The Globally Harmonised System for the classification and labeling of chemical substances and mixtures (GHS) defined skin corrosion as the productionof irreversible tissue damage in the skin. In vitro human reconstructed epidermal EpiSkinTM and SkinEthicTM RHE models have been used to developprotocols able to discriminate corrosives from non corrosives , were scientifically validated and adopted.EpiSkin 1996: ECVAM prospective validation using 60 chemicals mixtures 1998: ESAC statement on the scientific validity of the test method ICCVAM review on ? 2000: EU Test methods B40 bis acceptance 2004: OECD adoption of the Test Guideline 431in vitro dermal corrosivity methods Distinction between corrosive and non-corrosive chemicals, and also between known R35 (UN packing group I, GHS cat1A) and R34 (UN packing group II & III, GHS cat 1B/1C) SkinEthic RHE 2006: Performance standard-based validation using 20 chemicals 2006: ESAC statement on the scientific validity of the test method 2010: Adoption of the skin corrosion test method to 0.5cm2 RHE tissuesSkin corrosion: background • During the international validation study, both in vitro test methods for skin corrosivity were reproducible, within and between the three laboratories involved. • The test methods proved to be applicable for the testing a diverse group of chemicals of different physical forms, including organic acids, organic bases, neutral organics, inorganic acids, inorganic bases, inorganic salts, electrophiles, phenols and soaps/surfactants… • • The concordances between the skin corrosivity classifications derived from the in vitro data and from the in vivo data were very good (Table 1). EpiSkinTM was also able to distinguish between known R35 (UN packing group I) and R34 (UN packing groups II & III) chemicals.