1
Can a smog chamber be used to explain why polar bears have 8.6 ng/g of perfluoro
octanoic acid in their body?
Ole John NielsenDepartment of ChemistryUniversity of Copenhagen
www.cogci.dk
2
Acknowledgements
Mads P. S. AndersenJPL-NASA, Pasadena, CA, USA
Tim. J. Wallington, Mike. P. Hurley, Jim. C. BallFord Motor Company, Dearborn, MI, USA
Scott. A. MaburyUniversity of Toronto, Toronto, ON, Canada
3
Why am I here?
4
Outline
1. Who am I?2. Why the interest in PerFluoro Organic Acids
(PFOAs) and FluoroTelomer alcohols (FTOHs)?3. What are PFOA, PFCA and PFOA again?
4. Use of FTOH = CnF2n+1CH2CH2OH (straight chain)5. Atmospheric chemistry of FTOHs6. Environmental Impacts and Conclusions7. Discussions
5
Who am I?1954 Born1973 Began at UoC (chemistry and physics)1974 Important Atmospheric Year1978 M.Sc. and on to do a PhD at Risø Nat. Lab.1978-95 Risø National Laboratory1995-96 Ford Research Center Aachen, Germany1996-99 Risø National Laboratory1999-? Professor at UoC2007 Nobel Peace Prize together with Al Gore and 2500 scientists
Gas phase kinetics and reaction mechanisms - relevant to the atmosphere – How? Why?
IPCC – Intergovernmental Panel of Climate Change
6
2. Why the interest in PerFluoro Organic Acids (PFOAs) and FluoroTelomer alcohols (FTOHs)?
• What do you think?• The interest in environmental chemistry is driven by?• Health Concerns
7
Perfluorooctanoic Acid (PFOA) and Fluorinated Telomers
Contact Us | Print Version
January 12, 2005: Draft PFOA Risk Assessment submitted to EPA Science Advisory Board for Peer Review: SAB meeting February 22-23, 2005.
PFOA stands for perfluorooctanoic acid, a synthetic (man-made) chemical that does not occur naturally in the environment. PFOA is sometimes called "C8." Companies use PFOA to make fluoropolymers, substances with special properties that have thousands of important manufacturing and industrial applications. Consumer products made with fluoropolymers include non-stick cookware and breathable, all-weather clothing. More BASIC INFORMATION about PFOA.
EPA began its investigation because PFOA is very persistent in the environment, was being found at very low levels both in the environment and in the blood of the general U.S. population, and caused developmental and other adverse effects in laboratory animals. EPA summarized its concerns and identified data gaps and uncertainties about PFOA in a notice published in the Federal Register.
8
Risk AssessmentYou will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.In January 2005, the EPA Office of Pollution Prevention and Toxics submitted a Draft Risk Assessment of the Potential Human Health Effects Associated With Exposure to Perfluorooctanoic Acid and Its Salts (PFOA) (PDF) (132pp, 450KB) to the EPA Science Advisory Board (SAB) for formal peer review. EPA sought this early stage scientific peer review from an outside panel of experts in order to ensure the most rigorous science is used in the Agency's ongoing evaluation of PFOA. That draft was preliminary and did not provide conclusions regarding potential levels of concern. The SAB reviewed the information that was available at the time, and suggested that the PFOA cancer data are consistent with the EPA Guidelines for Carcinogen Risk Assessment descriptor "likely to be carcinogenic to humans." Since its review, additional research has been conducted pertaining to the carcinogenicity of PFOA. EPA is still in the process of evaluating this information and has not made any definitive conclusions regarding potential risks, including cancer, at this time.
More information can be found on the SAB PFOA Review Panel Website.
EPA is not waiting for all of the answers to be known before taking action, however. In January 2006, EPA asked eight companies in the industry to commit to reducing PFOA from facility emissions and product content by 95 percent no later than 2010, and to work toward eliminating PFOA from emissions and product content no later than 2015. All eight of the invited companies submitted commitments to the Stewardship Program by March 1, 2006. Read more information on the PFOA 2010/15 Stewardship Program.
