3. How are in vitro skin irritation and corrosion tests conducted?

3.1 In vitro" skin irritation

OECD test no. 439: in vitro skin irritation reconstructed human epidermis test method. Principle: "The test substance is applied topically to a three-dimensional model of reconstructed human epidermis, composed of untransformed keratinocytes taken from human epidermis and cultured to form a highly differentiated multilayer model of human epidermis. This model is composed of organized layers (basal, spinous and granular), as well as a multilayered stratum corneum containing intercellular lamellar lipid layers representing the main lipid classes, similar to those observed in vivo. The cell viability...