ABSTRACT This study aimed to examine the impacts of extremely low-frequency (ELF)-electromagnetic field (EMF) on cognitive functions and analgesia in terms of total oxidant status (TOS) and total antioxidant status (TAS) in the experimental pentylenetetrazole (PTZ)-induced epilepsy model. Twenty-four Wistar albino male rats were categorized into four groups: sham, EMF, PTZ, and EMF+PTZ. The rats were repeatedly exposed to alternating 50-Hz and 5-mT EMF for 165 min a day for 7 days. Epileptic seizures were induced with PTZ. The levels of oxidative stress markers were measured. Univariate multifactorial one-way analysis of variance and post hoc Tukey’s test were used for pairwise comparisons between groups. A statistically significant difference was observed in the learning and short-term memory levels in the EMF + PTZ group compared with the PTZ group (p < 0.001). Analgesia latency statistically significantly increased in the ELF-EMF and ELF-EMF+PTZ groups compared with both the control and epilepsy groups (p < 0.001). A statistically significant increase in TOS was found in the prefrontal cortex in the PTZ group compared with the sham group (p < 0.001). Also, TOS statistically significantly increased in the hippocampus in both PTZ and ELF-EMF+ PTZ groups compared with the sham group (p < 0.001). ELF-EMF decreased the increased TOS in the hippocampus of rats in the PTZ group.

ABSTRACTMeta‐analyses of epidemiological studies have suggested that Alzheimer's disease (AD) may be linked with exposure to extremely low frequency (ELF) magnetic fields (MF). This is the first study investigating the association of AD with exposure to residential ELF MFs from indoor transformer stations, using a study design that avoids shortcomings of previous studies. All cohort members had lived in buildings with indoor transformer stations. MF exposure was assessed based on the location of their apartment in relation to the transformer room. AD patients were identified from Drug Purchase Register and Drug Reimbursement Register. Out of the 155,562 individuals, 5652 (111,357 person‐years of follow‐up) living in apartments next to transformer stations were considered as exposed, while 115,772 (2,289,526 person‐years of follow‐up) individuals living on higher floors of the same buildings were considered as referents. Associations between MF exposure and AD were examined using Cox proportional hazard models. The hazard ratio (HR) was 1.02 (95% confidence interval: 0.85–1.22), indicating that the risk of AD is not associated with residential ELF MFs present in apartments next to transformer stations. The duration of residence did not essentially change the HR. The risk of AD was slightly but not statistically significantly higher (HR 1.22, 95% confidence interval: 0.94–1.57) for those whose residence started before the age of 50 years. The results did not support positive findings from previous studies that have reported a link between AD and occupational or residential MF exposure. Bioelectromagnetics. 00:00–00, 2025.

Out-of-equilibrium Rydberg gases exhibit emergent many-body phases due to mode competition. Sustained limit cycle oscillations (OSC) emerge when driven by B-fields at room temperature, forming robust Rydberg dissipative time crystals (DTC). Here we show that DC and AC Stark fields in the sub-kHz regime can be used to precisely shift (DC) or modulate (AC) the oscillation frequency of these DTCs, providing a powerful method for controllable time-domain dynamics in a room-temperature system. The AC Stark modulation induces frequency modulation (FM) of the OSC spectrum, enabling narrowband detection of extremely weak AC electric fields in the sub-kHz regime, with DC fields detected via Stark-induced shifts of the oscillation frequency. With a modest setup, a sensitivity of ~ 7.8µVcm- 1Hz- 1/2 at 300Hz is demonstrated - an ~ 8.7× improvement over state-of-art in the sub-kHz regime. Unlike on-resonant DTC sensing that is limited to operation close to the emergent limit cycle oscillations (10-15kHz), the present approach is effective in the DC-600Hz sub-kHz regime. This approach overcomes the size and bandwidth limitations of classical antennas at ultra-low frequencies and establishes a new class of ultra-compact (≪λ/10⁶) Rydberg-based electric-field sensors. These results open opportunities for compact extremely low-frequency (ELF) sensors in remote sensing, communications, geophysics, and biomedical diagnostics.

Extremely Low Frequency (ELF) electric field signal provides a novel and promising solution to the target location problem due to its strong resistance to jamming and long propagation range. However, conventional algorithms such as Multiple Signal Classification (MUSIC) often rely heavily on accurate prior information. In this paper, we propose a novel underwater electric field location algorithm to accurately locate an unknown number of targets. This paper constructs a complete output model of electric field detection array in the spatial domain based on Sparse Bayesian Learning (SBL), and transforms the target location problem into sparse signal reconstruction problem. The experimental results demonstrate the effectiveness of the proposed method and its advantages over the MUSIC algorithm. The proposed location algorithm is capable of accurately locating an unknown number of ships and other targets.

