Christiani D C, Ye T T, Zhang S, Wegman D H, Eisen E A, Ryan L A, Olenchock S A, Pothier L, Dai H L
Department of Environmental Health (Occupational Health Program), Harvard School of Public Health and Pulmonary/Critical Care Unit, Massachusetts General Hospital, Boston, USA.
Am J Ind Med. 1999 Apr;35(4):321-31. doi: 10.1002/(sici)1097-0274(199904)35:4<321::aid-ajim1>3.0.co;2-l.
To evaluate the relationship between long-term exposure to cotton dust and Gram-negative bacterial endotoxin on lung function, we conducted an 11-year follow-up study of cotton textile workers in Shanghai, China.
Workers at a nearby silk-thread manufacturing mill were used as a referent population. Ninety percent of the original cohort of 445 cotton and 467 silk textile workers--both active and retired--were identified for testing in the 11th year. Questionnaires and spirometric testing were performed, as well as cotton dust and endotoxin sampling at three points over the 11-year follow-up period: at baseline, at Year 5, and at Year 11. After excluding deaths and subjects on sick-leave, 84% of the original cohort had complete health and environmental data.
The data were reanalyzed using generalized estimating equations feedback model which allow for subject transfer over time between work areas, various exposure levels to dust and endotoxin, and FEV1. Cotton workers had a larger loss of FEV1 during the first 5 years of study (-40 mls/yr) as compared with the second 6 years of follow-up (-18 mls/yr). During the same periods, the average decline among silk workers was slightly higher in the first period, but was more consistent (-30 mls/yr vs. -27 mls/yr), and these differences could not be explained by worker selection or dropout. When cumulative exposure to dust and endotoxin were estimated and used in a multivariate model (GEE) for FEV1 loss, cumulative dust, but not endotoxin, was associated with 11-year loss in FEV1 after adjustments for confounders. There was evidence of feedback between dust-exposure levels and FEV1, indicating the existence of a healthy-worker survivor effect. After accounting for a healthy-worker survivor effect, we found a significant relationship between dust exposure and FEV1 decline.
Our results suggest that cotton dust is more strongly associated with chronic airflow limitation than associated endotoxins. Further work is needed to clarify potential reversibility after cessation of exposure, and the relative contributions of dust, endotoxin, and tobacco to chronic respiratory impairment in cotton and other vegetable-exposed workers.
为评估长期接触棉尘和革兰氏阴性菌内毒素与肺功能之间的关系，我们对中国上海的棉纺织工人进行了一项为期11年的随访研究。
将附近丝线制造厂的工人作为对照人群。在第11年，对原队列中445名棉纺织工人和467名丝纺织工人（包括在职和退休人员）中的90%进行了检测。进行了问卷调查和肺活量测定，以及在11年随访期内三个时间点（基线、第5年和第11年）的棉尘和内毒素采样。在排除死亡和病假人员后，84%的原队列有完整的健康和环境数据。
使用广义估计方程反馈模型对数据进行重新分析，该模型考虑了随时间在工作区域之间的人员转移、对粉尘和内毒素的不同暴露水平以及第一秒用力呼气容积（FEV1）。与随访的后6年（每年下降18毫升）相比，棉纺织工人在研究的前5年FEV1下降幅度更大（每年下降40毫升）。在同一时期，丝纺织工人在第一个时期的平均下降幅度略高，但更为一致（每年下降30毫升对每年下降27毫升），这些差异无法用工人选择或失访来解释。当估计粉尘和内毒素的累积暴露量并将其用于FEV1损失的多变量模型（广义估计方程）时，在对混杂因素进行调整后，累积粉尘而非内毒素与11年的FEV1损失相关。有证据表明粉尘暴露水平与FEV1之间存在反馈，表明存在健康工人幸存者效应。在考虑健康工人幸存者效应后，我们发现粉尘暴露与FEV1下降之间存在显著关系。
我们的结果表明，棉尘与慢性气流受限的关联比内毒素更强。需要进一步开展工作，以阐明接触停止后的潜在可逆性，以及粉尘、内毒素和烟草对棉纺织工人及其他接触植物性粉尘工人慢性呼吸损害的相对贡献。
