bluuebunny/crossref_metadata_2025 huggingface dataset:
Biologic effects of microwave exposure. II. Studies on the mechanisms controlling susceptibility to microwave‐induced increases in complement receptor‐positive spleen cells
Authors: Schlagel Charles J. , Sulek Kazimierz , Ho Henry S. , Leach William M. , Ahmed Aftab , Woody James N.
Published: February 2006

In attempting to evaluate the mechanisms responsible for susceptibility to the inductive increase in splenic complement receptor‐positive (CR+) cells following exposure to 2450‐MHz microwaves, it was found that sensitivity to microwave‐induced CR+cell increases was under genetic control. In particular, evidence was accumulated suggesting that regulation was under the control of a gene or genes closely associated with but outside of the mouse major histocompatibility complex (H‐2). All responsive strains of mice tested were of the H‐2k haplotype, while mice of the H‐2a, H‐2b, H‐2d and H‐2i5 haplotypes were refractory to the microwave‐induced increases in CR+ cells. By utilizing certain H‐2k strains of mice that were genetically unable to respond to endotoxin, we were able to show that these strains of mice responded to microwaves, but not to endotoxin, by increasing CR+ cells. Microwave‐induced increases in CR+cells were not mimicked by the intraperitoneal injection of hydrocortisone. Athymic mice responded to microwave exposure, indicating that this event was not regulated by the T‐cell population. Mice less than eight weeks old were found not to be susceptible to exposure to 2450‐MHz microwaves. These studies indicate that microwaves do induce changes in the population of cells with specific cell‐surface receptors, that susceptibility to these changes is under genetic control, and that it is unlikely that endotoxin, corticosteroids, or regulatory T cells play a significant role in the mechanisms regulating these increases.
General properties of the interaction between animals and ELF electric fields
Authors: Kaune William T. , Gillis Murlin F.
Published: February 2006

An analysis is given of the interaction between extremely low‐frequency (ELF) electric fields and animals of arbitrary body shape. This analysis is based on three approximations which are valid in the ELF range: In living tissues, capacitive (displacement) currents are negligible compared to conduction currents; effects resulting from the finite velocity of propagation of electromagnetic fields are negligible; skin effect in living tissues is negligible. Major conclusions of the analysis are: (a) The electric field outside the body, the induced charge on the surface of the body, and the total current crossing any section through the body (eg, through the neck or limbs) are completely determined by the characteristics of the applied ELF electric field, the shape of the body, its location relative to ground and other conductors, and any conduction currents from the body to ground or other conductors. (b) All of the quantities in (a) can be measured using conducting animal models. (c) The magnitudes of the electric field outside the body and the induced charge density on the surface of the body are independent of frequency, in the ELF range, when the body is either insulated from or shorted to ground (and any other conductors in the system). (d) The only quantities affected by the electrical properties of the tissues comprising the body are the current density and electric field inside the body. (e) The electric field outside and inside a body will be unchanged by a scaled change in its size.
Microwave‐induced increase of water and conductivity in submaxillary salivary gland of rats
Authors: Mikolajczyk Henryk
Published: February 2006

Hypersalivation is an important mechanism for heat dissipation by animals without sweat glands. The water content and conductivity (at 20 kHz) in sub‐maxillary salivary gland (SSG) and in other tissues were investigated in adult male rats exposed to microwaves (2880 MHz, 1.5 μs pulses at 1000 Hz) or to conventional heat at 40 °C. Eighty rats in one series were exposed, one at a time, for 30 min to microwaves producing a specific absorption rate (SAR) of 4.2,6.3,6.8,8.4,10.8 or 12.6 W/kg. Fifty rats were sham‐exposed under similar environmental conditions. In the second series, ten rats were sham‐exposed, 33 rats were exposed, one at time, for 15, 30 or 60 min to microwaves at a SAR of 9.5 W/kg, and 32 rats were exposed for similar periods to conventional heat at 40 °C. In rats of the first series colonic temperatures were elevated significantly at a SAR of 4.2 W/kg, while SSG water content and conductivity increased significantly at SAR values of 6.3 W/kg and higher. In the second series of experiments increases in colonic temperature and SSG water content were greater after 15 and 30 min of microwave exposure than after exposure to heat. Also, SSG conductivity was significantly depressed by heat and significantly increased by microwaves after exposure for 15 or 30 min. The results support the hypothesis that water content and conductivity of SSG of rats can be used as a sensitive specific test of a microwave induced thermal response.
Possible humoral mechanism of 2450‐MHz microwave‐induced increase in complement receptor positive cells
Authors: Wiktor‐Jedrzejczak Wieslaw , Schlagel Charles J. , Ahmed Aftab , Leach William M. , Woody James N.
Published: February 2006

These studies indicate that the increase in the frequency of complement receptor‐positive (CR+) spleen cells observed 6 days after a 30‐min exposure to 2450‐MHz microwaves is not the result of microwave‐induced alterations of lymphocyte recirculation patterns, but is mediated by a soluble, humoral factor produced by cells within the spleen.
Dielectric properties of animal tissues in vivo at frequencies 10 MHz – 1 GHz
Authors: Stuchly Maria A. , Athey T. Whitt , Stuchly Stanislaw S. , Samaras George M. , Taylor Glen
Published: February 2006

