Effect of Electromagnetic Waves of Mobile Phone on Human Brain Effect of Electromagnetic Waves of Mobile Phone on Human Brain

Mobile phones (MP) have become one of the most used devices for communication. Historically, enough proofs have ruled out the substantial short-term effect of radiofrequency electromagnetic field (RF-EMF) emitted by MP on the human brain and its cognitive performance. The aim of this mini-review is to examine the different effects of electromagnetic waves emitted by MP on human brain. We base our arguments on analyzing recent neuroimaging and electroencephalography studies that will elaborate the effects of the human brain's exposure to the EMF’MP. Several studies indicated an increase in cortical excitability and/or efficiency related to EMF exposure, while other experiments proved that no changes or variations have been found after EMF exposure. Based on a study done in 2020, the exposure to EMF emitted by MP has no abnormal discharges during the real MPR exposure. In contrast, an increase events number in real exposure has been found.


INTRODUCTION
Mobile phones (MP) have become the most important tool of communication in daily human life due to their countless perks that simplify our lives, even with the possible risks that have been expressed about them.In 2014, there is an estimated 6.9 billion subscriptions globally (1).The MP transmit and receive microwaves radiations at specific frequencies, also they are often used in proximity to the human head, and that makes the human brain exposed to a high-specific absorption rate of radiofrequency electromagnetic fields (RF-EMF) (2).Those waves can be classified into two classes, based on the capability of ionizing atoms and breaking chemical bonds: ionizing and non-ionizing waves (3).MP emit nonionizing radio-waves with low frequency which vary between 800 and 2200 MHz, and that is too low for breaking bonds or to cause ionization of atoms and molecules.In contrast, for long-term, the exposure to EMF should be taken seriously (3).In 2011, the world health organization's international agency for research on cancer announced that the usage of MP for 30 minutes or more per day could increase risks of brain tumor caused by EMR.
The biological effect of EMF can be divided into thermal; like microwave mechanism; and non-thermal.Thermal effects are associated to local heat production.Nonthermal effects are caused by energy absorption, which is not associated with temperature change but with some other changes produced in the tissues (4).Radiation emitted by MP could change intracellular signaling pathways by change in Ca 2+ permeability across cell membranes and level of calcium in cells (4).In addition, the absorption of EMF by tissues increases their temperature and leads to serious risks on human health.Some experimental studies show the thermal effects of EMF such as vascular occlusion and tumors in the brain (5).Headache, blood pressure, heartbeat, other warning signs and an increase body temperature are presumed to be due to EMF exposure (5).The possible physical and biological effects of MP on the human health lead to the analysis of their effects in details (6).The main objective of this mini-review is to shed light on different effects of EMR emitted by MP on the human brain.

RESEARCH METHODOLOGY
The data used in this mini review were mainly from PubMed and EBSCOhost (from 2010 to March 2020).Research was based on a set of keywords related to (electromagnetic fields, mobile phones, brain, mobile phone radiations, human brain), followed by screening titles and abstracts.The selected articles were grouped into articles related the effect of EMR emitted by MP on the human health, and the effect of electromagnetic waves of MP on the human brain.Articles were selected conforming to eligibility criteria:  Articles assessed the effect of electromagnetic radiation and written in English;  Articles studied the impact of EMF on human health;  Articles evaluated the impact of MP;  Articles presented clearly information on MP related to the human brain. 20 participants (13 males and 7 females) generic MP with conductivity for 835MHz is 47.94 and 0.80 (S/m), and for 1900MHz is 45.44 and 1.27 (S/m).variation in the averaged SAR among the head could reach up inside the brain.

