Authored by: Niels Kuster
Published on: Jan 18, 2011
In his letter 'Perhaps a Way Forward to Study Fundamental Biological Processes with EMF' published in the BEMS Newsletter 215 (Jul/Aug 2010), Carl Blackman discusses the significance of the publication by Focke et al. (Mutation Research 2010, Vol 683(1-2), pp 74-83) as an important stepping stone for bioelectromagnetic scientists to accelerate research on clarifying the underlying biological mechanisms associated with EMF exposure. As the initiator of this study and as a member of the research team who was responsible for the exposure system, I would like to share my growing concerns about the biased scientific culture within BEMS and to reiterate the value of conducting replications studies.
As Dr. Blackman mentioned, this study was initiated to confirm the experimental results of Ivanscits et al. (Mutation Research 2002,Vol 519, pp 1-13). After the basic findings were confirmed, our objectives were expanded considerably to investigate the positive findings in the Comet assay resulting in a research effort lasting several years. This is the classic approach to advance science that is purely driven by scientific inquiry. Nevertheless, it was unusually difficult to publish our study, whereas a shorter, less comprehensive study that failed to confirm the positive findings was published with relative ease (Maria Scarfí et al. Radiat Res (2005) vol. 164 (3) pp. 270-6). Although some reviews and additional analyses have illuminated uncertainties and gaps in our scientific assessment, the Focke et al. study qualifies and temperes some of the observed results. It answers, to the extent possible, major questions raised in the critiques by clearly defining the conditions under which reproducible ELF-EMF-induced DNA fragmentation can be detected and offers a tentative plan for conducting further studies. In addition it refines its assessment in connection with a possible final understanding of the underlying biological mechanisms.
Importantly, the study confirmed and established this reproducible low-level ELF-MF effect!
In an ideal scientific world and in an ideal scientific journal review process, scientific endeavor is a search for objective knowledge. Yet it all too often seems that many BEMS members allow their conditioned assumptions, prejudices, funding interests or lack of expertise to influence their ability to review or accept positive findings objectively. There is a perceived lack of importance or creativity associated with replication studies and a perception of editor and reviewer bias against such studies. Replication provides verification and/or refutation of previous studies. It is likely that there are false findings in the available literature. Since many studies have relatively small sample size, careful replication would be helpful for extending the generalization of these results to better understand a particular phenomenon. This underscores the necessity for more replications in our field. As scientists, we must better explicate the conditions necessary to promote an unbiased replication tradition in bioelectromagnetic research and open our minds to the many possibilities in science. Specifically:
- Since the biological effects of low level EMF exposures are very weak, i.e., very close to the detection level, they are prone to be affected by artifacts and require meticulous experimental techniques. False positive results can occur, especially if there is little motivation or diligence to investigate potential confounders and artifacts. On the other hand, false negative confirmation results are much easier to achieve, e.g., by only reducing the sensitivity a little. This environment leads to a situation in which poor research is awarded and rewarded. Good research is time consuming because of the many artifacts that need to be eliminated, and therefore, underfunded, risky and underpublished.
- Science is fundamentally conservative even though it is designed to progress continuously, usually in small steps and rarely in big strides. Preeminent labs, however, dominate the frontier of progress through their advances. Many of these labs also dominate the review process, which inevitably leads to less scrutiny of the results conforming to their mindset. Such a conservative bias leads to a vast number of publications that contribute little to the knowledge base because it only confirms previous knowledge. As a consequence, the weight of evidence based on the number of publications might be essentially flawed. The only effective solution is judicious and meticulous replications.
Our society is threatened by these polarizing and accelerating biases, both towards positive findings and, increasingly, towards negative replications. It is in the hands of the Society to allow good science to prevail by:
- promoting science driven by inquisitive scrutiny, not political or funding interests, i.e., by reducing the influence of policymakers in the Society;
- thoroughly scrutinizing the experimental methods of both positive and negative results with the utmost respect to the researchers
- accepting that rigorous studies of low level EMF effects is a very time consuming effort and requires experimental methods of maximized sensitivities beyond routine evaluation techniques;
- rejecting funding for research projects with the purpose of appeasing political or corporate debates.
