Single vs. repeated microwave exposure: effects on benzodiazepine receptors in the brain of the rat

Cellular and molecular effects of non-ionizing electromagnetic fields

The way that living cells respond to non-ionizing electromagnetic fields (EMF), including static/extremely-low frequency and radiofrequency electromagnetic fields, fits the pattern of 'cellular stress response' - a mechanism manifest at the cellular level intended to preserve the entire organism. It is a set pattern of cellular and molecular responses to environmental stressors, such as heat, ionizing radiation, oxidation, etc. It is triggered by cellular macromolecular damage (in proteins, lipids, and DNA) with the goal of repairing and returning cell functions to homeostasis. The pattern is independent of the type of stressor encountered. It involves cell cycle arrest, induction of specific molecular mechanisms for repair, damage removal, cell proliferation, and cell death if damage is too great. This response could be triggered by EMF-induced alternation in oxidative processes in cells. The concept that biological response to EMF is a 'cellular stress response' explains many observed effects of EMF, such as nonlinear dose- and time-dependency, increased and decreased risks of cancer and neurodegenerative diseases, enhanced nerve regeneration, and bone healing. These responses could be either detrimental or beneficial to health, depending on the duration and intensity of the exposure, as well as specific aspects of the living organism being exposed. A corollary to electromagnetic hypersensitivity syndrome (EHS) could be an inappropriate response of the hippocampus/limbic system to EMF, involving glucocorticoids on the hypothalamic-pituitary-adrenal axis.

Effects of Head-Only Exposure to 900 MHz GSM Electromagnetic Fields in Rats: Changes in Neuronal Activity as Revealed by c-Fos Imaging without Concomitant Cognitive Impairments

Over the last two decades, animal models have been used to evaluate the physiological and cognitive effects of mobile phone exposure. Here, we used a head-only exposure system in rats to determine whether exposure to 900 MHz GSM electromagnetic fields (EMFs) induces regional changes in neuronal activation as revealed by c-Fos imaging. In a first study, rats were exposed for 2 h to brain average specific absorption rates (BASARs) ranging from 0.5 to 6 W/kg. Changes in neuronal activation were found to be dose-dependent, with significant increases in c-Fos expression occurring at BASAR of 1 W/kg in prelimbic, infralimbic, frontal, and cingulate cortices. In a second study, rats were submitted to either a spatial working memory (WM) task in a radial maze or a spatial reference memory (RM) task in an open field arena. Exposures (45 min) were conducted before each daily training session (BASARs of 1 and 3.5 W/kg). Control groups included sham-exposed and control cage animals. In both tasks, behavioral performance evolved similarly in the four groups over testing days. However, c-Fos staining was significantly reduced in cortical areas (prelimbic, infralimbic, frontal, cingulate, and visual cortices) and in the hippocampus of animals engaged in the WM task (BASARs of 1 and 3.5 W/kg). In the RM task, EMF exposure-induced decreases were limited to temporal and visual cortices (BASAR of 1 W/kg). These results demonstrate that both acute and subchronic exposures to 900 MHz EMFs can produce region-specific changes in brain activity patterns, which are, however, insufficient to induce detectable cognitive deficits in the behavioral paradigms used here.

Establishment of injury models in studies of biological effects induced by microwave radiation

Microwave radiation has been widely used in various fields, such as communication, industry, medical treatment, and military applications. Microwave radiation may cause injuries to both the structures and functions of various organs, such as the brain, heart, reproductive organs, and endocrine organs, which endanger human health. Therefore, it is both theoretically and clinically important to conduct studies on the biological effects induced by microwave radiation. The successful establishment of injury models is of great importance to the reliability and reproducibility of these studies. In this article, we review the microwave exposure conditions, subjects used to establish injury models, the methods used for the assessment of the injuries, and the indicators implemented to evaluate the success of injury model establishment in studies on biological effects induced by microwave radiation.

