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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 4  |  Page : 254-258

Influence of Handheld Mobiles on Parotid: A Cohort Study


1 Department of Oral Medicine and Radiology, Rajas Dental College and Hospital, Kavalkinaru, Tamil Nadu, India
2 Department of Oral Medicine and Radiology, Rajah Muthiah Dental College and Hospital, Kothangudi, Tamil Nadu, India

Date of Submission04-Sep-2017
Date of Acceptance08-Nov-2017
Date of Web Publication15-Feb-2018

Correspondence Address:
Gracelin E Ranjitha
Department of Oral Medicine and Radiology, Rajas Dental College and Hospital, Kavalkinaru, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_82_17

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   Abstract 


Introduction: Mobile phones generate heat and radiofrequency radiation. The parotid gland is one potential target, because mobile phones are pressed against the side of the face where the gland is located. Aims and Objectives: To compare the effect of mobile phone radiation on parotid gland volume, systolic velocity, salivary flow rate, and protein concentration between the dominant and the nondominant side of mobile phone usage among heavy mobile phone users. Materials and Methods: Ultrasonography of the superior lobe of parotid was performed bilaterally to measure gland volume. Systolic velocity of the external carotid artery in gland was calculated bilaterally using color Doppler imaging. Saliva flow rate was measured bilaterally with modified Schrimer strip. Carlson-Crittenden device was used to collect 0.5 ml saliva sample from the duct and biuret assay was done to determine the protein concentration. Settings and Design: A cohort study was conducted with 50 undergraduate students of a dental college based on the inclusion and exclusion criteria. Statistical Analysis Used: Pearson correlation test was used to correlate and compare changes in the parameters of parotid gland and analyzed to a significant level of 0.05. Results: The volume, systolic velocity of blood flow of the external carotid artery, the salivary flow rate, and protein concentration of the parotid gland were significantly more by 11.9, 18, 23, and 8%, respectively, on the dominant side than the nondominant side of mobile phone usage. Conclusion: The study emphasized that prolonged mobile phone usage causes biological changes in parotid gland.

Keywords: Carlson-Crittenden device, mobile phones, modified Schirmer test, parotid gland, saliva, ultrasonography


How to cite this article:
Ranjitha GE, Austin RD, Ramasamy S, Bharathi CS, Angeline D, Sambasivam S. Influence of Handheld Mobiles on Parotid: A Cohort Study. J Indian Acad Oral Med Radiol 2017;29:254-8

How to cite this URL:
Ranjitha GE, Austin RD, Ramasamy S, Bharathi CS, Angeline D, Sambasivam S. Influence of Handheld Mobiles on Parotid: A Cohort Study. J Indian Acad Oral Med Radiol [serial online] 2017 [cited 2018 Dec 12];29:254-8. Available from: http://www.jiaomr.in/text.asp?2017/29/4/254/225567




   Introduction Top


Since the commercial introduction of cell phones, their use has become prolific across the world. Currently, 6 billion people have mobile phones and the initial age of youngest users of the cell phone is estimated as 3 years old. Over time, the number of mobile phone calls per day, the length of each call, and the amount of time people use cell phones have increased drastically.[1] Mobile phones are known to generate heat and emit radiofrequency radiation (RFR), which can be possibly implicated for causing changes in human body. RFR is an important concern of human electromagnetic exposure. This electromagnetic energy penetrates deep into the skin in such a way that the entire body is affected, not just the surface layer; it is the frequency range where the outer membranes of mammalian cells are no longer barriers to electric fields, allowing access of the RFR to subcellular structures.[2]

The parotid gland is one potential target of interest, because hand-held mobile phones (MPH) are typically pressed up against the side of the face in front of the ear where the gland is located and makes it vulnerable to changes, if any, resulting from mobile phone heat and radiation. Parotid glands are the largest salivary glands, situated in front of the ear and behind the ramus of the mandible in proximity to the skin of the face. It secretes serous saliva and is mainly activated after stimulation resulting from smell, taste, and mastication activity. The RFR of the mobile phone can be absorbed in adjacent tissues raising their temperature, modifying cutaneous blood flow, and elevates its perfusion when the device is in close proximity to the skin. Studies have revealed that mobile phone influences the heart rate, showing that sympathetic tone increased and parasympathetic tone decreased during mobile phone use, suggesting that the electromagnetic field generated may affect the autonomic nervous system by modulating the function of the circulatory system.

