Unsaturated PFOS and Other PFASs in Human Serum and Drinking Water from an AFFF-Impacted Community

Abstract

Understanding how exposure to aqueous filmforming foam (AFFF)-impacted drinking water translates to bioaccumulation of per-and polyfluoroalkyl substances (PFASs) is essential to assess health risks. To investigate spatial variability of PFAS exposure in communities near an AFFF source zone, blood serum was collected in 2018 from 220 adult residents of El Paso County (Colorado), as were raw water samples from several wells. C6 and C8 perfluoroalkyl sulfonates (PFSAs) were predominant in serum and water. PFASs were most elevated in the water district nearest the source zone (median ∑PFSA of 618 ng/L in water and 33 ng/mL in serum). A novel PFAS, unsaturated perfluorooctane sulfonate, was detected in >80% of water and serum samples at low concentrations (≤1.9 ng/mL in serum). Drinking water wells nearest the source zone displayed increased prevalence of perfluoroalkyl sulfonamide precursors not detected in serum. Serum-towater ratios were the greatest for long-chain PFASs and were elevated in the least impacted water district. Additional serum samples collected from a subset of study participants in June 2019 showed that PFAS concentrations in serum declined after exposure ceased, although declines for perfluoropentane sulfonate were minimal. Our findings demonstrate that AFFF-impacted communities are exposed to complex, spatially variable mixtures of PFASs.

Communicating Confidence of Per- and Polyfluoroalkyl Substance Identification via High-Resolution Mass Spectrometry

“…Therefore, other complementary data in the MS/MS spectra (e.g., the presence or absence of fragments at m / z = 79.96, 230.99, and/or 280.98) are necessary for these fragments to be considered diagnostic ( Figure 3 ). 38 …”

Widening the Lens on PFASs: Direct Human Exposure to Perfluoroalkyl Acid Precursors (pre-PFAAs)

“…Pre-PFAAs may be transformed to PFAAs during transport prior to reaching drinking water intakes, resulting primarily in indirect exposure. Pre-PFAAs can transform abiotically through hydrolysis and photolysis − and may transform during drinking water treatment. , Some fairly persistent ionizable pre-PFAAs such as fluorotelomer sulfonates (FTSs) and FASAs have been intermittently detected at low levels (typically <5 ppt) in drinking water. , Sites of AFFF use or PFAS manufacturing often contain significant amounts of pre-PFAAs ,, and contribute PFAS contamination to drinking water sources. , However, studies of PFAS transport from AFFF-contaminated source zones demonstrate that many novel pre-PFAAs (particularly zwitterions and cations) are not likely transported far from AFFF source zones prior to transformation. , These pre-PFAAs may transform to mobile intermediate pre-PFAAs such as FASAs. FASAs were widespread in drinking water wells in a recent study of an AFFF-impacted community in Colorado Springs …”

“…Progress in this area will greatly improve understanding of the importance of human exposure to pre-PFAAs and will contribute to closing the mass balance on organofluorine in human blood. Total organic fluorine measurements indicate the likely presence of unknown PFASs in human blood from the general population, , but only a handful of novel PFASs have been identified in human serum. ,− The presence of unidentified pre-PFAAs, including intermediate transformation products, has been raised as a potential contributor to the unknown PFAS fraction in serum from the general population …”

An Overview of the Formation of PFOA and PFOS in Drinking-Water and Wastewater Treatment Processes

“…Two primary PFAS, namely perfluorooctanoic acid (PFOA) (C 7 F 15 COOH) and perfluorooctane sulfonate (PFOS) (C 8 F 17 SO 3 H), have been measured in drinking water around the globe at concentrations ranging from a few to several tens of ng/L (Andrews and Naidenko 2020;Ericson et al 2009;Eschauzier et al 2012;Hoffman et al 2011;Hölzer et al 2008;McDonough et al 2021;Quinones and Snyder 2009;Takagi et al 2011;Xiao 2017). They are not readily removed by conventional drinking-water treatment processes and are stable against physical and chemical degradation at circumneutral pH (6-9) (Eschauzier et al 2012;Rahman et al 2014;Schröder and Meesters 2005;Takagi et al 2011;Xiao et al 2013).…”