Clinical aspects of static magnetic field effects on circulatory system

Increased knowledge of the magnetic field influence on hemodynamic function may have significant therapeutic potential and possible health effects. For example, magnetic field therapy using moderate intensity static magnetic fields (SMF) in the mT range (in particular, 1–600 mT) could be useful for circulatory diseases, including ischemic pain, inflammation, and hypertension, primarily due to the modulation of blood flow and/or blood pressure through the nervous system. We suggested that the mechanisms of SMF effects on the circulatory system in the mT range could be mediated by suppressing or enhancing the action of biochemical effectors, thereby inducing homeostatic effects biphasically. The potent mechanisms of SMF effects have often been linked to nitric oxide pathway, Ca²⁺-dependent pathway, sympathetic nervous system (e.g., BRS and the action of sympathetic agonists or antagonists), and neurohumoral regulatory system (e.g., production and secretion of angiotensin II and aldosterone). Thus, this review mainly focuses on the experimental studies of SMF effects on the circulatory system in animals and may provide the physiological basis for future clinical investigations of SMF therapy.     

Immune stimulation in fish and chicken through weak low frequency electromagnetic fields

A hypothesis is proposed how Low Frequency Electromagnetic Field (LF EMF) exposure can stimulate an immune response, based on recent insights in immunology. We hypothesize that the Immunent EMF treatment induces mild stress to cells, which then produce cytokines that function as alarms or so called danger signals for the immune system. In this way EMF treatment takes the place of multiplying pathogens, and the damage these cause, in the triggering of an immune response. In a first series of experiments in␣vitro common carp head kidney-derived phagocytes were used to determine ROS production as a measure for immune activation. Exposure to LF EMF signals (200–5,000 Hz) at 5 μT or 1.5 mT led to 42 or 33% increase in immune activity, respectively, compared to negative control values. EMF could also additionally stimulate chemically pre-stimulated samples up to 18% (5 μT) or 22% (1.5 mT). Significance of increase in ROS production in the total series was: p < 0.0001. In a second series of experiments in␣vitro commercial goldfish were used. Groups of fish were housed under equal conditions in at least four control tanks and 8–16 EMF-exposed tanks. Exposure was done with a predominantly vertical field at field strengths (rms) between 0.15 and 50 μT. Without treatment mortality was about 50% after 18 days, while the treatment at 5 μT reduced it to 20% on average. At field strengths 0.15, 0.5, 1.5, 5, 15 and 50 μT an equally strong effect was found. Reducing the field strength to 0.05, 0.06, 0.01 and 0.003 μT showed a gradually decreasing effect, which only at 0.003 μT is no longer statistically significant. Finally, in␣vitro experiments were done with 560 commercial broiler chickens exposed to infection pressure from coccidiosis. EMF exposure at 6.5 μT reduced intestinal lesions by 40% and improved feed conversion by 8%.     

Subcutaneous Arteriolar Vasomotion Changes During and After ELF-EMF Exposure in Mice in Vivo

Summary Biological effects of extremely low-frequency electromagnetic fields (ELF-EMF) on microcirculation were investigated in vivo by monitoring arteriole diameters in conscious mice. Measurements of blood vessel diameter were monitored 33 min non-stop before during and after exposure with ELF-EMF and every 389 ms blood vessel diameter were calculated. Using a dorsal skinfold chamber (DSC), and following caudal vein injection of FITC-dextran 250 kDa, the microvasculature (initial arteriole diameter of 45–80 μm), was examined by intravital microscopy and video images were recorded for a total time of 33 min. Arteriole diameter was continuously measured by on-line analysis using a High-speed Digital Machine Vision System CV-2100, using an edge-gap detection algorithm. Since vessel diameters exhibit rhythmic variation expressed by vasomotion, for estimation of microcirculatory activity we used both raw data for frequency analysis of vasomotion (measured frequencies of vasomotion were in the range 0.008÷0.1 Hz) and evaluate mean blood vessel diameter for each 1 min period of time, and make a comparison between Pre, Exposure/Sham exposure and Post exposure periods, with the aim to evaluate possible changes in mean blood vessel diameter as a result of ELF-EMF action. During EMF exposure and post-exposure periods, arteriole diameters increased significantly compared with the pre-exposure period, and the changes were larger during post-exposure. In contrast to sham exposure, vasodilatation of the microvasculature was significantly greater during exposure and post-exposure to 16 Hz EMF. These findings suggest that ELF-EMF may have potential therapeutic use benefit for treating vascular disorders.     