2015
Effect of exposure and withdrawal of 900-MHzelectromagnetic waves on brain, kidney and liver oxidative stress and some biochemical parameters in male rats (Ragy) (4).
study the effects of exposure to MP emits 900-MHz EMR on the brain, liver and kidney of male albino rats  30 male adult albinos rats (10 rats for each group);  16 to 18 weeks old;  170 to 200g.
3 groups of albinos in the experiment; Control group with ordinary rat diet; Exposure group: were exposed to 900-MHz for 1 h/day for 60 days using the experimental phone exposure device; Withdrawal group: were exposed 1 h/day for 60 days to 900-MHz then left for 30 days without exposure.
A significant increase in malondialdehyde levels in exposure group in comparing with the other groups.Significant decrease in exposed group of total antioxidant capacity levels in brain, liver and kidney tissue.
(18)iwal and Pattnaik 2019) has detected some variations in the power of the brain waves.The results of (Roggeveen and al. 2015; Pattnaik, Dhaliwal, and Pattnaik 2019) proved that the EMR has an effect on the human brain.First study (Ragy 2015) linked to the exposure to 900 MHz exhibited a significant decrease of an exposed group in total antioxidant capacity levels in brain, liver and kidney tissue.On other hand, (Selmaoui and al. 2018) have demonstrated no changes within the group of volunteers associated with the exposure to GSM radiofrequency.The results of an experiment realized by (Volkow and al. 2011) indicated that an exposure of 50 min was associated with increased brain glucose metabolism in the region closest to the antenna.The finding concords with the study conducted by (Forouharmajd, Pourabdian, and Ebrahimi 2018) which proclaims that the EMFs emitted by MP were increases brain tissue temperature and the effect cumulates on the tissue.The study of the effect of prolonged use of MP on brainstem auditory evoked potentials (Gupta et al.) showed no significant difference in latencies, inter-peak latencies and amplitudes of ABR wave.On other side (Roggeveen, van Os and Lousberg 2015) showed in their experiment that MP radiation induced event related potentials with peak latency 240-500 ms post-stimulus.Study of (Buckus and al. 2016) exhibits that stronger power, higher SAR and lower frequency of MP is associated with stronger electric force of MP, which means that most of the electric fields are absorbed at the side of the head nearest to the MP.In the same context, an experiment (Adibzadeh and al. 2015) has indicated a variation in the averaged SAR among head regions that could reach inside the brain.Nevertheless, there are apparent inconsistencies between studies that limit conclusive statements in brain areas.This lack of consistency may partly be due to methodological factors, such as differences in signal type, exposure frequency, exposure intensity, age of volunteers, temperature of the brain tissue and exposure duration.Moreover, interference between radio frequencies emitted by MP and EEG signals recorded during exposure, and the history of EMFs earlier to the study, are not always controlled.The Objective of this mini-review was to disclose the effects of MP EMF exposure on the human brain.The presented studies included our review state, in general, that "there is no evidence for any short-term effects of EMFs emitted by MP on human cognitive performance"(17).ahighpriority research area, as they are exposed to a longer period of MP(18).Before further clarifications of the cause and effect relationship for MPs, it is considered safer to reduce MP usage.It has been proposed to reduce the potential damage caused by MPs by restricting the length of the call, or by using hands free (15)experiment of modelling and assessment of the electric field strength caused by MP to the human head (Buckus and al. 2016) proves that stronger power, higher SAR and lower frequency of MP are associated with stronger electric forces of MP depending on the effects of the electric power of the device.DISCUSSIONThis current mini-review questions the effect of EMR of MP on the human brain.Electroencephalogram (EEG) is a non-surgical measure of the electrical activity of the brain(16).As a dependent variable, EEG was deliberate because the functioning of brain tissue is based on electrochemical processes(12).Five from 13 studies have examined the exposure effect of EMFs on EEGs of participants.Three studies showed no significant effects or no abnormal discharges during the exposure (Trunk and al. 2013; Zentai and al. 2015; Azmy and al. s. d.); although (Roggeveen and al. 2015) have revealed the effect which was stronger when the MP was placed on the ear and increased the power of several frequency bands (alpha, beta and gamma).Other experiment conducted by (Pattnaik, We can justify the effects of MP EMF exposure on the human brain and its function according to the latest study to date(15)which proved that there were no abnormal discharges during the real MPR exposure, but an increase in the number of events in real exposure has been found.The World Health Organization (WHO) has identified the potential health effects of MP EMF exposure on children and adolescents as EMFs Effect of MP on human brain Health Sci.2020;1:6p

Table 1 :
Summary of studies analyzed the effect of EM radiation on human brain.