AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Source, Size and Seasonal Differences in the Biological Potency of Ambient Particulate Matter Collected at Three Different Locations across Canada
SUBRAMANIAN KARTHIKEYAN, Dalibor Breznan, Errol Thomson, Yunus Siddiqui, P. Goegan, Michael Denison, P. Kumarathasan, Jeff Brook, Renaud Vincent, Hazard Identification Division, HECSB, Health Canada
Abstract Number: 566 Working Group: Health Related Aerosols
Abstract Population studies have shown that the health effects of particulate air pollution vary depending on location, season, and particle size. The objectives of this work are to better understand the impact of particle characteristics on cytotoxicity and inflammatory potential in vitro, to summarize dose-responses observed in a panel of endpoints into biological potency estimates, and to assess the value of potency estimates as predictors of population health risk. Concurrent PM10 and PM2.5 samples were collected at Downsview (Ontario), Saint John (New Brunswick), and Pitt Meadows (British Columbia) in summer and winter. Particles were extracted from filters and analyzed for cytotoxicity and inflammatory potential in epithelial-like A549 cells, and macrophage-like J774A.1 cells. The potency of particles was determined according to Fold effect = (Dose + 1)$^beta, where beta is the slope of the dose-response relationship. It was also tested if factoring particle potency estimates would improve the correlation between exposure (ambient particle concentration used as a surrogate) and rates of adverse health outcomes. Cytotoxicity was significantly impacted by location (p<0.05), with particles from Pitt Meadows being the most potent. Secretion of inflammatory cytokines was impacted by both location and season. PAH ratios pointed to domestic fuel combustion in Pitt Meadows, and automotive combustion in Downsview and Saint John, as dominant sources. The elements Ag, Bi, Cu, Ti, and Zn emerged as drivers of cytotoxicity. Overall, the biological potency of ambient particles was impacted by the location and season of sampling, and was related to the physicochemical characteristics of particles. Nevertheless, the correlation between particle concentration and health outcomes was not improved by the incorporation of potency estimates into the calculation of risk. Potency data from a larger number of ambient PM samples may be required to fully validate the application of potency measurements in the refinement of population health risk estimates.