Contact allergy to fragrances. With a focus on hydroperoxides of linalool and hydroperoxides of limonene

Sammanfattning: Patch testing with fragrance allergens has been performed for over half a century, and the protocol has been continually developed and standardised. Fragrance mixes I and II and Myroxylon pereirae resin are commonly used as screening fragrance allergens in patch testing.During the past few decades, linalool and limonene hydroperoxides have emerged as contact allergens as a result of high rates of positive patch test reactions worldwide. Including these two allergens in the baseline series for fragrance contact allergy screening in consecutive patients has been the subject of debate because it is difficult to establish the sources of allergen exposure and definite clinical relevance.Two major problems that remain to be solved are the discrepancies of patch testresults between fragrance mixes and their individual ingredients, and the assessment of clinical relevance in patients with contact allergy to hydroperoxides of linalool and hydroperoxides of limonene regarding uncertain sources of exposure.The main objective of the work presented in this thesis was to improve the diagnostic procedures for fragrance contact allergy and allergic contact dermatitis, focusing on the hydroperoxides of linalool and hydroperoxides of limonene. Studies were carried out to determine the prevalence and demographics of fragrance contact allergy, and to update information on patch test results and patterns of simultaneous reactions. Repeated open application tests were also performed in patients with contact allergy to hydroperoxides of linalool.The findings of these studies can be summarized as follows. Patients with single fragrance contact allergy or who showed a weak reaction to the individual ingredients of the fragrance mixes were missed when patch tested with only fragrance mixes in the baseline series. The interpretation of patch test results using patch test preparations containing sorbitan sesquioleate remains problematic. Contact allergies to the hydroperoxides of linalool and hydroperoxides of limonene are increasing. The rates of contact allergies to these two culprits are significantly more common in a younger group than contact allergies to other fragrances. Repeated open application tests with creams containing hydroperoxides of linalool at the realistic concentrations reported in products rarely elicited skin reactions.