Showing papers in "Bioelectromagnetics in 1985"
TL;DR: The results appear to describe a resonance-like relationship in which the frequency of the electromagnetic field that can induce a change in efflux is proportional to a product of LGF density and an index, 2n + 1, where n = 0,1.
Abstract: Two independent laboratories have demonstrated that electromagnetic radiation at specific frequencies can cause a change in the efflux of calcium ions from brain tissue in vitro. In a local geomagnetic field (LGF) at a density of 38 microTesla (microT), 15- and 45-Hz electromagnetic signals (40 Vp-p/m in air) have been shown to induce a change in the efflux of calcium ions from the exposed tissues, whereas 1- and 30-Hz signals do not. We now show that the effective 15-Hz signal can be rendered ineffective when the LGF is reduced to 19 microT with Helmholtz coils. In addition, the ineffective 30-Hz signal becomes effective when the LGF is changed to +/- 25.3 microT or to +/- 76 microT. These results demonstrate that the net intensity of the LGF is an important variable. The results appear to describe a resonance-like relationship in which the frequency of the electromagnetic field that can induce a change in efflux is proportional to a product of LGF density and an index, 2n + 1, where n = 0,1. These phenomenological findings may provide a basis for evaluating the apparent lack of reproducibility of biological effects caused by low-intensity extremely-low-frequency (ELF) electromagnetic signals. In future investigations of this phenomenon, the LGF vector should be explicitly described. If the underlying mechanism involves a general property of tissue, then research conducted in the ambient electromagnetic environment (50/60 Hz) may be subjected to unnoticed and uncontrolled influences, depending on the density of the LGF.
361 citations
TL;DR: A 45-Hz field causes enhanced efflux in an intensity range around 40 Vp-p/m that is essentially identical to the response observed for 16-Hz fields, and exposures over a series of frequencies reveal two frequency regions that elicitEnhanced efflux.
Abstract: We have previously shown that 16-Hz, sinusoidal electromagnetic fields can cause enhanced efflux of calcium ions from chick brain tissue, in vitro, in two intensity regions centered on 6 and 40 Vp-p/m. Alternatively, 1-Hz and 30-Hz fields at 40 Vp-p/m did not cause enhanced efflux. We now demonstrate that although there is no enhanced efflux associated with a 42-Hz field at 30, 40, 50, or 60 Vp-p/m, a 45-Hz field causes enhanced efflux in an intensity range around 40 Vp-p/m that is essentially identical to the response observed for 16-Hz fields. Fields at 50 Hz induce enhanced efflux in a narrower intensity region between 45 and 50 Vp-p/m, while radiofrequency carrier waves, amplitude modulated at 50 Hz, also display enhanced efflux over a narrow power density range. Electromagnetic fields at 60 Hz cause enhanced efflux only at 35 and 40 Vp-p/m, intensities slightly lower than those that are effective at 50 Hz. Finally, exposures over a series of frequencies at 42.5 Vp-p/m reveal two frequency regions that elicit enhanced efflux--one centered on 15 Hz, the other extending from 45 to 105 Hz.
232 citations
TL;DR: Helix aspersa neurons were irradiated with continuous-wave and noise-amplitude-modulated microwaves in a specially designed waveguide exposure system and showed that exposure of snail neurons to CW microwaves inhibited spontaneous activity and reduced input resistance at 8 degrees and 21 degrees C but not at 28 degrees C.
Abstract: Helix aspersa neurons were irradiated with continuous-wave (CW) and noise-amplitude-modulated microwaves (carrier frequency 2450 MHz, 20% AM, 2 Hz-20 kHz) in a specially designed waveguide exposure system. Continuous-wave microwave irradiations were conducted at 8 degrees, 21 degrees, and 28 degrees C, while noise-modulated irradiation was performed at 21 degrees C. The results showed that exposure of snail neurons to CW microwaves for 60 min at 12.9 W/kg inhibited spontaneous activity and reduced input resistance at 8 degrees and 21 degrees C but not at 28 degrees C. The relative decrease in resistance at 21 degrees C was half that at 8 degrees C. Exposure of neurons to noise-modulated microwaves at 6.8 and 14.4 W/kg predominately caused excitatory responses characterized by augmented membrane resistance and the appearance of greater activity. The effect differed qualitatively from the inhibition observed with continuous, unmodulated microwave irradiation.
