Trier et al 2017 gives an excellent review of PFAS paper coatings

Each mixture typically contains from 3-20 structurally different molecules.

..many fluorotelomer paper coatings/additives are mixtures of C 6 , C8 , C 10 and C 12 fluorochemicals, where the C 8 and higher fluorochemicals are potential candidates for biodegradation (Begley 2005)

Examples of widely used polyfluorinated PFAA precursors .. include FTOHs and their derivatives, which degrade to form perfluorocarboxylic acids (PFCAs). In paper and board, examples are the polyfluorinated alkyl phosphate esters (PAPs), fluorotelomer mercaptoalkyl phosphate diesters (FTMAPs) (Begley et al, 2005, Trier et al. 2011) and fluorotelomer acrylates..

..as the FTOH-derived PFAS dominate the US FDA and the BfR lists of approved PFAS for food paper coatings, they constitute a solid starting point for the analysis of PFAS in food paper

Note that most precursors degrade to PFCAs, including acrylate linked fluorotelomer polymers (Washington 2015).

Lee and Mabury, 2011

Lee and Mabury show structures of diPAP, FTMAP, SamPAP.

The fluorotelomer mercaptoalkyl phosphate esters (FTMAPs) have been commercialized for use in food packaging in the United States (U.S.) since 1995.

No published literature on the fate of FTMAPs is known, but one possible degradation pathway is cleavage of the carbon#sulfur bond to release the fluorotelomer appended to the cyclic phosphate moiety, which upon further oxidation, may yield either FTOH or FTS depending on which side of the sulfur atom the cleavage occurs.

Production of FTS by degradation of FTMAP was later proven experimentally (Bugsel 2023)

Only 4 Oneida County wells detected significant 6:2 FTS and I was not initially impressed by this small number. But on the other hand only 21 samples were apparently tested for it, presumably due to variation in the target list by laboratory.

Furthermore, these wells were 3 of the top 4 wells in the DNR well data portal for the entire state (594 samples tested for it). The fourth well was apparently municipal well #11 in Madison, which showed ‘no detect’ for FTS when retested a few months later. I also looked at the La Crosse airport data for instances of 6:2 FTS. Three residential wells had comparable levels out of 550 samples, about half of which are west of the airport in the apparent path of the PFOA plume from the terminal apron.

This low occurrence rate may be explained by the short half life of FTS under aerobic conditions (Wang 2011).

Thus, the presence of FTS in the groundwater may be an important indicator of the identity of the precursor.

Bugsel 2022

Bugsel sampled soil contaminated by spreading of pulp mill sludge as fertilizer. He comments on the FTS found there.

The occurrence of FTSAs in five soil samples (S9, S11–14) further indicates a past FTMAP contamination of which only the degradation products are still visible. But also, direct FTSA discharge or contamination of so far unidentified precursors which may also form FTSAs has to be taken into consideration.

FTMAPs have been so far infrequently detected in the environment, e.g., 8:2 FTMAP in 1 out of 7 samples of landfill leachates below the LOQ (2 ng/L). Despite high production volumes and application to consumer products, the rare FTMAP detections may be due to faster degradation than other PFAS precursors and low mobility (hydrophobicity).

Commercial PFAS products typically contain homologue patterns from the industrial synthesis which may vary depending on manufacturer and batch, and are therefore useful as a sort of fingerprint. FTMAPs range from 6:2/6:2 to 10:2/10:2 and are typically found in commercial products for paper impregnation like Lodyne P208E

(Trier et al. 2011).

Figure 2 shows the extracted ion chromatograms of five FTMAP homologues and their

characteristic retention time shifts. Their identity has been confirmed by accurate mass, accurate mass fragments, and retention time of the synthesized 6:2/6:2 FTMAP (ESM1). In addition to the occurrence of FTSAs as byproducts in paper, FTSAs may be break-down products of FTMAPs [34], which are formed by cleavage of the carbon-sulfur bond and further oxidation of the thiol group of the fluorotelomer side chain.

Langberg 2021

Lake sediment favored longer FTS chain lengths: a bit more 10:2 than 12:2

Leachate from the paper sludge in the landfill was weighted equally toward 8:2/10:2 FTS; creek sediment shifted toward 8:2.

The authors theorized that the lake sediment received PFAS adsorbed by paper fibers.

With longer chain lengths generally binding more strongly to solids, it would make sense that leachate from the same waste would favor lower chain lengths. Thus, getting biosolids contaminated soil *or* paper mill sludge from a landfill would give a better idea of what was used in production than looking at leachate water or associated sediment. (Or in the case of Stella, groundwater.)

