I’m Wearing My Hearing Protection – Am I Still At Risk for Hearing Loss? Lurking Ototoxins in the Military Environment

Abstract

Objective Information is summarized from the overall body of published literature regarding ototoxic chemicals encountered outside of clinical exposures, largely in occupational settings. While summarizing the most common non-pharmaceutical ototoxins, this review provides clinically relevant information and recommendations such that hearing health professionals may adopt a more comprehensive and appropriate diagnostic case history, test battery, documentation scheme, and education delivery. Methods Solvents, metals, and asphyxiants literature was reviewed using PubMed, national and international agency websites, and communications with known ototoxicity experts. Results Initial intentions to summarize the existing programs for occupational ototoxicity monitoring fell short when it was discovered that such programs have not yet formalized across the major oversight agencies in the United States. Instead, recommended guidance documents and fact sheets, which highlight existing occupational exposure limits and suggest monitoring and education are discussed. Conclusions While evidence in humans is limited, potentially ototoxic substances are worthy of improved surveillance and further research to understand their ototoxic mechanisms, effects, and possible mitigation strategies. A triad approach of monitoring, protecting, and educating is recommended for effective prevention of hearing loss: the Department of Defense Hearing Center of Excellence’s Comprehensive Hearing Health Program model employs such an approach.

Prevention and Management Intervention (PMI) of Occupational Ototoxic Exposure in Industrial Perspective Globally: A Systematic Review

“…Another approach involves conducting a risk assessment for the combination of noise and ototoxic chemical exposure. European countries in the European Noise Directive indicated that the interactions of noise with other risks (ototoxicants) must be given special consideration by the employer by conducting a risk assessment (24) The statement is in accordance with previous studies that suggested even though noise levels are below the legal limit, workers are still encouraged to wear hearing protection equipment while exposed to noise and ototoxicants concurrently (16)(17)23). Similarly, the Spanish transposition of the Noise Directive has clearly stated that ototoxicity could be prevented by controlling exposure using a suitable PPE while being exposed to the ototoxicants (32).…”

“…There were 16 selected full text items consisting of eight (n=8) published articles (16)(17)(18)(19)(20)(21)(22)(23) and eight (n=8)…”

“…In this review, 14 out of 16 (88%) selected items specifically focused on exposure risk reduction and control. The risk reduction and control approaches mentioned include [1] conducting risk assessment (4, 21-24), [2] wearing personal protective equipment (PPE) (4,16,17,23), [3] reducing exposure limit of chemical exposure (17,23,27) and noise exposure (28), [4] audiometry monitoring (4,17,18,20,(22)(23)(24)(26)(27)(28)(29)(30), and [5] adding a "Noise notation" to the Threshold Limit Values (TLV) (19,27).…”

“…Of the selected items, 31% (n=5) suggested clinical assessments including the test battery approach (20), Otoacoustic Emissions (OAE) test (17,22,23), air conduction pure tone audiometry (without masking) (17,30), assessment of the loss of communication skills (17,22), middle-ear testing (22), extended high-frequency audiogram (17,23), as well as electrophysiological and/ or central auditory processing (CAP) screening tests (23).…”

“…Removing the source of risk via engineering controls, limited exposure time, and use of personal protective equipment is deemed the most effective means of avoiding hearing loss from noise or chemical exposure in the workplace (22). Previous studies also claimed that risk management strategies aimed at decreasing ototoxicants exposure should be encouraged and the personal protective equipment used by the workers exposed to ototoxicants need to be evaluated (11,23).…”