Electromagnetic radiation (EMR), spanning a vast spectrum from extremely low-frequency (ELF) waves to highly energetic ionizing forms such as X-rays and gamma rays, has become increasingly pervasive in today’s world. The rapid advancement and widespread use of wireless communication systems, electrical appliances, and medical imaging technologies have amplified human exposure to EMR. This review examines how such exposure impacts human biology and health, emphasizing the differences between ionizing and non-ionizing radiation. Non-ionizing radiation—originating from devices like mobile phones, Wi-Fi routers, and microwave transmitters—has been linked to potential thermal and non-thermal biological changes, including oxidative stress, altered cellular function, and neurological symptoms. In contrast, ionizing radiation is well known for its ability to cause DNA damage, mutations, and cancer. Although international safety limits has been established based on existing evidence, emerging research points toward a need for revising these standards, especially concerning prolonged low-level exposure to non-ionizing radiation. This paper summarizes current findings, identifies knowledge gaps, and underscores the necessity of sustained multidisciplinary research to better understand long-term EMR health implications.

Glioblastoma multiforme (GBM) is a highly aggressive astrocytic glioma with a devastating survival rate of less than 7%. Despite treatment with surgical resection and chemoradiotherapy, a majority of GBM cases recur. The intricate tumor microenvironment and the elusive nature of its recurrence are still controversial. Herein, we explore the role of neuronal hyperstimulation in glioblastoma cell regrowth post-chemotherapy, focusing on cancer-neuron interactions. A direct electrical stimulation system, validated by COMSOL Multiphysics simulation, was used to induce stimulation of neuronal networks through the formation of an extremely low frequency (ELF) electric field, and changes by excitability were tracked. The custom-designed co-culture system, enabling the sharing of paracrine signals in an independent microenvironment cultivation of neuronal networks and glioblastoma cell, was employed to investigate the effects of neuronal excitability on glioblastoma cell. Power-frequency electric fields are applied to hippocampal neuronal networks to elicit abnormal neuronal activity, evidenced by calcium influx and neurotransmitter release. While temozolomide effectively suppresses glioblastoma cell proliferation, their co-culture with stimulated neurons reignites cancer growth. Blocking glutamate release from neuron networks counter the effects of neuronal activity, highlighting the significance of paracrine signaling in glioblastoma cell proliferation and recurrence. Our findings illuminate a pathway through which environmental factors contribute to GBM regrowth following chemotherapy and propose a potential therapeutic target, neuron-cancer communication, to prevent GBM recurrence.

Carcinogenicity of extremely low-frequency magnetic fields: A systematic review of animal studies.

The Absolute Scalar Magnetometers (ASM) onboard each European Space Agency Swarm satellites nominally provide 1 Hz magnetic scalar data. An additional experimental mode is available on the ASM consisting of a 250 Hz burst-mode which is periodically switched on allowing magnetic signals with frequencies up to 125 Hz to be investigated. By analysing burst-mode data from 2014 to 2023 in the frequency-time domain, we find a range of signals both man-made and geophysical, which we present here. Known features include lightning whistlers, auroral hiss and plasma bubbles that produce broadband incoherent signatures, and powerline harmonic radiation observed as stable 50 or 60 Hz lines. Ground based extremely low frequency (ELF) communication systems are also detected in the data. However, many as yet unexplained signals are observed. Rising-tone 70-125 Hz high-intensity bursts, lasting ~3 minutes, are found over the Antarctic, which we suggest are associated with local He+ ion gyrofrequencies and thus are possibly narrow-banded ionospheric hiss. These signals appear to be associated with the South Atlantic Anomaly due to their clustering on its southern edge, with the low field strength producing He+ gyrofrequencies less than 125~Hz. Additionally, extremely weak linear and quadratic chirps lasting tens of seconds to tens of minutes occur in the data without an obvious temporal or spatial trend which we tentatively attribute to onboard electronic or instrumental noise. Their origin requires further investigation to avoid artefacts in future magnetic missions. We also find long lasting, high frequency narrow-band features around 80-125~Hz which persist for 60-300 seconds, occurring orbit-on-orbit at fixed magnetic local times (MLT) around 0900 and 1500, mainly in equatorial latitudes, which are encountered during all burst sessions spanning these MLTs. The Swarm ASM burst-mode data suggest there are new geophysical magnetic phenomena yet to be fully understood, potentially offering new insights into magnetospheric and ionospheric wave-plasma interactions.

