AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Inactivation of Aerosolized Bacillus Anthracis Surrogates by Combustion Products of Energetic Powdered Materials: Effect of Exposure Time
WORRAWIT NAKPAN, Michael Yermakov, Reshmi Indugula, Tiina Reponen, Song Wang, Mirko Schoenitz, Edward Dreizin, Sergey A. Grinshpun, University of Cincinnati
Abstract Number: 100 Working Group: Bioaerosols
Abstract The bio-weapon stockpiles and facilities can be targeted militarily in a terrorist attack. In case of an explosion or fire outbreak, highly pathogenic microorganisms may become airborne and subjected to atmospheric transport, which represents a high-level health risk for millions. There is evidence that some bio-threat agents such as Bacillus anthracis bacterial spores are extremely stress-resistant and may survive harsh conditions. As novel biocidal materials are being developed to neutralize the threat, it is important to better understand and quantify the response of viable airborne spores to environmental conditions, including thermal and chemical stresses. In this study, combustion products of different materials (Al, Al•I2, Al•B•I2, Mg, Mg•S, and Mg•B•I2) were examined with respect to their ability to inactivate aerosolized spores of Bacillus thuringiensis var kurstaki (Btk), a well-recognized surrogate of B. anthracis. An inactivation factor (IF) was determined as a function of the spore exposure time, approximately from 0.1 to 2 seconds. The IF-value was quantified by comparing culture-based counts from the combustion-exposed and non-exposed samples. The tests were conducted at two air temperatures: weighted average ≈170°C (below the iodine boiling point) and ≈260°C (above it). The inactivation effect generally increased exponentially with exposure time. Under low temperature condition, the chemical effect of iodine was negligibly small while it became significant when the temperature was high enough for iodine to remain in the gaseous phase and continue inactivating the aerosolized spores over the entire exposure period. Combustion products of several new composite materials were found to effectively inactivate the aerosolized spores suggesting, in addition to the iodine effect, a significant chemical inactivation from boron and oxidation of magnesium. The results demonstrate a complex kinetics of the spore inactivation process. This investigation will contribute to major bio-agent defeat programs.