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PubMed2005

In vitro increase of the fluid-phase endocytosis induced by pulsed radiofrequency electromagnetic fields: importance of the electric field component.

Nowadays, due to the wide use of mobile phones, the possible biological effects of electromagnetic fields (EMF) become a public health general concern. Despite intensive research, there are no widely accepted theories about the interactions between EMFs and living cells, and the experimental data are often controversial. We examined the effects of mobile phones EMF (envelope frequency of 217 Hz, carrier frequency of 900 MHz and pulse duration of 580 micros) or its pure, low-frequency pulsed electric field component on fluid-phase endocytosis. In both cases, with exposures exceeding 10 min, an increase of the fluid-phase endocytosis rate was observed ( approximately 1.5-fold), on three different cell types. This increase is an all-or-nothing type of response that is occurring for threshold values comprised between 1.3 and 2.6 W/kg for the delivered EMF powers and between 1.1 and 1.5 V/cm for the electric fields intensities depending upon the cell type. The electric component of these EMFs is shown to be responsible for the observed increase. Variations of frequency or pulse duration of the electric pulses are shown to be without effect. Thus, EMF, via their electrical component, can perturb one of the most fundamental physiological functions of the cells-endocytosis.

Animals↗
PubMedDate not supplied

Biological effects of low frequency electromagnetic fields.

Epidemiological studies since 1979 have raised some medical and much public concern that low frequency electromagnetic fields, such as those of power-lines and in domestic and industrial electrical wiring, may have harmful biological effects. These studies are generally inconsistent, inconclusive, and difficult to replicate. Identifying biological mechanisms by which such harmful effects may occur has proved difficult, although there are several new and promising approaches. In epidemiological and laboratory studies much greater co-ordination and standardization is needed if greater scientific knowledge of these phenomena, as opposed to mere diverse speculation, is to be achieved.

Electromagnetic Fields↗
PubMed1996

Annals of conflicting results: looking back on electromagnetic field research.

Few environmental health issues are as contentious as the question of whether exposure to electromagnetic fields (EMFs) from power lines increases cancer risk. Among the many actors in this controversy, epidemiologists have played the leading role in raising the question and motivating research. Epidemiologic studies of the effects of exposure to power-line EMFs include the investigation by Dr. Gilles Thériault and colleagues into incidence rates of cancer among electric-utility workers in Quebec, Ontario and France. With the development of personal dosimeters to measure exposure to electric, magnetic and pulsed EMFs, occupational studies in the 1990s have made an important methodologic advance. But, as Thériault explains, improvements in assessing exposure have not yet translated into clear and consistent findings.

Canada↗
PubMed2006

Electromagnetic fields and female breast cancer.

The possibility that long term exposure to relatively weak power frequency electromagnetic fields (EMF) could increase the risk of breast cancer has been investigated during the past decade. The hypothesis is based on the assumption that magnetic field exposures suppress melatonin production and that melatonin is protective against breast cancer. Most epidemiological studies have indicated little or no overall effect of EMF exposure, but some early studies suggested effects among premenopausal women, particularly for estrogen receptor positive breast tumors. The early studies were often limited by small numbers, crude exposure information and lack of information on confounding factors. In more recent occupational studies, again no overall risk increases were reported, but some studies found increased risks in certain subgroups, although with no consistent pattern across studies. A recent very large occupational study with improved exposure assessment and enough statistical power also for subgroup analyses found no indications of increased risks in any subgroups. Most of the recent well-designed residential studies report no increased risks, and similar findings are reported in the majority of studies of bed heating devices. Overall, the weight of the evidence available today does not suggest an increased risk of breast cancer related to EMF exposure.

Breast Neoplasms↗
PubMed2001

Extremely low frequency electromagnetic fields and heat shock can increase microvesicle motility in astrocytes.

The effect of extremely low frequency electromagnetic fields (EMF) on microvesicles was examined in rat astrocytes by video-enhanced microscopy in combination with a perfusable cell chamber. The EMF effect was compared with the effect of heat shock (HS) and with a combination of them both. The velocity of microvesicles was measured using image processing software (NIH Scion image 1.61). After exposure of astrocytes to EMF (50 Hz, 100microT, 1 h), the velocity of microvesicles in astrocytes increased from 0.32 +/- 0.03 microm/s (n = 120, 95% CI) in the untreated control group to 0.41 +/- 0.03 microm/s (n = 175, 95% CI). Fifteen minutes after HS (45 degrees C, 10 min) the microvesicles showed a velocity of 0.56 +/- 0.03 microm/s (n = 125, 95% CI). Combination of HS and EMF led to an increase in velocity up to 0.54 +/- 0.03 microm/s (n = 110, 95% CI). No significant difference between HS and HS+EMF was found. Compared to the untreated control group, the increased microvesicle velocity of the exposed cells might be a stress response of the cell. It is possibly a sign of intensified intracellular traffic required to adjust the metabolic needs.

