Biological effects of exposure to static electric fields in humans and vertebrates: a systematic review

Whole-Body Electrostatic Pain Treatment in Adults with Chronic Pain: A Prospective Multicentric Observational Clinical Trial

INTRODUCTION

In the treatment of patients with chronic pain, whole-body electrostatic therapy using the Elosan Cabin C1 has been proposed as an adjunctive therapy. So far, data on the use of this cabin are limited. Promising results with a significant reduction in pain scores have been obtained in a small group of patients. However, treatment with Elosan Cabin C1 has not been the subject of evaluation in a larger patient population. The aim of this study was to investigate the efficacy and adverse effects of electrostatic treatment in such a population.

METHODS

Prospective, multi-center, observational clinical trial conducted in daily practice in a large adult ambulatory population with chronic pain. Each patient received eight weekly Elosan C1 treatment sessions for up to 9 weeks. Treatment was added to an established conservative pain management. Pain scores (visual analog scale (VAS) 0-100, primary outcome) and sleep quality (seven-point Likert scale, secondary outcome) were assessed before, during, and at the end of the treatment period; quality of life (SF-12: Physical Component Summary = PCS, Mental Component Summary = MCS; secondary outcome) was assessed before and at the end of the treatment period. Subgroup analyses were performed for sex, age, duration of pain, initial pain location, pain entity, and pain medication at the start of treatment.

RESULTS

A total of 192 patients were enrolled, 143 patients (74.5%) had a complete set of 8 treatment sessions. A reduction in pain scores from 68 ± 14 points to 47 ± 22 points was observed (p < 0.001), 65% of patients (responders) had a reduction of > 15 points. Female patients had a significantly better response than male patients with a higher number of responders (76% vs. 38%; p < 0.001). Patients with a pain history < 1 year had a significantly better response than patients with a pain history > 1 year. The Physical Component Summary (PCS) increased from 36 ± 11 to 41 ± 11 (+ 18%, p < 0.001) and the Mental Component Summary (MCS) from 41 ± 7 to 43 ± 7 (+ 6%, p = 0.3). Overall sleep quality improved significantly from 4.6 ± 1.7 to 3.73 ± 1.7 points (p < 0.001), with a higher proportion of responders in the female group (37 vs. 18%; p < 0.034). No serious adverse events were observed during treatment.

CONCLUSIONS

Electrostatic therapy with Elosan Cabin C1 may be a useful and effective adjunct therapy for patients with chronic pain. The results suggest that female patients and those with a recent history of pain experience the greatest benefit.

TRIAL REGISTRATION

NCT04818294 (clinicaltrials.gov).

Directionally non-rotating electric field therapy delivered through implanted electrodes as a glioblastoma treatment platform: A proof-of-principle study

Background

While directionally rotating tumor-treating fields (TTF) therapy has garnered considerable clinical interest in recent years, there has been comparatively less focus on directionally non-rotating electric field therapy (dnEFT).

Methods

We explored dnEFT generated through customized electrodes as a glioblastoma therapy in in vitro and in vivo preclinical models. The effects of dnEFT on tumor apoptosis and microglia/macrophages in the tumor microenvironment were tested using flow-cytometric and qPCR assays.

Results

In vitro, dnEFT generated using a clinical-grade spinal cord stimulator showed antineoplastic activity against independent glioblastoma cell lines. In support of the results obtained using the clinical-grade electrode, dnEFT delivered through a customized, 2-electrode array induced glioblastoma apoptosis. To characterize this effect in vivo, a custom-designed 4-electrode array was fabricated such that tumor cells can be implanted into murine cerebrum through a center channel equidistant from the electrodes. After implantation with this array and luciferase-expressing murine GL261 glioblastoma cells, mice were randomized to dnEFT or placebo. Relative to placebo-treated mice, dnEFT reduced tumor growth (measured by bioluminescence) and prolonged survival (median survival gain of 6.5 days). Analysis of brain sections following dnEFT showed a notable increase in the accumulation of peritumoral macrophage/microglia with increased expression of M1 genes (IFNγ, TNFα, and IL-6) and decreased expression of M2 genes (CD206, Arg, and IL-10) relative to placebo-treated tumors.

Conclusions

Our results suggest therapeutic potential in glioblastoma for dnEFT delivered through implanted electrodes, supporting the development of a proof-of-principle clinical trial using commercially available deep brain stimulator electrodes.

Systematic review of the physiological and health-related effects of radiofrequency electromagnetic field exposure from wireless communication devices on children and adolescents in experimental and epidemiological human studies

BACKGROUND

For more than 20 years, the potential health risks of radiofrequency electromagnetic field (RF EMF) exposure from mobile communication devices on children and adolescents have been examined because they are considered sensitive population groups; however, it remains unclear whether such exposure poses any particular risk to them.

OBJECTIVES

The aim of this review was to systematically analyze and evaluate the physiological and health-related effects of RF EMF exposures from wireless communication devices (mobile phones, cordless phones, Bluetooth, etc.) on children and adolescents.

