Evaluation of Human Exposure to Low Frequency Fields
SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TX
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The Biophysical model concept described in this paper might be suited as a basis of discussion to determine and define limits of exposure to electric or magnetic fields below 100 kHz, including 5060 Hz. The electric field strength within the tissue in the environment of excitable neurons and muscle cells is considered decisive for the biological effects are compiled from experimental and theoretical studies. On the basis of these data it is possible to establish safe, dangerous, and hazardous current density curves as a function of frequency. The criterion for the definition of injury is the elicitation of ventricular fibrillation which must be avoided. To define exposure limits, the field strength or current density causing injury should be reduced by a factor of 300. The arguments supporting this wide safety margin are discussed. In the second part of this paper the electric and magnetic field strength in the human environment is correlated with the corresponding electric current density induced in the human body. This enables safe, dangerous, and hazardous levels of current density in the human body to be correlated with the external electric or magnetic field intensity. Parts of the concept presented in this paper have been adopted in the DINEDE Regulation No. 0848 which defines the limits for frequencies above 10 kHZ.
- Electricity and Magnetism