Politetrafluoretileno: diferenças entre revisões
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Etiqueta: Inserção de predefinição obsoleta |
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Linha 31:
A fórmula química do [[monômero]], o [[tetrafluoretileno]], é 2FC=CF2, e o polímero -(2FC-CF2)<sub>n</sub>-
A marca
A principal virtude deste material é que é uma substância praticamente inerte, não [[reação química|reage]] com outras substâncias químicas, exceto em situações muito especiais. Isto se deve basicamente
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==História ==
3M (then Minnesota Mining and Manufacturing Company) began producing PFOA by [[electrochemical fluorination]] in 1947.<ref name=Prevedouros2006>{{cite journal |vauthors=Prevedouros K, Cousins IT, Buck RC, Korzeniowski SH | title =Sources, fate and transport of perfluorocarboxylates |journal=Environ. Sci. Technol. |volume=40 |issue=1 |pages=32–44 |date=January 2006 |doi =10.1021/es0512475 |pmid=16433330}}</ref> Starting in 1951, DuPont purchased PFOA from 3M for use in the manufacturing of specific [[fluoropolymers]]—commercially branded as Teflon, but DuPont internally referred to the material as C8.<ref name="NYT_jan_2016" /><ref name=Emmett2006>{{cite journal |vauthors=Emmett EA, Shofer FS, Zhang H, Freeman D, Desai C, Shaw LM | title =Community exposure to perfluorooctanoate: relationships between serum concentrations and exposure sources |journal=J. Occup. Environ. Med. |volume=48 |issue=8 |pages=759–70 |date=August 2006 |pmid=16902368 |pmc=3038253 |doi=10.1097/01.jom.0000232486.07658.74}}</ref>
In the fall of 2000, lawyer Rob Bilott, a partner at Taft Stettinius & Hollister, won a court order forcing DuPont to share all documentation related to PFOA. This included 110,000 files, consisting of confidential studies and reports conducted by DuPont scientists over decades. By 1993, DuPont understood that "PFOA caused cancerous testicular, pancreatic and liver tumors in lab animals" and the company began to investigate alternatives. However, products manufactured with PFOA were such an integral part of DuPont's earnings, $1 billion in annual profit, they chose to continue using PFOA.<ref name="NYT_jan_2016">{{cite news | url=https://www.nytimes.com/2016/01/10/magazine/the-lawyer-who-became-duponts-worst-nightmare.html?_r=0 |title=The Lawyer Who Became DuPont’s Worst Nightmare |date=6 January 2016 |accessdate=8 January 2016 |author=Rich, Nathaniel |work=New York Times}}</ref> Billott learned that both "3M and DuPont had been conducting secret medical studies on PFOA for more than four decades", and by 1961 DuPont was aware of [[hepatomegaly]] in mice fed with PFOA.<ref name="NYT_jan_2016" /><ref>{{cite conference |first=Gerald J. |last=Arneson |title=Toxicity of Teflon Dispersing Agents |publisher=DuPont, Polychemicals Department, Research & Development Division, Experimental Station |date=November 1961 |url=http://www.defendingscience.org/case_studies/upload/1961-memo.pdf |accessdate=2008-09-21}}</ref><ref name=Clapp>{{cite web |url=http://www.defendingscience.org/case_studies/perfluorooctanoic-acid.cfm |title=Case Studies in Science Policy: Perfluorooctanoic Acid |accessdate=2008-12-19 |last=Clapp |first=Richard |author2=Polly Hoppin |author3=Jyotsna Jagai |author4=Sara Donahue |publisher=Project on Scientific Knowledge and Public Policy (SKAPP) |deadurl=yes |archiveurl=https://web.archive.org/web/20090301012304/http://www.defendingscience.org/case_studies/perfluorooctanoic-acid.cfm |archivedate=2009-03-01 |df= }}</ref>
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 [[Perfluorooctanesulfonic acid|PFOS]].<ref name=Kennedy2004>{{cite journal |vauthors=Kennedy GL, Butenhoff JL, Olsen GW, etal | title =The toxicology of perfluorooctanoate |journal=Crit. Rev. Toxicol. |volume=34 |issue=4 |pages=351–84 |year=2004 |pmid =15328768 |doi=10.1080/10408440490464705}}</ref><ref>{{cite journal |vauthors=Giesy JP, Kannan K |title=Perfluorochemical surfactants in the environment |journal =Environ. Sci. Technol. |volume=36 |issue=7 |pages=146A–152A |date=April 2002 |pmid =11999053 |doi=10.1021/es022253t |url=}}</ref><ref name=Lau04>{{cite journal |vauthors=Lau C, Butenhoff JL, Rogers JM |title=The developmental toxicity of perfluoroalkyl acids and their derivatives |journal=Toxicol. Appl. Pharmacol.