70 citations
TL;DR: Current-density data given in this paper can be directly extrapolated to higher frequencies, at least to 1 MHz, and may be useful to individuals and groups involved in the determination of safety standards for the lower radiofrequency region.
Abstract: This paper gives current densities measured in homogeneous grounded human models exposed to vertical, 60-Hz electric fields. The methods used for these measurements were validated by measuring the current densities induced in a grounded hemisphere and in a grounded prolate hemispheroid; agreement between measurement and theory was good. For an unperturbed field strength of 10 kV/m, current densities measured in the human chest were in the range 125-300 nA/cmS. A strong horizontal current-density enhancement was observed in the axillae, with peak values of about 400 nA/cmS. The vertical current density in the arms, when held downward, was in the opposite direction to that in the chest. Current densities in the abdomen, pelvis, and legs were a strong function of whether the body was grounded through one or both feet. With one foot grounded, the horizontal current density in the lower pelvic region, just above the crotch, was 770 nA/cmS. This value was the largest of those measured in the head, arms, or torso of the human model. Scaling factors derived from these data and similar data for animals will provide a quantitative basis for comparing animal and human exposure to 60-Hz electric fields. In addition, current-density data given in thismore » paper can be directly extrapolated to higher frequencies, at least to 1 MHz. 29 references, 8 figures, 3 tables.« less
69 citations
TL;DR: Both eyes of anesthetized cynomolgus monkeys (Macaca fascicularis) were irradiated with 2.45-GHz microwaves, either pulsed or continuous wave, to observe and confirm in vivo corneal endothelial abnormalities after a 16- to 48-hour postexposure period.
Abstract: Both eyes of anesthetized cynomolgus monkeys (Macaca fascicularis) were irradiated with 2.45-GHz microwaves, either pulsed or continuous wave. In vivo corneal endothelial abnormalities were observed by specular microscopy and confirmed through histologic techniques after a 16- to 48-hour postexposure period. Pulsed microwaves with an average power density of 10 mW/cm2 (equivalent to a specific absorption rate (SAR) = 2.6 W/kg) produced these effects, while levels of 20-30 mW/cm2 (equivalent to a SAR = 5.3 to 7.8 W/kg) with continuous wave irradiation were required to produce similar changes.
65 citations
TL;DR: Dosimetry studies for seven different exposure conditions to determine whether these different results could be due to the rats having been exposed differently and local SARs in the brain varied for different Exposure conditions are presented.
Abstract: Both positive and negative biological effects of microwaves on drug actions in rats exposed to 1-mW/cm2, 2,450-MHz microwaves have been reported by several investigators We conducted dosimetry studies for seven different exposure conditions to determine whether these different results could be due to the rats having been exposed differently They included anterior and posterior exposures in a circular waveguide, near field, far field with E- or H-field parallel to the long axis of the body and dorsal exposure in a miniature anechoic chamber with E- or H-field parallel to the long axis of the body The average specific absorption rates (SARs) in the head, tail, and body of the exposed rats were measured by means of a calorimetry system The local SARs at eight locations in the brain were determined by temperature measurement with Vitek probes Intensive coupling of energy to the tail when it was exposed parallel to the E-field was shown by thermography For the same average incident power density, the average SARs in the heads of rats were about two times higher in the circular waveguide than for other exposures The local SARs in the brain varied for different exposure conditions Statistical comparisons of SARs under the different exposure conditions are presented
61 citations
TL;DR: The microwave-induced increase in brain NADH and decrease in ATP and CP concentrations was not due to hyperthermia, which suggests a direct interaction mechanism and is consistent with the hypothesis of microwave inhibition of mitochondrial electron transport chain function of ATP production.
