Perfluorooctanesulfonic acid

Perfluorooctanesulfonic acid
PFOS molecule
Names
Systematic IUPAC name
1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptadecafluoro-1-octanesulfonic acid[1]
Other names
PFOS
Identifiers
1763-23-1 YesY
ChEBI CHEBI:39421 YesY
ChemSpider 67068 YesY
EC Number 217-179-8
Jmol interactive 3D Image
KEGG C18142 YesY
PubChem 74483
Properties
C8HF17O3S
Molar mass 500.13 g/mol
Boiling point 133 °C (271 °F; 406 K) at 6 torr
Acidity (pKa) <<0[2][3]
Hazards
Toxic (T)
Dangerous for the environment (N)
R-phrases R61, R20/22, R40, R48/25, R64, R51/53
S-phrases S53, S45, S61
Related compounds
Related compounds
 Perfluorooctanoic acid (PFOA), Perfluorobutanesulfonic acid (PFBS), Perfluorooctanesulfonamide (PFOSA), Perfluorononanoic acid (PFNA)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Perfluorooctanesulfonic acid or perfluorooctane sulfonate (PFOS) is a man-made fluorosurfactant and global pollutant. PFOS was the key ingredient in Scotchgard, a fabric protector made by 3M, and numerous stain repellents. It was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants in May 2009.[4] PFOS can be synthesized in industrial production or result from the degradation of precursors. PFOS levels that have been detected in wildlife are considered high enough to affect health parameters, and recently higher serum levels of PFOS were found to be associated with increased risk of chronic kidney disease in the general US population.[5] "This association was independent of confounders such as age, sex, race/ethnicity, body mass index, diabetes, hypertension, and serum cholesterol level."[5]

History

In 1949, 3M began producing PFOS-based compounds by electrochemical fluorination resulting in the synthetic precursor perfluorooctane sulfonyl fluoride.[6] In 1968, organofluorine content was detected in the blood serum of consumers, and in 1976 it was suggested to be PFOA or a related compound such as PFOS.[7][8][9] In 1997, 3M detected PFOS in blood from global blood banks.[10] In 1999, the U.S. Environmental Protection Agency began investigating perfluorinated compounds after receiving data on the global distribution and toxicity of PFOS, the key ingredient in Scotchgard.[11] For these reasons, and USEPA pressure,[12] the primary American producer of PFOS, 3M, announced, in May 2000, the phaseout of the production of PFOS, PFOA, and PFOS-related products.[13] PFOS and PFOS-related chemicals are currently produced in China.

Advances in analytical chemistry in recent years have allowed the routine detection of low- and sub-ppb levels of PFOS in food, wildlife, and humans.

Synthesis

Two primary methods are used for the industrial scale production of PFOS: electrophilic (or electrochemical) fluorination (ECF) and telomerisation. ECF is an electrolysis production method where a precursor of perfluoroctanesulfonyl fluoride is dispersed in a solution of hydrofluoric acid and electrified. This production method, whilst economic and mainly results in PFOS, also results in shorter chain perfluoroalkyl substances being formed. PFOS predominates in the resultant mixture, however if the reaction is allowed to continue this begins to favour the production of shorter chain PFAS. A distinct isomer ratio has been observed in PFOS produced by ECF, in the order of 70% linear PFOS, 25% branched and 5% terminal; this is not a function of the production process but rather that the precursor also exhibits this isomer ratio. ECF was the means by which 3M produced PFOS up until May 2000 when the company announced a phaseout of production along with other PFOS related products.

Telomerisation involves constructing the PFOS molecule using short chain (often 2-carbon) moieties and adding a sulfonate group as a final step. This production process results in 100% linear PFOS. This production method, whilst cleaner and resulting in a much more pure product than ECF, is not known to have been widely used except for production of reagent grade PFOS and analytical standards.

Properties

The C8F17 subunit of PFOS is hydrophobic and lipophobic, like other fluorocarbons, while the sulfonic acid/sulfonate group adds polarity. PFOS is an exceptionally stable compound in industrial applications and in the environment because of the effect of aggregate carbon–fluorine bonds. PFOS is a fluorosurfactant that lowers the surface tension of water more than that of hydrocarbon surfactants. Although attention is typically focused on the straight-chain isomer (n-PFOS), which is dominant in commercial mixtures and environmental samples, there are 89 linear and branched congeners that are expected to have different physical, chemical, and toxicological properties.[14][15][16][17][18][19][20][21]

Uses

Perfluorooctanesulfonic acid is usually used as the sodium or potassium salts.

