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PubMed1991

[Electromagnetic fields: their biological effects and regulation].

Concern over the effects of humans of ELF-(extremely low frequency; less than 300 Hz) electromagnetic fields has rapidly increased in recent years. The effects seem to be related to gene level aberrations such as carcinogenesis and developmental malformations, but it is difficult to obtain experimental evidences on field effects. Several safety guidelines or permissible doses have been proposed for electromagnetic wave, but they mainly cover the range of microwave frequencies. Three of the guidelines made in 1989-1990 included ELF-electromagnetic fields and two newly approved guidelines on power-frequency electromagnetic fields appeared in 1990. However, they adopted considerably different values based on different theoretical standpoints. Generally, the concept of electromagnetic fields appears to be confused with that of magnetic field and thus the ideas for protective measures conflict between the two. The author first presented the concepts of electromagnetic and magnetic fields, then briefly discussed their biological effects together with the underlying mechanism, and lastly described these drafts on safety standards or permissible doses. Since subtle and difficult problems remain to be resolved, further investigation will be required in order to put these guidelines into practice.

Electromagnetic Fields↗
PubMed2000

Exposure to electromagnetic fields and risk of central nervous system disease in utility workers.

Occupational exposure to electromagnetic fields has been associated with neurological diseases such as amyotrophic lateral sclerosis, senile dementia, Parkinson disease, and Alzheimer disease. I studied the incidence of central nervous system diseases in 30,631 persons employed in Danish utility companies between 1900 and 1993. I linked the cohort to the nationwide, population-based Danish National Register of Patients and compared the numbers of cases of these diseases observed between 1978 and 1993 with the corresponding rates in the general population. In addition I fit to the data on utility workers a multiplicative Poisson regression model in relation to estimated levels of exposure to 50-Hz electromagnetic fields. Overall, there was an increase in risk for senile dementia and motor neuron diseases combined. The incidences of Parkinson disease, Alzheimer disease, and other diseases of the central nervous system were essentially unrelated to exposure to electromagnetic fields. A decreased risk of epilepsy compared with the general population probably reflects a healthy worker effect; I observed an increased risk of epilepsy based on internal comparisons. The increased risk for senile dementia and motorneuron diseases may be associated with above-average levels of exposure to electromagnetic fields.

Adult↗
PubMed2003

Pulsed electromagnetic fields prevent osteoporosis in an ovariectomized female rat model: a prostaglandin E2-associated process.

With the use of Helmholtz coils and pulsed electromagnetic field (PEMF) stimulators to generate uniform time varying electromagnetic fields, the effects of extremely low frequency electromagnetic fields on osteoporosis and serum prostaglandin E(2) (PGE(2)) concentration were investigated in bilaterally ovariectomized rats. Thirty-five 3 month old female Sprague-Dawley rats were randomly divided into five different groups: intact (INT), ovariectomy (OVX), aspirin treated (ASP), PEMF stimulation (PEMF + OVX), and PEMF stimulation with aspirin (PEMF + ASP) groups. All rats were subjected to bilateral ovariectomy except those in INT group. Histomorphometric analyses showed that PEMF stimulation augmented and restored proximal tibial metaphyseal trabecular bone mass (increased hard tissue percentage, bone volume percentage, and trabecular number) and architecture (increased trabecular perimeter, trabecular thickness, and decreased trabecular separation) in both PEMF + OVX and PEMF + ASP. Trabecular bone mass of PEMF + OVX rats after PEMF stimulation for 30 days was restored to levels of age matched INT rats. PEMF exposure also attenuated the higher serum PGE(2) concentrations of OVX rats and restored it to levels of INT rats. These experiments demonstrated that extremely low intensity, low frequency, single pulse electromagnetic fields significantly suppressed the trabecular bone loss and restored the trabecular bone structure in bilateral ovariectomized rats. We, therefore, conclude that PEMF may be useful in the prevention of osteoporosis resulting from ovariectomy and that PGE(2) might relate to these preventive effects.

Animals↗
PubMedDate not supplied

[The effect of low-frequency electromagnetic fields on the neuroendocrine system].

This paper presents literature data about effects of low-intensity variable electromagnetic fields on the neuroendocrine system of experimental animals. We mostly paid attention to electromagnetic fields frequently found in our environment, in technological processes, even in our everyday life. This study shows that the regulatory systems (nervous and endocrine) are extremely sensitive to effects of electromagnetic fields. In regard to structures of the central nervous system hypothalamus shows particularly high sensitivity whereas we can consider a hypothesis that effects of this physical factor may be expected in other systems too. It has been emphasized that the effects of electromagnetic fields on regulatory mechanisms may be connected with primary disturbances on the cellular and subcellular (mitochondrial) level.

Animals↗
PubMed2006

[Effects of electromagnetic fields of different frequencies on proliferation and DNA damage of gallbladder cancer cells].

