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PubMed2002

Electromagnetic field standards in Central and Eastern European countries: current state and stipulations for international harmonization.

Electromagnetic field standards in the West are based on well-established acute biological effects that could be considered as signaling a potentially adverse health effect. The specific absorption rate, which is proportional to the tissue heating (thermal effects), represents the basic restriction of exposure to Radio-Frequency (RF) fields. On the other hand, Eastern European standards are designed to protect from potential non-thermal effects that might be caused by chronic exposure to very low intensities, where a so-called "power load" (a product of field intensity and duration of exposure) represents the basic limitation. Thus, electromagnetic field standards in Eastern European countries differ considerably from those which are proposed by the International Commission of Non-ionizing Radiation Protection and the Standards Coordinating Committee 28 of the Institute of Electrical and Electronics Engineers, Inc. In the present paper, the strategies for development of exposure limit values in electromagnetic fields standards currently in force in Eastern and Central European countries are discussed. Some differences as well as similarities of the national health and safety standards and the main obstacles to harmonization of these standards with those being established by Western national and international organizations and agencies are presented.

Electromagnetic Fields↗
PubMed1988

Occupational and residential 60-Hz electromagnetic fields and high-frequency electric transients: exposure assessment using a new dosimeter.

One problem that has limited past epidemiologic studies of cancer and exposure to extremely low-frequency (0-100 Hz) electric and magnetic fields has been the lack of adequate methods for assessing personal exposure to these fields. A new 60-Hz electromagnetic field dosimeter was tested to assess occupational and residential exposures of a group of electrical utility workers and a comparison background group over a 7-day period. Comparing work periods only, utility workers' exposures were significantly higher than background levels by a factor of about 10 for electric (E) and magnetic (B) fields and by a factor of 171 for high-frequency transient electric (HFTE) fields. When overall weekly time-weighted averages combining work and nonwork exposures were compared, ratios of the exposed to background groups were lower. B and HFTE exposure ratios remained statistically significant, with values of 3.5 and 58, respectively, whereas the electric field exposure ratio was no longer significant, with a value of 1.7. E-field exposures of the background group were the highest during the nonwork period, probably reflecting the use of electrical appliances at home. Residential E- and B-field exposures were in the same range as published results from other surveys, whereas occupational E-field exposures tended to be lower than exposures reported in other studies. The high variability associated with occupational exposures probably accounts for the latter discrepancy. Worker acceptance of wearing the dosimeter was good: 95% of participants found it to be of little or no inconvenience while at work. At home, 37% found the device to be inconvenient in its present form but would not object to wearing a slightly smaller and lighter dosimeter.

Electricity↗
PubMed1996

Exposure to high-frequency transient electromagnetic fields.

OBJECTIVES: The purpose of this study was to assess exposure to high-frequency transient (HFT) electromagnetic fields in occupational and residential environments. METHODS: Exposure to HFT electromagnetic fields was measured with personal dosimeters for 301 volunteers (396 measurements) in periods of 24 h in both occupational and residential environments. The study included electrical utility workers (generation, transmission, distribution, substation), office and industrial workers, and people living near high-power transmission lines. The measure of exposure to HFT fields was specified as the proportion of time (parts per million) in which the electric field exceeds a nominal threshold level of 200 V.m-1 at 5-20 MHz. Recently the specification of the HFT channel of the dosimeter has been found to be incomplete; therefore a testing of the threshold level and the sensitivity to electromagnetic fields from radio-telephones was carried out. RESULTS: The percentage of measurements with a mean workday exposure above 0.1 ppm was 6.5-9.4% for the utility groups and 0.9% for all the nonwork measurements. It is likely that the use of radio-telephones has contributed significantly to the number of HFT events in some of the measurements, especially for the generation workers. The nominal threshold level of the dosimeter was found to vary considerably depending on the polarization of the field (20-400 V.m-1 at 13.56 MHz for one instrument). CONCLUSIONS: Generally speaking, HFT fields appeared infrequently. The workday exposure to HFT fields and 50 Hz magnetic fields ranked the groups differently. There is a need for developing instrumentation for HFT field measurements further.

Denmark↗
PubMed2007

Effects of short- and long-term pulsed radiofrequency electromagnetic fields on night sleep and cognitive functions in healthy subjects.

