Stainless steel is the most frequently recommended alternative to non-stick cookware, but questions about nickel and chromium leaching keep surfacing. The answer turns out to depend on the grade of steel, what you cook in it, and the physical condition of the pan. Here is what the metallurgical and toxicological research actually shows.
What 18/10 and 18/8 actually mean
Stainless steel cookware is an iron alloy containing chromium and nickel. The grade notation refers to the percentages: 18/10 means 18% chromium and 10% nickel; 18/8 means 18% chromium and 8% nickel; 18/0 means 18% chromium and no nickel. Chromium gives stainless steel its corrosion resistance by forming a thin, self-repairing oxide layer on the surface. Nickel improves the alloy's ductility, polish, and resistance to acidic attack. For cookware, 18/10 is the most common premium grade. Pans marketed as “nickel-free stainless” use more chromium but can pit more readily when exposed to salt and acid over time.
What the leaching research shows
The most frequently cited study is Kamerud and colleagues, published in the Journal of Agricultural and Food Chemistry in 2013. The researchers simulated home cooking by preparing tomato sauce in stainless steel stockpots at a simmer for six hours, then storing the sauce overnight. New pots released chromium at roughly 88 micrograms per 126 grams of sauce and nickel at about 34 micrograms. After six subsequent cooking cycles, the leaching rate dropped by roughly half and continued to decline, suggesting that new pans leach more and stabilise with use.
Context matters: the European Food Safety Authority's tolerable daily intake for nickel is 13 micrograms per kilogram of body weight, which translates to about 910 micrograms per day for a 70 kg adult. Even the highest leaching from a brand-new stainless steel pot was well under this threshold for a single meal. For people without a nickel allergy and without nickel-sensitive inflammatory conditions, the exposure from stainless steel cookware is considered low-risk.
Acidic foods and damaged surfaces
Two conditions increase metal leaching significantly. The first is prolonged cooking of acidic foods: tomato sauce, citrus, vinegar reductions and wine sauces simmered for hours. The chromium oxide passive layer is stable at neutral pH but weakens in acid. The second is mechanical damage: deep scratches, pitting from salt added before water boils, or aggressive scrubbing with abrasive pads can compromise the surface.
Research on acidic food simulants has found that scratched stainless surfaces release two to three times more chromium than intact surfaces. For people with diagnosed nickel sensitivity (around 8 to 15% of women and 1 to 3% of men by patch testing), this is worth considering. For everyone else, the cumulative exposure over a year of normal cooking remains well below toxicological thresholds.
Stainless steel versus cast iron
Cast iron has its own trade-off: it leaches iron into food, particularly acidic foods, which is beneficial for most people but can be problematic for those with hereditary haemochromatosis or iron overload. A study in the Journal of the American Dietetic Association found that spaghetti sauce cooked in cast iron contained roughly nine times more iron than the same sauce cooked in glass. For adult men and post-menopausal women who do not lose blood regularly, chronic iron accumulation can contribute to oxidative stress. For pre-menopausal women, children, and anyone with iron-deficiency anaemia, it is net beneficial.
Neither material carries the risks associated with non-stick coatings, whose PTFE layer can degrade above 260 C and release PFAS compounds. Both stainless steel and cast iron are stable across the full range of home cooking temperatures and neither sheds synthetic particles into food. Between them, stainless steel is the better choice for long-simmered acidic dishes; cast iron is the better choice for searing and for those who benefit from extra dietary iron.
Practical recommendations
Choose 18/10 stainless steel with tri-ply or five-ply construction for everyday cookware: the aluminium or copper core improves heat distribution, and the austenitic surface resists pitting. All-Clad D3, Made In, and Demeyere are the most frequently tested and well-reviewed options. Use common sense with acidic foods: cook long tomato reductions in enamelled cast iron when possible, or transfer finished sauces to glass for storage rather than leaving them overnight in the pot. Avoid scoring the surface with metal utensils and skip chlorine-based cleaners that pit the passive layer. Replace any pan with deep gouges or visible pitting.
For context: if you are currently cooking on a scratched non-stick pan, replacing it with any stainless steel pan, regardless of grade, is a significant reduction in daily chemical exposure. The nickel and chromium question matters at the margins; the PFAS-in-non-stick question does not.