Abstract
Introduction Mercury poisoning causes hearing loss in humans and animals. Acute and long-term
exposures produce irreversible peripheral and central auditory system damage, and
mercury in its various forms of presentation in the environment is ototoxic.
Objective We investigated the otoacoustic emissions responses in a riverside population exposed
to environmental mercury by analyzing the inhibitory effect of the medial olivocochlear
system (MOCS) on transient otoacoustic emissions (TEOAE).
Methods The purpose of the research was to evaluate the entire community independently of
variables of sex and age. All of the participants were born and lived in a riverside
community. After otolaryngologic evaluation, participants were received tympanometry,
evaluation of contralateral acoustic reflexes, pure tone audiometry, and recording
of TEOAEs with nonlinear click stimulation. Hair samples were collect to measure mercury
levels.
Results There was no significant correlation between the inhibitory effect of the MOCS, age,
and the level of mercury in the hair.
Conclusions The pathophysiological effects of chronic exposure may be subtle and nonspecific
and can have a long period of latency; therefore, it will be important to monitor
the effects of mercury exposure in the central auditory system of the Amazon population
over time. Longitudinal studies should be performed to determine whether the inhibitory
effect of the MOCS on otoacoustic emissions can be an evaluation method and diagnostic
tool in populations exposed to mercury.
Keywords
mercury - methylmercury compounds - auditory pathways - medial olivocochlear system
- otoacoustic emissions - ototoxicity
