Patch test reactivity to DMDM hydantoin. Relationship to formaldehyde allergy.

Area of Science:

• Dermatology
• Cosmetic Science
• Allergology

Background:

• Formaldehyde is a known contact allergen.
• DMDM hydantoin is a formaldehyde-releasing preservative used in cosmetics.
• The potential for DMDM hydantoin to elicit reactions in formaldehyde-allergic individuals requires investigation.

Purpose of the Study:

• To investigate the relationship between formaldehyde allergy and patch test reactions to DMDM hydantoin.
• To determine if DMDM hydantoin releases sufficient free formaldehyde to cause allergic reactions in sensitized patients.
• To assess the risk of cosmetic dermatitis from DMDM hydantoin use in formaldehyde-allergic consumers.

Main Methods:

• Patch testing 35 formaldehyde-allergic patients with serial dilutions of formaldehyde, DM hydantoin, MDM hydantoin, and DMDM hydantoin.
• Evaluating patient reactions to different concentrations of these substances.
• Conducting a clinical test where 12 formaldehyde-allergic patients applied a cream containing 1% DMDM hydantoin, followed by a cream with 0.25% DMDM hydantoin in a subset.

Main Results:

• 33% of patients reacted to MDM hydantoin and 57% to DMDM hydantoin.
• Patients with lower concentration formaldehyde sensitivity showed higher reactivity to (D)MDM hydantoin.
• Topical application of DMDM hydantoin in a cream caused dermatitis in 33% of tested patients, with lower concentrations still causing reactions.

Conclusions:

• Aqueous solutions of DMDM hydantoin contain enough free formaldehyde to elicit patch test reactions in some formaldehyde-allergic patients.
• Increased use of DMDM hydantoin in cosmetics poses a greater risk of cosmetic dermatitis for individuals allergic to formaldehyde.
• Clinical vigilance and careful formulation are necessary to mitigate risks associated with formaldehyde-releasing preservatives.