An open‐ended coaxial line sensor in conjunction with an automatic network analyzer was used to measure in vivo the permittivity of several feline tissues (skeletal and smooth muscle, liver, kidney, spleen, and brain – gray and white matter) at frequencies between 10 MHz and 1 GHz. The estimated uncertainties of measurement were between 1.5% and 5%. The data are in general agreement with previously obtained data in vitro and in vivo. Significant differences in the properties of different types of the same tissue (eg, skeletal and smooth muscle) were observed. Many tissues were found to be non‐homogeneous in its permittivity.
Effect of homogeneous magnetic fields on responses to toxic stimulation in spirostomum ambiguum
Authors: Ripamonti A. , Ettienne E. M. , Frankel R. B.
Published: February 2006

Effects of DC magnetic fields, up to 125,000 G, on the survival of the ciliated protozoan Spirostomum ambiguum exposed to the toxic substance 2,2′‐dipyridyldisulfide are reported. The magnetic field diminishes the ability of the organism to survive the drug, and lengthens the extension phase of the contraction cycle. It is proposed that the magnetic field alters the regulation of intracellular (C2+) transients.
Inhibition of growth rate of escherichia coli induced by extremely low‐frequency weak magnetic fields
Authors: Ramon Ceon , Ayaz M. , Streeter Daniel D.
Published: February 2006

Cultures of Escherichia coli kept at 0 °C in a phosphate buffer solution were exposed to a sinusoidal weak 60‐ or 600‐Hz magnetic field of strength 2 × 10−3 Tesla. A decrease of more than 40% in bacterial count was observed after a 60‐h exposure to the magnetic field. Electron micrographs of exposed bacteria show ruptured cell walls, possibly due to the breaking away of flagella under the influence of the sinusoidally varying electromotive force.
Equalizing the electric field intensity within chick brain immersed in buffer solution at different carrier frequencies
Authors: Joines William T. , Blackman Carl F.
Published: February 2006

Presented here are the numerical relationships between incident power densities that produce the same average electric field intensity within a chick brain half immersed in buffered saline solution and exposed to a uniform electromagnetic field at carrier frequencies of 50, 147, and 450 MHz. Calculations are based on modeling the buffer solution as a spherical shell in air with an inner concentric sphere of brain tissue. The results support our earlier conclusion that calcium efflux results obtained at different carrier frequencies are in agreement when related by the electric field within the brain.
Determination of electric current distributions in animals and humans exposed to a uniform 60‐Hz high‐intensity electric field
Authors: Guy Arthur W. , Davidow Scott , Yang Gen‐Yuan , Chou Chung‐Kwang
Published: February 2006

The thermographic method for determining specific absorption rate (SAR) in animals and models of tissues or bodies exposed to electromagnetic fields was applied to the problem of quantifying the current distribution in homogeneous bodies of arbitrary shape exposed to 60‐Hz electric fields. The 60‐Hz field exposures were simulated by exposing scale models of high electrical conductivity to 57.3‐MHz VHF fields of high strength in a large 3.66 × 3.66 × 2.44‐m TE101 mode resonant cavity. After exposure periods of 2–30 s, the models were quickly disassembled so that the temperature distribution (maximum value up to 7 °C) along internal cross‐sectional planes of the model could be recorded thermographically. The SAR, W′, calculated from the temperature changes at any point in the scale model was used to determine the SAR, W, for a full‐scale model exposed to a 60‐Hz electric field of the same strength by the relation W = (60/ f2 · (σ′/σ) · W′ where f′ is the model exposure frequency, σ′ is the conductivity of the scale model at the VHF exposure frequency, and σ is the conductivity of the full‐scale subject at 60 Hz. The SAR was used to calculate either the electric field strength or the current density for the full‐scale subject. The models were used to simulate the exposure of the full‐scale subject located either in free space or in contact with a conducting ground plane. Measurements made on a number of spheroidal models with axial ratios from 1 to 10 and conductivity from 1 to 10 s/m agreed well with theoretical predictions. Maximum current densities of 200 nA/cm2 predicted in the ankles of man models and 50 nA/cm2 predicted in the legs of pig models exposed to 60‐Hz fields at 1kV/m agreed well with independent measurements on full‐scale models.
Comparative effects of pulsed and continuous‐wave 2.8‐GHz microwaves on temporally defined behavior
Authors: Thomas John R. , Schrot John , Banvard Richard A.
Published: February 2006

The effects of pulsed‐(PW) and continuous‐wave (CW) 2.8‐GHz microwaves were compared on the performance of rodents maintained by a temporally defined schedule of positive reinforcement. The schedule involved food‐pellet reinforcement of behavior according to a differential‐reinforcement‐of‐low‐rate (DRL) contingency. The rats were independently exposed to PW and to CW fields at power densities ranging from 1 to 15 mW/cm2. Alterations of normal performance were more pronounced after a 30‐minute exposure to the PW field than to the CW field. The rate of emission of appropriately timed responses declined after exposure to PW at 10 and 15 mW/cm2, whereas exposure at the same power levels to the CW field did not consistently affect the rate of responding. Change in performance associated with microwave exposure was not necessarily related to a general decline in responding: in some instances, increases in overall rates of responding were observed.
Near‐field absorption in a circular cylinder from electric and magnetic line sources
Authors: Morita N. , Andersen J. Bach
Published: February 2006

