Essay: Effect of Radiations Associated With Cellular Phones on Human Health

Abstract – this paper reviews scientific studies conducted to determine possible human health issues caused by radiations associated with cellular phones. A cellular phone generates radio-frequency (RF) radiation in order to communicate. The human head is often exposed to this radiation. This exposure causes the human body to absorb a certain amount of energy quantified by the Specific Absorption Rate (SAR). Various research have been done to identify the biological risks caused by this exposure; the yielded results are classified into three major categories; the positive effects, the negative effects and the no effects. Scientific tests and evidences published in support of each category are analysed and discussed.
Keywords – Cellular phone, Radio-frequency radiation, Specific Absorption Radiation
I. INTRODUCTION
Cellular phones are slowly becoming indispensable tools to human civilization. According to recently published statistics and forecast, the number of mobile phone users worldwide is predicted to reach 4.77 billion in 2017; this number will rise to 5.07 billion by 2019 [1]. In order to establish communication, cellular phones produce radio frequency (RF) electromagnetic radiation in the range of 800 MHz to 2200 MHz [2]. Radio frequency radiation occupies the frequency range of 3 kHz to 300 GHz in the electromagnetic spectrum. RF is known to be non-ionizing radiation due to its low energy generation, inadequate to break chemical bonds [3]. Other known sources of RF radiation are wireless devices and sensors installed in smart meters, security monitors, and various types of controllers in homes, offices, factories, health care facilities, gyms and sport arenas. RF electromagnetic radiation is the backbone of wireless technology [4].
There has been growing concern regarding the frequent exposure of human tissues to RF radiation and the possible resulting biological effects. Scientific research on this topic date as back as the 1940s. These were followed by the publication of guidelines to limit the exposure to RF electromagnetic radiation in the 1960s, with the objective of providing protection against the then known adverse health effects [4]. It is estimated that about 50% of radiated energy is absorbed by human tissues in the head when the RF radiation is emitted from a cellular phone held next to the human head [3]. The rate at which the amount of energy is absorbed is quantified in term of the Specific Absorption Rate (SAR), which is expressed in watts per kilogram (W/kg). The whole-body average (WBA) SAR limit set by IEEE to provide suitable protection is 0.4 W/kg for occupational exposure and 0.08 W/kg for public exposure [5][6].
Numerous studies done on the effects caused by the exposure of human tissues to RF electromagnetic radiation have yielded different results, which have caused divisions in the scientific community. While some research have indicated positive biological effects such as improve bone repair, wound healing and other various therapeutic applications [5-9], many have indicated negative effects such as cancer, blood brain barrier (BBB) permeability function, DNA damage, and immunity system function [10 – 21], even though there has not been strong scientific evidences linking these diseases to RF radiation exposure. There are also studies that have shown minimal to no effect caused by RF radiation exposure.
The purpose of this paper is to review the numerous studies done on the biological effects caused by exposure to RF radiation, as identified in the paragraph above. The structure of this paper is as follow: positive effects are discussed in section II, followed by the negative effect in section III and the no effect in section IV. A conclusion is done in section V and a list of reference is given at the end of the paper in section VII.
II. POSITIVE EFFECTS
Numerous research showing positive effects of human exposure to RF radiation has been done. In the medical domain for instance, RF technologies are vastly used, from treatment of cancer to wound healing and bone repair [7]. The literature by Gandhi [8] highlights ongoing research about the beneficial application of RF electromagnetic technology in the treatment of Hyperthermia and several other medical practices. In this section, major studies and applications focusing on positive effects of RF radiation exposure will be summarized
A. Radiofrequency ablation
Radiofrequency ablation (RFA) is a technique used to destroy cancerous cells by raising the internal temperature of tumour tissues, thereby killing tumour cells and achieving therapeutic purpose [9]. The study done by Chadwick et al. [10] suggest that RFA technique is very effective in the treatment of dysplastic Barrett’s esophagus (BE) and in preventing the progression of the disease, while minimizing the rate of known adverse events. In this study, patients diagnosed with BE with high-grade dysplasia or intramucosal cancer were divided into two groups, with one group subjected to complete Endoscopic Mucosal Resection (EMR) treatment while the other group was treated with RFA. The study found that in the short term treatment of dysplastic BE, RFA is as effective as complete EMR but advert event rates were higher with complete EMR. This has led to RFA replacing earlier ablative treatment in the management of dysplastic BE.
