The Adverse Effects of Heavy Metals with and without Noise Exposure on the Human Peripheral and Central Auditory System: A Literature Review.

Marie-Josée Castellanos,Adrian Fuente

doi:10.3390/ijerph13121223

Abstract

Exposure to some chemicals in the workplace can lead to occupational chemical-induced hearing loss. Attention has mainly focused on the adverse auditory effects of solvents. However, other chemicals such as heavy metals have been also identified as ototoxic agents. The aim of this work was to review the current scientific knowledge about the adverse auditory effects of heavy metal exposure with and without co-exposure to noise in humans. PubMed and Medline were accessed to find suitable articles. A total of 49 articles met the inclusion criteria. Results from the review showed that no evidence about the ototoxic effects in humans of manganese is available. Contradictory results have been found for arsenic, lead and mercury as well as for the possible interaction between heavy metals and noise. All studies found in this review have found that exposure to cadmium and mixtures of heavy metals induce auditory dysfunction. Most of the studies investigating the adverse auditory effects of heavy metals in humans have investigated human populations exposed to lead. Some of these studies suggest peripheral and central auditory dysfunction induced by lead exposure. It is concluded that further evidence from human studies about the adverse auditory effects of heavy metal exposure is still required. Despite this issue, audiologists and other hearing health care professionals should be aware of the possible auditory effects of heavy metals.

Highlights

Heavy metals such as lead, mercury and arsenic are present in the environment in many forms: as a soil component, water contaminant, dust particle in urban areas [1], and in many others
It has been consistently shown that low as well as high exposure levels to heavy metals have an adverse effect on human health, leading to conditions such as cardiovascular and pulmonary dysfunctions [7,8]
Abnormalities in auditory brainstem response (ABR) latencies induced by lead exposure have been shown to occur in rhesus monkeys [12]

Summary

Introduction

Heavy metals such as lead, mercury and arsenic are present in the environment in many forms: as a soil component, water contaminant, dust particle in urban areas [1], and in many others. Heavy metals are widely present in a number of industrial sectors including mining and construction and millions of workers are potentially exposed to these agents in the workplace [6]. It has been consistently shown that low as well as high exposure levels to heavy metals have an adverse effect on human health, leading to conditions such as cardiovascular and pulmonary dysfunctions [7,8]. Some studies have shown an association between exposure to heavy metals and hearing disorders in animals [9,10]. Abnormalities in auditory brainstem response (ABR) latencies induced by lead exposure have been shown to occur in rhesus monkeys [12]. Ozcaglar et al [13] found in rats an adverse effect of cadmium

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