Certain Chemicals May Cause Hearing Loss

Certain Chemicals May Cause Hearing Loss

What are Ototoxicants and What Damage Do They Do?

Strange as it may seem at first, ototoxicants are chemicals that when inhaled, ingested, or absorbed through the skin can cause hearing loss and issues with one’s balance. Certain medications may come with such a risk, but most frequently it is in the workplace where one is exposed to such chemicals. The employee may or may not even be aware of the exposure and its associated risks, but either way, the choice to take such a risk or not is most likely beyond their control. 

Common examples of such chemicals include some varieties of pesticides, metals, and solvents. Whether there has been any exposure to potentially damaging noise or not, one’s ability to register quiet sounds can be impacted, as can the clarity of audible sounds. This decreased clarity can cause speech discrimination dysfunction, the ability to discern voices from environmental noise. Symptoms of speech discrimination dysfunction may include:

  • distortion: the compression of loudness
  • the inability to distinguish between sounds of similar frequencies
  • temporal resolution: trouble recognizing the intervals between sounds
  • spatial resolution: trouble localizing sounds

It is easy to understand how speech discrimination dysfunction

can exacerbate the dangers of already risky work environments with difficulty hearing coworkers, warning signals, and environmental cues. The damage done by ototoxicants may be mild or severe, temporary or permanent. But how is such damage possible, you may be asking yourself? 

Ototoxicants damage your central auditory system. This will likely be simpler to understand when we first consider the industries which come with greater risks of such exposure and the potential damage each may cause. 

Industries and Risks 

  • Agricultural workers risk exposure through pesticides and herbicides which they are likely to inhale when it is being sprayed or to absorb through their skin when they touch the soil or crops.
  • Construction workers risk exposure due to their frequent use of solvents. Also known as VOCs (volatile organic compounds), solvents dissolve and dilute other substances and are commonly present in paint, paint strippers, thinners and glues.
  • The utilities industry maintains distribution and delivery of natural gas, electricity and water, and oversees the removal of sewage. Each of these specific services requires habitual proximity to plenty of potentially dangerous chemicals.
  • Dangerous fumes and residues are common byproducts of many sub-sectors of the manufacturing industry, for example fabricated metal workers, or apparel and textile workers.
  • Mining is the industry with the single highest rate of noise induced hearing loss. Miners are exposed to dangerous volumes for extended periods every day. But many elements of the residue of the work are also hazardous, illustrating the complexity of measuring the exact degrees to which various factors cause damage.

How Ototoxicants are Categorized

Ototoxicants are categorized in two different ways. Depending on which part of the ear that gets the brunt of the injury, ototoxicants are classified as neurotoxicants, cochleotoxicants, or vestibulotoxicants. 

  • Neurotoxicants damage the nerve fibers that interfere with hearing and balance.
  • Cochleotoxicants affect cochlear hair cells, which are the minuscule sensory receptors at the root of all hearing.
  • Vestibulotoxicants injure the hair cells of the balancing systems, an example of why one may commonly become dizzy after inhaling a dangerous chemical.

The Occupational Safety andHealth Administration (OSHA) groups ototoxic chemicals into five categories.

  • Pharmaceuticals, including certain analgesic painkillers and antibiotics
  • solvents
  • asphyxiants, including tobacco smoke and carbon monoxide
  • nitriles
  • metals and compounds, including Mercury and lead

Risk Mitigation Measures

Obviously many of the industries that present these risks are at the very core of how we organize our society andour comforts. But of course the potential risk to each individual worker must be reduced as much as possible. The majority of this responsibility falls on the industries more than the individuals and their compliance with OSHA’s guidelines. 

OSHA offers five basic steps to limit exposure to ototoxicants.

  1. Review the Safety Data Sheet that lists specific toxicological warnings. Knowledge and the ability to identify risks are the obvious first steps. 
  2. Eliminating ototoxicants and substituting ototoxical chemicals with less toxic chemical at every possible opportunity.
  3. When elimination or substitution are not possibilities, isolation and enclosures are critical. Ventilation, for example, will make a tremendous impact lessening the threat of airborne materials.
  4. Behavioral shifts such as eliminating unnecessary tasks that involve ototoxicants or noise exposure, and limiting exposure time can reduce risks.
  5. Personal protective equipment (PPE) such as lab coats, safety glasses/goggles, gloves, etc must follow protocols without exception.

Constant vigilance to these simple guidelines can make all the difference in one’s hearing health and overall potential quality of life. Researchers do know that ototoxicant chemical exposure and noise in combination do synergistic damage. This means that in especially unsafe work environments in which both risks are present, both elements—the noise and the chemicals—can both be below permissible exposure limits and still cause lasting damage. 

Hearing tests cannot distinguish between ototoxicant-induced hearing loss and noise induced hearing loss. But, they can help determine whether a hearing loss is present and whether you might benefit from treatment. Contact us today to schedule a hearing test!