There has been wide public discussion on whether the electromagnetic fields of mobile telephones and their base stations affect human sleep or cognitive functioning. As there is evidence for learning and memory-consolidating effects of sleep and particularly of REM sleep, disturbance of sleep by radiofrequency electromagnetic fields might also impair cognitive functions. Previously realized sleep studies yielded inconsistent results regarding short-term exposure. Moreover, data are lacking on the effect that short- and long-term exposure might have on sleep as well as on cognitive functions. Therefore, 10 healthy young male subjects were included and nocturnal sleep was recorded during eight consecutive nights. In the second, third, and last night, we investigated polysomnographic night sleep and cognitive functions. After the adaptation and baseline nights, the participants were exposed to a defined radiofrequency electromagnetic field during the following six nights. We analyzed polysomnographic night sleep according to Rechtschaffen and Kales [1968, Manual of Standardized Terminology, Techniques and Scoring System for Sleep of Human Subjects] as well as by power spectra and correlation dimension. Cognitive functions were investigated by an array of neuropsychological tests. Data analysis was done by comparing the baseline night with the first and last exposure night and the first two sleep cycles of the respective nights. We did not find significant effects, either on conventional sleep parameters or on power spectra and correlation dimension, nor were there any significant effects on cognitive functions. With our results, we are unable to reveal either short-term or cumulative long-term effects of radiofrequency electromagnetic fields on night sleep and cognitive functions in healthy young male subjects.

Adult↗
PubMed1998

Initial exploration of pulsing electromagnetic fields for treatment of migraine.

Two studies were conducted during which 23 patients with chronic migraine were exposed to pulsing electromagnetic fields over the inner thigh. In an open study, 11 subjects kept a 2-week headache log before and after 2 to 3 weeks of exposure to pulsing electromagnetic fields for 1 hour per day, 5 days per week. The number of headaches per week decreased from 4.03 during the baseline period to 0.43 during the initial 2-week follow-up period and to 0.14 during the extended follow-up which averaged 8.1 months. In a double-blind study, 9 subjects kept a 3-week log of headache activity and were randomly assigned to receive 2 weeks of real or placebo pulsing electromagnetic field exposures as described above. They were subsequently switched to 2 weeks of the other mode, after which they kept a final 3-week log. Three additional subjects in the blind study inadvertently received half-power pulsing electromagnetic field exposures. The 6 subjects exposed to the actual device first showed a change in headache activity from 3.32 per week to 0.58 per week. The 3 subjects exposed to only half the dose showed no change in headache activity. Large controlled studies should be performed to determine whether this intervention is actually effective.

Adult↗
PubMed1987

[Improvement in the hygienic standards for radio-frequency electromagnetic fields in member countries of the COMECON].

The hygienic norms for radiofrequency electromagnetic fields in this country are based on a large number of experimental and industrial studies performed in separate countries and jointly on the CMEA side. Up to 1983 they comprised the widest frequency range in the world - from 60 kHz, 300 GHz, protecting in the best way man. However, these hygienic norms are not perfect: they have steplike frequency dependence, do not include exposure (except at the length of wave under 1 m - microwave range; there are no norms for frequency under 60 kHz, for magnetic field from 1.5 to 30 MHz and from 50-300 MHz do not concern modulated electromagnetic fields and for their combination with other factors of the environment--noise, vibration, overheated microclimate, some toxic substances etc. Therefore, on the side of CMEA two new standards are under preparation, which include the quantity equivalent dose effect in the microwave range--200 W h/cm2, and also report the exposure of the other ranges. This is an advance in the principles of the hygienic standardization, facilitate the hygiene evaluation and are prepared for implementation in our country for the next 2-3 years.

Electromagnetic Fields↗
PubMed1990

Amplitude windows and transiently augmented transcription from exposure to electromagnetic fields.

The exposure of cells to relatively low-intensity, pulsed, low-frequency electromagnetic fields can result in a transient augmentation of mRNA synthesis. Under certain conditions of irradiation, the augmentation is a function of the strength of the electromagnetic field. A linear, multi-step, chemical-reaction model accounts for many of the principal features that are observed in both the time- and intensity-dependent variations of transcriptional effects. The crucial assumption in the model is that the direct effect of electromagnetic fields on exposed cells is an increase in the rate constant that characterizes one of the intermediate sequential reactions in the synthesis of mRNA.

