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INTRODUCTION TO PFASNovember 8, 2019

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PFAS in the News https://pfasproject.com

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• PFAS Naming Conventions

• Physical/Chemical Properties of PFAS

• Sources of PFAS and Potentially-affected Sites

• Replacement PFAS Chemistry

• AFFF

• Toxicology

Today’s Topics

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PFAS Naming Conventions

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Acronyms

• PFC = Per-fluorinated chemical

• PFAS = Per- and Poly-fluoroalkyl substances

Perfluoroalkyl Substances• PFAA = Perfluoroalkyl acids

• PFOA = Perfluorooctanoic acid (perfluorooctanoate)

• PFOS = Perfluorooctane sulfonic acid (perfluorooctanesulfonate)

• PFCA = Perfluorocarboxylic acids

• PFSA = Perfluorosulfonic acids

PFCA

PFSA

PFAA

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PFCs: Do not use this acronym anymore!

• PFCs previously used to describe greenhouse gases

• PFCs do not include polyfluorinated compounds

Perfluorinated Compounds (PFCs)

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Quick Chemistry Lesson #1• Remember: PFAS are Per and Polyfluoroalkyl substances

C

FFF

F F

CC

F F

F

CC

F

F F

F

CC

F

F F

CSO3H

FF

(PFOS) SO3H = Head

PFAAs

• Perfluoroalkane sulfonates (or sulfonic acids): PFSAs

• Perfluoroalkane carboxylates (or carboxylic acids): PFCAs• Per-fluoroalkyl substances: fully fluorinated alkyl tail

O

OHC

F F

F F

FF

F F

FF

F F

(PFOA)F

FF C

CC

CC

CC

COOH = Head

Alkyl tail, fully fluorinated

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Quick Chemistry Lesson #2• Remember: PFAS are Per and Polyfluoroalkyl substances

• Poly-fluoroalkyl substances: non-fluorine atom (typically hydrogen or oxygen) attached to at least one carbon atom in the alkane chain

Fluorotelomer Alcohol (8:2 FTOH)

CF

F F

CC

F F

F

CC

F

F F

F

CC

F

F F

C

FF

F F

CC

Non-fluorine atom on one or more carbons.

OH

H H

H H

Polyfluoroalkyl substances may also be degraded to perfluoroalkyl substances (e.g., PFOS or PFOA): PRECURSORS

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• Remember: PFAS are Per and Polyfluoroalkyl substances

• Per-fluoroalkyl substances: fully fluorinated alkyl tail

• Poly-fluoroalkyl substances: partially fluorinated alkyl tail‒ Fluorotelomers

Nomenclature

Polyfluoroalkyl substances can also be precursors.

Acronym Compound Name Carbon Chain Length

PFOA Perfluorooctanoic acid C8PFOS Perfluorooctanesulfonic acid C8PFBA Perfluorobutanoic acid C4PFBS Perfluorobutane sulfonic acid C4

PFHxA Perfluorohexanoic acid C6PFHxS Perfluorohexane sulfonic acid C6

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Summary of PFAS Families

PFAS

Non-polymer PolymerPotential Precursors

Perfluorinated PolyfluorinatedPrecursors

PFAAsPFCAsPFSAs

FASAs

FTSAsFTCAsFTOHsFASEs

FASAAs

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What is a Precursor?

• Polyfluoroalkyl substances transformed to PFAAs

• Transformation

• Precursors are a concern

• 1000s of these

FTSAs: Stable under anoxic conditions Likely degrade to PFCAs in

aerobic surface waters

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• FOSE: raw material in ECF process

• FOSAA: degradation intermediate

• Can biotransform into PFCAs and PFSAs

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PFAS Families

PFCA

PFSA

PFAA

• Directly released to environment

• Produced by precursor degradation

Fluorotelomer-based Substances

FTOH FTSA FTCA

• From telomerization process

• Can biotransform into PFCAs

• FTOH far more volatile

FOSE

FOSAA

ECF-based Substances

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Polyfluorinated Substances Producing PFAAs

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PFOS: Linear and Branched Isomers

3M AFFF: Branched and linear isomers (30:70)If exclude branched isomers, concentrations underestimated and biased low.

Branched Isomers

Linear Isomers

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PFOS: Linear and Branched Isomers

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PFOA: Branched and Linear Isomers: Lab Quantitation

Correct integration of PFOA Incorrect integration of PFOA

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Long Chain Versus Short ChainWhy does it matter?• Short chain:

– PFCAs with seven or fewer carbons– PFSAs with five carbons or less

Perfluorohexanoic acid (PFHxA) is short chain PFCA.

Short-chain PFCAs Long-chain PFCAs

PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA PFUnA PFDoA

PFBS PFPeS PFHxS PFHpS PFOS PFNS PFDS PFUnS PFDoS

Short-chain PFSAs Long-chain PFSAs

• Long chain: – PFCAs with 8 or more carbons– PFSAs with six or more carbons

Perfluorohexane sulfonic acid (PFHxS) is long chain PFSA.

