Design and characterisation of a cell exposure system with high magnetic field homogeneity: RILZ coils

In vitro studies requiring controlled exposure to low-frequency electromagnetic fields employ exposure systems with different geometries and configurations, the Helmholtz configuration being one of the most widely used. This configuration has limitations in the homogeneity of the spatial distribution of the magnetic field intensity values. We present the design, manufacturing, and characterisation of a new coil system, called RILZ configuration, which improves the distribution of magnetic field intensity values in the three dimensions of space for three different heights in comparison with the traditional circular coils in Helmholtz configuration. In addition, a comparative study of the cellular response in CT2A cultures exposed to a magnetic field of 50 Hz and 100 µT for 48 hrs is performed with both exposure systems. The results of the study show reduced values of deviation from the central value of magnetic field intensity using the RILZ coil system. These differences are statistically significant compared to the Helmholtz configuration for the three Cartesian directions: x (p < 0.01), y (p < 0.01), z (p < 0.01). In addition, the intensity values for three different heights are statistically significantly correlated using the RILZ coil system (p < 0.01). The differences in cell behaviour are also statistically significant between the two systems (p < 0.01) and may be directly related to the differences found in the distribution of intensity values between the two systems. This study highlights the importance of the homogeneity of the magnetic field intensity generated by the exposure systems used and offers an effective solution to control the magnetic field exposure parameters in vitro assays.

Promising application of pulsed electromagnetic fields on tissue repair and regeneration

Tissue repair and regeneration is a vital biological process in organisms, which is influenced by various internal mechanisms and microenvironments. Pulsed electromagnetic fields (PEMFs) are becoming a potential medical technology due to its advantages of effectiveness and non-invasiveness. Numerous studies have demonstrated that PEMFs can stimulate stem cell proliferation and differentiation, regulate inflammatory reactions, accelerate wound healing, which is of great significance for tissue regeneration and repair, providing a solid basis for enlarging its clinical application. However, some important issues such as optimal parameter system and potential deep mechanisms remain to be resolved due to PEMFs window effect and biological complexity. Thus, it is of great importance to comprehensively summarizing and analyzing the literature related to the biological effects of PEMFs in tissue regeneration and repair. This review expounded the biological effects of PEMFs on stem cells, inflammation response, wound healing and musculoskeletal disorders in order to improve the application value of PEMFs in medicine. It is believed that with the continuous exploration of biological effects of PEMFs, it will be applied increasingly widely to tissue repair and other diseases.

Molecular Biological Effects of Weak Low-Frequency Magnetic Fields: Frequency-Amplitude Efficiency Windows and Possible Mechanisms

This review covers the phenomenon of resonance-like responses of biological systems to low-frequency magnetic fields (LFMF). The historical development of this branch of magnetobiology, including the most notable biophysical models that explain the resonance-like responses of biological systems to LFMF with a specific frequency and amplitude, is given. Two groups can be distinguished among these models: one considers ion-cofactors of proteins as the primary targets for the LFMF influence, and the other regards the magnetic moments of particles in biomolecules. Attention is paid to the dependence of resonance-like LFMF effects on the cell type. A radical-pair mechanism of the magnetic field's influence on biochemical processes is described with the example of cryptochrome. Conditions for this mechanism's applicability to explain the biological effects of LFMF are given. A model of the influence of LFMF on radical pairs in biochemical oscillators, which can explain the frequency-amplitude efficiency windows of LFMF, is proposed.

