Stainless steels are iron-based alloys. High resistance to corrosion is the principal characteristic of stainless steels, which is provided by chromium - the main alloying element. Enhanced corrosion resistance may be imparted by additional alloying constituents, primarily nickel and molybdenum.
Stainless steels have a wide range of applications, including those where human health may be involved. In these applications, stainless steels may come into direct contact with the human body. Cases include jewellery, cutlery, medical devices, automotive applications, food preparation and pharmaceutical settings. Stainless steels can be used without it exerting any negative influence on food, drinking water, beverages, or medical preparations it is in contact with.
Their health and hygiene characteristics - for instance, being easier to disinfect or clean - mean stainless steels contribute to human health and to society - ensuring that it is possible to safely prepare and store food and beverages, conduct medical interventions or to purify and channel water.
Additionally, stainless has excellent environmental characteristics. It does not seep into water and is safe in contact with organisms. Their high resistance to corrosion ad their restricted release into the surrounding environment when in the passive state constitutes safe containment of the alloying elements in stainless steel. In other words, while pure nickel, cobalt or chromium may in isolation have environmental or biological reactivity, alloyed in stainless steel they are not 'bio-available'.