It should be kept in mind that almost any material used in contact with food will leach something, especially when it is used during cooking, i.e. at high temperatures, and, in the case of metals, when the food contains fruit juices or vegetable juices, which are acidic.
So what matters is the hierarchy of the materials from this point of view, i.e. which are better and which are worse.
The best material for food-contact is glass, but glass, while perfect for storage, is not suitable for most types of cooking (even if it is quite possible for someone to eat only food cooked in a microwave oven, in glass cookware).
The next best material is titanium (commercially pure titanium, not the frequently encountered Ti-Al-V alloy). Titanium cookware exists, but it is normally too expensive, unless it is used in some activities where its low weight can justify the high price.
After these 2 cookware materials, which unfortunately are not an acceptable choice for most people, comes the stainless steel.
Yes, stainless steel will leach a little nickel and chromium. However this leaching will be large only for new cookware and it diminishes a lot for used cookware. Even in the case of people with nickel sensitivity, most of which are women, the quantities of nickel leached from used stainless steel cookware are far too low to have any effect.
All the other materials that are used for cookware, including ceramics, can be sources of much more dangerous leaching than stainless steel (excluding glass & titanium).
Ceramics and plastics are the worst (this includes any non-sticking coatings), because, unlike for metals and glasses, their chemical composition is usually kept secret by their manufactures, so you never know what they may leach.
The distinction you're trying to draw between glass and ceramics doesn't exist, ceramics are generally glazed, which means "covered in a coating of glass".
Enameled pans aren't going to leach anything if you buy them from any reputable manufacturer (which is at least all of the European, American, and Japanese ones) because any colorants added to the glaze will be rated as food safe. In fact, you mentioned titanium: that's what's used to make the inside of white enameled pots look white.
Enameled cast iron (or enameled anything) is a fine choice, it comes with its own limitations culinarily (and advantages) but it isn't going leach anything into your food.
Nevertheless, most glazes have a much more complex composition than the standard borosilicate or soda-lime glasses.
Glazes usually contain colorants and various additives that improve certain properties useful during manufacturing, which do not exist in the glasses used for vessels.
It is possible to make glazes that are perfectly safe for food contact, but historically there were many examples of glazes with harmful components.
Unless a manufacturer provides the composition of the glaze used by them, you cannot know how safe it is.
Moreover, glazes and enamels have a problem that does not exist for stainless steel vessels. The glazes or enamels may crack and expose the base material to the food. However that is somewhat mitigated by their lower price, which facilitates the replacement of the cookware.
> 4.8 Specification and determination of the release of toxic elements
> The specification and determination of the release of toxic elements must comply with the requirements specified in the national laws of the country.
Most of the other requirements are about the mechanical properties of the enamel.
There's also this:
> 4.32 Determination and control of Lead and Cadmium release for hot water tanks
But that doesn't apply to cookware.
There's nothing here about requirements for the composition of the enamel or the making public thereof. And what constitutes a "toxic element" (and presumably the dosage) is left to the laws of each country. Most of these countries would consider stainless steel to meet their leeching requirements as well. So we're back to square one. There's no way to tell what the enamel is leeching. You just have an assurance that it's considered safe.
>Enameled pans aren't going to leach anything...because any colorants added to the glaze will be rated as food safe
So we consider stainless steel pans as food safe generally, yet they do leach something. I don't see how food safe could imply that something doesn't leach. Only that we either think it doesn't leach too much or we don't think what it leaches is harmful.
Sure, if you buy used enamel you can even get uranium. Which looks lovely but I wouldn't cook tomatoes in it.
This is why I specified "buy from a reputable manufacturer" because there is no risk of this whatsoever if you get contemporary / new cookware from the indicated regions; that list isn't exhaustive but I stand by this: any cookware you buy new from EU, America, or Japan, will not contain lead in the glaze, or anything else you wouldn't want to eat very small amounts of.
I heard that even well known brands like Le Creuset pots have lead in the ceramic coating on the outside of the pot. I guess that's not the same as being on the inside. But still, that seems not ideal.
>Enameled cast iron (or enameled anything) is a fine choice, it comes with its own limitations culinarily (and advantages) but it isn't going leach anything into your food.
Has this been verified in practice? Is enamel always pure, or can it contain contaminants that can leach?
> Ceramics and plastics are the worst (this includes any non-sticking coatings), because, unlike for metals and glasses, their chemical composition is usually kept secret by their manufactures, so you never know what they may leach.
It is not clear from the advertisements of the vendors what kind of material is used for the so-called "ceramic" coatings.
I believe that they use the word "ceramic" to say that the coating is not made from an organic polymer, like Teflon, but from an inorganic oxide or mixture of inorganic oxides.
The correct meaning of ceramic is a material that before processing is soft and plastic, so you can give it any form you want. Then, after heating at very high temperature in an oven, a.k.a. burning, the finished ceramic product becomes hard.
I am pretty certain that this is not how the so-called ceramic coatings are made.
The cookware that I have seen with "ceramic" coatings had bodies made of aluminum. So I assume that the "ceramic" coatings are mostly of aluminum oxide, probably grown electrolytically or chemically.
True ceramic products consisting mainly of aluminum oxide are very common, so I assume that this is why the "ceramic" coating vendors use the word "ceramic".
Alumina, a.k.a. aluminum oxide, is inert enough in most conditions to be safe for food contact, even if not as safe in contact with acidic juices as glass.
As always, the base material is less concerning than the possible existence of undisclosed additives.
It is possible that the so-called "ceramic" coatings are perfectly safe, but nevertheless I would not buy one unless the vendor would state clearly the composition of their "ceramic".
I have seen too many contrary examples in the past, so that I cannot trust anyone who says "Trust us, it is good for you", without providing additional relevant information.
And nonstick coatings can also off-gas and be damaged or deteriorate over time.
My big thing about this study is that they claim to use realistic cooking parameters. Some dishes may be cooked 6-20 hours, but how common is that? Wouldn't most dishes be under 1 hour and contain less acid? Seems like they're targeting worst case scenarios, which are plausibly realistic but not typical.
