Naturally Occurring Asbestos: Potential for Human Exposure, Southern Nevada, USA
Naturally Occurring Asbestos: Potential for Human Exposure, Southern Nevada, USA
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DOI：
10.2136/sssaj2013.05.0183
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发表时间：
2013-11-01
影响因子：
2.9
通讯作者：
Freudenberger, Frederick
中科院分区：
文献类型：
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作者：
Buck, Brenda J.;Goossens, Dirk;Freudenberger, Frederick
角闪石石棉矿物是已知的人类致癌物，并且已经制定了许多法规来限制职业暴露。这些矿物质也可能存在于自然环境中，在那里它们可能更难以控制。我们应用了一套不同的分析方法，包括扫描电子显微镜/能量色散光谱，电子探针分析，X射线衍射，场发射扫描电子显微镜岩石，土壤和灰尘样品和附着在衣服样品和汽车的颗粒。我们在岩石、土壤和灰尘中发现了天然存在的纤维阳起石，这是一种受管制的闪石石棉矿物，可以通过风、水、汽车或户外娱乐活动后的衣服运输。这些纤维状角闪石的来源是内华达州南部和亚利桑那州的几个深成岩和含石棉基岩的冲积扇。角闪石纤维的形态与美国环保署超级基金在蒙大拿州利比的研究点发现的角闪石纤维相似。我们发现，在研究区的纤维颗粒的形态没有实质性的变化时，原始基岩风化成土壤，颗粒被侵蚀和运输通过风和/或水，并最终解决和积累在自然或其他表面。由于博尔德市、亨德森和拉斯维加斯的大量人口位于距离污染源仅几公里，有时甚至只有几十米的下风处，而且由于大多数颗粒物在排放后以悬浮状态被输送，博尔德市、亨德森和拉斯维加斯的潜在大量人口可能会暴露。这项研究表明，对几个人口众多的地区存在潜在的公共卫生风险。
Amphibole asbestos minerals are known human carcinogens, and many regulations have been developed to limit occupational exposure. These minerals can also occur in the natural environment, where they may be more difficult to control. We applied a diverse set of analytical methods including scanning electron microscopy/energy dispersive spectroscopy, electron probe analysis, x-ray diffraction, and field-emission scanning electron microscopy to rock, soil, and dust samples and to particles attached to clothing samples and cars. We found naturally occurring fibrous actinolite, a regulated amphibole asbestos mineral, in rock, soil, and dust that can be transported by wind, water, cars, or on clothing after outdoor recreational activities. Sources of these fibrous amphiboles are several plutons in southern Nevada and Arizona and alluvial fans emanating from asbestos-containing bedrock. The morphology of the amphibole fibers is similar to amphibole fibers found in the USEPA Superfund site at Libby, MT. We found that the morphometry of the fibrous particles in the study area did not substantially change when the original bedrock weathered into soil, and particles were eroded and transported through wind and/or water and finally settled and accumulated on natural or other surfaces. Because large populations in Boulder City, Henderson, and Las Vegas are located only a few kilometers, sometimes even only a few tens of meters, downwind from the sources, and because most of the particles are transported in suspension after they are emitted, potentially large populations in Boulder City, Henderson, and perhaps Las Vegas could be exposed. This study demonstrates a potential public health risk to several large population areas.