a Division of Environmental Health Sciences, School of Public Health, University of Minnesota , Minneapolis , Minnesota.
J Occup Environ Hyg. 2014;11(9):613-24. doi: 10.1080/15459624.2014.890287.
Different dimensions of elongate mineral particles (EMP) have been proposed as being relevant to respiratory health end-points such as mesothelioma and lung cancer. In this article, a methodology for converting personal EMP exposures measured using the National Institute for Occupational Safety and Health (NIOSH) 7400/7402 methods to exposures based on other size-based definitions has been proposed and illustrated. Area monitoring for EMP in the taconite mines in Minnesota's Mesabi Iron Range was conducted using a Micro Orifice Uniform Deposit Impactor (MOUDI) size-fractionating sampler. EMP on stages of the MOUDI were counted and sized according to each EMP definition using an indirect-transfer transmission electron microscopy (ISO Method 13794). EMP were identified using energy-dispersive x-ray and electron diffraction analysis. Conversion factors between the EMP counts based on different definitions were estimated using (1) a linear regression model across all locations and (2) a location-specific ratio of the count based on each EMP definition to the NIOSH 7400/7402 count. The highest fractions of EMP concentrations were found for EMP that were 1-3 μm in length and 0.2-0.5 μm in width. Therefore, the current standard NIOSH Method 7400, which only counts EMP >5 μm in length and ≥ 3 in aspect ratio, may underestimate amphibole EMP exposures. At the same time, there was a high degree of correlation between the exposures estimated according to the different size-based metrics. Therefore, the various dimensional definitions probably do not result in different dose-response relationships in epidemiological analyses. Given the high degree of correlation between the various metrics, a result consistent with prior research, a more reasonable metric might be the measurement of all EMP irrespective of size. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: figures detailing EMP concentration.].
不同维度的拉长型矿物颗粒 (EMP) 已被提出与呼吸健康终点相关，如间皮瘤和肺癌。在本文中，提出并说明了一种将使用美国国家职业安全与健康研究所 (NIOSH) 7400/7402 方法测量的个人 EMP 暴露量转换为基于其他尺寸定义的暴露量的方法。在明尼苏达州梅萨比铁矿区的铁矿中，使用微孔均匀沉积撞击器 (MOUDI) 尺寸分级采样器进行 EMP 的区域监测。根据每个 EMP 定义，使用间接转移透射电子显微镜 (ISO 方法 13794) 对 MOUDI 各阶段的 EMP 进行计数和尺寸测量。使用能量色散 X 射线和电子衍射分析对 EMP 进行鉴定。使用 (1) 所有地点的线性回归模型和 (2) 基于每个 EMP 定义的计数与 NIOSH 7400/7402 计数的特定地点比值，估计了基于不同定义的 EMP 计数之间的转换因子。EMP 浓度的最高分数发现于长度为 1-3μm 且宽度为 0.2-0.5μm 的 EMP。因此，当前仅计数长度>5μm 且纵横比≥3 的 EMP 的现行 NIOSH 标准方法 7400 可能低估了角闪石 EMP 暴露量。同时，根据不同基于尺寸的指标估计的暴露量之间存在高度相关性。因此，在流行病学分析中，各种维度的定义可能不会导致不同的剂量-反应关系。鉴于各种指标之间存在高度相关性，这与先前的研究一致，更合理的指标可能是测量所有 EMP，而不论其尺寸大小。[本文提供了补充材料。请访问期刊《职业与环境卫生杂志》的出版商在线版本，以获取以下免费补充资源：详细说明 EMP 浓度的图。]。