Animals↗
PubMed1997

Pulsed electromagnetic fields preserve proteoglycan composition of extracellular matrix in embryonic chick sternal cartilage.

The influence of pulsed electromagnetic fields (PEMF) on proteoglycan composition in cartilage extracellular matrix has been investigated. Day 16 embryonic chick sternal cartilage was explanted to culture and exposed for 3 h per day for 2 days to a repetitive single-pulse PEMF with frequency of 15 Hz and peak magnetic field of 1.25 G. PEMF treatment did not affect cell proliferation, as indicated by [3H]thymidine incorporation, but significantly stimulated the retention of glycosaminoglycans in the explants and reduced the release of glycosaminoglycans into the media. Determination of incorporation of [35S]sulfate and [3H]N-acetylglucosamine into proteoglycans in vitro and breakdown of in ovo labelled [35S]sulfated proteoglycans in vitro showed that PEMF treatment significantly suppressed the synthesis of proteoglycans and the degradation of both newly synthesized and pre-existing proteoglycans. Sepharose CL-2B chromatography demonstrated that PEMF did not affect either the size distribution of newly synthesized and pre-existing [35S]sulfated proteoglycans or their ability to aggregate with hyaluronate. Sepharose CL-6B chromatography followed by cellulose acetate electrophoresis revealed that the chain length and degree of sulfation of [35S]sulfated glycosaminoglycans were identical in control and PEMF-treated cultures. It is concluded that PEMF treatment preserved extracellular matrix integrity of cultured cartilage explants by down-regulating proteoglycan synthesis and degradation in a co-ordinated manner without affecting their gross structural nature.

Animals↗
PubMed2002

Effect of intermittent and continuous exposure to electromagnetic fields on cultured hippocampal cells.

This study was designed to assess the effect of 50 Hz electromagnetic fields (EMFs) on hippocampal cell cultures in the presence or absence of either sodium nitroprusside (SNP, a NO donor) or Fe2+ induced oxidative stress. One week old cultured rat hippocampal cells were exposed to either intermittent EMFs (IEMFs, 50 Hz, 0-5 mT, 1 min ON/OFF cycles, repeated 10 times every 2 h, 6 times/day during 48 h) or continuous EMFs (CEMFs, 50 Hz, 0-5 mT for 48 h). In a second set of experiments, the effect on such EMFs applied in combination with oxidative stress induced by 0.5 microM Fe2+ or SNP was estimated. At the end of both sets of experiments, cell mortality was assessed by lactate dehydrogenase measurements (LDH). Neither type of exposure to EMFs was observed to modify the basal rate of cell mortality. The exposure to CEMFs in presence of either NO or Fe2+ did not induce any significant increase in cell death. However, when cells were exposed to EMFs in the presence of NO, we observed a significant increase in cell death of 11 and 23% (P<0.001) at 2.5 and 5 mT, respectively. This effect had some specificity because IEMFs did not modify the effect of Fe2+ on cell mortality. Although the effects of IEMFs reported in this study were only observed at very high intensities, our model may prove valuable in trying to identify one cellular target of EMFs.

Cell Death↗
PubMedDate not supplied

Effect of a pulsing electromagnetic field on metabolically derived osteoporosis in rats: a pilot study.

The literature suggests that a pulsating electromagnetic field (PEMF) is effective against bone loss in disuse osteoporosis. This study was conducted to evaluate the effects of PEMF on metabolically derived osteoporosis in rats. Sixteen 5 month old female Sprague-Dawley rats were divided into three groups (G-1,2,3). G-1 was given a normal diet and no exposure to PEMF; G-2,3 were oophrectomized and fed a low calcium diet for 8 months; and G-3 was also exposed for 24 hr/day to PEMF generated by applying a 15 Hz, 5.6 A peak to peak square wave to Helmholtz coils (64 cm I.D., 200 turns/coil). The rats were sacrificed at 4, 6, and 8 months. Skeletal changes were analyzed by measurements of acid extracted bone calcium and bone mineral content (BMC) using single photon absorptiometry (SPA). Although all animals started at approximately the same weight (mean of 290.0 g), G-2 showed a more progressive increase. While the mean weight after 8 months in G-1 was 350.0 g, and 352.5 g for G-3, that in G-2 was 400.0 g. The calcium content of the femur in G-2 and G-3 at 8 months was lower than that of G-1, but there were no significant differences among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Electromagnetic field effects on cells of the immune system: the role of calcium signaling.

