Development of an in vitro corrosion/irritation prediction assay using the EpiDerm™ skin model

A validation of the in vitro skin corrosion method using the EpiDerm™ skin model was performed using 12 recommended chemicals. All chemicals were correctly classified by OECD test guideline 431. In order to predict corrosion and/or irritation potential, additional compound exposure times and IL-1α measurements were included in a tiered testing approach.Four exposure times were performed followed by MTT (viability) and IL-1α measurement. This allowed classification of corrosive chemicals (OECD guideline 431) and those likely to be severe irritants. If the chemical was found to be corrosive or a severe irritant, no further experimental work was performed, otherwise a second experiment was performed using three further exposure times (same endpoints). The second experiment provided information on whether the chemical was likely to be a moderate/mild irritant. If the chemical was negative following both experiments, it was predicted as non-corrosive/non-irritating.A total of 12 chemicals were tested in the irritation or combined assay (five non-irritants, seven irritants). Specificity (% non-irritants concurring with EU classification) was 60% (MTT) and 100% (MTT + IL-1α). Sensitivity (% irritants concurring with EU classification) was 86% (MTT) and 86% (MTT + IL-1α). Accuracy (% chemicals correctly identified) was 75% (MTT) and 92% (MTT + IL-1α).