Possible Effects of Radiofrequency Electromagnetic Field Exposure on Central Nerve System

Technological advances of mankind, through the development of electrical and communication technologies, have resulted in the exposure to artificial electromagnetic fields (EMF). Technological growth is expected to continue; as such, the amount of EMF exposure will continue to increase steadily. In particular, the use-time of smart phones, that have become a necessity for modern people, is steadily increasing. Social concerns and interest in the impact on the cranial nervous system are increased when considering the area where the mobile phone is used. However, before discussing possible effects of radiofrequency-electromagnetic field (RF-EMF) on the human body, several factors must be investigated about the influence of EMFs at the level of research using in vitro or animal models. Scientific studies on the mechanism of biological effects are also required. It has been found that RF-EMF can induce changes in central nervous system nerve cells, including neuronal cell apoptosis, changes in the function of the nerve myelin and ion channels; furthermore, RF-EMF act as a stress source in living creatures. The possible biological effects of RF-EMF exposure have not yet been proven, and there are insufficient data on biological hazards to provide a clear answer to possible health risks. Therefore, it is necessary to study the biological response to RF-EMF in consideration of the comprehensive exposure with regard to the use of various devices by individuals. In this review, we summarize the possible biological effects of RF-EMF exposure.

Chronic Nonmodulated Microwave Radiations in Mice Produce Anxiety-like and Depression-like Behaviours and Calcium- and NO-related Biochemical Changes in the Brain

The present study was aimed to investigate behavioural and biochemical effects of chronic exposure of amplitude modulated and non-modulated microwave radiation on laboratory mice. Chronic microwave exposures were executed with 2.45 GHz of either modulated (power density, 0.029 mW/cm²; specific absorption rate, 0.019 W/Kg with sinusoidal modulation of 400 Hz) or nonmodulated continuous sinusoidal wave (power density, 0.033 mW/cm²; specific absorption rate, 0.023 W/Kg) for 2 hrs daily for 1 month. Mice subjected to non-modulated microwave exposure had significantly increased acetylcholinesterase activity and increased intracellular calcium and nitric oxide levels in the cerebral cortex and hippocampus, and also had increased glucose and corticosterone levels in blood compared to control mice. These non-modulated microwave-exposed mice exhibited anxiety-like and depression-like behaviours. In contrast, mice exposed to modulated microwave for the same period did not show such changes in concomitant biochemical and behavioural analyses. These results suggest that chronic non-modulated microwave, but not modulated microwave, radiation may cause anxiety-like and depression-like behaviours and calcium- and NO-related biochemical changes in the brain.

Behavioral in-effectiveness of high frequency electromagnetic field in mice

The present investigation was carried out with an objective to study the influence of high frequency electromagnetic field (HF-EMF) on anxiety, obsessive compulsive disorder (OCD) and depression-like behavior. For exposure to HF-EMF, non-magnetic material was used to fabricate the housing. Mice were exposed to HF-EMF (2.45GHz), 60min/day for 7 or 30 or 60 or 90 or 120days. The exposure was carried out by switching-on inbuilt class-I BLUETOOTH device that operates on 2.45GHz frequency in file transfer mode at a peak density of 100mW. Mice were subjected to the assessment of anxiety, OCD and depression-like behavior for 7 or 30 or 60 or 90 or 120days of exposure. The anxiety-like behavior was assessed by elevated plus maze, open field test and social interaction test. OCD-like behavior was assessed by marble burying behavior, whereas depression-like behavior was assessed by forced swim test and tail suspension test. The present experiment demonstrates that up to 120days of exposure to HF-EMF does not produce anxiety, OCD and depression-like behavior in mice.

