Table of Contents
You may hear that cast iron can harm your health by extensive iron leaking, or by exposing you to heavy metals. In addition, you may be wondering about the safety of exposing yourself to residues from cast iron or rust that can commonly appear on this type of cookware.
These are all the questions that were going around my head some years ago when I was thinking to buy cast iron pieces by myself for the first time.
I spent literally dozens of hours in reading the scientific literature related to cast iron safety and all of the questions I had around it.
THe driving solid conclusions about this topic was tough for a while because of a lot of contradictions in the scientific literature. However, my education in Biochemistry and Physiology that I was able to acquire during my bachelor’s, master’s and now PhD in biotechnology and biochemistry really helped me to better understand the topic of cast iron safety.
Finally, now I want to share with you the summary of the conclusions I made since I haven’t found any blog post that comprehensively answered doubts about the safety of cast iron.
This article is primarily divided into a few main concerns/questions about cast iron cookware safety, covered by a short conclusion about each. In addition, in-depth explanations, illustrations and scientific references will be provided in the body of each chapter in case you would like to dig deeper into the topic.
So let’s start with the main questions about cast iron cookware safety
Gratitude: The creation of this post was made possible thanks to people who supported Safetouseit through small donations, and I want to extend my gratitude to them here as well!
If you wish to contribute to independent cookware safety and performance research, as well as bringing it to the world through creating posts like this one, consider supporting my work by small donations through platforms like Safetouseit’s Ko-fi page)
1. Is Cast iron safe? (What are the main concerns)
1.1.Can cast iron cause exposure to iron that can lead to iron overload?
Before answering this question, I feel it will be important to understand is do our body st all absorb the iron from the cookware, and if yes in which percentage.
I heard many misconceptions about this around some blog posts and here I want to break them out.
1.1.1.How available is the iron leaked from Cast iron and food for the body?
Main conclusion: Iron coming from cast iron and other cookware belongs to the non-heme form of iron(see upcoming paragraphs) which is the same form of iron our body takes from legumes, nuts, and cereal-based products as well as iron supplementation. In addition,Fe leaked from the cookware is absorbed in our bodies through the same mechanisms as non-heme iron from other sources. Our gut takes less than 10% of non-heme iron from the total amount of iron ingested (Usually around 2-7%) while the rest finished in feces.
Iron is absorbed by our gut in two main forms, heme and non-heme iron(see more detailed info about each one in upcoming paragraphs), while the absorption mostly takes place in the upper small intestine, ( a part of your gut just after the stomach). (1.)
Depending on the form (hem or non-hem) Fe is absorbed in by different efficiencies. Moreover, other molecules from the food may affect Fe intake efficiency by the gut.
To dig deeper to more into all of this topic and to explain what hene and non-heme actually are, I narrowed down the following few paragraphs.
Heme iron
Hem iron counts for Fe bonded to heme, one of the main components of the haemoglobin protein, the main carrier of oxygen in the blood of humans( and also many animals).
Heme iron is highly available for absorption by gut cells, and its main food source is meat.
Moreover, the absorption of hem iron is poorly affected by the other components ingested through food. It has been shown that 25-30%(2) of total heme iron from organic meat is absorbed by the gut cells
However, even meat-based iron is highly absorbed by the human organism it only presents a small portion of the total iron uptake from the food in a typical Western diet (1. )This is contrary to the common belief that meat is one of the main iron sources.
Meet can be reached in the iron(especially the liver). However, ingredients such as seeds and vegetables, which are commonly consumed in our diet can be much reacher in this element( Take a look at table 1). These food ingredients are sourced from non-heme iron.
Non-heme iron
Non-heme is the one coming from legumes, cereals, and iron supplementation as well as the leaking of FE from cookware like cast iron (1.). Basically the non-heme iron counts for the iron ions coming from the iron salts present in the food and supplementation.
It has been reported that gut cells absorb around 7–9% of iron from green leafy vegetables, 4% in grains, and 2% in dried legumes(2).
