Presentation on theme: "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 Nielsen Department of Chemistry."— Presentation transcript:
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 Nielsen Department of Chemistry University of Copenhagen www.cogci.dk
2 Acknowledgements Mads P. S. Andersen JPL-NASA, Pasadena, CA, USA Tim. J. Wallington, Mike. P. Hurley, Jim. C. Ball Ford Motor Company, Dearborn, MI, USA Scott. A. Mabury University of Toronto, Toronto, ON, Canada
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 = C n F 2n+1 CH 2 CH 2 OH (straight chain) 5.Atmospheric chemistry of FTOHs 6.Environmental Impacts and Conclusions 7.Discussions
5 Who am I? 1954 Born 1973 Began at UoC (chemistry and physics) 1974 Important Atmospheric Year 1978 M.Sc. and on to do a PhD at Risø Nat. Lab. 1978-95 Risø National Laboratory 1995-96 Ford Research Center Aachen, Germany 1996-99 Risø National Laboratory 1999-? Professor at UoC 2007 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 UsContact Us | Print VersionPrint Version January 12, 2005: Draft PFOA Risk Assessment submitted to EPA Science Advisory Board for Peer Review: SAB meeting February 22-23, 2005.Draft PFOA Risk Assessment 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.More BASIC INFORMATION about PFOAFederal Register
8 Risk Assessment You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.EPA's PDF page 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. Draft Risk Assessment of the Potential Human Health Effects Associated With Exposure to Perfluorooctanoic Acid and Its Salts (PFOA) (PDF)Science Advisory Board (SAB)EPA Guidelines for Carcinogen Risk AssessmentSAB PFOA Review Panel WebsitePFOA 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) C 7 F 15 C(O)OH PFNA (perfluorononanoic acid) C 8 F 17 C(O)OH PFDA (perfluorodecanoic acid) C 9 F 19 C(O)OH PFUA (perfluoroundecanoic acid) C 10 F 21 C(O)OH 3. What are PFOAs, PFCAs and PFOA? PerFluorinated Organic Acids PerFluorinated Carboxylic Acids PerFluorinated Octanoic Acid
12 In the far north... …in Polar Bears? PFACsng/g PFOA (8)8.6 PFNA (9)180 PFDA (10)56 PFUNA (11)63 PFDoA (12)6.2 PFTrA (13)11 PFTA (14)0.51 PFPeA (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), C n F 2n+1 COOH 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) 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.
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). C n F 2n+1 CH 2 CH 2 OH (straight chain) 4:2 FTOH = C 4 F 9 CH 2 CH 2 OH 6:2 FTOH = C 6 F 13 CH 2 CH 2 OH 8:2 FTOH = C 8 F 17 CH 2 CH 2 OH 10:2 FTOH = C 10 F 21 CH 2 CH 2 OH
17 PolyfluoroAlcohols are highly volatile!!! HC data from Daubert & Danner; FTOH data from Lei et al, submitted J Chem Eng Data and Stock et al, ES&T in press. 8:2 FTOH = 212 Pa
18 FTOH based coatings heavily used in consumer products; *TRP Presentation to USEPA OPPT. Nov 25, 2002 US Public Docket AR226-1141 5x10 6 kg/yr 40% in North America 80% are in polymers*
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?
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/CH 3 ONO/NO/air mixtures FTOH = 4:2 FTOH, 6:2 FTOH, or 8:2 FTOH reference = C 2 H 2 or C 2 H 4 CH 3 ONO CH 3 O + NO CH 3 O + O 2 HCHO + HO 2 HO 2 + NO OH + NO 2 OH + FTOH products(1) OH + reference products(2)
27 OH + FTOH products(1) OH + reference products(2) Integration gives: FTOH and reference have equal exposure to OH radicals, hence:
28 Loss of FTOH (squares = 4:2; circles = 6:2; triangles = 8:2) versus C 2 H 2 and C 2 H 4 on exposure to OH radicals in 700 Torr of air diluent at 296 K. No discernable difference in reactivity of OH radicals towards 4:2, 6:2, and 8:2 FTOH
29 OH + C n F 2n+1 CH 2 CH 2 OH → products (10) OH + C 2 H 2 → products (11) OH + C 2 H 4 → products (12) Linear fits give k 10 /k 11 = 1.18±0.15 and k 10 /k 12 = 0.131±0.018. Using k 11 = 8.5 x 10 -13 and k 12 = 8.66 x 10 -12 gives k 10 = (1.00±0.13) x 10 -12 and (1.13±0.16) x 10 -12 cm 3 molecule -1 s -1. Final value, k 10 = (1.07±0.22) x 10 -12 cm 3 molecule -1 s -1.
