Microwaves from UMTS/GSM mobile phones induce long-lasting inhibition of 53BP1/gamma-H2AX DNA repair foci in human lymphocytes

We have recently described frequency-dependent effects of mobile phone microwaves (MWs) of global system for mobile communication (GSM) on human lymphocytes from persons reporting hypersensitivity to electromagnetic fields and healthy persons. Contrary to GSM, universal global telecommunications system (UMTS) mobile phones emit wide-band MW signals. Hypothetically, UMTS MWs may result in higher biological effects compared to GSM signal because of eventual "effective" frequencies within the wideband. Here, we report for the first time that UMTS MWs affect chromatin and inhibit formation of DNA double-strand breaks co-localizing 53BP1/gamma-H2AX DNA repair foci in human lymphocytes from hypersensitive and healthy persons and confirm that effects of GSM MWs depend on carrier frequency. Remarkably, the effects of MWs on 53BP1/gamma-H2AX foci persisted up to 72 h following exposure of cells, even longer than the stress response following heat shock. The data are in line with the hypothesis that the type of signal, UMTS MWs, may have higher biological efficiency and possibly larger health risk effects compared to GSM radiation emissions. No significant differences in effects between groups of healthy and hypersensitive subjects were observed, except for the effects of UMTS MWs and GSM-915 MHz MWs on the formation of the DNA repair foci, which were different for hypersensitive (P < 0.02[53BP1]//0.01[gamma-H2AX]) but not for control subjects (P > 0.05). The non-parametric statistics used here did not indicate specificity of the differences revealed between the effects of GSM and UMTS MWs on cells from hypersensitive subjects and more data are needed to study the nature of these differences.     

Review of possible modulation-dependent biological effects of radiofrequency fields

The biological effects of modulated radiofrequency (RF) electromagnetic fields have been a subject of debate since early publications more than 30 years ago, suggesting that relatively weak amplitude-modulated RF electromagnetic fields have specific biological effects different from the well-known thermal effects of RF energy. This discussion has been recently activated by the increasing human exposure to RF fields from wireless communication systems. Modulation is used in all wireless communication systems to enable the signal to carry information. A previous review in 1998 indicated that experimental evidence for modulation-specific effects of RF energy is weak. This article reviews recent studies (published after 1998) on the biological effects of modulated RF fields. The focus is on studies that have compared the effects of modulated and unmodulated (continuous wave) RF fields, or compared the effects of different kinds of modulations; studies that used only one type of signal are not included. While the majority of recent studies have reported no modulation-specific effects, there are a few interesting exceptions indicating that there may be specific effects from amplitude-modulated RF fields on the human central nervous system. These findings warrant follow-up studies.     

No influence on selected parameters of human visual perception of 1970 MHz UMTS-like exposure

In recent years several studies regarding possible effects of radio frequency (RF) electromagnetic fields (EMFs) on cognitive brain function were reported. In many of these studies on awake humans the working tasks were presented visually to the test subjects, e.g., on a computer screen. Therefore, the question of where in the chain of visual perception, brain processing and response a possible effect could be induced seems to be of interest. In this study, possible effects of exposure to a generic 1.97 GHz UMTS-like signal on human visual perception were investigated in a double blinded, crossover study including 58 healthy volunteer subjects (29 male, 29 female), aged 29 +/- 5.1 years (mean +/- SD). Each test subject underwent a battery of four different clinical tests three times (two different exposure levels and sham exposure) to assess selected parameters of visual perception. The generic signals applied to the subjects' head represented the RF emissions of an UMTS mobile phone under constant receiving conditions and the under condition of strongly varying transmit power, i.e., the signal envelope contained low frequency components. In the high exposure condition the resulting average exposure of the test subjects in the cortex of the left temporal lobe of the brain was 0.63 W/kg (1 g averaged SAR) and 0.37 W/kg (10 g averaged SAR). Low exposure condition was one tenth of high exposure and sham was at least 50 dB (corresponding to a factor of 100,000) below low exposure. Statistical evaluation of the obtained test results revealed no statistically significant differences in the investigated parameters of visual perception between the exposure conditions and sham exposure.     

