|Year : 2011 | Volume
| Issue : 3 | Page : 97-100
Prevalence of sensorineural deafness in habitual mobile phone users
GC Sahoo1, Honeymol Sebastian2
1 Department of ENT, Rajah Muthiah Medical College, Annamalainagar, Chidambaram, Tamil Nadu, India
2 Department of PG Trainee in ENT, Rajah Muthiah Medical College, Annamalainagar, Chidambaram, Tamil Nadu, India
|Date of Web Publication||26-Dec-2011|
G C Sahoo
Department of ENT, Rajah Muthiah Medical College, Annamalainagar, Chidambaram, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Introduction : Mobile phone usage is widespread and concerns have been raised on the safety of its long-term usage. The electromagnetic fields emitted from mobile can penetrate skull and deposit energy 4-6 cm into the brain resulting in heating of the tissue. In this study, we explore a possible relationship between prolonged mobile phone usage and sensorineural deafness. Materials and Methods: The study was conducted in a medical college situated in rural India. A total of 100 persons between the age group of 20-45years using mobile phone for at least 5 years are selected and screened for sensorineural deafness. Use of cellular phones was assessed by a questionnaire. Mean number of daily calls and minutes were asked for to calculate the cumulative use in hours for all years. The most frequently used ear during cellular phone calls was noted, or whether both ears were used equally. Otoscopic examinations were performed by an otolaryngologist before testing in order to rule out any external or middle ear pathology that could affect audiometric measurements. The hearing levels of subjects were tested using pure tone audiometry. Results : One hundred subjects who are habitual mobile phone users were screened by pure tone audiometry. It is found that the prevalence of sensorineural deafness was 3% and there is a linear relationship between the duration of mobile phone use and the degree of the severity of deafness. Conclusion : The prevalence of sensorineural deafness in our study in habitual mobile users is 3%. It is not clearly known whether mobile phone use is the direct cause of deafness in these subjects but the absence of other causes might point towards its etiological role.
Keywords: Audiometry, Mobile phone, Radiofrequency energy, Sensorineural hearing loss
|How to cite this article:|
Sahoo G C, Sebastian H. Prevalence of sensorineural deafness in habitual mobile phone users. Indian J Otol 2011;17:97-100
| Introduction|| |
India is the world's fastest growing wireless market, with 752 million mobile phone subscribers as of February 2011. It is also the second largest telecommunication network in the world after China in terms of number of wireless connections. The Indian mobile subscriber base has increased in size by a factor of more than 100, since 2001 when the number of subscribers in the country was approximately 5 million.
Mobile phones are two way radios that transmit and receive information via radio waves also known as radiofrequency (RF) energy global system for mobile (GSM) communications is the world's most popular standard for mobile telephony systems. GSM networks operate in a number of different carrier frequency, with most 2G GSM networks operating in the 900 MHz or 1800 MHz bands and most 3G networks operate in 2100 MHz. CDMA 2000 (code division multiple access) is the other popular technology standard which uses CDMA channel access, CDMA uses frequencies from 824 MHz to 894 MHz in India.
These frequencies fall in the microwave range of the electromagnetic spectrum. In contrast to ionizing radiation, electromagnetic fields emitted from cellular telephones do not have enough energy to break chemical bonds or damage DNA. Electromagnetic radiation from a cell phone can penetrate the skull and deposit energy 4-6 cm into the brain. This can potentially result in a heating of the tissue of up to 0.1°C. , Therefore, it has been debated whether these fields could damage the tissue or not. The radio waves emitted by a GSM handset can have a peak power of 2 W, and a US analogue phone had a maximum transmit power of 3.6 W. Other digital mobile technologies, such as CDMA2000 use lower output power, typically below 1 W. The maximum power output from a mobile phone is regulated by the mobile phone standard and by the regulatory agencies in each country. Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the body when exposed to a radio frequency (RF) electromagnetic field. It is defined as the power absorbed per mass of tissue and has units of watts per kilogram (W/kg). SAR is usually averaged either over the whole body, or over a small sample volume (typically 1 g or 10 g of tissue). The value cited is then the maximum level measured in the body part studied over the stated volume or mass.
International Commission on Non-Ionising Radiation Protection (ICNIRP) is a body of independent scientific experts established with an aim to provide information and insight into the potential health hazards of exposure to non-ionising radiation. According to ICNIRP guidelines for limiting exposure to time varying electric, magnetic and electromagnetic fields, the maximum SAR value for mobile phones has been set at 2 W/kg localized for the head and the trunk (of a human) in the frequency range of 10 MHz to 10 GHz. It means in countries such as India where these guidelines are adopted, the specific absorption rate (SAR) of every mobile phone sold in the country should be less than 2 W/kg.
