RESUMEN
OBJECTIVE: To use improved methods to address the question of whether acute exposure to radio-frequency (RF) electromagnetic fields (RF-EMF) affects early (80-200â¯ms) sensory and later (180-600â¯ms) cognitive processes as indexed by event-related potentials (ERPs). METHODS: Thirty-six healthy subjects completed a visual discrimination task during concurrent exposure to a Global System for Mobile Communications (GSM)-like, 920â¯MHz signal with peak-spatial specific absorption rate for 10â¯g of tissue of 0â¯W/kg of body mass (Sham), 1â¯W/kg (Low RF) and 2â¯W/kg (High RF). A fully randomised, counterbalanced, double-blind design was used. RESULTS: P1 amplitude was reduced (pâ¯=â¯.02) and anterior N1 latency was increased (pâ¯=â¯.04) during Exposure compared to Sham. There were no effects on any other ERP latencies or amplitudes. CONCLUSIONS: RF-EMF exposure may affect early perceptual (P1) and preparatory motor (anterior N1) processes. However, only two ERP indices, out of 56 comparisons, were observed to differ between RF-EMF exposure and Sham, suggesting that these observations may be due to chance. SIGNIFICANCE: These observations are consistent with previous findings that RF-EMF exposure has no reliable impact on cognition (e.g., accuracy and response speed).
Asunto(s)
Cognición/efectos de la radiación , Campos Electromagnéticos , Potenciales Evocados Visuales/efectos de la radiación , Percepción Visual/efectos de la radiación , Adolescente , Adulto , Estudios Cruzados , Discriminación en Psicología/efectos de la radiación , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
BACKGROUND: The aim of this study was to quantify RF-EMF exposure applying a tested protocol of RF-EMF exposure measurements using portable devices with a high sampling rate in different microenvironments of Switzerland, Ethiopia, Nepal, South Africa, Australia and the United States of America. METHOD: We used portable measurement devices for assessing RF-EMF exposure in 94 outdoor microenvironments and 18 public transport vehicles. The measurements were taken either by walking with a backpack with the devices at the height of the head and a distance of 20-30â¯cm from the body, or driving a car with the devices mounted on its roof, which was 170-180â¯cm above the ground. The measurements were taken for about 30â¯min while walking and about 15-20â¯min while driving in each microenvironment, with a sampling rate of once every 4â¯s (ExpoM-RF) and 5â¯s (EME Spy 201). RESULTS: Mean total RF-EMF exposure in various outdoor microenvironments varied between 0.23â¯V/m (non-central residential area in Switzerland) and 1.85â¯V/m (university area in Australia), and across modes of public transport between 0.32â¯V/m (bus in rural area in Switzerland) and 0.86â¯V/m (Auto rickshaw in urban area in Nepal). For most outdoor areas the major exposure contribution was from mobile phone base stations. Otherwise broadcasting was dominant. Uplink from mobile phone handsets was generally very small, except in Swiss trains and some Swiss buses. CONCLUSIONS: This study demonstrates high RF-EMF variability between the 94 selected microenvironments from all over the world. Exposure levels tended to increase with increasing urbanity. In most microenvironments downlink from mobile phone base stations is the most relevant contributor.
Asunto(s)
Campos Electromagnéticos , Exposición a Riesgos Ambientales/análisis , Monitoreo del Ambiente/métodos , Ondas de Radio , Australia , Conducción de Automóvil , Humanos , Nepal , Sudáfrica , Suiza , CaminataRESUMEN
BACKGROUND: Spatial and temporal distribution of radiofrequency electromagnetic field (RF-EMF) levels in the environment is highly heterogeneous. It is thus not entirely clear how to monitor spatial variability and temporal trends of RF-EMF exposure levels in the environment in a representative and efficient manner. The aim of this study was to test a monitoring protocol for RF-EMF measurements in public areas using portable devices. METHODS: Using the ExpoM-RF devices mounted on a backpack, we have conducted RF-EMF measurements by walking through 51 different outdoor microenvironments from 20 different municipalities in Switzerland: 5 different city centers, 5 central residential areas, 5 non-central residential areas, 15 rural residential areas, 15 rural centers and 6 industrial areas. Measurements in public transport (buses, trains, trams) were collected when traveling between the areas. Measurements were conducted between 25th March and 11th July 2014. In order to evaluate spatial representativity within one microenvironment, we measured two crossing paths of about 1km in length in each microenvironment. To evaluate repeatability, measurements in each microenvironment were repeated after two to four months on the same paths. RESULTS: Mean RF-EMF exposure (sum of 15 main frequency bands between 87.5 and 5,875MHz) was 0.53V/m in industrial zones, 0.47V/m in city centers, 0.32V/m in central residential areas, 0.25V/m non-central residential areas, 0.23V/m in rural centers and rural residential areas, 0.69V/m in trams, 0.46V/m in trains and 0.39V/m in buses. Major exposure contribution at outdoor locations was from mobile phone base stations (>80% for all outdoor areas with respect to the power density scale). Temporal correlation between first and second measurement of each area was high: 0.89 for total RF-EMF, 0.90 for all five mobile phone downlink bands combined, 0.51 for all five uplink bands combined and 0.79 for broadcasting. Spearman correlation between arithmetic mean values of the first path compared to arithmetic mean of the second path within the same microenvironment was 0.75 for total RF-EMF, 0.76 for all five mobile phone downlink bands combined, 0.55 for all five uplink bands combined and 0.85 for broadcasting (FM and DVB-T). CONCLUSIONS: This study demonstrates that microenvironmental surveys using a portable device yields highly repeatable measurements, which allows monitoring time trends of RF-EMF exposure over an extended time period of several years and to compare exposure levels between different types of microenvironments.
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Campos Electromagnéticos , Exposición a la Radiación , Monitoreo de Radiación/métodos , Monitoreo de Radiación/instrumentación , Ondas de Radio , SuizaRESUMEN
Personal radio frequency electromagnetic field (RF-EMF) exposure, or exposimetry, is gaining importance in the bioelectromagnetics community but only limited data on personal exposure is available in indoor areas, namely schools, crèches, homes, and offices. Most studies are focused on adult exposure, whereas indoor microenvironments, where children are exposed, are usually not considered. A method to assess spatial and temporal indoor exposure of children and adults is proposed without involving the subjects themselves. Moreover, maximal possible daily exposure is estimated by combining instantaneous spatial and temporal exposure. In Belgium and Greece, the exposure is measured at 153 positions spread over 55 indoor microenvironments with spectral equipment. In addition, personal exposimeters (measuring EMFs of people during their daily activities) captured the temporal exposure variations during several days up to one week at 98 positions. The data were analyzed using the robust regression on order statistics (ROS) method to account for data below the detection limit. All instantaneous and maximal exposures satisfied international exposure limits and were of the same order of magnitude in Greece and Belgium. Mobile telecommunications and radio broadcasting (FM) were most present. In Belgium, digital cordless phone (DECT) exposure was present for at least 75% in the indoor microenvironments except for schools. Temporal variations of the exposure were mainly due to variations of mobile telecommunication signals. The exposure was higher during daytime than at night due to the increased voice and data traffic on the networks. Total exposure varied the most in Belgian crèches (39.3%) and Greek homes (58.2%).