30 Assuming: atmospheric lifetime* for CH 3 CCl 3 = 5.7 years k(CH 3 CCl 3 + OH) = 1.0 x 10 -14 cm 3 molecule -1 s -1 then atmospheric lifetime* of F(CF 2 ) n CH 2 CH 2 OH (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 FTIR study of 4:2 FTOH oxidation CF 3 (CF 2 ) 3 CH 2 CHO is the major primary product from Cl atom and OH radical initiated oxidation of 4:2 FTOH
36 FTOH Oxidation mechanism C n F 2n+1 CH 2 CH 2 OH + OH C n F 2n+1 CH 2 C()HOH + H 2 O C n F 2n+1 CH 2 C()HOH + O 2 C n F 2n+1 CH 2 CHO + HO 2
37 C n F 2n+1 CH 2 CHO is reactive … Gives secondary products …
39 FTOH Oxidation mechanism C n F 2n+1 CH 2 CH 2 OH + OH C n F 2n+1 CH 2 C()HOH + H 2 O C n F 2n+1 CH 2 C()HOH + O 2 C n F 2n+1 CH 2 CHO + HO 2 C n F 2n+1 CH 2 CHO + OH + O 2 C n F 2n+1 CH 2 C(O)OO + H 2 O C n F 2n+1 CH 2 C(O)OO + NO C n F 2n+1 CH 2 C(O)O + NO 2 C n F 2n+1 CH 2 C(O)O C n F 2n+ 1 CH 2 + CO 2 C n F 2n+ 1 CH 2 + O 2 C n F 2n+ 1 CH 2 O 2 C n F 2n+ 1 CH 2 O 2 + NO C n F 2n+ 1 CH 2 O + NO 2 C n F 2n+ 1 CH 2 O + O 2 C n F 2n+ 1 CHO + HO 2
40 Secondary products: C 4 F 9 CHO, C 4 F 9 CH 2 COOH C 4 F 9 C(O)OOH Secondary products are reactive …
41 Tertiary products include: COF 2, CF 3 OH C 4 F 9 COOH Conclusion of FTIR experiments: simulated atmospheric oxidation of 4:2 FTOH (in absence of NO x ) gives a small (few %) yield of C 4 F 9 COOH
42 in presence of NO x 4:2 FTOH C 4 F 9 CHO C 4 F 9 COOH FTIR data shows that in gas phase: in absence of NO x 4:2 FTOH C 4 F 9 CHO C 4 F 9 COOH Likely explanation, presence of HO 2 radicals in absence of NO x Well established that CH 3 C(O)O 2 + HO 2 gives acetic acid and peracetic acid,, presumably C x F 2x+1 C(O)O 2 + HO 2 reaction gives C x F 2x+1 COOH and C x F 2x+1 COOOH. Product study of C x F 2x+1 C(O)O 2 + HO 2 (x=1-4) to test this idea.
43 C n F 2n+1 C(O)O 2 and HO 2 radicals generated by UV irradiation of C n F 2n+1 CHO/H 2 /Cl 2 mixtures in 100-700 Torr of air at 296±2 K: Cl 2 + h 2Cl Cl + C n F 2n+1 CHO C n F 2n+1 CO + HCl C n F 2n+1 CO + O 2 + M C n F 2n+1 C(O)O 2 + M Cl + H 2 H + HCl H + O 2 + M HO 2 + M C n F 2n+1 C(O)O 2 + HO 2 products C n F 2n+1 C(O)O 2 + C n F 2n+2 C(O)O 2 products As [H 2 ] o /C n F 2n+1 CHO] o , products/products , Method
44 IR spectra obtained before (A) and after (B) 55 s of irradiation of a mixture of 18.8 mTorr C 2 F 5 C(O)H, 218 mTorr Cl 2 and 2.8 Torr H 2 in 700 Torr of air. The consumption of C 2 F 5 C(O)H was 63%.
45 PFCAs are products of C x F 2x+1 C(O)O 2 + HO 2 reaction Offers reasonable explanation of observed PFCA formation in 4:2 FTOH expts.
46 Branching ratios in reactions of RC(O)O 2 with HO 2 radicals under ambient conditions (700-760 Torr, 296 2K). RC(O)O 2 Products Reference RC(O)OOH+O 2 RC(O)OH+O 3 RC(O)O+O 2 +OH CH 3 C(O)O 2 0.40 0.160.20 0.080.40 0.16 CF 3 C(O)O 2 0.09 0.040.38 0.040.56 0.05This work C 2 F 5 C(O)O 2 < 0.060.24 0.040.76 0.04 C 3 F 7 C(O)O 2 < 0.030.10 0.02 0.90This work C 4 F 9 C(O)O 2 < 0.030.08 0.02 0.90This work
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?
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 1.2x10 3 and (B) 0 to 3x10 3 molecule cm -3. UIUC 2D model
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
60 8:2 FTOH = C 8 F 17 CH 2 CH 2 OH PFNA = C 8 F 17 C(O)OH PFOA = C 7 F 15 C(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?