Understanding the nature of science is an essential tool for assessing the reliability and scope of scientific claims, perceiving the scope of these claims, and making related decisions. But scientific observations, even when reported carefully, can be subject to misinterpretation.
In fact, as author Douglas Allchin notes in his article "Error and the Nature of Science", the data do not necessarily speak for themselves. Scientists interpret the data, and credible scientists may justifiably disagree on the appropriate interpretation of observations. While science deals with facts over values, it can be misinterpreted by those with agendas. Or there can be material, observational, conceptual, or social errors in the reports. View the full article here.
We welcome comments on this article as it relates to Bioelectromagnetics for publication in future newsletters, either anonymously or accredited to the author.
A recent article in Nature reviews how animals perceive magnetic fields. Authored by Kenneth J. Lohmann, a professor in the Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA, email@example.com, the article notes that while the ability to perceive Earth's magnetic field was at one time dismissed as a physical impossibility, it is now known to exist in diverse animals. Despite uncertainty about the actual magnetic field receptors, the author notes that at least two underlying mechanisms exist — sometimes in the same organism.
Kenneth J. Lohmann Q&A: Animal behaviour: Magnetic-field perception Nature 464, 1140-1142 (22 April 2010) | doi:10.1038/4641140a; Published online 21 April 2010
I've enjoyed the "Research Summary" component of the newsletter because of the broader perspective it brings to the scientific publications. Often, there are clues that could help other investigators perform additional experiments to expand the knowledge base in the research area. The summary published by Muehsam and Pilla in a recent issue of the newsletter (#211) has such potential, but their description of historical events and terminology in the second paragraph is not consistent with my understanding. I commend the authors for their work, and hope I can clarify the historical record because it has bearing on the research being described.
As I recall, this line of research began with a report by Cyril Smith (Jafary-Asl et al. J.Biol.Phys. 11:15, 1983) describing biological measurements under magnetic resonance conditions. Subsequently I reported at the 1984 BEMS annual meeting on a calcium ion efflux phenomenon that was both dependent on the frequency of the applied field and the strength of the earth's magnetic field. In that presentation I suggested that it seemed consistent with either a cyclotron or magnetic resonance process because both the oscillating electric and magnetic components were perpendicular to the static magnetic field (MicrowaveNews, Sept 1984, Vol IV, No.7, page 2; Blackman et al., BEMS Vol. 6(1985):327).
At the meeting, Abe Liboff became very excited by our presentation, in part because of work he published in the journal Science in 1984 on cell growth. With my encouragement, he and his colleagues quickly developed a model that he called Ion Cyclotron Resonance, and supported it with a substantial data set.
In 1992, Valery Lednev added an essential component to the model, namely, a model of the possible influence of the intensity of an AC magnetic field oriented parallel to the DC magnetic field, supplemented with experimental data to support the model predictions. Despite some initial skepticism, both Liboff’s ICR model and Lednev's model are widely recognized as landmark achievements in our society that initiated a wide range of work to extend each model to better understand observed experimental results.
One of the first of those efforts came a short time later, when Blanchard and Blackman developed extensive data to test the Lednev model and found it did not predict the details of their biological responses. As a result they developed the Ion Parametric Resonance (IPR) model that did predict the experimental data (BEMS 15:217 and 239, 1994), and made further predictions about additional response that were subsequently confirmed experimentally (FASEB 9:547, 1995). This included a resonance response when the exposure conditions were tuned just for hydrogen ions (Trillo et al., BEMS 17:10, 1996). Subsequently Blackman and colleagues identified the bandwidth of the response for the single ion hydrogen resonance for the IPR model (BEMS 20:5, 1999). Additional reports by Baureus-Koch et al. (BEMS 24:385, 2003) and Sarimov et al. (BEMS 26:631, 2005) independently demonstrated ionic and biological responses, respectively, consistent with the IPR model.