In addition, not much data has been published directly on the iron absorption directly from the cookware. However, it can be expected that the absorbance of cookware-derived iron is probably also low(Bellow 10%) since it also belongs to non-heme iron coming from mentioned food sources.
As mentioned, even though many people believe that meat is one of the most abundant sources of iron and that heme iron coming from meat is the major supply of our body with Fe, this is one big misconception.
It is true that heme iron is absorbed more efficiently than the gut, compared to nonheme iron. However, the iron found in cereal-based products, veggies, and nuts is present in a much bigger concentration in these ingredients than the iron in meat.
In addition, some scientific publications est estimated that 90% of iron from a whole diet(Based on the average EU market basket ) comes from non-hem sources( 1). The reason is that cereals, legumes, nuts and seeds are very rich in iron (much more than meat) as you will be able to see in the upcoming table.
Finally, the absorption efficiency of Non-hem iron in the gut can be significantly affected by the other molecules
For instance, the vitamin C(ascorbic acid) present in citrus fruits increases the absorption of non-heme iron, while the molecules like phytates, and polyphenols abundant in cereals, coffee and tea inhibit non-hem iron absorption that comes from food or cookware(.3).
This is why iron supplements(also a source of non-hem iron) are commonly sold as tablets that also contain vitamin C and why taking tea or coffee before or after iron supplementation is not recommended.
1.1.2.Can leaking of metal from cast iron cause iron overload?
Main conclusion: It is highly probable that Leaking of iron from cast iron cookware does not lead to iron overload . While small amounts of iron may be released from cast iron cookware to food during cooking(up to several dozens mg per meal) , the actual amount absorbed by the body though food prepared in cast iron is usually small and unlikely to lead to iron overload. The only ever reported iron overload caused by intake of food and drinks is reported in Subsaharien region, where individuals sensitive to iron get exposed to high quantities of Fe from traditional, homemade bear fermented in cast iron barrel. Such people are exposed to Fe level up to several hundred mg of Fe per day.
In this chapter, I would primarily talk about exposure to non-heme iron form and its potential contribution to iron overload. Moreover, because of the two reasons my focus here will be on the non-heme iron and not on the heme one.
The first reason is that non-heme iron is one leaking cast iron cookware.
And second, overdosing with iron has been mainly associated with non-heme iron from different sources, and not with one in heme form (3.).
First, let’s talk about how much non-heme iron is too much for organisms and what the limitations are set by world health authorities. Then we can pass a summary of the research on how much iron accrual leaks from cast iron cookware and if these amounts are significant compared to iron uptake limit recommendations.
Iron upper uptake recommendations
Based on the US National Institute of Health current upper uptake limitation of iron is 45mg/day for an adult man (4.) Nevertheless, even this limitation can be taken s a starting point, let’s see based on what it was set and should we use it as a limit for iron exposure leaking from cookware.
As referenced by the Washington Institute of Medicine (5.) the intake limitation of 45mg/day was set based on the appearance of Gastrointestinal problems that can occur if the body is exposed to iron supplementation capsules in doses higher than this.
However, the mentioned gastrointestinal problems like nausea, vomiting, and diarrhoea are only present if the iron supplementation is taken on an empty stomach without food(5). However, as described in the same reference taking non-heme iron from supplementation in amounts of 45 mg/day with food hasn’t led to any gastrointestinal problems.
Conclusively, there is no evidence that 45mg/day of non-heme Fe leaked from cast iron cookware to food will cause gastrointestinal problems (as it is demonstrated the mentioned symptoms don’t occur for intaking non-heme iron from Fe supplementation together with food.)
So, if there is no evidence that 45mg/day of non-heme iron taken from iron supplementation(or cast iron cookware) with food will cause any serious problems at what doses do non-hem Fe gets “critical” for health when taken orally with food?
The answer is probably in much higher doses than 45mg/day
Only ever reported adverse effects of iron from orally ingested food or drinks is related to Subsahara region. In this part of Africa people are exposed to high quantities of iron from traditional, homemade beer fermented in cast iron barrels.