Abstract: A comparison of the effects of continuous-wave, sinusoidal-amplitude-modulated, and pulsed square-wave-modulated 591-MHz microwave exposures on brain energy metabolism was made in male Sprague-Dawley rats (175-225 g). Brain NADH fluorescence, adenosine triphosphate (ATP) concentration, and creatine phosphate (CP) concentration were determined as a function of modulation frequency. Brain temperatures of animals were maintained between -0.1 and -0.4 degrees C from the preexposure temperature when subjected to as much as 20 mW/cm2 (average power) CW, pulsed, or sinusoidal-amplitude modulated 591-MHz radiation for 5 min. Sinusoidal-amplitude-modulated exposures at 16-24 Hz showed a trend toward preferential modulation frequency response in inducing an increase in brain NADH fluorescence. The pulse-modulated and sinusoidal-amplitude-modulated (16 Hz) microwaves were not significantly different from CW exposures in inducing increased brain NADH fluorescence and decreased ATP and CP concentrations. When the pulse-modulation frequency was decreased from 500 to 250 pulses per second the average incident power density threshold for inducing an increase in brain NADH fluorescence increased by a factor of 4--ie, from about 0.45 to about 1.85 mW/cm2. Since brain temperature did not increase, the microwave-induced increase in brain NADH and decrease in ATP and CP concentrations was not due to hyperthermia. This suggests a direct interaction mechanism and is consistent with the hypothesis of microwave inhibition of mitochondrial electron transport chain function of ATP production.
50 citations
TL;DR: The whole-body averaged SAR for the radiation frequencies examined follows a nonmonotonic function with 700 MHz as the resonant frequency, which agrees with previous analytical estimates.
Abstract: Experiments were conducted using twin-well calorimetry to determine the averaged whole-body specific absorption rate (SAR) for rat carcasses exposed to 360, 700, 915, and 2,450 MHz CW radiation in an anechoic chamber. All exposures were done with the long axis of the rat in an E-polarization. Additional experiments were conducted using a fiber optical temperature probe to determine local SAR in the brain, esophagus, colon, rectum, and tail during microwave exposure. The whole-body averaged SAR for the radiation frequencies examined follows a nonmonotonic function with 700 MHz as the resonant frequency. This result agrees with previous analytical estimates. Local SARs within the body and tail are nonuniform with significant frequency-specific hotspots in the colon, rectum, and tail.
44 citations
TL;DR: In this article, the dielectric properties of developing rabbit brain were measured at 37 degrees C between 10 MHz and 18 GHz using time domain and frequency domain systems, and it was concluded that the principal contribution to this subsidiary dispersion region arises from water of hydration.
Abstract: The dielectric properties of developing rabbit brain were measured at 37 degrees C between 10 MHz and 18 GHz using time domain and frequency domain systems. The results show a variation with age of the dielectric properties of brain. An analysis of the data suggests that the water dispersion in the brain of newly born animals can be represented by a Debye equation. This dispersion increases in complexity with age, and there is evidence of a smaller additional relaxation process centered around 1 GHz. It is concluded that the principal contribution to this subsidiary dispersion region arises from water of hydration.
36 citations
TL;DR: The eukaryotic protozoan, Paramecium, was examined as a model for effects of pulsated electromagnetic fields (PEMF) on cells and two calcium transport mutants of these organisms showed differential responses to the same field.
Abstract: The eukaryotic protozoan, Paramecium, was examined as a model for effects of pulsated electromagnetic fields (PEMF) on cells. A 72-Hz PEMF similar to fields employed clinically increased cell division rates in Paramecium by 8.5%. Two calcium transport mutants of these organisms showed differential responses to the same field. Verapamil, a calcium channel blocker, abolished any effect of PEMFs on cell division rates. A fluorescent probe that is thought to sense changes in membrane potential also manifested an altered response in the PEMF-exposed cells whereas a fluorescent lipid bilayer fluidity probe produced evidence of decreased membrane fluidity in the exposed cells. An effect of PEMFs on ion transport mediated by either a direct or indirect effect on the cell membrane is suggested by these studies.
