Monday, October 4, 2021

Recent Research on Wireless Radiation and Electromagnetic Fields

I have been circulating abstracts of newly-published scientific papers on wireless radiation and electromagnetic fields (EMF) about once a month since August 2016. These updates are sent to several hundred EMF scientists around the world.

The latest additions appear below. The complete collection of abstracts now covers more than 1,300 scientific papers. This 1,048-page document (pdf) can be downloaded by clicking on the following link:


Note: This link will change when new abstracts are added to the collection.

Recent Papers

Effect of Radiation Emitted by Wireless Devices on Male Reproductive Hormones: A Systematic Review

Maluin Sofwatul Mokhtarah, Osman Khairul, Jaffar Farah Hanan Fathihah, Ibrahim Siti Fatimah. Effect of Radiation Emitted by Wireless Devices on Male Reproductive Hormones: A Systematic Review. Frontiers in Physiology. 12:1568. 2021. doi:10.3389/fphys.2021.732420.
 
Abstract

Exposure to radiofrequency electromagnetic radiation (RF-EMR) from various wireless devices has increased dramatically with the advancement of technology. One of the most vulnerable organs to the RF-EMR is the testes. This is due to the fact that testicular tissues are more susceptible to oxidative stress due to a high rate of cell division and mitochondrial oxygen consumption. As a result of extensive cell proliferation, replication errors occur, resulting in DNA fragmentation in the sperm. While high oxygen consumption increases the level of oxidative phosphorylation by-products (free radicals) in the mitochondria. Furthermore, due to its inability to effectively dissipate excess heat, testes are also susceptible to thermal effects from RF-EMR exposure. As a result, people are concerned about its impact on male reproductive function. The aim of this article was to conduct a review of literature on the effects of RF-EMR emitted by wireless devices on male reproductive hormones in experimental animals and humans. According to the findings of the studies, RF-EMR emitted by mobile phones and Wi-Fi devices can cause testosterone reduction. However, the effect on gonadotrophic hormones (follicle-stimulating hormone and luteinizing hormone) is inconclusive. These findings were influenced by several factors, which can influence energy absorption and the biological effect of RF-EMR. The effect of RF-EMR in the majority of animal and human studies appeared to be related to the duration of mobile phone use. Thus, limiting the use of wireless devices is recommended.

Conclusion

Existing animal and human data on the effect of RF-EMR emitted from wireless devices on male reproductive hormones are inconsistent and difficult to evaluate due to the heterogeneity of study design. However, most studies are consistent with the assertion that long-term exposure to RF-EMR from mobile phones and Wi-Fi devices can disrupt male reproductive hormones, particularly testosterone. Thus, avoiding long-term and excessive use of mobile phone is advisable to reduce the detrimental effect of RF-EMR.


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Challenges on the effect of cell phone radiation on mammalian embryos and fetuses: a review of the literature


Maryam Mahaldashtian, Mohammad Ali Khalili, Fatemeh Anbari, Mohammad Seify, Manuel Belli. Challenges on the effect of cell phone radiation on mammalian embryos and fetuses: a review of the literature. Zygote. 2021 Sep 29;1-7. doi: 10.1017/S0967199421000691.

Abstract

Cell phones operate with a wide range of frequency bands and emit radiofrequency-electromagnetic radiation (RF-EMR). Concern on the possible health hazards of RF-EMR has been growing in many countries because these RF-EMR pulses may be absorbed into the body cells, directly affecting them. There are some in vitro and in vivo animal studies related to the consequences of RF-EMR exposure from cell phones on embryo development and offspring. In addition, some studies have revealed that RF-EMR from cellular phone may lead to decrease in the rates of fertilization and embryo development, as well as the risk of the developmental anomalies, other studies have reported that it does not interfere with in vitro fertilization or intracytoplasmic sperm injection success rates, or the chromosomal aberration rate. Of course, it is unethical to study the effect of waves generated from cell phones on the forming human embryos. Conversely, other mammals have many similarities to humans in terms of anatomy, physiology and genetics. Therefore, in this review we focused on the existing literature evaluating the potential effects of RF-EMR on mammalian embryonic and fetal development.


Excerpts

Mobile phones are commonly placed on the lap or in pockets (Swerdlow et al., 2011), therefore exposing the genital area to RF-EMF. Germ cells are more susceptible to RF-EMF, as they are rapidly dividing through meiosis and mitosis. EMF induces modifications in cellular levels such as activation of voltage-gated calcium channels, formation of free radicals, protein misfolding and DNA damage (Altun et al., 2018). In the general population, pregnant women are at specific risk of exposure to environmental RF-EMF because of their higher oxygen consumption and amniotic fluid-induced ROS production (Çiğ and Nazıroğlu, 2015) (Fig. 1). Individuals should reduce their rate of exposure to RF-EMF-emitting devices including mobile phones (Okechukwu, 2020) as electromagnetic waves enhanced the amount of oxygen free radicals in the body that led to disturbance of spermatogenesis process and variations in spermatozoa membrane, which resulted in changes in capacitation, acrosome reaction and therefore disorder in the process of spermatozoa binding to the oocyte and failure of normal fertilization both in vivo and in vitro (Fatehi et al., 2018). In addition, exposure to RF may lead to a decline in ovarian follicle reservoirs at the start of the prepubertal time (Türedi et al., 2016).

To reduce the contact with RF-EMR radiated by cell phones, people should avoid keeping their phones inside their pockets, also use of hand-free materials and gadgets and mobile covers limit direct expose of cell phones to the body (Okechukwu, 2020). Also, people do not appreciate that a cell phone is a small base station and usually underrate the importance of distance between the cell phone and the body (Cousin and Siegrist, 2010). In analyzing the relationship between the distance of cell phone antenna from the body and SAR, Hossain and colleagues reported that increasing the distance of cell phone from the body led to diminishing of both electric and magnetic field strength to the body, therefore reducing SAR values (Hossain et al., 2015). Furthermore, it is known that the EMF decreases with distance and magnetic induction...

Conclusion

At this time, it is difficult from the available animal studies to document confidently the role of RF-EMR exposure on human embryo development, both in vivo and in vitro. Further investigations with complementary techniques will be necessary to understand the mechanism of action of RF-EMR emitted by cell phones and the consequences on mammals, particularly human beings.

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An Exploration of the Effects of Radiofrequency Radiation Emitted by Mobile Phones and Extremely Low Frequency Radiation on Thyroid Hormones and Thyroid Gland Histopathology

Alkayyali T, Ochuba O, Srivastava K, Sandhu JK, Joseph C, Ruo SW, Jain A, Waqar A, Poudel S. An Exploration of the Effects of Radiofrequency Radiation Emitted by Mobile Phones and Extremely Low Frequency Radiation on Thyroid Hormones and Thyroid Gland Histopathology. Cureus. 2021 Aug 20;13(8):e17329. doi: 10.7759/cureus.17329.

