Searching for the Perfect Wave — biological effect of RF electromagnetic fields
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Abstract: There is a growing concern in the population about the effects that environmental exposure to any source of “uncontrolled” radiation may have on public health. Anxiety arises from the controversial knowledge about the effect of electromagnetic field (EMF) exposure to cells and organisms but most of all concerning the possible causal relation to human diseases. Here we reviewed those in vitro and in vivo and epidemiological works that gave a new insight about the effect of radio frequency (RF) exposure, relating to intracellular molecular pathways that lead to biological and functional outcomes.
Who Is Afraid of “Electrosmog”?
Electromagnetic fields of all frequencies represent one of the most common environmental influences, and EMF exposure levels of the population will continue to increase with technological advances. Since the 1960s, anxiety and speculation has grown among the public about the consequence of casual exposure to or continuous interaction with different sources of EMF emission [4]. The neologism “electrosmog” is an indication of how this concern has spread among the population [5].
The reality is that the level of RF radiation to which people is exposed is growing exponentially. This is suggested to correlate with an associated risk of glial tumor [6] Moreover, the specific use of several devices such as microwave ovens and mobile phones is today prevalent and some groups of study suggested that actual methods and parameters of evaluation of absorption underestimate the real impact of RF exposure
[We] focus on the latest acquired information on the possible effects on biological systems of exposure to radiofrequency electromagnetic waves (RF-EMF) as the exposure to this range of radiations accompany the use of common devices such as mobile phones and Wi-Fi radiations. Until recently, experimental and epidemiological data for the RF range were very sparse and the results of numerous in vitro and in vivo studies were rather conflicting.
The Effect of RF Exposure on in Vitro Models: Finding the Pathways
It has long been speculated that mobile phone radiation (radiofrequency-modulated electromagnetic fields, RF-EMF) alters protein expression in human cell lines [20,21].
To draw a complete picture of lymphoblastic leukemia response to RF exposure, further investigation was recently carried out by microarray analysis on cancer cells. Trivino Pardo and coworkers [31] confirmed that high frequency EMFs affect cellular systems by acting as genotoxic agents. Significant changes in expression levels of genes involved in DNA repair, cell cycle arrest, apoptosis, chromosomal organization, and angiogenesis were observed after both short- and long-term 900 MHz EMF exposure. … It appears that RF, acting as a genotoxic agent, quickly induces DNA damage by activating early on cell death effectors of apoptotic response. With respect to aggressiveness of the tumor cells, altered gene expression was detected for angiogenesis, differentiation and regulation of the cytoskeleton…
One of the most frequent findings of in vitro models after EMF-RF exposure is the increase of oxidative stress-related events that lead to cell damage. This event is causally related to neurodegeneration that underlie severe pathologies such as Alzheimer’s disease or Parkinson’s…
… a growing bulk of literature indicates calcium-related machinery as a potential mediator for EMF effect, both in vitro and in vivo. Maskey [44,45] hypothesized that repeated five-hour sessions of daily exposure to rats of 835 MHz (SAR = 1.6 W/kg) might alter permeability of cell membrane in hippocampal pyramidal cells, thereby jeopardizing neuronal connectivity…
What emerges from these reports, and several earlier ones, is that RF exposure is bad for cell survival and that there are some districts such as the brain, in which cells are extremely sensitive to RF exposure…
Another easily amenable in vivo model is Drosophila melanogaster used to study DNA fragmentation after 900 MHz exposure through its reproductive ability [40]. To investigate the effect of RF exposure on morphology, biology and functions of mammalian brain and neuronal network functions [53,54] rodents are intensively used. In 2011, Ntzouni et al. [55] carried out a study in order to investigate whether short-term memory is affected by ordinary mobile phone exposure…
