We associate PTFE with Teflon, however, it is not the same. And there is also a belief that PTFE is toxic. We delve into these issues, based on scientific evidence, to try to clarify these concepts and understand what materials we can use in the kitchen without risk of toxicity and how to use them.
What is PTFE?
PTFE is polytetrafluoroethylene, to understand us in the world of cooking, it is the external and black non-stick layer that covers many of our utensils and we commonly call Teflon. “Teflon” is the commercial name that Dupont (the American chemical company that invented PTFE) gave to this substance.
Chemically, PTFE is a fluoropolymer, a plastic material that resembles polyethylene, except that PTFE has fluorine atoms whereas polyethylene has hydrogen atoms. The arrangement of this chain of monomers gives Teflon very special characteristics, which have made it a substance with very versatile characteristics and that give rise to a wide variety of applications. Let’s see the most important characteristics of PTFE:
- Low coefficient of friction: It is the material with the lowest coefficient of friction known, so it is perfect for covering mechanical parts that suffer friction, such as bullets, gears, articulated parts, or bone prostheses. Sealant and lubricant in many uses, it was even used to seal the joints of the atomic bomb. Its ease of sliding makes it useful, for example, on windshield wiper blades to prevent them from squeaking, on slides or ski soles.
- Inert and non-bioavailable: Since it is a large and stable molecule, it does not react with our body or with chemicals. For this reason, it is used not only in prosthetics but also in artificial tissues, blood vessels, heart valves, and sutures. Also because it is inert, it is used in hoses or ducts that come into contact with corrosive substances.
- Flexibility: Allows the use of PTFE in body tissues (for example, meshes that are inserted in hernia operations) and in piercings that allow the jewel to adapt in the event of a blow or physical changes.
- Non-stick: non-stick is applied by coating the surface of kitchen utensils. It also allows easy unmoulding, very useful in the kitchen, in molds from different types of industries, or the baking industry (for example for kneading utensils). It is also used to prevent insects or reptiles from climbing on PTFE-coated surfaces. In surgery, in addition to being used for being inert, flexible, and resistant to friction, it is interesting because it inhibits the growth of microorganisms as they cannot adhere.
- Insulator – For cable sheathing, connectors, and circuit boards.
- Impermeability: the famous membranes that waterproof clothing and footwear, while being breathable, are made of PTFE.
- It supports large temperature differences: Allowing it to be used as a coating for airplanes, rockets, spacecraft, and pipes that transport very hot liquids.
Of all these characteristics, the one we are most interested in investigating is the fact that it is an inert substance, that is, it does not react with other chemical substances, a topic whose controversy we are going to study in detail in this document.
Teflon, PTFE, and PFOA: why the controversy?
The substance that caused the controversy around Teflon is PFOA. These acronyms correspond to Perfluorooctanoic Acid, also known as C-8.
Teflon was invented in 1938 and has been used in frying pans since 1961, using PFOA as an emulsifier in the manufacture of PTFE. That is, PFOA (or another similar substance) was used in the PTFE manufacturing process and only a trace of PFOA remained in the final product.
The controversy over the toxicity of PFOA arose in 2001 when DuPont was accused of hiding its harmful effects on health, such as carcinogenic and teratogenic (causing cancer and malformations in fetuses). Although DuPont initially denied this toxicity, it seems to have known about it since the invention of Teflon and was fined $16.5 million in 2005 for exposing its workers and for highly toxic discharges. In addition, it had to commit to stopping using PFOA by 2015.
The main PFAS manufacturing companies (including PFOA) are committed to seeking alternatives and eliminating these substances from products and emissions (2), with scientific support that demonstrates safety for health and the environment.
The controversy over the toxicity of Teflon was never associated with PTFE, although the fact of relating PTFE=Teflon gives rise to the popular belief that Teflon is toxic and therefore PTFE is. PTFE is not toxic, but there are some aspects to clarify in this regard.
- PTFE is the black non-stick coating that we see on pans. It is innocuous.
- PFOA was an emulsifier used in the manufacture of PTFE. It is toxic.
- Teflon is Dupont’s proprietary coating of PTFE, PFOA, and possibly other substances.
PFOA belongs to the group of perfluoroalkyl, a group of persistent substances that are concentrated in the food chain. Of these compounds, their accumulation in tissues and their toxicity, such as endocrine alterations, thyroid and liver carcinogenicity, and developmental alterations are known.
