Chemistry:GenX

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Short description: Trademark name for a synthetic, organofluorine chemical compound


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 sued Chemours for numerous Clean Water Act violations.[19] Meanwhile, traces of GenX were found in control wells surrounding a Miteni, SA plant in Trissino, Italy that had reprocessed Chemours fluoroether waste. The resulting regulatory furor drove Miteni into bankruptcy.[20]

That fall, NCDEQ filed a draft consent order concluding its GenX investigation. The order would require Chemours to reduce air pollution emissions and water pollution discharges of GenX and other chemicals, and would levy a $13-million civil penalty.[21] In February 2019 a North Carolina Superior Court judge ordered Chemours to monitor GenX air emissions, analyze PFAS in river sediment and provide drinking water filtration systems.[22]

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.[23][24]

In 2022 Virginia's Roanoke River had become contaminated by GenX at levels reported to be 1.3 million parts per trillion.[25]

Health effects

GenX has been shown to affect the immune system by suppressing the ability of white blood cells to destroy pathogens.[26]

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.[27][28] 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.[29]

See also

  • Perfluorinated alkylated substances (PFAS)
  • Timeline of events related to per- and polyfluoroalkyl substances (PFAS)

References

  1. ↑ "C3 Dimer Acid and PFAS". Chemours. https://www.chemours.com/en/about-chemours/global-reach/fayetteville-works/fayetteville-works-toxicology. 
  2. ↑ 2.0 2.1 2.2 Beekman, M.; Zweers, P. (2016-12-12). "Evaluation of substances used in the GenX technology by Chemours, Dordrecht". National Institute for Public Health and the Environment (RIVM, The Netherlands). https://www.rivm.nl/bibliotheek/rapporten/2016-0174.pdf. 
  3. ↑ 3.0 3.1 3.2 Hogue, Cheryl (2018-02-12). "What's GenX still doing in the water downstream of a Chemours plant?". American Chemical Society (ACS). https://cen.acs.org/articles/96/i7/whats-genx-still-doing-in-the-water-downstream-of-a-chemours-plant.html. 
  4. ↑ "Basic Information on PFAS". Washington, D.C.: U.S. Environmental Protection Agency (EPA). 2018-02-18. https://www.epa.gov/pfas/basic-information-pfas. 
  5. ↑ "GenX Frequently Asked Questions". Raleigh, NC: North Carolina Department of Environmental Quality (NCDEQ). 2018-02-15. https://files.nc.gov/ncdeq/GenX/SAB/FAQ_updated_021518.pdf. 
  6. ↑ "What is the difference between PFOA, PFOS and GenX and other replacement PFAS?". EPA. 2018-02-18. https://www.epa.gov/pfas/basic-information-pfas#difference. 
  7. ↑ "What is GenX? | Get the Facts". https://www.chemours.com/en/about-chemours/genx. 
  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. PMID 28962433. 
  10. ↑ Lerner, Sharon (2016-03-03). "New Teflon Toxin Causes Cancer in Lab Animals" (in en-US). https://theintercept.com/2016/03/03/new-teflon-toxin-causes-cancer-in-lab-animals/. 
  11. ↑ "DuPont GenX Processing Aid for Making Fluoropolymer Resins". 2016-02-09. https://www.ozhz.nl/fileadmin/user_upload/2016-02-09_Brief_gedeputeerde_Janssen_en_beantwoording_vragen_BenW_Sliedrecht_over_historische_PFOA-emissies_Chemours_voorheen_Dupont_de_Nemours_bijlagen__nazending_2_.pdf. 
  12. ↑ "N.C. drinking water tainted with chemical byproduct for decades?". CBS News. 2017-06-26. https://www.cbsnews.com/news/wilmington-nc-cape-fear-river-water-tainted-genx-dupont-chemours/. 
