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The optimal patch test concentration for ascaridole as a sensitizing component of tea tree oil
Author(s) -
Christoffers Wietske Andrea,
Blömeke Brunhilde,
Coenraads PieterJan,
Schuttelaar MarieLouise Anna
Publication year - 2014
Publication title -
contact dermatitis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 96
eISSN - 1600-0536
pISSN - 0105-1873
DOI - 10.1111/cod.12199
Subject(s) - patch test , tea tree oil , traditional medicine , melaleuca alternifolia , allergic contact dermatitis , chemistry , component (thermodynamics) , tree (set theory) , contact dermatitis , dermatology , medicine , chromatography , essential oil , mathematics , allergy , immunology , mathematical analysis , physics , thermodynamics
Summary Background Tea tree oil is used as a natural remedy, but is also a popular ingredient in household and cosmetic products. Oxidation of tea tree oil results in degradation products, such as ascaridole, which may cause allergic contact dermatitis. Objectives To identify the optimal patch test concentration for ascaridole, and to investigate the relationship between a positive reaction to ascaridole and a positive reaction to oxidized tea tree oil. Patients/materials/methods Three hundred and nineteen patients with eczema were patch tested with ascaridole 1%, 2%, and 5%, and 250 patients were patch tested with oxidized tea tree oil 5%. Readings were performed on D3 and D7 according to a patch test calibration protocol. Results With an increasing ascaridole test concentration, the frequency of positive reactions increased: ascaridole 1%, 1.4%; ascaridole 2%, 5.5%; and ascaridole 5%, 7.2%. However, the frequencies of irritant and doubtful reactions also increased, especially for ascaridole 5%. A positive reaction to ascaridole was related to a positive reaction to tea tree oil. Conclusions This study is in support of ascaridole being a sensitizer. We recommend patch testing with ascaridole at 2%. The finding that every positive reaction to oxidized tea tree oil is accompanied by a positive reaction to ascaridole suggests that ascaridole might be a contact allergen in oxidized tea tree oil.