METHODS FOR ASSESSING SYNTHETIC TEXTILE DUST EXPOSURE

直到最近，合成纤维(ST)粉尘还被认为很少或根本不会对呼吸系统产生不良影响。这在一定程度上是因为粉尘的成分被认为是无害的，而且这些纤维被认为太大，不能沉积在接触尘埃的工人的下呼吸系统中。出于这些原因，ST粉尘被归类为未受其他方面管制的颗粒物(PNOR)。最近的研究发现，ST粉尘的暴露水平远低于PNOR允许暴露限值(PEL)，与急性和慢性呼吸影响有关。现在也有证据表明，部分ST粉尘可以沉积在肺的所有区域。为了今后对ST粉尘的呼吸影响进行研究，需要改进评估暴露的方法，因为标准的PNOR方法不评估ST粉尘的组成或可能沉积在肺部特定区域的ST颗粒大小。拟议研究的第一部分将调查ST粉尘采样和分析的几种替代方法，并将它们与标准的PNOR方法进行比较。在一家大型ST轧钢厂的精炼部，已经使用标准和替代的空气监测方法采集了54组匹配的空气样本(258个空气过滤器)，并采用了并排抽样方案。使用这些空气样本，将计算出三种不同的定量暴露指标：质量浓度、颗粒数浓度和纤维数浓度。还将确定沉积在肺部三个区域的ST粉尘的组成。将根据在空气监测期间记录的对粉尘的感知制定定性的ST粉尘暴露措施。对于每一种定量和定性暴露措施，将对标准方法和替代方法进行比较。这些结果将被用来建议改进的采样和分析方法，以便在未来调查呼吸道疾病的职业流行病学研究中进行ST粉尘暴露评估。拟议研究的第二部分将调查同一家当地纺织厂的ST粉尘暴露情况。将进行统计建模，以确定ST粉尘暴露措施的生产过程决定因素。这些结果将被用来帮助工厂针对ST精加工工艺的特定方面进行ST粉尘控制。

Until recently, synthetic textile (ST) dust was thought to produce little or no adverse respiratory effects. This is in part because the composition of the dust was considered harmless and because the fibers were thought to be too large to deposit in the lower respiratory systems of exposed workers. For these reasons, ST dust is regulated under the classification, Particulate Not Otherwise Regulated (PNOR). Recent studies have found acute and chronic respiratory effects associated with ST dust at exposure levels well under the PNOR Permissible Exposure Limit (PEL). There is now also evidence that some fraction of ST dust can be deposited in all regions of the lung. To conduct future studies of the respiratory effects of ST dust, improved methods for assessing exposure are needed because the standard PNOR method does not assess the ST dust composition or the ST particle size fractions likely to deposit in specific regions of the lung. Part one of the proposed study will investigate several alternative methods for ST dust sampling and analysis and compare them to the standard PNOR method. Fifty-four matched sets (258 air filters) of air samples have already been collected using standard and alternative air monitoring methods in a side-by-side sampling scheme in a finishing department at a large ST mill. Using these air samples, three different quantitative exposure measures will be calculated: mass concentration, particle number concentration, and fiber number concentration. The composition of the ST dust that deposits in the three regions of the lung will also be determined. Qualitative ST dust exposure measures will be developed based on perceptions of dustiness recorded during the air monitoring. For each quantitative and qualitative exposure measure, the standard and alternative methods will be compared. The results will be used to recommend improved sampling and analytical methods for conducting an exposure assessment for ST dust in future occupational epidemiologic studies investigating respiratory disease. Part two of the proposed study will investigate ST dust exposure in the same local textile mill. Statistical modeling will be preformed to identify the production process determinants of the ST dust exposure measures. These results will be used to assist the mill in targeting specific aspects of the ST finishing process for ST dust control.