Did we skip cast iron? Iron leeching into your food is actually a good thing. There are several brands of excellent cast iron cooking products which should be safe. Staub is one I like.
I love my lodge pans. If you properly clean and oil them, they are as easy to use as non-stick alternatives. For a long while, I didn't believe this, but then I used my parent's pan one weekend, and it was a revelation. Turned out I'd never properly seasoned / kept my pans seasoned.
Can you point to good a guide on how to use cast iron effeciently. I have been trying to use cast iron more regularly but end up getting frustrated. I feel like I am not taking the right steps to keep it seasoned. Whenever I cook food gets charred. For context, I do most of my cooking in non-stick cookware.
The non-stick properties of seasoned cast iron are a bit overstated. Yes, its a lot better than stainless steel, or unseasoned, but any number of foods (eggs) will stick regardless of how much oil you add ahead of time. And unlike some of the nonstick coated pans, you always need at least some fat/oil in them during cooking.
So some of it is what you expect, cast iron is basically non stick for lots of things (AKA I would never use anything other than cast iron for pancakes/etc), but I keep a couple Henckels Capri Notte Granitium pans we picked up at cosco handy for the morning eggs. Those seem to be the survivors at this point of a long series of trial and error with non-teflon coatings, most of which seem to work fine for a month or two and then are non stick at the same level as one might expect from cast iron. I have no idea how much I've spent buying pans a few times a year at $20-50 a pop to replace worn out nonstick over the past 10 years.
I wash my cast iron pan after each use, sometimes just with very hot water and sometimes with a little soap if I need it, but I always thoroughly dry the pan and do a quick re-seasoning afterwards. This is just a quick wipe down with a paper towel with a dab of oil on it, and I leave it on my stove top with the (electric) burner on low for about 30 minutes.
A good tip I read is to wipe down the pan with such a thin layer of oil that it's as if you made a mistake and want to remove the oil with just the paper towel instead. It should really be as thin as possible, and you'll see it sort of glaze over as it drys on the stove top. After about 6 months of this, using the pan about once a week, it has been truly non-stick for a while.
After a lake vacation in western NC, I stumbled across my first Griswold Cast Iron pan. The bug hit me and I've collected a couple of others since then. My favorite so far is the Colonial Skillet Griswold 666 (aka Satan's Helper). Makes an amazing mix of eggs, potatoes and bacon. I started looking up the best way to season these pans and found [0] and [1] very insightful.
It’s often helpful to sand & polish cast iron skillets before seasoning them. You just have to take precautions so you don’t inhale the metal shavings. Here’s a good reference: https://youtu.be/2wHZ7hKpPUs
Also, the type of oil you use to season your cast iron cookware is important. You should use flaxseed, grapeseed or avocado oil. Do not use olive oil, because it has an extremely low smoke point. Canola and vegetable/soybean oils are unhealthy.
There are million anecdotal methods on how to care for cast iron, but this TL;DR works for me: Use some kind of oil when you're cooking. Hand wash them and never put them in the dishwasher. And coat with a thin spray of olive oil (the "oil only" sprays are great) after use and buff with a paper towel. Never leave anything on the iron surface except a light coating of oil. Don't let them air dry. That works for me! :-)
Any kind of iron cookware leaches in food a quantity of iron that is many orders of magnitude greater than all metals leached by stainless steel.
Fortunately, excessive quantities of iron in food are not dangerous for most people, even when the quantity is great enough to give an unpleasant taste to the cooked food.
In any case, iron cookware is preferable to ceramic/plastic/non-sticking cookware of unknown chemical composition.
About enamel, that is a complex mixture of various oxides.
All colored enamels have undesirable components.
White enamel can be made perfectly safe for food contact. Unfortunately, being white is not a guarantee for that.
Manufacturers are tempted to include in the enamel composition various oxides that improve the manufacturing properties, e.g. which increase the fluidity of the melted enamel, or which enhance the adherence of the enamel to the base metal, and so on. These additives may leach unwanted substances.
So one may use cookware with white enamel, if they trust that the manufacturer was not too greedy to reduce their costs.
Ideally there should be a law to force all manufacturers of cookware to publish the precise chemical composition of any material used for food contact, like there are laws for labels with the approximate food composition.
Until then, it is safer to distrust any kind of coatings, plastics, enamels or glazes with secret compositions, because in the past there were many bad surprises whenever any of these were analyzed.
I like the way you think. If you have a pan made of food, does it matter if some food leaches to your food? For a person with iron deficiencies it's hard to argue additional iron is bad, however...
Once your iron gets into contact with oxygen, you will no longer consume iron, you will consume rust...
Actually what you need in your body is rust, i.e. iron ions.
Metallic iron cannot be used in any way by living beings, before it is oxidized to rust.
The leaked iron from cookware is already in the form of "rust", more precisely the iron is leached after it is oxidized to iron ions. The ions with 2 elementary charges remain dissolved in the water, and they may be absorbed by the body, while the iron ions with 3 elementary charges (these are the components of rust in the strict sense, i.e. of red iron oxide) will normally precipitate into red rust crystals, which will pass through the digestive tract mostly without being absorbed (a few might be reduced to ions with 2 charges, and then be absorbed).
I am not an expert but it seems that the form of iron absorbed by human body is ferrous sulfate, iron in +2 oxidation state. Iron rust of iron pan is in +3 state, which is chemically a different thing.
The issue with iron cookware (and I'm a big fan) is cooking acidic dishes in them (which are the ones that mainly cause the leeching) you destroy the seasoning and they become a bit of a pain to clean after that.
A little bit of carbon (2-4%) and silicon. Otherwise it's just iron.
It should also be noted that with a properly seasoned cast iron pan, the food isn't interacting as much directly with the iron, since the seasoning layer (polymerized fats) is in the way.
Pure ceramic is porous, so it is never used in direct contact with food, because the food will be absorbed in the pores.
