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The significance of microwaves in the environment and its effect on plants
Abstract
Wireless technologies are becoming popular due to convenient lower implementation costs and operational costs compared with wired technologies. Various wireless internet and communication technologies, such as worldwide interoperability for microwave access (WiMAX) and long-term evolution (LTE), are expanding rapidly. As with mobile phones, all of these technologies operate using high-frequency electromagnetic waves in the microwave category (3 × 102 – 3 × 106 MHz). An increasing number of operators within a geographical area is resulting in high microwave densities in the environment. At the same time, wireless technologies are now utilizing radio frequency electromagnetic radiation of up to 5500 MHz, and frequency spectrum allocation tables indicate that countries have allocated additional high frequencies for broadcasting purposes. Scientists have widely investigated the effects of microwaves on humans and animals, and some findings confirm that such effects exist. In comparison, a very limited number of published studies have addressed the effects of microwaves on plants. The findings of these studies indicate that the effects of microwaves on plants depend on the plant family and growth stage involved as well as the exposure duration, frequency, and power density, among other factors. However, the number of published studies is not yet sufficient to support drawing strong conclusions regarding the effects of microwaves on whole plant communities. Therefore, further studies are necessary to support present findings and uncover new findings.
... Numerous studies have focused on the effects of microwaves on human health which have confirmed that exposure guidelines, which are solely based on thermal effect, are no longer providing reliable protection to humans (Senavirathna and Asaeda 2014). On the other hand, plants, which are currently not considered for protection against microwaves, are vulnerable to the consequences of exposure. ...
... The present experiment proved the existence of exposure effects on seedlings, as some of the measured parameters were altered compared to those in control. However, although previous studies have reported stress or negative impacts (Senavirathna and Asaeda 2014), the present findings showed a somewhat stimulatory effect of microwaves on Arabidopsis seedlings, though the H 2 O 2 level was increased compared to that of the control. ...
... Microwave properties, frequency, power density, polarization and exposure duration are determining factors of plant responses (Tkalec et al. 2007;Senavirathna and Asaeda 2017). On the other hand, the growth stage and plant species are confirmed determining factors of the plant response to microwaves (Senavirathna and Asaeda 2014). Therefore, the response of plants to microwaves is complicated and must be discussed related to the plant characteristics as well as the microwave properties. ...
Communication technologies are moving toward higher microwave frequencies and bandwidths to satisfy the growing demand for high data rates. The concern about the possible effects of microwaves on plants and animals has increased recently. There is still uncertainty concerning the effects of microwaves on plants. The present study was conducted to investigate the effect of industrial, scientific and medical (ISM) radio band microwaves on seedlings and seeds of Arabidopsis thaliana (L.). In vitro growing A. thaliana wild-type seedlings and seeds were exposed to 2.45 GHz continuous-wave microwaves at a power flux density of 1.0 ± 0.1 W m−2 for 48 h. Microwave exposure increased the hydrogen peroxide content, photosynthetic pigments, nonphotochemical quenching and fluorescence of the seedlings, while peroxidase activity and Fv/Fm values were unchanged. Anthocyanin and malondialdehyde were decreased. Seed germination rate, fresh weight and photosynthetic pigment contents of 10-day-old seedlings obtained from microwaves exposed seeds remained unchanged. Results confirmed the inexistence of oxidative stress but a stimulatory effect of microwave on A. thaliana seedlings. The increased hydrogen peroxide content and nonphotochemical quenching suggest acceptance of extra photon energy and a portion of the excess captured photon passing through the photosystem, while a portion of energy dissipated as heat.
... A few studies investigated effects of RF-EMF radiation on plants. In recent decades, a few researchers have reviewed RF-EMF effects on plants (Belyavskaya, 2004;Cucurachi et al., 2016;Panagopoulos et al., 2016;Senavirathna and Takashi, 2014;Vian et al., 2016) and observed the potential trend of RF-EMF influence on plants. On the other hand, phenotypic plasticity of plants will allow them to change their structure and function; hence, plants adapt to environmental changes (Nicotra et al., 2010). ...
... Our analysis from the reported studies demonstrated the potential impact of weak radiofrequency exposure from mobile phone radiation on plants. This observation was also supported by other studies (Cucurachi et al., 2016;Panagopoulos et al., 2016;Senavirathna and Takashi, 2014); however, in contrast, Verschaeve (2014) study was not supported. Irrespective to this, Panagopoulos et al. (2016) criticized Verschaeve (2014) review study about his analysis. ...
... Investigations in the field of effects of the weak RF-EMFs and radiation have focused on animals (Eberhardt et al., 2008;Finnie et al., 2009;Gannes et al., 2009;Hirota et al., 2009;Masuda et al., 2009;Nittby et al., 2011;Tang et al., 2015), plants (Gremiaux et al., 2016;Gustavino et al., 2016;Halgamuge et al., 2015;Kumar et al., 2015;Senavirathna et al., 2014a, b), epidemiological evidence (Benson et al., 2013;Hardell et al., 2005Hardell et al., , 2009Johansen et al., 2001;Linet et al., 2006;Schüz et al., 2006), children (Elliott et al., 2010;Li et al., 2012;Sudan et al., 2013a, b), human sleep research (Arnetz et al., 2007;Danker-Hopfe et al., 2010, 2015Leitgeb et al., 2008;Loughran et al., 2012;Lowden et al., 2011;Regel et al., 2007) and cell cultures (Hook et al., 2004;Kazemi et al., 2015;Kim et al., 2015;Koyama et al., 2015;Liu et al., 2015). Many types of research used 900 MHz (Cucurachi et al., 2016;Senavirathna and Takashi, 2014) as 900 MHz frequencies are utilized in GSM technology. EMR frequencies between 2000 and 6000 MHz are being tested due to the expansion of UMTS technology for mobile phone communication (Senavirathna and Takashi, 2014). ...
Aim:
The aim of this article was to explore the hypothesis that non-thermal, weak, radiofrequency electromagnetic fields (RF-EMF) have an effect on living plants.
Subject and methods:
In this study, we performed an analysis of the data extracted from the 45 peer-reviewed scientific publications (1996-2016) describing 169 experimental observations to detect the physiological and morphological changes in plants due to the non-thermal RF-EMF effects from mobile phone radiation. Twenty-nine different species of plants were considered in this work.
Results:
Our analysis demonstrates that the data from a substantial amount of the studies on RF-EMFs from mobile phones show physiological and/or morphological effects (89.9%, p < 0.001). Additionally, our analysis of the results from these reported studies demonstrates that the maize, roselle, pea, fenugreek, duckweeds, tomato, onions and mungbean plants seem to be very sensitive to RF-EMFs. Our findings also suggest that plants seem to be more responsive to certain frequencies, especially the frequencies between (i) 800 and 1500 MHz (p < 0.0001), (ii) 1500 and 2400 MHz (p < 0.0001) and (iii) 3500 and 8000 MHz (p = 0.0161).
Conclusion:
The available literature on the effect of RF-EMFs on plants to date observed the significant trend of radiofrequency radiation influence on plants. Hence, this study provides new evidence supporting our hypothesis. Nonetheless, this endorses the need for more experiments to observe the effects of RF-EMFs, especially for the longer exposure durations, using the whole organisms. The above observation agrees with our earlier study, in that it supported that it is not a well-grounded method to characterize biological effects without considering the exposure duration. Nevertheless, none of these findings can be directly associated with human; however, on the other hand, this cannot be excluded, as it can impact the human welfare and health, either directly or indirectly, due to their complexity and varied effects (calcium metabolism, stress proteins, etc.). This study should be useful as a reference for researchers conducting epidemiological studies and the long-term experiments, using whole organisms, to observe the effects of RF-EMFs.
... Многие ученые исследовали эффекты, возникающие при действии СВЧ-излучения на растения и их семена [46]. Большинство из имеющихся исследований описывают результаты воздействия СВЧ-излучения частотой 2,45 ГГц, которое поглощается молекулами воды в живых клетках, вызывая их нагрев [47]. ...
... Однозначно доказанной можно считать эффективность предпосевной обработки семян СВЧ-излучением для их обеззараживания, заключающегося в уничтожении патогенных микроорганизмов и насекомых-вредителей [5,6,46]. ...
Исследование проводили с целью обобщения и анализа научных публикаций, посвященных физическим методам стимулирования прорастания семян и уточнению информации о способах их реализации. Для обзора использовали источники по теме исследования за 2012–2022 гг. Научные статьи, опубликованные ранее 2012 г., включали в случае отсутствия новых публикаций по конкретному аспекту темы исследования. Для предпосевной обработки семян используют такие физические методы воздействия, как магнитное поле, микроволновое излучение, ультрафиолетовое излучение, «холодная» плазма, ионизирующие излучения, ультразвук, импульсное электрическое поле. Их считают экологически безопасными и безвредными для здоровья людей и животных. Рассмотренные физические методы предпосевной обработки улучшают всхожесть семян до 30 % и скорость роста до 20 %. Их использование в перспективе позволит создать производительные поточные линии для подготовки большого количества семян. Наиболее простыми и подходящими для практического применения в сельском хозяйстве из рассмотренных методов следует считать воздействие ультразвука и ультрафиолетового излучения. Остальные методы в существующем виде достаточно сложны и энергозатратны для непосредственного использования при обработке большого количества семян. Активному распространению рассмотренных методов препятствует недостаточный уровень знаний о биохимических и физических процессах, происходящих в семенах в результате их обработки. Для решения этой проблемы необходим комплексный и междисциплинарный подход, что позволит углубить и ускорить фундаментальные исследования, а также выработать практические рекомендации для сельскохозяйственного производства.
