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Per- and Polyfluoroalkyl Substances

Treatment Processes
Fate and Transport
CAS Number:
Synonyms: 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (FRD-902), 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid (FRD-903), GenX, Heptadecafluorononanoic acid, Heptafluorobutyric acid, Nonadecafluorocapric acid, Nonadecafluorodecanoic acid, Pefluorobutane sulfonate, Perfluorobutanoic acid (PFBA), Perfluorobutyl sulfonate (PFBS), Perfluorobutyric acid, Perfluorocapric acid, Perfluorodecanoic acid (PFDA), Perfluorohexanesulfonic acid potassium salt, Perfluorohexyl sulfonate (PFHxS), Perfluorononanoic acid (PFNA), Potassium tridecafluoro-1-hexanesulfonate, Tridecafluorohexane-1-sulfonic acid potassium salt, heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether (E1)
Contaminant Type: Chemical

Per- and polyfluoroalkyl substances (PFASs) are fluorinated aliphatic substances with unique properties, such as being both hydrophobic, lipophobic, and extremely stable due to the strength of the C-F bond [2539]. Their properties have led to their extensive use as surface active agents in products like stain repellants and fire-fighting foams [2527, 2539]. The two most frequently studied PFASs, perfluorooctane sulphonate (PFOS) and perfluorooctanoic acid (PFOA), have their own, separate entries in this treatability database. Both PFOS and PFOS are compounds with eight carbon atoms. This group entry covers treatability data for other PFASs, including those with more or fewer carbon atoms. It currently includes data for: 

  • Perfluorotridecanoic acid (PFTriA): Chemical Abstract Service number (CAS No.) 72629-94-8, a 13-carbon compound
  • Perfluorododecanoic acid (PFDoA): CAS No. 307-55-1, a 12-carbon compound
  • Perfluoroundecanoic acid (PFUnA): CAS No. 2058-94-8, an 11-carbon compound
  • Perfluorodecanoic acid (PFDA): CAS No. 335-76-2, a 10-carbon compound
  • Perfluorononanoic acid (PFNA): CAS No. 375-95-1, a 9-carbon compound
  • Perfluorohexanoic acid (PFHpA): CAS No. 375-85-9, a 7-carbon compound
  • Perfluorohexanoic acid (PFHxA): CAS No. 307-24-4, a 6-carbon compound
  • Perfluoropentanoic acid (PFPeA): CAS No. 2706-90-3, a 5-carbon compound
  • Perfluorobutanoic acid (PFBA): CAS No. 375-22-4, a 4-carbon compound
  • Perfluorodecyl sulfonate (PFDS): CAS No. 335-77-3, a 9-carbon compound
  • Perfluoroheptyl sulfonate (PFHpS): CAS No. 375-92-8, a 7-carbon compound
  • Perfluorohexyl sulfonate (PFHxS): CAS No. 3871-99-6, a 6-carbon compound
  • Perfluorobutyl sulfonate (PFBS): CAS No. 29420-49-3, a 4-carbon compound
  • Perfluorooctanesulfonamide (PFOSA): CAS No. 754-91-6, an 8-carbon compound
  • Fluorotelomer sulfonate 8:2 (FtS 8:2): CAS No. 39108-34-4
  • Fluorotelomer sulfonate 6:2 (FtS 6:2): CAS No. 27619-97-2
  • N-ethyl perfluorooctane sulfonamidoacetic acid (N-EtFOSAA): CAS No. 2991-50-6
  • N-methyl perfluorooctane sulfonamidoacetic acid (N-MeFOSAA): CAS No. 2355-31-9

This group also includes the 6-carbon compound GenX (CAS No. 62037-80-3 as ammonium salt; CAS No. 13252-13-6 as acid), although limited treatability data are currently available for that particular PFAS.

The U.S. manufacturer of PFOS phased out production of PFOS and PFHxS in 2002 and major companies worldwide are working to reduce product content, use, and emissions of PFOA and longer chain perfluorocarboxylic acids [2166, 2441, 2512]. These PFASs, however, are persistent and bioaccumulative [2441, 2512, 2520, 2541]. Therefore, they are expected to remain of environmental relevance for the foreseeable future [2441, 2512]. In addition, the phase out of longer chain PFASs could lead to shifts in production towards shorter chain and fluorinated PFASs [2521].

PFASs can be emitted into the air and water by industrial processes that manufacture or use fluorochemicals. PFASs can also enter groundwater and surface water through disposal of waste and sewage sludge and as a result of fire-fighting activities and training [2540]. PFASs have been detected in waters worldwide, including in surface water, groundwater, tap and bottled water, and in industrial and municipal wastewater [1705, 1756, 2164. 2166. 2441, 2512, 2520]. EPA's third Unregulated Contaminant Monitoring Rule (UCMR3) included six PFASs: PFOA, PFOS, PFNA, PFHxS, PFBS, and perfluoroheptanoic acid (PFHpA). As a result, these PFASs were detected in a small percentage of public water supplies around the country [2540, 2541]. PFAS have also been detected in human tissue, blood, and breast milk. This occurrence has been traced to food, drinking water, and/or workplace exposure [2441, 2512, 2520].

