bluuebunny/crossref_metadata_2025 huggingface dataset:
A dosimeter for assessment of exposures to ELF fields
Authors: Héroux Paul
Published: February 2006

There are currently no biological indicators of electromagnetic field exposure to aid investigation of the biological effects of ELF fields, but this hiatus is partly compensated for by the ease with which the external fields can be measured. The subject of this report is a small electronic instrument that can log electric‐, magnetic‐, and transient‐field intensities of individual subjects for a duration of two weeks, thus allowing exposure to be assessed in considerable detail. A preliminary survey conducted with the instrument has shown clear differences in domestic and occupational exposures of specific groups. Simple analytical models can be fitted to the field‐exposure data by adjusting a few parameters such as current, intensity, and distance. Such modeling may be increasingly useful as the data base on exposures expands.
Absence of a synergistic effect between moderate‐power radio‐frequency electromagnetic radiation and adriamycin on cell‐cycle progression and sister‐chromatid exchange
Authors: Ciaravino Victor , Meltz Martin L. , Erwin David N.
Published: February 2006

In our laboratories we are conducting investigations of potential interactions between radiofrequency electromagnetic radiation (RFR) and chemicals that are toxic by different mechanisms to mammalian cells. The RFR is being tested at frequencies in the microwave range and at different power levels. We report here on the I) ability of simultaneous RFR exposures to alter the distribution of cells in first and second mitoses from that after treatment by adriamycin alone, and 2) on the ability of simultaneous RFR exposure to alter the extent of sister chromatid exchanges (SCEs) induced by adriamycin alone. This chemical was selected because of its reported mechanism of action and because it is of interest in the treatment of cancer. In our studies, Chinese hamster ovary (CHO) cells were exposed for 2 h simultaneously to adriamycin and pulsed RFR at a frequency of 2,450 MHz and a specific absorption rate of 33.8 W/Kg. The maximal temperature (in the tissue‐culture medium) was 39.7 ± 0.2 °C. The experiments were controlled for chemical and RFR exposures, as well as for temperature. Verified statistically, the data indicate that the RFR did not affect changes in cell progression caused by adriamycin, and the RFR did not change the number of SCEs that were induced by the adriamycin, which adriamycin is known to affect cells by damaging their membranes and DNA.
Morphological and electrophysiological changes produced by electrical stimulation in cultured neuroblastoma cells
Authors: Krauthamer Victor , Bekken Marijke , Horowitz Jennifer L.
Published: February 2006

Electric fields, which were equivalent to those generated by medical devices, were applied to cultured neuroblastoma cells (mouse and human) to test for morphological damage and to establish damage thresholds. Each of two methods of applying fields permitted flow of electrical current and minimized exposure of cells to electrode‐breakdown products. One method consisted of a pair of parallel wires in a Petri dish by which current was delivered within a fixed volume of flowing tissue‐culture media. With the other method, the cells were held in a confined geometrical chamber and current was applied via agar bridges. Under a given set of stimulation parameters, damage was found to be variable from cell to cell. By changing the strength of the electric field (frequency and duration of stimulation held constant), thresholds of several V/cm were found above which cell damage could be reliably produced. Depending on the intensity of the field, damage took the form of cell lysis or damage to neurites. Intracellular recordings from the mouse neuroblastoma cells revealed a correlation between a decline in resting transmembrane potential and stimulus intensity. Human neuroblastoma cells were less susceptible to damage than were the mouse neuroblastoma cells, given the same strength of applied electric fields.
Modification of the 1979 “Denver wire code” for different wire or plumbing types
Authors: Leeper Ed , Wertheimer Nancy , Savitz David , Barnes Frank , Wachtel Howard
Published: February 2006

This article examines “wire configuration coding” as used to estimate relative residential AC magnetic field exposure in epidemiological studies–and the need to alter such coding for time or locations other than those in which the code was developed. Effects of different secondary wire practices are particularly examined.
Japanese encephalitis virus (JEV): Potentiation of lethality in mice by microwave radiation
Authors: Lange David G. , Sedmak J.
Published: February 2006

The expression of Japanese Encephalitis Virus (JEV) lethality in mice requires entry of the virus into the central nervous system. This entry is presumably through the capillary endothelial cells (CEC), because entry between CECs is inhibited by bands of circumferential tight‐junctions. A viremic stage occurs during the first 4 to 5 days after JEV administration in mice, and both microwave radiation (2.45‐GHz, continuous wave, 10‐min exposure) and hypercarbia were employed to increase CEC permeability to JEV. Exposure to microwaves at power densities of 10–50 mW/cm2 resulted in a dose‐dependent increase in JEV‐induced lethality. Mice did not become tolerant or sensitized to microwave potentiation of JEV‐induced mortality because 4 daily exposures at 10 or 50 mW/cm2 (SARS, ∼ 24–98 W/kg) did not alter the lethality pattern to subsequent microwave radiation of JEV‐exposed animals. Similarly, hypercarbia (5, 10, and 20% CO2) was observed to produce a dose‐dependent increase in JEV‐induced lethality. Both microwave radiation and hypercarbia are thought to promote pinocytosis in CNS capillary endothelial cells. This may be one mechanism by which they enhance JEV‐induced lethality in adult Swiss‐Cox mice.
Investigation of AC‐DC magnetic field effects in planar phospholipid bilayers
Authors: Durney Carl H. , Kaminski Mark , Anderson Allen A. , Bruckner‐Lea Cindy , Janata Jiri , Rappaport Catherine
Published: February 2006

