Perfluorinated Compounds (PFCs) in the Arctic Environment: Sources, - - PowerPoint PPT Presentation

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Perfluorinated Compounds (PFCs) in the Arctic Environment: Sources, - - PowerPoint PPT Presentation

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Perfluorinated Compounds (PFCs) in the Arctic Environment: Sources, Transport and Health Concerns for Fish, Wildlife and People Alaska Community Action on Toxics April 24, 2013 1 Presentation Outline 1) Commercial sources of PFAS What

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Perfluorinated Compounds (PFCs) in the Arctic Environment: Sources, Transport and Health Concerns for Fish, Wildlife and People

Alaska Community Action on Toxics April 24, 2013

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Presentation Outline

1) Commercial sources of PFAS

– What are they used for? What chemicals are used? Importance of volatile precursors – What products are they found in? – Changes in production of PFCs chemicals (3M production ban in year 2000)

2) Why do PFCs accumulate in the Arctic?

– Transport pathways: atmospheric & oceanic – Atmospheric degradation of volatile precursors

3) PFC trends in arctic wildlife & humans

– Which PFCs accumulate in wildlife & humans? Chemicals that accumulate are NOT what is used in commercial products – Temporal trends: changes since the 3M ban – Potential health risks

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Early Scientific Interest

  • In 2001, two monitoring studies drew attention to the global

contamination of PFCs

Giesy & Kannan, ES&T, 2001, 35, 1339-1342 Hansen et al., ES&T, 2001, 35, 766-770

Figure

PFOS PFOA PFHxS Concentration (ng/ml)

10 20 30 40 50

Human Serum – United States

C F F F F F F F F F F F F F F F O O-

Perfluorooctanoate (PFOA)

F F F F F F F F F F F F F F F S O O O- F F

Perfluorooctane Sulfonate (PFOS)

Wildlife (PFOS only)

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Perfluorinated Alkyl Compounds

  • Physical-chemical properties suggest that PFOS and PFCAs (carboxylates)

should not undergo long-range transport in the atmosphere

  • How to explain contamination in remote environments, particularly top

predators? How do they get into humans?

  • Perfluorinated Sulfonates (e.g. PFOS)

– Primarily only the eight carbon molecule (PFOS) – Exclusively made by the 3M company – Production starting in the 1950s

  • Perfluorinated Carboxylates (PFCAs)

– Various chain-lengths – C8 molecule (PFOA) received considerable attention – Several companies, including Dupont – Production starting in the 1970s – Fluorotelomer-manufacturing process

C F F F F F F F F F F F F F F F O O-

Perfluorooctanoate (PFOA)

F F F F F F F F F F F F F F F S O O O- F F

Perfluorooctane Sulfonate (PFOS) 4

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Regulatory Interest

  • Production of PFOS related chemicals was banned by 3M in 2000 due to

presence in humans and the environment

  • PFOS placed on the Stockholm Convention in May 2009 (Annex B)
  • Canada banned the import of 4 fluorotelomer-based polymers that have the

potential to degrade to bioaccumulative PFCAs (June 2006)

  • US EPA initiated the 2010/2015 PFOA Stewardship Program, phase out of

long-chain PFCAs by 2015

– Commitments by the 8 major manufacturers (Arkema, Asahi, BASF, Clarient, Daikin, 3M, DuPont, Solvay Solexis) – Includes PFCAs and precursor chemicals

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Commercial Sources of PFCs

  • Poly- and Perfluorinated Compounds (PFCs) are widely used in

commercial products

  • Resists water (hydrophobic) and oil (oleophobic) and thus are used

primarily for their unique stain repellency properties

  • Specific uses include:

1. surface treatment protection (carpets, textiles, leather) 80% 2. paper protection (food paper packaging) 20% 3. “performance chemicals” (firefighting foams, floor waxes, coatings, electroplating and etching baths, chemical intermediates) trace

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PFC Uses

  • Products containing poly- and perfluorinated compounds

are widespread and uses are growing

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Introduction: NOT Teflon!

