Contact allergy to essential oils cannot always be predicted from allergy to fragrance markers in the baseline series.

BACKGROUND: Essential oils are fragrance substances that are labelled on cosmetic products by their INCI names, potentially confusing consumers. OBJECTIVES: To establish whether contact allergy to essential oils might be missed if not specifically tested for. METHODS: We tested 471 patients with 14 essential oils and 2104 patients with Melaleuca alternifolia oil between January 2008 and June 2014. All patients were tested with fragrance mix I, fragrance mix II, hydroxyisohexyl 3-cyclohexene carboxaldehyde, and Myroxylon pereirae. Three hundred and twenty-six patients were tested with hydroperoxides of limonene and linalool. RESULTS: Thirty-four patients had a +/++/+++ reaction to at least one essential oil. Eleven had no reaction to any of the six marker fragrance substances. Thus, 4 of 11 positive reactions to M. alternifolia oil, 2 of 7 reactions to Cymbopogon flexuosus oil, 1 of 5 reactions to Cananga odorata oil, 3 of 4 reactions to Santalum album oil and 2 of 3 reactions to Mentha piperita oil would have been missed without individual testing. CONCLUSION: A small number of patients who are allergic to essential oils could be missed if these are not specifically tested. Labelling by INCI names means that exposure may not be obvious. Careful inspection of so-called 'natural' products and targeted testing is recommended.

Safety assessment of Ylang-Ylang (Cananga spp.) as a food ingredient.

Ylang-Ylang oil is used in the food industry as a flavor ingredient. It is a complex chemical mixture in the form of an essential oil extracted by water or water-and-steam distillation from the fresh flowers of Cananga odorata Hook. f. & Thomson. Ylang-Ylang oil has been reported to cause dermal sensitization reactions in animals and humans, but it is unclear what constituent(s) within the essential oil comprise the offending agent(s) and whether some Ylang-Ylang oils that have had certain constituent(s) removed are any less prone to cause such allergic reactions. There is no indication in the literature that food exposure to Ylang-Ylang oil has caused allergic reactions. One subchronic inhalation toxicity study, involving Ylang-Ylang oil as part of a larger fragrance raw materials mixture, gave no indication of causing adverse effects, but the relevance to risk assessment of oral food flavoring use exposures is likely minimal. No further toxicity data for Ylang-Ylang oil have been reported. Notwithstanding the foregoing, Ylang-Ylang oil has a long history of fragrance and food flavoring use, with no indication that its estimated consumption from food flavoring use (0.0001 mg/kg/day) has led to any adverse human health effects. These data indicate that at the current level of intake as a food ingredient, Ylang-Ylang oil does not pose a health risk to humans.

Essential Oils, Part IV: Contact Allergy.

Nearly 80 essential oils (including 2 jasmine absolutes) have caused contact allergy. Fifty-five of these have been tested in consecutive patients suspected of contact dermatitis, and nine (laurel, turpentine, orange, tea tree, citronella, ylang-ylang, sandalwood, clove, and costus root) showed greater than 2% positive patch test reactions. Relevance data are generally missing or inadequate. Most reactions are caused by application of pure oils or high-concentration products. The clinical picture depends on the responsible product. Occupational contact dermatitis may occur in professionals performing massages. The (possible) allergens in essential oils are discussed. Several test allergens are available, but patients should preferably be tested with their own products. Co-reactivity with other essential oils and the fragrance mix is frequent, which may partly be explained by common ingredients. Patch test concentrations for essential oils are suggested.