Meanwhile, Lednev and his colleagues continued to successfully test the Lednev model, which they formally named the Parametric Resonance model (PRM) to distinguish it from the other proposed models.
In time, other models were also developed by Zhadin, by Fesenko, by Binhi, and by others (see my memorium for Professor Lednev in NL #206, p6). Obviously, the efforts by so many scientists to develop predictive models indicate there is a great unresolved mystery in this area of weak EMF-induced biological effects. To date, as Muehsam and Pilla emphasize in their summary, no one has found the grand unifying theory in bioelectromagnetics. That is, to date no model developed completely describes the results that have been reported over the entire parameter space that has been tested. This tells us that care must be taken in over-generalizing any model until more is known. But each model contributes an important part of the puzzle if it is supported by experimental data.
Personally, I would like to see a further development of the Meuhsam and Pilla model to provide insight into the experimental results we published in 1996 (Biochem Biophys Res Comm 220:807) showing different biological responses in the same biological system using different orientations from parallel to perpendicular of the AC and Static magnetic fields. I hope their research and that of others continues to help the broader scientific community understand the mechanisms behind the observed biological responses to low intensity electromagnetic fields that have been tantalizing the BEMS scientific community since the late 1960s.
Valič B1, 2, Gajšek P1, Miklavčič D2
1Institute of Non-Ionizing Radiation, Ljubljana, Slovenia
2Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
Summary of research published in Bioelectromagnetics Vol. 30, No. 7, pp 591-599.
In modern medicine, many different prosthetic, therapeutic, diagnostic, or experimental implants are used. With the increasing number of implants, whether active or passive, an important question is raised: do current guidelines protect persons with the implants from the EMF adequately? Can the implant alter the electric and magnetic field distribution inside the human body in such a way that the basic restrictions are exceeded in spite of the fact that reference levels are not? The question of the protection of implanted persons is even more important in the working environment, where the employer is responsible for health and safety at work and must prove that the risks due to the EMF is minimal.
In recent years this question was addressed in a number of reports. But most of the papers deal either with RF fields, the exposure during MR imaging, or with the immunity of the active implants. We were unable to find any publication dealing with the effects of the implant on the current density distribution in the ELF (extreme low frequency) electric and magnetic field exposure situation.
In our study we used numerical modeling to calculate the current density distribution inside a human body with an intramedullary nail simultaneously exposed to ELF (50 Hz) electric and magnetic fields. We used an intramedullary nail in the femur because it is one of the longest implants used in humans. Thus, it is expected to alter the current density distribution significantly. The exposure conditions were corresponding to the reference levels for general public. To evaluate the influence of the implant, the current density distribution in the model with the implant was compared with the current density distribution in the model without the implant.
The results show that for the worst case exposure situation (the electric field is in the inferior to superior direction and the magnetic field in posterior to anterior direction) the implant increases the current density up to 10 times: from 0.9 mAm2 in the model without the implant to 9.5 mAm2 in the model with the implant in the region where the implant is in contact with soft tissue. This increase is significant since, in spite of complying with ICNIRP reference levels for general public, the basic restrictions on current density for general public are exceeded nearly five times. The region, where significant increase in the current density is observed, is however limited: in less than 8 cubic centimeters, ICNIRP basic restrictions are exceeded twice (current density higher than 4 mAm2).
The high increase of the current density means that the existing safety limits do not necessarily protect persons with implants to the same extent as they protect people without implants. The current density might consequentially exceed ICNIRP basic restrictions even though exposure is in compliance with ICNIRP reference levels. Cardiologists, traumatologists and other physicians who implant such implants and patients receiving them should attach importance to understanding of the electric and magnetic field distribution changes inside the human body due to conducting implants. In addition, the knowledge about the possible effects of the implants on the safety of the exposed patients is important for those preparing guidelines and standards about risk assessment and all involved in risk assessment in the working environment, where specific risks due to the effect of the implant should also be taken into account.
