Oxidative stress response in SH-SY5Y cells exposed to short-term 1800 MHz radiofrequency radiation

Early-life exposure to PCBs and PFAS exerts negative effects on the developing central nervous system

Persistent organic pollutants (POPs) are ubiquitous in the environment and display the capacity to bioaccumulate in living organisms, constituting a hazard to both wildlife and humans. Although restrictions have been applied to prohibit the production of several POPs since the 1960s, high levels of these compounds can still be detected in many environmental and biological matrices, due to their chemical properties and significantly long half-lives. Some POPs can be passed from mother to the fetus and can gain entry to the central nervous system (CNS), by crossing the blood-brain barrier (BBB), resulting in significant deleterious effects, including neurocognitive and psychiatric abnormalities, which may lead to long-term socio-economic burdens. A growing body of evidence obtained from clinical and experimental studies has increasingly indicated that these POPs may influence neurodevelopment through several cellular and molecular mechanisms. However, studies assessing their mechanisms of action are still incipient, requiring further research. Polychlorinated biphenyls (PCBs) and per- and polyfluoroalkyl substances (PFAS) are two of the main classes of POPs associated with disturbances in different human systems, mainly the nervous and endocrine systems. This narrative review discusses the main PCB and PFAS effects on the CNS, focusing on neuroinflammation and oxidative stress and their consequences for neural development and BBB integrity. Moreover, we propose which mechanisms could be involved in POP-induced neurodevelopmental defects. In this sense, we highlight potential cellular and molecular pathways by which these POPs can affect neurodevelopment and could be further explored to propose preventive therapies and formulate public health policies.

Gaps in Knowledge Relevant to the "ICNIRP Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic and Electromagnetic Fields (100 kHz TO 300 GHz)"

ABSTRACT

In the last 30 y, observational as well as experimental studies have addressed possible health effects of exposure to radiofrequency electromagnetic fields (EMF) and investigated potential interaction mechanisms. The main goal of ICNIRP is to protect people and the environment from detrimental exposure to all forms of non-ionizing radiation (NIR), providing advice and guidance by developing and disseminating exposure guidelines based on the available scientific research on specific parts of the electromagnetic spectrum. During the development of International Commission on Non-Ionizing Radiation Protection's (ICNIRP's) 2020 radiofrequency EMF guidelines some gaps in the available data were identified. To encourage further research into knowledge gaps in research that would, if addressed, assist ICNIRP in further developing guidelines and setting revised recommendations on limiting exposure, data gaps that were identified during the development of the 2020 radiofrequency EMF guidelines, in conjunction with subsequent consideration of the literature, are described in this Statement. Note that this process and resultant recommendations were not intended to duplicate more traditional research agendas, whose focus is on extending knowledge in this area more generally but was tightly focused on identifying the highest data gap priorities for guidelines development more specifically. The result of this distinction is that the present data gap recommendations do not include some gaps in the literature that in principle could be relevant to radiofrequency EMF health, but which were excluded because either the link between exposure and endpoint, or the link between endpoint and health, was not supported sufficiently by the literature. The evaluation of these research areas identified the following data gaps: (1) Issues concerning relations between radiofrequency EMF exposure and heat-induced pain; (2) Clarification of the relation between whole-body exposure and core temperature rise from 100 kHz to 300 GHz, as a function of exposure duration and combined EMF exposures; (3) Adverse effect thresholds and thermal dosimetry for a range of ocular structures; (4) Pain thresholds for contact currents under a range of exposure scenarios, including associated dosimetry; and (5) A range of additional dosimetry studies to both support future research, and also to improve the application of radiofrequency EMF exposure restrictions in future guidelines.

The effects of radiofrequency electromagnetic field exposure on biomarkers of oxidative stress in vivo and in vitro: A systematic review of experimental studies

BACKGROUND

Oxidative stress is thought to be related to many diseases. Furthermore, it is hypothesized that radiofrequency electromagnetic fields (RF-EMF) may induce excessive oxidative stress in various cell types and thereby have the potential to compromise human and animal health. The objective of this systematic review (SR) is to summarize and evaluate the literature on the relation between the exposure to RF-EMF in the frequency range from 100 kHz to 300 GHz and biomarkers of oxidative stress.

