电磁辐射对神经行为和生物电的影响

随着经济的发展和信息时代的来临，各种频段的电磁波充盈整个生活空间，人们暴露于电磁辐射的机会与日俱增，电磁辐射环境污染已经成为继大气污染、水污染、噪声污染之后的新的第四大公害，给职业接触者和居民的健康带来潜在的危害。电磁辐射对人们健康和生活的影响是多方面的，该文就电磁辐射对神经行为、脑电、心电等方面的影响作一综述，以期对电磁辐射的危害作进一步的了解。     

Two-electrode non-differential biopotential amplifier

A circuit is proposed for a non-differential two-electrode biopotential amplifier, with a current source and a transimpedance amplifier as a potential equaliser for its inputs, fully emulating a differential amplifier. The principle of operation is that the current in the input of the transimpedance amplifier is sensed and made to flow with the same value in the other input. The circuit has a simple structure and uses a small number of components. The current source maintains balanced common-mode interference currents, thus ensuring high signal input impedance. In addition, these currents can be tolerated up to more than 10μA per input, at a supply voltage of ±5V. A two-electrode differential amplifier with 2×10 MΩ input resistances to the reference point allows less than 0.5μA per input. The circuit can be useful in cases of biosignal acquisition by portable instruments, using low supply voltages, from subjects in areas of high electromagnetic fields. Examples include biosignal recordings in electric power stations and electrically powered locomotives, where traditionally designed input amplifier stages can be saturated.     

Minimising stimulator artefacts in electromagnetic flow signals

Simultaneous electrical stimulation of tissue with the measurement of blood flow using an electromagnetic flowmeter system almost invariably results in large flow measurement inaccuracies. These inaccuracies are because the electrical energy from stimulating artefacts is amplified along with the flow signals. The paper describes the building and use of an inexpensive circuit to remove stimulation artefacts from electromagnetic flow measurements.     

Magnetophosphenes: a quantitative analysis of thresholds

Low-frequency and transient magnetic fields of moderate flux densities are known to generate visual phenomena, so-called magnetophosphenes. In the present study, time-variable very low frequency (10–50 Hz) electromagnetic fields of moderate flux density (0–40 mT) were used to induce magnetophosphenes. The threshold values for these phosphenes were determined as a function of the frequency of the magnetic field both in normal subjects and colour defective ones. Maximum sensitivity occurred at a frequency of approximately 20–30 Hz, and with broad-spectrum light the threshold flux density was 10–12 mT. The threshola values were found to be dependent upon the intensity and the spectral distribution of the background light. Sensitivity decreased during dark adaptation. In certain respects deutans differed from subjects with normal colour vision. Possible mechanisms for generation of magnetophosphenes are discussed. The present magnetic threshold curves show a close resemblance to corresponding curves obtained by electric stimulation at various frequencies provided the electric thresholds are divided by the a.c. frequency. These problems are under current investigation in our laboratory. This is in full agreement with the assumption that the fluctuating magnetic field affects retinal neurons by inducing currents which polarise synaptic terminals.     

Effect Of Pulsatile Electromagnetic Fields On Blood Viscosity And Coagulation

Ithasbeenprovedthatanumberofdiseasesarerelatedwithabnormalityofbloodviscosityandcoagulationinclinicalresearch.Bloodhyperviscosityandhypercoagulationcauseandaccelearatethedevelopmentofcertaindiseases,deathrateofsomeofwhicharerisingwithyears.Lookingforawaytoreducebloodviscosityandrestrainfasterandstrongercoagulationbecomesasubjectdrawingmoreattention.Theproperseofthisresearchwastofindsuchaway.Intheblood,therearechargrdRBC,WBC,PLT,inorganicions,sothattheremustbesensitiveandcomplicatedresponse…     

Experimental analysis of the human perception threshold of a DC electric field

To study the biological effects of extremely low frequency (ELF) electric fields, a fundamental study is conducted of the human perception threshold of an electric field. The perception threshold is measured with human subjects, and the results are analysed. It is clear that field perception is based on the movement of hair and not on other sensations. Variance in the perception threshold and its causes are investigated. The perception threshold decreases by almost 30% as the relative humidity increases from 50 to 90%. The perception threshold is also dependent on the physical condition (length and density) of the hair and the psychological condition (degree of awareness) of the subject. The dependence on these is much smaller than that on relative humidity. The cause of the gender difference in the threshold is ascribed to the difference in the physical condition of the hair. Through this study, some factors to be taken into account for the safety standard are made clear.     

极低频电磁场与儿童白血病关系的Meta分析

目的 探讨极低频电磁场与儿童白血病的关联程度.方法 采用Meta分析的方法,对国内外公开发表的8篇关于极低频电磁场与儿童白血病的流行病学研究文献进行综合定量再分析.根据资料一致性检验采用固定效应模型计算总OR值.结果 极低频电磁场与儿童白血病之间总OR值为1.58,95%可信区间（95%CI）为1.24～2.03,差异有统计学意义（χ^2=13.11,P＜0.01）.结论 极低频电磁场与儿童白血病具有高度联系,是儿童白血病的危险因素之一.     

电磁辐射对生物体的生物学效应

近年来,在职业场所或在家中,电磁辐射的存在越来越广泛.电磁辐射可对生物体具有致伤效应,目前已成为医学领域的重大研究课题.该文就细胞毒性、基因毒性、外遗传毒性这三条基本途径,对电磁辐射引起生物学效应的可能机制作一概要综述.     

Prise en charge des patients porteurs de stimulateurs cardiaques ou défibrillateurs automatiques implantables traités par irradiation

An increasing number of patients with cardiac implantable electronic devices benefit from radiotherapy, warranting specific collaborative management between both radiation oncologists and cardiologists. Interactions between electromagnetic fields, secondary particles and cardiac implantable electronic devices may result in transient and reversible malfunctions with significant consequences depending on the underlying cardiac pathology and the level of patient's cardiac implantable electronic devices dependency. Numerous international guidelines on patients’ management have been proposed and all agree on a total cumulated dose limit at the battery of 5 Gy and on the need for an initial as well as repeated evaluation over time, up to 6 months after the last radiation. The analysis of the published data revealed relatively rare incidence of significant adverse events. The most recent international guidelines underline the feasibility and safety of radiotherapy for cardiac implantable electronic devices holders, with the need for systematic local protocol in all radiotherapy centers.     

对讲机微波辐射对作业人员心电图的影响

目的探讨对讲机微波辐射对作业人员心电图影响。方法于2004年6—7月,选择某企业165名经常使用对讲机的男保安员(工龄为0.5～3.32a)为暴露组,待其使用对讲机后进行心电图检查,另选择该企业80名不使用对讲机的健康男职工(工龄为0.5～3.58a)作为对照组进行心电图检查。结果暴露组窦性心律不齐和窦性心动过缓的百分率、心电图总异常率均高于对照组(P<0.05,P<0.01),暴露组平均心率低于对照组(P<0.01),暴露组P-R间期及Q-T间期比对照组均有延长(P<0.05)。结论该调查中的对讲机使用者心图的改变可能与暴露于对讲机的微波辐射有关。