Effect of non-thermal radiofrequency on body temperature in mice (original) (raw)
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Bioelectromagnetics, 2018
Radiofrequency radiation (RFR) causes heating, which can lead to detrimental biological effects. To characterize the effects of RFR exposure on body temperature in relation to animal size and pregnancy, a series of short-term toxicity studies was conducted in a unique RFR exposure system. Young and old B6C3F1 mice and young, old, and pregnant Harlan Sprague-Dawley rats were exposed to Global System for Mobile Communication (GSM) or Code Division Multiple Access (CDMA) RFR (rats = 900 MHz, mice = 1,900 MHz) at specific absorption rates (SARs) up to 12 W/kg for approximately 9 h a day for 5 days. In general, fewer and less severe increases in body temperature were observed in young than in older rats. SAR-dependent increases in subcutaneous body temperatures were observed at exposures ≥6 W/kg in both modulations. Exposures of ≥10 W/kg GSM or CDMA RFR induced excessive increases in body temperature, leading to mortality. There was also a significant increase in the number of resorptio...
Thermophysiological responses of human volunteers to whole body RF exposure at 220 MHz
Bioelectromagnetics, 2005
Since 1994, our research has demonstrated how thermophysiological responses are mobilized in human volunteers exposed to three radio frequencies, 100, 450, and 2450 MHz. A significant gap in this frequency range is now filled by the present study, conducted at 220 MHz. Thermoregulatory responses of heat loss and heat production were measured in six adult volunteers (five males, one female, aged 24–63 years) during 45 min whole body dorsal exposures to 220 MHz radio frequency (RF) energy. Three power densities (PD = 9, 12, and 15 mW/cm2 [1 mW/cm2 = 10 W/m2], whole body average normalized specific absorption rate [SAR] = 0.045 [W/kg]/[mW/cm2] = 0.0045 [W/kg]/[W/m2]) were tested at each of three ambient temperatures (Ta = 24, 28, and 31 °C) plus Ta controls (no RF). Measured responses included esophageal (Tesoph) and seven skin temperatures (Tsk), metabolic rate (M), local sweat rate, and local skin blood flow (SkBF). Derived measures included heart rate (HR), respiration rate, and total evaporative water loss (EWL). Finite difference-time domain (FDTD) modeling of a seated 70 kg human exposed to 220 MHz predicted six localized ‘hot spots’ at which local temperatures were also measured. No changes in M occurred under any test condition, while Tesoph showed small changes (≤0.35 °C) but never exceeded 37.3 °C. As with similar exposures at 100 MHz, local Tsk changed little and modest increases in SkBF were recorded. At 220 MHz, vigorous sweating occurred at PD = 12 and 15 mW/cm2, with sweating levels higher than those observed for equivalent PD at 100 MHz. Predicted ‘hot spots’ were confirmed by local temperature measurements. The FDTD model showed the local SAR in deep neural tissues that harbor temperature-sensitive neurons (e.g., brainstem, spinal cord) to be greater at 220 than at 100 MHz. Human exposure at both 220 and 100 MHz results in far less skin heating than occurs during exposure at 450 MHz. However, the exposed subjects thermoregulate efficiently because of increased heat loss responses, particularly sweating. It is clear that these responses are controlled by neural signals from thermosensors deep in the brainstem and spinal cord, rather than those in the skin. Bioelectromagnetics 26:448–461, 2005. Published 2005 Wiley-Liss, Inc.
