Adaptation of the validated SkinEthic Reconstructed Human Epidermis (RHE) skin corrosion test method to 0.5 cm2 tissue sample

At its 25th meeting the ECVAM Scientific Advisory Committee (ESAC) unanimously endorsed that the SkinEthic Reconstructed Human Epidermis (RHE) model could be used for distinguishing between corrosive and non-corrosive chemicals within the context of the Organisation Economic for Co-operation and Development (OECD) test guideline, TG 431 (ESAC 16-17 November 2006). Both test method development and multi-center study were performed using 0.63 cm(2) RHE tissue samples. The purpose of the present study was to demonstrate that similar results could be obtained using the validated test method adapted to 0.5cm(2) RHE tissue samples. Test method adaptation only consisted in applying a reduced volume of test substance (40 microL instead of 50 microL for liquids and 20 microL water+20mg test substance instead of 25 microL water+25mg test substance for solids) and a reduced propan-2-ol extraction volume (1.5 mL instead of 2 mL) during the MTT reduction assay. The test method was assessed with 25 representative test substances of different chemical classes. Among the latter, the 12 OECD reference test substances (6 corrosives and 6 non-corrosives) were evaluated and showed to be similarly classified as in vivo. More generally, the SkinEthic skin corrosion test adapted to 0.5 cm(2) RHE tissue samples fully complies with the OECD performance and reproducibility requirements with the 25 test substances.