孕期极低频电磁场暴露与出生缺陷关系

极低频电磁场(extremely low frequency electromagnetic fields,ELF-EMFs)是频率在300Hz以下的交变电磁场,主要由电力供应设备和各类家用电器产生.该频段的波长很长,本质上是一种感应场[1].国内外已经进行了大量极低频电磁场与人体健康的研究,发现极低频电磁场对神经系统、免疫系统、生殖系统等均可能产生影响,但是有关孕期ELF-EMFs与出生缺陷的研究还存在争议.本文从流行病学研究及动物实验2方面对孕期极低频电磁场暴露与出生缺陷的关系作一综述.     

极低频电磁场暴露的健康效应

旨在使人们对环境极低电磁场暴露的健康效应有一个正确的认识，从流行病学研究和整体动物研究两个方面，对极低频电磁场暴露的健康危害进行了评价，提示环境极低频电磁场暴露与肿瘤的危险度，以及其他非肿瘤性健康效应之间的相关性是很微弱的，甚至是不确定的。     

极低频脉冲电磁场的生物学效应及机理探讨

为了探讨电磁场引起的生物效应与磁场作用剂量的关系，观察了极低频脉冲电磁场对小白鼠腹腔吞噬细胞吞噬功能的影响。结果表明，电磁场引起的生物效应与磁场强度和磁场作用时间有关，并试从物理量子效应的角度对其机理进行了探讨。     

极低频电磁场与儿童白血病关系的研究进展

极低频电磁场(Extremely Low Frequency Electromagnetic Field,简称ELF-EMF)是指频率在0~300Hz的交变电磁场。其中50~60Hz的极低频电磁场与生产、生活关系最为密切,也是目前国际公认的与儿童白血病相关的频段。     

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.     

极低频电磁场与癌症

随着现代电子工业技术的飞跃发展，电磁能在军事、科研、工农业生产、通讯等行业已广泛应用，现已进入了家庭生活。接触电磁场的人数和空间电磁场强度已逐渐增加，电磁场污染及其对人体健康的潜在危害，已引起各国学者的普遍关注。自1979年hertheimer和Leener的研究提示高压线与儿童白血病之间具有相关性’‘’以来，众多流行病学研究已将重点集中于极低频（EX－tremelyLowFreauency，ELF）电磁场与癌症之间的关系上，然而生物学研究尚未证实两者之间的因果关系“”’。ELF电磁场频率为0～300HZ。高压线、视屏显示终端（VDT）和家用…     

极低频电磁场与儿童白血病的关系Meta－analysis研究

本文应用Ｍｅｔａ－ａｎａｌｙｓｉｓ等方法，对国内外关于极低频电磁场与儿童白血病关系的九个研究资料进行统计合并与综合分析，结果表明，九个研究的结果具有一致性，极低频电磁场是儿童白血病的危险性因素，ＯＲ＝１．６３７２，９５％Ｃ．Ｉ＝１．２９７７～２．０６５６Ｐ＜０．０１。合并人群归因危险度为７．７５％。     

极低频电磁场对人体健康效应的流行病学研究进展

极低频电磁场对人体健康的效应自20世纪70年代以来受到了广泛的关注,在肿瘤,尤其是儿童白血病以及神经行为、神经退行性疾病、心血管疾病、生殖功能、子代发育、免疫学和血液学等方面进行了大量的流行病学研究,本研究对上述研究结果进行综述。     

极低频电磁场对大鼠脑组织抗氧化系统的影响

目的研究极低频电磁场对大鼠脑组织抗氧化系统的影响及其机制。方法选择健康成年Wistar大鼠20只,随机分为2组,即对照组和实验组,每组10只;实验组进行频率为12Hz、强度为0.9mT交变极低频电磁场暴露,每天暴露8h,连续15d,对照组不进行电磁场暴露。结果暴露于极低频电磁场的大鼠血清丙二醛(MDA)含量降低,脑组织中谷胱甘肽(GSH)含量和超氧化物歧化酶(SOD)活力明显增加,与对照组比较,差异有显著性(P<0.05或P<0.01)。结论频率为12Hz、强度为0.9mT的极低频电磁场可能具有增加抗氧化酶活力,使大鼠脑组织抗氧化能力增强的作用。     

极低频电磁场生物效应的第二信使作用机制

随着人类社会的发展，日益增强的环境空间极低频电磁场已成为新的可能致癌源。揭示极低频电磁场生物效应的机制是防护其不良效应的关键。细胞内的第二信使在细胞外界作用因子的信号传递过程中起到承上启下的枢纽作用，因此研究第二信使有利于了解电磁场生物效应的机制。本文就极低频电磁场与细胞第二信使间的相互作用研究进展进行综述。     

Is epidemiology implicating extremely low frequency electric and magnetic fields in childhood leukemia?

