Effects of early-onset radiofrequency electromagnetic field exposure (GSM 900 MHz) on behavior and memory in rats

Radiofrequency radiation and Alzheimer's disease: harmful and therapeutic implications

PURPOSE

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by memory loss and cognitive decline. The relationship between AD and radiofrequency (RF) radiation emitted by wireless devices remains under investigation. The aim of this review is to comprehensively explore the effects of RF radiation on AD by evaluating existing literature. This review used Web of Science, Scopus, and PubMed to find relevant studies on AD and RF radiation. This review evaluates a total of 81 studies, including animal models, human studies, and in vitro experiments, with results summarized in tables for clarity.

CONCLUSION

Some studies suggest RF aggravates AD by increasing oxidative stress, impairing blood-brain barrier integrity, and promoting amyloid-beta deposition. Conversely, other studies indicate RF may have protective benefits, such as enhancing brain mitochondrial functions and reducing amyloid-beta levels. Understanding the RF-AD relationship, including parameters like frequency and exposure time, is crucial for therapeutic strategies. The studies reviewed highlight RF radiation's dual effects on AD, underscoring the need for a detailed approach. Further studies are required to clarify these effects and inform preventive and therapeutic measures.

Electromagnetic field protects against cognitive and synaptic plasticity impairment induced by electrical kindling in rats

Kindling results in abnormal synaptic potentiation and significant impairment in learning and memory. Electromagnetic field (EMF) effects on learning and memory in kindled animals and its effects on hippocampal neural activity are largely unknown. In the current study, the effects of EMF on learning and memory, as well as hippocampal synaptic plasticity, in kindled rats were investigated. EMF (10 mT; 100 Hz) was applied to fully kindled animals one hour/day for a period of one week. The behavioral and electrophysiological studies were performed 24 h following the EMF application. The kindled rats showed spatial learning deficits during the training phase of the Morris water maze (MWM) test. Moreover, there were increments in escape latency and path length compared to the sham group. The kindled rats spent less time in the target-quadrant probe test, indicating spatial memory impairment. Applying EMF to the KEMF group (kindling + EMF) restored learning and memory, and decreased escape latency and path length significantly compared to the kindled group. EMF alone had no significant effects on the learning and memory parameters. Based on the open field (OF) test results, EMF alone in the EMF group, but not in the kindled or the KEMF groups, decreased the total traveled distance and increased the spent time in the peripheral zone, compared to the sham group. Based on electrophysiological results, applying EMF in the KEMF group returned the ability of synaptic potentiation to the hippocampal CA1 area and high-frequency stimulation induced long-term potentiation (LTP). Accordingly, EMF can be considered a potential therapy for seizure-induced deficits in learning and memory.

Prenatal and early postnatal exposure to radiofrequency waves (900 MHz) adversely affects passive avoidance learning and memory

Prenatal and early postnatal are the most sensitive and high-risk periods to expose to electromagnetic fields (EMFs). This study aimed to investigate the effect of prenatal and early postnatal exposure to 900 MHz radiofrequency waves (RFWs) emitted from a base transceiver station antenna on passive avoidance learning and memory (PALM) and hippocampus histomorphology. Female Sprague Dawley rats (190-230 g) were paired with males. The mated rats, confirmed by observing a vaginal plug, were divided into two groups; control and exposed. The control group (n = 7) was not exposed to RFW. The exposed group was divided into three subgroups (n = 8); exposed Ⅰ, exposed during the gestational period (fetal life), and exposed Ⅱ and Ⅲ (postnatal exposure), exposed to RFW during the first 21 days of life, for 2 h/d and 4 h/d, respectively. PALM was evaluated by a shuttle box in 45-day-old pups. Learning and memory of animals were demonstrated as the duration of remaining within the light area, which is called the lighting time. Histological sections were prepared from brain tissues and stained with hematoxylin and eosin. An impairment in the PALM performance was noticed in all exposed subgroups (Ⅰ, Ⅱ, and Ⅲ) (p < 0.05). Learning (short-term memory) and retention (long-term memory) behaviors were more affected in exposed subgroup Ⅰ (prenatal exposed) compared to other postnatal exposed subgroups (Ⅱ and Ⅲ). Also, a mild decrease in the density of pyramidal cells was observed in the hippocampus of exposed subgroups (Ⅰ and Ⅲ). Prenatal and early postnatal exposure to 900 MHz RFW adversely affected PALM performance and hippocampus tissue in rat pups with more impact for prenatal period exposure.

