Limonene is a fragrance widely used in cosmetics and household products. Until recently, contact allergy to limonene was considered rare because positive patch tests to it were infrequently observed. In recent years, however, it has been demonstrated that exposure of limonene to oxygen (air) results in the formation of a number of oxidation products, of which the hydroperoxides have a far stronger sensitizing potency than the pure compound. By routine testing of patients suspected of contact dermatitis with hydroperoxides of limonene, high frequencies of positive reactions were found, indicating that these chemicals are important fragrance allergens. It should be realized, however, that a number of “positive” reactions may well be false-positive, irritant responses.
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Address reprint requests to Anton de Groot, MD, PhD, Schipslootweg 5, 8351 HV Wapserveen, the Netherlands. E-mail: firstname.lastname@example.org.
The author has no funding or conflicts of interest to declare.
Anton de Groot is the author of the book Monographs in Contact Allergy, Volume II—Fragrances and Essential Oils. Boca Raton, FL: CRC Press Taylor & Francis Group; 2019, to which is referred repeatedly in this article.
Online date: August 20, 2019