32 citations
TL;DR: Rats were exposed to 2,450-MHz pulsed microwave fields in a circularly polarized waveguide and the same response was evoked when the incident energy density or absorbed energy density per pulse was the same, regardless of the pulse widths.
Abstract: Rats were exposed to 2,450-MHz pulsed microwave fields in a circularly polarized waveguide. The threshold incident energy density per pulse was about 1.5 to 3 microJ/cm2 over the range 1-10 microseconds. The corresponding whole-body averaged specific absorption of energy was 0.9 to 1.8 mJ/kg per pulse. The same response was evoked when the incident energy density or absorbed energy density per pulse was the same, regardless of the pulse widths.
TL;DR: RF radiation at these frequencies appears to affect red cells in a manner that is qualitatively and quantitatively different from microwave radiation.
Abstract: A field-strength-dependent hemolytic effect of continuous-wave radiofrequency (RF) exposure in vitro has been demonstrated. Erythrocytes in whole heparinized rabbit blood were hemolyzed by a 2-h exposure to 50- or 100-MHz RF fields at field strengths of greater than 4 V/cm. An effect of comparable magnitude resulted from exposure to 10-MHz RF at a field strength of 9 V/cm. Sample temperatures were maintained at 22.5 degrees +/- 0.2 degrees C. There was no apparent involvement of heating or temperature gradients, nor were there any RF exposure effects on cellular K+ or Na+ concentration, nor on pH. The mechanism of the hemolytic effect is not known. Since the percentage of lysed erythrocytes was less than 1% and there was an absence of effects on cellular cation concentrations, RF radiation may have irreversibly altered the plasma membrane permeability of a sensitive subpopulation of red cells (possibly aged cells) leading to osmotic lysis. RF radiation at these frequencies appears to affect red cells in a manner that is qualitatively and quantitatively different from microwave radiation.
TL;DR: The dielectric constant, pH, and surface tension of water exposed to CMF action were studied and the results fail to confirm the changes observed by some authors.
Abstract: There has been considerable recent interest in the question of effects of constant magnetic fields (CMF) on living organisms. The possible alteration of the physiochemical properties of water appears to be one example of such an influence. The dielectric constant, pH, and surface tension of water exposed to CMF action were studied. The results fail to confirm the changes observed by some authors. Controversial opinions on this problem are also summarized and discussed.
TL;DR: Female rats were trained to detect a vertical, 60-Hz electric field using the same apparatus and procedure used previously to study behavioral detection of the field by male rats.
Abstract: Female rats were trained to detect a vertical, 60-Hz electric field using the same apparatus and procedure the authors used previously to study behavioral detection of the field by male rats. Each rat was trained individually to press a lever in the presence of the field and not to press in its absence. Correct detections occasionally produced a food pellet. The probability of detecting the field increased as field strength increased. The threshold of detection - i.e., the field strength required for detections at a probability of 0.5 after correction for errors - varied among rats between 3 and 10 kV/m. Behavioral detection by female rats was indistinguishable from that by male rats. 17 references, 1 figure.
TL;DR: The spatial distribution of the specific absorption rate was measured in a full-scale model of man using implantable electric field probes and the average SAR in the whole-body and body parts was reported.
Abstract: The spatial distribution of the specific absorption rate (SAR) was measured in a full-scale model of man using implantable electric field probes. The model was exposed in the near-field of linear and aperture antennas at 350 MHz. Effects of the wave polarization, antenna position and antenna gain on the SAR distribution and the average SAR in the whole-body and body parts are reported.
TL;DR: Results suggest that MW exposure augments the primary IgM response to SRBC by affecting some early event in the immune response process, and the various possible explanations for this phenomenon are discussed.