Emerging synergisms between drugs and physiologically-patterned weak magnetic fields: implications for neuropharmacology and the human population in the twenty-first century

Synergisms between pharmacological agents and endogenous neurotransmitters are familiar and frequent. The present review describes the experimental evidence for interactions between neuropharmacological compounds and the classes of weak magnetic fields that might be encountered in our daily environments. Whereas drugs mediate their effects through specific spatial (molecular) structures, magnetic fields mediate their effects through specific temporal patterns. Very weak (microT range) physiologically-patterned magnetic fields synergistically interact with drugs to strongly potentiate effects that have classically involved opiate, cholinergic, dopaminergic, serotonergic, and nitric oxide pathways. The combinations of the appropriately patterned magnetic fields and specific drugs can evoke changes that are several times larger than those evoked by the drugs alone. These novel synergisms provide a challenge for a future within an electromagnetic, technological world. They may also reveal fundamental, common physical mechanisms by which magnetic fields and chemical reactions affect the organism from the level of fundamental particles to the entire living system.

The action of pulse-modulated GSM radiation increases regional changes in brain activity and c-Fos expression in cortical and subcortical areas in a rat model of picrotoxin-induced seizure proneness

The action of the pulse-modulated GSM radiofrequency of mobile phones has been suggested as a physical phenomenon that might have biological effects on the mammalian central nervous system. In the present study, GSM-exposed picrotoxin-pretreated rats showed differences in clinical and EEG signs, and in c-Fos expression in the brain, with respect to picrotoxin-treated rats exposed to an equivalent dose of unmodulated radiation. Neither radiation treatment caused tissue heating, so thermal effects can be ruled out. The most marked effects of GSM radiation on c-Fos expression in picrotoxin-treated rats were observed in limbic structures, olfactory cortex areas and subcortical areas, the dentate gyrus, and the central lateral nucleus of the thalamic intralaminar nucleus group. Nonpicrotoxin-treated animals exposed to unmodulated radiation showed the highest levels of neuronal c-Fos expression in cortical areas. These results suggest a specific effect of the pulse modulation of GSM radiation on brain activity of a picrotoxin-induced seizure-proneness rat model and indicate that this mobile-phone-type radiation might induce regional changes in previous preexcitability conditions of neuronal activation.

Whole-body exposure to 2.45GHz electromagnetic fields does not alter 12-arm radial-maze with reduced access to spatial cues in rats

Lai et al. [Lai H, Horita A, Guy AW. Microwave irradiation affects radial-arm maze performance in the rat. Bioelectromagnetics 1994;15(2):95-104] reported that exposure of rats to pulsed 2.45 GHz microwaves altered maze performance. Their maze was bordered by 20 cm high opaque walls. Using a maze test based on unrestrained access to spatial cues (no walls), we could not replicate this result [Cassel JC, Cosquer B, Galani R, Kuster N. Whole-body exposure to 2.45 GHz electromagnetic fields does not alter radial-maze performance in rats. Behav Brain Res 2004;155:37-43]. Here, we attempted another replication using a maze apparatus bordered by 30 cm high opaque walls. Performance of exposed rats was normal. These results show that microwave exposure as used herein does not alter spatial working memory, when access to spatial cues is reduced.

Whole-body exposure to 2.45 GHz electromagnetic fields does not alter radial-maze performance in rats

Mobile communication is based on utilization of electromagnetic fields (EMFs) in the frequency range of 0.3-300 GHz. Human and animal studies suggest that EMFs, which are in the 0.1 MHz-300 GHz range, might interfere with cognitive processes. In 1994, a report by Lai et al. [Bioelectromagnetics 15 (1994) 95-104] showed that whole-body exposure of rats to pulsed 2.45 GHz microwaves (2 micros pulse width, 500 pps, and specific absorption rate [SAR] 0.6 W/kg) for 45 min resulted in altered spatial working memory assessed in a 12-arm radial-maze task. Surprisingly, there has been only one attempt to replicate this experiment so far [Bioelectromagnetics 25 (2004) 49-57]; confirmation of the Lai et al. experiment failed. In the present study, rats were tested in a 12-arm radial-maze subsequently to a daily exposure to 2.45 GHz microwaves (2 micros pulse width, 500 pps, and SAR 0.6 W/kg) for 45 min. The performance of exposed rats was comparable to that found in sham-exposed or in naive rats (no contact with the exposure system). Regarding the methodological details provided by Lai et al. on their testing protocol, our results might suggest that the microwave-induced behavioral alterations measured by these authors might have had more to do with factors liable to performance bias than with spatial working memory per se.