Giovanna Del Vecchio1, Alessandro Giuliani1, Mercedes Fernandez1, Pietro Mesirca2, Ferdinando Bersani2, Rosanna Pinto3, Lucia Ardoino3, Giorgio A. Lovisolo3, Luciana Giardino1,4 and Laura Calza1,4
1Department of Veterinary Morphophysiology and Animal Production (DIMORFIPA), Bologna University, Bologna, Italy
2Department of Physics, Bologna University, Bologna, Italy
3Toxicology and Biomedical Sciences Unit, C. R. Casaccia ENEA, Rome, Italy
4INBB, Bologna University, Bologna, Italy
Summary of research published in Biolelectromagnetics, Vol. 30, No. 7, pp 564-572.
The incidence of neurodegenerative diseases is progressively increasing, partially due to the increase in life expectancy. However, pathogenesis of many neurodegenerative diseases including Alzheimer disease (AD) is still obscure. Among potential environmental risk factors for AD, exposures to electromagnetic fields (EMF) have received much attention, particularly extremely low frequency electromagnetic fields (ELF-EMF). The main approach in these studies has been the systematic review and meta-analysis of published epidemiological studies.
In this, and in related studies (Neuroscience Letters, 2009, 455:173-7), we investigated the effect of continuous exposure to a global system for mobile telecommunications (GSM) modulated 900MHz signal on in vitro neuronal systems, with the specific aim to investigate if exposure to RF-EMF might act as co-stressor of well known neurotoxic agents.
We believe that co-administration of potential stressors is still a poorly explored field for both bioelectromagnetism and biology of neurodegenerative diseases. Therefore, we based our approaches to the exposure of cell systems to well-established chemical neurotoxic challengers together with RF-EMF. In order to compare the co-stressor effect on cell populations which differ in vulnerability to chemical neurotoxic challengers, we also used more than one neuronal in vitro system. We investigated beta-amyloid toxicity, as a model for AD, glutamate toxicity, as a model for excitoxic lesion operating in many conditions, and H2O2 toxicity, as a model for oxidative stress. The studies have been carried out in a SN56 cholinergic cell line and in rat primary cortical neurons. In vitro continuous exposure to 900MHz GSM–EMF guaranteed an average SAR of 1W/kg.
Compared to other studies focused on neural in vitro systems, we used a highly controlled exposure system provided with specific software to guarantee blind experiments, continuous monitoring and feedback regulation of net power and recording of all exposure and temperature data. RF exposure affected neither proliferation in control culture nor cell death due to glutamate or 25-35 beta-amyloid fragment. On the contrary, cell death rate due to oxidative stress (H2O2) was increased by RF co-exposure in SN56 cells, but not in primary neurons. Cholinergic neurons derived from the medial septum as SN56 cells, are intrinsically more sensitive than primary cortical neurons to nitric oxide excess, which is induced by in vitro culturing. These data support the view that oxidative stress might be the underlying mechanism responsible for the reported cellular effects of RF radiation. They also indicate that RF radiation could be dangerous in selected conditions and on specific neuronal populations.
Tarek Said and Vasundara V. Varadan
Microwave and Optics Laboratory for Imaging & Characterization, University of Arkansas, Fayetteville, Arkansas, 72701 USA
Summary of research published in Biolelectromagnetics, Vol. 30, No. 8, pp. 669-677.
This paper is a theoretical study of a complex problem, predicting the dielectric properties of breast fat tissue in terms of its gross composition. Currently, microwave imaging has offered hope for safer diagnostic and tumor detection; however further experimental work is still needed.
Experimental studies of breast tissue permittivity in literature are available only at frequencies below 20 GHz and only at a few discrete selected frequencies. Debye and Cole-Cole relaxation models are frequently used to extrapolate the measurement to provide continuous data at higher microwave frequencies. Relaxation models serve essentially to parameterize the dielectric data without interpreting wide variations in the measurement data from one sample to another.