Observations recently reported by others indicate that a combination of a weak dc magnetic field and extremely‐low‐frequency ac magnetic field can produce resonant effects in biological systems. We report measurements of the effects of combined dc and ac magnetic fields on the dc current through channel‐free planar phospholipid membranes. The combined dc‐ac magnetic fields did affect the dc current through planar phospholipid membranes, but not in every membrane, and not consistently at the same values of magnetic flux density and frequency. None of our measurements showed resonant response akin to the cyclotron‐like resonance reported in diatoms [Smith et al., 1987] and lymphocytes [Liboff et al., 1987].
Single vs. Repeated microwave exposure: Effects on benzodiazepine receptors in the brain of the rat
Authors: Lai H. , Carino M. A. , Horita A. , Guy A. W.
Published: February 2006

We studied the effects of single (45 min) and repeated (ten daily 45‐min sessions) microwave exposures (2450‐MHz, 1 mW/cm2, average whole‐body SAR of 0.6 W/kg. pulsed at 500 pps with pulse width of 2 μs) on the concentration and affinity of benzodiazepine receptors in the cerebral cortex, hippocampus, and cerebellum of the rat. We used a receptor‐binding assay with 3H‐flunitrazepam as ligand. Immediately after a single exposure, an increase in the concentration of receptor was observed in the cerebral cortex, but no significant effect was observed in the hippocampus or cerebellum. No significant change in binding affinity of the receptors was observed in any of the brain‐regions studied. In rats subjected to repeated exposures, no significant change in receptor concentration was found in the cerebral cortex immediately after the last exposure, which may indicate an adaptation to repeated exposures. Our data also show that handling and exposure procedures in our experiments did not significantly affect benzodiazepine receptors in the brain. Because benzodiazepine receptors in the brain are responsive to anxiety and stress, our data support the hypothesis that low‐intensity microwave irradiation can be a source of stress.
Sex‐linked recessive lethal test of Drosophila melanogaster after exposure to 50‐Hz magnetic fields
Authors: Otaka Yoshihisa , Kitamura Satoshi , Furuta Masako , Shinohara Akemi
Published: February 2006

To determine whether a 50‐Hz magnetic field will induce mutations, a sex‐linked recessive lethal test of Drosophila melanogaster was performed. Adult flies were exposed at an rms flux density of 500 μT or 5 mT to the homogeneous field of a Helmholtz coil. The ambient field to which controls were exposed was less than 1 μT. Exposures took place continuously for 13 to 14 days, which correspond to the life cycle of Drosophila at 25°C About 10,000 X‐chromosomes were tested at each flux density. Recessive lethal mutation rates of 0.13, 0.21, and 0.18 percent were observed, respectively, for control, 500‐μT, and 5‐mT conditions. By the Kastenbaum‐Bowman significance test, the recessive lethal mutation rates in the 500‐μT and 5‐mT conditions did not differ from the mutation rate of controls.
Microwave‐specific heating affects gene expression
Authors: Saffer Jeffrey D. , Profenno Louis A.
Published: February 2006

The effects of low‐level microwave radiation on gene expression in Escherichia coli have been examined in a sensitive model. We confirm the previously reported existence of an increase in β‐galactosidase expression by microwave radiation—an increase not duplicated by bulk heating. However, the effect was not frequency dependent and appeared to be due to heating effects peculiar to microwaves. These results indicate that small thermal gradients may be a source of biological effects of non‐ionizing radiation.
Modification of membrane fluidity in melanin‐containing cells by low‐level microwave radiation
Authors: Phelan Anne M. , Lange David G. , Kues Henry A. , Lutty Gerard A.
Published: February 2006

The treatment of a B16 melanoma cell line with 2.45‐GHz pulsed microwaves (10 mW/cm2, 10‐μs pulses at 100 pps, 1‐h exposure; SAR, 0.2 W/kg) resulted in changes of membrane ordering as measured by EPR (electron paramagnetic resonance) reporter techniques. The changes reflected a shift from a more fluid‐like phase to a more solid (ordered) state of the cell membrane. Exposure of artificially prepared liposomes that were reconstituted with melanin produced similar results. In contrast, neither B16 melanoma cells treated with 5‐Bromo‐2‐Deoxyuridine (3 μg/day × 7 days) to render them amelanotic, nor liposomes prepared without melanin, exhibited the microwave‐facilitated increase of ordering. Inhibition of the ordering was achieved by the use of superoxide dismutase (SOD), which strongly implicates oxygen radicals as a cause of the membrane changes. The data indicate that a significant, specific alteration of cell‐membrane ordering followed microwave exposure. This alteration was unique to melanotic membranes and was due, at least in part, to the generation of oxygen radicals. © 1992 Wiley‐Liss, Inc.
Calcium binding to metallochromic dyes and calmodulin in the presence of combined, AC‐DC magnetic fields
Authors: Bruckner‐Lea Cindy , Durney Carl H. , Janata Jiri , Rappaport Catherine , Kaminski Mark
Published: February 2006

