Effect of low frequency modulated microwave exposure on human EEG: individual sensitivity

The aim of this study was to evaluate the effect of modulated microwave exposure on human EEG of individual subjects. The experiments were carried out on four different groups of healthy volunteers. The 450 MHz microwave radiation modulated at 7 Hz (first group, 19 subjects), 14 and 21 Hz (second group, 13 subjects), 40 and 70 Hz (third group, 15 subjects), 217 and 1000 Hz (fourth group, 19 subjects) frequencies was applied. The field power density at the scalp was 0.16 mW/cm(2). The calculated spatial peak SAR averaged over 1 g was 0.303 W/kg. Ten cycles of the exposure (1 min off and 1 min on) at fixed modulation frequencies were applied. All subjects completed the experimental protocols with exposure and sham. The exposed and sham-exposed subjects were randomly assigned. A computer also randomly assigned the succession of modulation frequencies. Our results showed that microwave exposure increased the EEG energy. Relative changes in the EEG beta1 power in P3-P4 channels were selected for evaluation of individual sensitivity. The rate of subjects significantly affected is similar in all groups except for the 1000 Hz group: in first group 3 subjects (16%) at 7 Hz modulation; in second group 4 subjects (31%) at 14 Hz modulation and 3 subjects (23%) at 21 Hz modulation; in third group 3 subjects (20%) at 40 Hz and 2 subjects (13%) at 70 Hz modulation; in fourth group 3 subjects (16%) at 217 Hz and 0 subjects at 1000 Hz modulation frequency.     

Space efficient system for small animal, whole body microwave exposure at 1.6 GHz

A space efficient, whole body microwave exposure system for unrestrained laboratory animals utilizing a flared parallel plate waveguide is described. The system comprises an Iridium wireless signal source, signal generator, power supply and amplifier (400 W), a coax to waveguide transition, an open ended, flared parallel plate waveguide, and animal exposure area with a dipole field sensing antenna. Across the waveguide aperture the system provides uniform exposure (+/-3 dB incident RF power density) for small animals (rats, mice or hamsters) in up to 18 standard cages for housing groups of animals. Overall system dimensions are 3.6 m (d)x2.4 m (w)x1.6 m (h). Operating at 1.62 GHz, the system provided average power density of 3.7 W/m(2) in the cage area, resulting in a calculated whole body dose of 0.07 W/kg and a calculated average brain dose of 0.19 W/kg.     

Effect of 2450 MHz microwave exposure on behavioural thermoregulation in mice

1. 1.|The purpose of this study was to determine the threshold specific absorption rate (SAR) during exposure to 2450 MHz continuous wave (CW) microwaves that affected thermoregulatory behaviour in mice.

2. 2.|A Plexiglas shuttle box was placed inside a waveguide imposed with a temperature gradient. The temperature gradient allowed the mice to select a particular section of the shuttle box which was, presumably, related to their state of thermal comfort. Exposing the mice to 2450 MHz inside the waveguide at SARs of 0–5.3 W kg⁻¹ for 1 h caused no significant change in their preferred ambient temperature.

3. 3.|Increasing SAR from 5.3 to 18.1 W kg⁻¹ caused the animals to shift their position to the cooler end of the shuttle box.

4. 4.|Following termination of microwave exposure animals that had selected a cool ambient temperature returned to the warm side of the shuttle box.

5. 5.|It is concluded that for mice exposed to radiation at 2450 MHz the thermoregulatory behaviour is significantly affected at SARs of 5.3 to 9.9 W kg⁻¹.

The effect of exposure of acetylcholinesterase to 2,450-MHz microwave radiation

The effect of 2,450-MHz pulsed microwave radiation on the enzyme activity of membrane-free acetylcholinesterase was studied while the enzyme was in the microwave field. We found no significant effect of microwave radiation on enzyme activity using a wide variety of power densities, pulse widths, repetition rates, and duty cycles. This suggests that simple, direct modification by microwave energy of acetylcholinesterase structure and enzymic activity is not related to microwave alteration of acetylcholinesterase central nervous system levels.     