  • Teflon is a fluoropolymer made of polytetrafluoroethylene (PTFE)
  • Manufactured by Dupont
  • Main commercial application is non-stick pans
  • Very low coefficient of friction, very non-reactive
  • PFOA is used a polymerization aid, but not detected in final products
  • TEFLON PANS ARE NOT A SOURCE OF PFOA!

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PFAS Uses

  • Fluorinated Polymers (80%)

– Reduce the coefficient of friction for materials – High Molecular weight polymer, contains fluorinated monomer – Commercial Products: Stain repellents for carpets, textiles, leather (Scotchgard, Teflon Advanced)

O O F F F F F F F F F F F F F F F F F O O F F F F F F F F F F F F F F F F F R O O R O O

O O F F F F F F F F F F F F F F F F F

What happens to unreacted monomer?

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PFAS Uses

  • Fluorinated Surfactants (20%)

– Reduce the surface tension of surfaces and liquid – Chemicals: Polyfluorinated Phosphates (PAPs) and Perfluorinated Sulfonates (PFOS) – Commercial Products: Fire Fighting Foams, Stain Repellents for Paper, Leveling Agents for Floor Waxes, Cosmetics

P O HO OH O CF3(CF2)x P O O OH O CF3(CF2)x CF3(CF2)x

Mono-PAPs Di-PAPs

F F F F F F F F F F F F F F F S O O O- F F

Perfluorooctane Sulfonate (PFOS)

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Fluorotelomer Production

Volatile “precursors”

  • bserved in the

atmosphere

Sales Products (Fluoropolymers)

Ethane “spacer”, susceptible to degradation

CF2=CF2 F(CF2CF2)nI F(CF2CF2)nCH2CH2I F(CF2CF2)nCH2CH2OH F(CF2CF2)nCH2CH2OC(O)CH=CH2 F(CF2CF2)nCH=CH2 TFE Telomer A Fluorotelomer Iodide (FTI) Fluorotelomer Alcohol (FTOH) Fluorotelomer Acrylate Monomer (FTAc) Fluorotelomer Olefin (FTO) F(CF2CF2)nCH2CH2OP(O)OH2 Fluorotelomer Phosphates (PAPs) Various Chain Lengths (e.g. 6:2, 8:2, 10:2) 11

  • Made by Dupont & others (Asahi, BASF, Clariant,

Daikin, Solvay Solexis) from 1970s-present

  • Telomer-based chemicals, many different sizes

(8:2 was most common)

  • Degrade to PFOA and other chain-length PFCAs
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Perfluorooctane Sulfonyl Fluoride (POSF) Compounds (3M)

Observed in the Atmosphere

C8F17 S O O F C8F17 S O O OH

POSF PFOS

C8F17 S O O NH C8F17 S O O NH C8F17 S O O N OH

N-MeFOSA N-EtFOSA N-MeFOSE N-EtFOSE

C8F17 S O O N OH

Intermediates for surfactants, phosphates and polymers Sulfonamides and Sulfonamide alcohols

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  • Made by the 3M company from 1950-2002
  • Sulfonamide chemicals, only 8 carbons
  • Degrade to PFOS during metabolism;

degrade to PFOA & PFOS in the atmosphere

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How do PFCs get into the environment?

commercial products direct release to air, water volatile precursors FT phosphates food, dust ingestion PFCAs atmospheric & biological degradation PFCAs (e.g. PFOA), PFSAs (PFOS) river & ocean contamination PFCAs (e.g. PFOA), PFSAs (PFOS)

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Atmospheric Degradation: Formation of PFCAs and PFOS

Fluorotelomer Acrylate Fluorotelomer Alcohol Fluorotelomer Iodide Fluorotelomer Olefins

Fluorotelomer Aldehyde Perfluorinated Aldehyde Perfluorinated Carboxylates 14 Sulfonamide Alcohol Sulfonamide

PFOS PFOA

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Volatile precursors are found in the atmosphere

