Manufacturing

Burden

An estimated prevalence of noise exposed workers in the manufacturing sector is nearly 6 million workers (37%) based upon National Health and Nutrition Examination Survey (NHANES) data [Tak et al. 2009]. To further understand the burden of hearing loss, NIOSH has partnered with hearing conservation providers to collect audiometric data from a broad spectrum of sectors. The burden for hearing loss among noise-exposed workers in the manufacturing sector was about 20% [Masterson et al. 2015]. Noise exposures are typically described as continuous, intermittent and impulsive. Occupational exposure limits have been developed assuming that the exposures are for continuous noise exposures over the course of a lifetime of exposure. Impulsive noise exposures or combinations of continuous noise and impulsive noise pose an increased risk of hearing loss [Davis et al. 2009; Zhao et al. 2010].

Exposures to noise in combination with solvents potentially poses an increased risk of hearing loss because the solvents can affect the auditory system through different mechanisms than the mechanical or metabolic destruction of the sensory hair cells [Johnson and Morata 2010]. The number of workers in the Manufacturing sector that experience mixed exposures is not well known and further surveillance research is needed to characterize the risk.

Need

While the general trend has been one of decline in the incidence of hearing loss in the manufacturing sector (a 2% reduction from 1986–2010), additional research and dissemination efforts are needed [Masterson et al. 2015]. Exposures to impulse noise represent a greater risk for early onset of hearing loss [Zhao et al. 2010; NIOSH 2016] and the interventions to prevent hearing loss from impulse noise have not been assessed for their effectiveness. A better understanding of risk factors (impulse noise, aging, and other agents) is needed. Specific needs include updated guidelines towards these risk factors and the incorporation of new technologies within hearing prevention loss programs, such as the integration of fit testing. A range of new hearing protector technologies has been brought to market in recent years and methods to evaluate their protection against impulse noise is necessary. Among these are devices with Bluetooth™, active noise cancellation, and near field communication capabilities. Research is needed to provide assessment and promotion of new technologies that can affect the field of hearing conservation.

Surveillance research is needed to better characterize noise exposures and hearing loss prevalence, especially among chemical, petroleum, and metal industries within the manufacturing sector. Surveillance research might include using new data sources for surveillance purposes, using existing methods to surveil a new population for which there is limited or no applicable surveillance data, or adding new questions to an existing survey like the National Health Interview Survey that target a population, exposure or outcome. Additionally, workplace noise exposures for targeted Manufacturing Sector tasks should be studied to characterize the noise dose, use/non-use of hearing protection and other personal protective equipment, and assessment of hearing conservation programs.

Burden

Within the manufacturing sector, 22%–55% of workers are exposed to hazardous noise (depending on sub-sector), and between 13% and 39% of these noise-exposed workers report not wearing hearing protection [Tak et al. 2009]. Noise-exposed manufacturing workers in electrical machinery, non-electrical machinery and textiles have the highest prevalence of not using hearing protection [Tak et al. 2009]. Many workers may have an elevated or disproportionate risk, including foreign-born workers and workers with limited English-language skills, workers in small businesses, contingent workers, and younger (teenage) and older (65 and over) workers [Themann et al. 2013].

Need

The 2017 Cochrane systematic review has identified a lack of demonstrated effectiveness for hearing conservation programs with regards to reducing the incidence of noise induced hearing loss [Tikka et al. 2017]. Interventions to prevent hearing loss are sometimes ineffective due to improper and inconsistent use of hearing protection coupled with inadequate training [Voix and Laville 2009; Byrne et al. 2017]. Employers and workers would benefit from education about noise, including the proper way to insert foam ear plugs, “Buy Quiet” programs, ways to reduce vibration of equipment to possibly reduce noise, and use of administrative controls to limit exposure to hazardous noise, as specified by OSHA requirements that allow for various exposure time/noise intensity levels [OSHA 2011].

Some hearing protection manufacturers now provide hearing protector fit-testing systems that can measure a Personal Attenuation Rating of hearing protectors which provide opportunities to aid in the proper selection of hearing protection. Translational research for fit testing methods is needed. In addition, hearing protection researchers and advocates should communicate with employers and employees about new smartphone-based noise metering apps [Kardous and Shaw 2015; Roberts et al. 2016]. Use of these tools will create an awareness of noise exposures, leading to steps to limit or reduce exposure to noise hazards.