Stayner L, Kuempel E, Gilbert S, Hein M, Dement J
Division of Epidemiology and Biostatistics MC923, University of Illinois at Chicago, School of Public Health, 1603 W Taylor Street, Chicago, IL 60612-4394, USA.
Occup Environ Med. 2008 Sep;65(9):613-9. doi: 10.1136/oem.2007.035584. Epub 2007 Dec 20.
Evidence from toxicological studies indicates that the risk of respiratory diseases varies with asbestos fibre length and width. However, there is a total lack of epidemiological evidence concerning this question.
Data were obtained from a cohort mortality study of 3072 workers from an asbestos textile plant which was recently updated for vital status through 2001. A previously developed job exposure matrix based on phase contrast microscopy (PCM) was modified to provide fibre size-specific exposure estimates using data from a re-analysis of samples by transmission electron microscopy (TEM). Cox proportional hazards models were fit using alternative exposure metrics for single and multiple combinations of fibre length and diameter.
TEM-based cumulative exposure estimates were found to provide stronger predictions of asbestosis and lung cancer mortality than PCM-based estimates. Cumulative exposures based on individual fibre size-specific categories were all found to be highly statistically significant predictors of lung cancer and asbestosis. Both lung cancer and asbestosis were most strongly associated with exposure to thin fibres (<0.25 microm). Longer (>10 microm) fibres were found to be the strongest predictors of lung cancer, but an inconsistent pattern with fibre length was observed for asbestosis. Cumulative exposures were highly correlated across all fibre size categories in this cohort (0.28-0.99, p values <0.001), which complicates the interpretation of the study findings.
Asbestos fibre dimension appears to be an important determinant of respiratory disease risk. Current PCM-based methods may underestimate asbestos exposures to the thinnest fibres, which were the strongest predictor of lung cancer or asbestosis mortality in this study. Additional studies are needed of other asbestos cohorts to further elucidate the role of fibre dimension and type.
毒理学研究证据表明，呼吸系统疾病的风险随石棉纤维的长度和宽度而变化。然而，关于这个问题完全缺乏流行病学证据。
数据来自对一家石棉纺织厂3072名工人的队列死亡率研究，该研究最近更新至2001年的生命状况。基于相差显微镜（PCM）先前开发的工作暴露矩阵进行了修改，以使用透射电子显微镜（TEM）对样品重新分析的数据提供纤维尺寸特异性暴露估计。使用纤维长度和直径的单一及多种组合的替代暴露指标拟合Cox比例风险模型。
发现基于TEM的累积暴露估计比基于PCM的估计能更有力地预测石棉肺和肺癌死亡率。基于个体纤维尺寸特异性类别的累积暴露均被发现是肺癌和石棉肺的高度统计学显著预测因子。肺癌和石棉肺均与细纤维（<0.25微米）暴露最密切相关。发现较长（>10微米）纤维是肺癌的最强预测因子，但石棉肺的纤维长度模式不一致。该队列中所有纤维尺寸类别之间的累积暴露高度相关（0.28 - 0.99，p值<0.001），这使研究结果的解释复杂化。
石棉纤维尺寸似乎是呼吸系统疾病风险的重要决定因素。当前基于PCM的方法可能低估了对最细纤维的石棉暴露，而最细纤维是本研究中肺癌或石棉肺死亡率的最强预测因子。需要对其他石棉队列进行更多研究，以进一步阐明纤维尺寸和类型的作用。
