Public health impact of extremely low-frequency electromagnetic fields

Ultra-thin freestanding graphene films for efficient thermal insulation and electromagnetic interference shielding

The preparation of freestanding graphene films by convenient and environmentally friendly preparation methods is still the focus of attention in various industrial fields. Here, we first select electrical conductivity, yield and defectivity as evaluation indicators and systematically explore the factors affecting the preparation of high-performance graphene by electrochemical exfoliation, then further post-process it under volume-limited conditions by microwave reduction. Finally, we obtained a self-supporting graphene film with an irregular interlayer structure but excellent performance. It is found that the electrolyte is ammonium sulfate, the concentration is 0.2 M, the voltage is 8 V, and the pH is 11, which were the optimal conditions for preparing low-oxidation graphene. The square resistance of the EG was 1.6 Ω sq^-1, and the yield could be 65%. In addition, electrical conductivity and joule heat were significantly improved after microwave post-processing, especially its electromagnetic shielding performance with a shielding coefficient of 53 dB able to be achieved. At the same time, the thermal conductivity is as low as 0.05 W m^-1 K^-1. The mechanism for the improvement of electromagnetic shielding performance is that (1) microwave reduction effectively enhances the conductivity of the graphene sheet overlapping network; (2) the gas generated by the instantaneous high temperature causes a large number of void structures between the graphene layers, and the irregular interlayer stacking structure makes the reflective surface more disordered, thereby prolonging the reflection path of electromagnetic waves among layers. In summary, this simple and environmentally friendly preparation strategy has good practical application prospects for graphene film products in flexible wearables, intelligent electronic devices, and electromagnetic wave protection.

Lightweight MXene-Based Hybrid Aerogels with Ultrabroadband Terahertz Absorption and Anisotropic Strain Sensitivity

MXene aerogels with a three-dimensional (3D) network structure have attracted increasing attention for lightweight electromagnetic wave absorbers. It is intriguing to expand their absorption band, i.e., to the booming terahertz (THz) region, and explore multifunctionality. Herein, we assemble MXene (Ti₃C₂T_x)-based hybrid aerogels into an aligned lamellar architecture using a bidirectional freezing technique. With air pore size and lamellar layer spacing comparable to THz wavelengths, high porosity of the aerogels allows nearly isotropic absorption of 99% and electromagnetic interference (EMI) shielding effectiveness with a remarkable value of 57.5 dB, in the ultrabroad bandwidth ranging from 0.5 to 3.0 THz. Simultaneous, strain-sensing response reflects the macroscopic anisotropy of the network structure of the aerogels. The improved sensitivity is measured for the out-of-lamellar layer plane under 0-30% strain. The corresponding long-term stability and durability persist over 120 stretching-releasing cycles. Our findings thus not only expand multiple functions of MXene in an anisotropic 3D macroscopic form but also clarify its nearly isotropic absorption in the THz band.

3D printing lamellar Ti3C2T x MXene/graphene hybrid aerogels for enhanced electromagnetic interference shielding performance

Two-dimensional (2D) transition-metal carbides and nitrides (MXenes), especially Ti3C2T x nanosheets, offer high conductivities comparable to metal, and are very promising for fabricating high performance electromagnetic interference (EMI) shielding materials. Due to the weak gelation capability of MXenes, MXene/graphene hybrid aerogels were mostly studied. Among those studied, anisotropic hybrid aerogels showed excellent electrical properties in certain direction due to the intrinsic anisotropic properties of 2D materials. However, the present preparation methods for anisotropic hybrid aerogels lack freedom of geometry, and their electrical performances still have room for improvement. In this study, based on our previous work, the lamellar Ti3C2T x MXene/graphene hybrid aerogels generated by 3D printing with Ti3C2T x MXene/graphene oxide (GO) water-TBA dispersions demonstrated enhanced conductivity and electromagnetic interference (EMI) shielding performance. The addition of MXene deeply influenced the lamellar structure of the hybrid aerogels, and made the structure more ordered than that in the 3D printed lamellar graphene aerogels. The printed lamellar MXene/graphene hybrid aerogels achieved a maximum electrical conductivity of 1236 S m-1. The highest EMI shielding efficiency (EMI SE) of the hybrid aerogels was up to 86.9 dB, while the absolute shielding effectiveness (SSE/t) was up to 25 078.1 dB cm2 g-1 at 12.4 GHz. These values are higher than those of most reported anisotropic MXene-based nanocomposite aerogels.

Pulsed High-Peak Power Microwaves at 9.4 GHz Do Not Affect Basic Endpoints in Caenorhabditis elegans

Because of the extensive application of electromagnetic technology, its health impact on humans has attracted widespread attention. Due to the lack of a model organism with a stable response to electromagnetic waves, the research conclusions on the biological effects of electromagnetic waves have been vague. Therefore, the aim of this study was to investigate the effects of irradiation by pulsed 9.4 GHz high-power microwaves with a peak power density of 2126 W/cm² using Caenorhabditis elegans. The development, movement, egg production, ROS, and lifespan of C. elegans were detected at different times after irradiation with different repetitive frequencies of 10, 20, and 50 Hz for 30 min. The results indicated that no obvious changes in basic life indices were induced compared with the sham radiation group, but the survival rate of positive control was significantly decreased compared with other groups, which is of interest for microwave protection research based on C. elegans and provides data for updating safety standards with respect to pulsed high-peak power microwave. © 2021 Bioelectromagnetics Society.