Changes in human EEG alpha activity following exposure to two different pulsed magnetic field sequences

The present study investigates the effects of a weak (+/-200 microT(pk)), pulsed, extremely low frequency magnetic field (ELF MF) upon the human electroencephalogram (EEG). We have previously determined that exposure to pulsed ELF MFs can affect the EEG, notably the alpha frequency (8-13 Hz) over the occipital-parietal region of the scalp. In the present study, subjects (n = 32) were exposed to two different pulsed MF sequences (1 and 2, used previously) that differed in presentation rate, in order to examine the effects upon the alpha frequency of the human EEG. Results suggest that compared to sham exposure, alpha activity was lowered over the occipital-parietal regions of the brain during exposure to Sequence 1, while alpha activity over the same regions was higher after Sequence 2 exposure. These effects occurred after approximately 5 min of pulsed MF exposure. The results also suggest that a previous exposure to the pulsed MF sequence determined subjects' responses in the present experiment. This study supports our previous observation of EEG changes after 5 min pulsed ELF MF exposure. The results of this study are also consistent with existing EEG experiments of ELF MF and mobile phone effects upon the brain.     

Testicular function of rats following exposure to microwave radiation

Male Sprague-Dawley rats were exposed for 6 h per day for nine days to pulse-modulated microwave radiation (1.3 GHz, at 1-microseconds pulse width, 600 pulses per second). Exposures were carried out in cylindrical waveguide sections at a mean dose rate of 6.3 mW/g; sham controls were treated similarly and received no irradiation. At time periods corresponding to 0.5, 1.0, 2.0, and 4.0 cycles of the seminiferous epithelium, groups of four sham-irradiated and four irradiated rats were killed and the testes removed for analysis. Net mass of the testes, epididymides, and seminal vesicles; daily sperm production (DSP) per testis and per gram of testis; sperm morphology; and the number of epididymal sperm were determined. There were no statistically significant differences between the sham-irradiated and irradiated groups with respect to any measured variable. In a group of seven surrogate animals of similar body mass, the dose rate of 6.3 mW/g caused a net change in body temperature (via rectal probe) of 1.5 degrees C.     

Combining near‐ and far‐field exposure for an organ‐specific and whole‐body RF‐EMF proxy for epidemiological research: A reference case

A framework for the combination of near‐field (NF) and far‐field (FF) radio frequency electromagnetic exposure sources to the average organ and whole‐body specific absorption rates (SARs) is presented. As a reference case, values based on numerically derived SARs for whole‐body and individual organs and tissues are combined with realistic exposure data, which have been collected using personal exposure meters during the Swiss Qualifex study. The framework presented can be applied to any study region where exposure data is collected by appropriate measurement equipment. Based on results derived from the data for the region of Basel, Switzerland, the relative importance of NF and FF sources to the personal exposure is examined for three different study groups. The results show that a 24‐h whole‐body averaged exposure of a typical mobile phone user is dominated by the use of his or her own mobile phone when a Global System for Mobile Communications (GSM) 900 or GSM 1800 phone is used. If only Universal Mobile Telecommunications System (UMTS) phones are used, the user would experience a lower exposure level on average caused by the lower average output power of UMTS phones. Data presented clearly indicate the necessity of collecting band‐selective exposure data in epidemiological studies related to electromagnetic fields. Bioelectromagnetics 34:366–374, 2013. © 2012 Wiley Periodicals, Inc.     