A homogeneous, lossy circular cylinder is used as a simple model of a biological object in which interior heating is produced by the absorption of electromagnetic waves. For this model, we determined the optimum frequency, polarization, orientation and shape of applicators. Analytical and numerical results are given for both electric and magnetic line sources, with three different polarizations relative to the cylinder. Coupling efficiencies and contour plots are presented for a range of parameters. One particularly interesting result is the production of maximum energy deposition at the center of a cylinder of muscle tissue when exposed in the 100‐MHz frequency range by the use of four applicators surrounding the cylinder.
Effects of weak amplitude‐modulated microwave fields on calcium efflux from awake cat cerebral cortex
Authors: Adey W. R. , Bawin S. M. , Lawrence A. F.
Published: February 2006

Calcium (45Ca2+) efflux was studied from preloaded cortex in cats immobilized under local anesthesia, and exposed to a 3.0‐mW/cm2 450‐MHz field, sinusoidally amplitude modulated at 16 Hz (modulation depth 85%). Tissue dosimetry showed a field of 33 V/m in the interhemispheric fissure (rate of energy deposition 0.29 W/kg). Field exposure lasted 60 min. By comparison with controls, efflux curves from field exposed brains were disrupted by waves of increased 45Ca2+ efflux. These waves were irregular in amplitude and duration, but many exhibited periods of 20–30 min. They continued into the postexposure period. Binomial probability analysis indicates that the field‐exposed efflux curves constitute a different population from controls at a confidence level of 0.96. In about 70% of cases, initiation of field exposure was followed by increased end‐tidal CO2 excretion for about 5 min. However, hypercapnea induced by hypoventilation did not elicit increased 45Ca2+ efflux. Thus this increase with exposure does not appear to arise as a secondary effect of raised cerebral CO2 levels. Radioactivity measurements in cortical samples after superfusion showed 45Ca2+ penetration at about 1.7 mm/hr, consistent with diffusion of the ion in free solution.
Measurement of blood‐brain barrier permeation in rats during exposure to 2450‐MHz microwaves
Authors: Ward T. R. , Elder J. A. , Long M. D. , Svendsgaard D.
Published: February 2006

Adult rats anesthesized with pentobarbital and injected intravenously with a mixture of [14C]sucrose and [3H]inulin were exposed for 30 min to an environment at an ambient temperature of 22, 30, or 40 °C, or were exposed at 22 °C to 2450‐MHz CW microwave radiation at power densities of 0, 10, 20, or 30 mW/cm2. Following exposure, the brain was perfused and sectioned into eight regions, and the radioactivity in each region was counted. The data were analyzed by two methods. First, the data for each of the eight regions and for each of the two radioactive tracers were analyzed by regression analysis for a total of 16 analyses and Bonferroni's Inequality was applied to prevent false positive results from numerous analyses. By this conservative test, no statistically significant increase in permeation was found for either tracer in any brain region of rats exposed to microwaves. Second, a profile analysis was used to test for a general change in tracer uptake across all brain regions. Using this statistical method, a significant increase in permeation was found for sucrose but not for inulin. A correction factor was then derived from the warm‐air experiments to correct for the increase in permeation of the brain associated with change in body temperature. This correction factor was applied to the data for the irradiated animals. After correcting the data for thermal effects of the microwave radiation, no significant increase in permeation was found.
Comparison of bacterial growth to high‐intensity microwave exposure and conventional heating
Authors: Hossain M. A. , Dutta S. K.
Published: February 2006

Escherichia coli pol A+ and pol A− strains were exposed to 8.8‐GHz microwaves pulsed at 1,000 Hz (1‐μs pulse width) and an SAR of 40 W/kg, which increased the temperature of the cell culture by 7 °C. Two‐way analysis of variance showed no significant difference between the growth rates of microwave irradiated and thermally exposed cells.
Electric‐field exposure of persons using video display units
Authors: Harvey S. M.
Published: February 2006

Electric fields produced by a selection of video display units have been measured over a frequency range from DC to 1 MHz. The magnitude and the time variation of the electric fields were both recorded by means of a single broadband capacitive sensor located on the surface of a simple simulation of the human body. The electric field at a given location was found to be the sum of three discrete components, each having a different spatial and time variation. These components are produced by, respectively, the charged CRT screen, the flyback transformer, and the low‐voltage circuitry. For the units tested, operator exposures are substantially below the limits of existing workplace guidelines.
The effects of hyperthermia and hyperthermia plus microwaves on rat brain energy metabolism
Authors: Sanders Aaron P. , Joines William T.
Published: February 2006