Source: March 2018 ITRC Factsheet

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What Are PFAS?• Poly- and per-fluoroalkyl substances

─ Generic family of chemicals─ Manmade and do not occur naturally─ Used since 1940 (Critical for the Manhattan Project)─ Can be branched or linear─ Used to make products that resist heat, oils, grease, stains, and water

• Most prevalent and researched: PFOA and PFOS• PFAS: Acid or anion?PFOS is present in the environment in the anionic form: perfluorooctane sulfonate.

Perfluorobutanoic acid Perfluorobutanoate (+ dissociated proton)

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CAS Numbers and PFAS State

PFAS State Structure CAS No.

PFOAAnion Perfluorooctanoate C7F15CO2

- 45285-51-6

Acid Perfluorooctanoic acid C7F15COOH 335-67-1

PFOSAnion Perfluorooctane sulfonate C8F17SO3

- 45298-90-6

Acid Perfluorooctane sulfonic acid C8F17SO3H 1763-23-1

Why is this important?

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Chemical Properties of Perfluoroalkyl Substances

• C-F: Strong bond

• Chemically and thermally stable

• Water soluble and mobile in groundwater

• Surfactant properties

• Recalcitrant in environment

A PFAS Micelle

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Properties: Acid vs Cation vs Anion Form

PROPERTY• Physical description• Molecular weight• Solubility in water• Vapor Pressure• Henry’s Law constant• Kow• pKa• Half-life• BCF and/or BAF

AVAILABILITY• White powder or waxy substance• Known• Known for acid and cation; N/A for Anion• Known for acid; N/A for anion and cation (*)• Estimated for acid; N/A for anion and cation (*)• Typically see values for acid form• Generally not available (some modeled values available)• Known for anion; N/A for acid & cation

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Sources of PFAS and Potentially Affected Sites

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Where Are PFAS Used?

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What Types of Sites Can Be Sources of PFAS?• Fire training facilities• Fire stations• Refineries• DoD sites/Military bases• Commercial and private airports• Landfills (leaching from consumer products)• Biosolids land application • Rail yards• Chemical facilities• Plating facilities• Textile/carpet manufacturers• Residential areas with septic systems

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Timeline of PFAS

2002

• PFOS manufacturing phased out

2006

• PFOA phased out• EPA PFOA

Stewardship Program

2009

• Stockholm Convention classifies PFOS as POP

2013-2015

• PFOA phase-out complete

• Sampling of public drinking water wells for PFAAs (UCMR3)

2016

• EPA Health Advisory announced for PFOA/PFOS (70 ppt)

1938

• PTFE discovered

1949

• PTFE used inproducts

1956

• Stain-resistant products (PFOS)

1968

• Navy developed AFFF

1978

• Detected in blood of manufacturing workers

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Global Manufacture and Use of PFAS

PFAS Manufactured Globally

PFOA & PFOS No Longer

Produced: US, Europe, Japan

Class B AFFF with PFAS Banned:

South Australia

Prohibits Import, Manufacture,

Use & Sale of PFOS/PFOA: Canada

Banned Sale, Use and Import

of PFOA: European Union

Restrict Manufacture, Import, Export, and Use of

PFOS: JapanIncreased

Production of PFOA:

China, India, RussiaEtFOSA Produced on

Industrial Scale: Brazil

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Replacement Chemistry• GenX replaces PFOA

• ADONA replaces PFOA

• 6:2 Fluorotelomers replace PFOS in metals plating

• Telomers replace PFOS and PFHxS in AFFF

• Shorter chain PFAAs replace PFOA: PFBA, PFPeA

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Four New PFAS in Revised EPA 537 Method

Analyte Acronym CAS Number

Hexafluoropropylene oxide dimer acid HFPO-DA 13252-13-6

11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid 11Cl-PF3OUdS 763051-92-9

9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid * 9Cl-PF3ONS 756426-58-1

4,8-dioxa-3H-perfluorononanoic acid * ADONA 919005-14-4

*F53B compounds

All new compounds have an oxygen molecule in the carbon chain.

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• Perfluoroether carboxylate surfactant

• Dupont/Chemours

• Is not Gen-X– one component of the Gen-X processing aid technology– is a Gen-X chemical

• Shorter-chain PFAS: 6 carbons; 5 fluorinated

• Replacement for PFOA as a surfactant and polymerization aid in production of PTFE product

Hexafluoropropylene oxide dimer acid (HFPO-DA)

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ADONA

• Polyfluoroethercarboxylate surfactant

• 3M/Dyneon

• Shorter-chain PFAS (7 carbons; 6 are fluorinated)

• Replacement for PFOA as a polymerization aid in production of PTFE product

ADONA

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F-53B

9Cl-PF3ONSF-53B: major component

11Cl-PF3OUdSF53B: minor component

• Chlorinated polyfluorinated ether sulfonate• Used in metal plating as alternatives to PFOS for mist suppression• F-53 salts likely derived from fluorotelomer raw material• Used as mist suppressant in chrome plating industry for over 30 years in China• F-53 vs F-53B

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Aqueous Film Forming Foam (AFFF)

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• Highly effective fire-fighting foam• Used for hydrocarbon fuel fires• AFFF acts as:

– An aqueous foam: primary fire extinguishing agent– An aqueous film former: a fuel vapor suppressor

What is AFFF?