Microwave effects on the nervous system

Studies have evaluated the electroencephalography (EEG) of humans and laboratory animals during and after Radiofrequency (RF) exposures. Effects of RF exposure on the blood-brain barrier (BBB) have been generally accepted for exposures that are thermalizing. Low level exposures that report alterations of the BBB remain controversial. Exposure to high levels of RF energy can damage the structure and function of the nervous system. Much research has focused on the neurochemistry of the brain and the reported effects of RF exposure. Research with isolated brain tissue has provided new results that do not seem to rely on thermal mechanisms. Studies of individuals who are reported to be sensitive to electric and magnetic fields are discussed. In this review of the literature, it is difficult to draw conclusions concerning hazards to human health. The many exposure parameters such as frequency, orientation, modulation, power density, and duration of exposure make direct comparison of many experiments difficult. At high exposure power densities, thermal effects are prevalent and can lead to adverse consequences. At lower levels of exposure biological effects may still occur but thermal mechanisms are not ruled out. It is concluded that the diverse methods and experimental designs as well as lack of replication of many seemingly important studies prevents formation of definite conclusions concerning hazardous nervous system health effects from RF exposure. The only firm conclusion that may be drawn is the potential for hazardous thermal consequences of high power RF exposure.

Microwave exposure induces Hsp70 and confers protection against hypoxia in chick embryos

To determine if microwave exposure could elicit a biological effect in the absence of thermal stress, studies were designed in which chick embryos were exposed to athermal microwave radiation (915 MHz) to look for induction of Hsp70, a protein produced during times of cellular stress that aids in the protection of cellular components. Levels of Hsp70 were found to increase within 2 h, with maximum expression ( approximately 30% higher than controls) typically occurring by 3 h from the start of exposure. Other embryos were exposed to microwave radiation prior to being subjected to hypoxic stress, and were found to have significantly higher survival (P < 0.05) following re-oxygenation than non-exposed controls. The results of these studies indicate that not only can athermal microwave exposures activate the stress protein response pathway; they can also enhance survivability following exposure to a subsequent, potentially lethal stress. From a public health standpoint, it is important that more studies be performed to determine if repeated exposures, a condition likely to be found in cell phone use, are still beneficial.

Skin changes in "screen dermatitis" versus classical UV- and ionizing irradiation-related damage--similarities and differences

An increasing number of persons say that they get cutaneous problems as well as symptoms from certain internal organs, such as the central nervous system (CNS) and the heart, when being close to electric equipment. A major group of these patients are the users of video display terminals (VDTs), who claim to have subjective and objective skin- and mucosa-related symptoms, such as pain, itch, heat sensation, erythema, papules, and pustules. The CNS symptoms are, e.g. dizziness, tiredness, and headache. Erythema, itch, heat sensation, edema and pain are also common symptoms of sunburn (UV dermatitis). Alterations have been observed in cell populations of the skin of patients suffering from so-called "screen dermatitis" similar to those observed in the skin damaged due to ultraviolet (UV) light or ionizing radiation. In "screen dermatitis" patients a much higher number of mast cells have been observed. It is known that UVB irradiation induces mast cell degranulation and release of TNF-alpha. The high number of mast cells present in the "screen dermatitis" patients and the possible release of specific substances, such as histamine, may explain their clinical symptoms of itch, pain, edema and erythema. The most remarkable change among cutaneous cells, after exposure with the above-mentioned irradiation sources, is the disappearance of the Langerhans' cells. This change has also been observed in "screen dermatitis" patients, again pointing to a common cellular and molecular basis. The results of this literature study demonstrate that highly similar changes exist in the skin of "screen dermatitis" patients, as regards the clinical manifestations as well as alterations in the cell populations, and in skin damaged by UV light or ionizing radiation.