In all cookware where the body is ceramic, the surface is covered with some glaze, enamel or plastic coating, which is the material that really counts for food contact.
You are right that unglazed pottery had been used for many thousands of years, before glazing was invented.
The information about soaking is interesting.
I was not aware of it, because there are many countries were unglazed pottery is no longer used, at least I have never seen any of it used for food contact, but only for different purposes.
> The problem with modern Teflon is mostly that people overheat their non-stick pans
Also using metal or other "hard" implements in those non-stick pots/pans, which damages the non-stick layer allowing it to flake away into the food prepared in it over time.
If someone responds that a material is 'chemically inert' when we're talking about heating things up, I don't think I'd have much confidence that it's not leaching into my food.
Not quite. Off-gassing begins at a bit under 400F. And the assumption that it's "really tough" to reach either temperature (400 or 500F) is wildly incorrect for the realities of cheap stovetops around the world. Gas / propane is widely used and can cause teflon to begin smoking within a minute or two.
But yes, it's probably fine on your fancy glass induction stovetop.
I'm not entirely convinced that plastics are categorically bad. I suspect they are better than stainless for long term storage of certain things.
There's a lot of plastics that don't commonly get used but are food rated in industrial applications, it would be cool to see them thoroughly evaluated and if they are safe, made into consumer items.
Ceramics are scary because a few have lead in them, but there are safe ones(Just not that you can afford), they're used for surgical implants.
I wonder what the possibilities are with magnesium. It can be extracted from the ocean and is nontoxic enough to just put back where you found it, so it seems to be the closest we have to a renewable metal.
There's also laser etched lotus effect patterns. Do metals still leach after you make them hydrophobic like that? Could you make magnesium corrosion resistant enough?
The base components of many plastics, e.g. polypropylene, polyethylene, acrylic glass, are perfectly safe for food contact.
The problem is that all plastics contain various additives, which are normally not disclosed by the manufacturer, even in the plastic grades that are approved for food contact.
The risks caused by unknown plastic additives are especially large when the plastics are used above room temperature, e.g. for heating food in a microwave oven.
Storing food in polypropylene vessels or polyethylene bags in a refrigerator is likely to be perfectly safe.
Irrespective of safety, plastic fares poorly for me for taste reasons. Most soaps and detergents contain fragrances that seem to persistently bind to plastic food containers. The exception are soap products like Seventh Generation, which seem to contain less harsh/”natural” fragrances, which don’t seem to be as persistent. As it is, most foods stored in most plastic containers washed by most
soaps taste like soap to me. For this reason alone, I avoid plastic where possible.
No competent chemist could have ever thought that BPA is a safe substance.
Some chemists have believed that the risks of depolymerization for the plastics that are made with BPA, e.g. polycarbonate, are low, so the risk of BPA leaching into food is low. However there have always been many chemists who have believed that the risks are too high for any such plastic to be considered as safe for food contact.
The problem is that the relevant true experts are almost never consulted for decisions regarding the use of materials for various purposes. Those who are consulted have usually very narrow specializations and can have informed opinions only about a part of the relevant criteria. The final decision about the use of materials is usually done strictly by financial criteria.
Some chemists have found a method to make polycarbonate, a plastic that combined useful properties, like high transparency and high impact resistance. They did not think about which are good uses for it and which are bad uses for it, it was not their job. Then someone else has developed a cheap method to make bottles out of it, also without giving much thought about what is suitable to be stored in such bottles or not, it was not their job. Eventually someone else has decided to fill PC bottles with some beverage and sell them.
The error has been at the end, because any material used for food-contact should be scrutinized much more than for almost any other purposes. There already are laws and regulations about materials for food-contact, but they are neither strict enough, nor applied correctly most of the time.
While there have been many problems with plastics used for inappropriate purposes, there are a lot of similar examples with all kinds of materials, crystal glass with lead used for many centuries (fortunately only the rich could afford it), silver-mercury amalgam used in dentistry for more than a century, uranium glazes and many others.
We can only learn from past mistakes and improve the existing legislation.
In my opinion, the most important would be a law forcing any manufacturer to publish the exact chemical composition of any material that is used for food-contact in their products.
This actually does not leak any valuable trade secret. Anyone with enough money can make a precise chemical elemental analysis of any object, only individual customers cannot afford it.
The valuable trade secrets are in the details of the manufacturing process, not in the final product, which can be analyzed by any competitor.
Another potential problem with magnesium is its flammability. Look up magnesium fire and you'll understand. Maybe not that likely in most settings (it takes a bit to get it going), but a forgotten pot on a gas burner would worry me.
Also cast iron and carbon steel both leach iron into food. Iron is now known to cause stress to cells and can even initiate a special form of cell death.
Not OP but many people (1 in 300 Caucasians [1]) need to closely watch and minimize their iron intake because they have hereditary hemochromatosis. With hemochromatosis ones body cannot process iron. There is no cure and the only way to deal with it is to minimize iron intake and, if iron levels are too high, blood letting (phlebotomy).
> if iron levels are too high, blood letting (phlebotomy)
A friend discovered a few years ago that he has (developed?) hemochromatosis. From what I understand, in Canada the "prescription" for this is to diligently donate blood to Canada Blood Services, I think more frequently than the general public is allowed to. He's got an awesome blood donation record now!
You can't "develop" hereditary hemochromitosis [1]. It is a genetic disorder. Both parents need to carry specific genes that when combined in the child cause hereditary hemochromitosis.
I don't know about Canada but in the US it is illegal to donate blood when you have hemochromatosis. I get phlebotomy every other month (for the past 10 yrs) and my blood is always thrown away.
I have no clue if his was hereditary or not, I just remember him going to Mexico, feeling funky about half-way through the trip, and his doctor diagnosed it when he got home. Would've been in his 20s.
So this conversation has gotten me to research this topic a little bit more. I'm not exactly sure if it's actually illegal in the U.S., that's just what the nurses who do my phlebotomy have told me. Though I did find that the American Red Cross does not accept blood from individuals who have hereditary hemochromatosis [1].