PFOA has been subjected to numerous studies, in which its toxicity has been clear in animal studies (cancers, fetal problems, immune system problems, thyroid disorders, ulcerative colitis, fat metabolism problems) although no studies are determining its effect in humans.
The routes of action are not known, but there is sufficient evidence of its toxicity and the IARC classifies it as a «possible carcinogen in humans» with limited evidence and for REACH it is a substance of high concern.
- It remains in our body for 8 to 9 years, it is a substance that is excreted by the kidneys and is not metabolized.
- The people who are exposed to levels of greatest concern are workers at chemical plants where PFOA is used or people or animals who drink water where it has been released.
- It is one of those substances that is estimated to be found in the blood of 95% of living beings on the planet and if we had been able to choose, no one would have wanted to carry it inside.
Having brought to light the toxicity of PFOA and, in addition, of the other perfluoroalkyl or PFAAs, has given rise to regulation and control, which we see below.
PTFE, inert substance
After all the evidence on the toxicity of PFOA, we find that PTFE is a substance that is unanimously considered inert and biocompatible, that is, a stable substance that does not interact in our body and does not produce toxicity.
This feature, according to chemical experts, is due to the strength of their fluoro-carbon chains. The fluorine atoms form a practically impenetrable barrier to the attack of other molecules, preventing them from reacting with the carbon. Therefore no other molecules can adhere to it, except other equal Teflon molecules. It also has a high resistance to acids, bases, organic solvents, ozone, and hydrocarbons.
PTFE is part of a group called “ polymers of low concern ” (or PLC, “Polymers of Low Concern”) to differentiate it from other “polymers of high concern” (or SVHC, “Substance of Very High Concern”), of proven toxicity such as PFOA, PFOS, PFAS. Due to the size of PTFE molecules, they do not cross the cell membrane and are not bioaccumulative or bioavailable (13).
One of the reasons why there is a lot of research on the toxicity of PTFE is because of its use as a biomaterial. (There is extensive literature that seeks its effectiveness and absence of toxicity in the use of PTFE to replace cartilage, bone, tendons, prostheses, vascular grafts, catheters, sutures… and as a bioadhesive. In other words, once PTFE is inserted into our body, it does not cause undesirable effects, at a local or systemic level, generating at the same time a good response at the cellular and tissue level, being a material of choice due to its low capacity to induce a response. Teflon is implanted as a mesh in a hernia, the abdominal tissue grows between the mesh, the PTFE being integrated into the person’s body. reinforced with Teflon!
Also by the digestive route, it is considered an inert material and is even used in such surprising use as increasing the volume of the food bolus to give a feeling of satiety and eat less.
Although all the studies refer to the fact that it is biocompatible, we also found a study that speaks of the induction of an inflammatory reaction in vitro. The surgical use of PTFE can give rise to granulomas, that is, an inflammatory reaction. This occurs due to the presence of a foreign body, not due to the material itself. In other words, it is not due to the toxicity of the PTFE molecule, but rather to the fact that the body reacts to the implant as a foreign body that it does not recognize, just as it could react to a foreign body made of any other material.
However, despite being such a safe product, it has two drawbacks that we are going to analyze, regarding its purity and temperatures.
PTFE toxicity by surfactants. Regulation
PTFE itself is an inert, biocompatible, and non-toxic substance, but it may contain residues of the surfactants used in its manufacture. They can be recognized by the names PFAS or polyfluoroalkyls or fluorosurfactants and the best known specific substances are PFOA, PFOS, PFHxA, and GenX, being those that can give rise to toxicity. These PFAS are SVHCs (Substances of High Concern), while PTFE is a PLC (Polymer of Low Concern). It is impossible to make fluoropolymers without these surfactants, which act as emulsifiers.
The good news is that in 2005 the EPA (USA Environmental Protection Agency) forced the largest companies in the sector to regulate the manufacture, import, and use of PFAS. They had to reduce the manufacturing, emissions, and presence of PFAS by 95% in 4 years and completely by 2015. At that time, the industry ensured that the PFOA content in Teflon was under control, being the main challenge to eliminate it from waterproofing in textiles.
So the question is: are there residues of these fluorosurfactants currently in the PTFE in our pans?
