Potenziale sensibilizzante di alcuni concianti vegetali e di alcune pelli conciate al vegetale.

Background: foot eczema is caused by shoe contact allergy in 3-11% of the cases. The most common sensitizers are represented by rubber, adhesives, chemical tans, dyes, several biocides and, the last but not the least, metal accessories. Vegetable tans would be less important than chromium salts in the etiology of footwear allergic contact dermatitis. However, few studies have been made on their sensitization potential. Objectives: the two goals for this study were to determine a) the optimal patch testing concentration for the four most widely used and rich of tannins vegetable tans (chestnut, mimosa, quebracho and tara) and b) the prevalence of irritant and allergic reactions to the four vegetable tans and two vegetable-tanned skins (sole leather, vacchetta). Materials and Methods: in phase 1 find the optimal patch testing concentration of the four vegetable tans diluted in petrolatum; this was evaluated by a serial dilution test (5, 2 and 1%) in 100 subjects with various skin diseases. In phase 2, sensitization and irritation potential of the four vegetable tans in petrolatum 2% and the two vegetable-tanned skins were investigated in 563 patients patch tested for eczematous dermatitis or any suspected allergic skin disorder. Results and discussion: the study demonstrates that optimal concentration to test vegetable tans in petrolatum is 2% and that delayed positive reactions to tans are very rare (0.4%) and not clinically relevant, while those to vegetable-tanned skins (1.2%) are more frequent but probably relevant only in 3 of the 7 patients. These last three cases were not associated to positive patch tests to single tan; therefore, they could be due to preservatives, chemical contaminants or reaction compounds introduced accidentally during the production cycle.