The effects of hyperthermia, alone and in conjunction with microwave exposure, on brain energetics were studied in anesthetized male Sprague‐Dawley rats. The effect of temperature on adenosine triphosphate concentration [ATP] and creatine phosphate concentration [CP] was determined in the brains of rats that were maintained at 35.6, 37.0, 39.0, and 41.0°C. At 37, 39, and 41°C brain [ATP] and [CP] were down 6.0, 10.8, and 29.2%, and 19.6, 28.7, and 44%, respectively, from the 35.6°C control concentrations. Exposure of the brain to 591‐MHz radiation at 13.8 mW/cm2 for 0.5, 1.0, 3.0, and 5.0 min caused further decreases (below those observed for 30°C hyperthermia only) of 16.0, 29.8, 22.5, and 12.3% in brain [ATP], and of 15.6, 25.1, 21.4, and 25.9% in brain [CP] after 0.5, 1.0, 3.0, and 5.0 min, respectively. Recording of brain reduced nicotinamide adenine dinucleotide (NADH) fluorescence before, during, and after microwave exposure showed an increase in NADH fluorescence during microwave exposure that returned to preexposure levels within 1 min postexposure. Continuous recording of brain temperatures during microwave exposures showed that brain temperature varied between −0.1 and +0.05°C. Since the microwave exposures did not induce tissue hyperthermia, it is concluded that direct microwave interaction at the subcellular level is responsible for the observed decrease in [ATP] and [CP].
Viability and phagocytosis of neutrophils exposed in vitro to 100‐MHz radiofrequency radiation
Authors: Cleary Stephen F. , Liu Li‐Ming , Garber Francine
Published: February 2006

Rabbit polymorphonuclear leucocytes (PMN, neutrophils) obtained from peritoneal exudate were exposed in vitro for one‐half or one hour to continuous wave or amplitudemodulated (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°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°C no effect on PMN viability would be expected but phagocytosis would be reduced by approximately 6%/°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.
Influence of constant magnetic fields on certain physiochemical properties of water
Authors: Gonet Bolesław
Published: February 2006

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.
A cytohistological analysis of roots whose growth is affected by a 60‐Hz electric field
Authors: Brulfert Annie , Miller Morton W. , Robertson Dominique , Dooley David A. , Economou Peter
Published: February 2006

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.
Operant control of convective cooling and microwave irradiation by the squirrel monkey
Authors: Bruce‐Wolfe Virginia , Adair Eleanor R.
Published: February 2006

Adult male squirrel monkeys (Saimiri sciureus) were individually chair‐restrained in an air‐conditioned Styrofoam box in the far field of a horn antenna. Each monkey first received extensive training to regulate the temperature of the air circulating through the box by selecting between 10 and 50°C air source temperatures. Then, to investigate the ability of the animals to utilize microwaves as a source of thermalizing energy, 2450‐MHz continuous wave microwaves accompanied by thermoneutral (30°C) air were substituted for the 50°C air. Irradiation at each of three power densities was made available, ie, at 20, 25, and 30 mW/cm2 [SAR = 0.15 (W/kg)/(mW/cm2)]. The percentage of time that the monkeys selected microwave irradiation paired with thermoneutral air averaged 90% at 20 and at 25 mW/cm2. The mean percentage declined reliably (p < 0.001) to 81% at 30 mW/cm2, confirming the monkey's ability to utilize microwave irradiation as a source of thermal energy during the course of behavioral thermoregulation. All animals readily made the warm‐air to microwave‐field transition, regulating rectal temperature with precision by sequentially selecting 10°C air, then microwave irradiation accompanied by 30°C air. Although the selection of cooler air resulted in a slight reduction of skin temperatures, normal rectal temperature was maintained. The results indicate that the squirrel monkey can utilize a microwave source in conjunction with convective cooling to regulate body temperature behaviorally.
Effect of 9.6‐GHz pulsed microwaves on the orb web spinning ability of the cross spider (Araneus diadematus)
Authors: Liddle C. G. , Putnam J. P. , Lewter O. L. , Lewis J. Y. , Bell B. , West M. W. , Stead A.
Published: February 2006

Eight cross spiders (Araneus diadematus) were exposed overnight (16 h) during web‐building activity to pulsed 9.6‐GHz microwaves at average power densities of 10, 1, and 0.1 mW/cm2 (estimated SARs 40, 4, and 0.4 mW/g). Under these conditions, 9.6‐GHz pulsed microwaves did not affect the web‐spinning ability of the cross spider.
Specific absorption rate in electrically coupled biological samples between metal plates
Authors: Joines William T. , Blackman Carl F. , Spiegel Ronald J.
Published: February 2006

The specific absorption rate (SAR) in a biological sample irradiated by electromagnetic fields between the metal plates of a transmission line can be altered significantly by the spacing of the metal plates and the distance between neighboring samples. The SAR in spherical biological samples is calculated for a number of neighboring sample arrangements and metal‐plate spacings by using the method of images and induced dipole coupling. For a decrease in metal‐plate spacing, the derived equations predict an increase in SAR within a sample and a decrease in SAR with a decrease in neighboring‐sample spacing. The calculations are compared with measurements made with the aid of an array of 1‐in radius metal hemispheres on the lower plate of two parallel plates (thus forming an image system). The hemisphere on which measurements are taken is insulated from the metal plate and is connected via a coaxial center conductor to an HP 3582A spectrum analyzer that measures the voltage and hence the electric field intensity at the hemisphere. Measurements made at a frequency where wavelength is large compared with sample size (48 Hz) are in good agreement with calculations.
Off‐center spherical model for dosimetry calculations in chick brain tissue
Authors: Gonzalez Guillermo , Nearing James C. , Spiegel Ronald J. , Joines William T.
Published: February 2006

