Van Leeuwen GM et al. · 1999
Researchers evaluated 3D temperature rise in a realistic head model induced by a mobile phone. The power distributions had a maximum averaged SAR over a 10 g volume of approximately 1.6 W kg(-1). Simulations showed a maximum brain temperature rise of 0.11 degrees C for a 0.25 W antenna with indefinite exposure, and the authors noted that temperature rises are far too small to have lasting effects.
Paul Raj R, Behari J, Rao AR · 1999
The effect of exposing rats to amplitude-modulated radiofrequency radiation (112 MHz modulated to 16 Hz) during development and growth was examined. Wistar rats 35 days old exposed at 1.0 mW/cm2 (SAR 0.75 W/kg) for 35 days showed enhanced ornithine decarboxylase activity and Ca2+ efflux in brain.
Borbely et al. · 1999
Researchers exposed healthy young subjects during an entire night-time sleep episode to a 900 MHz electromagnetic field at a maximum specific absorption rate of 1 W/kg. The exposure schedule consisted of alternating 15-min on-15-min off intervals. Compared with a control night with sham exposure, the amount of waking after sleep onset was reduced from 18 to 12 min, and EEG spectral power in non-rapid eye movement sleep was increased. The researchers concluded that pulsed high-frequency EMF in the range of radiotelephones may promote sleep and modify the sleep EEG.
Schonborn F, Burkhardt M, Kuster N · 1998
In order to investigate the differences in absorption between adults and children due to their differing anatomies, simulations were performed using head phantoms based on MRI scans of an adult and two children aged 3 and 7 years. Ten different tissue types were distinguished and all simulations were performed using a commercial code based on the finite integration technique. The differences in absorption were investigated for the frequencies of 900 MHz and 1,800 MHz using 0.45 lambda dipoles instead of actual mobile phones. The results revealed no significant differences in the absorption of electromagnetic radiation in the near field of sources between adults and children.
Malyapa RS et al. · 1998
Researchers exposed male Sprague-Dawley rats to 2450 MHz continuous-wave microwaves for two hours at 1.2 W/kg specific absorption rate. No significant differences in DNA damage were found between sham-exposed and irradiated rats in either the cerebral cortex or hippocampus, regardless of euthanasia method. Rats euthanized by CO2 asphyxia showed more intrinsic DNA damage and greater experiment-to-experiment variation than those euthanized by guillotine. The authors concluded that guillotine euthanasia is the most appropriate method for DNA damage studies. The study did not confirm previous reports of DNA damage from 2450 MHz microwave exposure.
Freude, G, Ullsperger, P, Eggert ,S, Ruppe, I · 1998
Researchers studied the influence of electromagnetic fields emitted by cellular phones on preparatory slow brain potentials in healthy male subjects using two experimental tasks. Both tasks were performed with and without EMF exposure in counterbalanced order. Subjects' performance did not differ between exposure conditions, but EMF exposure significantly decreased slow brain potentials at central and temporo-parieto-occipital regions during the visual monitoring task and did not affect the Bereitschaftspotential in the finger movement task.
Eulitz, C, Ullsperger, P, Freude, G, Elbert ,T · 1998
The study aimed to investigate how mobile phones modulate response patterns of human brain activity. The researchers found that pulsed high-frequency electromagnetic fields from mobile phones alter induced but not evoked brain activity in higher frequency bands during processing of task-relevant target stimuli, with no effect for irrelevant standard stimuli. The authors suggest that PEMF exposure may provide a means to systematically alter pattern fluctuations in neural mass activity.
Ding G, Xie X, Zhang L et al. · 1998
Researchers studied the distribution of nitric oxide synthase (NOS) expression in the hippocampus and cerebellum of rats after exposure to electromagnetic pulse (EMP). The number of NOS-positive neurons and staining intensity in the hippocampus decreased at 1.5 and 24 hours after exposure. At 48 hours, the number of NOS-positive neurons returned to control levels, but staining intensity remained lower. NOS expression in the cerebellum showed no obvious changes. The authors suggest that decreased hippocampal NOS expression relates to learning and memory obstruction after EMP exposure.