9
In 2006, former Administrator Stephen L. Johnson invited the eight major fluoropolymer and telomer manufacturers to join in a global stewardship program with two goals:To commit to achieve, no later than 2010, a 95% reduction, measured from a year 2000 baseline, in both facility emissions to all media of PFOA, precursor chemicals that can break down to PFOA, and related higher homologue chemicals, and product content levels of these chemicals.To commit to working toward the elimination of these chemicals from emissions and products by 2015.
Participating companies include: Arkema, Asahi, Ciba, Clariant, Daikin, 3M, DuPont, Solvay Solexis
Submitted baseline year 2000 data on emissions and product content at the end of October 2006.
Report annual progress toward goals each succeeding October and report progress in terms of both U.S. and global operations.
Companies also agreed to work cooperatively with EPA and establish scientifically credible analytical standards and laboratory methods to ensure comparability of reporting
10
Long chain perfluorinated acids (PFCAs/PFAs) observed in fauna in urban and remote locations
PFOA (perfluorooctanoic acid) C7F15C(O)OH
PFNA (perfluorononanoic acid) C8F17C(O)OH
PFDA (perfluorodecanoic acid) C9F19C(O)OH
PFUA (perfluoroundecanoic acid) C10F21C(O)OH
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
CC
FF
FF
FF
FF
FF
FF
PFPeA
OHO
F
F
3. What are PFOAs, PFCAs and PFOA?PerFluorinated Organic AcidsPerFluorinated Carboxylic AcidsPerFluorinated Octanoic Acid
11
12
In the far north... …in Polar Bears?
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
CC
FF
FF
FF
FF
FF
FF
PFPeA
OHO
F
FPFACs ng/gPFOA (8) 8.6PFNA (9) 180PFDA (10) 56PFUNA (11) 63 PFDoA (12) 6.2 PFTrA (13) 11PFTA (14) 0.51PFPeA (15) <0.5
Martin et al., EST 38 (2004) 373.
13
Facts:
No natural sources. Water-soluble PFCA salts used in fluoropolymer processing. Not released in major quantities. Presence of PFCAs in remote areas suggests atmospheric source.
The science (why) question?
Why are they here?
Where do long chain Perfluorocarboxylicacids
(PFCAs), CnF2n+1COOH come from?
Our hypothesis:
They are atmospheric degradation products from other long chain fluorinated compounds emitted to the atmosphere
14
22,000 liters of AFFF; ~300 kg of PFOS!
“Airport Foam Seeps into Creek”Toronto Star, June 10, 2000
15
Etobicoke Creek Fish Liver Samples; Jan 5, 2001 (spill + 7 months)
10.00 10.50 11.00 11.50 12.00 12.50 13.00 13.50 14.00Time0
100
%
0
100
%
0
100
%
0
100
%
0
100
%
0
100
%
0
100
%
0
100
%
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 713 > 669
1.46e3
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 613 > 569
4.46e3
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 563 > 519
1.82e3
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 513 > 469
3.03e3
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 499 > 99
2.52e5
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 413 > 369
1.06e3
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 399 > 99
2.18e3
JAN17-ETOBCREEK-DOWNSTREAM MRM of 12 Channels ES- 363 > 319
1.06e3
PFOS
PFDoA
PFUnA
PFDA
PFOA
PFHxS
PFHpA
PFTA
C12
C14
C10
C8
C7
C11
C8S
C6S
Moody, C.A., W.C. Kwan, J.W. Martin, D.C.G. Muir, and S.A. Mabury. 2001. Determination of Perfluorinated Surfactants in Surface Water Samples by Two Independent Analytical Techniques – Liquid Chromatography/Tandem Mass Spectrometry and 19F NMR. Analytical Chemistry. 73:2200-2206.
Moody, C.A., J. W. Martin, W. C. Kwan, D. C. G. Muir, and S. A. Mabury. 2002. Monitoring Perfluorinated Surfactants in Biota and Surface Water Samples Following an Accidental Fire-Fighting Foam Release into Etobicoke Creek. Environ. Sci. Technol. 36:545-551.