My case was discovered when my doctor did an iron work-up as part of checking out my liver. The normal level in men is 12-300 nanograms per milliliter (ng/mL). Mine was very close to 1000 ng/mL at the time. These days my hematologist likes to keep me in the 50-75 ng/mL range.
So many multivitamins, etc, omit iron out of fear of iron poisoning, that one can easily err on an individually-deficient side.
(The optimal window also appears narrow enough -- even people with temporary anemia must limit supplements -- that I would not attempt to rely on cookware to supply my iron requirements.)
When I was a kid I noticed that Cheerios are notably high in iron. I threw a bunch of Cheerios into a cup of water and let it mix for many hours on a chemical mixer. The iron fell out and stuck to the stirrer magnet as a small amount of iron filings.
Is this dietary iron different from the iron you get from a pan? Or do Cheerios cause stress to cells and a special form of cell death?
I suspect that that iron is not bio-available and so does not provide much nutritional benefit. To be available for absorption, you want an iron salt such as ferrous gluconate that is soluble in water and can be integrated by cells.
I've always wondered about the patina, or carbonized oil, on my cast iron and carbon steel pans. That stuff leeches over time too, and it's probably carcinogenic? Have there ever been any studies on the seasonings on those pans and any potential health effects?
That being said, I love my pans and probably wouldn't stop using them.
This is not useful information if not combined with the quantities involved. It's like warning that drinking water is known to raise your blood pressure and has even caused people to die of heart attacks. It's true, but not in the quantities a person usually encounters.
Sauteing. Frying. Well, pretty much any stove top cooking.
I mean, sure, if we want to "well technically" the hell out of it, one could probably use glass if you're careful. But one also has to consider safety and convenience.
It would indeed. I know this, because I left a glass casserole dish on a hot stove eye when I was young. A while later it exploded and the kitchen floor was marred with little burns from glass "meteorites " from the explosion. Thankful no one was in the kitchen to say the least.
You can find them on eBay still. I definitely wouldn't use one; they seem utterly impractical. They must be heavy, they are small, and the clip-on, rather than bolt-on handles are going to be rusted and dodgy at this point. You can see why they chose that strategy (to avoid a heat stress point around a bolt) but it can't be without its risks.
I've got a 'flameware' saucepan and it works great. Very light and visually interesting, but I put it away for special because I'm always worried I'll break it. The strap and clip handle is fine on my pan but it does seem like it needs to be tightened up every so often,so I could see it being a common point of failure.
Intuitively I feel like you could probably get away with borosilicate (certainly quartz if just have nothing better to spend your money on) on top of an electric stove.
What bothers me is, people washing and scrubbing their frying pans.
I cook in stainless, and after done just put it in the sink with water. After I eat the food, maybe a half hour later, just dump the water and wipe it with a rag.
Point is, why remove the grease, why remove the seasoned crust on pan. Do people take soap and scrub brush to their bbq too?
You don't need to soap wash, or scrub a frying pan.
This sort of behaviour likely keeps leeching to a minimum, compared to vigorously scrubbing and cleaning each use.
Copper is more reactive than steel. Copper cookware (with some rare exceptions) is lined with another metal to prevent food from direct contact with copper during cooking. Traditionally, a thin layer of tin is used for this purpose, though modern copper cookware can sometimes use steel or anodized aluminum.
I cannot access the full-text of the second article, but is it really thought that heme iron is the component of red meat that contributes/causes cardiovascular disease?
Did the authors somehow adjust for the fact that a high heme iron intake generally implies a diet high in red meat?
So there’s several details and questions that I think might be important for interpreting this study!
1) all stainless steels need to be “passivated” in order to be properly stainless. These days that process involves putting the stainless steel in a hot water bath with like a pound of citric acid for every gallon of water used. (I actually do this at home with any cookware or steel bottles where I notice a metallic taste). Chips of stainless steel that aren’t passivated will leach and or corrode!
2) I think most cookware is 304 steel. I’m not sure how often it’s 316. But also unless you control for passivation it’s still pretty uninformative.
When welding stainless used in food service, you then need to re-passivate all the joints. Can be a bit of a pain for long pipelines. You'll often see acrylic piping used in food plants partially for this reason (another reason is that it's easy to see any blockages or growths etc through the pipe walls).
I don’t know! With citric acid and it’s predecessors, they only dissolve iron atoms but don’t react with the chromium and nickel alloying elements, which is an important combo!
I found this passage. Doesn't really explain the process though.. natural oxidation completes in the air 1-2 weeks?
>To passivate stainless steel at home without using a nitric acid bath, you need to clean the surface of all dirt, oils and oxides. The best way to do this is to use an oxalic acid based cleanser like those mentioned below, and a non-metallic green scrubby pad. Don't use steel wool, or any metal pad, even stainless steel, because this will actually promote rust. Scour the surface thoroughly and then rinse and dry it with a towel. Leave it alone for a week or two and it will re-passivate itself. You should not have to do this procedure more than once, but it can be repeated as often as necessary.
It would be if you made it in space, but in the presence of oxygen, or when the factory dips it in acid which is what they do, the surface is depleted of iron and enriched of chromium to a depth of a few molecules. Below that is a thicker nickel-rich region.
Nobody really knows how this migrating is happening at a low level, by the way. Mystery of material science.
"The inside of the can is lined by spray coating an epoxy lacquer or polymer to protect the aluminum from being corroded by acidic contents such as carbonated beverages and imparting a metallic taste to the beverage."
I'll vouch for that when it comes to beer. It's not just the packaging itself though, but also the experience. Plus, when you drink from a can directly, your lips will touch the outside / top aluminium, which will affect the flavor and experience - subtly, but it's there.
> when you drink from a can directly, your lips will touch the outside / top aluminium, which will affect the flavor and experience - subtly, but it's there.
Ahhh the subtle flavours of rat shit. I've never seen someone wash the top of a can before opening it. I mean, would you go around licking random surfaces that other hands have touched, rodents have scurried over and defecated on, etc?
