Received Date: August 23, 2012; Accepted Date: September 20, 2012; Published Date: September 24, 2012
Citation: Al-Garawi ZS, Al-Fartusie FS, Al-Mandlawi HB, Al-Zaidi NK (2012) A Study Case on the Impact of Prolonged Exposure to Cell Phone Radiation, among Iraqi Students, on RBC- AChE Activity. Biochem Anal Biochem 1:116. doi: 10.4172/2161-1009.1000116
Copyright: © 2012 Al-Garawi ZS, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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The effects of moderate and extremely high exposure to radiofrequency electromagnetic radiation emitted from mobile phone on the activity of RBC-acetylcholinesterase (AChE) were investigated. AChE activity was measured using UV-Vis spectroscopy by Ellman modified method. The results demonstrated that the prolonged exposure (3-5 hrs) to electromagnetic radiation increased enzyme activity while the main inactivation took place in moderate exposure (1-2 hrs) among young male undergraduate students (18-25 year ages). In conclusion, according to the changes observed in the AChE activity, it is proposed that the increasing duration of electromagnetic radiation exposure causes an increase in cholinergic activity.
Mobile phone radiation; RBC-acetycholinestrase activity; Ellman method of AChE assay
RFR: Radiofrequency Electromagnetic Radiation; SAR: Specific Absorption rate; CNS: Central Nervous system, AChE: Acetylcholinesterase; ACh: Acetylcholine; RBC: Red Blood Cell; EMF: Electromagnetic Field
The increasing usage of telecommunication devices available by a large number of individuals (>109 worldwide and the number is increasing exponentially) and spending long time connected has aroused interest of possible interactions reflected on human body by radiofrequency electromagnetic radiation (RFR) . This form of energy (10 KHz-300 GHz in the electromagnetic spectrum), emitted from antenna of mobile telephones and cellular masts, can penetrate easily into organic tissues, absorbed and converted into heat, usually the familiar use of this energy is in cooking by the microwave ovens . It has been indicated that 80% of the radiation emitted by a cell phone is absorbed by the head of adult human beings.
There are many factors which affect the distribution of energy absorbed in an irradiated organism which are non-uniform, and also lead to the formation of so called ‘hot spots’ of concentrated energy in the tissue in a certain areas of the head. Chou and co-workers has been reported that two brain regions less than a millimeter apart can have more than two-folds differences in specific absorption rates (SARs) when different areas of rat brain was exposed to RFR for long time . The situation is more complicated if the animal is moving in a RF field. Depending on the amount of movement of the animal and duration of the exposure, the energy absorbed in its body could become either more complex and unpredictable or more uniform, it seems just like a microwave oven with a rotating carousel provides more uniform heating of the food than one without [4-6].
Several studies have indicated a possible effect of Electromagnetic fields (EMF) emitted from mobile phone on brain activity; including sleep , attention , learning and memory [9,10] and cognitive performance . On the other hand, it has been suggested that the brain harm from RFR of mobile phone might derive to modify electrophysiological activity in human brain  and to alter neurotransmission . These effects depend on amperage, frequency and exposure duration .
There is another study which shows that radiation from a mobile phone has disrupted the structure and biochemical characteristics of the most important enzyme in the central nervous system (CNS) acetylcholinesterase (AChE) especially between young people , the enzyme also known as acetyl hydrolase (E.C.184.108.40.206). It is a serine protease that found mainly in neuromuscular junctions and cholinergic brain synapses, in conducting tissue like: nerve and muscle, central and peripheral tissues, motor and sensory fibers [16,17] where its activity serves to terminate the signal transmission during neurotransmission process by hydrolyzing the neurotransmitter acetylcholine (ACh) when released from the nerve into the synaptic cleft relying the signal from the nerve [18,19].
The enzyme has also been detected in a large amount in human red blood cells (RBCs) [20,21]. Therefore, suppressed and/or increased AChE function in the peripheral and central nervous system (CNS) can be monitored by RBC-AChE as a biomarker .