Cognitive function and symptoms in adults and adolescents in relation to rf radiation from UMTS base stations

There is widespread public concern about the potential adverse health effects of mobile phones in general and their associated base stations in particular. This study was designed to investigate the acute effects of radio frequency (RF) electromagnetic fields (EMF) emitted by the Universal Mobile Telecommunication System (UMTS) mobile phone base stations on human cognitive function and symptoms. Forty adolescents (15-16 years) and 40 adults (25-40 years) were exposed to four conditions: (1) sham, (2) a Continuous Wave (CW) at 2140 MHz, (3) a signal at 2140 MHz modulated as UMTS and (4) UMTS at 2140 MHz including all control features in a randomized, double blinded cross-over design. Each exposure lasted 45 min. During exposure the participants performed different cognitive tasks with the Trail Making B (TMB) test as the main outcome and completed a questionnaire measuring self reported subjective symptoms. No statistically significant differences between the UMTS and sham conditions were found for performance on TMB. For the adults, the estimated difference between UMTS and sham was -3.2% (-9.2%; 2.9%) and for the adolescents 5.5% (-1.1%; 12.2%). No significant changes were found in any of the cognitive tasks. An increase in 'headache rating' was observed when data from the adolescents and adults were combined (P = 0.027), an effect that may be due to differences at baseline. In conclusion, the primary hypothesis that UMTS radiation reduces general performance in the TMB test was not confirmed. However, we suggest that the hypothesis of subjective symptoms and EMF exposure needs further research.     

No effect of an UMTS mobile phone-like electromagnetic field of 1.97 GHz on human attention and reaction time

Several studies in the past reported influences of electromagnetic emissions of GSM phones on reaction time in humans. However, there are currently only a few studies available dealing with possible effects of the electromagnetic fields emitted by UMTS mobile phones. In our study, 40 healthy volunteers (20 female, 20 male), aged 26.0 years (range 21-30 years) underwent four different computer tests measuring reaction time and attention under three different UMTS mobile phone-like exposure conditions (two exposure levels plus sham exposure). Exposure of the subjects was accomplished by small helical antennas operated close to the head and fed by a generic signal representing the emissions of a UMTS mobile phone under constant receiving conditions as well as under a condition of strongly varying transmit power. In the high exposure condition the resulting peak spatial average exposure of the test subjects in the cortex of the left temporal lobe of the brain was 0.63 W/kg (min. 0.25 W/kg, max. 1.49 W/kg) in terms of 1 g averaged SAR and 0.37 W/kg (min. 0.16 W/kg, max. 0.84 W/kg) in terms of 10 g averaged SAR, respectively. Low exposure condition was one-tenth of high exposure and sham was at least 50 dB below low exposure. Statistical analysis of the obtained test parameters showed that exposure to the generic UMTS signal had no statistically significant immediate effect on attention or reaction. Therefore, this study does not provide any evidence that exposure of UMTS mobiles interferes with attention under short-term exposure conditions.     

Effects of mobile phone electromagnetic fields on an auditory order threshold task

The effect of acute exposure to radio frequency electromagnetic fields (RF EMF) generated by mobile phones on an auditory threshold task was investigated. 168 participants performed the task while exposed to RF EMF in one testing session (either global system for mobile communication (GSM) or unmodulated signals) while in a separate session participants were exposed to sham signals. Lateralization effects were tested by exposing participants either on the left side or on the right side of the head. No significant effect of exposure to RF EMF was detected, suggesting that acute exposure to RF EMFs does not affect performance in the order threshold task.     