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
CHO
O
FF
FF
FF
FF
FF
FF
16
4. FTOH = fluorotelomer alcohol
2001 – FTOHs observed in atmosphere. Oxidation of FTOHs could be a source of PFCA
source (against conventional wisdom in atmospheric chemistry community).
CnF2n+1CH2CH2OH (straight chain)
4:2 FTOH = C4F9CH2CH2OH
6:2 FTOH = C6F13CH2CH2OH
8:2 FTOH = C8F17CH2CH2OH
10:2 FTOH = C10F21CH2CH2OH
17
PolyfluoroAlcohols are highly volatile!!!
5504503502501505050.01
.1
1
10
100
1000
10000
Molecular Mass
Log
P (
Pasc
als
)
Hydrocarbon Alcohols
Fluorotelomer Alcohols
HC data from Daubert & Danner; FTOH data from Lei et al, submitted J Chem Eng Data and Stock et al, ES&T in press.
FF
FFF
F
FFF
F
FF
F
C
FF
COH
F
F H
H
H
H
8:2 FTOH = 212 Pa
18
FTOH based coatings heavily used in consumer products;
*TRP Presentation toUSEPA OPPT. Nov 25, 2002US Public Docket AR226-1141
5x106 kg/yr40% in North America80% are in polymers*
Carpet Treatment
Polymer
Potential Sources?
Degradation
N C
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
CH2
H2COH
F
F
F F
F F
F F
F F
F F
F F
F
FF
C
F FC
OHH H
H H
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
CH2
H2C
F
F
OO
OO
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
CH2
H2C
F
F
O
F
F
F
F
F
F
F
F
F
F
F
F
F
FF
Urethane EtherEster
CH2
H2C
F
F
Residual
19
Three necessary conditions:
(1) FTOH survive atmospheric transport
(2) FTOH degrade to give PFCAs
(3) Magnitude of PFCA formation must be significant
Use a FTIR Smog chamber
Research Question:
Does atmospheric oxidation of FTOHs contribute significantly to PFCA burden in remote locations?
20
4. Experimental apparatus and setup
21
FTIR SMOG CHAMBERFTIR SMOG CHAMBER
o 140 L Pyrex chamber
o X/Cl2/N2/O2/black-lamps
o X/CH3ONO/NO/air/black-lamps
296 K, 700 Torr
22
23
24
25
Three necessary conditions:
(1) Do FTOHs survive atmospheric transport?
Measurement of k(OH+FTOH) – Why?
(2) Do FTOHs degrade to give PFCAs?
(3) Magnitude of PFCA formation must be significant?
Does atmospheric oxidation of FTOHs contribute significantly to PFCA burden in remote locations?
26
UV irradiation of
FTOH/reference/CH3ONO/NO/air mixtures
FTOH = 4:2 FTOH, 6:2 FTOH, or 8:2 FTOH
reference = C2H2 or C2H4
CH3ONO CH3O + NO
CH3O + O2 HCHO + HO2
HO2 + NO OH + NO2
OH + FTOH products (1)
OH + reference products (2)
27
OH + FTOH products (1)
OH + reference products (2)
][reference[OH]k]reference[
]FTOH[]OH[k]FTOH[
ss2ss1
dt
d
dt
d
Integration gives:
t[OH]k]reference[
]reference[t[OH]k
]FTOH[
]FTOH[ss2ss1
t
toLn
t
toLn
FTOH and reference have equal exposure to OH radicals, hence:
t
to
2
1
t
to
][reference
][reference
k
k
[FTOH]
[FTOH]LnLn
28
Loss of FTOH (squares = 4:2; circles = 6:2; triangles = 8:2) versus C2H2
and C2H4 on exposure to OH radicals in 700 Torr of air diluent at 296 K.