Exposure to Electromagnetic Field during Gestation Adversely Affects the Electrophysiological Properties of Purkinje Cells in Rat Offspring

Background:

Prenatal adverse effects of radiofrequency electromagnetic fields (RF-EMF) exposure on nervous system are an issue of major concern.

Objective:

Thus, in this study we evaluated the membrane current flow properties of Purkinje neurons after maternal exposure to 900 MHz pulsed RF-EMF.

Material and Methods:

In this experimental study, during all days of pregnancy, rats in the EMF-exposed group were exposed to 900 MHz pulsed-EMF radiation for 6 h per day. The effects of RF-EMF exposure on the electrophysiological properties of the Purkinje cerebellum neurons from male pups were evaluated by whole-cell patch clamp recordings in current and voltage clamp modes. In voltage-clamp experiments, the holding potential was -60mV, and a depolarizing voltage step (1000 ms duration) was applied from -60 to +50 mV in 10 mV increments at 2s intervals.

Results:

The exposure group demonstrated reduced spontaneous firing associated with upward and rightward shift in I/V curve compared to the control rats. Moreover, the peak amplitude of the current for the exposure pups also revealed a significant decrement. The reversal potential was +40 mV and +20 mV for the control and RF-EMF groups, respectively and showed significant differences between the two groups.

Conclusion:

The decrease in ion’s conductance could be attributed to the observed decrease in the voltage onset of the inward current, peak amplitude and voltage shift.

Can Low-Level Exposure to Radiofrequency Fields Effect Cognitive Behaviour in Laboratory Animals? A Systematic Review of the Literature Related to Spatial Learning and Place Memory

This review considers whether exposure to low-level radiofrequency (RF) fields, mostly associated with mobile phone technology, can influence cognitive behaviour of laboratory animals. Studies were nominated for inclusion using an a priori defined protocol with preselected criteria, and studies were excluded from analysis if they did not include sufficient details about the exposure, dosimetry or experimental protocol, or if they lacked a sham-exposed group. Overall, 62 studies were identified that have investigated the effects of RF fields on spatial memory and place learning and have been published since 1993. Of these, 17 studies were excluded, 20 studies reported no significant field-related effects, 21 studies reported significant impairments or deficits, and four studies reported beneficial consequences. The data do not suggest whether these outcomes are related to specific differences in exposure or testing conditions, or simply represent chance. However, some studies have suggested possible molecular mechanisms for the observed effects, but none of these has been substantiated through independent replication. Further behavioural studies could prove useful to resolve this situation, and it is suggested that these studies should use a consistent animal model with standardized exposure and testing protocols, and with detailed dosimetry provided by heterogeneous, anatomically-realistic animal models.

The effects of a continuous 1-h a day 900-MHz electromagnetic field applied throughout early and mid-adolescence on hippocampus morphology and learning behavior in late adolescent male rats

The purpose of this study was to investigate hippocampus morphology and changes in learning behavior in male rats in late adolescence exposed to the effect of a continuous 1-h a day 900-megahertz (MHz) electromagnetic field (EMF). Twenty-four male Sprague Dawley rats aged 3-weeks were divided equally into control, sham and EMF groups. EMF group rats were exposed to a 900-MHz EMF inside an EMF cage, while the sham group rats were placed in the same cage but were not exposed to such an effect. No procedure was performed on the control group. Following 25-day application of EMF, passive avoidance, 8-arm radial maze and Y-maze tests were applied to determine rats' learning and memory performances. Open field and rotarod tests were applied to assess locomotor activity. At the end of the tests, the animals' brains were removed. Sections were taken and stained with toluidine blue. The regions of the hippocampus were subjected to histopathological evaluation. At histopathological examination, impairments of pyramidal and granular cell structures were observed in the EMF group hippocampus. No significant change was observed in learning, memory or locomotor behavior in any group. In conclusion, 900-MHz EMF applied in early and mid-adolescence causes no changes in learning, memory or locomotor behavior.

