Bioelectromagnetics最新文献

This paper presents a comprehensive measurement-based assessment of radio-frequency (RF) electromagnetic field (EMF) exposure level in a French city. Three types of assessment methods are used to collect measurement data: drive test (DT), spot measurements, and sensor networks. The DT measurements were conducted by a portable spectrum analyzer, i.e., Tektronix RSA 306B, connected to a 3-axis antenna mounted on the roof of the vehicle. DT system continuously recorded frequency-dependent electric field (E-field) values on a pre-defined outdoor route. The spot measurements were done in the same region, covered by DT, with both broadband and frequency-selective systems. Additionally, 19 sensors were installed on streetlamps in the same part of the city to measure the broadband E-field level. The overall statistical analysis on raw data shows good agreement on RF-EMF exposure level from three types of measurements. Then a distance-based moving average method was carried out to remove the random noise in the DT data, where the optimized window size is explored using Kolmogorov-Smirnov test. The smoothed DT data show a good correlation with nearby spot measurement values, as well as with base station antenna (BSA) density. Specific fifth-generation (5G) spot measurements, performed with and without traffic-attracting downloads, demonstrate the impact of beamforming on exposure levels in 5G new radio (NR) bands. Then spot measurements were used to build the exposure map using the kriging method, where the kriging prediction from the trained model is further compared with DT. Furthermore, the temporal variations observed in the sensor network were analyzed in relation to distance from the nearest BSA, revealing an inverse proportional relationship between E-field level and proximity to the nearest BSA. This study shows good reliability in assessing the RF-EMF exposure level using different systems. The advantages and limitations of different systems are also demonstrated by performing the intercomparison between data sets.

In the context of risk communication in mobile radio, a discussion has emerged whether exposure at common load of a base station should be presented in addition to the theoretical maximum, especially with 5G massive-MIMO. However, a reproducible measurement method for instantaneous exposure independent of the utilization of the cell has yet to be developed. To fill this gap, 10 mobile phone use cases were identified, the corresponding data rates were measured and categorized into low (20 Mbps), medium (200 Mbps), and high (600 Mbps) data rates to generate a typical base station load. A measurement method was developed, using iPerf on a user equipment to generate the data rates at a measurement point, while a channel power measurement is used to determine the exposure of all mobile radio services installed. The method was validated at four base stations, considering various factors such as reproducibility in relation to the number of users in the cell, averaging time, and application buffering. The results show the reliability of the method across different times of day and base station loads and that averaging over 30 sweeps provides reproducible exposure results. Consequently, this study presents a validated approach for measuring typical instantaneous exposure in real-world mobile network conditions.

Meta-analyses of epidemiological studies have suggested that Alzheimer's disease (AD) may be linked with exposure to extremely low frequency (ELF) magnetic fields (MF). This is the first study investigating the association of AD with exposure to residential ELF MFs from indoor transformer stations, using a study design that avoids shortcomings of previous studies. All cohort members had lived in buildings with indoor transformer stations. MF exposure was assessed based on the location of their apartment in relation to the transformer room. AD patients were identified from Drug Purchase Register and Drug Reimbursement Register. Out of the 155,562 individuals, 5652 (111,357 person-years of follow-up) living in apartments next to transformer stations were considered as exposed, while 115,772 (2,289,526 person-years of follow-up) individuals living on higher floors of the same buildings were considered as referents. Associations between MF exposure and AD were examined using Cox proportional hazard models. The hazard ratio (HR) was 1.02 (95% confidence interval: 0.85–1.22), indicating that the risk of AD is not associated with residential ELF MFs present in apartments next to transformer stations. The duration of residence did not essentially change the HR. The risk of AD was slightly but not statistically significantly higher (HR 1.22, 95% confidence interval: 0.94–1.57) for those whose residence started before the age of 50 years. The results did not support positive findings from previous studies that have reported a link between AD and occupational or residential MF exposure. Bioelectromagnetics. 00:00–00, 2025.

The widespread deployment of 5G wireless networks alongside existing GSM technologies has increased the need to assess potential biological effects of co-exposure to multiple radiofrequency electromagnetic fields (RF-EMF). This study evaluates the in-vitro impact of simultaneous exposure to 5G-modulated 3.5 GHz and GSM-modulated 1.8 GHz signals on neuronal electrical activity, mitochondrial reactive oxygen species (ROS) production, and cellular stress protein responses in neurons and skin fibroblasts. Primary cortical neurons and human immortalized skin fibroblasts were exposed to RF-EMF at specific absorption rates (SAR) of 1 or 4 W/kg for 15 min or 24 h, respectively. Neuronal activity was analyzed using multi-electrode arrays (MEAs), mitochondrial ROS production was measured using MitoSOX Red, and stress protein activity was assessed using bioluminescence resonance energy transfer (BRET) assays targeting RAS, PML, and HSF1 proteins. The results indicate no significant effects on the mean bursting rate (MBR) or mean firing rate (MFR) of cortical neurons, consistent with previous findings at similar SAR levels. Mitochondrial ROS production in fibroblasts also remained unaffected by RF-EMF co-exposure. BRET assays detected minor variations in the basal activity of RAS and PML and in the maximal efficacy of PMA and As₂O₃ to activate these pathways. However, these effects were small, near the detection threshold, and showed no consistent pattern across different tests or chemical treatments. No change was observed in HSF1 basal activity or responsiveness to MG132. These findings suggest that co-exposure to 5G- and GSM-modulated RF-EMF at SAR levels up to 4 W/kg does not produce conclusive evidence of marked biological effects under the tested conditions. Observed variations, when present, are of low amplitude and likely to fall within the range of experimental variability.

Compliance testing of wireless devices with absorbed power density (APD) limits requires body models that conservatively reproduce the absorption characteristics of human skin. Previous studies indicate that impedance-matching effects are caused by the stratum corneum (SC) layer. The objective of this study is to develop a single macroscopic dielectric model reproducing absorption of electromagnetic fields by the skin up to 110 GHz. The reflection coefficient of the skin of human volunteers was measured at frequencies of 15 to 43 GHz with open waveguide probes, complementing previous data from 45 to 110 GHz. The measurements were made at various regions of the body. The statistical analysis of the results shows that the reflection coefficient in dB follows normal distribution in regions with thin SC, which permits the development of a conservative skin model. In regions with thick SC, for example, the palms, the reflection coefficient is not normally distributed because the thickness of the SC depends on the mechanical stress the hands are exposed to. The measured data allow the derivation of dispersive two-layer models representing absorption and reflection at the skin surface with known uncertainty. The models can be used to conservatively demonstrate compliance with the APD limits of wireless devices in any of the 5G and 6G bands.