Krylov IN, Iasnetsov VV, Dukhanin AS, Pal'tsev IuP · 1993
Researchers exposed rats to microwaves at 2375 MHz with a power density of 1 mW/cm2 and found that this induced retrograde amnesia. The study found roles for opioidergic, benzodiazepine, GABAergic, and cholinergic components in the memory-impairing effects of microwaves. Piracetam and oxiracetam each prevented the negative effects of microwaves on memory processes in the rats.
Unknown authors · 1992
The study used an ultrasensitive superconducting magnetometer to detect ferromagnetic material in various human brain tissues. High-resolution electron microscopy identified the minerals as belonging to the magnetite-maghemite family, with crystal morphologies resembling those produced by magnetotactic bacteria and fish. The measurements imply at least 5 million single-domain crystals per gram in most brain tissues and over 100 million per gram in the pia and dura.
Fukui Y, Hoshino K, Inouye M, Kameyama Y · 1992
Researchers exposed pregnant mice to 2.45 GHz microwave radiation for 15 or 20 minutes on day 13 of gestation. Pyknotic cell incidence in the ventricular zone was 1.83% after 15 minutes and 3.06% after 20 minutes of microwave exposure. Microwave radiation for 20 minutes produced effects comparable to immersion in 42°C hot water for 15 minutes. Brain weight was significantly lower and neuron density higher in the 20-minute exposure group compared to controls. The researchers concluded that microwave radiation at the tested dose mainly has a thermal effect.
Lai H, Carino MA, Horita A, Guy AW · 1992
Researchers exposed rats to single 45-minute and repeated daily 45-minute microwave sessions at 2450 MHz, 1 mW/cm², with a whole-body SAR of 0.6 W/kg. After a single exposure, receptor concentration increased in the cerebral cortex but not in the hippocampus or cerebellum. No significant change in binding affinity of the receptors was observed in any of the brain regions studied. After repeated exposures, no significant change in receptor concentration was found in the cerebral cortex. Handling and exposure procedures did not significantly affect benzodiazepine receptors.
Inaba R, Shishido K, Okada A, Moroji T. · 1992
Ray S, Behari J · 1990
Researchers studied the effects of exposure to sublethal levels of microwaves. Young albino rats of both sexes were exposed for 60 days to 7.5-GHz microwaves at 0.6 mW/cm2 for 3 hours daily. The exposed animals tended to eat and drink less and showed a smaller gain in body weight. Some hematological parameters and organ weights were significantly different in exposed rats. The authors proposed that a nonspecific stress response mediated through the central nervous system caused the changes.
Neubauer C, Phelan AM, Kues H, Lange DG · 1990
Researchers exposed male albino rats to 2.45-GHz microwaves with 10-microseconds pulses at 100 pps. Exposure at 10 mW/cm2 for 30 to 120 minutes increased tracer uptake through the blood-brain barrier. The uptake depended on both power density and exposure duration. At 5 mW/cm2, a 15-minute exposure had no effect. Pretreating rats with colchicine nearly completely blocked the microwave-induced uptake.
C. F. Blackman et al. · 1980
Researchers exposed brain tissue from chicks to 147-MHz radiation amplitude modulated at 16 Hz or 9 Hz for 20 minutes. Control exposures to unmodulated carrier at 0.83 nW/cm² and to zero field-strength produced no significant differences between exposed and sham groups. Temperature control experiments showed efflux was 9% lower at 32°C and 15% higher at 41°C compared to 37°C.
Joseph K. Kielman et al. · 1980
The authors reviewed experimental results from investigators worldwide on radiofrequency and microwave radiation bioeffects. Absorption of electromagnetic energy between 300 kHz and 300 GHz depends on frequency, organism geometry, and tissue dielectric properties. At power densities above 10 mW/cm2, energy dissipation can cause thermogenesis. Below 10 mW/cm2, core temperature and metabolic rate remain unchanged but biological effects are observed, including alterations in blood-brain barrier, neurotransmitter release, EEG, heart rate, immunocompetence, hematopoiesis, neuroendocrine function, and behavior. Subjective human effects such as headaches, weakness, and auditory response have also been reported.
Sol M. Michaelson · 1980
Some reports suggest low power density microwaves affect neural and immunologic function, but many studies have methodological inadequacies. The review finds no satisfactory evidence of genetic effects at low to modest power densities, and recent studies confirm exposures below 10 mW/cm² are not mutagenic. Developmental abnormalities are attributed to hyperthermia, and no serious effects are expected below 10 mW/cm² under usual conditions. Behavioral studies show performance suppression with a threshold power density of 5 to 50 mW/cm² depending on exposure parameters.
KENNETH R. FOSTER et al. · 1979
Between 0-01 and ~1 GHz the permittivity decreased and conductivity increased as a power law of frequency. Above 1 GHz the conductivity increased quadratically with frequency due to dipolar reorientation of free water molecules, with an apparent rotational relaxation frequency of 21-24 GHz at 37 °C. The authors provided empirical equations for the dielectric properties of average brain tissue at 37 °C for theoretical microwave absorption studies.
