Thursday, October 18, 2018

EMF in biology & medicine: International Journal Radiation Biology

 Special Issue: Electromagnetic fields in biology and medicine (Editorial)

Hinrikus H, Karpowicz J, Naarala J. Special Issue: Electromagnetic fields in biology and medicine. International Journal of Radiation Biology. 2018 Oct;94(10):873-876. doi: 10.1080/09553002.2018.1533359.
No abstract.


This Special Issue presents the papers reporting further development of ideas delivered and discussed in the special session ‘Electromagnetic fields in biology and medicine’ during the joint conference of the 7th European Medical and Biological Engineering Conference (EMBEC7) and the 17th Nordic-Baltic Conference on Biomedical Engineering and Medical Physics (NBC17), held in Tampere, Finland, June 2017. The focus on the state-of-the-art presentations on non-thermal mechanism(s) and biological responses to electromagnetic field (EMF) exposure has been underlined in the call for papers of the EMF special session. Three sub-sessions provided an international forum for presenting and discussing the latest developments in EMF biological and health effects as well as EMF applications in medicine....

Based on the results of scientific investigations, the International Agency for Research on Cancer has classified extremely low-frequency magnetic field as a possible human carcinogen in 2001 (IARC 2002 IARC. 2002. International Agency for Research on Cancer. 2002. Non-ionizing radiation, part 1: static and extremely low-frequency (ELF) electric and magnetic fields. Monographs on the evaluation of carcinogenic risks to humans, No 80. Geneva: WHO Press. [Google Scholar]) and radiofrequency EMF in 2011 (IARC 2013 IARC. 2013. International Agency for Research on Cancer. 2013. Non-ionizing radiation, part II: Radiofrequency electromagnetic fields. Monographs on the evaluation of carcinogenic risks to humans, No 102. Geneva: WHO Press. [Google Scholar]). Recently, the US National Toxicology Program Carcinogenesis Studies of Cell Phone Radiofrequency Radiation has published the results indicating increased cancer risk in rats (NTP 2018 NTP. 2018. NTP Technical report on the toxicology and carcinogenesis studies in Hsd:Sprague Dawley SD rats exposed to whole-body radio frequency radiation at a frequency (900 MHz) and modulations (GSM and CDMA) used by cell phones

... the findings reported in several studies in humans and animals (cellular stress, increase in free radicals, changes in DNA, functional changes in the reproductive system, alterations in the brain bioelectrical activity, learning and memory deficits etc.) at the levels of exposure below the thermal limits as well as several epidemiologic studies suggest the occurrence of EMF biological effects and the possibility of health effect at the levels of EMF exposure less than the set by the ICNIRP reference levels....

... the Parliamentary Assembly Council of Europe in its Resolution 1815 from 2011 recommends ‘reconsider the scientific basis for the present electromagnetic fields exposure standards set by the International Commission on Non-Ionising Radiation Protection, which have serious limitations and apply “as low as reasonably achievable” (ALARA) principles, covering both thermal effects and the athermic or biological effects of electromagnetic emissions or radiation’ (Parliamentary Assembly 2011 Parliamentary Assembly. 2011. Council of Europe, Resolution 1815. The potential dangers of electromagnetic fields and their effect on the environment. [Google Scholar]). However, only few European countries and cities have followed the recommendation....

The main topics selected for the Special Issue cover some of important aspects of the area: physical and biological mechanisms of radiofrequency radiation effects by Hinrikus et al. and Herrala et al.; response to microwave radiation in physiological systems by Selmanoui et al. and Bachmann et al.; reproductive effects of intermediate frequency magnetic field by Khan et al.; low-frequency magnetic field effect on immune response by Wyszkowska et al. Special attention has been paid to medical applications of EMF including safety problems for implants in two papers by Zradzinski et al.; connectivity between surface and deep bioelectric fields in brain by Jäntti et al.; and practical use of EMF for toxicity assessment of biological suspensions by Muñoz et al....

The ongoing discussions about 5G technology are based on a presumption that, due to very thin skin-layer, the EMF effect occurs only in human skin. However, in the case of real living systems, the processes in different tissues are interconnected. Therefore, excited by EMF skin structures are physiologically connected to deeper systems in body and the affected space can be much deeper....

