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 (n¼1,723) from a population-based cross-sectional study arried 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)¼3.94,95% confidence interval (CI): 2.81,5.52) was greater than expected based on the additive single effects of smoking (PRadj¼1.39, 95% CI: 1.07, 1.81) and noise (PRadj¼2.66, 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 ¼0.026), number of cigarettes smoked per day (Ptrend ¼0.034), cumulative tobacco use (Ptrend¼0.030), and early age at smoking initiation (P trend ¼0.047). Conclusions: Noise and smoking may have a combined effect on hearing loss but fur- ther studies are still needed. A dose–response relation of smoking for the noise effect among women is suggested.