Rohs Amy M, Lockey James E, Dunning Kari K, Shukla Rakesh, Fan Huihao, Hilbert Tim, Borton Eric, Wiot Jerome, Meyer Cristopher, Shipley Ralph T, Lemasters Grace K, Kapil Vikas
Department of Environmental Health, University of Cincinnati College of Medicine, 3223 Eden Avenue, ML 0056, Cincinnati, OH 45267, USA.
Am J Respir Crit Care Med. 2008 Mar 15;177(6):630-7. doi: 10.1164/rccm.200706-841OC. Epub 2007 Dec 6.
From 1921 to 1990, vermiculite ore from Libby, Montana, was shipped worldwide for commercial and residential use. A 1980 study of a manufacturing facility using Libby vermiculite was the first to demonstrate a small but significant prevalence of pleural chest radiographic changes associated with amphibole fibers contained in the ore.
This follow-up study of the original cohort evaluated the extent of radiographic changes and cumulative fiber exposure (CFE) 25 years after cessation of exposure.
From the original cohort of 513 workers, 431 (84%) were living and available for participation and exposure reconstruction. Of these, 280 (65%) completed both chest radiographs and interviews. Primary outcomes were pleural and/or interstitial changes.
Pleural and interstitial changes were demonstrated in 80 (28.7%) and 8 (2.9%) participants, respectively. Of those participants with low lifetime CFE of less than 2.21 fiber/cc-years, 42 (20%) had pleural changes. A significant (P < 0.001) exposure-response relationship of pleural changes with CFE was demonstrated, ranging from 7.1 to 54.3% from the lowest to highest exposure quartile. Removal of individuals with commercial asbestos exposure did not alter this trend.
This study indicates that exposure within an industrial process to Libby vermiculite ore is associated with pleural thickening at low lifetime CFE levels. The propensity of the Libby amphibole fibers to dramatically increase the prevalence of pleural changes 25 years after cessation of exposure at low CFE levels is a concern in view of the wide national distribution of this ore for commercial and residential use.
1921年至1990年期间，蒙大拿州利比市的蛭石矿被运往世界各地用于商业和住宅用途。1980年对一家使用利比蛭石的制造工厂进行的一项研究首次表明，与该矿石中所含角闪石纤维相关的胸膜胸部X线改变的患病率虽低但具有统计学意义。
这项对原始队列的随访研究评估了接触停止25年后X线改变的程度和累积纤维暴露量（CFE）。
在最初的513名工人队列中，有431人（84%）在世且可参与研究及暴露重建。其中，280人（65%）完成了胸部X线检查和访谈。主要结局为胸膜和/或间质改变。
分别有80名（28.7%）和8名（2.9%）参与者出现胸膜和间质改变。在那些终生CFE低于2.21纤维/立方厘米-年的参与者中，有42人（20%）出现胸膜改变。胸膜改变与CFE之间存在显著的（P < 0.001）暴露-反应关系，从最低暴露四分位数到最高暴露四分位数，范围为7.1%至54.3%。排除有商业石棉接触史的个体后，这一趋势未改变。
本研究表明，在工业生产过程中接触利比蛭石矿与低终生CFE水平下的胸膜增厚有关。鉴于这种矿石在商业和住宅用途上在全国广泛分布，利比角闪石纤维在低CFE水平下接触停止25年后显著增加胸膜改变患病率的倾向令人担忧。