Abstract

The use of mobile phones has widely increased over the last two decades. Mobile phones produce a radiofrequency electromagnetic field (RF-EMF), a form of non-ionizing radiation. In contrast to the ionizing radiation proven to cause DNA damage, the harmful effects of non-ionizing radiation on the human body have not been discovered yet. The thyroid gland is among the most susceptible organs to mobile phone radiation due to its location in the anterior neck. Our purpose in this literature review is to explore the effects of the electromagnetic field (EMF), especially radiofrequency emitted from mobile phones, on thyroid hormones and thyroid gland histopathology. We searched PubMed and Google Scholar databases for relevant studies published after the year 2000, using the following keywords: 'cell phones', 'mobile phones', 'telephones', 'electromagnetic fields', 'radiofrequency radiation', 'microwaves', 'thyroid gland', 'thyroid hormones', and 'thyroid cancer'. Our review revealed that mobile phone radiofrequency radiation (RFR) might be associated with thyroid gland insufficiency and alterations in serum thyroid hormone levels, with a possible disruption in the hypothalamic-pituitary-thyroid axis. The review also showed histopathological changes in the thyroid gland follicles after exposure of rats to non-ionizing radiation. The results were directly related to the amount and duration of exposure to EMF radiation. Further human studies exploring thyroid gland hormones, microscopic morphology, and thyroid cancer are highly recommended for future researches.

Conclusions

This article aimed to explore the effects of RF-EMF and ELF-EMF on the thyroid gland hormones and histopathology. Studies collected in this review showed that GSM mobile phone RFR could be associated with alterations in T3, T4, and TSH serum hormone levels. EMF emitted from mobile phones could disrupt the function of the HPT axis and lead to thyroid insufficiency. In addition, EMF could lead to hyperstimulation of thyroid gland follicles, causing oxidative stress and apoptosis of follicular cells. Most studies revealed a proportional correlation between thyroid gland dysfunction and the exposure duration, intensity, and SAR value of radiation. Moreover, non-ionizing radiation was seen to be significantly associated with histopathological changes in the thyroid gland follicles. The exposure duration and intensity also determined the degree of morphological damage occurring in the thyroid gland tissue. Non-ionizing EMF radiation might be responsible for the recent increase in the incidence of thyroid insufficiency and cancer in the general population. However, not enough data was found related to thyroid cancer risk with non-ionizing radiation exposure. Keeping in mind the ethical considerations, we recommend future observational studies be conducted on human beings to further explore the association of non-ionizing radiation emitted from mobile phones on the thyroid gland's hormones, histopathology, and cancers over the long term.


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Mobile Phone Use and Time Trend of Brain Cancer Incidence Rate in Korea


Kyung-Hwa Choi, Johyun Ha, Sanghyuk Bae, Ae-Kyoung Lee, Hyung-Do Choi, Young Hwan Ahn, Mina Ha, Hyunjoo Joo, Ho-Jang Kwon, Kyu-Won Jung, Mobile Phone Use and Time Trend of Brain Cancer Incidence Rate in Korea. 20 September 2021. doi: 10.1002/bem.22373.

Abstract

This study evaluated the time trends in mobile phone subscriber number by mobile network generation (G) and brain cancer incidence by type in Korea. We obtained data from the Information Technology Statistics of Korea (1984–2017) and Korea Central Cancer Registry (1999–2017). The average annual percent change was estimated using Joinpoint regression analysis. We evaluated 29,721 brain cancer cases with an age-standardized incidence rate (ASR) of 2.89/100,000 persons. The glioma and glioblastoma annual ASR significantly increased in 2.6% and 3.9% of males and 3.0% and 3.8% of females, respectively. The ASR for frontal lobe involvement was the highest. The ASR of gliomas of unspecified grade annually increased by 7.8%; those for unspecified topology and histology decreased. The incidence of glioma, glioblastoma, frontal, temporal, and high-grade glioma increased among those aged ≥60 years. No association was observed between the mobile phone subscriber number and brain cancer incidence in Korea. Furthermore, long-term research is warranted because of the latency period of brain cancer.

Grant sponsor: ICT R&D program of MSIT/IITP [2019-0-00102, A study on public health and safety in a complex EMF environment].

My summary of results:
  • Glioma incidence increased over time (1999-2017) for adults aged 60 years and over.
  • Glioblastoma incidence increased over time for adults aged 60 years and over.
  • Unspecified brain tumor incidence decreased over time for adults aged 60 years and over.
  • High-grade glioma incidence increased over time for male and female adults aged 60 years and over.
  • The trend over time in standardized incidence of glioma exceeded the predicted relative risk of 1.5 based on mobile phone subscriber number.
  • The trend over time in standardized incidence of glioblastoma exceeded the predicted relative risk of 1.5 based on mobile phone subscriber number.
  • The trend over time in standardized incidence of brain cancer in the frontal lobe exceeded a predicted relative risk of 1.5 based on mobile phone subscriber number.
Excerpts

... According to the type of histology, the incidence of glioma was higher than that of other types, and it was significantly increased in both sexes (AAPC [95% CI], male: 2.6% [2.1, 3.2], female: 3.0% [2.1, 3.8]), whereas those of total brain cancers were not (AAPC [95% CI], male: 0.2% [−0.3, 0.6], female: 0.1% [−0.3, 0.5]). In particular, the incidence of glioblastoma increased more than that of other gliomas. The incidence of cancers with unspecified histology statistically decreased in both sexes (AAPC [95% CI], male: 7.9% [−9.6, −6.1], female: 7.8% [−8.9, −6.7]). According to the type of topology, the ASR of frontal lobe involvement (male: 0.53, female: 0.45) was higher than that of the temporal and parietal lobes. The ASR of cancers with unspecified topology decreased by 4.6% per year in males and 3.8% per year in females, whereas that of cancers of the other lobes increased. According to the type of grade, the incidence and AAPC of high-grade gliomas were higher than those of low-grade gliomas. The ASR of gliomas of unspecified grade increased by 7.8% per year, whereas those of unspecified topology (3.8% per year) and unspecified histology (7.8% per year) decreased.

... The incidence of glioma, glioblastoma, frontal, temporal, and high-grade glioma increased among those aged ≥60 years, and increased significantly among those aged ≥70 years (AAPC [95% CI]): glioma (male: 6.9 [5.6, 8.2], female: 8.5 [6.5, 10.6]); glioblastoma (male: 8.1 [6.1, 10.2], female: 9.9 [7.3, 12.5]); frontal (male: 6.2 [4.5, 8.0], female: 6.6 [4.0, 9.4]); temporal (male: 5.8 [2.9, 8.7], female: 7.1 [4.6, 9.7]); high-grade glioma (male: 7.5 [5.8, 9.3], female: 9.2 [7.0, 11.4]). There were no differences in the trend for unspecified brain cancer by histology, topology, or grade of glioma according to age group...

