Hearing loss and DNA damage among noise-exposed workers at paper recycling mill

• Main Authors: Lin,Li-Mei, 林麗梅
• Other Authors: 郭憲文
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/80253646969770166451

碩士 === 中國醫藥大學 === 環境醫學研究所 === 92 === Long-term exposure to noise can induced permanent hearing loss and DNA damage in workers, but this link has not been clearly established with workers at the paper recycling mill. The objective of this study was to evaluate hearing threshold shifts and DNA damage using Pure-tone audiometry and comet assay in paper recycling workers who had been chronically exposed to noise in the workplace. The effect of occupational noise exposure on hearing threshold shifts is studied in workers of paper recycling mill. Study subjects included 291 males and 19 females accepted Pure-tone audiometry is performed personal history and Occupational Stress Indicator（OSI）questionnaires are adopted for the cross-sectional study. Blood samples were taken from 88 subjects and lymphocytes were isolated for analysis of DNA damage by single-cell gel electrophoresis (comet) technique. The noise-exposure group was regularly exposed to noise levels over 85dB, and work duration was over ten years. The average of hearing threshold shifts at high frequencies(4k, 6k, 8kHz) is considerably larger than that at low frequencies(0.5k, 1k, 2k Hz). The moderate to severe degree of hearing loss of the paper mill workplace of subjects showed maximum notches at the frequency of 4 kHz. The noise-exposure group grades of DNA damage were significantly higher then the controls. .Based on smoking status, grades of DNA damage were significantly higher in the noise-exposed group compared to the controls. Multiple regression model analysis revealed that noise-exposure and wearing personal protective equipment had a significant effect on grades of DNA damage, adjusting for other factors, but smoking habit had no significant effect. In conclusion, workers chronically exposed to noise had significantly greater DNA damage and Permanent Threshold Shift （PTS）, but the mechanisms involved are unclear. Also, some individual workers appeared to be much more susceptible to DNA damage than others. Comet assay was useful in evaluating the genotoxic effect of noise exposure.