A cohort of over 450 construction apprentices and unexposed graduate student controls was enrolled and assessed annually for hearing damage over the past five years. Results demonstrated small but significant reductions in Distortion Product Otoacoustic Emissions (DPOAEs) in relation to hearing protection-adjusted noise exposure, especially around 4 kHz. We propose to continue studying approximately 300 cohort members who have had at least two previous examinations for noise exposure and hearing damage by measuring air conduction hearingthreshold levels (HTL.s) and DPOAEs. An additional five years of evaluation of the early progression of noise-inducechearing damage among young construction workers exposed to high but variable noise levels, and prospective documentation of the relationship between DPOAEs and standard HTLs, will provide much greater quantification of the risk and development of Noise-Induced Permanent Threshold Shift (NIPTS). We will enhance our previous efforts by improving the accuracy of both hearing damage assessment and noise exposure estimation, while collecting data that is consistent with our previous efforts. Annual examinations will include standard audiometry, wide-bandeminence acoustic reflex (AR), and DPOAEs, including a DP-Gram with L1=65 dB and I/O growth functions at 2, 3, 4 and 6 kHz. We will include audiometric testing with a 2 dB stepsize in order to improve the resolution of the measuremfjnt. AR measurement will allow for consideration of the AR as a potential modifier of NIPTS risk. DPOAE measurements will be collected using an improved protocol, and DPOAE I/O functions will be modeled using a segmented regression technique for better estimation of a DPOAE 'threshold'. Exposure estimation will continue using a task-basedapproach, but will be enhanced by obtaining activity and task updates from subjects quarterly, improving the specificity of task and tool definitions, and asking subjects to subjectively rate each of their exposures with reference to expectedlevels for the specific task. Sub-studies will be conducted to quantify the effectsof each of these methodological changesand ensure continuity with the first five-year study. By continuing to follow this cohort, we will obtain much-needed data concerning the natural history of early noise-induced hearing loss and the potential use of DPOAEs as markers of early hearing damage and predictors of later hearing loss. Continued prospective study of this established and well- characterized cohort of construction workers is a unique opportunity to further our understanding of NIPTS, arid to identify potential approaches to hearing lossprevention.

Agency
National Institute of Health (NIH)
Institute
National Institute for Occupational Safety and Health (NIOSH)
Type
Research Project (R01)
Project #
5R01OH003912-09
Application #
7435246
Study Section
Safety and Occupational Health Study Section (SOH)
Program Officer
Frederick, Linda J
Project Start
1999-09-30
Project End
2010-08-31
Budget Start
2008-09-01
Budget End
2009-08-31
Support Year
9
Fiscal Year
2008
Total Cost
$434,442
Indirect Cost
Name
University of Washington
Department
Public Health & Prev Medicine
Type
Schools of Public Health
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Feeney, M Patrick; Stover, Bert; Keefe, Douglas H et al. (2014) Sources of variability in wideband energy reflectance measurements in adults. J Am Acad Audiol 25:449-61
Seixas, Noah S; Neitzel, Rick; Stover, Bert et al. (2012) 10-Year prospective study of noise exposure and hearing damage among construction workers. Occup Environ Med 69:643-50
Neitzel, R L; Daniell, W E; Sheppard, L et al. (2011) Evaluation and comparison of three exposure assessment techniques. J Occup Environ Hyg 8:310-23
Neitzel, Richard L; Stover, Bert; Seixas, Noah S (2011) Longitudinal assessment of noise exposure in a cohort of construction workers. Ann Occup Hyg 55:906-16
Neitzel, Richard L; Daniell, William E; Sheppard, Lianne et al. (2011) Improving exposure estimates by combining exposure information. Ann Occup Hyg 55:537-47
Griffin, Stephanie C; Neitzel, Richard; Daniell, William E et al. (2009) Indicators of hearing protection use: self-report and researcher observation. J Occup Environ Hyg 6:639-47