As an aside, to me Coke from can has a different feel from Coke from plastic bottle. Almost as if the bubbles are fewer and larger when sipping from a can.
Mexican Coke, which uses cane sugar, comes in a glass bottle, but you can also get US coke presumably with corn syrup in a glass bottle and some people do think it tastes better.
Though, it is complicated because there are multiple bottlers making multiple different coke products, and even the same bottlers could shift what sweeteners they use over time, presumably based on pricing.
Just about every disposable water bottle is PET, which is far down the list of dangerous plastics when it comes to leaching (to ignore for a moment microplastics).
If the cans weren't lined (like other commenters remarked), the most the acid in the soda would do is dissolve a little bit of the aluminium - of course that's not necessarily healthy, but to get a hole in the can you'd need something much stronger. Despite what some urban legends claim, there is still a difference between Coca-Cola and hydrochloric acid...
Some browsing lead to this interesting bit of trivia -- nickel means demon or goblin, and originates from miners mistaking the nickel ore for copper ore,
calling it "goblin's copper".
>As early as the 1600s, a dark red ore with a distinct green coating became a notable source of irritation for copper miners in Saxony, Germany. Believing that the dark red substance was an ore of copper, they continued mining it. As the ore was causing ailments, the miners turned to folklore and adopted a belief that it was protected by goblins. This ultimately led to the naming of the ore as “kupfernickel,” translating to “goblin’s copper.”
The -nik in Kopernik (the unlatinised name) is not related to the Koper-: it makes it a agent noun in Polish (and other Slavic languages), similar to beatnik, robotnik and Sputnik. It's basically like "-er".
The Koper- could relate to copper, or dill (says Wikipedia). Then it would be copper-er or dill-er. Maybe his family once coppered pans or ships or made pickles!
Copper in Polish is "miedź". If it was borrowed from a foreign language they would use Latin not English (there's almost no English loandwords in Polish at the time) so it would be cuprum. Or they could use German - so Kupfer. In any case the second vowel would be "u".
So "Kopernik" name is probably related to the dill plant (koper).
Sibling discussions seem to contain a lot of hand-waving. I'd love to know the truth about the safety of stainless v plastic v glass etc but we seem to consistently run into two problems. 1. Chemistry is hard and 2. Biology is hard and slow.
The way we describe chemicals is usually component based and not functional. H2O and H2O2 look similar but water and hydrogen peroxide have radically different properties. One is good to drink regularly, the other deadly. Reading that something contains anionic chlorine might be bad, but then again it might be table salt. For more complex chemicals this gets even more confusing.
Then you take this extremely-hard-for-lay-people-to-parse language and try to use it to predict interactions with a human body. Moreover you really care about not just acute (strong, fast) effects but long term cumulative effects. The article is discussing acute effects for allergy sufferers, but what about 10 years of exposure to small amounts of leached nickle? 20? 30?
The possible number of variations on chemicals, the biological systems they can interact with, and the time/effort required to perform rigorous epidemiological studies for each seems like a herculean task we are ill equipped to tackle. I'd love to be told I'm wrong, but it just seems like any discussion of these topics is not just fruitless but genuinely dangerous as it's possible, given the lack of a credible causative structure, to convince ourselves of anything.
> The way we describe chemicals is usually component based and not functional. H2O and H2O2 look similar but water and hydrogen peroxide have radically different properties. One is good to drink regularly, the other deadly.
I don't think this is a fair characterization.
In inorganic chemistry, the ions do matter. Saying that something contains Fe ions is basically all you need to know; Fe 2+ and Fe 3+ can be easily converted into each other through redux reactions, so distinguishing them doesn't provide value.
If you are honest in your communication, you also distinguish between H20 and H2O2, precisely because they aren't equivalent.
> Then you take this extremely-hard-for-lay-people-to-parse language and try to use it to predict interactions with a human body.
This part I agree with.
Remember the "free radicals" craze of the 90s (or was it early 00's?) Biologists talked about free radicals in the blood being a potential cause of some damage (was it cancer?), and people started to eat food that would bind free radicals, completely ignoring all the chemistry of the digestive system that stands between the food and the blood.
> I'd love to be told I'm wrong, but it just seems like any discussion of these topics is not just fruitless but genuinely dangerous as it's possible, given the lack of a credible causative structure, to convince ourselves of anything.
Basically all research that is published, by its very nature, contributes a small piece of the puzzle. But it's the job of other researchers to interpret that and work towards a fuller understanding, until we have something that is ready for general consumption, both in terms of validating it, and putting it into context.
This is something that we as a society haven't figured out yet. Media loves to report on new science publications, and has a hard time putting the maturity (or lack thereof) and actual impact on daily life into context. But we cannot just blame "the media", we also have to blame ourselves for consuming it.
> I'd love to know the truth about the safety of stainless v plastic v glass etc
I think the only thing we can say with certainty is that things that have been around long enough (like cast iron, clay cooking ware etc.) is most likely safe, otherwise we would have noticed it by now.
> I think the only thing we can say with certainty is that things that have been around long enough (like cast iron, clay cooking ware etc.) is most likely safe, otherwise we would have noticed it by now.
Agree, I think this is the most important part. I think we obsess too much over things that might possibly have some small effect 1% of the time after 30 years or something after you apply a bunch of tricky statistics. Anything that has been used by millions of people for decades, centuries, would have been extremely obvious if it did anything bad.
Worth noting that this investigation specifically analyzes highly acidic tomato sauce and that is likely to be the worst case scenario. Still very valuable research!
Also, it's with factory-fresh steel. Fig. 1(b) shows something like a 10x reduction between the 1st and 6th cooking cycle (discussion suggests there's a passivating oxide layer that forms).
Like those videos of engineers breaking airplane wings at 300% design strain, this kind of paper is more reassuring than scary IMHO.
Yeah, and it's completely bizarre how this paper doesn't even contain the word "passivated". Stainless cookware comes from the factory passivated, because otherwise it would be highly reactive and rust immediately, violating consumer beliefs about the word "stainless". Passivated stainless is virtually all chromium oxide on the surface. So I'm not sure why the paper even mentions the bulk fraction of Cr in 304 and 316 SS.
