Identification of Major Metabolic Disruption Chemicals in PM_2.5 from a Chinese Megacity

The adverse health effects of fine particulate matter (PM_2.5) depend strongly on its chemical composition, yet the specific organic components responsible for its toxicity remain insufficiently elucidated. To identify potential toxic constituents in PM_2.5, we collected sixty-two PM_2.5 samples from Chongqing, a typical basin city in China, and characterized their chemical composition and toxicity by coupling nontargeted analysis (NTA) with metabolomics. The results revealed 382 organic compounds, with significant seasonal variations, such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives. Exposure of BEAS-2B human lung epithelial cells to PM_2.5 extracts induced significant perturbations in energy, nucleotide, and redox metabolism, with winter samples exhibiting greater toxicity compared to summer samples. A total of 59 pollutants were significantly correlated with extensive metabolic alterations, especially heteroatom-containing and aromatic chemicals. Fifteen pollutants, including typical PAHs and emerging derivatives (e.g., dinaphtho[2,1-b:1',2'-d]furan, 2-methylnaphthalene, and 11H-benzo[a]fluoren-11-one), were prioritized by sparse partial least-squares regression as candidate contributors. We further validated these associations by testing the metabolic disruption effects of individual chemicals and quantifying their contributions to the overall PM mixture effects. Notably, 7H-benz[de]anthracen-7-one and pyrene jointly accounted for 80% of the PM-associated decrease in 2-Thiocytidine, a metabolite involved in nucleotide metabolism. This study offers new insights into the chemical-specific toxicity of PM_2.5 and highlights the role of PAHs in cellular metabolic disruption by NTA-Metabolomics pairing and experimental validation.