Hydrogen peroxide is a slightly viscous liquid chemical compound that can be used as a disinfectant, whitening agent, and oxidizer. It is usually available as an aqueous solution. In high concentrations, hydrogen peroxide is used as a rocket propellant. Because hydrogen peroxide slowly decomposes when exposed to light, this very light blue solution is usually stored in an opaque, dark bottle. Hydrogen peroxide can be found naturally occurring in many different biological systems and was first synthesized in 1799 and first commercialized in 1908.
Lower concentrations are commercially available and legal to purchase over the counter, usually in 3% and 6% concentrations. When used in laboratories, the most common concentration is a 30% solution. Concentrations of higher than 68% are considerably more hazardous than lower concentrations and must be accompanied by safety data sheets and handled and stored with specific regulations, though these higher concentrations are available in commercial grades.
The majority of the hydrogen peroxide produced worldwide is used to bleach paper and paper pulp. Hydrogen peroxide is also widely used in combination with other ingredients as a bleaching agent in laundry detergent and laundry enhancers like OxiClean. When combined into organic compounds, it can be used to produce organic peroxides that can be used to bleach flour, to treat acne, or as explosives, among multiple other uses.
Hydrogen peroxide can also be used to treat wastewater and to sterilize surgical surfaces and surgical tools, and it is used as an environmentally safe antimicrobial agent. It has also been found to be effective in removing blood stains, can be used to bleach hair, and is part of the compound that produces the glow in glow sticks. These are just a few of the vast variety of uses for lower concentrations of hydrogen peroxide. Higher concentrations, such as those that are used as rocket propellant, are considered hazardous. In concentrations between 70-98%, hydrogen peroxide decomposes into steam and oxygen, allowing it to function as a monopropellant, though it may also be used to oxidize other propellants.
In low concentrations, hydrogen peroxide has been used to disinfect wounds for many years. While it does have antiseptic benefits and is inexpensive and widely available, it has been found to inhibit the formation of new skin cells and can lead to the formation of scars, and it is therefore not recommended for external application. It can also cause bleaching of the skin. It has also been used, historically, to treat gingivitis and reduce the bacterial biofilm of plaque in clinical settings. Because hydrogen peroxide is highly corrosive, and because it releases gas upon decomposition, swallowing hydrogen peroxide, even in low concentrations, is dangerous; therefore, its uses in dental settings are exclusively reserved for clinical administrations. When directly applied to the teeth in clinical settings it can help heal aggressive types of gingivitis by destroying bacteria and oxygenating the periodontium, making it harder for bacteria to survive. Because of its bleaching properties, hydrogen peroxide has also been determined to be a highly effective dental treatment used to to bleach and whiten the teeth.