  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. https://www.researchgate.net/publication/358128921. 
  14. ↑ Strynar, Mark J.; McMahen, Rebecca; Liang, Shuang; Dagnino, Sonia; Lindstrom, Andrew; Andersen, Erik; McMillan, Larry; Thurman, Michael et al. (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. https://www.researchgate.net/publication/358128738. 
  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. doi:10.1021/acs.est.8b06017. ISSN 0013-936X. PMID 30993978. Bibcode: 2019EnST...53.4717M. 
  16. ↑ Sun, Mei; Arevalo, Elisa; Strynar, Mark; Lindstrom, Andrew; Richardson, Michael; Kearns, Ben; Pickett, Adam; Smith, Chris et al. (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. doi:10.1021/acs.estlett.6b00398. Bibcode: 2016EnSTL...3..415S. 
  17. ↑ "GenX Timeline". NCDEQ. https://deq.nc.gov/news/hot-topics/genx-investigation/genx-timeline. 
  18. ↑ Clabby, Catherine (2017-11-02). "Newest GenX Lawsuit Attacks DuPont Science". Chapel Hill, NC: North Carolina Health News. https://www.northcarolinahealthnews.org/2017/11/02/newest-genx-lawsuit-attacks-dupont-science/. 
  19. ↑ Alder, Cole (2018-05-16). "Cape Fear River Watch to file suit against Chemours". Boston, MA: Northeastern University, Social Science Environmental Health Research Institute. https://pfasproject.com/2018/05/16/cape-fear-river-watch-to-file-suit-against-chemours/. 
  20. ↑ Hogue, Cheryl (3 March 2019). "Imports of used PFAS into US scrutinized". Chemical & Engineering News (American Chemical Society) 97 (9). https://cen.acs.org/environment/persistent-pollutants/Imports-used-PFAS-US-scrutinized/97/i9. 
  21. ↑ "Consert Order (draft): North Carolina Department of Environmental Quality v. The Chemours Company". NCDEQ. 2018-11-21. https://files.nc.gov/ncdeq/GenX/Consent-order-11212018.pdf. 
  22. ↑ "Court approves order to stop PFAS from entering Cape Fear River". Wilmington, NC: WECT News. 2019-02-26. https://www.wect.com/2019/02/25/court-approves-order-stop-pfas-entering-cape-fear-river/. 
  23. ↑ Matheny, Keith (3 August 2020). "Michigan's drinking water standards for these chemicals now among toughest in nation". https://www.freep.com/story/news/local/michigan/2020/08/03/tougher-pfas-standards-drinking-water-michigan/5574268002/. 
  24. ↑ "New state drinking water standards pave way for expansion of Michigan's PFAS clean-up efforts". 3 August 2020. https://www.michigan.gov/egle/0,9429,7-135--535602--,00.html. 
  25. ↑ "Source of 'forever chemical' in the Roanoke River traced to Elliston plant". 10 November 2022. https://roanoke.com/news/local/source-of-forever-chemical-in-the-roanoke-river-traced-to-elliston-plant/article_e7953262-613e-11ed-baad-bb83787f5da8.html. 
  26. ↑ Phelps, Drake W.; Palekar, Anika I.; Conley, Haleigh E.; Ferrero, Giuliano; Driggers, Jacob H.; Linder, Keith E.; Kullman, Seth W.; Reif, David M. et al. (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. PMID 36788734. 
  27. ↑ "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. https://www.epa.gov/newsreleases/epa-announces-new-drinking-water-health-advisories-pfas-chemicals-1-billion-bipartisan. 
  28. ↑ "Drinking Water Health Advisories". EPA. 2022-06-15. https://www.epa.gov/sdwa/drinking-water-health-advisories-has. 
  29. ↑ "Meaningful and Achievable Steps You Can Take to Reduce Your Risk". EPA. 2022-08-18. https://www.epa.gov/pfas/meaningful-and-achievable-steps-you-can-take-reduce-your-risk. 



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