Chemicals linked to hearing loss

Chemicals linked to hearing loss
While it’s well-known that work-related hearing loss usually is caused by noise, what isn’t nearly as widely-recognized is that ongoing exposure to some widely used chemicals increases the risk of hearing loss, particularly in noisy workplaces.

Yet, both animal experiments and human studies suggest that workers exposed to some chemicals suffer "ototoxic" effects – a fancy word scientists use to describe damage to both the hearing and balance functions of the ear.

Outside of laboratories, the human impact is being seen with growing frequency among workers at companies where noise and chemicals are part of daily life.

A small Ontario furniture manufacturer noticed three of its factory workers were suffering varying degrees of hearing loss. Working beside loud machinery combined with various chemicals used to produce finished furniture created a growing concern for the company. The firm became concerned about the potential harm the combination could have on impairing the hearing of its employees.

Although tests could not pinpoint the exact cause, noise and chemical exposure were found to be factors directly responsible for the employees’ hearing loss.

Wide-spread risks
When researchers looked at workplaces where there seemed to be a link between noise levels and chemicals, they found that the risks are wide-spread across industry. Some are obvious, such as for people who fuel large equipment, trucks and aircraft, those working in construction, manufacturing and metal works, and people who earn a living test firing weapons.

But many are surprisingly unexpected: Painters and printers are at risk as are boat builders, cabinetmakers and firefighters. As studies continue and more is learned about the deafening combination of noise and chemicals, the list of occupations where there is a potential problem keeps expanding.

Both businesses and government institutions are being warned of widely-used chemicals already known to cause possible hearing problems:
•    Benzene
•    Carbon disulfide
•    Carbon monoxide
•    Ethylbenzene
•    Hydrogen cyanide
•    Lead
•    Mercury
•    n-Hexane
•    Solvent mixtures
•    Styrene
•    Trichloroethylene
•    Toluene
•    Xylene

All of these are found in fuels and plastics, as thinners for paints, lacquers and dyes, in detergents, medicines, perfumes, fabric and paper coatings, printer’s ink, spray surface coatings and insect repellents.

Cut risks easily
A big Homer Simpson “D-Oh!” would be most people’s reaction to someone saying that the best way to reduce hearing loss risk is to cut workplace noise and exposure to “ototoxins.” But the fact is, doing so isn’t always possible or practical.

A more workable and highly cost-effective solution is ensuring that workplaces and employees are adequately protected with the right equipment and gear.

The fastest way to cut down the risk from noise is issuing disposable polyurethane foam earplugs or earmuffs. They’re made from a soft, low-pressure foam that is comfortable to wear because it exerts very little pressure on the ear canal. And they’re easy for compliance supervisors to check that workers are using them because they’re bright purple with yellow cord. The cord’s extended length allows for simple removal and makes the earplug more visible from a distance.

The second step is to have sound meters available throughout a plant. There are at least 10 different models available, many of which are portable so inspectors can move from one area to another, testing sound levels as they walk.

Plants are easily and inexpensively retrofitted with sound baffles as an additional safeguard around areas where noise is especially intense.

Beyond this, be sure to have a hearing conservation programme even for workers at lower levels of noise exposure than required by OSHA rules. Include workers exposed to chemicals in your hearing conservation programs, whether or not they are exposed to noise.

Isaac Rudik is a compliance consultant with Compliance Solutions Canada Inc., A Canadian provider of health, safety and environmental compliance solutions to industrial, institutional and government facilities. E-mail Isaac at or phone him at 905-761-5354.