Upwardly mobile: Lowered hearing?

The mobile phone is not just a “good old instrument” for communication. It has insinuated into nearly every aspect of human activity. However, like any useful amenity, the potential for misuse exists. The blame for a number of social and health hazards has been laid at the door of the mobile phone. While some in the former category are undeniably true, direct health issues are yet to be unequivocally proven. At the same time, it must be kept in mind that the mobile phone provides socioeconomic benefits too.[1] Hence, a blanket ban is out of the question. Coming to the topic at hand, the ear becomes the chief target organ of this assault of the mobile phone, in the form of noise, electromagnetic radiation (EMR) and heat. Needless to say, the effects of this assault must be studied, by the preventive medicine and otology/audiology fraternity. As such, the present research study by Das et al. is a commendable effort.[2]

A look at basic sciences tells us that mobile phones use EMR in the microwave range (450–2100 MHz). The interaction between electromagnetic fields and living tissue constitutes what is called as “bioelectromagnetics.” This has been an active area of study, although a lot of gray area still persists. Biological phenomena in animals have been proven. Thermal and behavioral effects in humans have been reported. However, direct evidence of harm to human health has not been forthcoming. After the explosion of mobile phone use in the present age, there has been no dearth of research trying to swing the discourse to either side. Among the many negative effects reported has been that on semen quality and male fertility in rats.[3] There has also been everyone's favorite bugbear – carcinogenicity (brain tumors). At the same time, vehement denial of any significant harm on humans has also been documented. In this context, it is interesting to note the conclusion arrived at in one study:[4] “Studies funded exclusively by industry reported the largest number of outcomes but were least likely to report a statistically significant result. The interpretation of results from studies of health effects of radiofrequency radiation should take sponsorship into account.”

Many studies have been undertaken all over the world with objectives more or less similar to the present one. And, with very few exceptions, most have revealed the deleterious effect on hearing, to a greater or lesser extent. The methodologies adopted reveal an attempt to study the spectrum of usage of different types of mobile phones. In this context, I have a few concerns with the methodology adopted for this study. First of all, was the objective to study the effects of only EMR on the cochlea? In which case, that should be specified. It need not be a given that it is only EMR that is “under the scanner,” so to speak. Does the effect of noise not matter? It has been calculated that the maximum volume of a smartphone can reach concert-hall levels (around 105 decibels). Even if a reckless youngster employs some moderation in intensity, the duration would be an issue. Needless to say, this has a proven deleterious effect on the cochlea, separate from that of EMR. Should that also not be factored while doing such studies? It must also be pointed out at this juncture that studies have not conclusively proven the harmful effects of EMR on the cochlea.[56] Be that as it may, literature search reveals that most studies have focused on EMR exposure. Next, the cutoff of 2 h for the duration of individual mobile phone use seems arbitrary. It would probably have been worth classifying into more groups, namely, <2 h, 2–4 h, and so on. This could have brought out the effects of duration of use in a better way. One Indian study has adopted this method.[7] Having said that, the researchers must be commended for meticulous selection of the study group, especially the handedness aspect. Furthermore, the choice of medical students is an apt one, as there is some evidence of overuse of mobile phones in this population.[8]

Specific absorption ratio has been mentioned in passing; it is an important aspect of the measure of EMR exposure. The stated value in the study is in the acceptable range, as per the Federal Communications Commission.[9] One study has commented on the need for separate normatives for children.[10]

From the results, it is interesting, and probably heartening, to note that nearly half the included students’ usage of mobile phones was <2 h. This could probably be due to the location of the study (Sikkim). Would it be much different if it were in the bigger towns and metros of India, one wonders! The proof of the pudding is in the eating: In this study, statistical proof of prolonged phone use affecting the hearing threshold in the (ab) used ear has been forthcoming. Hence, kudos to the research team for achieving this end. The other noticeable thing is that there is no particular worsening at 4000 Hz – indicating an absence of noise-induced hearing loss.

So what is the solution? The much-neglected cliche holds true in the present context too: Prevention is better than cure. The WHO has recommended the voluntary adoption of the “precautionary principle.” An interesting study has looked at the effect of people's knowledge about this.[11]

To conclude, keeping in mind the demographic of our country, where we have a burgeoning young, upwardly mobile population, with ever increasing “nomophobia,” there is a definite need to map the effect of this “necessary evil.” Hence, studiesuch as the present one are to be encouraged as a means to prevent a potential epidemic of early hearing disability. Overall, this study should be replicated in as many medical colleges in India as possible. And, to go a step further, my suggestion would be a cohort study to follow a group of mobile users over a period to check for worsening hearing, and possibly a prospective study taking into account the level of exposure to radiation.