10-Year prospective study of noise exposure and hearing damage among construction workers.
OBJECTIVE
To characterise the effects of noise exposure, including intermittent and peaky exposure, on hearing damage as assessed by standard pure-tone thresholds and otoacoustic emissions, a longitudinal study was conducted on newly hired construction apprentices and controls over a 10-year period.


METHODS
Among the 456 subjects recruited at baseline, 316 had at least two (mean 4.6) examinations and were included in this analysis. Annual examinations included hearing threshold levels (HTLs) for air conducted pure tones and distortion product otoacoustic emission (DPOAE) amplitudes. Task-based occupational noise exposure levels and recreational exposures were estimated. Linear mixed models were fit for HTLs and DPOAEs at 3, 4 and 6 kHz in relation to time since baseline and average noise level since baseline, while controlling for hearing level at baseline and other risk factors.


RESULTS
Estimated L(EQ) noise exposures were 87±3.6 dBA among the construction workers. Linear mixed modelling demonstrated significant exposure-related elevations in HTL of about 2-3 dB over a projected 10-year period at 3, 4 or 6 kHz for a 10 dB increase in exposure. The DPOAE models (using L1=40) predicted about 1 dB decrease in emission amplitude over 10 years for a 10 dB increase in exposure.


CONCLUSIONS
The study provides evidence of noise-induced damage at an average exposure level around the 85 dBA level. The predicted change in HTLs was somewhat higher than would be predicted by standard hearing loss models, after accounting for hearing loss at baseline. Limited evidence for an enhanced effect of high peak component noise was observed, and DPOAEs, although similarly affected, showed no advantage over standard hearing threshold evaluation in detecting effects of noise on the ear and hearing.
Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98115, USA. nseixas@uw.edu
Noah S
NS
Seixas
Rick
R
Neitzel
Bert
B
Stover
Lianne
L
Sheppard
Patrick
P
Feeney
David
D
Mills
Sharon
S
Kujawa
D000328:Adult; D001309:Auditory Threshold; D060389:Construction Industry; D005260:Female; D006309:Hearing / Q000502:physiology; D006317:Hearing Loss, Noise-Induced / Q000209:etiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009622:Noise / Q000009:adverse effects*; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D017084:Otoacoustic Emissions, Spontaneous; D011446:Prospective Studies; D055815:Young Adult