Fluorinated aromatic PBCTF and 6:2 diPAP in bridge and traffic paints†

Abstract

Per- and polyfluoroalkyl substances (PFAS) are reported in residential and commercial paints, but there are no data for paints used in the transportation sector. From 2023 to 2024, 16 traffic paints and 10 bridge paints were collected from Pacific Northwest regional transportation facilities or purchased and analyzed for total fluorine by ¹⁹F-nuclear magnetic resonance (NMR) spectroscopy, volatile PFAS by gas chromatography-mass spectrometry (GC-MS), and ionic target and suspect PFAS by liquid chromatography-quadrupole time-of-flight mass spectrometry. The only target PFAS identified was 6:2 fluorotelomer phosphate diester (diPAP) which ranged in concentrations from 0.065 to 13 μg g⁻¹. While 6:2 diPAP is not regulated in paints, it can undergo environmental transformation to act as a source of perfluoroalkyl carboxylic acids. A combination of ¹⁹F-NMR and GC-MS was used to quantify and identify the fluorinated aromatic PFAS, parachlorobenzotrifluoride (PCBTF), at concentrations from 440 to 16 000 μg g⁻¹ in bridge paints, thus PCBTF may contribute to work exposure and levels in urban air. Additionally, evolved gas analysis with mass spectrometry and pyrolysis-GC-MS established that the insoluble fraction of paints is not comprised of fluoropolymers. Based on the amount of paint required per kilometer, we estimate up to 0.20–2.30 g 6:2 diPAP per kilometer depending on marking type. Therefore, traffic paint may be a potential source of the PFAS detected in urban runoff.