Abstract: Microwave exposure has been reported to affect various components of the immune system. In this study, we examined the effect of a single whole-body exposure of hamsters to microwave (mw) energy (2.45 GHz; 5-25 mW/cm2; 1 h) on the IgM antibody (Ab) response of spleen cells to sheep red blood cells (SRBC). MW-exposed, sham-exposed, and cage-control hamsters were immunized with SRBC and plaque-forming cells (PFC) in spleens assayed using the direct hemolytic plaque assay. In cage-control hamsters the Ab response was highest between days 4 and 5, returning to baseline by day 9. MW exposure (25 mW/cm2 for 1 h) significantly augmented PFC response only on days 4 and 5 postimmunization, causing approximately a 4.3- and 3.5-fold increase over controls, respectively. Exposure to 15 mW/cm2 caused a lesser, but significant increase in PFC. Exposure to intensities below 15 mW/cm2 for 1 h did not produce any increase in Ab response. Immunization with different concentrations of SRBC following 1 h of 25 mW/cm2 MW exposure revealed a stimulation in PFC at all concentrations ranging from 5 X 10(7) to 5 X 10(8) SRBC. Pretreatment of hamsters with MW radiation prior to immunization showed that the animals retained an increased sensitivity to SRBC for as long as 4 days after MW exposure. In contrast, exposure of hamsters to MW energy on different days after immunization showed an effect of the PFC response only if given between 0 and 1 day after immunization. These results suggest that MW exposure augments the primary IgM response to SRBC by affecting some early event in the immune response process. The various possible explanations for this phenomenon are discussed.
TL;DR: The results demonstrate the influence of temperature and support the applicability of this imaging system in non-invasive thermometry, especially for clinical hyperthermia.
Abstract: The relative transparency of biological materials to high-frequency electromagnetic waves has encouraged the development of new systems for imaging. This report describes experiments of microwave tomography conducted on a prototype. The object to be analyzed is submerged in water and is illuminated by a plane wave. The total electric field is analyzed by a microwave camera. The recorded data are then processed numerically in order to reconstruct the image that corresponds to the distribution of equivalent currents in a defined plane of a section. Experiments have been conducted on isolated kidneys with and without perfusion. The influence of the perfusing solution temperature has also been studied. These experiments show the potential of this system, especially through the correlation between microwave images and the biological structures. They also confirm previous results concerning spatial resolution and depth of exploration. Finally, the results demonstrate the influence of temperature and support the applicability of this imaging system in non-invasive thermometry, especially for clinical hyperthermia.
TL;DR: In none of these test systems did microwave or radiofrequency fields induce an elevated mutation frequency, however, a significantly higher concentration of cells was found in the bacterial cultures exposed to the 27-MHz magnetic field or 2.10-GHz pulsed microwave radiation.
Abstract: Salmonella typhimurium and Drosophila melanogaster were exposed to continuous wave (CW) 2.45-GHz electromagnetic radiation, pulsed 3.10-GHz electromagnetic radiation, CW 27.12-MHz magnetic fields, or CW 27.12-MHz electric fields (only Drosophila). The temperatures of the treated sample and the nonexposed control sample were kept constant. The temperature difference between exposed and control samples was less than +/- 0.3 degrees C. Ames' assays were made on bacteria that had been exposed to microwaves (SAR 60-130 W/kg) or RF fields (SAR up to 20 W/kg) when growing exponentially in nutrient broth. Survival and number of induced revertants to histidine prototrophy were determined by common plating techniques on rich and minimal agar plates. The Drosophila test consisted of a sensitive somatic system where the mutagenicity was measured by means of mutations in a gene-controlling eye pigmentation. In none of these test systems did microwave or radiofrequency fields induce an elevated mutation frequency. However, a significantly higher concentration of cells was found in the bacterial cultures exposed to the 27-MHz magnetic field or 2.45-GHz CW and 3.10-GHz pulsed microwave radiation.
