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At least 973 records · Page 54Linked to original sources
PubMed2004

Absence of genotoxicity in human blood cells exposed to 50 Hz magnetic fields as assessed by comet assay, chromosome aberration, micronucleus, and sister chromatid exchange analyses.

In the past, epidemiological studies indicated a possible correlation between the exposure to ELF fields and cancer. Public concern over possible hazards associated with exposure to extremely low frequency magnetic fields (ELFMFs) stimulated an increased scientific research effort. More recent research and laboratory studies, however, have not been able to definitively confirm the correlation suggested by epidemiological studies. The aim of this study was to evaluate the effects of 50 Hz magnetic fields in human blood cells exposed in vitro, using several methodological approaches for the detection of genotoxicity. Whole blood samples obtained from five donors were exposed for 2 h to 50 Hz, 1 mT uniform magnetic field generated by a Helmholtz coil system. Comet assay, sister chromatid exchanges (SCE), chromosome aberrations (CA), and micronucleus (MN) tests were used to assess DNA damage, one hallmark of malignant cell transformation. The effects of a combined exposure with X-rays were also evaluated. Results obtained do not show any significant difference between ELFMFs exposed and unexposed samples. Moreover, no synergistic effect with ionizing radiation has been observed. A slight but significant decrease of cell proliferation was evident in ELFMFs treated samples and samples subjected to the combined exposure.

Adult↗
PubMed2004

Low electromagnetic field (50 Hz) induces differentiation on primary human oral keratinocytes (HOK).

This work concerns the effect of low frequency electromagnetic fields (ELF) on biochemical properties of human oral keratinocytes (HOK). Cells exposed to a 2 mT, 50 Hz, magnetic field, showed by scanning electron microscopy (SEM) modification in shape and morphology; these modifications were also associated with different actin distribution, revealed by phalloidin fluorescence analysis. Moreover, exposed cells had a smaller clonogenic capacity, and decreased cellular growth. Indirect immunofluorescence with fluorescent antibodies against involucrin and beta-catenin, both differentiation and adhesion markers, revealed an increase in involucrin and beta-catenin expression. The advance in differentiation was confirmed by a decrease of expression of epidermal growth factor (EGF) receptor in exposed cells, supporting the idea that exposure to electromagnetic field carries keratinocytes to higher differentiation level. These observations support the hypothesis that 50 Hz electromagnetic fields may modify cell morphology and interfere in differentiation and cellular adhesion of normal keratinocytes.

Actins↗
PubMed2002

Long-term exposure of male and female mice to 50 Hz magnetic field: effects on fertility.

The effect of an extremely low frequency (ELF) magnetic field on the fertility of adult male and female Swiss mice was investigated. Adult male and female mice were exposed to a 50 Hz sinusoidal magnetic field at approximately 25 microT (rms) for 90 days before they were mated with unexposed counterparts. There were no exposure related effects on the fertility of male or female mice. The number of implantation sites, viable fetuses, and the total number of resorptions were not significantly affected in females impregnated by males exposed to the 50 Hz magnetic field as compared with the control group. The number of implantation sites, viable fetuses and the total number of resorptions in exposed females were also not statistically different from the control group. There were no significant effects on the weights of the testes, seminal vesicles, preputial gland or body weights of males exposed to 50 Hz magnetic field. Furthermore, body and uterine weights were not affected in females exposed to 50 Hz field; however, ovarian weight was significantly increased in females exposed to the same field. These results suggest that exposure of male and female mice to low frequency magnetic field had no adverse effects on fertility and reproduction in mice.

Animals↗
PubMed2004

Extremely low frequency-modulated static magnetic fields to treat cancer: A pilot study on patients with advanced neoplasm to assess safety and acute toxicity.