METHODS

This review was prepared according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Methodological limitations in individual studies were assessed using the Office of Health Assessment and Translation (OHAT) Risk-of-Bias Rating Tool for Human and Animal Studies.

RESULTS

A total of 42 epidemiological and 11 experimental studies were eligible for this review. Most of the studies displayed several methodological weaknesses that limited the internal validity of the results. Due to a lack of consistency regarding the outcomes as well as the lack of scientific rigor in most reviewed studies, the body of evidence for the effects of RF EMF of mobile communication devices on subjective symptoms, cognition, and behavior in children and adolescents was low to inadequate. Evidence from the studies investigating early childhood development, brain activity, cancer, and physiological parameters was considered inadequate for drawing conclusions about possible effects.

DISCUSSION

Overall, the body of evidence allows no final conclusion on the question whether exposure to RF EMF from mobile communication devices poses a particular risk to children and adolescents. There has been rapid development in technologies generating RF EMF, which are extensively used by children and adolescents. Therefore, we strongly recommend high-quality systematic research on children and adolescents, since they are generally considered as sensitive age groups.

A Parallel Resonant Converter Polynomial Model Implemented in a Digital Signal Controller

Due to their exceptional performance in coping with large variations in output voltage and current, parallel resonant converters (PRC) are commonly used in high-voltage applications. The incorporation of step-up transformer parasitic components as part of a power topology, on the right duty and a suitable switching frequency, determines the high efficiency and wide variety of applications with PRC. Switching losses are reduced in the same topology by tracking and running on the optimum mode for each power and voltage by a set frequency and duty. The PRC’s static model behaviors, under optimum operating circumstances, are illustrated. The equivalent polynomial model is used to quickly compute the switching frequency and duty cycle required to achieve the converter’s desired output voltage and power. The polynomial model is simple and easy to implement in any form of a digital signal controller (DSC). Normalized parameters are used to widen the operational range and generalize the model. This also offers the essential protection against current and voltage spikes. The work in progress depicts the specific procedures involved in developing a polynomial model. The normalized equations provide a graphical description of the static model, from which the graphical representation of the polynomial are derived. Hence, polynomial equations are obtained. This paper describes the PRC static model, how to convert it to a polynomial model, how to validate it with MATLAB-Simulink, how to program F28335 using Simulink, and how to use it in practice.

The role of the AC component in human perception of AC-DC hybrid electric fields

Electric energy is essential to today’s society. To cope with global higher demand while minimizing land use, efficient high voltage direct current (HVDC) power lines are planned to be mounted on existing alternating current (AC) structures leading to electric fields (EFs) from both AC and DC transmission lines in hybrid configurations. Due to the close proximity to residential areas, the investigation of human hybrid EF perception and underlying mechanisms will be useful to project permitting. To specify the influence of the AC component on the whole-body detection thresholds of hybrid EFs and to explore the lower bound of human hybrid EF perception, 51 participants with an EF detection ability above average were exposed in a double-blind laboratory study. A psychophysical method based on the signal detection theory was used. Very low EF strength combinations, e.g. 1 kV/m AC combined with 1 kV/m DC, were reliably perceived by at least one participant. Detection thresholds were significantly lower with increased AC EF strengths, underlining the key role of the AC component in the human perception of hybrid EFs. Findings will contribute to the assessment of public reaction to the perception of EFs around hybrid overhead power lines and to their optimal designs.

The ecology of electricity and electroreception

Electricity, the interaction between electrically charged objects, is widely known to be fundamental to the functioning of living systems. However, this appreciation has largely been restricted to the scale of atoms, molecules, and cells. By contrast, the role of electricity at the ecological scale has historically been largely neglected, characterised by punctuated islands of research infrequently connected to one another. Recently, however, an understanding of the ubiquity of electrical forces within the natural environment has begun to grow, along with a realisation of the multitude of ecological interactions that these forces may influence. Herein, we provide the first comprehensive collation and synthesis of research in this emerging field of electric ecology. This includes assessments of the role electricity plays in the natural ecology of predator-prey interactions, pollination, and animal dispersal, among many others, as well as the impact of anthropogenic activity on these systems. A detailed introduction to the ecology and physiology of electroreception - the biological detection of ecologically relevant electric fields - is also provided. Further to this, we suggest avenues for future research that show particular promise, most notably those investigating the recently discovered sense of aerial electroreception.

Potential factors affecting chronic chemical intolerance associated with constitutional predisposition or lifestyle and environment during childhood: From a six-year follow-up study

OBJECTIVE

The Japanese chemical intolerance (JCI) study was conducted in January 2012 with a cohort of 7245 adults from population-based sampling. This study aimed to investigate the childhood constitutional and environmental factors involved in the development of chronic CI from the prospective cohort study.

METHODS

In the cohort, 4683 persons were identified after six years. Self-reported questionnaires were administered to the subjects to obtain information on CI status; medical history; constitution, lifestyle, and housing environment during childhood; and recent psychosomatic states. We assessed the differences between individuals with persisting CI status during the follow-up (defined as chronic CI) and controls not having CI status during the follow-up.

