milimetrski valovi (27 od skupno 1310 raziskav)
"The fifth generation (5G) for wireless communication is about to be deployed worldwide in spite of no thorough studies being made on the potential risks to human health and the environment. The implementation seems to be driven mainly by business interests, not considering mounting public anxiety on the associated risks. In Estonia, an appeal on a moratorium was signed by 1,122 subjects, forcing a hearing in the Social Affairs Commission and the Environment Commission of Estonian Parliament on June 4, 2019. The hearing lasted for 1 h and 40 min. The whole hearing may be found on the web. It clearly demonstrated that decision‑making bodies base their decisions and act on expert statements that tend to be biased and formed by a cartel of members instead of their own science‑based evaluation. Thus, the hearing revealed a lack of knowledge among the Commission members on the risks involved with the use of 5G wireless communication that is exemplified herein. This may create negative consequences for human health and the environment in the future."
"Extreme broadband wireless devices operating above 10 GHz may transmit data in bursts of a few milliseconds to seconds. Even though the time- and area-averaged power density values remain within the acceptable safety limits for continuous exposure, these bursts may lead to short temperature spikes in the skin of exposed people. In this paper, a novel analytical approach to pulsed heating is developed and applied to assess the peak-to-average temperature ratio as a function of the pulse fraction α (relative to the averaging time [INCREMENT]T; it corresponds to the inverse of the peak-to-average ratio). This has been analyzed for two different perfusion-related thermal time constants (τ1 = 100 s and 500 s) corresponding to plane-wave and localized exposures. To allow for peak temperatures that considerably exceed the 1 K increase, the CEM43 tissue damage model, with an experimental-data-based damage threshold for human skin of 600 min, is used to allow large temperature oscillations that remain below the level at which tissue damage occurs. To stay consistent with the current safety guidelines, safety factors of 10 for occupational exposure and 50 for the general public were applied. The model assumptions and limitations (e.g., employed thermal and tissue damage models, homogeneous skin, consideration of localized exposure by a modified time constant) are discussed in detail. The results demonstrate that the maximum averaging time, based on the assumption of a thermal time constant of 100 s, is 240 s if the maximum local temperature increase for continuous-wave exposure is limited to 1 K and α ≥ 0.1. For a very low peak-to-average ratio of 100 (α ≥ 0.01), it decreases to only 30 s. The results also show that the peak-to-average ratio of 1,000 tolerated by the International Council on Non-Ionizing Radiation Protection guidelines may lead to permanent tissue damage after even short exposures, highlighting the importance of revisiting existing exposure guidelines."
"The study examined the effects of millimeter electromagnetic waves at a frequency of 130 GHz corresponding to the molecular absorption and radiation spectra of NO and O2 with the total exposition time of 6 h on tumor morphogenesis in 3- and 6-month-old tumor-prone BALB/c mice of both sexes. In experimental mice exposed to electromagnetic radiation, the development of cancer process was slowed down throughout the observation period; moreover, no macroscopic signs of the tumors were revealed. However, in contrast to control mice, experimental animals demonstrated the formation of pathological reactions reflected by hepatic biochemical indices accompanied by the development of dystrophic and microcirculatory alterations in the liver tissue."
"Insects are continually exposed to Radio-Frequency (RF) electromagnetic fields at different frequencies. The range of frequencies used for wireless telecommunication systems will increase in the near future from below 6 GHz (2 G, 3 G, 4 G, and WiFi) to frequencies up to 120 GHz (5 G). This paper is the first to report the absorbed RF electromagnetic power in four different types of insects as a function of frequency from 2 GHz to 120 GHz. A set of insect models was obtained using novel Micro-CT (computer tomography) imaging. These models were used for the first time in finite-difference time-domain electromagnetic simulations. All insects showed a dependence of the absorbed power on the frequency. All insects showed a general increase in absorbed RF power at and above 6 GHz, in comparison to the absorbed RF power below 6 GHz. Our simulations showed that a shift of 10% of the incident power density to frequencies above 6 GHz would lead to an increase in absorbed power between 3–370%."
"The spread of radiofrequency electromagnetic fields (RF-EMF) is rising and health effects are still under investigation. RF-EMF promote oxidative stress, a condition involved in cancer onset, in several acute and chronic diseases and in vascular homeostasis. Although some evidences are still controversial, the WHO IARC classified RF-EMF as "possible carcinogenic to humans", and more recent studies suggested reproductive, metabolic and neurologic effects of RF-EMF, which are also able to alter bacterial antibiotic resistance. In this evolving scenario, although the biological effects of 5G communication systems are very scarcely investigated, an international action plan for the development of 5G networks has started, with a forthcoming increment in devices and density of small cells, and with the future use of millimeter waves (MMW). Preliminary observations showed that MMW increase skin temperature, alter gene expression, promote cellular proliferation and synthesis of proteins linked with oxidative stress, inflammatory and metabolic processes, could generate ocular damages, affect neuro-muscular dynamics. Further studies are needed to better and independently explore the health effects of RF-EMF in general and of MMW in particular. However, available findings seem sufficient to demonstrate the existence of biomedical effects, to invoke the precautionary principle, to define exposed subjects as potentially vulnerable and to revise existing limits. An adequate knowledge of pathophysiological mechanisms linking RF-EMF exposure to health risk should also be useful in the current clinical practice, in particular in consideration of evidences pointing to extrinsic factors as heavy contributors to cancer risk and to the progressive epidemiological growth of noncommunicable diseases."
