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How many times you have heard that metals can leak into your food from cookware, food package, or cutlery?
But are these claims actually true? is metal leaking significant, or there are just tiny traces of it that finished up in the food?
There are different Stainless steel alloys used in the kitchen, and 304-grade stainless steel is one of the most common ones. I have been using cookware from Stainless steel since I started to cook more seriously in secondary school, and my concerns about its safety were raised as I deepened my education in science during my bachelor’s and master’s studies.
I wanted to make clear conclusions, is Food grade stainless steel like 304, safe for use or should I fully replace my Stainless steel cookware?
In general, 304 stainless steel is safe to use as a food contact material. The alloy contains 8-12% nickel which is commonly addressed as a concern for skin-related problems like eczema. However, studies have shown that neither nickel nor other metals from stainless steel leak in amounts significant for health.
In this post, I will summarize the opinions of the Food safety authorities and related institutions about the health concerns of using food grade Stainless steel alloys like 304.
The post will gather comprehensive scientific, and regulatory data so you will be able to go out of the post with a more clear mind about the safety concerns of stainless steel.
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Is 304 Stainless steel safe? What are the potential safety concerns of using Stainless steel?
*In the following text I will also use the abbreviation ,,SS” for the stainless steel
The 304-grade stainless steel is one of the most commonly used alloys for food and beverage applications in the modern world. It contains approximately 18–20% mass fraction chromium, and 8–10.5% nickel(1).
Moreover, there are two common types of 304-grade, often called 18-8 or 18-10 to reflect the percentages of chromium and nickel in 304 SS grade respectively(2.).
Nickel helps iron atoms in steel to organize in a specific order(crystalline structure) which increases the overall ductility and steel-forming abilities(3.). The addition of nickel in sufficient percentage, typically 8-10% imparts these unique properties of steel alloys that contain this metal(3.)
One of the common concerns about the use of stainless steel for food contact applications is the leaking of nickel. In some species Ni is known to be an essential element(4), however, in the human body non of the metabolic reactions require this methal for normal function(5).
The main health concerns related to nickel chronic exposure, are related to skin irritation problems like allergic contact dermatitis, flare-up eczema, or systemic dermatitis in individuals sensitive to nickel.
Toxicological studies indicate that a single oral dose of Ni as low as 67 μg can cause the recurrence of mentioned skin-related problems (6,7). Studies have shown the severity of dermatitis has a dose-dependent relationship to oral doses of nickel (8).
However, as European Food Safety Authority concluded nickel exposure doesn’t have a cancerogenic effect on humans:
“Based on i) the lack of epidemiological data suggesting that nickel compounds cause cancer after oral administration, ii) the lack of tumors in the carcinogenicity studies in experimental animals after oral administration of soluble nickel compounds and iii) the mode of action, the CONTAM Panel considered it unlikely that dietary exposure to nickel results in cancer in humans (EFSA CONTAM Panel, 2015)”(9.)
So after considering this information coming from the world’s most authoritative food safety authorities, my conclusion was that chronic exposure to nickel from stainless steel cookware(and other objects), in some specific cases, causes skin-related problems. Additionally, it is not related to serious health concerns such as cancer or developmental problems(9).
My last step in research about SS metal leaking concerns was to understand what are the maximal daily intakes, proposed by the international regulatory bodies and to see does metal leaking from SS cookware(Including the common 304 ss grade) significantly contributes to the passing of these limits.
The information summarized in the following subheading made this point fully clear about this point.
Does 304 Stainless steel leak metals in significant amounts?
In 2013, the Council of Europe (CoE) published the latest limitations for other metals that can be found in food-grade metal alloys such as Stainless steel 304 grade. These included specific release limits for iron, nickel, chromium, manganese, and molybdenum and included a new, more aggressive test for simulating the use of food-grade alloys in food preparation.
CoE set the maximal daily Nickel intake of 0.14mg per kg of food also known as the specific release limit (SRL). Here you can find the CoE guidelines abstract reference and on this link full text is available. Unfortunately, the full text is only accessible for free in Slovenian Language, but you can find the part about Nickel on page 77.
So the final puzzle in my research about the exposure of nickel and other metals from stainless steel was to find the official study that proves that the metal leaking levels from SS are not exceeding any of these strict regulations set in Europe.
