The Globally Harmonised System for the Classification and Labelling of Chemicals defines skin corrosion as the production of irreversible tissue damage in the skin following the application of a test material.
The test material (150 µL for liquids or solid with 150 µL of deionised water added on the top) is applied for up to 24 hours to the epidermal surfaces of skin discs (three skin discs are used for each test and control substance) in a two-compartment test system in which the skin discs function as the separation between the compartments. The skin discs are taken from humanely killed rats aged 28-30 days. Corrosive materials are identified by their ability to produce a loss of normal stratum corneum integrity and barrier function, which is measured as a reduction in the TER below a threshold level (5kΩ for rat). A dye-binding step incorporated into the test procedure permits to determine if the increase in ionic permeability is due to physical destruction of the stratum corneum.