METHODS

The SR framework was developed following the guidelines established in the WHO Handbook for Guideline Development and NTP/OHAT's Handbook for Conducting a Literature-Based Health Assessment. We used the latter handbook's methodology for implementing the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach for environmental health assessments. We searched the following databases up until June 30, 2023: PubMed, Embase, Web of Science Core Collection, Scopus, and the EMF-Portal. The reference lists of included studies and retrieved review articles were also manually searched. We rated Risk of Bias (RoB) using the OHAT RoB Rating Tool and assessed publication bias using funnel plots of included studies. We assessed the certainty of the evidence (high, moderate, low, or very low) for an association between RF-EMF and oxidative stress using an adapted version of the GRADE framework. Data were extracted according to a predefined set of forms developed in DistillerSR. Data were analysed after grouping them first as in vitro or in vivo and then according to outcome category, species category, and exposed tissue. We synthesized study results using a random effects meta-analysis when study characteristics were judged sufficiently similar to be combined and heterogeneity (I2) was lower than 75 %, otherwise we describe the findings narratively.

RESULTS

Fifty-six (56) studies, 45 in vivo and 11 in vitro, in which cells (in vitro) or animals (in vivo) were exposed to frequencies in the range 800-2450 MHz, were included in the systematic review after eliminating 12,353 publications because they did not meet the criteria defined in the published protocol (Henschenmacher et al., 2022). Of 56 studies 52 studies with 169 individual results were included in the meta-analysis. Together, these studies examined six human in vitro samples and fifty animal samples, including rodents (mice, rats, hamsters, and guinea pigs, (n = 46)) and rabbits (n = 4). RF-EMF were predominantly applied as continuous wave exposures in these studies. The outcome biomarkers for modified proteins and amino acids were measured in n = 30 studies, for oxidized DNA bases in n = 26 studies, for oxidized lipids in n = 3 studies and hydrogen peroxide production in 2 studies. Outcomes were mostly measured in the brain (n = 22), liver (n = 9), cells (n = 9), blood (n = 6), and testis (n = 2). RoB in studies was high, mainly due to biases in exposure and outcome assessment.

IN VIVO STUDIES

Brain: The effect on biomarkers for oxidized DNA bases in the rodent brain (five studies, n = 98) had an inconsistent effect, varying from a large decrease with a standardized mean difference (SMD) of -3.40 (95 % CI [-5.15, -1.64]) to a large increase with an SMD of 2.2 (95 % CI [0.78, 3.62]). In the brain of rabbits (two studies, n = 44), the effect sizes also varied, from an SMD of -1.06 (95 % CI [-2.13, 0.00]) to an SMD of 5.94 (95 % CI [3.14, 8.73]). The effect on biomarkers for modified proteins and amino acids in the rodent brain (15 studies, n = 328) also varied from a large decrease with an SMD of -6.11 (95 % CI [-8.16, -4.06]) to a large increase with an SMD of 5.33 (95 % CI [2.49, 8.17]). The effect on biomarkers for oxidized lipids in the brain of rodents (one study, n = 56) also varied from a large decrease with SMD = -4.10 (95 % CI [-5.48, -2.73]) to SMD = 1.27 (95 % CI [0.45, 2.10]). Liver: The effect on biomarkers for oxidized DNA bases in the rodent liver (two studies, n = 26) was inconsistent with effect sizes in both directions: SMD = -0.71 (95 % CI [-1.80, 0.38]) and SMD = 1.56 (95 % CI [0.19, 2.92]). The effect on biomarkers for oxidized DNA bases in the rabbits' liver (two studies, n = 60) was medium with a pooled SMD of 0.39 (95 % CI [-0.79, 1.56]). Biomarkers for modified proteins and amino acids in the liver of rodents (six studies, n = 159) increased with a pooled SMD of 0.55 (95 % CI [0.06, 1.05]). Blood: The effect of RF-EMF on biomarkers for oxidized DNA bases in rodent blood (four studies, n = 104) was inconsistent, with SMDs ranging from -1.14 (95 % CI [-2.23, -0.06]) to 1.71 (95 % CI [-0.10, 3.53]). RF-EMF had no effect on biomarkers for modified proteins and amino acids in rodent blood (three studies, n = 40), with a pooled SMD of -0.08 (95 % CI [-1.32, 1.16]). There was a large increase in biomarkers for oxidized DNA bases in rodent plasma (two studies, n = 38) with a pooled SMD of 2.25 (95 % CI [1.27, 3.24]). Gonads: There was an increase in biomarkers for oxidized DNA bases in the rodent testis (two studies, n = 24) with a pooled SMD of 1.60 (95 % CI [0.62, 2.59]). The effect of RF-EMF on biomarkers for modified proteins and amino acids in the ovary of rodents (two studies, n = 52) was inconsistent with a medium effect, SMD = 0.24 (95 % CI [-0.74, 1.23])) and a large effect (SMD = 2.08 (95 % CI [1.22, 2.94])). Thymus: RF-EMF increased biomarkers for modified proteins and amino acids in the thymus of rodents (one study, n = 42) considerably with a pooled SMD of 6.16 (95 % CI [3.55, 8.76]). Cells: RF-EMF increased oxidized DNA bases in rodent cells with SMD of 2.49 (95 % CI [1.30, 3.67]) (one study, n = 27). There was a medium effect in oxidized lipids (one study, n = 18) but not statistically significant with SMD = 0.34 (95 % CI [-0.62, 1.29]).

