Magnetoreception in laboratory mice: sensitivity to extremely low-frequency fields exceeds 33 nT at 30 Hz

Effects of the geomagnetic field time-varying components compensation as evidenced by heart rate variability of healthy males

Evolutionarily, a human organism is adapted to the natural geomagnetic environment and its slight alterations. However, during geomagnetic storms (GMSs), the strength of the geomagnetic field (GMF) sharply increased hundreds of times and can pose a serious threat to people. We examine the effects of controlled compensation in the time-varying components of the GMF, using a specially created experimental setup with electrically shielding solutions, providing an electromagnetically quiet environment. The measurement of heart rate variability (HRV) on 25 healthy young male volunteers was carried out in the laboratory using the experimental setup at different levels of outdoor geomagnetic activity (GMA). The geomagnetic K-index was used to characterize the magnitude of GMSs; volunteers were tested during quiet magnetic days (K = 1-3), days with K = 4, and days with GMSs (K ≥ 5) in the period of solar cycle maximum. During quiet magnetic days, the comparison between HRV baseline values with values measured under GMF time-varying components compensation mode (CM) did not reveal any changes. On days with K = 4 some HRV indices shifted from their initial values, but it was statistically not significant. However, on days with GMSs statistically significant changes in SDNN* (p = 0.033) and LF* (p = 0.011) indices of HRV were observed in the GMS CM compared to their baseline values. The experiments showed that GMSs cause a sensitive reaction of the heart rate regulatory mechanism, the effect of which can be canceled in the GMS CM. The efficiency of the used technology is supported by the results of this study. * SDNN (Standard Deviation Normal to Normal R-R of cardiointervals), LF (Low frequency spectral band of cardiointervals).

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.

Dosimetric analysis of hands exposure during handling of strong permanent magnets

Workers in a production line for synchronous motors occasionally reported tingling sensations or a feeling of numbness in their hands when handling strong permanent magnets. As the magnetic flux density (B) and its gradients along and close to the surface of the permanent magnets were expected to be comparably high and the movements of the workers' hands may therefore cause relevant induction inside the tissue, a detailed dosimetric analysis of the in situ electric field inside the hands (E_i) of the workers was carried out. The time derivate of the magnetic flux density (dB/dt) occurring along the hands was determined based on time domain measurements using a specially developed 'measurement glove' containing 12 Hall sensors. Based on these measurement results temporal peak electric field strength (E_i) induced inside a newly developed high resolution anatomical hand models were numerically computed, using the scalar potential finite difference (SPFD) method. The highest measured dB/dt along the palmar side of the hand was 51.2 T s^-1. The corresponding worst case temporal peak value of the maximum of the E_i averaged over 2 × 2 × 2 mm³ in soft tissue was 2.0 V m^-1, which is a factor of 1.8 higher than the applicable exposure limit value, but still below the range of 3.8-6.2 V m^-1 which is presently assumed the range of lowest stimulation threshold for peripheral nerves. Our analysis did therefore not provide an indication that the perception reported by the workers are due to tissue stimulation in the sense of provoking action potentials.

The associations of geomagnetic storms, fast solar wind, and stream interaction regions with cardiovascular characteristic in patients with acute coronary syndrome