Electromagnetic Fields↗
PubMed2001

Pulsed electromagnetic fields affect the intracellular calcium concentrations in human astrocytoma cells.

Experiments assessed whether long term exposure to 50 Hz pulsed electromagnetic fields with a peak magnetic field of 3 mT can alter the dynamics of intracellular calcium in human astrocytoma U-373 MG cells. Pretreatment of cells with 1.2 microM substance P significantly increased the [Ca(2+)](i). The same effect was also observed when [Ca(2+)](i) was evaluated in the presence of 20 mM caffeine. After exposure to electromagnetic fields the basal [Ca(2+)](i) levels increased significantly from 143 +/- 46 nM to 278 +/- 125 nM. The increase was also evident after caffeine addition, but in cells treated with substance P and substance P + caffeine we observed a [Ca(2+)](i) decrease after exposure. When we substituted calcium-free medium for normal medium immediately before the [Ca(2+)](i) measurements, the [Ca(2+)](i) was similar to that measured in the presence of Ca(2+). In this case, after EMFs exposure of cells treated with substance P, the [Ca(2+)](i), measured without and with addition of caffeine, declined from 824 +/- 425 to 38 +/- 13 nM and from 1369 +/- 700 to 11 +/- 4 nM, respectively, indicating that electromagnetic fields act either on intracellular Ca(2+) stores or on the plasma membrane. Moreover the electromagnetic fields that affected [Ca(2+)](i) did not cause cell proliferation or cell death and the proliferation indexes remained unchanged after exposure.

Astrocytoma↗
PubMed1998

Effects of electromagnetic fields in experimental fracture repair.

The clinical benefits of electromagnetic fields have been claimed for 20 centuries, yet it still is not clear how they work or in what circumstances they should be used. There is a large body of evidence that steady direct current and time varying electric fields are generated in living bone by metabolic activity and mechanical deformation, respectively. Externally supplied direct currents have been used to treat nonunions, appearing to trigger mitosis and recruitment of osteogenic cells, possibly via electrochemical reactions at the electrode-tissue interface. Time varying electromagnetic fields also have been used to heal nonunions and to stabilize hip implants, fuse spines, and treat osteonecrosis and osteoarthritis. Recent research into the mechanism(s) of action of these time varying fields has concentrated on small, extremely low frequency sinusoidal electric fields. The osteogenic capacity of these fields does not appear to involve changes in the transmembrane electric potential, but instead requires coupling to the cell interior via transmembrane receptors or by mechanical coupling to the membrane itself.

Bone and Bones↗
PubMedDate not supplied

The effect of pulsing electromagnetic field on bone ingrowth into a porous coated implant.

Electromagnetic stimulation is known to promote bone formation in cases of fracture and pseudoarthrosis. The possibility of using electromagnetic field to promote bone ingrowth into a porous coated implant was investigated in this study using Japanese albino rabbits. A titanium implant coated with beads of 250-300 microns in diameter around a stem of 1.7 mm in diameter was inserted into the humerus cavity of a Japanese albino rabbit. The humerus was stimulated by pulsing electromagnetic fields at 2 Gauss, 10Hz, 25 microseconds for 14 days. The circumference of grown bone into the implant was measured, and calculated in area equivalent for determination of the area of new bone. Bone ingrowth was significantly promoted by consecutive 14 days. The result suggests that electromagnetic stimulation is useful for achieving further bone ingrowth into a porous coated implant.

Animals↗
PubMed2006

Controlling electromagnetic fields.

Using the freedom of design that metamaterials provide, we show how electromagnetic fields can be redirected at will and propose a design strategy. The conserved fields-electric displacement field D, magnetic induction field B, and Poynting vector B-are all displaced in a consistent manner. A simple illustration is given of the cloaking of a proscribed volume of space to exclude completely all electromagnetic fields. Our work has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.

Journal Article↗
PubMed1997

Pulsed magnetic and electromagnetic fields in experimental achilles tendonitis in the rat: a prospective randomized study.

