Are Per- and Polyfluoroalkyl Substances a Vapor Intrusion

Concern?Julia Roth

Environmental Engineer

Topics Discussed:• Background

• What are Per- and Polyfluoroalkyl Substances (PFAS)?• PFAS Classification

• PFAS Volatility• Theoretical Henry’s Law Constants and Vapor Pressures• Particle – Gas Partitioning • Indoor Air Background Sources

• AFFF Volatility Box Experiment

Background

What are Per- and Polyfluoroalkyl Substances (PFAS)?

(Parsons et. al., 2008)

(National Academies of Sciences, Engineering, and Medicine, 2017)

(PFHA)

(8-2 FTOH)

(PFOA)

(National Academies of Sciences, Engineering, and Medicine, 2017)

PFAS ClassificationPFAS Precursor Families:

• FASAs: Perfluoroalkyl Sulfamido Substances

• FTOHs: Fluorotelomer Alcohols

• FTSs: Fluorotelomer Sulfonic Acids

PFAS Production Methods:• ECF: Electrochemical

Fluorination • FT: Telomerization

PFAS Volatility

Theoretical Henry’s Law Constants and Vapor Pressures

Meets USEPA’s 2015 volatility criteria:1) Henry’s Law Constant > 10-5 atm*m3/mol

SubstanceAqueous Solubility

(g/L)

Pvapor

(PA)

Henry's Law Constant

(atm m3 mol-1)

PFOS (K+) 5.19 E-1 3.31 E-4 3.4 E-9

PFOA (H+) 9.5 7.0 E1 4.6 E-6

PFOA (NH4+) >5.00 E2 <1.3 E-3/9.2 E-3 <1.1 E-11/7.8 E-11

N-EtFOSE 1.51 E-4 5.4 E-1 1.9 E-2

N-EtFOSEA 8.9 E-4 N.A. --

6:2 FTOH 1.2-1.7 E-2 N.A. 1 E -2

8:2 FTOH 1.40 E-4 2.93 9.6 E-2

Source: Hekster et al (2002)

Particle – Gas Partitioning 6:2 FTOH 8:2 FTOH 10:2 FTOH MeFOSE EtFOSE

Arctic Gas Phase Air Concentration

Arith

met

ic M

eans

(pg/

m3) 2.65 11.4 6.57 8.3 1.87

Arctic Particle Phase Air

ConcentrationBDL 3.5 0.8 3.53 1.05

Toronto Gas Phase Air Concentration 17.7 40.2 21.2 8 2.33

Toronto Particle Phase Air

Concentration0.31 0.71 1.09 4.2 0.96

Arctic Particle Phase

Perc

enta

ge BDL 23% 15% 32% 22%

Toronto Particle Phase BDL 2% ± 1% 5% ± 3% 30% ± 16% 30% ± 16%

Notes: 1) BDL = Below Detection Levels2)MeFOSEA was analyzed for, but below detection levelsSource: Shoeib et al (2006)

Key Takeaway:• All PFAS precursors

analyzed were vapor phase dominant

VaporParticle

8:2 FTOH

Arctic Cruise

Toronto

http://time.com/3843376/chemical-pfas-products/

https://chemicalwatch.com/64234/california-publishes-evidence-for-restricting-carpets-containing-pfass

Indoor Air Background Sources • Non-Stick Cookware• Food Packaging/Cardboard

Products• Water-resistant clothing• Carpet• Sunscreen• Takeout Containers• Paint• Shampoo• Sunscreen• Pesticides

https://www.denix.osd.mil/army-pfas/home/

(Winkens et al, 2017)(Yao et al, 2018)

(Lang et al, 2016)

AFFF Volatility Box Experiments

Project Team

David Hanigan, PhDUtsav Thapa, PhD

David Wevill, PhD, MRSCWade Bontempo

Nicola Watson, PhDChris Heron

Martha Maier

Julia RothTiffany Hill

James HattonChris Lutes

Bill DiguiseppiChase Holton, PhD, now at Geosyntec

Experimental Setup Experimental Parameters

Flow Rate (cc/min) 200

Dilution 50% AFFF; ~2.5% active ingredient

AFFF Expansion Ratio 15:1

Sample Duration (hours) 24

Sample Breakdown

Sample Type XAD/PUF Samples TD Samples

No. of equipment blanks 1 1

No. of samples 2 2

No. of duplicate samples 1 1

Analytical Method: LC-MS-MS (MRM)Liquid Chromatography–Mass Spectrometry Multiple Reaction Monitoring• XAD/PUF Sampling with LC-MS-MS has been

developed for 30 PFAS • PFBA ,PFPeA , PFBS , 4:2 FTS , PFHxA , PFPeS, PFHpA , PFHxS, 6:2 FTS,

