Diazolidinyl Urea: Cosmetic Preservative

Diazolidinyl urea is an ingredient used in skincare and cosmetic products to help ensure the safety and longevity of the product. It is a preservative, preventing the growth of bacteria, protecting your products from spoilage. In addition, this substance is a water-soluable preservative that is considered to be safe at concentrations up to 0.5%. It usually comes in a fine white powder and is often combined with other parabens and preservatives in order to keep the product safe from use contamination and spoilage. Diazolidinyl urea is found in a large variety of products such as makeup, aftershave, haircare, skincare, nail care, and bath products.

Diazolidinyl urea in cosmetics and patch test materials

A wide variety of antimicrobial preservatives, such as formaldehyde and formaldehyde-releasers, are used in cosmetics. Diazolidinyl urea (DU) is one of the most commonly used preservatives in cosmetics, and is known to release formaldehyde through its decomposition. The released formaldehyde concentrations of DU -containing cosmetics and factors that affect formaldehyde release have been studied previously. However, few data are available on the decomposition properties of DU in cosmetics, and analytical methods for measuring DU were only developed recently. In a previous study, (4-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (HU) was reported to be the only end degradation product formed in basic conditions. Three molecules of formaldehyde are released from DU to give HU, and the pH conditions of actual cosmetics range from acidic to basic, so DU decomposition compounds other than HU are suspected to exist in cosmetics containing diazolidinyl urea. In this study, we show the DU decomposition properties in buffers, cosmetics, and patch test materials. Furthermore, suspected DU decomposition compounds were isolated by high-performance liquid chromatography (HPLC), and the isolates were characterized by liquid chromatography–electrospray ionization–mass spectrometry (LC-ESI-MS) and 1H-nuclear magnetic resonance (1H-NMR) analysis. Elucidation of DU decomposition in cosmetics and patch test vehicles is thought to be key to understanding contact dermatitis caused by diazolidinyl urea in cosmetics and the cross-reactivity between DU, other formaldehyde-releasers, and formaldehyde itself.[1]

The present study demonstrated that there were at least four diazolidinyl urea decomposition compounds – with molecular weights of 188, 218, and 248 – in samples prepared from buffers, cosmetics, and patch test materials. The compositions of these degradation compounds were different between the cosmetics and pet. patches. Our results also suggest that DU is mostly present as HU and 3,4-BHU in cosmetics. In our previous study, we could hardly find a peak with the same retention time as the diazolidinyl urea standard solution in an HPLC-PDA analysis of cosmetic samples. As formaldehyde was detected in the cosmetics, we regarded DU decomposition as the reason why the peaks disappeared. HPLC-PDA and LC-MS studies suggested that the detected decomposition compounds had taken one or more molecules of formaldehyde from DU. To clarify whether compound B was HU, we tried to completely degrade DU, as described previously. However, we did not observe the complete conversion of DU to compound B after 2 hr of stirring in 0.2 mol/l NH3 at a concentration of 30 mg/ml. In the chromatogram of this solution produced by HPLC-PDA, peak A covered 50%, and peaks B and C covered approximately 20% of the total peak area (data not shown). The diazolidinyl urea-derived decomposition products differed between the cosmetics and patch test preparations. To test the contact sensitivity of the DU present in cosmetics, patch tests with HU and 3,4-BHU in petrolatum should be performed.

Cross-reactivity and clinical relevance of diazolidinyl urea

Diazolidinyl urea (DIAZ)is a relatively new form- aldehyde (FORM)-releasing biocide that has been used extensively since 1982 as a preservative in cosmetics and hair-care products. Introduced under the trade-name of Germall II, it is the most active member of the imidazolidinyl urea group. At concentrations of 0.1%to 0.5%, Diazolidinyl Urea provides superior broad-spectrum inhibition of gram-negative and gram-positive bacteria, molds, and yeast; activity against fungi is limited. It is colorless, odorless, stable, water-soluble, and effective over a wide ph range. The question of whether DIAZ is capable of dermal sensitization has been debated.Berke Rosen classified DIAZ as a nonsensitizer 1982. However, Jordan subsequently found DIAZ to have a higher incidence of sensitization than imidazolidinyl urea (IMID) (2/150). In a test of sensitization in guinea pigs, Diazolidinyl Urea was rated as a grade 2 sensitizer (mild)and displayed variable cross-sensitization to both IMID and FORM. In 1990, Parker documented that independent sensitization occurred with FORM-re- leasing biocides with the exception of DIAZ.[2]

Diazolidinyl urea is a formaldehyde-releasing preservative used in cosmetics and personal- care products, which has been identified as a sensitizing agent in contact dermatitis. To determine whether DIAZ sensitization is secondary to formaldehyde release or due to its own allergenic properties, we reviewed 708 consecutive patch tests of patients with various dermatologic com- plaints. Profiles of the 58 individuals (8%) with DIAZ sensitivitiy were analyzed with respect to sex, age, exposures, and chronicity of dermatitis. Significant coexistent biocide reactivity was demonstrated for DIAZ and formaldehyde (81%); 12%reacted to Diazolidinyl Urea alone. We conclude that the primary mode of sensitization of DIAZ is via formaldehyde release and that independent contact allergy is less frequent.

References

[1]Doi T, Kajimura K, Taguchi S. The different decomposition properties of diazolidinyl urea in cosmetics and patch test materials. Contact Dermatitis. 2011 Aug;65(2):81-91. doi: 10.1111/j.1600-0536.2010.01862.x. Epub 2011 Feb 10. PMID: 21309789.

[2]Hectorne KJ, Fransway AF. Diazolidinyl urea: incidence of sensitivity, patterns of cross-reactivity and clinical relevance. Contact Dermatitis. 1994 Jan;30(1):16-9. doi: 10.1111/j.1600-0536.1994.tb00722.x. PMID: 8156757.

You may like