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PubMed2004

Are environmental electromagnetic fields genotoxic?

Long-term exposure to extremely-low-frequency electromagnetic fields (ELF EMFs) greater than 0.4 microT has been linked, by epidemiological studies, to a small elevated risk of childhood leukaemia. Laboratory-based experiments have been claimed to show that ELF EMFs induce a variety of biological responses, although these claims are controversial. Recent experiments by Ivancsits et al. [Mutat. Res. 519 (2002) 1; Int. Arch. Occup. Environ. Health 76 (2003) 431; Mech. Age. Dev. 124 (2003) 847; H.W. Rüdiger, S. Ivancsits, E. Diem, O. Jahn, Genotoxic effects of ELF-EMF on human cells in vitro, Bioelectromagnetics Society 25th Annual Meeting, Maui, USA, 2003] suggest that ELF EMFs are genotoxic, on the basis of observations that intermittent exposures induce single-strand breaks (SSB) and double-strand DNA breaks (DSB) in the DNA of cultured human fibroblasts. The implications of these findings are discussed.

Animals↗
PubMed1999

Pulsed high-frequency electromagnetic field affects human sleep and sleep electroencephalogram.

To investigate whether the electromagnetic field (EMF) emitted by digital radiotelephone handsets affects the brain, healthy, young subjects were exposed during an entire night-time sleep episode to an intermittent radiation schedule (900 MHz; maximum specific absorption rate 1 W/kg) consisting of alternating 15-min on-15-min off intervals. Compared with a control night with sham exposure, the amount of waking after sleep onset was reduced from 18 to 12 min. Spectral power of the electroencephalogram in non-rapid eye movement sleep was increased. The maximum rise occurred in the 10-11 Hz and 13.5-14 Hz bands during the initial part of sleep and then subsided. The results demonstrate that pulsed high-frequency EMF in the range of radiotelephones may promote sleep and modify the sleep EEG.

Adult↗
PubMed2005

Electromagnetic field for a focused light sheet incident on a plane surface.

A solution procedure is developed for the determination of the electromagnetic field that results from the interaction of a focused light sheet with a plane surface. The effects of angle of incidence, relative index of refraction, polarization, and incident light sheet profile on the resulting electromagnetic field distribution are demonstrated.

Journal Article↗
PubMed2006

[Calibration of measurement devices used in electromagnetic field monitoring in the occupational and municipal environments].

The accuracy of electromagnetic field (EMF) standard measurements are relatively low as compared to the accuracy of other standards of physical magnitudes mainly because all EMF components are defined with use of indirect methods. This approach leads to error dependent on methods currently used to determine standard field, available equipment, frequency range and other factors. One way to eliminate these errors is a simultaneous use of two or more methods or intercomparison of standards performed within one's own laboratory or in comparation with other national or/and foreign laboratories. The accuracy of a meter cannot exceed the accuracy of a standard applied to calibrate it. Unfortunately, this condition is frequently violated and (probably because of commercial reasons) the declared accuracy of meters available on the market exceed that of the best EMF standards. Some sources of errors in the work of several factors limiting accuracy of the EMF standards are discussed in details. The analysis reveals the need for appropriate choice of calibration method, taking into account EMF component, required accuracy, EMF intensity, frequency, and equipment applied. Such an approach and the use of calibration factors, estimated theoretically or/and experimentally, may contribute to remarkable improvement of the accuracy of procedures being used.

Calibration↗
PubMed1992

Electromagnetic fields and cancer risks.

Cancer was first associated with exposure to electromagnetic fields (EMF) in 1979 when Wertheimer and Leeper reported that children dying from cancer resided more often in homes believed to be exposed to higher EMF than did healthy control children. The risks were as high as 2.23 (1.56-3.18) 3.09 (1.68-5.71) for all cancers, 2.98 (1.72-5.15) for leukemia and 2.40 (1.08-5.36) for brain cancers. Wire configuration around houses was used as a surrogate for direct EMF exposure measurements. Wertheimer's finding of an association between cancer and wire configuration around houses has been replicated in two recent studies. However, direct measurement of EMF fields in houses of cancer children have not yielded the same results as the wire configuration around houses, thereby jeopardizing the hypothesis of an association between EMF and cancer. To comprehend the putative association between residential exposure to EMF and childhood cancer, one would have to understand what is hidden behind the notion of 'wire configuration' around the house. In parallel with residential studies, scores of studies were conducted among workers occupationally exposed to EMF. What have we learned from these occupational studies? Hypotheses generating and case control studies have revealed the existence of an excess risk of leukemia among electrical workers. Pooled results have estimated the risk for all leukemia to be 1.18 (1.09-1.29) and for acute myeloid leukemia 1.46 (1.27-1.64). An increased risk of leukemia among electrical workers does not necessarily mean that EMF is a causal agent, other chemicals such as benzene, creosote, solvent, could possibly account for it but this has yet to be confirmed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Electromagnetic fields inhibit endothelin-1 production stimulated by thrombin in endothelial cells.