Ln ([Reference]to/[Reference]t)0.0 0.5 1.0 1.5
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Ln([
F(C
F2C
F2)
n(C
H2)
2OH
] to/[F
(CF
2CF
2)n(
CH
2)2O
H] t)
C2H2
C2H4
No discernable difference in reactivity of OH radicals towards 4:2, 6:2, and 8:2 FTOH
29
OH + CnF2n+1CH2CH2OH → products (10)
OH + C2H2 → products (11)
OH + C2H4 → products (12)
Linear fits give k10/k11 = 1.18±0.15 and k10/k12 = 0.131±0.018.
Using k11 = 8.5 x 10-13 and k12 = 8.66 x 10-12 gives
k10 = (1.00±0.13) x 10-12 and (1.13±0.16) x 10-12 cm3 molecule-1 s-1.
Final value, k10 = (1.07±0.22) x 10-12 cm3 molecule-1 s-1.
Ln ([Reference]to/[Reference]t)0.0 0.5 1.0 1.5
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Ln([
F(C
F2C
F2) n
(CH
2) 2
OH
] to/[F
(CF
2C
F2) n
(CH
2) 2
OH
] t)
C2H2
C2H4
30
Assuming:
atmospheric lifetime* for CH3CCl3 = 5.7 years
k(CH3CCl3 + OH) = 1.0 x 10-14 cm3 molecule-1 s-1
then
atmospheric lifetime* of F(CF2)nCH2CH2OH
(1.0x10-14)/(1.1x10-12) x 5.7 x 365 20 days.
* with respect to reaction with OH radicals
FTOH Lifetime Estimate
31
Other loss mechanisms?
Photolysis – should be negligible
Rainout – estimated to be negligible
Dry deposition – lifetime estimated to be 8 years
Homogeneous reactions other than with OH - unlikely
Atmospheric lifetime determined by reaction with OH and is approximately 20 days.
32
Ramifications of Lifetime
(1) Estimate flux of 100-1000 t yr-1 necessary to sustain observed atmospheric concentration.
(2) FTOH have negligible GWP
(3) Spatial distribution will be inhomogeneous
(4) FTOH will be transported to remote locations. Global average wind speed = 5 m s-1, 20 days = 8500 km.
33
Assuming 5m/s winds and a 20d lifetime, FTOHs could be transported over 8500 km
20 days… Long Enough for Long Range Transport?
Copenhagen to Detroit = 6500 km
34
Three necessary conditions:
(1) Do FTOHs survive atmospheric transport?
YES
(2) Do FTOHs degrade to give PFCAs?
(3) Magnitude of PFCA formation must be significant
Does atmospheric oxidation of FTOHs contribute significantly to PFCA burden in remote locations?
35
0.00
0.05
0.10
0.15
0.20
0.25
IR A
bso
rban
ce
0.00
0.05
0.10
0.15
0.20
0.25
0.00
0.02
0.04
0.06
0.08
Wavenumber (cm-1)
700 900 1100 1300 1500 1700 1900
0.00
0.05
0.10
0.15
(A) before irradiation
(B) 10 sec irradiation
(C) Product
(D) CF3(CF2)3CH2CHO
FTIR study of 4:2 FTOH oxidation
CF3(CF2)3CH2CHO
is the major primary
product from Cl
atom and OH
radical initiated
oxidation of 4:2 FTOH
36
FTOH Oxidation mechanism
CnF2n+1CH2CH2OH + OH CnF2n+1CH2C(•)HOH + H2O
CnF2n+1CH2C(•)HOH + O2 CnF2n+1CH2CHO + HO2
37
