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

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。国际研究奖学金项目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。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Tamara R. Diedrich博士与法国图卢兹大学的Jacques Schott博士一起进行为期24个月的研究。迫切需要量化与土材料毒性有关的参数。溶解特性可以通过影响肺液中的生物耐久性来决定可呼吸性矿物纤维沉积在人体肺部后的命运；可用于反应的表面积；颗粒尺寸控制的易位等清除机制；金属的可用性。本研究项目测试了以下两种溶解特性的假设：单独破碎的明尼苏达矿（一种可以形成纤维的非石棉矿物）；显示生长面的明尼苏达晶体；和/或含有石英的辉绿石与已知会引起石棉相关疾病的矿物纤维（例如纤维绿辉石）一致。它包括在模拟肺液中溶解实验，使用混合流反应器对显示生长或解理表面的多个明尼苏达铁矿样品进行溶解实验。样品在部分溶解之前和之后被充分表征。监测流体化学以得出稳态溶解速率。在地球化学模型中使用热力学数据的动力学参数来模拟各种情况下的溶解。这项研究的结果是：溶解速率作为pH值和表面积的函数，破碎的明尼苏达铁矿晶体显示解理面；溶出速率与pH值和显示生长表面的合成钙钛矿晶体表面积的关系；上述两种晶体单独和石英存在时在细胞外肺液和细胞内肺液中的溶解模型；镁辉石与纤维绿辉石溶蚀作用的比较并对上述所有情景的溶解机理进行了观察。最终，这些结果将建立一个更好的矿物纤维溶解模型，更广泛地说，矿物粉尘在肺液中的溶解，因此，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.