Comparison of coupling of humans to electric and magnetic fields with frequencies between 100 Hz and 100 kHz

Recent laboratory and epidemiological results have stimulated interest in the hypothesis that human beings may exhibit biological responses to magnetic and/or electric field transients with frequencies in the range between 100 Hz and 100 kHz. Much can be learned about the response of a system to a transient stimulation by understanding its response to sinusoidal disturbances over the entire frequency range of interest. Thus, the main effort of this paper was to compare the strengths of the electric fields induced in homogeneous ellipsoidal models by uniform 100 Hz through 100 kHz electric and magnetic fields. Over this frequency range, external electric fields of about 25–2000 V/m (depending primarily on the orientation of the body relative to the field) are required to induce electric fields inside models of adults and children that are similar in strength to those induced by an external 1 μT magnetic field. Additional analysis indicates that electric fields induced by uniform external electric and magnetic fields and by the nonuniform electric and magnetic fields produced by idealized point sources will not differ by more than a factor of two until the sources are brought close to the body. Published data on electric and magnetic field transients in residential environments indicate that, for most field orientations, the magnetic component will induce stronger electric fields inside adults and children than the electric component. This conclusion is also true for the currents induced in humans by typical levels of 60 Hz electric and magnetic fields in U.S. residences. Bioelectromagnetics 18:67–76, 1997. © 1997 Wiley-Liss, Inc.     

Exposure of welders and other metal workers to ELF magnetic fields

This study assessed exposure to extremely low frequency (ELF) magnetic fields of welders and other metal workers and compared exposure from different welding processes. Exposure to ELF magnetic fields was measured for 50 workers selected from a nationwide cohort of metal workers and 15 nonrandomly selected full-time welders in a shipyard. The measurements were carried out with personal exposure meters during 3 days of work for the metal workers and 1 day of work for the shipyard welders. To record a large dynamic range of ELF magnetic field values, the measurements were carried out with “high/low” pairs of personal exposure meters. Additional measurements of static magnetic fields at fixed positions close to welding installations were done with a Hall-effect fluxmeter. The total time of measurement was 1273 hours. The metal workers reported welding activity for 5.8% of the time, and the median of the work-period mean exposure to ELF magnetic fields was 0.18 μT. DC metal inert or active gas welding (MIG/MAG) was used 80% of the time for welding, and AC manual metal arc welding (MMA) was used 10% of the time. The shipyard welders reported welding activity for 56% of the time, and the median and maximum of the workday mean exposure to ELF magnetic fields was 4.70 and 27.5 μT, respectively. For full-shift welders the average workday mean was 21.2 μT for MMA welders and 2.3 μT for MIG/MAG welders. The average exposure during the effective time of welding was estimated to be 65 μT for the MMA welding process and 7 μT for the MIG/MAG welding process. The time of exposure above 1 μT was found to be a useful measure of the effective time of welding. Large differences in exposure to ELF magnetic fields were found between different groups of welders, depending on the welding process and effective time of welding. MMA (AC) welding caused roughly 10 times higher exposure to ELF magnetic fields compared with MIG/MAG (DC) welding. The measurements of static fields suggest that the combined exposure to static and ELF fields of MIG/MAG (DC) welders and the exposure to ELF fields of MMA (AC) welders are roughly of the same level. Bioelectromagnetics 18:470–477, 1997. © 1997 Wiley-Liss, Inc.     

What is the time scale of magnetic field interaction in biological systems?

An experimental test constraining the intrinsic time scale of a primary physical mechanism that detects extremely-low-frequency (ELF) magnetic fields in biological systems is proposed. The suggested test postulates that a transductive mechanism operating on time scales much shorter than the period of an applied magnetic field cannot obtain any information about the exposure conditions other than the absolute magnitude of the field. By generating field exposures that differ in their vector properties but are equivalent in their time-varying absolute amplitude, it is possible to differentiate between two broad classes of mechanisms: 1) those with intrinsic time scales comparable with or longer than those of the external influence, and 2) those that are much faster than the period of the applied field. The hypothesis assumes an experimental model proven to respond to magnetic fields and sensitive to a change of about a factor of two in one of the field parameters (AC, DC amplitude or frequency). The case of general linearly polarized fields is discussed, and an analytical solution for the case of perpendicular AC/DC fields is given. Bioelectromagnetics 18:244–249, 1997 © 1997 Wiley-Liss, Inc.     

