title: Cohort study for the effect of chronic noise exposure on blood pressure among male workers in Busan, Korea.
abstract: OBJECTIVE
  It has not yet been established whether exposure to chronic noise induces an increase in blood pressure or an increase in the development of hypertension. Therefore, a cohort study was performed to identify the effects of chronic noise exposure on blood pressure.
  
  
  METHODS
  Five hundred thirty male workers at a metal manufacturing factory in Busan, Korea, were enrolled in the study. They were monitored with an annual health check-ups for nine consecutive years from 1991 to 1999. The subjects were divided into four groups which were determined by noise level categories (NLCs) according to the exposure of noise intensity; NLC-I: office workers who were exposed to <60 dBA at work; NLC-II: worksite technical supporters or inspectors who were intermittently exposed to noise and were not using hearing protection devices; NLC-III: worksite workers exposed to a noise below 85 dBA (TWA) and used one type of hearing protection device, earplug or earmuff; NLC-IV: worksite workers who were exposed to a noise level of 85 dBA or higher in average and used both earplug and earmuff.
  
  
  RESULTS
  After controlling the possible confounders, such as baseline age, smoking, alcohol intake, exercise, family history of hypertension, systolic blood pressure (SBP), or diastolic blood pressure (DBP), and changes in body mass index (BMI), we determined that the mean values for the SBP over the duration of this study were 3.8, 2.0, and 1.7 mmHg higher in groups NLC-IV, NLC-III, and NLC-II, respectively, in comparison to that of the NLC-I group. There was no significant difference in DBP among the groups.
  
  
  CONCLUSIONS
  This study suggests that chronic noise exposure increases SBP independently, among male workers.
authors.affiliation: Department of Occupational and Environmental Medicine, Ulsan University Hospital, Dong-Gu, Ulsan, South Korea. chungang@dreamwiz.com
authors.forename: Ji Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Weechang
authors.initials: W
authors.lastname: Kang
authors.forename: Seung Rim
authors.initials: SR
authors.lastname: Yaang
authors.forename: Nari
authors.initials: N
authors.lastname: Choy
authors.forename: Choong Ryeol
authors.initials: CR
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001794:Blood Pressure; D015992:Body Mass Index; D016022:Case-Control Studies; D015331:Cohort Studies; D003971:Diastole; D004430:Ear Protective Devices / Q000706:statistics & numerical data*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000209:etiology*; D007723:Korea; D008297:Male; D008875:Middle Aged; D009623:Noise, Occupational / Q000009:adverse effects*; D009765:Obesity / Q000150:complications; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D013599:Systole; D055815:Young Adult