磁共振成像的电磁安全与限值标准

磁共振成像(MRI)是一种将外源电磁能量输入人体后产生物理效应并转换为医学图像信息的技术,包括静磁场、射频场、梯度场共3种电磁场。这3种电磁场均对生物体产生效应,并且在足够的强度下会对人体产生健康危险,如梯度场的神经刺激、射频场(RF)的热效应等电磁危险性。近10年来,美国食品药品监督管理局(FDA)发出MRI检查导致带动脉夹患者死亡的警告、MRI对带植入性神经刺激器患者伤害的通告、MRI对带金属背衬经皮给药帖片患者带来灼伤的通告。然而,当电磁场强度被限制在一定范围内时,MRI仍然是安全的。分析这3种电磁场主要的生物效应和健康危险,讨论国内外有关MRI电磁安全的限值标准。     

近年来弱电磁场(波)生物效应机理研究的进展

由于实验结果的不严密和重复性较差,弱电磁场生物效应的研究一直存在着较大的分歧,但该项研究有着重要的意义,它关系着人类的健康和以电磁波为载体的电子信息产业的发展,本文就近几年来在弱电磁场（波）生物效应的机理研究的作一个综述。     

低频电磁场与细胞信号系统

１引言在２０世纪,环境中的低频电磁场的强度已经大大增强。环境中的低频电磁场主要起源于电的传送,电的分配及电的使用。近年来的研究表明低频电磁场的生物效应是明显的。ＬｉｂｏｆｆＡ在１９８４年报道了交变电磁场对ＤＮＡ合成的影响［１］。ＳｍｉｔｈＳ．等在１９...     

磁场生物效应的研究现状与展望

电磁辐射对人类健康可能的影响日益引起人们的关注,电磁场的生物学效应得到全世界的广泛研究.研究的目的不同,采用的实验手段不同,得到的结论也各有侧重.文中着重介绍了磁场在神经系统、离子通道电特性、血液循环和促骨再生等方面的生物效应的研究现状,并指出在磁场对细胞的作用机制上尚不完全明确,成为研究的热点.目的:提出了磁场生物效应研究的必要性和膜片钳应用于磁场生物效应研究的可行性.方法:阅读大量的国内外相关文献,并做相应的总结分析.结果:总结了磁场生物效应的机理和近年来研究现状,并提出了前景展望.结论:磁场生物效应研究虽然很多,但结果并不完全一致.膜片钳技术已成为细胞电生理研究的有利手段,将其应用于磁场对细胞的作用和影响,将可能会提供更全面、更准确的实验数据.     

电磁波辐射的微循环效应

电磁波辐射是指部分电磁能量脱离能量源以电磁波的形式在空间传播Ⅲ。电磁波辐射的主要来源有广播电视发射装置、通信设备、工业以及医疗应用的高频用电设备、高压输电线路、交通运输的电气化等。随着电力工业的迅速发展与工作、生活现代化带来的电气化程度空前提高，使人类空间电磁波辐射强度呈指数级增长，暴露的电磁场对人类的影响，引起人们的普遍关注。电磁波辐射产生的直接原因是电磁场的变化和有限的传播速度。影响电磁波辐射健康效应的主要参数包括频率和强度，频率越高，辐射的能量也就越多，不同频率的电磁波来源和用途不同，其健康效应也不尽相同。研究表明，小剂量的电磁波辐射对患病机体有一定的临床治疗作用，其机制可能与小剂量电磁波辐射可降低血液黏度，以及抗炎、抗氧化、抑制血管平滑肌和内皮细胞增殖有关。     

弱电磁场与生命系统相互作用的动力学基础——生物代谢动态过程中的电磁干扰

近年来弱电磁场引起的非热生物效应又引起了人们的极大关注，关于非热生物效应的争论也很多。本文将生命系统看作一个由许多非平衡子系统构成的一个复杂系统，从电磁场对生物大分子和化学键的影响论述了电磁场对新陈代谢的干扰，提出了这种干扰导致生物能量贮存的释放的变化，从而产生非热效应的概念。文中的许多假设有待深入的理论研究和实验证实。     

电磁技术用于骨科治疗的研究进展

近年来,电磁场生物效应的研究已被我国列为生物物理学方面的重大课题。电磁技术用于骨科治疗的研究横跨电工技术、生物技术和医学领域。早期的医学研究表明低频电磁场能加速骨折愈。     

胞内钙振荡的同步性对电磁场的响应

电磁场通常通过细胞膜将物理信号转化为生物信号,进而产生生物学效应.本文基于肝细胞钙振荡动力学模型,采用数值分析的方法,研究电磁场对细胞钙振荡同步性的影响,数值结果表明:细胞差异性导致钙振荡的不同,胞间耦合影响钙振荡的同步性;电磁场的频率、强度(调制因子)引起钙振荡的频率和幅值发生变化.     