Effects of low-intensity AC and/or DC electromagnetic fields on cell attachment and induction of apoptosis

Rat tendon fibroblast (RTF) and rat bone marrow (RBM) osteoprogenitor cells were cultured and exposed to AC and/or DC magnetic fields in a triaxial Helmholtz coil in an incubator for up to 13 days. The AC fields were at 60 and 1000 Hz and up to 0.25 mT peak to peak, and the DC fields were up to 0.25 mT. At various combinations of field strengths and frequencies, AC and/or DC fields resulted in extensive detachment of preattached cells and prevented the normal attachment of cells not previously attached to substrates. In addition, the fields resulted in altered cell morphologies. When RTF and RBM cells were removed from the fields after several days of exposure, they partially reattached and assumed more normal morphologies. An additional set of experiments described in the Appendix corroborates these findings and also shows that low-frequency EMF also initiates apoptosis, i.e., programmed cell death, at the onset of cell detachment. Taken together, these results suggest that the electromagnetic fields result in significant alterations in cell metabolism and cytoskeleton structure. Further work is required to determine the relative effect of the electric and magnetic fields on these phenomena. The research has implications for understanding the role of fields in affecting bone healing in fracture nonunions, in cell detachment in cancer metastasis, and in the effect of EMF on organisms generally. Bioelectromagnetics 18:264–272, 1997. © Wiley-Liss, Inc.     

Electromagnetic fields in medicine – The state of art

ABSTRACT

Introduction: Intense development of methods belonging to physical medicine has been noted recently. There are treatment methods, which in many cases lead to reduction treatment time and positively influence on quality of life treatment patients. Research implications: The present physical medicine systematically extends their therapeutic possibilities. This above applies to illnesses and injuries of locomotor system, diseases affecting of soft tissues, as well as chronic wounds. The aim of the study: The evidence on this are the results of basic and clinical examinations relating the practical use of electromagnetic fields in medicine. Originality: In this work the authors introduced the procedure using the current knowledge relating to physical characteristic and biological effects of the magnetic fields. In the work the following methods were used: static magnetic fields, spatial magnetic fields, the variable magnetic fields both with laser therapy (magnetolaserotherapy) and variable magnetic fields both with light optical non-laser (magnetoledtherapy) talked.     

Oviposition and development of Drosophila modified by magnetic fields

Drosophila flies placed in a habitat with two lateral boxes demonstrated sensitivity to magnetic fields: Oviposition decreased by exposure to pulsated extremely low frequency (ELF) (100)Hz, 1.76 miliTesla (mT) and sinusosidal fields (50 Hz, 1 mT), while there was no initial effect of exposure to a static magnetic field (4.5 mT). Drosophila eggs treated for 48 h with the above described fields showed that (1) mortality of eggs was lower in controls than in eggs exposed to all tested magnetic fields; (2) mortality of larvae increased when a permanent magnet was used; (3) mortality of pupae was highest when a permanent magnet was used; and (4) general adult viability was highest in controls (67%) and diminished progressively when eggs were exposed to pulsated (55%), sinusoidal (45%), and static (35%) magnetic fields.     

Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian Dugesia tigrina

We recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. We report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 μT. These anomalies often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 μV/m. The addition of either 51.1 or 78.4 μT DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas our previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling. These results together with those reported previously point to two distinct physiological effects produced in regenerating planaria by exposure to weak extremely-low-frequency (ELF) magnetic fields. They further suggest that the planarian, which has recently been identified elsewhere as an excellent system for use in teratogenic investigations involving chemical teratogens, might be used similarly in teratogenic investigations involving ELF magnetic fields. © 1996 Wiley-Liss, Inc.     

