The OECD Test Guideline 431 describes an in vitro method used for evaluating the skin corrosion potential of chemicals using a reconstructed human epidermis (RhE) as the test system. Skin corrosion is defined as an irreversible damage to the skin, observed as visible necrosis through the epidermis and into the dermis following exposure to the test chemical. The method can be used to distinguish corrosive from non-corrosive substances and mixtures in accordance with the applicable UN GHS classification framework, and may also support partial sub-categorisation of corrosive chemicals.

The test involves the use of a 3D reconstructed human epidermis model comprising cultured non-transformed, human-derived epidermal keratinocytes that form a multi-layered, highly differentiated structure similar to the upper layers of human skin. The model contains the epidermal strata of basal, spinous and granular and a multilayered stratum corneum.

The assay is based on the principle that corrosive chemicals can penetrate the stratum corneum by diffusion or erosion and induce cytotoxicity in the underlying cell layers, and therefore, employs an MTT test to determine cell viability. Corrosive chemicals are defined as those that reduce tissue viability to below certain levels.

Vipragen Biosciences offers in vitro skin corrosion testing in accordance with OECD TG 431 using reconstructed human epidermis-based test methods as part of its in vitro safety assessment services.