The possibility that weak, ac and dc magnetic fields in combination may affect binding equilibria of calcium‐ions (Ca2+) was investigated with two metallochromic dyes as calcium‐binding molecules: murexide and arsenazo III. Calcium‐dye equilibria were followed by measuring solution absorbances with a fiber‐optic spectrophotometer. A Ca2+‐arsenazo solution was also used indirectly to monitor the binding of Ca2+ to calmodulin. Parallel, ac and dc magnetic fields were applied to each preparation. The ac magnetic field was held constant during each of a series of experiments at a frequency in the range between 50 and 120 Hz (sine wave) or at 50 pps (square wave) and at an rms flux density in the range between 65 and 156 μT. The dc magnetic field was then varied from 0 to 299 μT at 1.3 μT increments. The magnetic fields did not measurably affect equilibria in the binding of metallochromic dyes or calmodulin to Ca2+. © 1992 Wiley‐Liss, Inc.
ELF exposure facility for human testing
Authors: Cohen Harvey D. , Graham Charles , Cook Mary R. , Phelps James W.
Published: February 2006

A laboratory facility specifically designed for controlled human exposure to 60‐Hz electric (0 to 16 kV/m) and magnetic (0 to 32 A/m, B = 0 to 40 μT) fields has been constructed. The facility presents uniform fields under controlled temperature and humidity. Special control systems allow collection of physiological data during, as well as before and after, exposure to electric fields at strengths to 16 kV/m under verified double‐blind control. Exposure to continuous or intermittent fields is possible in the facility. The capability of obtaining physiological data during actual exposure to constant or intermittent, 60‐Hz fields, and of doing so without either the subject or the experimenter being aware of actual field conditions, is a critical factor in valid experimentation. © 1992 Wiley‐Liss, Inc.
ELF in vitro exposure systems for inducing uniform electric and magnetic fields in cell culture media
Authors: Bassen H. , Litovitz T. , Penafiel M. , Meister R.
Published: February 2006

Many in vitro experiments on the biological effects of extremely low frequency (ELF) electromagnetic fields utilize a uniform external magnetic flux density (B) to expose biological materials. A significant number of researchers do not measure or estimate the resulting electric field strength (E) or current density (J) in the sample medium. The magnitude and spatial distribution of the induced E field are highly dependent on the sample geometry and its relative orientation with respect to the magnetic field. We have studied the E fields induced in several of the most frequently used laboratory culture dishes and flasks under various exposure conditions. Measurements and calculations of the E field distributions in the aqueous sample volume in the containers were performed, and a set of simple, quantitative tables was developed. These tables allow a biological researcher to determine, in a straightforward fashion, the magnitudes and distributions of the electric fields that are induced in the aqueous sample when it is subjected to a uniform, sinusoidal magnetic field of known strength and frequency. In addition, we present a novel exposure technique based on a standard organ culture dish containing two circular, concentric annular rings. Exposure of the organ culture dish to a uniform magnetic field induces different average electric fields in the liquid medium in the inner and outer rings. Results of experiments with this system, which were reported in a separate paper, have shown the dominant role of the magnetically induced E field in producing specific biological effects on cells, in vitro. These results emphasize the need to report data about the induced E field in ELF in‐vitro studies, involving magnetic field exposures. Our data tables on E and J in standard containers provide simple means to enable determination of these parameters. © 1992 Wiley‐Liss, Inc.
Measurement of magnetically induced electric fields in conductive media near a 60 Hz current‐carrying wire
Authors: Robertson‐De Mers K. A. , Miller Douglas L.
Published: February 2006

Electric fields induced in a conductive body by the magnetic field of a current‐carrying wire were analyzed theoretically and experimentally to assess the dosimetric importance of highly nonuniform, field‐exposure conditions. Experimentation revealed that a 60‐Hz magnetic field was inversely proportional to the radius of a wire bundle carrying 100 A within a 0.5‐m2 test area. A miniaturized electric field probe was used to measure the electric fields induced in 5‐cm‐deep, saline‐filled models. In the theoretical analysis, numerical estimates of induced fields were made by a spreadsheet method. The theoretical calculations and the measured values of induced electric fields were generally in good agreement. The induced fields were in a plane perpendicular to a vertically incident magnetic field; the maximally induced fields were in areas nearest the wire bundle. The strength of the induced field increased with model size: from 96 μV/cm in a 10 × 10 cm model to 176 μV/cm in a 40 × 40 cm model. The strength of the field induced in a 20 × 20 cm model decreased with increasing model‐to‐wire spacing: from 132 μV/cm for a 1‐cm spacing (2‐mT maximum, incident field) to 50 μV/cm for a 6‐cm spacing (0.33‐mT maximum). The results indicate that increases in local values of nonuniformly incident fields produce relatively small increases in induced electric fields. This finding may be important in dosimetric consideration of circumstances, such as use of electric blankets, in which fields of low average strength are accompanied by intense local fields. © 1992 Wiley‐Liss, Inc.
Development of chicken embryos following exposure to 60‐Hz magnetic fields with differing waveforms
Authors: Martin A. H.
Published: February 2006

Previous studies in my laboratory have revealed a reproducible and statistically significant increase in the number of malformations in live chicken embryos that had been exposed during the first 48 h of incubation to a pulsed magnetic field (unipolar pulses, 100‐pps, 1‐μT peak density). In marked contrast, no adverse effect was seen following similar exposure to 60‐Hz, bipolar, unipolar, or split‐sine waves at 3‐μT peak‐to‐peak. In the four experiments comprising the present study, differences in the numbers of malformations between control and experimental groups were not statistically significant. Field‐free incubation for an additional 72 h after exposure to a bipolar sine wave for 48 h resulted in an increase in normal live embryos in both control and treated groups. © 1992 Wiley‐Liss, Inc.
Criticism of Lednev's mechanism for the influence of weak magnetic fields on biological systems
Authors: Adair Robert K.
Published: February 2006

