Carbon Nanotube and Nanofiber Exposure Assessments: An Analysis of 14 Site Visits.

Annals of Occupational Hygiene Pub Date : 2015-07-01 Epub Date: 2015-04-07 DOI:10.1093/annhyg/mev020
Matthew M Dahm, Mary K Schubauer-Berigan, Douglas E Evans, M Eileen Birch, Joseph E Fernback, James A Deddens
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引用次数: 80

Abstract

Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 µg m(-3) as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 µg m(-3) with a geometric mean (GM) of 0.34 µg m(-3) and an 8-h TWA of 0.16 µg m(-3). PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 µg m(-3) with a GM of 1.21 µg m(-3). PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm(3) with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2-5 µm range as well as agglomerates >5 µm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman ρ = 0.39, P < 0.0001). Overall, EC PBZ and area TWA samples were below the NIOSH REL (96% were <1 μg m(-3) at the respirable size fraction), while 30% of the inhalable PBZ EC samples were found to be >1 μg m(-3). Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF materials by monitoring EC at both the respirable and inhalable size fractions. Concurrent TEM samples should be collected to confirm the presence of CNT and CNF.

碳纳米管和纳米纤维暴露评估:14个站点访问的分析。
最近的证据表明,接触碳纳米管(CNT)和碳纳米纤维(CNF)可能造成广泛的健康影响。作为回应,国家职业安全与健康研究所(NIOSH)为碳纳米管和碳纳米管设定了建议的暴露限值(REL): 1µg(-3)作为可吸入尺寸部分的元素碳(EC)的8小时时间加权平均值(TWA)。本研究的目的是对美国碳纳米管和碳纳米管制造商和用户进行全行业的暴露评估。共访问了14个站点,以评估CNT(13个站点)和CNF(1个站点)的暴露情况。采用NIOSH 5040法采集个人呼吸区(PBZ)和区域样本,测定EC的可吸入和可呼吸质量浓度。在9个地点采集可吸入PBZ样本,在其余5个地点同时采集可吸入PBZ和可吸入PBZ样本。透射电子显微镜(TEM)的PBZ和面积样品也收集在可吸入的大小部分,并分析量化和大小碳纳米管和碳纳米管团聚体和纤维暴露。可吸入EC PBZ浓度范围为0.02 ~ 2.94µg m(-3),几何平均值(GM)为0.34µg m(-3), 8 h TWA为0.16µg m(-3)。PBZ样品在EC的可吸入粒径范围为0.01 ~ 79.57µg m(-3), GM为1.21µg m(-3)。透射电镜分析的PBZ样品显示浓度范围为0.0001至1.613 CNT或cnf结构每厘米(3),GM为0.008,8小时TWA浓度为0.003。最常见的碳纳米管结构尺寸是2-5µm范围内较大的团聚体以及>5µm的团聚体。可吸入样品中EC的质量与透射电镜结构计数之间存在统计学显著相关(Spearman ρ = 0.39, P < 0.0001)。总体而言,EC PBZ和区域TWA样品低于NIOSH REL(96%为1 μg m(-3))。在了解更多与较大团聚体相关的健康影响的信息之前,通过监测可吸入和可吸入颗粒的EC来评估工人对空气中碳纳米管和碳纳米管材料的暴露似乎是谨慎的。应同时收集TEM样品以确认碳纳米管和碳纳米管的存在。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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