Electromagnetic field (EMF) radiation has been found to induce arteriolar dilatation, but the mechanism of action remains largely unknown. This study investigated the effect of EMF radiation on the production of endothelin-1 (ET-1), a potent vasoconstrictor, by cultured endothelial cells. EMF radiation reduced ET-1 basal levels in human umbilical vein and microvascular endothelial cells, but failed to reduce ET-1 basal levels in bovine and human aortic endothelial cells. EMF radiation significantly inhibited thrombin-stimulated ET-1 production in all four endothelial cell types in a dose-dependent manner. EMF radiation significantly inhibited thrombin-induced endothelin-1 mRNA expression in all four cell types. The inhibitory effect of EMF radiation on ET-1 production was abolished by the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (10(-3) mol/1). These results demonstrate that EMF radiation modulates ET-1 production in cultured vascular endothelial cells and the inhibitory effect of EMF radiation is, at least partly, mediated through a nitric oxide-related pathway.

Animals↗
PubMedDate not supplied

[Subjective non-specific symptoms related with electromagnetic fields: description of 2 cases].

In Italy, as in other countries, an apparently increasing number of subjects is reporting a variety of subjective symptoms that the subjects themselves refer to the exposure to electric, magnetic or electromagnetic fields (EMF) from nearby electric appliances, cellular phones, antennas, etc. Terms like electricity hypersensitivity (EHS), EMF hypersensitivity, or other similar, are frequently adopted to describe such symptoms; nevertheless, up to now, these terms are not entered the medical terminology. No accepted diagnostic criteria or procedures for the diagnosis of EHS are currently available. Furthermore, apart from the subject's self-attribution of the symptoms to EMFs, no direct cause-effect relationship between EHS symptoms and electromagnetic fields has been proved; additionally, evidence of a possible pathogenetic mechanism is lacking. In this paper, two cases developing symptoms of EHS ascribed to overhead power line in the proximity of their house are discussed. Nervous system (asthenia, depression, paraesthesias etc.), cardiovascular system (cardiac palpitations) and the skin (tingling, itching, etc.), are mostly (but not exclusively) involved. Based on available scientific knowledge, the rationale for an approach to subjects claiming for EHS is discussed. The establishment of a National archive for the collection of cases is communicated.

Electromagnetic Fields↗
PubMed1999

Electromagnetic fields influence NGF activity and levels following sciatic nerve transection.

Pulsed electromagnetic fields (PEMF) have been shown to increase the rate of nerve regeneration. Transient post-transection loss of target-derived nerve growth factor (NGF) is one mechanism proposed to signal induction of early nerve regenerative events. We tested the hypothesis that PEMF alter levels of NGF activity and protein in injured nerve and/or dorsal root ganglia (DRG) during the first stages of regeneration (6-72 hr). Rats with a transection injury to the midthigh portion of the sciatic nerve on one side were exposed to PEMF or sham control PEMF for 4 hr/day for different time periods. NGF-like activity was determined in DRG, in 5-mm nerve segments proximal and distal to the transection site and in a corresponding 5-mm segment of the contralateral nonoperated nerve. NGF-like activity of coded tissue samples was measured in a blinded fashion using the chick DRG sensory neuron bioassay. Overall, PEMF caused a significant decrease in NGF-like activity in nerve tissue (P < 0.02, repeated measures analysis of variance, ANOVA) with decreases evident in proximal, distal, and contralateral nonoperated nerve. Unexpectedly, transection was also found to cause a significant (P=0.001) 2-fold increase in DRG NGF-like activity between 6 and 24 hr postinjury in contralateral but not ipsilateral DRG. PEMF also reduced NGF-like activity in DRG, although this decrease did not reach statistical significance. Assessment of the same nerve and DRG samples using ELISA and NGF-specific antibodies confirmed an overall significant (P < 0.001) decrease in NGF levels in PEMF-treated nerve tissue, while no decrease was detected in DRG or in nerve samples harvested from PEMF-treated uninjured rats. These findings demonstrate that PEMF can affect growth factor activity and levels, and raise the possibility that PEMF might promote nerve regeneration by amplifying the early postinjury decline in NGF activity.

Animals↗
PubMed2005

Loss of interstitial cells of Cajal after pulsating electromagnetic field (PEMF) in gastrointestinal tract of the rats.

