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The modifying influence of the weak electromagnetic field on the development of the audiogenic spasmodic activity in rats was shown. The decrease of lifetime of experimental rats exposed to electromagnetic fields with different parameters and development of tumours (in one set of experiments) was found.
There is growing public concern that radio frequency electromagnetic fields may have adverse biological effects. In the present study eight healthy male students were tested to see whether or not radio frequency electromagnetic fields as used in modern digital wireless telecommunication (GSM standard) have noticeable effects on salivary melatonin, cortisol, neopterin, and immunoglobulin A (sIgA) levels during and several hours after exposure. In a specifically designed, shielded experimental chamber, the circularly polarized electromagnetic field applied was transmitted by an antenna positioned 10 cm behind the head of upright sitting test persons. The carrier frequency of 900 MHz was pulsed with 217 Hz (average power flux density 1 W/m2). In double blind trials, each test person underwent a total of 20 randomly allotted 4 hour periods of exposure and sham exposure, equally distributed at day and night. The results obtained show that the salivary concentrations of melatonin, cortisol, neopterin and sIgA did not differ significantly between exposure and sham exposure.
The mechanism whereby low-frequency electromagnetic fields accelerate axonal regrowth and regeneration of peripheral nerve after crush lesion is not known. One candidate is an alteration in axonal transport. In this study we exposed unoperated rats for 15 min/day, and rats that had undergone a crush lesion of the sciatic nerve, for 1 hr/day for 2 days, to 2-Hz pulsed electromagnetic fields. To label fast transported proteins, [3H]-proline was microinjected into the spinal cord, and the sciatic nerves were removed 2, 3.5, and 5 hr later. The rates of fast axonal transport were obtained for animals in all groups by counting sequential 2-mm segments of nerves. The following transport rates were found: in unoperated normal sciatic nerve not exposed to PEMF, 373 +/- 14 mm/day; in unoperated normal nerve exposed to PEMF, 383 +/- 14 mm/day; in sham crush nerves not exposed to PEMF, 379 +/- 19 mm/day; in sham crush nerve exposed to PEMF, 385 +/- 17 mm/day; in crushed nerves not exposed to PEMF, 393 +/- 16 mm/day. and in crushed nerves exposed to PEMF, 392 +/- 15 mm/day. The results of these experiments indicate that 1) a crush injury to the sciatic nerve does not alter the rate of fast axonal transport, and 2) low-frequency pulsed electromagnetic fields do not alter fast axonal transport rates in operated (crush) or unoperated sciatic nerves.
Bearing in mind a great diffusion of electromagnetic fields (EMF) with power-line frequency (in Poland-50 Hz) both in the occupational and communal environments, it is not surprising that possible health effects related to this exposure evoke much interest. Electromagnetic fields may affect the circulatory and nervous systems because of theoretical probability that electric impulses, generated by external electric and magnetic fields, may disturb their functions. For this reason we have decided to evaluate the functioning of the circulatory system in persons occupationally exposed to power-line frequency electromagnetic fields by employing the most up-to-date methods facilitating the in-depth diagnosis of the circulatory system and neurovegetative mechanisms. The work presented focused on the evaluation of electrocardiographic changes. The study covered 63 workers of the transforming and distributing stations, aged 22-67 years (median 39 +/- 10), employed under exposure for 2-43 years (median 15 +/- 10). The control group consisted of 42 workers of radio link stations, aged 23-65 years (median 30 +/- 14), employed in the similar system but not exposed to EMF, with employment duration of 1-42 years (median 13 +/- 4). All persons were subject to general medical examinations, resting ECG, and 24 h Holter monitoring. In addition, the level of exposure in individual workplaces was estimated following the measurements of the intensity of electric and magnetic fields. In workers of electromagnetic stations an increased risk for electrocardiographic disturbances was revealed. Under conditions of exposure to electric fields, observed in stations where workers were employed, the risk was increased by 10%.
AIM: Recently, pulsating electromagnetic fields have gained wide attraction in the treatment of various orthopaedic diseases. The purpose of this study is to evaluate the scientific evidence for the effectiveness of this therapeutic tool. METHOD: All clinical studies which deal with pulsating electromagnetic fields in the treatment of orthopaedic conditions are reviewed. To elucidate the physiological basis of the method, important experimental studies are considered. RESULTS: 37 clinical studies with 3379 patients are evaluated, of which only a minority were performed as prospective studies with control groups. The results of the studies, performed on patients with various orthopaedic conditions, are not unequivocal and partly inconsistent. In view of the physiological basis many questions remain unanswered. CONCLUSIONS: At present the use of pulsating electromagnetic fields in the treatment of orthopaedic diseases is not scientifically proven.