It has been reported that the bear prepared traditionally in this region can contain 46-82mg/L of iron. Moreover, it is common for people to drink a few letters during a day(6.).
Furthermore, it in case of Subsacharian people it was reported that more serious advertise effects may come after exposure to non-heme iron in such amounts( probably a few hundred mg of Fe per day). The symptoms may included accumulation of fibrous tissue (fibrosis) in the liver and, eventually, scarring of the liver (cirrhosis)(6.).
However, it has been noticed that in the people in Subsacharian regions exposed to iron in this way, only some individuals mentioned adverse effects may occur while others don’t, even after exposure to the same doses of iron.
Futhermore, some more recent studies suggested that Subsacharan iron overload only exist in people with genetical predispositions for it(6.1, 6,2).
This was another suggestion that some critical iron effects(like fibrosis or cirrhosis of the liver) of iron exposure happen in amounts quite higher than 45mg/day suggested by world health authorities as referenced earlier. Moreover, even in doses as high as a few hundred mg/day, the downside effects can happen mainly in people with a genetic predisposition for sensitivity to iron(6.).
Finally, only confirmed serious toxic effects of Fe have been shown in cases of very high acute acute exposure to (Exposure to just one dose) to this metal. As referenced by the Washington Institute of Medicine systemic toxicity of iron to body occurs at doses of 60 mg/kg of the body ( 4200mg for a 70kg person ) (5.).
Now afgter understanding btetter the doses of iron expoure required for Iron overload lets see how much cast iron cookware increse our iron uptake at all.
How much we are exposed to iron coming from cast iron cookware?
Multiple studies have been conducted on the topic of iron leaking from cast iron cookware to different types of dishes. What is quite evident is that the iron content after cooking in cast iron increases up to several times in dishes(especially acidic ones)
However, even in the case of significant iron enrichment of food, the total iron amount to which you may be exposed from dishes prepared in cast iron is probably below 45 mg of iron per day(US National Institute of Health) and far below a few hundred mg of Iron that has been reported to cause more significant adverse effects in individuals from Subsachara region.
Just below you will find the table with different ingredients and their Fe content before and after preparation in the Cast iron
(The cooking time/temperature?)
So as reported by Scientists from Texas Tech University the amounts of Fe can go up to 5-7mg/100g of food cooked in cast iron, when it comes to acidic sauce(7).
Additionally, the report from the Research group of Diego-Quintes and collaborators has confirmed the increase of Fe content from less than 1mg to 6.5mg/100g in the acidic sauces cooked in cast iron(commercial tomato sauce)
It will be important to notice that the studies on Fe leaking have been done on seasoned Cast iron cookware and that the non-seasoned cast iron probably leaches more Fe to the food. However, even if non-seasoned cast iron will expose us to a few times higher doses of Fe compared to seasoned ones the final Iron intake will be far below doses that showed to cause serious health effects.
In the end, the final piece of evidence that cast iron cookware doesn’t present a high risk of iron poisoning are studies done on the use of cast iron for increasing the iron content in blood and fighting anaemia(disease related to lack of Fe in the body).
As reported in one bih scientific review on this topic, existing results are too ambiguous to bring the solid conclusion that the use of cast iron cookware can increase Fe levels in the body and help with treating anaemia at all(8.1.).
1.2. Is seasoning on Cast iron harmful for health? Are the black residues on the cast iron surface harmful when ingested?
Main conclusion: It is highly probable that oil degradation products coming from cast iron seasoning and repeated heating of oil resides on a cast iron surface, leads to forming of oil degradation products that may be harmful to health. Even though there are no direct studies investigating oil degradation related to seasoning and cooking with cast iron, many studies demonstrated that exposing the oil to high temperatures and repeated heating of the same oul amount leads to the generation of well-known toxic products such as aldehydes.
Now, lets dig deepr into answering of this question.
Generally, the oil degradation products may include molecules such as hydroperoxymonoenes (HPMs), conjugated hydroperoxydienes (CHPDs) or aldehydes that are provenly harmful to health. Ven none of the scientific publications studied the creation of such oil degradation products during seasoning, numerous scientific publications describe the appearance of such molecules In deep and shallow frying with oils and fats where the temperature variations are less extreme than n the seasoning process.