Effects of weak mobile phone - electromagnetic fields (GSM, UMTS) on well-being and resting EEG

Modern mobile phones emit electromagnetic fields (EMFs) ranging from 900 to 2000 MHz which are suggested to have an influence on well-being, attention and neurological parameters in mobile phone users. To date most studies have investigated Global System for Mobile Communications (GSM)-EMF and only very few studies were concerned with Universal Mobile Telecommunications System (UMTS)-EMF. Consequently, we tested the effects of both types of EMF, 1950 MHz UMTS (SAR 0.1 and 1 W/kg) and pulsed 900 MHz GSM (1 W/kg), on well-being and vigilance-controlled resting electroencephalogram (eyes closed) in 15 healthy, right-handed subjects. A double-blind, randomised, crossover application of the test procedure was used. Neither the UMTS- nor the GSM-EMF produced any significant changes in the measured parameters compared to sham exposure. The results do not give any evidence for a deleterious effect of the EMF on normal healthy mobile phone users.     

Induction of an adaptive response in human blood lymphocytes exposed to radiofrequency fields: influence of the universal mobile telecommunication system (UMTS) signal and the specific absorption rate

The induction of an adaptive response (AR) was examined in human peripheral blood lymphocytes exposed to non-ionizing radiofrequency fields (RF). Cells from nine healthy human volunteers were stimulated for 24h with phytohaemagglutinin and then exposed for 20h to an adaptive dose (AD) of a 1950MHz RF UMTS (universal mobile telecommunication system) signal used for mobile communications, at different specific absorption rates (SAR) of 1.25, 0.6, 0.3, and 0.15W/kg. This was followed by treatment of the cells at 48h with a challenge dose (CD) of 100ng/ml mitomycin C (MMC). Lymphocytes were collected at the end of the 72h total culture period. The cytokinesis-block method was used to record the frequency of micronuclei (MN) as genotoxicity end-point. When lymphocytes from six donors were pre-exposed to RF at 0.3W/kg SAR and then treated with MMC, these cells showed a significant reduction in the frequency of MN, compared with the cells treated with MMC alone; this result is indicative of induction of AR. The results from our earlier study indicated that lymphocytes that were stimulated for 24h, exposed for 20h to a 900MHz RF GSM (global system for mobile communication) signal at 1.25W/kg SAR and then treated with 100ng/ml MMC, also exhibited AR. These overall data suggest that the induction of AR depends on RF frequency, type of the signal and SAR. Further characterization of RF-induced AR is in progress.     

Comment: a biological guide for electromagnetic safety: the stress response

Questions of safety of electromagnetic (EM) fields should be based on relevant biological properties, i.e., specific cellular reactions to potentially harmful stimuli. The stress response is a well documented protective reaction of plant and animal cells to a variety of environmental threats, and it is stimulated by both extremely low frequency (ELF) and radio frequency (RF) EM fields. It involves activation of DNA to initiate synthesis of stress proteins. Thermal and non-thermal stimuli affect different segments of DNA and utilize different biochemical pathways. However, both ELF and RF stimulate the same non-thermal pathway. Since the same biochemical reactions are stimulated in different frequency ranges with very different specific absorption rates (SARs), SAR level is not a valid basis for safety standards. Studies of EM field interactions with DNA and with model systems provide insight into a plausible mechanism that can be effective in ELF and RF ranges.     

Radiofrequency radiation at 1950 MHz (UMTS) does not affect key cellular endpoints in neuron-like PC12 cells

In this study, rat pheochromocytoma (PC12) cells were exposed, as a model of neuron-like cells, to 1950 MHz radiofrequency (RF) radiation with a signal used by the 3G wireless technology of the Universal Mobile Telecommunications System (UMTS) to assess possible adverse effects. RF exposure for 24 h at a specific absorption rate (SAR) of 10 W/kg was carried out in a waveguide system under accurately controlled environmental and dosimetric parameters. DNA integrity, cell viability, and apoptosis were investigated as cellular endpoints relevant for carcinogenesis and other diseases of the central nervous system. Very sensitive biological assays were employed to assess the effects immediately after RF exposure and 24 h later, as demonstrated by the cellular response elicited in PC12 cells using positive control treatments provided for each assay. In our experimental conditions, 24 h of RF exposure at a carrier frequency and modulation scheme typical of a UMTS signal was not able to elicit any effect in the selected cellular endpoints in undifferentiated PC12 cells, despite the application of a higher SAR value than those applied in the majority of the studies reported in the literature.     

