A Comparison Study on the Skin Irritation and Recovery by Irritants

Kim, Hyun Wook; Park, Chun Wook; Lee, Cheol Heon

Abstract

BACKGROUND
Corrosive irritants can be defined as irritants which in provoked weak reactions or subclinical reactions induce impairment of the water barrier function and increase of transepidermal water loss (TEWL) while non-corrosive irritants can be defined as irritancy of low degree but with no increase of TEWL. Sodium lauryl sulfate (SLS) has been considered as the standard example of corrosive irritant and nonanoic acid (NAA) is an example of a noncorrosive irritant. OBJECT: This study was done to evaluate the skin irritation and recovery by corrosive and non-corrosive irritant in normal human subjects. METHODS: 0.1, 0.2, 0.5, 1, 2, 5% solution of SLS and 1, 2, 5, 10, 20, 50% solution of NAA were applied on volar forearm skin in 15 normal healthy subjects. TEWL and Erythema index (E-index) were measured at before (BL), 30 minutes (D0), 1st day (D1), 2nd day (D2), 1st week (W1), 2nd week (W2), 3rd week (W3) after the removal of the patches. RESULTS: Increase of TEWL was accelerated according to concentrations in cases of SLS, whereas increase of TEWL according to concentrations was very weak in cases of NAA. SLS induced a significantly higher TEWL increase than NAA at corresponding concentrations. In both SLS and NAA, E-index was increased according to concentrations with no difference in reaction pattern. SLS and NAA induced similar degrees of E-index at corresponding concentrations. TEWL value was highest at 30 minutes and 1 day after removal of the patch in both SLS and NAA. TEWL was recovered to baseline value at 2 weeks after removal of the patch test in case of low concentrations, at 3 weeks after removal of the patch in case of high concentrations. E-index value was highest at 30 minutes, 1 day, and 2 days after removal of the patch in both SLS and NAA. The period of recovery to baseline varied depending on the concentrations. E-index was recovered to baseline value at 1 day after removal of the patch test in case of low concentrations, and was not recovered to baseline value after 3 weeks in case of high concentrations. CONCLUSION: Corrosive irritant, SLS, showing similar degree of erythema with non-corrosive irritant, NAA, induced much more damage to stratum corneum barrier function at corresponding concentrations. Skin injuries induced by corrosive irritants would need more prolonged recovery time than skin injuries by non-corrosive irritants, and TEWL measurement would be even more sensitive than E-index measurement in case of corrosive irritants, while both TEWL and E-index measurement could be useful in case of non-corrosive irritants.