Hearing Loss From Mobile Phone Use Essay

Mobile phones have become a part of modern life style. There has been rapid boom in the number of mobile phones in the recent decade. This rapid worldwide expansion of mobile telephones raises questions regarding possible effects of the emitted radiofrequencies on the health of the consumers. The electromagnetic waves can affect the human health ranging from increase the blood pressure, cause memory loss and induce migraines, hearing impairment to even cancer can also occur. Of all the anatomical structures, the ear is in the closest proximity to the mobile phones, hence most potential organ system to be damaged by the electromagnetic waves emitted from the mobile phones.

Pure tone audiometry is a key hearing test for assessment of hearing threshold of the individual. It determines the degree of hearing loss and also type and configuration of hearing loss. Pure tone audiometry uses both air and bone conduction audiometry, the type of loss can be identified by the air-bone gap.

In our study, while comparing the results of pure tone audiometry in controls (n=60) and total cases (n=60), it was found that in control group 51 individuals had normal hearing threshold, 08 had mild hearing loss and 01 had moderate hearing loss. Of the total cases, 39 had normal hearing threshold, 19 had mild hearing loss and 2 had moderate hearing loss. No individual in the cases or control group had severe or profound hearing loss. Chi square test with yates correction was applied for statistical analysis of the data, and difference was found to be significant (p value<0.05). Hearing Loss From Mobile Phone Use Essay

While comparing, sub groups of cases (group A, Group B) to controls for pure tone audiometry, it was found that in group A (n=30) 20 individuals had normal hearing threshold, 09 had mild hearing loss and 01 had moderate hearing loss. While in group B, 19 had normal hearing threshold, 10 had mild hearing loss and 01 had moderate hearing loss. Chi square test with yates correction was applied for statistical analysis of the data, and difference was significant (p value<0.05) for group B, but was insignificant (p value>0.05) for group A.

Hegde MC et al (2013) reported that there is no significant hearing loss in mobile phones users as compared to non- users when assessed by pure tone audiometry.

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Kerekhanjanarong V et al (2005) subjected 98 mobile phone users to audiometry, tympanometry, otoacoustic emission (OAE) and auditory brain stem evoked response (ABR). When they compared the audiogram, both pure tone and speech audiometry, between the dominant and non-dominant side, it indicated that there is no significant difference. When they focused on the eight subjects that used the mobile phone for more than 60 minutes per day, they found that the hearing threshold of the dominant ears was worse than the non-dominant ear.

Oktay MF et al (2006) studied the effects of mobile phones on hearing by pure tone audiometry and brainstem evoked audiometry response. They reported a high frequency hearing loss in subjects exposed to electromagnetic frequencies of mobile phones when assessed by pure tone audiometry.

Panda NK et al (2010), reported high frequency hearing loss in long term mobile phone users as compared to non-users.

Godson R. E. E. Ana et al (2012) by their study gave the results that hearing impairment was higher in those reporting longer duration of mobile phone use.

Hitesh patel et al (2013) by pure tone audiometry, found that there is increased degree of hearing loss in long term mobile phone users than control subjects with mean hearing loss was more in dominant ear compared to non-dominant ear.

Results of pure tone audiometry, in presnt study show that use of mobile phones has detrimental effect on hearing threshold. Results also show that longer the duration of mobile phone usage, more is the damage to the ear. The results are in concurrence with the other similar studies done in our country and abroad (Kerekhanjanarong V et al 2005), (Oktay MF et al, 2006), (shayani nasab M eta al, 2006), (shayani nasab M eta al, 2006), (Panda NK et al, 2010), (Godson R. E. E. Ana et al, 2012), (Hitesh Patel et al, 2013). Hearing Loss From Mobile Phone Use Essay