RESULTS

A total of 2500 individuals responded. Multiple logistic regression analyses revealed significant associations between chronic CI and motion sickness to car or bus and allergic conjunctivitis during childhood. Significant associations between a possible increased risk of CI and the existence of high-voltage power lines close to housing, the use of vinyl covering in wall material, the use of strong perfume by a family member, and the experience of stinky odor of paint or wax at elementary school were observed. However, the use of carpet in floor material and plaster coating in wall material was associated with a possible decreased risk of CI.

CONCLUSIONS

Some potential constitutional predisposition from childhood, including inherent susceptibility in the autonomic nervous system may be involved in the development of CI.

Human detection thresholds of DC, AC, and hybrid electric fields: a double-blind study

BACKGROUND

In the course of the ongoing transition of electric energy systems, transmission corridors are often upgraded to higher voltages and other technologies leading to another quality of human exposure. The study aims to determine human detection thresholds for direct current (DC), alternating current (AC), and hybrid electric fields (various DC; constant AC).

METHODS

A total of 203 participants were exposed to DC, AC, and hybrid electric fields (EFs) in a highly specialized whole-body exposure laboratory using a double-blind experimental setting. Additionally, the participants were exposed to ion currents in part of the DC and hybrid sessions. To investigate environmental influences, relative humidity was changed in two subgroups during EF perception. Methods derived from the signal detection theory and the adaptive staircase procedure based on the single interval adjustment matrix were used to assess individual sensitivity and detection thresholds, respectively.

RESULTS

The results indicated that detection thresholds of hybrid EF were lower compared to single EF presentation of DC or AC. Ion current exposure enhanced EF perception. High relative humidity facilitated DC EF perception, whereas low relative humidity reinforced the perception of AC EFs.

CONCLUSIONS

With this systematic investigation of human perception of DC, AC, and hybrid EFs, detection thresholds were provided, which can help improve the construction processes of energy transmission systems and the prevention of unwanted sensory perception by contributing to the determination of limit values.

Testosterone synthesis in testicular Leydig cells after long-term exposure to a static electric field (SEF)

China's clean energy and resources are mainly located in the west and north while electric load center is concentrated in the middle and east. Thus, these resources and energy need to be converted into electrical energy in situ and transported to electric load center through ultra-high voltage direct current (UHVDC) transmissions. China has built 25,000 km UHVDC transmission lines of 800 kV and 1100 kV, near which the impact of electric field on health has attracted public attention. Previous studies showed that time-varying electromagnetic field exposure could disturb testosterone secretion. To study the effect of non-time-varying electric field caused by direct current transmission lines on testosterone synthesis, male ICR mice were continually (24 h/d) exposed to static electric field of 56.3 ± 1.4 kV/m. Results showed that on the 3^rd day of exposure and on the 7^th day after ceasing the exposure of 28 d, serum testosterone level and testicular oxidative stress indicators didn't change significantly. On the 28^th day of exposure, serum testosterone levels, testicular glutathione peroxidase (GSH-Px) activity, the mRNA and protein levels of testicular StAR, PBR, CYP11A1 decreased significantly, and testicular malondialdehyde (MDA) content increased significantly. Meanwhile, electron-dense edges and vacuolation appeared in lipid droplets of Leydig cells. The gap between inner mitochondrial membrane (IMM) and outer mitochondrial membrane (OMM) enlarged, which would cause the swelling of mitochondria, the rupture and deficiency of mitochondrial membranes. Analysis showed that testicular oxidative stress could induce the damage of mitochondrial structure in Leydig cells, which would decrease the rate of cholesterol transport from cytoplasm to mitochondria. Since cholesterol is the necessary precursor of testosterone synthesis, testosterone synthesis was inhibited. The decrease of the mRNA and protein expression levels of StAR and PBR in testes could diminish the cholesterol transported from OMM to IMM. The decrease of the mRNA and protein expression levels of CYP11A1 could reduce the pregnenolone required in testosterone synthesis and inhibit testosterone synthesis consequently.

Identification of Environmental and Experimental Factors Influencing Human Perception of DC and AC Electric Fields

As part of the energy transition in Germany, high-voltage direct current (HVDC) lines producing DC electric fields (EF) are in planning. Since the human perception of DC EF was rarely investigated in the past, we aimed to identify environmental and experimental factors influencing the human perception of direct current (DC) EF, alternating current (AC) EF, and the co-exposure of DC EF and AC EF (hybrid EF) under whole-body exposure. Additionally, first estimates of DC EF and AC EF perception thresholds as well as differences in human perception of DC EF and AC EF concerning the type of sensation experienced and the affected body part were evaluated. A highly sophisticated exposure lab was built to expose participants to various EF strengths and ask for their assessment concerning the presence of an EF. To estimate the individual perception thresholds of 11 participants, the signal detection theory as well as the single-interval-adjustment matrix procedure were applied. Relative humidity could be identified as an environmental factor influencing the perception of AC EF and DC EF in different ways. An appropriate ramp slope and an exposure duration for future studies could be elaborated. Additionally, perception thresholds were lower under hybrid EF exposure than under DC EF or AC EF exposure alone. Cutaneous sensations evoked under DC EF and AC EF exposure were individually different and attributed to various parts of the body. Several environmental and experimental factors influencing the human perception of EF could be identified and provide an essential basis for a large-scale study. © 2021 Bioelectromagnetics Society.