OBJECTIVE: To investigate the effects of pulsed magnetic fields (PMF) and pulsed electromagnetic fields (PEMF) on healing in experimental Achilles tendon inflammation in the rat. DESIGN: Prospective randomized trial. SETTING: University medical school. METHODS: Exposure of the Achilles tendon and injury by a weight of 98.24 g falling from a height of 35cm in 180 male Sprague-Dawley rats. INTERVENTION: A daily 15-minute session with PMF of 17Hz or 50Hz, or PEMF of 15Hz or 46Hz, or a sham session. OUTCOME MEASURES: Random sacrifice 2 hours after the operation, and at 1, 3, 7, 14, or 28 days. Assessment of water content, weight, and histological appearance of the tendons. RESULTS: The time from injury and the various treatment modalities exerted a significant influence on the water content of the tendon after the injury (two-way ANOVA, p = .02). At day 3, the water content of the PEMF 46Hz group was significantly higher than in the other groups, decreasing sharply by day 7, and being similar to the other groups thereafter. By the end of the experiment, the PEMF 15Hz group was not significantly different from the control group. At day 7, the PMF 50Hz group showed significantly lower water content than the control group (p = .03), but at 14 days the PMF 50Hz group was not significantly different from the control group. PMF 50Hz suppressed the extravascular edema during early inflammation. PMF 17Hz showed a similar initial trend, producing a consistent lower water content throughout the experiment, reaching statistical significance by the end of treatment. By the end of the experiment, the collagen fibers had nearly regained their normal alignment in all groups, with a more physiological alignment seen in the PEMF 17Hz group. CONCLUSIONS: The tendon returned to histological normality in all groups, but the PMF 17Hz group showed better collagen alignment by the end of the study. PMF 17Hz resulted in a greater reduction of inflammation, with a better return of the tendon to histological normality. Different PMF and PEMF could be applied according to when treatment is started after the injury. If there is no delay between injury and beginning of pulsed magnetic treatment, PMF 17 should be used.

Achilles Tendon↗
PubMed2001

Effect on human attention of exposure to the electromagnetic field emitted by mobile phones.

This study examined the effect of exposure to the electromagnetic field emitted by mobile phones on human attention. Three measures of attention were administered to 72 teenagers, 37 of whom were mobile phone users. The results showed that the mobile phone users performed better on one of the three measures of attention than did the non-mobile phone users. The results suggest that exposure to the electromagnetic field emitted by mobile phones may have a mild facilitating effect on attention functions, which is consistent with previous observations that exposure to the electromagnetic field has a facilitating effect on cognitive processing. The possibility that mobile phone users may be naturally better at multiple tasking tasks was discussed.

Adolescent↗
PubMed1994

Treatment of delayed unions and nonunions of the proximal fifth metatarsal with pulsed electromagnetic fields.

Nine delayed unions and nonunion of the proximal fifth metatarsal were treated with pulsed electromagnetic fields (PEMF). All fractures healed in a mean time of 4 months (range 2-8 months). Those fractures treated with both pulsed electromagnetic fields and a nonweightbearing cast healed in a mean time of 3 months (range 2-4 months). The average duration of follow-up was 39 months (range 24-60 months). There were no refractures. When compared with reported healing times and morbidity for conventional casting, medullary curettage with inlay bone, and closed axial intramedullary screw fixation, pulsed electromagnetic fields provided an effective alternative for the treatment of delayed unions and nonunion of the proximal fifth metatarsal.

Adult↗
PubMed2004

No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice.

BACKGROUND: Several reports indicated that non-thermal electromagnetic radiation such as from mobile phones and base stations may promote cancer. Therefore, it was investigated experimentally, whether 900 MHz electromagnetic field exposure influences lymphoma development in a mouse strain that is genetically predisposed to this disease. The AKR/J mice genome carries the AK-virus, which leads within one year to spontaneous development of thymic lymphoblastic lymphoma. METHODS: 320 unrestrained female mice were sham-exposed or exposed (each n = 160 animals) to GSM like 900 MHz electromagnetic fields for 24 hours per day, 7 days per week, at an average whole body specific absorption rate (SAR) value of 0.4 W/kg. Animals were visually checked daily and were weighed and palpated weekly. Starting with an age of 6 months, blood samples were taken monthly from the tail. Animals with signs of disease or with an age of about 46 weeks were sacrificed and a gross necropsy was performed. RESULTS: Electromagnetic field exposure had a significant effect on body weight gain, with higher values in exposed than in sham-exposed animals. However, survival rate and lymphoma incidence did not differ between exposed and sham-exposed mice. CONCLUSION: These data do not support the hypothesis that exposure to 900 MHz electromagnetic fields is a significant risk factor for developing lymphoma in a genetically predisposed species, even at a relatively high exposure level.

