Environmental relevance of 6PPD-quinone. (A) Using retrospective UPLC-HRMS analysis of archived sample extracts, 6PPD-quinone was quantified in roadway runoff and runoff-impacted receiving waters. Each symbol corresponds to duplicate or triplicate samples, boxes represent first and third quartiles. For comparison, the 0.8 pg/L LC50 value for juvenile coho salmon and detected 6PPD-quinone levels in 250 and 1000 mg/L TWP leachate are included. (B) Predicted ranges of potential 6PPD-quinone mass formation in passenger cars (e.g., 4 tires, -36 kg tire rubber mass) and heavy trucks, (e.g., 18 tires, -900 kg of tire rubber) (represented in orange) and measured 6PPD-quinone concentrations in affected environmental compartments (represented in blue, with experimental data italicized). Predicted ranges reflect calculations applying 0.4-2% 6PPD per total vehicle tire rubber mass followed by various yield scenarios (1-75% ultimate yields) for 6PPD reaction with ground-level ozone to form 6PPD-quinone. Graphic: Tian, et al. / Science