Polycyclic aromatic hydrocarbons (PAHs), a class of chemical pollutants formed by incomplete combustion, 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 probe how such oxidative processes may augment or suppress the toxicity of PAHs, 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 (O<sub>3</sub>) and OH. Reaction products 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). Toxicity studies of BaP-AS collected from chamber experiments were examined using the high-throughput ‘CometChip’ assay to quantify DNA damage on two different cell types, liver derived (HepaRG) and blood derived (TK6). Results show exposure to unoxidized BaP-AS exhibited increased DNA damage with increased dosage, similar to the BaP control standard only for the liver-based cells with metabolic enzymes (i.e., CYP450). However, both standard PAH product mixtures (i.e. parent BaP, 1,6- and 3,6-quinones, and BaP diol epoxide), and oxidized BaP-AS samples exhibited a different dose response compared to pure BaP alone, in which no damage was observed to liver-based cells, and a significant dose response was apparent for blood-derived cells. The extent of DNA damaging potential, as a function of oxidant type, exposure, and aerosol composition, provides insight into the evolving toxicity of PAHs over their atmospheric lifecycle and their potency and potential for human relevance.

Effects of atmospheric oxidation on benzo[a]pyrene aerosol particles: Mutagenicity and potential health effects

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.