Fluorosurfactant

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Skeletal structure of PFOS, an effective and bioaccumulative fluorosurfactant
Space filling model of PFOS

Fluorosurfactants (also fluorinated surfactants, perfluorinated alkylated substances or PFASs, or Forever Chemicals) are synthetic organofluorine chemical compounds that have multiple fluorine atoms. They can be polyfluorinated or fluorocarbon-based (perfluorinated).[1] As surfactants, they are more effective at lowering the surface tension of water than comparable hydrocarbon surfactants. They have a fluorinated "tail" and a hydrophilic "head." Some human-made fluorosurfactants, such as PFOS and PFOA, are persistent organic pollutants and are detected in humans and wildlife.[2]

Physical and chemical properties[edit]

A shiny spherical drop of water on blue cloth
Fluorine-containing durable water repellent makes a fabric water-resistant.

Fluorosurfactants can lower the surface tension of water down to a value half of what is attainable by using hydrocarbon surfactants.[3] This ability is due to the lipophobic nature of fluorocarbons, as fluorosurfactants tend to concentrate at the liquid-air interface.[4] They are not as susceptible to the London dispersion force, a factor contributing to lipophilicity, because the electronegativity of fluorine reduces the polarizability of the surfactants' fluorinated molecular surface. Therefore, the attractive interactions resulting from the "fleeting dipoles" are reduced, in comparison to hydrocarbon surfactants. Fluorosurfactants are more stable and fit for harsh conditions than hydrocarbon surfactants because of the stability of the carbon–fluorine bond. Likewise, perfluorinated surfactants persist in the environment for that reason.[2]

Economic role[edit]

Fluorosurfactants play a key economic role for companies such as DuPont, 3M, and W. L. Gore & Associates because they are used in emulsion polymerization to produce fluoropolymers. Fluorosurfactants have two main markets: a $1 billion annual market for use in stain repellents, and a $100 million annual market for use in polishes, paints, and coatings.[5]

Health and environmental concerns[edit]

Fluorosurfactants such as perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) have caught the attention of regulatory agencies because of their persistence, toxicity, and widespread occurrence in the blood of general populations[6][7] and wildlife. In 2009 PFASs were listed as persistent organic pollutants under the Stockholm Convention, due to their ubiquitous, persistent, bioaccumulative, and toxic nature.[8][9] Their production has been regulated or phased out by manufacturers, such as 3M, DuPont, Daikin, and Miteni in the USA, Japan, and Europe.

Some manufacturers have now[when?] replaced PFOS and PFOA with short-chain PFASs, such as perfluorohexanoic acid (PFHxA), perfluorobutanesulfonic acid[5] and perfluorobutane sulfonate (PFBS). Shorter fluorosurfactants may be less prone to accumulating in mammals;[5] there is still concern that they may be harmful to both humans,[10][11][12] and the environment at large.[13]

In 2017, the ABC's current affairs programme Four Corners reported that the storage and use of firefighting foams containing perfluorinated surfactants at Australian Defence Force facilities around Australia had contaminated nearby water resources.[14]

United States[edit]

Certain PFAS chemicals are no longer manufactured in the United States as a result of phase outs including the PFOA Stewardship Program,[15] in which eight major chemical manufacturers agreed to eliminate the use of PFOA and PFOA-related chemicals in their products and as emissions from their facilities. Although PFOA and PFOS are no longer manufactured in the United States, they are still produced internationally and can be imported into the United States in consumer goods such as carpet, leather and apparel, textiles, paper and packaging, coatings, rubber and plastics.[16] There are an estimated 26,000 PFAS-contaminated sites across the United States, and scientists have estimated that at least six million Americans have PFAS-contaminated drinking water above the existing safe limits set by the U.S. EPA.[17][18]

Michigan[edit]

Launched in 2017, the Michigan PFAS Action Response Team (MPART) is the first multi-agency action team of its kind in the nation. Agencies representing health, environment and other branches of state government have joined together to investigate sources and locations of PFAS contamination in the state, take action to protect people’s drinking water, and keep the public informed.[19]

Groundwater is tested at locations throughout the state by various parties to ensure safety, compliance with regulations, and to proactively detect and remedy potential problems. In 2010, the Michigan Department of Environmental Quality (MDEQ) discovered levels of Per- and Polyfluoroalkyl Substances (PFAS) in groundwater monitoring wells at the former Wurtsmith Air Force Base. As additional information became available from other national testing, Michigan expanded its investigations into other locations where PFAS compounds were potentially used.[19]

In 2018, the MDEQ's Remediation and Redevelopment Division (RRD) established cleanup criteria for groundwater used as drinking water of 70 ppt of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), individually or combined. The RRD staff are responsible for implementing these criteria as part of their ongoing efforts to clean-up sites of environmental contamination. The RRD staff are the lead investigators at most of the PFAS sites on the MPART website and also conduct interim response activities, such as coordinating bottled water or filter installations with local health departments at sites under investigation or with known PFAS concerns. Most of the groundwater sampling at PFAS sites under RRD’s lead is conducted by contractors familiar with PFAS sampling techniques. The RRD also has a Geologic Services Unit, with staff who install monitoring wells and are also well versed with PFAS sampling techniques.[19]