Influence of the Interaction of a 900 MHz Signal with Gender on EEG Energy: Experimental Study on the Influence of 900 MHz Radiation on EEG

Summary The effects of electromagnetic fields (EMF) emitted by cellular phones on human electroencephalogram (EEG) were studied during an auditory memory task. The experimental method and the experimental setup are introduced as a credible measurement method of EEG. 19 normal subjects (10 women and 9 men) performed the memory task both with and without exposure to a 900 MHz signal, emitted by a dipole antenna placed near the subjects' head. The energy of the EEG signals was calculated at the time domain. A Fourier transform of the EEG signals was done and the EEG energy was also calculated at the frequency domain. As the Parseval's theorem anticipates the energies were identical. The EEG energy was found concentrated at the four basic bands (α (8–13 Hz), β(14–30 Hz), δ (0–4 Hz) and θ(5–7 Hz)). The primary concern of the present study was the gender related influence of EMF on the spectral energy of EEG. The results show evidence of a strong gender—radiation interaction effect on the EEG energy and on the peak amplitudes within each of the four rhythms. Without radiation the spectral power of males is greater than of females, while under exposure the situation is reversed. Under the influence of EMF the spectral power of the males EEG is decreased while that of the females is increased. In conclusion both the baseline EEG and the changes effected to the EEG power spectrum under the influence of EMF seem to be gender dependent.     

Static magnetic field action on some markers of inflammation in animal model system—in vivo

Experimentally induced acute inflammation in rats is a good model system which includes the complexity and dynamics of the processes; moreover there are many defined markers for following and estimating changes in an observed system. In this paper, we discuss an in vivo model of acute inflammation induced by carrageenan. Carrageenan-induced paw edema is a model of non-infectious acute inflammatory reaction to assess the contribution of mediators involved in vascular changes associated with acute inflammation and potential treatments. A complex approach into the investigation of possible effects of static magnetic fields (SMF) action on experimentally induced acute inflammation in rats (by measurements of the levels of specific stress markers) is very important in understanding the possible inflammatory mitigation effects, pain relief, and oxidative stress state of an organism. This approach could help for better understanding of the possible mechanisms of interaction of dynamic processes such as inflammation healing and pain relief with external SMF (25 mT at 10, 20 and 30 min exposure time). Results indicate that SMF with B = 25 mT for 30 min diminished the inflammatory process and decreased the levels of inflammatory markers (fibrinogen) and stress markers (ACTH, Cor) into the blood plasma in rats as when compared with sham exposed animals. The exact mechanism by which SMF contributes to the acceleration of inflammatory healing and decrease of inflammation markers in blood plasma in rats still remains unclear. We assume that two possible mechanisms exist. One is the direct interaction of SMF with free active oxygen forms (free radicals) affected by their membrane processes and related with the physiological functions. Another possible mechanism might be related to dynamic regulation of inflammation healing process.     

Electromagnetic fields in clinical practice of physical and rehabilitation medicine: a health hazard assessment of personnel

The importance of the assessment of the electromagnetic fields /EMF/ background as a health risk factor for the physiotherapy personnel is discussed in this paper. Wide frequency and amplitude ranges as well as large variety of design prescribed in the rehabilitation program form complicated work conditions. In this paper, we attempt to present and classify this specific work environment, i.e., low intensive EMF background with non homogenous frequency and modulation characteristics, stochastic changes running during day, ground or even underground units’ placement and professional specifics, i.e., chronic EMF expositions, personnel’s trunk and hands exposure, dose-measurement absence, lack of program for prevention and prophylaxis for the assessment of the relatively insufficiently elucidated potential of EMF as a harmful factor for medical staff. Our “Study of the biological effects of the EMF among medical staff from PRM wards—potential of risk reduction”/initialized in 1999/and the original survey card structure are presented in general here first. It has been shown the importance to extend the “native” studies among homogenous professional groups, two of them presented there, as well as the study of the biological effects of EMF in their different aspects, especially taking into account the elevated levels of ionizing and non-ionizing radiation in the environment. This includes the special attention on the exposure of medical staff from PRM units and creation of adequate methods for prevention of unnecessary exposure to these physical factors.     