[CF3(CF2)3CH2CH2OH] / [CF3(CF2)3CH2CH2OH]0
0.0 0.2 0.4 0.6 0.8 1.0
[CF
3(C
F2) 3
CH
2C
HO
] /
[CF
3(C
F2) 3
CH
2C
H2O
H] 0
0.0
0.1
0.2
0.3
0.4
0.5
CnF2n+1CH2CHO is
reactive …
Gives secondary products …
38
[CF3(CF2)3CH2CHO] / [CF3(CF2)3CH2CH2OH]0
0.0 0.2 0.4 0.6 0.8 1.0
[pro
du
cts]
/ [C
F3(C
F2) 3
CH
2C
H2O
H] 0
0.0
0.1
0.2
0.3
0.4
0.5
[UN
KN
OW
N]
/ [C
F3(C
F2) 3
CH
2C
H2O
H] 0
0.00
0.05
0.10
0.15
0.20
0.25
CF3(CF2)3CHO
CF3(CF2)3CH2COOH
UNKNOWN
Secondary products:
CF3(CF2)3CHO,
CF3(CF2)3CH2COOH,
CF3(CF2)3C(O)OOH
39
FTOH Oxidation mechanism
CnF2n+1CH2CH2OH + OH CnF2n+1CH2C(•)HOH + H2O
CnF2n+1CH2C(•)HOH + O2 CnF2n+1CH2CHO + HO2
CnF2n+1CH2CHO + OH + O2 CnF2n+1CH2C(O)OO + H2O
CnF2n+1CH2C(O)OO + NO CnF2n+1CH2C(O)O + NO2
CnF2n+1CH2C(O)O CnF2n+1CH2 + CO2
CnF2n+1CH2 + O2 CnF2n+1CH2O2
CnF2n+1CH2O2 + NO CnF2n+1CH2O + NO2
CnF2n+1CH2O + O2 CnF2n+1CHO + HO2
40
[CF3(CF2)3CH2CHO] / [CF3(CF2)3CH2CH2OH]0
0.0 0.2 0.4 0.6 0.8 1.0
[pro
du
cts]
/ [C
F3(C
F2) 3
CH
2C
H2O
H] 0
0.0
0.1
0.2
0.3
0.4
0.5
[UN
KN
OW
N]
/ [C
F3(C
F2) 3
CH
2C
H2O
H] 0
0.00
0.05
0.10
0.15
0.20
0.25
CF3(CF2)3CHO
CF3(CF2)3CH2COOH
UNKNOWN
Secondary products:
C4F 9CHO,
C4F9CH2COOH
C4F9C(O)OOH
Secondary products are reactive …
41
0.00
0.02
0.04
0.06
0.08
0.00
0.10
0.20
0.30
0.40
0.50
0.60
IR A
bso
rba
nc
e
0.00
0.20
0.40
0.60
0.80
Wavenumber (cm-1)
1400 1600 1800 3500
0.00
0.10
0.20
0.30
(A) before irradiation
(B) 8.5 minutes irradiation
(C) residual
(D) CF3(CF2)3COOH
Tertiary products include:
COF2, CF3OH
C4F9COOH
Conclusion of FTIR experiments:
simulated atmospheric
oxidation of 4:2 FTOH (in absence
of NOx) gives a small (few %) yield
of C4F9COOH
42
in presence of NOx
4:2 FTOH C4F9CHO C4F9COOH
FTIR data shows that in gas phase:
in absence of NOx
4:2 FTOH C4F9CHO C4F9COOH
Likely explanation, presence of HO2 radicals in absence of NOx
Well established that CH3C(O)O2 + HO2 gives acetic acid and peracetic acid, ,presumably CxF2x+1C(O)O2 + HO2 reaction gives
CxF2x+1COOH and CxF2x+1COOOH.
Product study of CxF2x+1C(O)O2 + HO2 (x=1-4) to test this idea.
43
CnF2n+1C(O)O2 and HO2 radicals generated by UV irradiation of CnF2n+1CHO/H2/Cl2 mixtures in 100-700 Torr of air at 296±2 K:
Cl2 + h 2Cl
Cl + CnF2n+1CHO CnF2n+1CO + HCl
CnF2n+1CO + O2 + M CnF2n+1C(O)O2 + M
Cl + H2 H + HCl
H + O2 + M HO2 + M
CnF2n+1C(O)O2 + HO2 products
CnF2n+1C(O)O2 + CnF2n+2C(O)O2 products
As [H2]o/CnF2n+1CHO]o , products/products ,
Method
44
IR spectra obtained before (A) and after
(B) 55 s of irradiation of a mixture of 18.8 mTorr C2F5C(O)H,
218 mTorr Cl2 and
2.8 Torr H2 in 700
Torr of air. The consumption of
C2F5C(O)H was 63%.
