Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan, ROC.
Sci Total Environ. 2009 Dec 15;408(1):43-9. doi: 10.1016/j.scitotenv.2009.09.016. Epub 2009 Oct 9.
As the use of leaded gasoline has ceased in the last decade, background lead exposure has generally been reduced. The aim of this study was to examine the effect of low-level lead exposure on human hearing loss. This study was conducted in a steel plant and 412 workers were recruited from all over the plant. Personal information such as demographics and work history was obtained through a questionnaire. All subjects took part in an audiometric examination of hearing thresholds, for both ears, with air-conducted pure tones at frequencies of 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz. Subjects' blood samples were collected and analyzed for levels of manganese, copper, zinc, arsenic, cadmium and lead with inductive couple plasma-mass spectrometry. Meanwhile, noise levels in different working zones were determined using a sound level meter with A-weighting network. Only subjects with hearing loss difference of no more than 15 dB between both ears and had no congenital abnormalities were included in further data analysis. Lead was the only metal in blood found significantly correlated with hearing loss for most tested sound frequencies (p<0.05 to p<0.0001). After adjustment for age and noise level, the logistic regression model analysis indicated that elevated blood lead over 7 microg/dL was significantly associated with hearing loss at the sound frequencies of 3000 through 8000 Hz with odds ratios raging from 3.06 to 6.26 (p<0.05-p<0.005). We concluded that elevated blood lead at level below 10 microg/dL might enhance the noise-induced hearing loss. Future research needs to further explore the detailed mechanism.
随着过去十年含铅汽油的使用停止，背景铅暴露水平普遍降低。本研究旨在探讨低水平铅暴露对人类听力损失的影响。本研究在一家钢铁厂进行，从全厂招募了 412 名工人。通过问卷获得个人信息，如人口统计学和工作经历。所有受试者都参加了听力阈值的听力测试，使用空气传导纯音，频率为 500、1000、2000、3000、4000、6000 和 8000Hz。采集受试者的血液样本，并用电感耦合等离子体质谱法分析锰、铜、锌、砷、镉和铅的水平。同时，使用带 A 加权网络的声级计测定不同工作区的噪声水平。只有双耳听力损失差值不超过 15dB 且无先天性异常的受试者才被纳入进一步的数据分析。只有血液中的铅与大多数测试频率的听力损失显著相关（p<0.05 至 p<0.0001）。在校正年龄和噪声水平后，逻辑回归模型分析表明，血铅水平超过 7μg/dL 与 3000 至 8000Hz 之间的听力损失显著相关，比值比从 3.06 到 6.26（p<0.05-p<0.005）。我们得出结论，低于 10μg/dL 的血铅水平升高可能会增强噪声引起的听力损失。未来的研究需要进一步探索详细的机制。
