@sjw Even tho iron is hard to maintain and to lift it's the less toxic way too cook food, besides stainless steel which comes after that.
Cooper is ok as long as the tin inside isn't gone. Aluminum is toxic when heated due to micro/nano aluminum oxides that detaches and gets ingested they have a bad habit of creating brain damage. As for téflon it's even more toxic due to the thing being petrol based and has the same tendency of being absorbed by the body.