Linking Polycarbonate Plastics to Perfluorobutanesulfonate Emissions in Landfill Leachates via Suspect and Nontarget Screening of Diverse Plastic Products

Driven by strict global regulations on legacy per- and polyfluoroalkyl substances (PFAS), short-chain alternatives such as perfluorobutanesulfonate (PFBS) are increasingly used, resulting in widespread environmental detection, notably at elevated concentrations in landfill leachates, while emission sources remain uncertain. Plastics, recognized as reservoirs of numerous chemical additives with documented but rarely investigated PFAS usage, represent a potential unidentified source. Here, 105 plastic products representing 11 types of polymers were analyzed, with 20 PFAS from 6 classes identified (confidence levels of 3 or better). Polycarbonate (PC) exhibited the highest average total PFAS concentration (713 ng/g), primarily dominated by PFBS (97%), reaching up to 6130 ng/g. PFBS, commonly co-occurred with a monohydrogen-substituted PFBS (H-PFBS), particularly enriched in PC components from electronic products, indicating intentional use as flame retardants. Consistent PFBS to H-PFBS peak area ratios observed in PC samples (∼4%) and industrial PFBS products (0.07-3%), along with patent records, suggest H-PFBS as a manufacturing impurity. Simulated leaching experiments in a realistic scenario showed rapid migration of PFBS and H-PFBS into both freshwater and seawater, achieving equilibrium releases up to 39% within 14 days. Annual PFBS emissions from PC plastics to landfill leachates in China were estimated at ∼40 kg, contributing ∼10% of the total landfill-derived PFAS flux. These findings identify that PC plastics may represent a previously underrecognized contributor to PFBS contamination in landfill leachates, emphasizing the urgent need for safer plastic additives and enhanced waste management.