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The contact urticaria syndrome has at least three separate mechanisms: immunologic (type A), nonimmunologic (type B), and uncertain or undetermined (type C). Dr Lahti has added greatly to our information on the biology of the nonimmunologic-type contact urticaria (NICU).
The phenomenon is extremely common with many simple, widely used chemicals. The nonimmunologic contact urticaria syndrome was caused by 5% benzoic acid, 5% cinnamic acid, and 2½% sorbic acid in petrolatum in 88%, 85%, and 58%, respectively, of a large test panel. After determining the threshold response eliciting wheal and flare reactions, Dr Lahti determined that neither adhesive cellophane tape stripping nor scratching the skin enhanced the reaction. Atopic subjects were no more liable to experience NICU than normal individuals.
The optimum time for gathering results was 45 minutes after the application of the test substances. The back and extensor surfaces of the upper and lower parts of both arms were