IN VITRO STUDIES

In in vitro studies in human cells (three studies, n = 110), there were inconsistent increases in biomarkers for oxidized DNA bases, where the SMDs varied between 0.01 (95 % CI [-0.59, 0.62]) and 7.12 (95% CI [0.06, 14.18]) in 4 results (2 of them statistically significant). In rodent cells (three studies, n = 24), there was a not statistically significant large effect in biomarkers for oxidized DNA bases with SMD = 2.07 (95 % CI [-1.38, 5.52]). The RF-EMF biomarkers for modified proteins and amino acids in human cells (one study, n = 18) showed a large effect with SMD = 1.07 (95 % CI [-0.05, 2.19]). In rodent cells (two studies, n = 24) a medium effect of SMD = 0.56 (95 % CI [-0.29, 1.41]) was observed.

DISCUSSION

The evidence on the relation between the exposure to RF-EMF and biomarkers of oxidative stress was of very low certainty, because a majority of the included studies were rated with a high RoB level and provided high heterogeneity. This is due to inaccurate measurements of exposure and/or of measurement of oxidative stress biomarkers and missing information on the blinding of research personnel to exposure conditions or outcome measurements. There may be no or an inconsistent effect of RF-EMF on biomarkers of oxidative stress in the brain, liver, blood, plasma and serum, and in the female reproductive system in animal experiments but the evidence is of very low certainty. There may be an increase in biomarkers of oxidative stress in testes, serum and thymus of rodents but the evidence is of very low certainty. Future studies should improve experimental designs and characterization of exposure systems as well as the use of validated biomarker measurements with positive controls. Other: This review was partially funded by the World Health Organization. The protocol for this review is registered in PROSPERO (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021235573) and published in Environment International (https://doi.org/10.1016/j.envint.2021.106932) (Henschenmacher et al., 2022).

The Exposure to 2.45 GHz Electromagnetic Radiation Induced Different Cell Responses in Neuron-like Cells and Peripheral Blood Mononuclear Cells

Electromagnetic radiation emitted by commonly used devices became an issue for public health because of their harmful effects. Notably, 2.45 GHz electromagnetic radiation exposure has been associated with DNA damage and alterations in the central nervous system. We here investigated the effects of 2.45 GHz electromagnetic radiation on cell redox status by using human SH-SY5Y neuroblastoma cells, which were differentiated to neuronal-like cells, and peripheral blood mononuclear cells (PBMCs), which were exposed to an antenna emitting 2.45 GHz electromagnetic radiation for 2, 24, and 48 h. We evaluated cell viability and mitochondrial activity alterations by measuring reactive oxygen species (ROS), mitochondrial transmembrane potential (ΔΨm), NAD+/NADH ratio, mitochondrial transcription factor A (mtTFA), and superoxide dismutase 1 (SOD1) gene transcript levels. We also investigated apoptosis and autophagy, evaluating B-cell lymphoma 2 (BCL2), BCL2-associated X protein (BAX), and microtubule-associated protein 1A/1B-light chain 3 (LC3) gene transcript levels. Cell viability was significantly reduced after 24-48 h of exposure to radiation. ROS levels significantly increased in radiation-exposed cells, compared with controls at all exposure times. ΔΨm values decreased after 2 and 24 h in exposed SH-SY5Y cells, while in PBMCs, values decreased soon after 2 h of exposure. Alterations were also found in the NAD+/NADH ratio, mtTFA, SOD1, LC3 gene expression, and BAX/BCL2 ratio. Our results showed that neuron-like cells are more prone to developing oxidative stress than PBMCs after 2.45 GHz electromagnetic radiation exposure, activating an early antioxidant defense response.

Evaluation of DNA Methylation Profiles of LINE-1, Alu and Ribosomal DNA Repeats in Human Cell Lines Exposed to Radiofrequency Radiation

A large body of evidence indicates that environmental agents can induce alterations in DNA methylation (DNAm) profiles. Radiofrequency electromagnetic fields (RF-EMFs) are radiations emitted by everyday devices, which have been classified as "possibly carcinogenic"; however, their biological effects are unclear. As aberrant DNAm of genomic repetitive elements (REs) may promote genomic instability, here, we sought to determine whether exposure to RF-EMFs could affect DNAm of different classes of REs, such as long interspersed nuclear elements-1 (LINE-1), Alu short interspersed nuclear elements and ribosomal repeats. To this purpose, we analysed DNAm profiles of cervical cancer and neuroblastoma cell lines (HeLa, BE(2)C and SH-SY5Y) exposed to 900 MHz GSM-modulated RF-EMF through an Illumina-based targeted deep bisulfite sequencing approach. Our findings showed that radiofrequency exposure did not affect the DNAm of Alu elements in any of the cell lines analysed. Conversely, it influenced DNAm of LINE-1 and ribosomal repeats in terms of both average profiles and organisation of methylated and unmethylated CpG sites, in different ways in each of the three cell lines studied.