Previous studies have suggested the possible health effects involved in the use of MPHs, of which several have assessed correlations with parotid gland tumors.[3],[4],[5],[6],[7] Contradicting literature also exists regarding the potential of mobile phone emissions (thermal and radiation effects) to cause notable physiologic, structural, functional, or even carcinogenic changes in the human body.[8] There exist a vague idea on the extent of the harmful effects of mobile radiation on the human body and parotid gland physiologic function in particular.

Hence this study aims to evaluate any possible changes in parotid gland salivary flow rate, volume of the parotid gland, the systolic velocity of the external carotid artery which passes through the parotid gland, and the protein level of saliva secreted by the parotid gland by comparing the dominant and the nondominant side of mobile phone usage of the individuals, thus assessing whether any adverse health effects are associated with the heavy use of mobile phones on parotid glands.


   Materials and Methods Top


A cohort study was planned and conducted during November 2015. This study was to analyze and compare the influence of MPH on parotid gland volume, systolic velocity of external carotid artery, salivary flow rate, and protein concentration in heavy mobile phone users. The study was approved by the Institutional Research Ethics Committee. The individuals for the study were selected among the undergraduate students of a dental college. A total of 50 students were selected for the study. The samples were selected based on the preformed inclusion and exclusion criteria [Table 1]. The individuals selected for the study were explained in detail about the study and the procedure that they were subjected to. A formal informed consent was obtained from all the individuals who participated in the study. The participants filled a preformed questionnaire regarding their mobile phones usage lifestyle and its effects. A detailed intraoral clinical examination was done on each and every individual who participated in the study and the details were recorded in a standard proforma.
Table 1: Inclusion and exclusion criteria for the participants of the study

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Ultrasonography (USG) of the superior lobe of parotid was performed bilaterally in 50 participants. USG was done in Philips USG machine using 4 cm imaging linear probe of 7.5–10 MHz. The systolic velocity of the external carotid artery in parotid gland was also calculated bilaterally using color Doppler imaging of USG. The USG examinations for all the participants were done with the same USG machine by the same radiologist only, and the radiologist was blinded to the side of dominance for MPH usage of the participants in order to avoid observer expectancy bias. The parotid gland volume was measured in ml and the systolic velocity of blood flow in the parotid gland was measured in cm/second.

The saliva secretion rate measurement and saliva sample collection was done between 8 and 12 am. The participants were instructed not to drink, eat, or brush their teeth an hour before the procedure. Subjects were instructed to relax for 5 min before flow rate measurement. Unstimulated parotid saliva flow rate from parotid glands on both sides was measured with the use of a modified Schrimer test strip.[9] The rationale for using unstimulated saliva rather than stimulated saliva was to examine the parotid glands in their resting state (the state in which the gland are for most part of the day, i.e., unstimulated). The modified Schrimer test strip is a 4 cm strip made of filter paper calibrated in 1 mm intervals from 5 to 35 mm along its length (Tear touch – Madhu Instruments Pvt Limited, New Delhi, India) [Figure 1]. The subjects were upright in a dental chair and were asked to swallow once to clear secretions in the mouth. After proper isolation using cotton pellets, the wick end of the Schrimer strips was held at the opening of the Stenson duct for 5 min using cotton pliers and the salivary flow rate was expressed in mm/5 minutes. The side of head frequently preferred for mobile phone use was considered to be the dominant side and the side on which the use was remarkably less was the nondominant side. The dominant side salivary flow rate was compared with the nondominant side of the subjects who participated in the study.
Figure 1: Modified Schrimer strip

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Carlson-Crittenden device was used to collect the saliva sample [Figure 2] from the Stenson's duct of the parotid gland bilaterally.[10] Prior to the placement of the Carlson-Crittenden device, the buccal mucosa was dried with gauze and the Stenson's duct were slightly squeezed to locate the duct orifice. Prior to collection of saliva sample, the salivary flow was stimulated with 2% citric acid, which was applied with a cotton swab on the tongue and the oral part of lower lip for 2 min. 0.5 ml of saliva was then collected from each side of the parotid gland through the Carlson cup in Eppendorf test tubes which was immersed in a 100 ml beaker filled with ice cubes. The collected saliva samples were immediately taken to the lab to determine the protein concentration. The protein concentration was estimated using biuret assay according to which proteins gave an intensive violet blue complex with copper salts in alkaline medium. Iodide was included as an antioxidant. The intensity of the color formed was proportional to the protein concentration in the given sample.[11] A spectrometer or colorimeter measuring at 550 nm was used. The sample and reagents were mixed and incubated for 5 min at 37°C. The net absorbance of the sample, calibration standards, and reference standard at 550 nm in 1 ml cuvettes were read and measured. The color remained stable for 30 min and was compared with the standard. The values of protein concentration were measured in g/dl.
Figure 2: Carlson-Crittenden device

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Mean, median, mode, and standard deviation of the parameters measured were calculated. Pearson correlation test was used to correlate and compare changes in parotid volume, systolic velocity, salivary flow rate, and protein concentration between the dominant and the nondominant side of mobile phone usage. All statistical tests were analyzed to a significant level of 0.05.


