What it is
Steel with at least ~10.5% chromium, which grows an invisible, self-healing chromium-oxide skin that stops rust. “18/8” or “18/10” on the base means 18% chromium and 8–10% nickel — that’s grade 304, the everyday standard. 316 adds molybdenum for extra acid and salt resistance; 430 (sold as 18/0) is the nickel-free budget cousin.
Why it’s safer
It’s solid metal: no polymer to fragment, no coating to flake, nothing that cares about boiling water or a scourer. The passive oxide layer keeps metal release very low in normal use, and a steel kettle or pot will outlive the person who bought it. Half my kit is stainless for exactly these reasons — including the kettle that replaced the billions-of-particles plastic one.
The honest caveats
It does leach metal into acidic food — measurably. Oregon State researchers simmered tomato sauce in 304/316 stainless: over six hours, nickel rose up to 26-fold and chromium up to 7-fold versus controls, and a single serve from a new saucepan carried ~483 µg of nickel — around half the tolerable daily upper intake, and above the oral dose that provoked reactions in sensitised people in challenge studies (J. Agricultural and Food Chemistry, 2013) lab human trial (the challenge-dose part). The redeeming detail: leaching fell ~65% by the third cooking cycle and stabilised around the sixth. Pans calm down with use.
Who this actually matters for: people with diagnosed nickel allergy or on medical low-nickel diets — for them, long acidic simmers in new stainless are a real route, and 430/18-0 or enamelled cast iron exists. For everyone else, normal cooking stays within tolerable limits, and the chromium is nutritionally trivial.
Marketing decoder: “surgical stainless” on a drink bottle is not a regulated grade — look for 304/18-8 or 316 stamped or specified instead. Undissolved salt in cold water can pit the surface over time; cosmetic, not toxic.
What I do
Steel is my default wherever heat, impact or daily abuse is involved: kettle, espresso makers, lunch containers, cutlery for twelve, strainer balls for loose-leaf tea. New cookware gets a few sacrificial cooks (water, then something non-acidic) before any slow tomato ragù — and the ragù mostly lives in enamelled or ceramic-lined pots anyway.