Influence of a 1,800 MHz electromagnetic field on the EEG energy

The present study investigated the influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on brain activity. Ten women and ten men, matched for age and educational level, performed a short memory task (Wechsler test), with simultaneous Electroencephalogram (EEG) recordings at 15 scalp electrodes, both without (baseline) and with exposure to an 1,800 MHz signal. The EEG energy was found concentrated at the four basic EEG bands [α (8–13 Hz), β (14–30 Hz), δ (0–4 Hz), and θ (5–7 Hz)]. The analysis revealed that in the presence of EMF, the energy of the β band was significantly greater for females than for males at the majority of the electrodes. Since beta oscillation is associated with the shift of attention during the perception, these findings may indicate that the particular EMF (1,800 MHz signal) exerts an influence on this brain activity, which appears to be gender-related.     

Investigation of the effects of static magnetic field on apoptosis in bone marrow stem cells of rat

This research was carried out to evaluate the influence of static magnetic field on the rate of apoptosis in bone marrow stem cells (BMSCs) of rats. Extracted cells were suspended in αMEM as a culture media for 48 h. After that, cells were exposed to 15 mT static magnetic field (SMF) for 5 h, incessantly with or without FeCl₂. The rate of apoptosis was then assessed via flow cytometery. The results showed that either treatment with FeCl₂ or exposure to SMF enhanced the rate of apoptotic cells. Moreover, cells that were treated simultaneously with FeCl₂ and SMF have higher rate of apoptosis. An increase in apoptosis by 26.5% was induced by SMF alone and an increase in apoptosis by 28.2% was induced by a combination of FeCl₂ and SMF, compared to their corresponding controls. The results recommended that the effects of SMF on apoptosis may be related to increment of the number of free radicals in the cells.     

Interlaboratory comparisons in EMF survey measurements

This article presents methods and results of interlaboratory comparison in the electromagnetic field (EMF) survey measurements performed by Electromagnetic Environment Protection Laboratory. Based on the results, the author analyzed factors affecting the precision of EMF measurements, in particular—difficult to estimate—the “human factor”. In practice, the human factor has never been taken into account in the EMF measurements accuracy estimations budget, and the author estimate the importance of this factor that may include even up to half of the total uncertainty of measurements. Taking into account all factors depredating the accuracy of measurements, the uncertainty of the survey EMF measurements was estimated at the level of 2–4 dB.     

Signal processing and wavelet analysis of simultaneously registered blood pressure and laser Doppler flow signals during extremely low frequency electromagnetic field exposure in humans in vivo

Regulation of microcirculation and other physiological processes have strong non-linear character and involves complex of different processes, every process with own hierarchy in time and different frequencies. Traditional Fourier analysis does not provide sufficient power and resolution to elucidate characteristic of low vasomotor frequencies. Therefore, we apply a Time–frequency (wavelet) analysis on the signal obtained by Laser Doppler flow meter (LDF) at 25 healthy volunteers, exposed at the same time to low frequency electromagnetic fields, used for physiotherapy. Signal processing include Matlab based algorithms for digital signal processing (DSP) and Matlab Spectral analysis toolbox of simultaneous registered variations in Blood Pressure (BP), Laser Doppler Flow (LDF), and Intravital microscopy (IVM). It provides useful information about regulatory mechanisms and vegetative nervous system regulation of peripheral blood flow. Continuous changes in blood pressure variations and perfusion of extremities were measured prior and after 10, 20, and 30 min ELF-EMF (10, 16, 20, and 30 mT), exposure. After wavelet analysis of the blood flow signals and vasomotion changes signals, several frequency bands were distinguished: 0.0095–0.02 Hz; (α), 0.02–0.06 Hz; (β), 0.06–0.15 Hz; (γ), 0.15–0.4 Hz; (δ), and 0.4–1 Hz; (θ) for LDF data and 0.0095–0.4 Hz; (α), 0.4–0.75 Hz; (β), 0.75–0.9 Hz; (γ), 0.9–1.2 Hz; (δ), and 1.2–2 Hz; (θ) for IVM data. In this study, overlapping of some frequency bands between IVM and LDF data were found. Overlapping of the frequency bands has two ways of interpretation, one related with similarity of the structures and tissues and other related with output of ELF-EMF stimulation. We used also correlation and cross-correlation analysis to compare non-invasive (BP measurements and LDF) data, with invasive intravital microscopy (IVM) data (obtained on animals in vivo), during ELF-EMF stimulation. IVM data were used as a reference value, for certain information of possible mechanisms of biological response at the tissue and blood vessel level after ELF-EMF exposure with frequency in the range from 10 to 50 Hz and magnetic flux density of 20 mT. Comparative analysis of IVM and LDF, frequency bands show that they have statistical significant changes after ELF-EMF stimulation. Five subintervals were confirmed (α-, β-, γ-, δ-, and θ). The findings indicate that local ELF-EMF exposure at the constant temperature of the media increases skin blood flow at the upper extremities which have a contribution to the α-frequency band at IVM.     