OBJECTIVE: To study the effects of low-power electromagnetic fields of different frequencies on proliferation and DNA damage of gallbladder cancer cells. METHODS: The cell growth curve was drawn and single cell gel electrophoresis performed to evaluate the proliferation and DNA damage of gallbladder cancer cells respectively after the cells were exposed to electromagnetic fields of different frequencies. RESULTS: After exposure to low-power electromagnetic fields of different frequencies (0.1-40 MHz), the cells displayed significant changes with obvious cell proliferation inhibition and DNA strand breakage. CONCLUSION: Low-power electromagnetic fields within the range of 0.1-40 MHz may impair the DNA strand and cause inhibition of proliferation of the gallbladder cancer cells, and these effects are related to the frequency of the electromagnetic fields but not in a linear fashion.

Cell Line, Tumor↗
PubMed2006

Biophysical stimulation with pulsed electromagnetic fields in osteonecrosis of the femoral head.

BACKGROUND: Osteonecrosis of the femoral head is the end point of a disease process that results in bone necrosis, joint edema, and cartilage damage. It leads to joint arthritis that necessitates total hip arthroplasty in many patients. Because of its positive effects on osteogenesis and its chondroprotective effect of articular cartilage, pulsed electromagnetic field stimulation has been proposed as a method to prevent or delay the progression of osteonecrosis. METHODS: A retrospective analysis of the results of treatment with pulsed electromagnetic field stimulation of seventy-six hips in sixty-six patients with osteonecrosis of the femoral head was performed. Patients with Ficat stage I, II, or III osteonecrosis of the femoral head were treated with pulsed electromagnetic field stimulation for eight hours per day for an average of five months. Clinical and diagnostic imaging information was collected at the start of the treatment and at the time of follow-up. The primary end point analyzed was the avoidance of hip surgery, and the secondary end point was limiting the radiographic progression (according to Ficat stage) of osteonecrosis of the femoral head. RESULTS: Fifteen hips required a total hip arthroplasty; twelve of these hips were in patients with Ficat stage-III disease. The need for total hip arthroplasty was significantly higher in patients with Ficat stage-III disease than in patients with Ficat stage-I (p < 0.0001) or II (p < 0.01) disease at the beginning of treatment. Pulsed electromagnetic fields preserved 94% of Ficat stage-I or II hips. Furthermore, radiographic progression (according to Ficat stage) occurred in twenty hips (26%). Pain, present in all patients at the start of the treatment, disappeared after sixty days of stimulation in thirty-five patients (53%) and was of moderate intensity in seventeen patients (26%). CONCLUSIONS: The results of this study confirm that pulsed electromagnetic field treatment may be indicated in the early stages of osteonecrosis of the femoral head (Ficat stages I and II). Pulsed electromagnetic field stimulation may be able to either preserve the hip or delay the time until surgery. The authors hypothesize that the short-term effect of pulsed electromagnetic field stimulation may be to protect the articular cartilage from the catabolic effect of inflammation and subchondral bone-marrow edema. The long-term effect of pulsed electromagnetic field stimulation may be to promote osteogenic activity at the necrotic area and prevent trabecular fracture and subchondral bone collapse. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Adult↗
PubMed2006

Propagation theories of partially coherent electromagnetic fields based on coherent or separated-coordinate mode decomposition.

Propagation theories of partially coherent electromagnetic fields based on coherent mode decomposition or separated-coordinate mode decomposition are proposed. With the proposed propagation theories, various powerful theories for the propagation of fully coherent electromagnetic fields can be used for the propagation of partially coherent electromagnetic fields. The proposed theories are applicable to any propagation problem of partially coherent electromagnetic fields governed by linear Maxwell equations. Some examples are provided to illustrate the validity of the proposed theories.

Journal Article↗
PubMed1988

Endothelial cell response to pulsed electromagnetic fields: stimulation of growth rate and angiogenesis in vitro.

The effects of pulsed electromagnetic fields on the repopulation rate of denuded regions of endothelial cell monolayers and on endothelial cell reorganization into complex vessellike structures was monitored in vitro by using human umbilical vein and bovine aortic endothelial cells. A small (20-40%) but statistically significant enhancement in growth rate of partially denuded endothelial cell monolayers as determined by tritiated thymidine incorporation was observed in the presence of pulsed electromagnetic fields. Morphologically, endothelial cells entering the denuded regions were observed to be elongated, often connecting end to end to form a mycelial or "sprouting" pattern when exposed to pulsed electromagnetic fields. This was in contrast to cells outside of the field which had a more cuboidal morphology. Complete disruption of the endothelial cell monolayer by passaging the cells with EDTA-trypsin resulted in reorganization of some of the cells into three-dimensional vessellike structures after as little as 5-8 hours in the presence of the pulsed electromagnetic field. This reorganization occurred in the presence of heparin, endothelial cell growth factor, and a competent fibronectin matrix. Vascularization for comparable cultures outside of the field did not occur during the time-course of the experiments. Discrete stages of neovascularization were observed in the presence of the field that were qualitatively similar to stages of angiogenesis observed in vivo.

