Linalool--a significant contact sensitizer after air exposure

Area of Science:

• Dermatology
• Allergology
• Chemical Sensitization

Background:

• Linalool, a common fragrance terpene, can cause contact allergy after oxidation.
• Previous patch testing showed 1.3% positive reactions to oxidized linalool at 2.0% in petrolatum.
• Oxidized linalool's allergenic potential necessitates optimized diagnostic methods.

Purpose of the Study:

• To determine the optimal patch test concentration for detecting contact allergy to oxidized linalool.
• To evaluate the dose-response relationship of oxidized linalool concentrations in patch testing.

Main Methods:

• Consecutive dermatitis patients (n=3418) underwent patch testing.
• Four concentrations of oxidized linalool in petrolatum (2.0%, 4.0%, 6.0%, 11.0%) were applied.
• Reactions were assessed for positive, doubtful, and irritative responses.

Main Results:

• Positive patch test reactions increased with higher oxidized linalool concentrations.
• Rates of positive reactions were 0.83% (2.0%), 3.2% (4.0%), 5.3% (6.0%), and 7.2% (11.0%).
• Doubtful and irritative reactions were observed but generally manageable.

Conclusions:

• Increasing oxidized linalool concentration enhances contact allergy detection, identifying 5-7% positive reactions.
• A 6.0% oxidized linalool in petrolatum concentration is proposed for future patch testing.
• This concentration provides a dose of 2.4 mg/cm² for effective allergy screening.