In case you have been thinking about starting to use cast iron or you have used it in the past you probably heard about seasoning.
Shortly saying, the process of seasoning cookware comprises of heating the oils on the utensil surface to a high temperature which initiates the interlinking between the fat in the oils. Finally, these interlinked molecules create a layer on the cookware surface that acts as a nonstick film. (see the illustration )
However, what nobody discusses is the harmful effect of the oil-heating byproducts created during the seasoning. At such conditions, fatty acids not just interlink and create the nonstick layer but also degrade and produce molecules that are known to be toxic to humans.
In the last several years I tried to learn all that I can about the changes in the oils and fats during the heating process. However, the fact is that most of the scientific papers are turned into studying the fat and oil changes during the deep frying process.
Maybe a handful of scientific studies went in the direction of oil and fat chemical changes in the context of shallow pan frying where the temperature transitions are much faster and more extreme than in the context of heating large oil volumes during deep fry. (8.2., 8.3)
However, best of my knowledge there are no scientific studies about the intensity of chemical transformations and fats during the cookware seasoning process, and potential byproducts created apart from polymerized fats.
Compared to deep and shallow fry, seasoning of cookware exposes the oils to even higher temperature extremes and thus leads to the creation of more products lipid degradation products.
Because of this lack of scientific literature, I have been putting aside the topic of health effects caused by the seasoning process and by molecules that derive from it. However, In the last period, I started to dig deeper into this subject more and more. Moreover, one of the first questions on my mind was:
What are potentially toxic molecules coming from heating the oil or Fats?
After exposure to the temperature oscillations oils and gats fats break down and oxidate. Through this process creates a wide group of components called Lipid oxidation Products(9)
Primary LOPs(the first set of molecules that derive from the oxidation of intact lipids) include highly toxic hydroperoxymonoenes (HPMs) coming from monounsaturated fatty acid peroxidation and hydroperoxydienes (CHPDs) from polyunsaturated fatty acid peroxidation. (10.)
Finally, at high temperatures (ca. 180◦C), commonly applied for seasoning and even for frying, these primary degradation products decompose even further to secondary LOP compounds.
Some of the examples are volatile aldehydes which show a wide range of deleterious toxicological actions if they are inhaled or dietary consumed (10, 11, 12)
However, if you come to the impression that heating is the only factor related to seasoning that accelerates il degradation, unfortunately, I need to tell you that there are more.
Another important contributor to lipids degradation is the repeating of the heating-up and cooling-down cycles as concluded by many scientific studies(13, 14, 15). This is why the reuse of oil for deep frying is widely criticized.
However, imagine now the use of cookare that requires seasoning such as cast iron or carbon steel. What is usually recommended with seasoned cookware is that it should be always covered with oil. Moreover, the common cleaning practice of cookware like cast iron doesn’t include the application of water or soap but the using a kitchen towel to remove food residues if case they stay.
Such practice is something that I was also sticking to earlier. However, mentioned cleaning method constantly leaves some amounts of oil on the cookware surface that is exposed to heating over and over!
So not just that the initial heating up during the seasoning process exposes the oils/fats to extreme conditions and degradation, but also every subsequent cooking stimulates even further degradation since used oils and fats are usually cleaned without water or soap.
Unfortunately, as mentioned there are no studies about transformations of the fat in seasoned cookware up to a day(to the best of my knowledge), so I can’t reference my constatations about the health effects caused by the seasoning of cookare.
However, based on all of my knowledge about chemistry coming from my Bachelor, master’s and now PhD in Biological and Chemical sciences and engineering I am concerned that cooking in seasoned cookware can be one of the most extreme examples of a cooking process that leads to degradation the cooking oils and fats and exposing us to toxic oil oxidation products such as hydroperoxymonoenes HPMs), conjugated hydroperoxydienes (CHPDs) and aldehydes.
So what we can do about this? Is seasoned cookare safe?
