by Fred R. Caron, CSP
Hearing loss is usually insidious, occurring gradually over a long period of time. It can be temporary or permanent based on the type of hearing loss. Hearing loss happens so gradually the person affected usually does not notice it until conversations become difficult, especially in situations where background noise is occurring. It can also happen instantaneously such as during an incident like an explosion or sharp blow to the head.
Causes of Hearing Loss
Typical industrial hearing loss can be caused by long term exposure to loud noises and sometimes exacerbated by a combination of loud noises and exposure to certain chemicals on the job such as toluene, xylene, n-hexane, organic lead, mercury and others [see Occupational Ototoxins (Ear Poisons) and Hearing Loss for more information]. While not much research has been conducted on the combination, many Industrial Hygienists and Industrial Audiologists have arrived at this conclusion.
Noise induced hearing loss can also be caused by exposures in settings other than industrial or work related experiences. For instance, loud music at concert settings has been found to be as high as 120 decibels which exceeds allowable OSHA/WISHA noise standards. Off the job noise can also be contributed to by wood cutting with power saws, which typically can exceed 105 decibels. Because of this, many companies encourage their employees to take ear plugs home for use.
Hearing loss sometimes occurs slowly as people age. This condition is known as presbycusis (pronounced prez-buh-KYOO-sis). Doctors do not know why presbycusis occurs, but it seems to run in families. More information on genetic types of hearing loss can be found in “Genetics Crash Course” from the Summer 2012 issue of Hearing Health Magazine.
Another reason for hearing loss may be exposure to too much loud noise. This condition is known as “noise-induced hearing loss.” Many construction workers, farmers, musicians, airport workers, tree cutters, and people in the armed forces have hearing problems because of too much exposure to loud noise. Sometimes loud noise can cause a ringing, hissing, or roaring sound in the ears, called tinnitus (pronounced tin-NY-tus).
Hearing loss can also be caused by a virus or bacteria, heart conditions, stroke, head injuries, tumors, and certain medicines such as aspirin. In addition, there are some surprising medical causes of hearing loss such as diabetes or hypertension. More information can be found in the Spring 2012 issue of Hearing Health Magazine.
Hearing Safety in the Washington State Workplace
Many companies conduct pre-hire and annual hearing testing to look for work related noise induced hearing loss and to ensure compliance with federal and state requirements for workplace safety and health standards that require annual testing and evaluation.
The Washington Industrial Safety and Health Act, sometimes referred to as WISHA, enforced by the Department of Safety and Health (DOSH), has Washington Administrative Codes (WAC) that require companies to conduct annual hearing testing when employees are exposed to over 85 decibels on an eight hour time weighted average basis (TWA8). These programs are designed to find Standard Threshold Shifts (STS).
Some of the applicable WAC codes are listed below:
WAC 296-817-40010: Establish a baseline audiogram for each exposed employee.
Conduct a baseline audiogram when an employee is first assigned to work involving noise exposures that equal or exceed 85 decibels TWA8.
- Make sure this audiogram is completed no more than 180 days after the employee is first assigned. -OR-
- Make sure employee is covered by a hearing protection audit program (as described by WAC 296-817-500 and available as an alternative only for employees hired for less than one year).
Note: Employers who utilize mobile test units are allowed up to one year to obtain a valid baseline audiogram for each exposed employee. The employees must still be provided training and hearing protection as required by this chapter.
Note for Oregon readers: Oregon did not adopt this exemption for mobile vans. In addition, no allowance may be made for presbycusis in determining STS in Oregon.
- Make sure employees are not exposed to workplace noise at least 14 hours before testing to establish a baseline audiogram. Hearing protectors may be used to accomplish this.
- Notify employees of the need to avoid high levels of non-occupational noise exposure (e.g., loud music, headphones, guns, power tools, motorcycles, etc.) during the 14-hour period immediately preceding the baseline audiometric examination.
- Conduct annual audiograms for employees as long as they continue to be exposed to noise that equals or exceeds 85 decibels TWA8.
Each annual audiogram should be examined by a person trained in reviewing audiograms. When hearing loss reductions of 10 decibels or more at 4,000, 5,000, and 6,000 Hertz from the Baseline audiogram occurs, it is considered a STS. This change becomes the new Baseline for annual audiogram comparisons.
The Standard also requires recording the STS on the OSHA 300 log as a work related illness, if the loss exceeds the age corrections as defined in the Standard. Most audiometric software is programed to compare all the data and give an age adjusted reading, so it is readily apparent when an STS is required to be recorded on the OSHA Log.
The Standard also allows a retest with-in 30 days to verify the shift. Most STSs go away upon retesting.
While not required by the Standard, it is a good idea to have a Hearing Conservation Counseling session with the employee who has had a STS that is potentially recordable. This session should be used to explain the many causes of hearing loss, to verify the correct usage of hearing protection devices, and to establish for the record if the employee has had a history of any hearing problems, medical or otherwise.
Employees suffering industrial noise induced hearing loss may be eligible for disability award from their respective State Industrial Insurance entities. While the criteria for compensable noise induced hearing loss is entirely different from the criteria used to determine STSs, the STS can be an early indicator of a potential compensable hearing loss developing over time.
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Download this paper in PDF (3 pages) here: 2015-04-28 Hearing Conservation Considerations