Surfactants are known to disrupt membrane integrity, leading to skin irritations such as erythema, dryness, and itching. Hence, evaluation of irritation potential of surfactants and surfactant containing formulations is essential to ensure safety of consumers. In this study, in vitro tests were conducted in parallel with in vivo human patch test to predict irritation induced by surfactants. Then, the irritation potential of body cleanser composition formulated with milder surfactants based on the results of ingredients were evaluated. 
Eighteen commonly used surfactant ingredients including nine anionic, four amphoteric, and five nonionic surfactants were investigated in the study. Single application patch test of 24 hours was conducted on the back of human volunteers. In vitro methodologies including zein solubilization test, cytotoxicity assay, and HET-CAM test were performed with the same ingredients. Solubilized zein, protein similar to keratin, was isolated and assayed for protein using the BCA protein assay kit and cell viability was measured by cytotoxicity assay on HaCaT cell line.
For anionic and amphoteric surfactants, HET-CAM test results showed strong positive correlation with human patch test results whereas zein test and cytotoxicity assay data did not agree well with in vivo data. HET-CAM test was especially highly predictive for surfactants that elicited strong irritation in the patch test. On the other hand, for nonionic surfactants zein test results showed higher positive correlation with patch test results than other two in vitro methods did. The relevance of each in vitro method with in vivo test varied depending on the type of surfactant, and therefore characteristics of surfactant should be considered in evaluation of surfactants. Finally, when irritation potential of body cleanser composition with mild surfactants was compared with that of commercially available body cleansing product, mild surfactant-based formulation showed less irritation than the control product in both patch test and HET-CAM test.

Comparison of in vivo and in vitro tests to predict the irritation potential of surfactants and cleansing formulation