On the basis of the foregoing contradictory conclusions, and in order to further clarifying if prolonged usage of the mobile phone is a healthy safe on the nervous system of human, experiments are underway by our laboratory to study the effect of long-time exposure of the mobile phone used by the chemistry department students on the activity of RBC-AChE.
All chemicals were purchased from Sigma Chemical Company.
Blood was collected under an approved Human Subject Protocol from healthy male student volunteers of Chemistry Department, College of Science, Al-Mustansyriah University. This case-control study was carried out on 90 young students between October 2011 and May 2012. The study group comprised 25 students who used the mobile about (1-2 hrs/day) 5 days per week continuously. The other 30 students used cell phone for prolonged time (5-8 hrs/day) continuously for 5 days/week. The rest 35 students were in normal sporadic use (10- 20 min daily). There ages ranged from 18-25 years and they had no history of Epilepsy or any neurological related diseases.
Blood was collected in EDTA tube and kept on ice. Within 4 hours of collection, the sample was centrifuged in a centrifuge at 3000 rpm for 15 min, and then RBCs were separated and stored at 4°C .
AChE activity was measured for RBCs using a modified colorimetric method developed by Ellman and co-workers  based on the following reactions:
The principle of the method depends on the measurement of the rate of thiocholine production when acetylthiocholine iodide is hydrolyzed by AChE. This is accomplished by the continuous reaction of the thiol with DTNB (Ellman reagent) to produce the yellow product (equations 1 and 2 above). The enzyme activities were
measured by following the increase in absorbance at 412 nm for 4 min intervals resulting from the formation of this color product. The general enzymatic reaction can be summarized in equations 3 and 4:
Where: Enz is the enzyme, AcCh is the substrate (ACh), and Ch and AcOH are the products (choline and acetic acid, respectively) .
The data are expressed as means ± SD (n), where n refers to the number of students. Statistical comparisons between the means of mild and prolonged exposure to EMR of mobile phone and those of normal usage were carried out by T-test using SPSS version 16. Significance was determined at p < 0.05. Pearson correlation coefficients (Twotailed) was used to correlate between time exposure and the enzyme activity, correlation is significant at the 0.05 level.
The enzyme activity of AChE clearly exhibits an important increased after mild to high usage of mobile phone continuously compared to that of normal speaking (5.02 ± 1.27 vs. 4.23 ± 1.27 mol/ min, p<0.02). According to Table 1, it appears clearly that the AChE rate is highly dependent on the usage time of the mobile phone. The data show that the average rate of the AChE increases with an increase in the time of exposure to the radiation of cell phones (r=0.25, p<0.05) indicating an enhancement in the hydrolysis of ACh iodide.
|Enzyme test||Normal exposure students||Mild to high Exposure students|
|Mean ± s (n)||p||%||Mean ± s(n)||p||%||r|
|AChE activity *10-15 Mol/min||4.23 ± 1.27(35)||0||45.7||5.02 ± 1.27(60)||0.001**||54.2|
|Time of exposure||14.2 min ± 1.22(35)||3.1hr ±1.3(60)||0.25*|
p*: significant, p** : very significant
Table 1: Results of RBC-AChE activity tests in different groups of students.
In order to consider the effect of different time consuming in mobile connection on changes of AChE activity, the present analysis described in Table 2 shows the clear significant increasing of the enzyme activity after 1.8 hr and 4.02 hr as a mean time regarding to that of normal exposure individuals (4.89 ± 1.04 and 5.11 ± 1.27 vs. 4.23 ± 1.27 respectively, p<0.001), never forget that this enhancement increasing linearly with time (r=0.46, p<0.05).