Source: Shoeib et al., Environ. Sci. Technol. 2006, 40, 7577-7583

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Precursors & PFCAs in Waterproof Clothing

Source: Greenpeace, “Chemistry for any weather”, 2012 20 40 60 80 100 Percent Composition PFCAs FTOHs & FTACs

North Face

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Transport Pathways to the Arctic

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PFCAs & PFOS are detected in the ocean PFCAs & PFOS precursors are detected in the atmosphere

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Biological Transformation

  • Perfluorinated carboxylates (PFCAs) and sulfonates (PFSAs) are NOT

susceptible to biological transformation (metabolism)

  • However, polyfluorinated compounds (e.g. alcohols, acrylates) can undergo
  • xidative metabolism to eventually yield PFCAs and PFSAs

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Fluorotelomer Acrylate Fluorotelomer Alcohol FT Phosphate Surfactant

Perfluorinated Carboxylates Sulfonamide Alcohol Sulfonamide

PFOS

ECF Phosphate Surfactant

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Fluorinated Phosphate Surfactants

  • Fluorinated phosphate (ester) surfactants are added to food packaging

paper to resist oil and water

  • Most well-known application is microwave popcorn bags, but they are

widely used and detected!

  • The fluorinated “tail” may be either telomer- or sulfonamide-based (formally

produced by the 3M company)

  • Fluorotelomer PAPS have been shown to degrade to PFCAs in rat studies

FT monoPAPs SN-diPAPs FT diPAPs

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Human Blood: PFCs widely detected

  • Detected in human blood from North America, South America, Europe, Asia,

Africa and Australia

  • Levels of PFOS are decreasing since early 2000s, coinciding with the 3M

production ban

PFOS PFOA (C8) PFNA (C9) PFDA (C10)

Source: Haug et al., Environ. Sci. Technol. 2009

PFCs in Human Blood from Norway

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Human Blood: Arctic regions

  • Only two studies from arctic regions, both from Nunavik (Northern Quebec)
  • PFOS in adults (19 ng/ml) was comparable to those in more southern

regions (Dallaire, Environ. Sci. Technol., 2009, 43, 5130-5136)

  • Children had lower PFOS levels (3.4 ng/ml) as compared to adults (O’Brien,
  • Environ. Sci. Technol., 2012, 46, 4614-4623)
  • Impact on thyroid hormones: Higher PFOS levels associated with lower

TSH, total T3 and TBG but higher free T4 (Dallaire, EHP, 2009, 117, 1380-1386)

  • Impact on plasma lipid levels: Higher PFOS levels associated with lower

triglycerides and total cholesterol:HDL-C ratios, but higher levels of HDL-C

(Chateau-Degat, Environ. Int., 2012, 110, 710-717) 21

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PFCs in ringed seals from the Canadian Arctic

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Source: Butt et al., Environ. Toxicol. Chem. 2008, 27, 542-553

PFOS dominates, PFOA usually not detected in arctic wildlife but longer-chain PFCAs detected

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Wildlife: Biomagnification in Marine Food Webs

  • Several studies on marine food webs from eastern & western Canada and

Norway

  • Increasing PFOS levels with trophic level, suggesting biomagnification

PFOS concentrations vs. tropic level for an eastern Canadian Arctic food web. BLKI = black- legged kittiwakes GLCU = glaucous gulls. Source: Tomy et al., 2004

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Polar bears have the highest PFC levels measured in wildlife

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Arctic Wildlife Levels Lower than Temperate/Sub-Tropical

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concentration (ng/g ww)

200 400 600 800 1000 1200 temperate/sub-tropical arctic/antarctic arctic temperate/sub-tropical

PFOS concentrations (ng/g ww) in seals & sea otters from arctic and temperate/sub-tropical regions. Data represents mean, median

  • r individual values in blood or liver.

