A key biochemical intermediate, in the form of the peroxide and hydroperoxide anions, acting as an oxygen donor. It also reacts in biological systems to make the hydroxyl radical and superoxide anion.
It is used diluted in water as an antiseptic. 3% (10 volume) hydrogen peroxide is used for cleaning wounds, debriding dead tissue, rapidly stopping capillary bleeding and is widely available. It is rather dangerous if swallowed due to prompt gas decomposition. Higher concentrations are usually considered hazardous.Some 3% solutions are stabilised by acetanilide which is a toxin. Peroxidase enzymes are found in most life forms, peroxide scavengers are probably universal , as is the mitochondrial electron transfer chain and many have hydrogen peroxide-inducible gene activity. Superoxide dismutase, catalase and glutathione peroxidase are just some of the key enzymes in man associated with this chemical with haemoglobin and myoglobin also having roles.
One of the most powerful oxidizers known, surpassed only by fluorine, hydroxyl radical (which is catalytically produced from it) and ozone. While it will decompose exothermically into water and oxygen gas spontaneously, biological systems have large amounts of peroxidase enzymes and effective catalytic peroxidases like haemoglobin that ensures this reaction occurs at very low concentrations of hydrogen peroxide. It can also act as a reducing agent and produce oxygen gas in some reactions. Often used as a bleach. See Wikipedia:Hydrogen peroxide.