Results of a toxicity pilot human study approved by the competent ethical Committee are reported. Eleven patients with heavily pre-treated advanced cancer were enrolled in a pilot study with different schedules of time exposure to static magnetic fields (MF), amplitude modulated by ELF. An area including the neck, thoracic and abdomen was MF exposed daily, 5 days/week for 4 weeks according to two different schedules: 20 min daily (4 patients) and 70 min daily (7 patients). ECOG performance status was 1 (2 patients), 2 (8 patients), 3 (1 patient). Toxicity was assessed according to WHO criteria. ECG, Chest X-ray, physical examination, blood cell count and complete blood chemistry were performed before and at the end of the treatment. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) elevation (grade 2 toxicity) in 1 patient and microscopic urinary abnormalities in 5 patients were the only negative effects observed. We conclude that MF can be safely administrated according to the MF exposure schedules.

Dose Fractionation, Radiation↗
PubMed2004

Effects of extremely low frequency electromagnetic fields on the adenylate kinase activity of rod outer segment of bovine retina.

Extremely low frequency electromagnetic fields (ELF-EMFs) of 75 Hz with amplitudes above a threshold of about 125 microT have a dramatic effect on the adenylate kinase (AK) activity of the rod outer segment (ROS) membranes. In fact, the ATP production by ROS membranes or by purified disk membranes placed in the field decreased by approximately 54%. The decrease in enzymatic activity was independent of the time of exposure to the field and was completely reversible. When disk membranes were solubilized with Triton or a soluble isoform of AK was used, negligible effects of the field were obtained on the enzymatic activity, suggesting that the membrane has an important role in determining the conditions for the enzyme inactivation.

Adenosine Triphosphate↗
PubMed2004

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

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

Electromagnetic Fields↗
PubMed2004

No influence of 20 and 400 microT, 50 Hz magnetic field exposure on cognitive function in humans.

The aim of the present study was to investigate cognitive effects of a continuous, vertical extremely low frequency (ELF) magnetic field (MF) of 20 and 400 microT 50 Hz in healthy young men during performance on cognitive tests. Thirty-two volunteers (20-30 years old, mean 22.6 +/- 2.2 years) participated in this double blind study. The test protocol consisted of a set of tests: divided attention, flexibility, memory updating, digit span, digit span with articulary suppression, and time perception. The total duration of the exposure was 65 min. Participants were assigned four sessions: three conditions in the helmet (sham exposure, 20 and 400 microT) and one condition out of the helmet (to control the expectancy effect). No effect of MF exposure was observed on performance.

Adult↗
PubMed2004

Evaluation of genotoxic effect of low level 50 Hz magnetic fields on human blood cells using different cytogenetic assays.

The question whether extremely low frequency magnetic fields (ELFMFs) may contribute to mutagenesis or carcinogenesis is of current interest. In order to evaluate the possible genotoxic effects of ELFMFs, human blood cells from four donors were exposed in vitro for 48 h to 50 Hz, 1 mT uniform magnetic field generated by a Helmholtz coil system. Comet assay (SCGE), sister chromatid exchanges (SCE), chromosome aberrations (CAs), and micronucleus (MN) test were used to assess the DNA damage. ELF pretreated cells were also irradiated with 1 Gy of X-ray to investigate the possible combined effect of ELFMFs and ionizing radiation. Furthermore, nuclear division index (NDI) and proliferation index (PRI) were evaluated. Results do not evidence any DNA damage induced by ELFMF exposure or any effect on cell proliferation. Data obtained from the combined exposure to ELFMFs and ionizing radiation do not suggest any synergistic or antagonistic effect.

Adult↗
PubMed2005

Absence of daytime 50 Hz, 100 microT(rms) magnetic field or bright light exposure effect on human performance and psychophysiological parameters.

