|Year : 2013 | Volume
| Issue : 3 | Page : 122-126
Mobile phones: Its effect on hearing
Mahesh Chandra Hegde, Vijendra S Shenoy, Panduranga M Kamath, Raghavendra A Rao, Vishnu Prasad, Bindu Sara Varghese
Department of Ear, Nose and Throat and Head and Neck Surgery, Kasturba Medical College, Mangalore, Manipal University, Manipal, Karnataka, India
|Date of Web Publication||2-Sep-2013|
Vijendra S Shenoy
Department of Otolaryngology, Kasturba Medical College Hospital, Attavar, Mangalore - 575 001, Manipal University, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Widespread concerns have been raised about the possibility that exposure to the radio frequency fields from mobile telephones or their base stations could affect people's health. Materials and Methods: Effect on hearing in 120 mobile phone users and nonusers between age group of 18-30 years were studied over 3 years. Group 1 using mobile phone more than 1 hour per day for more than a year and group 2 no usage or less than 1 hour per day for less than a year. Results: Those using phones for 2-3 hours daily, loss of 5 dB in 10%, 10 dB in 3.3%, and 15 dB in 1.6% were noted. Also loss of 5 dB in 6.6% and 10 dB in 3.3% were noted in those using 3-4 hours daily. Sensorinueral hearing loss was seen in 26.6% of the subjects in study group and 3.3% in control group. Conclusion: Our study did not show any significant hearing loss in mobile phone users.
Keywords: Hours of exposure, Mobile phone, Sensorineural hearing loss, Years of exposure
|How to cite this article:|
Hegde MC, Shenoy VS, Kamath PM, Rao RA, Prasad V, Varghese BS. Mobile phones: Its effect on hearing. Indian J Otol 2013;19:122-6
| Introduction|| |
The mobile phone is a ubiquitous piece in this modern world. An estimated 85% of Americans, 60% of the British, and perhaps 45% of Indians use it, as of today. Of particular concern to the World Health Organization (WHO) is the fact that, if any adverse health effect is established from mobile phone use, it will be a global concern because developing countries are establishing this technology in preference to more expensive fixed line systems. The concern relate to the emission of radio frequency (RF) radiation from mobile phones and the base stations that receive and transmit signals. This study was planned to study the impact of mobile phone usage on hearing.
| Materials and Methods|| |
The study was conducted in department of otolaryngology, head and neck surgery and department of audiology, speech and language pathology, Kasturba Medical College Hospital and government Wenlock Hospital, Mangalore over a period of 3 years from 2009 to 2012. The study included mobile phone users and non-users between the age group of 18 and 30 years. Mobile phone users for more than 1 year with minimum usage of more than 1 hour per day were included in the study. Those using hearing aids, with history of chronic suppurative otitis media, history of head trauma or head fracture, family history of hearing defects, and people exposed to constant noise pollution or working noisy environment were excluded from the study.
All the candidates were subjected to a detailed history taking with special emphasis on duration, pattern, usage, and type of mobile and hearing loss. Detailed enquiry was made about onset and progression of hearing loss if any. An enquiry was made in to any associated illness like diabetes mellitus and systemic hypertension. Any history of childhood ear discharge was asked for. The occupational exposure to loud noise and personal habits like smoking and alcohol were asked for and recorded. Detailed clinical examination was performed including a general systemic examination and thorough examination of the ear using otoscope. The character of the tympanic membrane was observed in detail. The three standard tuning fork tests (Weber's, Rinne's, and absolute bone conduction tests) were done. All the candidates underwent a pure tone audiometry (PTA) and immitance studies and graphs were plotted. Pure tone audiograms were assessed for type and percentage of hearing loss.
| Results|| |
The study was divided in to two groups: group 1, those using mobile phones more than 1 hour per day for more than 1 year and group 2, no usage or using for less than 1 hour for less than a year. Statistical analysis was done using Chi-square and Student's t-tests and P-value of < 0.05 was considered as significant. The two groups were found to be comparable with respect to sex and age distribution (P > 0.05, which was statistically insignificant).
Symptoms on presentation
Blocked sensation (15%) followed by tinnitus (10%) and difficulty in hearing (3.3%) were the main symptoms in the study group at the time of presentation [Table 1]. None of the subjects in control group had any symptoms at the time of presentation. Statistically, blocked sensation and tinnitus were significant with P value < 0.05, whereas difficulty in hearing, difficulty in speech discrimination, and loudness intolerance were statistically insignificant (P value > 0.05) [Table 1].
Hours of exposure
In our study group 21 (35%) subjects had 1-2 hours of exposure, 25 (41.7%) had 2-3 hours, and 14 (23.3%) had 3-4 hours exposure to mobile phones per day. The Chi-square value was found to be 120 and P value being 0.000, which was statistically significant [Table 2].
Hours of exposure vs hearing loss (dB)
In our study group, those of the subjects using mobile phones for 2-3 hours daily, 5 dB loss was noted in 10%, 10 dB loss in 3.3%, and 15 dB loss in 1.6%. Also 5 dB loss in 6.6% and 10 dB in 3.3% was noted in those using mobile phones for 3-4 hours daily [Table 3].
