Effects of cigarette smoking on the evolution of hearing loss caused by industrial noise

Abstract

The few studies evaluating the changes caused by cigarette smoking on hearing loss induced by occupational exposure to noise have reached discordant conclusions. The aim of this study is to investigate the interactions between cigarette smoking and occupational exposure to noise as risk factors in the onset and development of hearing loss. The study was performed on a sample of 557 shipyard workers exposed to noise at an Equivalent Level (Leq) of 93 dBA. On the basis of their smoking habits, they were divided into three groups: group (A), non-smokers; group (B), smokers (15-30 cigarettes per day); and group (C), heavy smokers (over 30 cigarettes per day). The study focussed on the audiometric responses of the subjects at the frequencies of 500, 1000, 2000, 3000 and 4000 Hz. The results were then compared using statistical techniquees (Internal correlation coefficient, exponential model, ANCOVA, NPC test). Comparison of the audiometric responses showed statistically significant differences between the three groups. Non-parametric analysis, performed using the NPC test, highlighted that the interaction between smoking and exposure to noise has an influence on hearing loss at all frequencies, and particularly at high frequencies (3000-4000 Hz). The data obtained from the examined sample show that smoking and exposure to noise cause an increase in occupational hearing loss and that this is directly related to the number of cigarettes smoked.