Comparison of cardiac and 60 Hz magnetically induced electric fields measured in anesthetized rats

Extremely low frequency magnetic fields interact with an animal by inducing internal electric fields, which are in addition to the normal endogenous fields present in living animals. Male rats weighing about 560 g each were anesthetized with ketamine and xylazine. Small incisions were made in the ventral body wall at the chest and upper abdomen to position a miniature probe for measuring internal electric fields. The calibration constant for the probe size was 5.7 mm, with a flat response from at least 12 Hz to 20 kHz. A cardiac signal, similar to the normal electrocardiogram with a heart rate of about 250 bpm, was readily obtained at the chest. Upon analysis of its spectrum, the cardiac field detected by the probe had a broad maximum at 32–95 Hz. When the rats were exposed to a 1 mT, 60 Hz magnetic field, a spike appeared in the spectrum at 60 Hz. The peak-to-peak magnitudes of electric fields associated with normal heart function were comparable to fields induced by a 1 mT magnetic field at 60 Hz for those positions measured on the body surface (where induced fields were maximal). Within the body, or in different directions relative to the applied field, the induced fields were reduced (reaching zero at the center of the animal). The cardiac field increased near the heart, becoming much larger than the induced field. Thus, the cardiac electric field, together with the other endogenous fields, combine with induced electric fields and help to provide reference levels for the induced-field dosimetry of ELF magnetic field exposures of living animals. Bioelectromagnetics 18:317–323, 1997. © 1997 Wiley-Liss, Inc.     

Effects of combined DC and AC magnetic fields on germination of hornwort seeds

Seeds of hornwort (Cryptotaenia japonica Hassk) were exposed to sinusoidally time-varying extremely low frequency (ELF) magnetic fields (AC fields) in combination with the local geomagnetic field (DC field). Exposure lasted 24 h/day for 16 days. Three directions of the AC magnetic fields were considered; the vertical (magnetic flux density B ACV, the directions parallel B ACparallel), and perpendicular B ACperpendicular to the direction of total geomagnetic field (magnetic flux density BG) in the geomagnetic plane (GP). Controls consisted of seeds exposed to zero AC magnetic fields in combination with the DC magnetic field. The B ACV in combination with BG effectively promoted the germination of hornwort seeds when applied at 750 microT (RMS) at 7 Hz or 500 microT (RMS) at 14 Hz from among the cases of individual frequencies f = 3.5, 7.0, 10.5, 14.0 Hz at 500 and 750 microT. The B ACparallel promoted the germination of hornwort seeds more effectively than the B ACperpendicular in combination with BG when 500 and 750 microT at 7 Hz were applied.     

Extremely-Low Frequency Magnetic Field Effects on Sulfate Reducing Bacteria Viability

50?Hz magnetic fields effects on Sulfate Reducing Bacteria (SRB) viability were studied by colony forming units (CFU) counting. We found a 15% decrease of CFU number after magnetic field exposure (B=7.1?mT, f=50?Hz, t=24?min) compared to the control samples. These results are in good agreement with our previous work on other bacterial strains. The magnetic field effects on SRB are relatively large for small magnetic fields. The data correlations have been subjected to a simple physical chemical analysis, yielding surprisingly large estimates for the characteristic magnetic reaction susceptibility, even when the entire bacterium is assumed to be the direct target of interaction of the magnetic ac fields for the exposures in the time range from 3–24?min.     

Magnetic fields suppress Pseudomonas aeruginosa biofilms and enhance ciprofloxacin activity

Due to the refractory nature of pathogenic microbial biofilms, innovative biofilm eradication strategies are constantly being sought. Thus, this study addresses a novel approach to eradicate Pseudomonas aeruginosa biofilms. Magnetic nanoparticles (MNP), ciprofloxacin (Cipro), and magnetic fields were systematically evaluated in vitro for their relative anti-biofilm contributions. Twenty-four-hour biofilms exposed to aerosolized MNPs, Cipro, or a combination of both, were assessed in the presence or absence of magnetic fields (Static one-sided, Static switched, Oscillating, Static + oscillating) using changes in bacterial metabolism, biofilm biomass, and biofilm imaging. The biofilms exposed to magnetic fields alone exhibited significant metabolic and biomass reductions (p < 0.05). When biofilms were treated with a MNP/Cipro combination, the most significant metabolic and biomass reductions were observed when exposed to static switched magnetic fields (p < 0.05). The exposure of P. aeruginosa biofilms to a static switched magnetic field alone, or co-administration with MNP/Cipro/MNP + Cipro appears to be a promising approach to eradicate biofilms of this bacterium.     