Walters TJ et al. · 1998
Researchers measured hypothalamic, cortical, tympanic, and rectal temperatures in rats exposed to 2.06 GHz microwave radiation at two power densities. The high-power density was 1700 mW/cm² with specific absorption rates of 1224 W/kg in hypothalamus and 493 W/kg in cortex, while the low-power density was 170 mW/cm² with SARs of 122.4 W/kg and 49.3 W/kg. During high-power exposure, the hypothalamic temperature rose significantly faster than cortical or rectal temperatures, whereas low-power exposure produced more uniform heating. For comparison, warm-water immersion produced uniform heating, while warm ambient exposure and exercise maintained the pre-existing temperature gradient between hypothalamus and cortex.
Grigor'ev IuG, Stepanov VS · 1998
Researchers investigated how prior low-level electromagnetic field exposure affects memory formation (imprinting) in chicks. EMF at power densities from 0.4 to 10 mW/cm2 was found to potentially influence the forming of memory (imprinting). The study showed the possibility of EMF-modulated information being fixed in the embryonic brain during the natal period and conserved after birth.
Behari J, Kunjilwar KK, and Pyne S · 1998
Researchers studied the effect of low-level amplitude-modulated radiofrequency radiation on Na+–K+-ATPase activity in the brains of developing male Wistar rats aged 23 days. Rats were exposed to carrier wave frequencies of 147 MHz and its sub-harmonic frequencies 73.5 and 36.75 MHz, amplitude modulated at 16 and 76 Hz, for 30–35 days at 3 hours per day. Na+–K+-ATPase activity increased by around 19–20% in rats exposed with amplitude modulation at 16 Hz, and by around 15–16% in rats exposed with amplitude modulation at 76 Hz, compared to controls. The researchers concluded that the effect on Na+–K+-ATPase activity was insensitive to the carrier wave frequencies under investigation.
Unknown authors · 1997
Researchers exposed ten patients with perceived electrical hypersensitivity and ten healthy controls to amplitude-modulated light. The sensitivity of the brain to this type of visual stimulation was tested using electroretinography and visual evoked potentials. Patients had higher cortical response amplitudes at all stimulation frequencies, but retinal responses did not differ.
Salford LG, Brun A, Persson BRR · 1997
Researchers used Fischer 344 rats of both sexes with implanted glioma cells (RG2 and N32) in a matched-pair design. Starting on day 5 after inoculation, rats were exposed for 7 hours a day, 5 days a week for 2–3 weeks to 915 MHz continuous or pulse-modulated microwaves. The study found no significant difference in tumour size between exposed and control animals. Tumour size was estimated as the volume of an ellipsoid after histopathological examination of all brains.
Persson BRR, Salford LG, Brun A · 1997
Researchers studied blood-brain barrier permeability in Fischer 344 rats of both sexes exposed to radio frequency electromagnetic fields. The exposure used 915 MHz microwaves delivered as either pulse-modulated or continuous wave signals. The rate of pathological leakage rose from 0.17 in controls to 0.39 across all exposed rats, a highly significant difference. Continuous wave exposure produced a higher rate of pathological rats (0.50 ± 0.07) than pulse-modulated exposure (0.35 ± 0.03), and that difference was also statistically significant.
Vorobyov VV, Galchenko AA, Kukushkin NI, Akoev IG · 1997
Researchers studied averaged EEG frequency spectra in eight unanesthetized adult male rats with chronically implanted electrodes in symmetrical somesthetic areas during intermittent exposure to a weak 945 MHz microwave field amplitude-modulated at 4 Hz. Hemispheric asymmetry showed power decreases in the 1.5-3 Hz range on the left and in the 10-14 and 20-30 Hz ranges on the right hemisphere. No differences between control and exposure were found in averaged spectra over 10 or 1 minute periods. However, significant elevations of EEG asymmetry in the 10-14 Hz range occurred during the first 20 seconds after most microwave field onsets when spectra were averaged every 10 seconds.
Pu, JS, Chen, J, Yang, YH, Bai, YQ · 1997
Mason PA et al. · 1997
Researchers measured extracellular amino acid concentrations in the hypothalamus and caudate nucleus of rats using in vivo microdialysis before and during exposure to RFR. Rats were exposed to 5.02 GHz radiation (10 microseconds pulse width, 1000 pulses/s) for 40 minutes while brain temperatures were maintained at approximately 41.2 and 41.7 degrees C. Aspartic acid, serine, and glycine concentrations increased significantly in both regions during exposure. Glutamic acid and glutamine changes were not statistically significant.