Similar geographic trends for whales and birds

Source: Butt, unpublished

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Health Concerns for Wildlife

  • No known (observed) health effects of PFCs in arctic wildlife
  • PFCs accumulate in the liver, potential for liver toxicity
  • Recent study shows that PFCs can cross the blood-brain barrier in polar

bears; potential for neurotoxicity (Greaves et al., 2013, Environ Toxicol. Chem. 2013, 32, 713-722)

  • Laboratory studies show PFC exposure associated with

immunosuppression, neurotoxicity and thyroid hormone alteration

  • Recent fish study showed that embryos exposed to PFOS had liver damage

and immune system suppression as larvae

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PFCs in biological environment: Knowledge Gaps

  • The marine food web is very well studied; many studies from the Canadian

Arctic and Greenland

  • Ringed seals and polar bears are the best studied
  • Much less is known about terrestrial and freshwater food webs
  • Very few reports on PFCs in fish
  • Evidence for biomagnification in a lichen-wolf-caribou food web

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PFOS-Precursor Production: 3M Ban

Year

1970 1975 1980 1985 1990 1995 2000 2005

POSF Production Volume (tonnes)

1000 2000 3000 4000 5000

Smithwick et al. Prevedouros et al. 3M Global Production (Paul et al.) Total Global Production (Paul et al.)

Source: Paul et al., 2009

* POSF-compounds degrade to PFOS via atmospheric oxidation and biotransformation

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Canadian Arctic Ringed Seals - PFOS

  • Levels of perfluorinated stain repellent (PFOS) are declining in ringed seals

from the Canadian Arctic, in response to the voluntary ban in production by the major manufacturer (3M)

  • Transport of volatile precursors in the major transport pathway to remote

environments

Arviat, Nunavut

Year

1992 1995 1998 2001 2004 2007 2010

PFOS Concentration (ng/g ww) 20 40 60 80 100 120 140

Resolute Bay, Nunavut

Year

1970 1975 1980 1985 1990 1995 2000 2005 2010

5 10 15 20 25 30 35

28 Source: Butt et al. Environ. Sci. Technol. 2007, 41, 41-49 and unpublished updated data

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Sea Otters from southern Alaska

29 Source: Hart et al., Arch. Environ. Contam. Toxicol. 2009, 56, 607-614

PFOS decline from 1998-2001 -> 2002-2007

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Seabirds from Prince Leopold Island, Nunavut

30 Source: Braune & Letcher, Environ. Sci. Technol. 2013, 47, 616-624

ΣPFCAs increasing, PFOS steady from 1975-2010

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Ringed Seals from Greenland

31 Source: Butt et al., Sci. Total Environ., 2010, 408, 2936-2965

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Shifts in Production: Smaller Chemicals

  • 3M shifted production to 4-carbon chemicals (PFBS)
  • US EPA PFOA Stewardship Program: Fluorotelomer manufacturers

shifted to 6:2-based chemistry (formation of PFHxA and smaller PFCAs)

  • Smaller chemicals are less bioaccumulative, very few detections of

PFBS in arctic wildlife

  • Toxicity not well understood; likely similar effects but lower toxicity

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PFCs in the Arctic - Recap

  • Chemicals that accumulate in wildlife and humans are NOT what is

commercially used

  • Industrial synthesis of fluorinated polymers (80%) of commercial market

produces several volatile, reactive chemicals that degrade (biologically or atmospherically) to PFCAs and PFOS

  • Atmospheric half-life of these volatile precursors sufficient to allow for

transport to remote environments

  • Commercial market changed drastically in 2001

F F F F F F F F F F F F F F F S O O O- F F

Perfluorooctane Sulfonate (PFOS) 33

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PFCs in the Arctic - Recap

  • PFCs are widely detected in the humans and wildlife
  • The arctic environment is the most-studied region for PFCs
  • PFCs biomagnify in the food web; polar bears have the highest

concentrations of any wildlife or humans

  • Temporal trends indicate PFOS levels declining, PFCA levels

increasing; trends are variable in different regions

  • Replacement chemicals?
  • Unclear if PFCs are causing harmful effects in wildlife

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