V. V. Lednev has proposed a mechanism that he suggests would allow very weak magnetic fields, at the cyclotron resonance frequency for Ca2+ ions in the earth's field, to induce biological effects. I show that for four independent reasons no such mechanism can operate. © 1992 Wiley‐Liss, Inc.
Effects of continuous and pulsed 2450‐MHz radiation on spontaneous lymphoblastoid transformation of human lymphocytes in vitro
Authors: Czerska Ewa M. , Elson Edward C. , Davis Christopher C. , Swicord Mays L. , Czerski Przemyslaw
Published: February 2006

Normal human lymphocytes were isolated from the peripheral blood of healthy donors. One‐ml samples containing (106) cells in chromosome medium 1A were exposed for 5 days to conventional heating or to continuous wave (CW) or pulsed wave (PW) 2450‐MHz radiation at non‐heating (37°C) and various heating levels (temperature increases of 0.5, 1.0, 1.5, and 2 °C). The pulsed exposures involved 1‐μs pulses at pulse repetition frequencies from 100 to 1,000 pulses per second at the same average SAR levels as the CW exposures. Actual average SARs ranged to 12.3 W/kg. Following termination of the incubation period, spontaneous lymphoblastoid transformation was determined with an image analysis system. The results were compared among each of the experimental conditions and with sham‐exposed cultures. At non‐heating levels, CW exposure did not affect transformation. At heating levels both conventional and CW heating enhanced transformation to the same extent and correlate with the increases in incubation temperature. PW exposure enhanced transformation at non‐heating levels. This finding is significant (P < .002). At heating levels PW exposure enhanced transformation to a greater extent than did conventionalor CW heating. This finding is significant at the .02 level. We conclude that PW 2450‐MHz radiation acts differently on the process of lymphoblastoid transformation in vitro compared with CW 2450‐MHz radiation at the same average SARs. © 1992 Wiley‐Liss, Inc.
Residential exposure to 60‐Hz magnetic fields from appliances
Authors: Mader D. L. , Peralta S. B.
Published: February 2006

A model has been developed that permits assessment of residential exposure to 60‐Hz magnetic fields emitted by appliances. It is based on volume‐ and time‐averaging of magnetic‐dipole fields. The model enables the contribution of appliances in the total residential exposure to be compared with that of other sources in any residence under study. Calculations based on measurements reported in the literature on 98 appliances revealed that appliances are not a significant source of whole‐body exposure, but that they may be the dominant source of exposure of the body's extremities. © 1992 Wiley‐Liss, Inc.
Preliminary report: Modification of cardiac contraction rate by pulsed magnetic fields
Authors: Ramon Ceon , Powell Michael R.
Published: February 2006

Isolated rat hearts and excised canine cardiac tissues were subjected to pulsed magnetic fields. The fields excited in coils by tandem pairings of sinusoidal pulses were presented at various inter‐pair delays and repetition rates. The waveform of the magnetic field was a single or multiple sinusoid followed after a variable delay by another single or multiple sinusoid. Small but reliable increases in the beating rate of rat heart were observed. Similar increases occurred in contraction rates of canine tissues. Both preparations exhibited a contraction‐rate dependency on the repetition rate of the paired magnetic pulses: 4.5–6 rep/s for canine tissue, and 20–25 and 40–55 reps/s for rat heart. Flux‐density thresholds for both preparations approximated 10 mT (100 gauss) rms. © 1992 Wiley‐Liss, Inc.
Electric fields induced in rat and human models by 60‐Hz magnetic fields: Comparison of calculated and measured values
Authors: Hart Francis X.
Published: February 2006

The calculated distribution of electric fields induced in homogeneous human and rat models by a 60‐Hz magnetic field is compared with values measured in instrumented mannequins. The calculated values agree well with measured values. 1992 Wiley‐Liss, Inc.
Threshold for inhibition of Na, K‐ATPase by ELF alternating currents
Authors: Blank Martin , Soo Lily
Published: February 2006

Alternating currents can increase or decrease the ATP‐splitting activity of the membrane enzyme Na,K‐ATPase. Either change depends on the AC frequency, and the greatest effect appears to be in the ELF range at about 100 Hz. The threshold for enzyme inhibition by AC was determined, and it is estimated to be an internal electric field circa 5 μV/cm. The corresponding current‐density threshold approximates 8 nA/cm2. 1992 Wiley‐Liss, Inc.
Relative‐risk‐estimate bias and loss of power in the mantel test for trend resulting from the use of magnetic‐field point‐in‐time (“spot”) measurements in epidemiological studies based on an ordinal exposure scale
Authors: Delpizzo Vincent , Salzberg Michael R.
Published: February 2006