The study aimed to summarise and analyse scientific publications devoted to physical methods for stimulating seed germination and to clarify information on how to implement them. For the review, we used sources on the research topic for 2012–2022. Scientific articles published before 2012 were included in the absence of new publications on a specific aspect of the research topic. For preplanting cultivation of seeds, such physical methods of influence as a magnetic field, microwave radiation, ultraviolet radiation, "cold" plasma, ionizing radiation, ultrasound, pulsed electric field are used. They are considered environmentally friendly and harmless to human and animal health. The considered physical methods of presowing treatment improve seed germination up to 30% and growth rate up to 20%. Their use in the future will make it possible to create productive flow lines for the preparation of a large number of seeds. Among the considered methods, the most simple and suitable for practical application in agriculture should be considered ultrasound exposure and ultraviolet radiation. The remaining methods in their current form are quite complex and energy-consuming for direct use in the processing of a large number of seeds. The active spread of the considered methods is hindered by the insufficient level of knowledge about the biochemical and physical processes that occur in seeds as a result of their processing. To solve this problem, an integrated and interdisciplinary approach is needed, which will allow deepening and accelerating fundamental research, as well as developing practical recommendations for agricultural production.
... MWs can induce various biological changes depending on different factors such as field strength, frequencies, waveforms, modulation, and duration of exposures (Vian et al., 2006). Mostly the effect of MWs on humans and animals was extensively studied and addressed, while there is a very small number of studies related to the effect of MWs on plants (Jayasanka and Asaeda, 2013). Most of the available work described the effect of radiations having the 2.45 GHz frequency, which is absorbed in living cells through water molecules (Creţescu et al., 2013). ...
... The results exhibited that WLAN frequency MWs appeared to be more harmful than GSM-frequency MWs, and the MWs treatments caused both structural and chemical alternations (Soran et al., 2014). Like other radiation treatments, the efficiency of MWs application depends on different parameters such as plant species, growth stage, exposure duration, frequency, and power density (Jayasanka and Asaeda, 2013). Different studies in this area revealed that MWs treatment showed a positive effect on some plants while negatively influencing other plants; which recommended that the influence of MWs is related to radiation frequency, exposure duration, and environmental circumstances (Khalafallah and Sallam, 2009). ...
For nutritional security, the availability of nutrients from food sources is a crucial factor. Global consumption of edible seeds including cereals, pulses, and legumes makes it a valuable source of nutrients particularly vitamins, minerals, and fiber. The presence of anti-nutritional factors forms complexes with nutrients, this complexity of the nutritional profile and the presence of anti-nutritional factors in edible seeds lead to reduced bioavailability of nutrients. By overcoming these issues, the germination process may help improve the nutrient profile and make them more bioavailable. Physical, physiological, and biological methods of seed invigoration can be used to reduce germination restraints, promote germination, enhance early crop development, to increase yields and nutrient levels through sprouting. During sprouting early start of metabolic activities through hydrolytic enzymes and resource mobilization causes a reduction in emergence time which leads to a better nutritional profile. The use of physical stimulating methods to increase the sprouting rate gives several advantages compared to conventional chemical-based methods. The advantages of physical seed treatments include environment-friendly, high germination rate, early seedling emergence, uniform seedling vigor, protection from chemical hazards, and improved yield. Different physical methods are available for seed invigoration viz. gamma irradiation, laser irradiation, microwaves, magnetic field, plasma, sound waves, and ultrasonic waves. Still, further research is needed to apply each technique to different seeds to identify the best physical method and factors for seed species along with different environmental parameters. The present review will describe the use and effects of physical processing techniques for seed invigoration.
... Additionally, MWs treatment has emerged as a worthy non-chemical alternative for weed control in greenhouses from horticultural and ornamental plant nurseries. But the impacts of MWs on seeds depend on plant species or genotypes, exposure duration, frequency of waves and power density (Jayasanka and Asaeda 2014). However, such a promising approach to weed control through MWs treatments should depend on the design of novel chemical-free approaches in agro-industry and disease control in seed storage and seed production systems. ...
... Even though many researchers are involved in investigating the priming effect of microwave in different crop species, it is quite limited as compared to a huge investigation on the effects of MWs on humans and animals which are being carried out globally (Jayasanka and Asaeda 2014). Nonetheless, the exact mechanisms or biochemical processes by which microwaves can affect the functioning of living organisms are not very well understood to date. ...
Seed priming has long been explored as an effective value-added potential technique that results in improved germination, reduced seedling emergence time, shortened crop duration, increased stress tolerance and eventually increased higher grain production. However, the wider applicability of water or chemical-based conventional methods of seed priming is often restricted considering its deleterious effects on post-treatment storability or agricultural pollution due to the persistence of chemicals in plant systems or in the environment. In this context, the utilization of physical methods of seed priming for enhancing plant productivity has created a new horizon in the domain of seed technology. Being eco-friendly and cost-effective approaches, priming with extra-terrestrial or physical agents such as ionizing radiation such as X-rays and gamma rays and non-ionizing radiation such as ultrasonic wave, magnetic field, microwaves, and infrared light offers many advantages along with ensuring enhanced production over conventional methods. Ultraviolet radiations, bridging between ionizing and non-ionizing radiation, are important electromagnetic waves that would also be an effective priming agent. Non-ionizing radiation has certain biological advantages over ionizing radiation since it does not generate charged ions while passing through a subject, but has enough energy to cause biological effects. Extensive research works to study the effects of various non-ionizing physical priming methods are required before their wider exploitation in agriculture. With this background, this review aims to highlight the current understanding of non-ionizing physical methods of seed priming and its applicability to combat present-day challenges to achieve agro-ecological resilience.
... Numerous studies have shown the effect of EMR on plants; clearly, both the electric and magnetic fields of the EMR affect plants. 11,12 However, due to the dielectric activity enforced on charged ions and dipolar molecules, the effects of the electric field can be intense. The dielectric activity causes charged ions and dipolar molecules to align along the direction of the electric field and to vibrate proportionately to the oscillation frequency (the wave frequency) of the electric field. ...
... 13,30 However, such research must be carefully conducted, as microwave exposure-induced wounding and stress-related gene expression and accumulation of stress-related substances have been reported in most studies. 11 Moreover, microwave frequency, power density, polarization and duration of exposure are factors which are known to determine the nature and the magnitude of the effects form microwave radiation. On the other hand, plantrelated factors, such as species, growth stage, age and physical conditions are also very important. ...
The dielectric effect enforced on charged ions and dipolar molecules by the oscillating electric field of microwaves may influence electric signaling in plants. In the present study, the exposure of Nicotiana benthamiana plants to continuous wave 2.45 GHz microwave radiation with 1.9 – 2.1 W m⁻² power density significantly reduced the amplitude of leaf burning-induced variation potential along the plant stem. The change in amplitude of the variation potential occurred mainly because of a significant reduction of the depolarization rate. This effect was not observed during the post-microwave exposure period. The unique characteristics observed in the variation potentials were also observed under microwave exposure, suggesting unaffected information delivery to distant locations or unaffected transport of specific chemicals generated by the injury.
... In a review of the effects of environmental microwaves on plants (Jayasanka and Asaeda, 2013), it was indicated that effects depend on the plant family and the growth stage, as well as the exposure duration, frequency, and power density. This review concluded that most studies that address the effects of microwaves on animals and plants have documented effects and responses at exposures below limits specified in the electromagnetic radiation exposure guidelines and it is therefore necessary to rethink these guidelines (Jayasanka and Asaeda, 2013). ...
... In a review of the effects of environmental microwaves on plants (Jayasanka and Asaeda, 2013), it was indicated that effects depend on the plant family and the growth stage, as well as the exposure duration, frequency, and power density. This review concluded that most studies that address the effects of microwaves on animals and plants have documented effects and responses at exposures below limits specified in the electromagnetic radiation exposure guidelines and it is therefore necessary to rethink these guidelines (Jayasanka and Asaeda, 2013). ...
In the last two decades, the deployment of phone masts around the world has taken place and, for many years, there has been a discussion in the scientific community about the possible environmental impact from mobile phone base stations. Trees have several advantages over animals as experimental subjects and the aim of this study was to verify whether there is a connection between unusual (generally unilateral) tree damage and radiofrequency exposure. To achieve this, a detailed long-term (2006-2015) field monitoring study was performed in the cities of Bamberg and Hallstadt (Germany). During monitoring, observations and photographic recordings of unusual or unexplainable tree damage were taken, alongside the measurement of electromagnetic radiation. In 2015 measurements of RF-EMF (Radiofrequency Electromagnetic Fields) were carried out. A polygon spanning both cities was chosen as the study site, where 144 measurements of the radiofrequency of electromagnetic fields were taken at a height of 1.5m in streets and parks at different locations. By interpolation of the 144 measurement points, we were able to compile an electromagnetic map of the power flux density in Bamberg and Hallstadt. We selected 60 damaged trees, in addition to 30 randomly selected trees and 30 trees in low radiation areas (n=120) in this polygon. The measurements of all trees revealed significant differences between the damaged side facing a phone mast and the opposite side, as well as differences between the exposed side of damaged trees and all other groups of trees in both sides. Thus, we found that side differences in measured values of power flux density corresponded to side differences in damage. The 30 selected trees in low radiation areas (no visual contact to any phone mast and power flux density under 50μW/m(2)) showed no damage. Statistical analysis demonstrated that electromagnetic radiation from mobile phone masts is harmful for trees. These results are consistent with the fact that damage afflicted on trees by mobile phone towers usually start on one side, extending to the whole tree over time.
Paper in:
http://media.withtank.com/592b5448ab/waldmann-selsam_2016_scitotenv572p554-569_rf__trees.pdf
http://kompetenzinitiative.net/KIT/KIT/baeume-in-bamberg/
http://kompetenzinitiative.net/KIT/wp-content/uploads/2016/09/Trees-in-Bamberg-and-Hallstadt-Documentation-2006-2016.pdf
https://groups.google.com/forum/#!topic/mobilfunk_newsletter/5r37cJ-EqPI
... 2006). While the effects of MWs on humans and animals were widely investigated, a very limited number of published studies have addressed the MWs-mediated effects on plants (Jayasanka and Asaeda, 2014). Interestingly, most of the studies currently available describe the impact of the 2.45 GHz radiation, which is absorbed by water molecules in living cells (Iuliana et al., 2013). ...
... While the 2.45 GHz MWs radiation has no clear effect in seed germination, it seems to be beneficial on seedling growth and biomass accumulation in different species (Aladjadjiyan, 2010;Jakubowski, 2010;Talei et al., 2013). As described for other types of radiation treatments, the effects of MWs on seeds depend on the plant species and growth stage, as well as, exposure duration, frequency, power density (Jayasanka and Asaeda, 2014). The number of studies available is still not sufficient to evaluate the impact of MWs in plant systems, neither in seed technology. ...
