Exposure to dimethyl selenide (DMSe)-derived secondary organic aerosol (SOA) in human airway epithelial cells (BEAS-2B)

Selenium (Se) has one of the narrowest ranges between dietary deficiency and toxic levels in humans. Through microbial transformation, plant metabolism and sea spray, Se can be volatilized and released into the atmosphere as a methylated form. Dimethyl selenide (DMSe) is one of the major volatile organoselenium compounds. The production of inhalable secondary organic aerosols (SOA) by atmospheric oxidation of DMSe and their potential health effects have not been investigated. In this study, we characterized the chemical properties of SOA generated from oxidation of DMSe with O3 and HONO and assessed the toxicological responses in cultured human airway epithelial cells (BEAS-2B). Particles were produced in controlled chamber experiments and collected onto Teflon filters. Chemical compositions of particles were monitored online using an Aerosol Mass Spectrometer (AMS). Filter samples were extracted and examined using an acellular dithiothreitol (DTT) assay to assess the oxidative potential of particles. DMSe-derived SOA showed a higher oxidative potential compared to gasoline exhaust and ambient PM. Transcriptome-wide gene expression was assessed after 24 hours of exposure. From RNA sequencing data, we found major biological pathways perturbed by DMSe-derived SOA including P53, DNA damage, TP53 network, Oxidative damage, Warburg effect, inflammatory response pathway etc. This study highlights the significance of DMSe-derived SOA as a stressor in human lung cells.