This paper presents calculations for the electric field and absorbed power density distribution in chick brain tissue inside a test tube, using an off‐center spherical model. It is shown that the off‐center spherical model overcomes many of the limitations of the concentric spherical model, and permits a more realistic modeling of the brain tissue as it sits in the bottom of the test tube surrounded by buffer solution. The effect of the unequal amount of buffer solution above the upper and below the lower surfaces of the brain is analyzed. The field distribution is obtained in terms of a rapidly converging series of zonal harmonics. A method that permits the expansion of spherical harmonics about an off‐center origin in terms of spherical harmonics at the origin is developed to calculate in closed form the electric field distribution. Numerical results are presented for the absorbed power density distribution at a carrier frequency of 147 MHz. It is shown that the absorbed power density increases toward the bottom of the brain surface. Scaling relations are developed by keeping the electric field intensity in the brain tissue the same at two different frequencies. Scaling relations inside, as well as outside, the brain surface are given. The scaling relation distribution is calculated as a function of position, and compared to the scaling relations obtained in the concentric spherical model. It is shown that the off‐center spherical model yields scaling ratios in the brain tissue that lie between the extreme values predicted by the concentric and isolated spherical models.
Brain temperature measurements in rats: A comparison of microwave and ambient temperature exposures
Authors: Ward Thomas R. , Svensgaard David J. , Spiegel Ronald J. , Puckett Earl T. , Long Merritt D. , Kinn James B.
Published: February 2006

In an effort to understand microwave heating better, regional brain and core temperatures of rats exposed to microwave radiation (2450 MHz) or elevated air temperatures were measured in two studies. In general, we have found no substantial evidence for temperature differentials, or “hot spots,” in the brain of these animals. In the first study, after a 30‐min exposure, no temperature differences between brain regions either after microwave or ambient air exposure were found. However, a highly significant correlation between brain and core temperatures was found and this correlation was the same for both microwave and ambient air heating. In the second study, time‐temperature profiles were measured in rats exposed to either 30 mW/cm2 or 36.2°C. In this study, the 30‐min exposure period was divided into seven intervals and the change in temperature during each period was analyzed. Only the cortex showed significantly different heating rates between the air heating and microwave heating; however, this difference disappeared after the initial 5 min of exposure.
Effects of in vivo ultrasound hyperthermia on natural killer cell cytotoxicity in the hamster
Authors: Johnston R. L. , Rao G. Rama , Tompkins W. A. F. , Cain C. A.
Published: February 2006

The effects of in vivo ultrasound irradiation of the spleen on immunological functions were assessed with an in vitro natural killer (NK) cell cytotoxic assay. Anesthetized hamsters were exposed to 1 MHz ultrasound at intensity levels currently being used clinically for therapeutic diathermy and hyperthermia (1–5 W/cm2, for 500 sec with constant beam scanning). Hyperthermic levels in the spleen ranged from 38–43°C. Significant depression of natural killer (NK) cell activity was seen 4 h after spleen irradiation as compared to sham irradited and normal animals. A return towards normal levels was observed in experimental groups at 24 h after exposure. Sham and normal animals were not significantly different in NK activity, indicating no significant stress‐related immunosuppressive effects due to handling. Differential leukocyte counts taken for each exposure condition showed significant lymphopenia at 4, 8, and 16 h after exposure, near normal levels at 24 h, and complete recovery by 48 h. The number of circulating mononuclear cells at 4 h showed a dose‐related suppression as the exposure intensities were increased.
Metabolic and vasomotor responses of rhesus monkeys exposed to 225‐MHz radiofrequency energy
Authors: Lotz W. Gregory , Saxton Jack L.
Published: February 2006

A previous study showed a substantial increase in the colonic temperature of rhesus monkeys (Macaca mulatta) exposed to radiofrequency (RF) fields at a frequency near whole‐body resonance and specific absorption rates (SAR) of 2–3 W/kg. The present experiments were conducted to determine the metabolic anad vasomotor responses during exposures to similar RF fields. We exposed five adult male rhesus monkeys to 225 MHz radiation (E orientation) in an anechoic chamber. Oxygen consumption and carbon dioxide production were measured before, during, and after RF exposure. Colonic, tail and leg skin temperatures were continuously monitored with RF‐nonperturbing probes. The monkeys were irradiated at two carefully‐controlled ambient temperatures, either cool (20 °C) or thermoneutral (26 °C). Power densities ranged from 0 (sham) to 10.0 mW/cm2 with an average whole‐body SAR of 0.285 (W/kg)/(mW/cm2). We used two experimental protocols, each of which began with a 120‐min pre‐exposure equilibration period. One protocol involved repetitive 10‐min RF exposures at successively higher power densities with a recovery period between exposures. In the second protocol, a 120‐min RF exposure permitted the measurement of steady‐state thermoregulatory responses. Metabolic and vasomotor adjustments in the rhesus monkey exposed to 225 MHz occurred during brief or sustained exposures at SARs at or above 1.4 W/kg. The SAR required to produce a given response varied with ambient temperature. Metabolic and vasomotor responses were coordinated effectively to produce a stable deep body temperature. The results show that the thermoregulatory response of the rhesus monkey to an RF exposure at a resonant frequency limits storage of heat in the body. However, substantial increases in colonic temperature were not prevented by such responses, even in a cool environment.
Behavioral effects of chronic exposure to 0.5 mW/cm2 of 2,450‐MHz microwaves
Authors: Dewitt John R. , D'Andrea John A. , Emmerson Rita Y. , Gandhi Om P.
Published: February 2006