I am still using my cast iron and carbon steel cookare and I believe that a change in the cleaning practices can help with reducing or eliminating the potential hazards coming from oil or fats transformation during seasoning, and repeated heating-up processes.
Moreover, I will write more about it in one of the following chapters about Which practices to avoid with cast iron to keep it safe?
1.3.Is cast iron lead-free?
In blog posts around the internet many times I have found the constatation that lead is not added to Cast iron, or because it won’t bring any benefits to the cast iron alloys and it has a lower melting point than iron
But can we really make such conclusions straight away? Is it cast iron in reality lead-free?
Main conclusion: Cast iron utensils can contain lead. Lead may enter cast iron cookware production through recycled iron, which is commonly used as a raw material source. Moreover, some of the published scientific studies reported the leaking of lead from cast iron utensils in amounts higher than the release limits adopted by leading Health authorities such as the Council of Europe.
Nevertheless, let’s first figure out why lead is added to iron alloys in some industries and how it potentially finishes in the cast iron cookware at the end. Then, I will give a summary of some of the scientific studies that reported lead contamination and leaking from cast iron cookware(You can also reach this part of the post straight to the link).
Lead is in general added to steel and iron to improve the ease with which material can be cut and shaped. Such properties of lead-containing iron alloys increase the speed of production and lower production costs.
Just below find the citation of Bossard Group, a leading global provider of product solutions in industrial fastening about adding the lead to the iron alloys(like steal), and alloys of other metals(16):
Modern steel, copper, and aluminium alloys use small additions of lead to improve machinability. The term “machining” of metal covers several operations, including drilling, boring and turning, but generally involves cutting the material towards the desired final shape and size.
More precisely, in the context of iron alloys like to steal they point out:
“Free machining” steels (also known as free-cutting steels) contain small additions of lead (up to 0.35% by weight) which form insoluble globules of metal in the steel. These make the swarf break off into small pieces during machining. Friction and wear on the cutting tool are reduced, allowing higher feeds and/or speeds.
Moreover, as reported by the same enterprise the Lead additions are reported to increase machinability by 30%, allowing higher cutting speeds and 3-5 times longer tool life, and so increasing production rates. This also improves the surface finish of the machined material, and the machining consumes less energy and is quieter.
So in summary, lead makes iron alloys to be easier to cut, which increases the speed of production, increases the life of the tools that cut steel and thus makes the production much more efficient.
Now you may think..
..alright the lead may be added to the steels to improve the easiness of their cutting and shaping. But are not the same thing as the cast iron( cast iron refer to iron alloys that contains over 2% carbon, while steel alloys of iron contains less than 2% carbon) . So the previously referenced information doesn’t indicate that the lead is added to cast iron cookware alloys explicitly?!
In the end, even if adding of lead to some iron alloys may be useful adding it to cast iron cookware material won’t help with anything, since during its there is no mechanical cutting or shaping of the material but instead the liquid cast iron alloy is usually pored and shaped inside of the molds.
And what I would say on this is that you will be perfectly right, this is the same kind of reasoning I was having at the beginning. However, the story doesn’t finish there.
Even if there are no functional need to add lead to alloys for cast iron cookware, the lead is added to other iron alloys In general which may finish as a part of raw material for cast iron cookware as it was mentioned at the beginning of the chapter.
And do I have some information that may reference this claim? Keep reading further..
the website of the Lodge one of the iconic cast iron producers, explicitly say that one of the raw materials for their cookware is a recycled steal:
"We add a mixture of pig iron, recycled steel, castings from our foundry, and alloys to the electric induction furnace. This furnace runs over 2,000 degrees F and it can hold 10 metric tons of liquid iron”
I just hope that one day they won’t remove this from their website, so you could not directly see the reference, since I am not allowed to take screenshots of such websites without permission.
And to make it clear I am not stating that lead finishes up in the Lodge cast iron cookware(I don’t have any reference or proof to state that). Moreover, their cookware is passing a rigorous certification, since it is also sold on the EU market(see my in-depth post about the cookware safety regulations In US and EU)
Moreover, I just wanted to point out that recycled iron alloys can be used as raw material for cast iron cookware, which may lead to the existence of lead as an impurity in the final cast iron cookware products.
