Observation of a Commercial Fluorinated Material, the Polyfluoroalkyl Phosphoric Acid Diesters, in Human Sera, Wastewater Treatment Plant Sludge, and Paper Fibers

Abstract

Sources of human exposure to perfluorinated carboxylic acids (PFCAs) are not well-characterized. Polyfluoroalkyl phosphoric acids (PAPs) are fluorinated surfactants used in human food contact paper products. PAPs can migrate into food and food simulants, and their bioavailability and biotransformation into PFCAs has been demonstrated using a rat model. To characterize human exposure to PAP materials, we analyzed pooled human sera samples collected in 2004 and 2005 (n = 10) and 2008 (n = 10) from the midwestern United States for the 4:2 through 10:2 PAP diesters (diPAPs). The 2004 and 2005 sera samples contained 4.5 microg/L total diPAPs, with the 6:2 diPAP dominating the congener profile at 1.9 +/- 0.4 microg/L DiPAP concentrations observed in the 2004 and 2005 human sera samples were similar to those of the C8 to C11 PFCAs (0.13 +/- 0.01 to 4.2 +/- 0.3 microg/L) monitored in the same samples. 6:2 diPAP was also consistently observed in the 2008 human sera samples at a mean concentration of 0.63 +/- 0.13 microg/L As diPAPs have been shown to degrade to PFCAs in vivo, our observation of diPAPs in human sera may be a direct connection between the legacy of human PFCA contamination and PAPs commercial applications. Wastewater treatment plant (WWTP) sludge and paper fibers were analyzed for diPAPs as a proxy for human use and potential exposure to diPAPs. DiPAPs were observed in WWTP sludge at concentrations ranging from 47 +/- 22 to 200 +/- 130 ng/g, a range similar to perfluorooctane sulfonic acid (PFOS) (100 +/- 70 ng/g) and greater than the C8 to C11 PFCAs (1.6 +/- 0.6 to 0.17 +/- 0.10 ng/g) observed in the same samples. DiPAPs were observed in paper fiber extracts at concentrations ranging from 34 +/- 30 to 2200 +/- 400 ng/g. The high diPAP concentrations in WWTP sludge suggest PAP materials may be prevalent in our daily lives.

Methodology for studying biotransformation of polyfluoroalkyl precursors in the environment

“…An additional 10-20% of 14 Clabeled polyfluoroalkyl transformation products was recovered from soil initially dosed with 14 C-labeled 8:2 FTOH when the DSPE extraction temperature was elevated to 50°C [29]. D'eon et al [16] also found that the removal of sodium-carbonate buffer in the IPE procedures minimized 8:2 diPAP blank contamination in the analysis of mono-PAP and di-PAP concentrations in human-serum samples with adequate extraction efficiencies (85 ± 22%).…”

“…Soil is the primary deposit medium of volatile precursors through atmospheric deposition, while sewage sludge and river sediment are important sinks of PFASs in aqueous systems from household and industry emissions [15][16][17]. To obtain knowledge on the specific microorganisms responsible for the polyfluoroalkyl precursor biotransformation processes, microbial consortium or pure bacterial cultures from soil and sewage sludge were isolated and used [30][31][32].…”

“…Both fluorotelomer-based (FT) precursors (e.g., FTOHs and FTIs) and perfluoroalkane sulfonamido derivatives, including N-ethyl perfluorooctane sulfonamide (N-EtFOSA) and N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE), were found in ambient air particles [13][14][15]. Fluorotelomer alcohols, monosubstituted and disubstituted PAPs, and perfluorooctane sulfonamidoacetic acid (FOSAA) analogues have frequently been detected in wastewater-treatment plant (WWTP) effluent, activated sludge and marine sediments [15][16][17]. Elevated PFAS concentrations found in effluents compared with those in influents may further indicate contributions of polyfluorinated-precursor biodegradation in the WWTPs [18].…”

Occurrence of organic microcontaminants in the wastewater treatment process. A mini review

“…But even if they seldom appear in quantifiable limits, some studies advocate that precursors do play an important role in the levels of PFOS found in WWTP effluents and increases in its mass flow were found after activated sludge treatment in facilities from all over the world [97][98][99][100]. Rhoads et al [101] found three potential precursors (perfluorooctanesulfonamide (PFOSA), methyl perfluorobutane sulfonamine (MeFBSA) and methyl perfluorobutane sulfonamidoethanol (MeFBSE)) in WWTPs and D'Eon et al [102] stated the possibility of 4-carbon-chain (C4) compounds like MeFBSA and MeFBSE degrading into the C4 homologues of perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs). Some researchers reported that laboratory experiments supported the field studies and concluded that aerobic microbial biodegradation of precursors can yield important loads of PFCs [101], but the actual understanding of these processes is still weak.…”

Trends of polyfluoroalkyl compounds in marine biota and in humans

“…[67] Recently, polyfluoroalkyl phosphoric acids (PAPs) were detected in human blood. [68] PAPs are fluorinated surfactants used in human food contact paper products. In 2004-05 their concentrations in US human serum were ,4.5 mg L À1 in total.…”