PFOS and PFOA have been shown to be associated with high cholesterol, increased liver enzymes, decreased vaccination response, thyroid disorders, pregnancy induced hypertension and preeclampsia, and cancer [2541]. Data on the toxicological effects of other PFASs are more limited. In general, however, the available data suggest the longer chain compounds are more potent and persistent in humans than shorter chain PFASs [2441, 2512]. EPA has established a drinking water health advisory of 70 nanograms per liter (ng/L) for PFOS and PFOA, both individually and combined [2541]. At this time, EPA has not established guidelines for other PFASs, but some states have begun to do so. For example, New Jersey has proposed maximum contaminant levels for PFOA and PFNA and North Carolina has set a health goal for GenX [2540].

Date of Literature Search: May 2018

1705 Loos, R., Wollgast, J., Huber, T. and Hanke, Georg; 2007; Polar herbicides, pharmaceutical products, perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and nonylphenol and its carboxylates and ethoxylates in surface and tap waters around Lake Maggiore in Northern Italy; Anal. Bioanal. Chem.; 387:1469
1756 Takagi, S., Adachi, F., Miyano, K., Koizumi, Y., Tanaka, H., Mimura, M., Watanabe, I., Tanabe, S. and Kannan, K.; 2008; Perfluorooctane sulfonate and perfluorooctanoate in raw and treated tap water from Osaka, Japan; Chemosphere; 72:1409
2164 Oscar, Q. and Snyder S; 2009; Occurrence of Perfluoroalkyl Carboxylates and Sulfonates in Drinking Water Utilities and Related Waters from the United States; Environ. Sci. Technol.; 43:24:9089
2166 McLaughlin, C., Blake, S., Hall, T., Harman, M., Kanda, R., Foster, J. and Rumsby, P.; 2011; Perfluorooctane sulphonate in raw and drinking water sources in the United Kingdom; Water and Environment Journal; 25:1:13
2441 Dickenson, Eric R.V. and Christopher Higgins; 2016; Treatment Mitigation Strategies for Poly- and Perfluoroalkyl Substances; Treatment Mitigation Strategies for Poly- and Perfluoroalkyl Substances; Water Research Foundation. Web Report #4322.
2512 Fulmer, A.; 2016; Poly- and Perfluoroalkyl Substances: Background Technical Information; Water Research Foundation; August
2520 Rahman, M., Peldszus, S., and Anderson, W.; 2014; Behaviour and fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in drinking water treatment: A review; Water Research; 50: 318-340
2521 Sun, M., Dudley, L., Arevalo, E., Strynar, M., Lindstrom, A., and Knappe, D.; 2016; Removal of traditional and emerging perfluoroalkyl substances by powdered activated carbon adsorption and anion exchange; AWWA Water Quality Technology Conference; Proceedings
2527 Zhi, Y., and Liu, J.; 2015; Adsorption of perfluoroalkyl acids by carbonaceous adsorbents: Effect of carbon surface chemistry; Environmental Pollution; 202: 168-176
2539 Buck, R. C., J. Franklin, U. Berger, J. M. Conder, I. T. Cousins, P. De Voogt, A. A. Jensen, K. Kannan, S. A. Mabury and S. P. van Leeuwen; 2011; Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins; Integrated Environmental Assessment and Management; 7(4): 513-541
2540 Knappe, D., Dickenson, E., and Hertz, C.; 2018; Per- and Polyfluoroalkyl Substances (PFAS) in Water: Background, Treatment and Utility Perspective; Water Research Foundation; WRF Webcast, May 31
2541 U.S. Environmental Protection Agency; 2016; Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA); Office of Water; EPA 822-R-16-005
2555 Crone, B.C., T.F. Speth, D.G. Wahman, S.J. Smith, G. Abulikemu, E.J. Kleiner and J.G. Pressman.; 2019; Occurrence of per- and polyfluoroalkyl substances (PFAS) in source water and their treatment in drinking water.; Critical Reviews in Environmental Science and Technology; Vol. 49, Issue 24
2556 Ross, I., J. McDonough, J. Miles, P. Storch, P.T. Kochunarayanan, E. Kalve, J. Hurst, S.S. Dasgupta, J. Burdick. ; 2018; A review of emerging technologies for remediation of PFASs.; Remediation; 29:101-126
2557 Speth, T., R. Khera, P. Ransom, N. Dugan, and C. Patterson. ; 2019; Emerging Concern (CECs): Per- and Polyfluoroalkyl Substances (PFAS), Cyanotoxins, and Perchlorate. ; Presentation delivered on February 26, 2019, as part of the EPA’s Small Systems Monthly Webinar Series. ;