[P3709] Oxidative capacity as a new metric for the monitoring of ambient particulate matter(PM)

Tingming Shi,¹ Roel P. F. Schins,¹ Ian S. Mudway,² Luis A. Jimenez,³ Frank J. Kelly,² Nino Kunzli,⁴ Ken Donaldson,³ Thomas Kulhbusch,⁵ Paul J. A. Borm.¹. ¹IUF, Duesseldorf, Germany; ²Kings College, London, United Kingdom; ³ELEGI, Edinburgh, United Kingdom; ⁴UCLA, Los Angeles, United States of America; ⁵IUTA, Duisburg, Germany

Free radical generation by ambient particles (PM) has been suggested as a unifying factor in biological activity. We compared the oxidant activity of PM using several methods: (1) Electron spin resonance(ESR) to quantify hydroxyl radical formation (2) DNA oxidation in A549 cells (3) DNA unwinding in supercoiled DNA (4) depletion of antioxidants in a synthetic respiratory tract lining fluid model. Parallel samples of PM₁₀, PM_2.5 and PM₁ collected in Duisburg, all induced hydroxyl radical (•OH) formation in the presence of H₂O₂, and consumed both ascorbate and reduced glutathione in the absence of H₂O₂ . For all endpoints the greatest activity was observed in the PM₁ fraction. The •OH generation by PM subfractions correlated with their capacity to degrade both ascorbate (r=0.56) and GSH (r=0.92) or to cause plasmid DNA damage (r=0.74). The •OH generation of coarse and fine PM was correlated to DNA damage in A549 cells. The temporal and regional variation in particle oxidant activity was examined by analysis of PM_2.5 collected from 20 European sites over a two year time frame. Moreover, oxidant activity of PM from several German cities was related to airway resistance in children living in these cities. In conclusion, we propose that oxidant activity of PM can be an alternative metric that is more closely related to the biological effects caused by PM. Keywords: occupation, pollution; inflammation