|Year : 2021 | Volume
| Issue : 2 | Page : 168-173
Impact of mobile phone radiation on salivary gland: A systematic review
MP Revanth, S Aparna, Parangimalai Diwakar Madankumar
Department of Public Health Dentistry, Ragas Dental College and Hospital, Chennai, Tamil Nadu, India
|Date of Submission||07-Feb-2021|
|Date of Acceptance||04-Mar-2021|
|Date of Web Publication||22-Jun-2021|
M P Revanth
Department of Public Health Dentistry, Ragas Dental College and Hospital, 2/102, East Coast Road, Uthandi, Chennai - 600 119, Tamil Nadu
Source of Support: None, Conflict of Interest: None
In the recent decades, the use of mobile phone has increased drastically. This has raised many concerns about the potential health risk to the individuals who are exposed to mobile phone emitted radiation. The aim of this systematic review is to find out the impact of mobile phone emitted radiations on salivary gland. An electronic database search was performed to identify the suitable literature using Cochrane, EBSCO host, PubMed, Google Scholar, and Trip database. The literary search was focused on the impact of mobile phone emitted radiation on the salivary gland. Based on inclusion and exclusion criteria, the studies were selected. A total of 31 relevant studies were identified, and 11 articles were taken for the systematic review. The studies concluded that the radiations emitted by the mobile phones have detrimental effects on salivary gland.
Keywords: Mobile phone, nonionizing radiation, salivary gland
|How to cite this article:|
Revanth M P, Aparna S, Madankumar PD. Impact of mobile phone radiation on salivary gland: A systematic review. J Oral Res Rev 2021;13:168-73
|How to cite this URL:|
Revanth M P, Aparna S, Madankumar PD. Impact of mobile phone radiation on salivary gland: A systematic review. J Oral Res Rev [serial online] 2021 [cited 2021 Aug 5];13:168-73. Available from: https://www.jorr.org/text.asp?2021/13/2/168/319003
| Introduction|| |
The rapid emergence of mobile technology caused enormous changes in day to day lifestyle of individuals. Mobile phones are the most efficient and convenient way of hand held communication tool which is considered to be the most important form of wireless communication which is essential for work and social life in the emerging fast-paced modern society. It has been predicted that the average annual growth rate of 1.9% of mobile phone users will increase between the time span of 2018 and 2025, where the mobile subscribers will reach to 5.8 billion counting 71% of the world population.
The mobile phone users are often exposed to ultra-high frequency of nonionizing exposure of electromagnetic radiation (EMR) ranges between 300 and 3000MHz. There are two possible ways which could affect the health of the mobile phone users, firstly due to the thermal effects caused by the increase of temperature of nearby tissues during prolonged conversations, second due the consequences of nonthermal effects from the base station and phones itself. In 2012, the International Agency for Research on Cancer categorized the radiofrequency electromagnetic radiation as possibly carcinogenic to humans and classified it as Group 2B agent.
EMR from the mobile phones is localized. The considerable biological side effect is due to continuous exposure and energy absorption by the human body mostly the head and neck regions which are closely associated during the usage. These exposures not only affect the phone user but also the neighbors residing in the close proximity to the base station.
A study conducted by Hardell et al. indicated an association between mobile phone usage and brain tumor. He also stated that prolonged use of cell phone (>10 years) added to the risk of brain tumor and most commonly in children. Few other studies show the increased incidence of meningioma and gliomas in mobile phone users than in nonmobile phone users.
Salivary gland is an organ which is in close proximity to the mobile phone during usage and parotid gland is the major field of interest. Various studies suggested the incidence of salivary gland dysfunction distinctly increases in the population who majorly use mobile phone for a longer period of time. Contrary to this, various other studies stated no significant association exist between salivary gland disorder and mobile phone radiation exposure.,
Effects of radiation on the salivary gland and its components gain a particular interest, as the altered salivary composition cause irreversible complications, namely increase risk to oral infections, oral discomfort, and increased susceptibility to dental caries due to oral dryness and distress. The parotid gland receives the major attention as it is located under the skin of the face near to front of the ear. The parotid is more commonly affected by the heat and harmful radiation emitted by the mobile phone during its utilization as it was in direct contact with the mobile devices.
