Human exposure at two radio frequencies (450 and 2450 MHz): similarities and differences in physiological response.
ABSTRACT Thermoregulatory responses of heat production and heat loss were measured in two different groups of seven adult volunteers (males and females) during 45-min dorsal exposures of the whole body to 450 or 2450 MHz continuous-wave radio frequency (RF) fields. At each frequency, two power densities (PD) were tested at each of three ambient temperatures (T(a) = 24, 28, and 31 degrees C) plus T(a) controls (no RF). The normalized peak surface specific absorption rate (SAR), measured at the location of the subject's center back, was the same for comparable PD at both frequencies, i.e., peak surface SAR = 6.0 and 7.7 W/kg. No change in metabolic heat production occurred under any exposure conditions at either frequency. The magnitude of increase in those skin temperatures under direct irradiation was directly related to frequency, but local sweating rates on back and chest were related more to T(a) and SAR. Both efficient sweating and increased local skin blood flow contributed to the regulation of the deep body (esophageal) temperature to within 0.1 degrees C of the baseline level. At both frequencies, normalized peak SARs in excess of ANSI/IEEE C95.1 guidelines were easily counteracted by normal thermophysiological mechanisms. The observed frequency-related response differences agree with classical data concerning the control of heat loss mechanisms in human beings. However, more practical dosimetry than is currently available will be necessary to evaluate realistic human exposures to RF energy in the natural environment.
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ABSTRACT: Background The effects of electromagnetic waves (EMWs) on humans and their relationship with various disorders have been investigated. We aimed to investigate the effects of exposure to different frequencies of EMWs in various durations in a mouse epilepsy model induced by pentylenetetrazole (PTZ). Material and Methods A total of 180 4-week-old male mice weighing 25-30 g were used in this study. Each experimental group consisted of 10 mice. They were exposed to 900, 700, 500, 300, and 100 MHz EMWs for 20 hours, 12 hours and 2 hours. Following electromagnetic radiation exposure, 60 mg/kg of PTZ was injected intraperitoneally to all mice. Each control was also injected with PTZ without any exposure to EMW. The latency of initial seizure and most severe seizure onset were compared with controls. Results The shortest initial seizure latency was noted in the 12-hour group, followed by the 700 MHz. The mean initial seizure latencies in the 2-hour EMW exposed group was significantly shorter compared to that in the 12- and 20-hour groups. There was no significant difference between 12- and 20-hour EMW exposed groups. There was a significant difference between control and 2- and 10-hour EMW exposed groups. No statistically significant differences were noted in mean latencies of the most severe seizure latency, following 20-, 12-, and 2- hour EMW exposed groups and control groups. Conclusions Our findings suggest that acute exposure to EMW may facilitate epileptic seizures, which may be independent of EMW exposure time. This information might be important for patients with epilepsy. Further studies are needed.Medical science monitor basic research. 01/2013; 19:141-5.
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ABSTRACT: Mobile phones generate microwave radiation which is absorbed by exposed tissue and converted into heat. It may cause detrimental health effects. The aim of the experiment was to check if exposure to EMF emitted by mobile phone influenced the tympanic temperature. Human volunteer study was performed on ten healthy young men, aged 22.1±4.7 years, examined three times: 1. on a day with 2×60 min of no exposure (sham day), 2. on a day with continuous, 60 min exposure and 60 min of no exposure, 3. on a day with intermittent exposure (4×15 min "on" and 4×15 min "off"). Exposure was generated by mobile phone (frequency 900 MHz, SAR 1.23 W/kg). The study was double-blind, performed under controlled conditions (at 24°C and 70% humidity). The tympanic temperature (T(ty)) was monitored every 10 sec by a thermistor probe placed close to the aural canal membrane in the ear opposite the one in contact with mobile phone (contralateral position). Multivariate repeated-measures analysis of variance was used to calculate the results. The mean T(ty) in the whole group during continuous exposure was significantly higher than during sham exposure (p = 0.0001). During intermittent exposure the temperature was lower than during sham day (difference was up to 0.11°C). Within an hour after continuous exposure, T(ty) was higher by 0.03°C and after intermittent exposure T(ty) was lower by 0.18°C in comparison with sham day. Two hours after exposure T(ty) was significantly lower (p = 0.0001) than after sham exposure (0.06°C and 0.26°C respectively). The trends in T(ty) during experiment differed significantly in relation to exposure conditions (p < 0.05). The results of this analysis indicate that the physiological response to EMF exposure from mobile phone was mostly related to type of exposure (continuous or intermittent).International Journal of Occupational Medicine and Environmental Health 03/2012; 25(2):145-50. · 1.31 Impact Factor
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ABSTRACT: A multiscale modelling approach for designing polymers is presented in this work. Here, the desired properties of a polymer is given as input in the polymer design problem, computer aided molecular design (CAMD) algorithm using group contribution plus models (macro-meso scale) gives out the polymer repeat unit structures satisfying the desired properties as output. The arrangement of polymer repeat unit structures to form a polymer chain and the properties corresponding to the generated polymer are studied in micro-scale approach. A case study using this multiscale approach is presented in this paper.01/2009;