对确定我国电磁场暴露限值依据的探讨

随着现代化程度的不断提高，环境中各种频段的电磁波越来越多，人群受到的电磁场(EMF)暴露强度也越来越高。充分保护在现代环境中生活和工作的人群健康，维护社会的可持续发展，必须在科学评估电磁场的健康危害效应的基础上，制定合理的电磁辐射暴露限值。所周知，从1950年代以来，分     

低强度极低频电磁场生物效应及特点

低强度极低频电磁场生物效应及特点陈国璋，姜槐（浙江医科大学微波研究室杭州３１０００６）高强度电磁场对生物体的热效应和激发的神经细胞兴奋的作用是众所周知的，但近十多年来大量的实验研究和流行病学调查证明低强度极低频电磁场也有生物学作用。这里低强度是指不使...     

生物电磁学的热点问题研究

随着对电磁场（ＥＭＦ）暴露会引起各种健康问题担扰的增加,以及遭受人为的ＥＭＦ暴露的增加,有关低强度ＥＭＦ的生物学效应及其机制的研究成为生物电磁学领域的主要课题。其中极低频（ＥＬＦ）ＥＭＦ和移动电话所产生的射频ＥＭＦ带来的潜在影响正在引起公共和职业卫生...     

Electromagnetic fields and DNA damage

A major concern of the adverse effects of exposure to non-ionizing electromagnetic field (EMF) is cancer induction. Since the majority of cancers are initiated by damage to a cell's genome, studies have been carried out to investigate the effects of electromagnetic fields on DNA and chromosomal structure. Additionally, DNA damage can lead to changes in cellular functions and cell death. Single cell gel electrophoresis, also known as the ‘comet assay’, has been widely used in EMF research to determine DNA damage, reflected as single-strand breaks, double-strand breaks, and crosslinks. Studies have also been carried out to investigate chromosomal conformational changes and micronucleus formation in cells after exposure to EMF. This review describes the comet assay and its utility to qualitatively and quantitatively assess DNA damage, reviews studies that have investigated DNA strand breaks and other changes in DNA structure, and then discusses important lessons learned from our work in this area.     

The effects of prenatal and neonatal exposure to electromagnetic fields on infant rat myocardium

Introduction

Electromagnetic fields (EMF) have adverse effects as a result of widespread use of electromagnetic energy on biological systems. The aim of this study was to investigate the effects of prenatal exposure to EMF on rat myocardium by biochemical and histopathological evaluations.

Material and methods

In this study, 10 pregnant Wistar rats were used. Half of the pregnant rats were exposed to EMF of 3 mT, and the other half to sham conditions during gestation. After parturition, rat pups in the 5 EMF-exposed litters from birth until postnatal day 20 were exposed to EMF of 3 mT for 4 h/day (EMF-exposed group, n = 30). Rat pups in sham litters from birth until postnatal day 20 were exposed to sham conditions (sham group, n= 20).

Results

In the EMF-exposed group, lipid peroxidation levels significantly increased compared to sham. Superoxide dismutase activities decreased significantly in the EMF-exposed group compared to sham. TUNEL staining showed that the number of TUNEL-positive cells increased significantly in EMF-exposed rats compared with sham. Under electron microscopy, there were mitochondrial degeneration, reduction in myofibrils, dilated sarcoplasmic reticulum and perinuclear vacuolization in EMF-exposed rats.

Conclusions

In conclusion, the results show that prenatal exposure to EMF causes oxidative stress, apoptosis and morphological pathology in myocardium of rat pups. The results of our study indicate a probable role of free radicals in the adverse effects of prenatal exposure to EMF. Further studies are needed to demonstrate whether the EMF exposure can induce adverse effects on the myocardium.     

Effects of electromagnetic fields on cells: physiological and therapeutical approaches and molecular mechanisms of interaction. A review

This review concentrates on findings described in the recent literature on the response of cells and tissues to electromagnetic fields (EMF). Models of the causal interaction between different forms of EMF and ions or biomolecules of the cell will be presented together with our own results in cell surface recognition. Naturally occurring electric fields are not only important for cell-surface interactions but are also pivotal for the normal development of the organism and its physiological functions. A further goal of this review is to bridge the gap between recent cell biological studies (which, indeed, show new data of EMF actions) and aspects of EMF-based therapy, e.g., in wounds and bone fractures.     

