Perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoA, DTXSID50723994) is a perfluoroalkyl ether acid (PFEA) produced at a fluorochemical facility (“Fayetteville Works”) in Bladen County, North Carolina. In 2015, PFO5DoA was first identified in Cape Fear River water samples collected downstream of the facility’s wastewater discharge point.1 Approximately 280,000 people rely on public water sourced from the lower Cape Fear River.2 The GenX Exposure Study started in 2017 to characterize PFEA exposure in Cape Fear River Basin, North Carolina, residents. We detected three PFEAs—ethanesulfonic acid, 2-[1-[difluoro(1,2,2,2-tetrafluoroethoxy)methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2-tetrafluoro- (also known as Nafion by-product 2, DTXSID10892352); perfluoro(3,5,7,9-butaoxadecanoic) acid (PFO4DA, DTXSID90723993); and PFO5DoA—in blood serum from nearly all 344 participants who resided in Wilmington, North Carolina, and provided blood samples in 2017 and 2018.3
In 2018, serum samples were analyzed by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). At the time, an analytical standard for PFO5DoA was not commercially available and we were unaware of other laboratories analyzing serum for PFO5DoA, which limited interlaboratory comparison opportunities. We have since discovered a mass interference in the calibration of our PFO5DoA analysis that resulted in substantial underestimation of PFO5DoA concentrations; the other per- and polyfluoroalkyl substances (PFAS) values were not affected. This letter aims to correct previously reported serum PFO5DoA concentrations.3