International Research Fellowship Program: Experimental Investigation into Dissolution Characteristics and Reactivity of Mineral Fibers with Implications for Toxicity

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。国际研究奖学金计划使美国科学家和工程师能够在国外进行9至24个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持塔玛拉·R·迪德里希博士与法国图卢兹大学的雅克·肖特博士合作的为期24个月的研究奖学金。迫切需要量化与地球材料中的毒性相关的参数。可呼吸矿物纤维沉积在人体肺部后，其溶解特性可通过以下方面决定其命运：在肺液中的生物耐受性；可用于反应的表面积；由颗粒尺寸控制的移位和其他清除机制；以及金属的可利用性。这项研究项目测试了这样一种假设，即：单独粉碎的锰铁矿(一种可以形成纤维的非石棉矿物)、显示生长面的矿物矿物晶体和/或在石英存在下的矿物矿物的溶解特征与已知会导致石棉相关疾病的矿物纤维的溶解特征一致(例如，纤维状砂榴石)。它包括使用混合流动反应器在模拟肺液中对多个显示生长或解理表面的明尼苏铁矿样进行溶解实验。样品在部分溶解之前和之后进行了充分的表征。对流体化学进行监测，以得出稳定的溶解速率。动力学参数和热力学数据被用在地化模型中，以模拟在各种情况下的溶解。这项研究的结果是：显示解理表面的粉碎的矿物晶体的溶解速度作为pH和表面积的函数；显示生长表面的人工合成的矿物晶体的溶解速度作为pH和表面积的函数；上述晶体单独和在石英存在的情况下在细胞外肺液和细胞内肺液中的溶解模型；明尼苏太石的溶解与纤维状砂砾石的比较；以及对上述所有情况下的溶解机制的观察。最终，这些结果将有助于建立一个更好的模型来研究矿物质纤维在肺液中的溶解，更广泛地说，矿物质粉尘在肺液中的溶解，从而更好地理解矿物毒性的决定因素之一。

0911395DiedrichThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Tamara R. Diedrich to work with Dr. Jacques Schott at the University of Toulouse in France.There is a critical need to quantify parameters related to toxicity in earth materials. Dissolution characteristics can determine the fate of respirable mineral fibers after they are deposited in the human lung by influencing: biodurability in lung fluid; surface area available for reaction; translocation and other clearance mechanisms controlled by particle dimension; and metal availability. This research project tests the hypothesis that the dissolution characteristics of either: crushed minnesotaite (a non-asbestos mineral that can form fibers) alone; minnesotaite crystals displaying growth faces; and/or minnesotaite in the presence of quartz are consistent with those of a mineral fiber that is known to cause asbestos-related disease (for example, fibrous grunerite). It consists of dissolution experiments in simulated lung fluid using a mixed flow reactor on multiple samples of minnesotaite displaying either growth or cleavage surfaces. Samples are fully characterized prior to and following partial dissolution. Fluid chemistry is monitored to derive steady-state dissolution rates. Kinetic parameters with thermodynamic data are used in geochemical models to model dissolution under a variety of scenarios.This research is resulting in: dissolution rates as a function of pH and surface area for crushed minnesotaite crystals displaying cleavage surfaces; dissolution rates as a function of pH and surface area for synthetic minnesotaite crystals displaying growth surfaces; models of dissolution in extracellular lung fluid and intracellular lung fluid for both of the above crystals alone and in the presence of quartz; comparison of minnesotaite dissolution with fibrous grunerite; and observations on dissolution mechanisms for all above scenarios. Ultimately, these results will build toward a better model for dissolution of mineral fibers, and more broadly, mineral dust, in lung fluid, and, therefore, a better understanding of one of the determinants of mineral toxicity.