The most important emission sources of PFOS are metal plating and fire-fighting foams.[22]

Health effects in humans and wildlife

According to a 2002 study by the Environmental Directorate of the OECD "PFOS is persistent, bioaccumulative and toxic to mammalian species."[23]

In 2008, it was shown to affect the immune system of male mice at a blood serum concentration of ~90 parts per billion, raising the possibility that highly exposed people and wildlife are immunocompromised.[24] Chicken eggs dosed at 1 milligram per kilogram (or 1000 parts per billion) of egg weight developed into juvenile chickens with an average of ~150 parts per billion in blood serum—and showed brain asymmetry and decreased immunoglobulin levels.[25] Occupationally exposed individuals may have an average level of PFOS over 1000 parts per billion, and a small segment of individuals in the upper range of the general population may be over the 91.5 parts per billion level.[24] A variety of wildlife species have had PFOS levels measured in egg, liver, kidney, serum, and plasma samples and some of the highest recorded values as of January 2006 are listed below.[26]

Species Geography Year Sample PFOS (ppb)
Bald eagle Midwestern USA 1990–93 plasma 2,200
Brandt's cormorant California, USA 1997 liver 970
Guillemot Baltic Sea 1997 egg 614
Carrion crow Tokyo Bay, Japan 2000 liver 464
Red-throated loon North Carolina, USA 1998 liver 861
Polar bear Sanikiluaq, Nunavut 2002 liver 3,100
Harbor seal Dutch Wadden Sea, Denmark 2002 muscle 2,725
Bottlenose dolphin Charleston, South Carolina, USA 2003 plasma 1,315
Common dolphin Mediterranean Sea, Italy 1998 liver 940
Mink Michigan, USA 2000–01 liver 59,500

The levels observed in wild animals are considered sufficient to "alter health parameters".[27][28] In people, the highest exposures to PFOS in blood have been 12,830 parts per billion for occupational exposure and 656 parts per billion[29]—or possibly 1,656 parts per billion[30]—in a consumer.

In animal studies PFOS can cause cancer, delays in physical development, stunted growth, endocrine disruption, and neonatal mortality; Neonatal mortality might be the most dramatic result of laboratory animal tests with PFOS.[31] Female mice with blood levels of PFOS at ranges found in wildlife and humans demonstrated higher mortality when infected with influenza A.[32] PFOS reduces the birth size of animals;[33] in humans, correlations between PFOS levels and reduced fetal growth are inconsistent.[34]

PFOS is detected in the blood serum of almost all people in the U.S., and concentrations have been decreasing over time. In contrast, PFOS blood levels appear to be rising in China.[35] PFOS levels in pregnant women have been associated with preeclampsia.[36] Increased levels have been associated with altered thyroid hormone levels in adults[37] and an increased risk of elevated cholesterol.[38][39] Levels in US children aged 12–15 were associated with an increased risk (60% over the interquartile range) of attention deficit hyperactivity disorder (ADHD).[40]

Precursors

Volatile sulfonamide PFOS precursors include N-methyl perfluorooctane sulfonamidoethanol (N-MeFOSE), a carpet stain repellent, and N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE), a paper treatment.[41] Perfluorooctanesulfonamide is a precursor.[42] About 50 precursors were named in the 2004 proposed Canadian ban on PFOS.[43] Later, the OECD came up with a document containing a list of 20 pages with potential precursors to PFOS.[44]

Regulation

In May 2009, PFOS was included in Annex B of the Stockholm Convention on persistent organic pollutants by the Fourth Conference of Parties.[4] In 2008 Canada proposed a ban on PFOS, only the second chemical proposed for a complete ban under the Canadian Environmental Protection Act.[45]

Based on an OECD study on PFOS[23] and a risk assessment by Europe's Scientific Committee on Health and Environmental Risks[46] the European Union practically banned the use of PFOS in finished and semi-finished products in 2006 (maximum content of PFOS: 0.005% by weight).[47] However, PFOS use for industrial applications (e.g. photolithography, mist suppressants for hard chromium plating, hydraulic fluids for aviation) was exempted. In 2009 this directive was incorporated into the REACH regulation.[48] In the summer of 2010 PFOS was added to the regulation on persistent organic pollutants and the threshold was lowered to max. 0.001% by weight (10 mg/kg).[49]