Electroencephalographic changes following low energy emission therapy

Low energy emission therapy (LEET) is a novel approach to delivering low levels of amplitude-modulated electromagnetic fields to the human brain. The sleep electroencephalogram (EEG) effects of a 15-min LEET treatment were investigated in a double-find cross-over study to assess sleep induction. Fifty-two healthy volunteers were exposed to both active and inactive LEET treatment sessions, with a minimum interval of 1 week between the two sessions. Baseline EEGs were obtained, and 15-min posttreatment EEGs were recorded and analyzed according to the Loomis classification. A significant increase in the duration of stage B1 sleep (0.58 +/- 2.42 min [mean +/- SD], p = 0.046), decreased latency to the first 10 sec epoch of sleep (-1.23 +/- 5.32 min, p = 0.051) and decreased latency to sleep stage B2 (-1.21 +/- 5.25 min, p = 0.052) were observed after active treatment. Additionally, establishment of slow waves with progression from stages B to C was significantly more pronounced after active LEET treatment (p = 0.040). A combined analysis of these results with those of an identical study performed in Denver showed that LEET had a significant effect on afternoon sleep induction and maintenance with shorter sleep latencies (decreased latency to the first 10 sec epoch of sleep; -1.00 +/- 5.51 min, p = 0.033; decreased latency to sleep stage B2; -1.49 +/- 5.40 min, p = 0.003), an increased duration of stage B2 (0.67 +/- 2.50 min, p = 0.003), an increase in the total duration of sleep (0.69 +/- 4.21 min, p = 0.049), and a more prominent establishment of slow waves with progression to a deeper sleep stage (p = 0.006). It is concluded that the intermittent 42.7 HZ amplitude modulation of 27.12-MHz electromagnetic fields results in EEG changes consistent with shorter sleep latencies, longer sleep duration, and deeper sleep in healthy subjects.

Influence of microwave exposure on chlordiazepoxide effects in the mouse staircase test

To ascertain whether behavioral effects of benzodiazepines are altered by exposure to microwave radiation, we compared the performance of male, Swiss CD1 mice in the staircase test 30 min after pretreatment with chlordiazepoxide (8, 16, and 32 mg/kg, IP) and immediately following a 5-min exposure to microwave radiation (4, 12, and 36 W/kg, continuous wave, 1.8 or 4.7 GHz). In this paradigm, chlordiazepoxide reduction in the number of rears (NR) and number of steps ascended (NSA) is postulated to reflect anxiolytic and sedative drug effects, respectively. In sham-exposed mice, increasing doses of chlordiazepoxide increased NSA without affecting NR, increased NSA and decreased NR, then decreased both NSA and NR. Microwave exposure generally did not alter NSA or NR in mice pretreated with lower doses of chlordiazepoxide. However, in mice pretreated with 32 mg/kg chlordiazepoxide, exposure to 36 W/kg microwave radiation significantly reversed the reductions in NSA and NR at 4.7 GHz but not at 1.8 GHz. These findings indicate that exposure to microwave radiation can selectively alter effects of chlordiazepoxide in this psychopharmacological paradigm.

Research on the neurological effects of nonionizing radiation at the University of Washington

This paper reviews research on neurological effects of low-level microwave irradiation, which was performed at the University of Washington, during the decade of the 1980s. We studied in the rat the effects of microwave exposure on the actions of various psychoactive drugs, on the activity of cholinergic systems in the brain, and on the neural mechanisms involved. Our results indicate that endogenous opioids play an important mediating role in some of the neurological effects of microwaves, and that parameters of microwave exposure are important determinants of the outcome of the microwave effects.