The approach used in this paper is an attempt to partly explain the wide variations in the measured complex permittivity data for breast fat tissue at microwave frequencies. In the microwave frequency region, tissue permittivity can be determined mainly using the data on the free water. Past research has focused on the variation of dielectric properties of a biological tissue as a function of its water content. But the distribution of water in the tissue is also a strong contributor to the effective permittivity of the tissue. In this study we take into account both the concentration and distribution of water to model the dielectric permittivity of the tissue. This is an important area of study because water content and distribution is an indicator of tissue health.
Motivated by the overall need to improve breast cancer detection and characterization and our standing interest in advancing medical microwave imaging, we have proposed computational models of the dielectric permittivity of breast fat tissue varying with water content and distribution. In our study, we look at 1-D (fat layers interspersed with layers of water), 2-D (water tubules and fat tubules coated with water), and 3-D (water globules and fat globules coated with water) all of which show variations in dielectric permittivity for the same volume content of water. The 1-D and 2-D models may find application for different types of tissues such as skin, muscle or collagenous tissues.
The T-matrix multiple scattering formalism has been successful to compute effective properties of inhomogeneous media for arbitrary inclusion geometry. It is a good method to predict the effective permittivity of a heterogeneous material when either the concentration or the size of the suspended constituents is large. It has not been applied to model the dielectric permittivity of biological tissues. This paper proposes an application of this theory to fat/water mixtures to explain the dependence of the complex permittivity on water content as well as water distribution. The effective permittivity, obtained for different shape of water inclusions, is compared with experimental data from literature. Our results indicate that water distribution is another factor that contributes to the differences in the dielectric permittivity of samples of fat that have the same water content. Our model is a small but positive step to develop robust models for microwave biomedical diagnostics.
Yuen Yuen Chen and Andrew Wood
Faculty of Life and Social Sciences, Cellular Neuroscience Laboratory, Brain Sciences Institute, Swinburne University of Technology, Hawthorn, VIC, Australia
Summary of research published in Biolelectromagnetics, Vol. 30, No. 7, pp 583-590.
The computed Specific Absorption Rate (SAR) in both in-vitro and in-vivo preparations has often been used as an indicator of whether observed radiofrequency (RF) effects can be due to a thermal or a non-thermal mechanism. However, because of the high variation in SAR in many of these preparations, the diffusion or convection of heat makes the local changes in temperature difficult to estimate. This is particularly true in complex tissue samples such as brain slices or in whole brain. Although it is possible to penetrate tissue with fluoroptic probes, this produces damage and can only measure from a limited number of locations.
The method described in this paper involves a commonly-used fluorescent dye, Rhodamine B, which is readily taken up by tissue and whose fluorescent intensity is markedly decreased as temperature rises. The intensity is mapped in 3D by confocal microscopy, which, in essence, produces a ‘stack’ of 2D ‘slices’ at successive depths within the sample. By taking images at various times before, during, and after RF exposure, the change of temperature at various locations in the sample was followed. The paper also reports on initial calibration of the dye in non-living or fixed samples against temperature estimated by fluoroptic probes. From this calibration, the fluorescent intensity fell by 3.4+/-0.2 % per degree Celsius. The RF energy was supplied to a purpose-built exposure chamber in which simultaneous confocal images are obtained and in which the SAR distribution has previously been extensively modeled. Changes in fluorescence reveal a temperature gradient within the sample (which was approximately 0.6 x 0.6 x 0.1 mm, with a ‘stack’ of 15 x 2D images each 6.5 microns thick), which was not anticipated from SAR measurements.
We anticipate that this work will contribute to a better understanding of SAR in relation to localized changes in temperature in biological samples. Ongoing work is examining the use of Rhodamine B in fresh (non-fixed) tissue to determine the initial rate of temperature rise in the first few seconds after the RF power has been turned on compared with what is predicted by thermal modeling.