Mobile communications and health of population: the risk assessment, social and ethical problems

Today world population lives in a new electromagnetic environment, characterized with (i) around the clock enforcement of chronic exposure of all age and gender groups to a wide range of modulated electromagnetic fields (EMF) from base stations; (ii) daily, repeated from early childhood throughout entire life exposure to EMF RF mobile phone the brain and vestibular receptor apparatus and auditory analyzers, located directly “under the EMF beam” in the inner ear. On the other hand, the world science and epidemiology is missing well-planned and executed research results of prolonged exposure of EMF RF on the brain. International recommendations and domestic guidelines do not include changing conditions of RF EMF on the population: the brain has become a critical organ, and the children entered the risk group. The population continues to actively use the mobile phone. In this situation the problem of assessing the risk of mobile communications has become a social and ethical.     

Electromagnetic field levels in the working environment in radio and TV stations

Electromagnetic field sources used for communication always have been subject of serious interest. There are many publications concerning exposure and risk assessment of the working in such environment. Results of epidemiological study performed in Bulgaria in the 1990's show exceeding of the maximal permissible values especially in radio stations for the personnel in 24 h working shift [Israel et al. (1992). Study of the electromagnetic in its influence on personnel working in radio and TV stations, Report, National Centre of Hygiene, Medical Ecology and Nutrition; Israel and Tomov (2001). Epidemiological study of the effects of radiofrequency radiation on operators in radio, TV and relay stations, Proceeding of the Eastern European Regional Meeting and Workshop “Measurements and Criteria for Standard Harmonization in the field of EMF Exposure” and WHO EMF Standards Harmonization Meeting, Varna, Bulgaria, 28 April—3 May, 2001, pp.145–153]. In the last years the situation is strongly influenced by the development of the technology which leads to changes in equipment in radio and TV stations, using lower power, facilitate the working regime. The paper presents data of exposure assessment of different professional groups in selected radio and TV stations. Assessment is being performed on basis of EMF parameters values and energetic load calculations according to the national legislation. Data are compared with the results of previous investigation to evaluate the new situation in this branch. Exposure levels are much lower than those in the previous study, and lower compared to the exposure limits, as well [Israel et al. (1992). Study of the electromagnetic in its influence on personnel working in radio and TV stations, Report, National Centre of Hygiene, Medical Ecology and Nutrition; Israel and Tomov (2001). Epidemiological study of the effects of radiofrequency radiation on operators in radio, TV and relay stations, Proceeding of the Eastern European Regional Meeting and␣Workshop “Measurements and Criteria for Standard Harmonization in the field of EMF Exposure” and WHO EMF Standards Harmonization Meeting, Varna, Bulgaria, 28 April—3 May, 2001, pp.145–153].     

Criticism of the philosophy for development of standards for non-ionizing radiation

The new recommendations of WHO and EC for legislation in Europe and other countries concerning non-ionizing radiation (NIR) health and safety include exposure limits that are very debatable. ICNIRP Guidelines propose exposure limits for electromagnetic fields in the frequency range up to 300 GHz based on short-term exposures and on thermal effects. The new EC proposal for optical and laser safety legislation includes classification of sources of radiation—both lasers and other optical sources, but not requirements for the methodology of classification. On the other hand, many new requirements have been set by the WHO publication “Model Legislation for EMF Protection” concerning the responsibilities in the field of EMF health and safety. Many specialists in the field of developing exposure limits have positions very far away from the proposed of the ICNIRP Guidelines philosophy. The results are different approaches in developing standards and exposure limits, and differences more than 100 times in maximal permissible levels. We, the Bulgarian Program Committee on NIR, try to organize working groups and discuss different philosophy for developing exposure limits for more than 10 years. This paper exposes our position in this area.     

