Contact Dermatitis 2007: 56: 146–150 Printed in Singapore. All rights reserved # 2007 The Authors Journal compilation # 2007 Blackwell Munksgaard CONTACT DERMATITIS Experimental elicitation with hydroxyisohexyl-3- cyclohexene carboxaldehyde-containing deodorants PIA HASLUND JØRGENSEN 1 ,CHARLOTTE DEVANTIER JENSEN 1,2 ,SURESH RASTOGI 3 , KLAUS EJNER ANDERSEN 1,2 AND JEANNE DUUS JOHANSEN 1 1 National Allergy Research Center, Department of Dermatology, Gentofte Hospital, University of Copenhagen, Denmark, 2 Department of Dermatology, Odense University Hospital, University of Southern Denmark, Denmark, and 3 Department of Environmental Chemistry, National Environmental Research Institute, Denmark Hydroxyisohexyl-3-cyclohexene carboxaldehyde (HICC) known as Lyral1 is a frequent allergen. It is used in more than 50% of marketed deodorants. The aim of the present study was to determine elicitation thresholds for HICC under simulated conditions of deodorant use. 15 patients with pre- viously diagnosed contact allergy to HICC were patch tested with 5 solutions of HICC-scented and HICC-unscented deodorants. Patients and 10 healthy controls performed a use test in the axillae using deodorants scented with HICC in increasing concentrations and unscented deodorants as control. The concentration of HICC was increased every second week (200, 600, and 1800 p.p.m.) until either a reaction developed or for 6 weeks. 14 patients completed the study, and all developed unilateral eczema from the HICC-containing deodorant, while controls were all negative (P ¼ 0.004). In 9/14 patients, a positive use test developed during the first 2 weeks to the deodorant containing 200 p.p.m. HICC. Positive correlations were found between the day of positive use and patch test threshold concentration of the HICC solutions (r ¼ 0.71, P ¼ 0.01) as well as the patch test thresholds of the HICC-scented deodorants (r ¼ 0.74, P ¼ 0.007). In conclusion, HICC elicits allergic con- tact dermatitis in a high proportion of sensitized individuals at common usage concentrations in deodorants. Key words: hydroxyisohexyl-3-cyclohexene carboxaldehyde; fragrance allergy; axilla; deodorants; risk assessment; thresholds; Lyral. # Blackwell Munksgaard 2007. Accepted for publication 1 October 2006 Hydroxyisohexyl-3-cyclohexene carboxaldehyde (HICC), also known as Lyral1, is a fragrance constituent in consumer products, such as deo- dorants and perfumes. Among eczema patients in Europe 1.5–3% give a positive patch test to HICC (1–4). Recently, similar frequencies of sen- sitization were found in a multi-centre study in Korea (5), while it seems to be a less frequent fragrance allergen among eczema patients in North America (6). HICC is a synthetic fragrance material, and even though it has been used for decades, it has only recently been identified as an allergen. Knowledge about safe exposure conditions is therefore limited. In a recent clinical study, almost all HICC sensitized eczema patients developed eczema following repeated open applications of HICC on the forearm in concentrations relevant for perfumes (7). HICC is used in more than 50% of deodorants on the market (8); however, no elicitation studies have been performed with HICC-containing deo- dorants in the axilla. The aim of the present study was to determine elicitation thresholds for HICC under simulated use-conditions of deodorants. Methods Subjects 15 patients (14 women, mean age 50 years) pre- viously tested positive to HICC (Lyral1) 5% in petrolatum were recruited from the Department of Dermatology, Gentofte University Hospital and the Department of Dermatology, Odense University Hospital. 10 healthy volunteers (6 women, mean age 25.4 years) were included. For both groups exclusion criteria were pregnancy,