Stainless steel passivation is a chemical process to remove free iron and contaminants from the surface of stainless steel. The stainless forms its own passive film upon contact with oxygen - it is not added.
You make a good point about the surface primarily being chromium oxide.
Not passivated, but it does mention seasoning. The same thing?
quotes:
>A chromium oxide protection layer is consistent with our findings, NIST160b has the highest Cr content and Ni content, but does not have the highest nickel leaching, suggesting that Cr alone or with potentially other constituents reduces Ni leaching.
> As discussed above the formation of protective oxides, like chromium oxide, likely contributed to the reduction in Ni and Cr leaching with seasoning.
Interesting, though the article doesn't specify exactly what seasoning is, and specifically mentioned "formation of protective oxides, like chromium oxide" with seasoning.
I feel there might be some overlap, or loose use of the terms.
This is a really good thing to know about though. I love my cast iron pan. But tomato sauce is the one thing I still pull out my stainless steel pan for.
So is it better to just use my cast iron pan for tomato sauce too and just live with the fact I have to redo some of the seasoning if I happen to do multiple acidic sauces/dishes in a row?
Sounds like an enameled pan like Le Creuset might be the best for those. I haven’t had any issues with tomato sauce on cast iron though, probably takes some really long cooking to damage it.
Also, cast iron pans leach iron into food, and are therefore an effective way to treat anemia. Any one who needs a small, steady dose of iron can benefit from cast iron pans.
One time when I was a kid, I put a container of tomato sauce in the fridge, and covered it with aluminum foil. A few days later the foil had holes where it contacted the sauce. I still remember the nasty smell decades later.
Iron toxicity isn't really a thing, uptake is active and tightly controlled in the colon. Copper toxicity on the other hand, when you cook acidic foods for too long in a copper pan, that's a distinct possibility.
There's a lesson in that: journals print what people like to read. Everyone with a mild sense of chemistry already knows that you can't prepare tomato sauce or mulled wine in copper vessels, consequently such a paper will be rejected for being plain obvious. Stainless steel on the other hand, that's pleasantly controversial and you can debate about chromium and its oxidation state and essential nature and toxic concentration until the cows come home.
Haemochromatosis is very much a thing, depending upon your genetics, as there are hereditary traits that will cause some folks to take up iron too readily. As your body doesn't have any means besides blood loss of getting rid of iron, it can ruin your liver and other organs.
> Copper toxicity on the other hand, when you cook acidic foods for too long in a copper pan, that's a distinct possibility.
I visited a castle once (modern ish) that used to be owned by rich folk who hosted lavish parties, they had a fully equipped French style kitchen, including all copper pans. The tour guide said the cleanup was terrible, especially for things like tomatoes or eggs.
I think (unglazed) ceramic is your best bet. I use ceramic pans and glass pots. The corning glass pots last forever (probably my lifetime) but I have to replace my ceramic pans maybe every year or two. Seems worth the $50 for a peace of mind.
There is true (as per ISO standard) borosilicate glass available in Europe under various other marks (Simax, Boral,...). We use it widely but as it's softer than regular glass it's prone to scratches and subsequent catastrophical failure. Unlike lab reagents, food can contain sand grains and scratch the glass. Maybe that's the reason why Pyrex isn't borosilicate anymore.
This is the thing that perplexed me to a long time.
It turns out that pyrex isn't borosilicate in the states, but it is here in europe. I have a pyrex measuring jug that I've heat shocked loads of times and its still with me after ~18 years. However in the states I tried to use a pyrex just as I would at home, and the thing shattered.
I chuckle imagining this comment thread found in 50+ years, when a better understanding would lead to many common foods, cooking methods and materials being outlawed for being extremely unhealthy, and someone doing a double take, saying "What??? They KNEW?".
There's some teflon-like substance marketed as ceramic. I doubt it lasts more than a year, despite all the marketing claims saying it is indestructible.
I accidentally bought one on Amazon once, thinking it was a ceramic coated cast iron pan. Back it went.
I guess it's not false advertising if hundreds of fly by night companies all co-opt the name of the same superior technology.
It's definitely a thing in some cultures (Italian I know for sure, possibly Mexican too?). I personally boiled down some lasagna meat for 4.5 hours just the other day.
Oh tomatoes? Well, tomatoes love to be grown in acidic soil, which increases the uptake of nickel and chromium. And they had better be organic, because common contaminants of fertilizer salts include arsenic and cadmium. But you don't want to eat organics if they're grown from waste biproducts of animal farming, such as commonly used bone meal, because those concentrate heavy metals.
A long simmer really brings out the flavor, my grandmother would simmer it for hours, at least half a day if not longer. And she used fresh tomatoes out of her garden.
Yeah, at the end of last summer, I had a whole pile of excess tomatoes from the garden that I wouldn't be able to eat before they went off, so I bunged them in a very large saucepan and simmered them until they took up 1/3 the volume, and put them in hot jars. It's a fairly common way to preserve them.
The word gravy is sometimes used to refer to other sauces. In (American?) Italian cuisine it specifically refers to a very slowly cooked tomato sauce that is traditionally made on Sunday. In Indian cuisine it refers to the sauce made from spices and vegetables. In Southern US cuisine it's more like a béchamel. The etymology of the word is unclear but there is a suspected link to old French words for spice and stew.
Does anyone know why most stainless steel pots and pans contain large amounts of nickel? As I understand it, nickel is there to stabilize austenite, which has some potentially nice mechanical properties but is non-magnetic and not great at conducting heat. Nickel is also fairly expensive, so it seems to me that less than expensive alloys without nickel could be preferable.
So why doesn’t everyone use, say, 430 stainless steel pans?
The 400 series of steels (without nickel) are not ductile enough for certain kinds of manufacturing technologies.