Electrostatic Discharge Causing Pump Shutdown in HeartMate 3

Left ventricular assist devices (LVADs) improve symptoms and outcomes in advanced heart failure. Although device malfunction has decreased significantly with later generation LVADs, it has not been eliminated. We describe the clinical course of a patient with HeartMate 3 LVAD who experienced device malfunction, involving temporary pump shutdown suspected to be caused by electrostatic discharge. (Level of Difficulty: Advanced.).

Application of multi-component fluid model in studies of the origin of skin burns during electrosurgical procedures

This paper reports on safety challenges regarding spark created when the applied electric field exceeds the dielectric breakdown strength as a source of complication during electrosurgery. Despite the unquestionable benefits of electrosurgery, such as minimal chances of infection and fast recovery time, the interaction of the electrosurgical tool with the tissue may result in tissue damage and force feedback to the tool. Some risks of complications often depend on a surgeon's knowledge of instruments and safety aspects of technical equipment that can be eliminated by clarifying the causation and conditions of their development. Current trends in electrosurgery include computational algorithms and methods to control the effect of delivered energy to the patient. For this study, calculations were performed by using the COMSOL simulation package based on a multi-component plasma fluid model. The emphasis is put on conditions that lead to the breakdown of the dielectric medium. It was found that breakdown occurs most easily when both electrodes are cylindrical. For configurations with one or two spherical electrodes, breakdown voltages are higher up to 25% and 48%, respectively. With decreasing the cathode radius, the breakdown voltage may decrease even to 41%. On the other hand, the temperature increase lowers the breakdown voltage. Also, electrical asymmetries appear to be a response to the non-symmetry of the electric field between the electrodes causing differences in the breakdown voltage between 36% and 70%. The results presented here could be very useful for the design of surgical devices to prevent potential complications of electrosurgical procedures.

Cytotoxic T cells response with decreased CD4/CD8 ratio during mammary tumors inhibition in rats induced by non-contact electric fields

Background: Breast cancer is the most common cancer in women worldwide and is the leading cause of death in women with cancer. One novel therapy used for breast cancer treatment is non-contact electric fields called electro-capacitive cancer therapy (ECCT) with intermediate frequency (100 kHz) and low intensity (18 Vpp). The objective of this study was to examine the effect of ECCT on mammary tumors growth in rats and observing the immune responses that play a role in fighting the tumor. Methods: Female SD rats were used and divided into four groups, namely control (NINT), placebo (NIT), non- therapy (INT), and therapy (IT) groups with 6 biological replicates in each group. Rats in INT and IT groups were treated with 7,12-dimethylbenz[a]anthracene for mammary tumor induction. Only rats in NIT and IT groups were exposed to ECCT individually for 10 hours per day for 21 days. The size of all tumors was measured with a digital caliper. The distributions of PCNA, ErbB2, caspase-3, CD68, CD4 and CD8-positive cells were observed with immunohistochemistry and scoring with ImageJ. Results: The growth rate of mammary tumors in IT group was significantly lower (p<0.05) than that in the INT group. The number of mitotic figures and the percentage of PCNA, caspase-3, and CD68- positive cells in IT group were significantly lower (p<0.05) than those in INT group. Conversely, the percentage of CD8-positive T cells in IT group was significantly higher (p<0.05) than that in INT group. Moreover, the CD4/CD8 ratio in IT group was decreased. Some tumor tissues were blackened and detached from the surrounding tissue, resulting in an open wound which then healed up upon exposure. Conclusions: Non-contact electric fields exposure showed inhibition on mammary tumor growth in rats while inducing CD8+ T cells that lead to tumor cells death and potentially helps wound healing.

Cytotoxic T cells response with decreased CD4/CD8 ratio during mammary tumors inhibition in rats induced by non-contact electric fields

Background: Breast cancer is the most common cancer in women worldwide and is the leading cause of death amongst women with cancer. One novel therapy used for breast cancer treatment constitutes non-contact electric fields and is called electro-capacitive cancer therapy (ECCT) with intermediate frequency and low intensity. The objective of this study was to examine the effect of ECCT on mammary tumors growth in rats and observing the immune responses that play a role in fighting the tumor. Methods: Female SD rats were used and divided into four groups, namely control (NINT), placebo (NIT), non- therapy (INT), and therapy (IT) groups with 6 biological replicates in each group. Rats in INT and IT groups were treated with 7,12-dimethylbenz[a]anthracene for mammary tumor induction. Only rats in NIT and IT groups were exposed to ECCT individually for 10 hours per day for 21 days. The size of all tumors was measured with a digital caliper. The distributions of PCNA, ErbB2, caspase-3, CD68, CD4, and CD8-positive cells were observed with immunohistochemistry and scoring with ImageJ. Results: The growth rate of mammary tumors in IT group was significantly lower (p<0.05) than that in INT group. The number of mitotic figures and the percentage of PCNA, caspase-3, and CD68-positive cells in IT group were significantly lower (p<0.05) than those in INT group. Conversely, the percentage of CD8-positive T cells in IT group was significantly higher (p<0.05) than that in INT group. Moreover, the CD4/CD8 ratio in IT group was found to have decreased. Some tumor tissues were blackened and detached from the surrounding tissue, resulting in an open wound which then healed upon exposure. Conclusions: Non-contact electric fields exposure showed inhibition on mammary tumor growth in rats while inducing CD8+ T cells, leading to tumor cell death and potentially helping wounds heal.

