DMDM hydantoin is an antimicrobial formaldehyde releaser preservative with the trade name Glydant.

[2][3] DMDM hydantoin slowly releases formaldehyde and works as a preservative by making the environment less favorable to microorganisms.

Formaldehyde is considered "an important metabolic product in plants and animals (including humans), where it occurs in low but measurable concentrations.

"[5] However, long-term exposure to formaldehyde (particularly routine inhalation of its fumes) is thought to cause irritation of the eyes and mucous membranes,[6] headaches, shortness of breath, and aggravation of asthma symptoms.

[7][8] It was declared a "toxic product" by the 1999 Canadian Environmental Protection Act,[9] and the US National Toxicology Program officially classed formaldehyde as "known to be a human carcinogen in June 2011.