So cutlery is made with the cheaper 400 series, but pots and other vessels are made from the more expensive 300 series, with nickel, because they need to survive a large deformation from a plane sheet of metal to a deep pot, without cracking during the deformation.
The fact that the nickel also ensures good corrosion resistance against hot acidic food juices is a bonus. The same corrosion resistance could be achieved without nickel, at higher chromium content (superferritic steels), but those steels are too fragile to be formed into vessels from sheets.
Reminds me of one of my personal heros, Bruce Ames[1] who invented the Ames test, a relatively cheap biological assay that tests for mutagenicity[2].
Essentially it turns out that tons and tons of stuff, both synthetic and natural is mutagenic to some degree, but we tend to think about it as a binary instead of a spectrum. His argument was that some things that are technically mutagenic, like pesticides and fire retardants have a net benefit in spite of this(e.g. pesticides make a better diet more financially attainable which has a bigger impact on public health than a very small increase in the base rate of cancer), but we lump them all together. It's why California's Prop 65 is just completely stupid; we lump fairly benign things like coffee and wine in with things like asbestos.
The quote I always think of is, "if you have thousands of hypothetical risks that you are supposed to pay attention to, that completely drives out the major risks you should be aware of."
Fire retardants are a net negative for public safety. Consumer protection groups, furniture manufacturers, and fire fighters all banded together to eliminate California's requirements for them. It still took over a decade. During that time, the fire retardant manufacturers were literally the only group that supported using them.
It rusts if you leave it damp, and the rust is porous and consequently impossible to keep clean; you have to scrub it off or remove it with acid. Restaurant kitchens wash and scrub their pots constantly but they also use a lot of stainless steel.
That's true, you have to keep it well seasoned to prevent it from rusting. Can you do that with carbon steel? I'd think the surface chemistry would be about the same, so maybe? Does the greater flexibility of the thinner cookware make the seasoning flake off?
Yes carbon steel cookware is seasoned almost exactly the same as cast iron. Although it's sometimes thinner, it's still quite dense and heavy cookware that's comparable to cast iron stuff in use and seasoning lifetime in my experience. It cooks just as fantastically well too--I love carbon steel pans.
Carbon steel is the same as cast iron, just less brittle due to lower carbon content. They sometimes make it thinner (doesn't have to be as thick since it's not cast), but there is plenty of thick carbon steel cookware out there too.
The carbon-steel itself is very tough, but most people try to keep a layer of seasoning on it to prevent rust. Sometimes it takes a lot of care to maintain that seasoning, and it still might flake off because of e.g. metal spatulas.
Good stainless steel, OTOH, is generally hard enough to survive reasonable run-ins with metal utensils, and doesn't require re-seasoning.
Carbon steel also contains chromium and nickel, and presumably also leeches those into food as you cook like stainless steel.
Cast iron is 100% iron.
FWIW, I use all three types of pans happily in my kitchen and won't judge anyone for using any of the three, but this question is kind of hilarious given the linked study about steel cookware.
plenty of cast irons have all sorts of things mixed in them. i don't think anyone particularly cares to use pure iron, because additives make the process easier.
if your pan manufacturer will even tell you which kind they used, you can check matweb for the composition.
some of them include chromium, nickel, molybdenum, etc.
I don't think they're really comparable though. For example: Stainless steel contains 10.5%+ chromium. Carbon steel contains up to 10.5%. Steel (with a non-trace amount of chromium in it) ends up leeching trace amounts of chromium into food. Some cast iron probably has trace amounts of chromium in it, but far less than the 10%+ in steel.
This may also leech chromium into food, but most likely at an even further insignificant amount. It's not part of the study and I am not a chemist, so I don't want to make a conjecture.
Chemistry is complex enough that layman cannot make any assumptions. For all we know stainless steel and carbon steel have higher content than the cast iron, but leach less because it's far more stable.
It’s the chromium. Cookware usually has nickel too. When a pan is advertised as 18-8, they mean roughly 18%Cr-8%Ni. Basically the same as 304 stainless steel. You have molybdenum additions in something like 316 stainless steel.
lol You're on a website catering to people who dislike having others prove them wrong and will stretch "technically correct" as far as possible, in the face of all else. If computers didn't exist, they'd be lawyers. If lawyers didn't exist, they'd be clergy.
I prefer spun iron which is as thin (and light) as a carbon steel pan but still pure iron. I do like cast iron, though, as it's just a thick chunk of metal you can throw in the oven or on a barbecue etc. without too much care.
Only for anemic women. Iron is mainly poisonous otherwise, especially for men or people with a history of hemochromatosis (ie British people). That's why multivitamins have separate ones "for women", everyone else just increases their risk of colon cancer.
This is ageism which assumes that the elderly are in constant misery and would rather be, or be better off, dead.
You’re wrong. When you are older you will realize that life is worth living at every age, and you will hope the young don’t treat you too badly in their ignorance.
This isn't really "new news", it's been a known thing for a while [0]
Personally became aware of it when looking for camping cookware; Stainless steel or aluminum are very good materials for pots taken on trip, they sturdy but not too heavy, tho have this issue of not being good for anything acidic due to the increased leeching.
For anyone wanting more details on stainless steel and teflon there's a short video on this from nutrition facts (so references the relevant research):
Referencing what others have said, it also mentions the Dupont cover up over Teflon, so personally I'm always sceptical of whatever the current advice is, because how long will it be before something surfaces to contadict it etc.???
I mean, they're totally for a different purpose though. Clad stainless cookware is meant for faster reaction to changes in temperature. Cast iron is great for searing but has way too much thermal mass to finely control temperature. Hard to beat copper and stainless steel for that.
From what I've read, cooking acidic food in cast iron can lead to iron poisoning. Though it is not clear how much dosage would be needed for that to happen..
Supposedly anodized aluminum is nonreactive. Besides enamel-coated pans and really well-seasoned cast iron, these seem like the only pans that don't leach anything? I guess we need tests to be sure. (you can also use stoneware for cooking, but not on a range)
Carbon steel might not be as bad as stainless--it doesn't have the nickel and chrome I assume like stainless.
