Osmium is a shiny, silver metal that resists corrosion. It is the densest of all the elements and is twice as dense as lead. Osmium has only a few uses. It is used to produce very hard alloys for fountain pen tips, instrument pivots, needles and electrical contacts. It is also used in the chemical industry as a catalyst. Osmium has no known biological role. The metal is not toxic, but its oxide is volatile and very toxic, causing lung, skin and eye damage. Osmium compounds are attracting increasing attention as potential anticancer drugs. Osmium complexes are considered interesting alternatives to ruthenium-based anticancer agents because of their relative inertness and sufficient stability under physiological conditions.