See also

References

  1. ↑ http://Chemspider.com/Chemical-structure.67068.html
  2. ↑ Cheng J, Psillakis E, Hoffmann MR, Colussi AJ (July 2009). "Acid dissociation versus molecular association of perfluoroalkyl oxoacids: Environmental implications". J. Phys. Chem. A 113 (29): 8152–8156. doi:10.1021/jp9051352. PMID 19569653.
  3. ↑ Rayne S, Forest K, Friesen KJ (2009). "Extending the semi-empirical PM6 method for carbon oxyacid pKa prediction to sulfonic acids: Application towards congener-specific estimates for the environmentally and toxicologically relevant C1 through C8 perfluoroalkyl derivatives". Nature Precedings.
  4. 1 2 Governments unite to step-up reduction on global DDT reliance and add nine new chemicals under international treaty. Geneva: Stockholm Convention Secretariat. 8 May 2008.
  5. 1 2 Shankar, Anoop; Jie Xiao; Alan Ducatman (2011-10-15). "Perfluoroalkyl Chemicals and Chronic Kidney Disease in US Adults". American Journal of Epidemiology 174 (8): 893–900. doi:10.1093/aje/kwr171. PMID 2187360. Retrieved 2011-10-10.
  6. ↑ Paul AG, Jones KC, Sweetman AJ (January 2009). "A first global production, emission, and environmental inventory for perfluorooctane sulfonate". Environ. Sci. Technol. 43 (2): 386–92. doi:10.1021/es802216n. PMID 19238969.
  7. ↑ Kennedy GL, Butenhoff JL, Olsen GW, et al. (2004). "The toxicology of perfluorooctanoate". Crit. Rev. Toxicol. 34 (4): 351–84. doi:10.1080/10408440490464705. PMID 15328768.
  8. ↑ Giesy JP, Kannan K (April 2002). "Perfluorochemical surfactants in the environment". Environ. Sci. Technol. 36 (7): 146A–152A. doi:10.1021/es022253t. PMID 11999053.
  9. ↑ Lau C, Butenhoff JL, Rogers JM (July 2004). "The developmental toxicity of perfluoroalkyl acids and their derivatives". Toxicol. Appl. Pharmacol. 198 (2): 231–41. doi:10.1016/j.taap.2003.11.031. PMID 15236955.
  10. ↑ "The Inside Story: 3M and Scotchgard". Environmental Working Group. Retrieved 29 May 2009.
  11. ↑ Aziz Ullah. "The Fluorochemical Dilemma: What the PFOS/PFOA fuss is all about" Cleaning & Restoration. www.ascr.org, (October, 2006). Accessed October 25, 2008.
  12. ↑ Lee, Jennifer 8. (15 April 2003). "E.P.A. Orders Companies to Examine Effects of Chemicals". The New York Times. Retrieved 15 May 2009.
  13. ↑ 3M: "PFOS-PFOA Information: What is 3M Doing?" Accessed October 25, 2008.
  14. ↑ Rayne S, Forest K, Friesen KJ (2008). "Congener-specific numbering systems for the environmentally relevant C1 through C8 perfluorinated homologue groups of alkyl sulfonates, carboxylates, telomer alcohols, olefins, and acids, and their derivatives". Journal of Environmental Science and Health, Part A: Toxic / Hazardous Substances and Environmental Engineering 43 (12): 1391–1401. doi:10.1080/10934520802232030.
  15. ↑ Rayne S, Forest K, Friesen KJ (2009). "Estimated bioconcentration factors (BCFs) for the C1 through C8 perfluorinated alkylsulfonic acid (PFSA) and alkylcarboxylic acid (PFCA) congeners". Journal of Environmental Science and Health, Part A: Toxic / Hazardous Substances and Environmental Engineering 44 (6): 598–604. doi:10.1080/10934520902784641.
  16. ↑ Rayne S, Forest K, Friesen KJ (2009). "Linear free energy relationship based estimates for the congener specific relative reductive defluorination rates of perfluorinated alkyl compounds". Journal of Environmental Science and Health, Part A: Toxic / Hazardous Substances and Environmental Engineering 44 (9): 866–879. doi:10.1080/10934520902958625.
