Seaman RL, Beblo DA · 1992
Researchers presented single 1.25-GHz microwave pulses of 0.8- to 1.0-microseconds duration to four rats 100 ms before a startle-inducing acoustic stimulus. At a lower energy dose of 22-43 mJ/kg per pulse, the mean startle latency was longer and the mean amplitude was smaller compared to control responses to acoustic stimuli alone. At a higher energy dose of 59-107 mJ/kg per pulse, the mean latency and amplitude were not statistically different from controls.
Bolshakov MA, Alekseev SI · 1992
Researchers recorded spontaneous electrical activity and ionic currents of Lymnea stagnalis neurons during exposure to a 900-MHz field using modified microelectrode and voltage-clamp techniques. When subjected to pulsed waves, rapid burst-like changes in the firing rate of neurons occurred at SARs of a few W/kg. The effect was dependent on modulation but not on modulation frequency, with a threshold SAR near 0.5 W/kg. Continuous-wave radiation had no effect on the firing rate pattern at the same SAR. Mediator-induced activation of acetylcholine, dopamine, serotonin, or GABA receptors was not altered during either exposure, indicating these receptors were not responsible for the bursting effect.
Saffer JD, Profenno LA · 1992
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.
Fucic A, Garaj-Vrhovac V, Skara M, Dimitrovic B · 1992
Researchers used the micronucleus assay with a new mathematical approach to separate clastogenic from aneugenic activity of vinyl chloride monomer, X-rays, and microwaves on human somatic cells. Comparison of micronucleus size distributions in lymphocytes from exposed humans showed X-rays and microwaves were preferentially clastogens while vinyl chloride monomer showed aneugenic activity as well. The authors noted that microwaves possess some mutagenic characteristics typical of chemical mutagens.
Enin LD, Akoev GN, Potekhina IL, Oleiner VD · 1992
The study aimed to investigate the effect of extremely high-frequency electromagnetic radiation on skin sensory endings in albino rats. Researchers recorded impulse activity from solitary fibers of the tibial nerve and found that receptor units responded to mechanical stimulation of the skin. Irradiation with low-intensity millimeter-band fields at 55.61 and 73 GHz reduced receptor unit sensitivity to mechanical stimulation. Half of the receptor units stopped responding 25 minutes after irradiation, while the other half continued responding after 35 minutes but with a significantly changed response character.
Dutta SK, Das K, Ghosh B, Blackman CF · 1992
Researchers examined the impact of radiofrequency radiation exposure on acetylcholinesterase activity. Neuroblastoma cells (NG108) exposed for 30 minutes to 147-MHz radiation amplitude-modulated at 16 Hz demonstrated enhanced acetylcholinesterase activity. The authors concluded that radiofrequency radiation affects both calcium-ion release and acetylcholinesterase activity in nervous system-derived cells in culture in a common dose-dependent manner.
Phelan AM, Lange DG, Kues HA, Lutty GA · 1992
Researchers exposed B16 melanoma cells to 2.45-GHz pulsed microwaves at 10 mW/cm² for 1 hour and measured membrane ordering using electron paramagnetic resonance. The exposure shifted the cell membrane from a more fluid-like phase to a more solid, ordered state. Similar membrane ordering occurred in melanin-reconstituted liposomes, but not in amelanotic cells or liposomes without melanin. Superoxide dismutase inhibited the microwave-induced ordering, implicating oxygen radicals as a cause.
Maillefer RH, Quock RM · 1992
Male Swiss Webster mice were exposed to 10, 15, and 20 mW/cm2 RFR at 2450 MHz for 10 minutes at SARs of 23.7, 34.6, and 45.5 W/kg, then tested in the abdominal constriction paradigm. Confinement alone did not appreciably alter body temperature but appeared to induce stress-associated analgesia that was not blocked by naltrexone. RFR exposure raised body temperature and further increased analgesia in an SAR-dependent manner. The high SAR-induced analgesia was blocked by naltrexone, but the hyperthermia was not.
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.
Lai H, Carino MA, Horita A, Guy AW, · 1992
Researchers investigated which opioid receptor subtypes mediate a microwave-induced decrease in central cholinergic activity in rats. Rats were pretreated with specific antagonists of mu, delta, and kappa opioid receptors before exposure to microwaves. All three receptor subtypes were involved in the decrease in cholinergic activity in the hippocampus.
Kues HA et al. · 1992
Researchers exposed anesthetized monkeys to pulsed 2.45 GHz microwaves after topical treatment with timolol maleate or pilocarpine. Drug pretreatment lowered the power-density threshold for corneal endothelial lesions and increased iris vascular permeability from 10 to 1 mW/cm². Effects occurred at an average SAR of 0.26 W/kg and were confirmed with specular microscopy, fluorescein angiography, and horseradish peroxidase tracer techniques.
Inaba R, Shishido K, Okada A, Moroji T. · 1992
Czerska EM, Elson EC, Davis CC, Swicord ML, Czerski P · 1992
Researchers exposed human lymphocytes in vitro for 5 days to continuous-wave (CW) or pulsed-wave (PW) 2450-MHz radiation at non-heating and heating levels, with actual average SARs ranging to 12.3 W/kg. At non-heating levels, CW exposure did not affect spontaneous lymphoblastoid transformation, but PW exposure enhanced it significantly (P less than .002). At heating levels, PW exposure enhanced transformation to a greater extent than either conventional heating or CW heating, a finding significant at the .02 level.
