title: Interaction between noise and cigarette smoking for the outcome of hearing loss among women: a population-based study.
abstract: BACKGROUND
  We investigated the interaction between exposure to noise and smoking in relation to prevalence of hearing loss among women.
  
  
  METHODS
  A sample of women aged 20-49 years (n = 1,723) from a population-based cross-sectional study carried out in Brazil in 2006 was examined. Hearing loss was assessed using a yes-no validated question. Biological interaction was analyzed using the additive scale and measured with interaction contrast ratio (ICR) and assessment of dose-response relationship.
  
  
  RESULTS
  The combined effect of exposure to noise and cigarette smoking on hearing loss (adjusted prevalence ratio (PRadj) = 3.94, 95% confidence interval (CI): 2.81, 5.52) was greater than expected based on the additive single effects of smoking (PRadj = 1.39, 95% CI: 1.07, 1.81) and noise (PRadj = 2.66, 95% CI: 1.86, 3.82). ICR estimates were not statistically significant. The prevalence of hearing loss among noise-exposed women increased with duration of smoking (P trend = 0.026), number of cigarettes smoked per day (P trend = 0.034), cumulative tobacco use (P trend = 0.030), and early age at smoking initiation (P trend = 0.047).
  
  
  CONCLUSIONS
  Noise and smoking may have a combined effect on hearing loss but further studies are still needed. A dose-response relation of smoking for the noise effect among women is suggested.
authors.affiliation: Department of Hearing and Speech Sciences, Federal University of Bahia, Salvador, BA, Brazil. ferrite@ufba.br
authors.forename: Silvia
authors.initials: S
authors.lastname: Ferrite
authors.forename: Vilma S
authors.initials: VS
authors.lastname: Santana
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
mesh_terms: D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D034381:Hearing Loss / Q000453:epidemiology; D006317:Hearing Loss, Noise-Induced / Q000453:epidemiology*; D006801:Humans; D008875:Middle Aged; D009622:Noise; D009623:Noise, Occupational / Q000706:statistics & numerical data; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D055815:Young Adult
keywords: cross-sectional studies; noise-induced hearing loss; occupational health; smoking; women