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Interaction MechanismsA number of explanations have been proposed, and are being researched, to better understand the interaction mechanisms between Extremely Low Frequency (ELF) magnetic fields and living organisms. The most important are: Induced currents mechanism Induced currents mechanism A basic physical interaction mechanism of ELF magnetic fields and living organisms. It is well-established that external ELF magnetic fields induce electric fields and currents in biological tissues. The electric field induced within the body increases with the frequency of the external field and the size of the exposed body. Above a certain threshold level, these induced electric fields provoke a reaction from some specific cells. This threshold is well above typical human exposure levels. Typical exposure at home results in very small induced electric fields, while some exposure at work and exposure directly under very high-voltage power lines may be greater resulting in electric fields of about 1 mV/m in some tissues. Radical pair mechanism A suggested interaction mechanism between ELF magnetic fields and living organisms based on the effects of static (DC) magnetic fields on the rate of the chemical reactions that involve free radicals. A free radical is an atom or molecule that contains an unpaired electron in the outer shell, as a result of which it is highly reactive. Since these free-radicals have lifetimes in the microsecond range, and power-frequency fields have a cycle time in the millisecond range, a power-frequency field acts like a static field during the time scale in which these reactions occur. Static (DC) magnetic fields can affect the reaction rates of chemical reactions that involve free radical. However, one should consider the ELF field as a static field when single elementary chemical reactions are considered and then no detectable biological effect should be expected. In biochemical systems involving enzymes, sequences of elementary reactions can affect biological tissues, even at low field-strength but experimental evidence for the radical-pair mechanism in biological processes at field strengths below 500µT is still lacking. Ion charge-to-mass resonance mechanism This interaction mechanism, still under research, suggest that Extremely Low Frequency (ELF) magnetic fields, added to the Earth's static magnetic field, may affect the transfer of ions through cell membranes. We all are exposed to the inevitable Earth's geomagnetic field (a static field). When our cells are exposed to an alternating electric or magnetic field this exposure is thus superimposed on the Earth's static field (resonance). Experimental studies have shown that this may affect ion transfer through cell membranes. However, there is no definite experimental evidence and no accepted explanation at either the microscopic or molecular level of how such field combinations could be effective. Stochastic resonance mechanism This suggested interaction mechanism is based on the following phenomena: under certain circumstances, the addition of a small amount of input noise to a larger input signal can greatly increase the output signal and the output signal-to-noise ratio. The phenomena has been labeled "stochastic resonance" though the process does not involve ordinary resonance. Such stochastic-resonance enhancements have been observed in certain cells of cray fish. However, it is highly speculative to connect stochastic resonance to predict enhanced ELF electro magnetic field sensitivity in biological matter. Since the addition of a small input signal to a larger input noise does not result in an increased output signal-to-noise ratio, it would not seem that the stochastic resonance phenomena would enhance ELF electro magnetic field sensitivity in biological matter. Biogenic magnetite mechanism A suggested interaction mechanism between Extremely Low Frequency (ELF) magnetic fields and the particules of magnetite present in certain living organisms has been studied. Small magnetic particles (magnetite) have been found in many organisms (bacteria, honeybees, fish, birds, etc.) and even in the human brain. In animals they seem to play a role in their orientation towards the earth's static magnetic field. It was suggested that ELF-magnetic fields could directly act on such particles and that this could explain adverse biological effects. This would however require 50/60 Hz fields of more than 1 µT. Source & © based on the US Medical College of Wisconsin (US MCW) FAQ webpage on Power Lines and Cancer www.mcw.edu/gcrc/cop/powerlines-cancer-FAQ/toc.html#18C Related publication:
Other Figures & Tables on this publication: Magnetic Field Intensity Units |