Extremely Low-Frequency Magnetic Fields and the Risk of Childhood B-Lineage Acute Lymphoblastic Leukemia in a City With High Incidence of Leukemia and Elevated Exposure to ELF Magnetic Fields

It is important to study the relationship between extremely low-frequency magnetic fields (ELF-MFs) and childhood leukemia, particularly in locations with a high incidence of this neoplasm in children and an elevated exposure to ELF-MF, such as Mexico City. The aim was to investigate the association between ELF-MF exposure and the risk of B-lineage acute lymphoblastic leukemia (B-ALL). A case-control study was conducted in Mexico City during the period from 2010 to 2011. Residential 24-h ELF-MF measurements were obtained for 290 incident B-ALL patients and 407 controls, aged less than 16 years. Controls were frequency-matched by sex, age (±18 months), and health institution. The adjusted odds ratios (aOR) and 95% confidence intervals (CIs) were calculated. ELF-MF exposure at <0.2 μT was used to define the reference group. ELF-MF exposure at ≥0.3 μT was observed in 11.3% of the controls. Different ELF-MF intensity cutoff values were used to define the highest exposure category; the highest exposure category for each cutoff value was associated with an increased risk of B-ALL compared with the corresponding lower exposure categories. The aORs were as follows: ≥0.2 μT = 1.26 (95% CI: 0.84-1.89); ≥0.3 μT = 1.53 (95% CI: 0.95-2.48); ≥0.4 μT = 1.87 (95% CI: 1.04-3.35); ≥0.5 μT = 1.80 (95% CI 0.95-3.44); ≥0.6 μT = 2.32 (95% CI: 1.10-4.93). ELF-MF exposure as a continuous variable (per 0.2 μT intervals) was associated with B-ALL risk (aOR = 1.06; 95% CI: 1.01-1.12). In the present study, the proportion of children exposed to ≥0.3 μT is among the highest reported worldwide. Additionally, an ELF-MF exposure ≥0.4 μT may be associated with the risk of B-ALL. Bioelectromagnetics. © 2020 Bioelectromagnetics Society.

Embedded flexible and transparent double-layer nickel-mesh for high shielding efficiency

An efficient approach to obtain high shielding effectiveness (SE) in transparent shielding in an optical window field is proposed and demonstrated by fabricating an embedded double-layer metallic mesh (DLMM) comprised of randomly structured Ni meshes on both sides of a flexible substrate, employing a facile and low-cost double-sided nanoimprinting method. The unique nonperiodic random structure contributes to uniform diffraction and eliminates the Moiré fringe generated by double-layer periodic meshes, ensuring high imaging quality for optical applications. The designed DLMM films simultaneously achieve strong shielding in the X-band and high transmittance in the visible spectrum, demonstrating a high transmittance of 88.7% at the 550-nm wavelength and a SE of 46.9 dB at a frequency of 8.2 GHz. An ultra-high SE of 80 dB is achieved at 64.2% transmittance, which reveals the highest reported SE over a metallic mesh for transparent shielding, indicating the high potential for this transparent electromagnetic interference shielding material for practical optical applications.

Extremely Low-Frequency Magnetic Fields Exposure Measurement during Lessons in Elementary Schools

Schools are an important place for children's exposure to electromagnetic fields, which may cause adverse health effects. To better understand environmental extremely low-frequency magnetic fields (ELF-MFs) exposure among elementary school students, we measured numeric values of ELF-MFs in five classrooms at four schools during digital learning class hours. The measurement of ELF-MFs was taken with an EMDEX II field analyzer. Specifically, we examined the level of exposure to ELF-MFs for each student's seating position in the classroom. The results showed that ELF-MFs exposure levels were lower than those in the International Commission on Non-Ionizing Radiation Protection guidelines; however, there were significant differences in the level of magnetic field exposure at each school and at each student's seat. The exposure to ELF-MFs at students' seat positions was mostly caused by electrical appliances, electronic wiring, and distribution boxes, but the exposure level decreased as the distance increased. Therefore, it is important to design safe and appropriate environments for digital learning in schools, such as proper seating arrangements, to avoid ELF-MFs exposure to students as much as possible. Future studies should measure ELF-MFs levels in other areas and investigate the effects of exposure to ELF-MFs during school hours on children's health.

Structuring Hierarchically Porous Architecture in Biomass-Derived Carbon Aerogels for Simultaneously Achieving High Electromagnetic Interference Shielding Effectiveness and High Absorption Coefficient

Developing high-performance electromagnetic interference (EMI) shielding materials with high absorption coefficient is highly desired for eliminating the secondary pollution of reflected electromagnetic wave (EMW). Nevertheless, it has long been a daunting challenge to achieve high shielding effectiveness (SE) and ultralow or no reflection SE simultaneously. Herein, highly porous and conductive carbon nanotube (CNT)-based carbon aerogel with a meticulously designed hierarchically porous structure from micro and sub-micro to nano levels is developed by specific two-stage pyrolysis and potassium hydroxide activation processes. The resultant activated cellulose-derived carbon aerogels (a-CCAs) exhibit an ultrahigh EMI SE of 96.4 dB in the frequency range of 8.2-12.4 GHz in conjunction with an exceptionally high absorption coefficient of 0.79 at a low density of 30.5 mg cm^-3. The successful construction of hierarchically porous structure is responsible for the excellent "structurally absorbing" ability of a-CCAs, and the introduction of CNT-based heterogeneous conductive network can effectively dissipate the incident EMWs by interfacial polarization and microcurrent losses. Moreover, the as-prepared a-CCAs have a water contact angle of as high as 158.3°and a sliding angle of as low as 5.3°, revealing their superhydrophobic feature. The ingenious structure design proposed here provides a possible pathway to overcome the conflict between high EMI shielding performance and ultralow or no secondary reflection, and the as-prepared a-CCAs are exceedingly promising in the application of telecommunication, microelectronics, and spacecraft.

