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Stainless steel leaches nickel and chromium into foods during cooking (2013)
- lkrubner 5y agoAlso, 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.
- pphysch 5y agoOTOH it can introduce dangerous amounts of iron if you cook highly acidic foods in it
- _jal 5y agoYour food will taste really gross well before it is dangerous. And cooking acidic foods in cast iron ruins the seasoning, so anyone who uses it regularly already doesn't do that.
- HarryHirsch 5y agoIron 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. That explains the nature of the investigation.
- nanomonkey 5y ago> Iron toxicity isn't really a thing. 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.
- Cthulhu_ 5y ago> 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.
- CoastalCoder 5y agoOne 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.
- uneoneuno 5y agoI have a feeling you made an aluminum / tin battery with the tomato sauce as the electrolyte?
- perilunar 5y agoSee also the story of the lucky iron fish: https://en.wikipedia.org/wiki/Lucky_iron_fish https://en.wikipedia.org/wiki/Lucky_iron_fish
- iab 5y agoAnybody close to just giving up at this point?
- DeWilde 5y agoIn the worst case, we're left with air-frying as a healthy way of cooking.
- deleted 5y ago[deleted]
- quantified 5y agoCast iron FTW. Haven’t checked if an enamel dutch oven is naughty or nice. Slow cooker’s pottery glaze is unknown.
- anonporridge 5y agoThis. We literally take iron as a supplement because it's an essential mineral for the body. K.I.S.S.
- deleted 5y ago[deleted]
- s5300 5y agoObligatory cereal-iron extraction https://youtu.be/NHqN-Be5nlU https://youtu.be/NHqN-Be5nlU
- Johnny555 5y agoI think only pre-menopausal women should routinely take iron supplements. Men run the risk of getting to much iron.
- astrange 5y agoOnly 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.
- tus666 5y agoAnd these things are bad for us? I mean it's not lead.
- dcchambers 5y ago> Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Literally the first sentence in the abstract when you click the link. The rest of the abstract summarizes the study nicely in a small paragraph.
- lazide 5y agoHow is that comparable to lead at all?
- dcchambers 5y agoI never said it was. I simply pointed out what the study itself says about the effects of chromium and nickel on the body.
- lazide 5y agoYou replied to a comment specifically comparing it to lead?
- deleted 5y ago[deleted]
- refurb 5y agoYou do realize “cutaneous adverse reactions such as dermatitis” is just a rash right?
- somethoughts 5y agoYes 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] [1] https://www.webmd.com/vitamins/ai/ingredientmono-1223/nickel https://www.webmd.com/vitamins/ai/ingredientmono-1223/nickel
- hollerith 5y agoI heard that cheap stainless pots leach fewer toxins than the expensive ones.
- cyounkins 5y agoWorth noting that this investigation specifically analyzes highly acidic tomato sauce and that is likely to be the worst case scenario. Still very valuable research!
- WinterMount223 5y agoTomato sauce is not only acidic but also has a strong chelating agent citric acid which is known to corrode stainless steel in industrial settings.
- friedturkey 5y agoPlenty of people eat tomatoes and pasta quite often so it’s also not an unreasonable test case.
- perihelions 5y agoAlso, 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.
- jeffbee 5y agoYeah, 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.
- cyounkins 5y agoStainless 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.
- bluedino 5y agoI'm using my grandmothers cast iron. She and my grandfather lived well into their 50's so I should be good.
- alfalfasprout 5y agoI 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.
- yumraj 5y agoFrom 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..
- Arrath 5y agoIt the other direction, if you're iron deficient it can be a good thing!
- melling 5y agoWell into their 50s is not very old. 100 years ago the average lifespan wasn’t as good but there was more childhood mortality, no antibiotics, etc.
- CincinnatiMan 5y agoPretend you're on Reddit and you'll realize it was a joke.
- melling 5y agoThere’s way too much noise on Reddit so I don’t read it often. HN tends to have higher signal without as much noise.
- 5y ago
- syntaxing 5y agoI 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.
- germinalphrase 5y agoWhat kind of ceramic pan are you describing here? My assumption was ceramic coated cast iron, but you would hardly replace that yearly.
- AussieWog93 5y agoI know people who've bought cheap enameled cast iron, and theirs died after around 2 years of heavy use.
- hedora 5y agoThere'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.
- syntaxing 5y agoI use green pans. While they still “work”, the nonstick properties diminish which isn’t the end of the world, but gets annoying for things like eggs.
- WinterMount223 5y agoUnglazed ceramics can leach arsenic depending on their composition, so if you are really paranoid your safest bet is new lab grade borosilicate glass.
- every 5y agoThat would be the original borosilicate Pyrex which is no longer made. Fortunately, I inherited a ton of it from my parents...
- hprotagonist 5y agoI don't know about you, but i do not regularly simmer tomato sauce for 2-20 hours at a time.
