title: Positive patch test reactions to oxidized limonene: exposure and relevance.
abstract: BACKGROUND
  R-Limonene is a common fragrance terpene found in domestic and industrial products. R-Limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a recent multicentre study, 5.2% (range 2.3-12.1%) of 2900 patients showed a positive patch test reaction to oxidized R-limonene.
  
  
  OBJECTIVE
  To study the exposure to limonene among consecutive dermatitis patients reacting to oxidized R-limonene in an international setting, and to assess the relevance of the exposure for the patients' dermatitis.
  
  
  METHODS
  Oxidized R-limonene 3.0% (containing limonene hydroperoxides at 0.33%) in petrolatum was tested in 2900 consecutive dermatitis patients in Australia, Denmark, the United Kingdom, Singapore, Spain, and Sweden. A questionnaire assessing exposure to limonene-containing products was completed.
  
  
  RESULTS
  Overall, exposure to products containing limonene was found and assessed as being probably relevant for the patients' dermatitis in 36% of the limonene-allergic patients. In Barcelona and Copenhagen, > 70% of the patients were judged to have had an exposure to limonene assessed as relevant.
  
  
  CONCLUSIONS
  Oxidized R-limonene is a common fragrance allergen, and limonene was frequently found in the labelling on the patients' products, and assessed as relevant for the patients' dermatitis. A large number of domestic and occupational sources for contact with R-limonene were identified.
authors.affiliation: Department of Dermatology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden; Dermatochemistry and Skin Allergy, Department of Chemistry and Molecular Biology, University of Gothenburg, 412 96 Gothenburg, Sweden.
authors.forename: Johanna
authors.initials: J
authors.lastname: Bråred Christensson
authors.forename: Klaus E
authors.initials: KE
authors.lastname: Andersen
authors.forename: Magnus
authors.initials: M
authors.lastname: Bruze
authors.forename: Jeanne D
authors.initials: JD
authors.lastname: Johansen
authors.forename: Begoña
authors.initials: B
authors.lastname: Garcia-Bravo
authors.forename: Ana
authors.initials: A
authors.lastname: Gimenez Arnau
authors.forename: Chee-Leok
authors.initials: CL
authors.lastname: Goh
authors.forename: Rosemary
authors.initials: R
authors.lastname: Nixon
authors.forename: Ian R
authors.initials: IR
authors.lastname: White
mesh_terms: D053138:Cyclohexenes / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000209:etiology*; D005260:Female; D006795:Household Products / Q000009:adverse effects; D006801:Humans; D000077222:Limonene; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects; D010084:Oxidation-Reduction; D010328:Patch Tests; D010476:Perfume / Q000009:adverse effects; D013729:Terpenes / Q000009:adverse effects*
chemical_list: D053138:Cyclohexenes; D010476:Perfume; D013729:Terpenes; D000077222:Limonene
keywords: allergic contact dermatitis; autoxidation; fragrance allergy; hydroperoxide; limonene; oxidation products; patch test; relevance; terpenes