This is exactly what the team of stainless commission of the internationally-renowned institute KTH(Royal Institute of Technology) in Sweden did.
They tested seven grades of stainless steel(Including 304) and demonstrated that all the grades tested are safe for food preparation, with the metals leaking amounts below the Specific Release Limits (SRL) set by the CoE guidelines.
Finally, the study demonstrated that methal release significantly drops down after repeated use of tested stainless steel after the initial exposure.
You can find the whole KTH study on the link here.
This was the final piece of information to complete the puzzles about my safety of using stainless steel cookware and removed many of the concerns that I had previously.
However, there are some cooking practices that I avoid with stainless steel, and in the further text you can find more about that.
Which practices to avoid with 304 SS to keep it safe?
Even the food authorities have agreed that the nickel exposure from stainless steel cookware is (much) lower than the allowed daily intake(mentioned KTH study as a reference), we are exposed to nickel from food and water sources.
Edible mushrooms, cocoa or cocoa-based products, beans, seeds, nuts, and grains have been indicated as the ingredients with the highest measured levels of nickel(10.).
It has been estimated that adults in the U.S. are estimated to ingest an average of 69 to 162 μg of Ni per day (7), which is up to 10% of the maximally allowed intake of 70kg per person.
As mentioned before some toxicological studies indicate that a single oral dose of Ni as low as 67 μg can cause the recurrence of mentioned skin-related problems (6,7).
Since I personally suffer from eczemas I tried to avoid some extreme uses of stainless steel cookware such as prolonged cooking of acidic-based sauces, as an extra safety measure. But I use the SS normally for all other purposes.
Finally, there is a stainless steel grade that doesn’t contain nickel as you will find in the chapter below.
So it can help you avoid any further thinking about nickel.
For people who don’t suffer from contact dermatitis, flare-up eczema, or systemic dermatitis I believe that these extra cautions seem nonsense and that using od SS can be performed without limiting mentioned cooking practices.
The same thing I a suggestion that I give to other people in my family.
What is the safest stainless steel grade? Is 304 safer than others?
There are several common-use food stainless steel grades like 304 and 316. In both cases, the nickel content is about the same around 8-10%. Additionally, the percentage of chromium and iron varies only up to several percent.
The only exception will be the stainless steel grade 430 which contains Less than 1% nickel and can be a great option for people who have concerns about nickel exposition. Some brands are even available on Amazon.
Even the nickel leaking is not a concern for most people as evaluated earlier, I would highlight the difference in the rusting properties of different SS grades used as food contact materials. Finally, resistance to rusting can be an additional safety factor when choosing the SS grades for you.
For that Take a look at one of my upcoming posts here, where I will gather the info about SS grades, their antirusting properties, performance, and more.
In the 21 century, bare metal cookware became standard in many homes and restaurants. Even if there are options available stainless steel safety has solid background compared to some other metals in use.
For instance, you will be able to find my article about stainless steel and aluminum cookware where I have compared the safety behind both cookware types and the existing set of scientific publications, government authority reports, and expert opinions.
Finally, many people today use non-stick cookware which safety is misinterpreted. Shortly, these utensils can be used safely, but in a very narrow range of cookware practices.
This is why from my point of view stainless steel gives much more versatility in cooking while being safe for use. However, to make your judgment about this you can take a look at two deep reviews that I have written about ceramic nonstick cookware safety as well as granite cookware (which is commonly made from Teflon as you will see)
Bottom line
My family uses SS since I was a child. Moreover, I have been using it since my very first steps in the kitchen. Solving the safety concerns about SS cookware was a big step for me after which I have continued to use it almost daily.
In the past years, I have been experimenting with different cookware pieces and brands while enjoying the cooking practices like meat searing, sautering veggies, and spicing up my favorite risotto recipes.
In recent times I fell in love with two companies of played stainless steel cookware that have produced well-designed, light, and affordable SS pans while offering a lifetime guarantee. See the picture below.
So If you are planning to start cooking with SS maybe you can start from check the websites of Misen and Sardel and taking a look at what they offer, and get your own impression.
In the future, I am looking forward to making articles about my experience with these brands, their comparison, and test-up videos to show what you can expect them and what not.
So stay along with Safetouseit and be ready for fresh content about the cookware safety summaries like this one, results of testing different cookware performances and good directions if you are diving deeper into cooking and finding the cookware types that it will fit you the best.
