This reaction shows the oxidation of phenol by iron and peroxide. This combination of iron, which comes from iron oxide in the sediment, and the peroxide, commonly released by animals and plants into the environment, is known as the Fenton Reagent. This reagent is used to oxidize phenol groups by the use of a radical hydroxide group produced from the peroxide in the p-benzoquinone. This product of phenol's oxidation is now leached into the environment while other products include iron(II) and water. P-benzoquinone is listed as being a very toxic, acute environmental hazard.