A re-examination of risk estimates from the NIOSH Occupational Noise and Hearing Survey (ONHS)

Abstract

This paper describes a new analysis of data from the 1968-72 National Institute for Occupational Safety & Health (NIOSH) Occupational Noise and Hearing Survey (ONHS). The population consisted of 1172 (792 noise-exposed and 380 "controls") predominately white male workers from a cross section of industries within the United States. The analysis focused on how risk estimates vary according to various model assumptions, including shape of the dose-response curve and the amount of noise exposure among low-noise exposed workers (or controls). Logistic regression models were used to describe the risk of hearing handicap in relation to age, occupational noise exposure, and duration exposed. Excess risk estimates were generated for several definitions of hearing handicap. Hearing handicap is usually denoted as an average hearing threshold level (HTL) of greater than 25 dB for both ears at selected frequencies. The frequencies included in the biaural averages were (1) the articulation-weighted average over 1-4 kHz, (2) the unweighted average over 0.5, 1, and 2 kHz, and (3) the unweighted average over 1, 2, and 3 kHz. The results show that excess risk estimates for time-weighted average sound levels below 85 dB were sensitive to statistical model form and assumptions regarding the sound level to which the "control" group was exposed. The choice of frequencies used in the hearing handicap definition affected the magnitude of excess risk estimates, which depended on age and duration of exposure. Although data were limited below 85 dB, an age-stratified analysis provided evidence of excess risks at levels ranging from 80 to 84 dB, 85-89 dB, and 90-102 dB. Due to uncertainty in quantifying risks below 85 dB, new data collection efforts should focus on better characterization of dose-response and longitudinal hearing surveys that include workers exposed to 8-hour time-weighted noise levels below 85 dB. Results are compared to excess risk estimates generated using methods given by ANSI S3.44-1996.

The global burden of occupational noise‐induced hearing loss

“…Also, the highest risk is found at the highest levels of exposure. Prince et al (1997) found a small increase in excess risk in workers exposed to 80 -84 dBA versus the < 80 dBA control group; however, these risk estimates are imprecise due to low numbers of workers in the study exposed to noise at these levels.…”

“…Excess risks for hearing loss >25 dBA resulting from moderately high and high noise exposure were taken from an article by Prince et al (1997) based on U.S. data, and adjusted to match the definition of hearing loss used by WHO, i.e., > 41 dBA. Relative risks were estimated from excess risks using data on background hearing loss at given ages taken from England (Davis, 1989).…”

Exposures to pharmaceutical dust at a mail order pharmacy - Illinois.

“…The notch from occupational noise can occur between 3,000 and 6,000 Hz [ACOM 1989;Osguthorpe and Klein 2001]. However, it is generally accepted that a notch at 4,000 Hz indicates occupational hearing loss [Prince et al 1997]. An individual may have notches at different frequencies in one or both ears [Suter 2002].…”

Health hazard evaluation report: HETA #2006-0196-3036, Liberty Veterinary Hospital, Liberty Township, Ohio.

“…17,18 It is generally accepted that a notch at 4000 Hz indicates occupational hearing loss. 19 On the other hand, some researchers have argued that the notch at 6000 Hz may not be a good marker for occupational hearing loss because it is widely seen in young adults and others with little documented occupational noise exposure. 20 An individual may have notches at different frequencies in one or both ears.…”