Brain stem evoked response audiometry or BERA is an important non-invasive device of knowing dysfunction of brainstem which is cumbersome and time consuming by conventional examinations. It encompasses diagnosis of lesion ranging from 8″ nerve to the auditory cortex and it is based upon the study of electrical potentials generated by the auditory pathway in response to external stimuli by means of surface electrodes over scalp and it consists of 7 waves. (Cochlear nerves – waves I and II, Cochlear nucleus – wave III, Superior olivary complex – wave IV, Nuclei of lateral lemniscus – wave V, Inferior colliculus – waves VI and VII)

In the present study, comparing the latencies of the controls (n=60) and total cases (n=60), latencies of wave I, III, V and interpeak latency of I-V of controls 1.521+ 0.185, 3.745+0.216, 5.623+0.218 and 4.102+0.310 to that of total cases 1.602+0.226, 3.842+0.264, 5.681+0.291, 4.079+0.287 it was seen that latencies of wave I and wave III were significantly increased in cases.

While comparing the latencies of the controls (n=60) and cases group A (n=30), latencies of wave I, III, V and interpeak latency of I-V of controls 1.521+0.185, 3.745+0.216, 5.623+0.218 and 4.102+0.310 to that of cases group A 1.594+0.235, 3.836+0.297, 5.666+0.284, 4.072+0.276 it was seen that latencies of wave I, III, V and interpeak latency I-V were not significantly increased in cases.

While comparing the latencies of the controls (n=60) and cases group B (n=30), latencies of wave I, III, V and interpeak latency of I-V of controls 1.521+0.185, 3.745+0.216, 5.623+0.218 and 4.102+0.310 to that of cases group B 1.610+0.219, 3.849+0.233, 5.697+0.301, 4.086+0.302 it was seen that latencies of wave I and wave III were significantly increased in cases.

Oktay MF et al (2006) studied the effects of mobile phones on hearing by pure tone audiometry and brainstem evoked audiometry response. Interpeak latencies of I-V, I-III, III-V were studied. No significant difference was reported in the interpeak latencies in users and non-users.

Davidson HC et al (2007) studied the effects of chronic mobile phone usage on hearing, and reported that there is no harmful effects of mobile phone usage on their audiovestibular systems within the range of exposure of the study.

Counter et al. (1993) investigated the effect of long-term transcranial electromagnetic stimulation on the auditory brainstem and cortical evoked responses over a period of 12 months in rabbits. Rabbits were exposed to Electromagnetic frequency with 0.2 Tesla power, by using a magnetic coil placed on the right ear of the animals, while the left ear was protected. Differences after exposure were recorded with the use of ABR. The difference in the amplitude and the latency of wave III was observed. The amplitude and latency of the other waves showed no significant changes before and after exposure. Subsequent histological examination of the cochlear nucleus and inferior bigeminal bodies revealed no structural and morphological changes. Hearing Loss From Mobile Phone Use Essay

Kellenyi et al. (2005) reported that pulsed EMF emitted by a cellular phone for 15 min caused a 0.2 ms delay in the wave V of ABR.

Kaprana AE et al (2011) studied the time related changes in auditory pathway during mobile phone electromagnetic exposure in rabbits. In their study they reported that absolute latency of wave III, and interpeak latencies of I-V, and III-V were significantly prolonged after exposure to electromagnetic frequencies in a time dependent manner.

P Karthikeyan et al (2014) did a study named “Hearing evaluation in mobile phone users at tertiary care hospital”. They took hundred subjects and categorized them into two cases groups, Group 1 (<2h/day) and Group 2 (>2h/day). Non invasive procedures were done to assess the hearing status: Pure tone audiometry, distortion product otoacoustic emissions (DPOAE) and brainstem evoked response audiometry (BERA). The study resulted that variable degree of hearing loss was found on DPOAE and BERA in mobile phone users. They also found that hearing loss was higher in group 2, and hence reported that “intensity of hearing loss is found to be directly proportional to the duration of mobile phone usage”

Shilpa khullar et al (2013) studied the effects of electromagnetic frequencies generated by mobile phones (GSM) on auditory brainstem response. They reported that latencies of wave I to V as well as interpeak latency of wave I-V, I-III and III-V were significantly increased in individuals using mobile phones for 30 min/day for 10 years.

