Dose-response Evaluation Using an Epidermal Model, an Alternative to Skin Irritation Testing

Using 3-dimensional cultured human skin and epidermal models, an alternative to skin irritation testing have been developed. In the ECVAM (European Centre for the Validation of Alternative Methods) validation protocol, hazardous chemicals have been identified using these models. We considered it likely that these models would also be useful for examining the dose-response of the toxicity of a chemical. Therefore, we used the epidermal model (Labcyte, Japan Tissue Engineering Co. Ltd.) to evaluate the dose-response of cytotoxicity and compared the findings with those for irritancy by human patch testing of 4 chemicals: sodium lauryl sulfate, benzethonium chloride, nonanoic acid and propylene glycol. The cytotoxicity of the chemicals was found to be stronger than the irritancy shown by human patch data. Difference ratios ranging from 1.4 to 52.7 were found between irritancy and EC50(concentration causing a 50% reduction in the MTT assay compared to the untreated control value) in LabCyte for 4 chemicals and solvents. We consider that these models are useful for evaluating the dose-response of skin irritancy, and could be used to establish a database for risk assessment of chemicals.