Guidance for exposure design of human studies addressing health risk evaluations of mobile phones

Conflicting results have recently emerged from human provocation studies that addressed the possible health hazards of radio frequency (RF) field exposure from mobile phones. Different findings may have resulted from exposures that are poorly defined and difficult to compare. The aim of this study was to develop guidelines to facilitate the development of exposure systems for human volunteer studies which lead to reproducible results and which provide maximum relevance with respect to the assessment of the safety of mobile technology. The most important exposure parameters are discussed such as the signal, field distribution, and field strength, as well as the minimum requirements for the setup and dosimetry.     

Effects of modulated microwave radiation at cellular telephone frequency (1.95 GHz) on X-ray-induced chromosome aberrations in human lymphocytes in vitro

The case for a DNA-damaging action produced by radiofrequency (RF) signals remains controversial despite extensive research. With the advent of the Universal Mobile Telecommunication System (UMTS) the number of RF-radiation-exposed individuals is likely to escalate. Since the epigenetic effects of RF radiation are poorly understood and since the potential modifications of repair efficiency after exposure to known cytotoxic agents such as ionizing radiation have been investigated infrequently thus far, we studied the influence of UMTS exposure on the yield of chromosome aberrations induced by X rays. Human peripheral blood lymphocytes were exposed in vitro to a UMTS signal (frequency carrier of 1.95 GHz) for 24 h at 0.5 and 2.0 W/kg specific absorption rate (SAR) using a previously characterized waveguide system. The frequency of chromosome aberrations was measured on metaphase spreads from cells given 4 Gy of X rays immediately before RF radiation or sham exposures by fluorescence in situ hybridization. Unirradiated controls were RF-radiation- or sham-exposed. No significant variations due to the UMTS exposure were found in the fraction of aberrant cells. However, the frequency of exchanges per cell was affected by the SAR, showing a small but statistically significant increase of 0.11 exchange per cell compared to 0 W/kg SAR. We conclude that, although the 1.95 GHz signal (UMTS modulated) does not exacerbate the yield of aberrant cells caused by ionizing radiation, the overall burden of X-ray-induced chromosomal damage per cell in first-mitosis lymphocytes may be enhanced at 2.0 W/kg SAR. Hence the SAR may either influence the repair of X-ray-induced DNA breaks or alter the cell death pathways of the damage response.     

Cellular effects of electromagnetic fields

Studies at the cellular level are needed to reveal the cellular and molecular biological mechanisms underlying the biological effects and possible health implications of non-ionising radiation, such as extremely low frequency (ELF) magnetic fields (MFs) and radiofrequency (RF) fields. Our research group has studied the effects of 50 Hz ELF MFs (caused by power lines and electric devices) and 872 MHz or 900 MHz RFs (emitted by mobile phones and their base stations) on cellular ornithine decarboxylase activity, cell cycle kinetics, cell proliferation, and necrotic or apoptotic cell death. For RFs, pulse-modulated (217 Hz modulation frequency corresponding a global system for mobile communication-type signal) or continuous wave (unmodulated) signals were used. To expose the cell cultures to MFs or RFs, specially developed exposure systems were used, where levels of electromagnetic field exposure and the conditions of cell culture could be precisely controlled. A coexposure approach was used in many studies, i.e. the cell cultures were exposed to other stressors in addition to MFs or RFs. Ultraviolet radiation, serum deprivation, or fresh medium addition, were used as co-exposures. The results presented in this short review show that the effects of mere MFs or RF on cell culture models are quite minor, but that various co-exposure approaches warrant additional study.     

