Delayed time course of irritation by sodium lauryl sulfate: Observations on threshold reactions

Abstract
Irritant reactions to sodium lauryl sulfate were induced on the backs of 20 [human] volunteers by patch test occlusion for 24 h. Different concentrations ranging from 0.25-2% were used, the lowest concentration being borderline irritant. The skin tests were read at 24, 48 and 72 h. Both the % of responding individuals and the intensity of the skin reactions were maximal at 48 h for all test concentrations. Irritants may provoke inflammatory reactions which are not completely developed after 24 h, and are very similar to allergic patch test reactions.