The MDEQ has been conducting environmental clean-up of regulated contaminants for decades. Due to the evolving nature of PFAS regulations as new science becomes available, the RRD is evaluating the need for regular PFAS sampling at Superfund sites and is including an evaluation of PFAS sampling needs as part of a Baseline Environmental Assessment review.[19]

Earlier this year, the RRD purchased lab equipment that will allow the MDEQ Environmental Lab to conduct analyses of certain PFAS samples. (Currently, most samples are shipped to one of the few labs in the country that conduct PFAS analysis, in California, although private labs in other parts of the country, including Michigan, are starting to offer these services.) As of August 2018, RRD has hired additional staff to work on developing the methodology and conducting PFAS analyses.[19]

Forever chemicals[edit]

PFAS chemicals were re-branded as "Forever Chemicals" in a 2018 op-ed.[20] The nickname was derived by combining the two dominant attributes of this class of chemicals: 1) PFAS chemicals are characterized by a carbon-fluorine (C-F) backbone (the "F-C" in "Forever Chemicals"); and 2) the carbon fluorine bond is one of the strongest bonds in organic chemistry, which gives these chemicals an extremely long environmental half-life (the "Forever" in "Forever Chemicals").

The Forever Chemicals name is now commonly used in media outlets in addition to the more technical name of per- and polyflourinated alkyl substances, or PFAS.[21][22] [23]

Remediation solutions[edit]

Liquids treatment[edit]

Several technologies are currently available for remediating PFAS in liquids. These technologies can be applied to drinking water supplies, groundwater, industrial wastewater, surface water, and other miscellaneous applications (such as landfill leachate). Influent concentrations of PFAS can vary by orders of magnitude for specific media or applications. These influent values, along with other general water quality parameters (for example, pH) can influence the performance and operating costs for the treatment technologies.[24]

  • Sorbtion
  • Granular activated carbon
  • Biochar
  • Ion exchange
  • Precipitation/flocculation/coagulation
  • Redox manipulation
  • Membrane filtration
  • Reverse osmosis
  • Nanofiltration[24]

Private and public sector applications of one or more of these methodologies above is being applied to remediation sites throughout the United States and other international locations.[25][26][27] Most solutions involve on-site treatment systems, while others are leveraging off-site infrastructure and facilities - such as a centralized industrial wastewater treatment facility - to treat and dispose of the PFAS pool of compounds.

Theoretical and early stage solutions[edit]

The MSU-Fraunhofer team has a viable solution to treat PFAS-contaminated wastewater that’s ready for a pilot-scale investigation. The electrochemical oxidation system uses boron-doped diamond electrodes. The process breaks down the contaminants’ formidable molecular bonds, cleaning the water while systematically destroying the hazardous compounds.[28]

“EO, or electrochemical oxidation, is a simple, clean and effective method for destruction of PFAS and other co-contaminants as a complementary procedure to other wastewater treatment processes,” said Cory Rusinek, electrochemist at MSU-Fraunhofer. “If we can remove it from wastewater, we can reduce its occurrence in surface waters.”[28]

Class action lawsuits[edit]

In October 2018, a class action suit was filed by an Ohio firefighter against several producers of fluorosurfactants, including 3M and DuPont, on behalf of all US residents who may have adverse health effects from exposure to PFAS chemicals.[29] Five New Jersey companies were declared to be financially responsible for statewide remediation of the chemicals in a directive from the New Jersey Department of Environmental Protection in March 2019.[30]

In February 2017, DuPont and Chemours agreed to pay $671 million to settle lawsuits arising from 3,550 personal injury claims related to releasing of PFAS chemicals from their Parkersburg, WV, into the drinking water of several thousand residents.[31] This was after a court-created independent scientific panel, "The C8 Science Panel", found a 'probable link' between C8 exposure and six illnesses: kidney and testicular cancer, ulcerative colitis, thyroid disease, pregnancy-induced hypertension and high cholesterol.[32]

In February 2018, 3M settled a lawsuit for $850 million related to contaminated drinking water in Minnesota.[33]

Examples[edit]

References[edit]