Combining near‐ and far‐field exposure for an organ‐specific and whole‐body RF‐EMF proxy for epidemiological research: A reference case

A framework for the combination of near‐field (NF) and far‐field (FF) radio frequency electromagnetic exposure sources to the average organ and whole‐body specific absorption rates (SARs) is presented. As a reference case, values based on numerically derived SARs for whole‐body and individual organs and tissues are combined with realistic exposure data, which have been collected using personal exposure meters during the Swiss Qualifex study. The framework presented can be applied to any study region where exposure data is collected by appropriate measurement equipment. Based on results derived from the data for the region of Basel, Switzerland, the relative importance of NF and FF sources to the personal exposure is examined for three different study groups. The results show that a 24‐h whole‐body averaged exposure of a typical mobile phone user is dominated by the use of his or her own mobile phone when a Global System for Mobile Communications (GSM) 900 or GSM 1800 phone is used. If only Universal Mobile Telecommunications System (UMTS) phones are used, the user would experience a lower exposure level on average caused by the lower average output power of UMTS phones. Data presented clearly indicate the necessity of collecting band‐selective exposure data in epidemiological studies related to electromagnetic fields. Bioelectromagnetics 34:366–374, 2013. © 2012 Wiley Periodicals, Inc.     

Effects of weak mobile phone - electromagnetic fields (GSM, UMTS) on event related potentials and cognitive functions

Modern mobile phones emit electromagnetic fields (EMF) ranging from 900 to 2000 MHz which are suggested to have an influence on well-being, attention and neurological parameters in mobile phone users. Until now most studies have investigated Global System for Mobile Communications (GSM)-EMF and only very few studies have focused on Universal Mobile Telecommunications System (UMTS)-EMF. Therefore, we tested the effects of both types of unilaterally presented EMF, 1950 UMTS (0.1 and 1 W/kg) and pulsed 900 MHz GSM (1 W/kg), on visually evoked occipital P100, the P300 of a continuous performance test, auditory evoked central N100 and the P300 during an oddball task as well as on the respective behavioral parameters, reaction time and false reactions, in 15 healthy, right handed subjects. A double-blind, randomized, crossover application of the test procedure was used. Neither the UMTS- nor the GSM-EMF produced any significant changes in the measured parameters compared to sham exposure. The results do not give any evidence for a deleterious effect of the EMF on normal healthy mobile phone users.     

Biophysical limits on athermal effects of RF and microwave radiation

Using biophysical criteria, I show that continuous radiofrequency (RF) and microwave radiation with intensity less than 10 mW/cm(2) are unlikely to affect physiology significantly through athermal mechanisms. Biological systems are fundamentally noisy on the molecular scale as a consequence of thermal agitation and are noisy macroscopically as a consequence of physiological functions and animal behavior. If electromagnetic fields are to significantly affect physiology, their direct physical effect must be greater than that from the ubiquitous endogenous noise. Using that criterion, I show that none of a set of interactions of weak fields, which I argue is nearly complete on dimensional grounds, can affect biology on the molecular scale. Moreover, I conclude that such weak fields are quite unlikely to generate significant effects in their interactions with larger biological elements such as cells. In the course of that analysis, I examine important special examples of electromagnetic interactions: "direct" interactions where biology is modified simply by the motion of charged elements generated by the electric field; resonance interactions; the effects of electrostrictive forces and induced dipole moments; and modifications of radical pair recombination probabilities. In each case, I show that it is unlikely that low intensity fields can generate significant physiological consequences.     

Exposure to ELF magnetic and ELF-modulated radiofrequency fields: the time course of physiological and cognitive effects observed in recent studies (2001-2005)

In 2002, we published a review of the cognitive and physiological effects of extremely low frequency magnetic fields (ELF MFs) and ELF-modulated radiofrequency fields associated with mobile phones. Since the original preparation of that review, a significant number of studies have been published using techniques such as electroencephalography, event-related potentials and positron emission tomography to investigate electromagnetic field effects upon human physiology and various measures of performance (cognitive, perceptual, behavioral). We review these recent studies, and when effects were observed, we reference the time course of observed effects (immediate or delayed). In our concluding remarks, we discuss a number of variables that are not often considered in human bioelectromagnetics studies, such as personality, individual differences and the specific laterality of ELF MF and mobile phone exposure over the brain. We also consider the sensitivity of various physiological assays and performance measures in the study of biological effects of electromagnetic fields.     

