Nicotine addiction and hearing loss in young subjects from Beirut, Lebanon

Abstract

Background: Many studies have established an association between cigarette smoking and Hearing Loss (HL) mostly in subjects working in noisy places. However, few studies are devoted to the relationship between environmental noise and smoking through nicotine addiction. Objectives: The present study aimed to examine the effect of nicotine dependence on hearing loss and its association with environmental (non-occupational) noise among young subjects in Beirut. Patients and Methods: The study recruited smokers (100) and non-smokers as a reference group (100) aged 21 to 50 years living in noisy or quiet areas of Beirut [70 to 90 A-weighted decibels (dBA)]. After filling out a questionnaire related to medical history and lifestyle risk factors, including smoking and exposure to noise, each volunteer was subject to a hearing assessment including otoscopy and screening pure-tone air. The incidence of hearing loss was defined as a pure-tone average of thresholds at 2000, 4000 and 8000 Hz greater than 25-dB hearing level in either ear. Smokers were referred to perform the Fagerstrom test for nicotine dependence. A saliva sample was also collected from all subjects for cotinine determination, a biomarker of exposure to tobacco smoke. Results: The obtained results showed that smoking is associated with hearing loss at 8000Hz after age 40. Current smokers are 1.73 times as likely to have hearing loss as nonsmokers (P < 0.05). Saliva cotinine levels were divided into three categories: group 1 (< 15 ng/mL), group 2 (16 - 75 ng/mL) and group 3 (76 - 125 ng/mL). The incidence of hearing loss in each group was, respectively, 13 %, 16% and 23% (P < 0.05). Conclusions: The significant difference between groups 1 and 3 permits to establish a correlation between degree of nicotine addiction and hearing loss. However, further studies are needed to identify the mechanisms leading to hearing loss.