Linking Inorganic Constituents of Ambient PM2.5-0.1 to In-Vitro Toxicological Effects

DAVID HEALY (1), Virginia Silvari (1), José Lopez (1), Andrew Whittaker (1), Emma Peré-Trepat (1), John Wenger (1), James J. A. Heffron (1) and John R. Sodeau (1)

(1) University College Cork

     Abstract Number: 25
     Last modified: September 30, 2009

Abstract
Background: Adverse health effects associated with exposure to airborne particulate matter (PM) can be seasonally dependent due to the variation in (bio-)chemical composition. Objectives: We tested the hypothesis that differences in the inorganic constituents of PM2.5-0.1 maybe responsible for seasonal variations in adverse health effects. Methods: Ambient fine PM (PM2.5-0.1) was collected over a two year period at city centre, urban background and rural sites in Cork, Ireland. Human lung epithelial cells, A549, were exposed to the extracted PM2.5-0.1 and the release of interleukin IL-6, IL-8, TNF-alpha and the generation of intracellular reactive oxygen species (ROS) were measured along with cytotoxicity. The results were correlated with chemical composition determined by IC and ICP-AES. Results: At all sites, the summer season collections were found to be the most acidic and the most potent for the induction of IL-6. In contrast, no obvious seasonal trend was observed for ROS generation, although its highest levels were stimulated by samples from the urban and urban background sites. Principal Component Analysis (PCA) performed on both elemental constituents and toxicological endpoints identified four factors, which group together: (i) ROS with transition metals; (ii) crustal/soil derived elements with cytokine and cytotoxicity; (iii) secondary inorganic species with ROS, IL-6 and LDH; (iv) total carbon, hydrogen content, Ti and Al with cytotoxicity/LDH. Conclusions: The complementary analytical, toxicological and chemometric results obtained indicate that heterogeneous mixtures of certain metals present in PM2.5-0.1 matrices along with inorganic ions, which control acidity, could indeed be partly responsible for seasonal, PM-induced health effects associated with respiratory illnesses.