GenX

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This article is about the organic chemical. For the open source energy system model, see open energy system models § GenX. For other uses, see GenX (disambiguation).

GenX is a Chemours trademark name for a synthetic, short-chain organofluorine chemical compound, the ammonium salt of hexafluoropropylene oxide dimer acid (HFPO-DA). It can also be used more informally to refer to the group of related fluorochemicals that are used to produce GenX.[1][2] DuPont began the commercial development of GenX in 2009 as a replacement for perfluorooctanoic acid (PFOA, also known as C8).[3]

GenX is one of many synthetic organofluorine compounds collectively known as per- and polyfluoroalkyl substances (PFASs).

Uses

The chemicals are used in products such as food packaging, paints, cleaning products, non-stick coatings, outdoor fabrics and firefighting foam.[4] The chemicals are manufactured by Chemours, a corporate spin-off of DuPont, in Fayetteville, North Carolina.[5]

GenX chemicals are used as replacements for PFOA for manufacturing fluoropolymers such as Teflon,[2][6] the GenX chemicals serve as surfactants and processing aids in the fluoropolymer production process to lower the surface tension allowing the polymer particles to grow larger. The GenX chemicals are then removed from the final polymer by chemical treatment and heating.[7] PFOA and related compounds have been found to be toxic and carcinogenic.[8] However, in lab tests on rats, GenX has been shown to cause many of the same health problems as PFOA.[9][10]

Chemistry

The manufacturing process combines two molecules of hexafluoropropylene oxide (HFPO) to form HFPO-DA. HFDO-DA is converted into its ammonium salt that is the official GenX compound.[3][2]

The chemical process uses 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid (FRD-903) to generate ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (FRD-902) and heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether (E1).[11]

When GenX contacts water, it releases the ammonium group to become HFPO-DA. Because HFPO-DA is a strong acid, it deprotonates into its conjugate base, which can then be detected in the water.[3]

Pollution

In North Carolina, the Chemours Fayetteville plant released GenX compounds into the Cape Fear River, which is a drinking water source for the Wilmington area. A documentary film, The Devil We Know; a fictional dramatization, Dark Waters; and a nonfiction memoir, Exposure: Poisoned Water, Corporate Greed, and One Lawyer's Twenty-Year Battle Against DuPont by Robert Bilott, subsequently publicized the discharges, leading to controversy over possible health effects.[12]

HFPO-DA was first reported to be in the Cape Fear River in 2012[13] and an additional eleven polyfluoroalkyl substances (PFAS) were reported 2014.[14] These results were published as a formal paper in 2015.[15] The following year, North Carolina State University and the EPA jointly published a study demonstrating HFPO-DA and other PFAS were present in the Wilmington-area drinking water sourced from the Cape Fear river.[16]

In September 2017, the North Carolina Department of Environmental Quality (NCDEQ) ordered Chemours to halt discharges of all fluorinated compounds into the river. Following a chemical spill one month later, NCDEQ cited Chemours for violating provisions in its National Pollutant Discharge Elimination System wastewater discharge permit.[17] In November 2017, the Brunswick County Government filed a federal lawsuit alleging that DuPont failed to disclose research regarding potential risks from the chemical.[18]

In spring 2018, Cape Fear River Watch[19] sued Chemours for Clean Water Act violations and sued the NC Dpt of Environmental Quality for inaction.[20] After Cape Fear River Watch's suits were filed, NCDEQ filed a suit against Chemours, the result of all 3 lawsuits culmindated in a consent order.[21] The order signed by all 3 parties requires Chemours drastically reduce PFAS containing water discharges and air emissions, as well as sampling and filtration for well owners with contaminated wells, among other requirements. All materials relative to status of consent order requirements must be published to a public website,https://www.chemours.com/en/about-chemours/global-reach/fayetteville-works/compliance-testing. One requirement under the order was for non-targeted analysis which found 257 "unknown" PFAS being released from Fayetteville Works, (aside from the 100 'known' PFAS which can be quantified.[22] Cape Fear River Watch published[23] that their research of the NC DEQ permit file [24] indicates that the first PFAS byproducts were likely released from Fayetteville Works in 1976 with the production of Nafion which uses HFPO in production (otherwise known as GenX) and creates byproducts termed Nafion Byproducts 1 through 5, some of which have been found in the blood of Cape Fear area residents.[25]