Non-thermal disruption of β-adrenergic receptor-activated Ca2+ signalling and apoptosis in human ES-derived cardiomyocytes by microwave electric fields at 2.4 GHz

The ubiquity of wireless electronic-device connectivity has seen microwaves emerge as one of the fastest growing forms of electromagnetic exposure. A growing evidence-base refutes the claim that wireless technologies pose no risk to human health at current safety levels designed to limit thermal (heating) effects. The potential impact of non-thermal effects of microwave exposure, especially in electrically-excitable tissues (e.g., heart), remains controversial. We exposed human embryonic stem-cell derived cardiomyocytes (CM), under baseline and beta-adrenergic receptor (β-AR)-stimulated conditions, to microwaves at 2.4 GHz, a frequency used extensively in wireless communication (e.g., 4G, Bluetooth™ and WiFi). To control for any effect of sample heating, experiments were done in CM subjected to matched rates of direct heating or CM maintained at 37 °C. Detailed profiling of the temporal and amplitude features of Ca²⁺ signalling in CM under these experimental conditions was reconciled with the extent and spatial clustering of apoptosis. The data show that exposure of CM to 2.4 GHz EMF eliminated the normal Ca²⁺ signalling response to β-AR stimulation and provoked spatially-clustered apoptosis. This is first evidence that non-thermal effects of 2.4 GHz microwaves might have profound effects on human CM function, responsiveness to activation, and survival.

Label-Free Study of the Global Cell Behavior during Exposure to Environmental Radiofrequency Fields in the Presence or Absence of Pro-Apoptotic or Pro-Autophagic Treatments

It remains controversial whether exposure to environmental radiofrequency signals (RF) impacts cell status or response to cellular stress such as apoptosis or autophagy. We used two label-free techniques, cellular impedancemetry and Digital Holographic Microscopy (DHM), to assess the overall cellular response during RF exposure alone, or during co-exposure to RF and chemical treatments known to induce either apoptosis or autophagy. Two human cell lines (SH-SY5Y and HCT116) and two cultures of primary rat cortex cells (astrocytes and co-culture of neurons and glial cells) were exposed to RF using an 1800 MHz carrier wave modulated with various environmental signals (GSM: Global System for Mobile Communications, 2G signal), UMTS (Universal Mobile Telecommunications System, 3G signal), LTE (Long-Term Evolution, 4G signal, and Wi-Fi) or unmodulated RF (continuous wave, CW). The specific absorption rates (S.A.R.) used were 1.5 and 6 W/kg during DHM experiments and ranged from 5 to 24 W/kg during the recording of cellular impedance. Cells were continuously exposed for three to five consecutive days while the temporal phenotypic signature of cells behavior was recorded at constant temperature. Statistical analysis of the results does not indicate that RF-EMF exposure impacted the global behavior of healthy, apoptotic, or autophagic cells, even at S.A.R. levels higher than the guidelines, provided that the temperature was kept constant.

Threshold of radiofrequency electromagnetic field effect on human brain

PURPOSE

This review aims to estimate the threshold of radiofrequency electromagnetic field (RF EMF) effects on human brain based on analyses of published research results. To clarify the threshold of the RF EMF effects, two approaches have been applied: (1) the analyses of restrictions in sensitivity for different steps of the physical model of low-level RF EMF mechanism and (2) the analyses of experimental data to clarify the dependence of the RF EMF effect on exposure level based on the results of published original neurophysiological and behavioral human studies for 15 years 2007-2021.

CONCLUSIONS

The analyses of the physical model of nonthermal mechanisms of RF EMF effect leads to conclusion that no principal threshold of the effect can be determined. According to the review of experimental data, the rate of detected RF EMF effects is 76.7% in resting EEG studies, 41.7% in sleep EEG and 38.5% in behavioral studies. The changes in EEG probably appear earlier than alterations in behavior become evident. The lowest level of RF EMF at which the effect in EEG was detected is 2.45 V/m (SAR = 0.003 W/kg). There is a preliminary indication that the dependence of the effect on the level of exposure follows rather field strength than SAR alterations. However, no sufficient data are available for clarifying linearity-nonlinearity of the dependence of effect on the level of RF EMF. The finding that only part of people are sensitive to RF EMF exposure can be related to immunity to radiation or hypersensitivity. The changes in EEG caused by RF EMF appeared similar in the majority of analyzed studies and similar to these in depression. The possible causal relationship between RF EMF effect and depression among young people is highly important problem.

