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EXAMINING THE INFLAMMATORY RESPONSES OF HAPS: THE ROLE OF OZONE AND OTHER PHTOTCHEMICAL TRANSFORMATION PRODUCTS
SEXTON, K., M. DOYLE, K. DE BRUJINE, S. EBERVILLER, H. JEFFERIES, AND I. JASPERS. EXAMINING THE INFLAMMATORY RESPONSES OF HAPS: THE ROLE OF OZONE AND OTHER PHTOTCHEMICAL TRANSFORMATION PRODUCTS. Presented at Society for Pediatric and Perinatal Epidemiologic Research, San Deigo, CA, March 05 - May 09, 2006.
The chemistry and health effects of individual hazardous air pollutants (HAPS) have been studied for many years. Once released into the atmosphere, HAPS interact with hydroxyl radicals and ozone (created by photochemical processes), to produce many different products, whose toxic potential is currently unclear. In this study, three common HAPS (methanol, isoprene(ISO) and 1,3-butadiene(BD)) underwent photochemical transformations using real sunlight, generating a range of photochemical transformation products, including organic carbonyls such as formaldehyde and ozone. The objective of this study is to determine the role of ozone in the effects caused by the photochemically active HAPS mixtures. Using the UNC outdoor smog chambers interfaced with an in vitro exposure system, A549 cells were exposed to dynamic atmospheric mixtures. Exposure to the photochemically generated products of BD or ISO significantly increased cytotoxicity and cytokine gene expression compared to their injected primary photochemical transformation products, such as acrolein, formaldehyde and ozone for BD and methacrolein, methyl vinyl ketone, and ozone for ISO. Interestingly, exposure to the equivalent levels of ozone generated during the photochemical transformation of BD or ISO did not induce the same level of inflammatory cytokine release, suggesting that ozone alone is not the sole inducer of inflammatory responses in this system. However, for the photochemical transformation of methanol, generating primarily ozone and formaldehyde, ozone was the main inducer for both inflammation and cytotoxicity. Taken together these results indicate, that unlike simplistic atmospheric models such as methanol, ozone does not significantly account for the effects seen in more complex atmospheric mixtures, such as those generated by BD and ISO, and therefore full photochemical transformations and interactions must be carefully evaluated when investigating adverse health effects induced by exposure to HAPS.