|volume =198 |issue=2 |pages=231–41 |date=July 2004 |pmid =15236955 |doi=10.1016/j.taap.2003.11.031 |url=}}</ref>
Bilott exposed how DuPont had been knowingly polluting water with PFOAs in [[Parkersburg, West Virginia]] since the 1980s.<ref name="NYT_jan_2016" /> In the 1980s and 1990s, researchers investigated the [[toxicity]] of PFOA.<ref name=Clapp />
In 1999, EPA ordered companies to examine the effects of perfluorinated chemicals after receiving data on the global distribution and toxicity of PFOS.<ref>{{cite journal |last=Ullah |first=Aziz |title=The Fluorochemical Dilemma: What the PFOS/PFOA fuss is all about |journal=Cleaning & Restoration |date=October 2006 |url=https://www.restorationindustry.org/buyersguide/FlurochemicalsOct06.pdf |accessdate=2008-09-24}}</ref> For these reasons, and EPA pressure,<ref>{{cite news |first=Jennifer 8. |last=Lee |authorlink=Jennifer 8. Lee |title =E.P.A. Orders Companies to Examine Effects of Chemicals |work =The New York Times |date=15 April 2003 |accessdate=15 May 2009 |url=https://www.nytimes.com/2003/04/15/science/epa-orders-companies-to-examine-effects-of-chemicals.html?pagewanted=2}}</ref> in May 2000, 3M announced the phaseout of the production of PFOA, PFOS, and PFOS-related products—the company's best-selling repellent.<ref name=3M08>{{cite web |url=http://solutions.3m.com/wps/portal/3M/en_US/PFOS/PFOA/Information/Action |title=3M United States: PFOS PFOA: What is 3M Doing? |publisher=3M Company |accessdate=2009-01-05 |deadurl=yes |archiveurl=https://web.archive.org/web/20141210020455/http://solutions.3m.com/wps/portal/3M/en_US/PFOS/PFOA/Information/Action |archivedate=2014-12-10 |df= }}</ref> 3M stated that they would have made the same decision regardless of EPA pressure.<ref>{{cite journal |last=Weber |first=Joseph |title=3M's Big Cleanup – Why it decided to pull the plug on its best-selling stain repellent |journal=Business Week |issue=3684 |page=96 |date=2000-06-05}}</ref>
Because of the 3M phaseout, in 2002, DuPont built its own plant in [[Fayetteville, North Carolina]] to manufacture the chemical.<ref name=china>{{cite news |first=Ken |last=Ward, Jr. |title=DuPont finds high C8 in Chinese workers |work=The Charleston Gazette |date=7 November 2008 |accessdate=6 January 2009 |url=http://sundaygazettemail.com/News/200811060596?page=1&build=cache |archive-url=https://web.archive.org/web/20090224111523/http://sundaygazettemail.com/News/200811060596?page=1&build=cache |archive-date=2009-02-24 |dead-url=yes |df= }}</ref> The chemical has received attention due to litigation from the PFOA-contaminated community around DuPont's Washington Works facility in [[Washington, West Virginia]], along with EPA focus. Research on PFOA has demonstrated ubiquity, animal-based toxicity, and some associations with human health parameters and potential health effects. Additionally, advances in [[analytical chemistry]] in recent years have allowed the routine detection of low- and sub-[[parts per billion]] levels of PFOA in a variety of substances.<ref name=Lau04 /> In 2013, [[Gore-Tex]] eliminated the use of PFOAs in the manufacture of its weatherproof functional fabrics.