We have reviewed epidemiological studies examining the association between residential exposure to extremely low frequency electric and magnetic fields (ELF-EMF) and childhood leukemia. We have excluded studies focusing on electrical appliances, because it is difficult to consolidate transient exposure from multiple sources and equally difficult to control information bias. We have identified 24 studies of residential exposure to ELF-EMF and childhood leukemia. About half of these studies were reported as positive and the remaining as null. For each of the studies reported as positive, however, one or more sources of bias could not be confidently excluded. Moreover, studies which were methodologically more sound, or benefited from high quality registry data, were more frequently null than other investigations. We conclude that the empirical evidence in support of an association between ELF-EMF and childhood leukemia is weak.     

Magnetic field exposure and arrythmic risk: evaluation in railway drivers

Recent studies suggest that professional exposure to Extremely Low Frequency-Electro Magnetic Field (ELF-EMF) can increase the risk of sudden cardiac death. Aim of our work was to find predictive parameters of arrhythmic risk in a population of 28 railways drivers exposed to ELF-EMF.Our findings were that the exposure did not reduce HRV and did not increase the risk of arrhythmias.     

Evaluation of genotoxic and/or co-genotoxic effects in cells exposed in vitro to extremely-low frequency electromagnetic fields

During the last two decades, concerns have arisen regarding a possible association between extremely-low frequency (ELF) electromagnetic fields (EMF) exposure and cancer incidence (e.g. childhood acute leukaemia, cancer of the nervous system, and lymphomas). In 1979, Wertheimer and Leeper firstly reported an excess of cancer mortality among children living in homes located near power lines and presumably exposed to elevated magnetic fields. Subsequently, a large number of epidemiological studies investigated the possible association between residential or occupational exposure to ELF-EMF and cancer. Several in vivo and in vitro models have been investigated with the effort to determine a link, if any, between such fields and mutagenesis and to determine the possible mechanism of cancer risk. However, a causal relationship between exposure to ELF-EMF and cancer has been suggested but has not been unequivocally demonstrated. In 1998, following an analysis of the results retrieved in the literature, the U.S. National Institute of Environmental Health Sciences proposed to apply a "possible human carcinogen" category (Group 2B) to ELF-EMF. More recently, in 2002, the same classification for ELF-MF was proposed by the International Agency for Research on Cancer. In this in vitro approach, to test the genotoxic and/or co-genotoxic potency of ELF-MF, we used the alkaline single-cell microgel-electrophoresis (comet) assay and the cytokinesis block micronucleus test. Co-exposure assays were performed in the presence of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitroquinoline N-oxide (4NQO), benzene, 1,4-benzenediol (1,4-BD), or 1,2,4-benzenetriol (1,2,4-BT). An ELF-MF (50 Hz, 5 mT) was obtained by a system composed of capsulated induction coils. ELF-MF alone was unable to cause direct primary DNA damage. Whereas, an increased extent of DNA damage was observed in cells co-exposed to ELF-MF and MNNG, 1,4-BD, or 1,2,4-BT. An opposite trend was observed in cells treated with 4NQO and co-exposed to ELF-MF. Moreover, the frequency of micronucleated cells in ELF-MF-exposed cells was higher than in control cultures. Our findings suggest that the tested ELF-MF (50 Hz, 5 mT) possess genotoxic (micronucleus test) and co-genotoxic (comet assay) capabilities. The possibility that ELF-MF might interfere with the genotoxic activity of xenobiotics has important implications, since human populations are likely to be exposed to a variety of genotoxic agents concomitantly with exposure to this type of physical agent.     

空气中的甲醛污染与白血病关系的研究进展

白血病是人类最常见的恶性肿瘤之一,严重威胁人群的身心健康。随着环境污染的日益严重,环境暴露与白血病之间的关系引起了人们的普遍关注。该文通过甲醛的特性、室内空气甲醛的来源及其对人体的危害、毒性及致癌作用,国内外关于甲醛与白血病关系的研究等方面进行了综述,以探讨甲醛污染与白血病关系的研究进展。     

Quantification of lifetime accumulated ELF-EMF exposure from household appliances in the context of a retrospective epidemiological case-control study