Effects of 1800 MHz radiofrequency fields on signal transduction and antioxidant proteins in human A172 glioblastoma cells

PURPOSE

To assess the effects of 1800 MHz radiofrequency electromagnetic field (RF-EMF) exposure on the expression of signal transduction and antioxidant proteins in a human-derived A172 glioblastoma cell line.

MATERIALS AND METHODS

Adherent human-derived A172 glioblastoma cells (1.0 × 105 cells per 35 mm culture dish, containing 2 mL DMEM media) were exposed to 1800 MHz continuous-wave (CW) or GSM-modulated RF fields, in the presence or absence of serum for 5, 30 or 240 min at a specific absorption rate (SAR) of 0 (sham) or 2.0 W/kg. Concurrent negative (vehicle) and positive controls (1 µg/mL anisomycin) were included in each experiment. Cell lysates were collected immediately after exposure, stabilized by protease and phosphatase inhibitors in lysis buffer, then frozen and maintained at -80 °C until analysis. The relative expression levels of phosphorylated- and total-signal transduction proteins (CREB, JNK, NF-κB, ERK1/2, Akt, p70S6K, STAT3 and STAT5) and antioxidant proteins (SOD1, SOD2, CAT, TRX1, PRX2) were assessed using Milliplex magnetic bead array panels and a MagPix Multiplex imaging system.

RESULTS

In cells exposed to 1800 MHz continuous-wave RF-EMF with the presence of serum in the culture medium, CAT expression was statistically significantly decreased after a 30 min exposure, total JNK was decreased at both 30 and 240 min of exposure, STAT3 was decreased after 240 min of exposure and phosphorylated-CREB expression was decreased after 30 min of exposure. In cells exposed to 1800 MHz GSM-modulated RF-EMF in serum-free cultures, the expression level of total STAT5 was decreased after 30 and 240 min of exposure. These observed changes were detected sporadically across time-points, culture conditions and RF-EMF exposure conditions indicating the likelihood of false positive events. When cells were treated with anisomycin for 15 min as a positive control, dramatic increases in the expression of phosphorylated signaling proteins were observed in both serum-starved and serum-fed A172 cells, with larger fold change increases in the serum-free cultures. No statistically significant differences in the expression levels of SOD1, SOD2 or TRX1 were observed under any tested conditions after exposure to RF-EMF.

CONCLUSIONS

The current study found no consistent evidence of changes in the expression of antioxidant proteins (SOD1, SOD2, CAT or TRX2) or a variety of signal transductions proteins (CREB, JNK, NF-κB, ERK1/2, Akt, p70S6K, STAT3, STAT5) in a human-derived glioblastoma A172 cell line in response to exposure to 1800 MHz continuous-wave or GSM-modulated RF-EMF for 5, 30 or 240 min in either serum-free or serum-containing cultures.

Manmade Electromagnetic Fields and Oxidative Stress-Biological Effects and Consequences for Health

Concomitant with the ever-expanding use of electrical appliances and mobile communication systems, public and occupational exposure to electromagnetic fields (EMF) in the extremely-low-frequency and radiofrequency range has become a widely debated environmental risk factor for health. Radiofrequency (RF) EMF and extremely-low-frequency (ELF) MF have been classified as possibly carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer (IARC). The production of reactive oxygen species (ROS), potentially leading to cellular or systemic oxidative stress, was frequently found to be influenced by EMF exposure in animals and cells. In this review, we summarize key experimental findings on oxidative stress related to EMF exposure from animal and cell studies of the last decade. The observations are discussed in the context of molecular mechanisms and functionalities relevant to health such as neurological function, genome stability, immune response, and reproduction. Most animal and many cell studies showed increased oxidative stress caused by RF-EMF and ELF-MF. In order to estimate the risk for human health by manmade exposure, experimental studies in humans and epidemiological studies need to be considered as well.