It is shown the statistical associations between space weather pattern and humans' cardiovascular system. We investigated the association between space weather events and cardiovascular characteristics of 4076 randomly selected patients with acute coronary syndrome (ACS) who were admitted for inpatient treatment in Kaunas city, Lithuania during 2000-2005. We hypothesized that days of the space weather events, 1-3 days after, and the period between two events, named as intersection days (1-3 days after the event, which coincided with 1-3 days before the event), might be associated with patients' cardiovascular characteristics. The multivariate logistic regression was applied, and the patients' risk was evaluated by odds ratio (OR), adjusting for age, sex, smoking status, the day of the week, and seasonality. During the intersection days of geomagnetic storms (GS), the risk of ACS increases in obese patients (OR=1.72, p = 0.008). The risk of ventricular fibrillation during admission was associated with stream interaction region (SIR) with a lag of 0-3 days (OR=1.44, p = 0.049) The risk of ACS in patients with chronic atrial fibrillation was associated with fast solar wind (FSW) (≥600 km/s) (lag 0-3 days, OR=1.39, p = 0.030) and with days of solar proton event (lag 0-3) going in conjunction with SIR (lag 0-3) (OR=2.06, p = 0.021). During days which were not assigned as GS with a lag of (-3 to 3) days, FSW (lag 0-3) was associated with the risk of ACS in patients with renal disease (OR=1.71, p = 0.008) and days of SIR - with the risk in patients with pulmonary disease (OR=1.53, p = 0.021). A SIR event, days between two space weather events, and FSW without GS may be associated with a risk to human health.

Magnetocarcinogenesis: is there a mechanism for carcinogenic effects of weak magnetic fields?

Extremely low-frequency (ELF) magnetic fields have been classified as possibly carcinogenic, mainly based on rather consistent epidemiological findings suggesting a link between childhood leukaemia and 50-60 Hz magnetic fields from power lines. However, causality is not the only possible explanation for the epidemiological associations, as animal and in vitro experiments have provided only limited support for carcinogenic effects of ELF magnetic fields. Importantly, there is no generally accepted biophysical mechanism that could explain such effects. In this review, we discuss the possibility that carcinogenic effects are based on the radical pair mechanism (RPM), which seems to be involved in magnetoreception in birds and certain other animals, allowing navigation in the geomagnetic field. We review the current understanding of the RPM in magnetoreception, and discuss cryptochromes as the putative magnetosensitive molecules and their possible links to cancer-relevant biological processes. We then propose a hypothesis for explaining the link between ELF fields and childhood leukaemia, discuss the strengths and weaknesses of the current evidence, and make proposals for further research.

Reanalysis of an oft-cited paper on honeybee magnetoreception reveals random behavior

While mounting evidence indicates that a phylogenetically diverse group of animals detect Earth-strength magnetic fields, a magnetoreceptor has not been identified in any animal. One possible reason that identifying a magnetoreceptor has proven challenging is that, like many research fields, magnetoreception research lacks extensive independent replication. Independent replication is important because a subset of studies undoubtedly contain false positive results and without replication it is difficult to determine whether the outcome of an experiment is a false positive. However, we report here a reanalysis of a well-cited paper on honeybee magnetoreception demonstrating that the original paper represented a false positive finding caused by incorrect estimates of probability. We also point out how good experimental design practices could have revealed the error prior to publication. Hopefully, this reanalysis will serve as a reminder of the importance of good experimental design in order to reduce the likelihood of publishing false positive results.

Biological effects of the hypomagnetic field: An analytical review of experiments and theories

During interplanetary flights in the near future, a human organism will be exposed to prolonged periods of a hypomagnetic field that is 10,000 times weaker than that of Earth's. Attenuation of the geomagnetic field occurs in buildings with steel walls and in buildings with steel reinforcement. It cannot be ruled out also that a zero magnetic field might be interesting in biomedical studies and therapy. Further research in the area of hypomagnetic field effects, as shown in this article, is capable of shedding light on a fundamental problem in biophysics-the problem of primary magnetoreception. This review contains, currently, the most extensive bibliography on the biological effects of hypomagnetic field. This includes both a review of known experimental results and the putative mechanisms of magnetoreception and their explanatory power with respect to the hypomagnetic field effects. We show that the measured correlations of the HMF effect with HMF magnitude and inhomogeneity and type and duration of exposure are statistically absent. This suggests that there is no general biophysical MF target similar for different organisms. This also suggests that magnetoreception is not necessarily associated with evolutionary developed specific magnetoreceptors in migrating animals and magnetotactic bacteria. Independently, there is nonspecific magnetoreception that is common for all organisms, manifests itself in very different biological observables as mostly random reactions, and is a result of MF interaction with magnetic moments at a physical level-moments that are present everywhere in macromolecules and proteins and can sometimes transfer the magnetic signal at the level of downstream biochemical events. The corresponding universal mechanism of magnetoreception that has been given further theoretical analysis allows one to determine the parameters of magnetic moments involved in magnetoreception-their gyromagnetic ratio and thermal relaxation time-and so to better understand the nature of MF targets in organisms.

