Perfluorooctanoic acid
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| Perfluorooctanoic acid | |
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| General | |
| Systematic name | pentadecafluorooctanoic acid |
| Other names | perfluorooctanoic acid PFOA |
| Molecular formula | C8HF15O2 |
| SMILES | OC(=O)C(F)(F)C(F)(F)C(F)(F)C (F)(F)C(F)(F)C(F)(F)C(F)(F)F |
| Molar mass | 414.07 g/mol |
| Appearance | colorless liquid |
| CAS number | [335-67-1] |
| Properties | |
| Density and phase | ? g/cm3 |
| Solubility in water | soluble |
| Other solvents | polar organic solvents |
| Melting point | 55-56 °C |
| Boiling point | 189 °C (736 mm Hg) |
| Acidity (pKa) | ? |
| Viscosity | ? cP at ? °C |
| Structure | |
| Molecular shape | Carboxylic acid |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | strong acid |
| R/S statement | R: 22-34-52/53 S: 26-36/37/39-45 |
| RTECS number | RH0781000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | CF3CO2H |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Perfluorooctanoic acid (PFOA), also known as C8, is an artificial acid that has many industrial uses. PFOA can designate the acid itself or its principal salts (like ammonium perfluorooctanoate).
Perfluorooctane sulfonate is a related compound, used as a surfactant.
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[edit] Uses
PFOA - pentadecafluorooctanoic acid is an industrial surfactant. One of the most common uses of PFOA is for processing polytetrafluoroethylene PTFE, most widely recognized under the brand name Teflon by DuPont. PFOA, usually pronounced "pee-fo-ah", is also a by-product of the telomerization process taking place on industrial scale in Asia, North America, and Europe by several international chemical companies. The telomerization process produces perfluorinated alcohol, which is commonly used in many household surface finishes and indirect contact applications in flexible food packaging. PFOA by-product is also in the fabrication of water- and stain-resistant clothes and other materials, including the products StainMaster, and Gore-Tex. (3M Scotchgard(tm) complied with a voluntary phase out of PFOS, a competing technology to the Zonyl trade name). PFOA by-product is also found in aqueous film forming foam (AFFF), a component of fire-fighting foams.
Fluorotelomer compounds (produced by several international companies) are used in food packaging to make them resistant to grease; however, these compounds may form PFOA when ingested. According to a USA Today article, these compounds have been used in "microwave popcorn bags, fast food and candy wrappers, and pizza box liners" [2]. In particular, microwave popcorn bags have the most fluorotelomers of any food wrapper, and the high cooking temperatures increase the migration of these chemicals into the popcorn oil. It is estimated that microwave popcorn may account for more than 20% of the average PFOA levels measured in American residents. Its elimination half-life is reported as being 4 years [3].
As discussed below with regard to health concerns, DuPont has agreed to eliminate the use of PFOA completely by 2015 [4].
[edit] Health concerns
The durability of PFOA prevents it from breaking down once in the environment, leading to widespread buildup and bioaccumulation in food chains. Traces of PFOA-family chemicals can now be found in the blood of nearly all Americans and in the environment worldwide. Scientists do not yet know how the chemicals are transported or exactly how dangerous they are to humans, although concerns about these issues caused its major manufacturer, 3M, to announce in May 2000 that it would cease producing the chemical. DuPont, one of the largest users of PFOA, then built its own plant in Fayetteville, North Carolina to manufacture PFOA.
DuPont has used PFOA for over 50 years at its Washington Works plant near Belpre, Ohio. Area residents sued DuPont in 2001, claiming the chemical contaminated area drinking water. As part of the settlement, DuPont is paying for blood tests and health surveys of residents believed to be affected. Up to 60,000 people are expected to take part in the study, which will be reviewed by epidemiologists to determine if there are any long-term health effects.
In 2004, DuPont came under investigation by the Environmental Protection Agency (EPA) for allegedly covering up knowledge of possible health effects of PFOA exposure in a study of pregnant employees, including evidence of PFOA in umbilical cord blood.