Effects of continuous and intermittent exposure to RF fields with a wide range of SARs on cell growth, survival, and cell cycle distribution

To examine the biological effects of radio frequency (RF) electromagnetic fields in vitro, we have examined the fundamental cellular responses, such as cell growth, survival, and cell cycle distribution, following exposure to a wide range of specific absorption rates (SAR). Furthermore, we compared the effects of continuous and intermittent exposure at high SARs. An RF electromagnetic field exposure unit operating at a frequency of 2.45 GHz was used to expose cells to SARs from 0.05 to 1500 W/kg. When cells were exposed to a continuous RF field at SARs from 0.05 to 100 W/kg for 2 h, cellular growth rate, survival, and cell cycle distribution were not affected. At 200 W/kg, the cell growth rate was suppressed and cell survival decreased. When the cells were exposed to an intermittent RF field at 300 W/kg(pk), 900 W/kg(pk) and 1500 W/kg(pk) (100 W/kg(mean)), no significant differences were observed between these conditions and intermittent wave exposure at 100 W/kg. When cells were exposed to a SAR of 50 W/kg for 2 h, the temperature of the medium around cells rose to 39.1 degrees C, 100 W/kg exposure increased the temperature to 41.0 degrees C, and 200 W/kg exposure increased the temperature to 44.1 degrees C. Exposure to RF radiation results in heating of the medium, and the thermal effect depends on the mean SAR. Hence, these results suggest that the proliferation disorder is caused by the thermal effect.     

DNA strand breaks are not induced in human cells exposed to 2.1425 GHz band CW and W-CDMA modulated radiofrequency fields allocated to mobile radio base stations

We conducted a large-scale in vitro study focused on the effects of low level radiofrequency (RF) fields from mobile radio base stations employing the International Mobile Telecommunication 2000 (IMT-2000) cellular system in order to test the hypothesis that modulated RF fields may act as a DNA damaging agent. First, we evaluated the responses of human cells to microwave exposure at a specific absorption rate (SAR) of 80 mW/kg, which corresponds to the limit of the average whole body SAR for general public exposure defined as a basic restriction in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. Second, we investigated whether continuous wave (CW) and Wideband Code Division Multiple Access (W-CDMA) modulated signal RF fields at 2.1425 GHz induced different levels of DNA damage. Human glioblastoma A172 cells and normal human IMR-90 fibroblasts from fetal lungs were exposed to mobile communication frequency radiation to investigate whether such exposure produced DNA strand breaks in cell culture. A172 cells were exposed to W-CDMA radiation at SARs of 80, 250, and 800 mW/kg and CW radiation at 80 mW/kg for 2 and 24 h, while IMR-90 cells were exposed to both W-CDMA and CW radiations at a SAR of 80 mW/kg for the same time periods. Under the same RF field exposure conditions, no significant differences in the DNA strand breaks were observed between the test groups exposed to W-CDMA or CW radiation and the sham exposed negative controls, as evaluated immediately after the exposure periods by alkaline comet assays. Our results confirm that low level exposures do not act as a genotoxicant up to a SAR of 800 mW/kg.     

No effects of short‐term exposure to mobile phone electromagnetic fields on human cognitive performance: A meta‐analysis

During recent years, a large number of studies on the effects of electromagnetic fields emitted by cellular mobile phones on human cognitive performance have been carried out. However, the results have been ambiguous. We carried out the current meta‐analysis in order to investigate the impact of electromagnetic fields emitted by mobile phones on human cognition. Seventeen studies were included in the meta‐analysis as they fulfill several requirements such as single‐ or double‐blind experimental study design, and documentation of means and standard deviations of dependent variables. The meta‐analysis was carried out as a group comparison between exposed and non‐exposed subjects. No significant effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) mobile phones were found. Cognitive abilities seem to be neither impaired nor facilitated. Results of the meta‐analysis suggest that a substantial short‐term impact of high frequency electromagnetic fields emitted by mobile phones on cognitive performance can essentially be ruled out. Bioelectromagnetics 33:159–165, 2012. © 2011 Wiley Periodicals, Inc.