We assessed the merits of various point‐in‐time (“spot”) measurement protocols in case‐control studies based on an ordinal exposure scale. After classifying a number of houses on the basis of prolonged monitoring of the ambient, extremely low frequency (ELF) magnetic field, we determined the probability of misclassification for each “spot” measurement protocol. We calculated the effect of this misclassification on the relative risk estimates and on the Mantel test for trend. We found that classification based on a small group of point‐in‐time measurements allows an adequate estimate of the relative risk, although the statistical significance of the dose‐response gradient may be seriously underestimated. However, the use of automated ambient‐field monitors, which results in loss of information on spatial variability, can lead to similar consequences. Therefore, manually collected point‐in‐time measurements remain a viable option for exposure assessment. 1992 Wiley‐Liss, Inc.
Increased sensitivity of the non‐human primate eye to microwave radiation following ophthalmic drug pretreatment
Authors: Kues Henry A. , Monahan John C. , D'Anna Salvatore A. , McLeod D. Scott , Lutty Gerard A. , Koslov Samuel
Published: February 2006

Previous studies in our laboratory have established that pulsed microwaves at 2.45 GHz and 10 mW/cm2 are associated with production of corneal endothelial lesions and with disruption of the blood‐aqueous barrier in the non‐human primate eye. In the study reported here we examined ocular damage in monkeys (M. mulatta and M. fascicularis) following topical treatment with one of two ophthalmic drugs (timolol maleate and pilocarpine) that preceded exposure to pulsed microwaves. Anesthetized monkeys were sham exposed or exposed to pulsed, 2.45 GHz microwaves (10 μs, 100 pps) at average power densities of 0.2, 1, 5, 10, or 15 mW/cm2 4 h a day for 3 consecutive days (respective SARs were 0.052, 0.26, 1.3, 2.6, and 3.9 W/kg). Immediately before microwave exposure, one or both eyes were treated topically with one drop of 0.5% timolol maleate or of 2% pilocarpine. Following administration of a drug, we observed a significant reduction in the power‐density threshold (from 10 to 1 mW/cm2) for induction of corneal endothelial lesions and for increased vascular permeability of the iris. Diagnostic procedures (in vivo specular microscopy and fluorescein iris angiography) were performed following each exposure protocol. In addition, increased vascular permeability was confirmed with horseradish peroxidase tracer techniques. Although we did not measure intraocular temperatures in experimental animals, the results suggest that a mechanism other than significant heating of the eye is involved. Our data indicate that pulsed microwaves at an average SAR of 0.26 W/kg, if administered after pretreatment with ophthalmic drugs, can produce significant ocular effects in the anesthetized primate. 1992 Wiley‐Liss, Inc.
Small integrating meter for assessing long‐term exposure to magnetic fields
Authors: Kaune W. T. , Niple J. C. , Liu M. J. , Silva J. M. , Ramirez J.
Published: February 2006

A small, lightweight meter has been developed for magnetic‐field measurements, particularly those needed for exposure‐assessment purposes. This meter, known as the AMEX‐3D, continuously measures all three axes of magnetic‐flux density and electronically combines the data into a single estimate of cumulative exposure to the root‐mean‐square (rms) resultant flux density. The AMEX‐3D weighs about 120 g, measures 2.7 cm x 5.1 cm x 10.2 cm, and is battery powered. Two panel‐mounted jacks are provided for measuring battery voltage and for reading cumulative exposure data from the unit. The instrument has, within 3 dB, a flat response to magnetic flux densities at all frequencies in its 30–1,000 Hz bandwidth. A detailed analysis of error sources in the AMEX‐3D leads to an estimate of ±20% as the accuracy of the instrument over its dynamic range, which extends from 0.02 to 15 μT. The AMEX‐3D was tested in the field by asking electricutility distribution linemen to wear AMEX‐3D and EMDEX meters simultaneously while working. Agreement between the two measures of exposure was excellent. 1992 Wiley‐Liss, Inc.
Statistical review of the henhouse experiments: The effects of a pulsed magnetic field on chick embryos
Authors: Handcock Mark S. , Kolassa John E.
Published: February 2006

This paper analyzes data from a study conducted by the United States Office of Naval Research on the effects of pulsed magnetic fields on chick embryos. The experiment involved incubation of eggs under carefully controlled conditions in six different laboratories. The original analysis included inappropriate statistical methodology for analyzing the experimental results. Since the conclusions from this study rest so heavily on the results of statistical analyses, choosing the proper methodology is imperative. The major aim of this paper then is to introduce more appropriate analytic tools and illustrate their use in the present context. Qualitatively our results agree with those of the original analysis; our findings about interactions between effects, however, makes interpretation of these effects more subtle. We apply linear logistic modeling to counts of damaged embryos, using as covariates factors corresponding to exposure, laboratory, incubator, run, and measurements of background radiation. This facilitates estimation of the size of the effects. The effects of laboratory, incubator, and run are explored both as fixed and random effects. We find statistically significant exposure and laboratory effects, in accordance with the original study. However, we also find that the inter‐laboratory variation in exposure effect is at least as large as the exposure effect itself. The presence of such effects fundamentally alters the interpretation of the fitted model, as is graphically presented. 1992 Wiley‐Liss, Inc.
Early history of bioelectromagnetics
Authors: Schwan Herman P.
Published: February 2006

The early history of bioelectromagnetics is reviewed as I experienced it. The period of time chosen extends from my joining the Institute for Physical Foundations of Medicine in Frankfurt in 1937 to the early 1970s, when I retired from the chair of my department at the University of Pennsylvania. Several themes emerge from these recollections. First, clinical and biological work led almost immediately to a heated controversy about the role of athermal vs. thermal effects; this issue has never been settled to the satisfaction of most. Second, good quantitative work on electrical properties and dosimetry began early, well before World War II; its impact on future developments was significant. 1992 Wiley‐Liss, Inc.
Long‐term, low‐level microwave irradiation of rats
Authors: Chou C.‐K. , Guy A. W. , Kunz L. L. , Johnson R. B. , Crowley J. J. , Krupp J. H.
Published: February 2006

Our goal was to investigate effects of long‐term exposure to pulsed microwave radiation. The major emphasis was to expose a large sample of experimental animals throughout their lifetimes and to monitor them for effects on general health and longevity.

