Diazolidinyl Urea
Explained
Diazolidinyl Urea is an antimicrobial preservative. It is commonly used to prevent bacterial, yeast, and mold growth.
Why is it controversial?
Diazolidinyl Urea slowly breaks down into formaldehyde, an effective microbe killer but also a known allergen/carcinogen.
Some people who are allergic to imidazolidinyl urea also react to diazolidinyl urea. It ranked as the 14th most common allergen in patch tests from 2005–06.
Safety reviews show that at concentrations under 0.5%, the formaldehyde released remains below the accepted safety limit, making it considered safe for cosmetic use.
Ultimately, its safety depends on individual skin sensitivity and personal comfort with formaldehyde-releasing preservatives.
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