Biological effects of rotating magnetic field: A review from 1969 to 2021

As one of the common variable magnetic fields, rotating magnetic field (RMF) plays a crucial role in modern human society. The biological effects of RMF have been studied for over half a century, and various results have been discovered. Several reports have shown that RMF can inhibit the growth of various types of cancer cells in vitro and in vivo and improve clinical symptoms of patients with advanced cancer. It can also affect endogenous opioid systems and rhythm in central nerve systems, promote nerve regeneration and regulate neural electrophysiological activity in the human brain. In addition, RMF can influence the growth and metabolic activity of some microorganisms, alter the properties of fermentation products, inhibit the growth of some harmful bacteria and increase the susceptibility of antibiotic-resistant bacteria to common antibiotics. Besides, there are other biological effects of RMF on blood, bone, prenatal exposure, enzyme activity, immune function, aging, parasite, endocrine, wound healing, and plants. These discoveries demonstrate that RMF have great application potential in health care, medical treatment, fermentation engineering, and even agriculture. However, in some cases like pregnancy, RMF exposure may need to be avoided. Finally, the specific mechanisms of RMF's biological effects remain unrevealed, despite various hypotheses and theories. It does not prevent us from using it for our good.

Theoretical Concepts in Magnetobiology after 40 Years of Research

This review contains information on the development of magnetic biology, one of the multidisciplinary areas of biophysics. The main historical facts are presented and the general observed properties of magnetobiological phenomena are listed. The unavoidable presence of nonspecific magnetobiological effects in the everyday life of a person and society is shown. Particular attention is paid to the formation of theoretical concepts in magnetobiology and the state of the art in this area of research. Some details are provided on the molecular mechanisms of the nonspecific action of a magnetic field on organisms. The prospects of magnetobiology for the near and distant future are discussed.

Random Effects in Magnetobiology and a Way to Summarize Them

In magnetobiology, it is difficult to reproduce the nonspecific (not associated with specialized receptors) biological effects of weak magnetic fields. This means that some important characteristic of the data may be missed in standard statistical processing, where the set of measurements to be averaged belongs to the same population so that the contribution of fluctuations decreases according to the Central Limit Theorem. It has been shown that a series of measurements of a nonspecific magnetic effect contains not only the usual scatter of data around the mean but also a significant random component in the mean itself. This random component indicates that measurements belong to different statistical populations, which requires special processing. This component, otherwise called heterogeneity, is an additional characteristic that is typically overlooked, and which reduces reproducibility. The current method for studying and summarizing highly heterogeneous data is the random-effect meta-analysis of absolute values, i.e., of magnitudes, rather than the values themselves. However, this estimator-the average of absolute values-has a significant positive bias when it comes to the small effects that are characteristic of magnetobiology. To solve this problem, an improved estimator based on the folded normal distribution that gives several times less bias is proposed. We used this improved estimator to analyze the nonspecific effect of the hypomagnetic field in the Stroop test in 40 subjects and found a statistically significant meta-effect with a standardized average of magnitudes of about 0.1. It has been shown that the proposed approach can also be applied to a single study. © 2021 Bioelectromagnetics Society.

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.

Risk to pollinators from anthropogenic electro-magnetic radiation (EMR): Evidence and knowledge gaps

Worldwide urbanisation and use of mobile and wireless technologies (5G, Internet of Things) is leading to the proliferation of anthropogenic electromagnetic radiation (EMR) and campaigning voices continue to call for the risk to human health and wildlife to be recognised. Pollinators provide many benefits to nature and humankind, but face multiple anthropogenic threats. Here, we assess whether artificial light at night (ALAN) and anthropogenic radiofrequency electromagnetic radiation (AREMR), such as used in wireless technologies (4G, 5G) or emitted from power lines, represent an additional and growing threat to pollinators. A lack of high quality scientific studies means that knowledge of the risk to pollinators from anthropogenic EMR is either inconclusive, unresolved, or only partly established. A handful of studies provide evidence that ALAN can alter pollinator communities, pollination and fruit set. Laboratory experiments provide some, albeit variable, evidence that the honey bee Apis mellifera and other invertebrates can detect EMR, potentially using it for orientation or navigation, but they do not provide evidence that AREMR affects insect behaviour in ecosystems. Scientifically robust evidence of AREMR impacts on abundance or diversity of pollinators (or other invertebrates) are limited to a single study reporting positive and negative effects depending on the pollinator group and geographical location. Therefore, whether anthropogenic EMR (ALAN or AREMR) poses a significant threat to insect pollinators and the benefits they provide to ecosystems and humanity remains to be established.

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.