In the context of seed technology, the use of physical methods for increasing plant production offers advantages over conventional treatments based on chemical substances. The effects of physical vigourization treatments in seeds can be now addressed at multiple levels, ranging from morpho-structural aspects to changes in gene expression and protein or metabolite accumulation. Among the physical methods available, ”magneto-priming” and irradiation with microwaves or ionizing radiations are the most promissory pre-sowing seed treatments. ”Magneto-priming” is based on the application of magnetic fields and described as an eco-friendly, cheap, non-invasive technique with proved beneficial effects on seed germination, vigour and crop yield. Ionizing radiations, as gamma-rays and X-rays, have been widely regarded as a powerful tool in agricultural sciences and food technology. Gamma-rays delivered at low dose have showed to enhance germination percentage and seedling establishment, acting as an actual ‘priming’ treatment. Different biological effects have been observed in seeds subjected to microwaves and X-rays but knowledge about their impact as seed vigourization agent or stimulatory effects on germination need to be further extended. Ultraviolet (UV) radiations, namely UV-A and UV-C have shown to stimulate positive impacts on seed health, germination and seedling vigour. For all mentioned physical treatments, extensive fundamental and applied research is still needed to define the optimal dose, exposition time, genotype- and environment-dependent irradiation conditions. Electron paramagnetic resonance (EPR) has an enormous potential in seed technology not fully explored to monitor seed vigourization treatments and/or identifying the best suitable irradiation dose or time-point to stop the treatment. The present manuscript describes the use of physical methods for seed vigourization, while providing a critical discussion on the constraints and advantages. The future perspectives related to the use of these approaches to address the need of seed technologists, producers and trade markers will be also highlighted.
... A very limited number of studies have addressed the effects of electromagnetic radiation on plants. The findings of these studies indicate that the effects depend on the plant family, growth stage involved and the radiation characteristics, among other factors (Jayasanka and Asaeda, 2013). High-frequency electromagnetic fields alter the chlorophyll in black locust (Robinia pseudoacacia) seedlings and in duckweeds (Lemna minor) exposed (Sandu et al., 2005;Jayasanka et al., 2013). ...
... The findings of these studies indicate that the effects depend on the plant family, growth stage involved and the radiation characteristics, among other factors (Jayasanka and Asaeda, 2013). High-frequency electromagnetic fields alter the chlorophyll in black locust (Robinia pseudoacacia) seedlings and in duckweeds (Lemna minor) exposed (Sandu et al., 2005;Jayasanka et al., 2013). In tomato plants (Lycopersicon esculentum), which were exposed to low-level (5 V/m) electromagnetic fields for a short period (10 min), changes were found in the abundance of three specific mRNAs after exposure, strongly suggesting that they were the direct consequence of application of radio-frequency fields (Roux et al., 2007). ...
Despite the widespread use of wireless telephone networks around the world, authorities and researchers have
paid little attention to the potential harmful effects of mobile phone radiation on wildlife. This paper briefly
reviews the available scientific information on this topic and recommends further studies and specific lines of
research to confirm or refute the experimental results to date. Controls must be introduced and technology
rendered safe for the environment, particularly, threatened species.
... That is why the emerging gradients of heat, moisture, and pressure, directed from the inside to the material layer surface, increase the drying efficiency. However, the influence of such physical processes on plants' vital properties has not yet been investigated [6]. Electromagnetic radiation influence on the plants affects all the layers of the living organisms' organization, starting from the gene expression, controlling the metabolism, and ending with the morphological and structural changes [7]. ...
Stricter requirements to environmental compatibility and smaller energy-output ratio highlight the importance of implementing the super high-frequency drying of the crop seeds. The study is aimed at the development of drying optimal parameters and modes of sunflower (Helianthus annuus L.) seeds in a settled small-size conveyor microwave unit. In-gel activity of 6 functionally key enzymes (formate dehydrogenase, glutamate dehydrogenase, malate dehydrogenase, diaphorase, leucine aminopeptidase and non-specific esterases) in polyacrylamide gels after disk electrophoresis was analyzed in order to count on an additional assessment of the temperature influence caused by electromagnetic radiation of the tested drying unit on the sunflower achenes metabolism. The correlation analysis showed the existence of the statistically significant (р < 0.05) negative dependence between the seed materials heating temperature with germination energy (correlation coefficient -0.783) and achenes germination (-0.797). These two parameters (without processing 88 and 96%, respectively) began to reduce sharply when reaching the heating temperatures of 55℃ and more. Enzymes de-activation also started within this range. Considering the collected data about drying of the seed material, the optimal heating conditions were within 26-27 minutes at 800 W and heating temperature 38-40° С. With these parameters the quality of the processed seeds was preserved, and the costs for drying were relatively low (2.61 MJ per 1 kg of the water removed).
... В цьому напрямку методи термообробки з використанням енергії мікрохвильового електромагнітного поля давно зарекомендували себе як високоефективні [1]. Застосування мікрохвильового нагрівання визнано доцільним для модернізації ряду технологічних схем виробництв [2][3][4][5][6][7]. Однак неповнота знань про ефекти впливу мікрохвильового поля на рослинні матеріали не дозволяє переходити на ефективні мікрохвильові технології. ...
The article reviews various techniques for mathematical modeling of the soybean drying process. The purpose of this paper is to review, analyze and compare existing approaches to mathematically describe the processes of moisture movement during microwave drying of soybeans. The only way to provide mathematical modeling of the processes occurring in the soybean grain is a combination of the transformation of microwave energy into heat, the heating of dipole water molecules existing in the seed, the processes of moving moisture from the center to the grain shell and evaporation of moisture. Today, microwave drying is one of the promising areas for research, because this method is much more efficient than traditional post-harvest grain drying methods and, at the same time, poorly understood. Factors on which the process of microwave drying depends on are the speed of movement of moisture in the micropores of the product, the initial temperature and humidity of the raw material, the placement of the main magnetron relative to the object of drying and the speed of movement of raw materials in the drying chamber. The object of the study in this article was to simplify the mathematical model of soybean seeds. To intensify the process of microwave drying, it is advisable to use a combined effect, such as blowing, which increases the intensity and quality of the process of microwave dehumidification. In addition, in this case, the simultaneous use of two or more factors of influence, which allows for rapid processing of raw materials. This determines the relevance and prospects of this study. The developed criteria criterion is substantiated and described, which allows to simplify the complex calculation of microwave energy transfer processes, sample heating and moisture velocity in it. The basic approaches to the construction of a mathematical model of the soybean drying process are considered, and their expediency is determined. The analysis of various methods of mathematical description of the drying process is carried out, the main disadvantages of these methods are identified. It is established that drying soybean seeds in the microwave field is one of the most promising. A mathematical model for a combined soybean drying process with a combination of microwave drying methods and air blowing is proposed.
... From 1974 to 2017 over 80 original peer-reviewed studies were published on this topic, and ca. 90% of them showed significant effects on plants such as the inhibition, or more rarely, stimulation of growth, changes in various metabolic activities and alteration of gene expression (Cucurachi et al., 2013;Senavirathna and Asaeda, 2014;Vian et al., 2016;Halgamuge 2017). In some of these studies (Pesnya and Romanovsky 2013;Halgamuge et al., 2015;Waldmann-Selsam et al., 2016) the exposure did not exceed the levels that occur in the vicinity of mobile phone base stations (Mann et al., 2000;Urbinello et al., 2014;Chief Inspectorate of Environmental Protection of Poland, 2018). ...
... There are limited studies with a few plants regarding the impact of microwaves' treatment on germination and yield performance. As observed for different ways of irradiation, the impacts of MWs AU:7 on seeds are determined by the particular plant species, their growth stage, along with the time of treatment, numbers of treatment, and dose (Jayasanka and Asaeda, 2013). The experiments existing so far are inappropriate to determine the effects of MWs either in plants or in seed industries. ...
Agricultural intensification by the increased inputs of agrochemicals has resulted in several negative environmental consequences. Currently, the precise use of agrochemicals is being recommended to improve crop yield and environmental health. Application of various precision agricultural practices is being promoted to attain the agricultural sustainability. Nanotechnology as a modern tool has been considered as a potential tool for the precise application of agrochemicals and efficient utilization by the crop plants in the agro-ecosystems. In this context, application of spent nano-catalysts in the agro-ecosystems has been increased considerably for the management of these spent catalysts. Numbers of studies have shown significant impact of spent nano-catalysts on plant germination and growth behaviours. In this chapter, a brief insight has been given on the development and application of novel nano-materials (NMs) in agriculture and environment along with their fate and behaviour. Further, recent developments in plant science regarding nano-biotechnology that focuses on agricultural practices, plant growth and yield are also emphasised. Moreover, an effort has been made to collate the studies dealing with utilization of spent nano-catalysts and nanomaterials used in various value-added products in the agricultural systems.
... It was shown that a certain length of shoot apices is essential to secure further regrowth after cryostorage, otherwise it was reported that too small shoot tips tend to die during the freeze-thaw cycle [37]. Jayasanka and Asaeda [38] in a recent review showed that the effects of microwaves on plants are dependent not only on the plant family and growth stage but also on the exposure duration, frequency, or power density. The complex mechanisms by which plants react to the exposure of electromagnetic fields are not entirely known. ...
Two distinct microwave power levels and techniques have been studied in two cases: low-power microwave (LPM) irradiation on in vitro Sequoia plants and high-power microwave (HPM) exposure on recovery rates of cryostored (-196°C) Sequoia shoot apices. Experimental variants for LPM exposure included: (a) in vitro plants grown in regular conditions (at 24 ± 1°C during a 16-h light photoperiod with a light intensity of 39.06 μEm(-2) s(-1) photosynthetically active radiation), (b) in vitro plants grown in the anechoic chamber with controlled environment without microwave irradiation, and (c) in vitro plants grown in the anechoic chamber with LPM irradiation for various times (5, 15, 30, 40 days). In comparison to control plants, significant differences in shoot multiplication and growth parameters (length of shoots and roots) were observed after 40 days of LPM exposure. An opposite effect was achieved regarding the content of total soluble proteins, which decreased with increasing exposure time to LPM. HPM irradiation was tested as a novel rewarming method following storage in liquid nitrogen. To our knowledge, this is the first report using this type of rewarming method. Although, shoot tips subjected to HPM exposure showed 28% recovery following cryostorage compared to 44% for shoot tips rewarmed in liquid medium at 22 ± 1 °C, we consider that the method represent a basis and can be further improved. The results lead to the overall conclusion that LPM had a stimulating effect on growth and multiplication of in vitro Sequoia plants, while the HPM used for rewarming of cryopreserved apices was not effective to achieve high rates of regrowth after liquid nitrogen exposure.