B. Pulsed Electromagnetic Fields
Pulsed Electromagnetic Fields (PEMF) techniques have been used extensively in the treatment of damaged bones and wound healing [11]. PEMF technique consist of exposing the human body or an animal to low frequency low energy pulsed electromagnetic field. According to a number of studies, this results in pain reduction, muscles relaxation, and acceleration of bone repair and wound healing. Studies by Satter et al. [12], for example, suggest successful PEMF treatment to enhanced bone healing. In this study, 19 patients diagnosed with non-union or delayed union of long bones were exposed to low amplitude PEMF, with pulse width of 0.3 mSec, frequency of about 80 Hz and pick magnitude field of the order of 0.01 to 0.1 mT. 11 out of the 13 patients who completed the treatment period of 14 weeks had successful bone healing. Also the literature study by J van Nguyen and R Marks [13] indicates positive result of PEFM application in the treatment of osteo-arthritis.
C. Extremely low frequency electromagnetic fields
A preliminary study by Iorio et al. [14] has reported an increase in the mobility of spermatozoa exposed to extremely low frequency electromagnetic fields (ELF-EMF), depending on the field characteristics. In this study, semen samples were exposed to a square waveform ELF-EMF of amplitude 5 mT and frequency of 50 Hz. Significant increase in the mobility of spermatozoa were observed. In [15], Yoo-Jung et al. identified possible application of ELF-EMF in regenerative medicine. In this research, grapheme-based substrates were exposed to ELF-EMF of 50 Hz, 1mT. This led to a stimulation of neuronal differentiation of human mesenchymal stem cells (hMSCs)
D. Effects on human sleep
A study by Borbely et al. [16] reported that pulse high frequency EMF in the range of radiotelephone has an impact in the sleep pattern. The study consisted of recording two sessions of nocturnal sleep (sleep episode: 23.00 – 07.00 h) of 24 healthy young men. In one session, labelled “field exposure night”, the subjects were exposed to a pseudo GSM signal of 900 MHz while in the other session, labelled “sham exposure night”, subjects were not exposed to the signal. A reduction in the amount of waking after sleep onset (WASO) from 18 to 12 min and an increase in the spectral power of electroencephalogram (EEG) in non-rapid eye movement (NREM) sleep were observed. Further research done by Loughran et al. [17] indicated that exposure to mobile phone prior to sleep may improve rapid eye movement (REM) and alter the sleep EEG in the first NREM sleep.
E. Effects on cognitive functions
Various studies have reported that exposure to RF radiation from cellular phone may affect cognitive functions in humans. Early research by Hladky et al. [18] to monitor attention and memory function found that the mobile-emitted EMF did not affect mental function. Preece et al. [19] performed further investigation, exposing 36 subjects to a simulated mobile telephone signal of 915 MHz and found little to no evidence linking RF radiation to any cognitive function. In another study by Koivisto et al [20], 48 healthy subjects performed a set of 12 reaction time tasks, twice by each participant in a counterbalanced order: one with and one without exposure to 902 MHz GSM signal. An increase in response time in simple reaction time and vigilance task and a decrease in cognitive time needed to perform mental arithmetic tasks were observed during the exposure. The results suggested that the exposure to RF radiation from cellular phones may have facilitating effects on brain functioning, especially in tasks needing attention and manipulation of information in working memory. But in another recent study by the same group, these results could not be replicated [21]. The research by Lee et al. [22] focusing on human attention, suggested that after exposure to RF radiation, the attentional functions may be differentially enhanced.
III. NEGATIVE EFFECTS
Even though RF are classified as non-ionizing radiation, they can still cause thermal effect in human bodies. Exposing organic compounds to large amount of RF radiation results in heat, generated by the vibration of molecules; this is the principle of operation of microwave ovens. This resulting heat can cause damage to human tissues which could result in health issues. A majority of studies have reported possible carcinogenic effects. This section summarizes selected leading studies and literatures done on possible negative effects on human health caused by exposure to RF radiations.