Extremely low frequency electromagnetic fields and cancer: How source of funding affects results

While there has been evidence indicating that excessive exposure to magnetic fields from 50 to 60 Hz electricity increases risk of cancer, many argue that the evidence is inconsistent and inconclusive. This is particularly the case regarding magnetic field exposure and childhood leukemia. A major goal of this study is to examine how source of funding influences the reported results and conclusions. Several meta-analyses dating from about 2000 all report significant associations between exposure and risk of leukemia. By examining subsequent reports on childhood leukemia it is clear that almost all government or independent studies find either a statistically significant association between magnetic field exposure and childhood leukemia, or an elevated risk of at least OR = 1.5, while almost all industry supported studies fail to find any significant or even suggestive association. A secondary goal of this report is to examine the level of evidence for exposure and elevated risk of various adult cancers. Based on pooled or meta-analyses as well as subsequent peer-reviewed studies there is strong evidence that excessive exposure to magnetic fields increases risk of adult leukemia, male and female breast cancer and brain cancer. There is less convincing but suggestive evidence for elevations in several other cancer types. There is less clear evidence for bias based on source of funding in the adult cancer studies. There is also some evidence that both paternal and maternal prenatal exposure to magnetic fields results in an increased risk of leukemia and brain cancer in offspring. When one allows for bias reflected in source of funding, the evidence that magnetic fields increase risk of cancer is neither inconsistent nor inconclusive. Furthermore adults are also at risk, not just children, and there is strong evidence for cancers in addition to leukemia, particularly brain and breast cancer.

PS/PANI/MoS2 Hybrid Polymer Composites with High Dielectric Behavior and Electrical Conductivity for EMI Shielding Effectiveness

Liquid exfoliated molybdenum disulfide (MoS2) nanosheets and polyaniline (PANI) nanoparticles are dispersed in polystyrene (PS) matrix to fabricate hybrid polymer composites with high dielectric and electromagnetic interference (EMI) shielding behavior. A phase-separated morphology is formed when PANI and MoS2 are incorporated into polystyrene (PS) matrix. An increasing concentration of MoS2 nanoparticles inside PS/PANI (5 wt %) polymer blend forms an interconnected network, resulting in high electrical conductivity and dielectric behavior, making them a suitable candidate for EMI shielding application. An increment in dielectric constant and loss, up to four and five orders of magnitude, respectively, is recorded at a maximum concentration of 1 wt % of MoS2 in PS/PANI-5 polymer blend at 100 Hz. The enhanced dielectric characteristics for PS/PANI/MoS2 composites are then theoretically evaluated for the estimation of EMI shielding effectiveness in the frequency range of 100 Hz to 5 MHz. The maximum dielectric constant and loss achieved for PS/PANI-5 wt %/MoS2-1 wt % are responsible for estimated shielding effectiveness of around 92 dB at 100 Hz. The increase in dielectric behavior and shielding effectiveness is probably due to the increased number of charged dipoles accumulated at the insulator-conductor interface.

Lipidomic alteration and stress-defense mechanism of soil nematode Caenorhabditis elegans in response to extremely low-frequency electromagnetic field exposure

To assess the impacts of man-made extremely low-frequency electromagnetic field (ELF-EMF) on soil ecosystems, the soil nematode was applied as a biological indicator to characterize ecotoxicity of ELF-EMF. In this paper, a soil-living model organism, Caenorhabditis elegans (C. elegans) was exposed to 50 Hz, 3 mT ELF-EMF. The integrated lipidome, proteome and transcriptome analysis were applied to elucidate physiological acclimations. Lipidomic analysis showed that ELF-EMF exposure induced significant alterations of 64 lipids, including significant elevation of triacylglycerols (TGs). Proteome results implied 157 changed protein expressions under ELF-EMF exposure. By transcriptomic analysis, 456 differently expressed genes were identified. Gene Ontology (GO) function and pathway analyses showed lipidomic alteration, mitochondrial dysfunction and the stress defense responses following ELF-EMF exposure in C. elegans. Conjoint analysis of proteome and transcriptome data showed that a higher expression of genes (sip-1, mtl-1 and rpl-11.1, etc.) were involved in stress defense responses to ELF-EMF exposure. These results indicated that ELF-EMF can induce effects on soil nematodes, mainly through disturbing lipid metabolism such as increasing TGs content, and eliciting stress defense responses. This study provided a new understanding in ELF-EMF exposure effects on soil nematodes and suggested a potential way of interpreting ELF-EMF influences on soil ecosystems.

