Discovered largely by accident in the late 1930s, Teflon has made all our lives a little easier. Waxy, slippery, dirt-, fat- and water-repellent, consumers encounter this amazing material in the coatings on frying pans and cooking utensils, stain-proof carpets and clothes, paper products, fast food packaging, spectacles, insulation on electrical wires and even the fabric roofs covering football stadiums.
Teflon-coated cookware is the ultimate in cookware convenience. It keeps food from sticking to the pan, allows the diet conscious to use less fat while cooking, and makes washing up easier. In fact, it’s so useful that nobody, not even its manufacturer DuPont, has bothered to do much in the way of proving whether it is actually safe to use.
The chemistry of Teflon is so complicated that most scientists don’t fully understand it. What is known is that Teflon is composed of several toxic chemicals that can be released from heated pans into the air and into food. The more often you use your pans at high temperatures, the quicker the coating will break down and emit tiny particles and gases into the air. As this happens (usually within about two years of continual use), washing Teflon-coated pans by hand or in a dishwasher with harsh detergents may accelerate the process further.
The chemicals emitted by Teflon are harmful to humans and deadly, even in minute amounts, to pet birds. Even if you’ve never used a Teflon-coated pan, there’s a good chance that you are carrying some of Teflon’s breakdown products in your body because the substance has a wide range of uses outside the home.
Teflon, known chemically as polytetrafluoroethylene (PTFE), is a plastic-like substance made up of a complex mixture of perfluorinated chemicals (PFCs). All good non-stick coatings intended for use in cooking are made with PTFE. The difference between brands lies in the proportion in which PTFE is blended with other materials.
Unlike environmental villains such as DDT and PCBs, perfluorinated chemicals are not generally volatile. In other words, they do not become easily airborne and so tend not to travel long distances. In addition, to produce a useful substance like Teflon, PFCs are normally ‘locked’ into polymers (plastic-like materials). So it has long been assumed that they could never leak into the environment, that even if they could they would not break down, and that even if they broke down they would be biologically inert.
All of these assumptions are being proved wrong. Today, PFCs are considered dangerous because they fulfil every single criterion for persistent bio-accumulative toxins: that is, they do not biodegrade; they accumulate in people, animals and the environment; and they have been shown in laboratory tests to be toxic to mammals.
Although there are nearly 100 known PFCs, only two have been studied in any depth: perfluorooctane sulfonate (PFOS), a breakdown product of the stain repellent Scotchguard; and perfluorooctanoic acid (PFOA), a breakdown product of Teflon. Both have been found in the blood of nearly every human tested, as well as in the blood of animals in the Arctic and in the Atlantic Ocean.
The quickest way to degrade Teflon is to heat it. DuPont claims publicly that its non-stick coatings are stable up to 600 ° Fahrenheit, a temperature which the company says is well above that reached in everyday cooking.
Independent studies dispute this. The lowest recorded temperature at which Teflon by-products have been detected in the air is 446 ° Fahrenheit. The lowest temperature at which heated non-stick coatings have been reported to kill birds, however, is 396 ° Fahrenheit. This suggests that toxins may be released at much lower temperatures.
In tests conducted in the US by the independent watchdog the Environmental Working Group, cookware coated with Teflon and other nonstick surfaces greatly exceeded these temperatures within two to five minutes on a high setting on a conventional oventop. For example, a generic non-stick frying pan pre-heated on a conventional, electric oven-top burner reached 736° Fahrenheit in three minutes and 20 seconds, and the temperature continued to rise even after the test was terminated. A Teflon pan reached 721° Fahrenheit in just five minutes under the same test. DuPont’s own studies suggest that the average oven-top drip pan can quickly reach temperatures of 1,000° Fahrenheit. At temperatures of 680 ° Fahrenheit and 932 ° Fahrenheit, scientists at the University of Toronto have found that nonstick coatings like Teflon break down into a range of neurotoxins and greenhouse gases.
Heated to temperatures consistent with everyday cooking, Teflon emits minute particles that can lodge deeply in the lungs. These particles are deadly to pet birds and can cause a disease known as polymer fume fever, a severe flu-like condition, in humans.
Polymer fume fever first emerged in factory workers in the 1950s. In an effort to understand more about the condition, DuPont eventually conducted several small-scale animal experiments, the culmination of which was a study in which 12 rats, 10 mice, six guinea pigs, four rabbits and one dog were exposed to Teflon fumes for six hours. The animals did not die and DuPont concluded that polymer fumes were safe. The problem was that their factory workers continued to suffer from what was called ‘the shakes’.