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• Airports (military/domestic)

• Petrochemical Facilities

• Municipal Fire Dept.

• Industrial Fixed Systems

• Military / Government

• Marine – Off Shore Fire Protection

• Where:– Historical Use (where used to fight a fire)

– Fire Training Areas– Nozzle Testing Areas– Storage Areas

Where is AFFF Used?

Types of Fluorine-Based AFFF

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PFOS based (80%) Telomer based (20%) Developed in 1960s Production ended in 2002 Inventory remains in many

locations Contain or breakdown to

PFOS & PFHxS and possibly PFOA

Legacy 1st

Generation AFFF

Sold from 1970s - 2016 Telomers PFOR compounds (R=

cationic and anionic heads) “precursors”

PFOR – transformation to sulfonates and carboxylates

Long-chain fluorotelomers(8:2 FTS) can breakdown to PFOA

2nd Generation Fluorotelomer & Precursors AFFF

Most foam mfrstransitioned to this

No PFOS and no breakdown to PFOS

Short-chain fluorotelomers(6:2 and 4:2 FTS)

May contain trace amts of PFOA and PFOA precursors

Considered lower in toxicity and reduced BAP

Modern Fluorotelomer

AFFF

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Fluorine-Free Foams

• Alternative to AFFF in some applications• Being used at some airports and

industrial facilities in Europe, Australia, and other countries

• Do not contain PFAS or other persistent chemicals

• Contain hydrocarbon surfactants, solvents, and stabilizers

Fluorine-Free Foams available since early 1900s

Fluorine Free Foam - MSDS

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PFAS Toxicology & Risk Assessment

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Ingestion of: contaminated drinking water contaminated food (landfarming, homegrown produce) fish/wildlife (biomagnification concerns)

Contact with other impacted media (air, soil, sediment)

Use of consumer products containing PFAS – generally low ScotchguardTM treated fabrics/carpets GoreTex®

Non-stick cookware AFFF Personal care products – shampoos, dental products

Routes of Human Exposure to PFAS

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Human half-life 2-10 years (up to 70 years for complete removal) Have a low affinity for lipids and preferentially bind to proteins Cross the placental barrier and are excreted into breast milk

Toxicokinetics of PFAS

Easily absorbed, slowly metabolized, widely distributed

Stored in liver, blood, kidney, and

muscle

Reabsorbed in kidney /

transported to bileSlowly excreted

in urine and feces

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Diverse Health Effects

Developmental delays

Liver toxicity

Immune system changes

Increased cholesterol

Pregnancy-induced hypertension

Kidney and testicular cancer

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Uncertain ToxicityEstimated safe level is low for PFOA/PFOS 20 ng/kg-day, based on 2016 EPA Office of Water evaluation

‒ 10 times more toxic than arsenic

‒ Target is the developing fetus and newborn

‒ Cancer endpoints occur at higher doses than non-cancer endpoints

Safe level is unknown for most PFAS Toxicity studies are continuing, but….

‒ Difficult due to the number and variety of PFAS

‒ Responses differ between animals and humans

‒ No formal IRIS evaluation is scheduled

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July 2018 – ATSDR reviewed toxicity of 14 PFAS; published Draft Subchronic MRLs for 4 PFAS (PFOA, PFOS, PFHxS, PFNA)

• Awaiting final report

Nov 2018 – EPA released draft toxicity assessments for Gen-X chemicals and PFBS

• Comment period closed Jan 22, 2019• Final values will replace PPRTVs for PFBS

Dec 2018 – EPA announced 5 additional PFAS (PFNA, PFBA, PFHxA, PFHxS, PFDA) will be reviewed for toxicity as part of IRIS Program

• Public Comment Drafts anticipated 2020

Ongoing National Initiatives

42MRL = Minimal Risk Level

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Feb 2019 – EPA published PFAS Action Plan outlining concrete steps to address PFAS and protect public health

• Moving forward to develop MCLs for PFOA/PFOS

April 2019 – CDC/ATSDR announced intent to conduct multi-site study on human health affects associate with PFAS exposure

• Soliciting research applications from 6 communities

• Pease Health Study 2018 protocols to be used and all results will be integrated

Ongoing National Initiatives continued

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Plug for ITRC PFAS Team• Includes >350 members: industry, academia, DOD,

regulatory, consulting, analytical labs and vendors

• Seven PFAS Fact Sheets:– AFFF Introduction– History and Use– Naming Conventions and Chemical Properties – Regulations and Guidance– Fate and Transport – Site Characterization, Sampling, Lab Methods– Remediation Technologies and Methods

• 2019 – Technical Guidance Document

Questions?Elizabeth Denly, ASQ CMQ/OEP: (978) 656-3577 | E: EDenly@.TRCcompanies.comwww.TRCcompanies.com