According to the FluoroCouncil, the association of manufacturers of the fluorine industry (to which the large manufacturers of Europe, the USA, and Japan are affiliated), toxic PFAS have been replaced by non-toxic substances and are currently found in PTFE in a proportion of less than 0.01%. These traces are impossible to remove because they are embedded in the PTFE matrix. For this same reason, they cannot be released by cooking. They cannot be removed from PTFE by any means and would not pose a health risk.
It appears that PFOA was partly replaced by another substance called GenX in nonstick coatings.
According to Greenpeace (2016), the production of PFOA has moved to China, to the Shandong region, and this PFOA is imported (at least to the US, according to the EPA) for the manufacture of consumer goods such as carpets, leather, and clothing, textiles, paper and packaging, coatings, rubber, and plastics.
This production of PFOA for textiles and waterproofing is a focus of attention for Greenpeace and is being actively worked on, with companies already replacing fluorine-based waterproofing membranes with totally different substances, without fluorine and free of toxicity.
Honestly, it is amazing to see how complicated and long it takes to eliminate something from the commercial chain (and what to say about the elimination of its effects on ecosystems and living beings…), for example, happened with PCBs (polychlorinated biphenyls), after 50 years of complaints and alerts by the scientific community and free exposure to the population (with effects on reproductive health, hormonal changes, neurological development) for the benefit of the industry.
PTFE toxicity and temperature
As we have seen, PTFE is an inert material in its solid form, but when subjected to certain temperatures it releases toxic gases. This is the topic that generates controversy and confusion regarding PTFE in its use in the kitchen and that we are going to analyze carefully.
PTFE behavior according to temperature
- The thermal degradation of PTFE occurs from 342 ºC, which is its melting point.
- It behaves in a stable way between -240ºC minimum temperature and +260ºC maximum temperature, that is, its physical properties are not altered between these temperatures.
- From 260 ºC toxic gases are formed. This temperature can be reached by heating an empty frying pan over high heat for several minutes. However, at normal cooking temperatures with a frying pan, toxic release temperatures are not reached.
PTFE toxicity in birds
The topic of the toxicity of PTFE when releasing gases is associated with the death of birds when inhaling gases due to the heating of this material. Birds can die from inhaling gases from overheated pans (there is evidence in the scientific literature of cases of birds dying from inhalation of PTFE gases.
We want to understand if the case of birds can be extrapolated to humans, we collect the following data:
- According to bird experts… “ The respiratory tract of birds is extremely sensitive to airborne toxins due to their unique anatomy. It is extremely efficient at exchanging gases to provide very high levels of oxygen to the muscles for flight. While it delivers oxygen so efficiently, it can also deliver toxic gases. In addition, the small size and high metabolic rate of birds increase their susceptibility to airborne toxins. Birds, often canaries, have historically been used as sentinels for toxic gases in coal mines due to this increased sensitivity.
- The anatomical structure of birds allows a very efficient gas exchange, thus increasing oxygen concentrations. If gas or toxin is found in the inhaled air, it is also concentrated, causing severe respiratory compromise.
- We found a case that supports the different bird-human susceptibility to PTFE gases: after exposure to an accidentally overheated frying pan, some cockatoos died, while the owner recovered within 24 hours from the symptoms of “polymer fever”.
- In addition, not all birds have the same sensitivity: for example, the lethal temperature for parakeets is 280ºC, while for quail it is 330ºC and for rats, the lethal temperature is 425 to 450ºC.
In other words, the emission of gases when overheating a PTFE-coated product does not pose the same toxicity to people as it does to birds.
Let’s now analyze the toxicity for people.
PTFE, gases and human beings: the fever of the polymer
PTFE generates toxic gases if its thermal degradation occurs, which according to authors occurs at 240 ºC, at 250 ºC, or according to others, at 350 ºC. If these gases are inhaled, the effect on our health is the so-called ” polymer fever “, a complex of self-limiting symptoms (which tend to resolve on their own) and similar to the flu that has been reported mainly in cases of:
- Chronic exposure in workers with PTFE: the most intense exposure is occupational exposure, for example, of people who work applying coatings (which generates aerosols) and at the same time handle high-temperature ovens (380-420 ºC) and workers who carry out welds.
- Cigarettes: Cases of people showing symptoms of poisoning from smoking PTFE-contaminated cigarettes due to handling PTFE, not washing hands, and smoking.
