Dimethylol dimethyl hydantoin (DMDM hydantoin), is a common preservative ingredient found in cosmetics production, construction materials, and household products.
It is used in the cosmetics industry and found in products like shampoos, hair conditioners, hair gels, Rite Aid Liquid Lubricant, and skin care products.
DMDM Hydantoin is a controversial ingredient because of its formaldehyde properties. Although the releasing of formaldehyde is the process that makes the environment less favorable for microorganisms (source), this process is what makes it an effective cleanser and preservative in many beauty products. According to RealSelf.com, it is primarily found in shampoo, conditioner, make up bases and foundations.
Some individuals develop allergic skin reactions when exposed to this preservative. These irritations typically appear as eczema or contact dermatitis. The chemical substance is generally easily removed from the skin by washing with soap and water. Health care providers suggest that once irritation occurs, individuals abstain from using products containing this ingredient. DMDM hydantoin is known to possess irritant properties and chemical workers can develop eye, skin, and lung irritations when working with the substance in large quantities.
None are recorded.
Other names for the compound include 1,2-demithylol-5,5 dimethyl hydantoin and dimethyl-2,4-imidazolidinedione
Source: WiseGeek, http://www.wisegeek.com/what-are-the-uses-of-dmdm-hydantoin.htm