The purpose of this study was to reproduce and extend two earlier studies of the effects of human exposure to 50 Hz magnetic fields (MF). In a recent paper, we described results of two double-blind investigations performed to examine effects of 100 microT(rms) 50 Hz MF exposure on psychological parameters in the same group of healthy human volunteers. In each exposure session, at 1 week intervals, with sham, continuous, and intermittent (15 s ON/OFF cycles) MF conditions, mood ratings, performance measures, and electrophysiological measures were taken. In the first study, significant amplitude changes were observed in the event-related brain potentials (ERP) recorded during a dichotic listening task. In the second study, latency and reaction time (RT) slowing were seen on a visual discrimination task (P(300) paradigm). Although these results were little related to the number of parameters analysed, they indicate that low level 50 Hz MF might have a slight influence on ERP and RT under specific circumstances of sustained attention. Before concluding that moderately strong MF exposure can influence cognitive function, previous results should be replicated, using the same paradigms with another group of healthy volunteers. In the present study, 18 healthy subjects were exposed to three experimental sessions of 30 min each, given at 1 week intervals. The sessions consisted of continuous 100 microT(rms) 50 Hz MF exposure, sham condition, and bright light (5000 lux) exposure. The study was performed double-blind, with the exposure order counter-balanced. The data on mood, ERP, RT, and other performance measures did not show any differences among the sham exposure, light exposure, and MF exposure conditions. The results of this study do not support the hypothesis that extremely low frequency (ELF) MF exposure affects the brain's electrical activity or cognitive function at field strength (100 microT(rms)) similar to that found in very close proximity of some household and industrial electrical appliances and well in excess of the average MF strength (c. 0.1 microT) found in homes. The sensitivity of the experiment was possibly not sufficient to detect an effect at this relatively low MF, and larger sample sizes would be required in further studies.

Adult↗
PubMed2005

Central nervous system tumours in children: epidemiology and risk factors.

In children, a variety of distinct tumour types arise in the central nervous system (CNS) but they are frequently considered by epidemiologists as a single entity. CNS tumours are the second most common childhood malignancy and occur more frequently in developed countries than developing nations. Approximately 50% of paediatric CNS tumours are gliomas, with astrocytomas of the piloctyic type predominating. Distributions of subtypes by age show that primitive neuroectodermal tumours (PNET) and ependymomas mainly occur in children less than 10 years. There is an ongoing debate with regard to the apparent increases in incidence over recent decades, which, it has been suggested, are accounted for by improved diagnostic technologies implemented in the mid 1980s. CNS tumours differ between children and adults with respect to the proportion of all cancers (20% in children, less than 2% in adults), their cellular origins, classification scheme, the proportions of pathological subtypes, and anatomic site. The causes of childhood CNS tumours are largely unknown; and although an estimated 5% or more may be explained by genetic predisposition, investigations of environmental aetiology have not been fruitful. Whilst high dose ionising radiation is an established risk factor for this group of tumours, reported associations with dietary N-nitroso compounds have not been consistent. Exposure to ELF EMF, at any level, has not been associated with childhood CNS tumours, but the current evidence base is inadequate for complete evaluation. The rarity of childhood CNS tumours necessitates careful attention being paid to the design of future aetiological studies.

Bias↗
PubMed2005

Effect of a low intensity magnetic field on human motor behavior.

Extremely low frequency (ELF) magnetic fields (MF) are omnipresent in our modern daily environment, but their effects on humans are still not clearly established. The aim of this study was to determine the effect of a 50 Hz, 1,000 microT MF centered at the level of the head on human index finger micro-displacements. Twenty-four men recruited among the personnel of the French company, Electricité de France (EDF), completed the experiment. Their postural and kinetic tremors were recorded under four "field-on" and four "field-off" conditions, each tested during a real and a sham sequence. Eight postural and four kinetic tremor characteristics were calculated on recorded time series and were used for statistical analysis. No effect of the MF was found for kinetic tremor. Concerning postural tremor, the proportion of oscillations at low frequencies (between 2 and 4 Hz) was higher during the real than during the sham exposure sequence (P<.05). It suggests that MF could have a subtle delayed effect on human behavior, which is clearly not pathological. These results should be taken into account for the establishment of new exposure limits.

Adult↗
PubMed2005

Analysis of the structure of magnetic fields that induced inhibition of stimulated neurite outgrowth.

The important experiments showing nonlinear amplitude dependences of the neurite outgrowth in pheochromocytoma nerve cells due to ELF magnetic field exposure had been carried out in a nonuniform ac magnetic field. The nonuniformity entailed larger than expected variances in magnetic field magnitudes associated with specific levels of biological effects, thereby evoking a question about validity of the interpretations formulated for the case of a uniform field. In this work, we calculate the relative value of nonuniformity and deviations in ac magnetic field. It is shown that these factors do not affect the main conclusion in the original papers about the form of the amplitude dependence of the observed biological effect.

