Spatiotemporal Distribution of 6PPD-Q in China Revealed by a National-Scale Quantification Framework

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), an oxidation hazardous derivative of the tire antioxidant 6PPD, has emerged as a ubiquitous contaminant with significant ecotoxicity and health risks. Despite growing concern, large-scale spatiotemporal emission dynamics, multimedia environmental fate, and exposure levels remain unclear. Here, we established a nationwide quantitative assessment framework integrating high-resolution emission inventories, multimedia environmental fate modeling, and multi-pathway human exposure analysis to delineate the spatiotemporal dynamics of 6PPD-Q pollution and associated exposure risks in China. Results reveal that national 6PPD-Q emissions increased by ∼97.5% from 2013 to 2023, primarily driven by vehicular expansion. Source partitioning reveals disproportionate contributions from highway traffic and soil reservoirs, underscoring the need to extend monitoring beyond urban water environments. Modeled concentrations highlight densely populated and topographically constrained regions as pollution hotspots. Exposure assessment reveals that the estimated daily intake of 6PPD-Q is higher in children (0.006-0.011 ng/(kg·day)) than that in adults (0.003-0.005 ng/(kg·day)), with soil ingestion identified as the primary exposure route. This framework provides an efficient approach for quantitatively assessing 6PPD-Q pollution, supporting its risk evaluation and regulatory interventions.