Cigarette smoking and risk for hearing impairment: a longitudinal study in Japanese male office workers

The association of cigarette smoking with development of hearing impairment (loss of 30 dB at 1000 Hz and 40 dB at 4000 Hz) over a 5-year follow-up was studied in 1554 non-hearing-impaired Japanese male office workers who ranged in age from 30 to 59 years. After controlling for potential predictors of hearing impairment, the relative risk for low-frequency hearing impairment compared with never smokers was 1.12 (95% confidence interval [CI], 0.57 to 2.17) for ever-smokers, 1.21 (95% CI, 0.65 to 2.25) for current smokers of 1 to 20 cigarettes/day, 1.35 (95% CI, 0.70 to 2.61) for current smokers of 21 to 30 cigarettes/day, and 1.82 (95% CI, 0.98 to 3.38) for current smokers of 31 or more cigarettes/day (P for trend = 0.063). The respective multivariate-adjusted relative risks for high-frequency hearing impairment compared with never smokers were 1.70 (95% CI, 0.85 to 3.40), 1.82 (95% CI, 0.92 to 3.59), 2.00 (95% CI, 0.98 to 4.08), and 2.20 (95% CI, 1.09 to 4.42) (P for trend = 0.025). As the number of pack-years of exposure increased, the risk for high-frequency hearing impairment increased in a dose-dependent manner (P for trend = 0.011), but the risk for low-frequency hearing impairment did not (P for trend = 0.172). Our results indicate that cigarette smoking is highly associated with development of high-frequency hearing impairment in Japanese male office workers.