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PubMedDate not supplied

Biophysical estimation of the environmental importance of electromagnetic fields.

The rapid development of science and technology exposes living organisms to a wide range of electromagnetic fields. Some life-style and occupational conditions are associated with a level of electromagnetic fields higher than average. A series of epidemiological studies has raised concern about possible cancer risk of electromagnetic fields generated by power lines and electrical appliances. In contrast, hundreds of thousands of patients world-wide have been cured by use of electromagnetic fields. Biological effects of low-level electromagnetic radiation have become the focus of a number of studies. However, there are not enough basic scientific data related to mechanisms of action of electromagnetic fields. This paper proposes a biophysical approach to the estimation of the environmental importance of electromagnetic fields. The methods of collecting data, dosimetry, possible mechanisms of action and open problems are discussed in this review.

Electric Power Supplies↗
PubMed1999

Effects of static electromagnetic fields on chick embryo pineal gland development.

The effects of static electromagnetic fields on the development of the chick embryo pineal gland were studied. A total of 144 fertilized White Leghorn eggs were sacrificed after 5, 10 and 15 days of incubation. The stage of development was determined in all embryos using the Hamburger and Hamilton method [J Morphol 49: 88-92, 1951]. The various morphometric parameters (diameter and distance of the pineal gland and its lumen) were measured on serial 7-micron-thick sections. The data were obtained in a morphometer and processed statistically. The intensities of the static electromagnetic fields were 18 and 36 mT. Control and exposed embryos were equally distributed and randomly assigned. After 5 days of incubation, 25% of embryos exposed to a static electromagnetic field of 18 mT had a more advanced stage of development than controls and embryos exposed to 36 mT. On the 10th and 15th day, embryos exposed to either 18 or 36 mT tended to be more developed than controls. In the morphometric study, results were similar for the controls and exposed embryos after 5 and 10 days of incubation. However, the values of the 15-day-old embryos exposed to static magnetic fields were lower than the values of the controls (p > 0.01). These differences were more pronounced in the embryos exposed to 36 mT. These results seem to indicate that static electromagnetic fields affect the development and growth of embryos unequally, and that their action can depend not only on the intensity of the static electromagnetic field, but also on the length of exposure and the organ which is developing. It may be interesting to use these data in ultrastructural and physiological studies.

Animals↗
PubMed2003

[Ecological significance of electromagnetic fields: the 20th century--century of electricity, the 21st--century of magnetism].

INTRODUCTION: The biosphere consists of all ecosystems of earth and is characterized by electromagnetic fields of different frequencies. Physics and natural sciences and disciplines are focused on their origin and characteristics. NATURAL ELECTROMAGNETIC FIELDS: There is a well defined idea that natural electromagnetic activity of the Earth's atmosphere throughout evolution led to appearance of electromagnetic homeostasis, i.e. maintenance of inner electromagnetic mileu. It can be supposed that during the evolution of living organisms natural electromagnetic fields were associated with biochemical processes and as a result of natural selection became an important information system and obligatory component of life. RESULTS: The results presented here show that there is no reason to doubt that natural electromagnetic fields are an important ecologic factor. On the contrary, we have to emphasize that natural electromagnetic environment is necessary for life on the Earth. Today intensity of artificial electromagnetic fields is ten to hundred times higher than of natural electromagnetic fields. CONCLUSION: Danger from electromagnetic fields is an acute and actual problem which increases knowing that there won't be a spot without artificial electromagnetic field on our planet.

Animals↗
PubMed1996

[Combined biological effect of electromagnetic fields and chemical substances (toxic)].

The authors present results of own measurements and examinations as well as the literature data on the occurrence and effect of direct, low and high frequency electromagnetic fields and chemicals. In real working conditions and in experimental conditions, the following relations can be observed: 1) concomitant occurrence of electromagnetic fields and chemicals, e.g. processes of electrolysis, inductive and dielectric heating; 2) experimental studies of combined effect of electromagnetic fields and chemicals on e.g. cancer development: 3) drug effect modified by electromagnetic fields; 4) effect of chemicals produced in materials under the influence of electromagnetic fields. There are only a few publications on medical examinations of workers exposed simultaneously to electromagnetic fields and chemicals. However, even in those reported studies, an attempt to distinguish changes in the health state due to electromagnetic fields, and due to chemicals has field. The studies of the effect of electromagnetic fields which modify the effect of carcinogenic substances have not yielded unequivocal results. Electromagnetic fields may modify significantly the effect of some psychotropic and hormonal drugs. Under the influence of pyrolisis, induced by thermal effect of electromagnetic fields, toxic substances or substances with harmful biological effect may occur in some materials.

