RADIATION TO BIOLOGICAL-SYSTEMS

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) p rovide a physical mechanism through which microwave radiation might pr oduce or appear to produce biological effects. Magnetite is an excelle nt absorber of microwave radiation at frequencies between 0.5 and 10.0 GHz through the process of ferromagnetic resonance, where the magneti c vector of the incident field causes precession of Bohr magnetons aro und the internal demagnetizing field of the crystal. Energy absorbed b y this process is first transduced into acoustic vibrations at the mic rowave carrier frequency within the crystal lattice via the magnetoaco ustic effect; then, the energy should be dissipated in cellular struct ures in close proximity to the magnetite crystals. Several possible me thods for testing this hypothesis experimentally are discussed. Studie s of microwave dosimetry at the cellular level should consider effects of biogenic magnetite. (C) 1996 Wiley-Liss, Inc.