Bioelectromagnetics, 1998
Since 1994, our research has demonstrated how thermophysiological responses are mobilized in human volunteers exposed to three radio frequencies, 100, 450, and 2450 MHz. A significant gap in this frequency range is now filled by the present study, conducted at 220 MHz. Thermoregulatory responses of heat loss and heat production were measured in six adult volunteers (five males, one female, aged 24-63 years) during 45 min whole body dorsal exposures to 220 MHz radio frequency (RF) energy. Three power densities (PD = 9, 12, and 15 mW/cm 2 [1 mW/cm 2 = 10 W/m 2 ], whole body average normalized specific absorption rate
Effect of Radiofrequency Electromagnetic Fields on Thermal Sensitivity in the Rat
International Journal of Environmental Research and Public Health
The World Health Organization and the French Health Safety Agency (ANSES) recognize that the expressed pain and suffering of electromagnetic field hypersensitivity syndrome (EHS) people are a lived reality requiring daily life adaptations to cope. Mechanisms involving glutamatergic N-methyl d-aspartate (NMDA) receptors were not explored yet, despite their possible role in hypersensitivity to chemicals. Here, we hypothesized that radiofrequency electromagnetic field (RF-EMF) exposures may affect pain perception under a modulatory role played by the NMDA receptor. The rats were exposed to RF-EMF for four weeks (five times a week, at 0 (sham), 1.5 or 6 W/kg in restraint) or were cage controls (CC). Once a week, they received an NMDA or saline injection before being scored for their preference between two plates in the two-temperatures choice test: 50 °C (thermal nociception) versus 28 °C. Results in the CC and the sham rats indicated that latency to escape from heat was significantly r...
Does Exposure to a Radiofrequency Electromagnetic Field Modify Thermal Preference in Juvenile Rats?
PLoS ONE, 2014
Some studies have shown that people living near a mobile phone base station may report sleep disturbances and discomfort. Using a rat model, we have previously shown that chronic exposure to a low-intensity radiofrequency electromagnetic field (RF-EMF) was associated with paradoxical sleep (PS) fragmentation and greater vasomotor tone in the tail. Here, we sought to establish whether sleep disturbances might result from the disturbance of thermoregulatory processes by a RF-EMF. We recorded thermal preference and sleep stage distribution in 18 young male Wistar rats. Nine animals were exposed to a low-intensity RF-EMF (900 MHz, 1 V.m 21 ) for five weeks and nine served as non-exposed controls. Thermal preference was assessed in an experimental chamber comprising three interconnected compartments, in which the air temperatures (T a ) were set to 24uC, 28uC and 31uC. Sleep and tail skin temperature were also recorded. Our results indicated that relative to control group, exposure to RF-EMF at 31uC was associated with a significantly lower tail skin temperature (21.6uC) which confirmed previous data. During the light period, the exposed group preferred to sleep at T a = 31uC and the controls preferred T a = 28uC. The mean sleep duration in exposed group was significantly greater (by 15.5%) than in control group (due in turn to a significantly greater amount of slow wave sleep (SWS, +14.6%). Similarly, frequency of SWS was greater in exposed group (by 4.9 episodes.h 21 ). The PS did not differ significantly between the two groups. During the dark period, there were no significant intergroup differences. We conclude that RF-EMF exposure induced a shift in thermal preference towards higher temperatures. The shift in preferred temperature might result from a cold thermal sensation. The change in sleep stage distribution may involve signals from thermoreceptors in the skin. Modulation of SWS may be a protective adaptation in response to RF-EMF exposure.
Long-term and low-thermal biological effects of microwaves
WIT Transactions on Biomedicine and Health, 2005
There is evidence that radio frequencies (RF) and microwaves directly affect living systems, as indicated by in vivo absorption experiments. Evidence is also provided by in vitro studies, revealing effects at various frequencies and intensities, on a number of cellular endpoints, including calcium binding, proliferation and alteration in membrane channels. There is ambiguity, however, about the relative contribution of direct and indirect non-thermal, i.e. lowthermal effects, as well as the possibility of direct low-thermal interactions. In this study, a possible causal link between microwave radiation (radar, cellular phone) and physiological and cellular changes is being evaluated by an epidemiological animal study on 128 rats, for 1.5 year. In order to assess the possible biological long-term effects of microwaves, we selected among others the following blood and hormonal parameters: lymphocytes, monocytes, granulocytes, erythrocytes, platelets, cytokines, corticosterone and ACTH (adrenocorticotrophic hormone). There is lack of knowledge about the biological mechanisms of the exposure to such low-level electromagnetic fields.
Physiological interaction processes and radio-frequency energy absorption
Bioelectromagnetics, 1992
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 O-S, 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. 0 1992 Wiley-Liss, Inc.