Animals↗
PubMed2005

Evaluation of genotoxic effects in human fibroblasts after intermittent exposure to 50 Hz electromagnetic fields: a confirmatory study.

The aim of this investigation was to confirm the main results reported in recent studies on the induction of genotoxic effects in human fibroblasts exposed to 50 Hz intermittent (5 min field on/10 min field off) sinusoidal electromagnetic fields. For this purpose, the induction of DNA single-strand breaks was evaluated by applying the alkaline single-cell gel electrophoresis (SCGE)/comet assay. To extend the study and validate the results, in the same experimental conditions, the potential genotoxicity was also tested by exposing the cells to a 50 Hz powerline signal (50 Hz frequency plus its harmonics). The cytokinesis-block micronucleus assay was applied after 24 h intermittent exposure to both sinusoidal and powerline signals to obtain information on cell cycle kinetics. The experiments were carried out on human diploid fibroblasts (ES-1). For each experimental run, exposed and sham-exposed samples were set up; positive controls were also provided by treating cells with hydrogen peroxide or mitomycin C for the comet or micronucleus assay, respectively. No statistically significant difference was detected in exposed compared to sham-exposed samples in any of the experimental conditions tested (P > 0.05). In contrast, the positive controls showed a statistically significant increase in DNA damage in all cases, as expected. Accordingly, our findings do not confirm the results reported previously for either comet induction or an increase in micronucleus frequency.

Cell Proliferation↗
PubMed1997

The effect of pulsed electromagnetic fields on instrumented posterolateral spinal fusion and device-related stress shielding.

STUDY DESIGN: This study was designed to examine stress-shielding effects on the spine caused by rigid implants and to investigate the effects of pulsed electromagnetic fields on the instrumented spine. OBJECTIVES: To investigate the effects of pulsed electromagnetic fields on posterolateral spinal fusion, and to determine if osteopenia induced by rigid instrumentation can be diminished by pulsed electromagnetic fields. SUMMARY OF BACKGROUND DATA: Although device-related osteopenia on vertebral bodies is of a great clinical importance, no method for preventing bone mineral loss in vertebrae by stiff spinal implants has been effective. METHODS: Twenty-eight adult beagles underwent L5-L6 destabilization followed by posterolateral spinal fusion. The study was divided into four groups: 1) Group CNTL: without instrumentation, without pulsed electromagnetic fields, 2) Group PEMF: without Steffee, with pulsed electromagnetic fields, 3) Group INST: with Steffee, without pulsed electromagnetic fields, 4) Group PEMF + INST: with Steffee, with pulsed electromagnetic fields. At the end of 24 weeks, the dogs were killed, and L4-L7 segments were tested biomechanically without instrumentation. Radiographs and quantitative computed tomography assessed the condition of the fusion mass. RESULTS: Stress shielding was induced in the anterior vertebral bodies of L6 with the Steffee plates; bone mineral density was increased with the addition of pulsed electromagnetic fields, regardless of the presence or absence of fixation. A decrease in flexion and bending stiffness was observed in the Group INST; pulsed electromagnetic fields did increase the flexion stiffness regardless of the presence or absence of fixation, although this was not statistically significant. CONCLUSIONS: Use of pulsed electromagnetic fields has the potential to minimize device-related vertebral-bone mineral loss.

Animals↗
PubMedDate not supplied

[Occupational exposure to electromagnetic fields in physiotherapy departments].

An assessment of the electromagnetic fields emitted from short and ultrashort wave diathermy sources and from magneto therapy operating at a frequency of 50 Hz was made to evaluate the occupational exposure to the operators. Operators were exposed to electromagnetic fields which rarely exceed the recommended limits of International Commission on Non-Ionizing Radiation Protection (ICNIRP) and American Conference of Governmental Industrial Hygienists (ACGIH). Only a measurement of electromagnetic fields near short wave diathermy equipment operating at a frequency of 27.12 MHz exposed operators to levels above those recommended by ICNIRP at a distance of 1 metre. Magnetic fields of magneto therapy exceeded residential exposition of 1 microtesla, at a distance of 4 metres.