During the past decade considerable evidence has accumulated demonstrating that nonthermal exposures of cells of the immune system to extremely low-frequency (ELF) electromagnetic fields (< 300 Hz) can elicit cellular changes that might be relevant to in vivo immune activity. A similar responsiveness to nonionizing electromagnetic energy in this frequency range has also been documented for tissues of the neuroendocrine and musculoskeletal system. However, knowledge about the underlying biological mechanisms by which such fields can induce cellular changes is still very limited. It is generally believed that the cell membrane and Ca(2+)-regulated activity is involved in bioactive ELF field coupling to living systems. This article begins with a short review of the current state of knowledge concerning the effects of nonthermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells and then closely examines new results that suggest a role for Ca2+ in the induction of these cellular field effects. Based on these findings it is proposed that membrane-mediated Ca2+ signaling processes are involved in the mediation of field effects on the immune system.

Animals↗
PubMed2006

Consultations in primary care for symptoms attributed to electromagnetic fields--a survey among general practitioners.

BACKGROUND: Five percent of the Swiss population attribute symptoms to electromagnetic fields (EMF). General practitioners (GPs) might play a key role in recognising an emerging health risk, since they are the first to observe and follow up persons who attribute symptoms to EMF. It is unclear to what extent EMFs have become an issue in general practice and which experiences GPs report from the consultations. METHODS: We conducted telephone interviews in a random sample of GPs in Switzerland in order to assess the frequency of consultations in primary care due to EMF and the GPs' experience with these patients. RESULTS: 342 general practitioners were interviewed, corresponding to a response rate of 28.2%. 69% of the GPs reported at least one consultation due to EMF, but GPs with a certificate in complementary medicine were much more likely to report EMF consultations. The median of EMF consultation numbers within one year was three. An overview of the most recent EMF-related consultation per GP yielded sleep disorders, headaches and fatigue as the most often reported symptoms and mobile phone base stations, power lines and the own use of mobile phones as the main EMF sources suspected to be associated to symptoms. GPs judged the association between EMF and the symptoms to be plausible in 54% of the cases. There was no combination of symptoms and EMF sources that was remarkably and consistently judged to be a plausible cause of the symptoms. CONCLUSION: In our survey, GPs often judged the association between the health problems and the suspected exposure to be plausible. This plausibility assessment seems to be based on grounds of preventive positions in a situation of scientific uncertainty. More research effort is needed to obtain more insight on a potential association between long term EMF exposure and unspecific symptoms.

Anxiety↗
PubMed2001

Effect of a wound healing electromagnetic field on inflammatory cytokine gene expression in rats.

In earlier studies, we have shown that pulsed electromagnetic fields (PEMFs) induce programmed cell death in cultured T cells and that rats exposed in vivo to PEMFs have decreased T-cell proliferative capacity. These data led us to hypothesize that PEMFs might be used to control proliferation of inflammatory lymphocytes and therefore beneficially affect inflammatory diseases. Tendinitis is characterized by painful inflammation of the tendon. Inflammation is characterized by massive infiltration of T lymphocytes, neutrophils and macrophages into the damaged tissue. These inflammatory cells produce a variety of cytokines, which are the cellular regulators of inflammation. The current study tests whether in vivo PEMF effects are mediated via systemic cytokine production in rat tendinitis. Inflammation was chemically induced in female Harlan Sprague Dawley rats Achilles' tendons and a wound healing PEMF (Electrobiology, Inc.) was applied for 4 hours immediately following injury. Spleens from control and experimental animals were harvested 24 hours later and total RNA was extracted from the tissues. Gene expression was analyzed by reverse transcription of mRNA, and polymerase chain reaction amplification (RT-PCR) using primers specific for the cytokines IFN-gamma, IL-1 beta, IL-6, TNF-alpha, and TGF-beta, as well as for the control beta-actin. RT-PCR products were separated on 1.5% agarose gels and band intensities were normalized to beta-actin gene expression of the same sample. TGF-beta was the only cytokine produced at high levels in rats with tendinitis in comparison to the other cytokines. PEMFs did not show an effect on any cytokine expression in the spleens, 24 hours after induction of tendinitis. Further studies need to test if cumulative exposures of PEMFs are able to regulate inflammatory cytokine expression either at the site of inflammation or at the local lymph nodes.

Achilles Tendon↗
PubMed2003

Effects of high frequency electromagnetic fields on micronucleus formation in CHO-K1 cells.