Finally, I want to mention that all of the information and conclusions I made in this heading are the result of my research about how lead can enter cast iron cookware. However, it does mean that there are no other ways and reasons for lead to be present in cast iron utensils.
In the end, whatever the reason for lead to be found in cast iron, lead leaking from cast iron was confirmed by some of the scientific studies in the previous past years whatever was. Let’s jump into more details as a part of the following chapter.
Are there scientific studies that confirmed the presence of lead in cast iron cookware?
One of the recent studies From the Korea University in Seul examined the leaking of five metals(including lead, cadmium and arsenic) from different cookware types. Moreover, cast iron cookware was one of them.
To simulate the contact with aqueous, acidic, and fatty foods the utensils were exposed to contact with water, 0.5% Acidic acid or n-heptane(the simulant of oily food), while the leaking of 5 metals was followed. In the case of cast iron pans the study applied the the contact with mentioned liquids for 4h and at a temperature of 100C before measuring the level of leaked metals.
In the end, the study concluded that there is a leaking of lead over the specific realise limits(SRLs) defined by the Council of Europe in cookware pieces tested( SRLs are also known ( SRLs are also known as the maximum permitted amount of a given substance released from a material or article into food or food simulants.) .
In the conclusion of the study, they stated:
“However, for the Cu alloys and cast iron, the release levels of As(Arsenic) and Pb(Lead) exceeded the SRLs, and the release levels of all toxic metals exceeded the SRLs under acidic conditions.”
Moreover, bellow, find the histogram the Lead leaking from Cast iron cookware to water, acid solution or oil -With dashed line presnting SRL limit
Moreover, the study has indicated that Pb release from cast iron may be independent of the fact that cast iron is seasoned(oiled) or not.
“Oiling the food contact surface of the cast iron samples reduced the release of toxic metals, except for Pb, into the acidic food simulant”
Now you may say, ok but the study was using cooking time for 4h with acidic food simulant(water with 0.5% acetic acid) in cast iron, who is, in reality, using such cooking practices? Moreover, what have been the models of the cast iron cookware tested? What were the manufacturers?
And I would agree with this, these would be the limitations of the study presented.
However, if the study confirms something, then it is the presence of lead leaking even from cast iron cookware that is used in developed countries such as South Korea today.
And to make more solid conclusions than this, there will be a need for further independent testing of cookware(Independent from the company tests) and studies.
However, this may leave you also with one important question, and it is how to protect yourself from potential risks of using cast iron cookware like lead leaking or some previously men. Which cookware to avoid or take?
This will be the focus of the next chapter.
2. Which practices to avoid with cast iron to keep it safe?
Through the previous chapters in this post, I tackled some of the main concerns around cast iron cookware.
Even drawing solid conclusions about cast iron safety was not easy, some of the information referenced earlier in the text make a strong suggestion that using cast iron cookware under certain conditions may not be safe.
Led by the information and conclusions I presented to you in the previous chapters I have changed the ways I use cast iron for cooking and I wanted to share it with you.
So which practices to avoid with cast iron to keep it safe? Let’s start with a short answer
To keep cast iron safe it is important to avoid dry cleaning of cookware. Instead, it is recommended to use water for cast iron washing after each cooking. Such practice increases the removal rates of oil-degradation products coming from the seasoning process and heating the residual oil on cast iron over and over. Additionally, to avoid heavy metal leaking from cast iron, which may occur as reported by scientific studies, avoiding cooking practices longer than 1h can be a good precaution.
Now let’s go into more detail about where these recommendations come from and how exactly to apply them to reduce the chances of exposing your health to risk because of the use of cast iron cookware.
2.1. Proper washing of Cast iron
As explained more in-depth in Chapter 1.2, seasoning the cast iron and heating the residual oil on the cast iron surface(If it is not removed) over and over can potentially generate. As reported by many studies exposing oils or fats to repeated heating up leads to the production of toxic Lipid oxidation products (See Chapter 1.2).