Radical Scavengers Suppress Low Frequency EMF Enhanced Proliferation in Cultured Cells and Stress Effects in Higher Plants

Summary In previous publications, we reported that sinusoidal varying magnetic fields (SVMF) modify the activity and dynamics of the malignancy marker adenosine deaminase, and enhance the proliferation of chick embryo fibroblasts (CEF). While the SVMF examined by us (50, 60 & 100 Hz / 0.06–0.7 mT) were all below kT, they may have the potential of altering chemical processes in which excited radicals are involved. We tested this hypothesis in two experimental systems: CEF in culture and Spirodela oligorrhiza (Lemnaceae) (a small aquatic plant, commonly known as Duckweed). CEF were exposed to SVMF of 100 Hz/0.7 mT for 24 h. The addition of the exogenous radical scavengers catalase, superoxide dismutase or vitamin E to the cells during exposure significantly suppressed enhancement of cell proliferation caused by the field (by 79, 67 and 82%, respectively, as evaluated by the MTT colorimetric assay). ¹⁵N NMR analysis of Duckweed plants fed by ¹⁵N-labeled ammonium chloride and exposed to SVMF at 60 and 100 Hz/0.7 mT for 24 h, revealed augmented alanine production. Alanine did not accumulate in the absence of SVMF. The addition of vitamin C, a radical scavenger, reduced alanine production by 82%. Exposure to SVMF resulted in specific metabolic stress effects in Duckweed plants and enhanced proliferation of CEF. In both cases, it is suggested that free radicals are involved.     

The similar effects of low-dose ionizing radiation and non-ionizing radiation from background environmental levels of exposure

The meltdown and release of radioactivity (ionizing radiation) from four damaged nuclear reactors at the Fukushima Nuclear Facility in Japan in March 2011 continues to contaminate air and ocean water even 1 year later. Chronic exposure to low-dose ionizing radiation will occur over large populations well into the future. This has caused grave concern among researchers and the public over the very long period of time expected for decommissioning alone (current estimate from official sources is 30–40 years based on TEPCO in Mid-and long-term roadmap towards the decommissioning of Fukushima Daiichi nuclear power units 1–4, 2011) and the presumed adverse effects of chronic, low-dose ionizing radiation on children, adults and the environment. Ultimately, radioactive materials from Fukushima will circulate for many years, making health impacts a predictable concern for many generations (Yasunari et al. in PNAS 108(49):19530–19534, 2011). There is long-standing scientific evidence to suggest that low-dose ionizing radiation (LD-IR) and low-intensity non-ionizing electromagnetic radiation (LI-NIER) in the form of extremely low-frequency electromagnetic fields and radiofrequency radiation (RFR) share similar biological effects. Public health implications are significant for reconstruction efforts to rebuild in post-Fukushima Japan. It is relevant to identify and reduce exposure pathways for chronic, low-dose ionizing radiation in post-Fukushima Japan given current scientific knowledge. Intentional planning, rather than conventional planning, is needed to reduce concomitant chronic low-intensity exposure to non-ionizing radiation. These are reasonably well-established risks to health in the scientific literature, as evidenced by their classification by World Health Organization International Agency for Research on Cancer as Possible Human Carcinogens. Reducing preventable, adverse health exposures in the newly rebuilt environment to both LD-IR and LI-NIER is an achievable goal for Japan. Recovery and reconstruction efforts in Japan to restore the communications and energy infrastructure, in particular, should pursue strategies for reduction and/or prevention of both kinds of exposures. The design life of buildings replaced today is probably 35–50 years into the future. Cumulative health risks may be somewhat mitigated if the double exposure (to both chronic low-dose IR from the Fukushima reactors and LI-NIER [EMF and RFR] in new buildings and infrastructure) can be dealt with effectively in early planning and design in Japan’s reconstruction.     

Age dependency of high-affinity ouabain receptors and their magnetosensitivity

Age dependency of [³H]-ouabain binding, ⁴⁵Ca²⁺ eflux and its magnetosensitivity in rats’ brain cortex and heart muscle tissues were studied. Curves of dose-dependent [³H]-ouabain binding consisted of three components with different affinities (10⁻⁷–10⁻⁴ M (α₁); 10⁻⁹–10⁻⁷ M (α₂); and 10⁻¹¹–10⁻⁹ M (α₃)). These curves were also characterized by different dose-dependent kinetics. [³H]-ouabain binding with α₃ receptors in brain cortex and heart muscle tissues of young and adult animals had a dose-dependent character, while that in old ones had a dose-independent character. A 0.2 T static magnetic field (SMF) exposure had modulation effect on ouabain binding with α₁, α₂ and α₃ receptors in young rats, while in adult ones, only α₃ receptors were magnetosensitive. In old animals, SMF exposure had no significant effect on ouabain binding with α₃ receptors in brain cortex, while in heart muscle, it had inhibitory effect on it. Age-dependent effect of ouabain impact on ⁴⁵Ca²⁺ efflux showed that all concentrations of ouabain lead to inhibitory effect in young animals’ brain cortex and heart muscle (with the exception of 10⁻¹⁰ and 10⁻⁶ M), while in old ones, it had activation effect as compared with data received without ouabain. SMF exposure in young animals had activation effect on ⁴⁵Ca²⁺ efflux from brain cortex and heart muscle in data without ouabain, and in old rats, ⁴⁵Ca²⁺ efflux from brain cortex was magnetic insensitive. In old animals, SMF increased ⁴⁵Ca²⁺ efflux even after extra low concentration of ouabain. It is suggested that α₃ receptors having a crucial role in the regulation of Na⁺/Ca²⁺ exchange serve as age-dependent magnetosensors of excitable cells.     