Exposure to anthropogenic electromagnetic fields (EMFs), especially those of wireless communications (WC) has increased tremendously. This is an unprecedented phenomenon throughout biological evolution because, all anthropogenic EMFs, being fully polarized, coherent, and, especially WC EMFs, highly variable, differ substantially from the natural EMFs. WC EMFs consist of Microwave (MW) carrier waves, modulated, by Extremely Low Frequency (ELF) signals, and included in on/off pulses repeated at various ELF rates. Moreover, they exhibit intense random variability, mainly in the Ultra Low Frequency (ULF) band. Thus, WC EMFs are a combination of MW and ELF/ULF EMFs. The combination of polarization/coherence and intense low-frequency (ELF/ULF) variability seems to be the key to EMF-bioactivity. Epidemiological and laboratory studies highlight a connection between ELF or WC EMF exposure and cancer, infertility, electro-hypersensitivity, and various other pathologies. Studies also find DNA damage and Oxidative Stress (OS) which explain these pathologies. While man-made EMFs cannot directly ionize molecules, they are capable of doing this indirectly in biological tissue, by triggering the biosynthesis of Reactive Oxygen Species (ROS) which can damage biomolecules, including DNA. The (over)production of ROS and the consequent OS are triggered by irregular gating of Voltage-Gated Ion Channels (VGICs) in the cell membranes as described by the Ion Forced Oscillation (IFO)-VGIC mechanism: Mobile ions within VGICs forced to oscillate by the applied ELF/ULF EMFs exert forces on the voltage sensors of the VGICs, similar to or greater than the forces that physiologically gate those channels, resulting in their irregular gating (dysfunction). Dysfunction of ion channels disrupts intracellular ionic concentrations. This triggers ROS overproduction and OS by the ROS-generating systems/enzymes in the cells, such as the electron transport chain (ETC) in the mitochondria, or the NADPH/NADH oxidases (NOXs), the Nitric Oxide synthases (NOS), etc. The IFO-VGIC mechanism and the consequent OS constitute a comprehensive mechanism that explains all known adverse biological and health effects reported to be induced by anthropogenic EMFs.

Using Schumann resonance (SR) records from the Antarctic, we evaluate the impact of the solar activity on the global ionosphere over the period from 2002 to 2024. The updated vertical profile of the middle atmosphere conductivity is applied. The pivoted upper part of profiles above the knee altitude is adjusted to represent different levels of solar activity. The electric (lower) hC and the magnetic (upper) hL characteristic heights, the propagation constant ν(f) of the extremely low frequency (ELF) radio waves, and the basic resonance frequency f1 are computed for the profiles corresponding to the solar maximum, moderate, and minimum activity conditions by using the full-wave solution in the form of the Riccati differential equation. Model data are compared with experimental observations at the Ukrainian Antarctic Station of “Akademik Vernadsky” (geographic coordinates: 65.25° S and 64.25° W). The following results are discussed: (i) Solar activity modifies the upper characteristic height hL of the ionosphere by ±1 km over the 11-year cycle; (ii) Equations were obtained linking the current level of solar activity with the basic SR frequency, with the magnetic characteristic height, and with the ELF propagation constant; (iii) Based on SR monitoring within two complete solar cycles, a practical rule is proposed: an increase in the index of solar activity I10.7 by ~150 units raises the first SR frequency by ~0.1 Hz and elevates the magnetic characteristic height by ~2.5 km.

The use of electrical appliances using extremely low frequency (ELF) electromagnetic fields (EMF) has increased in the past few years. These ELF MF are reported to be linked to several adverse health effects. However, only a couple of studies have been conducted on the association between risk of tumours and use of electronic devices using low frequency (LF) EMF. We studied the use of common household electrical appliances and suspected risk of tumours in a multi-hospital-based case-control study. In total, 316 patients were included in the final analysis. The study results showed a below unity risk for most of the devices. A slight increased risk of tumour was observed for computer screen use OR: 1.13 (95% CI: 0.43-3.02) and use of microwave oven OR: 1.21 (95% CI: 0.36-4.04). We also had chance to investigate ELF MFs exposure association with tumour. Where we observed elevated odd ratios in individuals living near electricity transformer stations, with a statistically significant risk OR: 2.16 (95% CI: 1.30-3.59). However, the risk was below unity (OR: 0.98) in individuals residing close to powerlines. The current study serves as a pilot study of primary data and will be helpful in future epidemiological research studies on the topic in the region.