|Effect tests||Normal||Mild exposure students||High exposure students|
|Mean ± s(n)||%||Mean± s(n)||p||%||Mean ± s(n)||p||%||r|
|Age||21.45 ± 1.68(35)||33.03||22.32 ± 1.36(25)||0.01*||34.7||21.17 ± 2.5(35)||N.S||32.5|
|Time of exposure||14.2 min ± 1.22(35)||3.80||1.80 hr ± 0.4(25)||--||29.7||4.02hr ± 0.95(35)||--||66.4||0.46*|
|AChE activity *10-15 Mol/min||4.23 ± 1.27(35)||29.7||4.89 ±1.04(25)||0.003**||34.3||5.11 ± 1.27(35)||0.0001***||35.9|
p*: significant, p** : very significant, p*** : highly significant, N.S: no significance
Table 2: Frequency of RBC-AChE activity in relation to a history of students’ duration exposure.
The most important issue of mobile phone usage is the exposure duration while the mobile phone is in the near field and localized at the head region, whatever, this exposure has been proved as a non-thermal in nature [26-28].
In this study, we carried out three experiments. First: with normal speaking emission (10-20 min daily), second: with moderate speaking emission (1-2 hrs/day continuously), and the third group was with highly speaking emission (3-5 hrs/day continuously). The exposure in these cases is simulating the situation of listening and talking by users through mobile phone during connection. Results are listed in Tables 1 and 2 which express a high rate of AChE as the user being closed with the cell phone at length.
The results in this study strongly suggested that the RFR action causes a rise in the enzyme rate when RFR exposure for long time. Similar results have been reported previously, where it was observed that the RFR affects and enhances AChE activity in nervous systemderived cells in culture . In the case of RFR-induced changes in cholinergic activity in the brain, another previous study demonstrated that there is an increase in cholinergic activity in the hippocampus in rat after the session of sham exposure and therefore there is well deterioration in functions of cells .
In the framework of the importance of AChE modifications induced by the RFR comparatively to the physiological one, it has been shown that this modification is in the same order that observed with the attained patients of the Alzheimer’s disease , where there is a decline in ACh, therefore, the principal medicines, are suppressants of AChE in order to compensate for this decrease of the neurotransmitter. This result is therefore in agreement with the suggestion of recent study which showed that the EMF radiation directly affects neurons by reducing the neuronal reactivity, increasing the neural membrane conductivity and prolonging their refractory period .
It is important to mention here that there is an indication from literature which depicts that the prolonged exposure to radiation emitted causes an effect on the brains of younger human faster than older by speeding up the brain response time, and that is really the slowest process of modifying the normal brain stability which is lead to create senility .
Furthermore and in comparison with other studies, like studies of Barteri and co-workers on solution of electric eel, and Vukova and co-workers on frog skeletal muscles, the results in the present work did not confirm such an effecting of RFR [15,27]. They had found, in contrary with our results, diminution in enzyme activity accompanied by a change in its biochemical characteristics. More recently, the same decrease in AChE activity has been recorded with changes observed in the secondary and tertiary structure of the enzyme. These changes in enzyme structure would limit the binding of substrate to the enzyme active site leading to inactivation of the enzyme . Also, a significant decrease in acetylcholine esterase activity was found in exposed rats for long term (3 hrs/day) of RFR, but under short-term exposure, the results showed that there is not any significant effect on AChE activity .
In fact, the observed contrasts between different studies are expected since no similar conditions have ever been applied between different studies, and also could be attributed to different sources of enzyme used. Moreover, there is an insight provided, depending upon the sea of information liberated from extensive research on acetylcholinesterase in vertebrates and invertebrates, refers that the effect on vertebrate, especially in mammalian CNS, is more complicated than on invertebrate depending on the fact that the invertebrate AChE is not a typical vertebrate enzyme, but exhibits properties (kinetics and sequence analysis) intermediate to that of vertebrate AChE. This is particularly based on comparing the structure of ChE in vertebrate and invertebrate . Such changes in AChE activity are also not identical between animals and humans; most previous toxicology studies failed to detect any significant effect of phone radiation on animal health, but this does not prove that humans are safe and that the current safety standards protect all users.
The present work was supported by a research plan from Chemistry department, AL-Mustasyriah University.