In vitro EpiSkin skin corrosion as a reference test method in OECD TG431 for the assessment of skin corrosion in sub-categories 1A, 1B and 1C

Skin corrosion or irritation refers to the production of irreversible or reversible damage to the skin following the application of a test substance, respectively. An effective way of predicting test substance toxicity is to make use of testing strategies which incorporate a range of alternative test methods. For the determination of skin irritation and corrosion, hazard assessments for both endpoints could be conducted using in vitro test methods that have been regulatory accepted (OECD TG431 & TG439). In the present study, skin irritation and corrosion evaluations were performed on reconstructed human Epidermis (RhE) models i.e. EpiSkin and SkinEthic RHE. In the case of skin corrosion, GHS guidelines differentiate between non corrosive (NC) to corrosive (C) substances with 3 subcategories: 1A, 1B and 1C. The current evaluation of the test method was performed on 81 test substances from a wide range of chemical for each subcategory class (38 NC, 31 Cat1B/1C and 12 Cat1A) enlarging the evidence base associated with this method. Using the EpiSkin test method, within-laboratory variability (>87%) was assessed in 3 runs. Therefore a sensitivity of 98% and overall accuracy of 89% (with an accuracy of 1A, 1B/1C, NC of 79%) were obtained. The test method able to discriminate 1A, from 1B and 1C classes with the highest well -prediction rate for sub-categorize the substances in comparison with the others validated methods, was submitted to OECD for scientific review and adoption. Adoption of the EpiSkin seems sufficient to fill the gaps in terms of sub-categorisation predictions leading to a significant impact on the sub-group transport package labeling.