The involvement of RF in several neuropathologies has received wide consideration [58]. Among the neurodegenerative diseases, Alzheimer’s disease (AD) has long been associated with RF exposure. AD is in fact characterized by the presence of well-established morphological (neurofibrillary tangles and β amyloid deposition in cortical and hippocampal neurons) and functional (behavioral and memory alterations) biomarkers. One of the most relevant features of Alzheimer’s seems to be the increased reactive oxygen species (ROS) production and related inflammation of cortical and subcortical tissue in AD brains. There are many reports of ROS increase after RF exposure in the brain [59,60] that in turn give rise to a cascade of molecular events involving anti-oxidative enzyme activities, protein kinase C, creatine kinase and finally the pro-apoptotic enzyme caspase 3. RF-dependent expression of reactive astroglia was also detected [56]. There seems to be a causal relation between AD development and RF exposure…
Few reports concern Parkinson’s disease (PD) and RF exposure. Parkinson’s is another severe neurodegenerative disease and is caused by a degeneration of dopaminergic neurons in the Substantia Nigra of the midbrain. A possible causal link between RF and PD has been suggested [67,68]…
In relation to the CNS, it is worth mentioning a few studies on the effect of RF on neuronal blood barrier permeability. Blood-brain barrier (BBB) and blood-retinal barrier [72] are safety mechanisms that regulate molecular exchanges between blood circulation and neuronal tissues. Variation of barrier permeability may occur as a consequence of pathologies or traumas, such as after stroke. However, an increase of permeability is seldom required for drug delivery and substance exchanges. BBB permeability can be transiently increased by pulsing low frequency electromagnetic field [73]. In vivo, GMS 900 MHz whole-body exposure of rats for 2 h per day for 7 consecutive days (SAR up to 14 mW/kg) increases BBB permeability that lasts up to 14 days after treatment…
… It has been shown that pre- and post-natal exposure of rat embryos to commercial mobile phone RF induced an increase of neurodegeneration in Purkinje cells in the cerebellum of rats assessed during adulthood [76]…
Equally noteworthy is the effect of RF 900 MHz long-term application on juvenile rats [77] that appeared to be more susceptible to oxidative stress metabolism measured in peripheral investigated tissues and blood…
Melatonin is another important molecular player regulating brain physiology. Several groups investigated the disruptive effect of EMF on the production of the hormone melatonin by the CNS pineal gland, which controls the body’s circadian rhythms [79]…
… the impact of EMF exposure of newborn babies to EMF derived from nursing incubators cannot be overlooked [85].
We selected a few relevant examples on the investigation of how RF might impinge on everyday life of selected segments of the populations. In particular, a study that investigated mobile phone use in youngsters is quite alarming.
Conclusions
It is virtually impossible to account for all of the potential situations in which we encounter casual or expected EMF exposure in our daily life. Moreover, although regulated by physical and mathematic laws, it is quite tricky to describe the variable interactions between RF and biological systems.
One can envisage that EMF “speaks” to each organism and each cell with a different language. The answer to that call can potentially induce protein modification, ion exchanges and nucleic acid conformational changes that might cause positive, adaptive or destructive effects and the modulation of EMF can determine the benefit or the severity of the outcomes. Numerous works indicated that tuning the use of pulsating low and extremely high frequency (EMF) trains of stimulation might be used in cancer treatment [1] as well as in regenerative medicine [119,120] where cells can be induced to differentiate with minimal manipulation and without pharmacological treatment or gene modification [121]. One of the most exciting findings is that using the ion cyclotron resonance of different elements, i.e., calcium (7 Hz 9.2 micro Tesla), it is possible to induce neuronal differentiation, reducing the carcinogenic phenotype [122]. We foresee the possibility that this tuning can be achieved also with RF in the range of 900 MHz, as some positive reposts on memory enhancement would suggest.
It is therefore important that at least in research, the standardization of protocols, reproducibility of results and unbiased interpretation take place. We attempted an overview of the most recent advances in understanding the nature and the possible functional impact of the effects induced by RF exposure on living beings. We discussed the molecular path finding of the in vitro investigation as well as the functional complexity of in vivo experimental designs. The overwhelming amount of the sometimes contradictory incoming data about potential damage in humans has been briefly considered here as regulatory agency guidelines continuously monitor and regulate the issue.