Impact of Long-Term RF-EMF on Oxidative Stress and Neuroinflammation in Aging Brains of C57BL/6 Mice

The expansion of mobile phone use has raised questions regarding the possible biological effects of radiofrequency electromagnetic field (RF-EMF) exposure on oxidative stress and brain inflammation. Despite accumulative exposure of humans to radiofrequency electromagnetic fields (RF-EMFs) from mobile phones, their long-term effects on oxidative stress and neuroinflammation in the aging brain have not been studied. In the present study, middle-aged C57BL/6 mice (aged 14 months) were exposed to 1950 MHz electromagnetic fields for 8 months (specific absorption rate (SAR) 5 W/kg, 2 h/day, 5 d/week). Compared with those in the young group, levels of protein (3-nitro-tyrosine) and lipid (4-hydroxy-2-nonenal) oxidative damage markers were significantly increased in the brains of aged mice. In addition, levels of markers for DNA damage (8-hydroxy-2'-deoxyguanosine, p53, p21, γH2AX, and Bax), apoptosis (cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase 1 (PARP-1)), astrocyte (GFAP), and microglia (Iba-1) were significantly elevated in the brains of aged mice. However, long-term RF-EMF exposure did not change the levels of oxidative stress, DNA damage, apoptosis, astrocyte, or microglia markers in the aged mouse brains. Moreover, long-term RF-EMF exposure did not alter locomotor activity in aged mice. Therefore, these findings indicate that long-term exposure to RF-EMF did not influence age-induced oxidative stress or neuroinflammation in C57BL/6 mice.

Exposure to GSM 900-MHz mobile radiation impaired inhibitory avoidance memory consolidation in rat: Involvements of opioidergic and nitrergic systems

The use of mobile phones is increasing, and the main health concern is the possible deleterious effects of radiation on brain functioning. The present study aimed to examine the effects of exposure to a global system for mobile communication (GSM) with mobile phones on inhibitory avoidance (IA) memory performance as well as the involvement of endogenous opioids and nitric oxide (NO) in this task. Male Wistar rats, 10-12 weeks old, were used. The results showed that four weeks of mobile phone exposure impaired IA memory performance in rats. The results also revealed that post-training, but not pre-training, as well as pre-test intracerebroventricular (i.c.v.) injections of naloxone (0.4, 4 and 40 ng/rat), dose-dependently recovered the impairment of IA memory performance induced by GSM radiation. Additionally, the impairment of IA memory performance was completely recovered in the exposed animals with post-training treatment of naloxone (40 ng/rat) plus pre-test i.c.v. injections of L-arginine (100 and 200 nmol/rat). However, pre-test i.c.v. injections of L-NAME (10 and 20 nmol/rat), impaired IA memory performance in the animals receiving post-training naloxone (40 ng/rat). In the animals receiving post-training naloxone treatment, the impairment of IA memory performance due to pre-test i.c.v. injections of L-NAME was recovered by the pre-test co-administration of L-arginine. It was concluded that the recovery from impairment of IA memory in GSM-exposed animals with post-training naloxone treatment was the result of blockade of the opioidergic system in early memory consolidation as well as activation of the nitrergic system in the retrieval phase of memory.

A Prospective Cohort Study of Adolescents' Memory Performance and Individual Brain Dose of Microwave Radiation from Wireless Communication

BACKGROUND

The potential impact of microwave radiofrequency electromagnetic fields (RF-EMF) emitted by wireless communication devices on neurocognitive functions of adolescents is controversial. In a previous analysis, we found changes in figural memory scores associated with a higher cumulative RF-EMF brain dose in adolescents.