Fritze K et al. · 1997
Researchers studied the effect of GSM microwave exposure on gene activity in the rat brain by measuring messenger RNAs of hsp70, c-fos, c-jun, and GFAP using in situ hybridization histochemistry. The study used specific absorption rates of 0.3 W/kg, 1.5 W/kg, and 7.5 W/kg. Immediately after exposure, slight hsp70 messenger RNA induction was found in the cerebellum and hippocampus at 7.5 W/kg, but not at lower intensities. At 24 hours and seven days after exposure, no lasting protein changes, altered glial marker expression, or increased cell proliferation were observed.
Lai, H, Singh, NP, · 1997
Researchers investigated the effects of microwave exposure on DNA strand breaks in rat brain cells. They found that treating rats with either melatonin or the spin-trap compound PBN immediately before and after radiofrequency electromagnetic radiation exposure blocked the DNA strand breaks. Because both substances are free radical scavengers, the researchers hypothesized that free radicals are involved in the radiofrequency electromagnetic radiation-induced DNA damage.
Lai H, Singh NP · 1997
Researchers investigated whether melatonin and the spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) could block the effect of magnetic fields on brain cell DNA. Rats were injected with melatonin or PBN immediately before and after two hours of exposure to a 60-Hz magnetic field at an intensity of 0.5 mT. Both drug treatments blocked the magnetic field-induced DNA single- and double-strand breaks in brain cells, as measured by a microgel electrophoresis method.
Lai H, Carino MA, Singh NP · 1997
Researchers exposed rats to 2450 MHz pulsed radiofrequency radiation at a power density of 2 mW/cm2 for 2 hours and then measured DNA double strand breaks in brain cells. The RFR exposure significantly increased DNA double strand breaks in rat brain cells, and the effect was partially blocked by naltrexone treatment. The researchers concluded that endogenous opioids play a mediating role in RFR-induced DNA strand breaks in brain cells of the rat.
Unknown authors · 1996
The ferromagnetic transduction model proposes that biogenic magnetic particles in the brain coupled to mechanosensitive ion gates may mediate interactions with environmental magnetic fields. The authors show that pulsed fields, square waves, and DC fields could force open these membrane gates long enough to disrupt normal neurophysiological processes. The extended model may explain central nervous system effects in epileptic patients exposed to low frequency square wave and DC magnetic fields.
Grayson JK · 1996
A nested case-control study investigated electromagnetic field exposures and brain tumor risk in the US Air Force. Cumulative extremely low frequency and radiofrequency/microwave exposures were estimated from a job-exposure matrix, and ionizing radiation exposures came from personal dosimetry records. Nonionizing electromagnetic field exposure showed a small excess risk with extremely low frequency OR 1.28 (95% CI 0.95-1.74) and radiofrequency/microwave OR 1.39 (95% CI 1.01-1.90), while ionizing radiation had OR 0.58 (95% CI 0.22-1.52). Military rank was consistently associated with brain tumor risk, with officers having OR 2.11 (95% CI 1.48-3.01) versus enlisted men and senior officers OR 3.30 (95% CI 1.99-5.45) versus all others.
Andersson B, Berg M, Arnetz BB, Melin L, Langlet I, Lidén S. · 1996
Seventeen patients were randomly assigned to a treatment group or a waiting-list control group in a pretest-posttest control group design. Patients participated in double-blind provocation tests before and after treatment. Subjective symptom ratings and blood samples for stress-related variables were collected. The experimental group reduced disability evaluations more than the control group, but no significant between-group differences were found in psychophysiological measures or subjective reactions to provocation. The provocation test concluded that alleged hypersensitive patients did not react to electromagnetic fields.
Violanti JM, Marshall JR · 1996
Talking more than 50 minutes per month on a cellular phone in a vehicle was associated with a 5.59-fold increased risk of a traffic accident. Combined use of cellular phones with motor and cognitive activities while driving was also associated with increased accident risk. The authors cautioned that the study had a small sample, showed only statistical associations, and did not conclude that talking on cellular phones while driving is inherently dangerous.
