How to clean your new stainless steel pots BEFORE you use them for the first time

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Tamara Rubin is a multiple-federal-award-winning independent advocate for childhood Lead poisoning prevention and consumer goods safety, and a documentary filmmaker. She is also a mother of Lead-poisoned children (two of her four sons were acutely Lead-poisoned in 2005).

• Tamara owns and runs Lead Safe Mama, LLC — a unique community collaborative woman-owned small business for childhood Lead poisoning prevention and consumer goods safety.
• Since 2009, Tamara has been conducting XRF testing (a scientific testing method) using the exact instrumentation employed by the U.S. Consumer Product Safety Commission to test consumer goods for toxicants (specifically heavy metals — including Lead, Cadmium, Mercury, Antimony, and Arsenic).
• Since July of 2022, the work of Lead Safe Mama, LLC has been responsible for 5 product recalls (FDA and CPSC).
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Published: April 19, 2024

You may have seen the “Prop 65” warnings on stainless steel pots or pans when you purchased them. You may have missed it — or as some do, perhaps you dismissed that warning as being “some form of ridiculous legal nonsense.” You can read more about the warning and what it means at this link. 

The reason many stainless steel pots and pans (even high-quality, expensive stainless steel pots and pans) come with a “Prop 65” warning (if manufactured by a company selling products in the State of California/ ships products to the State of California, and thus subject to the California State law known as Proposition 65, requiring disclosure of potential toxicant hazards in consumer products) is because Stainless Steel typically contains at least some amount of Nickel and Chromium (in addition to Iron, Cobalt, and traces of other metals).

A typical XRF reading for something made of “304” stainless steel looks like this (this reading set is from testing done on a stainless beverage flask — here’s a link with details):

• • • Chromium (Cr): 181,900 +/- 700 ppm
    • Vanadium (V): 1,555 +/- 164 ppm
    • Manganese (Mn): 8,169 +/- 482 ppm
    • Iron (Fe); 722,900 +/- 1,100 ppm
    • Cobalt (Co): 1,363 +/- 573 ppm
    • Nickel (Ni): 80,700 +/- 700 ppm
    • Copper (Cu): 3,033 +/- 174 ppm
    • Zinc (Zn): 61 +/- 35 ppm

The Prop 65 warning associated with stainless steel cookware is generally related to the concern for Nickel and Chromium in pots and pans. Even cookware made from low-nickel stainless steel alloys (that — in some form of doublespeak right out of George Orwell’s 1984 — are legally designated as “Nickel-Free!”) can test positive for up to 2,500 ppm Nickel, yet can still legally be labeled “Nickel-Free” (just as brass containing up to 2,500 ppm Lead — yep — can legally be sold as “Lead-Free Brass”)!

Specifically, the concern for Nickel and Chromium (and other potentially harmful metals) in “food-grade” and “high-quality” stainless steel is that cooking food in those vessels when using long-form cooking — particulaly if cooking acidic foods like tomato sauce — may cause some amount of those metals to leach into the food cooking in the pot.

To be clear: Leaching of metals from stainless steel into your food is not a concern across the board (to all types of stainless steel food-related/ cookware products); muffin tins, forks, knives, cookie sheets, etc. are not a leaching concern for these metals as those items are not used for long-form cooking with hot and acidic foods.

This concern only applies to stainless steel vessels that may be used for long-form cooking of hot and/or acidic foods (or stainless steel vessels that may be used to store acidic beverages like juices or coffee).

For the purposes of this article, we are defining “long-form cooking” as any food preparation involving more than, say, quickly-steaming some vegetables, or quickly frying an egg. (In other words, most “short-form” cooking is done in 10 to 30 minutes).

Long-form cooking is generally something that one is more likely to do with stews, chilis, soups, or sauces — tomato sauce, apple sauce, jams and jellies, etc. — that need to be reduced over time. As a general rule, if you need to cook something at any temperature (including on a low simmer) for more than a half hour (other than just boiling water), then it is verging on being “long-form” cooking, although this is a term most applicable to sauces and other dishes that need to be simmered (or reduced) for multiple hours, or even across multiple days.

Scientific research has demonstrated that long-form cooking (especially of acidic foods) can, under the right conditions, cause unsafe levels of metals to leach from stainless cookware into your food (note: The studies that most definitively demonstrated the concern for leaching specifically used tomato sauce cooked for eight to 10 hours — and even up to 20 hours — which is much longer than most people might typically cook tomato sauce).

