Other names for diazolidinyl urea are germall II, germaben II (mixture), II-E, tetramethylolhydantoin urea, and N,N1 - bis (hydroxymethyl) urea. It’s prepared from allantoin, formaldehyde, and sodium hydroxide.
Diazolidinyl urea is added to deodorants and personal care products to extend their shelf-life and suppress the activity of odor-producing bacteria. It works by releasing into the product you’re using, formaldehyde which the US Environmental Protection Agency and the International Agency for Research on Cancer consider cancer-causing (carcinogenic).
In certain jurisdictions like the European Union, manufacturers are required to indicate their product contains formaldehyde if the diazolidinyl urea content is in excess of 0.05%. The US Food and Drug Administration recommends the content of diazolidinyl urea be no more than 0.5% to ensure that the formaldehyde released into the finished product doesn’t exceed 0.2%. Some health authorities recommend avoiding personal care products with diazolidinyl urea altogether. However, if you insist on using them, just make sure you don’t use them as stay-on.
Exposure to diazolidinyl urea can cause contact dermatitis and allergic skin irritation and reactions, producing mild and aggravated symptoms such as burning sensation, redness, swelling, itching, fluid-retaining blistering, flaking, and scaling. It can also cause serious eye irritation as well as reproductive effects. Other signs and symptoms are irritation of the mucous membranes, joint and chest pain, chronic fatigue, ear infections, dizziness, headaches, immune-system dysfunction, endocrine disruption, and impairment of the nervous system (neurotoxicity).
Other formaldehyde-releasing preservatives and potential co-reacting chemicals you need to avoid are imidazolidinyl urea (germall), quaternium-15, broponol, glydant (DMDM hydantoin), sodium hydroxylmethylglycinate, and trimethylolnitromethan.