Highly Transparent and Broadband Electromagnetic Interference Shielding Based on Ultrathin Doped Ag and Conducting Oxides Hybrid Film Structures

Reducing electromagnetic interference (EMI) across a broad radio frequency band is crucial to eliminate adverse effects of increasingly complex electromagnetic environment. Current shielding materials or methods suffer from trade-offs between optical transmittance and EMI shielding capability. Moreover, poor mechanical flexibility and fabrication complexity significantly limit their further applications in flexible electronics. In this work, an ultrathin (8 nm) and continuous doped silver (Ag) film was obtained by introducing a small amount of copper during the sputtering deposition of Ag and investigated as transparent EMI shielding components. The electromagnetic Ag shielding (EMAGS) film was realized in the form of conductive dielectric-metal-dielectric design to relieve the electro-optical trade-offs, which transmits 96.5% visible light relative to the substrate and shows an excellent average EMI shielding effectiveness (SE) of ∼26 dB, over a broad bandwidth of 32 GHz, covering the entire X, Ku, Ka, and K bands. EMI SE >30 dB was obtained by simply stacking two layers of EMAGS films together and can be further improved up to 50 dB by separating two layers with a quarter-wavelength space. The flexible EMAGS film shows a stable EMI shielding performance under repeated mechanical bending. In addition, large-area EMAGS films were demonstrated by a roll-to-roll sputtering system, proving the feasibility for mass production. The high-performance EMAGS film holds great potential for various applications in wearable electronics, healthcare devices, and electronic safety areas.

Facile approach for a robust graphene/silver nanowires aerogel with high-performance electromagnetic interference shielding

Robust graphene/silver nanowires (AgNWs) hybrid aerogels were fabricated by facile processes including mixing directly, reducing, and ambient pressure drying. The mechanical properties and electromagnetic interference (EMI)-shielding performance of the resultant hybrid aerogels were investigated in detail. Because silver nanowires with a high aspect ratio have been acting as crosslinkers to bridge two-dimensional graphene sheets, a highly porous and electrically conducting framework can resist high external loading to prevent major deformation and act as an express way for electron transport. Consequently, the hybrid aerogel exhibits large mechanical strength of 42 kPa, 35 times larger than that of the neat reduced graphene oxide aerogel (1.2 kPa), which can resist great damage. More importantly, the as-prepared aerogel possesses high EMI-shielding performance of up to ∼45.2 dB due to its unique nanostructure and good electrical properties. These results indicate that graphene/AgNWs hybrid aerogel prepared using this simplified method promises to be an ideal functional component for mechanically robust and high-performance EMI-shielding nanocomposites.

We report a facile, eco-friendly approach to prepare the robust graphene/silver nanowires aerogel with high compressive strength and excellent EMI shielding performance due to its unique nanostructure and good electrical properties.

The Impact of the Low Frequency of the Electromagnetic Field on Human

Recently, there has been attention and controversial debate topic about the effect of low-frequency electromagnetic fields (EMFs) on human beings. The catalyst for public awareness initiated from the first epidemiological study in 1979 that reported an association between residential EMFs exposure and the incidence of childhood leukemia. For over 40 years, many epidemiological and laboratory investigations were conducted to identify the possible biological effects of low-frequency EMF. Several studies conducted at frequencies 50/60 Hz, which related to generating of electricity from electrical appliances. Experimental studies on low-frequency EMF have provided conflicting data under specific "in vivo" and "in vitro" environments. Some original papers have reported the damaging effect on DNA molecule in EMF-exposed cells. Other studies have suggested no such damage in EMF-exposed cells. Also, the conclusions from other studies were inconclusive. These conflicting findings may attribute to the differences in the apparatus used to generate electromagnetic fields, experimental design, exposure time, genetic endpoints, and biological materials such as cell lines and animal species, strain, and age. As DNA damage is frequently a prerequisite for cancer disease, this review provided an experimental body of evidence on the effect of EMF on genetic material.

Eotaxin‑1 and MCP‑1 serve as circulating indicators in response to power frequency electromagnetic field exposure in mice

The increasing public concern regarding the potential health risks of exposure to electromagnetic fields (EMFs) has led to intensive research in this area. However, it remains unclear whether potential pro-oncogenic effects may be caused by power frequency EMF (PFEMF) exposure. To address the associated risk factors, the present study exposed 4-week old Balb/c mice to 0, 0.1, 0.5 and 2.5 mT of constant 50 Hz Helmholtz coil-type PFEMF for 90 days to explore the circulating chemokine indicators that may be associated with inflammation or cancer. No measurable weight difference existed between the control and PFEMF-exposure groups; however, the Luminex assay clearly demonstrated differentially responsive profiles of circulating chemokines upon PFEMF treatment. Monocyte chemoattractant protein (MCP)-3, macrophage inflammatory protein (MIP)-1α, MIP-1β and MIP-2 levels in serum were not significantly altered by PFEMF during the 3-month exposure period; however, the circulating levels of other chemokines including IP-10, GROα, RANTES, EOTAXIN-1 and MCP-1 exhibited significant changes upon treatment. Among the responsive chemokines, EOTAXIN-1 and MCP-1 were significantly increased by 0.5 mT of PFEMF treatment, which may support their use as indicators of PFEMF exposure. This novel finding highlights the potential pro-inflammatory nature of power frequency, which may shed light on the mechanisms underlying PFEMF-induced diseases, including cancer.

Exosomal small RNA sequencing uncovers the microRNA dose markers for power frequency electromagnetic field exposure

PURPOSE

The potential health risks caused by power frequency electromagnetic field (PFEMF) have led to increase public health concerns. However, the diagnosis and prognosis remain challenging in determination of exact dose of PFEMF exposure.

MATERIALS AND METHODS

Mice were exposed to different magnetic doses of PFEMF for the following isolation of serum exosomes, microRNAs (miRNAs) extraction and small RNA sequencing. After small RNA sequencing, bioinformatic analysis, quantitative real-time PCR (qRT-PCR) validation and serum exosomal miRNA biomarkers were determined.