A circular dichroism study of human erythrocyte ghost proteins during exposure to 2450 MHz microwave radiation

The effect of 2450 MHz microwave radiation on the proteins of human erythrocyte ghosts has been investigated using circular dichroism spectroscopy. A specially constructed waveguide inserted into the spectropolarimeter allowed the continuous recording of optical activity before, during and after microwave irradiation. The data indicate that high levels of microwave radiation (600 mW/g, specific absorption rate) induce decreases in α-helical conformation that may result from both thermal vibrations and increased strain on the intramolecular hydrogen bonds that maintain secondary structure. The latter effect may result from differential intramolecular interactions with the oscillating electric field. Spectrin (bands 1 and 2) isolated from the ghosts was more sensitive to microwave irradiation than intact ghosts, and spectrin-depleted vesicles were the least sensitive. The data, therefore, indicate that the α-helical conformation of spectrin is altered by high levels of microwave radiation.     

Effect of repeated microwave disinfections on bonding of different commercial teeth to resin denture base

doi: 10.1111/j.1741‐2358.2011.00516.x Effect of repeated microwave disinfections on bonding of different commercial teeth to resin denture base Objective: To verify the influence of repeated microwave disinfections on the shear bond strength of two commercial types of teeth to acrylic resin, when the ridge lap surfaces were unmodified, bur abraded, bur grooved or etched by monomer. Material and methods: Eighty specimens (n = 10) were adhered to the tooth ridge lap surface, polymerised in a water bath at 74°C for 9 h. Microwaved specimens were individually immersed in 150 ml of water and submitted to five simulated disinfections in a microwave oven calibrated at 650 W for 3 min. Control specimens were not microwave treated. Shear bond strength tests were performed in an Instron machine with a cross‐speed of 1 mm/min. The fracture load values were transformed into shear bond strength as a function of the bonding area (0.28 cm²). Data were submitted to anova and Tukey’s test (α = 0.05). Fractured areas were classified as adhesive, cohesive (resin or tooth) or mixed failures. Results: Repeated microwave disinfections increased the shear strength of the tooth/resin bond. Mechanical retention in microwaved and non‐microwaved procedures improved the shear bond strength. Conclusions: The different commercial types of teeth influenced shear bond strength values, with Biotone teeth showing the lower values.     

Effects of microwave radiation (340 and 900 MHz) on different structural levels of erythrocyte membranes

By use of fluorescence probes 1-anilinonaphthalene-8-sulfonic acid, 2-toluidinylnaphthalene-6-sulfonate, pyrene, perylene and chemical label phosphatidylethanolamine 2,4,6-trinitrobenzele sulfonic acid, the effect of microwave radiation on the erythrocyte membrane was studied. The studies with the fluorescence probes were carried out on erythrocyte ghosts and with 2,4,6-trinitrobenzene sulfonic acid on whole erythrocytes. The fluorescence was measured during irradiation of the membranes with 340-MHz microwaves at an SAR of 100 W/kg. Trinitrophenylation of phosphatidylethanolamine from whole erythrocytes was performed simultaneously with microwave irradiation at 900 MHz (10 mW/cm2). It was shown that the microwave field decreased lipid viscosity, altered the structural state of lipid-protein contact regions, and decreased the protein shielding of lipids. These changes corresponded to those produced by thermal action of microwaves.     

Fluorescence depolarization studies of red cell membrane fluidity. The effect of exposure to 1.0-GHz microwave radiation

The internal viscosity of human red blood cell membranes was investigated during exposure to continuous wave 1.0-GHz microwave radiation using fluorescence measurements of a lipid seeking molecular probe, diphenylhexatriene. Samples were exposed in a Crawford cell arranged so that fluorescence was measured during microwave exposure; specific absorption rates calculated from electrical measurements were approximately 0.6, 2 and 15 W/kg. Measurements were obtained at selected temperatures between 15 °C and 40 °C and as a function of the duration of exposure at 23 °C. Arrhenius-type plots of the temperature profile data were linear and showed no difference between exposed and control samples. The exposure duration data also showed no difference between exposed and control samples except for a small effect of elevated temperature at the highest exposure. The activation energy for motion of the fluorescent probe in its environment within the membrane lipid was not affected by the application of the microwave energy and no evidence for a lipid phase transition was found. These results indicate that the increased cation efflux from red cells, observed by others at certain transition temperatures during microwave exposure, was more likely to have been caused by alteration of the membrane bound protein than by changes in the lipid constituents of the red cell membrane.     