Adult male, Long‐Evans rats were exposed 7 h a day for 90 days to continuous wave (CW) 2,450‐MHz microwaves at an average power density of 0.5 mW/cm2. Exposures were in a monopole‐above‐ground radiation chamber with rats in Plexiglas cages. The resulting specific absorption rate (SAR) was 0.14 W/kg (±0.01 SEM). Additional rats served as sham‐exposed and home‐caged controls. All were evaluated daily for body mass and food and water intakes. Once each 30 days, throughout baseline and exposure phases of the experiment, rats in the sham‐ and microwave‐exposed groups were tested for their sensitivity to footshock. After 90‐days of exposure, the rats were evaluated an open field, an active avoidance task and an operant task for food reinforcement. Performance of sham‐and microwave‐irradiated rats was reliably different on only one measure, the lever‐pressing task. The general conclusion reached was that exposure to CW 2,450‐MHz microwave radiation at 0.5 mW/cm2 was below the threshold for behavioral effects over a wide range of variables, but did have an effect on a time‐related operant task, although the direction of the effect was unpredictable.
Some behavioral effects of short‐term exposure of rats to 2.45 GHz microwave radiation
Authors: Mitchell Clifford L. , McRee Donald I. , Peterson N. John , Tilson Hugh A.
Published: February 2006

Rats were tested for neurobehavioral alterations immediately after exposure to 2.45‐GHz (CW) microwave radiation at 10 mW/cm2 for 7 h. Behavioral tests used were locomotor activity, startle to an acoustic stimulus and acquisition and retention of a shock‐motivated passive avoidance task. Both horizontal and vertical components of locomotor activity were assessed in 5‐min epochs for a period of 30 min using photoelectric detectors. Microwave‐exposed animals exhibited less activity than sham‐exposed animals. This was most evident during the last 10–15 min of the 30‐min test session. Twenty identical acoustical stimuli (8 KHz, 110 dB) were delivered to each rat at 40‐s intervals. The microwave‐exposed animals were less responsive to the stimuli than sham‐exposed animals. Microwave exposure had no effect on the retention of a passive avoidance procedure when tested at 1 week after training. Both the locomotor activity and acoustic startle data demonstrate that, under the conditions of this experiment, microwave exposure may alter responsiveness of rats to novel environmental conditions or stimuli.
Electromagnetic pulse propagation in dispersive planar dielectrics
Authors: Moten Krishnan , Durney Carl H. , Stockham Thomas G.
Published: February 2006

The responses of a plane‐wave pulse train irradiating a lossy dispersive dielectric half‐space are investigated. The incident pulse train is expressed as a Fourier series with summing done by the inverse fast Fourier transform. The Fourier series technique is adopted to avoid the many difficulties often encountered in finding the inverse Fourier transform when transform analyses are used. Calculations are made for propagation in pure water, and typical waveforms inside the dielectric half‐space are presented. Higher harmonics are strongly attenuated, resulting in a single continuous sinusoidal waveform at the frequency of the fundamental depth in the material. The time‐averaged specific absorption rate (SAR) for pulse‐train propagation is shown to be the sum of the time‐averaged SARs of the individual harmonic components of the pulse train. For the same average power, calculated SARs reveal that pulse trains generally penetrate deeper than carrier‐frequency continuous waves but not deeper than continuous waves at frequencies approaching the fundamental of the pulse train. The effects of rise time on the propagating pulse train in the dielectrics are shown and explained. Since most practical pulsed systems are very limited in bandwidth, no pronounced differences between their response and continuous wave (CW) response would be expected. Typical results for pulse‐train propagation in arrays of dispersive planar dielectric slabs are presented. Expressing the pulse train as a Fourier series provides a practical way of interpreting the dispersion characteristics from the spectral point of view.
Specific absorption rate (SAR) in models of the human head exposed to hand‐held UHF portable radios
Authors: Cleveland Robert F. , Athey T. Whit
Published: February 2006

Specific absorption rate (SAR) was measured in models of the human head exposed to hand‐held portable radios (“transceivers”) transmitting at frequencies in the 800‐MHz band. An isotropic implantable electric‐field probe was used to measure internal fields induced in the head models, and SARs were determined by calculation. As well as determining representative values and distributions for SARs under various conditions, it was shown that antenna type and orientation with respect to the head are important factors affecting energy absorption.
Chronic exposure of primates to 60‐Hz electric and magnetic fields: II. Neurochemical effects
Authors: Seegal Richard F. , Wolpaw Jonathan R. , Dowman Robert
Published: February 2006

We exposed Macaca nemestrina (pig‐tailed macaques) to electric (E) and magnetic (B) fields ranging in intensity from 3 kV/m and 0.1 G to 30 kV/m and 0.9 G for three 21‐day (d) periods. Experimental animals were exposed to sham E and B fields for two 21‐d periods, one prior to and one following actual exposure to E and B fields, resulting in a total of five 21‐d periods. Control animals were exposed to sham E and B fields for the entire 105‐d interval. At the end of each 21‐d period cerebrospinal fluid (CSF) was obtained by lumbar puncture and analyzed for concentrations of homovanillic acid (HVA) and 5‐hydroxyindoleacetic acid (5‐HIAA), metabolites of dopamine and serotonin neurotransmitters, respectively, by high‐performance liquid chromatography with electrochemical detection (HPLC‐ECD). Results are based on an examination of six experimental and four control animals.

