Mercury Exposure in a Riverside Amazon Population, Brazil: A Study of the Ototoxicity of Methylmercury

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.

Hair as a Biomarker of Long Term Mercury Exposure in Brazilian Amazon: A Systematic Review

“…According to the year of publication, the articles were published as follows: three in 1998 [ 16 , 17 , 18 ], two in 1999 [ 19 , 20 ], three in 2000 [ 21 , 22 , 23 ], two in 2001 [ 24 , 25 ], one in 2002 [ 26 ], two in 2003 [ 27 , 28 ], four in 2005 [ 29 , 30 , 31 , 32 ], three in 2006 [ 33 , 34 , 35 ], two in 2007 [ 36 , 37 ], one in 2008 [ 38 ], one in 2009 [ 39 ], two in 2010 [ 40 , 41 ], three in 2012 [ 42 , 43 , 44 ], one in 2013 [ 45 ], one in 2014 [ 46 ], three in 2015 [ 47 , 48 , 49 ] and two in 2016 [ 50 , 51 ]. Most of the studies (61%) were performed exclusively by Brazilians Institution [ 16 , 18 , 20 , 21 , 22 , 24 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 37 , 41 , 42 , 43 ,…”

“…There was a predominance of studies that were performed in the State of Pará (47%) [ 22 , 23 , 25 , 26 , 27 , 29 , 35 , 36 , 37 , 38 , 39 , 40 , 42 , 43 , 45 , 47 , 48 ]. Some studies had been performed in the State of Amazonas (22%) [ 17 , 19 , 24 , 30 , 33 , 41 , 44 , 49 ], Rondônia (14%) [ 18 , 28 , 46 , 50 , 51 ], Mato Grosso (8%) [ 21 , 31 , 32 ] and Amapá (3%) [ 20 ]. Two studies were performed using samples from populations from two different States: Pará and Rondônia (3%) [ 16 ] and Rondônia and Amazonas (3%) [ 34 ].…”

Dietary nutrients and health risks from exposure to some heavy metals through the consumption of the farmed common carp (CYPRINUS CARPIO)

“…The general population is primarily exposed to heavy metal ions via food [ 23 ]. For instance, fishes are the major source of methylmercury and dental amalgam [ 19 ]. However, the general population does not face a significant health risk from methylmercury, although certain groups, especially with regional high fish consumption, may attain blood levels associated with a low risk of neurodegenerative abnormalities or damage [ 5 , 13 , 29 , 31 ].…”

Genetic Susceptibility to Neurodegeneration in Amazon: Apolipoprotein E Genotyping in Vulnerable Populations Exposed to Mercury

“…No correlation between mercury levels and age was found supporting the fact that age may not be an influencing factor for mercury exposure in adults. Accordingly, previous works already demonstrated no association between both factors in adults ( Hoshino et al, 2015 ; Arrifano et al, 2018b ), although it can be observed in children ( Barbosa et al, 1998 ; Pinheiro et al, 2007 ; Marques et al, 2016 ). Moreover, it is also relatively frequent to find higher mercury levels in men than those in women, usually attributed to a higher consumption of fish ( Dolbec et al, 2000 ; Fillion et al, 2006 ; Passos et al, 2007 ; Ashe, 2012 ), as we detected in our study.…”

“…Worryingly, several studies have demonstrated high mercury content in hair of some riverine populations in Amazon ( Berzas Nevado et al, 2010 ; Marques et al, 2013 ; Hacon et al, 2014 ; Hoshino et al, 2015 ; Arrifano et al, 2018b ). These communities are exposed mainly to methylmercury (MeHg) through consumption of contaminated fish ( Berzas Nevado et al, 2010 ; Rodriguez Martin-Doimeadios et al, 2014 ; Arrifano et al, 2018b ), as other vulnerable populations throughout the world ( Drescher et al, 2014 ; Strain et al, 2015 ; Langeland et al, 2017 ; Salazar-Camacho et al, 2017 ).…”