Collecting Data on Worker Hearing Loss: Epidemiology in Action

Categories: Epidemiology, Hearing Loss, Safety and Health Data

December 3rd, 2014 10:46 am ET - 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