Effects of Environment and Lifestyle Factors on Anovulatory Disorder

Anovulatory disorder comprises around 30% of female infertility. The origin of ovulatory failure is rooted in pituitary FSH secretion. Any factor or process that disrupts the finely tuned interactions of hypothalamo-pituitary-ovarian axis can potentially lead to anovulation. The World Health Organization (WHO) has classified anovulatory disorders into three categories: hypothalamic-pituitary failure, hypothalamic-pituitary dysregulation, and ovarian failure. Due to industrial development, environmental pollution, and global warming, the human living environment has undergone tremendous changes. Industrial waste, noise, pesticides, fertilizers, and vehicular emission are visible pollutants responsible for environmental contamination and ill effects on health of all living systems. A considerable body of research suggests that chemical exposures in the environment or workplace may be associated with endocrine disruption of the synthesis, secretion, transport, binding, or elimination of natural hormones. For instance, some advanced biological mechanisms suggest that heavy metals may affect progesterone production, which possibly disturbs endocrine function in pregnant women. On the other hand, our lifestyle factors have also changed accordingly, which greatly influence overall health and well-being, including fertility. Many lifestyle factors such as nutrition, weight, exercise, and psychological stress can have substantial effects on female ovulation.

Impact of Cerebral Radiofrequency Exposures on Oxidative Stress and Corticosterone in a Rat Model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is the most common type of neurodegenerative disease leading to dementia. Several studies suggested that mobile phone radiofrequency electromagnetic field (RF-EMF) exposures modified AD memory deficits in rodent models.

OBJECTIVE

Here we aimed to test the hypothesis that RF-EMF exposure may modify memory through corticosterone and oxidative stress in the Samaritan rat model of AD.

METHODS

Long-Evans male rats received intracerebroventricular infusion with ferrous sulphate, amyloid-beta 1-42 peptide, and buthionine-sufloximine (AD rats) or with vehicle (control rats). To mimic cell phone use, RF-EMF were exposed to the head for 1 month (5 days/week, in restraint). To look for hazard thresholds, high brain averaged specific absorption rates (BASAR) were tested: 1.5 W/Kg (15 min), 6 W/Kg (15 min), and 6 W/Kg (45 min). The sham group was in restraint for 45 min. Endpoints were spatial memory in the radial maze, plasmatic corticosterone, heme oxygenase-1 (HO1), and amyloid plaques.

RESULTS

Results indicated similar corticosterone levels but impaired memory performances and increased cerebral staining of thioflavine and of HO1 in the sham AD rats compared to the controls. A correlative increase of cortical HO1 staining was the only effect of RF-EMF in control rats. In AD rats, RF-EMF exposures induced a correlative increase of hippocampal HO1 staining and reduced corticosterone.

DISCUSSION

According to our data, neither AD nor control rats showed modified memory after RF-EMF exposures. Unlike control rats, AD rats showed higher hippocampal oxidative stress and reduced corticosterone with the higher BASAR. This data suggests more fragility related to neurodegenerative disease toward RF-EMF exposures.

The effects of acute and chronic exposure to 900 MHz radiofrequency radiation on auditory brainstem response in adult rats

The aim of this study was to determine the effects of short and long-term RFR exposure on ABR by evaluating lipid peroxidation and antioxidant status in adult rats. Sixty male albino Wistar rats were randomly divided into four groups. S1:1 week sham, S10:10 weeks sham, E1:1 week RFR, E10:10 weeks RFR. Experimental group rats were exposed to RFR 2 h/day, 5 days/week during the test period. Sham rats were kept in the same conditions without RFR. After the experiment, ABRs were recorded from the mastoids of rats using tone burst acoustic stimuli. Biochemical investigations in rat brain and ultrastructural analysis in temporal cortex were performed. ABR wave I latency prolonged in E1-group and shortened in E10-group compared to their shams. TBARS level increased in E1-group, decreased in E10-group, on the contrary, SOD and CAT activities and GSH level decreased in E1-group, increased in E10-group compared to their sham groups. Edema was present in the neuron and astrocyte cytoplasms and astrocyte end-feet in both E1 and E10 groups. Our results suggest that 900 MHz RFR may have negative effects on the auditory system in acute exposure and no adverse effects in chronic exposure without weekends.

Microtubular structure impairment after GSM-modulated RF radiation exposure

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.

Effects of pulse-modulated radiofrequency magnetic field (RF-EMF) exposure on apoptosis, autophagy, oxidative stress and electron chain transport function in human neuroblastoma and murine microglial cells