To investigate the effects of high frequency electromagnetic fields (HFEMFs), we assessed the frequency of micronucleus (MN) formation induced by chromosomal breakage or inhibition of spindles during cell division in Chinese hamster ovary (CHO)-K1 cells, using the cytokinesis block micronucleus method. The MN frequency in cells in the inner, middle and outer wells of an annular culture plate was determined for the following four conditions: (1) CHO-K1 cells were exposed to a HFEMF for 18 h at average specific absorption rates (SARs) of 13, 39 and 50 W/kg with input power 7.8 W, and were compared with a sham-exposed control; (2) the cells were also exposed to a HFEMF at SARs of 78 and 100 W/kg with input power 13 W, and were compared with a sham-exposed control; (3) the cells were treated with bleomycin alone or with bleomycin followed by exposure to a HFEMF for 18 h at SARs of 25, 78 and 100 W/kg, and were compared with a bleomycin-treated positive control. The cells treated with bleomycin alone were compared with sham-exposed controls; and (4) As a high temperature control, CHO-K1 cells were incubated at 39 degrees C for 18 h. In study (1), the MN frequency of cells exposed to a HFEMF at a SAR of up to 50 W/kg was not different to that in sham-exposed cells. In study (2), there were statistically significant increases in the MN frequencies of cells in the middle and outer wells of the annular culture plate caused by exposure to a HFEMF at 100 and 78 W/kg, respectively. In study (3), the MN frequencies of cells in the middle (100 W/kg) and outer wells (78 W/kg) of the annular culture plate were statistically higher than that caused by bleomycin-treatment alone. In study (4), there was a statistically significant increase of MN frequency in the cells treated by heat at 39 degrees C. These results indicate that cells exposed to a HFEMF at a SAR of 78 W/kg and higher form MN more frequently than sham-exposed cells, while exposure to a HFEMF at up to 50 W/kg does not induce MN formation. In addition, a HFEMF at a SAR of 78 W/kg and higher may potentiate MN formation induced by bleomycin-treatment.

Animals↗
PubMed1979

Relation between suicide and the electromagnetic field of overhead power lines.

Laboratory studies have shown that electromagnetic fields similar to those from high-voltage transmission lines can produce biological effects. Surveys of the actual effects of such lines on exposed individuals usually have been hampered by complicating factors tending to blur the data. By means of a new approach, however, correlation has been established between the presence of transmission-line fields and the occurrence of suicides in part of the Midlands of England.

Adolescent↗
PubMed1982

Error sources affecting thermocouple thermometry in RF electromagnetic fields.

Thermocouple thermometry errors in radiofrequency (typically 13, 56 MHZ) electromagnetic fields such as are encountered in hyperthermia are described. RF currents capacitatively or inductively coupled into the thermocouple-detector circuit produce errors which are a combination of interference, i.e., 'pick-up' error, and genuine rf induced temperature changes at the junction of the thermocouple. The former can be eliminated by adequate filtering and shielding; the latter is due to (a) junction current heating in which the generally unequal resistances of the thermocouple wires cause a net current flow from the higher to the lower resistance wire across the junction, (b) heating in the surrounding resistive material (tissue in hyperthermia), and (c) eddy current heating of the thermocouple wires in the oscillating magnetic field. Low frequency theories are used to estimate these errors under given operating conditions and relevant experiments demonstrating these effects and precautions necessary to minimize the errors are described. It is shown that at 13.56 MHz and voltage levels below 100 V rms these errors do not exceed 0.1 degrees C if the precautions are observed and thermocouples with adequate insulation (e.g., Bailey IT-18) are used. Results of this study are being currently used in our clinical work with good success.

Diathermy↗
PubMed1991

[Effect of pulsed electromagnetic field on orthodontic tooth movement through transmission electromicroscopy].

This experiment is to observe the effect of pulsed electromagnetic field (PEMF) on orthodontic tooth movement of guinea pigs through transmission electron microscope (TEM). 14-days observations indicate that PEMF could accelerate the rate of orthodontic tooth movement as a result of the increase in quantity of active cell without changing the ultrastructures of cells and have no unfavorable effects on periodontal tissues.

Animals↗
PubMed2005

Evaluation of spermatogenesis and fertility in F1 male rats after in utero and neonatal exposure to extremely low frequency electromagnetic fields.

AIM: To determine whether in utero and neonatal exposure to a 60 Hz extremely low frequency electromagnetic field (EMF) results in spermatotoxicity and reproductive dysfunction in the F1 offspring of rats. METHODS: Age-matched, pregnant Sprague-Dawley rats were exposed continuously (21 h/day) to a 60 Hz EMF at field strengths of 0 (sham control), 5, 83.3 or 500 microT from day 6 of gestation through to day 21 of lactation. The experimentally generated magnetic field was monitored continuously (uninterrupted monitoring over the period of the study) throughout the study. RESULTS: No exposure-related changes were found in exposed or sham-exposed animals with respect to the anogenital distance, preputial separation, testis weight, testicular histology, sperm count, daily sperm production, sperm motility, sperm morphology and reproductive capacity of F1 offspring. CONCLUSION: Exposure of Sprague-Dawley rats to a 60 Hz EMF at field strengths of up to 500 microT from day 6 of gestation to day 21 of lactation did not produce any detectable alterations in offspring spermatogenesis and fertility.

Animals↗