siva mrena (30 od skupno 1243 raziskav)
"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."
A young engineer developed bilateral cataract few days after exposure to high microwave energy while working on a radar platform. The cataract progressed rapidly and this was documented by anterior segment photos. The primary damage mechanism of microwave radiation is thermal, by dielectric heating. Non-thermal effects are less understood. Cataract formation after microwave exposure has been proven in experimental animal eyes and reported in isolate not well documented cases. The timeframe of cataract onset after exposure to the radar high microwave energy and the very unusual rapid progression of this cataract raise the odds of a causative relationship.
"Several studies with appropriate methodologies reflect the capacity of electromagnetic radiations to cause adverse health effects and there are several credible mechanisms that can account for the observed effects. Hence, need of the hour is to activate comprehensive well-coordinated blind scientific investigations, overcoming all limitations and demerits of previous investigations especially replication studies to concretize the earlier findings. Furthermore, appropriate exposure assessment is crucial for identification of dose-response relation if any, and the elucidation of biological interaction mechanism. For the time being, the public should follow the precautionary principle and limit their exposure as much as possible."
"There are poor oxidative toxic effects of one hour of Wi-Fi exposure on the lens in the animals. However, melatonin supplementation in the lens seems to have protective effects on the oxidant system by modulation of GSH-Px activity."
"We examined and monitored a dairy farm in which a large number of calves were born with nuclear cataracts after a mobile phone base station had been erected in the vicinity of the barn. Calves showed a 3.5 times higher risk for heavy cataract if born there compared to Swiss average. All usual causes such as infection or poisoning, common in Switzerland, could be excluded. The real cause of the increased incidence of cataracts remains unknown."
"Because of the increased use of modern radiofrequency devices, public concern about the possible health effects of exposure to microwave radiation has arisen in many countries. It is well established that high-power microwave radiation can induce cataracts via its thermal effects. It remains unclear whether low-power microwave radiation, especially at levels below the current exposure limits, is cataractogenic. This review summarizes studies on the biological effects of low-power microwave radiation on lens and lens epithelial cells (LECs). It has been reported that exposure affects lens transparency, alters cell proliferation and apoptosis, inhibits gap junctional intercellular communication, and induces genetic instability and stress responses in LECs. These results raise the question of whether the ambient microwave environment can induce non-thermal effects in the lens and whether such effects have potential health consequences. Further in vivo studies on the effects on the lens of exposure to low-power microwave radiation are needed."
"The results of this study suggest that computer-monitor radiation leads to oxidative stress in the corneal and lens tissues, and that vitamin C may prevent oxidative effects in the lens."
"Our results suggest that exposure to RF of wireless communications can induce expression of Hsp27 and Hsp70 and the activation of ERK1/2 and JNK1/2 in human LECs. The induction of Hsp27 and Hsp70, by a non-thermal stress, together with the activation of signal transduction pathways, provides reliable and sensitive biomarkers that could serve as the basis for improved mobile phone safety guidelines."
"Microwave radiation induced hLEC DNA damage after G(0)/G(1) arrest does not lead to cell apoptosis. The increased ROS observed may be associated with DNA damage. Superposed electromagnetic noise blocks microwave radiation-induced DNA damage, ROS formation, and cell cycle arrest."
"DNA damage induced by 1.8 GHz radiofrequency field for 2 h, which was mainly SSBs, may be associated with the increased ROS production. Electromagnetic noise could block RF-induced ROS formation and DNA damage."
"Exposure to 1.1 GHz, 2.22 mW microwaves caused a reversible decrease in lens optical quality accompanied by irreversible morphological and biochemical damage to the lens epithelial cell layer. The effect of the electromagnetic radiation on the lens epithelium was remarkably different from those of conductive heat. The results of this investigation showed that electromagnetic fields from microwave radiation have a negative impact on the eye lens. The lens damage by electromagnetic fields was distinctly different from that caused by conductive heat."
"Two-dimensional polyacrylamide gel electrophoresis combined with mass spectrometry may be a powerful tool for screening potential electromagnetic-reaction protein markers. HSP70 and hnRNP K are involved in the stress reaction of HLECs exposed to microwaves. These cell responses are nonthermal effects of the electromagnetic field."
