Fluorine mass balance studies have shown that monomeric per- and polyfluoroalkyl substances (PFAS) with perfluoroalkyl chain lengths of ∼5–14 carbon atoms (i.e., “conventional” PFAS) account for a fraction (∼2%) of the extractable organic fluorine (EOF) in municipal wastewater treatment plant (WWTP) sludge. The identity of the remaining EOF has thus far been unclear but may be partly attributable to fluorine-containing pharmaceuticals and pesticides used throughout society. To test this hypothesis, we applied high resolution mass spectrometry-based suspect screening to samples of municipal WWTP sludge which had been previously subjected to a fluorine mass balance. Sixteen pharmaceutical substances (including transformation products [TPs]), one pesticide, and thirteen conventional PFAS were confirmed at confidence levels 1–4 and (semi)quantified, revealing concentrations ranging from 0.07 to 155 ng/g dw. Notably, eight pharmaceutical substances did not meet the OECD definition of PFAS. When converted to fluorine equivalents, the newly detected organofluorine substances increased the percentage of known EOF from ∼2% to ∼27%, of which ∼22% was attributed to pharmaceutical and pesticide substances, with the greatest contributions from ticagrelor TP (4.0%), ezetimibe (3.9%), and bicalutamide (3.5%). These data highlight the importance of considering both unconventional and non-PFAS organofluorine substances in addition to conventional PFAS when closing the organofluorine mass balance in WWTP sludge.

Fluorine mass balance studies have shown that monomeric per- and polyfluoroalkyl substances (PFAS) with perfluoroalkyl chain lengths of ~5-14 carbon atoms (i.e., “conventional” PFAS) account for a fraction (~2%) of the extractable organic fluorine (EOF) in municipal wastewater treatment plant (WWTP) sludge. The identity of the remaining EOF has thus far been unclear, but may be partly attributable to fluorine-containing pharmaceuticals and pesticides used throughout society. To test this hypothesis, we applied high resolution mass spectrometry-based suspect screening to samples of municipal WWTP sludge which had been previously subjected to a fluorine mass balance. Sixteen pharmaceutical substances (including transformation products [TPs]), one pesticide, and thirteen conventional PFAS were confirmed at confidence levels 1-4, with concentrations ranging from 0.07-155 ng/g dw. Notably, eight pharmaceutical substances did not meet the OECD definition of PFAS. When converted to fluorine equivalents, the newly detected organofluorine substances increased the percentage of known EOF from ~2% to ~27%, of which ~22% was attributed to pharmaceutical- and pesticide substances, with the greatest contributions from a ticagrelor TP (4.0%), ezetimibe (3.9%), and bicalutamide (3.5%). These data highlight the importance of considering both unconventional- and non-PFAS organofluorine substances in addition to conventional PFAS when closing the organofluorine mass balance in WWTP sludge.