The magnetic orientation of the Antarctic amphipod Gondogeneia antarctica is cancelled by very weak radiofrequency fields

Studies on weak man-made radiofrequency electromagnetic fields (RF) affecting animal magnetoreception aim for a better understanding of the reception mechanism and also point to a new phenomenon having possible consequences in ecology and environmental protection. RF impacts on magnetic compasses have recently been demonstrated on migratory birds and other vertebrates. We set out to investigate the effect of RF on the magnetic orientation of the Antarctic krill species Gondogeneia antarctica, a small marine crustacean widespread along the Antarctic littoral line. Here, we show that having been released under laboratory conditions, G. antarctica escaped in the magnetically seaward direction along the magnetic sea-land axis (Y-axis) of the home beach. However, the animals were disoriented after being exposed to RF. Orientation was lost not only in an RF of a magnetic flux density of 20 nT, as expected according to the literary data, but even under the 2 nT originally intended as a control. Our results extend recent findings of the extraordinary sensitivity of animal magnetoreception to weak RF fields in marine invertebrates.

The Effect of Extremely Low Frequency Alternating Magnetic Field on the Behavior of Animals in the Presence of the Geomagnetic Field

It is known that the geomagnetic field can influence animal migration and homing. The magnetic field detection by animals is known as magnetoreception and it is possible due to two different transduction mechanisms: the first one through magnetic nanoparticles able to respond to the geomagnetic field and the second one through chemical reactions influenced by magnetic fields. Another behavior is the magnetic alignment where animals align their bodies to the geomagnetic field. It has been observed that magnetic alignment of cattle can be disrupted near electric power lines around the world. Experimentally, it is known that alternating magnetic fields can influence living beings, but the exact mechanism is unknown. The parametric resonance model proposes a mechanism to explain that effect on living beings and establishes that, in the presence of a constant magnetic field, molecules associated with biochemical reactions inside cells can absorb resonantly alternating magnetic fields with specific frequencies. In the present paper, a review is made about animal magnetoreception and the effects of alternating magnetic fields in living beings. It is suggested how alternating magnetic fields can interfere in the magnetic alignment of animals and a general conclusion is obtained: alternating magnetic field pollution can affect the magnetic sensibility of animals.

The effects of weak magnetic fields on radical pairs

It is proposed that radical concentrations can be modified by combinations of weak, steady and alternating magnetic fields that modify the population distribution of the nuclear and electronic spin state, the energy levels and the alignment of the magnetic moments of the components of the radical pairs. In low external magnetic fields, the electronic and nuclear angular momentum vectors are coupled by internal forces that outweigh the external fields' interactions and are characterized in the Hamiltonian by the total quantum number F. Radical pairs form with their unpaired electrons in singlet (S) or triplet (T) states with respect to each other. At frequencies corresponding to the energy separation between the various states in the external magnetic fields, transitions can occur that change the populations of both electron and nuclear states. In addition, the coupling between the nuclei, nuclei and electrons, and Zeeman shifts in the electron and nuclear energy levels can lead to transitions with resonances spanning frequencies from a few Hertz into the megahertz region. For nuclear energy levels with narrow absorption line widths, this can lead to amplitude and frequency windows. Changes in the pair recombination rates can change radical concentrations and modify biological processes. The overall conclusion is that the application of magnetic fields at frequencies ranging from a few Hertz to microwaves at the absorption frequencies observed in electron and nuclear resonance spectroscopy for radicals can lead to changes in free radical concentrations and have the potential to lead to biologically significant changes.