Why Ototoxic Chemicals are as Dangerous as Loud Noises

Ototoxicity refers to the toxic effect of certain substances on the auditory system, leading to hearing damage or loss. While exposure to ototoxic chemicals is a concern in various environments, the workplace poses unique challenges because of the many substances employees may encounter.

This article explores the impact of ototoxic chemicals on hearing and highlights specific chemicals found in workplaces that can worsen hearing loss.

What Does Ototoxicity Do?

Ototoxicity primarily targets the delicate structures of the inner ear, such as the hair cells and auditory nerve. These structures are crucial for hearing; damage can result in permanent hearing loss. Ototoxic substances can be pharmaceutical drugs, solvents, metals, and other chemicals commonly used in various industries.

Top 5 Ototoxic Chemicals

1. 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.

2. Solvents

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

3. Metals

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

4. Asphyxiants

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

5. 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 associated with hearing loss.

The Impacts of Ototoxicity

The impact of ototoxicity in the workplace remains relatively unknown among safety professionals. Workers exposed to these harmful substances may gradually notice:

• A decline in their ability to hear
• Persistent ringing in their ears (known as tinnitus),
• And in some unfortunate cases, complete hearing loss.

The severity of these effects depends on several factors, including how long and intensely a person was exposed and their susceptibility to ototoxic substances.

Ototoxicity Prevention

When preventing the compounded effects of hearing loss due to ototoxic substances, the approach mirrors what we do for noise-related hazards. The key takeaway here is that even if your workplace doesn’t reach or exceed the permissible exposure limits set by regulatory bodies like OSHA and ACGIH—where noise levels should stay below 85 dB and 90 dB, respectively—it’s still crucial to take proactive measures to safeguard your employees from potential hearing loss when they might encounter ototoxic chemicals on the job.

When ototoxic substances 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 company should take the following steps:

1. Ensuring workers wear appropriate PPE, such as ear protection devices like earmuffs or earplugs, is crucial in workplaces where exposure to ototoxic substances is likely.
2. Implementing engineering controls, such as ventilation systems and enclosed workspaces, can help minimize the spread of ototoxic substances in the air.
3. Perform audiometric testing for employees in high-risk occupations to detect early signs of hearing loss. Regular monitoring allows for timely intervention and prevents further damage.
4. Educate workers about the potential hazards of ototoxic substances and train them on properly using protective measures. Employers are crucial in creating awareness and fostering a workplace safety culture.

Knowing the most common toxic chemicals in a workplace environment is also critical. That list includes the following:

• Toluene
• Xylene
• Styrene
• Trichloroethylene
• Lead
• Mercury
• Arsenic
• Formaldehyde
• Acrylonitrile
• Ethylene oxide
• Carbon monoxide
• Organophosphates
• Carbon disulfide
• Nitrous oxide
• Manganese

Key Tests and Assessments

When creating a hearing protection program for the workplace, employers have a vital role in safeguarding their employees’ hearing health. Several tests and assessments may be necessary to ensure the program’s effectiveness, which should include the following:

Baseline Hearing Tests and Procedures

Employers should conduct baseline hearing tests for all employees exposed to noise. These tests establish their initial hearing status, providing a reference point for future assessments.

Regular Audiometric Testing

Regular audiometric testing should be a standard practice for employees exposed to noise, occurring at least annually. This ongoing monitoring helps detect any changes in hearing over time.

Sound and Noise Monitoring

Monitoring sound and noise levels in the workplace is crucial. This information informs decisions about protective measures and helps maintain compliance with safety regulations.

Employee Training and Education

Mandatory training and education programs ensure that employees understand the risks of noise exposure and the proper use of protective measures.

Additional elements of a comprehensive hearing protection program include medical evaluations, regular task assessments, thorough record-keeping, and periodic evaluations to gauge the program’s overall effectiveness.

Employers must prioritize considering ototoxic chemicals in their review of hearing protection measures. Ototoxicity is a significant yet often overlooked threat to hearing health in the workplace. Employers can create a safer working environment by recognizing the chemicals that can contribute to hearing loss and taking preventive measures.

Collaboration among employers, employees, and regulatory bodies is paramount in maintaining a workplace where the soundscape remains a source of inspiration rather than harm. Connect with us to find out how Veriforce can help ensure a safer workplace for everyone.

Contact us today to learn more.

About the Author

James A. Junkin, MS, CSP, SMS, ASP, CSHO is the chief executive officer of Mariner-Gulf Consulting & Services, LLC and 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, and author of numerous articles concerning occupational safety and health.