   Results Top


In this present study, attempt was made to study the variations in normal physiological functions of parotid gland by comparing the dominant and the nondominant side of mobile phone usage in all the 50 healthy individuals who participated in the study. All the participants of the study were between the ages of 19 and 25 years, with the mean age of 22 years. Out of 50 participants, 20 were males and 30 were females and the ratio of male and female was 2:3. All the 50 participants of the study used only GSM mobile phones. The years of mobile phone usage among the participants were between 2 and 10 years with mean of 5.62 years; 22% of participants used mobile phone for 3 years. The hours of mobile phone usage among the participants were between 2 and 6 h, with the mean of 3.5 h; 66% of the participants used mobile phone for 2 h per day. Out of 50 study participants, 11 (22%) used left as the dominant side for mobile phone usage and 39 (78%) used right as the dominant side for mobile phone usage.

When questioned regarding the ill effects caused due to mobile phone usage, 23 (46%) participants reported heating effect on the ear while using mobile phone on the dominant side of mobile phone usage, 7 (14%) participants reported ear pain and tingling sensation, 1 (2%) participant reported difficulty in hearing, 2 (4%) participants reported disturbances in vision after heavy use of mobile phone, and 17 (34%) participants reported no such ill effects due to heavy mobile phone use.

The parotid gland volume on the dominant side of mobile phone usage was 10.96 ± 3.71 ml and the parotid gland volume on the nondominant side was 9.65 ± 3.01 ml. The parotid gland volume was increased on the dominant side than the nondominant side of the participants by 11.9% with a statistically significant difference (P ≤ 0.00001) [Table 2]. The velocity on the dominant side was 59.748 ± 18.96 cm/s, and on the nondominant side the velocity was 48.98 ± 14.15 cm/s. The systolic velocity of blood flow in the parotid gland was increased in the dominant side than in the nondominant side by 18%, with a statistically significant difference (P = 0.004101) [Table 2]. The salivary flow rate on the dominant side was 6.154 ± 1.29 mm/5 min and the salivary flow rate on the nondominant side was 4.736 ± 1.29 mm/5 min. Thus, the salivary flow rate was increased in the dominant side than the nondominant side of mobile use by 23%, with a statistically significant difference (P = 0.009319) [Table 2]. The protein concentration on the saliva sample collected from the dominant side was 0.987 ± 0.39 g/dl and the protein concentration on the nondominant side was 0.9016 ± 0.44 g/dl. The protein concentration was increased on the dominant side than the nondominant side by 8%, with a statistically significant difference (P = 0.000644) [Table 2]. There was no correlation found in the increase of the parameters on the dominant side with the subsequent increase in the number of years and hours of MPH usage.
Table 2: Parameters measured and compared with dominant and nondominant side of mobile phone users

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   Discussion Top


In this present study, attempt was made to evaluate the variations in normal physiological functions of parotid gland by comparing the dominant and the nondominant side of mobile phone usage in all the 50 healthy individuals who participated. Two emissions from the mobile phones, namely heat generated and RFR, are possibly implicated for causing biological effects in humans. Increase in the parotid gland volume in the dominant side than the nondominant side of mobile phone usage concurred with the findings of earlier studies.[12],[13] The secretory parenchymal tissue expand due to the thermal effect of mobile phones. Such expansion of the rest of the parotid parenchyma could be the reason for increased volume in the side of mobile phone usage. Moreover, previous studies on rats have shown that heat acclimation of rats for up to 28 days changes the ratio of weight to size in the salivary glands, demonstrating that heat can bring structural changes in salivary glands.[14] A unique kind of study investigated the possible thermal effects of microwaves from mobile phones on the facial nerve (FN) and surrounding soft tissue. They concluded that RFRs emitted from a mobile phone can cause temporary FN dysfunction that can be due to temporary temperature increase in the soft tissue around the FN.[15] Thus, it is assumed that thermal effects of mobile phones is the principal factor for causing the ipsilateral volume increase.