1. Here’s a link to a related scientific study from September 19, 2013
   • Notable in this study:
     • Leaching is less significant in higher quality pots and pans.
     • The leaching decreases/ stabilizes over time (after the sixth use/ cycle with “seasoning”). If you wanted to rely solely on the information presented in this study, you could (in theory) buy some new stainless pans, put tomato sauce in the pan, cook for 20 hours (wash, rinse, and repeat six times) — and then any leaching for long-form cooking in these pans should be (at least) stabilized/ minimized. (More on this method below.)
     • Said another way: If you have been using your stainless pots for years (or decades), it is unlikely there is an ongoing concern (with the exception being for those who have Nickel allergies/ sensitivities or have a recommendation from a doctor to avoid any exposure to Nickel or Chromium).
2. Here’s a link that also references the above study from November 2012
3. Here’s a study from 1992
4. And here’s a study from 2015

What we learned from these (and other) studies is that the amount of metals leaching into the food diminishes significantly over time (with seasoning of the pans) to eventually become relatively non-concerning — especially when pots and pans are used for more typical short-form cooking activities instead of long-form cooking (i.e. after multiple rounds of cooking highly acidic tomato sauce in your pots for many hours at a time, the level of metals that could potentially leach into your food will lessen to the point of being below a level of concern by most standards and under most use scenarios).

Based on this information, the following two scenarios are likely true:

1. If you have well-seasoned vintage stainless steel pots (the “official” definition of vintage being “more than 20 years old”), they are likely already non-leaching — by virtue of having been heavily used over two or more decades.
2. If you are buying new stainless steel pots and pans:
   • Buy the best quality stainless steel pots and pans you can afford
   • Buy Nickel-free pots and pans if those are an option that is available to you
   • You can effectively “season” your new pots and pans (or “detox” them, if you like) by using the method demonstrated in the above-linked scientific studies shown to diminish the potential for leaching.
   • Here’s how…

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Here’s how to clean your stainless steel cooking pots before using them so they are less likely to leach unsafe metals into the food you cook with them in the future:

1. IMPORTANT POINT: The following is only relevant for UNCOATED stainless steel pots and pans
2. Wash your new pots and pans with soap and water (and an appropriate scrubber), as you normally would.
   • Note: New stainless pots and pans often ship with some manufacturing/ shipping film or residue, so you want to start by removing this (it could be oily, or sometimes a thin layer of gray or black dust — and should come off with normal washing).
3. Buy some inexpensive tomato sauce (generic-store-brand jars, cans, whatever is cheapest; you’re not going to consume it)… Buy several jars’ worth — enough to fill up your new pan or pot.
4. Pour the sauce in the pot and fill it up to nearly the top.
5. Put the pot on simmer around a low-to-medium temperature.
6. Keep an eye on it and let it simmer for up to 20 hours (adding water to reconstitute as it reduces) — if it starts to bubble, lower the temperature a bit (keep it as high as you can without it boiling over).
7. After 20 hours, discard the sauce (flush the sauce down the toilet, dump it down your sink disposal, anything other than feeding it to anyone)!
8. Wash the pot with soap and water and a scrubber, again, as you normally would
9. Go back to step 2 and repeat at least twice more — or up to six times total (the more times you do this, the less likely your pots and pans will be to leach unsafe levels of Nickel and Chromium over time, with longer-form cooking). Note: Completing this cycle more than six times is probably excessive,given the outcome of the first scientific study linked above.

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Update with a few key points

1. We did not publish this article with the expectation that you would spend hundreds of dollars on tomato sauce in an effort to “detox” every single one of your stainless pots and pans. We published this so you would be aware of the scientific studies and so you might consider “seasoning” the one or two pots that you do use for long-form cooking via this method.
2. As with any “seasoning” of cookware, if you use abrasive scrubbing solutions or abrasive scrubbing tools, any seasoning on the surface can be damaged (essentially exposing the metal underneath the seasoned surface) — in which case you may have to season your pots again.
3. This seasoning is NOT required for stainless steel pots and pans that you might use for short-form cooking (frying pans? small sauce pans? etc.) The concern for leaching has really only been proven with long-form cooking (or storage) of acidic food in stainless steel.
4. We here at Lead Safe Mama, LLC have always recommended “mixing it up” in your kitchen. Use a variety of glass, cast iron, and stainless steel. Never rely too heavily on one type of pot or pan. In this way, any potential risks are minimized. You can read more about that here, at this link. See some of the pots and pans we recommend here.

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In Conclusion

In general, we discourage long-form cooking of any kind; it’s not the safest type of cooking from multiple perspectives (not just the concern related to the potential for food to become contaminated with leached trace metallic toxicants). However, if you are going to cook long-form in any way (especially if it is “your grandmother’s secret spaghetti sauce recipe” or something similar) this seasoning process is at least one thing you can do (for the particular pot that you might use for that process) to make it safer when cooking long-form (or alternately, try cooking in modern glass cookware, which is often free of toxicants)!

If you have concerns about whether or not your cooking methods/ cookware might have exposed you to unsafe levels of Nickel or Chromium, it might be worth getting a heavy metals test (urine, hair, or blood — ask your doctor which they might recommend for you) to get a sense of whether or not you might need to make changes in how you cook. You can read more about that here.

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