Threshold of low-level EMF effects

All experimental studies published in the Special Issue have been performed at the EMF levels lower than the reference levels for general public set by the ICNIRP. An only exception is the SAR value of 6 W/kg used as the higher level of exposure in the study by Herrala et al.

The ICNIRP Guidelines are based on thermal interaction mechanism for the RF EMF effects. Therefore, the rise of temperature inside tissue is the only criterion for the possibility of an EMF effect. The specific absorption rate (SAR) is a relevant parameter to describe the intensity of exposure in the case of thermal mechanism. The SAR value, corresponding to the fixed level of induced by EMF increase of temperature, can be considered as the threshold of the EMF effect induced by the thermal interaction mechanism.

In the case of non-thermal interaction mechanisms, the absorbed energy has no more direct linear relationship with the effect. Therefore, SAR becomes irrelevant as a parameter describing the threshold of the EMF effects. Parallel to SAR, the ICNIRP has set the reference levels for electric and magnetic fields strengths and EMF power spectral density, more relevant in the case of nom-thermal interaction mechanisms. Do the reference levels for EM field strengths set by ICNIRP determine the threshold of the non-thermal mechanism of EMF effects?

Rotations of dipolar molecules and radical pairs are known to be evident at the EMF strengths much less than the thermal threshold. The dielectric constant is assumed being constant, therefore, no threshold for dielectric polarization of a medium is expected at low-level exposure. The rotation of dipolar molecules can occur at very weak EMF. Radical pairs are known being sensitive to very weak magnetic fields, for example in birds. In the case of the rotation of dipolar molecules or radical pairs, the physical restrictions determining the minimal field strengths sufficient for the rotation are still unknown.

The threshold of the non-thermal mechanisms of EMF effects needs further theoretical and experimental investigations keeping in mind that the additional affecting factors can influence the threshold of low-level EMF. The oscillating nature of several biological structures, first of all, heart cells and neurons, makes possible parametric excitation of biological oscillations even by very weak periodic external EMF. The impact of parametric excitation depends not only on the strength of periodic force but rather more on the duration of excitation. Chaotic nature of biological systems creates a possibility that a very small initial change in a parameter of the system can cause remarkable alterations of the ongoing processes and finally results in a significant change in the status of the system. Due to diversity of living systems, the sensitivity to low-level EMF is expected to be different for individuals.

Special Issue Papers

Understanding physical mechanism of low-level microwave radiation effect

Hinrikus H, Bachmann M, Lass J. Understanding physical mechanism of low-level microwave radiation effect. Int J Radiat Biol. 2018 Oct;94(10):877-882. doi: 10.1080/09553002.2018.1478158. Epub 2018 Jun 8.


PURPOSE:This topic review aims to explain the mechanism of low-level microwave (MW) radiation effect based on published research results. The review presents the analysis of theoretical and experimental results comprising underlying physics and derived biological-physiological consequences supported by experimental data.

CONCLUSIONS: The rotation of dipolar molecules causes polarization of dielectric medium and restructuring of hydrogen bonds between these molecules. The weakened hydrogen bonds decrease viscosity and enhance diffusion at constant temperature. All steps of proposed model have no critical frequency restrictions at MW frequencies and have been confirmed by electromagnetic field (EMF) theory and/or published experimental results. The synchronous cumulative impact of coherent MW electric field makes possible the field-induced effect despite the field strengths are much weaker than intermolecular fields. The rotation of dipolar molecules results in restructuring hydrogen bonds between the molecules despite the energy of MW radiation is much less than the energy of bonding. The cumulative impact of coherent MW field in a medium has been convincingly confirmed by the measurable dielectric permittivity of the medium. The described mechanism of MW field-induced effect confirms that the nature of the effect differs from the thermal effect and that the exposure by MW radiation can create the specific consequences in biology and materials not characteristic for conventional heating.

Assessment of genotoxicity and genomic instability in rat primary astrocytes exposed to 872 MHz radiofrequency radiation and chemicals

Herrala M, Mustafa E, Naarala J, Juutilainen J. Assessment of genotoxicity and genomic instability in rat primary astrocytes exposed to 872 MHz radiofrequency radiation and chemicals. Int J Radiat Biol. 2018 Oct;94(10):883-889. doi: 10.1080/09553002.2018.1450534. Epub 2018 Mar 23.