So how to remove or minimize the amount of such molecules? The explanation may be easier than it looks. Use the hot water.
Intact lipids(Oils or fats) don’t mix well with water, however, when the lipids degrade under heat they usually oxidate and become more polar. This makes them more easily dissolved in water.
Even though many cooks will recommend dry cleaning of cast iron whenever possible(e.g. with kitchen paper or towel), the better practice seems to be to apply hot water and a soft sponge after every cooking. (Finally, it will be important to dry the cast iron after washing it with a paper towel and by leaving it for 4-5min on the stovetop under low heat).
Finally, the application of hot water and soft sponge won’t remove the nonstick coating created on your cast iron pan, since this coating is formed from polymerised fats that have low solubility in water. Nevertheless, such practice will potentially minimize the amount of lipid-oxidized products that are more soluble in water(The more they are degraded and oxidized, they usually get more soluble in water)
As an additional tip always use the soft side of the sponge since the abrasive side may damage the coating, at least from my experience.
It is hard to spot these scratches on the cast iron surface since it is black and sometimes quite porous. However, on carbon steel, it is quite easy to see the damage to the coating that can come after using the abrasive side of a sponge.
2.2. Choosing the cookware with the proper safety certification?
One question that naturally comes first in regard of this topic is which kind of certification is the best guarantee for cookware safety?
The cookware safety regulations in the US seem to have some important omissions while the EU standards push the cookware producers to quite rigorous testing, especially in counties like France and Germany(See my in-depth post about the US and EU cookware safety regulations and testing here).
Because of that choosing cast iron cookware from brands that sell their products in France and Germany can be a good starting point for having confidence in the safety of the products you use.
Cookware sold on the French and German markets needs to pass EU regulations EC1935/2004 and EC2023/2006, as well as some important national regulations of these two counties. An example of a cast iron company that sells products in both of these markets is Lodge.
This is one of the biggest brands on cast iron cookware market, and the brand that I personally use (you can see my summary of about cast iron from this brand here).
Here is one of the frittatas that I love to make in my lodge skillet.
However, this doesn’t mean that some other brands that are among others sold in the French and German markets, among others are not good choices in terms of safety and performance. So, If you are searching for a good counterpart to Lodge, Camp Chef cast iron can be an option to look for.
Even though I haven’t tried it before, it is a brand having a lot of good reviews from customers around the world.
Finally. You may ask but what about the vintage cast iron cookware? Does the thing you said mean that it is not a safe option to use?
Many people are interested in vintage cast iron, and it is a huge market that includes some high-quality products. However, from my perspective, these products usually haven’t passed any safety certification.
Finally, the origin of the raw materials used for cast iron in the past may vary a lot, and the only secure proof that they are safe to use(e.g. not contaminated with heavy metals) is individual testing of each piece. However, without this individual testing, I won’t personally use them by myself (and for sure many people won’t share this opinion with me)
2.3. Avoiding specific cooking practices
As mentioned in Chapter 1.3. It has been reported by the studies that some cast iron cookware pieces may contain residues of heavy metals. Moreover, it was demonstrated that during some cooking practices, these residual heavy metals may leak from cast iron cookware (both seasoned and not seasoned) in amounts higher than ones prescribed by world health authorities( Chapter 1.3).
As mentioned in the previous chapter, cookware safety certification is a good starting point to prevent the chances of having cast iron that leak heavy metals into your meals.
However, in my opinion, safety certification only reduces the chances of having traces of heavy metals in your cookware.
Companies may test the cookware for heavy metals leaking just after production, but this does not need to be a guarantee that cookware won’t leak traces of heavy metals after some time of use.
So which cooking practices will be good to follow to additionally minimize the chances of being exposed to heavy metals from cast iron?
The simple rule to follow will be to avoid cooking food for a few hours in your cast iron pan, or living it in the cookware at night. You may now ask, ok what exactly mean a few hours? Is it 2, 3 .4, or more hours? Unfortunately, there is no solid line.