An exposure facility was developed that enabled 200 rats to be maintained under specific‐pathogen‐free (SPF) conditions while housed individually in circularly‐polarized waveguides. The exposure facility consisted of two rooms, each containing 50 active waveguides and 50 waveguides for sham (control) exposures. The experimental rats were exposed to 2,450‐MHz pulsed microwaves at 800 pps with a 10‐μs pulse width. The pulsed microwaves were square‐wave modulated at 8‐Hz. Whole body calorimetry, thermographic analysis, and power‐meter analysis indicated that microwaves delivered at 0.144 W to each exposure waveguide resulted in an average specific absorption rate (SAR) that ranged from 0.4 W/kg for a 200‐g rat to 0.15 W/kg for an 800‐g rat.

Two hundred male, Sprague‐Dawley rats were assigned in equal numbers to radiation‐exposure and sham‐exposure conditions. Exposure began at 8 weeks of age and continued daily, 21.5 h/day, for 25 months. Animals were bled at regular intervals and blood samples were analyzed for serum chemistries, hematological values, protein electrophoretic patterns, thyroxine, and plasma corticosterone levels. In addition to daily measures of body mass, food and water consumption by all animals, O2 consumption and CO2 production were periodically measured in a sub‐sample (N=18) of each group. Activity was assessed in an open‐field apparatus at regular intervals throughout the study. After 13 months, 10 rats from each group were euthanatized to test for immunological competence and to permit whole‐body analysis, as well as gross and histopathological examinations. At the end of 25 months, the survivors (11 sham‐exposed and 12 radiation‐exposed rats) were euthanatized for similar analyses. The other 157 animals were examined histopathologically when they died spontaneously or were terminated in extremis.
Physiological interaction processes and radio‐frequency energy absorption
Authors: Adair Eleanor R. , Adams Barbara W. , Hartman Sharon K.
Published: February 2006

Because exposure to microwave fields at the resonant frequency may generate heat deep in the body, hyperthermia may result. This problem has been examined in an animal model to determine both the thresholds for response change and the steady‐state thermoregulatory compensation for body heating during exposure at resonant (450 MHz) and supraresonant (2,450 MHz) frequencies. Adult male squirrel monkeys, held in the far field of an antenna within an anechoic chamber, were exposed (10 min or 90 min) to either 450‐MHz or 2,450‐MHz CW fields (E polarization) in cool environments. Whole‐body SARs ranged from 0–6 W/kg (450 MHz) and 0–9 W/kg (2,450 MHz). Colonic and several skin temperatures, metabolic heat production, and evaporative heat loss were monitored continuously. During brief RF exposures in the cold, the reduction of metabolic heat production was directly proportional to the SAR, but 2,450‐MHz energy was a more efficient stimulus than was the resonant frequency. In the steady state, a regulated increase in deep body temperature accompanied exposure at resonance, not unlike that which occurs during exercise. Detailed analyses of the data indicate that temperature changes in the skin are the primary source of the neural signal for a change in physiological interaction processes during RF exposure in the cold. 1992 Wiley‐Liss, Inc.
Radio‐frequency electromagnetic fields associated with cellular‐radio cell‐site antennas
Authors: Petersen R. C. , Testagrossa P. A.
Published: February 2006

Because of a heightened public awareness of issues pertaining to the use of electromagnetic energy, concurrent with a rapid growth of the cellular telephone industry, a study was initiated to characterize the electromagnetic environment associated with typical cellsite antennas. In particular, the radio‐frequency electromagnetic (RF) fields in the vicinity of several antenna towers, ranging in height from 46–82 m, were characterized by measurement. In all cases, the antennas were omnidirectional co‐linear arrays. The maximal power densities considered representative of public exposure were found to be less than 100 μW/m2 (10 nW/cm2) per radio channel. Comparison of measured values with the corresponding values that were calculated from the free‐space transmission formula indicated that the analytical technique is conservative (i.e., overestimates field levels). The measured and corresponding analytical values were found to be well below accepted exposure limits even when extrapolated to simultaneous and continuous operation of the maximal number of transmitters that would be expected to be installed at a cell‐site. Additional measurements were made in the near field of the same antenna type in a roofmounted configuration. At a distance of 0.7 m from the antenna, the maximal power density in the main beam was found to be less than 30 W/m2 (3 mW/cm2) when normalized to sixteen radio channels (the maximal number used on a single antenna) and less than 30 mW/m2 (3μW/m2) at 70 m. In all cases, the effective radiated power (ERP) by each radio channel was 100 W referenced to a half‐wave dipole. This paper describes the instrumentation and measurement techniques used for this study and provides a summary of the results. 1992 Wiley‐Liss, Inc.
A frequency‐dependent finite‐difference time‐domain formulation for induced current calculations in human beings
Authors: Gandhi Om P. , Gao Ben‐Qing , Chen Jin‐Yuan
Published: February 2006