... A limited number of studies have addressed the effects of radiofrequency radiation on plants indicating that these effects depend on the plant family, growth stage, exposure duration, frequency, and power density, among other factors (Senavirathna and Takashi, 2013;Halgamuge et al., 2015). There are two papers warning on negative effects of radio frequencies from mobile phone masts on trees (Balmori, 2004;Waldmann-Selsam and Eger, 2013) and researchers have found very worrying effects in laboratory studies (Pesnya and Romanovsky, 2013). ...
The rate of scientific activity regarding the effects of anthropogenic electromagnetic radiation in the radiofrequency (RF) range on animals and plants has been small despite the fact that this topic is relevant to the fields of experimental biology, ecology and conservation due to its remarkable expansion over the past 20years. Current evidence indicates that exposure at levels that are found in the environment (in urban areas and near base stations) may particularly alter the receptor organs to orient in the magnetic field of the earth. These results could have important implications for migratory birds and insects, especially in urban areas, but could also apply to birds and insects in natural and protected areas where there are powerful base station emitters of radiofrequencies. Therefore, more research on the effects of electromagnetic radiation in nature is needed to investigate this emerging threat.
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After an indication of the numerous interveners who participated to this expertise study, and a presentation of the context, objective and methodology of this expertise, this report, based on a very large bibliography, discusses the various aspects of the '5G' deployment and the associated public controversy: situation of the deployment in France and abroad, problems raised, actors involved in the controversy, media content, health framework, and posture of the academic community. It describes international institutional positions with respect to health effects of the '5G' (by international bodies, foreign national institutions, and in the USA, Australia and New-Zealand, and Europe). In the next part, exposure data related to the '5G' are reported and compared: normative and regulatory framework, technological evolutions regrading the 5G bandwidth, assessment of the exposure level in the lower bandwidths. By referring to various public or scientific publications from different countries, it proposes a rather detailed overview of health effects related to the studied exposure (comments about scientific knowledge and acknowledgement, the different biological effects on the human body). Some recommendations, notably regarding the deployment of '5G', are finally presented. A second document presents the opinion of the ANSES (the French Agency for health safety) about the content of this report.
There is an urgent need to develop new compensatory and human-safe methods for controlling invasive Heracleum species. This research aimed to determine the effectiveness of H. sosnowskyi control under microwave radiation and biochemical changes in tissues and sap after irradiation. In field experiments in southern Poland, the plants were cut and irradiated with a device generating electromagnetic waves (2.45 GHz, 32.8 kW/m2). The control efficacy of plants in the rosette phase irradiated for 5, 10, or 15 min was 20%, 100%, and 100%, respectively. The control efficacy of plants in the flowering phase irradiated for 7.5 or 15 min was 66% and 100%. The metabolomic analysis of tissues and sap of irradiated H. sosnowskyi showed significant changes, mainly in the content and composition of proteins and sugars. In tissues, the treatments resulted in protein denaturation and significant changes in the metabolism of amino acids and the glyoxylate and galactose pathways. The sap was rich in sugars, glutamic acid, glutamine, homoserine, serine, and methionine. More changes in metabolite levels were observed in the tissues irradiated for 7.5 min. In conclusion, mi-crowave radiation of H. sosnowskyi for longer times, e.g., 10 and 15 min, efficiently controls it.
Ambient levels of nonionizing electromagnetic fields (EMF) have risen sharply in the last five decades to become a ubiquitous, continuous, biologically active environmental pollutant, even in rural and remote areas. Many species of flora and fauna, because of unique physiologies and habitats, are sensitive to exogenous EMF in ways that surpass human reactivity. This can lead to complex endogenous reactions that are highly variable, largely unseen, and a possible contributing factor in species extinctions, sometimes localized. Non-human magnetoreception mechanisms are explored. Numerous studies across all frequencies and taxa indicate that current low-level anthropogenic EMF can have myriad adverse and synergistic effects, including on orientation and migration, food finding, reproduction, mating, nest and den building, territorial maintenance and defense, and on vitality, longevity and survivorship itself. Effects have been observed in mammals such as bats, cervids, cetaceans, and pinnipeds among others, and on birds, insects, amphibians, reptiles, microbes and many species of flora. Cyto- and geno-toxic effects have long been observed in laboratory research on animal models that can be extrapolated to wildlife. Unusual multi-system mechanisms can come into play with non-human species — including in aquatic environments — that rely on the Earth’s natural geomagnetic fields for critical life-sustaining information. Part 2 of this 3-part series includes four online supplement tables of effects seen in animals from both ELF and RFR at vanishingly low intensities. Taken as a whole, this indicates enough information to raise concerns about ambient exposures to nonionizing radiation at ecosystem levels. Wildlife loss is often unseen and undocumented until tipping points are reached. It is time to recognize ambient EMF as a novel form of pollution and develop rules at regulatory agencies that designate air as ‘habitat’ so EMF can be regulated like other pollutants. Long-term chronic low-level EMF exposure standards, which do not now exist, should be set accordingly for wildlife, and environmental laws should be strictly enforced — a subject explored in Part 3.
In the perspective of seed technology, physical methods that were generally used to increase the plant production provide advantages as compared to conventional methods that use chemical substances. The impacts of physical treatments for invigoration in seeds tended to be addressed at different levels that include changes in the gene expression, the structural and morphological aspects, and metabolite or protein accumulation. The physical methods used for the pre-sowing treatments are irradiation with microwaves (MWs), magneto-priming, and ionizing radiations (IRs). “Magneto-priming” depends upon the use of magnetic fields and portrayed as a cheap, noninvasive, and eco-friendly technique with demonstrated gainful impacts on vigor, crop yield, and seed germination. Radiation such as gamma rays and X-rays has been generally viewed as a powerful contrivance in food technology and agricultural sciences. Positive impacts on seedling vigor, health, and germination were aroused by ultraviolet radiations (UV) that include UV-C and UV-A. Among all the identified physical treatments, a connected and basic research is yet expected to characterize the genotype, optimal dose required, and irradiation conditions that all depend on environment. Electron spin resonance has a huge prospective in regard to seed technology not correctly scrutinized to a point in time to end the treatment. Physical methods for the seed invigoration were described in the current chapter as well as emphasized to address the needs of seed technologists, trade makers, and producers by using the physical methods.
Mobile phones turned to be the most common form of public communication. Therefore, life on our planet continues wrapped in a “cloud” of non-ionizing radiations. Myrtus communis L. is an evergreen shrub, common in Mediterranean formations, exposed and adapted to two seasonally separated and qualitatively different environmental stresses. Thus, we considered it important to investigate the response of this tolerant species to emitted GSM non-ionizing radiations and compare it to already available data from thoroughly investigated plant species. Although the leaves of the exposed plants present unaffected tissue arrangement, their mesophyll cells accumulate large amounts of secondary metabolites, their photosynthetic pigments are dramatically reduced, the ROS counted are significantly increased and the presence of DDC, which cannot be detected in the leaves of the control plants, is recorded in high levels. The exposed leaves seem to experience a severe oxidative stress which probably induces DDC expression and the biosynthesis of the neurotransmitter dopamine, the activation of the shikimate pathway and, eventually, the accumulation of secondary metabolites.
Previous studies on microwave exposure on plants have revealed variations in sensitivity of plants to different microwave frequencies, exposure durations, and power intensities. However, the effects of different polarizations of microwaves on plants have not been studied. Therefore, we investigated the effect of horizontally and vertically polarized 2 GHz continuous microwaves on Myriophyllum aquaticum plants at 1.8 W m⁻² power density. The electric potential variation along the vascular tissues were investigated for 1.5 h and growth parameters, pigmentation, and H2O2 formation were studied during 48 h microwave exposure. Exposure to horizontally polarized microwaves, decreased standard deviation of electric potential variation and increased H2O2 content significantly. Vertically polarized microwaves increased the standard deviation of electric potential variation and photosynthetic pigments significantly. However, none of the polarizations altered growth parameters (shoot length, stem diameter, and internodal length). Thermographic images taken for 1 h continuous microwave exposure did not indicate alteration in the temperature of the plants for both vertical and horizontal polarities.
This study is focused on the biochemical changes induced by low level of 900 MHz frequency electromagnetic field in young plantlets (popcorn, i.e. Zea mays) provided of irradiated seeds. In this experiment, Zea mays seeds have been exposed to RF field of low power density, for different time intervals, between 0.5 and 36.0 hours. Assimilatory pigments and average nucleic acid content were assayed after 12 days of plantlets growth, by spectrophotometric methods. Certain inhibition of chlorophylls biosynthesis was noticed while a stimulatory effect upon the nucleic acid biosynthesis was revealed. Plant development was stimulated by radiation, as revealed by average length compared to controls.
The influence of radiofrequency (RF) and microwave (MU) electromagnetic waves of non thermal power density upon the assimilatory pigments in the vegetal tissues was studied. Increase in the photosynthetic pigment levels was found in both cases for relatively short exposure times (1 to 4 hours) while for longer exposure time (12 hours), in the plants exposed to microwaves, pigment content diminution was noticed The general increase of the photosynthesis efficiency was presumed to occur in the basis of indirect data provided by the enhanced ratio chlorophyll A/B. Slight stimulatory influence on the biomass accumulation was noticed in the case of MW exposure.