TL;DR: No change in uptake of either tracer was found in any of the eight regions as compared with those of sham-exposed animals, and temperatures of rats were measured in eight of the brain regions by a thermistor probe that did not perturb the field.
Abstract: The permeability of the blood-brain barrier to high-and low-molecular-weight compounds has been measured as a function of continuous-wave (CW) and pulsed-microwave radiation. Adult rats, anesthetized with pentobarbital and injected intravenously with a mixture of [14C] sucrose and [3H] inulin, were exposed for 30 min at a specific absorption rate of 0.1 W/kg to 1.7-GHz CW and pulsed (0.5-microseconds pulse width, 1,000 pps) microwaves. After exposure, the brain was perfused and sectioned into nine regions, and the radioactivity in each region was counted. During identical exposure conditions, temperatures of rats were measured in eight of the brain regions by a thermistor probe that did not perturb the field. No change in uptake of either tracer was found in any of the eight regions as compared with those of sham-exposed animals.
TL;DR: This paper describes a numerical technique which can be used to develop a predictive numerical model, and it carries out this development for a test case, that of a homogeneous right-circular cylinder resting upright on-end on a ground plane and exposed to a vertical, uniform, 60-Hz electric field.
Abstract: Power-frequency electric fields are strongly perturbed in the vicinity of human beings and experimental animals. As a consequence, the extrapolation of biological data from laboratory animals to human-exposure situations cannot use the unperturbed exposure field strength as a common exposure parameter. Rather, comparisons between species must be based on the actual electric fields at the outer surfaces of and inside the bodies of the subjects. Experimental data have been published on surface and internal fields for a few exposure situations, but it is not feasible to characterize experimentally more than a small fraction of the diverse types of exposures which occur in the laboratory and in the field. A predictive numerical model is needed, one whose predictions have been verified in situations where experimental data are available, and one whose results can be used with confidence in new exposure situations. This paper describes a numerical technique which can be used to develop such a model, and it carries out this development for a test case, that of a homogeneous right-circular cylinder resting upright on-end on a ground plane and exposed to a vertical, uniform, 60-Hz electric field. The accuracy of the model is tested by comparing short-circuit currents and induced current densities predicted by it to measured values: Agreement is good.
TL;DR: In this article, roots of Pisum sativum were exposed for 48 h to 60Hz electric fields of 430 V/m in an aqueous inorganic growth medium, and the growth in length of the exposed roots was 44% of that for control roots.
Abstract: Roots of Pisum sativum were exposed for 48 h to 60-Hz electric fields of 430 V/m in an aqueous inorganic growth medium. The growth in length of the exposed roots was 44% of that for control roots. Root tips were analyzed for mitotic index and cell cycle duration. Mature, differentiated root sections from tissue produced after electrode energization were analyzed for cell lengths and number of files. The major reason for the observation that exposed roots are shorter than control roots is that cell elongation in the former is greatly diminished relative to controls.
TL;DR: Assessment of the neuroendocrine response of male Long-Evans rats to sustained or intermittent 60-Hz electric fields when exposed for 1 or 3 h at 100 kV/m found no significant differences between exposed and sham-exposed rats.
Abstract: This study was designed to assess the neuroendocrine response of male Long-Evans rats to sustained or intermittent 60-Hz electric fields when exposed for 1 or 3 h at 100 kV/m. No significant differences were noted in corticosterone, prolactin, or thyrotropin levels between exposed and sham-exposed rats. A statistically significant increase (P less than .01) in growth hormone was noted in rats exposed to intermittent electric fields for 3 h. Emphasis was placed on good experimental design and the need to avoid standard laboratory stressors (excessive handling, temperature extremes, transportation, noise, etc.) known to be present in many biomedical studies. The importance of avoiding reactions due to extraneous factors in experiments predicated on investigating physiological function in relation to electric field exposure is discussed.
