Production of Perfluorinated Carboxylic Acids (PFCAs) from the Biotransformation of Polyfluoroalkyl Phosphate Surfactants (PAPS):  Exploring Routes of Human Contamination

Abstract

Perfluorinated acids are detected in human blood world-wide, with increased levels observed in industrialized areas. The origin of this contamination is not well understood. A possible route of exposure, which has received little attention experimentally, is indirect exposure to perfluorinated acids through ingestion of chemicals applied to food contact paper packaging. The current investigation quantified the load of perfluorinated acids to Sprague-Dawley rats upon exposure to polyfluoroalkyl phosphate surfactants (PAPS), nonpolymeric fluorinated surfactants approved for application to food contact paper products. The animals were administered a single dose at 200 mg/kg by oral gavage of 8:2 fluorotelomer alcohol (8:2 FTOH) mono-phosphate (8:2 monoPAPS), or the corresponding di-phosphate (8:2 diPAPS), with blood taken over 15 days post-dosing to monitor uptake, biotransformation, and elimination. Upon completion of the time-course study the animals were redosed using an identical dosing procedure, with sacrifice and necropsy 24 h after the second dosing. Increased levels of perfluorooctanoic acid (PFOA), along with both 8:2 PAPS congeners, were observed in the blood of the dosed animals. In the 8:2 monoPAPS-dosed animals, 8:2 monoPAPS and PFOA blood concentrations peaked at 7900 +/- 1200 ng/g and 34 +/- 4 ng/g respectively. In the 8:2 diPAPS-dosed animals, 8:2 diPAPS peaked in concentration at 32 +/- 6 ng/g, and 8:2 monoPAPS and PFOA peaked at 900 +/- 200 ng/g and 3.8 +/- 0.3 ng/g, respectively. Several established polyfluorinated metabolites previously identified in 8:2 FTOH metabolism studies were also observed in the dosed animals. Consistent with other fluorinated contaminants, the tissue distributions showed increased levels of both PFOA and the 8:2 PAPS congeners in the liver relative to the other tissues measured. Previous investigations have found that PAPS can migrate into food from paper packaging. Here we link ingestion of PAPS with in vivo production of perfluorinated acids.

Methodology for studying biotransformation of polyfluoroalkyl precursors in the environment

“…The MTBE aliquots were then combined, brought to dryness under a stream of nitrogen, and the polyfluorinated analytes were reconstituted in methanol. The methods were successfully applied to recover FOSAs, mono-PAPs, di-PAPs, perfluoroalkyl phosphonic acids (PFPAs) and corresponding biotransformation products in both in-vitro and in-vivo exposure studies [33,43,46,47]. Washington et al [48] also developed multi-step extraction procedures for PFCAs in soils by combining both DSPE and IPE pretreatment procedures, achieving quantitative recoveries with minimized matrix effects.…”

“…LC separation coupled with triple-quadupole MS (QqQ) detection is the most common method to analyze anionic PFASs because of its good compatibility with aqueous samples and polar extraction solvents. Perfluorinated carbon chains of PFASs (C ≥ 6) ensure appropriate retention behavior on reversed-phase stationary phases, such as C8, C18 and pentafluorophenyl (PFP) [10,29,30,43], whereas ion-exclusion chromatography was also used to separate perfluoroalkylsulfonic acids and perfluoroaklylsulfinic acids with short alkyl-chain lengths up to C4 and C6, respectively [52]. LC-MS/MS operated in the multiple-reaction monitoring (MRM) mode offered both wide linear dynamic range of at least three orders of magnitude and excellent sensitivity at sub-ppb levels.…”

PFAS in Paper and Board for Food Contact

“…PFAAs can, however, also stem from indirect sources, being PFAA precursors. These are typically polyfluorinated compounds, which have been shown to degrade to perfluorinated compounds, both abiotically and biotically, in the environment (Benskin et al 2012), during processing and upon intake (D'eon and Mabury 2007, Lee et al 2010Butt et al, 2014). Polyfluorinated substances that are taken up from food and transformed in the body into PFAAs (Danish EPA, 2015) are examples of indirect sources.…”

“…However, for the commercial PFAS, only a few studies have investigated the types and measured the levels of PFAS in paper (Begley et al 2005, D'eon and Mabury 2007, D'eon et al 2009, Lee et al 2010, Trier et al 2011a. Possibly due to the limited focus on testing the commercial PFAS, pure standards are not commercially available, which complicates method development.…”

C6-Perfluorinated Compounds: The New Greaseproofing Agents in Food Packaging

“…The 6-2 fluorotelomer iodide and the 6-2 fluorotelomer methacrylate were rapidly metabolized to C6-FTOH in rat liver microsomes [23••] and rat hepatocytes [24•], respectively. Perfluorinated FCSs, such as the perfluoroalkyl phosphate surfactants, can also be metabolized in vivo to their FTOH components and the corresponding FTOH metabolites [25]. Collectively, these data indicate that direct dietary exposure to perfluorinated FCSs or their perfluorinated monomeric precursors may produce toxic effects similar to exposure to the FTOH itself.…”