OBJECTIVE

We aimed to follow-up our previous results using a new study population, dose estimation, and approach to controlling for confounding from media usage itself.

METHODS

RF-EMF brain dose for each participant was modeled. Multivariable linear regression models were fitted on verbal and figural memory score changes over 1 y and on estimated cumulative brain dose and RF-EMF related and unrelated media usage (n=669-676). Because of the hemispheric lateralization of memory, we conducted a laterality analysis for phone call ear preference. To control for the confounding of media use behaviors, a stratified analysis for different media usage groups was also conducted.

RESULTS

We found decreased figural memory scores in association with an interquartile range (IQR) increase in estimated cumulative RF-EMF brain dose scores: -0.22 (95% CI: -0.47, 0.03; IQR: 953 mJ/kg per day) in the whole sample, -0.39 (95% CI: -0.67, -0.10; IQR: 953 mJ/kg per day) in right-side users (n=532), and -0.26 (95% CI: -0.42, -0.10; IQR: 341 mJ/kg per day) when recorded network operator data were used for RF-EMF dose estimation (n=274). Media usage unrelated to RF-EMF did not show significant associations or consistent patterns, with the exception of consistent (nonsignificant) positive associations between data traffic duration and verbal memory.

CONCLUSIONS

Our findings for a cohort of Swiss adolescents require confirmation in other populations but suggest a potential adverse effect of RF-EMF brain dose on cognitive functions that involve brain regions mostly exposed during mobile phone use. https://doi.org/10.1289/EHP2427.

Towards 5G communication systems: Are there health implications?

The spread of radiofrequency electromagnetic fields (RF-EMF) is rising and health effects are still under investigation. RF-EMF promote oxidative stress, a condition involved in cancer onset, in several acute and chronic diseases and in vascular homeostasis. Although some evidences are still controversial, the WHO IARC classified RF-EMF as "possible carcinogenic to humans", and more recent studies suggested reproductive, metabolic and neurologic effects of RF-EMF, which are also able to alter bacterial antibiotic resistance. In this evolving scenario, although the biological effects of 5G communication systems are very scarcely investigated, an international action plan for the development of 5G networks has started, with a forthcoming increment in devices and density of small cells, and with the future use of millimeter waves (MMW). Preliminary observations showed that MMW increase skin temperature, alter gene expression, promote cellular proliferation and synthesis of proteins linked with oxidative stress, inflammatory and metabolic processes, could generate ocular damages, affect neuro-muscular dynamics. Further studies are needed to better and independently explore the health effects of RF-EMF in general and of MMW in particular. However, available findings seem sufficient to demonstrate the existence of biomedical effects, to invoke the precautionary principle, to define exposed subjects as potentially vulnerable and to revise existing limits. An adequate knowledge of pathophysiological mechanisms linking RF-EMF exposure to health risk should also be useful in the current clinical practice, in particular in consideration of evidences pointing to extrinsic factors as heavy contributors to cancer risk and to the progressive epidemiological growth of noncommunicable diseases.

Effect of cell phone radiofrequency radiation on body temperature in rodents: Pilot studies of the National Toxicology Program's reverberation chamber exposure system

Radiofrequency radiation (RFR) causes heating, which can lead to detrimental biological effects. To characterize the effects of RFR exposure on body temperature in relation to animal size and pregnancy, a series of short-term toxicity studies was conducted in a unique RFR exposure system. Young and old B6C3F1 mice and young, old, and pregnant Harlan Sprague-Dawley rats were exposed to Global System for Mobile Communication (GSM) or Code Division Multiple Access (CDMA) RFR (rats = 900 MHz, mice = 1,900 MHz) at specific absorption rates (SARs) up to 12 W/kg for approximately 9 h a day for 5 days. In general, fewer and less severe increases in body temperature were observed in young than in older rats. SAR-dependent increases in subcutaneous body temperatures were observed at exposures ≥6 W/kg in both modulations. Exposures of  ≥10 W/kg GSM or CDMA RFR induced excessive increases in body temperature, leading to mortality. There was also a significant increase in the number of resorptions in pregnant rats at 12 W/kg GSM RFR. In mice, only sporadic increases in body temperature were observed regardless of sex or age when exposed to GSM or CDMA RFR up to 12 W/kg. These results identified SARs at which measurable RFR-mediated thermal effects occur, and were used in the selection of exposures for subsequent toxicology and carcinogenicity studies. Bioelectromagnetics. 39:190-199, 2018. © 2018 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.

