Evaluation of Biological Effects, Dosimetric Models, and Exposure Assessment Related to ELF Electric- and Magnetic-Field Guidelines

Abstract

Several organizations worldwide have issued guidelines to limit occupational and public exposure to electric and magnetic fields and contact currents in the extremely low frequency range (<3 kilohertz). In this paper, we evaluate relevant developments in biological and health research, computational methods for estimating dosimetric quantities, and exposure assessment, all with an emphasis on the power frequency (60 hertz in North America, 50 hertz in Europe). The aim of each guideline is to prevent acute neural effects of induced electric fields. An evaluation of epidemiological and laboratory studies of neurobiological effects identified peripheral nerve stimulation as the response most suitable for establishing a magnetic-field guideline. Key endpoints that merit further study include reversal of evoked potentials; cardiovascular function, as measured by heart rate and heart rate variability; and sleep patterns. High-resolution computations of induced electric fields and current densities in anatomically correct human models are now achieved with finite-difference methods. The validity and limitations of these models have been demonstrated by computations in regular geometric shapes, using both analytic and numeric computations. Calculated values for average dosimetric quantities are typically within a few percent for the two approaches. However, maximum induced quantities are considerably overestimated by numerical methods, particularly at air interfaces. Overestimates are less pronounced for the upper 99th percentile level of a dosimetric quantity, making this measure a more useful indicator of maximum dose. Neural stimulation thresholds are dependent on the electric field around the excitable cell rather than on the current density, making the former preferable for expression of basic restrictions based on nervous system function. Furthermore, modeling data indicate that the induced electric field is much less strongly influenced by tissue conductivity than is the induced current density. In the electric utility industry, most magnetic-field exposures at or near guideline levels occur in highly nonuniform fields. Two methods are described for simplified estimation of induced quantities in such fields, with each method using as input modeling results for uniform field exposure. These methods have practical value for assessing occupational exposures relative to guideline levels.

The cardiovascular response to an acute 1800-μT, 60-Hz magnetic field exposure in humans

“…One hypothesis is that the fields may cause induced electrical current changes in the autonomic central nervous system control of cardiac rhythm (Kavet et al 2001;Repacholi and Greenebaum 1999), perhaps by interacting with pacemaker control, as dosimetry studies have argued that direct cardiac tissue stimulation is unlikely (Hart and Gandhi 1998). However, other biological interaction mechanism theories have been proposed, including direct tissue stimulation through induced currents of sufficient strength , cellular level Ca 2?…”

Effects of extremely low frequency electromagnetic field (ELF-EMF) on catalase, cytochrome P450 and nitric oxide synthase in erythro-leukemic cells

“…The biological effects in cell lines exposed to ELF-EMFs have been frequently noted [19,24,35,33,42]. However, despite the large number of studies, an understanding is still lacking [12,25,46]. The time span of application is an important factor which governs the physiological response of cells towards ELF-EMF exposure.…”

On the Method of Investigating Human Exposure to Nonuniform Magnetic Field

“…From this point of view, relevant evaluation methods have been proposed by researchers [13][14][15][16][17][18] and standardization bodies such as the IEC (International Electrotechnical Commission) [19][20][21]. From this point of view, relevant evaluation methods have been proposed by researchers [13][14][15][16][17][18] and standardization bodies such as the IEC (International Electrotechnical Commission) [19][20][21].…”