The last straw: Characterization of per- and polyfluoroalkyl substances in commercially-available plant-based drinking straws

Abstract

Paper and other plant-based drinking straws are replacing plastic straws in commercial settingsin response to trending plastic straw bans and the larger global movement for reducing plastic pollution. The water-resistant properties of many plant-based straws, however, may be attributed to the use of per- and polyfluoroalkyl substances (PFAS) during manufacturing. In this study, 43 brands of straws (5 plastic, 29 paper, 9 other plant-based) were analyzed for the presence of 53 semi-volatile PFAS using ultra high-performance liquid chromatography tandem mass spectrometry. While the plastic straws had no measurable PFAS, 21 PFAS were detected in the paper and other plant-based straws, with total mean PFAS concentrations (triplicate analysis) ranging from 0.043 ± 0.004 ng/straw to 29.1 ± 1.66 ng/straw (median = 0.554 ng/straw). Perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA) were the most frequently detected species. In a follow-up experiment, the brand with the highest PFAS levels and most diversity was tested for leaching in water at initial temperatures of 4 °C, 20 °C, and 90 °C. Approximately 2/3 of the total extractable PFAS leached compared to the initial methanol extraction. Semi-volatile PFAS concentrations measured in this study may be the result of manufacturing impurities or contamination, as PFAS approved for food-contact use are, typically, polymeric species. The presence of PFAS in plant-based drinking straws demonstrates that they are not fully biodegradable, contributing to the direct human ingestion of PFAS and to the cycle of PFAS between waste streams and the environment.