- Intense overheating and very deteriorated pans: to study the effects on the lungs of rats, they are subjected to Teflon heating fumes, heating it to 450 ºC so that aerosols can be generated by ultrafine particles and in this study, it is heated to 486 ºC to give rise to ultrafine particles that allow understanding its toxicity in studies with rats and mice. We also found a case of a person who developed polymer fever with the use of a frying pan, although the frying pan is in such a deteriorated state that we understand that we wonder if it can be attributed to PTFE because of the state of the pan
- Other cases: polymer fever with pneumonia and another with pulmonary edema.
Nanoparticles and PTFE
Just as the absence of toxicity of PTFE in the form of macroparticles is clear, there is evidence of the toxicity of PTFE nanoparticles. We have found this evidence in studies that investigate toxicity in biomedical and industrial applications, where they show that there is toxicity depending on the fluorine content, with a greater ability to cross cell membranes when the fluorine content is lower.
Therefore, the principle of prudence is the reason why at Conasi we only sell SKK, since it does not use nanotechnology. We did not find toxicological studies on the repercussion on the health of these materials when migrating to food. We know that there is no toxicity in PTFE particles, let’s say “normal”, macroparticles, but when we talk about the nanoscale everything is as uncertain as to when we talk about transgenics. There is NO legislation for this technology or obligation to indicate when a product uses it, so this, together with the doubts about the health risks of these particles, makes it more than justified for us to consult the use of nanotechnology to the manufacturers and do not incorporate the products that do use it.
That is, we are not aware of any reported toxicity of PTFE in humans in cases of the normal use of a frying pan.
Now, finally, we are going to analyze environmental toxicity.
PTFE and the environment
PTFE is a fluoropolymer, that is, a molecule with fluorine that is not part of the so-called “PFCs of environmental concern” considered dangerous, because it is a stable molecule, very large, and not bioavailable (if PTFE is ingested, it is excreted without modifying ).
Fluoropolymers have unmatched thermal and chemical stability, providing strength, elasticity, and durability for operation in a variety of products and industries. Fluoropolymers are extremely stable high molecular weight polymers, too large to be bioavailable or toxic, insoluble in water and non-mobile, do not degrade in the environment to perfluoroalkyl acids, and therefore do not present a significant risk to human health. or the environment. As a result, regulators do not require the development of meaningful toxicity data on fluoropolymers. For more information:
Fluoropolymers are persistent, not reacting with anything or degrading with temperature, light, oxidation, or microorganisms. This is why there is currently no regulation or control of fluoropolymers, nor pressure from environmental or health protection agencies.
The only point of environmental toxicity regarding PTFE refers to the end of its useful life, since although it does not degrade in the environment nor does it release substances of toxicological or environmental interest, in the event of incineration it would release dangerous substances from the 450 ºC, so incineration must be avoided.
But just like in the issue of human health, the problem of environmental contamination is in the emissions generated with the other substances necessary to manufacture PTFE, such as PFOA.
The great alarm generated by the toxicity of PFOA and Dupont put perfluorinated substances in the spotlight, as they are bioavailable and persistent. For this reason, regulations and controls were established to establish responsible practices. Some fluorinated substances have had to stop being used and look for non-toxic alternatives.
This seems to be the case in Europe, Japan, and the USA and we have up-to-date data and apparently, an intention of transparency after the damage caused and revealed. And it seems that the production of PFAAs in China is also being regulated.
Conclusions and current panorama regarding fluorinated substances
What we can look back on is that the damage has been done. All PFAAS released into the environment will be there for years due to their persistence and will interact with organisms because they are bioavailable.
Currently, due to what happened with Dupont, fluorinated substances are perhaps one of the most closely watched substances, with active monitoring (both by government agencies and by organizations in defense of health and the environment) and a large amount of information available, from all points of view.
After the most exhaustive study that we have been able to carry out, contrasting the information as much as possible, we come to the conclusion that PTFE (and also taking into account the substances necessary for its manufacture) is applied to frying pans today in Europe It does not imply toxicity for cooking and according to the data we have found and refer to in this document, neither for the environment.
The main current problem is not the presence of surfactants in the utensil we use for cooking, but the emission of PFOA and similar substances that continue to be manufactured in China, its main application being waterproofing, textiles, paper, packaging (as we mentioned above ). This manufacturing is a current environmental problem as well as its subsequent elimination.