Possible molecular and cellular mechanisms at the basis of atmospheric electromagnetic field bioeffects

Mechanisms of how electromagnetic (EM) field acts on biological systems are governed by the same physics regardless of the origin of the EM field (technological, atmospheric...), given that EM parameters are the same. We draw from a large body of literature of bioeffects of a man-made electromagnetic field. In this paper, we performed a focused review on selected possible mechanisms of how atmospheric electromagnetic phenomena can act at the molecular and cellular level. We first briefly review the range of frequencies and field strengths for both electric and magnetic fields in the atmosphere. Then, we focused on a concise description of the current knowledge on weak electric and magnetic field bioeffects with possible molecular mechanisms at the basis of possible EM field bioeffects combined with modeling strategies to estimate reliable outcomes and speculate about the biological effects linked to lightning or pyroelectricity. Indeed, we bring pyroelectricity as a natural source of voltage gradients previously unexplored. While very different from lightning, it can result in similar bioeffects based on similar mechanisms, which can lead to close speculations on the importance of these atmospheric electric fields in the evolution.

Challenges in coupling atmospheric electricity with biological systems

The atmosphere is host to a complex electric environment, ranging from a global electric circuit generating fluctuating atmospheric electric fields to local lightning strikes and ions. While research on interactions of organisms with their electrical environment is deeply rooted in the aquatic environment, it has hitherto been confined to interactions with local electrical phenomena and organismal perception of electric fields. However, there is emerging evidence of coupling between large- and small-scale atmospheric electrical phenomena and various biological processes in terrestrial environments that even appear to be tied to continental waters. Here, we synthesize our current understanding of this connectivity, discussing how atmospheric electricity can affect various levels of biological organization across multiple ecosystems. We identify opportunities for research, highlighting its complexity and interdisciplinary nature and draw attention to both conceptual and technical challenges lying ahead of our future understanding of the relationship between atmospheric electricity and the organization and functioning of biological systems.

The role of magnetic fields in neurodegenerative diseases

The term neurodegenerative diseases include a long list of diseases affecting the nervous system that are characterized by the degeneration of different neurological structures. Among them, Alzheimer disease (AD), Parkinson disease (PD), and amyotrophic lateral sclerosis (ALS) are the most representative ones. The vast majority of cases are sporadic and results from the interaction of genes and environmental factors in genetically predisposed individuals. Among environmental conditions, electromagnetic field exposure has begun to be assessed as a potential risk factor for neurodegeneration. In this review, we discuss the existing literature regarding electromagnetic fields and neurodegenerative diseases. Epidemiological studies in AD, PD, and ALS have shown discordant results; thus, a clear correlation between electromagnetic exposure and neurodegeneration has not been demonstrated. In addition, we discuss the role of electromagnetic radiation as a potential non-invasive therapeutic strategy for some neurodegenerative diseases, particularly for PD and AD.

Direct Differentiation of Human Primary Fibroblast into Hematopoietic-Like Stem Cells; A New Way without Viral Transduction

Objective

The aim of this study was to investigate the possibility of producing safe hematopoietic stem cells without the use of viral infectious agents that can be used in stem cell transplantation.

Materials and Methods

In this experimental study, after single layer cell formation, human primary fibroblast cells were treated with static electromagnetic fields of 10 and 15 milli Tesla (mT) for 20 minutes each day for seven consecutive days. On the seventh day and immediately after the last radiation, the cells were added to the wells containing specific hematopoietic stem cell expansion media. After 21 days and colony formation, the cells belonging to each group were evaluated in terms of the expression of CD34, CD38, and GATA-1 genes using quantitative real-time polymerase chain reaction (PCR), as well as surface marker expression of CD34 by flow cytometry.

Results

Exposure to 10 mT and 15 mT electromagnetic field increased the expression of CD34 and CD38 genes (P<0.05). This increase in gene expression levels were 2.85 and 1.84 folds, respectively, in the 10mT group and 6.36 and 3.81 folds, respectively, in the 15 mT group. The expression of the GATA-1 gene in the 10 mT and 15 mT groups was not significantly different from that of the control group (P<0.05). Electromagnetic waves caused a marked increase in the expression of the CD34 marker at the surface of reprogrammed cells. The rate of expression was about 42.3% in the 15 mT group and 23.1% in the 10 mT group.