Clarification and application of an ion parametric resonance model for magnetic field interactions with biological systems

Theoretical models proposed to date have been unable to clearly predict biological results from exposure to low-intensity electric and magnetic fields (EMF). Recently a predictive ionic resonance model was proposed by Lednev, based on an earlier atomic spectroscopy theory described by Podgoretskii and Podgoretskii and Khrustalev. The ion parametric resonance (IPR) model developed in this paper corrects mathematical errors in the earlier Lednev model and extends that model to give explicit predictions of biological responses to parallel AC and DC magnetic fields caused by field-induced changes in combinations of ions within the biological system. Distinct response forms predicted by the IPR model depend explicitly on the experimentally controlled variables: magnetic flux densities of the AC and DC magnetic fields (B_ac and B_dc, respectively); AC frequency (f_ac); and, implicitly, charge to mass ratio of target ions. After clarifying the IPR model and extending it to combinations of different resonant ions, this paper proposes a basic set of experiments to test the IPR model directly which do not rely on the choice of a particular specimen or endpoint. While the fundamental bases of the model are supported by a variety of other studies, the IPR model is necessarily heuristic when applied to biological systems, because it is based on the premise that the magnitude and form of magnetic field interactions with unhydrated resonant ions in critical biological structures alter ion-associated biological activities that may in turn be correlated with observable effects in living systems. © 1994 Wiley-Liss, Inc.     

Design and fabrication of well confined uniform magnetic field exposure systems

Exposure systems that provide good magnetic field uniformity, minimum stray fields, and minimal heating, vibration, and hum, as well as capability for true sham exposure in which current flows in the coils, are needed to determine rigorously the biological effects of weak magnetic fields. Designs based on acrylic polymer coil support structures and twisted pair bifilary coil windings were employed to fabricate several different systems for the exposure of laboratory animals and cell cultures to magnetic fields. These systems exhibit excellent performance characteristics in terms of exposure field uniformity, stray field containment, and exposure field cancellation in the sham exposure mode. A custom-written computer program was used to determine the best arrangement for coils with regard to field uniformity in the exposure volume and stray field containment. For in vivo exposures, modules were made up of four Merritt four-coil sets, built into a single structure and positioned to form an octapole with fields directed in the horizontal plane. For in vitro applications, two different coil configurations were selected to produce the vertical fields required. A quadrupole system, comprising modules consisting of two Merritt four-coil sets arranged side by side to limit stray fields, was built as a prototype. In the second configuration, one Merritt four-coil set was positioned inside the other to form a concentric coil set. In both in vitro systems, exposure chambers were connected to remote commercial incubators in order to reduce ambient magnetic fields in the exposure volume. An active field cancellation circuit was developed for reducing ambient AC magnetic fields in the in vitro sham exposure chamber, when necessary. These design and fabrication approaches provide systems that offer uniform field exposures and excellent stray field containment when needed and are portable, washable, and relatively inexpensive. © 1994 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Empirical test of an ion parametric resonance model for magnetic field interactions with PC-12 cells

