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Evolving Toxicity Of Heterogeneously Oxidized Benzo[a]pyrene Aerosol Particles
AMY HRDINA, James Rowe, Simran Kaushal, Bevin Engelward, Jesse Kroll, MIT
Abstract Number: 89
Working Group: Aerosol Chemistry
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are a class of chemical pollutants formed by incomplete combustion. PAHs are known carcinogens and mutagens. While atmospheric oxidation degrades PAHs, it may also lead to the formation of toxic secondary products, modulating their health impacts in important but poorly understood ways. To better elucidate the products formed from these degradation reactions, environmental chamber studies were conducted on the heterogeneous oxidation of particle-phase benzo[a]pyrene (BaP). BaP-coated ammonium sulfate aerosol particles (BaP-AS) were exposed to two common atmospheric oxidants, ozone (O3) and OH. Reaction products and kinetics were investigated by measuring the evolving particle-phase composition with an Aerosol Mass Spectrometer (AMS). The major products observed in both reaction systems include BaP-dione isomers (C20H12O2), BaP-lactone (C19H10O2), and BaP-epoxide or diol (C20H12O). The reaction with OH yielded more oxygenated compounds than the reaction with O3, suggesting OH reacts with both first- and second-generation products. Toxicity studies of BaP-AS collected from chamber experiments were examined using the high-throughput ‘CometChip’ assay to quantify DNA damage. Preliminary results show exposure to untreated BaP-AS exhibited increased DNA damage with increased dosage, similar to the BaP control standard. The change in toxicity of oxidized BaP-AS was measured as a function of oxidant exposure. Differences in DNA damage was related to observed changes in aerosol particle composition.