food

Stainless steel: Leaches small amounts of heavy metals (chrome and nickel, though apparently the chrome is the more worrying one). Probably fine given the amounts. Lasts a long time. Can warp if heated unevenly, the handle can break off etc, but rather durable compared to other stuff.

Chromeless "stainless" steel: Still contains nickel. IKEA sells this for example. It's not really stainless, mine rusted. Do not recommend.

Cast iron or carbon steel (like a wok): No heavy metals (well, there shouldn't be, apparently heavy metals have been found in one manufacturer's steel at least). A black patina (called "seasoning") of polymerized fat/iron forms on the surface. Some of this goes back into your food. I have never seen a suggestion that this is a health concern but I also have never heard of anybody actually looking at that either. Best used for frying, not so good for liquids, especially acidic ones, which break down the seasoning. Cast iron especially is notoriously long-lived, the steel ones are more delicate: the seasoning doesn't stick as well and so they rust more easily and they can warp.

PTFE (aka Teflon): Polymers made from fluorine, often called "forever chemicals" since they don't break down. Breaks off from the pan surface and goes into your food. Since the final PTFE on the pan is fairly long-chain, it probably passes through your intestine w/o entering the bloodstream or reacting to anything. More concerning about these is their environmental impact, since these are manufactured from short-chain precursors that can go into all the organs and cause issues, and the factories seem to have already poisoned like most of the water supply and now they're literally everywhere. Also those pans don't last long and need to be replaced every couple of years.

Ceramic non-stick: Probably the way they work (manufacturer's secret or something) is by leaching silicone particles into your food. Nobody seems especially worried about this but also they're new, so I'm not sure anybody has looked at what that does exactly. Parchment paper is also lined with silicone and I guess that's been going on for a while, so who knows. Also nobody knows what exactly is in the ceramic, but let's assume they're like looking to not put any heavy metals into that. The main problem with these is that they suck, they basically turn from non-stick to rather sticky immediately. Too hot? No longer non-stick. Wrong oil? No longer non-stick. Use a couple of times? No longer non-stick. Teflon at least lasts like 2-5 years. These thing's lifetime is measured in weeks or months. I guess it could be used for boiling liquid where you don't care about non-stick.

Enameled steel or enameled cast-iron: This is basically a type of glass surface on top of the metal. Old ones from your grandma may contain heavy metals, new ones shouldn't. Rather non-reactive, so it shouldn't get into your food too much anyway. Can chip and so eating a broken off piece of glass is a potential health concern I guess. Apart from chipping, may break when dropped. Can also rust wherever the metal is exposed.

Straight aluminum or anodized aluminum w/o Teflon: This is sometimes used for sheet pans, for really large stock pots and for lightweight camping gear. Very sticky, so unsuitable for frying pans. It's a light metal that is naturally in the soil and veggies. Unlike heavy metals, the body will flush it out. We know it is dangerous (nerve damage) at very high doses, but low level exposure seems to have no ill effects.