The EpiDerm Skin Corrosion Test (EpiDerm SCT)

The potential for chemical induced skin corrosion is an important consideration in establishing procedures for the safe handling, packing and transport of chemicals. Various systems for classification of corrosive potential are included in international regulatory requirements. The EpiDerm^TM Skin Corrosion Test (SCT) is based on the experience that corrosive chemicals are cytotoxic after a short-term exposure to the stratum corneum of the epidermis, if cytotoxicity is immediately determined after chemical exposure. It is designed to predict and classify skin corrosion potential of chemicals by using a three-dimensional human epidermis model EpiDerm^TM. The EpiDerm^TM SCT is able to reliably discriminate chemicals that are corrosive to skin from non-corrosive chemicals, and can therefore be used for the classification of skin corrosion hazard according to the UN Globally Harmonised System (GHS) for classification [1]. The EpiDerm^TM SCT with its modification of the Prediction model can be also used to distinguish between sub-categories of corrosivity [2–4]. The EpiDerm^TM SCT has been scientifically described for the first time by Perkins et al. [5], later on evaluated, optimized and in its final form validated by ZEBET at the BfR in the framework of ECVAM activities. In order to replace the skin corrosion test in animals, ECVAM has in the 1990s supported twice a formal validation study for predicting skin corrosion by alternative methods. The first validation study [6], conducted between 1995 and 1997, was performed with two commercially available in vitro test systems, the Skin2 ZK1350 and EPISKIN^TM and it also included two other methods CORROSITEX (analytical assay) and TER test (ex vivo method). The TER test [7] and both skin model assays have shown usefulness for corrosion testing, however of the skin model assays only EPISKIN^TM was considered as assay fully meeting the acceptance criteria set by the Management Team [8]. Unfortunately, the Skin2 model was withdrawn from the market very shortly after the ECVAM validation study without possibility of method optimization. Also, the commercial availability of EPISKIN^TM model (at that time belonging to SADUC-Biomatériaux Imedex, France) was restricted following the completion of the validation study. It was due to the transfer of the ownership of the EPISKIN^TM technology from Imedex to L’Oréal and construction of new production laboratories in Lyon-Gerlan. Due to the lack of commercial availability of the validated methods for the skin corrosion endpoint, ECVAM supported a catch-up validation study of the EpiDerm^TM SCT in 1998. The study was performed according to the ECVAM pre-validation scheme, to allow for refinement of the test protocol and the prediction model, as well as for independent assessment of the performance of the refined methodology in a final blind trial in three laboratories [9]. The validation study revealed that the EpiDermTM SCT protocol provided a highly balanced prediction of 88% sensitivity and 86% specificity, which was regarded as the best predictivity that an in vitro skin corrosivity test could be expected to achieve [9] taking into account the inherent variability of the in vivo reference test [6]. Based on the successful validation studies with EPISKIN^TM and EpiDerm^TM models [8, 10], in 2002 the National Coordinators of OECD Test Guideline Programme (WNT) endorsed New Draft Test Guidelines TG 431 (Human Skin Model) for In Vitro Skin Corrosion Testing which was originally adopted by the OECD in 2004 [4]. The EpiDerm^TM SOP has been successfully transferred to and validated with the SkinEthicTM RHE [11, 12] and EST-1000 [13, 14]. The two models, that underwent catch-up validation studies were also endorsed for skin corrosion testing and later on implemented into the OECD TG 431 [4]. The OECD TG 431 initially allowed only discrimination between corrosive and non-corrosive chemicals, however in light of the REACH and transport regulations, and after thorough analysis of all available data from EPISKIN^TM, EpiDerm^TM, SkinEthic^TM and EST-1000 validation studies and new data generated by the skin models suppliers [3] the OECD updated the OECD TG 431 concerning sub-categorisation information of corrosives [4].

EpiDerm Skin Corrosion Test, GHS sub-categories, Sub-categorization, Inter-laboratory reproducibility, OECD TG 431

Potassium Hydroxide (8N)