RESULTS

Significantly changed serum exosomal miRNA as biomarkers of 0.1, 0.5, 2.5 mT and common PFEMF exposure were confirmed. Gene ontology (GO) and Kyoto encyclopaedia of genes and genomes (KEGG) pathway analysis of the downstream target genes of the above-identified exosomal miRNA markers indicated that, exosomal miRNA markers were predicted to be involved in critical pathophysiological processes of neural system and cancer- or other disease-related signalling pathways.

CONCLUSIONS

Aberrantly-expressed serum exosomal miRNAs, including miR-128-3p for 0.1 mT, miR-133a-3p for 0.5 mT, miR-142a-5p for 2.5 mT, miR-218-5p and miR-199a-3p for common PFEMF exposure, suggested a series of informative markers for not only identifying the exact dose of PFEMF exposure, also consolidating the base for future clinical intervention.

Highly Stretchable and Transparent Electromagnetic Interference Shielding Film Based on Silver Nanowire Percolation Network for Wearable Electronics Applications

Future electronics are expected to develop into wearable forms, and an adequate stretchability is required for the forthcoming wearable electronics considering various motions occurring in human body. Along with stretchability, transparency can increase both the functionality and esthetic features in future wearable electronics. In this study, we demonstrate, for the first time, a highly stretchable and transparent electromagnetic interference shielding layer for wearable electronic applications with silver nanowire percolation network on elastic poly(dimethylsiloxane) substrate. The proposed stretchable and transparent electromagnetic interference shielding layer shows a high electromagnetic wave shielding effectiveness even under a high tensile strain condition. It is expected for the silver nanowire percolation network-based electromagnetic interference shielding layer to be beyond the conventional electromagnetic interference shielding materials and to broaden its application range to various fields that require optical transparency or nonplanar surface environment, such as biological system, human skin, and wearable electronics.

24-h personal monitoring of exposure to Power Frequency Magnetic Fields in adolescents - Results of a National Survey

OBJECTIVES

The aim of this exposure assessment study was to gain information about the exposure levels of adolescents in Israel to power frequency (50Hz) magnetic fields (MF) through personal monitoring, and to provide reliable data for national policy development.

METHODS

84 adolescents, 6-10th grade students, carried an EMDEX II meter attached to their body for 24h. The meter recorded the MF every 1.5s. The students documented their activities and microenvironments, such as apartment (awake or asleep), school, transportation, open public areas and other indoor environments.

RESULTS

The geometric mean (GM) of the daily time weighted average (TWA) of all the participants was 0.059 μT (STD = 1.83). This result is similar to those of personal exposure surveys conducted in the UK (GM 0.042-0.054μT), but lower than levels found in the US (GM 0.089 - 0.134μT). The arithmetic mean was 0.073μT, 23% higher than the GM. Fields were lowest at school (GM 0.033μT), and average outdoor exposures were higher than indoor ones. 3.6% of the participants were exposed to daily TWA above 0.2μT. The typical time spent above 0.2μT ranged from few minutes to few hours. The time spent above 0.4μT and 1μT were much shorter, around 1-15min and from few seconds to 2min, respectively. Momentary peaks ever recorded were in the range of 0.35-23.6μT CONCLUSIONS: Exposure of adolescents in Israel is similar to data reported in other countries, being below 0.1μT for the vast majority, with very few average exposures above 0.2μT. Analysis of the different microenvironments allows for a cost-effective and equitable policy development.

Ion-Electron-Conducting Polymer Composites: Promising Electromagnetic Interference Shielding Material

Polymer nanocomposites consisting of poly(vinylidenefluoride-co-hexafluoropropylene) PVdF-HFP, inorganic salt (LiBF4), organic salt (EMIMBF4), multiwalled carbon nanotubes (MWCNTs), and Fe3O4 nanoparticles were prepared as electromagnetic shield material. Improvement in conductivity and dielectric property due to the introduction of EMIMBF4, LiBF4, and MWCNTs was confirmed by complex impedance spectroscopy. The highest conductivity obtained is ∼1.86 mS/cm. This is attributed to the high ionic conductivity of the ionic liquids and the formation of a connecting network by the MWCNTs facilitating electron conduction. The total electromagnetic interference (EMI) shielding effectiveness has a major contribution to it due to absorption. Although the total shielding effectiveness in the Ku band (12.4-18 GHz) of pure ion-conducting system was found to be ∼19 dB and that for the polymer composites which are mixed (ion + electron) conductors is ∼46 dB, the contributions due to absorption are ∼16 and ∼42 dB, respectively.

Influence of Electromagnetic Fields on Lead Toxicity: A Study of Conformational Changes in Human Blood Proteins

Background

Electromagnetic fields (EMF) are associated with oxidative stress, which is in turn associated with reactive oxygen species (ROS), anemia, and hypoxia.

Objectives

This study focused on the synergistic effects of lead ions and EMF on oxidative modifications in hemoglobin (Hb) and plasma proteins.

Patients and Methods

In this experimental study, the blood samples were obtained from age- and sex-matched healthy subjects at Arak University of Medical Sciences, Arak, Iran. The collected bloods were prepared as 55 samples and then divided into different groups for incubating with 0 to 100 uM of lead ions in 2 mT and 50 Hz of EMF for 120 minutes. The carbonyl group was determined to be an oxidative biomarker in plasma proteins. The ferric reducing ability of plasma (FRAP) was considered to be an antioxidant power of human plasma. The conformational changes in hemoglobin, met-Hb, and hemichrome were considered to be oxidative markers in red blood cells. To predict the factors affecting the oxyHb, the artificial neural network (MLP: 11,2,2,1) in SPSS software was applied.