"The subject, a 39-yr-old active duty man, participated in a test of a 95-GHz energy beam designed to heat the skin. He had delayed presentation of raised, erythematous, nonpruritic, nonpainful areas at five of the exposure sites where the skin temperature exceeded 54°C. All wheals resolved within 2 h of the exposures."
"After exposure of R. sphaeroides, grown under anaerobic conditions upon illumination, to EMI (51.8GHz and 53.0GHz) for 15min an increase of specific growth rate by ~1.2-fold, in comparison with control (non-irradiated cells), was obtained. However, the effect of EMI depends on the duration of irradiation: the exposure elongation up to 60min caused the delay of the growth lag phase and the decrease specific growth rate by ~1.3-fold, indicating the bactericidal effect of EMI. H2 yield of the culture, irradiated by EMI for 15min, determined during 72h growth, was ~1.2-fold higher than H2 yield of control cells, whereas H2 production by cultures, irradiated by EMI for 60min was not observed during 72h growth. This difference in the effects of extremely high frequency EMI indicates a direct effect of radiation on the membrane transfer and the enzymes of these bacteria. Moreover, EMI increased DCCD-inhibited H(+) fluxes across the bacterial membrane and DCCD-sensitive ATPase activity of membrane vesicles, indicating that the proton FoF1-ATPase is presumably a basic target for extremely high frequency EMI related to H2 production by cultures."
"The MMW/2dG co-treatment did not alter the keratinocyte ATP content, but it did slightly alter the transcriptome, which reflected the capacity of MMW to interfere with the bioenergetic stress response. The RT-PCR-based validation confirmed 6 MMW-sensitive genes (SOCS3, SPRY2, TRIB1, FAM46A, CSRNP1 and PPP1R15A) during the 2dG treatment. These 6 genes encoded transcription factors or inhibitors of cytokine pathways, which raised questions regarding the potential impact of long-term or chronic MMW exposure on metabolically stressed cells."
"The significant cellular targets for MMW effects could be water, cell plasma membrane, and genome. The model for the MMW interaction with bacteria is suggested; a role of the membrane-associated proton FOF1-ATPase, key enzyme of bioenergetic relevance, is proposed. The consequences of MMW interaction with bacteria are the changes in their sensitivity to different biologically active chemicals, including antibiotics. Novel data on MMW effects on bacteria and their sensitivity to different antibiotics are presented and discussed; the combined action of MMW and antibiotics resulted with more strong effects. These effects are of significance for understanding changed metabolic pathways and distinguish role of bacteria in environment; they might be leading to antibiotic resistance in bacteria."
"During the exposure to MMWs and gradual bath heating at a rate of 0.04°C/s (2.4°C/min), the ganglionic neurons exhibited similar dose-dependent hyperpolarization of the plasma membrane and decrease in the action potential amplitude. However, narrowing of the action potential half-width during MMW irradiation at 4 mW/cm(2) was 5 times more pronounced compared with that during equivalent bath heating of 0.6°C. Even more dramatic difference in the effects of MMW irradiation and bath heating was noted in the firing rate, which was suppressed at all applied MMW power densities and increased in a dose-dependent manner during gradual bath heating. The mechanism of enhanced narrowing of action potentials and suppressed firing by MMW irradiation, compared with that by gradual bath heating, is hypothesized to involve specific coupling of MMW energy with the neuronal plasma membrane."
"However, a heat shock control did not mimic exactly the MMW effect, suggesting a slight but specific electromagnetic effect under hyperthermia conditions (34 genes differentially expressed). By RT-PCR, we analyzed the time course of the transcriptomic response and 7 genes have been validated as differentially expressed: ADAMTS6, NOG, IL7R, FADD, JUNB, SNAI2 and HIST1H1A. Our data evidenced a specific electromagnetic effect of MMW, which is associated to the cellular response to hyperthermia. This study raises the question of co-exposures associating radiofrequencies and other environmental sources of cellular stress."
"The nonthermal biological effects of millimeter waves have been mainly attributed to the interaction with biological membranes. Several data on biomimetic membrane systems seem to support this conclusion. In this paper a mechanistic hypothesis is evaluated to explain such an interaction taking into account experimental NMR data on deuterium-labeled phospholipid vesicles."
"Changes of the direction of vesicle movement are demonstrated, which occur only during irradiation with a "switch on" of the effect. This MMW-induced effect was observed at a larger extent on giant vesicles prepared with negatively charged phospholipids. The monitoring of induced-by-irradiation temperature variation and numerical dosimetry indicate that the observed effects in vesicle movement cannot be attributed to local heating."