"Microwave radiation higher than 1.00 mW/cm(2) can affect the proportion of WSP and USP in cultured rabbit lens, and cause changes of lens transparency and refractive power, which leads to lens opacity."
"The results of this study suggest that mobile telephone radiation leads to oxidative stress in corneal and lens tissues and that antioxidants such as vitamin C can help to prevent these effects."
"No or repairable DNA damage was observed after 2 hour irradiation of 1.8 GHz microwave on LECs when SAR < or = 3 W/kg. The DNA damages caused by 4 W/kg irradiation were irreversible."
"A novel experimental system was used to investigate the localized effects of microwave radiation on bovine eye lenses in culture for over 2 weeks. Using this setup, we found clear evidence that this radiation has a significant impact on the eye lens. At the macroscopic level, it is demonstrated that exposure to a few mW at 1 GHz for over 36 h affects the optical function of the lens. Most importantly, self-recovery occurs if the exposure is interrupted. At the microscopic level, close examination of the lens indicates that the interaction mechanism is completely different from the mechanism-causing cataract via temperature increase. Contrary to the latter's effect, that is particularly pronounced in the vicinity of the sutures and it is assumed to be a result of local friction between the edges of the fibers consisting the lens. Even if macroscopically the lens has recovered from the irradiation, microscopically the indicators of radiation impact remain."
"It is concluded that the use of mobile phone is a health risk factor, and thus it is suggested that excessive use of mobile phones should be avoided and social awareness increased through health promotion activities, such as group discussions or public presentations and via electronic and printed media sources."
"This study suggests that low power microwave radiation higher than 0.50 mW/cm2 can inhibit lens epithelial cell proliferation, and increase the expression of P27Kip1. These effects may account for the decline of lens epithelial proliferation after exposure to microwave radiation."
"Low power densities microwave radiation (5 mW/cm(2) and 10 mW/cm(2)) induces damage to connexin 43 and inhibits the GJIC of rabbits LECs. These changes result in an osmotic imbalance within the lens and induce early cataract. 5 mW/cm(2) or 10 mW/cm(2) microwave radiation is cataractogenic."
"Low power densities of microwave radiation (5 mW/cm2 and 10 mW/cm2) can induce irreversible damage to rabbit lens epithelial cells. This may be the non-thermal effect of microwave radiation."
"The low power level microwave (10 mW/cm(2)) can induce the ultrastructural changes of rabbit lens epithelial cells, this may be the appearance of early irreversible microwave radiation injury. In regard to the pathogenic mechanism, it is necessary to perform further investigations."
"Microwaves most commonly cause anterior and/or posterior subcapsular lenticular opacities in experimental animals and, as shown in epidemiologic studies and case reports, in human subjects. The formation of cataracts seems to be related directly to the power of the microwave and the duration of exposure. Until further definitive conclusions about the mechanism of microwaves and ionizing cataracts are reached, and alternative protective measures are found, one can only recommend mechanical shielding from these radiations to minimize the possibility of development of radiation-induced cataracts."
"Differences were found between the control group and the groups of animals exposed to microwaves in which the glutathione concentration in the cortex and core of the lens was decreasing with time in proportion to the number of exposures. Parallelly to the number of days of exposure to microwaves the enzymatic activity of carboxypeptidase A and aminopeptidase increased in the cortex of the lens. The observed changes demonstrate cumulation of the absorbed microwave energy leading to changes in the permeability of the capsule and membranes of lenticular fibres which lead to secondary metabolic disturbances in the lens of the eye."
