Interaction between noise and cigarette smoking for the outcome of hearing loss among women: A population-based study

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. Am. J. Ind. Med. 56:1213-1220, 2013. (c) 2013 Wiley Periodicals, Inc.