Estimates of historical exposures by phase contrast and transmission electron microscopy in North Carolina USA asbestos textile plants
Estimates of historical exposures by phase contrast and transmission electron microscopy in North Carolina USA asbestos textile plants
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DOI：
10.1136/oem.2008.040410
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发表时间：
2009-09-01
影响因子：
4.9
通讯作者：
Wolf, S.
中科院分区：
文献类型：
--
作者：
Dement, J. M.;Myers, D.;Wolf, S.
目的：为了开发一个工作接触矩阵（JEM）的纤维暴露在三个石棉纺织plants和开发估计的纤维尺寸特定的exposs.Methods：历史灰尘样本从三个北卡罗来纳州，美国石棉纺织厂获得。植物特定的样品被用来表示撞击尘浓度纤维浓度相收缩显微镜（PCM）。混合模型被用来估计PCM暴露的工厂，部门，工作和日历时间。存档的膜过滤器样品进行了分析，通过透射电子显微镜（TEM），以确定双变量的直径/长度分布的空气中的纤维由工厂和operation.Results：PCM纤维水平估计从模型是非常高的，在20世纪30年代，与一些操作有超过200纤维/毫升，并随着时间的推移略有下降。对77个气载粉尘样品的TEM结果发现，只有一小部分气载纤维（直径>0.25 μ m，长度>5 μ m）被PCM测量到，并且该比例因工厂和操作而变化很大（范围为2.9%至10.0%）。空气中纤维的双变量直径/长度分布表现出相对较高的变异程度，由工厂和操作。PCM调整因素也有很大的不同，在工厂和operations.Conclusions：这些数据提供了新的信息，在三个历史上重要的石棉纺织厂的空气中的纤维水平和特性。PCM浓度高，在早年和TEM数据表明，绝大多数空气中的纤维吸入的工人是短于5微米的长度，因此不包括在PCM为基础的纤维计数。
Objectives: To develop a job-exposure matrix (JEM) for fibre exposures in three asbestos textile plants and to develop estimates of fibre size-specific exposures.Methods: Historical dust samples from three North Carolina, USA asbestos textile plants were obtained. Plant specific samples were used to express impinger dust concentrations as fibre concentrations by phase contract microscopy (PCM). Mixed models were used to estimate PCM exposures by plant, department, job and calendar time. Archived membrane filter samples were analysed by transmission electron microscopy (TEM) to determine the bivariate diameter/length distribution of airborne fibres by plant and operation.Results: PCM fibre levels estimated from the models were very high in the 1930s, with some operations having in excess of 200 fibres/ml, and decreased appreciably over time. TEM results for 77 airborne dust samples found that only a small proportion of airborne fibres were measured by PCM (>0.25 mu m in diameter and >5 mu m in length) and the proportion varied considerably by plant and operation (range 2.9% to 10.0%). The bivariate diameter/length distribution of airborne fibres demonstrated a relatively high degree of variability by plant and operation. PCM adjustment factors also varied substantially across plants and operations.Conclusions: These data provide new information concerning airborne fibre levels and characteristics in three historically important asbestos textile plants. PCM concentrations were high in the early years and TEM data demonstrate that the vast majority of airborne fibres inhaled by the workers were shorter than 5 mu m in length, and thus not included in the PCM-based fibre counts.