TL;DR: When these results are applied to practical occupational exposure situations, the whole-body specific absorption rate does not exceed the AnSI limit of 0.4 W/kg for exposures permitted by the ANSI standard (C95.1-1982) at frequencies from 7 to 40 MHz.
Abstract: Further studies of human whole-body radiofrequency (RF) absorption rates were carried out using a TEM-cell exposure system. Experiments were done at one frequency near the grounded resonance frequency (approximately 40 MHz), and at several below-resonance frequencies. Absorption rates are small for the K and H orientations of the body, even when grounded. For the body trunk in an E orientation, the absorption rate of a sitting person is about half of the rate for the same person standing with arms at the sides; the latter in turn is about half the rate for the same subject standing with arms over the head. Two-body interactions cause no increase in absorption rates for grounded people. They do, however, increase the absorption rates for subjects in an E orientation in free space; the largest interaction occurs when one subject is lambda/2 behind the other (as seen by the incident wave). When these results are applied to practical occupational exposure situations, the whole-body specific absorption rate does not exceed the ANSI limit of 0.4 W/kg for exposures permitted by the ANSI standard (C95.1-1982) at frequencies from 7 to 40 MHz.
TL;DR: The results support the postulate that the site of action of the applied electric fields is the cell membrane in Vicia faba L.
Abstract: Growth, mitotic index, and growth rate recovery were determined for Vicia faba L. roots exposed to 60-Hz electric fields of 200, 290, and 360 V/m in an aqueous inorganic nutrient medium (conductivity 0.07-0.09 S/m). Root growth rate decreased in proportion to the increasing strength; the electric field threshold for a growth rate effect was about 230 V/m. The induced transmembrane potential at the threshold exposure was about 4-7 mV. The mitotic index was not affected by an electric field exposure sufficient to reduce root growth rate to about 35% of control. Root growth rate recovery from 31-96% of control occurred in 4 days after cessation of the 360 V/m exposure. The results support the postulate that the site of action of the applied electric fields is the cell membrane.
TL;DR: Results confirm that each microwave exposure induced a rapid decrease in M, and patterns of thermophysiological responses confirm the influence both of peripheral and of internal inputs to thermoregulation in squirrel monkeys exposed to microwaves in a cool environment.
Abstract: The present study was undertaken to investigate the thermal adjustments of squirrel monkeys exposed in a cold environment to relatively high energy levels of microwave fields. The animals (Saimiri sciureus) were equilibrated for 90 min to a cool environment (Ta = 20 degrees C) to elevate metabolic heat production (M). They were then exposed for brief (10-min) or long (30-min) periods to 2,450-MHz continuous-wave microwaves. Power densities (MPD) were 10, 14, 19, and 25 mW/cm2 during brief exposures and 30, 35, 40, and 45 mW/cm2 during long exposures (rate of energy absorption: SAR = 0.15 [W/kg]/[mW/cm2]). Individual exposures were separated by enough time to allow physiological variables to return to baseline levels. The results confirm that each microwave exposure induced a rapid decrease in M. In a 20 degree C environment, the power density of a 10-min exposure required to lower M to approximate the resting level was 35 mW/cm2 (SAR = 5.3 W/kg). During the long exposures, 20 min was needed to decrease M to its lowest level. Cessation of irradiation was associated with persistence of low levels of M for periods that depended on the power density of the preceding microwave exposure. Vasodilation, as indexed by changes in local skin temperature, occurred at a high rate of energy absorption (SAR = 4.5 W/kg) and was sufficient to prevent a dramatic increase in storage of thermal energy by the body; vasoconstriction was reinstated after termination of irradiation. Patterns of thermophysiological responses confirm the influence both of peripheral and of internal inputs to thermoregulation in squirrel monkeys exposed to microwaves in a cool environment.
TL;DR: Fertile eggs of the Coturnix quail were exposed twice a day for 30 min to 2.45-GHz continuous wave radiation at power densities of 25 or 50 mW cm-2 throughout the 17-day incubation period, lowering hatchability.