In Europe household appliances are a major source of indoor 50 Hz magnetic field exposure. A number of epidemiological studies have reported associations between leukemia risk and personal use of household appliances. In the "Norddeutsche Leuk?mie und Lymphomstudie" (NLL), which was conducted in Northern Germany (Schleswig-Holstein and Lower Saxony) between 1997 and 2001, lifetime use of a preselected array of electric appliances (microwave ovens, hair-dryers, motorized electrical alarm clocks (i.e. that use a motor to move their hands or digits), electric blankets and pillows, heated waterbeds, computers with conventional screens, TVs, and electric sewing machines) was recorded in a standardized, personal, computerized interview. Exposure was assessed on three different levels of precision: ever use, cumulative appliance-years, and average time of daily use. Additional questions referred to exposure modifying factors, including distance from screen while watching TV, position of an alarm clock at the bed etc.). Exposure to ELF-EMF from household appliances was quantified as ever vs. never use, gross and net appliance-years of lifetime use and cumulative microT-hours. Flux densities were based on measurements of appliances from the published literature. These were used as weighting factors to account for the different device-specific contributions to overall ELF-EMF exposure. Resulting distributions (as quartiles) for exposure scores revealed systematic differences for different levels of precision. Our analysis indicates that valid assessment of ELF-EMF exposure from household appliances should be based on the highest possible degree of precision and hence provides a considerable challenge in analytic epidemiology.     

Assessment of biological changes of continuous whole body exposure to static magnetic field and extremely low frequency electromagnetic fields in mice

The question whether static magnetic fields (SMFs) and extremely low frequency electromagnetic fields (ELF-EMF) cause biological effects is of special interest. We investigated the effects of continuous whole body exposure to both fields for 30 days on some liver and blood parameters in mice. Two exposure systems were designed; the first produced a gradient SMF while the second generated uniform 50 Hz ELF-EMF. The results showed a gradual body weight loss when mice were exposed to either field. This is coupled with a significant decrease (P<0.05) in the levels of glucose, total protein and the activity of alkaline phosphatase in serum. A significant increase in lactate dehydrogenase activity was demonstrated in serum and liver paralleled with a significant elevation in hepatic γ-glutamyl transferase activity. The glutathione-S-transferase activity and lipid peroxidation level in the liver were significantly increased while a significant decrease in hepatic gluthathione content was recorded. A significant decrease in the counts of monocytes, platelets, peripheral lymphocytes as well as splenic total, T and B lymphocytes levels was observed for SMF and ELF-EMF exposed groups. The granulocytes percentage was significantly increased. The results indicate that there is a relation between the exposure to SMF or ELF-EMF and the oxidative stress through distressing redox balance leading to physiological disturbances.     

Effects of short-term exposure to powerline-frequency electromagnetic field on the electrical activity of the heart

ABSTRACT The heart is a contractile organ that can generate its own rhythm. The contraction, or the rhythm, of the heart may be influenced by electromagnetic field (EMF) exposure, because of the heart's excitability characteristic. In previous studies, different methods have been used to study the possible effects of an extremely low frequency electromagnetic field (ELF-EMF) on the heart. But the studies' designs were not similar, and the results were also different. Recent studies have shown some evidence that short-term EMF exposure can influence the heart more than long-term exposure. This study investigated how the heart is affected in the first EMF exposure. In a simulation of the daily exposure of humans to a power frequency, Wistar albino rats were used. By utilizing the Helmholtz-coil set, we obtained a 50-Hz, 1-μT EMF and examined rat heart activity during short-term EMF exposure. No effect was observed under this exposure condition. The results obtained do not confirm a possible mechanism in the electrical activity of the rat heart model.     

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells

Whether exposure of humans to extremely low frequency electromagnetic fields (ELF-EMF) can cause cancer is controversial and therefore needs further research. We used a Friend erythroleukemia cell line that can be chemically induced to differentiate to determine whether ELF-EMF could alter proliferation and differentiation in these cells in a manner similar to that of a chemical tumor promoter. Exposure of this cell line to 60 Hz ELF-EMF resulted in a dose dependent inhibition of differentiation, with maximal inhibition peaking at 40% and 40 mG (4 microT). ELF-EMF at 10 mG (1.0 microT) and 25 mG (2.5 microT) inhibited differentiation at 0 and 20%, respectively. ELF-EMF at 1.0 (100) and 10.0 G (1,000 microT) stimulated cell proliferation 50% above the sham-treated cells. The activity of telomerase, a marker of undifferentiated cells, decreased 100[times] when the cells were induced to differentiate under sham conditions, but when the cells were exposed to 0.5 G (50 microT) there was only a 10[times] decrease. In summary, ELF-EMF can partially block the differentiation of Friend erythroleukemia cells, and this results in a larger population of cells remaining in the undifferentiated, proliferative state, which is similar to the published results of Friend erythroleukemia cells treated with chemical-tumor promoters.     

空气污染和低出生体重

空气污染与低出生体重之间的关系的研究在国外已有较多报道,通过回顾文献发现,孕期接触空气中的一氧化碳、可吸入颗粒、二氧化硫、二氧化氮、多环有机物、总悬浮颗粒等物质的污染可能与低出生体重的发生有关,但目前发生机制还不明确.