The use of body-worn wireless devices with different communication protocols and rapidly changing exposure scenarios is still multiplying and the need to identify possible health effects of radiofrequency electromagnetic field (RF-EMF) exposure with extremely low-frequency (ELF) modulation envelops. In this study, effects of ELF-modulated 935 MHz RF-EMF on apoptosis, autophagy, oxidative stress and electron exchange in N9 microglial and SH-SY5Y neuroblastoma cells were investigated. Cells were exposed at 4 W/kg or sham-exposed for 2 and 24 h. RF-EMF exposure of both cell types did not alter apoptosis, the number of living cells nor the apoptosis-inducing factor (AIF), irrespective of the exposure duration. RF-EMF exposure for 24, but not for 2 h, increased protein levels of the autophagy marker ATG5, whereas LC3B-I and II and pERK were not altered in both cell types and exposure times investigated. A transient increase in glutathione (GSH), but not hydrogen peroxide and cytochrome c oxidase was found only in SH-SY5Y cells, indicating that short-time RF-EMF at SAR levels accepted by today's safety guidelines might cause autophagy and oxidative stress with the effect being dependent on cell type and exposure duration. Further studies are needed to evaluate possible underlying mechanisms involved in pulse-modulated RF-EMF exposure.

Plant-Derived Natural Biomolecule Picein Attenuates Menadione Induced Oxidative Stress on Neuroblastoma Cell Mitochondria

Several bioactive compounds are in use for the treatment of neurodegenerative disorders, such as Alzheimer’s and Parkinson’s disease. Historically, willow (salix sp.) bark has been an important source of salisylic acid and other natural compounds with anti-inflammatory, antipyretic and analgesic properties. Among these, picein isolated from hot water extract of willow bark, has been found to act as a natural secondary metabolite antioxidant. The aim of this study was to investigate the unrevealed pharmacological action of picein. In silico studies were utilized to direct the investigation towards the neuroprotection abilities of picein. Our in vitro studies demonstrate the neuroprotective properties of picein by blocking the oxidative stress effects, induced by free radical generator 2-methyl-1,4-naphthoquinone (menadione, MQ), in neuroblastoma SH-SY5Y cells. Several oxidative stress-related parameters were evaluated to measure the protection for mitochondrial integrity, such as mitochondrial superoxide production, mitochondrial activity (MTT), reactive oxygen species (ROS) and live-cell imaging. A significant increase in the ROS level and mitochondrial superoxide production were measured after MQ treatment, however, a subsequent treatment with picein was able to mitigate this effect by decreasing their levels. Additionally, the mitochondrial activity was significantly decreased by MQ exposure, but a follow-up treatment with picein recovered the normal metabolic activity. In conclusion, the presented results demonstrate that picein can significantly reduce the level of MQ-induced oxidative stress on mitochondria, and thereby plays a role as a potent neuroprotectant.

Superior protective effects of in vitro propagated green garlic against hydrogen peroxide-induced cytotoxicity in human hepatoma cells

Garlic is a valuable source material for medicines due to its known antitumor, hypolipidaemic, antioxidant, and immunomodulatory effects. This study compares the protective effects of conventionally grown (CG) and in vitro propagated garlic (PG) against hydrogen peroxide-induced cytotoxicity in HepG2 cells and their antioxidant activity. Garlic used in this study was obtained by planting garlic cloves or by planting the transplants of PG directly in the field. At the end of the vegetation period, CG and PG were sampled and extracts prepared for the experiment. Compared to conventionally grown garlic bulbs, PG leafy part yielded significantly higher content of polyphenols, flavonoids and alliin, and also showed equal or higher antioxidant activity, measured by the cell viability test, GSH and ROS level. Moreover, PG can be produced in less time (shorter vegetation period) and with significantly less material (cloves). Significantly higher content of alliin, polyphenols, and flavonoids and significantly higher yield of plant biomass in PG has a great potential to become a new production model with improved garlic properties as a medicine material.

A comprehensive review on recent developments of radio frequency treatment for pasteurizing agricultural products

Recent pathogen incidents have forced food industry to seek for alternative processes in postharvest pasteurization of agricultural commodities. Radio frequency (RF) heating has been used as one alternative treatment to replace chemical fumigation and other conventional thermal methods since it is relatively easy to apply and leaves no chemical residues. RF technology transfers electromagnetic energy into large bulk volume of the products to provide a fast and volumetric heating. There are two types of RF technology commonly applied in lab and industry to generate the heat energy: free running oscillator and 50-Ω systems. Several reviews have been published to introduce the application of RF heating in food processing. However, few reviews have a comprehensive summary of RF treatment for pasteurizing agricultural products. The objective of this review was to introduce the developments in the RF pasteurization of agricultural commodities and to present future directions of the RF heating applications. While the recent developments in the RF pasteurization were presented, thermal death kinetics of targeted pathogens as influenced by water activity, pathogen species and heating rates, non-thermal effects of RF heating, combining RF heating with other technologies for pasteurization, RF heating uniformity improvements using computer simulation and development of practical RF pasteurization processes were also focused. This review is expected to provide a comprehensive understanding of RF pasteurization for agricultural products and promote the industrial-scale applications of RF technology with possible process protocol optimization purposes.

