Anatomical site differences of SLS‐induced ICD

Abstract

Sodium lauryl sulphate (SLS) is a chemical used to induce skin irritation that mimics irritant contact dermatitis (ICD). ICD is a condition where direct contact with certain substances causes rash, redness, blistering, itching, dryness and cracking of the exposed skin. It is a common occupational disease and accounts for 4‐7% of all dermatological consultations in U.K. This SLS induced irritation is often used to test the effectiveness of different treatments that could be used to alleviate the ICD symptoms. Irritation is usually induced on the forearms but other locations such as upper back have been used. The extent of the irritation might be different between different anatomical locations. Those differences could affect the results of the treatment testing. That means that the beneficial effects achieved by the treatment on one location may not be achieved on the other. This study, from Croatia, aimed to investigate variations in skin response to irritation and its effects on treatment in an SLS induced ICD. The irritant was applied on the forearms and the upper back of the healthy volunteers. Emollient (moisturising) cream was chosen as a treatment. One forearm and one side of the back were treated with the emollient for nine days while others were left untreated. The skin parameters that indicate the extent of the irritation and the recovery were measured using skin probes. The authors found that the upper back had stronger reaction to the irritant and faster recovery of the skin than the forearms. Also, the tested emollient cream did not improve the skin recovery. In conclusion, the anatomical location is an important factor influencing the results of the studies testing treatment effectiveness. Future studies should always accurately report the testing location. The results of the studies using this irritation model, but on different anatomical locations, are not necessarily directly comparable.