Results

The test subjects showed increased concentrations of metHb (1.8 ± 0.19 vs. 1.36 ± 0.25) and hemichrome (6.01 ± 0.57) in relation to the control subjects. The decreased absorbance at 340 nm (0.88 ± 0.09 vs. 1.07 ± 0.08) demonstrated the reduced interaction between the globin chain and the heme ring. The decreased absorbance at 420 nm (Soret band) (2.96 ± 0.13) and the increased absorbance at 630 nm (0.07 ± 0.002 vs. 0.064 ± 0.005) indicated the conversion of oxyHb to metHb, which confirmed the oxidative damage to the erythrocytes. The linear regression analysis showed significant positive correlations between lead concentration and the percentage of plasma carbonyl content (R2 = 0.96), the relation of plasma carbonyl content to Hb absorbance at 630 nm (R2 = 0.97), and the relation of plasma carbonyl content to metHb concentration (R2 = 0.95) after 120 minutes incubation with lead ions in 20 millitesla and 50 hertz EMF. The artificial neural network analysis showed the significant importance of hemichrome, PCO, metHb, and lead concentration to the oxyHb content of erythrocytes.

Conclusions

Lead contamination in the presence of an EMF exacerbates the oxidative damage to plasma proteins as well as the conformational changes in Hb. An artificial neural network can be used as a predictive tool for the oxidative danger posed to workers in industrial fields, battery manufacturing companies, and power plants.

Exposure to extremely low frequency electromagnetic fields alters the calcium dynamics of cultured entorhinal cortex neurons

Previous studies have revealed that extremely low frequency electromagnetic field (ELF-EMF) exposure affects neuronal dendritic spine density and NMDAR and AMPAR subunit expressions in the entorhinal cortex (EC). Although calcium signaling has a critical role in control of EC neuronal functions, however, it is still unclear whether the ELF-EMF exposure affects the EC neuronal calcium homeostasis. In the present study, using whole-cell recording and calcium imaging, we record the whole-cell inward currents that contain the voltage-gated calcium currents and show that ELF-EMF (50Hz, 1mT or 3mT, lasting 24h) exposure does not influence these currents. Next, we specifically isolate the high-voltage activated (HVA) and low-voltage activated (LVA) calcium channels-induced currents. Similarly, the activation and inactivation characteristics of these membrane calcium channels are also not influenced by ELF-EMF. Importantly, ELF-EMF exposure reduces the maximum amplitude of the high-K(+)-evoked calcium elevation in EC neurons, which is abolished by thapsigargin, a Ca(2+) ATPase inhibitor, to empty the intracellular calcium stores of EC neurons. Together, these findings indicate that ELF-EMF exposure specifically influences the intracellular calcium dynamics of cultural EC neurons via a calcium channel-independent mechanism.

Potential health impacts of residential exposures to extremely low frequency magnetic fields in Europe

Over the last two decades residential exposure to extremely low frequency magnetic fields (ELF MF) has been associated with childhood leukaemia relatively consistently in epidemiological studies, though causality is still under investigation. We aimed to estimate the cases of childhood leukaemia that might be attributable to exposure to ELF MF in the European Union (EU27), if the associations seen in epidemiological studies were causal. We estimated distributions of ELF MF exposure using studies identified in the existing literature. Individual distributions of exposure were integrated using a probabilistic mixture distribution approach. Exposure-response functions were estimated from the most recently published pooled analysis of epidemiological data. Probabilistic simulation was used to estimate population attributable fractions (AFP) and attributable cases of childhood leukaemia in the EU27. By assigning the literature review-based exposure distribution to all EU27 countries, we estimated the total annual number of cases of leukaemia attributable to ELF MF at between ~50 (95% CIs: -14, 132) and ~60 (95% CIs: -9, 610), depending on whether exposure-response was modelled categorically or continuously, respectively, for a non-threshold effect. This corresponds to between ~1.5% and ~2.0% of all incident cases of childhood leukaemia occurring annually in the EU27. Considerable uncertainties are due to scarce data on exposure and the choice of exposure-response model, demonstrating the importance of further research into better understanding mechanisms of the potential association between ELF MF exposure and childhood leukaemia and the need for improved monitoring of residential exposures to ELF MF in Europe.

Symptom attribution and risk perception in individuals with idiopathic environmental intolerance to electromagnetic fields and in the general population

Aim:

To investigate differences in health perception and electromagnetic fields (EMF) between people within the general population reporting sensitivity or non-sensitivity to EMF, and people who registered themselves as sensitive to EMF at a non-governmental organisation (NGO).

Methods:

Correlations and regression analysis to compare a sample of the general population recruited via internet panel to individuals with idiopathic environmental intolerance to EMF (IEI-EMF) recruited via an interest group.

Results:

The general population sensitive group was more similar to the non-sensitive group in personal characteristics than to the NGO sensitive group. They experienced more – and more frequent – non-specific symptoms, reported higher perceived risk of EMF, and attributed their symptoms more to EMF than the non-sensitive group, but less than the NGO sensitive group. There was a positive association between attribution of symptoms to EMF and reported intensity of non-specific symptoms, which was stronger for the NGO sensitive subjects than for the general population.

