Ototoxins & Hearing Loss: Are You at Risk?

The majority of workers suffer from hearing loss due to excessive and sustained noise in the workplace. Approximately 22 million people are exposed to decibels that can cause damage each year, according to the Centers for Disease Control and Prevention (CDC). Occupations such as working on an airport tarmac, operating a jackhammer, managing sound in a live music venue, or driving a semi-truck negatively impact inner ear structures.

For the purposes of this discussion, let’s pivot away from the leading cause of preventable hearing loss and consider another health and well-being threat. Can chemicals cause hearing loss?

It may come as a surprise, but the CDC lists chemical-related hearing loss directly after prolonged exposure to sounds of 85 dBA or higher. In fact, 13.7 million are reportedly at risk of ototoxic chemical exposure.

What are Ototoxic Chemicals?

Ototoxic chemicals possess the ability to penetrate the outer ear and damage fragile structures of the inner ear. They can directly affect portions of the inner ear or pass through the bloodstream, damaging neural pathways, sensory receptors, and hair cells. These are three types of ototoxic chemicals that are prevalent in the workplace.

• Neuro Toxicants:These substances have the capacity to inflict damage on the nervous system. They can interrupt and damage nerve cells beyond repair. Whether naturally occurring or manufactured, neurotoxicants penetrate the body through inhalation, skin contact, or ingestion. Common examples of industrial ototoxins include toluene, n-hexane, and heavy metals like lead, mercury, manganese, arsenic, and cadmium.
• Cochlear Toxicants:As their name implies, this class of substances affects hearing. Exposure to certain pesticides (organophosphates, carbamates), asphyxiants (carbon monoxide, hydrogen cyanide), heavy metals, and topical ointments can lead to tinnitus and gradual or abrupt hearing loss. Other examples include solvents such as styrene, xylene, trichloroethylene, and carbon disulfide.
• Vestibular Toxicants: This type of toxicant negatively impacts the vestibular system, which is responsible for maintaining our balance and spatial orientation. Along with heavy metals such as lead and mercury, industrial solvents, antibiotics, and chemotherapy drugs have a harmful effect on the equilibrium. Jet fuel, like JP-8, is a common industrial vestibular toxicant.

It’s important for workers and safety supervisors to keep in mind that mild exposure to ototoxic chemicals may make staff members more vulnerable to noise-related inner ear damage.

Even when an environment does not exceed the Occupational Safety and Health Administration (OSHA) permissible time-weighted average limit of 85 dBA over eight hours, employees may be at significant risk if ototoxins are used or created from processes in the work environment.

What Industries Use Ototoxic Chemicals?

Chemical-related hearing loss continues to plague industries that do not recognize the threat. Many fail to provide workers with the personal protective equipment (PPE) and clothing needed to prevent skin and ear contact, as well as inhalation. Sectors that utilize ototoxic chemicals in high-decibel environments heighten the risk of hearing loss, tinnitus, and debilitating equilibrium conditions like vertigo.

• Agricultural: Farm hands are considered a high-risk group regarding health and safety risks. Farming typically exposes workers to pesticides, fertilizers, solvents, and naturally occurring heavy metals. The ototoxic chemicals pose a substantial risk due to common skin contact, inhalation, and ingestion.
• Construction: Commonly used agents such as paint, thinners, degreasers, adhesives, tobacco smoke, diesel fuel, and the mercury in solder make construction sites an inherently dangerous environment.
• First Responders: Firefighters and other first responders enter disaster scenes in which chemical spills and combustion put them in harm’s way. Splatters and airborne particle inhalation create potentially dangerous ototoxic chemical conditions.
• Manufacturing: This catch-all category includes metal fabrication, oil refineries, textiles, clothing, equipment, automotive, boat/ship building, and solar panels, among many others. Workers routinely encounter heavy metals, solvents, and petroleum.
• Mining:Along with wide-reaching chemical solvents, mining operations expose workers to carbon monoxide and hydrogen cyanide.