Therefore, our attitude from Conasi is:
- Use non-stick when necessary: mainly in pans or grills, for preparations in which food can stick when cooked with little fat or liquid. Choose materials with less environmental impact for other uses for which there are alternatives: silicone molds, paper to protect oven trays, cooking with glass or porcelain whenever possible…
- Choose the PTFE that ensures greater resistance and duration, as in the case of PTFE reinforced with titanium.
- Avoid utensils from before 2015.
- Use PTFE-coated utensils at normal cooking temperatures, avoiding accidents due to burning oils or overheating by forgetting a pan on the stove and emptying it.
- Choose products manufactured in Europe, from responsible companies that certify us that they do not use PFOA or similar substances.
- Properly care for and clean nonstick cookware to maximize shelf life.
- Make us aware of other products that we possibly use and that contain PFOA or similar substances and that may be causing us greater exposure than that of the kitchen: waterproof clothing and shoes; stain-resistant fabrics (eg upholstery) and mats, food packaging (eg to prevent grease soaking such as popcorn bags, pizza boxes, chip boxes…), cosmetic products with “fluoro » or «perfluoro» in the list of ingredients (lotions, pressed powders, nail polishes, shaving creams).
Care and cleaning of pans with PTFE nonstick
These are specific guidelines for PTFE nonstick, based on our experience since 2010 with SKK pans. We understand that they can be extrapolated to all non-stick pans:
- Before the first use: it is not necessary to season, apply oil, or use a vacuum, just wash to remove any residue or dust, as would be done with any other utensil that will be in contact with food.
- Let cool before washing: in SKK utensils there is no problem putting water just after cooking with the pan, but as a general rule it is better to wait for it to cool down so as not to subject it to thermal shock.
- Wash in the dishwasher: although it can be done on occasion, it is not recommended since the detergents, and especially the salt from the dishwasher, deteriorate the surface of the non-stick.
- Detergents and scouring pads: We should not use abrasive products to clean, although we must also recommend the correct removal of grease. This is something we have learned over the years, receiving inquiries from people who, after using SKK pans for a long time, realize that the food is beginning to stick, even though the nonstick looks perfect (in pans non-stick of inferior quality this does not happen, since the non-stick is lost or deteriorates sooner). We have found that prolonged use can lead to the creation of an imperceptible layer of grease, aggravated by the use of mild detergents. This is perfect, although the elimination of fat may not be total and the cumulative effect over time, together with the use of little oil (which results in the food being in more contact with the base) and also very soft scouring pads, it can lead to the fat not being completely removed. Therefore, the recommendation is to do a proper cleaning, not using aggressive scouring pads but using hot water and detergents that ensure the removal of grease.
- Do not use pans with deteriorated non-stick coating: If a pan is scratched or has lost its non-stick coating due to use, or the food has stuck to it and the non-stick coating has deteriorated to be able to clean it, it should not be used any longer. The reason is that the deteriorated surface lets through materials that are below the surface layer. The only exception is cases where there is a healthy material under the non-stick layer, as is the case with SKK, which has the titanium-reinforced layer under the PTFE on the outside.
- More guidance on the general use of all types of frying pans, including non-stick.
Why we choose SKK
After detailing all the possible aspects of the different materials for pans and the use and toxicity of PTFE, at Conasi we feel that the fact that we sell SKK pans is sufficiently detailed and justified, even though there are many other non-stick options on the market. We only sell SKK non-stick pans because:
- SKK is a German company that manufactures kitchenware with titanium-reinforced PTFE nonstick: this gives it a much longer life than other PTFEs on the market.
- The PTFE that SKK projects in its frying pans are manufactured by ILAG, a Swiss company that certifies that it does not use PFAAs in the manufacture of its products.
- Nanotechnology is not used in the nonstick or any of the other parts of the pan, that is, neither in the body nor in any of the 3 layers that make up the nonstick (differentiating fact with other brands).
- The body of the pans is made of cast aluminum, they are pieces for life, non-deformable, with a diffuser bottom that can be coated again by SKK if required over the years.
- After all the experience of use, they have amply demonstrated their quality.
- They are recommended and used by people suffering from Multiple Chemical Sensitivity Syndrome.