Andrew B. Gapeyev, Elena N. Mikhailik, and Nikolay K. Chemeris
Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russia
Summary of research published in Bioelectromagnetics, Vol. 30, No. 6, pp. 454-461.
Under typical environmental conditions, open and self-organizing biological systems are exposed to a wide spectrum of multiple-frequency and modulated electromagnetic fields (EMFs). We observed that there is no information in the literature about mechanisms describing the reaction of biological systems to multiple-frequency electromagnetic exposure on the background of increasing pharmacological load. In typical experiments, features and regularities of biological effects of modulated EMFs are not accurately defined, despite the fact that the existence of modulation can lead to significant changes in biological effect patterns compared to the effects of continuous radiation with the same carrier frequencies. Physical and chemical mechanisms of biological effects of modulated and continuous electromagnetic fields can be different and are probably connected to the influence on quasi-periodic processes that dominate in formation, stability, development, and functioning of all living systems. We considered that studying modulated EMF could be done by subjecting the object simultaneously to a set of harmonic signals. By selecting type and frequencies of modulation we may be able to differentially influence particular systems of a cell or an organism.
Earlier, using various cellular models in vitro, we showed that pulse-modulated, extremely high-frequency electromagnetic radiation (EHF EMR) can essentially modify cellular functions, with the effects being critically dependent on combination of carrier and modulation frequencies. Modulated EHF EMR (42.2±0.2 GHz, incident power density of 0.1 mW/cm2, modulation frequency of 0.095±0.005 Hz) inhibited a motor activity of unicellular protozoa Paramecium caudatum [Gapeyev et al., 1994]. The effect was named a "double resonance", as it had a quasi-resonance dependence on both carrier and modulation frequencies, and was not observed under the influence of continuous EHF EMR. Modulated EHF EMR (41.95 GHz, 0.05 mW/cm2, 20-min exposure duration) inhibited or activated the production of reactive oxygen species by isolated peritoneal neutrophils of mice depending on modulation frequencies [Gapeyev et al., 1998]. We suggested that calcium-dependent intracellular signal transduction pathways activated at neutrophils' respiratory burst are selective to both carrier and modulation frequencies of EHF EMR.
The present study was performed to determine features of biological effects of low-intensity modulated EHF EMR using a model of acute non-specific inflammation in laboratory mice of NMRI outbreed stock. Our recent data showed that the model of acute zymosan-induced paw edema in mice is very sensitive to the influence of low-intensity EHF EMR. Single whole-body exposure of animals to continuous EHF EMR for 20 min reduced the exudative edema of inflamed paw on average by 20% compared to the control at intensities of 0.1-0.7 mW/cm2 and frequencies from the range of 42.2-42.6 GHz [Gapeyev et al., 2008]. We have now demonstrated that application of different modulation frequencies from the range of 0.03-100 Hz did not lead to considerable changes in the effect level caused by effective carrier frequency of 42.2 GHz. When specific combinations of "ineffective" carrier frequencies of 43.0 and 61.22 GHz, and modulation frequencies of 0.07-0.1 and 20-30 Hz were applied, the anti-inflammatory effect showed synergistic enhancement in narrow ranges of modulation frequencies.
Considering an increasing level of anthropogenic complex-modulated EMF, the results we obtained showing synergistic enhancement of EHF EMR effects at the certain combination of carrier and modulation frequencies have special importance. In narrow bands of modulation frequencies, certain carrier frequencies become biologically active, which by themselves did not previously cause appreciable biological action. This could mean that in a real environment of biological systems, considering the nonlinear interaction of inherent oscillation modes, there can be the combination of frequencies selectively influencing certain systems of cells and an organism as a whole. The efficacy and direction of such action is ambiguous, as it strongly depends on the functional status of a biological object that can be changed by application of various pharmacological treatments. In some cases, there are additive and synergistic effects that strengthen the action of medical drugs [Gapeyev et al., 2008]. This has undoubted potential advantage for clinical application through possibly lowering a dosage of applied drugs to reduce their side effects. It is obvious that the further detailed studies are necessary for the purpose of determining key molecular and cellular mechanisms responsible for realization of effects of multiple-frequency and modulated EMFs.
