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Teflon - out of the frying pan ...

Perfluoro-octanoic acid (PFOA), also known as ‘C-8’, is a suspected carcinogen now found in humans, other animals and plants in the US, Europe and Asia. PFOA is very persistent. Released into the environment it looks as if it will take literally millions of years to biodegrade. The company ‘3M’ (which once manufactured PFOA) found that it took 4.4 years for just half of it to be excreted from workers’ bodies.

Where does it come from?
PFOA, a member of the perfluorochemical (PFC) family, is an essential ingredient of Teflon, the non-stick coating used in cookware. Some is released during manufacture, but it is thought that the majority is given off when the non-stick pans and trays are heated to normal cooking temperatures and, of course, when allowed to overheat or burn dry in error. The average levels of PFOA (now found in 96% of Americans) are fivefold higher than can be attributed to releases from the chimneys of chemical company DuPont’s Teflon factories.

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The latest DuPont studies show that the Teflon emits toxic particulates at 446°F, but the lowest temperature linked to emissions by an independent study is 325°Fahrenheit (F).[1] (This is the temperature reached by a Teflon-lined oven when baking biscuits.) In one case where this occurred, all the baby parrots in a cage in the owner’s kitchen died. DuPont does warn that fumes from non-stick cookware can be fatal for birds but, despite even its own evidence (see below), continues to deny that any emissions occur below temperatures well above those normally used for cooking. Dupont has also suggested that it is the fumes from the fat in highly-heated pans, rather than those from the non-stick coating itself, which are to blame for bird deaths. However, the biscuits which caused the parrots' deaths were being baked without oil.

In common domestic cooking, like frying bacon or pre-heating pans to make pancakes, temperatures often reach 536°F/280° Centigrade (C). [2] In recent tests a generic non-stick frying pan preheated on a conventional electric stovetop burner reached 736°F in three minutes and 20 seconds, with temperatures still rising when the tests were terminated. A Teflon non-stick frying pan reached 721°F in just five minutes under the same test conditions.

A third source of PFOA is waste incineration, which operates typically at 680°F/360°C. Teflon is used in shatter-proof light bulbs, heat lamps such as those used in factory farming and sealants used in military machinery. Teflon-like compounds known as ‘fluorinated polymers’ (FPs) are used in grease-resistant food wrappings and containers (like Tetrapack cardboard drink and soup containers), stain-resistant textiles, carpets and papers. Although PFOA is not used in the manufacture of FPs, it is created and released when FPs are heated to 680°F. As yet, no-one knows how.

Researchers have found that Teflon heated to 680°F also emits other toxic fumes, including TFE (tetrafluoroethylene), HFP (hexafluoropropene), OFCB (octafluorocyclobutane), PFIB (perfluoroisobutane, a chemical warfare agent ten times more toxic than phosgene, a chemical warfare agent used during World Wars I and II), carbonyl fluoride (the fluorine equivalent of phosgene), CF4 (carbon tetrafluoride), TFA (trifluoroacetic acid), trifluoroacetic acid fluoride, perfluorobutane, MFA (monofluoroacetic acid) which can kill people at low doses, SiF4 (silicon tetrafluoride), HF (hydrofluoric acid, a highly corrosive gas) and particulate matter. [3]

How serious are the health implications?
The fact that PFOA is often fatal for birds tells us nothing, of course, about its dangers for humans (as a different species), but we do know that inhaling PFOA damages human health.

Cancer
A recent study found that cancer rates in the neighbourhood of DuPont’s Parkersburg (Virginia) chemical plant are over twice the US average. Elevated rates of prostate, cervical and uterine cancer, as well as of rarer cancers like non-Hodgkin’s, leukaemia and multiple myeloma were identified. Increased rates were also found in plant employees.

Birth defects
Recently uncovered internal Dupont documents, kept secret by the company for 22 years, revealed that pregnant workers exposed to PFOA passed it to their unborn children, where it significantly raised the risk of birth defects, particularly involving the eyes.

‘Teflon flu’
DuPont accepts that over-heated Teflon cookware releases tiny chemicals which penetrate deep into the lung and cause a ‘flu-like illness. Headaches, chills, backache and temperatures of 100-104°F usually last for two days. The true rates of ‘Teflon flu’ and the temperatures required to release the fumes which cause it have never been properly established. Teflon ‘flu rarely appears on doctors’ records because its symptoms are very similar to common ‘flu and awareness of a possible connection is extremely low.

Cholesterol
A 17-year study covering 35 workers at an Italian chemical plant showed a potential link between blood concentrations of PFOA and a slight rise in cholesterol levels. The significance of the finding is uncertain. Dupont was quick to point out that (i) no adverse health effects had been reported and (ii) the blood PFOA levels found were 180 times higher than found in US Teflon factories (500 parts per billion) and 18,000 times levels found in the general US population (5 parts per billion).
As evidence of adverse effects accumulates, it looks as if perfluorinated acids like PFOA will supplant DDT, polychlorinated biphenyls (PCBs) and dioxin as the most toxic chemical contaminants ever produced.

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Editorial

For reasons we can only guess at, it has taken fifty years for the US Environmental Protection Agency (EPA) to take the potential dangers of Teflon seriously. The first study showing that Teflon emitted fumes when heated was published in 1955. [4] A 1975 study established emissions from Teflon pans heated above 554°F. [5] That the Agency has promised comprehensive research into the possible dangers and is finally pursuing Teflon through the courts, alleging that it criminally suppressed important health information, is in no small measure due to a long, determined campaign by the US environmental campaigning group ‘The Environmental Working Group’.

For further information visit website: www.ewg.org



References

[1] Boucher,M et al. Avian Diseases 2000;44(2):449-53
[2] Ellis,DA et al. Nature 2001;412(6844):321-24
[3] Coleman,WE et al. American Industrial Hygiene Association 1968;29(1):54-60)
[4] Zapp,JA et al. American Industrial Hygiene Association Annual Meeting 1955
[5] Waritz,RS. Environmental Health Perspectives 1975;11:197-202


(11192) Environmental Working Group