title: Nonanoic acid irritation - a positive control at routine patch testing?
abstract: A false negative patch test can be related to errors in the testing procedure, or to a defect in the eliciting (efferent) phase of the immune response. To define this phase the application of a topical irritant (a "positive control") is suggested. Various concentrations of nonanoic acid in 1-propanol were applied to 116 healthy volunteers and to 75 dermatitis patients. Dose-response curves were obtained (concentrations 5, 10, 20 and 39.9%). Twenty percent nonanoic acid produced skin reactions in 90.1--93.9% of the subjects. The lesions consisted mainly of erythema at 48 h and pigmentation at 96 h. We suggested that the most interesting patients are those negative to this primary irritant and thay they should be further evaluated.
mesh_terms: D000328:Adult; D000368:Aged; D004305:Dose-Response Relationship, Drug; D004890:Erythema / Q000139:chemically induced; D005227:Fatty Acids / Q000009:adverse effects*; D005230:Fatty Acids, Nonesterified / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D012015:Reference Standards; D012107:Research Design; D012882:Skin Tests
chemical_list: D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; C008776:pelargonic acid