This study has several limitations. First, it is difficult to prove whether exposure to RF-EMF from mobile phones increases the incidence of brain cancers because this is a descriptive study. Further studies are required to evaluate the association between brain cancer incidence and mobile phone subscribers by age group, because this study shows different results for each age group, such as an increase in the incidence of brain cancer among older adults. Therefore, we could not determine whether the increase in brain cancer incidence, especially glioma and glioblastoma, was associated with an increase of mobile phone subscribers in older age groups. Second, it was not possible to calculate the predicted incidence according to the mobile phone subscription by sex and age. For this, it is better to acquire detailed information such as sex, age, and residential address of mobile phone subscribers in future studies and analyze them further. Studies have revealed a latency period of more than 30 years for cancer [Sadetzki et al., 2005]. However, data on cancer incidence are only available for approximately 20 years in Korea. Hence, further analysis is required to verify our results.

This study found no evidence of an increase in brain cancer incidence associated with the increasing number of mobile phone subscribers in Korea. Further research is warranted using detailed information on mobile phone subscriptions, with research carried out for longer durations considering the latency period for brain cancer.


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5G New Radio Requires the Best Possible Risk Assessment Studies: Perspective and Recommended Guidelines

Mats-Olof Mattsson, Myrtill Simkó, Kenneth R. Foster. 5G New Radio Requires the Best Possible Risk Assessment Studies: Perspective and Recommended Guidelines. Frontiers in Communications and Networks. Vol 2:49. 2021. doi: 10.3389/frcmn.2021.724772.
   
Abstract

The development and establishment of mobile communication technologies has necessitated assessments of possible risks to human health from exposures to radio-frequency electromagnetic fields (RF EMF). A number of expert committees have concluded that there is no evidence for such risks as long as exposures are at or below levels that do not allow tissue heating. These assessments have been based primarily on studies investigating frequencies up to 6 GHz including frequencies similar to those used by two of three major bands of fifth generation (more accurately 5G New Radio or 5G NR) of mobile communication. Bioeffects studies in so-called high-band at 25–39 GHz are particularly sparse. Future assessments relevant for these frequencies will need to rely on still unperformed studies. Due to few available studies at 5G NR “high band” frequencies, and questions raised by some existing studies, a recent review recommended a wide range of RF biostudies be done at 5G NR “high band” frequencies. It is of importance that such studies be done using the best possible science. Here we suggest factors to consider when performing future studies in this area. The present focus is on laboratory studies to clarify biological effects of radiofrequency (RF) energy at 5G “high band” frequencies and, more generally at millimeter wave (mm-wave) frequencies (30-300 GHz) which will be increasingly used by communications technologies in the future. Similar comments would apply to epidemiology and exposure assessment studies, but those are not the focus of the present Perspective.

Open access paper:  https://www.frontiersin.org/article/10.3389/frcmn.2021.724772

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Mapping of static magnetic fields near the surface of mobile phones


L. Zastko, L. Makinistian, A. Tvarožná, F. L. Ferreyra & I. Belyaev. Mapping of static magnetic fields near the surface of mobile phones. Scientific Reports. 11:19002. 2021. doi: 10.1038/s41598-021-98083-9.

Abstract

Whether the use of mobile phones (MP) represents a health hazard is still under debate. As part of the attempts to resolve this uncertainty, there has been an extensive characterization of the electromagnetic fields MP emit and receive. While the radiofrequencies (RF) have been studied exhaustively, the static magnetic fields (SMF) have received much less attention, regardless of the fact there is a wealth of evidence demonstrating their biological effects. We performed 2D maps of the SMF at several distances from the screen of 5 MP (models between 2013 and 2018) using a tri-axis magnetometer. We built a mathematical model to fit our measurements, extrapolated them down to the phones’ screen, and calculated the SMF on the skin of a 3D head model, showing that exposure is in the µT to mT range. Our literature survey prompts the need of further research not only on the biological effects of SMF and their gradients, but also on their combination with extremely low frequency (ELF) and RF fields. The study of combined fields (SMF, ELF, and RF) as similar as possible to the ones that occur in reality should provide a more sensible assessment of potential risks.

Excerpts

The maximum SMF estimated in this work (6.6 mT) and others’ (20 mT) 14 are far below the 400 mT exposure limit for the general public recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP)26. This might lead to the temptation of completely disregarding SMF as a variable of interest when assessing MP fields. In fact, a recent fact sheet from the Swiss Federal Office of Public Health 13 completely omitted any reference to SMF. Nevertheless, the sole capacity of these fields of inducing potentially harmful biological effects such as promotion of the production of reactive oxygen species (ROS) 21 should be enough to consider them seriously. As for the possible underlying mechanisms of interaction, the one based on magnetite nanoparticles 27 is of particular interest because these nanoparticles have been found in the human brain 28,29. Besides the brain, the ear is of an obvious interest for its proximity to the upper HS of MP. Interestingly, magnetic material was reported on the lagenal otoliths of fish and birds 30 (although this structure is not conserved in mammals). To the best of our knowledge, there have not been studies reporting the search of magnetic materials as constituents of the human inner ear. In this regard, it is to be mentioned that some epidemiological studies found an association between MP use and tinnitus (the perception of a sound in the absence of an external source), while a meta-analysis found no association 31...

Our measurements and calculations, along with the preceding discussion of the literature, prompt the need of further studies of the biological effects of the SMF and RF EMF generated by MP. We suggest special emphasis should be put into (1) inhomogeneous SMF (with a detailed characterization of both, intensities and gradients), and (2) combination of SMF (homogeneous and inhomogeneous) with RF EMF, with a fine sweeping of the parameters within the range of typical exposures (in opposition to testing single combinations). In even more complicated experiments, ELF EMF should also be considered 12 since their relationship with SMF have been long known 53. Lastly it is worth mentioning that substantial reduction of the SMF from MP could be accomplished by replacing the standard electrodynamic loudspeakers and microphones (which include a permanent magnet) by their capacitive counterparts (which do not).


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Radio-Frequency Electromagnetic Fields: Simultaneous Exposure to Infinite Sources From Typical Base Stations

A. Linhares, A. P. de Azevedo and L. C. Fernandes. Radio-Frequency Electromagnetic Fields: Simultaneous Exposure to Infinite Sources From Typical Base Stations. IEEE Antennas and Propagation Magazine. doi: 10.1109/MAP.2021.3106829.

