title: The Use of the Kurtosis-Adjusted Cumulative Noise Exposure Metric in Evaluating the Hearing Loss Risk for Complex Noise.
abstract: To test a kurtosis-adjusted cumulative noise exposure (CNE) metric for use in evaluating the risk of hearing loss among workers exposed to industrial noises. Specifically, to evaluate whether the kurtosis-adjusted CNE (1) provides a better association with observed industrial noise-induced hearing loss, and (2) provides a single metric applicable to both complex (non-Gaussian [non-G]) and continuous or steady state (Gaussian [G]) noise exposures for predicting noise-induced hearing loss (dose-response curves).
  
  
  
  Audiometric and noise exposure data were acquired on a population of screened workers (N = 341) from two steel manufacturing plants located in Zhejiang province and a textile manufacturing plant located in Henan province, China. All the subjects from the two steel manufacturing plants (N = 178) were exposed to complex noise, whereas the subjects from textile manufacturing plant (N = 163) were exposed to a G continuous noise. Each subject was given an otologic examination to determine their pure-tone HTL and had their personal 8-hr equivalent A-weighted noise exposure (LAeq) and full-shift noise kurtosis statistic (which is sensitive to the peaks and temporal characteristics of noise exposures) measured. For each subject, an unadjusted and kurtosis-adjusted CNE index for the years worked was created. Multiple linear regression analysis controlling for age was used to determine the relationship between CNE (unadjusted and kurtosis adjusted) and the mean HTL at 3, 4, and 6 kHz (HTL346) among the complex noise-exposed group. In addition, each subject's HTLs from 0.5 to 8.0 kHz were age and sex adjusted using Annex A (ISO-1999) to determine whether they had adjusted high-frequency noise-induced hearing loss (AHFNIHL), defined as an adjusted HTL shift of 30 dB or greater at 3.0, 4.0, or 6.0 kHz in either ear. Dose-response curves for AHFNIHL were developed separately for workers exposed to G and non-G noise using both unadjusted and adjusted CNE as the exposure matric.
  
  
  
  Multiple linear regression analysis among complex exposed workers demonstrated that the correlation between HTL3,4,6 and CNE controlling for age was improved when using the kurtosis-adjusted CNE compared with the unadjusted CNE (R = 0.386 versus 0.350) and that noise accounted for a greater proportion of hearing loss. In addition, although dose-response curves for AHFNIHL were distinctly different when using unadjusted CNE, they overlapped when using the kurtosis-adjusted CNE.
  
  
  
  For the same exposure level, the prevalence of NIHL is greater in workers exposed to complex noise environments than in workers exposed to a continuous noise. Kurtosis adjustment of CNE improved the correlation with NIHL and provided a single metric for dose-response effects across different types of noise. The kurtosis-adjusted CNE may be a reasonable candidate for use in NIHL risk assessment across a wide variety of noise environments.
authors.affiliation: 1Institute of Environmental and Occupational Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China; 2Auditory Research Laboratories, State University of New York at Plattsburgh, Plattsburgh, New York, USA; 3Battelle Centers for Public Health Research and Evaluation, Seattle, Washington, USA; 4Center for Disease Control and Prevention of Huzhou, Huzhou, China; and 5Center for Clinical Epidemiological Research, Peking University Third Hospital, Beijing, China.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Xie
authors.forename: Wei
authors.initials: W
authors.lastname: Qiu
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Heyer
authors.forename: Mei-Bian
authors.initials: MB
authors.lastname: Zhang
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Zhao
authors.forename: Roger P
authors.initials: RP
authors.lastname: Hamernik
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000453:epidemiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D066192:Manufacturing Industry; D000072499:Manufacturing and Industrial Facilities; D008875:Middle Aged; D009623:Noise, Occupational; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D018570:Risk Assessment; D013232:Steel; D013783:Textile Industry; D055815:Young Adult
chemical_list: D013232:Steel