  17. ↑ Rayne S, Forest K, Friesen KJ (2009). "Estimated congener specific gas phase atmospheric behavior and fractionation of perfluoroalkyl compounds: Rates of reaction with atmospheric oxidants, air-water partitioning, and wet/dry deposition lifetimes". Journal of Environmental Science and Health, Part A: Toxic / Hazardous Substances and Environmental Engineering 44 (10): 936–954. doi:10.1080/10934520902996815.
  18. ↑ Rayne S, Forest K (2009). "Perfluoroalkyl sulfonic and carboxylic acids: A critical review of physicochemical properties, levels and patterns in waters and waste waters, and treatment methods". Journal of Environmental Science and Health, Part A: Toxic / Hazardous Substances and Environmental Engineering 44 (12): 1145–1199. doi:10.1080/10934520903139811.
  19. ↑ Rayne S, Forest K (2009). "Congener specific organic carbon normalized soil and sediment-water partitioning coefficients for the C1 through C8 perfluoroalkyl carboxylic and sulfonic acids". Journal of Environmental Science and Health, Part A: Toxic / Hazardous Substances and Environmental Engineering 44 (13): 1374–1387. doi:10.1080/10934520903217229.
  20. ↑ Rayne S, Forest K (2009). "An assessment of organic solvent based equilibrium partitioning methods for predicting the bioconcentration behavior of perfluorinated sulfonic acids, carboxylic acids, and sulfonamides". Nature Precedings.
  21. ↑ Rayne S, Forest K (2009). "A comparative assessment of octanol-water partitioning and distribution constant estimation methods for perfluoroalkyl carboxylates and sulfonates". Nature Precedings. doi:10.1038/npre.2009.3282.2.
  22. ↑ http://www.environment-switzerland.ch/uw-0922-e
  23. 1 2 OECD (2002). "Hazard Assessment of Perfluorooctane Sulfonate (PFOS) and its Salt". ENV/JM/RD(2002)17/FINAL (page 5).
  24. 1 2 Betts KS (July 2008). "Not immune to PFOS effects?". Environ. Health Perspect. 116 (7): A290. doi:10.1289/ehp.116-a290a. PMC 2453185. PMID 18629339.
  25. ↑ Peden-Adams, M.; Stuckey, J.; Gaworecki, K.; Berger-Ritchie, J.; Bryant, K.; Jodice, P.; Scott, T.; Ferrario, J.; Guan, B.; Vigo, C.; Boone, J. S.; McGuinn, W. D.; Dewitt, J. C.; Keil, D. E. (2009). "Developmental toxicity in white leghorn chickens following in ovo exposure to perfluorooctane sulfonate (PFOS)". Reproductive toxicology (Elmsford, N.Y.) 27 (3–4): 307–318. doi:10.1016/j.reprotox.2008.10.009. PMID 19071210.
  26. ↑ Houde M, Martin JW, Letcher RJ, Solomon KR, Muir DC (June 2006). "Biological monitoring of polyfluoroalkyl substances: A review". Environ. Sci. Technol. 40 (11): 3463–73. doi:10.1021/es052580b. PMID 16786681. Supporting Information (PDF).
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  28. ↑ Peden-Adams et al. (June 2008). In PFAA Days II (PDF). p. 28.
  29. ↑ Fromme H, Tittlemier SA, Völkel W, Wilhelm M, Twardella D (May 2009). "Perfluorinated compounds—exposure assessment for the general population in Western countries". Int. J. Hyg. Environ. Health 212 (3): 239–70. doi:10.1016/j.ijheh.2008.04.007. PMID 18565792.
  30. ↑ Olsen GW, Church TR, Miller JP, et al. (December 2003). "Perfluorooctanesulfonate and other fluorochemicals in the serum of American Red Cross adult blood donors". Environ. Health Perspect. 111 (16): 1892–901. doi:10.1289/ehp.6316. PMC 1241763. PMID 14644663.