Abstract: Fertile eggs of the Coturnix quail were exposed twice a day for 30 min to 2.45-GHz continuous wave radiation at power densities of 25 or 50 mW cm-2 throughout the 17-day incubation period. Other eggs were exposed to 20 degrees C or 24 degrees C temperatures twice daily. Repeated exposures to 20 degrees C, 24 degrees C, or 25 mW cm-2 did not reduce hatchability. Irradiation at 50 mW cm-2 lowered hatchability, probably as a result of high egg temperatures. Hatchlings that had been irradiated by microwaves as embryos had normal growth rates and no obvious developmental abnormalities.
TL;DR: 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 corresponded to those produced by thermal action of microwaves.
Abstract: By use of fluorescence probes 1-anilinonaphthalene-8-sulfonic acid, 2-toluidinylnaphthal-ene-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.
TL;DR: The potential use of multiple-frequency-band radiometry as a means of noninvasive sensing of one-dimensional temperature profiles and distributions of received energy, associated with specific temperature-depth profiles, are presented.
Abstract: The potential use of multiple-frequency-band radiometry as a means of noninvasive sensing of one-dimensional temperature profiles is presented in this communication. The radiative energy transfer equation is solved numerically. Ideal-condition thermal noise spectra and distributions of received energy, associated with specific temperature-depth profiles, are presented. Performance characteristics are discussed.
TL;DR: The absence of an effect of RF exposure suggests that there was minimal undetected intrasample heating and that phagocytosis was not affected by 100-MHz RF radiation under the conditions of this study.
Abstract: Rabbit polymorphonuclear leucocytes (PMN, neutrophils) obtained from peritoneal exudate were exposed in vitro for one-half or one hour to continuous wave or amplitude-modulated (20-Hz) 100-MHz RF radiation in a temperature-controlled coaxial exposure chamber at field strengths from 2.5 to 4.1 V/cm (SARs of 120 to 341 W/kg). RF exposure at 37 +/- 0.2 degrees C had no detectable effect on PMN viability or phagocytosis compared to sham-exposed cells simultaneously subjected to the same time-temperature regime. Temperature control studies indicated that at 37 degrees C no effect on PMN viability would be expected but phagocytosis would be reduced by approximately 6%/degrees C temperature increase. The absence of an effect of RF exposure suggests that there was minimal undetected intrasample heating and that phagocytosis was not affected by 100-MHz RF radiation under the conditions of this study.
TL;DR: In this article, the authors identify and measure changes in thermoregulatory responses, both behavioral and physiological, that may occur when squirrel monkeys are exposed to 2450-MHz continuous wave microwaves 40 hr/week for 15 weeks.
Abstract: This study was designed to identify and measure changes in thermoregulatory responses, both behavioral and physiological, that may occur when squirrel monkeys are exposed to 2450-MHz continuous wave microwaves 40 hr/week for 15 weeks. Power densities of 1 or 5 mW/cm2 (specific absorption rate = 0.16 W/kg per mW/cm2) were presented at controlled environmental temperatures of 25, 30, or 35 degrees C. Standardized tests, conducted periodically, before, during, and after treatment, assessed changes in thermoregulatory responses. Dependent variables that were measured included body mass, certain blood properties, metabolic heat production, sweating, skin temperatures, deep body temperature, and behavioral responses by which the monkeys selected a preferred environmental temperature. Results showed no reliable alteration of metabolic rate, internal body temperature, blood indices, or thermoregulatory behavior by microwave exposure, although the ambient temperature prevailing during chronic exposure could exert an effect. An increase in sweating rate occurred in the 35 degrees C environment, but sweating was not reliably enhanced by microwave exposure. Skin temperature, reflecting vasomotor state, was reliably influenced by both ambient temperature and microwaves. The most robust consequence of microwave exposure was a reduction in body mass, which appeared to be a function of microwave power density.