Pulsing electromagnetic fields (PEMFs) induce weak electric currents in bone by external coils on casts or skin. This surgically noninvasive, outpatient method, approved by the Food and Drug Administration in November 1979, produced confirmed end results in 1,007 ununited fractures and 71 failed arthrodeses, worldwide. Overall success at Columbia-Presbyterian Medical Center was 81%; internationally, 79%; and in other patients in the United States, 76%. Treatment with PEMFs was effective in 75% of 332 patients (a subset) with an average 4.7-year disability duration, an average of 3.4 previous operative failures to produce union, and a 35% rate of infection. Eighty-four percent of carpal naviculars and 82% of femoral neck-trochanteric nonunions were united. After attempted arthrodeses could not salvage a failed total-knee prosthesis, PEMFs promoted healing in 85% of patients. When coils were unsuccessful alone, combining them with surgical repair was effective.
The purpose of this study was to determine whether the application of either samarium cobalt magnets or pulsed electromagnetic fields could increase the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the effect of a magnetic field on bony physiology and metabolism and to monitor for possible systemic side effects. Fifteen grams of laterally directed orthodontic force were applied to move the maxillary central incisors of a sample of 18 young male Hartley guinea pigs divided into three groups: group 1, an orthodontic coil spring was used to move the incisors; group 2, a pair of samarium-cobalt magnets provided the tooth moving force; and group 3, a coil spring was used in combination with a pulsed electromagnetic field. The results showed that both the static magnetic field produced by the samarium-cobalt magnets and the pulsed electromagnetic field used in combination with the coil spring were successful in increasing the rate of tooth movement over that produced by the coil springs alone. The mechanism producing this effect appears to have involved a reduction in the "lag" phase often seen in orthodontic tooth movement. Both magnetically stimulated groups also showed increases in both the organization and amount of new bone deposited in the area of tension between the orthodontically moved maxillary incisors.
The electromagnetic field focusing system is capable of sharply focusing induced current resulting in pinpoint heating of tissue. This heat can cut and vaporize tissue while simultaneously coagulating vessels. This is a report on the first 15 consecutive neurosurgical cases where this system was used for tumor excision. The system was found to be an effective and safe surgical tool. It functioned effectively, even under saline and cerebrospinal fluid and through narrow openings during stereotactic microsurgical procedures.
An exposure system consisting of two long transversal electromagnetic (TEM) cells, operating at a frequency of 900 MHz, is presented and discussed. The set-up allows simultaneous exposure of a significant number of animals (up to 12 mice per cell) in a blind way to a uniform plane wave at a frequency of 900 MHz, for investigating possible biological effects of exposure to electromagnetic fields produced by wireless communication systems. A heating/refrigerating system has also been designed for maintaining comfortable environmental conditions within the TEM cells during experiments. An accurate dosimetric study has been performed both numerically and by means of direct measurements on phantoms and living mice. The results have shown that good homogeneity of exposure and adequate power efficiency, in terms of whole-body specific absorption rate (SAR) per 1 W of input power, are achievable for the biological target.
We studied the effect of symmetric, biphasic sinusoidal electromagnetic fields (EMF) (20 Hz, 6 mT) on the differentiation of normal human skin fibroblasts (HH-8), normal human lung fibroblasts (WI38), and SV40-transformed human lung fibroblasts (WI38SV40) in in vitro cultures. Cells were exposed up to 21 days for 2 x 6 h per day to EMF. Normal mitotic human skin and lung fibroblasts could be induced to differentiate into postmitotic cells upon exposure to EMF. Concomitantly, the synthesis of total collagen as well as total cellular protein increased significantly by a factor of 5-13 in EMF-induced postmitotic cells. As analyzed by two-dimensional gel electrophoresis of [35S]methionine-labeled polypeptides, EMF-induced postmitotic cells express the same differentiation-dependent and cell type-specific marker proteins as their spontaneously arising counterparts. In SV40-transformed human lung fibroblasts (cell line WI38SV40) the exposure to EMF induced the differentiation of mitotic WI38SV40 cells into postmitotic and degenerating cells in subpopulations of WI38SV40 cell cultures. Other subpopulations of WI38SV40 cells did not show any effect of EMF on cell proliferation and differentiation. These results indicate that long-term EMF exposure of fibroblasts in vitro induces the differentiation of mitotic to postmitotic cells that are characterized by differentiation-specific proteins and differentiation-dependent enhanced metabolic activities.