PURPOSE: We examined genotoxicity, co-genotoxicity and induced genomic instability (IGI) in primary astrocytes exposed to radiofrequency (RF) radiation.

MATERIALS AND METHODS: Rat primary astrocytes were exposed to 872 MHz GSM-modulated or continuous wave (CW) RF radiation at specific absorption rates of 0.6 or 6.0 W/kg for 24 h. Menadione (MQ) and methyl methanesulfonate (MMS; only in genotoxicity experiments) were used as co-exposures. Alkaline Comet assay and flow cytometric micronucleus scoring were used to detect genetic damage.

RESULTS: No IGI was observed from RF radiation alone or combined treatment with MQ. RF radiation alone was not genotoxic. RF radiation combined with chemical exposure showed some statistically significant differences: increased DNA damage at 6.0 W/kg but decreased DNA damage at 0.6 W/kg in cells exposed to GSM-modulated RF radiation and MQ, and increased micronucleus frequency in cells exposed to CW RF radiation at 0.6 W/kg and MMS.

CONCLUSIONS: Exposure to GSM modulated RF radiation at levels up to 6.0 W/kg did not induce or enhance genomic instability in rat primary astrocytes. Lack of genotoxicity from RF radiation alone was convincingly shown in multiple experiments. Co-genotoxicity of RF radiation and genotoxic chemicals was not consistently supported by the results.


After-effect induced by microwave radiation in human electroencephalographic signal: a feasibility study

Bachmann M, Päeske L, Ioannides AA, Lass J, Hinrikus H. After-effect induced by microwave radiation in human electroencephalographic signal: a feasibility study. Int J Radiat Biol. 2018 Oct;94(10):896-901. doi: 10.1080/09553002.2018.1478164. Epub 2018 Jun 20.


PURPOSE: This feasibility study is aimed to clarify the possibility of detection of microwave radiation (MWR)-induced event related potential (ERP) in electroencephalographic (EEG) signal.

METHODS: To trigger onset and offset effects in EEG, repetitive MWR stimuli were used. Four 30-channel EEG recordings on a single subject were performed, each about one month apart. The subject was exposed to 450 MHz MWR modulated at 40 Hz at the 1 g peak spatial average specific absorption rate of 0.3 W/kg. During a recording, 40 cycles of 30 s on-off MWR exposure were used. The artifact-free responses to 126 MWR-ON stimuli and 134 MWR-OFF stimuli were averaged over stimuli and channels.

RESULTS: Regarding EEG signals locked to MWR-OFF stimulus, the enhanced signal level at alpha frequency band and about twice higher signal to noise ratio at 200 to 440 ms after the stimulus have been detected. No remarkable response in EEG signals locked to MWR-ON stimulus.

CONCLUSIONS: The detection of offset effect confirms that there should be an imprint generated by MWR in brain. The results of this preliminary study provide evidence for the detection of MWR-induced ERP in EEG signal and encourage further research in this direction.

A pilot study on the reproductive risks of maternal exposure to magnetic fields from electronic article surveillance systems

Khan MW, Roivainen P, Herrala M, Tiikkaja M, Sallmén M, Hietanen M, Juutilainen J. A pilot study on the reproductive risks of maternal exposure to magnetic fields from electronic article surveillance systems. Int J Radiat Biol. 2018 Oct;94(10):902-908. doi: 10.1080/09553002.2018.1439197. Epub 2018 Feb 26.


PURPOSE: We investigated the feasibility of a large-scale epidemiological study on reproductive effects of intermediate frequency (IF) magnetic field (MF) exposure among cashiers working near electronic article surveillance (EAS) systems.

MATERIALS AND METHODS: The study cohort included 4157 women who had worked as cashiers in supermarkets with EAS devices (considered as exposed) or grocery stores without EAS devices (considered as unexposed) between 2008 and 2015. 536 births and 38 miscarriages occurred among these women during the study period, based on information from nationwide health registries. Measurements were also performed to characterize the MF exposure of cashiers.