I'd worry with anodized aluminum that the anodization can flake off with sharp utensils. I baby my aluminum cookware and it still gets some scratches.
There's some borosilicate glass cookware too, but IIRC it went out of fashion and can be hard to find in typical cookware forms like wide pans. It had some problems with thermal shocks and shattering I believe too.
I managed to find some more details on that story and it seems like they got the cause and effect reversed
>When World Kitchen took over the Pyrex brand, it started making more products out of prestressed soda-lime glass instead of borosilicate. With pre-stressed, or tempered, glass, the surface is under compression from forces inside the glass. It is stronger than borosilicate glass, but when it’s heated, it still expands as much as ordinary glass does. It doesn’t shatter immediately, because the expansion first acts only to release some of the built-in stress. But only up to a point.
>One unfortunate use of Pyrex is cooking crack cocaine, which involves a container of water undergoing a rapid temperature change when the drug is converted from powder form. That process creates more stress than soda-lime glass can withstand, so an entire underground industry was forced to switch from measuring cups purchased at Walmart to test tubes and beakers stolen from labs.
So it was very popular with drug labs, the recipe changed because new owners, so yes many drug lab chemists probably got hurt and they had to switch over from common Pyrex cookware to actual lab grade stuff. Makes a lot more sense, because I don't think even the DEA would try to restrict glassware. Maybe one day though!
Carbon steel is the same as cast iron, just with a lower carbon content. Both are only going to leach carbon and iron directly. Arguably though, the seasoning itself is probably some kind of polymerized hydrocarbon, and so you might leach polymer into your food when cooking on a well-seasoned cookware.
It is interesting that this regularly pops up on HN. People crave some kind of "aha!" subtle, gotcha explanation for why our health is falling apart, because they desperately need to ignore the quite obvious explanations of air and water pollution.
Well, since I posted this I can answer how I ended up there and the reason is rather simple.
We mostly use cast iron for cooking, except for cooking anything that is acidic (tomato, lime etc.) for which we use stainless steel.
So, got curious if stainless steel reacts with tomato or lime or not, since after all it's a metal, an alloy but metal.
So while I was bored of doing what I was doing, searched and found this, which was new info for me. So, decided to post it..
Some research indicates that obesity might be caused by water pollution, and the link between air pollution and lack of exercise should be clear enough.
+1 to this and your other diet related comments. think the issue in large part is insulin resistance driven by high carb processed food and replacing fat in things with sugar thanks to the (22 - 15) countries study. fasting & keto can help someone recover... but so much polarization that people don't want to hear that either. so... think _enough_ of the science is out there at this point, but things are going to keep getting worse, more obesity, type 2 diabetes, sicker. you'd think the mortality correlation with covid would have woken more people up. oh well.
Stainless steel is better than most alternatives. Slightly off topic, but I like lower temperature cooking. Instead of frying I like to simmer food in different vegetable broths with appropriate spices.
We're continuously ingesting plastics and various carcinogens from our food, air and water. I think the contribution from our stainless steel cookware is probably negligible by comparison.
It works great. The reason not to use it is that it will scratch the heck out of certain (resistive or induction) cook tops. Our cooktop has little raised matte nubbies that stick out a bit over the shiny ceramic surface. The nubbies are "pre scratched", and protect the rest of the cooktop. We have no problems with cast iron on it.
Some people use silicon mats to avoid scratches. The protective mat often burns or discolor the cooktop.
If you want to immediately ruin a ceramic cooktop, put a piece of aluminum between a hot pan and the ceramic top. Some sort of ion exchange happens, and the foil embeds itself below the surface, then flakes off. (Also, it smokes a lot,)
Yes is it a feature not a bug? "Nickel is a mineral. It is found in several foods including nuts, dried beans and peas, soybeans, grains, and chocolate. The body needs nickel, but in very small amounts. Nickel is a common trace element in multiple vitamins." [1]
Well, that is counter to what the above paper says:
Though Ni is known to be essential to the health of some species, it has not been proven to be essential to the health of humans (3). There are no known human enzymes or cofactors dependent on Ni for normal function
It is a feature, nickel is a cofactor in certain enzymes, and in industrial nations the main source for humans is their stainless steel cookware. On chromium being an essential trace element the jury is still out.
You're being misleading here. Your original comment heavily implied that nickel is essential for humans and stainless steel pans were an important source.
Per your source, nickel-containing enzymes are present in "primitive eukaryotes". Not humans. There are no known human enzymes or cofactors that depend on nickel.
Chromium, meanwhile, has been known to be an essential trace element in humans for many decades[0][1].
From the paper: Low levels of Cr (III) are essential for human health and metabolism of glucose, protein, and fat; however adverse effects of oral Cr exposures, such as dermatitis, are also known
>It has been demonstrated that Pb in glazed cookware and storage containers can leach with test acidic solutions and increased with duration of contact
So what matters is the hierarchy of the materials from this point of view, i.e. which are better and which are worse.
The best material for food-contact is glass, but glass, while perfect for storage, is not suitable for most types of cooking (even if it is quite possible for someone to eat only food cooked in a microwave oven, in glass cookware).
The next best material is titanium (commercially pure titanium, not the frequently encountered Ti-Al-V alloy). Titanium cookware exists, but it is normally too expensive, unless it is used in some activities where its low weight can justify the high price.
After these 2 cookware materials, which unfortunately are not an acceptable choice for most people, comes the stainless steel.
Yes, stainless steel will leach a little nickel and chromium. However this leaching will be large only for new cookware and it diminishes a lot for used cookware. Even in the case of people with nickel sensitivity, most of which are women, the quantities of nickel leached from used stainless steel cookware are far too low to have any effect.
All the other materials that are used for cookware, including ceramics, can be sources of much more dangerous leaching than stainless steel (excluding glass & titanium).
Ceramics and plastics are the worst (this includes any non-sticking coatings), because, unlike for metals and glasses, their chemical composition is usually kept secret by their manufactures, so you never know what they may leach.