BACKGROUND: Due to the ubiquitous use of cellular phones much has been speculated on secondary effects of electromagnetic irradiation emitted by those. Additionally, several studies have reported vegetative alterations as well as effects on the neuronal and molecular levels in humans. Here, using a psycho-physiological test paradigm, we examined effects of exposure to pulsed electromagnetic fields on cognitive performance. MATERIALS AND METHODS: In 11 volunteers, we tested cognitive processing under field exposure (GSM standard) and under field-free conditions. To examine the hypothesized effect of pulsed fields, we applied an auditory discrimination task and determined the participant's current 'Order Threshold' value. Following a first test cycle, the volunteers had to relax for 50 min while being, or not, exposed to pulsed electromagnetic fields. Subsequently, the test was repeated. Data acquired before and after the resting phase were compared from both experimental conditions. RESULTS: We found that nine of the 11 test participants (81.8%) showed worse results in their auditory discrimination performance upon field exposure as compared with control conditions. Group data comparison revealed a statistical significance of P = 0.0105. CONCLUSION: We could show that the participants' cognitive performance was impaired after exposure to pulsed electromagnetic fields. With regard to this finding, we recommend that the use of cellular phones should be restricted generally and in particular in respect of physical hazard of high-risk groups, e.g. elderly, children and ill people.
The current study was designed to evaluate the properties of thermosensitive magnetoliposomes (TMs), a new drug carrier proposed by the authors, in an electromagnetic field pertaining to their selective heating and drug release under an in vivo condition. TMs containing 5-fluorouracil (5-FU) were prepared by reverse-phase evaporation, injected into the tumor mass of B 16-BL6 melanoma in mice, and selectively heated by a 500-kHz electromagnetic field. The release profile of 5-FU from TMs was examined by using a microdialysis technique. The temperature of TMs in the tumor was effectively elevated to 42 degrees C and maintained at this temperature, overcoming the "cooling effect" of blood flow and surrounding tissues. The release kinetics of 5-FU from TMs was successfully analyzed by physiological modeling, which allows the prediction of intratumor drug concentrations during electromagnetic field exposure under various conditions. In conclusion, this study first demonstrated an in vivo evidence for the electromagnetic field-induced thermosensitive release of a drug from TMs in a tumor with the use of microdialysis.
The adverse effect of cigarette smoking on human spines has been noted indirectly. There is correlation of increased back pain among individuals who smoke heavily. The hypothesis of this study was that an environment of cigarette smoking is an adverse event and will create a reduced pH in the rabbit intervertebral disc. Electromagnetic fields, however, can defend against this adverse event and reduce the tendency toward acidic pH. Rabbits were exposed to cigarette smoke for 2, 4, or 6 weeks and their intradiscal pH measured. Cigarette-smoke-exposed discs demonstrated a consistently lower pH than did the discs of the machine control rabbits. The second group of rabbits were exposed to cigarette smoke and pulsed electromagnetic fields. The cigarette-smoke-exposed rabbits that were exposed to the pulsed electromagnetic fields for 4 hr/day demonstrated no change in their intradiscal pH, in contrast to those who were exposed to smoke alone. In conclusion, cigarette smoke exposure in rabbits consistently produces a lower intradiscal pH and pulsed electromagnetic fields can defend against this adverse effect.
In an attempt to approach the mechanism of action of pulsed electromagnetic fields (PEMF) on biological systems, the effects on protein synthesizing activity and on membrane transport have been examined in rat skin. PEMF characterized by specific physical parameters stimulate the incorporation of L-[U-14C]isoleucine into the proteins of rat skin as well as the alpha-amino[1-14C]isobutyric acid uptake during incubation in buffer medium with extracellular electrolyte composition. Analogous incubation experiments carried out in an intracellular medium results in an inhibitory effect of PEMF on both biological functions. Addition of 10(-3) M ouabain to the incubation medium, partially blocking the Na+/K+-ATPase pump mechanism, apart from reducing amino acid transport, results in an overall disappearance of any stimulatory effects by PEMF. PEMF applied to the skin in the presence of 10(-3) M 2,4-dinitrophenol uncoupling the oxidative phosphorylation in the mitochondria and seriously restricting protein synthesis, still provides a limited stimulatory effect on protein synthesizing activity and on membrane transport. The effects of PEMF may well be understood by an increased availability of precursor elements controlled at the cell membrane level. Indeed the observed effects may even be simulated outside electromagnetic fields by modifications in the electrolyte composition of the incubation medium.