Introduction

This article shows that simultaneous exposure to infinite electromagnetic field (EMF) sources from typical base stations transmitting at multiple frequency bands is lower than international limits. Considering a real base station density and conservative path loss models, we show that the power density at a given location can be modeled by a convergent infinite series. To validate this model, we apply it to Brasília, Brazil, and compare the results with measurements. While the proposed model shows that the exposure ratio (ER) will not exceed 2.62%, the highest measured value reaches 85% of this estimation.

Conclusions

In this article, we proposed a method to estimate an upper limit for the TER due to infinite sources of typical base stations. When assessing human exposure to RF EMFs due to specific base stations, the exposure caused by all other base stations can be estimated using the model. The model was applied using base station density data from Brasília and shows that simultaneous exposure from infinite cellular macro base stations distributed as shown in Figure 2 will not be more than 2.62% of the ICNIRP limits. It was validated using simulations and more than 3,000 measurements, and our results agree with them regardless of the probe location. However, for a more conservative approach, when assessing individual base stations, the model can be used to estimate an upper limit for all other base stations (i.e., it provides an exposure addition to the results of the base station under test).

The model is not bounded to a specific frequency band and generic enough to be used by superimposing different categories of base stations, such as micro and macro cells. It may also be employed for 5G, but due to its antenna beamforming, the approach would be more conservative since RF EMF exposure may decrease due to its dynamic directional characteristics. This topic will be the subject of future studies. To ensure the reproducibility of the results in this article, the equations were implemented in numeric code and are available in [20]. The code and data to generate the results in Tables 1 and 2 and Figures 4, 5, 7, 8, and 9 are also available.


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Alteration of intrapancreatic serotonin, homocysteine, TNF-α, and NGF levels as predisposing factors for diabetes following exposure to 900-MHz waves

Gholamali Jelodar, Mansour Azimzadeh, Fatemeh Radmard, Narges Darvishhoo. Alteration of intrapancreatic serotonin, homocysteine, TNF-α, and NGF levels as predisposing factors for diabetes following exposure to 900-MHz waves. Toxicol Ind Health. 2021 Aug;37(8):496-503. doi: 10.1177/07482337211022634.

Abstract

Exposure to mobile phone radiation causes deleterious health effects on biological systems. The objects of this study were to investigate the effect of 900-MHz radiofrequency waves (RFW) emitted from base transceiver station antenna on intrapancreatic homocysteine (Hcy), tumor necrosis factor-α (TNF-α), and nerve growth factor (NGF) as predisposing factors involved in pancreatic beta cell damage. Thirty male rats (Sprague-Dawley, 200 ± 10 g) were randomly divided into the control (without any exposure) and exposed groups: short time (2 h/day), long time (4 h/day), and exposed to 900-MHz RFW for 30 consecutive days. On the last days of the experiment, animals were killed and pancreas tissue was dissected out for evaluation of serotonin, Hcy, TNF-α, and NGF. There was a significant decrease in the serotonin and NGF levels in the pancreatic tissue of exposed groups compared to the control group (p < 0.05). Also, the levels of serotonin and NGF in the long-time exposure were significantly lower than the short-time exposure (p < 0.05). However, levels of Hcy and TNF-α were significantly increased in the pancreas of exposed groups compared to the control groups (p < 0.05). Exposure to 900-MHz RFW decreased pancreatic NGF and serotonin levels and increased the proinflammatory markers (Hcy and TNF-α), which can be a predisposing factor for type 2 diabetes.


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The Research and Safety Discussion of Electromagnetic Radiation in Electric Vehicles

X. Wang et al. The Research and Safety Discussion of Electromagnetic Radiation in Electric Vehicles. 2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021, pp. 1-3, doi: 10.1109/ACES53325.2021.00038.

Abstract

To study the electromagnetic radiation in electric vehicles for human exposure, the electric field (6 Hz to 3 GHz) and magnetic field (6 Hz to 30 MHz) strengths in electric vehicles of driving mode, charging mode and stationary mode are measured, and the characteristics of the electric and magnetic field in electric vehicles are analysed and studied here. The studies show that the electromagnetic radiation of electric vehicles is mainly consisted of electromagnetic wave from 6 Hz to 500 Hz, and it might be higher in driving mode than that of charging mode and stationary mode. The abnormal values of electromagnetic radiation in electric vehicles often occur in driving mode, and usually appear in the front of the electric vehicles.


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Oxidative Stress and NADPH Oxidase: Connecting Electromagnetic Fields, Cation Channels and Biological Effects

Christos D Georgiou, Lukas H Margaritis. Oxidative Stress and NADPH Oxidase: Connecting Electromagnetic Fields, Cation Channels and Biological Effects. Int J Mol Sci. 2021 Sep 17;22(18):10041. doi: 10.3390/ijms221810041.

Abstract

Electromagnetic fields (EMFs) disrupt the electrochemical balance of biological membranes, thereby causing abnormal cation movement and deterioration of the function of membrane voltage-gated ion channels. These can trigger an increase of oxidative stress (OS) and the impairment of all cellular functions, including DNA damage and subsequent carcinogenesis. In this review we focus on the main mechanisms of OS generation by EMF-sensitized NADPH oxidase (NOX), the involved OS biochemistry, and the associated key biological effects.

Excerpts

Conclusions

On the basis of the above findings, an EMF mechanism can involve ROS formation due to membrane and voltage-gated cation channel function deterioration [2,3,7,8] followed by stress activation and heat-shock protein overexpression [56], which may be associated with behavioural and physiological effects such as blood–brain barrier disruption, memory malfunction, changes in gene expression [53], autophagy, apoptosis [53,84] (especially due to modulation [85]), lifespan reduction, DNA damage, and cancer [18].

Theory and Research Perspectives for a Conclusive Linking of EMFs with ROS/RNS

EMF induction of OS via increased concentration of free radicals, has been challenged (by ICNIRP) mainly due to (i) the claimed non-ionizing nature of EMF (ELF/RF), where no covalent bonds are broken at non-thermal intensities, or so the argument goes, and because (ii) the measurement of OS is performed by non-specific methods. Indeed, OS is measured, either by methods that are not specific to the identification of generated free radicals, or indirectly by certain oxidative modifications they cause on key biological molecules (e.g., DNA damage, lipid/protein peroxidation, etc.).