Animals↗
PubMed2006

A 50 Hz sinusoidal magnetic field does not damage MG-63 three-dimensional tumor spheroids but induces changes in their invasive properties.

The possibility that a sinusoidal 50 Hz magnetic field with a magnetic flux density of 1 mT can damage MG-63 osteosarcoma spheroids and induce variations in the invasive properties of these three-dimensional model systems after 2 days of exposure was investigated. Specifically, possible damage induced by these fields was examined by determining changes in spheroid surface morphology (light microscopy), growth (spheroid diameter and protein content determination), lactate dehydrogenase release, and reduced glutathione amount. Possible changes in the invasive properties were studied by invasion chambers. The results show no induction of cell damage by ELF fields while invasion chamber assays demonstrate a significant increase in the invasive potential of exposed spheroids. In order to determine if the fibronectin or hyaluronan receptors are involved, Western blot analysis was conducted on these two proteins. No significant variations were observed in either receptor in MG-63 multicellular tumor spheroids.

Cell Line, Tumor↗
PubMed2006

Exposure to AC and DC magnetic fields induces changes in 5-HT1B receptor binding parameters in rat brain membranes.

The binding properties of the G-protein coupled receptor (GPCR) serotonin 5-HT1B receptor were studied under exposure to AC (50 and 400 Hz) and DC magnetic fields (MF) in rat brain membranes. This was an attempt at replicating the positive findings of Massot et al. In saturation experiments using [3H]5-HT, 1-h exposures at 1.1 mT(rms) 50 Hz caused statistically significant increases in both the K(D) and B(max) binding parameters, from 1.74 +/- 0.3 to 4.51 +/- 0.86 nM and from 1428 +/- 205 to 2137 +/- 399 CPM, respectively, in good agreement with previous results. Exposure of the membranes at 400 Hz 0.675 mT(rms) did not elicit a larger increase in K(D) in spite of a much larger induced current density. DC fields (1.1 and 11 mT) had a lesser effect compared to AC fields at low values of K(Dsham), but decreased the affinity at higher values of K(Dsham). Modeling of the receptor-ligand-G protein interactions using the extended ternary complex model yielded good fits for all our data and that of Massot et al., showing that the AC field may act by decreasing the ability of the G-protein to alter the ligand-receptor affinity. The hypothesis is that the bipolar nature of the AC field explains the different nature of the effects observed with AC and DC exposures. These findings constitute one of the few documented pieces of evidence for cell-free effects of DC and extremely low frequency (ELF) AC MFs in the mT range.

Animals↗
PubMed2006

50 Hz magnetic fields of constant or fluctuating intensity: effects on immunocyte hsp70 in the mussel Mytilus galloprovincialis.

Effects of a single 30 min exposure to a 50 Hz, 400 microT sinusoidal extremely low frequency magnetic field (ELF MF) on hsp70 expression in immunocytes from the bivalve Mytilus galloprovincialis was investigated using RT-PCR and immunoblot approaches. The results indicate that in M. galloprovincialis immunocytes hsp70 expression was unaltered at both transcriptional and translational level after exposure to constant or fluctuating intensity MFs.

Animals↗
PubMed2006

Childhood leukemia, electric and magnetic fields, and temporal trends.

During the past 25 years concern has been raised about the possible health effects of extremely low frequency (ELF) electric and magnetic fields (EMFs), particularly regarding childhood leukemia. Comparison of changes in electricity consumption (a surrogate for exposure) to changes in childhood-leukemia rates, known as ecologic correlation, have been used to argue both for and against the association between magnetic fields and childhood leukemia. In this paper we explore what can be learned from such an ecologic approach. We first examine separately the evidence on trends in exposure to EMFs and on trends in leukemia rates, and then compare the two. Both incidence rates and exposures have increased, but there are so many approximations and assumptions involved in connecting the two trends that we cannot regard the ecologic evidence as providing any meaningful evidence for or against a causal link.

Acute Disease↗
PubMed1983

Oviposition and development of Drosophila modified by magnetic fields.

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

Drosophila melanogaster↗