- Johnny555 5y agoA 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.
- AussieWog93 5y agoIt'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.
- assttoasstmgr 5y agoSounds like someone's never had Sunday gravy with braised short ribs before.
- hprotagonist 5y agoyou put tomatoes in your gravy? takes all kinds, i guess.
- edgyquant 5y agoI assume they were using tomatoes to make the braised short ribs
- ubercore 5y agoThey might have been using it in the Italian American sense (also called Sunday Sauce): https://cooking.nytimes.com/recipes/1022972-sunday-sauce https://cooking.nytimes.com/recipes/1022972-sunday-sauce
- globular-toast 5y agoThe 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.
- deleted 5y ago[deleted]
- jeffbee 5y agoIt 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.
- loudtieblahblah 5y agothe more obvious explanation are diets that arent healthy.
- donkeydoug 5y ago+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.
- yumraj 5y agoWell, 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.. As simple as that... :)
- refurb 5y agoI was with you until “air and water pollution” as I expected the much more obvious cause of “obesity and lack of exercise”.
- jeffbee 5y ago
- 0xbadcafebee 5y agoSupposedly 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)
- qbasic_forever 5y agoCarbon 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.
- hedora 5y agoIt was popular in drug labs, so they replaced the consumer stuff with something that violently explodes if used for chemistry. Of course, people that were using it to, you know, cook food, or in research labs ended up in some pretty dangerous situations too. Many underfunded grad students were maimed. (Really.)
- Gigachad 5y agoI find it hard to believe they did this to stop people making drugs rather than because it was cheaper and good enough for most.
- mardifoufs 5y agoI 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. https://www.popsci.com/science/article/2011-03/gray-matter-cant-take-heat/ https://www.popsci.com/science/article/2011-03/gray-matter-c... 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!
- carterschonwald 5y agoSo 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.
- yumraj 5y ago> all stainless steels need to be “passivated” in order to be properly stainless. Does the passivated layer survive scrubbing and dish washing?
- cyounkins 5y agoIt can be damaged physically or chemically but the oxide layer is self-healing upon contact with oxygen.
- jeffbee 5y agoThe depth of the chromium-rich top layer would be measured in nanometers at most, while a visible scratch would have to be tens of microns in size.
- Tade0 5y agoIsn't stainless steel a uniform alloy of chrome, nickel and iron?
- jeffbee 5y agoIt 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.
- senectus1 5y agocan you use cast iron on an induction cooktop? I mean, it should work... but is there any reason not to?
- hedora 5y agoIt 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,)
- perilunar 5y agoYes cast iron works. Most ferrous metals do but some stainless steels don't.
- agumonkey 5y agowho here cooks with steam ?
- faramir 5y agoWow... I use a stainless steel pan every day AND I'm covered in eczema. Maybe it's time to get a new pan.
- hedora 5y agoGet an allergy screening. They can test for nickel sensitivity.
- emmelaich 5y agoSome 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.” https://www.hmpgloballearningnetwork.com/site/thederm/site/cathlab/event/goblins-copper-time-nickel-directed-us-health-policy-here https://www.hmpgloballearningnetwork.com/site/thederm/site/c... Also, (my speculation) it is the origins of the name of Copernicus.
- adhesive_wombat 5y agoThe -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!
- emmelaich 5y agoYes, I found that after and decided not to spoil my fun. The area around Kopernik is rich in minerals including copper so I'm leading towards copperer. Either a copper miner or one who works with copper.
- ajuc 5y agoCopper 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).
- adrian_b 5y agoIt 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.
- hawski 5y agoWouldn't iron be the best at least for pans? Also what about enamel?
- adrian_b 5y agoAny 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.
- amluto 5y agoDoes 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?
- adrian_b 5y agoThe 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.
- Shadonototra 5y agoso back to steaming + glass, thanks
- Litost 5y agoFor anyone wanting more details on stainless steel and teflon there's a short video on this from nutrition facts (so references the relevant research): https://nutritionfacts.org/video/stainless-steel-or-cast-iron-which-cookware-is-best-is-teflon-safe/ https://nutritionfacts.org/video/stainless-steel-or-cast-iro... Part of a series of three which includes aluminium: http://nutritionfacts.org/video/are-aluminum-pots-bottles-and-foil-safe http://nutritionfacts.org/video/are-aluminum-pots-bottles-an... and Melamine dishes and Polymide utensils: http://nutritionfacts.org/video/are-melamine-dishes-and-polyamide-plastic-utensils-safe http://nutritionfacts.org/video/are-melamine-dishes-and-poly... 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.???
- mark_l_watson 5y agoStainless 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.
- iandanforth 5y agoSibling 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.
- perlgeek 5y ago> 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.
- vannevar 5y agoWe'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.
- deepsquirrelnet 5y agoPlants uptake nickel and chromium from soil in small amounts.