Environmental risk factors for all-cause dementia, Alzheimer's disease dementia, vascular dementia, and mild cognitive impairment: An umbrella review and meta-analysis.

This study aims to evaluate the effect of Extremely Low Frequency (ELF) magnetic field exposure on chlorophyll content in aged rice (Oryza sativa L.) seeds during the vegetative phase. Chlorophyll is the primary pigment in photosynthesis, playing a crucial role in light absorption and the conversion of energy into organic matter essential for plant growth. The research method used was a completely randomized design (CRD) with ELF magnetic field exposure treatments at an intensity of 0.2 mT for 3 minutes 54 seconds, 7 minutes 48 seconds, 11 minutes 42 seconds, and a control treatment without exposure. The results showed that (1) ELF magnetic field exposure for 11 minutes 42 seconds produced the highest chlorophyll a, chlorophyll b, and total chlorophyll content compared to other treatments. (2) The control treatment (P0) resulted in lower chlorophyll a, chlorophyll b, and total chlorophyll content than the P1, P2, and P3 treatments. (3) Longer exposure durations, such as in the P3 treatment, were proven to significantly increase chlorophyll content, potentially optimizing the photosynthesis process in rice plants.

The deterioration in the viability of rice seeds (Oryza sativa L.) during storage, frequently attributed to damage to the cell membrane and accumulation of reactive oxygen species (ROS), presents significant challenges for rice cultivation. ELF magnetic fields offer an eco-friendly solution by enhancing cellular responses and repairing membranes. This study investigated the impact of exposure to a 0.2 mT ELF magnetic field on the viability of 8-month-old aged rice seeds (Inpari 32 HDB variety) using a Completely Randomized Design (CRD) with four exposure durations: control (M0), 3 minutes 54 seconds (M1), 7 minutes 48 seconds (M2), and 11 minutes 42 seconds (M3), replicated four times. Results indicated significant improvements in viability, with M2 and M3 yielding optimal germination rates (98.00%, 97.50%), reduced mean germination time (2.47 days), and enhanced germination index (268.75). Radicle and plumule lengths also increased (6.95 cm and 4.82 cm, respectively). Although germination speed coefficient, germination time, and uniformity values (51.50–60.50%) showed only minor improvements, the results underscore the potential of ELF magnetic fields as a sustainable method to enhance aged rice seed viability, contributing to improved agricultural practices.

Abstract Through the emission of high‐frequency radio waves, ground‐based heating facilities can generate Extremely‐Low‐Frequency (ELF) and Very‐Low‐Frequency (VLF) waves in the ionosphere, a portion of which can penetrate into the Earth's radiation belts and influence the electron population therein. Although various measurements of ELF/VLF waves generated by ionospheric heating experiments have been reported, combined analysis using both observations and simulations remain quite limited and, thus, the underlying effects of these experiments are not well understood. In this study, we quantify these effects using measurements of plasma waves and high‐energy electrons during the joint experiment conducted between the China Seismo‐Electromagnetic Satellite (CSES) and the ionospheric heater SURA on 17 November 2021. We show that SURA‐generated ELF/VLF waves are mostly in the frequency range of 1–5 kHz as measured by CSES, with an amplitude of ∼50 pT at 0.8–2 kHz. The overall structure is similar to previous measurements of ELF/VLF waves generated by the High‐Frequency Active Auroral Research Program (HAARP). These waves can, in principle, influence electrons in the 100–250 keV energy range, mostly via pitch‐angle diffusion. On basis of further simulations of the evolution of electron phase space density under the impact of SURA‐generated ELF/VLF waves, our modeling output shows favorable consistency with the electron flux variations measured by CSES. Our results support a causative relation between the SURA heating experiment and the CSES‐observed dynamics of ELF/VLF waves and energetic electrons, which has important implications to further our understanding of the near‐Earth space environment and to develop artificial radiation belt remediation techniques.

Abstract The interaction of very low frequency (VLF) and extremely low frequency (ELF) electromagnetic waves with nanocomposites is rarely explored. It is demonstrated that low‐dimensional electrically conducting fillers are able to shield extremely long wavelengths, provided they form extended conduction paths through percolation. Other mechanisms that synergistically augment the shielding of the high frequencies, such as skin effect, interfacial polarization, and multiple internal scattering, have insignificant effects in the low‐frequency range. In this regard, high aspect ratio 1D conductors having the lowest percolation thresholds provide the best shielding performance, both gravimetrically and volumetrically. Shielding in these materials are observed majorly occur mostly through reflection, and hence, these materials can be employed for both shielding and guiding low frequencies. The correlation proposed to estimate shielding effectiveness based on conductivity and frequency enables convenient material design for low‐frequency modulation.