PFOA, PFHpS , PFNA, PFOSA, PFOS, PFDA, 8:2 FTS, PFNS, MeFOSAA, EtFOSAA, PFUnA, PFDS, PFDoA, MeFOSA, PFTrDA, PFTeDA, EtFOSA, PFHxDA, PFODA, MeFOSE, and EtFOSE

• Reporting limit of 2 ng/L (or ppt)

Analytical LC-MS-MS (MRM) PFAS Results

Note: 3/30 PFAS Compounds Detected with LC-MS-MS (MRM)

Compound CAS No. Equipment Blank (ng/L)

Sample 1 (ng/L)

Sample 2 (ng/L)

Sample 3 (ng/L)

PFBA 375-22-4 3.45 5.43 3.98 4.27PFHxA 307-24-4 ND 41.7 33 32.16:2 FTS 27619-97-2 ND 66.7 77.5 47.3

Key Takeaways:• PFHxA and 6:2 FTS were present in AFFF emissions, but not at

levels that would be of concern for Vapor Intrusion• PFHxA and 6:2 FTS are intermediates in the degradation pathway• PFBA may have been detected due to background

https://pubchem.ncbi.nlm.nih.gov

Analytical LC-MS-MS (MRM) PFAS Results Cont.

Note: 27/30 PFAS Compounds Not Detected with LC-LM-MS

Key Takeaways:• Based on the age of the foam it

is likely primarily C6• 6:2 FTS (an intermediate in the

degradation pathway) was present

• 8:2 FTS was not detected• 4:2 FTS was not detected

• FTOHs may be present because of the telomerization process

Compound CAS No.

PFPeA 2706-90-3PFBS 375-73-5

4:2 FTS 757124-72-4 PFPeS 2706-91-4 PFHpA 375-85-9 PFHxS 355-46-4PFOA 335-67-1 PFHpS 375-92-8 PFNA 375-95-1

PFOSA 754-91-6 PFOS 1763-23-1 PFDA 335-76-2

8:2 FTS 39108-34-4 PFNS 68259-12-1

Compound CAS No.

MeFOSAA 2355-31-9EtFOSAA 2991-50-6 PFUnA 2058-94-8 PFDS 335-77-3

PFDoA 307-55-1 MeFOSA 31506-32-8 PFTrDA 72629-94-8PFTeDA 376-06-7 1EtFOSA 4151-50-2 PFHxDA 67905-19-5 PFODA 16517-11-6

MeFOSE 24448-09-7 EtFOSE 1691-99-2

Analytical Method: TD-GC-MSThermal Desorption Gas Chromatography–Mass Spectrometry• TD Sampling with GS-MS has been developed for 22 PFAS

• PFOA , PFDoA, PFPeA , PFHxA, PFDA, PFUdA, PFTrDA, PFHpA, PFNA, PFTeDA, PFHxDA, PFODA, N-MeFOSA-M, N-EtFOSA-M, N-MEFOSE-M, N-EtFOSE-M, FBET, 5:2sFTOH, FHET, 7:2sFTOH, FOET, FDET

• Additional fluorinated and non-fluorinated tentatively identified compounds were available with this method

• Reporting limit of ~100 ng/L (or 100 ppt)Note: Due to the long sample duration, TD tubes may have been oversaturated. Shorter follow-on experiments are being performed where lower limits are expected to be achieved.

Analytical TD-GC-MS PFAS TICs Results 9 Fluorinated Compounds Tentatively Identified in All Replicates with GC/MS

Hexadecafluoroheptane335-57-9

Perfluorooctane307-34-6

Perfluoroeicosane37589-57-4

Perfluorooctanonitrile647-12-1

1H,1H,2H-Perfluoro-1-octene

25291-17-2

1H,1H,2H-Perfluoro-1-decene

21652-58-4

Perfluorohexyl iodide355-43-1

3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluoro-1-iodo-

1-octene-1150223-14-6

1H,1H,2H,2H-Perfluorooctyl iodide

2043-57-4

https://pubchem.ncbi.nlm.nih.gov

Analytical TD-GC-MS Non-PFAS TICs ResultsCompound CAS No.