A. Cytogenetic effects
The study by Blank and Reba [23] reported the possibility of changes in DNA molecule, cause by the effect of high frequency radiation emitted from cellular phones on charges moving on the DNA structure. In this research, the magnetic field exposure and heat shock on specific protein-DNA binding were studied in four human cell lines. It was found that there was interaction between magnetic fields and conducting electrons existing in the stacked bases of the DNA. Further research [24]-[25] have suggested that depending on the generated energy level, exposure to RF radiation can cause breaks in the DNA stands.
B. Carcinogenic effects
Carcinogenic effects have the biggest amount of research and publications done on this topic. Until now, these research have yet to produce substantial scientific results to validate the induction of cancer caused by RF radiation exposure. The Fact sheet No 193 published by the World Health Organization (WHO) [26] stated that there was no been enough credible evidence linking RF exposure to brain tumours or any sort of cancer. The International Agency for Research on Cancer (IARC) has classified RF electromagnetic fields as possibly carcinogenic to human, based on some shortcomings and inconsistent evidence from studies. In 2001, a study by Inskip et al. [27] finds little to no evidence of an increased risk of glioma, meningioma, or acoustic neuroma related to the use of cellular mobile phones. Further research by Lönn et al. [28] reported an increased risk of acoustic neuroma associated with mobile phone use of at least 10 years duration. A recent study by Hardell et al. [29] also reported a consistent pattern of increased risk for glioma and acoustic neuroma associated with use of cellular mobile phones.
C. Effects on hearing
Ozturan et al. [30] investigated the effects that could be caused by cellular phone RF electromagnetic field. Thirty volunteers with normal hearing took part in the research. The research consisted of measuring stimulated otoacoustic emissions (OAE) of subjects before and after they have been exposed to mobile phone EMF for 10 min.. The results concluded that no effect on hearing from exposure to RF radiation. However the study by M. Faruk and S. Dasdag [31] reported that a higher degree of hearing loss was related to prolonged exposure to RF electromagnetic field emitted by cellular phones. The study was done on three groups, with two groups made of 20 men each, who have used cellular phones for different periods and a third group made of 20 men who have never used a cellular phone. A pure tone audiometric test (PTA) showed higher frequency detection threshold found in subjects who talked approximately 2h per day on cell phones compared to other subjects.
D. Effects on Blood Brain Barrier (BBB)
Early studies by Salford et al. [32] reported that BBB could be significantly opened at energies below the thermal level of continuous RF exposure. During this investigation, male and female Fischer 344 rats were exposed in a transverse electromagnetic transmission line chamber to continuous waves of 915 MHz, and to pulse modulated waves with repetition rates of 8, 16, 50, and 200 s-1. The SAR was changed between 0.016 and 5 W/kg. The outcome showed that both the continuous and pulse-modulated waves have the potential to open the BBB for albumin passage. A further study to investigate the possible effects of pulse modulated 900 MHz and 1800 MHz RF radiation on the permeability of BBB of rats was done recently [33]. The study found a possible increase of the permeability of BBB
IV. NO EFFECT
At present, all studies done on the impact of RF electromagnetic radiation emitted by cellular phones exposure to human health have reveal few to no consistent effects. Most of the effects that were observed during studies have appear to be within the limits of normal biological variation, hence unlikely to have any health consequences [34]. A research by Thomas et al. [35] investigating human exposure to mobile phone frequencies found no significant association between the exposure and chronic symptoms or between the exposure and acute symptoms.
V. CONCLUSION
From the available studies and literatures, it can be seen that the scientific community is divided about the possible effects of radio-frequency radiation, such as those emitted by cellular phones, on human health. None of the research on detrimental effects such as cytogenetic or carcinogenetic have produce strong and consistent scientific evidence to be associated to RF radiation. However it is still recommended that excessive unnecessary exposure should be avoided, and measures must be taken to reduce personal exposure. International organizations such as the IEEE and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) have developed standards and safety guidelines for exposure to RF radiation. It is believed that further research must be conducted to address potential long term effects of mobile phone use.