The EPA pursued charges against DuPont for failure to report violations filed under the Toxic Substances Control Act and the Resource Conservation and Recovery Act. On December 13, 2005 DuPont announced a settlement with the EPA in which DuPont will pay US$10.25 million in fines and an additional US$6.25 million for two supplemental environmental projects without any admission of liability.
Some public watchdog groups are raising the alarm about PFOA. The Environmental Working Group says, in an online report titled "PFCs: A Family of Chemicals that Contaminate the Planet", that "PFCs seem destined to supplant DDT, PCBs, dioxin, and other chemicals as the most notorious, global chemical contaminants ever produced." Still, as with most problematic chemicals a strict scientific proof that PFOA is toxic to human beings (and not only to rats) has not yet been accomplished. Still there are serious concerns and, as a prevention measure, a ban is being discussed.
On January 25, 2006, the EPA announced a long-term, voluntary program to reduce PFOA emissions and to eliminate PFOA use in products by the year 2015. While a New York Times article the next day claimed that companies would "stop using" PFOA, the EPA described its objective as "elimination of PFOA...from emissions and products" but not as a chemical intermediate to produce other substances.
On February 15, 2006, the EPA's Science Advisory Board voted to approve a recommendation that PFOA should be considered a likely carcinogen.
On November 21, 2006, EPA ordered DuPont company to offer alternative drinking water or treatment for public or private water users living near DuPont's Washington Works plant in West Virginia (and in Ohio), if the level of PFOA detected in drinking water is equal to or greater than 0.50 parts per billion (ppb). This greatly lowered action level replaced the previous 150 ppb threshhold that was established in March 2002. Read more.
Recently, PFOA was found in German drinking water samples in concentrations of up to 500 ng/L.[1]
On a recent episode of the Australian TV show "What's Good For You?" it was established that at heats over 260 degrees Celsius the Teflon coating on frying pans can start to break down, potentially leaking into food. However, such heats levels aren't reached under normal cooking conditions.[2]
[edit] See also
[edit] External links
- [5] Details of PFOA chemistry
- [6] US Environmental Protection Agency - PFOAs
- [7] The Environmental Working Group, PFC page
- [8] Chemical in Teflon, other goods is turning up in disturbing places, Seattle Times Oct 1, 2004
- [9] DuPont, Now in the Frying Pan, NY Times Aug 8, 2004
- [10] US Environmental Protection Agency, PFOA Stewardship Program, Jan 25, 2006
- Perfluorooctanoic Acid (PFOA) by Richard Clapp, a case study at DefendingScience.org
[edit] References
- ^ ES&T Science News (2006): Perfluorinated surfactants contaminate German waters – Mislabeled waste in fertilizer leads to a water scandal. [1]
- ^ DuPont: PFOA – Product Safety
- Farkas, Brian (Associated Press). "Plant tests thousands for exposure to Teflon chemical". Austin American-Statesman (November 18, 2005), p A27.
- Hekster, FM, de Voogt, P, Laane, RWPM, Peijnenburg, J, 2002, Perfluoroalkylated substances: an aquatic environmental assessment, [11]
- "DuPont reaches $16.5M deal with EPA". CNNMoney. Retrieved Dec. 15, 2005.
- Michael Janofsky, "E.P.A. seeks to phase out a toxic chemical," New York Times, Jan 26, 2006
- Martin, J.W.; Smithwick, M.M.; Braune, B.M.; Hoekstra, P.F.; Muir, D.C.G.; Mabury, S.A. "Identification of Long-Chain Perfluorinated Acids in Biota from the Canadian Arctic." Environmental Science and Technology 2004, 38 (2), pp. 373-380.
- Ellis, D.A.; Mabury, S.A.; Martin, J.W.; Muir, D.C.G. "Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment." Nature 2001, 412 (6844), pp. 321-324.
- Lau C, Thibodeaux JR, Hanson RG, et al. (2006). "Effects of perfluorooctanoic acid exposure during pregnancy in the mouse". Toxicology Science 90: 510-518.