Conclusions:

People sensitive to EMF and recruited via an internet panel differ from people sensitive to EMF and recruited via an NGO, who reported a higher frequency of non-specific symptoms. Attribution of symptoms to EMF is one of the predictors of the intensity of physical symptoms. Changing the perceived association between EMF and health problems in individuals with IEI-EMF might contribute to a better health experience.

The value of environmental information without control of subsequent decisions

The standard value of information approach of decision analysis assumes that the individual or agency that collects the information is also in control of the subsequent decisions based on the information. We refer to this situation as the "value of information with control (VOI-C)." This paradigm leads to powerful results, for example, that the value of information cannot be negative and that it is zero, when the information cannot change subsequent decisions. In many real world situations, however, the agency collecting the information is different from the one that makes the decision on the basis of that information. For example, an environmental research group may contemplate to fund a study that can affect an environmental policy decision that is made by a regulatory organization. In this two-agency formulation, the information-acquiring agency has to decide, whether an investment in research is worthwhile, while not being in control of the subsequent decision. We refer to this situation as "value of information without control (VOI-NC)." In this article, we present a framework for the VOI-NC and illustrate it with an example of a specific problem of determining the value of a research program on the health effects of power-frequency electromagnetic fields. We first compare the VOI-C approach with the VOI-NC approach. We show that the VOI-NC can be negative, but that with high-quality research (low probabilities of errors of type I and II) it is positive. We also demonstrate, both in the example and in more general mathematical terms, that the VOI-NC for environmental studies breaks down into a sum of the VOI-NC due to the possible reduction of environmental impacts and the VOI-NC due to the reduction of policy costs, with each component being positive for low environmental impacts and high-quality research. Interesting results include that the environmental and cost components of the VOI-NC move in opposite directions as a function of the probability of environmental impacts and that VOI-NC can be positive, even though the probability of environmental impacts is zero or one.

Could the geomagnetic field be an effect modifier for studies of power-frequency magnetic fields and childhood leukaemia?

Epidemiological studies find an association between power-frequency magnetic fields and childhood leukaemia. One candidate mechanism for a causal link is effects of magnetic fields on biological reactions involving free radicals. This mechanism predicts effects from variations in static, as well as alternating, magnetic fields, and therefore different consequences at different locations on the earth's surface due to variations in geomagnetic field. Testing this directly is problematic. Instead, we investigate whether geomagnetic field appears to be an effect modifier in studies of alternating magnetic fields. We find some, but rather limited and not statistically significant, evidence for this, and discuss the implications.

Perception of health risks of electromagnetic fields by MRI radiographers and airport security officers compared to the general Dutch working population: a cross sectional analysis

BACKGROUND

The amount of exposure to electromagnetic fields (EMF) at work is mainly determined by an individual's occupation and may differ from exposure at home. It is, however, unknown how different occupational groups perceive possible adverse health effects of EMF.

METHODS

Three occupational groups, the general Dutch working population (n = 567), airport security officers who work with metal detectors (n = 106), and MRI radiographers who work with MRI (n = 193), were compared on perceived risk of and positive and negative feelings towards EMF in general and of different EMF sources, and health concerns by using analyses of variances. Data were collected via an internet survey.

RESULTS

Overall, MRI radiographers had a lower perceived risk, felt less negative, and more positive towards EMF and different sources of EMF than the general working population and the security officers. For security officers, feeling more positive about EMF was not significantly related to perceived risk of EMF in general or EMF of domestic sources. Feeling positive about a source did not generalize to a lower perceived risk, while negative feelings were stronger related to perceived risk. MRI radiographers had fewer health concerns regarding EMF than the other two groups, although they considered it more likely that EMF could cause physical complaints.

CONCLUSIONS

These data show that although differences in occupation appear to be reflected in different perceptions of EMF, the level of occupational exposure to EMF as such does not predict the perceived health risk of EMF.

Exploring exposure--response for magnetic fields and childhood leukemia

For 30 years, there have been suggestions that extremely low frequency magnetic fields such as those are produced by electric power systems may be associated with elevated risks of childhood leukemia. These suggestions are driven by epidemiological evidence, and it has been common to characterize that evidence as showing a threshold effect, with no increase in risk below a threshold, often 0.3 or 0.4 μT, and a constant risk above it. Such a threshold would, however, be biologically unlikely. We tested alternative dose-response relationships quantitatively. We obtained five exposure data sets, applied several candidate dose-response relationships to each one, and performed a regression analysis to see how well they fit each of the three epidemiological data sets. Threshold dose-response relationships performed only moderately. Linear relationships were generally even poorer. The fit was improved by adding quadratic terms or performing non-linear regression. There are limitations in our analysis, stemming from the available data, but addressing this issue in a data-based, quantitative manner should improve understanding, allow better calculations to be made of attributable numbers, and hence ultimately inform public policy making.

