Test No. 439: In Vitro Skin Irritation
Reconstructed Human Epidermis Test Method
This Test Guideline describes an in vitro procedure that may be used for the hazard
identification of irritant chemicals (substances and mixtures) in accordance with
the UN Globally Harmonized System of Classification and Labelling (GHS) Category 2.
It is based on reconstructed human epidermis (RhE), which in its overall design closely
mimics the biochemical and physiological properties of the upper parts of the human
skin. Cell viability is measured by enzymatic conversion of the vital dye MTT into
a blue formazan salt that is quantitatively measured after extraction from tissues.
Irritant test substances are identified by their ability to decrease cell viability
below defined threshold levels (below or equal to 50% for UN GHS Category 2). This
Test Guideline also includes a set of Performance Standards for the assessment of
similar and modified RhE-based test methods. There are three validated test methods
that adhere to this Test Guideline. Depending on the regulatory framework and the
classification system in use, this procedure may be used to determine the skin irritancy
of test substances as a stand-alone replacement test for in vivo skin irritation testing,
or as a partial replacement test, within a tiered testing strategy.
Published on July 23, 2010Also available in: French