2-Propanol, 2-methyl- 75-65-0Butanal 123-72-8

1-Propanol, 2-methyl- 78-83-12,4-Hexadiene 592-46-1

4-Methyl-1,3-pentadiene 926-56-71-Butanol 71-36-3

1,4-Dioxane 123-91-1n-Propyl acetate 109-60-4

2,4-Dimethylfuran 3710-43-8Butanenitrile, 2-methyl- 18936-17-9Methyl Isobutyl Ketone 108-10-1

Toluene 108-88-32-Methyl-2-butenenitrile 4403-61-63-Butenenitrile, 2-methyl- 16529-56-91,4-Dioxane, 2,5-dimethyl- 15176-21-33-Penten-2-one, 4-methyl- 141-79-7

Compound CAS No.1,4-Dioxane, 2,5-dimethyl- 15176-21-3

20-Carboethoxy-20-demethylvincadifformine 112496-64-7

1,4-Dioxane, 2,5-dimethyl- 15176-21-3Ethanol, 2-iodo- 624-76-0

Ethylbenzene 100-41-4Benzene, 1,3-dimethyl- 108-38-3

p-Xylene 106-42-3Benzene, 1,3-dimethyl- 108-38-3

o-Xylene 95-47-6Hexylene glycol 107-41-5

4-Heptanone, 2,6-dimethyl- 108-83-84-Octanone, 2-methyl- 7492-38-8

Benzaldehyde 100-52-7Benzene, 1,2,4-trimethyl- 95-63-6

Mesitylene 108-67-8Benzofuran 271-89-6

Compound CAS No.2-Hexen-1-ol, 2-ethyl- 50639-00-4

o-Cymene 527-84-4Benzene, 1-methyl-3-(1-

methylethyl)- 535-77-3

1-Octanol 111-87-5Pentanoic acid, butyl ester 591-68-4

Benzene, 1-methyl-4-propyl- 1074-55-1Cyclopentasiloxane,

decamethyl- 541-02-6

2-Butenoic acid, 2-methyl-, 2-methylpropyl ester, (E)- 61692-84-0

Benzene, 1,2,3,5-tetramethyl- 527-53-7Benzene, 1-ethyl-2,4-dimethyl- 874-41-9

Tetradecane, 4-methyl- 25117-24-2Naphthalene, 2-methyl- 91-57-6

Conclusions• The AFFF Volatility Box Experiments are the first step in

understanding PFAS vapor intrusion• PFAS Analytes detected with LC-MS-MS (MRM) are not in high

enough concentrations to be a vapor intrusion concern• AFFF feedstock impurities detected with TD-GC-MS would likely

volatilize readily after release• Two sampling and analytical methods have been developed:

• XAD/PUF Sampling with LC-MS-MS (MRM) has been developed for 30 PFAS • TD Sampling with TD-GC-MS has been developed for 22 of the PFAS

Standards

Thank you for your timeQuestions?

Julia RothJulia.Roth@Jacobs.com(508)654-8525

References1. National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of

AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. https://doi.org/10.17226/24800.

2. Parsons, John & Saez, Monica & Dolfing, Jan & De Voogt, Pim. (2008). Biodegradation of Perfluorinated Compounds. Reviews of environmental contamination and toxicology. 196. 53-71. 10.1007/978-0-387-78444-1_2.

3. Perfluorinated Chemicals in the Arctic Atmosphere M. Shoeib, T. Harner, and, and P. Vlahos, Environmental Science & Technology 2006 40 (24), 7577-7583 DOI: 10.1021/es0618999.

4. Release of Per- and Polyfluoroalkyl Substances (PFASs) from Carpet and Clothing in Model Anaerobic Landfill Reactors. Johnsie R. Lang, B. McKay Allred, Graham F. Peaslee, Jennifer A. Field, and Morton A. Barlaz. Environmental Science & Technology 2016 50 (10), 5024-5032. DOI: 10.1021/acs.est.5b06237

5. Kerstin Winkens, Jani Koponen, Jasmin Schuster, Mahiba Shoeib, Robin Vestergren, Urs Berger, Anne M. Karvonen, Juha Pekkanen, Hannu Kiviranta, Ian T. Cousins. Environmental Pollution, Volume 222, 2017, Pages 423-432, ISSN 0269-7491Perfluoroalkyl acids and their precursors in indoor air sampled in children's bedrooms.

6. Per- and Polyfluoroalkyl Substances (PFASs) in Indoor Air and Dust from Homes and Various Microenvironments in China: Implications for Human Exposure. Yiming Yao, Yangyang Zhao, Hongwen Sun, Shuai Chang, Lingyan Zhu, Alfredo C. Alder, and Kurunthachalam Kannan. Environmental Science & Technology 2018 52 (5), 3156-3166. DOI: 10.1021/acs.est.7b04971

7. Chemical Structures: https://pubchem.ncbi.nlm.nih.gov