Prevalenza della sensibilizzazione all'olio essenziale di Melaleuca

Background: Melaleuca essential oil, extracted by hydrodistillation front the leaves of Melaleuca alternifolia Cheel or tea tree, is used widely for its antiseptic properties. Its presence in an increasing number of cosmetics, detergents, topical preparations but also in phytodrugs foresees increasingly more widespread use of Melaleuca oil in Italy. Objectives: The aims of our study were to determine the prevalence of delayed sensitivity to Melaleuca and assess the optimum patch test concentration of substance. Materials and methods: 725 consecutive subjects of both sexes (mean age, 43.5 years) were patch tested according to the GIRDCA guidelines; 393 of these suffered front contact dermatitis (allergic in 141, irritant in 252), 35 from atopic dermatitis, and 297 front other skin disorders in whom patch testing was required for diagnostic purposes. An atopy constitution was proven in 169 subjects, but it was clinically relevant only in 134. Patch testing was performed with the SIDAPA/GIRDCA standard series, Melaleuca alternifolia Cheel oil stabilised by microincapsulation (undiluited, 5%, 1% and 0.1% in pet.), Compositae mix and sesquiterpene lactone mix. The results were analysed using χ² test and Student's t-test. Results: in 43 subjects (5.9%) positive reactions to undiluted Melaleuca oil were observed, but they were slight (±/+) in 37 and non-persistent at 96 hours in 14. The serial dilution test was positive until 1% only in 1 subject. The 0.1% dilution was always negative. The positive reactions were more frequent in subjects with allergic contact dermatitis or atopic dermatitis. Conclusions: the sensitization potential of Melaleuca essential oil is poor, at least in Italy and for the time being. The optimum patch test concentration is 1%.