Source profiles of PM2.5 emitted from four typical open burning sources and its cytotoxicity to vascular smooth muscle cells.

This study investigated the chemical profiles of PM2.5 from open burning of electronic waste (E-waste), household garbage, wheat residue, and outdoor barbeque in a combustion chamber. Carbonaceous fractions, including polycyclic aromatic hydrocarbons (PAHs), and water-soluble ions and elements in PM2.5 were quantified. A PM2.5 exposure study was performed to detect PM2.5-induced bioreactivities in vascular smooth muscle cells (VSMCs). Among all fractions, organic carbon (OC) exhibited the highest mass contribution to PM2.5-ranging from 39.9% ± 0.82% to 53.1% ± 8.76%. Proportions of total water-soluble ions and total elements both followed the sequence E-waste > wheat straw > outdoor barbeque > household garbage. Because of the high burning temperature, outdoor barbeque PM2.5 exhibited the highest total quantified PAHs (29.7‰). E-waste PM2.5 exhibited the highest heavy metal contents, derived mainly from the materials in printed circuit boards. The coefficients of divergence among the four source profiles ranged from 0.47 to 0.75, indicating that the collinear problems could be avoided in source apportionment in receptor models. The induced production of reactive oxygen species exhibited a significant dose-dependent increase and followed the sequence E-waste > household garbage > outdoor barbeque > wheat residue. Similar patterns and sequence among the four sources were observed in monocyte chemoattractant protein 1 (MCP-1) and interleukin 1β (IL-1β) production. The data indicated that PM2.5 emitted from E-waste has the highest cytotoxicity and special protections should be aimed at mitigating it. The Pearson correlation coefficient demonstrated that elemental carbon, heavy metals, and nitrated PAHs were strongly correlated with VSMC bioreactivity. Light elements exhibited moderate negative correlations with bioreactivities, implying that light elements (e.g., Ca) could mitigate heavy metal-induced cytotoxicity. This study summarized the chemical profiles of PM2.5 from four typical open burning sources and demonstrated their high cytotoxicity to the cardiovascular system.