Conclusion

The presence of human primary fibroblasts exposed to electromagnetic fields can increase the expression of specific hematopoietic genes. This method can be suitable for reprogramming cells differentiated into hematopoietic- like stem cells and does not pose the risks of retroviral use.

Biological and health-related effects of weak static magnetic fields (≤ 1 mT) in humans and vertebrates: A systematic review

BACKGROUND

There is a rapid development in technologies that generate weak static magnetic fields (SMF) including high-voltage direct current (HVDC) lines, systems operating with batteries, such as electric cars, and devices using permanent magnets. However, few reviews on the effects of such fields on biological systems have been prepared and none of these evaluations have had a particular focus on weak SMF (≤ 1 mT). The aim of this review was to systematically analyze and evaluate possible effects of weak SMF (≤ 1 mT) on biological functioning and to provide an update on the current state of research.

METHODS

This review was prepared in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Methodological limitations in individual studies were assessed using the Office of Health Assessment and Translation (OHAT) Risk-of-Bias Rating Tool.

RESULTS

Eleven studies fulfilled the eligibility criteria and were included in this review. All included studies were experimental animal studies as no human studies were among the eligible articles. Eight of the eleven studies reported responses of rat, rabbits and quails to weak SMF exposure that were expressed as altered melatonin biosynthesis, reduced locomotor activity, altered vasomotion and blood pressure, transient changes in blood pressure-related biochemical parameters, or in the level of neurotransmitters and increases in enzyme activities. It remained largely unclear from the interpretation of the results whether the reported effects in the evaluated studies were beneficial or detrimental for health.

CONCLUSION

The available evidence from the literature reviewed is not sufficient to draw a conclusion for biological and health-related effects of exposure to weak SMF. There was a lack of homogeneity regarding the exposed biological systems and the examined endpoints as well as a lack of scientific rigor in most reviewed studies which lowered credibility in the reported results. We therefore encourage further and more systematic research in this area. Any new studies should particularly address effects of exposure to SMF on biological functioning in humans to evaluate whether SMF pose a risk to human health.

Effects of continuous exposure to power frequency electric fields on soybean Glycine max

With the increasing density of high voltage transmission systems, the potential risks and hazards of environmental electric fields (EFs) generated by these systems to surrounding organisms is becoming a source of public concern. To evaluate the effect of environmental EFs on plants, we used soybean as a model and systematically evaluated the effect of continuous exposure to different intensities (0 kV/m, 2 kV/m, and 10 kV/m) of power frequency EFs on agronomic characters, yield, nutrient contents, protective enzyme activities, and gene transcription. We found that the effects on soybean were more pronounced when plants were exposed to EF during development (especially at the seedling stage) than when they were exposed at maturity. The functional leaf number, stem diameter, plant dry weight, and pod number were largely unaffected by EF, while the germination rate and protective enzyme activities increased with increasing EF intensity. In plants exposed to low-intensity EF (2 kV/m), some agronomic characters, including chlorophyll content, plant height, and bean dry weight, as well as the soluble sugar and total protein contents, were significantly higher than those of plants exposed to high-intensity EF (10 kV/m) and control plants (0 kV/m). Through transcriptome analysis, we found that 2,977 genes were significantly up-regulated and 1,462 genes were down-regulated when plants were exposed to EF. These differentially expressed genes mainly encode ribosome proteins and related enzymes involved in carbon metabolism pathway, providing a novel perspective for understanding molecular mechanisms underpinning the responses to EF stress in soybean.

Atmospheric Electricity Influencing Biogeochemical Processes in Soils and Sediments

The Earth’s subsurface represents a complex electrochemical environment that contains many electro-active chemical compounds that are relevant for a wide array of biologically driven ecosystem processes. Concentrations of many of these electro-active compounds within Earth’s subsurface environments fluctuate during the day and over seasons. This has been observed for surface waters, sediments and continental soils. This variability can affect particularly small, relatively immobile organisms living in these environments. While various drivers have been identified, a comprehensive understanding of the causes and consequences of spatio-temporal variability in subsurface electrochemistry is still lacking. Here we propose that variations in atmospheric electricity (AE) can influence the electrochemical environments of soils, water bodies and their sediments, with implications that are likely relevant for a wide range of organisms and ecosystem processes. We tested this hypothesis in field and laboratory case studies. Based on measurements of subsurface redox conditions in soils and sediment, we found evidence for both local and global variation in AE with corresponding patterns in subsurface redox conditions. In the laboratory, bacterial respiratory responses, electron transport activity and H₂S production were observed to be causally linked to changes in atmospheric cation concentrations. We argue that such patterns are part of an overlooked phenomenon. This recognition widens our conceptual understanding of chemical and biological processes in the Earth’s subsurface and their interactions with the atmosphere and the physical environment.