It’s essential to point out that these and other industries normally produce loud noises. Safety managers would be well served to provide employees with ear-related PPE and disposable clothing that prevents skin contact and inhalation.

Health Effects of Ototoxic Chemical Exposure

Although the most notable health condition associated with ototoxins is chemical-related hearing loss, there are varying degrees of this condition and others. Given that inner ear health and functionality impact a wide range of processes, it’s not surprising that ototoxic chemicals can have such a profound effect on health and wellness. These are ways that exposure negatively impacts everyday people.

Chemical-Related Hearing Loss and Related Conditions

Prolonged or intense exposure to ototoxic chemicals can have varying effects on auditory abilities. These range from minor decreases in hearing to deafness.

• High-Frequency Hearing Loss: Workers may lose the ability to recognize higher-frequency sounds.
• Speech Dysfunction: Ototoxicity can render individuals incapable of distinguishing between sounds, particularly when multiple noises are at play.
• Compressed Loudness: Some sounds may seem much louder than they actually are.
• Frequency Identification: Noises of similar frequency may be rendered indistinguishable.
• Temporal Confusion: A byproduct of chemical-related hearing loss, people may lose their ability to recognize the timing of sounds.
• Spatial Identification: Those suffering from ototoxic chemical exposure may struggle to accurately pinpoint a noise’s origin.
• Dizziness: Depending on exposure level and other factors, light-headedness and dizziness can be temporary or persistent. They can range from mild to debilitating.
• Instability: The equilibrium can be impacted to such a degree that standing upright and walking require assistance.
• Motion Sickness: Those who are exposed to this class of chemicals are more likely to suffer from carsickness, airsickness, and seasickness.

Ringing in the ears, known as tinnitus, balance problems, and understanding the gist of conversations may also prove problematic. That’s largely because ototoxic chemicals can also bring about cognitive decline.

How are Workers Exposed to Ototoxic Chemicals?

There are three primary ways that people working in industrial, commercial, and agricultural landscapes are exposed to ototoxic chemicals. These include inhalation, ingestion, and skin contact. These are ways those health hazards usually happen in the workplace.

• Inhalation: Employees breathe in the fumes from solvents and liquid chemical agents. In some cases, particles are released by burning.
• Ingestion: Although less common than other ways to contract an ototoxic chemical condition, contaminated food and beverages remain a threat.
• Skin Absorption: Chemical splatters are a leading cause of chemical-related ailments in the workplace. Employers are tasked with following OSHA regulations that require distributing PPE and disposable clothing that resist chemical splatter and seepage.

What PPE is Recommended for Handling Ototoxic Chemicals?

Given that chemical-related hearing loss can result from direct contact and become more pronounced when coupled with loud noises, ear protection remains of paramount importance. Hard plastic earmuffs with sound-dampening capabilities rank among the best solutions. It’s also feasible to deploy earplugs in combination with chemical-splatter deterrents and the following items.

• Chemical Resistant Coveralls: Disposable personal protective coveralls must protect against direct skin contact and resist liquids soaking through quickly.
• Head Protections: Coveralls with hoods protect the scalp as well as the ears.
• Eye Protections: Face shields and protective goggles are necessary to keep liquids, smoke, and fumes from harming workers’ eyes.
• Respiration: Depending on the hazard and ventilation controls, workers may be required to use breathable masks. In particularly hazardous situations, respirators may be a necessity.
• Gloves: Workers need disposable gloves that protect their hands from chemical agents. They must be disposed of properly to prevent hand-to-face touching.
• Shoe Coverings: Unless industry-rated rubber boots are issued, disposable protective footwear coverings may prove necessary.

Employers are tasked with providing ongoing education and training to ensure employees follow strict health and safety regulations. Providing literature, company policies, and in-depth knowledge about how PPE and disposable clothing solutions help avoid unnecessary ailments, injuries, and ototoxic chemical hearing loss.