The finite‐difference time‐domain (FDTD) method has been used to calculate SARs and induced currents involving whole‐body or partial‐body exposures of models to spatially uniform or nonuniform (far‐field or near‐field), to sinusoidally varying EM fields, or to transient fields such as those associated with electromagnetic pulses. However, a weakness of the FDTD algorithm is that the dispersion of the tissue's dielectric properties is ignored and frequency‐independent properties are assumed. Although this is permissible for continuous‐wave or narrow‐band irradiation, the results may be highly erroneous for short pulses, in which ultra‐wide bandwidths are involved. In some recent publications, procedures are described for one‐ and two‐dimensional problems for media in which the complex permittivity ϵ * (ω) may be described by a single‐order Debye relaxation equation or a modified version thereof. These procedures based on a convolution integral describing D(t) in terms of E(t) cannot be extended to human tissues for which multiterm Debye relaxation equations must generally be used.

We describe here a new differential‐equation approach that can be used for general dispersive media. We illustrate the use of this approach by one‐ and three‐dimensional examples of media for which ϵ * (ω) is given by a multiterm Debye equation, and for an approximate two‐thirds muscle‐equivalent model of the human body. Based on a single run involving a Gaussian pulse, the frequency‐dependent FDTD [(FD)2TD] method allows calculations of SARs and induced currents at various frequencies by taking the Fourier components of the induced E fields. The (FD)2TD method can also be used to calculate coupling of the short (ultra‐wideband) pulses to the human body. 1992 Wiley‐Liss, Inc.
Microwave sensing of physiological movement and volume change: A review
Authors: Lin James C.
Published: February 2006

The ability non‐invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non‐invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting‐receiving antenna, a set of signal‐conditioning and processing devices, and a display unit. They operate at continuous‐wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001–1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non‐conductive walls. 1992 Wiley‐Liss, Inc.
Microwave radiometry in biomedicine: A reappraisal
Authors: Foster Kenneth R. , Cheever Eric A.
Published: February 2006

Nearly 20 years ago the first papers appeared on biomedical applications of microwave radiometry, and many other papers have since appeared. Yet, despite its unique capabilities, microwave radiometry has so far received only limited acceptance by the medical community, and little commercial success. The chief reasons, we suggest, are the shallow depth of sensing and the difficulty of extracting imaging information from radiometry signals emitted by electrically heterogeneous media. A secondary factor has been the difficulty of validating many proposed clinical applications for the method—in particular, cancer detection. We suggest that microwave radiometry is a viable method of thermal sensing, but its successful applications are likely to be quite different than those that were originally conceived for the technique. 1992 Wiley‐Liss, Inc.
Evaluation of microwave hyperthermia applicators
Authors: Chou C.‐K.
Published: February 2006

Hyperthermia has been used in conjunction with radiation and chemotherapy for cancer treatment. When using electromagnetic heating, applicators are critical components in contact with or in proximity to patients and can be the determining factor for effective and safe treatment. Tissue absorption of electromagnetic energy is determined by many factors. Three cases are shown to illustrate the complexity of microwave heating: 1) The BSD MA‐151 applicator has good center heating on a muscle‐only phantom as shown in the operation manual. When fat slabs of 0.25, 0.5, 1, and 2 cm thick were added, two hot spots near the periphery of the applicator were evident on all fat surfaces, exposed at 631 MHz. At 915 MHz, the heating was elongated on the surface of the models with 0.25‐ and 2‐cm fat, and two hot spots were observed on the 0.5‐ and 1‐cm fat surfaces. 2) Heating patterns of the Clini‐Therm applicators on a muscle‐only phantom, as indicated in the operations guide, are elliptical with their major axes perpendicular to the electric field. However, when a bolus is used, the elliptical pattern is parallel to the E field. 3) Heating patterns in cylindrical structures were studied with inhomogeneous models of limbs. Arm and thigh models consisting of fat, bone, and muscle material were heated with Clini‐Therm L, M, and MS applicators at 915 MHz. In addition to the geometric effect, the results indicated that placing the applicators with E field parallel to the long axis of cylindrical structures can minimize required power, produce less heating of fats and reduce stray radiation. In conclusion, to apply penetrating microwave or other RF fields for tissue heating, one must simulate the clinical exposure conditions as closely as possible to obtain useful heating patterns. 1992 Wiley‐Liss, Inc.
Rat liver foci study on coexposure with 50 Hz magnetic fields and known carcinogens
Authors: Rannug Agneta , Holmberg Bo , Ekström Tomas , Mild Kjell Hansson
Published: February 2006