Physics in Medicine and Biology, 2013
Human exposure to radio frequency (RF) electromagnetic energy is known to result in tissue heating and can raise temperatures substantially in some situations. Standards for safe exposure to RF do not reflect bio-heat transfer considerations however. Thermoregulatory function (vasodilation, sweating) may mitigate RF heating effects in some environments and exposure scenarios. Conversely, a combination of an extreme environment (high temperature, high humidity), high activity levels and thermally insulating garments may exacerbate RF exposure and pose a risk of unsafe temperature elevation, even for power densities which might be acceptable in a normothermic environment. A high-resolution thermophysiological model, incorporating a heterogeneous tissue model of a seated adult has been developed and used to replicate a series of whole-body exposures at a frequency (100 MHz) which approximates that of human whole-body resonance. Exposures were simulated at three power densities (4, 6 and 8 mW cm −2 ) plus a sham exposure and at three different ambient temperatures (24, 28 and 31 • C). The maximum hypothalamic temperature increase over the course of a 45 min exposure was 0.28 • C and occurred in the most extreme conditions (T amb = 31 • C, PD = 8 mW cm −2 ). Skin temperature increases attributable to RF exposure were modest, with the exception of a 'hot spot' in the vicinity of the ankle where skin temperatures exceeded 39 • C. Temperature increases in internal organs and tissues were small, except for connective tissue and bone in the lower leg and foot. Temperature elevation also was noted in the spinal cord, consistent with a hot spot previously identified in the literature.
A B S T R A C T The mobile communication technology, although integral to our everyday life, has been accounted to suffer negative impacts on the living body via two effects, thermal and non-thermal. The aims of this study were to assess the thermal effects by using Infra-red camera techniques and thermographic analysis and to find out how much electromagnetic fields from mobile phones contribute to increase the skin temperature due to thermal effects from chronic exposure to Global System for Mobile communication (GSM) mobile phone radiation. Eighty female Sprague Dawley rats were employed throughout the experiment, and the animals were dealt into four groups, control, 15, 30 and 60 days respectively (n=20) for 1h/day whole body exposure at SAR levels of 0.048 W/Kg. GSM-like signals at a frequency of 1800 MHz were provided by a signal generator. Thermographic analysis was done by using FLIR Tool software to estimate the changes in skin temperature in different regions of the physical structure. Statistical analysis shows significant changes in skin temperature between unexposed and exposed groups for 15 and 30 days of exposure (P< 0.001). While the skin temperature of 60 days exposure group remained consistent with unexposed group values. Our data suggest that mobile phone radiation at frequency 1800 MHz has a thermal effect represented by skin temperature rises in the whole body. The infra-red image analysis results are anticipated to help change mobile phone users' behavior to minimize the negative effects of mobile phone radiation.
IEEE Transactions on Biomedical Engineering, 2018
− − − − Objective: This study investigated the influence of absorption metrics and averaging schemes on correlation between RF/microwave energy and induced temperature elevation for plane wave exposures. Methods: A voxel-based, anatomically realistic model of the human body was considered. Correlation of electromagnetic fields and temperature increases were evaluated at several frequencies. Both Specific Absorption Rate (SAR) and Volume Absorption Rate (VAR) were considered. Results: The best correlation with temperature increase occurs for exposure durations between 1 and 2 min both for SAR and VAR for most of the 700-to 2700-MHz frequencies considered. In this case, a 1-g mass or 1-cm 3 volume appears to be optimal. However, for VAR, as frequency increases to above 900 MHz, a better correlation is achieved at slightly increased exposure times and volumes. For longer exposures, the maximum correlation coefficient is reduced, and the correlation favors larger averaging mass or volume. At steady-state (30 min), correlation of temperature increase with SAR is maximum for a mass of 9 g for all frequencies considered, whereas the volume for VAR maximum correlation is 15 cm 3 for higher frequencies and 20 cm 3 for lower frequencies. Conclusions: In general, SAR provides a better correlation with temperature compared to VAR for short exposures, while VAR renders better correlations for higher frequencies and longer exposures. Significance: The correlation between electromagnetic absorption and temperature increases has implications in guidelines for limiting human exposure to electromagnetic fields and in biomedical applications such as imaging, sensing, and hyperthermia.