Man-made EMFs do not possess high enough energy to generate free radicals, e.g., on freely moving single H2O molecules by a single photon. However, the individual EMF of such photons are fully synchronized (in terms of frequency, polarization, phase, and propagation direction), thereby producing cumulative macroscopic electric and magnetic fields and electromagnetic radiation (EMR). Nonetheless, these may be additively high enough to break covalent bonds and may directly generate free radicals. Secondly, concentrations of naturally occurring free radicals can increase by the prevention of either (i) reactions between them (e.g., appearing as the aforementioned reactants •NO + O2•− and products •OH + •NO2), or (ii) the reassociation of free radical pairs generated enzymically as transition states. Such prevention can be assisted by the EMF-induced free radical pair mechanism [86,87]. Here, EMFs can prevent the reassociation of free radical pairs by reversing the spin direction of the single electron in one of these free radicals by flipping the direction of its magnetic field component. Thus, the magnetically affected free radical pair ends up consisting of two free radicals, the electron spins of which have become parallel, thereby preventing their re-binding and indirectly increasing their concentration. The free radical pair mechanism has been accounted for by the International Agency for Research on Cancer for the classification of the RF EMFs in the Group 2B category of “possibly carcinogenic to humans” [88]. These two mechanisms of free radical-concentration increase corroborate with the preliminary finding that ELF EMFs increase the concentration of O2•− by many fold in various organs of mice exposed to the ICNIRP limit of 100 µT at 50 Hz (pending publication by Dr. Georgiou’s lab).

Therefore, methods for the in vivo specific detection of the key biological free radicals •OH and O2•− ([89,90]) are needed in order to unequivocally prove the generation of carcinogenic OS by EMFs.


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Residential extremely low frequency magnetic fields and skin cancer


Muhammad Waseem Khan, Jukka Juutilainen, Jonne Naarala, Päivi Roivainen. Residential extremely low frequency magnetic fields and skin cancer. Occup Environ Med. 2021 Sep 30;oemed-2021-107776. doi: 10.1136/oemed-2021-107776.

Abstract

Objective: Photoinduced radical reactions have a fundamental role in skin cancer induced by ultraviolet radiation, and changes in radical reactions have also been proposed as a mechanism for the putative carcinogenic effects of extremely low frequency (ELF) magnetic fields (MFs). We assessed the association of melanoma and squamous cell carcinoma with residential MF exposure.

Methods: All cohort members had lived in buildings with indoor transformer stations (TSs) during the period from 1971 to 2016. MF exposure was assessed based on apartment location. Out of the 225 492 individuals, 8617 (149 291 person-years of follow-up) living in apartments next to TSs were considered as exposed, while individuals living on higher floors of the same buildings were considered as referents. Associations between MF exposure and skin cancers were examined using Cox proportional hazard models.

Results: The HR for MF exposure ≥6 month was 1.05 (95% CI 0.72 to 1.53) for melanoma and 0.94 (95% CI 0.55 to 1.61) for squamous cell carcinoma. Analysis of the age at the start of residence showed an elevated HR (2.55, 95% CI 1.15 to 5.69) for melanoma among those who lived in the apartments when they were less than 15 years old. This finding was based on seven exposed cases.

Conclusions: The results of this study suggested an association between childhood ELF MF exposure and adult melanoma. This is in agreement with previous findings suggesting that the carcinogenic effects of ELF MFs may be associated particularly with childhood exposure


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Electromagnetic Fields Modify Redox Balance in the Rat Gastrointestinal Tract

Sieroń Karolina, Knapik Katarzyna, Onik Grzegorz, Romuk Ewa, Birkner Ewa, Kwiatek Sebastian, Sieroń Aleksander. Electromagnetic Fields Modify Redox Balance in the Rat Gastrointestinal Tract. Frontiers in Public Health. 9:1283. 2021. doi:10.3389/fpubh.2021.710484.
   
Abstract

Objective: The aim of the study was to assess the influence of electromagnetic fields with divergent physical properties on the prooxidative and antioxidative balances in homogenates of the tongue, salivary glands, esophagus, stomach, and small and large intestines of rats.

Material and Methods: Forty rats were randomly divided into four equal groups, namely, a control group, a group exposed to low-frequency electromagnetic fields (LF-EMFs; frequency: 50 Hz; intensity: 10 kV/m; magnetic induction: 4.3 pT), a group exposed to radiofrequency electromagnetic fields (RF-EMFs) emitted by mobile phones (frequency: 900 MHz), and a group exposed simultaneously to LF-EMFs and RF-EMFs emitted by mobile phones. After 28 consecutive days of the experiment, the following pro- and antioxidative markers were assessed in the gastrointestinal tract homogenates: superoxide dismutase (SOD) and its two isoenzymes (Mn-SOD, Cu,Zn-SOD) catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), total antioxidative capacity (TAC), total oxidative status (TOS), and malondialdehyde (MDA).

Results: In rats exposed to LF-EMFs, higher concentrations of the markers of prooxidant processes, MDA or TOS, were observed in the salivary glands, esophagus, and small intestine homogenates in comparison with the control group. Additionally, in the group of rats opposite to the control, antioxidant activity was observed. The main differences included a higher activity of Cu,Zn-SOD in homogenates of the tongue, salivary glands, and esophagus as well as decreased activity of CAT in homogenates of the tongue, esophagus, and small intestine. In animals exposed to RF-EMFs, the concentration of TOS was higher in the large intestine than in control rats. The main difference of antioxidant activity was presented by decreased Cu,Zn-SOD in homogenates of the salivary glands, stomach, small and large intestine as well as CAT in homogenates of the tongue, esophagus, stomach, and small and large intestine. Moreover, in rats exposed simultaneously to LF-EMFs and RF-EMFs, a lower concentration of TOS was observed. Antioxidant activity was presented by a decreased activity of CAT in homogenates of the tongue, esophagus, stomach, and small and large intestine in comparison to the control group.

Conclusion: Among those applied in the study, electromagnetic fields of a low-frequency caused the most significant disturbances of oxidative stress in the rat gastrointestinal tract.

Open access paper: https://www.frontiersin.org/article/10.3389/fpubh.2021.710484

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Near Field Radio-Frequency Electromagnetic Field Exposure of a Western Honey Bee

D. Toribio, W. Joseph, A. Thielens. Near Field Radio-Frequency Electromagnetic Field Exposure of a Western Honey Bee. IEEE Transactions on Antennas and Propagation, doi: 10.1109/TAP.2021.3111286.

Abstract

It has been suggested that the wireless network evolution to smaller carrier wavelengths (from 2G to 5G) increases radio-frequency electromagnetic field (RF-EMF) absorption in Western Honey Bees (Apis mellifera). It is unknown whether the radiation performance of antennas is stable when an insect appears in their vicinity. In this research, the absorbed power in a worker honey bee and the influence of the bee’s presence on antennas’ radiation performance is investigated for the newly used frequencies in 5G networks, from 6-240 GHz. To these aims, numerical simulations using the finite-difference time-domain method were performed, in which a bee model, obtained by micro-CT scanning, was employed. These simulations showed that in the near field, the absorbed power can increase by a factor of 53, from 6-240 GHz. This is a factor of 7 higher than the increase reported in the far field, in previous studies. Furthermore, the simulations revealed that antennas’ radiation efficiency can decrease by up to -40 % when a bee appears in the near field. Likewise, it was found that the gain pattern depends on the separation distance between the bee and the antenna, with a stronger dependency for higher frequencies.

