職業鉛與噪音暴露對於聽覺能力影響──橫斷式研究

Lead Exposure and Effects on Hearing in a Battery Manufacturing Plant － Cross-Sectional Study

近年來針對環境中重金屬暴露對於人類或者動物潛在危害的研究報告頗多，也描述了環境重金屬對人體各別系統的傷害。然而在聽覺毒性方面之研究並不多見，根據以往有限的流行病學調查與動物實驗指出，鉛（lead；Pb）、汞 (mercury；Hg)、砷 (arsenic；As) 與錫化合物（tin；Sn）等都會影響聽覺功能，而其中鉛在台灣是最被廣泛使用重金屬之一。本研究的研究族群是收集某鉛蓄電池工廠 89 男性員工人視為暴露組，另一組則是收集 51 位到高雄醫學大學附設中和紀念醫院做體檢的人，其中排除掉 7 個有中耳疾病、2 鼓膜受傷者及 5 個問卷或體檢資料不齊全者，因此有效樣本數為 126 人，分為暴露組 71 人、非暴露組 51 人，全部為男性勞工。非暴露組的工作性質多為一般文書處理員、貿易公司的主管、業務員或公務員等，因此不會有職業鉛與噪音暴露的疑慮，且環境中噪音在 80 分貝以下。研究結果顯示，非暴露組各頻率與取對數後的血鉛值無統計上顯著意義。暴露組則是在 2k、4k 與 6k 有統計上顯著意義（p<0.05），且為正相關（r ＝ 0.26~0.40）。利用線性複迴歸分析探討血中鉛與噪音對聽覺能力的影響，結果顯示，在 4k 與 6k 頻率的模型裡，取對數後的血鉛值在控制噪音暴露量與其他干擾因子後，每增加 1 個單位的 Log PbB 4k 與 6k 頻率的聽力閾值會分別增加 12 與 13 分貝，年齡在控制其他干擾因子後每增加 1 歲，4k 與 k6 頻率的聽力閾值會增加約 1 分貝。0.5k、1k 與 2k 頻率的模型裡，控制其他干擾因子後僅年齡有顯著意義。

Few epidemiologic studies have been carried out of heavy metals, which have been suggested to be ototoxins in humans, in the environment. Based on these epidemiologic studies, heavy metals such as lead, arsenic and manganese may cause hearing loss in humans and animals. No other metal presents a broader range of problems, from the multiplicity of potential routes of exposure to the spectrum of affected organs and systems, than lead. This cross-sectional study was conducted to examine the relationship among blood lead, noise exposure and auditory ability at a lead battery manufacturing factory. The workers were divided into a lead combined noise-exposed group of 75 workers, and a reference group of 51 persons who were not occupationally exposed to lead and noise. All of the subjects underwent evaluations including self-reported questionnaires, personal histories, clinical examinations, and laboratory tests to determine the blood lead level and pure tone hearing threshold in a soundproof booth. The level of noise in the lead battery manufacturing factory was measured by sound level meters. Among the exposed workers, a significant association was found between hearing thresholds and log PbB. The hearing threshold rose as the log PbB increased, especially at 2000, 4000 and 6000 Hz. Multiple linear regression was applied to determine the effects of lead and noise relative to auditory ability. In the 4000 and 6000 Hz model of linear regression, age and log transformed blood lead levels (log PbB) were associated significantly with auditory ability along with adjustment of noise levels. When considering the effects of age, noise level, smoking, and alcohol consumption, the log transformed blood