Animals↗
PubMed1998

Effects of pulsed high-frequency electromagnetic fields on the neuroendocrine system.

The influence of pulsed high-frequency electromagnetic fields emitted from a circularly polarized antenna on the neuroendocrine system in healthy humans was investigated (900 MHz electromagnetic field, pulsed with 217 Hz, average power density 0.02 mW/cm2). Nocturnal hormone profiles of growth hormone (GH), cortisol, luteinizing hormone (LH) and melatonin were determined under polysomnographic control. An alteration in the hypothalamo-pituitary-adrenal axis activity was found with a slight, transient elevation in the cortisol serum level immediately after onset of field exposure which persisted for 1 h. For GH, LH and melatonin, no significant effects were found under exposure to the field compared to the placebo condition, regarding both total hormone production during the entire night and dynamic characteristics of the secretion pattern. Also the evaluation of the sleep EEG data revealed no significant alterations under field exposure, although there was a trend to an REM suppressive effect. The results indicate that weak high-frequency electromagnetic fields have no effects on nocturnal hormone secretion except for a slight elevation in cortisol production which is transient, pointing to an adaptation of the organism to the stimulus.

Adolescent↗
PubMed1997

Evaluation of potential genotoxicity of pulsed electric and electromagnetic fields used for bone growth stimulation.

Medical devices emitting pulsed electric and electromagnetic fields have been found to be effective for a number of clinical applications including stimulation of bone and tissue growth. To determine whether pulsed fields of the type used in these clinical applications present a mutagenic hazard, electric and electromagnetic fields at two exposure levels were tested in the Ames test, CHO cell chromosomal aberration assay, BALB/3T3 cell transformation assay and unscheduled DNA synthesis assay in primary rat hepatocytes. For both field types, initial and independent repeat studies were performed for each assay at both clinical and supra clinical doses. In all assays, the results show a lack of cytotoxic, transforming and mutagenic activity. The data suggest that pulsed electric and electromagnetic fields of the type and dose levels used in bone growth stimulation lack mutagenic and transforming activity.

3T3 Cells↗
PubMed2000

[Electromagnetic diagnostic and therapeutic equipment--patient and medical personnel exposure to electromagnetic fields].

The mechanisms responsible for the interaction between electromagnetic fields and the biological matter were reviewed. For each of the mechanisms one or more relevant diagnostic and/or therapeutic methods were applied. The characteristics of exposure to electromagnetic fields generated by individual types of medical equipment among the diagnosed or treated subjects, as well as the magnitude of exposure observed in the medical personnel are present.

Diagnostic Imaging↗
PubMed1995

The influence of electromagnetic fields on human brain activity.

Possible effects of electromagnetic fields on human brain activity were studied. In a single-blind, cross-over-designed and placebo-controlled study 36 volunteers were exposed firstly to an electromagnetic field originating form a MediLine "MEGA-WAVE 150/1" therapy instrument and secondly to a field originating from a mobile, digital tetlephone as used for wireless telecommunication. All volunteers also underwent a control experiment with no field exposure. Application of the MEGA-WAVE instrument caused an increase in EEG power in the frequency bands Alpha2, Beta1 and Beta2 during and after field exposure. Operation of the mobile telephone caused an increase in the same frequency bands with a delay of approximately 15 minutes after exposure.

Brain↗
PubMed1986

The effect of pulsed electromagnetic fields on the corrosion of a chromium-cobalt-nickel alloy orthopaedic implant.

In order to assess whether pulsed electromagnetic fields influence the rate of corrosion of orthopaedic metal implants, an alloy, called MP-35N, was exposed for 3 wk to a pulsed electromagnetic field. The results demonstrated that while there was a progressive release of the major constituents of MP-35N, i.e. cobalt (32.5%), nickel (36%), and chromium (20%), with time, corrosion was not significantly higher in the presence of the pulsed electromagnetic field when compared to that of the non-exposed pins. There was a significantly higher release of cobalt by the control pins after 5, 10, and 15 d incubation when compared with the pulsed pins. These findings were confirmed by SEM which demonstrated progressive surface corrosion with time and that the extent of corrosion was similar for both the control and pulsed pins. These results suggest that pulsed electromagnetic fields have no effect in promoting the surface corrosion of orthopaedic metallic implants.

Alloys↗
PubMed2003

The effect of the duration of exposure to the electromagnetic field emitted by mobile phones on human attention.