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  32. ↑ Guruge KS, Hikono H, Shimada N, Murakami K, Hasegawa J, Yeung LW, Yamanaka N, Yamashita N (December 2009). "Effect of perfluorooctane sulfonate (PFOS) on influenza A virus-induced mortality in female B6C3F1 mice". J Toxicol Sci 34 (6): 687–91. doi:10.2131/jts.34.687. PMID 19952504.
  33. ↑ Betts K (November 2007). "PFOS and PFOA in humans: new study links prenatal exposure to lower birth weight". Environ Health Perspect. 115 (11): A550. doi:10.1289/ehp.115-a550a. PMC 2072861. PMID 18007977.
  34. ↑ Washino N, Saijo Y, Sasaki S, et al. (April 2009). "Correlations between prenatal exposure to perfluorinated chemicals and reduced fetal growth". Environ. Health Perspect. 117 (4): 660–7. doi:10.1289/ehp.11681. PMC 2679613. PMID 19440508.
  35. ↑ Renner, Rebecca (2008). "PFOS phaseout pays off". Environ. Sci. Technol. 42 (13): 4618. doi:10.1021/es0871614. PMID 18677976.
  36. ↑ Stein CR, Savitz DA, Dougan M (October 2009). "Serum levels of perfluorooctanoic acid and perfluorooctane sulfonate and pregnancy outcome". Am. J. Epidemiol. 170 (7): 837–46. doi:10.1093/aje/kwp212. PMID 19692329.
  37. ↑ Dallaire R, Dewailly E, Pereg D, Dery S, Ayotte P (September 2009). "Thyroid function and plasma concentrations of polyhalogenated compounds in Inuit adults". Environ. Health Perspect. 117 (9): 1380–6. doi:10.1289/ehp.0900633. PMC 2737013. PMID 19750101.
  38. ↑ Steenland K, Tinker S, Frisbee S, Ducatman A, Vaccarino V (November 2009). "Association of perfluorooctanoic acid and perfluorooctane sulfonate with serum lipids among adults living near a chemical plant". Am. J. Epidemiol. 170 (10): 1268–78. doi:10.1093/aje/kwp279. PMID 19846564.
  39. ↑ Nelson JW, Hatch EE, Webster, TF (2009). "Exposure to Polyfluoroalkyl Chemicals and Cholesterol, Body Weight, and Insulin Resistance in the General U.S. Population" (PDF). Environ. Health Perspect. 118 (2): 197–202. doi:10.1289/ehp.0901165. PMC 2831917. PMID 20123614.
  40. ↑ Hoffman K, Webster TF, Weisskopf MG, Weinberg J, Vieira VM (2010). "Exposure to Polyfluoroalkyl Chemicals and Attention Deficit Hyperactivity Disorder in U.S. Children Aged 12-15 Years". Environ. Health Perspect. 118 (12): 1762–7. doi:10.1289/ehp.1001898. PMC 3002197. PMID 20551004.
  41. ↑ Renner R (March 2004). "Perfluorinated sources outside and inside". Environ. Sci. Technol. 38 (5): 80A. doi:10.1021/es040387w. PMID 15046317.
  42. ↑ Lehmler, HJ (March 2005). "Synthesis of environmentally relevant fluorinated surfactants—a review". Chemosphere 58 (11): 1471–96. doi:10.1016/j.chemosphere.2004.11.078. PMID 15694468.
  43. ↑ Pelley J (December 2004). "Canada moves to eliminate PFOS stain repellents". Environ. Sci. Technol. 38 (23): 452A. doi:10.1021/es040676k. PMID 15597866.
  44. ↑ "Lists of PFOS, PFAS, PFCA, related compounds and chemicals that may degrade to PFCA". OECD. August 2007. |section= ignored (help)
  45. ↑ Environmental Defence: "Stain Repellant Chemical, PFOS, Listed for “Virtual Elimination”" News Release. (April 21, 2008). Accessed October 26, 2008.
  46. ↑ SCHER (2005). "RPA's report "Perfluorooctane Sulphonates Risk reduction strategy and analysis of advantages and drawbacks"". Scientific Committee on Health and Environmental Risks, European Commission.
  47. ↑ DIRECTIVE 2006/122/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 12 December 2006
  48. ↑ COMMISSION REGULATION (EC) No 552/2009 of 22 June 2009
  49. ↑ COMMISSION REGULATION (EU) No 757/2010 of 24 August 2010

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