Smoking as a risk factor in noise-induced hearing loss

We studied the relationship between cigarette smoking and hearing loss among 2,348 noise-exposed white male participants in a hearing conservation program at an aerospace company. Comparisons of risk factors were based on two definitions of hearing loss. In the first, cases were defined as those subjects in the top third of the hearing loss distribution (at 3, 4, and 6 kHz) for their age category, and controls were those subjects in the lowest third of the distribution. The crude relative risks for smokers were significantly elevated (ever smoker: odds ratio = 1.27, p = .02; present smoker: odd ratio = 1.39, P = .002) compared with never smokers. Simultaneous evaluation of several risk factors using multiple logistic regression methods indicated that the effects of smoking, having a noisy hobby, and years worked at the plant were independent factors for hearing loss. Statistically significant trends in risk were observed for the number of pack-years of smoking (P = .007) and current packs per day consumption in present smokers (P = .009). In the second definition, hearing loss cases were defined according to National Institute for Occupational Safety and Health criteria for beginning impairment. By using multiple logistic regression, present smoking was a statistically significant independent predictor of impairment. These results suggest that smokers are at increased risk of noise-induced hearing loss.