In 2020 Michigan adopted drinking water standards for 5 previously unregulated PFAS compounds including HFPO-DA which has a maximum contaminant level (MCL) of 370 parts per trillion (ppt). Two previously regulated PFAS compounds PFOA and PFOS had their acceptable limits lowered to 8 ppt and 16 ppt respectively.[26][27]

In 2022 Virginia's Roanoke River had become contaminated by GenX at levels reported to be 1.3 million parts per trillion.[28]

Health effects

GenX has been shown to affect the immune system by suppressing the ability of white blood cells to destroy pathogens[at what levels].[29]

Drinking water health advisories

In June 2022 the U.S. Environmental Protection Agency (EPA) published drinking water health advisories, which are non-regulatory technical documents, for GenX and PFBS.[30][31] The lifetime health advisories and health effects support documents assist federal, state, tribal, and local officials and managers of drinking water systems in protecting public health when these chemicals are present in drinking water.

EPA has listed recommended steps that consumers may take to reduce possible exposure to GenX and other PFAS chemicals.[32]

See also

References

  1. ^ "C3 Dimer Acid and PFAS". Chemours. Retrieved 23 January 2020.
  2. ^ a b c Beekman, M.; et al. (2016-12-12). "Evaluation of substances used in the GenX technology by Chemours, Dordrecht" (PDF). National Institute for Public Health and the Environment (RIVM, The Netherlands). Retrieved 2017-07-23.
  3. ^ a b c Hogue, Cheryl (2018-02-12). "What's GenX still doing in the water downstream of a Chemours plant?". American Chemical Society (ACS). Retrieved 2019-08-21.
  4. ^ "Basic Information on PFAS". PFOA, PFOS and Other PFASs. Washington, D.C.: U.S. Environmental Protection Agency (EPA). 2018-02-18.
  5. ^ "GenX Frequently Asked Questions" (PDF). GenX Investigation. Raleigh, NC: North Carolina Department of Environmental Quality (NCDEQ). 2018-02-15.
  6. ^ "What is the difference between PFOA, PFOS and GenX and other replacement PFAS?". PFOA, PFOS and Other PFASs. EPA. 2018-02-18.
  7. ^ "What is GenX? | Get the Facts".
  8. ^ Lau C.; Anitole K.; Hodes C.; Lai D.; Pfahles-Hutchens A.; Seed J. (October 2007). "Perfluoroalkyl acids: a review of monitoring and toxicological findings". Toxicol. Sci. 99 (2): 366–94. doi:10.1093/toxsci/kfm128. PMID 17519394.
  9. ^ Caverly Rae, JM; Craig, Lisa; Stone, Theodore W.; Frame, Steven R.; Buxton, L. William; Kennedy, Gerald L. (2015). "Evaluation of chronic toxicity and carcinogenicity of ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate in Sprague–Dawley rats". Toxicology Reports. 2: 939–949. doi:10.1016/j.toxrep.2015.06.001. PMC 5598527. PMID 28962433.
  10. ^ Lerner, Sharon (2016-03-03). "New Teflon Toxin Causes Cancer in Lab Animals". The Intercept. Retrieved 2018-12-14.
  11. ^ "DuPont GenX Processing Aid for Making Fluoropolymer Resins" (PDF). 2016-02-09. Archived from the original (PDF) on 2018-02-08. Retrieved 2019-08-21.
  12. ^ "N.C. drinking water tainted with chemical byproduct for decades?". CBS News. 2017-06-26.
  13. ^ Strynar, Mark J.; Dagnino, Sonia; Lindstrom, Andrew; Andersen, Eric; Mcmillan, Larry; Thurman, Michael; Ferrer, Imma; Ball, Carol (2012). Identification of novel polyfluorinated compounds in natural waters using accurate mass TOFMS. SETAC. Long Beach, CA – via ResearchGate.