Hence, this systematic review was done to find out the effect of nonionizing radiation emitted by the mobile phone on the salivary gland especially parotid, as this salivary gland is close proximity during mobile phone use.
| Materials and Methods|| |
This systematic review utilized the methods as per the PRISMA (Preferred Reporting Items for Systematic Reviews and MetaAnalysis) Guidelines, to identify, evaluate, and summarize all relevant research findings. The protocol for systematic review was registered first with PROSPERO (Acknowledgement ID-210723).
The PECO analysis of the articles searched was:
- Population: High talk-time mobile phone users
- Exposure: Electromagnetic radiation
- Comparison: Low talk-time mobile phone users
- Outcome: Parotid gland changes.
Inclusion and exclusion criteria
- Studies which included the effects of mobile radiation on salivary gland
- Studies which had assessed the salivary gland changes including the change in salivary gland volume and salivary flow rate were included
- Cross sectional, case-control, cohort, and comparative studies were only included
- Studies done in the past 15 years were included. Since the usage increased drastically in the recent decades
- Studies which was written in the English language were only included.
- Studies that included other than salivary gland changes due to mobile radiation
- Qualitative studies, reviews, expert opinion, systematic reviews, meta-analysis, and case studies/series
- Studies that required translation to the English language.
Literature search strategy
The studies published from 2005 to 2020 were reviewed for literary consideration using the following database such as PubMed, Trip database, Cochrane, Google Scholar, EBSCO host. Boolean search operators “AND” and “OR” were used to link the search terms. The following search strategy was adopted: mobile phone, nonionizing radiation and salivary gland, mobile phone and salivary gland, nonionizing radiation and salivary gland, mobile radiation, and salivary gland. Hand searches of the articles were conducted to ensure additional relevant references but no relevancy had been found.
The data from the studies eligible for the review was extracted manually. It included the variables such as: first author name, year of publication, type of study design, aim, summary and outcome [Table 1].
Risk of bias assessment
The bias assessment of the studies included in the systematic review was done by using Modified Newcastle–Ottawa Scale. The ranking of the studies was given by assigning stars (*) based on the three domains, namely selection, comparability, and outcome. More the stars less the risk of bias. For our convenience, the stars are converted into alphabets. The scores are interpreted as poor (0–4*), fair (5–6*), or good (7–9*). The results of the assessment are displayed in this article [Table 2].
A total of 31 articles were obtained based on the title from different electronic database, namely PUBMED, TRIPDATABASE, EBSCO, GOOGLE SCHOLAR, and COCHRANE. PUBMED produced 12 articles, 2 articles obtained from TRIPDATABASE, EBSCO produced 1 article, Google Scholar produced 16 articles, and no articles were found in COCHRANE. The full texts of 23 articles were taken for further steps. Among the obtained articles, eight articles were eliminated due to duplication, seven articles eliminated after abstract reading, and three articles eliminated after full-text reading. Finally, on the basis of inclusion and exclusion criteria, 11 articles were selected for the review using PRISMA flowchart [Flow Chart 1].
The studies taken for this review identified the association of mobile phone use and its effect on the salivary gland in terms of risk of parotid gland tumor, changes in physiological, structural, functional, volumetric parameters of salivary gland and flowrate, and composition of saliva as well.
Studies done by Goldwein and Aframian 2010, Bhargava et al. 2012, Hamzany et al. 2013, Abu Khadra et al. 2014, Hashemipour et al. 2014, Aydogan et al. 2015, Siqueira et al., 2016, Singh et al., 2016, Ghoneim et al. 2016, Ranjitha et al. 2017 showed a difference in salivary flow rate, volumetric, and histopathologic changes of the salivary gland, alteration in protein concentration, and composition of the saliva after exposing to mobile phone radiation.