Diathermy↗
PubMed2003

Occupational exposure to electromagnetic fields and acute leukaemia: analysis of a case-control study.

AIMS: To investigate whether the risk of acute leukaemia among adults is associated with occupational exposure to electromagnetic fields. METHODS: Probable occupational exposure to electromagnetic fields at higher than typical residential levels was investigated among 764 patients diagnosed with acute leukaemia during 1991-96 and 1510 sex and age matched controls. A job exposure matrix was applied to the self reported employment histories to determine whether or not a subject was exposed to electromagnetic fields. Risks were assessed using conditional logistic regression for a matched analysis. RESULTS: Study subjects considered probably ever exposed to electromagnetic fields at work were not at increased risk of acute leukaemia compared to those considered never exposed. Generally, no associations were observed on stratification by sex, leukaemia subtype, number of years since exposure stopped, or occupation; there was no evidence of a dose-response effect using increasing number of years exposed. However, relative to women considered never exposed, a significant excess of acute lymphoblastic leukaemia was observed among women probably exposed to electromagnetic fields at work that remained increased irrespective of time prior to diagnosis or job ever held. CONCLUSION: This large population based case-control study found little evidence to support an association between occupational exposure to electromagnetic fields and acute leukaemia. While an excess of acute lymphoblastic leukaemia among women was observed, it is unlikely that occupational exposure to electromagnetic fields was responsible, given that increased risks remained during periods when exposure above background levels was improbable.

Adolescent↗
PubMed2002

Inhibition of gap junction intercellular communication by extremely low-frequency electromagnetic fields in osteoblast-like models is dependent on cell differentiation.

Electromagnetic fields have been used to augment the healing of fractures because of its ability to increase new bone formation. The mechanism of how electromagnetic fields can promote new bone formation is unknown, although the interaction of electromagnetic fields with components of the plasma membrane of cells has been hypothesized to occur in bone cells. Gap junctions occur among bone forming cells, the osteoblasts, and have been hypothesized to play a role in new bone formation. Thus it was investigated whether extremely low-frequency (ELF) magnetic fields alter gap junction intercellular communication in the pre-osteoblastic model, MC3T3-E1, and the well-differentiated osteoblastic model, ROS 17/2.8. ELF magnetic field exposure systems were designed to be used for an inverted microscope stage and for a tissue culture incubator. Using these systems, it was found that magnetic fields over a frequency range from 30 to 120 Hz and field intensities up to 12.5 G dose dependently decreased gap junction intercellular communication in MC3T3-E1 cells during their proliferative phase of development. The total amount of connexin 43 protein and the distribution of connexin 43 gap junction protein between cytoplasmic and plasma membrane pools were unaltered by treatment with ELF magnetic fields. Cytosolic calcium ([Ca(2+)](i)) which can inhibit gap junction communication, was not altered by magnetic field exposure. Identical exposure conditions did not affect gap junction communication in the ROS 17/2.8 cell line and when MC3T3-E1 cells were more differentiated. Thus ELF magnetic fields may affect only less differentiated or pre-osteoblasts and not fully differentiated osteoblasts. Consequently, electromagnetic fields may aid in the repair of bone by effects exerted only on osteoprogenitor or pre-osteoblasts.

Animals↗
PubMed2005

Chromosomal damage in human diploid fibroblasts by intermittent exposure to extremely low-frequency electromagnetic fields.

Environmental exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) has been implicated in the development of cancer in humans. An important basis for assessing a potential cancer risk due to ELF-EMF exposure is knowledge of biological effects on human cells at the chromosomal level. Therefore, we investigated in the present study the effect of intermittent ELF electromagnetic fields (50 Hz, sinusoidal, 5'field-on/10'field-off, 2-24 h, 1 mT) on the induction of micronuclei (MN) and chromosomal aberrations in cultured human fibroblasts. ELF-EMF radiation resulted in a time-dependent increase of micronuclei, which became significant after 10 h of intermittent exposure at a flux density of 1 mT. After approximately 15 h a constant level of micronuclei of about three times the basal level was reached. In addition, chromosomal aberrations were increased up to 10-fold above basal levels. Our data strongly indicate a clastogenic potential of intermittent low-frequency electromagnetic fields, which may lead to considerable chromosomal damage in dividing cells.