"A parametric study of heat and pulsed microwave energy was performed on murine ocular lens in vitro. Adult rat lenses were placed in a specially designed chamber with thermostat in which temperature was maintained by the circulation of thermostatically regulated phosphate-buffered saline, during irradiation with 915 MHz microwaves. Irradiation in pulsed (Pu) mode was used. Lenses exposed at 37°C to pulsed irradiation at specific absorption rates (SAR) equal to or greater than 400 mW/g, and immediately fixed, showed numerous small holes (not previously reported for other in vitro cataracts) in the equatorial cell surfaces, when examined by scanning electron microscopy (SEM). At 39°C with SAR equal to or greater than 120 mW/g similar holes appeared. On continued incubation for two days the holes could not be seen as easily because globular degeneration appeared to advance into the equatorial areas where holes had originally been seen. In lenses exposed to 120 mW/g at 37°C globular degeneration and equatorial subcapsular foam were observed. At SAR values equal to or above 400 mW/g at 39°C and 1·2 W/g at 37°C, large globules characteristic of temperature elevation to 47 or 50°C were observed, indicating that the effect of the electromagnetic field itself in the absence of any comparable temperature elevation, was equivalent to a 10°C rise in temperature. An unexpected finding was the apparent fragmentational stretching of the capsule observed by SEM, in lenses fixed immediately after irradiation at 37°C at an SAR value of 1·2 W/g. These effects: holes, foam, large globules and capsular damage are apparent examples of physical damage to the lens. Modern radars using directional antennas can deliver pulse power densities many times higher than those employed in these experiments. This work indicates that additional effects of microwave irradiation dependent on modulation should also be considered as potential hazards in setting safety standards."
"In 1948 two groups of investigators reported independently and almost coincidentally that when the eyes of rabbits or dogs were exposed to sufficient microwave radiation, opacities subsequently developed in the crystalline lens. Both groups employed continuous wave radiation at a frequency of 2.45 GHz. with a wave length of 12.3 cm. In the 30 years since that initial discovery, this phenomenon has been extensively investigated in numerous laboratories and we now have a substantial body of information concerning it. However, we have yet to identify the site and the manner of interaction between microwaves and ocular tissues which provide the mechanism for cataractogenesis."
"The widespread availability of radiant energy sources such as diathermy machines, microwave ovens, and electric ovens and ranges makes it imperative to examine carefully any possible hazards that may result from their use. With this in mind, radiant energy should be considered in the differential diagnosis of cataractogenesis."
"The absorbed power distribtuion pattern in the eyes of rabbits exposed to near-zone 2450-MHz radiation has been derived from thermocouple measurements. The results indicated that the absorption increased steadily until a peak of 0.92 W/kgm for each millwatt/square centimeter incident was reached in the vitreous body (just behind the lens) and then fell off rapidly as the depth increased, thereby suggesting the lens may be the most susceptible or critical part of the eye to near-zone 2450-MHz radiation. This contention was strongly supported by our time and power-density threshold studies. Following irradiation, irreversible changes in the lens were seen in the posterior cortical area only. All other changes in the eye were transient and disappeared by the second postirradiation day."
"Rabbits were irradiated with 2450-MHz continuous microwave energy. Effects of the radiation on the ocular lens were assessed by slit-lamp biomicroscopic examination of the eye. Two lenses were selected for electron microscopy, one that was severely damaged and one that appeared unaffected by the radiation. There were prominent ultrastructural changes in both lenses."
"The growing body of Russian and eastern European literature describing a wide variety of functional changes and clinical effects, leading to consideration of "radio-wave sickness" as a possible independent nosologic entity, cannot simply be ignored. With increasing uses and power, the stage is set for the appearance of late effects previously undetected possibly because of their infrequency, lack of distinctiveness or mild character. There may now be a better opportunity to resolve the uncertainties of present knowledge in the face of an increasing risk."
"The development of cataract as a result of electromagnetic radiations is well established. Formerly it was supposed that this effect was unique to the action of infra-red, ultraviolet and roentgen radiations, although as early as 1926 in a survey of work in these fields Duke-Elder1 suggested that other portions of the spectrum, if of sufficient magnitude, might produce cataract. On the other hand, as late as 1944 it was the opinion of Bellows, basing his views on the work of Legge and of Hartridge and Hill, that electromagnetic waves longer than 20,000 angstrom units would be absorbed completely by the cornea. In 1948 it was demonstrated by Richardson, Duane and Hines5 that lenticular opacities could be produced by continuous microwave radiations of 12.25 cm. wavelength. These observations were confirmed by the contemporary work of Daily, Wakim, Herrick and Parkhill, which was completed later in 1948. The following year Salisbury, Clark and Hines in a technical article attributed the damage to a ready transmission through the cornea and a high absorption by the lens of microwaves 10 to 12 cm in wavelength."