Positive patch test reactions to oxidized limonene: exposure and relevance

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.