Effect of Deliberate Ingestion of Organophosphate Pesticide on Distortion Product Oto-Acoustic Emissions (DPOAE)

Background: Oto-Acoustic Emissions (OAE) are low intensity sounds produced by the cochlea in response to an acoustic stimulus. Deliberate self-poisoning has become an increasingly common response to emotional distress in young adults (NHS, 1998). Organophosphate (OP) compounds are most commonly involved in 76% of pesticide poisoning especially in the developing countries like India. Several pesticides are neurotoxin which could potentially affect hearing and, animal studies showed that OP treatment leads to change in hearing threshold, outer and inner hair cell loss but human studies on the same are very few. Aim: The present study was aimed at exploring the cochlear changes after self-poisoning with OP pesticides by measuring the Distortion Product Oto-Acoustic Emissions (DPOAE). Method: 114 subjects were participated in the study, with an age range of 18-30 years having pure tone audiometric thresholds within the normal limits and no history of middle ear pathology. They were further divided into two groups, I and II which includes self-poisoned and healthy subjects respectively. Results: The “pass” and “fail” criteria of DPOAE measures in group I were 30% and 70% respectively whereas in group II, it was found 91% and 9% respectively. Discussion: There was a significant failure in DPOAE in Group I (subjects who were self-poisoned) compared to group II (healthy subjects). The two important pathologies behind OP toxicity are the generation of Reactive Oxygen Species and the depletion of NADPH which is necessary for normal function. Conclusion: The results of the present study highlight that; the minute cochlear changes caused due to pesticide poisoning can be effectively measured through DPOAE. Further it can suggest in other clinical targets like Ototoxicity, Noise-induced hearing loss, Meniere’s disease etc., which has an effect on cochlear hair cells can be monitored through DPOAE.