title: The Effect of Occupational Noise Exposure on Blood and Biochemical Parameters: A Case Study of an Insulator Manufacturer in Iran.
abstract: BACKGROUND
  Occupational noise is among the most critical occupational hazards, which, in addition to hearing loss, can cause other adverse consequences on an individual's physical and mental health. Long-term exposure to noise can affect blood and biochemical parameters and subsequently lead to increased risk of cardiovascular disease. This study investigated the effect of occupational exposure to noise on blood and biochemical parameters of workers in an insulator manufacturing plant.
  
  
  METHODS
  This case-control study was conducted on workers in the production section (49 people as a case group) and the administrative staff (10 people as a control group) in one insulator manufacturing plant from 2010 to 2014. To assess individual exposure of workers to noise, the noise dosimeter model TES-1355 was used. Noise dosimetry testing was done based on the exposure pattern of workers to noise in compliance with the Iranian national standard (the criterion level of 85 dBA and the exchange rate of Q = 3 dBA). Blood parameters such as blood glucose, cholesterol, red blood cells (RBC), white blood cells (WBC), hemoglobin (Hb), and hematocrit (Hct) were studied in production workers (case) and administrative staff (control) over five consecutive years. The data were analyzed by software (SPSS-22) using the t-test, Mann-Whitney test, Fisher exact test, and Greenhouse-Geisser test.
  
  
  RESULTS
  No significant difference was found among the demographic data of the two groups (p > 0.05). Average of glucose and cholesterol levels in the two groups was statistically significant (p < 0.05) and blood glucose levels in the case group significantly reduced over time and cholesterol increased (p < 0.001). Mean difference of RBC number, WBC number, and serum levels of Hb and Hct was statistically significant between the two groups (p < 0.05). In addition, these hematological parameters increased among workers during these years.
  
  
  CONCLUSIONS
  Occupational exposure to noise may have a significant effect on an individual's blood parameters, which will cause harmful effects on worker health. Therefore, industrialists must take preventive measures in the field of noise control.
authors.affiliation: M.Sc. Student, Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hamzeh
authors.initials: H
authors.lastname: Mohammadi
authors.affiliation: Ph.D., Assistant Professor, Department of Occupational Health, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Iraj
authors.initials: I
authors.lastname: Alimohammadi
authors.affiliation: B.Sc. Student, Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Saman
authors.initials: S
authors.lastname: Roshani
authors.affiliation: Ph.D. Student, Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Pakzad
authors.affiliation: M.Sc., Department of Occupational Health, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Bagher
authors.initials: MB
authors.lastname: Abdollahi
authors.affiliation: Ph.D. Candidate, Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Somayeh Farhang
authors.initials: SF
authors.lastname: Dehghan
keywords: blood parameters; dosimetry; insulator; occupational exposure