Effect of continuous-wave and amplitude-modulated 2.45 GHz microwave radiation on the liver and brain aminoacyl-transfer RNA synthetases of in utero exposed mice

Investigations have been carried out concerning the effects of microwave (MW) exposure on the aminoacyl-transfer ribonucleic acid (tRNA) synthetase of the progeny of females that were exposed during their entire period of gestation (19 days). The changes caused by continuous-wave (CW) and amplitude-modulated (AM) MW radiation have been compared. CFLP mice were exposed to MW radiation for 100 min each day in an anechoic room. The MW frequency was 2.45 GHz, and the amplitude modulation had a 50 Hz rectangular waveform (on/off ratio, 50/50%). The average power density exposure was 3 mW/cm², and the whole body specific absorption rate (SAR) was 4.23 ± 0.63 W/kg. The weight and mortality of the progeny were followed until postnatal day 24. Aminoacyl-tRNA synthetase enzymes and tRNA from the brains and livers of the offspring (461 exposed, 487 control) were isolated. The aminoacyl-tRNA synthetase activities were determined. The postnatal increase of body weight and organ weight was not influenced by the prenatal MW radiation. The activity of enzyme isolated from the brain showed a significant decrease after CW MW exposure, but the changes were not significant after 50 Hz AM MW exposure. The activity of the enzyme isolated from liver increased under CW and 50 Hz modulated MW. © 1996 Wiley-Liss, Inc.     

Localized effects of microwave radiation on the intact eye lens in culture conditions

A novel experimental system was used to investigate the localized effects of microwave radiation on bovine eye lenses in culture for over 2 weeks. Using this setup, we found clear evidence that this radiation has a significant impact on the eye lens. At the macroscopic level, it is demonstrated that exposure to a few mW at 1 GHz for over 36 h affects the optical function of the lens. Most importantly, self-recovery occurs if the exposure is interrupted. At the microscopic level, close examination of the lens indicates that the interaction mechanism is completely different from the mechanism-causing cataract via temperature increase. Contrary to the latter's effect, that is particularly pronounced in the vicinity of the sutures and it is assumed to be a result of local friction between the edges of the fibers consisting the lens. Even if macroscopically the lens has recovered from the irradiation, microscopically the indicators of radiation impact remain.     

Tuning,coupling and matching of a resonant cavity in microwave exposure system for biological objects

A new microwave exposure system for biological experiments with well-defined exposure conditions and improved control of the exposure parameters consisting of variable frequency power source, coaxial to waveguide transition, matching network and single-mode resonant cavity with movable shorting plunger was fabricated and characterized. The introduction of a biological sample into a resonant cavity has a large impact on its field configuration and port impedance. As such, the properties, geometry and position of the biological sample become a part of the electrical properties of the microwave circuit. With that change, the electrical properties of the resonant cavity, such as impedance, quality factor and resonant frequency, also change. In this study, an appropriate coupling system with effective power transfer and an algorithm to tuning and coupling of resonant cavity in resonance before and after the introduction of biological sample have been proposed. This procedure will lead to a known dose distribution within the biological sample and allow a better comparison with other studies. Coupling of the electromagnetic energy into a resonant cavity was experimentally investigated. Graphical representation of cavity impedance in case of undercoupled, critically coupled and overcoupled cavity has been presented. Critical coupling of an empty resonant cavity has been accomplished at voltage standing wave ratio (VSWR) 1.01, at resonance frequencies 900 and 947.5 MHz. Critical coupling with the introduction of a biological sample has been accomplished at VSWR ≤ 1.07 for frequency bandwidth 1 MHz and VSWR ≤ 1.5 for frequency bandwidth up to 5 MHz with central frequency 947.5 MHz.     

