During the past 10 years, the ferromagnetic mineral magnetite (Fe3O4) has been found as a biochemical precipitate in organisms ranging from bacteria through higher vertebrates. Particles of magnetite are fundamentally different than any other form of iron present in living systems because they are permanently magnetized and interact over 1,000,000 times more strongly with external magnetic fields than do other biogenic iron compounds. With the use of superconducting moment magnetometers, studies of tissue from evolutionarily separate groups of vertebrates, including reptiles, cetaceans, and primates, have revealed the presence of ferromagnetic material in anatomically similar structures, including the dura, midbrain and cerebellum. Support is requested in this proposal to examine human tissue for the presence of ferromagnetic particles, and, if they are present, to extract them, determine their mineralogy, composition, crystal form, and particle sizes. In addition to providing knowledge concerning the evolution of magnetite biomineralization, these studies will provide important information for several areas of biomedical research. For studies of evoked magnetic fields, a knowledge of the abundance and distribution of ferromagnetic material within the human head will enable estimates to be made concerning the magnitude of any ferromagnetic contribution to the external magnetic signals. Second, the presence of magnetite within the brain may offer an additional explanation for the ability of Magnetic Resonance Imaging (MRI) techniques to map out the density of histologic iron, and may lead to a better ability to interpret these MRI signals. Finally, these data also will permit a series of biophysical calculations to be made concerning possible side effects of human exposure to strong magnetic fields; all past estimates of the biological effects and physical safety aspects of MRI imaging and in vivo spectroscopy, for example, have failed to consider presence of such highly magnetic material. These latter concerns are enhanced by the recent discovery of liquid-nitrogen temperature superconductors- these materials may lead to a wider use of MRI imaging in medicine and a wider exposure of humans to strong magnetic fields.