To find out more, DuPont enlisted factory workers to smoke Teflon-laced cigarettes until they became sick and concluded that being a smoker might up the odds of contracting polymer fume fever because the heat from the cigarette acted like a magnet for any fluorinated particles in the air. From this limited data the company concluded that Teflon was generally safe for humans, as long as they weren’t smoking while cooking. Nevertheless, medical journals have continued to report cases of polymer fume fever in homes, and since the mid-1960s DuPont employees have been obliged to wear protective breathing apparatus when working with Teflon heated above 400 ° Fahrenheit.
Apart from being a crude indicator of safety, the effects of these kinds of short-term studies are misleading in other ways. While humans develop polymer fume fever, animals (with the exception of birds, which die an extremely painful and agonising death when exposed to Teflon particles) do not. Also, since PFCs are persistent and bio-accumulate, it is the longer-term effects that may be most important and most devastating.
These problems are only just coming to light because when toxicologists look for environmental poisons in humans they generally only examine fat and blood. But PFCs have been shown to accumulate in human organs like the liver, gall bladder and thyroid gland. In other primates, exposure to one of Teflon’s breakdown products, PFOA, has led to hypothyroidism (the condition of having an underactive thyroid). This effect is also apparent in human studies. A prolonged state of hypothyroidism is a risk for obesity, insulin resistance and thyroid cancer.
Laboratory studies also show that PFOA is toxic to at least nine types of cell that regulate immune function. Cells in the spleen and thymus – both critical to immune function – are particularly vulnerable, and humans exposed to PFOA exhibit reduced immune function. Most recently, PFOA has been linked to raised cholesterol and triglyceride (blood fat) levels in factory workers and, in animals potentially dangerous changes in the size and weight of several important organs such as the brain, liver and spleen.
Perfluorinates also act like skeleton keys in the endocrine system (the body’s communications network), activating deranged and mistimed hormonal signalling. This is a potential trigger for cancer, infertility and developmental abnormalities. Exposure in early life is thought to be particularly harmful. Data uncovered by the US Environmental Protection Agency shows that DuPont has known since 1981 that PFOA is passed from mother to child and that it can cause the same facial abnormalities in humans noted in animal studies.
In addition to being released in normal household use, perfl uorinates can spill into the environment during their manufacture and application. Local residents and factory employees are on the front line of any human health fallout. Much of what is known about the toxicity of Teflon’s constituent parts comes from studies of these individuals.
In 2001, residents living near DuPont’s Washington Works plant in West Virginia fi led a legal action against the company alleging that it knowingly contaminated waterways near the site. Research commissioned by the residents found a statistically significant excess of prostate cancer and female reproductive cancers in the area compared to the US average. The residents also managed to obtain the health records of 5,000 DuPont employees at the site and found an excess of these and other more uncommon cancers such as non-Hodgkin’s lymphoma, leukaemia and multiple myeloma.
In March this year (2005) a West Virginia judge approved a settlement in which DuPont agreed to spend at least $107m to reduce PFOA emissions from the factory and fund a study into the human health effects of PFOA contamination in the community water supply. Depending on the outcome of the study, DuPont could be liable for another $235m to establish a long-term medical monitoring programme to help residents detect disease and seek early treatment.
Sold for decades as the ‘housewife’s best friend’, the safety of Teflon has never been proven by any rigorous scientific study. Although DuPont claims that its non-stick coatings are stable at all but the highest temperatures, this clearly is not the case. All available evidence suggests that Teflon’s breakdown products have caused enough problems over a wide enough range of mammals, including primates, to indicate an urgent need for more human data, and yet no such data exists.
Consumer groups in the US are demanding that Teflon pans carry a health warning. But does this really go far enough? Consider some of the unanswered questions surrounding this substance:
• How toxic are all of Teflon’s various constituents to humans?
• What besides heat causes Teflon to break down?
• How do Teflon by-products get into animals in pristine wildernesses?
• How much goes into our food when we cook?
• How much goes down the drain when the pans are scrubbed by hand or put in the dishwasher?
• How many cases of polymer fume fever in the home are mistakenly diagnosed as ‘flu’?
• Apart from birds, which other household pets might be affected by Teflon fumes?
• What’s the most responsible way to dispose of Teflon pans?
Teflon may reduce the amount of fat we cook with, make washing up easier and clothes and carpets last longer; but it is a frivolous and unnecessary substance the benefits of which pale beside the possibility of killing beloved pets and raising your risk of heart disease, diabetes, birth defects and cancer.
In accordance with the precautionary principle, Teflon should be withdrawn completely from household use until DuPont can produce incontrovertible evidence that this artificial chemical compound is safe to use. If such data is not forthcoming it’s easy to predict a future in which legal action could bring Teflon’s manufacturer to its knees.
GIVING OFF GAS
At every stage of the heating-up process Teflon-coated pans emit a range of toxic gases and particles capable of making humans and animals very sick. Among these are neurotoxins, greenhouse gasses and even agents used in chemical weapons.