微波辐射对肾小管上皮细胞的影响以及金雀异黄素对其保护作用

目的：观察微波辐照对人近端肾小管上皮细胞（HKC）的影响及金雀异黄素对其的保护作用。方法：HKC分为对照组、微波辐照组、金雀异黄素组（n=6）。金雀异黄素组在辐照前2 h用含30μmol/L金雀异黄素的DMEM培养基进行预培养。辐照后24 h留取上清进行乳酸脱氢酶（LDH）、β-N-乙酰氨基葡萄糖苷酶（NAG）活性及丙二醛（MDA）、超氧化物歧化酶（SOD）活性检测。Hoechst 33258染色观察细胞凋亡情况。结果：与对照组比较,微波辐照组上清NAG、LDH活性明显增加（P < 0.01）,金雀异黄素预处理组则较微波辐照组明显下降（P < 0.01）;微波辐照组上清活性也较对照组明显增加（P < 0.01）。Hoechst 33258染色显示,微波辐照可导致较多量的细胞凋亡,而应用金雀异黄素预处理后细胞凋亡的比例均大大减少。微波辐照可大大提高HKC细胞中的MDA含量,SOD活性降低（P< 0.01）,应用金雀异黄素预处理后MDA的含量无明显降低,SOD的活性明显增大（P < 0.01）。结论：微波辐照可导致人近端肾小管上皮细胞出现功能损伤,金雀异黄素对其具有一定的保护作用,可能与其减轻氧化应激损伤、减少细胞凋亡有关。     

Effect of chronic microwave radiation on T cell-mediated immunity in the rabbit

Experiments were conducted to elucidate the effects of chronic low power-level microwave radiation on the immunological systems of rabbits. Fourteen male Belgian white rabbits were exposed to microwave radiation at 5 mW/cm², 2.1 GHz, 3 h daily, 6 days/week for 3 months in two batches of 7 each in specially designed miniature anechoicchambers. Seven rabbits were subjected to sham exposure for identical duration. The microwave energy was provided through S band standard gain horns connected to a 4K3SJ2 Klystron power amplifier. The first batch of animals were assessed for T lymphocyte-mediated cellular immune response mechanisms and the second batch of animals for B lymphocyte-mediated humoral immune response mechanisms. The peripheral blood samples collected monthly during microwave/sham exposure and during follow-up (5/14 days after termination of exposures, in the second batch animals only) were analysed for T lymphocyte numbers and their mitogen responsiveness to ConA and PHA. Significant suppression of T lymphocyte numbers was noted in the microwave group at 2 months (P<0.01, % 21.5%) and during follow-up (P<0.01, % 30.2%). The first batch animals were initially sensitised with BCG and challenged with tuberculin (0.03 ml) at the termination of microwave irradiation/sham exposure and the increase in foot pad thickness ( mm), which is a measure of T cell-mediated immunity (delayed type hypersensitivity response, DTH) was noted in both the groups. The microwave group revealed a better response than the control group (%+12.4 vs.+7.54). The animals were sacrified and the tissue T lymphocyte counts (spleen and lymph node) were analysed. No significant variation was observed in the tissue T lymphocyte counts of microwave-irradiated rabbits. From these results it is speculated that the T lymphocytes are sequestered to various lymphoid organs under the influence of microwaves. A sub-population of T cells known as T helper cells (mediating DTH response) are probably not affected by microwave radiation. It is clear from our experiments that although chronic microwave radiation at 5 mW/cm² leads to suppression of peripheral T lymphocyte numbers, there is no concomitant functional impairment of these cells as evidenced by functional assays.     