Years of exposure
Mean years of exposure in group 1 was 2.47 years, while that of group 2 was 0.12 years with a P value < 0.05, which was statistically significant [Table 4].
In our study group, 32% of those who have been using mobile phone since 2 years had sensorineural hearing loss and 22% of those who have been using it since 3 years had sensorineural hearing loss [Table 5].
Type of exposure
Types of exposure noted in the study group were either intermittent or continuous, where continuous exposure was seen to be associated more with minimal sensorineural hearing loss noted in the study group, the association of which was compounded by the increasing hours and years of exposure. Exposure was of intermittent type in the control group.
Type of deafness
Sensorineural hearing loss was seen in 26.6% of the subjects in the study group and 3.3% in the control group [Table 6] and [Table 7].
In the group 1, 10% and 16.6% of cases had minimal sensorineural hearing loss in the right and left ear, respectively, while in group 2, 3.3% had sensorineural loss in right ear only.
| Discussion|| |
The widespread use of mobile phones has been going sky-high over the past decade and now its use is an essential part of business, commerce, and society. The fact that so many people own mobile phones attests to their perceived importance to the general public. Widespread concerns have been raised about the possibility that exposure to the RF fields from mobile phones or their base stations could affect people's health. Such has been the rapid growth of the mobile telecommunications. There are two direct ways by which health could be affected as result of exposure to RF radiation.  These are thermal (heating) effects caused mainly by holding mobile phones close to the body and also as a result of possible non-thermal effects. The well-liked belief is that adverse health effects can be induced mostly by the heating effect of global system for mobile communication (GSM) radiation. The reported adverse health effects and extensive portfolio of non-thermal effects that have been published in the scientific literature during the past few years, which indicates that the kind of radiation now used in GSM phone can and does affect living organisms in various non-thermal ways. Phones emit a pulsed high frequency electromagnetic field,  which may penetrate the scalp and the skull. These electromagnetic fields are known to alter distinct aspects of the brains electrical response to acoustic stimuli. The extensive exposure to microwave radiation has been found to affect a wide variety of brain functions  such as electrical activity, electrochemistry, , permeability of the blood-brain barrier,  and immune systems.  Microwaves are known to non-thermally affect the dopamine-opiate system , of the brain and to increase the permeability of the blood-brain barrier.  Exposure to high density microwaves can cause detrimental effects on the eyes, testis, and other tissues and induce significant biological changes through thermal actions.  The temporal region near the phone antenna appeared to be under the most intensive heating. Ultrahigh frequency radiation  induces significant changes in local temperature and in physiologic parameters of central nervous and cardiovascular systems. Besides a hypotonic effect  with shortening of sleep onset latency, a rapid eye movement (REM) suppressive effect with reduction of duration and percentage of REM sleep was also found. The number of complaints was higher for people using the digital (GSM) systems with pulse modulated fields, than for the using the analogue nordisk mobile telecommunication  (NMT) system. RF exposure from mobile phones is concentrated to the tissue closest to the handset, which includes auditory nerve.  The effects on neuronal electrical activity, energy metabolism, genomic responses, neurotransmitter balance, blood-brain barrier permeability, cognitive function, auditory function, sleep, and various brain diseases including brain tumors are of concern. Most of the reported effects are small as long as the radiation intensity remains in the non-thermal range, and none of the research reviewed gives an indication of the mechanisms involved at this range.
Of particular concern to the WHO is the fact that, if any adverse health effect is established from mobile phone use, it will be global concern because developing countries are establishing this technology in preference to the more expensive fixed line systems. Keeping in view the hazards of the mobile phones, the present study was designed to investigate the association of use of mobile phones and hearing loss.
Age and sex
The study and control groups were found to be comparable with respect to the sex distribution.
In our study, blocked sensation (15%) followed by tinnitus (10%) and difficulty in hearing (3.3%) were the main symptoms at the time of presentation. None of the subjects in the control group had any symptoms at the time of presentation. In contrast, in a study conducted by l-Khlaiwi et al.,  the overall mean percentage for presenting complaints in all group were headache (21.6%), sleep disturbance (4%), tension (3.9%), fatigue (3%), and dizziness (2.4%). Meo and Drees  in a study showed about 34.59% of problems were related with impaired hearing, earache and/or warmth on the ear, and 5.04% of complaints with decreased and/or blurred vision.
Years of exposure
In our study, 32% of those who have been using mobile phone since 2 years had sensorineural hearing loss and 22% those who have been using it since 3 years had sensorineural hearing loss. This indicates that the minimal hearing loss (5-15 dB) noted in the study group depended not only on years of exposure, but also on hours of exposure per day and type of exposure. Panda et al.,  in their study assessed the effects of chronic exposure to electromagnetic waves emitted from the GSM mobile phones on the auditory function in users. No significant differences were found for high frequency hearing loss, distortion product oto-acoustic emissions (DPOAE), auditory brain stem response (ABR), and middle-latency responses (MLR) in the users. High frequency hearing loss was seen in subjects using the phone for more than 4 years (P = 0.04).