The objective of the present study was to investigate the changes of germination, growth rate and absorbance efficiency of photosynthetic pigments of maize grains after exposed to microwaves (MW). Experiment was carried out by exposing maize plants to continuous microwaves energy at (935.2-960.2 MHz with intensities 0.07-0.15 mW/cm2). The test plants and the control plants were subjected to the same environment during four weeks. The hypothesis was that plants exposed to MW would be different from those plants not exposed. The present experiment showed that germinating grains, growth rate (g dry wt./week and cm2/week) of exposed maize seedling and absorbance efficiency (η) significantly increased compared to the control. Also, photosynthetic pigments, total soluble sugar and total carbohydrates were positively affected by MW exposure. Microwaves altered the anatomical features of maize leaves by increasing midrib vascular bundle length, wing and assimilating layer thickness. In all measured variables differences between the control and the microwave treatment plants occurred.
The present study aims to investigate the effect of electromagnetic radiation (EMR) generated by mobile phones on the levels of amino acid neurotransmitters; glutamate, aspartate, GABA, glycine and taurine in the cortex of adult and young rats. Several studies showed that EMR could influence normal brain physiology, probably by changing cortical excitability. In the present study, adult and young rats were exposed to EMR for one hour/day. Amino acids were measured after 1 hour, 1, 2 and 4 months of daily EMR exposure and after 1 month of stopping exposure that extended daily for 4 months. The present data showed that in adult rats EMR induced significant changes in the cortical levels of some studied amino acids throughout the exposure periods. However, in young rats EMR induced significant changes after 4 months of daily exposure and after stopping exposure. It could be suggested that the changes in amino acid neurotransmitters may underlie the EMR-induced changes in cortical excitability.
We studied the effects of a weak sinusoidal and extremely-low-frequency (ELF) magnetic field (50 Hz, 100 μT) on the growth of cress seedlings (Lepidium sativum) that were also exposed to heat stress conditions at 40, 42 and 45°C for 40 min. The magnetic field was applied for 12 hr before or after the heat stress. The experiments showed that the magnetic field alleviated the inhibitory effect of the heat stress when applied previously, whereas afterwards, the heat stress or the magnetic field alone did not produce any significant growth effects. The results speak in favor of the findings by some researchers showing that biological systems under mild stress produce protective factors that decrease harmful effects of stronger stress and that, under certain circumstances, an oscillating magnetic field can work as a stress-protective agent.
Purpose:
We aimed to study the oxidative damage induced by radiofrequency electromagnetic radiation (RF-EMR) emitted by mobile telephones and the protective effect of garlic extract used as an anti-oxidant against this damage.
Materials and methods:
A total of 66 albino Wistar rats were divided into three groups. The first group of rats was given 1.8 GHz, 0.4 W/kg specific absorption rate (SAR) for 1 h a day for three weeks. The second group was given 500 mg/kg garlic extract in addition to RF-EMR. The third group of rats was used as the control group. At the end of the study, blood and brain tissue samples were collected from the rats.
Results:
After the RF-EMR exposed, the advanced oxidation protein product (AOPP) levels of brain tissue increased compared with the control group (p < 0.001). Garlic administration accompanying the RF-EMR, on the other hand, significantly reduced AOPP levels in brain tissue (p < 0.001). The serum nitric oxide (NO) levels significantly increased both in the first and second group (p < 0.001). However, in the group for which garlic administration accompanied that of RF-EMR, there was no difference in serum NO levels compared with the RF-EMR exposed group (p > 0.05). There was no significant difference among the groups with respect to malondialdehyde (MDA) levels in brain tissue and blood samples (p > 0.05). Similarly, no difference was detected among the groups regarding serum paroxonase (PON) levels (p > 0.05). We did not detect any PON levels in the brain tissue.
Conclusions:
The exposure of RF-EMR similar to 1.8 GHz Global system for mobile communication (GSM) leads to protein oxidation in brain tissue and an increase in serum NO. We observed that garlic administration reduced protein oxidation in brain tissue and that it did not have any effects on serum NO levels.
Mechanical irritation of trigger hairs and subsequent generation of action potentials have significant impact on photosynthesis and respiration in carnivorous Venus flytrap (Dionaea muscipula). Action potential-mediated inhibition of photosynthesis and stimulation of respiration is confined only to the trap and was not recorded in adjacent photosynthetic lamina. We showed that the main primary target of electrical signals on assimilation is in the dark enzymatic reaction of photosynthesis. Without doubt, the electrical signaling is costly, and the possible co-existence of such type of signals and photosynthesis in plant cell is discussed.
Plant responses to environmental changes are associated with electrical excitability and signaling; automatic and continuous measurements of electrical potential differences (DeltaEP) between plant tissues can be effectively used to study information transport mechanisms and physiological responses that result from external stimuli on plants. The generation and conduction of electrochemical impulses within plant different tissues and organs, resulting from abiotic and biotic changes in environmental conditions is reported. In this work, electrical potential differences are monitored continuously using Ag/AgCl microelectrodes, inserted 5 mm deep into sapwood at two positions in the trunks of several Avocado trees. Electrodes are referenced to a non polarisable Ag/AgCl microelectrode installed 20 cm deep in the soil. Systematic patterns of DeltaEP during absolute darkness, day-night cycles and different conditions of soil water availability are discussed as alternative tools to assess early plant stress conditions.
The indiscriminate use of wireless technologies, particularly of cell phones, has increased the health risks among living organisms including plants. We investigated the impact of cell phone electromagentic field (EMF) radiations (power density, 8.55 microW cm(-2)) on germination, early growth, proteins and carbohydrate contents, and activities of some enzymes in Vigna radiata. Cell phone EMF radiations significantly reduced the seedling length and dry weight of V radiata after exposure for 0.5, 1, 2, and 4 h. Furthermore, the contents of proteins and carbohydrates were reduced in EMF-exposed plants. However, the activities of proteases, alpha-amylases, beta-amylases, polyphenol oxidases, and peroxidases were enhanced in EMF-exposed radicles indicating their role in providing protection against EMF-induced stress. The study concludes that cell phone EMFs impair early growth of V radiata seedlings by inducing biochemical changes.
Plants are continuously exposed to a wide variety of perturbations including variation of temperature and/or light, mechanical forces, gravity, air and soil pollution, drought, deficiency or surplus of nutrients, attacks by insects and pathogens, etc., and hence, it is essential for all plants to have survival sensory mechanisms against such perturbations. Consequently, plants generate various types of intracellular and intercellular electrical signals mostly in the form of action and variation potentials in response to these environmental changes. However, over a long period, only certain plants with rapid and highly noticeable responses for environmental stresses have received much attention from plant scientists. Of particular interest to our recent studies on ultra fast action potential measurements in green plants, we discuss in this review the evidence supporting the foundation for utilizing green plants as fast biosensors for molecular recognition of the direction of light, monitoring the environment, and detecting the insect attacks as well as the effects of pesticides, defoliants, uncouplers, and heavy metal pollutants.
The physiological impact of nonionizing radiation has long been considered negligible. However, here we use a carefully calibrated stimulation system that mimics the characteristics (isotropy and homogeneity) of electromagnetic fields present in the environment to measure changes in a molecular marker (mRNA encoding the stress-related bZIP transcription factor), and show that low amplitude, short duration, 900 MHz EMF evokes the accumulation of this mRNA. Accumulation is rapid (peaking 5-15 min after stimulation) and strong (3.5-fold), and is similar to that evoked by mechanical stimulations.
As the nerve-mediated signaling in animals, long-distance signaling in plants is a prerequisite for plants to be able to perceive environmental stimuli and initiate adaptive responses. While intracellular signal transduction has been attracting considerable attentions, studies on long-distance signaling in plants has been relatively overlooked. Stomatal movements are well recognized as a model system for studies on cellular signal transduction. It has been demonstrated that the stomatal movements may be frequently tuned by long-distance signaling under various environmental stimuli. Stomatal movements can not only respond to persistent stress stimuli but also respond to shock stress stimuli. Stomatal responses to drought stress situations may be best characterized in terms of interwoven networks of chemical signaling pathways playing predominant roles in these adaptive processes. In cases of shock stress stimuli, stomatal movements can be more sensitively regulated through the long-distance signaling but with distinctive patterns not observed for drought or other persistent stresses. Here, the fundamental characteristics of stomatal movements and associated long-distance signaling are reviewed and the implications for plant responses to environmental stresses are discussed.
A review on the impact of radiofrequency radiation from wireless telecommunications on wildlife is presented. Electromagnetic radiation is a form of environmental pollution which may hurt wildlife. Phone masts located in their living areas are irradiating continuously some species that could suffer long-term effects, like reduction of their natural defenses, deterioration of their health, problems in reproduction and reduction of their useful territory through habitat deterioration. Electromagnetic radiation can exert an aversive behavioral response in rats, bats and birds such as sparrows. Therefore microwave and radiofrequency pollution constitutes a potential cause for the decline of animal populations and deterioration of health of plants living near phone masts. To measure these effects urgent specific studies are necessary.
The aim of this study is to understand the parameters regulating calcium ion distribution in leaves. Accumulation of ions in leaf tissue is in part dependent on import from the xylem. This import via the transpiration stream is more important for ions such as calcium that are xylem but not phloem mobile and cannot therefore be retranslocated. Accumulation of calcium was measured on bulk coriander leaf tissue (Coriandrum sativum L. cv. Lemon) using ion chromatography and calcium uptake was visualized using phosphor-images of (45)Ca(2+). Leaves of plants grown in hydroponics had elevated calcium in the centre of the leaf compared with the leaf margin, while K(+) was distributed homogeneously over the leaf. This calcium was shown to be localised to the mesophyll vacuoles using EDAX. Stomatal density and evapotranspiration (water loss per unit area of leaf) were equal at inner and outer sections of the leaf. Unequal ion distribution but uniformity of water loss suggested that there was a difference in the extent of uncoupling of calcium and water transport between the inner and outer leaf. Since isolated tissue from the inner and outer leaf were able to accumulate similar amounts of calcium, it is proposed that the spatial variation of leaf calcium concentration is due to differential ion delivery to the two regions rather than tissue/cell-specific differences in ion uptake capacity. There was a positive correlation between whole leaf calcium concentration and the difference in calcium concentration between inner and outer leaf tissue. Exposing the plants to increased humidity reduced transpiration and calcium delivery to the leaf and abolished this spatial variation of calcium concentration. Mechanisms of calcium delivery to leaves are discussed. An understanding of calcium delivery and distribution within coriander will inform strategies to reduce the incidence of calcium-related syndromes such as tip-burn and provides a robust model for the transport of ions and other substances in the leaf xylem.
