Dermal Irritation in 3-Dimensional Reconstructed Human Epidermis Tissues: EpiDerm, epiCS, EpiSkin and SkinEthic RCE
Test Material Compatibility
The EpiDerm, epiCS, EpiSkin and RHE are compatible with solid and liquid test materials as well as for water/solvent soluble and insoluble formulations. Since test materials are topically applied, the test systems are suitable for creams, pastes, highly viscous materials, and powders.
Assays and Endpoints
Time to Toxicity. Potential dermal irritation of a test material is evaluated using a time to toxicity approach, where several exposure times are tested and an ET50 value (the exposure time required to reduce tissue viability by 50%) is determined.
Skin Irritation Test (SIT). Potential skin irritants are evaluated using a single fixed exposure time protocol. Test results are used to label and package test materials as skin irritant or non-irritant, according to the Globally Harmonized System (GHS 2). IIVS participated in the pre-validation and validation studies that led to the adoption of the OECD Test Guideline 439: In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method (TG 439).
Dermal Corrosivity. Potential dermal corrosivity of a test material is evaluated using two fixed exposures to differentiate between corrosives and non-corrosives, as well as to sub-categorize among GHS corrosive classes 1A and 1B/1C. For more information, see OECD Test Guideline 431 “In Vitro Skin Corrosion: Human Skin Model Test”.
Phototoxicity in 3-Dimensional Tissues. The potential phototoxicity of a test material is evaluated by comparing the relative reduction in viability of 3-D tissues after exposure to a test material either in the presence or absence of UVA exposure. For more information on phototoxicity testing, see Phototoxicity.
Potential Irritancy Using Cytokine Release, Induction and Expression. Cytokine expression analysis can be included as an additional endpoint to help evaluate the degree of dermal irritation induced by a test material. Pro-inflammatory activity may be determined by the synthesis/release of cytokines including IL-1 alpha , IL-1ra, TNF-alpha, IL-8, and others.
Various commercial human reconstructed epidermal models have been validated by ECVAM and ICCVAM for corrosivity (OECD TG 431), and for skin irritation potential (OECD TG 439).