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Collecting Data on Worker Hearing Loss: Epidemiology in Action

Posted on by Elizabeth Masterson, PhD, CPH, COHC
Epidemiology is the art and science of using data to answer questions about the health of groups. In occupational epidemiology, we use that data to understand how work affects health.  This blog entry is part of a series that shares the stories behind the data.

Hearing loss is one of the most common chronic health conditions in the United States. Among older adults, it is third after high blood pressure and arthritis. Nearly 1 in 4 cases of hearing loss among workers is caused by exposures on the job. These exposures include loud noise and chemicals that can damage hearing, such as organic solvents, heavy metals and asphyxiants.

To prevent more workers from losing their hearing, we need to know the size of the problem, identify the workers most at risk, and monitor trends in worker hearing loss for improvement. This requires epidemiological surveillance, which is collecting health-related information for analysis and dissemination to control or prevent disease or injury. The quality of the surveillance depends on the quality of the information collected.

Before our project, most of the surveillance estimates were based on information reported by individual workers, because worker hearing tests were largely unavailable for analysis. Unfortunately, when individuals have to judge the quality of their own hearing, they tend to underestimate how much difficulty they are having. The best way to determine if a worker has hearing loss is to perform a hearing test. Most U.S. workers exposed to loud noise on the job are required by government regulations to receive annual hearing tests, so large numbers of worker hearing tests exist.

 

This need for better surveillance data inspired our project.

In 2009, Drs. SangWoo Tak and Geoffrey Calvert came up with a method for obtaining large numbers of worker hearing tests, and the NIOSH Occupational Hearing Loss (OHL) Surveillance Project was born. We contacted the testing services who perform the worker hearing tests. These testing services include audiometric service providers, occupational health clinics, hospitals and others. We refer to them as data providers. The information the data providers shared with NIOSH included the hearing test results for each worker, and demographics of the worker such as age and gender. All the data shared with NIOSH had the personal information such as names and addresses removed to protect the identities of the workers and their employers.

So far, we have partnered with 18 data providers and collected about 9 million hearing tests for noise-exposed workers. These are longitudinal data, meaning that for many of the workers, we have multiple hearing tests conducted over time. We are continuing to collect this data.

 

What have we done with this information?

The industry for each worker’s hearing test was identified. We developed methods for analyzing the data to identify instances of hearing loss that were not likely to have been caused on the job.  This allowed us to produce estimates of the number of workers with occupational hearing loss (prevalence) for each U.S. industry and examine the risks, taking into account other factors like age and gender. We have disseminated this information in publications, newsletters, presentations, via Twitter and on the web.

We found that sub-sectors within the Mining, Construction and Manufacturing industries have the highest risks for hearing loss. This confirmed some previous research, but indicated a higher prevalence of affected workers; especially within Construction. The prevalence of workers with hearing loss in many of these industries is 24% or higher (30% in Highway, Street and Bridge Construction). A surprising result was that all industries have groups of workers with elevated risks for hearing loss, including Healthcare, Real Estate and Finance. There is no industry where workers are ‘safe’ from developing hearing loss on the job. Every worksite needs to identify exposed workers and protect them.

Please check out our newly updated web site that includes statistics, publications and other resources, and FAQs for data providers who want to partner with NIOSH on this project. Thank you!

 

Elizabeth Masterson, PhD, CPH, COHC

Dr. Masterson is an epidemiologist in the NIOSH Division of Surveillance, Hazard Evaluations and Field Studies.

Posted on by Elizabeth Masterson, PhD, CPH, COHC

8 comments on “Collecting Data on Worker Hearing Loss: Epidemiology in Action”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    I used to work in a laundry and the noise was unbearable there. And workers we could not bring earplugs because then not hear supervisors. Now I make websites and I am really happy.

    Your comment highlights a common objection to hearing protectors. Sometimes hearing protectors can “over-protect,” or block too much sound, making it hard to hear conversation. Choosing an ear plug which blocks less sound (lower attenuation) could be a solution. If a worker already has some hearing loss, using a ‘flat attenuation’ ear plug can make speech more understandable. Either type of ear plug can be purchased from most safety suppliers.

    The problem prevails very much in other countries, also. Prevention is possible. Enforce the local Factories Act (Eg. OSHA, HSE), strctly. Hearing loss can be due to exposing oneself to high volumemusic, etc. I attend music performances frequently. The drum (apercussion instrument) cause the maximum havoc. At times, I advice the manager of the sound system and even the organizers to maintain a volume that is just sufficient for everone to hear. But, they do not bother. They are afraid of the drummer! In fact, it is true. Recently, I had a bitter experience. On my advice, the volume was reduced. immediately, the drummer admonished the sound system superviser. Immediately, the original volume was restored. The only solution: Delare even venues like music halls as factories and enforce the laws regarding noise pollution. Automatically, the problem gets virtually vanished.
    Krishna Prasad.K.N. ES&H Consultant and Trainer, Mysore, India

    Most of all industries like real estate, machine work as well as Traffic police also have hearing loss problem. It is going to be very crucial in future on hearing loss for those who are working in this industry

    Dr. Masterson, you make a very good point about over protection and the related risks. I must disagree with using flat attenuation plugs when better tools are available.

    I have long been a proponent of thorough noise surveys that include dose measurement and octave band analysis. This used to be a time consuming practice but instruments have improved greatly making this a reasonable feat. Recently I learned about a Svantek dosimeter that performs octave band analysis with the dose measurement. I plan to buy a set soon and wondered if you have evaluated them due to the obvious advantage of octave band analysis over NRR.

    Would appreciate your thoughts.

    Thank you for your comment. Our comment regarding the flat-attenuation hearing protection was in response to a reader’s concern about communicating with his supervisor in a noisy laundry facility. NIOSH always recommends a thorough survey of the workplace noise environment. Octave-band analysis, while very useful for understanding the frequency spectrum and applying noise control measures, would not alleviate the need for that reader to use appropriate hearing protection such as the flat-attenuating earplugs that can protect his hearing and allow better communication between workers and with their supervisors. There are several capable and similar noise dosimeters on the market today, however NIOSH has not tested or evaluated them.

    This is great information and I really appreciate the research that has been done and compiled but is there new documentation out there that shows a potential decrease in NIHL to the following questions:

    1. How many workers are currently exposed to harmful noise annually?
    2. How many of those workers actually get an occupational OSHA required hearing screening?
    3. For employees that have a Standard Threshold Shift, how many go on to have a compensable hearing loss?

    Any help or direction to these questions is appreciated.

    1. How many workers are currently exposed to harmful noise annually?
    The current best estimate which uses 1999-2004 National Health and Nutrition Examination Survey (NHANES) data is that 22 million U.S. workers are exposed to hazardous noise each year. An analysis using 2014 National Health Interview Survey (NHIS) data is currently in review for publication.

    2. How many of those workers actually get an occupational OSHA required hearing screening?
    For questions regarding OSHA requirements for screening hearing in workers, please contact them directly. It is unknown how many noise-exposed U.S. workers are tested vs. not tested. Not all industries are mandated to test noise-exposed workers and some industries are regulated by other regulatory entities.

    3. For employees that have a Standard Threshold Shift, how many go on to have a compensable hearing loss?
    The processes for identifying/logging a recordable STS and filing workers compensation claims are not connected. One does not prompt the other. A worker may have an STS and not receive workers compensation, and vice versa. Workers compensation rules also vary among states.

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