RESUMO
This study was undertaken to investigate to compare the ratio of positive reactions to benzoic acid(BA), sorbic acid(SA) and cinnamic acid(CA) which are well known materials producing non-immunologic contact urticaria. Various concentrations(0.l% to 5%) and different vehicles(petrolatum, water, hydrophilic ointment base) were used in open and 20 minutes closed test using Finn chamber on Scanpor tape. One hundred total subjects were consisted of nonallergic patients and normal persons. The results were as follows ; 1. Total numbers of positive reactions were 69 in closed test(CT) and 60 in open test(OT), regardless of the materials and vehicles. 2. Total riumbers of positive reactions in BA, SA and CA were 68, 31, 35 in CT and 59, 20, 14 in OT respectably. 3. CT showed much more positive reactions than OT with all materials tested except 0.l% SA in water. 4. Hydrophilic ointment base showed a better reactivity than any other vehicles in CT. But in OT, petrolatum, water, hydrophilic ointment base showed better reactivity in BA, SA, CA respectably. 5. Almost all the reactions appeared within 45 minutes and disappeared within 3 hours. Erythema preceded edema and persisted 30 minutes to 1 hour after dissappearance of edema. 6 Itching, burning and tingling sensation were the only symptoms observed except. localized erythema and edema.