A study was performed to investigate possible interactions by magnetic fields (MF) with the processes of initiation and promotion of chemically induced preneoplastic lesions in rat liver. Male Sprague‐Dawley rats were subjected to a 70% partial hepatectomy followed after 24 h by i.p. injection of diethylnitrosamine (DENA) as a tumour initiator. Starting one week after the DENA‐treatment phenobarbital (PB) was given to promote growth of enzymatically altered foci of liver cells. MF was applied immediately after the partial hepatectomy and continued until sacrifice after 12 weeks of PB exposure. Homogenous horizontal AC magnetic fields with a frequency of 50 Hz and flux densities of 0.5 μT or 0.5 mT were used. The rats coexposed with MF and DENA plus PB did not gain weight as much as the rats exposed to the chemical agents only. The MF‐exposure also resulted in a slight reduction in size and numbers of the focal lesions. The results suggest an interaction of MF with the processes of chemical carcinogenesis either as a result of stress or depending on effects on the proliferation of preneoplastic cells. © 1993 Wiley‐Liss, Inc.
Determination of the induced ELF electric field distribution in a two layer in vitro system simulating biological cells in nutrient solution
Authors: Wang W. , Litovitz T. A. , Penafiel L. M. , Meister R.
Published: February 2006

In‐vitro studies of biological effects of electromagnetic fields are often conducted with cultured cells either in suspension or grown in a monolayer. In the former case, the exposed medium can be assumed to be homogeneous; however, eventually the cells settle to the bottom of the container forming a two layer system with different dielectric and conductive properties. In the present work the effect of this separation on the electric field distribution is calculated and experimentally measured at selected positions for a commonly used exposure configuration. The settled cell suspension is modeled by a well‐defined two layer system placed in a rectangular container with the base of the container parallel to the direction of the magnetic field. Theoretical calculations based on numerical techniques are done for various two layer systems with different conductivities in each layer. The agreement between the theoretical calculations and the experimental measurements is within ± 1.5 mV/m, or 10% of the maximum induced field when the conductivity of the lower layer is ten times that of the upper layer. This result is well within experimental error. When the thickness of one of the layers is small compared to the thickness of the other layer, it is found that the electric field distribution is essentially that of the homogeneous case. The latter situation corresponds to a typical cell exposure condition. © 1993 Wiley‐Liss, Inc.
Inter‐beat intervals of cardiac‐cell aggregates during exposure to 2.45 GHz CW, pulsed, and square‐wave‐modulated microwaves
Authors: Seaman Ronald L. , Dehaan Robert L.
Published: February 2006

Inter‐beat intervals of aggregated cardiac cells from chicken embryos were studied during 190 s exposures to 2.45 GHz microwaves in an open‐ended coaxial device. Averaged specific‐absorption rates (SARs) and modulation conditions were 1.2–86.9 W/kg continuous‐wave (CW). 1.2–12.2 W/kg pulse modulation (PW, duty cycle ∽ 11%). and 12.0–43.5 W/kg square‐wave modulation (duty cycle = 50%). The inter‐beat interval decreased during microwave exposures at 42.0 W/kg and higher when CW or square‐wave modulation was used, which is consistent with established effects of elevated temperatures. However, increases in the inter‐beat interval during CW exposures at 1.2–12.2 W/kg, and decreases in the inter‐beat interval after PW exposures at 8.4–12.2 W/kg. are not consistent with simple thermal effects. Analysis of variance indicated that SAR. modulation, and the modulation‐SAR interaction were all significant factors in altering the interbeat interval. The latter two factors indicated that the cardiac cells were affected by athermal as well as thermal effects of microwave exposure. © 1993 Wiley‐Liss. Inc.
2D plasmon excitation and nonthermal effects of microwaves on biological membranes
Authors: Fisun O. I.
Published: February 2006

There are several experimental reports that have demonstrated a remarkable increase in conduction of ions along the interface between water and a polar‐lipid monolayer as contrasted with that in a bulk‐water phase. A simple model was developed for the collective ionic modes of a charged spherical membrane that takes the increase into account. Starting from the hydrodynamic equations for surface ions inside and outside a cell, the dispersion relation for intrinsic cellular electrical oscillations was obtained. Properties were calculated for surface‐plasmon modes as well as for a resonant response of a charged membrane bilayer to microwave pumping. © 1993 Wiley‐Liss, Inc.
The effect of moving air on detection of a 60‐Hz electric field
Authors: Stell Mark , Sheppard Asher R. , Adey W. Ross
Published: February 2006

Two potential mechanisms in detection of a 60‐Hz electric field by albino rats were examined: field‐induced movement of the vibrissae and field‐induced vibration of the skin. Specifically, the experiment tested field detection in a moving stream of air designed to mask field‐induced movement of the skin, fur, and vibrissae. Rats were trained to detect electric fields and were then tested at field intensities from 0–25 kV/m rms. As previously reported, rats demonstrate unmistakable behavioral evidence of field detection at all intensities above 7.5 kV/m. After establishing detection in still air, field detection was re‐examined in moving air (average air velocity approximately 2.8–6.8 m/s). The primary result is that the wind produced no change in detection at field intensities above threshold (> 7.5 kV/m). Indeed, at these intensities detection was virtually identical in still and moving air. A secondary finding is that moving air produced statistically significant (P < .05) but apparently contradictory effects on detection when the field intensity was below threshold. On no‐field trials the wind lowered scores (i.e., fewer presses on the field‐off lever); however, on subthreshold field trials, the wind actually increased detection scores (i.e., more presses on the field‐on lever). While this no‐field and subthreshold field result is interesting and deserves further study, we place primary emphasis on the finding that, if the field was detectable in still air, it was also detectable in moving air. This result leads us to believe that movement of the vibrissae, fur, or skin is not likely to be the main mechanism of electric‐field detection in our subjects. © 1993 Wiley‐Liss. Inc.