The work was supported by the Russian Foundation for Basic Research (project # 08-04-90000) and the Russian Science Support Foundation.
Ki Chang Nam1, Ju Hyung Lee2, Hyung Wook Noh2, Eun Jong Cha3, Nam Hyun Kim2, 4, Deok Won Kim2, 4
1Korea Electrotechnology Reserch Institute, Ansan, Republic of Korea
2Graduate Program in Biomedical Engineering, Yonsie University, Seoul, Republic of Korea
3Department of Biomedical Engineering, Chungbuk National University, Cheongjoo, Republic of Korea
4Department of Medical Engineering, Yonsei University College of Medicine, Seoul, Republic of Korea
Summary of research published in Bioelectromagnetics, Volume 30, No. 8, pp.641-650.
Why is this research area important to Bioelectromagnetics?
With the rapidly increasing number of cellular phone users, the number of people with self-attributed electromagnetic hypersensitivity (EHS) who complain of various subjective symptoms, such as headache, insomnia, nervousness, distress, fatigue, and short-term memory loss, has increased as well. In a population based survey, the prevalence of EHS was reported to be 1.5% in Sweden, 3.2% in California, 4% in the UK, 5% in Switzerland, and 8-10% in Germany. EHS could not only deteriorate the quality of individual patients’ lives, but also cause an increase of social expenses for health care. Therefore, the objective of our research was to determine whether EHS results from actual physiological changes or psychological causes.
What was already done about this topic prior to this research?
For EHS related studies, three general methods have been utilized to investigate the origins of the EHS. The first is to measure the physiological variables such as heart rate, respiration rate or/and blood pressure etc. during sham and real exposures for the EHS or/and non-EHS group. The second is to survey those subjective symptoms during sham and real exposures for the EHS or/and non-EHS group. The third method is to determine perception accuracies during sham and real exposures for the EHS or/and non-EHS group. Most research has been carried out using one or two methods with GSM phones, but not with Code Division Multiple Access (CDMA) phones.
What did this work contribute to the subject?
We simultaneously investigated the physiological parameters, subjective symptoms, and EMF perception accuracy using CDMA phones for the EHS and non-EHS groups. We concluded that 300 mW exposures from CDMA phones for one half-hour did not have any effects on physiological variables such as the heart, respiration rate, or low frequency power/high frequency power (LFP/HFP), which was used as an index for the balance of autonomic nervous system in either group. It also did not produce any subjective symptoms in either group. As for EMF perception, there was no evidence that the EHS group’s perception of EMF was better than the non-EHS group. The possibility of a delayed exposure effect in the EMF perception was observed in the EHS group, but not in the non-EHS group.
We found two additional important findings in our study. While responding to questions regarding symptoms and EMF perception, 10 of the 37 subjects showed considerably varied skin conductance because of increased sweat secretion during sham exposure resulting from an excited sympathetic nervous system. Despite this, we still believe that it is a good parameter for investigating the autonomic nervous system if there are no such inquiries for subjective symptoms or EMF perception involved in the test.
Second, even though the experiments were performed during the day, drowsiness was observed in approximately half of all subjects because the subjects were in comfortable postures for more than an hour in a quiet room. If the examiner noticed a subject’s drowsiness, he made a noise to wake the subject up, resulting in sleep deprivation. We observed monotonically increased LFP/HFP at each exposure stage during sham exposure in both groups. Such a continuous increase is assumed to have been caused by sleep deprivation during the 64-min experiment. It has been reported that sleep deprivation could increase LFP and LFP/HFP. The usage of heart rate or HRV with unwanted drowsiness may falsely indicate the effects of RF radiation by mobile phones on the autonomic nervous system.