  1. ^ Lehmler HJ (March 2005). "Synthesis of environmentally relevant fluorinated surfactants--a review". Chemosphere. 58 (11): 1471–96. Bibcode:2005Chmsp..58.1471L. doi:10.1016/j.chemosphere.2004.11.078. PMID 15694468.
  2. ^ a b Houde M, Martin JW, Letcher RJ, Solomon KR, Muir DC (June 2006). "Biological monitoring of polyfluoroalkyl substances: A review". Environmental Science & Technology. 40 (11): 3463–73. Bibcode:2006EnST...40.3463H. doi:10.1021/es052580b. PMID 16786681. Supporting Information (PDF).
  3. ^ Salager J (2002). "Surfactants-Types and Uses" (PDF). FIRP Booklet # 300-A. Universidad de los Andes Laboratory of Formulation, Interfaces Rheology, and Processes: 45. Retrieved 7 September 2008.
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  5. ^ a b c Renner R (January 2006). "The long and the short of perfluorinated replacements". Environmental Science & Technology. 40 (1): 12–3. Bibcode:2006EnST...40...12R. doi:10.1021/es062612a. PMID 16433328.
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  7. ^ Wang Z, Cousins IT, Berger U, Hungerbühler K, Scheringer M (2016). "Comparative assessment of the environmental hazards of and exposure to perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs): Current knowledge, gaps, challenges and research needs". Environment International. 89-90: 235–47. doi:10.1016/j.envint.2016.01.023. PMID 26922149.
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  9. ^ "Stockholm Convention Clearing". chm.pops.int. Secretariat of the Stockholm Convention. Retrieved 26 October 2016.
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  11. ^ Birnbaum LS, Grandjean P (May 2015). "Alternatives to PFASs: perspectives on the science". Environmental Health Perspectives. 123 (5): A104–5. doi:10.1289/ehp.1509944. PMC 4421778. PMID 25932670.
  12. ^ Perry MJ, Nguyen GN, Porter ND (2016). "The Current Epidemiologic Evidence on Exposures to Poly- and Perfluoroalkyl Substances (PFASs) and Male Reproductive Health". Current Epidemiology Reports. 3 (1): 19–26. doi:10.1007/s40471-016-0071-y. ISSN 2196-2995.
  13. ^ Scheringer M, Trier X, Cousins IT, de Voogt P, Fletcher T, Wang Z, Webster TF (November 2014). "Helsingør statement on poly- and perfluorinated alkyl substances (PFASs)". Chemosphere. 114: 337–9. Bibcode:2014Chmsp.114..337S. doi:10.1016/j.chemosphere.2014.05.044. PMID 24938172.
  14. ^ "'Shocked and disgusted' Katherine residents demand action on PFAS contamination". ABC News. 2017-10-10. Retrieved 2017-10-10.
  15. ^ "Fact Sheet: 2010/2015 PFOA Stewardship Program". OSCSSP. US EPA. 2016-05-10. Retrieved 2018-12-18.
  16. ^ "Basic Information on PFAS". OA US EPA. US EPA. 2016-03-30. Retrieved 2018-12-18.
  17. ^ Timmis A (January 2018). "Using Dredged Materials to Improve a Salt Marsh". The Military Engineer. 110 (712): 61.
  18. ^ Hu XC, Andrews DQ, Lindstrom AB, Bruton TA, Schaider LA, Grandjean P, et al. (October 2016). "Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants". Environmental Science & Technology Letters. 3 (10): 344–350. doi:10.1021/acs.estlett.6b00260. PMC 5062567. PMID 27752509.
  19. ^ a b c d e "PFAS Response - PFAS Response". www.michigan.gov. Retrieved 2018-12-18.
  20. ^ "Opinion | These toxic chemicals are everywhere — even in your body. And they won't ever go away". Washington Post. Retrieved 2019-06-08.
  21. ^ Turkewitz J (2019-02-22). "Toxic 'Forever Chemicals' in Drinking Water Leave Military Families Reeling". The New York Times. ISSN 0362-4331. Retrieved 2019-06-08.
  22. ^ Kounang N. "FDA confirms PFAS chemicals are in the US food supply". CNN. Retrieved 2019-06-08.
  23. ^ "Critics say EPA action plan on toxic 'forever chemicals' falls short". The Washington Post. February 14, 2019.
  24. ^ a b "Remediation Technologies and Methods for Per- and Polyfluoroalkyl Substances (PFAS)" (PDF). Interstate Technology & Regulatory Council (ITRC). Retrieved 2018-12-18.
  25. ^ "PFAS Response Team | Strength Environmental". Strength Environmental. Retrieved 2018-12-18.
  26. ^ "PFAS Remediatio n". Clean Harbors Remediation Technologies - Remediation Equipment. Retrieved 2018-12-18.
  27. ^ "PFAS Assessment & Mitigation". www.battelle.org. Retrieved 2018-12-18.
  28. ^ a b "Diamond technology cleans up PFAS-contaminated wastewater". MSUToday. Retrieved 2018-12-18.
  29. ^ Sharon Lerner (October 6, 2018). "Nationwide class action lawsuit targets Dupont, Chemours, 3M, and other makers of PFAS chemicals". The Intercept. Retrieved October 8, 2018.
  30. ^ https://www.nj.com/news/2019/05/state-ordered-chemical-companies-to-pay-for-pollution-clean-up-they-say-no-way.html
  31. ^ "DuPont settles lawsuits over leak of chemical used to make Teflon". Reuters. 2017-02-13. Retrieved 2019-06-08.
  32. ^ "C8 Science Panel Website". www.c8sciencepanel.org. Retrieved 2019-06-08.
  33. ^ "3M Settles Minnesota Lawsuit for $850 Million". 2019-06-07. Retrieved 2019-06-08.

Further reading[edit]