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-1alpha measurements were included in a tiered testing approach. Four exposure times were performed followed by MTT (viability) and IL-1alpha 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-1alpha). Sensitivity (% irritants concurring with EU classification) was 86% (MTT) and 86% (MTT+IL-1alpha). Accuracy (% chemicals correctly identified) was 75% (MTT) and 92% (MTT+IL-1alpha).