"Millimeter waves significantly affect the polar interface of the membrane causing a decrease of the heavy water quadrupole splitting. This effect is as important as inducing the transition from the fluid to the gel phase when the membrane exposure occurs in the neighborhood of the transition point. On the molecular level, the above effect can be well explained by membrane dehydration induced by the radiation."
"In this case, a decrease in the water membrane permeability of the irradiated samples was observed. We advance the hypothesis that both the above effects may be explained in terms of a change of the polarization states of water induced by the radiation, which causes a partial dehydration of the membrane and consequently a greater packing density (increased membrane rigidity)."
"Non thermal (NT) effect of direct radiation 4 Hz-modulated 90-160 GHz of Millimeter Waves (MMW) and preliminary MMW-treated physiological solution (PS) influence were studied on snail isolated neuron, rat's brain tissue hydration and skin penetration. It was shown that the 4 Hz-modulated low intensity 90-160 GHz MMW direct radiation and MMW-treated PS leads to on single neuron shrinkage."
"The enhancement of the CA reaction rate was observed at a lesser extent on liposomes with a larger diameter and, in turn with leaflets less bent. The different packing of the phospholipid bilayer-due to the higher curvature-could be a critical factor in eliciting membrane permeability changes indicating a possible role for water molecules bound to functional groups in the glycerol region. Since numerical dosimetry indicates that the temperature rise during the exposure was negligible, the observed effects cannot be attributed to heating of the samples."
"Exposure to a 94 GHz irradiation induced a statistically significant increase in the calcium spiking. When co-cultured with neuronal cells in the 3D co-culture skin model, changes in the calcium spiking in neuronal cells depended on the MMW input power. Further, the 94 GHz irradiation caused ATP secretion by keratincytes."
"CRIP2, PLXND1, PTX3, SERPINF1, and TRPV2, were confirmed as differentially expressed after 6 h of exposure. To the best of our knowledge, this is the first large-scale study reporting on potential gene expression modification associated with MMW radiation used in wireless communication applications."
"We conclude that these radiations may have a significant effect on reproductive system of male rats, which may be an indication of male infertility."
"This study used slices of cortical tissue to evaluate the MMW effects on individual pyramidal neurons under conditions mimicking their in vivo environment. The applied levels of MMW power are three orders of magnitude below the existing safe limit for human exposure of 1 mW cm(-2). Surprisingly, even at these low power levels, MMWs were able to produce considerable changes in neuronal firing rate and plasma membrane properties. At the power density approaching 1 microW cm(-2), 1 min of MMW exposure reduced the firing rate to one third of the pre-exposure level in four out of eight examined neurons. The width of the action potentials was narrowed by MMW exposure to 17% of the baseline value and the membrane input resistance decreased to 54% of the baseline value across all neurons. These effects were short lasting (2 min or less) and were accompanied by MMW-induced heating of the bath solution at 3 degrees C. Comparison of these results with previously published data on the effects of general bath heating of 10 degrees C indicated that MMW-induced effects cannot be fully attributed to heating and may involve specific MMW absorption by the tissue. Blocking of the intracellular Ca(2+)-mediated signaling did not significantly alter the MMW-induced neuronal responses suggesting that MMWs interacted directly with the neuronal plasma membrane."
"Many but not all observed cellular responses to MMW were similar to thermally induced effects. For example, cell exposure to a 94 GHz field induced nitric oxide production in some morphologically distinct neuronal cells that could not be reproduced by thermal heating of the cells up to 42 degrees C."
"Physical changes of vesicles, i.e. elongation, induced diffusion of fluorescent dye di-8-ANEPPS, and increased attractions between vesicles are demonstrated. These effects are reversible and occur only during irradiation with a "switch on" of the effect requiring a short time. Since the average temperature change was very small the effects could not be attributed to thermal mechanisms. We assume that the interaction of MMW with lipid membrane leads to changes at the membrane-water interface, where charged and dipolar residues are located."
"Result shows that the chronic exposure to these radiations causes DNA double-strand break (head and tail length, intensity and tail migration) and a significant decrease in GPx and SOD activity (p = or<0.05) in brain cells, whereas catalase activity shows significant increase in the exposed group of brain samples as compared with control (p = or<0.001). In addition to these, PKC decreased significantly in whole brain and hippocampus (p < 0.05). All data are expressed as mean +/- standard deviation. We conclude that these radiations can have a significant effect on the whole brain."
"MMW irradiation had time-dependent elevation effect on water SEC and SAR, which was accompanied by the increase of H(2)O(2) formation in it. We suggest that the MMW-induced vibration of water dipole molecules caused the non thermal changes of physicochemical properties of DW and PS, which promote the formation of H(2)O(2) in water."
"MMW, in the 52-78 GHz frequency range, act as stress factor on the cells that survive in a non-steady low-mitogenetic metabolic state."
"Here we review data, which provide evidence that non-thermal microwave effects do exist and may play a significant role. This evidence is based on research at all biological levels, from cell-free systems through cells, tissues and organs, to animal and human organisms."