Henry S. Ho, William P. Edwards, Howard Bassen · 1979
Researchers measured internal electric field distributions in phantom human heads exposed to leakage radiation from 2450 MHz and 915 MHz microwave ovens. The phantom heads were made from actual adult and child skulls filled with dielectric materials matching the electrical properties of muscle or brain. For 5 mW/cm² leakage at 2450 MHz, the maximum equivalent dose rate was 9.6 W/kg in the adult phantom and 14.6 W/kg in the child phantom. For 5 mW/cm² leakage at 915 MHz, the maximum equivalent dose rate was 3.0 W/kg in the adult phantom and 5.3 W/kg in the child phantom.
Carl H. Sutton, Frederick B. Carroll · 1979
Researchers used Sprague-Dawley male rats to study the tolerance of the blood-brain barrier to microwave irradiation at 2450 MHz. Horseradish peroxidase was administered 30 minutes before sacrifice to assess barrier disruption, and brains were analyzed after perfusion. In normothermic rats, the barrier was disrupted after 10 minutes at 45°C, 15 minutes at 42°C, and 60 minutes at 40°C; in hypothermic rats, disruption occurred after longer durations at the same temperatures.
Charles L. Sheridan et al. · 1979
The longevity study of mice exposed in utero to near-lethal 2450-MHz microwave radiation is in its third year with mortality rising in both groups. Spontaneous tumors appeared in two control mice (n=81) but not in radiated mice (n=83), a difference too narrow to exclude chance. Acute studies in anesthetized rats, guinea pigs, and rabbits showed that brief near-lethal 2450-MHz exposures produced whole-body temperature rises of 4.5 to 12 K and altered thermal distributions, with the brain stem appearing thermally privileged. Twelve pilot studies were completed to optimize microwave hyperthermia as adjuvant treatment for experimentally induced glioblastoma in rats.
Ohno, K., Pettigrew, K.D., Rapoport, S.I. · 1978
They measured cerebrovascular permeability-area products for 14C-sucrose in 5 brain regions. Mean PA values were similar across sham, 1 mW /cm², and 10 mW/cm² groups. The authors concluded that an effect of microwave treatment on barrier permeability cannot be concluded.
S. M. Bawin, A. Sheppard, W. R. Adey · 1978
Albert, E.N. · 1978
Researchers exposed adult Wistar rats and Chinese hamsters to continuous-wave microwave irradiation at 2450 and 2800 MHz at 10 mW/cm² for 2 hours. Horseradish peroxidase was injected intravenously to identify brain areas with increased blood-brain barrier permeability. Electron microscopy revealed endothelial cells flooded with peroxidase, swollen astrocytic end feet, myelin figures in dendrites, membranous proliferation in dendrites, and platelet microthrombi in capillaries. Light microscopy showed edematous neuropil surrounding leaky vessels.
Unknown authors · 1978
Evoked potentials measured inside and outside the magnet were essentially the same, and the latency of fast and slow waves from limb to brain was not changed by the magnetic field. Heart rate was lower inside the magnet, while blood pressure results showed opposite directions in the two monkeys. Noticeable changes in blood hematology and chemistry can be attributed to the trauma caused by the implantation of the cortical electrodes. From the tests which were performed, as described above, we conclude that there were no observable effects in the two monkeys.
R. H. Lenox, J. L. Meyerhoff, O. P. Gandhi, H. L. Wray · 1977
Researchers varied microwave exposure configuration and output power to inactivate brain enzymes in rats. They studied the rate of metabolic inactivation in various brain regions by measuring cyclic AMP and phosphodiesterase activity. Exposure times needed to stabilize cyclic AMP levels differed among the hypothalamus, cortex, and cerebellum. Cyclic AMP levels in some regions decreased when inactivation was more rapid.
R. A. MOIDEL, S. K. WOLFSON, JR., R. G. SELKER, S. B. WEINER · 1976
Peter A. Neukomm · 1976
Most telemetry equipment operates between 10 and 1000 MHz with radiated power from a few microwatts to approximately 2 W. Hot spots in animal brains show heating potential 10 to 15 times higher than predicted by the RAC method.
James H. Merritt, Richard H. Hartzell, James W. Frazer · 1976
Unknown authors · 1976
Researchers used whole brain homogenate from unsexed adult Sprague-Dawley rats. For atropine, the bound-to-free ratio fell from near 2 in controls to near 1 in irradiated samples. For acetylcholine, irradiated samples showed a tendency toward lower ratios, but insufficient data prevented a significance test.
James H. Merritt, James W. Frazer · 1975
Mice were exposed to 19 MHz radiofrequency radiation and then euthanized by microwave-heating brain inactivation. There were no significant differences in any neurotransmitters or metabolites when microwave controls were compared to either the E-field or H-field groups. Microwave controls had significantly higher brain content of 5-hydroxyindole acetic acid, serotonin, norepinephrine, and dopamine than conventional controls.
A. P. Krueger, E. J. Reed · 1975
Researchers exposed young mice to simulated ELF electromagnetic fields at 45 Hz and 75 Hz at 100 V/m and measured growth rate, serotonin metabolism, and susceptibility to influenza virus. No significant difference in growth rate was found between exposed and control mice across experiments lasting 12 to 26 days. Four separate influenza challenge tests at 75 Hz and 100 V/m found no evidence of altered resistance using cumulative mortality rates and LD50 titers.