Whereas the studies by Lonn et al. 2006, Duan et al. 2011, and Söderqvist et al. 2012 showed no relationship between salivary gland tumor and mobile phone radiation exposure.
| Discussion|| |
Mobile phones receive and transmit radiation at the frequency range between 300 and 3000 MHz. When the human tissues are exposed to radiofrequency electromagnetic waves, the human tissue will absorb some amount of radiation which is called specific absorption rate (SAR), and it is expressed in watts per kilogram (W/kg). The radiation emitted by the mobile phone is one such harmful radiation that was absorbed by the human body and the rate of absorption will differ for the different parts of the body. For instance, studies have reported that about 40% of radiation emitted from the mobile phones were absorbed by head and hand since they were in contact while using the phone.
The prolonged use of mobile phone and its close proximity to the body have raised questions about its possible detrimental effects to the tissues that were near to it during the usage. This indeed gain importance in the assessment of salivary gland and its fluid after EMR exposure and makes it possibly a potential area of research. Meanwhile, saliva secreted from the salivary gland is one of the biological fluid which represents the various forms of biomarker that were secreted by the human tissues on exposing to hazards.
The largest salivary gland of the human body is the parotid gland which is located beneath the skin of the face and the near the front of the ear, its anatomy, continuous and constant contact, with the mobile phone emitted radiation for a longer period of time makes this gland a more vulnerable organ for heat and microwave energies.
In regard to the potential adverse outcome and its effects on the physiologic, structural, functional and carcinogenicity, various contradicting literature do exists, stating two different outcomes. Few studies suggest and state the association exists between mobile phone use and its adverse effects such as auditory canal pathology, migraines, headache, brain tumors, and physiologic changes in the salivary glands. On the other hand, few studies deny the above statement.
Growing health hazard on one hand and safety concern on the other creates awareness in the use of wireless equipment's and its concerns in regard to the possible health hazard caused by the electromagnetic radiation on the human body.
Various other studies conducted on the animal model by Aydogan et al. in 2015 and Ghoneim and Arafat EA et al. in 2016 observed numerous changes in histopathological sections of parotid glands of rats., In contrary, human studies done by Hardell L et al., in 2004 Lonn et al., in 2006, Duan et al., in 2011., and Söderqvist et al. in 2012 disproved the hypothesis.,,,
A study done by Sadetzki et al. found to have an association between parotid tumors and prolonged mobile phone use. Siqueira et al. study on cytokine expression profile among the mobile phone users shows elevated interleukin-10 level in ipsilateral parotid in comparison to contralateral parotids in participants using mobile phone users above 10 years. This change in salivary cytokine profile may be due to heating effects of nonionizing radiation.
Hamzany et al. in 2013 assessed the salivary secretion and its components, flow rate, and oxidative stress between the mobile and nonmobile phone users. The study result showed increase in the oxidative stress-related indices wherein decrease in flow rate, total albumin, and amylase activity in mobile users. However, in contrary, Khalil et al. found that there is no change in the parotid salivary profile such as protein concentration, oxidant, and antioxidant levels in the population who continuously exposed to the mobile phone radiations.
Bhargava et al., Hashemipour et al., and Goldwein and Aframian described that there was a raise in the temperature of the adjacent tissues in direct contact to that of mobile phones due to continuous and prolonged use, the study concluded stating long-term use of mobile phones increases the blood flow in accordance with the salivary flow and also the volume of parotid gland.,,
The main reason for the increase in the perfusion and flow rate of the saliva is consider due to the heavy heat exposure transmitted from the mobile phone to the underlying tissues, in turn leads to the increased capillary blood flow affects the parotid gland that is situated adjacent to it. Another reason for the increased flow rate is an increased parasympathetic tone and reduced sympathetic tone. A study conducted in 2017 by Ranjitha et al. also found the increase in salivary flow. However, a study by Singh et al. gives a different statement and proves lesser salivary secretion in majority of participants.
Among the 11 studies taken for review, salivary gland changes were found to be highest in the parotid gland in the aspect of salivary flow rate and composition and a positive relation was seen between the radiations emitted by the mobile phone in majority of studies.
| Conclusion|| |
In conclusion, the results of most of the studies found that the radiation emitted by mobile phones will have adverse effect on the salivary gland. However, few studies have apparently contradict the above statement. However, uncertainties do remain and a continued precautionary approach is recommended, until the situation is clarified. Further human and epidemiological studies are required to evaluate the long-term effect of mobile phone on the health of the individual.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]