Increase in the systolic velocity of the blood flow in external carotid artery on the dominant side of mobile phone use is similar to the findings of a previous study. The study stated that mobile phone influences the heart rate variability parameters in healthy volunteers, showing that sympathetic tone increased and parasympathetic tone decreased during mobile phone use.[13] Additionally, the electromagnetic field generated may affect the autonomic nervous system by modulating the function of the circulatory system.[16] The finding of increased velocity of external carotid blood flow within the parotid gland in the present study can be explained by these two hypotheses.

The salivary flow rate findings of the present study were similar to earlier studies conducted,[12],[13],[17] but contradictory to the findings of one study which stated that the salivary secretion rate was decreased on dominant side of mobile phone usage.[18] The heating of biological tissue is a result of microwave energy absorption by the water content of the tissues. Symptoms reported by many MPH users in previous studies were a feeling of warmth on the ear and behind it and tingling sensation.[19] In the present study also, 46% of the participants have reported a warm sensation on the ear region and 14% have reported a tingling sensation after mobile phone usage. The enriched capillary bed adjacent to the parotid glands may result in an increase of perfusion because of blood vessel propagation over an extensive time of exposure of heat, leading to an increase in the salivary flow rate. Another rationale for increased salivary flow rate from the dominant MPH side is because of thermal effect which may also attribute to secretory parenchymal tissue expansion, which in turn also causes increase in the parotid gland volume on the dominant side of mobile phone use.[12]

The findings of protein concentration are more on the dominant side of mobile phone usage with a significant difference, similar to a study done earlier, which stated that parotid gland salivary concentrations of protein were significantly higher on the right side compared to the left in those that predominantly held mobile phones on the right side.[17] Salivary secretion is regulated by the autonomic parasympathetic and sympathetic nervous system. Hence both are responsible for secretion. The parasympathetic pathway induces more serous saliva and the sympathetic pathway generates the protein secretory component. The effect of mobile phone use is more in sympathetic pathway and less in parasympathetic pathway,[16] hence this might have caused increased protein concentration on the dominant side than the nondominant side of MPH use.

Thus, the study revealed that the MPH influences the parotid gland volume, systolic velocity of blood flow, salivary flow rate, and protein concentration of the parotid gland. The parotid gland volume, systolic velocity of blood flow of the external carotid artery in the parotid gland, the salivary flow rate, and protein concentration of the parotid gland were significantly more by 11.9, 18, 23, and 8% [Table 2] and [Graph 1], respectively, on the dominant side than the nondominant side of mobile phone usage.



The count of increase in all the parameters (parotid gland volume, systolic velocity of blood flow, salivary flow rate, and protein concentration) of the participants were compared with the increase in years and hours of MPH usage, but there was no correlation with the increase in the parameters on dominant side of MPH with the subsequent increase in the number of years and hours of MPH usage. This is similar to the study conducted before.

Head and neck region, especially the parotid gland, is in the closest proximity to the cell phone while in conversation. So the organs and tissues lying in this area are naturally at the greatest risk to any damage the RF waves may incur. Therefore, studies based on the effect of cell phone are needed more. On June 1, 2011, the World Health Organization and the International Association for Research on Cancer declared mobile phones as group 2B agents, possibly carcinogenic to humans. The present study had revealed changes in the parotid gland volume, systolic velocity of blood flow, salivary flow rate, and protein concentration due to MPH use.

More studies should be done in future focusing the effect of MPH use on normal function of the parotid glands on a long-term basis and also should concentrate in assessing other parameters such as free radicals, P53 in saliva of the parotid gland. Thus, further large-scale and long-term follow-up studies are required to validate the findings till date and to lift the shadow of the doubt that still lingers with the use of MPHs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Duan Y, Zhang HZ, Bu RF. Correlation between cellular phone use and epithelial parotid gland malignancies. Int J Oral Maxillofac Surg 2011;40:966-72.  Back to cited text no. 4
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Acar GO, Yener HM, Savrun FK, Kalkan T, Bayrak I, Enver O. Thermal effects of mobile phones on facial nerves and surrounding soft tissue. Laryngoscope 2009;119:559-62.  Back to cited text no. 15
    
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Kodavanji B, Mantur VS, Kumar NA, Pai SR. A pilot study on long term effects of mobile phone usage on heart rate variability in healthy young adult males. J Clin Diagn Res 2012;6:346-9.  Back to cited text no. 16
    
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    Figures

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    Tables

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