RESULTS: Cashiers were found to be exposed to 8.2 MHz MFs only when passing by the gates at short distance. Static fields of about 0.1 mT were observed at cashier's seat. Extremely low frequency MFs were higher at stores without EAS devices. No differences on the risk of miscarriage, reduced birth weight or preterm birth were observed between cashiers in different store types.

CONCLUSIONS: Any further studies should attempt to include study subjects working near EAS systems that produce stronger IF MFs at kHz frequencies. Exposure to ELF MFs should be assessed as a possible confounding factor.

Evaluation of the influence of in vivo exposure to extremely low-frequency magnetic fields on the plasma levels of pro-inflammatory cytokines in rats

Wyszkowska J, Jędrzejewski T, Piotrowski J, Wojciechowska A, Stankiewicz M, Kozak W. Evaluation of the influence of in vivo exposure to extremely low-frequency magnetic fields on the plasma levels of pro-inflammatory cytokines in rats. Int J Radiat Biol. 2018 Oct;94(10):909-917. doi: 10.1080/09553002.2018.1503428. Epub 2018 Sep 28.


PURPOSE: Epidemiological data suggest that there is a link between exposure to extremely low-frequency magnetic fields (ELF-MFs), immune response, and the occurrence of neurodegenerative diseases. The exact nature of this phenomenon remains speculative and requires detailed laboratory investigation. In the present study, we evaluate changes in plasma concentration of pro-inflammatory and regulatory cytokines as well as alternations of the hematological parameters in rats exposed to an ELF-MF.

MATERIALS AND METHODS: Male Wistar rats were repeatedly exposed for either 1 h/day for 7 days, or continuously for 24 h, to a sinusoidal ELF-MF (50 Hz, 7 mT). Control groups were sham exposed for either 1 h/day for 7 days, or continuously for 24 h, respectively. The levels of cytokines: interleukin (IL)-1β, IL-2, IL-6, and IL-10 in plasma obtained from blood samples were determined using enzyme-linked immunosorbent assay (ELISA). The changes in blood parameters were determined using an automatic hematology analyzer in whole blood samples immediately after collection.

RESULTS: We found that a single continuous (lasting 24 h) exposure provoked a significant increase of the plasma IL-1β, IL-6, and IL-2 levels, and caused an elevation in blood parameters, such as white blood cells, lymphocytes, hemoglobin, and hematocrit levels. In contrast, however, repetitive exposure of rats to an ELF-MF for 1 h/day for 7 days did not lead to any changes in plasma levels of cytokines and hematological counts.

CONCLUSIONS: Based on these data we conclude that exposure duration (dose-response) plays a significant role in the immune response, specifically at the cellular level. While single 24 h-lasting exposure provoked changes that indicate an immune alarm stimulation, under the conditions which are typical for therapeutic use of ELF-MFs (repeated short daily exposure) the immune potentially harmful response has not been observed.

Evaluation of the inter-person variability of hazards to the users of BAHA hearing implants caused by exposure to a low frequency magnetic field

Zradziński P. Evaluation of the inter-person variability of hazards to the users of BAHA hearing implants caused by exposure to a low frequency magnetic field.

Int J Radiat Biol. 2018 Oct;94(10):918-925. doi: 10.1080/09553002.2018.1454619. Epub 2018 Apr 4.


PURPOSE: In this work, the inter-person variability of hazards caused by a low frequency magnetic field exposure (of various polarization and homogeneity near to the magneto therapy applicator) to users of bone anchored hearing aid (BAHA) hearing implants were investigated with respect to various head structures.

MATERIAL AND METHODS: The effects of exposure were evaluated by numerical simulations of the electric field (Ein) induced in head phantoms (regular or with implant model). Phantoms mimic head dimensions and thicknesses of layers of skin, fat, skull bones, and brain.

RESULTS:The values of Ein obtained in the phantom of the BAHA user's head were several times (up to 4.5) higher than in a regular person. The highest differences in Ein values were found in the skin and fat tissues - up to 80% in phantoms of various structures (statistically significant differences related to various tissues thicknesses, not-significant with relation to phantom dimensions - Kruskal-Wallis test with Bonferroni correction, p < .017) and up to 3 times with magnetic field spatial distribution (statistically significant with different polarization).

CONCLUSIONS:The results support the need to assess the electromagnetic fields hazards to individual implant user exposed to the magnetic field at a level approaching the exposure limits set by international guidelines.

