车载巡测在区域射频电磁环境质量监测与表征中的应用分析

对北京中央电视塔周围25 km²区域电磁环境质量分别进行了射频的网格法手工监测和车载巡测自动监测，通过SPSS软件等对两种监测方法获取的数据进行了统计对比分析，发现两组数据在总体水平及数值分布特征上较为接近，因此车载巡测监测可以替代网格法监测。以车载巡测数据为基础，绘制了实测数据的道路电磁地图，利用插值法绘制了区域电磁地图，对区域电磁环境质量进行了直观表征。从回应公众关注和城市电磁规划出发，建议今后可利用车载巡测监测加强时域和频域的监测。     

Effect of 450 MHz Microwave Modulated with 217 Hz on Human EEG in Rest

Summary This study focuses on discrimination of changes, produced by low-level microwave exposure in intensity and time variability of the human EEG at rest. The power spectral density (PSD) method and nonlinear scaling analysis of the length distribution of low variability periods (LDLVP) were selected for analysis of the EEG signal. During the study, 19 healthy volunteers were exposed to a microwave (450 MHz) of 217 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW/cm². The experimental protocol consisted of ten cycles of repetitive microwave exposure. Signals from frontal, temporal, parietal and occipital EEG channels on EEG theta, alpha and beta rhythms were analysed. Exposure to microwave causes average increase of EEG activity. LDLVP analysis discriminated significant effect in time variability for 2 subjects (11%). PSD method detected significant changes in intensity for 4 subjects (21%). The effect of low-level microwave exposure is stronger on EEG beta rhythm in temporal and parietal regions of the human brain.     

Shielding from ELF Magnetic Fields Emanating from Power Plants in Large Facilities

Summary Large facilities frequently have internal power plants. High power transformers and low voltage cables associated with these plants generate low-frequency magnetic fields of large amplitude, which can be above allowed exposure levels. In order to shield against these magnetic fields large shields are used. These plates are finite and their shielding effectiveness is compromised due to their finite dimensions. This paper evaluates the shielding afforded by such a plate, as related to the geometry of the placement of the source and victim and the dimensions and structure of the shield plate.     

发电与高压输变电工程的工频电磁场现状及防护

通过对典型发电与高压输变电工程工频电磁场的现场检测,阐明了发电与高压输变电工程的工频电磁场现状.在此基础上,根据科学界关于极低频电磁场对人体短期和长期效应研究的明确结论,介绍了发电与高压输变电工程的工频电磁场暴露对人体健康的影响.同时,从卫生安全的角度提出了防止和减少工频电磁场影响的综合防护措施,其中包括:慎重选址,合理设计,适当个体防护和必要的警示标识.另外,扼要地介绍了工频电磁场的有关卫生标准和测量方法.     

EMF effects on microcirculatory system

Authors review the importance of studying the effects of electromagnetic fields (EMF) on microcirculatory system, especially in respect of possibility that vasculature may have direct and indirect role in interaction of static magnetic fields (SMF). We outline the physiological importance of microcirculation and relatively new methods of evaluation technique in vivo and explain in details the local and/or whole body exposure effects of SMF with␣range of 0.3–180 mT, power frequency EMF with range of 0.1–30 mT and microwaves at 1.5 GHz with range 0.08–8 W/kg brain average specific absorption rate (SAR) on microcirculatory systems in different tissues in experimental animals.     

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.     

Individual changes in human EEG caused by 450 MHz microwave modulated at 40 and 70 Hz

This study was aimed to investigate the changes in the human electroencephalographic (EEG) signal caused by modulated low-level microwaves. The 450 MHz microwave exposure modulated at 40 Hz and 70 Hz frequencies was applied to a group of 15 volunteers. The field power density at the scalp was 0.16 mW/cm². Ten cycles of the exposure (1 min on and 1 min off) at both modulation frequencies were applied. Analysis of the EEG signal was performed using three different methods: nonlinear method of scaling analysis for length distribution of low variability periods (LDLVP), relative changes in EEG energy (S-parameter) and beta ratio (H-parameter). The analysis revealed significant changes caused by microwave for the whole group (H-parameter method). The exposure caused increase of the EEG beta power (S-parameter method). Statistically significant changes in EEG were detected for four subjects (26.7%) at 40 Hz modulation frequency (LDLVP method).     

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%.     

Practical aspects of occupational EMF exposure assessment

Electromagnetic fields exposure assessment methodology is briefly presented. The basic problems defined for the practical use of electromagnetic fields measurements and numerical calculations carried out for workers exposure assessment in real occupational situations are discussed. The examples of data from real workplace are presented, focusing: spatial distribution of electromagnetic fields affecting worker’s body, complex characteristics of the frequency content, workers activities/moving in the workplace, field impedance, etc. The situation when the use of calculations is required is discussed. The basic requirements for workers exposure assessment protocols are presented. The possible range of the use of internal and external measures of exposure level is also discussed.     

Preliminary studies about effects of ELF and TAMMEF electromagnetic fields on human lymphomonocytes

In our paper we studied the effects of exposure to ELF (extremely low frequency) or musically generated TAMMEF (therapeutic application of musically modulated electromagnetic fields) electromagnetic fields on the tumor necrosis factor alpha (TNF-α) release induced by a lipopolysaccharide (LPS) from cultured human lymphomonocytes of peripheral blood. Lymphomonocytes, isolated from blood donors buffy-coat, were prepared using standard techniques in cell culture flasks, kept in CO₂ incubator, with controlled temperature and humidity for 5 days. Flasks were subjected to an ELF electromagnetic field (100 Hz sinusoidal) or to TAMMEF electromagnetic fields (with intensity, frequency, and wave shape randomly modified in time, so that all possible codes can occur during a single application). The TNF-α release was determined by ELISA test every 24 h for 92 h and the results were evaluated by a non-parametric test. LPS induces a stronger TNF-α release in cultures that were subjected to ELF when compared with cultures subjected to TAMMEF, at each time period of the experimental protocol. These results seem to indicate that TAMMEF is able to induce a complex modulation of LPS-induced TNF-α release, a cytokine with pro inflammatory property whose release during chronic or neoplastic inflammatory diseases has strong negative effects on several organ systems.