Exposure to the magnetic field has remarkably increased lately due to fast urbanization and widely available magnetic field in diagnosis and treatment. However, biological effects of the magnetic field are not well recognized. The myoelectric activity recorded from the gastrointestinal and urinary systems is generated by specialized electrically active cells called interstitial cells of Cajal (ICCs). Thus it seems rational that ICC have significant vulnerability to physical factors like an electromagnetic field. The aim of this study was to evaluate the influence of pulsating electromagnetic field (PEMF) (frequency 10 kHz, 30ms, 300 muT burst, with frequency 1Hz) on ICCs density in the rat gastrointestinal tract. Rats were divided into two groups (n=32). The first group was exposed to PEMF continuously for 1, 2, 3, and 4 weeks (n = 16), and the second group (n=16) served as a control. Tissue samples of the rat stomach, duodenum and proximal colon were fixed and paraffin embedded. The tangential sections of 5 microm thickness were stained immunohistochemically with anti-c-Kit (sc-168) antibody and visualized finally by DAB as chromogen (brown end product). C-Kit positive branched ICC-like cells were detected under the light microscope, distinguished from the c-kit-negative non-branched smooth muscle cells and from the c-kit positive but non-branched mast cells and quantitatively analyzed by MultiScan computer program. Apoptosis detection was performed with rabbit anti-Bax polyclonal antibody (Calbiochem, Germany) and LSAB 2 visualization system. The surface of c-Kit immunopositive cells decreased after exposure to PEMF in each part of the gastrointestinal tract. Reduced density of ICCs was related to exposure time. The most sensitive to PEMF were ICCs in the fundus of the stomach and in the duodenum, less sensitive were ICCs in the colon and pacemaker areas of the stomach. No marked changes in ICC density in the pyloric part of the stomach were observed. We demonstrate that the PEMF induced apoptosis dependent decrease in ICC expression.

Animals↗
PubMed1989

Role of pulsed electromagnetic fields in recalcitrant non-unions.

Twenty-nine patients of recalcitrant nonunion of long bones were treated by pulsed electromagnetic fields in an attempt to bring about osteogenesis. The pulse used was rectangular, equal mark space wave in the astable, continuous mode operating at a frequency of 40 Hertz. The success rate was 82.5%. The result was not dependent on the age, sex, time of nonunion or the presence of infection. However, the results were uniformly poor when infection and fracture instability were coexistent in the same patient.

Adult↗
PubMed1989

Cell surface changes during electromagnetic field exposure.

Fibroblasts from 5 1/2-day-old chick embryos go through a sequential series of changes when exposed to a constant electromagnetic field (EMF) of 10 V/cm. These changes include rounding up, becoming bipolar in shape, assuming a cylindrical profile, elongating perpendicular to the EMF, and migrating to the cathode. These morphological changes are associated with changes of the cell surface, which include the formation of filopodia and extensive sheet-like contacts on the cathodic cell surface, the retraction of processes and the formation of focal contacts on the anodic cell surface.

Animals↗
PubMedDate not supplied

In vitro low frequency electromagnetic field effect on fast axonal transport.

The objective of this study was to evaluate the effects of a low frequency electromagnetic field on fast axonal transport for future neuroprosthetic applications. Changes in speeds and densities of retrograde fast organelle transport in rat sciatic nerve preparations were measured in vitro upon exposure to 15 and 50 Hz pulsed magnetic fields with peak intensities of 4.4 and 8.8 mT. Maximum current density of the induced eddy current was calculated to be about 40 microA/cm2. Video enhanced differential interference contrast microscopy was used to record axons supporting active organelle transport. Strong effects were observed in myelinated axons (cessation of transport in up to 10 min). Such effects may eventually be used as part of a neuroprosthesis to noninvasively modify or couple to various parts of the nervous system.

Animals↗
PubMedDate not supplied

[The effects of different types of pulsed electromagnetic fields on fibroblast cell cultures].

UNLABELLED: The aim of this study is to determine which is the most effective pulsed electromagnetic field (PEMF) on a fibroblastic culture cells. MATERIAL AND METHODS: Five different types of PEMF are generated by a pulsed generator created by the author. The electric signal, received by a reference coil is pulse bursts type. The growth rate of a fibroblastic culture cells is measured with and without different types of PEMF. RESULTS: Comparative results showed the the most effective type of PEMF is characterized by a 15 mV positive amplitude of the signal and a 15 Hz frequency of the bursts. The intermittent stimulation (8 hours/day) was more effective than continuous stimulation.

Cells, Cultured↗
PubMed2005

Ultrastructural organization of epiphysis in rats under the action of electromagnetic fields and during mammary carcinogenesi.