The fact that longer chain lengths led to PFOA dominating the resulting water samples is totally consistent with what we see in Stella, where in the most heavily contaminated wells PFOA was the dominant carboxylate.

For this reason it is recommended that the soil method be extended to longer FTS chain lengths for this purpose, or consideration should be given to working on a non-targeted method along the lines of Bugsel, who only needed a standard for one homologue in each series. In either case, I would suggest some sort of total organic fluorine analysis to check for the presence of precursors/intermediates not revealed by the chosen method.

Having surfed several paper company websites – most of which tout their packaging paper - it seems likely that Rhinelander/Stella is only the tip of a large iceberg. Investments made now to identify common paper industry precursors seem likely to yield dividends for many years.

EPA Multi-Industry Report (9/2021)

EPA and representatives from Ahlstrom-Munksjö discussed the company’s operations at two pulp and paper mills and two specialty paper manufacturing facilities in Wisconsin.

Ahlstrom-Munksjö became a member of AF&PA after the trade association’s PFAS survey was conducted and their facilities are not included the survey results. As of July 2021, the four Ahlstrom-Munksjö Wisconsin facilities are applying coatings containing PFAS to impart oil and grease resistance to food service products. Two copolymer coatings, supplied by Daikin and Solvay, contain FDA-approved PFAS and are applied to finished sheets in a closed-loop, recirculating system (excess coating is captured and reused). To Ahlstrom-Munksjö’s knowledge, no wastewaters are generated during the coating process. Ahlstrom-Munksjö estimated that approximately 10 percent of production at the four Wisconsin plants is manufactured using PFAS; however, Ahlstrom-Munksjö is transitioning all Wisconsin facilities to FluoroFree® technology and 100 percent PFAS-free products, with a goal to eliminate PFAS use by end of 2023.

Ahlstrom-Munksjö stated the company also operates five additional pulp, paper, or paperboard manufacturing facilities in other states. Of these five facilities, only one site, in Windsor Locks, Connecticut is using significant volumes of FDA-approved PFAS. Ahlstrom-Munksjö did not provide additional information on PFAS use at the Windsor Locks, Connecticut facility or other facilities in the United States (Ahlstrom-Munksjö, 2021; EPA, 2021g).

References

Bugsel 2022

Analytical and Bioanalytical Chemistry (2022) 414:1217–1225

https://doi.org/10.1007/s00216-021-03463-9

https://www.researchgate.net/publication/353110368_LC-HRMS_screening_of_per-_and_polyfluorinated_alkyl_substances_PFAS_in_impregnated_paper_samples_and_contaminated_soils

https://link.springer.com/content/pdf/10.1007/s00216-021-03463-9.pdf

Bugsel 2023

Photocatalytical transformation of fluorotelomer- and perfluorosulfonamide-based PFAS on mineral surfaces and soils in aqueous suspensions

Science of The Total Environment Volume 894, 10 October 2023, 164907

DOI: 10.1016/j.scitotenv.2023.164907

https://www.sciencedirect.com/science/article/pii/S0048969723035301

Langberg 2021

Paper product production identified as the main source of per- and polyfluoroalkyl substances (PFAS) in a Norwegian lake: Source and historic emission tracking

Environmental Pollution 273 (2021) 116259

https://doi.org/10.1016/j.envpol.2020.116259

https://www.sciencedirect.com/science/article/pii/S0269749120369487

Lee & Mabury 2011

A pilot survey of legacy and current commercial fluorinated chemicals in human sera from United States donors in 2009.

Environ Sci Technol. 2011;45(19):8067–74

https://doi.org/10.1021/es200167q

Trier 2017

PFAS for Paper and Board for Food Contact

TemaNord 2017:573

Nordic Council of Ministers

https://doi.org/10.1007/s11356-010-0439-3

https://doi.org/10.6027/TN2017-573

Wang 2011

6:2 fluorotelomer sulfonate aerobic biotransformation in activated sludge of waste water treatment plants.

Chemosphere 82 (6), 853–858.

https://doi.org/10.1016/j.chemosphere.2010.11.003.

Washington 2015

Decades-Scale Degradation of Commercial, Side-Chain, Fluorotelomer-Based Polymers in Soils and Water.

Environ. Sci. Technol. 2015, 49, 915−923

https://achs-prod.acs.org/doi/10.1021/es504347u