Levels of DNA single-strand break were assayed in brain cells from rats acutely exposed to low-intensity 2450 MHz microwaves using an alkaline microgel electrophoresis method. Immediately after 2 h of exposure to pulsed (2 microseconds width, 500 pulses/s) microwaves, no significant effect was observed, whereas a dose rate-dependent [0.6 and 1.2 W/kg whole body specific absorption rate (SAR)] increase in DNA single-strand breaks was found in brain cells of rats at 4 h postexposure. Furthermore, in rats exposed for 2 h to continuous-wave 2450 MHz microwaves (SAR 1.2 W/kg), increases in brain cell DNA single-strand breaks were observed immediately as well as at 4 h postexposure.
We investigated the effects of acute (2-h) exposure to pulsed (2-micros pulse width, 500 pulses s(-1)) and continuous wave 2450-MHz radiofrequency electromagnetic radiation on DNA strand breaks in brain cells of rat. The spatial averaged power density of the radiation was 2mW/cm2, which produced a whole-body average-specific absorption rate of 1.2W/kg. Single- and double-strand DNA breaks in individual brain cells were measured at 4h post-exposure using a microgel electrophoresis assay. An increase in both types of DNA strand breaks was observed after exposure to either the pulsed or continuous-wave radiation, No significant difference was observed between the effects of the two forms of radiation. We speculate that these effects could result from a direct effect of radiofrequency electromagnetic energy on DNA molecules and/or impairment of DNA-damage repair mechanisms in brain cells. Our data further support the results of earlier in vitro and in vivo studies showing effects of radiofrequency electromagnetic radiation on DNA.
To examine whether a simulated mobile telephone transmission at 915 MHz has an effect on cognitive function in man.
Thirty-six subjects in two groups were each given two training sessions and then three test sessions in a randomized three-way cross-over design. About 1 W mean power at 915 MHz from a quarter-wave antenna mounted on a physical copy of an analogue phone, as a sine wave, or modulated at 217 Hz with 12.5% duty cycle, or no power, was applied to the left squamous temple region of the subjects while they undertook a series of cognitive function tests lasting approximately 25-30 min. The second group was investigated for sleep, consumption of alcohol and beverages, and any other substances that might affect performance.
In both groups, the only test affected was the choice reaction time and this showed as an increase in speed (a decrease in reaction time). There were no changes in word, number or picture recall, or in spatial memory. While an effect of visit-order was evident suggesting a learning effect of repeat tests, the design of the study allowed for this. Additionally, there was no systematic error introduced as a result of consumption of substances or sleep time.
There was evidence of an increase in responsiveness, strongly in the analogue and less in the digital simulation, in choice reaction time. This could be associated with an effect on the angular gyrus that acts as an interface between the visual and speech centres and which lies directly under and on the same side as the antenna. Such an effect could be consistent with mild localized heating, or possibly a non-thermal response, which is nevertheless power-dependent.
Abstract Plants growing in natural environments are exposed to radiofrequency electromagnetic radiation (EMR) emitted by various communication network base stations. The environmental concentration of this radiation is increasing rapidly with the congested deployment of base stations. Although numerous scientific studies have been conducted to investigate the effects of EMR on the physiology of humans and animals, there have been few attempts to investigate the effects of EMR on plants. In this study, we attempted to evaluate the effects of EMR on photosynthesis by investigating the chlorophyll fluorescence (ChF) parameters of duckweed fronds. During the experiment, the fronds were tested with 2, 2.5, 3.5, 5.5 and 8 GHz EMR frequencies, which are not widely studied even though there is a potentially large concentration of these frequencies in the environment. The duckweed fronds were exposed to EMR for 30 min, 1 h and 24 h durations with electric field strength of 45-50 V/m for each frequency. The results indicated that exposure to EMR causes a change in the non-photochemical quenching of the duckweeds. The changes varied with the frequency of the EMR and were time-varying within a particular frequency. The temperature remained unchanged in the duckweed fronds upon exposure to EMR, which confirms that the effect is non-thermal.
Young spruce and beech trees were planted in field plots and exposed to 2450-MHz microwave radiation generated by a 600-W magnetron source. Power flux densities (PFD) ranged from 0.007 to 300 W/m2, depending on the location within the plots. Microwave exposure was permanent during 3.5 years. Heating effects of the microwave radiation were estimated by measuring the hydrolysis rate of exposed sucrose solutions. This method revealed a temperature increase of ∼4°C at the highest PFDs. During the whole exposure period, the microwave radiation caused no visual symptoms of damage. PFD had no effect on crown transparency, a parameter commonly estimated in forest condition inventories. Height growth was similar at all PFDs for both species, as was photosynthesis in beech leaves, determined by chlorophyll fluorescence measurements. A negative relationship existed between foliar concentrations of calcium and sulfur in beech and PFD during the first 2 years of exposure. However, the concentrations of both nutrients remained within the sufficiency range. In the third year of exposure, the effect was absent. The microwave effect on calcium is discussed in connection with literature data.
Action potentials and resting potentials were measured in potato plants (Solanum tuberosum L.) under different physiological conditions. External stimuli (e.g. changing temperature, wounding or exposing plant leaves or soil to certain chemical compounds) cause an action potential to be generated and change the restingpotential from the original steady state level. The amplitude, polarity and the speed of action potential propagation depend onthe type of external stimuli or stress. The kinetics and amplitude of the resting potential also change depending on the nature of the external stimuli. For example, in the presence of leaf-feeding larvae of the Colorado potato beetle (Leptinortsa decemlineata (Say); Coleoptera; Chrysomelidae), the speed at which insect-induced action potentials moved downward through the stem was about 0.05 cm s−1. The action potentials propagated downwards from the damaged leaf along the stem. When the upper leaves of potato plants were sprayed with 0.3 ml of 1 mM aqueous solution of pentachlorophenol, the effect was almost identical to that induced by Colorado potato beetle. To our knowledge, this is the first demonstration of action potential generation in plants induced by insect damage or chemical injury.
Chlorophyll fluorescence was measured under both laboratory and greenhouse conditions in an effort to develop a quick, reliable, and inexpensive laboratory procedure capable of predicting heat stress experienced by tomato ( Lycoper- sicon esculentum Mill.) under greenhouse conditions. The laboratory tests consisted of measurements of the ratio of variable to maximal chlorophyll fluorescence (F v/Fm) performed on leaf discs taken from whole tomato leaves and placed on a temperature controlled plate. Comparisons were made with greenhouse measurements of the same parameter conducted on intact leaves of whole plants exposed to different temperature treatments imposed by manipulation of the aerial environment of the greenhouse. Dark adaption periods ranging from 15 min to all day in the greenhouse and temperature exposure periods ranging from 5 min to 60 min in the laboratory were compared to find the best correlation between the two tests. Best agreement was obtained with 60 min treatment times in the laboratory and 60 min dark adaption periods in the greenhouse. Fv/Fm decreased quadratically with increasing leaf temperature in a similar fashion in both tests, suggesting that the laboratory approach can adequately predict plant response to greenhouse heat stress.
Radio frequency and microwave radiations are a part of non-ionizing electromagnetic radiations present in the environment and are now being perceived as health risks. The present study was performed to investigate the effect of 2.45 GHz microwave radiation on reproductive pattern of male Wistar rats. Animals were exposed at 2.45 GHz frequency with 0.34 mW cm−2 power density continuously for 2 h day−1 for 35 days, where the whole body specific absorption rate was 0.11 W kg−1. Exposure occurred in a ventilated plexiglass cage and kept in anechoic chamber at a distance of 2 m from the horn antenna. In the present study, apoptosis was tested using terminal deoxynucleotide transferase dUTP nick end labeling assay. Normal and apoptotic sperm cells were also quantified by flow cytometry. Antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)) were also determined to confirm any mutagenic effects, such as DNA fragmentation. Chronic exposure to these radiations produced formation of apoptotic cells in testis. In addition, a significant decrease in the levels of GPx, and SOD activities as well as an increase in CAT activity was observed in the exposed group. These results indicate that a low level exposure of microwave radiations exerts a negative impact on male reproductive system function.
Partly vernalised plantlets of Triticum aestivum var. Grana, cultivated in vitro, were subjected for varying lengths of time to electric current of different voltages with the anode (+) attached to the first leaf and the cathode (-) to the medium and vice versa. Twenty-four hours after the treatment, the plantlets were planted into the pots. The percentage of reproductive plants and their time to heading was recorded. The positive electric current greatly increased (in the range of 60 to 90 %) the percentage of generative plants as compared to the controls (5 %) almost irrespective of the voltage and duration of the treatment. The reverse polarity (-) exerted a much weaker effect. The time to heading was almost unchanged by the electric treatments. It was deduced that the effect of electric current replaced part of the chilling requirement and shifted the developmental state to reproductive phase. The experiments are in progress to elucidate the interaction between electric current and chemical signals that may be involved in flower induction.
The goal of this study was to compare the cytotoxic and genotoxic effects of plutonium-239 alpha particles and GSM 900 modulated mobile phone radiation in the Allium cepa test. Three groups of bulbs were exposed to mobile phone radiation during 0 (sham), 3 and 9h. A positive control group was treated during 20min with plutonium-239 alpha-radiation. Mitotic abnormalities, chromosome aberrations, micronuclei and mitotic index were analyzed. Exposure to alpha-radiation from plutonium-239 and exposure to modulated radiation from mobile phone during 3 and 9h significantly increased the mitotic index. GSM 900 mobile phone radiation as well as alpha-radiation from plutonium-239 induced both clastogenic and aneugenic effects. However, the aneugenic activity of mobile phone radiation was more pronounced. After 9h of exposure to mobile phone radiation, polyploid cells, three-groups metaphases, amitoses and some unspecified abnormalities were detected, which were not registered in the other experimental groups. Importantly, GSM 900 mobile phone radiation increased the mitotic index, the frequency of mitotic and chromosome abnormalities, and the micronucleus frequency in a time-dependent manner. Due to its sensitivity, the A. cepa test can be recommended as a useful cytogenetic assay to assess cytotoxic and genotoxic effects of radiofrequency electromagnetic fields.