Mechanical antennae have been considered a promising solution for the miniaturization of underwater low-frequency communication. The research on mechanical antennae mainly focuses on the use of strong magnetic fields rather than strong electric fields at present. This paper proposed a method to generate extremely low-frequency (ELF) electromagnetic waves by utilizing the periodic motion of conductive spheres to disturb a strong electrostatic field. Both theoretical analysis and experimental verification demonstrated that this method can effectively generate ELF electromagnetic waves matching the frequency of the conductive spheres. A mechanical antenna system was designed and fabricated combining a sphere-string structure next to a van de Graaff generator, based on the above principle. Leveraging the multi-modal rapid frequency-switching characteristics of the sphere-string structure, an effective information-loading method was proposed and realized for ELF communication. This study provides more options for the radiator and information modulation of mechanical antennae.

Abstract The Extremely Low Frequency band (ELF: 0.03–1,000 Hz) electromagnetic signals from thunderstorm lightning discharges can propagate around the globe in the Earth‐ionosphere resonance cavity and thus be used for ionosphere monitoring. We use ELF observations of impulses detected by the World Wide Lightning Location Network (WWLLN) to investigate ELF propagation velocity and arrival azimuth under diurnal changes over 2 days in September 2023. Also, temporary effects of solar flares' ionizing fluxes are monitored, leading to increase of the ELF signal propagation speed in proportion to the X‐ray flux intensity. We present a simple method for automatic and large‐scale analysis, utilizing data from two registration systems (our ELF reciever and WWLLN) and enabling easy evaluation of changes in wave propagation speed. Comparative analysis of WWLLN identified impulses generated in Africa and America reveals varying effects of signal refraction, with increased azimuth changes for signals propagating across the ionospheric ionization gradients associated with the day/night terminator. The method has a potential to become a standard tool for the analysis and monitoring of the lower layers of the ionosphere.

Abstract The finite‐difference time‐domain (FDTD) method was previously applied to high‐frequency electromagnetic wave propagation through 250 km of the F region of the ionosphere. That modeling approach was limited to electromagnetic wave propagation above the critical frequency of the ionospheric plasma, and it did not include the lower ionosphere layers or the top of the F‐region. This paper extends the previous modeling methodology to frequencies below the critical frequency of the plasma and to altitudes encompassing the ionosphere. The following changes to the previous work were required to generate this model: (a) the D, E and top of the F regions of the ionosphere were added; and (b) the perfectly matched layer absorbing boundary on the top side of the grid was replaced with a collisional plasma to prevent reflections. We apply this model to the study of extremely low frequency (ELF) and very low frequency (VLF) electric power line harmonic radiation (PLHR) through the ionosphere. The model is compared against analytical predictions and applied to PLHR propagation in polar, mid‐latitude and equatorial regions. Also, to further demonstrate the advantages of the grid‐based FDTD method, PLHR propagation through a polar cap patch with inhomogeneities is studied. The presented modeling methodology may be applied to additional scenarios in a straightforward manner and can serve as a useful tool for better tracking and studying electromagnetic wave propagation through the ionosphere at any latitude and in the presence of irregularities of any size and shape.

Abstract To address the limitations of traditional wellbore communication technologies and address the shortcomings in synchronization and channel analysis of electromagnetic waves wellbore communication models, this paper proposes a novel wellbore wireless communication method using Extremely Low Frequency (ELF) electromagnetic waves. A polygonal multiple-delay complex network model for ELF electromagnetic waves propagation in wellbore and strata was established, which was divided into four subnetworks using network splitting theory: the oil tubing subnetwork, the casing subnetwork, the cement subnetwork, and the strata subnetwork. A controller was designed, successfully validating the stability of the model and achieving fast synchronization. The optimal transmitting frequency range was determined to be between 5 and 20Hz through theoretical derivation of attenuation factors and skin depth, combined with finite element simulations. Simulation results indicate that cement and casing are the primary transmission channels, followed by oil tubing and strata, with electric signals exhibiting significantly higher intensity than magnetic signals. Unlike electric signals, magnetic signals are less affected by shielding effects. Two field experiments confirmed the feasibility of using ELF electromagnetic waves for wellbore wireless communication, which can achieve a wireless communication distance of over 1600 meters without relays. This research provides a critical theoretical foundation and experimental validation for the future development of efficient wellbore wireless communication and intelligent wells.