A catch-up validation study on reconstructed human epidermis (SkinEthic RHE) for full replacement of the Draize skin irritation test.

Efforts to fully replace the in vivo Draize skin irritation test, according to the Directive 67/548/ECC or OECD TG 404, were reinforced with the seventh Amendment of the Cosmetic Directive and the REACh regulation. In 2007, the EpiSkin test method was scientifically validated and recognized as the stand alone method to discriminate skin irritants (R38) from non-irritants (no label) according to the definition of the EU risk phrases. An ECVAM performance standards (PS) document was defined to evaluate the accuracy and reliability of other analogous test methods (ECVAM SIVS, May 2007).

Assessment of the optimized SkinEthic Reconstructed Human Epidermis (RHE) 42 bis skin irritation protocol over 39 test substances.

The development of in vitro protocols able to discriminate skin irritants from non-irritants integrates the toxicologists' needs for reliable and robust in vitro tools for screening test substances. Based on EpiSkin test method, validated by ESAC (ECVAM Scientific Advisory Committee) in April 2007 as the Draize skin irritation replacement reference test method, we present and discuss here the results obtained by adapting protocols to the SkinEthic Reconstructed Human Epidermis (RHE) model. The main adaptations of the validated reference protocol consists in a modulated exposure time (15, 42 or 60min) followed by a rinsing step and a 42h post-incubation period before quantitative measurement of cell viability by MTT reduction.