45
PFCAs are products of
CxF2x+1C(O)O2 + HO2 reaction
Offers reasonable
explanation of observed PFCA formation in 4:2
FTOH expts.
46
Branching ratios in reactions of RC(O)O2 with HO2 radicals under ambient conditions (700-760 Torr, 2962K).
RC(O)O2 Products Reference
RC(O)OOH+O2 RC(O)OH+O
3
RC(O)O+O2+OH
CH3C(O)O2 0.40 0.16 0.20 0.08 0.40 0.16 [21]
CF3C(O)O2 0.09 0.04 0.38 0.04 0.56 0.05 This work
C2F5C(O)O2 < 0.06 0.24 0.04 0.76 0.04 [27]
C3F7C(O)O2 < 0.03 0.10 0.02 0.90 This work
C4F9C(O)O2 < 0.03 0.08 0.02 0.90 This work
47
CF2
CF3
O
OO HO2+
CF2
CF3
O
OO
OO
H
CF2
CF3
O
OO
O
OH
C2F5C(O)OH + O3
CF2
CF3
O
OO
OO
H
C2F5C(O)OOH + O 2
CF2
CF3
O
OO
OO
H
C2F5C(O)O + O2 + OH
a b c
48
49
Three necessary conditions:
(1) Do FTOHs survive atmospheric transport?
YES
(2) Do FTOHs degrade to give PFCAs?
YES
(3) Magnitude of PFCA formation must be significant
Does atmospheric oxidation of FTOHs contribute significantly to PFCA burden in remote locations?
50
FTOH flux into Northern Hemisphere = 100-1000 t yr-1
Assume molar PFCA yield from FTOH of 1-10%
Hence, PFCA flux = 1-100 t yr-1
Assume even spatial distribution
Hence, PFCA flux to Arctic = 0.1 - 10 t yr-1
Persistent organochlorine pesticides arctic loading =1.8 t yr-1
Organochlorine pesticides detectable in polar bears at a similar concentration to PFCAs ( 100-1000 ng/g)
Order of magnitude calculations suggest atmospheric oxidation of FTOHs is plausible explanation of PFCAs in
remote areas.
51
Three necessary conditions:
(1) Do FTOHs survive atmospheric transport?
YES
(2) Do FTOHs degrade to give PFCAs?
YES
(3) Magnitude of PFCA formation must be significant
Looks plausible … more work …
Does atmospheric oxidation of FTOHs contribute significantly to PFCA burden in remote locations?
52
53
Concentration of PFOA (in molecule cm-3) at 50 m. altitude in the University of Michigan 3D model (IMPACT) for January and July. The color scale extends from (A) 0 to 1.2x103 and (B) 0 to 3x103 molecule cm-3.
UIUC 2D model
54
55
Conclusions
1. The available evidence suggests, that the atmospheric oxidation of FTOHs makes a significant contribution to the PFCA burden in remote locations.
2. This is just the tip of the ice berg
3. The automobile industry uses large quantities of fluoropolymers but little, if any, FTOHs. Vehicles do not appear to be a source of PFCAs
56
The ”smog” quartet
57
The Atmospheric Science Group
Ch
F
Dk
FinDk Dk
Dk
Dk
Dk
Dk
Dk
RusD
Est
Est
US
58
Extra slides
59
60
8:2 FTOH = C8F17CH2CH2OH
PFNA = C8F17C(O)OH
PFOA = C7F15C(O)OH
Three necessary conditions:
(1) FTOH survive atmospheric transport
(2) FTOH degrade to give PFCAs
(3) Magnitude of PFCA formation must be significant
Use a FTIR Smog chamber
Research Question:
Does atmospheric oxidation of FTOHs contribute significantly to PFCA burden in remote locations?