Unveiling Condensed Aromatic Amines as Noteworthy Genotoxic Components in PM2.5 Dissolved Organic Matter

The potential of PM_2.5 to cause lung cancer has been well established; however, evidence regarding which specific components are responsible remains limited. We investigated dissolved organic matter (DOM) in PM_2.5 using high-resolution mass spectrometry (HRMS) and cellular DNA damage assays to elucidate molecular composition and sources of carcinogenic components. Our analysis revealed hundreds of genotoxic compounds, with condensed aromatic amines predominating in number, abundance, and contribution to overall genotoxicity. Notably, norharman, a heterocyclic aromatic amine, was identified as a key carcinogenic component. Genotoxicity analysis using a lung cell exposure model indicated that, based on the measured concentration ratio of norharman to benzo[a]pyrene in DOM, the genotoxicity of norharman was approximately 0.21 to 0.6 times that of benzo[a]pyrene. Compared to proinflammatory compounds, these carcinogenic compounds exhibited greater unsaturation, increased aromaticity, an augmented reduced state, and the presence of nitrogenous organic matter. Two-ring aromatic amines containing two nitrogen atoms were identified as key contributors to both inflammation and genotoxicity. Regional source apportionment revealed significant regional variability in condensed aromatic amines within PM_2.5. While polycyclic aromatic hydrocarbons (PAHs) are significant, condensed aromatic amines also warrant consideration in PM_2.5 management. Effective mitigation requires tailored prevention measures based on regional pollution profiles and health impacts.