A companion paper describes a predictive ion parametric resonance (IPR) model of magnetic field interactions with biological systems based on a selective relation between the ratio of the flux density of the static magnetic field to the AC magnetic field and the charge-to-mass ratio of ions of biological relevance. Previous studies demonstrated that nerve growth factor (NGF)-stimulated neurite outgrowth (NO) in PC-12 cells can be inhibited by exposure to magnetic fields as a function of either magnetic field flux density or AC magnetic field frequency. The present work examines whether the PC-12 cell response to magnetic fields is consistent with the quasiperiodic, resonance-based predictions of the IPR model. We tested changes in each of the experimentally controllable variables [flux densities of the parallel components of the AC magnetic field (B_ac) and the static magnetic field (B_dc) and the frequency of the AC magnetic field] over a range of exposure conditions sufficient to determine whether the IPR model is applicable. A multiple-coil exposure system independently controlled each of these critical quantities. The perpendicular static magnetic field was controlled to less than 2 mG for all tests. The first set of tests examined the NO response in cells exposed to 45 Hz B_ac from 77 to 468 mG(rms) at a B_dc of 366 mG. Next, we examined an off-resonance condition using 20 mG B_dc with a 45 Hz AC field across a range of B_ac between 7.9 and 21 mG(rms). Finally, we changed the AC frequency to 25 Hz, with a corresponding change in B_dc to 203 mG (to tune for the same set of ions as in the first test) and a B_ac range from 78 to 181 mG(rms). In all cases the observed responses were consistent with predictions of the IPR model. These experimental results are the first to support in detail the validity of the fundamental relationships embodied in the IPR model. © 1994 Wiley-Liss, Inc.     

Effects of ELF magnetic fields on biological magnetite

The effects of 60 Hz magnetic fields of 5 μT (50 mG) or less on biological structures holding magnetite (Fe₃O₄) are shown to be much smaller than that from thermal agitation; hence such interactions cannot be expected to be biologically significant. © 1993 Wiley-Liss, Inc.     

Frequency-dependent interference by magnetic fields of nerve growth factor-induced neurite outgrowth in PC-12 cells

We have shown that 50 Hz sinusoidal magnetic fields within the 5-10 micro Tesla (μT) rms range cause an intensity-dependent reduction in nerve growth factor (NGF) stimulation of neurite outgrowth (NO) in PC-12 cells. Here we report on the frequency dependence of this response over the 15-70 Hz range at 5 Hz intervals. Primed PC-12 cells were plated in collagen-coated, 60 mm plastic petri dishes with or without 5 ng/ml NGF and were exposed to sinusoidal magnetic fields for 22 h in a CO₂ incubator at 37 °C. One 1,000-turn coil, 20 cm in diameter, generated vertically oriented magnetic fields. The dishes were stacked on the center axis of the coil to provide a range of intensities between 3.5 and 9.0 μT rms. The flux density of the ambient DC magnetic field was 37 μT vertical and 19 μT horizontal. The assay consisted of counting over 100 cells in the central portion (radius ≤0.3 cm) of each dish and scoring cells positive for NO. Sham exposure of cells treated identically with NGF demonstrated no difference in the percentage of cells with NO between exposed and magnetically shielded locations within the incubator. Analysis of variance demonstrated flux density-dependent reductions in NGF-stimulated NO over the 35-70 Hz frequency range, whereas frequencies between 15 Hz and 30 Hz produced no obvious reduction. The results also demonstrated a relative maximal sensitivity of cells at 40 Hz with a possible additional sensitivity region at or above 70 Hz. These findings suggest a biological influence of perpendicular AC/DC magnetic fields different from those identified by the ion parametric resonance model, which uses strictly parallel AC/DC fields. © 1995 Wiley-Liss, Inc.     

Environmental magnetic fields inhibit the antiproliferative action of tamoxifen and melatonin in a human breast cancer cell line