Appraisal of immediate and late effects of mobile phone radiations at 2100 MHz on mitotic activity and DNA integrity in root meristems of Allium cepa

The present study evaluated the potential of 2100 MHz radiofrequency radiations to act as cytotoxic and genotoxic agent. Fresh onion (Allium cepa L.) roots were exposed to electromagnetic field radiations (EMF-r) for different durations (1 h and 4 h) and evaluated for mitotic index (MI), phase index, chromosomal aberrations, and DNA damage. DNA damage was investigated with the help of the comet assay by assessing various parameters like % head DNA (HDNA), % tail DNA (TDNA), tail moment (TM), and olive tail moment (OTM). Effects of EMF-r exposure were also compared with that of methyl methanesulfonate (MMS; 90 μM), which acted as a positive control. The post-exposure effects of EMF-r after providing the test plants with an acclimatization period of 24 h were also evaluated. Compared to the control, a significant increase in the MI and aberration percentage was recorded upon 4 h of exposure. However, no specific trend of phase index in response to exposure was detected. EMF-r exposure incited DNA damage with a significant decrease in HDNA accompanied by an increase in TDNA upon exposure of 4 h. However, TM and OTM did not change significantly upon exposure as compared to that of control. Analysis of the post-exposure effects of EMF-r did not show any significant change/recovery. Our data, thus, suggest the potential cytotoxic and genotoxic nature of 2100 MHz EMF-r. Our study bears great significance in view of the swiftly emergent EMF-r in the surrounding environment and their potential for inciting aberrations at the chromosomal level, thus posing a genetic hazard.

Role of Mitochondria in the Oxidative Stress Induced by Electromagnetic Fields: Focus on Reproductive Systems

Modern technologies relying on wireless communication systems have brought increasing levels of electromagnetic field (EMF) exposure. This increased research interest in the effects of these radiations on human health. There is compelling evidence that EMFs affect cell physiology by altering redox-related processes. Considering the importance of redox milieu in the biological competence of oocyte and sperm, we reviewed the existing literature regarding the effects of EMFs on reproductive systems. Given the role of mitochondria as the main source of reactive oxygen species (ROS), we focused on the hypothesis of a mitochondrial basis of EMF-induced reproductive toxicity. MEDLINE, Web of Science, and Scopus database were examined for peer-reviewed original articles by searching for the following keywords: “extremely low frequency electromagnetic fields (ELF-EMFs),” “radiofrequency (RF),” “microwaves,” “Wi-Fi,” “mobile phone,” “oxidative stress,” “mitochondria,” “fertility,” “sperm,” “testis,” “oocyte,” “ovarian follicle,” and “embryo.” These keywords were combined with other search phrases relevant to the topic. Although we reported contradictory data due to lack of uniformity in the experimental designs, a growing body of evidence suggests that EMF exposure during spermatogenesis induces increased ROS production associated with decreased ROS scavenging activity. Numerous studies revealed the detrimental effects of EMFs from mobile phones, laptops, and other electric devices on sperm quality and provide evidence for extensive electron leakage from the mitochondrial electron transport chain as the main cause of EMF damage. In female reproductive systems, the contribution of oxidative stress to EMF-induced damages and the evidence of mitochondrial origin of ROS overproduction are reported, as well. In conclusion, mitochondria seem to play an important role as source of ROS in both male and female reproductive systems under EMF exposure. Future and more standardized studies are required for a better understanding of molecular mechanisms underlying EMF potential challenge to our reproductive system in order to improve preventive strategies.

Multivariable quantitative relation between cell viability and the exposure parameters of 9.33 GHz RF-EMP irradiation

Qualitative analysis of the influence of a certain exposure parameter is commonly performed in bioelectromagnetic studies. However, since the exposure condition requires the control of multiple parameters, the diverse results caused by different combinations of these parameters requires further quantitative study of the multivariable (exposure parameters)-bioeffect relation to identify the rule describing bioelectromagnetic effects. The present work investigated the relation between cell viability and the three main exposure parameters (electric intensity (E_s), pulse duration (τ) and pulse number (N)) of 9.33 GHz radiofrequency electromagnetic field (RF-EMP). Experiments showed that the inhibitory rate of cell viability (ρ) had a proportional relationship with E_s and exponential relationship with N; the equation [Formula: see text] is proposed to quantitatively describe the relation between the cell viability and these three exposure parameters. This equation can be used to predict the significance of a 9.33 GHz RF-EMP-induced bioeffect under the conditions E_s <10⁶ kV/m, N < 100, and 300 < τ < 750 ns, under which nonthermal bioeffects dominate for 9.33GHz RF-EMP exposure.