Design of a Coupled Flame and Cell Exposure System for Study of Combustion Particle Toxicity

SHUBHAM SUNIL SHARMA, Dhruv Mitroo, Shu-Wen You, Joseph V. Puthussery, Rajan K. Chakrabarty, Benjamin Kumfer, Washington University in St. Louis

     Abstract Number: 502
     Working Group: Aerosol Exposure

Abstract
Exposure to particulate matter has been attributed to various health risks, notably asthma, lung cancer, and heart disease. Carbonaceous particles, or soot, emitted from combustion sources have been identified to induce cytotoxicity in various mammalian cells. Both natural events such as wildfires and anthropogenic activities such as driving, cooking, and open waste incineration are significant sources of soot. Soot, depending on its source, can have highly variable physicochemical properties that are relevant to cell health, such as particle size, morphology, surface area, surface reactivity, and composition of associated hydrocarbons including PAHs. Here a single bench top experimental combustion system is presented that selectively produces soot with a wide array of physical and chemical properties to mimic particles generated from specific sources. The system can produce premixed flames and non-premixed flames with normal and inverted configurations. Characterization by electron microscopy, XPS, SMPS, and EC/OC is performed to demonstrate the wide variation that can be achieved with this system. Results from this group indicate that cell viability is significantly sensitive to the flame type and parameters such as flame temperature and equivalence ratio. Traditional cell exposure by addition of a suspension of soot in cell media is challenging due to colloidal instability and difficulty in preserving the original size distribution. To better simulate the mechanism of real-life exposure, an exposure system is being developed that directly  exposes cells growing in a standard multi-well culture plate to the flame-generated soot aerosol with controlled deposition to the air/liquid interface. The combined system provides a unique platform for assessing relative toxicity from various sources, and for elucidating the particle properties that are most relevant to health outcomes.