Systematic review on the biological effects of electric, magnetic and electromagnetic fields in the intermediate frequency range (300 Hz to 1 MHz)

BACKGROUND

Many novel technologies, including induction cookers or wireless power transfer, produce electric fields (EF), magnetic fields (MF) or electromagnetic fields (EMF) in the intermediate frequency (IF) range. The effects of such fields on biological systems, however, have been poorly investigated. The aim of this systematic review was to provide an update of the state of research and to evaluate the potential for adverse effects of EF, MF and EMF in the IF range (300 Hz to 1 MHz) on biological systems.

METHODS

The review was prepared in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Methodical limitations in individual studies were assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias Rating Tool for Human and Animal Studies.

RESULTS

Fifty-six studies exposing humans, animals or in vitro systems were eligible for this review. In these studies, many different endpoints were examined and most of the findings were obtained in studies with exposure to MF. For most endpoints, however, the reviewed studies yielded inconsistent results, with some studies indicating no effect and some linking IF exposure with adverse effects. In the majority of the included studies, the applied field strengths were above the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels for the general public and the applied frequencies were mainly below 100 kHz. Furthermore, many of the reviewed studies suffered from methodical limitations which lowered the credibility of the reported results.

CONCLUSION

Due to the large heterogeneity in study designs, endpoints and exposed systems, as well as the inconsistent results and methodical limitations in many studies, the quality of evidence for adverse effects remains inadequate for drawing a conclusion on investigated biological effects of IF fields for most endpoints. We recommend that in future studies, effects of EF, MF and EMF in the IF range should be investigated more systematically, i.e., studies should consider various frequencies to identify potential frequency-dependent effects and apply different field strengths, especially if threshold-dependent effects are expected. Priority should be given to the investigation of acute effects, like induction of phosphenes, perception, excitation of nerves or muscles and thermal effects. This would be an important step towards the validation of the reference levels recommended by ICNIRP. Furthermore, we recommend that any new studies aim at implementing high quality dosimetry and minimizing sources of risk of bias.

A comparative study on effects of static electric field and power frequency electric field on hematology in mice

With the development of the ultra high voltage transmission technology, the voltage level of transmission line rised. Accordingly, the strength of electric field in the vicinity of transmission line increased, thus possible health effects from electric field have caused many public attentions. In this study, in order to compare effects induced by static electric field (SEF) and power frequency electric field (PFEF) on immune function, Institute of Cancer Research (ICR) mice were exposed to 35 kV/m SEF (0 Hz) and PFEF (50 Hz),respectively. Several indicators of white blood cell, red blood cell as well as hemoglobin in peripheral blood were tested after exposure of 7, 14 and 21 days, respectively. There was no significant difference in any indicators under SEF exposure of 35 kV/m for 7d, 14d and 21d between experimental group and control group. Under the PFEF exposure of 35 kV/m, white blood cell count significantly reduced after exposure of 7d, 14d and 21d. Meanwhile, red blood cell count significantly reduced after exposure of 7d, and returned to normal level through the compensatory response of organism after exposure of 14d and 21d. Hemoglobin concentration significantly decreased only after exposure of 21d. Based on tested results of hematological indicators, SEF exposure of 35 kV/m did not affect immune functions in mice but PFEF exposure of 35 kV/m could cause a decline of immune function. This difference of effects from SEF and PFEF on immune function was possibly caused by the difference of the degree of molecular polarization and ion migration in organism under exposure of two kinds of electric fields.

Studies on effects of static electric field exposure on liver in mice

With the development of ultra-high-voltage direct-current transmission, the intensity of static electric field (SEF) under transmission lines increased, which has aroused public attention on its potential health effects. In order to examine effects of SEF exposure on liver, institute of cancer research mice were exposed to SEF with intensities of 27.5 kV/m, 34.7 kV/m and 56.3 kV/m, respectively. In each intensity of SEF exposure, a corresponding sham exposure group was used. Several indices relating to liver function (aspartate aminotransferase (AST) and alanine aminotransferase (ALT)) and oxidative stress (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA)) were tested after exposure of 7, 14, 21 and 35 days. Results showed that exposure to SEF with intensities of 27.5 kV/m and 34.7 kV/m for 35 days did not significantly influence any detected indices above. Under SEF exposure with intensity of 56.3 kV/m, the SOD activity in liver was significantly increased after exposure of 7 and 14 days. However, no significant increase was found in MDA content as well as the activities of AST and ALT between exposure group and sham exposure group during SEF exposure of 56.3 kV/m. It suggested that from three SEF intensities, only exposure to SEF with intensity of 56.3 kV/m (7 and 14 days) caused a temporary oxidative stress response in liver expressed by the increase in activity of SOD, but it did not produce oxidative damage. This biological effect may be related to the increase of mitochondrial membrane potential of hepatocytes caused by SEF exposure. When the membrane potential exceeds a threshold, Q cycle in mitochondria will be affected, which will result in an increase of superoxide anion concentration and ultimately an oxidative stress.