Previous findings suggested the facilitating effect of the electromagnetic field emitted by mobile phones on human attention. This study aimed to examine the relationship between the facilitating effect and the duration of exposure to the electromagnetic field emitted by mobile phones on human attention. Seventy-eight university students were randomly assigned to either an experimental or a control group. Their performance in the administered attention tasks was compared. Participants in the experimental group performed better on one of the two measures of attention only after they had been exposed to the electromagnetic field emitted by the mobile phone for some time. The results seem to suggest that attention functions may be differentially enhanced after exposing to the electromagnetic field emitted by mobile phones. Furthermore, this transient facilitation effect might be dose dependent.

Adolescent↗
PubMed1991

Exposure to electromagnetic fields and risk of leukemia.

Using the data from a case-control study performed in 958 age, sex and place of residence matched pairs of adult inhabitants of Polish towns, the risk of leukemia related to work in electromagnetic fields. Information concerning exposure to electromagnetic fields for 958 cases and corresponding number of nonionizing electromagnetic fields were mainly: short-wave diathermy, heat sealer, capacitor discharge welder and induction welder. For workers exposed to electromagnetic fields, the odds ratio (OR) was not significantly elevated all leukemias (p greater than 0.05).

Adult↗
PubMed2005

Erythrocyte rouleau formation under polarized electromagnetic fields.

We study the influence of an external electromagnetic field of 1.8 GHz in the formation or disaggregation of long rouleau of identical erythrocyte cells. In particular we calculate the variation of the transmembrane potential of an individual erythrocyte illuminated by the external field due to the presence of the neighboring erythrocytes in the rouleau, and compare the total electric energy of isolated cells with the total electric energy of the rouleau. We show that the polarization of the external electromagnetic field plays a fundamental role in the total energy variation of the cell system, and consequently in the formation or disaggregation of rouleau.

Animals↗
PubMed2002

Function of Ca-pump in sarcoplasmic reticulum of rat myocardium during adaptation to electromagnetic field.

We studied the effect of adaptation to electromagnetic field on functional state of Ca-pump in sarcoplasmic reticulum, intensity of lipid peroxidation, and energy metabolism in rat myocardium. Membrane viscosity was assessed in crude preparation of myocardial sarcoplasmic reticulum. Adaptation to electromagnetic field did not change the rate of endogenous respiration, including ouabain-sensitive respiration, but potentiated coupling between catalytic activity and Ca-transporting capacity of Ca-pump. It is hypothesized that modification of structural and functional properties of the membrane due to inhibition of free radical processes increases functional activity of Ca-pump in sarcoplasmic reticulum.

Adaptation, Physiological↗
PubMed2000

Neural and behavioral teratological evaluation of rats exposed to ultra-wideband electromagnetic fields.

Several investigators have reported teratologic effects of electromagnetic field exposure. The majority of these studies have been performed at levels of exposure that could produce substantial heating of the animals. New and unique sources of ultra-wideband (UWB) electromagnetic fields are currently being developed and tested that are capable of generating nonthermalizing, high-peak-power, microwave (MW) pulses with nanosecond (ns) pulse widths, picosecond (ps) rise times, and an UWB of frequencies. Our study was performed to determine if teratological changes occur in rat pups as a result of (i) daily UWB exposures during gestation days 3-18, or (ii) as a result of both prenatal and postnatal (10 days) exposures. Dams were exposed either to (i) UWB irradiation from a Kentech system that emitted a 55 kV/m-peak E field, 300 ps rise time, and a 1.8 ns pulse width, average whole-body specific absorption rate 45 mW/kg; (ii) sham irradiation; or (iii) a positive control, lead (Pb) acetate solution (2000 microg/ml) continuously available in the drinking water. Offspring were examined for ontogeny (litter size, sex-ratios, weights, coat appearance, tooth-eruption, eye-opening, air-righting, and ultrasonic stress vocalizations). Male pups were tested on various performance measures (locomotor, water-maze learning, and fertilization capabilities). The pups postnatally exposed were examined for hippocampal morphology and operant behavior. Behavioral, functional, and morphological effects of UWB exposure were unremarkable with these exceptions: (i) The UWB-exposed pups emitted significantly more stress vocalizations than the sham-exposed pups; (ii) the medial-to-lateral length of the hippocampus was significantly longer in the UWB-exposed pups than in the sham-exposed animals; (iii) male offspring exposed in utero to UWB mated significantly less frequently than sham-exposed males, but when they did mate there was no difference in fertilization and offspring numbers from the sham group. There does not appear to be a unifying physiological or behavioral relationship among the significant differences observed, and our findings could be due to the expected spurious results derived when a large number of statistical comparisons are made. Significant effects found between our positive-controls and other groups on numerous measures indicates that the techniques used were sensitive enough to detect teratological effects. Bioelectromagnetics 21:524-537, 2000. Published 2000 Wiley-Liss, Inc.

Animals↗