Excerpts

CONCLUSION  Numerical simulations using finite-difference time-domain analysis were executed to calculate the radio-frequency electromagnetic fields (RF-EMFs) in and around a worker Western Honey Bee (Apis mellifera). This lead to the quantification of the whole-body averaged absorbed radio-frequency power Pabs, under near-field exposure, in the frequency range of 6-240 GHz. The simulations showed that, in the near field, Pabs decreases as the separation distance between the bee and the dipole increases, and increases as frequency increases. The frequency behavior of Pabs in the near field is thus different to its far-field behavior, since, for a given accepted power and distance, in the near field Pabs increases with frequency (an average of 30.5 dB from 6-240 GHz), while in the far field Pabs in the worker bee is maximized at 12 GHz. This near-field increase in Pabs as a function of frequency, can be a factor of 7 higher than the far-field increase.

Moreover, these simulations allowed the study of the influence of the bee’s position (0.1 −10 λ from the dipoles) in the radiation performance of the dipoles. In particular, it was found that as the separation distance increases, the dipoles’ isotropic gain decreases and approaches their free-space gain. Also, it was noted that as a result of the near-field frequency behavior of Pabs, the dipoles’ radiation efficiency decreases with increasing frequency and increases with increasing separation distance. Additionally, it was acknowledged that the gain pattern in the direction where the bee approaches the antenna depends on the separation distance between the bee and the antenna, with a stronger dependency for higher frequencies. This is important for 5G telecomunication networks, because they rely on infrastructure (antennas) whose performance can be influenced by the presence of free-flying insects.

https://ieeexplore.ieee.org/document/9539081

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Sublethal neonicotinoid exposure attenuates the effects of electromagnetic fields on honey bee flight and learning

S. Shepherd, M.A.P. Lima, E.E. Oliveira, S.M. Sharkh, H. Aonuma, C.W. Jackson, P.L. Newland. Sublethal neonicotinoid exposure attenuates the effects of electromagnetic fields on honey bee flight and learning, Environmental Advances. Volume 4. 2021. 100051. doi:10.1016/j.envadv.2021.100051.

Abstract

Many environmental stressors are currently implicated in the decline of flying insects in general, and important pollinator species such as the honey bee. Recent studies have shown that extremely low frequency electromagnetic fields (ELF EMFs) affect many aspects of insect behaviour and cognition which raises the potential that ELF EMFs could interact with other environmental stressors such as neonicotinoid insecticides to have even greater impact on the decline of flying insects. Here we analysed the effects of individual and combined exposure of the honey bee to 50 Hz EMFs and sublethal exposure to clothianidin, in a tethered flight assay and an olfactory appetitive learning assay. Clothianidin was significantly toxic to bees and exposure to field-realistic levels (2.00 ng/bee) led to 25% mortality. Exposure to ELF EMFs alone led to a significant increase in wingbeat frequency at levels above 100 µT. Prior exposure to clothianidin attenuated the effects of EMFs on wingbeat frequency. Exposure to EMFs alone reduced learning of a proboscis extension reflex (PER). Prior exposure to low doses of clothianidin attenuated the effects of EMFs on PER. These results indicate no evidence of synergy between clothianidin and ELF EMFs as environmental stressors but suggest the potential for EMFs to affect the same susceptible fraction of the bee population that have been affected by clothianidin. Results lay the foundation to further explore the interactions of ELF EMFs with other environmental stressors and consider the key factors that may make bees susceptible to ELF EMFs.


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Microtubular structure impairment after GSM-modulated RF radiation exposure

Ana Marija Marjanović Čermak, Krunoslav Ilić, Ivan Pavičić. Microtubular structure impairment after GSM-modulated RF radiation exposure. Arh Hig Rada Toksikol. 2020 Oct 6;71(3):205-210. doi: 10.2478/aiht-2020-71-3267

Abstract

The objective of the study was to investigate whether low-level 915 MHz GSM-modulated radiofrequency (RF) radiation impairs microtubular structure and affects normal cell growth. V79 cells were exposed to a GSM-modulated field in a Gigahertz Transversal Electromagnetic Mode cell (GTEM cell) for 1, 2, and 3 h. Signal generator combined with power and chip modulator generated the electromagnetic field (EMF). The electric field strength was adjusted to 10, 20, and 30 V/m, and the average specific absorption rate (SAR) was calculated to be 0.23, 0.8, and 1.6 W/kg. The structure of microtubule proteins was assessed by indirect immunocytochemistry, and cell growth was determined based on cell counts taken every day over six post-exposure days. Three-hour radiation exposure significantly altered microtubule structure regardless of the electric field strength. Moreover, on the third post-exposure day, three-hour radiation significantly reduced cell growth, regardless of field strength. The same was observed with two-hour exposure at 20 and 30 V/m. In conclusion, 915 MHz GSM-modulated RF radiation affects microtubular proteins in a time-dependent manner, which, in turn, affects cell proliferation. Our future research will focus on microtubule structure throughout the cell cycle and RF radiation effects on mitotic spindle.


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Effects of Long-Term Exposure to L-Band ( ~2.0 GHz) High-Power (0.5, 1.0, and 1.5 W/m2) Microwave on the Brain Function of Male Mice

Lin Y, Gao P, Guo Y, Chen Q, Lang H, Guo Q, Miao X, Li J, Zeng L, Guo G. Effects of Long-Term Exposure to L-Band High-Power Microwave on the Brain Function of Male Mice. Biomed Res Int. 2021 Sep 4;2021:2237370. doi: 10.1155/2021/2237370.

Abstract

Currently, the impact of electromagnetic field (EMF) exposure on the nervous system is an increasingly arousing public concern. The present study was designed to explore the effects of continuous long-term exposure to L-band ( ~ 2.0 GHz) high-power microwave (L-HPM) on brain function and related mechanisms. Forty-eight male Institute of Cancer Research (ICR) mice were exposed to L-HPM at various power densities (0.5, 1.0, and 1.5 W/m2) and the brain function was examined at different time periods after exposure. The morphology of the brain was examined by hematoxylin-eosin (HE) and deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Furthermore, cholinergic markers, oxidative stress markers, and the expression of c-fos were evaluated to identify a "potential" mechanism. The results showed that exposure to L-HPM at 1.5 W/m2 can cause generalized injuries in the hippocampus (CA1 and CA3) and cerebral cortex (the first somatosensory cortex) of mice, including cell apoptosis, cholinergic dysfunction, and oxidative damage. Moreover, the deleterious effects were closely related to the power density and exposure time, indicating that long-term and high-power density exposure may be detrimental to the nervous system.


