The administration of talc particles to the pleural space for the treatment of pleural effusions has been practiced for nearly seventy years with little understanding of the key particle parameters that lead to desired or undesired clinical outcomes. Fatal side effects, such as acute respiratory distress syndrome (ARDS), have recently been correlated to specific talc sources. In the past, this problem has been approached almost unambiguously from a purely clinical standpoint with very little particle property and material analysis. The physical properties (primary particle structure, wettability, surface charge, etc) and chemical state (impurity levels and type) of talc may vary from source to source. Additionally, the particle size distributions and primary particle features (e.g. shape, exposed surfaces, and remnant impurities) may largely fluctuate with processing parameters, which also vary by manufacturer and grade. The potential influence of these factors on the frequency of ARDS in clinical outcomes is being evaluated in this study to aid the development of engineered particulate systems for the treatment of pleural effusions.