Animals↗
PubMed2000

Teratogenic effects of sinusoidal extremely low frequency electromagnetic fields on morphology of 24 hr chick embryos.

To examine the potential teratogenicity of electromagnetic fields (EMF; sinusoidal and rectangular) on development of chick embryos (white leghorn), 221 freshly fertilized chicken eggs (55-65 g) were exposed during first 24 hr of postlaying incubation (38 degrees +/- 0.5 degree C) to 24 different EMFs, with 50Hz repetition rate and 8.007-10.143 mT flux density. Following exposure, the exposed fertilized chicken eggs (n = 8-10) and sham-exposed fertilized chicken eggs (n = 15) were incubated simultaneously for 8 more days and unexposed control fertilized chicken eggs (n = 20) for 9 days in absence of EMFs. The embryos were removed from egg shells and studied blind. All 24 EMF exposed-groups (inside the coil with exposure) showed an increase in the percentage of developmental anomalies compared to sham-exposed (inside the coil with no exposure) and control groups (outside the coil). Further, egg's weight was evaluated on day 9. This variable did not show significant difference between control and exposed-groups. The investigation also covered the measurement of body weight, length of crown to rump, length of tip of the beak to occipital bone, heart and liver weight. Statistical comparison between sham-exposed and control values did not show significant differences, but comparison between 8.007, 8.453 and 8.713 mT exposed-groups and control groups showed significant differences; in other exposed-groups, the changes were not significant. These results revealed that 50 Hz electromagnetic fields can induce irreversible developmental alterations in 24 hr chick embryos and confirm that its strength could be a determinant factor for the embryonic response to extremely low frequency electromagnetic fields (window effects).

Animals↗
PubMedDate not supplied

Ambulatory ECG monitoring in workers exposed to electromagnetic fields.

The aim of this study was to evaluate the function of the circulatory system in workers occupationally exposed to medium frequency electromagnetic fields. The subjects were 71 workers at four AM broadcast stations [0.738-1.503 MHz] aged 20-68 (mean 46.9 +/- 13.1) years and 22 workers at radio link stations aged 23-67 (mean 48.2 +/- 17.4) years. Workers at AM broadcast stations experienced 2-40 (mean 18.6 +/- 12.1) years' exposure to electromagnetic fields (average daily exposure dose about 115 Vh m-1, maximum exposure levels during shift about 165 V m-1), workers at radio link stations had no history of regular exposure to electromagnetic fields. In all the subjects a general medical examination, resting ECG and 24 h Holter monitoring were performed. The work organization, work period structure, age, lifestyle, nutritional habits and health status in both groups remained fairly similar. The electrocardiographic abnormalities detected in the resting and/ or 24 h ECG were significantly more frequent (p = 0.006) in workers exposed to electromagnetic fields than in non-exposed subjects (75% versus 25%). A clear tendency for a higher number of rhythm disturbances (mostly ExV) was observed in AM broadcast station workers.

Adult↗
PubMed1988

Effects of pulsed electromagnetic fields on Na+ fluxes across stripped rabbit colon epithelium.

The effect of pulsed electromagnetic fields on the electrical potential and two-way flux of Na+ across the epithelium of the rabbit colon in vitro was investigated. In control experiments the transepithelial mucosal-to-serosal and serosal-to-mucosal fluxes (Jm----s and Js----m) were constant over the experimental period. When the epithelium was at right angles to the applied electromagnetic field, the Jm----s flux of Na+ was reduced, whereas Js----m was enhanced. When the epithelium was rotated 180 degrees, Jm----s was enhanced, whereas Js----m was reduced. When the epithelium was mounted parallel to the magnetic field, both Jm----s and Js----m of Na+ were increased, the latter continuing to increase after the field was turned off. When the tissue was rotated 180 degrees, the same enhanced flux was observed, but now the Jm----s flux showed the greatest increase, which again occurred in the period after the field was turned off. The rate of decrease of transepithelial potential difference in all orientations was less than the control. Also, the conductance increased in orientations 2-4 and decreased in orientation 1 after the field had been applied. This suggests that pulsed electromagnetic fields can have a direct effect on the movement of Na+ across tissue and transepithelial potentials. The mechanism may depend on several factors, such as induced changes in certain ion pumps, the membrane potential, and the surface charge of cell wall proteins.

Animals↗