Many scientific studies have investigated possible health effects of mobile phone radiations. Exposure to electromagnetic fields has been linked to different forms of cancer ,,,, (e.g., lymphoma, brain tumors, leukemia), various neurological disease (Alzheimer's disease), sleep disturbances, , and genotoxic effects.  Since ear is the closest organ to mobile phones receiving higher energy deposition than other organs, the effects of mobile phone radiation on hearing has been debated. , Here we aim to determine the prevalence of sensorineural deafness in habitual mobile phone users.
| Materials and Methods|| |
The study was conducted in a medical college situated in rural India. A total of 100 persons between the age group of 20-45 years using mobile phone for at least 5 years are selected and screened for sensorineural deafness. Subjects with, middle ear pathology or a history of noise exposure were not enrolled in this study. Also people with history of diseases known to affect hearing (meningoencephalitis, cranioencephalic trauma) were excluded. Use of cellular phones was assessed by a questionnaire. Mean number of daily calls and minutes were asked for to calculate the cumulative use in hours for all years. The most frequently used ear during cellular phone calls was noted, or whether both ears were used equally. Otoscopic examinations were performed by an otolaryngolgist before testing in order to rule out any external or middle ear pathology that could affect audiometric measurements. The hearing levels of subjects were tested using pure tone audiometry. All tests were performed in a sound-treated room.
Review of literature
A review of literature failed to prove conclusively that prolonged mobile phone use affects hearing. The European project EMFnEAR was undertaken to assess potential changes in human auditory function after a short-term exposure to radiofrequency (RF) radiation produced by Universal Mobile Telecommunication System (UMTS) mobile phones. It is concluded that UMTS short-term exposure at the maximum output of consumer mobile phones does not cause measurable immediate effects on the human auditory system. Ozturan et al concluded that a 10-min exposure to the EMF emitted from a mobile telephone had no effect on hearing, at outer ear, middle ear, and cochlear levels. Panda et al suggested long-term and intensive mobile phone use may cause inner ear damage. Studies demonstrated increase in pure tone threshold in subjects exposed to mobile phone radiations. , However Stefanics et al and Mora et al found that a single exposure of 900 MHz EMF emitted by a commercial mobile phone does not produce measurable immediate effects in the latency of auditory brainstem waves. Kwon et al investigated the possible effects of the electromagnetic field emitted by an ordinary GSM mobile phone on brainstem auditory processing. However it did not find any evidence that short-term exposure to mobile phone electromagnetic field affect the transmission of sensory stimuli from the cochlea up to the midbrain along the auditory nerve and brainstem auditory pathways. However, no safe conclusions can be drawn regarding the potential harmful effects of mobile phone use. Studies are underway to investigate possible effects of mobile phone use on the auditory system and the CNS. These along with other studies are expected to further clarify whether mobile phone use truly presents a health hazard.
| Observations and Discussion|| |
Our study consisted of 62 male participants and 38 female participants. A questionnaire was filled for each participant noting down the age, duration of mobile phone use and the brand of mobile being used. Subjects were asked for symptoms of tinnitus, vertigo headache, ear discomfort or fullness of ear, exposure to loud noise, and previous history of ear discharge and hearing loss. A thorough ENT examination was carried out and pure tone audiogram was performed. The average age of the participants was 32 years. Duration of mobile phone use ranged from 5 min to 120 min per day. Five patients (5%) complained of tinnitus and 4 patients (4%) had vertigo. Ear discomfort was reported by 10 patients (10%) and fullness in ear was reported by 8 patients (8%). Subjects with previous hearing loss or ear discharge were excluded from the study [Figure 1].
Sensorineural deafness in the audiogram is suggested by hearing loss at higher frequencies and no gap between air and bone conduction curve in audiometry. WHO recommended the following classification on the basis of pure tone audiogram taking the average of thresholds of hearing for frequencies of 500, 1000, and 2000 Hz with reference to ISO: R. 389-1970 (international calibration of audiometers)
- Mild 26-40 dB
- Moderate 41-55 dB
- Moderately severe 56-70 dB
- Severe 71-91 dB
- Profound >91 dB
In our study three subjects (3%) were found to have sensorineural deafness. Tuning fork test carried out in these subjects revealed positive Rinne's test in the affected ear and lateralisation to the unaffected ear in Weber's test. First subject had 45 dB hearing loss at 2000 Hz. The duration of mobile phone use was 7 years with an average daily use of 45 min per day. Second subject had hearing loss of 50 dB at 2000 Hz with duration of use of 1 h per day for the last 5.5 years. Third person complained of tinnitus and had 60 dB hearing loss at 4000 Hz. The mobile phone use was 2 h per day for 7 years.
The corrected average daily use for 5 years has been calculated using the formula.
The corrected average daily use and hearing loss are tabulated in [Table 1]. It has been found that a more or less linear relationship exist between the average daily use and severity of deafness. This has been depicted in [Figure 2].
|Figure 2: Relationship between average daily use and severity of deafness|
Click here to view
| Conclusions|| |
The prevalence of sensorineural deafness in our study population is found to be 3%. The patients were not aware of deafness though deafness is established with the audiometry. The severity of the deafness seems directly correlated with duration of the mobile phone use. It is not clearly known whether mobile phone use is the direct cause of deafness in these subjects but the absence of other causes might point towards its etiological role. Further case control or cohort studies are required in order to establish a definite causal relationship between mobile phone use and sensorineural deafness.
Limitations of the study
- Small sample size
- Different brands of mobile phones differ in their SAR value which is not taken into account in this study
- Lack of control population may not definitely establish a causal relationship
| Acknowledgments|| |
The authors thank Dr. Mohan Jose for skilful computer assistance and assistance with preparation of tables.
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[Figure 1], [Figure 2]