Cells, Cultured↗
PubMed1983

Review of pulsing electromagnetic field therapy and its possible application to horses.

The relevant literature on electrostimulation in general, and pulsing electromagnetic fields in particular, is reviewed. DC current influences cell behaviour by affecting transmembrane ion transport, which is often under enzymatic control. Pulsing electromagnetic fields influence cell functions through adsorption of ions or dipole formation at the cell membrane. Invasive and non-invasive DC current stimulation is compared to pulsing electromagnetic fields. The mode of application of pulsing electromagnetic fields to the equine limb and suggested treatment times are briefly discussed. Two case reports are used to illustrate the effect of pulsing electromagnetic fields in equine fracture treatment.

Animals↗
PubMed2001

Photodynamic effect on cancer cells influenced by electromagnetic fields.

The synergism of low-frequency electromagnetic field treatment and photodynamic effect on killing of human cancer cells is presented. The weak pulsating electromagnetic field (PEMF) generated by Helmholtz coils in the mT range influences the permeability of cell membranes for photosensitizers. Several types of sensitizers were excited by visible light during incorporation without and with two kinds of PEMF treatment. In the first part suitable photosensitizers were selected in the absorption range between 400 and 700 nm against human myeloid leukaemia K562 and human histiocytic lymphoma U937 cells by treatment of PEMF consisting of rectangular pulse groups. In the second part amplitude and frequency dependencies were measured using sinuous PEMF and white light with the result that after 12 min the PEMF treatment enhanced photodynamic effectivity by more than 40% over the control value. Taking into account the influence of many parameters, an additional optimization will be possible by photodynamic PEMF synergism for an increased drug delivery in general.

Cell Membrane Permeability↗
PubMed1989

Fetal loss associated with two seasonal sources of electromagnetic field exposure.

We have studied two sources of electromagnetic fields where exposure is highly seasonal (ceiling cable electric heat and electrically heated beds). Because many potential confounders could not be addressed, we can make no valid statement about overall differences in abortion rates between those exposed and those not exposed to these seasonal sources. However, by analyzing seasonal trends, we have minimized the problem of unaddressed confounders because we did not look at a difference between the user and nonuser groups, but rather at a difference within the user group during months of higher exposure compared with months of lower exposure. Thus, each user group provides its own control. The function of the nonuser control group is simply to assure that any seasonal trend found in the user group is not just a general seasonal variation in reported fetal loss that can be found equally well in the nonuser population. Using this technique, we found that each user group reported fetal loss disproportionately often during the season when electromagnetic field exposure was increasing.

Abortion, Spontaneous↗
PubMed1987

Effect of pulsed electromagnetic fields on orthodontic tooth movement.

The purpose of this study was to determine whether the application of a simple surgically noninvasive, pulsed electromagnetic field could increase both the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the electromagnetic field's effects on bony physiology and metabolism and to search for possible systemic side effects. Laterally directed orthodontic force was applied to the maxillary central incisors of a sample of 40 young male, Hartley guinea pigs (20 experimental, 20 control) by means of a standardized intraoral coil spring inserted under constricting pressure into holes drilled in the guinea pigs' two maxillary central incisors. During the experimental period, the guinea pigs were placed in specially constructed, plastic animal holders with their heads positioned in an area of uniform electromagnetic field. Control animals were placed in similar plastic holders that did not carry the electrical apparatus. The application of a pulsed electromagnetic field to the experimental animals significantly increased both the rate and final amount of orthodontic tooth movement observed over the 10-day experimental period. The experimental animals also demonstrated histologic evidence of significantly greater amounts of bone and matrix deposited in the area of tension between the orthodontically moved maxillary incisors. This increase in cellular activity was also reflected by the presence of significantly greater numbers of osteoclasts in the alveolar bone surrounding the maxillary incisors of the experimental animals. After a 10-day exposure to pulsed electromagnetic field, minor changes in serologic parameters relating to protein metabolism and muscle activity were noted. The results of this study suggest that it is possible to increase the rate of orthodontic tooth movement and bone deposition through the application of a noninvasive, pulsed electromagnetic field.