The best that I can say Is that most of the studies that have reported the leaking of metals in the amounts over the ones prescribed by world health authorities were exposing the cookware to 1h, 2h, or more before measuring the metal leaking.
An example can be the earlier mentioned study from the University of Korea in Seul(17), where they find reported the leaking of several metals cast iron, but also other cookware in amounts over the prescribed limits. In this study, they use 2-4h of cooking process.
Another good case can be a study on leaking of the Nickel and Chromium From Cast iron which also showed the leaking of these metals over the limits, but they also have been using the cooking process for more than 1h (18).
These are just some of the examples of scientific research, but up to now I still haven’t come to a relevant study showing the significant leaking of metals(including heavy metals) after the cooking process of 20 min or 30min. (I don’t say that such a study won’t be published one day, I just say that to the best of my knowledge up to now I don’t know of any relevant scientific study with such results).
So The rule of thumb that I use, is to avoid the cooking processes over 1h in the cast iron.
*Finally, Just to clarify what I mean when I say relevant scientific studies(Something I also repeated a few times in other articles on Safetouseit). Not all of the scientific literature is correct, and it is very important to take every scientific study with a reserve before seeing the exact methodology and analytical approaches they use before saying if their conclusions are valid.
E.g. There were some scientific studies that wanted to estimate meatal leaking from cookware by using metal chips as a simulation.
Some of them showed metal leaking that may be significant for health even after exposing the metal chips for 20 min or 1h to the acidic sauces under high temperature and concluded that the same happens when cookware comes in contact with food(18).
However, I don’t agree with this type of reasoning, and would not take these studies as relevant.(If you have doubts about the conclusions I draw based on any of the scientific references I share in this article feel free to write to me and I will be happy to provide you with more information)
3. FAQ about the Cast iron cookware safety
Finally, under this chapter, I am listing answers to other questions that you might come to regarding cast iron cookware safety. Moreover, in future updates of the article I will potentially add more of them, so don’t hesitate to send the questions you have about this topic directly to me, or put them in the comments. That way I can potentially cover them in the future.
3.1.Is cast iron Safer than non-stick?
Cast iron is safer compared to nonstick cookware based on Teflon. Unlike Teflon, Cast iron does not bring the risks of nonstick coating degradation at high cooking temperatures that may be commonly used in daily kitchen practices.
Generally, Teflon-based non-stick cookware is problematic in the first place because of the release of toxic fumes. Moreover, these toxic fumes may be released even at temperatures lower than 260C, as it is commonly recommended as a limit for Teflon product use.
In my article about granite cookware, which is contrary to common beliefs usually made from Teflon, I summarized more about the scientific study’s conclusions on what temperatures cause the risk of Teflon degradation.
Moreover, in the same article, I discussed more in detail the scientific evidence for other health concerns of Teflon-based nonstick cookware.
4.Safetouseit long-term perspectives
In the end, I need to say that cookware certification(even when provided by countries with rigorous standards such as France and Germany) will not be the absolute proof of cookware safety, but just reduces the risks of using non-safe cookware.
The best will be if more and more independent cookware safety testing will exist apart from the information provided by companies and the government.
As mentioned, when cookware is passing e.g. the metal leaking tests before entering the market, the new pieces of cookware are the ones tested and the ones which need to pas the safety tests. But how says that in some cookware types, the leaking of metals won’t increase after half year or year of use.
Because of this, the deep aim and long-term objective of Safetouseit is to become an independent platform for the safety testing of cookware and kitchen items.
Nowadays I work on a PhD in science, and I have access to performing some of the cookware safety analysis by myself. One of the first steps that I see for the future is testing the leaking of heavy metals from various cookware brands on my own and underlining more solid conclusions.
In the end, as a longer-term goal, I aim to grow Safetouseit enough so it will be capable of investing In independent testing of cookware safety in different laboratories that provide such services and providing more answers to the world. So stay with Safetouseit in the upcoming months and years and I believe there will be many things to share among us.