In our study, we also observed that none of the subjects in the study group suffered from significant hearing loss (>25 dB). This correlates with the findings of Davidson and Lutman  in his "survey of mobile phone use and their chronic effects on the hearing of a student population." High or long-term users reported no worse hearing, tinnitus, or loss of balance than low or short-term users. However, there appear to be no harmful effects of mobile phone usage on their audiovestibular systems within the range exposure of the study, in so far as can be detected by the self-report method employed. Similarly, in a study by Sievert et al.,  to investigate the biological effect of the high frequency radiation produced by the GSM mobile phone on the inner ear with its sensors of the vestibular and auditory systems showed that the electromagnetic fields generated in using the mobile phone do not have an effect on the inner ear and auditory system to the colliculus inferior in the brain stem and on the vestibular receptors in the inner ear and vestibular system.
Hours of exposure
Although none in our study group had significant hearing loss, we observed an increase in hearing threshold between 5 and 15 dB in the study group (26.6% of the subjects in the study group and 3.3% in control group had hearing loss of 5 dB. Nearly 10 dB hearing loss was noted in the study group in 6.6% and 15 dB in 1.6%, especially in those exposed to mobile phone usage for more than 2 hours per day, more so if the pattern of usage is continuous. This relates to the study by Callejo and Santamaria  in a group of 323 healthy and normoacoustic volunteers who were usual customers of mobile phone for whom an audiometric evaluation was made at the beginning of its use and 3 years later, inquiring about the periods of time per day and ear employed on direct contact contacts with the phone. A healthy and normoacoustic control group of non-users was studied too. Audiometric curve was similar in cases and controls at beginning of the study. After this follow-up, cases showed an increase in hearing threshold between 1 and 5 dB more than controls in speech tones (P < 0.001).
Our findings were also in agreement with the study by Oktay and Dasdag  of department of otolaryngology, medical school of Diyarbakir, Turkey, who conducted a study to investigate the effects of radiation emitted by mobile phones on the hearing of users. The study was carried out on three groups: (1) 20 men who have used cellular phone frequently and spoken approximately 2 hours per day for 4 years; (2) 20 men who have used a cellular phone for 10-20 minutes per day for 4 years; and (3) 20 healthy men who have never used a cellular phone (control group). Brainstem-evoked response audiometric (BERA) and PTA methods were used to measure the effects of exposure on hearing function of the subjects. The BERA results showed no differences among the groups
(P > 0.05), in PTA measurements, no differences were observed between moderate mobile phone users (10-20 minutes per day) and the control subjects. However, detection thresholds in those who talked approximately 2 hours per day were found to be higher than those in either moderate users or control subjects. Differences at 4000 Hz for both bone conduction and air conduction for right ears, and 500 and 4000 Hz bone and air conduction for left ears were significant for mean hearing threshold. This study shows that a higher degree of hearing loss is associated with long-term exposure to electromagnetic field generated by cellular phones.
A case of sensorineural hearing loss due to GSM mobile was reported in Saudi Medical journal in 2007.  While, those in our study with mobile phone usage of less than 2 hours per day showed normal audiometric curves, which can be related to study by Sievert et al.,  in 12 healthy test persons, with normal hearing. Auditory brain stem reflexes recordings were performed before, during, and after exposure to electromagnetic emissions by standardized mobile phone devices. Two modes of electromagnetic emissions fields were administered: pulse and continuous. For acoustic stimulation, simultaneous to field exposure, special "pug-in" earphones had to be used. There are no adverse effects of mobile phone emissions on the ear function, at least on a short-term range.
A WHO fact sheet updating conclusions and recommendations regarding health effects from mobile phone use and exposure to base stations was published in June 2000 (WHO 2000).  It states that none of the recent reviews have concluded that exposure to the RF fields from mobile phones or their base stations cause any adverse health consequence. However, there are gaps in knowledge that have been identified for further research to better assess health risks.
In the mean time, WHO recommend the following:
It is advisable therefore that the use of mobile phones is a risk factor for health hazards and suggest that excessive use of mobile phones should be avoided by health promotion activities, such as group discussions, public presentations, and through electronic and print media sources. In addition, we also suggest that more research is required to observe the effects of mobile phones with different systems of the human body along with clinical examination.
- Strict adherence to health-based guidelines. International guidelines have been developed to protect everyone in the population: mobile phone users, those who work near or live around base stations, as well as people who do not use mobile phones.
- Precautionary measures: Present scientific information does not indicate the need for any special precautions for use of mobile phones. If individuals are concerned, they might choose to limit their own or their children's RF exposure by limiting the length of calls, or using "hands free" devices to keep mobile phone away from the head and body.
| Conclusion|| |
Our study did not show any significant hearing loss in mobile phone users since 0-25 dB hearing loss is taken for all practical purpose as normal. But still we observed a minimal hearing loss of 5-15 dB in those exposed to mobile phone usage of more than 2 hours per day, the pattern of use being continuous. Hence we recommend a long-term follow up study in long-term mobile users before we can come to a definitive conclusion.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]