Conover DL et al. · 1992
Researchers measured foot currents in workers who stood at their normal operating positions near industrial dielectric heaters generating fields at frequencies from 6.5 to 65 MHz. Nearly 27 percent of the heaters induced foot currents exceeding the proposed 200-mA ANSI C95.1 limit, and 20 percent exceeded 350 mA. Specific absorption rates in ankles were calculated from foot currents and approximated 5 W/kg at 100 mA, 29 W/kg at 250 mA, and 57 W/kg at 350 mA, with a maximum of approximately 176 W/kg at 617 mA.
Chou CK, Guy AW, Kunz LL, Johnson RB, Crowley JJ, Krupp JH · 1992
Two hundred male Sprague-Dawley rats were assigned in equal numbers to radiation-exposure and sham-exposure conditions, with exposure beginning at 8 weeks of age and continuing daily for 25 months. The experimental rats were exposed to 2,450-MHz pulsed microwaves at 800 pps with a 10-microseconds pulse width, square-wave modulated at 8-Hz. Blood samples were analyzed at regular intervals for serum chemistries, hematological values, protein electrophoretic patterns, thyroxine, and plasma corticosterone levels.
Belyaev IYa, Alipov YD, Shcheglov VS, Lystsov VN · 1992
Researchers studied the effect of low-intensity microwaves on the conformational state of the genome of X-irradiated E. coli cells using the method of viscosity anomalous time dependencies. The frequency dependence of the observed effect had a resonance nature within the ranges of 51.62-51.84 GHz and 41.25-41.50 GHz, with a resonance half-width of the order of 100 MHz. A power density of 1 microW/cm2 was sufficient to suppress radiation-induced repair of the genome conformational state, across a tested range of 0.1-200 microW/cm2.
Adair ER, Adams BW, Hartman SK · 1992
Researchers exposed adult male squirrel monkeys to 450-MHz or 2,450-MHz continuous-wave fields in cool environments to study how the body responds to radio-frequency heating. During brief exposures in the cold, the reduction of metabolic heat production was directly proportional to the SAR, and 2,450-MHz energy was a more efficient stimulus than the resonant frequency. In the steady state, exposure at the resonant frequency produced a regulated increase in deep body temperature, described as not unlike that which occurs during exercise. Researchers concluded that skin temperature changes are the primary source of the neural signal for a change in physiological interaction processes during radio-frequency exposure in the cold.
Garaj-Vrhovac V, Fucic A, Horvat D · 1992
Researchers exposed human whole-blood samples to continuous microwave radiation at a frequency of 7.7 GHz, at power densities of 0.5, 10, and 30 mW/cm2, for 10, 30, and 60 minutes. In all experimental conditions, the frequency of all types of chromosomal aberrations was significantly higher than in the control samples, and dicentric and ring chromosomes were detected in the irradiated samples. The results showed a positive correlation between micronuclei and specific chromosomal aberrations, including acentric fragments and dicentric chromosomes. The researchers indicated that microwave radiation causes changes in the genome of somatic human cells and that the applied tests are equally sensitive for the detection of the genotoxicity of microwaves.
Unknown authors · 1991
Goodman R, Shirley-Henderson A · 1991
Researchers exposed dipteran salivary gland cells and human cells to low frequency electromagnetic fields and measured a pronounced increase in transcription. The increase in mRNA levels is most likely due to an increased rate of transcription. Frequency, field strength, and time dependent windows were observed for quantitative changes in specific transcripts. Genes not normally expressed were unaffected by the exposure. Changes in overall protein synthetic patterns also occurred.
Unknown authors · 1991
Researchers exposed lambda phage DNA to short pulses of microwave irradiation and then digested it with Eco RI and Bam HI restriction enzymes. Eco RI digestion of microwaved DNA yielded three extra fragments between 24,226 and 7,421 base pairs in addition to the six expected fragments. Bam HI digestion produced no extra fragments but showed slower fragment mobility and broader bands compared to native DNA.
Unknown authors · 1991
Researchers conducted a case-control study of 232 cases and 232 controls aged birth to 10 years in Los Angeles County from 1980 to 1987. Magnetic field measurements were taken in the child's bedroom over 24 hours or longer for 164 cases and 144 controls, and spot measurements for 140 cases and 109 controls. No clear associations were seen between leukemia risk and measured magnetic or electric fields. An association was observed between the Denver Wertheimer-Leeper wiring configuration and childhood leukemia risk with an odds ratio of 2.15. Cases were more likely than controls to report use of several appliances that produce high electric and magnetic fields.
Sandblom J, Theander S · 1991
Researchers examined the effects of microwaves on single-channel kinetics of gramicidin-A channels in lipid bilayer membranes. Microwave radiation did not affect single-channel conductance or channel lifetime beyond what would be expected from thermal effects. The rate of channel formation decreased during exposure, which is opposite to the effect expected from heating alone. The authors discussed the mechanism in terms of the dimerization process of channel formation. They attempted to separate thermal and athermal effects by measuring temperature at the membrane site and relating parameters to their known temperature dependence.
Larsen AI · 1991
Researchers conducted a case-referent study using a cohort of Danish physiotherapists linked to national pregnancy registers to assess the relation between high-frequency electromagnetic radiation exposure and congenital malformations. Exposure during the first month of pregnancy was assessed through blinded telephone interviews without knowledge of case status. No statistically significant associations were found between pregnancy outcome and high-frequency electromagnetic radiation exposure (odds ratio 1.7, 95% confidence interval 0.6-4.3).