Risk governance for mobile phones, power lines, and other EMF technologies

Power-frequency electric and magnetic fields (EMFs) have been present in industrialized countries since the late 19th century and a considerable amount of knowledge has been accumulated as to potential health effects. The mainstream scientific view is that even if there is a risk, it is unlikely to be of major public-health significance. EMFs from cellular communications and other radio-frequency technologies have increased rapidly in the last decade. This technology is constantly changing, which makes continued research both more urgent and more challenging. While there are no persuasive data suggesting a health risk, research and particularly exposure assessment is still immature. The principal risk-governance issue with power frequencies is how to respond to weak and uncertain scientific evidence that nonetheless causes public concern. For radio-frequency electromagnetic fields, the issue is how to respond to large potential consequences and large public concern where only limited scientific evidence exists. We survey these issues and identify deficits in risk governance. Deficits in problem framing include both overstatement and understatement of the scientific evidence and of the consequences of taking protective measures, limited ability to detect early warnings of risk, and attempted reassurance that has sometimes been counterproductive. Other deficits relate to the limited public involvement mechanisms, and flaws in the identification and evaluation of tradeoffs in the selection of appropriate management strategies. We conclude that risk management of EMFs has certainly not been perfect, but for power frequencies it has evolved and now displays many successful features. Lessons from the power-frequency experience can benefit risk governance of the radio-frequency EMFs and other emerging technologies.

Exposure to 50 Hz magnetic field in apartment buildings with built-in transformer stations in Hungary

Exposure to 50 Hz magnetic field (MF) was evaluated in 31 multi-level apartment buildings with built-in step-down transformer stations. In each building, three apartments were selected: one apartment located immediately above the transformer room (index apartment), one located on the same floor and one on a higher floor. The mean value of measured MFs was 0.98 microT in apartments above transformers, 0.13 microT on the same floor, and 0.1 microT in on higher floors. The mean measured MF value was higher than 0.2 microT in 30 (97%) index apartments, 4 (14%) on the same floor as the index apartments and 4 (13%) on higher floors. The corresponding numbers were 25 (81%), 0 and 0, respectively, when 0.4 microT was used as cut-point. It is concluded that apartments in building with built-in transformers can be reliably classified into high and low-exposure categories based on their location in relation to transformers.

Monitoring of people and workers exposure to the electric, magnetic and electromagnetic fields in an Italian National Cancer Institute

Background

The paper reports the electric, magnetic and electromagnetic fields (emf) measurements carried out in the Regina Elena National Cancer Institute (NCI). Several devices, used in diagnostics and in medical cures, can represent sources of emf for the workers and for the public subjected to the treatments. The aim is to evaluate their exposition, in order to assess the compliance with the law.

Methods

The investigations have been carried out in the departments of: intensive care, physiotherapy, MR presstherapy and in the surgical rooms. The measurements have been performed using broad band probes in the frequency ranges 5 Hz÷30 kHz and 100 kHz-3 GHz.

Results

The variability of the magnetic induction (B(μT)) levels is between 0,05 μT and 80 μT. The statistical distribution shows that most of the measurements are in the range 0,05<B = 0,5 μT and the 89% of the B(μT) levels are within the 3 μT.

Conclusion

The measurement of the emf levels in the NCI is recommended because of the presence of the oncological patients; their long stay near the equipments and their day-long exposure represent additional risk factors for which a prudent avoidance strategy have to de adopted.

Exposure to electromagnetic fields and the risk of childhood leukaemia: a review

Extremely low-frequency magnetic fields have been classified as possibly carcinogenic to humans, mainly based on epidemiological studies consistently showing an association between long-term average exposures to magnetic fields above 0.3/0.4 microT and the risk of childhood leukaemia. No mechanism to explain this finding has been established and no support for a causal link emerged from experimental studies. Chance or bias cannot be ruled out with reasonable confidence as an explanation for the observed association. If the association is causal, it explains only a small fraction of childhood leukaemia cases. There were some reports of childhood leukaemia clusters in the vicinity of high-power radio and television broadcast transmitters in studies in Australia and Italy. However, recent large-scale systematic studies in Korea and Germany show no association between exposure to radio frequency electromagnetic fields emitted from broadcast towers and childhood leukaemia risk. Studies on mobile phone use and leukaemia risk in adolescents and young adults may be indicated.

Biological effects from electromagnetic field exposure and public exposure standards

During recent years there has been increasing public concern on potential health risks from power-frequency fields (extremely low frequency electromagnetic fields; ELF) and from radiofrequency/microwave radiation emissions (RF) from wireless communications. Non-thermal (low-intensity) biological effects have not been considered for regulation of microwave exposure, although numerous scientific reports indicate such effects. The BioInitiative Report is based on an international research and public policy initiative to give an overview of what is known of biological effects that occur at low-intensity electromagnetic fields (EMFs) exposure. Health endpoints reported to be associated with ELF and/or RF include childhood leukaemia, brain tumours, genotoxic effects, neurological effects and neurodegenerative diseases, immune system deregulation, allergic and inflammatory responses, breast cancer, miscarriage and some cardiovascular effects. The BioInitiative Report concluded that a reasonable suspicion of risk exists based on clear evidence of bioeffects at environmentally relevant levels, which, with prolonged exposures may reasonably be presumed to result in health impacts. Regarding ELF a new lower public safety limit for habitable space adjacent to all new or upgraded power lines and for all other new constructions should be applied. A new lower limit should also be used for existing habitable space for children and/or women who are pregnant. A precautionary limit should be adopted for outdoor, cumulative RF exposure and for cumulative indoor RF fields with considerably lower limits than existing guidelines, see the BioInitiative Report. The current guidelines for the US and European microwave exposure from mobile phones, for the brain are 1.6 W/Kg and 2 W/Kg, respectively. Since use of mobile phones is associated with an increased risk for brain tumour after 10 years, a new biologically based guideline is warranted. Other health impacts associated with exposure to electromagnetic fields not summarized here may be found in the BioInitiative Report at www.bioinitiative.org.