Hearing Loss Isn't Always About Sound

Ototoxicity refers to the toxic effect of certain substances on the auditory system, leading to damage or loss of hearing. While exposure to ototoxic chemicals is a concern in various environments, the workplace poses a unique set of challenges due to the diverse range of substances employees may encounter. This essay explores the concept of ototoxicity, its impact on hearing, and highlights specific chemicals found in workplaces that can exacerbate hearing loss.

Ototoxicity primarily targets the delicate structures of the inner ear, such as the hair cells and auditory nerve. These structures are crucial for the process of hearing, and any damage can result in permanent hearing loss. Ototoxic substances can be pharmaceutical drugs, solvents, metals, and other chemicals commonly used in various industries. Let’s look at each of these ototoxic substances a little deeper.

Pharmaceutical Drugs.

Ototoxic pharmaceutical drugs, often used for medical treatment, can inadvertently cause harm to hearing. Examples include aminoglycoside antibiotics like gentamicin and certain loop diuretics. Healthcare professionals are particularly at risk due to their exposure to these medications.

Solvents.

Solvents, frequently found in industries like painting, printing, and cleaning, pose a significant risk of ototoxicity. Toluene, xylene, and styrene are examples of solvents known to harm hearing. Workers in these industries must be aware of the potential dangers and take appropriate precautions.

Metals.

Exposure to certain metals, such as lead and mercury, has been linked to ototoxic effects. Industrial processes involving metalwork, battery manufacturing, and metal smelting may expose workers to these harmful substances. Proper protective measures and regular monitoring are essential in such environments.

Asphyxiants.

Some chemicals, like carbon monoxide and hydrogen cyanide, which are prevalent in certain industrial settings, can indirectly lead to ototoxicity. These substances can compromise blood flow to the inner ear, resulting in damage to auditory tissues.

Pesticides.

Agricultural workers and those involved in pest control are susceptible to ototoxicity due to exposure to certain pesticides. Organophosphates and carbamates are examples of pesticides that have been associated with hearing loss.

The consequences of ototoxicity in the workplace are not well known among safety professionals. Individuals exposed to these harmful substances may experience a gradual decline in hearing ability, tinnitus (ringing in the ears), and even complete hearing loss. The severity of the impact depends on factors such as the duration and intensity of exposure, as well as individual susceptibility.

The measures taken to prevent the compounded hearing loss affects of ototoxic substances are much the same as what can be done for sound-related hazards. The key take-away is that – even if your sound and noise levels do not rise above the occupational safety and health administration (OSHA) and American Conference of Industrial Hygienists (ACGIH) permissible exposure limit or threshold limit values of 85 dB and 90db, respectively, it is important to take measures to protect your employees from hearing loss when ototoxic chemicals are or could be present in the work environment.

When ototoxic chemicals are present or when medical examination for fitness for duty reveals that pharmaceutical drugs are part of an employee’s daily regimen to manage underlying medical conditions, the following steps should still be taken:

• Wearing appropriate PPE, such as ear protection devices like earmuffs or earplugs, is crucial in workplaces where exposure to ototoxic substances is likely.

• Implementing engineering controls, such as ventilation systems and enclosed workspaces, can help minimize the spread of ototoxic substances in the air. This is particularly important in industries where solvents and chemicals are commonly used.

• Periodic audiometric testing for employees in high-risk occupations can detect early signs of hearing loss. Regular monitoring allows for timely intervention and prevents further damage.

• Workers should be educated about the potential hazards of ototoxic substances and trained on the proper use of protective measures. Employers play a crucial role in creating awareness and fostering a culture of safety in the workplace.

Which chemicals commonly found in the workplace environment have ototoxic effect? It is always important for you to do your own research, but here are some that I found during a quick search of published articles:

• Toluene

• Xylene

• Styrene

• Trichloroethylene

• Lead

• Mercury

• Arsenic

• Formaldehyde

• Acrylonitrile

• Ethylene oxide

• Carbon monoxide

• Organophosphates

• Carbon disulfide

• Nitrous oxide

• Manganese

In hearing protection program for the workplace, employers may need to conduct various tests and assessments to ensure the effectiveness of the program and protect the hearing health of their employees. Employers should conduct baseline hearing tests for all employees exposed to noise to establish their initial hearing status. Regular audiometric testing (at least annually) is required for employees exposed to noise to monitor any changes in hearing over time. Sound and noise monitoring is commonplace, along with mandatory employee training and education.

Other points of a hearing protection program include medical evaluations, regular task evaluations, comprehensive record keeping, and periodic evaluation of the effectiveness of the hearing protection program, including its components and the overall reduction in noise exposure. I suggest that ototoxicity of substances be one of the critical areas that all employers should include in their review before making decisions on the types of hearing protection and other measures put in place to protect employee hearing.

Ototoxicity in the workplace is a silent but significant threat to hearing health. Recognizing the types of chemicals that can exacerbate hearing loss and implementing preventive measures are essential steps in ensuring a safe working environment. Through a combination of education, monitoring, and the use of protective equipment, workplaces can minimize the risk of ototoxicity and promote the well-being of their employees. It is imperative for employers, employees, and regulatory bodies to work collaboratively to create and maintain a workplace where the soundscape remains a source of inspiration, not harm.

James A. Junkin, MS, CSP, MSP, SMS, ASP, CSHO is the chief executive officer of Mariner-Gulf Consulting & Services, LLC, the chair of the Veriforce Strategic Advisory Board and the chair of Professional Safety journal’s editorial review board. He is Columbia Southern University’s 2022 Safety Professional of the Year (Runner Up) and a much sought after master trainer, keynote speaker, podcaster (the Risk Matrix), and author of numerous articles concerning occupational safety and health.