Occupational Hearing Loss

Occupational Hearing Hazard is a major public health concern as it is one of the most common occupational disorders worldwide. Occupational hearing loss develops due to exposure to loud noise or ototoxic chemicals at work. In most cases, hearing impairment is permanent, but further damage can be prevented with proper measures.

What is Occupational Noise-Induced Hearing Loss?

Occupational noise hazard depends on several factors, such as loudness, duration, and repetition. It is the second most common cause of adult hearing loss after presbycusis or age-related hearing loss, accounting for 16% of all cases. Chronic noise exposure can damage the cochlea that contains hair cells (specialized hearing cells).

According to the National Institute for Occupational Safety and Health, the average noise exposure level should not exceed 85 decibels (sound intensity) for an eight-hour workday. However, 25% of all employees are exposed to occupational noise above 85 decibels, and 53% of these loud workplace workers do not wear hearing protection. At-risk industries for hazardous noise include manufacturing, mining, and construction.    

What is Chemical-Induced Hearing Loss?

Hearing impairment can occur due to exposure to certain occupational chemicals, also called ototoxic chemicals. The most common agents affecting cochlea include solvents (e.g., toluene, xylene, trichloroethylene), metals (e.g., mercury, and lead), asphyxiants (e.g., carbon monoxide, hydrogen cyanide, and tobacco smoke), nitriles, and pesticides. The extent of hearing loss differs based on exposure frequency, quantity, and duration. Employees are exposed to these chemicals by breathing, consuming contaminated food, or absorbing them through the skin.

Ototoxic chemicals are often used in manufacturing, mining, oil and gas extraction, and agriculture. The effects of chemicals can be amplified if combined with noise exposure, resulting in a higher risk of hearing loss. About 10 million employees are estimated to be exposed to these chemicals.

 Impact of Occupational Hearing Hazards

Occupation hearing hazards mainly present with partial or complete hearing loss that develops gradually and mostly affects both ears. Noise-induced hearing loss increases the risk of dizziness and tinnitus, which is the subjective sensation of sound without any external source.

Hearing loss and tinnitus can compromise mental health, leading to a feeling of isolation, anxiety, and depression. It can also cause safety concerns, as people with impaired hearing are at higher risk of getting injured at the workplace. Pregnant women should avoid loud workplaces, as this can harm the child’s hearing.

Prevention of Occupational Hearing Loss

Various preventive measures can be taken to avoid occupational hearing hazards. Noise-induced hearing loss most effectively can be addressed by removing the sound source, substituting it with alternative equipment that makes less noise, placing barriers between employees and the hazard, reducing the duration and frequency of exposure, and using hearing protection devices. Exposure to ototoxic chemicals can be reduced by replacing them with less toxic substances, improving ventilation, training employees to handle chemicals safely, and using personal protective equipment such as gloves, eye protection, and masks.  

References

https://www.cdc.gov/niosh/topics/noise/about.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603754/

https://www.intechopen.com/chapters/75934