Duration-dependent effect of exposure to static electric field on learning and memory ability in mice

With the rapid development of ultra-high-voltage direct-current (UHVDC) transmission, the strength of environmental static electric field (SEF) around UHVDC transmission lines increased substantially, which has aroused widely public attention on the potential health effects of SEF. In this study, the effect of SEF exposure on learning and memory ability was investigated. Institute of Cancer Research mice were exposed to 56.3 kV/m SEF for a short term (7 days) or long term (49 days). Behaviors in the Morris water maze (MWM) test, hippocampal neurotransmitter contents, and oxidative stress indicators were examined. Results showed that short-term SEF exposure significantly prolonged escape latency and decreased the number of platform-site crossovers, as well as decreased the time spent in the target quadrant in the MWM test. Meanwhile, serotonin level and the ratio of glutamate level to γ-aminobutyric acid level changed significantly. Besides, malondialdehyde content and glutathione peroxidase activity increased significantly, while superoxide dismutase activity decreased significantly. After long-term SEF exposure, all indices above showed no significant differences between the SEF and sham exposure groups. These data indicated that short-term exposure to 56.3 kV/m SEF could cause abnormal neurotransmitter levels and oxidative stress in the hippocampus, which led to the decline in learning and memory ability. Under the condition of long-term exposure, the SEF-induced disturbances in neurotransmitter contents and redox balance were offset by the compensatory responses of mice, and thus, the learning and memory ability returned to normal level. The temporary and reversible decline in learning and memory ability was only a common biological effect of SEF rather than a health hazard.

Exposure of laboratory animals to small air ions: a systematic review of biological and behavioral studies

BACKGROUND

Air ions are molecules of air that have become ionized-that is, they have either lost or gained an electrical charge. Past speculation has suggested that exposure to positive air ions may be harmful to one's health, while exposure to negative air ions may be associated with beneficial health effects. Air ions arise from natural sources as well as direct-current transmission lines and commercial ionizers. Several recent clinical studies have suggested therapeutic effects of air ions on various types of depression at exposure levels 10- to 1000-fold higher than most previous human studies. The aim of this study was to assess the evidence from studies of laboratory animals for beneficial or adverse effects of air ions on health.

METHODS

Sixty-two studies (1935-2015) in nine topics areas were evaluated for quality and potential systematic bias by ARRIVE guidelines. Standardized mean differences or proportional differences between exposed and control groups were computed for 44 studies to quantitatively assess the strength of the evidence for exposure-related effects.

RESULTS

Many of the studies were conducted before 1990 and exhibited various reporting and methodological deficiencies, including small sample size, failure to control for the influence of potential confounding variables, lack of randomized assignment to treatment groups and blinded analyses, and statistical errors relating to treating group-exposed animals as individuals. The highest quality studies consistently reported no effects of exposure on any of the endpoints examined. There were no evident dose-response relationships within or across studies.

CONCLUSIONS

Experimental studies of laboratory animals exposed to positive and negative air ions for minutes to years over a five-log unit range of intensities did not suggest any consistent or reliable effects on measures of behavior, learning and memory, neurotransmitters, tracheal function, respiratory infection, cardiovascular function, reproduction and growth, carcinogenesis, or other health endpoints. These data do not provide evidence of adverse or beneficial effects of air ion exposure on health, and did not suggest any biological mechanism of interaction, except perhaps for mechanosensory stimulation of body surfaces by static electric fields at high air ion concentrations.

Systematic review of biological effects of exposure to static electric fields. Part II: Invertebrates and plants

BACKGROUND

The construction of high-voltage direct current (HVDC) lines for the long-distance transport of energy is becoming increasingly popular. This has raised public concern about potential environmental impacts of the static electric fields (EF) produced under and near HVDC power lines. As the second part of a comprehensive literature analysis, the aim of this systematic review was to assess the effects of static EF exposure on biological functions in invertebrates and plants and to provide the basis for an environmental impact assessment of such exposures.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was used to guide the methodological conduct and reporting.

RESULTS

Thirty-three studies - 14 invertebrate and 19 plant studies - met the eligibility criteria and were included in this review. The reported behavioral responses of insects and planarians upon exposure strongly suggest that invertebrates are able to perceive the presence of a static EF. Many other studies reported effects on physiological functions that were expressed as, for example, altered metabolic activity or delayed reproductive and developmental stages in invertebrates. In plants, leaf damage, alterations in germination rates, growth and yield, or variations in the concentration of essential elements, for example, have been reported. However, these physiological responses and changes in plant morphology appear to be secondary to surface stimulation by the static EF or caused by concomitant parameters of the electrostatic environment. Furthermore, all of the included studies suffered from methodological flaws, which lowered credibility in the results.

CONCLUSION

At field levels encountered from natural sources or HVDC lines (< 35kV/m), the available data provide reliable evidence that static EF can trigger behavioral responses in invertebrates, but they do not provide evidence for adverse effects of static EF on other biological functions in invertebrates and plants. At far higher field levels (> 35kV/m), adverse effects on physiology and morphology, presumably caused by corona-action, appear to be more likely. Higher quality studies are needed to unravel the role of air ions, ozone, nitric oxide and corona current on alterations in physiological functions and morphology.