Although the effects of high-frequency electromagnetic fields on biological systems have been studied frequently, unequivocal results have rarely been obtained, primarily because suitably controlled experiments could not be performed. In the present work, tomato plants were exposed to a homogeneous and isotropic field (900 MHz) using a mode stirred reverberation chamber, and the stress-related transcripts (calmodulin, protease inhibitor and chloroplast mRNA-binding protein) were assayed by real-time quantitative PCR. Exposure to an electromagnetic field induced a biphasic response, in which the levels of all three transcripts increased four- to six-fold 15 min after the end of electromagnetic stimulation, dropped to close to initial levels by 30 min, and then increased again at 60 min. We deliberately focused on the very early molecular responses to high-frequency electromagnetic fields in order to minimize secondary effects.
Plants have evolved complex regulatory mechanisms in adapting to various environmental stresses. One of the consequences of many stresses is an increase in the cellular concentration of reactive oxygen species (ROS), which are subsequently converted to hydrogen peroxide (H 2 O 2). An oxidative burst caused by biotic or abiotic stress leads to a disturbance in the cellular redox balance and is highly toxic to cells. Recently, H 2 O 2 , in addition to being a toxicant, has been regarded as a signaling molecule and a regulator of the expression of some genes in cells. These include genes encoding antioxidants, cell rescue/defense proteins, and signaling proteins such as kinase, phosphatase, and transcription factors. Here, we review the function of H 2 O 2 as a signal molecule in the transduction of stress signals to the alteration of expression profiles of target genes, and we summarize the evidence that H 2 O 2 acts as a stress signal in plants.
We studied the effects of a change in flowering date on the reproductive output of a short-day annual plant, Xanthium canadense. The flowering date was changed by photoperiodic manipulation to 1 month earlier or later than the natural flowering date.
Plants with the natural flowering date attained the highest reproductive output. For those flowering 1 month earlier or later,
the reproductive output was decreased by 42% or 23%, respectively. The reproductive output was analyzed as the product of
the biomass production during the reproductive period and its allocation to the reproductive organs. Although delay in flowering
increased biomass production, it decreased its fractional allocation to the reproductive organs. The highest reproductive
output in the natural flowering plants resulted from a compromise between these two effects of flowering. Plants flowering
earlier had higher translocation rates to the reproductive organs and accelerated plant senescence. Later flowering caused
a reduction in biomass translocation to the reproductive organs and thus extended the reproductive period. These experimental
results are discussed in relation to the cost of reproduction and the optimal time for flowering that maximizes the final
reproductive output. It is suggested that the natural flowering time maximized the reproductive output while minimizing the
cost of reproduction.
Industrial use of microwave radiation as an alternative to conventional thermal heating has generated interest recently mainly because of the drastic reduction in the processing time. In spite of its wide application, its chemical mechanism of interaction with materials has not been well understood. The current debate on the alternative use of microwave radiation to conventional thermal heating is on the involvement of a microwave specific effect other than the well accepted dielectric heating. There are reports of various reactions which show similar kinetics under both microwave and thermal methods at similar temperatures suggesting simple dielectric heating of materials by microwaves. There are also reports which show a clear reaction rate enhancement under microwave radiation compared to the thermal method under similar reaction conditions and temperatures indicating a microwave specific effect other than the simple dielectric heating of materials. This paper will discuss the above conflicting results reported in the literature.
When users want broadband Internet service, they're generally restricted to a T1, DSL, or cable-modem-based connection. However, these wireline infrastructures can be considerably more expensive and time consuming to deploy than a wireless one. In addition, rural areas and developing countries frequently lack optical fiber or copper-wire infrastructures for broadband services, and providers are unwilling to install the necessary equipment for regions with little profit potential. Many residents thus must do without broadband service. Wireless approaches could address this problem. Therefore, proponents are advocating WiMax (worldwide interoperability for microwave access), a technology based on an evolving standard for point-to-multipoint wireless networking. Carriers can use WiMax to provide wireless Internet service via transceivers to users' antennas. In addition to IEEE 802.16, WiMax addresses the European Telecommunications Standards Institute's (ETSI) similar high-performance radio metropolitan area network (HiperMAN) broadband standard.
The involvement of electrical signaling in the regulation of gas exchange was checked with maize plants subjected to a drying cycle of 5 days in a controlled environment. Gas exchange and extracellular electrical potential measurements were made on attached leaves. The CO2 uptake and transpiration rate decreased in drying soil and increased to their original values after irrigation. Continuous records of the electrical potential difference between two surface points were made on the same leaf on which the gas measurements were performed. A daily rhythm was clearly visible and seemed to be correlated with the soil water status. After soil drying the plants were watered and increases in CO2 and H2O exchange have been demonstrated to follow the arrival of an electrical signal in the leaves. When a dye solution was applied to the roots its uptake and movement to the leaves was observed continuously by microscopy showing that the increase of gas exchange 12–15 min after irrigation could not be triggered by water ascent. By using severed aphid stylets it was shown that sieve tubes served as a pathway for electrical signal transmission. Furthermore, roots were water-stressed by addition of non-penetrating osmolyte to the root medium. The gas exchange of the leaves decreased clearly 6 min after application of polyethylene glycol 6000 (PEG, −0.5 MPa water potential). Comparative measurements of the sieve tube electrical potential indicated that PEG-induced water stress evoked a propagating depolarization of the potential. Other osmolytes (100 mM NaCl) caused similar results showing that the leaf responses are not related to any specific toxic effect of PEG. Thus, the results strongly support the view that electrical signaling plays an important role in root to shoot communication of water-stressed plants.
During the last couple of decades, there has been a tremendous increase in the use of cell phones. It has significantly added to the rapidly increasing EMF smog, an unprecedented type of pollution consisting of radiation in the environment, thereby prompting the scientists to study the effects on humans. However, not many studies have been conducted to explore the effects of cell phone EMFr on growth and biochemical changes in plants. We investigated whether EMFr from cell phones inhibit growth of Vigna radiata (mung bean) through induction of conventional stress responses. Effects of cell phone EMFr (power density: 8.55 µW cm− 2; 900 MHz band width; for ½, 1, 2, and 4 h) were determined by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H2O2) content, root oxidizability and changes in levels of antioxidant enzymes. Our results showed that cell phone EMFr significantly inhibited the germination (at ≥2 h), and radicle and plumule growths (≥1 h) in mung bean in a time-dependent manner. Further, cell phone EMFr enhanced MDA content (indicating lipid peroxidation), and increased H2O2 accumulation and root oxidizability in mung bean roots, thereby inducing oxidative stress and cellular damage. In response to EMFr, there was a significant upregulation in the activities of scavenging enzymes, such as superoxide dismutases, ascorbate peroxidases, guaiacol peroxidases, catalases and glutathione reductases, in mung bean roots. The study concluded that cell phone EMFr inhibit root growth of mung bean by inducing ROS-generated oxidative stress despite increased activities of antioxidant enzymes.
as already mentioned, can detect fields that wide variety of non-thermal -effects induced by low intensity microwave (both pulsed
Effects of high-frequency, continuous wave (CW) electromagnetic fields on mung beans (Vigna radiata L.) and water convolvuluses (Ipomoea aquatica Forssk.) were studied at different growth stages (pre-sown seed and early seedling). Specifically, the effects of the electromagnetic source's power and duration (defined as power-duration level) on the growth of the two species were studied. Mung beans and water convolvuluses were exposed to electromagnetic fields inside a specially designed chamber for optimum field absorption, and the responses of the seeds to a constant frequency at various power levels and durations of exposure were monitored. The frequency used in the experiments was 425 MHz, the field strengths were 1 mW, 100 mW, and 10 W, and the exposure durations were 1, 2, and 4 h. Results show that germination enhancement is optimum for the mung beans at 100 mW/1 h power-duration level, while for water convolvuluses the optimum germination power-duration level was 1 mW/2 h. When both seed types were exposed at the early sprouting phase with their respective optimum power-duration levels for optimum seed growth, water convolvuluses showed growth enhancement while mung bean sprouts showed no effects. Water content analysis of the seeds suggests thermal effects only at higher field strength.
Increasing evidence indicates that oxidative stress may be involved in the adverse effects of radiofrequency (RF) radiation on the brain. Because mitochondrial DNA (mtDNA) defects are closely associated with various nervous system diseases and mtDNA is particularly susceptible to oxidative stress, the purpose of this study was to determine whether radiofrequency radiation can cause oxidative damage to mtDNA. In this study, we exposed primary cultured cortical neurons to pulsed RF electromagnetic fields at a frequency of 1800 MHz modulated by 217 Hz at an average special absorption rate (SAR) of 2 W/kg. At 24 h after exposure, we found that RF radiation induced a significant increase in the levels of 8-hydroxyguanine (8-OHdG), a common biomarker of DNA oxidative damage, in the mitochondria of neurons. Concomitant with this finding, the copy number of mtDNA and the levels of mitochondrial RNA (mtRNA) transcripts showed an obvious reduction after RF exposure. Each of these mtDNA disturbances could be reversed by pretreatment with melatonin, which is known to be an efficient antioxidant in the brain. Together, these results suggested that 1800 MHz RF radiation could cause oxidative damage to mtDNA in primary cultured neurons. Oxidative damage to mtDNA may account for the neurotoxicity of RF radiation in the brain.
101 publications are exploited which have studied genotoxicity of radiofrequency electromagnetic fields (RF-EMF) in vivo and in vitro. Of these 49 report a genotoxic effect and 42 do not. In addition, 8 studies failed to detect an influence on the genetic material, but showed that RF-EMF enhanced the genotoxic action of other chemical or physical agents. The controversial results may in part be explained by the different cellular systems. Moreover, inconsistencies may depend from the variety of analytical methods being used, which differ considerably with respect to sensitivity and specificity. Taking altogether there is ample evidence that RF-EMF can alter the genetic material of exposed cells in vivo and in vitro and in more than one way. This genotoxic action may be mediated by microthermal effects in cellular structures, formation of free radicals, or an interaction with DNA-repair mechanisms.