The comparative study of the effects of 4 Hz Electromagnetic Fields-, Infrasound-treated and hydrogen peroxide containing physiological solutions on Na pump-induced inhibition of heart muscle contractility

The effects of 4 Hz extremely low frequency Electromagnetic Fields (ELF EMF), Infrasound (IS) and hydrogen peroxide (H₂O₂) on Na⁺–K⁺ pump-induced transient inhibition of heart muscle contractility was studied. It was documented that EMF-treated and H₂O₂-containing physiological solution had synergic depressing effect on Na⁺–K⁺ pump-induced inhibition of muscle contractility, while the IS had elevation effect on it. On the basis of the obtained data the H₂O₂ could be suggested as the messenger through which the stimulation effect of EMF on heart muscle is realised, while the relaxing effect of IS on heart contractility is due to the decrease of CO₂ solubility of muscle bathing aqueous medium.     

The EMF-induced changes in aqua medium’s properties depend on background ionizing radiation, illumination and temperature

The effects of extremely low-frequency electromagnetic field (ELF EMF) and ELF-modulated millimeter waves (MMW) on physicochemical properties of physiological solution (PS) at different environmental medium were studied. The existence of frequency “windows” at 4 Hz and 8 Hz frequencies of ELF EMF and ELF-modulated MMW which have different effects on heat fusion period (HFP), hydrogen peroxide (H₂O₂) formation and oxygen (O₂) content of water solution and different dependency on temperature, background radiation (BGR) and illumination was shown. The obtained data allow us to suggest that cell bathing medium serving as a target through which the biological effects of ELF EMF and ELF-modulated MMW on cells are realized is extra sensitive to environmental factors. Therefore, the variability of experimental data on EMF biological effects, obtained in different laboratories can be explained by different environmental conditions of experiments, which very often are not considered adequately.     

Informing the development of decision support tools for risk management: the case of electrical and magnetic fields

This paper describes tools developed through a community consultative process to help decision makers manage electrical and magnetic fields (EMF) health risk. The process involved in‐depth interviews with experts (N=12) and focus group discussions with seven different stakeholder groups. The results reveal commonly held intense public concerns about the long‐term health effects of EMF. These concerns were further reinforced by the lack of public trust in both government and industry with regards to EMF risk management. Overall, the participants wanted tools that can be used to manage EMF information, scientific uncertainty about EMF and the complex environment in which EMF issues are embedded. The findings contributed to a mapping out of response formats to address public concerns related to risk, hazard, trust, accountability and fairness across a range of stakeholder groups. These tools and their roles in the management of complex and variable risks, involving new circumstances (e.g. privatization) and information (e.g. new scientific studies) are presented. The importance of recognizing and working with uncertainty through adaptive management strategies, using qualitative approaches, is also discussed.     

EMF risk for operators mounting,adjusting and maintaining base stations

In the recent years concerns whether exposure to electromagnetic fields (EMF) from base station antennae can cause adverse health effects are grown. Great attention is paid on risk of EMF exposure to people living in a close proximity of base stations. In this issue, a point of interest is the personnel mounting, adjusting and maintaining base stations. Their working tasks require stay in high EMF levels’ conditions. There are only few studies concerning this specific occupational group. The results from our previous investigation (COST 281—Graz, 2006) show that in many cases on performing some specific tasks operators are overexposed according to our national legislation, and ICNIRP guidelines. Here, we present an extended study covering more base stations and more precise scenario for performed tasks and working positions. Results of exposure assessment are presented. They include energetic load calculations on the basis of Bulgarian national legislation, and the corresponding SAR values. Data are used to determine permissible time duration for each particular work operation and served as a base for limiting the exposure and proposal for protective measures for the personnel.