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Electromagnetic Pollution as a Possible Explanation for the Decline of House Sparrows in Interaction with Other Factors

Alfonso Balmori. Electromagnetic Pollution as a Possible Explanation for the Decline of House Sparrows in Interaction with Other Factors. Birds 2021, 2(3), 329-337; doi: 10.3390/birds2030024

Simple Summary

In recent decades, there has been a decline of the house sparrow (Passer domesticus), mainly in European cities, and several hypotheses have been proposed. The objective of this article is to delve into the reasons why an increase in electromagnetic radiation especially in cities, may be intervening in some way. Previous studies indicated that house sparrows were significantly negatively associated with increasing electromagnetic radiation and sparrows disappeared from areas most polluted. Electromagnetic radiation is the most plausible factor and is the only one that affects the other hypotheses proposed so far. Additionally, the recent sparrow decline matches the deployment of mobile telephony networks. For these reasons, electromagnetic radiation is not only a plausible but a probable hypothesis that must be seriously considered, probably in synergy with the other factors previously proposed.

Abstract

In recent decades, there has been a decline of the House Sparrow (Passer domesticus), mainly in European cities, and several hypotheses have been proposed that attempt to determine the causes of this rapid decline. Previous studies indicated that house sparrows were significantly negatively associated with increasing electromagnetic radiation and sparrows disappeared from areas most polluted. In addition, there are many studies on the impact of radiation on other bird and non-bird species, as well as numerous laboratory studies that demonstrated detrimental effects at electric field strength levels that can be found in cities today. Electromagnetic radiation is the most plausible factor for multiple reasons, including that this is the only one that affects the other hypotheses proposed so far. It is a type of pollution that affects productivity, fertility, decreases insects (chicken feed), causes loss of habitat, decreases immunity and can promote disease. Additionally, the recent sparrow decline matches the deployment of mobile telephony networks. Further, there are known mechanisms of action for non-thermal effects of electromagnetic radiation that may affect sparrows causing their decline. Thus, electromagnetic radiation must be seriously considered as a factor for house sparrows’ decline, probably in synergy with the other factors previously proposed.


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One-time Electromagnetic Irradiation Modifies Stress-sensitive Gene Expressions in Rice Plant


Ardhendu Kundu, Sathish Vangaru, Sucharita Bhowmick, Somnath Bhattacharyya, Amirul I Mallick, Bhaskar Gupta. One-time Electromagnetic Irradiation Modifies Stress-sensitive Gene Expressions in Rice Plant. Bioelectromagnetics. 2021 Sep 24. doi: 10.1002/bem.22374.

Abstract

Electromagnetic energy is utilized over multiple frequency bands to provide seamless wireless communication services. Plants can well perceive electromagnetic energy present in open environment due to reasonably high permittivity and electrical conductivity of constituent tissues. Moreover, higher surface-to-volume ratio of plant structure facilitates increased interaction with the incident electromagnetic waves. To date, a few well-designed studies have been conducted inside controlled electromagnetic reverberation chambers to investigate either short duration-low amplitude or long duration-periodic electromagnetic irradiation-induced molecular responses in plants. However, as far as is known, studies investigating molecular responses particularly at the mid-vegetative stage in plants following one-time (hours-long) electromagnetic irradiation have not been reported earlier. Hence, the present study aimed at investigating molecular responses in 40-day-old Swarnaprabha rice plants following one-time 1837.50 MHz, 2.75 mW/m2 electromagnetic irradiation of 2 h 30 min duration. Controlled electromagnetic irradiation inside a simple reverberation chamber was ensured to achieve pure electromagnetic environment at 1837.50 MHz with deterministic electromagnetic power density at selected position. Swarnaprabha rice plant was chosen for this investigation since the rice variety is widely cultivated and consumed in the Indian subcontinent. Subsequent alterations in some selected stress-sensitive gene expressions were assayed using real-time quantitative polymerase chain reaction technique-significant upregulation in calmodulin and phytochrome B gene expressions were noted. This investigation was purposefully focused on subsequent molecular responses immediately following electromagnetic irradiation so that the possible effects of secondary stimulations could be avoided. Observed molecular responses strongly suggested that plants perceive 1837.50 MHz, 2.75 mW/m2 electromagnetic irradiation similar to other injurious stimuli.

https://pubmed.ncbi.nlm.nih.gov/34559898/

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Short-Term Extremely Low-Frequency Electromagnetic Field Inhibits Synaptic Plasticity of Schaffer Collateral-CA1 Synapses in Rat Hippocampus via the Ca 2+/Calcineurin Pathway

Pei Xia, Yu Zheng, Lei Dong, Chunxiao Tian. Short-Term Extremely Low-Frequency Electromagnetic Field Inhibits Synaptic Plasticity of Schaffer Collateral-CA1 Synapses in Rat Hippocampus via the Ca 2+/Calcineurin Pathway. ACS Chem Neurosci. 2021 Sep 9. doi: 10.1021/acschemneuro.1c00500.

Abstract

In this study, we investigate the intrinsic mechanism by which an extremely low-frequency electromagnetic field (ELF-EMF) influences neurons in the Schaffer collateral-CA1 (SC-CA1) region of rat hippocampus using electrophysiological techniques. ELF-EMF has an interesting effect on synaptic plasticity: it weakens long-term potentiation and enhances long-term depression. Here, the magnetic field effect disappeared after a blockade of voltage-gated calcium channels and calcineurin, which are key components in the Ca2+/calcineurin pathway, with two blockers, cadmium chloride and cyclosporin A. This fully establishes that the effect of ELF-EMF on synaptic plasticity is mediated by the Ca2+/calcineurin pathway and represents a novel technique for studying the specific mechanisms of action of ELF-EMF on learning and memory.

https://pubmed.ncbi.nlm.nih.gov/34498467/

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DNMT1 and miRNAs: possible epigenetics footprints in electromagnetic fields utilization in oncology


Mohadeseh Shayeghan, Flora Forouzesh, Alireza Madjid Ansari, Mohammad Amin Javidi. DNMT1 and miRNAs: possible epigenetics footprints in electromagnetic fields utilization in oncology. Med Oncol. 2021 Sep 8;38(10):125. doi: 10.1007/s12032-021-01574-y.