We have previously reported that environmental-level magnetic fields (1.2 μT [12 milligauss], 60 Hz) block the growth inhibition of the hormone melatonin (10⁻⁹ M) on MCF-7 human breast cancer cells in vitro. We now report that the same 1.2 μT, 60 Hz magnetic fields significantly block the growth inhibitory action of pharmacological levels of tamoxifen (10⁻⁷ M). In biophysical studies we have taken advantage of Faraday's Law of Current Induction and tested whether the 1.2 μT magnetic field or the associated induced electric field is responsible for this field effect on melatonin and tamoxifen. We observe that the magnetic field component is associated with the field blocking effect on melatonin and tamoxifen function. To our knowledge the tamoxifen studies represent the first experimental evidence for an environmental-level magnetic field modification of drug interaction with human breast cancer cells. Together, these findings provide support to the theory that environmental-level magnetic fields can act to modify the action of a drug or hormone on regulation of cell proliferation. Melatonin and tamoxifen may act through different biological pathways to down-regulate cell growth, and further studies are required to identify a specific biological site of interaction for the 1.2 μT magnetic field. Bioelectromagnetics 18:555–562, 1997. Published 1997 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Influence of 50-Hz magnetic fields and ionizing radiation on c-jun and c-fos oncoproteins

The effect of magnetic fields (50 Hz, 100 μT_rms sinusoidal magnetic field combined with a 55 μT geomagnetic-like field) and/or gamma rays of 60 Cobalt on the expression of the c-jun and c-fos proteins was investigated in primary rat tracheal epithelial cells and two related immortalized cell lines. Quite similar patterns and amplitudes of induction of these proteins were evidenced after either ionizing radiation or magnetic field exposure. No synergism after both treatments was observed. These findings suggest that magnetic fields explored in the present study may be considered as an insult at the cellular level. Bioelectromagnetics 19: 112–116, 1998. © 1998 Wiley-Liss, Inc.     

A Lorentz model for weak magnetic field bioeffects: Part II—Secondary transduction mechanisms and measures of reactivity

In Part I it was shown that the thermal component of the motion of a charged particle in an oscillator potential, that is, within a molecular binding site, rotates at the Larmor frequency in an applied magnetic field. It was also shown that the Larmor angular frequency is independent of the thermal noise strength and thus offers a mechanism for the biological detection of weak (µT‐range) magnetic fields. Part II addresses the question of how the Larmor trajectory could affect biological reactivity. The projection of the motion onto a Cartesian axis measures the nonuniformity of the Larmor trajectory in AC and combined AC/DC magnetic fields, suggesting a means of assessing resonances. A physically meaningful measure of reactivity based upon the classical oscillator trajectory is suggested, and the problem of initial conditions is addressed through averaging over AC phases. AC resonance frequencies occur at the Larmor frequency and at other frequencies, and are dependent upon the ratio of AC/DC amplitudes and target kinetics via binding lifetime. The model is compared with experimental data reported for a test of the ion parametric resonance (IPR) model on data from Ca²⁺ flux in membrane vesicles, neurite outgrowth from PC‐12 cells and a cell‐free calmodulin‐dependent myosin phosphorylation system, and suggests Mg²⁺ is the target for these systems. The results do not require multiple‐ion targets, selection of isotopes, or additional curve fitting. The sole fitting parameter is the binding lifetime of the target system and the results shown are consistent with the literature on binding kinetics. Bioelectromagnetics 30:476–488, 2009. © 2009 Wiley‐Liss, Inc.     

No short-term effects of high-frequency electromagnetic fields on the mammalian pineal gland

There is ample experimental evidence that changes of earth-strength static magnetic fields, pulsed magnetic fields, or alternating electric fields (60 Hz) depress the nocturnally enhanced melatonin synthesis of the pineal gland of certain mammals. No data on the effects of high-frequency electromagnetic fields on melatonin synthesis is available. In the present study, exposure to 900 MHz electromagnetic fields [0.1 to 0.6 mW/cm², approximately 0.06 to 0.36 W/kg specific absorption rate (SAR) in rats and 0.04 W/kg in Djungarian hamsters; both continuous and/or pulsed at 217 Hz, for 15 min to 6 h] at day or night had no notable short-term effect on pineal melatonin synthesis in male and female Sprague-Dawley rats and Djungarian hamsters. Pineal synaptic ribbon profile numbers (studied in rats only) were likewise not affected. The 900 MHz electromagnetic fields, unpulsed or pulsed at 217 Hz, as applied in the present study, have no short-term effect on the mammalian pineal gland. Bioelectromagnetics 18:376–387, 1997. © 1997 Wiley-Liss, Inc.