Reproductive and developmental effects of EMF in vertebrate animal models

This paper reviews the literature data on the effects of electromagnetic fields (EMF), in the reproductive organs as well as in prenatal and postnatal development of vertebrate animals. Review articles which have been published till 2001, regarding the reproductive and developmental effects of the entire range of frequency of electromagnetic fields, were surveyed. Experimental studies which were published from 2001 onwards were summarized. Special focus on the effects of radiofrequencies related to mobile communication in the above mentioned topics has been made. According to the majority of the investigations, no strong effects resulted regarding the exposure to EMF of mobile telephony in the animal reproduction and development. However further research should be done in order to clarify many unknown aspects of the impact of EMF in the living organisms.     

A 50-Hz electromagnetic field impairs sleep

In view of reports of health problems induced by low frequency (50-60 Hz) electromagnetic fields (EMF), we carried out a study in 18 healthy subjects, comparing sleep with and without exposure to a 50 Hz/1 mu Tesla electrical field. We found that the EMF condition was associated with reduced: total sleep time (TST), sleep efficiency, stages 3 + 4 slow wave sleep (SWS), and slow wave activity (SWA). Circulating melatonin, growth hormone, prolactin, testosterone or cortisol were not affected. The results suggest that commonly occurring low frequency electromagnetic fields may interfere with sleep.     

Reactive oxygen species levels and DNA fragmentation on astrocytes in primary culture after acute exposure to low intensity microwave electromagnetic field

The exposure of primary rat neocortical astroglial cell cultures to acute electromagnetic fields (EMF) in the microwave range was studied. Differentiated astroglial cell cultures at 14 days in vitro were exposed for 5, 10, or 20 min to either 900 MHz continuous waves or 900 MHz waves modulated in amplitude at 50 Hz using a sinusoidal waveform and 100% modulation index. The strength of the electric field (rms value) at the sample position was 10 V/m. No change in cellular viability evaluated by MTT test and lactate dehydrogenase release was observed. A significant increase in ROS levels and DNA fragmentation was found only after exposure of the astrocytes to modulated EMF for 20 min. No evident effects were detected when shorter time intervals or continuous waves were used. The irradiation conditions allowed the exclusion of any possible thermal effect. Our data demonstrate, for the first time, that even acute exposure to low intensity EMF induces ROS production and DNA fragmentation in astrocytes in primary cultures, which also represent the principal target of modulated EMF. Our findings also suggest the hypothesis that the effects could be due to hyperstimulation of the glutamate receptors, which play a crucial role in acute and chronic brain damage. Furthermore, the results show the importance of the amplitude modulation in the interaction between EMF and neocortical astrocytes.     

电磁场促进骨髓间充质干细胞成骨分化的研究进展

目的:探讨电磁场促进骨髓间充质干细胞成骨分化作用的研究现状。方法:检索电磁场和间充质干细胞相关论文,比对寻找电磁场促进成骨的相关证据,总结电磁场促进间充质干细胞成骨分化的相关研究。结果:电磁场对细胞的作用是复杂多样的,可影响干细胞的基因表达,也能对细胞缝隙通讯产生作用,实验室证明电磁场在体外培养的干细胞增殖和分化方面扮演了一定的角色,临床研究同样证明活体的骨细胞会受到电磁场的作用。结论:电磁场能促进骨髓间充质干细胞的成骨分化,近年来国内外在这个领域的研究方兴未艾,进一步深入研究非常必要尤其通讯频段电磁场更值得学术界的探讨。     

Health risks of electromagnetic fields. Part I: Evaluation and assessment of electric and magnetic fields

Exposure to electric and magnetic fields (EMF) emanating from the generation, distribution, and utilization of electricity is widespread. The major debate in recent years has focused on the possibility that exposure to EMF may result in adverse health consequences, including the development of cancer. This article provides a review and evaluation of potential health risks associated with residential and occupational exposure to EMF. In addition to reviewing data from laboratory, epidemiology, and clinical studies, we examine exposure data from field measurement surveys and exposure guidelines that have been established for EMF. Currently, the evidence in support of an association between EMF and childhood cancer is limited, although this issue warrants further investigation. Evidence of an association between EMF exposure and adult cancers, derived largely from occupational settings, is inconsistent, precluding clear conclusions. There is little evidence of an association between EMF and noncancer health effects. Epidemiological studies of EMF and population health are limited by exposure measurement error and the lack of a clear dose/response relationship in studies suggesting possible health risks. Further research is needed to clarify the ambiguous findings from present studies and to determine if EMF exposure poses a health risk.