In silico modelling of influence from low or intermediate frequency magnetic fields on users of wearable insulin pumps

Zradziński P, Karpowicz J, Gryz K. In silico modelling of influence from low or intermediate frequency magnetic fields on users of wearable insulin pumps. Int J Radiat Biol. 2018 Oct;94(10):926-933. doi: 10.1080/09553002.2017.1419305. Epub 2018 Jan 3.


PURPOSE: The aim was to model the effects of exposure to a low or intermediate frequency electromagnetic field (LIF-EMF), characterized by the electric field induced in the body, in order to evaluate how the type of insulin needle and the way it is injected influences the exposed user of a wearable insulin pump.

MATERIAL AND METHODS: Numerical models of exposure scenarios (sources of LIF-EMF, with a dominant magnetic component: 50Hz-1MHz; the insulin needle type; the way it is injected and insulin pump user) were worked out. The influence of the insulin needle on the user's safety (the ratio of the induced electric field in tissues surrounding the needle and tissues of a person without an injection, both exposed identically) were calculated.

RESULTS. The effects of LIF-EMF exposure in insulin pump users were found to be up to approximately 7-times higher, varying with statistically significance (p < .05) with the material of the needle, the way it is injected and the polarization of the affecting magnetic field.

CONCLUSIONS: When steel insulin needles is used, the assessment of user's EMF exposure should be carried out using magnetic field limits at least 5-times lower than given in general international requirements.

Electroencephalographic signals during anesthesia recorded from surface and depth electrodes

Jäntti V, Ylinen T, Subramaniyam NP, Kamata K, Yli-Hankala A, Kauppinen P, Sonkajärvi E.Electroencephalographic signals during anesthesia recorded from surface and depth electrodes. Int J Radiat Biol. 2018 Oct;94(10):934-943. doi: 10.1080/09553002.2018.1478159. Epub 2018 Jun 22.


PURPOSE: Anesthesiologists have increasingly started to use EEG-based indexes to estimate the level and type of unconsciousness. However, the physiology and biophysics are poorly understood in anesthesiological literature.

METHODS: EEG was recorded from electrodes on the surface of head, including scalp, as well as DBS (deep brain stimulation) electrodes implanted deep in the brain. Mathematical modeling with a realistic head model was performed to create illustrative images of the sensitivity of electrode montages.

RESULTS: EEG pattern of anesthesia, burst-suppression, is recordable outside of scalp area as well in the depth of brain because the EEG current loops produce recordable voltage gradients in the whole head. The typical electrodes used in anesthesia monitoring are most sensitive to basal surface of frontal lobes as well as frontal and mesial parts of temporal lobes.

CONCLUSIONS: EEG currents create closed-loops, which flow from the surface of the cortex and then return to the inside of the hemispheres. In the case of widespread synchronous activity like physiological sleep or anesthesia, the currents recorded with surface and depth electrodes return through the base of brain and skull. 


Toxicity assessment of biological suspensions using the dielectric impedance spectroscopy technique

Muñoz S, Sebastián JL, Antoranz P, García-Cambero JP, Sanchis-Otero A.Toxicity assessment of biological suspensions using the dielectric impedance spectroscopy technique. Int J Radiat Biol. 2018 Oct;94(10):944-950. doi: 10.1080/09553002.2018.1439196. Epub 2018 Feb 21.


PURPOSE: This article studies the variation of the electromagnetic parameters of a suspension of zebrafish (Danio rerio) embryos to assess its potential applications to toxicological and biomedical research areas.

MATERIALS AND METHODS: For this purpose, the dielectric impedance spectroscopy technique is applied to a modified coaxial line enclosing the biological suspension to be characterized in the frequency range from 100 kHz to 100 MHz. The electrical parameters of the suspension under test were obtained by fitting the impedance spectra to the resulted from the simulation of the test fixture using finite elements (FE).

RESULTS: Variation of the complex permittivity of the suspensions makes possible to identify viable and non-viable embryos after a toxic exposure, as well as different stages during the blastula period of embryonic development of the zebrafish.

CONCLUSIONS: The approach presented here, combining experimental and simulation techniques, may provide a basis for a non-invasive method to assess toxicity in any biological suspension.