In many studies it has been shown that short term exposure to electromagnetic frequencies (few minutes) done not prolong the latencies of waves of ABR.

In our study, we found significantly increased latencies of wave I and III in total cases and in Group B. Different waves of BERA correspond to different parts of auditory pathway. These peaks are considered to originate from the following anatomical sites: Cochlear nerves – waves I and II, Cochlear nucleus – wave III, Superior olivary complex – wave IV, Nuclei of lateral lemniscus – wave V, Inferior colliculus – waves VI and VII. Latency of Wave I is increased when there is some cause of hearing loss in peripheral hearing or cochlear pathology or disease of auditory nerve. Electromagnetic frequencies of mobile phones causes damage to nerve as well (Salford LG et al, 2003). Since, auditory nerve is closest to electromagnetic field of mobile phone, it is most likely nerve to be damaged. Therefore, damage to auditory nerve due to EMF can be the cause of increased latency of wave I. Hearing Loss From Mobile Phone Use Essay

Electromagnetic frequencies emitted from mobile phones causes increased incidence of brain tumour and acoustic neuroma (INTERPHONE study, Sweden, 2004). There is significant increase in occurrence of acoustic neuroma in persons using mobile phones for more than 10 years (Hardell L, 2007). Acoustic neuroma is a benign tumour on the auditory nerve that usually grows slowly over a period of years before it is diagnosed. BERA gives good diagnostic support in the intrinsic brainstem lesions by suggesting changes in the generator sites of the component waves, and waves are characteristically prolonged in acoustic neuroma, and help in early suspicion and detection of the tumour (Antonelli AR, 1987). Cerebellopontine angle is the most common site for acoustic neuroma. Wave III originates from cochlear nucleus, and anatomical location of cochlear nucleus is at cerebellopontine angle (Klose AK et al).

In our study, there is increased latency of Wave III in total cases and in Group B. Wave III originates from cochlear nucleus, which is present at cerebellopontine angle. EMF are also known to cause acoustic tumour in persons using cell phones for more than 10 years, and most common site for acoustic neuroma is cerebellopontine angle. It may be the reason that neuron tissue damage that occurs in due to exposure to electromagnetic frequency of mobile phones, may be the reason for increased latency of wave III, much before the damage is enough to cause the tumour.

An otoacoustic emission (OAE) is a sound which is generated from the inner ear. When sound stimulates the cochlea, the outer hair cells vibrate. These vibrations produce a nearly inaudible sound that echoes into the middle ear. This sound can be measured with a small probe inserted into the external ear canal. Distortion product otoacoustic emissions (DPOAE) are responses generated when the cochlea is stimulated simultaneously by two pure tone frequencies whose ratio is between 1.1 to 1.3. DPOAEs produced are largest at this separation of the two primary tones. In our study, sounds at 65dB and 55 dB were used to evoke otoacoustic emissions. Combinations of the primary tones result in DPOAEs, the largest and most commonly studied one is the 2f1-f2 frequency, was measured.

In our study, while comparing the results of distorted product otoacoustic emission (DPOAE) in controls (n=60) and total cases (n=60), it was found that in control group 41individuals passed the test and 19 individuals failed the test, while in cases, 34 individuals passed the test and 26 individuals failed the DPOAE test. Chi square test was applied for statistical analysis of the data, and results were not found to be significant (p value>0.05). Hearing Loss From Mobile Phone Use Essay

While comparing the results of distorted product otoacoustic emission (DPOAE) in controls (n=60) and cases Group A (n=30), it was found that in cases group A, 19 individuals passed the test and 11 individuals failed the DPOAE test. Chi square test was applied for statistical analysis of the data, and results were not found to be significant (p value>0.05).