Alveolar Process↗
PubMed2000

Pulsed electromagnetic field stimulation of MG63 osteoblast-like cells affects differentiation and local factor production.

Pulsed electromagnetic field stimulation has been used to promote the healing of chronic nonunions and fractures with delayed healing, but relatively little is known about its effects on osteogenic cells or the mechanisms involved. The purpose of this study was to examine the response of osteoblast-like cells to a pulsed electromagnetic field signal used clinically and to determine if the signal modulates the production of autocrine factors associated with differentiation. Confluent cultures of MG63 human osteoblast-like cells were placed between Helmholtz coils and exposed to a pulsed electromagnetic signal consisting of a burst of 20 pulses repeating at 15 Hz for 8 hours per day for 1, 2, or 4 days. Controls were cultured under identical conditions, but no signal was applied. Treated and control cultures were alternated between two comparable incubators and, therefore, between active coils; measurement of the temperature of the incubators and the culture medium indicated that application of the signal did not generate heat above the level found in the control incubator or culture medium. The pulsed electromagnetic signal caused a reduction in cell proliferation on the basis of cell number and [3H]thymidine incorporation. Cellular alkaline phosphatase-specific activity increased in the cultures exposed to the signal, with maximum effects at day 1. In contrast, enzyme activity in the cell-layer lysates, which included alkaline phosphatase-enriched extracellular matrix vesicles, continued to increase with the time of exposure to the signal. After 1 and 2 days of exposure, collagen synthesis and osteocalcin production were greater than in the control cultures. Prostaglandin E2 in the treated cultures was significantly reduced at 1 and 2 days, whereas transforming growth factor-beta1 was increased; at 4 days of treatment, however, the levels of both local factors were similar to those in the controls. The results indicate enhanced differentiation as the net effect of pulsed electromagnetic fields on osteoblasts, as evidenced by decreased proliferation and increased alkaline phosphatase-specific activity, osteocalcin synthesis, and collagen production. Pulsed electromagnetic field stimulation appears to promote the production of matrix vesicles on the basis of higher levels of alkaline phosphatase at 4 days in the cell layers than in the isolated cells, commensurate with osteogenic differentiation in response to transforming growth factor-beta1. The results indicate that osteoblasts are sensitive to pulsed electromagnetic field stimulation, which alters cell activity through changes in local factor production.

Alkaline Phosphatase↗
PubMed2004

A multicenter clinical trial on the use of pulsed electromagnetic fields in the treatment of temporomandibular disorders.

STATEMENT OF THE PROBLEM: Pulsed electromagnetic fields have shown therapeutic benefit in the treatment of numerous forms of osteoarthritis but have not been evaluated for their effects on the temporomandibular joint (TMJ). PURPOSE: The aim of this study was to examine the effects of pulsed electromagnetic fields in the treatment of patients with temporomandibular disorders (TMD). MATERIALS AND METHODS: A multicenter clinical trial compared active treatment of 36 patients using pulsed electromagnetic fields to placebo treatment of 42 patients with TMD with pain in 1 or both TMJs and/or limited opening of less than 40 mm. Subjective parameters including pain intensity, pain frequency, degree of limitation, restriction of daily life, and intensity and frequency of joint noises were evaluated using a visual analog scale. Trained, blinded examiners assessed the clinical parameters according to Research Diagnostic Criteria for temporomandibular disorders before treatment (baseline), directly after nine 1-hour treatments on consecutive working days, 6 weeks after treatment, and 4 months after treatment. Statistical evaluation was done using the Friedman test, and by paired comparison between baseline and follow-up examinations using the U test (P < .05). RESULTS: Seventy-six patients completed the study. For both the active and placebo treatment, significant improvements were seen in the subjective data (P < .01). Patients with anterior disk displacement without reduction also showed significant improvements in active mouth opening (P = .015), patients with ostheoarthritis only showed improvements in some of the subjective parameters (P < .03), and patients with anterior disk displacement with reduction showed no improvement at all. CONCLUSIONS: Pulsed electromagnetic fields had no specific treatment effects in patients with temporomandibular disorders.

Adolescent↗