Prolonged microwave irradiation of rats: Effects on concurrent operant behavior

Two measures of performance were used to study the effects of pulse-modulated microwave radiation (PM MWR) on schedule-controlled operant behavior of rats: 1) cued (S^D), fixed-ratio (FR) bar pressing for food reinforcement; and 2) noncued (S^d) bar pressing in the absence of food reinforcement. The animals were irradiated and the behavioral data were obtained concurrently, during daily three-hour sessions, five days per week for six to nine weeks. Each experiment began with a two to three-week baseline interval of sham irradiation; a two to three-week interval of sham irradiation followed the irradiation phase. The irradiated animals were exposed to 1.3-Ghz PM MWR (pulse width of 1 microsecond at 600 pulses per second) at whole-body, average specific absorbed-dose rates of from 1.5–6.7 mW/g. Control and irradiated animals were tested in identical, cylindrical waveguide exposure/behavioral assemblies; different groups of irradiated and sham-irradiated animals were used for each dose rate. At 1.5 mW/g, the levels of S^D operant responding by control and irradiated animals were comparable, and showed similar progressive diminutions over the course of each daily session. S^d operant responding was more variable, but again comparable, with both groups showing similar, progressive declines in rate of responding during each session. At 3.6 mW/g, no specific effects on S^D operant response rates were observed. However, there was an initial and transient increase in the rate of extinction of S^d responding. At 6.7 mW/g, S^D response rates were slightly reduced, whereas there was a major reduction in noncued (S^d) operant responding followed by a sharp rebound during the first post-MWR week. This marked reduction in S^d operant responding at MWR onset was in contrast to the relative stability and persistence of FR responding for food reinforcement.     

The exposure level of heavy metals at four different locations near Gan-Ning-Meng reaches of the Yellow River,China

Hair, water, and sediment samples (n = 69, 27, and 24, respectively) were collected at four locations (P1–P4) along the Yellow River Gan-Ning-Meng (GNM) reaches, China. Total elemental contents of Cd, Cr, Cu, Fe, Mn, Pb, and Zn were determined using inductively coupled plasma mass spectroscopy (ICP-MS) to investigate their distribution and exposure levels in the different media. Results showed that trace metals had widely spatial variability in water and hair samples. There were the highest levels of mean concentrations of Cd, Cu, Fe, Mn, Pb, and Zn (geometric mean, GM = 0.22, 17, 65, 3.0, 4.9, and 170 μg/g, respectively) in residents' hairs living at P2. Most of the hair donors in this study showed high concentrations of Cr when compared with the literature. Differences could be distinguished for Mn (p = 0.001) and Fe (p = 0.001) with gender, and for Cr (p = 0.021), Zn (p = 0.003), and Pb (p = 0.035) with age, respectively. The pollution assessments revealed an unpolluted degree in filtered water and a moderately polluted degree for Cd in sediments at P1–P4. Correlation analysis showed significant correlations between hair and sediment samples for Cr and Mn. This paper provides basic and useful information in facing public and environmental health challenges in the GNM sections of the Yellow River.     

Setup and dosimetry for exposure of human skin in vivo to RF-EMF at 900 MHz

The aim of this study was a dosimetrical analysis of an experimental setup used in the exposure of 10 female volunteers to GSM 900 radiation. The exposure was carried out by irradiating a small region of the right forearms of the volunteers for 1 h, after which biopsies were taken from the exposed skin for protein analysis. The source of irradiation was a half-wave dipole fed with a computer controlled GSM phone. The specific absorption rate (SAR) induced in the skin biopsy was assessed by computer simulations. The numerical model of the arm consisted of a muscle tissue simulating cylinder covered with thin skin (1 mm) and fat (3 mm) layers. The simulation models were validated by measurements with a homogeneous cylindrical liquid phantom. The average SAR value in the biopsy was 1.3 W/kg and the estimated uncertainty +/-20% (K = 2). The main source of error was found to be variations in the distance of the forearm from the dipole (10 +/- 1 mm). Other significant sources of uncertainty are individual variations of the fat layer and arm thicknesses, and the uncertainty of radio frequency (RF) power measurement.