勞工耳毒有機溶劑及噪音暴露與聽力損失之相關性探討

Association of Exposure to Ototoxic Organic Solvents and Noise with Hearing Loss Among Workers.

職業性聽力損失為國內主要職業病之一，危險因子包括職場噪音、耳毒性物質使用、振動、聲震等。國內雖已規定作業環境噪音音壓級及工作日容許暴露時間，然作業場所勞工暴露耳毒性物質的機率高且種類多，當噪音與耳毒性物質協同效應發生時，耳毒物質暴露可能為聽力損傷主要危險因子。因此，本研究目的評估作業場所勞工耳毒物質（有機溶劑如：苯、甲苯、乙苯、二甲苯）及噪音暴露與聽力損失之相關性。以橫斷式研究調查國內3間工廠共計102位作業勞工，包括問卷收集、個人空氣採樣、噪音暴露量評估及聽力檢查，勞工分為對照組、噪音暴露組、耳毒暴露組、噪音及耳毒同時暴露組。勞工佩戴空氣採樣幫浦6-8小時，空氣樣本使用二硫化碳進行脫附並以氣相層析儀搭配火焰離子化偵測器分析苯、甲苯、乙苯、二甲苯濃度；並同時佩戴噪音劑量計評估勞工噪音暴露狀況。最後完成聽力檢查，包括中耳鼓室儀檢查、耳聲傳射檢查、純音聽力檢查。統計分析以皮爾森積差相關分析個人空氣耳毒物質濃度、噪音暴露量與聽力損失之相關，並使用羅吉斯迴歸（Logistic Regression）分析找出導致聽力異常之危險因子。聽力異常人數比例為39.2％。對照組、噪音暴露組、耳毒暴露組、噪音及耳毒同時暴露組聽力異常比例分別為26.5％、41.9％、45.2％、66.7％，聽損勞工噪音劑量顯著較高（21.5％vs. 6.9％, p value<0.05），甲苯（r=-0.28, p value<0.05）則會顯著降低內耳外毛細胞高頻活性，羅吉斯迴歸發現「年紀越長」會增加聽力異常風險，且行為表現上出現常常需要請別人再講一次，聽力異常的可能性越高。耳毒性物質與噪音暴露皆會增加勞工聽力異常風險，耳毒物質暴露會降低內耳外毛細胞高頻活性。

Occupational hearing loss (OHL) is a major disease diagnosed in Taiwan, primarily attributed to workplace noise, ototoxic substance exposure, vibrations, and acoustic shock. Despite regulatory limits on noise levels and exposure durations has been executed, workers remain at high risk of exposure to diverse ototoxic substances. When noise and ototoxic substances act synergistically, chemical exposure may be the predominant factor in hearing impairment. This study evaluates the association between occupational exposure to ototoxic solvents (benzene, toluene, ethylbenzene, xylene), noise, and hearing loss. A cross-sectional study was conducted in three factories, assessing 102 workers through questionnaires, personal air sampling, noise dosimetry, and audiometric testing. Participants were categorized into control, noise exposure, ototoxic exposure, and combined exposure groups. Air samples were collected via personal sampling pumps, analyzed using gas chromatography withflame ionization detection, while noise exposure was quantified simultaneously with dosimeters. Hearing assessments included tympanometry, otoacoustic emissions, and pure-tone audiometry. Pearson correlation and logistic regression were used to analyze associations between exposure levels and hearing impairment. The prevalence of hearing abnormalities was 39.2%, with rates of 26.5% in the control group, 41.9% in the noise exposure group, 45.2% in the ototoxic exposure group, and 66.7% in the combined exposure group. Hearing-impaired workers had significantly higher noise doses (21.5% vs. 6.9%, p < 0.05), while toluene (r = -0.28, p < 0.05) was associated with reduced high-frequency outer hair cell activity. Logistic regression identified increasing age is associated with a higher risk of hearing impairment, and individuals who frequently ask others to repeat themselves are more likely to exhibit abnormal hearing. Exposure to both ototoxic substances and noise increases the risk of hearing impairment among workers. Specifically, exposure to ototoxic agents reduces the high-frequency activity of outer hair cells in the inner ear.