<ref>{{cite web |url=http://news.gorefabrics.com/en_gb/enterprise/innovation/gore-completes-elimination-of-pfoa-from-raw-material-of-its-functional-fabrics/|title=GORE completes elimination of PFOA from raw material of its functional fabrics: GORE-TEX Products Newsroom |publisher=Gore Fabrics |accessdate=13 August 2015}}</ref> [[GenX]] has been introduced as a replacement for PFOA, but in a 2015 study which tested the effects on rats, GenX caused many of the same health problems as PFOA.<ref>{{cite journal |last1=Caverly Rae |first1=JM |last2=Craig |first2=Lisa |last3=Stone |first3=Theodore W. |last4=Frame |first4=Steven R. |last5=Buxton |first5=L. William |last6=Kennedy |first6=Gerald L. |title=Evaluation of chronic toxicity and carcinogenicity of ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate in Sprague–Dawley rats |url=https://www.sciencedirect.com/science/article/pii/S221475001530010X |date=2015 |journal=Toxicology Reports |volume=2 |pages=939-949 |doi=10.1016/j.toxrep.2015.06.001}}</ref>
For his work in the exposure of the contamination, lawyer Rob Bilott received [[The Right Livelihood Award]] in 2017.<ref>{{cite web |url=http://www.rightlivelihoodaward.org/laureates/robert-bilott/ |title=Robert Bilott, The Right Livelihood Award|publisher=The Right Livelihood Award |accessdate=24 January 2018}}</ref> This battle with DuPont is featured in the documentary called [[The Devil We Know (film)|The Devil We Know]], which premiered at the [[Sundance Film Festival]] in 2018.<ref>{{cite web |url=https://www.democracynow.org/2018/1/23/dupont_vs_the_world_chemical_giant |title=DuPont vs. the World: Chemical Giant Covered Up Health Risks of Teflon Contamination Across Globe |publisher=Democracy Now! |accessdate=24 January 2018}}</ref> -->
== Riscos à saúde ==
Em 2005, o governo dos EUA advertiu que a exposição a baixos níveis de uma substância química utilizada na fabricação do Teflon® pode causar riscos para a saúde.
Segundo um relatório preliminar da [[Agência de Proteção Ambiental dos Estados Unidos]] (EPA), o [[ácido perfluoro-octanoico]], conhecido como [[PFOA]] - material isolante muito resistente ao calor e à corrosão, utilizado em utensílios de cozinha - pode ter efeitos nocivos à saude humana. O relatório baseou-se em testes feitos em animais e concluiu haver provas de que a substância provoca câncer nos ratos de laboratório. Ainda segundo o relatório, a substância provavelmente causa danos ao fígado e também estava presente no leite materno dos ratos que o ingeriram nos laboratórios. Além disso, o PFOA teria potencial de elevar os níveis de [[colesterol]] e os [[triglicéridos]] no [[sangue]]. Essa possibilidade já havia sido levantada por um estudo divulgado pela multinacional química [[Dupont]]. A empresa, no entanto, ressaltou que não encontrou provas de que a substância cause problemas para a saúde em geral.<ref>[http://noticias.terra.com.br/ciencia/noticias/0,,OI453547-EI298,00-Substancia+do+teflon+pode+fazer+mal+a+saude.html Substância do teflon pode fazer mal à saúde.] ''Terra'', 12 de janeiro de 2005.</ref>
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