Exposure to E and B fields at all strengths was associated with a significant decline in CSF concentrations of both HVA and 5‐HIAA when statistical comparisons were made against values obtained at the end of the preexposure interval. However, HVA returned to preexposure levels during the postexposure period, while 5‐HIAA did not. No significant change in the concentrations of HVA or 5‐HIAA was noted in the control animals.

These results strongly suggest that exposure of the nonhuman primate to E and B fields can significantly affect specific biochemical estimates of nervous system function. These effects may involve alterations either in neuronal activity or in the activity of enzymes that catabolize the neurotransmitters.
Sensitive model with which to detect athermal effects of non‐ionizing electromagnetic radiation
Authors: Saffer Jeffrey D. , Profenno Louis A.
Published: February 2006

To clarify the potential of non‐ionizing electromagnetic radiation to cause biological effects by athermal mechanisms, and to initiate elucidation of those mechanisms, a model system amenable to scrutiny at the molecular level has been designed and characterized. Assessment of β‐galactosidase activity in E. coli JM101 containing the plasmid pUC8 provides a sensitive assay with many important advantages. The ability to examine at the molecular level each of the processes involved in producing β‐galactosidase should permit elucidation of the molecular mechanism(s) that give rises to an observed effect.
Studies on the alignment of fibroblasts in uniform applied electrical fields
Authors: Ross Stephen M. , Ferrier Jack M. , Aubin Jane E.
Published: February 2006

Uniform electrical fields have been applied to human gingival fibroblasts by means of uniform ionic currents passed through a thin chamber. Cells were observed to align in fields between 0.1 and 1.5 V/mm but did not display directed motion toward the anode or the cathode of the chamber. Statistical analysis of directional data was used to distinguish threshold levels of orientation at low field intensities, to quantify the dependence of alignment on time and field intensity, and to analyze differences between alignment of cells treated with the Ca2+ transport modifiers A23187, verapamil, and lanthanum. Alignment occurred at a steady rate and was dependent in a saturating fashion on field strength. The Ca2+ ionophore A23187 had a significant inhibitory effect on cell alignment in applied electrical fields; however, the Ca2+ channel blockers lanthanum and verapamil did not have a significant effect on alignment.
Effect of negative air ions on morphine‐induced changes in the latency of the tail‐flick reflex
Authors: Beardwood C. J. , Jordi P. M.
Published: February 2006

Adult male Long‐Evans rats were exposed to negatively charged air ions at high concentrations (7 × 105/cm3) for six days. Sham‐exposed rats were treated identically except that the source of ions was not activated. At the end of the exposure, the latency of the tail‐flick reflex was measured in each rat before and 30 and 60 min after an injection of morphine sulphate. The tail‐flick reflex was initiated by thermal stimulation. Two heat settings were employed, the lower considered to impart a submaximal and the higher a maximal thermal stimulus. Three morphine doses were tested: 0.5, 1.0, and 1.5 mg/kg. Statistically significant differences between ion‐exposed and sham‐exposed rats were observed in tail‐flick latencies 30 min after the administration of the two lower doses, but not after the highest dose of morphine sulphate. These differences were found at both intensities of thermal stimulation. Tail‐flick latencies measured in each group prior to morphine injection were not affected by negative‐ion exposure. The data indicate that exposure of rats to negative air ions tends to inhibit the action of morphine on the latency of the tail‐flick reflex at morphine doses below 1.0 mg/kg.
Brown‐colored deposits on hair of female rats chronically exposed to 60‐Hz electric fields
Authors: Leung F. C. , Rommereim D. N. , Miller R. A. , Anderson L. E.
Published: February 2006

An increased incidence and severity of a brownish coloration of hair has been observed around the nose and on the ears of female rats that were chronically exposed to 60‐Hz electric fields. Microscopic examination of the colored areas revealed a red‐brown globular deposit on hair shafts in affected areas without signs of physical injury.
Comparison of indices of ambient exposure to 60‐hertz electric and magnetic fields
Authors: Armstrong Ben G. , Deadman Jan Erik , Thériault Gilles
Published: February 2006

Occupational, environmental, or domestic exposure of human beings to extremely low‐frequency (50‐ or 60‐Hz) electric and magnetic fields varies continuously over time. In epidemiological studies of possible health effects, exposures over long durations must be aggregated in terms of simple summary indices. However, there are many different, biologically plausible, ways of aggregating the data. While awake, each of 20 electric utility personnel and 16 office workers had provided minute‐by‐minute measures of incident electric (V/m) and magnetic (μ T) fields over a 7‐day period via personal dosimeters. Once the measures were aggregated as means, medians, peaks, and other indices, intercorrelations between all index pairs were calculated; correlation matrices are presented for the utility and office workers both by group and when pooled. Product‐moment coefficients (r) greater that .80 were found between the time‐weighted arithmetic mean (TWA) and indices that explicitly emphasize short but highly intense exposures, such as peak values and time above thresholds. Medians and geometric means were less highly correlated with the TWA. Use of only a few indices, perhaps the TWA alone, may sacrifice but little statistical power in most epidemiological studies of utility workers exposed to ELF fields. However, correlations between electric‐field strength and magnetic‐field density were generally quite weak, as were correlations of either with high‐frequency transients; these findings underscore the need to measure each of these variables in epidemiological studies. Indices of exposure incurred outside the workplace were less strongly correlated, which may indicate the need to use several indices in general‐population studies.
Search for ion‐cyclotron resonance in an Na+‐transport system
Authors: Liboff Abraham R. , Parkinson W. C.
Published: February 2006

