Limonene, one of the most often used fragrance
terpenes in any kind of scented products, is prone to air-oxidation. The oxidation products formed have a considerable sensitizing potential. In previous patch test studies on consecutively tested
dermatitis patients, oxidized
R-limonene has been proven to be a good and frequent
indicator of fragrance-related contact
allergy. The current study extends these investigations to 6 European clinics of dermatology, where the oxidation mixture of both enantiomers of
limonene (R and S) have been tested in 2411
dermatitis patients. Altogether, 63 out of 2411 patients tested (2.6%) reacted to 1 or both the oxidized
limonene preparations. Only 2.3% reacted to the oxidized
R-limonene and 2.0% to the oxidized S-
limonene. In 57% of the cases, simultaneous reactions were observed to both oxidation mixtures. Concomitant reactions to the fragrance mix,
colophonium, Myroxylon pereirae, and fragrance-related contact
allergy were common in patients reacting to 1 or both the oxidized
limonene enantiomers. Our study provides clinical evidence for the importance of oxidation products of
limonene in contact
allergy. It seems advisable to screen consecutive
dermatitis patients with oxidized
limonene 3%
petrolatum, although this patch test material is not yet commercially available.