Known and Novel Per/Polyfluoroalkyl Substances (PFASs) in Serum of Tucson (AZ) Firefighters.

Per/polyfluoroalkyl substance (PFAS) exposure is a serious concern for firefighters, but the contribution of firefighting activities to overall PFAS body burden remains poorly understood. We hypothesized that overlooked novel PFASs may be elevated in firefighter serum after fire suppression activities. We analyzed paired "baseline" (annual checkup) and "postfire" (within 35 h of fire) serum from 33 members of the Tucson Fire Department using high-resolution mass spectrometry. We measured concentrations of 49 PFASs via targeted quantitation and detected 15 in >50% of samples. Concentrations of target analytes were not significantly different between baseline and postfire paired samples. However, branched PFOS isomers and linear PFHxS were significantly elevated compared to the general population. Suspect screening enabled the identification of 26 additional PFASs. Two tentatively identified phosphate-containing PFASs were significantly (p < 0.01) elevated postfire. These chemicals may be associated with exposure to fluorinated aryl phosphate flame retardants or their combustion transformation products during fire response. Several other novel PFASs were detected in baseline and postfire samples, including bis(trifluoromethylsulfonyl)imide (bis-FMeSI). The presence of novel PFASs in serum from firefighters highlights the need for more research into their occurrence in occupationally exposed groups and the general population, exposure sources, and toxicokinetics.