Effects of 1800 MHz RF-EMF exposure on DNA damage and cellular functions in primary cultured neurogenic cells

PURPOSE

To systematically evaluate the effects of 1800 MHz radiofrequency electromagnetic fields (RF-EMF) exposure on DNA damage and cellular functions in primary cultured neurogenic cells.

MATERIALS AND METHODS

The primary cultured astrocytes, microglia and cortical neurons were exposed to RF-EMF at a SAR of 4.0 W/kg. The DNA damage was evaluated by γH2AX foci formation assay. The secretions of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) in astrocytes and microglia, microglial phagocytic activity and neuronal development were examined by enzyme-linked immunosorbent assay, phagocytosis assay and immunofluorescent staining on microtubule-associated protein tau, microtubule-associated protein 2, postsynaptic density 95 and gephyrin, respectively.

RESULTS

RF-EMF exposure did not significantly induce γH2AX foci formation in three primary cultured neurogenic cells. Furthermore, RF-EMF exposure did not significantly affect the secretion of cytokines in astrocytes and microglia, and the morphological indicators of dendrites or synapses of cortical neurons. However, the exposure significantly reduced the phagocytic activity of microglia and inhibited the axon branch length and branch number of cortical neurons.

CONCLUSIONS

Our data demonstrated that exposure to RF-EMF did not elicit DNA damage but inhibited the phagocytic ability of microglia and the axon branch length and branch number of cortical neurons.

Effects of 1.8 GHz Radiofrequency Fields on the Emotional Behavior and Spatial Memory of Adolescent Mice

The increasing use of mobile phones by teenagers has raised concern about the cognitive effects of radiofrequency (RF) fields. In this study, we investigated the effects of 4-week exposure to a 1.8 GHz RF field on the emotional behavior and spatial memory of adolescent male mice. Anxiety-like behavior was evaluated by open field test (OFT) and elevated plus maze (EPM) test, while depression-like behavior was evaluated by sucrose preference test (SPT), tail suspension test (TST) and forced swim test (FST). The spatial learning and memory ability were evaluated by Morris water maze (MWM) experiments. The levels of amino acid neurotransmitters were determined by liquid chromatography-mass spectrometry (LC-MS). The histology of the brain was examined by hematoxylin-eosin (HE) staining. It was found that the depression-like behavior, spatial memory ability and histology of the brain did not change obviously after RF exposure. However, the anxiety-like behavior increased in mice, while, the levels of γ-aminobutyric acid (GABA) and aspartic acid (Asp) in cortex and hippocampus significantly decreased after RF exposure. These data suggested that RF exposure under these conditions do not affect the depression-like behavior, spatial memory and brain histology in adolescent male mice, but it may however increase the level of anxiety, and GABA and Asp were probably involved in this effect.

Acute Neuroinflammation Promotes Cell Responses to 1800 MHz GSM Electromagnetic Fields in the Rat Cerebral Cortex

