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Characterization of the decomposition of compounds derived from imidazolidinyl urea in cosmetics and patch test
Takahiro Doi1, Akihiro Takeda, Akiko Asada
1Osaka Prefectural Institute of Public Health, Nakamichi, Higashinari-ku, Osaka, Japan. tdoi@iph.pref.osaka.jp
Background:
Imidazolidinyl urea releases formaldehyde through decomposition. However, there have been few reports on the chemistry of imidazolidinyl urea in cosmetics.
Objectives:
The aim of this study was to characterize imidazolidinyl urea-derived compounds in cosmetics and to determine which compounds are responsible for the cross-reactivity with diazolidinyl urea.
Methods:
We analysed imidazolidinyl urea dissolved in aqueous solutions, imidazolidinyl urea patch test materials and imidazolidinyl urea-preserved cosmetics by high-performance liquid chromatography/photodiode array detection and liquid chromatography/mass spectrometry. The results were compared with those obtained with a diazolidinyl urea aqueous solution.
Results:
In the analysed cosmetic samples and patch test materials, imidazolidinyl urea was primarily composed of allantoin, (4-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (HU), (3,4-bis-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (3,4-BHU), and (3-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea.
Conclusions:
Two of the imidazolidinyl urea-derived major decomposition compounds - HU and 3,4-BHU - are common in the diazolidinyl urea-decomposed compound present in cosmetics. These compounds are possible causative agents of the cross-reactivity between diazolidinyl urea and imidazolidinyl urea.
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