TEMPERATURE WHAT GOES INTO THE AIR
Ultrafine particulate matter These particles have caused extreme lung damage to rats within 10 minutes of exposure. Longer exposures cause death.
Difluoroacetic acid Largely unstudied, although kidney toxicity has been reported in rats.
Hexafluoropropene Produces decreased immunity and chromosomal abnormalities in animals. In people, it can lead to eye, nose and throat irritation, heart palpitations, irregular heart rate, headaches, light-headedness, and decreased motor speed, memory and learning.
Monofluoroacetic acid Can kill people even in extremely low doses. Low doses provoke nervous system symptoms. Higher exposures can lead to irregular heart rate, heart attacks and respiratory failure.
Perfluorooctanoic acid Causes four types of tumours in rats – in the liver, pancreas, mammary gland (breast) and testes. Similar effects have also been noted in humans. It has also been linked to hypothyroidism and raised cholesterol.
Tetrafluoroethylene A potential kidney and liver carcinogen known to cause cancer in laboratory animals.
Trifluoroacetic acid Causes bone abnormalities and birth defects in animals.
Silicon tetrafluoride A highly toxic, corrosive gas that can cause eye and throat irritation, difficult breathing, bluish skin colour from lack of oxygen, lung damage and lung oedema. Long-term exposure can cause weight loss, decreased numbers of red and white blood cells, discoloration of the teeth and abnormal thickening of the bone.
Perfluoroisobutene A highly toxic corrosive chemical warfare agent. Symptoms in people include bad taste in mouth, nausea and weakness. Lung oedema occurs about one to four hours after exposure.
Carbonyl fluoride A fluoridated version of a WWI chemical warfare agent. Fumes can irritate eyes, ears and nose. More serious symptoms of exposure include chest pains, breathing difficulty, fluid accumulation in the lungs, liver damage and increased glucose levels.
Hydrogen fluoride A toxic corrosive gas that can cause death to any tissue it comes into contact with, including the lungs.
Octafluorocyclobutane Can cause heartbeat irregularities, unconsciousness and death. People with pre-existing heart conditions may be extra vulnerable.
Perfluorobutane A global warming chemical. Untested for long-term effects in humans.
Trifluoroacetic acid fluoride Largely unstudied, but can cause foetal bone abnormalities and neural tube defects in rats.
Carbon tetrafluoride A refrigerant and potent greenhouse gas. Can cause eye, ear and nose irritation, heart palpitations, irregular heart rate, headaches, confusion, lung irritation, tremors and, occasionally, coma.
THERE’S TEFLON IN EVERYTHING!
Airplane parts, exteriors and coatings
Anti-wrinkle creams and treatments (eg, skin injections)
Auto engine parts
Camping equipment and outdoor clothing – eg, Goretex
Carpets and rugs
Clothing for adults, children and infants
Curling irons/ hair straighteners
Fast food container linings
Furniture – sofas, chairs, beds
Gardening equipment and patio furniture
House paint, interior and exterior
Kitchen utensils and gadgets
Irons and ironing board covers
Nail polish and hardener
Pet bedding, leashes, collars and harnesses
Prosthetic devices and reconstructive surgery
Razor blades and shaving foam/ gel
Solar panel coatings
Spectacles with scratch-resistant lenses
WHAT CAN YOU DO?
Although some exposures to PFCs are unavoidable, as a consumer you can choose not to spend money on products containing Teflon. Consider these suggestions:
• Replace Teflon cookware. Consider using stainless steel, cast iron, Pyrex or enamel coated cookware instead.
• Look for the Teflon label on carpets and clothes. With normal wear and tear, these
coatings could break down and contaminate your home and family. If you are unsure
whether the fabric has been treated with Teflon, ask. Make it clear to your retailer that
Teflon coatings are unacceptable to you.
• Forget fast food. It’s likely to be packaged in PFC-coated boxes and paper. PFCs, the chemicals Tefl on is made from, are also used in containers for a wide variety of supermarket foods, including microwave French fries, pizzas and popcorn.
• Avoid cosmetics and toiletries with ‘fluoro’, ‘perfluoro’ or PTFE on the ingredient list. Products that might contain PFCs include face and body lotions, pressed powders, nail polish, and shaving cream.
• Start a campaign. In the US, the Environmental Working Group has been very vocal about the human and environmental impact of PFCs. In the UK, the World Wildlife Fund, Friends of the Earth and Greenpeace all recognise that PFCs are widespread pollutants, but full information on this family of chemicals is still hard to come by here.
• For more information about Teflon, visit the Environmental Working Group website at www.ewg.org and the FAN Pesticide project website www.fluoridealert.org,
which contains numerous studies into the health effects of exposure to Teflon- , PFOS and PFOA-containing pesticides. You can find these by using the site search engine or clicking on the fluorinated pesticides bar.
This article first appeared in the Ecologist June 2005