Experiments conducted by the authors, as well as clinical studies, show that in addition to hormonal mis-balance, development of mammary gland cancer is significantly influenced by the action of low frequency electromagnetic fields on epiphysis. By reducing the production of melatonin it increases the risk of development of mammary gland tumors. The review of scientific literature indicates that pinealocytes are the main morphological substrate responsible for functional activity of pineal cells. When estimating large specific weight of lipids, many researchers point to the dependence of their presence in epiphysis on the level of melatonin. It is thought that hormones of pineal cells are deposited in the form of lipid drops. The most characteristic feature in the structure of pinealocytes is the presence of large number of various size complexes in their bodies and appendices. According to many authors this could be the form of depositing the secretory products of pinealocytes, such as melatonin, biological amines, etc. Ultrastructure characteristic of pinealocytes described in the review provides deeper understanding of the fine structure morpho-physiology of epiphysis, enable to point out the peculiarities of its functionality under the influence of electromagnetic fields and discover the organizational structure of pineal body at a time of the mammary gland tumor development.

Animals↗
PubMed2002

Structure of electromagnetic field excited by an electron bunch in a semi-infinite dielectric-filled waveguide.

The exact solution of a problem on electromagnetic field excitation by a thin annular charged bunch in a semi-infinite round cylindrical waveguide with metal sidewalls and solid homogeneous dielectric filling is obtained. Expressions for all components of electromagnetic field are derived. These formulas describe the excited field at any point and any moment of time. In contrast to previous works, where asymptotic methods (saddle-point technique) were used, we applied a number of successive conformal transformations of integration area in order to carry out the inverse Fourier transformation. Integration along the initial infinite straight-line contour was substituted by integration along the closed circular contour. This allowed us to separate out the integral presentation of the cylindrical Bessel function of first kind and obtain the final solution in the form of infinite converging series. The process of integration is presented in detail. Both cases, when the Cherenkov resonance condition is satisfied and when this condition is not satisfied, are considered. Spatial pictures of field excited by a finite-size electron bunch are calculated numerically and discussed. In the case of the Cherenkov resonance the drift of excited wake field after the bunch with group velocity is demonstrated, and in the nonresonance case the appearance of impulse of transition radiation and the presence of precursor of the signal are shown.

Journal Article↗
PubMed1992

Effects of pulsing electromagnetic fields on the ligament healing in rabbits.

Effects of pulsing electromagnetic fields (PEMFs) on ligament healing were investigated using 80 rabbits. All animals received square resection (4 mm x 4 mm) of both patellar ligaments in full thickness at their center. They were divided into 4 groups of 20 rabbits each and stimulated with different electromagnetic intensity of 0 (control), 2, 10, and 50 gauss (G) for 6 hr daily. Pulse frequency and pulse width were 10 Hz and 25 microseconds, respectively. After PEMFs stimulations for 1, 2, 3 and 4 weeks, 5 animals of each group were euthanized and the regenerated tissue at the defective portion was investigated histologically and biomechanically. Histologically, the tissue stimulated by PEMFs showed an earlier increase in capillaries and fibroblasts and more matured, prominent longitudinal orientation of collagen fibers than those of control groups. Among the rabbits stimulated electromagnetically, those stimulated at 50 G revealed the earliest ligament healing. Tensile strength of regenerated ligament tissues of any PEMFs groups increased significantly at 1 and 2 weeks after operation, however, at 3 and 4 weeks after operation, there were no significant differences between groups. Among these values, those of 50 G group were the highest consistently during most of the experimental period. From the above results, PEMFs enhanced the earlier stage of ligament healings and 50 G gauss seemed to be the most effective among the 3 field intensities used. This promoting effect may potentiate the earlier recovery of the function after the ligament injury.

Animals↗
PubMed1995

Time-dependent hematological changes in workers exposed to electromagnetic fields.

A World War II-era study, involving the effects of electromagnetic fields (EMFs) emanating from radars and high-frequency radios on the blood of exposed workers, was analyzed for evidence of the effect of time in the manifestation of changes in the hematological system. Statistically significant correlations between increasing white blood cell count and average daily exposure, months of exposure, and total duration of exposure to EMFs were found. Changes in cell count were within the normal range, and thus their relation to epidemiological studies linking EMFs and leukemia, if any, is unclear. Results suggest that the time of exposure may be an additional factor (along with field strength, and perhaps frequency) in ascertaining the safety of EMF exposure.

Blood↗
PubMed1997

Effects of static magnetic and pulsed electromagnetic fields on bone healing.

The purpose of the present study was to evaluate the healing pattern of an experimentally induced osteotomy in Hartley guinea pigs in the presence of static magnetic and pulsed electromagnetic fields. The sample consisted of 30 Hartley guinea pigs 2 weeks of age divided into 3 groups: pulsed electromagnetic, static magnetic, and control. An osteotomy was performed in the mandibular postgonial area in all groups under general anesthesia. During the experimental period of 9 days, the animals were kept in experiment cages 8 hours per day, the first two groups being in the presence of pulsed electromagnetic and static magnetic field, respectively. Based on histologic results, both static and pulsed electromagnetic fields seemed to accelerate the rate of bone repair when compared to the control group. The osteotomy sites in the control animals consisted of connective tissue, while new bone had filled the osteotomy areas in both magnetic field groups.

Animals↗