Ototoxicity – When Chemicals (yes, chemicals) Cause Hearing Loss
Let iSi help you determine what to do about ototoxic chemicals and noise exposures at your facility!The effects of chemical exposures in the workplace h...
The effects of chemical exposures in the workplace has been highly documented. Chemicals can affect you when you breathe them in, ingest them, inject them or absorb them through your skin. However, did you know that chemicals can cause hearing loss too?
⚡ TL;DR: Ototoxic chemicals (toluene, styrene, xylene, carbon monoxide, mercury, lead) combined with noise create hearing damage far worse than either exposure alone—even at noise levels below OSHA’s PEL. The synergistic effect is permanent. ACGIH recommends audiograms for combined exposures; many facilities miss this hazard entirely.
What is Ototoxicity? Chemicals which can contribute to hearing loss are called “ototoxicants” and the hearing loss itself is considered to be “ototoxicity.” Ototoxic chemicals reach the inner ear, connected pathways and nerve fibers through the blood stream or through the ear’s hair cells.
⚠️ Why This Matters: Hearing losses can range from sound distortion to complete inability to detect certain frequencies. The real problem: combined ototoxic chemical + noise exposure creates damage exponentially worse than either exposure alone—and the damage is permanent. Most facilities track noise exposure OR chemical exposure, but not the dangerous combination. Workers often don’t notice early symptoms until hearing loss is irreversible.
Ototoxic chemicals make a bigger impact on noise exposure, especially impulse noise. The noise levels do not even need to be above OSHA’s Permissible Exposure Limit (PEL) standards. It’s the combination of the two which causes the greatest damage. Which Chemicals Are Considered Ototoxic? Pharmaceuticals: aspirin, some antibiotics, NSAIDs, loop diuretics Tobacco smoke Solvents, degreasers and paints containing toluene, p-xylene, styrene, ethylbenzene, methylstyrene, trichlorethylene, carbon disulfide, n-propylbenzene or n-hexane Carbon monoxide Hydrogen cyanide Nitriles: 3-butenenitrile, cis-2-pentenenitrile, acrylonitrile, cis-crotononitrile and 3,3’-iminodipropionitrile Metals and compounds: mercury, lead, organic tin and germanium dioxide Pesticides: pyrethroids, hexachlorobenzene, insecticides or organophosphates Some limited research has also speculated arsenic, cadmium, halogenated hydrocarbons, bromates, alkylic compounds and manganese may also affect ototoxicity Which Industries or Operations May be Affected? Manufacturing Construction Printing Painting Fueling vehicles and aircrafts Firefighting Weapons firing (Military) Pesticide spraying How Do You Test for Otoxicity? Determining whether you have the potential for this condition is primary. First, conduct a risk assessment to determine if your operations could be affected. Check the Toxological Information section of the chemical’s Safety Data Sheet (SDS Section 11) to see if the chemical is considered a neurotoxicant. If there is nothing listed in this section, often other clues can be found in the SDS such as general toxicity, nephrotoxicity or if the chemical produces reactive free radicals. From there, exposure limits and thresholds are dependent on different factors such as the chemical itself, exposure routes, concentration, duration, noise exposure and individual risk factors such as age. Workplace sampling will be able to help you quantify your exposures. Audiogram tests can show early onset of hearing impairments and threshold shifts. However, they cannot tell you the difference between whether the impairment is noise-related or ototoxic-related. If you have complaints of hearing loss, investigate whether ototoxicity could be a factor. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends periodic audiograms for those who have noise exposures combined with carbon monoxide, hydrogen cyanide lead and solvent mixtures. When there’s not a noise exposure, ACGIH still recommends audiograms be used when workers have the potential to be exposed to ethylbenzene, styrene, toluene or xylene. PPE and Training Requirements Make sure you reduce the effects of ototoxic chemicals in your workplace either through controls such as isolation, limiting exposures, or eliminating unnecessary tasks, or through the use of PPE. Conduct your PPE assessment per OSHA rules. You may need to include proper hearing protection, as well as PPE which can prevent inhalation (respirators), or absorption through the skin (chemical gloves, arm sleeves, aprons). If you have a potential for ototoxic chemical exposure, this also needs to be included in your Hazard Communication (HAZCOM) training. Does This Affect You? Do you have the potential for ototoxicity in your workplace? iSi can help you make that determination, conduct your risk assessment, and/or quantify your exposures through sampling. Contact us today! Contributing: Ryan Livengood International Hazardous Materials Logistics Manager | EHS Regulatory Trainer As a former corporate environmental, health and safety manager, Ryan has a vast experience in working with both environmental and safety compliance issues in multiple states. His specialties include national and international dangerous goods transportation, hazardous waste, environmental compliance, industrial hygiene and safety compliance. He is also an ISO 14001 Lead Auditor. Email t
Frequently Asked Questions
Q: What is ototoxicity and which chemicals cause it?
A: Ototoxicity is hearing loss caused by chemical exposure, where ototoxic chemicals reach the inner ear through the bloodstream or hair cells. Common ototoxic chemicals include toluene, styrene, xylene, carbon monoxide, hydrogen cyanide, mercury, lead, and certain pharmaceuticals like aspirin and loop diuretics. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends periodic audiograms for workers exposed to these substances.
Q: How does ototoxic chemical exposure combine with noise to increase hearing damage?
A: Ototoxic chemicals amplify the effects of noise exposure, creating greater hearing damage than either exposure alone would cause. This synergistic effect occurs even when noise levels are below OSHA’s Permissible Exposure Limit (PEL). The combination of ototoxic chemical and noise exposures is particularly damaging to hearing in operations like painting, solvent handling, and manufacturing.
Q: Which industries and operations face ototoxicity risks?
A: Manufacturing, construction, printing, painting, aircraft fueling, firefighting, pesticide spraying, and military weapons operations all present ototoxicity risks. Any facility using solvents, degreasers, paints, carbon monoxide, or other ototoxic chemicals combined with noise exposure should conduct a risk assessment.
Q: How can employers assess and control ototoxicity hazards?
A: Employers should review the Toxicological Information section of Safety Data Sheets (Section 11) for ototoxicity warnings, conduct risk assessments combining chemical and noise exposure, perform workplace exposure sampling, and implement controls through isolation, substitution, or appropriate PPE including hearing protection and respirators.
💰 Hearing Loss Liability: OSHA’s recordkeeping rules require reporting of occupational hearing loss cases. Each case can trigger investigation and citations. Beyond compliance, workers’ compensation claims for occupational hearing loss can cost $50,000–$100,000+ per worker over a lifetime. A single identified case of ototoxic-related hearing loss in a facility with 20 exposed workers signals potential citations for all of them.
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