Since Wertheimer and Leeper reported in 1979 that children living near power distribution lines have as high as twice or three times the incidence of cancer, the relation of leukemia or cancer to extremely-low-frequency (ELF) electromagnetic field (EMF) has been a subject of repeated argument. We cannot sum up the bioeffects of EMF in a few words, for these are attributed to frequency difference. This review discusses the bioeffects of EMF ranging from frequency of microwave to static magnetic field with main stress on the socalled non-thermal effects below radiofrequency band. Non-thermal effects are rather weak compared with those of high frequency band and have been treated as unknown matter for a long period. However, as the EMF energy has come to be increasingly used at high levels, we can now clearly detect the bioeffects of induced eddy currents. On the other hand, some findings about low level ELF electromagnetic field suspected as a cancer-promoting factor are mainly gained by epidemiological method. Cancer researchers concerned with recent powerline issues are coming up with many reports on oncological effects of very low-level (0.1 microT order) ELF electromagnetic fields. More data, however, should be collected to reach appropriate conclusion about the possibility of low level ELF electromagnetic fields have an effect of cancer promotion. As for the safety standards of static magnetic field it should be noted that in 1993 National Radiation Protection Board (UK) and International Radiation Protection Association published the highest values ever recommended. These announcements would agree with our assumption that biological processes require high flux density of ELF-EMF proportional to 1/f, where frequency and flux density are indicated with a logarithmic function.
This paper summarizes the published literature and current problems relating to possible cancerogenic effects of occupational and residential exposure to ELF electromagnetic fields at levels slightly above ambient background. There are several suggestions that such an exposure may increase the risk of cancer, but these studies failed to provide conclusive indications. The present state of uncertainty led to a variety of recommendations and statements being made concerning restrictions to the exposure of people to ELF electromagnetic fields. Attempts to detect direct chromosomal damage from ELF electromagnetic fields have proven negative, while results on cancer promotion have been controversial. On the basis of several epidemiological studies on occupational exposure, an increased risk of leukemia, brain cancer and male breast cancer is apparent; the literature on residential exposure provides some evidence of an effect on childhood cancer, especially leukemia; however, when interpreting these results some major methodological concerns should be kept in mind. In conclusion, the public concern and potential public health impact of this environmental agent argue strongly for addressing further research in order to identify mechanisms of action on biological systems, to define the proper assessment of exposure and to obtain good epidemiological evidence.
Two systems for exposing mice to 2,450-MHz electromagnetic fields are described. In a waveguide system, four mice were placed in a Styrofoam cage and exposed dorsally to circularly polarized electromagnetic fields. The temperature and humidity in the mouse holder were kept constant by forced-air ventilation. For 1-W input power to the waveguide, the average specific absorption rate (SAR) was determined by twin-well calorimetry to be 3.60 +/- 0.11 (SE) W/kg in 27-g mice. The maximum SAR at the skin surface determined thermographically was 8.36 W/kg in the head of the mouse. The second system was a miniature anechoic chamber. Six mice were irradiated dorsally to far field plane waves. Copper shielding and high-temperature absorbing material were lined inside the chamber to accommodate the high input power. The air ventilation at the location of the mice was separately controlled so that any heating in the absorber would not affect the animals. For 1-W input power, the average SAR was 0.17 +/- 0.01 W/kg and the maximum SAR at the skin surface was 0.41 W/kg in the animal when irradiated with body axis parallel to the E field; the SARs were 0.11 +/- 0.01 W/kg and 0.64 W/kg, respectively, when irradiated perpendicular to the E field.
Rats were sham exposed or exposed perinatally to a 60-Hz electromagnetic field, 22 days in utero and the first 8 days post partum. Each of the 30 once-daily exposures was 20 h in duration. The electric component of the field was vertical 30 kV/m rms, and the magnetic field component was 100 microTG rms. Later, as adults, male rats were trained to emit an operant response when reinforced with food on a multiple, random-interval schedule. Exposed rats (N = 21) gradually came to respond at significantly lower rates than did sham-exposed controls (N = 20). This finding was confirmed and extended in a second, independently performed experiment. After a sequence including operant conditioning followed by experimental extinction of responding and then by a suspension of conditioning and finally by more than a month of reconditioning, slower rates of responding were found to persist in the adult animals. The evidence of altered behavior several months after combined, fetal-neonatal exposure to an electromagnetic field presents an interesting contrast with other findings: Field-exposed rats did not differ from sham-exposed rats in terms of body mass, physical appearance, grossly observed activity level, or incidence of disease.