  14. ^ Strynar, Mark J.; McMahen, Rebecca; Liang, Shuang; Dagnino, Sonia; Lindstrom, Andrew; Andersen, Erik; McMillan, Larry; Thurman, Michael; Ferrer, Imma; Ball, Carol (November 9–13, 2014). Determination of perfluoroalkyl ether carboxylic acids (PFECAs) and sulfonic acids (PFESAs) in North Carolina surface water using high resolution mass spectrometry. SETAC. Vancouver, BC – via Researchgate.
  15. ^ McCord, James; Strynar, Mark (2019-05-07). "Identification of Per- and Polyfluoroalkyl Substances in the Cape Fear River by High Resolution Mass Spectrometry and Nontargeted Screening". Environmental Science & Technology. 53 (9): 4717–4727. Bibcode:2019EnST...53.4717M. doi:10.1021/acs.est.8b06017. ISSN 0013-936X. PMC 7478245. PMID 30993978.
  16. ^ Sun, Mei; Arevalo, Elisa; Strynar, Mark; Lindstrom, Andrew; Richardson, Michael; Kearns, Ben; Pickett, Adam; Smith, Chris; Knappe, Detlef R. U. (2016-12-13). "Legacy and Emerging Perfluoroalkyl Substances Are Important Drinking Water Contaminants in the Cape Fear River Watershed of North Carolina". Environmental Science & Technology Letters. 3 (12): 415–419. Bibcode:2016EnSTL...3..415S. doi:10.1021/acs.estlett.6b00398.
  17. ^ "GenX Timeline". NCDEQ. Archived from the original on 2018-12-24. Retrieved 2018-04-22.
  18. ^ Clabby, Catherine (2017-11-02). "Newest GenX Lawsuit Attacks DuPont Science". Chapel Hill, NC: North Carolina Health News.
  19. ^ https://capefearriverwatch.org/genx/
  20. ^ Alder, Cole (2018-05-16). "Cape Fear River Watch to file suit against Chemours". Per- and Polyfluoroalkyl Substances; News. Boston, MA: Northeastern University, Social Science Environmental Health Research Institute.
  21. ^ https://capefearriverwatch.org/genx/
  22. ^ https://www.chemours.com/en/about-chemours/global-reach/fayetteville-works/compliance-testing
  23. ^ https://capefearriverwatch.org/genx/
  24. ^ https://edocs.deq.nc.gov/WaterResources/DocView.aspx?id=611983&dbid=0&repo=WaterResources&searchid=627d7915-27f4-4e8b-beb3-ec53cd75941b
  25. ^ https://genxstudy.ncsu.edu/
  26. ^ Matheny, Keith (3 August 2020). "Michigan's drinking water standards for these chemicals now among toughest in nation". Detroit Free Press. Archived from the original on 31 January 2022. Retrieved 31 March 2022.
  27. ^ "New state drinking water standards pave way for expansion of Michigan's PFAS clean-up efforts". Michigan.gov. 3 August 2020. Archived from the original on 3 January 2022. Retrieved 5 April 2022.
  28. ^ "Source of 'forever chemical' in the Roanoke River traced to Elliston plant". 10 November 2022.
  29. ^ Phelps, Drake W.; Palekar, Anika I.; Conley, Haleigh E.; Ferrero, Giuliano; Driggers, Jacob H.; Linder, Keith E.; Kullman, Seth W.; Reif, David M.; Sheats, M. Katie; DeWitt, Jamie C.; Yoder, Jeffrey A. (2023-12-31). "Legacy and emerging per- and polyfluoroalkyl substances suppress the neutrophil respiratory burst". Journal of Immunotoxicology. 20 (1): 2176953. doi:10.1080/1547691X.2023.2176953. ISSN 1547-691X. PMC 10361455. PMID 36788734. S2CID 256870330.
  30. ^ "EPA Announces New Drinking Water Health Advisories for PFAS Chemicals, $1 Billion in Bipartisan Infrastructure Law Funding to Strengthen Health Protections". EPA. 2022-06-15. News release.
  31. ^ "Drinking Water Health Advisories". EPA. 2022-06-15.
  32. ^ "Meaningful and Achievable Steps You Can Take to Reduce Your Risk". PFOA, PFOS and Other PFAS. EPA. 2022-08-18.
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