Colonic tissue from the turtle (Pseudemys scripta) was exposed in a Ussing chamber to simultaneously applied static and time‐varying magnetic fields. Transepithelial differences of potential were monitored as frequency of the AC field was varied continuously or in discrete steps from 3 to 770 Hz. Density of the DC field was varied from 10 to 220 μT and that of the AC field from 1 to 20 μT. Short‐circuit currents through tissue were monitored for changes that might have been observed under ion‐cyclotron resonance (ICR) conditions for each of several ions: H+, Li+, Na+, K+, Ca2+, and Cl−. No discernible changes of transepithelial current were observed. The negative findings are discussed in relation to positive and negative findings that have appeared in the literature.
Electromagnetic pulsed‐wave radiation in spherical models of dispersive biological substances
Authors: Moten Krishnan , Durney Carl H. , Stockham Thomas G.
Published: February 2006

In analytical studies, we investigated induced‐field patterns and SAR distributions in a lossy, dispersive, homogeneous, dielectric sphere typical of muscle tissue as irradiated by a plane‐wave pulse train consisting of a pulse‐modulated sinusoidal carrier wave. Calculations were made for carrier frequencies of 1, 3, and 15 GHz, pulse widths of 0.333, 2.0 and 4 ns, and pulse repetition rates of 1.11 × 106, 100 × 106, and 181.18 × 106pps. The classical Mie solution was modified for a train of incident pulses that was represented by a Fourier series, and the fast‐Fourier transform was used to sum the series. Computationally, the technique proved to be feasible and less expensive than we expected. The calculated field patterns show that the sphere's physical dimensions and the internal wavelength of the carrier greatly influence the nature of pulse‐train propagation in the sphere. Harmonics having internal wavelengths nearly equal to the radius of the sphere produce most of the absorption; other harmonics produce little absorption. An intense hot spot is observed in spheres with radii that match the carriers' wavelengths.
Magnetic field exposure assessment for adult residents of maine who live near and far away from overhead transmission lines
Authors: Kavet Robert , Silva J. Michael , Thornton David
Published: February 2006

Sixty‐Hz magnetic field exposures were measured for 45 adult residents of Maine. Thirty of the subjects resided near rights‐of‐way (ROWs) with either 345‐ and 115‐kV transmission lines, or ROWs with only 115‐kV transmission lines; fifteen resided far from any transmission lines. Personal exposure data for a single 24‐hour period was acquired with the EMDEX. The EMDEX's event‐marker button was used to partition exposures into Home and Away components. Also, three area measurements were taken for each subject during the personal exposure measurement period: 1) 24‐hr fixed‐site bedroom measurement with a second EMDEX; 2) Spot measurements in at least three rooms of every residence; and 3) Spot measurements outside each residence. Residence near transmission lines highly loaded during the measurement period was associated with increased Home and Total exposure relative to a far‐away population. Average exposure level while away from home was uniform (at about 2 mG) throughout the study population. On a quantitative level, Home exposure was correlated equivalently with Spot‐In (r = .70) and the 24‐hr fixed site measurement (r = .68). Correlations of area measurements with Total exposure were weaker because of the dilution effect of Away exposure (r = .64 for Spot‐In; r = .61 for 24‐h Bedroom). Away and Home exposures were not correlated (r = .14), which reinforced our confidence that the participants used the EMDEX correctly. The data suggest the need for caution before inferences are drawn about total personal exposure from area measurements. The study demonstrates the feasibility of obtaining valid measures of magnetic‐field exposure with the personal exposure monitors that have been developed.
Bursting responses of Lymnea neurons to microwave radiation
Authors: Bolshakov M. A. , Alekseev S. I.
Published: February 2006

Microelectrode and voltage‐clamp techniques were modified to record spontaneous electrical activity and ionic currents of Lymnea stagnalis neurons during exposure to a 900‐MHz field in a waveguide‐based apparatus. The field was pulse‐modulated at repetition rates ranging from 0.5 to 110 pps, or it was applied as a continuous wave (CW). When subjected to pulsed waves (PW), rapid, burst‐like changes in the firing rate of neurons occurred at SARs of a few W/kg. If the burst‐like irregularity was present in the firing rate under control conditions, irradiation enhanced its probability of occurrence. The effect was dependent on modulation, but not on modulation frequency, and it had a threshold SAR near 0.5 W/kg. CW radiation had no effect on the firing rate pattern at the same SAR. Mediator‐induced, current activation of acetyl‐choline, dopamine, serotonin, or gamma‐aminobutyric‐acid receptors of the neuronal soma was not altered during CW or PW exposures and, hence, could not have been responsible for the bursting effect. © 1992 Wiley‐Liss, Inc.