Mobile phone communications are conveyed by radiofrequency (RF) electromagnetic fields, including pulse-modulated global system for mobile communications (GSM)-1800 MHz, whose effects on the CNS affected by pathological states remain to be specified. Here, we investigated whether a 2-h head-only exposure to GSM-1800 MHz could impact on a neuroinflammatory reaction triggered by lipopolysaccharide (LPS) in 2-week-old or adult rats. We focused on the cerebral cortex in which the specific absorption rate (SAR) of RF averaged 2.9 W/kg. In developing rats, 24 h after GSM exposure, the levels of cortical interleukin-1ß (IL1ß) or NOX2 NADPH oxidase transcripts were reduced by 50 to 60%, in comparison with sham-exposed animals (SAR = 0), as assessed by RT-qPCR. Adult rats exposed to GSM also showed a 50% reduction in the level of IL1ß mRNA, but they differed from developing rats by the lack of NOX2 gene suppression and by displaying a significant growth response of microglial cell processes imaged in anti-Iba1-stained cortical sections. As neuroinflammation is often associated with changes in excitatory neurotransmission, we evaluated changes in expression and phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the adult cerebral cortex by Western blot analyses. We found that GSM exposure decreased phosphorylation at two residues on the GluA1 AMPAR subunit (serine 831 and 845). The GSM-induced changes in gene expressions, microglia, and GluA1 phosphorylation did not persist 72 h after RF exposure and were not observed in the absence of LPS pretreatment. Together, our data provide evidence that GSM-1800 MHz can modulate CNS cell responses triggered by an acute neuroinflammatory state.

Maternal cell phone use in early pregnancy and child's language, communication and motor skills at 3 and 5 years: the Norwegian mother and child cohort study (MoBa)

Background

Cell phone use during pregnancy is a public health concern. We investigated the association between maternal cell phone use in pregnancy and child’s language, communication and motor skills at 3 and 5 years.

Methods

This prospective study includes 45,389 mother-child pairs, participants of the MoBa, recruited at mid-pregnancy from 1999 to 2008. Maternal frequency of cell phone use in early pregnancy and child language, communication and motor skills at 3 and 5 years, were assessed by questionnaires. Logistic regression was used to estimate the associations.

Results

No cell phone use in early pregnancy was reported by 9.8% of women, while 39%, 46.9% and 4.3% of the women were categorized as low, medium and high cell phone users. Children of cell phone user mothers had 17% (OR = 0.83, 95% CI: 0.77, 0.89) lower adjusted risk of having low sentence complexity at 3 years, compared to children of non-users. The risk was 13%, 22% and 29% lower by low, medium and high maternal cell phone use. Additionally, children of cell phone users had lower risk of low motor skills score at 3 years, compared to children of non-users, but this association was not found at 5 years. We found no association between maternal cell phone use and low communication skills.

Conclusions

We reported a decreased risk of low language and motor skills at three years in relation to prenatal cell phone use, which might be explained by enhanced maternal-child interaction among cell phone users. No evidence of adverse neurodevelopmental effects of prenatal cell phone use was reported.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4672-2) contains supplementary material, which is available to authorized users.

Review of the Evidence that Transcranial Electromagnetic Treatment will be a Safe and Effective Therapeutic Against Alzheimer's Disease

We have demonstrated in multiple studies that daily, long-term electromagnetic field (EMF) treatment in the ultra-high frequency range not only protects Alzheimer's disease (AD) transgenic mice from cognitive impairment, but also reverses such impairment in aged AD mice. Moreover, these beneficial cognitive effects appear to be through direct actions on the AD process. Based on a large array of pre-clinical data, we have initiated a pilot clinical trial to determine the safety and efficacy of EMF treatment to mild-moderate AD subjects. Since it is important to establish the safety of this new neuromodulatory approach, the main purpose of this review is to provide a comprehensive assessment of evidence supporting the safety of EMFs, particularly through transcranial electromagnetic treatment (TEMT). In addition to our own pre-clinical studies, a rich variety of both animal and cell culture studies performed by others have underscored the anticipated safety of TEMT in clinical AD trials. Moreover, numerous clinical studies have determined that short- or long-term human exposure to EMFs similar to those to be provided clinically by TEMT do not have deleterious effects on general health, cognitive function, or a variety of physiologic measures-to the contrary, beneficial effects on brain function/activity have been reported. Importantly, such EMF exposure has not been shown to increase the risk of any type of cancer in human epidemiologic studies, as well as animal and cell culture studies. In view of all the above, clinical trials of safety/efficacy with TEMT to AD subjects are clearly warranted and now in progress.