Abstract

Many studies were performed to unravel the effects of different types of Electromagnetic fields (EMFs) on biological systems. Some studies were conducted to exploit EMFs for medical purposes mainly in cancer therapy. Although many studies suggest that the EMFs exposures can be effective in pre-clinical cancer issues, the treatment outcomes of these exposures on the cancer cells, especially at the molecular level, are challenging and overwhelmingly complicated yet. This article aims to review the epigenetic mechanisms that can be altered by EMFs exposures with the main emphasis on Extremely low frequency electromagnetic field (ELF-EMF). The epigenetic mechanisms are reversible and affected by environmental factors, thus, EMFs exposures can modulate these mechanisms. According to the reports, ELF-EMF exposures affect epigenetic machinery directly or through the molecular signaling pathways. ELF-EMF in association with DNA methylation, histone modification, miRNAs, and nucleosome remodeling could affect the homeostasis of cancer cells and play a role in DNA damage repairing, apoptosis induction, prevention of metastasis, differentiation, and cell cycle regulation. In general, the result of this study shows that ELF-EMF exposure probably can be effective in cancer epigenetic therapy, but more molecular and clinical investigations are needed to clarify the safe and specific dosimetric characteristics of ELF-EMF in practice.

https://pubmed.ncbi.nlm.nih.gov/34495398/

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Safety of Wireless Power Transfer

James C. Lin. Safety of Wireless Power Transfer. IEEE Access. 10 September 2021. doi: 10.1109/ACCESS.2021.3108966.

Abstract

Wireless power transfer (WPT) systems are developed to provide electric power either directly or via battery-charging. The optimism on WPT technology is driven by the ubiquity of cellphones, laptops, and mobile communication devices. Aside from not having to plug in a cellphone or laptop, WPT battery charging offers the potential for mobile devices to get electrical power the same way they get data through harvesting ambient electromagnetic radiation. The dream is a truly wireless mobility scenario with tether-free electric power for cellphones, laptops, appliances, and transportation systems. Beyond wireless communication, the electromagnetic power required for large-scale commercial WPT implementation is substantial. A key facet of the system design and research should include consideration of health effects and safety of radiofrequency electromagnetic radiation.


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Cellular effects of terahertz waves

Cherkasova OP, Serdyukov DS, Nemova EF, Ratushnyak AS, Kucheryavenko AS, Dolganova IN, Xu G, Skorobogatiy M, Reshetov IV, Timashev PS, Spektor IE, Zaytsev KI, Tuchin VV. Cellular effects of terahertz waves. J Biomed Opt. 2021 Sep;26(9). doi: 10.1117/1.JBO.26.9.090902.

Abstract

Significance: An increasing interest in the area of biological effects at exposure of tissues and cells to the terahertz (THz) radiation is driven by a rapid progress in THz biophotonics, observed during the past decades. Despite the attractiveness of THz technology for medical diagnosis and therapy, there is still quite limited knowledge about safe limits of THz exposure. Different modes of THz exposure of tissues and cells, including continuous-wave versus pulsed radiation, various powers, and number and duration of exposure cycles, ought to be systematically studied.

Aim: We provide an overview of recent research results in the area of biological effects at exposure of tissues and cells to THz waves.

Approach: We start with a brief overview of general features of the THz-wave-tissue interactions, as well as modern THz emitters, with an emphasis on those that are reliable for studying the biological effects of THz waves. Then, we consider three levels of biological system organization, at which the exposure effects are considered: (i) solutions of biological molecules; (ii) cultures of cells, individual cells, and cell structures; and (iii) entire organs or organisms; special attention is devoted to the cellular level. We distinguish thermal and nonthermal mechanisms of THz-wave-cell interactions and discuss a problem of adequate estimation of the THz biological effects' specificity. The problem of experimental data reproducibility, caused by rareness of the THz experimental setups and an absence of unitary protocols, is also considered.

Results: The summarized data demonstrate the current stage of the research activity and knowledge about the THz exposure on living objects.

Conclusions: This review helps the biomedical optics community to summarize up-to-date knowledge in the area of cell exposure to THz radiation, and paves the ways for the development of THz safety standards and THz therapeutic applications.

Conclusion

Recent research results in the area of THz-wave effects on biological systems of the different organization levels, such as biomolecules, cells, and organism, were discussed. Despite the considerable data accumulated in this demanding research direction, we still possess quite limited knowledge about biological effects of THz waves. Further research and engineering efforts are required to develop adequate safe limits of THz-wave exposure and to objectively uncover strengths and weaknesses of THz technology in different branches of medial therapy. Thus, this review summarizes up-to-date knowledge in the area of cell exposure to THz radiation and paves the ways to the THz dosimetry and therapeutic avenues.


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Numerical modelling and experimental verification of thermal effects in living cells exposed to high-power pulses of THz (terahertz) radiation

D S Sitnikov, A A Pronkin, I V Ilina, V A Revkova, M A Konoplyannikov, V A Kalsin, V P Baklaushev. Numerical modelling and experimental verification of thermal effects in living cells exposed to high-power pulses of THz radiation. Sci Rep. 2021 Sep 9;11(1):17916. doi: 10.1038/s41598-021-96898-0.

Abstract

Exposure of cells or biological tissues to high-power pulses of terahertz (THz) radiation leads to changes in a variety of intracellular processes. However, the role of heating effects due to strong absorption of THz radiation by water molecules still stays unclear. In this study, we performed numerical modelling in order to estimate the thermal impact on water of a single THz pulse as well as a series of THz pulses. A finite-element (FE) model that provides numerical solutions for the heat conduction equation is employed to compute the temperature increase. A simple expression for temperature estimation in the center of the spot of THz radiation is presented for given frequency and fluence of the THz pulse. It has been demonstrated that thermal effect is determined by either the average power of radiation or by the fluence of a single THz pulse depending on pulse repetition rate. Human dermal fibroblasts have been exposed to THz pulses (with an energy of [Formula: see text] and repetition rate of 100 Hz) to estimate the thermal effect. Analysis of heat shock proteins expression has demonstrated no statistically significant difference ([Formula: see text]) between control and experimental groups after 3 h of irradiation.

Open access paper: https://www.nature.com/articles/s41598-021-96898-0

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Electric field detection as floral cue in hoverfly pollination

Khan SA, Khan KA, Kubik S, Ahmad S, Ghramh HA, Ahmad A, Skalicky M, Naveed Z, Malik S, Khalofah A, Aljedani DM. Electric field detection as floral cue in hoverfly pollination. Sci Rep. 2021 Sep 21;11(1):18781. doi: 10.1038/s41598-021-98371-4.

Abstract

Pollinators can detect the color, shape, scent, and even temperature of the flowers they want to visit. Here, we present the previously unappreciated capacity of hoverflies (Eristalis tenax and Cheilosia albipila) to detect the electric field surrounding flowers. Using hoverflies as key dipteran pollinators, we explored the electrical interactions between flies and flowers-how a hoverfly acquired a charge and how their electrical sensing ability for target flowers contributed to nectar identification and pollination. This study revealed that rapid variations in a floral electric field were related to a nectar reward and increased the likelihood of the fly's return visits. We found that thoracic hairs played a role in the polarity of hoverfly charge, revealing their electro-mechanosensory capability, as in bumblebees (Bombus terrestris). Electrophysiological analysis of the hoverfly's antennae did not reveal neural sensitivity to the electric field, which favors the mechanosensory hairs as putative electroreceptive organs in both species of hoverflies.