A major concern of the adverse effects of exposure to non-ionizing electromagnetic field (EMF) is cancer induction. Since the majority of cancers are initiated by damage to a cell's genome, studies have been carried out to investigate the effects of electromagnetic fields on DNA and chromosomal structure. Additionally, DNA damage can lead to changes in cellular functions and cell death. Single cell gel electrophoresis, also known as the 'comet assay', has been widely used in EMF research to determine DNA damage, reflected as single-strand breaks, double-strand breaks, and crosslinks. Studies have also been carried out to investigate chromosomal conformational changes and micronucleus formation in cells after exposure to EMF. This review describes the comet assay and its utility to qualitatively and quantitatively assess DNA damage, reviews studies that have investigated DNA strand breaks and other changes in DNA structure, and then discusses important lessons learned from our work in this area.
Studying effects of mobile phone base station signals on health have been discouraged by authoritative bodies like WHO International EMF Project and COST 281. WHO recommended studies around base stations in 2003 but again stated in 2006 that studies on cancer in relation to base station exposure are of low priority. As a result only few investigations of effects of base station exposure on health and wellbeing exist. Cross-sectional investigations of subjective health as a function of distance or measured field strength, despite differences in methods and robustness of study design, found indications for an effect of exposure that is likely independent of concerns and attributions. Experimental studies applying short-term exposure to base station signals gave various results, but there is weak evidence that UMTS and to a lesser degree GSM signals reduce wellbeing in persons that report to be sensitive to such exposures. Two ecological studies of cancer in the vicinity of base stations report both a strong increase of incidence within a radius of 350 and 400 m respectively. Due to the limitations inherent in this design no firm conclusions can be drawn, but the results underline the urgent need for a comprehensive investigation of this issue. Animal and in vitro studies are inconclusive to date. An increased incidence of DMBA induced mammary tumors in rats at a SAR of 1.4 W/kg in one experiment could not be replicated in a second trial. Indications of oxidative stress after low-level in vivo exposure of rats could not be supported by in vitro studies of human fibroblasts and glioblastoma cells.
The effects of exposure to radiofrequency electromagnetic fields (RF-EMFs) on seed germination, primary root growth as well as mitotic activity and mitotic aberrations in root meristematic cells were examined in Allium cepa L. cv. Srebrnjak Majski. Seeds were exposed for 2h to EMFs of 400 and 900MHz at field strengths of 10, 23, 41 and 120Vm(-1). The effect of longer exposure time (4h) and field modulation was investigated at 23Vm(-1) as well. Germination rate and root length did not change significantly after exposure to radiofrequency fields under any of the treatment conditions. At 900MHz, exposures to EMFs of higher field strengths (41 and 120Vm(-1)) or to modulated fields showed a significant increase of the mitotic index compared with corresponding controls, while the percentage of mitotic abnormalities increased after all exposure treatments. On the other hand, at 400MHz the mitotic index increased only after exposure to modulated EMF. At this frequency, compared with the control higher numbers of mitotic abnormalities were found after exposure to modulated EMF as well as after exposure to EMFs of higher strengths (41 and 120Vm(-1)). The types of aberration induced by the EMFs of both frequencies were quite similar, mainly consisting of lagging chromosomes, vagrants, disturbed anaphases and chromosome stickiness. Our results show that non-thermal exposure to the radiofrequency fields investigated here can induce mitotic aberrations in root meristematic cells of A. cepa. The observed effects were markedly dependent on the field frequencies applied as well as on field strength and modulation. Our findings also indicate that mitotic effects of RF-EMF could be due to impairment of the mitotic spindle.
Two thermophilic and thermostable enzymes, isolated from Sulfolobus solfataricus, S-adenosylhomocysteine hydrolase and 5'-methylthioadenosine phosphorylase, were exposed to 10.4 GHz microwave radiation in order to discriminate between thermal and non-thermal microwave effects. The exposure causes a non-thermal, irreversible and time-dependent inactivation of both enzymes; the inactivation rate is related to the energy absorbed and is independent of the enzyme concentration. The influence of salts on enzyme inactivation has also been investigated. Conformational changes of S-adenosylhomocysteine hydrolase, detected by fluorescence and circular dichroism techniques, suggest that microwaves induce protein structural rearrangements not related to temperature.
Due to the extensive use of electromagnetic fields in everyday life, more information is required for the detection of mechanisms of interaction and the possible side effects of electromagnetic radiation on the structure and function of the organism. In this paper, we study the effects of low-power microwaves (2.45 GHz) on the membrane fluidity of rod photoreceptor cells. The retina is expected to be very sensitive to microwave irradiation due to the polar character of the photoreceptor cells [Biochim. Biophys. Acta 1273 (1995) 217] as well as to its high water content [Stud. Biophys. 81 (1981) 39].
We have examined whether non-thermal exposures of cultures of the human endothelial cell line EA.hy926 to 900 MHz GSM mobile phone microwave radiation could activate stress response. Results obtained demonstrate that 1-hour non-thermal exposure of EA.hy926 cells changes the phosphorylation status of numerous, yet largely unidentified, proteins. One of the affected proteins was identified as heat shock protein-27 (hsp27). Mobile phone exposure caused a transient increase in phosphorylation of hsp27, an effect which was prevented by SB203580, a specific inhibitor of p38 mitogen-activated protein kinase (p38MAPK). Also, mobile phone exposure caused transient changes in the protein expression levels of hsp27 and p38MAPK. All these changes were non-thermal effects because, as determined using temperature probes, irradiation did not alter the temperature of cell cultures, which remained throughout the irradiation period at 37 +/- 0.3 degrees C. Changes in the overall pattern of protein phosphorylation suggest that mobile phone radiation activates a variety of cellular signal transduction pathways, among them the hsp27/p38MAPK stress response pathway. Based on the known functions of hsp27, we put forward the hypothesis that mobile phone radiation-induced activation of hsp27 may (i) facilitate the development of brain cancer by inhibiting the cytochrome c/caspase-3 apoptotic pathway and (ii) cause an increase in blood-brain barrier permeability through stabilization of endothelial cell stress fibers. We postulate that these events, when occurring repeatedly over a long period of time, might become a health hazard because of the possible accumulation of brain tissue damage. Furthermore, our hypothesis suggests that other brain damaging factors may co-participate in mobile phone radiation-induced effects.
Traditionally, reactive oxygen intermediates (ROIs) were considered to be toxic by-products of aerobic metabolism, which were disposed of using antioxidants. However, in recent years, it has become apparent that plants actively produce ROIs as signaling molecules to control processes such as programmed cell death, abiotic stress responses, pathogen defense and systemic signaling. Recent advances including microarray studies and the development of mutants with altered ROI-scavenging mechanisms provide new insights into how the steady-state level of ROIs are controlled in cells. In addition, key steps of the signal transduction pathway that senses ROIs in plants have been identified. These raise several intriguing questions about the relationships between ROI signaling, ROI stress and the production and scavenging of ROIs in the different cellular compartments.
In this report we examined the effects of a discontinuous radio frequency (RF) signal produced by a GSM multiband mobile phone (900/1,900 MHz; SAR approximately 1.4 W/kg) on Drosophila melanogaster, during the 10-day developmental period from egg laying through pupation. As found earlier with low frequency exposures, the non-thermal radiation from the GSM mobile phone increased numbers of offspring, elevated hsp70 levels, increased serum response element (SRE) DNA-binding and induced the phosphorylation of the nuclear transcription factor, ELK-1. The rapid induction of hsp70 within minutes, by a non-thermal stress, together with identified components of signal transduction pathways, provide sensitive and reliable biomarkers that could serve as the basis for realistic mobile phone safety guidelines.
Four Arabidopsis thaliana ecotypes were grown at 14 degrees C and 22 degrees C under two light conditions (300 microE m-2 s-1 or 150 microE m-2 s-1) and the effect of temperature on their growth and flowering time was studied. Flowering occurred within 31 days (experimental period) at 22 degrees C, whereas a decrease in growth temperature resulted in a delay in flowering (63 days) under both light conditions. At 14 degrees C, membrane-bound APX (tAPX) activity decreased and total chlorophyll (Chl) content increased with growth under both light conditions. However, at 22 degrees C, the tAPX activity increased and total Chl content decreased with growth under both light conditions. These results suggest that at 22 degrees C oxidative stress was high under both light conditions and consequently Chl content decreased under stressful conditions or vice versa for all the four A. thaliana ecotypes studied. Under both the temperature and light conditions, soluble APX activity showed an irregular pattern of growth. The increase in tAPX activity, with growth only at 22 degrees C but not at 14 degrees C, suggests increased H2O2 formation in flowering plants at 22 degrees C for all the four A. thaliana ecotypes studied. Before flowering, the tAPX activity showed a significantly negative correlation with flowering time. Higher oxidative stress in the lower-latitude ecotypes might induce earlier flowering than the higher-latitude ecotypes. From these results, we propose a hypothesis that H2O2 is one of the possible factors in flower induction.
In two previous studies we demonstrated that radiofrequency electromagnetic fields (RF EMF) similar to those emitted by digital radiotelephone handsets affect brain physiology of healthy young subjects exposed to RF EMF (900 MHz; spatial peak specific absorption rate [SAR] 1 W/kg) either during sleep or during the waking period preceding sleep. In the first experiment, subjects were exposed intermittently during an 8 h nighttime sleep episode and in the second experiment, unilaterally for 30 min prior to a 3 h daytime sleep episode. Here we report an extended analysis of the two studies as well as the detailed dosimetry of the brain areas, including the assessment of the exposure variability and uncertainties. The latter enabled a more in depth analysis and discussion of the findings. Compared to the control condition with sham exposure, spectral power of the non-rapid eye movement sleep electroencephalogram (EEG) was initially increased in the 9-14 Hz range in both experiments. No topographical differences with respect to the effect of RF EMF exposure were observed in the two experiments. Even unilateral exposure during waking induced a similar effect in both hemispheres. Exposure during sleep reduced waking after sleep onset and affected heart rate variability. Exposure prior to sleep reduced heart rate during waking and stage 1 sleep. The lack of asymmetries in the effects on sleep EEG, independent of bi- or unilateral exposure of the cortex, may indicate involvement of subcortical bilateral projections to the cortex in the generation of brain function changes, especially since the exposure of the thalamus was similar in both experiments (approx. 0.1 W/kg).