On comparing the results of distorted product otoacoustic emission (DPOAE) in controls (n=60) and cases Group B (n=30), it was found that in cases group B, 15 individuals passed the test and 15 individuals failed the DPOAE test. Chi square test was applied for statistical analysis of the data, and results were not found to be significant (p value>0.05).

The European project EMFnEAR, was done to assess the harmful effects of short term electromagnetic waves emitted from UTMS mobile device over the outer hair cells. Functioning of outer hair cells was assessed by DPOAE. They concluded that short term exposure to EMFs of mobile phones does not cause measurable immediate effects on the human auditory system.

Renzo R et al also conducted a similar study to assess the short term effects of mobile phone use on ear, assessed by transient evoked otoacoustic emissions and brainstem evoked audiometry response. The study parameters were similar to our study but they studied the short term effects of EMFs in contrast to our study where we tried to find the effects of long term exposure. They did not find any change in the auditory functions, before and after the short exposure to electromagnetic radiations.

Ozturan et al assessed transient evoked OAE and distorted product OAE in adults exposed to 10 min telephone call using GSM mobile phones. The tests were done before and after the exposure. They concluded that otoacoustic emissions did not change after the electromagnetic waves exposure.

Bamiou DE et al also reported that there was no change in the transient evoked otoacoustic emission, due to electromagnetic waves of mobile phones.

S Bhagat et al, studied the effects of chronic exposure to EMF emitted from mobile phone on inner ear by using distorted product otoacoustic emissions. Individuals using mobile phones for more than 4 years were studied. It was concluded that long-term and frequent exposure to EMFs from mobile phone does not cause damage to outer hair cells of cochlea.

P. Karthikeyan et al did a study on hundred students who were mobile phone users. They were divided into two groups of more than and less than two hours of mobile usage. DPAOE was done and compared to controls. Significant change in DPOAE was seen in cases, more so in group with more than two hours of cell phone usage.

Alsanosi AA et al did a study to assess the immediate consequences of 60 minutes exposure to mobile phones on hearing function by determining changes in distortion product otoacoustic emission (DPOAE) and hearing threshold levels (HTLs). They concluded that sixty minutes of close exposure to electromagnetic fields emitted by a mobile phone had an immediate effect on HTL assessed by pure-tone audiogram and inner ear (assessed by DPOAE) in young human subjects. Hearing Loss From Mobile Phone Use Essay

While in our study, on comparing DPOAE, we did not find any significant difference between the total cases and controls. On comparing the each sub group of cases to controls, no statistically significant difference was noted. This is in concurrence with most of the studies done in India and abroad. Though, P. Karthikeyan and Alsanosi have shown different results from those observed in our study.

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Though a lot of research publications are available in favour of and against the results observed in our study, but in all these studies studied the effects of electromagnetic frequencies of mobile phones on functioning of outer hair cells, but no criteria was taken as standard for comparison as different duration (in years) of exposure, different hours per day of use, and acute effect v/s chronic effects. The major limitation of epidemiological studies addressing the health effects of mobile phone use is related to exposure assessment. Also, other factors were not taken in account like exposure to noise, which is known to cause damage to outer hair cells much before any change in pure tone audiometry is seen (Anjali Desai et al, 1999) (RJ Salvi ea at, 2000). So, with all these factors nothing can be said with much certainty. Further research is needed to establish the effect of EMF on outer hair cells.

The present scientific evidences are insufficient to support the belief that there will be no ill effects on human health and the present safety standards are enough to protect users from ill effects, if any. This present situation of scientific uncertainty calls for the requirement of both precautionary measures and further research. Ill effects of mobile phone use on health might be of the field of interest for future research.

We conclude from our study that: mobile telephones should be used for short periods only, only for essential purposes, and unnecessary long conversation over mobile phones should be avoided. Hearing Loss From Mobile Phone Use Essay.